1,721,046 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
Exploiting halogen bonding interactions in high-performance liquid chromatography enantioseparations
No full textHigh-performance liquid chromatography (HPLC) on chiral stationary phases (CSPs) is a widely-known tool for producing pure enantiomers. Inside the chiral column, the enantioseparation is driven by the ability of the CSP to distinguish between two introduced enantiomers. The understanding of the chiral recognition mechanisms contributes to design successful enantioseparations.
Recently, the enantioseparation results of 2,2’-dichloro-3-iodo-5-bromo-5’-halo-4,4’-bipyridines suggested that a halogen bonding (XB) interaction involving iodine as electrophilic XB donor and the carbamate carbonyl group of the polysaccharide-based selector as XB acceptor reasonably drives the recognition mechanism.
With the aim to verify the effectiveness of the XB interaction in HPLC enantioseparation of compounds characterized by different topologies compared to the 4,4’-bipyridine derivatives, we also found that the enantioseparation of 2-halo and 2,3-dihalosubstituted benzonorbornadienes appears XB-dependent
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
Chalcogen bonds and tellorium salts : synthesis, studies and catalysis
No full textCe travail de thèse s’articule autour de la synthèse de dérivés tellurés, les sels de telluronium, de leur étude à l’état solide et en solution, avec le but de développer des catalyseurs efficaces pour l’organocatalyse.Dans un premier temps, la synthèse de sels de telluronium achiraux a été réalisée et leur aptitude à former des interactions non covalentes basées sur des trous-σ, appelées liaisons chalcogène, a été étudiée aussi bien à l'état solide qu’en solution. En combinant diverses techniques d’analyse, ces investigations ont permis de mieux comprendre la thermodynamique de formation de ces interactions encore peu explorées en solu-tion.De plus, étant donné que la chiralité autour des liaisons chalcogène reste encore inexplorée, la synthèse de sels de telluronium chiraux a également été explorée à travers différentes stratégies, afin d'élargir les possibi-lités dans ce domaine émergeant de la catalyse asymétrique.Enfin, les meilleurs candidats achiraux ont été utilisés en organocatalyse dans quelques réactions (bromation d’aromatiques, halogénation d’alcènes et réaction de Povarov) afin de démontrer leur efficacité en tant qu’organocatalyseurs.This PhD work focuses on the synthesis of tellurium derivatives, telluronium salts, and their study both in the solid-state and in solution, with the aim to develop efficient catalysts for organocatalysis.First, the synthesis of achiral telluronium salts was performed and their abilities to form non-covalent interactions based on σ-holes, known as chalcogen bonds, were studied both in the solid-state and in solution. By combining various analytical techniques, these investigations provided a better understanding of the thermodynamics behind the formation of these interactions, which remain largely unexplored in solution.Furthermore, since the chirality around chalcogen bonds remains largely unexplored, the synthesis of chiral telluronium salts was also addressed and investigated through various strategies in order to expand the possibilities in this emerging field of asymmetric catalysis.Finally, from solid-state and solution studies, the best achiral candidates were used in organocatalysis for various reactions (bromination of arenes, halogenation of alkenes and the Povarov reaction) to demonstrate their efficiency as organocatalysts
Study of σ-hole interactions in solution : design, synthesis and applications of new halogen and chalcogen bond donors
No full textCe travail de thèse s’articule autour de la synthèse de nouveaux donneurs de trous-σ, leur étude en solution ainsi que leur mise en application en organocatalyse.Dans un premier temps, l’aptitude des chalcogènes (soufre, sélénium et tellure) à former des interactions non covalentes basées sur un trou-σ a été étudiée en solution. Pour cela, une étude par chromatographie en phase liquide à haute performance sur phase stationnaire chirale avec des 4,4’-bipyridines soufrées et séléniées a été réalisée pour montrer la présence de liaison chalcogène stéréosélective en solution. De plus, une autre étude par spectroscopie de résonance magnétique nucléaire a été menée afin de mettre cette fois-ci en lumière la présence de liaisons chalcogène basées sur l’atome de tellure dans différents composés organotellurés.Enfin, à partir de leur étude en solution, les meilleurs donneurs de trou-σ ont été utilisés en organocatalyse dans diverses réactions (bromation, bromocyclisation, aza-Diels-Alder, Ritter) afin de démontrer leur efficacité en tant qu’organocatalyseur.This PhD work is articulated around the synthesis of new σ-holes donors, their study in solution and their practical use in chemistry such as orgnanocatalysis.Initially, chalcogen ability to form σ-hole based non covalent interactions was studied in solution. A study was performed with chalcogenated 4,4’-bipyridines by using high-performance liquid chromatography and chiral stationary phase, in order to detect stereoselective chalcogen bonding in solution. Furthermore, a second study was performed with organotellurium compounds by using nuclear magnetic resonance spectroscopy.Finally, based on results previously observed in solution, best σ-hole donors were used in organocatalysis in various reactions (bromination, bromocyclization, aza-Diels-Alder, Ritter) to demonstrate their efficiency as organocatalysts
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