1,720,956 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
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
Extension de l'homomorphisme de Calabi aux cobordismes lagrangiens
No full textCe mémoire traite de la construction d’un nouvel invariant des cobordismes lagrangiens. Cette construction est inspirée des travaux récents de Solomon dans lesquels une extension de l’homomorphisme de Calabi aux chemins lagrangiens exacts est donnée. Cette extension fut entre autres motivée par le fait que le graphe d’une isotopie hamiltonienne est un chemin lagrangien exact. Nous utilisons la suspension lagrangienne, qui associe à chaque chemin lagrangien exact un cobordisme lagrangien, pour étendre la construction de Solomon aux cobordismes lagrangiens. Au premier chapitre nous donnons une brève exposition des propriétés élémentaires des variétés symplectiques et des sous-variétés lagrangiennes. Le second chapitre traite du groupe des difféomorphismes hamiltoniens et des propriétés fondamentales de l’homomorphisme de Calabi. Le chapitre 3 est dédié aux chemins lagrangiens, l’invariant de Solomon et ses points critiques. Au dernier chapitre nous introduisons la notion de cobordisme lagrangien et construisons le nouvel invariant pour finalement analyser ses points critiques et l’évaluer sur la trace de la chirurgie de deux courbes sur le tore. Dans le cadre de ce calcul, nous serons en mesure de borner la valeur du nouvel invariant en fonction de l’ombre du cobordisme, une notion récemment introduite par Cornea et Shelukhin.In this master's thesis, we construct a new invariant of Lagrangian cobordisms. This construction is inspired by the recent works of Solomon in which an extension of the Calabi homomorphism to exact Lagrangian paths is given. Solomon's extension was motivated by the fact that the graph of any Hamiltonian isotopy is an exact Lagrangian path. We use the Lagrangian suspension construction, which associates to every exact Lagrangian path a Lagrangian cobordism, to extend Solomon's invariant to Lagrangian cobordisms. In the first chapter, we give a brief introduction to the elementary properties of symplectic manifolds and their Lagrangian submanifolds. In the second chapter, we present an introduction to the group of Hamiltonian diffeomorphisms and discuss the fundamental properties of the Calabi homomorphism. Chapter 3 is dedicated to Lagrangian paths, Solomon's invariant and its critical points. In the last chapter, we introduce the notion of Lagrangian cobordism and we construct the new invariant. We analyze its critical points and evaluate it on the trace of the Lagrangian surgery of two curves on the torus. In this setting we further bound the new invariant in terms of the shadow of the cobordism, a notion recently introduced by Cornea and Shelukhin
Diamètre spectral et cohomologie symplectique
Get PDFLe groupe de difféomorphismes hamiltoniens à support compact d’une variété
symplectique admet une distance naturelle bi-invariante, d’après les
travaux de Viterbo, Schwarz, Oh, Frauenfelder et Schlenk, construite à partir
des invariants spectraux en homologie de Floer Hamiltonienne. Cette
distance, appelée la norme spectrale, s’est révélée être un outil fort utile en
topologie symplectique. Par contre, son diamètre reste inconnu en général.
En fait, pour les variétés symplectiques fermées, il n’existe même pas de
critère pour déterminer si la norme spectrale a un diamètre fini ou infini.
Il a été conjecturé que, pour les variétés symplectiquement asphériques, le
diamètre de la norme spectrale est infini.
Dans cette thèse, nous démontrons que pour tout domaine de Liouville, la
norme spectrale a un diamètre infini si et seulement si la cohomologie symplectique
du domaine de Liouville en question est non nulle. Ceci généralise
un résultat de Monzner-Vichery-Zapolsky et admet plusieurs applications
dans le cadre des variétés symplectiques fermées. En particulier, nous démontrons
que le produit de deux variétés symplectiquement asphériques a
un diamètre spectral infini. Plus généralement, nous démontrons que toute
variété symplectiquement asphérique contenant un domaine de Liouville incompressible
de codimension zéro avec cohomologie symplectique non nulle
doit avoir un diamètre spectral infini.The group of compactly supported Hamiltonian diffeomorphisms of a symplectic
manifold is endowed with a natural bi-invariant distance, due to
Viterbo, Schwarz, Oh, Frauenfelder and Schlenk, coming from spectral invariants
in Hamiltonian Floer homology. This distance, called the spectral
norm, has found numerous applications in symplectic topology. However,
its diameter is still unknown in general. In fact, for closed symplectic manifolds
there is no unifying criterion for the diameter to be finite or infinite.
