1,721,096 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
Gauged supergravities in various spacetime dimensions
No full textIn this review articel we study the gaugings of extended supergravity theories in various space-time dimensions. These theories describe the low-energy limit of non-trivial string compactifications. For each theory under consideration we review all possible gaugings that are compatible with supersymmetry. They are parameterized by the so-called embedding tensor which is a group theoretical object that has to satisfy certain representation constraints. This embedding tensor determines all couplings in the gauged theory that are necessary to preserve gauge invariance and supersymmetry. The concept of the embedding tensor and the general structure of the gauged supergravities are explained in detail. The methods are then applied to the half-maximal (N=4) supergravities in d=4 and d=5 and to the maximal supergravities in d=2 and d=7. Examples of particular gaugings are given. Whenever possible, the higher-dimensional origin of these theories is identified and it is shown how the compactification parameters like fluxes and torsion are contained in the embedding tensor
Type II supergravity origin of dyonic gaugings
Full text linkDyonic gaugings of four-dimensional supergravity typically exhibit a richer vacuum structure compared to their purely electric counterparts, but their higher-dimensional origin often remains more mysterious. We consider a class of dyonic gaugings with gauge groups of the type (SO(p, q) x SO (p', q')) proportional to N with N nilpotent. Using generalized Scherk-Schwarz reductions of exceptional field theory, we show how these four-dimensional gaugings may be consistently embedded in type II supergravity upon compactification around products of spheres and hyperboloids. As an application, we give the explicit uplift of the N = 4 AdS(4) vacuum of the theory with gauge group (SO(6) x SO (1, 1)) proportional to T(12)into a supersymmetric AdS(4) x M-5 x S-1 S-fold solution of IIB supergravity. The internal space M-5 is a squashed S-5 preserving an SO(4) subset of SO(6) subset of its isometries
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
Supergravity : AdS3 vacua and higher-derivative corrections
No full textLa supergravité est l’extension supersymétrique de la relativité générale. Elle est notamment essentielle à l’étude de la théorie des cordes, un des candidats prometteurs à l’unification des forces fondamentales. Cette dernière présente des dualités, c’est-à-dire des symétries reliant des solutions a priori différentes, et prédit des corrections en dérivées d’ordre supérieur à la relativité générale. La première partie de cette thèse est dédiée à l’étude conjointe de ces corrections et des dualités, grâce aux outils de la supergravité. Il est montré que la préservation des symétries de dualité, en présence de corrections en dérivées d’ordre quatre, nécessite la déformation des transformations de dualité. Une fois ces déformations identifiées, l’action corrigée est écrite de manière à rendre explicite la dualité. La supergravité est également fondamentale à la correspondance AdS/CFT, qui conjecture l’équivalence entre certaines théories conformes des champs en dimension d et des supergravités en espace-temps anti-de Sitter de dimension d + 1. La correspondance AdS3 /CFT2 est particulièrement prometteuse, grâce à la bonne connaissance des théories conformes à deux dimensions. Nous proposons dans la seconde partie de cette thèse une classification des solutions anti-de Sitter à trois dimensions, préservant en particulier des supersymétries chirales. Nous développons ensuite une méthode de calcul des spectres Kaluza-Klein autour de ces vides, grâce aux techniques des théories exceptionnelles des champs. Cette méthode permet de contourner l’analyse harmonique standard et donne accès à des vides préservant peu, ou pas, de supersymétries.Supergravity is the supersymmetric extension of general relativity. It is essential for the study of string theory, one of the promising candidates for the unification of fundamental forces. The latter presents dualities, i.e. symmetries linking a priori different solutions, and predicts corrections in higher order derivatives to general relativity. The first part of this thesis is dedicated to the joint study of these corrections and dualities, using the tools of supergravity. It is shown that the preservation of duality symmetries, in the presence of fourth order derivative corrections, requires the deformation of the duality transformations. Once these deformations are identified, the corrected action is written in such a way as to make the duality explicit.Supergravity is also fundamental to the AdS/CFT correspondence, which conjectures the equivalence between certain conformal field theories in d dimensions and supergravity in anti-de Sitter spacetime of dimension d + 1. The AdS3 /CFT2 correspondence is particularly promising, thanks to the good knowledge of two-dimensional conformal theories. In the second part of this thesis, we propose a classification of three-dimensional anti-de Sitter solutions, preserving in particular chiral supersymmetries. We then develop a method to compute Kaluza-Klein spectra around these vacua, using techniques from exceptional field theories. This method allows to bypass the standard harmonic analysis and gives access to vacua preserving few, or no, supersymmetries
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
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