Theses, Dissertations, and other Required Graduate Degree Essays

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This collection contains digitized SFU theses except for those theses submitted within the last 12 months. If you cannot find the thesis you are looking for please search Recently Submitted Theses as it may be a recently submitted thesis and thus not yet available in Summit.

Understanding jump dynamics using liquidity measures

Author: 
Date created: 
2020-07-15
Abstract: 

Numerous past studies investigate the relationship between volatility and other relevant variables, e.g., asset jumps, liquidity factors. However, empirical studies examining the link between liquidity and jumps are almost non-existent. In this report, we investigate the possible improvement in estimating so-called jump distribution parameters computed from intraday returns by including liquidity measures. More specifically, we first calculate the jump distribution parameters by using classic jump detection techniques in the spirit of Lee and Mykland (2008) and Tauchen and Zhou (2011), and we then use them as our responses in the heterogeneous autoregressive model \citep[e.g.,][]{corsi2009simple}. We examine the in-sample performance of our model and find out that liquidity measures do provide extra information in the estimation of the jump intensity and jump size variation. We also apply the same technique but using one-period-ahead instead of contemporaneous responses; we again find extra explanatory power when the liquidity measures are included.

Document type: 
Graduating extended essay / Research project
File(s): 
Supervisor(s): 
Jean-François Bégin
Department: 
Science: Department of Statistics and Actuarial Science
Thesis type: 
(Project) M.Sc.

Adolescent intimate partner violence: The case for outcome-specific and developmentally informed guidelines to evaluate and manage risk

Date created: 
2020-07-23
Abstract: 

Intimate partner violence (IPV) among adolescents, which can be defined as any actual, attempted, or threatened physical or sexual harm between intimate partners aged 12 to 17, is an ongoing, serious, and global problem. Although structured decision-making tools have been developed to evaluate an adolescent’s risk to engage in general violence and offending, it is unclear whether these tools can be used to evaluate risk to perpetrate IPV. In addition, although tools have been developed to evaluate IPV risk among adults, these tools were not intended for use with adolescents and thus may be inappropriate. In this dissertation, the utility of four widely used risk assessment tools for evaluating adolescent IPV risk was examined. First, the predictive validity of the Structured Assessment of Violence Risk in Youth (SAVRY), Youth Level of Service/Case Management Inventory (YLS/CMI), and Psychopathy Checklist: Youth Version (PCL:YV) were examined for IPV perpetration and any violent and any reoffending in a sample of 156 young offenders on probation in Western Canada. Results indicated that total scores and summary risk ratings on the SAVRY and YLS/CMI and total scores on the PCL:YV were significantly predictive of any violent and any reoffending with moderate to large effect sizes over a 2-year follow-up period but were modestly and non-significantly associated with the perpetration of IPV. Second, a systematic review was conducted to evaluate the applicability of items on an adult IPV tool, the Spousal Assault Risk Assessment Guide - Version 3 (SARA-V3), to adolescents. A total of 71 articles (N = 45,202 adolescents) that address risk and/or protective factors associated with adolescent IPV perpetration or victimization were examined. Most SARA-V3 items were found to have empirical support among adolescents. However, results also indicate that several factors should be added, removed, or altered to better reflect developmental considerations among this age group. These findings suggest that the field would benefit from the development of a specialized adolescent IPV risk assessment and management tool. This dissertation concludes with a discussion of the steps being taken to adapt the SARA-V3 for use with adolescents and implications for research, policy, and practice.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Kevin Douglas
Department: 
Arts & Social Sciences: Department of Psychology
Thesis type: 
(Thesis) Ph.D.

Supervised basis functions applied to functional regression and classification

Author: 
Date created: 
2020-07-29
Abstract: 

In fitting functional linear models, including scalar-on-function regression (SoFR) and function-on-function regression (FoFR), the intrinsically infinite dimension of the problem often demands an limitation to a subspace spanned by a finite number of basis functions. In this sense, the choice and construction of basis functions matters. We discuss herein certain supervised choices of basis functions for regression/classification with densely/sparsely observed curves, and give both numerical and theoretical perspectives. For SoFR, the functional principal component (FPC) regression may fail to provide good estimation or prediction if the response is highly correlated with some excluded FPCs. This is not rare since the construction of FPCs never involves the response. We hence develop regression on functional continuum (FC) basis functions whose framework includes, as special cases, both FPCs and functional partial least squares (FPLS) basis functions. Aiming at the binary classification of functional data, we then propose the continuum centroid classifier (CCC) built upon projections of functional data onto the direction parallel to FC regression coefficient. One of the two subtypes of CCC (asymptotically) enjoys no misclassification. Implementation of FPLS traditionally demands that each predictor curve be recorded as densely as possible over the entire time span. This prerequisite is sometimes violated by, e.g., longitudinal studies and missing data problems. We accommodate FPLS for SoFR to scenarios where curves are sparsely observed. We establish the consistency of proposed estimators and give confidence intervals for responses. FPLS is widely used to fit FoFR. Its implementation is far from unique but typically involves iterative eigen decomposition. We introduce an new route for FoFR based upon Krylov subspaces. The method can be expressed in two equivalent forms: one of them is non-iterative with explicit forms of estimators and predictions, facilitating the theoretical derivation; the other one stabilizes numerical outputs. Our route turns out to be less time-consuming than other methods with competitive accuracy.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Richard A. Lockhart
Department: 
Science: Department of Statistics and Actuarial Science
Thesis type: 
(Thesis) Ph.D.

