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Rumination consists of voluntary regurgitation of partially digested food, followed by chewing and re-swallowing or expulsion of regurgitated stomach contents (DM-ID2). Little research has systematically analyzed the differential effects of type or quantity of food on rumination across extended observations. This analysis demonstrated that certain (isolated) foods may differentially affect the rate of rumination. Furthermore, patterns of responding and manipulations of quantity may provide evidence for naturally occurring contingencies of punishment for the rumination of particular foods. These results may provide an avenue for minimally invasive, sustainable treatment for individuals with severe and chronic rumination.

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The objective of the present study is to investigate key aspects of ovarian and breast cancers, which are two main causes of mortality among women. Identification of the true behavior of survivorship and influential risk factors is essential in designing treatment protocols, increasing disease awareness and preventing possible causes of disease. There is a commonly held belief that African Americans have a higher risk of cancer mortality. We studied racial disparities of women diagnosed with ovarian cancer on overall and disease-free survival and found out that there is no significant difference in the survival experience among the three races: Whites, African Americans and Other races. Tumor sizes at diagnosis among the races were significantly different, as African American women tend to have larger ovarian tumor sizes at the diagnosis. Prognostic models play a major role in health data research. They can be used to estimate adjusted survival probabilities and absolute and relative risks, and to determine significantly contributing risk factors. A prognostic model will be a valuable tool only if it is developed carefully, evaluating the underlying model assumptions and inadequacies and determining if the most relevant model to address the study objectives is selected. In the present study we developed such statistical models for survival data of ovarian and breast cancers. We found that the histology of ovarian cancer had risk ratios that vary over time. We built two types of parametric models to estimate absolute risks and survival probabilities and to adjust the time dependency of the relative risk of Histology. One parametric model is based on classical probability distributions and the other is a more flexible parametric model that estimates the baseline cumulative hazard function using spline functions. In contrast to women diagnosed with ovarian cancer, women with breast cancer showed significantly different survivorship among races where Whites had a poorer overall survival rate compared to African Americans and Other races. In the breast cancer study, we identified that age and progesterone receptor status have time dependent hazard ratios and age and tumor size display non-linear effects on the hazard. We adjusted those non-proportional hazards and non-linear effects by using an extended Cox regression model in order to generate more meaningful interpretations of the data.

The objective of this study is to address some important questions associated with stomach cancer patients using the data from the Surveillance Epidemiology and End Results (SEER) program of the United States. To better understand the behavior of stomach cancer, we first perform parametric analysis for each patient group (white male, white female, African American male, African American female, other male and female) to identify the probability distribution function which can best characterize the behavior of the malignant stomach tumor sizes. We evaluate the effects of patients’ age, gender and race on the malignant stomach tumor sizes by developing quantile regression models, which gives us a better understanding of the behavior of the malignant stomach tumors. We also proposed statistical models with respect to patients’ malignant stomach tumor size as a function of age for different races and gender group, respectively. The proposed models were evaluated to attest their prediction quality. Furthermore, we have identified the rate of change of the malignant tumor size as a function of age, for gender and race. We evaluated the routine treatment of stomach cancer using parametric and nonparametric survival analysis. We have found that stomach cancer patients who receive surgery with radiation together have a better survival probability than the patients who receive only radiation. We performed decision tree analysis to assist the physician in recommending to his patients the most effective treatment that is a function of their characteristics.

Characterizing hidden solder joint shapes is essential for electronics reliability. Active thermography is a methodology to identify hidden defects inside an object by means of surface abnormal thermal response after applying a heat flux. This research focused on understanding, modeling, and predicting hidden solder joint shapes. An experimental model based on active thermography was used to understand how the solder joint shapes affect the surface thermal response (grand average cooling rate or GACR) of electronic multi cover PCB assemblies. Next, a numerical model simulated the active thermography technique, investigated technique limitations and extended technique applicability to characterize hidden solder joint shapes. Finally, a prediction model determined the optimum active thermography conditions to achieve an adequate hidden solder joint shape characterization. The experimental model determined that solder joint shape plays a higher role for visible than for hidden solder joints in the GACR; however, a MANOVA analysis proved that hidden solder joint shapes are significantly different when describe by the GACR. An artificial neural networks classifier proved that the distances between experimental solder joint shapes GACR must be larger than 0.12 to achieve 85% of accuracy classifying. The numerical model achieved minimum agreements of 95.27% and 86.64%, with the experimental temperatures and GACRs at the center of the PCB assembly top cover, respectively. The parametric analysis proved that solder joint shape discriminability is directly proportional to heat flux, but inversely proportional to covers number and heating time. In addition, the parametric analysis determined that active thermography is limited to five covers to discriminate among hidden solder joint shapes. A prediction model was developed based on the parametric numerical data to determine the appropriate amount of energy to discriminate among solder joint shapes for up to five covers. The degree of agreement between the prediction model and the experimental model was determined to be within a 90.6% for one and two covers. The prediction model is limited to only three solder joints, but these research principles can be applied to generate more realistic prediction models for large scale electronic assemblies like ball grid array assemblies having as much as 600 solder joints.

