Graduate Theses & Dissertations

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Time Series Algorithms in Machine Learning - A Graph Approach to Multivariate Forecasting
Forecasting future values of time series has long been a field with many and varied applications, from climate and weather forecasting to stock prediction and economic planning to the control of industrial processes. Many of these problems involve not only a single time series but many simultaneous series which may influence each other. This thesis provides methods based on machine learning of handling such problems. We first consider single time series with both single and multiple features. We review the algorithms and unique challenges involved in applying machine learning to time series. Many machine learning algorithms when used for regression are designed to produce a single output value for each timestamp of interest with no measure of confidence; however, evaluating the uncertainty of the predictions is an important component for practical forecasting. We therefore discuss methods of constructing uncertainty estimates in the form of prediction intervals for each prediction. Stability over long time horizons is also a concern for these algorithms as recursion is a common method used to generate predictions over long time intervals. To address this, we present methods of maintaining stability in the forecast even over large time horizons. These methods are applied to an electricity forecasting problem where we demonstrate the effectiveness for support vector machines, neural networks and gradient boosted trees. We next consider spatiotemporal problems, which consist of multiple interlinked time series, each of which may contain multiple features. We represent these problems using graphs, allowing us to learn relationships using graph neural networks. Existing methods of doing this generally make use of separate time and spatial (graph) layers, or simply replace operations in temporal layers with graph operations. We show that these approaches have difficulty learning relationships that contain time lags of several time steps. To address this, we propose a new layer inspired by the long-short term memory (LSTM) recurrent neural network which adds a distinct memory state dedicated to learning graph relationships while keeping the original memory state. This allows the model to consider temporally distant events at other nodes without affecting its ability to model long-term relationships at a single node. We show that this model is capable of learning the long-term patterns that existing models struggle with. We then apply this model to a number of real-world bike-share and traffic datasets where we observe improved performance when compared to other models with similar numbers of parameters. Author Keywords: forecasting, graph neural network, LSTM, machine learning, neural network, time series
Population Genetics and Gut Microbiome Composition Reveal Subdivisions and Space Use in a Generalist and Specialist Ungulate
Natural populations are often difficult and costly to study, due to the plethora of confounding processes and variables present. This is of particular importance when dealing with managed species. Ungulates, for example, act as both consumers and prey sources; they also provide economic benefit through harvest, and as such, are of high ecological and economic value. I addressed conservation and management concerns by quantifying subdivision in wild populations and combined movement with non-invasive sampling to provide novel insight on the physiological drivers of space use in multiple species. This thesis explored biological patterns in ungulates using two distinct approaches: the first used molecular genetics to quantify gene flow, while the second examined the relationship between movement and the gut microbiome using high-throughput sequencing and GPS tracking. The goal of the first chapter was to quantify gene flow and assess the population structure of mountain goats (Oreamnos americanus) in northern British Columbia (BC) to inform management. I used microsatellites to generate genotype data and used a landscape genetics framework to evaluate the possible drivers behind genetic differentiation. The same analyses were performed at both a broad and fine scale, assessing genetic differentiation between populations in all of northern BC and in a case management study area northeast of Smithers BC. The results indicated panmixia among mountain goats regardless of scale, suggesting distance and landscape resistance were minimally inhibiting gene flow. Therefore, management at local scales can continue with little need for genetically informed boundaries, but regulations should be tailored to specific regions incorporating data on local access and harvest pressure. My second chapter aimed to determine the extent to which the gut microbiome drives space-use patterns in a specialist (mountain goat) and generalist (white-tailed deer, Odocoileus virginianus) ungulate. Using fecal samples, we generated genomic data using 16S rRNA high-throughput sequencing to evaluate gut diversity and gut microbiome characteristics. Additionally, individuals were fitted with GPS collars so that we could gain insight into movement patterns. Gut microbiome metrics were stronger predictors of space use and movement patterns with respect to home range size, whereas they were weaker predictors of habitat use. Notably, factors of both the gut microbiome and age of a given species were correlated with changes in space use and habitat use. Ultimately, this research linked high-throughput sequencing and GPS data to better understand ecological processes in wild ungulates. Author Keywords: gene flow, genomics, gut microbiome, home range, population genetic structure, ungulates
