title: HELMET NON-INVASIVE VENTILATION IN ACUTE RESPIRATORY FAILURE: A SYSTEMATIC REVIEW, CASE SERIES AND PILOT FEASIBILITY TRIAL

contributor:
Rochwerg, Bram
Health Research Methodology

subject: non-invasive ventilation

abstract:
This thesis consisted of three related studies presented as three separate manuscripts (one published in a peer-reviewed journal, one submitted for publication to a peer reviewed journal and one ongoing). The overarching theme of this thesis was to assess helmet non-invasive ventilation (NIV) as a new modality of NIV for the treatment of acute respiratory failure in the intensive care (ICU) setting.

Our first manuscript is a published systematic review and meta-analysis that compared helmet NIV to facemask NIV and high flow nasal cannula (HFNC) in adult patients with acute respiratory failure. We performed an extensive search and included 16 randomized control trials (RCTs) and 8 observational studies, the results of which we pooled separately. We assessed certainty of evidence using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach. Pooled data from RCTs suggested that helmet NIV may reduce mortality and intubation when compared to facemask NIV, albeit based on low certainty evidence. Data from observational studies supported this finding but were of even lower certainty.

Given the above findings, we concluded that a large randomized control trial (RCT) that compared helmet to facemask NIV for patients with acute respiratory failure (ARF) is needed. Since helmet NIV is a new technology, before embarking on this large trial, we recognized that it was necessary to establish familiarity with the device and conduct a pilot feasibility trial. Manuscript # 2 was a 16 patient case series that characterized introduction of the helmet NIV at 2 centres (one in Canada and one in the United States). All patients who were admitted with ARF over  a 7 month time period and for whom the clinical team determined that helmet NIV may be beneficial were enrolled in the trial. The most common reason for helmet NIV usage was pneumonia, especially due to COVID-19. Most patients tolerated helmet NIV and no adverse events were recorded with the device. This case series has been submitted to a peer reviewed journal for review.

After the case series had concluded and staff were introduced to helmet NIV, we initiated an ongoing single centre pilot feasibility RCT comparing helmet to facemask NIV in patients with ARF (manuscript #3). This pragmatic, unblinded, concealed allocation, parallel-group trial is currently being implementedat the Juravinski Hospital and will include 50 patients. The pilot trial will examine feasibility outcomes includingrecruitment rate and protocol adherence rate. While still ongoing, current feasibility goals have been met, although we noted a high crossover rate and decreased enrollment during the peak of the most recent COVID wave. These considerations have necessitated modifications to the protocol including planned enrollment of a second site, increased site education and new incentives for healthcare workers to enroll patients in the study. Funding for this trial was provided by securing  2 peer reviewed grants totalling $75,000.

Together, all 3 manuscripts represent an ongoing, cohesive research program aimed at assessing implementation and adoption of new technology in the ICU. Further projects examining the cost-effectiveness of this new technology, qualitative patients and healthcare worker experiences, as well as the aforementioned large multicentre RCT are planned moving forward.

abstract: Thesis

abstract: Master of Health Sciences (MSc)


title: Skeletal muscle remodelling under distinct loading states in young men

contributor:
Phillips, Stuart
Kinesiology

subject:
Skeletal muscle
Muscle atrophy
Muscle hypertrophy
Mechanisms
Muscle protein turnover
Ultrasound imaging

abstract: Skeletal muscle is a plastic tissue capable of responding to environmental perturbations. Increased loading via resistance exercise (RE) activates muscle protein synthesis (MPS) and, to a lesser extent, muscle protein breakdown (MPB). The ingestion of protein further stimulates MPS and suppresses MPB, inducing a positive net protein balance and protein accretion – i.e., muscle hypertrophy. In contrast, muscle unloading reduces MPS, which is thought to be the key driver underpinning skeletal muscle atrophy. The degree of muscle hypertrophy and atrophy in response to loading and unloading varies significantly between individuals and provides an opportunity to investigate the molecular regulators of skeletal muscle remodelling. To that end, we developed a novel unilateral model in which one leg was subjected to RE to induce hypertrophy (Hyp) and the contralateral limb was immobilized to induce atrophy (At). In study 1, we characterized the morphological changes induced by our HypAt model and validated the use of ultrasonography to measure changes in muscle size in both limbs. We discovered that by assessing the differential change in muscle size between legs we reduced the coefficient of variation between subjects. This enabled a more in-depth means-based characterization of the molecular regulators of skeletal muscle remodelling. Indeed, we discovered significantly more genes regulated by muscle remodelling than similarly-sized studies. We also identified a transcriptional signature that scaled with lean mass gains in three independent cohorts and included RNA species that were only modulated at their untranslated regions. Finally, in study 3 we simultaneously measured MPS and MPB in response to short-term immobilization (4 days) and demonstrated for the first time that MPB is statistically unchanged by unloading. Taken together, these studies contribute significantly to our understanding of skeletal muscle remodelling under different loading states and provide a valuable hypothesis-generating resource for future research in the field.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Adaptations of skeletal muscle to loading and unloading are variable between individuals. Herein, we employed a unilateral approach to better understand the drivers of this variability by assessing the influence of resistance training (RT) and disuse on muscle protein turnover and gene expression. First, we validated the use of ultrasound for measuring changes in muscle size in response to loading and unloading. We then identified thousands of genes regulated by loading status and discovered many that were correlated with lean mass gain – some of which would not have been detected without our model. We also demonstrated that RT-induced increases in muscle protein synthesis were not associated with changes in muscle size; however, reductions in muscle protein synthesis were associated with the degree of muscle atrophy observed in response to disuse. Together, these studies contribute significantly to our understanding of how skeletal muscle size is regulated by muscle loading and unloading.


title: Sedimentation during Liquid Processing of Metal Matrix Composites

contributor:
Irons, G. A.
Engineering

subject: Liquid Processing, Sedimentation, Metal Matrix Composite, Metal alloy, electrical resistance, aluminum foundry alloy

abstract:
During the incorporation of ceramic particles into metallic alloy melts for the
production of metal matrix composites, the particles tend to float or sink, depending on their density. In order to study the sedimentation patterns, a novel electrical resistance technique has been developed. A current is passed between two electrodes, and the potential over a fixed distance is measured with two other electrodes. Experiments were carried out in an aluminum foundry alloy(A356) containing up to 30 volume percent 88 μm silicon carbide particles. The particles’ behaviour was compared with sedimentation patterns in aqueous systems. The implications for fabrication and remelting of metal matrix composite material are discussed.

abstract: Thesis

abstract: Master of Engineering (ME)


title: Siblings of youth with a disability during the transition to adulthood: A synthesis of resources and understanding of their experiences to support them in current and future roles

contributor:
Gorter, Jan Willem
Rehabilitation Science

subject: children, youth, siblings, patient-oriented research, program, case study, qualitative, knowledge synthesis, disability, healthcare transition

abstract:
As youth with disabilities age and transition to adulthood, they will often need to learn how to manage their healthcare. Siblings are members of the family who can provide support to their sibling with a disability, but their roles during transition have not been well described in the literature. Typically developing (TD) siblings identified that they require information and resources in their roles.
The overall objectives of the research studies  in this doctoral dissertation are: 1) to synthesize existing resources and programs to support TD siblings of individuals with a disability; and 2) to develop a deeper understanding about the experiences of TD siblings. The findings from these studies are summarized in six scholarly manuscripts prepared for peer review and publication. All studies were conducted in partnership with siblings with lived experiences.
Results from the review and qualitative document analysis of online resources to support TD siblings (Chapter 2) identified that limited resources are available to support TD siblings with healthcare management of their sibling with a disability. The scoping review (with the protocol described in Chapter 3 and results presented in Chapter 4) identified that programs for TD siblings are focused on knowledge development and skill acquisition for the TD siblings themselves or on empowerment by training TD siblings in skills that they can apply with their sibling with a disability. In addition to synthesizing existing knowledge, the qualitative study provided an in-depth understanding of the experiences of TD siblings (with the protocol described in Chapter 5) in two distinct areas: their roles and responsibilities (Chapter 6) and the influence of their sibling and family relationships on their identity formation during developmental stages (Chapter 7).
Overall findings from this dissertation suggest areas for future directions, including knowledge transfer to share synthesized resources with target audiences, co-creation of resources to support siblings in their roles, and enhancement of programs to involve siblings and the whole family.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)

abstract:
As youth with a disability transition to adulthood, many will assume greater responsibility for their own health management, activities often supported by family members, including siblings.
Little information is available about the roles that siblings have to their sibling with a disability in this process. Siblings have mentioned that they need information and resources for their roles. The purpose of this work is to summarize resources and programs in Canada and internationally for siblings, as well as better understand the experiences of siblings of an individual with a disability. The information from this work can be helpful by sharing the summary of resources with siblings and families, create new resources to support siblings of an individual with a disability, and build on programs that allow for siblings and the whole family to participate.


