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Betemps M.A.,Instituto Federal Of Educacao | MacHado M.V.T.,High Energy Physics Phenomenology Group
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

We apply the target rest frame formalism to photon+heavy quark production cross section in hadronic collisions at high energies. We investigate the dependence of the production cross section on the photon and quark rapidities and transverse momenta. It is shown that the photon transverse momentum spectrum is a sensitive probe of color dipole scattering amplitude. The theoretical results are compared to Tevatron measurements of the differential γ+c+X and γ+b+X production cross sections at √s=1.96TeV. An analysis for proton-proton and proton-lead collisions at the LHC regime is also performed. © 2010 The American Physical Society.

Cruz W.T.,Instituto Federal Of Educacao | Lima A.R.P.,University da Integracao Internacional da Lusofonia Afro Brasileira | Almeida C.A.S.,Federal University of Ceará
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We present new results on the localization of gauge fields in thick brane models. The four-dimensional observable universe is considered to be a topological defect which is generated by two scalar fields coupled with gravity embedded in a five-dimensional space-time. Like other thick brane models, the Bloch brane setup is not capable of supporting gauge field localization. In order to circumvent this problem we include the dilaton field and, as a result, obtain normalizable solutions. In addition, by writing the equations of motion as Schrödinger-like equations, we have found new kinds of resonances in the massive spectrum which appear also for heavy modes. This is in sharp contrast to what is commonly found in previous analog studies, where only light modes become resonant. At specific energies, the wave solutions exhibit very high amplitudes within the membrane. The influence of the dilaton coupling and of the internal structure on the resonant modes are also discussed. © 2013 American Physical Society.

Alencar I.D.C.C.,Instituto Federal Of Educacao | Azevedo C.O.,Federal University of Espirito Santo
Systematic Entomology | Year: 2013

Epyrini (Epyrinae) are the largest and morphologically most diverse group within Bethylidae. Evans' conception of Epyrini induces misclassification of several taxa and their diagnostic features, such as median lobe of clypeus projected, and fovea in lateroposterior angle of propodeal disc, are insufficient to place species in the tribe. No previous comprehensive cladistic study has recovered Epyrini as a clade, and no synapomorphies are reported for the tribe, suggesting that the group is artificial. We infer a phylogeny based on 391 informative morphological characters for 42 terminal taxa (31 ingroup, 11 outgroup). Monophyly of Epyrini is supported by a petiole with fused root and body as an autapomorphy. Anisepyris Kieffer, Laelius Ashmead, Holepyris Kieffer, Formosiepyris Terayama, Disepyris Kieffer, Bakeriella Kieffer and Trachepyris Kieffer were retrieved as monophyletic. Epyris Westwood and Chlorepyris Kieffer are paraphyletic. The addition of new characters was essential to define Epyrini, and the ventral region of the mesosoma, petiole and male genitalia may help to better understand genera and species limits. All resulting trees indicate that Epyrinae are polyphyletic. Tribes Epyrini and Sclerodermini are revalidated to subfamily status. © 2012 The Royal Entomological Society.

Carvalho-Santos V.L.,Instituto Federal Of Educacao | Dandoloff R.,Cergy-Pontoise University
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2012

We study the nonlinear σ-model in an external magnetic field applied on curved surfaces with rotational symmetry. The Euler-Lagrange equations derived from the Hamiltonian yield the double sine-Gordon equation (DSG) provided the magnetic field is tuned with the curvature of the surface. A 2π skyrmion appears like a solution for this model and surface deformations are predicted at the sector where the spins point in the opposite direction to the magnetic field. We also study some specific examples by applying the model on three rotationally symmetric surfaces: the cylinder, the catenoid and the hyperboloid. © 2012 Elsevier B.V.

Cruz W.T.,Instituto Federal Of Educacao | Gomes A.R.,Federal University of Maranhão | Almeida C.A.S.,Federal University of Ceará
European Physical Journal C | Year: 2011

In this work we investigate the issue of fermion localization and resonances in (4,1)-deformed branes constructed with one scalar field coupled with gravity. Such models provide us branes with internal structures that turns the gravitational interaction more effective for fermions aside the brane, increasing their lifetime. The coupling between the scalar field and spinors is a necessary condition for fermions to be localized on such branes. After performing a chiral decomposition of the five-dimensional spinor we found resonances with both chiralities. The correspondence between the spectra for left and right chirality is guaranteed and Dirac fermions are realized on the brane. © Springer-Verlag / Società Italiana di Fisica 2011.

