VictorJuiz/thesis huggingface dataset:
The Role of AMP-activated Protein Kinase in Alleviating Insulin Resistance in Hypothalamic Neurons

Insulin signaling in the brain is vital to maintain whole-body glucose and energy homeostasis. AMP-activated protein kinase (AMPK) is a key enzyme that acts as a regulator of energy homeostasis within insulin sensitive tissues. To investigate the role of AMPK on insulin resistance within the hypothalamus, the rHypoE-19 and mHypoA-NPY/GFP hypothalamic cell lines were used. Both of these cell lines express the insulin receptor and accompanying downstream molecules involved in normal insulin signaling. To induce cellular insulin resistance, the neuronal cell lines were exposed to chronic insulin for sustained periods. It was found that pre-treatment with the AMPK activator, AICAR, had an effect on insulin action and was able to slightly improve the state of chronic insulin-induced resistance within both cell lines. Therefore, these studies provide a clearer understanding of the potential role of the AMPK pathway in improving the state of cellular insulin resistance within the hypothalamus.

Keywords: Energy Homeostasis
Hypothalamus
Insulin Resistance
Obesity
Type 2 Diabetes
Advisor: Wojtowicz, Martin
Application of Imputation Methods in the Analysis of Freight Trip Generation in the Greater Toronto and Hamilton Area

Missing data is a common issue in empirical research, especially in complex surveys involving a large number of respondents. In 2012-13, a shipper-based, establishment survey was conducted of 1006 small and medium-sized firms and twelve large firms in the Greater Toronto and Hamilton Area; however, there exist complete records for only about 11 percent of the firms. In this study, several single and multiple imputation techniques were evaluated to determine the best method to impute this dataset. Once the entire dataset was imputed, freight trip generation models were developed using the imputed datasets and compared to models developed based on the complete data. The research concluded that imputation is useful when developing models as it allows for the usage of the full dataset, resulting in parameter estimates of greater power. It also allows for greater flexibility in modelling, as richer models with more explanatory variables can be considered.

Keywords: freight trip generation
imputation
missing data
Advisor: Roorda, J. Matthew
Controlling Biomass Ash Alkalinity for Land Application

Burning biomass wastes generates large quantities of ash products which contain plant nutrients, such as Ca, Mg, K, and P. These nutrients could be returned for reforestation. However, the ash high alkalinity presents some challenges in terms of direct land application. The high alkalinity affects the leachability of various ash components and adversely affects ground vegetation. In this thesis, it will be shown that CO2 can effectively decrease ash alkalinity at room temperature. From the study, it was found that the rate carbonation depends heavily on the moisture content of the ash and the CO2 partial pressure. From a practical point of view, a combined process of ash pelletization and carbonation was tested to have some potential for industrial application. It was found that the time required for carbonation equals the time it takes for the wetted pellet, regardless of the size, to dry at 15 vol% of CO2.

Keywords: Ash alkalinity
Carbonation
Advisor: Kirk, W Donald
Guided Wave Inspection of Supported Pipe Locations Using Electromagnetic Acoustic Transducers

The goal of the work in this thesis is to develop a rapid and reliable NDT system to detect hidden corrosion at pipe-support interfaces using Electromagnetic Acoustic Transducers (EMATs). Since there are often many support interfaces over a piping run, information is needed on the support interface conditions to optimize subsequent detailed inspections.In this work it is important to be able to isolate the effects produced from the support interface and the incident guided wave. To do this an optimum EMAT operating point is first selected, then the support interfaces and wall loss type defects are independently analyzed through experimentally validated finite element models. It is found that operating the SH1 plate wave mode near the `knee' of its dispersion curve gives a high sensitivity to wall loss type defects while experiencing a minimal effect from the support contact region.

