Theses

Permanent URI for this collectionhttps://uwspace.uwaterloo.ca/handle/10012/6

The theses in UWSpace are publicly accessible unless restricted due to publication or patent pending.

This collection includes a subset of theses submitted by graduates of the University of Waterloo as a partial requirement of a degree program at the Master's or PhD level. It includes all electronically submitted theses. (Electronic submission was optional from 1996 through 2006. Electronic submission became the default submission format in October 2006.)

This collection also includes a subset of UW theses that were scanned through the Theses Canada program. (The subset includes UW PhD theses from 1998 - 2002.)

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Investigating the Potential Role of Pic2 protein in Mitochondrial Copper Transport using Saccharomyces cerevisiae
(University of Waterloo, 2025-12-12) Kurnosova, Anastasiia
Copper (Cu) is an essential metal required for the assembly and activity of two key mitochondrial enzymes: cytochrome c oxidase (COX) and superoxide dismutase (SOD1), which are responsible for energy metabolism and antioxidant defence, respectively. For the past decade, Pic2 has been generally accepted as the main mitochondrial copper transporter, delivering copper to COX and SOD1, both of which cannot function without this essential metal. However, this model of copper transport in mitochondria had many inconsistencies and required revision due to conflicting data in the literature and more recent findings suggesting that Pic2 is not involved in copper transport. In this project, I hypothesized that Pic2 is not the primary copper transporter for COX and SOD1 and used various approaches, comparing wild-type yeast with a Pic2 deletion strain in the W3030 background, to test the role of Pic2 in copper transport. Growth assays under varying copper concentrations revealed no differences in growth phenotypes between strains and enzymatic assays further demonstrated that loss of Pic2 does not lead to reduced COX or SOD1 activity. Considering that the activity of both enzymes depends on sufficient copper levels in mitochondria, these results suggest that Pic2 is not essential for mitochondrial copper transport. Additionally, measurement of aconitase activity showed that Pic2 deletion had no effect on oxidative stress, thus further supporting the notion that copper homeostasis in mitochondria is maintained in the absence of Pic2. Together, my findings show that Pic2 cannot be the main copper transporter and that its role needs to be reevaluated, given that a better understanding of the mechanism of copper transport into mitochondria could provide new insights into both a subset of mitochondrial and copper-dependent disorders.
Tool Wear Modeling for Application to Gear Shaping
(University of Waterloo, 2025-12-11) Kropp, Alexander
Tool wear has a major impact on the productivity, economics, and sustainability of metal machining operations. While the topic of tool wear has been studied extensively for conventional metal cutting processes, like milling, turning, and drilling, there is a scarcity of studies in literature on modeling and predicting tool wear in gear machining operations. Gears, on the other hand, are essential components for a vast array of engineered systems, like automotive, aerospace, and various transportation vehicles, robotics, automation, and general machinery. This thesis has targeted developing a framework for the study and prediction of tool wear in the gear shaping operation. Gear shaping is among the most versatile methods of cutting gears. In-house experiments were designed and performed to replicate the gear shaping process on a 5-axis milling machine. The kinematics were modeled, and custom NC code was generated and validated using polygon subtractions, to ensure that a gear shaping cutter would accurately produce a gear workpiece. The testing conditions were designed considering the physical capabilities of the machine tool, and the utilization of digital simulations of the gear cutting operation via ShapePro software (previously developed at the University of Waterloo), that predicts the kinematics, chip geometry, and cutting forces. As such, specimen gears were produced from AISI 1215 mild steel using HSS (high-speed steel) cutter material. The cutting edges and flanks of the tool were imaged throughout the tests, to monitor the development of wear. In the envelope of cutting speeds and feed rates that could be tested, only minimal wear was observed, and this was concentrated at the cutting tooth tips and corners, consistent with the prediction from ShapePro that these regions are subject to the largest chip thickness and longest distance of workpiece material cut. Nevertheless, these tests have demonstrated the proof-of-concept for performing shaping tests and progressively imaging the tool edges for wear. Future tests should focus on performing the cuts at more aggressive speeds and feeds to induce discernable wear. To facilitate rapid characterization of tool wear for different workpiece and tool material pairs, an analogy testing method was also developed as an interrupted cutting operation on a lathe, designed to mimic cutting conditions similar to those in shaping. With this approach, a broader set of cutting speeds and feed rates could be explored in the machining of a similar kind of material (cold rolled 1020 steel). In this case, using HSS tooling brought practical limitations (e.g., built-up edge), thus the tooling material was changed to carbide. Nevertheless, a reasonable variation of cutting conditions could be implemented and tool wear progression data, as a function of cutting distance (and time) be documented. This data has informed the development of a progression-based tool wear model for predicting flank wear in interrupted cutting, which is presented as a new contribution in this thesis. Established tool life models, such as Taylor and Colding, can predict the cutting time required for reaching only a single value of tool flank wear, whereas the proposed model can be used to predict when different values of tool wear would be reached without requiring re-calibration. More importantly, the proposed model can be integrated inside a time-domain simulation of an interrupted cutting operation, like gear shaping, in order to predict and update the wear state along each node on the tool edge, which classical tool life models cannot achieve, as they are ‘tuned’ to predict the cutting time until a preset wear is reached. The proposed model, as well as Taylor and Colding models, were benchmarked with respect to the experimental wear data collected across 12 different cutting conditions, and they all performed comparably in predicting tool life, with average prediction errors of roughly 21%-24%, thus indicating some confidence in the proposed new model. Future research should focus on collecting further data, both in gear shaping and analogy orthogonal testing experiments, to ensure further repeatability of the data, as well as validating that a tool wear model calibrated using the lower cost and faster analogy experiments can indeed predict the distribution of tool wear progression in the much more complex gear shaping operation. Furthermore, it is also advised to expand the wear model to predict uncertainty bounds along with the tool wear values themselves, and to expand the study into the machining of different kinds of metals, with different tools substrates and coatings.
