VictorJuiz/thesis huggingface dataset:
Neuroimaging of Brain Iron in Schizophrenia

Schizophrenia is an often severe and chronic psychotic disorder. Although many disease mechanisms have been explored, the biological basis of schizophrenia remains elusive. Additionally, the elevated lifetime risk of suicide in schizophrenia implies there may be an unknown pathophysiology underlying the two. Our objective is to explore the correlation of brain iron, which is known to modulate dopamine synthesis, in schizophrenia and suicide. For samples of schizophrenia subjects and healthy controls, as well as individuals with schizophrenia at high and low risk for suicide, brain iron levels in the substantia nigra were investigated using quantitative susceptibility mapping. Although there were no differences in brain regional iron levels, volumes of the substantia nigra may be reduced in patients with SCZ and further reduced for those at high risk for suicide. The present study encourages further research on iron levels and deep grey matter nuclei in the pathophysiology of schizophrenia and suicide.

Keywords: Neuroimaging
Schizophrenia
Suicide
Advisor: De Luca, Vincenzo
Using Accelerated Testing to Indicate Later-Age Chloride Ingress and Bulk Resistivity of Concrete

Supplementary Cementitious Materials (SCMs) are used in concrete to help improve the durability of the hardened concrete and to reduce global warming potential. Ambient curing does not provide enough time for the SCMs to develop their potential by 28 days, as they typically require 91 days, as allowed in CSA A23.1. Use of optional accelerated curing allows for SCMs to develop more of their potential by 28 days and speed up evaluation for construction acceptance. This study aims to promote the use of accelerated curing for evaluation of SCM concretes in terms of strength, Rapid Chloride Permeability Test (RCPT), and Bulk Electrical Resistivity Test data. These tests were conducted on both cylinders and cores extracted from slabs on concrete mixtures with varying levels of SCMs. The results were then compared to determine if accelerated curing test data can be used for acceptance. The correlation between cylinder and core results are discussed, as well as the correlation between the RCP and bulk resistivity test data. The results show that accelerated curing provides similar or lower permeability results.

Keywords: Concrete
Durability
Permeability
RCPT
Resistivity
SCMs
Advisor: Hooton, Doug
Emergency Dental Care in a Paediatric Hospital during COVID-19

PURPOSE: To investigate the impact of the COVID-19 pandemic on patient demographics, presenting dental conditions, and treatment provided in the Emergency Department (ED) at The Hospital for Sick Children (SickKids) in Toronto, Ontario. METHODS: A retrospective chart review of dental-related ED complaints during the pandemic period (March 16, 2020 to March 15, 2021) were reviewed and compared to pre-pandemic period (June 2, 2018 and March 15, 2020). Demographic and clinical data were collected. RESULTS: There was a significant increase in patients of lower socioeconomic status (SES) presenting to the ED during the pandemic (p=0.019). The prescription of oral anti-infectives (p=<0.0001) and dental extractions (p=0.0006) increased significantly during the pandemic compared to the control period. CONCLUSIONS: Patients presenting to the ED during the pandemic were of lower SES, further highlighting pre-existing oral health disparities in Canada. Restrictions during the pandemic contributed to increased emergency management with oral anti-infectives and dental extractions.

Keywords: COVID-19
DENTAL CARE
DENTAL EMERGENCIES
PEDIATRIC DENTISTRY
Advisor: Garisto, Gabriella A
Understanding Ventilator-Induced Lung Injury: The Role of Mechanical Power

OBJECTIVES: To assess the association between high (> 17 J/min) dynamic mechanical power (dynMP) within the first 24 hours of invasive mechanical ventilation (IMV) and ICU mortality, and determine a critical threshold of dynMP affecting mortality rates. METHODS: Adult patients with acute hypoxemic respiratory failure requiring IMV were included. Propensity score weighting and logistic regression models were used, and a change-point regression model was applied. Secondary outcomes included duration of mechanical ventilation and ventilator-free days. RESULTS: Analysis involved 9,135 patients. High dynMP was associated with increased ICU mortality. The relationship was non-linear, with a steep incline at low dynMP levels. No single and reproducible dynMP threshold was identified. High dynMP reduced extubation rates and ventilator-free days. CONCLUSIONS: High dynMP within the first 24 hours of IMV was independently associated with increased ICU mortality. Reducing dynMP at initiation of IMV may be a promising strategy to reduce mortality.

