bluuebunny/crossref_metadata_2025 huggingface dataset:
Variation in two phases of post‐winter development of a butterfly
Authors: Stålhandske S. , Gotthard K. , Posledovich D. , Leimar O.
Published: October 2014

The temporal aspects of life cycle characteristics, such as diapause development, are under strong selection in seasonal environments. Fine‐tuning of the life cycle may be particularly important to match the phenology of potential mates and resources as well as for optimizing abiotic conditions at eclosion. Here, we experimentally study the spring phenology of the orange tip butterfly, Anthocharis cardamines, by analysing post‐winter pupal development in three populations along a latitudinal cline in each of Sweden and the United Kingdom. These countries differ substantially in their seasonal temperature profile. By repeatedly recording pupal weights, we established that post‐winter development has two separate phases, with a more rapid weight loss in the second phase than in the first, likely corresponding to a ramping up of the rate of development. Variation in the duration of the first phase contributed more strongly than the second phase to the differences in phenology between the localities and sexes. We found that insects from Sweden had a faster overall rate of development than those from the United Kingdom, which is consistent with countergradient variation, as Sweden is colder during the spring than the United Kingdom. Similar trends were not observed at the within‐country scale, however. A cogradient pattern was found within Sweden, with populations from the north developing more slowly, and there was no clear latitudinal trend within the United Kingdom. In all localities, males developed faster than females. Our results point to the importance of variation in the progression of post‐winter development for spring phenology.
Subprime Mortgage Defaults and Credit Default Swaps
Authors: ARENTSEN ERIC , MAUER DAVID C. , ROSENLUND BRIAN , ZHANG HAROLD H. , ZHAO FENG
Published: October 2014

We offer the first empirical evidence on the adverse effect of credit default swap (CDS) coverage on subprime mortgage defaults. Using a large database of privately securitized mortgages, we find that higher defaults concentrate in mortgage pools with concurrent CDS coverage, and within these pools the loans originated after or shortly before the start of CDS coverage have an even higher delinquency rate. The results are robust across zip code and origination quarter cohorts. Overall, we show that CDS coverage helped drive higher mortgage defaults during the financial crisis.
Prospective comparison of single port versus conventional laparoscopic surgery for ectopic pregnancy
Authors: Kim Min Kyung , Kim Jeong Jin , Choi Joong Sub , Eom Jeong Min , Lee Jung Hun
Published: October 2014

Aim

To investigate the feasibility and safety of single port laparoscopic surgery (SP‐LS) for ectopic pregnancy, irrespective of type of ectopic pregnancy and hemodynamic stability.

Methods

A prospective case–control study of 106 women who underwent SP‐LS or conventional LS for a suspected ectopic pregnancy was performed at a university teaching hospital from January 2009 to March 2012. Twenty‐six women underwent SP‐LS (SP‐LS group) and 80 women underwent conventional LS (conventional LS group).

Results

There were no statistical differences between the groups in terms of demographic characteristics, operating time, hemoglobin change, return of bowel activity, hospital stay or complication rate. There were no cases of additional trocar use or conversion to laparotomy. Of five women with heterotopic pregnancy, one underwent SP‐LS, and three underwent conventional LS for tubal pregnancy, which all resulted in vaginal delivery without obstetric complication; one woman received SP‐LS for cornual pregnancy and had an ongoing pregnancy.

Conclusion

SP‐LS for ectopic pregnancy is feasible and safe regardless of the type of ectopic pregnancy and hemodynamic stability. However, further work is needed to confirm this conclusion and to demonstrate any advantage of SP‐LS for ectopic pregnancy.
Extraversion and Agreeableness: Divergent Routes to Daily Satisfaction With Social Relationships
Authors: Tov William , Nai Ze Ling , Lee Huey Woon
Published: October 2014

We examined the unique effects of extraversion and agreeableness (and honesty‐humility) on everyday satisfaction with family, friends, romantic life, and acquaintances, and explored potential mediators of these effects. Three diary studies (Ns = 206, 139, 185) were conducted on Singaporean university students. In Studies 1 and 2, participants rated their satisfaction with different relationship categories. In Study 3, participants rated their satisfaction and social interactions with 10 target individuals each day for a 1‐week period. Both extraversion and agreeableness predicted relationship satisfaction. However, the effect of extraversion was mediated by greater levels of trust in others, whereas the effect of agreeableness was mediated by less frequent negative exchanges (e.g., criticism, perceived anger, and perceived neglect). The effect of honesty‐humility on negative exchanges was similar to agreeableness. When both were entered as predictors, only the effect of honesty‐humility was significant. We discuss how the processes by which personality affect relationship satisfaction vary depending on the trait as well as the particular measure that is used (IPIP NEO PI‐R, California Q‐Set, and IPIP‐HEXACO).
Age-Related Prevalence Rates of Sexual Difficulties, Sexual Dysfunctions, and Sexual Distress in Heterosexual Women: Results from an Online Survey in Flanders
Authors: Hendrickx Lies , Gijs Luk , Enzlin Paul
Published: October 2014

Introduction

Although age-related prevalence rates of female sexual difficulties, i.e., difficulties with sexual desire, arousal, orgasm, or pain have occasionally been studied—with mostly inconsistent results—the age-related prevalence rates of female sexual dysfunctions, i.e., sexual difficulties that are associated with sexual distress, have not. Moreover, the association of age with sexual distress, i.e., distress due to sexual difficulties, has almost completely been neglected in epidemiological research.

