1,720,962 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
Hybrid systems development combining liquid crystals and functionalised glasses
No full textLes objectifs de ce doctorat sont de développer des dispositifs optiques originaux intégrant verres fonctionnalisés et cristaux liquides (CL). Ces travaux comportent deux parties distinctes : un système 1D basé sur la conception de fibres optiques multi-matériaux et un système 2D planaire utilisant des surfaces vitreuses polarisées électriquement. Préalablement, une méthode de caractérisation avancée basée sur la spectroscopie micro-Raman polarisée a été développée dans le but de caractériser l’orientation au sein de ces différents systèmes. Cette approche permet des mesures dans le volume à l’échelle micrométrique. Cette méthode d’imagerie donne également accès aux calculs du paramètre d’ordre et de la fonction de distribution d’orientation pour une évaluation quantitative du degré d’alignement des CL. Le premier système est un atténuateur optique variable (AOV) fibré composite intégrant verre, métal et CL, dont le but est d’utiliser la réponse électro-optique de la mésophase pour moduler la lumière transmise par le coeur de la fibre. Les études par imagerie Raman 3D de l’orientation des CL au sein de capillaires simples ont permis de mettre en évidence une organisation radiale des molécules. Elles sont perpendiculaires aux parois à l’ancrage et se réorientent dans l’axe du capillaire au centre de la cavité. De plus, il a été mis en avant que le degré d’orientation et l’amplitude de réorientation sous champ électrique, paramètres fondamentaux pour un bon fonctionnement de l’AOV, sont très dépendant de la taille du capillaire. Cette étude a donc permis de tirer des conclusions concernant les paramètres géométriques à envisager pour la conception du dispositif final. Le système 2D combine des surfaces de verres microstructurées par poling thermique et des cristaux liquides afin d’induire une organisation périodique de la mésophase, et donc des caractéristiques optiques du système. Un traitement de micro-poling assisté par plasma a été mis au point par l’utilisation d’une grille micrométrique de nickel comme anode. On observe alors une corrélation géométrique entre (i) les modifications de la structure et de la composition du verre sondées par Raman et spectroscopie à rayon X (EDX), (ii) l'emplacement et les composantes des champs statiques figés dans le verre mesurés par génération de seconde harmonique (SHG) et (iii) les domaines d’alignements homéotropes ou planaires des CL. Ces travaux constituent une preuve de concept démontrant qu’un contrôle précis de l’organisation des CL peut être obtenu par la maitrise des propriétés électriques de surface d’un substrat de verre. Ils soulignent également l'importance des décharges plasma contrôlées spatialement le long du motif d'électrode afin de promouvoir les effets de polarisation électrique dans le plan, qui sont essentiels pour appliquer aux CL des alignements planaires.The objectives of this PhD are to develop original optical devices integrating functionalised glasses and liquid crystals (LC). This work includes two distinct parts: a 1D system based on multi-material optical fibre design and a 2D planar system using electrically polarised glass surfaces. Previously, an advanced characterisation method based on polarised micro-Raman spectroscopy has been developed in order to characterise the orientation within these different systems. This approach allows measurements in the volume at the micrometre scale. This imaging method also provides access to order parameter and orientation distribution function calculations for a quantitative assessment of the degree of LC alignment. The first system is a composite fibre variable optical attenuator (VOA) integrating glass, metal, and LC, whose purpose is to use the electro-optical response of the mesophase to modulate the light transmitted through the fibre core. 3D Raman imaging studies of the LC orientation within single capillaries have revealed a radial organisation of the molecules. They are perpendicular to the walls at the anchorage and reorient themselves in the axis of the capillary at the centre of the cavity. Moreover, it was shown that the orientation degree and the reorientation amplitude under electric field, fundamental parameters for a good performance of the VOA, are very dependent on the capillary size. This study has therefore allowed us to draw conclusions concerning the geometrical parameters to be considered for the design of the final device. The 2D system combines microstructured glass surfaces by thermal poling and liquid crystals in order to induce a periodic mesophase organisation, and thus the optical characteristics of the system. A plasma-assisted micro-poling treatment has been developed by using a micrometric nickel grid as anode. A geometric correlation is then observed between (i) changes in glass structure and composition probed by Raman and X-ray spectroscopy (EDX), (ii) the location and components of static fields frozen in the glass measured by second harmonic generation (SHG), and (iii) the homeotropic or planar alignment domains of LC. This work constitutes a proof of concept demonstrating that a precise control of the LC organisation can be achieved by controlling the surface electrical properties of a glass substrate. They also highlight the importance of spatially controlled plasma discharges along the electrode pattern to promote in-plane electrical polarisation effects, which are essential to induce planar LC alignments
