title: Three Essays on Health and Health Behaviours of Immigrants

contributor:
Sweetman, Arthur
Economics

subject: Immigrats

subject: Healthcare utilization

subject: Language proficiency

subject: Medical Expenses Tax Credit (METC)

subject: Refundable Medical Expenses Supplement (MES)

subject: Age at migration

subject: Years since migration (YSM)

subject: Non-immigrants

abstract:
This thesis focuses on the comparison between immigrants and non-immigrants with respect to various health-related behaviours perspective/viewpoints. Specifically, this thesis comprises three essays. First, I investigate any differences in the factors for utilizing general practitioners (GP) and specialists (SP) between immigrants and non-immigrants in Canada. Second, I examine the causal effects of language proficiency on the health and health behaviours of immigrants to Canada. Finally, I investigate whether there are any differences in the claiming patterns of the Medical Expense Tax Credit (METC) and/or Medical Expense Supplement (MES) for immigrants compared to non-immigrants in Canada.

Chapter 1 investigates any differences in healthcare utilization patterns between immigrants and non-immigrants. We implement a two-part model, where the first part applies logistic regressions to assess factors associated with visiting a physician, and the second applies zero-truncated negative binomial regression models to capture the frequency of using healthcare services, conditional on having at least one visit. Our results show that the patterns of healthcare utilization are different for immigrants compared to non-immigrants; differences are also observed by gender and age. More specifically, prescription drug insurance coverage and chronic conditions play opposing roles for male and female immigrants compared to their non-immigrants counterparts. Moreover, the number of years since migration is an important factor in increasing the probability of any general practitioner (GP) and specialist (SP) visit for all immigrants.

Chapter 2 is to my knowledge, the first research on the causal effects of language proficiency on health outcomes and healthcare utilization of immigrants in Canada. My finding contradicts the idea that immigrants with poor language facilities are less likely to have a regular doctor. I find that good self-reported health is positively associated with language proficiency. However, I find no statistically significant causal effect of language proficiency on reporting ‘good mental health’. In addition, I find strong evidence that the utilization of hospital and mental health care services are positively associated with being English-language proficient even after controlling for many possible sets of factors.

Chapter 3 contributes by supporting existing literature, but with a completely different dimension: the medical tax perspective. I am unaware of any previous research that directly compares the claim patterns of the Medical Expense Tax Credit (METC) and/or refundable Medical Expense Supplement (MES) for immigrants with those of non-immigrants in Canada. My results show that there are differences in the proportions of tax filers who claimed the METC and/or MES, and the amounts of a claim for the METC and/or MES for immigrants compared to non-immigrants; differences are also observed by age, years since migration (YSM), province and immigration categories. In both couples and single families, a lower proportion of immigrant tax filers claimed gross immediate family medical expenses (GME), potential METC claims, and METC refunds compared to non-immigrants. In the case of single families, a higher proportion of non-immigrant tax filers claimed MES compared to their immigrant counterparts.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Automated Monitoring for Data Center Infrastructure

contributor:
Zheng, Rong
Computing and Software

subject: Green Data Center, Environmental Monitoring, Internet of Things

abstract:
Environmental monitoring using wireless sensors plays a key role in detecting hotspots or over-cooling conditions in a data center (DC). Despite a myriad of Data Center Wireless Sensor Network (DCWSN) solutions in literature, their adoption in DCs is scarce due to four challenges: low reliability, short battery lifetime, lack of adaptability, and labour intensive deployment. The main objective of this research is to address these challenges in our specifically designed hierarchical DCWSN, called Low Energy Monitoring Network (LEMoNet).
LEMoNet is a two-tier protocol, which features Bluetooth Low Energy (BLE) for sensors communication in the first tier. It leverages multi-gateway packet reception in its second tier to mitigate the unreliability of BLE. The protocol has been experimentally validated in a small DC and evaluated by simulations in a midsize DC. However, since the main application of DCWSNs is in colocation and large DCs, an affordable and fast approach is still required to assess LEMoNet in large scale. As the first contribution, we develop an analytical model to characterize its scalability and energy efficiency in a given network topology. The accuracy
of the model is validated through extensive event-driven simulations. Evaluation results show that LEMoNet can achieve high reliability in a network of 4800 nodes at a duty cycle of 15s.
To achieve the network adaptability, we introduce and design SoftBLE, a Software-Defined Networking (SDN) based framework that provides controllability to the network. It takes advantages of advanced control knobs recently available in BLE protocol stacks. SoftBLE is complemented by two orchestration algorithms to optimize gateway and sensor parameters based on run-time measurements. Evaluation results from both an experimental testbed and a large-scale simulation study show that using SoftBLE, sensors consume 70% less power in data collection compared to those in baseline approaches while achieving the Packet Reception Rate (PRR) no less than 99.9%.
One of its main steps of DCWSN commissioning is sensor localization, which is labour-intensive if is driven manually. To streamline the process, we devise a novel approach for automated sensor mapping. Since Radio Frequency (RF) alone is not a reliable data source for sensor localization in harsh and multi-path rich environments such as a DCs, we investigate using non-RF alternatives. Thermal Piloting is a classification model to correlate temperature sensor measurements with the expected thermal values at their locations. It achieves an average localization error of 0.64 meters in a modular DC testbed. The idea is further improved by a multimodal approach that incorporates pairwise Received Signal Strength (RSS) measurements of RF signals. The problem is formulated as Weighted Graph Matching
(WGM) between an analytical graph and an experimental graph. A parallel algorithm is proposed to find heuristic solutions to this NP-hard problem, which is 30% more accurate than the baselines. The evaluation in a modular DC testbed shows that the localization errors using multi-modality are less than one-third of that of using thermal data alone.

abstract: Thesis

abstract: Candidate in Philosophy


title: Care in Custody: An Ethnography of Illness and End of Life in Prison

contributor:
Badone, Ellen
Goldfarb, Kathryn
Anthropology

subject:
prison
ageing in prison
terminal illness
end of life
prison health care
prison hospice
medical anthropology
prison ethnography

abstract: This thesis presents an ethnographic study of the experiences of men living with and dying from serious illness in prison, with a particular focus on the kinds of care they receive and the ways in which they experience that care. The dissertation draws on extensive ethnographic fieldwork conducted over two years in U.S. state prisons in Maine, presented in three standalone papers. The first paper outlines how the prison and its health care system shape the illness experiences of older and ageing prisoners and asks, what does it mean when the lives of prisoners collide with contracted for-profit medical care and how might their lives be constituted as unworthy of care? The stakes lie in applied policy and practical solutions for custodial services. The second paper explores the experience of caring and being cared for in the context of a prison hospice program, in which incarcerated men provide care to peers who are ill or dying. Through tracing one man’s end of life journey, this chapter considers how hospice caring makes and remakes death and life in prison, and the ways in which this “nefarious” form of escape from disciplinary power translates in the repressive penal regime. The final paper has its roots in sensory ethnography and the emerging field of sensory penality. This is a reflexive piece in which I probe my sensorial subjectivity and particularly touch as a medium of inquiry to explore the sensations of life, death, and dis/connection experienced in a prison infirmary. The observed feel of life and death illuminates new ways of understanding care in custody as a space of simultaneous brutality, beauty, indignity and intimacy. Taken together, the papers shed light on constellations of care in prison, the contingency of relations and personhood, and points of friction between care and custody.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)

abstract: At a time when the prison population is rapidly ageing and more people than ever are dying in custody, this thesis explores what it is like to experience serious or terminal illness in prison, the kinds of care prisoners receive and how they experience that care. Based on ethnographic fieldwork in U.S. state prisons, three themes are examined: 1) how the prison and its privatized health care system shape the illness experiences of older prisoners; 2) how prisoners mediate the experience of dying in prison through a peer- based prison hospice program; and 3) how the senses and especially touch elicit new ways of knowing and understanding end of life in prison. Taken together, the three papers shed light on forms of care in prison, the mutability of relations and life, and points of friction between care and custody.


title: Exploring the Perceptions of Alcohol Use among South Asian (SA) Punjabi Affected Family Members (AFMs) and their Experiences with Problem Drinking

contributor:
LeGris, Jeannette
Nursing

subject: South Asian, Punjabi, Family, Alcohol, Problem Drinking

abstract:
This interpretive description qualitative study explores the perceptions of alcohol use among South Asian (SA) Punjabi affected family members (AFMs) and their experiences with problem drinking from a Canadian community context. It is important to recognize the SA Punjabi community’s perceptions of alcohol use in order to develop a foundational understanding of this phenomenon from a socio-cultural perspective, an area of research that remains poorly understood. This preliminary investigation provides relevant contextual information to deepen our understanding of the experiences of SA Punjabi AFMs. Fourteen SA Punjabi AFMs were interviewed in both English and Punjabi. Analysis of participant narratives
reveals five major themes: normalization of the SA Punjabi drinking culture; socio-cultural gender norms of alcohol consumption; socio-cultural gender related tolerance towards problem drinking; my relative’s drinking is the elephant in the room and I feel helpless and stuck. One of
the themes, my relative’s drinking is the elephant in the room, had three sub-themes: fear of social judgement; fear of causing additional problems and fear of the relative. Interpretation of the participant experiences was facilitated through the use of the Stress-Strain-Coping-Support
model (SSCS) (Orford, Velleman, Natera., et al., 2013). Participant stories highlight the unique socio-cultural experiences of SA Punjabi AFMs impacted by problem drinking. Findings from this study suggest a need for culturally and linguistically appropriate mental health and addictions supports for this community as they navigate the challenges of problem drinking within their families.