Aims

The aims of the present study were to provide age-related prevalence estimates of sexual difficulties and sexual dysfunctions and to provide proportions of participants reporting sexual distress in heterosexual women.

Methods

An online survey comprising on sexual difficulties (i.e., low sexual desire, lack of responsive sexual desire, difficulties with lubrication, lack of subjective sexual arousal, absent or delayed orgasm, and dyspareunia) and associated sexual distress that enables us to classify respondents with sexual dysfunctions.

Main Outcome Measure

Sexual Functioning Scale.

Results

A total of 15,048 heterosexual women aged 16–74 years living in Flanders (the Nothern, Dutch-speaking part of Belgium) completed the online survey. This study revealed that all sexual difficulties and all sexual dysfunctions are significantly associated with age in women. Although most sexual difficulties and sexual dysfunctions increase with age, some display a U-shaped association with age. Furthermore, it was found that—except for lubrication difficulties—sexual distress was also significantly associated with age and that sexual distress is more common in younger women.

Conclusion

The association between age and sexual difficulties, sexual dysfunctions, and sexual distress in women is complex and deserves more attention from scholars.
Positive, Proactive, and Committed: The Surprising Connection Between Good Citizens and Expressed (vs. Suppressed) Anger at Work
Authors: Stickney Lisa T. , Geddes Deanna
Published: October 2014

In two studies, we examine the relationship of positive and negative trait affectivity (PA/NA), organizational commitment, and emotional exhaustion with organizational member anger. Utilizing the dual threshold model (DTM) constructs of expressed and suppressed anger (Geddes & Callister, 2007), we find employees with high organizational commitment express anger to relevant others, that is, to management or to those responsible for the anger‐provoking situation. In contrast, emotionally exhausted employees and those with high NA tend to suppress their anger, venting only to uninvolved parties or remaining silent. Findings also indicate a positive relationship with PA and anger expression—a connection rarely considered or examined in anger research. Further, expressed anger was predictive of perceived improvement with problematic situations, while suppressed anger forms led to perceptions that the situation at work deteriorated.
When Should We Disagree? The Effect of Relationship Conflict on Team Identity in East Asian and North American Teams
Authors: Liang Lindie H. , Adair Wendi L. , Hideg Ivona
Published: October 2014

Along with recent research uncovering distinctly Asian approaches to conflict management, we examine the experience and effect of relationship conflict on team identity in culturally homogeneous North American versus East Asian teams. In a longitudinal field experiment with student teams, we found that East Asian teams, compared to North American teams, experienced more relationship conflict at later stages of team tenure. We further found that, while relationship conflict undermined team identity in North American teams, relationship conflict did not influence team identity in East Asian teams. Our study counterintuitively finds that East Asian teams may be less influenced by relationship conflict than North American teams, despite their relationship maintenance orientation. We present several possible future avenues to unpack the psychological mechanisms underlying the distinct temporal patterns and outcome effects of relationship conflict in East Asian teams and implications for cross‐cultural East Asian and North American teams.
Effect of ultra‐low dose and standard heparin locks on early tunnelled dialysis catheter outcomes in low‐risk dialysis patients
Authors: Renaud Claude J , Lim Eng Kuang , Tho Samuel J , Yeoh Lee Ying
Published: October 2014

Aim

Initial heparin locks instilled after tunnelled dialysis catheter (TDC) insertion can leak causing systemic anticoagulation and also promote staphyloccocal biofilm formation, predisposing to catheter‐related infection (CRI). The 1000 U/mL concentration is thus advocated as the optimal dose for preventing catheter bleeding and malfunction. The effect of lower heparin concentrations on further lowering these complications is not known. We compared early TDC outcomes between a non‐standard ultra‐low (500 U/mL) and standard initial heparin locks (1000 and 5000 U/mL).

Methods

This was a retrospective study on prospectively collected data on 238 de novo internal jugular TDCs placed by nephrologists. Cases were categorized into groups 1, 2 and 3, according to initial heparin lock: 500 [n = 30], 1000 [n = 180] and 5000 U/mL [n = 28] respectively. Bleeding and malfunction within 24 h of TDC insertion, 30 days CRI‐free catheter survival and the effects of clinical and laboratory factors on bleeding were evaluated.

Results

Bleeding events were similar in groups 1, 2 and 3 (7 vs 14 vs 13%, respectively, P = 0.61). Malfunction was only seen in group 2 (3.3%). Thirty‐day CRI‐free catheter survival was comparable (96 vs 98 vs 97%, respectively, P = 0.22), giving a cumulative CRI rate of 0.76/1000 catheter days. All CRIs were staphylococcal. Univariate analysis did not reveal any significant predictors of catheter bleeding.

Conclusion

Immediate TDC bleeding, malfunction and CRI rate are not influenced by heparin lock concentrations ≤5000 U/mL in this low‐risk cohort. However this needs to be corroborated in higher risk patients.
Oxytocin down‐regulates mesenteric afferent sensitivity via the enteric OTR/nNOS/NO/KATP pathway in rat
Authors: Li J. , Xue B. , Han T. , Huang K. , Gong L. , Ma X. , Liu K. , Cui S. , Zhang M. , Kunze W. , Liu C.
Published: October 2014

Background

Oxytocin plays an analgesic role in modulation of nociception and pain. Most work to date has focused on the central mechanisms of oxytocin analgesia, but little is known about whether peripheral mechanisms are also involved.

