VictorJuiz/thesis huggingface dataset:
Effect of Vitamin D Deficiency on Autophagy in the Intestine via MicroRNA Regulation
Keywords: Autophagy
Epigenetics
Inflammatory Bowel Disease
MicroRNA
Vitamin D

Rates of IBD have increased drastically over the past decade, greatest in children, asserting a role for the environment in disease pathogenesis. Emerging evidence has shown that vitamin D deficiency can affect the autophagy pathway and disrupt intestinal homeostasis, contributing to IBD. Epigenetic regulation through miRNAs may be a mechanism connecting vitamin D deficiency to dysregulated autophagy in IBD. Our study characterizes in the intestine the effect of vitamin D deficiency on autophagy via regulation by the miRNA, miR-142-3p. This research builds on data indicating miR-142-3p regulation of autophagy gene ATG16L1 and miR-142-3p overexpression in the intestine of IBD patients. Here, we demonstrate that vitamin D deficiency causes decreased ATG16L1 protein expression in the intestine. This poses a potential mechanism by which the environment interacts with genetics leading to IBD.
Acidic Ferric Sulphate Leaching of Pyrrhotite Tailings at 55-80 째C and at Constant Redox Potential
Keywords: Hydrometallurgy
Nickel
Pyrrhotite
Tailings

The kinetics of nickel leaching and elemental sulphur formation from pyrrhotite tailings leached with ferric sulphate at 55-80 °C was investigated at constant oxidation-reduction potential (ORP). The tailings samples originated from Glencore’s Strathcona Mill in Sudbury, ON, Canada. Potassium permanganate was used to maintain a constant ORP. The shrinking core model (SCM) was used in conjunction with the particle size distribution (PSD) to determine the controlling reaction mechanism and quantify the leaching kinetics. In contrast to previous studies, accounting for the PSD helped identify that the rate-limiting step of the process was the rate of chemical reaction on the particle surface. A reaction order of 0.43 ± 0.08 with respect to ferric ion, and -0.18 ± 0.02 with respect to ferrous ion was found, along with an activation energy of 32.7 ± 0.2 kJ/mol. Additionally, elemental sulphur yield increased with increasing temperature.
Gaseous and Particulate Matter Emissions of a Supercharged Spark Ignited Hydrogen Fueled Internal Combustion Engine
Keywords: Combustion
Engine
Hydrogen
NOx
Particulate Matter
Supercharged

A spark ignited hydrogen fueled engine was operated at three equivalence ratios (0.4, 0.5, and 0.6) with a supercharger. During steady-state road load conditions, the engine produced exceptionally low unburned hydrocarbon, carbon monoxide, carbon dioxide, and particulate matter emissions. The oxides of nitrogen (NOx) emissions of the supercharged engine were 31.4, 149.5, and 787.0 mg*NOx/km for the equivalence ratios 0.4, 0.5, and 0.6 respectively. Given that the current EPA regulations are 99.4 mg*NOx/km, this engine configuration represents a possible replacement option for gasoline fueled engines without the need for exhaust aftertreatment. During engine start-up, some of the supercharged tests exhibited particulate matter emission spikes. These particulate matter spikes do not seem to be related to equivalence ratio, coolant temperature, testing order, or start-up acceleration. Currently, there is no explanation why some of the tests produced particulate matter during engine start-up and others did not.
Normothermic Ex Vivo Kidney Perfusion - A Novel Approach for the Storage, Assessment, and Repair of Renal Grafts
Keywords: Graft Assessment and Repair
Hypothermic Preservation
Kidney Preservation
Kidney Transplantation
Normothermic Ex Vivo Kidney Perfusion
Organ Shortage

