VictorJuiz/thesis huggingface dataset:
Recurrence of Inguinal Hernia in General and Hernia Specialty Hospitals in Ontario, Canada

BACKGROUND: We compared hernia recurrence rates in patients undergoing primary elective inguinal hernia repair at general hospitals with the Shouldice Hospital in Ontario, Canada. METHODS: We conducted an administrative data analysis of persons who underwent inguinal hernia repair in Ontario, Canada from 1993-2007. Risk of recurrent hernia repair was estimated according to hospital type and volume, using Cox proportional-hazards regression models. RESULTS: Recurrence risk in the lowest volume quartile was 5.7%, compared to 3.9% at high volume general hospitals and 1.1% at the Shouldice hospital. Compared to persons who had surgery at the lowest volume hospitals, hernia recurrence among Shouldice Hospital patients was substantially lower after adjustment for confounding variables (hazard ratio 0.18, CI (0.16 to 0.19), P <0.001). CONCLUSIONS: Persons who had elective primary inguinal hernia repair at the Shouldice Hospital had a substantially lower risk of recurrence than those treated at general hospitals, including high volume general hospitals.

Keywords: Surgery
Inguinal Hernia
Shouldice
Recurrence
Advisor: Urbach, David Robert
A Thermodynamic Investigation of the PVT, Solubility and Surface Tension of Polylactic Acid (PLA)/CO2 Mixtures

This thesis illustrates a comprehensive study on the PVT, solubility and surface tension properties of polylactic acid (PLA) with dissolved CO2 based on thermodynamic models. The solubility of CO2 in PLA melt was calculated by means of a gravimetric method, using a Magnetic Suspension Balance (MSB). The swelling volume of the polymer/gas mixture due to dissolution of gas was compensated for by direct measurement through a view cell or by theoretical models such as Simha Somcynsky (SS) - Equation of State (EOS) and Sanchez Lacombe (SL) - Equation of State (EOS). Three grades of PLA (i.e., PLA3001D, PLA8051D, and PLA4060D) were chosen. It was observed that the pressure, temperature, D-content and Molecular weight variance had an effect on the swelling and solubility. The surface Tension of PLA/CO₂ mixture was also calculated from the captured image using the Axsymmetric Drop Shape Analysis (ADSA). The effects of varying the pressure, temperature, and molecular weight on surface tension were investigated.

Keywords: PLA
Solubility
D-content
Advisor: Park, Chul B.
Neuromuscular Control of Aerodynamic Power Output via Changes in Wingbeat Kinematics in the Flight Muscles of Ruby-throated Hummingbirds (Archilochus colubris)

While producing the highest power output of any vertebrate, hovering hummingbirds must also precisely modulate the activity of their primary flight muscles to vary wingbeat kinematics and modulate lift production. By examining how electromyograms (EMGs) and wingbeat kinematics of hummingbirds change in response to varying aerodynamic power requirements during load lifting trials and air density reduction trials, we can better understand how aerodynamic power output is modulated via neuromuscular control. During both treatments increased lift was achieved through increased stroke amplitude, but wingbeat frequency only increased during air density reduction trials. These changes in wingbeat kinematics were matched by increased EMG intensities as aerodynamic power output requirements increased. Despite the relative symmetry of the hovering downstroke and upstroke, the timing of activation and number of spikes per EMG burst were consistently different in the supracoracoideus compared to the pectoralis, likely reflecting differences in muscle morphology.

Keywords: ruby-throated hummingbird
Archilochus colubris
electromyography
flight
heliox
load lifting
stroke amplitude
wingbeat frequency
Advisor: Welch, Kenneth
The Transfer of Ethyl Glucuronide in the Dually Perfused Ex Vivo Placental Perfusion Model: Implications for Alcohol Screening during Pregnancy

Alcohol consumption during pregnancy can lead to Fetal Alcohol Spectrum Disorder, and because maternal self-reports are often unreliable, a biomarker of alcohol use during pregnancy is needed to accurately determine fetal exposure. Ethyl glucuronide (EtG) is a direct metabolite of ethanol that has been detected in the meconium of infants born to mothers who consumed alcohol during pregnancy. In the current study, a method was developed and validated for EtG detection in placental perfusate and tissue using gas chromatography-mass spectrometry. Subsequently, the ex vivo human placental perfusion model was used to investigate whether EtG crosses the human placenta. The validated GC-MS method showed sufficient sensitivity in detecting EtG in placental perfusate and tissue. EtG crossed the placenta slowly and transfer was incomplete after 3 hours of perfusion. EtG appears to cross the human placenta and, hence, to represent both maternal and fetal exposure to alcohol.

