title: Inertia- and elasticity-driven turbulence in viscoelastic fluids with high levels of drag reduction

contributor:
Xi, Li
Chemical Engineering

subject:
Turbulent Flows
Vortex Dynamics
Viscoelasticity
Drag Reduction

abstract:
In dilute polymer solution, polymers are able to change the flow structures and suppress the intensity of turbulence, resulting in a considerable friction drag reduction (DR). Despite the extraordinary progress made in the past few decades, some critical questions remain unanswered. This dissertation will try to address two fundamental questions in dilute polymeric turbulence: (I) interactions between polymers and turbulent motions during the qualitative low-extent to high-extent drag reduction (LDR and HDR) transition in inertia-driven turbulence, (II) roles of the inertia- and elasticity-driven turbulent motions in the dynamics of high elasticity polymeric flows.

Many studies in the area of DR turbulence have been focused on the onset of DR and the maximum drag rection (MDR) asymptote. Between these two distinct stages, polymeric turbulent flows can also be classified into the qualitative LDR and HDR stages. Understanding the polymer-turbulence interactions during the drastic LDR-HDR transition is of vital importance for the development of efficient flow control technology. However, knowledge regarding this qualitative transition is still limited. In our DNS (direct numerical simulation) study, differences between the LDR and HDR stages are presented by a number of sharp changes in flow structures and statistics. Drag reduction in the flows is thus governed by two different mechanisms. The first is introduced at the onset of DR, which has been well explained by the indiscriminate suppression of turbulent fluctuations during the coil-stretch transition of polymers. The second mechanism starts at the LDR-HDR transition but its physical origin is not clear. Based on instantaneous observations and indirect statistical evidence, we proposed that polymers, after the LDR-HDR transition, could suppress the lift-up process of the near-wall vortices and modify the turbulent regeneration cycles. However, direct evidence to support this hypothesis is not available without a statistical analysis of the vortex configurations. Therefore, a new vortex tracking algorithm -- VATIP (vortex axis tracking by iterative propagation) -- is developed to analyze statistically the configurations and distribution of vortices. Implementing this method in the polymeric turbulence demonstrates that the lift-up process of streamwise vortices in the buffer layer is restrained at HDR, while the generation of hairpins and other three-dimensional vortices is suppressed. In addition, the characteristic lifting angle of conditional eddies extracted by a conditional sampling method is found to be larger in HDR than in the Newtonian turbulence. These observations all support our hypothesis about the mechanism of LDR-HDR transition.

Research on the low elasticity turbulence usually considered the flow motions to be Newtonian-like. Turbulence here is driven by the inertial force (and hence called ``inertia-driven'' turbulence (IDT)) while polymers are responsible for dissipating turbulent kinetic energy. In the high elasticity turbulence, recent studies found a completely different turbulent flow type in which turbulence is driven by the elastic force and polymers could also feed energy to the flow. The behaviors of this ``elasticity-driven'' turbulence (EDT) are of significant interest in this area because of its potential connection to the MDR asymptote. However, EDT is difficult to capture by the traditional pseudo-spectral DNS scheme (SM) as a global artificial diffusion (GAD) term is involved in the polymer constitutive equation to stabilize the simulation. In our study, a new hybrid pseudo-spectral/finite-difference scheme is developed to simulate the polymeric turbulence without requiring a GAD. All of the spatial derivative terms are still discretized by the Fourier-Chebyshev-Fourier pseudo-spectral projection except for the convection term in the constitutive equation which is discretized using a conservative second-order upwind TVD (total variation diminishing) finite difference scheme. The numerical study using the hybrid scheme suggests that turbulent flows can be either driven by the inertial or the elastic forces and respectively result in the IDT and EDT flows. A dynamical flow state is also found in the high elasticity flow regime in which IDT and EDT can be sustained alternatively.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Turbulence is known to consume kinetic energy in a fluid system. To enhance the efficiency of fluid transportation, various techniques are developed. Especially, it was found that a small amount of polymers in turbulent flows can significantly suppress turbulent activity and cause considerable friction drag reduction (DR). Extraordinary progress has been made to study this phenomenon, however, some questions still remain elusive. This dissertation tries to address some fundamental questions that relate to the two typical polymeric turbulent motions: the inertia- (IDT) and elasticity-driven turbulence (EDT). In IDT, mechanisms of transitions between the intermediate stages are investigated from the perspective of vortex dynamics. The different effects of polymers at each stage of the flow lead to different flow behaviors. Particularly, starting from the low- to high-extent DR transition, the lift-up process of vortices is suppressed by polymers. The regeneration cycles of turbulence are thus modified, which results in qualitative changes of flow statistics. Numerical study on EDT is enabled by a newly developed hybrid pseudo-spectral/finite-difference scheme. A systematic investigation of the parameter space indicates that EDT is one self-contain turbulence driven purely by the elastic force. It can also interact with IDT and lead to a dynamical flow state in which EDT and IDT can alternatively occur.


title: THE CONTROLS AND DRIVERS OF DISSOLVED ORGANIC CARBON QUANTITY AND DISSOLVED ORGANIC MATTER QUALITY IN AN IMPACTED GREAT LAKES WATERSHED

contributor:
Carey, Sean
Geography and Earth Sciences

subject:
dissolved organic carbon
hydrology
dissolved organic matter
Spencer Creek Watershed

abstract: Intensely managed and modified catchments in the Great Lakes are linked to eutrophication and hypoxia of receiving water bodies downstream, resulting in water quality impairment, and adverse impacts on aquatic ecology. While much focus has been on the role of phosphorous and nitrogen, dissolved organic carbon (DOC) plays a complex and critical role in lake biogeochemical cycles, as it influences the interations between nutrients and contaminants in water and soil through processes of mobilization, transport, biological uptake, and deposition. Human-dominated landscapes have a range of consequences on DOC dynamics as catchment hydrology, plant cover, and nutrient inputs are altered in these environments. As such, the objectives of this study were to identify the controls and drivers of DOC quantity and DOM quality in the Spencer Creek watershed, which is the largest contributor of water to Cootes Paradise that ultimately drains into Lake Ontario. The 159 km2 study area of the catchment is complex, as the present landscape is composed of a mosaic of various land uses including agriculture, forest, wetland, urban, and industrial regions. Flow alterations contribute to the complexity of the watershed as there are managed reservoirs and alterations in water courses. From 2016- 2018, hydrometric data was collected across 9 monitoring sites, along with surface water samples that were analyzed for DOC concentration and optical properties. Results indicate differences in flow magnitudes and stream DOC between dry and wet conditions, where concentrations during wet conditions were significantly higher compared to dry. Additionally, there was substantial variation in DOC concentration and quality across the Spencer Creek watershed. DOC concentrations were found to be the lowest at groundwater influenced sites in the headwaters of the watershed, and the highest in the mid-catchment region where DOC quality was strongly influenced by wetland sources. The reservoir-influenced sites showed relatively intermediate concentrations of DOC, with quality that exhibited strong microbial signatures. At the outlet, DOC concentrations were attenuated and DOC quality was intermediate between allochthonous and autochthonous end members, reflecting upstream mixing processes. These processes were presented as a conceptual model of water and DOC movement through the Spencer Creek watershed. The implications of this research suggest that with anticipated wetter and warmer conditions DOC concentrations would increase in the watershed. The repercussions of increased DOC concentrations overall imply a decrease of terrestrial carbon storage, and greater input into more reactive and susceptible pools, which may result in further water quality degradation. Overall, the findings from this research provide insight into the fate and transport of water and DOC in a complex, managed catchment in the Great Lakes region, with the aims of providing key information for local stakeholders.

abstract: Thesis

abstract: Master of Science (MSc)


title: ASEMS: Autonomous Specific Energy Management Strategy

contributor:
Emadi, Ali
Mechanical Engineering

subject:
Autonomous Vehicle
Hybrid Electric Vehicle
Autonomous Driving
Energy Management Strategy
Self-driving car
Optimization
Convex Optimization
Electrification
Sustainability
Optimal Control
Model Predictive Control
Receding Horizon
Fuel Economy
Path Planning
Trajectory Planning
Powertrain

abstract:
This thesis addresses the problem of energy management of a hybrid electric power unit for an autonomous vehicle. We introduce, evaluate, and discuss the idea of autonomous-specific energy management strategy. This method is an optimization-based strategy which improves the powertrain fuel economy by exploiting motion planning data.
First, to build a firm base for further evaluations, we will develop a high-fidelity system-level model for our case study using MATLAB/Simulink. This model mostly concerns about energy-related aspects of the powertrain and the vehicle. We will derive and implement the equations for each of the model subsystems. We derive model parameters using available data in the literature or online. Evaluation of the developed model shows acceptable conformity with the actual dynamometer data. We will use this model to replace the built-in rule-based logic with the proposed strategy and assess the performance.\par
Second, since we are considering an optimization-based approach, we will develop a novel convex representation of the vehicle and powertrain model. This translates to reformulating the model equations using convex functions. Consequently, we will express the fuel-efficient energy management problem as the convex optimization problem. We will solve the optimization problem using dedicated numerical solvers. Extracting the control inputs using this approach and applying them on the high-fidelity model provides similar results to dynamic programming in terms of fuel consumption but in substantially less amount of time. This will act as a pivot for the subsequent real-time analysis.\par
Third, we will perform a proof-of-concept for the autonomous-specific energy management strategy. We implement an optimization-based path and trajectory planning for a vehicle in the simplified driving scenario of a racing track. Accordingly, we use motion planning data to obtain the energy management strategy by solving an optimization problem. We will let the vehicle to travel around the circuit with the ability to perceive and plan up to an observable horizon using the receding horizon approach. Developed approach for energy management strategy shows a substantial reduction in the fuel consumption of the high-fidelity model, compared to the rule-based controller.

