Federal University of Alagoas

www.ufal.edu.br/ufal
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.


Time filter

Source Type

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.


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.


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.


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.


Silva G.T.,Federal University of Alagoas | Baggio A.L.,Federal University of Alagoas
Ultrasonics | Year: 2015

The concept of a single-beam acoustical tweezer device which can simultaneously trap microparticles at different points is proposed and demonstrated through computational simulations. The device employs an ultrasound beam produced by a circular focused transducer operating at 1 MHz in water medium. The ultrasound beam exerts a radiation force that may tweeze suspended microparticles in the medium. Simulations show that the acoustical tweezer can simultaneously trap microparticles in the pre-focal zone along the beam axis, i.e. between the transducer surface and its geometric focus. As acoustical tweezers are fast becoming a key instrument in microparticle handling, the development of acoustic multitrapping concept may turn into a useful tool in engineering these devices. © 2014 Elsevier B.V. All rights reserved.


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.


The purpose this study was to examine the effects of caffeine ingestion on performance and energy expenditure (anaerobic and aerobic contribution) during a 4-km cycling time trial (TT) performed after a carbohydrate (CHO) availability-lowering exercise protocol. After preliminary and familiarization trials, seven amateur cyclists performed three 4-km cycling TT in a double-blind, randomized and crossover design. The trials were performed either after no previous exercise (CON), or after a CHO availability-lowering exercise protocol (DEP) performed in the previous evening, followed by either placebo (DEP-PLA) or 5 mg.kg(-1) of caffeine intake (DEP-CAF) 1 hour before the trial. Performance was reduced (-2.1%) in DEP-PLA vs CON (421.0±12.3 vs 412.4±9.7 s). However, performance was restored in DEP-CAF (404.6±17.1 s) compared with DEP-PLA, while no differences were found between DEP-CAF and CON. The anaerobic contribution was increased in DEP-CAF compared with both DEP-PLA and CON (67.4±14.91, 47. 3±14.6 and 55.3±14.0 W, respectively), and this was more pronounced in the first 3 km of the trial. Similarly, total anaerobic work was higher in DEP-CAF than in the other conditions. The integrated electromyographic activity, plasma lactate concentration, oxygen uptake, aerobic contribution and total aerobic work were not different between the conditions. The reduction in performance associated with low CHO availability is reversed with caffeine ingestion due to a higher anaerobic contribution, suggesting that caffeine could access an anaerobic "reserve" that is not used under normal conditions.


De Moura F.A.B.F.,Federal University of Alagoas
European Physical Journal B | Year: 2010

We study the one-electron eigenstates in a two-dimensional (2d) Anderson model with long-range correlated off-diagonal disorder, generated by a 2d discrete Fourier method. The dynamics of an initially localized wave packet is investigated by numerically solving the 2d time-dependent Schrödinger equation. In additional the participation number and its scaling behavior was obtained through direct diagonalization. Our numerical data suggest that the system exhibits a ballistic dynamics in the strongly correlated disorder regime. Moreover, the scaling analysis of mean participation number around the band center also indicates the presence of extended states for high degree of correlations. © 2010 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.


Mariz T.,Federal University of Alagoas
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

The first higher derivative term of the photon sector of Lorentz-violating QED, with an operator of mass dimension d=5, is radiatively induced from the fermion sector, which contains a derivative term with the dimensionless coefficient gλμν. The calculation is performed perturbatively in the coefficient for Lorentz violation, and, due to the fact that the contributions are quadratically divergent, we adopt dimensional regularization. © 2011 American Physical Society.


Patent
Federal University of Alagoas | Date: 2011-06-28

The application of extracts, mainly the alcoholic, hydroalcoholic, and aqueous extracts of the bark, bark seam, stem, and seedpod skin of Abarema cochliocarpos (Gomes) Barneby & Grimes and/or Stryphnodendron barbatiman, Stryphnodendron coriaceum Benth., S. diacolor Benth., S. pulcherrimum (Wildd) Hoch., Stryphnodendron adstringens (Mart.) Coville, Stryphnodendron obovatum Benth., Stryphnodendron polyphyllum M., and Pithecellobium avaremotemo Mart., all popularly known as barbatimo, as adjuvants in pharmaceutical compositions for treatment of infections related to the human papillomavirus (HPV) and cervical cancer prophylaxis.

Loading Federal University of Alagoas collaborators
Loading Federal University of Alagoas collaborators