1,721,021 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
Modélisation, développement et test d'une caméra plasma imprimée en 3D pour les mesures spatiales in-situ
No full textLes principaux phénomènes régissant la dynamique des plasmas spatiaux, que ce soit l'accélération des particules chargées, la reconnection magnétique ou la dissipation turbulente de l'énergie électromagnétique, sont de nature multi-échelle. Afin de comprendre leur rôle dans le fonctionnement du système Soleil-Terre, que ce soit dans le vent solaire, à la magnétopause ou dans la magnétosphère terrestre, il est indispensable de développer une instrumentation à la fois compacte et performante qui permette le déploiement de constellations de satellites. Cependant, les instruments de référence utilisés pour mesurer la distribution en énergie des particules chargées ont un champ de vue limité. L'ajout de systèmes de déflection électrostatique contourne cette limitation avec l'inconvénient d'alourdir ces instruments, de ralentir leur cadence de mesure et finalement de réduire leur performance. La multiplication des capteurs est alors nécessaire pour recouvrir les performances souhaitées, avec un impact sur le dimensionnement des satellites et finalement sur le nombre de satellites pouvant être déployés. La caractérisation des flux de particules chargées pour l'étude de la météorologie de l'espace souffre des mêmes limitations, celle-ci étant réalisée avec des instruments compacts et au champ de vue limité.La première étape de ce projet de recherche a consisté à développer une méthode de conception d'une nouvelle gamme de spectromètres plasmas qui dépassent ces limitations. Les spectromètres étudiés reposent sur une topologie torique innovante, offrant un champ de vue hémisphérique instantané qui évite l'utilisation de déflecteurs électrostatiques. Leur système de détection planaire font d'eux de véritables caméras plasmas. Les méthodes développées ont permis la génération numérique et la caractérisation par simulation d'un large éventail de caméras plasmas avec différentes résolutions angulaires et qui pourraient répondre à ces besoins scientifiques variés.Un modèle d'instrument répondant aux enjeux de météorologie de l'espace à ensuite été conçu avec une gamme en énergie allant jusqu'à 22 keV. Il possède une capacité duale de détection ions/électrons qui évite l'utilisation de capteurs différents pour la mesure des électrons et pour celle des ions. Destiné à être embarqué sur nanosatellite, il présente une masse de 1,8 kg et un diamètre de 19 cm. Un procédé de fabrication par impression 3D, et de fonctionnalisation du matériau imprimé a été défini et mis en œuvre. Un système de conversion ions/électrons utilisant des feuilles de carbone et permettant l'utilisation duale de cette caméra plasma a également été mis au point. Un instrument intégrant l'optique électrostatique et un système de détection dual simplifié a ensuite été testé sous faisceau d'électrons afin d'obtenir des réponses expérimentales précises en énergie et en angle. Les tests sous faisceau ont montré un comportement très proche de la simulation, renforçant ainsi la confiance dans la modélisation numérique. Le fonctionnement du système de conversion a été testé sous faisceau d'électrons et d'ions. L'une des perspectives à court terme de cette thèse est le développement, avec le soutien du CNES, d'un modèle complet de cette caméra plasma afin de rendre possible la démonstration en vol de cet instrument dédié à la météorologie de l'espace.Key phenomena governing the dynamics of space plasmas - including charged particle acceleration, magnetic reconnection and the turbulent dissipation of electromagnetic energy - are multi-scale in nature. In order to understand their role in the Sun-Earth relationship, whether in the solar wind, at the magnetopause or in the Earth's magnetosphere, it is essential to develop instrumentation that is both compact and high-performance, enabling the deployment of satellite constellations. However, the reference instruments used to measure the energy distribution of charged particles have a limited field of view. Adding electrostatic deflection systems circumvents this limitation, with the disadvantage of making these instruments heavier, slowing down their measurement rate, and therefore reducing their performance. In this case, more sensors are needed to achieve the desired performance, impacting satellite size and, ultimately, the number of satellites that can be deployed. The characterization of charged particle fluxes for studying space weather, conducted using compact instruments with a limited field of view, faces the same limitations.The first step in this research project was to develop a method for designing a new range of plasma spectrometers that overcome these limitations. These spectrometers are based on an innovative toroidal topology, offering an instantaneous hemispherical field of view that eliminates the need for electrostatic deflectors. Their planar detection system makes them true plasma cameras. The methods developed have enabled the numerical generation and characterization by simulating a wide range of plasma cameras with different angular resolutions that could meet these various scientific needs.A model instrument was then designed to meet the challenges of space weather applications, with an energy range of up to 22 keV. It features dual ion/electron detection capability, avoiding the need for separate sensors for electron and ion measurements. Intended for nanosatellites, it has a mass of 1.8 kg and a diameter of 19 cm. A 3D-printing manufacturing process and functionalization of the material have been defined and implemented. An ion/electron conversion system using carbon foils, enabling dual use of this plasma camera, has also been developed. An instrument integrating the electrostatic optics and a simplified dual detection system has been tested under an electron beam to obtain precise experimental responses in terms of energy and angle. The beam tests showed behavior very close to the simulation, reinforcing confidence in the numerical modeling. The principle of the conversion system was tested under electron and ion beams. One of the short-term prospects of this thesis is the development, with the support of CNES, of a complete model of this plasma camera, with the aim to demonstrate in orbit the performances of this instrument dedicated to space weather applications
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
Challenges of electron-scale measurements in the solar wind
No full textInternational audienceAcceleration processes in space plasmas are complex because they involve the interaction of particles with electromagnetic fields that may be distributed both in space and time. Understanding these processes in the solar wind requires high-time resolution observations at electron-scale. In this weakly magnetized medium, measuring both the energy spectrum and the 3D pitch-angle electron distribution at high-time resolution remains one of the main challenges of space plasma instrumentation. We both present the scientific challenges of these electron-scale measurements in the solar wind and recent advances in the development of high-time resolution electron spectrometers
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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