abstract: Thesis

abstract: Master of Science in Mechanical Engineering (MSME)

abstract: The automotive industry is on the verge of groundbreaking transformations as a result of electrification and autonomous driving. Electrified autonomous car of the future is sustainable, energy-efficient, more convenient, and safer. In addition to the advantages of electrification and autonomous driving individually, the intersection and interaction of these mainstreams provide new opportunities for further improvements on the vehicles. Autonomous cars generate an unprecedented amount of real-time data due to excessive use of perception sensors and processing units. This thesis considers the case of an autonomous hybrid electric vehicle and presents the novel idea of autonomous-specific energy management strategy. Specifically, this thesis is a proof-of-concept, a trial to exploit the motion planning data for a self-driving car to improve the fuel economy of the hybrid electric power unit by adopting a more efficient energy management strategy. With the ever-increasing number of autonomous hybrid electric vehicles, particularly in the self-driving fleets, the presented method shows an extremely promising potential to reduce the fuel consumption of these vehicles.


title: Development of Chimpanzee Adenovirus-Vectored Vaccine Strategies Against Pulmonary Tuberculosis

contributor: Medical Sciences (Molecular Virology and Immunology Program)

subject:
Tuberculosis
Mucosal immunity
Mucosal vaccination
Chimapnzee adenovirus
Vaccine
Therapeutic

abstract:
The immense global tuberculosis (TB) burden highlights the shortcomings of current vaccination and antibiotic regimens. Novel prophylactic TB vaccines that can either boost or replace BCG entirely remains an active area of research. Additionally, the success of current antibiotic therapies against TB is hindered by their complexity and duration, with large percentages of patients failing to complete treatment.
Multi-armed approaches are required to properly and efficiently combat diseases. Besides prophylactic vaccines, development of therapeutic vaccine strategies as an adjunct to antibiotic treatment would represent another major step in TB control. To achieve such a goal, vaccines must consider the pathogen’s life cycle, the immunological responses which they drive, and the populations in which they will ultimately be administered.
As such, the purpose of this dissertation is to utilize state-of-the-art molecular cloning techniques to construct novel chimpanzee adenovirus-vectored vaccines that provide prophylactic and therapeutic immunity against pulmonary TB. By considering different phases of the pathogen’s life cycle, we aim to select a collection of antigens that are protective, regardless of disease state. Development of such platforms would lay and bolster the groundwork for improved vaccine strategies against TB.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)


title: Real World Secret Leaking

title: REAL WORLD SECRET LEAKING: THE DESIGN AND ANALYSIS OF A PROTOCOL CREATED FOR THE PURPOSE OF LEAKING DOCUMENTS UNDER SURVEILLANCE

contributor:
Samavi, Reza
Stebila, Douglas
Computing and Software

subject:
Security
Cryptography
Secret Leaking
Whistleblowing

abstract:
In scenarios where an individual wishes to leak confidential information to an unauthorized party, he may do so in a public or an anonymous way. When acting publicly a leaker exposes his identity, whereas acting anonymously a leaker can introduce doubts about the information’s authenticity. Current solutions assume anonymity from everyone except a trusted third party or rely on the leaker possessing prior cryptographic keys, both of which are inadequate assumptions in real-world secret leaking scenarios.
In this research we present a system called the attested drop protocol which provides confidentiality for the leaker, while still allowing leaked documents to have their origins verified. The protocol relies on identities associated with common communication mediums, and seeks to avoid having the leaker carry out sophisticated cryptographic operations. We also present two constructions of the general protocol, where each is designed to protect against different forms of adversarial surveillance. We use ceremony analysis and other techniques from the provable security paradigm to formally describe and evaluate security goals for both constructions.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: Whistleblowing is an activity where an individual leaks some secrets about an organization to an unauthorized entity, often for moral or regulatory reasons. When doing so, the whistleblower is faced with the choice of acting publicly, and risking retribution or acting anonymously and risking not being believed. We have designed a protocol called the attested drop protocol, which protects the identity of the whistleblower, while allowing the unauthorized entity to have a means of verifying that the leak came from the organization. This protocol makes use of preexisting identities associated with a communication medium, such as emails, to avoid using cryptographic primitives that are impractical.


title: Factors Influencing Microbiota Diversity and Composition During Early Postnatal Development

contributor:
Foster, Jane
Neuroscience

subject:
Gut Microbiota
Neurodevelopment
Gene-Environment
Stress
Gut-Brain Axis

abstract: The human gut and brain have a bidirectional communication that has shown to play a pivotal role in our health and disease. Literature has shown that microbiota composition and diversity can be influenced by both genetic and environmental factors, contributing to shaping an individual’s microbial composition. The current work includes analysis of the microbiome of several mouse models to better understand how gene-environmental interactions during early development can influence the composition of microbiota within the gut. Here, male and female mice from several strains (C57BL/6, Balb/C, FVB, CD1) and genetically modified mice including T-cell receptor knock out mice (TCRβ-/-δ-/-) and Fragile-X-mice (FMR1-KO) were exposed to early life stressors including lipopolysaccharide (LPS) injection on postnatal day 3 (P3) and/or overnight maternal separation on P9. Fecal samples were collected at P24 and microbiota composition was determined by amplifying the 16s rRNA gene variable 3(v3) region and sequenced using the MiSeq Illumina platform. DADA2, was used to analyze this data in R software. Among the group, strain was found to be significant among alpha and beta diversity metrics while sex and stress were found to contribute to within strain variation, which demonstrated that both genetic and environmental factors are important in shaping an individual’s microbial composition. Secondly, we also explored the role of gut microbiota on the development of the immune system in TCRβ-/-δ-/- and C57BL/6 mice. Mice that lack T-lymphocytes were found to have a lower alpha diversity, as well as separated from their wild-type controls by beta diversity. Several bacterial taxa were found to be influenced by the immune system, demonstrating a bidirectional communication between the gut and T-cells.  Lastly, the influence of litter, an environmental factor on microbial composition was explored within inbred mouse strains, C57BL/6 and Balb/C. Litter was found to influence alpha diversity, in which litters among C57BL/6 exhibited the greatest variation in such diversity. Beta diversity was also found to be influenced by litter, as related litters were found to cluster together. Differences in bacterial taxa between the inbred strains were observed and a subset of those taxa were found to be influenced by litter. Hierarchical clustering and co-occurrence analysis revealed different clusters of co-occurring taxa between both strains. These findings demonstrate that environmental factors can contribute to influence the composition of microbiota.

abstract: Thesis

abstract: Master of Science (MSc)


title: STACKING DEFECTS IN GaP NANOWIRES: OPTICAL AND ELECTRONIC EFFECTS AND ADSORPTION OF CATECHOL GROUP ONTO METAL OXIDE SURFACE

contributor:
Rubel, Oleg
Materials Science and Engineering

subject:
Nanowire
Optoelectronics
Density functional theory
Catechol
Supercapacitor
photoluminisence
GaP
adsorption
Mn3O4
stacking faults
twin
defect

abstract:
The research performed aims to develop a deeper understanding and prediction of behaviour of complex chemical and physical systems using density functional theory
(DFT) modelling complemented by experimental techniques. We focus on phenomena
relevant to practical applications of semiconducting materials.
Semiconductor nanowires, produced by the vapor-liquid-solid method are being considered for applications in photo sensors, field effect transistors, light emitting diodes
(LEDs) and energy harvesting devices. In particular, semiconductor nanowire based
photovoltaic devices show potential for lower cost due to less material utilization and
greater energy conversion efficiency arising from enhanced photovoltage or photocurrent due to hot carrier or multiexciton phenomena enhanced light absorption, compared
to conventional thin film devices. Further, freedom from lattice matching requirements
due to strain accommodation at the nanowire surfaces enable compatibility with a wide
variety of substrates including Silicon. Thus understanding and improving the optoelectronic properties of nanowires is of great interest. In the first paper, we study the
effect of planar defects on optoelectronic properties of nanowire based semiconductor
devices. Specifically, we were interested in investing the origin of various features observed in the photoluminisence (PL) spectrum of GaP nanowire using density functional
modelling, which are not well understood.
In the second paper, we work to model bonding characteristics during a chemical
synthesis. We focus on the synthesis of nanoparticles for supercapacitor application. In
the past decade, comprehensive research has been emphasized on manganese oxides for electrochemical supercapacitor (ECS) applications. Mn3O4 has gained significant interest due to its compatibility with capping agents and the unique spinel structure allows
for potential modifications with other cations. Many metal oxide synthesis techniques
are based on aqueous processing. The synthesized particles are usually dried and redispersed in organic solvents to incorporate water-insoluble additives such as binders to
fabricate films and devices. However, during the drying step nano-structures are highly
susceptible to agglomeration, which can be attributed to the condensation reactions occurring between particles and reduction in surface energy. Poor electrolyte access due
to agglomeration and low intrinsic conductivity of Mn3O4 are detrimental to the performance of Mn
3O4 electrode especially at high active mass loadings. Numerous attempts
have focused on controlling size and morphology of Mn3O4 nanostructures using capping agents, which have strong adhesion to particles surface to inhibit agglomeration.
Catechol containing molecules have been used for dispersion of metallic nanoparticles
and fabrication of composite thin films, resulted in narrow size distribution of nanoparticles and strong adhesion to substrates. Despite the experimental results showing good
adsorption of catechol group to metal atoms, the mechanism is unclear since it is highly
influenced by synthesis parameters. We use Infrared spectroscopy in conjugation with
density functional modelling to understand the binding mechanism of 3,4 dihydroxy
benzaldehyde onto Mn3O4 surface.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: How do systems achieve their goals? The role of implementation in mental health systems improvement

