Graduate Theses & Dissertations

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Responses of Primary Producers and Grazers to Silver Nanoparticle Exposure
The increasing production and use of silver nanoparticles (AgNPs) raise concerns on environmental exposure and impact. A large scale in situ enclosure study was conducted at the Experimental Lakes Area to determine the effect of AgNPs on natural phytoplankton and zooplankton communities. This study investigated AgNPs of varying concentrations (4, 16 and 64 μg/L), dosing regimens (chronic vs. pulse), and capping agents (poly-vinyl pyrrolidone vs. citrate). Phytoplankton communities were influenced only by the natural limnological properties of the system signifying tolerance to AgNPs. Zooplankton community structure significantly changed with AgNP concentration and dosing regimen indicating AgNP sensitivity. A microcosm study investigating the effect of AgNPs and phosphorus-dosed periphyton before and after grazing by two benthic invertebrate species (snails and caddisfly larvae) showed reduced periphyton stoichiometry with AgNP exposure. Grazers foraged less on silver dosed periphyton indicating a preferential choice in food quality. Phosphorus reduced the detrimental effects of AgNPs across all conditions. These studies verify the need for in situ experimental designs to fully investigate the effects of AgNPs and their interaction with environmental factors, multiple species assemblages, and across trophic levels. Author Keywords: benthic invertebrate, Experimental Lakes Area, periphyton, phytoplankton, silver nanoparticles, zooplankton
Analyzing agricultural decision making in the Late Roman Empire
In the Roman World, at least 80% and up to 95% of the population lived and worked in a rural environment, driving the agronomic economy of the empire. During the Late Roman Empire (AD 300-600), there were a number of widespread political, social, and economic changes faced by the people who made up the empire. Through all these changes, the empire maintained its tax collection and households maintained agricultural production. I will be examining settlement in the rural region of Isauria (Rough Cilicia) to understand the Late Roman agricultural production in a rural environment. This thesis focuses on the decision making that all economic levels of households would face when producing goods within this Late Roman Economy. Using an economic theory of the peasant economy, I develop a framework through which to view the agronomic production of the Late Roman Period which I use to understand the household as an agent. Author Keywords: Ancient Economy, Isauria, Late Roman, Peasant Economy, Roman Economy
Conservation Genetics of Woodland Caribou in the Central Boreal Forest of Canada
Maintaining functional connectivity among wildlife populations is important to ensure genetic diversity and evolutionary potential of declining populations, particularly when managing species at risk. The Boreal Designatable Unit (DU) of woodland caribou (Rangifer tarandus caribou) in Ontario, Manitoba, and Saskatchewan has declined in southern portions of the range because of increased human activities and has been identified as 'threatened' by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). In this dissertation, I used ten microsatellite DNA markers primarily from winter-collected fecal samples to delineate genetic structure of boreal caribou in declining portions of the range and increase understanding of the potential influence of the non-threatened Eastern Migratory DU of woodland caribou on genetic differentiation. Eastern migratory caribou are characterized by large home ranges compared to boreal caribou and migrate seasonally into portions of the Boreal DU range. A regional- and local-scale analysis using the spatial Bayesian clustering algorithm in program TESS delineated four regional clusters and 11 local clusters, with the majority of local clusters occurring along the southern periphery of the range. One of those clusters in Ontario corresponded spatially with the seasonal overlap of boreal and eastern migratory caribou and was characterized by substantial admixture, suggesting that the two DUs could be interbreeding. Next, I decoupled the impacts of historical and contemporary processes on genetic structure and found that historical processes were an important factor contributing to genetic differentiation, which may be a result of historical patterns of isolation by distance or different ancestry. Moreover, I found evidence of introgression from a currently unsampled population in northern Ontario, presumably barren-ground caribou (R. t. groenlandicus). Finally, because our analysis suggested recent processes were also responsible for genetic structure, I used a landscape genetics analysis to identify factors affecting contemporary genetic structure. Water bodies, anthropogenic disturbance, and mobility differences between the two DUs were important factors describing caribou genetic differentiation. This study provides insights on where conservation and management of caribou herds should be prioritized in threatened portions of the boreal caribou range and may have implications for future delineation of evolutionarily significant units. Author Keywords: boreal forest, genetic structure, landscape genetics, microsatellite DNA, Rangifer tarandus, woodland caribou