Farias M.,Instituto Federal Of Educacao | Martinelli M.,Federal University of Rio Grande do Sul | Rolim G.K.,Federal University of Rio Grande do Sul
Applied Catalysis A: General | Year: 2011

Heterogeneous catalyst was obtained by the direct immobilization of molybdenum compound on montmorillonite K10 clay. The resultant solid was characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray diffractometry (XRD), scanning electron microscopy coupled in a energy dispersive X-ray spectrometer (SEM-EDS), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller and Barret-Joyner-Halenda isotherms (BET/BJH), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis-DRS) and Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR). The catalyst was tested for the epoxidation of both soybean and castor oils, using tert-butyl hydroperoxide (TBHP) as oxidizing agent. After the first use, the immobilized catalyst showed an enhanced activity and also catalytic stability in recycling experiments. The best results for epoxidation reactions concerning castor oil were observed under conditions of 80 °C for 24 h (100% conversion and 75% selectivity) and catalytic reuse. © 2011 Elsevier B.V. All rights reserved.

Maluf R.V.,Federal University of Ceará | Silva J.E.G.,Federal University of Ceará | Cruz W.T.,Instituto Federal Of Educacao | Almeida C.A.S.,Federal University of Ceará
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

In this work, we study the modified Dirac equation in the framework of very special relativity (VSR). The low-energy regime is accessed and the nonrelativistic Hamiltonian is obtained. It turns out that this Hamiltonian is similar to that achieved from the Standard Model Extension (SME) via coupling of the spinor field to a Lorentz-violating term, but new features arise inherited from the non-local character of the VSR. In addition, the implications of the VSR-modified Lorentz symmetry on the spectrum of a hydrogen atom are determined by calculating the first-order energy corrections in the context of standard quantum mechanics. Among the results, we highlight that the modified Hamiltonian provides non-vanishing corrections which lift the degeneracy of the energy levels and allow us to find an upper bound upon the VSR-parameter. © 2014 The Authors.

Cruz W.T.,Instituto Federal Of Educacao | Sousa L.J.S.,Instituto Federal Of Educacao | Maluf R.V.,Federal University of Ceará | Almeida C.A.S.,Federal University of Ceará
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

This work presents new results about the graviton massive spectrum in two-field thick branes. Analyzing the massive spectra with a relative probability method we have firstly showed the presence of resonance structures and obtained a connection between the thickness of the defect and the lifetimes of such resonances. We obtain another interesting result considering the degenerate Bloch brane solutions. In these thick brane models, we have the emergence of a splitting effect controlled by a degeneracy parameter. When the degeneracy constant tends to a critical value, we have found massive resonances to the gravitational field indicating the existence of modes highly coupled to the brane. We also discussed the influence of the brane splitting effect over the resonance lifetimes. © 2014.

Availability of P for sugarcane plants was evaluated in a soil treated with organic composts rich in silicon. Five composts were formulated with following wastes: sugarcane bagasse, ashes of sugarcane bagasse, filter cake and castor bean plant residue enriched with silicon powdered rocks. The treatments consisted of five doses (0, 13, 26, 52 e 104 t ha-1) of each compost and an additional treatment with mineral fertilization (NPK). Soil samples were collected after the application of the treatments in order to carry out the following analyses: equilibrium P, "available" Si, total organic C, and fractionation of the organic substances. The plant was sampled 150 days after planting for analysis of the leaf P. The application of composts made possible reduction of the adsorption of soil P, contributing to raise the absorption of this element by sugarcane crop; the reduction of the adsorption of P in the soil was atributed to Si from rocks of silicon, and the humic substances from composts and the compost containing ashes of sugarcane bagasse did not contribute to elevate content of "available" Si in the soil.

De Araujo Ribeiro R.L.,Federal University of Rio Grande do Norte | De Azevedo C.C.,Instituto Federal Of Educacao | De Sousa R.M.,Federal University of Rio Grande do Norte
IEEE Transactions on Power Electronics | Year: 2012

This paper introduces a robust adaptive control strategy of shunt active power filters ( SAPF) for power-factor correction, harmonic compensation, and balancing of nonlinear loads. The proposed control scheme is implemented without load harmonic detection. The compensation constraints are obtained by regulating indirectly the currents of the power mains. The reference currents of SAPF are generated by the dc-link voltage controller based on the active power balance of system. They are aligned to the phase angle of the power mains voltage vector, by using a dq phase-locked loop system. The current control strategy is implemented by an adaptive pole-placement control strategy integrated to a variable structure control scheme. This control scheme uses the internal model principle of reference currents for achieving the zero steady-state tracking error. Experimental results are shown for determining the effectiveness of an SAPF-proposed control system. © 2011 IEEE.

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