1,721,377 research outputs found
4. The Crisis and Political Decision-Making Processes: The Impact on European Constitutional Systems
No full textThe effects of a Comptonizing corona on the appearance of the reflection components in accreting black hole spectra
No full text
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
MODELING X-RAY DATA OF BLACK HOLE BINARIES
Full text linkWe test the truncated disc models using multiwavelength (optical/UV/X-ray) data from the 2005 hard state outburst of the black hole SWIFT J1753.5-0127. This system is both fairly bright and has fairly low interstellar absorption, so gives one of the best datasets to study the weak, cool disc emission in this state. We fit these data using models of an X-ray illuminated disc to constrain the inner
disc radius throughout the outburst. Close to the peak, the observed soft X-ray component is consistent with being produced by the inner disc, with its intrinsic emission enhanced in temperature and luminosity by reprocessing of hard X-ray illumination in an overlap region between the disc and corona. This disc emission provides the seed photons for Compton scattering to produce the hard X-ray
spectrum, and these hard X-rays also illuminate the outer disc, producing the optical emission by reprocessing.
However, towards the end of the outburst, all these conclusions may change. The optical points clearly lie on an extrapolation of the hard X-ray flux, which may indicate that the seed photons for Compton scattering are now self-generated in the flow by Cyclo-Synchrotron radiation rather than being from the disc. The weak soft X-ray emission implies a small disc radius, unchanged from the outburst peak, in conflict with the expectations of the truncated disc model. However, this also requires that the energy to power the corona is advected vertically and radially in a dissipationless fashion from the disc. Thus it seems more likely that the soft X-ray component is not direct emission from the disc itself. We show that a similarly dim low/hard state spectrum from XTE J1118+480 puts similar constraints on the soft X-ray emission region, but here the very low interstellar absorption (an order of magnitude smaller than in SWIFT J1753.5-0127) allows detection of a much larger, cooler, UV component which is well fit by a truncated disc. Thus whatever the origin of the additional weak soft X-ray emission (irradiation of the inner face as opposed to the top surface of the inner edge of the disc, residual inner disc left from evaporation, ionised reflection, jet etc), its existence as a clearly separate component from the truncated disc in XTE J1118+480 shows that it does not trace the inner disc radius, so cannot be used to constrain the truncated disc models
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
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