Graduate Theses & Dissertations

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Effects of biodiversity and lake environment on the decomposition rates of aquatic macrophytes in the Kawartha Lakes, Ontario
Decomposition of aquatic macrophytes has an important role in defining lake carbon (C) storage and nutrient dynamics. To test how diversity impacts decomposition dynamics and site-quality effects, I first examined whether the decomposition rate of aquatic macrophytes varies with species richness. Generally, I found neutral effects of mixing, with initial stoichiometry of component species driving decomposition rates. Additionally, external lake conditions can also influence decomposition dynamics. Therefore, I assessed how the decomposition rate of a submersed macrophyte varies across a nutrient gradient in nine lakes. I found decomposition rates varied among lakes. Across all lakes, I found Myriophyllum decomposition rates and changes in stoichiometry to be related to both nutrients and water chemistry. During the incubation changes in detrital stoichiometry were related to lake P and decomposition rates. Aquatic plant community composition and stoichiometry could alter decomposition dynamics in moderately nutrient enriched lakes. Author Keywords: Aquatic Plants, Decomposition, Diversity, Littoral, Macrophytes, Nutrients
Evaluation of silver nanoparticles (AgNPs) and anti-GD2-AgNP antibody-drug conjugates as novel neuroblastoma therapies
Neuroblastoma (NB) has one of the highest mortality rates in pediatric oncology due to relapsed and refractory disease. Current aggressive multi-modal treatments are inhibited by dose-limiting toxicities and are associated with late-effects and secondary malignancies, emphasizing the necessity for novel therapeutics. Uniquely, most NB cells highly express disialoganglioside (GD2) a cell surface glycolipid that can provide a target for tumour-specific delivery. This study demonstrates a comprehensive evaluation of silver nanoparticles (AgNPs) and the first preliminary evaluation of anti-GD2-AgNP antibody-drug conjugates (ADCs) against NB in vitro. This present study validates the potential for AgNPs as an anti-cancer agent against NB as AgNPs demonstrated preferential toxicity towards NB cells through metabolic inhibition and indicative morphological alterations, while a less tumorigenic cell line demonstrated resistance to AgNP treatment. Therefore, this work identified an AgNP cell-type-dependent cytotoxicity effect. Low conjugation efficiency of the anti-GD2 monoclonal antibody, 14.G2a, to NHS-activated AgNPs failed to exert greater toxicity than the AgNPs alone. Collectively, this thesis provides novel information regarding the anti-cancer effects of AgNPs against NB with recommendations for anti-GD2-AgNP ADCs. Author Keywords: ADC, Chemotherapy, GD2, Neuroblastoma, Silver nanoparticles
Archaeology, Engagement and Local Communities
This research is an ethnographic investigation into the relationships between the Stélida Naxos Archaeological Project and the local population of Vivlos, the region where the team takes their seasonal residence during their annual archaeological field season. Fieldwork in Vivlos revealed the local peoples’ interest in archaeology, local legends, and Greek history. The people’s cultural identity facilitated a sense of communal pride with hosting the archaeologists for their field season. The archaeologists’ ethical considerations and their friendliness towards the locals during their time in Vivlos followed practices affiliated with public archaeology, laying the groundwork for maintaining positive working relations between the two groups. Author Keywords: Archaeology, Engagement, Local Communities, Public Outreach
Older Voluntarism and Rural Community Sustainability
With regards to building knowledge about rural aging, there is a gap in understanding of the diversity of older rural people’s experiences and the interaction between older rural people and the development trajectories of aging rural communities. One way to examine these experiences and interactions is through voluntarism; the activities of volunteers and voluntary organizations, which are pivotal for supporting aging in place in often-underserviced rural communities. To address this gap, this thesis features a community-based case study with a volunteer-based rural library in Ontario, Canada and was aimed at understanding the experiences of older library volunteers, examining the challenges of a rural library volunteer program and exploring how they contribute to rural community sustainability. Through surveys (n=87), interviews (n=48) and focus groups (n=6) with library volunteers, staff, board members and community leaders the findings demonstrate how older voluntarism is felt through the lived experiences of individual volunteers, poses interpersonal, operational and structural challenges, and can potentially contribute to the sustainability of rural communities. The thesis contributes to our understanding of the rural, older voluntarism and provides recommendations for ways to sustain library volunteer programs. Author Keywords:
