Dirac Matrices for Chern-Simons Gravity

A genuine gauge theory for the Poincar\'e, de Sitter or anti-de Sitter algebras can be constructed in (2n-1)-dimensional spacetime by means of the Chern-Simons form, yielding a gravitational theory that differs from General Relativity but shares many of its properties, such as second order field equations for the metric. The particular form of the Lagrangian is determined by a rank n, symmetric tensor invariant under the relevant algebra. In practice, the calculation of this invariant tensor can be reduced to the computation of the trace of the symmetrized product of n Dirac Gamma matrices \Gamma_{ab} in 2n-dimensional spacetime. While straightforward in principle, this calculation can become extremely cumbersome in practice. For large enough n, existing computer algebra packages take an inordinate long time to produce the answer or plainly fail having used up all available memory. In this talk we show that the general formula for the trace of the symmetrized product of 2n Gamma matrices \Gamma_{ab} can be written as a certain sum over the integer partitions s of n, with every term being multiplied by a numerical coefficient \alpha_{s}. We then give a general algorithm that computes the \alpha-coefficients as the solution of a linear system of equations generated by evaluating the general formula for different sets of tensors B^{ab} with random numerical entries. A recurrence relation between different coefficients is shown to hold and is used in a second, "minimal" algorithm to greatly speed up the computations. Runtime of the minimal algorithm stays below 1 min on a typical desktop computer for up to n=25, which easily covers all foreseeable applications of the trace formula.Comment: v2: 6 pages, no figures. Based on talk presented at I Cosmosul, Rio de Janeiro, Brazil, August 2011. v3: references adde

Managerial Approaches to Telecommuting

The purpose of this theoretical paper is to synthesize the current knowledge on the topic of telecommuter managerial approaches by cross-analyzing certain commonalities and differences among relevant literature and scholarly sources. This paper will explore key themes such as trust management, performance-based reviews, communication, boundary management, work-life balance, and social and professional isolation. Additionally, this analysis will identify significant issues and contradictions amidst the research of flexible work arrangement management styles. Furthermore, it will outline the most significant disadvantages and repercussions of telecommuting and discuss them in relationship to the management styles best suited to alleviating these issues. Then, this paper will develop and present a theory which clearly outlines the best approaches for managing telecommuters by succinctly tying together the crucial variables embodying this literature. After, this paper will provide recommendations and methods for implementing these managerial approaches in the organization. Lastly, this paper will explain the theory’s implications on the overarching knowledge and topic of telecommuter managerial approaches and nature of the workforce

Faster ASV decomposition for orthogonal polyhedra using the Extreme Vertices Model (EVM)

The alternating sum of volumes (ASV) decomposition is a widely used technique for converting a B-Rep into a CSG model. The obtained CSG tree has convex primitives at its leaf nodes, while the contents of its internal nodes alternate between the set union and difference operators. This work first shows that the obtained CSG tree T can also be expressed as the regularized Exclusive-OR operation among all the convex primitives at the leaf nodes of T, regardless the structure and internal nodes of T. This is an important result in the case in which EVM represented orthogonal polyhedra are used because in this model the Exclusive-OR operation runs much faster than set union and difference operations. Therefore this work applies this result to EVM represented orthogonal polyhedra. It also presents experimental results that corroborate the theoretical results and includes some practical uses for the ASV decomposition of orthogonal polyhedra.Postprint (published version

Body mass index as a standard of living measure: a different interpretation for the case of Colombia.

We analyze the Body Mass Index (BMI) in a distinct way of its traditional use and it lets us use it as a proxy of standard of living for the case of Colombia. Our approach is focused on studying how far the people are from the normal range and not on the score of each one and this lets us to treat equally extreme cases as severe thinness and obesity. We use a probabilistic model (Ordered Probit) that evaluates the probability of being within the normal range or another level. We found that socioeconomic variables have a significant effect on the dependent variable and that there are no linear effects. Besides, people with difficulties for walking and adults have less probability of having a normal BMI.Standard of Living, Body Mass Index, Overweight