title: A Multimodal Approach to the Osseointegration of Porous Implants

contributor:
Grandfield, Kathryn
Materials Science and Engineering

subject:
bone
biomaterials
electron microscopy
additive manufacturing

abstract:
The field of implantology is centred around interfacial interactions with the
surrounding bone tissue. Assessing the suitability of novel engineering materials as
implants for clinical application follows a preliminary workflow that can be
simplified into three main stages: (i) implant design, (ii) in vitro compatibility, and
(iii) in vivo compatibility. This thesis is subdivided to mirror each of these three
themes, with a specific focus on the multiscale features of the implant itself as well
as appositional bone tissue. In Chapter 3, a biomimetic approach to generate porous
metallic implants is presented, using preferential seeding in a 3D Voronoi
tessellation to create struts within a porous scaffold that mirror the trabecular
orientation in human bone tissue. In Chapter 4, cytocompatible succinate-alginate
films are generated to promote the in vitro activity of osteoblast-like cells and
endothelial cells using a methodology that could be replicated to coat the interior
and exterior of porous metals. In Chapter 5, two types of porous implants with
graded and uniform pore size are implanted into rabbit tibiae to characterize the
biological process of osseointegration into porous scaffolds. In Chapter 6, these
same scaffolds are probed with high-resolution 2D and 3D methods using scanning
transmission electron microscopy (STEM) and the first-ever application of plasma
focused ion beam (PFIB) serial sectioning to observe structural motifs in
biomineralization at the implant interface in 3D. This thesis provides new
knowledge, synthesis techniques, and development of characterization tools for
bone-interfacing implants, specifically including a means to: (i) provide novel
biomaterial design strategies for additive manufacturing; (ii) synthesize coatings
that are compatible with additively manufactured surfaces; (iii) improve our
understanding of mineralization process in newly formed bone, with the ultimate
goal of improving the osseointegration of implants.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract:
Metallic implants are widely used in dental and orthopedic applications but can be
prone to failure or incomplete integration with bone tissue due to a breakdown at
the bone-implant interface as defined by clinical standards. In order to improve the
ability of the implant to anchor itself into the surrounding bone tissue, it is possible
to use novel three-dimensional (3D) printing approaches to produce porous metals
with an increased area for direct bone-implant contact. This thesis examines
strategies to design porous implants that better mimic the structure of human bone,
possible coating materials to accelerate early bone growth at the implant interface,
and the microscale-to-nanoscale origins of bone formation within the interior of
porous materials.


title: Examining the relationship between the “real world” adoption of digital health tools and primary care experience

contributor:
Costa, Andrew
eHealth

subject:
Digital health
Telehealth
Primary care
Electronic health records
Online appointment booking
Patient experience
Patient centeredness
Access to care
Quality care

abstract:
Background: Patient experience is a crucial measure of patient-centeredness and quality
care delivery. Digital health may contribute to patient experience by offering tailored and
accessible avenues of care.
Purpose: I explored how access to digital health, including telehealth, electronic health
records, and online booking, may be associated with improved primary care experience for
Ontario adults.
Methods: This cross-sectional study included Ontario adults (16 years or older) who
responded to waves 27 to 29 of the Health Care Experience Survey (HCES) between May
2019 and February 2020. Adults who did not see their primary care provider within the past
12 months or did not have a primary care provider were excluded. Outcomes included a
summed patient experience score derived from five HCES experience-related questions and
time to appointment for a health concern. Associations between outcomes and digital health
interventions were tested through chi-square tests and logistic regression while adjusting
for confounders and stratifying by health care utilization.
Results: 3,700 participants met the inclusion criteria, where 2204 remotely communicated
with their primary care provider (59.6%), 98 digitally accessed health records (2.6%), and
120 booked an appointment online (3.2%). We observed no significant associations
between digital health tools and patient experience or time to appointments through chi-square tests. Participants with over three primary care visits in the past year who accessed
online booking were 84% less likely to report poorer experience scores than participants
without online booking access [Adjusted OR 0.16, 95% CI 0.02 – 0.56, p < 0.05].
Participants with three or fewer primary care encounters who accessed online booking,
compared to the same reference group, were 72% less likely to report having a same or next
day appointment with their primary care provider [Adjusted OR 0.25, 95% CI 0.08 – 0.64,
p < 0.01]. Significant associations were observed between other sociodemographic factors
and patient experience and access to care outcomes.
Interpretation: The associations between digital health access and patient experience and
access to care were inconsistent across different analyses. Despite experimental studies
observing the benefits of digital health adoption in primary care, the effect is unclear in the
real-world context. Furthermore, drawing conclusions on the relationship between digital
health and quality care outcomes was limited due to the lack of adoption of digital health
before the COVID-19 pandemic. As digital health adoption grows, future research should
utilize the availability of further data to evaluate the effectiveness of digital health in
Ontario primary care.

abstract: Thesis

abstract: Master of Science (MSc)

abstract:
Patient outcomes such as experience and timeliness of care are frequently viewed as aims
of quality health care. Although past studies indicate digital health supports quality care,
the real-world effectiveness of digital health is underexplored in Ontario. This thesis
aimed to explore relationships between real-world use of digital health in Ontario and
primary care experience and access using survey data. This study found very few survey
respondents used digital health before the COVID-19 pandemic. The primary care
experience and access to care of adults who did use digital health did not differ very much
from adults who did not use the technology. Some outcomes differed in adults who
booked their primary care appointment online compared to those who did not; however,
the study could not conclude on the relationship. Other personal factors such as age and
residence area impacted the quality of primary care. This study was limited due to the
lack of digital health users. Future studies should explore digital health's impact on
patient outcomes beyond the pandemic.


title: Inhibition of Return is Depth-Specific, Object-Based, and Relies on a World-Centered Frame of Reference in 3D Space

title: Inhibition of Return in 3D Space

contributor:
Sun, Hong-jin
Psychology

subject:
inhibition of return
spatial cueing
spatial attention

abstract: This thesis encompasses five chapters. Chapter 1 details the background literature for how the inhibition of return effect manifests in 3D environments. Additional summary is provided about how positioning cues and targets within the boundary of the same objects affects the spread of IOR when compared to when attention is cued in empty space. Finally, the literature review also provides a background for whether the IOR effect is affected by a viewer-centered or world-centered frame of reference. Chapters 2-4 are empirical chapters. Chapter 2 observes a depth-specific IOR effect in a 3D composed of pictorial depth cues. Chapter 3 suggests that this depth-specificity can only occur when cues and targets are positioned in different objects rather than when positioned within a single object. Chapter 4 investigates how the distances between viewer and cue, viewer and target, and cue and target affect the magnitude of IOR, suggesting that the world-centered reference frame influences IOR. Chapter 5 serves as a general discussion and conclusion chapter, discussing the findings and implications of each empirical chapter.

abstract: The distribution of human attention in space can be modulated by spatial and temporal factors. This dissertation studied inhibition of return (IOR), a robust behavioural effect obtained through a spatial cueing paradigm where observers exhibit slower detection times to a target appearing over 300 ms after a cue in a previously cued location. Most research has studied the IOR effect in two-dimensional space; thus, it remains unclear whether, in three-dimensional space (3D) space, slower reaction times occur due to a target appearing in the same world location (defined in 3D coordinates) or in the same retinal location as the cue (i.e., anywhere along an observer’s line of sight to the cue). My thesis examines IOR in a computer-simulated 3D environment, with the location of the cue and target residing in the same versus different depth/distance position either within the same or different object and either relative to the observer or to the world environment. Following a general literature review (Chapter 1), the first empirical chapter (Chapter 2) demonstrates that IOR is depth-specific when the direction of depth switch between cue to target occurs from far-to-near space, suggesting a behavioural advantage for near space in the human attention system. Chapter 3 shows that this depth-specificity and depth-asymmetry of IOR is maintained only when cues and targets are not part of the same object; object membership can therefore override the depth-specific property of IOR in 3D scenes. Chapter 4 introduces motion of the viewpoint, showing that IOR is depth-specific when the cue and target appear in different depth locations in the world environment even when located at the same relative distance from the observer’s viewpoint. Thus, IOR could be the result of an inhibitory tag placed at a location relative to the environment rather than at a location relative to the viewpoint.

abstract: Dissertation

abstract: Doctor of Science  (PhD)

abstract: Human attention can be distributed over space and affected by external events. Prior research using 2D environments has shown that some time after the first stimulus (a cue), the reaction time to a subsequent stimulus (a target) appearing in the same location is typically slower compared to when this target appears elsewhere. Thus, attention likely moves away from a previously observed to more novel location of interest. I examined, in a 3D environment, whether this “location” of reduced attention resides in the same 3D location or retinal location as that of the cue. I also assessed the impact on reaction time for when the cue and target belong to the same or different object and when their locations differ in reference to the observer or world environment. My research suggests that humans maintain a higher level of attention for nearer space when the cue previously appears at a farther location.


title: QUANTIFYING TRUST IN DEEP LEARNING WITH OBJECTIVE EXPLAINABLE AI METHODS FOR ECG CLASSIFICATION

title: EVALUATING TRUST AND EXPLAINABILITY FOR DEEP LEARNING MODELS

contributor:
Doyle, Thomas
Biomedical Engineering

subject: AI, XAI, Trust, Explainability

abstract:
Trustworthiness is a roadblock in mass adoption of artificial intelligence (AI) in medicine. This thesis developed a framework to explore the trustworthiness as it applies to AI in medicine with respect to common stakeholders in medical device development. Within this framework the element of explainability of AI models was explored by evaluating explainable AI (XAI) methods. In current literature a litany of XAI methods are available that provide a variety of insights into the learning and function of AI models. XAI methods provide a human readable output for the AI’s learning process. These XAI methods tend to be bespoke and provide very subjective outputs with varying degrees of quality. Currently, there are no metrics or methods of objectively evaluating XAI outputs against outputs from different types of XAI
methods. This thesis presents a set of constituent elements (similarity, stability and novelty) to explore the concept of explainability and then presents a series of metrics to evaluate those constituent elements. Thus providing a repeatable and testable framework to evaluate XAI methods and their generated explanations. This is accomplished using subject matter expert (SME) annotated ECG signals (time-series
signals) represented as images to AI models and XAI methods. A small subset from all available XAI methods, Vanilla Saliency, SmoothGrad, GradCAM and GradCAM++ were used to generate XAI outputs for a VGG-16 based deep learning classification model. The framework provides insights about XAI method generated explanations for the AI and how closely that learning corresponds to SME decision making. It also objectively evaluates how closely explanations generated by any XAI method resemble outputs from other XAI methods. Lastly, the framework provides insights about possible novel learning done by the deep learning model beyond what was identified by the SMEs in their decision making.

