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What supports and services post COVID-19 do children with disabilities and their parents need and want, now and into the future?
Full text linkIntroduction: Children and youth with disabilities and special healthcare needs, and their families, have been uniquely affected by the COVID-19 pandemic. However, the voices of children themselves are still not well represented in the existing literature. Methods: This qualitative descriptive study used a combination of visual methods and interviews to learn about the experiences of Canadian children with disabilities (n=18) and their parents (n=14) during the COVID pandemic and into the post-pandemic period. Data collection was carried out between January and July 2023. The aim was to identify the supports and services children and families need at present and moving forward. Results: Families’ pandemic experiences were complex and nuanced. For many, the pandemic complicated and disrupted everyday activities and supports. These disruptions were largely buffered by parents. However, some families also identified unexpected benefits. Key themes pertaining to present and future needs included the need for services that are flexible; consistent; conducive to relationship-building; comprehensive; coordinated across sectors; and designed to support the needs of the whole family. Discussion: Implications for policy and practice are outlined
DEVELOPMENT OF AN OPTIMAL PREDICTIVE COLLISION AVOIDANCE SYSTEM FOR HUMAN-ROBOT COLLABORATION
No full textThis thesis presents the development of a collision avoidance system for human robot collaboration applications where a human shares its workspace with a robotic arm. A vision system is used to capture colour point clouds of the shared workspace in real-time. An easy-to-use calibration method is then developed to transform the point clouds to the robot’s coordinate frame. Algorithms for processing the transformed points to obtain models of the human and static obstacle(s), and a method used to model the robot, were developed next. The human is modelled by a plane in front of their torso, and any body parts or objects in the front of this plane are modelled by spheres. This model is more computationally efficient compared to the spheres-only modelling method. Methods for predicting the motions of the human’s arms, head and torso were also developed. Next, two predictive collision avoidance algorithms that account for the system dead time were developed. Five metrics were proposed for evaluating the collision avoidance and trajectory tracking performances of the algorithms. The 1st collision avoidance algorithm is an optimal algorithm, and the 2nd collision avoidance is a non-optimal algorithm. The robotic arm used in this research is an Elfin 5 industrial robot. Simulations of the robot avoiding a static obstacle using the 2nd algorithm demonstrated the necessity of using prediction whenever system dead time is present. Both algorithms were then simulated with a human model moving with a constant speed blocking the robot’s path. Based on the superior performance of the 1st algorithm in collision avoidance and trajectory tracking, it was selected for the rest of the collision avoidance experiments. Three real-time human robot collaboration scenarios requiring collision avoidance were studied experimentally. The experimental results demonstrate the consistent excellent collision avoidance and trajectory tracking performance of the 1st algorithm in all scenarios. The algorithm accelerates the robot to compensate for the time spent performing collision avoidance so that no productivity is lost, unlike many prior approaches. Its computational speed is also faster than other optimal collision avoidance algorithms for human-robot collaboration.ThesisMaster of Applied Science (MASc)People are having more and more interaction and collaboration with robots both in industry and at home. Sharing a workspace with a robot requires the robot to know where the person is, and to avoid contacting them while performing their tasks. In this research, a collision avoidance system for human-robot collaboration was developed to solve this problem. The vision system is developed to capture real-time colour and depth data of the robot and its surroundings. A software algorithm is proposed to model the person by geometric shapes using these data. Two more software algorithms are proposed to control the robotic arm. Both of them worked well when tested using a simulated industrial robotic arm with a significant time delay. The algorithm with the better performance was selected to be tested using the industrial robotic arm in real-time. The results show that the algorithm can consistently move the gripper of the robotic arm to its target location while simultaneously avoiding collisions with the person’s moving body in different human-robot collaboration scenarios
From soft lenses to slim films: functional materials inscribed with waveguide architectures
No full textThis thesis demonstrates the development and characterization of functional materials designed for light guiding and capturing applications. Exploiting the translatable nature of previously developed methods for the self-inscription of complex waveguide lattice architectures, different soft polymer materials are explored for their aptitude for various applications. For a soft material with a quick actuation response an electroactive hydrogel is explored to create dynamic lenses inscribed with waveguides that allow for adaptable light collection and guidance. Conversely, in favour of robustness an acrylate-epoxy blend is used to fabricate radially distributed waveguide lattice slim films that can be integrated with photovoltaics to increase efficiency through enhanced light collection. These films are able to collect light rays at oblique angles that would be otherwise wasted, which is particularly powerful for indoor applications where there is a significant diffuse and isotropic component to lighting.ThesisMaster of Science (MSc
POWERTRAIN CHARACTERIZATION FOR MODELING AND CONTROL DESIGN
No full textUnited States government data shows AWD EV production increasing over 376 % from 2020 to 2023. The literature highlights energy savings from mixed-type dual EM powertrains and optimization-based energy management strategies (EMS), compared to single-type dual-motors and rule-based control. Other trends include the adoption of silicon carbide (SiC) based inverter devices and 800 V systems. Axial-flux machines have seen increased traction, with implementations in Ferrari’s SF90 Stradale, Lamborghini’s Revuelto, and Mercedes-Benz’s acquisition of YASA Ltd.
