VictorJuiz/thesis huggingface dataset:
Perovskite Semiconductor Nanostructures for Light Emission

Perovskite-based semiconductor materials have achieved remarkable progress over the past decade, and are now considered to be promising candidates for low-cost high-performance optoelectronic devices. Wide interest in this material system stems from its versatility, low density of and high tolerance to charge carrier traps, high charge carrier mobilities, and low cost of fabrication. Nanostructures offer a number of additional benefits for light emission applications including a wide range of bandgap tuning, bright photoluminescence, and, in cases, improved long-term stability. In this thesis, I investigate properties of perovskite nanostructures for light emission applications; my findings shed light on the remarkable performance of these materials, and provide insight into avenues to enhance further their light-emitting behaviour. First I develop and investigate a dot-in-matrix strategy that enables perovskite quantum dots to exhibit photoluminescence quantum yield of over 90% in the solid-state. Modeling and experimental characterization suggest that lattice matching between the quantum dots and the matrix contributes to improved passivation, while spatial confinement enhances the radiative rate. Next I investigate perovskite shells on quantum dots as a means to inhibit intradot Auger recombination. I demonstrate experimentally that MAPbI3 perovskite shelling decreases the rate of Auger recombination in PbS quantum dots by over 1 order of magnitude. I then explore morphological properties of perovskite quantum well thin films. I use in-situ methods during film formation to understand the mechanism by which the two-dimensional perovskites assemble, and I use these observations to explain the energetic and orientational distribution of perovskite quantum wells. Finally, I study the alignment of perovskite quantum well energy levels. I study their energetic band positioning and find that the work function can be altered by surface interface dipoles across ligands. As a result, perovskite quantum well interfaces can exhibit type-I or type-II alignment depending on the density of ligands on surfaces.

Keywords: Nanoscience
Perovskite
Photonics
Semiconductor
Advisor: Sargent, Edward H
Innovative Research Methods to Evaluate Effective Engagement with Consumer Mobile Health Applications for Chronic Conditions

Consumer mobile health applications (mHealth apps) hold enormous potential to provide effective, efficient, economical, and scalable chronic health care. The opportunities afforded by these interventions to positively disrupt traditional chronic care models are significant, but require a cumulative evidence base to inform policy and practice. Evaluating these interventions, however, presents unique challenges. Traditional research methods are poorly suited to accommodate the rapidly changing technology landscape, which requires mHealth apps to constantly evolve and update just to remain usable, let alone effective. Moreover, they cannot characterize the complex, multilevel, and temporally dense patterns of effective engagement required to realize improved outcomes. This program of research sought to (1) investigate the complexity of conducting innovative evaluations of consumer mHealth apps for chronic conditions, and (2) build a research analytics platform to streamline evaluations and optimize mHealth apps. We established in Study 1 that mHealth evaluation methodology has rarely deviated from common methods, despite the need for more relevant and timely evaluations. This finding led us to explore the potential of analytic research methods in Study 2, where we discerned that digital health innovators were gaining nuanced insights into engagement, but had not yet characterized effective engagement for improved outcomes. To support innovators with this effort, our research in Study 3 focused on designing, developing, and evaluating a resource to consolidate, analyze, and visualize analytic indicators of effective engagement. The Analytics Platform to Evaluate Effective Engagement with digital health interventions—APEEE for short—provided innovators with a means to characterize the breadth and depth of mHealth app engagement required to achieve intended outcomes. Motivated by the potential for APEEE to power data-driven research methods, we directed Study 4 toward studying the implementation of the platform—and research analytics more broadly—in digital health evaluative practice, and surfaced the rich complexity of engaging in this practice to evidence mHealth apps. Raising the standard of mHealth evidence may enable greater confidence in the causal effect of apps on improved chronic health outcomes. It is this opportunity afforded by innovative research methods to close the gap between promised and realized health benefits that is most meaningful.

Keywords: digital health
health services research
innovative clinical trials
mobile health
research analytics
Advisor: Cafazzo, Joseph A
Reduced-order Integral Equation Methods to Solve Complex Electromagnetic Problems

