1,721,004 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
Investigating the influence of (Deoxy)fluorination on the lipophilicity of non-UV-active fluorinated alkanols and carbohydrates by a new log P determination method
No full textProperty tuning by fluorination is very effective for a number of purposes, and currently increasingly investigated for aliphatic compounds. An important application is lipophilicity (log?P) modulation. However, the determination of log?P is cumbersome for non-UV-active compounds. A new variation of the shake-flask log?P determination method is presented, enabling the measurement of log?P for fluorinated compounds with or without UV activity regardless of whether they are hydrophilic or lipophilic. No calibration curves or measurements of compound masses/aliquot volumes are required. With this method, the influence of fluorination on the lipophilicity of fluorinated aliphatic alcohols was determined, and the log?P values of fluorinated carbohydrates were measured. Interesting trends and changes, for example, for the dependence on relative stereochemistry, are reporte
Elaboration of compounds containing highly fluorinated groups to control and stabilize the formation of supramolecular assemblies
No full textLe fluor est d’un intérêt majeur dans le domaine pharmaceutique et celui des matériaux en raison de ses effets bénéfiques sur les propriétés physico-chimiques, la stabilité ou encore l’activité des molécules dans lesquelles il est incorporé. Au cours de ces travaux de thèse, nous avons cherché à élaborer des composés comportant des groupements hautement fluorés pour contrôler et stabiliser la formation d’assemblages supramoléculaires. Nous nous sommes intéressés à deux motifs fortement fluorés dignes d’intérêt. Le premier est l’hexafluoroisobutyle, un analogue fluoré de l’isobutyle comprenant six atomes de fluor, plus hydrophobe et plus volumineux. Le second motif étudié regroupe les architectures cis-polyfluorocyclohexyles pour lesquelles les atomes de fluor sont tous positionnés sur une seule face du cyclohexyle, leur conférant un caractère polaire très fort. Dans la première partie de ce travail, nous avons développé une méthodologie générale et directe d’hexafluoroisobutylation. Cette méthode mettant en jeux un électrophile fluoré liquide a été appliquée à différents substrats et s’est avérée particulièrement adaptée à la synthèse asymétrique de la (S)- et de la (R)-5,5,5,5’,5’,5’-hexafluoroleucine. En outre, nous avons étudié la substitution de la leucine par l’hexafluoroleucine au sein de peptides inhibant des interactions protéine-protéine et pour lesquels les leucines interagissent dans des cavités hydrophobes d’après des données cristallographiques. Pour certains peptides, le remplacement du motif isobutyle par le groupement hexafluoroisobutyle a permis d’augmenter significativement l’affinité des composés de l’ordre de la dizaine de nanomolaire. Par ailleurs, une part importante de ces travaux de thèse a été consacrée à l’incorporation du motif hexafluoroisobutyle au sein d’architectures supramoléculaires peptidomimétiques, du type oligourée, possédant des propriétés d’encapsulation dans le but de stabiliser l’assemblage et d’augmenter les propriétés de reconnaissance moléculaire. Cette étude a permis l’obtention de structures cristallographiques à haute résolution de faisceaux d’hélices fluorées hexamériques au sein desquels se trouve une cavité bordée de motifs hexafluoroisobutyles. Nous avons pu montrer que ce nouvel assemblage est plus stable que son analogue hydrogéné et que la fluoration peut augmenter fortement la stabilité de complexes hôte-invité. Nous avons également montré que la fluoration de la molécule invitée joue un rôle important sur la stabilité du complexe en utilisant des alcools aliphatiques avec des degrés de fluoration variables. Enfin, dans le but d’évaluer les propriétés supramoléculaires des motifs cis-polyfluorocyclohexyles, encore peu exploités, nous avons synthétisé des plateformes multivalentes sur lesquelles les cis-polyfluorocyclohexyles ont été greffés. Plusieurs structures cristallographiques de ces composés ont pu être obtenues montrant une structuration alignée, directionnelle et parallèle des cis-polyfluorocyclohexyles.Fluorine is of major interest in pharmaceuticals and materials due to its potential benefits on the physicochemical properties, stability, and activity of the molecules in which it is incorporated. In this thesis work, we aimed to develop compounds containing highly fluorinated groups to control and stabilize the formation of supramolecular assemblies. We were interested in two highly fluorinated motifs. The first is hexafluoroisobutyl, a fluorinated analog of isobutyl bearing six fluorine atoms, which is more hydrophobic and bulkier. The second scaffold studied was all-cis-polyfluorocyclohexyl motifs for which the fluorine atoms are all positioned on a single face of the cyclohexyl, giving them a high polarity. In the first part of this work, we developed a general and direct hexafluoroisobutylation methodology. This method involving a liquid fluorinated electrophile was applied to different substrates and proved to be particularly suitable for the asymmetric synthesis of (S)- and (R)-5,5,5,5',5',5'-hexafluoroleucine. In addition, we studied the substitution of leucine by hexafluoroleucine within peptides inhibiting protein-protein interactions and for which leucine side chains interact in hydrophobic cavities according to crystallographic data. For some peptides, replacing the isobutyl motif with the hexafluoroisobutyl group significantly increased the affinities of the compounds, with KD in the range of 15 nM. Furthermore, a significant part of this thesis work was devoted to the incorporation of the hexafluoroisobutyl motif into peptidomimetic supramolecular architectures, specifically N,N’-linked oligoureas with the objective of enhancing the stabilityze of the assembly and increasing its molecular recognition properties. We obtained high-resolution crystallographic structures of bundles of hexameric fluorinated helices in which a cavity decorated with hexafluoroisobutyl units is present. We showed that this new assembly is more stable than its hydrogenated analog and that fluorination can substantially increase the stability of host-guest complexes. We also showed that the fluorination of the guest molecule plays an important role in the stability of the complex by using aliphatic alcohols with varying degrees of fluorination. Finally, to assess the supramolecular properties of the relatively underexplored all-cis-polyfluorocyclohexyl motifs, we synthesized multivalent platforms onto which all-cis-polyfluorocyclohexyls have been grafted. Several crystallographic structures of the compounds were obtained, showing an aligned, directional and parallel structuration of the all-cis-polyfluorocyclohexyls
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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