Graduate Theses & Dissertations

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Stoichiometric food quality affects responses of Daphnia to predator-derived chemical cues
While both resource quality and predator-derived chemical cues can each have profound effects on zooplankton populations and their function in ecosystems, the strength and nature of their interactive effects remain unclear. We conducted laboratory experiments to evaluate how stoichiometric food quality (i.e., algal carbon (C):phosphorus (P) ratios) affects responses of the water flea, Daphnia pulicaria, to predator-derived chemical cues. We compared growth rates, body elemental content, metabolic rates, life history shifts, and survival of differentially P-nourished Daphnia in the presence and absence of chemical cues derived from fish predators. We found effects of predator cues and/or stoichiometric food quality on all measured traits of Daphnia. Exposure to fish cues led to reduced growth and increased metabolic rates, but had little effect on the elemental content of Daphnia. Elevated algal C:P ratios reduced growth and body %P, increased respiration, and increased body %C. Most of the effects of predator cues and algal C:P ratios of Daphnia were non-interactive. In contrast, the declines in daphnid survival and related population growth rates that arose because of poor food quality were amplified in the presence of predator-derived cues. Our results demonstrate that stoichiometric food quality interacts with anti-predator responses of Daphnia, but these effects are trait-dependent and appear connected to animal life-history evolution. Author Keywords: Daphnia, ecological stoichiometry, indirect predator effects, life history, phosphorus, predator-prey relationships
Self-Organizing Maps and Galaxy Evolution
Artificial Neural Networks (ANN) have been applied to many areas of research. These techniques use a series of object attributes and can be trained to recognize different classes of objects. The Self-Organizing Map (SOM) is an unsupervised machine learning technique which has been shown to be successful in the mapping of high-dimensional data into a 2D representation referred to as a map. These maps are easier to interpret and aid in the classification of data. In this work, the existing algorithms for the SOM have been extended to generate 3D maps. The higher dimensionality of the map provides for more information to be made available to the interpretation of classifications. The effectiveness of the implementation was verified using three separate standard datasets. Results from these investigations supported the expectation that a 3D SOM would result in a more effective classifier. The 3D SOM algorithm was then applied to an analysis of galaxy morphology classifications. It is postulated that the morphology of a galaxy relates directly to how it will evolve over time. In this work, the Spectral Energy Distribution (SED) will be used as a source for galaxy attributes. The SED data was extracted from the NASA Extragalactic Database (NED). The data was grouped into sample sets of matching frequencies and the 3D SOM application was applied as a morphological classifier. It was shown that the SOMs created were effective as an unsupervised machine learning technique to classify galaxies based solely on their SED. Morphological predictions for a number of galaxies were shown to be in agreement with classifications obtained from new observations in NED. Author Keywords: Galaxy Morphology, Multi-wavelength, parallel, Self-Organizing Maps
Comparing Two Tablet-Based Visuomotor Tasks to Standard Laboratory Versions
The assessment of visuomotor function can provide important information about neurological status. Several visuomotor tasks exist for testing in the laboratory, although attempts to make these tests portable to allow quick and reliable assessment have been limited. We developed an assessment tool using two laboratory visuomotor tests as a tablet application: the double-step task, and an interception task. Performance was assessed by measuring the participants’ ability to reach toward unpredictably moving targets in each task. Response patterns were compared across equipment types to determine if participants were responding similarly to the moving targets in the standard laboratory and the tablet version of the tasks. On the double-step task, participants adjusted to the displaced target adequately in both the lab and tablet versions. On the interception task, participants intercepted non-accelerating targets, and performed worse on accelerating targets in both versions of the task. These findings suggest that the tablet version of these tasks assesses similar visuomotor processing as the respective laboratory version. Author Keywords: concussion assessment, double-step task, interception task, visuomotor processing, visuomotor system
