1,720,968 research outputs found
Hydrodynamic-type systems describing 2-dimensional polynomially integrable geodesic flows
No full textBi-Hamiltonian structure of the Oriented Associativity equation
No full textThe Oriented Associativity equation plays a fundamental role in
the theory of Integrable Systems. In this paper we prove that the equa-
tion, besides being Hamiltonian with respect to a first-order Hamilto-
nian operator, has a third-order non-local homogeneous Hamiltonian
operator belonging to a class which has been recently studied, thus
providing a highly non-trivial example in that class and showing in-
triguing connections with algebraic geometry
Towards the classification of homogeneous third-order Hamiltonian operators
Get PDFLet be a vector space of dimension . We demonstrate that
-component third-order Hamiltonian operators of differential-geometric
type are parametrised by the algebraic variety of elements of rank in
that lie in the kernel of the natural map
. Non-equivalent operators correspond to
different orbits of the natural action of . Based on this result,
we obtain a classification of such operators for
Systems of conservation laws with third-order Hamiltonian structures
Get PDFWe investigate -component systems of conservation laws that possess
third-order Hamiltonian structures of differential-geometric type.
% Examples include equations of associativity of two-dimensional topological
% field theory (WDVV equations). and various equations of Monge-Amp`ere
% type.
The classification of such systems is reduced to the projective
classification of linear congruences of lines in
satisfying additional geometric constraints. Algebraically, the problem can
be reformulated as follows: for a vector space of dimension ,
classify -tuples of skew-symmetric 2-forms such
that
for some non-degenerate symmetric
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
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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