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Development of Capacitive Wearable Sensors for Limb Volume Measurement Towards Swelling Management
No full textLymphedema represents a chronic medical condition characterized by progressive limb swelling due to compromised lymphatic drainage, affecting millions of people globally and necessitating continuous monitoring for effective clinical management. Current assessment methodologies rely predominantly on infrequent clinical measurements and subjective evaluations, creating substantial gaps in patient care protocols and treatment optimization strategies. This research addresses these critical limitations through the development of an advanced wearable sensing system utilizing highly stretchable capacitive strain gauge (HSCSG) technology for continuous limb volume monitoring applications in people living with lymphedema.
The investigation employed a systematic methodological approach encompassing comprehensive literature review, advanced fabrication technique optimization, multiphysics simulation modeling, and extensive experimental validation protocols. Following thorough comparative analysis of available sensing modalities, capacitive sensing utilizing interdigitated electrode (IDE) array configurations was selected based on superior linearity characteristics, minimal drift properties, and enhanced compatibility with wearable electronics applications. Direct ink writing (DIW) fabrication processes were systematically optimized for IDE sensor production, incorporating thermoplastic polyurethane (TPU) substrate materials selected for their advantageous mechanical properties in wearable electronics implementations (Chapter 3). A novel sensor generation software platform was developed to enhance fabrication precision and manufacturing repeatability, while comprehensive COMSOL Multiphysics simulation studies provided detailed design space optimization guidance (Chapter 4).
The research successfully developed optimized HSCSG sensors demonstrating linear sensing response capabilities extending to 25% mechanical strain while approaching theoretical gauge factor sensitivity limitations. Extensive characterization protocols confirmed exceptional durability performance under high elongation conditions and cyclical loading environments (Chapter 5). A novel limb volume phantom model (LVPM) incorporating pneumatic artificial muscle technology was developed for comprehensive sensor calibration and validation procedures, enabling precise assessment of circumferential monitoring capabilities with minimal calibration requirements (Chapter 6).
This comprehensive study established significant contributions to the field of soft robotic sensing both scientifically and technologically. These contributions include: i) enhanced understanding of IDE capacitive sensor behavior under large mechanical deformations, ii) innovative DIW fabrication protocols optimized for stretchable electronics applications, and iii) practical validation methodologies for wearable sensing system implementation, which collectively provide a robust foundation for future clinical deployment in lymphedema monitoring applications
Turing Instability of a Closed Nutrient-Phytoplankton-Zooplankton Model with Nutrient Recycling
No full textWe investigate Turing instability in a closed Nutrient–Phytoplankton–Zooplankton (NPZ) ecosystem that incorporates delayed nutrient recycling, formulated as a reaction–diffusion system. Although spatial diffusion typically enhances system stability, our study focuses on how differing diffusion rates among species can destabilize steady states and lead to the emergence of spatial patterns. To explore this, we first perform a linear stability analysis to identify the conditions under which Turing instability arises. These theoretical predictions are then validated through numerical simulations. Our study progresses systematically: beginning with a two-species model, extending to a threespecies system, and finally to a four species NPZD model. This stepwise framework provides both conceptual insight and quantitative understanding of how diffusion influences instabilities, offering a comprehensive perspective on pattern formation in multi-species plankton ecosystems
Target Selection and Shareholder Value Implications in Operating Synergy-Driven Mergers
No full textThis study examines whether resource similarity in product and geographic market positions, as well as resource quality similarity, affects the likelihood of related mergers aimed at operating synergies. I classify five value-creation sources of operating synergies: cost efficiency, market position, product portfolio, geographic expansion, and innovation resources. Product and geographic market resources are critical to achieving these value-creation goals, while variation in resource quality among potential targets possessing the necessary resources indicates different gains acquirers can retain from synergy distribution.