Investigation of Using Phase Change Materials for Thermal Energy Storage in Adiabatic Compressed Air Energy Storage
There is an increasing global need for grid scale electrical energy storage to handle the implementation of intermittent renewable energy sources. Adiabatic compressed air energy storage is an emerging technology with similar performance to pumped hydro except it has the issue of heat loss during the compression stage. Previously, it has been considered to use sensible heat storage materials to store the heat created by compression in a thermal energy storage unit until energy is required, and then transfer the heat back to the air. This research proposes to instead use phase change materials to store the heat of compression, as this will reduce entropy generation and maximize roundtrip exergy efficiency. Different configurations and placements of the phase change materials are considered and exergy analyses are presented. The thermodynamic equations are derived and optimal setup conditions including amount of latent heat and melting temperatures are calculated. Author Keywords: Compressed Air Energy Storage, Energy Storage, Exergy, Phase Change Materials
Flavohemoglobin expression in Giardia intestinalis exposed to nitrosative stress
The parasitic protist Giardia intestinalis lacks most heme proteins yet encodes a flavohemoglobin (gFlHb) that converts nitric oxide to nitrate and likely protects the cell from nitrosative stress. In this work an antibody raised against gFlHb was used to examine both changes in gFlHb expression levels and intracellular localization in Giardia in response to nitrosative stress. Giardia trophozoites exposed to stressors which either directly release nitric oxide (diethyltriamine NONOate, 1 mM) or are sources of other reactive nitrogen intermediates (sodium nitrite 20 mM or S-nitrosoglutathione, 1 or 5 mM) exhibited a 2 to 9-fold increase of gFlHb after 24 hours. Increased expression levels of gFlHb were detectable by 8 hours in S-nitrosoglutathione and diethyltriamine-NONOate-treated trophozoites, and by 12 hours after sodium nitrite exposure; these differences were likely due to differences in the rates of release of RNS from these compounds. In addition to a band of the expected size for gFlHb (52 kDa), western blots detected a second, higher molecular weight band (72 kDa) with comparable or higher intensity upon treatment with these RNS donors, which is consistent with sumoylation of gFlHb. Immunofluorescence microscopy of Giardia trophozoites detected gFlHb diffused throughout the cytoplasm and more punctuated staining along the cell membrane and between the nuclei. The punctuated staining may be due to the association of gFlHb with either peripheral vacuoles or basal bodies. Author Keywords: Flavohemoglobin, Giardia intestinalis, Nitrosative stress
Understanding the establishment of Typha spp. in North America using population genetics and common garden studies
There are three cattail (Typha) taxa in Canada: T. latifolia (native), T. angustifolia (introduced), and their hybrid T. x glauca. The latter is invasive in regions around the Laurentian Great Lakes, and I investigated the potential role that commercial suppliers may be playing in the introduction of non-native Typha by comparing genotypes of North American, European, and commercially available plants. I found that Ontario garden centres are importing both hybrids and non-native lineages of T. angustifolia into Canada, but was unable to identify the provenance of T. latifolia. I also investigated the possibility that the hybrid cattail leaf litter shade and leachate influences germination and early growth of the parental species of the hybrids. Using three common garden experiments, I found that T. x glauca leaf litter suppresses germination rates of the three taxa. In the early seedling growth experiment, plant performance varied by taxa, and for the competition experiment there were no intra- or interspecific competition or treatment effects on the performance of plants. Overall, my research identified a potential mechanism allowing T. x glauca to dominate wetlands, and also shows that non-native lineages are being introduced into Canada through commercial trade Author Keywords: Competition, Germination, Non-native lineages, Plant nurseries, Seedling Growth, Typha spp.
