1,721,032 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Lectures on Supergravity p-branes
No full textWe review the properties of classical p-brane solutions to supergravity theories, i.e. solutions that may be interpreted as Poincare-invariant hyperplanes in spacetime. Topics covered include the distinction between elementary/electric and solitonic/magnetic solutions, examples of singularity and global structure, relations between mass densities, charge densities and the preservation of unbroken supersymmetry, diagonal and vertical Kaluza-Klein reduction families, Scherk-Schwarz reduction and domain walls, and the classification of multiplicities using duality symmetries
Non-critical Gravities and Integrable Models
Get PDFWe review the origin of anomaly-induced dynamics in theories of gravity from a BRST viewpoint and show how quantum canonical transformations may be used to solve the resulting Liouville or Toda models for the anomalous modes
Symmetry Orbits of Supergravity Black Holes - In Honor of Andrei Slavnov's 75th Birthday
Get PDF20.03.15 KB Ok to add working paper to spiral.Black hole solutions of supergravity theories form families that realizing the deep nonlinear duality symmetries of these theories. They form orbits under the action of these symmetry groups, with extremal (i.e. BPS) solutions at the limits of such orbits. An important technique in the analysis of such solution families employs timelike dimensional reduction and exchanges the stationary black-hole problem for a nonlinear sigma-model problem. Families of extremal or BPS solutions are characterized by nilpotent orbits under the duality symmetries, based upon a tri-graded or penta-graded decomposition of the corresponding duality-group algebra
Symmetry orbits of supergravity black holes
Get PDF20.03.15 KB. Ok to add accepted version to spiral, subject to 12 months embarg
Variations on the Author
Get PDF“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
Domain Walls and Spaces of Special Holonomy
Get PDFWe review the relations between a family of domain-wall solutions to M-theory
and gravitational instantons with special holonomy. When oxidized into the
maximal-dimension parent supergravity, the transverse spaces of these domain
walls become cohomogeneity-one spaces with generalized Heisenberg symmetries
and a homothetic conformal symmetry. These metrics may also be obtained as
scaling limits of generalized Eguchi-Hanson metrics, or, with appropriate
discrete identifications, from generalized Atiyah-Hitchin metrics, thus
providing field-theoretic realizations of string-theory orientifolds
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Domain Walls and the Universe
Get PDFD=11 supergravity possesses D=5 Calabi-Yau compactified solutions that may be identified with the vacua of the Horava-Witten orbifold construction for M--theory/heterotic duality. The simplest of these solutions naturally involves two 3-brane domain walls, which may be identified with the orbifold boundary planes; this solution also possesses an unbroken symmetry. Consideration of nearby excited solutions, truncated to the zero-mode and invariant sector, yields an effective D=4 heterotic theory displaying chirality and N=1, D=4 supersymmetry
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