I estimate conditional logit models for target selection analyses and ordinary least squares regressions for shareholder wealth effect analyses. The results show that all three dimensions of similarity increase merger likelihood, although their effects vary across value-creation contexts. I find evidence consistent with acquirers’ expectations of net gains from synergy distribution when selecting targets exhibiting product similarity and resource quality similarity, as reflected by closer Tobin’s Qs.
Product similarity consistently increases merger likelihood, yet its effect on acquirer shareholder wealth depends on the specific value-creation motive, reflecting its varying relevance across goals. Resource quality similarity primarily matters in product-enrichment-driven mergers. Its varying effect across value-creation contexts likely depends on the substitutability of the resources sought by acquirers. Geographic proximity increases the likelihood of operating synergy-driven mergers other than innovation-driven ones, but does not affect shareholder wealth outcomes. Its effect on merger likelihood appears driven by reduced information asymmetry between nearby firms, which may not enhance shareholder wealth creation.
This study adds new evidence on the determinants of target selection and merger performance across distinct value-creation contexts of operating synergies. This study also advances the literature on resource quality similarity by enriching evidence on its positive effect on merger likelihood and providing the first empirical evidence that the substitutability of the resources sought by acquirers moderates the strength of the positive relationship. The findings also indicate that requiring disclosure of primary reasons for mergers upon announcements may enhance acquirers’ decision-making and external monitoring in operating synergy-driven mergers
Chitosan/SIFSIX-3-Cu Cryogels on Printed Laser-Induced Graphene for CO2 Electric Swing Capture
No full textTo achieve global net zero greenhouse gas emissions, carbon dioxide (CO2) removal technologies (CDR) must be deployed at gigatonne scale by the end of the decade. Direct air capture (DAC) is one category of CDR technology which shows promise due to its more straightforward measurability and verifiability. Low temperature, solid sorbent-based DAC systems in particular offer a lower energy demand and when paired with renewable electrical systems, avoid the use of fossil fuels and the generation of additional CO2 emissions in the process. Several sorbents have been investigated for electric swing adsorption (ESA) DAC, where heat generated using the Joule heating principle is used for the desorption of CO2 from the sorbent. Most of the sorbents are carbonaceous due to their semi-conductive nature which allows for electrical current travel. However, these sorbents suffer from reduced capacity at low CO2 partial pressures, making them less suitable for DAC.
As an alternative, we explore an indirect ESA process using laser-induced graphene (LIG) which acts as a flexible heater layer. For the adsorbent layer, chitosan (CS) cryogel with in situ synthesized SIFSIX-3-Cu metal organic framework (MOF) is fabricated for its high capacity, appreciable CO2 selectivity, and sustainability. The pure MOF powder reached its maximum adsorption capacity of approximately 2.5 mmol g⁻¹ within just five minutes, demonstrating its exceptionally fast adsorption kinetics. In contrast, the pure chitosan (CS) cryogel required more than 30 minutes to reach the same capacity. The CS/MOF hybrid cryogel exhibited intermediate kinetics, achieving a maximum adsorption capacity of 2.92 mmol g⁻¹. It was shown that the adsorbents could be regenerated in temperature range of 70-80°C, had low N2 uptake, and 88% of the CS/MOF cryogel capacity was maintained after 4 cycles. Patterned LIG grids were subsequently fabricated and could raise the temperature of the CS/MOF cryogel adsorbent via Joule heating to the target regeneration temperature in 66 s with only 15 V. The LIG grid could also consistently generate the desired temperature range over 4 cycles. Lastly, the chitosan cryogel was fabricated directly on a LIG grid without compromising its heating capability. This successfully demonstrates how an environmentally conscious and efficient ESA system can be engineered by combining LIG optimized for heating and eco-friendly adsorbents with high CO2 capacity
Assessing the Economic Viability of Nature-Based Solutions as an Urban Heat Island Mitigation Strategy: A Framework for York Region