title: Implementation in mental health systems

contributor:
Lavis, John N
Health Policy

subject:
implementation
mental health
policy

abstract: Effectively addressing mental health and substance use problems are important challenges faced globally. People experiencing such problems encounter many societal barriers that can affect their ability to participate as full members of society and have life expectancies much shorter than the general population. Policies to address mental health and substance use problems require the mobilization of multiple sectors, such as health, education, and justice. While there is strong evidence for programs and services that work, and there are policy directions aimed at achieving better service experiences and improved health and social outcomes, there is a lack of knowledge about how to get these policies and programs embedded effectively into daily practice – a process called implementation. The objective of this dissertation is to advance the understanding of implementation strategies for addressing such complex challenges through five original scientific contributions. The first is a critical interpretive synthesis of existing literature to generate a theoretical framework of the implementation process from the perspective of a policy goal by integrating findings from the public policy, implementation science and knowledge translation fields. Next is a two-part comparative case study exploring how policy implementation was structured and the strategies used in large, well-developed mental health systems. Last is a two-part in-depth examination of mental health policy implementation efforts in Ontario, Canada, beginning with an analysis of the development and implementation of the province’s mental health strategy, followed by an examination of the role that citizens and other stakeholder groups played in its implementation. Together these studies contribute theoretical, substantive and methodological insights toward understanding the effective implementation of policy directions for complex social challenges. Better implementation means more citizens can benefit from effective policies and programs that are needed across populations.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: People with mental health and substance use problems face many barriers that can affect their ability to participate in society. In order to make a positive impact on mental health, changes need to be made in a number of different areas such as health, education and justice. There is now research evidence about programs and policies that are effective, but there is a lack of understanding of how to get those changes into policy and practice so that people can benefit from them – a process called implementation. This thesis answers questions about implementation in mental health systems to help fill this gap. It contributes: 1) a new theory of implementation from the perspective of a policy goal; 2) insights about the infrastructure needed to support large-scale implementation; and 3) an understanding of how citizens and other stakeholders contribute to implementation by examining Ontario’s mental health and addictions strategy.


title: Compact Low-Cost Ultra-Wideband Pulsed-Radar System

contributor:
Nikolova, Natalia K.
Electrical and Computer Engineering

subject:
Radar
Ultra Wideband Radar
Field Programmable Gate Array
Microwave Circuits
Microwave Sensors
Sampling Methods

abstract: Recently, the advent of the integrated circuits (ICs), the monolithic microwave integrated circuits (MMICs) and the multiprocessing computer technology have provided numerous opportunities to make the radar technology compact and affordable.  The ultra-wideband (UWB) technology gives many advantages over the traditional narrowband radar systems due to its high spatial resolution, low susceptibility to interference, superior penetration depths, and increased peak power.  However, the ability to digitize and reconstruct the full UWB signal spectrum comes at a considerable cost and size.  Ultimately, high-speed sampling rates above 10 giga-samples per second (GSPS) are beyond the abilities of conventional analog-to-digital converters (ADCs).  The UWB technology is inaccessible to the end-user for various advanced applications in microwave imaging and detection.  The purpose of this work is to provide a low-cost, dual-channel UWB pulsed-radar system that is readily available with a 1:10 system bandwidth.  The advancements in low-cost alternatives for compact and portable designs empower many promising UWB applications.  Here, the desired bandwidth is from 500 MHz to 5 GHz, which utilizes a fast pulse repetition frequency (PRF) in short-range applications.  The preliminary results from the novel Equivalent-Time Sampling Receiver are promising with an equivalent-time sampling rate up to 20 GSPS.  Nevertheless, the system design is versatile for bandwidth tuning in order to meet the needs of different applications.  This versatility is enabled by: i) selection of the effective sampling rate through the field-programmable gate array (FPGA) programming environment, ii) choice of the receivers' front-end track and hold (T & H) amplifier bandwidth, iii) a collection of different PRFs from the low kilohertz up to 20 MHz, iv) tuning of the pulse generator bandwidth, and v) simultaneous multi-channel capabilities enabling antenna beam-forming, polarization diversity and spatial diversity. The result is a fully functional prototype that costs a fraction of traditional bench-top solutions.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Investigating Neuropsychological Functioning, Functional Impairment, and Cognitive Remediation in Posttraumatic Stress Disorder

contributor:
McKinnon, Margaret C.
Psychology

subject:
PTSD
Neuropsychological Function
Functional Impairment
Cognitive Remediation

abstract:
Posttraumatic stress disorder (PTSD) is associated with significant functional
impairments and disruptions in cognitive functioning. Functional recovery and remediation of cognitive difficulties are oft over-looked treatment targets in this population, despite their significant contribution to the burden of PTSD to the individual and to society. Existing literature suggests that functional impairment and cognitive dysfunction may not respond to first-line treatments for PTSD. Thus, the focus of this thesis was to examine symptom dimensions associated with cognitive dysfunction and functional impairment among individuals with PTSD, and to investigate a novel approach to cognitive remediation, Goal Management Training (GMT), in this population. Study one in this thesis is a review in which we identified a strong relation between dissociative symptoms and neuropsychological functioning, transdiagnostically and among individuals with PTSD. The hypothesis that dissociative symptoms would be strongly related to functional impairment among individuals with PTSD was explored in study two. We found that dissociative symptoms mediated the relation between PTSD symptoms and functional impairment among a sample of military members, veterans, and first responders with PTSD. Study three identified that emotion regulation difficulties and dissociative symptoms most strongly predicted functional impairment among civilians with PTSD and high rates of exposure to childhood abuse and neglect. In study four we investigated the effectiveness of a cognitive training program, Goal Management Training (GMT), in improving cognitive functioning, clinical symptoms, and functional impairment among inpatients with PTSD. Participation in GMT was associated with improved cognitive functioning and increased ability to engage in goal directed behaviours when highly emotional. This thesis highlights the importance of assessing emotion regulation difficulties and dissociative symptoms in order to target functional impairment and cognitive dysfunction among individuals with PTSD. Moreover, it provides evidence for a potential treatment approach to ameliorate these difficulties.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract:
Posttraumatic stress disorder (PTSD) is a mental health condition that develops after exposure to a traumatic event. It is associated with reduced functioning in important areas of life, including social relationships, work performance, and self-care. PTSD is also associated with reduced cognitive functioning in areas such as memory, planning, and organization. This thesis focuses on examining variables that may be related to these difficulties, including specific symptoms such as difficulty managing emotions and
difficulties remaining in the present moment (dissociation). We also investigate a treatment program, Goal Management Training (GMT), aimed at teaching skills to improve cognitive and daily functioning. By understanding what contributes to cognitive functioning and functional difficulties in individuals with PTSD and by providing evidence for a treatment that can improve these difficulties, we hope to improve the lives of individuals with PTSD.


title: Clinical Diagnosis of Carpal Tunnel Syndrome

title: CLINICAL DIAGNOSIS OF CARPAL TUNNEL SYNDROME: A SYSTEMATIC REVIEW AND COGNITIVE INTERVIEWING STUDY OF A DIAGNOSTIC QUESTIONNAIRE

contributor:
MacDermid, Joy C.
Rehabilitation Science

subject:
Carpal tunnel syndrome
Systematic review
Diagnosis
Cognitive interviewing

abstract:
Background: Carpal Tunnel Syndrome (CTS) is a condition affecting wrists and hands, causing pain, tingling, and numbness. Despite the high prevalence of CTS and the existence of several diagnostic tools, there is no consensus over a diagnostic gold standard test.
Thesis Objectives: To conduct a systematic review of diagnostic test accuracy of clinical scales, questionnaires and hand symptom diagrams/maps for the diagnosis of CTS in people suspected with this condition; and to do a cognitive interviewing qualitative study of the Kamath and Stothard questionnaire, a diagnostic tool for CTS, to identify and resolve potential sources of error.
Methods: In the first study, we searched MEDLINE, CINAHL, and Embase databases keywords related to diagnostic accuracy and clinical tests of CTS. In the second study, we interviewed clinicians and people diagnosed with CTS and other upper extremity conditions. We recorded, and content analyzed their opinion on comprehensiveness and comprehensibility of Kamath and Stothard questionnaire.
Results: Twenty-one articles met the eligibility criteria of the systematic review, of which nine were on the diagnostic accuracy of hand symptom diagrams and twelve assessed the diagnostic accuracy of clinical scales and questionnaires for the diagnosis of CTS. Positive likelihood ratios (LRs) to diagnose or rule in CTS ranged from 0.94 for Boston carpal tunnel questionnaire to 10.5 for CTS-6 scale, and negative LRs to rule out CTS ranged from 1.05 to 0.05 for the same diagnostic tools. In the cognitive interviewing study, we categorized the areas of uncertainty in the participants’ responses into five themes: clarity and comprehension (51%), relativeness (38%), inadequate response definition (3.75%), perspective modifiers (3.75%), and a reference point (2.5%).
Conclusions: Very few high-quality studies exist on the diagnostic accuracy of CTS-6, Kamath and Stothard questionnaire, Bland questionnaire, and Katz and Stirrat’s hand symptom diagram. By doing cognitive interviews, we identified options for potential improvement in the wording of the Kamath and Stothard questionnaire. Future studies should assess the diagnostic properties of the proposed modified questionnaire, and high-quality studies are warranted to assist in deciding on ruling in or out CTS.

abstract: Thesis

abstract: Master of Science (MSc)

abstract:
Carpal tunnel syndrome is a condition affecting the hands, causing feelings of burning pain, pins and needles, heaviness and/or lack of sensation. This condition is very common among people who do manual work and can make them unable to do their jobs and daily living tasks. Early diagnosis of carpal tunnel syndrome is very important in starting an appropriate plan of treatment. The best diagnostic test for carpal tunnel syndrome is still uncertain.
In the first study, we collected studies of the questionnaires and hand maps that exist for the diagnosis of carpal tunnel syndrome. We then tried to summarize the information that assists clinicians in making a diagnostic decision. In the second study, we interviewed people about their opinion of a questionnaire that is used in hand clinics to diagnose carpal tunnel syndrome.
We concluded that more studies with high quality are needed to confidently decide which diagnostic test is best. Also, we revised a questionnaire that is currently used, and we hope that these revisions make the questionnaire more relecant and understandable for people.


