VictorJuiz/thesis huggingface dataset:
The Role of Geometric and Mechanical Properties in Bird-beak Configuration Formation in Thoracic Endovascular Aneurysm Repair

Thoracic endovascular aortic repair (TEVAR) is a minimally invasive treatment for thoracic aortic conditions including aneurysms and is associated with a number of postoperative stent graft related complications. Bird-beak configuration is a wedge-shaped gap at the proximal end of the deployed stent graft in TEVAR that leads to incomplete seal and other complications such as type Ia endoleak (failure of proximal stent graft seal). In this study it is hypothesized that the geometric and mechanical properties of aorta and stent graft contribute to bird-beak. This study proposes a novel framework for creating realistic population-based computational models of TEVAR focused on aneurysms that allow for developing various clinically relevant geometric configurations and scenarios that are not easily attainable with limited patient data. This framework is employed to conduct a sensitivity analysis on the geometric and mechanical characteristics of aorta and stent graft in relation to bird-beak formation. The most significant parameters contributing to bird-beak are identified as aortic arch angle, TEVAR landing zone, and stent graft oversizing. The computational framework is further used to investigate the impact of various stent graft design parameters on bird-beak formation through testing a number of conceptual device designs by varying several design parameters from a commercial stent graft model as the baseline for this study. A stent graft with reduced stent height and fabric gap is identified to have the most significant impact on reduction of bird-beak size. This stent graft design maintains the radial forces within an acceptable range. Furthermore, the computational models are used to simulate patient-specific TEVAR cases to verify the accuracy of the proposed framework in predicting the proximal position of deployed stent graft as well as the presence of bird-beak. The patient-specific TEVAR simulations can predict bird-beak length and angle size with less than 10 and 24% error, respectively. The findings of this study can provide insight into the surgical planning and device selection process with the goal of minimizing bird-beak formation. The proposed framework has the potential to predict bird-beak formation in TEVAR preoperatively and modify surgical plans accordingly.

Keywords: Aneurysm
Aorta
Computational simulation
Finite element method
TEVAR
Advisor: Amon, Cristina H.
Forbes, Thomas L.
A Multiplayer Target Defense Game Between Quadrotor Teams

The rapid development of unmanned aerial vehicles (UAVs) has created enormous opportunities as well as emerging security risks. As increasing drone accidents and threats have been reported, the research interest in counter-UAV missions has also grown. The goal of this thesis is to find a guidance law, or a defending strategy, in a counter-UAV mission that helps a group of defenders to reach in vicinity of a group of invading drones so the latter can be intercepted before entering a target area. For the defending strategy to be robust, a conservative assumption is adopted that the invaders are also capable of optimizing the invading strategy, instead of following a predefined path. This gives rise to a target defense differential game. Because player velocities have a fundamental impact on the solution, the problem is divided into two branches, where the defenders travel faster and slower respectively. When the defenders travel faster, capture is guaranteed, therefore the focus is on how far from the target area the invaders can be captured. The proposed defending strategy is fully distributed, containing a local subgame for each defender and a task assignment problem that allocates the invaders among the defenders. The optimality of the proposed solution is extensively discussed. When the defenders travel slower, an invader can only be captured by two cooperative defenders in most situations. In addition, the defenders must recede toward the target area in exchange for a chance of capture. The optimal defending strategy is a tradeoff between the receding distance and other assisting factors, such as the cooperation from another defender, the boundary of the game region, or the topology of the target area. These three aspects are discovered and explained in the solution of three different slower-defender games. The focus of solving a slower-defender game is the defenders' winning condition that whether the invaders can be captured outside of the target area. Two methods are proposed to design a computationally effective state-feedback defending strategy to meet these winning conditions. The proposed defending strategies are validated through experiments.

Keywords: Counter-UAV
Differential game
Dominance region
HJI equation
Optimal control
Target defense game
Advisor: Liu, Hugh HL
Decolonize and Divest: The Changing Landscape of Oil-Sponsored Museums in Canada

