Restricted Theses and Dissertations
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- ItemEmbargoOptimization of Autonomous Goods Delivery Systems in Urban Areas(2024-06-21) Lamb, Jacob Steven; Wirasignhe, Chan; Waters, Nigel; DeBarros, Alexandre; Saidi, SaeidThe freight sector is growing: disruptions in this sector have accelerated and are coming under more public scrutiny than other technological changes in the past. Autonomous goods delivery technologies are such a disruption, vehicles with no human on-board that can travel along roads, sidewalks, or in the air. Without the constraint of a human driver, many different forms and functions of vehicle can be created. It is uncertain the type or design of autonomous vehicle that will be best suited for exactly what scenarios, the strategies that will be used to operate them, and the supporting infrastructure changes that will be needed to best accommodate them. This thesis provides planning tools for this change that industry and government can utilize for better, quicker, and more transparent decisions. These methods also allow for sensitivity analysis and the impacts of technology changes to be considered and investigated. The impacts that uncrewed aerial vehicles (UAVs) and sidewalk autonomous delivery robots (SADRs) will have on the optimal locations of micro-fulfilment centers (MFCs) and mothership vans (MSs) are analyzed. It is found that the sensitivity of the relationship between stock-turnover by area and the optimal number of MFCs is a barrier to the adoption of UAV and MFC systems. Moreover, delivery time-windows are shown to be a primary motivating factor in the adoption of UAVs and the areas of a region that are most cost-effective for the switch to UAV and MFCs are the areas furthest from existing logistics centers. For SADRs working with MS, two distinct deployment strategies are identified and compared, then the breakeven cost points for these strategies are analytically determined and expressed in a decision matrix table. A series of sensitivity analysis scenarios shows how exurbs and further suburbs of urban areas are most cost-effective to move to MS with SADR systems. Finally, UAVs and SADRs are compared simultaneously, and a mixed fleet system considered and optimized with conventional vans. The numerical study of Singapore shows that increasing the autonomy of UAVs and SADRs is a key barrier for more widescale adoption.
- ItemEmbargoPericyte deficiencies in a foxf2 loss of function mutant(2024-06-26) Graff, Merry Faye; Childs, Sarah; McFarlane, Sarah; Grewal, SavrajPericytes are critical players in vascular development and disease but are not widely studied in the context of cerebral small vessel disease, a vascular condition related to stroke that progressively weakens brain microvessels. Foxf2, a pericyte-expressed gene, is involved in vascular stability and reduced FOXF2 is associated with increased stroke risk and CSVD prevalence. Here, I use a zebrafish foxf2a loss of function mutant as a genetic model of CSVD to show pathological alterations in brain pericytes. Not only are there fewer brain pericytes across the lifespan, but these pericytes also exhibit morphological abnormalities like increased soma size, process length and degeneration. These abnormalities manifest differently in adult brains, and blood vessel defects are evident. I show that embryonic pericyte defects are not the result of decreased pericyte density but a combination of cell-autonomous and non-cell-autonomous effects. A downstream target of foxf2a, loxl2b, is downregulated in foxf2 mutants. While loxl2b mRNA is sufficient to boost brain pericyte numbers, mutants for this gene do not show an obvious phenotype, suggesting a more complicated role. This thesis sheds light on novel lifespan defects in mutant brain pericytes, potentially contributing to vascular destabilization, and opens new avenues for studying genetic forms of human cerebral small vessel disease.
- ItemEmbargoInnovative Universal Severity Classification System for Natural Disasters(2024-06-25) Caldera, Hallupathirage Jithamala; Wirasinghe, Sumedha Chandana; Kattan, Lina; Ruwanpura, Janaka Yasantha; Saidi, SaeidAssessing the true impact of natural disasters is complex, varying by type, location, and time period. Natural disasters, ranging from minor fires to cataclysmic super-volcanic eruptions, universally affect living beings and their habitats. No single factor captures all aspects of impact, as different factors convey varying perspectives on severity, and not all factors are equally significant. Disasters are frequently categorized based on criteria like fatalities or financial damage, but existing classifications often lack a scientific foundation to capture the overall impact, leading to inconsistent measurements and management. The absence of a coherent, globally accepted standard for communicating disaster severity complicates effective disaster management, as varied interpretations hinder unified response efforts. Diverse scales, such as the EF-Scale for tornadoes and the VEI scale for volcanic eruptions, are used to measure disaster magnitude. Various stakeholders—emergency responders, humanitarian aid workers, medical personnel, insurance managers, media, and civilians—employ different scales and terminologies, creating coordination challenges. Disconnected measurement systems cause confusion, hinder relief and mitigation efforts, delay resource allocation, and can lead to political and social instability, affecting international security and relations and causing long-term negative impacts for affected regions. To address these issues, this dissertation introduces the Dis-Utility-Based Universal Disaster Severity Classification System (DUDSCS), a novel framework for assessing and comparing the severity of natural disasters. The DUDSCS integrates both quantitative and qualitative criteria, the former employing 'dis-utility functions' to identify key severity factors and their relationships. Factors such as fatalities, injuries, homelessness, affected populations, and economic damage are evaluated to provide a comprehensive measure of event severity. The development of the DUDSCS involved a six-step methodology, starting with the adoption of 'random dis-utility theory' derived from choice modeling in random utility theory. A global survey captured perceptions, resulting in over 6,000 responses used to calibrate and validate the dis-utility model. Additionally, an in-depth analysis of over 13,000 historical disaster records and their probability distribution helped establish the system's quantitative criteria. By offering a consistent, multidimensional assessment tool, the DUDSCS enhances communication and coordination among stakeholders. By addressing inconsistencies in disaster terminologies and providing a common communication platform, the DUDSCS promotes better-prepared, more resilient communities. The qualitative classification system, while originally in English, can be adapted to other languages using clear definitions for each level based on impact degree, circumstances, fatalities, injuries, and damage. A color-coding system assists disaster recovery workers who may be illiterate or unfamiliar with the local language, enabling effective communication and response in foreign regions. This ensures that all individuals, regardless of language or literacy barriers, can understand and respond to disasters efficiently. This scale captures varying levels of severity, making it a valuable tool for diverse stakeholders, including policymakers, disaster managers, insurance estimators and researchers. The DUDSCS framework provides a new 0 to 10 scale for event severity, where zero indicates minor impact and ten signifies partial or full extinction. The research includes a case study on the COVID-19 pandemic, demonstrating the system's applicability and addressing key gaps in disaster literature. The system aligns with global frameworks such as the Sendai Framework for Disaster Risk Reduction 2015-2030, contributing to targets related to reducing disaster impacts on lives, economies, and infrastructure. Despite challenges such as data biases and predictive limitations, this comprehensive, statistically sound DUDSCS marks a significant advancement in disaster impact assessment and management, fostering informed decision-making and effective resource allocation for disaster preparedness and response.
