1,720,981 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
Facing pollution : Impact of urbanisation on trace metal responses in a social insect. The case of the ant Temnothorax nylanderi
No full textL'urbanisation croissante expose les écosystèmes à divers contaminants chimiques, mais ses effets sur les espèces sociales telles que les fourmis restent encore trop peu étudiés malgré leur rôle écologique. Les espèces eusociales pourraient en effet réagir différemment aux polluants en raison de leur mode de vie en groupe. Des travaux antérieurs ont montré que les colonies urbaines de la fourmi Temnothorax nylanderi étaient moins négativement impactées par le cadmium que les colonies forestières. Cette thèse vise à élucider les mécanismes responsables de cette tolérance accrue observée chez les colonies urbaines. Dans une première partie, nous avons mis en évidence que les colonies urbaines de T. nylanderi, bien que vivant dans un environnement plus pollué, ne contenaient pas plus de cadmium, de cuivre et de zinc que les colonies forestières, mais plus de plomb, de façon inversement proportionnelle au nombre d'ouvrières de la colonie. Dans une seconde partie, nous avons montré que lorsqu'elles recevaient de la nourriture polluée au cadmium, les colonies urbaines régulaient mieux leur concentration interne en cadmium, atteignant un plateau de contamination plus faible que les colonies forestières, bien que les capacités de détoxification soient similaires. Enfin, dans une troisième partie, nous avons trouvé que ni les colonies urbaines ni les forestières n'étaient capables de détecter et d'éviter la nourriture contaminée au cadmium, quelle que soit la concentration dans la nourriture, mais que les colonies forestières fourrageaient plus activement que les colonies urbaines. Cette thèse contribue à une meilleure compréhension des mécanismes de réponse des espèces eusociales aux polluants urbains, et souligne l'importance de prendre en compte les traits propres à chaque espèce pour l'utilisation en bioindication et la gestion des impacts de l'urbanisation.Increasing urbanisation exposes ecosystems to a variety of chemical contaminants, yet its effects on social species like ants remain understudied despite their ecological importance. Eusocial species may exhibit unique responses to pollutants due to their social lifestyle. Previous study have shown that urban colonies of the ant Temnothorax nylanderi were less negatively impacted by cadmium than forest colonies. This thesis seeks to elucidate the mechanisms underlying this increased tolerance observed in urban colonies. In the first section, we highlighted that urban colonies of T. nylanderi, despite living in a more contaminated environment, did not contain more cadmium, copper, and zinc than forest colonies, but more lead, inversely proportional to the number of workers in the colony. In the second chapter, we showed that when fed cadmium-contaminated food, urban colonies better regulated their internal cadmium concentration, reaching a lower contamination plateau than forest colonies, although detoxification capacities were similar. Finally, in the third chapter, we found that neither urban nor forest colonies were able to detect and avoid cadmium-contaminated food, regardless of the concentration in the food, but that forest colonies foraged more actively than urban ones. This thesis contributes to a better understanding of the mechanisms by which eusocial species respond to urban pollutants, and highlights the importance of taking into account species-specific traits for use in bioindication and management of the ecological impacts of urbanisation
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
Origins and evolutive potential of intercastes the ant Mystrium rogeri
No full textLes colonies de fourmis produisent occasionnellement des individus intermédiaires entre les reines et les ouvrières (c.-À-D. intercastes). Les intercastes pourraient être impliquées dans l'évolution de nouvelles castes par un processus de réorganisation des phénotypes ancestraux. Afin d'évaluer cette hypothèse, nous avons étudié la validité de trois corollaires de ce modèle évolutif chez la fourmi Mystrium rogeri: (i) les intercastes résultent de la réorganisation de caractères de reines et d'ouvrières; (ii) les intercastes sont susceptibles d'être fonctionnelles parce qu'elles recombinent des comportements qui ont déjà été testé par la sélection chez les reines et les ouvrières; (iii) certains phénotypes intercastes ressemblent à ceux des nouvelles castes ayant évolué de cette façon.Les résultats suggèrent que les intercastes sont générées par des niveaux intermédiaires de facteurs environnementaux induisant des réponses différentielles entre les modules. Les intercastes effectuent les mêmes tâches que les reines et les ouvrières et elles ne sont pas associées à des comportements aberrants. Elles sont plus impliquées que les reines et les ouvrières dans les interactions agonistes et peuvent ainsi entraîner des coûts à l'échelle de la colonie. Les intercastes peuvent attirer les mâles, s'accoupler et pondre des ¿ufs, présentant ainsi un fort potentiel reproducteur. Des changements de pressions de sélection sur les stratégies de reproduction sont alors susceptibles d'entrainer la fixation d'un phénotype intercaste par accommodation génétique. Nos résultats soutiennent l'hypothèse selon laquelle les intercastes peuvent être à l'origine de l'évolution des nouvelles castes.Ant colonies occasionally produce individuals called intercastes. These are morphologically highly variable, but always intermediate between queens and workers. Because of their rarity, intercastes have been little studied. However, they may be involved in the evolution of novel castes through the reorganization of ancestral phenotypes (i.e. developmental recombination). In order to evaluate this hypothesis, we investigated the validity of three corollaries of this evolutionary model in the ant Mystrium rogeri: (i) intercastes must be produce by the reorganization of queen and workers characters following new genetic or environmental input; (ii) they are likely to be functional because they recombine behaviors that have already been tested by selection in queens and workers, unlike a random mutational process that mainly produces deleterious variants; (iii) some intercaste phenotypes may resemble those of new castes suspected to have evolved by this way. In agreement with the phenotypic reorganization hypothesis, our morphometric analyses suggest that intercastes are generated by intermediate levels of environmental factors inducing differential responses among modules. Behavioral records showed that intercastes perform the same tasks than queens and workers and therefore they are not associated with aberrant and costly behaviors. Nevertheless, they are more involved in agonistic interactions than queens and workers and thus may cause significant costs at the colonial level. Behavioral tests showed that some intercastes may attract males, mate, and lay diploid eggs, thereby demonstrating their high reproductive potential. Consequently, new selective pressures on the reproductive strategy may result in the selection of these intercastes and then the fixation of a new canalized phenotype by genetic accommodation of change. This process may explain the multiple evolutions of new reproductive castes (e.g. ergatoid queens). Overall, results presented in this work support the hypothesis that intercastes may be at the origin of the evolution of novel castes by developmental recombination
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
Worker size diversity within ant colonies : group or individual interests?
