bluuebunny/crossref_metadata_2025 huggingface dataset:
The necessity for testing germination of fresh seeds in studies on diaspore heteromorphism as a life-history strategy
Authors: Baskin Jerry M. , Lu Juan J. , Baskin Carol C. , Tan Dun Y.
Published: May 2013

Many studies have compared diaspore dispersal ability and degree of dormancy in the two diaspores of dimorphic plant species. A primary goal of these studies was to determine if germination and dispersal characteristics of the two morphs fit within a high risk–low risk (bet-hedging) life-history strategy, i.e. high dispersal/low dormancy in one morph versus low dispersal/high dormancy in the other one. In a survey of 26 papers on 28 diaspore dimorphic species, we found that in 12 of the studies, which were published between 1978 and 2008, seeds were stored, and thus possibly afterripened, before they were tested for germination. The 14 papers that tested fresh seeds were published between 1963 and 2010. Failure to test fresh seeds likely resulted in misinterpretation of the diaspore dispersal/dormancy strategy in some of the species investigated. We conclude that it is imperative that fresh seeds be tested for germination in order to be certain that the correct relationship between dispersal and dormancy is elucidated, and thus that the correct interpretation is made concerning life-history strategy and bet-hedging, in dimorphic species.
Increased ischaemia-modified albumin is associated with inflammation in acute rheumatic fever
Authors: Karataş Zehra , Baysal Tamer , Şap Fatih , Alp Hayrullah , Mehmetoğlu Idris
Published: May 2013

Introduction: Ischaemia-modified albumin, a novel biochemical marker for tissue ischaemia, was found to be associated with oxidative stress. The purpose of this study was to assess the role of ischaemia-modified albumin in the diagnosis of acute rheumatic fever and also to evaluate the ischaemia-modified albumin levels in children with heart valve disease. Methods: The study groups, aged 5–18 years, consisted of 128 individuals – 40 with acute rheumatic fever, 35 with congenital heart valve disease, 33 with chronic rheumatic heart disease, and 20 healthy control subjects. Results: The ischaemia-modified albumin, erythrocyte sedimentation rate, and C-reactive protein levels of the acute rheumatic fever group were significantly higher than those in the chronic rheumatic heart disease, congenital heart valve disease, and control groups, separately (p < 0.001). The ischaemia-modified albumin levels in both carditis and isolated arthritis subgroups of children with acute rheumatic fever were significantly higher than in the control group (p < 0.001, p < 0.01, respectively). However, there was no statistically significant difference between the chorea subgroup and control subjects. In addition, significant correlations were observed between ischaemia-modified albumin and acute phase reactants of patients with acute rheumatic fever (p < 0.001 for both erythrocyte sedimentation rate and C-reactive protein). The ischaemia-modified albumin levels of chronic rheumatic heart disease, congenital heart valve disease, and control subjects were similar. Conclusions: The increased level of ischaemia-modified albumin in children with acute rheumatic fever seems to be associated with inflammation. However, further studies are needed to provide stronger evidence.
Treatment of familial hypercholesterolaemia in children and adolescents in the last three decades
Authors: Elis Avishay , Zhou Rong , Stein Evan A.
Published: May 2013

Background:This study evaluated the effectiveness of long-term intensive lipid-lowering therapy in children and adolescents with familial hypercholesterolaemia.Methods:The charts of 89 children and adolescents with heterozygous familial hypercholesterolaemia among ∼1000 patients treated from 1974 to 2008 were reviewed. Familial hypercholesterolaemia was defined as low-density lipoprotein cholesterol level >90th percentile in individuals with a history of familial hypercholesterolaemia.Results:Of the 89 patients, 51% were male; the mean age at diagnosis was 8 ± 4 years, and the mean follow-up was 13 ± 8 years. Baseline and most recent low-density lipoprotein cholesterol levels (mg/dl) under treatment were 250 ± 50 and 142 ± 49, respectively, reduced 43% from baseline (p < 0.0001). At the most recent visit, 39 patients received statin monotherapy, mainly atorvastatin or rosuvastatin, and 50 (56%) patients received combination therapy, mainly vytorin or rosuvastain/ezetimibe, 15 patients were >30 years of age, and none developed symptomatic cardiovascular disease or needed revascularisation.Conclusions:Long-term statin-based therapy can reduce low-density lipoprotein cholesterol levels in most children and adolescents with heterozygous familial hypercholesterolaemia and decrease cardiovascular risk significantly.
The use of levosimendan in children with cancer with severe acute cardiac dysfunction: case series and a review of the literature
Authors: Tosoni Alvise , Dipchand Anne I. , Mohseni-Bod Hadi
Published: May 2013

We report the use of levosimendan in two febrile, neutropenic children with cancer – one post bone marrow transplant – with acute heart failure following chemotherapy. Initial management with epinephrine, milrinone, and diuresis was unsuccessful. Infusion of levosimendan without a loading dose was added to the ongoing heart failure therapy, which resulted in persistent symptomatic and echocardiographic improvement without major side effects.
AMERICAN QUANTITY THEORISTS PRIOR TO IRVING FISHER’STHE PURCHASING POWER OF MONEY
Authors: DE BOYER DES ROCHES JÉRÔME , BETANCOURT REBECA GOMEZ
Published: May 2013

