1,720,965 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Etude des modes gravito-inertiels dans les étoiles en rotation rapide
No full textThis thesis presents a modelization of the oscillations of stars in rapid rotation. Faced with the numerical difficulty inherent to the direct introduction of the rotation in the dynamical equations, we have developed a novel original approach to understand the properties of a fluid in rapid rotation. The method consists in calculating the trajectories of the characteristics of the mixed operator governing the oscillations. The form of the final orbit is then of paramount importance for our problem. In particular, the appearance of attractors for the characteristics leads to singular solutions which completely disorganize the oscillation spectrum, thus making the identification of modes problematic.Cette thèse présente une modélisation des oscillations d’étoiles en rotation rapide. Devant la difficulté numérique inhérente à l’introduction directe de la rotation dans la dynamique, nous avons développé une nouvelle approche originale pour appréhender les propriétés d’un fluide en rotation rapide. La méthode consiste à calculer les trajectoires des caractéristiques de l’opérateur mixte gouvernant les oscillations. La forme de l’orbite finale est alors d’une importance capitale pour notre problème. En particulier, l’apparition d’attracteurs pour les caractéristiques conduit à des solutions singulières qui désorganisent complètement le spectre d’oscillation, rendant par la même l’identification des modes problématique
Radiative hydrodynamics & Application to the study of pulsations-convection interaction
No full textLes Céphéides sont des étoiles pulsantes utilisées pour calculer les distances dans l'univers (notamment dans le Groupe Local). Elle font partie de la bande d’instabilité du diagramme de Hertzsprung-Russell. Le mécanisme κ (où κ désigne l’opacité du milieu), proposé par Eddington en 1917 pour expliquer ces variations périodiques de rayon et luminosité, est encore mal connu dans lecas de Céphéides froides (bord rouge de la bande d’instabilité) présentant une zone convective en surface.Cette thèse consiste à effectuer des simulations 3D de ces étoiles afin d’étudier l’interaction entre leurs pulsations radiales acoustiques et la convection de surface. On se ramène à un cas simple : l’étude de la propagation de modes acoustiques dans une boite cartésienne dont une partie est convective.Nous utilisons le code Heracles développé au CEA par Édouard Audit, que nous avons complété (ajout d’une étape de dissipation, passage à l’ordre 2 en temps pour l’étape de conduction).Pour valider notre code et notre modèle de Céphéide, nous reproduisons les résultats de Gastine & Dintrans (2011b) à 1D (cas purement radiatifs) et 2D (avec convection) : certaines simulations instables au κ-mécanisme (avec une saturation non-linéaire aux temps longs à 1D) redeviennent stables à 2D à cause de l’influence de la convection. La bande d’instabilité théorique du diagramme de Hertzsprung-Russell est donc trop étroite à 2D.L’hypothèse à vérifier était alors que ces Céphéides retrouvent une certaine instabilité et une saturation non-linéaire lors de simulations 3D. En effet, il est connu que les simulations 2D et 3D de convection différent à bas nombre de Prandtl, ce qui est notre cas. Dès lors, nous montrons que les panaches de convection sont en effet moins forts à 3D et ne perturbent pas autant les pulsations. On retrouve ainsi des simulations instables. Le bord rouge de la bande d’instabilité théorique est donc plus proche du bord observé à 3D qu’à 2D.Enfin, nous montrons que les modèles 1D de convection dépendante du temps de Stellingwerf (1982) et de Kuhfuss (1986) donnent des résultats similaires lorsqu’il s’agit de reproduire le profil de flux convectif des simulations 3D, lorsque la simulation présente des mouvements d’ensemble de type κ-mécanisme. Les deux modèles peinent cependant à reproduire les valeurs de ce flux convectif de manière convaincante. Cela justifie l’importance des simulations 3D.Cepheids are pulsating stars used to calculate distances in the universe (more precisely in the Local Group). They are part of the Hertzsprung-Russell diagram’s instability strip. Their periodic variations (of luminosity and radius) are well explained by κ-mechanism, first suggested by Eddington (1917). But cold Cepheids (red edge of the instability strip) have a convective zone near their surface that affects their pulsation properties.Therefore, this PhD. thesis aims at performing 3D simulations of simplified Cepheids to study the interaction between surface convection and radial pulsations. We actually study the propagation of acoustic modes in a cartesian box partially convective.For this, we use Heracles, a hydrodynamical code developed in CEA, France, by Edouard Audit. We had to complete the code with a dissipation step and a second order (in time) conduction step (which was already available as a first order method).To validate the code and the Cepheid model used, we reproduce Gastine & Dintrans (2011b) results in 1D (radiative cases) and 2D (with convection): some setups that are unstable for κ-mecanism (with nonlinear saturation in 1D simulations) are stable in 2D thanks to convection. The theoretical Hertzsprung-Russell diagram’s instability strip is then too narrow in 2D.The hypothesis for this work was that those Cepheids would be unstable again (with saturation) in 3D due to the fact that convection grows weaker when convective plumes are 3D. 2D and 3D simulations are indeed different when Prandtl number is low as it is in our simulations. We show that pulsations are indeed not quenched anymore and that simulations are unstable. Theoretical 3D instability strip is then closer to the observed one than 2D strip was.Finally, we show that the 1D models of time-dependant convection from Stellingwerf (1982) and Kuhfuß (1986) give similar results for the convective flux of 3D convection with κ-mecanism. But none of them is able to give the exact values. That means that 3D simulations are indeed precious
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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