This dissertation investigates the relation between oil companies and museums in Canada. I situate museums in a moment of critical change, wherein Canadian museums lead global efforts to “decolonize” – or reform the ways they engage with Indigenous stakeholders and Indigenous collections – while maintaining financial partnerships with the oil industry. With activists and cultural workers increasingly calling for museums to divest from fossil fuels in Europe and the U.S., I interrogate the reality of museum practice in two oil-sponsored museums: the Glenbow Museum in Calgary and the Canadian Museum of History in Gatineau. Focusing on two museum exhibitions from different moments of Canadian history, I trace the political economic implications of industry support for cultural initiatives and highlight the granular experiences of museum professionals who work on such projects. I explore the first instance of contested oil sponsorship in a Canadian museum –The Spirit Sings: Artistic Traditions of Canada’s First Peoples (1988), sponsored by Shell – to argue that, despite community-informed reforms to collections care, exhibitions, or programming, Canada’s museum sector has neglected Indigenous groups’ early critiques of oil sponsors and their ties to land dispossession. The next case study explores the more recent Canadian History Hall (2017) – sponsored by the Canadian Association of Petroleum Producers – to illustrate the contemporary manifestations of extractive interests that emerge in the development of a large, national history exhibition. Together, the historical and contemporary data I collected through archival research, interviews, and document analysis point to the complexity of justice-oriented museology in a country deeply connected to exploitative resource extraction. I argue that while there is minimal overlap between sponsors and exhibition development, the contradictions of corporate funding highlight the ongoing hegemonic function of museums. Through reflective engagement with contributions from decolonial pedagogy and museology, I propose that undertheorized aspects of museum operations, including the behind-the-scenes practices of funding, should be similarly informed by the socially engaged frameworks currently underpinning museum work in Canada.

Keywords: decolonization
divestment
exhibitions
museums
oil
sponsorship
Advisor: Mihalache, Irina D
The Noncontractile Phage Tail-like Bacterial Killing Nanomachines – Characterizing the Specificity Determinants of the F-Pyocins of Pseudomonas aeruginosa

The rise of antibiotic-resistant bacterial strains poses an enormous threat to our collective human existence; hence, there is a dire need to search for alternatives to current antibiotic treatment options. In this work, I characterized the non-contractile phage tail-like entities called F-pyocins. F-pyocins are high molecular weight bacteriocins resembling non-contractile bacteriophage tails such as E coli phage lambda of the Siphoviridae family. They are produced by many Pseudomonas aeruginosa strains and possess bactericidal activity against other strains of the same species. Structurally, F pyocins are differentiated into the tubular portion and the tail tip complex lying at the bottom of the tail. F-pyocins produced by different strains of Pseudomonas aeruginosa, share strong sequence similarities in the genes encoding the tubular portion, however, notable variability exists in the last six genes at the tail tip complex, collectively designated here as specificity genes. In this study, I differentiated F-pyocins into groups based on the sequence diversity in their specificity genes, which assort into two modules – modules 1 and 2, each comprising three genes. I showed that swapping module 2 from one F-pyocin to the other changes the killing spectrum of the chimeric F-pyocin to new P. aeruginosa strains. This is mediated by the interaction of the module 2 c-terminus with the LPS O-specific antigen (OSA) of the target P. aeruginosa strain. Module 1 on the other hand was shown to interact with target receptor moieties deeper within the LPS core implying that each module has selective specificity and that F-pyocins may have evolutionarily co-opted both modules to ensure the successful killing of their target P. aeruginosa strain. The plasticity of F-pyocins was further explored by engineering them with side fibre proteins from siphophage DMS3, which retargeted their bactericidal spectrum. Summing all my findings, I concluded by proposing the mechanism with which F-pyocins bind and kill susceptible P. aeruginosa strains. This study provides valuable insight into the specificity determinants of F-pyocins and how they interact with the bacterial surface, which further helps us to understand how they can be explored as potential alternatives to antibiotics.

Keywords: Bacteriocin
F-pyocin
LPS
Phage
Pseudomonas aeruginosa
Specificity genes
Advisor: Davidson, Alan R
Improving Online Mirror Descent for Convex Optimization in Dynamic Environments