The aim of this paper is to analyze the state of the quantity theory in the United States prior to the publication of Irving Fisher’s ThePurchasing Power of Moneyin 1911. We start by presenting the participants in the monetary debate. Next, we analyze the controversies regarding prices, purchasing power of money, and credit, prior to the Gold Standard Act of 1900, in particular the opposing views of Francis Amasa Walker and James Laurence Laughlin. We then go on to study of the restatement of the quantity theory at the beginning of the twentieth century, through the introduction of credit in the analysis and the statistical tests of the exchange equations. Finally, we study the problems and management of the gold standard, focusing on the elasticity of money supply, the characteristics of the gold exchange standard, and the contrast between the fixed price of gold and its fluctuating purchasing power. We show the improvement of the quantity theory and the new issues that emerged from the rich and original American monetary debate, prior to the publication in 1911 of Fisher’s book.
IRVING FISHER, DEBT DEFLATION, AND CRISES
Authors: SHILLER ROBERT J.
Published: May 2013

This article reconsiders, in the light of the current financial turmoil, Irving Fisher’s 1911 theory of financial crises and his 1933 debt-deflation theory of Great Depressions. Particular attention is given to the role of high debt ratios, high leverage ratios, and changes in the purchasing power of money in Fisher’s analysis, and to Fisher’s compensated dollar plan to stabilize the purchasing power of money. It is argued that indexing the unit of account would accomplish Fisher’s goal of stabilization without the practical difficulties of Fisher’s compensated dollar plan.
IRVING FISHER’S PROGENY AND THE 2008 FINANCIAL CRISIS
Authors: NAKAMURA ALICE ORCUTT
Published: May 2013

Irving Fisher believed in evidence-based decision making. This paper considers how three aspects of Fisher’s methodology could be useful now in the quest to deal with U.S. financial instability: (1) his institutional approach; (2) his efforts to use index number theory as a means to improve official statistics data; and (3) his interest in automating aspects of data analyses. The paper concludes with a call to action for Fisher’s progeny. Actions to solve US financial instability are surely the most fitting possible tribute to Irving Fisher.
IRVING FISHER AND INDEX NUMBER THEORY
Authors: DIEWERT ERWIN
Published: May 2013

There are four main approaches to bilateral index number theory: the fixed basket, stochastic, test, and economic approaches. The paper reviews the contributions of Irving Fisher to these approaches to index number theory, which are still in use today. The paper also reviews Fisher’s contributions to multilateral index number theory. The main themes of the paper are developed in the context of a review of the early history of index number theory: a history that conveys a wealth of information and insight into the making and use of index numbers today.
Delusional versus nondelusional body dysmorphic disorder: recommendations for DSM-5
Authors: Phillips Katharine A. , Hart Ashley S. , Simpson Helen Blair , Stein Dan J.
Published: May 2013

The core feature of body dysmorphic disorder (BDD) is distressing or impairing preoccupation with nonexistent or slight defects in one's physical appearance. BDD beliefs are characterized by varying degrees of insight, ranging from good (ie, recognition that one's BDD beliefs are not true) through “absent insight/delusional” beliefs (ie, complete conviction that one's BDD beliefs are true). The Diagnostic and Statistical Manual of Mental Disorders, 3rd ed., rev. (DSM-III-R) and The Diagnostic and Statistical Manual of Mental Disorders, 4th ed. (DSM-IV) classified BDD's nondelusional form in the somatoform section of the manual and its delusional form in the psychosis section, as a type of delusional disorder, somatic type (although DSM-IV allowed double-coding of delusional BDD as both a psychotic disorder and BDD). However, little or no evidence on this issue was available when these editions were published. In this article, we review the classification of BDD's delusional and nondelusional variants in earlier editions of DSM and the limitations of their approaches. We then review empirical evidence on this topic, which has become available since DSM-IV was developed. Available evidence indicates that across a range of validators, BDD's delusional and nondelusional variants have many more similarities than differences, including response to pharmacotherapy. Based on these data, we propose that BDD's delusional and nondelusional forms be classified as the same disorder and that BDD's diagnostic criteria include an insight specifier that spans a range of insight, including absent insight/delusional BDD beliefs. We hope that this recommendation will improve care for patients with this common and often-severe disorder. This increased understanding of BDD may also have implications for other disorders that have an “absent insight/delusional” form.
Global Reuse and optimal waste policy
Authors: Yokoo Hide-Fumi , Kinnaman Thomas C.
Published: May 2013

Electronic waste generated from the consumption of durable goods in developed countries is often exported to underdeveloped countries for reuse, recycling and disposal with unfortunate environmental consequences. The lack of efficient disposal policies within developing nations coupled with global free trade agreements make it difficult for consumers to internalize these costs. This paper develops a two-country model, one economically developed and the other underdeveloped, to solve for optimal tax policies necessary to achieve the efficient allocation of economic resources in an economy with a durable good available for global reuse without policy measures in the underdeveloped country. A tax in the developed country on purchases of the new durable good combined with a waste tax set below the domestic external cost of disposal is sufficient for global efficiency. The implication of allowing free global trade in electronic waste is also examined, where optimal policy resembles a global deposit-refund system.
Managing rainwater, improving livelihoods: assessing impacts using a Rainwater–Livelihoods–Poverty Index (RLPI)
Authors: Getnet Kindie , Kefyalew Geremew
Published: May 2013

