The pattern of mucosal blood flow in normal human stomachs, and benign gastric ulcers was assesed with laser Doppler flowmetry and the relationship between a single determination of ulcer blood flow and the systemic level of growth factors was investigated. A significant ascending gradient in mucosal blood flow from the antrum to fundus was demonstrated. Different levels of cellular activity in the regions of the stomach may explain this gradient. In the gastric ulcers that healed on standard medical therapy mucosal blood flow was significantly increased in comparison to normal stomachs. In the ulcers that were refractory to standard medical therapy mucosal blood flow was significantly lower than in normal stomachs and healing ulcers. Higher systemic levels of the growth factor bFGF were demonstrated in healing ulcers compared to non-healing ulcers. Gastric mucosal blood flow can increase in response to the increased metabolic demands of healing, however impairment of this response may be an important factor preventing healing of benign gastric ulcers. It would appear that non-healing of gastric ulcers can be predicted at initial diagnosis by reduced peri-ulcer gastric mucosal blood flow and low blood levels of bFGF. / Thesis (M.Med.Sc.)-University of Natal, Durban, 1999.

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No description available.

Orientador: Anibal Faundes / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-08T03:02:55Z (GMT). No. of bitstreams: 1 FerreiraNeto_PedroPires_D.pdf: 756822 bytes, checksum: 391b94a37ae61d1eb12c2c4f4b8aeacb (MD5) Previous issue date: 2006 / Resumo: Objetivo: Avaliar a capacidade dos índices de pulsatilidade das artérias umbilical e cerebral média e a relação do índice de pulsatilidade umbilico-cerebral em fetos de gestantes hipertensas de predizer risco de resultados perinatais adversos de acordo com a idade gestacional. Métodos: No período de janeiro de 2000 a agosto de 2004 foi realizada a avaliação dopplervelocimétrica dos índices de pulsatilidade da artéria umbilical (IPAU), da artéria cerebral média (IPACM) e da relação do índice de pulsatilidade umbilical/cerebral (IPAU/IPACM) de 289 gestantes com hipertensão artérial, com idade gestacional entre 24 a 41 semanas de gestação. Os resultados doplervelocimétricos que apresentaram IPAU acima do percentil 95 ou fluxo diastólico ausente ou reverso, IPACM abaixo do percentil 5 e relação IPAU/IPACM acima do percentil 95, foram avaliados quanto à capacidade de prever resultados perinatais adversos (Apgar do 5º minuto < 7, recém-nascido pequeno para a idade gestacional (RN PIG), ocorrência da doença da síndrome do desconforto respiratório (SDR), ocorrência da síndrome hipóxico-isquêmica (SHI) e óbito perinatal. Estes resultados foram comparados entre si sem ajuste e com ajuste pela idade gestacional no parto. Resultados: Os resultados alterados da dopplervelocimetria não estiveram associados ao risco de Apgar do 5º minuto < 7, antes de ajustar por idade gestacional. Com o ajuste, o risco aumentou. Entretanto, apenas a associação com alteração do IPAU alcançou significação estatística. O risco de ocorrência de recém-nascido PIG aumentou entre cinco e sete vezes na análise sem ajuste e em torno de três vezes na análise ajustada, e foi estatisticamente significativa para todos os parâmetros da dopplervelocimetria estudados. O risco de SHI aumentou entre duas e cinco vezes antes do ajuste. O aumento do risco ajustado foi significativo apenas para IPAU e relação IPAU/IPACM. Quanto ao risco da SDR houve aumento de duas a seis vezes na análise sem ajuste, mas na análise ajustada não houve aumento. Na análise da mortalidade perinatal o risco não ajustado foi entre três e dez vezes maior, nos casos com alteração do IPAU, IPACM e na relação IPAU/IPACM. Na análise ajustada apenas o IPAU alterado apresentou associação com risco quase três vezes maior e foi estatisticamente significativo. Conclusão: Neste grupo selecionado de gestantes hipertensas, a análise isolada do IPAU apresentou melhor correlação com os resultados perinatais do que a análise do IPACM ou da relação IPAU/IPACM, particularmente quando a análise foi feita com o ajuste da idade gestacional / Abstract: Objetive: To evaluate the capacity of the pulsatility Index of the umbilical artery and of the median cerebral artery and of the umbilical/cerebral ratio to predict adverse perinatla outcomes. Métodos: Dopplervelocimetric evaluation of the pulsatility Index of the umbilical artery (IPAU) and of the Median cerebral artery (IPACM) and of the umbilical/cerebral ratio (IPAU/IPACM) was carried out 289 pregnant women with hypertension at 24 through 41 weeks of gestation. Abscent or reverse diastolic flux and, IPAU above the 95 percentil, IPACM below percentil 10 and IPAU/IPACM ratio over the 95 percentil were evaluated in relation to its associasaion with adverse perinatal outcomes (5 minutes Apgar score < 7, small for gestational age (PIG), hialine membrane disease (DMH), hipoxic ischemic syndrome (SHI) and perinatal death. These results were compare before and after adjustment by gestational age at birth. Results: Abnormal Doppler results were not associated with the risk of 5 minutes Apgar score < 7 before adjustment by gestational age. After adjustment the risk increased, but only adnormal IPAU was significantly associated with. 5 minutes Apgar score < 7. The risk of PIG was 5 to 7 times higher before adjustment and arround 3 times and significantly higher after adjustment in cases with alterations in any of the three Doppler indicators studied. The risk of SHI was increased between 2 and 5 times before adjustment, but after adjustment the risk was significantly higher when the IPAU and the IPAU/IPACM ratio were adnormal. The risk DMH appeared to be between 2 and 6 times higher before adjustment, but became insignificant for the three indicators after adjustment. The risk of perinatal death before adjustment was between 3 and 10 times higher in cases with alteration in the IPAU, IPACM and the IPAU/IPACM ratio. After adjustment, only adnormal IPAU was associated with a three folds increase risk, that was statistiocally significant. Conclusion: In this selected group of preganat women with hypertension the isolated analysys of IPAU showed the best correlation with adverse perinatal outcomes, particularly after adjustment by gestational age / Doutorado / Tocoginecologia / Doutor em Tocoginecologia