Multiple Model Adaptive Control with Blending in State Space
(University of Waterloo, 2025-12-11) Lovi, Alex
Adaptive Control (AC) provides a systematic framework for handling uncertainty in linear and non-linear systems. Single-model adaptive schemes such as Model Reference Adaptive Control (MRAC) and Adaptive Pole Placement Control (APPC) face inherent limitations when applied to systems with large parametric uncertainty, such as slow convergence rates and limited noise robustness. This has motivated researchers to investigate multiple-model strategies that employ several candidate plants to represent different regions of the operating space. In this thesis, we develop Multiple-Model Adaptive Control (MMAC) methodologies based on the blending of signals from multiple fixed models. We consider uncertain plants with known, compact, convex polytopic uncertainty. Our starting point is the design of a Multiple-Model Parameter Identification (MMPI) scheme that quickly and robustly identifies the uncertain plant parameters. In combination with a Model Reference Control (MRC) framework, this leads to a Multiple-Model Reference Adaptive Control (MMRAC) with blending for Linear, Time-Invariant (LTI), non-square (different number of inputs and outputs), multi-input systems, with full-state feedback. Under an exact matching condition, the parameter estimates are used to design a control input such that the plant states asymptotically track the reference signal generated by a state-space reference model. A procedure is provided to select the corner models based solely on the polytopic uncertainty. The proposed MMRAC guarantees the boundedness of all closed-loop signals and the asymptotic convergence of the state-tracking error to zero. Statistical analysis demonstrate improved tracking speed and robustness to noise compared with single-model approaches. The combination of MMPI with pole-placement techniques, allowed us to develop Multiple-Model Adaptive Pole Placement Control (MMAPPC) for LTI, square (same number of inputs and outputs), multivariable systems with full-state feedback, and for with LTI, Single-Input, Single-Output (SISO) systems via an intermediate state estimation step. The resulting controller again ensures the boundedness of all closed-loop signals, while also asymptotically placing the closed-loop eigenvalues at designer-specified locations. Statistical analysis shows a clear increase in robustness to noise relative to single-model schemes. These improvements were validated in the context of motion control of lateral vehicle dynamics, where multiple-model schemes consistently outperformed single-model approaches, including cases with slowly time-varying unknown parameters.
Algorithmic Collective Action under Differential Privacy
(University of Waterloo, 2025-12-11) Solanki, Rushabh
The rapid integration of AI into everyday life has generated considerable public attention and excitement, pointing to unprecedented gains in efficiency and personalization. However, it concurrently raises concerns about the potential for automating algorithmic harms, as well as re-entrenching existing social inequities. In response, the pursuit of "trustworthy AI" has become a critical goal for researchers, corporations, and governments alike. Achieving this objective is a complex challenge with many possible ways to realize it, ranging from policy and regulation to technical solutions such as algorithmic design, systematic evaluation, and enhanced model transparency. Contemporary AI systems, particularly those leveraging large-scale models, are fundamentally trained on vast amounts of data, often sourced from social interactions and user-generated content. This dependence introduces a grassroots mechanism for autonomy: the possibility for everyday users, citizens, or workers to directly steer AI behavior. This concept, known as Algorithmic Collective Action (ACA), involves a coordinated effort where a group of individuals deliberately modifies the data they share with a platform, with the intention of driving the model’s learning process toward outcomes they regard as more favorable or equitable. We investigate the intersection between these bottom-up, user-driven efforts to influence AI and a growing class of methods that firms already implement to improve model trustworthiness, especially privacy protections. In particular, we focus on the setting in which an AI firm deploys a differentially private model, motivated by the growing regulatory focus on privacy and data protection. Differential Privacy (DP) is a formal, mathematical framework that provides provable guarantees about the privacy of individuals whose data are used in a dataset. To operationalize these privacy guarantees in deep learning settings, we employ Differentially Private Stochastic Gradient Descent (DP-SGD), which is the de facto DP mechanism for deep learning, making it a natural choice for assessing the effectiveness of ACA under realistic conditions. Our findings reveal that while differential privacy offers substantive protection for individual data, it concurrently introduces challenges for effective algorithmic collective action. Theoretically, we characterize formal lower bounds on the success of ACA when a model is trained with differential privacy. These bounds are expressed as a function of key variables: the size of the acting collective and the firm’s chosen privacy parameters, which dictate the level of privacy the firm intends to enforce. Empirically, we verify these theoretical trends through extensive experimentation by simulating collective action during the training of a deep neural network classifier across several datasets. Moreover, we offer additional insight into how ACA affects empirical privacy, and we include a socio-technical discussion of the wider implications for responsible AI.
Deterministic and Probabilistic Bijective Combinatorics for Macdonald Polynomials
(University of Waterloo, 2025-12-11) Dantas e Moura, Guilherme Zeus
Permuted-basement Macdonald polynomials 𝐸^𝜎_𝛼(𝐱; 𝑞, 𝑡) are nonsymmetric generalizations of symmetric Macdonald polynomials indexed by a composition 𝛼 and a permutation 𝜎. They form a basis for the polynomial ring ℚ(𝑞, 𝑡)[𝐱] for each fixed permutation 𝜎. They can be described combinatorially as generating functions over augmented fillings of composition shape 𝛼 with a basement permutation 𝜎. We construct deterministic bijections and probabilistic bijections on fillings that prove identities relating 𝐸^𝜎_𝛼, 𝐸^{𝜎𝑠ᵢ}_𝛼, 𝐸^𝜎_{𝑠ᵢ𝛼}, and 𝐸^{𝜎𝑠ᵢ}_{𝑠ᵢ𝛼}. These identities correspond to two combinatorial operations on the shape and basement of the fillings: swapping adjacent parts in the shape, which expands 𝐸^𝜎_𝛼 in terms of 𝐸^𝜎_{𝑠ᵢ𝛼} and 𝐸^{𝜎𝑠ᵢ}_{𝑠ᵢ𝛼}; and swapping adjacent entries in the basement, which gives 𝐸^𝜎_𝛼 = 𝐸^{𝜎𝑠ᵢ}_𝛼 when 𝛼ᵢ = 𝛼ᵢ₊₁.