Kidney transplantation is the treatment of choice for patients with end-stage renal disease. A major problem is the worldwide severe graft shortage, which triggered interest in kidneys recovered from extended criteria donors (ECD) and donation after circulatory death (DCD). Currently utilized techniques of hypothermic preservation induce injury, especially in ECD and DCD grafts. This study investigates the feasibility and safety to preserve kidneys under normothermic, more physiologic conditions ex vivo. In a porcine model, kidneys were recovered, and preserved on ice or with â Normothermic Ex Vivo Kidney Perfusion (NEVKP)â . Kidneys preserved at normothermia providing physiologic flow, oxygen, and nutrition, demonstrated high metabolic activity and excellent graft viability during storage. Following autotransplantation, superior renal function with lower serum creatinine, higher creatinine clearance, and lower renal injury markers was demonstrated when compared to cold storage. This data suggests that NEVKP offers superior storage and provides a platform for further graft assessment and repair.
Production of Bulk Metallic Glasses for Use in Airborne Gravity Gradiometry
Keywords: Airborne Gravity Gradiometry
Arc Melting and Suction Casting
Bulk Metallic Glass
Production
Zr-based BMGs

Bulk metallic glasses (BMGs) are ideal candidates for airborne gravity gradiometer (AGG) flexures due to their unique mechanical properties. In this thesis, the role of processing variables in the production Zr-based BMGs by arc melting and suction casting was investigated and an electrochemical method for determining the degree of crystallization after electric discharge machining (EDM) was examined. Homogenization was most effectively obtained using multiple melting iterations and prolonged melting times. The difference between input and actual Zr concentration was found to be significant in arc melting and suction casting. Superior GFA was obtained using high purity argon purge gas and low purity Zr contrary to the consensus that GFA strictly increases with increasing raw material purities. The use of potentiostatic polarization in 1M NaNO3 for evaluating the degree of crystallization in Zr55Cu30Al10Ni5 samples after EDM may be feasible due to the dependence of passivation behaviour on the degree of crystallization.
R740S Mutation of Tcirg1 Mutation Affects Enamel Development in Osteopetrotic Mice
Keywords: Amelogenesis
Enamel
Osteopetrosis
Tcirg1
vacuolar ATPase

Abstract Osteopetrosis is characterized by sclerotic bone due to impaired osteoclasts. Many cases are associated with defects in the TCIRG1 gene encoding the a3 subunit of vacuolar-ATPase (V-ATPase). These patients have defects in bone, tooth eruption and enamel. To elucidate the role of V-ATPases in amelogenesis, we investigated the cellular distribution of a3, expression of enamel proteins, and quality of the enamel in a mouse with a mutation (R740S) in a3. In the homozygote (R740S/R740S), micro CT and SEM demonstrated a decrease in mineralization and thickness of the enamel. Using immunohistochemistry, the expression of the secretory stage protein, amelogenin remained in the R740S/R740S ameloblasts at day 9, concurrent with lower levels of the maturation stage proteins, amelotin and ODAM, suggesting a developmental delay. Low level expression of a3 was observed in the ameloblasts during the secretory stage. Our results suggest that a3-V-ATPases may play a role in amelogenesis, possibly by affecting protein secretion.
Investigating Simulated Driving Behaviour and Brain Activation in Mild Cognitive Impairment
Keywords: driving
fMRI
mild cognitive impairment
simulation

There are no guidelines or tools to help physicians assess the driving safety of patients with MCI. This study combined fMRI and driving simulation to compare the driving performance, and corresponding brain activation patterns, of patients with MCI and healthy controls. Patients with MCI committed significantly more driving errors compared to controls. Patients with amnestic multiple-domain MCI patients were at a greater risk of difficulty relative to those with amnestic single-domain MCI. Patients with MCI exhibited increased recruitment of frontal brain regions compared to controls, particularly during left turns with traffic. Patients with sd-MCI exhibited increased recruitment of frontal and medial regions across turning conditions, whereas patients with md-MCI exhibited decreased recruitment of frontal and medial regions. The results suggest that patients with MCI can demonstrate driving difficulties and deviations in brain activation compared to controls and that the areas and degree of difficulty vary across the subtypes of MCI.
Inhibition of Return: Underlying Mechanisms and Contributions of the Primary Motor Cortex (M1)
Keywords: Neuro-Motor

