Stochastic control strategies and adaptive critic methods

Adaptive critic methods have common roots as generalizations of dynamic programming for neural reinforcement learning approaches. Since they approximate the dynamic programming solutions, they are potentially suitable for learning in noisy, nonlinear and nonstationary environments. In this study, a novel probabilistic dual heuristic programming (DHP) based adaptive critic controller is proposed. Distinct to current approaches, the proposed probabilistic (DHP) adaptive critic method takes uncertainties of forward model and inverse controller into consideration. Therefore, it is suitable for deterministic and stochastic control problems characterized by functional uncertainty. Theoretical development of the proposed method is validated by analytically evaluating the correct value of the cost function which satisfies the Bellman equation in a linear quadratic control problem. The target value of the critic network is then calculated and shown to be equal to the analytically derived correct value.

A Stochastic Control Approach to a Parabolic Equation, Reciprocal Processes

2000 Mathematics Subject Classi cation: 49L60, 60J60, 93E20.

A qualitative study of the clinical practice of graduates of a problem-based physical therapy program

The purpose of this study was to examine the perspectives of three graduates of a problem-based leaning (PBL) physical therapy (PT) program about their clinical practice. The study used the qualitative methods of observations, interviews, and journaling to gather the data. Three sessions of audiotaped interviews and two observation sessions were conducted with three exemplars from Nova Southeastern University PBL PT program. Each participant also maintained a reflective journal. The data were analyzed using content analysis. A systematic filing system was used by employing a mechanical means of maintaining and indexing coded data and sorting data into coded classifications of subtopics or themes. All interview transcripts, field notes from observations, and journal accounts were read, and index sheets were appropriately annotated. From the findings of the study, it was noted that, from the participants' perspectives, they were practicing at typically expected levels as clinicians. The attributes that governed the perspectives of the participants about their physical therapy clinical practice included flexibility, reflection, analysis, decision-making, self-reliance, problem-solving, independent thinking, and critical thinking. Further, the findings indicated that the factors that influenced those attributes included the PBL process, parents' value system, self-reliant personality, innate personality traits, and deliberate choice. Finally, the findings indicated that the participants' perspectives, for the most part, appeared to support the espoused efficacy of the PBL educational approach. In conclusion, there is evidence that the physical therapy clinical practice of the participants were positively impacted by the PBL curriculum. Among the many attributes they noted which governed these perspectives, problem-solving, as postulated by Barrows, was one of the most frequently mentioned benefits gained from their PBL PT training. With more schools adopting the PBL approach, this research will hopefully add to the knowledge base regarding the efficacy of embracing a problem-based learning instructional approach in physical therapy programs. ^

When Consumption Embraces Faith: How Religious Beliefs and Practices Influence Consumption

Marketers have long looked for observables that could explain differences in consumer behavior. Initial attempts have centered on demographic factors, such as age, gender, and race. Although such variables are able to provide some useful information for segmentation (Bass, Tigert, and Longdale 1968), more recent studies have shown that variables that tap into consumers’ social classes and personal values have more predictive accuracy and also provide deeper insights into consumer behavior. I argue that one demographic construct, religion, merits further consideration as a factor that has a profound impact on consumer behavior. In this dissertation, I focus on two types of religious guidance that may influence consumer behaviors: religious teachings (being content with one’s belongings), and religious problem-solving styles (reliance on God).

Essay 1 focuses on the well-established endowment effect and introduces a new moderator (religious teachings on contentment) that influences both owner and buyers’ pricing behaviors. Through fifteen experiments, I demonstrate that when people are primed with religion or characterized by stronger religious beliefs, they tend to value their belongings more than people who are not primed with religion or who have weaker religious beliefs. These effects are caused by religious teachings on being content with one’s belongings, which lead to the overvaluation of one’s own possessions.

Essay 2 focuses on self-control behaviors, specifically healthy eating, and introduces a new moderator (God’s role in the decision-making process) that determines the relationship between religiosity and the healthiness of food choices. My findings demonstrate that consumers who indicate that they defer to God in their decision-making make unhealthier food choices as their religiosity increases. The opposite is true for consumers who rely entirely on themselves. Importantly, this relationship is mediated by the consumer’s consideration of future consequences. This essay provides an explanation to the existing mixed findings on the relationship between religiosity and obesity.

Geometric Hamiltonian formulation of a variational problem depending on the covariant acceleration

We consider a second-order variational problem depending on the covariant acceleration, which is related to the notion of Riemannian cubic polynomials. This problem and the corresponding optimal control problem are described in the context of higher order tangent bundles using geometric tools. The main tool, a presymplectic variant of Pontryagin’s maximum principle, allows us to study the dynamics of the control problem.

