VictorJuiz/thesis huggingface dataset:
Origami-inspired Mechanical Metamaterials

Folding paper into a repeated, tessellated, origami pattern can increase the paper’s strength. Using these origami patterns as inspiration for the design of structural engineering materials can similarly enhance the materials’ properties. There are multiple aspects of origami-inspired material designs that can affect their strength and performance, such as the chosen origami fold pattern, the dimensions of the pattern, and the material from which the pattern is fabricated. Common patterns that have previously been shown to have advantageous properties include Miura, Ron Resch, Kresling, and Yoshimura origami patterns.In this thesis, three novel origami fold patterns were designed, parameterized, and mechanically tested. The three patterns included a triangular-based pattern, a rectangular-based pattern, and a square-based pattern. The first study parameterized the geometries of the novel triangular and rectangular based origami, and proved the patterns had higher specific strength moduli than a previously tested Ron Resch pattern made from the same material. The rigid polylactic acid samples fractured during impact testing, leading to the second study which used a rubber-like material to fabricate flexible triangular, rectangular, and square-based origami sheets. These sheets were capable of absorbing loads from multiple impacts without fracturing and were more effective than unpatterned sheets at absorbing impact loads. The third study focused on analysing a two-level, full-factorial, parameterization for the triangular origami patterns. The results of this analysis defined how the overall shape and curvature of the origami sheet varied as the fold angle was changed. The fourth study combined flexible and rigid materials to create multi-material origami sheets comparing the triangular, square, and Miura origami patterns. The results showed that the triangular pattern had the highest compression strength, with the Miura pattern being next strongest. The final study creates heat activated shape memory origami tubes that would be ideal for use as space-saving actuators. Overall, three new origami-inspired patterns were created in this thesis: a triangular-based pattern, a rectangular-based pattern, and a square-based pattern. They were shown to have high strength-to-weight ratios and were effective at absorbing impact loads. Consequently, the materials designed in this thesis would be ideal for lightweight structures and protective equipment.

Keywords: 3D printing
Compression testing
Fracture mechanics
Impact testing
Origami-inspired materials
Advisor: Naguib, Hani E
Infinite Shoreline for Orchestra

Infinite Shoreline, by Colin Spencer McMahon, DMA 2021Graduate Department of Music, University of Toronto Infinite Shoreline is a composition for orchestra in one movement that explores the mathematical, philosophical, and emotional implications of the “Coastline Paradox”. The “Coastline Paradox” highlights the difference between our experience of the natural world, and reality as observed by fractal geometry. A fractal is a curved line that can have no discernible length, its complexity changes with scale. If you were to measure the distance between plotted points on a coastline and then sum the total, the total would increase as you increased the number of plotted points such that as the number of points approaches infinite so does the length of the coastline. Infinite Shoreline explores ornamentation as a method for melodic development, wherein a broad, simple melody is made increasingly complex whist still following the same essential landmarks. Ornamentation is used as an allegory for the infinite, fractal nature of a coastline. As the melody increases in complexity so too does the linear harmonic collections that contain it, moving from pentatonic, through to 12 tones and beyond to micro-tonal as the melodic complexity “approaches infinite” so-to-speak. If the coastline is a melody, the harmonic and textural contexts in which we hear it is the ocean; constantly shifting, on minuscule, local, and large scales. At the point of contact the ocean is in constant flux (waves), it shifts dramatically with the moon, and the ocean is slowly rising (global warming.) This constant motion influences the make-up of the coastline as defined as “the place where the ocean and land meet”, but also on the land itself through eroding and depositing earth. In musical terms, the turbulent rising and falling of orchestral texture and harmonic density shifts the otherwise firm landmarks of the melody. Approximate duration: 14’ 00”

Keywords: Coastline Paradox
Fractals
Orchestra
Advisor: Kulesha, Gary
Entrepreneurial Income and Wealth Dynamics