Inhibition of return (IOR) refers to the finding that response times (RTs) to targets are longer when targets are presented at a recently attended-to location relative to targets at new locations. The motor-based component of IOR was explored by investigating the contributions of M1 to IOR. Transcranial magnetic stimulation (TMS) was used to determine if the mechanisms associated with IOR are represented in M1. Participants completed a cue-target task with non-predictive exogenous cues. It was hypothesized that if the mechanisms underlying IOR are represented in M1, then the motor evoked potentials (MEPs) associated with the cued or uncued responses would mirror RTs. TMS of M1 altered RTs, however MEP data did not reveal an effect of cue location on M1 excitability. The data indicate a motor contribution to the IOR effect, but the question of where in the motor system the mechanisms associated with IOR is localized is unanswered.
Deconstructing Psychosis: Dismantling Oppression
Keywords: anti-oppression
indigenaity
psychosis
spirituality

Abstract This document deconstructs the term ‘psychosis’ through an exploration of the origins of this term, a personal narrative of this phenomenon, and the exploration of a multitude of perspectives from around the world, on experiences which fall into this category. Integrating the wisdom of five Indigenous and Alternative Health practitioners, and exploring several alternative mental health healing centre models, the limitations of the mainstream Western medical approach are presented .Also discussed, are the diversity and power of these alternatives and their possible combinations. This exploration is carried out using the Two-Eyed Seeing Framework, developed by Mi’kmaw Elders Albert and Murdena Marshall, of the Eskasoni First Nation in Cape Breton, Nova Scotia, which ensures readers appreciate each perspective on ‘psychosis’ in its own right, and invites readers to imagine and notice ways in which the healing perspectives presented, can be and are combined, in order to create new and important healing possibilities.
Human-robot Interactions for Single Robots and Multi-robot Teams
Keywords: Affect Recognition
Human-Robot Interaction
Multimodal Bi-directional Communication
Multi-Robot Team
Semi-Autonomous Controller
Urban Search and Rescue

For robots to successfully take part in bi-directional social interactions with people, they must be capable of recognizing and responding to human affect. Such robots would promote effective and engaging interactions with users. In this thesis, a multimodal bi-directional affect architecture is proposed that determines user affect using a unique combination of user body language and vocal intonation. In addition to one-on-one human-robot interactions, multi-robot teams can provide valuable assistance in Urban Search and Rescue (USAR) missions by exploring dangerous environments, while searching for victims. One of the main challenges an operator may face in controlling a multi-robot team is the simultaneous control of multiple robots while juggling between tasks and keeping situational awareness. This thesis also proposes a multi-robot collaboration architecture using a learning-based semi-autonomous controller that provides the ability to effectively allocate sub-tasks to robots to complete USAR missions.
Evaluating the Sociocultural Risks for Suicide Attempt in Schizophrenia
Keywords: Ethnicity
Genetics
Immigration
Psychiatry
Schizophrenia
Suicide

Sociocultural factors involved in immigration and ethnicity are believed to independently influence the risk for schizophrenia and suicidal behaviour. Schizophrenia patients are known to be at an increased risk for suicide. Though many risk factors have been identified, few have any significant clinical impact on predicting suicide. Whether immigration and ethnicity are potential risk factors for suicide attempt in schizophrenia has yet to be investigated. Schizophrenia patients with clear suicide attempt history, immigration history, self-reported ethnicity, and other sociocultural and clinical variables were recruited to test whether independently, or synthesized in a classification algorithm, these variables can accurately predict a history of suicide attempt. Both immigration and ethnicity had a non-significant association with suicide attempt. Inclusion of these predictor variables also did little to improve classification accuracy in our algorithms. Taken together, we found no evidence that these sociocultural factors have a significant influence on the risk for suicide attempt in schizophrenia.
Patterned Linear Systems and Control
Keywords: Control Theory
Group Theory
Linear Systems
Pattern
Symmetry
Systems