Keywords: ethyl glucuronide
placenta
Advisor: Koren, Gideon
An Integrated Modelling Approach to Estimate Urban Traffic Emissions

Vehicular emissions contribute significantly to poor air quality in urban areas. An integrated modelling approach is adopted to estimate microscale urban traffic emissions. The modelling framework consists of a traffic microsimulation model, a microscopic emissions model, and two dispersion models. This framework is applied to a traffic network in downtown Toronto to evaluate summer time morning peak traffic emissions during weekdays for carbon monoxide and nitrogen oxide. The model predicted results are validated against sensor observations with a reasonably good fit. Availability of local estimates of ambient concentration is useful for accurate comparisons of total predicted concentrations with observed concentrations. Both predicted and observed concentrations are significantly smaller than the National Ambient Air Quality Objectives established by Environment Canada. Sensitivity analysis is performed on a set of input parameters and horizontal wind speed is found to be the most influential factor in pollutant dispersion.

Keywords: traffic microsimulation
emission
dispersion modelling
Advisor: Roorda, Matthew J.
MacLean, Heather L.
The UN 1267 Sanctions Regime: Due Process and Intelligence Evidence

This article examines the UN Security Council’s 1267 sanctions regime. Initially adopted in 1999, the sanctions regime has undergone various reforms in response to criticisms from various channels, including domestic and regional courts. Despite the reforms, the 1267 regime continues to fall short of the standards required to ensure a fair and public hearing by a competent, independent and impartial tribunal established by law. Reviewing recent developments, the article addresses the need for additional safeguards and possible reform options. In particular, the paper explores international standards for reviewing secret intelligence evidence based on the jurisprudence of international criminal tribunals and argues that such evidentiary procedures have the potential to be used as a guide for reviewing 1267 listing.

Advisor: Roach, Kent
Ovarian Toxicity in Breast Cancer Survivors

The long-term natural history of ovarian reserve after adjuvant chemotherapy for breast cancer has been poorly described. We recruited 52 breast cancer survivors treated with adjuvant chemotherapy before 40 years of age who remained premenopausal after chemotherapy treatment. Twenty (38.5%) were more than five years out from treatment. Ovarian reserve estimates were compared with a control group. Anti-Müllerian hormone (AMH), follicle stimulating hormone and luteinizing hormone demonstrated significant differences consistent with reduced ovarian reserve in breast cancer survivors. Mean AMH was 6.65 pmol/l in survivors compared to 17.43 in controls (p < 0.001). Attained age and age at the time of treatment were correlated with AMH levels in breast cancer survivors. Conclusion: Ovarian reserve is significantly reduced in young breast cancer survivors. Age is the major predictor of AMH level in survivors. A 35 year old breast cancer survivor has an AMH level similar to a 45 year old control.

Keywords: Breast cancer survivors
Ovarian toxicity
Antimullerian hormone
Advisor: Hodgson, David
The Role of Genetic Variants Regulating the Oxytocin-­Vasopressin System in Childhood-­onset Aggression

Background: Antisocial behaviours in adolescents are costly in social and financial terms. These behaviours are heritable and genetic variants may be contributing factors. The purpose of this study was to determine whether genetic variants regulating the oxytocin-vasopressin (OXT-AVP) system were associated with aggressive behaviours. Methods: A sample of children displaying extreme, persistent and pervasive aggressive behaviours was first compared to adult controls (160 cases-160 controls) and then to child controls (182 cases-182 controls). We also tested for interactions between oxytocin receptor (OXTR) single nucleotide polymorphisms (SNPs) and serotoninergic polymorphism, 5-HTTLPR. Results: Using adult controls, OXTR SNPs rs6770632 and rs1042778 were associated with aggressive behaviours in females and males, respectively. However, using child controls revealed significant effects of AVPR1A rs11174811 in females; OXTR rs237898, rs237902 and AVP rs3761249 in males. There were no significant interactions between 5-HTTLPR and OXTR SNPs to predict aggression. Conclusion: OXT-AVP SNPs may be associated with aggressive behaviours.