Selbstbestimmt: The Woman in Contemporary German Women’s Filmmaking
(University of Waterloo, 2025-12-11) Provida, Myrto
Women’s representation in film has become an increasingly relevant topic in gender and film discourse, challenging the postfeminist claim that gender equality has been achieved and feminist critique is no longer necessary. German cinema in particular has recently experienced renewed scrutiny for its evident gender inequality, with scholarship pointing to the underrepresentation of women both on and off the screen, a pattern that reflects enduring structural barriers within the industry. Despite graduating in equal numbers as men from film schools, women direct fewer than 25% of the feature films released in Germany, receive less than 20% of all available funding, and are significantly underrepresented as directors, writers, and producers. At the same time, female figures in German films are “visible but not diverse:” the average German cinematic woman is slim, white, heterosexual, in her teens, twenties, or thirties, and more likely to be shown in the context of relationships or partnerships than in work environments. Yet when women occupy key filmmaking positions, not only do they work with more women behind the screen, but they also construct more complex female characters, foregrounding female subjectivity in diverse contexts. This dissertation attaches itself to questions of women’s representation in German cinema by examining three contemporary films directed by women in order to to explore how they engage with womanhood through their female protagonists. The first, both chronologically and analytically, is Maren Ade’s Toni Erdmann (2016), which centres on the relationship between business consultant Ines and her father, who unexpectedly visits her. An international critical and commercial success, Toni Erdmann has exerted wide influence on the German cinematic landscape, drawing significant attention on its portrayal of gendered subjectivity. The second is Annika Pinske’s Alle reden übers Wetter (2022), which follows doctoral candidate Clara’s return to her hometown to celebrate her mother’s birthday. Despite being the most recent of the three films analyzed, Alle reden übers Wetter is placed after Toni Erdmann due to its contextual and aesthetic parallels to Ade’s film, as Pinske—the only director among the three who hails from the former East, a rarity among German women filmmakers—worked closely with Ade and adopts a similarly realist aesthetic in her debut feature, which presents a range of multidimensional female characters. Finally, the dissertation examines Sherry Hormann’s Nur eine Frau (2019), which dramatizes the life of Hatun “Aynur” Sürücü, a German woman of Kurdish background who was murdered by her brother at a Berlin bus stop in 2005. The film is discussed last not only because it diverges from Ade’s and Pinske’s works through its highly stylized form, but also because it engages with a distinct subject matter—migration and Islam—through a real-life case that remains central to German debates on cultural difference and integration. A close reading of the formal and narrative strategies in these films reveals a multifaceted engagement with gendered subjectivity by contemporary German women directors, whose protagonists are constructed as complex characters navigating intersecting pressures and gendered demands. Central to these trajectories is the pursuit of self-determination, which emerges across all three works as an ongoing process marked by the continuous negotiation of often conflicting roles—as daughters, mothers, partners, and friends. While these films stop short of articulating a collective dimension of self-determination, instead adopting an individualized lens reflecting postfeminist discourse, they nonetheless articulate a shared feminist consciousness by exposing and challenging gendered scripts and essentialist notions of womanhood. By foregrounding self-determination as an analytical lens, this dissertation demonstrates how these films articulate feminist modes of resistance on screen while their production contexts reveal parallel struggles for autonomy off screen. Moreover, by bringing two largely unexamined films into scholarly conversation—Alle reden übers Wetter and Nur eine Frau—the project expands the representational and analytical space of German women’s filmmaking and illuminates the diverse ways women directors intervene in, reshape, and critically reimagine dominant cultural narratives about womanhood. Ultimately, the analysis shows that contemporary German women filmmakers and their protagonists enact a mode of agency and resistance that foregrounds their struggle to live and create selbstbestimmt.
A Framework for Explaining LLM Reasoning with Knowledge Graphs
(University of Waterloo, 2025-12-10) Shirdel, Moein
Large Language Models (LLMs) have demonstrated remarkable question-answering (QA) capabilities, yet their decision processes and outputs often remain opaque and prone to factual inconsistencies. While existing methods evaluate or ground LLM outputs after generation, they typically lack mechanisms for aligning LLM reasoning with external knowledge sources. This thesis introduces Apr`esCoT, a lightweight model-agnostic framework that validates LLM reasoning by grounding it in an external knowledge graph (KG). Apr`esCoT operates through three main components: Subgraph Retrieval, which extracts a KG subgraph relevant to a given query; Triple Extraction and Parsing, which converts the LLM’s output into factual triples; and Matching, which aligns these triples with entities and relations in the extracted KG subgraph. The integration of these modules enables alignment between LLM reasoning and structured knowledge, producing traceable and structured explanations alongside model outputs. We evaluate alternative retrieval and matching strategies, analyze their trade-offs, and demonstrate how Apr`esCoT helps users surface reasoning gaps, hallucinations, and missing facts. Experiments across multiple domains, including large-scale KGs, highlight Apr`esCoT’s effectiveness in advancing trustworthy and explainable AI.
Immersion, Roleplaying, Narrative Design: Concepts for Understanding Videogame Narrative
(University of Waterloo, 2025-12-10) Franiczek, Aleksander
Single-player videogames have been at the forefront of public and academic conversations about the supposed novelty of digital, interactive narratives for the past 30 years. This perceived novelty, together with the digital medium’s capacity for remediating the aesthetics of prior popular media such as novels, film, performance, and of course games, has spurred conflicting discussions about its ontological and teleological nature. Whether one listens to game scholars, developers, or players, there is no single answer that encapsulates the wide range of disciplinary perspectives and personal fixations that make videogames interesting and meaningful. This project therefore synthesizes a range of research across disciplines to address a longstanding yet still insufficiently explored area of videogame inquiry: their historical creation, function, and consumption as a form of narrative. This dissertation examines how narrative meaning in single-player videogames emerges in the interaction between the material, rhetorical, and formal properties of the game as well as the imaginative engagement and individual experience of a given player. In other words, it delves into how narrative has been conceived and discussed around games, how players cultivate and interpret their gameplay as a narrative experience, and how developers leverage the multimodal potential of videogames towards narrative-driven expression. It does so through a synthesis of research around three interrelated key terms: immersion, role-playing, and narrative design. The terms immersion and roleplaying help explore how a player’s involvement in the role of a digital avatar—established through the identity and affordances presented by the game’s design and the player’s creative engagement with those fixed elements—can offer a means for subject formation, self-reflection, and critical interpretation. This involves exploring these concepts’ relations between narrative (Murray), digital technology (Coleman), and the self (Gee). The project then examines how this critical engagement textually stems from the player’s experience of a game’s narrative design: a game design concept and development practice related to the coherent integration of a game’s processes, its representational content, and the thematic and subjective meanings players uncover through the narrative event of gameplay (Berger). This framework can help develop greater literacy of the unique ways in which a videogame’s textual meaning is co-constructed between a game’s procedurality, representations, creators, and players. These topics are supported by case studies of games—predominantly role-playing games, or RPGs—that leverage the expressiveness of the medium towards innovations in digital, interactive storytelling. By situating these discussions of videogame narrative with texts that tackle videogames’ unique media aesthetics (Calleja), indebtedness to prior media (Saler), black-boxed creation process (Švelch), genre in cross-cultural creative contexts (Hutchinson and Pelletier-Gagnon), historical marginalization and entanglements with queer (Ruberg) and femme (Chess) folks, and other relevant topics, this dissertation analyzes the ways that single-player videogames can offer narrative experiences that combine the aesthetic and technical in ways that recontextualize the self’s involvement in fictional engagement.