Assessing Molecular and Ecological Differentiation in Wild Carnivores
Wild populations are notoriously difficult to study due to confounding stochastic variables. This thesis tackles two components of investigating wild populations. The first examines the use of niche modeling to quantify macro-scale predator-prey relationships in canid populations across eastern North America, while the second examines range-wide molecular structure in Canada lynx. The goal of the first chapter is to quantify niche characteristics in a Canis hybrid zone of C. lupus, C. lycaon, and C. latrans to better understand the ecological differentiation of these species, and to assess the impacts of incorporating biotic interactions into species distribution models. The goal of the second chapter is to determine if DNA methylation, an epigenetic marker that modifies the structure of DNA, can be used to differentiate populations, and might be a signature of local adaptation. Our results indicated that canids across the hybrid zone in eastern North America exhibit low levels of genetic and ecological differentiation, and that the importance of biotic interactions are largely lost at large spatial scales. We also identified cryptic structure in methylation patterns in Canada lynx populations, which suggest signatures of local adaptation, and indicate the utility of DNA methylation as a marker for investigating adaptive divergence. Author Keywords: Ecological Epigenetics, Ecological Genetics, SDM
An Application of Virgilio Enriquez's Indigenization Method on Filipino-Canadian Discourse
In Disturbing Invisibility (Coloma, McElhinny, Tungohan, Catungal, Davidson, 2012), the most comprehensive book on Filipino-Canadian studies to date, issues were identified in the afterword as to how Filipino-Canadian studies relates to indigenous identity. This thesis attempts to address this issue by applying Enriquez’s (1992) Indigenization Method onto Filipino-Canadian discourse. It attempts to do this by: exploring the colonial context and history in the Philippines and its effect on the formation of a Filipino indigenous identity; exploring Filipino indigenous thought as described by Enriquez (1992) in his seminal book From Colonial to Liberation Psychology; understanding Filipinos in Canada with the inclusion of literature from Filipino-American studies and the Filipino Indigenization movement; and how orienting Filipino-Canadian discourse with the indigenous concepts brought forward by Enriquez might look like, with emphasis on how Filipino-Canadian discourse could interact with Indigenous issues relating to Indigenous People in Canada today. It becomes clear that the Filipino Indigenization movement has reached grassroots Filipino organizations in Canada, and that uncritically ignoring their own Filipino indigenous roots would be denying themselves the unique cultural gifts that those roots provide. As being both Filipino and Canadian, Filipino-Canadians who seek to reclaim their indigenous roots would find that the indigenous concept of kapwa (“the self in the other”) would encourage an examination of issues pertaining to Indigenous People in Canada as commonalities exist in their experiences with colonization. Author Keywords: Canada, discourse, Filipino-Canadians, indigenization, indigenous, Philippines
Role of Policy in Arctic Food (In)Security
Hunger is a significant concern in Canada, and even more so in the North, with 52% of Inuit adults in Arctic regions experiencing some level of food insecurity in 2012. Policy deficiencies are argued to, at the least, be partly responsible for this issue. This qualitative exploratory project aimed to answer the question: What is the role of food-related policy(ies) in household food security? A review and analysis of policy documents and academic literature at three jurisdictional levels, using the case of food insecurity in Nunavik, Québec, was conducted. The study identified 281 policies facilitating and 139 policies acting as barriers to food security. The highest proportion (27%) of facilitators related to economic accessibility of food and the highest proportion of barriers (93%) related to political accessibility of food. Only one previously identified factor influencing household food security in the region had a corresponding policy barrier associated with it. The study suggests that what is considered ‘food policy’ differs significantly between jurisdictions. Many of the same policies that act to facilitate some aspects of food security act as barriers to others. Policy barriers tend to be difficult to identify by their very nature. As a result, policy plays a complicated role in Nunavik food security status, representing a positive influence in some regards and a negative one in others. Author Keywords: Arctic, Food, Food security, Inuit, Nunavik, Policy
