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Maceio, Brazil

Located in the city of Maceió, the Federal University of Alagoas is the major university in coastal state Alagoas and one of the main research centers in Brazilian north eastern region . It is located very near the city's airport. Wikipedia.

Silva J.P.,Federal University of Alagoas
Journal of medicinal food | Year: 2010

Bowdichia virgilioides Kunth (Family Fabaceae) is a plant that is distributed widely in the tropical and subtropical regions of the world. In the northeast region of Brazil, where B. virgilioides is called "sucupira-preta," the stem bark is used in folk medicine to treatment of inflammatory and painful diseases. This study aimed to evaluate the antinociceptive activity of the aqueous extract of the dried stem bark of B. virgilioides. The aqueous extract of B. virgilioides in doses of 50, 100, 200, and 400 mg/kg was administered orally 1 hour prior to pain induction. Only the doses of 200 and 400 mg/kg produced an inhibition by 61% and 74%, respectively, in the number of abdominal writhings induced by acetic acid. This antinociceptive effect was not reversed by pretreatment with naloxone, indicating that the effect is not associated with the activation of opioid receptors. In the formalin test, using the two highest doses, the extract had no effect in the first phase but produced an analgesic effect on the second phase with the inhibition of licking time (P < .001). In the hot plate test, no effect was seen at the dose of 400 mg/kg p.o. Our findings show that B. virgilioides contains pharmacologically active constituents that possess antinociceptive activity justifying its popular therapeutic use in treating conditions associated with the painful conditions. Source

Silva G.T.,Federal University of Alagoas
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control | Year: 2011

In this paper, the scattering of an ultrasound zero-order Bessel beam by a rigid sphere in the off-axis configuration is studied. The beam is described through the partial wave expansion. The beam-shape coefficients which represent the amplitude of each multipole mode of the partial wave expansion are computed by numerical quadrature. Calculations are presented for both near- and far-field off-axis scattering. The far-field scattering is examined in both Rayleigh and geometrical acoustic limits. Results demonstrate that the scattered pressure in the off-axis case may significantly deviate from that in the on-axis configuration. In addition, the directive pattern of the scattered pressure is highly dependent on the relative position of the beam to the sphere. © 2006 IEEE. Source

Silva G.T.,Federal University of Alagoas
Journal of the Acoustical Society of America | Year: 2011

Most studies investigating the acoustic radiation force upon a target are based on symmetry considerations between the object and the incident beam. Even so, this symmetry condition is not always fulfilled in several cases. An expression for the radiation force is obtained as a function of the beam-shape and the scattering coefficients of an incident wave and the object, respectively. The expression for the radiation force caused by a plane wave on a rigid sphere is used to validate the formula. This method represents a theoretical advance permitting different interpretations and predictions concerned to the acoustic radiation force phenomenon. © 2011 Acoustical Society of America. Source

Silva G.T.,Federal University of Alagoas
Journal of the Acoustical Society of America | Year: 2014

Exact formulas of the acoustic radiation force and torque exerted by an arbitrary time-harmonic wave on an absorbing compressible particle that is suspended in an inviscid fluid are presented. It is considered that the particle diameter is much smaller than the incident wavelength, i.e., the so-called Rayleigh scattering limit. Moreover, the particle absorption assumed here is due to the attenuation of compressional waves only. Shear waves inside and outside the particle are neglected, since the inner and outer viscous boundary layer of the particle are supposed to be much smaller than the particle radius. The obtained radiation force formulas are used to establish the trapping conditions of a particle by a single-beam acoustical tweezer based on a spherically focused ultrasound transducer. In this case, it is shown that the particle absorption has a pivotal role in single-beam trapping at the transducer focal region. Furthermore, it is found that only the first-order Bessel vortex beam can generate the radiation torque on a small particle. In addition, numerical evaluation of the radiation force and torque exerted on a benzene and an olive oil droplet suspended in water are presented and discussed. © 2014 Acoustical Society of America. Source

De Moura F.A.B.F.,Federal University of Alagoas
Physica D: Nonlinear Phenomena | Year: 2013

In this paper, we study numerically the one-electron dynamics in a Fermi-Pasta-Ulam disordered chain. In our model the atoms are coupled by a random harmonic force and a nonlinear cubic potential. The electron-lattice interaction was considered such that the kinetic energy of the electrons depends on the effective distance between neighboring atoms. Basically, the hopping term will increase exponentially when the distance between neighboring atoms decreases. By solving numerically the equations describing the dynamics for the electron and lattice, we can compute the spreading of an initially localized electronic wavepacket. Our results suggest that the soliton excitation induced by the nonlinear cubic interaction present in the Hamiltonian can control the electron dynamics across the entire lattice. We report numerical evidence of the existence of a soliton-electron pair in Fermi-Pasta-Ulam disordered chains. We discuss in detail the conditions necessary for promoting the electron transport mediated by solitons in this model. © 2013 Elsevier B.V. All rights reserved. Source

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