1,721,052 research outputs found
Incremental diffraction coefficients for source and observation at finite distances from an edge
No full textRecently, an incremental theory of diffraction (ITD) has been introduced which provides a self-consistent, highfrequency description of a wide class of scattering phenomena within a unified framework. Explicit expressions of the incremental diffracted field contributions have been obtained for a plane-wave illumination of wedge-shaped configurations and observation points at a finite distance from the incremental point. In this paper, this method is extended to treat the case when both the source and the observation point are at finite distance from the local incremental point along the edge. To this end, a spectral-domain approach is used to derive a spectral-integral representation for the incremental field contribution. The latter is asymptotically evaluated to find high-frequency closed-form expressions which are uniformly valid at any incidence and observation aspects, including caustics and shadow boundaries of the corresponding ray-field description. The expressions of the incremental diffraction coefficients explicitly satisfy reciprocity. Numerical results are presented and compared with those obtained from different techniques. © 1996 IEEE
An incremental theory of diffraction for objects with local cylindrical shape
No full textIn this paper, a quite general systematic procedure is presented for defining incremental field contributions, that may provide effective tools for describing a wide class of scattering and diffraction phenomena at any aspect, within a unitary, self-consistent framework. This is based on a generalization of the localization process for cylindrical canonical problems with elementary source illumination and arbitrary observation aspects. In particular, it is shown that the spectral integral formulation of the exact solution may also be represented as a spatial integral convolution along the axis of the cylinder. Its integrand is then directly used to define the relevant incremental field contribution. This procedure, that will be referred to as a ITD (Incremental Theory of Diffraction) Fourier transform convolution localization process, is explicitly applied to both wedge and circular cylinder canonical configurations, to define incremental diffraction and scattering contributions, respectively. These formulations are asymptotically approximated to find closed form high-frequency expressions for the incremental field contributions. This generalization of the ITD localization process may provide a quite general, systematic procedure to find incremental field contributions that explicitly satisfy reciprocity and naturally lead to the UTD ray field representation, when it is applicable
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
Performance Evaluation of QoS-Aware Optical Packet Switches
No full textIn this paper we evaluate the performance of Bufferless Optical Packet Switches equipped with shared Tunable Optical Wavelength Converters (TOWC) and supporting Quality of Service. The TOWCs sharing is partial, that is each Output Fiber shares one pool of TOWCs shared by all of the packets directed to that Output Fiber. The QoS, expressed in terms of Packet Loss Probability, is differentiated by giving the packets different priorities in accessing both the output wavelengths and the TOWCs. A scheduling algorithm is proposed and its complexity is evaluated. The QoS technique effectiveness is studied by means of a sophisticated analytical model validated by simulation results. The results show that the proposed technique to support QoS allows a good differentiation of the QoS offered to the packets
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
Disruption of beta1 integrin induces keratinocyte stem cell anoikis through the extrinsic apoptotic pathway
No full textATTIVITA’ DEL MICOLATTONE, PRODOTTO DA MICOBACTERIUM ULCERANS, SU CHERATINOCITI IN COLTURA
No full textAppropriate 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
Keratinocytes that adhere most rapidly to type IV collagen and display characteristics of stem cells are protected from apoptosis
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