1,721,019 research outputs found
XMM-Newton first X-ray detection of the low-ionization broad absorption line quasar PG 1700+518
No full textWe report the first high-energy detection of PG 1700+518, a well-known low-ionization broad absorption line quasar (quasi-stellar object, QSO). Due to previous X-ray non-detection, it was classified as soft X-ray weak QSO. We observed PG 1700+518 with XMM-Newton for about 60 ks divided in three exposures. The spectrum below 2 keV is very steep, Γ ̃ 2.4-3.8, while at higher energies the extremely flat emission (photon index Γ ̃ 0.15, when modelled with a power law) suggests the presence of strong absorption (NH, pl ̃ 2 × 10^23 cm-2, Γ fixed to 1.8) or a reflection-dominated continuum. The broad-band flux is consistent with previous non-detection. Simultaneous European Photon Imaging Camera (EPIC) and Optical Monitor (OM) data confirm its X-ray weakness (observedαox ̃-2.2). The level of obscuration derived from the X-ray spectra of PG 1700+518 cannot explain its soft X-ray nuclear weakness unless a column density of NH≳ 2 × 10^24 cm-2 is present
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
The High Energy view of the Broad Line Radio Galaxy 3C 111
No full text14 páginas, 9 figuras, 5 tablas.-- El Pdf del artículo es la versión pre-print: arXiv:1108.2609v1.-- et al.We present the analysis of Suzaku and XMM–Newton observations of the broad-line radio
galaxy (BLRG) 3C 111. Its high-energy emission shows variability, a harder continuum with
respect to the radio-quiet active galactic nucleus population, and weak reflection features.
Suzaku found the source in a minimum flux level; a comparison with the XMM–Newton data
implies an increase of a factor of 2.5 in the 0.5–10 keV flux, in the 6 months separating the
two observations. The iron K complex is detected in both data sets, with rather low equivalent
width(s). The intensity of the ironKcomplex does not respond to the change in continuum flux.
An ultrafast, high-ionization outflowing gas is clearly detected in the Suzaku/X-ray Imaging
Spectrometer data; the absorber is most likely unstable. Indeed, during the XMM–Newton
observation, which was 6 months after, the absorber was not detected. No clear rollover in
the hard X-ray emission is detected, probably due to the emergence of the jet as a dominant
component in the hard X-ray band, as suggested by the detection above ∼100 keV with the
GSO onboard Suzaku, although the present data do not allow us to firmly constrain the relative
contribution of the different components. The fluxes observed by the γ -ray satellites CGRO
and Fermi would be compatible with the putative jet component if peaking at energies E ∼ 100MeV. In the X-ray band, the jet contribution to the continuum starts to be significant only
above 10 keV. If the detection of the jet component in 3C 111 is confirmed, then its relative
importance in the X-ray energy band could explain the different observed properties in the
high-energy emission of BLRGs, which are otherwise similar in their other multiwavelength
properties. Comparison between X-ray and γ -ray data taken at different epochs suggests that
the strong variability observed for 3C 111 is probably driven by a change in the primary
continuum.LB acknowledges support from the Spanish Ministry of Science and
Innovation through a ‘Juan de la Cierva’ fellowship. Financial support
for this work was provided by the Spanish Ministry of Science
and Innovation, through research grant AYA2009-08059.Peer reviewe
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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