Keywords: acute hypoxic respiratory failure
intensive care medicine
invasive mechanical ventilation
mechanical power
threshold analysis
ventilator-induced lung injury
Advisor: Fan, Eddy
Investigating the Orthotic and Acute Therapeutic Effects of a Novel Upright Balance Therapy for Individuals with iSCI and Developing a New Clinical Version

Individuals with incomplete spinal cord injury (iSCI) experience an increased rate of falls due to decreased sensorimotor function. We demonstrated in a prior longitudinal pilot study that a therapeutic system using functional electrical stimulation and visual feedback balance training (FES+VFBT), produced therapeutic effects in individuals with iSCI. However, the exact role and mechanism FES in the system is not understood. Additionally, hardware and software limitations make clinical application of the system difficult. In this thesis, I determined the orthotic and acute therapeutic effect of FES in the FES+VFBT system and developed a new clinical version of the system. The FES demonstrated an orthotic effect by increasing ankle stiffness and an acute therapeutic effect by increasing corticospinal excitability. A new clinical version of the system was successfully recreated using the Wii Balance Board and Unity game engine and was proven to perform at least on par with the lab-based system.

Keywords: Functional Electrical Stimulation
Quiet Standing
Rehabilitation
Visual Feedback Training
Advisor: Masani, Kei KM
Design of Multi-component Alloy Catalysts Aided by Density Functional Theory and Machine Learning

Catalysts are a key pillar in countless industrial processes and represent key components to some of the worlds most important solutions regarding climate change. As a result, increasingly complex systems such as Binary and High Entropy Alloys are being studied to improve performance. For these systems, the large configurational spaces require high throughput techniques such as machine learning to properly study but current methods are not perfect. This thesis presents four advancements in scientific insight and methodologies to accelerate computational catalyst design. Firstly, a bottom up approach utilizing simpler catalysts systems to design increasingly complex electrocatalysts is presented. Secondly, a novel Machine Learning technique is proposed to elucidate mechanistic insight for these increasingly complex alloy systems. Thirdly, a techno-economic pipeline is designed to optimize the alloy electrocatalysts. Lastly, an improved graph representation technique is presented that allows for more universal ML frameworks with improved catalyst discovery capabilities.

Keywords: Alloys
Catalysis
Data Science
Density Function Theory
Machine Learning
Advisor: Singh, Chandra Veer
A Mesoscopic Central Limit Theorem for Sample Covariance Matrices and their Linearization

We consider sample covariance matrices of the form $X^TX,$ where $X$ is an $M\times N$ random matrix with independent entries. We prove a central limit theorem for random variables of the form $\tr f(X^TX)$ where $f$ is taken to be a smoothed out indicator function. In order to establish this result, we first prove an analogous result for the linearized matrix, $\big(\begin{smallmatrix} 0 & X^T \\ X & 0 \\ \end{smallmatrix}\big)$.

Keywords: Central Limit Theorem
Random Matrix Theory
Sample Covariance Matrix
Advisor: Landon, Benjamin
A Micro Flow Reactor for Studying Pollutant Formation

Soot formation from combustion of hydrocarbons is a key contributor to the environmental impact of energy use. Conventional research burners for combustion studies provide great insight into flame sooting behaviour, but are not able to discern the early phases of pollutant formation due to the interdependence of the flow fields and flame conditions. Micro flow reactors isolate the flow field effects and present a controlled chemical and physical environment, thus being ideally suited to study pollutant formation at flame conditions in a tractable setting. In this thesis the design and evaluation of a novel micro flow reactor is presented. This reactor is operable with liquid fuels up to 1350 K, and provides optical and physical access for a variety of diagnostics. Implemented diagnostics include soot measurement by gravimetric and optical methods, and gas composition analysis through gas-chromatography--mass-spectrometry. The reactor was evaluated using 4 liquid hydrocarbon fuels in the C_7 range with different chemical features. This was done under near flame conditions, and the expected behaviour from these evaluation fuels was observed, showing a high sensitivity in studying polycyclic-aromatic-hydrocarbon and soot formation processes. The micro flow reactor is found to be a promising tool for future pollutant formation studies.

