Reality and causality in quantum gravity modified electrodynamics

We present a general description of the propagation properties of quantum gravity modified electrodynamics characterized by constitutive relations up to second order in the correction parameter. The effective description corresponds to an electrodynamics in a dispersive and absorptive non-local medium, where the Green functions and the refraction indices can be explicitly calculated. The reality of the electromagnetic field together with the requirement of causal propagation in a given referrence frame leads to restrictions in the form of such refraction indices. In particular, absorption must be present in all cases and, contrary to the usual assumption, it is the dominant aspect in those effective models which exhibit linear effects in the correction parameter not related to birefringence. In such a situation absorption is linear while propagation is quadratical in the correction parameter.Comment: 15 pages, LaTex, minor changes to clarify some points, version accepted for publicatio

Dimensional reduction as a method to obtain dual theories for massive spin two in arbitray dimensions

Using the parent Lagrangian method together with a dimensional reduction from $D$ to $(D-1)$ dimensions we construct dual theories for massive spin two fields in arbitrary dimensions in terms of a mixed symmetry tensor $T_{A[A_{1}A_{2}... A_{D-2}]}$. Our starting point is the well studied massless parent action in dimension $D$. The resulting massive Stueckelberg-like parent actions in $(D-1)$ dimensions inherits all the gauge symmetries of the original massless action and can be gauge fixed in two alternative ways, yielding the possibility of having either a parent action with a symmetric or a non-symmetric Fierz-Pauli field $e_{AB}$. Even though the dual sector in terms of the standard spin two field includes only the symmetrical part $e_{\{AB\}}$ in both cases, these two possibilities yield different results in terms of the alternative dual field $T_{A[A_{1}A_{2}... A_{D-2}]}$. In particular, the non-symmetric case reproduces the Freund-Curtright action as the dual to the massive spin two field action in four dimensions.Comment: 14 pages, no figures, RevTex 4. Some clarifying comments and references have been adde

Desarrollo sustentable en la facultad de ingeniería mecánica y eléctrica

Con la finalidad de promover una nueva era de responsabilidad social en el área de Desarrollo Sustentable, se pretende socializar un sistema de contabilidad, reporte y evaluación de desempeño ambiental. Esto se puede lograr a través de diagnósticos de carga eléctrica e hidráulica en las escuelas preparatorias y en las facultades de la Institución o Empresa. Para establecer una línea base e identificar, clasificar y tipificar el estado actual de la Institución se llevaran a cabo reportes de diagnóstico que permitan sugerir acciones correctivas para disminuir el impacto sobre el medio ambiente por el uso de energía eléctrica, agua y gas. Finalmente, lo que se busca es evaluar el desempeño “ambiental” en el marco de responsabilidad social. Se trata de evaluar el desempeño ambiental de la Facultad en el contexto del cumplimiento de su responsabilidad social

Lorentz violating electrodynamics

After summarizing the most interesting results in the calculation of synchrotron radiation in the Myers-Pospelov effective model for Lorentz invariance violating (LIV) electrodynamics, we present a general unified way of describing the radiation regime of LIV electrodynamics which include the following three different models : Gambini-Pullin, Ellis et al. and Myers-Pospelov. Such unification reduces to the standard approach of radiation in a dispersive and absortive (in general) medium with a given index of refraction. The formulation is presented up to second order in the LIV parameter and it is explicitly applied to the synchrotron radiation case.Comment: 11 pages, extended version of the talk given by L.F. Urrutia in the VI Mexican School: Approaches to Quantum Gravity, Playa del Carmen, Mexico, Nov. 2004. Minor chages in the text and added reference

Identificación de variables que impactan en la Eficiencia Energética de Secadoras de ropa.