Methods

The mesenteric afferent discharge was recorded in vitro. The expressions of oxytocin receptor (OTR) and neuronal nitric oxide synthase (nNOS) in longitudinal muscle myenteric plexus (LMMP) was identified by immunofluorescence.

Key Results

Oxytocin per se had no effect on the jejunal mesenteric afferent discharge, however, it markedly attenuated the bradykinin‐ or distention‐evoked increase of mesenteric afferent discharge, which was mimiced by the nitric oxide (NO) donor sodium nitroprusside (SNP). Pretreatment of either NOS inhibitor L‐NAME or NPLA largely reduced the inhibitory effect of oxytocin on bradykinin‐evoked mesenteric afferent discharge. Such effect, to a large extent, was also alleviated by N‐and P‐type voltage‐dependent calcium channel antagonists or KATP blocker glibenclamide. In addition, immunofluorescence studies show strong colocalization of OTR with nNOS in LMMP of the rat jejunum.

Conclusions & Inferences

Oxytocin down‐regulates the mesenteric afferent sensitivity through nNOS‐NO‐KATP pathway. Our findings may reveal a new peripheral mechanism for oxytocin analgesia.
Geometric morphometric analysis applied to theropod tracks from the Lower Cretaceous (Berriasian) of Spain
Authors: Castanera Diego , Colmenar Jorge , Sauqué Víctor , Canudo José I.
Published: October 2014

Geometric morphometric methods applied to theropod tracks from the Huérteles Formation (Berriasian, Spain) are here shown to be invaluable for drawing comparisons between theropod tracks with different preservation modes (true tracks, shallow undertracks and natural casts) or differing in the preservation of anatomical features (e.g. digital pads). Principal components analysis and thin‐plate spline methods can quantitatively distinguish between the broad groups of tracks in a sample and establish the main differences between them. These methods offer a promising approach for estimating ichnodiversity, achieved by evaluating just the morphology of the tracks independent of other factors such as size. The theropod tracks of the Huérteles Formation can be classified into two broad groups: minute‐to‐medium‐sized gracile theropod tracks (Kalohipus bretunensis) and medium‐to‐large‐sized robust theropod tracks (Iberosauripus). The presence of a third group of more gracile medium‐to‐large‐sized theropod tracks (Megalosauripus) cannot be proven with certainty on the basis of the current data. These results indicate that the theropod ichnodiversity of the Huérteles Formation is probably lower than that estimated by means of conventional methods alone (e.g. qualitative description of the tracks) and that many of the described theropod morphotypes may represent extramorphological or ontogenetic variations of other morphotypes.
Extracorporeal membrane oxygenation support after pediatric orthotopic heart transplantation
Authors: Su Jennifer A. , Kelly Robert B. , Grogan Tristan , Elashoff David , Alejos Juan C.
Published: October 2014

Mechanical circulatory support has been used for more than 30 yr to allow the heart to recover from ischemia and injury. There are limited pediatric data, however, on the efficacy of ECMO in the setting of post‐transplantation support for primary graft dysfunction or rejection. Data from all patients at our university‐affiliated, tertiary care children's hospital who underwent OHT between 1998 and 2010 and required subsequent ECMO support were analyzed. The primary outcome measure was survival to hospital discharge. Two hundred and three pediatric patients underwent OHT between 1998 and 2010 at our institution. Twenty‐nine of these patients experienced post‐transplantation cardiac failure requiring ECMO support, 18 of whom survived to hospital discharge (62%). Survival in the rejection and allograft vasculopathy group was 75%, and survival in patients with primary graft failure was 53% after ECMO support (p = 0.273). Patient survival to hospital discharge was not associated with ischemic time or duration of ECMO. ECMO provides hemodynamic support in the setting of cardiac failure and can be used successfully after pediatric OHT for primary graft dysfunction or rejection.
Beyond Pivotal Politics: Constituencies, Electoral Incentives, and Veto Override Attempts in the House
Authors: Hickey Patrick T.
Published: October 2014

Veto override attempts offer an ideal opportunity to study the president's influence in Congress. A bill's content is identical during final passage and veto override votes, yet some members of Congress vote differently on these two roll‐calls. This article focuses on those members of Congress who switch their votes to join, or defect from, the president's coalition during veto override votes. The empirical analysis investigates veto override attempts from 1973 to 2011 to determine which members of Congress are most likely to change their votes during veto overrides. I find that the president's ability to win, or keep, members' support on veto override votes is determined in part by members' electoral incentives and the president's strength in members' constituencies. In particular, the president's strength in members' constituencies makes presidential party members more likely to join the president's veto override coalition and also makes opposition party members more likely to defect from the president's veto override coalition. Accounting for the influence of constituencies and electoral incentives augments party‐based and ideology‐based theories of congressional behavior and thus helps build richer, more comprehensive, and more accurate theories of member behavior.
Kennedy, Johnson, and Policy toward China: Testing the Importance of the President in Foreign Policy Decision Making
Authors: Newmann William W.
Published: October 2014