La teoría literaria latinoamericana

1 archivo PDF (21 páginas). tyvlxliiiEn este trabajo busco responder a la pregunta de si existe o no una teoría literaria latinoamericana. Para ello reviso primero el concepto de teoría a fin de determinar de qué modo puede aplicarse a la literatura. Enseguida reflexiono sobre la relaciones que guardan, en el ámbito de los estudios literarios: teoría, crítica y metodología, y sus vínculos con los tres vértices sobre los que se configura la crítica: autor, obra, lector. Así, distingo entre las teorías cuyo destino es convertirse en antropologías filosóficas, donde el entendimiento acerca del objeto de estudio resulta sólo pretextual; teorías cuyas pretensiones son de objetividad y se convierten cómodamente en metodologías, pues ayudan a mirar la obra desde un lugar profético y sistematizado; finalmente hablo de las críticas parafrásticas, las cuales elaboran un discurso paralelo, metafórico, con el cual dicen analizar la obra y las motivaciones del autor. Todo esto implica una noción de literatura que contrasta con la de los teóricos de la transculturación y con las prácticas literarias, por ejemplo, en lenguas indígenas. Ello nos permite defender que no sólo la literatura sino también su crítica están condicionadas socialmente. En este sentido, la teoría y crítica literarias latinoamericanas están ligadas a un principio de representatividad que inevitablemente se transforma en una actividad cognoscitiva, en un ejercicio epistemológico sobre nuestra peculiaridad cultural y sobre nuestra literatura. ABSTRACT: My paper aims at answering if there is such a thing as a Latin-American literary theory. So, I first review the concept of theory to pinpoint how it can be linked to the literary. Afterwards, I reflect on the ways theory, criticism, and methodology are related to the three concepts criticism is based on: author, work, and reader. I finally differentiate two areas. The first one is comprised by the theories that would eventually develop into anthropological philosophies and that bring about a pre-textual understanding of the object of study. Such theories display a pretended objectivity and they easily develop into methodologies since they approach the literary work from a prophetic and systematic viewpoint. The second one includes paraphrastic criticism, or the theories that produce a parallel, metaphoric discourse with which they claim they analyze the work and authorial motivations. The proposal as a whole implies a notion of literature distant from transculturalist theories and from practices such as the literatures in indigenous languages. It also opens up the idea of socially conditioned literatures and literary criticisms. In this sense, Latin American theory and literary criticism are connected to a principle of representativity that turns into a cognoscitive activity, an epistemological essay on our cultural particularities and on our literature. PALABRAS CLAVE: Teoría de la literatura. Heurística. Teoría literaria latinoamericana. Crítica literaria. Estudios culturales. “el ser latinoamericano”. Transculturación. Heterogeneidad. KEY WORDS: Literary theory. Heuristics. Latin American literary theory. Literary criticism. Cultural studies. “the Latin American subject”. Transculturation. Heterogeneity

Francisco Tario : una narrativa de la ajenidad

1 archivo PDF (16 páginas). tyvlxlivLos cuentos de Francisco Tario suelen calificarse como literatura fantástica. Si nos atenemos a la caracterización que del género hacen Roger Caillois y Tzvetan Todorov, veremos que, en general, la obra cuentística del autor de Una violeta de más no resulta fantástica y, si ampliamos la revisión a sus novelas, descubrimos una constante en su narrativa: el efecto de extrañamiento sobre la condición humana, la ajenidad que provocan en sus narradores las apariencias. Pasamos por las cosas sin notarlas. Lo importante termina siendo averiguar otro punto de vista, hablar de los deseos y decepciones del ser humano, pero desde la mirada de los objetos, desde la mirada del otro, cual etnógrafo al que le estalla el mundo y debiera comprenderlo, un mundo que ha sido suyo pero que de pronto le resulta extraño. Las cosas, los locos, los artistas, los fantasmas, la casa-personaje refugio del tiempo, todos son heterónimos de una misma necesidad: la de reconocer la vida, el lado profundo y olvidado de las cosas, pero también su carácter deceptivo. La maniobra fantástica y memorística es sólo una forma de delación existencialista, una escapatoria ontológica, una rebelión escéptica, la confesión de que escribir, al final, resulta una pasión inútil. ABSTRACT: The stories of Francisco Tario tend to be classified as fantastic literature. If we consider the definition of this genre made by Roger Caillois and Tzvetan Todorov, we will see that in general, the stories of the author of Una violeta de más are not fantastic, and if we extend this analysis to his novels, we discover a constant in his narrative: the effect of estrangement on the human condition, the otherness provoked in his narrators by appearances. We go past things without noticing them. The important things in life end up being discovering another point of view, talking about the desires and deceptions of human beings, but from the perspective of objects, from the other, as an ethnographer whose world has exploded and he needs to understand it, a world that has been his but which suddenly seems strange. Things, craziness, artists, ghosts, the house-character refuge of time, are all heteronyms of one same need: that to recognize life, the deep and forgotten side of things, but also its deceptive character. The fantastic maneuver and the use of memory are just an existential betrayal, an ontological escapade, a skeptic rebellion, the confession that writing, in the end, results in a useless passion. PALABRAS CLAVE: Francisco Tario, lo fantástico, mirada etnográfica, escapatoria ontológica, pasión inútil. KEY WORD: Fantastic genre, ethnographic view, ontological escape, useless passion