bluuebunny/crossref_metadata_2025_split huggingface dataset:
L’anax précoce au Québec : une libellule migratrice
Authors: Savard Michel 
Published: January 2014

Dans le cadre des travaux du Migratory Dragonfly Partnership, les limites nord des aires de dispersion et de reproduction de l’anax précoce (Anax junius) au Québec ont été mises à jour à partir de la documentation scientifique et des données inédites des participants à l’Initiative pour un atlas des libellules du Québec. Chaque année, dans les basses terres de l’Outaouais et du Saint-Laurent, les premiers adultes immigrant des États-Unis se montrent en mai, exceptionnellement à la fin avril. L’espèce est occasionnellement rapportée dans les contreforts laurentiens et appalachiens de même que dans les régions habitées situées plus au nord du 47e parallèle, sans apparemment dépasser le 50e parallèle le long des côtes de l’estuaire maritime et du golfe du Saint-Laurent. L’émergence de populations estivantes de naïades se produit régulièrement dans la zone tempérée feuillue entre la mi-août et le début octobre tandis que l’émergence de populations hivernantes de naïades s’observe rarement en juin ou au début juillet dans l’extrême sud du Québec. Dans la zone tempérée mixte, des émergences peuvent se produire dans l’enclave bioclimatique du Témiscouata et fort possiblement dans celle du Saguenay–Lac-Saint-Jean. D’après le modèle climatique de Gérardin et McKenney (2001), la limite nord de reproduction de l’anax précoce pourrait atteindre le 49e parallèle, suivant l’isotherme de 15,7 °C pour les 3 mois les plus chauds. Il semble peu probable que l’anax précoce puisse compléter un cycle vital dans la zone boréale, par exemple à l’île d’Anticosti. L’impact des changements climatiques devrait se manifester sur la précocité de l’arrivée printanière des adultes immigrants et sur l’augmentation de la fréquence des émergences de populations hivernantes et estivantes de naïades.
Incidencia de la beca salario: impacto, perfil y rendimiento de los estudiantes
Authors: Berlanga Vanesa , Figuera Pilar , Pons Ernest 
Published: January 2014

La implantación de las becas de estudio, y	especialmente las becas salario adaptadas a la nueva	situación del Espacio Europeo de Educación Superior,	pretenden garantizar el acceso a los estudios universitarios	a los grupos sociales más desfavorecidos	económicamente. Esta investigación realiza un estudio	ex post facto, de carácter descriptivo-comparativo dirigido	a valorar la incidencia de la beca salario. El estudio se ha	realizado con 10.394 estudiantes de nuevo acceso	de la cohorte 2010-11 de la Universidad de Barcelona. Un total de 642 estudiantes accedieron con la	beca salario, con diferencias en función de la rama	de conocimiento, el sexo y la vía de acceso a la	universidad. En relación a sus compañeros, los estudiantes	con beca provienen de familias con niveles ocupaciones y/o	de estudios inferiores, de manera que contribuye a la equidad en el acceso. Los estudiantes con beca se	matriculan y se presentan, en promedio, a un mayor número de	asignaturas con la finalidad de cubrir los requisitos	académicos de renovación de becas, pero los	resultados académicos finales se ven influidos negativamente. Una posible	explicación es la mayor presión académica de este colectivo	en una fase de por sí complicada: la transición a la	universidad.
Population Pharmacokinetic and Pharmacodynamic Methods
Authors: Bulitta Jürgen B , Holford Nicholas H G 
Published: January 2014

