UWSpace

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Recent Submissions

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    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.
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    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.
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    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.
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    Effects of natural Lithium and Lithium isotopes on voltage gated sodium channel activity in SH-SY5Y and IPSC derived cortical neurons
    (Springer Nature, 2025-08-07) Bukhteeva, Irina; Livingstone, James D.; Singh, Kartar; Pavlov, Evgeny V.; Beazely, Michael A.; Gingras, Michel J. P.; Leonenko, Zoya
    Although lithium (Li) is a widely used treatment for bipolar disorder, its exact mechanisms of action remain elusive. Research has shown that the two stable Li isotopes, which differ in their mass and nuclear spin, can induce distinct effects in both in vivo and in vitro studies. Since sodium (Na+) channels are the primary pathway for Li+ entry into cells, we examined how Li+ affects the current of Na+ channels using whole-cell patch-clamp techniques on SH-SY5Y neuroblastoma cells and human iPSCderived cortical neurons. Our findings indicate that mammalian Na+ channels in both neuronal models studied here display no selectivity between Na+ and Li+, unlike previously reported bacterial Na+ channels. We observed differences between the two neuronal models in three measured parameters ( Vhalf , Gmax, z). We saw no statistically significant differences between any ions in SH-SY5Y cells, but small differences in the half-maximum activation potential ( Vhalf ) between Na+ and 6Li+ and between 7Li+ and 6Li+ were found in iPSC-derived cortical neurons. Although Na+ channels are widely expressed and important in neuronal function, the very small differences observed in this work suggest that Li+ regulation through Na+ channels is likely not the primary mechanism underlying Li+ isotope differentiation.
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    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.