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.

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.

An investigation of profiles of polysubstance use in homeless & precariously housed individuals

Author: 
Date created: 
2020-07-02
Abstract: 

Despite the prevalence of polysubstance use among homeless and precariously housed persons, the cognitive and functional consequences of substance use patterns are poorly understood. This may be due in part to the limitations of existing work that attempts to isolate substances (e.g. methodologically or statistically) or lacks granularity (e.g. cross-sectional or lacking frequency of use). As such, this study aimed to improve upon past work by evaluating naturally occurring patterns of polysubstance use longitudinally. Using cluster analysis, this study revealed three validated substance use profiles: Frequent Heroin with Moderate Methamphetamine Use, Frequent Cannabis Use, and Infrequent to Moderate Polysubstance Use. Mixed general linear models indicated that the use profiles were not associated with differences in cognitive trajectory or capacity, however, persons engaged in frequent use showed poorer social and occupational functioning compared to a moderate use group. Implications are discussed.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Allen Thornton
Department: 
Arts & Social Sciences: Department of Psychology
Thesis type: 
(Thesis) M.A.

Technical development of the brain vital signs framework as an objective and practical test for concussion

Author: 
Date created: 
2020-06-24
Abstract: 

The engineering design criteria for an objective test for concussion dictate that it should be rapid, portable, practical, robust, and sensitive over the time-course of injury. This is an important technical challenge, which is yet to be solved. Currently, sports medicine professionals who treat concussions are limited by a lack of access to objective measurement tools for evidence-based treatment. Electroencephalography-based technologies present a unique opportunity to address these criteria. The brain vital signs framework uses electroencephalography to rapidly assess electrical brain responses to auditory stimuli and make interpretations on cognitive changes. However, applications in electroencephalography are typically recorded under controlled laboratory conditions and have not been validated under the uncontrolled, noisy environments necessary to evaluate concussions. These clinical and athletic environments are fundamentally different to those found in the laboratory and have a unique set of constraints that make traditional methods impractical. This thesis addresses the technical challenges to demonstrate that the brain vital signs framework can be used as an objective, practical tool for monitoring concussion. First, the brain vital signs framework was successfully deployed in a clinical environment. Markers of brain function demonstrated significant concussion-related changes in athletes that were undetected by standard concussion protocols. This is the first demonstration of a portable brain technology being implemented immediately at the point of care for concussion. However, there are additional technical challenges to improve the practicality of this framework. Subsequently, an automated framework for numerically assessing the signal quality of electroencephalography is presented. This framework is highly sensitive and specific to classifying artifacts and can approximate the signal-to-noise-ratio of a recorded signal. Finally, a new approach for recording event-related potentials from distant sensor locations is presented to optimise the speed and practicality of portable brain technologies. The presented body of work incorporates novel engineering developments to provide robust, technical solutions for a clinical problem. These are impactful and important results that will allow for improved medical applications in concussion.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Ryan D'Arcy
Department: 
Applied Sciences: School of Engineering Science
Thesis type: 
(Thesis) Ph.D.

Modelling the effect of Canada's clean fuel standard on greenhouse gas emissions

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

Canada is projected to miss its 2030 greenhouse gas (GHG) emissions target. Consequently, there remain federal policies that have been announced but not yet implemented that aim to close the 2030 “emissions gap”. This study assesses the likely effects of one such policy, the Clean Fuel Standard (CFS), on GHG emissions using the gTech energy-economy model, with a focus on the importance of policy interactions as they relate to the CFS’s GHG abatement potential. The study finds that Canada’s CFS as proposed would cause about 7Mt of GHG emissions reductions by 2030 when added to other planned and implemented climate policies. An exploratory method for quantifying GHG emissions reductions “overlap” between climate policies is developed. The results emphasize the importance to analysts and policy makers of accounting for both the incremental and combinatory effects of different types of interacting climate polices.

Document type: 
Graduating extended essay / Research project
File(s): 
Supervisor(s): 
Mark Jaccard
Department: 
Environment: School of Resource and Environmental Management
Thesis type: 
(Project) M.R.M.

