title: Microbial Modulation of Vagal Afferent Neurons in Inflammatory Bowel Disease and Obesity

contributor:
Lomax, Alan
Neuroscience Studies

subject:
Nodose ganglia
Inflammatory bowel disease
Obesity

abstract: Background: The gut-microbiota-brain axis has received increasing attention recently due to evidence that colonic microbes can affect brain function and behavior. Vagal afferent neurons are an important conduit between the gut microbiota and the brain, as they can detect mediators released from the gut microbiota. However, much remains unknown regarding the innervation of the colon by vagal afferent neurons and how gut microbiota dysbiosis during inflammatory bowel disease (IBD) and obesity impacts the function of these neurons. Aims: i) Assess the extent of vagal afferent colonic innervation using the retrograde labeling technique. ii) Examine the excitability of nodose ganglion (NG) neurons exposed to fecal supernatants (FS) from 5 Crohn’s disease and 7 ulcerative colitis patients, and 5 healthy volunteers (HV) and the mechanism underlying that. iii) Study the effect of FS from obese and control mice, 12 obese patients (7 females/ 5 males), and 7 HV on NG neuronal excitability and the mechanism underlying that. iv) Examine whether depletion of microbiota by antibiotics alone or followed by fecal microbiota transplantation (FMT) could alter eating behavior and NG neuronal excitability in mice. Methods: Current and voltage-clamp recordings were used to assess changes in neuronal excitability and ion channel function. Results: i) 25 % of NG neurons innervate the colon, and 8 % innervate the distal colon. Single NG neurons innervate both the proximal and distal colon. ii) FS from active CD and UC patients, but not HV increased NG neuronal excitability and significantly reduced voltage-gated K+ current density. Cysteine proteases mediate the effect of FS from IBD patients on NG neurons by activating the protease-activated receptor 2. iii) FS from obese mice and patients decreased NG neuronal excitability and significantly increased voltage-gated K+ current density. This inhibitory effect was blocked by orexin-receptor antagonists. iv) Bacterial depletion decreased food intake by one-third in obese mice but increased it by twofold in control mice, suggesting that the microbiota of obese mice contributes to excessive caloric intake during obesity. v) FMT from obese or control mice into antibiotic-depleted mice was sufficient to induce eating behavior alterations similar to the donors. Collectively, these findings suggest that remodeling of gut microbiota during IBD and obesity increases the secretion of microbial mediators that change the excitability of NG neurons.

abstract: PhD


title: In situ and operando Monitoring of Laser Additive Manufacturing

contributor: Physics, Engineering Physics and Astronomy

rights: Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada

rights: ProQuest PhD and Master's Theses International Dissemination Agreement

rights: Intellectual Property Guidelines at Queen's University

rights: This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.

rights: Attribution-NonCommercial-ShareAlike 3.0 United States

subject:
Inline coherent imaging
Additive manufacturing
Laser material processing
Optical coherence tomography
Synchrotron X-ray imaging

abstract:
Metal laser additive manufacturing (LAM) is increasingly being used for manufacture of high-value, safety critical components. However, it still suffers from a lack of in situ quality assurance and control. In this thesis, an interferometric monitoring technique called inline coherent imaging (ICI) is applied to LAM for high-speed (200 kHz) in situ morphology measurements and defect detection.

The Fraser group powder bed fusion (PBF) machine was used to demonstrate manual layer-wise control of a 3D build of 316L stainless steel with a seeded unsupported region. Surface roughness was corrected by ablating raised areas and infilling depressed areas of each layer based on post-processing ICI measurements (54% decrease in max. S_a). ICI was then combined with high-speed synchrotron X-ray imaging for correlative monitoring of LAM. ICI was integrated into a directed energy deposition (DED) machine with a novel off-axis imaging beam delivery and micro-electromechanical systems (MEMS) scanner for alignment and positioning. ICI was used to monitor DED track morphology during thin-wall builds of nickel super-alloy CM247LC, an alloy used for turbine components susceptible to cracking under LAM conditions. ICI provided immediate diagnostics on the DED process, including material deposition rate, track width, and surface roughness and waviness. Humping (large surface waviness) in thin-walls reduces geometric accuracy and leads to increased residual stress in valleys, which can induce cracking. ICI was used to in situ detect humping and crack openings, simultaneous with X-ray observation of sub-surface crack growth at the Diamond Light Source (DLS). ICI was then integrated into the PBF test rig at the Advanced Photon Source (APS) for simultaneous ICI and X-ray imaging of PBF. Simultaneous radiography was used to validate ICI depth measurements from the keyhole during laser welding and PBF of aluminum alloy 6061. Even in a turbulent pore-generation mode, ICI depth measurements from the keyhole corresponded closely with the keyhole depth extracted from radiography (>80% within ±15 µm). A ray tracing simulation confirmed that outliers in ICI data are often the result of multiple reflections within the keyhole (57%). ICI depth signatures for bubble and pore formation were also identified, capturing keyhole pinching, “pull-up,” and spiking phenomena.

abstract: PhD


title: Development of Amphiphilic Biohybrid Hydrogels for Cell Delivery to the Nucleus Pulposus

contributor:
Amsden, Brian
Chemical Engineering

subject: Biomaterials Hydrogel

abstract:
Restoration of the nucleus pulposus (NP) by cell therapy has emerged as a promising treatment for intervertebral disc degeneration. Hydrogel scaffolds have been used as vehicles to deliver cells to the NP, but their efficacy has been limited by brittleness, degradation, and swelling. This thesis focused on the development of amphiphilic, biohybrid hydrogels with controlled swelling for cell delivery.
The polymerization mechanisms for an amphiphilic poly(trimethylene carbonate) bearing methoxyethoxy side groups was investigated to allow for the synthesis of a well-defined backbone for the hydrogel. Monomer purity and catalyst selection were important factors in achieving a heterobifunctional architecture and predictable molecular weight as they could reduce the degree of autoinitiation during polymerization. These findings allowed for the synthesis of poly(trimethylene carbonate) bearing methoxyethoxy side chains with terminal methacrylate and vinyl sulfone groups. This heterobifunctional polymer could then be incorporated into a triblock copolymer with the pattern ABA, where A is the heterobifunctional polymer and B is a MMP cleavable peptide.
The triblock copolymer was crosslinked using ammonium persulfate and sodium bisulfite to initiate radical crosslinking. The thermal initiation system was minimally cytotoxic with cell viability above 75 % and did not cause side reactions with the peptide sequence. The resulting hydrogels were macroporous due to a thermoresponsive phase separation and were able to support NP cell proliferation and the deposition of collagen type II.
The triblock structure limited molecular weight control, as the copolymer depended on the molecular weight achieved in the preliminary ring-opening polymerization. To allow for more flexibility in a similarly modular system, a suite of multiblock copolymers with the pattern (AB)x, where is A is a synthetic polymer and B is the peptide, were synthesized. A base catalyzed thio-acrylate reaction was used to achieve chain extension of pre-synthesized A and B blocks. Using poly(trimethylene carbonate) and poly( -caprolactone) as model synthetic blocks, it was demonstrated that the extent of the chain extension depended on the size of the blocks but not on their composition. Preliminary assessment demonstrated the hydrophobic residues in the peptide created physical crosslinks leading to hydrogel formation.

abstract: PhD


title: Quantitative Characterization of Heat Transport in Fractured Rock

contributor:
Kueper, Bernard
Novakowski, Kent
Civil Engineering

subject:
Fractured rock
Heat transport
Numerical modeling
Analytical solution

abstract: The quantitative characterization of heat transport in fractured rock is a crucial yet challenging task due to the complexity of the heat exchange between the fluid and solid phases and the specific applications of interest. The aim of this study was to identify the key variables controlling the complex thermohydrological processes and to estimate the temperature variances fully accounting for the properties of heat source, groundwater influx, and rock matrix. The study involved sensitivity analyses using a proposed implementation scheme based on Latin-hypercube-one-at-a-time (LH-OAT) method using numerical simulation. The numerical model was developed with a domain of 100 × 50 × 25 m including a top fractured rock layer (15 m), a bedrock layer beneath (10 m), and a heating area. Further heat dissipation study was conducted using a detailed hydrogeological data set from a well-characterized field site. In addition, a 2-D semi-analytical solution was derived to estimate the fracture or rock matrix temperatures. The sensitivity analyses using the modified LH-OAT method successfully ranked the variables based on their significance on matrix temperature variances: heat source > groundwater influx > rock matrix. The heat source scaling was demonstrated to have a decisive impact on temperature variance in the input variability space, yet it appears to have strong correlations with other factors. A correlation between the heat dissipation effect in the heating zone and the transmissivity of fractured rock was also identified based on the case study by numerical modeling. A mathematical relationship between groundwater influx, heat source, and temperature variance was described using the derived semianalytical solution that fully coupled the advective and conductive heat transport in the fracture fluid and heat conduction in the rock matrix. The generality of the solution greatly facilitates the definitions of the heat source dimensions and the energy delivery strength. The transient temperature analyses highlight the significance of a heat source in the rock matrix and imply that the spatial temperature variation is strongly associated with heat delivery strength. The early time temperature variances can be attributed to the heat source configuration and the later time temperature is mainly controlled by the amount of delivered energy.

abstract: PhD


title: Deep Model-Based Reinforcement Learning for Sample Efficient Predictive Control

contributor:
Givigi, Sidney
Computing

subject:
Reinforcement Learning
Control
Robotics

abstract:
Deep reinforcement learning algorithms provide a framework for learning high performance solutions to complex problems without explicit knowledge of the systems with which the algorithms are interacting. These algorithms are of particular interest for the fields of control and robotics, which traditionally rely on exact knowledge of the system dynamics and of the desired solutions. However, most state-of-the-art deep reinforcement learning algorithms require a large amount of interaction with a system before learning an effective solution, and have problems with learning solutions when we express the effectiveness of a given solution using only sparse signals given upon failure or success in solving a problem. These problems limit the applicability of deep reinforcement learning methods to real-world systems, where data is difficult to collect and problems are naturally expressed in the form of binary successes or failures. Additionally, deep reinforcement learning algorithms are difficult to analyse due to the difficult to interpret nature of artificial neural networks.