While scholars may be pleased with parsimonious models of the presidency in which institutional variables determine presidents' decision‐making structures, veteran policy makers argue that scholars miss the essence of decision: people make decisions. This article tests the impact of the president as a variable. The transition from Kennedy to Johnson is a case where all variables remained the same, except the occupant of the Oval Office. Study of the impact of a new president on decision making toward China helps define the influence of both institutional and presidential‐centered variables as well as the importance of senior presidential advisors.
The Contemporary Presidency After the Orders: Presidential Memoranda and Unilateral Action
Authors: Lowande Kenneth S.
Published: October 2014

An important vein of presidency scholarship has focused on the president's instruments of unilateral action through systemic considerations of executive orders, proclamations, and most recently, signing statements. This article considers an additional tool: presidential memoranda. I argue these memoranda contain important policy content advancing the president's agenda, and—like executive orders—they often indicate unilateral action. Memoranda use has surged as the issuance of executive orders has decreased, indicating that unilateralism is not declining, but rather, the means of such action may be shifting.
Conditions for view invariance in the neural response to visual symmetry
Authors: Makin Alexis D. J. , Rampone Giulia , Bertamini Marco
Published: October 2014

Symmetry detection is slow when patterns are distorted by perspective, perhaps due to a time‐consuming normalization process, or because discrimination relies on remaining weaker regularities in the retinal image. Participants viewed symmetrical or random dot patterns, either in a frontoparallel or slanted plane (±50°). One group performed a color discrimination task, while another performed a regularity discrimination task. We measured a symmetry‐related event‐related potential (ERP), beginning around 300 ms. During color discrimination, the ERP was reduced for slanted patterns, indexing only the remaining retinal structure. During regularity discrimination, the same ERP was view invariant, and identical for frontoparallel or slanted presentation. We conclude that normalization occurs rapidly during active symmetry discrimination, while symmetry‐sensitive networks respond only to regularity in the retinal image when people are attending to other features.
EU Legislation to Reduce Carbon Emissions from Cars: Intergovernmental or Supranational Policy Making?
Authors: Gulbrandsen Lars H. , Christensen Anne Raaum
Published: October 2014

This article examines the making and implementation of the 2009 European Union (EU) regulation on cars and CO2 emissions (Regulation [EC] No 443/2009). As the first legally binding measure to target the CO2 emissions of passenger cars, this regulation represents a milestone in EU efforts to reduce the climate impacts of road transport. The analysis draws on two central theoretical perspectives on EU policy making: liberal intergovernmentalism and supranationalism. Both offer important insights, but their explanatory power varies with the policy‐making phase in focus. The analysis shows that the Commission and the car industry were instrumental in shaping what eventually became an industry‐friendly regulation applicable in all EU countries. However, far from being a case of closed negotiations between the industry and the Commission, Germany and other EU countries defending the interest of manufacturers of high‐emission vehicles made use of their powers during the decision‐making phase and succeeded in watering down the Commission's proposal.
Cladistic analysis of Omalodini Kryzhanovskij (Coleoptera: Histeridae: Histerinae)
Authors: LEIVAS FERNANDO W. T. , BICHO CARLA L. , ALMEIDA LÚCIA M.
Published: October 2014

According to the current Histeridae classification, Omalodini is composed of 100 species described in 12 genera distributed in the Neotropical, Afrotropical, Afrotemperate and Oriental regions: Asolenus Lewis; Atribalus Bickhardt; Blypotehus Vienna, Ebonius Lewis; Lewisister Bickhardt; Notolister Lewis; Omalodes Erichson, divided in Omalodes (Omalodes), O. (Diplogrammicus) Lewis and O. (Cornillus) Lewis; Perfidolenus Vienna; Rhypochares Marseul; Scapomegas Lacordaire; Sphyracus Marseul; Theropatina Mazur. Our aims were to test the monophyly of Omalodini, using cladistic analysis, and propose a hypothesis of the phylogeny of the tribe. The matrix was composed of 49 terminal taxa (34 from the ingroup and 15 from the outgroup) and 131 characters of the adult morphology. The data were analysed under equal weights and implied weights. In both analyses, Omalodini represents a polyphyletic group and the trees obtained from equal weights analysis (two most parsimonious trees) were chosen in order to recover the tribe's monophyly. We recognize three lineages in Omalodini: Ebonius, undescribed genus and Omalodes, being supported by six transformations (Ebonius + (undescribed genus + Omalodes)). The sister group of Omalodini was defined as a clade composed of Histerini, Platysomatini and Hololeptini. The subgenera of Omalodes were not resolved consistently under different implied weight analyses. It is necessary to emphasize that Omalodes (Omalodes) comprises the largest group of Omalodini and requires an analysis with better sampling for more precise resolution of the internal phylogeny of the genus. The groups excluded a posteriori from Omalodini, Theropatina, Asolenus, Atribalus, Blypotehus, Lewisister, Notolister, Perfidolenus, Rhypochares, Sphyracus and Scapomegas, could not be allocated to any of the existing tribes of Histerinae.
Genomic full‐length sequence of two HLA‐A alleles, A*03:01:01:01 and A*03:02:01 identified by cloning and sequencing
Authors: Tao H. , Xu Y. P. , Chen L. X.
Published: October 2014

