1,720,969 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
Modified double brackets and a conjecture of S. Arthamonov
No full textAround 20 years ago, M. Van den Bergh introduced double Poisson brackets asoperations on associative algebras inducing Poisson brackets under therepresentation functor. Weaker versions of these operations, called modifieddouble Poisson brackets, were later introduced by S. Arthamonov in order toinduce a Poisson bracket on moduli spaces of representations of thecorresponding associative algebras. Moreover, he defined two operations that heconjectured to be modified double Poisson brackets. The first case of thisconjecture was recently proved by M. Goncharov and V. Gubarev motivated by thetheory of Rota-Baxter operators of nonzero weight. We settle the conjecture byrealising the second case as part of a new family of modified double Poissonbrackets. These are obtained from mixed double Poisson algebras, a new class ofalgebraic structures that are introduced and studied in the present work.Comment: v4: Journal versio
Multiplicative quiver varieties and integrable particle systems
Full text linkThe main goal of this thesis is to provide a systematic study of several integrable systems defined on complex Poisson manifolds associated to extended cyclic quivers. These spaces are particular examples of multiplicative quiver varieties of Crawley-Boevey and Shaw, for which Van den Bergh observed that they can be equipped with a Poisson bracket obtained by quasi-Hamiltonian reduction. In his approach, Van den Bergh introduced the notion of double brackets to translate the geometric quasi-Hamiltonian structure associated to these varieties directly at the level of the path algebra of the quivers. We pursue this line of thought and examine these double brackets in order to find families of algebraic elements on the path algebra of extended cyclic quivers that give rise to families of Poisson commuting functions on the corresponding multiplicative quiver varieties. This provides a way to obtain candidates for Liouville integrability, and this can be adapted to the case of degenerate integrability. For specific dimensions of these spaces, we can compute the number of functionally independent elements in each family, and conclude that we can form integrable systems. They can be written in terms of local coordinates, and be related to the trigonometric spin Ruijsenaars-Schneider system or generalisations of the latter system. As part of our construction, we also prove that their flows can be obtained by the projection method from explicit integrations performed before the quasi-Hamiltonian reduction. Another application of this work consists in describing the Poisson structure in terms of local coordinates. In particular, this allows us to prove a conjecture of Arutyunov and Frolov regarding the form of the Poisson bracket for the trigonometric spin Ruijsenaars-Schneider system
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
Morphisms of double (quasi-)Poisson algebras and action-angle duality of integrable systems
Full text linkDouble (quasi-)Poisson algebras were introduced by Van den Bergh as non-commutative analogues of algebras endowed with a (quasi-)Poisson bracket. In this work, we provide a study of morphisms of double (quasi-)Poisson algebras, which we relate to the H0-Poisson structures of Crawley-Boevey. We prove in particular that the double (quasi-)Poisson algebra structure defined by Van den Bergh for an arbitrary quiver only depends upon the quiver seen as an undirected graph, up to isomorphism. We derive from our results a representation theoretic description of action-angle duality for several classical integrable systems
Spin versions of the complex trigonometric Ruijsenaars-Schneider model from cyclic quivers
Full text linkWe study multiplicative quiver varieties associated to specific extensions of cyclic quivers with vertices. Their global Poisson structure is characterised by quasi-Hamiltonian algebras related to these quivers, which were studied by Van den Bergh for an arbitrary quiver. We show that the spaces are generically isomorphic to the case corresponding to an extended Jordan quiver. This provides a set of local coordinates, which we use to interpret integrable systems as spin variants of the trigonometric Ruijsenaars-Schneider system. This generalises to new spin cases recent works on classical integrable systems in the Ruijsenaars-Schneider family
Double quasi-Poisson brackets: fusion and new examples
Full text linkWe exhibit new examples of double quasi-Poisson brackets, based on some classification results and the method of fusion. This method was introduced by Van den Bergh for a large class of double quasi-Poisson brackets which are said differential, and our main result is that it can be extended to arbitrary double quasi-Poisson brackets. We also provide an alternative construction for the double quasi-Poisson brackets of Van den Bergh associated to quivers, and of Massuyeau-Turaev associated to the fundamental groups of surfaces
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
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