1,721,233 research outputs found
Measurement of 139La (n, gamma) Cross Section
No full textThe capture cross section of the 139La has been measured relative to 197 Au standard in the energy range of 0.6 eV-9 keV at n_TOF, the neutron time-of-flight facility at CERN. After a description of the experimental apparatus we provide here the data analysis procedures. Finally, the capture data allow to determine the Maxwellian-averaged capture cross section together with the abundance synthesized by the main component of the s process
Measurement of 139-La (n,gamma) Cross Section at n_TOF
No full textThe capture cross section of the 139La has been measured relative to 197Au standard at n_TOF. We provide here a short description of the experimental apparatus and of the data analysis procedures. The extracted resonance parameters allow to calculate the fundamental nuclear quantities such as average spacing &l D >1=0 = 268 + /- 22 eV, &l D >l=l &l 250 eV neutron strength functions SO =(0.79 + / - 0.03)x0.0001, and S1 = (0.73 + / - 0.05)x0.0001 and the Maxwellian-averaged capture cross section (MACS). The MACS is particularly useful far the determination of the abundance synthesized by the main component of the s process
Measurement of the Resonance Capture Cross Section of 204,206Pb and Termination of the s-process
No full textThe neutron capture cross sections of 204Pb and 206Pb have been measured at the CERN n_TOF installation using the time of flight method with the pulse height weighting technique. Main improvements versus previous measurements concern the capture experimental setup, which has been optimized in terms of low neutron sensitivity. In the analysis of 204Pb we report new capture cross sections for two strong s-wave resonances below 2.5 keV, which enhance the Maxwellian Average Cross Section at kT = 5 keV by about a factor of two with respect to the recommended values. In 206Pb we have determined new capture cross sections for a large number (97) of resonances, which were not observed in previous measurements. We discuss preliminary implications of the new cross sections in the stellar nucleosynthesis of the Pb isotopes
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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