Keywords: corrosion defect
EMAT
Guided Wave
Non-destructive testing
Pipe Support
Shear Horizontal
Advisor: Snclair, Anthony
Implementation and Application of a Method for Measuring Traction Forces to Characterize Deficient CNP Signaling in Mouse Fibroblasts

Adherent cells respond to changes in their microenvironment by generating internal forces that are transferred to the substrate to which they are attached. Manipulation of cellular signaling pathways also influences the response to these changes and can direct cells to pathological outcomes. C-type natriuretic peptide (CNP), through the NPR-B receptor, has been shown to protect quiescent fibroblasts in heart valves from differentiating into myofibroblasts that contribute to development of calcific aortic valve disease (CAVD). Here, I implemented and validated a method for quantifying cellular traction forces

Keywords: Aortic Valve Disease
C-type Natriuretic Peptide
Mechanobiology
Myofibroblasts
Traction Force Microscopy
Advisor: Simmons, A Craig
Surface Texture Consistency in Object and Background Perception

Seminal work on global processing has suggested that the precedence of global image features is an inherent property of visual perception. Consequently, interference from global percepts may influence the perception of local elements. Investigations of scene processing have been consistent with this suggestion, demonstrating that the parahippocampal place area (PPA) represents scenes by processing global spatial properties. Recent investigations have further revealed that PPA is sensitive to processing non-spatial visual cues (such as surface texture) in both object and scene perception. In the present study, we investigated potential global interference effects in object-scene perception when attending to spatial and non-spatial visual features in both simple figure-ground representations and more complex real-world scenes. Results revealed that non-spatial surface properties such as texture can form a contextual link between the processing of object and background information in scene perception, and this interactive processing proceeds from the global to local scale of attention.

Keywords: context
form
global image feature
Scene and object perception
texture
Advisor: Cant, S Jonathan
Local and Global Structural Architecture Supports Functional Organization in the Aging Brain

Neuroscience research suggests that local and global functional interactions throughout the human brain are modulated by the underlying anatomical architecture. Age-related changes of anatomical tracts suggest a potential for concomitant changes in structure-function coupling. We compared functional connectivity inferred from spontaneous BOLD fMRI with structural connectivity inferred from DTI in a sample of 47 adults ranging from 18 to 82 years of age. We noted that the strength of structural and functional connectivity decreased in most regions as subjects aged. Local regionwise structure-function correspondence varied across the age spectrum. We also found that the structural architecture upholds the functional modular organization at a global level, such that regions are more densely connected within their functionally defined module, and that this varies with age. Tracts from structural hubs may actually strengthen within functional modules with age, such that the structural core increasingly supports functional organization throughout the aging process.

Keywords: aging
function
neuroimaging
structure
Advisor: McIntosh, Randall
Characterization of the Role of Ubiquitin Protein Ligase E3 Component N-recognin 4 (UBR4) in the Murine Circadian Clock

Ubiquitination is an important post-translational modification in the molecular clock that regulates degradation of clock proteins through ubiquitin ligases. However, no ubiquitin ligase has been implicated in the photic entrainment pathways in mammals thus far. In this thesis, I characterized the physiological and molecular phenotype of a new ubiquitin ligase named UBR4 in the murine circadian clock. UBR4 is expressed throughout the suprachiasmatic nucleus in a time-of-day-dependent fashion and is light-inducible in the early subjective night. Homozygous ubr4 knockout are embryonic lethal, therefore heterozygous ubr4 mice (ubr4+/-) were used to study its physiological role in the circadian clock. I found that mice with reduced expression of UBR4 show differential phenotype in circadian paradigms that involve chronic light disturbances. Furthermore, preliminary data suggest that casein kinase 2 beta subunit is a potential substrate of UBR4, affecting molecular clock component PER in vivo and in vitro.

Advisor: Cheng, Hai-Ying Mary
Development of an Ambulatory Wearable Sensor System for Behavioural Neurocardiac Training

In this project, an ambulatory wearable sensor system was developed to deliver Behavioural Neurocardiac Training (BNT) with heart rate variability biofeedback for blood pressure and stress management in home settings. The system consists of a wearable ECG sensor and a smartphone application. The sensor was designed as a patient-friendly modular patch to be worn on the user's chest using standard electrodes. It wirelessly streams ECG in real-time using Bluetooth Low Energy. The smartphone application guides users through the BNT exercises using structured, audio-guided lessons that train a paced breathing technique using real-time biofeedback and stress recovery exercises. The feasibility of this system was evaluated in a pilot study with six participants. The overall response to the system was positive, and user satisfaction was high. It is expected that this system may offer a complementary approach to blood pressure and stress management at home, and reduce current accessibility barriers.

