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.

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.

Inverse reinforcement learning for team sports: Valuing actions and players

Author: 
Date created: 
2020-06-15
Abstract: 

A major task of sports analytics is to rank players based on the impact of their actions. Recent methods have applied reinforcement learning (RL) to assess the value of actions from a learned action value or Q-function. A fundamental challenge for estimating action values is that explicit reward signals (goals) are very sparse in many team sports, such as ice hockey and soccer. This paper combines Q-function learning with inverse reinforcement learning (IRL) to provide a novel player ranking method. We treat professional play as expert demonstrations for learning an implicit reward function. Our method alternates single-agent IRL to learn a reward function for multiple agents; we provide a theoretical justification for this procedure. Knowledge transfer is used to combine learned rewards and observed rewards from goals. Empirical evaluation, based on 4.5M play-by-play events in the National Hockey League (NHL), indicates that player ranking using the learned rewards achieves high correlations with standard success measures and temporal consistency throughout a season.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Oliver Sculte
Department: 
Applied Sciences: School of Computing Science
Thesis type: 
(Thesis) M.Sc.

Nonsuicidal self-injury-relief associations over the course of dialectical behaviour therapy

Author: 
Date created: 
2020-07-17
Abstract: 

I examined the relationship between the strength of a cognitive nonsuicidal self-injury (NSSI)-relief association and NSSI over time in the context of dialectical behaviour therapy (DBT) among individuals with borderline personality disorder (BPD). Self-injuring individuals with BPD were assessed for BPD and NSSI and randomly assigned to 6 or 12 months of comprehensive, standard DBT. Participants were re-assessed for NSSI every 3 months from the start of therapy for 24 months. The NSSI-relief association was assessed at baseline and again at 6 and 12 months after the start of therapy via the deliberate self-harm implicit association test (DSH IAT; Gratz et al., 2016). At baseline, participants also completed a measure of their motives for NSSI. Hypothesis 1 was that, at baseline, lifetime NSSI would be positively associated with the NSSI-relief association beyond self-reported emotion relief motives. Hypothesis 2 was that the NSSI-relief association would weaken over the course of one year after treatment began. Hypothesis 3 was that the NSSI-relief association at baseline would predict the rate of change of NSSI from baseline to the end of one year, such that a stronger NSSI-relief association would predict a slower rate. Hypothesis 3a was that the rate of change of NSSI from baseline to the end of one year would predict the rate of change of the NSSI-relief association from baseline to the end of one year, such that a greater rate of change of NSSI would predict a greater rate of change of the NSSI-relief association. Analyses revealed that lifetime NSSI was not associated with the NSSI-relief association beyond self-reported emotion relief motives. As well, the NSSI-relief association did not weaken over the course of one year. Finally, findings from parallel linear growth curve models did not support hypothesis 3 or 3a. These results suggest that the DSH IAT might not be sensitive to treatment effects in DBT for individuals with BPD in clinical populations. Findings also suggest that future research should investigate change in other processes that maintain NSSI, the association between DSH IAT D scores and NSSI consequences, and the relationship between NSSI and relief over time.

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

The archaeological foodscape of Roman Kent and Essex

Author: 
Date created: 
2020-08-07
Abstract: 

The material manifestations of the colonial encounters occurring in Roman Britain has been subjective to diverse – and divisive – theoretical and methodological considerations. Situated within this ongoing discourse, this thesis employs occurrence and network analysis to investigate the impact of these colonial encounters in the foodscape of Early Roman Britain. Archaeobotanical and zooarchaeological data were collected from reports of Roman excavations throughout the counties of Kent and Essex. Occurrence analysis was conducted using a site-type approach to reveal differences in plant and animal-based food occurrence. The imported plant foods data were visualized utilizing network analysis. This project reveals that while all site-types had some access to new foodstuffs following conquest, nucleated settlements and villas exhibited more frequent occurrence and greater diversity than the rural sites. The site-type differences in food availability/usage are interpreted as distinct forms of entanglement resulting from the colonial encounters, restructuring the British foodscape.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Sabrina Higgins
Department: 
Environment: Department of Archaeology
Thesis type: 
(Thesis) M.A.

