1,721,005 research outputs found
Rapid X-ray variability properties during the unusual very hard state in neutron-star low-mass X-ray binaries
No full textHere, we study the rapid X-ray variability (using XMM–Newton observations) of three neutron-star low-mass X-ray binaries (1RXS J180408.9−342058, EXO 1745−248 and IGR J18245−2452) during their recently proposed very hard spectral state. All our systems exhibit a strong to very strong noise component in their power density spectra (rms amplitudes ranging from 34 per cent to 102 per cent) with very low characteristic frequencies (as low as 0.01 Hz). These properties are more extreme than what is commonly observed in the canonical hard state of neutron-star low-mass X-ray binaries observed at X-ray luminosities similar to those we observe from our sources. This suggests that indeed the very hard state is a spectral-timing state distinct from the hard state, although we argue that the variability behaviour of IGR J18245−2452 is very extreme and possibly this source was in a very unusual state. We also compare our results with the rapid X-ray variability of the accreting millisecond X-ray pulsars IGR J00291+5934 and Swift J0911.9−6452 (also using XMM–Newton data) for which previously similar variability phenomena were observed. Although their energy spectra (as observed using the Swift X-ray telescope) were not necessarily as hard (i.e. for Swift J0911.9−6452) as for our other three sources, we conclude that likely both sources were also in very similar state during their XMM–Newton observations. This suggests that different sources that are found in this new state might exhibit different spectral hardness and one has to study both the spectral and the rapid variability to identify this unusual state
Unveiling the nature of compact object in the LMXB MAXI J1957+032 using Swift-XRT
Get PDFMAXI J1957+032 is a transient low-mass X-ray binary (LMXB) that
underwent four short outbursts in 1.5 yr since its discovery in 2015.
The nature of the compact object in MAXI J1957+032 is not clear, but it
was proposed to be a neutron star (NS) based on the short duration of
its outbursts. Here, we report the results obtained after performing
spectral analysis using data obtained with the X-ray telescope aboard
the Neil Gehrels Swift satellite. When describing the spectrum with an absorbed power law,
we found that the spectra softens (the power-law index increases from
∼1.8 to 2.5) as the luminosity decreases. Near the end of its outbursts
the observed value of power-law index (Γ) is ∼2.5. To identify the
nature of the compact object in this system, we used Γ as a tracer of
the spectral evolution with luminosity. We found that for the distance
of 4 kpc, our results suggest that the source harbours a NS
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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