abstract: Thesis

abstract: Master of Science (MSc)


title: Development of a Cadmium Zinc Telluride Based Gamma Camera for Simultaneous SPECT/MR Imaging

contributor:
Farncombe, Troy
Biomedical Engineering

abstract:
The current forefront of research in medical imaging technology includes working towards the combination of multiple imaging modalities into a single scan. SPECT is an
imaging modality that would benefit from a combined approach with MRI allowing for
improved diagnostic capabilities particularly in soft tissue regions. However, the traditional detectors used in SPECT are not capable of operating in the presence of an MRI
magnetic field. This has led to the requirement for development of new gamma camera
designs using modern solid state detectors.
We have developed the hardware and software for a gamma camera design using
cadmium zinc telluride detector technology. The camera will be used in a SPECT
system being made up of multiple individual gamma camera modules. These modules
will be placed in a ring that can be inserted into the MRI bore as a stationary insert
for simultaneous SPECT/MR imaging. Testing of the mutual compatibility of the two
systems has led to the development of a gradient triggering hardware and software
protocol. Subsequent testing of this method in a clinical 3T MR was performed. When
gradient triggering was enabled, erroneous event data from the mutual interference was
reduced to near zero levels and resultant images show no structural differences when
compared to control acquisitions. During gradient application, the CZT modules are
suspended, thus yielding a 60% drop in sensitivity due to the additional deadtime of the
triggering. The produced MR image showed a reduction in SNR of 92%. Co-registration
of the MR and gamma camera images was successfully performed, showing both the
physical structural and radioactive activity distribution of the phantom.
Additionally, the potential of a diverging fan beam collimator for use in the multimodal SPECT/MR system was investigated using Monte Carlo simulations. Eleven
collimator designs were compared, yielding between 13 to 23 modules per ring. The results showed that a practical SPECT/MR design using 18 detectors per ring with a 3.83
iii
cm length collimator gave similar tomographic resolution to that of a clinical SPECT/CT
system but with 7.0 times greater detection sensitivity compared to a conventional rotating dual-head camera. The simulations also showed that the system suffers from aliasing
effects when reconstructing features of 7.9 mm or less. To further investigate how the
design choices affected the tomographic resolution, parameters for collimator hole size,
detector pixel size, and number of projection angles were also explored.

abstract: Thesis

abstract: Master of Science in Biomedical Engineering


title: Evaluation of Biomaterial Substitution in Metallurgical Coke

title: THE EVALUATION OF BIOMATERIAL IMPACT ON METALLURGICAL COKE STRUCTURE FOR SUBSTITUTION OF COAL IN OPERATIONAL COAL BLENDS

contributor:
Dogan, Neslihan
Materials Science and Engineering

subject: Biomaterial Coal Blend

abstract: Carbon is a necessary reductant in steel production to convert iron ore to metallic iron. The use of coal and coke causes CO2 emissions to be released into the environment. Using bio-based carbon sources has the potential to offset these emissions and reduce cokemaking overall carbon footprint. The use of biomaterial in coal blends reduces the fossil fuel requirements but to what capacity and type of biocarbon can replace coal is unknown. The full effects of coal and coke characterization from the addition of biomaterial are unknown. In this work, raw biomaterials available to industrial users were evaluated for substitution at low amounts in operational coal blends. Physically, the optical properties of carbon coke forms can provide insight into the strength, reactivity, and performance in the blast furnace, resulting from coal rank and type. The interaction of the biomaterial substitutions with coal during the coking process is evaluated to better understand the reduction in coke strength after reaction (CSR). For this purpose, a series of the pilot oven and sole heated oven tests were performed. When coal was substituted with low amounts of raw biomaterials, the most notable changes in coke texture analysis were to incipient and circular textures. In this work, data from a series of pilot oven and sole heated oven tests showed that fine coke textures and overall inerts increased. The changes in coke textures can be linked to decreases in coke strength after reaction (CSR).

abstract: Thesis

abstract: Master of Applied Science (MASc)

abstract: Metallurgical coke remains the main fuel and reductant source for ironmaking by blast furnace operation. Quality metallurgical coal, a fossil fuel, is required to produce coke. This work continues ongoing steel industry research investigating biomaterial substitution of coal as a more sustainable option. Coal is considered a new release of greenhouse gas (GHG) emissions when used in the steelmaking process compared to a biomaterial which is regarded as a GHG neutral replacement. Three raw biomaterials, available to industrial users, were evaluated for substitution at low amounts and compared to an operational coal blend. The substitution could allow for GHG emissions of the cokemaking processes to be reduced if quality coke can be produced. The interaction of the biomaterial substitutions with coal during the coking process is evaluated in this work to better understand the resultant coke textures related to reduction in coke strength from the substitution.


title: TEXT-BASED TRAFFIC SIGN DETECTION AND TRACKING IN VIDEO

contributor:
Kirubarajan, Thiagalingam
Electrical and Computer Engineering

abstract:
In this thesis, the problem of multiple text-based traffic sign detection and tracking in video is explored, and the following specific problems are addressed: 1) localize the traffic sign in video by fusing the information from the front camera as well as other on-board data source such as rotation of the wheels and directional information of vehicles, 2) a CPU-based text-based traffic sign detector and directional parameter estimation for vehicles based on environmental conditions, 3) a text-based traffic signs detection and tracking framework for real-time application with a low cost data acquisition method.
As a crucial component of Advanced Driver Assistance Systems (ADAS), traffic sign detection and tracking play essential roles in the Automotive Traffic Sign Detection and Recognition (ATSDR) system. Based on their different shapes, colors, letters and symbols, traffic signs in traffic scenario can be roughly categorized to two groups, namely, graphics-based (symbol-based) traffic signs and text-based traffic signs. Graphics-based traffic signs are regulatory signs, warning signs and temporary conditions signs, and text-based traffic signs are information and direction signs. Compared to graphics-based traffic signs, only a few algorithms have focused on text-based traffic signs detection and tracking. Detecting and tracking text-based traffic signs is a challenging task, mainly due to larger variations within the category and limited available dataset.
Starting with localizing text-based traffic sign in urban traffic scenarios, the kinematic states of vehicles and the spatial-temporal relationships between vehicles and traffic signs need to be modelled and estimated. To solve this problem, a kinematic automotive motion model is proposed. This kinematic model fuses information from the front camera as well as other on-board data source such as rotation of the wheels and directional information of vehicles. Based on the proposed kinematic model, a text-based traffic sign localization algorithm is developed. The experiential results on real world video data show that the proposed localization algorithm achieves good performance and significantly reduces the computational cost compared to previously proposed methodologies.
Next, the CPU-based text-based traffic sign detection method is studied. To relax the restriction of directional data acquisition in kinematic automotive motion model, a parameter estimation method is developed based on different environmental/weather conditions. Then, a search region definition approach for traffic signs detection is presented. This approach takes the advantages of spatial-temporal information of the previous frames and different kinematic vehicles motion models in video and largely reduces the massive and repeated detection for common Maximally Stable Extremal Regions (MSERs) detector. From the experiential results, the proposed approach achieves good performance in real-time applications.
Finally, a text-based traffic sign detection and tracking framework is proposed for video-based Traffic Sign Recognition (TSR) system. In the detection stage, a data-driven text-based traffic signs detector is trained with street view images, and a low cost data acquisition approach is presented. In the tracking stage, a multi-traffic signs tracking algorithm is proposed based on kinematic automotive motion model. The framework is evaluated on both public Traffic Guide Panel dataset and our self-collected ETFLab Text-based Traffic Sign Video Dataset. The overall performance demonstrates the effectiveness of the proposed system, which can be better adapted to real-time applications.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Laser Powder Bed Fusion of AISI H13 Tool Steel for Tooling Applications in Automotive Industry

