Faculty of Graduate Studies Online Theses
Permanent URI for this collectionhttps://hdl.handle.net/10222/11163
Browse
Recent Submissions
Item Open Access HYDROGEN PERMEATION AND EMBRITTLEMENT IN PIPELINE STEELS AND NICKEL-BASED ALLOYS: A COMPARATIVE STUDY IN SIMULATED ALKALINE ENVIRONMENTS(2025-07-18) Sey, Emmanuel; Not Applicable; Master of Applied Science; Department of Mechanical Engineering; Not Applicable; n/a; Yes; George Jarjoura; Hamid Afshari; Zoheir FarhatThe growing global demand for natural gas as a primary energy source, particularly in industrial sectors such as power generation, petrochemical processing, and manufacturing, has driven the need to explore cleaner, more sustainable alternatives. Though it plays a vital role in meeting energy needs due to its high energy content and reliability, its combustion results in greenhouse gas (GHG) emissions, especially carbon dioxide (CO₂), which contributes significantly to climate change. One promising approach is blending natural gas with hydrogen, as hydrogen burns cleanly without releasing harmful emissions. However, this introduces a new materials challenge: the potential for hydrogen embrittlement (HE) in metallic pipelines used to transport natural gas. This study evaluates the mechanical performance of pipeline steels and Nickel based alloys under tensile and fatigue loading conditions, both before and after electrochemical hydrogen charging in a simulated alkaline environment. The results showed material-specific responses to hydrogen ingress, with distinct degradation patterns observed through fracture surface analysis.Item Open Access The Vertical Street: Transforming Tower and Slab Urban Housing(2025-07-17) Kirkland, Erika; Not Applicable; Master of Architecture; School of Architecture; Not Applicable; n/a; Not Applicable; Diogo Burnay; Joyce Hwang; Niall SavageCurrent tower and slab urban housing often isolates residents from the public realm, creating a disconnect and diminishing community engagement. Conventional high-rise housing often lacks the interconnected public spaces and pedestrian-friendly qualities that define successful urban environments. This thesis aims to introduce the concept of a transformed tower and slab model by integrating the social vibrancy of traditional streets into the high-rise typology. A bridge between private and public spaces emerges by exploring how multi-path circulation, layered programming, and shared social spaces can transform sterile corridors and isolated towers into dynamic, interactive environments. The Vertical Street envisions a seamless blend of housing and ‘street’ interaction zones, activating shared spaces that support diverse programming and moments of spontaneous social engagement with the ultimate aim of demonstrating an alternative to conventional tower typologies, promoting inclusivity, community, and social interaction in high-density urban housing.Item Open Access SQL Protection Using Generative Modeling for Anomaly Detection(2025-07-17) Afrin, Sadia; Not Applicable; Master of Computer Science; Faculty of Computer Science; Not Applicable; n/a; Not Applicable; Vlado Keselj; Saurabh Dey; Nur Zincir-Heywood; Marwa A. ElsayedSQL injection (SQLi) exploits vulnerabilities in an application’s input validation logic to manipulate backend SQL queries, allowing attackers to bypass authentication, extract sensitive data, or corrupt databases. Despite decades of research and the emergence of modern web frameworks with built-in safeguards, SQLI remains on the OWASP Top 10 list, demonstrating its persistent relevance and evolving sophistication. While more research has been conducted on detecting traditional SQLi attacks, relatively less attention has been given to identifying adversarial variants designed to evade standard defenses. Traditional detection approaches, such as signature-based filtering and rule-based systems, fall short against novel or advanced adversarial SQLi attacks because they rely on predefined patterns that cannot generalize to unseen payloads. This thesis proposes an alternative approach by leveraging generative modeling for SQLi detection. The results suggest that generative models paired with Word2Vec embeddings show impressive performance.Item Embargo HUMANIZED MOUSE MODEL TO STUDY CYSTIC FIBROSIS-RELATED DIABETES(2025-07-17) Neira Agonh, Daniel; Not Applicable; Master of Science; Department of Physiology & Biophysics; Received; Christopher Sinal; Not Applicable; Ferhan Siddiqi; Alejandro Lomniczi; Valerie