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Search Results: 1 - 10 of 242439 matches for " Sergio R. Lopes "
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Nonintegrable Interaction of Ion-Acoustic and Electromagnetic Waves in a Plasma
Felipe B. Rizzato,Sergio R. Lopes,Abraham C. -L. Chian
Physics , 1996, DOI: 10.1103/PhysRevE.55.3423
Abstract: In this paper we re-examine the one-dimensional interaction of electromagnetic and ion acoustic waves in a plasma. Our model is similar to one solved by Rao et al. (Phys. Fluids, vol. 26, 2488 (1983)) under a number of analytical approximations. Here we perform a numerical investigation to examine the stability of the model. We find that for slightly over dense plasmas, the propagation of stable solitary modes can occur in an adiabatic regime where the ion acoustic electric field potential is enslaved to the electromagnetic field of a laser. But if the laser intensity or plasma density increases or the laser frequency decreases, the adiabatic regime loses stability via a transition to chaos. New asymptotic states are attained when the adiabatic regime no longer exists. In these new states, the plasma becomes rarefied, and the laser field tends to behave like a vacuum field.
Avalia??o experimental de redes mesh com os classmate pcs da Intel
Garay, Jorge R. Beingolea;Hiramatsu, Roberto K.;Kofuji, Sergio T.;Lopes, Roseli de Deus;
JISTEM - Journal of Information Systems and Technology Management , 2008, DOI: 10.4301/S1807-17752008000200003
Abstract: this paper shows performance evaluation results of a wireless mesh network employing an 802.11s standard and low cost intel classmate pcs. the experiments consist of throughput and coverage range determination, in indoor and outdoor scenarios, in which net and communication multihop coverage tests were done. the results show maximum throughput of 14 mbps for tcp and 12 mbps for udp respectively, proving the proposed solution's viability for the digital inclusion process in public schools.
Sump syndrome: relato de caso
Lopes Junior, Ascêncio Garcia;Fuganti, Paulo Emílio;Spinosa, Sergio R.;
Revista do Colégio Brasileiro de Cirurgi?es , 2007, DOI: 10.1590/S0100-69912007000500016
Abstract: sump syndrome after choledochoduodenostomy is becoming rare, mainly because endoscopic procedures are replacing this surgery. we report a case of this syndrome where the only symptom was pain. the diagnosis was made after 3 years and many doctors attended the patient. the treatment was endoscopic and the result was excellent.
Efeito do genótipo halotano e de diferentes sistemas de produ o na qualidade da carne suína
Bridi Ana Maria,Rübensam Jane Maria,Nicolaiewsky Sergio,Lopes Rui Fernando Felix
Revista Brasileira de Zootecnia , 2003,
Abstract: Verificou-se o efeito dos genótipos halotano homozigoto dominante e heterozigoto e dos sistemas de cria o confinado sobre piso de cimento, confinado sobre cama de maravalha e ao ar livre sobre a qualidade da carne suína. Foram utilizados 96 suínos machos castrados selecionados através do exame de DNA gen mico, utilizando-se a técnica de rea o em cadeia de polimerase (PCR) para amplificar a regi o do receptor rianodina. A regi o amplificada foi clivada pela técnica polimorfismo do comprimento dos fragmentos de restri o (RFLP). Mediu-se o pH nos músculos Longissimus dorsi e Semimembranosus aos quarenta e cinco minutos e vinte e quatro horas após o abate. A capacidade de reten o de água foi avaliada em amostras do músculo Longissimus dorsi através das técnicas de perda de líquido por gotejamento, de coc o e de descongelamento. Escores para a cor e o grau de marmoriza o da carne foram atribuídos com auxílio de padr es fotográficos. A maciez da carne foi medida pela for a de cisalhamento em equipamento Warner-Bratzler Shear. Suínos com gene halotano heterozigotos apresentaram valores inferiores de pH, menor capacidade de reten o de água e uma freqüência de carca as com carne PSE três vezes maior. O sistema de cria o n o afetou os valores de pH inicial e final ou a capacidade de reten o de água da carne suína. A maior incidência de carne PSE foi observada nas carca as dos suínos criados em sistema confinado sobre piso de concreto. N o houve efeito significativo da intera o genótipo halotano e sistema de cria o para as características avaliadas.
Jorge R. Beingolea Garay,Roberto K. Hiramatsu,Sergio T. Kofuji,Roseli de Deus Lopes
JISTEM - Journal of Information Systems and Technology Management , 2008,
Abstract: This paper shows performance evaluation results of a wireless mesh network employing an 802.11s standard and low cost Intel Classmate PCs. The experiments consist of throughput and coverage range determination, in indoor and outdoor scenarios, in which net and communication multihop coverage tests were done. The results show maximum throughput of 14 Mbps for TCP and 12 Mbps for UDP respectively, proving the proposed solution’s viability for the digital inclusion process in public schools.
