1,721,005 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
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
Synthesis and study of a series of 2'- or 3'-fluorinated nucleosides analogues
No full textDans le premier chapitre de cette thèse, nous nous sommes intéressés aux virus de l'immunodéficience humaine et des hépatites B et C ainsi qu'aux thérapies utilisées dans le traitement de ces affections. Nous avons introduit l'importance des nucléosides fluorés, et nous avons donné quelques exemples de nucléosides fluorés utilisés en chimiothérapie antivirale et antitumorale. Dans le second chapitre, nous avons présenté une synthèse rapide de 2',3'-didésoxy-3'-fluoro-beta-D-thréo-nucléosides portant les bases pyrimidiques naturelles et substituées en position N3 par un groupement nitro ou amino. Les composés obtenus ont été évaluées contre divers virus à ADN et ARN (y compris le VIH) dans des expériences de culture cellulaire. Dans le troisième chapitre, nous nous somme intéressés à la synthèse de différents 2',3'-didésoxy-2'-fluoro-3'-(N-hydroxyimino), (N-methoxyimino) and (hydroxyl-amino) nucléosides en série pyrimidine. Les composés obtenus ont été évaluées contre divers virus à ADN et ARN dans des expériences de culture cellulaire.In the first chapter, we presented the human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV), as well as the therapies used to treat these diseases. In a second part, we discussed about the importance of the incorporation of fluorine atom into nucleoside analogues, and in a third part of this chapter, we presented the recent literature sources of the synthesis and biological activity of fluorinated nucleosides. In the second chapter, we designed and synthesized a series of 2',3'-dideoxy-3'-fluoro-threo-pyrimidine nucleosides by direct and rapid methodology and evaluated them for their inhibitory effects on a number of RNA and DNA viruses in cell culture experiments. None of these nucleoside derivatives showed any antiretroviral activity nor cytotoxicity. In the third chapter of this manuscript, we synthesized a new series of 2',3'-dideoxy-2'-fluoro-3'-(N-hydroxyimino),(N-methoxyimino) and (hydroxylamino)pyrim idine nucleosides and also evaluated for their inhibitory effects on a number of RNA and DNA viruses, without finding any activity or cytotoxicity
Design, synthesis and study of ecto-5’-nucleotidase inhibitors for cancer chemotherapy
No full textLe projet de thèse est consacré à la conception, la synthèse et l’étude de nouveaux inhibiteurs ciblant des enzymes telles que les 5'-nucléotidases impliquées dans la résistance aux traitements anticancéreux. Les enzymes de cette famille chez l'homme, sont associées à la régulation de pools endogènes de nucléosides et de nucléotides et représentent une cible thérapeutique pertinente pour la chimiothérapie anticancéreuse. La 5’-éctonucléotidase CD73 est une métallophosphatase homodimérique impliquée dans le catabolisme extracellulaire de l’adénosine monophosphate (AMP) en adénosine dans les tissus humains. L’activité de la CD73 a été corrélée au blocage de la réponse immunitaire en raison de la production d’adénosine par cette enzyme, et protège ainsi les cellules cancéreuses de l'immunosurveillance. Par ailleurs, il a été montré que la croissance tumorale, l'invasion des cellules cancéreuses et les métastases sont induites par une surexpression de CD73 dans nombreux types de cancer (sein, vessie, prostate, colorectal et gastrique). Sur la base de résultats préliminaires obtenus dans l’équipe, le projet est dédié au développement et à l'optimisation structurale de nouveaux inhibiteurs. Dans un premier temps, un analogue de la clofarabine a été développé en tant qu’inhibiteur compétitif de cette enzyme. Puis dans un second temps, la synthèse de plusieurs inhibiteurs allostériques à scaffold triazole et thiopyridine a été accomplie afin d’évaluer l’activité de ces dérivés vis-à-vis de la CD73 recombinante et des cellules MDA-MB-231. La modélisation, la dynamique moléculaire et le criblage virtuel ont été utilisés pour l’élaboration de ces nouveaux inhibiteurs. La synthèse chimique a été réalisée au sein de l’équipe Nucléosides & Effecteurs Phosphorylés. La détermination du mécanisme d'inhibition par cinétique enzymatique, et l'évaluation biologique sur des modèles animaux et des lignées cellulaires cancéreuses ont été effectuées en partenariat avec différentes équipes impliquées dans le projet (Dr L. Chaloin, IRIM, UMR 9004, Montpellier; Dr L.P. Jordheim, Pr. C. Dumontet, CRCL, Inserm U1052/CNRS UMR5286, Lyon). Ces travaux de thèse reposent sur la conception, la synthèse et l’étude de nouveaux inhibiteurs de CD73.The thesis project is dedicated to the design, the synthesis and the study of novel inhibitors targeting enzymes such as 