Aeolian Impact Ripples in Sand Beds of Varied Texture
A wind tunnel study was conducted to investigate aeolian impact ripples in sand beds of varied texture from coarsely skewed to bimodal. Experimental data is lacking for aeolian megaripples, particularly in considering the influence of wind speed on ripple morphometrics. Additionally, the modelling community requires experimental data for model validation and calibration. Eighteen combinations of wind speed and proportion of coarse mode particles by mass were analysed for both morphometrics and optical indices of spatial segregation. Wind tunnel conditions emulated those found at aeolian megaripple field sites, specifically a unimodal wind regime and particle transport mode segregation. Remote sensing style image classification was applied to investigate the spatial segregation of the two differently coloured size populations. Ripple morphometrics show strong dependency on wind speed. Conversely, morphometric indices are inversely correlated to the proportion of the distribution that was comprised of coarse mode particles. Spatial segregation is highly correlated to wind speed in a positive manner and negatively correlated to the proportion of the distribution that was comprised of coarse mode particles. Results reveal that the degree of spatial segregation within an impact ripple bedform can be higher than previously reported in the literature. Author Keywords: Aeolian, Impact Ripples, Megaripple, Self-organization, Wind Tunnel
TESTING THE ROLE OF BIMODAL CELLS IN NEAR-HAND EFFECTS
We investigated whether hand-proximity effects arise from the recruitment of visual-tactile bimodal cells. In Experiment 1, we executed right-hand open-loop reaching movements to targets, presented either near or far from the resting left-hand, and after applying repetitive transcranial magnetic stimulation (rTMS) to suppress neuronal activity in the PMd and AIP, in Experiment 2. Results from Experiment 1, indicated that near-hand targets improved accuracy and reduced variability. In Experiment 2, suppressing PMd showed similar near-hand effects as above. In contrast, applying rTMS to AIP disrupted the representation of target location, indicating less accuracy and greater error. Near-hand proximity effects possibly arise from the recruitment of visual-tactile bimodal cells within the human AIP. Author Keywords: anterior intraparietal sulcus, peripersonal space, repetitive transcranial magnetic stimulation (rTMS), , rTMS, anterior intraparietal sulcus, AIP., visual-tactile bimodal neurons
Analyzing the Effectiveness of Social Movements Opposing Fossil Fuel Infrastructure
Blocking fossil fuel infrastructure projects like pipelines is increasingly being seen as a legitimate way for civil society groups to reduce global carbon emissions. This research project is an exploratory case study of the Trans Mountain pipeline in British Columbia and its opposition. My research question asks, ‘What has each tactic/strategy of opposition in the campaign to stop the Trans Mountain pipeline expansion accomplished, and how have they been effective? How can they be done more effectively?’ Through interviews and an autoethnography, my research explores the effectiveness of activists in this campaign. I analyze the results of my findings within social movement theory and other activist definitions of effectiveness from my literature review. The more significant findings from my research are that activists need to do a better job educating the public on the issue, need to direct more of their resources towards promoting a solution to the issue and make alliances with other movements and groups. This research project contributes to the literature on the effectiveness of oppositional strategies and tactics of pipeline resistance, as well as social movement theory. Author Keywords: British Columbia, pipeline, protest, strategy, tactic, Trans Mountain
Critical Analysis of the Adoption of Maize in Southern Ontario and its Spatial, Demographic, and Ecological Signatures