In this work, we propose and evaluate a deep model-based reinforcement learning algorithm for control which is able to learn effective solutions in far fewer interactions with the environment when compared to model-free state-of-the-art algorithms, both with sparse and dense rewards. The first proposed algorithm learns a policy competitive with that of model-free algorithms with about 47% as many episodes on a dense reward inverted pendulum on a cart task, and learns a policy which matches the maximal performance of the best performing model-free algorithm in less than 6% of the number of episodes on a sparse reward reach-avoid game. We verify the functioning of the algorithm on a real-robot experiment with no fine-tuning. We propose two variants of the algorithm that use quadratic neural networks to extract analysable predictive controllers, improving the interpretability of the method and allowing us to use nonlinear optimization methods to select actions. The version of the algorithm that uses dense neural networks as an intermediate during training reduces the number of episodes needed to learn a solution to the inverted pendulum on a cart to 8.1% of the first algorithm, or 3.8% of the model-free algorithms. We also provide analysis of a known phenomenon referred to as policy oscillation that affects approximate dynamic programming algorithms, as well as one of the proposed methods.

abstract: M.Sc.


title: Numerical Simulation of Dam Breach with XBeach

contributor:
Take, W. Andy
Mulligan, Ryan P.
Civil Engineering

subject:
sediment transport
erosion
XBeach
overtopping
tailings dam
overtopping
dam breach

abstract: A dam breach is defined as the uncontrolled release of material retained in the impoundment. The resulting flow of water, or mine waste can be catastrophic to the environment, local infrastructure, and human life. Engineered dams and sand dunes are studied by different academic communities. This thesis recognizes that breaching in coastal environments is an analogous problem to overtopping engineered dam failures and proposes that similar tools can be used in both scenarios. The goal of this project is to determine if the XBeach model, traditionally used by the coastal engineering community, is a reliable tool in simulating overtopping dam breach failure by validating breach simulation outcomes against the physical laboratory conditions of Walsh (2019). The first objective of this study was to explore the model parameters necessary for overtopping failure simulation. Results indicate that breach is most accurately simulated when the Soulsby – van Rijn sediment transport formulation is selected and the avalanching module of the model is turned on. Using these conditions, the model could accurately simulate the upstream erosional control and define the outflow hydrograph for four upstream slope angles ranging from 10.0o to 30.0o. After validation, five simulations of dams with beach intersection heights ranging from 0.50 cm to 0.90 cm were conducted to determine whether XBeach can capture the outflow hydrograph and quantify the volume of eroded material with the presence of a tailings-style beach. Through the quantitative comparison of physical and numerical model outcomes, it was concluded that XBeach can reproduce the bulk characteristics of a tailings style dam breach failure. Considering the peak outflow value of the breach hydrograph, XBeach results saw most cases within 25% of the physical laboratory observations. Focusing on a cross-sectional centreline of the physical and numerical studies, it was found that both models produce a similar magnitude of eroded material with the percent difference of eroded material being less than 10% in all test configurations.  Overall, this investigation supports a growing case for the use of XBeach in field-scale numerical simulation and to extend the capabilities of the model.

abstract: M.A.Sc.


title: The Structure-Function Relationship and Applications of Noble Metal Nanomaterials

contributor:
Stamplecoskie, Kevin
Chemistry

rights: Attribution-NonCommercial-NoDerivs 3.0 United States

subject:
Nanomaterials
Chemistry
Materials Science

abstract: Noble metal nanoparticles have been studied for decades and used as the basis for countless materials. From catalysis to chemical sensing, important applications rely on the continued development and understanding of these unique and powerful materials. Nanomaterials owe their utility and precise function to their size, shape and support, or in other words, their structure. In order to continue to push nanomaterials forward and realize new and improved applications, we must develop materials that can address issues of surface stability without sacrificing the important electronic and optical properties of nanoparticles. Improving our understanding of the interplay between structure and function will help these already widely used materials achieve their true utility. To accomplish these goals, this thesis was directed towards the structure tailored application of nanoparticles with the following major contributions: In this thesis, (1) A stabilization method of colloidal silver nanoparticles on an aluminum oxide scaffolding is investigated and reported. (2) A photochemical shape control method is applied to both solid phase and colloidally stabilized silver systems, offering stable particles with tailored optical properties. (3) Colloids of metal oxide stabilized silver and gold nanoparticles are showcased as redox catalysts for the template reduction reaction of 4-nitrophenol, offering insights into the importance of surface site availability. (4) Silver nanoparticle thin films are showcased as reliable and stable chemical sensors for surface enhanced Raman spectroscopy. The parameters of particle loading, and shape are optimized, and films are used to sense the pesticide thiram at trace concentrations. (5) A cellulose-gold nanoparticle hybrid material is synthesized and showcased as a hydrovoltaic device. In each of the applications investigated, specific tailoring of the surface chemistry and properties of the metal nanoparticles has been controlled as the key parameter for optimizing the materials for that application. Chapters 2-5 are presented in concise, manuscript form and much of the relevant information pertaining to these works are referenced in the respective appendices.

abstract: PhD


title: Pore Pressure Dissipation and Reconsolidation Observed in Large Scale Experiments of Liquefied Debris Flows

contributor:
Take, Andy
Civil Engineering

subject:
Landslide
Pore pressure
Debris flow
Liquefaction
Consolidation

abstract: Debris flows can have devastating consequences due to their high speeds, far distal reach, and sudden occurrence. The high mobility of debris flows is often attributed to liquefaction, which can reduce basal friction to near zero and cause fluid-like properties. Consolidation of liquefied materials occurs when the generated excess pore pressures dissipate, and grain contacts and effective stress are regained. The evolution of excess pore pressures and their persistence following deposition must be considered in numerical solutions to predict mobility and understand the risk of remobilization. The objectives of this research were twofold i) to develop a cost-effective and field-applicable test method for calculating the consolidation parameters of liquefied granular materials and ii) to investigate the evolution of pore pressures in debris flows and its effect on mobility. This thesis presents a novel test method to calculate a spatially and temporally variable coefficient of consolidation, the relationship between one-dimensional stiffness and effective stress at low effective stresses, and estimate surface settlement, using two analytical and one numerical model. Estimates of the coefficient of consolidation were similar across the three models and model estimates of settlement matched experimental results well. We also present results from twelve large-scale flume tests carried out at source volumes of 0.2, 0.4, 0.6, and 0.8 m3 of a well-graded granular material with a consistent water content. Excess pore pressures were observed throughout travel and dissipated following flow arrest. Estimates of the coefficient of consolidation matched well with results from the small-scale field test. Pore pressures were found to affect debris flow mobility, as mobility increased with source volume, which was not seen in previous dry tests, and increased spreading compared to previous tests where excess pore pressures did not develop. We anticipate the novel field-deployable test provides an accessible and valuable tool for investigating field events of debris flows, tailings dams and seismic areas, and the debris flow test series is an experimental dataset that can be used in calibration of both theoretical and numerical models of pore pressure evolution and mobility predictions.

abstract: M.A.Sc.


title: Optimizing Real-Time ECG Data Transmission in Constrained Environments

contributor:
Hassanein, Hossam
Elgazzar, Khalid
Computing

subject:
ECG real-time transmission
Lossless compression
ECG in constrained environments
Power consumption optimization
Adaptive ECG leads selection

abstract:
ECG monitoring systems have a significant role in detecting cardiovascular diseases and reducing the rate of sudden cardiac deaths through early warnings for heart attacks. One of the critical factors in supporting real-time ECG tracking is to guarantee monitoring system availability. This thesis focuses on battery life extension for a 12 Lead ECG patch utilizing compression and classification approaches.

In the compression approach, the ECG patch operational hours are extended by reducing the data size of captured ECG signals to minimize the Bluetooth Low Energy communication airtime and the overall transmission power. Huffman, delta, and base-delta lossless compression techniques are implemented on a Texas Instruments CC2650 Micro-controller Unit using different sampling rates, normal, and abnormal cardiac conditions. The algorithms are evaluated in terms of compression ratio, execution time, and power consumption of the ECG patch.

The computer-aided interpretation of ECG signals has become a pivotal tool for physicians in the clinical assessment of cardiovascular diseases during the last decade. Therefore, computerized diagnosis systems depend heavily on machine learning and deep learning models to guarantee high classification accuracy. With the classification approach, we target effective power consumption by controlling the ECG patch mode of operation to reduce the need for a full-fidelity ECG signal. We use a binary classifier to inform the decision to switch between different operational strategies. In addition, we provide a new approach to support energy-efficient ECG monitoring in real-time through the adaptive selection of ECG leads after applying multi-class classification to the raw ECG signals. We deploy CNN model scenarios on MIT-BIH and CODE-test datasets and adjust the number of ECG streamed channels to 1,4, and 8, based on the detected cardiac abnormalities, such as arrhythmias and heart blocks.

