bluuebunny/crossref_metadata_2025 huggingface dataset:
Limit theorems for decomposable branching processes in a random environment
Authors: Vatutin Vladimir , Liu Quansheng
Published: March 2016

We study the asymptotics of the survival probability for the critical and decomposable branching processes in a random environment and prove Yaglom-type limit theorems for these processes. It is shown that such processes possess some properties having no analogues for the decomposable branching processes in a constant environment.
In Defense of Tasks and TBLT: Nonissues and Real Issues
Authors: Long Michael H.
Published: March 2016

The first aim of this article, addressed in section 1, is to define what is meant, and not meant, by task and task-based language teaching (TBLT). The second is to summarize and evaluate 14 criticisms that have been made of both. Section 2 responds to five alleged problems with TBLT's psycholinguistic rationale, section 3 to six at the classroom level, and section 4 to three claimed problems with implementing TBLT in specific contexts. A few of the criticisms touch on important matters, but most, I will suggest, are nonissues. The third aim of the article is to identify some genuine problems in need of resolution—real issues—and briefly to illustrate research programs under way to address them.
The Role of Teachers in Task-Based Language Education
Authors: Van den Branden Kris
Published: March 2016

Both in the research literature on tasks and second language learning and in the pedagogical literature on task-based language teaching (TBLT), the role of the teacher has received scant attention. In this article, the role of the teacher in TBLT is approached from three perspectives: (a) the teacher as mediator of the students’ language development, contributing to the effectiveness of TBLT as a pedagogical approach to second language education; (b) the teacher as a key figure in the implementation of TBLT, and thus as a change agent in the innovation of second language education; and (c) the teacher as researcher, and thus as an active contributor to the development and further refinement of TBLT as a researched pedagogy.
Exploring Engagement in Tasks in the Language Classroom
Authors: Philp Jenefer , Duchesne Susan
Published: March 2016

This article explores how learners engage in tasks in the context of language classrooms. We describe engagement as a multidimensional construct that includes cognitive, behavioral, social, and emotional dimensions of engagement among second and foreign language learners in the classroom. We discuss key concepts and indicators of engagement in current research on task-based interaction and outline some of the issues in researching engagement in this context.
Tasks Versus Conditions: Two Perspectives on Task Research and Their Implications for Pedagogy
Authors: Skehan Peter
Published: March 2016

This chapter explores the contrast between the effects on second language performance of tasks and task characteristics, on the one hand, and the conditions under which tasks are done, on the other. The first major section explores the evidence on this issue and proposes that the impact of conditions such as pretask planning, task repetition, and posttask activities is greater and more consistent than the impact of tasks and features such as time perspective or number of elements. The second major section explores the theoretical accounts that have been proposed regarding tasks and conditions. It is suggested that deductive accounts have, so far, only had limited success regarding the use of tasks, but that psycholinguistic models of speaking do provide a looser but more useful framework to account for the effects of conditions. It is also suggested that an important difference between tasks and conditions concerns the tension between constraint and flexibility in performance and that the flexibility provided by task conditions is an important component in the more dependable results they have generated. Finally, pedagogic implications are discussed linking task conditions to the methodological choices that are available to teachers.
Teachers’ Perspectives on Second Language Task Difficulty: Insights From Think-Alouds and Eye Tracking
Authors: Révész Andrea , Gurzynski-Weiss Laura
Published: March 2016

The majority of empirical studies that have so far investigated task features in order to inform task grading and sequencing decisions have been grounded in hypothesis-testing research. Few studies have attempted to adopt a bottom-up approach in order to explore what task factors might contribute to task difficulty. The aim of this study was to help fill this gap by eliciting teachers’ perspectives on sources of task difficulty. We asked 16 English as a second language (ESL) teachers to judge the linguistic ability required to carry out four pedagogic tasks and consider how they would manipulate the tasks to suit the abilities of learners at lower and higher proficiency. While contemplating the tasks, the teachers thought aloud, and we also tracked their eye movements. The majority of teachers’ think-aloud comments revealed that they were primarily concerned with linguistic factors when assessing task difficulty. Conceptual demands were most frequently proposed as a way to increase task difficulty, whereas both linguistic and conceptual factors were suggested by teachers when considering modifications to decrease task difficulty. The eye-movement data, overall, were aligned with the teachers’ think-aloud comments. These findings are discussed with respect to existing task taxonomies and future research directions.
Task-Based Learner Production: A Substantive and Methodological Review
Authors: Plonsky Luke , Kim YouJin
Published: March 2016

Tasks are frequently used to elicit learner language in second language (L2) research. The purposes for doing so, however, vary widely, covering a range of theoretical models, designs, and analyses. For example, task-based researchers have examined a range of linguistic and interactional features (e.g., accuracy, language-related episodes) that are found in learner production and that vary as a function of task conditions (e.g., +/− complex), modes (oral, written, computer-mediated), and settings (second vs. foreign language). This article presents a synthesis of substantive interests and methodological practices in this area. We first collected a sample of 85 primary studies of task-based language production published from 2006 to 2015. Each study was then coded for the target features it analyzed as well as other contextual and demographic variables. We also coded for methodological features related to study designs, sampling, analyses, and reporting practices. The results indicate a strong preference toward analyses of grammar, vocabulary, accuracy, and different features of L2 interaction, and very little interest in task-induced pronunciation, pragmatics, and the quality of task performance. More fundamentally, this domain may be hindered by a lack of theoretical and operational consistency. The data also point to a number of concerns related to research and reporting practices (e.g., low statistical power; missing data). Based on our findings, we outline a number of pointed recommendations for future research in this domain.
The Early Chain of Care in Patients with Bacteraemia with the Emphasis on the Prehospital Setting
Authors: Axelsson Christer , Herlitz Johan , Karlsson Anders , Sjöberg Henrik , Jiménez-Herrera Maria , Bång Angela , Jonsson Anders , Bremer Anders , Andersson Henrik , Gellerstedt Martin , Ljungström Lars
Published: March 2016

