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.

Analysis of 2:1 Internal Resonance in MEMS Applications

Author: 
Date created: 
2018-01-12
Abstract: 

Micromachined resonators are typically used within their linear range of operation. Recently, there has been an increasing interest in understanding nonlinearities and potentially employing them to improve the performance of resonance-based devices. The focus of this thesis is to study the nonlinear mode coupling at 2:1 internal resonance both experimentally and analytically. It is shown that quadratic nonlinearities can couple two vibrational modes of a micro-resonator with a 2:1 ratio between two of its mode frequencies. This nonlinear coupling of modes can lead to the transfer of energy between these two modes through internal resonance. To study the phenomenon, a modified T-beam structure is proposed, and a simplified mathematical model of operation including the nonlinearities is developed for this system. Perturbation solutions of the mathematical model, along with finite element and reduced-order method analysis are used to describe the nonlinear behaviour of the system. Experiments are performed on a modified micro T-beam structure with 2:1 ratio between its resonance frequencies. Nonlinear modal interactions between vibrational modes, jump and saturation phenomena, and bandwidth enhancement are also observed both in experiments and numerical simulations. The effect of damping on the behaviour of the system is also studied. Some of the potential applications of internal resonance in sensing are also proposed and discussed throughout the thesis.

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

Voluntary Driven, Velocity Controlled Tremor Suppression

Author: 
Date created: 
2017-12-15
Abstract: 

The standard course of treatment for pathological tremor mainly involvespharmacotherapy. However, treatment can be challenging as individual responses totherapy vary widely. Individuals with a disabling or medication refractory tremor, mayhave the option for one of several surgical procedures. Essential Tremor (ET) andParkinson’s Disease (PD) are considered to be among the most pervasive of tremorrelated disorders. Overall pathological tremor prevalence statistics range from 2% to wellover 10% in the elderly. Up to 60% of those affected by tremor experience disability intheir Activities of Daily Living (ADL) and more than a quarter struggle to find reliefthrough conventional treatments. There is, therefore, a persuasive case for alternativetherapies for individuals with pathological tremor. This thesis proposes a tremorsuppression approach to track the intentional motion. Typically tremor suppressionmethods estimate the tremor component and produce a counteracting signal. Thesuggested approach instead predicts the voluntary motion component via forceinformation, while the tremor signal is regarded as a motion disturbance andconsequently rejected. The approach is demonstrated in a modular form for flexibility inimplementation. The suppression approach, involving an admittance and speedcontrolled feedbacks, was evaluated experimentally with a benchtop tremor simulationsystem. Parametric stability and controller tuning were demonstrated, and response timeperformance specifications were achieved. Spectral analysis results show a 99.8%tremor power reduction; the power reduction related to the voluntary movement wasinstead negligible (0.18%). A robotic orthosis was subsequently developed to validatethe approach for the suppression of pathologic elbow tremor. Two types of roboticallysimulated human inputs were evaluated in addition to employing orthosis gravitycompensation. Finally, nine participants with either ET or PD were recruited andperformed computerized pursuit tracking tasks with the orthosis. The mean tremor powerreduction was 94.4%; significantly higher than typically achieved with pharmacotherapy.Importantly, the effect to the voluntary motion was limited to only 6.6%. Whenmechanically suppressing tremor, there is a risk of preventing the individual with tremorfrom performing volitional movements. An important contribution of this work involves theexplicit treatment of the impact to the volitional motion.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Carlo Menon
Department: 
Applied Sciences: School of Engineering Science
Thesis type: 
(Thesis) Ph.D.