No full textThis thesis examines the economic viability of urban greenery cover (GC) as an urban heat island (UHI) mitigation strategy for York Region, Ontario. In light of increasing urban temperatures and intensifying heat stress, including the UHI effect, a comprehensive cost-benefit analysis (CBA) framework is developed to evaluate two distinct GC scenarios (moderate and intense). The analysis integrates a range of direct benefits – such as reduced emergency department visits, avoided premature mortality, decreased energy consumption, and increased productivity – alongside indirect benefits, including improved air quality and enhanced biodiversity. A key innovation in this thesis is the incorporation of a non-linear tree canopy scaling factor into the benefit valuation process, recognizing that urban tree benefits, such as air quality and those resulting from cooling effects, do not accrue at a constant rate. The study applied a quadratic scaling function to reflect the gradual maturation of tree canopies over a 40-year project horizon. This adjustment enables a more accurate projection of economic returns by emphasizing the higher benefits realized as trees reach full maturity. Cost components, including initial installation and ongoing maintenance expenses, are also discounted at an annual rate of 3%, following established regulatory guidelines. Overall, the results demonstrate that both GC scenarios yield negative net present values (NPV) and benefit-cost ratios (BCR) of 0.01. However, when non-linear scaling is incorporated, the timing and magnitude of benefits are more accurately projected, reflecting ecological phenomena in an economic model. These findings not only advance the methodological framework for assessing the economic viability of nature-based solutions (NbS) in urban environments but also offer practical insights for policymakers and urban planners seeking to justify investments in urban GC as a means of mitigating the UHI effect and adapting to climate change
“Jails are not the shelters battered women need”: A Feminist Genealogy of Domestic Violence Criminal Legal Interventions in Ontario from 1980 to 2000
No full textFor the past four decades, criminal legal interventions, such as mandatory arrest and specialized courts, have characterized the dominant response to domestic violence (DV). The predominately American literature has shown that criminalization has failed to decrease rates of violence against women (VAW) and support victims, is reactionary rather than intervening early to end abuse, and has led to the heightened criminalization of women victim-offenders. Building on this literature, this Canadian genealogical study shows how the criminal legal system came to be seen by many as a logical component of the Ontario VAW movement and its consequences on women criminalized for DV. This research utilizes a unique pairing of insights from feminist genealogy and Institutional Ethnography (IE) to analyze hundreds of historical records and 30 interviews with VAW activists, front-line service providers and criminal legal officials who were active during the 1980s and 1990s. With this weaving of theoretical and methodological tools, I reveal the narratives used by the dominant VAW movement in Ontario to frame experiences of violence that contributed to placing the response to DV within the purview of the criminal legal system. In addition, I show how activism at the community-level created protocols and legal interventions that were governed locally and implemented by front-line workers and institutional actors informed by the feminist lenses of their local advocates. I then trace the governance of the DV criminal legal interventions from their communities of origin to the expansion by the Ontario provincial government, demonstrating how the expansions contributed to the criminalization of women victim-offenders. I also interrogate the consequences of the DV criminal legal interventions on women experiencing violence and marginalized communities more broadly and explore the acts of resistance some advocates and front-line workers engage in to counter the harms of these interventions. Lastly, I draw attention to three historical strategies that existed prior to the expansion of the DV Courts that create opportunities for advocates, service providers, criminal legal officials and governments to intercede differently to address the contemporary problems of increasing rates of DV and criminalization of women victim-offenders. By interrogating historical records and centring the perspectives of participants, my study contributes important Canadian perspectives of how the DV criminal legal interventions in Ontario coordinated people’s actions as they relate to the carceral response to women arrested for domestic assault. In addition, through the inclusion of both institution-based and community-based archives, I demonstrate a methodological strategy for including marginalized voices when conducting historical research. My research also expands the use of IE into the study of the criminal legal system and their community-based partners and contributes to the broader feminist literature that interrogates the collaboration of advocates and the state in criminalizing VAW
Exploring the Impact of Childhood Adversity on Adolescent Executive Function: The Role of Pubertal Timing