Purpose

There is a lack of knowledge about the early phase of severe infection. This report describes the early chain of care in bacteraemia as follows: (a) compare patients who were and were not transported by the Emergency Medical Services (EMS); (b) describe various aspects of the EMS chain; and (c) describe factors of importance for the delay to the start of intravenous antibiotics. It was hypothesized that, for patients with suspected sepsis judged by the EMS clinician, the delay until the onset of antibiotic treatment would be shorter.

Basic Procedures

All patients in the Municipality of Gothenburg (Sweden) with a positive blood culture, when assessed at the Laboratory of Bacteriology in the Municipality of Gothenburg, from February 1 through April 30, 2012 took part in the survey.

Main Findings/Results

In all, 696 patients fulfilled the inclusion criteria. Their mean age was 76 years and 52% were men. Of all patients, 308 (44%) had been in contact with the EMS and/or the emergency department (ED). Of these 308 patients, 232 (75%) were transported by the EMS and 188 (61%) had “true pathogens” in blood cultures. Patients who were transported by the EMS were older, included more men, and suffered from more severe symptoms and signs.

The EMS nurse suspected sepsis in only six percent of the cases. These patients had a delay from arrival at hospital until the start of antibiotics of one hour and 19 minutes versus three hours and 21 minutes among the remaining patients (P =.0006). The corresponding figures for cases with “true pathogens” were one hour and 19 minutes versus three hours and 15 minutes (P =.009).

Conclusion

Among patients with bacteraemia, 75% used the EMS, and these patients were older, included more men, and suffered from more severe symptoms and signs. The EMS nurse suspected sepsis in six percent of cases. Regardless of whether or not patients with true pathogens were isolated, a suspicion of sepsis by the EMS clinician at the scene was associated with a shorter delay to the start of antibiotic treatment.

AxelssonC, HerlitzJ, KarlssonA, SjöbergH, Jiménez-HerreraM, BångA, JonssonA, BremerA, AnderssonH, GellerstedtM, LjungströmL. The early chain of care in patients with bacteraemia with the emphasis on the prehospital setting. Prehosp Disaster Med. 2016;31(3):272–277.
Serum Brain-Derived Neurotrophic Factor Mediates the Relationship between Abdominal Adiposity and Executive Function in Middle Age
Authors: Kaur Sonya , Gonzales Mitzi M. , Tarumi Takashi , Villalpando Astrid , Alkatan Mohammed , Pyron Martha , Tanaka Hirofumi , Haley Andreana P.
Published: March 2016

Objectives: Excessive adipose tissue, especially in the abdominal area, is associated with increased risk of dementia in older adults. However, the mechanisms underlying this relationship are poorly understood. As increased adiposity is also associated with lower circulating levels of brain-derived neurotrophic factor (BDNF), a key molecule modulating brain plasticity and neuronal regeneration, we hypothesized that the changes in cognition that occur as a result of excessive abdominal adiposity would be driven by lower levels of circulating BDNF. Methods: Fasting blood samples were obtained from 60 participants aged 40–60 years (mean±SD=52.3±5.6) and BDNF levels were assessed with an enzyme linked immunosorbent assay. Abdominal adiposity was measured using a ratio of waist circumference to hip circumference (WHR). Participants also completed a neuropsychological assessment battery to assess executive function. Statistical mediation was assessed using traditional causal steps and nonparametric bootstrapping. Results: Higher WHR was significantly associated with poorer performance on the Controlled Oral Word Association (COWA) letter fluency test (β=−0.489; p=.003) and lower levels of circulating BDNF (β=−0.345; p=.006). Linear regression and bootstrapping methods indicated that BDNF fully mediated the relationship between WHR and performance on the COWA (β=0.60; 95% confidence interval [−3.79, −0.26]). Conclusions: The relationship between higher WHR and verbal fluency was fully statistically mediated by circulating BDNF levels. The BDNF pathway is thus a useful probable mechanism through which executive function decline occurs in individuals with high abdominal adiposity. BDNF enhancing interventions (physical exercise and dietary restriction) could thus be used to improve executive function in these individuals. (JINS, 2016, 22, 1–8)
Mass Functions & Stellar Populations of Globular Clusters
Authors: Guhathakurta P. , Piotto G. , Vesperini E.
Published: March 2016

I present a summary of results from various HST photometric studies of the dense central regions of Galactic globular clusters that my collaborators and I have carried out over the last 6 years. The dataset includes short exposures of 47 Tuc, M15, M3 and M13 obtained with the aberrated Planetary Camera-I (PC-I) and F555W (“V”) and F785LP (“I”) filters, as well as post-refurbishment Wide Field Planetary Camera 2 (WFPC2) snapshots of the post core collapse clusters M15, M30, and NGC 6624 in F336W (“U”), F439W (“B”), and V. Recently, a very deep, doubly oversampled PC-I U image of the core of 47 Tuc, and accompanying B and V images, have also been analyzed. In addition, we have carried out extensive checks of incompleteness and photometric error with the help of multiband image simulations that mimic the relevant characteristics of the HST PC-I and WFPC2 images: empirical point spread function, crowding effects based on a realistic density profile and stellar luminosity function (LF), noise, undersampling, A/D saturation, etc..
Recent Topics in Spectroscopy of A-Type and Related Stars
Authors: Takeda Yoichi
Published: March 2016

