879 resultados para Skinfold thicknesses


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Our main purpose in this study was to quantify biological tissue in computed tomography (CT) examinations with the aim of developing a skull and a chest patient equivalent phantom (PEP), both specific to infants, aged between 1 and 5 years old. This type of phantom is widely used in the development of optimization procedures for radiographic techniques, especially in computed radiography (CR) systems. In order to classify and quantify the biological tissue, we used a computational algorithm developed in Matlab (R). The algorithm performed a histogram of each CT slice followed by a Gaussian fitting of each tissue type. The algorithm determined the mean thickness for the biological tissues (bone, soft, fat, and lung) and also converted them into the corresponding thicknesses of the simulator material (aluminum, PMMA, and air). We retrospectively analyzed 148 CT examinations of infant patients, 56 for skull exams and 92 were for chest. The results provided sufficient data to construct a phantom to simulate the infant chest and skull in the posterior anterior or anterior posterior (PA/AP) view. Both patient equivalent phantoms developed in this study can be used to assess physical variables such as noise power spectrum (NPS) and signal to noise ratio (SNR) or perform dosimetric control specific to pediatric protocols.

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This paper presents results describing the physical, mechanical, and thermal properties (melt flow index - MFI and oxidative induction time - OIT) of high density polyethylene and poly (vinyl chloride) after weathering exposure (6, 12, 18, and 30 months). The materials exposed were geomembranes of two thicknesses: 1.0 and 2.0 mm (PVC) and 0.8 and 2.5 mm (HDPE). The climate parameters (average) obtained were 25 degrees C (temperature), 93 mm (precipitation), 66% (relative humidity), and 19 MJ/m(2). day (intensity of global radiation). Some results showed, for instance, that the behavior of the geomembranes changed after the exposures. A few minor variations in physical properties occurred. The density and thickness, for instance, varied 0.5-1.0% (average) for both the PVC and HDPE geomembranes. The mechanical properties changed as a function of the period of exposure. In general, some decreases were verified by the deformation of PVC. The samples became more rigid. In contrast, HDPE geomembranes became more ductile. Despite the variations in elasticity, some increases in deformability were verified. An MFI test showed some degradation in HDPE geomembranes. OIT tests revealed small values for both intact and exposed samples.

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Pós-graduação em Fisiopatologia em Clínica Médica - FMB

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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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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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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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Purpose: This study aimed to investigate the influence of ceramic thickness and shade on the Knoop hardness and dynamic elastic modulus of a dual-cured resin cement.Materials and Methods: Six ceramic shades (Bleaching, A1, A2, A3, A3.5, B3) and two ceramic thicknesses (1 mm, 3 mm) were evaluated. Disk specimens (diameter: 7 mm; thickness: 2 mm) of the resin cement were light cured under a ceramic block. Light-cured specimens without the ceramic block at distances of 1 and 3mm were also produced. The Knoop hardness number (KHN), density, and dynamic Young's moduli were determined. Statistical analysis was conducted using ANOVA and a Tukey B rank order test (p = 0.05).Results: The bleaching 1-mm-thick group exhibited significantly higher dynamic Young's modulus. Lower dynamic Young's moduli were observed for the 3-mm-thick ceramic groups compared to bleaching 3-mm-thick group, and no difference was found among the other 3-mm groups. For the KHN, when A3.5 3-mm-thick was used, the KHN was significantly lower than bleaching and A1 1-mm-thick ceramic; however, no difference was exhibited between the thicknesses of the same shade.Conclusions: The dual-cured resin cement studied irradiated through the 1-mm-thick ceramic with the lightest shade (bleaching ceramic) exhibited a better elastic modulus, and there was no effect in KHN of the resin cement when light cured under different ceramic shades and thicknesses (1 and 3 mm), except when the A3.5 3-mm-thick ceramic was used.Clinical Significance: Variolink II irradiated through ceramic with the lowest chroma exhibited the highest elastic modulus; therefore, the light activation method might not be the same for all clinical situations.

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Technology is growing interest in the use of composites, due to the requirement of lighter materials and more resistant, factors essential to meet the project specifications and reduce the operational cost. In the production of high performance structural composites, considering the aerospace criteria, the domestic industry has shown interest in the process of resin transfer molding (RTM) for reproducibility and low cost. This process is suitable for producing components of polymeric composites with relatively simple geometries, consistent thicknesses, high quality finish with no size limitations. The objective of this work was machined carbon steel to make a matched-die tooling for RTM and produce two composite plates of epoxy resin and carbon fiber fabric with and without induced discontinuities, which were compared towards their impregnation with ultrasound, their properties via tensile tests and thermal analysis. In ultrasonic inspection, it was found good impregnation of the preform of both composites. In the thermal analysis it was possible to check the degradation temperature of the composites, the glass transition temperature and it was found that the composites showed no effective cure cycles, but presented good performance in the tensile test when compared with aluminum alloy 7050 T7451 . The results showed that the injection strategy was appropriate since the laminate exhibited a good quality for the proposed application

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The quality assurance control program (QACP) in clinical radiology is very important to acquire, image quality, patient dose reduction and cost for the institution. The verification of the real tension on the x ray tube, it is one of many parameters that may be determined on a QACP. This act on image quality as absorbed dose in patient. Once proved the importance of this fact, this study come up with the determination of tension to any X ray tube used on medical routine, on quick, safe and low cost manner. To reach the aim of this study, the methodology consisted on measuring expose rates (ER) using different thicknesses of copper (Cu) plates like filters and relating these results with Half Layer Value (HLV). Afterwards, the HLV was associated to real tension that was acquired with kilo voltage of peak (kVp) measurers used on clinical routine. So walking in this path, when performed the ER, on any X ray tube, it’s possible acquire the HLV and consequently the real kVp, considering measures obtained before, on the methodology of kVp estimative development

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Paediatric diagnostic radiology can be considered as a separate specialty and with distinct characteristics of the radiology applied in adult patients. This in reason of the variability in the anatomical structures size and bigger sensitivity of tissues. The literature present in its majority methodologies for segmentation and tissue classification in adult patients, and works on tissue quantification are rare. This work had for objective the development of a biological tissue classifier and quantifier algorithm, from histograms, and that converts the quantified average thickness of these tissues for its respective simulator materials. The results will be used in the optimization process of paediatrics images, in future works, since these patients are frequently over exposed to the radiation in the repeated attempts of if getting considered good quality radiographic images. The developed algorithm was capable to read and store the name of all the archives, in the operational system, to filter artifacs, to count and quantify each biological tissues from the histogram of the examination, to obtain the biological tissues average thicknesses and to convert this value into its respective simulator material. The results show that it is possible to distinguish bone, soft, fat and pulmonary tissues from histograms of tomographic examinations of thorax. The quantification of the constituent materials of anthropomorphic phantom made by the algorithm, compared with the data of literature shows that the biggest difference was of 21,6% for bone. However, the literature shows that variations of up to 30% in bone thickness do not influence of significant form in the radiographic image quality. The average thicknesses of biological tissues, quantified for paediatrics patients, show that one phantom can simulate patients with distinct DAP ranges, since variations... (Complete abstract click electronic access below)

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In building the structural part that primarily supports loads, wich then makes the effort to transfer the remaining is the slab wich the forwards the effort to beam and then to the pillars. As architectural plans requir more complex, the great the spans, eg cases of slabs garages building, since it is not very useful when you put many pillars, over the number of vacancies. Major spans in dealing with solid slbs mean greater thicknesses.....