VictorJuiz/thesis huggingface dataset:
Genetic Modifiers of Caffeine Consumption and Risk of Myocardial Infarction
Keywords: Caffeine
Gene-Environment Interaction
Myocardial Infarction
Coffee
HTR2A
DRD2
Serotonin Receptor 2A
Dopamine D2 Receptor
Polymorphism

The variability in caffeine consumption and inconsistencies among studies linking caffeine to heart disease may be explained by genetic variation. Caffeine antagonizes adenosine receptors with downstream effects on dopamine and serotonin. The objectives of this thesis were to determine whether the DRD2 957C>T or HTR2A 102C>T polymorphisms are associated with caffeine consumption or modify the association between coffee consumption and risk of myocardial infarction (MI). DRD2 genotype was associated with caffeine consumption among non-smokers and CYP1A2 -163C allele carriers. HTR2A genotype was associated with caffeine consumption among non-smokers and subjects with the ADORA2A TT genotype. Neither polymorphism modified the association between coffee consumption and risk of MI; however, a significant coffee x HTR2A interaction was seen among subjects with the CYP1A2 -163C allele. The results suggest caffeine’s reinforcing effects may be mediated by the dopamine and serotonin receptors and implicate serotonin in caffeine’s effect on risk of MI.
Topics in Designing Low Thermal Expansion Lattices at the Microscale
Keywords: Low Thermal Expansion Lattices
Amorphous Materials
Molecular Dynamics
Nanoindentation

Microscale bi-material lattices with near zero thermal expansion are designed to create a thermally stable optical surface for applications in a space telescope. To facilitate the design, the thermal expansion of a unit cell with spacers is derived analytically and validated via finite element studies. Predicting the lattice behaviour also requires knowledge of the constituent properties. To this end, molecular dynamics simulations are performed to determine the thermal expansion and recrystallization behaviour of aluminum and titanium thin films, and nanoindentation experiments are conducted to extract their elastic-plastic properties. Unit cell configurations giving near zero thermal expansion are obtained through iterative analysis. The resulting designs are analyzed and validated via finite element simulations and shown to exhibit long term stability.
Investigating the Role of Alternative Oxidase in Nicotiana tabacum during Light Acclimation
Keywords: Alternative oxidase
Photosynthesis
Respiration
Nicotiana tabacum
Chloroplast-mitochondrion relationship

Photosynthetic electron transport produces ATP and NADPH which support carbon fixation by the Calvin Cycle. To avoid over-reduction of the electron transport chain, plants must balance absorption and consumption of light energy. Mitochondrial alternative oxidase (AOX) is a non-energy-conserving electron sink, making it an ideal candidate to oxidize excess reductant and regulate chloroplastic redox state. Wild-type (WT) and transgenic Nicotiana tabacum lines with enhanced or suppressed AOX protein levels were grown under low light (LL) and moderate light (ML). LL-grown plants were also shifted to ML. AOX transcript and protein levels were enhanced in WT plants under ML. Chlorophyll fluorescence, gas exchange, and contents of chlorophyll, carbohydrate, and malondialdehyde were measured. Lack of AOX protein decreased Photosystem II (PSII) quantum efficiency and CO2 assimilation rates while enhancing PSII excitation pressure compared to WT. These findings suggest a role for AOX in mediating the chloroplast-mitochondrion relationship during acclimation to higher irradiance.
Experimental Study of the Microstructural Evolution of Chemical Vapor Deposited (CVD) Nickel upon Annealing
Keywords: CVD nickel
detwinning
five-fold twinned particles
bi-modal grain size distribution
Chemical vapor deposition

The effect of annealing conditions on the microstructure evolution of CVD nickel was investigated systematically in the present study by differential scanning calorimetry, optical microscopy and transmission electron microscopy (TEM), upon both ex-situ and in-situ annealing. TEM observation revealed the as-deposited CVD nickel possessed a bi-modal grain structure, with large columnar grains embedded in nanocrystalline matrix. Ultrafine and nano growth twins were present as well as multiply twinned grains with five-fold symmetry. Microstructure observation upon annealing showed that grain growth did not occur until annealing at 400ºC. Detwinning was observed at 400ºC and higher temperatures. The ultrafine and nano twins tended to transform into dislocation cell structures and this phenomenon was driven by the excess free energy associated with the high density of grown-in twin boundaries. The five-fold twinned grains were found to be thermally stable up to 600ºC. The hardness was observed to decrease with increasing annealing temperature.
Foot Placement Patterns of Individuals with Multiple Sclerosis during Rollator-assisted Community Mobility
Keywords: rollator
multiple sclerosis
gait
mobility