Abstract
Pharmacokinetic and pharmacodynamic models are widely used to provide the quantitative basis for understanding the clinical pharmacology of pharmaceuticals. These models are used to describe both the average behavior in the population and differences between individuals. Pharmacokinetic models describe the time course of absorption, distribution, and elimination of a drug and any metabolites. Pharmacodynamic models describe the relationship between drug concentration and biological response. The pharmacokinetic‐pharmacodynamic model often has to account for a delay between the time course of concentrations and the time course of pharmacodynamic effect. Statistical models can describe the predictable and the unpredictable variability between and within subject variability in response. Predictable variability is most commonly understood for drug elimination processes and typically uses subject factors such as weight, renal function, and other medications to account for between subject differences. Unpredictable variability is usually larger than predictable variability. A wide variety of software has been developed for implementing these pharmacological and statistical models; of these, NONMEM (GloboMax LLC, Hanover, MD) is the most widely used. Newer algorithms are actively being developed. Model building and parameter estimation are often computationally intensive. Population models are used by drug developers to create a rationale framework for development, by regulatory health authorities to evaluate clinical trials and enhance product labels and by clinical researchers to understand human biology and disease progression.
Quality of Life
Authors: Fairclough Diane L. , Ganz Patricia A. 
Published: January 2014

AbstractIn the health sciences, assessment of quality of life and other patient‐reported outcomes are now an integral component of patient‐focused research. Health‐related quality of life (HRQoL) is a multidimensional construct that assesses the extent to which one's usual or expected physical, emotional, and social well‐being are impacted by a medical condition or its treatment. HRQoL may be assessed using generic or disease‐specific instruments. These instruments consist of a set of questions, method of administration, instructions for administration, method of scoring and analysis, and interpretation. Validation of these instruments includes assessment of content validity, internal consistency, test–retest reliability, and discriminant and predictive validity. Some of the statistical issues that arise in the analysis of studies with HRQoL assessments are multiple endpoints, missing data (informative dropout), and interpretation (statistical versus clinical significance).
Sample Size Considerations for Morbidity/Mortality Trials
Authors: Shih Joanna H. 
Published: January 2014

Abstract
Sample size and power determination plays a crucial role in the design of morbidity/mortality clinical trials. To ensure that a trial is adequately sized so that the true treatment effect can be detected with a desired power, it is important to evaluate the assumptions used in the sample‐size calculation procedure. Various close‐form sample‐size formulas have been proposed for the analysis of morbidity/mortality trials with survival endpoints. However, most of them are formed based on restrictive assumptions and do not take into consideration factors that may affect the estimate of the treatment effect. These factors include drop‐in, drop‐out, staggered entry, loss to follow‐up, lags in treatment effects, and informative noncompliance. This article reviews the sample‐size calculation methods for testing the treatment effect in two‐arm survival trials. For each method considered, its basic features, underlying assumptions, and limitations are discussed. Presented first are the test statistics and associated methods that yield close‐form sample‐size formulas. Then attention will be focused on methods with aforementioned complexities in sample‐size calculation.
Sample Size Calculation for Comparing Means
Authors: Wang Hansheng , Chow Shein‐Chung 
Published: January 2014

Abstract
In this article, the focus will be on sample size calculation based on a continuous study endpoint for comparing means (i.e., treatment effects) under some study designs. These designs include parallel designs, crossover designs, titration designs, and enrichment designs (2). Among these designs, parallel designs and crossover designs are probably the two mostly commonly used designs.
Sensitivity, Specificity and Receiver Operator Characteristic (
ROC
) Methods
Authors: Kraemer Helena Chmura 
Published: January 2014

Abstract

Three of the most common problems in medical research are as follows: (
1
) evaluating a medical test against a diagnostic criterion in a population, (
2
) choosing the best among available tests, and finally (
3
) developing the best combination of medical tests. In 1979, a
Lancet
editorial commented that
“The assessment of diagnostic methods belongs to the backwoods of clinical research. New treatments are submitted to thorough testing and books are written on the methodology of the controlled therapeutic trial; but no standards have been fixed for the assessment of diagnostic methods.”
Since 1979, some progress has been reflected in the Standards for Reporting of Diagnostic Accuracy (STARD) guidelines, but statistical methods remain much less developed than the methods for the assessment of treatments in randomized clinical trials. As a result, medical tests often enter general clinical use with little or no convincing documentation of their accuracy, which then has major repercussions on patient health and medical costs.
Stability Study Designs
Authors: Daphne Lin Tsae‐Yun , Chen Chi Wan 
Published: January 2014

