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Boletín número 13 de asesoramiento al regante. Octubre-Diciembre 200

Time delays, choice of energy-momentum variables, and relative locality in doubly special relativity

Doubly special relativity (DSR) theories consider (quantum-gravity motivated) deformations of the symmetries of special relativity compatible with a relativity principle. The existence of time delays for massless particles, one of their proposed phenomenological consequences, is a delicate question since, contrary to what happens with Lorentz invariance violation scenarios, they are not simply determined by the modification in the particle dispersion relation. While some studies of DSR assert the existence of photon time delays, in this paper we generalize a recently proposed model for time delay studies in DSR and show that the existence of photon time delays does not necessarily follow from a DSR scenario, determining in which cases this is so. Moreover, we clarify long-standing questions about the arbitrariness in the choice of the energy-momentum labels and the independence of the time delay on this choice, as well as on the consistency of its calculation with the relative locality paradigm of DSR theories. Finally, we show that the result for time delays is reproduced in models that consider propagation in a noncommutative spacetime

Textiloma que se presenta como una masa abdominal: presentación de un caso y revisión bibliográfica

El “textiloma” es un término usado para describir aquel material formado por una matriz de algodón que es dejada involuntariamente en alguna cavidad durante la cirugía, y las reacciones secundarias a su presencia en el cuerpo, este término tiene distintos sinónimos, los más conocidos son: gossypiboma, corpus allienum, oblitoma y gasa o textil retenido. La sintomatología es inespecífica y puede simular diversos padecimientos dependiendo de la región que se encuentre comprometida y el tiempo que transcurra desde el procedimiento quirúrgico.Textiloma o gossypiboma es el término acuñado para describir una masa compuesta por una matriz de algodón que es olvidado en una cavidad, posterior a una intervención quirúrgica. Se calcula una incidencia aproximada de 1 de cada 100 a 5,000 cirugías. Sin embargo, debido a los problemas médico-legales que puede ocasionar, es reportado en menor frecuencia. Los síntomas suelen ser poco específicos y el diagnóstico se basa en estudios de imagen. El tratamiento más adecuado es la intervención quirúrgica para su remoción. El término “textiloma” se refiere a un cuerpo de tela dejado involuntariamente en el paciente durante la cirugía y a las reacciones secundarias que perpetúan su presencia en el cuerpo. La sospecha clínica es de suma importancia para el correcto diagnóstico de esta entidad. Presentamos el caso de un masculino de 53 años de edad, con antecedente de colecistectomía abierta hace 9 años por cuadro agudo de colecistitis. Inicia su padecimiento con dolor abdominal en epigastrio tipo cólico, agravándose con dolor en hipocondrio e incapacidad para canalizar gases, además de intolerancia a la vía oral. Se encontró paciente orientado, mal estado de hidratación, peristalsis disminuida, dolor a la palpación en hipocondrio derecho con masa en el mismo. Laboratorio sin anormalidades, se le realizaron estudios de gabinete reportando una imagen sugestiva de un textiloma, se le realiza laparotomía exploratoria la cual reveló tumor con cápsula fibrosa adherido al colon e hígado. El reporte histopatológico fue compatible con cuerpo extraño. El paciente evolucionó satisfactoriamente

Modification of the mean free path of very high-energy photons due to a relativistic deformed kinematics

Ultra-high-energy physics is about to enter a new era thanks to the impressive results of experiments such as the Large High Altitude Air Shower Observatory, detecting photons of up to 1.4×10^15 eV (PeV scale). These new results could be used to test deviations with respect to special relativity. While this has been already explored within the approach of Lorentz Invariance Violation theories, in this work we consider, for the first time, modifications due to a relativistic deformed kinematics (which appear in Doubly Special Relativity, or DSR, theories). In particular, we study the mean free path of very high-energy photons due to electron-positron pair creation when interacting with low-energy photons of the cosmic microwave background. Depending on the energy scale of the relativistic deformed kinematics, present (or near future) experiments can be sensitive enough to be able to identify deviations from special relativity

Physics of the universe transparency in a deformed kinematics

We present a first study of the possible effects of a relativistic deformation of special relativity in the recent observations of very high-energy gamma rays by the LHAASO experiment, which has opened a new phenomenological window to study deformations in the kinematics of special relativity. Our analysis of the interaction of high-energy photons with the CMB background complements theoretical studies based on Lorentz invariance violation scenarios, while making predictions that would allow one to distinguish between a violation and a deformation of the symmetries of special relativity

Influence of body mass and skinfolds on skin temperature through infrared thermography

Thermal response of skin temperature (Tsk) has been studied during exercise and immediately after (Merla, 2010). However, more studies about the influence of exercise on Tsk through the time are required to understand the impact of physical activity on thermoregulatory system and metabolis

Modeling and behavior of the simulation of electric propagation during deep brain stimulation

Deep brain stimulation (DBS) is an effective treatment for Parkinson's disease. In the literature, there are a wide variety of mathematical and computational models to describe electric propagation during DBS; however unfortunately, there is no clarity about the reasons that justify the use of a specific model. In this work, we present a detailed mathematical formulation of the DBS electric propagation that supports the use of a model based on the Laplace Equation. Moreover, we performed DBS simulations for several geometrical models of the brain in order to determine whether geometry size, shape and ground location influence electric stimulation prediction by using the Finite Element Method (FEM). Theoretical and experimental analysis show, firstly, that under the correct assumptions, the Laplace equation is a suitable alternative to describe the electric propagation, and secondly, that geometrical structure, size and grounding of the head volume affect the magnitude of the electric potential, particularly for monopolar stimulation. Results show that, for monopolar stimulation, basic and more realistic models can differ more than 2900%

Hypothesis-oriented food patterns and incidence of hypertension: 6-year follow-up of the SUN (Seguimiento Universidad de Navarra) prospective cohort

Objective To study the association between adherence to several a priori-defined healthy food patterns and the risk of hypertension. Design Prospective, multipurpose, dynamic cohort study (recruitment permanently open). We followed up 10 800 men and women (all of them university graduates), who were initially free of hypertension, for a variable period (range 2–6 years, median 4·6 years). During follow-up, 640 participants reported a new medical diagnosis of hypertension. Baseline diet was assessed using a validated 136-item FFQ. Validated information about non-dietary potential confounders was also gathered. We calculated adherence to fifteen different hypothesis-oriented food patterns and assessed the association between each of them and incident hypertension using multivariable Cox models. Setting The SUN (Seguimiento Universidad de Navarra – University of Navarra Follow-up) Project, Spain. Subjects Participants recruited to the SUN cohort before October 2005 were eligible for inclusion; after excluding those with self-reported hypertension or CVD at baseline, or with extreme total energy intake, data of 10 800 were analysed. Results Higher adherence to the DASH (Dietary Approaches to Stop Hypertension) diet (range of the score: 0 to 5) was significantly associated with a lower risk for developing hypertension (P for trend = 0·02). The other food patterns showed no significant association with incident hypertension. Conclusions Our results support a long-term protection of the DASH diet against the incidence of hypertension, but we found no evidence of a similar inverse association with hypertension for any other a priori-defined healthy food pattern