This thesis addresses the reliability of Goldmann-type applanation tonometers (GAT). It deals with the investigation of the relation between predicted intraocular pressure, IOPG and true pressure, IOPT. The problem of the accuracy of GAT readings has acquired special importance over the last two decades as new types of surgical procedures to correct vision disorders are being explored and gain universal acceptance. The overall aim of the present study is to assess the effects of individual variations in the corneal central thickness (CCT), material properties of the involved tissues and paracentral applanation on the accuracy of IOPG. Two finite element models have been constructed: a two-dimensional axisymmetric model of the cornea and a three-dimensional model of the whole corneoscleral envelope. Various material descriptions were adopted for the cornea in 2D, whereas the 3D model accounted for collagen microstructure and represented a hyperelastic ber reinforced material. Nonlinear analyses were carried out using the commercial general-purpose finite element software ABAQUS. An extensive literature survey and consultations with ophthalmologists and clinicians were the platform for establishing relevant modelling procedures. The results reveal a clear association between all considered parameters and measured IOPG. The effect of assumed CCT is highly dependent on the corneal material properties. Material model alone has a profound effect on predicted IOPG. Variations in tonometer tip application produce clinically signi cant errors to IOPG measurements. Potential effects of corneal stiffness and paracentral applanation on GAT readings are larger than the impact of CCT. The behaviour of the models is broadly in agreement with published observations. The proposed procedures can be a useful tools for suggesting the magnitudes of corrections for corneal biomechanics and possible human errors. The present modelling exercise has an ability to reproduce the behaviour of human cornea and trace it under IOP and GAT, providing potentially useful information on the distribution of stresses and strains. Some recommendations can be drawn in pursuit of the clinical imperatives of ophthalmologists. / QC 20100729

This study consists of developing descriptive, parametric, linear and non-linear statistical models for such natural phenomena as hurricanes, lightning, flooding, red tide and volcanic fallout. In the present study, the focus of research is determining the stochastic nature of phenomena in the environment. These statistical models are necessary to address the variability of nature and the misgivings of the deterministic models, particularly when considering the necessity for man to estimate the occurrence and prepare for the aftermath.The relationship between statistics and physics looking at the correlation between wind speed and pressure versus wind speed and temperature play a significant role in hurricane prediction. Contrary to previous studies, this study indicates that a drop in pressure is a result of the storm and less a cause. It shows that temperature is a key indicator that a storm will form in conjunction with a drop in pressure. This study demonstrates a model that estimates the wind speed within a storm with a high degree of accuracy. With the verified model, we can perform surface response analysis to estimate the conditions under which the wind speed is maximized or minimized. Additional studies introduce a model that estimates the number of lightning strikes dependent on significantly contributing factors such as precipitable water, the temperatures within a column of air and the temperature range. Using extreme value distribution and historical data we can best fit flood stages, and obtain profiling estimate return periods. The natural logarithmic count of Karenia Brevis was used to homogenize the variance and create the base for an index of the magnitude of an outbreak of Red Tide. We have introduced a logistic growth model that addresses the subject behavior as a function of time and characterizes the growth rate of Red Tide. This information can be used to develop strategic plans with respect to the health of citizens and to minimize the economic impact. Studying the bivariate nature of tephra fallout from volcanoes, we analyze the correlation between the northern and eastern directions of a topological map to find the best possible probabilistic characterization of the subject data.

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Este trabalho estuda os resultados obtidos da aplicação de um modelo tridimensional de previsão de comportamento de túneis profundos em rocha reforçados com tirantes passivos. Utiliza-se o método dos elementos finitos e simula-se a escavação pelo sistema de ativação e desativação de elementos. Os tirantes são tratados com uma lei de comportamento elastoplástica e o maciço reforçado com tirantes é considerado um meio homogêneo anisotrópico em escala macroscópica, através do método de homogeneização dos meios periódicos. Para a análise paramétrica foi verificada a influência dos parâmetros do sistema de reforço e do maciço. Resultados em termos de convergência do túnel e tensões são apresentados e indicam que, para o caso analisado, o comprimento dos tirantes é um fator de reduzida influência. A densidade de tirantes possui maior importância, porém, esta não é afetada por modificações na coesão e no módulo de elasticidade do maciço. A distância de aplicação dos tirantes à face de escavação se mostrou significativa somente para valores abaixo de 1/3 do raio do túnel, para valores acima, os deslocamentos já ocorreram e, portanto, não mobilizavam mais os tirantes. Verificou-se que a concentração de tensões σrr acontece na parte superior e inferior do túnel e, também, antes da frente de escavação. O ângulo de atrito demonstrou influência irrisória na convergência, diferentemente da coesão que diminui a convergência, tanto do teto como da parede do túnel, à medida que seu valor aumenta. O empuxo lateral exibiu ainda maior significância, revelando o quanto é importante sua correta determinação, especialmente na convergência lateral do túnel. Ainda, constatou-se a grande importância da combinação de tirantes com revestimento em concreto, que juntos, diminuíram em aproximadamente 25% os deslocamentos no teto do túnel. / This work studies the results obtained from the application of a three-dimensional model to predict the behavior of bolted reinforced rock mass deep tunnel. The finite element method is used to model and simulate the excavation through the activation and deactivation of elements. The bolts are treated with an elastoplastic law and the rock mass is considered as a homogenized anisotropic medium on the macroscopic scale through the homogenization method of periodic media. In the parametric analysis was studied the influence of the parameters of the reinforcement system and the rock mass. Results in terms of convergence of the tunnel and stresses are presented and indicate that, for the studied case, the length of the bolts is a factor of little influence. The density of bolts has a greater importance, however, its influence was not affected by changes in cohesion and elasticity modulus of the rock mass. The distance between the bolted zone and the facing of the tunnel was a significant parameter only for values below 1/3 of the tunnel’s radius, for distances greater than this, the displacements had already occurred and did not mobilize the bolts anymore. It was verified that stress concentration σrr occurs in the top and bottom of the tunnel, and also before the facing of the excavation. The friction angle demonstrated negligible influence on the convergence, unlike the cohesion, which decreases the convergence of the roof and tunnel’s wall as its value increases. The coefficient of lateral earth pressure at rest, k0, exhibited even greater significance, revealing how important its correct determination is, especially for the lateral convergence of the tunnel. Still, it was observed the great importance of the combination of bolts and concrete lining, which together decreased by approximately 25% the displacement of the tunnel’s roof.