1,720,958 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
Controlled hybridization of helical electroactive foldamers for the design of homo – and heteroduplexes
No full textLes foldamères de type oligoarylamide constituent une famille d’oligomères capables de se replier en structures hélicoïdales et de s’hybrider pour former des hélices doubles. L’objectif central de ce travail de thèse a consisté à pourvoir de telles espèces d’unités redox, afin de contrôler leur hybridation en homo – et en hétéroduplexes de manière sélective. Dans une première partie, un oligoarylamide fonctionnalisé par deux unités tétrathiafulvalène (TTF) via un espaceur amide rigide et court a été synthétisé. Cinq structures cristallographiques différentes de ce foldamère sous sa forme ‘hélice simple’ ont été obtenues. L’apparente stabilité de cet arrangement à l’état neutre a pu être confirmée par diverses études spectroscopiques en solution. De manière originale, il a été montré que l’oxydation des unités TTF déclenche l’hybridation de ce foldamère, i.e. la formation d’hélices doubles, via la formation de dimères de radicaux –cations. Dans une seconde partie, une série de foldamères dotés de groupements donneurs ou accepteurs de densité électronique a été synthétisée. Ces oligomères se sont avérés piégés cinétiquement dans leur forme ‘hélice simple’ du fait d’interactions intramoléculaires. Ainsi, la présence du connecteur triazole explique, au moins en partie, l’obtention d’un système hors équilibre, bien que la contribution d’interactions aromatiques intramoléculaires ne puisse être exclue.Ainsi, les foldamères de cette famille tendent à former des polymères supramoléculaires lors de leur première dispersion. A travers une étude relativement détaillée, il a été montré que le système était piégé cinétiquement à température ambiante et que la composition du milieu n’évoluait pas avec le temps. En revanche, un simple chauffage à 45°C (dans le chloroforme) permet l’obtention d’un système métastable, qui permet progressivement le déplacement de l’équilibre vers la forme hybridée.Oligoarylamide foldamers represent a family of oligomers that are capable of folding into helical structures and hybridizing to form double helices through non –covalent interactions. The central objective of this thesis work consisted in designing electroactive helical foldamers to control their hybridization into homo – or heteroduplexes in a selective manner. In this context, a strand functionalized with two tetrathiafulvalene (TTF) units via a rigid and short amide spacer was synthesized. Five different crystallographic structures of this foldamer in its 'single helix' form were obtained. The apparent stability of this arrangement in the neutral state was confirmed through various spectroscopic studies in solution. Interestingly, the oxidation of the TTF units triggered the hybridization of this foldamer, through the formation of radical cation dimers. In a second part, foldamers endowed with electron –donating groups or electron –withdrawing acceptors was synthesized. These oligomers were found to be kinetically trapped in their 'single helix' form due to intramolecular interactions. Thus, the presence of the triazole motif explains, at least in part, why an out –of–equilibrium system is obtained. As a result, these foldamers tend to form supramolecular polymers along their initial dispersion. Through a relatively detailed study, it was shown that at room temperature, the system was kinetically trapped, and the composition of the medium did not evolve over time. However, a simple heating to 45°C (in chloroform) allowed for reaching a metastable system, which gradually towards the hybridized form
Hybridation contrôlée de foldamères hélicoïdaux électroactifs pour la conception d’homo– et d’hétéroduplexes
No full textOligoarylamide foldamers represent a family of oligomers that are capable of folding into helical structures and hybridizing to form double helices through non –covalent interactions. The central objective of this thesis work consisted in designing electroactive helical foldamers to control their hybridization into homo – or heteroduplexes in a selective manner. In this context, a strand functionalized with two tetrathiafulvalene (TTF) units via a rigid and short amide spacer was synthesized. Five different crystallographic structures of this foldamer in its 'single helix' form were obtained. The apparent stability of this arrangement in the neutral state was confirmed through various spectroscopic studies in solution. Interestingly, the oxidation of the TTF units triggered the hybridization of this foldamer, through the formation of radical cation dimers. In a second part, foldamers endowed with electron –donating groups or electron –withdrawing acceptors was synthesized. These oligomers were found to be kinetically trapped in their 'single helix' form due to intramolecular interactions. Thus, the presence of the triazole motif explains, at least in part, why an out –of–equilibrium system is obtained. As a result, these foldamers tend to form supramolecular polymers along their initial dispersion. Through a relatively detailed study, it was shown that at room temperature, the system was kinetically trapped, and the composition of the medium did not evolve over time. However, a simple heating to 45°C (in chloroform) allowed for reaching a metastable system, which gradually towards the hybridized form.Les foldamères de type oligoarylamide constituent une famille d’oligomères capables de se replier en