No full textChez les insectes sociaux, la diversité de taille des individus dans les colonies est supposée améliorer la division du travail et ainsi augmenter la fitness des colonies. Cela fait relativement consensus chez les espèces à forte diversité de taille continue ou bien avec la présence de plusieurs castes non reproductrices. En revanche, chez les espèces à diversité plus limitée, représentant la grande majorité des insectes sociaux, les résultats sont plus contrastés. Cette thèse s’est donc focalisée sur l’intérêt de la taille des ouvrières au sein des colonies de fourmis à diversité modérée. Nous avons dans un premier temps démontré que la taille moyenne et la diversité de taille des ouvrières ne sont pas forcément adaptatives chez notre espèce d’étude, Temnothorax nylanderi, à travers des manipulations expérimentales en milieu semi-naturel durant la période de croissance et durant l’hibernation. Face à ce manque d’intérêts de la taille des individus pour la colonie, nous avons investigué les potentiels intérêts pour les individus. En utilisant la fourmi Mystrium rogeri, nous avons manipulé la prise alimentaire des larves et ainsi étudié le développement des larves sans contraintes de la part des ouvrières. Ces données sur le développement larvaire suggèrent le développement de phénotypes plus grands en l’absence de coercion des larves par les ouvrières. Cela sous-entend à la fois que l’environnement social contrôle fortement la taille des individus produits, mais également qu’une perturbation de cet environnement social et/ou des comportements égoïstes des larves peuvent générer de la diversité de taille dans les colonies de fourmis. Dans un dernier chapitre, nous avons quantifié la contribution de cet environnement social dans la résistance à un perturbateur externe, en utilisant un élément trace. L’idée était de découpler la part sociale représentée par les ouvrières de la part intrinsèque des larves dans la résistance au cadmium en utilisant des colonies de la fourmi Temnothorax nylanderi provenant de villes et de forêts. De manière surprenante, notre étude n’a pas montré de réponses différentielles au cadmium entre ces deux populations concernant les ouvrières et nous n’avons pu tester notre hypothèse initiale que sur les mâles. En revanche, cette dernière étude met en lumière les limites à la résilience des sociétés d’insectes, qui pourraient être sujettes à davantage de stress et de manière plus chronique par rapport aux individus solitaires. Plus globalement, cette thèse ouvre la voie à reconsidérer le rôle de la taille chez les insectes sociaux et la place que prennent les intérêts individuels dans sa détermination. L’amélioration en profondeur des connaissances sur les déterminismes générant la diversité de taille, notamment via la génétique et génomique, aidera à la distinction entre intérêts du groupe et/ou des individus et ainsi à déterminer plus finement le rôle de la taille chez les insectes sociaux.In social insects, size diversity of individuals in colonies is supposed to improve the division of labour and thus increase the fitness of colonies. This is relatively clear in species with high size diversity, either with a continuous range or with the presence of several non-reproductive castes. On the other hand, in species with more limited diversity, representing the vast majority of social insects, the results are more contrasted. This thesis therefore focused on the interest of worker within colonies of ants with moderate diversity. We first demonstrated that the mean size and size diversity of workers are not necessarily adaptive in our study species, Temnothorax nylanderi, through experimental manipulations in a semi-natural environment during the growing season and during overwintering. Faced with this lack of interest in the size of individuals for colony, we investigated the potential interest for individuals. Using the ant Mystrium rogeri, we manipulated the food intake of larvae and thus studied the development of larvae without worker constraints. These data on larval development suggest the development of larvae in larger phenotypes in the absence of worker coercion. This implies both that the social environment strongly controls the size of produced individuals, but also that disturbance of this social environment and/or selfish behaviour of larvae can generate size diversity in ant colonies. In a final chapter, we quantified the contribution of this social environment in resistance to an external disturbance, using a trace element. The idea was to disentangle the social part represented by workers from the intrinsic factors of larvae in cadmium resistance using colonies of the ant Temnothorax nylanderi from cities and forests. Surprisingly, our study did not show differential cadmium responses between these two populations for workers and we were only able to test our initial hypothesis on males. On the other hand, this latest study highlights the limits to the resilience of insect societies, which may be subject to more stress and more frequently compared to solitary individuals. More generally, this thesis paves the way to reconsider the role of size in social insects and the place of individual interests in its determination. The in-depth improvement of knowledge on the determinisms that generate size diversity, notably via genetics and genomics, will help to distinguish between group and/or individual interests and thus to determine more precisely the role of size in social insects
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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