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    Structured Wavefunctions for Precision Quantum Metrology
    (University of Waterloo, 2025-10-20) Kapahi, Connor
    In this thesis, several projects from biomedical optics measurements of the retina to precision gravimetric designs with neutron interferometers are presented, united by the common theme of applied quantum information techniques to develop next-generation precision metrological instruments. In particular, we introduce theoretical tools for analyzing neutron optical experiments and highlight parallels between neutron and light optics. These tools are applied to a new neutron prism design, demonstrating significantly higher transmission than traditional designs. Designs for devices applying these techniques, including a neutron Fresnel prism, spectrum analyzer, and spin collimator, are discussed. Potential advantages in neutron flux and spectrum resolution are quantified for these designs. The isometry between neutron spin and the polarization of light is exploited to validate the neutron spin collimator experimentally. Applications of structured states of light and experiments applying spin-orbit states to create patterns in the human visual system are described. Results demonstrate an increase in the perceived extent of these patterns, from 3° for Haidinger's Brush to 10° for a spin-orbit state. Work demonstrating a new method of generating a lattice of spin-orbit states in light is applied to neutron optics. Throughout the preceding experiments, methods of modeling neutron optics experiments with light and a semi-classical path-integral approximation have been developed. These methods are then applied to design an experiment that measures the gravitational constant using a neutron interferometer. A three-phase grating moiré interferometer (3-PGMI) design is first tested with infrared light. The deflection caused by a wafer sample is measured with the 3-PGMI and found to match direct measurements. The path-integral model is then applied to determine the uncertainty in the gravitational constant that can be achieved with a near-term measurement with a neutron 3-PGMI. An experiment to measure the gravitational constant is described, with an uncertainty budget, resulting in a measurement to 150 ppm. Potential corrections to previous experiments measuring the gravitational constant, due to lunar gravitational forces are quantified. Future applications of the tools and techniques described in this thesis are then discussed.
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    Design, Synthesis, and Characterization of Multimetallic Complexes Supported by an Imidazopyrimidine-Based Trinucleating Ligand
    (University of Waterloo, 2025-10-17) Woods, Riley
    Transition metal catalysis has revolutionized chemical synthesis for decades and has allowed for the development of several Nobel prize-winning chemical reactions and processes. These catalysts, however, usually rely on the use of rare Earth metals such as platinum-group metals, mainly palladium, leading to economic and sustainability concerns. Recent studies on the use of Earth-abundant elements nickel, cobalt, and copper have revealed that these metals have the potential of offering low-cost alternatives to the traditional catalysts. Furthermore, these metals can access many more states, allowing for new and complementary reactivities to be achieved. Whilst transition metal catalysis is a large and impactful field, the majority of known catalysts are monometallic in nature. A compelling yet much underexplored area is the use of multimetallic complexes. Several studies and reviews have highlighted the beneficial effect of having multiple metal centers held in proximity. These sorts of systems often display improved catalytic performances over their monometallic counterparts. Synergy or metal-metal cooperativity between the centers is usually responsible for these observations, sometimes allowing for multielectron processes that are simply not possible with traditional monometallic catalysts. In terms of trimetallics, there is a paucity of ligand systems that can reliably produce a precise and controlled arrangement of the three metal centers in a way that is useful in catalysis. This is due to most relying on flexible organic frameworks tied to a symmetric node, additionally excluding them from heterometallic applications. Herein is reported a new trinucleating ligand framework, bpipp, specifically designed to enforce close proximity among three metal centers upon complexation. Based on the inherently unsymmetric imidazopyridmine backbone, the ligand features a tridentate pincer-like binding pocket with two additional bidentate binding pockets. This approach utilizes scalable synthetic methods to create a rigid ligand scaffold that precisely controls the spatial arrangement of the metals. The versatility of this ligand is demonstrated through the synthesis of several trimetallic complexes of Ni(II), Cu(II), Co(II); fully characterized by NMR spectroscopy, ESI-HRMS, and X ray crystallography. Notably, our ligand design achieves remarkably short metal-metal distances ranging from 3.3–3.5 Å, significantly closer than most reported trimetallic systems. This structural feature establishes an ideal platform for investigating genuine three-metal cooperative effects in catalysis.
