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Adaptive step sizes and implicit regularization in optimization models
No full textGiven the ever-increasing size of machine learning models, better optimization algorithms are needed to improve computation efficiency. Despite significant recent progress having been made, there is a lack of understanding of the general working principles behind common optimizers for complex tasks such as neural network training. There are two criteria to be considered when measuring the performance of an optimizer: 1. the convergence speed or the rate of training-loss decrease; 2. test accuracy of the converged solution. Given these criteria, this thesis focuses on three relevant ingredients: data sampling for (stochastic) gradient computation, step sizes, and optimization implicit bias.
We first consider a commonly used sampling-without-replacement scheme for computing the stochastic gradient, known as random reshuffling (RR). Despite its success in training deep neural networks, its theoretical justifications have only been studied recently. In the over-parameterized setting, it has not been shown that RR achieves the linear convergence rate as stochastic gradient descent (SGD) does. We bridge this gap by showing the rate of RR is indeed linear and can be faster than that of SGD.
Stochastic Polyak (SPS) and line-search (SLS) step sizes are known to converge fast under over-parameterization, thanks to their adaptivity to the local curvature of the loss. However, without over-parameterization, there is no guarantee that they would converge to the exact solution. Given this, we first extend SPS and SLS to the non over-parameterized setting. The advantage of our modifications is that the step sizes are not required to be monotonically decreasing. We then propose variants of SPS and SLS for bilevel optimization which involves tuning two step sizes.
Previous works that studied optimization implicit bias have focused more on the binary classification setting. However, machine learning applications are typically multiclass. To this end, we study a family of optimization algorithms known as normalized steepest descent in linear multiclass classification with separable data. This includes several popular algorithms. We show that their iterates converge to the max-margin defined with respect to the norms that are used to define the algorithms.Science, Faculty ofComputer Science, Department ofGraduat
Deconstructing the collaborative for academic, social, and emotional learning (CASEL) framework and the Happiness Curriculum in the context of educational neoliberalism and emotional governance
No full textThis thesis examines Social-Emotional Learning (SEL) through a comparative analysis of the Collaborative for Academic, Social, and Emotional Learning (CASEL, 2020) framework and Delhi’s Happiness Curriculum (HC, 2019). It addresses two research questions: What implicit values and assumptions about emotions are embedded within the CASEL and Happiness Curriculum frameworks, and how does the Happiness Curriculum in India adapt, resist, or reproduce CASEL’s approach to social emotional learning? and How does SEL function as a tool of emotional governance by using governmentality to shape students into self-regulating individuals in ways that align with broader socio-economic systems? Using Fairclough’s three-dimensional Critical Discourse Analysis together with a Foucauldian lens of governmentality, the study begins with within-document description and keyword analysis for each framework, moves to cross-document comparison to identify convergences and adaptations, and then explains the findings. The findings indicate that by centering competencies like self-awareness, self-management,and “learning outcomes,” both frameworks organize emotions as skills to be optimized, individualize responsibility for improvement, and translate well-being into measurable performance targets. Read through governmentality, these patterns normalize self-monitoring and position well-being alongside achievement and readiness, shaping students as self-regulating individuals. Across both frameworks, the discourse privileges “positive” feelings such as calm, happiness, and gratitude, with limited recognition of discomfort, anger, or grief as part of learning and social life. The thesis concludes by outlining implications for practice and design: broaden the emotional repertoire recognized in SEL frameworks, reduce the reliance on learning outcomes as proxies for emotional growth, and support participatory, context-grounded approaches that attend to well-being and collective flourishing within and beyond school.Education, Faculty ofEducational Studies (EDST), Department ofGraduat
A laser-ablation dual-comb spectrometer for detection of critical minerals
No full textRare-earth elements and other critical minerals are key components to transition economies towards a greener and more sustainable footprint. In all
phases of mining operations (exploration, extraction and ore processing),
real-time and stand-off sensors with low detection thresholds have the potential to improve the economic and environmental impact of producing critical
minerals. Upgrading ore body modelling as well as realizing sorting and processing efficiencies are two use cases. Laser-ablation dual comb spectroscopy
is a broadband technique that uses two mode-locked lasers to measure the
absorption spectrum of laser-produced plasmas. It requires minimal sample preparation, has millisecond measurement times, and has the resolution
of continuous wave laser based spectroscopies. These properties make it
an ideal candidate for real-time sensing in mining workflows, yet its potential in mining remains unexplored. This work describes the construction,
characterization, and use of a laser-ablation dual comb spectroscopy system optimized for detecting rare-earth elements in ores. The system was
built using two commercial mode-locked lasers whose repetition rates were
stabilized with respect to one another for measurement repeatability. The
systems measurement spectrum is centered around the second harmonic of
the two mode-locked lasers, ranging from 518-532 nm, and its spectral resolution ranges from 1-10 pm. Its ability to detect rare earth elements in
mineral matrices was tested by measuring a dilution series of pellets made
from calibrated ore powders with traces of CeO₂, La₂O₃, and Sm₂O₃. Limits of detection of Ce, La, and Sm were estimated from the measurements
to be 50 ± 1 ppm, 65 ± 0.1 ppm, and 63 ± 0.1 ppm, respectively.Science, Faculty ofPhysics and Astronomy, Department ofGraduat
Social media platforms increasingly disclose when news is fake or misleading. Is it helpful?