abstract: Thesis

abstract: Master of Applied Science (MASc)

abstract:
The goal of this thesis was to develop a framework of how trustworthiness can be
improved for a variety of stakeholders in the use of AI in medical applications. Trust
was broken down into basic elements (Explainability, Verifiability, Fairness & Ro-
bustness) and ’Explainability’ was further explored. This was done by determining
how explainability (offered by XAI methods) can address the needs (Accuracy, Safety,
and Performance) of stakeholders and how those needs can be evaluated. Methods of
comparison (similarity, stability, and novelty) were developed that allow an objective
evaluation of the explanations from various XAI methods using repeatable metrics
(Jaccard, Hamming, Pearson Correlation, and TF-IDF). Combining the results of
these measurements into the framework of trust, work towards improving AI trust-
worthiness and provides a way to evaluate and compare the utility of explanations.


title: High-Efficiency Power Electronic Converters for EV Fast-Charging Stations with Energy Storage

contributor:
Bauman, Jennifer
Electrical and Computer Engineering

subject: EV fast charging, DCFC, DC/DC Converter

abstract:
Electric vehicle (EV) adoption continues to rise, yet EV sales still represent a small portion of vehicle sales in most countries. An expansion of the DC fast charging (DCFC) network is likely to accelerate this revolution towards sustainable transportation, giving drivers more flexible options for charging on longer trips. However, DCFC presents a large load on the grid which can lead to costly grid reinforcements and high monthly operating costs – adding energy storage to the DCFC station can help mitigate these challenges.
This thesis first performs a comprehensive review of DCFC stations with energy storage, including motivation, architectures, power electronic converters, and detailed simulation analysis for various charging scenarios. The review is closely tied to current state-of-the-art technologies and covers both academic research contributions and real energy storage projects in operation around the world. It is identified that the battery energy storage systems (BESSs) with active front end converter provides high efficiency with reasonable power density in a DCFC station. It is also realized that the isolated DC/DC converter interfacing BESS and EV determines the overall efficiency of a DCFC station with a low grid connection.
Secondly, this thesis analyzes the impact of active front end based DCFC stations connected to a grid distorted with background voltage harmonics. In active front end based DCFC stations, background voltage harmonics produce current not only at the frequencies of the distorted voltage, but also at other coupled frequencies. Various mitigation techniques, such as increasing inner control loop gain, grid voltage feedforward, and selective harmonic compensation, have been adopted in industry to reduce the emissions originating from distorted background voltage. However, although these techniques are effective in suppressing the current at the harmonic orders present in the background voltage, they deteriorate the emission at coupled frequencies. This thesis provides the theoretical explanation of this phenomenon, which is verified by simulation of a two-level active front end in PSCAD/EMTDC. This thesis also discusses the proper treatment of current emission due to background voltage harmonics.
Thirdly, the thesis identifies the semi dual active bridge (semi-DAB) converter as an ideal candidate as the interfacing isolated DC/DC converter between the BESS and the BEV. A novel control strategy is proposed for the semi-DAB converter to achieve wide voltage gain while increasing the efficiency at operational points with high input voltage and low output voltage, which is a commonly occurring scenario when the BESS is fully charged, and the EV battery is at low charge. Furthermore, this thesis also provides an algorithm to determine the required phase-shift in real time for any operating point, eliminating the need to devise the control trajectory offline. A 550 V, 10 kW experimental prototype is built and tested to validate the proposed control strategy. With a 25 A constant charging current, the prototype shows the proposed control strategy can improve efficiency by up to 3.5% compared to the well-known dual phase shift control at operating points with high input voltage (450 – 550 V) and low output voltage (150 – 275 V), with a peak efficiency of 97.6%.
Finally, this thesis proposes a novel variable turns-ratio semi-DAB converter to improve its overall efficiency even further when the input voltage is high and the output voltage is low. Furthermore, a control law is also proposed to determine the turns-ratio, i.e., the operational structure of the converter, which reduces the converter peak and rms current. The 550 V, 10 kW prototype is modified to accommodate the variable turns-ratio high frequency transformer to test the proposed converter and control. The proposed converter with control can further improve the efficiency at many operating points compared to single turns-ratio semi-DAB with DPS control. The peak efficiency achieved is 98.5%.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Low-cost and versatile fabrication of silicon-compatible photonic integrated circuits for active devices and sensors

contributor:
Bradley, Jonathan
Engineering Physics

abstract: The variety of photonic materials required to address the needs of the expanding market and application space for photonic integrated circuits (PICs) is driving the need for widely applicable, reliable, versatile and scalable fabrication techniques. Working with materials that are compatible with Silicon (Si) allows for integration into foundry processing and large-scale integration, which is crucial for economic scaling. However, because Si is a poor emitter of light, this poses a challenge for the implementation of specific components such as monolithic optical amplifiers and lasers, which are needed for the next generation of telecommunication devices and sensors. For this reason, a variety of materials are required to address the growing demand for new functionalities in PICs, including on-chip passive components and optically active amplifiers and lasers. These materials include traditional silicon-compatible materials such as silicon nitride (Si3N4), and less mature materials such as rare-earth doped oxides including aluminium oxide (Al2O3) and tellurium dioxide (TeO2). To process the different materials and fabricate waveguides for a variety of platforms, circuit architectures and applications, it is advantageous to develop robust, versatile, and economic solutions to prepare for a changing and growing industry. This thesis presents a variety of fabrication techniques and protocols to achieve high optical quality materials and waveguides through thin film deposition and patterning, and demonstrates the realization of an optical amplifier and a protein sensor in an erbium-ytterbium co-doped Al2O3 (Al2O3:Er3+:Yb3+) waveguide and a poly(methyl methacrylate) (PMMA)/TeO2-Si distributed Bragg reflector cavity, respectively. The objectives of this thesis are to demonstrate low-loss silicon nitride films using plasma-enhanced chemical vapour deposition (PECVD), to develop a controllable process for waveguide device fabrication using UV writing, to demonstrate optical gain in Er3+:Yb3+:Al2O3 waveguide amplifiers fabricated with wet-etching, and to demonstrate biological sensing on Si chips which are capable of rare-earth integration. Chapter 1 introduces background literature on photonic integrated circuits and provides an overview and comparison of various film deposition and patterning techniques, including those explored in this work. Chapter 2 includes details on the background and theory of waveguides, provides a guide and process to designing waveguides for different mode properties, materials and devices, and introduces the relevant theory for optical amplifiers and photonic biological sensors. Chapter 3 demonstrates a recipe and process for the deposition of silicon nitride films using PECVD at 140 °C and 1.5 mTorr, which shows partially hydrogenated, and non-stoichiometric SiOxNy:Hz films with optical propagation losses as low as 1.3, 0.3 and 1.5 ± 0.1 dB/cm at 638, 980 and 1550 nm respectively, without heat treatment. Chapter 4 presents UV laser writing in negative photoresist as a procedure for prototyping waveguides in Si3N4. Scanning electron microscopy (SEM) was used to analyze feature and gap control, and dry plasma etching was used to realize optical devices such as a directional coupler, Sagnac interferometer, and ring resonator, which demonstrate 50/50 coupling at 1510 nm, 20 dB transmission drop at 1580 nm, and a Q factor of ~13,000 at 1576 nm, respectively. Chapter 5 reports on the deposition and patterning of Al2O3:Er3+:Yb3+ waveguides using reactive co-sputtering and wet chemical etching, with internal net gain of 4.3 ± 0.9 dB at 1533 nm for a 3.0 cm long waveguide when pumped at 970 nm. Chapter 6 presents a hybrid Si-TeO2 Bragg waveguide sensing platform with plasma functionalized PMMA for biological attachment. Thermal, water and protein sensing were performed leading to a sensitivity of 0.13 nm/°C, limit of detection of 5.9 ×10–3 RIU, and a 1.6 nm shift after incubation with 2 μg/mL BSA diluted in PBS with subsequent recovery of the sensor for reuse after stripping. Chapter 7 summarizes the thesis and provides pathways towards optimizing current and future work.

abstract: Thesis

abstract: Doctor of Engineering (DEng)


title: 3-D GEOPHYSICAL MODELLING OF CONFIRMED AND SUSPECTED IMPACT CRATERS IN SOUTHERN ONTARIO, CANADA: CONSTRAINING STRUCTURE ORIGIN, SUBSURFACE GEOLOGY AND POST-IMPACT MODIFICATION

contributor:
Boyce, Joseph I.
Earth Sciences

subject: Hypervelocity impact craters; geophysical surveys, 3-D potential field models, geophysical surveys, digital elevation models, crater subsurface geometry, post-impact modification.

abstract:
Abstract
Impact cratering is a fundamental geomorphic process on planetary surfaces. More than 60% of known hypervelocity impact craters on Earth are either partially or completely buried beneath post-impact sediments and one-third have been discovered with geophysical methods. In this thesis, geophysical surveys (gravity, magnetics, seismic, bathymetric mapping) were conducted at the deeply buried (>400 m) Holleford impact crater (~2.35 km) and two probable impact structures (Charity Shoal, Skeleton Lake) in southern Ontario, Canada. 3-D potential field models were constructed to determine the subsurface geology and buried crater morphology, and to evaluate evidence for possible impact versus endogenic origins.
Holleford Crater is a deeply buried, Late Proterozoic-Early Cambrian (ca. 550 ±100 Ma) simple impact crater (~2.4 km) in southeastern Ontario, Canada. Land-based magnetic and gravity surveys and modelling were conducted in this study, recorded a ~ -3 mGal Bouguer anomaly and small (~30 nT) magnetic anomaly over the crater basin.  3-D gravity modelling revealed a deeply buried simple impact basin in Mesoproterozoic basement with an estimated rim-to-rim diameter (D) of 1.8-2 km, a residual rim height of ~20-30 m and true depth (dt) >400 m. The southeast crater rim is dissected by a 150 m deep, 400 m wide erosional channel produced by fluvial rim dissection. The outflow is infilled by >50 m of Late Cambrian clastic sediments, indicating a probable Late Proterozoic to Early Paleozoic impact event.
Charity Shoal is a 1.2-km-diameter, 20 m deep, circular bedrock shoal in eastern Lake Ontario. Marine seismic profiling and total field magnetic surveys (140-line km) were conducted over a 9-km2 area and combined with available multi-beam bathymetric data to evaluate the subsurface geology and structure origin. Seismic surveys revealed ~30 m of Quaternary sediments overlying Middle Ordovician (Trenton Group) carbonates in the central basin and evidence for folding and faulting of the structure rim. Magnetic surveys recorded an annular magnetic high (> 600 nT) and a central magnetic low (~500-600 nT) coincident with a ~-1.7 mGal Bouguer gravity anomaly. The continuity of Middle Ordovician bedrock below the structure rules out a post-Paleozoic intrusion and a pre-Paleozoic intrusion is ruled out with the gravity anomaly. A deeply-buried (> 450 m) impact crater is the only scenario consistent with geophysical evidence.  The crater has a rim-to-rim diameter of ~1.2 km, and rim height of ~15-20 m. A 100-m wide breach in the southwestern rim records a possible outflow channel.