These findings motivated the study of dual-motor AWD EV thermally constrained energy management. Using McMaster Automotive Resource Centre’s (MARC’s) facilities, accurate modeling of powertrain components was pursued to contribute realistic results.
Firstly, inverter device materials and voltage ratings were studied in a Chevrolet Bolt EV model. Experimental validation was conducted on 1200 V inverters, powering 160+ kW traction machines. The model’s loss error was mostly within 100 W of measured loss. An empirical loss model revealed the analytical model estimates range within 6 km. This work highlighted the benefits of 800 V DC buses and SiC inverters.
Secondly, experimental characterization of a yokeless and segmented armature (YASA) axial flux machine, by YASA Ltd., was documented. Dynamometer tests covered a wide torque, speed, and DC bus voltage range. The Bolt EV was modeled with the YASA machine, comparing its performance to the stock machine. All data was compiled and published in an online open-source repository.
Lastly, thermally constrained energy management of various control strategies for a dual-motor AWD EV model were compared. Over two drive cycles, an MPC strategy ranked best in selected performance metrics. During a racetrack drive cycle, the MPC strategy kept the thermally limited motor cooler 246 % longer than a rule-based strategy. This work highlighted MPC’s potential in reducing total lifetime thermal wear of a dual-motor powertrain’s thermally limited motor.ThesisDoctor of Philosophy (PhD)This thesis presents the experimental dynamometer work behind the accurate modeling of electric powertrain components, specifically the electric machine (EM) and inverter. The analytical inverter model is experimentally validated using electric machines as loads. The electric machine model is constructed from its experimental characterization data. Together, these models form a near-completely experimental-based electric drive unit (EDU). From this foundation, a dual-motor all-wheel-drive (AWD) electric vehicle (EV) model is built for the purpose of evaluating various control strategies’ thermally constrained energy management abilities. The control methods are ranked with respect to key performance indicators (KPIs) over the course of two drive cycles. Results from these drive cycles point to the model predictive control (MPC) strategy achieving the control objectives with the best quantified KPIs. Most importantly, it was able to keep the powertrain's thermally limited motor cooler 246 % longer than the second-best performing control strategy, a rule-based method applying a torque-split ratio algorithm
A Package for the Automated Classification of Images Containing Supernova Light Echoes
Full text linkFUNCTIONALIZATION OF STARCH NANOPARTICLES AND NANOPARTICLE NETWORK HYDROGELS THEREOF AS EXCIPIENTS FOR INTRANASAL DRUG DELIVERY TO THE BRAIN
No full textDelivering drugs to the brain is challenging due to the blood-brain barrier that poses a significant transport barrier for drugs to enter the brain. Those who live with mental disorders such as schizophrenia and bipolar disorder are thus often restricted to routine high dose drug regiments with a wide range of off-target effects outside of the brain. While intranasal (IN) delivery offers potential to deliver drugs with improved efficacy to the brain, this alternative drug delivery pathway is typically limited to potent, short-lasting, or toxic drugs that frequently require re-application, presenting challenges to the practical implementation of IN delivery in treating various mental illnesses including schizophrenia and bipolar disorder. Although currently approved nasal sprays have explored a limited excipients to aid in brain delivery, there is an increasing amount of literature and preclinical trials that demonstrate nanoparticle carriers can improve drug transport.
