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.

Indigenous and gender informed approaches to understanding health, social, and mental wellness among indigenous people experiencing homelessness and mental illness in two Canadian cities

Author: 
Date created: 
2020-06-26
Abstract: 

Background: Indigenous people are overrepresented in urban homeless populations internationally, a consequence of racialized policies and structural violence. As a step toward reconciliation Canadian and international policies have recently affirmed Indigenous rights to self-determination. The objective of this dissertation was to identify distinct service needs, gender differences and trajectories to homelessness among Indigenous people in Canada, and to undertake an Indigenous-led process to develop recommendations for action. Methods: Data were drawn from the Vancouver and Winnipeg sites of Canada’s At Home/Chez Soi study. Retrospective analyses were conducted on baseline data from both study sites. Transcripts of interviews with Indigenous participants in Vancouver were thematically analyzed. A traditionally-inspired sharing circle was facilitated by an Indigenous elder and comprised of Indigenous people who had experienced homelessness as well as Indigenous service providers. The sharing circle dialogue employed imagery and symbols to express major themes related to the past and possible future of housing and inclusion among Indigenous peoples. Results: When compared to non-Indigenous participants, Indigenous peoples were more likely to have been homeless at a younger age, to experience ongoing symptoms of trauma, and to have young children. Among Indigenous participants, Indigenous women experienced significantly more symptoms of trauma, higher suicidality, and more experience as victims of violence. Indigenous narratives described situations of intense violence, family disconnection and the lasting harms of generational trauma. Recommendations for action affirmed that government action to promote self-determination is essential. Conclusions: This dissertation documents the distinct historical and current character of Indigenous homelessness, and the need to transform colonial practices that oppress Indigenous Canadians, particularly women and young people. Community developed recommendations for action emphasized the urgent need for practices that promote self-determination and strengthen the resurgence of Indigenous culture.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Julian Somers
John O'Neil
Department: 
Health Sciences: Faculty of Health Sciences
Thesis type: 
(Thesis) Ph.D.

Modeling human decision-making in spatial and temporal systems

Author: 
Date created: 
2020-08-20
Abstract: 

In this thesis, we analyze three applications of human decision-making in spatial and temporal environments. The first two projects are statistical applications to basketball while the third project analyzes an experiment that aims to understand decision-making processes in games. The first project explores how efficiently players in a basketball lineup collectively allocate shots. We propose a new metric for allocative efficiency by comparing a player's field goal percentage (FG%) to their field goal attempt (FGA) rate in context of both their four teammates on the court and the spatial distribution of their shots. Leveraging publicly available data provided by the National Basketball Association (NBA), we estimate player FG% at every location in the offensive half court using a Bayesian hierarchical model. By ordering a lineup's estimated FG%s and pairing these rankings with the lineup's empirical FGA rate rankings, we detect areas where the lineup exhibits inefficient shot allocation. Lastly, we analyze the impact that suboptimal shot allocation has on a team's overall offensive potential, finding that inefficient shot allocation correlates with reduced scoring. In the second basketball application, we model basketball plays as episodes from team-specific nonstationary Markov decision processes (MDPs) with shot clock dependent transition probabilities. Bayesian hierarchical models are employed in the parametrization of the transition probabilities to borrow strength across players and through time. To enable computational feasibility, we combine lineup-specific MDPs into team-average MDPs using a novel transition weighting scheme. Specifically, we derive the dynamics of the team-average process such that the expected transition count for an arbitrary state-pair is equal to the weighted sum of the expected counts of the separate lineup-specific MDPs. We then utilize these nonstationary MDPs in the creation of a basketball play simulator with uncertainty propagated via posterior samples of the model components. After calibration, we simulate seasons both on policy and under altered policies and explore the net changes in efficiency and production under the alternate policies. We also discuss the game-theoretic ramifications of testing alternative decision policies. For the final project, we take a different perspective on the behavior of the decision-makers. Broadly speaking, both basketball projects assume the agents (players) act sub-optimally and the goal of the analyses is to evaluate the impact their suboptimal behavior has on point production and scoring efficiency. By contrast, in the final project we assume that the agents' actions are optimal, but that the criteria over which they optimize are unknown. The goal of the analysis is to make inference on these latent optimization criteria. This type of problem can be termed an inverse decision problem. Our project explores the inverse problem of Bayesian optimization. Specifically, we seek to estimate an agent's latent acquisition function based on their observed search paths. After introducing a probabilistic solution framework for the problem, we illustrate our method by analyzing human behavior from an experiment. The experiment was designed to force subjects to balance exploration and exploitation in search of a global optimum. We find that subjects exhibit a wide range of acquisition preferences; however, some subject's behavior does not map well to any of the candidate acquisitions functions we consider. Guided by the model discrepancies, we augment the candidate acquisition functions to yield a superior fit to the human behavior in this task.

