Asthma is a complex, chronic disorder of the airways that is characterized by underlying inflammation, airflow obstruction, and bronchial hyperresponsiveness. Asthma symptoms can be frightening and can have an effect on the emotional functioning Quality of Life (QOL) of school-aged children who have asthma. The purpose of this exploratory, descriptive, cross-sectional, correlational study was to explore the influence of factors identified in the literature on school-aged children’s emotional responses to asthma. Guiding this study was a theoretical model that proposed that the impact of chronic illness severity on QOL is potentially mediated by both resource and barrier factors. The population of interest was 85 school-aged children (ages 6-12) and parents of children who have asthma that were recruited from participants already enrolled in year 4 of the Asthma in Central Texas (ACT) study (R01NR007770, Sharon D. Horner, P.I.) at The University of Texas at Austin. Significant inverse correlations were found between asthma related child emotional functioning QOL and each of the following variables: asthma severity, r = -.30, p < .01; child internalizing behaviors, r = -.26, p < .05, and child externalizing behaviors, r = -.43, p < .001. Significant inverse relationships were found between caregiver emotional functioning QOL and each of the following variables: asthma severity, r = -.39, p < .001; child internalizing behaviors, r = -.22, p < .05 and child externalizing behaviors, r = -.25, p < .05. Multiple regression analysis revealed that asthma severity and child externalizing problems accounted for 26% of the variance in child emotional functioning QOL. No moderators or mediators were identified. Findings from this study imply that externalizing problem behaviors of school-aged children may be a predictor of their negative feelings about their asthma. Nursing educators should consider including the emotional impact of asthma on children in nursing curriculums as this may ultimately influence health care providers to more skillfully address this important issue in both assessment and intervention settings. / text

Although a number of negative consequences of childhood sexual abuse (CSA) have been identified, research has shown that some survivors of CSA are fairly resilient and do not demonstrate these negative outcomes. The current study examined differences between sexually abused and non-abused children on a number of emotional and behavioral dimensions and on achievement. In addition, the role of factors such as intelligence, abuse severity, gender, history of previous psychological interventions and number of foster homes on outcomes in a group of 117 children between the ages of 7 and 16 with sexual abuse histories and 80 controls who did not have a reported history of sexual abuse was examined. Results suggested that children with CSA histories were rated by their caregivers as exhibiting significantly more overall behavior problems than children without CSA histories. CSA history was not found to be significantly associated with self reported depressive symptoms and there was not a significant relationship between gender and caregiver reported behavior problems. However, consistent with expectations, CSA history was significantly associated with intelligence and higher levels of intelligence being predictive of better functioning in a number of areas. Similarly, CSA history was significantly associated with achievement and as expected, higher levels of intelligence were significantly associated with higher overall achievement. Number of foster care placements, abuse severity, history of previous psychological treatment and age at time of testing were generally not found to be significantly associated with resilience.

The simulation as a stand alone optimization tool of a complex system such as a vertical integrated mining operation, significantly over simplifies the actual picture of the system processes involved resulting in an unaccountable effort and resources being spent on optimizing Non Value Added (NA) processes. This study purposed to develop a discrete stochastic simulation-optimization model to accurately capture the dynamics of the system and to provide a structured way to optimize the Value Added (VA) processes. The mine operation model to be simulated for this study is designed as a hybrid level throughput model to identify the VA processes in a mining operation. This study also allows a better understanding of the impact of variation on the likelihood of achieving any given overall result. The proposed discrete stochastic simulation- optimization model provides the ability for a process manager to gain realistic understanding of what a process can do if some factors constraining the process were to be optimized i.e. to conduct what-if analysis. Another benefit of this approached technique is to be able to estimate dependable and reasonable returns on a large optimization related expenditure. The inputs into the model are the capability of the processes which are entered using various variables depending on how much information is available; simple inputs for least amount of information to detailed inputs for well known process to combinational inputs for somewhere in between. The process bottlenecks are identified and measured using the outputs of the model which include production output, severity of constraints, capacity constraints and cumulative bottleneck plots. Once a base case has been identified and documented then the inputs can be modified to represent the business initiatives and the outputs can be compared to the base case to evaluate the true value of the initiative.

