Graduate Theses & Dissertations

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"Multimodal Contrast" from the Multivariate Analysis of Hyperspectral CARS Images
The typical contrast mechanism employed in multimodal CARS microscopy involves the use of other nonlinear imaging modalities such as two-photon excitation fluorescence (TPEF) microscopy and second harmonic generation (SHG) microscopy to produce a molecule-specific pseudocolor image. In this work, I explore the use of unsupervised multivariate statistical analysis tools such as Principal Component Analysis (PCA) and Vertex Component Analysis (VCA) to provide better contrast using the hyperspectral CARS data alone. Using simulated CARS images, I investigate the effects of the quadratic dependence of CARS signal on concentration on the pixel clustering and classification and I find that a normalization step is necessary to improve pixel color assignment. Using an atherosclerotic rabbit aorta test image, I show that the VCA algorithm provides pseudocolor contrast that is comparable to multimodal imaging, thus showing that much of the information gleaned from a multimodal approach can be sufficiently extracted from the CARS hyperspectral stack itself. Author Keywords: Coherent Anti-Stokes Raman Scattering Microscopy, Hyperspectral Imaging, Multimodal Imaging, Multivariate Analysis, Principal Component Analysis, Vertex Component Analysis
ADAPT
This thesis focuses on the design of a modelling framework consisting of loose-coupling of a sequence of spatial and process models and procedures necessary to predict future flood events for the years 2030 and 2050 in Tabasco Mexico. Temperature and precipitation data from the Hadley Centers Coupled Model (HadCM3), for those future years were downscaled using the Statistical Downscaling Model (SDSM4.2.9). These data were then used along with a variety of digital spatial data and models (current land use, soil characteristics, surface elevation and rivers) to parameterize the Soil Water Assessment Tool (SWAT) model and predict flows. Flow data were then input into the Hydrological Engineering Centers-River Analysis System (HEC-RAS) model. This model mapped the areas that are expected to be flooded based on the predicted flow values. Results from this modelling sequence generate images of flood extents, which are then ported to an online tool (ADAPT) for display. The results of this thesis indicate that with current prediction of climate change the city of Villahermosa, Tabasco, Mexico, and the surrounding area will experience a substantial amount of flooding. Therefore there is a need for adaptation planning to begin immediately. Author Keywords: Adaptation Planning, Climate Change, Extreme Weather Events, Flood Planning, Simulation Modelling
ADHD Symptomatology Across Adulthood
Objective: To improve on several methodological issues and research gaps regarding current literature investigating the stability of ADHD symptomatology across adulthood and relationships between the two core ADHD symptom dimensions (i.e., inattention and hyperactivity-impulsivity) and multiple life outcomes in adults. Method: A large sample of postsecondary students were initially assessed for ADHD symptomatology using the Conners’ Adult ADHD Rating Scale (CAARS). Six years later, academic success was assessed using students’ official academic records (e.g., final GPAs and degree completion status), and fifteen years later, participants were re-assessed using the CAARS and several measures of life success (e.g., relationship satisfaction, career satisfaction, and stress levels). Results: Inattention and hyperactivity-impulsivity symptoms showed strong stability across the 15-year period. Additionally, greater inattention symptoms during emerging adulthood and early middle adulthood were consistently associated with poorer life success (e.g., lower GPAs, poorer relationship and career satisfaction), particularly for men. Associations for hyperactivity-impulsivity symptoms were less consistent. Conclusion: ADHD symptomatology can be conceptualized as a stable, dimensional trait across adulthood, with robust associations with measures of life success. Author Keywords: academic success, ADHD, adults, job satisfaction, relationship satisfaction, stability
ASSESSING THE IMPACT OF ATMOSPHERIC DEPOSITION AND HARVEST INTENSITY ON SOIL ACIDITY AND NUTRIENT POOLS IN PLANTATION FORESTS
The objective of this thesis was to assess the influence of anthropogenic sulphur (S) and nitrogen (N) deposition, and harvesting on soil acidity and calcium (Ca2+), magnesium (Mg2+), potassium (K+) and N soil pools in plantation forest soils in Ireland. The response to reductions in anthropogenic S deposition was assessed using temporal trends in soil solution chemistry at two long-term monitoring plots--one on a blanket peat, the other on a peaty podzol. At the peat site, there was little evidence of a response to reductions in throughfall non marine sulphate (nmSO42-) and acidity; soil water acidity was determined by organic acids. In addition, temporal variation in soil water did not respond to that in throughfall. In the podzol, reductions in anthropogenic S and H+ deposition led to a significant improvement in soil water chemistry at 75 cm; pH increased and total aluminum (Altot) concentrations declined. The impact of harvest scenarios on exchangeable Ca2+, Mg2+ and K+ pools was assessed using input-output budgets at 40 sites (30 spruce, 10 pine). Harvest scenarios were stem-only harvest (SOH), stem plus branch harvest (SBH) and stem, branch and needle harvest (whole-tree harvesting; WTH). Average K+ and Mg2+ budgets were positive under these scenarios. However, exchangeable K+ pools were small and due to uncertainty in K+ budgets, could be depleted within one rotation. Average Ca2+ budgets for spruce were balanced under SOH, but negative under SBH and WTH. Nitrogen deposition was high, between 5 and 19 kg N ha-1 yr-1, but was balanced by N removal in SOH. However, N budgets were under SBH and WTH, indicating that these harvesting methods would lead to depletion of soil N over the long-term. Finally, monitoring of N cycling at a spruce plot indicated that N deposition was contributing to large NO3- leaching, and as such the site was N saturated. However, N cycling did not fit the criteria of the N saturation hypothesis; instead leaching was directly related to N deposition and supported the model of kinetic N saturation. Author Keywords: acidic deposition, base cations, input-output budgets, Ireland, nitrogen, whole-tree harvesting
