Obsessive-compulsive disorder (OCD) is relatively common (Ruscio, Stein, Chiu, & Kessler, 2010) and leads to significant functional impairment (World Health Organization, 2001). Research suggests that exposure and response prevention (EX/RP) is efficacious for reducing OCD symptoms (NICE, 2006); however, standard outpatient EX/RP does not effectively alleviate symptom severity among a substantial proportion of OCD patients (Abramowitz, 2006). Intensive EX/RP programs have been developed to address the needs of treatment-refractory OCD patients (Veale et al., 2016). While evidence from effectiveness studies suggests that intensive EX/RP programs lead to significant reductions in OCD symptom severity, a portion of patients do not demonstrate improvement in response to intensive treatment (e.g., Björgvinsson, Hart, et al., 2013; Boschen, Drummond, & Pillay, 2008). These findings underscore the need to identify reliable predictors of OCD patient response to intensive EX/RP to help target clinical and research efforts toward improving treatment outcomes for those least likely to respond to current treatment modalities. Therefore, the proposed study evaluated distinct trajectories of OCD symptom change across six-weeks of intensive treatment and examined factors that predict membership in those trajectory groups. Results suggested that three latent subgroups of OCD patients emerged with one demonstrating symptom relapse during intensive treatment. Further, OCD symptom severity was the only baseline factor that predicted latent-class membership. Implications and future directions of research are discussed.

Cognitive dissonance is one of the most frequently cited theories in social psychology (Cooper, 2007) and has been studied in many communication contexts. Although there are many situations in which people need to repeatedly reduce dissonance concerning the same focal belief or behavior, the vast majority of dissonance studies have focused on single instances of dissonance (McGrath, 2017). This dissertation addresses the question of how beliefs and affect change in response to sequentially induced cognitive dissonance. Belief change is frequently studied as a mode of dissonance reduction (Vaidis & Bran, 2018). Information integration theory states that belief change is a function of the scale value (valence) and weight of each piece of information in a message, and that belief change in response to multiple pieces of information is a weighted sum of the valence of the pieces of information (Anderson, 1971; Anderson & Farkas, 1973). Using the sequential information integration model (SIIM; Chung & Fink, 2016; Chung, Fink, Waks, Meffert, & Xie, 2012), this 2 (statement type: justification vs. vote recall) x 2 (evaluation order: evaluation/affect vs. affect/evaluation) within- and between-subjects online experiment tested the effect of sequential induction of dissonance, via repeated exposure to incongruent information, on evaluations of candidates in a hypothetical congressional election. This study, which included 227 participants based in the U.S., replicated key findings from previous studies on belief trajectories, lending further support to the SIIM and illustrating the strength of decision justification as a mechanism for resisting belief change over time. It also found that people respond to negatively valenced messages, compared to positively valenced messages, with greater psychological discomfort and less positive affect even when both types of messages are counterattitudinal. Finally, this research found that people may continue to experience psychological discomfort until finding an effective way to reduce their dissonance. This dissertation replicates, in part, previous SIIM studies and offers insight into the question of how beliefs and affect change in response to sequentially induced cognitive dissonance. / Media & Communication

This dissertation draws on semi-structured interviews with 20 former youth in care to examine their experiences in Ontario’s child welfare system and the long-term impacts of those experiences. Using a symbolic interactionist approach, the study analyzes the biographical disruption that experiences in the care system represented for participants and how this affected their life trajectories. The findings are organized and discussed around three themes: a) participants’ involvement with the system – how they experienced entering, being in, and exiting the system; b) the stigma participants experienced while in care, and their efforts to neutralize or manage the stigma; and c) the impact that their care experiences had on participants as adults. The data reveal a range of challenges that participants encountered while they were in care, including loneliness, isolation, neglect, general mistreatment and in some cases, abuse. Particularly damaging were the stigma and assaults on “self” that participants experienced as a result of their care status. The data also reveal that in one way or another, these early experiences followed participants into their adult lives, leaving them with a myriad of issues and concerns. The dissertation ends with a discussion of the substantive and theoretical contributions of the findings, as well as a section that addresses the policy implications of the research. / Dissertation / Doctor of Philosophy (PhD) / This dissertation draws on semi-structured interviews with 20 former youth in care to examine their experiences in the care system and the long-term impacts of those experiences. Participants described their time in care, including the stereotyping, stigma, abuse, and general mistreatment they encountered, as well as the loneliness and isolation they experienced. Leaving the care system also came with a distinct set of challenges that often persisted into their adult lives. The analysis focuses on impacts relating to identity, self-perception, and material circumstances for those who pass through Ontario’s child welfare system.

