1,721,045 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
A movement model to predict resource discovery by central place foragers : an application to bumblebees
No full textComprendre comment les pollinisateurs se déplacent dans l'espace est essentiel pour comprendre les dynamiques de pollinisation entre les plantes. Il est généralement supposé que les insectes pollinisateurs recherchent les fleurs en suivant des règles de déplacement simples, de sorte que la probabilité de découvrir une fleur dépend essentiellement de sa distance par rapport au nid. Cependant, des travaux expérimentaux montrent que ce n'est pas toujours le cas. Jusqu'à présent, personne n'a proposé de modèle réaliste de déplacement d'insecte pollinisateur qui tienne compte du fait qu'ils sont des "central place foragers" pour prendre en compte le fait que toutes leurs trajectoires commencent et se terminent en un point central : le nid. Afin d'approfondir nos connaissances sur le mouvement exploratoire de ces insectes en tant que "central place foragers", je propose un modèle qui produit des trajectoires d'insecte pollinisateur réalistes en tenant compte de l'autocorrélation de la vitesse angulaire de l'individu, de l'attraction vers le nid et d'un bruit gaussien. Les quatre paramètres de ce modèle ont été ajustés sur la base de trajectoires expérimentales recueillies sur des bourdons (Bombus terrestris) sur le terrain. Le modèle peut décrire non seulement les statistiques de trajectoires des insectes pollinisateurs, mais aussi ceux d'autres animaux qui fourragent autour d'un point central. Le modèle proposé permet de calculer des prédictions théoriques sur la pollinisation en milieu naturel. Dans le présent travail, j'ai exploré les statistiques de découverte des fleurs en fonction de la taille et de la densité des parcelles de fleurs. Les simulations de trajectoires de bourdons mettent en évidence deux effets qui avaient été négligés jusqu'ici : un effet de masquage qui réduit la détection des fleurs proches les unes des autres et un effet d'échelle qui module ce premier effet en fonction de la distance entre les fleurs. Au niveau de la plante, les fleurs éloignées du nid sont plus souvent découvertes par les bourdons dans les environnements à faible densité. Au niveau de la colonie, les butineuses trouvent plus de fleurs lorsque celles-ci sont petites et à des densités moyennes. Ces résultats suggèrent que la pollinisation serait optimisée dans une gamme de densités de fleurs intermédiaires : lorsque la densité est trop faible, trop peu de fleurs sont découvertes ; lorsque la densité devient trop élevée, les fleurs éloignées du nid sont masquées par les fleurs plus proches en raison de l'effet de masquage. Ces résultats indiquent que les processus de recherche et de découverte des ressources sont potentiellement plus complexes que les prédictions fondées sur les seuls effets de distance, et mettent en question l'importance de la distribution et de l'abondance des ressources sur le succès du butinage des insectes pollinisateurs et la pollinisation des plantes.Understanding how pollinators move across space is key to understanding plant mating patterns. Bees are usually assumed to search for flowers randomly or using simple movement rules so that the probability of discovering a flower depends primarily on its distance to the nest. However, experimental work shows this is not always the case. Until now, no one has successfully enunciated a realistic model of bee movement that considers the fact that they are Central Place Foragers and thus they start and end all their movements in the same place: the nest. To further our knowledge of the exploratory movement of central place foraging bees, I propose a model of central place foraging that produces realistic bee trajectories by accounting for the autocorrelation of the bee's angular speed, the attraction to the nest (homing), and Gaussian noise. The four parameters of this model have been tuned based on experimental trajectories collected on bumblebees (Bombus terrestris) in the field. The model not only has the potential to describe the movement patterns of bees but also those of other central place forager animals. The proposed model paves the way to compute theoretical predictions about pollination in the field. Here, I explored the statistics of flower discovery, depending on flower patch sizes and densities. Simulations of bumblebee trajectories highlight two effects that were previously overlooked: a extit{masking effect} that reduces the detection of flowers close to another and a extit{scale effect} that modulates this first effect as a function of the distance between flowers. At the plant level, flowers distant from the nest were more often discovered by bees in low-density environments. At the colony level, foragers found the most flowers when they were small and at medium densities. These results suggest that pollination would be optimized in a range of intermediate flower densities: when the density is too low, few flowers are discovered; when the density is too high, flowers distant from the nest become masked by closer ones (due to the masking effect). These results indicate that the processes of search and discovery of resources are potentially more complex than usually assumed, and question the importance of resource distribution and abundance on bee foraging success and plant pollination
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
Developing spinal cord : from observable collective dynamics to a behavioral model at cell scale
No full textNous proposons un modèle de l'embryogenèse de la moelle épinière considérée comme un système dynamique constitué d'unités comportementales (les cellules). Pour que cet organe soit fonctionnel, il faut que les neurones des différents types soient mis en place au cours de l'embryogenèse, avec le bon nombre de neurones du bon type au bon endroit. Cette mise en place résulte d'un processus dynamique au cours duquel les progéniteurs neuronaux prolifèrent dans les proportions adéquates avant de se différencier en neurones spécialisés. Les données expérimentales disponibles donnent l'évolution des populations de progéniteurs et de neurones, et la balance globale entre prolifération et différenciation. Un premier modèle est énoncé à l'échelle collective pour rendre compte de la dynamique observée sur toute la durée du processus, avec une évolution de la balance prolifération / différenciation ajustée sur les données expérimentales. Un second modèle introduit une différenciation comportementale des progéniteurs sous la forme d'une perte de leur capacité proliférative. Ce changement comportemental, de type tout-ou-rien à l'échelle cellulaire, se traduit à l'échelle collective par une transition continue de la balance prolifération / différenciation telle qu'observée expérimentalement. Enfin, nous explorons un raffinement de ce modèle où ce changement comportemental est gouverné par l'état du système (rétro-contrôle). Nous examinons les différentes possibilités de rétro-contrôles et nous retenons celle qui rend le mieux compte de la dynamique collective observée. En perspective, nous proposons des pistes pour intégrer la dimension spatiale du phénomène, et pour la prolongation de ce travail vers la modélisation du développement du cortex cérébral.We consider the developing spinal cord as a dynamical system made of behavioral units (cells). For the adult spinal cord to be functional, different neurons must be of the right kind at the right place. They are issued from a dynamical process of proliferative and differenciating neural progenitors, with a fine control of the balance between proliferation and differentiation. Some experimental data are available for the evolution of progenitors and neurons population and for how the balance progresses with time. Based on these data, we propose a first model at the collective scale to account for these dynamics all along the process. A second model is proposed at the cell scale which includes a loss of proliferative capacity that progressively concerns more and more progenitors. This behavioural switch at cell scale is reflected by a continous progression of the balance proliferation / differentiation at population scale, as it is experimentally observed. Finally, we introduce a feedback control process so that this progression is under the control of the progenitors and neurons populations. Among the multiple possibilities for this feedback, we point out to the most relevant process. We discuss these findings, and how they can be extended to spatialized dynamics and neocortex development
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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