Graduate Theses & Dissertations

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Frequency-time and polarization considerations in spectral-focusing-based CARS microscopy
Spectral-focusing-based coherent anti-Stokes Raman scattering (SF-CARS) microscopy is a powerful imaging technique that involves temporally and spectrally stretching ultrashort laser pulses and controlling their frequency-time characteristics. However, a broader and more detailed understanding of the frequency-time characteristics of the laser pulses and signals involved, how they are related, and how they influence important aspects such as the spectral resolution is needed to understand the full potential of SF-CARS systems. In this work, I elucidate these relationships and discuss how they can be exploited to optimize SF-CARS microscopy setups. I present a theoretical analysis of the relationships between the spectral resolution, the degree of chirp-matching, and pulse bandwidth in SF-CARS. I find that, despite allowing better ultimate spectral resolution when chirp-matching is attained, the use of the broadest bandwidth pulses can significantly worsen the spectral resolution if the pulses are not chirp-matched. I demonstrate that the bandwidth of the detected anti-Stokes signal is minimized when the pump is twice as chirped as the Stokes, meaning that (perhaps counter-intuitively) a narrow anti-Stokes bandwidth does not imply good spectral resolution. I present approximate expressions that relate the bandwidths of the pump, Stokes, and anti-Stokes pulses to the degree of chirp-matching and outline how these could be used to estimate the amount of glass needed to attain chirp-matching. I develop a spectral-focusing-based polarization-resolved (SFP-CARS) setup, by modifying our existing system, to explore the merits of integrating polarization-dependent detection as an add-on to existing SF-CARS setups. By using the system to study polarization-dependent features in the CARS spectrum of benzonitrile, I assess its capabilities and demonstrate its ability to accurately determine Raman depolarization ratios. Ultimately, the detected anti-Stokes signals are more elliptically polarized than desired, hindering a complete suppression of the non-resonant background. Nevertheless, I find that the SFP-CARS setup is a useful tool for studying polarization-dependent features in the CARS spectra of various samples and is worthy of further investigation. This work clarifies several technical aspects of SF-CARS microscopy and provides researchers with valuable information to consider when working with SF-CARS microscopy systems. Author Keywords: coherent anti-Stokes Raman scattering, nonlinear microscopy, polarization, spectral focusing, spectroscopy
Experiencing buhts’an qu’inal from sHachel jwohc’ a’tel through sna'el ya'beyel stuc te bin ay ma'yuc
This thesis shows and emphasizes the importance of Indigenous Knowledge (IK) in informing collaborative efforts that promote sustainable economic development in Indigenous communities. It tells the story of a participative research study undertaken with six Tseltal communities located in the Region Selva of Chiapas, Mexico, in the context of the Covid19 pandemic of 2020 and early 2021. In this study, the research participants reflect on their endeavours pursuing projects focused on the economic self-sufficiency of their communities. Their initiatives, which are deeply grounded in Tseltal practices while accompanied by the local non-profit organization IXIM AC, focus on developing economically self-sustaining enterprises in self-organized groups led by local Indigenous women. The findings offer a deep immersion into two aspects that emerge from Tseltal knowledge: The Nucleus of Tseltal community wellbeing and the Four Elements of Buhts’an qu’inal (Tseltal community wellbeing). The study’s results show that these two IK grounded aspects guide the participants’ endeavours in developing sHachel jwohc’ a’tel (Tseltal initiatives of entrepreneurship) while also enabling opportunities for gender transformative collaborative work and sustained engagement in local initiatives of sna'el ya'beyel stuc te bin ay ma'yuc (Tseltal economic development oriented to community wellbeing). Author Keywords: Community Wellbeing, Indigenous Entrepreneurship, Indigenous Knowledges, Indigenous Women, Participative Action Research, Sustainable Development
Archaeology and Reconciliation in the Williams Treaties Territory
This thesis examines the history of Indigenous inclusion in the discipline of archaeology and how archaeologists can provide reconciliation when working with Indigenous peoples in their territory. This thesis focuses on the territory of the Williams Treaties with a particular focus on the location of Nogojiwanong (Peterborough). My data consists of in-depth interviews from ten informants and studying three case studies that happened in the area. I take my informants’ suggestions and apply them to my case studies, to show practical examples of how we can provide reconciliation in the field of archaeology. Author Keywords: Decolonization , Heritage Management , Indigenous, Reconciliation
Time Series Algorithms in Machine Learning - A Graph Approach to Multivariate Forecasting
Forecasting future values of time series has long been a field with many and varied applications, from climate and weather forecasting to stock prediction and economic planning to the control of industrial processes. Many of these problems involve not only a single time series but many simultaneous series which may influence each other. This thesis provides methods based on machine learning of handling such problems. We first consider single time series with both single and multiple features. We review the algorithms and unique challenges involved in applying machine learning to time series. Many machine learning algorithms when used for regression are designed to produce a single output value for each timestamp of interest with no measure of confidence; however, evaluating the uncertainty of the predictions is an important component for practical forecasting. We therefore discuss methods of constructing uncertainty estimates in the form of prediction intervals for each prediction. Stability over long time horizons is also a concern for these algorithms as recursion is a common method used to generate predictions over long time intervals. To address