structures hélicoïdales et de s’hybrider pour former des hélices doubles. L’objectif central de ce travail de thèse a consisté à pourvoir de telles espèces d’unités redox, afin de contrôler leur hybridation en homo – et en hétéroduplexes de manière sélective. Dans une première partie, un oligoarylamide fonctionnalisé par deux unités tétrathiafulvalène (TTF) via un espaceur amide rigide et court a été synthétisé. Cinq structures cristallographiques différentes de ce foldamère sous sa forme ‘hélice simple’ ont été obtenues. L’apparente stabilité de cet arrangement à l’état neutre a pu être confirmée par diverses études spectroscopiques en solution. De manière originale, il a été montré que l’oxydation des unités TTF déclenche l’hybridation de ce foldamère, i.e. la formation d’hélices doubles, via la formation de dimères de radicaux –cations. Dans une seconde partie, une série de foldamères dotés de groupements donneurs ou accepteurs de densité électronique a été synthétisée. Ces oligomères se sont avérés piégés cinétiquement dans leur forme ‘hélice simple’ du fait d’interactions intramoléculaires. Ainsi, la présence du connecteur triazole explique, au moins en partie, l’obtention d’un système hors équilibre, bien que la contribution d’interactions aromatiques intramoléculaires ne puisse être exclue.Ainsi, les foldamères de cette famille tendent à former des polymères supramoléculaires lors de leur première dispersion. A travers une étude relativement détaillée, il a été montré que le système était piégé cinétiquement à température ambiante et que la composition du milieu n’évoluait pas avec le temps. En revanche, un simple chauffage à 45°C (dans le chloroforme) permet l’obtention d’un système métastable, qui permet progressivement le déplacement de l’équilibre vers la forme hybridée
Hybridation contrôlée de foldamères hélicoïdaux électroactifs pour la conception d’homo– et d’hétéroduplexes
No full textOligoarylamide foldamers represent a family of oligomers that are capable of folding into helical structures and hybridizing to form double helices through non –covalent interactions. The central objective of this thesis work consisted in designing electroactive helical foldamers to control their hybridization into homo – or heteroduplexes in a selective manner. In this context, a strand functionalized with two tetrathiafulvalene (TTF) units via a rigid and short amide spacer was synthesized. Five different crystallographic structures of this foldamer in its 'single helix' form were obtained. The apparent stability of this arrangement in the neutral state was confirmed through various spectroscopic studies in solution. Interestingly, the oxidation of the TTF units triggered the hybridization of this foldamer, through the formation of radical cation dimers. In a second part, foldamers endowed with electron –donating groups or electron –withdrawing acceptors was synthesized. These oligomers were found to be kinetically trapped in their 'single helix' form due to intramolecular interactions. Thus, the presence of the triazole motif explains, at least in part, why an out –of–equilibrium system is obtained. As a result, these foldamers tend to form supramolecular polymers along their initial dispersion. Through a relatively detailed study, it was shown that at room temperature, the system was kinetically trapped, and the composition of the medium did not evolve over time. However, a simple heating to 45°C (in chloroform) allowed for reaching a metastable system, which gradually towards the hybridized form.Les foldamères de type oligoarylamide constituent une famille d’oligomères capables de se replier en structures hélicoïdales et de s’hybrider pour former des hélices doubles. L’objectif central de ce travail de thèse a consisté à pourvoir de telles espèces d’unités redox, afin de contrôler leur hybridation en homo – et en hétéroduplexes de manière sélective. Dans une première partie, un oligoarylamide fonctionnalisé par deux unités tétrathiafulvalène (TTF) via un espaceur amide rigide et court a été synthétisé. Cinq structures cristallographiques différentes de ce foldamère sous sa forme ‘hélice simple’ ont été obtenues. L’apparente stabilité de cet arrangement à l’état neutre a pu être confirmée par diverses études spectroscopiques en solution. De manière originale, il a été montré que l’oxydation des unités TTF déclenche l’hybridation de ce foldamère, i.e. la formation d’hélices doubles, via la formation de dimères de radicaux –cations. Dans une seconde partie, une série de foldamères dotés de groupements donneurs ou accepteurs de densité électronique a été synthétisée. Ces oligomères se sont avérés piégés cinétiquement dans leur forme ‘hélice simple’ du fait d’interactions intramoléculaires. Ainsi, la présence du connecteur triazole explique, au moins en partie, l’obtention d’un système hors équilibre, bien que la contribution d’interactions aromatiques intramoléculaires ne puisse être exclue.Ainsi, les foldamères de cette famille tendent à former des polymères supramoléculaires lors de leur première dispersion. A travers une étude relativement détaillée, il a été montré que le système était piégé cinétiquement à température ambiante et que la composition du milieu n’évoluait pas avec le temps. En revanche, un simple chauffage à 45°C (dans le chloroforme) permet l’obtention d’un système métastable, qui permet progressivement le déplacement de l’équilibre vers la forme hybridée
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
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