Genomic full‐length sequences of HLA‐A*03:01:01:01 and A*03:02:01, were identified in two Chinese donors.
Identification of a novel HLA‐A*26 allele, HLA‐A*26:01:36, in a Turkish family by sequence‐based typing
Authors: Sari G. , Yazar M. , Tozkir H. , Duymaz J. , Gürkan H.
Published: October 2014

HLA‐A*26:01:36 differs from the closest allele HLA‐A*26:01:01 by a nucleotide change at the position 114.
A novel allele, HLA‐DPB1*296:01, identified by sequence‐based typing in a Thai bone marrow donor
Authors: Presciuttini S. , Sciarrino R. , Fornaciari S. , Mariotti M. L. , Scatena F. , Curcio M.
Published: October 2014

A novel HLA‐DPB1 allele, named DPB1*296:01, was identified in the Thai mother of a hematologic patient.
The HLA‐A*02:481 allele was identified in unrelated Brazilians sharing HLA‐B*15:17, C*07:01P, DRB1*13:02 and DQB1*06:04
Authors: Echeverria V. F. , Rampim G. F. , Gerbase‐DeLima M.
Published: October 2014

HLA‐A*02:481 differs from HLA‐A*02:01:01:01 by one nucleotide and was found in four unrelated Brazilians.
A novel HLA‐A allele, A*74:23, identified in an individual from Costa Rica
Authors: Arrieta‐Bolaños E. , McWhinnie A. J. , Madrigal‐Sánchez J. J. , Calvo L. , Salazar‐Sánchez L. , Madrigal J. A. , Marsh S. G. E. , Shaw B. E.
Published: October 2014

The new HLA‐A*74:23 allele differs from the closest allele A*74:01 by a nucleotide change in exon 3 at codon 97.
Peritoneal dialysis vs. haemodialysis in the management of paediatric acute kidney injury in Kano, Nigeria: a cost analysis
Authors: Obiagwu Patience N. , Abdu Aliyu
Published: October 2014

Objective

To determine the cost of the dialytic management of paediatric acute kidney injury in a low‐income country.

Methods

All children under the age of 15 years, who had either peritoneal dialysis or haemodialysis for acute kidney injury in Aminu Kano Teaching Hospital over a 1‐year period, were studied. The average cost of each dialysis modality was estimated.

Results

Of 20 children, who had dialysis for acute kidney injury, 12 (60%) had haemodialysis and 8 (40%) had peritoneal dialysis. The mean cost for haemodialysis exceeded that of peritoneal dialysis ($363.33 vs. $311.66, t = 1.04, P = 0.313) with the mean cost of consumables significantly accounting for most of the cost variation ($248.49 vs. $164.73, t = 2.91, P = 0.009). Mean costs of nephrologist visit and nursing were not found to be significant.

Conclusion

Peritoneal dialysis is the less costly alternative for managing acute kidney injury in children in our environment.
The proportion and trend of human immunodeficiency virus infections associated with men who have sex with men from Chinese voluntary blood donors: a systematic review and meta‐analysis
Authors: Lu Jinxin , Xu Junjie , Reilly Kathleen Heather , Li Yongze , Zhang Christiana Meng , Jiang Yongjun , Geng Wenqing , Wang Lunan , Shang Hong
Published: October 2014

Background

Human immunodeficiency virus (HIV)‐positive cases associated with men who have sex with men (MSM) have rapidly increased over the past years. The objective of this study is to comprehensively evaluate the proportions, changing trends, and geographical distribution of MSM‐associated HIV cases from Chinese voluntary blood donors by systematically reviewing the available literature.

Study Design and Methods

Major English and Chinese research databases were searched for studies reporting study locations, study years, the number of HIV infections among blood donors, and the number of HIV‐positive donations associated with MSM in China. The proportion estimates were calculated; subgroup analyses and test for time trend were performed using software of comprehensive meta‐analysis.

Results

Thirty‐four studies met eligibility criteria. The pooled proportion of HIV‐positive donations associated with MSM from 2001 to 2012 was 36.5% (95% confidence interval, 29.6%‐44.1%). The epidemic was found to be more severe in northeast and north China compared to south China (59.6%; 55.0% vs. 3.8%, respectively). The proportion showed a significantly increasing trend over the study period (10.3% in 2001‐2005; 38.6% in 2006‐2009; and 47.6% in 2010‐2012; trend test chi‐square = 16.42, p < 0.001).

Conclusion

The relatively high proportion of MSM‐ associated HIV‐positive donors is of concern. Efficient and effective measures focused on public education and improving knowledge of blood safety are needed to prevent this at‐risk population from seeking HIV testing through blood donation. It is also imperative to expand the scope of postdonation nucleic acid testing to shorten the window period to improve blood supply safety in China.
Compensation of Gravity Induced Heliostat Deflections for Improved Optical Performance
Authors: Yuan James K. , Christian Joshua M. , Ho Clifford K.
Published: October 2014

