VictorJuiz/thesis huggingface dataset:
Fostering Cross-border Learning and Engagement through Study Abroad Scholarships: Lessons from Brazil's Science without Borders Program

This study examines the potential benefits of participating in the Science without Borders (Ciência sem Fronteiras - CsF) program, a study abroad scholarship program created in 2011 by the Brazilian government. Like other scholarship programs, CsF seeks to foster human capital development and the internationalization of science and technology in the country. Differently from other programs, however, CsF targets undergraduate students in the sciences. While Brazil has received positive feedback for this initiative, critics have argued that insufficient planning may hinder this program’s ability to deliver desired outcomes. Thus, through a literature review and 20 interviews with CsF scholarship recipients at the University of Toronto, this qualitative study evaluates the program’s ability to promote important benefits. Although the study identified various student benefits, the research also found structural issues that prevented all participants from benefitting equally, demonstrating the importance of collaborative planning and implementation of study abroad scholarship programs.

Keywords: Brazil
Canada
international education
international scholarship programs
international students
study abroad
Advisor: Sá, Creso
Alkaline Polymer Electrolytes for Electrochemical Capacitors

Polymer electrolytes for electrochemical capacitors in place of liquid electrolytes were developed to prevent issues such as leakage and safety concerns. Currently, there is a lack of available OH--ion conducting polymer electrolytes compared to Li+-ion and H+-ion conducting ones. OH--ion conducting polymer electrolytes with high ionic conductivity and environmental stability in ambient conditions are required. TEAOH-PVA polymer electrolyte, a suitable replacement for KOH-PVA, demonstrated similar pristine ionic conductivities and superior shelf-life in ambient conditions. TEAOH-PVA also revealed the highest ionic conductivity compared to TEAOH-PEO and TEAOH-PAA polymer electrolytes. Optimization of TEAOH-PVA via light cross-linking produced a polymer electrolyte with a high ionic conductivity of 1 x 10-2 S cm-1 and stable shelf-life over a period of 80 days. An EDLC device made with this polymer electrolyte yielded an excellent capacitance of 110 μF at 120 Hz, appropriate for high frequency filtering applications.

Keywords: alkaline
electrochemical capacitors
electrolytes
polymers
supercapacitors
Advisor: Lian, Keryn
The Anchored Separated Representation for High Dimensional Problems

Although topics in science and engineering that involve dimensions beyond x-y-z appear obscure, in truth numerous examples abound. For instance, uncertainty quantification requires approximating and integrating functions with many inputs, while the study of non-linear random vibrations involve PDEs whose dimensionality scales with the system's degrees of freedom. Such problems are numerically difficult since the application of classical mesh based techniques incur computational demands that scale exponentially with the dimension; this is the curse of dimensionality. In this thesis we formulate two tractable numerical methods that circumvent this curse by assuming sparsity in the model representation. The first method, the anchored separated representation, is a provably minimal decomposition for functions that are sparse in a multiplicative sense. The second method is an iterative extension for approximating functions that are sparse in rank. We illustrate with numerical examples the application of both methods to a broad class of high dimensional problems.

Keywords: Curse of Dimensionality
Function Decomposition
High Dimensional Problems
Sparse Approximation
Advisor: Nair, Prasanth B
Bread or Circuses? Parsing Representative and Representational Democratic Discourse on U.S. Political Blogs

This thesis finds empirical support for Jodi Dean's theory of declining symbolic efficiency through a qualitative content analysis of discourse concerning the 2013 U.S. government shutdown on political blogs. Themes of this thesis explore reflexivity, decontextualization, and an erosion of meaning brought about by changing media technologies and practices. Humanistic analyses of media and politics by scholars such as Benkler (2006) and McChesney (1999) are contrasted with works by Gitlin (1980), Postman (1985), and Dean (2010), who see media systems operating outside human control. This study's methodology relies upon Knight and Johnson's (2011) pragmatic justification for democratic institutions. The analysis uses a system of categories to describe statements about political strategy along four dimensions: operant; method of action; operand; and the consequence of the strategy. This study identifies important distinctions between textual descriptions of nominal and instrumental strategy; it is argued that nominal discourse represents the influence of symbolic inefficiency.