Despite vast advancements in computational hardware capabilities, full-wave electromagnetic simulations of many multiscale problems continue to be a daunting task. Multiscale problems are encountered, for example, when modeling interconnects in an integrated circuit or when simulating complex electromagnetic structures. In interconnect problems, the main challenge is to model the multiscale skin effect that develops inside the conductors at high frequency. Similarly, complex electromagnetic structures are multiscale because these surfaces are tens of wavelengths large, while each unit cell often contains subwavelength geometrical features. This thesis presents reduced-order integral equation methods to solve complex multiscale problems. For interconnect problems, it proposes a single-source surface integral equation method to model 2-D and 3-D conductors or dielectrics of arbitrary shape. In this approach, electromagnetic fields inside a conductor or a dielectric object are accurately modeled by a differential surface admittance operator and an equivalent electric current density on the object's surface. Since the proposed method does not use any volumetric unknowns, it is more efficient than volumetric methods encountered in the literature and commercial solvers, which require a fine mesh to model the skin effect. Furthermore, since the proposed approach is single-source, it is more efficient than other surface methods in the literature that require both equivalent electric and magnetic current densities. Numerical results show that the proposed method can be over 100x and 20x faster than commercial FEM solvers for 2-D and 3-D problems, respectively, while consuming significantly lower memory. The proposed surface method for conductors and dielectrics is further generalized to develop the so-called macromodeling technique to simulate complex scatterers. In this technique, a heterogeneous scatterer composed of dielectric and PEC objects is accurately modeled by equivalent electric and magnetic current densities that are introduced on a fictitious surface enclosing the element. The crux of the technique is to solve for unknowns only on the fictitious surface, instead of the scatterers, which results in fewer unknowns. Numerical results show that the proposed macromodeling technique can efficiently simulate electrically large reflectarrays composed of square patches and Jerusalem crosses, that are difficult to simulate even with commercial solvers.

Keywords: Integral equations
Surface Methods
Advisor: Hum, Sean V.
Triverio, Piero
Learning Differentiation in Music Education: Theory and Practice

The purpose of this study is to use a Dual-Phased Integrated Summative and Directed Qualitative Content Analysis to determine if keywords and themes related to differentiation and varied learner needs in mixed ability classroom contexts are present in the core construct of praxial curriculum theory and the Reflective Musical Practicum curriculum design, an extension of the philosophy of praxial music education to practice. The results showed that while keywords related to differentiation were not significantly present in the body of the selected text, evidence of differentiation thematically emerged in the comparative analysis of the curricular design phases. The analysis further showed that the foundation of praxial curriculum theory and the Reflective Musical Practicum curriculum design is content driven, a complex, in-depth, and rigorous educative curricular construct of MUSICS and MUSICING. By analyzing the results of the keyword codification and integrating the foundational tenets, concepts, and strategies of differentiation instruction and curriculum theory with praxial curriculum theory, a new working curriculum design theory emerged from the expansion: Learning Differentiation Music Education Curriculum Theory. The working definition of LDMET was used as the foundation for curriculum development, constructed from the key concepts of differentiation and praxial curriculum theory, to inform pre-service music education course preparation addressing varied learner needs in mixed ability inclusion contexts.

Keywords: curriculum development
differentiation
instructional strategies
mixed ability
praxial music education
special needs learners
Advisor: Dolloff, LoriAnne
The Navier-Stokes strain equation with applications to enstrophy growth and global regularity

This thesis derives an evolution equation for the symmetric part of the gradient of the velocity (the strain tensor) for the incompressible Navier-Stokes equation. We use this equation to obtain a simplified identity for the growth of enstrophy for mild solutions that depends only on the determinant of the strain tensor, not on the nonlocal interaction of the strain tensor with the vorticity. The resulting identity allows us to prove a new family of scale-critical necessary and sufficient conditions for blow-up of the solution in finite time Tmax < +∞, which depend only on the history of the positive part of the second eigenvalue of the strain matrix. Since this matrix is trace-free, this severely restricts the geometry of any finite-time blow-up. This regularity criterion provides analytic evidence of the numerically observed tendency of the vorticity to align with the eigenvector corresponding to the middle eigenvalue of the strain matrix. We then consider a vorticity approach to the question of almost two-dimensional initial data, using this same identity for enstrophy growth and an isometry relating the third column of the strain matrix to the first two components of the vorticity. We prove a new global regularity result for initial data with two components of the vorticity sufficiently small. Finally, we prove the existence and stability of blowup for a toy model ODE of the strain equation.

Advisor: McCann, Robert
Re-imagining Black Masculinity: Praxis of Kenyan Men in Toronto

This study examined Black masculinity, the representation of Black men, and by extension the Black community. Black men in North America historically have been racially targeted and profiled in employment and education (school/prison pipeline). Black masculinity scholarship has actively represented this demography through diverse scholarships. While this may be the case, the opposite is equally true; the scholarly lens does not provide the overall picture of Black men. This exploratory/descriptive qualitative Afrocentric Indigenous narrative study applied post-colonial, anti-colonial, and critical masculinity theoretical frameworks to argue that Black masculinity is implicated in epistemological violence and imperialism. The study encompassed semi-structured interviews with 10 participants (Kenyan men in Toronto), allowing for open expression of their experiences. The Kenyan story has been missing in action; that is, the Kenyan racial experiences in immigration, education, and labour remain expunged and absent. Black masculinity has not focused on accents as a racial and gendered concept of erasing Kenyan men from social and political processes. The study is framed around the limits of Black masculinity and looks at immigration, education, and labour policies in Canada and how they expel Kenyan men from the body politic. Kenyan men that were interviewed said that though they are Black they are also African based on the complex act of accent multiplier.