Wideband Reconfigurable Intelligent Surfaces
(University of Waterloo, 2025-12-10) Tayebpour, Jalaledin
Reconfigurable intelligent surfaces (RISs) have emerged as one of the most significant innovations in wireless communications, offering a novel approach to meeting the escalating demand for higher data rates, seamless coverage, and energy-efficient connectivity in next-generation networks. Unlike conventional wireless systems that rely on active and power-hungry components, RIS leverages nearly passive reflecting elements arranged in a planar array, whose electromagnetic responses can be dynamically reconfigured. By enabling programmable control over the incident wavefront, RIS introduces a new paradigm in which the wireless environment itself becomes a controllable entity. This capability not only enhances system performance but also reduces overall power consumption and hardware complexity, positioning RIS as a key enabler for sixth-generation (6G) and beyond communication technologies. This thesis provides a comprehensive investigation into the principles, design methodologies, and system-level benefits of RIS technology. The research begins with an in-depth review of the current state of the art, highlighting both theoretical foundations and practical implementations of RIS. Building on this foundation, the work develops novel design strategies for reconfigurable unit cells intended for RIS applications. Several geometries are explored with the goal of achieving tunable reflection phase profiles, wide operational bandwidth, and multi-polarization capability. The designs integrate semiconductor switches and micro-electromechanical systems (MEMS) actuators, demonstrating the feasibility of programmable reconfigurability while addressing practical fabrication challenges . To validate the proposed concepts, the designed unit cells are extended into array structures, where their performance is evaluated through both simulation and experimental testing. A practical prototype of a 1-bit reflectarray is fabricated and tested in an anechoic antenna chamber. The prototype demonstrates the key required functionalities, including beam steering, wideband operation, and dual-polarization control. These results confirm the potential of RIS to dynamically manipulate electromagnetic propagation in real-world scenarios. Furthermore, the thesis addresses critical implementation issues related to the scalability of RIS, the integration of control circuitry, and the trade-offs between design complexity and achievable performance. The findings presented in this research underscore the innovative role of RIS in reshaping the architecture of wireless communication systems. By turning the propagation environment into an intelligent and programmable medium, RIS has the potential to significantly improve spectral efficiency, energy utilization, and overall network adaptability. The contributions of this thesis extend the understanding of RIS operation, provide novel unit cell structures, and deliver practical insights for prototyping and implementation. In doing so, this work not only advances academic knowledge in the field but also offers practical guidelines for industrial adoption of RIS in future wireless systems. Ultimately, this research highlights the promise of RIS as a cornerstone technology for realizing the vision of 6G and beyond.
A Multi-Scale Modelling Approach to Valuing Ecosystem Services In and Around Long Point Biosphere Region
(University of Waterloo, 2025-12-10) McAllister, Ceileigh
Ecosystem services are the benefits that humans derive from ecosystems, and they deliver significant economic value to local and global beneficiaries, yet they are often underrepresented in conventional economic decision-making. Valuing ecosystem services makes the contributions of nature visible in decision-making arenas, which supports holistic evaluation of tradeoffs in the policy-making process. The objective of this study is to value diverse ecosystem services at three scales around Long Point Biosphere Region, which is a protected area along the north shore of Lake Erie and part of the World Network of Biosphere Reserves. To address this objective, this study employs replacement cost and benefit transfer methods to conduct these valuations. The results of this study show, first, that the value of stormwater retention services provided by natural assets in Port Dover, a township near Long Point Biosphere Region, was found to be at least 2.6 million 2025 CAD per year. Second, the value of nutrient retention services provided by natural assets in the Long Point Region watershed was found to be at least 2.7 million 2025 CAD per year. Third, the value of a bundle of ecosystem services in the Long Point Biosphere Region Core was found to be 8 million to 87 million 2025 CAD per year. Each model was evaluated for resemblance to likely real-world ecosystem conditions. This analysis found that models for Port Dover and the Biosphere Core were defensible, while the model for the larger watershed was too different from likely real-world ecosystem conditions. These models are important to build narratives about the economic value of local ecosystems to community members, but cannot be used empirically in the absence of formal model validation.