Abject Utopianism and Psychic Space
This dissertation utilizes the psychoanalytic theories of French psychoanalyst Julia Kristeva as a lens through which to read the novels of American author Samuel R. Delany. I argue that concepts proper to Kristeva's work--namely abjection and/or the abject--can provide a way to think what it might mean to be utopian in the 21st century. Delany's novels are received historically, which is to say his work speaks from a certain historical and cultural viewpoint that is not that of today; however, I claim that his novels are exceptional for their attempts to portray other ways of being in the world. Delany's novels, though, contain bodies, psychologies, and sexualities that are considered abject with respect to contemporary morality. Nonetheless, this dissertation argues that such manifestations of abject lived experience provide the groundwork for the possibility of thinking utopianism differently today. Throughout, what I am working toward is a notion that I call Abject Utopianism: Rather than direct attention toward those sites that closely, yet imperfectly, approximate the ideal, one should commit one's attention to those sights that others avoid, abscond, or turn their nose up at in disgust, for those are the sites of hope for a better world today. Author Keywords: Abject, Delany, Kristeva, Literary Criticism, Psychoanalysis, Utopia
Absorbance and Fluorescence Characteristics of Dissolved Organic Matter in North Atlantic, Pacific and Arctic Oceans
This thesis was designed to quantify absorbance and fluorescence characteristics of dissolved organic matter (DOM) in North Atlantic, Pacific and Arctic Oceans. DOM was described in water masses of distinct sources and formation pathways as well as in regions where environmental forcings such as deep water upwelling, enhanced biological activity and receipt of freshwater discharge were prevalent. Influence of sea ice on DOM in Beaufort Sea mixed layer (0 to 30 m) seawater was investigated based on sea ice extent as well as freshwater fractions of meteoric (fmw) and sea ice melt water (fsim) calculated from oxygen isotope ratio (δ18O). The effect of DOM exposure to simulated solar radiation was also assessed to determine the resilience of fluorescent fractions of DOM to photodegradation. This research aims to further our ability to trace DOM in marine environments and better understand its transformation pathways and predict its fate as part of the oceanic carbon cycle in a changing climate. Author Keywords: Absorbance, Arctic Ocean, Dissolved organic matter, Fluorescence, Parallel Factor Analysis, Sea Ice
Abundance and Distribution of Microplastics in Lake Scugog Catchment, Ontario
Plastic pollution is a growing concern, owing to its durability, ubiquity, and potential health impacts. The overall objective of this study was to assess the abundance and distribution of microplastics within Lake Scugog catchment, Ontario. This was fulfilled through two tasks (i) the development of a microplastic particle budget for the lake catchment, and (ii) the determination of the dry deposition of atmospheric microplastics in Port Perry, Ontario. The total input of microplastics into Lake Scugog (atmospheric deposition and stream inflow) was 2491 x106 mp/day, while the output (lake outflow and sedimentation) was 1761 x106 mp/day, suggesting that 29% of inputs were retained in the lake. The dry deposition of microplastics in Port Perry was 1257 mp/m2/day, which was high when compared to bulk deposition (37 mp/m2/day) in the same area. By quantifying the major pathways of microplastics better management techniques can be implemented. Author Keywords: Catchment, Dry Deposition, Microplastics, Ontario, Particle Budget, Plastic pollution
Academic Efficiency
Universities produce a significant and increasing share of basic research that is later commercialized by firms. We argue that the university's prominence as a producer of basic research is the result of a differential efficiency in research production that cannot be replicated by firms or individual agents - teaching. By using research accomplishments to signal knowledge and attract tuition-paying students, universities are uniquely positioned to undertake certain types of research projects. However, in a market for innovation without patent rights, a significant and increasing number of basic research projects, that are social welfare improving, cannot be initiated by firms or universities. The extension of patent rights to university-generated research elegantly redresses this issue and leaves us to ponder important questions about the future of our innovation-driven economies. Author Keywords: Innovation, Intellectual Property Rights, Research, Science Technology and Innovation Policy
Academic Procrastination, Self-Regulation, Anxiety and Personality (ASAP)