This thesis studies wealth inequality, entrepreneurship, and financial frictions. The first chapter focuses on how the uninsurable nature of entrepreneurial risk reduces entrepreneurial activity and affects aggregate output, productivity, and the distribution of wealth. I build a model where individuals choose to become workers or entrepreneurs, and where entrepreneurs choose how risky a business to start. My model features two distinct financial frictions. First, a missing market for entrepreneurial risk prevents entrepreneurs from insuring themselves against their income risk and the risk of business failure. Second, borrowing constraints limit the size of an entrepreneur's business. I contribute to a literature on financial frictions and entrepreneurship by studying the missing market for entrepreneurial risk. The model is calibrated using micro data on new U.S. firms. I find that completing the missing market for entrepreneurial risk improves aggregate productivity by 9% and reducing the share of wealth held by the wealthiest 1% by two thirds. In a policy experiment, a partial insurance scheme for unsuccessful entrepreneurs can increase aggregate productivity and output by encouraging entrepreneurs to start riskier businesses. In my jointly-authored second chapter, we study how the composition and distribution of household wealth affects the distribution of MPC's. We document facts in the Survey of Consumer Finances about the composition of household portfolios between housing, mortgage debt, and more liquid financial assets over the distribution of wealth. We then build a rich quantitative model with heterogeneous returns that matches both the composition and concentration of wealth. We use the model to decompose the importance of return heterogeneity, long-term fixed rate mortgages and refinancing, and owner-occupied housing for the average MPC and find that each factor significantly contributes to generating a higher average MPC, with a cumulative effect of 0.25 percentage points. In my third chapter, I study how different government policies can promote entrepreneurship by mitigating financial frictions. In the presence of both a missing market for entrepreneurial risk and borrowing constraints, I compare how entrepreneurial insurance, a universal basic income, government-backed business loans, entrepreneurial income tax deductions, and tax progressivity will impact the decisions of potential entrepreneurs.

Advisor: Kuruscu, Burhan
Kambourov, Gueorgui
Blind Spots in Personality Traits and Interpersonal Problems: The Roles of Narcissism and Self-esteem

Across clinical theory, clinical diagnostic criteria, and social/personality psychological research, narcissism has been conceptualized as having pathological presentations as well as normative, adaptive presentations that align more closely with self-esteem. Previous research has demonstrated that narcissistic individuals have some awareness about how others view them. However, much of this research has focused exclusively on grandiose and normative presentations of narcissism. Given these various accounts of narcissism and the general findings of meta-accuracy research focusing on its grandiose presentation, I sought to examine how pathological narcissism and both of its grandiose and vulnerable dimensions are related to blind spots in self-knowledge compared to more normative and adaptive presentations of narcissism. Moreover, given the relationship between normative narcissism and self-esteem, I also sought to examine how narcissism and its various presentations are related to blind spots in self-knowledge in comparison to self-esteem. In the first study, I examined how narcissism and self-esteem moderate meta-accuracy for personality traits and interpersonal problems in a university sample. In the second study, I sought to replicate the first study in an adult community sample while also controlling for depressive symptoms and cognitions which are often comorbid in vulnerable narcissism. For personality traits, people with higher self-esteem were more accurate in their understanding of their reputations, tended to assume that other people see them as more normative, and tended to assume that they were more transparent with others. Conversely, people higher in pathological narcissism and its vulnerable dimension were less accurate in their understanding of their reputation and tended to assume that others saw them as less normative. Normative and grandiose narcissism were inconsistently associated with bright spots and blind spots in people’s self-knowledge. For interpersonal problems, people higher in vulnerable narcissism tended to assume that they were less transparent with others, especially when controlling for depression symptoms and dysfunctional attitudes. Overall, both self-esteem and narcissism were inconsistently associated with bright spots and blind spots in people’s reputations about their interpersonal problems. These findings suggest that a more authentic positive self-image is conducive for understanding of one’s reputation relative to a more pathological positive self-image.

Keywords: Narcissism
Self-esteem
Self-knowledge
Advisor: Fournier, Marc A
The Work of Getting Better: An Institutional Ethnography of an Early Psychosis Intervention Clinic

The imperative to provide recovery-oriented services in mental healthcare settings has become foundational to mental health policies world-wide. However, in the context of psychiatric services, historically characterized as paternalistic and coercive, the translation of recovery policy into practice is complex, challenging and unevenly taken up. Early intervention services for young people experiencing a first episode of psychosis adhere to a recovery-oriented approach that aims to be client-centred, flexible and collaborative, empowering young people with the right and responsibility to be engaged in shared decision-making about their treatment options, which involve low-dose medication and psychosocial services. However, how these recovery practices unfold in young peoples’ interactions in early psychosis intervention (EPI) programs is not clear. In this study, I employ an institutional ethnographic approach to explore how the social organization of an EPI clinic coordinates young people’s everyday work of recovery. Methods included over 110 hours of ethnographic observation, in-depth interviews with 27 participants (18 clinic staff, four young people and five family members) and textual analysis of clinic documents (e.g., case files, administrative forms, policy reports). I provide an ethnographic description of “what actually happens” in young people’s interactions with service providers of an EPI clinic situated in Ontario, Canada. Findings detail how institutional processes shaped by the medication adherence discourse produced a disjuncture between service providers intent to provide recovery-principled care and young people’s experiences of medication uptake via institutional relations of informal coercion. In a related disjuncture of conflicting directives and objectives that govern the clinic, this analysis also outlines how the clinic manager’s and staff’s resistance to hospital rulings that impeded EPI policy principles were part of the extended sequence of activities that produced trust. These findings have important implications for shifts at the system level in terms of medication management and an emphasis from risk management and quality governance to an organizing framework based on trust.

