Unconventional cosmology on the (thick) brane

We consider the cosmology of a thick codimension 1 brane. We obtain the matching conditions leading to the cosmological evolution equations and show that when one includes matter with a pressure component along the extra dimension in the brane energy-momentum tensor, the cosmology is of non-standard type. In particular one can get acceleration when a dust of non-relativistic matter particles is the only source for the (modified) Friedman equation. Our equations would seem to violate the conservation of energy-momentum from a 4D perspective, but in 5D the energy-momentum is conserved. One could write down an effective conserved 4D energy-momentum tensor attaching a ``dark energy'' component to the energy-momentum tensor of matter that has pressure along the extra dimension. This extra component could, on a cosmological scale, be interpreted as matter-coupled quintessence. We comment on the effective 4D description of this effect in terms of the time evolution of a scalar field (the 5D radion) coupled to this kind of matter.Comment: 9 pages, v2. eq.(17) corrected, comments on effective theory change

Effect of silver on the phase transition and wettability of titanium oxide films

The effect of silver on the phase transition and microstructure of titanium oxide films grown by pulsed cathodic arc had been investigated by XRD, SEM and Raman spectroscopy. Following successive thermal annealing up to 1000 °C, microstructural analysis of annealed Ag-TiO2 films reveals that the incorporation of Ag nanoparticles strongly affects the transition temperature from the initial metastable amorphous phase to anatase and stable rutile phase. An increase of silver content into TiO2 matrix inhibits the amorphous to anatase phase transition, raising its temperature boundary and, simultaneously reduces the transition temperature to promote rutile structure at lower value of 600 °C. The results are interpreted in terms of the steric effects produced by agglomeration of Ag atoms into larger clusters following annealing which hinders diffusion of Ti and O ions for anatase formation and constrains the volume available for the anatase lattice, thus disrupting its structure to form rutile phase. The effect of silver on the optical and wetting properties of TiO2 was evaluated to demonstrate its improved photocatalytic performance

A quantum model of Schwarzschild black hole evaporation

We construct a one-loop effective metric describing the evaporation phase of a Schwarzschild black hole in a spherically symmetric null-dust model. This is achieved by quantising the Vaidya solution and by chosing a time dependent quantum state. This state describes a black hole which is initially in thermal equilibrium and then the equilibrium is switched off, so that the black hole starts to evaporate, shrinking to a zero radius in a finite proper time. The naked singularity appears, and the Hawking flux diverges at the end-point. However, a static metric can be imposed in the future of the end-point. Although this end-state metric cannot be determined within our construction, we show that it cannot be a flat metric

Immunity and simplicity in relativizations of probabilistic complexity classes

The existence of immune and simple sets in relativizations of the probabilistic polynomial time bounded classes is studied. Some techniques previously used to show similar results for relativizations of P and NP are adapted to the probabilistic classes. Using these results, an exhaustive settling of all possible strong separations among these relativized classes is obtained.On étudie les relativisations des classes de complexité probabiliste polynômiale. On adapte aux classes probabilistes des techniques déjà utilisées pour établir des résultats similaires pour les relativisations de P et NP. On obtient à partir de ces résultats une classification de toutes les propriétés de séparation forte pour ces classes relativisées.Peer ReviewedPostprint (published version

Diffeomorphisms, Noether Charges and Canonical Formalism in 2D Dilaton Gravity

We carry out a parallel study of the covariant phase space and the conservation laws of local symmetries in two-dimensional dilaton gravity. Our analysis is based on the fact that the Lagrangian can be brought to a form that vanishes on-shell giving rise to a well-defined covariant potential for the symplectic current. We explicitly compute the symplectic structure and its potential and show that the requirement to be finite and independent of the Cauchy surface restricts the asymptotic symmetries.Comment: 14 pages, latex with psfig macro, one figur