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    Socioeconomic Indicators and Psychopathology in Children with Chronic Physical Illness
    (University of Waterloo, 2025-10-15) Khaira, Jothi
    Background: Children with a chronic physical illness (CPI) have an increased risk of developing psychopathology. The combination of chronic stress and socioeconomic disadvantage often contributes to poor mental health in this vulnerable population of children. Research Questions: This study addresses the following questions: (1) Are neighborhood-level socioeconomic indicators worse among families of children with CPI compared to the general population? (2) Are these socioeconomic indicators associated with psychopathology among children with CPI over a 48-month period? (3) Does child stress moderate associations between socioeconomic indicators and child psychopathology over time? Methods: Data come from the Multimorbidity in Children and Youth across the Life-course (MY LIFE) study, which followed 263 children aged 2-16 years who had been diagnosed with a CPI, for 48 months. A one-sample t-test compared mean differences in socioeconomic indices, measured by the Ontario Marginalization Index (ON-MARG), between MY LIFE and the general population. Linear mixed models (LMMs) examined associations between ON-MARG dimensions and psychopathology symptoms, as measured with the Emotional Behavioural Scales. Moderation by child HCC was investigated using a time-varying product-term interaction. Results: At baseline, the study included 263 children with a CPI (mean age: 9.4 years, 53% male). Children in MY LIFE resided in areas characterized by greater socioeconomic disadvantage relative to the general population (M= -0.38- -0.20, p= <0.001). Material resources (β=0.13, p=0.03) and the two-way interaction between households and dwellings and time (β=0.02, p=0.04) were significantly associated with parent-reported externalizing symptoms. Households and dwellings (β=0.09, p=0.02) and the three-way interaction between age and labour force, time, and child stress (β=0.02, p=0.04) were significantly associated with child-reported externalizing symptoms. No significant associations were noted between ON-MARG dimensions and parent- and child-reported internalizing symptoms. Conclusion: Children with CPI were more likely to live in areas of high socioeconomic disadvantage with housing and material deprivation predicting elevated psychopathology symptoms. LMMs showed that time-varying child stress may have a moderating effect on indicators of socioeconomic disadvantage, particularly related to households and dwellings and material resources. Differences between parent- and child-reported models reinforce the importance of multi-informant perspectives. Findings highlight the need for integrated, equity-informed interventions targeting both socioeconomic and physiological drivers of child psychopathology among children with CPI.
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    Automating Construction Material Sourcing and Distribution for Circularity
    (University of Waterloo, 2025-09-23) Olumo, Adama
    Circularity in the construction industry is developing, with increasing emphasis on extracting resources from existing infrastructure. Given the growing amount of resources embedded in the current housing stock, sustainability within the industry is critical. To support the large-scale reuse of Reclaimed Construction Materials (RCMs), through active reuse strategies, it is essential to develop tools and frameworks for sourcing RCMs. This study contributes to that effort by providing insights into the creation of such frameworks and emphasizing the value of material reuse within the construction sector. Although material reuse is considered an excellent circular strategy, the application of reuse across the industry still faces technical, social, and environmental limitations. A significant drawback of material reuse is the complexity of finding RCMs that fit a design with limited alterations required for use. Furthermore, the environmental and economic cost of acquiring and reusing RCMs is taxing, compared to acquiring New Construction Materials (NCMs). Additionally, there is limited insight into other options for restoring existing building resources before replacement. Therefore, this thesis develops decision support frameworks for component level assessment of RCMs and assembly level assessment of RCMs. The component level assessment tool is designed to integrate 3D scanning, Optimization Programming Languages (OPL), Life Cycle Assessment (LCA) and Building Information Modeling (BIM) tools to create an enhanced digital supply sourcing system; whereby RCMs at secondary sources can be found with basic required information like; cost, proximity and dimensions to enable planning and implementation. The component-level assessment framework is refined and extended through a policy assessment study, demonstrating its adaptability to diverse challenges presenting both risks and potential benefits for policy implementation. This thesis is fundamentally based on real-world data gathered from RCM stores and it challenges the current ongoing building design practices that deem material reuse as a problematic approach by enabling flexible sourcing of used and new building materials and providing an assessment framework for selecting appropriate restoration strategies. The approach alters the social perspective to consider partial integration of RCMs at varying levels of integration in new building projects.