AbstractA good stability study design is the key to a successful stability program. In this article, stability designs including full, bracketing, and matrixing designs will be exemplified. A full design involves complete testing of all factor combinations at all time points, which can be costly. The pharmaceutical industry would like to apply bracketing or matrixing design so that not every factor combination will be tested at every time point. The statistical aspects of these stability designs will be discussed in relation to the recent Internation Conference on Harmonization (ICH) guidelines. Several commonly used criteria for design comparison will be presented. The statistical and regulatory considerations on the selection of stability design will also be discussed. The stability study should be well designed so the shelf life of the drug product can be estimated with the high degree of accuracy and precision.
Survival Analysis, Overview
Authors: Andersen Per Kragh , Keiding Niels 
Published: January 2014

AbstractSurvival analysis is the generic name for analysis of time‐to‐event data. The distinguishing feature of such data is the presence of right‐censored observations. Thus, for some subjects, instead of observing the real time to the event, only a lower limit for this time, the right‐censoring time, is known. This kind of incomplete data calls for special statistical techniques for the analysis. This article reviews such methods with cross‐references to other articles dealing with special techniques.
Women's Health Initiative Hormone Therapy Trials
Authors: Bassuk Shari S. , Manson JoAnn E. 
Published: January 2014

AbstractThe Women's Health Initiative (WHI) postmenopausal hormone therapy (HT) trials were designed to determine the balance of benefits and risks of HT taken for chronic disease prevention by initially healthy postmenopausal women (age range, 50—79 years; mean age, 63 years). Women with an intact uterus were randomized to estrogen–progestin or placebo for a mean of 5.6 years; women with hysterectomy were randomized to estrogen alone or placebo for a mean of 7.1 years. Compared with their respective placebo‐group counterparts, women in the estrogen–progestin group were significantly more likely to experience an adverse health event, whereas women in the estrogen‐alone group were as likely to do so. Specifically, estrogen–progestin was associated with increased risks of coronary heart disease (CHD), stroke, venous thromboembolism, and breast cancer, as well as reduced risks of hip fracture and colorectal cancer. Estrogen alone was associated with an increased risk of stroke and a reduced risk of hip fracture; it had no effect on CHD risk. The results do not support the use of HT for chronic disease prevention in postmenopausal women as a whole. However, because few WHI participants were within 5 years of menopause, these trials cannot conclusively determine the risk–benefit balance of HT in recently menopausal women. Accumulating data suggest that the timing of HT initiation in relation to age or menopause onset may critically influence the relationship between such therapy and risk of CHD as well as its overall risk–benefit balance, with younger or recently menopausal women experiencing more favorable effects than older women or women further from menopause.
Biased‐Coin Randomization
Authors: Smith Mike D. 
Published: January 2014

AbstractThe biased coin randomisation is introduced as a procedure to minimize study bias whilst maintaining treatment balance throughout the trial. The range of biased coin randomizations are described for 2 and more than 2 treatment groups, and also for equal and unequal randomization. Biased coin randomizations are described which use both fixed and adaptive levels of coin ‘bias’. The well‐known urn model is described as a special representation of the biased coin randomization, and the link is discussed. Finally, the use of the biased coin randomization procedure for balance within covariate strata, and the application to response adaptive randomizations are described.
Block Randomization
Authors: McEntegart Damian 
Published: January 2014