title: Convolutional Neural Network Detection and Classification System Using an Infrared Camera and Image Detection Uncertainty Estimation

contributor:
Habibi, Saeid
Mechanical Engineering

subject:
Autonomous Driving
Thermal Imaging
Infrared
Neural Network
Uncertainty Estimation
Tracking
Image Detection
Image Classification

abstract:
Autonomous vehicles are equipped with systems that can detect and track the objects in a vehicle’s vicinity and make appropriate driving decisions accordingly. Infrared (IR) cameras are not typically employed on these systems, but the new information that can be supplied by IR cameras can help improve the probability of detecting all objects in a vehicle’s surroundings. The purpose of this research is to investigate how IR imaging can be leveraged to improve existing autonomous driving detection systems. This research serves as a proof-of-concept demonstration.
In order to achieve detection using thermal images, raw data from seven different driving scenarios was captured and labelled using a calibrated camera. Calibrating the camera made it possible to estimate the distance to objects within the image frame. The labelled images (ground truth data) were then used to train several YOLOv2 neural networks to detect similar objects in other image frames. Deeper YOLOv2 networks trained on larger amounts of data were shown to perform better on both precision and recall metrics.
A novel method of estimating pixel error in detected object locations has also been proposed which can be applied to any detection algorithm that has corresponding ground truth data. The pixel errors were shown to be normally distributed with unique spreads about different ranges of y-pixels. Low correlations were seen in detection errors in the x-pixel direction. This methodology can be used to create a gate estimation for the detected pixel location of an object.
Detection using IR imaging has been shown to have promising results for applications where typical autonomous sensors can have difficulties. The work done in this thesis has shown that the additional information supplied by IR cameras has potential to improve existing autonomous sensory systems.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Defining Age-Appropriate BMI Cut-Points for Older Adults

contributor:
Raina, Parminder
Health Research Methodology

subject:
Aging
Body Mass Index

abstract:
OBJECTIVES: In older age, body composition changes as fat mass increases and redistributes. Due to this, the current body mass index (BMI) classification proposed by the World Health Organization (WHO) may not accurately classify older adults (65+) by health risk. The objectives of thesis were to: 1) conduct a scoping review of the literature to investigate the association between BMI and mortality in older adults, 2) define age-specific BMI cut-offs for older adults with regards to health outcomes using data from the Canadian Longitudinal Study on Aging (CLSA), and 3) test the performance of the age-specific BMI thresholds in comparison to WHO thresholds.
METHODS: The Ovid MEDLINE and EMBASE databases were searched for English language observational studies examining the association between BMI and all-cause mortality in older adults (objective 1). CART decision tree analysis was then used to define age-appropriate BMI cut-points in relation to health outcomes (i.e. cardiovascular (CV) conditions and frailty) (objective 2). Logistic regression models were utilized to determine the association between BMI and health outcomes, and area under the receiver operating characteristic curve (AUC) and sensitivity/specificity were used to test the performance of new BMI cut-offs (objective 3).
RESULTS: The scoping review found that older adults classified as overweight had reduced mortality compared to normal BMI, thereby necessitating a need for revised cut-offs. In our analyses, age-specific cardiovascular- and frailty-BMI groups were created. Compared to the BMIFrailty- Risk groups, the BMI-CV-Risk groups demonstrated the most improvement in classification from the WHO groups. When evaluating the association between cut-points and outcomes, the model performance and specificity both improved for the new age-specific cut-points compared to the original WHO thresholds, suggesting improved classification with use of these revised groups. The results propose increased overweight thresholds (25.9-27.1) and lowered obese thresholds (28.7-30.9) for older adults.
CONCLUSIONS: This novel analysis is the first attempt at revising the WHO-BMI thresholds for older Canadian adults. The age-specific BMI-CV-Risk groups offered improvements in classification of older adults from the WHO-BMI groups, and these findings suggest that a higher overweight but lowered obese thresholds may be best suited to older adults. Further work must be done to validate these thresholds in other populations and ethnicities, as well as in the context of other health outcomes.

abstract: Thesis

abstract: Master of Science (MSc)


title: Comparing Protocell and Surface-Based Models of RNA Replicator Systems and Determining Favourable Conditions for Linkage of Functional Strands

title: Simulations of RNA Replicator Systems

contributor:
Higgs, Paul
Physics and Astronomy

subject:
Origin of Life
RNA World
Protocells
Surface
Computational Models
RNA Polymerase

abstract: In hypothesized RNA-World scenarios, replication of RNA strands is catalyzed by error-prone polymerase ribozymes. Incorrect replication leads to the creation of non-functional, parasitic strands which can invade systems of replicators and lead to their death. Studies have shown two solutions to this problem: spatial clustering of polymerases in models featuring elements to limit diffusion, and group selection in models featuring protocells. Making a quantitative comparison of the methods using results from the literature has proven difficult due to differences in model design. Here we develop computational models of replication of a system of polymerases, polymerase complements and parasites in both spatial models and protocell models with near identical dynamics to make meaningful comparison viable. We compare the models in terms of the maximum mutation rate survivable by the system (the error threshold) as well as the minimum replication rate constant required. We find that protocell models are capable of sustaining much higher maximum mutation rates, and survive under much lower minimum replication rates than equivalent surface models. We then consider cases where parasites are favoured in replication, and show that the advantage of protocell models is increased. Given that a system of RNA strands undergoing catalytic replication by a polymerase is fairly survivable in protocell models, we attempt to determine whether isolated strands can develop into genomes. We extend our protocell model to include additional functional strands varying in length (and thus replication rate) and allow for the linkage of strands to form proto-chromosomes. We determine that linkage is possible over a broad range of lengths, and is stable when considering the joining of short functional strands to the polymerase (and the same for the complementary sequences). Moreover, linkage of short functional strands to the polymerase assures more cells remain viable post division by ensuing a good quantity of polymerase equivalents are present in the parent cell prior to splitting.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: Collections of RNA polymers are good candidates for the origin of life. RNA is able to store genetic information and act as polymerase ribozymes allowing RNA to replicate RNA. Polymerases have been experimentally developed in labs, however none are sufficiently general to work well in an origins of life setting. These polymerases are vulnerable to mistakes during copying, making survival of RNA systems difficult. Such systems have been studied by computer simulations, showing that the strands need to be kept together for survival, either on surfaces or in primitive cells. Differences in the details of the models has made comparing the surfaces to cells difficult. This work creates a unified model base allowing for comparison of these two environments. We find that the existence of primitive cells is very beneficial to systems of RNA polymers and thus it is likely such cells existed at the origin of life.


title: Constellation Design for Multi-user Communications with Deep Learning

contributor:
Zhang, Jian-Kang
Electrical and Computer Engineering

subject:
Autoencoder
Deep Learning
MIMO

abstract:
In the simple form, a communication system includes a transmitter and a receiver. In the transmitter, it transforms the one-hot vector message to produce a transmitted signal. In general, the transmitter demands restrictions on the transmitted signal. The channel is defined by the conditional probability distribution function. On receiving of the transmitted signal with noise, the receiver appears to apply the transformation to generate the estimate of one hot vector message. We can regard this simplest communication system as a specific case of autoencoder from a deep learning perspective. In our case, autoencoder used to learn the representations of the one-hot vector which are robust to the noise channel and can be recovered at the receiver with the smallest probability of error.
Our task is to make some improvements on the autoencoder systems. We propose different schemes depending on the different cases. We propose a method based on optimization of softmax and introduce the L1/2 regularization in MSE loss function for SISO case and MIMO case, separately. The simulation shows that both our optimized softmax function method and L1/2 regularization loss function have a better performance than the original neural network framework.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Becoming Ideal Canadians: The Cultural Adjustment and Citizenship Trials of British War Brides

contributor:
Frager, Ruth
History

subject: British War Brides; Canada; gender; women; Second World War; immigration; housing crisis; citizenship; Canadian nationalism; Ontario; Quebec; Britain;

abstract: Historical work on British war brides has been limited to the creation and collection of nostalgic interview anthologies; often by the women themselves or their children. These anthologies focus on the meeting of Canadian servicemen and British women and the women’s journey to and reunion with their husbands in Canada. Discussions of life in Canada and negative experiences are only briefly mentioned. This dissertation argues that this nostalgic view of war brides in the historical literature hides the immigration, settlement, and citizenship challenges faced by these women in Canada during and after the Second World War. Reception of war brides by the Canadian government and public was not as positive as the current scholarship has suggested. While some war brides flourished in Canada, others experienced adaptational problems, including differences in language and religion, navigating Canada’s housing crisis, and hostile in-laws. A few women also experienced problems related to abandonment, abuse, or husbands with undiagnosed post traumatic stress disorder. Since divorce was difficult to get at the time, these women tended to suffer in silence. Some war brides and their children even experienced problems with their citizenship, due to sexist provisions in the Canadian Citizenship Act in 1946, and changes to the Act in 1976, which made proof of citizenship necessary for all Canadians; something that many war brides were unaware of. This dissertation examines the creation and evolution of Canadian citizenship from a perspective that highlights its initial racism and sexism, as well as the consistent bureaucratic bungling regarding the application of its provisions since 1947. While these cases were fixed by amendments to the Citizenship Act in 2008 and 2014 by the Harper government, the citizenship conundrums that this community faced raise interesting questions about what citizenship means and who gets to be a Canadian citizen.

abstract: Thesis

abstract: Candidate in Philosophy

abstract:
Most historical work about British war brides has been overly nostalgic and focussed on the collection and creation of interview anthologies; often created by these women and their children. Discussions of life in Canada and negative experiences are only briefly mentioned.
This dissertation argues that this nostalgic view of war brides in the historical literature hides the immigration, settlement, and citizenship challenges faced by these women in Canada during and after the Second World War. The different experiences of these women reveal biases towards their background and gender, relationships damaged by the trauma of war, bureaucratic incompetence in the immigration and citizenship process, and raises important questions about national belonging and the nature of Canadian citizenship, from the post-war period to the present.