Keywords: blogs
democracy
discourse
identity
pragmatism
psychoanalysis
Advisor: Caraway, Brett
A Spatial Analysis of Pedestrian Injury in the City of Toronto

The City of Toronto experienced a ten-year high in pedestrian fatalities last year and has the highest pedestrian collision rate of Canadian cities. Understanding the geography of pedestrian motor vehicle collisions (PMVCs) can provide evidence to inform policy and planning targeting increased walking while reducing pedestrian injury risk. This thesis explores spatial patterns of PMVCs in the City of Toronto, with a specific focus on two particularly vulnerable road users; children and seniors. Distinct spatial patterns of PMVCs and injuries by type and age are found. This finding is further investigated by exploring the relationship between an attempt to measure equity across neighbourhoods in Toronto and pedestrian injury risk. The results suggest age- based differences in the relationship between neighbourhood equity indicators and PMVCs. A higher PMVC and injury risk for children was observed in neighbourhoods with poorer equity outcomes, while no significant relationship with equity outcomes was observed for seniors.

Keywords: Age
Pedestrian safety
Spatial Analysis
Advisor: Buliung, Ron
Evaluation of the Shaping Characteristics of ProTaper Gold, ProTaper NEXT and ProTaper Universal Systems in Curved Canals and the Analysis of Torsional Profiles of New and Used Instruments

Shaping characteristics and torsional profiles of the ProTaper Gold system (PTG) were compared with that of ProTaper NEXT (PTN) and ProTaper Universal (PTU) systems. Twenty-four mandibular first molars with 2 separate mesial canals were matched anatomically by micro-CT and prepared with rotary systems (n =16) to F2 or X2 instruments, respectively. Co-registered images were evaluated for 2- and 3-dimensional morphometric measurements. Maximum torque and angle of deflection were determined for 30 new or used PTG, PTN and PTU X2 or F2 instruments. Data was statistically compared using Kruskal-Wallis or Bonferroni/Dunn tests for post hoc and 1-way ANOVA tests (α=5%). PTG and PTN produced less transportation and % decrease in dentin thickness than PTU. PTN had less canal wall contact than PTG and PTU. PTN demonstrated the lowest maximum torque and angle of deflection at fracture and overall mean torque and angle of rotation at fracture decreased after use.

Keywords: canal transportation
micro-computed tomographic imaging
nickel-titanium instruments
root canal preparation
rotary instruments
torsional failure
Advisor: Basrani, Bettina
Re-evaluating Secondary Disinfectants as Sentinels of Contamination and Using a Systems Vulnerability Model

To build a framework in which secondary disinfectants can be quantitatively evaluated, three tasks were performed: (1) A sampling campaign was conducted at a community using an alternative secondary disinfectant (HuwaSan peroxide) to evaluate various water quality parameters; (2) bench-scale experiments examined the efficacy of different disinfectants as sentinels of contamination; and (3) a systems vulnerability assessment was performed (EPANET-MSX). The results show that: (1) HuwaSan, can limit DBP formation while maintaining acceptable water quality in terms of the parameters measured; (2) chlorine was observed to be the most appropriate sentinel of intrusion under the tested conditions; and (3) under modeled conditions, E. coli propagation was controlled by all tested disinfectants. For Giardia intrusions, Cl2, ClO2, and HSP achieved 3-log inactivation between 30-150 minutes, although an assumed inactivation rate for HSP was used. The same inactivation required chloramines and H2O2 between 330-1180 and 170-910 minutes, respectively.

