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Graduate Theses & Dissertations
Pages
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- Predictive Digital Mapping of Soils in Kitimat, British Columbia
- Soil is an essential natural resource that supports provisioning services such as agriculture, silviculture, and mining. However, there is limited knowledge on forest soil properties across Canada. Digital soil mapping may be used to fill these data gaps, as it can predict soil properties in areas with limited observations. The focus of this study was to develop predictive maps of select soil physicochemical properties for the Kitimat Valley, British Columbia, and apply these maps to assess the potential impacts of sulphur dioxide emissions from an aluminum smelter, on soil properties in the Valley. Exchangeable [Ex.] magnesium, organic matter, pH, coarse fragment, Ex. potassium, bulk density, Ex. calcium, Ex. acidity, and Ex. sodium were all mapped with acceptable confidence. Time to depletion of base cation pools showed that ~240 km2 of the study area had a depletion time of 50 years or less. However, sources of base cations such as atmospheric deposition and mineral weathering were not considered. Author Keywords: acidification, buffering capacity, Digital soil mapping, predictive mapping, regression kriging, soil properties
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- Utilizing Class-Specific Thresholds Discovered by Outlier Detection
- We investigated if the performance of selected supervised machine-learning techniques could be improved by combining univariate outlier-detection techniques and machine-learning methods. We developed a framework to discover class-specific thresholds in class probability estimates using univariate outlier detection and proposed two novel techniques to utilize these class-specific thresholds. These proposed techniques were applied to various data sets and the results were evaluated. Our experimental results suggest that some of our techniques may improve recall in the base learner. Additional results suggest that one technique may produce higher accuracy and precision than AdaBoost.M1, while another may produce higher recall. Finally, our results suggest that we can achieve higher accuracy, precision, or recall when AdaBoost.M1 fails to produce higher metric values than the base learner. Author Keywords: AdaBoost, Boosting, Classification, Class-Specific Thresholds, Machine Learning, Outliers
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- Civil Aviation and Scheduled Air Services in Colonial Botswana, 1935-1966
- This thesis provides an in-depth and chronological study of the development of civil aviation in the Bechuanaland Protectorate (today’s Botswana), and the role played by the British Government in the development of this form of transport. The thesis argues that Her Majesty’s Government’s neglect and very little interest in its protectorate’s civil aviation represented a form of underdevelopment. The study also reveals the constant contradiction between the neglect of the imperial government and the constant lobbying on the part of colonial administration in the Protectorate for the establishment of an air service. To the colonial administrators, civil aviation represented a symbol of modernity and progress as well as more practical advantages such as mobility. The thesis finally concludes that the Bechuanaland Protectorate’s first airline was established due to growing nationalism both locally and on the continent, at large. The British Government facilitated the establishment of the airline as an attempt to appear benevolent to the protectorate on the eve of independence. Author Keywords:
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- Mutation of the B10 Tyrosine and E11 Leucine in Giardia intestinalis Flavohemoglobin
- The flavohemoglobin in Giardia intestinalis (gFlHb) is the only known protozoan member of a protein class typically associated with detoxifying nitric oxide (by oxidation to nitrate) in bacteria and yeast. Mutants of the B10 tyrosine (Y30F) and E11 leucine (L58A), conserved residues thought to influence ligand binding, were expressed and studied using Resonance Raman (RR) spectroscopy. In the wild type protein, RR conducted using a carbon monoxide probe detects two distinct Fe-CO stretches associated with two different active site configurations. In the open configuration, CO does not interact with any polar side chains, while in the closed configuration, CO strongly interacts with one or more distal residues. Analysis of the Y30F mutant provided direct evidence of this tyrosine’s role in ligand stabilization, as it had only a single Fe-CO stretching mode. This stretching mode was higher in energy than the open conformer of the wild type, indicating a residual hydrogen bonding interaction, likely provided by the E7 glutamine (Q54). In contrast the L58A mutant had no effect on the configurational nature of the enzyme. This was unexpected, as the side chain of L58 sits atop the heme and is thought to regulate the access of distal residues to the heme-bound ligand. The similar spectroscopic properties of wild type and L58A suggest that any such regulation would involve rapid conformational dynamics within the heme pocket. Author Keywords: B10 Tyrosine, Catalytic Globin, E11 Leucine, Flavohemoglobin, gFlHb, Giardia intestinalis
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- Investigation of a Model for Stain Selection and a Robust Estimation for Area of Origin in Bloodstain Pattern Analysis
- Bloodstain pattern analysis is fundamental to crime scene investigations by providing insight into the estimation of the area of origin of a blood source. The selection of bloodstains from an impact pattern is the foundation from which the estimation of the area of origin is derived. The purpose of this research was to develop a theoretical model for stain selection and establish a more robust estimation for the area of origin in the analysis of impact patterns. This model was developed by using quantitative data from marked zones on the impact pattern target surface. The minimum distance between the known blood source location and a single bloodstain line of trajectory was calculated for every bloodstain within each pattern investigated. It has been determined that the zone location of a bloodstain is relevant for improving accuracy, and that stains with all alpha angles can be used to calculate an area of origin estimation. Finally, research within this thesis also validated directional analysis and investigated the number of stains that may be required for a precise area of origin estimation. Keywords: Forensic science, Bloodstain, Impact pattern, Bloodstain pattern analysis, Statistics, Forensic Physics
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- Habitat use and community structure of grassland birds in southern Ontario agro-ecosystems.
