VictorJuiz/thesis huggingface dataset:
The Effect of Walkway Incline Angle on Balance Control in Healthy Older Adults and Ankle Foot Orthosis Wearers with Lower Motor Neuron Pathologies

Navigating a slope carries additional demands compared to level ground, that may be amplified in older adults or individuals with mobility impairments. This study intends to understand the effect of walkway incline angle on balance control in healthy older adults and ankle foot orthosis (AFO) wearers. Twelve healthy older adults (>60 years of age) and four AFO wearers (>60 years of age) ascended and descended slopes ranging from 0° to 8°. AFO wearers completed the protocol with and without their AFOs. Older adults and AFO wearers had a minimum margin of stability that was larger during descent and less during ascent. AFO wearers walked more cautiously, with a wider stance and larger margin of stability in the anterior direction. The results may provide clinicians with information on how orthosis use affects dynamic balance during sloped gait and provides a basis for future work informing environmental design.

Advisor: Novak, Alison C
Knowledge-based Isocenter Selection in Radiosurgery Planning

We study knowledge-based isocenter selection approaches in radiosurgery planning. In particular, we want to leverage recent advances in deep learning to predict isocenter locations in treatment plans in order to reduce costs and provide decision support. We begin by investigating desirable mathematical properties for the representation of treatment plans, which leads us to introduce the notion of tumor spaces. Our method can be summarized as follows: (1) compute and normalize tumor spaces, (2) compute shape descriptors for each tumor space and corresponding isocenters in order to reduce dimensionality, (3) train a residual neural-network on computed shape descriptors, and (4) predict isocenters for a given out-of-sample case using trained neural-network and (5) apply inverse transform to obtain result in voxel domain. Finally, our network was trained on 533 patient cases and was validated on the out-of-sample set of cases. Our numerical results indicate a positive predictive value of the proposed method.

Keywords: computer vision
isocecenter selection
orthonormal polynomials
residual networks
tumor spaces
Advisor: Aleman, Dionne M
Ruschin, Mark
Four Shades of Gray: Understanding the Effect of Visual Contrast on Step Edges to Improve Safety

Stair falls during descent are a dangerous and costly occurrence. Contrasting tread edge highlighters have been shown to improve measures of stair safety, however the necessary contrast magnitude of these aids has not been investigated. Data from thirteen older adults (age; 67.7 ± 5.5 years) were analyzed as individuals completed stair descent trials under normal and low lighting conditions, blurred and normal vision, and four different contrast levels between the tread edge highlighter and the staircase. Cadence, foot-to-step clearance, and degree of foot overhang were determined for all conditions, and were significantly affected by contrast level. Blurred vision was observed to be a greater factor influencing biomechanical measures of fall risk than low ambient lighting. Results suggest higher contrast highlighters improve measures of safety, even more so during simulated vision impairment, and that at least 50% contrast difference may be necessary to provide adequate visual information for safer stair ambulation.

Keywords: Contrast
Falls
Stair descent
Stair safety
Tread edge highlighter
Visual impairment
Advisor: Novak, Alison C
Privacy Protection against Passive Monitoring using SDNs

In traditional networks, an adversary compromising forwarding elements (FEs) (switches, links, routers) can passively observe network layer headers of traffic and infer sensitive information such as sender-receiver pairs, encrypted passwords and so on. To address this, we present TrafFu, a system that protects network layer headers from passive monitoring using software defined networks (SDN). TrafFu encrypts end-host identifiers in packet headers (IP addresses) at the source. FEs rely on a trusted controller to decrypt the packets and provide forwarding rules. TrafFu encrypts successive packets with different keys, thus increasing the cost for an adversary trying to infer sensitive information. TrafFu's main drawback is that it increases flow table utilization on FEs, which we measure in our evaluation. We also propose a method to allow some aggregation of flows to reduce flow table pressure at the cost of some loss of privacy, and study this trade-off.