Individuals with Multiple Sclerosis commonly use assistive mobility devices, such as rollators, to compensate for their mobility impairments. However, the effect of these devices on their foot placement during gait has not been explored in the community. The objective of experiment one was to develop and validate a tool that quantifies medio-lateral foot placement characteristics during rollator use. In this study, a technique was developed for an instrumented rollator (i.e. iWalker) and validated against a Vicon motion capture system in able-bodied young adults. The two systems were in strong agreement. The objective of experiment two was to apply this iWalker-based technique to individuals with Multiple Sclerosis to identify environment-related foot placement changes. This study revealed that step width variability, but not step width, can be influenced by certain outdoor environments. Therefore, environmental context is important to consider when investigating user-device interactions and factors responsible for safe mobility in this population.
Modulation of T Cell Function by Coagulation Factor Xa
Keywords: Immunology
Coagulation
T Cell Biology
Protease Activated Receptors
Factor Xa

The serine protease factor Xa (FXa) plays an integral role in the coagulation cascade and has recently been implicated in a variety of proinflammatory roles, establishing it as a link between coagulation and inflammatory processes. In this thesis, I elaborate on previous literature by characterizing further the response of primary human T lymphocytes to FXa. Building on previous literature that describes the effect of FXa on whole T cell populations, I describe here the effect of FXa on both antigen-independent and antigen-dependent proliferation and costimulation of primary CD4+ and CD8+ T cells, thereby establishing an immunological role for FXa. Further, I show that FXa elicits an immediate and direct effect on T cells demonstrated by the rapid upregulation of the signalling cascade kinases, ERK1 and ERK2. Lastly, I demonstrate that the protease activated receptor 2 (PAR2) is involved in the mediation of this direct FXa effect.
The Expression Profile of KIAA0319-like in Chick Embryos and its Involvement in Cell Migration in the Developing Optic Tectum
Keywords: cell migration
optic tectum
neuroscience
dyslexia

Several genes thought to confer susceptibility to dyslexia have been identified, and the purpose of this study is to 1) determine the expression pattern of one of these gene products and 2) characterize the function of the product of one of these genes, namely KIAA0319-Like (KIAA0319L), using the developing chick visual system as a model. Whole mount in situ hybridization was performed for KIAA0319L on embryonic day (E)3 – E5 and in situ hybridization on sections was performed at later stages. Engineered microRNA (miRNA) constructs targeting KIAA0319L were prepared and their specificity and efficiency for knocking down KIAA0319L were tested. miRNAs were electroporated in E5 optic tecta (OT). Embryos were sacrificed at E12. OT were removed, sectioned and analyzed. Results demonstrate that KIAA0319L is expressed in the developing chick visual system. Knockdown of KIAA0319L in the OT results in abnormal migration indicating that KIAA0319L is necessary for this process.
Electroanalysis of α-Synuclein Aggregation Related to Parkinson's Disease
Keywords: Parkinson's Disease
Electrochemistry
Alpha-synuclein
Baicalein
Dopamine
Metal

The main goal of this research is to provide a novel bioanalytical approach to better understand α-synuclein (AS) aggregation linked to Parkinson’s disease (PD) and characterize the implications of contributing factors such as the presence of metal ions and potential therapeutics that would inhibit or reverse AS fibrillation. Current bioanalytical techniques have reported the fibrillation process of AS however, the detection of prefibrillar formation or the nucleation phase of AS has yet to be characterized. This research aimed to address this issue and monitor the primary stages of AS fibrillation from natively soluble monomer to fibrillar aggregates. The electrochemical measurement of these processes utilized the intrinsic electroactivity of 4 tyrosine (Tyr) residues in AS observed at ~0.6 V (vs. Ag/AgCl) to monitor its early fibrillation kinetics. The research presented here provided valuable evidence of the conformational changes attributed to prefibrillar forms of AS.
Aromatic Hydrocarbon Sampling and Extraction From Flames Using Temperature-swing Adsorption/Desorption Processes
Keywords: Polycyclic aromatic hydrocarbons
Diffusion flames
Adsorption sampling
Measurement technique

