No description available.

No description available.

No description available.

O objetivo do presente estudo foi avaliar os fluxos das valvas aórtica (AO) e pulmonar (Pul) por meio de análise qualitativa (presença de regurgitações valvares e características do espectro avaliado) e quantitativa, com obtenção de parâmetros ecocardiográficos como velocidades máxima (V. Max.) e média (V. Me.), integral de velocidade (VTI), tempo de aceleração (TA) e ejeção (TE), volume sistólico (VS) e débito cardíaco (DC). Foram utilizados 30 cães, que após considerados clinicamente sadios por meio de exames físico, laboratoriais, eletrocardiográfico, ecocardiográfico (modos uni e bidimensional), radiográfico de tórax e mensuração da pressão arterial sistêmica, obtiveram-se os seguintes resultados para os referidos parâmetros: V.max. AO= 1,215 + 19,38 m/s; V. Me. AO= 0,722 + 0,08206 m/s; VTI AO= 0,141 + 0,02426m; TA AO= 38,80 + 11,29 ms; TE AO= 197,9 + 24,77 ms; VS AO= 29,63 + 14,59 mL; DC AO= 2,940 + 1,260 L/ min.; V. Max. Pul= 0,9457 + 0,1792 m/s; V. Me. Pul= 0,632 + 0,09960 m/s; VTI Pul= 0,1267 + 0,02324 m; TA Pul= 70,97 + 18,87 ms; TE Pul= 203,7 + 28,98 ms; VS Pul= 28,52 + 17,96 mL; DC Pul= 3,056 + 1,546 L/ min.. Em apenas três animais observou-se regurgitação pulmonar. Alguns parâmetros tiveram correlação negativa com a variável freqüência cardíaca (VTI AO, TE AO, VTI Pul, TA Pul, TE Pul, VS Pul), outros correlação positiva com a variável peso (VTI AO, TA AO, TE AO, VS AO, DC AO, VTI Pul, TE Pul, VS Pul, DC Pul), não sendo encontrada influência da variável sexo na maioria dos parâmetros avaliados. Na comparação entre os dois fluxos, observaram-se V. Max. AO e V. Me. AO maiores que V. Max. Pul. e V. Me. Pul., respectivamente, VTI AO maior que VTI Pul, e TA AO menor que TA Pul. Observada ainda uma correlação positiva e significativa entre VS AO e VS Pul e entre DC AO e DC Pul. / The purpose of this study was the evaluation of aortic (AO) and pulmonary (Pul) valves flow for the qualitative (valvar insufficiency presence, characteristic of flow profile) and quantitative analysis, obtaining this way chocardiographic parameters as: peak (PV) and mean (MV) velocities, velocity-time integral (VTI), acceleration (AT) and ejection (ET) time, stroke volume (SV) and cardiac output (CO). Thirty dogs were studied, and to be considered normal, physical, laboratory, electrocardiographic, echocardiographic (uni and bidimensional mode) exams, torax radiographs, and measurement of the blood pressure were accomplished, and the following echocardiographic parameters were obtained: AO PV= 1,215 19,38 m/s; AO MV= 0,722 + 0,08206 m/s; AO VTI= 0,141 + 0,02426m; AO AT= 38,80 + 11,29 ms; AO ET= 197,9 + 24,77 ms; AO SV= 29,63 + 14,59 mL; AO CO= 2,940 + 1,260 L/ min.; Pul PV= 0,9457 + 0,1792 m/s; Pul MV= 0,632 + 0,09960 m/s; Pul VTI= 0,1267 + 0,02324 m; Pul AT= 70,97 + 18,87 ms; Pul ET= 203,7 + 28,98 ms; Pul SV= 28,52 + 17,96 mL; Pul CO= 3,056 + 1,546 L/ min. The variable heart rate had negative correlation with AO VTI, AO ET, Pul VTI, Pul AT, Pul ET, Pul SV, and the variable weight had positive correlation with AO VTI, AO AT, AO ET, AO SV, AO CO, Pul VTI, Pul ET, Pul SV, Pul CO, differently from the variable sex, that had no influence on the evaluated parameters. The comparation of aortic and pulmonary valves flow demonstrated AO PV and AO MV higher than Pul PV and Pul MV, respectively, AO VTI higher than Pul VTI, and Pul AT higher than AO AT. The statistical evaluation also showed a strong and positive correlation between AO SV and Pul SV and between AO CO and Pul CO.

