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A rapidly scanning directionally-sensitive three-velocity - component laser Doppler anemometer has been developed. It permits scans through 3-dimensional flows to obtain space-time velocity information. Since it has lower signal-averaging bias than pointwise measurements, only short record times are required to obtain sufficient data for statistical averages and, hence, it enables rapid mapping of the U, V, and W velocities in such flows. A flexible optical system allows for easy variation of the fringe spacings as well as the location and the size of the measurement volume. The optical paths are equalized without use of any additional optical components. A Ronchi Ruling is employed to create a horizontal stationary fringe pattern, and a dual Bragg cell is used to produce sets of moving vertical fringes. It is also shown that a scheme proposed by other workers, relying on a fringe pattern moving in the on-axis direction, will not work. The Doppler frequency is independent of the position of the receiving optics, and only one photomultiplier tube is needed to receive the signals for all three velocity components. Measurements made on a stationary solid object as well as in a dispersion of particles in water show that signals with low noise level and high fringe visibility are obtained. / M.S.

A theoretical method for extracting the rotational degrees of freedom from a reconstructed three-dimensional velocity field has been developed. To extract the angular velocities the curl of the translational velocities must be performed. The three-dimensional velocity field is to be equally spaced so that the DFT-IDFT technique of taking partial derivatives of the translational velocities is used. A program was written in C along with MATLAB® which performed the theoretical calculations. Two proposed methods of experimentally verifying the angular velocity data is developed using a Kistler translational/angular piezobeam accelerometer to compare against the DFT-IDFT partial derivative technique for calculating the angular velocities. / Master of Science

This thesis suggests a formulation for updating physically meaningful parameters in analytical finite element(FE) models using scanning laser Doppler vibrometer(SLDV) dynamic response data. The update formulation is demonstrated in several computer simulations. The formulation is the result of incorporating an analytical FE model into an experimental model. The experimental model efficiently utilizes SLDV data to fully exploit the instrument's capability to automatically make measurements at many locations. The data in the experimental model is posed in a manner consistent with an analytical FE model's representation for harmonic response, simplifying comparison between the two. The experimental model, which uses finite element shape functions as a basis for a least squares fit to the data, can be solved to give a velocity field based only on that data. The function resulting from inserting the analytical model into the experimental model is an expression of the prediction error of the FE model as compared to the test data. This function is minimized using a quasi-Newton optimization routine, reducing the error and resulting in an updated model. Computer simulations of the update algorithm indicate that: 1. Analytically supplied derivatives and variable scaling are required by the optimization routine to consistently converge, 2. The percentage error of updated parameters falls within two standard deviations of the data's percentage error, 3. Error in the position of the laser results in the update algorithm's failure, and, 4. Error in the parameters not included in the update will appear as error in the updated parameters' solution. / Master of Science

Data collected with a three-component laser Doppler anemometer system is used to investigate velocity bias. The data is collected in the viscous layer of a fully developed turbulent open water flow at a Reynolds number of 14,766 based on the flow depth. The data collected at a relatively low data rate is analyzed using different correction methods including: straight forward arithmetical averaging, inverse velocity and transit time weighting. The streamwise mean velocity components, the RMS values and the kinematic Reynolds stress are computed using the various weighting methods and are compared to a three-component inverse velocity bias correction model which is taken to represent the "true" values. The three-component inverse velocity bias correction results are in general accordance with the expected behavior in open channel flow and are comparable to the results reported by other researchers employing different experimental techniques. The results of this study show that the bias is sensitive to the correction method used and the theory that the mean streamwise velocity error (without correction) is proportional to the square of the turbulence intensity is confirmed experimentally. Averaging the data without correcting it produced the largest bias while the results from the different inverse velocity techniques were approximately the same although the level of the bias varied with the turbulence variable that was analyzed. As reported in the literature, the transit time weighting method requires accurate determination of the residence time. The relatively poor performance of the transit time method in the present comparison is attributed to the poor accuracy in the measurement of the residence time. / Master of Science