Our findings show that the base-delta encoding technique outperforms other compression techniques and achieves 70\% data compression on normal ECG data, and up to 50\% on abnormal ECG data with 24 ms. The adaptive selection of ECG channels with CNN models on 1 and 12 leads achieves 77.7\% power saving in the normal cardiac condition and up to 55.5\%
for the heart blocks, sinus bradycardia, and sinus tachycardia.

abstract: M.Sc.


title: Multitiered Worker-Oriented Resource Allocation at the Extreme Edge

contributor:
Hassanein, Hossam
Computing

subject:
Edge Computing
Extreme Edge
Extreme Edge Devices (EEDs)
Fair Resource Allocation
Optimization

abstract: Democratizing Edge Computing (EC) by leveraging the prolific yet underutilized computational resources of IoT devices, also referred to as Extreme Edge Devices (EEDs), has gained significant momentum lately. In such edge computing paradigms, fair resource allocation is a major concern. However, fairness is typically considered from the requester’s perspective, whereas fairness for workers is mostly overlooked. In this thesis, we propose the Multitiered Worker-oriented Resource Allocation (MWORA) framework. MWORA aims to minimize the drop rate and task response delay while enabling fair resource allocation that maintains a specific satisfactory profit for workers. Such a satisfactory profit is maintained to prevent workers from leaving the system and ensure their recurrent subscription to the service provider. MWORA also accounts for the fact that EEDs are user-owned devices and are thus subject to a dynamic user access behavior, which can affect the level of computational resources endowed by workers. MWORA considers this by enabling multitiered computational resources to be granted by each worker depending on the price of the allocated task. MWORA formulates the resource allocation problem as an Integer Linear Program (ILP). We also propose the MWORA-Weighted Sum (MWORA-WS) scheme to derive an analytical solution using the Karush–Kuhn–Tucker (KKT) conditions and Lagrangian analysis. Extensive simulations show that MWORA outperforms prominent resource allocation schemes in terms of the average response delay, service capacity, worker satisfaction ratio, and fairness. In addition, it is shown that MWORA-WS closely approaches the optimal solution rendered by MWORA.

abstract: M.Sc.


title: Improving the Efficiency of the Albion Leach Process: Elemental Sulfur Removal from the Residue Using Lanxess Lewatit® AF 5

contributor:
Ghahreman, Ahmad
Pickles, Christopher
Mining Engineering

subject:
Albion Leaching
Chalcopyrite
Lanxess Lewatit® AF 5
Regeneration
Mechanism

abstract:
Elemental sulfur is a key component in the acidic Albion chalcopyrite atmospheric leaching process and is a challenging issue in the residue. The removal of this elemental sulfur from the final leach residue produced during the atmospheric oxidative leaching of chalcopyrite concentrates is both a technical and an economic challenge. Lanxess Lewatit® AF 5 is a microporous carbon-based catalyst and is a promising candidate material that can collect elemental sulfur during the leaching process. This study focuses on removing the elemental sulfur during the acidic Albion leaching process using this new catalyst and regenerating the catalyst via different methods.
Toluene and tetrachloroethylene were studied as potential organic solvents for the removal of the sulfur from the sulfur loaded AF 5. The effects of temperature, time and AF 5 to solvent ratio on sulfur removal from the sulfur loaded AF 5 were examined. The optimum desulfurization conditions were 100 °C for toluene and 110 °C for tetrachloroethylene for an AF 5 to solvent ratio of 1:50 and a processing time of 120 min. Furthermore, the optimum conditions for the removal of sulfur from the catalyst using a high temperature process in a tube furnace were investigated. The results indicated that the maximum desulfurization of 90.1% was achieved at 550 °C after 10 min.
The mechanisms of elemental sulfur adsorption on AF 5 were examined in the leaching test. A series of leaching experiments were performed as a function of temperature, agitation speed and concentrate to AF 5 ratio. Using these results, the adsorption isotherms, the kinetics and the thermodynamics of sulfur removal were studied. Adsorption isotherms at various temperatures were determined using the Langmuir and Freundlich models. The maximum sorption capacity of AF 5 at 95 °C was 488 mg/g. The kinetic data were fitted to pseudo-first order (PFO) and pseudo-second order (PSO) models and it was shown that the PFO model gave the best fit to the results. The rapid kinetics of sulfur adsorption were attributed to the open pore structure of the AF 5. The Gibbs free energy, enthalpy and entropy of sulfur adsorption by AF 5 were determined.

abstract: PhD


title: Advocating for Toronto's Commercial Cleaning Industry Workers: Union and Broad-Based Campaigns, 2000-2018

contributor:
Holmes, John
Kobayashi, Audrey
Geography and Planning

subject: competitive dynamics and structure of commercial cleaning

subject: labour geography

subject: lobbying

subject: city-wide collective bargaining

subject: legislative change

subject: Toronto

subject: Justice and Dignity for Cleaners (JD4C)

subject: Justice for Janitors (J4J)

subject: Fight for $15 and Fairness (FFF)

subject: Fight for $15 (FF15)

subject: privatization

subject: outsourcing

subject: subcontracting

subject: independent contracting

subject: contract flipping

subject: precarious work

subject: industrial relations

subject: competitive bidding

subject: price competition

abstract:
This study examines union and non-union advocacy efforts to improve wages, working conditions, and employment security for workers in Toronto’s downtown commercial cleaning industry in the period 2000-2018. It analyzes the structure and competitive dynamics of the commercial cleaning industry, emphasizing how the competitive bidding structure, price competition, contract flipping, and other company strategies lead to the precarious nature of cleaning work by driving down standards and working conditions. Outsourcing and subcontracting of cleaning services and the prevalence of independent contractors, who lack the protection of a standard employment relationship, create significant challenges for unions seeking to organize a largely racialized and gendered cleaning workforce largely drawn from immigrant communities, many of whom are employed part-time and hold multiple jobs.  The analysis draws on primary research data collected through semi-structured interviews with union organizers, non-union organization activists, and cleaning company owners. Secondary information was obtained through a comprehensive review of legislative and policy documents and media analysis.
 	The study employs three case studies to investigate the efficacy of union and non-union campaigns and strategies to improve wages, working conditions, and employment security for cleaners. The first analyzes a union-led campaign to save the jobs of Toronto’s municipal cleaners threatened by privatization. The second case examines how a union innovative strategy to develop city-wide collective bargaining agreements helped stabilize cleaners’ wages and benefits, improved employment security, and increased unionization within Toronto’s commercial cleaning industry. The final case study focuses on a province-wide social movement to bring about legislative change to improve employment standards and worker protection for Ontario’s low-wage service sector workers, including cleaners.
This research found that both union-led lobbying and collective bargaining strategies and more broadly-based social movements to pressure for legislative change were needed to improve wages, working conditions, and employment security for Toronto commercial cleaning workers during this period.

abstract: PhD


title: Neuro-Symbolic Methods for Natural Language Inference and Question Answering

contributor:
Zhu, Xiaodan
Greenspan, Michael
Electrical and Computer Engineering

subject:
Deep Learning
Neuro-Symbolic Method
Natural Language Processing
Machine Learning
Natural Language Inference
Question Answering
Explainable AI

abstract:
One of the fundamental problems in deep learning research is how to design neural network models to incorporate logic and symbolic operations. Although deep neural network models have achieved state-of-the-art performance on multiple natural language processing benchmarks, those black-box models can hardly provide explanations for their inner mechanisms. They still lack the ability to perform systematic reasoning like human beings and generalize poorly to out-of-distribution samples.

In this thesis, we attempt to overcome these limitations by designing neuro-symbolic models that combine neural network models with natural logic theory. At the lower level, we use neural networks to model the text representation and produce intermediate predictions, while at the higher level, we leverage symbolic operations to perform reasoning, which leads to the final prediction. We apply our neuro-symbolic models to solve the natural language inference (NLI) task, and we also explore ways to extend our method to question answering (QA).

This thesis offers a set of contributions that address the problem of effectively combining deep neural networks with symbolic methods. The first contribution is a novel end-to-end differentiable natural logic model for NLI. Our proposed model achieves empirically competitive results on the Stanford NLI benchmark and multiple stress-test datasets. Our model also provides faithful explanations for its decisions based on natural logic.

The second contribution is a novel neuro-symbolic NLI model, which overcomes the limitations of its predecessor by leveraging a well-designed natural logic program and reinforcement learning. We also propose an introspective revision algorithm that incorporates commonsense knowledge bases to alleviate the spurious reasoning problem and improve training efficiency.

The third contribution is an extension of the neuro-symbolic method to multi-hop QA applications. We propose a model that accurately locates chains of useful evidence, which can be trained without direct supervision, and a neuro-symbolic QA model that performs natural-logic style reasoning on the chains of evidence.

abstract: PhD


title: Lived Experiences of Discomfort in Women with Crohn's Disease

contributor:
Wilson, Rosemary
Camargo - Plazas, Pilar
Nursing

subject:
Lived experiences
Discomfort
Women
Crohn’s Disease
Max van Manen
Hermeneutic phenomenology

abstract:
Crohn’s disease is a subtype of inflammatory bowel disease with a significant disease burden and decreased health-related quality of life. While disease activity plays a vital role in the discomfort experienced by people with inflammatory bowel disease, discomfort is reported even during remission, impacting the patients’ satisfaction with their care. However, although commonly reported in clinical settings and research studies, discomfort lacks conceptual clarity and is often used interchangeably with pain.
Prior research has been directed toward therapeutic management of Crohn’s disease and finding a cure, lacking patients’ perspectives on their lived experiences. In addition, although gender inequalities shape the care received by women with Crohn’s disease, gender-specific studies are lacking in this patient population. Therefore, examining the discomfort lived by women with Crohn’s disease is critical to ensure its proper use in clinical practice and outcome measures. In this thesis, I focused on gaining an in-depth understanding of the meaning of discomfort in women living with Crohn’s disease.
Using a qualitative, hermeneutic phenomenological study, I sought to capture the meaning of discomfort experienced by six Ontarian women living with Crohn’s disease. This interpretive inquiry supported the inclusion of philosophical, philological and human science perspectives. The evocative anecdotes from interviews and the richness of the phenomenological text led to the emergence of four interpretive themes: discomfort as an embodied experience, discomfort as a conscious experience, discomfort and social life and discomfort as a way forward. The findings of this study highlight the complexities of the lived experiences of discomfort, as described by the study participants and their profound ramifications on their physical, psychological, social and emotional wellbeing. Consequently, the results contribute to a strengthened understanding of discomfort as lived by women with Crohn’s disease while emphasizing the need for further exploration and interventions within the clinical, research, policy, and scholarly realms.