Keywords: genetics of aggression
children
Advisor: Beitchman, Joseph
Contaminants in Lake Erie Fish Communities: A Bayesian Evaluation

Increasing awareness about the presence and ecological ramifications of toxic, persistent and bioaccumulative contaminants within the Great Lakes system spurred the implementation of numerous bans and emissions restrictions over the past few decades. Due to their high trophic status in food webs and the critical link they serve with human consumers, fish species have historically been monitored to assess the relative success of such remedial efforts within the region and to simultaneously ascertain the current risks posed to local humans. Using Bayesian dynamic linear modelling, this project first aimed to evaluate temporal trends of various organochlorine contaminants within Lake Erie fish communities, the results of which generally indicated decreasing trends through time. The second half of this study used a similar Bayesian approach to propose a framework for updating fish consumption advisories, with specific attention paid to the acknowledgment of uncertainty and natural variability when producing such consumption guidelines.

Keywords: Fish contamination
Organochlorines
Fish consumption advisories
Bayesian inference
Dynamic linear modelling
Bioaccumulation
Lake Erie
DDT
Pesticides
Advisor: Arhonditsis, George
Characterizing the Expression and Function of FLRT2 in the ATDC5 Chondroprogenitor Cell Line

Expression studies have implicated Fibronectin Leucine Rich Transmembrane protein 2 (FLRT2) in cranial neural crest cell migration and pre-chondrogenic cell condensation during craniofacial skeletogenesis. This aim of this study was to characterize the expression of FLRT2 and its relationship to the extracellular matrix (ECM) in ATDC5 chondroprogenitor cells. Immunofluorescence studies localized FLRT2 to the cell membrane as well as exracellularly, where it colocalized with fibronectin. FLRT2 was identified in the ATDC5-derived ECM after cell extraction. Further to its colocalization with fibronectin, FLRT2 associated with fibronectin-coated beads in cell cultures. Co-immunoprecipitation confirmed that FLRT2 and fibronectin interact, either directly or indirectly. Blocking fibronectin fibril formation in ATDC5 cell cultures demonstrated a concomitant decrease in extracellular FLRT2 accumulation. It appears that FLRT2 may exist in both a membrane-bound and a shed form. Either or both of these forms may participate in cell-ECM interactions in cooperation with fibronectin or other ECM proteins.

Keywords: ATDC5
chondrogenesis
Fibronectin Leucine Rich Transmembrane Protein
Leucine Rich Repeats
condensation
cell-ECM
fibronectin
extracellular matrix
Advisor: Gong, Siew-Ging
No Fault Found Reporting and its Relation to Human Factors Related Design Faults of Medical Devices

This research used human factors methods to investigate the relationship between no fault found (NFF) incident frequency and device usability. NFF reporting occurs when a medical device sent for repair is found to be operating normally. NFF incidents are one of the most recurrent failure modes, and therefore have considerable impact on cost, dependability and safety. An analysis of medical equipment maintenance data was conducted and six devices with a high NFF reporting frequency were identified. Semi-structured interviews and heuristics evaluations revealed that usability issues likely caused many of the NFF incidents. Other factors suspected to contribute to increased NFF reporting include accessory issues, intermittent faults and environmental issues. Finally, in order to validate the results, usability testing was conducted on three of the devices. 23 usability-related design flaws were identified. Therefore devices containing latent usability-related design flaws can be identified through analysis of medical equipment maintenance data.

Keywords: Human Factors
Clinical Engineering
Medical Device Design
No Fault Found
No Problem Found
No Trouble Found
Advisor: Cafazzo, Joseph
Computational Fluid Dynamics Analysis for Wastewater Floc Breakage in Orifice Flow

In the present work, the breakage of wastewater particles in orifice flow is investigated through numerical simulations. Using maximum strain rate along particle paths as the breakage criterion, breakage is predicted using computational fluid dynamics. The numerical simulations confirm that nominal orifice strain rate cannot explain the higher particle breakage in single-orifice systems compared to that of multi-orifice systems, instead particle breakage was found to correlate well with the maximum strain rates in the system. On the issue of effect of initial particle location on breakage, numerical modeling shows that particles travelling along the centerline are suspected to break less than those travelling near the wall. However, experiments designed to study the breakage of particles injected at various radial locations proved inconclusive. Finally, results suggest that while single orifice systems are ideal for strong particles, multi-orifice systems may be more effective in breaking weak particles.