Assessing and empirically measuring the development impact of rainwater management innovations to inform related decisions remains conceptually and methodologically difficult. Whether it is empirically more appropriate to assess and measure the impact pathways than the impact per se remains an important methodological issue. This paper proposes a Rainwater–Livelihoods–Poverty Index (RLPI) as a comprehensive and participatory impact pathway assessment technique with measurable indicators recapitulating the sustainable livelihoods framework. The methodological contributions to rainwater impact assessment are two-fold. First, the RLPI explicitly incorporates intermediate processes and impact pathways as important factors affecting the development impacts of rainwater-related interventions. Second, the RLPI combines quantitative and qualitative household response data into a single yet meaningful quantitative impact indicator. This makes the methodology participatory, allowing farmers engagement to use their knowledge (as local expert observers) in informing rainwater management decisions. The methodology is empirically tested in Diga district (western Ethiopia) and validated using expert opinions.
Program sustainability and the determinants of farmers’ self-predicted post-program land use decisions: evidence from the Sloping Land Conversion Program (SLCP) in China
Authors: Yang Xiaojun , Xu Jintao
Published: May 2013

In this paper we evaluate the long-run sustainability of China's Sloping Land Conversion Program (SLCP) by investigating the determinants of farmers’ self-predicted post-program land use decisions. We use data from a household survey conducted in 2005, with a particular focus on a dependent variable that reflects farmers’ ordinal responses to a question about their probability of converting the enrolled lands back to cultivation after the program ends. First, we find that targeting the program on steeper sloped and lower quality plots can significantly decrease the probability of reconversion. Second, there is a significant and robust household income structure effect on the reconversion probability. Third, participating households with the right to decide what to plant on enrolled land have a higher probability of maintaining the reforested land after the program ends. Finally, subsidy shortfall has a positive influence on the probability of reconversion.
Mortality in Ireland 1901 to 2006
Authors: Hall M.
Published: May 2013

Over the course of the 20th century Ireland moved from being a largely young population with a high death rate from infectious diseases to an increasingly older population with a consequent rise in chronic diseases. Understanding the changes that occurred in Irish mortality over the 20th century and how these changes compare with those experienced by similar countries can help us plan for the challenges of our aging population. This paper analyses trends in mortality in Ireland over the period 1901 to 2006 by age group, gender and five broad categories of cause of death – infectious diseases, circulatory diseases, respiratory diseases, cancer and external causes. To place the changes in an international context the trends are compared with those experienced by Northern Ireland and England and Wales. Ireland experienced the fastest improvements in mortality of the three regions in the early years of the 21st century. By 2006 the mortality of Irish males ranked between that of Northern Ireland and England and Wales while Irish females experienced the lowest mortality of the three regions. The improvement in Irish mortality in the 21st century can be attributed mainly to the drop in deaths from circulatory diseases for both males and females.
The impact of the food-based and nutrient-based standards on lunchtime food and drink provision and consumption in secondary schools in England
Authors: Nicholas Jo , Wood Lesley , Harper Clare , Nelson Michael
Published: May 2013

Objectives

To assess lunchtime provision of food and drink in English secondary schools and the choices and consumption of food and drink by pupils having school lunches, and to compare provision in 2011 with that in 2004.

Design

Cross-sectional data collected between October 2010 and April 2011. In each school, food and drink provision, including portion weights and number of portions of each item served at lunchtime, were recorded over five consecutive days. Caterers provided recipe information.

Setting

England.

Subjects

A random selection of 5969 pupils having school lunches in a nationally representative sample of eighty secondary schools in England.

Results

Compared with 2004, significantly more schools in 2011 provided main dishes, vegetables and salads, water, fruit juice and other drinks on 4 or 5 d/week (P < 0·005). The number of schools offering items not permitted under the food-based standards for school food on 4 or 5 d/week fell significantly over time (P < 0·005), while the number not offering these items on any day increased significantly (P < 0·005). Meals eaten by pupils were well-balanced in relation to macronutrients.

Conclusions

Lunchtime food provision and consumption in secondary schools have improved considerably since 2004, following the introduction of new compulsory standards for school food in 2009. To maximise their energy and nutrient intake at lunchtime, pupils should be encouraged to select a full meal, and to take and eat more fruit and vegetables. Schools also need continued support to increase the micronutrient content of menus and recipes.
Introduction to Special Issue: Japan's Crisis Management amid Growing Complexity: In Search of New Approaches
Authors: SAKAKI ALEXANDRA , LUKNER KERSTIN
Published: May 2013

