1,720,977 research outputs found
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
Développements théoriques pour les jets dans les collisions d’ions lourds
No full textThe quark-gluon plasma (QGP) is an exotic phase of matter, composed of deconfined quarks and gluons and is briefly created in heavy-ion collisions (HIC) at the LHC and at the RHIC. High-energy, self-collimated structures of final-state particles also created in HIC, called jets, probe the QGP, piercing through it on their way to the particle detector. In particular, as the jet propagates, it is quenched, shedding its energy through its interaction with the QGP. Quantum field theory at finite temperature – thermal field theory, is then an extremely powerful tool, capable of analytically quantifying how such a high-energy object interacts with a weakly coupled thermal bath. In this thesis, we work towards the computation of corrections (in the expansion of the strong coupling constant) to two quantities, which dictate how jets are quenched by the QGP. The first being the transverse momentum broadening coefficient, which describes how the jet diffuses in transverse momentum space through its interaction with the medium. We focus on the computation of logarithmically enhanced corrections, carefully showing how the thermal scale affects the logarithmic phase space. The second is the asymptotic mass, which can be thought of as a shift in the jet’s dispersion relation as it undergoes forward scattering with the medium’s constituents. We complete a matching calculation, which rids the mass’ classical corrections of any unphysical divergences, while also beginning the completion of its full two-loop, quantum correctionsLe plasma de quarks et de gluons (QGP) est une phase exotique de la matière composée de quarks et de gluons déconfinés. Il se forme brièvement lors des collisions d’ion lourds (HIC) au LHC et RHIC. Dans le cadre de ces collisions, des structures hautement énergétiques d'états finaux, connues sous le nom de jets, servent de sondes idéales. Ces jets pénètrent le QGP en chemin vers les détecteurs de particules. Lorsque le jet se propage il est éteint, perdant son énergie par son interaction avec le QGP. La théorie quantique des champs à température finale – la théorie des champs théoriques, est un outil extrêmement puissant qui est capable de quantifier analytiquement la façon dont un objet de si haute énergie interagit avec un bain thermique faiblement couplé. Dans cette thèse, notre travaille se concentre sur le calcul des corrections (dans l'expansion de la constante de couplage fort) de deux quantités, qui déterminent la manière dont les jets sont éteints par le QGP. Le premier est le coefficient d'élargissement du moment transverse, qui décrit comment le jet se diffuse dans l'espace du moment transverse par son interaction avec le milieu. Notre attention se porte sur le calcul des corrections logarithmiques associées à cette quantité. La seconde est la masse asymptotique, qui peut être considérée comme un changement dans la relation de dispersion du jet lorsqu'il subit une diffusion vers l'avant avec les constituants du milieu. Nous effectuons un calcul correspondant, en nous basant sur certains résultats de la littérature pour débarrasser les corrections classiques de la masse de toute divergence non physique, tout en commençant à compléter ses corrections complètes à une boucl
Classical vs. quantum corrections to jet broadening in a weakly coupled QGP
No full textInternational audienceWe compute double-logarithmically enhanced corrections to at relative order in the setting of a weakly coupled quark-gluon plasma, observing how the thermal scale affects the region of phase space, which gives rise to these corrections. We furthermore clarify how the region of phase from which these corrections are borne is situated with respect to that from which the classical corrections arise at relative order . This represents a significant step towards our eventual goal of understanding which class of corrections dominate, thereby pushing forward our quantitative grasp on the phenomenon of jet quenching in heavy-ion collisions
Développements théoriques pour les jets dans les collisions d’ions lourds
No full textThe quark-gluon plasma (QGP) is an exotic phase of matter, composed of deconfined quarks and gluons and is briefly created in heavy-ion collisions (HIC) at the LHC and at the RHIC. High-energy, self-collimated structures of final-state particles also created in HIC, called jets, probe the QGP, piercing through it on their way to the particle detector. In particular, as the jet propagates, it is quenched, shedding its energy through its interaction with the QGP. Quantum field theory at finite temperature – thermal field theory, is then an extremely powerful tool, capable of analytically quantifying how such a high-energy object interacts with a weakly coupled thermal bath. In this thesis, we work towards the computation of corrections (in the expansion of the strong coupling constant) to two quantities, which dictate how jets are quenched by the QGP. The first being the transverse momentum broadening coefficient, which describes how the jet diffuses in transverse momentum space through its interaction with the medium. We focus on the computation of logarithmically enhanced corrections, carefully showing how the thermal scale affects the logarithmic phase space. The second