Detectability and its role in understanding upland sandpiper (Bartramia longicauda) occurence in the fragmented landscape of southern Ontario
Upland Sandpipers (Bartramia longicauda), like many grassland birds, are undergoing population decline in parts of their range. Habitat fragmentation and change have been hypothesized as potential causes of decline. I used citizen-science occurrence data from Wildlife Preservation Canada’s Adopt-A-Shrike Loggerhead Shrike (Lanius ludovicianus) program in conjunction with validation surveys, using similar point-count methods, to examine detectability and determine if landscape level habitat features could predict occupancy of Upland Sandpipers in Southern Ontario. In a single season detectability study, I used Wildlife Preservation Canada’s survey protocol to determine detectability in sites that were known to be occupied. Detectability was low, with six surveys necessary to ensure detection using a duration of at least 18 minutes early in the breeding season. The proportion of open habitat did not affect detection on the landscape. Using a larger spatial and temporal scale, with five years of citizen-science data, I showed that Annual Crop Inventory data could not effectively predict Upland Sandpiper occupancy. Model uncertainty could be attributed to survey protocol and life history traits of the Upland Sandpiper, suggesting that appropriate survey methods be derived a priori for maximizing the potential of citizen-science data for robust analyses. Author Keywords: Bartramia longicauda, citizen-science, detection, landscape, occupancy, Ontario
Effect Assessment of Binary Metal Mixtures of Ni, Cu, Zn, and Cd to Daphnia magna
Mixtures of metals occur in surface waters, toxicity of which has drawn world-wide attention due to their crucial role in both ecotoxicology and regulations. The present research was undertaken to study the acute toxicity of binary mixtures of Ni, Cu, Zn, and Cd to the freshwater organism, Daphnia magna. The experimental approach included single and binary metal toxicity tests based on the 48h acute toxicity bioassay of Environment Canada. The acute toxicity of single metals followed the order of Cd > Cu > Zn > Ni. Based on the calculated 48h EC50 value of single metals, a toxic unit (TU) approach was used to combine two metals in a binary mixture, in which 1TU was equal to the 48h EC50 value of a metal in single exposure. The toxicity of binary metal mixtures to D. magna followed the order of Cu-Cd > Cu-Zn > Zn-Cd > Cu-Ni > Zn-Ni > Cd-Ni, which demonstrated three types of toxicity (i.e., less than additive, additive, and greater additive). Predictions from additivity models (including concentration addition (CA) and independent action (IA) models), a generalized linear model (GLM), and a biotic-ligand-like model (BLM-like) were compared to the bioassay results. The CA and the RA models also predicted three types of toxicity of the binary metal mixtures (i.e., less than additive, additive, and greater than additive). However, the CA model mostly overestimated the toxicity of binary mixtures. Predictions from the GLM supported the inclusion of the interaction between two metals in a mixture to predict the toxicity of binary metal mixtures. The binary metal toxicity was also predicted using a BLM-like model based on the calculated concentrations of free ionic forms of the metals, affinity constants, and toxic potency of each metal. In this model, it was hypothesized that the toxicity of metal mixture is the result of competition of metals with Ca2+ at biotic ligands, which can lead to whole-body deficiency of Ca2+ in D. magna. The BLM-like model provided the toxic potency of single metals with the following order, Cu > Cd > Zn > Ni. Although the prediction of the BLM-like model was not in good agreement with the observed toxicity of binary metal mixtures, an overestimation of risk of mixture toxicity was obtained using this model, which could be promising for use in environmental risk assessment. Author Keywords: biotic ligand model, concentration addition, Daphnia magna, independent action, metal toxicity, modeling
