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.

Modelling Fine Particulate Matter Concentrations inside the Homes of Pregnant Women in Ulaanbaatar, Mongolia

Author: 
Date created: 
2017-06-30
Abstract: 

Fine particulate matter (PM2.5) is a leading public health risk factor globally. Indoor concentrations are an important determinant of exposure because people spend the majority of time indoors. I developed models for predicting PM2.5 concentrations inside the homes of pregnant women in Ulaanbaatar, Mongolia. The work was part of a randomized controlled trial of portable air cleaner use during pregnancy, fetal growth, and early childhood development. Multiple linear regression (MLR) and random forest regression (RFR) were used to model indoor PM2.5 concentrations using 7-day indoor PM2.5 measurements and potential predictors obtained from outdoor monitoring data, questionnaires, home assessments, and geographic data sets. The MLR (R2 = 50.5%) and RFR (R2 = 47.8%) models explained a moderate amount of variation in log-transformed indoor PM2.5. Model predictions can be used to evaluate associations between indoor PM2.5 concentrations during pregnancy and development in early life.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Ryan Allen
Department: 
Health Sciences: Faculty of Health Sciences
Thesis type: 
(Thesis) M.Sc.

Recommendation in Social Media: Utilizing Relationships among Users to Enhance Personalized Recommendation

Author: 
Date created: 
2017-06-29
Abstract: 

Recommender systems are ubiquitous in our digital life in recent years. They play a significant role in numerous Internet services and applications such as electronic commerce (Amazon and eBay), on-demand video streaming (Netflix and Hulu). A key task in recommender systems is to model user preferences and to suggest, for each user, a personalized list of items that the user has not experienced, but are deemed highly relevant to her. Many of these recommendation algorithms are based on the principle of collaborative filtering, suggesting items that similar users have consumed. With the advent of online social networks, social recommendation has become one of the most popular research topics in recommender systems, exploiting the effects of social influence and selection in social networks, where user relationships are explicit, i.e., there will be an edge connecting two users if they are friends. In addition, more information about the relationships between users in social media becomes available with the rapid development of various Internet services. For example, more and more online web services are providing mechanisms by which users can self-organize into groups with other users having similar opinions or interests, enabling us to analyze the interactions between users with others insides/outsides groups, as well as the engagement between users and groups. User relationships in these applications are usually implicit and can only be utilized indirectly for recommendation tasks. In this thesis, we focus on utilizing user relationships (either explicit or implicit) to enhance personalized recommendation in social media. We study three problems of recommendation in social media, i.e., recommendation with strong and weak ties, social group recommendation and interactive social recommendation in an online setting. We propose to improve social recommendation by incorporating the concept of strong and weak ties which are two well documented terms in the social sciences, boost the performance of social group recommendation through modeling the temporal dynamics of engagement of users with groups, and tackle the interactive social recommendation problem via employing the exploitation-exploration strategy in an online setting. Our proposed models are all compared with state-of-the-art baselines on several real-world datasets.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Martin Ester
Department: 
Applied Sciences: School of Computing Science
Thesis type: 
(Thesis) Ph.D.

The Sultan-Caliph and the Heroes of Liberty: Heroism, revolution, and the contestation of public persona in the late Ottoman Empire, c. 1900-1918

Author: 
Date created: 
2017-06-07
Abstract: 

Drawing on a variety of Istanbul-based print media sources in Ottoman Turkish (Osmanlıca), this thesis argues that the symbolic politics of public persona played a pivotal role in certain registers of the cultural transition from Hamidian to CUP rule in the late Ottoman Empire. This process was manifested through the anthropomorphic representation of heroism and villainy, concepts that were informed by and tethered to imaginings of “ saviourhood”—i.e., whether certain figures were seen as contributing to or working against the maintenance of the health and fate of the empire in the face of foreign imperialism and separatist nationalism. Moreover, it draws on the category of heroism to demonstrate that the veneration of the ruling members of the Ottoman dynasty (Osmanlı Hanedanı or “the House of Osman”), both past and present, continued to influence forms of identification with the Ottoman state in the wake of the Ottoman revolution of 1908.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Thomas Kuehn
Department: 
Arts & Social Sciences: Department of History
Thesis type: 
(Thesis) M.A.

Channel scour on temperate alluvial fans in British Columbia

Date created: 
2017-06-01
Abstract: 

This thesis examined the morphometric controls on channel scour depth on temperate fans in British Columbia, Canada. Scour measurements and morphometric variables were catalogued for 116 fans and used to develop a predictive multivariate equation. Stepwise regression and multimodel inference were used to rank the importance of each morphometric variable and to develop the final predictive models. Watershed area, fan gradient, and fan relief were identified as the most important variables that contributed to channel scour. The predicted scour values explained approximately half of the variance in the observed scour measurements, with the largest deviations observed at higher values. A case study of a debris flow event at Neff Creek demonstrated that intense fan scour can amplify the final deposit volume and cause significant damage on the distal fan. The results of this study can be used to prioritize scour hazard assessments for infrastructure development on fans.

