1,721,027 research outputs found
Mass modelling in X-/y-ray astronomy
No full textThe current status of hard X-ray/γ-ray astronomy is briefly reviewed. The next large ESA γ-ray observatory, INTEGRAL, is reviewed both in terms of its instrumentation and its scientific goals. All γ-ray observations are made against a background noise that is large compared with the signal to be measured, which makes understanding of the background crucial. Mass Modelling is currently being developed to enable observatories to better understand their background, improving the quality of data obtained from observations and the sensitivity of the telescope. Much of the current local development of Mass Modelling is driven by the INTEGRAL mission. Mass Modelling within the context of INTEGRAL is reviewed concentrating on The INTEGRAL Mass Model (TIMM).The background within INTEGRAL is composed of three main components: the prompt cosmic rays, the diffuse γ-ray and the induced radioactivity within the satellite and detectors. To model the third component has required the development of a new code (DECAY). The development and testing of the DECAY code is presented. Testing is carried out using three practical examples: bombardment of a crystal by protons in a high-energy beam; modelling of the background within a low Earth orbit satellite; and, modelling of the background within a high altitude balloon. Having introduced TIMM, and the GGOD software suite used to carry out modelling, the results of recent TIMM simulations are presented and discussed.The sensitivity of a telescope is a function of its background and its observing time. The IBIS instrument suffers from a large dead time (� 20%). By reducing the dead time, with a minimal increase in the background count rate, the sensitivity of IBIS could be further improved. Two suggested ways for doing this, segmenting (or zoning) the veto and raising the low-energy thresholds of the veto crystals, are investigated using TIMM.Finally, X-ray observations are presented of the globular cluster 47 Tucanae.</p
Internal combustion engines : applied thermosceinces/ Ferguson Colin R
No full textx, 545 hal.: ill.; 23 cm
Internal combustion engines : applied thermosceinces/ Ferguson Colin R
No full textx, 545 hal.: ill.; 23 cm
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
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