A low-power/low-voltage CMOS wireless interface at 5.7 GHz with dry electrodes for cognitive networks

This paper describes a low-power/low-voltage CMOS wireless interface (CMOS-WiI) at 5.7 GHz with dry electrodes for congnitive networks. The electrodes are 4 x 4 microtip arrays and acquire electroencephalogram (EEG) signals in key- points for processing. The CMOS-WiI was fabricated in a UMC 0.18 µm RF CMOS process and its total power consumption is 23mW with a voltage-supply of only 1.5 V. The carrier frequency is digitally selectable and it can be one of 16 possible values in the range 5.42–5.83 GHz, with 27.12 MHz steps. These multiple carriers allow a better spectrum allocation as well as the acquisition, processing and transmission of high-quality EEG signals from 16 electrode arrays. The microtips array was fabricated through bulk micromachining of a -type silicon substrate in a potassium hydroxide solution and avoids long subject preparations for EEG data acquisition. The reactive sputtering of iridium dioxide (IrO) on the surface of the array guarantees its biocompatibility. The fabrication process was trimmed in a way that each microtip presents solid angles of 54.7 , a width in the range 150–200 µm, a height of 100–200 µm, and a microtip interspacing of 2 µm. The microtips array coated with IrO together with the CMOS-WiI permit the remote monitoring of EEG signals from freely-moving subjects

Geometric approach to chaos in the classical dynamics of abelian lattice gauge theory

A Riemannian geometrization of dynamics is used to study chaoticity in the classical Hamiltonian dynamics of a U(1) lattice gauge theory. This approach allows one to obtain analytical estimates of the largest Lyapunov exponent in terms of time averages of geometric quantities. These estimates are compared with the results of numerical simulations, and turn out to be very close to the values extrapolated for very large lattice sizes even when the geometric quantities are computed using small lattices. The scaling of the Lyapunov exponent with the energy density is found to be well described by a quadratic power law.Comment: REVTeX, 9 pages, 4 PostScript figures include

Anti-de Sitter curvature radius constrained by quasars in brane-world scenarios

This paper is intended to investigate the luminosity due to accretion of gas in supermassive black holes (SMBHs) in the center of quasars, using a brane-world scenario naturally endowed with extra dimensions, whereon theories formulated introduce corrections in the field equations at high energies. SMBHs possess the necessary highly energetic environment for the introduction of these corrections, which are shown to produce small deviations in all SMBH properties and, consequentely, corrections in the accretion theory that supports quasars radiative processes. The radiative flux observed from quasars indicates these deviations, from which the magnitude of the AdS$_5$ bulk curvature radius, and consequently the extra dimension compactification radius is estimated.Comment: 11 pages, RevTeX, Eq.(2) and (3) expanded, and comments thereon update

Características gerais de sistemas de produção realizados por produtores de caprinos leiteiros associados às cooperativas de Jussara e Valente na Bahia.

Este trabalho teve como objetivo caracterizar os sistemas de produçao aplicados a caprinos leiteiros nas microrregioes de Jussara e Valente na Bahia. Utilizaram-se dados retirados de entrevistas com 45 produtores que utilizavam o leite para consumo proprio ou venda. As propriedades possuiam, em media, 55 hectares. Em 42% das propriedades, os animais se alimentavam em areas de fundo de pasto. 0 sistema de produçao animal pode ser caracterizado como urn sistema misto. A media de produçao obtida foi de 8,5 litros ao dia e a media da produçao comercializada mensalmente foi de 409 litros. Apenas 2 produtores fabricavam queijo e apenas 2 produtores fabricavam doce de leite.Grande parte dos dados obtidos apresentou altos valores de coeficiente de variaçao, refletindo a grande diversidade dos sistemas de produçao e comercializaçao

Hamiltonian dynamics of the two-dimensional lattice phi^4 model

The Hamiltonian dynamics of the classical $\phi^4$ model on a two-dimensional square lattice is investigated by means of numerical simulations. The macroscopic observables are computed as time averages. The results clearly reveal the presence of the continuous phase transition at a finite energy density and are consistent both qualitatively and quantitatively with the predictions of equilibrium statistical mechanics. The Hamiltonian microscopic dynamics also exhibits critical slowing down close to the transition. Moreover, the relationship between chaos and the phase transition is considered, and interpreted in the light of a geometrization of dynamics.Comment: REVTeX, 24 pages with 20 PostScript figure

Fermion confinement induced by geometry

We consider a five-dimensional model in which fermions are confined in a hypersurface due to an interaction with a purely geometric field. Inspired by the Rubakov-Shaposhnikov field-theoretical model, in which massless fermions can be localized in a domain wall through the interaction of a scalar field, we show that particle confinement may also take place if we endow the five-dimensional bulk with a Weyl integrable geometric structure, or if we assume the existence of a torsion field acting in the bulk. In this picture, the kind of interaction considered in the Rubakov-Shaposhnikov model is replaced by the interaction of fermions with a geometric field, namely a Weyl scalar field or a torsion field. We show that in both cases the confinement is independent of the energy and the mass of the fermionic particle. We generalize these results to the case in which the bulk is an arbitrary n-dimensional curved space.Comment: 8 page

