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Recent Submissions
OLFACTORY DISCRIMINATION, REVERSAL LEARNING AND OVERTRAINING EFFECTS IN NRXN1+/- AND NRXN1+/+ MICE IN AN OPERANT OLFACTOMETER
(2025-08-30) Ortibus, Wyatt; No; Master of Science; Department of Psychology and Neuroscience; Received; n/a; No; Dr. Simon Gadbois; Dr. Tamara Franklin; Dr. Ian Weaver; Dr. Richard Brown
Autism spectrum disorder (ASD) is characterized by deficits in social communication, social interaction, repetitive behaviours, and poor responses to social cues. ASD is most likely caused by multiple interactions between environmental and genetic factors, including the Neurexin (NRXN) family of membrane protein synaptic organizers. These proteins are implicated in neurodevelopmental disorders, such as ASD and schizophrenia, due to their unique functions at the synapse. Neurexins are encoded by three genes (Nrxn1, Nrxn2, and Nrxn3) and classified into three isoforms (α, β, and γ), all of which are thought to have specific functions at the synapse by binding to postsynaptic neuroligins. These cell adhesion proteins modulate synaptic transmission and downstream gene regulatory networks (e.g., DAT) that control neural function. Nrxn1 gene disruption leads to synaptic destabilization and cognitive impairment, suggesting that Nrxn1 may play an important role in learning and memory. Using an operant olfactometer, we tested cognitive flexibility in wild-type (C57BL/6J) and Nrxn1+/- mice, which were developed as a model for human autism. We used rodent translational studies to examine the cognitive and behavioral consequences of alterations (e.g., knockdowns) in the Nrxn1 genes. Our novel Nrxn1+/- mice have a 140 bp deletion knocking down the α, β, and γ isoforms and have no learning and memory comparisons to wild-type controls. Mice were trained at 2-4 months of age to discriminate an initial odour pair (A vs. B) to a criterion of 85% accuracy, then to a criterion of 85% accuracy on a second odour pair (C vs. D), and then to a criterion of 85% accuracy on reversal learning of the second odour pair, where the rewarded outcomes are switched (S+ becomes S- and vice versa). Secondly, we tested for overtraining effects by overtraining mice on the second odour pair for an extra 180 trials after 85% accuracy criterion before a reversal to study its effects on total errors in reversal. Our results found no significant memory performance differences between Nrxn1+/- and wildtype (C57BL/6J) littermates in the initial odour pair discrimination, second odour pair discrimination or reversal learning discrimination. We also observed no sex differences or interactions on total errors in these discriminations, as well as no effect of overtraining on any of the genotypes compared to mice that were not overtrained. Our investigations into individual learning differences using our models determined common response phases in learning styles during tasks. We used signal detection theory to examine these learning style patterns in the olfactometer based on four possible outcomes: hits, misses, false alarms (FA), and correct rejections (CR). Using these responses, we coded discrimination and reversal learning styles into four different learning phases, which we defined as Perseverance (Misses & FA), Responds None (Misses & CR), Responds All (FA & Hits), and Respond S+ (Hits & CR). These phases of reversal learning allow us to analyze individual differences and explain how mice perform operant reversal tasks within an olfactometer. Our reversal learning theory also showed that “Learning to Learn” performance increases in reversal learning tasks is the reduction of Perseveration and Responds None responses. Future studies should consider the effects of age on reversal learning to determine whether age affects cognitive flexibility in the Nrxn1+/− mouse model.
Adapting Health Economic Evaluation Metrics to Incorporate Estimates of Environmental Impact: An Examination of Spinal Laminectomy and Fusion Procedures in Canada
(2025-08-29) Nsitem, Kelachi; No; Master of Science; Department of Community Health & Epidemiology; Not Applicable; na; Yes; Sean Christie; Mohammad Hajizadeh; Daniel Rainham; George Kephart
Climate change is an urgent threat to public health, yet healthcare contributes substantially to environmental damage. This thesis explores how environmental impacts can be incorporated into health economic evaluations to support sustainable healthcare decision-making. A narrative review synthesized literature on ecological economics, planetary health, and sustainable healthcare to identify key themes relevant to health technology assessment. An empirical analysis examined the environmental footprint of a common surgical procedure, using real-world data to estimate emissions and explore opportunities for reduction. While environmental costs were small relative to total healthcare costs, they revealed where emissions are concentrated, and which aspects of care may be more easily changed. Patient travel emerged as a key contributor and a target for low-disruption reductions. By combining conceptual insights with practical analysis, this work demonstrates how environmental costs can be integrated into healthcare evaluation frameworks, helping healthcare systems align service delivery with broader climate and sustainability goals.