Skeleton Lake is a suspected (~4.0 km) Paleozoic-age impact structure in Muskoka, Ontario. The lakebed morphology, subsurface structure and possible impact origin were investigated with high-resolution geophysical surveys (magnetics, bathymetry; ~140 line-km) and 3-D magnetic modelling.  Bathymetric data reveal a deep (>65 m) central basin with arcuate (Paleozoic?) bedrock ridges that rise >30 m above the southwestern lakebed. Magnetic surveys recorded a >700 nT magnetic low, which truncates northwest-southeast regional magnetic trends. Low-amplitude, northwest-trending magnetic lineaments delineate basement shear zones below the basin centre. Through-going magnetic lineaments and lack of thermal alteration (e.g., dikes, fenitization) in Mesoproterozoic rocks indicate a volcanic origin is unlikely. A 1.2 km diameter volcanic plug with an Early Cambrian remanence (D = 82.2°, I = 82.7°) can reproduce some aspects of the magnetic anomaly but is at odds with the Bouguer gravity anomaly (~ -3 mGal). Forward modelling of a crater-form basin with induction and remanence magnetization yielded an estimated structure depth of ~1200 m. The basement surface model shows a complex basement topography with no apparent rim structure and elevated ‘pinnacles’ that may represent eroded remnants of a central uplift or a highly-dissected basement topography. The structure apparent diameter (> 4.2 km) and complex basement topography suggest a heavily-modified transitional crater, similar with the Gow (Saskatchewan, Canada) and Kärdla (Estonia) impact structures.

  This thesis demonstrates the subsurface exploration of confirmed and suspected impact structures, integrating seismic, potential field (magnetics, gravity) and digital elevation data within a 3-D geophysical modelling workflow. The approach provides important new insights into the surface and subsurface geology, morphology, and post-emplacement modification of the Holleford impact crater, and new geophysical constraints for evaluating two suspected impact structures. Geophysical data confirm that Charity Shoal and Skeleton Lake are deep-seated, crater-form depressions in Mesoproterozoic basement rocks. The weight of geophysical and geological evidence points to impact cratering processes as opposed to an endogenic (volcanic) origin for both structures.

abstract: Thesis

abstract: Doctor of Science  (PhD)


title: Characterizing Associations Between Trauma and Substance Use and Related Problems Among Samples with Differing Clinical Presentation & Severity

title: TRAUMA AND SUBSTANCE USE AMONG DIFFERING SAMPLES

contributor:
McKinnon, Margaret
Neuroscience

subject:
trauma
substance use
posttraumatic stress disorder
substance use disorder
dissociation
emotion dysregulation
alcohol use
cannabis use

abstract:
Posttraumatic stress disorder (PTSD) and substance use disorder (SUD) frequently co-occur. Comorbid PTSD+SUD confers heightened risk of other mental health concerns, suicidality, mortality, and functional impairment. Current treatments for comorbid PTSD+SUD show inconsistent results, highlighting the need for a more comprehensive understanding of the associations between PTSD and SUD symptoms. The current dissertation aimed to characterize the associations between PTSD and SUD using structural equation modelling among three different samples with differing clinical severity and presentation: (1) concurrent disorders sample with a high prevalence of PTSD; (2) an in-patient sample seeking treatment for PTSD; and (3) a subclinical sample of healthcare workers and public safety personnel. Data were extracted from multiple clinical databases across different studies to evaluate the associations between PTSD symptoms and alcohol/cannabis/substance use-related problems. Furthermore, the role of underlying mechanisms such as dissociation and emotion dysregulation, which are associated with both PTSD and SUD, were analyzed. All analyses used a structural equation modelling framework to represent the complex clinical presentation of comorbid PTSD+SUD analytically. A relatively consistent pattern of results was observed across the three samples. Global PTSD symptoms were significantly associated with cannabis-related problems, alcohol-related problems, and other illicit substance-related problems. Among PTSD symptoms, the reactivity symptom cluster (characterized by symptoms of hypervigilance, irritability, reckless behaviour, problems with concentration and sleep disturbances) was significantly associated with alcohol/cannabis/substance-related
v
problems across among the three samples. Furthermore, underlying mechanisms such as dissociation and emotion dysregulation significantly mediated the relations between PTSD symptoms and alcohol/cannabis/substance-related problems. Overall, the current results contribute to the limited literature examining the associations between PTSD and SUD symptoms. Lastly, the current results have important clinical implications for identifying efficacious treatment targets for comorbid PTSD+SUD.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)

abstract: Psychological distress following a traumatic event, known as traumatic stress, is often associated with problematic alcohol and/or substance use. The co-occurrence of these two confers a heightened risk of other mental health problems. As such, studying how these phenomena are associated with one another and what about each thing is more important to the association is important to understand. The purpose was to examine the connection between these phenomena among three different groups of people: two treatment-seeking groups and non-treatment seeking group one group. Traumatic stress was associated with problematic substance use in all three groups. In addition, other factors like mentally escaping from your body and having difficulties with regulating your emotions explained how traumatic stress and problematic substance use were connected to each other. These findings can help clinicians hone their treatment programs to better help individuals struggling with traumatic stress and problematic substance use.


title: Comprehensive Mapping of Bacterial Metabolism Guides Inquiry Into Specialized Metabolites

contributor:
Magarvey, Nathan
Biochemistry and Biomedical Sciences

abstract:
Bacterial specialized metabolites (SMs) have long interested scientists due to their diverse chemistries which can harbour antimicrobial activity. The discovery of these molecules experienced a period of exponential success in the mid-1900s and today is guided by next-generation sequencing and liquid chromatograph-mass spectrometry technology. Despite these technological advances, however, they remain under-leveraged. Now, merging disease and antibiotic resistance threaten the security provided by existing antimicrobial medicines. There is an urgent need for a more targeted approach in the discovery of novel SMs, which leverages the tremendous efforts of the past alongside modern big data analytics.
To this end, I set out to develop a foundation that could guide SM discovery in the future. I began by bridging all available bacterial metabolism data into a common latent space. Using known metabolic pathways, I generated a library of biosynthetic units used in a novel program to encode metabolites. Each unit was connected to its requisite genes, which were leveraged to reverse engineer this platform by predicting the chemical structures of SMs directly from their encoding genes. Finally, deep learning models were used to annotate some of these chemical-genomic connections as being associated with a particular activity, in this case siderophore activity.
This suite of software tools offers promising opportunities to pursue downstream applications, including the connection of unknown genes to metabolites and the identification of novel chemical-genomic connections. In order for these prospects to be realized, however, this intricately-connected network of data necessitates more sophisticated interpretation. Indeed, interconnected chemical, genomic and activity data lends itself particularly well to analysis by graph neural networks. The foundational work described in this communication builds the basis for this comprehensive analysis, which may uncover new insights into the bacterial metabolism we thought we knew.

abstract: Thesis

abstract: Master of Science (MSc)


title: Distal Radius Fracture and Family Role Responsibilities: Patients’ Perceptions of Their Partners’ Contributions to Family Role Responsibilities During the Early Recovery

contributor:
MacDermid, Joy
Rehabilitation Science

abstract:
Background: Distal radius fracture is a prevalent upper extremity injury. Exploring partners’ role in providing support from the patients’ perspective may influence the experience of recovery following this injury. Moreover, describing coping strategies applied by patients and their partners to complete their family role responsibilities can promote recovery outcomes.
Objectives: The objective of this research is to explore: the lived experiences of patients with distal radius fracture and their perspective on their partners’ contribution to completing family role responsibilities during their recovery; implemented coping strategies, and analyze their perspectives through a sex and gender lens.
Methods: A Semi-structured interview was conducted with persons in the acute recovery stage following a distal radius fracture who had partners. We recorded, transcribed, coded, and thematically analyzed twelve interviews. A process of constant comparison was applied until data saturation occurred. Trustworthiness techniques were used in data analysis and included peer reviews.
Results: The interviews with twelve persons with distal radius fracture reflected six themes. Four themes emerged with respect to the partners’ contribution to providing support for patients in 1) the emergency time after the fracture; 2) physical family chores; 3) social and recreational activities, and 4) emotional support. The fifth theme described that person with DRF valued diverse support; informational support from health professionals was demanding and necessary from the person’s perspective. The sixth theme informed different coping strategies applied to minimize the physical and emotional burdens of the fracture. The impact of gender on the pattern of seeking/receiving social support was discussed as the secondary purpose of this study; women required instrumental and emotional support while the emotional status of men did not affect by distal radius fracture. However, this finding of gender differences is required more future investigation.
Conclusion: Multiple social support provided by partners to persons with a distal radius fracture to complete family roles were highlighted through patients’ perspectives. Also, implemented coping strategies within families were explored. However, partners’ perspectives and experiences are required to promote our knowledge of patients’ and their partners’ needs to complete family roles during the early recovery.