title: TARGETED AND NON-TARGETED METABOLITE ANALYSIS FOR DISEASE RISK ASSESSMENT: MEASURING BIOMARKERS OF SMOKE EXPOSURE AND HABITUAL DIET

contributor:
Britz-McKibbin, Philip
Chemistry

subject: metabolomics, exposomics, Western diet, prudent diet, boronic acid, sialic acid, firefighter, diet, urine, plasma, serum, mass spectrometry, capillary electrophoresis, CE-MS, biomarker, chemometrics, UV-Vis, fluorescence, polyaromatic hydrocarbons, gas chromatography, GC-MS, wood smoke

abstract:
Exposomics applies metabolomics methods and technologies to the comprehensive
analysis of all low molecular weight molecules (< 1.5 kDa) in complex biological
samples to characterize the interaction between cellular metabolism and exogenous
lifestyle exposures that determine health and quality of life. To fully access the
diverse classes of biological molecules related to an individual’s metabolic profile,
metabolomics frequently requires the use of complementary analytical platforms,
and employs targeted and untargeted molecular profiling strategies to identify
biomarkers that are clinically relevant to an individual’s health status. Chapter 2
describes a quinoline-based boronic acid biosensor for N-acetylneuraminic acid that
undergoes a striking binding enhancement under strongly acidic conditions. For the
first time, this work allows for direct analysis of acidic sugars with high selectivity
when using UV absorbance or fluorescence detection based on formation of a
highly stable boronate ester complex with metabolites containing an α-hydroxycarboxylate moiety. Chapter 3 describes a targeted analysis of 24 different
organic contaminants using GC-MS that can serve as biomarkers of recent smoke
exposure following search-and-rescue training exercises by firefighters located at
three different sites across the province of Ontario. Importantly, skin and possible
respiratory uptake of various polycyclic aromatic hydrocarbons, methoxyphenols,
and resin acids was confirmed by peak excretion of several wood smoke biomarkers
in urine within 6 h following acute exposure. Chapter 4 applied a cross-platform
metabolomics strategy based on CE-MS and GC-MS in order to identify and
validate dietary biomarkers in matching plasma and urine samples collected from
healthy participants in the pilot Diet and Gene Interaction Study (DIGEST). For the
first time, we demonstrate that a panel of metabolites can serve as reliable
biomarkers following contrasting Prudent and Western diets over 2 weeks of food
provisions, which correlated well with self-reported diet records. This work paves the way for the development of objective biomarkers for accurate assessment of
wood smoke exposures, as well as complex dietary patterns as required for new
advances in occupational health and nutritional epidemiology.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)

abstract:
Exposomics is an emerging multidisciplinary science aimed at deciphering the
complex interactions that impact human health and gene expression, such as
lifestyle choices (i.e., habitual diet) and lifelong environmental exposures. There is
growing interest in identifying biomarkers that can be readily measured for chronic
disease prevention given an alarming global prevalence of obesity and
cardiometabolic disorders, including heart disease, type 2 diabetes and cancer. The
research in this thesis focuses on developing new analytical methods for identifying
and quantifying metabolites that may allow for better assessments of human health,
and has contributed to the development of novel biosensors for the targeted analysis
of N-acetylneuraminic (sialic) acid and related acidic sugars, as well as high
resolution methods for broad spectrum analysis of biotransformed organic
contaminants from smoke exposure by GC-MS, and plasma and urinary metabolites
that differentiate contrasting Prudent and Western diets and correlate well with self-reported
diet records.


title: Potential Factors Influencing the Acute and Chronic Response of Human Skeletal Muscle to Interval Exercise Training

contributor:
Gibala, Martin
Kinesiology

subject:
exercise
skeletal muscle
interval training
mitochondria
physiology

abstract: This thesis considered three potential factors that may influence skeletal muscle responses to interval exercise training in healthy adults, with a focus on mitochondrial remodelling: biological sex, fibre type and contraction pattern. Study 1 assessed the acute response to a sprint interval training (SIT) protocol that involved three, 20-second ‘all-out’ cycling efforts interspersed with 2 minutes of recovery. It found similar exercise-induced increases in the mRNA expression of genes linked to mitochondrial biogenesis in men and women. Study 2 showed that a single session of SIT and moderate-intensity continuous training (MICT) induced similar increases in the phosphorylation of signalling proteins linked to mitochondrial biogenesis in type I and IIa fibres when compared within the same individuals. It also assessed responses to 12 weeks of training in two different groups and found MICT elicited greater increases in markers of mitochondrial content, including cytochrome c oxidase subunit IV (COXIV) protein content, in type I fibres, whereas the increase in type IIa fibres was similar compared to SIT. Study 3 utilized single-leg cycling as a within-subject model to compare interval and continuous training protocols that were matched for exercise intensity and total training volume, but the pattern of contraction differed. Measurements of mitochondrial content, including subsarcolemmal mitochondrial area, the maximal activity of citrate synthase and COXIV protein content, increased after 4 weeks of continuous training but were unchanged after interval training.  Overall, this thesis advances our understanding of the influence of biological sex, muscle fibre type and contraction pattern on skeletal muscle mitochondrial responses to exercise. Major findings include: the acute response to SIT was similar between sexes, acute responses to interval and continuous exercise were similar but training elicited some divergent fibre type-specific responses, and mitochondrial content increased following continuous training but was unchanged following work- and intensity-matched interval training.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)

abstract: This thesis considered the role of biological sex, fibre type and contraction pattern on skeletal muscle responses to exercise. It focused on mitochondria, which are important components of the cell that affect health and performance. The responses of genes that regulate the formation of new mitochondria to a single session of brief, “sprint” interval exercise were similar between men and women. Acute sprint interval exercise also activated molecular pathways similar to traditional endurance exercise in the two main types of muscle fibres; however, 12 weeks of endurance training induced greater increases in mitochondrial content in type I (“slow-twitch”) fibres, whereas the increases in type II (“fast-twitch”) fibres were similar compared to interval training. Lastly, mitochondrial content increased after continuous training but not interval training when the intensity and total amount of exercise was matched. Our findings improve our understanding of the mechanisms by which exercise elicits mitochondrial remodelling in humans.


title: Radio-over-Free-Space Optical Fronthauling for Cloud Radio Access Networks

contributor:
Hranilovic, Steve
Electrical and Computer Engineering

subject:
Free-space optical communications
Cloud radio access network
optical communications
optical fiber

abstract:
The increasing demand on user rates in the fifth generation (5G) requires network architectures
that can support high data rates with acceptable reliability. In order to increase
the data rates in the presence of the current spectrum crisis, shrinking cells and reusing the
spectrum is a proposed solution. Conventional implementation of dense cells requires a
large number of expensive BSs to locally process and decode users’ signals. Another limiting
factor that degrades the performance in a dense network is the inter-cell interference.
A cloud radio access network (CRAN) is a promising solution to those cost, complexity,
and interference challenges. A typical CRAN architecture consists of simplified low-cost
base stations (BSs), termed radio units (RUs), that collect the radio frequency (RF) user
equipments’ (UEs) signals and forward them over the fronthaul links to the central office
(CO) where signal processing is done over shared resources. Besides the reduced cost and
complexity of a CRAN, the joint processing at the CO enables joint interference mitigation
techniques. However, the performance of CRANs depends critically on the availability of
reliable fronthaul links with large bandwidth that may be expensive. Analog optical fronthaul
links provide high data rates at lower cost and complexity since UEs’ signals are
optically analog-modulated without digitalization, however, they suffer from other channel
impairments and nonlinearities.
In this thesis, analog optical fronthaul topologies are considered in which radio signals are forwarded over free-space optical (FSO) links, termed radio-over-free-space optical
(RoFSO) links, and optical fiber (OF) links, termed radio-over-fiber (RoF) links.
Firstly, a CRAN with mixed RF/RoFSO fronthaul is considered to investigate the performance
improvement when RF fronthaul links are replaced one-by-one by RoFSO links.
A novel joint optimization problem is introduced for the given architecture in which the
weighted sum of UEs’ rates is maximized by jointly designing RF and RoFSO links. The
optimization problem is solved over different numbers of RF and RoFSO links and under
various weather conditions. Under favorable weather conditions, the replacement of 1 RF
link by a RoFSO link is shown to increase the 50th percentile of UEs’ rates by 7 times.
Secondly, the reliability of a CRAN with two-hop RoFSO/RoF fronthaul links is derived
along with other performance metrics such as the average bit-error rate and the cumulative
distribution function of UEs’ rates. For the given architecture, the Gaussian noise
model of fiber nonlinearity is applied and an optimal OF average optical power is derived
to minimize the outage probability. Using the optimal power, and under favorable weather
conditions, the 50th percentile of user rate exceeds 1:5 Gbps.
Finally, a CRAN with passive all-optical two-hop fronthaul links is considered where
optical signals from the first RoFSO fronthaul hop are passively coupled into the RoF fronthaul
link. The fronthaul outage probability is derived in the context of network planning
to provide guidance on designing a set of system parameters. Those parameters include
coverage area radius, density of RUs, RoFSO gain, RoFSO optical power and RoF length.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract:
The upcoming generation of wireless communications, termed fifth generation (5G), promises
faster data rates and lower latency. In order to achieve this, more base stations (BSs) have
to be deployed which increases the cost and complexity of the network. A solution to
this challenge is to install simple BSs, i.e. radio units (RUs), that collect signals from
users and forward them to a central office (CO) for joint processing which is referred to
as a cloud radio access network (CRAN). The fronthaul network in a CRAN connects the
RUs to the CO and it can be implemented using different kinds of links. While there are
several fronthaul media (e.g., radio frequency (RF), free-space optical (FSO) links, copper
lines, satellite communications, and optical fiber (OF)), optical links provide high data
rates that are promising to achieve the 5G requirements. In this thesis, a novel architecture
of a CRAN is considered in which analog optical links, namely FSO links and OF
links, are used for fronthauling. Performance improvement in terms of rate and reliability
is investigated and optimized through different design tools. In response to the challenges
introduced by the proposed architecture, such as the nonlinearities of analog FSO and OF
links, various design parameters are proposed in the optimization problems to tackle those
challenges. Furthermore, a network planning framework is introduced to provide guidance
and insights on designing the network.


