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.

The relationship between fracture morphology and bone biomechanics: A study of changes occurring in juvenile porcine ribs over the early postmortem interval

Date created: 
2020-03-06
Abstract: 

Forensic anthropologists are often faced with the challenge of determining fracture timing based on bone features, usually discussing it in terms of a “fresh” versus “dry” bone response. Yet it is still unclear how long into the postmortem period bone can retain its fresh characteristics, particularly juvenile rib bone. Juvenile porcine ribs were used to examine 1) changes in the biomechanical properties of bone in response to localized load, and 2) changes in the morphology of the resulting fractures over the early postmortem interval (PMI). Two macroenvironments (subaerial and burial) were recreated in a greenhouse. Samples were placed on the surface of soil filled containers and distinct samples were buried in the same containers, with a total of 16 containers being studied over 12 months. Samples were collected weekly for the first 4 weeks, the subsequent two were collected 2-weeks apart, and the remaining 4-weeks apart. Individual ribs 8-11 were selected from the subaerial (n=146) and the burial (n=134) environments and fractured experimentally. Six biomechanical parameters were collected from each test and median values were obtained for each sample. Each fracture was then examined for eight morphology characteristics and frequencies were calculated for each sample. In the subaerial samples, multiple regression analysis showed that displacement at peak force, displacement at failure and failure stiffness were significantly associated with the PMI. Type of fracture, presence of plastic deformation and presence of cortical peeling were also significantly associated with the PMI. In the buried samples, multiple regression analysis showed no significant association between bone biomechanics and the PMI, and only a moderate association was found between the PMI and fracture morphology, specifically in the type of fracture, fracture surface and presence fiber pull-out. Although a transition from “fresh” to “drier” bone was apparent in the subaerial samples, a persistence of typical “fresh” bone response over the year-long PMI was evident in the buried environment. Accurate timing assessment of juvenile rib fractures is thus likely to be compromised from the analysis of bone features alone and further investigations are necessary for more confident and accurate rib trauma analysis, specifically when involving child remains.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Hugo Cardoso
Department: 
Environment: Department of Archaeology
Thesis type: 
(Thesis) Ph.D.

Ecological consequences of flow regulation by Run-of-River hydropower on salmonids

Author: 
Date created: 
2020-04-02
Abstract: 

Streams are dynamic, disturbance-driven ecosystems, where flow plays a dominant role structuring biological communities. Anthropogenic activities on streams change natural patterns of flow and disturbance, which in turn alters the conditions to which resident fishes are adapted, and their survival and fitness. Run-of-river (RoR) hydropower projects are an example of an anthropogenic activity that may alter stream ecosystems by temporarily diverting a proportion of stream flow to produce electricity. RoR hydropower projects have increased considerably in number and importance in the last three decades in both British Columbia and worldwide. Although there is a perception that RoR hydropower has minimal effects on stream ecosystems due to the small physical footprint of projects, we know surprisingly little about the impacts of RoR hydropower on fish populations. In this thesis, I use a combination of published research, empirical data, and models to evaluate a range of hypotheses regarding how RoR hydropower may affect fish populations, concentrating on salmonid species whose freshwater habitats often overlap with RoR projects. In Chapter 2, I synthesize the impact pathways by which RoR hydropower may influence salmonid populations, inferred from studies of reservoir-storage hydropower and salmonid ecology. In Chapter 3, I use empirical data to quantify increases in water temperature due to RoR flow diversion and explore the possible consequences for resident fish growth with bioenergetics models. In Chapter 4, I evaluate how stranding from anthropogenic flow fluctuations affects the long-term population dynamics of coho salmon (Oncorhynchus kisutch) in RoR-regulated rivers using a matrix model integrating both the strength and timing of freshwater density dependence. Finally, in Chapter 5, I quantify the high level of uncertainty in how much compensation habitat is required to offset chronic mortality incurred by multiple life-stages of coho salmon. The global emergence of RoR hydropower projects emphasizes the importance of understanding their effects on aquatic ecosystems. Overall, our capacity to protect and restore threatened salmonid populations rests upon our ability to not only better understand the pathways of impacts, but also the effectiveness of both natural (density dependence) and human (habitat compensation) interventions that can be used to offset anthropogenic mortality.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Wendy J. Palen
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) Ph.D.

3D convolutional neural networks for Alzheimer’s disease classification

Author: 
Date created: 
2020-01-21
Abstract: 

Dementia of the Alzheimer’s type (DAT) is a neurodegenerative disease characterized by abnormal brain metabolism and structural brain atrophy. These functional and structural changes can be observed in images acquired using 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) and structural magnetic resonance imaging (MRI). Traditional machine learning framework for DAT classification often involves time-consuming segmentation of brain images as part of the feature extraction process, while deep neural networks can learn DAT-related patterns directly from brain images to generate DAT probability scores. In this thesis, we design 3D convolutional neural networks (CNN) for two applications: classification and segmentation. We design classification networks for single modality use and perform comprehensive evaluation by measuring the performance of our networks on images along the entire DAT spectrum. To support traditional DAT classification framework, we design a fast and accurate segmentation pipeline. We propose a hemisphere-based approach where we train networks to localize and segment hemispheres.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Faisal Beg
Department: 
Applied Sciences: School of Engineering Science
Thesis type: 
(Thesis) M.A.Sc.

