Graduate Theses & Dissertations

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Influence of nitrogen deposition on the vegetation community of Irish oak woodlands
In this study, the influence of N deposition on the vegetation community of semi-natural oak woodlands in Ireland was assessed through national and regional scale analysis of forest plot data. At both scales, Canonical Correspondence Analysis suggested that N deposition was a predictor of community composition, although site-specific soil characteristics were the strongest predictors of the species dataset. Threshold Indicator Taxon Analysis suggested that the vegetation community demonstrated the most change at 13.2 kg N ha-1 yr-1. While this change point falls within the current recommended critical load range for nutrient nitrogen for acidophilous oak dominated woodlands (10 to 15 kg N ha-1 yr-1), it is notable that 23% of species recorded had individual change points below this range, and could potentially be lost from this habitat if deposition increases. The results from this study suggest that, for acidophilous oak woodlands, habitat conservation policies should be unified with N emission reduction policies. Author Keywords: community composition, critical load, nitrogen depositioin, oak woodland, species richness, Taxon Indicator Threshold Analysis
Equilibria and distribution models of ionizing organic chemical contaminants in environmental systems
Ionizing organic chemicals are recognized as constituting a large fraction of the organic chemicals of commerce. Many governments internationally are engaged in the time-consuming and expensive task of chemical risk assessment for the protection of human and environmental health. There are standard models that are consistently used to supplement experimental and monitoring data in such assessments of non-ionizing organics by both government regulators and industry stakeholders. No such standard models exist for ionizing organics. Equilibrium distribution models, the foundational equations within multimedia environmental fate models for non-ionizing organics, were developed for the standard series of biphasic systems: air-water, particle-water, air-particle and organic-aqueous phases within living tissue. Multiple chemical species due to the ionization reaction were considered for each system. It was confirmed that, under select conditions, the properties of the neutral parent are sufficient to predict the overall distribution of the organic chemical. Complications due to biotransformation and paucity of identifiable equilibrium distribution data for ionizing organics limited the development of the model for living tissues. However, the equilibrium distributions of ionizing organics within this biotic system were shown to correlate with the abiotic sediment-water system. This suggests that the model developed for particle-water systems should be adaptable to the biotic system as model input and test data become available. Observational data for soil- and sediment- water systems, i.e., particle-water systems, allowed the development of a primarily non-empirical distribution equation for mono-protic acids; this model was almost entirely theoretically derived. The theoretical approach to model development allowed a quantitative assessment of the role of the neutral ion pair, resulting from the complexation of the organic anion with metal cations. To demonstrate the model's potential usefulness in governmental screening risk assessments, it was applied to a broad range of mono-protic organics including drugs and pesticides using standard property estimation software and generic inputs. The order-of-magnitude agreement between prediction and observation typical of the existing models of non-ionizing organics was generally achieved for the chemicals tested. The model was sensitive to the octanol-water partition coefficient of the most populous species. No calibration set was used in the development of any of the models presented. Author Keywords: bioconcentration, chemical equilibrium, environmental modelling, ionizing organic, sorption
Ontario's Aboriginal Education Strategy
Since 2007, Aboriginal education initiatives in Ontario have been supported by the Aboriginal Education Strategy (Strategy) under provincial Liberal governments. Using a comparative analysis, this thesis seeks to identify how the Strategy supports and/or does not support components of critical pedagogy to promote transformational learning for all students in Ontario's publicly funded schools. A brief historical timeline of Aboriginal education in Canada and the current situation of educational attainment for Aboriginal and non-Aboriginal peoples provides context for the thesis. Through an examination of policy documents and resources related to the Strategy, I identify both strengths and areas for improvement in the Strategy to meet expectations of critical pedagogy. Finally, I suggest recommendations to improve the Strategy in order to achieve its potential for the benefit of all students in Ontario's public schools. Author Keywords: Aboriginal students, Critical pedagogy, Education, Ontario, Policy
Heavy Rydberg Photo-dissociation Cross-section Calculations and Experimental Progress Towards Cold Collisions in Lithium
This thesis is divided into two parts, each of which supports constructing and using a lithium magneto-optical trap for cold collision studies: Part I One outgoing channel of interest from cold collisions is the production of ion pairs. We describe an effective method for calculating bound-to-continuum cross-sections for charged binary systems by examining transitions to states above the binding energy that become bound when the system is placed within an infinite spherical well. This approach is verified for ionization of a hydrogen atom, and is then applied to the heavy Rydberg system Li+...I-. Part II A wavemeter previously built in the lab is redesigned for increased reliability and ease of use by replacing the optical hardware with a rocker system, which can be aligned in mere minutes rather than half a day as was previously the case. The new wavemeter has been tested through saturated absorption spectroscopy of lithium. Author Keywords: cross-section, dissociation, lithium, magneto-optical trap, Michelson, wavemeter
Pursuing Different Policy Paths in Long-Term Care
