1,721,079 research outputs found
On the origin of soft X-rays in obscured AGN: answers from high-resolution spectroscopy with XMM-Newton
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Relativistic iron features from X-ray illuminated spots and the measure of the black hole mass in AGN
No full textNarrow spectral features in the 5-6 keV range were recently discovered in the X-ray spectra of a few Active Galactic Nuclei, We propose that these features originate from localized spots occurring on the surface of an accretion disc following its illumination by flares. Detailed calculations of the temporal and spectral properties of these features in our proposed model can be found in Dovčiak et al. (2004). Comparison of the computed profiles with observed features can help to estimate parameters of the system. In principle this method can provide a powerful tool to measure the mass of super-massive black holes in Active Galactic Nuclei. By comparing our calculations with the Chandra and XMM-Newton results, we show, however, that spectra from present generation X-ray satellites are not of good enough quality to fully exploit the method and determine the black hole mass with sufficient accuracy. This task has to be deferred to future missions with both large sensitivity and high energy resolution, such as Constellation-X and Xeus
Evidence for Radiation Pressure Compression in the X-ray Narrow Line Region of Seyfert galaxies
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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
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