The NLTE abundance analyses concerning late-B through A stars carried out before 1990 have been well summarized by Takada-Hidai (1991), which may be consulted for details; about 10 elements had been studied in NLTE by that time.
Diffusion in CP Stars: The Quest for Accuracy
Authors: Alecian G.
Published: March 2016

We present a brief review about recent progresses concerning the study of diffusion processes in CP stars. The most spectacular of them concerns the calculation of radiative accelerations in stellar envelopes for which an accuracy better than 30% can now be reached for a large number of ions. This improvement is mainly due to huge and accurate atomic and opacity data bases available since the beginning of the 90’s. Developments of efficient computational methods have been carried out to take advantage of these new data. These progresses have, in turn, led to a better understanding of how the element stratification is building up with time. A computation of self-consistent stellar evolution models, including time-dependent diffusion, can now be within the scope of the next few years. However, the progresses previously mentioned do not apply for stellar atmospheres and upper layers of envelopes.
Model for the Transient Emission from Blazars
Authors: Levinson Amir
Published: March 2016

The discovery of strong, variable gamma-ray sources identified with blazars by CGRO has motivated many theoretical investigations concerning the emission from relativistic jets, and several models of gamma-ray blazars have recently been developed (e.g., Dermer & Schlickeiser 1993; Bloom & Marscher 1993; Manneheim 1993; Sikora, et al. 1994; Blandford &; Levinson 1995). However, most of these efforts have been devoted to examine spectral properties of blazars using steady-state models, which are most suitable for exploring quiescent states. Although some progress in identifying the emission mechanisms in different types of blazars, and constraining the content and dynamics of relativistic jets on small scales has been made, it has became widely recognized that quantitative analysis of variability data is crucial for advancing our understanding of the nature of relativistic jets further. Despite recent observational efforts (e.g., Reich et al. 1993; Maraschi et al. 1994; Wagner 1996; Buckley et al. 1996; Takahashi et al. 1996; Mattox et al. 1997) to characterize the transient emission in blazars, only very few attempts have been made (see e.g., Romanova & Lovelace 1997) to model variability data using time dependent models.
Transient Events and Their Solar Magnetic Field
Authors: Vial J.-C.
Published: March 2016

Excellent review papers have been presented in this session by S. Solanki (Manifestations of solar magnetic fields), K. Dere (Coronal Mass Ejections and interplanetary ejecta) and W. Droege (Particle acceleration by waves and fields) and the relevant texts can be found in this volume.

The Joint Discussion benefited from three contributed papers: X-Ray/Radio network flares of the quiet Sun by A.O. Benz, S. Krucker, L.W. Acton, and T.S. Bastian (presented by A.O. Benz) Radio observations of coronal X-ray jets by M.R. Kundu
Cooperation, Collaboration and Language: Science and its Transition
Authors: Hidayat Bambang
Published: March 2016

Before going to the central theme it is perhaps necessary to say what science is, as opposed to other human knowledge. In a rather short statement science may be defined as a world picture, or it may be closer to the heart of the matter if it is said that science is the product of organized fantasy about the real world. Up to this point it must be hastily added that there are also many other branches in human knowledge that share the same characteristics with science. For example, experiment is thought to be peculiar to science. Actually the alchemists of the middle ages did undertake experiments. What was missing in their experiments -and only later applied by Lavoisier and other giants of science in that period- are the hypothetical-deduction methods that science multiplied. Again, observations and logic were also thought to be peculiar to science. We learned, however, the astrologers did make observations and that theologians had logic and that logic is is perhaps the most methodological component of all human inquiry. Thus, as such, one would not be able to discern science from the rest of human activities. But there are boundaries within which science can legitimately operate. The first one is that science denies two types of truth: truth by logic and truth by faith. On the other hand science accommodates only one truth. The other boundary is the constant test by internal logic of necessity and by external public record. These boundary conditions must always be observed, as otherwise one will fall into the realm of magic.
Steps Toward the Moon-Based Astronomy Planning in Japan
Authors: Kaifu N.
Published: March 2016

Lunar surface is, in spite of disadvantages on payload compared with those in the distant orbits, extremely attractive for future astronomical observations with large and complicated observing instruments. The Moon will provide firm and large base, very stable temperature and low background in some selected sites. In addition, the aids of human activities on the Moon can be expected in the near future. We have been discussing the small but realistic steps toward the future Moon-based astronomy, as part of Japanese lunar exploration plans with HI rockets. The fundamental Policy of Japan’s Space Development which was approved by Space Activities Commission in 1996 described that Japan will continuously promote unmanned lunar exploration and study the feasibility of a systematic exploration program for science and possible activities on the Moon, under a phase-by-phase approach. The plan includes a possibility of astronomical observations on the lunar surface.