abstract: PhD


title: FODMAP availability modulates the influence of the microbiota on visceral afferent neuron activation

contributor:
Lomax, Alan
Reed, David
Biomedical and Molecular Sciences

subject: Microbiota Pain IBS FODMAP Protease

abstract: Abdominal pain is commonly observed in gastrointestinal diseases such as irritable bowel syndrome (IBS). However, it is unclear what role the microbiota plays in the development of abdominal pain. It has been shown that fecal samples from IBS patients excites afferent nerves, but when the same patients are placed on a low fermentable oligosaccharides disaccharides monosaccharides and polyols (FODMAP) diet the fecal samples cause inhibition. It is not clear whether these effects were driven by host derived or bacterial mediators. It was hypothesized that culturing stool microbial communities from IBS patients in vitro will help discriminate between microbial and host contributions to the development of visceral pain by removing host contributions entirely. The fecal cultures were exposed to low concentrations of FODMAPs to simulate a low FODMAP diet, a common treatment for IBS symptoms, to determine whether a reduction of FODMAPs alters production of bacterial neuroactive mediators in vitro. The culture supernatant was collected and perfused through murine colonic preparations while the activation of spinal afferent axons within the mesentery was recorded using extracellular electrodes. Afferent nerve recordings showed no difference between the effects of the original patient stool supernatant and the supernatant obtained after 15 days in culture (N=3 IBS patients). This suggests the cultured stool bacteria produce similar mediators to those contained in the original IBS patient stool samples. When the FODMAP content of the media was reduced, the culture supernatant reduced action potential discharge by 40% (p=0.0008) compared to discharge during a control distention.  This inhibitory effect was blocked by intraluminal perfusion of the protease activated receptor 4 antagonist ML354 (10µM). This work suggests that a popular dietary therapy for IBS may act by altering gut microbiota metabolite secretion.

abstract: M.Sc.


title: Barriers Impeding the Deployment and Uptake of Solar-powered Cold Storage Technologies for  Postharvest Loss Reduction in Tomato Value Chain in Africa: Empirical Evidence from  Tanzania.

contributor:
Goebel, Allison
Environmental Studies

subject:
Post-Harvest
Food Loss
Small-scale Farmers
Tomato
Tanzania
Cold Storage

abstract: In Tanzania, the production of tomatoes is one of the most important economic activities accounting for more than half of the total exports of vegetables. Despite the sector’s economic significance, post-harvest tomato losses remain very high, with almost 50 percent of fresh tomatoes produced by small-scale farmers spoil before reaching destination markets and consumers due to poor post-harvest management. Lack of cold storage facilities is one of the leading causes of massive post-harvest tomato losses, negatively affecting farmers’ incomes and the sector’s economic contribution. In recent years, the adoption of solar-powered cold storage technologies has proved to hold great potential for preventing losses of tomatoes after harvest, especially for small-scale farmers in off-grid locations. However, in several parts of Sub-Saharan Africa, including Tanzania, the deployment of solar-powered cold storage technologies is limited, leaving the vast majority of rural small-scale farmers without access to such facilities. Though the emergence of solar-powered cold storage technologies is particularly important in Tanzania, very little has been explored to understand how to improve access to these technologies for small-scale farmers experiencing high levels of postharvest food losses. This lack of research hampers government efforts to tackle the post-harvest food loss problem for high perishable food products, including fresh tomatoes. This study aims to examine barriers impeding the deployment and uptake of solar-powered cold storage technologies for tomato farmers in Tanzania and explore how state and non-state actors can intervene to improve access to such facilities for off-grid farming communities in Tanzania and beyond. The results show that the deployment of solar-powered cold storage technologies is constrained by limited awareness, high investment costs, low-paying capacity among farmers, and consumer preference for non-refrigerated foods. Findings also reveal that addressing many of the barriers identified demands promoting policies and programs that will attract and retain investment in solar-powered cold storage technologies, improving technology affordability through flexible payment arrangements, and increasing public awareness of the financial and environmental benefits of adopting solar-powered cold storage technologies. The study concludes that with adequate government support coupled with a favorable policy environment, small-scale farmers in Tanzania can widely adopt solar-powered cold storage technologies.

abstract: PhD


title: Understanding Team-Based Primary Care for the Management of Low Back Pain

contributor:
Miller, Jordan
Rehabilitation Science

subject:
Low Back Pain
Primary Care
Interprofessional
Health Services
Qualitative Research

abstract: Low back pain (LBP) is a leading contributor to disability, high healthcare costs, and is one of the most common reasons for primary care visits. Calls to action emphasize a need to move away from biomedically focused and fragmented care models for LBP. Quality standards also recommend that patients with chronic LBP have access to interprofessional care. However, patients with LBP often receive fragmented care that is biomedically focused and access to interprofessional care remains a challenge. Team-based models of primary care may offer a solution. Team-based models of primary care include family physicians and/or nurse practitioners, as well as other healthcare providers, such as pharmacists, occupational therapists, physiotherapists, and social workers. Despite an expansion of team-based models of primary care across Canada and internationally, there are gaps in knowledge on the management of patients with LBP within this practice setting. The overarching aim of this dissertation was to advance knowledge on current and innovative approaches to team-based primary care for the management of patients with LBP. It includes the results of three inter-related interpretive description qualitative studies. The first study sought to understand experiences accessing care within team-based models of primary care among adults living with chronic LBP. The second study sought to understand healthcare providers’ experiences, perceived barriers and facilitators, and recommendations for providing team-based primary care for the management of chronic LBP. The third study sought to understand the perspectives of patients and primary care team members related to their experiences with an innovative team-based model of primary care where a physiotherapist was available as a first point-of-contact for patients with LBP. The results demonstrate that team-based models of primary care can contribute to positive patient and healthcare provider experiences and that these care models may improve patient access to integrated interprofessional care that is guideline adherent. However, opportunities remain to optimize care delivery in these contexts. The results have implications for future research and practice innovations aimed at improving the quality of care, experiences, and health outcomes of patients with LBP within team-based primary care settings.

abstract: PhD


title: A Morse Index-Maslov Index Theorem for Discrete Lagrangian Systems

contributor:
Offin, Daniel
Mathematics and Statistics

subject:
Morse theory
Maslov index
billiards
dynamical systems
discrete mechanics
lagrangian mechanics
hamiltonian mechanics
symplectic geometry

abstract: We develop a discrete analog to Morse theory for discrete Lagrangian systems, including a discrete Morse index theorem and a correspondence theorem between the Morse indices of critical trajectories in discrete Lagrangian systems and the Maslov index of symplectic paths arising in associated discrete linear Hamiltonian systems. We use this correspondence to adapt criteria for linear stability of periodic trajectories in Lagrangian dynamics to this discrete setting. Finally, we apply some of these results to dynamical billiards.

abstract: PhD


title: Limit States Evaluation of a Modular Polymer Stormwater Collection Structure with Full-Scale Physical Modelling

contributor:
Brachman, Richard
Civil Engineering

subject:
Soil-structure interaction
Stormwater collection structure
Thermoplastic
Modular system

abstract:
Full-scale physical modelling was conducted to identify and evaluate limit states of a modular, polymer stormwater collection structure for shallow and deep burial cases. At minimum soil cover and when subjected to short-term design-truck loads, columns located directly beneath the load pad experienced the largest increments in force and the four central columns carried on average 31% of the applied nominal design truck load. Column demand at the factored service design truck load of 107 kN was equal to 0.45 and 0.64 times the single-column buckling resistance of the 0.6-m and 0.9-m-long columns tested. The columns as tested were found to satisfy load and resistance factor design requirements against short-term column buckling with a resistance factor of 0.7.  An ultimate limit state to surface load with shallow cover was reached at surface loads between 218 and 238 kN. Failure was governed by top platen rupture and central column buckling for the longer columns and by platen rupture for the shorter. No structural limiting state was reached when a parked vehicle load of 89 kN was sustained for one week and column compression increased by less than 20%.
The short-term lateral response along the edge of the structure during backfilling and under maximum burial were quantified using different soil materials, compaction methods, and column lengths. Tensile strains in edge columns were induced by lateral bending from soil placement and lateral earth pressures. Of the conditions tested, rammer-compacted poorly-graded gravel resulted in the largest short-term edge column tensions; however, even these values were 4.5 times smaller than the measured short-term strain limit. Physical modelling with elevated pressure and elevated temperature was then used to examine the buried system response subjected to vertical and lateral deep burial loading to infer longer-term behaviour.  Similar modes and magnitudes of deformation were found between elevated pressure and elevated temperature including large lateral bending of the edge columns and column bending strains that developed in the columns away from the edge. Predictions from the elevated temperature results tend to indicate a stable long-term response – provided material resistance remains the same as tested, based on extrapolations in time at lower temperatures in what may be the first application of the stepped isothermal method to a full-scale soil-structure system. The prediction method appears to be promising and was proved to not be invalid, as requirements of having smooth and continuous master curves and time shift factors that followed an Arrhenius relationship were satisfied.

abstract: PhD


title: Characterization and Classification of Ambient Seismic Noise in Urban Environments

contributor: Geological Sciences and Geological Engineering

subject:
ambient seismic
noise
unsupervised clustering
smart city
urban geophysics

abstract: This thesis presents the characterization and classification of ambient seismic noise in urban environments. Urban ambient seismic noise refers to the coherent seismic signal that comes from uncontrolled, or passive sources such as natural (e.g., wind, water waves, tides) and anthropogenic sources (e.g., traffic, pedestrians, machinery). Continuous urban ambient seismic monitoring can track citizen activities such as vehicle and pedestrian traffic, informing municipal planners and policymakers of how the urban environment is being used. As the proportion of the world population residing in urban environments increases, the applications of urban ambient seismic noise detection and monitoring grow. This is particularly evident in the emergence of smart city infrastructure that expands to bring together new types of sensors for monitoring. However, it is challenging to achieve coherent acquisitions due to the spatial, temporal, and spectral characteristics unique to urban environments, therefore new methods for characterization and classification are sought. An event detection workflow for characterizing ambient seismic noise using a pair of Tromino3G+ seismographs is presented, identifying coherent peaks in amplitude in time-frequency space as seismic events. Each event is defined by an amplitude, frequency, source azimuth, duration, and bandwidth. The workflow is applied to ambient noise acquisitions in an urban park environment, characterizing three major groups of events according to their seismic source. Recommendations are made regarding seismograph sampling frequency, sensitivity, and location at the site to inform a potential future long-term seismic monitoring system. The event detection workflow is also applied to a long-term (multi-day) and a short-term (20-minute) datasets in a residential area near a university campus. An unsupervised clustering workflow is applied to the event datasets to find similarities between events to establish an urban seismic noise baseline characterization. The clustering workflow is applied on an ambient seismic noise dataset acquired during a large pedestrian gathering (Queen’s University Homecoming celebrations) and results show that the anomalous activity is detectable using the developed procedure, making unsupervised clustering an effective technique for seismic noise classification. Both the event identification and unsupervised clustering workflows contribute to urban monitoring efforts, optimizing survey design and the interpretation of ambient seismic noise.

