VictorJuiz/thesis huggingface dataset:
3D Hydrogels for Astrocyte/Neural Progenitor Cell Co-cultures

This thesis explores the use of hyaluronic acid-based hydrogels as extracellular matrix mimics for growing astrocytes and neural progenitor cells in 3D. An examination of laminin- and fibronectin-based peptides showed that modifying gels with peptides containing the adhesive sequence RGD provided the best attachment for astrocytes. Both Diels-Alder and oxime "click" reactions were examined as gelation mechanisms, and oxime-crosslinked gels were used for cell co-cultures. It was determined that astrocytes grown on tissue culture plastic underneath the gels supported neural progenitor cell growth and differentiation better than 3D encapsulated co-cultures. These results demonstrate the importance of co-culture conditions to examine the role of astrocytes on neural progenitor cell fate. Ultimately, engineered matrices, such as those described herein, may provide useful biomimetic environments in which to probe development and/or disease progression in vitro.

Keywords: astrocyte
cell encapsulation
hydrogel
neural progenitor cell
Advisor: Shoichet, Molly S
Seismic Performance of New Hybrid Ductile-rocking Braced Frame System

A new hybrid ductile-rocking (HDR) seismic-resistant system is proposed which consists of a code-designed buckling-restrained braced frame (BRBF) that is free to rock on its foundation. The goal of this system is to reduce the disadvantages associated with BRBFs, such as excessive drift concentrations and residual deformations, while maintaining their reliable limit on forces and accelerations. A lockup device ensures the full code-compliant strength at a predetermined column uplift, and supplemental energy dissipation elements reduce the overall response. Buildings of 2, 4, and 6-storeys in height were designed for Los Angeles, California, and studies were performed to investigate how the energy dissipation strength, lockup base rotation, and vertical mass modelling choices affected the system's performance and dynamic response. An example detail was developed that included a cast steel energy dissipating device. These studies showed that the HDR system achieved a significant reduction in brace damage over conventional BRBF structures.

Keywords: base rocking
buckling-restrained brace
earthquake
energy dissipation
seismic resilience
self-centering
Advisor: Christopoulos, Constantin
Non-isothermal Two-phase Transport in the Polymer Electrolyte Membrane Fuel Cell Microporous Layer

This thesis investigates the water transport mechanisms in the crack-free microporous layer (MPL) of a polymer electrolyte membrane (PEM) fuel cell. Synchrotron X-ray radiography was used to visualize and quantify the in situ liquid water in the gas diffusion layers (GDLs) of an operating fuel cell. A methodology was developed to correct the artefact of imaging sample movement. Furthermore, to address inaccuracies due to the scattering effect and higher harmonics at the synchrotron beamline, a calibration technique was introduced in order to experimentally determine the liquid water X-ray attenuation coefficient. Through in situ radiography, liquid water breakthrough events were observed in the MPL, and measured water thicknesses were used as inputs into a one-dimensional (1D) heat and mass transport model. The 1D model was used to describe the coupled relationship between liquid and vapour transport through the cathode MPL and the temperature distributions in the operating fuel cell.

Keywords: gas diffusion layer
microporous layer
polymer electrolyte membrane fuel cells
synchrotron radiography
two-phase transport
Advisor: Bazylak, Aimy
The Speculative Temporalities of Landholding: Past, Present, and Future

This three-part dissertation explores the roles and implications of time in landholding. Paper A sets the theoretical stage by exploring how temporal symbolism is used to construct land as an object of enduring value in sedentary societies, arguing that sedentary landholding is governed in temporal, not just spatial, terms. Paper B engages more specifically with the contemporary idealisation of land as a commodity, extending the observations of Paper A to challenge the commodification and speculative private appropriation of land’s future ‘benefit streams’. Here, I suggest a more inclusive definition of land value as a potential tool to reveal certain shortcomings of market-led land policies. Finally, in Paper C, I present a case study of the non-market land policies undertaken in the five Asian ‘Tiger’ countries after WWII; I argue that these countries substantially reversed the paradigm described in Paper B by channelling the ‘benefit streams’ of landholding towards social stability.