Automated Separation and Preconcentration of Ultra-Trace Levels of Radionuclides in Complex Matrices by Online Ion Exchange Chromatography Coupled with Inductively Coupled Plasma Mass Spectrometry (ICP-MS)
Radionuclides occur in the environment both naturally and artificially. Along with weapons testing and nuclear reactor operations, activities such as mining, fuel fabrication and fuel reprocessing are also major contributors to nuclear waste in the environment. In terms of nuclear safety, the concentration of radionuclides in nuclear waste must be monitored and reported before storage and/or discharge. Similarly, radionuclide waste from mining activities also contains radionuclides that need to be monitored. In addition, a knowledge of ongoing radionuclide concentrations is often required under certain ‘special’ conditions, for example in the area surrounding nuclear and mining operations, or when nuclear and other accidents occur. Thus, there is a huge demand for new methods that are suitable for continuously monitoring and rapidly analyzing radionuclide levels, especially in emergency situations. In this study, new automated analytical methods were successfully developed to measure ultra trace levels of single or multiple radionuclides in various environmental samples with the goal of faster analysis times and less analyst involvement while achieving detection limits suitable for typical environmental concentrations. Author Keywords: automation, ICP-MS, ion exchange, radionuclide
WOMEN IN HORROR
The objective of this dissertation is to measure the influence of the contemporary influx of women’s involvement in the horror genre in three dimensional capacities: female representation in horror films, female representation as active, participatory spectators and female representation in the industrial production of horror. Through the combined approach of theoretical and empirical analysis, this dissertation examines the social conditions that facilitated women’s infiltration of the horror genre. Beginning with psychoanalytic theories of spectatorship, it is demonstrated that female filmmakers have challenged horror’s traditional images of victimized women through the development new forms of feminine representation in contemporary horror films. Using data collected from a sample of 52 self-identified female horror fans, it is revealed that the purported invisibility of female horror spectators is a consequence of their alternative modes of consumption. Through interviews conducted with four female producers and an examination of their cultural productions, I illustrate that women have reconstituted the horror genre as a space for inclusivity, political activism and feminist empowerment. Cohesively, these findings reveal the contemporary feminist reclamation of horror to be a form of resistance intended to challenge the patriarchal structures that facilitated women’s historical exclusion from the horror genre. Author Keywords: Abjection, Feminism, Film, Gender, Horror, Psychoanalysis
History and Legacy of the “Orillia Asylum for Idiots
The “Orillia Asylum for Idiots” (1861 - 2009), Canada’s oldest and largest facility for the care and protection of children and adults with disabilities, was once praised as a beacon of humanitarian progress and described as a “community within a community.” Yet, survivors who lived in the facility during the post Second World War period, a time described as the “golden age of children’s rights,” tell harrowing stories of abuse and neglect. Despite the nation’s promise to “put children first” and protect the universal rights of “Canada’s children,” children incarcerated within the Orillia Asylum were subjected to systemic neglect and cultural discrimination, daily humiliation and dehumanization, and physical, sexual, and emotional abuse. Far from being a place for child protection and care, this dissertation finds that the Orillia Asylum was a site of a multi-faceted and all-encompassing violence, a reality that stands in complete contrast to the grand narrative through which the facility has historically been understood. This dissertation considers how such violence against children could occur for so long in a facility maintained by the state, a state invested in protecting children. It finds that children who were admitted to the Orillia Asylum were not considered to be “Canada’s children” at all by virtue of being labelled as “mentally deficient,” “feeble-minded,” “not-quite-human,” and “not-quite-children.” Author Keywords: childhood, disability, Huronia Regional Centre, institutional child abuse, institutional violence, institutionalization
Enhanced weathering and carbonation of kimberlite residues from South African diamond mines
Mafic and ultramafic mine wastes have the potential to sequester atmospheric carbon dioxide (CO2) through enhanced weathering and CO2 mineralization. In this study, kimberlite residues from South African diamond mines were investigated to understand how weathering of these wastes leads to the formation of secondary carbonate minerals, a stable sink for CO2. Residues from Venetia Diamond Mine were fine-grained with high surface areas, and contained major abundances of lizardite, diopside, and clinochlore providing a maximum CO2 sequestration capacity of 3–6% of the mines emissions. Experiments utilized flux chambers to measure CO2 drawdown within residues and unweathered kimberlite exhibited greater negative fluxes (-790 g CO2/m2/year) compared to residues previously exposed to process waters (-190 g CO2/m2/year). Long-term weathering of kimberlite residues was explored using automated wet-dry cycles (4/day) over one year. Increases in the δ13C and δ18O values of carbonate minerals and unchanged amount of inorganic carbon indicate CO2 cycling as opposed to a net increase in carbon. Kimberlite collected at Voorspoed Diamond Mine contained twice as much carbonate in yellow ground (weathered) compared to blue ground, demonstrating the ability of kimberlite to store CO2 through prolonged weathering. This research is contributing towards the utilization of kimberlite residues and waste rock for CO2 sequestration. Author Keywords: CO2 fluxes, CO2 mineralization, CO2 sequestration, Enhanced weathering, Kimberlite, Passive carbonation