Chappe; Younes AniniUp to 50% of people with cystic fibrosis (CF) develop CF-related diabetes (CFRD), accelerating lung function decline and mortality, particularly among women. Our study validates the B6-Tg(CFTR508del)Cwr (hCF) mouse, expressing the human ΔF508del CFTR gene, to study CFRD. Glucose handling was assessed by oral (OGTT) and intraperitoneal glucose tolerance tests (IPGTT); insulin and glucagon levels were evaluated via ELISAs; and islet structure was analyzed by immunofluorescence. Following IPGTT, hCF mice showed glucose intolerance with higher glucose area under the curve than WT mice; OGTT showed progressive glucose intolerance. hCF mice exhibited low fasting insulin, impaired insulin secretion, and reduced islet insulin signal intensity. Glucagon levels were generally similar across experimental groups; however, pancreatic glucagon levels were elevated in hCF males. hCF pancreata contained fewer and smaller islets than WT pancreata. These results demonstrate features of CFRD within the hCF mouse model: glucose intolerance, insulin insufficiency, and impaired islet architecture.Item Open Access EMANCIPATE ME HARDER! LESSONS FROM THE BDSM COMMUNITY ON SAFETY, CONSENT, THERAPEUTIC POTENTIAL, AND RADICAL SUBVERSIVE RESISTANCE(2025-07-11) Rae, Madeline; Not Applicable; Master of Social Work; School of Social Work; Received; Dr. Elaine Brooks-Craig; Not Applicable; Dr. Neil McArthur; Dr. Raluca Bejan; Dr. Catherine BryanBDSM has developed as a recognized sexual sub-culture and has been the subject of considerable attention, notably by medical and psychiatric fields. Often pathologized, and even criminalized, the BDSM community’s self-definition differs greatly from those offered by early patriarchal psychoanalysts and contemporary mainstream institutions. A growing body of scholarship indicates that BDSM has therapeutic potential. The present study interviewed 6 professional practitioners of BDSM from across Canada. These professionals have practiced for over 10 years and have a well-established understanding of in-group best practices as well as the ongoing impacts of pathologization and discrimination. Over 15 hours of semi-structured interviews yielded findings that support that the S/M community remains misunderstood, misrepresented (in courts of law, mental health settings, and in media), that best practices and codes of conduct are taken extremely seriously, and that subversion largely contributes to BDSM’s cathartic, healing, and therapeutic potential.Item Open Access EXAMINING THE FEASIBILITY OF MINE THERMAL ENERGY STORAGE (MTES) IN NOVA SCOTIA: A CASE STUDY OF GLACE BAY(2025-07-14) Sohrabikhah, Sara; No; Master of Applied Science; Department of Electrical & Computer Engineering; Not Applicable; Dr. Trevor Kelly; No; Dr. Yuan Ma; Larry HughesMine Thermal Energy Storage (MTES) offers a promising solution for sustainable heating by repurposing abandoned, water-filled mines as underground thermal reser-voirs. This study assesses the feasibility of implementing MTES in Nova Scotia, with a focus on the Sydney Coalfield region, particularly Glace Bay. The research combines geological analysis, residential heat demand estimation, thermal storage capacity esti-mation, and cost-benefit evaluation to determine whether abandoned coal mines can support district heating applications. Results show that MTES can deliver substantial heating cost reductions compared to oil-based systems, while significantly lowering greenhouse gas emissions. The study also explores the integration of MTES with local renewable energy sources, including wind and solar, to enhance energy system flexi-bility and reliability. International case studies from Springhill (Canada), Heerlen (Netherlands), and Bochum (Germany) are analyzed to illustrate the scalability, per-formance, and operational challenges of MTES systems. Key technical barriers—such as water quality management, infrastructure investment, and seasonal variability in heat demand—are discussed. Overall, the findings highlight MTES as a viable and sustainable energy storage approach for Nova Scotia and other regions with legacy mining infrastructure.Item Open Access Synthesis and Characterization of Cationic Polyelectrolytes to Address Changing Source Water Quality(2025-07-09) Sun, Zhisen; Not Applicable; Master of Applied Science; Department of Process Engineering and Applied Science; Not Applicable; n/a; Not Applicable; Professor Khaled Benis; Professor Graham Gagnon; Professor Alison ScottThis