No full textAdverse childhood experiences (ACEs) have been consistently associated with negative impacts on individual’s health and development including, but not limited to, changes in pubertal timing and the development of executive function; however, whether pubertal timing mediates the association between ACEs and executive functioning remains unknown. To address this gap, data was leveraged from a large-scale, nationally representative sample of American adolescents (Adolescent Brain Cognitive Development Study; N = 11,878, 52% male, 52.4% White, 13.4% Black, 24.0% Hispanic). Concurrent models assessed the integrity of adolescents’ core executive function abilities via their performance on tasks of response inhibition, working memory, and cognitive flexibility (baseline assessment; 9-10 years), whereas prospective models examined adolescents’ day-to-day executive functioning in life via parent ratings of their behavior (Time 5 follow-up assessment; 12-13 years). For females, but not males, earlier pubertal timing mediated pathways between greater ACE exposure and executive functions at both time points: at baseline, this was reflected in lower levels of performance on executive function tasks and at follow-up parent endorsement of executive function challenges in everyday living. These findings suggest there may be sex-specific pathways through which early adversity experiences impact subsequent development, with puberty emerging as a particularly important consideration for females vis-à-vis adolescent refinements in their capacity for cognitive self-regulation
Housing Public-Private Partnerships in Toronto’s Regent Park
No full textThis thesis explores the evolution of public-private partnership (PPP) in Toronto’s housing development. PPP is defined as a legal and economic framework in which public and private sectors share resources, risks, and responsibilities in delivering projects or services traditionally managed by the government. The study first traces the model’s emergence in 1980s Toronto, where it arose as a response to fiscal constraints and administrative inefficiencies, particularly in infrastructure and affordable housing initiatives. After the late 1990s, the model was widely employed in Toronto to address housing challenges—leveraging public land and private capital to develop mixed-use, mixed-income, and mixed-tenure communities. These developments sought to combine private-sector efficiency with public-sector goals of affordability, spatial equity, and sustainability.
Focusing on the redevelopment of Regent Park as a case study, this thesis critically analyzes the effects and limits of PPP-operated housing in contemporary Toronto. Originally constructed in the 1940s as Canada’s first public housing project, Regent Park faced decades of physical decay, social isolation, and stigmatization. In 2005, the Toronto Community Housing Corporation (TCHC) launched a major redevelopment to transform the area into a vibrant, mixed-income neighborhood. Drawing on archival research and fieldwork, the study investigates the collaboration among the City of Toronto, TCHC, and the Daniels Corporation at both political-economic and spatial levels. It assesses the model’s spatial manifestations, advantages, and shortcomings—particularly issues of gentrification, displacement, and placelessness—while situating the case within a broader international context of PPP-operated housing projects. Finally, through a design-based inquiry into the Phases 4 and 5 of Regent Park, the thesis proposes a new public-residential typology that seeks to dissolve the spatial segregation between market-rate and affordable units, mitigate placelessness, and foster community integration and historical continuity. In doing so, it offers a transferable design strategy for the global implementation of PPP models in affordable housing. This design proposal responds directly to the spatial and social limitations of the PPP model, offering a pragmatic intervention rather than a utopian vision. At the same time, it embeds a critical stance toward the neoliberal housing paradigm by reimagining the relationship between public and private, affordability and profit, architecture and equity
Quantifying Endplate Deflection in Response to Cyclic Load Exposures Using a Porcine Cervical Spine Model
No full textThe vertebral endplate is a thin layer of cartilage and bone that separates the intervertebral disc from adjacent vertebral bodies and facilitates the transmission of compressive force through the spine. Despite this essential function, it remains the weakest component of the vertebra-disc unit and is highly susceptible to mechanical failure. Endplate failure typically arises from localized tensile strains that manifest as deflection, defined as the out-of-plane displacement of the surface under load. While prior work has demonstrated inferior endplates of intervertebral joints exhibiting greater deflection and higher incidence of failure than their superior counterpart, current techniques for quantifying endplate deflection face notable limitations.