O sinal de fluxo cutâneo obtido via fluxometria Laser Doppler (SFLD) tem flutuações de baixas frequências que estão relacionadas a mecanismos de controle do fluxo microvascular. Análises espectrais, via transformada de Fourier e transformada de wavelet, têm sido usadas para correlacionar as flutuações de SFLD com os seguintes mecanismos de controle de fluxo: metabólico, metabólico NO-dependente, neurogênico e miogênico, nos respectivos intervalos de frequência 0,005-0,0095 Hz, 0,0095-0,02 Hz, 0,02-0,05 Hz e 0,05-0,15 Hz. A potência do sinal, em cada intervalo de frequência, geralmente é usada como uma medida da atividade do mecanismo de controle microvascular relacionado. Uma vez que os métodos usados de análise são espectrais, as características das flutuações do SFLD, em cada intervalo de frequência, no domínio do tempo são desconhecidas. Como consequência, há ausência de critérios objetivos para medir adequadamente, em cada intervalo de frequência, os parâmetros hemodinâmicos relacionados. O objetivo deste trabalho foi caracterizar e quantificar flutuações temporais, espaciais e espaço-temporais do SFLD em cada faixa de frequência, usando um método no domínio do tempo. Os fluxos basais (320C) e termicamente estimulados à (420C) das regiões volares de antebraços de 20 voluntários saudáveis foram coletados em duas regiões próximas e analisados. As análises dos dados obtidos indicam que janelas temporais pequenas (1 minuto) são aceitáveis para a quantificação do fluxo médio, e que janelas temporais maiores são necessários para quantificar as flutuações de fluxo. A análise espaço-temporal revelou uma forte correlação entre sinais (em todas as bandas, exceto na banda B5) das duas regiões investigadas, durante longos intervalos de tempo, quando as duas regiões estudadas foram termicamente estimuladas, e menor variabilidade intragrupo quando comparada à obtida para os valores médios das flutuações, sugerindo que o intervalo de tempo de correlação é um parâmetro promissor para estudar mecanismos de controle do fluxo microvascular. / The laser Doppler flow signal from the skin (LDFS) has low-frequency fluctuations which are related to microvascular mechanisms of flow control. The Fourier and the wavelet spectral analysis has been used to correlate fluctuations in the LDFS with the metabolic, metabolic NO-dependent, neurogenic and myogenic mechanisms of control in the frequency intervals 0.005-0.0095 Hz, 0.0095-0.02 Hz, 0.02-0.05 Hz and 0.05-0.15 Hz, respectively. The signal power, in each frequency interval, is generally used as a measure of the activity of the related mechanism of microvascular control. Since spectral analysis methods have been used, the time-domain characteristics of the fluctuations in the LDFS in each frequency interval are unknown. As a consequence, there is a lack of objective criteria to properly measure, in each frequency interval, the related hemodynamic parameters. The aim of this work was characterizing and quantifying temporal, spatial and spatial-temporal fluctuations in the LDFS in each frequency band, using a time-domain method. Baseline (320C) and thermally stimulated (420C) LDFS of volar forearms from 20 healthy volunteers were collected from two close regions and analyzed. The data obtained indicate that short-time windows (1 minute) are acceptable for quantifying the mean flow, and that larger time-windows are needed for quantifying the flow fluctuations. The spatialtemporal analysis revealed strong correlations between signals (all bands, except B5) from the two investigated regions, during large time intervals when thermally stimulated, and lower intragroup variability than the ones obtained for the mean values of fluctuations, suggesting that the time interval of correlation is a promising parameter for studying mechanisms of microvascular flow control.