Keywords: Combustion
Extinction
GCMS
Micro flow reactor
Pollutants
Soot formation
Advisor: Gülder, Ömer L.
Effect of Sleep Restriction on Cerebrovascular Health and Neurocognition in Healthy Adolescents

Background: Sleep restriction (SR), defined as a sleep duration below the basal need of an individual, is pervasive in adolescents and identified as a global public health concern by the American Academy of Paediatrics. This study aims to understand the role of SR on magnetic resonance imaging measurements of cerebral vascular function in adolescents and whether, and to what extent, it is a modulator for cognitive impairment. Methods: This randomized crossover study recruited healthy adolescents (age 15-to-18 years-old) who underwent: 2-nights of baseline sleep, 5-nights of longer sleep (9 hours of sleep opportunity), minimum 2-nights of washout period, and 5-nights of experimental SR (6 hours of sleep). Cognitive and cerebrovascular health outcomes were compared between SR and longer sleep periods. Results: Significant impairment to aspects of cognitive function, and changes in cerebrovascular health were seen with SR. These findings suggest an association between SR, cerebrovascular function and cognitive function.

Advisor: Narang, Indra
Dlamini, Nomazulu
Regulation and Pro-fibrotic Role of Myocardin-related Transcription Factor A Signaling in Stressed Right Ventricular Fibroblasts

Fibrosis contributes to right ventricular (RV) failure in RV pressure-loading. Myocardin-related transcription factor A (MRTF-A) is known to regulate fibrosis, but its regulation in pro-fibrotic gene expression, as well as whether established crosstalk between MRTF-A with pro-fibrotic effectors yes-associated protein (YAP) and its paralog transcriptional co-activator with PDZ-binding motif (TAZ) also occurs in RV fibroblasts, remains unknown. With aurora kinase A (AURKA) emerging as a potential regulator of MRTF-A signaling via RhoA in fibroblasts, we hypothesized that AURKA regulates RhoA signaling and consequently MRTF-A to drive pro-fibrotic gene and YAP/TAZ expression in stressed RV fibroblasts. We confirmed that MRTF-A increased pro-fibrotic gene and TAZ expression in response to transforming growth factor - beta 1 (TGF-B1) stress and RhoA activation. AURKA inhibition reduced MRTF-A nuclear translocation and pro-fibrotic gene expression, but not TAZ, in TGF-B1 stressed RV fibroblasts, possibly through the RhoA effector guanosine nucleotide exchange factor H-1 (GEF-H1).

Advisor: Friedberg, Mark
Early Life Sleep Loss Impacts Sociality in Drosophila melanogaster

Decades of behavior genetics research offer the consensus that fruit flies demonstrate sleep and social behaviors. Though the effects of early-life sleep deprivation on dyadic social interactions in Drosophila melanogaster have been characterized, little is known about its effects on their group behavior. In this study, we used social network analysis (SNA) to characterize the impacts of early-life sleep deprivation on network interactions of adult Canton-S strain D. melanogaster. Through our bivariate experimental design, we sleep deprived flies at two different ages (newly eclosed and 6-d old) and acquired their network behaviors at three different age conditions (7-days, 12-days, and 17-days old) alongside age-matched non- sleep deprived controls. We found statistical differences between sleep deprived and control groups in younger, but not older, networks across various interaction measures, which encourages further investigation into the early life neurogenetic sleep correlates that regulate the development of the social brain and behavior.