Methods for chemical mapping of O-GlcNAc in the Drosophila genome

Author: 
Date created: 
2017-07-10
Abstract: 

O-linked N-acetylglucosamine (O-GlcNAc) is an important protein modification installed onto hundreds of nucleocytoplasmic proteins by O-GlcNAc transferase (OGT). Here, I discuss the development of an antibody-free metabolic feeding approach, which enables unbiased mapping of O-GlcNAcylated proteins in a genome-wide manner. This mapping method is detailed in Drosophila and compared to other O-GlcNAc mapping methods related to chromatin immunoprecipitation followed by sequencing (ChIP-seq), in order to demonstrate its overall efficacy. Using a combination of experimental and bioinformatics methods, I define new genes regulated by OGT. I also report on the development of robust software used to process and analyse time course ChIP-seq data, and prove its versatility and proficiency using both simulated and published data sets. This software is then applied to the analysis of a time course O-GlcNAc chemical mapping experiment in Drosophila larvae, generating the first ever time course ChIP-seq experiment performed on both a protein modification and in a living organism. Using this approach I am able to distinguish between loci that are more sensitive to O-GlcNAc cycling and those that are affected more by protein turnover. These studies provide an improved understanding of the regulation of gene expression by O-GlcNAc, while providing the wider community with new computational tools for time resolved analysis of genome-wide binding by proteins.

Document type: 
Thesis
File(s): 
Senior supervisor: 
David Vocadlo
Department: 
Science: Department of Molecular Biology and Biochemistry
Thesis type: 
(Thesis) M.Sc.

Community engagement through the lens of intersectionality

Author: 
Date created: 
2018-04-20
Abstract: 

Despite the growing interest in community engagement as an alternative way of building evidence in public health and its potential to address health disparities in marginalized populations, there is a dearth of knowledge and evidence of the ways in which participatory approaches, such as community-based participatory research (CBPR), engage and impact people with lived experience of mental illness. Although CBPR offers the promise of addressing factors associated with mental health inequity, it faces its own set of ethical and methodological concerns related to the authenticity of community participation and a lack of understanding of the ways in which active engagement in CBPR affects community members. For people with psychiatric diagnoses, mental health inequities are a reflection of persistent and intertwined social and structural inequities rooted in historical exploitation and ongoing systemic subjugation through psychiatrization, criminalization and stigmatization of mental distress. While people with lived experience of mental illness face similar mental health inequities, the way they experience or respond to oppression is contingent on the ways it intersects with different social locations, such as gender, social status or race and power relations, such as sanism. Thus, an exploration of engagement from the participants’ perspective and a critical examination of multiple and intersecting social factors and underlying power relations are needed. In this Master’s thesis, I apply a critical lens of intersectionality to a CBPR case study (Imagining Inclusion) to examine the research question: “How do the intersections of social locations and systemic and structural processes shape the experience of engagement in CBPR for people living with mental illness?” Intersectionality-informed analysis of thirteen in-depth individual interviews with people living with a mental illness revealed three major themes: 1) definitions and dimensions of community engagement; 2) tensions around joining Imagining Inclusion and sustaining engagement; and 3) tensions around collaborative relationships. In this project, I contribute to the call for this type of consideration of engagement by employing an intersectionality lens to explore the term engagement and the experiences of engagement in Imagining Inclusion from the perspectives of people with lived experience of mental illness.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Dr. Marina Morrow
Department: 
Health Sciences: Faculty of Health Sciences
Thesis type: 
(Thesis) M.Sc.

The international health landscape of Cozumel Island, Mexico

Author: 
Date created: 
2018-02-09
Abstract: 