Développement de systèmes optiques combinant verres fonctionnalisés et cristaux liquides
No full textThe objectives of this PhD are to develop original optical devices integrating functionalised glasses and liquid crystals (LC). This work includes two distinct parts: a 1D system based on multi-material optical fibre design and a 2D planar system using electrically polarised glass surfaces. Previously, an advanced characterisation method based on polarised micro-Raman spectroscopy has been developed in order to characterise the orientation within these different systems. This approach allows measurements in the volume at the micrometre scale. This imaging method also provides access to order parameter and orientation distribution function calculations for a quantitative assessment of the degree of LC alignment. The first system is a composite fibre variable optical attenuator (VOA) integrating glass, metal, and LC, whose purpose is to use the electro-optical response of the mesophase to modulate the light transmitted through the fibre core. 3D Raman imaging studies of the LC orientation within single capillaries have revealed a radial organisation of the molecules. They are perpendicular to the walls at the anchorage and reorient themselves in the axis of the capillary at the centre of the cavity. Moreover, it was shown that the orientation degree and the reorientation amplitude under electric field, fundamental parameters for a good performance of the VOA, are very dependent on the capillary size. This study has therefore allowed us to draw conclusions concerning the geometrical parameters to be considered for the design of the final device. The 2D system combines microstructured glass surfaces by thermal poling and liquid crystals in order to induce a periodic mesophase organisation, and thus the optical characteristics of the system. A plasma-assisted micro-poling treatment has been developed by using a micrometric nickel grid as anode. A geometric correlation is then observed between (i) changes in glass structure and composition probed by Raman and X-ray spectroscopy (EDX), (ii) the location and components of static fields frozen in the glass measured by second harmonic generation (SHG), and (iii) the homeotropic or planar alignment domains of LC. This work constitutes a proof of concept demonstrating that a precise control of the LC organisation can be achieved by controlling the surface electrical properties of a glass substrate. They also highlight the importance of spatially controlled plasma discharges along the electrode pattern to promote in-plane electrical polarisation effects, which are essential to induce planar LC alignments.Les objectifs de ce doctorat sont de développer des dispositifs optiques originaux intégrant verres fonctionnalisés et cristaux liquides (CL). Ces travaux comportent deux parties distinctes : un système 1D basé sur la conception de fibres optiques multi-matériaux et un système 2D planaire utilisant des surfaces vitreuses polarisées électriquement. Préalablement, une méthode de caractérisation avancée basée sur la spectroscopie micro-Raman polarisée a été développée dans le but de caractériser l’orientation au sein de ces différents systèmes. Cette approche permet des mesures dans le volume à l’échelle micrométrique. Cette méthode d’imagerie donne également accès aux calculs du paramètre d’ordre et de la fonction de distribution d’orientation pour une évaluation quantitative du degré d’alignement des CL. Le premier système est un atténuateur optique variable (AOV) fibré composite intégrant verre, métal et CL, dont le but est d’utiliser la réponse électro-optique de la mésophase pour moduler la lumière transmise par le coeur de la fibre. Les études par imagerie Raman 3D de l’orientation des CL au sein de capillaires simples ont permis de mettre en évidence une organisation radiale des molécules. Elles sont perpendiculaires aux parois à l’ancrage et se réorientent dans l’axe du capillaire au centre de la cavité. De plus, il a été mis en avant que le degré d’orientation et l’amplitude de réorientation sous champ électrique, paramètres fondamentaux pour un bon fonctionnement de l’AOV, sont très dépendant de la taille du capillaire. Cette étude a donc permis de tirer des conclusions concernant les paramètres géométriques à envisager pour la conception du dispositif final. Le système 2D combine des surfaces de verres microstructurées par poling thermique et des cristaux liquides afin d’induire une organisation périodique de la mésophase, et donc des caractéristiques optiques du système. Un traitement de micro-poling assisté par plasma a été mis au point par l’utilisation d’une grille micrométrique de nickel comme anode. On observe alors une corrélation géométrique entre (i) les modifications de la structure et de la composition du verre sondées par Raman et spectroscopie à rayon X (EDX), (ii) l'emplacement et les composantes des champs statiques figés dans le verre mesurés par génération de seconde harmonique (SHG) et (iii) les domaines d’alignements homéotropes ou planaires des CL. Ces travaux constituent une preuve de concept démontrant qu’un contrôle précis de l’organisation des CL peut être obtenu par la maitrise des propriétés électriques de surface d’un substrat de verre. Ils soulignent également l'importance des décharges plasma contrôlées spatialement le long du motif d'électrode afin de promouvoir les effets de polarisation électrique dans le plan, qui sont essentiels pour appliquer aux CL des alignements planaires
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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