abstract: M.A.Sc.


title: Effects of Soil Cover, Water Table Elevation, and Erosion Voids on the Live Load Response of Corrugated Steel Culverts

contributor:
Moore, Ian
Hoult, Neil
Civil Engineering

subject:
culvert
shallow cover
erosion voids
water table elevation
full-scale experiment
live loading
distributed strain
2D finite element analysis
design codes

abstract: This thesis investigates the structural behaviour of corrugated steel pipe culverts under simulated vehicle loading with a focus on developing a better understanding of the effects of shallow burial depths, erosion voids, and water table elevation on the live load response. A horizontal ellipse culvert was tested under single wheel pair loads at 6 different burial depths ranging from 0.1 m to 1.2 m. The culvert’s strain response (measured with fibre optic sensors) was used to calculate the experimental bending moment and thrust responses around the circumference, which revealed that the structure’s bending moment response was consistently the dominant live load response, rather than the thrust at all burial depths. The results of this experiment were then compared to the bending moment and thrust responses estimated using the current Canadian and American bridge design standards, as well as the responses estimated using CANDE-2019 (a commonly used finite element analysis package). The comparison indicated that the Canadian code and CANDE-2019 were the most effective methods for estimating the culvert’s bending moment response under shallow burial conditions. To study the effects of erosion voids, the Deep Burial Simulator facility at Queen’s University was modified to allow for a water table to be established within the pit. This permitted an experimental study where erosion voids developed adjacent to a circular corrugated steel pipe due to water and soil infiltration into the structure through perforations created at the haunch positions. The results suggest that erosion voids lead to a greater change in the bending moment response under simulated vehicle loading compared to the thrust response, and this can also cause the location of the peak moment response to relocate to the position adjacent to the erosion void. A second experiment was also conducted in this facility, which involved applying simulated vehicle loads to the surface above the corrugated steel pipe with air-dried soil conditions, high water table conditions (with a phreatic surface 0.6 m above the crown), and low water table conditions (where the phreatic surface was lowered back to the invert). The results indicate that high water table conditions caused a significant reduction in the soil modulus compared to the other two water table scenarios, which led to approximately two times higher peak bending moments with high water table conditions versus the other two scenarios.

abstract: PhD


title: A Superlacunary Ito-Kawada Theorem, and Applications to the Equidistribution of Generalized Rudin-Shapiro Polynomials

contributor:
Rodgers, Brad
Mathematics and Statistics

subject:
Random Walks
Rudin-Shapiro Polynomials
Compact Groups
Lie Groups
Lie Algebras
Lacunary Sequences
Superlacunary Sequences

abstract: The Ito-Kawada Theorem is a classical result in the theory of random walks on compact groups. It states that essentially the only obstruction to the equidistribution of a random walk with independent and identically distributed increment is if the support of the increments is confined to proper, closed subgroup of G, or a coset of a proper, closed, normal subgroup of G. We prove a version of the Ito-Kawada theorem for a class of weakly dependent random variables arising from superlacunary sequences. We then show that a conjecture of Doche about the even moments of generalized Rudin-Shapiro polynomials follows from a conjectured Ito-Kawada theorem for lacunary random variables.

abstract: M.Sc.


title: Lowering the Surface Energy and Boosting the Wear Resistance and Flexibility of Transparent Omniphobic Poss Coatings

contributor:
Liu, Guojun
Chemistry

subject: Omniphobic Coating Anti-smudge

abstract:
Transparent anti-smudge coatings have many potential applications. For applications on foldable smartphones these coatings should have simultaneously wear resistance and flexibility. These properties are normally mutually exclusive. These properties were achieved recently via the photoinduced cationic ring-opening polymerization of 3-glycidyloxypropyl polyhedral oligomeric silsesquioxane (GPOSS) grafted with the anti-smudge agent poly(dimethyl siloxane) (PDMS). While this was the first example of a hard and flexible anti-smudge coating, improvements to hardness/wear resistance, flexibility and surface energy were desirable.
Herein, efforts to improve POSS-based omniphobic coatings are described. The first study involves the use of perfluoroalkyl groups in GPOSS to lower the coating’s surface energy. A systematic study is conducted by comparing the hardness, flexibility, and de-wetting properties of GPOSS coatings containing either -CF2CF3 or -CF2(CF2)4CF3 at various concentrations as the anti-smudge agent. Coatings containing the -CF2(CF2)4CF3 moiety are more effective at reducing the surface energy without significantly reducing the hardness. This coating can also withstand tens of bending cycles while maintaining its anti-smudge properties.
In search of POSS coatings with a higher hardness and wear resistance, POSS consisting of two different polymerizable groups, specifically methacrylate (M) and glycidyl (G) groups, are prepared to give various GmMnPOSS compounds. In particular, m and n are 2, 4, or 6, respectively, and m + n = 8. These coatings are systematically studied to determine the optimized photoinitiator amounts and curing conditions before the optical transparency, hardness and flexibility are compared of the various POSS coatings. G2M6POSS offers the best balance between hardness and flexibility.
To improve outward flexibility of G2M6POSS, a flexible porous poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) scaffold is first prepared. This porous scaffold is filled with G2M6POSS to produce a transparent and highly flexible coating that also maintains a high hardness. To endow the highly flexible G2M6POSS/PVDF-HFP coating with anti-smudge properties, a long chain perfluorinated polyether is covalently bound to G2M6POSS. The final fluorinated composite coating achieves a lower surface energy than is achieved with the perfluoroalkyl chains. These coatings can already be utilized for many applications and the insight gained from these studies will facilitate further development of hard yet flexible anti-smudge coatings.

abstract: PhD


title: A Small Change Approach on Adiposity, Lean Mass, and Bone Mineral Density in Adults with Overweight and Obesity: A Randomized Controlled Trial

contributor:
Robert, Ross
Kinesiology and Health Studies

subject:
Obesity
Body Composition
Randomized Controlled Trial
Overweight
Adults
Bone Mineral Density
Lean Mass
Appendicular Lean Mass
Visceral Adipose Tissue
Dual X-Ray Absorptiometry
Imaging
Adipose Tissue
Lifestyle
Small Change Approach
Behavioural
Abdominal Obesity

abstract:
Efforts to manage obesity through weight loss on a global scale have not been successful as most adults are unable to sustain the major changes in behaviour required to maintain weight loss long term. Many institutions now recognize that weight gain prevention by making small adjustments to energy intake (~100 kcal/day) and expenditure (~100kcal/day) represents a feasible strategy to manage obesity and related co-morbidities. The purpose of this thesis was to determine whether small changes in physical activity and diet could prevent adverse changes in body composition over two years in adults with overweight and obesity.
Two-hundred and eighty-nine previously inactive participants were included in a secondary analysis of data derived from a three-year, single-centre, two-arm, longitudinal randomized controlled trial. Participants were randomized to a small change approach (SCA) (N=144) or usual care (UC) (N=145). The SCA participants were counselled to make small changes in diet and physical activity, while UC participants were asked to maintain their usual lifestyle. Adiposity, lean mass, and bone mineral density were measured by dual-x-ray absorptiometry.
The study found that changes in total adiposity were significantly greater in SCA than UC at 6 and 12 months but did not remain significant at 24 months (mean change SCA [SE] -0.8 [0.4] vs. UC -0.7 [0.4] kg; difference 0.06, 95% confidence interval (CI) -1.1 to 1.2). Changes in visceral fat were significantly greater in SCA than UC at 6 and 12 months but did not remain significant at 24 months (-0.04 [0.03] vs. 0.02 [0.03] kg; difference 0.06, 95% CI -1.5 to 0.3). Changes in lean mass or bone mineral density were not significantly different between groups at any time points. A small preservation of appendicular lean mass was observed in the SCA compared to UC at 6, 12, and 24 months (0.0 [0.1] vs. -0.3 [0.1], difference 0.26, 95% CI 0.0 to 0.5).
Overall, the findings of this thesis do not support the notion that the SCA is more effective than usual care for the prevention of gains in total and abdominal obesity or the preservation of lean mass and bone mineral density. Whether a SCA that incorporates frequent monitoring alone by health care professionals prevents increases in adiposity and preservations of lean mass in adults with overweight or obesity by comparison to usual care merits investigation.

abstract: M.Sc.


title: Long-Term Neuronal Effects Following Developmental Exposure to Low Levels of Persistent Organic Pollutants

contributor:
Reynolds, James
Neuroscience Studies

subject:
Methylmercury
Polychlorinated biphenyls
Organochlorine
Arctic contaminant mixture
Prenatal
Lactation
Developmental
Neurotoxicology
Immunohistochemistry
Digital image analysis
ImageJ
Neuronal
Neurodevelopment
Glutamic acid decarboxylase-67
Endothelial cell
Capillaries
Lipofuscin
Northern
Toxicant
Arctic
Mercury
Immunofluorescence
adult offspring
Persistent organic pollutant
Bergmann
rat
Sprague Dawley

abstract:
Introduction: Persistent organic pollutants (POPs) methylmercury (MeHg), polychlorinated biphenyls (PCBs), and organochlorines (OCs) are a significant problem in Arctic regions of Canada. The long-term impact of low-level developmental exposure to POPs on offspring is not clearly understood. The objective of the present thesis was to examine the long-term effects of low-level developmental exposure to POPs, alone or in mixtures, on selected markers of brain structure and function in the adult central nervous system (CNS).

