1,721,891 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
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
Study of Organic Field Effect Transistors : realization of ambipolar OFETs and study of injection mechanisms in vertical OFETs
No full textL'utilisation de Transistors à Effet de Champ Organiques (OFETs) est de plus en plus attractive grâce à la possibilité de production de composants plus légers, fabriqués à un moindre coût et sur des substrats flexibles. Le fait de pouvoir coupler une fonction émission de lumière à une fonction transistor rend son utilisation d'autant plus intéressante. C'est le cas des applications d'affichage, où les pixels sont réalisés par une technologie de matrice active à diodes électroluminescentes organiques (AMOLED). Le fait d'avoir un OFET électroluminescent permet de combiner un OFET avec une diode électroluminescente organique (OLED) et donc de simplifier la conception, les étapes de fabrication ainsi que d'augmenter la durée de vie des pixels. Durant cette thèse, l'étude et la fabrication des OFETs émetteurs de lumière ont été menés selon deux approches. La première est basée sur l'étude d'OFETs ambipolaires à base de N,N'-ditridecyl-3,4,9,10-perylenetetracarboxylic diimide (PTCDI-C13), un semi-conducteur de type-n, et de pentacène, un semi-conducteur de type-p, ce qui constitue une première étape à l'obtention d'OFET électroluminescent. La fabrication et la caractérisation de ces OFETs ambipolaires ont été réalisées pour la première fois dans l'équipe de recherche du laboratoire. Une étude de leur structure a été menée pour trouver les paramètres idéaux à l'obtention d'un transport de charges équilibré. La structure optimisée est une structure bicouche avec une épaisseur de pentacène de 8 nm et une épaisseur de PTCDI-C13 de 20 nm. L'ajout d'une couche émettrice entre les deux semi-conducteurs n'a pas permis d'obtenir une émission de lumière à cause du piégeage de charges trop important. Cependant, ce travail a ouvert de nouvelles perspectives pour les futurs travaux sur les OFETs ambipolaires. La deuxième approche pour étudier les OFETs émetteurs de lumière est plus innovante grâce au changement de la structure des transistors organiques classiques par une structure verticale. Cette structure présente l'avantage de pouvoir intégrer facilement une structure OLED et d'avoir une émission de lumière homogène sur une grande surface. Le principe de fonctionnement est totalement différent des OFETs classiques : ici, la modulation du courant ne se fait plus par un contrôle de la conductivité dans un canal semi-conducteur, mais par un contrôle de l'injection de charges au niveau de l'électrode source. L'étude de cette structure a permis d'obtenir des transistors organiques lumineux. Ensuite, l'étude des mécanismes d'injection de charges a permis de mieux comprendre le fonctionnement de ces transistors. Plusieurs matériaux ont été testés en tant qu'électrode source : l'or, l'argent, l'aluminium et l'ITO (Indium Tin Oxyde). Cela a permis de déterminer le mécanisme d'injection mis en jeu, soit l'injection de charges par la modulation de l'effet tunnel grâce à la courbure de bande induite par l'effet de grille dans la couche semi-conductrice proche de l'interface. Il a également été identifié que la qualité de l'interface électrode source/semi-conducteur joue un rôle majeur puisqu'une mauvaise qualité d'interface entraîne une diminution drastique des performances.Organic Field Effect Transistors (OFETs) is increasingly attractive thanks to the possibility of producing lighter components at lower cost and on flexible substrates. Being able to couple a light emission function to a transistor function makes its use more interesting. This is the case with display applications, where the pixels are produced by an active matrix technology of organic light-emitting diodes (AMOLED). Having a light-emitting OFET makes possible to combine an OFET with an organic light-emitting diode (OLED) and thus simplifying the design, the manufacturing steps as well as increasing the lifetime of pixels. During this thesis, the study and manufacture of light-emitting OFETs were carried out using two approaches. The first one is based on the study of ambipolar OFETs based on N, N'-ditridecyl-3,4,9,10-perylenetetracarboxylic diimide (PTCDI-C13), an n-type semiconductor, and pentacene, a p-type semiconductor. This study constitutes the first step in obtaining electroluminescent OFETs. The fabrication and characterization of these ambipolar OFETs were performed for the first time in the laboratory's research team. A study of their structure