This thesis identifies a sprayable hydrogel consisting of modified starch nanoparticles (SNPs) and chitosan materials that can gel in situ within the nasal cavity and release ultra-small penetrative SNPs over time. Modifications are rationally selected and optimized in each chapter to complex with each identified gold standard drug to the SNP building blocks that make the up the hydrogels, enabling the effective and prolonged delivery of hydrophobic small molecules (using hydrophobized SNPs), and therapeutic ions such as lithium (using chelating SNPs). By formulating these affinity SNPs into a sprayable hydrogel formulation enabled via Schiff base interactions between chitosan derivatives and lightly oxidized SNPs, a hydrogel depot can be easily administered into the nose that can resist nasal clearance and release the nanoparticle-drug complexes over time, with the SNP-drug complexes subsequently supporting the transport of drugs through the nerves to the brain to maximize treatment duration while also limiting drug release into the blood stream. Both the modified nanoparticles and the hydrogels made from them are thoroughly physically and chemically characterized in vitro and demonstrated to be both safe and efficacious in pre-clinical in vivo rat behavioural models. As such, hydrogel nasal sprays represent a novel excipient to support the efficacy of drug delivery to the brain.ThesisDoctor of Philosophy (PhD)Delivering drugs to the brain is challenging due to the blood-brain barrier that blocks a large portion of drugs we take from reaching the brain. Those who live with mental disorders such as schizophrenia and bipolar disorder are thus often restricted to high dose drug regiments with a wide range of off-target effects outside of the brain. Patients must have routine visits to the doctor to track whether their condition is being managed correctly while also ensuring that drug levels in the blood do not get too high to risk side effects ranging from weight gain, to permanent organ damage, to even death. Intranasal delivery offers potential for delivering drugs to the brain without excessive blood exposure through a direct nose-to-brain nerve pathway. To best travel this pathway, nasal sprays need to have more components than just drugs and water. This thesis aims to address this challenge by creating a hydrogel nasal spray that can stick in the nose and that can slowly release drug-containing nanoparticles over time, enabling improved delivery of various types of therapeutics relevant for treating mental disorders to the brain
EFFECTS OF AIR POLLUTION ON OBESITY AND ECTOPIC FAT DEPOSITION
No full textGlobally, the prevalence of obesity tripled between 1975 and 2016. Alongside well-known risk factors such as an unhealthy diet, sedentary lifestyle, and genetic predisposition, recent studies suggest that air pollution may also contribute to the obesity epidemic. However, evidence remains inconclusive due to variations in demographics, study designs, and types of pollutants examined. Additionally, few studies have investigated the relationship between air pollution and ectopic fat deposition.
This dissertation aims to advance the understanding of ambient air pollution and its association with obesity and body fat distribution. It begins with a systematic review protocol and the resulting systematic review and meta-analysis (Chapters 2 and 3). These are followed by two manuscripts that explore this association using data from a pan-Canadian study. These studies adjust for key covariates and incorporate MRI measures of body fat distribution, including visceral fat, to provide deeper insights (Chapters 4 and 5).ThesisDoctor of Philosophy (PhD)Air pollution may contribute to the obesity epidemic, but evidence remains inconsistent due to varying results across study designs and populations. Little research has examined air pollution’s effects on body fat distribution, particularly visceral fat, which poses significant health risks.
