Phenotyping with Partially Labeled, Partially Observed Data

Identifying a group of individuals that share a common set of characteristics is a conceptually simple task, which is often difficult in practice. Such phenotyping problems emerge in various settings, including the analysis of clinical data. In this setting, phenotyping is often stymied by persistent data quality issues. These include a lack of reliable labels to indicate the presence of absence of characteristics of interest, and significant missingness in observed variables. This dissertation introduces methods for learning phenotypes when the data contain missing values (partially observed) and labels are scarce (partially labeled). Aim 1 utilizes an unsupervised probabilistic graphical model to learn phenotypes from partially observed data. Aim 2 introduces a related semi-supervised probabilistic graphical model for learning phenotypes from partially labeled clinical data. Finally, Aim 3 describes a method for training deep generative models when the training data contain missing values. The algorithm is then applied in a semi-supervised setting where it accounts for partially labeled data as well

Chronic Stress and Reproductive Function in Female Childhood Cancer Survivors

Reproductive dysfunction is reported as a major concern for childhood cancer survivors (CCS) and is highly correlated with quality of life in this population. Few predictors of post-treatment reproductive function in CCS have been identified. CCS report high levels of psychological stress. Psychological stress activates the hypothalamic-pituitary-adrenal axis, which can disrupt reproductive function. The purpose of this exploratory study was to explore the relationship between perceived stress, biomarkers of hypothalamic-pituitary-adrenal activity, gonadotropin levels, and anti-Müllerian hormone levels in female CCS. This exploratory cross-sectional study included female cancer survivors (ages 16-35) treated for pediatric cancer at the Royal Hospital for Sick Children in Edinburgh, Scotland. Perceived stress was measured using the Perceived Stress Scale (PSS-10). Hypothalamic-pituitary-adrenal activity (HPA) was measured using salivary and hair cortisol levels. Ovarian function was measured using serum gonadotropin levels and serum anti-Müllerian hormone levels. Latent growth curve modeling was used to determine diurnal cortisol slope and intercept. Bayesian structural equation modeling was used to explore the relationship between perceived stress, biomarkers of HPA activity and ovarian function. Twenty-four female (mean age 21.79 ± 5.68) CCS were included in the study. We found an inverse association between perceived stress and ovarian function and a positive association between biomarkers of HPA activity and ovarian function. The findings from this study suggest that perceived stress is negatively associated with ovarian function and that threshold cortisol levels are required for healthy ovarian function in female childhood cancer survivors

Objective physical activity and sleep characteristic measurements using a triaxial accelerometer in eight year olds

Background: Secular trends demonstrate that young children are less active and sleep less. Inequity in an individual\u27s energy balance is known to have poor health outcomes. Academic achievement, academic behavior, and weight status are proxy indicators for health and psychosocial outcomes in this study. Current guidelines in place for sleep and physical activity in childhood are the result of data collected in the form of self-reports. Quantification and qualification of physical activity dimensions and sleep characteristics are essential not only for the purpose of clearly establishing parameters but also for the intent of verifying optimal health outcomes and evaluating interventions related to conditions of energy balance. Purpose: The purpose of this research was to determine the relationships amongst and between the objective dimensions of physical activity, sleep, weight status, academic achievement, and academic behavior. Methods: This cross-sectional correlational descriptive design study monitored the physical activity and sleep duration for 24 hours per day for 7 consecutive days with triaxial accelerometers. Data was successfully gathered on 55 low socioeconomic income African American eight-year-olds. Weight status was measured and body mass index (BMI) was calculated. Standardized scores, subjective grades from the teachers, and attendance records were obtained from the schools. A qualitative component gathered demographic information related to home life, meal habits, and play times. Results: This sample was predominantly overweight/obese. Light intensity activity accounted for 86% of their daytime hours while vigorous activity accounted for less than 1%. Moderate-vigorous activity bouts were inversely significantly correlated with the standardized reading scores. Students with failing reading scores had significantly more time per day in light activity and less time in moderate intensity activity. This sample averaged 8 hours of sleep per night. Students with failing math scores had significantly longer mean wake episodes at night. A significant difference between hours of sleep and weight status was seen. The overweight/obese child slept, on average, less than the normal weight child. Conclusions: Sleep is an important health indicator. Lack of sleep has academic implications. Different weight classifications may benefit from different interventional activities. Future studies should be conducted with larger and diverse samples

Handbook of Life Course Health Development

Health development science; Developmental origins of chronic illnesses; Community; Diabetes; Autism; Obesity; Nutrition; Health disparities across the lifespan; Fetal programmin

A theoretical and practical approach to a persuasive agent model for change behaviour in oral care and hygiene

There is an increased use of the persuasive agent in behaviour change interventions due to the agent‘s features of sociable, reactive, autonomy, and proactive. However, many interventions have been unsuccessful, particularly in the domain of oral care. The psychological reactance has been identified as one of the major reasons for these unsuccessful behaviour change interventions. This study proposes a formal persuasive agent model that leads to psychological reactance reduction in order to achieve an improved behaviour change intervention in oral care and hygiene. Agent-based simulation methodology is adopted for the development of the proposed model. Evaluation of the model was conducted in two phases that include verification and validation. The verification process involves simulation trace and stability analysis. On the other hand, the validation was carried out using user-centred approach by developing an agent-based application based on belief-desire-intention architecture. This study contributes an agent model which is made up of interrelated cognitive and behavioural factors. Furthermore, the simulation traces provide some insights on the interactions among the identified factors in order to comprehend their roles in behaviour change intervention. The simulation result showed that as time increases, the psychological reactance decreases towards zero. Similarly, the model validation result showed that the percentage of respondents‘ who experienced psychological reactance towards behaviour change in oral care and hygiene was reduced from 100 percent to 3 percent. The contribution made in this thesis would enable agent application and behaviour change intervention designers to make scientific reasoning and predictions. Likewise, it provides a guideline for software designers on the development of agent-based applications that may not have psychological reactance