PRISM | Institutional Repository
Communities in PRISM
Select a community to browse its collections.
Recent Submissions
Item type: Item , Access status: Open Access , Strategies for Powerful Quantum-Enabled Bitcoin Miners(2026-01-09) Manson, Zachary Allan; Sanders, Barry Cyril; Oblak, Daniel; Safavi-Naeni, Reyhaneh Alsadat; Hobill, David WesleyBitcoin miners equipped with purpose-built quantum computers that execute Grover’s algorithm on classical candidate blocks, measuring the resulting quantum state to yield a potentially valid proof-of-work, pose a threat to Bitcoin’s security against 51% attacks. I aim to assess this threat by employing a game-theoretic framework inspired by the Lee-Ray-Santha quantum races model, extending it to better reflect how quantum miners would behave in practice. These extensions address some of the simplifications of prior works, where quantum miners performed only one quantum measurement (which does not maximise their resources), and were assumed to employ a peaceful strategy, wherein the quantum miners discard the resources already invested into searching upon receiving a broadcast of a newly-mined block (which is not enforceable). I consider a setting in which the quantum miners perform multiple quantum measurements between successive blocks, employ Sattath’s Aggressive Quantum Mining Strategy (AQMS), and must allocate limited quantum resources across these measurements. When employing Sattah’s AQMS, a quantum miner halts their execution of Grover’s algorithm and measures the resulting quantum state upon receiving a broadcast of a newly mined block, attempting to create a temporary fork and thereby decreasing the effective hash rate required for a 51% attack. In this novel setting, I derive the payoff matrices for the quantum miners and compute optimal quantum mining strategies that correspond to Nash equilibria. I simulate the deployment of these optimal quantum mining strategies within the Bitcoin network and estimate their effect on Bitcoin’s security against a 51% attack. I determine how two quantum miners should optimally allocate their quantum resources based on the network difficulty. Overall, I find that even when behaving optimally, two quantum miners cannot create enough temporary forks to render the Bitcoin network vulnerable to this quantum threat, given realistic constraints on their quantum resources. This thesis contributes to the growing body of research on the potential threats posed by scalable quantum computers, using the case of two quantum miners as a step toward understanding how quantum miners in general could affect Proof-of-Work-based cryptocurrencies like Bitcoin.Item type: Item , Access status: Open Access , An Ultra-Wideband-Based Indoor Ranging and Positioning System with Wireless Synchronized Beacons Networks for Asynchronized Receivers(2026-01-16) Cao, Ying Xuan; Fapojuwo, Abraham; Dehghanian, Vahid; Fapojuwo, Abraham; Dehghanian, Vahid; O'Keefe, Kyle; Ghannouchi, FadhelThis thesis designs and studies an Ultra-Wideband (UWB)-based radio frequency (RF) infrastructure aimed at accurate ranging and positioning in GNSS-denied environments such as tunnels and other indoor facilities. This study evaluates the performance and reliability of UWB ranging technology in multipath-rich environments with Line-of-Sight (LOS) path clear, LOS path weak, and LOS path blocked conditions between two modules. The thesis proposes a novel Leading and Secondary beacons – Time Difference of Arrival (LS-TDOA) method for beacon-based positioning systems to eliminate synchronization requirements between beacons and receivers while mitigating clock errors to achieve a good balance in the trade-off between device compatibility, deployment convenience, and positioning accuracy. The thesis details the proposed LS-TDOA algorithm, system-level design, UWB technology selection, wireless channel analysis, and hardware implementation. The thesis provides a comparative analysis of the LS-TDOA with Two-Way Ranging (TWR) and traditional Time Difference of Arrival (TDOA) methods and highlights its efficiency. Simulation and experimental results confirm the feasibility and accuracy of the LS-TDOA approach. Finally, the thesis provides some future work suggestions focusing on scalability and performance in complex environments.Item type: Item , Access status: Open Access , Physical activity, quality of life, and mental health amongst Canadian children and youth with disabilities(2026-01-08) Schnitman, Hannah; Emery, Carolyn; Latimer-Cheung, Amy; Condliffe, Elizabeth; St. John, Laura; McMorris, CarlyPhysical activity provides numerous health-related benefits across populations. Despite this, children and youth with disabilities (CYD, ages 5-24 years) face stigma, discrimination, and other barriers that exclude them from physical activity participation and negatively affect their mental health and quality of life. Fortunately, adapted physical activity camps/programs provide opportunities for CYD to be active in an inclusive environment. While much of the available literature examines the amount of physical activity required for benefits, a newer concept that has emerged is the quality of physical activity participation. Moreover, there is a lack of quantitative examination of factors influencing quality of life for CYD, along with exploring how physical activity experiences may shape mental health. To address these gaps, we conducted two research studies amongst Canadian CYD. The first study is a cross-sectional study in which we explored the associations between quality of life with demographic characteristics (e.g., age, sex, impairment type), quantity of physical activity, and quality of physical activity. Our sample included 51 CYD and we demonstrate an association between having a physical impairment and reporting more quality of life problems. CYD who reported having a positive physical activity participation experience also report fewer