1,721,017 research outputs found
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
Enhanced Lieb-Robinson bounds for a class of Bose-Hubbard type Hamiltonians
Full text linkSeveral recent works have considered Lieb-Robinson bounds (LRBs) for
Bose-Hubbard-type Hamiltonians. For certain special classes of initial states
(e.g., states with particle-free regions or perturbations of stationary
states), the velocity of information propagation was bounded by a constant in
time, , similarly to quantum spin systems. However, for the more
general class of bounded-density initial states, the first-named author
together with Vu and Saito derived the velocity bound , where
is the spatial lattice dimension. For , this bound allows for
accelerated information propagation. It has been known since the work of Eisert
and Gross that some systems of lattice bosons are capable of accelerated
information propagation. It is therefore a central question to understand under
what conditions the bound can be enhanced. Here, we prove
that additional physical constraints, translation-invariance and a -body
repulsion of the form with , lead to a LRB with for any initial state of bounded energy density. We also
identify examples of quantum states which show that no further enhancement is
possible without using additional dynamical constraints.Comment: 41 pages, 2 figure
On the finite-size Lyapunov exponent for the Schröedinger operator with skew-shift potential
No full textIt is known that a one-dimensional quantum particle is localized when subjected to an arbitrarily weak random potential. It is conjectured that localization also occurs for an arbitrarily weak potential generated from the nonlinear skew-shift dynamics: with an irrational number. Recently, Han, Schlag, and the second author derived a finite-size criterion in the case when is the golden mean, which allows to derive the positivity of the infinite-volume Lyapunov exponent from three conditions imposed at a fixed, finite scale. Here we numerically verify the two conditions among these that are amenable to computer calculations.CAM
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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Universality of Lévy Matrices
No full textMotivated by conjectures from physics, we study the eigenvalues and eigenvectors of Lévy matrices, which are symmetric random matrices whose upper triangular entries are independent, identically distributed α-stable distributions. For α < 2, these distributions are heavy-tailed, with infinite second moment. For α ∈ (1, 2), we show that at all finite non- zero energies, Lévy matrices exhibit completely delocalized eigenvectors and local eigenvalue statistics that asymptotically match those of the Gaussian Orthogonal Ensemble. For almost all α ∈ (0, 2), we prove the same result for small energies, including zero. Additionally, for almost all α ∈ (0, 2), we analyze the statistics of eigenvector entries of Lévy matrices at small energies and show that the limiting distribution of any such entry is non-Gaussian. For entries of the eigenvector corresponding to the median eigenvalue, we identify this distribution explicitly. We also demonstrate the presence of non-trivial correlations between eigenvector entries corresponding to nearby eigenvalues. These findings contrast sharply with the known eigenvector behavior for other random matrix ensembles. Further, our results for both eigenvalues and eigenvectors generalize to a large class of heavy-tailed random matrices.Mathematic
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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