Early studies using metallic markers or displacement transducers required drilling channels into the vertebral body, potentially exaggerating deformation by weakening subchondral bone support. Imaging-based approaches, particularly micro-CT, offer high spatial resolution but are limited to static or stepwise loading due to temporal constraints. These static conditions do not capture the cyclic loading patterns experienced by the spine during daily activity, where repeated deformation can cause fatigue-induced microdamage and eventual failure. Additionally, static loading promotes excess fluid loss from the nucleus pulposus, altering endplate deflections in ways that do not reflect physiological motion. Consequently, existing measurement techniques may misrepresent true endplate behavior and are unable to evaluate changes in deflection as a function of cyclic load exposure. This study addresses these limitations by developing a unique method to assess endplate deflection during cyclic loading without requiring prolonged stepwise protocols or causing damage to the vertebral bone. By comparing superior and inferior endplates across different load magnitudes and cyclic durations, this work aims to clarify the mechanisms underlying endplate vulnerability and further validate the porcine cervical spine as an experimental model for human lumbar spine deflection.
Eighteen porcine cervical spine functional units (C3C4, C4C5, and C5C6; n = 6 per level) were dissected to yield 36 individual vertebrae. High-resolution laser profilometry was then used to capture the topography of the caudal endplates of C3, C4, and C5 and the cranial endplates of C4, C5, and C6. Custom indenters, designed as negative molds of the nucleus-occupying endplate region, were created from the resulting surface scans and fabricated via 3D printing. Specimens were then oriented such that the tested endplate was in a neutral position and subjected to a normalized haversine waveform, ranging from 0.3 kN to 30% of the predicted ultimate compressive strength using a servohydraulic materials testing system. The cycle-dependent changes in endplate deflection were measured at 0, 1000, 3000, and 5000 total cycles. At each time point, endplate deflection measurements were captured via the indenter’s displacement while specimens were exposed to a brief static force of 0.3 kN, 1 kN, and 3 kN, totaling 12 measurements per vertebra. Three separate linear mixed effects models were used to evaluate the impact of loading magnitude, loading cycles, endplate level and the proportion of the nucleus occupying endplate area on superior and inferior endplate deflection within each joint. A fourth linear mixed effects model was used to evaluate the impact of loading magnitude, loading cycles, and joint level on the magnitude of the differences between superior and inferior endplate deflection.
Utilizing this novel methodology, this study was the first to quantify endplate deflection under cyclic loading conditions, observing greater deflection of the inferior endplate across all spinal levels, except at baseline (0.3 kN, 0 cycles). This method also enabled comparison of deflection rates between endplates, with the C4C5 and C5C6 inferior endplates showing a significantly greater rate of deflection during the first 1000 cycles. Among joints, C4C5 exhibited the largest difference in superior and inferior endplate deflection compared to C3C4 and C5C6. Endplate deflection was not influenced by the proportion of the nucleus occupying endplate area at any spinal level. Lastly, as the first study to examine endplate deflection in porcine cervical vertebrae, the observation of greater inferior endplate deflection being consistent with human cadaveric studies further supports the validity of this model. Overall, this study demonstrates the utility of a novel methodology for measuring and comparing superior and inferior endplate deflection under cyclic loading
Development of High Strength Aluminum Alloys for Directed Energy Deposition Additive Manufacturing
No full textAmong additive manufacturing (AM) techniques, directed energy deposition (DED) is of particular interest for structural Al alloys, as it combines the faster cooling rates with the flexibility to repair or build large-scale geometries. The localized thermal cycling inherent to the DED process influences solidification behavior, grain refinement and precipitate evolution for high strength age-hardenable Al alloys such as Al 7075, which in turn governs the mechanical performance. These capabilities position DED as a promising pathway for expanding use of high strength heat-treatable aluminum alloys in aerospace and automotive applications where a good strength to weight ratio is crucial. However, Al 7075 tends to crack during solidification and possesses a limited service temperature range. The research conducted explores the tailoring of an existing Al 7075 composition and delves into the development of novel Al alloy compositions for DED-AM processes.
