1,720,991 research outputs found
Beta functions of a scalar theory coupled to gravity
No full textWe study a scalar field theory coupled to gravity on a flat background, below Plancks energy. Einsteins theory is treated as an effective field theory. Within the context of Wilsons renormalization group we compute gravitational corrections to the functions and the anomalous dimension of the scalar field, taking into account threshold effects. © 1995 The American Physical Society
On the vacuum structure of gauge differential forms.
No full textWe discuss the problem of the existence of theta-vacua for gauge differential forms
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
κ-deformed spacetime from twist
No full textAbstractWe twist the Hopf algebra of igl(n,R) to obtain the κ-deformed spacetime coordinates. Coproducts of the twisted Hopf algebras are explicitly given. The κ-deformed spacetime obtained this way satisfies the same commutation relation as that of the conventional κ-Minkowski spacetime, but its Hopf algebra structure is different from the well-known κ-deformed Poincaré algebra in that it has larger symmetry algebra than the κ-Minkowski case. There are some physical models which consider this symmetry [R. Percacci, Phys. Lett. B 144 (1984) 37; R. Percacci, Geometry of Nonlinear Field Theories, World Scientific, Singapore, 1986; L. Smolin, Nucl. Phys. B 132 (1978) 138; R. Floreanini, R. Percacci, Class. Quantum Grav. 7 (1990) 975]. Incidentally, we obtain the canonical (θ-deformed) non-commutative spacetime from canonically twisted igl(n,R) Hopf algebra
Coleman-Weinberg effect in quantum gravity
No full textThe authors describe an application of the method of the effective potential to a model theory
of gravity with independent vierbein and O (1, 3) connection. Adopting a kind of mean field
approximation, they find that a Coleman-Weinberg effects occurs: radiative corrections due
to loops of the gauge field generate an effective potential for the vierbein whose absolute
minimum corresponds to Minkowski space
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
Supermanifold description of the BRS symmetries of Skewsymmetric tensor gauge fields.
No full textThe authors extend Tulczyjew's geometrical formulation of skewsymmetric tensor gauge fields as connections on generalised principal fibre bundles to the category of supermanifolds. Given a smooth d-dimensional manifold M and a k-form field on it, they construct a suitable supersmooth generalised principal fibre bundle P over a (d,2)-dimensional supermanifold M such that the BRS symmetries of the theory have a natural geometrical interpretation
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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