1,721,027 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
L’impact d’une exposition fœtale à un substituant potentiel du BPA, le BPAF: Caractérisation des effets d’une exposition in utero à un analogue du BPA, le BPAF, sur le développement des cellules germinales femelles chez l’Homme et la souris
No full textNational audienceLe BPAF (substituant potentiel au BPA) est un bisphénol fluoré, principalement utilisé dans la synthèse des fluoroélastomères. Même si son utilisation est pour le moment, restreinte à certains matériaux utilisés en électronique, robotique et en aéronautique, sa présence dans notre environnement n’est pas négligeable ; il est régulièrement détecté dans l’eau, les poussières domestiques, les sédiments et les boues des stations d’épuration. Peu d’études ont été réalisées pour évaluer la toxicité du BPAF. Mais, son analogie structurale au BPA, sa persistance dans l’environnement et sa faible biodégradation justifient l’importance d’une étude sur la toxicité éventuelle du BPAF sur les cellules germinales femelles, déjà connues pour être extrêmement sensibles au BPA
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
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
[Transcriptional regulation and entry into meiosis]
No full textLa méiose est un processus hautement conservé, central dans la reproduction sexuée, permettant la production de cellules haploïdes à partir des cellules germinales diploïdes. Chez les mammifères l’entrée en méiose est étroitement régulée et dépendante du sexe : elle a lieu au cours de la vie fœtale chez la femelle et pendant la vie post-natale chez le mâle. À l’heure actuelle, l’acide rétinoïque (AR) est considéré comme le principal régulateur de l’entrée en méiose : il induirait l’expression de Stra8 (Stimulated by the retinoic acid gene 8), facteur transcriptionnel clé de la transition mitose/méiose. Dans les testicules fœtaux, CYP26B1, enzyme capable de cataboliser l’AR, inhibe l’expression de Stra8 et l’entrée en méiose. Cependant, il n’existe pas de preuve définitive du rôle de l’AR endogène dans l’initiation de la méiose. Nous avons donc tenté de clarifier l’implication de l’AR dans la régulation de Stra8 en vie fœtale. Pour cela nous avons développé une méthode de surexpression ex vivo des enzymes CYP26B1 et CYP26A1, une autre enzyme avec une activité catalytique de l’AR. Nous montrons que CYP26B1 est suffisant pour inhiber STRA8 dans l’ovaire fœtal, indépendamment de la voie de signalisation de l’AR. Nous proposons ainsi que l’AR agisse dans l’amplification de Stra8 plutôt que dans son induction primaire. Récemment deux autres facteurs ont été caractérisés pour leur rôle clé dans la régulation de la transition mitose/méiose au niveau post-transcriptionnel : MEIOC et son partenaire YTHDC2. Nous avons effectué une analyse des mutants Stra8, Meioc et Ythdc2, qui révèlent de nombreuses similarités. Nous émettons donc l’hypothèse de l’existence d’un continuum entre la régulation transcriptionnelle (par STRA8) et post-transcriptionnelle (par MEIOC/YTHDC2) en début de méiose. En outre, la double-invalidation de Stra8 et Meioc ne prévient pas l’entrée en méiose de quelques rares spermatocytes. Nous suggérons donc l’existence de facteurs additionnels, encore à découvrir, contrôlant la transition mitose/méiose.Enfin, nous montrons qu’au moment de la transition mitose/méiose les spermatocytes I sont trancriptionnellement silencieux. Cette répression transcriptionnelle est en partie régulée par Stra8 mais elle est indépendante des évènements clés de la prophase I : cassures double brin, synapsis des chromosomes homologues, changements de la structure chromatinienne. En exploitant une méthode de synchronisation de la spermatogenèse et en immunoprécipitant les ARN néotranscrits, nous avons alors caractérisé le paysage de la transcription en début de méiose pour la première fois. Nous mettons ainsi en évidence des évènements de stabilisation/déstabilisation des ARN ayant lieu au cours de la prophase I. Ces travaux ont donc mis en lumière le haut degré de complexité caractérisant l’entrée en méiose des cellules germinales. Cette dernière est régulée par plusieurs facteurs, dont certains demeurent encore inconnus, aux niveaux transcriptionnel et post-transcriptionnel.Meiosis is a conserved process, allowing the production of haploid germ cells. In mammals, entry into meiosis is sexually dichotomic, taking place during fetal life in ovaries and during postnatal life in testes. In fetal ovaries, Retinoic Acid (RA) is believed to activate Stra8 (Stimulated by the retinoic acid gene 8), a key factor of mitosis/meiosis transition. In fetal testes, CYP26B1, a RA-metabolising enzyme, prevents Stra8 expression. However, the exact role of endogenous RA remains uncertain.The first objective of my work was to clarify the function of endogenous RA in meiotic initiation. For this purpose, we created a model of artificial RA deficiency by ex vivo electroporation of fetal gonads with plasmids encoding Cyp26b1 or Cyp26a1, two RA-metabolising enzymes. We observed that ectopic CYP26B1 is sufficient to prevent STRA8 appearance in germ cells from fetal ovaries. In contrast, overexpression of CYP26A1 only mildly affects the expression of Stra8 mRNA. We thus conclude that CYP26B1 acts independently of RA signalling pathway on meiotic initiation. We propose a two-step model with first a RA-independent Stra8 induction, followed by its RA-dependent amplification.Recently, MEIOC and YTHDC2 have been caracterised as key post-transcriptional regulators of mitosis/meiosis transition. Here, we compare the phenotypes of Stra8, Meioc and Ythdc2 mutant mice Their high similarity prompt us to hypothesise a continuity between transcriptional and post-transcriptional regulations. In parallel, we show that double invalidation of Stra8 and Meioc does not completely prevent meiotic initiation. Thus, we hypothesise the existence of other unknown mitosis/meiosis regulators.Finally, we characterised a genome wide arrest of transcription taking place during mitosis/meiosis transition. This transcriptional silencing is partly dependent of Stra8 but is independent of other key events of meiotic prophase I: double-strand breaks, homologous chromosome synapsis, axe-loop chromosome structure. We took advantage of a spermatogenesis synchronisation protocol and nascent RNA immunoprecipitation, to characterise the transcriptional landscape of early-meiotic germ cells. This highlighted stabilization and destabilization phemomena taking place during prophase I. As a whole, we show the high complexity level of meiosis initiation, which has to be finely regulated by the orchestration of transcriptional and post-transcriptional events
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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