abstract: Thesis

abstract: Master of Health Sciences (MSc)

abstract:
Distal radius fracture is a common wrist injury, causing pain, movement restriction, difficulties with daily living activities, and frustration. This injury often happens in women after menopause because their bones have become weaker. Some people will need to have surgery for a distal radius fracture, but many will need to wear a cast instead. To regain wrist function and muscle strength, people should do therapy after their fracture. But just doing exercises is not enough: it is very important to think about how they will manage everyday life activities and get the help they need while they recover.
	The goal of this dissertation is to discover partners’ roles to provide help for patients in family role responsibilities after a distal radius fracture. We also found different strategies may be used to reduce hardships during the first two weeks of recovery. Finally, there were differences between men and women to receive/seek help from their partners. Women required physical and emotional support while men did not seek strong emotional support.


title: DEVELOPING A CLINCALLY RELEVANT ISOGENIC CELL LINE OF HUNTINGTON’S DISEASE

contributor:
Truant, Ray
Biochemistry and Biomedical Sciences

abstract: Huntington’s Disease (HD) is a neurodegenerative disease caused by a CAG expansion in exon 1 of the HTT gene. The age of symptom onset is inversely correlated with the length of the CAG tract. CAA interruptions in the CAG tract have a protective effect, delaying the onset of symptoms despite still coding for a glutamine residue. Evidence suggests that genes outside of the CAG expansion also contribute to differences in age of symptom onset. To improve our knowledge of disease, a clinically relevant model system is necessary. Here, we identify that many model systems use overexpressed protein that fails to adhere to the stoichiometry of an endogenous system. Many systems also use CAG expansions beyond what would be seen in a clinical case of HD or do not appropriately account for the influence of other genes. TruHD fibroblast cells immortalized with human telomerase reverse transcriptase are derived from patient samples and have a stable genome. Here, we discuss attempts to develop isogenic cell lines by editing TruHD cells to have different CAG repeats. While we were unsuccessful in isolating clones carrying the desired edit, future researchers can use this work as a guide to navigate the successful creation of isogenic cells. We can compare phenotypes between pre and post edited cells to see how they change with a new CAG length in an otherwise stable genetic background. We also discuss the successful editing of TruHD cells with a CAG to CAA base edit to introduce a CAA interruption in diseased cells. We discuss how to propagate these cells for future research to compare pre and post edited cells to better understand the protective action of CAA interruptions.

abstract: Thesis

abstract: Bachelor of Science (BSc)

abstract: Huntington’s Disease is a neurodegenerative disease caused by excessive CAG repeats in the HTT gene. Without a way of delaying or stopping symptoms, we need model systems to understand why some individuals develop disease later than others. We know that people develop symptoms earlier in life when they have more CAG repeats, but we don’t fully understand the contribution of their other genes. We explore this by attempting to edit the DNA of a clinically relevant cell line to change the CAG repeats. Once we establish this system, we can compare the cells before and after editing to see exactly what changes are caused by the CAG repeat length. While we were not able to develop the cell line, this work should be used by future researchers as a troubleshooting guide as they develop a representative model system.


title:
THE PRACTICE OF MANAGING CHRONIC COUGH
THE MANAGEMENT OF CHRONIC COUGH

contributor:
Brooks, Dina
Rehabilitation Science

abstract: This thesis focuses on chronic cough topics, in both the general population and those with chronic respiratory diseases. Study one consists of a systematic review in which the primary aim was to summarize the effect of non-pharmacological therapies on cough-specific quality of life in individuals with and without chronic respiratory diseases. For study two, we conducted a nationwide survey study, which was administered to healthcare providers working in pulmonary rehabilitation (PR) facilities. Given that education was a common component in non-pharmacological interventions, seen in study one, the overall goal of study two was to determine whether chronic cough is assessed and/or managed within PR, as education is also a foundational pillar in PR. The implications of this work seek to inform healthcare providers of alternative chronic cough management therapies, by bringing awareness to the importance of conducting formal cough assessment and management in PR.

abstract: Thesis

abstract: Master of Science Rehabilitation Science (MSc)


title: Active and Reactive Ultrafiltration Membranes for Water Treatment

contributor:
de Lannoy, Charles-François
Chemical Engineering

subject:
Membrane technology
Electrochemistry
Catalysis

abstract: Climate change, industrial and agricultural activities, and population growth exacerbate global water stress. A variety of advanced technologies have been studied to alleviate water scarcity and water pollution. Membrane technology owing to its low footprints and ease of operation, has drawn intensive attention for water purification and wastewater treatment. Further, integrating membrane technology, electrochemistry and catalysis can improve separation and selectivity of the filtration process. This work aims to fabricate high-performance active and reactive ultrafiltration membranes involving electrically conductive membranes, catalytic membranes and electrocatalytic membranes. Their use in water treatment inspires the development of advanced functionalized membranes and further accelerates the transition to industrial applications.

abstract: Thesis

abstract: Doctor of Engineering (DEng)


title: Access to Sexual and Reproductive Health Services: Barriers Faced by Women Living in Slums in North India, A Scoping Review

contributor:
DiLiberto, Deborah
Global Health

subject: Sexual and Reproductive Health, Family planning, Contraceptives, Reproductive empowerment, Reproductive agency, North India, Slums, Scoping Review

abstract:
Background: A significant amount of research has previously been conducted in developing countries such as India, to improve women’s sexual and reproductive health. However, women living in North Indian slums still have poor access to proper sexual and reproductive healthcare. The aim of this thesis is to investigate the published literature to create a consolidated understanding of the key barriers faced by women in slum populations when accessing sexual and reproductive health services in Northern India.
Methods: A scoping review was carried out following the five stages outlined in Arksey and O’Malley’s framework. Five online databases (MEDLINE, Global Health, Ovid Emcare, Embase, and Web of Science) were searched. An interpretive thematic analysis was conducted to extract meaningful themes from the data using the Conceptual Framework for Reproductive Empowerment developed by the International Center for Research on Women
Results: In total, 28 articles were identified to be incorporated into the scoping review. The results of this study were grouped according to the CFFRE to understand how they compared in regard to women’s reproductive empowerment. This scoping review found reproductive empowerment was significantly hindered by women lacking a proper education and understanding of SRH services, lack of employment and financial resources. Additionally, women’s husbands and mothers-in-laws were barriers to contraceptive use. Finally, poor interactions with healthcare providers and the healthcare system, and systemic factors such as behaviours in treatment seeking, son preference and religion were barriers to accessing SRH services.
Conclusion: This scoping review investigated the barriers faced by women living in slum populations in Northern India to accessing SRH services. The results of this study contribute to the literature by identifying areas that require improvement to SRH services for women living in slums, and will be integral to implementing strategies and interventions to allow better access to SRH services in the future.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: A significant amount of research has previously been conducted in India, to improve women’s sexual and reproductive health. However, women living in North Indian slums still have poor access to proper sexual and reproductive healthcare. Therefore, this study investigated the key barriers faced by women in slum populations when accessing sexual and reproductive health services in Northern India. A review of previous studies was conducted by searching five electronic databases and a total 28 articles were included into the review. This study found that women lacking a proper education and understanding of SRH services, lack of employment and financial resources, and women’s husbands and mothers-in-laws were barriers to SRH services. Finally, poor interactions with healthcare providers and the healthcare system, and systemic factors such as behaviours in treatment seeking, son preference, and religion were also barriers to accessing SRH services.


title: Enforcing Temporal and Ontological Dependencies Over Graphs

contributor:
Chiang, Fei
Computing and Software

subject:
Graphs
Temporal graphs
Keys
Dependencies
Temporal dependencies
Graph dependencies
Data cleaning

abstract:
Graphs provide powerful abstractions, and are widely used in different areas. There has been an increasing demand in using the graph data model to represent data in many applications such as network management, web page analysis, knowledge graphs, social networks. These graphs are usually dynamic and represent the time evolving relationships between entities. Enforcing and maintaining data quality in graphs is a critical task for decision making, operational efficiency and accurate data analysis as recent studies have shown that data scientists spend 60-80% of their time cleaning and organizing data [2]. This effort motivates the need for effective data cleaning tools to reduce the user burden. The study of data quality management focuses along a set of dimensions, including data consistency, data deduplication, information completeness, data currency, and data accuracy. Achieving all these data characteristics is often not possible in practice due to personnel costs, and for performance reasons. In this thesis, we focus on tackling three problems in two data quality dimensions: data consistency and data deduplication.
To address the problem of data consistency over temporal graphs, we present a new class of data dependencies called Temporal Graph Functional Dependency (TGFDs). TGFDs generalize functional dependencies to temporal graphs as a sequence of graph snapshots that are induced by time intervals, and enforce both topological constraints and attribute value dependencies that must be satisfied by these snapshots. We establish the complexity results for the satisfiability and implication problems of TGFDs. We propose a sound and complete axiomatization system for TGFDs. We also present efficient parallel algorithms to detect inconsistencies in temporal graphs as violations of TGFDs. To address the data deduplication problem, we first address the problem of key discovery for graphs. Keys for graphs use topology and value constraints to uniquely identify entities in a graph database and keys are the main tools for data deduplication in graphs. We present two properties that define a key, including minimality and support and an algorithm to mine keys over graphs via frequent subgraph expansion. However, existing key constraints identify entities by enforcing label equality on node types. These constraints can be too restrictive to characterize structures and node labels that are syntactically different but semantically equivalent. Lastly, we propose a new class of key constraints, Ontological Graph Keys (OGKs) that extend conventional graph keys by ontological subgraph matching between entity labels and an external ontology. We study the entity matching problem with OGKs. We develop efficient algorithms to perform entity matching based on a Chase procedure. The proposed dependencies and algorithms in this thesis improve consistency detection in temporal graphs, automate the discovery of keys in graphs, and enrich the semantic expressiveness of graph keys.

