1,720,970 research outputs found
Une étude du comportement des noyaux de groupes discrets
No full textCette thèse traite de noyaux (fonction de deux variables à valeur réelles) sur les groupes discrets de type fini. Différentes formes faibles de moyennabilité y sont étudiées, dont notamment la propriété A, la proprieté de Haagerup et l'uniforme plongeabilité dans un espace de Hilbert. Parmi les résultats principaux de cette thèse, l'auteur donne des formules explicites pour ces noyaux dans de nombreuses situations dont les extensions de groupes et les groupes agissant convenablement sur un espace métrique ayant la propriété A. Par ailleurs, en utilisant la notion de noyau de type positif, l'auteur relie les notions de compression hilbertienne et de rotondité généralisée via une inégalité lui permettant d'obtenir les premiers exemples de calculs explicites de rotondité généralisée, à savoir celle des groupes libres et des groupes abéliens libres
Création d’un projet bi-disciplinaire d’analyse de données enastrophysique pour les élèves du Gymnase
No full textBased on simulated raw data from an international gamma-ray telescope experiment (CTA), in which the University of Geneva participates, a data analysis project in Python tailored to the level of high school students has been developed. This project is part of an interdisciplinary learning approach that combines physics and computer science and is intended to be completed over the course of one week. By using their prior knowledge in computer science and physics, this novel pedagogical sequence aims at immersing students in the world of scientific research, focusing on an authentic and meaningful topic.
This document presents the project, exploring programming aspects from the students’ perspective and simplifying the complex environment originally designed for physicists. Additionally, an analysis of pedagogical choices and the underlying didactic justifications is conducted. This activity has been suc- cessfully tested with a group of 47 students; an analysis of the results from a didactic standpoint is performed, sharing the work done by the students as well as their daily comments and feedback, all re- corded on Moodle. Finally, based on these observations, possibilities for future improvement are detailed.</p
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
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
On spectra of simple random walks on one-relator groups
No full textFor a one relator group Gamma = [X : r], we study the spectra of the transition operators h(X) and h(S) associated with the simple random walks on the directed Cayley graph and ordinary Cayley graph of Gamma respectively. We show that, generically (in the sense of Gromov), the spectral radius of h(X) is (#X)(-1/2) (which implies that the semi-group generated by X is free). We give upper bounds on the spectral radii of h(X) and h(S). Finally, for Gamma the fundamental group of a closed Riemann surface of genus g greater than or equal to 2 in its standard presentation, we show that the spectrum of h(S) is an interval [-r, r], with r less than or equal to g(-1)(2g - 1)(1/2). Techniques are operator-theoretic
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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