Approximate marginal likelihoods for shrinkage parameter estimation in penalized logistic regression analysis of case-control data

Author: 
Date created: 
2020-04-17
Abstract: 

Inference of associations between disease status and rare exposures is complicated by the finite-sample bias of the maximum likelihood estimator for logistic regression. Penalised likelihood methods are useful for reducing such bias. In this project, we studied penalisation by a family of log-F priors indexed by a shrinkage parameter m. We propose a method for estimating m based on an approximate marginal likelihood obtained by Laplace approximation. Derivatives of the approximate marginal likelihood for m are challenging to compute, and so we explore several derivative-free optimization approaches to obtaining the maximum marginal likelihood estimate. We conduct a simulation study to evaluate the performance of our method under a variety of data-generating scenarios, and applied the method to real data from a genetic association study of Alzheimer's disease.

Document type: 
Graduating extended essay / Research project
File(s): 
Senior supervisor: 
Brad McNeney
Department: 
Science: Department of Statistics and Actuarial Science
Thesis type: 
(Project) M.Sc.

Human gait monitoring using wearable fabric-based strain sensors and deep supervised learning

Author: 
Date created: 
2019-12-05
Abstract: 

Continuous lower body monitoring is an important step for real-time feedback training of runners and in-home rehabilitation assessment. Optical motion capture systems are the gold standards for gait analysis, but they are spatially limited to laboratories. Recently, wearable sensors have gained attention as unobtrusive methods to analyze gait metrics and health conditions. In this study, a wearable system capable of estimating lower body joint angles in sagittal, frontal, and transverse planes during gait was developed. A prototype with fiber strain sensors was fabricated. The positions of the sensors on the pelvis were optimized using a genetic algorithm. A cohort of ten people completed 15 minutes of running at 5 different speeds for gait analysis by our prototype device. The joint angles were estimated by a deep convolutional neural network in inter- and intra-participant scenarios. In intra-participant tests, root mean squared error (RMSE) and normalized root mean squared error (NRMSE) of less than 2.2° and 5.3 %, respectively, were obtained for hip, knee, and ankle joints in sagittal, frontal, and transverse planes. The RMSE and NRMSE in inter-participant tests were less than 6.4° and 10%, respectively, in the sagittal plane. The accuracy of this device and methodology could yield potential applications as a soft wearable device for gait monitoring.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Carlo Menon
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Learning shape-to-shape transformation

Author: 
Date created: 
2020-05-14
Abstract: 

Many problems in computer graphics and geometric modeling, e.g., skeletonization, surface completion, and shape style transfer, can be posed as a problem of shape-to-shape transformation. In this thesis, we are interested in learning general-purpose shape transform, e.g., between 3D objects and their skeletons, between chairs and tables, and between letters of two different font styles, etc. With a point-based shape representation, we explore the problem of learning general-purpose shape-to-shape transformation, under two different settings: i). having shape-level supervision, ii). unsupervised. We present P2P-NET, a deep neural network, for learning shape transform under shape-level supervision. It is trained on paired shapes from the source and target domains, but without relying on point-to-point correspondences between the source and target point sets(i.e., point-level supervision). The architecture of the P2P-NET is that of a bi-directional point displacement network, which transforms a source point set to a prediction of the target point set with the same cardinality, and vice versa, by applying point-wise displacement vectors learned from data. For an unsupervised setting, we introduce LOGAN, a deep neural network aimed at learning general-purpose shape transforms from unpaired shape domains. It consists of an autoencoder to encode shapes from the two input domains into a common latent space, where the latent codes are overcomplete representations for shapes. The translator is based on a generative adversarial network (GAN), operating in the latent space, where an adversarial loss enforces cross-domain translation while a feature preservation loss ensures that the right shape features are preserved for a natural shape transform. We conduct ablation studies to validate each of our key designs and demonstrate superior capabilities in shape transforms on a variety of examples over baselines and state-of-the-art approaches. Several different applications enabled by our general-purpose shape transform solutions are presented to highlight the effectiveness, versatility, and potential of our networks in solving a variety of shape-to-shape transformation problems.

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

Decolonizing municipal heritage programs: A case study of the city of Victoria’s heritage program

Author: 
Date created: 
2020-04-15
Abstract: 

This research examines the City of Victoria’s heritage program, which comprises of civic plans, policies and associated agencies, to understand whether or not it can meet the Truth and Reconciliation Commission of Canada: Calls to Action. I have argued that the City of Victoria’s heritage program must be adapted to include intangible cultural heritage to support decolonization and the representation of Indigenous cultural heritage. Intangible cultural heritage offers an accessible way for the field of municipal heritage planning to become more inclusive and supportive to reconciliation.