5'-nucleotidases involved in resistance to cancer treatments based on the use of cytotoxic nucleoside analogues. Indeed, these enzymes are associated with the regulation of endogenous pools of nucleosides and nucleotides and represent a relevant therapeutic target in anticancer chemotherapy. Ecto-5’-nucleotidase CD73 is an homodimeric metallophosphatase involved in the extracellular catabolism of adenosine monophosphate (AMP) into adenosine in human blood and tissues. The activity of CD73 has been correlated with blocking of the immune response due to the production of adenosine by this enzyme that causes a suppression of the immune response and thus protects cancer cells from immune monitoring. Furthermore, it was shown that the tumor growth, cancer cell invasion and metastasis are mediated by an overexpression of CD73 in many types of cancer (breast, bladder, prostate, colorectal and gastric). On the basis of preliminary results obtained in the team, the project is dedicated to the development and structural optimization of new inhibitors. Firstly, the synthesis of a clofarabine analogue has been developed as a competitive inhibitor of this enzyme. Then, the synthesis of several allosteric inhibitors bearing a triazole or a thiopyridine scaffold has been achieved in order to investigate their activity against the recombined CD73 and MDA-MB-231 cancer cells. Modelling, molecular dynamics and virtual screening has been used for the development of novel structures. The chemical synthesis was carried out within the team Nucleosides & Phosphorylated Effectors. The determination of the inhibition mechanism by enzymatic kinetics, and the biological evaluation on cancer cell lines, and possibly animal models, has been carried out in partnership with various teams already involved in the project (Dr L. Chaloin, IRIM, UMR 9004, Montpellier, Dr LP Jordheim, Pr C. Dumontet, CLRC, Inserm U1052 / CNRS UMR5286, Lyon)
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
Analogues of antitumoral nucleosides. Activation of derivatives of L-deoxythymidine by delivery of functional mutants of deoxycytidine kinase
No full textLes analogues nucléosidiques ont prouvé leur efficacité thérapeutique et sont désormais couramment utilisés en chimiothérapies antivirale et anticancéreuse. Depuis, il a récemment été démontré que les analogues de configuration non naturelle L pouvaient présenter des activités biologiques remarquables au même titre que ceux de configuration naturelle D. La recherche de nouveaux analogues nucléosidiques de configuration L apparaît ainsi prometteuse. Dans notre travail, nous nous sommes plus particulièrement intéressés aux dérivés de la L-2'-désoxyuridine substitués en position 5 de la nucléobase. La synthèse de ces composés a été réalisée à partir de la L-5-iodo-2'-désoxyuridine, un intermédiaire clé que nous avons préalablement obtenu à partir du L-ribose. Nous avons ensuite fonctionnalisé ce composé en position 5 via l'utilisation de réactions organopalladées. Les composés obtenus ont été évalués sur divers virus à ADN et à ARN, ainsi que sur des lignées cellulaires tumorales exprimant une enzyme modifiée de la désoxycytidine kinase, enzyme impliquée dans la métabolisation de nombreux nucléosides. Nous avons ensuite réalisé la synthèse des dérivés fluorés en position 2'-arabino. Dans ce cas, les analogues nucléosidiques ont été obtenus dans les deux configurations D et L afin de comparer leurs effets biologiques et de confirmer l'intérêt biologique de la configuration L.Nucleosidic analogues have proven their therapeutic efficiency and are commonly used in antiviral and cancer chemotherapies. Recently, it has been shown that nucleosidic analogues with a L non-natural configuration could present notable biological activities as well as their D counterparts. Therefore, discovery of new nucleosidic analogues with L configuration appears promising. In our study, we were interested in L-2'-deoxyuridine derivatives including modification on the position 5 of the nucleobase. The synthesis of these compounds was performed from the L-5-iodo-2'-deoxyuridine, a key intermediate which was synthesized from L-ribose. Then, we functionalized the 5 position of this intermediate using palladium-catalyzed cross-couplings. The desired compounds were tested on various DNA and RNA viruses, and on tumor cell lines expressing a modified deoxycytidine kinase, an enzyme responsible for the metabolism of a number of nucleosides. Finally, we synthesized nucleoside derivatives containing a fluorine atom on the 2'-arabino position. In this case, both compounds with D and L configuration were obtained, in order to compare their biological effects and to confirm the biological interest of L configuration
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