This thesis centers on analyzing the spatial, temporal, and ecological patterns associated with the introduction of maize horticulture into Southern Ontario - contextualized against social and demographic models of agricultural transition. Two separate analyses are undertaken: a regional analysis of the spread of maize across the Northeast using linear regression of radiocarbon data and a standard Wave of Advance model; and a local analysis of village locational trends in Southern Ontario using a landscape ecological framework, environmental data and known village sites. Through the integration of these two spatial and temporal scales of analysis, this research finds strong support for both migration and local development. A third model of competition and coalescence is presented to describe the patterning in the data. Author Keywords: Demographic Modeling, Environmental Modeling, Geostastical Analysis, Maize, Ontario Archaeology, Spread of Agriculture
Paleolandscape Reconstruction of Burleigh Bay, Ontario 12,600 cal BP to Present
This thesis presents a palaeotopographic reconstruction of the Burleigh Bay region of Stony Lake (Kawartha Lakes Region, Ontario) from 12,600 cal BP to present. The paleotopographic reconstructions are used to model paleoshoreline locations and archaeological site potential for the Late Paleoindian and early Archaic periods. Isostatic rebound following the end of the last glacial period has altered the topography in the region and water levels are now artificially managed by dams constructed in the 1830s. I completed a high-resolution bathymetric survey using a kayak equiped with a GPS coupled single-beam sonar. Utilizing GIS technology and isostatic rebound response surface models, I created paleotopographic reconstructions for 12,600 cal BP, 11,500 cal BP, 7,000 cal BP, 5,700 cal BP, and present. Results show that water levels in Burleigh Bay have been regressing over time until dam construction. Early site potential is centered in northern inland areas. Site potential following 7,000 cal BP is concentrated in northern areas flooded by the dam. Based on the reconstructions, surveys in lacustrine granite shield regions that follow the Ontario Standards and Guidelines for Consultant Archaeologists risk missing areas of high archaeological potential for early sites in these environments. Paleolandscape reconstructions would alleviate this issue by modeling paleoshoreline changes over time. Author Keywords: Canadian Shield, Early Archaic, Isostatic Rebound, Kawartha Lakes, Late Paleoindian, Paleolandscape
Civil Aviation and Scheduled Air Services in Colonial Botswana, 1935-1966
This thesis provides an in-depth and chronological study of the development of civil aviation in the Bechuanaland Protectorate (today’s Botswana), and the role played by the British Government in the development of this form of transport. The thesis argues that Her Majesty’s Government’s neglect and very little interest in its protectorate’s civil aviation represented a form of underdevelopment. The study also reveals the constant contradiction between the neglect of the imperial government and the constant lobbying on the part of colonial administration in the Protectorate for the establishment of an air service. To the colonial administrators, civil aviation represented a symbol of modernity and progress as well as more practical advantages such as mobility. The thesis finally concludes that the Bechuanaland Protectorate’s first airline was established due to growing nationalism both locally and on the continent, at large. The British Government facilitated the establishment of the airline as an attempt to appear benevolent to the protectorate on the eve of independence. Author Keywords:
Investigating the sources and fate of monomethylmercury and dimethylmercury in the Arctic marine boundary layer and waters
Monomethylmercury (MMHg), the most bioavailable form of mercury (Hg) and a potent neurotoxin, is present at elevated concentrations in Arctic marine mammals posing serious health threats to the local populations relying on marine food for their subsistence living. The sources of MMHg in the Arctic Ocean surface water and the role of dimethylmercury (DMHg) as a source of MMHg remain unclear. The objective of this research was to determine the sources and fate of methylated Hg species (MMHg and DMHg) in the marine ecosystem by investigating processes controlling the presence of methylated Hg species in the Arctic Ocean marine boundary layer (MBL) and surface waters. A method based on solid phase adsorption on Bond Elut ENV was developed and successfully used for unprecedented measurement of methylated Hg species in the MBL in Hudson Bay (HB) and the Canadian Arctic Archipelago (CAA). MMHg and DMHg concentrations averaged 2.9 ± 3.6 (mean ± SD) and 3.8 ± 3.1 pg m-3, respectively, and varied significantly among sampling sites. MMHg in the MBL is suspected to be the product of marine DMHg degradation in the atmosphere. MMHg summer (June to September) atmospheric wet