1,721,015 research outputs found
Holographic oddballs
Full text linkThe spectrum of the glueball with J(PC) = 0(--) is computed using different bottom-up holographic models of QCD. The results indicate a lowest-lying state lighter than in the determination by other methods, with mass m similar or equal to 2.8 GeV. The in-medium properties of this gluonium are investigated, and stability against thermal and density effects is compared to other hadronic systems. Production and decay modes are identified, useful for searching the J(PC) = 0(--) glueball
On thermalization of a boost-invariant non-Abelian plasma
Full text linkUsing a holographic method, we further investigate the relaxation towards the hydrodynamic regime of a boost-invariant non-Abelian plasma taken out-of-equilibrium. In the dual description, the system is driven out-of-equilibrium by boundary sourcing, a deformation of the boundary metric, as proposed by Chesler and Yaffe. The effects of several deformation profiles on the bulk geometry are investigated by the analysis of the corresponding solutions of the Einstein equations. The time of restoration of the hydrodynamic regime is investigated: setting the effective temperature of the system at the end of the boundary quenching to T-eff(tau*) = 500 MeV, the hydrodynamic regime is reached after a lapse of time of O(1 fm/c)
Phase diagram of a generalized Winfree model
No full textWe study the phase diagram of a generalized Winfree model. The modification is such that the coupling
depends on the fraction of synchronized oscillators, a situation which has been noted in some experiments on
coupled Josephson junctions and mechanical systems. We let the global coupling k be a function of the
Kuramoto order parameter r through an exponent z such that z=1 corresponds to the standard Winfree model,
z1 strengthens the coupling at low r low amount of synchronization, and at z1, the coupling is weakened
for low r. Using both analytical and numerical approaches, we find that z controls the size of the incoherent
phase region and that one may make the incoherent behavior less typical by choosing z1. We also find that
the original Winfree model is a rather special case; indeed, the partial locked behavior disappears for z1. At
fixed k and varying , the stability boundary of the locked phase corresponds to a transition that is continuous
for z1. This change in the nature of the transition is in accordance with a previous
study of a similarly modified Kuramoto model
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
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