Keywords: accent
Black masculinity
Blackness
Diaspora
Indigenous
Masculinities
Advisor: Dei, George
Inside Open Government Data Curation: Exploring Challenges to the Concept of a ‘Designated Community’ through a Case Study of the City of Toronto

As digital curation continues to evolve as a field of research and practice, questions have emerged regarding the applicability of a key concept drawn from the field’s origins in digital preservation. Established models of digital preservation use the concept of a ‘designated community’ of potential future users as a reference point for the delivery of digital information. It is unclear, however, whether the concept of a designated community holds the same importance in curation situations where long-term preservation is a less central concern or how curation functions when there is no clear designated community to which curation services can be targeted. This dissertation explores these themes in the context of Open Government Data (OGD) curation. Here the mandate is to make datasets produced by the public sector available to anyone for any use, as part of the larger project of open government. In doing so, OGD curation presents a challenge to existing ways of conceptualizing digital curation, as drawn from digital preservation. Using the City of Toronto as a case study, this research investigates OGD curation processes and the influence conceptions of a ‘designated community’ of future users and their use of the data have on those processes. The study was structured using Cultural-Historical Activity Theory (CHAT) as a theoretical framework and data was collected using three methods: semi-structured interviews with curation participants and OGD advocates, analysis of documents, and the observation of public events. The findings revealed three distinct processes central to the interests of the study: the process of releasing OGD; the development of an Open Data Master Plan to revitalize the City’s open data program; and the creation of an OGD portal to help users’ access and engage with data. Conceptions of the data use and users present at the study site were drawn from the broader discourse surrounding OGD. Furthermore, this reference to OGD discourse and the innovations introduced by curators can be interpreted as a response to the challenge of curating data for a diverse audience.

Keywords: City of Toronto
Designated Community
Digital Curation
Open Data
Open Government
Advisor: Foscarini, Fiorella
From Function to Flourishing: Neo-Aristotelian Ethics and the Science of Life

Neo-Aristotelian ethical naturalism purports to place moral virtue in the natural world by showing that it is an instance of natural goodness—a kind of goodness supposedly also found in the biological realm of plants and non-human animals. One of the central issues facing this metaethical view concerns its commitment to a teleological conception of the nature of life that seems radically out of touch with the understanding of life in modern biology. In this dissertation, I aim to mend the relationship between neo-Aristotelian ethics and the science of biology by way of three contributions: First, I argue that contrary to what many contemporary neo-Aristotelians have claimed, the science of biology is relevant to assessing central commitments of neo-Aristotelian naturalism regarding the domain of life. Second, I provide new foundations for neo-Aristotelian naturalism by engaging recent and unexplored work in philosophy of biology on theories of function and the nature of living organisms. Lastly, I develop and defend a novel account of the neo-Aristotelian concept of natural goodness that is distinctive for incorporating our scientific understanding of the nature of life.

Advisor: Tenenbaum, Sergio
Walsh, Denis M.
Silicon and Silicon Nitride Photonic Devices and Platforms for Very Large-scale Photonic Integration

Photonic integrated circuits (PICs) on silicon (Si) hold the promise of densely integrated optical circuitry and low-cost, high-volume manufacturing on complementary metal-oxide semiconductor (CMOS) fabrication infrastructure. However, the high index contrast nature of the platform presents numerous obstacles for reliably realizing very large-scale PICs. In this thesis, we present photonic devices and platforms for addressing the challenges of dimensional and thermal tolerances, polarization dependence, and low-loss passive devices. Firstly, we present design strategies for improving the dimensional tolerances of devices fabricated on Si foundry platforms and confirm their efficacy through wafer-scale measurements. We exploit correlated dimensional fluctuations to design directional couplers with variation-tolerant splitting ratios, and we incorporate adiabatically widened waveguide bends within microring resonators to reduce the intradie and across-wafer spread in the resonant wavelength without compromising the quality factor. Secondly, we propose to use silicon nitride (SiN) in place of Si for low-loss, variation-tolerant, and thermally insensitive passive devices. On a SiN platform, we demonstrate a robust polarization-insensitive wavelength demultiplexer formed from cascaded Mach-Zehnder interferometer lattice filters for optical receiver applications. The design, which uses zero-birefringence waveguides and optimized directional couplers, provides a promising alternative to polarization diversity circuits, thereby reducing circuit footprint and complexity. Thirdly, we show how the superior passive characteristics of SiN can be combined with Si for active functionality in a SiN-on-Si photonic platform. We design and characterize a custom trilayer platform incorporating two SiN layers atop a Si layer. We develop the passive optical elements essential to the platform operation, including low-loss interlayer taper transitions for optical power transfer between layers and ultra-low-loss, low crosstalk waveguide crossings to facilitate routing. Using three layers breaks the trade-off between interlayer taper loss and crossing loss, and our trilayer platform is shown to be especially suitable for very large-scale PICs comprising hundreds or thousands of elements. To illustrate the platform utility, we fabricated photonic switches which represent some of the largest PICs ever attempted. The electro-optic switch cells operate with nanosecond scale speeds, and we present designs for a single polarization 16x16 switch and a polarization-independent 4x4 switch.

