VictorJuiz/thesis huggingface dataset:
The Development of a Laser-induced Incandescence System
Keywords: Laser-Induced Incandescence
LII
soot diagnostics

The ability to accurately measure solid particulate levels in various applications ranging from engines to laboratory flames has become very important in the past few decades. A new approach to measuring soot levels called laser-induced incandescence was investigated. An apparatus was designed and built in order to measure soot levels in an atmospheric laminar diffusion flame with the intent of conducting proof-of-concept measurements. The apparatus utilized highly focussed optics while collecting time-resolved data using fast PMTs which allowed measurement of both time and spatial domains. Although noise and other technical problems proved to be a concern, measurements with reasonable agreement with published results for temperature (2800 K) and the primary particle soot size (6.3 +/- 2.5 nm) were achieved within the flame. Noise issues with the apparatus prevented accurate soot volume fraction measurements from being obtained. Numerous suggestions have been made as to how to improve the experiment for future use, potentially in a high pressure environment.
The Role of Hepoxilins in an Asthma-like Mouse Model
Keywords: Hepoxilins
Asthma

Asthma is a chronic respiratory illness where the airway occasionally constricts, becomes inflamed, and is lined with excessive amounts of mucus. There are many lipid mediators involved in this inflammatory response. Hepoxilins are biologically active hydroxyepoxy eicosatrienoic acid metabolites of arachidonic acid, formed through the 12-lipoxygenase pathway. Our goal in this study was to identify if hepoxilins had a direct effect on smooth muscle contractions, to identify the source of hepoxilins in asthmatic-like mouse model, and to determine if blocking this pathway reduced inflammation associated with ovalbumin sensitization. We found that hepoxilins had no direct effect on smooth muscle contraction. We identified the bronchiolar epithelium as a major source of hepoxilins in OVA-challenged mice. We demonstrated that baicalein inhibits total lung resistance in the OVA-treated mice, but also found that the drug in-vivo is not specific for 12-lipoxygenase.
Neurophysiological Correlates of Self-monitoring Differentially Moderate the Relation Between Maternal Depression and Children's Behaviour Problems
Keywords: Neuroscience
Developmental Psychology

Research in developmental psychopathology has advanced our understanding of emotional dysregulation underlying children’s behavioural problems and their association with maternal depression. Neurophysiological measures may further clarify these relations. The ERN (error-related negativity) is an event-related potential commonly used to assess self-monitoring, with large amplitudes reflecting internalizing and small amplitudes reflecting externalizing symptoms. The present study investigated the effect of ERN amplitude on the relation between maternal depression and internalizing and externalizing problems in a sample of children referred for aggressive behaviour. ERN amplitudes were recorded while 50 children (8-10 years of age) engaged in a go/no-go emotion induction task. Results indicated an association between high ERN amplitudes and internalizing behaviour and between small ERN amplitudes and externalizing behaviours for children with depressed mothers. These findings suggest that the degree of self-monitoring (indexed by ERN amplitude) moderates the relation between maternal depression and psychopathological outcomes in children.
Mexican-American Parents’ Working Hours, Parental Involvement, and Adolescent Academic Achievement
Keywords: parental work hours
Mexican-American students
parental involvement
academic achievement
generational differences

In order to better understand the specific mechanisms that may hinder high educational achievement among Latino students, this study explored the impact of parental working hours on parental involvement and school outcomes across three generations of Mexican-American youth. Results from a longitudinal data set revealed that constrained parental availability, related to increased working hours, had an impact on the amount of parental involvement for third generation students, but not on their academic outcomes. For first-generation students, parental monitoring (a form of parental involvement) was a significant positive predictor for grade 8 and 10 reading scores as well as high school completion among second-generation students. Results from this study suggest that increased parental monitoring may be beneficial for higher academic outcomes for first and second generation students. Future research will need to investigate what types of parental involvement may influence third generation students.
Musculoskeletal Injury in Professional Dancers: Prevalence and Associated Factors. An International Cross-sectional Study
Keywords: Occupational Health and Safety
Dance