Because federal funding for long-term care was not included as part of Canada's publicly-funded universal health care system, provincial governments have been free to determine how much, or how little, they will rely on the for-profit sector to meet the long-term care needs of their senior populations. The proportion of beds in the for-profit sector differs in each province, demonstrating that policy approaches to this type of care have developed according to distinct provincial political contexts. In this dissertation I explain why governments in two provinces, Manitoba and Ontario, have come to rely on the proprietary sector to markedly different degrees. While in the federation Manitoba stands out for its restrained reliance on this form of care, Ontario stands out for its exceptional dependence on commercial provision. In the chapters that follow I employ an historical institutionalist framework of analysis to explain why these neighbouring provinces initially pursued different policy paths in long-term care and how these paths have been sustained over time. Following an introductory chapter in which I explain the reasons for the marginalization of long-term care within national health policy making, I provide in-depth analysis of these case studies in policy divergence. I argue that contemporary policy differences between these neighbouring provinces cannot be understood in isolation from long-term historical processes. Focusing largely on the period from the 1960s to the 1990s, I emphasize that present differences in ownership are a reflection of the different constellation of actors, events, ideas and institutions that came together at critical junctures in time, and the lasting legacies that these early windows of opportunity for reform have had on subsequent rounds of long-term care policy-making. In each province, diverging ideas about the appropriate role of the for-profit sector in meeting the long-term care needs of an aging population rose to prominence on the political agenda. Over time, rigidities developed in each system, making it difficult for actors advocating for new directions in ownership to realize their ambitions. In both provinces policies put in place at earlier times greatly influenced future political dynamics, altered the guiding principles of government departments and policy makers, provided incentives for different interest group formations, and led to contrasting public expectations about the proper balance of the for-profit and non-profit sectors in long-term care provision. I conclude this dissertation by arguing that its findings can contribute in important ways to present discussions about long-term care reform in Canada generally and about the future role of for-profit providers specifically. Author Keywords: Comparative Politics, Health Policy, Historical Institutionalism, Long-Term Care, Path Dependency, Provincial Politics
HABITAT SELECTION AND LIFE-HISTORY TRAITS OF BREEDING BIRDS IN THE BOREAL-TUNDRA ECOTONE, WITH SPECIAL ATTENTION TO THE AMERICAN ROBIN (TURDUS MIGRATORIUS)
I investigated biodiversity of birds and vegetation associations along the boreal-tundra ecotone in Ivvavik National Park, Yukon Territory, and breeding adaptations used by American Robins (Turdus migratorius) at high latitudes. Twenty bird species were detected over three years using point-count surveys. Densities of American Robin, Dark-eyed Juncos (Junco hyemalis), and Yellow-rumped Warbler (Dendroica coronata) had positive relationships with tree and shrub density, whereas density of White-crowned Sparrows (Zonotrichia leucophrys) was negatively related to tree density. American Robins at this latitude raised only one brood, but females laid slightly larger clutches, the young fledged earlier, and pairs experienced higher nest-success than American Robins at more southerly latitudes. American Robins selected nest sites with high vegetation volume, at both the nest-site, and the nest-patch. This study is important for the first description of the bird community at this high latitude location, and describing how a species at the northern limit of the boreal forest has adapted to living with short-breeding seasons. Author Keywords: American Robin, Ivvavik National Park, Life History, Nest-stie selection, Northern limit
Gaagnig Pane Chiyaayong: Forever, We Will Remain, Reflections and Memories
ABSTRACT Gaagnig Pane Chiyaayong: Forever, We Will Remain Reflections and Memories: `Resiliency' Concerning the Walpole Island Residential School Survivors Group Theresa Turmel From 1830 to 1996, Canada pursued a policy of removing Indigenous children from their families and educating them in residential schools. In coming to terms with the harsh and abusive treatment they endured, many survivors from residential schools have formed organizations to support each other and to make their experiences known. This project is a result of a participatory, community-based partnership with one such group in southwestern Ontario, the Walpole Island Residential School Survivors Group (WIRSSG), many of whom attended Shingwauk Indian Residential School. Like most of the survivors of the WIRSSG, I am Anishinaabe but did not attend residential school. The survivors invited me to deeply listen to their life experiences in order to learn about their resiliency. Guided by traditional Anishinaabe teachings and using an Anishinaabe methodology, I interviewed thirteen survivors and considered their life stories within the context of the traditional Anishinaabe life cycle. In their descriptions of resiliency, what became clear to me was that they were describing life force energy. This life force energy is innate and holistic, and can be found within each of us. It manifests within all of our relations: land, animals, plants, ancestors and other people. The life force energy cannot be extinguished but can be severely dampened as was evident in the attempt to assimilate residential school students. From their accounts, we learn that students found ways to nurture their life force energy through relationships and acts of resistance. As they have continued on their life path, they have reclaimed their spirit and today, they are telling their stories and keeping this history alive for the benefit of future generations. Key words: Anishinaabe; Anishinaabe Mino-bimaadiziwin; Residential Schools; Aboriginal Residential School survivors; Indian Residential Schools; Indian Residential School survivors; life force energy; resilience; resiliency; resiliency theory; Walpole Island Residential School Survivors Group; Shingwauk; Shingwauk Indian Residential School Author Keywords: life force energy, residential school survivors, resiliency