Keywords: Networks
Passive Monitoring
Privacy`
Security
Software Defined Networks
Surveillance
Advisor: Lie, David
Rendering Reconciliation and Reconstruction Technical: Engineering, the Rule of Law, and Depoliticizing Effects on Disaster Recovery and Transitional Justice in Nepal

The year 2015 saw the convergence of several nationally significant events in Nepal, including the formation of a Truth and Reconciliation Commission (TRC), two devastating earthquakes, and the creation of a National Reconstruction Authority (NRA) to coordinate post-earthquake reconstruction. In this thesis, I discuss reconciliation and reconstruction as they are conceptualized through Nepal’s TRC and NRA, respectively. Drawing on data from qualitative interviews and document analysis, I consider how discourses of development and national unity are embedded in state projects of reconstruction and reconciliation and what sorts of knowledge and expertise are prioritized in these processes. Using a critical development framework, I argue that by narrowly focussing on specialized domains of engineering and law, respectively, the NRA’s housing grant program and the TRC’s reconciliation processes are rendered technical and enact individualized, depoliticized, “development”-oriented approaches that leave intact ongoing structural violence, national exclusion, and inequalities.

Keywords: development
disaster risk reduction
earthquake reconstruction
Nepal
transitional justice
truth and reconciliation commission
Advisor: Rankin, Katharine
The Tale of Two Aminophosphines: Exploiting the Ramirez Mechanism to Access Difluoroenolate Chemistry using Trifluoromethyl ketones

Selective aliphatic C-F bond cleavage of trifluoromethyl ketones mediated bytris(dialkylamino)phosphines are explored to access difluoroenolate chemistry. Two aminophosphines derivatives are investigated: P(NMeCH2CH2)3N (me-VB) and P(NEt2)3. The me-VB/B(C6H5)3 FLP reacts with 2,2,2-trifluoroacetophenone to generate difluoroalkenyl phosphatrane (DFEP). The azaphosphatrane structure disallowed access to difluoroenolate chemistry under mild conditions. Difluoroenolate chemistry was accessed when reacting me-VB with 2,2,2-trifluoroacetophenone in the absence of B(C6H5)3 to generate the aldol-homoadduct product. Switching the aminophosphine to P(NEt2)3 enabled the formation of difluoroalkenyl phosphonium (DFEPn3) when reacting with 2,2,2-trifluoroacetophenone in the presence of B(C6H5)3. The acyclic phosphonium character of DFEPn3 enabled facile access to difluoroenolate chemistry using fluoride or hydroxide as the nucleophile. The first example of converting 2,2,2-trifluoroacetophenone to 2,2-difluoroacetophenone at room temperature using main-group compounds is reported.

Keywords: Difluoroenolate
inorganic
Main-group
metal-free
organofluorine chemistry
Trifluoromethyl ketone
Advisor: Stephan, Douglas W
An Improved PMU Model for Voltage Response in Transient Stability Simulation

Large scale power networks are typically simulated only on transient stability analysis (TSA) software. This is sufficient when modelling slow moving ac quantities is of interest and is much faster than using time domain electromagnetic transient programs. However, TSA tools are not capable of modelling the subcycle dynamics well. Since wide-area measurement systems are practically only modelled on TSA software, while evaluating potential phasor measurement unit (PMU) based control schemes, researchers/utilities depend on TSA results to approximate PMU measurements. This is not sufficient to ensure adequate real-world performance. This research focused on creating a test bench for characterising the dynamic performance of PMUs. Using voltage magnitude data from this test bench, an improved PMU model for transient stability simulation has been created. The model achieves fits of over 97% across the test cases it was validated with, which is a substantial improvement over the raw TSA simulation results (63-77% accuracy).

Advisor: Tate, Joseph Euzebe (Zeb)
Student-athlete Disclosures of Psychological Distress: Exploring Experiences of University Coaches and Athletes

Student-athletes are noted to be a high-risk population for experiencing psychological distress, and varsity coaches have been identified as support providers for distressed athletes; however, little is known about the interactions between student-athletes and their coaches when athletes disclose psychological distress. Therefore, the purpose of this research was to explore the experiences of student-athletes disclosing psychological distress to coaches from the perspectives of both athletes and coaches. Semi-structured interviews were conducted with 15 student-athletes and 15 varsity coaches, and data were analyzed using a thematic analysis. Results indicated that student-athletes faced barriers in disclosing distress and that the involvement of coaches in the disclosure process resulted in either a positive and negative athlete experience, depending on the support coaches provided. Findings provide insight into the role of coaches in supporting distressed student-athletes, how coaches can foster team cultures that support athlete disclosure, and guidelines for effective coach support.