Mechanisms that relate transverse loading of muscle to changes in contractile performance

Author: 
Date created: 
2020-07-09
Abstract: 

Research has shown that factors such as the contraction of surrounding muscle, resistance to radial expansion, and external transverse loading have an effect on the way that muscle performs. Such factors are often ignored when doing muscle experiments, yet they can have significant effects on the force and power that a muscle is able to produce. The aim of this thesis is to determine to what degree external loading affects muscle force and to study the changes in muscle architecture due to external loading. The purpose of this thesis was to determine whether external transverse loading causes force reduction in humans, how external transverse loading affects muscle architecture, and describe the mechanisms involved. We applied an external transverse load to the medial gastrocnemius of prone participants as a point loaded mass. Transverse loading reduced ankle torque with higher loads resulting in greater reductions. Passive transverse loading caused a decrease in the resting pennation angle and muscle thickness, with higher loads leading to greater decreases. During activation of the muscle the pennation angle, muscle thickness, and fascicle thickness increase transiently relative to the amount of transverse loading. Alterations to the design of the experiment were made by applying a multi-directional external transverse load and changing the position of the participants from prone to seated, where sitting changed the resting length of the muscle. Our altered experiments showed no change in ankle torque. Minor differences were shown for pennation angle and muscle thickness both at passive resting values and peak active values, but not for fascicle thickness and fascicle. Fascicle thickness decrease transiently, and fascicle length increased. We replicated the external transverse loading experiments using a three-dimensional finite element model of a fibre-reinforced, non-linearly-elastic transversely isotropic composite biomaterial. The model consists of active and passive force-length properties of muscle fibre as well as passive force-length properties of base material. Results show external transverse loading causes architecture changes and reductions in muscle force. Muscle force reduction is dependent on direction of loading, initial pennation, and initial muscle length.

Document type: 
Thesis
File(s): 
Supervisor(s): 
James M. Wakeling
Department: 
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Thesis) Ph.D.

Mathematics teacher tension: Arising in, and through, their attempt to change practice

Author: 
Date created: 
2020-07-07
Abstract: 

While much research is devoted to what it is teachers do, there is far less known about why teachers do the things they do. This is particularly true in the area of mathematics teacher change where, despite an abundance of literature on ways to think about and facilitate change in mathematics teaching practice, a lack of meaningful change in practice is an ongoing concern. This dissertation explores this gap through a qualitative analysis of tension experienced by fourteen teachers engaged in implementing change in their mathematics practice. Viewing teachers as tension managers whose actions are shaped by an undercurrent of uncertainty, offers insight into the ‘why’ behind their actions; it allows for a focus on the process of change in practice, rather than the product. The study uses theoretical constructs of teacher change and teacher agency to position teachers as arbiters of change, responsible for their own growth. Using a hermeneutic phenomenology approach, data collection was conducted in three distinct phases and comprised interviews with, written reflections by, and classroom observations of, groups of teachers at various stages of change. Using a form of emergent coding, data was first analysed for contexts which held potential for change. These were then re-examined for tension using emotion and hedging as indicators of uncertainty. The results indicate that teachers experience internal and external tension that can both trigger and impede meaningful change in mathematics teaching practice. This is dependent not only on the context, but also on the quality of tension, as two types (useful tension and productive tension) are identified and explored for their potential to impact change. Furthermore, the data supports the view that managing tension in change is an agential response. Two management strategies are articulated: living with tension and resolving tension. Finally, the presence of unacknowledged virtual tension was hypothesized as an impediment to the achievement of meaningful change.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Peter Liljedahl
Department: 
Education: Faculty of Education
Thesis type: 
(Thesis) Ph.D.

