1,720,955 research outputs found
Spectrum of a singularly perturbed periodic thin waveguide
No full textWe consider a family {Omega(epsilon)}epsilon>o of periodic domains in R-2 with waveguide geometry and analyse spectral properties of the Neumann Laplacian -Delta(Omega)epsilon on Omega(epsilon). The waveguide Omega(epsilon) is a union of a thin straight strip of the width e and a family of small protuberances with the so-called "room-and-passage" geometry. The protuberances are attached periodically, with a period epsilon, along the strip upper boundary. We prove a (kind of) resolvent convergence of -Delta(Omega epsilon) to a certain operator on the line as epsilon -> 0. Also we demonstrate Hausdorff convergence of the spectrum. In particular, we conclude that if the sizes of "passages" are appropriately scaled the first spectral gap of -Delta(Omega epsilon). is determined exclusively by geometric properties of the protuberances. The proofs are carried out using methods of homogenization theory. (C) 2017 Elsevier Inc. All rights reserved
Neumann spectral problem in a domain with very corrugated boundary
No full textLet Omega subset of R-n be a bounded domain. We perturb it to a domain Omega(epsilon) attaching a family of small protuberances with "room-and-passage"-like geometry (epsilon > 0 is a small parameter). Peculiar spectral properties of Neumann problems in so perturbed domains were observed for the first time by R. Courant and D. Hilbert. We study the case, when the number of protuberances tends to infinity as epsilon > 0 and they are E-periodically distributed along a part of partial derivative Omega. Our goal is to describe the behavior of the spectrum of the operator A(epsilon) = -(rho(epsilon))(-l) Delta(epsilon)(Omega), where Delta(epsilon)(Omega) is the Neumann Laplacian in Omega(epsilon), and the positive function rho(epsilon) is equal to 1 in Omega. We prove that the spectrum of A(epsilon) converges as epsilon -> 0 to the "spectrum" of a certain boundary value problem for the Neumann Laplacian in Omega with boundary conditions containing the spectral parameter in a nonlinear manner. Its eigenvalues may accumulate to a finite point. (C) 2015 Elsevier Inc. All rights reserved. ZB 0 Z8 0 ZR 0 ZS
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
On the Spectrum of Riemannian Manifolds with Attached Thin Handles
No full textThe behavior as ε → 0 of the spectrum of the Laplace Beltrami operator Δε is studied on Rieinannian manifolds depending on a small parameter ε . They consist of a fixed compact manifold with attached handles whose radii tend to zero as ε → 0. We consider two cases: when the number of the handles is fixed and their lengthes are also fixed and when the number of the handles tend to infinity and their lengthes tend to zero as ε → 0 . For these cases we obtain the operators whose spectrum attracts the spectrum of Δε as ε → 0 .The author is grateful to Prof. E.Ya. Khruslov for setting the problem and his attention paid to this work. The work is partially supported by the Grant for Young Scientists of National Academy of Sciences of Ukraine (No. 20207)
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
- …