research focuses on developing novel cationic flocculants (polyelectrolytes) for drinking water treatment. Cationic flocculants are currently used in many municipal water treatment processes, but are not able to effectively address changing source water quality challenges. These challenges include increased concentration of humic substances and more frequent algae bloom occurrences. Changes in source water quality generally require higher dosing of traditional coagulants and flocculants, which increases treatment cost and sludge production. Hence, this research investigates novel cationic flocculants to determine how comonomer selection and copolymer properties impact treatment performance. Nine cationic copolymers were synthesized and characterized according to copolymer conversion, molecular weight distribution, zeta potential, and jar testing. Of the materials evaluated, the most promising cationic flocculant was the copolymer of methacrylamide (MAA) and (p-vinylbenzyl)trimethylammonium chloride (VBTMAC), which shows great UV-254 results among other alternative cationic flocculants. These results demonstrate that utilities can adapt to changing source water quality through material innovation, instead of (or alongside) costly process innovation. Further optimization is still possible through future work, including manipulating the molar ratio of neutral monomer and cationic monomer, improving understanding of intermolecular interactions between target contaminants and promising cationic flocculants, and extending results to bio-derived polymer flocculants. Through an iterative design approach, novel cationic flocculants can be optimized for specific water treatment challenges.Item Open Access The Urban Quad: Reimagining Dalhousie Sexton Campus as an Open-Ended Landscape(2025-07-14) Tillmann, William; Not Applicable; Master of Architecture; School of Architecture; Not Applicable; Rashida NG; Not Applicable; Niall Savage; Roger MullinThis architectural thesis proposes the Urban quad as a new architectural type to mediate between Dalhousie University’s Sexton Campus and its host, the city of Halifax. Drawing from typological theory and Stan Allen’s field conditions, it develops a method that treats form as emergent from contextual pressures such as: social, environmental, and infrastructural. Strategies include deploying fields of material, reinterpreting precedent, daylighting and systematic and rhythmic ordering of walls, floors, roofs and columns. The design transforms a surface parking lot behind the Halifax Central Library into a shared academic and civic ground. It incorporates existing structures, notably Gerard Hall, while introducing new spaces: a public ramped landscape, interior atrium, and split-level commons. Represented through axonometric drawing, the outcome is a layered, porous framework that invites institutional and public life to overlap.Item Open Access The Development and Evaluation of Nature Matters: an Evidence-Informed Program for Increasing Nature-Focused Behaviours and Nature Connection in Undergraduate Students(2025-06-29) Ibrahim, Yasmeen; Not Applicable; Doctor of Philosophy; Department of Psychology and Neuroscience; Received; Dr. John Zelenski; Yes; Dr. Leanne Stevens; Dr. Alissa Pencer; Dr. Shannon JohnsonMental health difficulties and stressors are prevalent amongst undergraduate students, whereas resources to support students’ mental health are limited. The well-documented benefits of exposure to, and connection with, nature include various aspects of mental, physical, and cognitive health, yet many people are unaware of these benefits and do not engage with nature as a health behaviour. This dissertation describes the development and evaluation of Nature Matters, an online evidence-informed wellness program that integrates the behavior change wheel framework with evidence-based learning strategies to raise undergraduate students’ awareness of the benefits of exposure to nature and encourage behavior change. In Study 1 (N = 108), I assessed the usability and acceptability of Nature Matters using a mixed-methods design. Both quantitative and qualitative results indicated that the program was well-received by undergraduate students, with positive ratings attained for all user-experience domains (1. Perspicuity or clarity/ ease of understanding, 2. Stimulation, 3. Usefulness, 4. Attractiveness, 5. Visual Aesthetics, 6. Trustworthiness of Content, and 7. Quality of Content). In Study 2, I examined if completing