In modern communication systems, the rate of transmitted data is growing rapidly. This leads to the need for more sophisticated methods and techniques of implementation in every block of the transmitter-receiver chain. The weakest link in radio communications is the transmission channel. The signal, which is passed through it, suffers from many degrading factors like noise, attenuation, diffraction, scattering etc. In the receiver side, the modulated signal has to be restored to its initial state in order to extract the useful information. Assuming that the channel acts like a filter with finite impulse, one has to know its coefficients in order to apply the inverse function, which will restore the signal back to its initial state. The techniques which deal with this problem are called channel estimation. Noise is one of the causes that degrade the quality of the received signal. If it could be discarded, then the process of channel estimation would be easier. Transmitting special symbols, called pilots with known amplitude, phase and position to the receiver and assuming that the noise has zero mean, an averaging process could reduce the noise impact to the pilot amplitudes and thus simplify the channel estimation process. In this thesis, a novel channel estimation method based on noise rejection is introduced. The estimator takes into account the time variations of the channel and adapts its buffer size in order to achieve the best performance. Many configurations of the estimator were tested and at the beginning of the research fixed size estimators were tested. The fixed estimator has a very good performance for channels which could be considered as stationary in the time domain, like Additive White Gaussian Noise (AWGN) channels or slowly time-varying channels. AWGN channel is a channel model where the only distorting factor is the noise, where noise is every unwanted signal interfering with the useful signal. The properties of the noise are that it is additive, which means that the noise is superimposed on the transmitted signal, it is white so the power density is constant for all frequencies, and it has a Gaussian distribution in the time domain with zero mean and variance σ2=N. A slowly time varying channel refers to channel with coherence time larger than the transmitted symbol duration. The performance of a fixed size averaging estimator in case of fast time-varying channels is subject to the buffering time. When the buffering time is smaller or equal to a portion of the coherence time the averaging process offers better performance than the conventional estimation, but when the buffering time exceeds this portion of the coherence time the performance of the averaging process degrades fast. So, an extension has been made to the averaging estimator that estimates the Doppler shift and thus the coherence time, where the channel could be assumed as stationary. The improved estimator called Adaptive Averaging Channel Estimator (AACE) is capable to adjust its buffer size and thus to average only successive Orthogonal Frequency Division Multiplexing (OFDM) symbols that have the same channel distortions. The OFDM is a transmission method where instead of transmitting the data stream using only on carrier, the stream is divided into parallel sub-streams where the subcarriers conveying the sub-streams are orthogonal to each other. The use of the OFDM increases the symbol duration making it more robust against Inter-Symbol Interference (ISI), which the interference among successive transmitted symbols, and also divides the channel bandwidth into small sub-bandwidths preventing frequency selectivity because of the multipath nature of the radio channel. Simulations using the Rayleigh channel model were performed and the results clearly demonstrate the benefits of the AACE in the channel estimation process. The performance of the combination of AACE with Least Square estimation (AACE-LS) is superior to the conventional Least Square estimation especially for low Doppler shifts and it is close to the Linear Minimum Mean Square Error (LMMSE) estimation performance. Consequently, if the receiver has low computational resources and/or the channel statistics are unknown, then the AACE-LS estimator is a valid choice for modern radio receivers. Moreover, the proposed adaptive averaging process could be used in any OFDM system based on pilot aided channel estimation. In order to verify the superiority of the AACE algorithm, quantitative results are provided in terms of BER vs SNR. It is demonstrated that AACE-LS is 7dB more sensitive than the LS estimator.

Orienatdores: Luiz Carlos Zeferino, Cleide M. M. de Oliveira Franzin / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-11-01T13:59:23Z (GMT). No. of bitstreams: 1 Giacobbe_Marcelo_M.pdf: 8812176 bytes, checksum: 5473c79b25249564d1a4b291e390bb95 (MD5) Previous issue date: 1999 / Resumo: Existem dúvidas e contradições nas informações sobre o padrão vascular útero-placentário no primeiro trimestre da gestação. Com o objetivo de descrever as características vasculares útero-placentárias na gestação até 14 semanas, foi realizado um estudo clínico, descritivo, comparativo, utilizando a Dopplervelocimetria com mapeamento em cores endovaginal em 45 mulheres com gestação e 44 com aborto. Estudou-se a quantidade de vasos miometriais, o fluxo interviloso (FIV), os índices de resistência (IR), pulsatilidade (IP), as velocidades sistólica (VS) e diastólica (VD) das artérias miometriais. Para a análise utilizou-se o teste Qui-quadrado, teste de Wilcoxon e a análise de regressão linear múltipla. A quantidade de vasos miometriais foi menor na gestação que no aborto. A identificação de FIV foi mais freqüente no aborto e a gestação mostrou tendência de uma maior presença de FIV acima de 10 semanas de idade gestacional. As médias dos IR e IP da gestação foram maiores que as do aborto. Observou-se uma diminuição dos IR e IP nas artérias uterinas e arqueadas com a progressão da idade gestacional em ambos os grupos. A VS da uterina aumentou na gestação e esteve constante no aborto ao longo do primeiro trimestre. A VD da uterina apresentou aumento progressivo em ambos os grupos. As características vasculares observadas na gestação mostraram-se diferentes das do aborto na avaliação pela Dopplervelocimetria com mapeamento em cores com evidências de haver uma facilitação ao fluxo sangüíneo associado ao processo de falência gestacional / Abstract: There are questions and contradictions in the information about the uteroplacental vascular pattern during the first trimester of gestation. This study aimed to describe the uteroplacental vascular characteristics during gestation up to 14 weeks, and to compare them with the abortion ones in the same period. This clinical, descriptive and comparative study utilizes transvaginal color Doppler sonography in 45 women during gestation and in 44 after abortion. The quantity of myometrial vessels, the intervillous flow (IVF), the resistance index (RI), the pulsatility index (PI), and the systolic (SV) and diastolic (DV) velocities of the myometrial vessels were studied. Chi-square test, Wilcoxon test, and multiple linear regression were utilized for the analysis. The quantity of myometrial vessels was lesser in gestation than in abortion. The identification of IVF was more frequent in abortion and the gestation showed a tendency of a greater presence of IVF over 10 weeks of the gestational age. The means of RI and PI in the case of gestation were higher than the abortion ones. A decrease of RI and PI was observed in the uterine and the arcuate arteries with the gestational age progression in both groups. The SV of the uterine artery increased in the gestation group and was kept constant in the abortion one during the first trimester. The DV of the uterine artery presented a progressive increase in both groups. The vascular characteristics observed during gestation were found to be different than the abortion ones in the color Doppler sonography suggesting the evidence of a blood flow facilitation associated to the process of gestational failure / Mestrado / Tocoginecologia / Mestre em Tocoginecologia