Keywords: Orifice
Wastewater treatment
UV Disinfection
Particle Breakage
Computational Fluid Dynamics
Advisor: Farnood, Ramin
Lawryshyn, Yuri Andrew
Atmospheric Inversion of the Global Surface Carbon Flux with Consideration of the Spatial Distributions of US Crop Production and Consumption

Carbon dioxide is taken up by crops during production and released back to the atmosphere at different geographical locations through respiration of consumed crop commodities. In this study, spatially distributed county-level US cropland net primary productivity, harvested biomass, changes in soil carbon, and human and livestock consumption data were integrated into the prior terrestrial biosphere flux generated by the Boreal Ecosystem Productivity Simulator (BEPS). A global time-dependent Bayesian synthesis inversion with a nested focus on North America was carried out based on CO2 observations at 210 stations. Overall, the inverted annual North American CO2 sink weakened by 6.5% over the period from 2002 to 2007 compared to simulations disregarding US crop statistical data. The US Midwest is found to be the major sink of 0.36±0.13 PgC yr-1 whereas the large sink in the US Southeast forests weakened to 0.16±0.12 PgC yr-1 partly due to local CO2 sources from crop consumption.

Keywords: Atmospheric inversion
cropland carbon
crop production
crop consumption
carbon flux
US cropland
Advisor: Chen, Jing Ming
Novel Carbon-based Electrode Materials for Up-scaled Microfluidic Fuel Cells

In this work, a MFC fabrication procedure including two non-conventional techniques (partial baking and cap-sealing) were employed for the development of an up-scaled microfluidic fuel cell (MFC). Novel carbon-based electrode materials were employed, including carbon foam, fibre, and cloth, the results from which were compared with traditionally-employed carbon paper. The utilization of carbon cloth led to 15% of the maximum power that resulted from carbon paper; however, carbon fibre led to a 24.6% higher power density than carbon paper (normalized by electrode volume). When normalized by projected electrode area, the utilization of carbon foams resulted in power densities up to 42.5% higher than that from carbon paper. The impact of catalyst loading on MFC performance was also investigated, with an increase from 10.9 to 48.3 mgPt cm-2 resulting in a 195% increase in power density.

Keywords: Microfluidics
Fuel Cells
Renewable Energies
Microfabrication
Advisor: Bazylak, Aimy
Development of Novel Approach for In Situ Generation of Oxidative Stress using KillerRed in C. elegans

Oxidative stress has been implied in a wide variety of diseases, such as cancer, myocardial infarction, and neurodegenerative diseases including Parkinson's diseases (PD). PD is characterized by the degeneration of dopaminergic (DA) neurons; genetic studies have identified gene mutations causal to PD. Accumulating studies hypothesize that these genes protect DA neurons against oxidative stress. However, lack of experimental tools to target oxidative stress in specific cells has prevented direct evaluation of the hypothesis. We established a novel method to use KillerRed (KR), a genetically-encoded protein that generates radicals upon light activation. We showed its efficacy in live animals by cell-specific ablation of neurons in C. elegans. We applied KR to degenerate DA neurons. By controlling the level of stress via activation light, the protective role of PD-gene, LRRK2, against oxidative stress was confirmed. Thus, we established a method to address the role of oxidative stress in a cell-specific manner.

Keywords: Parkinson's disease
C. elegans
Optogenetic
KillerRed
Oxidative Stress
Genetics
Neurodegeneration
dopamine neurons
Advisor: Suzuki, Hiroshi
The Effect of Rotation on the Decellularization of Porcine Lungs

This thesis examines the challenges of decellularizing porcine lungs. The thesis identifies hydrostatic pressure and the role it plays in perfusate distribution within the lung as a potential roadblock for the decellularization of porcine lungs. The thesis examines methods for mitigating the affect of hydrostatic pressure on the decellularization of porcine lungs. Specifically, the thesis details the design and construction of a vessel that rotates lungs during decellularization. This rotating vessel is evaluated in comparison to two other, non-rotation based, decellularization methods. The rotation device is found to more extensively decellularize the lung than either of the other two options. The thesis concludes by examining what other areas of work could be conducted in this field.