The 3/11 triple disaster, comprising the powerful earthquake, devastating tsunami, and nuclear meltdowns at the Fukushima nuclear power complex, has drawn worldwide attention to Japan's crisis management capabilities. This article lays out key concepts used in analyzing crises and addresses major trends in contemporary crisis management endeavors. It then turns to the Japanese case, identifying six key themes in the debates about the country's crisis management capabilities. In tracing and exploring past reform efforts, the article assesses characteristics and highlights perceived deficiencies in Japan's approach. The final part provides a brief overview of the case studies presented in this special issue, pinpointing recurrent themes and enduring problems observed in recent crisis management efforts.
Crisis Management, LDP, and DPJ Style
Authors: KRAUSS ELLIS
Published: May 2013

This article asks the questions: Did the DPJ engage in crisis response and management differently than the LDP did? If so, why? If not, why not? In order to try to answer these questions systematically I use an inductive comparative method of choosing three equivalent ‘cases’ each under the LDP and the DPJ in which they responded to a similar type of crisis. The crises selected were Okinawa bases issues in 1995 (LDP) and 2009 (DPJ), Senkaku Islands under the LDP (2008) and DPJ (2010), and the Hanshin quake in 1995 (LDP) and Fukushima in 2011 (DPJ). This gave me a nice mix of intense, short-term cases to compare; one domestic (disaster-related), and two foreign (Okinawa bases with US; Senkaku/Daiyou conflict with China); coalition governments under LDP and DPJ (2009) of different kinds vs. single-party (other DPJ). A very brief description of each crisis will be followed by some generalizations comparing the two parties’ responses. I find that both parties had similar problems with information management, but that there were characteristic and predictable trade-offs of their different party decisionmaking structures and relations with the national bureaucracy. Finally, I mention some of the inherent structural problems of Japanese politics and policymaking that inhibit effective response regardless of the party in power.
The Crisis Management Capability of Japan's Self Defense Forces for UN Peacekeeping, Counter-Terrorism, and Disaster Relief
Authors: ISHIZUKA KATSUMI
Published: May 2013

This article examines the crisis management capabilities of Japan's Self Defense Forces (SDF) in the areas of United Nations (UN) peacekeeping, counter-terrorism, and disaster relief. The three types of overseas operations were all initiated by Japan as a response to international crises. While SDF crisis management capabilities for UN peacekeeping operations have steadily evolved, room for improvement remains. For example, Japan's commitment to logistic and rapid deployment missions could be strengthened. Regarding the second type of operations, counter-terrorism, Japan's crisis management capabilities were enhanced by the passing of a novel Anti-Terrorism Law in October 2001 after the 9/11 attacks. The law legalized a SDF oil-fuelling mission in the Indian Ocean in support of the US-led war on terror in Afghanistan. Compared to the first two types of missions, SDF crisis management capabilities in disaster relief are the least controversial. This is due to the nature of the SDF as politically neutral and their humanitarian and non-military activities. This article highlights and compares the strengths and weaknesses of Japan's capabilities in the three types of SDF overseas operations. It demonstrates that a number of problem areas remain, including the need for legal amendment as well as the enhancement of public support and political consensus. The Japanese government and the SDF should face up to these challenges so that Japan can become better positioned to react quickly to crisis situations that require the dispatch of the SDF.
Financial Crisis Fatigue? Politics behind Japan's Post-Global Financial Crisis Economic Contraction
Authors: KATADA SAORI N.
Published: May 2013

Despite a relatively healthy financial sector, the Japanese economy contracted 6.3% in 2009 during the global financial crisis (GFC) after the Lehman shock, the starkest drop among the OECD countries. Since then, the Japanese economy has been slow to recover, although the Japanese government has implemented multiple economic stimulus packages with a high aggregate value.

By tracing the Japanese government's response to the GFC in the critical months of October 2008 through the end of 2009, this study argues that the Japanese government failed to manage the crisis decisively due to institutional constraints derived, ironically, from the experiences that Japan gained from a series of financial crises in the 1990s and 2000s. Financial crisis fatigue constrained the supply of Japan's fiscal and monetary measures against the GFC and slowed political response. Furthermore, it made Japanese society unresponsive to these measures.
DPJ's Political Leadership in Response to the Fukushima Nuclear Accident
Authors: SHINODA TOMOHITO
Published: May 2013

The 11 March 2011 earthquake and tsunami damaged the nuclear reactors in Fukushima. Prime Minister Naoto Kan took this crisis seriously, and made himself personally involved with damage control, especially during the first week. This study examines the responses to the incident by the prime minister's office.

Universal wisdom is that crises are better handled at the level closest to which they occur. Shifting the decision making to the higher authority is needed when a crisis spills over the local boundary or when the local authority fails to deal with the situation. This is called ‘upscaling’.

Frustrated by the lack of communication coming from the bureaucracy and Tokyo Electric Power Company (TEPCO), Kan upscaled the decision making and began micromanaging damage control. The upscaling, however, did not contribute to improvement in the accident situation in most cases. Even in one case, it exacerbated it.

On the other hand, upscaling made a significant difference when the TEPCO officials considered withdrawing from the accident. By upscaling to the higher authority, Kan stopped their withdrawal. After the establishment of a joint headquarters with TEPCO, the political leaders, instead of upscaling, moved down to a closer level to the accident and successfully coordinated the recovery work.
A separate structured conversation with relatives of patients enrolled for advanced palliative home care: A care development project
Authors: Carlsson Maria E.
Published: May 2013

Objective:

One prerequisite for palliative home care is the relatives' participation in the care. The relatives' situation in palliative home care is unique, as they support the sick person and also have a great need for support themselves. The aim of this care development project was to develop and implement separate structured conversations (SSC) with relatives of patients of an advanced palliative home care team (APHCT).