It has been conjectured that for closed symplectically aspherical manifolds,
the spectral norm has infinite diameter.
In this thesis, we prove that for any Liouville domain the spectral norm has
infinite diameter if and only if its symplectic cohomology does not vanish.
This generalizes a result of Monzner-Vichery-Zapolsky and has applications
in the setting of closed symplectic manifolds. For instance, we show that the
product of two closed symplectically aspherical manifold has an infinite spectral
diameter . More generally, we prove that any symplectically aspherical
manifold which contains an incompressible Liouville domain of codimension
zero with non-vanishing symplectic cohomology must have infinite spectral
diameter
The spectral diameter of a Liouville domain
Get PDFThe group of compactly supported Hamiltonian diffeomorphisms of a symplectic manifold is endowed with a natural bi-invariant distance, due to Viterbo, Schwarz, Oh, Frauenfelder and Schlenk, coming from spectral invariants in Hamiltonian Floer homology. This distance has found numerous applications in symplectic topology. However, its diameter is still unknown in general. In fact, for closed symplectic manifolds there is no unifying criterion for the diameter to be infinite. In this paper, we prove that for any Liouville domain this diameter is infinite if and only if its symplectic cohomology does not vanish. This generalizes a result of Monzner-Vichery-Zapolsky and has applications in the setting of closed symplectic manifolds.47 pages, 13 figures. Improved the introductio
Extension de l'homomorphisme de Calabi aux cobordismes lagrangiens
Get PDFCe mémoire traite de la construction d’un nouvel invariant des cobordismes lagrangiens. Cette construction est inspirée des travaux récents de Solomon dans lesquels une extension de l’homomorphisme de Calabi aux chemins lagrangiens exacts est donnée. Cette extension fut entre autres motivée par le fait que le graphe d’une isotopie hamiltonienne est un chemin lagrangien exact. Nous utilisons la suspension lagrangienne, qui associe à chaque chemin lagrangien exact un cobordisme lagrangien, pour étendre la construction de Solomon aux cobordismes lagrangiens. Au premier chapitre nous donnons une brève exposition des propriétés élémentaires des variétés symplectiques et des sous-variétés lagrangiennes. Le second chapitre traite du groupe des difféomorphismes hamiltoniens et des propriétés fondamentales de l’homomorphisme de Calabi. Le chapitre 3 est dédié aux chemins lagrangiens, l’invariant de Solomon et ses points critiques. Au dernier chapitre nous introduisons la notion de cobordisme lagrangien et construisons le nouvel invariant pour finalement analyser ses points critiques et l’évaluer sur la trace de la chirurgie de deux courbes sur le tore. Dans le cadre de ce calcul, nous serons en mesure de borner la valeur du nouvel invariant en fonction de l’ombre du cobordisme, une notion récemment introduite par Cornea et Shelukhin.In this master's thesis, we construct a new invariant of Lagrangian cobordisms. This construction is inspired by the recent works of Solomon in which an extension of the Calabi homomorphism to exact Lagrangian paths is given. Solomon's extension was motivated by the fact that the graph of any Hamiltonian isotopy is an exact Lagrangian path. We use the Lagrangian suspension construction, which associates to every exact Lagrangian path a Lagrangian cobordism, to extend Solomon's invariant to Lagrangian cobordisms. In the first chapter, we give a brief introduction to the elementary properties of symplectic manifolds and their Lagrangian submanifolds. In the second chapter, we present an introduction to the group of Hamiltonian diffeomorphisms and discuss the fundamental properties of the Calabi homomorphism. Chapter 3 is dedicated to Lagrangian paths, Solomon's invariant and its critical points. In the last chapter, we introduce the notion of Lagrangian cobordism and we construct the new invariant. We analyze its critical points and evaluate it on the trace of the Lagrangian surgery of two curves on the torus. In this setting we further bound the new invariant in terms of the shadow of the cobordism, a notion recently introduced by Cornea and Shelukhin
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
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