1,720,970 research outputs found
Commutative law for products of infinitely large isotropic random matrices
No full textEnsembles of isotropic random matrices are defined by the invariance of the probability measure under the left (and right) multiplication by an arbitrary unitary matrix. We show that the multiplication of large isotropic random matrices is spectrally commutative and self-averaging in the limit of infinite matrix size . The notion of spectral commutativity means that the eigenvalue density of a product ABC... of such matrices is independent of the order of matrix multiplication, for example, the matrix ABCD has the same eigenvalue density as ADCB. In turn, the notion of self-averaging means that the product of n independent but identically distributed random matrices, which we symbolically denote by AAA..., has the same eigenvalue density as the corresponding power of a single matrix drawn from the underlying matrix ensemble. For example, the eigenvalue density of ABCCABC is the same as that of . We also discuss the singular behavior of the eigenvalue and singular value densities of isotropic matrices and their products for small eigenvalues . We show that the singularities at the origin of the eigenvalue density and of the singular value density are in one-to-one correspondence in the limit : The eigenvalue density of an isotropic random matrix has a power-law singularity at the origin with a power when and only when the density of its singular values has a power-law singularity with a power = s/(4-s). hese results are obtained analytically in the limit . We supplement these results with numerical simulations for large but finite N and discuss finite-size effects for the most common ensembles of isotropic random matrices
Universality of random matrix dynamics
Full text linkWe discuss the concept of width-to-spacing ratio which plays the central role
in the description of local spectral statistics of evolution operators in
multiplicative and additive stochastic processes for random matrices. We show
that the local spectral properties are highly universal and depend on a single
parameter being the width-to-spacing ratio. We discuss duality between the
kernel for Dysonian Brownian motion and the kernel for the Lyapunov matrix for
the product of Ginibre matrices.Comment: 15 pages, 3 figure
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
Universal microscopic correlation functions for products of independent Ginibre matrices
No full textAkemann G, Burda Z. Universal microscopic correlation functions for products of independent Ginibre matrices. J. Phys. A: Math. Theor. 2012;45(46): 465201.We consider the product of n complex non-Hermitian, independent randommatrices, each of size NxN with independent identically distributed Gaussianentries (Ginibre matrices). The joint probability distribution of the complexeigenvalues of the product matrix is found to be given by a determinantal pointprocess as in the case of a single Ginibre matrix, but with a more complicatedweight given by a Meijer G-function depending on n. Using the method oforthogonal polynomials we compute all eigenvalue density correlation functionsexactly for finite N and fixed n. They are given by the determinant of thecorresponding kernel which we construct explicitly. In the large-N limit atfixed n we first determine the microscopic correlation functions in the bulkand at the edge of the spectrum. After unfolding they are identical to that ofthe Ginibre ensemble with n=1 and thus universal. In contrast the microscopiccorrelations we find at the origin differ for each n and generalise the knownBessel-law in the complex plane for n=2 to a new hypergeometric kernel 0_F_n-1
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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