Method: Pregnant Sprague Dawley rats were exposed to one of four toxicant exposure conditions (MeHg, PCB, MeHg+PCB, or MeHg+PCB+OCs) at levels scaled to produce comparable maternal blood levels reported in epidemiological studies (or corn oil (control). Offspring were exposed to the toxicants from gestational day (GD) 1 to postnatal day (PND) 21 and thereafter with no further toxicant exposures aged to late adulthood (PND 450). The brain of adult offspring was fixed, frozen, and slide mounted for processing using immunohistochemistry and immunofluorescence techniques. A battery of markers of brain structure and function were assessed (glutamic acid decarboxylase (GAD)-67, glial cells (microglia, Bergmann glia), cleaved caspase-3, cresyl violet, doublecortin, double-stranded DNA (Hoechst), tyrosine hydroxylase, rat-endothelial cell antigen-1, lipofuscin). Eleven neuronal regions were included in the analysis. Digital image analysis was performed (ImageJ). Independent Samples T-tests compared toxicant-exposed animals with controls.

Results: Most statistically significant observations were reported in neuronal regions localized in the brainstem. Across all four toxicant exposure groups (MeHg, PCB, MeHg+PCB, and MeHg+PCB+OC), a statistically significant increase in GAD67 was observed in the cerebellum, in comparison with controls. Likewise, a consistent decrease in lipofuscin autofluorescence was observed in the locus coeruleus in all toxicant-exposed offspring. Endothelial cell and capillary morphological marker RECA-1 was observed to be altered in a temporal manner with respect to neuronal development that corresponds to peak exposures to MeHg and PCBs. Toxicant mixtures (MeHg+PCB, MeHg+PCB+OC) resulted in comparatively fewer statistically significant changes in markers of brain structure and function than individual toxicant exposures (MeHg, PCBs).

Conclusion: Altogether, the present study suggests that prenatal and early post-natal exposures to low levels of POPs may have lasting, selective, region-specific effects upon the CNS.

abstract: PhD


title: Identifying Mental Health Issues In Canadian Immigrants With A Focus On Indian Immigrants

contributor:
Rosenberg, Mark
Aronson, Kristan
Public Health Sciences

subject:
mental health
immigrant health
healthy immigrant effect

abstract:
Purpose: The purpose of this study is to expand on current knowledge of the mental health of immigrants in Canada by identifying differences in self-rated mental health among immigrant groups based on immigration related, sociodemographic and health and healthcare access related characteristics.
Methods: Data from the 2015/2016 and 2017/2018 cycles of the Canadian Community Health Survey (CCHS), an annual cross-sectional survey disseminated by Statistics Canada, were accessed. Analysis includes descriptive statistics, and a bivariate analysis of each independent variable with the dependent variables. Three sets of series of logistic regression models were analyzed to assess associations between these variables and 1) self-reported mental health (good/poor); 2) reporting a mood disorder (no/yes); and, 3) having an anxiety disorder (no/yes).
Results: Results provide support for the healthy immigrant effect. Immigrating in later life and from a lower income country is advantageous for mental health. Living in urban areas, being white, having a higher income, not being under the age of 12 or over 65, are all associated with better mental health in immigrants.
Conclusions: Certain sociodemographic and immigration related characteristics put immigrants at risk of poorer mental health outcomes. Further research is necessary to further elucidate these relationships and how mental health supports can be targeted to those who may be at the greatest risk post immigration.

abstract: M.Sc.


title: Multi-component mass transfer of background dissolved gases and stray methane gas in shallow groundwater systems

contributor:
Mumford, Kevin
Civil Engineering

subject:
Multi-component mass transfer
Groundwater
Stray gas
Hydrogeology
Gas migration

abstract: The goal of this research was to investigate the effects of multi-component mass transfer between methane gas and background dissolved gases (e.g., nitrogen) to improve stray gas detection techniques and advance understanding of methane persistence following a repaired leak. This was achieved by conducting a series of gas injection experiments in a quasi-two-dimensional flow cell (40 × 39.6 × 1.15 cm) simulating an active gas leak and a post-repair scenario and developing simple single cell numerical models of the active (steady-state) leak and the post-repair (kinetic) dissolution. Experiments were conducted at two aqueous fluxes (3.8 m/day and 0.9 m/day) and two heterogeneities (pool- and finger-dominated source architectures). Dissolved oxygen was measured in the effluent water as a representative of background dissolved gases and light transmission techniques were used to quantify gas saturations. A steady-state model was developed to predict the mass transfer rate coefficient for each experiment and the changes in background dissolved gases under a range of conditions. A kinetic model was developed to predict the gas saturations and dissolved gas concentrations during post-repair dissolution, testing the sensitivity of mass transfer rate coefficients and single- and multi-component dissolved gases. Experiments showed that background dissolved gas detectability was highest at slow groundwater fluxes and in pooled source architectures. The steady-state model indicated that the detectability of background dissolved gases was proportional to the initial background dissolved gas concentration in the groundwater, however, the dissolved source gas concentrations remained relatively unchanged with depleted background dissolved gases. Experiments also showed that more time was required for background dissolved gases to return to baseline conditions post repair in pooled source architectures. Kinetic model simulations indicated that a constant mass transfer rate coefficient was sufficient to predict experimental data, as a transient mass transfer rate coefficient did not substantially improve the model fit. The kinetic model also demonstrated that gas persistence was longer in simulations that considered multiple dissolved gases compared to a single-component model. The findings of this study indicate that background dissolved gases may be a useful tool for stray gas detection and that gas persistence is influenced by multiple dissolved gases.

abstract: M.A.Sc.


title: Modulation of Spinal Afferent Neuronal Structure and Function in Diseases Associated with Abdominal Pain

contributor:
Lomax, Alan
Neuroscience Studies

subject:
IBS
Pancreatic cancer
Dorsal root ganglia
Abdominal pain

abstract:
Background: Abdominal pain is a primary symptom of many gastrointestinal diseases, including irritable bowel syndrome (IBS) and pancreatic ductal adenocarcinoma (PDAC).  Many mediators have been implicated in the pathophysiology of these diseases and the development of abdominal pain, a phenomenon whose main feature is its vague localization. Emerging therapeutic targets for IBS are changes in diet and the release of specific microbial mediators, which can trigger symptoms of pain. Additionally, neurotrophins of the GDNF family and their RET receptors have been implicated in the development of neural invasion by pancreatic tumor cells, a process which has been linked to abdominal pain and decreased survival in cancer patients.
Aims and Methodology: Patch clamp electrophysiology experiments were performed on DRG neurons incubated with fecal supernatant (FS) from IBS patients to determine the mechanisms behind a low FODMAP diet-microbiota interaction in the pathology of this disease. Retrograde tracing experiments were performed on C57Bl/6 mice using fluorescent neuron tracers to determine the extent of overlap in receptive fields of colon-projecting DRG neurons, a feature which can exacerbate and contribute to the vague localization of abdominal pain. Lastly, following treatment with conditioned media from PDAC cell lines (PanC1 and MiaPaCa-2) changes in DRG neuron morphology were quantified using Sholl analysis to determine if RET ligands released by PDAC cell lines have a neurotrophic effect on DRG neurons, facilitating neural invasion.
Results: Spinal afferent neurons become more excitable following treatment with IBS-D patient FS, and lowering FODMAP intake reduces pain severity and mitigates the excitatory effect of patient FS. The underlying mechanisms in FS-induced hyperexcitability is a decreased leak K+ conductance triggered by activation of PAR2 receptors via cysteine proteases. Retrograde tracing revealed dual-innervation of the proximal and distal regions of the colon by individual extrinsic afferent neurons. Lastly, RET ligands secreted by PanC1 and MiaPaCa-2 cell lines lead to increases in DRG neurite branching and length via RET receptor activation, an event which could facilitate the development of neural invasion.
Conclusion: Taken together, this data provides a more thorough understanding of the role of spinal afferent neurons in health and disease.

abstract: PhD


title: Quantitative Analysis of Genotype-to-phenotype Mappings in Evolutionary Algorithms

contributor:
Hu, Ting
Computing

subject:
genetic programming
genotype-to-phenotype mapping
robustness
evolvability

abstract:
The genotype-to-phenotype mapping is one of the definitive features of an evolutionary algorithm (EA). It determines how the genotypic variations can be translated to phenotypic improvements. Most genotype-to-phenotype mappings in EAs are redundant, i.e., multiple genotypes can map to the same phenotype. Phenotypes are accessible from one to another through point mutations. However, these mutational connections can be unevenly distributed among phenotypes. Quantitative analysis of such connections helps better characterize the genotype-to-phenotype mapping of an EA, and better understand the search ability of the algorithm.
In this thesis, we quantitatively characterize how genotypes map to phenotypes and how mutational connections distribute among phenotypes in linear genetic programming algorithms. We propose two genotype-to-phenotype mapping mechanisms, where the execution and output of a linear genetic program are controlled by a regulator. We investigate how such regulatory mappings can alter the mutational connections among different phenotypes. We also compare the search ability of LGP using the conventional mapping versus the regulatory mappings, and observe that the regulatory mappings improve the efficiency in all three search scenarios, including random walk, hill climbing, and novelty search.

abstract: M.Sc.