A method to characterize the symmetries inherent within physical systems via automorphism groups has already been established. In this thesis, we elaborate on this method and define a special reduced form to which the system matrices of a linear system can be decomposed based on these inherent patterns. We employ this decomposition and the resulting block diagonal form to adapt basic control theory concepts such as controllability and stabilizability to a pattern-preserving framework. We give a pole placement algorithm that synthesizes a feedback matrix that is constrained by the patterns of the system. Moreover, we apply our patterned framework to traditional control problems such as stabilization by measurement feedback and output stabilization, and give pattern-preserving feedback synthesis procedures for these problems. Finally, we provide a set of computational tools that can be used to nd the aforementioned decomposition and generate pattern-preserving feedbacks for a given patterned system.
Impact of Irradiance Change on MPPT and Flicker Phenomenon of Solar-PV Units
Keywords: Flicker
IEC Flickermeter
Irradiance
MPPT
Solar-PV

This thesis investigates the effect the solar-PV array's response to a rapid change in irradiance has on the individual solar-PV unit and electric power distribution system to which it is connected. The study system is a weak, radial distribution system with 30% solar-PV penetration levels. Specifically, 3 solar PV units, each 1.5 MW capacity, are distributed downstream in the feeder. First, at the individual, solar PV unit level, an augmented incremental conductance (IC) method for maximum power point tracking (MPPT) is proposed to improve DC power control performance in response to change in irradiance, i.e., cloud movement. The augmented MPPT algorithm shows up to 2.49 % energy harvest improvement when compared to the classical IC method. Second, at the system level, the impact of rapid changes in irradiance on voltage flicker is evaluated. It is shown that flicker levels are kept well below acceptable levels (the highest Pst observed is 0.21 pu) for citable weather patterns.
Activation of a Medullary Respiratory Motor Circuit by Remote Control
Keywords: Apnea
Chemogenetics
DREADD
Hypoglossal
Obstructive
Sleep

Obstructive sleep apnea (OSA) can be triggered by reduced tongue muscle tone during sleep. The hypoglossal motor nucleus (HMN) is the source of motor output to the tongue, and is a logical pharmacological target for treatment. Targets in this region exist; drugs able to specifically modulate them do not. To test the feasibility of this approach, we modelled a drug-receptor interaction at the HMN by selectively activating engineered receptors inserted into the HMN. Receptor activation by a systemically administered drug increased tongue muscle activity during sleep. Importantly, tongue muscle activity was increased during both rapid eye movement (REM) and non-REM sleep to near-waking levels. The results of this thesis show that selective activation of a pharmacological target locally expressed at the HMN results in sustained tongue muscle activity throughout sleep. This establishes proof-of-principle for modulating a restricted target at the HMN as a viable strategy for pharmacologically treating OSA.
Multi-agent Learning in Coverage Control Games
Keywords: Control
Game Theory
Machine Learning
Multi-agent
Robotics

Multi-agent systems have found a variety of industrial applications from economics to robotics. With the increasing complexity of multi-agent systems, multi-agent control has become a challenging problem in many areas. While studying multi-agent systems is not identical to studying game theory, there is no doubt that game theory can be a key tool to manage such complex systems. Game theoretic multi-agent learning is one of relatively new solutions to the complex problem of multi-agent control. In such learning scheme, each agent eventually discovers a solution on his own. The main focus of this thesis is on enhancement of multi-agent learning in game theory and its application in multi-robot control. Each algorithm proposed in this thesis, relaxes and imposes different assumptions to fit a class of multi-robot learning problems. Numerical experiments are also conducted to verify each algorithm's robustness and performance.
Delayed Expression of Plasticity in Neuronal Excitability Induced by Co-activation of NMDAR and mGluR at a Developing Central Synapse
Keywords: development
excitability
neurotransmission