Method:

During the project, 61 conversations were held and 55 relatives answered a questionnaire. The questionnaire, eight semistructured interviews with relatives, and three focus-group discussions with nurses constitute the material for the evaluation.

Results:

Relatives have difficulties separating the SSC from the APHCT's care as a whole. They underline that the SSC was a part of an ongoing process. They also emphasize the value of having a conversation of their own in which the patient was absent, and in which the focus was on the relative's situation. For some, the conversation took place at the APHCT premises. The advantages of that were more privacy and the opportunity to walk around the inpatient palliative care units. The main problem during the project was conducting the SSC soon after the patient was enrolled with the APHCT.

Significance of results:

Routinely offering one separate structured conversation with relatives with the intention of answering questions, talking about their willingness to provide care in the home, and mapping out their situation and social network, is a way to support both the relatives and the patients. The common structure of the conversations facilitated the assessment of the relatives' situation but did not hinder individualization according to the relatives' needs. The assumption is that all relatives should be offered a conversation.
Breathlessness in everyday life from a patient perspective: A qualitative study using diaries
Authors: Ahmadi Nasser S. , Månsson Jörgen , Lindblad Ulf , Hildingh Cathrine
Published: May 2013

Objective:

Breathlessness is a subjective symptom, which makes it difficult to define and understand. The aim of the present study was to illuminate how patients suffering from breathlessness experience their everyday life.

Method:

The study was a qualitative study, and the focus of the analysis was the patients' descriptions of their experiences of breathlessness using a diary with two unstructured questions for a period of 7 consecutive days. Sixteen participants: 7 men, mean age 65 ± 7 (range 55–73 years old), and 9 women, mean age 65 ± 9 (range 50–72 years old) participated in the study.

Results:

Two themes emerged from the analysis: 1) Impaired quality of life and 2) symptom tolerance and adaptation. The theme “impaired quality of life” included the categories limited physical ability, psychological burdens, and social life barriers. The theme “symptom tolerance and adaptation” included importance of health care, social support, hobbies and leisure activities, and coping strategies.

Significance of results:

The findings in our study showed that patients, in spite of considerable difficulties with shortness of breath, found relief in several types of activities, in addition to drug therapy. The result indicates that the “biopsychosocial model” is an appealing approach that should be discussed further to gain a better understanding of breathlessness.
Hospitalization in Adolescence and Young Adulthood Among Twins and Singletons: A Swedish Cohort Study of Subjects Born Between 1973 and 1983
Authors: Bladh Marie , Carstensen John , Josefsson Ann , Finnström Orvar , Sydsjö Gunilla
Published: May 2013

Children born with non-optimal birth characteristics — that is, are small for gestational age and/or preterm — have an increased risk for several long-term effects such as neurological sequelae and chronic disease. The purpose of this study was to examine whether twins exhibited a different outcome, compared with singletons, in terms of hospitalization during adolescence and early adulthood, and to what extent differences remain when considering the divergence in birth characteristics between singletons and twins. Persons born between 1973 and 1983 in Sweden and surviving until age 13 were included and followed until the end of 2006. Data on birth characteristics, parental socio-demographic factors, and hospitalizations were collected from national registers. Adjusting for parental socio-demographic factors, twins had a higher risk of being hospitalized than singletons (odds ratio, OR = 1.17, 95% confidence interval, CI = 1.10–1.25) and more often due to ‘Congenital anomalies’ (OR = 1.18, 95% CI = 1.06–1.28), ‘Infections’ (OR = 1.14; 95% CI = 1.08–1.20), ‘External causes of illness’ (OR = 1.10, 95% CI = 1.06–1.15), and ‘Diseases of the nervous system’ (OR = 1.18, 95% CI = 1.10–1.26). Stratifying for birth characteristics, this difference diminishes, and for some diagnoses non-optimal twins seem to do slightly better than non-optimal singletons. Thus, twins with non-optimal birth characteristics had a lower risk of hospitalization than non-optimal singletons on, for example, ‘Congenital anomalies’ and ‘Diseases of the nervous system’ (OR = 0.86, 95% CI = 0.77–0.96; OR = 0.88, 95% CI = 0.81–0.97, respectively) and Total (any) hospitalization (OR = 0.87, 95% CI = 0.83–0.92). Among those with optimal birth characteristics, twins had an increased hospitalization due to ‘External causes of illness’ (OR = 1.07, 95% CI = 1.02–1.13) compared with optimal singletons. Twins have higher hospitalization rates than singletons. In stratifying for birth characteristics, this difference diminishes, and for some diagnoses, non-optimal twins seem to do less poorly than non-optimal singletons.
The paradox of elongation factor 4: highly conserved, yet of no physiological significance?
Authors: Zhang Dejiu , Qin Yan
Published: May 2013