quality of life problems. We found no associations between quality of life and sex, age, nor amount of physical activity. The second study (chapter 4) was a qualitative exploration including 12 youth with disabilities (ages 15-24 years) to discuss how their physical activity participation has shaped their mental health. Mental health was largely influenced by connection: connection to a fellowship within adapted programs, connections to realizing their capabilities and developing their confidence and competence, and connections to their emotional regulation and resilience. Each of these interconnected subthemes played a critical role in promoting many aspects of their mental health (e.g., relieving stress, promoting self-efficacy). In conclusion, physical activity experiences appeared to play a significant role not only on quality of life, but also specifically on shaping mental health. Future research should continue to explore ways to improve participation experiences amongst CYD so that they may reap the benefits of physical activity throughout their lives.Item type: Item , Access status: Open Access , Air-Sea CO2 Exchange and Carbon Dynamics in Foxe Basin: Findings from a 2023 Oceanographic Survey(2026-01-14) Purdon, Cassandra Charlotte; Else, Brent; Tutolo, Benjamin; Yackel, JohnThe ocean plays an important role in climate by removing large amounts of carbon dioxide (CO2) from the atmosphere through air-sea gas exchange. This process is particularly important in polar oceans, where sea-ice formation releases brine to the water column below and can create dense waters that sink and sequester dissolved carbon into deep waters. Foxe Basin, an inland sea north of Hudson Bay between Baffin Island and Melville Peninsula, is an ideal location to study this process as it is one of the few known places in Canada where sea-ice-driven deep water formation occurs consistently. A synoptic survey took place in Foxe Basin aboard the research icebreaker CCGS Amundsen in October 2023. Findings indicate that Foxe Basin was a weak sink for atmospheric CO2 during fall with a mean pCO2 of 396 ± 19 µatm and air-sea CO2 flux (FCO2) of -1.9 ± 2.1 mmol m⁻² day⁻¹. High pCO2 and positive FCO2 were associated with water column mixing and upwelling along the shelf break and Foxe Peninsula, while high pCO2 near Hall Beach reflected meteoric water input. Deep water bearing the signature of sea-ice brine formation (high salinity, low temperatures) and enriched in dissolved inorganic carbon (DIC) and total alkalinity (TA) was observed in Foxe Channel. A carbon budget attributed the 160 µmol kg⁻¹ enrichment in DIC between the surface and deep water to brine rejection (72%), respiration (24%), and gas exchange (4%). TA:DIC ratios showed no evidence that ikaite retention in sea ice affected bottom water carbonate chemistry. This thesis provides some of the first estimates of CO2 concentrations and carbon export in Foxe Basin, offering exciting insights into Arctic carbon cycling. This work highlights that sea-ice processes in Foxe Basin are particularly important for carbon export to deep water, making Foxe Basin an ideal location to study the role of sea ice in carbon export. These findings establish a foundation for future research necessary to achieve a comprehensive understanding of the basin's carbon dynamics.Item type: Item , Access status: Embargo , Evaluating Care Complexity in Inflammatory Arthritis – A Population-Based Approach using CART Analysis to Examine Healthcare Utilization(2026-01-09) Sipley, Melissa; Barber, Claire; Aquino, Camila; Holodinsky, Jessalyn; Crump, TraffordAutoimmune inflammatory arthritis is one of the most prevalent chronic health conditions in Canada, affecting approximately 3% of the population. Common inflammatory arthritis conditions include rheumatoid arthritis (RA), psoriatic arthritis (PsA), and ankylosing spondylitis (AS). Individuals with inflammatory arthritis often experience high care complexity, characterized by multiple comorbidities, polypharmacy, social factors, and diverse healthcare needs, which can influence patterns of healthcare utilization. The aim of this study is to identify care complexity factors predictive of high healthcare utilization, including physician and emergency department (ED) visits, among adults with inflammatory arthritis in Alberta. We identified individuals diagnosed with RA, PsA, or AS using a validated administrative case definition. Sociodemographic and disease-related factors contributing to care complexity were described for each cohort, including age, sex, place of residence, socioeconomic status (SES), comorbidities, disease type, medication use, and opioid and glucocorticoid dispensations. Classification and regression tree (CART) models were developed to identify combinations of these care complexity characteristics that were predictive of high healthcare utilization. The study included 13,170 individuals. Care complexity varied across disease cohorts: older age, rural residence, multimorbidity, and glucocorticoid use were most common among people with RA; low SES was most prevalent in PsA; and opioid use was highest in AS. Polypharmacy, the presence of anxiety, older age, urban residence, and having PsA were predictive of high physician visits while polypharmacy, rural residence, and having RA or AS were predictive of high ED visits. These findings highlight distinct patterns of healthcare utilization driven by specific care complexity factors, offering insight into patient stratification and potential targets for interventions to optimize care delivery in inflammatory arthritis. However, the models were not fully able to capture or predict all aspects of complexity, underscoring the need for additional data and/or methods to more fully understand care complexity in inflammatory arthritis. Advancing this work could lead to more accurate prediction, better personalized care, and ultimately, improved health outcomes.