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

Do adolescent risk assessment tools capture self-reported reasons for desistance? An examination of the content validity of protective factors

Date created: 
2020-08-11
Abstract: 

Although prior research has examined the predictive validity of risk assessment tools, research on their content validity is limited. The present study used a novel approach to assess evidence for the content validity of three adolescent risk assessment tools that include protective factors: the Structured Assessment of Violence Risk in Youth (SAVRY; Borum et al., 2006), the Structured Assessment of Protective Factors for Violence Risk – Youth Version (SAPROF-YV; de Vries Robbé et al., 2015), and the Short-Term Assessment of Risk and Treatability: Adolescent Version (START:AV; Viljoen et al., 2014). This study investigated whether the protective factors included on these tools captured information that people with a history of adolescent offending (n = 103) described as relevant to their desistance from offending. Desistance criteria followed previous qualitative research and included self-reported desistance for a period of at least two years. Data was collected from two samples, through an in-person interview study and an online survey study. Participants were asked open-ended questions about their desistance, followed by direct questions based on the specific protective factors on the tools. Responses were coded using qualitative directed content analyses based on the tools’ operational definitions for each item. Findings generally provided support for the content validity of the tools. Responses were also coded inductively to identify additional reasons for desistance that were not captured by the tools. Although four other themes emerged, they may be partially captured under existing items or may be included as case-specific factors. Due to the debate about the distinctiveness of protective and risk factors, this study also examined whether factors are described in terms of the presence of a protective factor or in terms of the removal of a risk factor. Reasons for desistance were primarily discussed in terms of the presence of protective factors. Overall the findings provide evidence to support the item content included on the SAVRY, SAPROF-YV, and START:AV, and highlight the value of considering client/patient perspectives in risk assessment research.

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

Panic! In the suburbs: Investigating moral configurations of risk, neoliberal rationality, and middle-class anxiety in Maple Ridge B.C.

Author: 
Date created: 
2020-07-27
Abstract: 

In this thesis, I examine how the emergence of a homeless encampment in Maple Ridge, British Columbia in 2017 produced a reaction that I argue was the result of a moral panic. I seek to understand how a homeless encampment, as a hyper visible, centralized, and politically active hub for a marginalized community contributed to the sense of urgency around homelessness. I draw upon moral panic scholarship including theories around risk, neoliberal rationality, and the attending hybrid moral configurations produced by both to account for the hyper emotional reaction to homelessness in Maple Ridge. I situate this panic within the development of neoliberal disciplinary mechanisms that compel individuals to internalize ways of being that reimagine their relationship to the state and implore them to manage the conduct of others accordingly. Finally, I argue that this event was produced by a latent anxiety around economic precarity within middle class suburban communities.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Dany Lacombe
Department: 
Arts & Social Sciences: Department of Sociology and Anthropology
Thesis type: 
(Thesis) M.A.

A de novo nucleoside synthesis and late-stage heterobenzylic fluorination strategy

Author: 
Date created: 
2020-07-30
Abstract: 