In the initial phase of the research, laser-directed energy deposition of Al 7075 wire feedstock enhanced with TiC nanoparticles to promote grain refinement was investigated. It was found that the combination of high laser power (3400 W) along with low travel speed (400 mm/min) and low wire feed speed (400 mm/min) resulted in the reduction of lack of fusion defects and reducing cracks within the multilayer prints. However, substantial evaporation during printing led to a reduced amount of Mg and Zn bearing phases in the as-printed samples. It was shown that the direct aged sample heated for 5 hours was of comparable hardness to the T6 (solution heat treated and then artificially aged) sample (115 HV0.5), which highlights the presence of solute trapping in the as-printed material.
To compare the behavior of the same Al 7075 + TiC wire feedstock under arc-based solidification conditions, the research continued to investigate the microstructural evolution and mechanical response of Al 7075 reinforced with TiC nanoparticles processed via arc-based DED, with a particular focus on aging behavior. Grain refinement was primarily attributed to heterogeneous nucleation and grain boundary pinning by TiC clusters. Moreover, TiC inoculants influenced solute redistribution, driving segregation of Mg and Cr, which in turn altered the precipitation behavior during aging. Heat-treated samples revealed the co-formation of MgZn₂ strengthening precipitates and the E-phase (Al18Mg3Cr2), with the latter contributing to the heterogeneous distribution of precipitates. These findings highlight both the benefits and challenges of TiC inoculation in tailoring microstructure and age-hardening response in arc-DED processed Al 7075 alloys.
The second phase of the research presents the design and evaluation of a novel Al-Ce-Mg alloy tailored for wire arc-DED. The objective was to overcome the limitations of conventional high-strength aluminum alloys, which suffer from solidification cracking, volatile element loss, and poor thermal stability at elevated temperatures. Alloy selection was guided by CALPHAD simulations, leading to the identification of a near-eutectic Al-10Ce-9Mg composition. Thin-wall structures were fabricated, and porosity was quantified using micro-computed tomography, supported by high-speed imaging that revealed oxide-film entrapment as the dominant cause of porosity. The solidified microstructure consisted of α-Al, eutectic, and primary Al₁₁Ce₃ phases, as well as β-AlMg phase, which contributed to both strength and thermal stability. Compression testing demonstrated high room-temperature strength but brittle failure. At elevated temperatures, however, the alloy retained superior strength compared to conventional precipitation-strengthened Al 7075 alloy, even after extended thermal exposure. This observation was attributed to the stability of Al-Ce intermetallics.
Incorporation of Sc into Al-Ce-Mg alloys can provide a dual strengthening and thermal stabilizing effect. Therefore, in the final phase of the conducted research, an Al-8Ce-8Mg-0.2Sc alloy was developed. Laser surface remelting was employed to replicate AM-like conditions, producing a refined bimodal grain structure and fragmenting coarse Al₁₁Ce₃ networks into discontinuous, blocky morphologies. Compared to the as-cast state, the remelted alloy exhibited increased hardness (114.5 HV1 vs 133 HV1), aided by refined grains and secondary phases such as Al11Ce3 and Mg2Si. Direct aging produced an irregular hardening response, with peak hardness achieved at 375 °C for 1 h due to the precipitation of coherent Al₃Sc nanoprecipitates. Long-term thermal exposure at 200 °C for up to 1000 hours showed negligible hardness loss and minimal coarsening of Ce-bearing intermetallics. Strengthening contributions were dominated by Al₃Sc precipitation, supported by solid-solution, grain refinement, dislocation hardening, and stable Al₁₁Ce₃ dispersoids