Nature Matters 1) enhanced connectedness to nature, 2) increased frequency of exposure to nature; and 3) increased frequency of noticing nature. As hypothesized, participants who completed the program (n = 45) reported greater connectedness to nature and a higher frequency of exposure to nature compared to control participants (n = 46), after accounting for baseline scores. Results for noticing nature were not significant. Exploratory regression analyses revealed that lower baseline levels of nature connectedness, noticing nature, and exposure to nature were all associated with a larger change in post-program outcome scores. Overall, the findings demonstrate the acceptability and effectiveness of Nature Matters for an undergraduate population, suggesting that this program has potential as an intervention for increasing exposure to and connection with nature. Building upon this evidence will advance the utilization of the human-nature connection for improving well-being and pave the way for the development of similar wellness programs.Item Open Access Psychiatric Natural Kinds: Implications for Nosology, Practice, and Policymaking(2025-07-12) Andrews, Derek; Not Applicable; Doctor of Philosophy; Department of Philosophy; Not Applicable; Dr. Jonathan Tsou; Not Applicable; Dr. Tyler Hildebrand; Dr. Letitia Meynell; Dr. Kirstin BorgersonI seek to answer two main questions in this dissertation. First, what are mental disorders? Second, what are the implications for psychiatry and mental health policymaking? I propose that mental disorders are natural, mechanistic property cluster (MPC) kinds, underlain by one or more biological, psychological, and/or social mechanisms, with harmful effects for their bearers. Mental illnesses, on the other hand, are disease states that obtain when (1) a mental disorder obtains; (2) the bearer’s subjective experience of the disorder is a sufficiently significant impediment to their life; and (3) ascribing disease status to this individual case of mental disorder serves the legitimate strategic goals of enabling access to psychiatric care or other appropriate benefits and accommodations. I reach this conclusion by considering and rejecting a series of alternative proposals. Some alternatives fail to conform to our best scientific understanding of the etiologies of mental disorders, while others fail to accommodate all conditions of concern for psychiatry. My approach offers improvements to the accuracy of psychiatric nosology, diagnosis, and prognostication that other approaches to the metaphysics of kinds do not, while successfully accommodating the psychosocial dimension of the etiologies of mental disorders. My account achieves this by adopting a holistic naturalist perspective on mental disorders’ etiologies and a radical pluralism about disease state ascriptions, which allow it to accommodate the full range of entities of interest to psychiatry and provide a disease concept aligning with its use in psychiatry. My account also allows us to distinguish good from bad causal inferences made on the basis of membership in a psychiatric natural kind. This reveals when it is, and is not, appropriate to rely solely on general inferences about mental disorders. I argue that drawing such inferences is appropriate in contexts of psychiatric research and practice, but not in general policymaking. This is because doing so in the latter context requires reference to a broader range of epistemic resources, without which the resulting policies are epistemically and morally unjustified.Item Open Access COMPLEMENTATION OF GENOTYPE-TO-PHENOTYPE ANTIMICROBIAL RESISTANCE PREDICTION OF ENTEROCOCCI WITH EXPERIMENTAL APPROACHES(2025-07-13) KIM, JEE IN; Not Applicable; Doctor of Philosophy; Interdisciplinary PhD Programme; Not Applicable; Dr. David S. Guttman; Yes; Dr. Morgan Langille; Dr. John Rohde; Dr. Rob Beiko; Dr. Tim McAllisterAntimicrobial resistance (AMR) is a global-health crisis that currently causes more than 1 million deaths annually. Whole-genome sequencing (WGS) data can provide insights into AMR transmission and mechanisms to guide surveillance and prevention strategies. Machine learning (ML) has shown great promise in predicting resistance phenotypes from WGS data, but predictions must be rigorously examined and experimentally corroborated prior to clinical implementation. We used ML and feature selection to examine the key drivers of prediction accuracy in 647 genomes of Enterococcus faecium and Enterococcus faecalis