Keywords: Distribution System
Drinking Water
Secondary Disinfectants
Secondary Disinfection
Advisor: Hofmann, Ron
Examining the Function of β-catenin at Adherens Junctions during Dorsal Closure and the Formation of the Ventral Epidermis in Drosophila

Adherens junctions (AJs) consist of Cadherin-Catenin Complexes (CCCs); each CCC contains DE-cadherin, p120catenin, β-catenin (Armadillo in Drosophila) and α-Catenin. The question addressed here was whether β-catenin functions primarily to physically link DE-cadherin to α-Catenin or it has additional regulatory function in AJ stability. Dorsal closure (DC) defects in cadherin-deficient embryos are partially rescued by fusion proteins that directly link DE-cadherin to α-Catenin without recruiting Armadillo/β-catenin to AJs. This suggests that Armadillo at AJs is important for DC apart from being a linker. However, ventral defects were completely rescued by the same chimeras, indicating that Armadillo/β-catenin has no essential regulatory function at AJs in the ventral epidermis. Lastly, DC defects in Armadillo/β-catenin-deficient embryos were only partially rescued by the expression of DE-cadherin α-Catenin chimeras perhaps due to compromised Wnt signalling. Therefore, Armadillo/β-catenin has a general essential function in linking DE-cadherin to α-Catenin but a tissue-specific role in controlling AJ dynamics.

Keywords: Adherens junctions
Armadillo
Cadherin-catenin complex
Dorsal closure
Advisor: Tepass, Ulrich
The Formulation of a Comprehensive Strategy for Computed Tomography Radiation Dose Optimization in Ontario

As the awareness for the cancer risks associated with diagnostic computed tomography (CT) exams rise, countries and institutions have begun to prioritize dose optimization. Currently, Ontario’s only regulation for CT operation does not address dose management. This study aimed to develop an achievable and comprehensive model for CT dose management regulations in Ontario. A relationship analysis of evaluation results from the Regulatory Assessment for CT (RACT 2) and dose level comparisons was performed to elicit factors that are predictive of highly effective regulations. Qualitative interviews with jurisdictional representatives, radiologists and medical physicists extracted the facilitators and barriers to uptake of CT regulations. Ontario’s model contained minimum requirements to initiate dose management efforts, and four possible dose optimization specific approaches, which are diagnostic reference levels, compliance monitoring, peer-review process and radiation protection committee. It is recommended that at least one specific approach be adopted by Ontario’s new CT dose management regulations.

Keywords: Computed tomography (CT)
policy development
policy evaluation
radiation dose management
radiation dose optimization
Advisor: Easty, Anthony C
Ruthenium-Diazafluorenide Complexes for Catalysis of Oxa-Michael Addition Reactions

Recent studies in the field of organometallic catalysis have explored metal-ligand cooperativity in the catalysis of oxa-Michael addition reactions. The ligand-based reactivity of ruthenium-diazafluorenide complexes for the activation of small molecules has previously been reported in our group. This thesis presents an exploration into the catalytic potential of these complexes for oxa-Michael addition reactions. Herein, we reveal an efficient ruthenium-diazafluorenide system which catalyzes the hydroalkoxylation of α,β-unsaturated nitriles, followed by an analysis of the reactivity, conditions, and substrate scope of the catalyst system.

Advisor: Song, Datong
Glypican-1 Modulates CSPG inhibition on Growing Axons

During development, guidance cues mediate axon guidance such that synaptic connections made give rise to a properly functioning central nervous system. Chondroitin sulfate proteoglycans (CSPGs) inhibit axon outgrowth by interacting with their transmembrane receptor protein tyrosine phosphatase sigma (RPTPσ). Glypicans (GPCs) also interact with RPTPσ via their heparin sulfate glycosaminoglycans. Due to their GPI-anchor, GPCs are present in the lipid raft region of the membrane. Here it is shown that in retinal explants cultured on CSPGs treated with methyl beta cyclodextrin (MβCD), axon outgrowth is promoted, implying that RPTPσ may be associated with the lipid raft region to mediate the effect of CSPGs. When either exogenous GPCs are added or endogenous GPCs are silenced, there is a significant rescue in axon outgrowth on CSPGs. This suggests that GPCs may play a role in recruiting RPTPσ into the lipid raft region of the membrane to mediate the inhibitory effect of CSPGs.

Advisor: Monnier, Philippe
A Spiking Circuit Model of Sequence Learning

The ability to integrate information over time is fundamental to cognition. Any sensory experience, from object recognition to speech comprehension, utilizes this ability. Contrary to traditional models in which memory and perception are supported by separate circuits, recent work has demonstrated perceptual circuits can integrate information over time, as their response to an input at one moment may depend on what happened seconds earlier. We implemented a spiking model utilizing spike-timing dependent synaptic plasticity in a localized visual cortical circuit to investigate how sensory circuits are able to integrate information over time. We demonstrate that a lengthening circuit memory develops as a result of repeated exposure to a stimulus and that repeated exposure also leads to stronger synapses between neurons processing the input as well as associating sequential stimuli.

