1,721,411 research outputs found
On charm and beauty in dielectron measurements - Dielectron production in p-Pb collisions at TeV with ALICE
No full textOne possibility to study the quark-gluon plasma created in ultra-relativistic heavy-ion collisions is to measure modifications of an established baseline and by this infer on the interaction of a given probe with the created medium. A prominent way to introduce this baseline is through measurements in pp collisions. However, it is known that the binding effects of the proton in a heavy nucleus can modify said baseline without the creation of a quark-gluon plasma. In order to study such cold nuclear matter effects one can study collisions with a smaller transverse size and density, such as proton-lead (p-Pb) collisions. This thesis presents the analysis of dielectron production in p-Pb collisions at a collision energy in the centre of mass system of TeV as a function of the invariant mass and the momentum of the e+e- pair. The main purpose of the analysis is to study modifications with respect to scaling expectations of the contribution of heavy-flavour production and their impact on the measured dielectron yield. This is done by measuring the dielectron yield in p-Pb collisions and comparing it to baseline expectations. The baseline for light flavour hadron decays is constructed based on measurements in \ppb collisions at TeV. The heavy-flavour contribution uses the measured production cross sections of heavy quarks in pp collisions and assumes a scaling of the production cross section with the number of binary nucleon-nucleon collisions. It is found that the baseline constructed in this way is able to describe the data within the experimental uncertainties. To investigate the impact of a possible modification of the contribution of the charm hadron decays to the dielectron spectrum, model calculations based on globally available data are included in the charm baseline. This reduces the expected contribution and a tension starts to arise in the mass region dominated by the heavy-flavour contributions. The possibility of an additional source of dielectrons produced as thermal radiation from a hot and dense medium formed in p-Pb collisions is investigated by also including such a source in the comparisons. The conclusion drawn from the presented measurement and its comparisons to baseline calculations under different assumptions is that no significant suppression of the charm contribution due to cold nuclear matter effects is present in the dielectron spectrum. However, it is possible that the suppression could be present but is offset due to the presence of a thermal source of dileptons, keeping the overall dilepton rate constant. The discussion finishes with an outlook on future measurements that might be able to resolve this ambiguity
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
Dielectron Production in Proton–Proton Collisions at <em>√s</em>=7 TeV with ALICE
No full textThe ALICE Collaboration measured dielectron production as a function of the invariant mass ( m ee ), the pair transverse momentum ( p T , ee ) and the pair distance of closest approach ( DCA ee ) in pp collisions at s = 7 TeV. Prompt and non-prompt dielectron sources can be separated with the DCA ee , which will give the opportunity in heavy-ion collisions to identify thermal radiation from the medium in the intermediate-mass range dominated by contributions from open-charm and beauty hadron decays. The charm and beauty total cross sections are extracted from the data by fitting the spectra with two different MC generators, i.e., PYTHIA a leading order event generator and POWHEG a next-to-leading order event generator. Significant model dependences are observed, reflecting the sensitivity of this measurement to the heavy-flavour production mechanisms
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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