Some pilot-type astronomical plans, starting from very small-size telescopes in optical/IR and mm-wave etc. are under discussion. We report here on the general background, discussion including proposed plans, and steps toward the future moon-based observatories.
JD23 The Leonid Meteor Storms:- Historical Significance and Upcoming Opportunities
Authors: Williams I.P.
Published: March 2016

Without doubt, the Leonid stream is the most famous of all the known meteoroid streams. The reason for this is not hard to find, the display of meteors that it produces at times far surpassess anything that any other shower can produce. The showers of 1799, 1833 and 1966 all have numerous engravings or photographs recording the splendidness of the displays. The recorded history of the appearances of spectacular Leonid displays dates back for two millenia. Though the associated parent comet, 55/P Tempel-Tuttle, was only discovered in 1861.
Infrared Observations of Galaxy Clusters
Authors: Elbaz D.
Published: March 2016

The evolution of galaxy clusters from their formation due to the merging of sub structures, the bulk of star formation and subsequent chemical enrichment of the intra-cluster medium, is expected to be quite recent (z<l-2) in the hierarchical clustering scenario (White & Frenk 1991).
ISO Observations of Solar-System Objects
Authors: Leinert CH. , Encrenaz TH.
Published: March 2016

The Solar System is characterized by a large variety of objects, with sizes ranging from more than a hundred thousand km down to less than a /mi. All solar-system IR spectra are the sum of two components: at short wavelengths, the reflected sunlight provides information upon the albedo and the chemical composition of the body; at longer wavelengths (typically above 3 to 5 /um), the thermal emission provides information on the temperature of the surface or the atmosphere, and on the vertical distribution of atmospheric constituents.
Serumn-3 polyunsaturated fatty acids are inversely associated with longitudinal changes in depressive symptoms during pregnancy
Authors: Pinto T. J. P. , Vilela A. A. F. , Farias D. R. , Lepsch J. , Cunha G. M. , Vaz J. S. , Factor-Litvak P. , Kac G.
Published: March 2016

Backgrounds.

N-3 polyunsaturated fatty acids (PUFAs) have been hypothesised to be protective for depression during pregnancy. However, there are few data and no consensus regarding this association. In this line, we aim to evaluate if the concentration ofn-3 andn-6 PUFAs, and their ratio, are associated with depressive symptoms throughout pregnancy.

Method.

A prospective cohort of 172 Brazilian women was followed at 5–13th, 20–26th and 30–36th weeks of gestation. The presence of depressive symptoms was evaluated using the Edinburgh Postnatal Depression Scale (EPDS) at each pregnancy trimester. Depression was defined as an EPDS score ≥11. The concentrations ofn-3 [α-linolenic acid; eicosapentaenoic acid (EPA); docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA)] andn-6 PUFAs [linoleic acid; γ linolenic acid; eicosadienoic acid; eicosatrienoic acid; arachidonic acid; docosatetraenoic acid and docosapentaenoic acid] were expressed as absolute (μg/ml) values. The totaln-6/n-3 ratio was calculated. Statistical analyses were performed using univariate and adjusted random intercept logistic model for each fatty acid (FA) considering the longitudinal nature of data. Covariates were selected as potential confounders based on their biological plausibility of having an association with the concentration of FA and depressive symptoms during pregnancy.

Results.

The prevalence of depressive symptoms was high in all pregnancy trimesters (1st = 33.7%; 2nd = 18.9%; 3rd = 17.4%). We did not find differences in means FA concentrations by depressive symptom classification, for each follow-up visit. The women presented a 5% decrease in the odds of having depressive symptoms for each one-week increase in the gestational age. As individual women progressed through pregnancy, higher concentrations of EPA (odds ratio (OR) = 0.92; 95% CI: 0.86–0.99), DHA (OR = 0.96; 95% CI: 0.93–0.99), DPA (OR = 0.87; 95% CI: 0.77–0.99) and totaln-3 (OR = 0.98; 95% CI: 0.96–0.99) were associated with a lower odds of depressive symptoms, while higher totaln-6/n-3 ratio were associated with greater odds of depressive symptoms (OR = 1.40; 95% CI: 1.09–1.79). We detected a decrease in the probability of depressive symptoms as concentrations of totaln-3 FA, α-linolenic acid, DPA, and DHA increased. We also observed a sharper decline for women with initial greater chance of depressive symptoms compared with those with lower chance of having these symptoms.

Conclusions.

We found a high prevalence of depressive symptoms in low-income Brazilian pregnant women and no significant associations betweenn-6 FA and depressive symptoms. Lower serum concentrations of DHA, EPA and DPA and a highern-6/n-3 ratio at each pregnancy trimester were associated with higher odds of depressive symptoms throughout pregnancy.
Introduction: Canon Law and its Practice in Colonial Latin America
Authors: Traslosheros Jorge E.
Published: March 2016

The three papers included here, written by Ana de Zaballa, Pilar Latasa, and Gabriela Ramos, constitute a highly professional effort within the study of canon law in colonial Spanish America. These papers allow us to perceive how closely linked pastoral concerns, legal imagination, and judicial practices were during that period. To fully appreciate the importance of these four investigations, we must first briefly lay out the current state of academic studies in canon law in “las Indias Occidentales,” what today is generally called viceregal or colonial Spanish America.
Validierung der deutschen Kurzversion des Maslach-Burnout-Inventars für Studierende (MBI-SS KV)
Authors: Wörfel Franziska , Gusy Burkhard , Lohman Katrin , Kleiber Dieter
Published: March 2016