Democratizing and Modernizing Information Access: From Open Rerankers to Scalable RAG Evaluation
(University of Waterloo, 2025-12-09) Pradeep, Ronak
Modern information access increasingly relies on complex pipelines involving large language models (LLMs), fundamentally changing how users interact with information, from sophisticated multi-stage retrieval pipelines to end-to-end retrieval-augmented generation (RAG) systems. While these advancements enhance user experience, they also introduce significant challenges. The research community's growing reliance on proprietary, black-box models for key tasks like document reranking creates barriers to innovation and reproducibility (the Component Challenge). Furthermore, progress is hampered by the lack of a shared, standardized ecosystem for executing and measuring information access systems (the Benchmarking Challenge). Finally, the generative nature of RAG systems makes them fundamentally harder to evaluate than traditional systems that return document lists; new methodologies are required to assess factual accuracy and completeness in a reliable, scalable manner (the Evaluation Challenge). We argue that progress depends on the synergistic development of open, high-effectiveness system components and the reliable, scalable evaluation frameworks necessary to assess them. This thesis addresses these challenges through a narrative arc that begins with pushing existing paradigms to their limits. But, given that frontier models dominate today's landscape, we find a pressing need for new open-source solutions. We begin by analyzing the dominant supervised ranking paradigm, developing multi-stage pipelines that demonstrated high effectiveness but also highlighted inherent complexity and cost. Subsequently, we conducted a systematic exploration of model backbones, loss functions, and negative mining strategies to squeeze effectiveness gains from supervised pointwise cross-encoders. Next, we continue with a large-scale empirical study on the newly evolving generative retrieval paradigm, which revealed its scalability limitations on large, real-world collections. This portion culminates in the final contribution to the Component Challenge: RankZephyr, an open-source 7B-parameter listwise reranker. By leveraging a carefully designed instruction distillation curriculum, RankZephyr matches and often surpasses the effectiveness of much larger proprietary models like GPT-4. It provides the community with a powerful, transparent, and accessible zero-shot reranking module, breaking the dependence on black-box systems for this critical task. All methods described have broad community adoption, and our models and evaluation frameworks continue to support ongoing research efforts across open-source IR and RAG development. With powerful open components in hand, the focus shifts to benchmarking. To address the Benchmarking Challenge, this work introduces Ragnarök, a reusable, end-to-end RAG framework designed to standardize how retrieval-augmented generation systems are constructed and assessed. Serving as the backbone for the TREC 2024 Retrieval-Augmented Generation Track, Ragnarök provides the research community with a shared experimental platform, critical data resources, and reproducible and effective baselines. By encapsulating the full RAG pipeline — from retrieval and grounding to generation and scoring — within a single, transparent framework, TREC 2024 Retrieval-Augmented Generation Track and Ragnarök enable reproducible experimentation at scale. This not only ensures fair comparisons across diverse approaches but also establishes a foundation for cumulative progress in open-domain information access research, where previously ad hoc and non-replicable setups have often impeded reliable evaluation. Building on this infrastructure, the thesis then directly tackles the Evaluation Challenge by introducing the AutoNuggetizer framework. This framework refactors the classic and well-studied nugget-based evaluation methodology for the modern era of LLMs. By automating the evaluation of the recall of the information nugget in RAG responses and validating the approach at scale in TREC 2024 Retrieval-Augmented Generation Track, this work provides a reliable and scalable methodology to measure the quality of generative information access systems. In summary, this thesis contributes to the field of information access by exploring the limits of existing retrieval and ranking paradigms, developing powerful open-source components for modern information access systems, and creating the frameworks and methodologies required to benchmark and evaluate them. The contributions include a comprehensive analysis of supervised ranking and generative retrieval paradigms, an open-source state-of-the-art listwise reranker (RankZephyr), a standardized framework for RAG benchmarking (Ragnarök), and a scalable methodology for evaluating generative systems (AutoNuggetizer). Together, this thesis addresses the three core challenges identified at the outset, providing the community with both the tools to build effective systems and the methodologies to assess them rigorously. The widespread adoption of these artifacts by researchers and practitioners already underscores their tangible impact and utility in driving the field forward. In the future, on the reranking front, we would like to build faster, more efficient rerankers that can reason over the texts and generalize to several domains. On the benchmarking front, we will expand tasks to capture "deep research" information needs that demand multi-hop reasoning and query decomposition. On the evaluation front, we hope to extend the AutoNuggetizer methodology to several tasks that go beyond web retrieval, into other domains like biomedical texts and conversational question answering.
Real-Time Assessment of Pain and Physical Activity in Knee Osteoarthritis: The Moderating Roles of Self-Efficacy, Fear of Movement, and Locus of Control
(University of Waterloo, 2025-12-09) Almaw, Rachel
Knee osteoarthritis (OA) is a highly prevalent chronic musculoskeletal condition and growing health concern in Canada. Characterized by loss of articular cartilage in the joint and fluctuating pain, knee OA is a leading contributor to physical and psychosocial disability (Steinmetz et al., 2023). By 2041, knee OA will affect over 10 million Canadians, driven by an aging and obese population (Sharif et al., 2017). Physical activity (PA) is recommended for knee OA management to reduce pain; but pain is commonly cited as a barrier to engagement (Bannuru et al., 2019). The links between PA exposure and pain are unclear. Current assessment tools cannot capture the temporal relationship between pain and PA in knee OA, as each dynamically influences the other throughout the day. This dynamic relationship is further complicated by psychosocial factors, including fear of movement, self-efficacy, and locus of control, which are associated with altered pain perception and PA behaviour in knee OA (Bayrak & Alkan, 2025). Yet, their roles in shaping the temporal relationship between pain and PA remain unclear in real-world contexts. Objectives and Hypothesis The primary objective of this study was to determine whether psychosocial factors (fear of movement, self-efficacy, and locus of control) moderate the temporal relationship between pain and subsequent PA in knee OA. The secondary objective examined the reverse temporal association: whether these psychological factors moderated the effect of PA on subsequent pain. It was hypothesized that (1) pain would reduce subsequent PA, with higher self-efficacy and internal locus of control weakening this negative effect and higher fear of movement strengthening the association; and (2) PA would increase subsequent pain, with higher self-efficacy and internal locus of control weakening this positive effect and higher fear of movement strengthening the association. Methods This prospective cohort study used ecological momentary assessment (EMA) over nine days. Fifty community-dwelling adults who had symptomatic knee OA consistent with American College of Rheumatology clinical criteria participated. Exclusion criteria included other forms of arthritis, neurological conditions, active cancer treatment, non-nociceptive pain, or lack of a compatible smartphone for EMA.Participants reported knee pain intensity, duration, and analgesic use four times daily using an EMA approach, via