Hawking radiation by Kerr black holes and conformal symmetry

The exponential blueshift associated with the event horizon of a black hole makes conformal symmetry play a fundamental role in accounting for its thermal properties. Using a derivation based on two-point functions, we show that the spectrum of thermal radiation of scalar particles by Kerr (and Schwarzschild) black holes can be explicitly derived on the basis of a $2$-dimensional conformal symmetry arising in the wave equation near the horizon. This result reinforces the recently conjectured relation between Kerr geometry and a $2$-dimensional conformal field theory.Comment: Version published in Phys. Rev. Let

Osteomielitis vertebral cervical como complicación de cirugía faríngea: a propósito de un caso

Se presenta un caso de un a enferma de 59 años, diabética, afecta de un a osteomielitis vertebral cervical por Candida Albicans. La vía de infección fué la persistencia durante varios meses de unos tutores, colocados tras la resección de un a estenosis nasofaríngea , que impactaban sobre la cara anterior de la vértebra C3. El desarrollo insidioso y la ausencia de un cuadro clínico específico fué la causa del retraso diagnóstico.A 5 9 yea r ol d woma n wit h diabete s mellitu s presente d a cervica l vertebra l osteomyelitis du e t o Candid a Albicans. Th e chroni c implantatio n o f dilatio n tube s followin g th e resectio n o f a nasopharyngea l stenosis wa s th e mod e o f infection . Th e insidiou s an d prolonge d onse t an d n o specifica l clinica l pictur e wer e t h e caus e o f dela y i n th e diagnosi

El efecto socializador del medio televisivo en jóvenes. Influencia de las conductas de gestión del conflicto mostradas por personajes de series de ficción

Clearly the influence of television in society, being the study of violence and its impact on children and young people the subject of most investigations. How to manage conflict becomes a variable indicative of violent behavior, therefore, this work has been an analysis of the styles of managing conflicts of characters in the television series most viewed by young people, being results based on the sex of the characters analyzed, and associating these different styles of behaviors and attitudes that young men and women assigned to.Resulta evidente la influencia del medio televisivo en la sociedad, siendo el estudio de la violencia y sus consecuencias en niños y jóvenes el objeto de la mayoría de las investigaciones al respecto. El modo de gestionar los conflictos se convierte en una variable indicativa de conductas violentas, por ello, este trabajo ha realizado un análisis de los estilos de gestionar conflictos de personajes de las series televisivas más vistas por jóvenes, hallándose resultados en función del sexo de los personajes analizados, y asociándose estas diferencias de estilos a conductas y actitudes que los jóvenes asignan a hombres o mujeres

On The Reduced Canonical Quantization Of The Induced 2D-Gravity

The quantization of the induced 2d-gravity on a compact spatial section is carried out in three different ways. In the three approaches the supermomentum constraint is solved at the classical level but they differ in the way the hamiltonian constraint is imposed. We compare these approaches establishing an isomorphism between the resulting Hilbert spaces.Comment: 17 pages, plain LaTeX. FTUV/93-15, IFIC/93-10, Imperial-TP/93-94/1

Producción y distribución de los quesos artesanos en Andalucía occidental

En el presente trabajo se presentan los resultados obtenidos de un estudio sobre la producción y la distribución de quesos artesanos, realizado en 4 comarcas de Andalucía occidental: Sierra de Cádiz, Sierra de Aracena, Valle del Guadalhorce y Valle de los Pedroches. La leche de cabra es la que se transforma en mayor cantidad con casi un 80 %, seguida de la de vaca y la de oveja. Los canales de comercialización suelen ser circuitos de radio corto, distribuyendo los productos principalmente en tiendas o supermercados. Para finalizar se exponen algunas acciones de investigación, desarrollo y formación fundamentalmente dirigidas a mejorar el conocimiento de parámetros que afectan a la calidad, potenciar su singularidad (recetas tradicionales) y facilitar su comercialización a través de estudios de percepción de la calidad y hábitos de consumo