Zusammenfassung. Zur Anwendung bei Studierenden wurde das Maslach-Burnout-Inventar für Studierende ins Deutsche übersetzt, sowie gekürzt. Mit Daten von 9.663 Studierenden aus verschiedenen Erhebungen wurde die Faktorstruktur geprüft. Die zu Grunde gelegte dreifaktorielle Struktur konnte empirisch bestätigt werden und die drei Dimensionen erwiesen sich als hinreichend reliabel. Die konvergente Validität wurde mit inhaltsnahen Konstrukten belegt. Explorativ wurden außerdem depressive Studierende mit nicht depressiven Studierenden auf allen drei Dimensionen verglichen, hierbei wurden hypothesenkonform signifikante Unterschiede festgestellt. Die Ergebnisse der Analysen sprechen für die Anwendbarkeit der deutschen Kurzversion des Maslach-Burnout-Inventars (MBI-SS KV), die sich besonders für Mehrthemenbefragungen eignet.
Magnetic phases of spin-1 spin–orbit-coupled Bose gases
Authors: Campbell D. L. , Price R. M. , Putra A. , Valdés-Curiel A. , Trypogeorgos D. , Spielman I. B.
Published: March 2016

Phases of matter are characterized by order parameters describing the type and degree of order in a system. Here we experimentally explore the magnetic phases present in a near-zero temperature spin-1 spin–orbit-coupled atomic Bose gas and the quantum phase transitions between these phases. We observe ferromagnetic and unpolarized phases, which are stabilized by spin–orbit coupling’s explicit locking between spin and motion. These phases are separated by a critical curve containing both first- and second-order transitions joined at a tricritical point. The first-order transition, with observed width as small as h × 4 Hz, gives rise to long-lived metastable states. These measurements are all in agreement with theory.
Tracking ocean heat uptake during the surface warming hiatus
Authors: Liu Wei , Xie Shang-Ping , Lu Jian
Published: March 2016

Ocean heat uptake is observed to penetrate deep into the Atlantic and Southern Oceans during the recent hiatus of global warming. Here we show that the deep heat penetration in these two basins is not unique to the hiatus but is characteristic of anthropogenic warming and merely reflects the depth of the mean meridional overturning circulation in the basin. We find, however, that heat redistribution in the upper 350 m between the Pacific and Indian Oceans is closely tied to the surface warming hiatus. The Indian Ocean shows an anomalous warming below 50 m during hiatus events due to an enhanced heat transport by the Indonesian throughflow in response to the intensified trade winds in the equatorial Pacific. Thus, the Pacific and Indian Oceans are the key regions to track ocean heat uptake during the surface warming hiatus.
A developmentally regulated switch from stem cells to dedifferentiation for limb muscle regeneration in newts
Authors: Tanaka Hibiki Vincent , Ng Nathaniel Chuen Yin , Yang Yu Zhan , Casco-Robles Martin Miguel , Maruo Fumiaki , Tsonis Panagiotis A. , Chiba Chikafumi
Published: March 2016

The newt, a urodele amphibian, is able to repeatedly regenerate its limbs throughout its lifespan, whereas other amphibians deteriorate or lose their ability to regenerate limbs after metamorphosis. It remains to be determined whether such an exceptional ability of the newt is either attributed to a strategy, which controls regeneration in larvae, or on a novel one invented by the newt after metamorphosis. Here we report that the newt switches the cellular mechanism for limb regeneration from a stem/progenitor-based mechanism (larval mode) to a dedifferentiation-based one (adult mode) as it transits beyond metamorphosis. We demonstrate that larval newts use stem/progenitor cells such as satellite cells for new muscle in a regenerated limb, whereas metamorphosed newts recruit muscle fibre cells in the stump for the same purpose. We conclude that the newt has evolved novel strategies to secure its regenerative ability of the limbs after metamorphosis.
Revealing the role of molecular rigidity on the fragility evolution of glass-forming liquids
Authors: Yildirim C. , Raty J.-Y. , Micoulaut M.
Published: March 2016

If quenched fast enough, a liquid is able to avoid crystallization and will remain in a metastable supercooled state down to the glass transition, with an important increase in viscosity upon further cooling. There are important differences in the way liquids relax as they approach the glass transition, rapid or slow variation in dynamic quantities under moderate temperature changes, and a simple means to quantify such variations is provided by the concept of fragility. Here, we report molecular dynamics simulations of a typical network-forming glass, Ge–Se, and find that the relaxation behaviour of the supercooled liquid is strongly correlated to the variation of rigidity with temperature and the spatial distribution of the corresponding topological constraints, which ultimately connect to the fragility minima. This permits extending the fragility concept to aspects of topology/rigidity, and to the degree of homogeneity of the atomic-scale interactions for a variety of structural glasses.
Perversions with a twist
Authors: Silva Pedro E. S. , Trigueiros Joao L. , Trindade Ana C. , Simoes Ricardo , Dias Ricardo G. , Godinho Maria Helena , de Abreu Fernao Vistulo
Published: March 2016

Perversions connecting two helices with symmetric handedness are a common occurrence in nature, for example in tendrils. These defects can be found in our day life decorating ribbon gifts or when plants use tendrils to attach to a support. Perversions arise when clamped elastic filaments coil into a helical shape but have to conserve zero overall twist. We investigate whether other types of perversions exist and if they display different properties. Here we show mathematically and experimentally that a continuous range of different perversions can exist and present different geometries. Experimentally, different perversions were generated using micro electrospun fibres. Our experimental results also confirm that these perversions behave differently upon release and adopt different final configurations. These results also demonstrate that it is possible to control on demand the formation and shape of microfilaments, in particular, of electrospun fibres by using ultraviolet light.
Characterization and expression of AMP-forming Acetyl-CoA Synthetase from Dunaliella tertiolecta and its response to nitrogen starvation stress
Authors: Liang Ming-Hua , Qv Xiao-Ying , Jin Hong-Hao , Jiang Jian-Guo
Published: March 2016