title: Medical Student Mistreatment:  A Journey

contributor:
Vanstone, Meredith
Health Science Education

subject:
medical education
mistreatment
medical student

abstract:
Background:  Over 50% of Canadian medical students report experiencing mistreatment, yet only a small proportion of students report these concerns to administration. It is unknown how medical students make sense of their experiences of mistreatment and come to decide about formally reporting these experiences. Improved understanding of this phenomenon will facilitate changes at the administrative and institutional levels to better support students.
Methods:  This Constructivist Grounded Theory study interviewed 19 current and former medical students from one institution about their experiences with mistreatment and reporting.  Anonymized transcripts were reviewed, coded and theory was developed.
Results:  Students undergo a journey surrounding experiences of mistreatment in five phases:  Situating, Experiencing and Appraising, Reacting, Deciding, and Moving Forward.  Students move through these phases as they come to understand their position as medical learners and their ability to trust and be safe within this institution.  Each experience of mistreatment causes students to react to what has happened to them, decide if they will share their experiences and reach out for support.  They choose if they are going to report the mistreatment, at what cost and for what outcomes.  Students continue through their training while incorporating their experiences into their understanding of the culture in which they are learning and continually resituating themselves within the institution.
Discussion:  This study revealed institutional mistrust from students especially as it related to reporting mistreatment.  Interventions designed to support students and decrease exposure to mistreatment may be best focused on increasing organizational trust and organizational compassion between students and the medical school.  Students volunteered mechanisms of support and to improve the reporting process.  Medical school administration should consider how they can increase trust with their learners while identifying areas of concern and procedures for intervening and providing more transparent resolutions.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: More than half of all Canadian medical student experience mistreatment during their medical school but very few choose to formally report it.  In this study we explored how students experienced mistreatment and their decisions about reporting it as well as what supports would be most helpful for them.  To better understand this issue, 19 medical students were interviewed about their experiences.  The interviews were analyzed through constructivist grounded theory and the identified themes were used to develop a theory of how students experience mistreatment and make decisions around reporting.  Students go through five phases:  Situating themselves in their learning environment, Experiencing and Appraising mistreatment, Reacting to that mistreatment, Deciding about reporting and the risks and benefits and Moving Forward within the same medical school as they continue.  Students showed mistrust towards the medical school and suggested changes the medical school could make to better support them.


title: Nanomechanical Dependence of Micelles on Salt Loading Ratios: A Story of Salt Complexation, Micellar Stability, and Nanoparticle Spatial Distribution

contributor:
Turak, Ayse
Engineering Physics

subject:
reverse micelles
Young's modulus
nanoparticles
salt complexation

abstract: Nanoparticles have been found to have an increasingly wide range of applications including drug delivery systems, chemical sensors, biomolecule sensors, single electron devices, catalysis, Li-ionbatteries, andsolarcells. Avarietyofmethodshavebeenused to produce nanoparticles, but one widely used approach is the application of reverse micellenanoreactorswherebyblockco-polymersareusedtoencapsulateprecursorsalts and serve as a vessel for precursor salts to react. As the encapsulation of precursor salts can be a multi-step process, some nanoparticle formulations have proven diﬃcult to make within the reverse micelle nanoreactor. To fully understand the diﬃculties in nanoparticle formation, we need to have a method to probe the internal structure of the reverse micelle. This thesis presents a novel method for probing the internal structure of the reverse micelle using a quantitative mechanical mapping (QNM) mode for atomic force microscopy (AFM). Unloaded reverse micelle nanoreactors were analyzed using the QNM AFM mode. A decrease of the Young’s modulus was noted through the centroid of the reverse micelle. Many models were applied to describe the noted decrease of Young’s modulus. The end result indicated that intrinsic diﬀerences between the mechanical properties of polystyrene and poly(2vinyl pyridine) and the co-polymer orientation lead to the measured decrease in Young’s modulus through the centroid. Results from the unloaded case were used to explain changes to the reverse micelle nanoreactor after loading with precursor salts. Across all precursor salts similar trends were noted, however there was no consistent relative Young’s modulus or molar salt loading ratio noted within the trends. Three distinct loading zones were consistent acrosstheprecursorsalts. Region I wastypiﬁedbyaslightdecreaseinrelativeYoung’s modulus with small resultant nanoparticles. Region II was typiﬁed by linear increases in relative Young’s modulus for increases in the molar salt loading ratio. Region III was found to have two possible outcomes, either the micelle reach a maximum eﬀective inﬁltration, where the relative Young’s modulus ratio no longer increases for increased molar salt loading ratio, or the micelle would unravel for increased molar salt loading ratio. Further studies should be done to conﬁrm the existence of the universal loading regions across further co-polymers, solvents, and precursor salts.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Dynamic Fidelity Susceptibility and its Applications to Out-of-Equilibrium Dynamics in Driven Quantum Systems

contributor:
O'Dell, Duncan
Sorensen, Erik
Physics and Astronomy

subject:
Quantum Dynamics
Quantum Phase Transitions
Universal Dynamics
Fidelity Susceptibility
Adiabatic
Dynamic Fidelity Susceptibility

abstract:
In this thesis we introduce a new quantity which we call the dynamic fidelity susceptibility
(DFS). We show that it is relevant to out-of-equilibrium dynamics in many-particle quantum
systems, taking the problem of an impurity in a Bosonic Josephson junction, and the
transverse field Ising model, as examples. Both of these systems feature quantum phase
transitions in their ground states and understanding the dynamics near such critical points
is currently an active area of research. In particular, sweeping a system through a quantum
critical point at finite speed leads to non-adiabatic dynamics. A simple theoretical tool
for describing such a scenario is the celebrated Kibble-Zurek theory which predicts that the
number of excitations is related to the speed of sweep via the phase transition’s critical exponents
at equilibrium. Another theoretical tool, useful in describing the static properties of
quantum phase transitions, is the fidelity susceptibility. Our DFS generalizes the concept of
fidelity susceptibility to nonequilibrium dynamics, reproducing its results in the static limit,
whilst also displaying universal scaling properties, akin to those found in Kibble-Zurek theory,
in the non-adiabatic regime. Furthermore, we show that the DFS is the same quantity as
the time-dependent quantum Fisher information which provides a measure of multi-partite
entanglement, as well as being closely related to out-of-time-order correlators (OTOCs).

abstract: Thesis

abstract: Master of Science (MSc)


title: One Indigenous Community's Journey Towards Water Security: A Transdisciplinary Reflection on Drinking Water Advisories and Pathways Forward

contributor:
Dickson-Anderson, Sarah
Schuster-Wallace, Corinne
Health Research Methodology

subject:
First Nations
Indigenous
Drinking Water
Water Advisories
Community-Based Participatory Research
Traditional Knowledge
Canada

abstract:
Background: Water quality in on-reserve Indigenous communities in Ontario is concerning, with issues ranging from deteriorating water quality to issues with regulation and support. As a result, many communities are placed under a Drinking Water Advisory (DWA), which, at its most severe, indicates water is not safe for use or consumption. Between 2004 and 2013, approximately 70% of all on-reserve communities in Ontario were under at least one DWA. While designed to protect physical health, DWAs have widespread impacts on health and wellbeing. However, little is known about First Nation individuals’ thoughts, feelings, and experiences living under a DWA.
Purpose: To unpack and explore the broad impacts of a Boil Water Advisory (BWA) from the perspective of community members on a reserve in Northern Ontario and provide considerations for current and future BWA management.
Methods: Methodological choices were driven by the principles of community-based participatory research. Questionnaires and interviews were used to collect data. Two hundred and twenty-six questionnaires were distributed. Fifteen Elders and 22 key informants (KIs) were contacted for an interview.
Results: Forty-four (19.5%) individuals completed a questionnaire. Eight Elders and 16 KIs participated in 20 interviews. Questionnaire sections were used to frame the data analysis, which fell under five major themes: 1) Community Context; 2) Knowledge of BWAs; 3) Living Under a BWA; 4) Water and Health; and, 5) Pathways Forward.
Conclusions: Responses illuminated gaps where education surrounding best practices for protecting health would be crucial moving forward. They also highlighted that women are an important target audience for education. Points also emerged where communication with community members and stakeholders would be key to understanding the impacts and outcomes of DWAs. Additionally, this community, and others experiencing a DWA, should consider greater involvement in water management by younger individuals, to ensure that all perspectives are adequately represented.

abstract: Thesis

abstract: Master of Public Health (MPH)

abstract:
When water is known, or suspected, to be unsafe for human consumption, communities are placed under a Drinking Water Advisory (DWA). Indigenous communities have some of the worst water quality in Canada and many are subsequently under DWAs. Despite the widespread impact of DWAs on health and wellbeing, little is known about First Nation individuals’ thoughts, feelings, and experiences living under one.
The goal of this thesis was to unpack and explore the broad health, social, cultural, and economic impacts of a Boil Water Advisory (BWA) from the perspective of community members on a reserve in Northern Ontario and provide considerations for BWA management.
Responses pointed to gaps where education surrounding how to best protect health would be crucial, especially for women who were highlighted as an important target audience. Points also emerged where communication would be key to understanding the impacts and outcomes of DWAs moving forward.