No description available.

No description available.

Marine stratocumulus clouds cover extensive areas of the subtropical oceans and greatly influence Earth?s radiation by strongly reflecting the incoming solar radiation. The most climatologically pronounced stratus regime is located in the South-East Pacific. Drizzle is one of the several physical processes that affects the lifecycle and evolution of marine stratus by depleting the cloud liquid water and by stabilizing the marine boundary layer through evaporative cooling. In this study we use ship-borne radar observations from two innovative research cloud radars ? a Millimeter Cloud Radar (MMCR) (lambda=8 mm) and Frequency Modulated Continuous Wave (FMCW) radar (lambda=3 mm) to study the fallout of drizzle in the sub-cloud layer. Radar inter-comparison is used to perform calibration and quality control of the FMCW radar. The FMCW observations suffer no saturation and provide profiles of radar Doppler moments from the ship level to the cloud base. A lognormal drizzle drop size distribution is assumed and the parameters (N0, r0 and sigma x) are retrieved using the observed radar reflectivity and mean Doppler velocity profiles. The retrieved parameters are used to extract bulk parameters of the drizzle size distribution such as liquid water content, total number of droplets and rainfall rates at various heights within the sub-cloud layer (typically from 50-500 m). It is demonstrated that a simple evaporation model can be used to constrain the inversion from radar observables to drizzle size distribution parameters. The model output showed that the drizzle DSD is truncated at lower end due to the rapid evaporation of smaller drops and the logarithmic width of drizzle DSD is lower than the typically prescribed value of 0.35.

Medical ultrasound imaging is widely used to diagnose cardiacdiseases. The recent availability of real time 3D ultrasound posesseveral interesting challenges and opportunities, and the work of thisthesis is devoted to both challenges and opportunities. One of the key benefits of ultrasound imaging is that its images arereal time. This has been challenged with the recent introduction of 3Dimages, where the number of ultrasound beams is squared compared totraditional 2D images. One common way to alleviate this is byreceiving several closely spaced ultrasound beams from each pulsetransmission, which increases acquisition speed but affects the imagequality. Specifically, B-mode images are irregularly sampled and losespatial shift invariance while a bias in the Doppler velocityestimates causes a discontinuity in the velocity estimates in colorflow images. We have found that these artifacts can be reducedsignificantly by interpolation of the beamformed data from overlappingbeams, with the limitation of requiring at least twice the number ofbeamformers. We have also found that valvular regurgitation is one of thecardiac diseases that can benefit greatly from quantification ofseverity using 3D ultrasound. We have devised a modality that useshigh pulse repetition frequency 3D Doppler to isolate thebackscattered signal power from the vena contracta of a regurgitantjet. This measure is calibrated with a narrow reference beam insidethe jet to estimate the cross-sectional area of the vena contracta. Wehave validated this method with computer simulations, with an in vitrostudy and finally in vivo with 27 patients who had mitralregurgitation. We found that the cross-sectional area and regurgitantvolume of the vena contracta could be quantified without bias as long as the orifice was sufficiently large for a calibration beam tofit inside it. The severity of smaller regurgitations will beoverestimated, but this does not pose a clinical problem, as thesepatients can easily be identified by standard 2D Doppler examination and donot typically need further quantification. Finally, we have developed a new, fast 3D ultrasound simulation methodthat can incorporate anisotropic scattering from cardiac muscle cells. This approach is three orders of magnitudefaster than the most commonly used simulation methods, making it wellsuited for the simulation of dynamic 3D images for development and testingof quantitative diagnostic methods such as 3D speckle tracking andvolumetric measurements.