Keywords: Commodification
Land
Landholding
Land tenure
Speculation
Temporality
Advisor: Kepe, Thembela
Effectiveness of a Community-based After-school Substance Use Prevention Program: The Kiwanis Boys and Girls Clubs- The Level Up! Program

Introduction: I evaluated a community based after school substance prevention program for youth out of the Kiwanis Boys and Girls Club located in Toronto. The examination of four key skills was conducted: peer mentorship, leadership, community connectedness, and knowledge to conduct an evaluation of the program. Design and methods: Using secondary data provided by Health Canada, a small-scale (n=16) quantitative analysis was done to compare pre and post-tests. An observational site visit was conducted as part of a qualitative analysis to triangulate the data collected from the tests. Results: The tests and observations show some significant differences in some aspects of the skill development. The data analysis was inconclusive: there is no evidence that the program has significantly positive effects on skill development for substance prevention. Conclusions: Underprivileged communities require the development of more programs to aid youth in developing skills that will prevent deviant behavior, especially substance use and abuse.

Advisor: Davies, Scott
Association of Human Leukocyte Antigen-G Polymorphisms and Clinical Outcomes Post-transplantation

Human leukocyte antigen (HLA)-G has been shown to inhibit cardiac cells injury in vitro, suggestive of protection against cardiac allograft vasculopathy (CAV). The expression of HLA-G is regulated by single nucleotide polymorphisms (SNPs), and their association with CAV remains unknown. The objective was to determine the association between donor and recipient genotypes and diagnosis of CAV. We retrospectively analyzed 251 heart recipients of whom 196 had their corresponding donors and the association was evaluated with parametric hazard regression models. At 10 years after transplantation, freedom from severe CAV, retransplantation or death was 64% over a mean follow-up of 5.2 ± 3.6 years. In multivariable analysis, the presence of donor-recipient SNP -201 (CC-CC) matching was associated with an increased risk of severe CAV. This is the first investigation to identify an association and it may reveal a pathway to be explored for potential diagnostic and therapeutic strategies for CAV.

Keywords: Cardiac allograft vasculopathy
Heart Transplantation
HLA-G
Polymorphisms
Advisor: Rao, Vivek
Mental Health Support for Newcomer Youth: Fostering Resilience and Compassion among Refugees and their Peers

Refugee youth represent one of the fastest growing segments of the Canadian population. Upon resettlement, post-migration factors can have severe impacts on mental health and wellbeing. In Ontario, schools are relied upon to support integration and manage the reception of newcomers, yet children continue to face struggles that impede upon wellbeing. Social exclusion, discrimination, and a lack of social support are amongst these issues. A postmodern framework is employed to explore the social, historical, and political implications of the refugee experience within the Ontario public school context. A hermeneutic approach is used to interpret curriculum documents, policies, policy guidelines, and other texts that shape the Ontario elementary education system. Based on my research, I propose that a holistic, mindfulness based curriculum be integrated into Ontario education in order to enhance resilience among refugee youth while fostering compassion and support among their peers.

Keywords: education
hermeneutics
mental health
mindfulness
qualitative research
refugee
Advisor: Cooper, Karyn
Tryptophan Requirements in School Age Children Determined by the Indicator Amino Acid Oxidation Method; Preliminary Results

Background: The Indicator Amino Acid Oxidation (IAAO) technique has shown that amino acids requirements are underestimated. The current tryptophan requirements for healthy school age children are based on factorial method and have never been re-evaluated using IAAO. Objective: To determine tryptophan requirements in healthy school age children by measuring the oxidation of L-[1-13C]phenylalanine to 13CO2 in response to graded intakes of tryptophan. Design: Three healthy school age children participated in 14 study days. Each study day had a different tryptophan intake. Stable isotopes were used as tracer to determine the oxidation level. Breath and urine samples were taken to compare the oxidation level.. Conclusion: With our current data, we were not able to define tryptophan requirements in healthy school age children using the IAAO method. However, we observed a decrease in L-[1-13C]phenylalanine oxidation level in relation to increase intake of tryptophan.