title: New Strategies for Data Acquisition in Electron Ptychography: Energy Filtering and Reduced Sampling

contributor:
Botton, Gianluigi
Materials Science and Engineering

subject: Electron Ptychography

subject: Transmission Electron Microscopy

subject: Sampling

subject: Diffraction Imaging

subject: Phase Retrieval

subject: Scanning Transmission Electron Microscope

abstract: Electron Ptychography is a technique to retrieve the phase information of the medium through which the electron wave travels in a Transmission Electron Microscope (TEM). Phase calculation is carried out by acquiring an oversampled dataset of diffraction patterns from the sample and execution of a Fourier-based mathematical solution or algorithm using the collected dataset of intensity patterns. The phase of the electron wave contains valuable information about the structure of the material under study. In this contribution, we provide a scientific background necessary for understanding the phase calculation method, examine the capabilities and limitations of the Electron Ptychography in experimental setup and introduce two novel methods to increase the signal to noise ratio by using the same dose budget used in a classic Ptychography experiment.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Cognitive Dynamic System for Connected and Autonomous Vehicles

contributor:
Haykin, Simon
Computational Engineering and Science

abstract:
As an essential part of the emerging people-centric Internet of Things, connected and autonomous vehicles (CAVs) have the potential to reshape future transportation systems and impact the physical and/or social environment. While CAVs are currently being developed all over the world, they are unfortunately faced with various potential threats that could endanger the entire CAV network. Among others, risk-related concerns such as motion perturbation and jamming attacks are extremely critical to the survival of CAV networks and urgently need effective countermeasures.
This research addresses the aforementioned challenges by employing cognitive dynamic systems (CDS). Inspired by certain features of the human brain, CDS is a very powerful research tool to study complex systems operating in an open and possibly adversarial environment. As a special function of CDS, cognitive risk control (CRC) actualizes the concept of predictive adaptation to bring risk under control when encountered with unexpected uncertainty.
The primary research objective of this thesis is to apply CDS to CAV networks with emphasis on improved driving safety and system security. The function of CRC is utilized in respective vehicular systems in order to achieve robust target-tracking and anti-jamming vehicle-to-vehicle communication performance. For validation, extensive simulation results have shown that the proposed methods have desirable performance in the face of motion perturbation and/or jamming attacks under various scenarios.
This thesis contributes to the body of knowledge by presenting the following four achievements: the first theoretical work that integrates the research tool of CDS with the engineering application of CAVs; the first experimental work of CRC being applied to a practical vehicular system; the first experimental work on V2V communication that involves anti-jamming, power control, and channel selection at the same time; and a brand-new design of coordinated vehicular radar and communication systems that builds upon all the research efforts made previously.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: As an essential part of the emerging Internet of Things, connected and autonomous vehicles have the potential to reshape future transportation systems and change the commute style in people's everyday life. Unfortunately, they are typically faced with various threats and attacks that could endanger the entire vehicle network. The recent development of cognitive dynamic systems has provided a very powerful research tool to study complex systems operating in an open and possibly adversarial environment. The key goal of this thesis is to apply cognitive dynamic systems to connected and autonomous vehicles with emphasis on improved driving safety and system security. The function of cognitive risk control is utilized in respective vehicular systems in order to achieve robust target-tracking and anti-jamming vehicle-to-vehicle communication performance. For validation, extensive simulation results have shown that the proposed methods have desirable performance in the face of motion perturbation and/or jamming attacks under various scenarios.


title: Towards Safer X-rays

contributor:
Shirani, Shahram
Electrical and Computer Engineering

abstract:
High-intensity X-ray radiation through the human body can cause damage to cells,
increasing the chance of complications such as cancer. A possible solution is lowering
the dosage of radiation. In low dose CT (LDCT) images, fundamental structures are
still easily identifiable. However, noise and other additional artifacts are introduced.
Removing the visual effects of artifacts caused by lowering radiation dose has been an
active area of research in the last few years. Recently, deep learning approaches have
demonstrated impressive performance for LDCT denoising. In this thesis, we propose a
new machine learning-based approach for LDCT noise reduction that outperforms other
methods.
Deep Learning is based on the idea of stacking many layers of neurons together. Over
the past years, deep learning researchers have successfully optimized the performance
of neural networks by stacking more layers. With the growing availability of high performance GPUs as well as more massive datasets, deep learning technology has proven
very useful. However, deeper networks are more challenging to train, not because of their
computational cost, but due to the difficulty of propagating gradients through so many
layers.
Deeper neural networks are more complex to train. We present a residual framework
to ease the training of networks that are substantially deeper than the others. Residual
learning means each subsequent layer in a deep neural network is only responsible for,
fine-tuning the output from a previous layer, which is possible only by adding a learned
"residual" to the input. This method differs from a more traditional approach where
each layer had to generate the total desired output. By using residual learning in LDCT
denoising, we prevent degradation of training accuracy once traversing the network and,
increase the training pace. Another aspect of our work is using Generative Adversarial Network (GAN), which
is a framework for estimating generative models via an adversarial process. We simultaneously train two models a generative model G, that we are using for generating Normal Dose CT (NDCT) and a discriminative model D that estimates the probability that a
sample came from the training data rather than G. GANs’ potential is enormous since
they can learn to mimic any distribution of data.
The novelty of our approach is in combining Residual learning and GAN. For training
a convolutional neural network (CNN), a large amount of data is needed. We address this
problem by using patch coding. Inspired by the idea of deep learning, we combine the
autoencoder, deconvolutional network, and skip connections into residual learning. One
motivation for skipping over the layers is to avoid the problem of gradient vanishing. Our
experiments show that our method outperforms recent works on LDCT image denoising
in terms of Peak SNR (PSNR), and SSIM.

abstract: Thesis

abstract: Master of Electrical Engineering (MEE)


title: The Social Organization of Perinatal Care for Women Living with HIV in Ontario: An Institutional Ethnography

contributor:
Greene, Saara
Social Work

subject:
HIV
women
institutional ethnography
perinatal care

abstract: My doctoral research begins from the standpoint of pregnant women and mothers living with HIV in Ontario, Canada and explores the concerns that women living with HIV have as they navigate healthcare during pregnancy, childbirth, and early postpartum. Moving beyond a description or abstracted theorization of women’s experiences, I have used institutional ethnography to explicate how women’s concerns are connected to and organized by ruling relations such as the ideological discourses that underpin the work practices of healthcare providers operating within healthcare institutions. This dissertation follows three “threads” that were discovered in the overall institutional ethnographic inquiry, and that form the basis of three manuscripts. The first thread (Chapter Three) focuses on HIV disclosure, which all women who participated in this research expressed as a concern, and uncovers how the issue of HIV disclosure is accounted for in healthcare providers’ work activities. In this analysis, I show how both the women’s and healthcare provider’s concerns about and actions related to HIV disclosure are connected to discourses such as “fear of contagion” and “AIDS hysteria” that continue to permeate public consciousness. The second thread (Chapter Four) focuses on the discourse of “risk” as organizing women’s experiences and healthcare providers’ work, which became visible through medications women were prescribed, the prenatal clinic appointment schedule women were expected to follow, and the medical interventions that were applied to women’s bodies during childbirth and early postpartum. In a third line of inquiry (Chapter Five), I outline how the current organization of “high-risk” maternity care that is delivered by specialists and is located in regional hospitals has particular implications for women’s pregnancy and motherhood experiences, especially for women who live at a distance from these services and/or find it challenging to attend appointments because of employment and familial responsibilities. This analysis shows how the discourses of “risk” and “safety” are differently known and enacted by women and their healthcare providers, and calls into question the classification of pregnancies of women living with HIV as “high-risk.” In following the three threads and tracking the territory of perinatal care for women living with HIV, I illuminate points of disjuncture between women’s and healthcare providers’ ways of knowing HIV in the context of pregnancy and childbirth, and identify possibilities for how healthcare practices can be augmented to respond to the concerns and challenge that women expressed. In the Conclusion chapter, I draw attention to the tensions between the meta-level ideological discourses of “HIV exceptionalism” and “HIV normalization” that run through Chapters Three, Four, and Five, and that are generalized across the HIV and maternity care services that women living with HIV encounter. I end this dissertation with my thoughts regarding implications for the organization of perinatal care for women living with HIV in Ontario.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)

abstract: In Ontario, the maternity care that women living with HIV receive during pregnancy, childbirth, and early postpartum (also known as the perinatal period) is located in “high-risk” clinical settings within regional, academic teaching hospitals. The organization of such care has important implications for women’s daily lives. This inquiry begins from the personal experiences of pregnant women and mothers living with HIV in Ontario and explores the concerns that women have as they navigate HIV and maternity care during the perinatal period. The inquiry shows how the troubles that women face are produced through institutional conditions and the routine practices of healthcare providers. This dissertation also examines how institutional arrangements related to reducing the risk of HIV to the fetus and infant, and lingering fears about HIV as “contagion,” shape women’s care experiences. Implications for the organization and delivery of perinatal care to women living with HIV is discussed.


title: Molecular Regulation of Follistatin by Caveolin-1 in Glomerular Mesangial Cells and its Therapeutic Potential in Chronic Kidney Disease