Problem of Hydroelectric Resources Management: Numerical Approach

In this work we analyze an optimal control problem for a system of two hydroelectric power stations in cascade with reversible turbines. The objective is to optimize the profit of power production while respecting the system’s restrictions. Some of these restrictions translate into state constraints and the cost function is nonconvex. This increases the complexity of the optimal control problem. The problem is solved numerically and two different approaches are adopted. These approaches focus on global optimization techniques (Chen-Burer algorithm) and on a projection estimation refinement method (PERmethod). PERmethod is used as a technique to reduce the dimension of the problem. Results and execution time of the two procedures are compared.

Intellectual disability and sexuality : attitudes of disability support staff and leisure industry employees

Background: The attitudes of support staff and others in the community towards the sexuality of individuals with an intellectual disability (ID) have the potential to influence opportunities for normalised life experiences in the area of sexuality. ----- Method: A sample of 169 disability support staff and 50 employees from leisure and services industries completed the Attitudes to Sexuality Questionnaires (Individuals with an Intellectual Disability [ASQ–ID], and Individuals from the General Population [ASQ–GP]). ----- Results: Support staff and leisure workers reported generally positive attitudes towards the sexuality of individuals with an ID, but men were seen as having less self-control than women. Support staff were more cautious in their views about parenting, and both groups considered a lower level of sexual freedom to be desirable for women with an ID compared to women who are developing typically. Conclusions Attitudes of both groups are generally quite positive in relation to ID and sexuality.

Examination of social demographic status, disease status, health behaviours and quality of life in older Australians using the theory of planned behaviour model

The increase of life expectancy worldwide during the last three decades has increased age-related disability leading to the risk of loss of quality of life. How to improve quality of life including physical health and mental health for older people and optimize their life potential has become an important health issue. This study used the Theory of Planned Behaviour Model to examine factors influencing health behaviours, and the relationship with quality of life. A cross-sectional mailed survey of 1300 Australians over 50 years was conducted at the beginning of 2009, with 730 completed questionnaires returned (response rate 63%). Preliminary analysis reveals that physiological changes of old age, especially increasing waist circumference and co morbidity was closely related to health status, especially worse physical health summary score. Physical activity was the least adherent behaviour among the respondents compared to eating healthy food and taking medication regularly as prescribed. Increasing number of older people living alone with co morbidity of disease may be the barriers that influence their attitude and self control toward physical activity. A multidisciplinary and integrated approach including hospital and non hospital care is required to provide appropriate services and facilities toward older people.

Do people gamble with their lives : The relationship between risky driving behaviour and other risky behaviours

General risky behaviour is explored for correlation with risky driving behaviour in light of two theories, self-control and cross-situational consistency. Identification of general risky behaviours associated with risky driving behaviour, and the theory that best predicts the behaviours, will enable better targeting of intervention and education strategies to reduce driving related fatalities and injuries. A correlational study using participants (N=152) drawn from first year university undergraduates and the public surveyed their lifestyle and behaviours. Relationships were found between risky driving behaviours and other risky behaviours such as alcohol consumption, cannabis use and performing unlawful activities. No significant differences were found between genders, with the exception that males were more likely to believe that they were at risk of injury from their employment, χ2 (1, N = 152) = 4.49, p = .03, were more likely to have performed an unlawful offence, χ2 (1, N = 152) = 11.77, p = .001 and were more likely to drink drive, t (55.41) = -3.87, p < .001, mean difference = -0.63, CI 95% (-0.9, -0.37). People engaged in risky driving behaviours were more likely to engage in other risky behaviours. The theories that were explored were unable to accurately predict an association between general risky behaviour and driving without a license or when disqualified. Cross-situational consistency explained 20% (R2adj = .16) of the variance in which people engaged in risky driving with low self-control theory explaining an additional 0.3% variance (R2change = .003), F (8,143) = 6.92, p < .001. Driving while under the influence of alcohol could be predicted by risky behaviours in lifestyle, health, smoking, cannabis use and alcohol consumption, F (8,143) = 6.92, p < .001. The addition of self-control was not significant.

A model of workplace safety incorporating worker interactions and simple interventions

Although there was substantial research into the occupational health and safety sector over the past forty years, this generally focused on statistical analyses of data related to costs and/or fatalities and injuries. There is a lack of mathematical modelling of the interactions between workers and the resulting safety dynamics of the workplace. There is also little work investigating the potential impact of different safety intervention programs prior to their implementation. In this article, we present a fundamental, differential equation-based model of workplace safety that treats worker safety habits similarly to an infectious disease in an epidemic model. Analytical results for the model, derived via phase plane and stability analysis, are discussed. The model is coupled with a model of a generic safety strategy aimed at minimising unsafe work habits, to produce an optimal control problem. The optimal control model is solved using the forward-backward sweep numerical scheme implemented in Matlab.