Este artículo presenta el estudio de identificación de variables que mayor impacto tienen en la eficiencia energética de una secadora de ropa de tipo doméstico. También se presenta un análisis funcional donde se describen los procesos físicos que se llevan a cabo durante un ciclo de secado, desde la generación de calor a través de un calentador eléctrico, hasta le extracción de la humedad de ropa a través de tubos de escape. Posteriormente, se delimita el “Proceso de Secado” dentro del tambor de la secadora, como el fenómeno a entender, explicar y modelar para mejorar su eficiencia. Por medio de un diagrama de parámetro (Diagrama P) y un panel de expertos es que se entiende el proceso de secado de ropa, y son determinadas las variables de entrada que el sistema necesita; así como las de salida que el sistema entrega. A través de estudios teóricos previos es como se explica que variables físicas deberán controlarse para obtener una mejor eficiencia energética. Para validar dichos estudios teóricos previos, se plantea modelar experimentalmente el fenómeno de secado, a través de la construcción de un prototipo funcional y un diseño de experimentos (DOE). Con estas actividades se logra determinar que variables tienen el mayor impacto sobre la eficiencia energética en el proceso de secado; logrando identificar que una disminución en 15% de la humedad relativa del aire que entra a la secadora, podría ayudar a disminuir hasta en un 17% el consumo energético. También el estudio reveló las variables físicas que podrían hacer un ciclo de secado de ropa más rápido

Special issue on real-time computer vision in smart cities

According to United Nations, more than half of the population of the Earth now lives in urban areas. The need to rethink the city in efficient and modern ways, including new actors in the scene such as automatic decision makers, has motivated plenty of national and international initiatives to foster ICT research and innovation in this field. For the European Union, the sustainable development of urban areas is a challenge of key importance: it requires new, efficient, and user-friendly technologies and services, thus becoming one of the main topics within the European Research Programme “Horizon 2020”

Laryngeal amyloidosis: An uncommon cause of dysphonia

Introduction: Amyloidosis is used to describe a range of disorders deined by extracellular deposition of abnormal protein ibrils. The larynx is the most common site of localized amyloidosis in the head and neck region and constitutes less than 1% of benign laryngeal lesions. Hoarseness is the most common symptom. Objective: Prospective clinical evaluation of patients with localized laryngeal amyloidosis. Clinical cases: Presented are 4 cases of patients with localized laryngeal amyloidosis who were treated at the Otolaryngology and Head and Neck Surgery Department at the “Dr. José Eleuterio González” University Hospital in Monterrey, Mexico. Three patients underwent phonomicrosurgery by direct microlaryngoscopy with the removal of the amyloid implantation using a cold knife excision with great results. In each patient the major site of involvement was the supraglottis with a small focus on the false vocal cord. A medical work-up, including a complete blood count (CBC), a basic metabolic panel, urinalysis, liver function test, chest X-ray and physical examination were performed to rule out the presence of systemic disease; no amyloidosis or signs of systemic disease were found. Congo red staining conirms the diagnosis of amyloidosis in all surgical specimens. Conclusions: In laryngeal amyloidosis, the treatment should be directed toward the improvement of the voice and the maintenance of the airway

Dual theories for mixed symmetry fields. Spin-two case: (1,1) versus (2,1) Young symmetry type fields

We show that the parent Lagrangian method gives a natural generalization of the dual theories concept for non p-form fields. Using this generalization we construct here a three-parameter family of Lagrangians that are dual to the Fierz-Pauli description of a free massive spin-two system. The dual field is a three-index tensor T, which dinamically belongs to the (2,1) representation of the Lorentz group. As expected, the massless limit of our Lagrangian, which is parameter independent, has two propagating degrees of freedom per space point.Comment: 10 pages, no figure

Phenomenological description of quantum gravity inspired modified classical electrodynamics

We discuss a large class of phenomenological models incorporating quantum gravity motivated corrections to electrodynamics. The framework is that of electrodynamics in a birefringent and dispersive medium with non-local constitutive relations, which are considered up to second order in the inverse of the energy characterizing the quantum gravity scale. The energy-momentum tensor, Green functions and frequency dependent refraction indices are obtained, leading to departures from standard physics. The effective character of the theory is also emphasized by introducing a frequency cutoff. The analysis of its effects upon the standard notion of causality is performed, showing that in the radiation regime the expected corrections get further suppressed by highly oscillating terms, thus forbiding causality violations to show up in the corresponding observational effects.Comment: 14 pages, to be published in Obregon Festschrift 2006, Gen. Rel. and Gra

Condrodisplasia punctata: a propósito de un caso neonatal

Se presenta el caso de un neonato de ocho días de nacido que sufre de condrodisplasia punctata, una displasia esquelética infrecuente que muestra características radiológicas de calcificaciones puntiformes del cartílago en las epífisis y en las vértebras, acompañadas de defectos oculares, dermatológicos, alteraciones del sistema nervioso central y retardo del crecimiento. Se abordan los hallazgos clínicos y radiológicos para su diagnóstico