Abstract Purpose: To determine the prevalence and factors associated with injury in professional ballet and modern dancers, to explore dancers’ attitudes and perceptions of injury, and to assess if dancers are reporting their injuries and reasons for not reporting injuries. Methods: A cross-sectional survey was undertaken in professional ballet and modern dance companies in Canada, Denmark, Israel, and Sweden. Results: The point prevalence of injury in dancers is high (55% ballet; 46% modern) and most have chronic pain. Years dancing professionally and rank were associated with injury in ballet dancers. Attitudes towards injury vary and some dancers are continuing to dance when injured. Greater than 15% of all injured dancers have not reported their injury. Conclusions: Injury is common in dancers and there is an urgent need to investigate interventions to help control injury and understand the long-term implications of these conditions in this population.
The Presynaptic F-box Protein FSN-1 Regulates Synapse Development via Retrograde Insulin Signaling in Caenorhabditis elegans
Keywords: Synaptogenesis
Insulin Signaling
FSN-1

Synaptogenesis entails the development and establishment of functional synapses, which form the fundamental unit of communication in the nervous system. Initially identified in Caenorhabditis elegans (C. elegans), the FSN-1, F-box protein family has emerged as evolutionarily conserved binding partners of PHR family proteins, which regulate synaptogenesis. Previously, we have shown that FSN-1 and RPM-1 form a SCF/FSN-1/RPM-1 ubiquitin ligase complex that negatively regulates synapse growth by downregulating presynaptic targets, like the MAP kinase pathway. For my master’s thesis, I used a combination of both candidate and forward genetic approaches to identify additional components of signaling pathways that are regulated by FSN-1 during synaptogenesis. Our studies are among the first to suggest diverging roles for these partners and provide the first evidence for a mechanism through which the F-box protein regulates synaptogenesis via retrograde insulin/IGF/FOXO signaling and glucosaminidase/O-GlcNAc modifications.
Quantifying the Effects of Radiation on Tumour Vasculature with High-frequency Three-dimensional Power Doppler Ultrasound
Keywords: Ultrasound
Power Doppler

Recent evidence suggests that radiation may have a significant effect on tumour vascu lature in addition to damaging tumour cell DNA. It is well established that endothelial cells are among the first cells to respond after administration of ionizing radiation in both normal and tumour tissues. It has also been suggested that microvascular dysfunction may regulate tumour response to radiotherapy at high doses. However, due to limitations in imaging the microcirculation this response is not well characterized. Advances in high-frequency ultrasound and computation methods now make it possible to acquire and analyze 3-D ultrasound data of tumour blood flow in tumour micro-circulation. This thesis outlines the work done to test the hypothesis that single dose 8 Gy radio- therapy produces changes in tumour blood vessels which can be quantified using high- frequency power Doppler ultrasound. In addition, the issue of reproducibility of power Doppler measurements and the relationship between histopathology and power Doppler measurements have been examined.
The Impact of Lesser Snow Goose Herbivory on Above and Belowground Nutrient Dynamics in Two Sub-Arctic Ecosystems
Keywords: lesser snow geese
microbes
rhizosphere
nitrogen

In order to determine the impact of lesser snow goose (Chen caerulescens caerulescens) herbivory on above and belowground nutrient dynamics, a grazing and nutrient addition experiment was conducted in two habitat types utilized by snow geese near Churchill, Manitoba. Forage plant nutrition, soil microbial biomass, and inorganic and organic soil nutrients were measured in relation to the timing of grazing, over two consecutive summers. Soil was collected from the rhizosphere to determine the influence of foliar herbivory on root-microbe interactions. Primary productivity in both habitats is co-limited by the availability of both nitrogen (N) and phosphorus (P). Aboveground defoliation either caused a reduction or no change in soil microbial biomass nutrients (carbon (C), N, or P). Defoliated shoots had higher N concentrations and did not show compensatory growth within the season. Root biomass was somewhat reduced with grazing, but higher whole plant N content suggests that grazing does not compromise N-uptake.
Cut Once, Measure Everywhere: The Stability of Percentage of Students Above a Cut Score
Keywords: large-scale assessment
standardized tests
cutting score
measures
accountability
student improvement
academic achievement
school trends
EQAO
statistics

