114 resultados para Tomografia por emissão de pósitrons
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Pós-graduação em Medicina Veterinária - FMVZ
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Pós-graduação em Biologia Geral e Aplicada - IBB
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The soil is one of the main C pools in terrestrial ecosystem, capable of storing significant C amounts. Therefore, understanding the factors that contribute to the loss of CO2 from agricultural soils is critical to determine strategies reducing emissions of this gas and help mitigate the greenhouse effect. The purpose of this study was to investigate the effect of soil tillage and sugarcane trash on CO2 emissions, temperature and soil moisture during sugarcane (re)planting, over a study period of 15 days. The following managements were evaluated: no-tillage with crop residues left on the soil surface (NTR); without tillage and without residue (NTNR) and tillage with no residue (TNR). The average soil CO2 emission (FCO2) was lowest in NTR (2.16 µmol m-2 s-1), compared to the managements NTNR (2.90 µmol m-2 s-1) and TNR (3.22 µmol m-2 s-1), indicating that the higher moisture and lower soil temperature variations observed in NTR were responsible for this decrease. During the study period, the lowest daily average FCO2 was recorded in NTR (1.28 µmol m-2 s-1), and the highest in TNR (6.08 µmol m-2 s-1), after rainfall. A loss of soil CO2 was lowest from the management NTR (367 kg ha-1 of CO2-C) and differing significantly (p<0.05) from the managements NTNR (502 kg ha-1 of CO2-C) and TNR (535 kg ha-1 of CO2-C). Soil moisture was the variable that differed most managements and was positively correlated (r = 0.55, p<0.05) with the temporal variations of CO2 emission from NTR and TNR. In addition, the soil temperature differed (p<0.05) only in management NTR (24 °C) compared to NTNR (26 °C) and TNR (26.5 °C), suggesting that under the conditions of this study, sugarcane trash left on the surface induced an average rise in the of soil temperature of 2 ºC.
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The aim of this study was to evaluate CO2 emission, canopy characteristics and herbage accumulation in pastures of pensacola bahiagrass under frequencies of defoliation. The experiment was conducted at the Universidade Estadual Paulista Julio de Mesquita Filho, Faculty of Agrarian Sciences and Veterinary of UNESP, Jaboticabal, São Paulo, Brasil. The experimental period was from May 3rd to July 26th 2012. The experimental area comprised 28 m² of pensacola bahiagrass (Paspalum notatum Flügge), divided into 10 plots for allocation of treatment (frequencies of defoliation = 2 or 4 weeks). The following variables were studied: canopy height, light interception, leaf area index, herbage accumulation, tiller density, CO2 emissions, soil temperature and moisture. The frequencies of defoliation in the months of May, June and July slightly affect pensacola bahiagrass characteristics. CO2, soil temperature and moisture are more associated to environmental conditions (months of evaluation) than to the frequencies of defoliation imposed to the canopies.
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Through the polymeric precursor method were synthesized samples Ca0.98Sr0.01X0.01TiO3 (X= Eu3+, Sm3+ and Pr3+), which under different heat treatments were obtained with levels of distinct structural order-disorder. The synthesized materials were characterized by X-ray diffraction, confirming the obtaining of ahomogeneous material with perovskite-type orthorhombic structure. This characterization allowed evaluating the average crystallite size of the samples that varies depending on the rare-earth ion. The results of photoluminescence emission confirmed the presence of this optical phenomenon at room temperature and its relationship to the level of order-disorder structural system. The photoluminescence emission is more intense in samples annealed at 500 ° C (independent on the dopant ion), the variation of the dopant influence on the emission intensity due to charge transfer between the host and emitting rare-earth ion, where the doped with Pr3+ ion has charge transfer more efficient and hence more intense emission in the photoluminescence. Another factor that favors the optical property of the samples is the charge compensation, as it contributes to the increase in structural disorder due to formation of Ca2+ vacancies.
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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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Pós-graduação em Agronomia (Produção Vegetal) - FCAV
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Almost forty years computed tomography (CT) has been one of the most powerful tools in diagnostic imaging. However, this modality delivers relatively high doses to their patients. It is known that the inappropriate use and unnecessary radiation may be associated with a significant risk of cancer, especially in pediatric patients. Moreover, the quality assurance in CT, provided and required by Portaria 453/98 and the guide of the RE 1016/05, ensures that the images generated by computer tomography provide reliable diagnostic information with doses as low as reasonably achievable. This research aimed to make the quality control (QC) of CT equipment; establish a better relationship between dose and noise on the image to protocols of skull CT according to the study of optimization proposed in 2005 by Daros; and assess the dose distribution in different cranial organs for protocols of adult and pediatric use in the routine of the Department of Diagnostic Imaging of HCFMB-UNESP. The equipment used for testing QC, optimization and dosimetry was a third generation tomograph GE Sytec 3000i
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Since discovery, computed tomography is a widely used diagnostic modality. However, this modality imparts relatively high doses to the patients and with fast technological advancement, it is necessary optimize the doses used and ensure the quality of the images through a quality assurance program. This work intended to compare Computed Tomography Dose Index (CTDIW) and effective dose with components of image quality: the Contrast-to-Noise Ratio (CNR) and Signal-to-Noise Ratio (SNR), and a quality factor (Q) deduced by the Rose model for two groups of computed tomography units. The first group was composed by equipments with 10 up to 16 slices and the second one presented 40 up to 320 slices detectors, for the protocols of head and abdomen. It was realized a comparison between different selectable parameters in the protocol of a Philips Brilliance 16, too. The results of the first group to CTDIW, effective dose, SNR and CNR showed variations of 28%, 33%, 37% and 32% respectively for head protocol, and 21%, 27%, 43% and 37% respectively for abdomen protocol. The results of the group 2 to CTDIW, effective dose, SNR and CNR showed variations of 15%, 26%, 36% and 34% respectively for the head protocol, and 8%, 13%, 50% and 60% respectively for abdomen protocol. The comparison between both groups demonstrated similar levels of doses impartation to patients though having so many different configurations, if the uncertainties associated with this measurement were considered. The results of the comparison between different parameters in the Philips Brilliance 16 scanner were in agreement with expected