Long-term Financial Sustainability of China's Urban Basic Pension System
Population aging has become a worldwide concern since the nineteenth century. The decrease in birth rate and the increase in life expectancy will make China’s population age rapidly. If the growth rate of the number of workers is less than that of the number of retirees, in the long run, there will be fewer workers per retiree. This will apply great pressure to China’s public pension system in the next several decades. This is a global problem known as the “pension crisis”. In this thesis, a long-term vision for China’s urban pension system is presented. Based on the mathematical models and the projections for demographic variables, economic variables and pension scheme variables, we test how the changes in key variables affect the balances of the pension fund in the next 27 years. This thesis applies methods of deterministic and stochastic modeling as well as sensitivity analysis to the problem. Using sensitivity analysis, we find that the pension fund balance is highly sensitive to the changes in retirement age compared with other key variables. Monte Carlo simulations are also used to find the possible distributions of the pension fund balance by the end of the projection period. Finally, according to my analysis, several changes in retirement age are recommended in order to maintain the sustainability of China’s urban basic pension scheme. Author Keywords: China, demographic changes, Monte Carlo simulation, pension fund, sensitivity tests, sustainability
Class Struggle, The Communist Party, and the Popular Front in Canada, 1935-1939
This thesis is an attempt to provide a critical history of the Communist Party of Canada (CPC) during the Popular Front era, roughly November 1935 to September 1939. This study contains a detailed examination of the various stages of the Popular Front in Canada (the united front, the height of the Popular Front, and the Democratic front), with special attention paid to the CPC’s activities in: the youth movement, the labour movement, the unemployed movement, the peace movement, and the anti-fascist movement. From this I conclude that the implementation of the Popular Front, the transformation of the CPC from a revolutionary party to a bourgeois party, was not a smooth process, but instead was punctuated and resisted by elements within the CPC in what can be considered a process of class struggle internal to the CPC itself. Author Keywords: Canada, communism, Great Depression, labour, Popular Front, socialism
Calcium in the Muskoka River Watershed- Patterns, trends, the potential impact of forest harvesting and steps toward an ecosystem approach to mitigation
Decreasing lake calcium (Ca) concentration, in lakes located in base poor catchments of the Muskoka River Watershed (MRW) in south-central Ontario, is a well- established acid-rain driven legacy effect threatening the health and integrity of aquatic ecosystems that can be compounded by additional Ca removals through forest harvesting. The objectives of this thesis were to assess patterns and temporal trends in key water chemistry parameters for a set of lakes in forested catchments in the MRW in south- central Ontario, to predict the pre-industrial steady state lake Ca concentration and the potential impact of harvesting on lake Ca levels in lakes located in managed MRW Crown forests, and to assess potential effects of various mitigation strategies in Ca depleted managed forests. Mean lake Ca (mg L-1) in 104 lakes across the MRW have decreased by 30% since the 1980's with the rate of decrease slowing over time. Mean Lake SO4 (mg L-1), and Mg (mg L-1) concentration also decreased significantly with time (37% and 29%, respectively) again with a declining rate of decrease, while mean lake pH and DOC increased significantly between the 1980's and the 1990's (16% and 12%, respectively) but exhibited no significant pattern after that. Principal components and GIS spatial analyses of 75 lakes with data from 2011 or 2012 water seasons suggested that smaller lakes, at higher elevation in smaller catchments with higher runoff and minimally impacted by the influence of roads and agriculture are associated with lower Ca concentrations and thus are the lakes at risk of amplified Ca depletion from forest harvesting. Spatial analyses of harvested catchments indicated that, under the proposed 10 year land forest management cut volumes, 38% of 364 lakes in the MRW will fall below the critical 1 mg L-1 Ca threshold compared with 8% in the absence of future harvesting. With respect to potential mitigation measures, soil pH and foliar Ca were indicated by meta-analysis to be more responsive to lime addition studies while soil base saturation and tree growth appeared more responsive to wood-ash addition. Future research should address the spatial extent of lakes at risk and identify when critical levels will be reached under harvesting regimes. Further investigation into the use of Ca-addition as a tool for managing the cumulative effects of past, present and future stressors is recommended. Author Keywords: calcium, harvesting, lakes, lime, Muskoka River Watershed, wood-ash