Heliostat optical performance can be affected by both wind and gravity induced deflections in the mirror support structure. These effects can result in decreased energy collection efficiency, depending on the magnitude of structural deflections, heliostat orientation and field position, and sun position. This paper presents a coupled modeling approach to evaluate the effects of gravity loading on heliostat optical performance, considering two heliostat designs: The National Solar Thermal Test Facility (NSTTF) heliostat and the Advanced Thermal Systems (ATS) heliostat. Deflections under gravitational loading were determined using finite element analysis (FEA) in Ansys Mechanical, and the resulting deformed heliostat geometry was analyzed using Breault Apex optical engineering software to evaluate changes in beam size and shape. Optical results were validated against images of actual beams produced by each respective heliostat, measured using the Beam Characterization System (BCS) at Sandia National Laboratories. Simulated structural deflections in both heliostats were found to have visible impacts on beam shape, with small but quantifiable changes in beam power distribution. In this paper, the combined FEA and optical analysis method is described and validated, as well as a method for modeling heliostats subjected to gravitational deflection and canted in-field, for which mirror positions may not be known rigorously. Furthermore, a modified, generalized construction method is proposed and analyzed for the ATS heliostat, which was found to give consistent improvements in beam shape and up to a 4.1% increase in annual incident power weighted intercept (AIPWI).
Comparison of Alkaline Direct Ethanol Fuel Cells With and Without Anion Exchange Membrane
Authors: Huang Jing , Faghri Amir
Published: October 2014

The performance of three alkaline direct ethanol fuel cells (ADEFCs) is investigated. All three use identical anode and cathode electrodes, but one uses an anion exchange membrane (AEM) and the other two use non-permselective porous separators. Ethanol was chosen as the fuel because of its low toxicity, low carbon footage and market readiness. A direct comparison between ADEFCs with and without AEM is reported. The performance of each cell is studied under different operation conditions of temperature, reactants flow rate, ethanol and KOH concentrations. The results show that with low cost porous separator, the ADEFC can reach similar power output as those using expensive AEMs. With 1 M ethanol and 1 M KOH aqueous solution, the maximum power densities of 26.04 mW/cm2 and 24.0 mW/cm2 are achieved for the ADEFC employing AEM and non-woven fabric separator, respectively. This proves the feasibility of replacing AEM with non-permselective separators. The results suggest that improving the cathode structure in order to provide a better oxygen supply is a key factor to enhance the performance of an anion exchange membrane free ADEFC.
Power Generation From Thermal Transpiration Based Pumping Devices
Authors: Zeng Pingying , Wang Kang , Falkenstein-Smith Ryan , Ahn Jeongmin , Ronney Paul D.
Published: October 2014

This study examines the successful development of a combustion-driven thermal transpiration-based combustor and a self-sustaining gas pump system having no moving parts and using readily storable hydrocarbon fuel. A stacked configuration was then integrated into the combustor creating a self-sustaining power generation system. In recent years, power generation devices employing hydrocarbon fuels rather than electrochemical storage as energy feedstock have been studied extensively due to the much higher energy densities of hydrocarbon fuels than the best available batteries. While many devices have been proposed including internal combustion engines and gas turbines, they all require the use of air to obtain a higher energy density so that only one reactant (fuel) need be carried. Thermal transpiration was accomplished by meeting two essential conditions: (1) gas flow in the transitional or molecular regime using glass microfiber filters as transpiration membranes and (2) a temperature gradient through the membrane using catalytic combustion downstream of the membrane. A cubic combustor was designed to house the thermal transpiration membrane and develop into a self-sustaining gas pump system. Fuel/Air would feed through an inlet into a mixing chamber that would flow into the thermal guard containing the thermal transpiration membrane. The thermal guard was developed from a high thermal conductivity stainless steel made into a cubic formation by using a 3D printing process. This configuration allowed both fuel and air to be transpired through the membrane meaning it was not possible for any reactant flow to occur as a result of the fuel supply pressure and only the membrane could draw reactants into the device.

In addition to pumping, a single-chamber solid-oxide fuel cell (SC-SOFC) was incorporated into combustion driven thermal transpiration pumps to convert chemical or thermal energy into electrical energy for a self-contained portable power generation system. Experiments showed that transpiration pumps with larger porosity and larger overall size exhibited better performance, though membrane pore size had little effect. These results were quantitatively consistent with theoretical predictions. By exploiting the temperature and fuel/oxygen concentrations within the transpiration pump, the SOFC achieved a maximum power density of 40 mW/cm2. Despite being far lower than necessary for a power source to be competitive with batteries, this preliminary study signifies an on-going positive efficiency that has potential for improvement through optimizing SOFC technology.
Large Scale Energy Storage Using MW-Size PEM Electrolysis
Authors: Anderson Everett B. , Ayers Katherine E. , Dalton Luke , Schiller Mark
Published: October 2014

With the ever-increasing addition of wind and solar renewable energy to the traditional electric grid, the need for energy storage also grows. A recent study projects the value of energy storage for wind and solar integration worldwide to exceed $30 Billion by 2023 [1]. Hydrogen from electrolysis is a promising technology for renewable energy capture as it has the capability to store massive amounts of energy in a relatively small volume. In addition, electrolysis can also provide ancillary services to the grid such as frequency regulation and load shifting resulting in multiple value streams. The hydrogen produced can alternatively be injected into the natural gas pipeline (thus making that energy carrier more green), in the production of high value chemicals such as ammonia, in upgrading of methanization-produced biogas, or used as a transportation fuel.