title: The Therapeutic Role of Follistatin in Chronic Kidney Disease

contributor:
Krepinsky, Joan
Medical Sciences

subject:
Renal Fibrosis
Activin
Follistatin
Chronic Kidney Disease

abstract: Chronic kidney disease (CKD) is a major cause of morbidity and mortality, affecting more than 10% of the world’s population. CKD is associated with excessive renal fibrosis, which leads to declining kidney function and eventual kidney failure. In CKD, glomerular mesangial cells (MC), resident fibroblasts and tubular epithelial cells undergo phenotypic activation and transition in response to profibrotic and proinflammatory cytokines such as transforming growth factor β1 (TGFβ1). These activated renal cells excessively produce extracellular matrix (ECM) proteins that replace functional renal tissue and lead to renal fibrosis. Caveolae are small omega-shaped invaginations of the plasma membrane that mediate signaling transduction events. Formation of caveolae require the protein caveolin-1 (cav-1). We have previously shown that the ability of MC to produce matrix proteins is dependent on cav-1 expression. Unfortunately, clinically targeting cav-1 within the kidneys, specifically within MC, is technically challenging and as of yet unfeasible. Thus, to better understand how cav-1 deletion is protective, we carried out a microarray screen comparing cav-1 wild-type (WT) and knockout (KO) MC. Here, we discovered significant up-regulation of a TGFβ superfamily inhibitory protein, follistatin (FST). FST specifically targets and neutralizes activin A (ActA) but not TGFβ1. TGFβ1 and ActA both belong to the TGFβ superfamily of cytokines and growth factors. While TGFβ1 itself is a known key mediator of renal fibrosis, therapies aimed at directly inhibiting TGFβ1 in kidney diseases have not been successful due to opposing profibrotic and anti-inflammatory effects. ActA has been shown to act as a strong profibrotic and proinflammatory agent in various organs, including the lungs and liver. We along with others have observed elevated levels of ActA within the kidneys and serum of mice and humans with CKD. Functionally, ActA has been shown to contribute to ECM production in the kidneys. Hence, we hypothesized that ActA inhibition through FST could prove beneficial in CKD. In this thesis, our first study elucidated a novel molecular pathway by which cav-1 regulates expression of the FST in MC. Our results indicate that FST is negatively regulated by cav-1 through a PI3K/PKC zeta/Sp1 transcriptional pathway. Our second study expands on these findings and tests whether exogenous FST administration protects against the progression of CKD in a surgical mouse model of CKD. Here, we discovered that FST acts as a reactive oxygen species (ROS) scavenger and that exogenous administration of FST protects against the development of CKD through the inhibition of renal fibrosis and oxidative stress. Lastly, our third study determined whether microRNAs (miRNAs) are implicated in post-transcriptionally regulating FST through cav-1 and whether these FST-targeting miRNAs can be utilized therapeutically to protect against the development and progression of CKD. Here, we determined that a FST-targeting miRNA, microRNA299a-5p, is significantly downregulated in cav-1 deficient MC, upregulated in vivo in a mouse model of CKD and that its inhibition, in vitro and in vivo protects against the accumulation of ECM proteins and renal fibrosis. These studies collectively suggest that FST is an effective therapeutic option for the management of CKD.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Chronic kidney disease results from excessive fibrosis (scarring) within the kidneys. The goal of this thesis is to understand the molecular mechanisms involving the regulation of an antifibrotic protein, follistatin, in glomerular mesangial cells and to identify its therapeutic potential in chronic kidney disease. This thesis has identified that follistatin, an endogenous inhibitor of the profibrotic cytokine activin A, is regulated transcriptionally by Sp1 and post-transcriptionally by microRNA299a-5p. Furthermore, this thesis has demonstrated that exogenous recombinant follistatin administration protects against the progression of chronic kidney disease and that microRNA299a-5p targeting may be an alternative approach to block renal fibrosis. These studies collectively show that follistatin is an effective treatment for the management of chronic kidney disease.


title: Interval Versus Continuous Single-leg Training on Capillarization and the Satellite Cell Response

contributor:
Parise, Gianni
Kinesiology

subject:
exercise physiology
satellite cells
capillarization
interval training

abstract: Skeletal muscle satellite cells (SC) are essential in muscle repair and regeneration. The role of SCs in mediating hypertrophic adaptations following resistance training has been widely studied. Recent evidence from endurance training studies suggest that SCs may also play a role in mediating non-hypertrophic adaptations. Indeed, it has been shown that satellite cells respond to endurance training. Work in rodent models suggest that exercise intensity may play an important role in expanding the SC pool whereas the results of endurance training studies in humans are much less consistent. Limited evidence also suggest that exercise intensity may be important in mediating exercised-induced capillarization following endurance training in humans. In both instances, it is unknown whether the on-and-off pattern characteristic of interval training (i.e. the rest-work cycles) plays a role in the magnitude of these skeletal muscle responses to this type of exercise. Thus, we sought to determine if the rest-to-work cycle plays a role in the scope of these skeletal muscle responses by comparing the SC response and capillarization to two distinct work-matched protocols that are performed at the same intensity but at two different exercise patterns (interval versus continuous). We hypothesized that interval exercise will elicit a greater SC response and induce greater capillary growth compared to work-matched continuous exercise. Ten young active individuals performed 12 sessions of counterweighted single-leg cycling over 4 weeks. Each leg was randomly assigned to Interval (INT) (10 x 3-min intervals at 50% of single leg peak power output (PPO), with 1 min recovery) or Continuous (CONTIN) (30 min at 50% PPO, followed by 10 min recovery), which were performed 5 min apart on each day, in an alternating order. Resting muscle biopsies were obtained from the vastus lateralis pre- and post-training. Immunofluorescent microscopy of muscle cross sections was used to assess muscle fibre capillarization, SC expansion and activation. Western blot analysis was performed on pro-angiogenic factors, specifically VEGF and VEGFR2. Mixed muscle SC activation increased in the INT leg compared to the pre-training time-point (3.2 ± 0.5 vs. 1.5 ± 0.2 Pax7+/MyoD+ cells/ 100 myofibers, respectively; P < 0.05). Mixed muscle SC activation did not increase significantly in the CONTIN leg compared to the pre-training time-point and there was no significant difference in activation between CONTIN and INT post-training. With regards to capillarization, no differences in type I or type II muscle fibre CC (capillary contacts), C/Fi (individual capillary-to-fibre ratio) or CFPE (capillary-to-fibre perimeter exchange index) were observed post-training or between legs. No significant expansion of the SC pool occurred in either legs post-training and no increases in fibre cross-sectional area was observed. This study presents novel evidence of mixed muscle SC activation following interval exercise training that is not observed following work- and intensity-matched continuous exercise training. This suggest that the rest-to-work cycle associated with interval exercise may dictate, to some extent, SC activation whereas it may not be a primary stimulus for training-induced changes in capillarization.

abstract: Thesis

abstract: Master of Science (MSc)


title: The NLRP3 inflammasome is involved in statin-induced insulin resistance

contributor:
Schertzer, Jonathan
Biochemistry and Biomedical Sciences

subject: Statin

subject: NLRP3

abstract: Statins are one of the most widely prescribed drug classes because they lower circulating low density lipoprotein-cholesterol (LDL) and reduce the risk of cardiovascular events. Statin-mediated inhibition of HMG-CoA reductase also lowers substrates required for protein prenylation. This cholesterol-independent effect of statins can alter immune function. Lower protein prenylation can increase IL-1β. This pro-inflammatory cytokine can promote insulin resistance, which may be a factor in the recent evidence linking statins to increased incidence of diabetes. IL-1β is unique compared to most cytokines because it can be regulated by the NLRP3 inflammasome. In this thesis, we discovered that statins promote NLRP3-dependent insulin resistance in adipose tissue. We next hypothesized that statin-induced lowering of protein prenylation activated the NLRP3/Caspase-1 inflammasome, which would cause IL-1β-dependent insulin resistance in adipose tissue. We showed that atorvastatin impaired insulin signalling in adipose tissue from WT, but not IL-1β-/- mice. Treatment with a caspase-1 inhibitor prevented atorvastatin-inhibition of insulin signalling. The isoprenoid, Geranylgeranyl pyrophosphate (GGPP) also prevented atorvastatin-induced defects in insulin signalling. Interestingly, atorvastatin- inhibition of insulin action was associated with decreased insulin-stimulated lipogenesis in both white adipose tissue and 3T3-L1 adipocytes. The findings in this thesis suggest a statin-induced reduction in isoprenoids, required for protein prenylation production, impairs insulin action via IL-1β derived from activation of NLRP3/Caspase-1 inflammasome in adipose tissue.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Statins are one of the most widely prescribed drugs and used in the treatment of cardiovascular disease. Statins lower LDL often called bad cholesterol. However, some patients experience side effects such as higher blood glucose and increased risk of type 2 diabetes. Type 2 diabetes is generally preceded by insulin resistance and this period of “prediabetes” is reversible. Inflammation is one factor involved in insulin resistance and in the development of type 2 diabetes. In this thesis, we discover that statins activate an inflammatory response known as the NLRP3 inflammasome, which leads to insulin resistance, particularly in fat tissue. Activation of this inflammasome by a statin, did not require lower cholesterol, but increased the inflammatory cytokine IL-1b, which was the key factor leading to insulin resistance in fat tissue. Inhibition of the NLRP3 inflammasome or IL-1b may prevent insulin resistance and risk of type 2 diabetes in people taking statins.


title: ASSESSMENT OF CORROSION BEHAVIOUR OF MACHINED SUPER DUPLEX STAINLESS STEEL OBTAINED WITH THREE DIFFERENT PVD COATED TOOLS

contributor:
Veldhuis, Stephen
Mechanical Engineering

subject:
Super duplex stainless steel
Machining
Corrosion
PVD coatings

abstract: Super Duplex Stainless Steels (SDSS) are widely used in offshore oil and gas industrial components. They are dual phase materials consisting of ferrite and austenite in similar ratios with high contents of chromium and presence of molybdenum. This combination of microstructure and chemical composition results in enhanced mechanical strength and corrosion resistance. However, this material has poor machinability, exhibiting the following characteristics: (i) tendency to strain-harden; (ii) extreme adhesive behaviour; and (iii) high cutting temperatures. These circumstances not only result in high tool wear rates, but also lead to poor surface integrity due to the work hardening effect, high roughness and tensile residual stress. To minimize these detrimental effects, PVD coating technologies have been widely applied to cutting tools due to their tribological properties exhibited during cutting, which reduce friction and diminish heat. In this work, three different PVD coatings were tested during the turning of super duplex stainless steel of grade UNS S32750. In addition to the tool performance, surface integrity was assessed by surface texture analysis, residual stresses and hardness profile. The electrochemical behaviour of the machined surface was evaluated by potentiodynamic anodic polarization measurements. Stress cracking corrosion (SCC) tests were also performed. Results indicate a relationship between the tool performance and surface electrochemical behaviour, where the tool with best cutting performance, AlTiN, also presented the best electrochemical behaviour. Stress cracking corrosion was found to be associated with residual stresses on the workpiece, among the three tested PVD coated tools the AlCrN/TiSiN showed lowest tensile residual stresses and lowest SCC susceptibility. The surface generated by AlTiN coated tool presented the highest levels of tensile residual stresses, resulting in a higher SCC susceptibility.

abstract: Thesis

abstract: Master of Applied Science (MASc)