Keywords: biofeedback
mobile health
wearable sensor system
Advisor: Cafazzo, Joseph
Exploring Mechanisms Underlying Retinitis Pigmentosa by Using Temperature Sensitive Alleles in Yeast

Retinitis pigmentosa (RP) is characterized by progressive degeneration of the photoreceptors and visual field defects. No drug treatment has yet been found for this disease. Mutations in more than 60 genes are known to cause RP. One group of genes that was found to be mutated in retinitis pigmentosa is encoding pre-mRNA processing proteins; hPrp3, hPrp6, hPrp8, hPrp31, and hBrr2 that are homologous between human and Saccharomyces cerevisiae. In the project described here, I introduced the RP-related mutations into their yeast homologs and tested for temperature sensitivity. Two out of thirteen tried mutations resulted in a temperature sensitive phenotype. Using both available ts strains and ts strains containing RP point mutations, extragenic suppressors were isolated. Whole genome sequencing was used to identify the suppressor genes. As chemical perturbations may mimic genetic perturbations, these suppressor genes can potentially lead us to new alternative drug targets for this genetic disease.

Keywords: Genetic suppression
Retinitis Pigmentosa
Spliceosome
Temperature sensitive alleles
Advisor: Boone, Charles
Comparing the Effects of Self- and Instructor-Regulated Learning on Skill Acquisition, Retention and Trainees' Learning Approches

During instructor-regulated learning (IRL), trainees must reconcile the instructor's teaching approaches with their own learning approaches. Conversely, trainees engaged in self-regulated learning (SRL) may benefit from developing individualized learning approaches. We compared the effects of SRL to IRL on cardiac auscultation skill acquisition and retention, and on trainees' transfer of learning approaches to another session. After randomization (SRL or one-on-one IRL groups), novice medical students (n=32) practiced diagnosing simulated murmurs and then completed a post-test. Two-weeks later, participants completed a retention test, practiced diagnosing new simulated murmurs, and completed another post-test. There were no between-group differences on any performance-based assessment. Most IRL participants did not use the learning approach in session two that instructors taught them in session one. Interview data suggest the instructor's presence had both positive and negative impacts on learning. The findings highlight factors that prevent IRL training from having the benefits supervisors expect from their teaching.

Keywords: Cardiac
Education
Instructor
Self-regulation
Advisor: Moulton, Carol-anne
Measuring Attentional Bias Among Abstinent Smokers with a Manual Aiming Task

Attentional bias (AB) is exhibited by substance users for addiction-related stimuli, influencing consumption, craving, and relapse. Due to limitations of AB measurements, this study developed and evaluated a novel method using manual aiming (MA). Participants completed modified visual dot-probe tasks while monitoring their eyes and limb movements. Reaction time (RT), movement time (MT), and limb trajectory (LT) were measured and compared between non-smokers (n=15) and abstaining smokers (n=13) and within smokers. Using 3 (probe) x 2 (accompanying image) x 2 (group) ANCOVAs, controlling for age, there were no significant differences for RT or LT. Trends for group and condition differences in MT were found although in the opposite direction. As expected, cravings negatively correlated with the time elapsed to complete MA. There was some tentative evidence to suggest that AB may have properties that can be examined by MT. Replication is needed with a larger sample and more dependent smokers.