scheduled prompts delivered using a smartphone application (m-Path). Participant could also initiate prompts, unscheduled, to report pain flares. A pain composite score was calculated using z-score standardization of pain intensity and duration with participant-specific means and standard deviations, providing a novel within-person approach to characterizing knee OA pain. PA was continuously tracked using accelerometers (Actigraph wGT3X-BT) during waking hours. Psychosocial factors including fear of movement, self-efficacy, and locus of control were assessed through validated questionnaires at baseline. The primary objective examined whether the pain composite score influenced subsequent step count in the 90 minutes after EMA prompts, and whether this association was moderated by psychosocial factors (fear of movement, self-efficacy, locus of control). Generalized linear mixed models with Tweedie distributions and random intercepts examined these relationships, adjusting for age, gender, analgesic use, study day, prompt number, and prompt type. The secondary objective examined whether step count in the 90 minutes before EMA prompts influenced subsequent pain intensity, and whether this association was moderated by the same psychosocial factors. Linear mixed-effects models with random intercepts examined these relationships, adjusting for the same covariates. Results Complete data were available for 49 participants (64.8±7.2 years, 77% women) (1 accelerometer failure). These 49 participants reported moderate pain (KOOS Pain: 65.3±15.6), high daily activity (mean 11,661 steps/day), and mixed pain patterns (92% experienced both constant and intermittent pain). Average EMA compliance was 90%, with participants completing an average of 32 prompts over the study period. Valid accelerometer data was available for 96.6% of monitoring days. Fear of movement moderated the association between within-person pain composite score and subsequent step count (β = -0.0144, 95% CI [-0.0277, -0.0010], p = 0.035). Individuals with higher fear of movement showed a 4.9% greater step reduction per 1-SD increase (3.4 points on a 24-point scale) in fear of movement score. Self-efficacy for pain management also moderated this association (β = 0.0059, 95% CI [0.0018, 0.0100], p = 0.005). Individuals with higher self-efficacy showed a 6.8% smaller step count reduction per 1-SD increase (11.9 points on a 50-point scale) in self-efficacy score. Locus of control showed no moderation effect. In the reverse temporal direction, internal locus of control demonstrated a weak positive interaction with within-person step count on subsequent pain intensity (β = 0.000012, 95% CI [0.000002, 0.000022], p = 0.014). Individuals with higher internal locus of control experienced slightly greater pain intensity following higher step counts compared to those with lower internal locus of control. Self-efficacy for pain management demonstrated a significant main effect on subsequent pain intensity (β = -0.028740, 95% CI [-0.052042, -0.005439], p = 0.019). Individuals with higher self-efficacy reported lower pain intensity regardless of step count. Fear of movement showed no moderation or main effect. Discussion This study, using EMA and objective accelerometry, provides preliminary evidence that psychosocial factors moderate the temporal pain-PA relationship in adults with symptomatic knee OA. Those with higher self-efficacy for managing pain showed 6.8% smaller step reductions following greater pain; while those with higher fear of movement showed 4.9% greater reductions in step count after experiencing greater pain. In the reverse temporal direction, higher step counts were associated with increased subsequent pain intensity. Internal locus of control statistically moderated this association, though the interaction was very small and of uncertain clinical significance. Real-time assessment captured substantial within-person variability in pain and physical activity, including participant-initiated reporting of pain flares (77.6% of participants). The small interactions likely reflect considerable heterogeneity due to unmeasured contextual environmental factors. These findings suggest that self-efficacy, fear of movement, and locus of control may influence how individuals with knee OA respond to pain in daily life. While larger and more diverse samples are needed to establish clinical significance, these results suggest that self-management interventions targeting these factors and personalized pacing strategies during pain-free periods may help individuals with knee OA maintain activity despite pain fluctuations.
Spatial Ecology and Abundance of Turtles in Grundy Lake Provincial Park
(University of Waterloo, 2025-12-09) Ross, Mackenzie
Across the globe biodiversity is being lost at an unprecedented and unsustainable rate. The loss of biodiversity has direct and negative impacts on food production and other critical ecosystem services, to such a degree that we are currently experiencing a mass extinction event. Turtles are a group of vertebrates whose slow life histories and high juvenile mortality rates make them especially vulnerable to environmental changes. Anthropogenic climate change, habitat loss, and vehicle mortality are just a handful of factors responsible for an estimated 60% of turtle species being extinct or threatened with extinction. In Ontario there are currently eight native species of freshwater turtle, each are classified federally or provincially as at-risk species. Ontario represents the northern range periphery of these turtles presenting unique challenges including shorter active seasons and harsher winter weather. Grundy Lake Provincial Park is a protected area east of Georgian Bay Mnidoo Gamii in central Ontario. The three most common turtle species found in the park are the Blanding’s turtle, painted turtle and snapping turtle. Grundy Lake Provincial Park may be a stronghold for the globally endangered Blanding’s turtle, because of this in Chapter 2 we examined the spatial ecology of Blanding’s turtles at Grundy Lake Provincial Park by evaluating (1) habitat use, (2) home range and space use areas, (3), habitat selection, (4) minimum daily distance travelled, and (5) travel corridor identification. We found that both sex and behavioural season significantly impacted the spatial ecology of Blanding’s turtles, especially females during the nesting season. We identified travel corridors and areas of high-use in the park, highlighting areas important for habitat connectivity and nesting migrations. In Chapter 3, we examined population abundance and nesting distribution of all three species of freshwater turtle; our goal was to (1) estimate population abundance, (2) estimate somatic growth rate, (3) determine areas of high nest density, (4) evaluate carapace length distribution, and (5) estimate biomass and density. We estimated an abundance of 183 adult female painted turtles, 100 adult Blanding’s turtles and 63 adult female snapping turtles. Across species, somatic growth rate was greater in juveniles compared to adults. There was evidence of sexual size dimorphism in painted and Blanding’s turtles. Biomass and density estimates were highest for snapping turtles despite a low population estimate, emphasizing their role in the ecosystem. The turtle population in Grundy Lake Provincial Park represents an important stronghold near their northern range limit and offers a critical opportunity for long-term research in a protected area.
Classification Results for Intersective Polynomials With No Integral Roots
(University of Waterloo, 2025-12-08) Banks, Nicolas
In this thesis, we algebraically classify strongly intersective polynomials - polynomials with no integer roots but with a root modulo every positive integer - of degree 5--10. In particular, we compute a list of possible Galois groups of such polynomials. We also prove constraints on the splitting behaviour of ramified primes (i.e. primes that ramify in a splitting field of the polynomial). In the process, we show that intersectivity can be thought of as a property of a Galois number field, together with its set of subfields of specified degrees. This was achieved with characterisations of Berend-Bilu and Sonn, the latter of which we also generalise. Implementations in SageMath and GAP are provided. We also utilise Hensel's Lemma and other standard results on the local behaviour of simple field extensions.