is the asymptotic mass, which can be thought of as a shift in the jet’s dispersion relation as it undergoes forward scattering with the medium’s constituents. We complete a matching calculation, which rids the mass’ classical corrections of any unphysical divergences, while also beginning the completion of its full two-loop, quantum correctionsLe plasma de quarks et de gluons (QGP) est une phase exotique de la matière composée de quarks et de gluons déconfinés. Il se forme brièvement lors des collisions d’ion lourds (HIC) au LHC et RHIC. Dans le cadre de ces collisions, des structures hautement énergétiques d'états finaux, connues sous le nom de jets, servent de sondes idéales. Ces jets pénètrent le QGP en chemin vers les détecteurs de particules. Lorsque le jet se propage il est éteint, perdant son énergie par son interaction avec le QGP. La théorie quantique des champs à température finale – la théorie des champs théoriques, est un outil extrêmement puissant qui est capable de quantifier analytiquement la façon dont un objet de si haute énergie interagit avec un bain thermique faiblement couplé. Dans cette thèse, notre travaille se concentre sur le calcul des corrections (dans l'expansion de la constante de couplage fort) de deux quantités, qui déterminent la manière dont les jets sont éteints par le QGP. Le premier est le coefficient d'élargissement du moment transverse, qui décrit comment le jet se diffuse dans l'espace du moment transverse par son interaction avec le milieu. Notre attention se porte sur le calcul des corrections logarithmiques associées à cette quantité. La seconde est la masse asymptotique, qui peut être considérée comme un changement dans la relation de dispersion du jet lorsqu'il subit une diffusion vers l'avant avec les constituants du milieu. Nous effectuons un calcul correspondant, en nous basant sur certains résultats de la littérature pour débarrasser les corrections classiques de la masse de toute divergence non physique, tout en commençant à compléter ses corrections complètes à une boucl
Développements théoriques pour les jets dans les collisions d’ions lourds
No full textThe quark-gluon plasma (QGP) is an exotic phase of matter, composed of deconfined quarks and gluons and is briefly created in heavy-ion collisions (HIC) at the LHC and at the RHIC. High-energy, self-collimated structures of final-state particles also created in HIC, called jets, probe the QGP, piercing through it on their way to the particle detector. In particular, as the jet propagates, it is quenched, shedding its energy through its interaction with the QGP. Quantum field theory at finite temperature – thermal field theory, is then an extremely powerful tool, capable of analytically quantifying how such a high-energy object interacts with a weakly coupled thermal bath. In this thesis, we work towards the computation of corrections (in the expansion of the strong coupling constant) to two quantities, which dictate how jets are quenched by the QGP. The first being the transverse momentum broadening coefficient, which describes how the jet diffuses in transverse momentum space through its interaction with the medium. We focus on the computation of logarithmically enhanced corrections, carefully showing how the thermal scale affects the logarithmic phase space. The second is the asymptotic mass, which can be thought of as a shift in the jet’s dispersion relation as it undergoes forward scattering with the medium’s constituents. We complete a matching calculation, which rids the mass’ classical corrections of any unphysical divergences, while also beginning the completion of its full two-loop, quantum correctionsLe plasma de quarks et de gluons (QGP) est une phase exotique de la matière composée de quarks et de gluons déconfinés. Il se forme brièvement lors des collisions d’ion lourds (HIC) au LHC et RHIC. Dans le cadre de ces collisions, des structures hautement énergétiques d'états finaux, connues sous le nom de jets, servent de sondes idéales. Ces jets pénètrent le QGP en chemin vers les détecteurs de particules. Lorsque le jet se propage il est éteint, perdant son énergie par son interaction avec le QGP. La théorie quantique des champs à température finale – la théorie des champs théoriques, est un outil extrêmement puissant qui est capable de quantifier analytiquement la façon dont un objet de si haute énergie interagit avec un bain thermique faiblement couplé. Dans cette thèse, notre travaille se concentre sur le calcul des corrections (dans l'expansion de la constante de couplage fort) de deux quantités, qui déterminent la manière dont les jets sont éteints par le QGP. Le premier est le coefficient d'élargissement du moment transverse, qui décrit comment le jet se diffuse dans l'espace du moment transverse par son interaction avec le milieu. Notre attention se porte sur le calcul des corrections logarithmiques associées à cette quantité. La seconde est la masse asymptotique, qui peut être considérée comme un changement dans la relation de dispersion du jet lorsqu'il subit une diffusion vers l'avant avec les constituants du milieu. Nous effectuons un calcul correspondant, en nous basant sur certains résultats de la littérature pour débarrasser les corrections classiques de la masse de toute divergence non physique, tout en commençant à compléter ses corrections complètes à une boucl
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