Abstract
Simple unconstrained randomization is the yardstick for randomization techniques in clinical trials as it is completely unpredictable and provides an unambiguous basis for inference from statistical analysis. But simple randomization is rarely used because of the need to protect the trial from imbalance in the overall numbers allocated to treatment and from temporal bias in the allocations. For these reasons the randomization procedure is often restricted by some form of blocking, the most common being random permuted blocks. The methodology, issues and practical considerations relating to the use of blocked randomization are described. Particular attention is paid to the issue of potential selection bias, which may arise from the predictability of tail allocations towards the end of any block of treatment allocations if the past allocations in the block are known or can be guessed. The merits of using unequally sized blocks to avoid selection bias are discussed in detail. Inference following blocked randomization is also discussed. Alternative forms of blocking are described; these include lists generated from the maximal procedure, the use of rows from Hadamard matrices, Zelen's balanced blocks procedure and mixed randomization. Practical considerations relating to the use of blocked randomization are described including software used to generate random blocks. Also covered are considerations relating to the use of electronic systems to automatically perform allocation from a pre‐defined randomization list; the use of such systems is becoming increasingly common with the advent of telephone interactive voice response (IVR) and web based randomization systems.
Clinical Significance
Authors: Kamath Celia C. , Sloan Jeffrey A. , Cappelleri Joseph C. 
Published: January 2014

AbstractThis article defines clinical significance, as opposed to statistical significance, as it relates to health‐related quality of life measures used in clinical trials. It provides a brief history of the concept and addresses the different perspectives from which it is perceived and interpreted. It describes the current methods used to assess clinical significance and provides several examples of the different ways of measuring, validating, and using clinical significance. Recent developments on the concept are discussed. Finally, directions for future research are highlighted.
Cluster Randomization
Authors: Klar Neil , Donner Allan 
Published: January 2014

AbstractThe purpose of this article is to present a systematic and unified treatment of comparative trials that randomize intact social units, or clusters of individuals, to different intervention groups. Such trials have become particularly widespread in the evaluation of nontherapeutic interventions, including lifestyle modification, educational programs, and innovations in the provision of health care. Their increasing popularity over the last two decades has led to an extensive body of methodology and a growing, but somewhat scattered, literature that cuts across several disciplines in the statistical, social, and medical sciences.
Cox Proportional Hazard Model
Authors: Cai Jianwen , Zeng Donglin 
Published: January 2014

AbstractIn this article, we provide an overview on the Cox proportional hazards model. We discuss the partial likelihood approach for parameter estimation and inference. Some practical issues in using the Cox regression model are discussed, including how to handle tied data, incorporate time‐dependent covariates, and fit the Cox regression model in stratified population. The article also reviews some practical ways for assessing proportional hazards assumption; one authentic example is used to illustrate data analysis using the Cox regression model. Finally, we list a few extensions of the Cox regression model.
Identifying the Most Successful Dose (MSD) in Dose‐Finding Studies
Authors: O'Quigley John , Zohar Sarah 
Published: January 2014

Abstract
From a range of candidate doses, the MSD (most successful dose) is the dose at which the overall success rate—the product of the rate of seeing nontoxicities together with the rate of tumor response—is the highest. Among different algorithms designed to achieve this goal, the one closest to optimal (SIM) is the approach described in O'Quigley et al. (2001). This approach has been extended to the cancer setting by Ivanova (2003) and Zohar and O'Quigley (2006).
Coherence in Phase
I
Clinical Trials
Authors: Cheung Ying Kuen (Ken) 
Published: January 2014

Abstract
This article reviews the coherence principles in phase I dose‐finding studies, in which several doses of a new treatment are tested for safety and the maximum dose exhibiting acceptable toxicity level is identified. Because most phase I designs are outcome‐adaptive, dose assignments for future patients depend on the previous observations in the trial. The coherence principles are ethical stipulations to ensure that dose escalation for a new patient will occur only when the most recent patient does not show sign of toxicity, and de‐escalation will occur only when a toxic outcome has just been reported. In this article, we give examples of coherent designs in the literature, and we discuss related concepts such as group coherence and real‐time coherence in more general clinical situations. We also review the application of the coherence concepts to the calibration of a two‐stage design.
Assessing urbanization impacts on catchment transit times
Authors: Soulsby Chris , Birkel Christian , Tetzlaff Doerthe 
Published: January 2014