for vancomycin, doxycycline, and erythromycin resistance. Known resistance genes were predictive of vancomycin and doxycycline resistance, but not erythromycin. Mobile genetic elements (MGEs) alone also yielded highly accurate predictions, highlighting their association with key resistance genes. We experimentally tested this linkage by quantifying rates of plasmid transfer among Enterococcus species. The vancomycin resistance gene-carrying MGEs existed as a transposable unit alone or nested within a plasmid. Conjugation was successful with all of the tested intra- and interspecies hosts. Doxycycline and erythromycin resistance genes were always transferred via a plasmid, with limited instances of interspecies conjugation. Transcriptome profiling of enterococci exposed to vancomycin or doxycycline revealed upregulation of key predictive drivers, including genes and MGEs, associated with resistance. Doxycycline demonstrated the highest number of differentially regulated genes encoding proteins involved in general stress response and metabolic adaptation, which the ML prediction models did not capture. In the case of erythromycin, the key resistance gene ermB was not differentially expressed, consistent with the established role of mutations in regulatory regions leading to its constitutive expression. Our study found that vancomycin and doxycycline resistance can be accurately predicted using AMR genes and MGEs, with MGEs posing a particular risk due to their conjugative capacity across different Enterococcus isolates. Accurate prediction of erythromycin and other resistance phenotypes may require additional features based on allelic variation and regulatory-sequence mutations that are not represented in the pan-genome profiling. Complementing ML prediction models with experimental results on the dissemination and expression of resistance determinants helps identify the most consistent and relevant features for model development, bringing ML technology closer to real-world implementation.Item Open Access TRAINING AND EVALUATING THE USE OF LARGE LANGUAGE MODELS (LLMS) IN THE DOMAIN OF CANADIAN NUCLEAR INDUSTRY(2025-07-10) Anwar, Muhammad Saleh; Not Applicable; Master of Science; Department of Engineering Mathematics & Internetworking; Not Applicable; N/A; Not Applicable; Dr. Guy Kember; Dr. Kamal El-Sankary; Dr. Issam HammadThis thesis addresses the challenges of accuracy, reliability, data privacy, and resource constraints in applying Large Language Models (LLMs) to the Canadian nuclear industry. It presents a multi-faceted approach by evaluating existing models, developing synthetic data generation techniques, and training a secure, domain-specific LLM from scratch. The research first demonstrates that while general-purpose LLMs are prone to factual inaccuracies on nuclear-specific topics, their reliability is significantly improved by integrating a Retrieval-Augmented Generation (RAG) framework. This approach enhances factual accuracy by grounding responses in verified, domain-specific documents. To overcome data scarcity and confidentiality barriers, the thesis pioneers a methodology for generating synthetic, structured question-and-answer pairs from unstructured nuclear texts using LLMs. This scalable and privacy-preserving approach creates valuable, model-ready datasets for training and evaluation without exposing sensitive information. Furthermore, the work validates the feasibility of developing a secure, private LLM from scratch. By training a compact model on a single GPU using the "Essential CANDU" textbook, it demonstrates a practical path for creating in-house models that mitigate cybersecurity risks and can learn specialized terminology within a resource-constrained and secure environment. Collectively, this research provides a comprehensive framework for integrating LLM technology safely and effectively into the nuclear industry, establishing a foundation for advanced AI tools that enhance knowledge management and operational support.Item Open Access Model Predictive Control for Autonomous Sailboat with Sail Angle Optimization and Trajectory Planning Under Stochastic Winds(2025-07-14) Wu, Junzhuo; Not Applicable; Master of Applied Science; Department of Mechanical Engineering; Not Applicable; N/A; Not Applicable; Dr. Baafour Nyantekyi-Kwakye; Dr. Hamed Aly; Dr. Ya-Jun Pan; Dr. Chao ShenThis thesis investigates the development and implementation of model predictive control (MPC) frameworks for autonomous sailboat control under