1,720,962 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
Aspects dynamiques des structures projectives convexes
No full textIn this thesis we study the dynamics of the geodesic flow on convex projective manifolds, following work of Benoist, Bray, Crampon, Marquis and F.Zhu. These manifolds are quotients of properly convex, open, projective sets, equipped with the Hilbert metric, by discrete linear groups; the geodesic flow parametrises straight projective lines. These manifolds show similarities with non-positively curved Riemannian manifolds, hence we take inspiration from the literature on the geodesic flow of the latter, especially from work of Knieper and Roblin. In particular, most results presented here concern rank-one convex projective manifolds, which were introduced by M.Islam and A.Zimmer, and are analogues of rank-one Riemannian manifolds.Given a rank-one convex projective manifold, we introduce a flow-invariant closed subset of the unit tangent bundle, called the biproximal unit tangent bundle, which is proved to be the full unit tangent bundle if the manifold is compact, and on which the geodesic flow is proved to be topologically mixing in general. (A mixing result is also obtained in the higher-rank compact case.) We develop the theory of Patterson--Sullivan densities for rank-one convex projective manifolds, which is used to establish a Hopf--Tsuji--Sullivan--Roblin dichotomy and, if the convex core (introduced by Danciger--Guéritaud--Kassel) is compact, existence and uniqueness of the measure of maximal entropy on the biproximal unit tangent bundle. This theory also allows us to establish, under certain conditions, equidistribution results: closed geodesics equidistribute in the biproximal unit tangent bundle, while each orbit of the fundamental group in the universal cover accumulate on the projective boundary of the latter as prescribed by the Patterson--Sullivan density.We also study the critical exponent of convex projective manifolds, building on work of X.Nie and T.Zhang. More precisely, we look at the values taken by the critical exponent when letting the convex projective structure vary on a fixed topological manifold. For instance, we give the infimum of the critical exponents of certain families of convex projective structures, such as the family of finite-volume structures on a surface.Cette thèse est consacrée à l'étude de la dynamique du flot géodésique des variétés projectives convexes, et fait suite aux travaux de Benoist, Bray, Crampon, Marquis et F.Zhu sur le sujet.Ces variétés sont des quotients d'ouverts projectifs proprement convexes, munis de la métrique de Hilbert, par des groupes linéaires discrets sans torsion, et le flot géodésique y suit les lignes droites projectives.Elles présentent des similitudes avec les variétés riemanniennes à courbure négative ou nulle, ainsi on s'inspirera des nombreux travaux, notamment ceux de Knieper et Roblin, portant sur le flot géodésique de ces dernières. En particulier, la majeure partie des résultats présentés ici portent sur les variétés projectives convexes de rang un, introduites par M.Islam et A.Zimmer, et analogues aux variétés riemanniennes de rang un.Étant donnée une variété projective convexe de rang un, nous introduisons un fermé du fibré unitaire tangent invariant par le flot géodésique, appelé fibré unitaire tangent biproximal, dont nous montrons qu'il est le fibré unitaire tangent tout entier dans le cas compact, et que le flot géodésique y est topologiquement mélangeant en général. (Un résultat de mélange est aussi obtenu dans le cas compact de rang supérieur.) Nous développons la théorie des densités de Patterson--Sullivan pour les variétés projectives convexes de rang un, qui est utilisée pour obtenir une dichotomie de Hopf--Tsuji--Sullivan--Roblin et l'existence et unicité de la mesure d'entropie maximale sur le fibré unitaire tangent biproximal lorsque le cœur convexe (introduit par Danciger--Guéritaud--Kassel) est compact. Cette théorie nous permet aussi d'obtenir sous certaines conditions plusieurs résultats d'équidistribution : les géodésiques périodiques s'équidistribuent dans le fibré unitaire tangent biproximal, tandis que chaque orbite du groupe fondamental dans le revêtement universel de la variété s'accumule sur le bord projectif de ce dernier comme prescrit par la densité de Patterson--Sullivan.En parallèle, faisant suite aux travaux de X.Nie et T.Zhang, nous étudions l'exposant critique des variétés projectives convexes. Plus précisément, nous nous intéressons à l'ensemble des valeurs prises par l'exposant critique lorsque l'on fait varier la structure projective convexe sur une variété topologique fixée. Par exemple, nous déterminons la borne inférieure de l'exposant critique pour certaines familles de telles structures, comme l'ensemble des structures de volume fini sur une surface
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
Divisible convex sets with properly embedded cones
Full text linkIn this article we construct many examples of properly convex irreducible
domains divided by Zariski dense relatively hyperbolic groups in every
dimension at least 3. This answers a question of Benoist. Relative
hyperbolicity and non-strict convexity are captured by a family of properly
embedded cones (convex hulls of points and ellipsoids) in the domain. Our
construction is most flexible in dimension 3 where we give a purely topological
criterion for the existence of a large deformation space of geometrically
controlled convex projective structures with totally geodesic boundary on a
compact 3-manifold.Comment: 90 pages. Comments are welcome
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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