Graduate Theses & Dissertations

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Exploring Kiki-Inoomgugaewin
This case study contributes to scholarship surrounding the national conversation on Indigenous language sustainability in North America. Much of this scholarship provides insight on structuring language programs and policies for youth, leaving a tremendous research gap regarding sociolinguistic and cultural research with youth. Youth appear disinterested or otherwise set apart in current research from the development of policies and curriculum concerned with heritage languages. Upon closer inspection; however, youth are engaged and using innovative and different tools than previous generations. This exploration is a foundational case study which builds upon research highlighting the nature of Indigenous language loss in the south as a time sensitive phenomenon as the application of cognitive imperialism and colonial tactics within mainstream schools continue to conceal a large scale cultural and linguistic genocide in Canada. Although Indigenous language loss may seem of concern to only small groups of linguists and dialectic communities, it should in fact concern anyone who cares about reconciliation or closing the tremendous gap in accessing equitable education. The preservation of Indigenous languages and knowledge systems should also be of interest to those parties who seek to comprehensively understand the Natural World and whom have a vested interest in the survival of the planet and protection of the enviroment. Because of these realities, the viewpoints and experiences of all concerned parties are essential. It follows then, that the youth perspective is significant. To address this gap, participatory narrative inquiry was used as a theoretical framework to conduct a foundational case study in which detailed consideration was given to exploring the lived narratives of three Anishnaabeg participants to establish the value of Indigenous youth voice in alternative forms of sociolinguistic and culturally sustainable language learning in the 21st century, and, to strengthen the argument that more research is needed in the field of first-person youth studies. The results of this case study will be useful, specifically, to localized communities of Anishnaabe youth with and for whom much of the research was conducted, and, more generally to youth resistance work focused on media and technology in globalized and contemporary language and cultural ecologies. Research outcomes indicated potential directions for future research in different contexts and localities by presenting commonalities within the fields of social and political engagement and their connection to language and new media in youth populations. It is hoped that this initial material pinpointing a research gap in Indigenous youth language studies will be used to investigate future research in this field. Author Keywords: Anishnaabe, Decolonization, Language, Sociolinguistics, Technology, Youth Studies
Emerging Dynamic Social Learning Theory of a Learning Community of Practice
In current knowledge-based economy, knowledge might be viewed as the most valuable organizational resource in sustaining any organization. Organizational knowledge originates from cognitive learning by individuals situated within organizations. In organizational learning, situated learning of knowledge by individuals is shared to create sustainable organizational competency. Yet, there is inadequate research to understand how situated learning operates as a social learning system within Community of Practice (‘CoP’). Through a case study of a multi-level, non-profit CoP in Ontario, Canada, this qualitative explanatory research contributes to the extant literature by building a unique theoretical framework that provides conceptual insights on linkages between organizational knowledge, social learning system, and organizational competency, in sustaining the organizational CoP. Using Straussian grounded theory methodology, qualitative primary data from in-depth interviews, participant observations, and documents were triangulated and analysed abductively to reveal an emerging dynamic knowledge-based social learning theory towards explaining how situated learning sustains this learning CoP. Author Keywords: Community of Practice, Grounded Theory, Organizational Knowledge, Organizational Learning, Organizational Sustainability, Situated Learning
Characterization of a Zn(II)2Cys6 transcription factor in Ustilago maydis and its role in pathogenesis