different wind conditions. The research is motivated by the need for robust, constraint-aware control strategies for sailboats, that can effectively handle the nonlinear dynamics and environmental uncertainties. The study begins with a comprehensive modelling of sailboat dynamics, incorporating sailboat kinematic and kinetics and wave disturbances. Two simulation-based studies both using MPC are then conducted. The first study focuses on sail angle optimization and trajectory tracking, where the control objective is to maximize sailing speed with safety considerations and then achieve accurate trajectory tracking. The second study addresses stochastic wind sailing, where an NMPC-based path planning and tracking controller is designed and evaluated. This controller integrates the controllability analysis to improve performance under both deterministic and stochastic wind conditions. Comparative simulations highlight the advantages of the proposed approach. Then, an experimental platform is instrumented on a small-scale physical autonomous sailboat. This platform integrates the ArduPilot control stack, hardware components and supporting software infrastructure. System identification techniques are applied to extract sailboat’s dynamic model, and experimental trials are conducted to assess the controller performance in real-world conditions. The results demonstrate that MPC offers a viable and effective solution for autonomous sailboat control, capable of addressing both operational constraints and environmental variability.Item Open Access Beyond Monocular Vision: Assessing LLaVA's Performance on an Augmented CLEVR-like Dataset with Binocular Images(2025-07-07) Devesh, Sagar; Not Applicable; Master of Computer Science; Faculty of Computer Science; Not Applicable; n/a; Not Applicable; Vlado Keselj; Hassan Sajjad; Frank RudziczThis thesis investigates how binocular vision impacts the spatial reasoning capabilities of Large Language and Vision Assistant (LLaVA) models in visual question answering tasks. By developing BiCLEVR, an augmented CLEVR-like dataset featuring stereoscopic image pairs and expanded visual attributes, we systematically evaluate the effect of different visual inputs across varying model sizes. Our experiments compare two LLaVA variants (7B and 13B parameters) across three dataset configurations: standard CLEVR, monocular BiCLEVR, and binocular BiCLEVR. Results reveal a nuanced relationship between model capacity and the ability to leverage stereoscopic information. The larger model demonstrated significant performance improvements with binocular input, while the smaller model showed degraded performance, suggesting insufficient capacity to process the additional visual information effectively. Particularly notable were improvements in numerical comparison and counting tasks for the larger model, indicating that stereoscopic cues enhance object individuation abilities. These findings contribute to our understanding of how vision-language models process spatial information and provide a pathway toward more robust visual reasoning systems capable of understanding 3D relationships in complex environments.Item Embargo Active Removal of Tumbling Orbital Debris Using an Autonomous Chaser Vehicle in the Presence of Perturbations(2025-07-02) Adolph, Mathew; Not Applicable; Master of Applied Science; Department of Mechanical Engineering; Not Applicable; n/a; Not Applicable; Dr. Guy Kember; Dr. Darrel Doman; Dr. Mae SetoTo address and abate the issues related to uncontrolled debris in orbit around Earth, active debris removal (ADR) is imperative. To perform ADR, a chaser satellite is used to rendezvous and capture the debris. Docking with debris is difficult as it is rotating about multiple axes; this is known as tumbling. This thesis details the development of an autonomous flight control strategy that attempts to synchronize and dock with tumbling debris in orbit to facilitate capture. The control strategy employs a model predictive control algorithm to predict the future state of the chaser and debris while simultaneously layering a separate closed-loop attitude controller to orient the chaser towards the debris. The control strategy was shown to successfully dock to debris tumbling at 2.6 deg/s with a 0% failure rate when at an initial separation of less than 25 m from the debris. The chaser was also able to reliably dock in less than 5 minutes to debris tumbling up to 4.5 deg/s when initially positioned 2.45 m from the debris. This