Periodic orbit analysis at the onset of the unstable dimension variability and at the blowout bifurcation
Rodrigo Frehse Pereira,Sandro Ely de Souza Pinto,Ricardo L. Viana,Sergio R. Lopes,Celso Grebogi
Physics , 2009, DOI: 10.1063/1.2748619
Abstract: Many chaotic dynamical systems of physical interest present a strong form of nonhyperbolicity called unstable dimension variability (UDV), for which the chaotic invariant set contains periodic orbits possessing different numbers of unstable eigendirections. The onset of UDV is usually related to the loss of transversal stability of an unstable fixed point embedded in the chaotic set. In this paper, we present a new mechanism for the onset of UDV, whereby the period of the unstable orbits losing transversal stability tends to infinity as we approach the onset of UDV. This mechanism is unveiled by means of a periodic orbit analysis of the invariant chaotic attractor for two model dynamical systems with phase spaces of low dimensionality, and seems to depend heavily on the chaotic dynamics in the invariant set. We also described, for these systems, the blowout bifurcation (for which the chaotic set as a whole loses transversal stability) and its relation with the situation where the effects of UDV are the most intense. For the latter point, we found that chaotic trajectories off, but very close to, the invariant set exhibit the same scaling characteristic of the so-called on-off intermittency.
Periodic-orbit analysis and scaling laws of intermingled basins of attraction in an ecological dynamical system
Rodrigo Frehse Pereira,Sabrina Camargo,Sandro Ely de Souza Pinto,Sergio R. Lopes,Ricardo L. Viana
Physics , 2009, DOI: 10.1103/PhysRevE.78.056214
Abstract: Chaotic dynamical systems with two or more attractors lying on invariant subspaces may, provided certain mathematical conditions are fulfilled, exhibit intermingled basins of attraction: Each basin is riddled with holes belonging to basins of the other attractors. In order to investigate the occurrence of such phenomenon in dynamical systems of ecological interest (two-species competition with extinction) we have characterized quantitatively the intermingled basins using periodic-orbit theory and scaling laws. The latter results agree with a theoretical prediction from a stochastic model, and also with an exact result for the scaling exponent we derived for the specific class of models investigated. We discuss the consequences of the scaling laws in terms of the predictability of a final state (extinction of either species) in an ecological experiment.
Riddling and chaotic synchronization of coupled piecewise-linear Lorenz maps
Marcos C. Verges,Rodrigo Frehse Pereira,Sergio R. Lopes,Ricardo L. Viana,Tomasz Kapitaniak
Physics , 2009, DOI: 10.1016/j.physa.2009.02.015
Abstract: We investigate the parametric evolution of riddled basins related to synchronization of chaos in two coupled piecewise-linear Lorenz maps. Riddling means that the basin of the synchronized attractor is shown to be riddled with holes belonging to another basin in an arbitrarily fine scale, which has serious consequences on the predictability of the final state for such a coupled system. We found that there are wide parameter intervals for which two piecewise-linear Lorenz maps exhibit riddled basins (globally or locally), which indicates that there are riddled basins in coupled Lorenz equations, as previously suggested by numerical experiments. The use of piecewise-linear maps makes it possible to prove rigorously the mathematical requirements for the existence of riddled basins.
Anomalous transport induced by nonhyperbolicity
Sergio R. Lopes,José D. Szezech Jr.,Rodrigo F. Pereira,Ricardo L. Viana,Andressa B. Bertolazzo
Physics , 2012, DOI: 10.1103/PhysRevE.86.016216
Abstract: In this letter we study how deterministic features presented by a system can be used to perform direct transport in a {\it quasi}-symmetric potential and weak dissipative system. We show that the presence of nonhyperbolic regions around acceleration areas of the phase space plays an important role in the acceleration of particles giving rise to direct transport in the system. Such effect can be observed for a large interval of the weak asymmetric potential parameter allowing the possibility to obtain useful work from unbiased nonequilibrium fluctuation in real systems even in a presence of a {\it quasi}-symmetric potential.
Efeito do genótipo halotano e de diferentes sistemas de produ??o na qualidade da carne suína
Bridi, Ana Maria;Rübensam, Jane Maria;Nicolaiewsky, Sergio;Lopes, Rui Fernando Felix;Lobato, José Fernando Piva;
Revista Brasileira de Zootecnia , 2003, DOI: 10.1590/S1516-35982003000600011
Abstract: the effect of halothane genotypes (heterozygous and dominant homozygous) and intensive rearing systems (indoor, wood shavings bedding and outdoor) on pork quality were determinated. ninety six castrated male pigs were used for the trial. identification of the halothane genotype was determined in blood samples using the dna-test, based on the polymerase chain reaction (pcr) amplification of the critical region of the ryanodine receptor and subsequent restricion of the amplifield fragment by the restriction fragment lengh polymorfism (rflp) technique. the ph at 45 minutes and 24 hours after slaughter was measured on the longissimus dorsi and semimembranosus muscles. at the laboratory, the longissimus dorsi muscle was used for the evaluation of the color, marbling, drip loss, defrosting loss and cooking loss and shear force. the muscle of heterozygous pigs for the halothane gene had lower ph and higher drip loss and the incidence of the pse condition in this genotype was three times higher. the rearing system did not affect the initial and ultimate ph or water holding capacity. indoor reared pigs had greater frequency of pse carcass. the interaction between halothane genotypes and rearing systems had no significant effect on any trait studied.
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