MODELLING OF HYDRODYNAMICS AROUND AN IMPERMEABLE BREAKWATER: COMPARISON BETWEEN PHYSICAL AND SPH NUMERICAL MODELING

This work presents the new developments and the validation of a Smoothed Particle Hydrodynamics (SPH) numerical model used in the National Laboratory of Civil Engineering (Laboratório Nacional de Engenharia Civil - LNEC) for studies in coastal engineering processes. Although the model requires a high CPU time, it proved to be very promising in the simulation of complex flows, such as the wave-structure interaction and the wave breaking phenomenon. For the SPH model validation, physical modeling tests were performed in one LNEC’s flume to study the interaction between an impermeable structure and an incident regular wave. The comparison between numerical and experimental results, i.e. free surface elevation, overtopping volume and pressure, shows the good accuracy of the SPH model to reproduce the various phenomena involving on the wave propagation and interaction with the structure, namely the wave breaking, the wave overtopping and the pressure field on the structure

Modified Gravity on the Brane and Dark Energy

We analyze the dynamics of an AdS5 braneworld with matter fields when gravity is allowed to deviate from the Einstein form on the brane. We consider exact 5-dimensional warped solutions which are associated with conformal bulk fields of weight -4 and describe on the brane the following three dynamics: those of inhomogeneous dust, of generalized dark radiation, and of homogeneous polytropic dark energy. We show that, with modified gravity on the brane, the existence of such dynamical geometries requires the presence of non-conformal matter fields confined to the brane.Comment: Revised version published in Gen. Rel. Grav. Typos corrected, updated reference and some remarks added for clarity. 11 pages, latex, no figure

Analytical results for a Bessel function times Legendre polynomials class integrals

When treating problems of vector diffraction in electromagnetic theory, the evaluation of the integral involving Bessel and associated Legendre functions is necessary. Here we present the analytical result for this integral that will make unnecessary numerical quadrature techniques or localized approximations. The solution is presented using the properties of the Bessel and associated Legendre functions.Comment: 4 page

The mass of the graviton and the cosmological constant

We show that the graviton acquires a mass in a de Sitter background given by $m_{g}^{2}=-{2/3}\Lambda.$ This is precisely the fine-tuning value required for the perturbed gravitational field to mantain its two degrees of freedom.Comment: Title changed and few details added, without any changes in the conclusio

Cervical spondylodiscitis in an infant

An Esp Pediatr. 2000 Apr;52(4):398-400. [Cervical spondylodiscitis in an infant] [Article in Spanish] Oliveira T, Barbosa C, Neves E, Guimarães A, Sexto C, Cruz R. Servicio de Pediatría, Hospital Maria Pia, Porto, Portugal. Abstract Spondylitis in childhood is rare, presenting a great variety of symptoms that are related to the child s age and to the site of the inflammatory process. We present the case of a nine-month-old infant, who presented to the emergency department with a torticollis of six weeks evolution. The diagnosis of spondylitis (C6-C7) was confirmed by MRI. Intravenous antibiotic therapy was administered. The patient showed complete regression of symptoms and imaging tests were normal. The rarity of this disease in patients in this age group, as well as the site and form of presentation are emphasised as is the importance of diagnosing this disease to prevent permanent neurological injuries or bone deformities. PMID: 11003937 [PubMed - indexed for MEDLINE