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Search Results: 1 - 10 of 201960 matches for " P. Cavalcante "
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ENSAIO SOBRE OS PROCESSOS FON TICO intra-segmentar NA L NGUA KAINGANG ESSAY ON THE INTRASEGMENTAL PHONETIC PROCESSES IN THE KAINGANG LANGUAGE
Marita P?′rto Cavalcante
Signótica , 1993, DOI: 10.5216/sig.v5i1.7360
Abstract: Este artigo nos mostra a necessidade de desenvolvermos um tratamento fonol 3gico n £o-padr £o para dar conta dos segmentos complexos da l -ngua Kaingang - as regras fonol 3gicas intrassegmentais. This article shows us the necessity to develop a non-standard phonological treatment to deal adequately with the complex segments of the Kaingang language - intrasegmental phonological rules.
Convexity in locally conformally flat manifolds with boundary
Marcos P. Cavalcante
Mathematics , 2007,
Abstract: Given a closed subset $\La$ of the open unit ball $B_1\subset \real^n$, $n \geq 3$, we will consider a complete Riemannian metric $g$ on $\bar{B_1} \setminus \La$ of constant scalar curvature equal to $n(n-1)$ and conformally related to the Euclidean metric. In this paper we prove that every closed Euclidean ball $\bar{B} \subset B_1\setminus \La$ is convex with respect to the metric $g$, assuming the mean curvature of the boundary $\partial B_1$ is nonnegative with respect to the inward normal.
Phase-shift definition for pion-nucleon scattering from chiral perturbation theory
Cavalcante, Isabela P.;Borges, J. Sá;
Brazilian Journal of Physics , 2004, DOI: 10.1590/S0103-97332004000200024
Abstract: chiral perturbation theory is considered as a very precise method when applied to pion-nucleon scattering near threshold and in the unphysical region since in these cases the pion momenta are small. in this framework, third order calculation yields a non-relativistic scattering amplitude with nine free parameters. from the fact that the resulting partial-wave amplitudes do not respect elastic unitarity relation, one has that the phase-shift definition is ambiguous. in this article, we present the comparison of the model with experimental data for two different phase-shift formulas and we conclude that the results are very sensitive to phase-shift definition.
Uso de resíduo industrial a base de resina fenólica como carga para o polipropileno
Cavalcante, André P.;Canto, Leonardo B.;
Polímeros , 2012, DOI: 10.1590/S0104-14282012005000031
Abstract: the aim of this study was to assess the technical feasibility of using industrial waste composed of phenolic resin, lignocellulose, calcium carbonate, talc, mica and carbon black as filler for polypropylene (pp). composites of pp with 10, 15 and 20 wt% of the waste were processed in a twin-screw extruder followed by injection molding. molded composites were characterized by scanning electron microscopy (sem), thermal analyses (dsc and tga), mechanical tests (tensile, flexural and impact) and thermo-mechanical test (hdt). the composites showed residue particles with sizes less than 500 μm dispersed in the pp matrix. the residue particles acted as nucleating agents for pp crystallization. the composites showed greater thermal degradation resistance as compared to pp. the composites showed a balance of stiffness and mechanical strength with increase of the flexural module and decrease of the tensile strength. the notched impact strength was not altered and the heat distortion temperature (hdt) of the composites was increased as compared to pp. the performance of the composites developed here showed that the industrial waste based on phenolic resin can be used as functional filler for pp. furthermore, these composites are an alternative for the recycling of the phenolic resin industrial waste.
On the asymptotic Bieberbach conjecture
Mauriso Alves,Armando J. P. Cavalcante
International Journal of Mathematics and Mathematical Sciences , 1982, DOI: 10.1155/s0161171282000507
Abstract: The set S consists of complex functions f, univalent in the open unit disk, with f(0)=f ¢ € 2(0) ¢ ’1=0. We use the asymptotic behavior of the positive semidefinite FitzGerald matrix to show that there is an absolute constant N0 such that, for any f(z)=z+ ¢ ‘n=2 ¢ anzn ¢ S with |a3| ¢ ‰ ¤2.58, we have |an|N0.
Phase-shift definition for pion-nucleon scattering from chiral perturbation theory
Cavalcante Isabela P.,Borges J. Sá
Brazilian Journal of Physics , 2004,
Abstract: Chiral Perturbation Theory is considered as a very precise method when applied to pion-nucleon scattering near threshold and in the unphysical region since in these cases the pion momenta are small. In this framework, third order calculation yields a non-relativistic scattering amplitude with nine free parameters. From the fact that the resulting partial-wave amplitudes do not respect elastic unitarity relation, one has that the phase-shift definition is ambiguous. In this article, we present the comparison of the model with experimental data for two different phase-shift formulas and we conclude that the results are very sensitive to phase-shift definition.
Nucleon-nucleon interaction in the Skyrme model
Isabela P. Cavalcante,Manoel R. Robilotta
Physics , 2000, DOI: 10.1103/PhysRevC.63.044008
Abstract: We consider the interaction of two skyrmions in the framework of the sudden approximation. The widely used product ansatz is investigated. Its failure in reproducing an attractive central potential is associated with terms that violate G-parity. We discuss the construction of alternative ans\"atze and identify a plausible solution to the problem.
Crossing Symmetry Violation of Unitarized Pion-Pion Amplitude in the Resonance Region
Isabela P. Cavalcante,J. Sá Borges
Physics , 2001, DOI: 10.1088/0954-3899/28/6/315
Abstract: Pion-pion scattering amplitude obtained from one-loop Chiral Perturbation Theory (ChPT) is crossing symmetric, however the corresponding partial wave amplitudes do not respect exact unitarity relation. There are different approaches to get unitarized partial wave amplitudes from ChPT. Here we consider the inverse amplitude method (IAM) that is often used to fit pion-pion phase shifts to experimental data, by adjusting free parameters. We measure the amount of crossing symmetry violation (CSV) in this case and we show that crossing symmetry is badly violated by the IAM unitarized ChPT amplitude in the resonance region. Important CSV also occurs when all free parameters are set equal to zero.
Unitarized ChPT Amplitudes and Crossing Symmetry Violation
Isabela P. Cavalcante,J. Sá Borges
Physics , 2001,
Abstract: Pion-pion scattering amplitude obtained from one-loop Chiral Perturbation Theory (ChPT) is crossing symmetric, however the corresponding partial-wave amplitudes do not respect exact unitarity relation. There are different approaches to get unitarized results from ChPT. Here we consider the inverse amplitude method (IAM) and, using the Roskies relations, we measure the amount of crossing symmetry violation when IAM is used in order to fit pion-pion phase-shifts to experimental data in the resonance region. We also show the unitarity violation of the crossing symmetric ChPT amplitude with its parameters fixed in order to fit to experimental phase-shifts.
Pion-Pion Phase-Shifts and the Value of Quark-Antiquark Condensate in the Chiral Limit
Isabela P. Cavalcante,J. Sá Borges
Physics , 2001, DOI: 10.1103/PhysRevD.63.114022
Abstract: We use low energy pion-pion phase-shifts in order to make distinction between the alternatives for the value of the quark-antiquark condensate $B_0$ in the chiral limit. We will consider the amplitude up to and including ${\cal O}(p^4)$ contributions within the Standard and Generalized Chiral Perturbation Theory frameworks. They are unitarized by means of Pad\'e approximants in order to fit experimental phase-shifts in the resonance region. As the best fits correspond to $\alpha = \beta = 1$, we conclude that pion-pion phase-shift analysis favors the standard ChPT scenario, which assumes just one, large leading order parameter $<\bar q q >_{_0}$.
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