A set of laboratory experiments was carried out to distinguish flow characteristics(bed origin, shear velocity, turbulence intensity, turbulent kinetic energy) between beds of differing gravel angularity. Ten vertical profiles of velocity measurements were taken from angular and rounded fixed gravel beds with a 16 MHz micro acoustic Doppler velocimeter (ADV) sampling at 50 Hz. Both gravel beds had a bottom slope of 0.2% and were in the intermediate - roughness scale. Shear velocities were calculated using three common methods: St Venant, Reynolds stress, and Clauser. The Reynolds stress method resulted in the closest visual match to turbulence distributions proposed by others. The bed origin was found to be on average 0.24D50 and 0.21D50 for the angular and rounded gravel beds respectively. These differences, however, were not statistically significant. Turbulence intensity within 20% of the bed showed considerable scatter. The difficult measuring conditions likely prevented the ADV to detect significant differences of turbulence intensity in the longitudinal and transverse directions between the two gravel beds. But the ADV measurements in the vertical direction may well resolve turbulence even in difficult flow conditions (determined by acoustic Doppler performance curve formulation). For the vertical direction, the angular gravel bed showed an increase in TImax that extended throughout the profile. The increased turbulence intensity had a concomitant effect of increasing the turbulent kinetic energy for the angular bed.

Thesis. 1975. Ph.D.--Massachusetts Institute of Technology. Dept. of Nuclear Engineering. / Vita. / Includes bibliographical references. / Ph.D.

No description available.

