1,720,980 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dynamics of active particles in superfluids and their interaction with quantum vortices
No full textLes superfluides sont des fluides non visqueux dans lesquels la vorticité se concentre sur des filaments ayant une circulation quantifiée. Ces objets, appelés vortex quantiques, possèdent un comportement hydrodynamique. Expérimentalement, la dynamique des superfluides est souvent étudiée en utilisant des particules. Les particules sont aujourd’hui devenues l’outil principal pour visualiser les vortex quantiques. Dans cette thèse, nous étudions numériquement et analytiquement la dynamique des particules actives et de taille finie dans les superfluides. Le superfluide est modélisé avec l’équation Gross–Pitaevskii, tandis que les particules sont implémentées comme des potentiels répulsifs mobiles couplés avec la fonction d’onde macroscopique décrivant le superfluide. Le modèle est utilisé pour étudier l’interaction entre les particules et les tourbillons quantiques à très basse température. Cette première partie vise à donner un contexte théorique aux expériences actuelles dans lesquelles des particules macroscopiques sont utilisées pour échantillonner les vortex superfluides et la turbulence quantique. Plus précisément, nous abordons les problèmes suivants : la capture d’une particule par un vortex quantique, les reconnexions des filaments de vortex et la propagation des ondes Kelvin en présence de particules piégées, ainsi que la dynamique des particules dans la turbulence quantique en déclin. Dans la dernière partie du manuscrit, les effets de température finis sont étudiés dans le modèle Gross–Pitaevskii avec une troncature spectrale. L’objectif est de caractériser la dynamique des impuretés immergées dans un bain thermal et comment leur présence modifie les propriétés statistiques du fluide. En particulier, le mouvement aléatoire des impuretés et la dépendance en température du coefficient de frottement sont étudiés. Enfin, le clustering des impuretés et son effet sur les transitions de phase du condensat sont examinés.Superfluids are inviscid flows in which vorticity is supported on filaments with quantized circulation. Such objects, known as quantum vortices, exhibit a hydrodynamical behavior. Experimentally, the dynamics of superfluids has been studied by using particles, which nowadays have become the main tool for visualizing quantum vortices. In this Thesis, we study numerically and analytically the dynamics of active and finite-size particles in superfluids. The superfluid is modeled with the Gross–Pitaevskii equation, while the particles are implemented as moving repulsive potentials coupled with the macroscopic wave function describing the superfluid. Firstly, the model is used to investigate the interaction between particles and quantum vortices at very low temperatures. This part aims to give a theoretical background to the current experiments in which macroscopic particles are used to sample superfluid vortices and quantum turbulence. Specifically, we address the following problems: the capture of a particle by a quantum vortex, the reconnections of vortex filaments and the propagation of Kelvin waves in presence trapped particles and the dynamics of particles in decaying quantum turbulence. In the last part of the manuscript, finite temperature effects are studied in the Fourier-truncated Gross–Pitaevskii model. The goal is to characterize the dynamics of impurities immersed in a thermal bath and how their presence modifies the statistical properties of the fluid. In particular, the random motion of the impurities and the temperature dependence of the friction coefficient are studied. Finally, the clustering of impurities and its effect on the phase transitions of the condensate are investigated
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Rôle de la turbulence sur l'effet dynamo et l'induction magnétique
No full textThe effect of velocity fluctuations on the threshold of the dynamo effect, the magnetic induction, and also the non-linear behaviors in the saturation regime are analysed through a list of eight articles selected. These subjects are studied by numerical simulations in a three-dimensional periodic domain. Direct numerical simulation (DNS) and simulation using sub-grid scale modeling methods (LES), helped to highlight the effect of fluctuations on the threshold and many modes of dynamo in flows sustained with different forcings (Taylor-Green, ABC and G.O. Robert). In these systems in the saturation regime, non-linear effects appear, such as sub-critical bifurcations associated with hysteresis loops, and turbulent intermittent On-Off behaviors. A discussion and perspectives on these topics are presented, together with a long annexe describing the numerical methods and diagnostics that were used in this work.L'effet des fluctuations de vitesse sur le seuil de la dynamo, de l'induction magnétique, et ainsi que des effets non linéaires présents dans le régime de saturation sont étudiés avec une sélection de huit articles. Ces thèmes ont été abordés à travers des simulations numériques dans un domaine périodique tri-dimensionnel. Des simulations numériques directes (DNS) et des méthodes de modélisation sous maille (LES) de la turbulence, ont permis de mettre en évidence l'effet des fluctuation sur le seuil et de nombreux modes de dynamo engendrés dans des écoulements entretenus par différents forçages (Taylor-Green, ABC et G.O. Robert). Dans ces systèmes MHD pendant la phase de saturation, des effets non-linéaires apparaissent, comme des bifurcations sous critiques associées à des cycles d'hystérésis, ainsi qu'un comportement de turbulence intermittente On-Off. Une discussion et des perspectives sur ces thèmes sont présentées, ainsi qu'une annexe sur les méthodes numériques et les diagnostiques ayant été utilisés dans ces travaux
Rôle de la turbulence sur l'effet dynamo et l'induction magnétique
Get PDFThe effect of velocity fluctuations on the threshold of the dynamo effect, the magnetic induction, and also the non-linear behaviors in the saturation regime are analysed through a list of eight articles selected. These subjects are studied by numerical simulations in a three-dimensional periodic domain. Direct numerical simulation (DNS) and simulation using sub-grid scale modeling methods (LES), helped to highlight the effect of fluctuations on the threshold and many modes of dynamo in flows sustained with different forcings (Taylor-Green, ABC and G.O. Robert). In these systems in the saturation regime, non-linear effects appear, such as sub-critical bifurcations associated with hysteresis loops, and turbulent intermittent On-Off behaviors. A discussion and perspectives on these topics are presented, together with a long annexe describing the numerical methods and diagnostics that were used in this work.L'effet des fluctuations de vitesse sur le seuil de la dynamo, de l'induction magnétique, et ainsi que des effets non linéaires présents dans le régime de saturation sont étudiés avec une sélection de huit articles. Ces thèmes ont été abordés à travers des simulations numériques dans un domaine périodique tri-dimensionnel. Des simulations numériques directes (DNS) et des méthodes de modélisation sous maille (LES) de la turbulence, ont permis de mettre en évidence l'effet des fluctuation sur le seuil et de nombreux modes de dynamo engendrés dans des écoulements entretenus par différents forçages (Taylor-Green, ABC et G.O. Robert). Dans ces systèmes MHD pendant la phase de saturation, des effets non-linéaires apparaissent, comme des bifurcations sous critiques associées à des cycles d'hystérésis, ainsi qu'un comportement de turbulence intermittente On-Off. Une discussion et des perspectives sur ces thèmes sont présentées, ainsi qu'une annexe sur les méthodes numériques et les diagnostiques ayant été utilisés dans ces travaux
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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