Keywords: attentional bias
manual aiming
smoking
Advisor: Faulkner, Guy
Geographic Effects on Vehicle Reliability: Developing Proportional Hazards Models for a Deployable Military Vehicle

Unlike many industries that have their equipment in one location with consistent usage patterns, armies move their vehicles between different geographic locations with varying environmental, and usage conditions. This creates interesting conditions for study, as those geographic changes can be studied to detect their effect on system reliability.Unfortunately, this is not being fully exploited, due in part to the poor capture and storage of information, a problem faced by many operators of maintenance databases.This thesis develops a method to characterize failure data contained in a maintenance database using a standardized naming system, and applies a proportional hazards model for each geographic location using covariates to represent the conditions. In addition to understanding how a system has performed, the proportional hazards model will allow geographic location factors to be used in predicting system reliability and spares parts requirements in a new location.

Keywords: Armoured Vehicles
Military
Preventive Maintenance
Proportional Hazards Model
Reliability
Spare Parts
Advisor: Jardine, KS Andrew
Light Management across the Nano and Macro Lengthscales to Enhance Photovoltaic Device Performance

Colloidal quantum dot photovoltaics (CQDPV) have the potential to be a low cost and renewable source of electricity, with state-of-the-art CQDPV certified at a power conversion efficiency of 8.5%. What prevents further breakthroughs in performance is the limitation placed by the electron diffusion length of CQD materials. The compromise between two interrelated drivers of solar cell performance - the ability to extract charge carriers versus the amount of photons being absorbed - needs to be solved. There are solutions available on both the macro and the nanoscales, through careful design of the device architecture and substrates. Herein, we utilized a structured plasmonic electrode for the nanoscale case and a folded-light-path architecture for the macroscopic case to improve light absorption. Through these techniques, we observe 20% improvement in short-circuit current, leading to a 10% enhancement in power conversion efficiency. In addition, the operational mechanisms and design constraints for integrating these techniques are discussed.

Keywords: Colloidal quantum dots
Folded light path
Photovoltaics
Plasmonics
Advisor: Sargent, H Ted
Biomechanics of Acute Total Hip Arthroplasty after Acetabular Fracture: Plate vs Cable Fixation

The incidence of complex acetabular fractures is increasing worldwide, especially in the elderly. Fixation methods currently used surgically have no biomechanical justification. Therefore, this study compared the standard plate versus three cable techniques for anterior column plus posterior hemitransverse acetabular fractures in synthetic hemipelves. Phase I employed FEA validated by non-destructive mechanical testing. Phase II entailed destructive comparison of the superior cabling method from Phase I versus the standard plating procedure. Phase I identified the Mouhsine cable method as providing the best mechanical stability (i.e. based on lowest peak bone stress) among the cable techniques. Phase II demonstrated the Plate group's superiority over the Mouhsine group for 2 outcomes (i.e. stiffness and failure force at clinical failure), its inferiority for 2 outcomes (i.e. failure displacement and gapping for posterior markers at mechanical failure), and statistical equivalence for the remaining outcomes. This investigation has implications for surgical repair of this injury.

Keywords: Acetabulum
Arthroplasty
Biomechanics
Cable
Fixation
Hip
Advisor: Schemitsch, H Emil
Guidance of Selective Attention by Conceptually- generated Working Memory Templates

We tested whether colour concepts associated with words held in verbal working memory (WM) could guide selective attention. Participants held one or three words in WM while performing a visual search during the delay period. Critically, the word(s) were semantically associated with a colour concept (e.g., lipstick, tomato), which matched the colour (e.g., red) of either a target or a distractor in the search array. In Experiment 1, search times were faster when the colour concept matched a target and slower when the colour concept matched a distractor. In Experiment 2, we eliminated the effect by extending the delay between WM encoding and search, suggesting that the effect is transient. Finally, we found that modulation of search times by verbal WM correlated with visual WM capacity (k). Overall, our results show that amodal conceptual knowledge can activate a perceptual attentional template, which enhances processing of subsequent sensory input.