LepA [EF4 (elongation factor 4)] is a highly conserved protein found in nearly all known genomes. EF4 triggers back-translocation of the elongating ribosome, causing the translation machinery to move one codon backwards along the mRNA. Knockout of the corresponding gene in various bacteria results in different phenotypes; however, the physiological function of the factor in vivo is unclear. Although functional research on Guf1 (GTPase of unknown function 1), the eukaryotic homologue of EF4, showed that it plays a critical role under suboptimal translation conditions in vivo, its detailed mechanism has yet to be identified. In the present review we briefly cover recent advances in our understanding of EF4, including in vitro structural and biochemical studies, and research on its physiological role in vivo. Lastly, we present a hypothesis for back-translocation and discuss the directions future EF4 research should focus on.
Evidence for novel aspects of Nox4 oxidase regulation of mitochondrial function and peroxide generation in an endothelial cell model of senescence
Authors: Wolin Michael S.
Published: May 2013

Observations by Kozieł et al. reported in this issue of the Biochemical Journal suggest the existence of novel regulatory processes associated with new evidence for increased Nox4 (NAPDH oxidase 4) regulation of mitochondrial function in a cultured endothelial cell aging-induced senescence model. Cellular aging appears to promote a Nox4 interaction with mitochondria that disrupts complex I in the electron transport chain and increases the detection of mitochondrial H2O2. Nox4 appears to maintain a highly interconnected mitochondrial network, which may influence mitochondrial fission and/or fusion mechanisms in a manner that could be a contributing factor in the loss of replicative lifespan seen in senescence.
Reactive centre loop mutants of α-1-antitrypsin reveal position-specific effects on intermediate formation along the polymerization pathway
Authors: Haq Imran , Irving James A. , Faull Sarah V. , Dickens Jennifer A. , Ordóñez Adriana , Belorgey Didier , Gooptu Bibek , Lomas David A.
Published: May 2013

The common severe Z mutation (E342K) of α1-antitrypsin forms intracellular polymers that are associated with liver cirrhosis. The native fold of this protein is well-established and models have been proposed from crystallographic and biophysical data for the stable inter-molecular configuration that terminates the polymerization pathway. Despite these molecular ‘snapshots’, the details of the transition between monomer and polymer remain only partially understood. We surveyed the RCL (reactive centre loop) of α1-antitrypsin to identify sites important for progression, through intermediate states, to polymer. Mutations at P14P12 and P4, but not P10P8 or P2P1′, resulted in a decrease in detectable polymer in a cell model that recapitulates the intracellular polymerization of the Z variant, consistent with polymerization from a near-native conformation. We have developed a FRET (Förster resonance energy transfer)-based assay to monitor polymerization in small sample volumes. An in vitro assessment revealed the position-specific effects on the unimolecular and multimolecular phases of polymerization: the P14P12 region self-inserts early during activation, while the interaction between P6P4 and β-sheet A presents a kinetic barrier late in the polymerization pathway. Correspondingly, mutations at P6P4, but not P14P12, yield an increase in the overall apparent activation energy of association from ~360 to 550 kJ mol−1.
Quantification of trap state densities in GaAs heterostructures grown at varying rates using intensity-dependent time resolved photoluminescence
Authors: Haughn C. R. , Schmieder K. J. , Zide J. M. O. , Barnett A. , Ebert C. , Opila R. , Doty M. F.
Published: May 2013

Time-resolved photoluminescence is an established technique for characterizing carrier lifetimes in semiconductors, but the dependence of lifetime on excitation fluence has been only qualitatively investigated. We develop a quantitative approach for fitting fluence-dependent PL decay data to a Shockely-Read-Hall model of carrier recombination in order to extract the trap state density. We demonstrate this approach by investigating growth rate-dependent trap densities in gallium arsenide-indium gallium phosphide double heterostructures. The techniques developed here can be applied for rapid, non-destructive quantification of trap state densities in a variety of materials.
Multiplets at zero magnetic field: The geometry of zero-field NMR
Authors: Butler Mark C. , Ledbetter Micah P. , Theis Thomas , Blanchard John W. , Budker Dmitry , Pines Alexander
Published: May 2013

For liquid samples at Earth's field or below, nuclear-spin motion within scalar-coupled networks yields multiplets as a spectroscopic signature. In weak fields, the structure of the multiplets depends on the magnitude of the Zeeman interaction relative to the scalar couplings; in Earth's field, for example, heteronuclear couplings are truncated by fast precession at distinct Larmor frequencies. At zero field, weak scalar couplings are truncated by the relatively fast evolution associated with strong scalar couplings, and the truncated interactions can be described geometrically. When the spin system contains a strongly coupled subsystem A, an average over the fast evolution occurring within the subsystem projects each strongly coupled spin onto FA, the summed angular momentum of the spins in A. Weakly coupled spins effectively interact with FA, and the coupling constants for the truncated interactions are found by evaluating projections. We provide a formal description of zero-field spin systems with truncated scalar couplings while also emphasizing visualization based on a geometric model. The theoretical results are in good agreement with experimental spectra that exhibit second-order shifts and splittings.
Ag-Cu catalysts for ethylene epoxidation: Selectivity and activity descriptors
Authors: Nguyen Ngoc Linh , de Gironcoli Stefano , Piccinin Simone
Published: May 2013

