1,721,065 research outputs found
Relationships between various characterisations of wave tails
No full textOne can define several properties of wave equations that correspond to the absence of tails in their solutions, the most common, by far, being Huygens' principle. Not all of these definitions are equivalent, although they are sometimes assumed to be. We analyse this issue in detail for linear scalar waves, establishing some relationships between the various properties. Huygens' principle is almost always equivalent to the characteristic propagation property and in two spacetime dimensions the latter is equivalent to the zeroth-order progressing-wave propagation property. Higher-order progressing waves, in general, do have tails and do not seem to admit a simple physical characterization, but they are nevertheless useful because of their close association with exactly solvable two-dimensional equations
VELA: The CMOS circuit based on fast current read-out for X-ray spectroscopy with DePMOS
No full textDePMOS based Active Pixel Sensor (APS) matrix is a new detector concept for X-ray imaging and spectroscopy applications. This type of X-ray detector can provide excellent energy resolution and high-speed readout. Both these features and the advantage of random pixel accessibility can fulfill the requirements of new space applications, like the XEUS Wide Field Imager. In a matrix arrangement, each pixel must be read out by a time variant filter, so a new readout mechanism and a proper multi-channel integrated shaping amplifier are needed. To operate at the required fast processing time (e.g., 4 μs per line) DePMOS transistor cannot be operated in the classical source follower configuration, because this results in a long settling time. So a new design for multi-channel readout of the DePMOS matrix has to be considered. We propose a new fast readout concept, which is based on the DePMOS drain current readout and processing. © 2007 IEEE
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
Fast DEPFET current readout for X-ray astronomy missions
No full textThe DEPFET-based Active Pixel Sensor (APS) matrix is a new detector concept for X-ray imaging and spectroscopy applications. This type of detector can provide excellent energy resolution and high-speed readout. Both of these features, along with the advantage of random pixel accessibility, can fulfill the requirements of new imaging applications in the X-ray band. In a matrix arrangement, each pixel must be read Out by a time-variant filter, so a proper multi-channel integrated filtering amplifier is needed. To operate large area matrices at very fast processing times, we have recently proposed a Current readout configuration. in this paper, we explore the performance offered by this circuit when operated with a DEPFET matrix, specifically concerning its ultimate speed capabilities and the trade-off achieved between electronics noise and processing time. (C) 2009 Elsevier B.V. All rights reserved
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
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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