121 resultados para Moderação de nêutrons


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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Experiments using factorial arrangement of treatments are rather common and useful in agricultural research. The main advantage is the possibility of testing many hypotheses, allowing broader conclusions over different factors, studied simultaneously. Factorial arrangements are used to compare levels of each factor (main effects), and also to verify if the differences among levels of a given factor are dependent on the levels of the other factors (interacions). In the analysis of data from factorial experiments, difficulty is increased when additional treatments are included. Inclusion of one or more additional treatments is a quite common practice, since such treatments are usually taken as reference or standard for evaluation and comparasion of the remaimng treatments, or aiming complementary information. This increase of difficulty is however low, compared to the advantages. As in literature there are few references about the statistical analysis of factorial experiments with additonal treatments, and given straightforward use in experimentation, the objective of this work was the presentation of approach for the use of factorial experiments with additonal treatments trough the analysis of some examples using the SAS® software, with the corresponding theoretical development, obtaining the system of normal equations, estimators of the parameters and variance of contrasts among two treatment means. It is suggested that additional treatments should be used with caution. The analysis of variance of such kind of experiment was presented using matrix notation.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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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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O trabalho procura analisar o diário íntimo de José Vieira Couto de Magalhães, destacado político e intelectual do Brasil da segunda metade do século XIX, como registro etnográfico que ao mesmo tempo informa sobre questões prementes daquela época e evidencia o esforço de um indivíduo específico no sentido de conferir a si próprio um pouco de consistência, muito embora o diário esteja repleto de sinais de incompletude. A partir da noção do diário íntimo como prática cultural de constituição de si mesmo, faz-se uma discussão a respeito do efeito de verdade presente nesse tipo de escrita e as implicações para uso da fonte nas Ciências Sociais. Discute-se os temas mais evidentes ao longo do registro íntimo do autor: corpo, saúde e doença. Ao escrever sobre si mesmo, Couto de Magalhães evidencia o processo de educação das necessidades e das atividades corporais em muitos homens à época e, como ele dialogava com o ideal de família burguesa e higiênica que marcou o século XIX, registra a leitura de temas como homossexualismo, sonhos, casamento e medicina. O diário mostra ainda a preocupação do autor em encontrar equilíbrio entre corpo e mente, que lhe permitisse alcançar seu ideal de moderação, além do esforço em construir e legar ao futuro uma determinada imagem de si próprio.

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Este trabalho pretende estudar as figuras de pensamento da retórica clássica como uma das estratégias empregadas pelo enunciador para persuadir o enunciatário, para fazê-lo crer em seu discurso. Essas figuras retóricas dividem-se em dois grupos: as que se constroem a partir de procedimentos da sintaxe discursiva e as que se produzem a partir de mecanismos da semântica discursiva. As primeiras têm sua origem num desacordo entre as instâncias do enunciado e da enunciação, quando, por exemplo, se afirma algo no enunciado e se nega na enunciação, enquanto as segundas resultam de uma combinação, na sucessividade do sintagma, de figuras do discurso em disjunção. Com as figuras de pensamento, o enunciador diz sem ter dito, simula moderação para dizer de maneira enfática, finge ênfase para afirmar de maneira atenuada, apresenta uma nova combinação de figuras do discurso para levar o enunciatário a assumir o que lhe está sendo comunicado.

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The goal of this project is the reproduction, through the simulation code based on the MCNPX (Monte Carlo N-Particle eXtended) v2.50 method, of the proton beam interaction with the material, since, in proton therapy, only the particle ionization and excitation are analyzed and the occurence of nuclear interactive inelastic process are not considered. This work will help the development of studies concerning the contribution to the total dosis of secondary particles generated by nuclear interaction in proton therapy. They are: alpha particles ( ), deuterium(2H), tritium (3H), neutron (n) and helium (3He). A MS20 tissue substitute phantom was used as the target and the energy of the proton beams was within an interest range of 100 to 200MeV. With the results obtained, it was possible to generate graphics which allows the analysis of the dosis deposition relation with and without nuclear interaction, the percentage of secondary particles deposited dosis, the radial dispersion of neutrons in the material, the secondary particles multiplicity, as well as the relation between the secondary particles spectrum with the próton generated spectrum

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In the treatment plans in conventional Proton therapy are considered only the elastic interactions of protons with electrons and/or nuclei, it means, mainly ionization and coulomb excitation processes. As the energy needed to reach the deep tumors should be of several hundred of MeVs, certainly the nuclear inelastic channels are open. Only some previous studies of the contribution of these processes in the full dose have been made towards targets composed of water. In this study will be presented the results of the simulation of the processes of interaction of beams of protons in the range of 100-200 MeV of energy with a cylindrical phantom composed by striated muscle (ICRU), emphasizing in the contribution to total dose due to the deposition of energy by secondary particles alpha (α), deuterium (2H), tritium (3H), neutron (n) and hélio3 (3He), originated by nuclear inelastic processes. The simulations were performed by using the method of Monte Carlo, via the computer code MCNPX v2.50 (Monte Carlo N-Particle eXtended). The results will be shown demonstrated through the graphics of the deposited dose with or without nuclear interaction, the percentual of dose deposited by secondary particles, the radial dispersion of neutrons, as well as the multiplicity of secondary particles

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In proton therapy, the deposition of secondary particles energy originated by nuclear inelastic process (n, 2H, 3H, 3He and α) has a contribution in the total dose that deserves to be discussed. In calculations of plans implemented for routine treatment, the paid dose is calculated whereas the proton loses energy by ionization and or coulomb excitement. The contribution of inelastic processes associated with nuclear reactions is not considered. There are only estimates for pure materials or simple composition (water, for example), because of the difficulty of processing targets consisting of different materials. For this project, we use the Monte Carlo method employing the code MCNPX v2.50 (Monte Carlo N-Particle eXtended) to present results of the contribution to the total dose of secondary particles. In this work, it was implemented a cylindrical phantom composed by cortical bone, for proton beams between 100 and 200 MeV. With the results obtained, it was possible to generate graphics to analyze: the dose deposition relation with and without nuclear interaction, the multiplicity and percentage of deposited dose for each secondary particle and a radial dispersion of neutrons in the material

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Cosmic radiation has been identi ed as one of the main hazard to crew, aircraft and sensitive equipments involved in long-term missions and even high-altitude commercial ights. Generally, shields are used in spatial units to avoid excessive exposure, by holding the incident radiation. Unfortunatelly, shielding in space is problematic, especially when high-energy cosmic particles are considered, due to the production of large number of secondary particles, mainly neutrons, protons and alpha particles, caused by spallation reactions and quasi-elastic processes of the corpuscular radiation with the shield. Good parameters for checking the secondary particle production at target material are diferential cross section and energy deposited in the shield. Addition experiments, some computer codes based on Monte Carlo method show themselves a suitable tool to calculate shield parameters, due to have evaluated nuclear data libraries implemented on the algorithm. In view of this, the aim of this work is determining the parameters evaluated in shielding materials, by using MCNPX code, who shows good agreement with experimental data from literature. Among the materials, Aluminium had lower emission and production of secondary particles

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Poesias (1888), Olavo Bilac’s first book, contains Via Láctea, a collection of sonnets of love that, in frank rupture with the romantic sentimentalism, is characterized by neoclassical moderation and contention. Universalizing treatment of the themes results in concealment of the particular circumstances in which the poems were composed. It is intended in these few pages to evidence the links between these texts and known episodes of the courtship of the poet and Amélia de Oliveira, the sister of Alberto de Oliveira, with the goal of providing an understanding of Via Láctea as a “love diary” in which the painful stations of a frustrated passion were registered.