1,720,958 research outputs found
Un risultato di densità in uno spazio di tipo BV in gruppi di Carnot
Full text linkIn the setting of Carnot groups (connected, simply connected and stratified Lie groups), we prove a density result for a BV-type space previously introduced in [3]. In addition, we relate the dual of this BV-type space with the dual of the well known space of functions of intrinsic bounded variation. These results extend to the setting of Carnot groups some properties studied by Phuc e Torres in [22] and [23] in the Euclidean setting.Si prova un risultato di densità per uno spazio di tipo BV nell'ambito dei gruppi di Carnot (gruppi di Lie connessi, semplicemente connessi e stratificati) già introdotto in [3]. Come conseguenza di questo risultato di densità si mettono in relazione lo spazio delle funzioni a variazione (intrinseca) limitata con il duale di questo spazio. Questi risultati estendono al caso dei gruppi di Carnot alcune proprietà studiate in ambito euclideo da Phuc e Torres in [22] and [23]
An integral formula on the Heisenberg group
Full text linkLet H^n denote the (2n+1)-dimensional (sub-Riemannian) Heisenberg group. In this note, we shall prove an integral identity (see Theorem 1.2) that generalizes a formula obtained in the Seventies by Reilly (Indiana Univ Math J 26(3):459–472, 1977). Some first applications will be given in Sect. 4
Geometric inequalities in Carnot groups
No full textLet G be a sub-Riemannian k-step Carnot group of homogeneous dimension Q. In this paper, we shall prove
several geometric inequalities concerning smooth hypersurfaces (i.e. codimension one submanifolds) immersed in
G, endowed with the H-perimeter measure
Stable H-Minimal Hypersurfaces
Full text linkWe prove some stability results for smooth non-characteristic
H-minimal hypersurfaces immersed in a sub-Riemannian k-step Carnot group
G. The main tools are the formulas for the first and second variation of the
H-perimeter measure together with some non-trivial geometric identities
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
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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