201 resultados para soliton retardation


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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The evolution of surface water waves in finite depth under wind forcing is reduced to an antidissipative Korteweg-de Vries-Burgers equation. We exhibit its solitary wave solution. Antidissipation accelerates and increases the amplitude of the solitary wave and leads to blow-up and breaking. Blow-up occurs in finite time for infinitely large asymptotic space so it is a nonlinear, dispersive, and antidissipative equivalent of the linear instability which occurs for infinite time. Due to antidissipation two given arbitrary and adjacent planes of constant phases of the solitary wave acquire different velocities and accelerations inducing breaking. Soliton breaking occurs in finite space in a time prior to the blow-up. We show that the theoretical growth in amplitude and the time of breaking are both testable in an existing experimental facility.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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In this study were carried out toxicity tests and the evaluation of sub lethal effects of the insecticides malathion and fipronil, over the test system of Girardia tigrina, using for these analyses a great variety of methods. For evaluation of the lethal concentrations of the products, adult planarians were exposed to several different concentrations. All the tests were carried out in duplicate, maintained on the shelter of the light, on a temperature 24-26ºC and they had the duration of 96h, with observations at each 24h. The results were statically valued by the tests U of Mann- Whitney, Spearman-Karber, ANOVA and Pearson correlation. The effects over the system-test, in the different tested concentrations, varied in accordance with the time of exposition. The EC50 given by the test of Spearman-Karber was of 12,5mg/L for malathion and 13,4mg/L for fipronil. The evaluation of sub lethal effects was composed by analyses of the potential of regeneration; histological, for tissue damage evaluation; d; and the “comet assay”, for DNA damage detection. The specimens split up and exposed to the insecticides demonstrated, between other effects, retardation in development of the regenerative blastema. The histological evaluation has shown that exposed planarians to lower concentrations of the insecticides cause more significant damage against the tissues and some specific cell types. Through the comet assay, significant damages were noticed in the DNA in all the treatments, when compared with the control group. Such damages may result in reproduction and immunity alterations, which reduce the competitive efficiency and, consequently, the survival chances of these organisms.

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The paper talks about the education of persons with disabilities severe mental retardation based on the idea of Reuven Feuerstein mediation. The collected data were analysed mainly under the focus quantitative, allowing extraction of details of everyday life investigated. Aims to describe and analyze the implementation process their educational, focusing on teaching strategies used by Special Education teachers in the Araraquara’s city. In addition, seeks to address the educational process of a population slightly investigated by uniting two strands of thread in an innovative way: the Theory of Structural Cognitive Modifiability (SCM) and Reuven Feuerstein education of students with severe cognitive impairment. The methodology initiated by the establishment of the teacher’s profile, their mapping and location. Data collection was achieved through three instruments: interviews with teachers, observation protocol and field diary for registration. Our results describe the work of a teacher, showing their practice, and enlist the pedagogical strategies used, mainly those related to the criteria medication. According to the Theory of Structural Cognitive Modifiability (SCM) and the idea of Mediated Learning Experience (MLE), the teacher acts as mediator, interposing themselves between stimuli the environment and the student. The work of the teacher observed indicates that the environment and the student. The work of the teacher observed indicates that she exerts her functions in teaching using pedagogical strategies which are found in her heart, precepts essential to mediation. This shows it is possible to associate the ideas of Feuerstein practices aimed at teaching students with severe mental disabilities.

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This article presents part of a study that analyzed the concepts, feelings and attitudes of children without disabilities about mental retardation and inclusion and evaluated the effects of an informative program that deals with the issue. The study included forty children from two first grade classrooms in a public school in Marília-SP. One classroom participated as a control group. All children underwent pre and post tests in the form of interviews on the subject and a scale of children's social attitudes towards inclusion was applied. The experimental group participated in the informative program, composed of thirteen weekly meetings, in which the limitations and possibilities of people with mental retardation, specialized care, their schooling and family and social aspects, were discussed, using various educational and recreational strategies. The data collected in the interviews were categorized and content analysis was conducted. With the scale, individual scores were obtained. Statistical calculations were performed to verify the significance of differences between groups. In this paper we discuss the data obtained with the scale which were crossed with interview data. The results of the interviews and the scale indicated several changes in children's attitudes towards inclusion, but relations between many of these data could not be statistically confirmed. These results indicate the importance of expanding the research on the relationship between the phenomena presented.

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Pós-graduação em Física - FEG

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We analyze the integrability properties of models defined on the symmetric space SU(2)/U(1) in 3 + 1 dimensions, using a recently proposed approach for integrable theories in any dimension. We point out the key ingredients for a theory to possess an infinite number of local conservation laws, and discuss classes of models with such property, We propose a 3 + 1-dimensional, relativistic invariant field theory possessing a toroidal soliton solution carrying a unit of topological charge given by the Hopf map. Construction of the action is guided by the requirement that the energy of static configuration should be scale invariant. The solution is constructed exactly. The model possesses an infinite number of local conserved currents. The method is also applied to the Skyrme-Faddeev model, and integrable submodels are proposed. (C) 1999 Elsevier B.V. B.V. All rights reserved.

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We use Hirota's method formulated as a recursive scheme to construct a complete set of soliton solutions for the affine Toda field theory based on an arbitrary Lie algebra. Our solutions include a new class of solitons connected with two different types of degeneracies encountered in Hirota's perturbation approach. We also derive an universal mass formula for all Hirota's solutions to the affine Toda model valid for all underlying Lie groups. Embedding of the affine Toda model in the conformal affine Toda model plays a crucial role in this analysis.

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Pós-graduação em Física - IFT