Keywords: Coach-Athlete Relationship
Coaches
Communication
Mental Health
Sport
Student-Athlete
Advisor: Tamminen, Katherine
Vessel Network Extraction via micro-CT Imaging: A Foundation for Modelling Lung De- and Recellularization

Complete re-endothelialization of de-endothelialized pulmonary circuits in lungs remains a significant challenge in restoring functionality to regenerated lungs. Current methods of delivering endothelial cells to distal vessels during re-endothelialization have only been partially successful, leading to the incomplete regeneration of the pulmonary circuit. Understanding the root cause for poor cell delivery is a key first step in improving lung re-endothelialization. In this thesis, pulmonary circuits in native and de-endothelialized mouse lungs were processed using micro-computed tomography and custom analysis algorithims for assessing the preservation of the pulmonary circuit of de-endothelialized lungs. Vessels in the pulmonary circuits of native lungs were characterized at previously unattainable resolutions and accuracies. Characterization of de-endothelialized lungs showed significantly fewer distal vessels and an incomplete pulmonary circuit. The consequence of cell absence post re-endothelialization suggests significant physical obstructions to cell delivery, rather than an inability of cells to form functional distal vessels.

Keywords: Decellularization
Imaging
Lungs
Micro Computed Tomography
Tissue Engineering
Vasculature
Advisor: Bazylak, Aimy
Activatable Probes for Anti-Cancer Therapy

Light is an external control tool that is therapeutically useful. One application is the photocaging of cancer drugs whereby a light responsive group (photocage) renders the drug inactive initially and active upon light irradiation allowing for spatial and temporal control of the drugs release. This work highlights the utilization of photocages for the development of light-activatable inhibitors for O6-Methylguanine DNA Methyltransferase, an enzyme that confers cancer cells resistance to chemotherapeutic drugs. Another application of light is in photodynamic therapy whereby light is used to activate a drug, called a photosensitizer, allowing its reaction with local oxygen to produce toxic oxygen species. In particular, this work highlights the hypoxia-induced activation of a photosensitizer in cancer cells. This photosensitizer is activated by a Nitroreductase, an enzyme that is only functional under low oxygen conditions, thereby limiting its cytotoxic effects to hypoxic cells without inducing damage to surrounding healthy cells.

Keywords: Cancer
MGMT
NTR
PaTrin-2
Photocage
Photodynamic therapy
Advisor: Beharry, Andrew
Dry Coupling of High-temperature Ultrasonic Transducer Components

Our goal was to acoustically couple the high temperature ultrasonic transducer components selected in previous studies for operation up to 800°C. The transducer components selected were a lithium niobate piezoelectric crystal, a porous zirconia mechanical backing, and a stainless-steel 321 protective layer. A thin sheet of annealed silver was used as a coupling agent. It was found that placement of annealed silver foil at each interface of the ultrasonic stack and between the transducer stack and test piece resulted in acoustic coupling of the entire stack with a clamping force of 2 kN (25.5 MPa) after three loading cycles. The resulting echo had a Signal to Noise ratio greater than 25 dB and a half-power (-3 dB) bandwidth of ~65%. This is compared to a Signal to Noise ratio of 32 dB and a half-power (-3 dB) bandwidth of ~65% when all interfaces were coupled with ultrasonic gel (ideal performance).

