1,720,966 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
Organosilver(III) compounds for trifluoromethylations
No full textLes molécules trifluorométhylées sont largement utilisées dans les préparations pharmaceutiques et agrochimiques en raison de leurs propriétés particulières comme principes bioactifs. Cependant, la fonctionnalisation tardive des structures organiques avec ce groupe électroattracteur est particulièrement difficile et les méthodes actuellement utilisées à l’échelle industrielle pour réaliser de tels composés reposent sur des réactions découvertes il y a près de 100 ans. Récemment, d’autres méthodes visant à réaliser cette transformation cruciale ont été découvertes, mais le problème de la trifluorométhylation sélective et efficace des composés organiques à un stade avancé de leur synthèse n’est toujours pas résolu. Les espèces organométalliques à haute valence se sont révélées efficaces dans la création des liaisons C-CF3, mais les études dans ce domaine n’en sont encore qu’à leur début en raison des difficultés rencontrées dans la synthèse, la caractérisation et l’étude de la réactivité de ces composés exotiques.Dans ce contexte, il est crucial d’avoir un accès fiable aux espèces organométalliques à haute valence, et c’est pourquoi cette Thèse de doctorat se concentre sur l’accès aux complexes organo-argentés(III) trifluorométhylés. La résolution d’un problème présent dans la littérature depuis 30 ans, une nouvelle voie de synthèse sûre et efficace pour obtenir l’anion homoleptique trifluorométhyl de argent(III) [AgIII(CF3)4]- a été développée. Cette avancée cruciale a permis de démontrer l’utilité synthétique de l’anion AgIII pour accéder à une classe de composés organo-argentés(III) neutres dont la formule générale AgIII(CF3)3(L). Les propriétés de ces complexes sous-explorés ont été étudiées, en particulier l’acidité apicale du centre métallique permettant la coordination des ligands de type L.Ces composés organo-argentés(III) neutres peuvent échanger efficacement de ligand et se sont révélés compétents pour la trifluorométhylation. Leur application dans la trifluorométhylation de dérivés aryle borés a été explorée, établissant la robustesse et l’applicabilité générale de la transformation pour obtenir les benzotrifluorures correspondants. Des études du mécanisme de la réaction et l’isolement d’un anion [AgIII(CF3)3(aryl)]- ont permis de prouver la voie d’élimination réductrice à 2e- intervenant dans la transformation. Ce schéma de réactivité ne semble pas se limiter aux dérivés du aryle borés et à la trifluorométhylation du cycle aromatique, mais il peut être étendu à la formation de liaisons Hétéroatome-CF3.)Trifluoromethylated molecules are widely used in pharmaceutical and agrochemical preparations due to their peculiar properties as bioactive principles. However, late-stage functionalization of organic scaffolds with this particularly electron-withdrawing group is remarkably challenging and the methods currently used on industrial scale to achieve such compounds rely on reactions discovered almost 100 years ago. Recently, more methods to achieve such crucial transformation are being discovered, yet the problem of efficient and selective late-stage trifluoromethylation of organic scaffolds remains unsolved. High-valent organometallic species have proven effective in the forging of C-CF3 bonds but studies in this field are still at their infancy due to the difficulties encountered in the synthesis, characterization and reactivity study of such exotic compounds.In this context, it is crucial to have a reliable access to high-valent organometallic species, and therefore this Ph.D. Thesis focuses on the access to trifluoromethyl organosilver(III) complexes. Solving a problem present in the literature for 30 years, a new, safe, and efficient synthetic pathway to forge the trifluoromethyl silver(III) anion [AgIII(CF3)4]− has been developed. This advancement allowed to demonstrate the synthetic utility of the AgIII anion to access a class of neutral organosilver(III) compounds of the general formula AgIII(CF3)3(L). The properties of such underexplored complexes have been investigated alongside the proof for the apical acidity of neutral square-planar AgIII complexes, allowing the coordination of L-type ligands. These neutral organosilver(III) compounds undergo efficient ligand exchange and proved to be trifluoromethylating-competent. Their application in the trifluoromethylation of aryl boron derivatives has been explored, establishing the robustness and general applicability of this transformation to obtain the corresponding benzotrifluorides. Mechanistic studies including the isolation of an [AgIII(CF3)3(aryl)]− anion allowed to prove the 2e− reductive elimination pathway occurring in the transformation. This pattern of reactivity appears to be not limited only to arylboron derivatives and to the trifluoromethylation of the aromatic ring, but it can be extended to the formation of F3C-Heteroatom- bonds
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Compuestos organometálicos en estado de oxidación inusualmente elevado. Utilización en la trifluorometilación oxidativa de derivados arilboro.
No full textInternational audienceAromatic trifluoromethylation enabled by metal complexes is highly challenging yet extremely relevant for drug discovery and agrochemical design. First discovered in 2010, the oxidative trifluoromethylation represents an original approach to these valuable chemicals (aryl–CF3) and involves the key participation of late transition metals in high oxidation state, in particular coinage metals [Cu(III)CF3 and Ag(III)CF3 species]. We herein provide a general overview on this topic, and compile the main contributions regarding the oxidative trifluoromethylation of arylboron derivatives mediated by well-defined Cu(III) and Ag(III) complexes
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