Hardware-Assisted Defenses for Data Integrity and Confidentiality
(University of Waterloo, 2025-12-08) ElAtali, Hossam
The increasing complexity of modern computing systems and their exposure to the internet expose sensitive data to a range of security threats from remote adversaries. Bugs in software can lead to run-time attacks that gain direct access to sensitive data in memory, compromising its integrity and confidentiality. Furthermore, hardware and/or compiler optimizations can introduce data-dependent behavior that expose sensitive data to side-channel leakage, even in the absence of software bugs, breaking confidentiality. As business needs evolve, different usage scenarios, such as outsourced computation, have gained popularity, making the task of protecting data integrity and confidentiality more complex. This dissertation investigates how the integrity and confidentiality of sensitive data at run-time can be efficiently preserved through hardware-assisted mechanisms. I consider a range of usage scenarios and threat models, from protecting data sent to remote servers for outsourced computation by untrusted code, to protecting data processed locally from other vulnerable or malicious parts of the system. Specifically, this dissertation addresses: 1. how to efficiently protect data confidentiality against side-channel leakage with negligible overheads. Existing solutions to side-channel leakage suffer from significant overheads, making their deployment difficult in situations where performance is critical. I address this problem with CacheSquash, a software-transparent hardware mechanism to effectively harden against transient side-channel attacks such as Spectre and Meltdown with near-zero overheads. 2. How to combine protections against both direct access and side channels. I propose BliMe, a novel architecture that relies on remote attestation, taint-tracking and hardware-enforced data obliviousness to protect sensitive data processed by untrusted code in an outsourced computation setting. 3. For integrity, I propose PBI, a novel hardware primitive that enables efficient memory protection for sandboxing and in-process isolation, thereby safeguarding both data confidentiality and integrity. 4. Finally, I address how to efficiently combine memory safety and side-channel protection mechanisms for data integrity and confidentiality. For this, I propose BLACKOUT, a hardware-software extension to CHERI that enforces data-oblivious computation on sensitive data, and inherits the memory safety properties of CHERI, all while introducing minimal overheads. The proposed solutions confirm that hardware-assisted mechanisms can indeed be used to efficiently protect data at run-time, both from direct access and side-channel leakage. I conclude my dissertation with promising directions for future work.
Evaluating Face Mask Efficiency on Children and Adults
(University of Waterloo, 2025-12-05) El Khayri, Hicham
Small infectious aerosols have been a major vector for the spread of diseases such as COVID-19 and influenza. During the recent global pandemic, masking played a key role in reducing airborne transmission, although significant variability has been noted in the ability of different mask types to limit pathogen-laden aerosol dispersion and inhalation. Moreover, there remain significant gaps in the literature regarding mask performance for children. The aim of this thesis is to characterize mask inward protection efficiency for both children and adults, and source control efficiency for children in the 0.2 μm to 1 μm particle size range. An approach based on the conservation of mass guided the experimental methodology used to estimate mask filtration characteristics. For all tested masks, the material filtration efficiency was measured to be at or near 100%, whereas fitted filtration efficiencies for both source control and personal protection were significantly lower. This disparity underscores the highly degrading effects of leakage from gaps at the mask-face interface. Inward protection efficiency of N95, KN95, and surgical masks donned regularly and using the tie and tuck method were estimated on a medium NIOSH adult head form. The tested N95 barrier provided the greatest protection, followed by the KN95 respirator, while the surgical masks offered the least protection. Use of the tie and tuck for surgical masks method yielded only a small, statistically insignificant improvement in inward protection compared to regularly worn variants. Incorporating results from broader literature, mean inward protection efficiency ranges of [67.9%,100%] and [12.5%,79.6%] were determined for the N95 and regularly worn surgical masks, respectively. Both inward protection and apparent filtration efficiencies of adult, modified adult, and child variants of the KN95, CA-N95, and surgical mask as well as the N95 respirator, were estimated on a child manikin. Results further underscore the critical importance of proper fit to mask performance. Child-sized respirators provided higher source control and personal protection compared to other barriers tested. In contrast, the adult-sized surgical mask, which exhibited a loose fit on the child manikin, demonstrated poor performance in both metrics due to the highly degrading effects of leakage. Overall, whenever both variants are available, adult-sized masks demonstrate markedly reduced fitted efficiencies on the child manikin relative to child-sized variants, attributed to larger gaps at the mask-face interface. Flow visualization of air exhaled through the tested barriers qualitatively corroborated these findings, revealing substantially reduced leakage for child-sized variants compared to adult-sized equivalents. Given the increased sensitivity of children to mask breathing resistance, pressure differentials measured across masks donned on the child head form provided relative indicators of breathability. Results demonstrated that masks with similar filtration efficiency can exhibit significant differences in breathability. For example, the child-sized CA-N95 achieved equal or greater fitted filtration efficiency while consistently maintaining lower pressure drops compared to the child KN95. In fact, KN95 respirators showed differential pressures greater than or equal to those of all other tested masks. For a given mask type, better fit was associated with higher differential pressures. However, across different mask designs, higher filtration efficiency did not necessarily compromise breathability.
FROM THE MOUTHS OF HUNTERS: HUNTER PERCEPTIONS IMPROVE UNDERSTANDING OF THE RELATIONSHIP BETWEEN HUNTERS AND CONSERVATION IN CANADA
(University of Waterloo, 2025-12-05) Basdeo, Maya
As a group of nature-based outdoor recreationists, hunters in Canada are not well understood, particularly in the context of their role in conservation. Hunters in Canada are not typically equated with being conservation actors, however there is a dearth of current academic literature that addresses the relationship between hunting and conservation in Canada and thus hunters may not accurately be represented within conservation circles. Collaboration between different groups of conservationists could be improved, and gaining a better understanding of how hunters perceive their place in conservation may contribute to greater unity around issues of conservation concern. The research question I explored was “Do hunters in Canada perceive they contribute to conservation, and if so, in what ways?”. I used an anonymous online questionnaire to survey hunters across Canada using Qualtrics as the survey tool. The survey link was distributed through six provincial and territorial hunting-conservation organizations affiliated with the Canadian Wildlife Federation: Ontario Federation of Anglers & Hunters, Manitoba Wildlife Federation, Saskatchewan Wildlife Federation, Alberta Wildlife Federation, B.C. Wildlife Federation, and Yukon Fish & Game Association. The survey consisted of 23 questions and was conducted over a six-week period in the fall of 2023. 4022 valid responses were received from every province and territory, with the majority from Ontario. Four key themes emerged from the survey results of hunters in Canada: hunters identified more strongly as conservationists than as hunters, hunters identified numerous ways in which they participate in and support conservation, hunters are political actors, and hunters can be allies for conservation. Focusing on hunter perceptions was a necessary first step in exploring the relationship between hunters and conservation in Canada. The breadth of these results highlight opportunities for further empirical research and the need for more research to be conducted in Canada on this topic.
