Estudo da contribuição do espalhamento nuclear não elástico de prótons na dose depositada em alvos com composição homogênea

Due the differences between interaction physics process with matter for protons and photons, the proton beam tomography (pCT) has some vantages to comparison with conventional tomography. Also it is confirmed that usually pCT has better dose distribution and highest contrast resolution. The pCT allow not only view the internal structure of an object without destroying it, but also directly measure of volume density of electrons. Also it is confirmed that usually pCT has better dose distribution and highest contrast resolution. At the same time, there are many scientific and technical aspects to a detailed study: the capacity and limitations of the pCT methods are not well clarified. Through computations, based on Monte Carlo Method was carried out a detailed study of the contribution of non-elastic nuclear spreading, and together was compared with an analytical model for the deflection angle and the lateral deflection of protons in the target volume. The programs used were SRIM 2006 code and MCNPX v.2.50 code

Estudo da contribuição do espalhamento nuclear não elástico na trajetória mais provável de prótons em alvo homogêneo composto de água

The Therapy with proton beam has shown more e ective than Radiotherapy for oncology treatment. However, to its planning use photon beam Computing Tomography that not considers the fundamentals di erences the interaction with the matter between X-rays and Protons. Nowadays, there is a great e ort to develop Tomography with proton beam. In this way it is necessary to know the most likely trajectory of proton beam to image reconstruction. In this work was realized calculus of the most likely trajectory of proton beam in homogeneous target compound with water that was considered the inelastic nuclear interaction. Other calculus was the analytical calculation of lateral de ection of proton beam. In the calculation were utilized programs that use Monte Carlo Method: SRIM 2006 (Stopping and Range of Ions in Matter ), MCNPX (Monte Carlo N-Particle eXtended) v2.50. And to analytical calculation was employed the software Wolfram Mathematica v7.0. We obtained how di erent nuclear reaction models modify the trajectory of proton beam and the comparative between analytical and Monte Carlo method

Estudo teórico da contribuição do espalhamento nuclear não elástico na trajetória de prótons de energias entre 50 e 250 MeV em materiais de interesse em radiologia: aplicação em tomografia com prótons

The goal of this work is to study the process of interaction of protons with matter through Monte Carlo simulation. For this purpose, it was employed the SRIM program (Stopping and Range of Ions in Matter ) and MCNPX (Monte Carlo N-Particle eXtended) v2.50. This work is going to support the development of a tomography system with protons. It was studied the interaction of proton with the follow materials: Polimethyl Mehacralate (PMMA), MS20 Tissue Substitute and water. This work employed energies in range of 50 MeV and 250 MeV, that is the range of clinical interest. The energy loss of proton after cross a material layer, the decreasing of its intensity, the angular and lateral de ection of incident beam, including and excluding nuclear interactions. This work is related with Medical Physics and Material Physics, like interaction of radiation with matter, particle transport phenomena, and the experimental methods in Nuclear Physics like simulation and computational by Monte Carlo method

Análise estrutural de aerogéis via espalhamento de luz a baixo ângulo

The sol-gel process is a method for obtaining vitreous or vitro-ceramic materials which, are prepared a sol and by drying the liquid phase. This technique has been used extensively for the preparation of glassy gels, films, fibers and particles from the hydrolysis and polycondensation reactions of metal alkoxides. The usual methods for drying are: evaporation drying (xerogels), freeze drying (criogéis) and via supercritical CO2 extraction (aerogels). In the present work, we studied the preparation of silica gels by the sol-gel process from the hydrolysis of alkoxides tetraethylorthosilicate (TEOS) and 3-glycidoxypropyltrimethoxysilane (GPTS). The hydrolysis was promoted from GPTS and TEOS in proportion (4: 1) under acidic conditions. The hydrolysis reaction was promoted inside a Becker at room temperature. After hydrolyses the prepared sol had pH 2, and kept under mechanical agitation for a period of 1 hour. In order to accelerate the polycondensation reaction, the pH was corrected to a value near 5 by slowly adding NH4OH. Then the sols were leaked in sealed polycarbonate containers and maintained for 20 days at 40°C for gelation. Silica aerogels were prepared via supercritical CO2 extraction of the wet gel at temperature and pressure higher than 31°C and 74 atm, in an autoclave specially developed for the process. The structural characteristics were studied in the dry gel (aerogel). Aerogels were then characterized by nitrogen adsorption and small angle light scattering. The nitrogen adsorption data were analyzed for the determination of the BET specific surface (SBET), the total pore volume Vp, the pore mean size (lP=4Vp/SBET), the particle mean size (lS) and the pore size distribution (PSD). And the data from small angle light scattering were analyzed to determine the correlation function (γ'), the area per unit volume (S/V), average pore size (l ) and the average particle size...

