UWSpace

UWSpace is the University of Waterloo’s institutional repository for the free, secure, and long-term home of research produced by faculty, students, and staff.

Depositing Theses/Dissertations or Research to UWSpace

Are you a Graduate Student depositing your thesis to UWSpace? See our Thesis Deposit Help and UWSpace Thesis FAQ pages to learn more.

Are you a Faculty or Staff member depositing research to UWSpace? See our Waterloo Research Deposit Help and Self-Archiving pages to learn more.

Photo by Waterloo staff

Communities in UWSpace

Select a community to browse its collections.

Recent Submissions

  • Thumbnail Image
    Item type: Item ,
    Categorical 't Hooft Expansion and Twisted Holography
    (University of Waterloo, 2026-06-15) Lopez Raven, Adrian Khalil
    This thesis studies ideas of Holography and 't Hooft expansions in the context of Twisted Holography. The 1st part introduces a novel entry in the Twisted Holography dictionary, associating to certain boundary operators, bulk instantonic deformations of D1-D5 brane systems in SL(2,C). From the boundary operators, we are able to extract the data of both the shape and Chan-Paton bundle of the dual brane, encoding it in a derived coherent sheaf. We then apply this construction to chiral algebras with SO and Sp gauge groups, obtaining branes with Z2 identifications consistent with conjectures relating these chiral algebras to orientifolds of the bulk B-model theory. The second part, extends the conjecture of Twisted Holography to a wide family of chiral algebras. In particular, we study boundary theories containing several βγ-systems with several U(N) gauge groups. Amongst these one has known chiral algebras arising from the twist of quiver-gauge theories, but also new chiral algebras whose dual B-model lives in non-commutative backgrounds. Using techniques from String Field Theory and Homological Algebra, we extract from these chiral algebras, algebraic properties of the conjectural dual worldsheet theories, and track how they deform under backreaction.
  • Thumbnail Image
    Item type: Item ,
    Evaluating the effectiveness of France's indoor smoke-free law 1 year and 5 years after implementation: Findings from the ITC France survey
    (Public Library of Science, 2013-06-21) Fong, Geoffrey T.; Craig, Lorraine V.; Guignard, Romain; Nagelhout, Gera E.; Tait, Megan K.; Driezen, Pete; Kennedy, Ryan David; Boudreau, Christian; Wilquin, Jean-Louis; Deutsch, Antoine; Beck, Francois
    France implemented a comprehensive smoke-free law in two phases: Phase 1 (February 2007) banned smoking in workplaces, shopping centres, airports, train stations, hospitals, and schools; Phase 2 (January 2008) banned smoking in hospitality venues (bars, restaurants, hotels, casinos, nightclubs). This paper evaluates France’s smoke-free law based on the International Tobacco Control Policy Evaluation Project in France (the ITC France Project), which conducted a cohort survey of approximately 1,500 smokers and 500 non-smokers before the implementation of the laws (Wave 1) and two waves after the implementation (Waves 2 and 3). Results show that the smoke-free law led to a very significant and near-total elimination of observed smoking in key venues such as bars (from 94–97% to 4%) and restaurants (from 60–71% to 2–3%) at Wave 2, which was sustained four years later (6–8% in bars; 1–2% in restaurants). The reduction in self-reported smoking by smoking respondents was nearly identical to the effects shown in observed smoking. Observed smoking in workplaces declined significantly after the law (from 41–48% to 18–20%), which continued to decline at Wave 3 (to 14–15%). Support for the smoke-free laws increased significantly after their implementation and continued to increase at Wave 3 (p<.001 among smokers for bars and restaurants; p<.001 among smokers and p = .003 for non-smokers for workplaces). The findings demonstrate that smoke-free policies that are implemented in ways consistent with the Guidelines for Article 8 of the WHO Framework Convention on Tobacco Control (WHO FCTC) lead to substantial and sustained reductions in indoor smoking while also leading to high levels of support by the public. Moreover, contrary to arguments by opponents of smoke-free laws, smoking in the home did not increase after the law was implemented and prevalence of smoke-free homes among smokers increased from 23.2% before the law to 37.2% 5 years after the law.
  • Thumbnail Image
    Item type: Item ,
    Representing Sexual Violence and Sexual Violence on Campus: Institutional Constructions, Student and Staff Perceptions, and Their Effects
    (University of Waterloo, 2026-06-15) Goodall, Jade