Geometric dynamical observables in rare gas crystals

We present a detailed description of how a differential geometric approach to Hamiltonian dynamics can be used for determining the existence of a crossover between different dynamical regimes in a realistic system, a model of a rare gas solid. Such a geometric approach allows to locate the energy threshold between weakly and strongly chaotic regimes, and to estimate the largest Lyapunov exponent. We show how standard mehods of classical statistical mechanics, i.e. Monte Carlo simulations, can be used for our computational purposes. Finally we consider a Lennard Jones crystal modeling solid Xenon. The value of the energy threshold turns out to be in excellent agreement with the numerical estimate based on the crossover between slow and fast relaxation to equilibrium obtained in a previous work by molecular dynamics simulations.Comment: RevTeX, 19 pages, 6 PostScript figures, submitted to Phys. Rev.

Conteúdo de minerais em ossos e no fígado de ovinos com ou sem periodontite

Universidade Federal do Pará. Faculdade de Medicina Veterinária. Castanhal, PA, Brasil.Universidade Federal do Pará. Faculdade de Medicina Veterinária. Castanhal, PA, Brasil.Universidade Federal do Pará. Faculdade de Medicina Veterinária. Castanhal, PA, Brasil.Universidade Federal Rural do Rio de Janeiro. Instituto de Zootecnia. Seropédica, RJ, Brasil.Universidade Federal Rural do Rio de Janeiro. Instituto de Zootecnia. Seropédica, RJ, Brasil.Universidade Federal Rural do Rio de Janeiro. Instituto de Zootecnia. Seropédica, RJ, Brasil.Universidade Federal Rural do Rio de Janeiro. Instituto de Veterinária. Seropédica, RJ, Brasil.Universidade Federal Rural do Rio de Janeiro. Instituto de Veterinária. Seropédica, RJ, Brasil.Universidade Federal Rural do Rio de Janeiro. Instituto de Veterinária. Seropédica, RJ, Brasil.Instituto Federal do Pará. Marabá, PA, Brasil.Instituto Federal do Pará. Marabá, PA, Brasil.Instituto Federal do Pará. Marabá, PA, Brasil.Universidade Federal do Sul e Sudoeste do Pará. Xinguara, PA, Brasil.Universidade Federal do Sul e Sudoeste do Pará. Xinguara, PA, Brasil.Universidade Federal do Sul e Sudoeste do Pará. Xinguara, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde e Ambiente. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde e Ambiente. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde e Ambiente. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Universidade Federal do Pará. Faculdade de Medicina Veterinária. Castanhal, PA, Brasil.Universidade Federal do Pará. Faculdade de Medicina Veterinária. Castanhal, PA, Brasil.Universidade Federal do Pará. Faculdade de Medicina Veterinária. Castanhal, PA, Brasil.Universidade Federal do Pará. Faculdade de Medicina Veterinária. Castanhal, PA, Brasil.Universidade Federal do Pará. Faculdade de Medicina Veterinária. Castanhal, PA, Brasil.Universidade Federal do Pará. Faculdade de Medicina Veterinária. Castanhal, PA, Brasil.Universidade Federal do Pará. Faculdade de Medicina Veterinária. Castanhal, PA, Brasil.Universidade Federal do Pará. Faculdade de Medicina Veterinária. Castanhal, PA, Brasil.Universidade Federal do Pará. Faculdade de Medicina Veterinária. Castanhal, PA, Brasil.Due to the supposed involvement of minerals in cases of ruminant periodontitis, this study aimed to analyze the concentrations of phosphorus (P) in bone, and cobalt (Co), copper (Co), iron (Fe), zinc (Zn) and selenium (Se) in liver of a cohort of sheep affected or not by periodontitis. From an outbreak of the disease in 2011 in Pará state, Brazil, rib and liver samples were obtained from 22 sheep with periodontitis and seven samples from healthy animals. Based on the concentrations of the different minerals in the tissues, we concluded that there was no relationship between periodontal disease in sheep with any mineral deficiency status. In contrast, most of the minerals in the tissues were above or within the recommended concentrations in bone and liver. Within the various aspects which until now have been studied regarding periodontitis in ruminants, the results obtained here corroborate the fact that periodontal disease in sheep is an infectious disease and it is not a consequence of the deficiency or excess of mineral elements in the diet

Theory on quench-induced pattern formation: Application to the isotropic to smectic-A phase transitions

During catastrophic processes of environmental variations of a thermodynamic system, such as rapid temperature decreasing, many novel and complex patterns often form. To understand such phenomena, a general mechanism is proposed based on the competition between heat transfer and conversion of heat to other energy forms. We apply it to the smectic-A filament growth process during quench-induced isotropic to smectic-A phase transition. Analytical forms for the buckling patterns are derived and we find good agreement with experimental observation [Phys. Rev. {\bf E55} (1997) 1655]. The present work strongly indicates that rapid cooling will lead to structural transitions in the smectic-A filament at the molecular level to optimize heat conversion. The force associated with this pattern formation process is estimated to be in the order of $10^{-1}$ piconewton.Comment: 9 pages in RevTex form, with 3 postscript figures. Accepted by PR