research demonstrates that a single control scheme can potentially be used to successfully service a wide variety of candidate debris missions and docking conditions. The control strategy also demonstrates disturbance rejection, including recovery from a simulated micro-asteroid impact. The implemented algorithms were developed to integrate with a planar air-bearing testbed for future validation of the control strategy using hardware.Item Open Access FRONTAL PLANE LANDING MECHANICS AND GLUTEUS MEDIUS MUSCLE ACTIVITY IN INDIVIDUALS RETURNED TO SPORT POST ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION(2025-07-09) Galloway, Ewan; Not Applicable; Master of Science; School of Physiotherapy (Rehabilitation Research); Received; Dr. Christopher MacLean; Not Applicable; Dr. Rebecca Moyer; Dr. Scott Landry; Dr. Derek RutherfordKnee injuries, particularly to the anterior cruciate ligament (ACL), are common and can negatively impact joint health. These injuries often occur during high-impact movements, such as landing from a jump. While jump landings are used in rehabilitation and return-to-sport protocols, current assessments lack sensitivity in identifying individuals at risk. This thesis investigated differences in peak frontal plane projection angle (FPPA) and gluteus medius (GMed) activity during single-leg landings, as well as the relationship between FPPA, GMed activity, and hip abductor strength. Twenty-five individuals post-ACL reconstruction (ACLR) and 25 asymptomatic controls performed single-leg drop landings and maximal voluntary isometric contractions. No significant differences in peak FPPA were found between groups, but the affected limb in the ACLR group showed greater FPPA than the unaffected limb. No group differences were observed in GMed activity. However, lower GMed activity and hip abductor strength were significantly associated with greater FPPA.Item Open Access Enhancing the Monogastric Gut Microbiome Through Innovative Nutritional Strategies(2025-07-05) Lu, Jing; No; Doctor of Philosophy; Department of Animal Sciences and Aquaculture; Received; David Huyben; Yes; Renee Petri; Beth Mason; Vasantha Rupasinghe; Stephanie CollinsThe host and microbiome can be viewed as one integrated system, which highlights the need to optimize nutrition for both the host and its gut microbiome. This thesis explored the use of nutritional strategies as selective forces to support gut microbiome diversity and resilience and ultimately improve host health and adaptability, particularly in those facing loss of host genetic and microbial diversity. Two model species, chickens (Studies 1 and 2) and polar bears (Study 3), were used to investigate gut microbiome modulation from developmental (early life vs. adult stage) to ecological (agriculture vs. conservation) contexts. Study 1 investigated reinforcing deterministic selection during early life to facilitate a lasting gut microbiome modulation through the priority effect in broiler chickens. In ovo delivery of seaweed polyphenols significantly reduced the abundance of a necrotic enteritis-causing genus, Clostridium sensu stricto 1, in the ileum of broiler chickens by day 28 post-hatch, similar to long-term supplementation of in-feed antibiotics. Study 2 examined the role of diet as a strong selection force during the production phase in two commercial strains of laying hens. Dietary inclusion of black soldier fly larvae meal (BSFLM; 0%, 6.5%, and 13%) significantly increased cecal microbial diversity and shifted short-chain fatty acid profiles toward higher acetic acid production. The 13% BSFLM inclusion increased nitrogen and ammonia excretion, which was alleviated by protease supplementation, suggesting that increased microbial diversity may reflect suboptimal protein utilization and proliferation of proteolytic taxa. Study 3 shifted focus to wildlife and compared the fecal microbiome of wild and captive bears to understand the influence of environmental factors. Captive bears had greater fecal microbial diversity, and a distinct community structure compared to wild bears. Individual variation was the main driver of microbial differences among captive bears. Captive bears fed seaweed, a natural dietary item for wild bears, showed minimal change in fecal microbiome. Together, these findings demonstrated the potential of gut microbiome-informed nutritional strategies to promote animal gut microbial resilience across life stages and in both agricultural and conservation settings. Microbial