Network of recurrent events for the Olami-Feder-Christensen model

We numerically study the dynamics of a discrete spring-block model introduced by Olami, Feder and Christensen (OFC) to mimic earthquakes and investigate to which extent this simple model is able to reproduce the observed spatiotemporal clustering of seismicty. Following a recently proposed method to characterize such clustering by networks of recurrent events [Geophys. Res. Lett. {\bf 33}, L1304, 2006], we find that for synthetic catalogs generated by the OFC model these networks have many non-trivial statistical properties. This includes characteristic degree distributions -- very similar to what has been observed for real seismicity. There are, however, also significant differences between the OFC model and earthquake catalogs indicating that this simple model is insufficient to account for certain aspects of the spatiotemporal clustering of seismicity.Comment: 11 pages, 16 figure

Herdabilidade e correlações genótipicas entre caracteres de folhagem e sistema radicular em famílias de cenoura, cultivar Brasília.

Made available in DSpace on 2011-04-09T16:13:20Z (GMT). No. of bitstreams: 1 alvesherdabilidade.pdf: 597318 bytes, checksum: a4bcf3b38f590ccdb33384379d85f6d5 (MD5) Previous issue date: 2006-11-1

Symmetry aspects of fermions coupled to torsion and electromagnetic fields

We study and explore the symmetry properties of fermions coupled to dynamical torsion and electromagnetic fields. The stability of the theory upon radiative corrections as well as the presence of anomalies are investigated.Comment: 9 pages, LaTe

Renormalization Ambiguities and Conformal Anomaly in Metric-Scalar Backgrounds

We analyze the problem of the existing ambiguities in the conformal anomaly in theories with external scalar field in curved backgrounds. In particular, we consider the anomaly of self-interacting massive scalar field theory and of Yukawa model in the massless conformal limit. In all cases the ambiguities are related to finite renormalizations of a local non-minimal terms in the effective action. We point out the generic nature of this phenomenon and provide a general method to identify the theories where such an ambiguity can arise.Comment: RevTeX, 10 pages, no figures. Small comment and two references added. Accepted for publication in Physical Review

Higher Derivative Quantum Gravity with Gauss-Bonnet Term

Higher derivative theory is one of the important models of quantum gravity, renormalizable and asymptotically free within the standard perturbative approach. We consider the $4-\epsilon$ renormalization group for this theory, an approach which proved fruitful in $2-\epsilon$ models. A consistent formulation in dimension $n=4-\epsilon$ requires taking quantum effects of the topological term into account, hence we perform calculation which is more general than the ones done before. In the special $n=4$ case we confirm a known result by Fradkin-Tseytlin and Avramidi-Barvinsky, while contributions from topological term do cancel. In the more general case of $4-\epsilon$ renormalization group equations there is an extensive ambiguity related to gauge-fixing dependence. As a result, physical interpretation of these equations is not universal unlike we treat $\epsilon$ as a small parameter. In the sector of essential couplings one can find a number of new fixed points, some of them have no analogs in the $n=4$ case.Comment: LaTeX file, 30 pages, 5 figures. Several misprints in the intermediate expressions correcte

Biochemical assessment of oxidative stress by the use of açai (Euterpe oleracea Martius) gel in physically active individuals.

Abstract The relation between oxidative stress and inflammation induced by diseases and exercise has increased the interest in the benefits of antioxidant supplements in the improvement of health and physical and mental performance. The aim of this study was to evaluate the effectiveness of açai gel in reducing oxidative stress in individuals engaged in physical activities as well as their acceptance. Sensory evaluation was performed to determine its acceptability and the biochemical parameters related to immune profile and biomarkers of muscle, liver and oxidative stress, with and without the use of gel were evaluated. The appearance, sweetness and overall impression of the açai gel were considered good. It was observed a significant increase in CK enzyme, without the gel as well as the oxidative stress biomarkers, it was observed that the MDA (with and without gel) a significant increase (p < 0.05). Through biochemical evaluation, it is concluded that the gel provided protection for some of parameters studied, since it modulated the immunological parameter reducing the lymphocyte activity and muscular stress. However, more studies must be carried out with a larger number of individuals to confirm the gel functionality

Modelling the Recoherence of Mesoscopic Superpositions in Dissipative Environments

A model is presented to describe the recently proposed experiment (J. Raimond, M. Brune and S. Haroche Phys. Rev. Lett {\bf 79}, 1964 (1997)) where a mesoscopic superposition of radiation states is prepared in a high-Q cavity which is coupled to a similar resonator. The dynamical coherence loss of such state in the absence of dissipation is reversible and can in principle be observed. We show how this picture is modified due to the presence of the environmental couplings. Analytical expressions for the experimental conditional probabilities and the linear entropy are given. We conclude that the phenomenon can still be observed provided the ratio between the damping constant and the inter-cavities coupling does not exceed about a few percent. This observation is favored for superpositions of states with large overlap.Comment: 13 pages, 6 figure

The dissipation of the system and the atom in two-photon Jaynes-Cummings model with degenerate atomic levels

The method of perturbative expansion of master equation is employed to study the dissipative properties of system and of atom in the two-photon Jaynes-Cummings model (JCM) with degenerate atomic levels. The numerical results show that the degeneracy of atomic levels prolongs the period of entanglement between the atom and the field. The asymptotic value of atomic linear entropy is apparently increased by the degeneration. The amplitude of local entanglement and disentanglement is suppressed. The better the initial coherence property of the degenerate atom, the larger the coherence loss.Comment: 11 pages, 4 figure

Propagating Torsion in 3D-Gravity and Dynamical Mass Generation

In this paper, fermions are minimally coupled to 3D-gravity where a dynamical torsion is introduced. A Kalb-Ramond field is non-minimally coupled to these fermions in a gauge-invariant way. We show that a 1-loop mass generation mechanism takes place for both the 2-form gauge field and the torsion. As for the fermions, no mass is dynamically generated: at 1-loop, there is only a mass shift proportional to the Yukawa coupling whenever the fermions have a non-vanishing tree-level mass.Comment: 13 pages, latex file, no figures, some corrections adde