Espalhamento coulombiano relativístico próximo das condições de simetria de spin e pseudospin

Pós-graduação em Física - FEG

Estimativa da correção do coeficiente de retorno de esgoto sanitário em habitações com sistemas de aproveitamento de água pluvial: estudo de caso da cidade de Bauru (SP)

Pós-graduação em Engenharia Civil e Ambiental - FEB

Coeficiente de cultivo e lâminas de irrigação do maracujazeiro amarelo nas condições semiáridas

The study aimed to determine the coefficient of the yellow passion fruit cultivation and irrigation set capable of increasing crop productivity and quality of production in the environmental conditions of the semi-arid region of Piauí. The experiment was conducted in the Pilot Project for Fruit Crops Irrigated area in Santa Rosa, PI. We used a randomized block design with six treatments and four replications. Treatments (irrigation) were defined according to percentages of reference evapotranspiration (ETo): T1 25%, T2: 50%, T3: 75%, T4: 100%; T5: T6 and 125%: 150%. For monitoring water in the soil profile was used tensiometers. To determine the crop coefficient (Kc) used the water balance in the soil treatment based on 100% replacement of water. Morphological and physiological characteristics of yellow passion fruit were evaluated. The maximum yield of 27.052 kg ha-1 yr-1 was obtained by applying a water depth of 763.80 mm. The values of average fruit weight ranged from 0.207 kg (T6) and 0.159 kg (T1). The average kc obtained for the vegetative stage was 0.57 to 0.94 and flowering stage to fruiting phase 1.04. The water depth of greater efficiency comprise in the range of 75% and 100% ETo.

Estimativas da radiação difusa horária incidente em superfícies inclinadas com base na transmissividade atmosférica

Evaluated statistical equations estimates (based on radiometric fractions) of the hourly diffuse radiation incident on inclined surfaces for the North to 12.85, 22.85 and 32.85°, the climate and geographical conditions of Botucatu, SP. The database was generated from April/1998 to December/2007, with measures in the three tilted surfaces in different periods, but concomitant to the horizontal plane. In the validation of the equations were used indicative statistics MBE (mean absolute error), RMSE (square root mean square error) and index adjustment (d) for three inclinations and conditions of sky coverage. The increased angle of inclination of the surface led to increased scattering of hourly values for the coefficient of atmospheric transmissivity of diffuse radiation for inclined and horizontal surfaces. Estimates of diffuse radiation on the basis of hourly tilted horizontal global radiation occur for quadratic polynomial models, which adjust K'Dβ maximum values of between 0.14 and 0.30 for winter and summer when KTH varies between 0.40 and 0.66, indicating that energy, the highest values of diffuse radiation occur in partly cloudy sky conditions and / or partially open. The increase in atmospheric transmissivity decreases the performance of annual and monthly equations at all inclinations.

Termometria em chamas utilizando a técnica de espalhamento Rayleigh

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Quantificação de células dos túbulos seminíferos e rendimento da espermatogênese em cutias (Dasyprocta aguti) criadas em cativeiros

O presente estudo teve como objetivo avaliar o rendimento da espermatogênese de cutias criadas em cativeiro, por intermédio das razões encontradas entre tipos celulares do epitélio seminífero. Os resultados apontaram que o rendimento da espermatogênese da cutia dos nove aos quatorze meses de idade não chegou a um ponto de estabilização. O coeficiente de eficiência de mitoses espermatogoniais não aumentou com a idade. O rendimento meiótico, o rendimento geral da espermatogênese e o índice de células de Sertoli mostraram variações numéricas em função da idade, entretanto, não detectadas estatisticamente.