Understanding and estimating predictive performance of statistical learning methods based on data properties

Author: 
Date created: 
2020-07-14
Abstract: 

Many Statistical Learning (SL) regression methods have been developed over roughly the last two decades, but no one model has been found to be the best across all sets of data. It would be useful if guidance were available to help identify when each different method might be expected to provide more accurate or precise predictions than competitors. We speculate that certain measurable features of a data set might influence methods' potential ability to provide relatively accurate predictions. This thesis explores the potential to use measurable characteristics of a data set to estimate the prediction performance of different SL regression methods. We demonstrate this process on an existing set of 42 benchmark data sets. We measure a variety of properties on each data set that might be useful for differentiating between likely good- or poor-performing regression methods. Using cross-validation, we measure the actual relative prediction performance of 12 well-known regression methods, including both classical linear techniques and more modern flexible approaches. Finally, we combine the performance measures and the data set properties into a multivariate regression model to identify which properties appear to be most important and to estimate the expected prediction performance of each method.

Document type: 
Graduating extended essay / Research project
File(s): 
Supervisor(s): 
Thomas Loughin
Department: 
Science: Department of Statistics and Actuarial Science
Thesis type: 
(Project) M.Sc.

Using anthropometrics and dental formation stages of contemporary children to investigate the impact of biological mortality bias on interpretations of past population health

Author: 
Date created: 
2020-05-22
Abstract: 

Biological mortality bias is the concept that within a population, the individuals who die (non-survivors) are biologically different from their surviving peers. Because non-survivors may have experienced more health insults during their lives than survivors, they may differ from survivors in their biological phenotypes. Thus, if biological mortality bias exists and is substantial in magnitude, interpretations of past population health made from skeletal samples (non-survivors) may not accurately reflect the health of the surviving population. This dissertation explores biological mortality bias as reflected in the growth of juvenile individuals aged birth to 12 years. Growth is known to be susceptible to environmental influences, and thus has been widely used by bioarchaeologists as a marker of general population health. However, the sensitivity of growth to environmental effects also makes it likely to be affected by biological mortality bias. The dissertation is composed of four separate scientific papers aimed at examining the effects of biological mortality bias from multiple perspectives. The first paper is a preliminary study contrasting: 1) body length between survivors and non-survivors in a sample of contemporary children; and 2) height and weight between survivors and non-survivors in a diseased sample of girls admitted to a historical tuberculosis sanatorium. The following three papers draw data from a sample of full body post-mortem computed tomography (CT) scans of contemporary children. More specifically, the second paper contrasts dental development between survivors and non-survivors using transition analysis. The third paper presents a protocol for anthropological measurement of long bones in CT scans and reports on its accuracy and replicability. The fourth paper makes use of this protocol for data collection to compare long bone length for age between survivors and non-survivors. Evidence for biological mortality bias is found in linear growth as measured both by full body anthropometrics and long bone lengths, but not in dental development as measured by dental formation stages. These findings reinforce confidence in dental age estimates, but suggest that mortality bias may complicate bioarchaeological analysis of juvenile skeletal remains.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Hugo F.V. Cardoso
Department: 
Environment: Department of Archaeology
Thesis type: 
(Thesis) Ph.D.

‘I don’t want to be alive’: Suicidal ideation and attempted suicide among prison inmates

Author: 
Date created: 
2020-06-12
Abstract: 

Suicide is a serious public health concern and prisoners represent a particularly high-risk group. Though research on the suicidality of prison inmates has gained considerable momentum in recent decades, there are several underexplored areas of inquiry. The purpose of this dissertation was to add knowledge to three underexplored avenues of research. First, very limited research has used a multi-level methodological approach to investigate how both micro-level prisoner and macro-level prison characteristics contribute to suicidal thoughts and behaviour among prison inmates. Second, rates of suicide are highest among middle-aged and older adults; yet, little is known about the nature of suicidal thoughts and attempted suicide among older prison inmates, especially with respect to how they compare to younger counterparts. Third, suicide attempters represent a heterogenous group, whereby repeat-suicide attempters are clinically distinct from single-suicide attempters; however, most prison-based research has examined suicide attempters as a homogenous group, with a paucity of research which has aimed to identify factors that distinguish repeat-suicide attempters from single-suicide attempters. This dissertation used the 2004 Survey of Inmates in State and Federal Correctional Facilities, a cross-sectional survey which collected data on a nationally representative sample of 18,185 prison inmates in the U.S. Results from the first study (Chapter 2) highlight that both micro-level prisoner and macro-level prison characteristics are important to consider as correlates of suicidal thoughts and attempted suicide. This study also highlights variations in predictive patterns for suicidal thoughts versus attempted suicide, as well as gendered patterns with respect to predicting suicidal thoughts/attempts. Results from the second study (Chapter 3) suggest that suicidal thoughts/attempts may manifest differently for younger and older prisoners, with differing patterns of risk. Results from the third study (Chapter 4) emphasize the importance of acknowledging the heterogeneity of suicide attempters, as repeat-suicide attempters potentially possess a differing risk profile as compared to single-suicide attempters. The collective results from this work may be of great use for prison administrators and mental health professionals working in prison settings who want to reduce suicide-related issues or otherwise improve the well-being of at-risk prisoners.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Simon Verdun-Jones
Department: 
Arts & Social Sciences: School of Criminology
Thesis type: 
(Thesis) Ph.D.