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The computed tomography, devised by Godfrey Hounsfield and Allan Cormack, is in its fourth decade of the clinical use and has presented to be a very useful tool in the diagnosis of several pathologies. For this reason, its use is increasing each day, due to technological progress since its creation. Due to be more and more utilized, the equipment must be in good operating conditions, because it is subject to variance and wearing, damage the quality of diagnosis. To evaluate whether the performance of the scanner remains constant along the time and the dose received by the patient is within the desired limits, periodic tests of quality control must be performed. For this subject, the regulation 453 (June 01, 1998) was created, which determines the need of the implementation of a program for quality assurance (PGQ), where, in addition to the tests of quality control, are established the necessary measurements for the proper functioning of the equipment, generating a trustworthy diagnosis, reducing the dose for the patient and the costs. In this document, are presented tests of quality control carried out in hospitals of the city of Sao Paulo carried out together with the Technical Section of Applications by Imaging Diagnostic (STADI) of the Institute of Electrotechnics and Energy of the University of São Paulo (IEE/USP)
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Non-intrusive methods of diagnosis, such as spectral analysis of the radiation emitted by the system, have been used as a viable alternative for determining the temperature of combustion systems. Among them, the determination of temperature by natural emission spectroscopy has the advantage of requiring relatively simple experimental devices. Once Chemiluminescent species are formed directly in the excited state, the collection and recording of radiation emission spectrum is enough to determine the temperature (CARINHANA, 2008). In this study we used the process of making direct comparisons between the experimental spectra obtained in the laboratory from the plasma of alcohol, and the theoretical spectra plotted from a computer program developed at the IEAv. The objective was to establish a fast and reliable method to measure the rotational temperature of the radical C2*. The results showed that the temperature of the plasma, which in turn can be taken as the rotational temperature of the system, is proportional to the pressure. The temperature values ranged from ca. 2300 ~ 2500 K at a pressure of 19 mmHg to 3100 ~ 3500 K for the pressure of 46 mmHg. The temperature values are somewhat smaller when we consider the theoretical spectrum as a Lorentzian curve. The overlap of the spectra was better when using the profile curve, but still were not exactly superimposed. The solution to improve the overlap of the theoretical with the experimental spectra is the use of a curve that has the convolution of two profiles analyzed: Lorentzian and Gaussian. This curve is called the Voigt profile, which will also be implemented by programmers and studied in a next work
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The concern of the society with regard to the pollution if becomes each bigger and necessary time. This pollution generates damage for who is in contact, as much in economic terms how much in quality of life. The particulate matter is one of the main polluting the air, being the most harmful to human health, fine particles and ultra fine (below 2.5 μm in diameter). With this, this work had as objective to mensurar the pollution of air for material particulado through samplings in an urban center, in a siderurgical industry, a conventional coal bunker and a forest fire. The equipment used for the sampling of particles had been the DataRam4 (model DR 4000) and the Impactador de Andersen, both developed by company THERMO SCIENTIFIC. The first equipment uses a system of nefelometry and the second uses a gravimetrical system of sampling. During the carried through samplings, it can be observed in some cases the difficulty in the breath, badly be and low visibility that this type of pollutant can cause. In most cases the results were disturbing. In industry, conventional coal bunker and in the forest were measured values high concentration for particles smaller diameters. Peak concentrations issued were: 40,000 μg/m³, 182,000 μg/m³ and 400,000 μg/m³ for the industry, conventional coal bunker and forest, respectively. Already in the urban centre were satisfactory results, always staying within the limit allowed by the rules in force so far in the country
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The Biosusceptometry AC (BAC) is a research tool that has been extensively explored by the group Biomagnetism IBB-UNESP for monitoring of the gastrointestinal tract, its response to a known drug or in vivo performance of solid dosage forms. During this period the BAC, which has the characteristics of high sensitivity and low cost, has been developed primarily for recording signals contraction of activity and traffic human gastrointestinal tract. With the possibility of producing images with this instrumentation, it was possible to evaluate different situations in vitro and in vivo for physiological studies and pharmaceuticals. Considering the good performance of this system to produce planar images, the first aim of the BAC system tomography (TBAC) was to evaluate the system performance of BAC to produce tomographic images of phantoms ferromagnetic for a single channel system. All these applications were only possible because of their sensitivity to materials of high magnetic suscepitibility as ferrite, which allow to produce an electrical signal proportional to the variation of the magnetic flux generated by the presence of magnetic marker next to a first-order gradiometer. Measuring this variation at various points was possible to generate planar images that recently came to be produced in systems with multiple detectors, said multi-channels. From planar images, also producing tomographic images of simulators BAC bars in a system of 13 channels using only the center channel, with good results when applied to simple objects as one and two bars. When testing the resolution of the system with more elaborate forms the quality and resolution of images reconstructed is not satisfactory, which would be solved by increasing the spatial sampling rate and hence the acquisition time. The present system works with an acquisition time of about five hours. Whereas this system will be applied for in vivo experiments, the acquisition time became a ...