    Universities have increasingly been positioned as key sites of sexual violence prevention and response, yet little attention has been paid to how they construct and represent sexual violence through the institutional texts they produce. This study examines how sexual violence and sexual violence prevention are represented within university polices and prevention materials, and how these representations are perceived and understood by students and staff. This qualitative study draws on a textual analysis of 130 institutional documents and semi-structured interviews with 10 students and staff at a Southwestern Ontario university (referred to as Z University). Guided by Bacchi’s (2009) What’s the Problem Represented to Be? approach, and drawing on theoretical insights from Dorothy Smith (2005) and Patirica Hill Collins (2019), the analysis examines how sexual violence is represented, the assumptions that underpin these representations, what is left unspoken, and how these representations are taken up in practice. The findings demonstrate that sexual violence is predominately framed as a matter of legal compliance, public health education, and individual responsibility. Participants describe tensions between institutional representations and lived experience, particularly among those who feel excluded or misrepresented within dominant framings. Rather than producing generalizable claims, this study offers a critical, context-specific analysis of how sexual violence and sexual violence prevention are constructed within institutional settings and how these constructions are perceived and negotiated by students and staff.
  • Thumbnail Image
    Item type: Item ,
    On Initializations for NMF
    (University of Waterloo, 2026-06-15) Shi, Sammy
    In Ward and Kolda (2023) and Xu et al. (2024), the authors proposed a sketching based initialization for unconstrained two block matrix factorization (MF) with provable guarantee. The purpose of this thesis is to examine the limits of extending these two proof frameworks in the context of Non-negative Matrix Factorization (NMF), as well as its numerical implications. The first chapter deals with fundamentals of NMF: its formulation, the identifiability issue and guarantees, a survey of iterative methods to solve it, and finally some complexity results. In the second chapter, I will quickly go over spectral initialization techniques for matrix optimization problems, and introduce sketching, a family of randomization techniques for numerical linear algebra, with a particular focus on its uses in iterative methods. The core focus of this chapter lies at the intersection of these two topics: a sketching-based initialization for the unconstrained two-block MF problem, using either non-alternating or alternating gradient descent (GD). We will go over the proof frameworks. In the third chapter, I will present my attempts to generalize the proof frameworks to NMF and the conclusions based on the partial progress. The fourth chapter deals with numerics. We will compare the performance of different base methods in different data regimes using all of the initializations mentioned in this thesis.
  • Thumbnail Image
    Item type: Item ,
    Recalibrating Reality: Sensory Reweighting and Cybersickness Susceptibility in Virtual Reality
    (University of Waterloo, 2026-06-15) Izadi Sokhtabandani, Siyavash
    This dissertation investigates how the brain dynamically reweights sensory cues to resolve multisensory conflicts in virtual reality (VR), with a specific focus on the etiology of cybersickness. The research characterises how visual, vestibular, and proprioceptive cues are integrated and recalibrated following VR gameplay while accounting for individual differences in these processes which dictate susceptibility to sickness. Across three experiments, this work challenges the assumption that VR exposure triggers a uniform sensory shift. Experiment 1 utilised the Subjective Visual Vertical (SVV) task, finding that high-intensity exposure shifted participants' perceived upright toward gravitational vertical and away from the body axis. Crucially, individuals who demonstrated greater reweighting reported lower cybersickness, suggesting that rapid sensory adaptation acts as a protective mechanism. Experiment 2 employed the Oriented CHAracter Recognition Test (OCHART) to further tease apart the relative weighting of visual and gravitational cues. While VR exposure did not produce a uniform group-level shift in the Perceptual Upright (PU), exploratory analyses revealed that increased visual weighting post-exposure was associated with higher cybersickness, indicating that a failure to down-weight unreliable visual inputs may be maladaptive. Experiment 3 attempted to manipulate these weights by degrading vestibular reliability through stochastic electrical vestibular stimulation (EVS). Contrary to the hypothesis that reducing vestibular certainty would force a beneficial reweighting, EVS exacerbated cybersickness and increased attrition, while cue-weighting models remained unstable. Altogether, this work demonstrates that cybersickness is not merely a product of sensory conflict, but a failure of the central nervous system to successfully reweight unreliable cues. The results suggest a two-part interpretation: first, that individual differences in sensory plasticity may relate to tolerance, where greater post-VR shifts toward gravitational cues were associated with lower symptom severity in Experiment 1, though this relationship was not consistent across tasks and measures. Second, the results suggest that external disruption of vestibular signals (via EVS) may hinder rather than help adaptation. These findings provide preliminary evidence for a reweighting account of individual differences in cybersickness susceptibility and point toward personalised exposure protocols as a candidate intervention, pending replication with larger and more diverse samples.