bluuebunny/crossref_metadata_2025_split huggingface dataset:
A comparison of random walks in dependent random environments
Authors: Scheinhardt Werner R. W. , Kroese Dirk P. 
Published: March 2016

AbstractWe provide exact computations for the drift of random walks in dependent random environments, includingk-dependent and moving average environments. We show how the drift can be characterized and evaluated using Perron–Frobenius theory. Comparing random walks in various dependent environments, we demonstrate that their drifts can exhibit interesting behavior that depends significantly on the dependency structure of the random environment.
Markov-modulated Ornstein–Uhlenbeck processes
Authors: Huang G. , Jansen H. M. , Mandjes M. , Spreij P. , De Turck K. 
Published: March 2016

Abstract
In this paper we consider an Ornstein–Uhlenbeck (OU) process (M(t))t≥0 whose parameters are determined by an external Markov process (X(t))t≥0 on a finite state space {1, . . ., d}; this process is usually referred to as Markov-modulated Ornstein–Uhlenbeck. We use stochastic integration theory to determine explicit expressions for the mean and variance of M(t). Then we establish a system of partial differential equations (PDEs) for the Laplace transform of M(t) and the state X(t) of the background process, jointly for time epochs t = t1, . . ., tK. Then we use this PDE to set up a recursion that yields all moments of M(t) and its stationary counterpart; we also find an expression for the covariance between M(t) and M(t + u). We then establish a functional central limit theorem for M(t) for the situation that certain parameters of the underlying OU processes are scaled, in combination with the modulating Markov process being accelerated; interestingly, specific scalings lead to drastically different limiting processes. We conclude the paper by considering the situation of a single Markov process modulating multiple OU processes.
Joint distribution of a spectrally negative Lévy process and its occupation time, with step option pricing in view
Authors: Guérin Hélène , Renaud Jean-François 
Published: March 2016

Abstract
We study the distribution Ex[exp(-q∫0t1(a,b)(Xs)ds); Xt ∈ dy], where -∞ ≤ a < b < ∞, and where q, t > 0 and x ∈ R for a spectrally negative Lévy process X. More precisely, we identify the Laplace transform with respect to t of this measure in terms of the scale functions of the underlying process. Our results are then used to price step options and the particular case of an exponential spectrally negative Lévy jump-diffusion model is discussed.
Queues with advanced reservations: an infinite-server proxy for the bookings diary
Authors: Maillardet R. J. , Taylor P. G. 
Published: March 2016

Abstract
Queues with advanced reservations are endemic in the real world. In such a queue, the 'arrival' process is an incoming stream of customer 'booking requests', rather than actual customers requiring immediate service. We consider a model with a Poisson booking request process with rate λ. Associated with each request is a pair of independent random variables (Ri, Si) constituting a request for service over a period Si, starting at a time Ri into the future. Our interest is in the probability that a customer will be rejected due to capacity constraints. We present a simulation of a finite-capacity queue in which we record the proportion of rejected customers, and then move to an analysis of a queue with infinitely-many servers. Obviously no customers are rejected in the latter case. However, the event that the arrival of the extra customer will cause the number of customers in the queue to exceed C at some point during its service can be used as a proxy for the event that the customer would have been rejected in a system with finite capacity C. We start by calculating the transient and stationary distributions for some performance measures for the infinite-server queue. By observing that the stationary measure for the bookings diary (that is, the list of customers currently on hand, together with their start times and service times) is the same as the law for the entire sample path of an infinite server queue with a specified nonhomogenous Poisson input process, which we call the bookings queue, we are able to write down expressions for the abovementioned probability that, at some time during a requested service, the number of customers exceeds C. This measure serves as a bound for the probability that an incoming arrival would be refused admission in a system with C servers and, for a well-dimensioned system, it is to be hoped that it is a good approximation. We test the quality of this approximation by comparing our analytical results for the infinite-server case against simulation results for the finite-server case.
Predictors of Hospitalization in Patients With Transient Ischemic Attack or Minor Ischemic Stroke
Authors: Kapral Moira K. , Hall Ruth , Fang Jiming , Austin Peter C. , Silver Frank L. , Casaubon Leanne K. , Gladstone David J. , Stamplecoski Melissa , Tu Jack V. 
Published: March 2016

AbstractBackground:Transient ischemic attack (TIA) and minor stroke are associated with a substantial risk of subsequent stroke; however, there is uncertainty about whether such patients require admission to hospital for their initial management. We used data from a clinical stroke registry to determine the frequency and predictors of hospitalization for TIA or minor stroke across the province of Ontario, Canada.Methods:The Ontario Stroke Registry collects information on a population-based sample of all patients seen in the emergency department with acute stroke or TIA in Ontario. We identified patients with minor ischemic stroke or TIA included in the registry between April 1, 2008, and March 31, 2011, and used multivariable analyses to evaluate predictors of hospitalization.Results:Our study sample included 8540 patients with minor ischemic stroke or TIA, 47.2% of whom were admitted to hospital, with a range of 37.6% to 70.3% across Ontario’s 14 local health integration network regions. Key predictors of admission were preadmission disability, vascular risk factors, presentation with weakness, speech disturbance or prolonged/persistent symptoms, arrival by ambulance, and presentation on a weekend or during periods of emergency department overcrowding.Conclusions:More than one-half of patients with minor stroke or TIA were not admitted to the hospital, and there were wide regional variations in admission patterns. Additional work is needed to provide guidance to health care workers around when to admit such patients and to determine whether discharged patients are receiving appropriate follow-up care.
In Defense of Tasks and TBLT: Nonissues and Real Issues
Authors: Long Michael H. 
Published: March 2016

ABSTRACTThe 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

ABSTRACTBoth 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

ABSTRACTThis 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

ABSTRACTThis 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

ABSTRACTThe 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

ABSTRACTTasks 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

AbstractPurposeThere 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 ProceduresAll 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/ResultsIn 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).ConclusionAmong 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

AbstractObjectives: 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)
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
Steps Toward the Moon-Based Astronomy Planning in Japan
Authors: Kaifu N. 
Published: March 2016

AbstractLunar 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.
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.
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

AbstractPhases 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.