Audit fees and asset securitization risks

The thesis investigates “where were the auditors in asset securitizations”, a criticism of the audit profession before and after the onset of the global financial crisis (GFC). Asset securitizations increase audit complexity and audit risks, which are expected to increase audit fees. Using US bank holding company data from 2003 to 2009, this study examines the association between asset securitization risks and audit fees, and its changes during the global financial crisis. The main test is based on an ordinary least squares (OLS) model, which is adapted from the Fields et al. (2004) bank audit fee model. I employ a principal components analysis to address high correlations among asset securitization risks. Individual securitization risks are also separately tested. A suite of sensitivity tests indicate the results are robust. These include model alterations, sample variations, further controls in the tests, and correcting for the securitizer self-selection problem. A partial least squares (PLS) path modelling methodology is introduced as a separate test, which allows for high intercorrelations, self-selection correction, and sequential order hypotheses in one simultaneous model. The PLS results are consistent with the main results. The study finds significant and positive associations between securitization risks and audit fees. After the commencement of the global financial crisis in 2007, there was an increased focus on the role of audits on asset securitization risks resulting from bank failures; therefore I expect that auditors would become more sensitive to bank asset securitization risks after the commencement of the crisis. I find that auditors appear to focus on different aspects of asset securitization risks during the crisis and that auditors appear to charge a GFC premium for banks. Overall, the results support the view that auditors consider asset securitization risks and market changes, and adjust their audit effort and risk considerations accordingly.

Choice impulsivity: Definitions, measurement issues, and clinical implications

Background Impulsivity critically relates to many psychiatric disorders. Given the multifaceted construct that impulsivity represents, defining core aspects of impulsivity is vital for the assessment and understanding of clinical conditions. Choice impulsivity (CI), involving the preferential selection of smaller sooner rewards over larger later rewards, represents one important type of impulsivity. Method The International Society for Research on Impulsivity (InSRI) convened to discuss the definition and assessment of CI and provide recommendations regarding measurement across species. Results Commonly used preclinical and clinical CI behavioral tasks are described, and considerations for each task are provided to guide CI task selection. Differences in assessment of CI (self-report, behavioral) and calculating CI indices (e.g., area-under-the-curve, indifference point, steepness of discounting curve) are discussed along with properties of specific behavioral tasks used in preclinical and clinical settings. Conclusions The InSRI group recommends inclusion of measures of CI in human studies examining impulsivity. Animal studies examining impulsivity should also include assessments of CI and these measures should be harmonized in accordance with human studies of the disorders being modeled in the preclinical investigations. The choice of specific CI measures to be included should be based on the goals of the study and existing preclinical and clinical literature using established CI measures.

Characterising resistance to overconsumption : a biopsychological analysis

This thesis investigated biopsychological factors involved in successfully resisting overconsumption in an environment promoting obesity, and differences between individuals who were and were not able to resist overconsumption. Results showed that self control was a key factor in successful resistance, whereas sensitivity to food reward was associated with overconsumption susceptibility. Reduced self control may be a consequence as well as a cause of obesity, and may not recover following weight loss. Self control was not enhanced through an exercise programme that aimed to ameliorate brain fitness through improved cardiovascular fitness.

The implicit structure of positive characteristics

The implicit structure of positive character traits was examined in two studies of 190 and 100 undergraduates. Participants judged the pairwise covariation or semantic similarity of 42 positive characteristics using a sorting or a rating task. Characteristics were drawn from a new classification of strengths and virtues, the Five-Factor Model, and a taxonomy of values. Participants showed consistent patterns of perceived association among the characteristics across the study conditions. Multidimensional scaling yielded three consistent dimensions underlying these judgments (“warmth vs. self-control,” “vivacity vs. decency,” and “wisdom vs. power”). Cluster analyses yielded six consistent groupings—“self-control,” “love,” “wisdom,” “drive,” “vivacity,” and “collaboration”—that corresponded only moderately to the virtue classification. All three taxonomies were systematically related to this implicit structure, but none captured it satisfactorily on its own. Revisions to positive psychology’s classification of strengths are proposed.

Psychological predictors of opportunistic snacking in the absence of hunger

Increased frequency of eating in the absence of homeostatic need, notably through snacking, is an important contributor to overconsumption and may be facilitated by increased availability of palatable food in the obesogenic environment. Opportunistic initiation of snacking is likely to be subject to individual differences, although these are infrequently studied in laboratory-based research paradigms. This study examined psychological factors associated with opportunistic initiation of snacking, and predictors of intake in the absence of homeostatic need. Fifty adults (mean age 34.5 years, mean BMI 23.9 kg/m2, 56% female) participated in a snack taste test in which they ate a chocolate snack to satiation, after which they were offered an unanticipated opportunity to initiate a second eating episode. Trait and behavioural measures of self control, sensitivity to reward, dietary restraint and disinhibited eating were taken. Results showed that, contrary to expectations, those who initiated snacking were better at inhibitory control compared with those who did not initiate. However, amongst participants who initiated snacking, intake (kcal) was predicted by higher food reward sensitivity, impulsivity and BMI. These findings suggest that snacking initiation in the absence of hunger is an important contributor to overconsumption. Consideration of the individual differences promoting initiation of eating may aid in reducing elevated eating frequency in at-risk individuals.