The measurement of Polycyclic Aromatic Hydrocarbons (PAHs) in flames is essential for the understanding of soot formation. In comparison to conventional aromatics-sampling techniques, a new technique was proposed that involves fewer manual operations and no hazardous extraction solvents. Apparatus and experimental procedures of the newly proposed adsorptive-sampling and desorptive-extraction technique for aromatic-hydrocarbon measurements were established in this study. The capabilities and limitations of this new technique were assessed in terms of limits of detection, sampling locations and data repeatability. The accuracy of this technique was also evaluated. Aromatic-hydrocarbon species concentrations were measured in laminar co-flow diffusion flames of ethylene (C2H4) and synthetic paraffinic kerosene (SPK). The results obtained from the ethylene flame were compared to its numerical simulation, with the goal of achieving agreement within an order of magnitude. The differences between simulated values and experimental measurements, along with the limitations of the technique, were used as an indication of the accuracy of the technique.
Microstructural and Mechanical Characterization of Multilayered Iron Electrodeposits
Keywords: Iron electrodeposition
Multilayered coating
Microstructure
Microhardness

Multilayered iron electrodeposits composed of alternating layers of coarse-grained iron (grain size: 1.87 μm; (110) texture; hardness: 177 VHN) and fine-grained iron (grain size: 132 nm; (211) texture; hardness: 502 VHN), with layer thicknesses ranging from ~0.2-7 μm were successfully synthesized. The average hardness of the multilayered electrodeposits increased from 234 VHN to 408 VHN with decreasing layer thickness, consistent with a Hall-Petch type behaviour. In three-point bending tests, they failed in a macroscopically brittle manner although local ductility was observed in certain layers. Fractography analysis has shown that strain incompatibility between alternating layers contributes to the brittle nature of these materials. This study has demonstrated the possibility of applying a multilayered structure design to tailor the microstructure and mechanical properties of electrodeposited iron.
Thermal Management for Multi-phase Current Mode Buck Converters
Keywords: Thermal Management
DC-DC Power Converters
Multi-Phase
Current Mode
Digital Control
Switched Mode Power Supplies
Buck Converters

The main goal of this thesis is to develop an active thermal management control scheme for multi-phase current mode buck converters in order to improve the long term reliability of the converters. A thermal management unit (TMU) with independent linear compensators for the thermal loops is incorporated into the existing digital controller to regulate the current through each phase so that equal temperature distribution is achieved across all phases. A lumped parameter thermal model of the multi-phase converter is built as the basis of the TMU. MATLAB simulation results are used to verify the TMU concept. Experimental results from a digitally controlled 12 V to 1 V, 50 A, 250 kHz four-phase peak current mode buck converter demonstrate the effectiveness of the proposed thermal management technique in the presence of uneven air flow. The steady-state performance, dynamic transient load performance, effect of gate drive voltage and efficiency measurements are investigated and discussed.
Genetic Variability in Caffeine Acute Effects and Withdrawal Symptoms
Keywords: caffeine
COMT
DARPP-32
PPP1R1B
nutrigenomics

The mechanisms underlying caffeine’s acute effects and withdrawal symptoms are not entirely understood. The purpose was to determine whether the clusters of acute effects or withdrawal symptoms are associated with genetic polymorphisms in DARPP-32 and COMT, which mediate some of caffeine’s physiological effects. Subjects (n=1135) were from the Toronto Nutrigenomics and Healthy Study. Fourteen well-described acute effects of caffeine co-exist in six groups, while fourteen well-characterized withdrawal symptoms co-exist in three groups. Neither the rs907094 C>T polymorphism in the PPP1R1B gene encoding DARPP-32, nor the COMT Val158Met affected the odds of reporting any acute effects or withdrawal symptoms cluster. Among individuals consuming ≥ 200 mg/d of caffeine, Met/Met homozygotes were more likely to report the “increased heart rate” acute effects cluster. These results suggest that ‘slow’ COMT activity, conferred by the Met allele, may explain part of the inter-individual variability in the risk for increased heart rate among heavy caffeine consumers.
The Biogeography of Peel's Urban Forest: Patterns and Correlates of Species Diversity
Keywords: urban forestry
urban biogeography
species richness
land use
socioeconomics

