On Effective Spacetime Dimension in the Ho\v{r}ava-Lifshitz Gravity

In this manuscript we explicitly compute the effective dimension of spacetime in some backgrounds of Ho\v{r}ava-Lifshitz (H-L) gravity. For all the cases considered, the results are compatible with a dimensional reduction of the spacetime to $d+1=2$, at high energies (ultraviolet limit), which is confirmed by other quantum gravity approaches, as well as to $d+1=4$, at low energies (infrared limit). This is obtained by computing the free energy of massless scalar and gauge fields. We find that the only effect of the background is to change the proportionality constant between the internal energy and temperature. Firstly, we consider both the non-perturbative and perturbative models involving the matter action, without gravitational sources but with manifest time and space symmetry breaking, in order to calculate modifications in the Stephan-Boltzmann law. When gravity is taken into account, we assume a scenario in which there is a spherical source with mass $M$ and radius $R$ in thermal equilibrium with radiation, and consider the static and spherically symmetric solution of the H-L theory found by Kehagias-Sfetsos (K-S), in the weak and strong field approximations. As byproducts, for the weak field regime, we used the current uncertainty of the solar radiance measurements to establish a constraint on the $\omega$ free parameter of the K-S solution. We also calculate the corrections, due to gravity, to the recently predicted attractive force that black bodies exert on nearby neutral atoms and molecules.Comment: references adde

Relativistic Landau Levels in the Rotating Cosmic String Spacetime

In the spacetime induced by a rotating cosmic string we compute the energy levels of a massive spinless particle coupled covariantly to a homogeneous magnetic field parallel to the string. Afterwards, we consider the addition of a scalar potential with a Coulomb-type and a linear confining term and completely solve the Klein-Gordon equations for each configuration. Finally, assuming rigid-wall boundary conditions, we find the Landau levels when the linear defect is itself magnetized. Remarkably, our analysis reveals that the Landau quantization occurs even in the absence of gauge fields provided the string is endowed with spin.Comment: Writing and grammar revised. References added. 14 pages, no figures. To appear in European Phys. J.

Fatores de Risco Associados à Mortalidade Neonatal em Pacientes Internados no Serviço de Neonatologia do Hospital Infantil Nossa Senhora da Glória/ Vitória-es Entre 2002/2005.

Este estudo identifica os fatores de risco para o óbito, na unidade de cuidados neonatais do Hospital Infantil Nossa Senhora da Glória /Vitória E.S, no período de 2002 a 2005, através de estudo caso-controle pareado por ano de internação e idade gestacional. As variáveis estudadas foram agrupadas da seguinte forma: maternas, da assistência pré-natal e perinatal, referentes aos recém-nascidos e da assistência na internação hospitalar. Os dados de 55 casos (óbitos em menores de 28 dias) e 203 controles (sobreviventes ao mesmo período) foram submetidos aos testes χ 2, teste t de Student, calculadas as razões de chance (Odds Ratio) com intervalo de confiança de 95% e regressão logística. O tempo de trabalho de parto menor que 24h foi fator de proteção (OR = 0,38 IC = 0,16 - 0,93), a necessidade de suporte de drogas vasoativas (OR = 18,43 IC = 6,08 62,54) e peso ao nascer - categoria 500g a 1.000g (OR = 5,94 IC = 2,27 16,68) foram fatores de risco. Os resultados obtidos constituem uma ferramenta importante no planejamento de intervenções mais adequadas em unidades de cuidados neonatais, bem como na atenção básica à saúde