Graduate Theses & Dissertations


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
Ligand Binding Properties of Giardia Flavohemoglobin
The parasitic protist Giardia intestinalis possesses flavohemoglobin (gFlHb), an enzyme that detoxifies nitric oxide to the less harmful nitrate, and is a potential target for antigiardial drugs that act as ligands to the iron of its heme cofactor. In this work, the binding constants KD of gFlHb, three active-site variants (Q54L, L58A, Y30F) and the E. coli flavohemoglobin (Hmp) towards cyanide, azide and several substituted imidazoles were measured by optical titration. Certain cases such as gFlHb and Hmp were studied further by isothermal titration calorimetry. Binding constants for cyanide and the imidazoles ranged from 2 to 100 M, with the highest affinities observed with for miconazole, a bulky substituted imidazole. Azide was a poor ligand, with binding constants between 0.48 and 26 mM. Among gFlHb and its mutants, L58A tended to have the highest ligand affinities, as mutation of the distal leucine to a less bulky distal alanine residue facilitates the access of the exogenous ligand to the heme iron. In contrast, the Q54L and Y30F variants had binding affinities that in most cases were similar to wild type, which suggests that the inability of their side chains to form hydrogen bonds to these ligands is not a significant factor in binding of imidazole ligands to the enzyme. Comparative results for Hmp and gFlHb ligand binding affinities revealed slight differences which might be explained by the presence of different residues in their active sites apart from their conserved residues. Author Keywords: Flavohemoglobin, Giardia intestinalis, Imidazole binding, Ligand binding, Nitrosative stress
Patterns of Vegetation Succession on Nickel-Copper Mine Tailings near Sudbury, Ontario
Natural establishment of vegetation on mine tailings is generally limited. Understanding the processes leading to vegetation germination and the survival mechanisms that vegetation species employ in these harsh environments is critical to future remediation efforts. As metalliferous mine tailings are generally nutrient-poor, high in harmful metals, and acidic, vegetation species require distinct mechanisms to germinate and survive in such harsh environments. In this study, edaphic and biotic factors linked to vegetation establishment and diversity were studied at two nickel-copper (Ni-Cu) tailings sites near Sudbury, Ontario. One site had experienced minimal treatment, and the second site was split into partial (hand-distribution of lime) and full (lime, fertilizer, seeding) treatment areas. Tailings were generally acidic, low in organic matter and “available” nutrients, and high in metals such as Al, Cu, Fe, and Ni, but these physical and chemical properties were extremely spatially variable. At both sites, vegetation was distributed in sparse patches, with the greatest diversity in treated areas. There was no clear link between metals and vegetation establishment/diversity at the sites. The primary limiting nutrients on the tailings were phosphorous (P) and potassium (K), and while there were areas of increased soil fertility at the sites, they were not clearly associated with increased vegetation diversity. Both traditional ecological succession and nucleation succession patterns were observed on the site, and the chief species associated with nucleation were primary colonizing trees such as B. papyrifera and P. tremuloides. The relationship between B. papyrifera nutrient retranslocation and tailings restoration was assessed and while B. papyrifera at the sites were deficient in P and K, the trees efficiently retranslocated both P and K during senescence. This research can provide insight into possibilities for future revegetation of similar tailings, enabling industry to make educated decisions when choosing where and how to revegetate, mimicking natural succession patterns. Author Keywords: Acid-mine drainage, Betula papyrifera, ecosystem health, metals, Sudbury, tailings
Investigation of Air Recirculation and Thermal Efficiency within a Climate Controlled Passage
Historically, entrances have been used for passage between two separate temperature environments, such as moving from inside to outside of a building. Energy loss through entrances is a cause for concern, as it has been known to increase energy consumption to replace the lost energy; and with the exchange of air masses and cold air entering the building, human discomfort may occur. In this research, thermal efficiency and air circulation within a Conventional Entrance (CE) and Climate Controlled Passage (CCP) are compared. A small scale model of the CE and CCP was constructed to examine forty-eight energy exchange conditions, emulating those found through an entrance between a temperature controlled lab and the model. Instruments such as a power meter, a flow explorer laser Doppler anemometer, and thermocouples were used to measure and compare the energy consumption, velocity vectors, and temperature energy within the entrance. Results indicate that the CCP did retain thermal energy compared to the CE. The CE developed sloped isotherm lines and air flow that enabled and maintained thermal exhaust. Conversely, the CCP developed horizontal isotherm lines and a two-layer density current to recirculate and retain thermal energy. The research demonstrates that it is possible to increase energy efficiency of entrances in many applications. Author Keywords: Air Recirculation, Building, Entrance, Oven, Thermal Energy Efficiency, Two-layer Density Current
Modelling Monthly Water Balance
