Graduate Theses & Dissertations

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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
effects of heat dissipation capacity on avian physiology and behaviour
In endotherms, physiological functioning is optimized within a narrow range of tissue temperatures, meaning that the capacity to dissipate body heat is an important parameter for thermoregulation and organismal performance. Yet, experimental research has found mixed support for the importance of heat dissipation capacity as a constraint on reproductive performance. To investigate the effects of heat dissipation capacity on organismal performance, I experimentally manipulated heat dissipation capacity in free-living tree swallows, Tachycineta bicolor, by trimming feathers overlying the brood patch, and monitored parental provisioning performance, body temperature, and offspring growth. I found that individuals with an enhanced capacity to dissipate body heat (i.e., trimmed treatment) provisioned their offspring more frequently, and reared larger offspring that fledged more consistently. Although control birds typically reduced their nestling provisioning rate at the highest ambient temperatures to avoid overheating, at times they became hyperthermic. Additionally, I examined inter-individual variation in body temperature within each treatment, and discovered that body temperature is variable among all individuals. This variability is also consistent over time (i.e., is repeatable), irrespective of treatment. Further, I found that individuals consistently differed in how they adjusted their body temperature across ambient temperature, demonstrating that body temperature is a flexible and repeatable physiological trait. Finally, I used a bacterial endotoxin (lipopolysaccharide) to examine the regulation of body temperature of captive zebra finches (Taeniopygia guttata) during an immune challenge. Exposure to lipopolysaccharide induces sickness behaviours, and results in a fever, hypothermia, or a combination of the two, depending on species and dosage. I asked what the relative role of different regions of the body (bill, eye region, and leg) is in heat dissipation/retention during the sickness-induced body temperature response. I found that immune-challenged individuals modulated their subcutaneous temperature primarily through alterations in peripheral blood flow, particularly in the legs and feet, detectable as a drop in surface temperature. These results demonstrate that the importance of regional differences in regulating body temperature in different contexts. Taken together, my thesis demonstrates that heat dissipation capacity can affect performance and reproductive success in birds. Author Keywords: body temperature, heat dissipation, tree swallow, zebra finch
relationship of policy aims and implementation
Background: Ontario’s Ministry of Health and Long Term Care (MOHLTC) claims people with mental illnesses/addictions need improved care/overuse emergency departments. MOHLTC expects Coordinated Care Planning (CCP, teams of mental/physical health professionals, social workers and informal caregivers) to improve care and lower emergency department returns/healthcare costs. CCPs are directed by policies, Smith’s “problematics,” or Deleuze’s “expressions,” supposedly reflecting “contents”/“everyday worlds.” Research Question: How do Ontario health/allied professionals come together with a person with mental illness/addictions and informal caregiver(s) to address health needs through a CCP? Method: 1) Analyzed CCP policies; generated questions about creation/implementation. 2) Interviewed eight professionals about interpreting/enacting policies. 3) Connected interview data to policies. Findings: Opportunities for fragmentation exist in gaining consent; determining eligibility; persons in care, informal caregivers and professionals’ participation; person-centeredness; “shame-free” environments; health literacy; records of medications. Conclusion: CCP participants need to minimize fragmentations which takes time, space, money; creates contradictions in lowering costs/improving care. Author Keywords: Addiction, Dual Diagnosis, Health Care Policy, Institutional Ethnography, Integrated Health Care, Mental Illness
Effects of flooding on nutrient budgets and ecosystem services
Increases in flooding due to anthropogenic influences such as climate change and reservoir creation will undoubtedly impact aquatic ecosystems, affecting physical, chemical, and biological processes. We used two approaches to study these impacts: a whole-ecosystem reservoir flooding experiment and a systematic literature review. In the whole-ecosystem experiment, we analyzed the impact of flooding on nutrient release from stored organic matter in an upland forest. We found that flooded organic matter produced N (nitrogen) and P (phosphorus), but that more N was released relative to P, increasing the N:P ratio over time. In the systematic literature review, we linked small (<10 year recurrence interval) and extreme (>100 year recurrence interval) floods to changes in 10 aquatic ecosystem services. Generally, extreme floods negatively impacted aquatic ecosystem service provisioning, while small floods contributed positively. Overall, we found that flood impacts vary depending on ecosystem properties (organic matter content) and flood characteristics (magnitude). Author Keywords: ecosystem services, flooding, nutrients, reservoirs, rivers
"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
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.