Large-scale assessment results for schools, school boards/districts, and entire provinces or states are commonly reported as the percentage of students achieving a standard – that is, the percentage of students scoring above the cut score that defines the standard on the assessment scale. Recent research has shown that this method of reporting is sensitive to small changes in the cut score, especially when comparing results across years or between groups. This study extends that work by investigating the effects of reporting group size on the stability of results. For each of ten group sizes, 1000 samples with replacement were drawn from the May 2009 Ontario Grade 6 Assessment of Reading, Writing and Mathematics. The results showed that for small group sizes – analogous to small schools – there is little confidence and that extreme caution must be taken when interpreting differences observed between years or groups.
Quantitative Evaluation of Simulated Enamel Demineralization and Remineralization Using Photothermal Radiometry and Modulated Luminescence
Keywords: Artificial enamel caries
photothermal radiometry
modulated luminescence
demineralization
remineralization
quantitative diagnostics

Detection modalities that can evaluate the early stages of dental caries are indispensable. The purpose of this thesis is to evaluate the efficacy of photothermal radiometry and modulated luminescence (PTR-LUM) to non-destructively detect and quantify simulated enamel caries. Two experiments were performed based on the PTR-LUM detection mode: back-propagation or transmission-mode. Artificial demineralized lesions were created in human molars and a subset was further exposed to an artificial remineralizing solution. PTR-LUM frequency scans were performed periodically during de/re-mineralization treatments. PTR data was fitted to a theoretical model based on optical and thermal fluxes in enamel to extract opto-thermophysical parameters. Lesion validation was performed using transverse microradiography (TMR). Optical and thermal properties changed with the development and repair of the caries lesions while theory-derived thicknesses paralleled those determined microradiographically. These trends coupled with the uniqueness-of-fit of the generated parameters illustrate the efficacy of PTR- LUM to non-destructively detect and quantify de/re-mineralized lesions.
Assessing the Natural Variability in the Fish Communities of the Lakes of the Northern Bruce Peninsula
Keywords: Bruce Peninsula
aquatic ecology
community ecology
fish communities

To monitor and assess direct anthropogenic impacts on an aquatic system requires knowledge of its natural variation. The goal of this study explored natural variation in the lake fish communities of the northern Bruce Peninsula, which may act as a reference condition for other studies. The results of this study indicated there has been a shift towards more small-bodied, native species present in the fish communities, potentially a result of beaver activity in the area. A second goal was to calculate gear sampling efficiencies to enable the design of efficient monitoring protocols for fish communities in small, shallow lakes. It was concluded that a wide variety of gears are required to assess the fish species composition in a lake. Fine-mesh hoops were the most effective gear; however, saturation was never obtained for boat electrofishing; therefore, additional research is required to determine effectiveness relative to the fine-mesh hoop net.
Molecular Phylogeny of the Snake Genus Oligodon (Serpentes: Colubridae), with an Annotated Checklist and Key
Keywords: Evolutionary Biology
Phylogeny
Oligodon

The snake genus Oligodon, known for its egg-eating feeding behaviour, is a taxonomically and systematically challenging group from South and Southeast Asia. This work provides the first phylogenetic hypothesis for the genus, and includes a checklist and key to the species. I use approximately 1900 base pairs of mitochondrial DNA sequence data to infer the relationships of these snakes, and I examine congruence between the molecular phylogeny and hemipenial characters. A hypothesis for the position of Oligodon within the Colubridae is also proposed. I discuss the implications of the phylogeny for previous taxonomic groupings, and consider the usefulness of the trees in analysis of behaviour and biogeography.
Detecting changes in fish communities in response to habitat rehabilitation: a comparison of multimetric and multivariate approaches
Keywords: Index of Biotic Integrity
multivariate
bioassessment
fish community