Design and validation of genetically encoded probes for the analysis of neuronal catecholamine and ATP co-transmission

Author: 
Date created: 
2019-07-31
Abstract: 

BACKGROUND: Sympathetic nerves co-release several neurotransmitters, including adenosine-5'-triphosphate (ATP) and norepinephrine (NE). Our studies are aimed at understanding how these nerves provide automatic regulation of blood vessel diameter and therefore blood pressure. Relatively little is known at the molecular level about how these nerves control the release of multiple neurotransmitters. Using immunofluorescence microscopy, we recently showed that clusters of vesicles containing ATP and NE are segregated within sympathetic nerve terminals. METHODS: To assess the mechanisms of ATP and NE release, we developed genetically encoded reporters of the vesicular monoamine transporter VMAT2 (SLC18A2) and the vesicular nucleotide transporter VNUT (SLC17A9) tagged with pH-sensitive fluorescent proteins to monitor the release of NE and ATP containing vesicles with molecular specificity and high spatial resolution. RESULTS: First, we characterized the dopaminergic Neuro-2a (N2a) cell line as a model to study catecholamine and ATP co-release. N2a cells express VMAT2 and VNUT, and we found that their expression is upregulated upon differentiation, induced by retinoic acid (RA) and serum deprivation. We optimized retinoic acid and serum concentrations to drive neurite outgrowth while minimizing cell death. Following differentiation, cells exhibited release of VMAT2-pHuji, evoked by field stimulation and the calcium Ionophore 4-Bromo-A23187. Second, we tested whether ATP and NE localize to separate vesicles in N2a cells. Nearest-neighbour colocalization analysis showed that VMAT2 and VNUT are located in common varicosities but in separate vesicles. VNUT and VMAT2 appear to traffic independently, and they appear to be localized into vesicles with pH <6.0 and >7.0, respectively. CONCLUSIONS: Our results corroborate reports that NE and ATP are stored in separate vesicles but segregated into separate pools within the varicosity. The N2a cell line is a promising model to further identify fundamental aspects of differential trafficking and release of VMAT2 and VNUT containing vesicles, while VMAT-pHuji and VNUT-pHluorin permit simultaneous detection of catecholaminergic and purinergic vesicle release.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Damon Poburko
Department: 
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Thesis) M.Sc.

Exploring social presence with a companion scout in virtual reality for arthritic seniors

Author: 
Date created: 
2020-07-20
Abstract: 

Apart from heavy usage in the game industry, Virtual Reality has been gaining focus in recent years in the health world. When it comes down to pain treatment, VR has been proven to be effective for acute pain. However, VR has been inadequately studied regarding its efficacy in dealing with chronic pain, and insufficient explorations have been in place to consolidate best practices. In this direction, a VR environment named LumaPath has been built by the Pain Studies Lab at Simon Fraser University for assisting ageing patients with arthritis with managing their chronic sufferings by motivating them to conduct Range of Motion (RoM) activities, as RoM is an essential component proven to be effective for alleviating arthritic pain symptoms. In the initial version of LumaPath, even when the testing users were indeed motivated to conduct RoM activities, they reported senses of loneliness and uncertainty about what to do. These voices were abstracted as the need for social presence inside VR, hereby defined as the sense of being with another entity delivering verbal or non-verbal information. To mediate LumaPath into a VR environment better for its purpose, this thesis tries to address such need from arthritic seniors (the target users of LumaPath) by first putting forward a list of potential forms of social presence that can be introduced to this VR environmnent, and then chooses a companion scout with navigation capability to move forward with design and implementation. A mixed methods study consisting of quantitative questionnaire and qualitative inquiry is conducted with 16 participants (ages 56-89, 8 females) diagnosed with Rheumatoid Arthritis (RA) and/or Osteoarthritis (OA) to measure to what extent this scout brings a sense of social presence into the scene, reduces a sense of loneliness, and provides guidance inside LumaPath when maintaining the original goal of LumaPath. This thesis discusses the findings regarding the perspectives of arthritic seniors about an assistive virtual character inside a VR environment, their preferences regarding forms of companion and assistance, and concludes with feasible improvements that can be made to the companion scout, preferable ways of providing support inside a VR environment promoting physical activity such as LumaPath, and design directions for creating better immersive environments for the ageing generation with chronic conditions.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Chris Shaw
Department: 
Communication, Art & Technology: School of Interactive Arts and Technology
Thesis type: 
(Thesis) M.Sc.