In many practical applications, system parameters and cost functions vary over time. For example, in online machine learning, data samples arrive dynamically, so that the learning model is progressively updated. It is difficult to capture such dynamics in an offline setting, while online optimization techniques naturally accommodate unpredictable variations in the system parameters. Online Convex Optimization (OCO) is a field in the intersection of optimization theory, machine learning, and control, which has recently attracted significant attention as an important tool for modeling various classes of problems in different application domains. One of the most popular algorithms in solving OCO problems is online mirror descent. Interesting theoretical and practical properties have made online mirror descent a powerful tool in solving large-scale and high-dimensional problems. However, the existing works on online mirror descent often make simplistic or impractical assumptions with respect to the cost functions and system model or propose inefficient solutions. In this dissertation, our aim is to propose efficient online algorithms based on mirror descent method with improved performance. We first consider the problem of distributed online convex optimization with a time-varying network topology. We propose the Distributed Online Mirror Descent with Multiple Averaging Decision and Gradient Consensus (DOMD-MADGC) algorithm in order to enable the local learners to accurately follow the sequence of global minimizers. We then consider a heterogeneous learning environment, where the processing speed can arbitrarily vary among the network nodes. We develop the Distributed Any-Batch Mirror Descent (DABMD) algorithm to speed up the progress of the network. Finally, we address the problem of centralized OCO without Lipschitz continuity. We show that it is still possible to guarantee the performance of online mirror descent algorithm even when Lipschitz continuity is not present. To further improve the performance, we propose the Online Multiple Mirror Descent (OMMD) algorithm that applied the mirror descent step multiple times to update the learner's decision. For each of these problems, we also use experimental results to compare against existing alternatives and study the performance of the proposed algorithms in various scenarios. We observe that the proposed online algorithms outperform other alternatives.

Keywords: Machine Learning
Online Convex Optimization
Advisor: Liang, Ben BL
Motion and Driving: How Different Types of Physical Motion Cues Influence Driving Performance and Simulator Sickness in Younger and Older Adults

Vestibular function changes with older age, but the effects of these changes on functional activities requiring self-motion perception are largely unknown. Driving is a complex task that involves the use of vestibular inputs to guide self-motion perception and behaviours. However, little is known about how different types of physical motion (i.e., vestibular cues), such as yaw motion and full motion (7-degree-of-freedom) affect driving performance differently in younger and older adults. Driving simulators offer an effective means of studying the effects of physical motion cues on driving outcomes in younger and older adults. Chapter 2 of this thesis investigated how different kinds of motion cues (no motion, yaw motion, and full motion) affected simulated driving performance in younger and older adults. Driving environments were made up of eight scenario elements (e.g., curves, hills, turns) to strategically target vestibular cues. Results demonstrated that physical motion cues did not systematically and consistently affect driving performance across all scenario elements. The general patterns,iii however, suggest that added motion cues lead to better driving performance for both age groups, with effects being particularly apparent for certain driving metrics (e.g., mean speed). Driving simulators are also known to induce simulator sickness in some users. The prevalence and severity of simulator sickness is influenced by different factors, including motion capabilities and time of exposure. It is hypothesized that simulator sickness may be the result of sensory conflicts (visual-vestibular) and therefore, adding different types of congruent physical motion cues to visual displays may reduce symptoms. Therefore, in Chapter 3 using the same driving scenarios as Chapter 2, I investigated how different types of physical motion cues (no motion, yaw motion, and full motion) affect simulator sickness, over time of exposure, between younger and older adults. The results demonstrated no main effect of motion condition or age on simulator sickness, however, the addition of motion cues prevented simulator sickness from increasing over time of exposure. Together this thesis contributes to a fundamental understanding of how physical motions of different types influence self-motion perception, driving behaviours, and simulator sickness, which may have implications for vehicle and simulator-related research and application.

Keywords: 7-degree-of-freedom
Aging
Driving Simulator
Self-Motion Perception
Turntable
Virtual Reality
Advisor: Campos, Jennifer L
Police Use of Force: Understanding its Impact on Indigenous and Black Community Members in Ontario

Police use of force is a critical area of concern, in Canada, North America, and globally. Issues around use of force have received considerable public attention in recent years due to several high-profile police-involved deaths of civilians, particularly racialized citizens. Using a mixed methods approach, this dissertation examines police use of force in Ontario and its impact on Indigenous and Black community members. An integrated framework of minority threat and social conflict theories, police working personality and symbolic interaction theories, and the concept of reputational risk is applied to help account for the findings. I argue that police use of force and its impact on certain communities is detrimental, multi-faceted, complex, and cannot be fully explained—in large part because of the lack of information made accessible on the subject. The qualitative section involves interviews with Indigenous and Black residents in Ontario to understand their perceptions of and experiences with police use of force. A primary finding is that many community members have been victims of police use of force—though, the types of force these members reported were overwhelmingly physical in nature (e.g., punching, kicking, knee-to-neck, roughhousing). Additionally, both Indigenous and Black individuals perceive that the police use force disproportionately against members from these groups compared to others. Moreover, the quantitative section provides an expansive analysis of police use of force over a 30-year period by examining use of force across all Ontario police services, lethal force incidents, and data from the Special Investigations Unit (SIU) to identify trends, patterns, and racial disparities in cases. Overall, the findings suggest that Indigenous and Black individuals in Ontario have been over-represented in use of force incidents consistently while other groups have been under-represented. The quantitative data also validate and support the perceptions and experiences shared by the Indigenous and Black community members. Despite the findings in this dissertation that highlight racial disparities in police use of force incidents, the limited information available on use of force by police services in Ontario underscores how much we do not know about this subject in the province. Future research and policy recommendations are provided.