- Most grassland bird populations are in decline, so it is becoming increasingly important to understand how they use agricultural field types and form their communities. I performed point counts in cultural meadow, intensive agriculture, and non-intensive agriculture areas in 2011 and 2012. Generalized linear models were used to determine the habitat relationships of six focal species. I found that non-intensive agriculture was used most often and intensive agriculture was often avoided, but there were exceptions which indicate habitat use can be species-specific. I determined in which habitats competition was likely occurring and which species pairs were competing in 2011. In 2012, I experimentally tested these relationships by introducing artificial competitors onto sites. By comparing presence-absence data from 2011 to 2012, I found evidence of habitat-mediated interspecific and conspecific attraction involving Bobolink and Grasshopper Sparrow. This research contributes to the current understanding of grassland bird community ecology and conservation. Author Keywords: agriculture, BACI, community ecology, habitat use, species at risk, species interactions
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- Aeolian Impact Ripples in Sand Beds of Varied Texture
- A wind tunnel study was conducted to investigate aeolian impact ripples in sand beds of varied texture from coarsely skewed to bimodal. Experimental data is lacking for aeolian megaripples, particularly in considering the influence of wind speed on ripple morphometrics. Additionally, the modelling community requires experimental data for model validation and calibration. Eighteen combinations of wind speed and proportion of coarse mode particles by mass were analysed for both morphometrics and optical indices of spatial segregation. Wind tunnel conditions emulated those found at aeolian megaripple field sites, specifically a unimodal wind regime and particle transport mode segregation. Remote sensing style image classification was applied to investigate the spatial segregation of the two differently coloured size populations. Ripple morphometrics show strong dependency on wind speed. Conversely, morphometric indices are inversely correlated to the proportion of the distribution that was comprised of coarse mode particles. Spatial segregation is highly correlated to wind speed in a positive manner and negatively correlated to the proportion of the distribution that was comprised of coarse mode particles. Results reveal that the degree of spatial segregation within an impact ripple bedform can be higher than previously reported in the literature. Author Keywords: Aeolian, Impact Ripples, Megaripple, Self-organization, Wind Tunnel
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- VISUAL INFORMATION-PROCESSING AND THE EVOLUTION OF FLAKE MAKING SKILL
- Flaked stones tools are the oldest and longest persisting human cultural remains. Some of these tools were made by hominins who were not anatomically or cognitively modern. My thesis uses an eye-tracking device, developed by psychology, to study modern day novice and expert tool making. By comparing these two groups I was able to characterize the behaviours that lead to successful flake making, and furthermore make inferences about the cognitive capacities that hominins would have had to have to have been successful themselves. This study suggests limited engagement of short-term memory and problem solving skills, which is consistent with other studies. However, this study seems to refute the hypothesis that improvements in hand-eye coordination alone account for the rise of flaked stone technology. My thesis also shows that eye-tracking is a fruitful way to study flake making and, based on my research, I propose several future directions of study. Author Keywords: Eye-tracking, Human Evolution, Knapping, Oldowan, Skill
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- Developing social skills
- Guidelines regarding social skills interventions for children with ASD suggest incorporating a holistic approach. This includes increasing the family’s understanding of deficits associated with ASD, integrations of natural environments, and parents as active agents while supporting their well-being. The current availability of holistic parent-mediated interventions for children with ASD is limited, with no qualitative understanding of its potential benefits for either the parent or child. The current study examined qualitative parent reports on a parent-mediated social skills intervention for children with ASD (TalkAbilityTM) incorporating a longitudinal approach (i.e., 6-month follow-up). Following Braun and Clarke’s model of thematic analysis, data was coded into four themes: 1) communication difficulties, frustrations and progress, 2) social relationships and concerns, 3) communication strategies, and 4) thoughts and emotions surrounding TalkAbilityTM. Results highlight the importance of considering parent experiences regarding interventions for their child’s social communication skills through a qualitative viewpoint. Author Keywords: autism spectrum disorder, parent-mediated intervention, qualitative review