this, we present methods of maintaining stability in the forecast even over large time horizons. These methods are applied to an electricity forecasting problem where we demonstrate the effectiveness for support vector machines, neural networks and gradient boosted trees. We next consider spatiotemporal problems, which consist of multiple interlinked time series, each of which may contain multiple features. We represent these problems using graphs, allowing us to learn relationships using graph neural networks. Existing methods of doing this generally make use of separate time and spatial (graph) layers, or simply replace operations in temporal layers with graph operations. We show that these approaches have difficulty learning relationships that contain time lags of several time steps. To address this, we propose a new layer inspired by the long-short term memory (LSTM) recurrent neural network which adds a distinct memory state dedicated to learning graph relationships while keeping the original memory state. This allows the model to consider temporally distant events at other nodes without affecting its ability to model long-term relationships at a single node. We show that this model is capable of learning the long-term patterns that existing models struggle with. We then apply this model to a number of real-world bike-share and traffic datasets where we observe improved performance when compared to other models with similar numbers of parameters. Author Keywords: forecasting, graph neural network, LSTM, machine learning, neural network, time series
Assessing the Cost of Reproduction between Male and Female Sex Functions in Hermaphroditic Plants
The cost of reproduction refers to the use of resources for the production of offspring that decreases the availability of resources for future reproductive events and other biological processes. Models of sex-allocation provide insights into optimal patterns of resource investment in male and female sex functions and have been extended to include other components of the life history, enabling assessment of the costs of reproduction. These models have shown that, in general, costs of reproduction through female function should usually exceed costs through male function. However, those previous models only considered allocations from a single pool of shared resources. Recent studies have indicated that the type of resource currency can differ for female and male sex functions, and that this might affect costs of reproduction via effects on other components of the life history. Using multiple invasibility analysis, this study examined resource allocation to male and female sex functions, while simultaneously considering allocations to survival and growth. Allocation patterns were modelled using both shared and separate resource pools. Under shared resources, allocation patterns to male and female sex function followed the results of earlier models. When resource pools were separate, however, allocations to male function often exceeded allocations to female function, even if fitness gains increased less strongly with investment in male function than with investment in female function. These results demonstrate that the costs of reproduction are affected by (1) the types of resources needed for reproduction via female or male function and (2) via trade-offs with other components of the life history. Future studies of the costs of reproduction should examine whether allocations to reproduction via female versus male function usually entail the use of different types of resources. Author Keywords: Cost of Reproduction, Gain Curve, Life History, Resource Allocation Patterns, Resource Currencies
History and Legacy of the “Orillia Asylum for Idiots
The “Orillia Asylum for Idiots” (1861 - 2009), Canada’s oldest and largest facility for the care and protection of children and adults with disabilities, was once praised as a beacon of humanitarian progress and described as a “community within a community.” Yet, survivors who lived in the facility during the post Second World War period, a time described as the “golden age of children’s rights,” tell harrowing stories of abuse and neglect. Despite the nation’s promise to “put children first” and protect the universal rights of “Canada’s children,” children incarcerated within the Orillia Asylum were subjected to systemic neglect and cultural discrimination, daily humiliation and dehumanization, and physical, sexual, and emotional abuse. Far from being a place for child protection and care, this dissertation finds that the Orillia Asylum was a site of a multi-faceted and all-encompassing violence, a reality that stands in complete contrast to the grand narrative through which the facility has historically been understood. This dissertation considers how such violence against children could occur for so long in a facility maintained by the state, a state invested in protecting children. It finds that children who were admitted to the Orillia Asylum were not considered to be “Canada’s children” at all by virtue of being labelled as “mentally deficient,” “feeble-minded,” “not-quite-human,” and “not-quite-children.” Author Keywords: childhood, disability, Huronia Regional Centre, institutional child abuse, institutional violence, institutionalization
Shoreline Stewardship
This thesis aimed to determine what factors influence individual- and community-level shoreline stewardship attitudes and behaviours. Shoreline stewardship is part of the broader literature of environmental stewardship and place-based conservation. The needs and barriers limiting stewardship action were examined, as were the opportunities for increased impact. The Love Your Lake (LYL) program served as a case study into the impact of ENGO programming on shoreline stewardship among shoreline property owners in Ontario. This was investigated using a program workshop, interviews and focus groups with past program participants, and existing participant survey data. Community-Based Social Marketing principles were used to further examine the opportunities for increased impact on stewardship behaviour. The study found that the LYL program was effective in starting or continuing a conversation in communities around shoreline health. Some of the remaining needs and/or barriers included limited time at the cottage; limited knowledge of how to fix existing shoreline issues; low stock of local native plants and environmentally minded landscapers; ineffective messaging; a lack of interest, enthusiasm or concern; and weak environmental policies and governance of shorelines. Some participants also listed cost as a barrier, while others felt it had been well addressed already. Most participants thought that education could be a barrier but that it had been well addressed locally through LYL or other programming. Some key motivators and opportunities to increase shoreline stewardship included community building, increased lake association capacity, improved communication and marketing strategies, and persistence. Author Keywords: Community-Based Social Marketing, Environmental Stewardship, Lake Health, Place-Based Conservation, Pro-Environmental Behaviour, Shoreline Stewardship