Academic procrastination is analogous to a common cold: pervasive and with no established cure. Students experience repercussions that are not inclusive to academic performance, but rather, are experienced across mental, physical, social and emotional domains as well. While this necessitates treatment, much of the behaviour has yet to be explained. In the current study, a state approach was integrated to explore procrastination in terms of the Yerkes-Dodson paradigm. Procrastination was hypothesized to arise for one of two reasons: students are either too low or too high in anxiety. A sample of 847 Ontario undergraduate students completed measures of procrastination, state-anxiety, personality, and self-regulation. Results suggest 88% of students procrastinate regularly, and contrary to what was hypothesized, procrastination and anxiety were linearly related. Independent t-tests establish that relative to non-procrastinators, procrastinators are significantly more emotionally and biologically dysregulated and less socially integrated. Factor analysis demonstrated three central reasons contributing to procrastination, which were used as the basis to establish types of procrastination: social (n=61), self-doubt (n=70) and low-energy (n=76) procrastinators. Results indicate divergences across procrastination type with respect to personality as well as biological, affective and social domains. Findings also inform that the expression of procrastination, varies across student. Overall, findings suggest that academic interventions should acknowledge and address the variability among procrastinators. Author Keywords: ACADEMIC PROCRASTINATION, ANXIETY, PERSONALITY, SELF-REGULATION
Achieving Equity in Mathematics Education
Little thought is given to how equitable mathematics would better the lives of those marginalized, or how the increased inclusion of marginalized voices improves the practice of mathematics. The purpose of this narrative research is to explore students’ voices and analyze aspects of math identity: the reported beliefs and practices of a group of elementary urban students who identify as Black/Brown. Understanding voice through counter-narrative is a methodology for the equitable practice of teaching/learning mathematics. CRRP describes participants engaged in the metacognitive task of writing untold stories as it relates to their beliefs, practices, and experiences in mathematics learning. The findings offer meaningful and appropriate insights to math educators about student competency, belongingness, and agency. Keywords: Black and Brown, marginalized students, student engagement, math identity, mathematical competence, sense of belonging to mathematics, mathematical agency, gateway, gatekeeper, fixed mindset, growth mindset, STEM pipeline, counter narrative. Author Keywords: Black and Brown, marginalized students, mathematical competence, math identity, sense of belonging to mathematics, student engagement
Acidification of lakes in northern Saskatchewan
The emission of acid precursors by large point sources in Western Canada (such as the Athabasca Oil Sands Region) has prompted studies into the possible impact to downwind aquatic and terrestrial ecosystems. Sensitivity of catchments to acidic deposition was estimated for the total lake population of northern Saskatchewan (n=89,947) using regression kriging. Under the Steady State Water Chemistry model, a range of 12-15% of the total catchment population was predicted to be in exceedance of critical loads under 2006 deposition levels and 6% of catchments were estimated to be very sensitive (pH below 6 and acid neutralizing capacity, alkalinity, calcium below 50 eqL-1). Temporal changes in soil and water chemistry estimated for 18 Alberta and Saskatchewan catchments using the Very Simple Dynamic and PROFILE models showed that changes in soil base saturation and lake acid neutralizing capacity between 1850 and 2100 were slight, declining 0.8% and 0.9% by 2012, respectively. Author Keywords: acidification, critical loads, exceedance, PROFILE, regression kriging, VSD
Active layer thermal regime in subarctic wetlands at the southern edge of continuous permafrost in Canada
The fine-scale controls of active layer dynamics in the subarctic at the southern edge of continuous permafrost are currently poorly understood. The goal of this thesis was to understand how environmental conditions associated with upland tundra heath, open graminoid fen, and palsas/peat plateaus affected active layer thermal regime in a subarctic peatland in northern Canada. Indices of active layer thermal regime were derived from in-situ measurements of ground temperature and related to local measurements of air temperature, snow depth, and surface soil moisture. Active layer thaw patterns differed among landforms, with palsas and tundra heath having the least and greatest amount of thaw, respectively. Tundra heath thaw patterns were influenced by the presence of gravel and sandy soils, which had higher thermal conductivity than the mineral and organic soils of fens and palsas. Vegetation also influenced thaw patterns; the lichen cover of palsas better protected the landform from incoming solar radiation than the moss, lichen, and low-lying shrub cover of upland tundra heath, thus allowing for cooler ground temperatures. Air temperature was the most significant predictor of active layer thermal regime. Surface soil moisture varied among landforms and greater surface soil moisture reduced the amount of active layer thaw. These findings improved understanding of how landform and climate can interact to affect the active layer. Author Keywords: Active layer thermal regime, Active layer thickness, Climate change, Peatland, Permafrost, Subarctic

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Format: 2024/03/28