Nucleoside analogues constitute almost half of today’s major anticancer and antiviral therapeutics. Despite this, synthetic routes to these valuable molecules have typically relied on carbohydrate starting materials, which can significantly impair efforts in medicinal chemistry. Moreover, nucleoside scaffolds with increased complexity (e.g., C2’ or C4’ substitution) often require lengthy syntheses (up to 18 steps). Toward a goal of streamlining nucleoside synthesis, we have developed a one-pot proline-catalyzed α-fluorination/aldol reaction that generates enantiomerically enriched fluorohydrins that can serve as versatile building blocks for the construction of nucleoside analogues. Most importantly, this process enables access to variously functionalized nucleoside analogues in only 3 steps from commercial starting materials. The development of this process and practical application in rapidly accessing C2’- and C4’- modified nucleoside analogues, locked nucleic acids (LNAs), and iminonucleosides should inspire future efforts in drug design. Similar challenges also obstruct the synthesis of carbohydrate analogues (CAs), another important class of molecules to drug discovery efforts. To streamline CA synthesis, we developed several new proline-catalyzed α-functionalization/aldol reactions for constructing stereochemically rich and densely functionalized aldol adducts. In only 2 steps, these aldol adducts were then readily converted into a structurally diverse collection of CAs including iminosugars, annulated furanoses, bicyclic nucleosides, and fluorinated carbacycles. Incorporation of a fluorine atom can have several profound effects on a drug’s physiochemical properties – including metabolic stability, membrane permeability, and potency. However, the introduction of fluorine into the heterobenzylic position of drug molecules has remained an unsolved synthetic challenge. Towards this goal, we describe the first unified platform for the late-stage mono- and difluorination and trifluoromethylthiolation at heterobenzylic positions. This technology should become a dynamic tool for drug-lead diversification.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Robert Britton
Department: 
Science: Department of Chemistry
Thesis type: 
(Thesis) Ph.D.

Cannabidiol (CBD) marketing and decision-making: Examining 164 crowdfunding campaigns and 2,165 CBD products for sale online in Canada

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

The popularity of cannabidiol (CBD) has increased dramatically due to medical perceptions of CBD as a “cure-all”, with over 1,000 products available. Limited research examines how consumers find and decide to purchase CBD for medical purposes. First, to understand motivations for CBD medical use, 164 GoFundMe.com campaigns incorporating CBD for a medical condition are thematically examined. Second, to understand how CBD is presented to potential consumers, 2,165 CBD products on Canadian websites are analyzed. The resulting findings suggest that among crowdfunders, CBD is identified as a treatment through self-directed research, a recommendation by a trusted care provider, or experiential insights from someone associated with or influencing the personal network. Product descriptions frame CBD as a treatment or cure for specific ailments, a natural health product, or a product used in specific ways to achieve particular results. These findings suggest the need for systematic auditing of CBD products for regulatory adherence.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Jeremy Snyder
Department: 
Health Sciences: Faculty of Health Sciences
Thesis type: 
(Thesis) M.Sc.

Discovery of a novel tumor suppressor from the autophagy regulatory network: LRRK2 in lung adenocarcinoma

Author: 
Date created: 
2019-08-14
Abstract: 

(Macro)autophagy captures, degrades and recycles cytoplasmic components and organelles, via fusion of double-membraned autophagosomes with lysosomes. Basal autophagy is homeostatic, while increased rates of autophagy are stress adaptive. Autophagy is a potent tumor cell survival mechanism during stress, while in pre-malignant cells, it can provide a barrier against transformation. Mechanisms of autophagic cytoprotection and tumor promotion are established in preclinical models; however, whether the autophagy pathway is a target for recurrent molecular alteration in patient tumors remains unknown. I present a survey of 211 human autophagy-associated genes for tumor-related alterations to DNA sequence and RNA expression levels and an examination of their association with patient survival outcomes, in multiple cancer types with publicly available sequence data from The Cancer Genome Atlas (TCGA) consortium. In general, the core autophagy machinery was not a target of recurrent mutation in patients; therefore, the pathway remains functional and exploitable for tumor cell survival. However, autophagy regulators were targets of recurrent mutation and dynamic expression ─ between specific patient groups, in select cancers. Hence, context-dependent autophagy regulation contributes to tumor heterogeneity in patients. I further established that knockout of LRRK2, a previously described autophagy modulator that appears transcriptionally repressed in TCGA lung adenocarcinoma (LUAD), increased tumor initiation in a murine model of carcinogen-driven lung cancer. LRRK2 is an overactive kinase in Parkinson’s disease (PD) and LRRK2 inhibition in primates produces immature lamellar bodies in a main LUAD cell-of-origin. Lamellar bodies are lysosome-related secretory organelles that exocytose pulmonary surfactant, a mixture of phospholipids and lipoproteins key to innate lung defence. In TCGA LUAD patients, reduced LRRK2 was associated with current smoking, worse overall survival, genomic instability and gene signatures of poor differentiation, reduced surfactant metabolism and immunosuppression. LRRK2 was recently identified as an alveolarization gene in mouse lung development. I identified shared transcriptional signals of increased proliferation concomitant with decreased surfactant metabolism, in LRRK2-low LUAD and postnatal alveolar septation in mice, suggesting aberrant activation of a cell-of-origin developmental program in these tumors. I conclude that LRRK2 has tumor suppressive properties in LUAD, warranting further consideration for LRRK2 inhibition strategies in PD.