Bioassessment can be performed through several methods and with different bioindicators. In Canadian Areas of Concern (AOC), fishes are used as a proxy for site condition. The Index of Biotic Integrity (IBI), a multimetric index for biological assessment, has been applied to fish data across Canadian AOCs to detect recovery. Previous studies, however, have indicated the IBI is not sensitive to assemblage changes characteristic of later stages of recovery. In this study, the IBI and multivariate methods were applied to data from two AOCs, the Detroit and St. Clair rivers. The results revealed that the IBI is susceptible to species substitutions within metric categories. The substitutions produced high variability within narrative ranks and rendered the IBI insensitive to changes, detected by multivariate methods, in the fish assemblage. In the absence of reference sites, the multivariate analyses were supplemented with the development of a reference condition based on best professional judgment.
A Framework for the Protection of Privacy in an Electronic Health Environment
Keywords: privacy
electronic health record

This paper argues that given the proliferation of electronic health records (EHRs) in the health care system, legislative reform must occur to address the inadequacies of Ontario’s current health privacy legislation in accommodating EHRs. A coherent framework for legislation is necessary to capture the important role that privacy plays in public perception when it comes to legislating and managing EHRs in Ontario and, in turn, serve as a tool for legislators to understand the definitions and values of privacy associated with EHRs and the privacy problems worthy of protection in an electronic health environment. The failure to properly address these problems may lead to privacy losses and loss of public confidence in EHR systems. In applying this framework to three legislative options, it is evident that Ontario should amend the Personal Health Information Protection Act, 2004 to better contemplate the privacy protections necessary in an electronic health environment.
Investigation of the Protein Components of the Zebra Mussel (Dreissena polymorpha) Byssal Adhesion Apparatus
Keywords: Zebra mussel
byssus
DOPA
Foot proteins
MALDI
FTIR

The byssal adhesion mechanism of the biofouling species Dreissena polymorpha was investigated using a combination of studies on synthetic peptide mimics of tandem repeat sequences from byssal component Dreissena polymorpha foot protein 1 (Dpfp-1) and characterization of the regions of the byssus. A 20-residue fusion peptide incorporating two Dpfp-1 repeat sequences adopts a random coil and β-turn conformation in solution, and spontaneously forms a film at the solid-liquid interface in the presence of iron (III) cations. Infrared characterization of the byssus Amide I region showed that β-sheets dominate its secondary structure, although the proportion of different secondary structures varies between regions. Matrix-assisted laser desorption ionization (MALDI) mass spectrometry of intact byssal regions identified previously unknown differences in the composition of byssal threads, plaques, and the adhesive interface, which are believed to correlate to the different roles of these components in the overall structure.
Exploring Environmental Justice and Interrogating 'Community Engagement': A Case Study in the Latin American Community of Toronto
Keywords: Environmental Justice
Environmental Health
Community Engagement
Social Justice
Race
Immigration
Toronto

Equitable opportunity for participation in environmental decision-making is central to arguments for environmental justice, yet remains an under-explored area in the literature. This thesis investigates engagement on environmental health issues in the Latin American community of Toronto. Drawing on an environmental justice framework, the objective of this study was to better understand barriers and facilitators to environmental action in this community, while exploring underlying definitions of environmental health, environmentalism, and community engagement. In-depth interviews were carried out with representatives of agencies serving the Latin American community; qualitative data from focus groups and interviews with community members was also used. Results identify social inequality and the whiteness of the mainstream environmental movement as pervasive barriers to participation, and suggest the utility of linking environmental and social justice concerns for community mobilization. The findings of this research contribute to an emerging discourse on environmental justice and racism in Canada.
Post-stroke Fatigue: Refining the Concept
Keywords: stroke
fatigue
rehabilitation
mental health

