BTZ Solutions on Codimension-2 Braneworlds

We consider five-dimensional gravity with a Gauss-Bonnet term in the bulk and an induced gravity term on a 2-brane of codimension-2. We show that this system admits BTZ-like black holes on the 2-brane which are extended into the bulk with regular horizons.Comment: 6 pages. Talk given at Recent Developments in Gravity (NEB XIII), Thessaloniki, Greece, June 4-6, 2008

Quasinormal modes and thermodynamical aspects of the 3D Lifshitz black hole

We consider scalar and spinorial perturbations on a background described by a $z=3$ three-dimensional Lifshitz black hole. We obtained the corresponding quasinormal modes which perfectly agree with the analytical result for the quasinormal frequency in the scalar case. The numerical results for the spinorial perturbations reinforce our conclusion on the stability of the model under these perturbations. We also calculate the area spectrum, which prove to be equally spaced, as an application of our results.Comment: 8 pages, 5 figures. Prepared for "Recent Developments in Gravity (NEB XV)", Chania, Greece, 20-23 June 201

Instability of the Time Dependent Horava-Witten Model

We consider scalar perturbations in the time-dependent Ho\u{r}ava-Witten Model in order to probe its stability. We show that during the non-singular epoque the model evolves without instabilities until it encounters the curvature singularity where a big crunch is supposed to occur. We compute the frequencies of the scalar field oscillation during the stable period and show how the oscillations can be used to prove the presence of such a singularity.Comment: 12 pages, 4 figures. References added. Some comments clarified. Accepted in Phys. Rev.

Shortcuts in a Nonlinear Dynamical Braneworld in Six Dimensions

We consider a dynamical brane world in a six-dimensional spacetime containing a singularity. Using the Israel conditions we study the motion of a 4-brane embedded in this setup. We analyse the brane behaviour when its position is perturbed about a fixed point and solve the full nonlinear dynamics in the several possible scenarios. We also investigate the possible gravitational shortcuts and calculate the delay between graviton and photon signals and the ratio of the corresponding subtended horizons.Comment: 26 pages, 9 figures. References and discussion added. Title changed to match the version accepted in Class. and Quant. Gra

Enfermedad por reflujo gastroesofágico. Detalles nuevos de una enfermedad vieja

Disease caused by gastro esophageal reflux is a pathology of great prevalence in the world. Its treatment is very expensive and requires a deep knowledge of physiopathological aspects to understand the clinic problems and make an appropriate management. Among the mainaspects of physiopathology, the spontaneous relaxations of lower esophageal sphincter are an important morbidity cause like other aspects included in this review. Within the clinical aspect, it is fundamental the erosive and non-erosive classification, in addition to the characterizationbetween atypical and typical symptoms in order to implement a treatment according to patient's needs.La enfermedad por reflujo gastroesofágico representa una patología de gran prevalencia en el mundo, esta genera altos costos económicos y requiere un estricto conocimiento de aspectos fisiopatológicos para entender sus problemas clínicos y poder realizar un adecuado manejo. Dentro de los principales aspectos de la fisiopatología las relajaciones espontáneas del esfínter esofágico inferior representan una causa importante de morbilidad al igual que otros aspectos tratados en esta revisión. En el aspecto clínico es fundamental la clasificación en erosivo y no erosivo además de la caracterización entre síntomas atípicos y típicos para implementar un tratamiento acorde a las necesidades del paciente

Stability Analysis and Area Spectrum of 3-Dimensional Lifshitz Black Holes

In this work, we probe the stability of a $z=3$ three-dimensional Lifshitz black hole by using scalar and spinorial perturbations. We found an analytical expression for the quasinormal frequencies of the scalar probe field, which perfectly agree with the behavior of the quasinormal modes obtained numerically. The results for the numerical analysis of the spinorial perturbations reinforce the conclusion of the scalar analysis, i.e., the model is stable under scalar and spinor perturbations. As an application we found the area spectrum of the Lifshitz black hole, which turns out to be equally spaced.Comment: 23 pages, 6 figures. References added. Version to appear in Phys. Rev.

Perturbations of Gauss-Bonnet Black Strings in Codimension-2 Braneworlds

We derive the Lichnerowicz equation in the presence of the Gauss-Bonnet term. Using the modified Lichnerowicz equation we study the metric perturbations of Gauss-Bonnet black strings in Codimension-2 Braneworlds.Comment: 26 pages, no figures, clarifying comments and one reference added, to be published in JHE

Hemorragia digestiva de origen oscuro: “una causa no sospechada”

Obscure gastrointestinal bleeding is found in 5-10% of cases of intestinal bleeding, recurring in 50% of cases. It is caused by various aetiologies which can make diagnosis a challenge, requiring various endoscopic procedures. Among the unusual causes are nematode intestinal parasites, prevalent in tropical areas and developing countries. The study presents the case of a patient with recurrent obscure gastrointestinal bleeding triggered by Ascaris lumbricoides, who required various hospitalisations, blood transfusions and a set of endoscopic procedures before the aetiological diagnosis and subsequent treatment. This demonstrates the necessity to know the true cost-effectiveness of preventive parasite control in all patients with gastrointestinal bleeding and negative results for the first endoscopic evaluation, taking the high prevalence of nematodes in our country into account.La hemorragia digestiva de origen oscuro se presenta en el 5 -10% del sangrado intestinal, con persistencia o recurrencia en el 50%, de los casos. Es ocasionado por varías etiologías, generando un desafío diagnóstico que requiere la realización de varios procedimientos endoscópicos. Entre las causas inusuales se encuentran las parasitosis intestinales por nematodos, siendo prevalentes en zonas tropicales y países en vía de desarrollo. Presentamos el caso de una paciente con hemorragia digestiva de origen oscuro manifiesto recurrente desencadenado por Ascaris lumbricoides, quien requirió varias hospitalizaciones, soporte transfusional y realización de un set de procedimientos endoscópicos previo al diagnóstico etiológico y posterior tratamiento planteando la necesidad de conocer la real costo efectividad de la desparasitación profiláctica en todo paciente con hemorragia intestinal y primera evaluación endoscópica estándar negativa, teniendo en cuenta la alta prevalencia de nematodos en nuestro país