Statistical machine learning in computational genetics

Author: 
Date created: 
2020-07-03
Abstract: 

Statistical machine learning has played a key role in many areas, such as biology, health sciences, finance and genetics. Important tasks in computational genetics include disease prediction, capturing shapes within images, computation of genetic sharing between pairs of individuals, genome-wide association studies and image clustering. This thesis develops several learning methods to address these computational genetics problems. Firstly, motivated by the need for fast computation of genetic sharing among pairs of individuals, we propose the fastest algorithms for computing the kinship coefficient of a set of individuals with a known large pedigree. {Moreover, we consider the possibility that the founders of the known pedigree may themselves be inbred and compute the appropriate inbreeding-adjusted kinship coefficients, which has not been addressed in literature.} Secondly, motivated by an imaging genetics study of the Alzheimer's Disease Neuroimaging Initiative, we develop a Bayesian bivariate spatial group lasso model for multivariate regression analysis applicable to exam the influence of genetic variation on brain structure and accommodate the correlation structures typically seen in structural brain imaging data. We develop a mean-field variational Bayes algorithm and a Gibbs sampling algorithm to fit the model. We also incorporate Bayesian false discovery rate procedures to select SNPs. The new spatial model demonstrates superior performance over a standard model in our application. Thirdly, we propose the Random Tessellation Process (RTP) to model complex genetic data structures to predict disease status. The RTP is a multi-dimensional partitioning tree with non-axis aligned cuts. We develop a sequential Monte Carlo (SMC) algorithm for inference. Our process is self-consistent and can relax axis-aligned constraints, allowing complex inter-dimensional dependence to be captured. Fourthly, we propose the Random Tessellation with Splines (RTS) to acquire complex shapes within images. The RTS provides a framework for describing Bayesian nonparametric models based on partitioning two-dimensional Euclidean space with splines. We also develop an inference algorithm that is "embarrassingly parallel". Finally, we extend the mixtures of spatial spline regression with mixed-effects model under the Bayesian framework to accommodate streaming image data. We propose an SMC algorithm to analyze online fashion brain image.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Liangliang Wang
Department: 
Science: Department of Statistics and Actuarial Science
Thesis type: 
(Thesis) Ph.D.

Can collaborative giving boost generosity?

Author: 
Date created: 
2020-07-16
Abstract: 

People often make charitable donations together with others, from strangers to romantic partners. Do people donate more generously when they give collaboratively with others? Past work has been largely correlational, mixed, and limited. To overcome prior empirical shortcomings, I conducted two well-powered, pre-registered experiments to test whether collaborative giving boosts generosity while also exploring its interpersonal and emotional consequences. In Study 1 (N =202; 101 dyads) and Study 2 (N =310; 155 dyads), pairs of unacquainted undergraduate peers earned money for evaluating a charitable advertisement. Then, I randomly assigned pairs to donate either collaboratively (Studies 1-2), individually in the presence of one another (Studies 1-2), or privately (Study 2). In both studies, I observed no differences in generosity across conditions. However, collaborative (vs. individual) giving boosted generosity through greater intrinsic enjoyment. Additionally, collaborative (vs. individual) giving facilitated social bonds between peers. Practical and theoretical insights are discussed.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Lara Aknin
Department: 
Arts & Social Sciences: Department of Psychology
Thesis type: 
(Thesis) M.A.

Classroom teachers’ perspectives of school-based team (SBT) practices in British Columbia

Author: 
Date created: 
2020-06-03
Abstract: 

Classroom teachers today maintain a powerful role in educating an increasingly diverse student population in the midst of changing socio-political climates, educational policies, and limited economic funds. Balancing the need to support students who may have special needs to achieve their individual potential, amidst this context can be challenging for many teachers today. In order to alleviate some of the challenges and pressures teachers face in educating diverse student needs, school-based teams (SBTs) exist in many schools in British Columbia (B.C.) to support teachers with developing the necessary instructional expertise and to identify potential special needs in students. Despite the purpose of SBTs, many classroom teachers report that school team practices are ineffective and largely disconnected from the practical realities of teaching diverse students (Doll et al., 2005; Lane, 2013; Young & Gaughan, 2010). To understand teachers’ experiences and perspectives of SBT practices in the specific context of a large and diverse school district in B.C., I interviewed 15 elementary teachers who had previous experiences teaching students with special needs in the classroom and who had referred their students to SBTs. In their interviews, classroom teachers’ responses uncovered a dissonance that exists between SBT policy and practice. In analyzing their interview responses, I found three key themes: (a) The instructional recommendations made by SBTs are ineffective, (b) There is a lack of funding and resources to implement SBT decision outcomes, and (c) Classroom teachers’ professional judgement was not given the consideration it deserved by SBT members. By using key ideas from Ball et al.’s (2012) conceptual framework for policy enactment to illuminate the findings of this study, I conclude that the “material,” “interpretive,” and “discursive” components of policy enactment play an important role in revealing why tensions exist between SBT policy and practice. The findings of this study suggest that the special education practices in the Rosendale School District need further attention.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Rebecca Cox
Department: 
Education: Faculty of Education
Thesis type: 
(Thesis) Ed.D.