Digital Scribing: Applications of Accessible Hyper-Imaging in Architectural Design
(2025-08-26) Samuel, Beckley; Not Applicable; Master of Architecture; School of Architecture; Not Applicable; Joyce Hwang; Not Applicable; Huschang Pourian; Roger Mullin
This thesis explores the application of scanning technology to architectural scribing techniques using digital, analogue and hybrid workflows. The project investigates ishibadate a traditional Japanese footing technique as a case study for precise scribing of manufactured material to a natural surface. The thesis then looks for avenues where digital workflows could be useful in the manufacture of precisely scribed material in an architectural context.
INVESTIGATING THE EFFECT OF CEMENT STABILIZATION ON A SLATE WASTE ROCK
(2025-08-30) Walker, Matthew; Not Applicable; Master of Applied Science; Department of Civil and Resource Engineering; Not Applicable; n/a; Not Applicable; Gordon Fenton; Rob Jamieson; Craig Lake
Acid-producing waste rock is a by-product of urban construction, and its environmental impact necessitates proper disposal. Cement solidification and stabilization is a technique to limit the effect of acid drainage leaching from waste rock material and consists of mixing the waste rock with a cementitious binder, followed by placement in a containment cell. This technique aims to reduce water flow through the material and to increase the pH/decrease effluent contaminant concentrations. Many test methods are available to assess the performance of the stabilized material. Humidity cell testing weathers the treated material over time by repeatedly exposing the stabilized mixture to cycles of air and water. Based on humidity cell testing performed, the cement stabilization was effective in neutralizing the pH of the effluent leachate and slowing the release of most contaminants. Notable exceptions were sulfur and sulfate, which were detected in higher concentrations in the binder treated samples.
Numerical Simulations of a Simplified Aeroengine Bearing Chamber
(2025-08-30) Boudreau, Eric; Yes; Master of Applied Science; Department of Mechanical Engineering; Not Applicable; Dr. Sophia He; Not Applicable; Dr. Mohammad Saeedi; Dr. Dominic Groulx; Dr. Baafour Nyantekyi-Kwakye
This research presents a comparison of several numerical multiphase approaches used to study a simple bearing chamber. Oil film thickness and scavenge efficiency are the main indicators used to quantify performance, and the models are validated against published experimental data. The test case conditions are meant to represent the transitional flow regime, which is the point at which viscous forces overcome the gravitational forces in the film. This case is particularly challenging to resolve due to high rotational speeds and large gradients in the film thickness.
A novel approach was developed which couples Discrete Phase Modelling (DPM) for oil droplets, Lagrangian Wall Film (LWF) for thin-films, and Volume of Fluid (VOF) for thick-films. The technique was then used to validate two additional bearing chamber configurations: a protruded vent and a covered ramp leading to the scavenge pipe
Urban-Rural Divide: Investigation of Travel Patterns, Work Arrangement Choices, and Electric Vehicle Preferences in Nova Scotia
(2025-08-28) Ghani, Maisha; Not Applicable; Master of Applied Science; Department of Civil and Resource Engineering; Not Applicable; NA; Not Applicable; Dr. Lei Liu; Dr. Uday Vnekatadri; Dr. Ahsan Habib
This thesis addresses the long-standing urban-centric bias in transportation research by foregrounding the urban–rural divide as a critical dimension for sustainable and inclusive mobility planning in the post-pandemic era. Using data from the 2022–23 Nova Scotia Travel Activity (NovaTRAC) survey, conducted across diverse communities, it evaluates multiple sampling methods, civic address, landline, cellphone, and social media, to improve representation, especially among hard-to-reach rural households. The mixed-mode approach captures socio-demographic, behavioral, and attitudinal differences across regions, offering a comprehensive portrait of how Nova Scotians live, move, and work. A Hybrid Choice (HCM) framework integrates observed and latent factors to explain both choices and motivations. The analysis focuses on two domains: public electric vehicle charging location preferences, highlighting region-specific infrastructure needs, and post-pandemic work arrangements, showing how contextual and attitudinal factors influence decisions. Findings clarify spatial inequities and inform inclusive EV infrastructure planning, flexible work policies, and sustainable mobility strategies.