1,721,451 research outputs found
Study of hypernuclei in the reaction 6Li+ I2C at 2 A Oe V
No full textCette thèse présente une nouvelle approche expérimentale proposée par la collaboration HypHI pour l’étude des hypernoyaux dans des réactions induites par des faisceaux d’ions lourds stables ou radioactifs. La méthode proposée permet de mesurer les hypernoyaux formés par coalescence entre un hypéron Λ produit dans la région des participants et un fragment spectateur issu du projectile. Ce mode de production offre la possibilité d’étudier les hypernoyaux dans des conditions extrêmes d’isospin et de mesurer directement leur moment magnétique hypernucléaire. Une première expérience ayant pour objectif principal de démontrer la faisabilité de la nouvelle méthode proposée, a été réalisée en effectuant une spectroscopie précise des hypernoyaux 4 ΛH, 3 ΛH et 5 ΛHe produits dans les collisions 6Li+12C à une énergie incidente de 2 GeV par nucléon. La conception, le développement et la réalisation du nouveau dispositif de détection sont présentés. Les performances des détecteurs, ainsi que celles du système de déclenchement ont été étudiées.
Le code d’analyse développé pour la reconstruction des hypernoyaux est présenté ainsi que ses performances sur les données simulées. L’analyse des données expérimentales et
les premiers résultats de la reconstruction de l’hypéron Λ et de l’hypernoyau 5 ΛHe, ainsi que la mesure de leur temps de vie, sont présentés. Ces premiers résultats démontrent
la faisabilité de cette nouvelle approche expérimentale pour l’étude des hypernoyaux et ouvrent de nouvelles perspectives dans la recherche d’hypernoyaux lourds et proches des limites de stabilité.This thesis presents a new experimental approach proposed by the HypHI collaboration to study hypernulei by means of reactions induced by stable and radioactive heavy-ion
beams. The proposed method allows to measure hypernuclei formed by coalescence of a Λ-hyperon produced in the participant region and a projectile spectator fragment. Such
a production mode offers the opportunity to investigate hypernuclei at extreme isospin and to measure directly hypernuclear magnetic moments. A first experiment aiming
at demonstrating the feasibility of this new method has been carried out with a 6Li beam at 2 A GeV impinged on a 12C target by identifying 3 ΛH, 4 ΛH and 5 ΛHe hypernuclei
from their mesonic weak decay modes. The design, development and realization of this experiment are presented. Performances of the detectors and of the trigger system have been investigated. The software analysis developed for the reconstruction of hypernuclei is
presented and its performances are evaluated using simulated data. The data analysis and preliminary results of the reconstruction of Λ hyperons and of 5 ΛHe and the measurement of their lifetime are reported. The results demonstrate the feasibility of the new experimental
approach for the study of hypernuclei and open new perspectives to investigate heavier hypernuclei toward the proton and neutron drip lines
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
Production of charm-strange mesons in proton-proton and proton-lead collisions with the ALICE experiment at LHC
No full textL'étude de la production des quarks charmés dans les collisions de hautes énergies de noyaux atomiques offre une approche inédite pour l'étude du plasma de quarks et de gluons. La compréhension et la caractérisation de cet état de la matière déconfinée, de prime abord retrouvé dans les systèmes les plus lourds, nécessitent une connaissance fine des systèmes les plus légers, telles que les collisions proton-proton (pp) et proton-plomb (p-Pb). Dans ce manuscrit, nous présentons la mesure de la production des mésons charmés-étranges Ds+, à rapidité centrale, avec les données du run 2 du LHC, recueillies en 2016 par l'expérience ALICE. Deux systèmes sont étudiés : les collisions pp à √s=13 TeV et p-Pb à √sNN=5,02 TeV. La section efficace de production des Ds+, leur abondance relative et leur facteur de modification nucléaire sont mesurés puis comparés à d'autres mesures et à diverses prédictions théoriques. Le résultat p-Pb établit une nouvelle référence pour l'étude des collisions Pb-Pb.The study of the production of charm quarks in high-energy atomic-nucleus collisions offers an genuine approach for the study of the quark-gluon plasma. The understanding and characterisation of this state of deconfined-matter, at first sight created in heaviest systems, require a fine knowledge of lightest systems, such as proton-proton (pp) and proton-lead (p-Pb) collisions. In this manuscript, we present the measurement of the charm-strange mesons Ds+ production, at central rapidity, with the LHC run 2 data, collected in 2016 with the ALICE experiment. Two systems are studied: pp collisions at √s=13 TeV and p-Pb collisions at √sNN=5.02 TeV. The production cross-section of Ds+, their relative abundance and their nuclear modification factor are measured then compared to other measurements and to various theoretical predictions. The p-Pb result establishes a new reference for the study of Pb-Pb collisions
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
Kinematical properties of spectator fragments in heavy-ion collisions at relativistic energies
No full textLes collisions d’ions lourds aux énergies relativistes permettent de faire atteindre à la matière nucléaire des conditions extrêmes en température et en densité. La géométrie des collisions permet de définir la matière « spectatrice » (constituée de rémanents des projectiles initiaux) par opposition à la matière « participante ». La mesure de la vitesse des fragments spectateurs (identifiés en masse et en charge) avec une très grande précision, telle qu’accessible auprès du spectromètre FRS du laboratoire GSI de Darmstadt, renseigne sur les propriétés de la matière nucléaire. Ainsi, le freinage progressif des fragments avec la perte de masse engendrée dans la collision pourrait être lié à la section efficace nucléon-nucléon dans le milieu. D’autre part, la compréhension de la dispersion cinématique observée conduit à la caractérisation des divers processus de formation des fragments (multifragmentation, évaporation de fragments de masses intermédiaires). La combinaison de ces informations avec les sections efficaces de production permet une évaluation du lien entre ces processus et le paramètre d’impact (facilitant la comparaison aux prédictions théoriques). Une formule analytique pour la déviation standard de l’impulsion longitudinale est développée ; son universalité et sa prédictivité en font un bon outil pour des estimations pratiques.Heavy-ion collisions at relativistic energies are the main tool to reach extreme conditions of temperature and density with the nuclear matter. The geometry of the collisions defines the “spectator” matter (formed by residues from projectiles) by contrast with the “participant” matter. The high-precision velocity measurement of fully identified (charge and mass) spectator fragments –as is achievable with the FRS spectrometer in GSI Darmstadt- carries information on the properties of nuclear matter. Indeed, the slowing down of the fragments with decreasing mass may be linked with the in-medium nucleon-nucleon cross-section. Furthermore, the comprehension of the observed kinematical dispersion leads to the characterization of the various processes of fragment formation (multifragmentation, evaporation of intermediate-mass fragments). The combination of such information with the production cross-sections allows an evaluation of the dependence of these processes with the impact parameter (making the comparison with theoretical predictions easier). An analytical formula for the standard deviation of longitudinal momentum is developed; its universality and its predictive power make it a good tool for practical evaluations
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
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