The purpose of this research project is to identify the species-level diversity and distribution of trees within the urban setting of Peel Region (Ontario, Canada) and to determine how these characteristics change as a function of land use type. To address this, alpha diversity (species richness within a community), evenness, and beta diversity (species richness between communities) were calculated for eight distinct land use types within the study area. As well, the influence that a variety of socioeconomic and urban form variables have in determining urban forest composition was examined using regression techniques. Results indicate that significant relationships exist between land use type, species richness and overall tree abundance. Variables reflecting wealth and urban form are also shown to significantly influence tree abundance. The results of this study address issues pertaining to the adaptation, conservation, and management of the region’s urban tree species.
Label-free, Direct Detection of Cocaine using an Aptamer in Conjunction with an Ultra-high Frequency Acoustic Wave Sensor
Keywords: acoustic
biomedical engineering
cocaine
piezoelectric
biosensor
self assembled monolayers
thickness shear mode
anti-cocaine aptamer
aptasensor
Electromagnetic piezoelectric acoustic sensor
TSM
EMPAS
aptamer immobilization optimization
label-free cocaine detection

This study embarks on exploiting the Thickness Shear Mode (TSM) acoustic wave sensor and the ElectroMagnetic Piezoelectric Acoustic Sensor (EMPAS) towards the study of aptamer-to-cocaine binding in a label-free direct approach. The high sensitivity and selectivity offered by the EMPAS in combination with alkyltrichlorosilane-based self-assembled monolayers proved superior towards the detection of cocaine. The most efficient method for the attachment of the aptamers onto the sensor surface to construct highly dense populations of the aptamer molecules with retained biomolecule activity is shown to be dependent on the composition of immobilizing solution and on the amount of spacing provided in the plane of the aptamer molecules. The distinct ligand-induced binding mechanisms and regeneration capabilities of the two anti-cocaine aptamers are monitored with the EMPAS. Utilizing this sensor to monitor cocaine-aptamer interactions will serve as the first piezoelectric aptasensor for the detection of a small molecule.
The Use of End Plates for a Cylinder in the Sub-critical Flow Regime
Keywords: Cylinder, Flow, Sub-critical, regime, end plates, PIV

Experiments were conducted in a free-surface, re-circulating water channel to determine the dependence of spanwise flow uniformity in the near wake of a circular cylinder on the end conditions using Particle Image Velocimetry. The Reynolds number was 10,000. The end conditions consisted of plates with different leading edge geometries and configurations. A cylinder bounded by two endplates with sharp leading edge geometry generated the most uniform near wake. The horseshoe vortex dynamics in the cylinder/ wall and cylinder/endplate junctions were also studied. Upstream flow separation significantly altered the behavior of the horse shoe vortices. Periodic horse shoe vortex oscillation was found for experiments with the upstream flow attached; this periodic oscillation was disrupted with the presence of upstream flow separation. The endplate leading edge distance was also investigated. The oscillation frequency of the horse shoe vortex system was found to decrease with increasing leading edge distance.
Effect of High Yield Pulp on the Dimensional Stability of Wood-free Paper for Inkjet Printing Applications
Keywords: Dimensional Stability
Cockling
High Yield Pulp
Inkjet Printing
Hygroexpansivity
X-ray microtomography

