121 resultados para Local Variation Method
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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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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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This paper aims to contribute to the three-dimensional generalization of numerical prediction of crack propagation through the formulation of finite elements with embedded discontinuities. The analysis of crack propagation in two-dimensional problems yields lines of discontinuity that can be tracked in a relatively simple way through the sequential construction of straight line segments oriented according to the direction of failure within each finite element in the solid. In three-dimensional analysis, the construction of the discontinuity path is more complex because it requires the creation of plane surfaces within each element, which must be continuous between the elements. In the method proposed by Chaves (2003) the crack is determined by solving a problem analogous to the heat conduction problem, established from local failure orientations, based on the stress state of the mechanical problem. To minimize the computational effort, in this paper a new strategy is proposed whereby the analysis for tracking the discontinuity path is restricted to the domain formed by some elements near the crack surface that develops along the loading process. The proposed methodology is validated by performing three-dimensional analyses of basic problems of experimental fractures and comparing their results with those reported in the literature.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Background: Duplex ultrasound scanning (DUS) is the method of choice for diagnosis of deep vein thrombosis (DVT). However, only a few studies have performed prospective serial DUS after an acute episode of DVT to assess its evolution. This study aimed to report our experience using DUS combined with a thrombosis score (TS) and a newly proposed vein diameter variation index (VDVI) to evaluate the rate of resolution of DVT by assessing and quantifying the early stages of vein recanalization in proximal vein segments within 6 months after an episode of acute lower extremity DVT.Methods: Twelve patients with first episode of acute lower extremity DVT confirmed by DUS as occurring in <= 10 days after the onset of venous thrombosis symptoms were followed up prospectively for 6 months. TS and VDVI were calculated at 1, 3, and 6 months to assess vein recanalization. Intra-thrombus arteriovenous fistula formation was also investigated and related to the recanalization process.Results: Seven (58%) women were included, with a total cohort median age of 53.5 +/- 19 years. The left lower extremity was affected in 7 (58%) patients. DVT was diagnosed in 55 proximal vein segments. All patients had proximal DVT, with involvement of the external iliac, femoral, and popliteal veins. After 6 months, there was a significant decrease in TS and increase in VDVI (P < 0.001) in all proximal vein segments assessed, indicating thrombus regression. The more distal the DVT was, the faster was the VDVI increase, with most popliteal veins being recanalized at 3 months (P < 0.001). Intra-thrombus arteriovenous fistula was identified in 50% of patients at 1 month while on anticoagulation.Conclusions: The combined use of two different DUS-based assessment tools, TS and the proposed VDVI, provided an effective method to prospectively assess vein recanalization rates after an episode of acute lower extremity DVT in this series of patients and may allow a correct evaluation of DVT and its resolution or progression.
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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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A very simple method based on electrical conductivity and pH measurements was proposed for assessing reactivity of pozzolans. Calcium hydroxide: pozzolan water suspensions were monitored by means of measurements of electrical conductivity and pH values. In these suspensions, Ca(OH)(2) in solid state was initially present, being them, thus, saturated in this reagent. Three testing temperatures were selected (40, 50 and 60 degrees C). In the experiments carried out, calcium hydroxide was suspended in deionized water for yielding a lime saturated suspension. The addition of siliceous pozzolan (two types of rice husk ash RHA and two types of densified silica fume DSF were tested) to the saturated lime suspension can produce the unsaturation of the system, depending on the testing time, testing temperature and reactivity of pozzolan. When unsaturation was reached, the loss of electrical conductivity was higher than 30% and the variation of pH was higher than 0.15 units. These threshold values were selected for characterizing the reactivity of pozzolans by means of a proposed template, classifying the pozzolan in three different reactivity levels.
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Individuals of the species Turdus leucomelas are adapted to live in environments already modified by humans, thus obtaining reproductive success in their nesting in vegetation, as well as built their nests in human buildings. Nests found in buildings are often less camouflaged, making them more exposed to predators compared to nests built in vegetation; however the nests built buildings are common, indicating a possible advantage associated with these nests. By means of this idea if was assumed that a possible advantage to this construction in buildings is linked to a change in variation in the internal temperature of the nest during incubation and development of pups until they leave their nests. Accordingly, with the aid of iButtons and TidBits (temperature data loggers), the present study aimed to analyze the influence of the nesting site on how the temperature is kept, and how it changes in the microenvironment in which the nest is inserted, indicating potential benefits associated with that choice. In the samples found with the vegetation, temperature data showed a pattern of temperature of the microenvironment of the nests is not very stable, varying with ambient temperature, whereas in the samples found with the human constructions, the temperature data showed a pattern of temperature microenvironment nests more stable for a long time. When comparing the two environments which they settled nests, as well as the different times of day (daytime and nighttime), how the temperature was kept and pattern of change within the nest was significantly different (F=43.85, p<0.001), with higher and more constant internal temperatures in nests installed in construction, compared to vegetation. When observing periods of the day, it was found that in both environments the temperature inside the nest reached higher values and higher than the environment at night, coinciding with the rest of the female at night. Data may suggest changes in the...
