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
Intra-unit-cell magnetic order in cuprate high temperature superconductors
No full textCette thèse a pour motivation l'étude de l'ordre magnétique à q=0 dans les cuprates supraconducteurs à haute température critique. Cet ordre a déjà été reporté dans quatre familles de cuprates grâce à la diffusion de neutrons polarisés. Il est établi, sur une large gamme de dopage en trous, que cet ordre se développe à partir d'une température Tmag comparable à la température d'apparition de la phase de pseudo-gap T*. Ces observations sont compatibles avec un modèle de boucles de courant, qui induisent des moments magnétiques orbitaux. Les symétries mises en jeu sont la brisure par renversement du temps et l'invariance par translation. D'un point de vue expérimental, il s'agit non seulement de vérifier systématiquement l'existence de cet ordre magnétique, mais également de saisir sa nature. Nous nous sommes particulièrement intéressés à l'étude de deux systèmes bicouches, YBa2Cu3O6+x et Bi2Sr2CaCu2O8+x. Dans un premier temps, nous avons montré la persistance de l'ordre magnétique à q=0 pour une valeur de Tmag relativement élevée, dans des échantillons proches du dopage optimal. Toutefois, l'intensité magnétique associée est fortement réduite. Nous avons montré que ceci était en fait dû à la présence de domaines de taille finie, l'ordre est à courte portée. Aussi, nous avons déterminé le facteur de structure le long de l'axe c, il présente une décroissance rapide unique. Dans le cadre des boucles de courant, une possible modélisation consisterait en une résultante de deux anapoles pointant le long de b* au sein de la bicouche. D'autre part, nous avons confirmé l'existence d'un moment magnétique incliné sous Tmag. Nous avons cependant mis en évidence un caractère Ising le long de l'axe c à haute température. Enfin, nous avons prouvé que le signal associé à l'ordre magnétique à q=0 continue d'augmenter dans l'état supraconducteur.This work is motivated by the study of the intra-unit-cell magnetic order in cuprate high temperature superconductors. It has been already reported in four cuprate families by using polarized neutron scattering, and it is well documented in a wide hole doping range. This order develops below Tmag, which matches the pseudo-gap temperature T*. This magnetic phase could be induced by the staggered orbital magnetism within the unit cell as proposed in the loop current model. This intra-unit-cell magnetic order indicates that time reversal symmetry is broken, but translation invariance is preserved. Experimentally, the goal is not only to systematically verify the existence of this intra-unit-cell magnetic order, but also to seize its nature. We particularly focused on two bilayer systems, YBa2Cu3O6+x and Bi2Sr2CaCu2O8+x. First, we revealed the persistence of the intra-unit-cell magnetic order at relatively high Tmag, near optimal doping. Compared to samples with a lower hole doping level, the magnetic intensity is strongly reduced. We demonstrated that this is due to finite magnetic correlation lengths. Moreover, we determined the associated magnetic structure factor along c, which displays a unique sharp decreasing. It is consistent with a model in which the sum of two anapoles within the bilayer is pointing along b*. Besides, below Tmag, we confirmed the existence of a tilt of the magnetic moment. However, we showed that at high temperature an Ising-like response along the c-axis is recovered. Finally, we proved that the magnetic signal associated to the intra-unit-cell magnetic order is still increasing in the superconducting state
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
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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