Europe in particular has been committed to these pathways and making heavy investment in both materials research and system design and development as well as technology demonstration. In Germany, hydrogen is looked upon as a key part of the energy storage solution under “Energiewende,” their national sustainable energy transition plan. Hydrogen provides a unique link between the electric and gas grid infrastructures (often referred to as “Power-to-Gas”). Germany is also considered the global leader in biogas energy generation, with 18,244 GWh of generation in 2012 forecasted to grow to 28,265 GWh by 2025 [2].

Water electrolysis has benefits over other hydrogen generation technologies due to the lack of carbon footprint when integrated with a renewable source of energy. Specifically, proton exchange membrane (PEM) electrolysis is a promising technology for hydrogen generation applications because of the lack of corrosive electrolytes, small footprint, and ability to generate at high pressure, requiring only water and an energy source. Several companies have already announced plans to develop megawatt (MW) commercial scale PEM electrolysis units in the 2014–2015 timeframe for these applications. There have also been recent announcements of large scale renewable energy storage project based on electrolysis.
Two-Phase Flow Pressure Drop Measurement in PEM Fuel Cell Flow Channels
Authors: Mortazavi Mehdi , Tajiri Kazuya
Published: October 2014

Proton exchange membrane (PEM) fuel cells produce power with water and heat as inevitable byproducts. Accumulated liquid water within gas channel blocks the reactant flow and cause pressure drop along the gas channel. It is of extreme importance to accurately predict the liquid and gas two-phase flow pressure drop in PEM fuel cell flow channels. This pressure drop can be considered as an in-situ diagnostic tool that reveals information about the amount of liquid water accumulated within the flow channels. In this paper, the two-phase flow pressure drops are measured in ex-situ PEM fuel cell parallel flow channels. The pressure drops were measured for air mass fluxes of 2.4–6.3kg/m2s and water mass fluxes of 0.0071–1.28kg/m2s. These mass fluxes correspond to 2–5.33m/s and 7.14 × 10−6 – 0.0012m/s air and water superficial velocities, respectively. The measured two-phase flow pressure drops are then compared with different two-phase flow pressure drop models. Qualitative and quantitative comparison between the experimental results and existing models is provided in this work.
Fuel Composition Transients in Fuel Cell Turbine Hybrid for Polygeneration Applications
Authors: Harun Nor Farida , Tucker David , Adams Thomas A.
Published: October 2014

Transient impacts on the performance of solid oxide fuel cell / gas turbine (SOFC/GT) hybrid systems were investigated using hardware-in-the-loop simulations (HiLS) at a test facility located at the U.S. Department of Energy, National Energy Technology Laboratory. The work focused on applications relevant to polygeneration systems which require significant fuel flexibility. Specifically, the dynamic response of implementing a sudden change in fuel composition from syngas to methane was examined. The maximum range of possible fuel composition allowable within the constraints of carbon deposition in the SOFC and stalling/surging of the turbine compressor system was determined.

It was demonstrated that the transient response was significantly impact the fuel cell dynamic performance, which mainly drives the entire transient in SOFC/GT hybrid systems. This resulted in severe limitations on the allowable methane concentrations that could be used in the final fuel composition when switching from syngas to methane. Several system performance parameters were analyzed to characterize the transient impact over the course of two hours from the composition change.
Developing a Two-Dimensional Model of a Proton Exchange Membrane Fuel Cell in FreeFem++
Authors: Aiyejina Ararimeh , Marquez Andres , Sastry M. K. S.
Published: October 2014

This work presents the use of non-commercial software for the design and development of a multiphysics model for some aspects of a proton exchange membrane fuel cell’s (PEMFC) operation and performance. Developing the model this way gives users greater freedom to adjust and improve upon the model than with common commercial modeling software packages. By using the non-commercial partial differential equation (PDE) solver FreeFem++, which utilizes a high-level programming language based on C++, we developed a model in which the set of equations representing the mechanisms that govern PEMFC operation and the algorithms for solving it can be freely tweaked, updated or overhauled by users.

We discuss our choice of software and describe the advantages and limitations of our modeling approach, such as the flexibility provided by its open nature at the cost of added programming complexity compared to commercial packages. We also note how the geometry of the cell being modeled can easily be controlled through a set of user-defined parameters, or scripted to change for successive model runs as part of an optimization procedure or sensitivity analysis. We present results from a two-dimensional model for the cathode side in order to demonstrate the practicality of this approach.
Evaluation of Cathode Air Flow Transients in a SOFC/GT Hybrid System Using Hardware in the Loop Simulation
Authors: Zhou Nana , Yang Chen , Tucker David
Published: October 2014

Thermal management in the fuel cell component of a direct fired solid oxide fuel cell gas turbine (SOFC/GT) hybrid power system, especially during an imposed load transient, can be improved by effective management and control of the cathode air mass flow. The response of gas turbine hardware system and the fuel cell stack to the cathode air mass flow transient was evaluated using a hardware-based simulation facility designed and built by the U.S. Department of Energy, National Energy Technology Laboratory (NETL).

The disturbances of the cathode air mass flow were accomplished by diverting air around the fuel cell system through the manipulation of a hot-air bypass valve in open loop experiments. The dynamic responses of the SOFC/GT hybrid system were studied in this paper.