Ag-Cu alloy catalysts for ethylene epoxidation have been shown to yield higher selectivity towards ethylene oxide compared to pure Ag, the unique catalyst employed in the industrial process. Previous studies showed that under oxidizing conditions Cu forms oxide layers on top of Ag. Using first-principles atomistic simulations based on density functional theory, we investigate the reaction mechanism on the thin oxide layer structures and establish the reasons for the improved selectivity. We extend the range of applicability of the selectivity descriptor proposed by Kokalj et al. [J. Catal. 254, 304 (2008)]10.1016/j.jcat.2008.01.008, based on binding energies of reactants, intermediates, and products, by refitting its parameters so as to include thin oxide layer catalysts. We show that the selectivity is mainly controlled by the relative strength of the metal-carbon vs. metal-oxygen bonds, while the height of the reaction barriers mostly depend on the binding energy of the common oxametallacycle intermediate.
An analytical continuation approach for evaluating emission lineshapes of molecular aggregates and the adequacy of multichromophoric Förster theory
Authors: Banchi Leonardo , Costagliola Gianluca , Ishizaki Akihito , Giorda Paolo
Published: May 2013

In large photosynthetic chromophore-protein complexes not all chromophores are coupled strongly, and thus the situation is well described by formation of delocalized states in certain domains of strongly coupled chromophores. In order to describe excitation energy transfer among different domains without performing extensive numerical calculations, one of the most popular techniques is a generalization of Förster theory to multichromophoric aggregates (generalized Förster theory) proposed by Sumi [J. Phys. Chem. B 103, 252 (1999)10.1021/jp983477u] and Scholes and Fleming [J. Phys. Chem. B 104, 1854 (2000)10.1021/jp993435l]. The aim of this paper is twofold. In the first place, by means of analytic continuation and a time convolutionless quantum master equation approach, a theory of emission lineshape of multichromophoric systems or molecular aggregates is proposed. In the second place, a comprehensive framework that allows for a clear, compact, and effective study of the multichromophoric approach in the full general version proposed by Jang, Newton, and Silbey [Phys. Rev. Lett. 92, 218301 (2004)10.1103/PhysRevLett.92.218301] is developed. We apply the present theory to simple paradigmatic systems and we show on one hand the effectiveness of time-convolutionless techniques in deriving lineshape operators and on the other hand we show how the multichromophoric approach can give significant improvements in the determination of energy transfer rates in particular when the systems under study are not the purely Förster regime. The presented scheme allows for an effective implementation of the multichromophoric Förster approach which may be of use for simulating energy transfer dynamics in large photosynthetic aggregates, for which massive computational resources are usually required. Furthermore, our method allows for a systematic comparison of multichromophoric Föster and generalized Förster theories and for a clear understanding of their respective limits of validity.
High-temperature neutron diffraction and first-principles study of temperature-dependent crystal structures and atomic vibrations in Ti3AlC2, Ti2AlC, and Ti5Al2C3
Authors: Lane Nina J. , Vogel Sven C. , Caspi El'ad N. , Barsoum Michel W.
Published: May 2013

Herein we report on the thermal expansions and temperature-dependent crystal structures of select ternary carbide Mn+1AXn (MAX) phases in the Ti–Al–C phase diagram in the 100−1000 °C temperature range. A bulk sample containing 38(±1) wt. % Ti5Al2C3 (“523”), 32(±1) wt. % Ti2AlC (“211”), 18(±1) wt. % Ti3AlC2 (“312”), and 12(±1) wt. % (Ti0.5Al0.5)Al is studied by Rietveld analysis of high-temperature neutron diffraction data. We also report on the same for a single-phase sample of Ti3AlC2 for comparison. The thermal expansions of all the MAX phases studied are higher in the c direction than in the a direction. The bulk expansion coefficients—9.3(±0.1)×10−6 K−1 for Ti5Al2C3, 9.2(±0.1) ×10−6 K−1 for Ti2AlC, and 9.0(±0.1)×10−6 K−1 for Ti3AlC2—are comparable within one standard deviation of each other. In Ti5Al2C3, the dimensions of the Ti–C octahedra for the 211-like and 312-like regions are comparable to the Ti–C octahedra in Ti2AlC and Ti3AlC2, respectively. The isotropic mean-squared atomic displacement parameters are highest for the Al atoms in all three phases, and the values predicted from first-principles phonon calculations agree well with those measured.
Scattering of radio frequency waves by blobs in tokamak plasmas
Authors: Ram Abhay K. , Hizanidis Kyriakos , Kominis Yannis
Published: May 2013