Keywords: Biased Competition
Short-term Memory
Visual Attention
Visual Search
Visual Working Memory
Working Memory
Advisor: Ferber, Susanne
Hand Position Affects Perceptual Grouping

Over the past decade evidence has accumulated showing that performance of attention, perception, and memory related tasks are influenced by placing the observer's hands near the stimuli. Two theories have been proposed to account for these effects. The attentional account holds performance is altered due to changed attentional prioritization of hands-proximal space, while the differential pathways hypothesis holds processing of stimuli near the hands is dominated by the magnocellular visual pathway resulting in the variety of documented effects. Here we test whether perceptual grouping processes are inhibited in hand-proximal space. Consistent with previous work on object-based attention, we find a benefit for the visual object in the hands-distal, but not the hands-proximal, condition suggesting perceptual grouping is impaired near the hands. This change in perceptual grouping processes cannot be explained solely by an attentional account of visual processing changes near the hands.

Keywords: near-hand vision
object perception
perception and action
perceptual grouping
Advisor: Pratt, Jay
Chiral Diamine-based Reduction and Oxidation Catalysts

Asymmetric catalysis remains one of the most significant ways for introducing chirality into prochiral molecules. There is much interest in elucidating mechanistic details and optimizing conditions for preexisting systems. Using a combination of experimental and computational methods, we separately explored two reactions: asymmetric transfer hydrogenation and alkene epoxidation. For the diamine-based hydrogenation catalyst, a series of diphenylethylenediamine derivatives were synthesized and used to test the electronic effect of diamine ligands on the rate of hydrogenation. Contrary to previous findings, we report virtually no difference in catalytic activity between the various ligands. Computational analysis consolidates our results. For the manganese-salen catalyzed epoxidation, we present an original mechanism to explain the observed stereoselectivity. Instead of the traditional "side-on approach", we propose that epoxidation proceeds through a planar transition state with sp2 hybridized manganese-oxo oxygen. This model correctly predicts the sense and degree of stereoselectivity for a number of catalyst and substrate systems.

Keywords: diamine
epoxidation
hpen
hydrogenation
salen
stereoselectivity
Advisor: Chin, Jik
Evaluation of Low-cost MEMS Accelerometers and Investigation of Inertial Algorithms for Dead Reckoning in Railway Environment

Low-cost micro-electro-mechanical systems (MEMS) accelerometers are gaining momentum in the defence, aerospace, transportation, and automotive industries. While highcost accelerometers are being used on subway trains for their signalling systems, this work investigates the possibility of replacing them with low-cost MEMS devices. To achieve this goal, a 3D printer was modied for use as a three-dimensional motion platform and sensors were tested based on various characteristics. In addition, the sensors were tested on subway trains. The results show that the Kionix KXRB5 accelerometer performs the best, even out-performing the high-end sensor tested. Finally, inertial algorithms were developed that were able to estimate displacements to below 5% error on the evaluation platform and subway line. Although realtime displacement estimations were not accurate due to unstable bias due to tilting, these inertial algorithms use only the accelerometer sensor and can update displacements at points of zero velocity.

Keywords: accelerometer
localisation
MEMS
navigation
robotics
sensors
Advisor: Johns, A David
Glucocorticoid-Induced Osteoporosis Management Among Seniors

Background: Chronic oral glucocorticoid (GC) therapy is the leading cause of secondary osteoporosis, resulting in rapid bone loss and increased fracture risk. Objective: To examine trends in GC-induced osteoporosis management, by sex and over time. Methods: Using Ontario healthcare utilization data, we determined the proportion of chronic oral GC users (age 66+) who received a bone mineral density test and/or osteoporosis treatment within 6 months of starting chronic GC therapy. Results: We identified 72,099 male and 95,975 female patients on chronic GC therapy between 1996 and 2012. Overall, 15% of men and 36% of women on chronic oral GC therapy received osteoporosis management. However, among patients without prior osteoporosis management, only 12% of men and 23% of women received osteoporosis management within 6 months. Conclusion: GC-induced osteoporosis management improved significantly over time in both sexes yet remains low, particularly among men. This represents a missed opportunity for fracture prevention among patients requiring prolonged GC therapy.

Keywords: Glucocorticoids
Health Services Research
Osteoporosis
Practice Patterns
Advisor: Cadarette, M Suzanne