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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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- Workplace Bullying in Ontario Healthcare Settings
- This thesis builds on scholarship that highlights how expected gender roles serve to both normalize and obscure forms of violence and hostility in health care workplaces. An analysis of 25 labour arbitrations involving cases of bullying reveals how gender relations is a factor in these grievances and relevant policies in Ontario health care facilities. Reinforced by underlying expectations around women as nurturing and men as aggressive, responses to bullying are found to reflect and reproduce embedded gendered power inequalities in labour. While bullying in the workplace is often treated in policy discussions as an individual and identity-neutral phenomenon, this research provides evidence to the contrary. As a consequence, we must interrogate existing legislation and policies, asking how we can develop approaches that account for, respond to, and mitigate the causes of bullying rooted in unequal power relations, including gendered ones. Author Keywords: gender, health care, labour arbitration, policy, workplace bullying, workplace harassment
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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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- Smile and a Neutral Attitude
- This thesis examines the ways in which body image is discussed in online settings. There are three different communities discussed: body positivity, proED (pro-eating disorder), and body neutrality. Both body positivity and proED content are fairly popular online, and both have found significant support and followers on various social medias. In this thesis, I argue that both of these types of content cause significant harm to those who engage with them, primarily because both communities (though different in their approaches to body image) work to uphold the thin ideal. I then bring up the third type of content: body neutrality. Body neutrality has not been given the same academic attention as body positivity and proED content, likely due to its relative infancy. In this thesis, I propose body neutrality as a much healthier way to frame body image online because of its completely neutral stance on fat, thinness, and general body image. Though any work relating to social media is quickly out of date, I hope that this thesis provides an overview of body neutrality and how, in its current form, it provides a more balanced approach to online body image discussions. Author Keywords: body image, body neutrality, body positivity, eating disorders, social media
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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
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- Phosphoric Acid Chemically Activated Waste Wood
- Activated Carbon (AC) is commonly produced by gasification, but there has been increasing interest in chemical activation due to its lower activation temperatures and higher yields. Phosphoric acid, in particular, succeeds in both these areas. Phosphoric acid activated carbon (PAC) can be environmentally sustainable, and economically favourable, when the phosphoric acid used in the activation is recycled. This thesis describes the digestion and activation of waste wood using phosphoric acid, as well as methods used to recover phosphoric acid, functionalize the produced activated carbon with iron salts and then test their efficacy on the adsorption of target analytes, selenite and selenate. In order to achieve an efficient phosphoric acid based chemical activation, further understanding of the activation process is needed. A two-step phosphoric acid activation process with waste wood feed stock was examined. The filtrate washes of the crude product and the surface composition of the produced PAC were characterized using X-ray Photoelectron Spectroscopy (XPS), Fourier Transform-Infrared spectroscopy (FT-IR), Ion Chromatography (IC), and 31P Nuclear Magnetic Resonance (NMR). XPS of the unwashed PAC contained 13.3 atomic percent phosphorous, as phosphoric acid, while the washed sample contained 1.4 atomic percent phosphorous as PO43-, and P2O74-. Using 31P NMR, phosphoric acid was identified as the primary phosphorous species in the acidic 0.1 M HCl washings, with pyrophosphates also appearing in the second 0.1 M NaOH neutralizing wash, and finally a weak signal from phosphates with an alkyl component also appearing in the DI wash. IC showed high concentrations of phosphoric acid in the 0.1 M HCl wash with progressively lower concentrations in both the NaOH and DI washes. Total phosphoric acid recovery was 96.7 % for waste wood activated with 25 % phosphoric acid, which is higher than previous literature findings for phosphoric acid activation. The surface areas of the PAC were in the 1500-1900 m2g-1 range. Both pre and post activation impregnation of iron salts resulted in iron uptake. Pre-activation resulted in only iron(III) speciation while post-activation impregnation of iron(II)chloride did result in iron(II) forming on the PAC surface. The pre-activated impregnated PAC showed little to no adsorption of selenite and selenate. The post-activation impregnated iron(II)chloride removed up to 12.45 ± 0.025 mg selenium per g Iron-PAC. Competitive ions such as sulfate and nitrate had little effect on selenium adsorption. Phosphate concentration did affect the uptake. At 250 ppm approximately 75 % of adsorption capacity of both the selenate and the selenite solutions was lost, although selenium was still preferentially adsorbed. Peak adsorption occurred between a pH of 4 and 11, with a complete loss of adsorption at a pH of 13. Author Keywords: Activated Carbon, doping, Iron, phosphoric acid, selenium
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- Phantoms of Mars
- My analysis of twentieth century Mars science and fiction outlines how the ongoing dialogic between Mars science and fiction publics influences the American frontier dialectic and how Mars serves as the arena where this debate comes to life. It examines connections between myth, science, and fiction by tracing the evolution of historical and literary representations of the American frontier and understandings of Mars spanning the twentieth century. To illustrate these findings, I investigate the fictional visions of the planet in the works of Edgar Rice Burroughs, Ray Bradbury, and Kim Stanley Robinson. Ultimately, Mars is revealed as a fictional frontier where a better way of living may be achievable by transforming the planet and ourselves. Finally, the planet’s physical site holds a haunting potential value that inspires further research and new narratives, which informs the future use of Mars in American culture. Author Keywords: Bradbury, Burroughs, Frontier, Mars, Myth, Robinson