title: Robot Decision Making to Play a Tower Building Game

contributor:
Givigi, Sidney
Computing

subject:
Artificial Intelligence
Machine Learning
Decision Making
Collision Avoidance
Robots
Reinforcement Learning

abstract: Robots are becoming more integrated into society as they become more advanced, and the programming behind them needs to continue to progress in order for the robots to be utilized to their fullest potential. Artificial Intelligence (AI) is one of the most versatile and quickly growing areas of robotic control, and has been used for a variety of different robots and tasks. One potential use of robotics and AI is in that of childhood development. Cooperative play has been shown to be a crucial part of childhood development, and for children with developmental disabilities, playing with other children may be difficult and frustrating, leading them to miss out on this important milestone. Cooperative play with robots has been shown to have positive educational and therapeutic effects on children with developmental disabilities, and so robots can be used as substitute players for children who have troubles playing with other children. To achieve this, an AI must be developed that can make appropriate decisions or moves for a given game, to such an extent that the children would choose to play with the robot instead of alone. This will require both high-level decision making, for deciding on the move to use, and low-level motion planning, to actually carry out the move in the real world. Both of these parts can be carried out by AI agents, which can work together to produce an AI system capable of reasoning and intelligent decision making with respect to a game. In this thesis three AIs and two algorithms will be developed to play Menara, a cooperative tower building game. The three AIs include the low level motion planning agent, the high level pillar placement agent, and the high level tile placement agent. The algorithms include the method for selecting the pillars to have available to the agent during gameplay, and how many pillars the agent plans to place in a single turn. The low level agent, trained first with collision checking only at the final location of a step, then with continuous collision checking, performed reasonably well, achieving a final success rate of 85\%. The high level tile placement agent was able to successfully balance a tile 62\% of the time, while the high level pillar placement agent was able to succeed 79\% of the time on the test dataset.

abstract: M.Sc.


title: The Effects of Outdoor Air Pollution on Inflammation and Preeclampsia

contributor:
King, Will D
Borghese, Michael M
Villeneuve, Paul J
Public Health Sciences

subject: epidemiology

subject: biostatistics

subject: PM2.5

subject: NO2

subject: O3

subject: pregnancy

subject: preeclampsia

abstract:
Background: Outdoor air pollution is a ubiquitous and deleterious environmental exposure, and its relationship with several chronic diseases and acute health outcomes is well established. Outdoor air pollution is also associated with pregnancy complications such as preeclampsia. PM2.5, NO2, and O3 are some of the most commonly studied air pollutants, and can influence important biological processes in pregnancy, such as inflammation.

Methods: This thesis explored different aspects of the relationship between air pollution and inflammation, and air pollution and preeclampsia. In Component 1, effects between PM2.5 and NO2 with four inflammation biomarkers (C-reactive protein, interleukin-6, interleukin-8, tumour necrosis factor-α) during pregnancy were assessed. In Component 2, the multipollutant effects of PM2.5, NO2, and O3 as a mixture on C-reactive protein were assessed, with consideration of surrounding green space as a confounder or effect modifier. In Components 3 and 4, a dose-response meta-analysis and burden of disease analysis were conducted, respectively. The Maternal Infant Research on Environmental Chemicals birth cohort was used for nested analyses for Components 1 and 2. Component 3 used publicly available data from previously published studies, and Component 4 used ecologic measures of PM2.5. Statistical methods included linear regression, restricted cubic splines, and mixture methods in Components 1 and 2, and dose-response meta-analyses, and burden of disease analyses in Components 3 and 4.

Results: In Components 1 and 2 a consistent relationship between PM2.5 and C-reactive protein, an important inflammation biomarker was observed. In Component 2 specifically, the relationship between a mixture of PM2.5, NO2, and O3 was stronger then when compared with individual pollutant effects. In the meta-analysis for a relationship between PM2.5 and preeclampsia, the summary RR estimate was 1.07 (95% CI: 0.99-1.15) per 10μg/m3 average increase in PM2.5, which was lower than previously published estimates. In burden of disease calculations, it was estimated that PM2.5 is responsible for 4.8% of preeclampsia cases in Canada.

Discussion: This thesis adds to the literature on the relationship between air pollution and preeclampsia by elucidating on a biological mechanism through which PM2.5 might increase risk of preeclampsia, and providing summary burden of disease estimates for the relationship between PM2.5 and preeclampsia. The work highlights the importance of studying environmental exposures in pregnancy, and contributes to the understanding of inflammation as a mechanism through which PM2.5 might impact preeclampsia incidence.

abstract: PhD


title: Placental epigenetic modifications and development in valproic acid-induced teratogenesis

contributor:
Winn, Louise
Biomedical and Molecular Sciences

subject:
Valproic acid
epigenetic
teratogen

abstract: Valproic acid (VPA) is an anti-epileptic and a teratogen. In utero exposure to VPA is associated with congenital malformations and neurodevelopment disorders. VPA exerts its teratogenic effects through epigenetic dysregulation, which interferes with tissue development and function. Evidence suggests that VPA can also cause placental toxicity, which may serve as an important mechanism of VPA-induced teratogenicity. The purpose of this thesis was to investigate the effect of VPA on placental epigenetics, as well as placental growth and development, in the CD1 mouse model. We exposed pregnant mice to 600 mg/kg of VPA or saline on GD13 and collected placental tissues at 1, 3 and 24 h post-dosing, to characterize the profile of histone modifications and measure DNA methylation levels. Moreover, we exposed pregnant mice to 600 mg/kg of VPA or saline on GD9 or GD13 and collected placental and fetal tissues on GD18, to assess placental growth and development as well as fetal survival and viability. We found that exposure to VPA on GD9 significantly decreased placental weight and caused a pronounced expansion of the placental labyrinth layer following maternal exposure in CD1 mice; these results were accompanied by an increased number of resorptions, as well as exencephaly and growth restriction in VPA-exposed pups. We suspect defective placental vascularization as a possible mechanism of teratogenicity observed from VPA exposure on GD9. Exposure to VPA on GD13 significantly decreased placental weight and increased the number of resorptions but had no effect on placental tissue layer development or fetal growth. Analysis of epigenetic modifications in the GD13 placenta revealed that VPA significantly increased histone H4 acetylation and H3K4 di-methylation at 1 and 3 h post maternal dose, though had no effect on DNA methylation levels. These results demonstrate that VPA interferes with placental growth and development, and elicits histone modifications, which may a vital role in VPA-induced teratogenicity.

abstract: M.Sc.


title: Experimental and Theoretical Investigations of a New Flat Slab System Incorporating GFRP Stay-In-Place Structural Forms and Embedded I-Beams

contributor:
Fam, Amir
Genikomsou, Aikaterini
Civil Engineering

subject:
Stay-in-place forms
Reinforced Concrete
Finite Element Analysis
Digital Image Correlation
Punching Shear
GFRP
Two-way slabs
Structural form
Bond
Embedded beams
Flat slab
Connections
Shear reinforcement

abstract:
A novel steel-free concrete flat-slab design for floors is introduced. It includes embedded glass fiber-reinforced polymer (GFRP) I-sections as primary and secondary beams, with columns supporting the primary beams. GFRP stay-in-place (SIP) structural forms span the spacing between, and are bonded to, the lower flanges of the I-beams. Different components of the floor were investigated. Flexural behaviour in the direction transverse to the I-beams was investigated in the positive and negative moment regions using 2,575×610×225 mm slab segments, incorporating bonded connections and away from connections. A design-oriented analytical model was developed to predict connection strength based on bond failure. A case study of a floor design was presented and met the strength requirement. A nonlinear finite element analysis with emphasis on the flexural behaviour in the two orthogonal directions, namely transverse and parallel to the I-beam was also carried out. It incorporates appropriate interfacial and contact relations and robust failure criteria of the constituents. The model was verified against experimental results and used in a comprehensive parametric study.
Punching shear behaviour of the slab was investigated using four full-scale interior slab-column specimens, 2000x2000x200 mm, tested under axial compression applied to the column. The study assessed the contributions of different components of the GFRP system. The new design experienced a 29% higher punching shear strength than a control slab with GFRP top rebar only, and an increase in ductility index from 1.6 to 3.1. An analytical model was developed, accounting for concrete contribution and flexural and web contributions of I-beams. Results agreed with experimental punching shear strength, within -6 to +13%, and a parametric study was carried out.
A special emphasis was placed on the bonded connection between SIP forms and I-beams, being the weakest link in the system. Bonded connections of different types and configurations were examined through 48 bond specimens tested in tension. Digital Image Correlation (DIC) was used to capture strain and slip profiles along the interfaces, from which shear and peeling stress distributions were established. The connections reached 80-100% of the full capacity of the member, governed by the transverse tensile strength of the I-beam. The two highest occurrences were fiber-tear of the SIP form and adhesive failure. The combined test data was used to establish the shear-peeling stress interaction failure envelope and a bond-slip relationship.

abstract: PhD


title: Examining the Impact of Housing Conditions on Depression-Like Responses in Rats

contributor:
Menard, Janet
Psychology

subject:
depression
animal research
housing
welfare

abstract: Part of the increasing attention to improving animal welfare includes the shift to individually-ventilated cages (IVCs). There is some evidence that housing animals in IVCs is inherently stressful, which could impact the outcome of preclinical research and would therefore benefit from more in-depth study. Consequently, the purpose of my thesis is to determine if extended housing of rats in IVCs influences the development of depression-like outcomes to a greater extent than conventional, open-top cages (OTCs) and to determine if these outcomes are impacted by social housing. My hypotheses were: that IVC rats would show more depression-like responses than OTC rats and that single-housed rats would show more depression-like responses than pair-housed rats.  I also expected a cage type by social housing interaction such that the differences in depression-like responding between single and pair-housed animals would be reduced in the IVC condition relative to the OTC condition. To test the rats’ depression-like behaviours, I used the forced swim test and the splash test. To test for changes in physiology related to depression, I weighed each animal’s adrenal glands post-mortem. In the splash test, as expected, I found that IVC rats took longer to begin grooming than OTC rats, and that IVC rats showed fewer grooming bouts than OTC rats. However, unexpectedly, single-housed rats showed more grooming bouts and longer grooming time than pair-housed rats. In the forced swim test, the results did not follow my predictions. Instead, IVC and single-housed rats spent less time immobile than OTC animals and pair-housed animals, respectively. However, the decreases in immobility appeared to be secondary to increases in escape-like behaviour (i.e., climbing and diving). My results indicate that IVC-housed rats did not show more depression-like outcomes than OTC rats. However, the behaviour shown may be explained by increased anxiety-like responses in the IVC rats. Overall, it appeared that the behavioural profiles displayed by IVC-housed rats and single-housed rats were indicative of greater anxiety-like behaviour as opposed to depression-like behaviour.