abstract: Dissertation

abstract: Doctor of Science  (PhD)


title: Type VIIb secretion system effector export and neutralization

title: Mechanistic insights into type VIIb secretion system effector export and neutralization

contributor:
Whitney, John
Biochemistry and Biomedical Sciences

subject:
type VII secretion
bacterial protein secretion
interbacterial competition
protein structure

abstract: The type VII secretion system is a protein export pathway linked to diverse phenotypes in both Actinobacteria and Firmicutes. The Actinobacterial subtype of the T7SS, referred to as T7SSa, has been shown to play a critical role in various aspects of Mycobacterial life including virulence, conjugation, and metal homeostasis. The T7SSb of Firmicutes bacteria on the other hand has similarly been shown to influence virulence but by the direct growth inhibition of competitor bacteria. Structure-function analyses of the T7SSa apparatus as well as various effectors and chaperones have begun to build a more mechanistic understanding of how T7SSa functions. In contrast, we know little of how the T7SSb functions despite its noted importance to both pathogens and environmental bacteria such as Bacillus, Staphylococcus, Enterococcus, and Streptococcus. During my thesis work, I have addressed several gaps in our understanding of T7SSb function. The three major questions that I have studied are: (1) how do T7SSb immunity proteins inhibit the toxicity of their cognate toxins, (2) how does the T7SSb export effectors through the thick Gram-positive cell wall, and (3) what is the role of chaperone proteins in facilitating T7SSb effector export?

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Bacteria require space and various nutrients to survive and grow and must therefore compete against other bacteria for access to these resources. To gain advantage over their competitors, many bacteria have developed molecular weapons that target and kill other closely related bacteria. Some of these weapons take the form of protein secretion machines that export antibacterial toxins. Gram-positive bacteria use the type VIIb secretion system (T7SSb) to inhibit the growth of other Gram-positive bacteria. In this work, I explore several aspects of T7SSb including: (1) how toxins are inhibited by immunity proteins, (2) how toxins are secreted through the cell envelope, and (3) how toxins are recognized by the secretion apparatus. The goal of this work is to better understand how T7SSb functions at the molecular level.


title: Protecting Diamond Indenters for Nanoindentation Between 400-750°C Using Titanium

contributor: Mechanical and Manufacturing Engineering

subject:
Diamond
Coating
Nanoindentation
Indenter
Diamond Coating

abstract:
The 400°C limitation to the most common nanoindenter material, diamond, is not due to diamond  changing to graphite in air, which can happen above 750°C, but to the reaction of the nanoindenter with the sample, causing a change in the geometry.  The nanoindentation methodology is very sensitive to a change in nanoindenter geometry, thus the typical solution for measurements above 400°C is to use a cBN nanoindenter.  However, the cBN indenter that is commercially used at temperatures above 400°C is too soft for measuring hard coatings such as machine tool coatings.  There is limited published research on improving nanoindentation measurements in this way.  Thus, the objective of this thesis is to address whether a coated diamond could be used for nanoindentation between 400-750°C.
Due to the results of early experiments PVD titanium is the focus of this thesis as it will adhere to diamond by forming a carbide interlayer, TiC.  A methodology to determine the best coating based on resistance to oxidation and robustness of the coating at temperature was used, allowing the exploration of several different titanium based alloys and coating thickness.  The methodology used is as follows:
1. PVD coatings of titanium and titanium based alloys TiAl, TiN, and TiAlN were oxidized at 500, 575, and 650°C.  Measurements by SEM and EDS were taken after the oxidation at each temperature.  Of the coatings tested, the pure titanium coating was determined to be the best coating.
2. The coating thickness of 0.25, 0.50, and 1.0 um were evaluated with the same static oxidation test applied to the different alloys.  It was determined that 0.50 um was the best thickness.  A duplicate 0.50 um thick sample had a cross-section machined by FIB, and was examined by STEM, HAADF and EELS.  The results confirmed that TiC was being formed at the expected rate.
3. To determine whether a coated nanoindenter could be used for measurements, a nanoindenter was first calibrated, coated by PVD with 0.50 um thick titanium, and calibrated again.  The results confirmed that a coated nanoindenter could be used for performing nanoindentation measurements.
4. To determine whether the titanium PVD coating would adhere to the diamond at temperature, a coated nanoindenter was used to measure fused silicon at 450°C.  After each measurement, the nanoindenter was examined by SEM and EDS.  The results confirmed that the titanium coating adhered to the diamond.
This thesis demonstrates that a titanium PVD coating can protect a diamond nanoindenter during measurements between 400-750°C.  The primary contributions are that coated diamond nanoindenters can be used for nanoindentation measurements, and that titanium PVD coated nanoindenters can be used for nanoindentation measurements between 400-750°C.  Additional contributions include the testing of adhesion of titanium PVD coating to diamond between 400-750°C, and a methodology of evaluating coatings.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Adjuvanted Influenza Vaccination in Children

contributor:
Loeb, Mark
Health Research Methodology

abstract:
Children are at high risk for influenza-related morbidity, including severe complications of illness and hospitalizations. Seasonal influenza vaccination is recommended as the primary method of prevention and protection. Vaccine efficacy has been shown to vary based on host demographics, immune history, influenza type and subtype, and seasonal match of the vaccine antigens to the circulating influenza strains. Adjuvanted vaccination has been shown to induce greater breadth, magnitude and longevity of antibody responses. Research characterizing correlations between host factors, vaccine formulation, antibody responses and influenza outcomes would provide insight on how these relationships contribute to adjuvant-mediated vaccine effectiveness in children.

In this thesis, I explored whether adjuvanted vaccination was associated with attenuated symptom severity in breakthrough influenza infections, as compared with non-adjuvanted vaccinees. I then explored the utility of vaccine reactions as predictors of post-vaccination antibody responses, accounting for the effect modification of the adjuvant. Finally, I used a causal mediation analysis to estimate the proportion of relative protection in adjuvanted vaccinees which is attributable to the increased antibody responses in this group.

We found that adjuvanted vaccination was associated with significant reductions in fever and systemic symptom severity in breakthrough influenza A infections. We observed that total, systemic and respiratory reactogenicity significantly interacted with adjuvanted vaccination, leading to enhanced antibody responses relative to non-adjuvanted vaccinees. Finally, we found that adjuvanted vaccine protection was not significantly mediated by the increased antibody titers in this group.

Our findings provide insight on determinants of adjuvanted vaccine effectiveness in children. Our work may inform future research examining the adjuvant moderation of innate and adaptive immunity in children, which may help define new correlates of protection against influenza. Greater understanding of the network of these relationships and their causal contribution to vaccine protection would contribute to the fields of immunology, vaccinology, and epidemiology.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Children are at high risk of complications related to influenza infections, and are recommended to receive seasonal vaccination. Identifying host and vaccine characteristics which are associated with protection against influenza in children would be valuable for the development of improved vaccines. Adjuvanted influenza vaccines have been assessed in clinical trials but are not yet licensed for children. In this thesis, we evaluate relationships between vaccine formulations, reactions, the magnitude of post-vaccination antibody responses, protection against influenza and presentation of symptoms in breakthrough infections. We aim to further explore these relationships by estimating the proportion of relative adjuvanted protection which is mediated by increased antibody responses to this vaccine. We explore the relationships between vaccine formulation and host factors, and test the associations between these relationships and adjuvanted vaccine efficacy and effectiveness in children.


title: DEVELOPMENT OF METHODOLOGIES TO ASSESS AUTONOMIC NERVOUS SYSTEM FUNCTIONING AND NEUROMODULATION FOR THE DIAGNOSIS AND TREATMENT OF COLONIC MOTILITY DISORDERS

title: AUTONOMIC ASSESSMENT FOR GI DYSMOTILITY AND NEUROMODULATION

contributor:
Huizinga, Jan
Biomedical Engineering

subject:
Autonomic, Neuromodulation, Motility
Parasympathetic, Sympathetic

abstract: Although parasympathetic activity (PNS) is the primary driver and sympathetic activity (SNS) is a significant inhibitor of colonic propulsive activity, they are rarely measured, and hence, they almost play no role in diagnosing dysfunction or standard treatments for chronic conditions such as refractory constipation. We aimed to develop methodologies for the assessment of autonomic nervous system (ANS) activity, establish criteria for autonomic dysfunction, and study if stimulation of lumbar and sacral autonomic nerves using low-level laser therapy (LLLT) could affect the ANS and explore it as a potential treatment of autonomic dysfunction to restore colonic motility. By studying the active standing test and the table tilt test as a method to evoke activity in the ANS, we rejected LF power, SD1 and SD2 of Poincare plot, Pre-ejection-period (PEP), complex-correlation-measure (CCM) and detrended fluctuation analysis (DFA). Respiratory-Sinus-Arrhythmia (RSA), Root-Mean-Square-of-Successive-Differences (RMSSD) were selected for PNS activity, the Baevsky’s-Stress-Index (SI) was chosen for SNS activity, and SI/RSA and SI/RMSSD were introduced as a measure of autonomic balance. We explored high-resolution-colonic-manometry with concurrent electrocardiography to observe whether these parameters could be associated with ANS changes during colonic motor patterns. High-amplitude-propagating-pressure-waves were associated with a strong parasympathetic activity and decreased sympathetic activity. Comparing ANS reactivity of patients with severe motility disorders to controls in response to postural changes, we observed that most patients have low PNS and elevated SNS baseline activity and reactivity. This established a way to evaluate autonomic dysfunction in patients with colon motor disorders. A single session of LLLT using LED and laser light on the lumbar and sacral spine in 41 patients with chronic gastrointestinal motor dysfunction indicated that treatments with LED light followed by laser light significantly increased parasympathetic activity and decreased sympathetic nervous system activities. These results initiated a study into the effects of LLLT on restoring autonomic dysfunction in chronic refractory colonic motility disorders.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: A Reduced Switch-Count Power Cell Configuration for Medium Voltage Cascaded Cell Motor Drives