No full textSocial media platforms have increasingly adopted fact-checking labels to combat the spread of misinformation. However, existing research has focused primarily on whether these interventions reduce belief in false claims, overlooking a potentially more harmful effect: the activation of prejudice against targeted groups. This study investigates whether fact-checking labels prevent prejudice activation when users encounter fake news targeting Muslims. Using an experimental design with three conditions: undisclosed fake news, disclosed (fact-checked) fake news, and a control group, I surveyed over 1400 participants across two studies to measure attitudes toward Muslims after exposure to fabricated anti-Muslim content. Results were inconsistent across my surveys: while the first study showed that disclosure significantly reduced negative attitudes compared to undisclosed fake news (p=0.009), the second study failed to replicate this effect (p=0.55). Notably, both disclosed and undisclosed groups consistently clustered together and separately from the control group, suggesting that mere exposure to inflammatory content may influence attitudes regardless of fact-checking. These findings indicate that current platform interventions may be insufficient to prevent prejudice activation, even when they successfully correct false beliefs. The study suggests a societal need for alternative approaches beyond labeling to protect marginalized communities from the harmful effects of orchestrated disinformation campaigns.Arts, Faculty ofPolitical Science, Department ofGraduat
Mitochondrial biogenesis and pathway activation during follicular lymphoma transformation to diffuse large B-cell lymphoma
No full textThe full abstract for this thesis is available in the body of the thesis, and will be available when the embargo expires.Science, Faculty ofGraduat
The development of in-situ testing infrastructure and characterization of hydrogen embrittlement in pipeline steels
No full textHydrogen is being considered for low-carbon energy transport, but assessing pipeline readiness requires testing infrastructure and mechanical characterization under gaseous hydrogen. This dissertation addresses both needs by (i) designing and commissioning a modular gas management system with two complementary in-situ setups, a hollow-specimen setup and an autoclave-based testing setup, and (ii) characterizing hydrogen embrittlement in three pipeline steels: a vintage CSA Z245.1 Grade 290 and two modern API 5L X60 steels from different mills.
Slow strain rate tensile results show that Grade 290 loses ductility rapidly with increasing hydrogen pressure, whereas the X60 steels retain significantly higher ductility. The hydrogen embrittlement index for X60I indicates a moderate reduction, while X60J shows only slightly higher susceptibility depending on sampling position. Through-thickness variations in X60J, particularly at the inner and middle wall, where segregation and banding are most pronounced, increased secondary cracking was observed.
Under cyclic loading, Stage II behaviour observed in air is relatively insensitive to microstructural differences, but hydrogen accelerates crack growth at lower stress intensity ranges. Fatigue crack growth rate results identify X60J as the preferred modern steel for hydrogen service because its banded bainitic ferrite colonies deflect advancing cracks and slow propagation, extending fatigue life compared to X60I. In contrast, Grade 290 transitions earlier toward unstable crack growth, confirming its lower fracture toughness and less suitability for hydrogen repurposing.
The developed infrastructure enables safe, repeatable, and service-relevant in-situ testing under gaseous hydrogen, forming a framework for consistent evaluation of hydrogen-assisted degradation. The results demonstrate that microstructural characteristics, rather than the nominal grade, govern hydrogen performance. Modern X60 steels can be viable candidates for hydrogen transport, but each pipeline's heat and wall position must be independently verified to confirm readiness.
Overall, this research establishes the first academic capability in Canada for gaseous hydrogen embrittlement testing and bridges a major technological gap in evaluating pipeline materials for hydrogen service. It provides a foundation for future national research supporting pipeline repurposing, qualification protocols, and Canada’s broader transition toward a hydrogen-based energy infrastructure.Applied Science, Faculty ofEngineering, School of (Okanagan)Graduat
Directional anomalous skin effect in ReO₃
No full textRhenium oxide (ReO₃) is one of the most highly conducting metals, and has the lowest reported low-temperature residual resistivity of any oxide material. This property endows it with a remarkably long low-temperature electronic mean free path, comparable to those seen in the ultrapure delafossites. In the quasi-2D delafossite material palladium cobaltate (PdCoO₂), recent broadband microwave spectroscopy studies have observed a novel directional anomalous skin effect (ASE). These studies found that the anisotropy of the ASE in PdCoO₂ is influenced by the relative alignment of surface currents and the facets of its Fermi surface. This anisotropy even extends to the frequency-dependence of the surface resistance. Recently developed nonlocal Boltzmann transport models are able to describe its skin effect response, indicating that it falls between the ballistic and viscous-like transport regimes.
