1,720,998 research outputs found
On the existence of three closed magnetic geodesics for subcritical energies
No full textWe consider exact magnetic flows on closed orientable surfaces. We show that for almost every energy below Mañé’s critical value of the universal covering there are always at least three distinct closed magnetic geodesics with energy κ. If in addition the energy level is assumed to be non-degenerate we prove existence of infinitely many closed magnetic geodesics
Aplicações de Campos de Jacobi aos sistemas dinâmicos
Get PDFThis dissertation treat the study of Aplications of Jacobi Fields in the Dinamycal System,
following some works by [6], that use these fields to characterizae geodesic flows of Anosov
type. Then such apllications have been developed some concepts concerning Magnetic Flows
with the work of Gabriel P. Paternain e Keith Burns [2] and were finally developed for the
dynamic Billiards [14].Esta dissertação é dedicada ao estudo de Aplicações de Campos de Jacobi aos Sistemas
Dinâmicos, seguindo alguns trabalhos desenvolvidas por [6] que utilizam tais campos para caracterizar
fluxos geodésicos do tipo Anosov. Em seguida foram desenvolvidas alguns conceitos
envolvendo Fluxo Magnético com o trabalho de Gabriel P. Paternain e Keith Burns [2] e por
último foram desenvolvidos aplicações de tais campos para a dinâmica do Bilhar [14].CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superio
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
The longitudinal KAM-cocycle of a magnetic flow
No full textAbstract. Let M be a closed oriented surface of negative Gaussian curvature and let Ω be a non-exact 2-form. Let λ be a small positive real number. We show that the longitudinal KAM-cocycle of the magnetic flow given by λΩ is a coboundary if and only if the Gaussian curvature is constant and Ω is a constant multiple of the area form. 1
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
- …