Keywords: Decellularization
Lung
Porcine
Rotation
Advisor: Waddell, Thomas K.
Analysis of Visual Scanning Behaviours for the Objective Assessment of Psychiatric Disorder

Biases in selective information-processing or attention biases are features of most psychiatric disorders. Attention biases can be measured by monitoring visual scanning behaviour (VSB) which is directly linked to attention allocation processes. This thesis presents a general framework for studies of VSB when multiple images are presented simultaneously to the viewer. Within this general framework, a novel set of VSB parameters that characterize the different stages of the visual scanning process was developed. Using this set of parameters, biases towards thin and fat body shape images were detected in Anorexia Nervosa patients. A log-likelihood ratio detector utilizing VSB parameters had both high sensitivity (92%) and high specificity (90%). Preliminary results in VSB studies also show biases in adults with Major Depressive Disorder and elderly apathetic Alzheimer’s patients. The development of sensitive physiological markers in individuals with mental illness is crucial to the advance of research, diagnosis, and treatment in psychiatry.

Keywords: visual scanning
anorexia nervosa
Advisor: Eizenman, Moshe
The Effects of CREB-mediated BDNF Expression on Memory- and Anxiety-related Behaviours in the Adult Mouse

Experience drives changes in gene expression that mold and reorganize neuronal circuits. In response to neuronal activity, the transcription factor CREB binds to a regulatory site on Bdnf promoter IV to modulate BDNF protein levels. CREB and BDNF are extensively implicated in animal behaviour, but the role of the interaction between these proteins has not been studied. I used transgenic mice carrying mutations at the CREB binding site of Bdnf promoter IV (CREmKI mutation) to specifically disrupt this interaction. F1 (N = 52) and F2 (N = 69) mice underwent a battery of behavioural tests. All mice showed normal motor learning and spatial memory. Critically, F1 mutants showed impaired auditory fear memory, while F2 mutants showed heightened anxiety. I suspect that differences in Bdnf expression and compensatory effects contributed to discrepancies between the two generations. My findings highlight the relevance of BDNF expression levels for memory- and anxiety-related behaviours.

Keywords: transgenic mice
memory
anxiety
motor learning
fear conditioning
water maze
CREB
BDNF
behaviour
activity-dependent
Advisor: Josselyn, Sheena
Quality-of-service for Network-on-chip-based Smartphone/Tablet Systems-on-chip

Smartphone/tablet Systems-on-Chip (SoCs) integrate increasing number of components to offer more functionality. Capacity and efficiency of data communication between memory and other hardware blocks have become a major concern in the SoC design. To address this concern, we propose to use Network-on-Chip (NoC) architectures, to meet high bandwidth, and low power and area demands. We propose a Quality-of-Service (QoS) scheme to differentially provision network resources to cater to different performance requirements by different hardware blocks. Implementation and evaluation are performed on a simulation infrastructure we construct specifically for this type of SoCs. We demonstrate, via simulation results, that the proposed Dynamic QoS schemes can achieve better bandwidth provisioning, with good area and power efficiencies.

Keywords: Quality-of-Service
Network-on-Chip
Smartphone SoC
Advisor: Jerger, Natalie Enright
A Study of Fibre-matrix Interactions in Biodegradable Kraft Pulp Fibre-reinforced Polylactic Acid Composites

As the plastics sector moves towards sustainable growth and development, natural fibres start to play an important role as constituents in composite materials in several industries including automotives. However, drawbacks such as fibre-matrix incompatibility and poor fibre dispersion still exist. In this thesis, Kraft pulp fibre (KF)-Polylactic Acid (PLA) composites were prepared using thermal compounding and aqueous blending to study fibre-matrix interactions. Fibre surfaces were also modified to improve fibre dispersion and water absorption properties. A biorefinery lignin was added to PLA and high density polyethylene (HDPE) as a biofiller and potential interface modifier. Aqueous blended composites showed better mechanical and dynamic mechanical performance than the thermally compounded materials. The fibre surface modification improved dispersion and material properties at higher fibre content. Furthermore, the addition of lignin to polymers resulted in improved mechanical properties in both PLA and HDPE; however, lignin failed to improve interface bonding between KF and PLA.

Keywords: Biocomposite
Natural fibre reinforcement
Polylactic acid
Lignin
Advisor: Yan, Ning