contributor:
Elbestawi, Mohamed
Mechanical Engineering

abstract:
Owing to good combination of high hot hardness, wear resistance, toughness, and fairly low material cost in comparison to its counterparts, AISI H13 tool steel is commonly used in the manufacture of tooling and dies in different industries. Due to the layer-wise nature of the additive manufacturing (AM) techniques such as Laser Powder Bed Fusion (LPBF), they offer substantial geometric design freedom in comparison with conventional subtractive manufacturing methods, thereby enabling construction of complex near-net shape parts with internal cavities like conformal cooling channels.
In the context of AM, processing H13 tool steel is quite challenging, which in turn hurdles its implementation in industrial practices to manufacture reliable tools and dies. Because of the presence of martensite phase (as a brittle phase) and the considerable thermal stresses during the process, H13 tool steel has a high propensity to developing cracks in the final parts. Porosity, and surface quality are other major issues that must be appropriately dealt with. On the other hand, the presence of the residual stresses in the final part begs the question whether the costly stress-relief post-processing is mandatory. After meeting these challenges to get a defect-free parts, it would be of great interest to know if it is possible to utilize the capabilities of AM to design functional materials to enhance wear resistance of the monolithic H13.  The following is the synopsis of the obtained results in regards to the abovementioned discussion.
First, the relative density, surface roughness, crack formation, microstructure, and hardness were evaluated. The relative density is shown to increase with increasing the volumetric energy density and then no significant increase could be pointed out; the maximum relative density of 99.7% was obtained. A preheating of 200°C generally aided to increase the relative density and eliminated the crack formation in the final parts. The microstructure of as-built samples showed a fine cellular-dendritic structure composed of martensite as the predominant phase, and some retained austenite. The microhardness of the as-built samples was found to vary from 650 to 689 HV 0.2, which is superior to a conventionally produced H13 tool steel.
Second, residual stresses, as the other important defect developed during the laser powder bed fusion processing of H13 tool steel was thoroughly examined via experiment and part-level simulations. Twin-cantilever beams and cubic coupons were printed in a wide range of process parameters to characterize the nature of residual stresses and contributing factors under preheated and non-preheated conditions. The residual stresses were assessed using X-ray diffraction method (XRD) as a direct way of getting the residual stress figures at distinct spots and along the depth of cubic coupons. Moreover, the level of beam deflections, as an indication of the magnitude of residual stresses, were both measured and simulated to gain an insight into the accuracy of the part-level simulation. The XRD and beam deflection measurement results revealed the significant role of martensitic phase transformation, process parameters, densification level, and preheating condition on the final residual stress regime and consequently beam deflections. Neglecting the martensitic phase transformation and defects in the deflection modelling introduced a discrepancy between the predictions and experimental measurements. The knowledge gained from the microstructure and residual stress characterizations unraveled that 200°C of preheating eliminates not only the cracks but also the need for stress-relief post-processing.
At last,  the feasibility of fabricating defect-free functionally graded bi-materials (FGMs) with enhanced wear resistance via incorporation of vanadium carbide (VC) into H13 tool steel was investigated. Three distinct composite powders containing 1, 3, and 5wt.%VC were prepared through ball-milling and subjected to laser powder bed fusion (LPBF) process to print different composites on top of monolithic H13 in a wide range of process parameters. Almost fully-dense parts were achieved (maximum of 99.8, 99.8, and 99.5% for 1, 3 and 5wt.%VC composite systems, respectively); however, the increase in VC content narrowed down the processability window range from 60 J/mm3 for 1, and 3wt.%VC systems to 30 J/mm3 for 5wt.%VC system. The mechanical properties of optimum samples were characterized through microhardness, nanohardness, and wear tests. The incorporation of VC significantly improved the mechanical properties, 17-40% in microhardness, 10-40% in nanohardness, and 20-53% in wear resistance. The underlying reasons behind such an improvement were correlated to the dissolution of VC during the heating stage of the LPBF process and the formation of (V+C)-supersaturated solid solution in large extents as a result of extremely high cooling rates. This study introduces LPBF-processed FGMs as promising candidates for applications in which wear resistance is paramount.

abstract: Thesis

abstract: Candidate in Philosophy


title: Leveraging Information Contained in Theory Presentations

contributor:
Carette, Jacques
Farmer, William
Computer Science

subject:
formal methods
algebra library
theorem provers
theory development

abstract:
Building a large library of mathematical knowledge is a complex and labour-intensive
task. By examining current libraries of mathematics, we see that the human effort put
in building them is not entirely directed towards tasks that need human creativity.
Instead, a non-trivial amount of work is spent on providing definitions that could
have been mechanically derived.
In this work, we propose a generative approach to library building, so definitions
that can be automatically derived are computed by meta-programs. We focus our
attention on libraries of algebraic structures, like monoids, groups, and rings. These
structures are highly inter-related and their commonalities have been well-studied
in universal algebra. We use theory presentation combinators to build a library of
algebraic structures. Definitions from universal algebra and programming languages
meta-theory are used to derive library definitions of constructions, like homomorphisms
and term languages, from algebraic theory presentations. The result is an
interpreter that, given 227 theory expressions, builds a library of over 5000 definitions.
This library is, then, exported to Agda and Lean.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)


title: Effects of probiotic on responses to stress: systemic modulation of microbiota-gut-brain axis

contributor:
Forsythe, Paul
Medical Sciences

subject:
stress
microbiota-gut-brain axis
probiotics
immune regulation

abstract: Bacteria, especially symbiotic species in the gastrointestinal tract, have lived with human for long time and are involved in many aspects of host physiology. There is growing evidence that microbiota-gut-brain axis plays an important role in modulating the response to stress in both human and animals. Alterations in the gut microbiota can change the central nervous system function through effects on the endocrine, immune and nervous systems. Recent studies suggest that probiotic treatment may help to maintain resistance against the detrimental effects of stress though the microbiota-gut-brain axis. However, how potentially beneficial bacteria interact with specific immune and neural components, to mediate beneficial effects on behavior remain unclear. Using chronic social defeat stress, a model often used in post-traumatic stress disorder research, we found that administration of Lactobacillus rhamnosus JB-1 beginning 48 hours following chronic social defeat led to persistence of fear memory and social deficits. These effects were associated with changes in gene expression related to emotion and memory in the hippocampus. This was in contrast to previous studies showing that probiotic intervention during social defeat prevents stress induced deficits in social behavior. This indicates that timing of L. rhamnosus treatment in relation to stress exposure has important implications for effects of the bacteria on behavior. In relation to the mechanism of action of L. rhamnosus on behavior, we demonstrate through depletion and adoptive transfer experiments that CD4+CD25+ T cells in mice treated with JB-1 were necessary and sufficient for JB-1 induced anxiolytic and antidepressant-like effects. Evidence also suggested that Ly6Chi monocytes may be a downstream target inhibited by Tregs involved in the behavioral effects of the bacteria. We observed that JB-1 could also reduce the number of activated microglia in the hippocampus, and attenuate hypothalamic-pituitary-adrenal axis reactivity with the integrity of vagus nerve. Crucially we demonstrated that JB-1 induced promotion of peripheral Tregs, reduction in microglia activation in the hippocampus, and attenuation of HPA axis reactivity, were all inhibited following vagotomy indicating that vagus nerve integrity is required to maintain immune and endocrine linkages from gut microbes to the brain. These studies demonstrate prerequisites for beneficial probiotic effects on stress related behaviours including a specific time window in relation to stress exposure, the activation of regulatory immune cells, and undisrupted vagal nerve signalling. These findings highlight the inter-systemic communication of the microbiota-gut-brain axis in the stress response, and might help to unveil more therapeutic opportunities in relation to stress-related mood disorders.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Excessive exposure or dysregulated responses to stress in human and animals induces behavioral changes and the development of mood disorders. The Microbiota-gut-brain axis plays an important role in maintenance of homeostasis. However, crosstalk between the different components of microbiota-gut-brain axis, and how specific microbes can modulate these interactions, remains unclear. Thus, we sought to understand the mechanism of inter-systemic communication linking a specific gut microbe to changes in stress response and behavior. We observed immunoregulation by regulatory T cells were essential in Lactobacillus rhamnosus JB-1 induced anxiolytic and antidepressant-like effects. We also found the integrity of vagus nerve was necessary for JB-1 induced promotion of regulatory T cells and decrease in microglial activation and attenuation of hypothalamic-pituitary-adrenal axis that are associated with the anxiolytic effects of the bacteria. We also identified that the temporal relationship between exposures to stress and the bacteria is important as ingestion of JB-1 directly after chronic social defeat lead to persistence of fear memory and social deficits. This work will help us to understand mechanisms underlying the microbiota-gut-brain axis, which may allow for the development of novel microbe based therapeutic intervention against mood disorders.


title: COMPARATIVE ANALYSIS OF FINNED-TYPE LIQUID-COOLED POWER ELECTRONIC MODULES FOR ELECTRIFIED TRANSPORTATION

contributor:
Emadi, Ali
Mechanical Engineering

subject:
Finned-Type
Liquid-Cooled
Power Electronic Module
Electrified Transportation
Electrified Vehicles
Thermal Management
Heat Transfer
Computational Fluid Dynamics (CFD)
Fin
Comparative Analysis

abstract:
Aggressive demands for high power density and low-cost power modules in the automotive sector pose significant challenges to the thermal management systems.  These challenges necessitate adopting highly effective cooling technologies in power modules to remain competitive in the semiconductor industry. Furthermore, the thermal management strategy must be simple, easy to integrate, compact, effective, efficient, reliable, and economical.

This thesis is an effort to investigate the impact of fin geometry on the overall performance of finned-type liquid-cooled power electronic modules in electrified transportation. The cooling system's performance metrics, including thermal resistance, pressure drop, pumping power, and mass, are discussed in depth. Various cooling technologies are benchmarked. The finned-type cooling technique is chosen over other methods due to simplicity and low pressure drop. Integrated cooling or direct cooling of the module’s baseplate is selected due to considerable thermal resistance reduction because of thermal grease elimination. Potential fabrication techniques are thoroughly explored and compared in terms of mass production and prototyping suitability.

Four different fin shapes, including circular (baseline), drop-shaped, symmetric convex lens, and offset strip in the staggered arrangement, are studied herein. The cooling agent is Water and Ethylene Glycol 50% volumetric mixture (WEG 50%). Typical operating conditions in electrified vehicles (EVs) such as flow rate and inlet temperature are assumed for the numerical analysis. A grid convergence study is carried out to ensure numerical solutions are within an acceptable error band.

