1,721,008 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
Global Solutions for the gravity water waves system: Infinite depth setting and flat bottom setting
No full textIn this thesis, we study the gravity water waves system in two settings: (i) the water region is two dimensional and there is no bottom, (ii) the water region is three dimensional and the bottom of the water region is flat.
For the gravity water waves system in the infinite depth setting, we prove the global existence and the modified scattering for a class of initial data, which can have infinite energy. The initial data is only required to be small above the level . No assumption is assumed below this level. As a direct consequence, the momentum condition assumed on the physical velocity in all previous small energy results by Ionescu-Pusateri\cite{IP1}, Alazard-Delort\cite{alazard} and Ifrim-Tataru \cite{tataru3} is removed.
For the gravity water waves system in the flat bottom setting, we prove global existence for suitably small initial data and non-existence of traveling waves below a certain level of smallness, which strongly contrasts the behavior of the solution of the same system in the case
Long term regularity of some periodic nonlinear dispersive equations
No full textThis thesis considers two periodic nonlinear dispersive equations arising from the study of fluid mechanics: (i) the 2D one-fluid Euler--Poisson system and (ii) the 3D gravity water wave system.
The one-fluid Euler--Poisson system is a basic plasma physics model, in which a compressible electron fluid flows under its own electrostatic field. The first part of the thesis concerns its periodic solutions, namely those living on the square torus. We prove long-term regularity of periodic solutions of this system in 2 spatial dimensions with small data. Our main conclusion is that on a square torus of side length , if the initial data is sufficiently close to a constant solution, then the solution is wellposed for a time at least , where is the size of the initial data.
The gravity water wave system describes the motion of an incompressible fluid delineated from above by an interface, for exanple, the water in the ocean. The second part of the thesis studies its solutions periodic in the two horizontal directions, which describe a column of water whose base is a 2D torus. We also prove long-term regularity of periodic solutions of this system with small data.
Our main conclusion is that on a square torus of side length , if the initial data is sufficiently close to a constant solution,
then the solution is wellposed for a time at least , where is the size of the initial data
Long term regularity of some periodic nonlinear dispersive equations
No full textThis thesis considers two periodic nonlinear dispersive equations arising from the study of fluid mechanics: (i) the 2D one-fluid Euler--Poisson system and (ii) the 3D gravity water wave system.
The one-fluid Euler--Poisson system is a basic plasma physics model, in which a compressible electron fluid flows under its own electrostatic field. The first part of the thesis concerns its periodic solutions, namely those living on the square torus. We prove long-term regularity of periodic solutions of this system in 2 spatial dimensions with small data. Our main conclusion is that on a square torus of side length , if the initial data is sufficiently close to a constant solution, then the solution is wellposed for a time at least , where is the size of the initial data.
The gravity water wave system describes the motion of an incompressible fluid delineated from above by an interface, for exanple, the water in the ocean. The second part of the thesis studies its solutions periodic in the two horizontal directions, which describe a column of water whose base is a 2D torus. We also prove long-term regularity of periodic solutions of this system with small data.
Our main conclusion is that on a square torus of side length , if the initial data is sufficiently close to a constant solution,
then the solution is wellposed for a time at least , where is the size of the initial data
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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