1,720,985 research outputs found
Relation between the continuum threshold and the Polyakov loop with the QCD deconfinement transition
Full text linkUsing vector and axial-vector correlators within finite-energy sum rules with inputs from a chiral quark model, coupled to the Polyakov loop, with nonlocal vector interactions, we extend our previous work to confirm the equivalence between the continuum threshold s0 and the trace of the Polyakov loop Φ as order parameters for the deconfinement transition at finite temperature T and quark chemical potential μ. The obtained results are in agreement with our initial conclusion, where we showed that s0(T,μ) and Φ(T,μ) provide the same information for the QCD deconfinement transition.Fil: Carlomagno, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; ArgentinaFil: Loewe, Marcelo. Pontificia Universidad Catolica de Chile. Facultad de Física. Departamento de Física; Chile. University of Cape Town; Sudáfric
Chemical sensing with graphene: A quantum field theory perspective
Full text linkWe studied theoretically the effect of a low concentration of adsorbed polar molecules on the optical conductivity of graphene, within the Kubo linear response approximation. Our analysis is based on a continuum model approximation that includes up to next-to-nearest neighbors in the pristine graphene effective Hamiltonian. Our results show that the conductivity can be expressed in terms of renormalized quasiparticle parameters vF , M , and μ that include the effect of the molecular surface concentration ndip and dipolar moment P, thus providing a quantum field theory approach to model a graphene-based chemical sensor.Fil: Falomir, Horacio Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Loewe, Marcelo. Pontificia Universidad Católica de Chile; ChileFil: Muñoz, Enrique. Pontificia Universidad Católica de Chile; Chil
Optical conductivity in an effective model for graphene: finite temperature corrections (015401)
Full text linkIn this article, we investigate the temperature and chemical potential dependence of the optical conductivity of graphene, within a field theoretical representation in the continuum approximation, arising from an underlying tight-binding atomistic model, that includes up to second-nearest neighbors coupling. Our calculations allow us to obtain the dependence of the optical conductivity on frequency, temperature and finite chemical potential, thus generalizing our previously reported calculations at zero temperature, and reproducing the universal and experimentally verified value at zero frequency. Moreover, we also show that a small but still measurable shift in the conductance minimum arises as a function of the second-nearest neighbors hopping t´, thus providing the possibility to directly measure this parameter in transport experiments.Fil: Falomir, Horacio Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Muñoz, Enrique. Facultad de Física, Pont. Univ. Católica de Chile; ChileFil: Loewe, Marcelo. Facultad de Física, Pont. Univ. Católica de Chile; ChileFil: Zamora, Renato. Universidad Diego Portales; Chil
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
Optical conductivity and transparency in an effective model for graphene
No full textMotivated by experiments confirming that the optical transparency of graphene is defined through the fine structure constant and that it could be fully explained within the relativistic Dirac fermions in a two-dimensional picture, we investigate in this article how this property is affected by next-to-nearest-neighbor coupling in the low-energy continuum description of graphene. A detailed calculation within the linear response regime allows us to conclude that, somewhat surprisingly, the optical conductivity at zero temperature that determines the transparency remains robust up to this correction.Fil: Falomir, Horacio Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Loewe, Marcelo. University Of Cape Town; Estados Unidos. Universidad Técnica Federico Santa María; Chile. Pontificia Universidad Católica de Chile; ChileFil: Muñoz, Enrique. Pontificia Universidad Católica de Chile; ChileFil: Raya, Alfredo. Universidad Michoacana de San Nicolás de Hidalgo; Méxic
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
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