Keywords: model
plasticity
process memory
sequence learning
spiking
STDP
Advisor: Honey, Christopher J
Characterization of Novel Glucagon Receptor Interactors that Modify Receptor Activity

Glucagon helps maintain blood glucose homeostasis by stimulating gluconeogenesis and glycogenolysis. Elevated glucagon levels have been reported in type 2 diabetics, and may be in part responsible for their abnormally high blood glucose. A comprehensive understanding of glucagon receptor regulators is currently unavailable. Members of my lab performed a mass spectrometry screen to detect glucagon receptor interactors, 5 of which were validated to be true interactors by co-immunoprecipitation and Western blotting. The project outlined in this thesis began with the functional characterization of these interactors. Two interactors, low-density lipoprotein receptor (LDLR) and transmembrane emp24 domain trafficking protein 2 (TMED2) significantly enhanced glucagon stimulated glucose production, while tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein, beta (YWHAB) lowered glucagon stimulated glucose production in primary hepatocytes. Because of YWHAB’s ability to lower glucose production, the underlying mechanism was explored and evidence suggests YWHAB enhances endocytosis of the glucagon receptor into the cell following glucagon stimulation.

Keywords: Glucagon receptor
Glucose production
Hepatocytes
Interactome
Membrane proteins
Advisor: Wheeler, Michael B
The Anatomic Connectome and Functional Dissection of the Caenorhabditis elegans First-stage Larvae (L1) Motor Circuit

During development, neural networks exhibits anatomic and functional modifications yet the activity patterns change remains poorly understood. The neural circuit controlling locomotion of C. elegans undergoes major reconstructions at the end of first-larval (L1) stage. In adults, the ventral/dorsal body wall muscles are symmetrically innervated by cholinergic and GABAergic motor neurons (MNs). Cholinergic MNs innervating ventral muscles are not derived during early L1 stage, yet the animals can still generate undulation. This study addressed how L1 C. elegans produces undulation and the mechanism underlying muscle innervations. We demonstrated that the activities of dorsal cholinergic MNs are required for both dorsal and ventral muscle contraction, and the GABAergic MNs mediate only ventral muscle relaxation. This indicated a differential synaptic wiring between MNs and muscles in L1 to permit undulation. Through this comparative analysis between juvenile and adult locomotion, we hope to provide insights on principles of behavioral adaptation during sensorimotor development.

Keywords: calcium imaging
c elegans
development
locomotion
Advisor: Zhen, Mei
Polyelectrolyte Multilayers: an Investigation into their Assembly and Behavior with Diffraction Based Sensing

A diffraction based sensing set-up was evaluated for use in monitoring the assembly of polyelectrolyte multilayers (PEMs). PEMs are thin films assembled via the layer-by-layer method, which consists of exposing a substrate to polyanions and polycations in sequence. Understanding the fundamental behavior of PEMs is instrumental to designing their properties to fulfill unique functions. In this work, diffraction based sensing is explored as a method to monitor the build-up of multilayers. The initial polymer layer is printed as a diffraction grating pattern and the PEM is assembled on top resulting in a change in height of the grating. This change in height can be monitored by the change in intensity of the diffracted spots. To demonstrate diffraction sensing is sensitive to PEM assembly, experiments testing its response to salt concentration, polymer concentration, and post assembly processing were carried out.