Water balance models calculate water storage and movement within drainage basins, a primary concern for many hydrologists. A Thornthwaite water balance model (H2OBAAS) has shown poor accuracy in predicting low flows in the Petawawa River basin in Ontario, so lake storage and winter snow processes were investigated to improve the accuracy of the model. Lake storage coefficients, represented by the slopes of lake stage vs. lake runoff relationships, were estimated for 19 lakes in the Petawawa River basin and compared on a seasonal and inter-lake basis to determine the factors controlling lake runoff behaviour. Storage coefficients varied between seasons, with spring having the highest coefficients, summer and fall having equal magnitude, and winter having the lowest coefficients. Storage coefficients showed positive correlation with lake watershed area, and negative correlation with lake surface area during summer, fall, and winter. Lake storage was integrated into the H2OBAAS and improved model accuracy, especially in late summer, with large increases in LogNSE, a statistical measure sensitive to low flows. However, varying storage coefficients with respect to seasonal lake storage, watershed area, and surface area did not improve runoff predictions in the model. Modified precipitation partitioning and snowmelt methods using monthly minimum and maximum temperatures were incorporated into the H2OBAAS and compared to the original methods, which used only average temperatures. Methods using temperature extremes greatly improved simulations of winter runoff and snow water equivalent, with the precipitation partitioning threshold being the most important model parameter. This study provides methods for improving low flow accuracy in a monthly water balance model through the incorporation of simple snow processes and lake storages. Author Keywords: Lake Storage, Model Calibration, Monthly Water Balance, Petawawa River, Precipitation Partitioning, Snow Melt
Comparison of Dehydration Techniques for Acute Weight Management in Rowing
Mild sauna dehydration and fluid abstinence were investigated as weight loss strategies for lightweight rowers. Rowers (N=12) performed a power test, an incremental VO2max test, and a visuomotor battery: once euhydrated, once following sauna dehydration (SAU), and once following fluid abstinence and then sauna dehydration (FA). The percent body mass change (%BMC) achieved, %BMC attributable to sauna dehydration, and %BMC attributable to fluid abstinence were used within linear mixed effects models to predict hydration and performance variables. Sauna and overnight dehydration exerted indistinguishable effects on plasma osmolality, urine osmolality and thirst (p > .05). Fluid abstinence but not sauna dehydration was related to lower power production on the power test (b = 12.14W / 1%BMC, FA = 673.46 ± 79.50, SAU = 683.33 ± 72.08, p = .029), a lower total wattage produced on the incremental VO2max test (b = 4261.51W / 1%BMC, FA = 71029.58 ± 16256.56, SAU = 74001.50 ± 14936.56, p = .006), lower wattages at 2 mmol/L (b = 27.84W / 1%BMC, FA = 180.74 ± 40.27, SAU = 190.82 ± 50.79, p < .001) and 4 mmol/L (b = 20.45W / 1%BMC, FA = 221.90 ± 52.62, SAU = 238.89 ± 40.78, p = .002) blood lactate, and slower movement time on a visuomotor task (b = -38.06ms / 1%BMC, p = .004). Mild fluid abstinence but not sauna dehydration reduces rowing performance when two-hour rehydration is allowed. Author Keywords: crew, fluid, hydration, lightweight, sauna, weight
Shorebird Habitat Use and Foraging Ecology on Bulls Island, South Carolina During the Non-Breeding Season
Recent declines in North American shorebird populations could be linked to habitat loss on the non-breeding grounds. Sea-level rise and increased frequency of coastal storms are causing significant erosion of barrier islands, thereby threatening shorebirds who rely on shoreline habitats for foraging. I conducted shorebird surveys on Bulls Island, South Carolina in the winters of 2018 and 2019 and examined habitat selection and foraging behaviour in Dunlin (Calidris alpina), Sanderling (Calidris alba), Semipalmated Plovers (Charadrius semipalmatus), and Piping Plovers (Charadrius melodus). Area, tidal stage, and invertebrate prey availability were important determinants of shorebird abundance, behaviour, and distribution. My study highlights the importance of Bulls Island’s habitat heterogeneity to supporting a diverse community of non-breeding shorebirds. Considering both the high rate of erosion and the increased frequency of disturbance along the shoreline of the island, intertidal habitats should be monitored to predict negative effects of changes in habitat composition and area on non-breeding shorebirds. Author Keywords: foraging behaviour, habitat loss, habitat selection, invertebrate prey, non-breeding, shorebirds
Discriminating grey wolf (Canis lupus) predation events in a multi-prey system in central Saskatchewan
I investigated if spatio-temporal behaviour of grey wolves (Canis lupus) determined via GPS collar locations could be used to discriminate predation events generally, and among prey species, in Prince Albert National Park during winter, 2013-2017. I used characteristics of spatio-temporal GPS clusters to develop a predictive mixed-effect logistic regression model of which spatial clusters of locations were wolf kill sites. The model suffered a 60 % omission error when tested with reserved data due to the prevalence of deer kills with correspondingly low handling time. Next, I found a multivariate difference in the percentage of habitat classes used by wolves in the 2 hours preceding predation events of different prey species, suggesting that wolf habitat use reflects prey selection at a fine-scale. My results highlight the difficulty and future potential for remoting discriminating wolf predation events via GPS collar locations in multi-prey ecosystems. Author Keywords: Canis lupus, GPS clusters, GPS collars, grey wolf, habitat use, predation
multi-faceted approach to evaluating the detection probability of an elusive snake (Sistrurus catenatus)