War and Peace
The relationship between siblings is unique in both its history and duration across the lifespan. Previous relationship researchers have examined siblings in childhood, but few have explored this distinctive relationship in adulthood. In this study, the adult sibling relationship was explored from an attachment perspective to determine the effect of an individual's attachment on conflict and collaboration with siblings. As expected, secure attachment predicted negative associations with conflict and positive associations with collaboration whereas insecure attachment (fearful, preoccupied, and dismissing) predicted opposite patterns. Results were compared to the abundance of literature on romantic relationships and findings from this study provided support for the theory that siblings function as attachment figures in adulthood. Author Keywords: Attachment, Collaboration, Conflict, Relationships, Romantic partners, Siblings
"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
Identifying non-local individuals at the ancient Maya centre of Minanha, Belize through the use of strontium isotope analysis
Strontium isotope analysis has become an important tool in identifying non-local individuals at archaeological sites. For this study, tooth enamel samples were collected from 20 individuals from the ancient Maya centre of Minanha, Belize. These individuals date to periods spanning the formative occupation of the centre, as well as its fluorescence and protracted decline. The goal of this research was to investigate if non-local individuals played a role in Minanha's formation and fluorescence. The study utilised published strontium isotope maps from Belize and the Yucatán in order to establish local 87Sr/86Sr values. The values of the Minanha enamel samples (n = 20) fell predominantly outside of the expected strontium isotope range; this result seemed implausible and an alternative method was utilised to establish the local 87Sr/86Sr values. The outlier method identified 5/20 (25%) non-local individuals. All of the non-local individuals had 87Sr/86Sr values that coincided with published 87Sr/86Sr values reported from within 10 - 20 km of Minanha. However, some strontium isotope values also corresponded with 87Sr/86Sr values reported from regions >50 km away. The percentage of non-locals at Minanha is consistent with other Mesoamerican centres. This study emphasises the importance of collecting local baseline 87Sr/86Sr values from sites themselves, as 87Sr/86Sr values from neighbouring regions might not reflect local strontium isotope values. Author Keywords: Ancient Maya, bioarchaeology, migration, mobility, Vaca Plateau
Fractionation of Mercury Isotopes in an Aqueous Environment
Fractionation of mercury isotopes in an aqueous environment: Chemical Oxidation Dimitri Stathopoulos The study of fractionation patterns for the stable isotopes of mercury is a growing field. The potential for stable isotopes to trace mercury through the environment from pollution sources to sinks make the subject interesting to geochemists and useful to a wider audience. The purpose of this study is to measure the fractionation of mercury as it is oxidized in an aqueous medium. Samples in this study are prepared by chemically oxidizing different proportions of elemental mercury using four different oxidants. The oxidized portion is then separated from the elemental portion and an analysis of the isotope ratios for both portions is performed using a multicollector inductively coupled plasma mass spectrometer MC-ICP/MS. These isotope ratios are measured against the preoxidation isotope ratio to determine what if any change has occurred. From the findings of this work, it is now known chemical oxidation causes both mass dependent and mass independent fractionation. Mass dependent fractionation causes an enrichment of the heavier isotopes in the oxidized portion while the opposite is true for the elemental portion. Mass independent fractionation occurred only in the odd isotopes and causes a depletion of odd isotopes in the oxidized portion and enrichment in the elemental portion. These trends were found to be true for all oxidants tested as the pattern of fractionation does not change with varying oxidants. Author Keywords: Isotope, Mass Dependent, Mass Independent, Mercury, Oxidation
THE LIFE HISTORY STRATEGY, GROWTH, BODY CONDITION, AND DIET OF STOCKED AMERICAN EEL (Anguilla rostrata) IN THE UPPER ST. LAWRENCE RIVER AND LAKE ONTARIO
My study was primarily focused on the comparison of life history traits between stocked American eel and their naturally recruited conspecifics in Lake Ontario and the upper St. Lawrence River (USLR/LO). I found that stocked eels experienced faster annual growth than their naturally recruited conspecifics and were comprised of a greater proportion of males. These findings indicate that the life history patterns of American eel may be genetically predisposed. Additionally, my study served to characterize the diets of stocked American eel and examine possible associations between eel and prey size. The eels consumed a number of macroinvertebrate prey orders as well as fishes and macrocrustaceans, with the latter prey items being more prevalent in the diets of larger eel specimens. A disparity in eel growth and body condition was observed between two primary stocking locations and were likely attributable to differences in available forage and habitat. Lastly, growth, body condition, and stocked eel diet were compared between lentic and lotic habitats. Eels from lotic streams experienced slower annual growth and had reduced body condition, and their diets were comprised of smaller prey items. The results of this study suggest that the current stocking methods employed in the USLR/LO are not suitable to restore the natural recruitment of individuals that will exhibit desired life history traits. Author Keywords:

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Graduate student theses produced at Trent University. You may also browse theses and dissertations by year, program, or author.

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1973 - 2033
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