Bullying research has grown tremendously throughout the years, and yet, there is a lack of research investigating the biological underpinnings of bullying victimization and perpetration. The single nucleotide polymorphism catechol-O-methyltransferase (COMT) Val158Met is an important candidate gene that has been demonstrated to interact with environmental factors and play an important role in emotion processing. However, it remains unknown whether COMT Val158Met influences youth and adolescents’ involvement as both targets and perpetrators of bullying, considering bully-victims are found to struggle with emotion regulation. To address this knowledge gap, the role of COMT Val158Met on the joint trajectories of bullying victimization and perpetration was investigated in a longitudinal community sample. A latent class growth analysis (LCGA) was used to identify distinct patterns of bullying victimization and perpetration across the ages 10 to 18 years (n = 648). A three-class solution was chosen for bullying victimization where most participants were reflected in a trajectory of low decreasing bullying victimization (74%), followed by moderate stable trajectory of bullying victimization (23%) and a final group following a high stable trajectory of bullying victimization (3%). A two-class solution was chosen for bullying perpetration. As predicted, most participants were reflected in the low stable bullying perpetration group (83%) and a small group followed a moderate increasing/decreasing trajectory of bullying perpetration (16.4%). Dual trajectory models revealed distinct subgroup of individuals involved in bullying either as targets, perpetrators, or bully-victims. Conditional probabilities results suggest that highly victimized youth would in time perpetrate against others while remaining targets of high levels of perpetration (i.e., target to bully-victim), whereas youth moderately victimized were more likely to be uninvolved in bullying perpetration. There was no significant difference in allelic variations (i.e., any Met allele vs Val/Val) of COMT Val158Met between bully-victims and children uninvolved in bullying. Implications of these findings are discussed from a differential susceptibility model. Gaining an understanding of the mechanisms behind the impact of bullying victimization and perpetration on children and adolescent will help provide insight and support for school and clinical prevention and intervention efforts.

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Halphen's Theorem states that, "A necessary and sufficient condition for every dynamical trajectory in a positional field of force in E3 to be planar is that the field of force is either parallel or central." This result has been known for some time, however only the sufficiency part of the theorem is widely documented. A new analytic proof of the necessity part of Halphen's Theorem was developed. The details of this proof motivated the new concepts of a flat point in a field of force and a flat point on a dynamical trajectory in a positional field of force. / Ph. D.

The terminal stage of a minimum-time mission of a high- performance aircraft is studied using both a reduced-order "energy" model formulation and a point-mass model formulation of the aircraft. The mission is confined to vertical plane maneuvers, and is defined as consisting of three stages; a climb to the dash point,a steady-state dash at the high velocity point, and finally, a terminal transient from the dash point to the final state. This terminal maneuver evolves outside of the flight envelope, rapidly decreasing altitude while increasing the velocity to values greater than the dash velocity. The velocity then decreases from this maximum value as required in order to meet the final state specification. Some of the trajectories that are generated during this terminal transient maneuver experience dynamic pressures that will exceed the dynamic pressure limit unless a constraint is placed on the state variables. Because of the need for enforcing this state constraint, a direct adjoining method for handling state constraints in the optimal control problem is studied. A numerical example is given to demonstrate the application of this method of handling state constraints for the case of the dynamic pressure limit. Finally, trajectories are generated that lead from the dash point to a final state having lower altitude and energy values than those of the dash point, and observations are made concerning the characteristics of these maneuvers. / Master of Science