Keywords: Canada
early psychosis intervention
institutional ethnography
medication adherence
recovery
trust
Advisor: Boydell, Katherine M
Hyperpolarized 129Xe Magnetic Resonance Spectroscopy and Imaging of Blood Oxygenation and Gas Exchange in Rats

Hyperpolarized 129Xe gas is a safe, non-reactive contrast agent for MRI. Once inhaled, 129Xe dissolves through the lung parenchyma and into the pulmonary blood. The 129Xe is then transported to peripheral organs such as the brain via the vascular system and, when in the brain, 129Xe freely dissolves across the blood brain barrier into the brain tissue. This route from the lungs to the brain tissue is analogous to that of oxygen, making 129Xe a good contrast agent for in vivo imaging of gas transfer and blood flow. Furthermore, 129Xe binds to the hydrophobic spaces of haemoglobin. Haemoglobin changes its conformation when it binds to oxygen, causing measurable changes in the chemical shift of 129Xe dissolved in red blood cells. This thesis presents experiments that exploit these properties of 129Xe to measure blood oxygenation and gas transfer at the lungs and brain. First, a chemical shift saturation recovery pulse sequence was used to acquire spectra of 129Xe dissolved in the lungs of healthy control rats as well as rats exposed to a hyperoxia/intermittent-hypoxia model of bronchopulmonary dysplasia. The results showed that the red blood cell chemical shift was lower in the exposed cohort, demonstrating a novel application for in vivo 129Xe spectroscopy. The next set of experiments measured the red blood cell chemical shift in the lungs of healthy control rats at different fractions of inhaled oxygen. The results showed that the chemical shift increased with decreasing oxygenation. This is the opposite trend to what had been previously reported in human blood and will be important for future experiments that use 129Xe spectroscopy in pre-clinical disease models. Lastly, spectrally-resolved 129Xe imaging of the brain and the potential to image gas transfer across the blood brain barrier was demonstrated. The chemical shift of red blood cells was also measured to have the same dependence on oxygenation in the rat brain as in the lungs. The work presented in this thesis provides a framework for measuring oxygen delivery in rats that can potentially be translated to imaging humans.

Keywords: 129Xe
Brain
Hyperpolarized
MRI
Oxygenation
Rat
Advisor: Santyr, Giles
Kassner, Andrea
Achieving Learning Regulation Support: How a Socially Shared Approach Fits, Functions, and Thrives

Across three studies, the purpose of this dissertation was to explore how socially shared learning regulation (SSLR) “fits” as a suitable solution to the lack of learning regulation support in Ontario, “functions” to support teachers’ professional learning and students’ independence, and best “thrives” among teacher implementers who face a range of constraints. Three different research methodologies were used with the overall goal of providing guidance to educators and researchers regarding the use of socially shared learning regulation as a classroom teaching approach. In Study 1, data gathered from 50 key Ontario Ministry of Education (MOE) documents were analysed to measure the alignment between SSLR and the practices and mandates that are prescribed as guidance for educators in Ontario; considerable “fit” between the MOE publications and the central tenants of SSLR was discovered. Especially within these areas of fit, a lack of pedagogical specificity for educators was both apparent and remarked upon by the documents themselves. These seem as though they could be addressed, at least partly, through the use of SSLR. In Study 2, a qualitative interview method was used to explore the way an SSLR pedagogy may “function” to support teachers’ pedagogical learning, personal learning regulation development, and student independence. A second researcher was heavily involved in the recruiting, interviewing, transcribing, and coding for this study to supply greater objectivity and place the first researcher at an arms-length from a topic in which she had a vested interest. In this study, a wide range of pedagogical learning resulting from teachers’ use of SSLR was revealed, as well as an epistemological shift in the way teachers viewed their students as learners. In Study 3, a mixed methods approach was used to gather descriptive information about the types of enablers and constraints faced by teachers as they attempted to engage in SSLR – a brand new pedagogical approach for most. Survey and short answer data was collected over 3 months and 3 timepoints from 81 kindergarten to Grade 8 teachers who were genuinely dissatisfied by their status quo practices, ready for change, and largely eager to implement the novel teaching approach presented to them. Building on established theories of planned change implementation, the findings of this study indicated a minimal effect of teachers' approval of the intervention on implementation. Rather, specific drivers to the implementation of complex, communal pedagogical interventions included the support of high-status supervisors and peers, while constraints to implementation included fears regarding management of student behavior.