AMP-forming acetyl-CoA synthetase (ACS) catalyzes the formation of acetyl-CoA. Here, a cDNA of ACS from Dunaliella tertiolecta (DtACS) was isolated using RACEs. The full-length DtACS cDNA (GenBank: KT692941) is 2,464 bp with a putative ORF of 2,184 bp, which encodes 727 amino acids with a predicted molecular weight of 79.72 kDa. DtACS has a close relationship with Chlamydomonas reinhardtii and Volvox carteri f. nagariensis. ACSs existing in Bacteria, Archaea and Eukaryota share ten conserved motifs (A1–A10) and three signature motifs (I–III) of the acyl-adenylate/thioester forming enzyme superfamily. DtACS was expressed in E. coli BL21 as Trx-His-tagged fusion protein (~100 kDa) and the enzymatic activity was detected. The recombinant DtACS was purified by HisTrapTM HP affinity chromatography to obtain a specific activity of 52.873 U/mg with a yield of 56.26%, which approached the specific activity of ACS isolated from other eukaryotes. Kinetic analysis indicated that the Km of DtACS was 3.59 mM for potassium acetate and the purified DtACS exhibited a temperature optimum of 37 °C and a pH optimum of 8.0. In addition, the expression levels of DtACS were increased after nitrogen starvation cultivation, indicating that ACS activity may be related to the lipid accumulation under nitrogen deficient condition.
Boosting the power performance of multilayer graphene as lithium-ion battery anode via unconventional doping with in-situ formed Fe nanoparticles
Authors: Raccichini Rinaldo , Varzi Alberto , Chakravadhanula Venkata Sai Kiran , Kübel Christian , Passerini Stefano
Published: March 2016

Graphene is extensively investigated and promoted as a viable replacement for graphite, the state-of-the-art material for lithium-ion battery (LIB) anodes, although no clear evidence is available about improvements in terms of cycling stability, delithiation voltage and volumetric capacity. Here we report the microwave-assisted synthesis of a novel graphene-based material in ionic liquid (i.e., carved multilayer graphene with nested Fe3O4 nanoparticles), together with its extensive characterization via several physical and chemical techniques. When such a composite material is used as LIB anode, the carved paths traced by the Fe3O4 nanoparticles, and the unconverted metallic iron formed in-situ upon the 1st lithiation, result in enhanced rate capability and, especially at high specific currents (i.e., 5 A g−1), remarkable cycling stability (99% of specific capacity retention after 180 cycles), low average delithiation voltage (0.244 V) and a substantially increased volumetric capacity with respect to commercial graphite (58.8 Ah L−1 vs. 9.6 Ah L−1).
NRP2 transcriptionally regulates its downstream effector WDFY1
Authors: Dutta Samikshan , Roy Sohini , Polavaram Navatha S , Baretton Gustavo B. , Muders Michael H. , Batra Surinder , Datta Kaustubh
Published: March 2016

Neuropilins (NRPs) are cell surface glycoproteins that often act as co-receptors for plexins and VEGF family receptors. Neuropilin-2 (NRP2), a family member of NRPs, was shown to regulate autophagy and endocytic trafficking in cancer cells, a function distinctly different from its role as a co-receptor. WD Repeat and FYVE domain containing 1 (WDFY1)–protein acts downstream of NRP2 for this function. Our results indicated that NRP2 maintains an optimum concentration of WDFY1 by negatively regulating its expression. Since increased expression of WDFY1 reduces the endocytic activity, maintenance of WDFY1 level is crucial in metastatic cancer cells to sustain high endocytic activity, essential for promotion of oncogenic activation and cancer cell survival. Here, we have delineated the underlying molecular mechanism of WDFY1 synthesis by NRP2. Our results indicated that NRP2 inhibits WDFY1 transcription by preventing the nuclear localization of a transcription factor, Fetal ALZ50-reactive clone 1 (FAC1). Our finding is novel as transcriptional regulation of a gene by NRP2 axis has not been reported previously. Regulation of WDFY1 transcription by NRP2 axis is a critical event in maintaining metastatic phenotype in cancer cells. Thus, inhibiting NRP2 or hyper-activating WDFY1 can be an effective strategy to induce cell death in metastatic cancer.
Phosphorylated 4EBP1 is associated with tumor progression and poor prognosis in Xp11.2 translocation renal cell carcinoma
Authors: Qu Yuanyuan , Zhao Rui , Wang Hongkai , Chang Kun , Yang Xiaoqun , Zhou Xiaoyan , Dai Bo , Zhu Yao , Shi Guohai , Zhang Hailiang , Ye Dingwei
Published: March 2016