was carried out to find the ideal parameters to obtain a balanced charge transport. The optimized structure is a bilayer structure with a pentacene thickness of 8 nm and a PTCDI-C13 thickness of 20 nm. The addition of an emitting layer between the two semiconductors failed to achieve light emission due to excessive charges trapping. However, this study has opened up new perspectives for future work on ambipolar OFETs. The second approach to study light-emitting OFETs is more innovative thanks to the change of the structure from a classic planar structure to a vertical one. This structure has the advantage of being able to easily integrate an OLED structure and has a homogeneous light emission over a large area. The operating principle is totally different from conventional OFETs: here, the current modulation is no longer done by controlling the conductivity in a semiconductor channel, but by controlling the injection of charges at the source electrode. The study of this structure made it possible to obtain luminous organic transistors. Then, the study of charge injection mechanisms allowed us to understand more deeply the operating principe of these transistors. Several materials have been tested as the source electrode: gold, silver, aluminum and ITO (Indium Tin Oxide). This study allowed us to determine the injection mechanism involved, namely the injection of charges by the modulation of the tunnel effect thanks to the band bending induced by the gate effect in the semiconductor layer close to the interface. It has also been identified that the quality of the source electrode/semiconductor interface plays a major role since poor interface quality leads to a drastic decrease in performance
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
Optimization of UPS lighting systems based on DC low voltage bus
No full textLes diodes électroluminescentes (LEDs) constituent de nouvelles solutions pour créer des luminaires plus robustes, ayant un meilleur rendement de conversion et plus respectueuses de l'environnement. Malgré les avantages indiscutables déjà obtenus aujourd'hui, ce type de luminaire présente encore quelques optimisations possibles et offre des possibilités de fonctionnalités multiples. A travers plusieurs campagnes de tests, l'auteur montre sur des LEDs du commerce, que les points d'optimisation non encore exploités dans les luminaires commerciaux. Ces LEDs ont ainsi été testés sur de larges plages de fonctionnement du point de vue photométrique, électrique mais aussi thermique pour connaitre la reproductibilité des résultats obtenus. Ainsi les influences des conditions d'utilisation notamment en température de fonctionnement et niveaux de courant d'alimentation ont été étudiées. Pour dimensionner au mieux une alimentation électrique spécifique, une recherche de modèles de LED élémentaires a été effectuée. L'objectif est que les modèles tiennent compte des principaux paramètres mais soit suffisamment simple pour être inséré dans un environnement système afin de simuler le luminaire dans son environnement complet. Ainsi, l'étude comparative de plusieurs associations de LEDs a été effectuée permettant d'en déduire des compromis pour proposer de nouvelles solutions faibles consommatrices d'énergie à coût réduit incluant de nouveaux types d'alimentation.Light emitting diodes (LEDs) bring new possibilities to get luminaires more robust with an improved efficiency and more environmentally respectfull. Despite the benefits already achieved today, this type of luminaire still presents some possible optimizations and provides opportunities for multiple features. Through several tests, the author shows on LEDs in market that optimization points are not operated in commercial luminaires. These LEDs have been tested over a wide range of operation in photometric, electrical but also thermal to know the reproducibility of the results. Thus the influences of operating conditions including operating temperature and supply current levels were studied. To design a specific power supply for each LED type, a search of elementary LED models was performed. The objective is to take into account the main parameters of the models but also to be enough simple to be inserted into a system environment to simulate the luminaire in whole environment. Thus, the comparative study of several associations of LEDs was conducted to deduce the best compromise and propose new solutions to reduce energy consumptions and production costs, including new types of power supply
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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