The development of effective neurotransmission in central synapses requires intricate regulation of synaptic receptors and active intrinsic membrane properties. Previous studies have shown that patterned activity can concurrently activate NMDARs and mGluRs and increase the fidelity of neurotransmission at high rates by translational and post-translational modifications of glutamate receptors. It is however unknown whether or how activity drives the development and maturation in the intrinsic excitability of central neurons. Using the developing calyx of Held-MNTB synapse as a model, we examined this issue by using NMDA and DHPG to selectively co-activate postsynaptic NMDARs and Group I metabotropic glutamate receptors (mGluRs) of postsynaptic neurons in acute slices from the auditory brainstem of prehearing mice. We found that co-activation of NMDAR and mGluRs induced a delayed expression of plasticity in the action potential waveform and a multiplicative output modulation of the I/O relationship in response to injected current steps. We performed whole-cell voltage-clamp recordings to determine potential mechanisms underlying observed changes in AP waveform. The average density, kinetics and the ratio of maximal spike-generating (INa/IK) currents of isolated sodium and potassium currents were comparable in naive compared to treated cells. A systematic exploration of conductance based models showed that multiple combinations of modifications to conductance densities could underlie the observed plasticity. These results suggest that selective co-activation of NMDAR and mGluR can regulate multiple intrinsic membrane properties to play a role in shaping action potential waveform and the ability to spike at high-frequencies.
Characterization of Mammalian ER Quality Control Systems in the Context of Select Human Pathologies
Keywords: Endoplasmic reticulum
ERAD
FKBP10
Prion protein
Protein folding
Quality control

Quality control (QC) systems in the endoplasmic reticulum (ER) are established by intricate networks of molecular chaperones and foldases, and sophisticated degradative processes such as the ER-associated degradation (ERAD) pathway that promote the proper folding of translocated nascent chains and clearance of misfolded proteins, respectively. This thesis demonstrates my efforts to expand upon the current understanding of ERQC mechanisms, first by identifying novel components of the mammalian ERAD pathway. From a genome-wide shRNA screen conducted in the context of a viral immunoevasion-based ERAD model system, several potential candidates were selected, validated, and identified as promising targets for future investigation. Secondly, the ER-resident FKBP-type peptidyl prolyl isomerase, FKBP10, was verified as a regulator of cellular prion protein (PrPC) biogenesis, and newly identified as a potential therapeutic target against prion diseases as its depletion resulted in PrPC attenuation â an effective method of impeding disease progression - via proteasomal and lysosomal degradation pathways.
Mechanisms of Neurogenesis Mediated Forgetting
Keywords: Dentate gyrus
Forgetting
Hippocampus

Memories allow experiences to have some permanence in our minds. Increasing adult neurogenesis in the dentate gyrus of the hippocampus has been shown to reduce this permanency, leading to forgetting. The hippocampus encodes memories through the activation of a selection of neurons and successful memory retrieval is believed to involve reactivation of these neurons. Although successful memory retrieval has been linked to reactivation, we investigate whether decreased reactivation is the mechanism that underlies forgetting. This is achieved by permanently tagging neurons activated during the acquisition of a contextual fear conditioning task and analyzing dentate gyrus neuronal reactivation levels of forgotten memories after 28 days of exercise-induced neurogenesis. The data shows less reactivation in animals that demonstrated neurogenesis-induced forgetting, and a positive correlation between retrieval success and reactivation levels. These results indicate that neurogenesis-mediated forgetting can be explained at the cellular level as a reduction of complete reactivation of encoding neurons.
Socioeconomic Discrepancies in Children’s Accessibility to Health Promoting Resources: An Activity Space Analysis
Keywords: Accessibility
Activity space
Children
Food environment
Mobility
Physical activity

Approximately one third of Canada’s youth are overweight or obese. Children living in low socioeconomic status (SES) households are at greater risk of this condition. Little research examines how mobility and time shape accessibility to food environments and physical activity (PA) facilities, two likely determinants of health expected to vary by SES. Using data from Project BEAT, a study investigating the built environment and Toronto schoolchildren’s active travel, this thesis examines how SES shapes children’s accessibility to food establishments and PA facilities. The activity space construct is used in order to incorporate mobility and time into measures of accessibility. Results indicate that higher SES is associated with greater accessibility and access to PA facilities and lower accessibility to fast food establishments. Furthermore, accessibility to PA facilities and retail food establishments varies over the week. This thesis contributes a more comprehensive understanding of how mobility, time, and SES shape children’s health.