1,720,963 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
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
Manganese and rhenium complexes for (de)-hydrogenation reactions
No full textDepuis la découverte de l'efficacité des catalyseurs de manganèse(I) dans les réactions d'hydrogénation en 2016, ce domaine de recherche a connu une évolution exponentielle. Un grand nombre de systèmes catalytiques a été développé en jouant sur la nature des ligands, le choix de la source d'hydrogène et les conditions réactionnelles. Ces recherches ont conduit à des progrès significatifs en termes d'activité catalytique, de sélectivité et de champ d'application. L’objectif de ce travail doctoral était de développer de nouveaux catalyseurs bien définis de manganèse pour réaliser efficacement des réactions d’hydrogénation (asymétrique), par voie directe en présence de H2 ou par transfert d’hydrogène, de liaisons polaires et apolaires. Le premier chapitre résume les avancés récentes dans le domaine des réactions d’hydrogénation catalysée par le manganèse. La deuxième partie de ce travail porte sur l’utilisation de complexes chiraux de Mn(I) en réduction asymétrique de cétones par transfert d'hydrogène. Cette étude a permis d’identifier rapidement, par un criblage in-situ de ligands amino-phosphines commerciaux, un ligand particulièrement actif et sélectif en transfert d'hydrogénation asymétrique avec des énantiosélectivités allant jusqu’à 99%. La troisième partie de ce travail est consacrée à la préparation d'une série de complexes de manganèse(I) supporté par des ligands bidentes facilement accessibles. Ces complexes ont conduit à des résultats catalytiques prometteurs pour la réduction d’esters, de cétones et d’alcènes terminaux. La dernière partie de ce travail de thèse décrit l’utilisation du méthanol, comme source durable de carbone C1, pour les réactions de C-alkylation de cétones. Ces dernières réactions ont été promues par des complexes de rhénium.Since the discovery of the efficiency of manganese(I) catalysts in direct hydrogenation and hydrogen transfer reactions in 2016, this field of research has undergone a significant evolution. A large number of catalytic systems has been developed by playing with ligand design, hydrogen source selection, and the reaction conditions, which resulted in significant progress in terms of catalytic activity, selectivity and application scope. The objective of this PhD work was to develop new well-defined manganese catalysts to efficiently perform hydrogenation and asymmetric hydrogen transfer reactions of polar and apolar bonds with readily available ligands. The first chapter summarizes the recent advances in manganese-catalyzed hydrogenations. The second part of this work deals with the use of chiral manganese(I) complexes in the asymmetric reduction of ketones by hydrogen transfer. This study allowed the rapid identification, by in-situ screening of commercial amino-phosphine ligands, of a particularly active and selective ligand for asymmetric hydrogen transfer with enantioselectivities up to 99%. The corresponding well-defined complex has been prepared and its catalytic activity was shown to be similar to the one of in-situ system. The third part of this work is devoted to the preparation of a series of manganese(I) complexes supported by readily available bidentate ligands. These complexes have led to promising catalytic results for the reduction of esters, ketones and terminal alkenes. The last part of this thesis describes the use of methanol, as a sustainable source of C1 carbon, for C-alkylation reactions of ketones through hydrogen borrowing reaction. In this last case, we have selected rhenium, the heavier congener of manganese, as meta
Complexes de manganèse et de rhénium pour les réactions de (dé)-hydrogénation
No full textSince the discovery of the efficiency of manganese(I) catalysts in direct hydrogenation and hydrogen transfer reactions in 2016, this field of research has undergone a significant evolution. A large number of catalytic systems has been developed by playing with ligand design, hydrogen source selection, and the reaction conditions, which resulted in significant progress in terms of catalytic activity, selectivity and application scope. The objective of this PhD work was to develop new well-defined manganese catalysts to efficiently perform hydrogenation and asymmetric hydrogen transfer reactions of polar and apolar bonds with readily available ligands. The first chapter summarizes the recent advances in manganese-catalyzed hydrogenations. The second part of this work deals with the use of chiral manganese(I) complexes in the asymmetric reduction of ketones by hydrogen transfer. This study allowed the rapid identification, by in-situ screening of commercial amino-phosphine ligands, of a particularly active and selective ligand for asymmetric hydrogen transfer with enantioselectivities up to 99%. The corresponding well-defined complex has been prepared and its catalytic activity was shown to be similar to the one of in-situ system. The third part of this work is devoted to the preparation of a series of manganese(I) complexes supported by readily available bidentate ligands. These complexes have led to promising catalytic results for the reduction of esters, ketones and terminal alkenes. The last part of this thesis describes the use of methanol, as a sustainable source of C1 carbon, for C-alkylation reactions of ketones through hydrogen borrowing reaction. In this last case, we have selected rhenium, the heavier congener of manganese, as metal.Depuis la découverte de l'efficacité des catalyseurs de manganèse(I) dans les réactions d'hydrogénation en 2016, ce domaine de recherche a connu une évolution exponentielle. Un grand nombre de systèmes catalytiques a été développé en jouant sur la nature des ligands, le choix de la source d'hydrogène et les conditions réactionnelles. Ces recherches ont conduit à des progrès significatifs en termes d'activité catalytique, de sélectivité et de champ d'application. L’objectif de ce travail doctoral était de développer de nouveaux catalyseurs bien définis de manganèse pour réaliser efficacement des réactions d’hydrogénation (asymétrique), par voie directe en présence de H2 ou par transfert d’hydrogène, de liaisons polaires et apolaires. Le premier chapitre résume les avancés récentes dans le domaine des réactions d’hydrogénation catalysée par le manganèse. La deuxième partie de ce travail porte sur l’utilisation de complexes chiraux de Mn(I) en réduction asymétrique de cétones par transfert d'hydrogène. Cette étude a permis d’identifier rapidement, par un criblage in-situ de ligands amino-phosphines commerciaux, un ligand particulièrement actif et sélectif en transfert d'hydrogénation asymétrique avec des énantiosélectivités allant jusqu’à 99%. La troisième partie de ce travail est consacrée à la préparation d'une série de complexes de manganèse(I) supporté par des ligands bidentes facilement accessibles. Ces complexes ont conduit à des résultats catalytiques prometteurs pour la réduction d’esters, de cétones et d’alcènes terminaux. La dernière partie de ce travail de thèse décrit l’utilisation du méthanol, comme source durable de carbone C1, pour les réactions de C-alkylation de cétones. Ces dernières réactions ont été promues par des complexes de rhénium
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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