The density fluctuations and blobs present in the edge region of magnetic fusion devices can scatter radio frequency (RF) waves through refraction, reflection, diffraction, and coupling to other plasma waves. This, in turn, affects the spectrum of the RF waves and the electromagnetic power that reaches the core of the plasma. The usual geometric optics analysis of RF scattering by density blobs accounts for only refractive effects. It is valid when the amplitude of the fluctuations is small, of the order of 10%, compared to the background density. In experiments, density fluctuations with much larger amplitudes are routinely observed, so that a more general treatment of the scattering process is needed. In this paper, a full-wave model for the scattering of RF waves by a blob is developed. The full-wave approach extends the range of validity well beyond that of geometric optics; however, it is theoretically and computationally much more challenging. The theoretical procedure, although similar to that followed for the Mie solution of Maxwell's equations, is generalized to plasmas in a magnetic field. Besides diffraction and reflection, the model includes coupling to a different plasma wave than the one imposed by the external antenna structure. In the model, it is assumed that the RF waves interact with a spherical blob. The plasma inside and around the blob is cold, homogeneous, and imbedded in a uniform magnetic field. After formulating the complete analytical theory, the effect of the blob on short wavelength electron cyclotron waves and longer wavelength lower hybrid waves is studied numerically.
Ag dendritic nanostructures as ultrastable substrates for surface-enhanced Raman scattering
Authors: Fei Chan Yu , Xing Zhang Chang , Long Wu Zheng , Mei Zhao Dan , Wang Wei , Jun Xu Hai , Sun Xiao Ming
Published: May 2013

Dendritic silver nanostructures coated with silica nanofilm are synthesized via hydrothermal etching using silver nitrate, hydrofluoric acid, and hydrogen peroxide and controlling the reagent concentration, reaction time, and temperature. The silver dendritic nanostructures are employed as substrates for surface-enhanced Raman scattering (SERS) and exhibit high sensitivity and excellent stability. Calibration of the Raman peak intensities of rhodamine 6G and thiram allowed quantitative detection of these organic molecules. Our findings are a significant advance in developing robust SERS substrates for fast detection of trace organic contaminants.
Asymmetric superconducting quantum interference devices for suppression of phase diffusion in small Josephson junctions
Authors: Sullivan D. F. , Dutta S. K. , Dreyer M. , Gubrud M. A. , Roychowdhury A. , Anderson J. R. , Lobb C. J. , Wellstood F. C.
Published: May 2013

We have measured the switching current versus applied magnetic flux of a highly asymmetric, hysteretic dc superconducting quantum interference device (SQUID) from 30 mK to 400 mK. The SQUID loop had an inductance of 1 nH, and the capacitances of the two Al-Al2O3-Al Josephson junctions comprising the SQUID were 100 fF and 5 fF. As expected, the switching current of the SQUID displayed a small, periodic modulation with applied flux, from which the switching currents of the large and small junctions at 30 mK were determined to be 846.3 ± 0.1 nA and 0.7 ± 0.08 nA, respectively. Measurements of an identically prepared small junction exhibited a highly suppressed switching current (IS < 10 pA), consistent with phase diffusion in this device. The observed modulation in the SQUID thus demonstrates that the quantum mechanical uncertainty in the phase difference across the small junction was significantly reduced by coupling to the large junction through the loop inductance. We discuss the sensitivity of this technique for determining the gauge-invariant phase difference of small Josephson junctions, and the implications for imaging the phase of superconductors at the atomic scale using scanning tunneling microscopy.
Averaged equation for energy diffusion on a graph reveals bifurcation diagram and thermally assisted reversal times in spin-torque driven nanomagnets
Authors: Newhall Katherine A. , Vanden-Eijnden Eric
Published: May 2013

Driving nanomagnets by spin-polarized currents offers exciting prospects in magnetoelectronics, but the response of the magnets to such currents remains poorly understood. We show that an averaged equation describing the diffusion of energy on a graph captures the low-damping dynamics of these systems. From this equation we obtain the bifurcation diagram of the magnets, including the critical currents to induce stable precessional states and magnetization switching, as well as the mean times of thermally assisted magnetization reversal in situations where the standard reaction rate theory of Kramers is no longer valid. These results match experimental observations and give a theoretical basis for a Néel-Brown-type formula with an effective energy barrier for the reversal times.
Phase transition behavior and electrical properties of lead-free (Ba1−xCax)(Zr0.1Ti0.9)O3 piezoelectric ceramics
Authors: Tian Ye , Chao Xiaolian , Wei Lingling , Liang Pengfei , Yang Zupei
Published: May 2013

Lead-free (Ba1−xCax)(Zr0.1Ti0.9)O3(BCZT) ceramics were synthesized by conventional solid-state sintering process. The Ca ion substitutions on phase transition behavior, microstructure, ferroelectric and piezoelectric properties of BCZT ceramics were systemically investigated. The diffuse phase transition (DPT) behavior was suppressed, while the orthorhombic → tetragonal (O→T) and rhombohedral → orthorhombic (R→O) phase transitions were observed when the Ca content is at x = 0.05. Further increasing the Ca content, the DPT behavior gradually enhanced, and both the O→T and R→O phase transitions gradually evolved into R→T phase transition when the Ca content increases up to 0.15 at 25 °C. This behavior was related with phase structure and morphology, which significantly impacted the ferroelectric and piezoelectric properties near the R→T phase boundary. As a result, the sample with Ca contents of 0.15 shows the outstanding piezoelectric properties (with d33 = 572 pC/N, kp = 57%, Qm = 125, εr = 4821, and tan δ = 0.015) while negligible change for the ferroelectric properties. The abnormal ferroelectric behavior and potential factor contributing to large piezoelectric response also were discussed.