Document type: 
Thesis
Supervisor(s): 
Sharon Gorski
Department: 
Science: Department of Molecular Biology and Biochemistry
Thesis type: 
(Thesis) Ph.D.

Expanding non-natural chemical space through synthetic diversification of natural product extracts

Author: 
Date created: 
2019-08-07
Abstract: 

Natural products are structurally diverse compounds that often possess biological activity, making them the most prominent source for the discovery and development of drugs. Existing discovery methods often lead to the re-discovery of known compounds, causing the pharmaceutical industry to deprioritize natural products as a source of drug leads. Examination of natural products chemical space indicates that there are gaps that have yet to be filled in, suggesting that new methods are needed expand chemical space to access novel chemistry. This work expands chemical space by using synthetic transformations to derivatize natural product extracts. A library of 540 prefractionated derivatized natural product extracts was generated and screened against bacterial pathogens and cancer cells. A change in the antimicrobial and anticancer activity was observed as a result of the derivatizations. Derivatization of extract via a strain release reaction produced a novel staurosporine derivative with increased activity against human osteosarcoma cells.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Roger Linington
Department: 
Science: Department of Chemistry
Thesis type: 
(Thesis) M.Sc.

Navigating the femininity-vulnerability nexus: A reconsideration of the protective function of gendered “safety work”

Author: 
Date created: 
2019-08-06
Abstract: 

Based on Critical Discourse Analysis of 17 interviews with women aged 19-26, this thesis explores the ways women negotiate positionalities as subjects of a gendered fear discourse that, while exaggerating gendered risks in public spaces, paradoxically places the onus on women to ensure their own safety. Findings suggest that, while fear of violent crime (FoVC) contours nearly every aspect of women’s lives and engenders taxing “safety work”, gendered “risk-management” is naturalized by participants as a sensical response to “immutable” gendered vulnerability. Although ostensibly engaged to ensure physical security, safety work only exacerbates women’s FoVC and unreliably mitigates their exposure to violence. I thus suggest that, in the present research, safety work is engaged because it affords women the ontological security associated with evading the subjectivity of the “Imprudent Woman”: the failed female subject whose inadequate “risk-management” justifiably denies her care, trust, and even access to the resources required for living.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Wendy Chan
Department: 
Arts & Social Sciences: Department of Sociology and Anthropology
Thesis type: 
(Thesis) M.A.

High-resolution digital soil mapping for managed forests using airborne LiDAR data

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

A goal of sustainable forest management using digital soil mapping (DSM) is to ensure that current and future generations have the best soil information so they can use forest resources wisely. This goal can be achieved using new technologies of generating digital soil maps and high-resolution light detection and ranging (LiDAR) data. Uncertainty in digital soil maps can be quantified using quantile regression (QR). The overall objective of this study is to generate several digital soil maps using different machine learning (ML) methods for forest management purposes and use a QR method to estimate their uncertainty. The study area is the Eagle Hill Forest (95 km2), located west of Kamloops, BC, Canada. Five soil properties were mapped and locations with soil erosion, displacement, and compaction and puddling hazards were displayed on maps and discussed. 90% prediction interval (PI) maps were produced and the performance of the QR method in uncertainty quantification of different ML models was illustrated by producing Prediction Interval Coverage Probability (PICP) plots.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Margaret Schmidt
Department: 
Environment: Department of Geography
Thesis type: 
(Thesis) M.Sc.