The thermal performance evaluation results showed that, on average, offset strip, drop-shaped, and the convex lens performed 39%, 20%, and 6% better than the baseline design, respectively. Additionally, the design candidates are compared in terms of mass and estimated machining cost. The results of the baseline case are verified against empirical correlations from the literature. The maximum deviation is less than 1% and 1.2% for finned-surface temperature and pressure drop, respectively. The difference is attributed to the end-wall effects.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: The impact of Type 1 Diabetes on skeletal muscle fuel substrate storage and ultrastructure in rodents and adult humans

subject: Type 1 Diabetes, Skeletal Muscle, Posttranslational Modifications, Metabolism, Mitochondria, Lipid, Glycogen

abstract:
Type 1 diabetes (T1D) is the result of the autoimmune-mediated destruction of the pancreatic beta-cells leading to the inability to produce insulin sufficiently and, in turn, regulate blood glucose levels. Abnormal levels of blood glucose, specifically hyperglycemia, have been linked to many diabetic complications, with Brownlee proposing decreased GAPDH activity and the resultant increase in four main pathways as the mechanism(s) leading to these complications. Though skeletal muscles play a major role in glucose uptake, they are believed to be relatively protected against these complications as they are able to regulate their glucose uptake. However, evidence is accumulating that skeletal muscles are adversely affected in T1D, particularly with respect to their mitochondrial function. This led us to consider that the skeletal muscles of those with T1D would experience substrate overload (high intracellular lipids and recurrent, high levels of intracellular glucose), which would initiate a negative spiral whereby substrate excess would damage mitochondria - leading to an impaired ability to utilize these substrates - further worsening the substrate overload. Therefore, the objective of this study was to investigate glycogen and intramyocellular lipid (IMCL) content in the muscles of mice and humans with T1D, as well as the potential downstream effects in the form of post-translational modifications (PTMs), mitochondrial content, and lipofuscin accumulation. The Akita T1D mouse model was used to assess substrate overload in uncontrolled diabetes, whereas human participants were used to investigate substrate overload in the presence of insulin therapy. Assessment of glycogen and IMCL content revealed no difference between controls and diabetic cohorts in both the rodent and human study, indicating the lack of substrate overload. Post-translational modifications did not significantly change between Akita and wild-type mice; however, there was a main effect of diabetes on acetylation levels within Akita mice. Lastly, most mitochondrial properties, except for subsarcolemmal pixel density, did not differ either between diabetic and non-diabetic subjects in the human study. Thus, despite mitochondrial complex impairments in diabetic subjects, its extent was not significant enough to cause alterations to the mitochondria as a whole and result in mitochondrial degradation and lipofuscin formation.
This study has provided novel insight into the metabolic properties of skeletal muscle during diabetes. Although there was no indication of substrate overload, diabetes still resulted in some changes to PTM levels and mitochondrial pixel density. However, the effects of these changes did not significantly alter the muscle and resulted in pathway impairments of those that were studied. This could be due to an adaptive mechanism in mice, although future studies are needed to confirm this hypothesis. In the human study, healthy, well-controlled individuals could explain why there was hardly any difference seen, suggesting that controlling glycemic levels was imperative in preventing diabetic complications in muscle.

abstract: Thesis

abstract: Master of Health Sciences (MSc)


title: The search for self-contained numbers: k-special 3-smooth representations and the Collatz conjecture

subject:
Collatz conjecture
self-contained numbers
k-special 3-smooth representations
computational number theory
exponential Diophantine equations

abstract:
The Collatz conjecture is a deceptively simply problem that straddles the line between
number theory and dynamical systems. It asks: if we iterate the function that sends
some even n to n+2 and odd n to 3n+1, will this converge to 1 for every natural number?
This problem has long stood unsolved despite attempts in many mathematical disciplines
– in large part due to the difficulty of predicting the multiplicative structure of a number
under addition. In this project, we provide a derivation of the most standard algebraic
reformulation of the non-trivial cycles subproblem. This results in an infinite family of
exponential Diophantine equations which correspond to k-special 3-smooth representations
of integers. By imposing conditions on the exponents in these representations, we
rewrite it in a multiplicative form that admits iterative solving for parameters of the
representation. Doing so while enforcing a maximum value on the largest power of 2
in the representation, we derive a sufficient condition for no non-trivial cycles existing
in this process. We show that a self-contained number, w, is exactly one which has an
odd element of its orbit modularly equivalent to −3^−1 mod w. We then show that non-cyclicity of any self-contained number greater than 5 is sufficient to show that no cycles
exist in the Collatz process. This differs from previous modularity-based results, and
experimental results suggest that self-contained numbers are relatively rare. We show
that exactly 7 such numbers exist less than 10^15 – improving on the previously known
bound of 10^11.


title: Spatial Patterns of Molecular Traits in Bacterial Genomes

title: Bacterial Molecular Properties and Genomic Position

contributor:
Golding, G Brian
Biology

subject:
Genomic Location
Gene Expression
Origin of Replication
Terminus of Replication
Bacteria
Genomics
Molecular Evolution
Substitutions
Substitution Rate
Genomic Structure
Inversion
RNA-seq
H-NS Protein
Fis Protein
Ancestral Reconstruction

abstract:
The placement of genetic information within bacterial genomes is intentionally organized, creates predictable gradients of molecular properties along the origin-terminus of replication axis. Previous studies have reported that genes located near the origin of replication generally have a higher expression level, increased dosage, and are more conserved than genes located near the terminus of replication. Additionally, substitution rates usually increases with increasing distance from the origin of replication. However, the constant reorganization of genetic information is often overlooked when considering spatial molecular trends.

Here, we explore the interplay of genomic reorganization along the origin and terminus of replication axis of gene expression and substitutions in Escherichia coli, Bacillus subtilis, Streptomyces, and Sinorhizobium meliloti. Using ancestral reconstruction to account for genome reorganization, we demonstrated that the correlation between the number of substitutions and distance from the origin of replication is significant but small and inconsistent in direction. In another study, we looked at the overall expression levels of all genes from the same bacteria, and
confirmed that gene expression tends to decrease when moving away from the origin of replication.

We looked specifically at how inversions - one type of genomic reorganization - impact gene expression between closely related strains of E. coli. Some inversions cause significant differences in gene expression compared to non-inverted regions, however, the variation in expression does not significantly differ between inverted and non-inverted regions. This change in gene expression may be due to the expression regulation properties of two nucleoid proteins, Histone-like Nucleoid-Structuring (H-NS) and Factor for inversion stimulation (Fis), who’s binding sites had a significant positive correlation with inverted regions.

In conclusion, we highlight the impact that genomic rearrangements and location have on molecular trends in bacteria, illustrating the importance of considering spatial trends in molecular evolutionary analysis, and to ensure accurate generalization of previously determined trends. Assuming that molecular trends are exclusively in one direction can be problematic.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)


title: Design, Fabrication, Modeling, and Optimization of Origami-inspired Soft Pneumatic Actuators

contributor:
Bone, Gary M.
Mechanical Engineering

subject: Soft actuators, Origami

abstract: Soft pneumatic actuators produce more energy output per unit mass than conventional rigid pneumatic actuators and are safer for applications involving physical contact with users or fragile objects. The design, modelling, fabrication, and optimization of origami-inspired soft pneumatic actuators (OSPA) are investigated in this thesis. A novel fabrication method employing heat shrinkable polymers conforming to reusable 3D printed molds is proposed. It is rapid, cost-effective, and more systematic than prior OSPA fabrication methods. A nonlinear finite-element analysis (FEA) model for an OSPA based on the accordion crease pattern is developed for predicting the actuator's folding behavior and blocked force. The model includes a nonlinear hyperelastic model of the heat shrink material’s behaviour (obtained empirically) and nonlinear frictional contacts. It is validated with experimental results and is shown to predict the blocked force with a 5.7% maximum error. Prototypes of two OSPA designs (accordion and Yoshimura patterns) are fabricated. Isometric, isobaric, isotonic, and cyclic fatigue tests are performed on the accordion pattern OSPA. The tests demonstrate that it can lift more than 124 times its own weight, and had no decrease in performance after 150,000 contraction/extension cycles with a payload of 2 kg. This durability is superior to existing OSPA. Lastly, a FEA model-based design optimization approach is proposed. A multi-objective genetic algorithm (MOGA) is used to find the origami design parameters that maximize the accordion pattern OSPA's work output. The optimized design is validated experimentally. Although this research focuses on the accordion pattern OSPA, the proposed fabrication, modelling and optimization approaches can be easily adapted to other OSPA designs. In addition to linear force and motion, these actuators can be combined to produce different motions, e.g., a pair of actuators can be connected by a cable to a pulley in an agonist-antagonist arrangement to produce a bidirectional rotary actuator.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Soft pneumatic actuators are lighter than conventional rigid pneumatic actuators and are safer for applications involving physical contact with users or fragile objects. The design, modelling, fabrication, and optimization of origami-inspired soft pneumatic actuators (OSPA) are investigated. A novel fabrication method that is rapid, cost-effective, and more systematic than prior OSPA fabrication methods is proposed. A nonlinear model is developed and shown to predict the OSPA’s output force with a 5.7% maximum error. An extensive series of tests are performed on OSPA prototypes. The accordion pattern OSPA can lift more than 124 times its own weight, and had no decrease in performance after 150,000 contraction/extension cycles with a payload of 2 kg. This durability is superior to existing OSPA. Lastly, a model-based approach for optimizing the OSPA design is presented and validated experimentally. The proposed fabrication, modelling and optimization approaches can be easily adapted to other OSPA designs.