Following ininaahtigoog Home
Indigenous peoples’ sur-thrivance in global, settler colonial, historical, and nation-specific economic contexts is a broadly studied subject that fails to emphasize Indigenous economic sovereignty. Indigenous knowledges regarding the land-based relationalities which formulate an aspect of Indigenous economic sovereignty is lacking. So too is knowledge on Indigenous womxn’s land and water-based relationalities from which her economic sovereignty flows. Writing within and for Anishinaabeg sur-thrivance in Anishinaabewaki, this research examines Anishinaabeg womxn’s relationship with the sugar bush during the spring harvest as a site of gendered nation-specific economic sovereignty. Epistemicide has attenuated land-based knowledges in gendered ways; and, missionary and settler colonial processes in Canada, the U.S., and within Anishinaabeg communities have alienated Anishinaabeg womxn from inherent land and water-based relationships. By employing an Anishinaabeg methodology of “critically returning to ourselves” that is oriented towards Anishinaabe approaches to history and Anishinaabe ways of seeing history as worlds, this research recovers information about womxn’s sugar bush relationships. This recovery begins with literary, documentary, and oral sources. Through anishinaabe feminist interpretation, I reveal that womxn’s sugar bush relationships engender whole worlds that are animated and generated by her legendary connections with the natural and spiritual world, her social-economic commitment and savvy, and her enduring labour. I further interpret that her connections, her savvy, and her labour is mediated with variable aspects of settler colonial gendered influences such as patriarchy, omnipresent heterosexuality and/or gender binaries, marriage, class, and values attributed to womxn that are inconsequential to sur-thriving in land and water-based worlds. In conclusion this research tells three distinct, but connected, “sticky and sweet [story] strands” which illuminate the significance, beauty, complexity, and un-romance of Anishinaabeg womxn’s relationship with the sugar bush. Simultaneously, it prompts Anishinaabeg to reflect on the worlds we have lived in, are living in now, and want to create in terms of land-based relationships and relationalities. In effort to disrupt and bring attention to the restrictions and distortions that several hundred years of missionary, settler colonial, (hetero)patriarchal, heterosexist, and capitalist forces have had on Anishinaabeg gender and relational formations, my method in writing (i.e. spelling) is to prompt consciousness of gender and relational fluidity and diversity. This approach presses for Anishinaabeg committed orientation towards the necessities and possibilities of correcting and transforming imposed and internalized settler gender and relational formations and structures. This research builds on a body of literature about Indigenous womxn’s relationship with land and water in Turtle Island in order to signify and illuminate Anishinaabeg womxn’s dynamic and varied relationship with the sugar bush. It contributes to Indigenous research methodology, Indigenous and Anishinaabeg women’s history, Indigenous women’s labour, and Indigenous literary studies. Author Keywords: Anishinaabeg Studies, economic sovereignty, Indigenous feminism, Indigenous relationship with land, Indigenous women, sugar bush
Range-Based Component Models for Conditional Volatility and Dynamic Correlations
Volatility modelling is an important task in the financial markets. This paper first evaluates the range-based DCC-CARR model of Chou et al. (2009) in modelling larger systems of assets, vis-à-vis the traditional return-based DCC-GARCH. Extending Colacito, Engle and Ghysels (2011), range-based volatility specifications are then employed in the first-stage of DCC-MIDAS conditional covariance estimation, including the CARR model of Chou et al. (2005). A range-based analog to the GARCH-MIDAS model of Engle, Ghysels and Sohn (2013) is also proposed and tested - which decomposes volatility into short- and long-run components and corrects for microstructure biases inherent to high-frequency price-range data. Estimator forecasts are evaluated and compared in a minimum-variance portfolio allocation experiment following the methodology of Engle and Colacito (2006). Some consistent inferences are drawn from the results, supporting the models proposed here as empirically relevant alternatives. Range-based DCC-MIDAS estimates produce efficiency gains over DCC-CARR which increase with portfolio size. Author Keywords: asset allocation, DCC MIDAS, dynamic correlations, forecasting, portfolio risk management, volatility
Perspectives on Poultry
The contemporary denigration of poultry combined with the intensification of industrialized animal agriculture has deepened divides between humans and poultry, creating a disconnect that holds implications for both parties and the sustainability of North American food systems. This study explores how people with poultry keeping experience perceive these animals, how their views are influenced and how these narratives may intersect with themes of sustainability. Surveys and interviews aimed at small flock keepers and commercial farmers within an area of Central Ontario revealed that poultry sentience was widely recognized among participants. Overall, this study’s findings disrupt commonly held notions that poultry are one-dimensional beings and highlight the mutual benefits that can come when the distance is lessened between humans and poultry. This research contends that reimagining human-poultry relationships could improve our ability to consider and challenge dominant systems that perpetuates unsustainable food production and negatively affects both animal and human life. Author Keywords: history poultry keeping, human-animal studies, human-poultry relationships, keeper attitudes, poultry sentience, sustainable food systems
Prescription Drugs
Medication used to treat human illness is one of the greatest developments in human history. In Canada, prescription drugs have been developed and made available to treat a wide variety of illnesses, from infections to heart disease and so on. Records of prescription drug fulfillment at coarse Canadian geographic scales were obtained from Health Canada in order to track the use of these drugs by the Canadian population. The obtained prescription drug fulfillment records were in a variety of inconsistent formats, including a large selection of years for which only paper tabular records were available (hard copies). In this work, we organize, digitize, proof and synthesize the full available data set of prescription drug records, from paper to final database. Extensive quality control was performed on the data before use. This data was then analyzed for temporal and spatial changes in prescription drug use across Canada from 1990-2013. In addition, one of major research areas in environmental epidemiological studies is the study of population health risk associated with exposure to ambient air pollution. Prescription drugs can moderate public health risk, by reducing the drug user's physiological symptoms and preventing acute health effects (e.g., strokes, heart attacks, etc.). The cleaned prescription drug data was considered in the context of a common model to examine its influence on the association between air pollution exposure and various health outcomes. Since, prescription drug data were available only at the provincial level, a Bayesian hierarchical model was employed to include the prescription drugs as a covariate at regional level, which were then combined to estimate the association at national level. Although further investigations are required, the study results suggest that the prescription drugs influenced the air pollution related public health risk. Author Keywords: Data, Error checking, Population health, Prescriptions
Modelling Request Access Patterns for Information on the World Wide Web
In this thesis, we present a framework to model user object-level request patterns in the World Wide Web.This framework consists of three sub-models: one for file access, one for Web pages, and one for storage sites. Web Pages are modelled to be made up of different types and sizes of objects, which are characterized by way of categories. We developed a discrete event simulation to investigate the performance of systems that utilize our model.Using this simulation, we established parameters that produce a wide range of conditions that serve as a basis for generating a variety of user request patterns. We demonstrated that with our framework, we can affect the mean response time (our performance metric of choice) by varying the composition of Web pages using our categories. To further test our framework, it was applied to a Web caching system, for which our results showed improved mean response time and server load. Author Keywords: discrete event simulation (DES), Internet, performance modelling, Web caching, World Wide Web
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

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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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