diversity should be interpreted with functionality and interaction with the host to fully understand its implications.Item Open Access Evaluation of Metal Ion-Releasing Glass Particles to Enhance Antibiotic Efficacy Against Cystic Fibrosis Infection(2025-06-30) Wolverton, Maxwell; Not Applicable; Master of Applied Science; School of Biomedical Engineering; Not Applicable; Dr. Mark Filiaggi; Not Applicable; Dr. Daniel Boyd; Dr. Zhenyu Cheng; Dr. Brendan LeungIn cystic fibrosis (CF), thickened airway mucus impairs mucociliary clearance, leading to chronic bacterial infections that cause lung damage and respiratory failure--the leading causes of mortality in CF patients. Although antibiotics are the primary treatment, incomplete bacterial eradication can promote antibiotic resistance. This project investigates whether combining conventional antibiotics with antibacterial metal ions delivered via borate bioactive glass can improve treatment efficacy. An in vitro airway infection model was developed to mimic the CF lung microenvironment using bronchial epithelial cells, a mucus-like hydrogel, and bacteria deposited via an aqueous two-phase system. Bioactive glass formulations demonstrated additive and synergistic antibacterial effects against common CF bacteria when used with antibiotics, without harming epithelial cell viability. These findings suggest that antibiotic-glass combinations may enhance bacterial clearance in CF airway infections and reduce the risk of resistance development, offering a promising therapeutic strategy for CF patients and others vulnerable to persistent lung infections.Item Embargo Data-Driven Design: Leveraging Predictive Modeling for the Development of Soluble and Insoluble Glasses for Medicine(2025-06-25) Kettlewell, Brenna; Not Applicable; Doctor of Philosophy; School of Biomedical Engineering; Not Applicable; Dr. Anthony Wren; Yes; Dr. John Frampton; Dr. Locke Davenport-Huyer; Dr. Mark Glazebrook; Dr. Daniel BoydThe rational design of biomaterials that interact with biological systems to promote healing and regeneration remains a central challenge in medicine. Traditional materials discovery approaches, particularly for bioactive glasses, are limited by trial-and-error methods. This thesis adopts a data-driven approach aligned with the Materials Genome Initiative (MGI) to predict composition-property relationships in both soluble and insoluble glasses for medicine. A systematic investigation of 23 multi-component soluble borate glasses enabled the development of statistical models capable of predicting the individual and interaction effects of glass constituents on structure, dissolution, ion release, and cytocompatibility. In parallel, 16 aluminosilicate glass microsphere formulations were developed for transarterial radioembolization (TARE), optimized for thermal and chemical stability, low cytotoxicity, and compatibility with CT and SPECT imaging. Across both systems, predictive modeling enabled the identification of optimal formulations, demonstrating the power of integrated experimental and computational strategies in advancing bioactive glass design for clinical applications.Item Embargo Groceries Online - Eating, Acquisition, & Technology (GO-EAT)(2025-07-04) Wong, Helen; Not Applicable; Doctor of Philosophy; School of Health Administration; Received; Dr. Sophie Desroches; Yes; Dr. Sara Kirk; Dr. Irena Knezevic; Dr. Leia Minaker; Dr. Catherine MahGrocery shopping is important for healthy eating. Online grocery shopping (OGS) has become popular in Canada, but its impact on diets remains unknown. With a multi-methods approach informed by the Theory of Planned Behaviour, this thesis by manuscript examined how OGS, and digital touchpoint usage (any instances when a consumer interacts directly or indirectly online with a brand, company, or business) in grocery routines, contributed to food-related purchasing decisions and diets. Healthcare professionals who were 18-64 years old and OGS consumers were recruited in Nova Scotia. Interviews were conducted with ten participants and in-depth behavioural questionnaires were administered over a 28-day study period to seven participants. This thesis identified ‘how’ (i.e., behaviours) participants shopped online for groceries and used digital touchpoints, but also the ‘why’ (i.e., beliefs) behind their behaviours. Findings support the importance of considering individuals as free agents and key implications for environmental restructuring in healthy eating behaviours.