This dissertation explores the links between air pollution and obesity through a systematic review and meta-analysis, and primary analyses of data from a pan-Canadian cohort study. These studies account for confounding factors including age and sex and utilize advanced imaging techniques, such as MRI, to quantify fat deposits. The findings provide valuable insights to inform prevention strategies and improve public health
Disparities in the mental health of migrant children and youth: an analysis of determinants and unmet need
No full textBackground: Global migration has significantly increased in recent decades, emphasizing the need to understand and address the mental health needs of migrant populations, particularly children and youth who face unique challenges pre-, during-, and post-migration. Despite these challenges, evidence suggests conflicting mental health patterns. Some studies suggest migrant children and youth experience fewer mental health difficulties compared to their non-migrant peers – a pattern often referred to as the “healthy migrant paradox,” while other studies challenge the phenomenon. This thesis examines differences in mental health problems and access to care between migrant and non-migrant children and youth, and identifies social and contextual factors that may mitigate or attenuate group differences. Methods: Three manuscripts address key objectives: (1) a systematic review and meta-analysis of 59 studies quantifying differences in mental health outcomes among migrant and non-migrant children and youth in high-income countries; (2) an analysis of differences in mental health-related service contacts between migrant and non-migrant children and youth, and social and economic factors that account for between group differences using a large, representative sample of children and youth in Ontario, and (3) an investigation into the moderating effect of migrant concentration in schools and the mediating role of school processes (loneliness and belonging at school) in the association between migrant background and mental health symptoms, using advanced epidemiologic methods including structural equation modelling and multilevel moderated mediation models. Results: Overall, the fundamental findings of this body of work are: 1) substantial heterogeneity exists in current evidence, influenced by substantive and study methodological factors; 2) after accounting for mental health symptoms and perceptions of need, migrant children and youth, compared to their non-migrant peers, were significantly less likely to have mental health-related service contacts; 3) adjusting for social and economic factors did not fully account for between group differences in mental health-related service contacts; 4) the concentration of migrants in schools is associated with lower levels of externalizing symptoms for migrant youth when migrant concentration is high, and this effect is mediated by youth feelings of loneliness at school. Conclusions: Together, these papers provide a comprehensive understanding of migrant mental health among children and youth. They underscore evident heterogeneity in mental health outcomes among migrant and non-migrant children and youth, influenced by a number of socio-contextual and economic factors. The findings highlight consistent evidence of mental health service shortfalls for migrant children and youth.DissertationDoctor of Philosophy (PhD)This thesis examines differences in mental health outcomes and service use between migrant and non-migrant children and youth. It examines risk and protective factors that contribute to group differences. It provides a comprehensive understanding of mental health needs through a dual focus on symptoms and service use. The objectives were addressed through three manuscripts: (1) a systematic review and meta-analysis quantifying mental health differences among migrant and non-migrant children and youth in high-income countries; (2) an analysis of social determinants associated with mental health service use in Ontario, revealing significant underutilization by migrant children and youth; and (3) an investigation into the role of migrant concentration in schools, highlighting its protective effects on mental health outcomes for migrant youth through reduced feelings of loneliness at school. This work offers insights that can inform policies and programs designed to improve access to care and promote the mental health and well-being of migrant and non-migrant children and youth
EDI AS A FORM OF INSTITUTIONAL ACTIVISM: CANADIAN UNIVERSITIES’ FIGHT AGAINST RACIAL INEQUALITY
No full textCan university EDI offices actually reduce racial inequalities? Should we consider their efforts on social change to be activism? The question of eradicating inequalities has been at the centre of socio-political issues in our society in the last few decades. Universities have made commitments to eradicate - or at least reduce - inequalities as they project an image of progressiveness and inclusion. Accordingly, Canadian universities have promoted their EDI (Equity, Diversity, and Inclusion) initiatives more rigorously, especially in the wake of the proliferation of protest actions in support of Black Lives Matter (BLM) and #StopAsianHate. As universities began to show support for these social movements by providing official statements to the public, their efforts were construed as activist by right-wing pundits, while being regarded as largely symbolic and ineffective by scholars. Using insights from social movement theory and the sociology of education, I examine the possibilities and constraints of