The success of this new model motivated us to investigate the anomalous skin effect response in ReO₃, and in doing so, test the predictions of the generalized theory of the skin effect in a material distinct from PdCoO₂ in two main ways: it has a more complex fully three-dimensional electronic structure with multiple Fermi surface sheets of different character, and has potentially different defect scattering behaviours. As an additional test to these models, we study samples of ReO₃ that have been irradiated with high-energy electrons to introduce homogeneous point-like defects.
Our experimental results reveal a rich anisotropy in the anomalous skin effect response in ultrapure ReO₃ that depends not only on the direction of surface currents with respect to crystallographic direction, but also on the direction of electromagnetic propagation. The novel skin effect models accurately predict the response for some situations, but fail in others. We suggest possible reasons for this discrepancy, by considering the Fermi surface geometry, and referring to de Haas-van Alphen measurements reported in the literature. Furthermore, our measurements of high-energy electron-irradiated ReO₃ samples found a skin effect response in the diffusive regime, confirming that a low residual resistivity is a necessary condition of the phenomenology observed in the pristine ReO₃ samples.Science, Faculty ofPhysics and Astronomy, Department ofGraduat
The development and evaluation of "Being There", an online well-being program for support networks of rural adults 50 years and older with mental health concerns
No full textSocial support in relationships is crucial for the wellbeing of adults aged 50 and older with mental health concerns (MHCs), particularly in rural communities with limited resources. Family and friends who provide this support, referred to as support partners, often feel overwhelmed and may benefit from additional resources. This dissertation includes two studies focused on the development and evaluation of Being There, a self-guided online program designed to improve support partner well-being and mental health literacy. The program included six modules that addressed psychoeducation, stress, coping strategies, communication, resources, and included community building components. Study I evaluated the feasibility and acceptability of the program in a small sample. Support partners of adults aged 50 and older with MHCs living in rural British Columbia (n = 9) completed pre- and post-program surveys and participated in a focus group. Overall, the program was found to be feasible and acceptable, though participants suggested changes to program content and logistics. Quantitative data showed variability in outcomes, consistent with qualitative feedback highlighting diverse individual needs in online learning. The program was revised based on this feedback. Study II evaluated the feasibility, acceptability, and effectiveness of the revised program using similar procedures. Participants (n = 21) again rated the program as feasible and acceptable, though learning needs and accessibility challenges varied. Qualitative feedback emphasized key takeaways and highlighted both strengths and weaknesses of the program’s social components, including Coffee Chats and the Discussion Board. Attrition analyses indicated that participants experiencing more emotional distress at baseline were more likely to drop out, suggesting that those who may benefit most from the program may also face greater barriers to participation. Paired samples t-tests revealed limited program effectiveness. There was a significant increase in mental health literacy and a trend toward reduced guilt about experiencing negative emotions towards others. Exploratory regression analyses found that improvements in communication and emotion regulation were associated with reductions in caregiver burden. Although the small sample size limited statistical power, findings underscore the importance of revising the program further to better support participants with elevated distress, and enhancing engagement through targeted skill development sessions.Arts and Social Sciences, Irving K. Barber Faculty of (Okanagan)Psychology, Department of (Okanagan)Graduat
A curriculum of revelation : Jean-Luc Marion’s saturated phenomena in the classroom
No full textBased on my experiences as an educator, I believe there is more happening in the classroom than we can easily think about and put into words. Provoked by curriculum theorist Dwayne Huebner’s idea of the “moreness” of education, I use phenomenologist Jean-Luc Marion’s theorizing about revelation to describe the educational event as saturated with meaning and, so, dwelling outside of the classical phenomenological understanding of experience. I argue that a “moreness” beyond current understanding, experience saturated with meaning that exceeds our ability to know it, is key to the most humane and aspirational aims of education. I ask the following questions: If we extend our understanding of experience to include revelation, how—if at all—does this change our understanding of an educational experience? If we think about the nature of educational experiences in terms of revelation, what impact might this have on how we think about curriculum as a lived, classroom experience? I also engage with the challenge of communicating and reflecting upon an experience that in its “moreness” exceeds or evades comprehension and so cannot be expressed with conventional language. What follows from asserting the possibility of a revelatory experience—an experience that originates from outside of and in excess of our intention—is a need for a way to express an experience of revelation—an experience that by definition remains beyond current conceptions. To this end, I employ poetics as not only an interpretive but also an observational method. Starting with naturalistic observations of my own and others’ classrooms, I craft poetic descriptions to sketch aspects of the “more” that is happening there. I include these poetic renderings throughout the manuscript, offering them in support of my conception of a form of educational experience that is initiated not by the subject, but by encounter with absolute otherness, an excess or moreness of meaning beyond the subject’s ability to comprehend. I call this encounter a curriculum of revelation.Education, Faculty ofCurriculum and Pedagogy (EDCP), Department ofGraduat
Investigating sex differences in diaphragm blood flow during exercise hyperpnea in humans
No full textThe full abstract for this thesis is available in the body of the thesis, and will be available when the embargo expires.Health and Social Development, Faculty of (Okanagan)Health and Exercise Sciences, School of (Okanagan)Graduat