Two main signaling pathways, PI3K-AKT-mTOR and RAS-MAPK, are involved in transmitting the proliferative signals which play critical roles in human cancers. However, the functions of these pathways in Xp11.2 RCC remain undefined. This study aimed to explore the expression of mTOR and MAPK cascades in Xp11.2 RCC and to assess the prognostic significance of proteins evaluated. Immunohistochemistry was performed to evaluate the expression of 4EBP1, p-4EBP1, p-mTOR, p-S6K and p-MAPK in 36 adult Xp11.2 RCC patients who were confirmed by FISH assay. Cox regression models were used to evaluate the prognostic value of all covariates. Among 36 assessed patients, 14 (38.9%), 26 (72.2%), 16 (44.4%), 19 (52.8%), and 9 (25.0%) patients showed high expression of 4EBP1, p-4EBP1, p-mTOR, p-S6K, and p-MAPK, respectively. We noted that p-4EBP1 expression was significantly correlated with lymph node metastases (P = 0.027). Multivariate analysis showed that high p-4EBP1 expression was an independent adverse prognostic factor for both PFS (HR = 33.750, P = 0.017) and OS (HR = 56.111, P = 0.026). Our findings suggest that p-4EBP1 may serve as a funnel factor that converge the upstream proliferative oncogenic signals. Effective inhibition of the pathways responsible for 4E-BP1 phosphorylation might be a useful strategy to improve the outcome of Xp11.2 RCC patients.
Characterization and compression of dissipative-soliton-resonance pulses in fiber lasers
Authors: Li Daojing , Li Lei , Zhou Junyu , Zhao Luming , Tang Dingyuan , Shen Deyuan
Published: March 2016

We report numerical and experimental studies of dissipative-soliton-resonance (DSR) in a fiber laser with a nonlinear optical loop mirror. The DSR pulse presents temporally a flat-top profile and a clamped peak power. Its spectrum has a rectangle profile with characteristic steep edges. It shows a unique behavior as pulse energy increases: The rectangle part of the spectrum is unchanged while the newly emerging spectrum sits on the center part and forms a peak. Experimental observations match well with the numerical results. Moreover, the detailed evolution of the DSR pulse compression is both numerically and experimentally demonstrated for the first time. An experimentally obtained DSR pulse of 63 ps duration is compressed down to 760 fs, with low-intensity pedestals using a grating pair. Before being compressed to its narrowest width, the pulse firstly evolves into a cat-ear profile and the corresponding autocorrelation trace shows a crown shape, which distinguishes itself from properties of other solitons formed in fiber lasers.
Charge carrier coherence and Hall effect in organic semiconductors
Authors: Yi H. T. , Gartstein Y. N. , Podzorov V.
Published: March 2016

Hall effect measurements are important for elucidating the fundamental charge transport mechanisms and intrinsic mobility in organic semiconductors. However, Hall effect studies frequently reveal an unconventional behavior that cannot be readily explained with the simple band-semiconductor Hall effect model. Here, we develop an analytical model of Hall effect in organic field-effect transistors in a regime of coexisting band and hopping carriers. The model, which is supported by the experiments, is based on a partial Hall voltage compensation effect, occurring because hopping carriers respond to the transverse Hall electric field and drift in the direction opposite to the Lorentz force acting on band carriers. We show that this can lead in particular to an underdeveloped Hall effect observed in organic semiconductors with substantial off-diagonal thermal disorder. Our model captures the main features of Hall effect in a variety of organic semiconductors and provides an analytical description of Hall mobility, carrier density and carrier coherence factor.
Retrieving transient conformational molecular structure information from inner-shell photoionization of laser-aligned molecules
Authors: Wang Xu , Le Anh-Thu , Yu Chao , Lucchese R. R. , Lin C. D.
Published: March 2016

We discuss a scheme to retrieve transient conformational molecular structure information using photoelectron angular distributions (PADs) that have averaged over partial alignments of isolated molecules. The photoelectron is pulled out from a localized inner-shell molecular orbital by an X-ray photon. We show that a transient change in the atomic positions from their equilibrium will lead to a sensitive change in the alignment-averaged PADs, which can be measured and used to retrieve the former. Exploiting the experimental convenience of changing the photon polarization direction, we show that it is advantageous to use PADs obtained from multiple photon polarization directions. A simple single-scattering model is proposed and benchmarked to describe the photoionization process and to do the retrieval using a multiple-parameter fitting method.
Electric-field-induced AFE-FE transitions and associated strain/preferred orientation in antiferroelectric PLZST
Authors: Lu Teng , Studer Andrew J. , Noren Lasse , Hu Wanbiao , Yu Dehong , McBride Bethany , Feng Yujun , Withers Ray L. , Chen Hua , Xu Zhuo , Liu Yun
Published: March 2016

Electric-field-induced, antiferroelectric-ferroelectric (AFE-FE) phase transitions are common for AFE materials. To date, the strain and preferred orientation evolution as well as the role of the intermediate FE state during the successive AFE-FE-AFE phase transitions has not been clear. To this end, we have herein studied a typical AFE Pb0.97La0.02(Zr0.56Sn0.33Ti0.11)O3(PLZST) material usingin-situneutron diffraction. It is striking that the AFE-FE phase transition is not fully reversible: in the electric-field-induced FE state, the induced strain exhibits an elliptical distribution, which in turn leads to significant preferred orientation in the final AFE state after withdrawal of the applied electric-field. The ω-dependent neutron diffraction patterns show clear evidence of the induced strain distribution and associated preferred orientation arising from the AFE-FE phase transition. The current work also provides an explanation for several temperature and electric-field dependent dielectric anomalies as well as unrecovered strain change which appear in AFE materials after exposure to sufficiently high electric fields.
Proteomics of thyroid tumours provides new insights into their molecular composition and changes associated with malignancy
Authors: Martínez-Aguilar Juan , Clifton-Bligh Roderick , Molloy Mark P.
Published: March 2016