Many rare and elusive species have low detection probabilities, thereby imposing unique challenges to monitoring and conservation. Here, we assess the detection probability of the Eastern Massasauga (Sistrurus catenatus) in contrast to a more common and conspicuous species, the Eastern Gartersnake (Thamnophis sirtalis). We found that patterns of detection probability differed between species, wherein S. catenatus was detected less often and under a more specific set of sampling conditions. Correspondingly, detection trials with S. catenatus found a high non-detection rate, while detection trials with artificial models suggest that regional differences in detection probability are driven by variation in population density and habitat use. Our results suggest that current monitoring efforts are not sufficient, and that S. catenatus is frequently undetected. Accordingly, we highlight the importance of species-specific monitoring protocols when monitoring rare and elusive species, and recommend a multi-faceted approach that estimates detection probability and identifies species-specific challenges to monitoring. Author Keywords: detection probability, elusive species, monitoring programs, non-detection, S. catenatus, snakes
Effects of Local, Landscape, and Temporal Variables on Bobolink Nest Survival in Southern Ontario
Populations of grassland birds, including the Bobolink (Dolichonyx oryzivorus), are experiencing steep declines due to losses of breeding habitat, land use changes, and agricultural practices. Understanding the variables affecting reproductive success can aid conservation of grassland species. I investigated 1) whether artificial nest experiments accurately estimate the impacts of cattle on the daily survival rate of Bobolink nests and 2) which local, landscape, and temporal variables affect daily survival rate of Bobolink nests in Southern Ontario. I replicated an artificial nest experiment performed in 2012 and 2015 to compare the daily survival rate of artificial and natural nests at multiple stocking rates (number of cattle × days × ha-1). I also monitored Bobolink nests and modeled daily survival rate using local variables (e.g., stocking rate, field use, patch area), landscape variables (e.g., percent forest within 2, 5, and 10 km), and temporal variables (e.g., year, date of season). Results indicate that artificial nest experiments using clay shooting targets overestimated the impacts of stocking rate on the daily survival rate of Bobolink nests. With natural nests, region (confounded by year and field use), stocking rate, and date of season were the strongest predictors of daily survival rate; with stocking rate and date of season both having a negative effect. Management should focus on conserving pastures with low stocking rates (< 40 cattle × days × ha-1), late-cut hayfields, fallow fields, and other grasslands to protect breeding grounds for the Bobolink and other declining grassland bird species. Author Keywords: Bobolink, Daily survival rate, landscape variables, local variables, Nest survival, temporal variables
Impaired contextual fear discrimination learning after long-term amygdala kindling
Cognitive impairments, such as memory loss, are a frequent and devastating co-morbidity associated with epilepsy. The neurobiological mechanisms through which recurrent seizures induce cognitive impairments are not well understood. New neurons born after seizures develop abnormal morphological and functional characteristics that promote network hyperexcitability and hippocampal dysfunction. Previously, we found that kindling dramatically increases the rate of neurogenesis at early stages of seizure development, followed by a long-term suppression at later stages. These changes in the rate of cell proliferation coincides with aberrant modifications in the migration, excitability, and functional integration of these new neurons. It has been suggested that the long-term consequences of seizure-induced neurogenesis contributes to the development of cognitive impairment seen in chronic epilepsy. However, direct experimental evidence has been limited. The present series of experiments sough to determine if blocking aberrant seizure-induced neurogenesis can reduce cognitive deficits associated with chronic epilepsy. Our findings suggest that chronic seizures impair the ability of rats to differentiate between similar contexts. In addition, blocking aberrant seizure-induced neurogenesis through treatment with the cytotoxic agent temozolomide was capable of preventing some of the deficits in context discrimination learning when neurogenesis levels were reduced to non-epileptic control levels. This research provides further support of targeting aberrant neurogenesis as a novel treatment to restore cognitive functioning in individuals living with epilepsy. Author Keywords: Amygdala kindling, Dentate gyrus, Hippocampus, Neurogenesis, Pattern separation, Seizures
Is semantics activated automatically? Evidence from the PRP paradigm
Three experiments examined whether semantics is activated automatically by testing whether Arabic digits (e.g., 4), number words (e.g., four), and non-number words (e.g., rat) activate semantics in the absence of central attention within the Psychological Refractory Period (PRP) paradigm. In all three experiments, subjects performed colour discriminations as Task 1. In Task 2, subjects performed magnitude comparisons on digits (Experiment 1) and number words (Experiment 2) and size comparisons on animal words (Experiment 3). Task overlap was controlled by varying stimulus onset asynchrony (SOA). A distance effect arose in Task 2 and yielded underadditive effects with decreasing SOA for both digits and number words, consistent with these notations activating semantics in the absence of central attention, or automatically. A distance effect also arose for animal words, but it was additive with SOA, inconsistent with non-number words activating semantics automatically. Author Keywords: Automaticity, Central attention, Dual-task, Numerical cognition, Semantics, Word recognition


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