A hygroexpansimeter, cockling tester and a novel x-ray microtomography technique were employed to characterize hygroexpansivity as well as macro- and micro-scale cockling of wood-free paper sheets containing varying amounts of aspen high yield pulp (HYP) in order to validate its potential applicability in inkjet printing. Results from the hygroexpansimeter confirm previous findings that substitution levels of 30% and above lead to a slight deterioration of hygroexpansivity; however, contrary to the expected outcome, aspen HYP did not necessarily result in a higher tendency to form cockles. In fact, a comparison of the cockling behaviour between various paper samples and commercial paper substantiates that up to 40% of aspen HYP can replace hardwood bleached Kraft pulp. The preservation of out-of-plane dimensional stability in non-coated samples is most likely due to the increase in bending stiffness of the paper as it became bulkier with more aspen HYP.
The Effects of Self-evaluation Training on Writing of Students in Grades 5 & 6
Keywords: Self-Evaluation
Self-Assessment
Authentic Assessment
Formative Assessment
Assessment for Learning
Self-Regulated Writing
Criterion-based Feedback
Self-Evaluation Training

The purpose of this action research is to discover how self-evaluation training affects students’ knowledge and understanding about their writing and needs for improvement. In this study of 46 fifth and sixth graders, students underwent a four-stage self-evaluation training process. This involved students in defining criteria for their stories, teaching them how to apply the criteria using a variety of samples, giving students feedback about their self-evaluations, and developing action plans The study showed that after the self-evaluation process was set into place, students had an increased awareness of what made a good fictional writing piece. The self-evaluation process helped students become more aware of writing practices and of themselves as a writer. The study also found that the self-evaluation process set clear guidelines for students, focused student attention on important writing criteria, and opened up the conversation between students and teachers about evaluation, goal setting and the writing process.
Building a Community of Learners amongst Under-performing Students in Literacy through the use of a Book Club
Keywords: Literacy
Reading
Writing
Under-Achieving
Book Club
Community of Learning
Student Performance
Reading as a Social Act
Writing as a Social Act
Elementary
Social Performance

This study examines the effectiveness of a community of learning, through a book club, on student performance for students underachieving in literacy. This first chapter introduces the study, the researcher and how they are situated within the research, and the context and rationale of the study. The second and third chapters detail current research in literacy, learning, and communities of learning. They detail the methodological approach and rationale. The fourth and fifth chapters explain what took place during the study, what it means, and why this is important for teachers and teacher practice. Despite its limitations, this study finds that communities of learning, established through a book club, positively affect both academic and social performance. Book clubs create interconnectedness between its members that increases student engagement, which increases the amount of authentic dialogue. From this, book club members collaboratively co-construct knowledge resulting in general improvement, both academically and socially.
Responsiveness to Culture: Conflict Management Practices of Secondary School Administrators
Keywords: conflict management
cultural responsiveness
cultural proficiency
discipline
administrators

Traditional administrative approaches to conflict in schools tend to be punitive, dominated by Western cultural assumptions, and to disregard students’ cultures. Cultural responsiveness attends to different worldviews while appreciating the impact of one’s own cultural lens. This thesis applies a cultural proficiency framework to analysis of the conflict management practices of administrators in secondary schools in a south-central Ontario school board. Analysis of data from interviews with secondary school administrators, students, school board cultural community liaisons, and school board documents indicate that culturally proficient cross-cultural interactions between administrators and students tended to include relationship-building efforts aimed at learning from and about disputants. In contrast to typical punitive and uncommunicative approaches, cultural proficiency was evident in some elements of alternative participatory or restorative approaches. In combining cultural proficiency with conflict management, this thesis helps to fill a gap in research relevant to equitably serving diverse student populations in southern Ontario schools.
An Analysis of L2 Article Use in English
Keywords: L2 Article Use
Definite Article

This paper is a partial replication study of research to investigate an aspect of English articles: the acquisition of 4 nongeneric uses of the definite article in English. Analysis of article use in these four categories (i.e. cultural, situational, structural, and textual) was investigated by Liu and Gleason (2002), and a hierarchy of difficulty and acquisition was proposed based upon the initial results. This partial replication used the same testing instrument as Liu and Gleason (2002) with additional items included to further investigate the category, cultural use of the article. The participants, 17 low-intermediate, 20 high-intermediate, and 34 advanced ESL learners completed a 100 item test with sentences containing deleted obligatory uses of the as well as distractor items. The results partially supported Liu and Gleason‟s original study, and raised many concerns with the test instrument.