Around 5% of the general population have palpable thyroid nodules. Although most thyroid tumours are benign, thyroid cancer represents the most common malignancy of the endocrine system, comprising mainly follicular and papillary thyroid carcinomas. Previous studies have shed some light on the molecular pathogenesis of thyroid cancer but there have not been any comprehensive mass spectrometry-based proteomic studies of large scale to reveal protein expression differences between thyroid tumours and the molecular alterations associated with tumour malignancy. We applied data-independent acquisition mass spectrometry which enabled quantitative expression analysis of over 1,600 proteins from 32 specimens to compare normal thyroid tissue with the three most common tumours of the thyroid gland: follicular adenoma, follicular carcinoma and papillary carcinoma. In follicular tumours, we found marked reduction of the tumour suppressor and therapeutic target extracellular protein decorin. We made the novel observation that TGFβ-induced protein ig-h3 (TGFBI) was found frequently overexpressed in follicular carcinoma compared with follicular adenoma. Proteomic pathway analysis showed changes in papillary carcinoma were associated with disruption of cell contacts (loss of E-cadherin), actin cytoskeleton dynamics and loss of differentiation markers, all hallmarks of an invasive phenotype.
Impaired ROS Scavenging System in Human Induced Pluripotent Stem Cells Generated from Patients with MERRF Syndrome
Authors: Chou Shih-Jie , Tseng Wei-Lien , Chen Chien-Tsun , Lai Yu-Fen , Chien Chian-Shiu , Chang Yuh-Lih , Lee Hsin-Chen , Wei Yau-Huei , Chiou Shih-Hwa
Published: March 2016

Myoclonus epilepsy associated with ragged-red fibers (MERRF) is a mitochondrial disorder characterized by myoclonus epilepsy, generalized seizures, ataxia and myopathy. MERRF syndrome is primarily due to an A to G mutation at mtDNA 8344 that disrupts the mitochondrial gene for tRNA(Lys). However, the detailed mechanism by which this tRNA(Lys) mutation causes mitochondrial dysfunction in cardiomyocytes or neurons remains unclear. In this study, we generated human induced pluripotent stem cells (hiPSCs) that carry the A8344G genetic mutation from patients with MERRF syndrome. Compared with mutation-free isogenic hiPSCs, MERRF-specific hiPSCs (MERRF-hiPSCs) exhibited reduced oxygen consumption, elevated reactive oxygen species (ROS) production, reduced growth and fragmented mitochondrial morphology. We sought to investigate the induction ability and mitochondrial function of cardiomyocyte-like cells differentiated from MERRF-hiPSCs. Our data demonstrate that that cardiomyocyte-like cells (MERRF-CMs) or neural progenitor cells (MERRF-NPCs) differentiated from MERRF-iPSCs also exhibited increased ROS levels and altered antioxidant gene expression. Furthermore, MERRF-CMs or -NPCs contained fragmented mitochondria, as evidenced by MitoTracker Red staining and transmission electron microscopy. Taken together, these findings showed that MERRF-hiPSCs and MERRF-CM or –NPC harboring the A8344G genetic mutation displayed contained mitochondria with an abnormal ultrastructure, produced increased ROS levels and expressed upregulated antioxidant genes.
Hydrogenations and electric field induced magnetic behaviors in armchair silicene nanoribbons
Authors: Zhang Dan , Long Mengqiu , Xie Fang , Ouyang Jun , Xu Hui , Gao Yongli
Published: March 2016

Using the first-principles calculations, we investigate the geometric, electronic and magnetic properties of armchair silicene nanoribbons with different edge hydrogenations. Our results show that the interesting magnetic behaviors such as the bipolar magnetic semiconductor can be found. Moreover, the addition of the transverse electric field can modulate the bipolar magnetic semiconductor to half-metal or spin-splitting metal. And the spin-up electrons are localized at one edge, the spin-down holes localized at the opposite edge under the external electric field. These results may present a new avenue for band engineering of silicene nanoribbons and benefit the design of silicon-based nano-spin-devices in nanoelectronics.
Geometry- and Length Scale-Dependent Deformation and Recovery on Micro- and Nanopatterned Shape Memory Polymer Surfaces
Authors: Lee Wei Li , Low Hong Yee
Published: March 2016

Micro- and nanoscale surface textures, when optimally designed, present a unique approach to improve surface functionalities. Coupling surface texture with shape memory polymers may generate reversibly tuneable surface properties. A shape memory polyetherurethane is used to prepare various surface textures including 2 μm- and 200 nm-gratings, 250 nm-pillars and 200 nm-holes. The mechanical deformation via stretching and recovery of the surface texture are investigated as a function of length scales and shapes. Results show the 200 nm-grating exhibiting more deformation than 2 μm-grating. Grating imparts anisotropic and surface area-to-volume effects, causing different degree of deformation between gratings and pillars under the same applied macroscopic strain. Full distribution of stress within the film causes the holes to deform more substantially than the pillars. In the recovery study, unlike a nearly complete recovery for the gratings after 10 transformation cycles, the high contribution of surface energy impedes the recovery of holes and pillars. The surface textures are shown to perform a switchable wetting function. This study provides insights into how geometric features of shape memory surface patterns can be designed to modulate the shape programming and recovery and how the control of reversibly deformable surface textures can be applied to transfer microdroplets.