1,720,955 research outputs found
Fabrication and optimization of optical resonators via an emulsion route for the elaboration of metasurfaces
No full textLe contrôle d'assemblages colloïdaux complexes peut mener à la fabrication de nano-objets possédant des propriétés de résonance optique spécifiques et originales, pouvant être utilisées pour contrôler la propagation de la lumière. Cette thèse vise ainsi à fabriquer et optimiser des nano-résonateurs optiques plasmoniques pour les utiliser comme briques de base de métasurfaces de Huygens, efficaces dans le domaine du visible pour diffuser la lumière de manière directionnelle. Ces résonateurs sont des assemblages denses de nanoparticules d’argent, appelés clusters. Leur production repose sur la formulation puis le séchage d’une émulsion, dont les gouttes confinent l’auto-assemblage des nanoparticules et permettent l’obtention de clusters finaux de géométrie et de structure contrôlées. Cette dernière dépend de plusieurs paramètres, dont le principal est la nature et la longueur du ligand des nanoparticules. Les clusters synthétisés sont caractérisés à l’aide de plusieurs techniques, permettant de déterminer leur taille, leur forme, la qualité de leur assemblage et leur densité en argent. Une étude optique de ces résonateurs permet de déterminer leurs propriétés d’interaction avec la lumière. Les résultats montrent la présence d’une réponse dipolaire magnétique forte, dont l’amplitude et la longueur d’onde sont similaires à celles de la réponse dipolaire électrique des résonateurs. Ceci leur permet de diffuser la lumière de façon directionnelle, vers l’avant, et donc d’agir comme des résonateurs de Huygens. De ce fait, des dépôts de clusters d’argent ont été élaborés au cours de cette thèse, dans le but d’obtenir des métasurfaces de Huygens, selon deux stratégies principales : la synthèse d’une dispersion de clusters puis son dépôt sur un substrat ; la synthèse et le dépôt simultanés des clusters sur un substrat. Cette dernière stratégie, impliquant le dépôt puis le séchage sur un substrat d’une émulsion contenant dans ses gouttes une suspension de nanoparticules d’argent, a permis d’obtenir des surfaces finales homogènes et densément recouvertes de clusters de Huygens. Leur étude optique a démontré qu’elles interagissent de manière intense et résonante avec la lumière incidente.The control of complex colloidal assemblies can lead to the fabrication of nano-objects with specific and original optical resonance properties, which can be used to control the propagation of light. The aim of this thesis is to fabricate and optimise plasmonic optical nano-resonators for use as building blocks for Huygens metasurfaces, which are effective in the visible range for scattering light directionally. These resonators are dense assemblies of silver nanoparticles, known as clusters. They are produced by formulating then drying an emulsion whose droplets confine the self-assembly of the nanoparticles and enable the final clusters to be obtained with a controlled geometry and structure. The latter depends on several parameters, the main one being the nature and length of the nanoparticle ligand. The synthesised clusters are characterised using several techniques to determine their size, shape, assembly quality and silver density. An optical study of these resonators was carried out to determine their interaction properties with light. The results show the presence of a strong magnetic dipolar response, the amplitude and wavelength of which are similar to those of the resonators' electrical dipolar response. This allows them to scatter light directionally, in a forward direction, and therefore to act like Huygens resonators. Therefore, deposits of silver clusters were developed in the course of this thesis, in order to obtain Huygens metasurfaces, using two main strategies: the synthesis of a dispersion of clusters and then their deposition on a substrate; the simultaneous synthesis and deposition of clusters on a substrate. The latter strategy, involving the deposition then drying on a substrate of an emulsion containing a suspension of silver nanoparticles in its droplets, resulted in homogeneous final surfaces densely covered with Huygens clusters. Their optical study showed that they interact intensely and resonantly with incident light
Fabrication et optimisation de résonateurs optiques par auto-assemblage en émulsion pour l’élaboration de métasurfaces
No full textThe control of complex colloidal assemblies can lead to the fabrication of nano-objects with specific and original optical resonance properties, which can be used to control the propagation of light. The aim of this thesis is to fabricate and optimise plasmonic optical nano-resonators for use as building blocks for Huygens metasurfaces, which are effective in the visible range for scattering light directionally. These resonators are dense assemblies of silver nanoparticles, known as clusters. They are produced by formulating then drying an emulsion whose droplets confine the self-assembly of the nanoparticles and enable the final clusters to be obtained with a controlled geometry and structure. The latter depends on several parameters, the main one being the nature and length of the nanoparticle ligand. The synthesised clusters are characterised using several techniques to determine their size, shape, assembly quality and silver density. An optical study of these resonators was carried out to determine their interaction properties with light. The results show the presence of a strong magnetic dipolar response, the amplitude and wavelength of which are similar to those of the resonators' electrical dipolar response. This allows them to scatter light directionally, in a forward direction, and therefore to act like Huygens resonators. Therefore, deposits of silver clusters were developed in the course of this thesis, in order to obtain Huygens metasurfaces, using two main strategies: the synthesis of a dispersion of clusters and then their deposition on a substrate; the simultaneous synthesis and deposition of clusters on a substrate. The latter strategy, involving the deposition then drying on a substrate of an emulsion containing a suspension of silver nanoparticles in its droplets, resulted in homogeneous final surfaces densely covered with Huygens clusters. Their optical study showed that they interact intensely and resonantly with incident light.Le contrôle d'assemblages colloïdaux complexes peut mener à la fabrication de nano-objets possédant des propriétés de résonance optique spécifiques et originales, pouvant être utilisées pour contrôler la propagation de la lumière. Cette thèse vise ainsi à fabriquer et optimiser des nano-résonateurs optiques plasmoniques pour les utiliser comme briques de base de métasurfaces de Huygens, efficaces dans le domaine du visible pour diffuser la lumière de manière directionnelle. Ces résonateurs sont des assemblages denses de nanoparticules d’argent, appelés clusters. Leur production repose sur la formulation puis le séchage d’une émulsion, dont les gouttes confinent l’auto-assemblage des nanoparticules et permettent l’obtention de clusters finaux de géométrie et de structure contrôlées. Cette dernière dépend de plusieurs paramètres, dont le principal est la nature et la longueur du ligand des nanoparticules. Les clusters synthétisés sont caractérisés à l’aide de plusieurs techniques, permettant de déterminer leur taille, leur forme, la qualité de leur assemblage et leur densité en argent. Une étude optique de ces résonateurs permet de déterminer leurs propriétés d’interaction avec la lumière. Les résultats montrent la présence d’une réponse dipolaire magnétique forte, dont l’amplitude et la longueur d’onde sont similaires à celles de la réponse dipolaire électrique des résonateurs. Ceci leur permet de diffuser la lumière de façon directionnelle, vers l’avant, et donc d’agir comme des résonateurs de Huygens. De ce fait, des dépôts de clusters d’argent ont été élaborés au cours de cette thèse, dans le but d’obtenir des métasurfaces de Huygens, selon deux stratégies principales : la synthèse d’une dispersion de clusters puis son dépôt sur un substrat ; la synthèse et le dépôt simultanés des clusters sur un substrat. Cette dernière stratégie, impliquant le dépôt puis le séchage sur un substrat d’une émulsion contenant dans ses gouttes une suspension de nanoparticules d’argent, a permis d’obtenir des surfaces finales homogènes et densément recouvertes de clusters de Huygens. Leur étude optique a démontré qu’elles interagissent de manière intense et résonante avec la lumière incidente
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
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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