Post-stroke fatigue (PSF) is a common yet under-diagnosed and undertreated phenomenon. The unresolved debate over what is PSF has hampered the ability of clinicians to study and develop treatments for this condition. Patients with stroke (n=70) seeking neurorehabilitation at Toronto Rehabilitation Institute completed self-report ratings of fatigue, depressive and anxiety symptoms, and sleepiness. Data were collected from objective measures of stroke topography, sleep disorders, physical fatigability and comorbid medical conditions. A Principal-Components Analysis was performed. Factor 1, the “Distress” factor, was comprised of the all of the self-reported scales i.e. depression, anxiety, fatigue and sleepiness. Factor 2, the “Physical State” factor, was comprised of a diagnosis of Obstructive Sleep Apnea, stroke territory and total medical burden. Factor 3, the “Performance” factor, was comprised by the 6 Minute Walk Test. An orthogonal rotation was the most parsimonious fit to the data, suggesting that the three factors are uncorrelated to each other.
Mg/Ca Ratios in Crustose Coralline Algae as Proxies for Reconstructing Labrador Current Variability
Keywords: Paleoclimate
Coralline Algae
Labrador Current
Sea Surface Temperature
Mg/Ca ratios
Climate Change
Northwestern Atlantic

Climate variability in the North Atlantic has been linked in part to the North Atlantic Oscillation (NAO). The NAO influences marine ecosystems in the northwestern Atlantic and the transport variability of the cold Labrador Current (LC). Understanding historic patterns and predicting future changes in LC transport require long-term and high-resolution climate records that are not available from instrumental data sets. This thesis presents the first century-scale sea surface temperature (SST)reconstructions from the Northwestern Atlantic using Mg/Ca ratios in the long-lived crustose coralline algae Clathromorphum compactum. which is characterized by a high Mg-calcite skeleton exhibiting annual growth increments. Results indicate strong correlations between interannual variations in Mg/Ca ratios and instrumental SST. The 131-year algal Mg/Ca record reveals NAO-type periodicities and evidence of past cold events and warming periods associated with basin-wide ecosystem shifts. Negative correlations between LC volume transport and algal Mg/Ca reflect the cooling influence of the LC on eastern Canadian shelf ecosystems.
Hepatocyte Molecular Cytotoxic Mechanism Study of Fructose and its Metabolites Involved in Nonalcoholic Steatohepatitis and Hyperoxaluria
Keywords: Fructose
Hepatocyte toxicity
Nonalcoholic Steatohepatitis
Hyperoxaluria

High chronic fructose consumption is linked to a nonalcoholic steatohepatitis (NASH) type of hepatotoxicity. Oxalate is the major endpoint of fructose metabolism, which accumulates in the kidney causing renal stone disease. Both diseases are life-threatening if not treated. Our objective was to study the molecular cytotoxicity mechanisms of fructose and some of its metabolites in the liver. Fructose metabolites were incubated with primary rat hepatocytes, but cytotoxicity only occurred if the hepatocytes were exposed to non-toxic amounts of hydrogen peroxide such as those released by activated immune cells. Glyoxal was most likely the endogenous toxin responsible for fructose induced toxicity formed via autoxidation of the fructose metabolite glycolaldehyde catalyzed by superoxide radicals, or oxidation by Fenton’s hydroxyl radicals. As for hyperoxaluria, glyoxylate was more cytotoxic than oxalate presumably because of the formation of condensation product oxalomalate causing mitochondrial toxicity and oxidative stress. Oxalate toxicity likely involved pro-oxidant iron complex formation.
Characterization of the Mobility of FcγRIIa in Primary Human Macrophages
Keywords: Cell biology
Biochemistry

Fcγ receptor-mediated phagocytosis is an active process requiring receptor clustering as a signal initiation event. The mechanisms controlling Fcγ receptor clustering are unknown, as are the parameters governing the receptor lateral mobility in the plasma membrane. This work investigated the lateral mobility of Fcγ receptor IIa in resting primary human macrophages using single-molecule tracking methodology. In the absence of ligands, the receptor was found to exist mostly as a monomeric species. Detailed receptor dynamics revealed the existence of two receptor populations: one that was mobile, the other confined. The actin cytoskeleton was shown to be important for receptor confinement but did not affect receptor diffusion. Such findings are important in understanding the mechanisms for receptor clustering and signal initiation in phagocytosis.