abstract: M.Sc.


title: Describing protostellar disk structure in Ophiuchus

contributor: Physics, Engineering Physics and Astronomy

subject:
Astronomy
Physics
Protostellar disks

abstract: Young forming stars host circumstellar disks of dust and gas. High-resolution, millimeter observations of disks at the protoplanetary stage reveal substructures such as gaps, rings, arcs, spirals, and cavities. These structures are often attributed to disturbances from young, newly formed planets or mechanisms conducive to planet formation. However, the formation mechanisms of the substructures are unconstrained, and only a few disks at the younger protostellar stage have known substructures to date. In this thesis, we present a detailed analysis of 1.3 and 0.87 mm observations of ten protostellar disks in the Ophiuchus star-forming region in a search for the origins of the substructure. Of the sample of ten, four disks have identified structure, three are smooth disks, and three are ambiguous. The structured disks have wide Gaussian-like rings (σR/Rdisk ∼ 0.26) above a smooth disk profile with low contrasts (C < 0.2) in comparison to protoplanetary disks where the rings are narrow and have a wide variety of contrasts (σR/Rdisk ∼ 0.08 and C ranges from 0 − 1). These structured protostellar disks are the brightest sources in the Ophiuchus sample, in agreement with trends observed for protoplanetary disks, and two show evidence of flaring, indicating large dust grains have not had time to fully settle onto the midplane of the disk. These observations indicate that structure in protostellar disks may be common. The presence of structure at the earliest stages suggests an early start for dust grain growth and, subsequently planet formation.

abstract: M.Sc.


title: Structural Performance of Cast-In-Place Pipe Liners at Perforations and Ring Fractures in the Host Pipe

subject:
CIPP
FEA
Pipe Rehabilitation

abstract:
The objective of this research project is to evaluate the structural performance of Cast-In-Place Pipe (CIPP) liners for pressure pipes, around areas of deterioration in the host pipe, specifically perforations and ring fractures.
To evaluate the liner behaviour around perforations in a host pipe, an investigation using finite element analysis (FEA) was undertaken. The constructed FEA model was evaluated against data from previous physical experiments conducted on CIPP lined metal pipes with idealized circular perforations, and the model was improved iteratively. It was found that the model was capable of capturing peak strains but failed to properly estimate the strain distribution at the edge of the perforation. The new FEA model was then used to investigate the behaviour of CIPP liners spanning across oval shaped perforations. The FEA simulation showed that the oval shaped perforation with long diameter of 50 mm and short diameter of 25 mm has strain readings that are in-between the strain readings of 25 mm and 50 mm circular perforation.
Secondly, a series of full-scale physical experiments were undertaken to develop procedures for testing CIPP rehabilitated pipe samples with a ring fracture under pure axial tension. A set of two lined specimens with idealized ring fractures were designed, fabricated and were used to evaluate the testing procedure. Distributed Fibre Optic Sensing (DFOS) were used to monitor the strain change in the liner throughout the loading process in an attempt to estimate the debonded length of the liner. A special instrumentation method was designed and utilized to install the fibre optic cables onto the sample due to physical constraints. Two experiments were conducted: an Unpressurized test and a Pressurized test. The Unpressurized test results indicated that the debonded length of the liner was much shorter than predicted with closed-form solution due to better than expected adhesion between the liner and the pipe. Similar results were seen in the measured gap opening for the Pressurized pipe. A number of challenges meant that neither test was able to fully capture the behaviour of the lined system but recommendations for future improvements will enable further work to investigate this behaviour.

abstract: M.A.Sc.


title: Total Hip Arthroplasty versus Hemiarthroplasty for Femoral Neck Fracture: Propensity-Score Matched Cohort Study and Survey of Orthopaedic Surgeons in Ontario

contributor:
Groome, Patricia
Mann, Stephen
Public Health Sciences

subject:
Total hip arthroplasty
Hemiarthroplasty
Hip fracture
Comparative effectiveness research
Femoral neck fracture
Propensity score analysis
Population-based study
Survey
Orthopaedic Surgery
Practice variation

abstract:
Background
There is significant variation in treatment of displaced femoral neck fractures in older patients and ongoing controversy regarding optimal treatment.

Methods
This thesis examined surgical practice variation in the use of total hip arthroplasty (THA) versus hemiarthroplasty for femoral neck fracture and compared clinical outcomes across a matched group of patients who underwent either procedure. We linked healthcare databases at ICES to create a population-based cohort of 49,597 patients aged 60 years and older who underwent hemiarthroplasty or THA for femoral neck fracture between 2002 – 2017. We used multilevel logistic regression modeling to quantify the association between patient-, surgeon-, and institution-level variables and treatment with THA. We compared clinical outcomes in a subset of propensity-score matched patients using survival analysis.
We developed, tested, and administered a survey to orthopaedic surgeons in Ontario to better understand the reasons underlying this treatment variation. We used a vignette-based experimental design and multilevel and multivariable linear regression modeling to determine factors associated with treatment recommendation.

Results
9.4% of cohort patients (n=4,638) were treated with THA. Treating surgeon and institution accounted for most of the treatment variation. Patient factors associated with THA included: younger age, male sex, lower comorbidity burden, and rheumatoid arthritis. Long-term care residence, use of home care services, dementia, and marginalization were negatively associated with THA. Patients treated with THA had higher risk of hip dislocation at two years post-operation. Risk of revision was similar between treatment groups at 30 days, one year, and two years post-operation.

Our survey response rate was 61.1% (n=302), and 60.3% of surgeons practiced in the community. Surgeon-level predictors of treatment with THA included: higher volume of THA for fracture, elective THA practice, and increasing years in practice. Pre-existing hip arthritis increased likelihood to recommend THA, while increasing patient age and comorbidity burden decreased likelihood to recommend THA.

Conclusion
There is significant treatment variation at the patient-, surgeon-, and institution-levels for patients undergoing arthroplasty for femoral neck fracture in Ontario. Shared decision making should involve discussion of increased risk of short-term hip dislocation with THA.

abstract: PhD


title: The (Im)precise Promise of Precision Medicine: Sickle Cell Disease, Race and Artificial Intelligence in Health Care

contributor:
Stinson, Catherine
Philosophy

subject:
Bioethics
AI Ethics
Sickle Cell Disease
Racism
Racism in Health Care
Race Science
Race Medicine

abstract:
Precision medicine (PM) is an emergent technology and method of disease treatment and prevention that considers the genes, environment, and lifestyle of each person it seeks to treat. PM promises to generate more accurate and personalized treatment to improve a person's health outcomes. The ethical considerations of PM technologies warrant further investigation to ensure that its promises are not going to be flawed for certain populations. To evaluate whether the promises of PM will be met, and to better understand the kinds of diseases that these technologies seek to treat in the first place, this paper interrogates sickle cell disease (SCD) and new promising PM-enabled treatments for the disease.
The objective of this paper is to understand the social, economic, political, and racialized context in which SCD is understood and similarly the social, economic, political, and racialized context in which PM is to be implemented and to evaluate whether the promises of PM can be guaranteed for all populations, especially racialized populations. In this paper and based on a consideration of the many factors that determine health outcomes, I argue that the health- related promises of PM will cannot be met unless a complete understanding of illness, disease and their contributing factors become integral to the technology and its implementation. Finally, I look to historical accounts of Black activism with enthusiasm to show what precision medicine should look like and how its promises could be achieved for all populations, especially Black populations.

abstract: M.A.


title: KDK measurements of direct-to-ground-state electron captures in Zinc-65 and Potassium-40

rights: Attribution-NonCommercial 3.0 United States

subject:
particle physics
nuclear physics
rare decay
beta decay
dark matter
direct detection
geochronology
neutrinoless double-beta decay
rare event search
silicon drift detector
modular total absorption spectrometer
nuclear theory
nuclear structure
electron capture
forbidden decay
unique decay
weak axial-vector coupling

abstract: M.Sc.


title: "It's not just about petting horses": Understanding Equine-Assisted Psychotherapy and Horse-Human Healing Relationships

contributor:
King, Samantha
Kinesiology and Health Studies

subject:
equine-assisted psychotherapy
horse-human relationships
animal labour
professionalization
epistemology
spirituality
animal identity

abstract:
This thesis critically analyses experiences of the horse-human relationship in equine-assisted psychotherapy (EAP). As a therapeutic modality, EAP relies on the presence of a horse, a licensed psychotherapist, and a client. As the field is generally unregulated, each EAP session and practice is slightly different. Drawing on interview data conducted with 10 Ontario-based EAP clinicians, I offer two main arguments: First, I demonstrate that psychotherapists approach the horse-human relationship differently depending on how they understand the role of their horse in the EAP encounter. Clinicians often anthropomorphize, or assign human-like characteristics to their horses, as a way of respecting the work that they do in an EAP session. Other clinicians believed that EAP horses are ‘just horses,’ interacting with clients based on their evolutionary
programming as prey animals. A select few psychotherapists blurred the species boundaries between horses and humans further, by likening their clients to their horses and effectively animalizing them in the process of comparison. I argue that this third approach has the most potential to help EAP clients, clinicians, and horses enter into respectful relationships that may allow for mutual flourishing. Second, I demonstrate the epistemological tensions at the heart of EAP practice. Because EAP may be considered a complementary or alternative medicine, clinicians often feel that they are not adequately recognized by the general public or by other healthcare professionals for the work they do and shared that they would like to see further professionalization of the field via training requirements and consistency in accreditation. While this alignment with biomedical legitimacy is welcomed by some, it may be incongruous with the holistic, client-centered, and sometimes spiritual components of EAP that sets it apart from traditional, biomedically recognized talk therapies. I argue that the spiritual element of EAP is at odds with the dominant Western scientific paradigm, which could be lost should EAP undergo professionalization and further standardization and regulation. I conclude by offering several areas for further exploration and reflect on the challenge of centering animals in critical research when they are not directly present in data collection.

abstract: M.A.