MSHKIKENH IKWE NIIN (I am Tutle Woman)
This dissertation offers the dibaajimowin (personal story) of my beading project, which I undertook to understand the enactment of Anishinaabe women’s knowledge in graduate research. Framed through the concept of a collective self, which is embedded within the Anishinaabe traditions of storytelling and beading, and drawing further from the aesthetics, processes, and teachings of these traditions so that I proceed in a good way, I am able to tell a story that is wholly Anishinaabe. Through the symbolic literacy present within the pieces of beadwork entitled:”Turtle Woman,” “Turtle Woman Meets Grandmother Moon,” “Turtle Woman Marries a Beaver,” and “Turtle Woman Slays the Big Fish,” which I present in the second half of this story, I explore the relationship among Anishinaabe women’s knowledges, self, identity, power relations, allyship, sovereignty and good governance in graduate research. I conclude that if graduate research is framed as an extension of an Anishinaabe space, an ethics of responsibility emerges, setting the stage for graduate research that is rooted in responsibility, contributing to efforts of Anishinaabe sovereignty and community wellness. Overall through my conclusion, as well as the process that I employ, I make contributions in the areas of Indigenous thought, Indigenous methodologies, Indigenous governance, feminism, critical theory, pedagogy, and ally theory. Author Keywords: Anishinaabe, beadwork, Indigenous knowledge, Indigenous methodology, Indigenous women, sovereignty
Testing the Validity of Dental Calculus as a Proxy to Bone in Paleodietary Studies Using Stable Isotope Analysis
This study investigates the use of dental calculus for paleodietary studies using stable isotope analysis of a skeletal sample from the Greek colonial site of Apollonia Pontica, Bulgaria (5th to 3rd century BC). A sample of 27 individuals was used to examine the δ13C and δ15N values of paired dental calculus and bone samples, and the dental calculus was analyzed as separate organic and inorganic components. No significant correlation was found between the δ13C values of either the bone collagen and organic dental calculus samples, or the bone apatite and inorganic dental calculus samples. A significant correlation was found between the δ15N values of the bone collagen and organic dental calculus samples; however, the reason for this correlation is unclear. A greater range of variation in the δ13C and δ15N values was found in the organic dental calculus samples compared to the respective bone collagen samples. These results suggest that dental calculus is not an appropriate proxy to bone for paleodietary studies using stable isotope analysis and that any dietary signal is clouded by other data. The oral microbiome is considerably diverse and is the most probable explanation for the great range of stable isotope values obtained from dental calculus. A significant, strong correlation was found between the C/N ratios and δ15N values of the organic dental calculus samples, suggesting that the lowest C/N ratios and δ15N values depict deposits with the least bacterial alteration. Author Keywords: carbon, dental calculus, nitrogen, paleodietary studies, Social Sciences, stable isotopes
Native Art as seen through Native Eyes
Since the end of the Second World War, artists of Native descent have engaged with the Fine Art world where their work has come to be placed in the category of Native art. As a result of my journey, I have come to realize that in the Fine Art world the term Native art tends to be associated with the practices of our ancestors in times past obscuring our contemporary nature. In the present day context, however, I see an evolution and will tell the stories of the artists I met, who became a part of my life and thus a part of my narrative to point out that the voices of contemporary artists of Native descent, when speaking of their work, demonstrate a modern form of Native creativity, pride and joy that needs to be properly recognized. While Native artists do respect our traditions and do deal with issues of importance to our communities, they also create their artwork using sophisticated and modern techniques. It is up to us to make our contemporary nature known far and wide. A storytelling approach based on the Michael Thrasher Medicine Wheel Teachings is employed to present the voices of our contemporary artists of Native descent who when speaking of their work create a rich and vibrant story of Native creativity, pride and joy. Author Keywords: Culture, Elder, Indigenous Knowledge, Native Art, Storytelling

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Format: 2024/03/29