Cozumel Island is the largest of Mexico’s eastern islands. It is the Western Caribbean’s most popular cruise destination, and is well-known for its crystalline waters and mosaic reefs that attract dive enthusiasts from around the globe. Joining the millions of international tourists that set foot upon the island each year, Cozumel is also home to a significant community of lifestyle and retirement migrants. Recognising this conglomeration of global bodies, and that some will inevitably require medical assistance, this dissertation presents an exploratory case study of Cozumel Island’s health landscape as an international phenomenon. It is driven by three primary objectives that seek to unpack the aesthetic nature of Cozumel Island’s international care settings, determine the intersecting mobilities at play within the island’s international health landscape, and understand both the provision and reception of care for international patients on Cozumel Island. Analysing field experiences, photographs, and semi-structed interviews with international lifestyle and retirement migrants, as well as health care providers working within the island’s private hospitals and medical clinics, three discrete analyses provide insight into Cozumel Island’s international health landscape. First, the aesthetics of pharmaceutical signage are explored and unpacked within the sociolinguistic framework of the linguistic landscape to consider how tourists visiting Cozumel Island might interpret such markers of medicinal merchandise, revealing imagery that positions pharmaceuticals as both souvenirs and suggestions of personal health autonomy. Second, international lifestyle and retirement migrants’ perceptions and beliefs about Cozumel’s pharmacy sector are analysed, revealing a number of concerns that exist in relation to participants’ spatial mobilities. Finally, health care workers’ experiences of treating international tourists are unpacked and found to entail multiple challenges that can preclude effective and safe treatment. When taken together, and as products of this dissertation’s objectives, these analyses situate Cozumel Island’s international health landscape as component within a complex archipelago of tourism, health and other mobilities, that produce it as connected, dynamic, and a continuously emergent setting of transnational health processes.

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

Spatial Narratives of Property Loss: Social memory and the dispossession of Japanese Canadian-owned property in British Columbia

Author: 
Date created: 
2018-01-25
Abstract: 

This project informs an emergent literature on memory and property. More specifically, it uses a geographical perspective to analyze memories of property loss. The case study – a sample of thirty-one oral histories related to the dispossession of Japanese-Canadian-owned property during the 1940s – comes from the Landscapes of Injustice (LoI) SSHRC-funded project. LoI addresses haunting across the social memory of Canada; by sharing spatially-grounded life stories, interview participants unsettle under-recognized meaning attached to property loss. To embrace the centrality of space and place to this reckoning, I frame these “spatial narratives” around the processes of hauntology in les lieux de mémoire (sites of memory) (Derrida, 1994 & Nora, 1989). I focus on three distinct themes across the narratives and to analyze them, draw from the work of three contemporary property theorists. Citizenship explores the political undertones of “Canadian” property ownership and loss (Singer, 2000); Investment identifies the monetary and non-monetary values put into property (Becher, 2014); and Belonging details important networks that structure property and create unique experiences of belonging (Keenan, 2015). As I recognize the complex nature of social memory, I also illustrate the ways in which these themes interconnect. Finally, I argue that spatial narratives from LoI gesture at a deeper and wider story of property; at the intersection of social memory and property, there is a window into the layered history of remembering and forgetting dispossession in colonized British Columbia.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Nicholas Blomley
Department: 
Environment: Department of Geography
Thesis type: 
(Thesis) M.A.

Microfauna at Tse’K’wa: Paleoenvironmental reconstruction in the Peace River Region, Northeast British Columbia

Date created: 
2017-12-07
Abstract: 

The transition from the late Pleistocene to the early Holocene is known to have been a time of dramatic climatic and environmental changes, however there is still much that is not known about this period in North America. The Peace River Region of Northeast British Columbia is especially interesting because it is located in the hypothesized biogeographic corridor, allowing previously uninhabitable land to become open for colonization by plants, animals and humans at the end of the last ice age. Tse’K’wa (formerly known as Charlie Lake Cave), is a unique site within the Peace River Region that has well preserved fauna, well stratified and dated layers, and spans the late Pleistocene/early Holocene transition. This study uses the Tse’K’wa microfauna to understand local and regional environmental change, and its implications for human occupation in Northeast British Columbia. This study examines vertebrates deposited at Tse’K’wa between about 10,500 and 9,000 BC. A sequence of four assemblages documents a change from open to forested habitats, as well as the development of local wetlands. The nature and timing of these faunal changes correlates well with palynological studies.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Jon Driver
Department: 
Environment: Department of Archaeology
Thesis type: 
(Thesis) M.A.