Keywords: diffraction
diffraction sensing
polyelectrolyte multilayer
Advisor: Goh, M C
Characterization of the Immune Basis for Reduced IFN-α in Serologically Active Clinically Quiescent SLE Patients

Serologically active clinically quiescent (SACQ) patients with systemic lupus erythematosus (SLE) are clinically quiescent despite the presence of autoantibodies. SACQ patients differ from serologically active clinically active (SACA) patients in terms of decreased levels of IFN-α and IFN signature. Given the role of IFN-α in SLE, we sought to determine the mechanisms underlying the lack of type I IFN elevation in SACQ patients. In assays containing peripheral blood mononuclear cells and nuclear extracts, SACQ serum induced decreased levels of IFN-α compared to SACA serum. Mixing experiments revealed that there are factors in SACQ serum that inhibit IFN-α production. The presence of anti-IFN-α antibodies was found in a small proportion of SLE patients and correlated with the ability to block IFN-α in-vitro but not with a decreased IFN signature in-vivo or clinical activity. These results suggest that SACQ patients have multiple mechanisms that lead to their decreased type I IFN production.

Keywords: Interferon
SACQ
SLE
Advisor: Wither, Joan E
Deficiency of Myelin Proteins during Brain Development in Fragile X Mice

Fragile X syndrome (FXS) is the most common inherited form of mental impairment and the leading genetic cause of autism. Our laboratory has previously reported that myelination is delayed in the cerebellum of a mouse model of FXS. In my study, I assessed the spatial and temporal aspects of this myelination defect and found that the defect occurs throughout the brain in the early developing fragile X mouse. Additionally, I also examined the levels of epidermal growth factor receptor (EGFR) and two of its ligands but found little to no deficiencies in the fragile X brain. However, epidermal growth factor (EGF) levels in the plasma and thyroid of adult fragile X mouse were found to be significantly reduced. Lastly, the fragile X mice were treated with intranasal heparin binding EGF-like growth factor (HB-EGF) in an attempt to rescue the myelination defect but the treatment did not promote early postnatal myelination.

Keywords: Autism
Epidermal growth factor
Epidermal growth factor receptor
Fragile X Syndrome
Myelination
Myelin basic protein
Advisor: Hampson, David R
Driving under Involuntary and Voluntary Distraction: Individual Differences and Effects on Driving Performance

Distracted driving compromises safety. Distractions stem from intentional engagement in secondary tasks (voluntary) or an inability to supress non-driving related information (involuntary). This thesis aims to understand, through two driving simulator experiments, how involuntary and voluntary distraction affect drivers and individual differences in susceptibility to either type of distraction. Findings show involuntary and voluntary distraction degrade driving performance. Drivers appear more cognisant of voluntary distractions compared to involuntary distraction. They compensate for their accelerator release delays in response to lead vehicle braking by transitioning more quickly to the brake pedal under voluntary distraction, but not under involuntary distraction. Drivers self-reporting frequent distraction engagement in real-world driving glanced more frequently at the voluntary distraction task used in the experiments and drivers self-reporting greater everyday distractibility had longer glances toward involuntary distraction stimuli. Involuntary distraction engagement was not related to the manipulated environmental visual complexity nor inhibition ability measured through cognitive tasks.

Keywords: Driver Distraction
Driving Simulator
Human Factors
Involuntary Distraction
Load Theory
Voluntary Distraction
Advisor: Donmez, Birsen
Measuring the Young's Moduli of Sugar Cross-linked Native Type I Collagen Fibrils

Collagen is the most important structural protein in the human body, providing tissues with increased structural rigidity and elasticity. Through ageing, collagen-containing tissues such as the myocardium stiffen. This gradual loss in tissue elasticity can lead to pathogenesis, and can further be expedited through diabetes mellitus. This stiffening may be attributed to collagen cross-linking initiated through prolonged exposure to reducing sugars in blood. Atomic force microscopy (AFM) was employed to image native collagen fibrils, and measure their reduced Young’s moduli via nanoindentation, to quantify the impact of sugar-induced cross- linking. Comparing control and D-ribose-incubated (sample) fibrils revealed a statistically significant difference between their average reduced moduli, which was observed in collagen fibrils exposed to glutaraldehyde, a standard biological cross-linker. D-ribose-induced cross-linking was verified by sample fibrils displaying resistance to acid degradation via monitoring their turbidity. These experimental findings revealed an increase in collagen fibril stiffness due to D-ribose-induced cross-linking.

Keywords: Atomic force microscopy
Collagen
Cross-link
Fibril
Nanoindentation
Sugar
Advisor: Goh, M. Cynthia