The evaluation included distributed temperatures, current densities, heat generation and losses along the fuel cell over the course of the transient along with localized temperature gradients. The reduction of cathode air mass flow resulted in a sharp decrease and partial recovery of the thermal effluent from the fuel cell system in the first 10 seconds. In contrast, the turbine rotational speed did not exhibit a similar trend. The collection of distributed fuel cell and turbine trends obtained will be used in the development of controls to mitigate failure and extend life during operational transients.
Next Generation Hydrogen Production Systems Using Proton Exchange Membrane Electrolysis
Authors: Colella Whitney G. , James Brian D. , Moton Jennie M. , Ramsden Todd G. , Saur Genevieve
Published: October 2014

This article details analysis of hydrogen (H2) production based on polymer electrolyte membrane (PEM) electrolysis. This work identifies primary constraints to the success of this production pathway, primary cost drivers, and remaining Research and Development (R&D) challenges. This research assesses the potential to meet U.S. Department of Energy (DOE) H2 production and delivery (P&D) cost goals of $2 to $4/gasoline gallon equivalent (dispensed, untaxed) by 2020. Pathway analysis is performed using the DOE’s main H2A modeling tool, namely, the H2A Production model, which encapsulates the standard methods of energy, emissions, and cost analysis developed by DOE’s H2 and fuel cell technology teams. PEM electrolysis production pathways are analyzed for a distributed, forecourt H2 production system of 1,500 kilograms (kg) of H2 per day, and for a central, large, plant size H2 production system of 50,000 kg H2/day, for both current and future cases. The analysis is based in part on data from a technical and economic survey completed by four different PEM electrolyzer companies.

Model results indicate that, for PEM electrolysis, the primary cost drivers are the electricity expenditures to run the electrolyzer and the capital cost of the electrolyzer. In the future within the electrolyzer system, the balance of plant is expected to be a greater source of cost than the electrolyzer stack due to stack reductions facilitated by operation at higher current densities whereas the balance of plant remains similarly sized for the given flow. This balance between size and cost of the stack versus balance of plant could also increase difficulties in meeting efficiency improvements in the future. The H2 cost reduction is estimated to be greater moving from a Current case to a Future case, compared with moving from a Forecourt case to a Central case.
Physical Activity at 11 Years of Age and Incidence of Mental Health Problems in Adolescence: Prospective Study
Authors: Hallal Pedro C. , Martínez-Mesa Jeovany , Coll Carolina V.N. , Mielke Grégore I. , Mendes Márcio A. , Peixoto Márcio B. , Munhoz Tiago N. , Ramires Virgilio V. , Assunção Maria Cecilia , Gonçalves Helen , Menezes Ana M. B.
Published: October 2014

Aim:

To evaluate the longitudinal association between physical activity behavior at 11 years of age and the incidence of mental health problems from 11 to 15 years of age.

Methods:

Individuals born in the city of Pelotas, Brazil, in 1993 have been followed up since birth. At 11 and 15 years of age, mental health was assessed using the Strengths and Difficulties Questionnaire (SDQ). At 11 years of age, physical activity was assessed through a validated questionnaire. The continuous SDQ score at 15 years was used as the outcome variable. The main exposure was physical activity behavior at 11 years of age divided into 3 categories (0, 1−299, >300 min/wk).

Results:

The incidence of mental health problems from 11 to 15 years was 13.6% (95% CI, 12.4−14.9). At 11 years, 35.2% of the adolescents achieved 300 min/wk of physical activity. In the unadjusted analysis, physical activity was inversely related to mental health problems (P = .04). After adjustment for confounders, the association was no longer significant in the whole sample but was still significant among boys.

Conclusion:

Physical activity appears to be inversely related to mental health problems in adolescence, but the magnitude of the association is weak to moderate.
Correlates of Physical Activity Among People With Disabilities in South Korea: A Multilevel Modeling Approach
Authors: Kim Youngdeok , Cho Jaehoon , Fuller Dana K , Kang Minsoo
Published: October 2014

Background:

The purpose of this study was to examine the correlates of physical activity (PA) with personal and environmental factors among people with disabilities in South Korea.

Methods:

Data from the 2011 National Survey for Physical Activity and Exercise for the Disabled, conducted by Korea Sports Association for the Disabled, was used (n = 1478). The personal characteristics (age, gender, occupation, types of disabilities, family income) and the numbers of public PA-related facilities (welfare center, public indoor gym, and public outdoor facilities) and social sports/exercise clubs for people with disabilities across 16 local areas were also obtained. Hierarchical generalized linear model was used to examine subjectively measured PA in relation to personal and environmental factors.

Results:

The likelihood of engaging in PA was significantly lower for women with disabilities. People with hearing and intellectual disabilities were less likely to engage in PA compared with those with physical disabilities. The availability of sports/exercise clubs for people with disabilities was the only environmental factor that was significantly associated with PA.

Conclusions:

These findings suggest the need of systematic intervention strategies based upon personal characteristics of people with disabilities. Further public efforts to promote sports/exercise club activities should be encouraged in this population.
Bacterial Imaging Comes of Age
Authors: Wang Xiaojian , Murthy Niren
Published: October 2014

Enterobacteriaceae, a type of highly virulent Gram-negative bacteria, can be imaged in vivo via positron emission tomography with
18
F-sorbitol.
Stem Cell Therapy for Diabetes Comes of Age
Authors: Tesar Paul J.
Published: October 2014

An optimized protocol enables the rapid generation of mature functional human β cells from pluripotent stem cells.