Keywords: amino acids
Indicator
oxidation
Tryptophan
Advisor: Tomlinson, Christopher
Characterization of Two Small RNAs of Streptococcus mutans UA159

Small RNAs (sRNA) regulate several processes including metalloregulation, acid-tolerance, biofilm formation, and virulence. Streptococcus mutans UA159 is an etiological agent of dental caries. Several sRNAs were found in intergenic regions of S. mutans and two were characterized. The first characterized sRNA, SurC, was located within the loci between dnaK and dnaJ (~190 nucleotides) and was developmentally regulated. The second characterized sRNA, MrrC (~420 nucleotides), a metal responsive RNA was located between pyrG and fbaA. In THYE, there was no change observed in growth rate for either ΔSurC and ΔMrrC. In chemically defined medium, the growth rate of ΔMrrC was significantly reduced at pH 5.0 and in 4.0% ethanol. Both ΔSurC and ΔMrrC contain defects in biofilm formation, acid tolerance response, and transformation frequency. Identification of sRNAs and understanding their function within S. mutans is necessary to provide insight into the molecular control of virulence for this caries forming organism.

Keywords: acid tolerance
biofilm formation
metalloregulation
small RNA
Streptococcus mutans
transformation
Advisor: Cvitkovitch, Dennis G
Hair Segmentation using Heuristically-trained Neural Networks

We present a method for binary classification using neural networks that performs training and classification on the same data using the help of a pre-training heuristic classifier. The heuristic classifier is initially used to segment data into three clusters of high confidence positives, high confidence negatives, and low confidence sets. The high confidence sets are used to train a neural network (NN) which is then used to classify the low confidence set. Applying this method to the binary classification of hair vs. non-hair patches, we obtain a 9% performance increase using the heuristically-trained NN over the current state of the art hair segmentation method.

Keywords: hair segmentation
machine learning
neural networks
Advisor: Aarabi, Parham
Low-swing Signaling for FPGA Interconnect Power Reduction

FPGAs are widely used in digital circuits implementation because of their lower non-recurring engineering cost and shorter time-to-market in comparison with ASICs. However, there are still area, performance, and energy efficiency gaps between FPGAs and ASICs. In this work, we propose a new FPGA architecture to narrow the energy efficiency gap. Since more than 60% of FPGA power is consumed in its interconnect, we focus on the global interconnect power reduction using low-swing signaling technique. To implement low-swing signaling, high-to-low and low-to-high voltage level converters are added to the basic architecture which consists of clusters with ten 6-input LUTs and uses single driver directional routing scheme. Simulation results on 20 largest MCNC circuits and 19 computational benchmarks confirm that the pro-posed architecture achieves an average of 13.5% total power reduction with the cost of less than 1% area and delay overhead.

Keywords: FPGA
Interconnect
low-swing signaling
Power
Advisor: Sheikholeslami, Ali
Ghanaian Indigenous Health Practises: The Use of Herbs

Herbal medicines remain integral part of indigenous health care system in Ghana. Most conventional health medicines are directly or indirectly derived from plants or herbs. Despite its significant role in modern medicine indigenous herbal practices has been on the low light for some time due to perceived antagonistic relationship that exists between practitioners of herbal medicine and their counterpart in the conventional system. Using an indigenous knowledge discursive framework, the thesis examined the relevance of herbal medicine to the contemporary Ghanaian society. The thesis also examined the tension between the indigenous herbal practitioners and their orthodox counterparts. The thesis noted that for health care system in Ghana to be effective, there is a need for collaborate relations between these two practitioners. Also, it was noted that for health care system to be effective in Ghana, spirituality has to be central in the works of the herbal practitioners.

Keywords: Ghana
Herbal Medicine
Indigenous Medicine
Traditional Medicine
Alternative Medicine
African Medicine
Orthodox and Traditional Medicine
Spirituality
Ghanaian Spirituality
Traditional Healing
Mampong Center for scientific research into plant medicine
Herbal healing
Advisor: Wane, Njoki
Cadherin-11 Mediated Macrophage Adhesion Promotes Myofibroblast Persistence