Ustilago maydis (D.C.) Corda is a biotrophic pathogen that secretes effectors to establish and maintain a relationship with its host, Zea mays. In this pathosystem, the molecular function of effectors is well-studied, but the regulation of effector gene expression remains largely unknown. This study characterized Zfp1, a putative U. maydis Zn(II)2Cys6 transcription factor, as a modulator of effector gene expression. The amino acid sequence of Zfp1 indicated the presence of a GAL4-like zinc binuclear cluster as well as a fungal specific transcription factor domain. Nuclear localization was confirmed by tagging Zfp1 with enhanced green fluorescent protein. Deletion of zfp1 resulted in attenuated hyphal growth, reduced infection frequency, an arrest in pathogenic development, and decreased anthocyanin production. This phenotype can be attributed to the altered transcript levels of genes encoding predicted and confirmed U. maydis effectors in the zfp1 deletion strain during pathogenic growth. Complementation of zfp1 deletion strain with tin2, an effector involved in anthocyanin induction, suggested this effector is downstream of Zfp1 and its expression is influenced by this transcription factor during in planta growth. When wild-type zfp1 was ectopically inserted in the zfp1 deletion strain, pathogenesis and virulence were partially restored. This, coupled with zfp1 over-expression strains having a similar phenotype as the deletion strains, suggested Zfp1 may interact with other proteins for full function. These findings show that Zfp1, in conjunction with one or more binding partners, contributes to U. maydis pathogenesis, virulence, and anthocyanin production through the regulation of effector gene expression. Author Keywords: effector, pathogenesis, transcription factor, Ustilago maydis, Zea mays, zinc finger
Balance is key
While preferences for symmetry are seemingly universal, they can be seen at their most extreme among individuals high in trait incompleteness. As yet, it is unclear why incompleteness yields heightened symmetry preferences. Summerfeldt et al. (2015) speculated that individuals high in incompleteness may develop heightened preferences for symmetry due to its greater perceptual fluency. Accordingly, the aim of the present set of three experiments was to examine this relationship. Implicit preferences for symmetry were measured using a modified version of the Implicit Association Test (IAT) reported by Makin et al. (2012). Experiments 1 (N = 24) and 2 (N = 24) examined whether the general implicit preferences for symmetry and influence of perceptual fluency reported by Makin et al. (2012) extended to a within-subjects design. Experiment 3 (N = 86) examined whether trait incompleteness is related to greater implicit preferences for symmetric stimuli, and whether perceptual fluency affects this association. Results showed that incompleteness and implicit preferences were related, and that incompleteness-related differences in preferences were eliminated when the patterns were equally perceptually fluent, supporting the idea that incompleteness-related preferences for symmetry are linked to perceptual fluency. Implications of these findings are discussed. Author Keywords:
Relationship Between Precarious Employment, Behaviour Addictions and Substance Use Among Canadian Young Adults
This thesis utilized a unique data-set, the Quinte Longitudinal Survey, to explore relationships among precarious employment and a range of mental health problems in a representative sample of Ontario young adults. Study 1 focused on various behavioural addictions (such as problem gambling, video gaming, internet use, exercise, compulsive shopping, and sex) and precarious employment. The results showed that precariously employed men were preoccupied with gambling and sex while their female counterparts preferred shopping. Gambling and excessive shopping diminished over time while excessive sexual practices increased. Study 2 focused on the association between precarious employment and substance abuse (such as tobacco, alcohol, cannabis, hallucinogens, stimulants, and other substances). The results showed that men used cannabis more than women, and the non-precarious employed group abused alcohol more than individuals in the precarious group. This research has implications for both health care professionals and intervention program developers when working with young adults in precarious jobs. Author Keywords: Behaviour Addictions, Precarious Employment, Substance Abuse, Young Adults
Exploring the Scalability of Deep Learning on GPU Clusters
In recent years, we have observed an unprecedented rise in popularity of AI-powered systems. They have become ubiquitous in modern life, being used by countless people every day. Many of these AI systems are powered, entirely or partially, by deep learning models. From language translation to image recognition, deep learning models are being used to build systems with unprecedented accuracy. The primary downside, is the significant time required to train the models. Fortunately, the time needed for training the models is reduced through the use of GPUs rather than CPUs. However, with model complexity ever increasing, training times even with GPUs are on the rise. One possible solution to ever-increasing training times is to use parallelization to enable the distributed training of models on GPU clusters. This thesis investigates how to utilise clusters of GPU-accelerated nodes to achieve the best scalability possible, thus minimising model training times. Author Keywords: Compute Canada, Deep Learning, Distributed Computing, Horovod, Parallel Computing, TensorFlow
Alien Imaginaries