Document type: 
Thesis
Senior supervisor: 
Brent Ward
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) M.Sc.

The magnetic sense of honey bees - analyses of underlying mechanisms and potential function

Author: 
Date created: 
2017-11-10
Abstract: 

I studied a potential function and underlying mechanism(s) of the magnetic sense in honey bees, Apis mellifera. A waggle-dancing bee informs hive mates about a food source. Directional information pointing to the food source relative to the sun's azimuth is encoded in the angle between the straight segment of her waggle dance and a reference line such as gravity or the local geomagnetic field (LGMF). Neither cancelling the LGMF nor shifting its declination affected the recruitment success of waggle-dancing bees, implicating gravity as the reference line for the dance alignment. To study the underlying mechanism(s) of the bees’ magnetic sense, I analyzed lyophilized and pelletized bee tagmata by a Superconducting Quantum Interference Device. A distinct hysteresis loop for the abdomen but not for the thorax or the head of bees indicated the presence of magnetite in the abdomen. Magnetic remanence of abdomen pellets produced from bees that I did, or did not, expose to an NdFeB magnet while alive differed, indicating that magnet-exposure altered the magnetization of this magnetite in live bees. Following exposure of live bees to the same magnet, magnetized bees, unlike sham-treated control bees, failed to sense the presence of a magnetic anomaly, demonstrating a functional connection between magnetite in the abdomen and the magnetoreceptor, and temporary or permanent disablement of the receptor through magnet-exposure. To test whether bees sense the polarity of a magnetic field, I trained bees to associate a magnetic anomaly with a sugar water reward. I then presented trained bees with a sugar water reward in two separate watch glasses, placing one reward in the center of the anomaly that I either kept the same as during bee training (control experiment) or that I altered by reversing its polarity (treatment experiment). That bees continued to recognize the magnetic anomaly when its polarity was kept unaltered, but failed to recognize it when its polarity was reversed, indicates that bees have a polarity-sensitive magnetoreceptor. To increase the detectability of magnetite in bee tissues, I lyophilized samples to reduce water content, maximized the signal amplitude by pelletizing samples, and accounted for sample dimensions in data analyses.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Gerhard Gries
Michael Hayden
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) Ph.D.

Parenthood, childhood and organized youth sport in rural and small-town British Columbia: An ethnographic study

Date created: 
2017-10-27
Abstract: 

This thesis explores how parenthood and childhood are enacted within the context of organized youth sport in one rural and small-town British Columbian region. Studies of organized youth sport, childhood, and parenthood have primarily emphasized the experiences of (sub)urban dwellers. This has resulted in a dearth of knowledge on the spatialized processes which inform experiences of organized youth sport in rural and small towns. This ethnographic exploratory study was conducted between 2012 and 2015 in the British Columbian rural and small-town region of the West Kootenays. It draws on fieldnotes, open-ended interviews, and participant observation to capture the lived experiences of over a hundred young people, parents, and sport administrators. By utilizing a place-based, life course perspective, this study reveals the historical, structural, and spatial fluidity of concepts such as parenthood, childhood, and organized sport. A central finding in this study is that while principles of modern parenting and childhood are now part of the dominant cultural narrative, children and parents enact this narrative in conflicting and nuanced ways. Four spatialized patterns of child-rearing vis-à-vis sport emerged: (1) pursuing the dream of sporting success, (2) making organized youth sport work, (3) opting out of organized youth sport, and (4) being pushed out of organized youth sport. Parents’ and children’s relationship to place, access to resources, and commitment to varying narratives and discourses on childhood and parenthood were found to drive child-rearing practices. Overall, this study showcases the agency of rural residents and draws attention to the futility of representing rural people as solely “passive recipients” of hegemonic culture. It also draws attention to the importance of including young people alongside adults in research about their lives. Finally, this study encourages government policy-makers and community-level stakeholders in organized youth sport to take a place-based approach to the delivery of programs.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Barbara Mitchell
Department: 
Arts & Social Sciences: Department of Sociology and Anthropology
Thesis type: 
(Thesis) Ph.D.