A technique to determine the three-dimensional velocity of a point on a vibrating structure is developed. This technique uses a reference-beam type laser-doppler velocimeter in three independent positions to determine the target velocity in a non orthogonal coordinate system. The transformation from non-orthogonal to orthogonal coordinate systems is analyzed. The sensitivities of the resulting velocity to measurement noise and position errors are also analyzed. Recommendations are made for future testing and applications of this technique. / Master of Science

Turbulent swirling flows are important in many applications including gas turbines, furnaces and cyclone dust separators among others. Although the mean flow fields have been relatively well studied, a complete understanding of the flow field including its dynamics has not been achieved. The work contained in this dissertation attempts to shed further light on the behavior of turbulent swirling flows, especially focused on the dynamic behavior of a turbulent swirling flow encountering a sudden expansion. Experiments were performed in a new isothermal turbulent swirling flow test facility. Two geometrical nozzle configurations were studied. The \cb\ nozzle configuration exhibits a cylindrical \cb\ in the center of the nozzle. The free vortex nozzle configuration is obtained when the cylindrical \cb\ is removed. Detailed laser velocimeter measurements were performed to map out the flow field near the sudden expansion of the 2.9" (ID) nozzle leading to the 7.4" (ID) downstream section. In addition to presenting detailed flow profiles for both nozzle and downstream flow fields, representative frequency spectra of the flow dynamics are presented. Along with the flow time histories and histograms, the wide variety of dynamic behavior was thus described in great detail. The dynamics observed in the experiment can be classified into three main categories: coherent and large scale motion, intermittent motion and coherent periodic motion. Free vortex geometry flows, in the parameter space of the experiments (Swirl number = 0 - 0.21), exhibited mostly coherent and large scale motion. The spectra in these cases were broadband with very light concentration of spectral energy observed in some specific cases. Center--body geometry flows exhibited all three categories of flows as swirl strength was increased from zero. Flows with little or no swirl exhibited broad--band spectra similar to those for the free vortex geometry. Intermediate swirl levels resulted in a large amount of low frequency energy which, with the aid of the time histories, was identified as a large scale intermittence associated with radial movement of the annular jet as it enters the sudden expansion. Large swirl levels resulted in high magnitude coherent oscillations concentrated largely just downstream of the sudden expansion. Linear stability analysis was used to help in the interpretation of the observed dynamics. Although, as implemented here (using the parallel flow assumption), the analysis was not successful in quantitatively matching the experimentally observed dynamics, significant insight into the physical mechanisms of the observed dynamics was obtained from the analysis. Specifically, the coherent oscillations observed for larger swirl levels were able to be described in terms of the interaction between the inner and outer shear layers of the flow field. / Ph. D.

The structure and behavior of the bimodal flow of the horseshoe vortex at the nose of a wing-body junction flow was studied. The wing consists of a 3:2 elliptic nose and a NACA 0020 tail joined at the maximum thickness (t). Measurements were performed with an approach flow conditions of U_ref = 27.5 m/s, Re_θ = 6700 at x/t=-2.15, and δ/t=0.5. A rapidly-scanning two-velocity-component laser-Doppler anemometer system was developed for use in investigating this flow. U and V velocity components were measured simultaneously with surface pressure measurements at the location of the most bimodal pressure histogram (x/t=-0.26). Mean (U, V) and rms (u’, v’) velocity components were obtained at four x locations, x/t= -0.15, -0.20, -0.25, -0.30, and show the same flow features measured in previous studies at this facility. Cross-correlations between the velocity and the surface pressure fluctuations were obtained. Large correlations were found between the u fluctuations (x/t= -0.15, -0.25, and -0.30) near the wall, y/t < 0.05, and the surface pressure fluctuations. The z fluctuations for y/t > 0.1 at all four x-locations lead the surface pressure fluctuations. Space-time correlations between the velocity fluctuations near the wall with the velocity fluctuations along the scan were also obtained. The correlations at x/t=-0.25 and x/t=-0.30 show that the fluctuations in the outer region, y/t > 0.1, are significantly correlated with and lead the velocity fluctuations near the wall. These measurements support a model of a single primary junction vortex that changes size and location in front of the wing. The strength or circulation of this vortex varies by only 20%. Event-threshold conditional-averages of velocity were obtained based on the surface pressure signal, which is sensitive to the movement of the junction vortex. These show that the junction vortex is concentrated near the nose, with large backflow, when the surface pressure signal is above the mean. The junction vortex is larger, with smaller backflow near the nose, when the surface pressure signal is below the mean. The velocity-pressure cross-correlations and space-time correlations indicate that the behavior of the junction vortex is influenced by fluctuations originating upstream and propagating inward and downward toward the wing. / Ph. D.