1,721,019 research outputs found
Hawking radiation from Loop Black Holes
No full textWe review a recent black hole particle production analisys in a regular spacetime metric obtained in a minisuperspace approach to loop quantum gravity. Repeating the Hawking analysis, which leads to a thermal flux of particles at the future infinity, one finds an infinite evaporation time and unitarity recovered due to the regularity of the singularity free spacetime and to the characteristic behavior of the surface gravity
Note on Reflection Positivity in Nonlocal Gravity
No full textA necessary condition for reflection positivity is that the free propagator be positive. Contrary to recent claims in the literature, we show that this is indeed the case for a large class of nonlocal field theories when the mass vanishes. We restrict attention to scalar field theories relevant for weakly nonlocal gravity and gauge theories
Unattainability of the trans-Planckian regime in nonlocal quantum gravity
Full text linkBased on the ultraviolet asymptotic freedom of nonlocal quantum gravity, we show that the trans-Planckian energy regime is unattainable in laboratory experiments. As physical implications, it turns out that the violation of causality, typical of nonlocal field theories, can never be detected in particle accelerators, while the asymptotic freedom of the theory provides an elegant solution to the so called trans-Planckian cosmological problem
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
Spectral Observables and Gauge Field Couplings in Causal Dynamical Triangulations
No full textIn the first part of this Chapter, we discuss the role of spectral observables, describing possible ways to build them from discretizations of the Laplace-Beltrami operator on triangulations, and how to extract useful geometric information. In the second part, we discuss how to simulate the composite system of gauge fields coupled to CDT for generic groups and dimensions, showing results in some specific case and pointing out current challenges
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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