Tobacco industry targeting of youth in Nigeria since the 1990s: An analysis of tobacco industry documents

Author: 
Date created: 
2017-10-19
Abstract: 

This study analyses the tactics and strategies used by transnational tobacco companies (TTCs) to target youth in Nigeria since the 1990s. Nigeria is considered by the tobacco industry to be a major emerging market given its population, demographic profile, and growing wealth. The study systematically searched the Truth Tobacco Industry Documents Library, available primary and secondary sources on industry activities in Nigeria, and conducted key informant interviews. It applied the theory of triadic influence as a heuristic framework to analyse the collected data. The findings suggest that TTCs have actively targeted youth in Nigeria, seeking to change behaviour through the biological/personality, and environmental/cultural and social streams. This has taken place against a backdrop of weak tobacco control policy despite Nigeria’s adoption of the Framework Convention on Tobacco Control. The study makes recommendations to strengthening youth protections under the National Tobacco Control Bill adopted into law in 2015.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Kelley Lee
Department: 
Health Sciences: Faculty of Health Sciences
Thesis type: 
(Thesis) M.Sc.

Query processing of schema design problems for data-driven renormalization

Author: 
Date created: 
2017-10-16
Abstract: 

In the past decades, more and more information has been stored or delivered in non-relational data models—either in NoSQL databases or via a Software as a Service (SaaS) application. Users often want to load these data sets into a BI application or a relational database for further analysis. The data-driven renormalization framework is often used to transform non-relational data into relational data. In this thesis, we explore how to help users to make design decisions in such a framework. We formally define two kinds of queries—the point query and the stable interval query—to help users making design decisions. We propose two index structures, which can represent a list of FDs concisely but also process the queries efficiently. We conduct experiments on two real datasets and show that our algorithms greatly outperform the baseline method when processing a large set of FDs.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Jian Pei
Department: 
Applied Sciences: School of Computing Science
Thesis type: 
(Thesis) M.Sc.

List homomorphism to irreflexive oriented trees

Author: 
Date created: 
2017-10-17
Abstract: 

Min ordering of a digraph $H$ plays an important role in deciding the existence of a list homomorphism to $H$. For reflexive oriented trees $T$, there exists a concrete forbidden induced subgraph characterization to have a min ordering. For irreflexive oriented trees $T$, the existence of a min-ordering turned out to be somewhat harder, as there are many types of obstructions to its existence. In this thesis, we first review the existing results for list homomorphism problems $LHOM(H)$ for digraphs and graphs. Second, for a specific subclass of irreflexive oriented trees, we present a concrete forbidden induced subgraph characterization to have a min ordering and to have an obstruction called invertible pair ($I$-$pair$) and digraph asteroidal triple ($DAT$). Moreover, for this subclass of irreflexive oriented trees $T$, we show that if $T$ contains one of the forbidden obstructions, then the problem $LHOM(T)$ is $NP$-complete, and is polynomial otherwise. Third, we discuss general trees, and present some approaches to find the minimal forbidden obstructions in the general case.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Pavol Hell
Department: 
Applied Sciences: School of Computing Science
Thesis type: 
(Thesis) M.Sc.

Use of hyperspectral remote sensing to examine immature blow fly development

Author: 
Date created: 
2017-11-01
Abstract: 

Medico-legal entomology, the study and application of insect science to criminal investigations, is most notably used to estimate a minimum post-mortem interval (minPMI). Examining blow fly development to make this estimation provides the minimum time it takes to reach the oldest stage associated with the remains. Unfortunately, providing the time it takes to reach a stage may underestimate the age of the insects during the lengthier post feeding stage and intra-puparial period. Hyperspectral remote sensing is introduced as a means to solve this issue and to examine the potential for narrowing these lengthier stages into days within the stages. Hyperspectral remote sensing involves sensing, recording and processing reflected and emitted energy to produce point source measurements. Spectral measurements of both immature Protophormia terraenovae and Lucilia sericata were completed from second instar to adult emergence from the mid-section, anterior and posterior ends of developing immature blow flies. Functional regressions and coefficient functions were examined for model prediction and generalization to identify demarcations within stadia to age the immature blow flies. Aging P. terraenovae larvae was successful at wavelengths ranging from 400-1000nm, however, at that wavelength range, only the last day of the intra-puparial period could be distinguished from the first five days. Immature Lucilia sericata were examined at a wider range of wavelengths (350-2500nm) and model prediction and generalization for both pupae and larvae was possible. Similarities and differences were found between species and potential contributing factors were considered such as range of wavelengths analyzed, food substrate, significance of washing away surface contaminants before measuring, contributions of cuticular hydrocarbons, and potential surface bacteria, best region to measure the immature blow fly and replication experiments. Hyperspectral remote sensing not only allows an entomologist to incorporate more precision in their estimate but error rates are also introduced which is required of a forensic science according to the National Academy of Sciences.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Gail Anderson
Department: 
Arts & Social Sciences: School of Criminology
Thesis type: 
(Thesis) Ph.D.