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    Methods for Modelling Wetlands in Hydrologic Models
    (University of Waterloo, 2025-09-22) Tucker, Madeline Gabriela
    Wetlands are abundant natural systems that serve as important ecosystems, mechanisms for nutrient filtering and storage, and providers of flood mitigation services. Wetlands strongly influence the hydrologic response and water balance on a landscape. The practice of water resources management often relies on numerical computer models that represent hydrologic features within a watershed like wetlands, lakes, and rivers, to accurately simulate the movement of water. However, representation of wetlands in hydrologic models is challenged by their small-scale nature, numerous classification schemes that are not readily associated with a water balance conceptual model, and sometimes complex hydrology. A shortcoming of existing wetland modelling studies includes the lack of multiple wetland types being represented, often due to the complexity that accompanies wetland classification schemes. In this study, we address three research objectives: 1) to inventory existing wetland modelling methods and develop a catalogue of conceptual-numerical wetland modelling methods in hydrology based on wetland classifications and numerical water balance equations, 2) to implement conceptual-numerical wetland modelling methods in a regional hydrologic model case study and evaluate model performance to determine the impact of wetlands on simulation results, and 3) to examine how available wetland mapping products can inform wetland modelling. A hydrologic model of the Nipissing watershed in Ontario was built using the Raven Hydrologic Framework and calibrated in a multi-objective calibration to both high and low flow objective functions in three modelling scenarios. The first modelling scenario (Scenario 1) contained no wetland representation; the second modelling scenario (Scenario 2) contained explicit wetland representation of one wetland conceptual-numerical model type; and the third modelling scenario contained explicit wetland representation of three wetland conceptual-numerical model types based on connectivity of wetlands to modelled streams and lakes. Calibration results indicated good model performance for all model scenarios, as an adequate performance threshold of 0.50 for the Kling Gupta Efficiency (KGE) and log transformed Nash Sutcliffe Efficiency (logNSE) was achieved for both performance metrics. In calibration, Scenario 2 most often outperformed Scenario 1 (no wetland scenario) at individual calibration gauges and Scenario 3 (most complex wetland scenario) due to pareto solution uncertainty and site-specific properties. Validation results indicated that Scenario 3 most often outperformed the other two scenarios across multiple performance metrics at individual flow gauges and handled low flows especially well when analyzing low flow performance metrics and hydrographs. This is attributed to Scenario 3 storing the most water in wetland depressions out of all modelling scenarios from abstraction, lateral diversion of water accounting for wetland contributing areas, and groundwater process parameters set up for each simulated wetland type. Percent bias median and spread across all flow gauges significantly decreased by 15% from Scenario 2 to Scenario 3, highlighting the importance of low flow accuracy to hydrologic model performance. Flow duration curves and hydrographs plotted by flow gauge demonstrated that site-specific properties of the entire study area and individual gauge drainage areas can impact simulation results. There was no relationship found between gauge drainage area, wetland coverage percent by area, and model performance at individual gauges in this study. Four wetland mapping datasets in Ontario were compared to select a wetland data input to the Nipissing model. By comparing each wetland dataset, a formalized checklist is provided for modellers to use as a reference when making similar comparisons between their own wetland mapping products. It is recommended that wetland mapping product comparisons for project suitability be performed by first comparing wetland coverage between datasets using the wetland polygon coverage by area, then comparing spatial variability between datasets by inspecting areas of overlap and non-overlap, and finally comparing data attributes, particularly wetland classifications and any discrepancies between dataset attributes. While the results of this study demonstrate the importance of low flow accuracy to model performance through the representation of wetlands, improvements could be made to aid future studies. It is recommended that future studies select a watershed with high quality flow and meteorological data, basins with varying wetland coverage, and little to no water regulation influence (e.g., hydroelectric dams). It is also recommended that the wetland conceptual-numerical models presented in this thesis be further tested on watersheds of different sizes, different combinations of wetland types, and varying degrees of complexity.