Youth Activism and the Black Freedom Struggle in Lawnside, New Jersey

Date created: 
2018-01-12
Abstract: 

This thesis is an examination of youth activism during the black freedom struggle in Lawnside, New Jersey; one of ten self-governing African American communities in the United States. A critical factor in Lawnside’s narrative is that its young people both historically and today do not experience integration until the high school level where they are a distinct minority of the student body in a white community’s high school. During the civil rights/black power era, Lawnside’s young people created their own activist organization called the Young Blacks of Lawnside that pursued an agenda of non-violence, community improvement, educational advancement, and peaceful activism. Many African American youth from Lawnside were also inspired to address inequality and African American educational and cultural concerns at their high school by engaging in acts of collective violence and non-violent direct action. In these protest efforts, which included a boycott, two sit-ins, and a protest march, female students often held positions of influence and leadership and students acted with little direction or interference from parent groups or African American civic leaders.

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

Appealing to the masses: The allure of social media

Date created: 
2018-01-26
Abstract: 

Social Media is one of the most prevalent forms of communication in today’s society. However, research has consistently noted that there are risks associated with the use of social media. The current study looks to understand what makes social media appealing to users that they forego or limit their privacy and security online. Consistent with previous research, the current study found that users considered both self-disclosure and self-exhibition as appealing characteristics of social media. Users want to both look at other users and expose themselves to other users. However, the findings indicated that the way users treat social media depends on their awareness and cognition of the risks of social media use. Users utilized the platforms to limit the information dispersed about them, but were not as limiting with service providers. The findings also indicated that users lacked knowledge or understanding of what "personal identifiable data" entails, to the detriment of their online privacy.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Richard Frank
Department: 
Arts & Social Sciences: School of Criminology
Thesis type: 
(Thesis) M.A.

Regulation and conservation of caspase-activated autophagy

Date created: 
2017-06-27
Abstract: 

Autophagy is an evolutionarily conserved cellular process that recycles proteins and organelles to maintain cellular homeostasis or provide an alternative source of energy in times of stress. While autophagy promotes cell survival, it can also be regulated by proteins associated traditionally with apoptosis. In an effort to better understand the complex intersections of these disparate cell fates, previous studies in Drosophila identified an apoptotic effector caspase, Dcp-1, as a positive regulator of starvation-induced autophagy. Further, the Drosophila heat-shock protein, Hsp83, was identified as a Dcp-1 interacting protein and a putative negative regulator of autophagy. The aims of my thesis were to investigate the relationship between Dcp-1 and Hsp83 in the context of autophagy, and to determine if caspase-regulated autophagy was functionally conserved in humans. In vivo analyses of Hsp83 loss-of-function mutants in fed conditions showed increases in both autophagic flux and cell death. Hsp83 mutants also had elevated levels of pro-Dcp-1, which was attributed to reduced proteasomal activity. Analyses of an Hsp83/Dcp-1 double mutant revealed that the caspase was not required for cell death in this context but was essential for the ensuing compensatory autophagy, female fertility, and organism viability. These studies not only demonstrated unappreciated roles for Hsp83 in proteasomal activity and new forms of Dcp-1 regulation, but also identified an effector caspase as a key regulatory factor for sustaining adaptation to cell stress in vivo by inducing compensatory autophagy. To address whether effector caspases also regulate starvation-induced autophagy in human cells, caspase-3 (CASP3), a human homolog of Dcp-1, was examined in several human cell lines. These studies showed that CASP3 was required for the upregulation of starvation-induced autophagy in most cell lines examined, but was not required for maintaining basal levels of autophagy. In human cells, another heat-shock family member, HSP60, was identified as a CASP3-interacting protein. HSP60 was shown to negatively regulate autophagy by controlling the subcellular localization of CASP3 in response to nutritional status. Epistasis analyses suggest that the increase in autophagy observed from loss of HSP60 was dependent on the accumulation of cleaved CASP3 in the cytosol. This work highlights a novel function for CASP3 in starvation-induced autophagy in human cells and illustrates how its response is regulated by HSP60-controlled subcellular localization. Altogether, my studies provide novel insights into stress adaptive relationships between heat-shock proteins and caspases in Drosophila and human cells.

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