Chronic pulmonary fibrosis is characterized by the co-existence of macrophages, which produce pro-fibrotic transforming growth factor beta-1 (TGF-β1) and myofibroblasts, which excessively secrete and contract extracellular matrix in response to TGF-β1. We propose that binding of macrophages to myofibroblasts via cadherin-11- mediated adherens junctions establishes a ‘TGF-β1 niche’ that contributes to both cells persisting in fibrosis. To test this hypothesis, we analyzed differently polarized macrophages for TGF-β1 production (fibrotic potential) and cadherin-11 expression (adhesion potential). Adhesion assays demonstrates that pro-fibrotic macrophages have a higher binding affinity for myofibroblasts than for fibroblasts. We identified the adherens junction protein cadherin-11 as a novel mediator of macrophage-to-myofibroblast attachment. Immunofluorescence of co-cultures demonstrated accumulation of cadherin- 11 in junctions between macrophages and myofibroblasts. Direct co-culture of macrophages and fibroblasts increased active TGF-β1 production compared to segregated cultures. We conclude that cadherin-11 junctions keep macrophages and myofibroblasts in close proximity to generate a microenvironment that is rich in active TGF-β1.

Keywords: Macrophage
Fibrosis
TGF-B
Advisor: Hinz, Boris
The Impact of Follicular Fluid on Oviductal Epithelial Cell Gene Expression

Recent evidence indicates high-grade serous ovarian cancer originates from the fallopian tube epithelium (FTE). Risk factors include germline mutations in breast cancer susceptibility genes, BRCA1 and BRCA2, and increased lifetime ovulatory events. Repeated exposure of the FTE to follicular fluid may contribute to early pathogenesis through repeated exposure to an inflammatory environment, which may be prolonged in BRCA mutation carriers. In partial support of this hypothesis, exposure of cultured bovine oviductal epithelial cells to follicular fluid altered expression of eight inflammation-associated genes examined. Preliminary analysis of whole genome gene expression profiling of cultured human FTE cells derived from control, BRCA1 and BRCA2 mutation carriers indicate that BRCA mutation status impacts response to follicular fluid. Differences in gene expression due to BRCA mutation status alone were also noted. These findings indicate that tubal epithelial cells respond to follicular fluid with altered gene expression that is affected by BRCA mutation status.

Keywords: Ovarian Cancer
Oviduct
Fallopian Tube
BRCA1
Ovulation
Follicular Fluid
Bovine
Primary Cell Culture
Advisor: Brown, Dr. Theodore J.
Recombinant IL-4 Injection into the Brain Alters the Inflammatory Response and Grey Matter Injury in a Rat Model of Iischemic Stroke

Following stroke, there is an inflammatory response involving activation of CNS-resident microglia, and infiltration of peripheral immune cells. This response can last for hours to days, making it more amenable to treatment. CNS-resident microglia can exist in several activation states, and in vitro, their alternative activation can be induced by the cytokine, IL-4. Here, I modeled transient focal ischemia by injecting the vasoconstrictor peptide, endothelin-1 (ET-1), into the rat striatum, either alone (untreated) or with 500 ng of recombinant IL-4 (treated). Gene expression analysis revealed a significant increase in the alternative activation markers, IL-4rα, ARG1, CD163 and CCL22; and in the IL-4 signaling molecules, STAT6 and PPARγ. IL-4 treatment increased the number of phagocytic neutrophils and degenerating neurons in the ischemic core, but did not alter the number of microglia/macrophages or the extent of whitematter injury. Thus, IL-4 might be harmful when administered at the onset of ischemia.

Keywords: Interleukin-4
Ischemia
Inflammation
Microglia
Macrophages
Neutrophils
Advisor: Schlichter, Lyanne
Effect of Oxygen on Multidrug Resistance in Term Human Placenta

The placenta contains efflux transporters, including P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP), that limit the passage of xenobiotics and certain hormones from the maternal to the fetal circulation. The expression of these transporters changes with gestational age, yet the mechanism(s) regulating this change in expression remains unknown. However, the changes in P-gp and BCRP transporter expression coincide with changes in oxygen tension in the placenta and studies in other tissues have shown that oxygen tension regulates P-gp and BCRP expression. Here, we investigate the effects of oxygen tension on P-gp and BCRP expression in the term human placenta. We demonstrate that the expression of placental P-gp is regulated by oxygen tension, which suggests that changes in oxygenation of the placenta in the third trimester have the potential to alter fetal drug exposure.

