Action Principles for Transgression and Chern-Simons AdS Gravities

Chern-Simons gravities are theories with a lagrangian given by a Chern-Simons form constructed from a space-time gauge group. In previous investigations we showed that, for some special field configurations that are solutions of the field equations, the extension from Chern-Simons to Transgression forms as lagrangians, motivated by gauge invariance, automatically yields the boundary terms required to regularize the theory, giving finite conserved charges and black hole thermodynamics. Further work by other researchers showed that one of the action functionals considered in the above mentioned work yields a well defined action principle in the metric (zero torsion) case and for asymptotically Anti de Sitter (AdS) space-times. In the present work we consider several action functionals for Chern-Simons AdS gravity constructed from Transgression forms, and show the action principles to be well defined and the Noether charges and Euclidean action to be finite for field configurations satisfying only that the gauge field curvature (field strength) for the AdS gauge group is asymptotically finite. For that purpose we consider an asymptotic expansion of the vielbein and spin connection that may be regarded as a perturbation of an AdS space-time, but allowing a non zero torsion. Our results are of potential interest for Lovelock gravity theories, as it has been shown that the boundary terms dictated by the transgressions for Chern-Simons gravities are also suitable to regularize Lovelock theories.Comment: The review sections of the present paper may have some overlap with the work of the same author arXiv:1010.5110 (which has not been published in a journal). Version 2: Subsection 6.1 clarifying action principle added, references adde

The 'native speaker' spin: the construction of the English teacher at a language department at a university in central Mexico

This is a study of how teachers, students and administrators in a particular university's language department in Guanajuato, Mexico, construct the English teachers' professional image. The experiences of ten teachers, fourteen students, and two administrators at the Language Department of the University of Guanajuato in Mexico are explored through data obtained from conversations, narratives, critical incidents, e-mail correspondence and field-notes. This thesis began as an investigation of the construction of the 'native/non-native' debate. However, it arrived at a final point which is concerned about the ways in which individual perceptions are constructed and affected through historical or social pressures. From the data collected key areas emerged, such as: identity, labelling and the socio-political relationship between Mexico and the United States and its consequences. The data shows the polarization that exists between 'native speakers' and 'non-native speakers' themselves concerning aspects such as birthplace, ethnicity and nationality. In order to make sense of this data, I decided to employ the concept of spin to explain how images of the English teacher and speaker are constructed and maintained (or rejected) by participants. This is used as a lens to understand the evolution of the creation of the 'native speaker' image and labels. This helps understand how the 'native speaker' image came to play such a critical —and sometimes apparently harmful— role in the construction of the Other and the Self. Specifically, the 'native speaker' spin was not a point of investigation, but emerged as a significant tool for the discussion of the data as the analysis progressed. Overall this study seems to set a precedent that there is no clear-cut division between 'native' and 'non-native speakers'. Rising awareness of how complex labels operate through discourses, institutions and hiring policies may help to bring about more recognition of commonalities of English teachers as professionals

Andrés Quintana Roo y Jose María Heredia: protagonistas del primer proyecto cultural del México independiente.

Texto que muestra los aportes que, como iniciadores de los proyectos culturales, a inicios de la independencia en México, ofrecieron José María Heredia y Heredia y Andres Quintana Ro

Actions, equations of motion and boundary conditions for Chern-Simons Branes

Actions for extended objects based on Transgression and Chern-Simons forms for space-time groups and supergroups provide a gauge theoretic framework in which to embed previously studied String and Brane actions, extending them in interesting ways that may be useful in a future non perturbative formulation of String Theory. In this Letter I investigate aspects of the actions of these theories, including equations of motion and boundary conditions, gauge and space-time symmetries, and Dirac quantization of tensions. This theoretical framework is shown to include in certain limit and for a suitable gauge group the standard Bosonic String Theory.Comment: 16 page

Gauged WZW models for space-time groups and gravitational actions

In this paper we investigate gauged Wess-Zumino-Witten models for space-time groups as gravitational theories, following the trend of recent work by Anabalon, Willison and Zanelli. We discuss the field equations in any dimension and study in detail the simplest case of two space-time dimensions and gauge group SO(2,1). For this model we study black hole solutions and we calculate their mass and entropy which resulted in a null value for both.Comment: 26 pages, no figure

Análise evolutiva da morfogênese funcional e tipológica urbana: o caso da rua comercial Santa Ifigênia em São Paulo

O artigo apresenta uma nova abordagem para a análise e compreensão do fenômeno de especialização de ruas comerciais, por meio da aplicação dos princípios teóricos evolutivos ao estudo urbano. A rua paulistana Santa Ifigênia, especializada no comércio varejista dos setoreseletro-eletrônicos e informática, tem servido como suporte da teoria no campo prático.The paper presents a new perspective in order to analyze and comprehend the specialization process of retail streets, through an application of theoretical evolutionary principles to urban study. The street Santa Ifigênia in São Paulo, specialized in electronic and computer retail products, is used as a study case of the theory