A quimioterapia e a radioterapia são modalidades terapêuticas não cirúrgicas aplicadas a pacientes com neoplasias malignas. A mucosite oral (MO) é uma inflamação da mucosa oral decorrente destas terapias antineoplásicas, manifestando-se por atrofia, inchaço, eritema e úlcera, comprometendo a qualidade de vida. A patogênese da mucosite oral envolve uma cascata de eventos de natureza inflamatória que culminam em alterações no epitélio e no tecido conjuntivo. Dentre estas modificações destacam-se as alterações na microvascularização, as quais precedem as alterações epiteliais na mucosa oral induzida por radiação e pelos agentes quimioterápicos. A Fluxometria Laser Doppler é um método não invasivo que permite avaliar parâmetros clínicos da microcirculação através do monitoramento do fluxo continuamente, em tempo real. O objetivo deste estudo foi avaliar a fluxo sanguíneo na região geniana em pacientes sob radioterapia de cabeça e pescoço ou quimioterapia através da técnica de Fluxometria Laser Doppler e comparar a graduação de mucosite oral e dor com dados obtidos na avaliação do fluxo sanguíneo. Este estudo observacional e prospectivo teve uma amostra de 14 pacientes oncológicos que foram avaliados antes do início da terapia antineoplásica e durante a fase intensiva da radioterapia de cabeça e pescoço ou quimioterapia, em 7 momentos. Para esta avaliação foi utilizado o Fluxômetro Laser Doppler para o registro do fluxo sanguíneo; as escalas da OMS (Organização Mundial da Saúde) e OMAS (Oral Mucositis Assessment Scale) para a avaliação do grau de mucosite; e Escala Visual Analógica (EVA) para a avaliação da dor em mucosa oral. Ao se comparar o fluxo sanguíneo nos tempos T1, T2, T3, T4, T5 e T6 com o T0, para os pacientes submetidos a radioterapia de cabeça e pescoço, não houve diferença estatística (p>0,05). Para os pacientes sob quimioterapia, houve diferença estatística nos tempo T1 (p=0,033) e T6 (p=0,043). Houve correlação positiva fraca entre as escalas para avaliação de mucosite oral (OMS (p=0,031) e OMAS (p=0,009)) e o fluxo sanguíneo. Não houve grau de relação entre dor induzida por mucosite oral e fluxo sanguíneo (p>0,05). A Fluxometria Laser Doppler permitiu a observação da dinâmica microvascular da região geniana da face em pacientes sob terapia antineoplásica e com risco de desenvolvimento de mucosite oral. Nos pacientes sob quimioterapia, houve aumento de perfusão cutânea na face nos tempos iniciais da MO, com progressiva redução do fluxo no decorrer do ciclo de quimioterapia. / Chemotherapy and radiotherapy are non surgical therapeutic modalities to malignancies. Oral mucositis is a inflammation of the oral mucosa due to these cancer therapy, typically manifesting as atrophy, swelling, erythema and ulceration compromising the quality of life. The pathogenesis of oral mucositis (OM) involves a cascade of inflammation events that result in changes in the epithelial layer and connective tissue, including microvascular modifications. These modifications precede epithelial changes induced by radiation therapy and chemotherapeutic agents, thereby modifications in blood flow may be a predictive factor of the severity of oral mucositis. Laser Doppler flowmetry (LDF) is a non invasive method enabling the monitoring of microvascular blood flow continuously in real time. The aim of this study was to evaluate the blood flow in the genius region in patients undergoing head and neck radiation and/or chemotherapy by Laser Doppler Flowmetry and compare the degree of oral mucositis and pain with data obtained in the evaluation of blood flow. This prospective observational study had a sample of 14 oncologic patients who were evaluated before and during the intensive phase of head and neck radiotherapy or chemotherapy in 7 times. For this evaluation, we used the Laser Doppler Flowmeter to measure blood flow; WHO scale (World Health Organization) and OMAS (Oral Mucositis Assessment Scale) for assessing the severity of mucositis; and Visual Analogue Scale (VAS) for pain assessment in oral mucosa. When we compare blood flow in T1, T2, T3,T4, T5 and T6 with T0, for patients undergoing radiotherapy for head and neck, there was no statistical difference (p> 0.05). For patients undergoing chemotherapy, there was a statistical difference in time T1 (p = 0.033) and T6 (p = 0.043). There was a weak positive correlation between the scale for assessing oral mucositis (WHO (p = 0.031) and OMAS (p = 0.009)) and blood flow. There was no relation degree pain induced oral mucositis and blood flow (p>0.05). Laser Doppler flowmetry allowed the observation of microvascular dynamics in the genian region of the face in patients undergoing antineoplastic therapy and risk of developing mucositis. In patients undergoing chemotherapy, there was an increase of skin perfusion in the face in the early days of the OM, with progressive reduction in flow during the course of chemotherapy.

[Truncated abstract] Purpose: To improve our ability to interpret and validate Heidelberg Retina Flowmeter (HRF) flow images by recording flow measurements from specific regions of the retinal vasculature in in-vitro and in-vivo eye models in which retinal blood flow can be manipulated. Methods: The first experiments utilised an isolated perfused pig eyes perfused with a 50%/50% Krebs/RBC solution at known flow rates ranging from zero to 300 μl/min. After HRF image acquisition, the retinal vasculature was perfused with fluorescein isothiocyanate (FITC), for fluorescence microscopy. Using the standard HRF software and a 10×10 pixel measurement window, flow rates were measured from a retinal artery, vein, arteriole, venule, and the retinal capillary bed and a capillary-free-zone. The relationship between HRF measured flow and perfusion flow in the different measurement regions was determined. For the second study, HRF flow images were acquired at retinal sites in Brown Norway rats over a range of focus levels before and after cessation of retinal blood flow by laser-induced central retinal artery occlusion. Using the 10×10 pixel and 4×4 pixel measurement windows, HRF measured flow was performed in retinal artery, vein, arteriole, capillary and choroidal vessel locations. The relationship between HRF measured flow and focus depth was determined for each location before and after central retinal artery occlusion. At the conclusion of each experiment the effect of reduction of systemic blood pressure (by exsanguination) on HRF flow measurements in choroidal vessels and in locations without visible choroidal vessels was assessed. Finally, HRF flow measurements were acquired after euthanasia, to determine the HRF flow signal which was still present under zero biological flow conditions (the zerooffset). Results: In the isolated perfused pig eye experiments it was found that the HRF flow response varied according to vascular location. At zero perfusate flow, HRF flow was consistently greater than zero at all locations, averaging 171.9 ± 44.7 AU (n=97), representing background noise. Arteries and veins yielded the highest HRF measured flow values, but the relationship between HRF measured flow and perfusate flow was not linear. In arterioles the HRF flow was more linear over a broader range of perfusate flow rates but the peak flow signal was an order of magnitude smaller than that in arteries and veins. Both the linearity and magnitude of the flow signal in venules was less than that in arterioles.