Keywords: Canada
Indigenous and Black experiences
Ontario
police accountability
police use of force
policing
Advisor: Wortley, Scot
Understanding Organist Occupational Injury: An Epidemiological Study of Canadian Organists

Musicians constantly face the hazard of playing-related overuse injuries. Organists are at particular risk of Playing Related Musculoskeletal Disorders (PRMDs) as they face many challenges not encountered by other instrumentalists, including extreme patterns of motion required by all four limbs, uncontrollable practice hours, as well as many other factors. Since the 1980s, researchers have recommended approaches to injury prevention, and many schools of instruments have performed instrument-specific surveys to gather data, leading to the development of prevention techniques within their teaching pedagogies. While the amount of pre-existing information for organ playing injury prevention is minimal, there is already some evidence suggesting that musculoskeletal injury risk factors exist for organists. Unfortunately, the pre-existing information is not substantial enough for the development of data-driven prevention recommendations specific to organists, leaving the school of organ pedagogy to continue to root itself in inherited playing techniques uninformed by modern research on musician, and specifically, organist injury prevention. This thesis seeks to contribute to the literature on organist injury and injury prevention with the purpose of furthering organ pedagogy’s understanding of organists PRMDs. Using Occupational Health as a focus of research, I have collected data which can be used to confirm that organists have musculoskeletal health problems as well as to act as building blocks towards future research and pedagogical developments in injury prevention for the profession. The primary tool used for this research was an anonymous epidemiological survey distributed to the membership of the Royal Canadian College of Organists. The content and results of the survey relate to: basic demographics; practice and performance habits; individual belief systems in relation to conceptual barriers to normalizing PRMDs; the contextual use of prevention and/or treatment resources; upper and lower body symptoms of pain and function (self-reported); awareness of, access to, and understanding of injury prevention information; experience with Occupational Health and Safety; and, experiences with the COVID-19 pandemic.

Keywords: Health
Injury
Musician
Organist
Prevention
Workplace
Advisor: Gutsche-Miller, Sarah
“I Think My Teacher Likes Me”: The Role of the Teacher- Student Relationship on the Mathematical Engagement and Achievement of Students with Socio-emotional Difficulties

The purpose of this dissertation was to explore the impact of teacher-student relationship quality (TSRQ) on students’ mathematical engagement and achievement, while considering how socioemotional difficulties play a role across these variables. The goals of this two-study dissertation were to (1) determine the profiles that exist among elementary school students’ mathematics anxiety, engagement, and achievement, and then to explore whether TSRQ predicts profile membership (Study 1) and (2) determine whether TSRQ differentially impacts the mathematical engagement of students with more socio-emotional difficulties (Study 2). The study took place at an inquiry-based school that embraces a philosophy of building secure relationships. Ninetyseven students across Grade 1 and 6 participated. In Study 1, latent profile analysis was used to identify types and number of profiles. Results revealed three profiles: one with moderate levels of anxiety and engagement (Class 1), one with highest levels of anxiety and lowest engagement (Class 2), and the last with lowest levels of anxiety and highest engagement (Class 3). Across all three profiles, mathematics achievement was in the average range. Students with highest TSRQ were more likely to belong to Class 3, those with moderate TSRQ to Class 1, and those with the lowest TSRQ to Class 2. Overall, this study revealed that the school’s evidence-based practices allowed for adequate achievement regardless of anxiety or engagement levels, and that students with stronger TSRQ have a more positive mathematics experience. In Study 2, moderation analysis was used to determine whether TSRQ has a differential association with mathematical engagement at the beginning and end of the school year for students with higher levels of externalizing difficulties, internalizing difficulties, and mathematics anxiety. Results revealed TSRQ predicts mathematics engagement at the beginning and end of the school year across all students, however, at the beginning of the year, this relationship is stronger for students with more internalizing challenges. There was no differential association for students with externalizing difficulties or for any socio-emotional difficulties by the end of the year. Results suggest that for students with certain emotional difficulties, TSRQ may protect against low mathematics engagement at the beginning of the school year.

Keywords: Engagement
Math Achievement
Math Anxiety
Socio-Emotional Difficulties
Teacher-Student Relationship Quality
Advisor: Martinussen, Rhonda