AbstractStable isotopes have potential for assessing the hydrologic impacts of urbanization, although it is unclear whether established methods of isotope modeling translate to such disturbed environments. We tested two transit time modeling approaches (using a gamma distribution and a two‐parallel linear reservoir (TPLR) model) in a rapidly urbanizing catchment. Isotopic variability in precipitation was damped in streams with attenuation inversely correlated with urban cover. The models captured this reasonably well, although the TPLR better represented the integrated dual response of urban and nonurban areas with reduced uncertainty. Percent urban cover influenced the shape of the catchment transit time distribution. Total urban cover reduced the mean transit time to <10 days compared with ~1 year and ~2–3 years with 63% and 13% urbanization, respectively, while it was at >4 years for nonurban sites.
Changing effect of El Niño on Antarctic iceberg distribution: From canonical El Niño to El Niño Modoki
Authors: Romanov Yury A. , Romanova Nina A. , Romanov Peter 
Published: January 2014

AbstractEarlier studies indicate that during El Niño events the iceberg concentration increases in the east of the Pacific sector and in the west of the Atlantic sector of Southern Ocean, but decreases in the center of the Pacific sector. During La Niña the pattern of the iceberg concentration anomalies in these regions reverses. This iceberg redistribution is explained by anomalous winds and currents around an extensive positive atmospheric pressure anomaly that typically develops in the South‐East Pacific during the warm El Niño‐Southern Oscillation (ENSO) phase. In this study, the results of iceberg observations during two cruises of the r/v “Akademik Fedorov” in Antarctica in January–February 2008 (La Niña) and 2010 (El Niño) have been used to examine the consistency of changes in the iceberg distribution in the Southern Ocean related to El Niño events. The analysis of these observations has shown that in the Pacific Sector of Antarctica changes in the iceberg distribution between 2008 and 2010 followed the scenario outlined above and thus could be associated with the ENSO phase change. Contrary to earlier observations, the iceberg concentration in the Atlantic sector of Antarctica did not increase during 2010 El Niño. The latter is explained by a noncanonical type of 2010 El Niño, El Niño Modoki, and associated atmospheric circulation pattern different from the canonical El Niño. Further analysis has shown that a more frequent occurrence of El Niño Modoki in recent years have resulted in weaker links between El Niño events and the Antarctic iceberg distribution.
Cobalt(II)‐Catalyzed Isocyanide Insertion Reaction with Amines under Ultrasonic Conditions: A Divergent Synthesis of Ureas, Thioureas and Azaheterocycles
Authors: Zhu Tong‐Hao , Xu Xiao‐Ping , Cao Jia‐Jia , Wei Tian‐Qi , Wang Shun‐Yi , Ji Shun‐Jun 
Published: January 2014

AbstractCobalt(II) acetylacetonate‐catalyzed isocyanide insertion reactions with amines utilizing tert‐butyl hydroperoxide (TBHP) as an oxidant under ultrasound conditions have been developed, which lead to the synthesis of ureas, thioureas, as well as 2‐aminobenzimidazoles, 2‐aminobenzothiazoles, and 2‐aminobenzoxazoles under the general reaction conditions in up to 96% yields, respectively. The intermediate amino methylidyneaminiums, initiated by cobalt(II) acetylacetonate‐catalyzed reactions of isocyanides with amines, could be easily trapped by different nucleophiles such as water, sulfur, and intramolecular nucleophilic functional groups. This method provides a simple, general and practical protocol for the divergent synthesis of ureas, thioureas and azaheterocycles.magnified image
A Versatile Metal‐Free Intermolecular Aminochlorination of Alkenes
Authors: Martínez Claudio , Muñiz Kilian 
Published: January 2014

AbstractNew reaction conditions for the rapid and productive intermolecular aminochlorination reaction of alkenes using a combination of chloramine‐T and a Brønstedt acid are described. Upon simple protonation of chloramine‐T, conditions for a mild and selective aminochlorination are obtained. In addition, the reaction can proceed to form either of the two possible regioisomers, depending on whether a stoichiometric amount of such an acid activator or acetic acid is used as solvent. The reaction is operative for all different classes of alkenes. A total of over 50 examples is presented to illustrate this concept.magnified image