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In this paper we presente a classification system that uses a combination of texture features from stromal regions: Haralick features and Local Binary Patterns (LBP) in wavelet domain. The system has five steps for classification of the tissues. First, the stromal regions were detected and extracted using segmentation techniques based on thresholding and RGB colour space. Second, the Wavelet decomposition was applied in the extracted regions to obtain the Wavelet coefficients. Third, the Haralick and LBP features were extracted from the coefficients. Fourth, relevant features were selected using the ANOVA statistical method. The classication (fifth step) was performed with Radial Basis Function (RBF) networks. The system was tested in 105 prostate images, which were divided into three groups of 35 images: normal, hyperplastic and cancerous. The system performance was evaluated using the area under the ROC curve and resulted in 0.98 for normal versus cancer, 0.95 for hyperplasia versus cancer and 0.96 for normal versus hyperplasia. Our results suggest that texture features can be used as discriminators for stromal tissues prostate images. Furthermore, the system was effective to classify prostate images, specially the hyperplastic class which is the most difficult type in diagnosis and prognosis.
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A monitoring network of atmospheric electric field covering the Vale do Paraiba region was implemented. The sensors were located on different sites with different altitude and geographic topology. The present work reports the study carried on those sensors in order to verify the necessity of using some correction factor to the measured local electric field intensity due to effects of local environment. The measurements were done in continuous 24 hours per day with the data recorded on registers in each device accumulating information during a period of four months. The relation between the electric field values by each sensor was compared to the reference located on Sao Jose dos Campos city using the same period. In a graphical analysis using the local field intensity and the reference, the data were fitted to a straight line obtained by minimum square method. Variation up to 95% was observed between the field values in some sensors. Another method was proposed, comparing the mean values of the electric field in a function of time. The variation in some sensors reached up to 133%. We conclude that the variations are due to local atmospheric conditions and no correction factor is required on the electric field sensors
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Nowadays, articaine hydrochloride (ATC) is a local anesthetic widely used in dental procedures, but its side effects include paresthesia and nerve injury. Alginate/chitosan nanoparticles (AG/CSnano) can be used as carrier for drugs, overcoming the problems. The aim of this work was to evaluate the factors (Calcium/alginate [Ca2+:AG] and Chitosan/alginate [CS:AG] mass ratios) influence on the average size, polydispersity index, zeta potential and encapsulation efficiency of ATC. AG/CSnano containing ATC were prepared by ionic pregelation method. A three-level factorial design was carried out and the factors varied were Ca2+/AG mass ratio and CS/AG mass ratio. There were obtained nanoparticles with size range of 340–550 nm and polydispersity index between 0.2 and 0.5, zeta potential range –19 and –22 mV and encapsulation efficiency of ATC in AG/Csnano between 22 and 45%. According to the results, the average size, polydispersity index and encapsulation efficiency were significantly affected to the variation of Ca2+/AG and CS/AG mass ratio, but the zeta potential didn't change significantly with factor variations. The factorial design showed it was possible to identify formulations that presented better results for the parameters measured. The factor chosen for the suitable formulations was the encapsulation efficiency. Through this parameter, one formulation was chosen with highest encapsulation efficiency of ATC and presented good colloidal stability parameters aiming future clinical applications.
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The local anesthetic articaine (ATC) is widely used in dentistry; however, its side effects can include paresthesia and nerve injury. Polymeric nanocapsules (PN) can be used as carriers for drugs, and help to reduce undesirable symptoms. The objective of this study was to evaluate the influence of different factors on the average size, polydispersion, and encapsulation efficiency of PN containing ATC. Poly(ε-caprolactone) (PCL) nanocapsules containing ATC were prepared by the oil-in-water emulsion/solvent evaporation method. The final ATC concentration was 2%. The preparation conditions were optimized using a central composite blocked cube-star design to investigate the influence of two variables at five levels, with 22 factorial points (–1 and +1), two replicates of the central point, 2×2 axial points (–1.414 and +1.414), and an orthogonal distribution, resulting in 10 experiments. The factors varied were the PVA concentration and the sonication time. The nanocapsules showed a satisfactory size range, a polydispersivity index less than 0.2, and high encapsulation efficiency. The values of the factors had no significant influence on either average size or polydispersion, although the encapsulation efficiency was significantly influenced by the sonication time. Improved formulations were identified using the central composite design, which revealed that the main consideration in selecting a suitable formulation was the encapsulation efficiency. Two of the formulations showed both high encapsulation efficiency and colloidal characteristics appropriate for the route of administration.