This dissertation offers a cultural analysis of UFOs and extraterrestrials in the United States. In it I look at what I call real aliens — extraterrestrials believed to be real and interacting with humans on Earth. Beliefs in real aliens are often denigrated and dismissed in official discourse, yet they continue to not only persist, but thrive, in American society. Hence, this dissertation asks: Why do so many people believe that extraterrestrials are visiting our planet? Part One begins by tracing the invasion of real aliens in the United States using Orson Welles’s 1938 radio broadcast “The War of the Worlds” as a starting point. Here, I look at how and why the broadcast registered with listeners’ anxieties and created a fantastic and uncanny effect that made it possible for some to conceive of aliens invading the United States. In Part Two, I trace the rise of ufology, which involves the study of extraterrestrials currently interacting with humans on Earth, and I consider how the social and political climate of the Cold War, as well as the cultural environment of postmodernity, provided the necessary conditions for stories about aliens to be made believable. Part Three explores the case study of the Roswell Incident, a conspiracy theory about the origins of an alleged flying saucer crash and government cover-up. I look at the reasons for why many individuals have come to believe in this conspiracy theory and I reflect on the tensions between “official” and “unofficial” discourses surrounding this case. I also consider how and why Roswell has become such an important site for ufology, and I examine the performances given by ufologists at the annual Roswell International UFO Festival to appreciate how ufologists offers seductive explanations of why things are the way they are; for many, their stories offer a better version of events than the purely rational and positivist explanations offered by official sources, especially since they tap into the disillusionment and mistrust that many Americans feel about contemporary politics. Author Keywords: aliens/extraterrestrials, America, conspiracy, official and unofficial, storytelling, ufology
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
Population-Level Ambient Pollution Exposure Proxies
The Air Health Trend Indicator (AHTI) is a joint Health Canada / Environment and Climate Change Canada initiative that seeks to model the Canadian national population health risk due to acute exposure to ambient air pollution. The common model in the field uses averages of local ambient air pollution monitors to produce a population-level exposure proxy variable. This method is applied to ozone, nitrogen dioxide, particulate matter, and other similar air pollutants. We examine the representative nature of these proxy averages on a large-scale Canadian data set, representing hundreds of monitors and dozens of city-level populations. The careful determination of temporal and spatial correlations between the disparate monitors allows for more precise estimation of population-level exposure, taking inspiration from the land-use regression models commonly used in geography. We conclude this work with an examination of the risk estimation differences between the original, simplistic population exposure metric and our new, revised metric. Author Keywords: Air Pollution, Population Health Risk, Spatial Process, Spatio-Temporal, Temporal Process, Time Series
Near-road assessment of traffic related air pollutants along a major highway in Southern Ontario
The spatial and temporal variation in atmospheric nitrogen dioxide (NO2), ammonia (NH3), and 17 elements (V, Cr, Fe, Ni, Cu, Zn, As, Cd, Pb, Mg, Al, Ca, Co, Se, Sb, Mn, and Na) were measured at 40 road side locations along a ~250 km traffic density gradient of 40,000–400,000 vehicles on the King’s Highway 401, in Ontario, Canada. Elemental concentrations were measured over a year, using moss bags as passive samplers, for four quarterly three-month exposure periods (October 2015 – October 2016). Gaseous NO2 and NH3 concentrations were measured using Willem’s badge passive diffusive samplers for twelve one-week exposure periods (one per month: October 2015–October 2016). Dry deposition of nitrogen was estimated using the inferential method. There were significant linear relationships between NO2 and NH3 and average annual daily traffic (AADT) volumes across the study area; higher concentrations corresponded to higher volume traffic sites. Average NO2 concentrations at sites ranged from 23.5 to 73 μg/m3, with an annual average of 43.7 μg/m3. Ammonia ranged from 2.56 to 13.55 μg/m3, with an annual average of 6.44 μg/m3. There were significant quarterly variations in NO2, with concentrations peaking during the winter months. In contrast, NH3 showed no significant quarterly variation, but a slight peak occurred during the summer. Gaseous NO2 and NH3 were highly positively correlated (r = 0.63), suggesting a common emission source from traffic. Concentrations in exposed moss were determined by subtracting the total concentration of each metal in the exposed sample from the background concentration present in the moss. Relative accumulation factors (RAF) and contamination factors were also calculated to determine the anthropogenic influence on tissue concentrations in exposed moss. All metals showed elevated levels versus background concentrations, with all metals except Ni and Co showing considerable enrichment. The highest levels of contamination were from V, Cr, Fe, Zn, Cd, Sb, Pb and Na. Principal component analysis indicated 5 clear clusters of related elements, with PC1 accounting for 36.2% and PC2 accounting for 25.6% of the variance. Average annual daily traffic was significantly related to Cr, Fe, Cu, Sb, Mn, Al, and Na. Road side monitoring shows consistently higher concentrations than active monitoring sites located further from the edge of the road, indicating a need for increased road side monitoring in Ontario, Canada. Author Keywords:
Role of Dielectric Screening in SrTiO3-Based Interfaces
We build a theoretical model for exploring the electronic properties of the two-dimensional (2D) electron gas that forms at the interface between insulating SrTiO3 (STO) and a number of perovskite materials including LaTiO3, LaAlO3, and GdTiO3. The model treats conduction electrons within a tight-binding approximation, and the dielectric polarization via a Landau-Devonshire free energy that incorporates STO's strongly nonlinear, nonlocal, field-, and temperature-dependent dielectric response. We consider three models for the dielectric polarization at the interface: an ideal-interface model in which the interface has the same permittivity as the bulk, a dielectric dead-layer model in which the interface has permittivity lower that the bulk, and an interfacial-strain model in which the strain effects are included. The ideal-interface model band structure comprises a mix of quantum 2D states that are tightly bound to the interface, and quasi-three-dimensional (3D) states that extend hundreds of unit cells into the STO substrate. We find that there is a substantial shift of electrons away from the interface into the 3D tails as temperature is lowered from 300 K to 10 K. We speculate that the quasi-3D tails form the low- density high-mobility component of the interfacial electron gas that is widely inferred from magnetoresistance measurements. Multiple experiments have observed a sharp Lifshitz transition in the band structure of STO interfaces as a function of applied gate voltage. To understand this transition, we first propose a dielectric dead-layer model. It successfully predicts the Lifshitz transition at a critical charge density close to the measured one, but does not give a complete description for the transition. Second, we use an interfacial-strain model in which we consider the electrostrictive and flexoelectric coupling between the strain and polarization. This coupling generates a thin polarized layer whose direction reverses at a critical density. The transition occurs concomitantly with the polarization reversal. In addition, we find that the model captures the two main features of the transition: the transition from one occupied band to multiple occupied bands, and the abrupt change in the slope of lowest energy band with doping. Author Keywords:
Hybridization dynamics in cattails (Typha spp.,) in northeastern North America
Interspecific hybridization is an important evolutionary process which can contribute to the invasiveness of species complexes. In this dissertation I used the hybridizing species complex of cattails (Typha spp., Typhaceae) to explore some of the processes that could contribute to hybridization rates. Cattails in northeastern North America comprise the native T. latifolia, the non-native T. angustifolia, and their fertile hybrid, T. × glauca. First, I examined whether these taxa segregate by water depth as habitat segregation may be associated with lower incidence of hybridization. I found that these taxa occupy similar water depths and therefore that habitat segregation by water depth does not promote mating isolation among these taxa. I then compared pollen dispersal patterns between progenitor species as pollen dispersal can also influence rates of hybrid formation. Each progenitor exhibits localized pollen dispersal, and the maternal parent of first generation hybrids captures more conspecific than heterospecific pollen; both of which should lead to reduced hybrid formation. I then conducted controlled crosses using all three Typha taxa to quantify hybrid fertility and to parameterize a fertility model to predict how mating compatibilities should affect the composition of cattail stands. I found that highly asymmetric formation of hybrids and backcrosses and reduced hybrid fertility should favour the maintenance of T. latifolia under certain conditions. Finally, I used a population genetics approach to characterize genetic diversity and structure of Typha in northeastern North America to determine the extent to which broad-scale processes such as gene flow influence site-level processes. I concluded that hybrids are most often created within sites or introduced in small numbers rather than exhibiting broad-scale dispersal. This suggests that local processes are more important drivers of hybrid success than landscape-scale processes which would be expected to limit the spread of the hybrid. Though my findings indicate some barriers to hybridization in these Typha taxa, hybrid cattail dominates much of northeastern North America. My results therefore show that incomplete barriers to hybridization may not be sufficient to prevent the continued dominance of hybrids and that active management of invasive hybrids may be required to limit their spread. Author Keywords: fertility model, genetic structure, Hybridization, invasive species, niche segregation, pollen dispersal

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