Keywords: Optoelectronic integration
Photonic integrated circuits
Polarization-independence
Silicon nitride
Silicon photonics
Variation-tolerance
Advisor: Poon, Joyce K. S.
Contiguous Conflict-free Link Scheduling for Efficient V2X Communication in the Next Generation of Wireless Networks

Cellular V2X, the "Vehicle to Everything" standard, defines a framework for practically feasible information exchange among vehicles and other network entities. This interaction is proved to bring in substantial economic and ecological benefits. In the main mode, LTE V2X relies on a central scheduler. As an important resource management problem, minimizing the consumed resources by this scheduler in a conflict-free manner is NP-hard. Conflict-free scheduling assigns separate resources to the conflicting links and can enjoy from opportunistic resource reuse. In order to solve this NP-hard problem, existing methods, under different simplifications, apply graph theoretic algorithms, namely, graph-coloring and shortest-path. These methods seem to be incapable of satisfying the LTE and 5G V2X communication requirements mainly due to their reliance on simplifications that are unnatural to V2X environment. In this thesis, a novel point of departure is proposed for this NP-hard problem that models scheduling as a generalized Traveling Salesman Problem (TSP). Eliminating the need for such simplifying constraints, we design heuristic algorithms for polynomial-time approximation of this problem. The resulting schedulers can be flexibly employed in general V2X network topologies with no packet segmentation, which leads to minimizing control information overhead. Due to scalability and a close-to-optimal resource utilization, compared to the existing literature that is achievable with manageable complexity, our proposed schedulers are desirable for LTE V2X and the upcoming 5G systems.

Advisor: Valaee, Shahrokh
Walking Toronto's Red Road: The Story Pathways of Indigenous Social Workers

Abstract: A Long Story Short "The truth about stories is that’s all we are. ‘You can’t understand the world without telling a story,’ the Anishinaabe writer Gerald Vizenor tells us. ‘There isn’t any centre to the world but a story’" (King, 2003, p. 32). Tap. Tap. ‘Is this thing on?’ Clears throat. Pushing his way to the top of the paragraph, he continues, ‘I figure I would try to get to you first.’ Snicker. ‘As this is really all about me, anyways,’ Trickster says, fluttering his eyelashes, resting one hand on his chest. ‘I mean, sure, I suppose we are traveling the story pathways of Indigenous social workers in Toronto,’ he muses, lifting his hand to his chin. ‘But social work in North America is a dynamic tale of oppression and resistance,’ he pauses to think. ‘So, the ten (10) short stories shared here, created with the participants of this research journey, really are a collection of Trickster tales,’ he states, regaining all confidence. ‘And these stories, like Trickster tales, carry good lessons in their disorder,' Trickster says, slapping his knee. Cackle. Snort. Phew. After regaining some composure, he looks up off the page and back towards the reader. Tap. Tap. ‘Storytelling and land are interconnected with each other and to this anti-colonial endeavour’ Trickster says, eyebrow raised. ‘Somewhere between the significance of petroglyphs and carving your name into wet cement, these story landmarks will guide us in a journey through the relationship Indigenous social workers have with their profession,’ he says, slinking his way down the page. ‘Guided by an Indigenous research methodology, we take a journey through story, exploring the pathways Indigenous social workers create through their work,’ Trickster says. ‘Story pathways with some unexpected impacts and destinations, for Indigenous peoples, social work, and research itself,’ he smirks. ‘So, come walk along Toronto’s Red Road, aided by the stories of those who have gone before us, guiding and perhaps even cautioning we future travelers.’ Keywords: Indigenous, Aboriginal, Social Work, Stories, Landmarks, Story Pathways, Anti-Colonial, Research Methodology, Trickster, Toronto

Keywords: Aboriginal
Anti-colonial
Indigenous
Indigneous Research Methodology
Social Work
Storytelling
Advisor: Restoule, Jean-Paul