- ItemEmbargoHighly Dexterous Robotic Insertion Tube for Enhanced Minimally Invasive Surgical Procedures(2024-06-24) Topham, Matthew Jory; Amrein, Matthias; Federico, Salvatore; Willetts, Lian; Betram, John E.A.Current surgical robotic and endoscopic systems permit minimally invasive access to numerous anatomical sites and have demonstrated many benefits by improving diagnostic capabilities, patient outcomes, and treatment efficiency. These advances are not without limitations, as current systems are designed for access to a narrow range of anatomical sites through the requirement of specific sites of entry (natural conduits or straight-line access) and minimal dexterity. Here, I propose to greatly broaden the capabilities of surgical robotic systems through the creation of a highly dexterous and discretely configurable robotic insertion tube for enhanced minimally invasive surgical procedures. A priority of this system, which I term Serpento, is usability in small settings, including remote and rural communities. As such, this system is designed to be cost-effective and suited for mass production. The ability to assume a vast number of discrete and defined configurations allows Serpento to provide access to currently inaccessible tissue and travel independently of natural conduits (i.e. the colon). At its core, the robotic insertion tube underlying Serpento is comprised of a sequence of several hundred ring components, that are each individually addressable teeter-totter mechanisms. The unique structure, formed by the assembly of these components, improves the maneuverability of the system, which allows it to precisely follow complex access paths. Furthermore, a central channel may contain tubes for suction, for example, or to allow for the advancement of tools as seen in current endoscopes. Serpento has become a tangible possibility through computer-aided design (CAD), 3D printing, and assistance by Dr. Matthias Amrein and Dr. Salvatore Federico. Ultimately, the innovative work behind Serpento has demonstrated promising results, laying the foundation for its advancement from a conceptual design to a feasible technology.
- ItemEmbargoExamining Chronic Post-Stroke Aphasia Recovery Using Non-Invasive Brain Stimulation and Neuroimaging(2024-06-24) Low, Trevor A; Dukelow, Sean; Goodyear, Bradley; Kirton, AdamAphasia, an impairment in language processing, affects approximately one-third of stroke survivors immediately after stroke and up to 50% will have long-term impairments. Rehabilitation of aphasia at the chronic phase is possible, though outcomes are variable and often minimal. Novel therapeutic approaches and an increased understanding of the neurobiology supporting recovery are needed. Chapter Two assessed the safety and feasibility of combining repetitive transcranial magnetic stimulation (rTMS) with high-intensity Multi-Modality Aphasia Therapy (M-MAT) in chronic post-stroke aphasia (n=20). This novel combination therapy was determined to be feasible and safe in chronic post-stroke aphasia. On the basis of all participants benefiting from M-MAT regardless of rTMS allocation, we used resting-state fMRI (Chapter Three) and diffusion-weighted MRI (Chapter Four) to examine functional and structural connectivity associated with changes in speech production. In individuals that made positive, significant changes in naming, pre-treatment functional and structural connectivity of left hemisphere temporal and parietal language regions were associated with greater treatment-related improvement in naming. Additionally, naming improvements were associated with decreases in functional connectivity of bilateral posterior temporoparietal regions with frontoparietal, sensorimotor and visual networks at post-treatment. In Chapter Five, we conducted a randomized controlled trial investigating the efficacy of rTMS plus M-MAT on aphasia severity in a larger cohort of chronic stroke participants (n=43). Delivery of rTMS combined with M-MAT resulted in significant supplemental improvements in aphasia severity compared to sham plus M-MAT at follow-up. This demonstrates that rTMS is a promising adjuvant therapy for M-MAT in chronic stroke. Chapter Six investigated the neural basis of adjuvant rTMS effects using overt naming fMRI. Participants who received rTMS with M-MAT demonstrated dynamic functional reorganization over time, resulting in increased recruitment of left hemisphere perisylvian and temporoparietal regions at 15 weeks compared to sham. These data demonstrate potential mechanisms for the behavioural improvements observed following rTMS plus M-MAT. This thesis provides evidence to support the efficacy of rTMS plus M-MAT for improving chronic post-stroke aphasia. In addition, this thesis advances our understanding of the structural and functional brain architecture that supports aphasia recovery. These behavioural and neuroimaging results are important for the advancement of post-stroke aphasia rehabilitation.