title: Design, Modeling, and Simulation of Directly Frequency- and Intensity-Modulated Semiconductor DFB Lasers

contributor:
Li, Xun
Electrical and Computer Engineering

subject:
semiconductor DFB laser
direct modulation
optical communication
numerical simulation

abstract:
With the rapid development of fiber access networks, data centers, 5th generation cellular networks, and many more, there is an increasing demand for cost effective light sources possessing specification including high frequency modulation efficiency, low noise figure, and high data rate up to 40 Gb/s or even 100 Gb/s. Semiconductor lasers are considered the most attractive candidate in such applications for their low cost, high energy efficiency, and compact size. The focus of this thesis is the development of novel designs of semiconductor DFB lasers for device performance improvement with the help of numerical simulation tools.
The governing equations used in the simulation of DFB lasers are briefly explained, which covers the calculation of optical field, carrier transport, material gain, and thermal diffusion. The TWM based on these governing equations are adopted for the numerical laser solver used in the following chapters for device performance simulation.
Three novel DFB structures are then proposed in the thesis to achieve different specifications. The first proposed structure is a three-electrode DFB laser which can be directly frequency modulated. Numerical simulation shows that a high frequency modulation efficiency of 26GHz/mA from 0 to 100GHz and 17GHz/mA from 100GHZ to 200GHz can be achieved, respectively. Large-signal simulation of the waveform and eye-diagram of a frequency shift-keying (FSK) signal generated by the laser is also performed by converting it to an amplitude shift-keying (ASK) signal through an optical slope filter. The second proposed structure is a DFB laser with asymmetric λ/8 phase-shifted grating designed to flatten the relaxation oscillation peak through longitudinal spatial hole burning (LSHB) effect. Optimization of the phase-shift position to be 25% (in terms of the total length of the cavity) away from the high reflective (HR)-coated facet leads to reduced power leakage thus a higher quality factor of the cavity. The combined effect provides an improved RIN figure for the proposed DFB laser. The third proposed structure is a DFB laser with periodic current blocking grating. This novel grating is designed to improve the modulation bandwidth of DFB lasers by exploiting the enhancement of net differential gain. The effectiveness of the design is verified numerically, and excellent 3dB bandwidth enhancement are found for both uniform grating and λ/4 phase-shifted grating structures.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract:
Semiconductor lasers are by far the most ubiquitous of all lasers, with their applications ranging from communication to manufacturing and from cooling of atoms to sensing of minor movement. And as the fabrication technique of semiconductor laser mature, numerical simulation tools now play the critical role in laser development.
This thesis focuses on the design and simulation of novel structures for distributed-feedback (DFB) lasers to improve the performance of such devices, including the frequency tuning efficiency, relative intensity noise (RIN), and modulation bandwidth. The proposed new structures and the underlying ideas led to them are thoroughly explained in the thesis. The device performances are also investigated numerically by applying traveling wave method (TWM). Simulation results are presented and discussed to provide design guidelines for the proposed structures.


title: ARTIFICIAL MATERIAL 3D PRINTED TEACHING TOOLS FOR CARDIAC SURGICAL SKILLS TRAINING

contributor:
Wohl, Gregory
Mechanical Engineering

subject:
Reverse Engineering
Aortic Valve
CAD Modelling
Simulation Training
Additive Manufacturing
Casting
Mechanical Testing

abstract: PhD Thesis

abstract:
Cardiac surgeons rely on simulation training to improve their surgical skills. The focus of this research was on creating a 3D aortic valve model for cardiac surgical skills training. The research was divided into four different stages including CAD model development, tissue testing using surgical tools, aortic valve model manufacturing and model evaluation.

First, the development of a patient-specific aortic valve model was carried out. The process involved heavily processing CT scanned data of the aortic valve to extract the geometric information via segmentation. Patient-specific models are critical for pre-operative planning and training. However, those models are not ideal for large volume quantities due to the high production costs and the extensive manual labour required to process the models. Therefore, another approach was chosen to produce a generic model that was more suitable for large volume quantities. The generic aortic valve model was developed using data obtained from the literature. The contribution in this stage was developing the methodology to reverse engineer patient-specific cardiac tissues. Additionally, a generic CAD model of the aortic valve was developed.

Second, to select suitable materials for the model, samples from biological tissues and polymers were tested using a surgical tool. The contribution in this stage was documenting the forces and displacements obtained from puncturing and cutting the samples using suturing needles and scalpel blades.

Third, the aortic valve model was manufactured using two approaches including AM and casting. The contribution in this stage revolved around the development of several moulds for casting.

Finally, evaluation of the model was done via an initial assessment session with surgical residents. Although the model was not evaluated in extensive training sessions, a plan highlighting the important elements to do that was included in this research. Thus, the contribution in this stage was developing the model testing plan.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Typically, surgeons use post-mortem human tissues (cadavers) and animal tissues for surgical skills training. However, those methods can be both expensive and limited in availability. Therefore, other non-biological methods are introduced constantly to provide viable alternatives. Those methods include producing models using 3D printing, virtual reality (VR) simulation and even using household items to create training models. However, to date, there is a lack of highly accurate representation of real tissues (fidelity) of most models for cardiac surgical training. The purpose of this research was to develop and manufacture surgical skill training tools for cardiac surgeons focusing on the aortic valve cardiac tissues. The research was divided into several parts including developing computer models using patient-specific medical imaging, developing a general training model and training models manufacturing. Also, the research included manufacturing materials selection process as well as plans for testing the training models in training sessions.


title: Double Hexagon: A Human-Centred Design Framework for Innovation

contributor:
Anand, Christopher
Moll, Sandra
Computing and Software

subject: Human-Centred Design;User Experience;Design Thinking;Co-Design; Experienced-Based Co-Design;Innovation;Healthcare Service Interventions

abstract: Healthcare systems need to adjust services and methods to accommodate the needs, desires, and capabilities of people. Experience-Based Co-Design (EBCD) is the state of the art in participatory service design within the UK National Health Service (NHS), that draws upon design tools and ways of thinking in order to bring healthcare staff and patients together to improve the quality of care. The Co-design process that is integral to the EBCD approach is powerful but also challenging, as it requires active collaboration among multidisciplinary teams, including organizational stakeholders (e.g., investors, managers, advocates, etc.), end-users (e.g., staff, patients, carers, etc.), designers/researchers, and developers. Over the last decade, given the evaluation of the EBCD approach, there has been a gap between theory and practice resulting in limited outcomes in healthcare service improvements. Systematic reviews suggest this low success results from the lack of a systematic elaboration of Co-Design methods, limited tools and insufficient guidance on the ideation process, the tendency to develop a solution without enough divergent thinking, and a poor structure of participation. In order to improve health care services and address the gaps mentioned, we propose a methodology called Double Hexagon, that includes principles of Co-Design, Human-Centred Design, and Design Thinking. This framework is a Human-Centred Design framework that seeks to assist designers and non-designers in moving from designing “product” categories to designing for “people” by providing a concrete and step-by-step realization for “Designing for People”.

abstract: Thesis

abstract: Master of Science (MSc)


title: Bayesian Hierarchical Modelling of Spruce Budworm Development

contributor:
Bolker, Ben
Statistics

abstract: The management of destructive forest pests such as the spruce budworm relies on accurate modelling of their development. Predicting the timing of specific events in the life cycle is crucial for pest control tactics and for modelling the landscape-scale dispersal of the insect. This thesis implements a Bayesian hierarchical thermal response model for the larval stages of the spruce budworm. The model was fitted to data collected from a laboratory rearing experiment on wild spruce budworm colonies collected from locations across Canada and on a fully lab-reared colony. The results were compared across developmental stages and geographic origins. The Bayesian model was implemented with the non-linear, temperature-dependent development rate curve outlined in Schoolfield et al. 1981 and the framework in Régnière et al. 2012 for individual variation and interval censored data. Posterior samples were obtained and a quadratic relationship was observed between developmental stage and an intercept parameter of the development curve. A second model was fitted to the data incorporating this structure. Distributions of development rate estimates at each rearing temperature were obtained from each posterior sample and it was observed that the lab-reared colony developed more quickly than the wild colonies. In future work, the posterior samples can be used to generate simulated populations for prediction, with uncertainty fully propagated throughout.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: Managing forest pests requires an understanding of their life cycle and the ability to predict when life events will occur. It is also important to know whether insects from different parts of the country will develop in the same way. Many models have been created to capture the relationship between temperature and development; this study aims to implement one of these models in a Bayesian framework to get a clearer picture of uncertainty around parameter estimates and predictions. The model was fitted to data from the larval stages of several spruce budworm colonies, each collected from a different location across Canada. These colonies were reared in laboratory conditions, under constant temperature regimes. Estimates of insect development were compared across colonies and across developmental stages.


title: ARGON-OXYGEN DECARBURIZATION OF HIGH MANGANESE STEELS

contributor:
Coley, Kenneth S.
Irons, Gordon A.
Materials Science and Engineering

subject: AOD, Argon-Oxygen Decarburization, High Manganese Steel, Manganese Losses, Evaporation, Evaporation-Condensation

abstract:
Manganese is an essential alloying element in the 2nd and 3rd generation of Advanced High Strength steels (AHSS) containing 5 to 25% manganese. A combination of excellent strength and ductility makes these grades of steel attractive for the automotive industry. To produce these steels to meet metallurgical requirements the main concern for the steelmakers is to decrease the carbon concentration as low as 0.1% while suppressing the excessive manganese losses at high temperatures. Argon Oxygen Decarburization (AOD) is a promising candidate for the refining of high manganese steels.
This work has studied the kinetics of decarburization and manganese losses during the argon oxygen bubbling into a wide range of iron-manganese-carbon alloys. It was shown that decreasing the initial carbon content increased the manganese loss. In the competition between manganese and carbon for oxygen, alloys with lower initial manganese concentrations consumed a higher portion of oxygen for decarburization. This behavior was not expected by thermodynamics and the results did not support the concept of the critical carbon content either. It was demonstrated that for lower range carbon (≤0.42%) alloys, the total manganese loss can be explained by considering multiple mechanisms in parallel; oxide formation (MnO) and vapor formation (Mn (g)), and formation of Manganese mist by evaporation-condensation (Mn (l)). The evaporation-condensation mechanism was proposed with the assumption that the heat generated from MnO and CO formation increases the temperature at the surface of the bubble which facilitates the evaporation of manganese at a high vapor pressure. Consequently, manganese vapor condenses as fine droplets at the lower temperature inside the bubble.
Although dilution of oxygen with argon increased the efficiency of oxygen for decarburization as expected from the mechanism of the AOD process, manganese loss did not stop completely at higher argon concentrations in the gas mixture. Therefore, the bubble and melt do not fully equilibrate with respect to Mn and C.
For high carbon alloys (1%), there was excess oxygen after accounting for CO and MnO formation. According to mass balance and thermodynamic calculations, and assuming manganese loss by evaporation was negligible it was shown that oxygen was distributed amongst MnO, FeO, CO, and CO2.
It was demonstrated that increasing temperature resulted in the higher manganese loss as a mist and by simple evaporation due to the increased vapor pressure and less manganese loss by oxidation. Furthermore, it was found that the rate of decarburization increased with increasing temperature due to more partitioning of oxygen to carbon than manganese.
In addition, it was found that the variations of depth of lance submergence did not affect the rate of decarburization or manganese loss. This means that the reactions occur within such a short time that prolonged time after the reaction is completed does not lead to a repartitioning of the species.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Socioeconomic Inequalities in Suicide and Suicidal Behaviour and Roles of Social Policy