EDI offices in top English-speaking Canadian universities. In this case study of institutional approaches to racial inequality, I conduct in-depth interviews with seven of the top EDI officers in Canada and examine statements published by university officials to consider the social change goals and actions of U15 universities. I have three main findings. First, EDI leaders in Canadian universities cannot necessarily be considered social movement activists, but rather are best described as institutional mediators in advancing social issues toward social changes within institutions. Second, when universities make public statements about racial inequalities, and even when they make commitments to produce social change, their actions and claims fall short of activism, refraining from using the motivational framing of a call to action. Finally, I find that while adding resources to EDI offices does increase universities’ bureaucratic capacity to address racism, this institutional opportunity for social change does not translate into action on all anti-racism issues. Specifically, Canadian universities have been much more vocal and active in responding to demands of the Black Lives Matter movement than to the demands of the #StopAsianHate movement. I argue that the EDI practices of Canadian universities should not be considered a form of institutional activism, as I identify gaps between the institutionalized promotion of social issues and what would be considered a social movement agenda. This research contributes to the sociology of education literature, supporting its skeptical view about the effectiveness of EDI efforts within universities, while providing original insights on how universities’ EDI practices fall short of their stated goals in reducing racial inequality. In addition, it makes contributions to social movements theory’s understanding of organizational activism, expanding its understanding on the constraints on social change within organizations, impacting not only the outcomes of efforts to reduce inequality, but also the goals envisioned by EDI officers in the first place and restricting claims-making rhetoric. Overall, this research reflects that barriers embedded within universities based on institutional and cultural values are still main forces in delaying and hindering more progressive social change.DissertationDoctor of Philosophy (PhD)Universities have made commitments to eradicate or reduce inequalities as they project an image of progressiveness and inclusion. Canadian universities have promoted their EDI initiatives more rigorously, especially in the wake of the proliferation of protest actions in support of Black Lives Matter and #StopAsianHate. As universities began to show support, their efforts were construed as activist by right-wing pundits, while being regarded as largely symbolic and ineffective by scholars. Using insights from social movement theory and the sociology of education, I examine the possibilities and constraints of EDI offices in top English-speaking U15 Canadian universities. I conduct in-depth interviews with seven of the top EDI officers and examine statements published by university officials to consider the social change goals and actions of universities. First, EDI leaders in Canadian universities cannot necessarily be considered social movement activists, but rather are best described as institutional mediators. Second, when universities make public statements about racial inequalities and producing social change, their actions and claims fall short of activism, refraining from using the motivational framing. Finally, while adding resources to EDI offices does increase universities’ bureaucratic capacity to address racism, institutional opportunity does not translate into action on all anti-racism issues. I argue that the EDI practices of Canadian universities should not be considered a form of institutional activism, as I identify gaps between the institutionalized promotion of social issues and a social movement agenda
WhileCC-approximability and Acceptability of Elementary Functions
No full textIn this thesis, we study models of computation for partial functions on the reals. Existing work [Fu and Zucker, 2014, Tucker and Zucker, 1999, 2004] studies classes of computable partial functions on R, namely
• GL-computability,
• tracking computability,
• multipolynomial approximability, and
• WhileCC-approximability.
Fu and Zucker [2014] show that all these four models of computation are equivalent when we restrict our attention to a specific class of functions we call “acceptable” functions.
This means, within the realm of acceptable functions, we can work with WhileCC-approximability without giving up expressivity and transfer results amongst the models. However, it was previously unknown whether the class of acceptable functions is sufficiently large to include many common functions, such as the elementary functions. In this thesis, we solve the conjecture posed by Fu and Zucker [2014] and show that all elementary functions are acceptable. We also prove that the elementary functions are WhileCC -approximable and therefore computable in all the aforementioned models of computation.ThesisMaster of Science (MSc)Several models of computability were previously proposed for partial functions over the
reals. Some of these models were proved to be equivalent for functions satisfying specific
conditions we call “acceptability”. In this thesis, we prove that at least the class of elementary functions satisfies this “acceptability” condition. This shows that the acceptability
conditions are sufficiently general