Keywords: Dry Coupling
High - Temperature
Transdcuer
Ultrasound
Advisor: Sinclair, Anthony N
Risk Factors for Oral Antibiotic Therapy Failure in Cystic Fibrosis-related Pulmonary Exacerbations

Objective: Risk factors were investigated to find associations with oral antibiotic failure in cystic fibrosis (CF) related pulmonary exacerbations (oPEx). Methods: Patients from the Toronto CF Database were selected if they had ≥1 episode of oPEx (2009 to 2017). Failure to recover ≥90% of baseline lung function (non-response) was analyzed using a logistic regression within a generalized estimating equation. Results: Overall, 605 patients had 2970 oPEx episodes and 567 (19.1%) episodes were associated with treatment non-response. The factors independently associated with increased risk of non-response were older age at oPEx, greater baseline lung function, lower BMI and chronic inhaled antibiotic use. Infections due to Achromobacter spp., Burkholderia cepacia complex infection and Staphylococcus aureus were also identified as risk factors of nonresponse after treatment. Conclusions: Specific factors can help identify which patients with oPEx are at higher risk of oral antibiotic treatment failure and help decision making around management.

Keywords: Antibiotics
Cystic fibrosis
Pulmonary exacerbations
Risk factors
Advisor: Daneman, Nick
A Retrospective Analysis of Multiple Dental Implant Failures

Purpose: To identify and compare possible risk indicators associated with failure of multiple versus single dental implants Materials and Methods: A retrospective analysis was performed on patients with more than one implant who had experienced biological failure of one or more implants at the Faculty of Dentistry, University of Toronto (January 1979 to June 2018). Data was used to identify possible factors associated with multiple dental implant failures and compare these factors between individuals with single and multiple implant failures. Associations between various factors and multiple implant failure were reported. Results: Excluding history of implant failure, the following factors were found to be associated with MIF: machined surfaces, post-operative infections, presence of certain prostheses opposing the implant, periodontitis, alcohol consumption, history of chemotherapy, and use of antidepressants. Conclusions: Provision of implant-based care for patients presenting with factors associated with multiple implant failure should be undertaken with caution.

Keywords: cluster phenomenon
implant success
implant survival
loss of osseointegration
multivariate analysis
risk indicators
Advisor: Chvartszaid, David
Azarpazhooh, Amir
Life after Sexual Assault: Post-traumatic Growth and Quality of Life in Survivors

Posttraumatic Growth (PTG) is a potential outcome of trauma that consists of positive life changes. PTG has been found to occur in various populations of trauma survivors. However, PTG in survivors of adult sexual assault may differ from PTG in other populations. This study investigated levels of PTG in adult female survivors of sexual assault, as well as its relationship with quality of life and posttraumatic stress symptoms (PTSS). Three potential mediators were also examined: social support, helpfulness of disclosure to another person, and commitment to activism. Though participants did report significant levels of PTG, PTG was not found to relate to quality of life or PTSS. Significant correlations were found between: PTG and social support; PTSS and social support; PTSS and helpfulness of disclosure; and disclosure and social support. Social support was also found to predict PTSS independent of PTG. Implications for clinical interventions and future research are discussed.

Keywords: Posttraumatic growth
Posttraumatic stress
Quality of life
Rape
Sexual assault
Sexual violence
Advisor: Stermac, Lana
Dispossession and Violence: A Textual Analysis of State Repression of Indigenous Women in Central India

The thesis is an exploration of the relationship between institutional violence against women in Central India and the agenda of land dispossession. I focus on these connections within the state while paying attention to the social relations between the neoliberal- capitalist class to understand the political economy of the state that enacts the land acquisition and the subsequent land dispossession of its indigenous inhabitants. I further examine the gendered impact of this process and how the state apparatus reproduces the patriarchal structures to create a system of oppression of the indigenous women. I explain that a necessary strategy of such expansion of the state is violence against Adivasi women. The study is a textual analysis and adopts a Marxist feminist framework of analysis to study the complex relationship of state repression through sexual violence against women. I intend to inform activist agendas and academic scholarship on violence against women.