Keywords: Placenta
Drug transporters
Advisor: Matthews, Stephen
Development of a Head-up Display System for Automotive Applications Using A Repulsive-force Electrostatic Actuated Micromirror

This thesis focuses on developing a comprehensive HUD system for automotive applications based on the laser-scanning display (LSD) utilizing a repulsive-force electrostatic actuated micromirror. Key system components of the automotive HUD system are: the micromirror, the optical array, and the optical film. The current micromirror design is reinforced to better perform under driving conditions without compromising the structural durability. The optical array is developed for enhancing the magnification and the resolution of the LSD virtual and real images. The optical film is designed to reflect the LSD virtual image and diffuse the LSD real image without hindering the driving field of view. Two real-time control methods are introduced and a flickering static image is achieved at 32 fps by the time variable control method. The HUD prototype successfully displays both of the LSD virtual image (10 cm x 10 cm formed at 3.30 m away from the driver) and the LSD real image (8 cm x 8 cm formed on the windshield).

Keywords: HUD
Head-Up Display
MEMS
Micromirror
Advisor: Mrad, Ridha Ben
Chronic Pain, Opioids and Ovarian Hormones

Sex differences in pain perception have led researchers to hypothesize that ovarian hormones might mediate these differences. The animal and human literature demonstrates that ovarian hormones modulate pain and its treatments in female rodents as well as women in their reproductive years. While rife with inconsistencies in study design, the general agreement of the clinical literature raises the question as to whether this sex difference and role of ovarian hormones is taken into account in clinical practice. A chart review of 254 patient records of a specialist pain clinic in a large Canadian city revealed sex differences in types of chronic non-cancer pain (CNCP) conditions, treatments, and in sheer numbers of patients. The majority of patients were women in their reproductive years and many had co-occurring pelvic pain. Interestingly, women’s charts included no information on ovarian hormones or phase of the menstrual cycle suggesting that ovarian hormones are an overlooked aspect of CNCP treatment.

Keywords: chronic pain
sex differences
Advisor: Einstein, Gillian
Using Otoliths to Evaluate a Novel Measuring Technique, Identify Spawning Years, and Compare Somatic Growth Patterns in Lake Trout, Salvelinus namaycush

I evaluated a novel, simple-to-use, efficient method to estimate age and examine reproductive history of lake trout, Salvelinus namaycush, using sagittal otolith sections. Age estimations were made using a novel otolith section measuring technique that uses a series of parallel lines and approximates the difficult to locate nucleus with a straight line. Previous measuring techniques used straight lines or a segmented line to measure from nucleus to edge. Reproductive history was examined by investigating the prevalence of post-maturation checks; I provide evidence that these are good indicators of spawning. Additionally, mature females were significantly more likely to skip spawning than mature males (p=0.0375). Additionally, I compared the growth trajectories of mature tagged fish to mature free-living fish and did not find a statistically significant effect of tagging on the growth of either sex (male: F1=2.783, N1=61, N2=108, p=0.0967; female: F1=0.129, N1=79, N2=64, p>0.05).

Keywords: otolith
lake trout
otolith measurement
'spawning' check
somatic growth
tagging effects
von Bertalanffy
Advisor: Shuter, Brian
Socio-demographic Factors Related to Nutritional Intake and Adherence to Expert Recommendations in a Cohort of very Low Birth Weight Infants

This study investigated how post-discharge feeding practices of very low birth weight infants aligned with recommendations and explored maternal socio-demographics related to these practices. Demographics were obtained at birth. Feeding practices were collected monthly to 6 months corrected age (CA). At 4 and 6 months CA, rates of partial (36%, 29%) and exclusive (17%, 5%) breastmilk feeding were low. Vitamin D supplementation was high among infants receiving breastmilk. Recommendations for introducing solids and iron supplementation were adhered to by 45% and 55%, respectively. Overall, 8% were adhering to all feeding recommendations. Mothers with undergraduate or postgraduate degrees were more likely to provide breastmilk; mothers of Middle Eastern/South Asian ethnicity were less likely. Mothers introducing solids between 4-6 months CA had college or undergraduate education. Overall, adherence to feeding recommendations was low. Strategies to support both breastfeeding and at-risk mothers are warranted.

Keywords: preterm infant
breastfeeding
very low birth weight infant
feeding practices
maternal characteristics
Advisor: O'Connor, Deborah