Graduate Theses & Dissertations

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Smote and Performance Measures for Machine Learning Applied to Real-Time Bidding
In the context of Real-Time Bidding (RTB) the machine learning problems of imbalanced classes and model selection are investigated. Synthetic Minority Oversampling Technique (SMOTE) is commonly used to combat imbalanced classes but a shortcoming is identified. Use of a distance threshold is identified as a solution and testing in a live RTB environment shows significant improvement. For model selection, the statistical measure Critical Success Index (CSI) is modified to add emphasis on recall. This new measure (CSI-R) is empirically compared with other measures such as accuracy, lift, efficiency, true skill score, Heidke's skill score and Gilbert's skill score. In all cases CSI-R is shown to provide better application to the RTB industry. Author Keywords: imbalanced classes, machine learning, online advertising, performance measures, real-time bidding, SMOTE
Effect of Listing a Stock on the S&P 500 Index on the Stock’s Volatility
This paper investigates the effect of listing a stock on the S&P 500 Index on the stock’s volatility, using various econometrics models: GARCH and EGARCH. The study mainly addresses three issues; firstly, it analyzes stock volatility in two sub-periods, secondly, it determines whether the announcement can account for the fluctuations in the price of the stock, and finally, it investigates the change in the stock’s variance. After isolating the effects of external and industry shock by using the returns on the S&P 500 Index as a proxy, the author finds evidence of structural change in the volatility of stocks after that stock is added to the index. Additionally, the existence of a dominant symmetric effect, which captures the response of volatility to news, indicate that following the onset of including the stock on the index, information flowing into the market increased. However, the rate at which old news is captured in price falls. The empirical evidence also suggests that on average a stocks variance falls and that the announcement to list a stock on the index has little effect on the stock’s price. Author Keywords: EGARCH, GARCH, S&P 500 Index, Symmetric Effect, Volatility
Comparing Two Tablet-Based Visuomotor Tasks to Standard Laboratory Versions
The assessment of visuomotor function can provide important information about neurological status. Several visuomotor tasks exist for testing in the laboratory, although attempts to make these tests portable to allow quick and reliable assessment have been limited. We developed an assessment tool using two laboratory visuomotor tests as a tablet application: the double-step task, and an interception task. Performance was assessed by measuring the participants’ ability to reach toward unpredictably moving targets in each task. Response patterns were compared across equipment types to determine if participants were responding similarly to the moving targets in the standard laboratory and the tablet version of the tasks. On the double-step task, participants adjusted to the displaced target adequately in both the lab and tablet versions. On the interception task, participants intercepted non-accelerating targets, and performed worse on accelerating targets in both versions of the task. These findings suggest that the tablet version of these tasks assesses similar visuomotor processing as the respective laboratory version. Author Keywords: concussion assessment, double-step task, interception task, visuomotor processing, visuomotor system
Childhood Precursors of Adult Trait Incompleteness
Previous research has suggested that childhood sensory sensitivity may predict adult obsessive compulsive (OC) behaviours. To date, however, research has not addressed how the separate dimensions – harm avoidance and incompleteness - may influence this relationship or why it exists. The current study used a retrospective design to test a) if sensory sensitivity in childhood predicts trait incompleteness in adulthood, as well as b) if emotion regulation variables mediate this relationship. Questionnaires pertaining to OC dimensions and childhood anxieties were completed independently by 172 undergraduate participants and their primary childhood caregiver. Results showed a linear relationship between sensory sensitivity in childhood and incompleteness in adults. Emotion regulation variables failed to mediate this relationship, although a trend for mediation was present. Additionally, exploratory analysis found perfectionism in childhood to be a predictor of trait incompleteness but not harm avoidance, whereas physical anxieties predicted harm avoidance and not incompleteness. Results are discussed in the context of clinical and theoretical implications. Author Keywords: Distress Tolerance, Harm Avoidance, Incompleteness, Obsessive Compulsive Disorder, Sensory Sensitivity, Symmetry
Sexual consent
How one identifies their nonconsensual sexual experiences (NSE) and cognitively integrates the experience into their sexual schemas may affect how individuals perceive and negotiate sexual consent. Previous research has demonstrated that both the method of quantifying NSEs and the labels used to describe NSEs yield different results in psychosexual outcomes associated with NSEs. The current study assessed differences in subjectively and behaviourally quantified NSEs, as well as the role of cognitive and affective appraisals of sexuality and sexual interactions, on sexual consent attitudes. While behaviourally measured NSE history did not significantly influence sexual consent attitudes, the subjective identification of NSEs with various labels did influence attitudes toward sexual consent. Cognitive appraisals of rape and affective appraisals of sexuality also significantly predicted sexual consent attitudes. Implications for future research and NSE prevention are discussed. Keywords: Nonconsensual sexual experiences, sexual consent, quantifying NSEs, affective sexuality, cognitive sexuality Author Keywords: identification, nonconsensual sexual experiences, rape, sexual affectivity, sexual assault, sexual consent
Investigating Ecological Niche Differentiation Among Wild Candids Experiencing Hybridization in Eastern North America
Currently there are large areas of the North American landscape that are occupied by Canis spp. hybrids of several varieties, leading to the logical question as to the genetic structure and ecological function of Canis populations across the continent, and to what extent hybrids reflect contemporary landscapes. This study illustrated patterns of niche differentiation between parental canid species and their hybrids using individual high quality genetic profile and species distribution models to support the intermediate phenotype hypothesis. In general, hybrids demonstrated an intermediate habitat suitability compared to its parental species, across most environmental variables used. A similar trend was observed in the niche metric analysis, where we found that hybrids exhibit intermediate niche breadth, with eastern coyotes and eastern wolves exhibiting the broader and narrower niche, respectively. Our results demonstrate that the intermediate phenotype hypothesis is supported even at a large scale and when involving highly mobile large mammal species. Author Keywords: canid, ecological niche modelling, hybridization, intermediate phenotype, microsatellite genotype, niche differentiation