spatial and temporal distribution of tabanid (Chrysops, Hybomitra and Tabanus) species in the Nakina district of northwestern Ontario
This thesis focused on expanding knowledge of Hybomitra, Chrysops and Tabanus (Diptera: Tabanidae) distributions north of Lake Nipigon, Ontario, in a managed boreal forest. As land use and climate changes accelerate, there is increased pressure to increase knowledge from which to monitor changes. In 2011 and 2012, 8928 individuals representing, 44 species were captured using sweep netting. Major northward range extensions were observed for Chrysops shermani, C. aberrans and Tabanus fairchildi. Smaller range extensions and in-fills were observed for another 15 species. 23 species had exntensions to their previously known seasonal range. C. carbonarius was the only species that showed an extension to both sides of its season. In general, harvested stands had 50% more individuals and 30% greater species richness than younger stands. A possible link between stand age and interspecific competition was identified. Information has been provided to build baseline of species richness, relative abundance and distribution of Tabanid flies. Author Keywords: diptera, distribution, natural history, northern Ontario, species range, tabanid
Role of Dielectric Screening in SrTiO3-Based Interfaces
We build a theoretical model for exploring the electronic properties of the two-dimensional (2D) electron gas that forms at the interface between insulating SrTiO3 (STO) and a number of perovskite materials including LaTiO3, LaAlO3, and GdTiO3. The model treats conduction electrons within a tight-binding approximation, and the dielectric polarization via a Landau-Devonshire free energy that incorporates STO's strongly nonlinear, nonlocal, field-, and temperature-dependent dielectric response. We consider three models for the dielectric polarization at the interface: an ideal-interface model in which the interface has the same permittivity as the bulk, a dielectric dead-layer model in which the interface has permittivity lower that the bulk, and an interfacial-strain model in which the strain effects are included. The ideal-interface model band structure comprises a mix of quantum 2D states that are tightly bound to the interface, and quasi-three-dimensional (3D) states that extend hundreds of unit cells into the STO substrate. We find that there is a substantial shift of electrons away from the interface into the 3D tails as temperature is lowered from 300 K to 10 K. We speculate that the quasi-3D tails form the low- density high-mobility component of the interfacial electron gas that is widely inferred from magnetoresistance measurements. Multiple experiments have observed a sharp Lifshitz transition in the band structure of STO interfaces as a function of applied gate voltage. To understand this transition, we first propose a dielectric dead-layer model. It successfully predicts the Lifshitz transition at a critical charge density close to the measured one, but does not give a complete description for the transition. Second, we use an interfacial-strain model in which we consider the electrostrictive and flexoelectric coupling between the strain and polarization. This coupling generates a thin polarized layer whose direction reverses at a critical density. The transition occurs concomitantly with the polarization reversal. In addition, we find that the model captures the two main features of the transition: the transition from one occupied band to multiple occupied bands, and the abrupt change in the slope of lowest energy band with doping. Author Keywords:
Pervert’s New Statesman
Justice Weekly was a tabloid published in Toronto from 1946 to 1972. The popular narrative is that it was an unremarkable, obscure, and pornographic paper which was co-opted by gay and homophile voices in the 1950s. But why did a magazine best remembered, as Mordecai Richler put it, as “the pervert’s new statesman” publish this material? This thesis argues that Justice Weekly really was primarily about Justice, rather than titillation. The paper explored justice through topics such as juvenile delinquency and spanking, which allowed sexualized material to appear, as well as conversations surrounding gay men, race, criminality, and punishment. While the paper outed gay men and often argued for harsher prison conditions, it also published material from Canada’s earliest gay activists and prisoner presses. Justice Weekly’s focus on equitable justice allowed both sex and advocacy to emerge from its content. Author Keywords: Delinquency, Homosexuality, Jim Egan, Pornography, Pulp, Tabloid

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Format: 2021/03/09