contributor:
Dunn, James R.
Health Policy

subject:
Socioeconomic inequalities in suicide
suicide
social determinants of health
inequity

abstract: There is substantial evidence that suicidal behaviour is disproportionately observed among those with lower socioeconomic positions. Prior literature suggests that policy measures tackling severe socioeconomic deprivation may have impacts on decreasing the health gaps. Yet, little research has been conducted to examine the effects of social and welfare policies on suicidal behaviour and its inequality. This is in part because the understanding of the socioeconomic inequity in suicidal behaviour has been limited by the strong biological individualism, thereby overlooking the potential importance of social and welfare policies to tackle the population-level determinants of suicide. Using jurisdictional and temporal variations in social policies and patterns of suicide, this dissertation contributes to the literature by providing a summary of the current knowledge base of socioeconomic inequality in suicide and suicidal behaviour, identifying the knowledge gaps and future research questions, and adding novel evidence on the impacts of individual social policy and aggregate welfare generosity on suicide mortality and its inequality. In Chapter Two, consists of a scoping review of studies addressing socioeconomic inequalities in suicide and suicidal behaviour or the relationship between socioeconomic positions and different outcomes of suicidal behaviour in high-income countries with quality data. The literature is summarized to map the findings on the socioeconomic inequity in suicidal behaviour. The chapter concludes with an assessment of gaps in the current knowledge base and suggests a future research agenda. In Chapter Three, I examined whether relative welfare generosity in Canadian provinces is associated with overall suicide mortality and employment-based inequalities in suicide mortality by exploiting the provincial differences within Canada. In Chapter Four, I investigated the effects of two recent social pension reforms targeting older adults—Basic Old Age Pension (BOAP) and Basic Pension (BP)—implemented in South Korea on suicide mortality. Taken together, the findings of the dissertation contribute to the existing literature by mapping the relevant literature, identifying research gaps about socioeconomic inequalities in suicide, and suicidal behaviour, and examining the roles of social policy as a moderator of socioeconomic inequalities in suicide.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)

abstract: There is substantial evidence that suicide and suicidal behaviour are disproportionately observed among those with lower socioeconomic positions. Prior literature suggests that policy measures tackling severe socioeconomic deprivation may have impacts on reducing health gaps. However, little research is conducted to examine what effects can be brought by social and welfare policies on suicidal behaviour. This dissertation contains three studies on socioeconomic inequality in suicide and suicidal behaviour and examines the impacts of socioeconomic policies and welfare generosity that may tackle inequality. The overarching aim of the dissertation is to advance our understandings of socioeconomic inequality in suicide and suicidal behaviour by providing a systematic analysis of socioeconomic inequality in suicide and suicidal behaviour and roles of social policy and welfare generosity on suicide and suicide inequality. The dissertation contributes to the literature by mapping the relevant literature, identifying research gaps about socioeconomic inequalities in suicide, and suicidal behaviour and demonstrate novel findings about the roles of social policy.


title: Hydrological and Hydrochemical Dynamics of a Constructed Peatland in the Athabasca Oil Sands Region: Linking Patterns to Trajectory

contributor:
Carey, Sean
Earth and Environmental Sciences

subject: Athabasca oil sands; constructed peatland; hydrology; hydrochemistry

abstract:
Peatlands comprise of approximately half of the Athabasca oil sands region, many of which overlay some of the world’s largest bitumen deposits where surface mining for this resource has permanently altered the landscape. By law, companies must reclaim disturbed landscapes into functioning ecosystems including integrated upland-wetland systems with the objective of forming sustainable peat-forming wetlands. This thesis presents six years (2013 – 2018) of water balance and associated salinity data from one of the two existing constructed upland-wetland systems, the Sandhill Fen Watershed (SFW), a 52-ha upland-wetland built on soft tailings to evaluate the hydrological and hydrochemical performance and its potential to be self-sustaining.
Following a considerable decrease in hydrological management, the dominant water balance components changed from primarily horizontal (inflow and outflow) to vertical fluxes (precipitation and evapotranspiration) which increased inundation, encouraged salt accumulation and changed plant communities. Results suggest that current conditions are not favourable for fen-peatland development as marsh-like conditions have developed, limiting water conserving functions and the ability to persist long-term in a changing climate.
In terms of winter processes, topography currently controls snow accumulation, redistribution and melt at SFW while the role of vegetation in these processes is expected to increase as it continues to develop. Runoff ratios of snowmelt from hillslopes were drastically different than those previously reported for reclaimed peatland watersheds highlighting the influence of different soil materials used during construction. Under various climate change scenarios of a warmer and wetter climate, results from the Cold Regions Hydrological Model indicate that the influence of winter processes will decrease, potentially putting reclaimed systems at greater risk of moisture stress.
Substantial hydrochemical changes have occurred as salinity was relatively low at the study onset as high volumes of inflow and outflow prevented ion accumulation. Over time, salinity continued to increase year-over-year throughout SFW from 2013 to 2018 in the wetland and margin areas. This increase in site-wide salinity was attributed to the shift in dominant water balance fluxes, changes in water table position and increased mixing of SFW waters with deeper saline groundwater that underlies the system. Based on its current conditions, it is unlikely that SFW will support peat-forming vegetation. It is recommended that design strategies shift to incorporate characteristics found in undisturbed saline peatlands that are capable of supporting peat-forming vegetation in a saline environment.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: A better understanding of the hydrological functioning of reconstructed peatlands in the Athabasca oil sands region is required as it is a novel approach in this region and there is potential for thousands of hectares of land that will require this reclamation in the future. Due to their recent establishment potential trajectories of constructed peatlands have yet to be fully analyzed as only recently has sufficient data been collected to evaluate the hydrological and hydrochemical functioning and provide insight on its overall success. While design strategies may seem sound, these constructed systems are completely human-made and it is unclear how they will develop and function in a highly disturbed landscape. Thesis results suggest that current conditions are not favourable to sustain a peatland as marsh-like conditions have developed which will limit its ability to persist long-term in a dry and changing climate. It is recommended that design strategies shift to incorporate characteristics found in undisturbed saline peatlands that are capable of supporting peat-forming vegetation in a saline environment. Due to the many challenges associated with reclamation in this region, lessons learned from this pilot project will help guide future peatland construction.


title: Homeless Jesus: Exploring a Relationship between Public Religious Art and Public Dialogues on Homelessness

contributor:
Gillett, James
Health and Aging

subject:
Public Art
Public Sphere
Religion
Homelessness
Christian Art
Social Change

abstract:
Public art with religious themes or inspiration often represents, promotes, or challenges the concerns, values, characteristics, and/or history of the community in which this art is situated. This dissertation explores the contribution of public religious art to generating dialogue about social issues, in particular homelessness. It builds on scholarship indicating that publicly engaged art is a catalyst for promoting mutual understanding among diverse stakeholders with differing worldviews and joins an ongoing scholarly debate about the place of religion in a secular democratic society. As a case study, I use Timothy Schmalz’s bronze sculpture entitled Homeless Jesus, as an example of public art intended to generate public awareness about social marginalization and homelessness.
Situated within the critical paradigm, this dissertation uses a case study methodology to explore the ways faith-based organizations and secular media elicit and use meanings through the representation of sculpture in public and mediated spaces. To gain multiple vantage points for examining the meanings and uses of Homeless Jesus, this case study draws on interviews with faith leaders at organizations who have a replica or are located near the replica in Hamilton, Ontario (n=12), online news articles that reference it (n=85), and photos of replicas in six urban locations. Data analysis proceeded through three stages: an iconography, a narrative inquiry, and a thematic analysis. This case study culminates in insights on the relationship between public religious art and public dialogues on social issues, such as homelessness. Findings indicate that public religious art is a mode in which faith-based organizations seek to contribute to public dialogues about social issues in a manner that is accessible and acceptable to those with differing worldviews.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)

abstract: Public art with religious themes or inspiration can represent, promote, or challenge the concerns, values, identity, and/or history of the communities in which it is situated. Using Timothy Schmalz’s bronze sculpture entitled Homeless Jesus, as an example of public religious art intended to generate awareness about homelessness, this dissertation explores the contribution of public religious art to public dialogues about social issues. To understand how faith-based organizations and secular media interpret and use Homeless Jesus, I analyze photos of replicas, online news articles that reference it, and interviews with faith leaders at organizations that have a replica or are located near the replica in Hamilton, Ontario. Findings indicate that faith-based organizations use art to contribute to public dialogues in a manner they hope is accessible to and respectful of those with differing worldviews.


title: Efficient Mobile Sensing for Large-Scale Spatial Data Acquisition

contributor:
Zheng, Rong
Computing and Software

subject:
Mobile Sensing
Reinforcement Learning

abstract:
Large-scale spatial data such as  air quality of a city, biomass content in a lake,  Wi-Fi Received Signal Strengths (RSS, also referred as fingerprints) in indoor spaces often play vital roles to applications like indoor localization.  However, it is extremely labor-intensive and time-consuming to collect those data manually.  In this thesis, the main goal is to develop efficient means for large-scale spatial data collection.