Keywords: capitalist patriarchy
dispossession
neoliberalism
sexual violence
state repression
Advisor: Mirchandani, Kiran
The Effects of Virtual Reality-induced Postural Threat on Performance of a Walking Balance Task

Rapid motor learning may occur in situations where individuals perceive a threat of injury if they do not perform a task well. This may be facilitated by improved motor performance and consequently, more errorless practice. The purpose of this study is to determine if performance of a motor task improves in situations where perceived threat of injury is high. I hypothesized that perceived threat of injury in a virtual environment will result in improved performance of a walking balance task. The addition of perceived threat of injury yielded slightly greater, but not statistically significant, balance performance in virtual environments. These results may be partially attributed to habituation to threat over time and practice. A more robust threat manipulation may reveal greater differences in motor performance between high- and low-threat conditions. If implemented carefully, virtual reality technology can be an effective tool for investigating walking balance in environments perceived as threatening.

Keywords: Fear
Motor Skills
Virtual Reality
Walking
Advisor: Mansfield, Avril
Pre-TMS Phase of Ongoing EEG Oscillations Modulates Cortical Activity Response at the Prefrontal Cortex

Background Rhythmic brain activity and its influence on the brain, remains to be elucidated. Our study aimed to evaluate the influence of pre-TMS phase of different rhythms in the brain on the TMS-induced potential (TIP) through TMS-EEG at the dorsolateral prefrontal cortex (DLPFC). Objective To investigate the relationship between pre-TMS phase and TIP. Methods This study involved 19 healthy controls who underwent single pulse TMS at the DLPFC and M1. Alpha (8-13 Hz), beta (14-30 Hz), theta (4-7 Hz), and delta (1-3 Hz) were analyzed. Normalized TIP amplitudes were compared at the positive peak (0±30°), negative peak (180±30°), and random phase. Results At the DLPFC, a significant increase was found in AUC25-250 at the peak of the delta rhythm (Mdn=105.6%) compared to the negative peak (Mdn=93.06%), z=3.99, p

Keywords: closed-loop
depression
dlpfc
magnetic
stimulation
tms
Advisor: Daskalakis, Zafiris J
Wong, Willy
Investigating the Role of Insulin Receptor Signaling in B Lymphocyte Function

B cells drive insulin dysregulation during obesity and type 2 diabetes, but little is known about how insulin affects B cell functions. Using a B cell-specific insulin receptor (InsR) knockout model, we show that InsR signaling promotes pro-inflammatory processes and proliferation in B cells. InsR deficiency also impairs B cell production of pro-inflammatory cytokines. Interestingly, InsR signaling contributes towards Th1-associated antibody class switching. In a model of severe influenza A (H1N1) viral infection, mice with B cell-specific InsR deletion show increased susceptibility and have compromised humoral responses. During high fat diet-induced obesity, mice lacking InsR on B cells are protected from insulin resistance and glucose intolerance and show reduced fat inflammation. Mechanistically, InsR signaling reinforces glucose uptake and glycolytic function to support B cell functions. Taken together, our work highlights the importance of InsR signaling in driving optimal B cell function in health and disease.

Keywords: B cell
Diabetes
Immunology
Insulin
Advisor: Winer, Daniel A
Alzheimer’s Disease Pathophysiology and Risk Factors with Amyloid Positron Emission Tomography, an Open Science Approach, and the Consideration of Environmental Exposures

Alzheimer’s disease (AD) is the most common underlying cause of dementia but is incompletely understood. The pathophysiology of AD involves amyloid-beta plaques, neurofibrillary tangles, and cerebrovascular changes involving white matter. Risk factors including lead (Pb) exposure influence these processes. This thesis has four components related to improving the understanding of AD pathophysiology. First, amyloid positron emission tomography (PET) tracer delivery was hypothesized to be associated with white matter integrity and was demonstrated to be correlated with established biomarkers in mild cognitive impairment. Second, an open source software package for PET analysis was created to improve transparency in AD research. Third, a systematic review of case-control studies of Pb measurement in AD is presented, which highlights the possible connection but identifies a need for studies that address early-life Pb exposure. And fourth, a hypothesis that environmental microdose lithium may mitigate Pb toxicity including cognitive impact is outlined with several literature reviews.

Keywords: Alzheimer's
cerebral blood flow
dementia
lead
positron emission tomography
R (programming language)
Advisor: Graff-Guerrero, Ariel