Tool-use and near-tool effects
After active tool-use visual stimuli near a tool are processed more quickly and accurately than those farther away from a tool. Can these near-tool effects be modulated by training demands? To investigate this we asked the participants to complete a tool training task followed by a cross-modal interference task. During the training task the participants performed quick and accurate pointing movements to reach a strict or moderate criterion. The results indicated that the strict group made faster movements than the moderate group. During the cross-modal interference task visual distractors were presented along handheld tools in conjunction with vibrotactile stimuli on the hand. No significant compatibility effects were found for visual distractors near the hand or tool tip, and no consistent group differences were found. Our findings demonstrate the importance of using a novel tool during training, and that virtual stimuli may not be effective to elicit near-tool effects. Author Keywords: bimodal neurons, cross-modal interference, near-tool effects, tool training, training demands
“Just Say Yes” - Sexual Consent and Boundary Setting On-and Offlinle
The present study examined the understanding and behaviours relating to sexual consent on, and offline among men who have sex with men (MSM) and heterosexual men internationally using a convergent parallel mixed-methods approach. Men of both sexual orientation groups presented challenges with negotiating sexual consent, and this was especially true if they scored higher on aggressive traits or had previously experienced childhood abuse or an unwanted penetrative sexual act in adulthood. However, from the results as a whole, MSM reported struggle more with regards to consent negotiation for a variety of reasons (e.g. sexual scripts, power dynamics, additional sexual settings, sex-role positioning). Limitations and future directions are discussed. Author Keywords: heterosexual men, men who have sex with men, sexual assault, sexual consent, technology
Fathering Experience of the Transition Into Parenthood
Men who become fathers undergo a transitional period during which they adjust to their new role as the caregiver of a child, a time that is usually viewed as a major life transition (Lamb, 2010). Much of the published literature focuses on fathers with identified issues (e.g., divorced fathers); therefore, there is a need for research that looks at the experiences of more typical fathers in the current Canadian context. To understand how fathers experience this transition, a series of focus groups were conducted with first-time fathers across the Peel Region of Ontario, Canada. Analysis of the focus group transcripts using an interpretative phenomenology framework identified four overarching metathemes: intrapersonal experiences, extrapersonal experiences, father’s role, and supports. Practical implications, theoretical implications, and limitations are discussed. Author Keywords: Fathering, Fathering Experience, First-Time Fathers, Transition Into Parenthood
Marital Satisfaction Throughout the Journey of Weight-Loss Surgery
A mixed-methods’ approach was designed to explore the marital impacts following weight-loss surgery (WLS). In Phase 1, ten individual interviews with spouses of five couples were conducted; two of the couples had the wives preparing for WLS, two of the couples consisted of wives who had WLS, and one couple had both received the surgery. Interviews were transcribed and analyzed using a combination of interpretive phenomenological and grounded theory techniques. Findings demonstrated that WLS does have impacts on marriage regardless of where couples are in their journey. All couples discussed food as a possible source of conflict in their relationship. Interviews also reveled that self-esteem is a major factor contributing to their relationship and support is necessary throughout. In Phase 2 an online survey was developed to quantitatively explore the important constructs deemed important from the participants in Phase 1. Relationships between relationship satisfaction, sexual conflict, self-esteem, depression and body image were examined in 54 participants. Results demonstrate that higher levels of support and self-esteem and lower sexual conflict relate to a more satisfactory relationship in individuals post- WLS. Author Keywords: marital satsifaction, mixed-methods, qualitative, relationship satisfaction, weight-loss, Weight-loss surgery
Non-Hippocampal Memory Systems Contributing to Reinstated Context Memory
Damage to the hippocampus (HPC) typically causes retrograde amnesia for contextual fear conditioning. Reinstating the conditioning over several sessions, however, can mitigate the retrograde amnesic effects. Reinstatements, thus, establish a sufficiently strong memory in non-HPC systems to no longer require the HPC for expression, meaning that it has become HPC independent. This thesis aimed to determine the structures comprising the non-HPC system supporting reinstated context fear memory. The contribution of the perirhinal cortex (PRH) and the anterior cingulate cortex (ACC) were examined because of their established role in context memory. Initially, it was demonstrated that HPC damage indeed causes retrograde amnesia for single session, but not reinstated, contextual fear conditioning. Then, it was demonstrated that combined HPC and PRH damage causes retrograde amnesia for reinstated contextual fear conditioning, whereas combined HPC and ACC damage had lesser effects. Therefore, the PRH is a key structure within the non-HPC memory system for reinstated context fear memory. Author Keywords: anterior cingulate cortex, contextual fear conditioning, hippocampus, memory, perirhinal cortex, retrograde amnesia
Cognitive and Affective Theory of Mind in Children and Young Adolescents
Recently, a distinction has been made between cognitive theory of mind, the ability to make inferences about other's beliefs and thoughts, and affective theory of mind, the ability to make inferences about other's emotional states. The purpose of this study is to determine if the distinction between cognitive and affective theory of mind is developmentally appropriate and whether the relation between language and theory of mind is maintained when cognitive and affective theory of mind are examined separately. The sample consisted of 20 children aged 6 to 9 years, and 27 children aged 11 to 15 years. Results showed that the older group outperformed the younger group on both cognitive and affective theory of mind, and that different aspects of language were related to each type of theory of mind. This suggests the distinction between cognitive and affective theory of mind may in fact be valid in this age range. Author Keywords: Affective Theory of Mind, Cognitive Theory of Mind, Development, Language

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Format: 2024/04/13