Robotic technologies nowadays offer an opportunity on mobile sensing, where data are collected by a  robot traveling in  target areas. However,  since  robots usually have a limited travel budget depending on  battery capacity, one important problem is  to schedule a data collection path to best utilize the budget.  Inspired by existing literature, we consider to collect data along informative paths.  The process to search the most informative path  given a limited budget is known as the  informative path planning (IPP) problem, which  is NP-hard. Thus, we propose two heuristic approaches, namely a greedy algorithm and a genetic algorithm. Experiments on Wi-Fi RSS based localization show that  data collected along informative paths tend to achieve lower errors than  that are opportunistically collected.

In practice, the budget of a mobile robot can vary due to insufficient charging or battery degradation.  Although it is possible to apply the same path planning algorithm repetitively whenever the budget changes,  it is more efficient and desirable  to avoid solving the problem from scratch.  This can be possible since informative paths  for the same area share common characteristics.  Based on this intuition, we propose and design a reinforcement learning based IPP solution, which is able to predict informative paths given any budget. In addition, it is common to have multiple robots to conduct  sensing tasks cooperatively. Therefore, we also investigate the multi-robot IPP problem and present two solutions based on multi-agent reinforcement learning.

Mobile crowdsourcing (MCS) offers another opportunity to lowering the cost of data collection.  In MCS, data are collected  by individual contributors, which is able to accumulate a large amount of data when there are sufficient participants.  As an example, we consider the collection of a specific type of spatial data, namely Wi-Fi RSS, for indoor localization purpose. The process to collect RSS is also known as site survey in the localization community.  Though  MCS based site survey has been suggested  a decade ago~\cite{park2010growing}, so far, there has not been any published large-scale fingerprint MCS campaign. The main issue is that it depends on user's  participation,  and users may be reluctant to make a contribution. To investigate user behavior in a real-world site survey, we design an indoor fingerprint MCS system and organize a data collection campaign in  the McMaster  University campus for five months. Although we focus on Wi-Fi fingerprints,  the design choices and campaign experience are beneficial to the MCS of other types of spatial data as well.

The contribution of this thesis is two-fold. For applications where robots are available for large-scale spatial sensing, efficient path planning solutions are investigated so as to maximize data utility. Meanwhile, for MCS based data acquisition, our real-world campaign experience and user behavior study reveal essential design factors that need to be considered and aspects for further improvements.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: A variety of applications such as environmental monitoring require to collect large-scale spatial data like air quality, temperature and humidity. However, it usually incurs dramatic costs like time to obtain those data, which is impeding the deployment of those applications. To reduce the data collection efforts,  we consider two mobile sensing schemes, i.e, mobile robotic sensing and mobile crowdsourcing. For the former scheme, we investigate how to plan paths for mobile robots given limited travel budgets. For the latter scheme, we design a crowdsourcing platform and study user behavior through a real word data collection campaign. The proposed solutions in this thesis  can benefit large-scale spatial data collection tasks.


title: Investigating the Role of RNA-Binding Motif Protein 17 (RBM17) in Acute Myeloid Leukemia Stem Cells

contributor:
Lu, Yu
Biochemistry and Biomedical Sciences

subject: LSC

subject: RBM17

abstract:
AML is thought to be sustained by sub-populations of LSCs, which possess the capacity for self-renewal and differentiation and are believed to be responsible for disease initiation, relapse and chemo-resistance. Previous studies demonstrated that aberrant splicing is prevalent in AML patients, in particular within the LSC populations. Dysregulated AS pathway members may represent key therapeutic targets and diagnostic markers for facilitating AML treatments. Here, we demonstrated the splicing factor RBM17 is significantly higher expressed in LSCs and is associated with AML poor prognosis. Gene expression signature of AML patients with higher RBM17 expression is similar to LSC gene signature. Importantly, knockdown of RBM17 in primitive primary AML cells results in myeloid differentiation and the impairment of their stem and progenitor potential. By performing global analysis of the RBM17-RNA interactome and proteome changes downstream of RBM17 knockdown, we show that RBM17 knockdown leads to inclusion of poison exons and production of nonsense-mediated decay (NMD)-sensitive transcripts for pro-leukemic factors such as RBM39 and EZH2, along with the translation initiation factor EIF4A2. We further show that EIF4A2 expression is enriched in LSC populations and inhibition of EIF4A2 impairs colony-forming ability of primary AML. Proteome analysis of AML cells after EIF4A2 knockdown demonstrate that knockdown of EIF4A2 largely recapitulates the biological effect of RBM17 knockdown. These two proteins also share downstream proteins enriched in ribosome biogenesis pathways. By applying a modified dCas9/sgRNA assisted chromatin-protein complex purification method, we identify CDK12 and USP16 as two potential upstream regulators of RBM17 and demonstrate that RBM17 mRNA expression is repressed by CDK12 knockdown but promoted by USP16 knockdown.
Altogether, these results provide a rationale to target RBM17 and/or its downstream NMD-sensitive splicing substrates and upstream regulators in primitive leukemic cells for AML treatment.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Acute myeloid leukemia (AML) is a cancer of blood and bone marrow, accounts for 30% of all leukemia and is associated with low overall survival rate and high relapse frequency due to AML chemo-resistance. It is believed that relapse and resistance are in part due to the persistence of leukemic stem cells (LSCs). Aberrant alternative splicing (AS) is a common characteristic of AML and LSC, involved splicing factors may represent useful therapeutic targets. Through data-mining survey for 203 splicing factors, comparing their expressions in LSC-enriched and non-LSC subsets of AML patients and correlations with AML prognosis, we identified RNA-binding motif protein 17 (RBM17) as the only one of these splicing factors that is strongly linked to poor prognosis in AML and has higher expression in LSC-enriched AML samples. RBM17 has been observed in high levels in several solid tumors and was able to confer cancer cells to chemo-resistance, yet the mechanism and its role in AML LSC remain to be determined. By manipulating RBM17 in AML samples, we observed how RBM17 affect the disease progression. Further, through applying omics technologies, we identified RNA binding sites, splicing substrates, downstream protein targets, and upstream regulators of RBM17 in AML, establishing the critical role of RBM17 in regulating AS program in LSC to support disease maintenance. Overall, this work provides potential strategies to target RBM17-related core pathways for AML treatment.


title: Novel Treatment Technologies for Nutrients Recovery and Biosolids Management

contributor:
Kim, Younggy
Civil Engineering

subject:
Nutrients Recovery
Biosolids Management

abstract:
High energy consumption in conventional wastewater treatment contributes to a large amount of greenhouse emissions and causes environmental problems such as acid rain and climate change. Many technologies, microbial electrolysis cells (MECs), electrodialysis (ED), and anaerobic digestion (AD), were developed to make wastewater treatment more efficient and economical. This thesis investigated novel MECs and ED to decrease energy consumption in wastewater treatment and recover resources from wastewater. In addition, inhibition of ammonia and acetic acid on high-solid AD was examined in this research.
 The multi-electrode stack design was applied in MECs to treat municipal wastewater. Rapid organic removal and minimized biosolids production were observed in the stacked MECs. In addition to municipal wastewater treatment, MECs can also recover/remove heavy metals from industrial wastewater. Various removal/recovery mechanisms of toxic heavy metals were discussed in this thesis. ED with bipolar membranes (BPMs) was examined to produce high-purity ammonium sulfate from real wastewater steams. This examination indicates valuable nutrients resources (e.g., ammonium sulfate) can be recovered from wastewater and used as land fertilizers for food production. Membrane scaling problems were also evaluated in ED systems since the formation of inorganic scalants can affect the efficiency of nutrients recovery significantly. In addition, the inhibition of ammonia and acetic acid on AD performance was incorporated in a modified anaerobic digestion model (ADM) for reliable simulation of individual biological reactions in high-solid AD.
This research contributes to the body of knowledge by developing wastewater treatment technologies with less energy consumption and biosolids production. The reduction of energy consumption and biosolids production can reduce fossil fuel combustion and waste disposal. Resources, such as ammonia and heavy metals, can be recovered and reused by using the investigatory technologies. Therefore, with these developed technologies, wastewater treatment meets the goal of sustainable development and helps to establish a new green circular economy.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: High energy consumption is a main challenge in wastewater treatment. However, a large amount of energy in wastewater can be recovered and reused. The recovery of energy from wastewater can reduce energy costs, save resources, and protect the environment. This research aims to develop novel wastewater treatment technologies to save energy by recovering nutrients and producing biogas from wastewater. Bioelectrochemical systems are used to produce hydrogen gas and recover heavy metals from municipal or industrial wastewater. Electrodialysis systems are applied in ammonia recovery and fertilizer production. Anaerobic digestion systems are employed to produce methane gas as a renewable energy source from wasted sludge. These technologies reduce energy consumption in wastewater treatment and help to establish a new green circular economy for resource recovery.