Keywords: ageing
Drosophila melanogaster
sleep
social network analysis
social networks
Advisor: Levine, Joel D
Investigating Non-invasive Saphenous Nerve Activity by various Electrode Configuration Recordings at the Ankle during Non-invasive Saphenous Nerve Stimulation

Saphenous nerve stimulation is an emerging therapy that can potentially be used as a treatment in patients with overactive bladder (OAB). One of the challenges is the inability to determine whether the nerve is electrically activated. This thesis investigated the feasibility of non-invasively recording neural activity evoked by saphenous nerve stimulation. In 16 human subjects, four different recording electrode configurations (monopolar, bipolar, tripolar, and tetrapolar) were used to measure compound nerve action potentials (CNAP) and subsequently compare the peak-to-peak amplitude of the neural signal (Vpp) produced by recording electrodes. The tetrapolar recording configurations yielded the largest Vpp that was at least twice that of the other configurations. This configuration also enabled CNAP detection at lower stimulation amplitudes compared to monopolar configurations overall and one bipolar configuration (Bi4-5). This non-invasive recording technique provides the first-in-human data that shows the feasibility of using a tetrapolar recording configuration for measuring saphenous nerve signals in humans. Further clinical study is required to assess feasibility in OAB patients.

Keywords: Compound nerve action potentials
Neuromodulation
Non-invasive stimulation
Overactive Bladder
Saphenous nerve
Tetrapolar electrode configuration
Advisor: Yoo, Paul B
Masani, Kei
Enhancement of a Collagen Membrane for Bone Regeneration

Guided Bone Regeneration (GBR) is a technique used to restore deficiencies in bone architecture that have resulted from disease, loss of function or trauma. It involves applying a barrier membrane to cover a bone defect and exclude the migration of epithelial cells and fibroblasts that would interfere with bone formation, allowing osteogenesis to occur. This exploratory study aimed to enhance the properties of a membrane through in situ induced biomineralization and cross-linking, using a commercially-available, dual-layer collagen membrane as a model: Bio-Gide®. Many of the membranes are prepared from xenogeneic collagen and differ in strength, malleability, and rates of degradation, so a consistent model is necessary. Biomineralization was promoted by the addition of amelotin and hydroxyapatite nanoparticles onto the porous side of the membrane, while cross-linking to prolong collagen degradation was done using methylglyoxal. Preliminary results were encouraging but will require further study to evaluate future clinical relevance.

Advisor: Bozec, Laurent
Aging, Cellular Senescence, and Wound Healing in a Burn Model

Despite advancements in burn care, older burn patients continue to experience the highest rates of mortality. Wound healing, a process that directly impacts burn patient survival, is impaired in older burn patients compared to their younger counterparts. Cellular senescence, a major aging hallmark, is directly involved in wound healing and represents a driver of tissue dysfunction. Notably, the senescent cell burden can be altered by pharmacological interventions, senolytics, which induce the apoptosis of senescent cells, opening avenues for potential therapies. The objective of this thesis was to investigate the presence and role of age-related senescence in the dynamic process of post-burn wound healing and explore the use of the senolytic combination Dasatinib + Quercetin (D+Q) in aged mice. We conclude that in aged burn wounds, cellular senescence is a factor in reduced skin regeneration. Accordingly, senescence-targeting drugs may be a therapeutic option to accelerate wound healing after severe burn injury.

Advisor: Hinz, Boris
Jeschke, Marc G
Machine Learning to Predict and Optimize Lower Extremity Arthroplasty Resource Utilization

Total knee and hip arthroplasty (TKA and THA, respectively) are common and resource intensive procedures contributing to significant burden on healthcare systems. The overall aim of this thesis project is to identify and develop strategies to improve elective surgical scheduling for TKA and THA. Machine learning and optimization to predict resource utilization-related outcomes such as duration of surgery and length of stay for arthroplasty patients were identified. A predict-then-optimize approach utilizing neural network models and linear programming was compared to historic scheduling strategies. Data sources for this work include the administrative National Surgical Quality Improvement Program and an institutional database from the Holland Centre at Sunnybrook Health Sciences Centre. The most important features of the neural network models for outcome prediction were identified and compared between databases. Together, these findings are the foundation upon which to develop a “smart” surgical scheduling system and improve the efficiency of operating room utilization.