deposition rates were estimated to be 188 ± 117.5 ng m-2 and 37 ± 21.7 ng m-2 for HB and CAA, respectively, sustaining MMHg concentrations available for bio-magnification in the pelagic food web. The production and loss of methylated Hg species in surface waters was assessed using enriched stable isotope tracers. MMHg production in surface water was observed from methylation of inorganic Hg (Hg(II)) and, for the first time, from DMHg demethylation with experimentally derived rate constants of 0.92 ± 0.82 x 10-3 d-1 and 0.04 ± 0.02 d-1 respectively. DMHg demethyation rate constant (0.98 ± 0.51 d-1) was higher than that of MMHg (0.35 ± 0.25 d-1). Furthermore, relationships with environmental parameters suggest that methylated Hg species transformations in surface water are mainly biologically driven. We propose that in addition to Hg(II) methylation, the main processes controlling MMHg production in the Arctic Ocean surface waters are DMHg demethylation and deposition of atmospheric MMHg. These results are valuable for a better understanding of the cycle of methylated Hg in the Arctic marine environment. Author Keywords: Arctic Ocean, Atmosphere, Demethylation, Dimethylmercury, Methylation, Monomethylmercury
Interactome study of the Giardia intestinalis nuclear localized cytochrome b5
Giardia intestinalis is a waterborne enteric parasite that lacks mitochondria and the capacity for heme biosynthesis. Despite this, Giardia encodes several heme proteins, including four cytochrome b5 isotypes (gCYTB5-I – IV) of unknown function. The aim of this thesis is to gain insight into the function of the Giardia cytochrome b5 isotype III (gCYTB5-III) that is found in the nucleus, as first reported by our laboratory using immunofluorescence microscopy experiments with an isotype-III specific antibody. Nuclear localization of isotype-III is supported by two of my experiments: i) immunoblot analysis of crude cytoplasmic and nuclear enriched fractions of Giardia trophozoites; ii) association of gCYTB5-III with the insoluble fraction of Giardia lysates crosslinked with formaldehyde is reversed by DNase I treatment. To gain an understanding of the possible roles of gCYTB5-III, I performed immunoprecipitation (IP) experiments on lysates from Giardia trophozoites to identify its protein partners. Mass spectroscopy analysis of the immunoprecipitate identified proteins localized to the nucleus (RNA polymerase, DNA topoisomerase, histones, and histone modifying enzymes). Intriguingly, over 40% of the known mitosomal proteome, which functions in iron-sulfur (Fe-S) cluster assembly was also associated with gCYTB5-III. One of these proteins, the flavoenzyme GiOR-1, has been shown to mediate electron transfer from NADPH to recombinant gCYTB5-III. These IP results provide evidence that GiOR-1 and gCYTB5-III interact in vivo, and furthermore, suggest that some proteins in the mitosome could interact with those in the nucleus. I also found that DNA stress, caused by low concentrations of formaldehyde (0.1 – 0.2%) resulted in the increased expression of gCYTB5-III. Collectively these findings suggest a role of gCYTB5-III in Giardia's response to DNA stress and perhaps the formation of Fe/S clusters. Author Keywords: cluster, cytochrome, heme, iron, mitosome, nuclear
Agro-Ecological Zoning (AEZ) of Southern Ontario and the Projected Shifts Caused by Climate Change in the Long-term Future
This thesis proposes an agro-ecological zoning (AEZ) methodology of southern Ontario for the characterization and mapping of agro-ecological zones during the historical term (1981-2010), and their shifts into the long-term (2041-2070) projected climate period. Agro-ecological zones are homogenous areas with a unique combination of climate, soil, and landscape features that are important for crop growth. Future climate variables were derived from Earth System Models (EMSs) using a high emission climate forcing scenario from the Intergovernmental Panel on Climate Change 5th Assessment Report. The spatiotemporal shifts in agro-ecological zones with projected climate change are analyzed using the changes to the length of growing period (LGP) and crop heat units (CHU), and their manifestation in agro-climatic zones (ACZ). There are significant increases to the LGP and CHU into the long-term future. Two historical ACZs exist in the long-term future, and have decreased in area and shifted northward from their historical locations. Author Keywords: Agro-climatic Zones, Agro-ecological Zones, Agro-ecological Zoning, Climate Change, Crop Heat Units, Length of Growing Period

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Format: 2024/02/21