Exploring the use of telepresence robots in long distance relationships

Author: 
Date created: 
2020-06-22
Abstract: 

This thesis explores the use of telepresence robots as a communication tool for long distance relationships. While communication between partners can be nuanced and varied, current remote communication tools are limited in the aspects of communication that are supported. The lack of an embodiment creates challenges for maintaining relationships over distance because communication becomes limited to audiovisual interactions. The telepresence robot provides an embodiment through which long distance partners can interact, opening up unique opportunities for engagement. This work explores how real world couples utilize telepresence robots to interact over distance and considers how the findings translate to design implications and considerations. This thesis presents the following three studies in a cumulative format. The first study looks at how telepresence robots are used by long distance couples in the home space. This exploratory field study utilized interviews to collect data while minimizing intrusiveness in the home space. The second study compares the use of telepresence robots versus tablets for the joint activity of shopping as long distance couples. This between-groups study used data from observations and interviews. The third study explores the use of a telepresence robot when paired with voice-controlled devices in a home shared over distance. This autobiographical study collected daily diaries, interviews, and photo/video materials for data. This collection of studies contributes early insights on the use of telepresence robots by long distance couples to support their uniquely demanding communication needs. My findings show that couples use telepresence robots during evening and weekends to spend time together, with the freedom to move around independently. The telepresence robot supports the sense of a shared home and lets partners participate in everyday life. Movement supports not only independence, but also displays of personality and playfulness. This work also underscores the limitations of an appendage-free design, which constrains helpful acts and joint activities. I include a chapter on design considerations before the conclusion chapter. There I discuss the importance of supporting a sense of belonging and ownership in the shared home home space, and a sense of joint participation and variety in activities.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Carman Neustaedter
Department: 
Communication, Art & Technology: School of Interactive Arts and Technology
Thesis type: 
(Thesis) Ph.D.

A proposed methodology for investigating chatbot effects in peer review

Author: 
Date created: 
2020-07-24
Abstract: 

Teaching academic writing skills consumes a lot of time for teachers. One way to save some of this time and support students’ development of writing skills is to supplement teacher-student interaction with a chatbot. I developed such a chatbot, DD, to help post-secondary writers develop a thesis statement for an argumentative essay and to improve their feedback when in the role of a peer reviewer of classmates’ draft essays. The study analyzes student-chatbot interactions in a lower division course as background for developing methodological procedures that examine students’ engagement patterns with a chatbot. Analyses of student-chatbot data reveal students participating in this study tended to be overconfident about their learning. Furthermore, students reported a positive experience when they conversed with the chatbot. Several pedagogical implications for chatbot-guided writing instructions and uses of learning technology are addressed.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Philip H. Winne
Department: 
Education: Faculty of Education
Thesis type: 
(Thesis) Ph.D.

From empty to angry: Extremism, modernity, and the search for identity

Author: 
Date created: 
2020-06-15
Abstract: 

An increase in the amount of high-profile incidents and attacks in the West perpetrated by individuals subscribing to a variety of extremist ideologies over the past decade has led to an influx of academic research concerned with uncovering how and why it is that individuals become radicalized toward ideologically-motivated extremist violence. While such research has examined a diverse range of social, demographic, and psychological variables and their potential link/correlation to the radicalization process, there has yet to emerge an accurate or reliable ‘profile’ with respect to who is more or less likely to become radicalized or join extremist/terrorist movements. The primary aim of this dissertation is to present a novel theoretical approach which centers the concept of individual identity as the fundamental factor which drives individuals in the West toward involvement with extremist movements. This theory of identity, which presupposes that macro-level structural factors fundamentally dictate how individuals experience and internalize identity on a micro-level, is outlined by tracing how the concept of ‘identity’ has historically evolved in ‘Western’ culture up to its current iteration in modern, hyper-connected, late-capitalist society. Once outlined, this theory of identity is empirically applied to the digital media content of two extremist movements via a mixed-method approach that utilizes topic modelling, sentiment analysis, and thematic/discourse analysis. More specifically, the content of the so-called Islamic State (including videos, magazines, and Twitter posts) and the user-generated comments of the notorious far-right online community r/The_Donald are examined through this theoretical lens and analyzed with this mixed-method approach. Results indicate that, wittingly or not, modern extremist movements routinely incorporate questions of identity into both their propaganda and general discussions in a manner that provides simplistic solutions and answers to the complex problems of identity and self that are created and amplified within modern Western culture. As such, this dissertation argues that the attraction of extremist ideology and the potential for extremist violence is, at current, an inevitable byproduct of modern macro-level structural and economic conditions.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Richard Frank
Department: 
Arts & Social Sciences: School of Criminology
Thesis type: 
(Thesis) Ph.D.