Fungal pathogen emergence
The emergence of fungal hybrid pathogens threatens sustainable crop production worldwide. To investigate hybridization, the related smut fungi, Ustilago maydis and Sporisorium reilianum, were selected because they infect a common host (Zea mays), can hybridize, and tools are available for their analysis. Hybrid dikaryons exhibited filamentous growth on plates but reduced virulence and limited colonization in Z. mays. Select virulence genes in the hybrid had similar transcript levels on plates and altered levels during infection of Z. mays relative to each parental dikaryon. Virulence genes were constitutively expressed in the hybrid to determine if its pathogenic development could be influenced. Little impact was observed in hybrids with increased expression of effectors known to modify host response and metabolism. However, increased expression of transcriptional regulators of stage specific pathogenic development increased the hybrid’s capacity to induce symptoms. These results establish a base for investigating molecular aspects of fungal hybrid pathogen emergence. Author Keywords: effectors, hybrid pathogenesis assays, Sporisorium reilianum, transcription factors, Ustilago maydis, virulence factors
Extraction and Characterization of Hyaluronic Acid and Collagen from Eggshell Membrane Waste
Connecting academia to industry is one important way to advance towards meeting the United Nations (UN) Sustainability Goals (SDGs).1 Sustainability can be applied to all industrial sectors with the SDGs being implemented by 2030.2 This research contributes to the SDGs by investigating a way to remediate an industrial waste stream in the egg-breaking industry. If adopted, this would reduce the amount of eggshell membrane (ESM) waste placed in landfill where it does not decompose properly. The work described in this thesis specifically targets extraction of collagen and hyaluronic acid (HA), two components of the ESM that are of commercial value in the cosmetic, pharmaceutical, and biomedical industries3,4 . Deliverables from this research include economically viable extraction methods, developed based on green chemistry approaches, that can be transferred from lab bench to industrial scale. The extraction development process was guided by the 12 Principles of Green Chemistry5,6,7 and the 12 Principles of Green Engineering.8 HA was most successfully extracted using a sodium acetate solution on ground ESM. Filtrate was collected, exhaustively dialyzed and lyophilized. High molecular weight HA was recovered. Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy and proton nuclear magnetic resonance (NMR) spectroscopy compared extracted material to reference HA identifying successful extraction. Collagen was extracted using acetic acid or pepsin enzyme digestion. Hydrophilic interaction liquid chromatography (HILIC) coupled with mass spectrometry (MS) compared amino acid composition of extracted materials to reference collagen material. FTIR-ATR spectra also supported successful extraction of collagen. This work identifies that HA and collagen can be conveniently extracted from ESM using an economical approach that can be implemented into egg-breaking facilities. This work highlights the benefits of connecting academia to industry to advance green chemical approaches while implementing sustainable practices into existing industry. Author Keywords: collagen, eggshell membrane waste, extraction, green chemistry, hyaluronic acid, sustainability
Adoption of a Finite Element Model of Material Deformation Relevant to Studying Corneal Biomechanics
The human cornea is required to exhibit specific material properties to maintain its regular shape under typical intraocular pressures which then allow for its correct optical functionality. In this thesis, the basis of continuum solid mechanics and the finite element method are introduced. We use finite element modelling to simulate the extension of an effective-1d, linear-elastic bar, a cornea-like body governed by Poisson’s equation, and the deformation of a loaded, linear-elastic, cube. Preliminary results for the deformation of a simulated, linear-elastic, cornea have also been achieved using the finite element approach. Author Keywords: continuum solid mechanics, corneal biomechanics, finite element method, intraocular pressure
Modelling Depressive Symptoms in Emerging Adulthood
Depression during the transition into adulthood is a growing mental health concern, with overwhelming evidence linking the developmental risk for depressive symptoms with maternal depression. In addition, there is a lack of research on the protective role of socioemotional competencies in this context. This study examines independent and joint effects of maternal depression and trait emotional intelligence (TEI) on the longitudinal trajectory of depressive symptoms during emerging adulthood. A series of latent growth models was applied to three biennial cycles of data from a nationally representative sample (N=933) from the Canadian National Longitudinal Survey of Children and Youth. We assessed the trajectory of self-reported depressive symptoms from age 20 to 24 years, as well as whether it was moderated by maternal depression at age 10 to 11 and TEI at age 20, separately by gender. The results indicated that mean levels of depression declined during the emerging adulthood in females, but remained relatively stable in males. Maternal depressive symptoms significantly positively predicted depressive symptoms across the entire emerging adulthood in females, but only at age 20-21 for males. In addition, likelihood of developing depressive symptoms was attenuated by higher global TEI in both females and males, and additionally by higher interpersonal skills in males. Our findings suggest that interventions for depressive symptoms in emerging adulthood should consider development of socioemotional competencies. Author Keywords: Depression, Depressive Symptoms, Emerging Adulthood, Intergenerational Risk, Longitudinal, Trait Emotional Intelligence