Quantum Fields in Curved Spacetimes: From Detector Entanglement to Black Hole Thermodynamics
(University of Waterloo, 2025-12-05) Bhattacharya, Dyuman
This thesis presents two independent investigations into quantum field theory in curved spacetime. The first concerns relativistic quantum information, with a focus on entanglement harvesting and detector-based probes of quantum fields in curved spacetimes. The second addresses semiclassical aspects of black hole thermodynamics in AdS braneworld settings, incorporating the backreaction of quantum fields to all orders of perturbation theory, and extending previous studies of quantum black holes to include both charge and spin. In Part I, we study the entanglement of quantum fields in curved spacetime, using localized particle detectors interacting with a scalar field. We analyze scenarios involving both flat and curved backgrounds, including gravitational shock waves, the BTZ black hole, and general dimensional anti–de Sitter and de Sitter spacetimes. For the case of initially entangled detectors, we find that interactions with the field can lead to either degradation or amplification of entanglement, depending on the initial state and spacetime geometry. We further derive exact expressions for density matrix elements, at the lowest perturbative order, in the form of infinite analytical series, for detectors on static worldlines in various spacetimes. The transition rate of an in-falling detector in the BTZ black hole spacetime is also derived as an infinite series. These analytic results allow for exact evaluation of quantities, namely the entanglement measures of concurrence and negativity, which are typically computed numerically. In addition, we provide a new example of the ability of detectors to distinguish topologically distinct spacetimes which are locally identical outside of horizons, focusing on the ℝP² and Swedish geons built from the BTZ spacetime. Our results show that localized measurements are sensitive not only to curvature but also to topological features of the underlying geometry. Part II is concerned with the construction and thermodynamic analysis of quantum-corrected black holes in a doubly holographic braneworld model. We obtain a charged and rotating solution localized on an AdS₃ brane embedded in an AdS₄ bulk, incorporating the full backreaction from conformal fields to all orders of perturbation theory. We compute the thermodynamic properties of these black holes, and examine their behavior in extended thermodynamic phase space where the cosmological constant is a variable. We find that the inclusion of charge or spin removes re-entrant phase transitions present in the neutral-static case, and that the critical exponents of these objects match those predicted by classical mean-field theory. The re-entrant phase transitions of the neutral-static quantum black hole has critical exponents which differ from the mean-field values
Woodland ecosystem services of the past and present in Herstmonceux and South England
(University of Waterloo, 2025-12-05) Pita, Katie
This thesis quantifies ecosystem services from broad- and mixed-leaved woodlands in the southern United Kingdom. Synthesizing concepts and approaches from historical ecology, environmental history, community ecology, dendrological allometry, and punctuated equilibrium theory, this thesis illuminates the multifaceted ways in which woodlands provide ecosystem services that are valued by people in the UK, both socially and ecologically. A complex relationship between people and woodlands emerges through time, which can be understood directly via management decisions, but also more abstractly through the sentiments that people attach to trees. Both of these approaches carry normative implications about the value of particular woodland ecosystem services. While the values that guided past decisions in woodland management are not always explicit, archival maps and remotely sensed data can reveal the nature of land use changes that manifest over long periods of time, i.e., 150 years. Within a case study context in Herstmonceux, East Sussex, archival data demonstrated a progression towards a modern day multifunctional wooded landscape. Within this modern context, historical woodland management regimes like coppicing drive specific ecosystem services like biodiversity and carbon storage to change measurably on a near-annual basis. This indicates that historic management regimes have important implications for ecosystem service provision not just over the course of generations, but also on fairly short time frames, e.g., 15 years. Land managers of coppice woodlands must therefore be cognizant of how everyday land management decisions can impact the ecosystem services, and therefore values (both intrinsic and instrumental) derived from them. Importantly, land management decisions and regimes also change abruptly in response to exogenous factors. When extreme damage was caused to trees and woodlands as a result of the October 1987 Great Storm, there occurred a traceable punctuation reflected in both the public sentiment and the priorities of woodland managers regarding trees. Changes in woodland ecosystem services can thus be slow-moving or sudden. Ultimately, it is this complex, always-changing relationship between humans and the environment that shape not only the actual provision of ecosystem services, but also perceptions of that provision, and, furthermore, how ecosystem services themselves are valued. The ecosystem services perspective, therefore, may be applied to and represent both intrinsic and instrumental values, rather than solely instrumental values, which has been a longstanding critique of the framework. However, researchers aiming to employ the ecosystem services framework in this manner must be intentional and explicit in their doing so, in order to shift the guiding paradigms in conservation away from “nature for people,” and towards a “people are nature” perspective.
Making Political Party Leaders: The Practice of Political Leadership in Canadian Party Leadership Races
(University of Waterloo, 2025-12-04) Columb, Conor Donnie
Party leaders are central to the Canadian party system because they represent their political parties at the national level, hold significant power within them over policy and messaging, and they often go on to form government following elections. Although scholars have studied leadership selection methods, party organization, and political campaigning, less attention has been paid to how aspiring party leaders develop political leadership in their respective campaigns. This gap invites the following questions: (1) how is political leadership constructed and communicated by aspiring leaders in Canadian political party leadership races; and (2) what campaign strategies do they most commonly use to present themselves as viable party leaders to party members? This study examined 16 candidates across three federal leadership races: the Liberal Party (2013); the New Democratic Party (NDP) (2017); and the Conservative Party of Canada (CPC) (2022). Through a qualitative content analysis of the campaign materials of each candidate in these races, such as media coverage, debate performances, and websites, this study identified the ways that candidates construct and communicate political leadership through their campaigns to persuade party members to vote for them as the party leader. Overall, this study further contextualized how leadership is marketed and performed in party politics.

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