Omni channel and Canadian ethnic media: A critical case study of third language broadcasting policy

Author: 
Date created: 
2019-12-06
Abstract: 

The foundations of the Canadian broadcasting system are pillared by the recognition of Canadian culture through language. The Canadian Radio-Television and Telecommunications Commission (CRTC) recognizes this by setting minimum broadcasting content requirements for Canada’s English, French, Métis and First Nation’s language on Canadian television channels. What is exempt from this requirement is the remaining media: the ethnic or third language media. This investigation set out to review the history of ethnic media policy from 2007 to 2019 through a case study of the OMNI multicultural channel because of its significant role as the largest multicultural and multilingual media company in Canada. Findings of this case identify policy gaps that question how well CRTC regulations serve the Canadian ethnic media audience. This study has identified key CRTC broadcasting notices and public hearings for close documentary analysis to create a case study timeline for ethnic media programming. Results of this investigation show how private ethnic media companies, such as OMNI, are tailoring their broadcasting schedules to benefit from their Category A channel statuses; yet, fail to challenge the status quo to meet the rapidly changing needs of the ethnic media audience. Audience competition for licensed programming, new media and a globalized media environment is evolving with technological developments that do not support the existing ethnic media programming model. The findings will be of interest to key broadcasting private media companies, advertisers and ethnic media audiences that benefit from the Canadian third language programming. News media is valuable for community building, but there is an informational gap for Canadians who remain uninformed due to language barriers. New media and globalization shed a new light on the future of programming for the Canadian ethnic audiences and Canadian broadcasting policies.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Alison Beale
Department: 
Communication, Art & Technology: School of Communication
Thesis type: 
(Thesis) M.A.

Sex differences in coordinated brain activity in clinical child populations

Date created: 
2020-07-08
Abstract: 

A disruption of normal brain development during early stages of life has been associated with higher male vulnerability expressed by male preponderance among affected individuals and/or more severe impairments in males for developmental disorders. Although this phenomenon is frequently acknowledged by the scientific community, its neurophysiological underpinnings remain largely unclear. In this thesis I investigate male vulnerability in very preterm children and individuals with Autism Spectrum Disorder (ASD). Both clinical child populations entail early developmental adversity leading to behavioural and cognitive alterations, believed to be elicited, in part, by disrupted communication between brain areas. Therefore, I examine resting state whole-brain connectivity and its developmental changes in these clinical populations using fMRI and MEG and test the hypothesis of sex-specific connectivity differences between males and females resulting in male disadvantage. In the first study I investigate sex differences in interhemispheric homotopic connectivity and its developmental trajectories in participants with ASD as well as in typically developing individuals. Our findings demonstrate differences in developmental trajectories rather than connectivity. Both females and males with ASD deviate from typical female trajectories while expressing similar developmental trajectories to typical males. In the second study I examine local connectivity and its age-related changes using a similar cohort of participants. Group and sex differences are observed in both local connectivity and its developmental trajectories. Females with ASD are characterised by more robust alterations. Lastly, in the third study I test the hypothesis that male vulnerability in very preterm children can be detected as more pronounced alterations in inter-regional connectivity in boys compared to girls. Our results confirm this hypothesis suggesting that connectivity alterations might contribute to male disadvantage reflected in long-term behavioural and cognitive outcome. Overall, this thesis highlights that disruptions in brain connectivity and/or its developmental trajectories differ between males and females with altered early development supporting the existence of female protective features preventing females from developing pathological outcome.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Sam Doesburg
Department: 
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Thesis) Ph.D.