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
Extraction and Characterization of Hyaluronic Acid and Collagen from Eggshell Membrane Waste
Connecting academia to industry is one important way to advance towards meeting the United Nations (UN) Sustainability Goals (SDGs).1 Sustainability can be applied to all industrial sectors with the SDGs being implemented by 2030.2 This research contributes to the SDGs by investigating a way to remediate an industrial waste stream in the egg-breaking industry. If adopted, this would reduce the amount of eggshell membrane (ESM) waste placed in landfill where it does not decompose properly. The work described in this thesis specifically targets extraction of collagen and hyaluronic acid (HA), two components of the ESM that are of commercial value in the cosmetic, pharmaceutical, and biomedical industries3,4 . Deliverables from this research include economically viable extraction methods, developed based on green chemistry approaches, that can be transferred from lab bench to industrial scale. The extraction development process was guided by the 12 Principles of Green Chemistry5,6,7 and the 12 Principles of Green Engineering.8 HA was most successfully extracted using a sodium acetate solution on ground ESM. Filtrate was collected, exhaustively dialyzed and lyophilized. High molecular weight HA was recovered. Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy and proton nuclear magnetic resonance (NMR) spectroscopy compared extracted material to reference HA identifying successful extraction. Collagen was extracted using acetic acid or pepsin enzyme digestion. Hydrophilic interaction liquid chromatography (HILIC) coupled with mass spectrometry (MS) compared amino acid composition of extracted materials to reference collagen material. FTIR-ATR spectra also supported successful extraction of collagen. This work identifies that HA and collagen can be conveniently extracted from ESM using an economical approach that can be implemented into egg-breaking facilities. This work highlights the benefits of connecting academia to industry to advance green chemical approaches while implementing sustainable practices into existing industry. Author Keywords: collagen, eggshell membrane waste, extraction, green chemistry, hyaluronic acid, sustainability
Finding Cowboy Joe
Canadian authored diverse LGBTQ2S children's picture books can help counter socialized aspects of heteronormativity and other forms of oppression. This thesis outlines the challenging process for identifying and locating Canadian authored diverse LGBTQ2S children's picture books, with suggestions provided for mitigating this process. Twenty-two books (list and summaries included) are collected and then analysed through three different lenses: Sipe’s Semiotically Framed Theory of Text-pictured Relationships; intersectionality; and Canadian Studies. Findings include: the significance of a micro press in offering representation for queer intersectionality, the shift from the portrayal of discrimination against queer parents to an attention to the policing of children’s gender identity and expression, and the embrace of the child on their own terms. In addition, a Canadian queer children’s book has been created by the researcher, developed through the process of writing of this thesis. Author Keywords: Canadian authors, Canadian identity, children’s picture books, countering heteronormativity, ethnic diversity, LGBTQ2S
(Re)encountering black bears
This thesis explores the perceptions of human-bear interactions in Ontario, suggesting that they have been shaped by narratives that have roots in colonial perceptions of nonhuman animals. Further, I seek to consider how these interactions could unfold differently if we rethought our relationships and responsibilities to these beings, in particular through an embrace of Indigenous-led conservation informed by ideas of animal welfare. The methods used for this research were first empirical, through qualitative data collection via interviews. Second, it was interpretive, through the observation of bear experiences and through the analysis of circulated and conceptual themes of bear information found in media articles. What emerged was an understanding that the mitigation efforts which are used when human-bear interactions occur are deeply influenced by political, social, and cultural factors that cannot be removed from these matters, asserting that a reconceptualization of current conservation frameworks needs to be considered. Author Keywords: Compassionate conservation, Human-bear interactions, Human-wildlife relations, Indigenous conservation, Narrative inquiry, Wildlife conservation
Adoption of a Finite Element Model of Material Deformation Relevant to Studying Corneal Biomechanics
The human cornea is required to exhibit specific material properties to maintain its regular shape under typical intraocular pressures which then allow for its correct optical functionality. In this thesis, the basis of continuum solid mechanics and the finite element method are introduced. We use finite element modelling to simulate the extension of an effective-1d, linear-elastic bar, a cornea-like body governed by Poisson’s equation, and the deformation of a loaded, linear-elastic, cube. Preliminary results for the deformation of a simulated, linear-elastic, cornea have also been achieved using the finite element approach. Author Keywords: continuum solid mechanics, corneal biomechanics, finite element method, intraocular pressure

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Format: 2024/03/29