title: Poly-N-isopropylacrylamide-based Thermoresponsive Hydrogels for Retinal Pigment Epithelial Cell Delivery

contributor:
Sheardown, Heather
Chemical Engineering

subject:
Age-Related Macular Degeneration
cell delivery
thermoresponsive hydrogel
pNIPAAm
biomaterials
tissue regeneration

abstract:
Despite being the most prevalent presentation of Age-Related Macular Degeneration (AMD), dry AMD (dAMD) lacks a therapeutic treatment. Retinal pigment epithelium (RPE) dysfunction preceding the onset of dAMD has inspired interest in regenerative medicine approaches seeking to replenish the RPE and preserve visual acuity. Cell delivery to the subretinal space however has been met with challenges surrounding ease of access and invasive surgical implantation. Two-dimensional scaffolds have made use of natural and polymeric materials to act as carriers for RPE cells and various progenitor lines. These substrates mitigate issues surrounding the handling of delicate cell sheets harvested for transplant. As well, they are often successful in preserving RPE phenotype, supporting growth, and can be fine tuned to possess morphologies comparable to native extracellular matrix (ECM). Despite aiming to act as replacement Bruch’s membrane on which RPE resides, two-dimensional substrates are often notably bulky and require traumatic surgery for implantation.
As a result, the use of injectable methods of cell delivery has gained appeal. Bolus injections, despite improved methods of administration, are correlated with issues of inadequate cell localization. In response, three-dimensional hydrogel carriers for retinal applications aim to encapsulate cells, allowing for better cell distribution as these materials spread throughout the subretinal space. Increased viscosity of hydrogels as compared to saline injections, is hypothesized to improve cell loss and reduce aggregation. Of particular interest are in situ gelling systems, which undergo physical changes upon injection. Gelation upon delivery works to further assist in maintaining the cells within their target site.
Purity and reproducibility concerns associated with the use of natural materials in the development of hydrogel cell carriers, have inspired the use of synthetic thermoresponsive poly-N-isopropylacrylamide (pNIPAAm). pNIPAAm undergoes a liquid to gel transition at a lower critical solution temperature (LCST) of 32°C. Copolymerization with various hydrophobic and hydrophilic groups can be used to adjust gel properties such as increasing or decreasing LCST, allowing for degradation, and improving water retention.
In the work described herein, two NIPAAm-based thermoresponsive hydrogels intended for use as subretinal cell carriers are proposed.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Atrial Fibrillation Occurring Transiently with Stress

contributor:
Whitlock, Richard Paul
Health Research Methodology

subject:
atrial fibrillation
non-cardiac surgery
noncardiac surgery
medical illness
AFOTS

abstract:
ABSTRACT
Atrial fibrillation (AF) is frequently detected in the setting of an acute physiologic stressor, such as medical illness or surgery. It is uncertain if AF detected in these settings (AFOTS: AF occurring transiently with stress) is secondary to a reversible trigger or is simply paroxysmal AF. This distinction is critical for clinicians and patients, as they must decide if AFOTS can be dismissed as a reversible phenomenon, or if it justifies the need for chronic therapy; in particular, anticoagulation to reduce the risk of disabling stroke. The uncertainty in the management of AFOTS is exacerbated by a poor understanding of its epidemiology. How frequently does AFOTS occur? Are there higher risk groups? What is the natural history of this condition? Across 8 chapters, this thesis systematically assesses previously published literature on this topic, focusing on patients who have an acute medical illness or have undergone noncardiac surgery, and addresses knowledge gaps therein.
Chapter 1 is an introduction that outlines the justification of each of the studies in the thesis.
Chapter 2 is a narrative review that defines AFOTS conceptually and outlines research priorities.
Chapter 3 is a systematic review that explores the incidence and recurrence of AFOTS associated with acute medical illness.
Chapter 4 is a systematic review and meta-analysis that explores the incidence and recurrence of AFOTS associated with acute noncardiac surgery.
iii
Chapter 5 examines the profiles of pacemaker-detected “subclinical” AF occurring before and after a hospitalization for medical illness or noncardiac surgery
Chapter 6 reports the design, rationale and final results of a prospective study that aimed to provide a precise and accurate estimate of the incidence of AFOTS in critically ill patients.
Chapter 7 reports the design and rationale of a matched prospective cohort study designed to estimate the rate of recurrence of AF following hospitalization with AFOTS and to compare it to similar patients who did not have AFOTS.
Finally, Chapter 8 outlines the conclusions, discusses the limitations, and presents the implications of the research in this PhD thesis.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Atrial fibrillation (AF) is the most common abnormal heart rhythm. AF is often diagnosed when a patient is hospitalized for an illness or after surgery. When AF is first found in this setting, it is unclear whether it has the same prognosis as other forms of the disease or is reversible. This thesis examines this problem and designs and executes studies to address it.


title: Disparities in Tenure and Promotion Outcomes Among Racialized and Female Faculty in Canadian Universities

contributor:
Robson, Karen
Sociology

abstract: Universities are often seen as inclusive and liberal spaces where equity and social justice prevail. Despite this ideal image, racial and gender disparities continue to persist and have been documented. Racialized faculty are less likely to be university professors (Ramos, 2012) and have lower earnings (Li, 2012). Similarly, female professors are less likely to be promoted (Nakhaie, 2007; Stewart, Ornstein & Drakich, 2009) and experience significant wage gaps compared to their male colleagues (Momani, Dreher & Williams, 2019). Drawing on original survey data from the University, Tenure, Promotion and Hiring (UTPH) survey, this dissertation examines inequities in promotion for racialized and female Canadian faculty at different stages of their career (e.g., tenure, promotion to associate professor, promotion to full professor). It also looks at commonly-cited explanations such as human capital theory, cultural or identity taxation, and glass ceiling theory to see if they can be used to adequately explain the disparities in promotion that exist. Finally, this dissertation examines perceptions of the factors that influence tenure, promotion, and hiring to examine whether racialized faculty see the academy differently from their non-racialized counterparts. When examining the chapters in this dissertation collectively, it is clear that there are systemic inequalities that exist within universities that affect the career trajectories of racialized and female faculty in Canada. This dissertation concludes with a critical examination of various institutional responses in recent times and future directions for research.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)


title: Examining the Pheromonal Potential of Estradiol in the Big Brown Bat

title: Estradiol as a Potential Pheromone in Bats

contributor:
Faure, Paul A.
Psychology

subject:
Estradiol
Pheromone
Chiroptera
Urinary Steroids
Reproduction
Endocrinology
Big Brown Bat
Eptesicus fuscus

abstract: Historically, physiologists have believed steroid hormones act exclusively within the individual producing them. However, studies in mice have shown that bioactive 17β-estradiol (E2) is excreted in male urine and absorbed by female conspecifics where it binds to estrogen receptors in reproductive other tissues. This can lead to pregnancy disruption and/or cause precocious puberty in female conspecifics. In bats the transfer of tritium-labelled estradiol (3H-E2) from male to females has been shown during the mating season. I investigated the influence of season on 3H-E2 transfer and showed that females housed with 3H-E2 injected males had significantly higher levels of radioactivity in reproductive, neural, and peripheral tissues during reproductively relevant timepoints compared to the non-reproductive season. Because urine has been hypothesized as the vector of steroid hormone transmission in mice, I examined the natural patterns of sex steroids in the urine of male and female big brown bats (Eptesicus fuscus) across the annual reproductive cycle. I found that creatinine-adjusted E2, which corrects for animal hydration and activity, was significantly higher in male than female urine, and in adult compared to yearling urine. Seasonal differences in urinary E2 levels were observed within and between sexes. Finally, I designed a protocol to investigate the attractant properties of body odour and urine between bat sexes during the mating season. Using a two-alternative Y-maze arena, I found that female bats first approach the test arm containing urine of a male conspecific before exploring the arm with female urine. Females also tended to spend more time in the test-arm containing male urine and being in the male test-arm at the conclusion of the 5 min trial. My data supports the hypothesis that E2 has the potential to act as reproductive pheromone with urine as a likely vector. Given the close proximity of individual bats within a maternity roost, steroid hormone transfer between conspecifics quite likely occurs in nature and could have profound influences on female reproductive behaviour (e.g. receptivity) and physiology (e.g. estrus cycling). My research provides new evidence for the potential pheromonal actions of E2 in bats that is consistent with how sex steroids act as pheromones in other mammals.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)

abstract: Historically, physiologists have believed steroid hormones act exclusively within the individual producing them. However, studies in mice have shown that bioactive 17β-estradiol (E2) is excreted in male urine and absorbed by female conspecifics where it binds to estrogen receptors in reproductive and other tissues. This exogenous E2 can result in changes to female reproductive physiology and behaviour. Our lab has previously observed E2 to transfer between male and female captive big brown bats during the mating season. Research from this thesis provides evidence that the transfer of E2 from male to female bats is highest during times of mating and ovulation/fertilization. I also demonstrate that E2 naturally occurs in the urine of both male and females with age, sex, and seasonal differences in concentration. Lastly, I show that female bats are attracted to the urine of males. My research provides new evidence for the potential pheromonal actions of E2 in bats that is consistent with how sex steroids act as pheromones in other mammals.


title: Investigating And Extending The Quanta Tracking Algorithm

contributor:
Kirubarajan, Thia
Electrical and Computer Engineering

subject: tracking Quanta track-before-detect TBD HPMHT Quanta

abstract:
The traditional tracking approach of forming detections and then associating these detections together is known to perform poorly at low signal-to-noise ratios (SNR). Track-before-detect (TBD) approaches, where the sensor data is used directly as opposed to forming detections, has been shown to perform better than traditional approaches at low SNRs.

One recently introduced TBD algorithm is the Quanta Tracking Algorithm that is formed by applying maximum likelihood estimation to the histogram probabilistic multi-target tracker (HPMHT). Quanta has shown promising performance for low SNR scenarios, but the body of literature is small and the evaluations that have been done so far do not consider several practical aspects of using the algorithm in real applications and are difficult to compare to
other algorithms due to the SNR definitions used. This paper seeks to address these deficiencies in the literature. A re-derivation of Quanta that corrects some issues present in the original derivation while also integrating extensions from the HPMHT literature will also be presented. These extensions are shown to make Quanta able to correct for errors in the assumed size targets as well as improve estimating the SNR of fluctuating targets.

abstract: Thesis

abstract: Master of Applied Science (MASc)