Knee osteoarthritis (OA) is a progressive disease and a leading cause of morbidity in older adults, resulting in severe mobility limitations. While the osteoligamentous and neuromuscular systems are altered in knee OA, little data is available to illustrate an association among these systems. The objective of this dissertation was to improve our understanding of how muscle activation patterns during gait are altered across the knee OA severity spectrum and to examine how factors related to the OA process are associated with these alterations. Three independent but related studies were conducted. Muscle activation of the medial and lateral orientations of the gastrocnemii, quadriceps and hamstrings were recorded during gait using surface electromyography for all three studies. Key activation features were identified using principal component analysis. First, participants selected from a large group (n=272) of individuals classified as asymptomatic, ii) moderate ii) severe knee OA were matched for walking velocity. Significant amplitude and temporal activation characteristics were found, supporting that differences among OA severities exist and were not the result of walking velocity only. Secondly, individuals with moderate OA were sub-grouped based on structural severity determined using Kellgren-Lawrence radiographic scores (II-IV) and were compared to a velocity-matched asymptomatic group. Medial gastrocnemius, lateral hamstring and quadriceps amplitudes and temporal patterns were significantly altered by structural severity where significant activation imbalances between the lateral:medial gastrocnemii and hamstrings were found with greater structural impairment (score>II). Thirdly, individuals with moderate OA were prospectively evaluated and divided into knee effusion and no effusion groups, based on a positive bulge test. A significantly higher knee flexion angle during mid-stance, higher quadriceps amplitudes and prolonged hamstrings amplitudes were found when effusion was found. These studies showed that muscle activation patterns during walking were related to i) OA presence and severity based on functional, symptoms and radiographic evidence, ii) structural severity and iii) knee joint effusion. These findings improve our understanding of the interrelationships between alterations in joint structure and function associated with knee OA and muscle activation patterns during gait. These data can contribute to the development of gait-based metrics that can facilitate knee OA diagnosis and monitor progression.

Since the 1980’s horizontal drilling has been a game-changing technology as it allowed the oil and gas industry to produce from reservoirs previously considered marginal or uneconomic. However, while it is considered a mature technology, directional drilling is still done in a reactive fashion. Although many directional drillers are quite adept at predicting the directional response of the bottomhole assembly (BHA) in a given well, the ability to manage all of the drilling parameters on a foot by foot basis while accurately predicting the effects of each parameter is impossible for the human brain alone. Given current rig rates, any amount of increased slide time and its reduced ROP which occurred due to poorly predicted directional response can result in a significant economic impact. There exist many measured parameters or system inputs which have been proven to affect the directional response of a drilling system. One parameter whose effect has not been investigated is mechanical specific energy or MSE. MSE is measure of how efficient the drilling process is in relation to rate of penetration. To date, MSE has primarily been used with for vibration analysis and rate of penetration optimization. The following dissertation covers research into the effect of MSE on the overall wellbore direction change or dog-leg severity. Using published experimental data, a correlation was developed which shows a clear relationship between the dog-leg severity, rate of penetration (ROP) and MSE. The correlation requires only a few hundred feet of drilling before it is able to be tuned to match an individual well’s results. With minimal tuning throughout the drilling of a well, very good results can be obtained with regards to forecasting dog-leg severity as the wellbores were drilled ahead. The correlation was tested using data from multiple, geo-steered wells drilled in a shale reservoir. The analysis of the correlation using real-world data proved it to be a robust and accurate method of predicting the magnitude of dog-leg severity. The use of this correlation results in a smoother wellbore, drilled with a faster overall ROP with a better chance of staying within the geologic targets.

This thesis presents a linearized technique to determine a risk-based index for dynamic security. The method is an extension to an existing technique in which the risk of steady state security is calculated using the mean and variance of load uncertainty. The proposed method is applied to calculate the risk indices for the New England 39 bus test system. The results obtained from the proposed method are validated against those estimated by Monte Carlo simulation. Both approaches produce virtually the same results for small load deviations.

This thesis presents a linearized technique to determine a risk-based index for dynamic security. The method is an extension to an existing technique in which the risk of steady state security is calculated using the mean and variance of load uncertainty. The proposed method is applied to calculate the risk indices for the New England 39 bus test system. The results obtained from the proposed method are validated against those estimated by Monte Carlo simulation. Both approaches produce virtually the same results for small load deviations.

Background: The causes of trends in asthma incidence are not fully understood. Objectives: This study examined trends in age and severity at asthma diagnosis for Ontario children. Methods: Multiple birth cohorts of Ontario children between 1992-2000 were created using health administrative data. Descriptive statistics and multivariable logistic regression examined changes in age and severity of asthma at diagnosis over time. Results: Age at asthma diagnosis decreased (p<0.0001) with a higher relative risk of asthma in children under age three (RR=1.5, 95% CI:1.47, 1.54). Predictors of asthma diagnosis before three included male sex, lower income quintile, and maternal asthma. ‘Severe onset asthma’ increased over time (p<0.0001), its predictors being male sex, lower income quintile, rural residence, comorbidity, low birth weight and age less than three. Conclusions: Observed trends in asthma incidence are not confined to mild disease and are secondary to variations in asthma rates in children under age three.

Background: The causes of trends in asthma incidence are not fully understood. Objectives: This study examined trends in age and severity at asthma diagnosis for Ontario children. Methods: Multiple birth cohorts of Ontario children between 1992-2000 were created using health administrative data. Descriptive statistics and multivariable logistic regression examined changes in age and severity of asthma at diagnosis over time. Results: Age at asthma diagnosis decreased (p<0.0001) with a higher relative risk of asthma in children under age three (RR=1.5, 95% CI:1.47, 1.54). Predictors of asthma diagnosis before three included male sex, lower income quintile, and maternal asthma. ‘Severe onset asthma’ increased over time (p<0.0001), its predictors being male sex, lower income quintile, rural residence, comorbidity, low birth weight and age less than three. Conclusions: Observed trends in asthma incidence are not confined to mild disease and are secondary to variations in asthma rates in children under age three.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 5 uppsatser.