Keywords: executive function
MCII
metacognition
pedaogogy
self-regulated learning
socially shared learning regulation
Advisor: Martinussen, Rhonda
Illegible Subjects: Knowledge and American Modernity, 1898-1985

This dissertation explores the relationship between politics and knowledge as represented by a set of late-nineteenth and mid-twentieth century American writers. The category of knowledge has long been regarded as a site of power and has, consequently, also been a site of contestation. There is a suggestion that if the way the world is understood ramifies through the domains of the political and the social, then efforts must be made to—as Eve Sedgwick puts it—“pluralize and specify” knowledge in order to disentangle it from oppressive agendas. This mode of critical address has a lot of traction in the humanities and is differently exemplified by scholars such as Michel Foucault, Judith Butler, and Sylvia Wynter. I intervene in their conceptions about the relationship between knowledge production and social change by examining a series of American writers who, rather than remaking the normative codes that impose legibility on social and political life, work towards accessing the broad range of political possibilities that exist outside of what is either known or knowable. I begin by surveying the critical field that examines the relationship between knowledge, politics, and everyday life. In particular, the introduction draws upon the pragmatist philosopher William James and his critique of “vicious intellectualism” to develop what I call American society’s legibility imperative and consider how it can be undone. My first chapter demonstrates how the late writing of Henry James militates against modernity’s reduction of all aspects of life to what is profitable and quantifiable by celebrating forms of human subjectivity and relation that are purposeless, unpredictable, and porous. Next, I interrogate how Nella Larsen’s Quicksand suggests that the production of sustaining forms of collective life depends upon the suspension of the coercive demand that subjects exchange their radical opacity for identitarian legibility. My third chapter explores how the essays of James Baldwin contend that the imagining and creation of a better world is predicated upon rethinking the normative value accorded to knowledge in the practice of politics. I conclude with Djuna Barnes’s Nightwood which argues that doing away with knowledge’s priority could potentially lead to the emergence of an authentic, non-hierarchical, and trans-species community.

Advisor: Dolan, Neal
Characterizing the Mechanism of Young Bone Marrow-derived Microglia-like Cells on Restoring Cognitive Function in the Aged Brain and After Ischemic Injury

Neurodegeneration in the aged population is the leading cause of death, disability, and impaired quality of life worldwide. Among the many proposed mechanisms for neurodegenerative diseases, emerging evidence indicate microglial deterioration to be at the center of this. Here, microglia in the aged brain become primed and acquire a pro-inflammatory phenotype marked by increased secretion of inflammatory chemokines and cytokines. This in turn can lead to synaptic pruning, neuronal death, and cognitive impairments. In this work I propose a novel approach to address this important issue: bone marrow (BM) reconstitution with young stem cell antigen-1 (Sca-1)-expressing hematopoietic stem cells (HSCs) for the introduction of healthy blood borne-derived microglia-like cells into the aged brain for attenuation of age- and injury-induced loss of neuronal and cognitive function. My findings reveal that transplanted young HSCs repopulate the aged recipient BM and home to the brain to ultimately give rise to several thousand microglia-like cells in regions of the brain involved in neurogenesis, learning and memory, reward circuitry, and emotional regulation. Multicolor flow cytometry revealed these cells to be distinct from brain-resident microglia, while immunofluorescence staining demonstrated young and old BM-derived microglia-like cells to be positive for markers associated with anti- and pro-inflammatory phenotypes, respectively. These BM-derived microglia-like cells were seen to populate the hippocampus 1- and 3-months post-reconstruction, effectively reversing age- and ischemic injury-induced loss of novel object recognition and spatial memory and learning. The presence of these cells was significantly diminished from the hippocampus 3-months post-reconstitution; however the benefits in behavior, synaptic plasticity, and dendritic spine density in pyramidal neurons persisted. Selective BM-derived microglia-like cell depletion at 1-month post-reconstitution using generated Cx3cr1CreER/+R26iDTR/+ mice revealed the necessity of these cells as there was a loss-of-function on behavioral performance. RNA and protein screening on ex vivo microglia-like cells revealed significant upregulation in brain-derived neurotrophic factor (BDNF) and proteins involved in cytoskeletal remodeling. Blocking BDNF binding in reconstituted animals 1-month post-transplantation using the antagonist, ANA-12, abolished functional improvements and dendritic spine arborization. In summary, I demonstrate the sufficiency and necessity of young, but not old, BM-derived microglia-like cells on restoring cognitive capacity in aged recipients.

Advisor: Li, Ren-Ke