UV-Curable hybrid sol-gel materials
This thesis describes the synthesis, application and evaluation of a UV crosslinked 3-methacryloxypropyltrimethoxysilane-derived coating formulation. This is a two-component sol-gel system with 3-methacryloxypropyltrimethoxysilane (MaPTMS) and tetraethoxysilane (TEOS). Herein we show that if we change the co-solvent required for solubilizing MaPTMS from the more common methanol and ethanol to isopropanol we change the rate of hydrolysis from days or weeks to minutes. With the assistance of 2D 29Si-NMR we demonstrate that the system undergoes extensive condensation in twenty minutes. Using standard UV irradiation, the material can be extensively UV crosslinked with 70% of the methacryloxy functionality being consumed in 5 minutes upon irradiation in the presence of a photo-initiator. When this material is used to coat low carbon steel and immersed in an accelerated corrosion solution (dilute Harrison’s solution); this material affords low carbon steel 25 hours of protection when crosslinked and 17 hours of protection when uncrosslinked. The material was then used to encapsulate polyaniline (PANI), an intrinsic conductive polymer used in the corrosion protection of metal substrates. PANI has been encapsulated previously in sol-gel material, but due to the pH dependence of the solubility of PANI, it can not be encapsulated in more commonly chemically crosslinked sol-gel. As our system is UV crosslinked rather than chemically crosslinked, we were able to successfully demonstrate the inclusion of PANI into our coating system. Finally, this thesis includes a thorough computational investigation into the structure and band gap of PANI. Through the analysis of the band gap it was shown that the structure of the polymer commonly displayed in literature is not the correct structure of the polymer. Our results suggest that when PANI is made electrochemically, the oligomer contains two quinoid units next to one another instead of the more usually represented regularly alternating benzoid and quinoid units. The results also suggest that when PANI is made using the oxidant ammonium persulfate, the polymer most likely contains a Michael adduct structure somewhere in the polymer chain which dominates PANI’s electronic properties. Author Keywords: 3-Methacryloxypropyltrimethoxysilane, Computational Chemistry , Corrosion , Polyaniline, Tetraethoxysilane
Surface temperature regulation during stress exposure
The influence of stress exposure on the body temperature of vertebrates has been known for nearly two-thousand years. While the proximate mechanisms supporting this phenomenon are well described, the ultimate mechanisms remain enigmatic. In this thesis, I propose a novel hypothesis which states that changes in body surface temperature (henceforth "surface temperature") following stress exposure occur to reduce energetic expenditure toward thermoregulation, thus freeing energy for use in the stress response (hereafter, the "Thermoprotective Hypothesis"). Using a paired experimental design, I first show that black-capped chickadees (Poecile atricapillus, Linnaeus, 1766) exposed to repeated stressors decrease their surface temperatures at low ambient temperatures, and increase their surface temperatures at high ambient temperatures relative to unstressed controls. These changes in surface temperature contribute to a relative reduction in heat loss in the cold, and a relative increase in heat dissipation in the warmth among stress-exposed individuals, thus reducing their energetic demands toward more costly thermoregulatory strategies. Next, I show that stress-induced changes in surface temperature are most pronounced in chickadees that experience naturally-occurring resource-restrictions, suggesting that this response occurs to balance allocation of energy among the stress response and thermoregulation (i.e. a true energetic trade-off ). Third, I show that the magnitudes of chronic, stress-induced changes in surface temperature are highly variable among, and highly consistent within, chickadees, therefore suggesting that this response could hold adaptive significance if such variation among individuals is heritable. Finally, using domestic pigeons (Columba livia domestica, Gmelin, 1789) as a model species, I show that stress-induced changes in surface temperature are highly pronounced at bare tissues with a critical role in thermoregulation for some avian species (the bill), when compared with responses at surrounding bare tissues (the eye region). Together, these findings strongly support the Thermoprotective Hypothesis and suggest that endotherms may trade energetic investment toward thermoregulation with that toward the stress response in resource-limiting environments. Author Keywords: heat transfer, infrared thermography, stress physiology, surface temperature, thermoregulation, trade-off

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Format: 2021/10/25