Keywords: Arthroplasty
Efficiency
Machine Learning
Optimization
Scheduling
Advisor: Whyne, Cari M
Ravi, Bheeshma
Plasma Neurofilament Light Chain as a Biomarker of Global Cognition in the Early Stages of Cognitive Impairment

Neurofilament light chain (NfL) is an established biomarker of neuroaxonal injury, but further work is needed to determine its clinical utility in the early stages of cognitive impairment. The present study assessed 1) the relationship between NfL and global cognition in n=71 individuals with mild neurocognitive disorder (NCD) and 2) differences in NfL between individuals with mild NCD and n=49 age/sex-matched controls. Global cognition and plasma NfL levels were measured using the Montreal Cognitive Assessment and enzyme-linked immunosorbent assays, respectively. Plasma NfL was associated with worse global cognition at baseline (β=-0.276, p=0.032). Longitudinally, baseline plasma NfL did not predict a decline in global cognition; however, an increase in NfL was associated with worse global cognition (b[SE]=-4.81[2.06], p=0.023) over time. NfL levels did not differ in the mild NCD and control groups. Overall, these findings suggest a relationship between plasma NfL and global cognition in the early stages of cognitive impairment.

Keywords: Biomarker
Cognitive Impairment
Global Cognition
Mild Neurocognitive Disorder
Neurofilament Light Chain
Plasma
Advisor: Lanctôt, Krista
Deuterium Reclamation From C-Si Codeposits Using Thermo-oxidation

Codeposition within magnetic confinement fusion devices where plasma fuel, namely tritium, is trapped along with eroded material, poses serious economic and safety concerns for these devices. Mitigation of the build-up of carbon-based codeposits within magnetic fusion devices can be achieved by thermo-oxidation. This involves heating the codeposit films under an oxidizing atmosphere, typically oxygen. Recently, silicon carbide (SiC) has garnered attention as a candidate PFM due to its good neutron irradiation damage resistance and high operating temperatures. While a previous study has investigated the hydrogen retention within C-Si codeposit films, the removal of hydrogen from these films using thermo-oxidation has yet to be studied. It is crucial to determine if the significant non-carbon component of Si within these films will affect the removal of hydrogen as was observed with C codeposits films containing a significant fraction of Boron.

Keywords: Carbon
Codeposits
Deuterium
Fusion
Silicon Carbide
Thermo-oxidation
Advisor: Davis, James JD
Psychological Maltreatment and Retired, Competitive, Women Athletes' Conformity to Sport Ethic Norms

The sport environment has the potential to be very advantageous to one’s development and wellbeing; however, the culture of sport is plagued with excessive pressures and extreme expectations which enhances athletes’ susceptibility to experiencing harm. The purpose of this thesis was to qualitatively examine women athletes’ conformity to the sport ethic and their experiences of psychological maltreatment during their time in sport. A total of thirteen retired, competitive, women athletes from various sports participated and engaged in a one-to-two-hour semi-structured interview, which were analyzed thematically. Three major themes were generated: development of conformity to the sport ethic; cycle of conformity and psychological maltreatment; and long-term consequences of conformity. Findings are interpreted to suggest that athletes’ uncritical adherence to the sport ethic is learned through observing and modelling peers within their sport environment. As well, conformity to the sport ethic and experiences of psychological maltreatment are interrelated with one another.

Keywords: Conformity
High Performance
Psychological Maltreatment
Sport Ethic
Violence
Women Athletes
Advisor: Stirling, Ashley
The MSE Knowledge Engine

Due to the vast range of content in the undergraduate MSE curriculum, there is reason to investigate whether students are successfully encoding curriculum knowledge long-term. Studies in memory research suggest that the retention of university course content significantly declines in the months after the course is taken. This project involves the creation of a curriculum database to cultivate a strong conceptual organization of knowledge, as a way to enhance students’ retention of content. Previous research supports the use of knowledge maps and ontologies to synthesize curriculum content into an organizational road map. This paper presents an ontological framework which holds a database of approximately 2,000 second-year MSE curriculum concepts. The database is implemented in the format of a customized software platform, specific for displaying the ontology dynamically. An emphasis is placed on the user interface design, and a user experience study is performed to evaluate the final product.

Keywords: Curriculum Knowledge Map
Knowledge Mapping
Memory Retention
Ontology
Undergraduate Engineering Education
Advisor: Hibbard, Glenn