Search results for "palatini"
showing 7 items of 7 documents
Brane-world and loop cosmology from a gravity–matter coupling perspective
2015
We show that the effective brane-world and the loop quantum cosmology background expansion histories can be reproduced from a modified gravity perspective in terms of an $f(R)$ gravity action plus a $g(R)$ term non-minimally coupled with the matter Lagrangian. The reconstruction algorithm that we provide depends on a free function of the matter density that must be specified in each case and allows to obtain analytical solutions always. In the simplest cases, the function $f(R)$ is quadratic in the Ricci scalar, $R$, whereas $g(R)$ is linear. Our approach is compared with recent results in the literature. We show that working in the Palatini formalism there is no need to impose any constrai…
Dynamical generation of wormholes with charged fluids in quadratic Palatini gravity
2014
The dynamical generation of wormholes within an extension of General Relativity (GR) containing (Planck's scale-suppressed) Ricci-squared terms is considered. The theory is formulated assuming the metric and connection to be independent (Palatini formalism) and is probed using a charged null fluid as a matter source. This has the following effect: starting from Minkowski space, when the flux is active the metric becomes a charged Vaidya-type one, and once the flux is switched off the metric settles down into a static configuration such that far from the Planck scale the geometry is virtually indistinguishable from that of the standard Reissner-Nordstr\"om solution of GR. However, the innerm…
Planck scale physics and topology change through an exactly solvable model
2014
We consider the collapse of a charged radiation fluid in a Planck-suppressed quadratic extension of General Relativity (GR) formulated à la Palatini. We obtain exact analytical solutions that extend the charged Vaidya-type solution of GR, which allows to explore in detail new physics at the Planck scale. Starting from Minkowski space, we find that the collapsing fluid generates wormholes supported by the electric field. We discuss the relevance of our findings in relation to the quantum foam structure of space–time and the meaning of curvature divergences in this theory.
Objective tinnitus secondary to palatal tremor: Two case reports and brief literature review.
2021
Abstract Objective tinnitus is defined as a type of tinnitus perceived by both the patient and external observer. This paper presents two cases of objective tinnitus related to palatal tremor, along with a literature review. Palatal tremor is a condition characterized by soft palate involuntary contractions. Two types of palatal tremor have been described: symptomatic palatal tremor and essential palatal tremor, with different clinical manifestations. Diagnostic workup is based on medical history and physical examination, including direct oropharynx exploration and cavum visualization through nasopharyngoscopy. Brain MRI is mandatory in all cases. If a secondary origin is suspected, additio…
Black Holes, Geons, and Singularities in Metric-Affine Gravity
2016
Uno de los problemas abiertos en la descripción de la gravedad es la existencia de singularidades. Las geometrías singulares se caracterizan por geodésicas incompletas, lo que físicamente se corresponde con observadores que desaparecen del espacio-tiempo, o que aparecen de la nada. Múltiples extensiones de la Relatividad General tratan de resolver este problema de algún modo. Por ello, en esta tesis estudio modificaciones al Lagrangiano de Relatividad General, tales como gravedad cuadrática y gravedad de Born-Infeld, en el formalismo Métrico-Afín. En este formalismo, la conexión (de la cual se derivan los tensores de curvatura) se considera independiente de la métrica, y permitimos que sea …
Rehabilitación del maxilar superior con atrofia severa horizontal utilizando implantes dentales palatinizados.
2016
Objetivo: Evaluar las condiciones de los tejidos blandos y la pérdida de hueso alrededor de los implantes palatinizados en maxilares con severa atrofia horizontal, rehabilitados con prótesis fija de arco completo y compararlos con los implantes convencionales centrados en la cresta ósea de maxilares no atróficos tras un periodo mínimo de 5 años de seguimiento. Material y método: Se realizó un estudio retrospectivo clínico y controlado sobre pacientes que fueron rehabilitados con prótesis fija de arcada completa sobre implantes dentales en el maxilar y con un seguimiento mínimo de 5 años después de la carga del implante. Los pacientes se dividieron en 2 grupos: pacientes con maxilar clase IV…
Tensor tympani muscle: strange chewing muscle
2007
This work seeks to alert medical and odontological staff to understanding and using interdisciplinary handling for detecting different pathologies’ common otic symptoms. It offers better tools for this shared symptomatology during therapy’s conservative phase. Tensor tympani muscle physiology and function in the middle ear have been veiled, even when their dysfunction and anatomical relationships may explain a group of confused otic symptoms during conventional clinical evaluation. Middle ear muscles share a common embryological and functional origin with chewing and facial muscles. This article emphasizes that these muscles share a functional neurological and anatomical dimension with the …