contributor:
Narimani, Mehdi
Electrical and Computer Engineering

abstract:
Multilevel inverters (MLI) are the foundation of motor drives in medium and high-voltage applications, allowing low voltage devices in high power applications. The Cascaded H-Bridge (CHB) is a multilevel inverter with significant popularity and unique advantages due to its modular structure. The modularity of the CHB allows a scalable design that accommodates various power ratings with minimal changes. In a typical CHB, a six-pulse diode rectifier and an H-Bridge inverter provide power from the grid to the load. As a diode rectifier only allow unidirectional power flow, the typical CHB is confined to only receiving power from the grid. The unidirectional nature of the typical CHB can propose energy loss if used in regenerative applications. A regenerative CHB with two-level voltage source inverters rather than diode rectifiers has been introduced to address the unidirectional power flow. However, this solution proposes a significant increase in the system's complexity, cost, and size. As the demand for efficient energy increases, the research on more suitable-sized and economical regenerative CHBs has gained substantial attention.
In this thesis work, two new reduced switch-count regenerative CHB power cells are proposed. Both proposed power cells reduce the number of switches per cell by four. The challenges that arise are addressed by introducing new control and carrier phase-shifting techniques. The switch-count reduction aims to reduce the complexity, cost, and size of the conventional regenerative CHB.
The theoretical analysis and simulation studies demonstrate the potential of the new reduced switch-count regenerative power cells and its capability to replace the conventional regenerative CHB power cell.
Experimental validation of one of the proposed power cells is conducted with a single-cell configuration. The experimental result for conventional regenerative, three-phase reduced switch-count and the new proposed power cells are presented to compare their operation. The future work of this thesis includes experimental validation of the new proposed power cell in a 7-level regenerative CHB drive and operation of the system with a regenerative motor load.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: THE EFFECTS OF HOUSEHOLD AIR POLLUTION ON CHILDHOOD ASTHMA, ACUTE LOWER RESPIRATORY TRACT INFECTION AND LUNG FUNCTION

contributor:
Kurmi, Om
Global Health

subject:
Household Air Pollution
Asthma
ALRI
Lung Function
Acute Lower Respiratory Infection

abstract:
Introduction and Rationale: Household Air Pollution (HAP) refers to the pollution of air in the indoor environment, from the combustion of solid fuels such as biomass and coal. The World Health Organization (WHO) estimates that 2.6 billion people today are exposed to HAP daily. Women and children tend to be at a higher risk of exposure due to their increased time spent indoors. This can result in a range of adverse cardio-respiratory outcomes such as asthma, Acute Lower Respiratory Infection (ALRI) and Chronic Obstructive Pulmonary Disease (COPD). This thesis document investigates the association between HAP and the adverse respiratory outcomes, namely lung function, ALRI and asthma in children.
Methodology: Systematic Reviews were conducted to synthesize the effect of HAP on lung function, ALRI, and asthma. The lung function outcome was synthesized in a narrative manner, while the pooled estimates for the ALRI and asthma outcomes were synthesized by meta-analysis.
Results: Exposure to HAP is associated with decreased lung function growth, and an increased risk of the incidence of ALRI in children. No association was noted between HAP exposure and the incidence of asthma in children.
Conclusion: The effect of HAP on childhood growth of lung function and the incidence of ALRI provides evidence justifying the universal transition to cleaner fuels and technologies, such as electricity and natural gas.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: Household Air Pollution (HAP) refers to the pollution of indoor air caused by the combustion of solid fuels, such as biomass, for the purposes of heating and cooking. According to the World Health Organization (WHO), 2.6 billion people are exposed to HAP daily. Women and children are especially at high risk of exposure, due to the time spent indoors. This places them at a higher risk of adverse respiratory outcomes, such as Acute Lower Respiratory Tract Infection (ALRI), asthma, Chronic Obstructive Pulmonary Disease (COPD) and reduced lung function. This thesis document investigates the association between HAP and the adverse respiratory outcomes, namely lung function, ALRI and asthma in children. It was found that HAP is associated with a decrease in childhood lung function growth, and an increased risk of the incidence of ALRI. However, there was no clear association between the incidence of asthma and HAP.  The results of the systematic reviews justify a transition from the use of solid fuels to clean fuels and technologies.


title: Discovery of Temporal Graph Functional Dependencies

abstract: Real-world graphs are dynamic and evolve over time. Data quality in evolving graphs is essential to downstream decision making and fact checking. This work studies the discovery of Temporal Graph Functional Dependencies (TGFDs), a recently defined class of data quality rules for enforcing consistency over evolving graphs. TGFDs impose topological and attribute dependency constraints over a period of time. We define minimality and support for TGFDs and formalize the TGFD discovery problem. Defining TGFDs manually is a laborious task and requires domain expertise. Hence, we introduce TGFDMiner, a sequential algorithm that discovers minimal and frequent TGFDs. We define various optimizations for TGFDMiner that improve runtime.

abstract: Thesis

abstract: Master of Science (MSc)


title: EVALUATION OF INTERLOCKING CONCRETE BLOCK PAVEMENT WITH RECYCLED MATERIALS BASED ON EXPERIMENTAL AND FINITE ELEMENT ANALYSIS

contributor:
Tighe, Susan
Civil Engineering

subject:
Interlocking Concrete Block Pavement
Finite Element Analysis
Recycled Materials

abstract:
To address the challenges associated with urban expansion and environmental changes, innovative interlocking concrete block pavement (ICBP) is being researched for usage in urban areas. The ICBP is designed to have higher durability and better long-term performance compared to traditional asphalt pavement. Using recycled concrete aggregates (RCA) and supplementary cementing materials (SCMs) can provide many environmental benefits. The objective of this research is to investigate the mechanical properties of concrete with recycled materials. This also involves the assessment of deflection and stresses associated with ICBP using the finite element method.
Four concrete mixtures with different RCA and SCMs contents were designed and cast. The RCA replacement levels were 20% and 40%, while slag and glass pozzolan were added to improve mechanical properties. The results showed that the use of RCA had adverse impacts on workability. The 28 days compressive strength of the Control Mix was 40 MPa. The compressive strength of Mix 3 was 40.5 MPa which was the highest strength among all mixtures. It demonstrated that a 40% RCA replacement level could have a non-negative effect on mechanical properties when the SCMs are added.
A three-dimensional pavement model was established using ABAQUS software. The orthogonal experimental design was used to evaluate the effects of the length/width ratio of blocks, the block thickness, the elastic modulus, and the laying pattern of blocks on the deflection and von Mises stress of all ICBP models under the vertical load. Considering the deflection of the loading area, the length/width ratio had the greatest effect, then comes with thickness, elastic modulus, and laying pattern according to the Range Analysis. The bigger block size and higher elastic modulus of blocks could provide even better performance. Overall, the herringbone laying pattern is recommended as the optimum laying pattern with minimum deflection. It also contributes to better load spreading.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Simultaneous testing of multiple subjects in ecologically valid assessments of hearing aids and assistive listening for speech in noise and music

contributor:
Bruce, Ian
Electrical and Computer Engineering

subject:
listening effort
hearing aids
music
testing

abstract:
Listening effort, or the amount of cognitive effort required to listen to a sound of
interest, is an important measure of hearing performance, especially for hearing aid
users. Hearing loss leads to increased listening effort in noisy situations and ideally
hearing aid processing would reduce this effort. The goal of the two listening effort
studies were to collect multiple measures of listening effort in an ecologically valid
scenario, testing the effects of background noise, reverberation, and hearing aid directional
processing on listening effort and head movement. To avoid the variability
introduced due to age and varying degrees of hearing loss, for this initial study young
normal hearing listeners were used. Two types of directional hearing aid processing
were compared to the unaided condition.
Our results show an effect of background noise level and reverberation on subjective
listening effort, an effect on physiological listening effort, as well as a right ear
bias for head direction in increased background noise and reverberation. Hearing aid
type showed a significant effect on deviation angle from the speaker on stage, that is
the difference between where the subject was looking and the location of the actor
speaking on stage. There was also a pattern of speech intelligibility changes with
changing signal-to-noise ratio, which was different based on the type of hearing aid
directional processing.
In addition to listening effort and speech intelligibility, music sound quality can
be greatly affected by hearing aid processing. Live music has additional challenges
compared to recorded music, so ecologically valid studies during live performances
are essential to fully characterize sound quality. Preliminary studies in the LIVELab
and an experiment conducted during an orchestra concert showed that while music
sound quality judgments are subjective and variable between subjects, those with
high musical sophistication are more critical and consistent in their judgments.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract:
While hearing aids are optimized for listening to speech, they still face challenges in
noisy environments and when listening to music. The goal of the studies described in
this thesis was to test hearing aids in realistic noisy environments as well as in a live
concert setting. Our results testing hearing aids in different levels of background noise
in normal hearing listeners showed effects on the effort subjects felt they required
to listen, changes in heart rate, and looking behaviour as they responded to the
additional demands of listening.
From studies in the LIVELab and the concert experiment, it is clear that judgements
of music sound quality are highly subjective and varied between people. Overall
the participants in the concert experiment were very satis ed with the hearing aids
and assistive listening, but we did find that those with more experience with music
were more critical and consistent in their ratings.