Document type: 
Graduating extended essay / Research project
File(s): 
Senior supervisor: 
Meg Holden
Department: 
Arts & Social Sciences: Urban Studies Program
Thesis type: 
(Project) M.Urb.

Access, equity, and ethics: A qualitative exploration of Rwanda’s maternal community health worker program

Date created: 
2020-04-28
Abstract: 

Improving maternal health outcomes is one of the main health concerns in Rwanda, a country that was shaken by the 1994 genocide against the Tutsi. As part of the rebuilding process, the health sector focused on using community participation to promote access to maternal healthcare. One such initiative was the creation of the maternal community health worker role as part of the community health worker program. Maternal community health workers are volunteer women elected by their communities to provide basic maternal health services while encouraging the utilization of formal healthcare services for antenatal care, delivery, and postpartum care. Using a qualitative case study approach, my dissertation research explores some of the facilitators and barriers to access to the community-based services offered by maternal health community health workers. I draw on the findings from in-depth interviews with maternal community health workers and women who have used their services in five Rwandan districts to pursue three distinct, yet related, analyses. First, I highlight the different aspects of access to maternal health care at the community level in Rwanda: availability, accessibility, affordability, acceptability, and accommodation. Second, I identify specific strategies employed by these volunteer health workers to facilitate equitable access to maternal health services while operating in a low resource setting. Third, through the lens of an ethics of care framework, I examine why women decide to become maternal community health workers and how they are selected in their communities to take on this responsibility. Overall, this research suggests that community participation is valuable for promoting maternal health outcomes but raises health equity concerns for the nature of the maternal community health worker role. Such concerns shape the program’s sustainability and may impact the overall efforts to enhance positive maternal health outcomes in Rwanda. Further research is needed to explore other aspects of community participation in maternal health, such as the involvement of local leaders who work closely with maternal community health workers to enhance the success of this program.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Valorie Crooks
Department: 
Environment: Department of Geography
Thesis type: 
(Thesis) Ph.D.

Building labour force resilience in British Columbia

Author: 
Date created: 
2020-04-16
Abstract: 

With the rapid growth of automation and technological advancement, the skills and competencies required across British Columbia’s economic development regions are evolving. As the province shifts towards a more digital, knowledge-based economy, it is important to consider the development of BC’s labour force. While there are a number of initiatives targeting the next generation of workers, few supports sufficiently address the needs of mid-career workers in medium-skill occupations, who are more likely to experience challenges in adapting to changing job requirements. The purpose of this study is to determine the role the provincial government can play in building labour market resilience among this group. Using a case-study analysis as the primary research methodology, this study evaluates public employment supports in Ontario, Québec and Australia to identify policy options that may aid in streamlining job-transitions in BC.

Document type: 
Graduating extended essay / Research project
File(s): 
Senior supervisor: 
Nancy Olewiler
Department: 
Arts & Social Sciences: School of Public Policy
Thesis type: 
(Project) M.P.P.

Experiences of Latin Americans seeking professional jobs in Greater Vancouver

Author: 
Date created: 
2020-03-05
Abstract: 

Canada is often acknowledged as one of the most welcoming countries for immigrants around the world. However, literature reveals that Canadian skilled immigrants, particularly those from Latin America, are often unemployed, underemployed, and earn significantly less than their Canadian-born counterparts. This dissertation examines the experiences of Latin American Skilled Immigrants (LSIs) in Metro Vancouver, including: the factors that prompt them to migrate; their experiences with the Canadian immigration system; and their transition into the new social space. I critically deconstruct dominant economic approaches to immigration and challenge human capital explanations of the phenomena. By utilizing a multiple case study research design, I conducted in-depth interviews with nine LSIs and coauthored their narratives. Filtered through the lenses of Bourdieu's theory of social reproduction, Rizvi’s ideas regarding the neoliberal imaginary, and Bauman’s concepts of the stranger’s aporia, I found that migration appears as a strategy of social reproduction in which participants aim to maintain or enhance their position in the social space. Furthermore, the neoliberal imaginary in conjunction with the participants’ habitus largely shaped their perception of what moving in the social space looks like and how it is achieved. With respect to their transition into Canada, I found that participants who entered with prearranged jobs (WPJ) had more positive experiences settling and adapting than those who entered without prearranged jobs (WOPJ). Participants WOPJ faced more onerous immigration processes and upon arrival, they encountered a contradictory society that intensely seeks to select the best and brightest, but does little to facilitate their integration and in some cases is even obstructive and discriminatory. Through the same theoretical framework, I realized that settling into the community and transitioning into the labour market did not solely depend on the participants’ intrinsic human capital, but also on a complex series of internal contradictions and relations of power created by the neoliberal imaginary. Acknowledging this complexity may lead to a more comprehensive and unprejudiced construction of the Canadian immigration system. This would allow more room to discuss and address the ethical and moral challenges that many immigration stakeholders face, particularly the higher education system in the era of academic neoliberalism.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Kumari Beck
Department: 
Education: Faculty of Education
Thesis type: 
(Thesis) Ed.D.