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- Comparison of Nature Activities
- Research shows spending time in nature can result in many positive effects, including improving mood, connection to nature, and environmental concern. Certain activities may increase these positive effects of nature exposure. Citizen science (non-scientists collecting data to contribute to science) and environmental education (receiving information about the environment) are two potential ways to boost the positive effects of nature exposure. But little research has been done comparing citizen science with environmental education. To address this gap in knowledge, undergraduate participants were randomly assigned to spend five minutes outside daily, for two weeks, either simply observing nature, looking for birds, or looking for and recording bird sightings. Over time, all groups experienced improvements in mood, connection to nature, and environmental concern. However, connection to nature increased the most in people who simply observed nature. Unexpectedly, simply spending time in nature was the most effective intervention. Limitations and future directions are discussed. Author Keywords: Citizen Science, Emotional Well-Being, Environmental Concern, Environmental Education, Nature Exposure, Nature Relatedness
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- Endocannabinoid Treatment for the Behavioural and Histopathological Alterations of Epilepsy
- Epilepsy is associated with a variety of cognitive, emotional, and pain-related symptoms, such as impaired memory and learning, increased risk of anxiety and depression, and increased pain sensitivity. Unfortunately, these symptoms are generally untreated with typical pharmacological interventions, which tend to target seizure activity (i.e., ictogenesis) and not the subsequent histopathological and behavioural alterations resulting from epilepsy (i.e., epileptogenesis). Evidence has demonstrated that targeting the endocannabinoid system can alleviate seizure symptoms as well as cognitive, emotional, and pain-related impairments independent of epilepsy. However, research examining the use of endocannabinoid-based treatment for these behavioural symptoms when they are associated with epilepsy is sparse. In the following thesis, two animal models of epilepsy, several behavioural assessments, and immunohistochemical techniques are utilized to assess the effectiveness of endocannabinoid-based treatment for epilepsy’s interictal symptoms. The findings expand our knowledge and offer encouraging evidence for the usefulness of endocannabinoid-based treatment as an epileptogenesis-targeting pharmacological intervention. Author Keywords: animal models, endocannabinoid system, histopathological alterations, interictal symptoms, temporal lobe epilepsy, treatment
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- Mfsd8 regulates growth and multicellular development in Dictyostelium discoideum
- The neuronal ceroid lipofuscinoses (NCLs), commonly known as Batten disease, are a family of inherited neurodegenerative lysosomal storage disorders. CLN7 disease is a subtype of NCL that is caused by mutations in the MFSD8 gene. MFSD8 encodes a lysosomal transmembrane protein that is predicted to play a role in transporting small substrates across membranes. However, little is known about its role and substrate specificity. Previous work identified an ortholog of human MFSD8 in the social amoeba Dictyostelium discoideum and reported its localization to endocytic compartments. In this study, the effects of mfsd8 loss during Dictyostelium growth and multicellular development were further characterized. Dictyostelium mfsd8- cells displayed increased rates of proliferation and pinocytosis in liquid media. During growth, loss of mfsd8 altered lysosomal enzymatic activities and reduced the intracellular and extracellular levels of autocrine proliferation repressor A. mfsd8- cells grown on a lawn of bacteria formed plaques in a shorter period of time compared to WT cells, providing additional support for the enhanced growth of mfsd8- cells. Upon starvation, the aggregation of mfsd8- cells was delayed, and mfsd8- cells formed more mounds that were smaller in size, which may be attributed to the reduced cell-substrate adhesion and altered lysosomal enzymatic activities observed for mfsd8- cells. Following aggregation, tipped mound formation was delayed, however, loss of mfsd8 did not affect the timing of slug/finger and fruiting body formation. Additionally, slug migration was reduced in mfsd8- cells. These aberrant phenotypes, excluding fruiting body formation, were effectively or partially rescued when Mfsd8-GFP was introduced into mfsd8- cells. Overall, these results show that Mfsd8 plays a role in regulating growth and developmental processes in Dictyostelium via lysosomal-associated functions. Author Keywords: CLN7, Dictyostelium discoideum, Lysosomes, MFSD8, Neuronal Ceroid Lipofuscinoses