title: Functioning and Neurodevelopmental Disorders

title: Examining everyday functioning in family-centred services for children with neurodevelopmental disorders

contributor:
Di Rezze, Briano
Rehabilitation Science

subject:
neurodevelopmental disorders
autism spectrum disorder
function
abilities
parents
family-centred service

abstract: Neurodevelopmental disorders (NDD) refer to conditions that can be present during a child’s early developmental period, and are typically characterized by challenges in a child’s personal, social, academic, or occupational functioning. Autism spectrum disorder (ASD) is an example of NDD, impacting 1 in 66 children in Canada. While interventions vary across this heterogeneous group of impairments, everyday functioning is an important outcome to families. However, this concept of functioning needs further examination with respect to whether and how it is incorporated within the instruments and concepts used in family-centred services (FCS), and how this is understood by parents. This thesis is composed of two studies: a narrative review identifying function-focused measures published in the literature for children with NDD; and a qualitative study examining how parents of children with ASD perceive their child’s abilities in relation to family-centred services. Fourteen clinical measures were described in the review based on how they utilized the International Classification of Functioning, Disability, and Health (ICF) to describe child functioning. In the qualitative study, five themes (Parenting Approaches, Accepting My Child, Managing Child’s Challenges, Doing the Right Thing for My Child, and “The Disability Tag”) were identified as influential factors that can affect how parents perceive their child’s abilities and functioning. As the cultural shift within interventions for children with NDD continue to move beyond the historically prominent deficit-focused lens, and towards the integration of neurodiverse abilities, this study enables us to understand better how concepts of function-focused care are operationalized in family-centred services and intervention systems.

abstract: Thesis

abstract: Master of Science Rehabilitation Science (MSc)

abstract: To support the shift in health care that focuses on the abilities of children with neurodevelopmental disorders (NDD) rather than their ‘problems’ or ‘deficits,’ we need to further understand how family-centred services (FCS) can better fit this change in thinking. This thesis explores paediatric health care focused on addressing ‘everyday abilities’ for children with NDD in research and clinical practice over two studies. Study #1 reviews some of the current ways that everyday functioning is measured in paediatric health care, examining 14 clinical tools developed for children with NDD. Study #2 reports key patterns that describe the experiences of parents of children with autism, in regards to how they think about their child’s abilities, and the care their child receives. Overall, this thesis studied new ways that we can explore the abilities of children with NDD in FCS, specifically concerning how parents and clinicians describe and measure functioning.


title: Structuralist and Individualist Accounts of Racism

title: Finding the Middle Ground in a Polarizing Debate

contributor:
Johnstone, Mark
Philosophy

subject:
Racism
Individualism
Virtue Ethics
Structuralism

abstract: This thesis attempts to demarcate the use of the term “racism” by looking at two of main accounts of what the word means. The first, individualism, defines racism as normally meaning an individual act or attitude of antipathy or apathy towards a person on the basis of their perceived race. The second, structuralism, defines racism as normally meaning the various beliefs, ideologies, laws, and actions that a cultural group participates in as caused by the structures of society which negatively affect a racialized group. I believe that neither of these accounts can adequately define nor address racism. As is shown in chapter III, many of the critiques made against individualism do not adequately answer the major structuralist concerns, but, as is shown in chapter IV, the same can be said for individualist critiques of structuralism. As I show in chapter V, each of them address an important aspect of racism, but fail when they attempt to entirely address it. Both act as a useful evaluative lens, but I will argue that we should be able to use both, rather than have to explain one by using the other

abstract: Thesis

abstract: Master of Philosophy (MA)

abstract: This Thesis discusses individualist and structuralist accounts of racism in an attempt to bridge the two. Many people have discussed this topic in the past 20 years, but nearly all do it from one of these two camps. I propose that we allow for both account to be used in tandom, rather than using one account to explain situations and aspects of situations better explained by the other account.


title: Accelerated Brain Ageing in Mood and Psychotic Disorders

contributor:
Frey, Benicio Noronha
Neuroscience

subject:
mood disorders
psychotic disorders
machine learning
neuroimaging
accelerated ageing

abstract:
Introduction: Through large neuroimaging consortia, researchers have identified a series of neuroanatomical alterations in mood and psychotics disorders, such as major depressive disorder (MDD), bipolar disorder (BD), and schizophrenia (SCZ). However, the mechanism behind these alterations is not well understood. One of the existing hypotheses suggests that the observed brain changes are related to a process of accelerated brain ageing. Studies investigating this hypothesis use a measure called the brain age gap (i.e., the difference between machine learning model predictions of brain age and chronological age). Thus far, there is limited understanding on how mood and psychotic disorders affect model predictions, how can predictions be clinically useful, and what is the biological meaning behind the brain age gap. In this thesis, we investigated accelerated brain ageing in mood and psychotic disorders. We sought to estimate the effect of the brain age gap and propose new ways of modeling brain age. We also explored the clinical utility and meaning of the brain age gap.
Results: We confirmed the presence of a brain age gap in MDD, BD, and SCZ through a systematic review and meta-analysis. SCZ presented the highest levels of brain age gap, followed by BD and MDD. We analyzed the clinical utility of brain age for antidepressant treatment response and concluded that the brain age gap is not a predictor of antidepressant treatment response in weeks 8 and 16. We proposed a new method for brain age prediction that is more interpretable than previous approaches while preserving good predictive performance. We have also used model explanation strategies and identified that the brain age gap is largely associated with total gray matter volume reduction and ventricle enlargement in SCZ.
Conclusion: The results of this thesis suggest that the brain age gap is present across mood and psychotic disorders. The results have also helped to clarify the meaning behind the brain age gap, a largely used but still poorly understood measure in neuroimaging research. So far, there is no indication that the brain age gap can be a useful tool for treatment response prediction in MDD.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Engaging in the world: Investigating the factors that promote civic engagement across 34 countries

contributor:
Kuperman, Victor
Humanities

subject:
civic engagement
volunteering
political efficacy
cross-national

abstract: This thesis investigates the effect that a variety of demographic, educational, cognitive, and health-related variables have on civic engagement. Civic engagement is defined as a combination of frequency of volunteering and feelings of political efficacy. International survey data from 34 countries are used to provide a cross-national view of the predictors of civic engagement. We use canonical correlation analysis to investigate the widespread effects of predictor variables on both facets of civic engagement (volunteering and political efficacy) and the effects that are linked to only one facet. Furthermore, we use country-level socio-demographic data to link patterns of civic engagement of potentially marginalised groups to the representation those groups have at the community level and the political level. Our results highlight the importance of cognitive skills and skill building resources in supporting engaged citizens: literacy skill, numeracy skill, educational attainment, and number of books in the home are found to be strong predictors of civic engagement across all countries. The present thesis contributes to knowledge by employing a common measure of civic engagement across all countries, using an analysis method that allows and accounts for variance shared by multiple facets of civic engagement, and by investigating civic engagement across a wide variety of countries.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: This thesis investigates the factors that affect how involved someone is in their community or society. This involvement is known as civic engagement, which we define as a combination of levels of volunteering and political efficacy (the belief that one can affect politics). A wide variety of potential influencing factors are considered, including literacy and numeracy level, education, health level, and immigration and language background. We use data from an international survey to investigate the effects of these variables on levels of civic engagement in 34 countries. We use a statistical method that highlights how our variables of interest influence civic engagement as a whole, and how the variables specifically influence levels of volunteering or political efficacy. By analyzing the effects of the variables across diverse countries and measures of civic engagement, we shed new light on the factors that promote civic engagement around the world.


title: A multi-modal application of magnetic resonance imaging (MRI) techniques to identify and quantify brain abnormalities in retired professional football players

contributor:
Noseworthy, Michael D
Biomedical Engineering

subject:
magnetic resonance imaging (MRI)
concussion
retired professional athletes
repetitive head trauma

abstract:
High contact sports put athletes at a higher risk of sustaining a concussion. This work focused on assessing regional brain health in aging, retired Canadian Football League (rCFL) players years to decades after retirement. Advanced, quantitative magnetic resonance imaging (MRI) techniques were implemented to identify and quantify microstructural brain white matter damage, cognitive functional signal characteristics (fractal dimension (FD) and amplitude of low frequency fluctuations (ALFF) and fractional ALFF (fALFF)), and cerebral blood flow (CBF) dysregulation.
Due to the high reproducibility of diffusion tensor imaging (DTI) and resting state functional MRI (rsfMRI), a Z-scoring approach exploring outliers relative to a large normative dataset was implemented to examine each rCFL subject individually. However, arterial spin labelling (ASL) data is more sensitive to scanner inconsistencies, therefore a group-wise analysis was performed with the CBF and ASL spatial coefficient of variance (ASL sCoV) data.
Minimal microstructural damage was detected in the rCFL subjects, but a substantial amount of functional and CBF abnormalities were present. The FD was significantly reduced in 48 of 91 regions-of-interest (ROIs) examined, and the four rCFL subjects with the highest number of abnormal ROIs all exhibited worse motor speed, social functioning and general health scores than the other rCFL subjects. Furthermore, the ALFF analysis identified the cerebellum, parietal lobe ROIs, and central sub-cortical ROIs to be consistently abnormal. Finally, the temporal occipital fusiform cortex, superior parietal gyrus, caudate nucleus, and the cerebellum were significantly abnormal bilaterally based on CBF and ASL sCoV values, which also correlated with worse physical functioning and elevated daily chronic pain.
This work adds to the growing literature that brain changes are present later in life that may be related to concussions and repetitive sub-concussive head impacts sustained years earlier. Several consistently damaged ROIs also correlated with adverse clinical presentations to indicate areas of future research.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)

abstract: Clinical concussion assessment has a limited ability to identify brain injury location and severity. Therefore, there is a need for more advanced diagnostic tools to provide meaningful, objective information to concussion patients and clinicians. The work presented in this thesis aimed to assess brain health using magnetic resonance imaging (MRI) techniques of retired professional football players with a complex history of concussions and repetitive sub-concussive impacts. Our research found concussion-related functional and cerebral blood flow brain abnormalities past that of normal aging, but minimal white matter damage, present in the retired athletes that also correlated with clinically testable health metrics such as motor speed, emotional well-being, and pain. Through personalized subject-specific analyses, this work provides further evidence of the effects of concussions later in life.