1,721,243 research outputs found
Gamma-ray burst: from the central engine to future observations with athena
No full textGamma-Ray Bursts (GRBs) are among the most luminous and distant sources in the Universe. In the 33% of the GRBs afterglow light curves is observed the presence of one or multiple X-ray flares, which energy ranges from a percent of, up to a value comparable to, the one of prompt emission. X-ray flare are believed to mark the late-time activity of the central engine. The temporal properties of X-ray flares make it difficult to interpret the observed emission in the framework of the external shock scenario. The comprehension of the X-ray flare origin enables to obtain information about the central engine that cannot be directly observed, indeed the first signal detection, due to the prompt emission, occurs at high distances from the central engine it- self. The guideline will be the study of the time variability of the flares observed with XRT instrument on board of the Swift satellite. After that the results from the XRT data analysis will be compared with observations of the prompt events made by the BAT instrument. This will allow to link prompt emission variability with the eventual flares ones. In fact the prompt emission has an high variability with time and if the same variability is confirmed by both BAT and XRT data, it will be a strong proof that X-ray flares are connected with the residual activity of the central engine, and a confirm of the current theoretical model for X-ray flares. The Athena observatory class mission will address the study of GRBs in the X-ray band, allowing the diagnostic of the metal content around the central engine, will answer the open problem of X-ray flares origin at very high redshifts, and finally will address for the first time the detection and characterization of the WHIM. In this regard it is vital for the implementation of the observations to analyze and optimize the performances of the instruments in terms of background and spectroscopy. Therefore the second part of this work is addressed to the study how the performances of the X-IFU instrument could be affected during a Solar Energetic Particle event (SEP
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
GeV flares studies with GLAST LAT
No full textX-ray flares are very common features in GRB light curves, and occur from similar to 100 s up to thousands of seconds after the burst, when the prompt-to-afterglow transition is taking place. In the context of external shock, X-ray flares can be ascribed to a thick-shell fireball produced by a long-duration central engine activity. The X-ray flare photons are expected to interact with the forward shock electrons by inverse Compton thus producing high-energy flares that potentially will be detected by GLAST LAT. Such high-energy components could explain the delayed GeV emission detected by EGRET in GRB 940217. Observations with GLAST LAT will give useful information to constrain the origin of X-ray flares
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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