VictorJuiz/thesis huggingface dataset:
Magneto-centrifugal Wind with Applications to Astrophysical Accretion Disks
Keywords: Accretion Disk
Active Galactic Nuclei
Cosmic Ray
Magneto-centrifugal Wind
MHD
Starburst Galaxy

We calculate the structure of radially self-similar magneto-centrifugal winds with a wide range of magnetic flux distribution, mass loading, and injection speed at the base of the wind. A variety of wind structures is obtained, including winds driven by magneto-centrifugal and magnetic pressure gradient forces. The critical magnetic tilt needed to achieve an Alfven transition is sensitive to the wind properties, especially the magnetic flux distribution and injection speed, and generally exceeds the 30 degrees minimum for a magneto-centrifugal slingshot. A connection between magnetic tilt and minimization of the specific wind energy is conjectured. The least tilted wind solution is shown to approach the potential solution at low mass loading. Gaseous disks in star-forming galaxies and active galactic nuclei may contain dynamically important magnetic fields and significant flux of cosmic rays. In contrast with radiation-pressure dominated disks, a much weaker energy input in cosmic rays is required to support the disk against vertical gravity, and to drive a magneto-centrifugal outflow. Taking into account cosmic ray ionization, streaming, injection from massive stars and energy losses, we calculate the transition from a hydrostatic disk to an outflowing wind. The solutions are constrained by the slow-magnetosonic critical point associated with cosmic ray streaming; the wind is initially driven by the cosmic ray pressure gradient rather than the magneto-centrifugal force, with the magneto-centrifugal force dominating at larger heights above the disk. The specific example that is explored in quantitative detail involves a near Eddington accretion flow onto a supermassive black hole, at a distance from the hole where a viscous disk tends to be gravitationally unstable. We find that the disk magnetization is around unity, which optimally fixes the fraction of the radial mass flow returned to the wind at order 0.01. Radial scalings in a constant Q disk are worked out.
Origami-inspired Mechanical Metamaterials
Keywords: 3D printing
Compression testing
Fracture mechanics
Impact testing
Origami-inspired materials

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.
Infinite Shoreline for Orchestra
Keywords: Coastline Paradox
Fractals
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”
Blind Spots in Personality Traits and Interpersonal Problems: The Roles of Narcissism and Self-esteem
Keywords: Narcissism
Self-esteem
Self-knowledge

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.
The Work of Getting Better: An Institutional Ethnography of an Early Psychosis Intervention Clinic
Keywords: Canada
early psychosis intervention
institutional ethnography
medication adherence
recovery
trust

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.
Hyperpolarized 129Xe Magnetic Resonance Spectroscopy and Imaging of Blood Oxygenation and Gas Exchange in Rats
Keywords: 129Xe
Brain
Hyperpolarized
MRI
Oxygenation
Rat

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.
Achieving Learning Regulation Support: How a Socially Shared Approach Fits, Functions, and Thrives
Keywords: executive function
MCII
metacognition
pedaogogy
self-regulated learning
socially shared learning regulation

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.
Mid-infrared Photophysics of Boron Nitride Nanotubes
Keywords: Boron Nitride
Hyperbolic
Nanotube
Photophysics
Polariton
s-SNOM

Boron nitride nanotubes (BNNTs) represent ideal substrates for first principles understanding of phonon polaritons (PhPs) due to their one-dimensional nature, tunable sizes and ready synthetic techniques. Herein, we present work towards a comprehensive understanding of their photophysical properties within the Upper Reststrahlhan Band (~1360 – 1530 cm-1). Synthetic methods towards chemical vapor deposition (CVD) growth of BNNTs and hierarchical 2D BNNT structures are presented. The ability to characterize BNNTs using a novel broadband infrared source is addressed as well as computational modeling for the reflection of a polariton wave at a strong, internal dielectric barrier. Work showing the modification of the dielectric function and subsequent polariton dispersion by the internal void within BNNTs is demonstrated, culminating in understanding of the large geometry-mediated scattering enhancement at the ε = −1 crossing of the dielectric function. Conditions that result in strongly resonant PhPs are examined in tubes which support Fabry-Perot behavior. Finally, next steps are discussed in the field of BNNT polaritonics including perspectives on future devices.
Les Professionnelles et Les Professionnels Formes a L'etranger et Leur Insertion au Travail dans le Contexte Francophone Minoritaire en Ontario: Le Cas des Enseignantes et des Enseignants Originaires de L'Afrique Subsaharienne
Keywords: diversité
Éducation
francophonie
migration
minoritaire
professionnels formés à l'étranger

La présente étude vise un double objectif, d’une part, appréhender la réalité de l’insertion professionnelle des Africaines et des Africains francophones en milieu minoritaire au Canada et d’autre part connaitre leur vécu dans les écoles de langue française de l’Ontario. Devant les enjeux comme ceux liés à l’accès à l’emploi, ces professionnelles et professionnels imaginent différentes stratégies, incluant celle de devenir enseignantes ou enseignants, ce qui m’a poussée à me poser les questions suivantes : Premièrement, comment les professionnelles et les professionnels originaires de l’Afrique subsaharienne formés à l’étranger dans un domaine autre que l’éducation vivent-elles ou vivent-ils leur réorientation vers la profession enseignante une fois embauchés dans le système d’éducation de langue française de l’Ontario? Deuxièmement, à partir de leurs différentes expériences sociales et professionnelles précédentes comment ces enseignantes et ces enseignants se perçoivent-elles et se perçoivent-ils après leur passage à une autre profession? Troisièmement, cette nouvelle expérience peut-elle être considérée comme une reconstruction potentielle de leur identité professionnelle dans leur trajectoire migratoire? Et, enfin, en quoi leur participation à la communauté de pratique les lie-t-elle à une carrière en enseignement? Cette stratégie nous semble attrayante en raison du contexte actuel de la pénurie d’enseignantes et d’enseignants dans les écoles de langue française de l’Ontario. La présente recherche s’articule autour de deux théories clés, à savoir l’insertion sous l’angle de la socialisation professionnelle et la construction des identités sociales et professionnelles (Dubar, 1991 cité dans Trottier, 2001, p 9) ainsi que celle de la communauté de pratique (Wenger, 2005). Pour bien appréhender la manière dont les identités sociales se perpétuent et changent, il importe de comprendre par quel mécanisme de socialisation elles se constituent et se recomposent. À cette fin, j’ai analysé les parcours migratoires diversifiés qui ont amené ces personnes à une insertion professionnelle dans l’enseignement. Mais, aussi, j’ai abordé la manière dont elles ont construit leur identité professionnelle comme produit d’une histoire à la fois singulière et collective. Et cela, dans trois communautés de pratique différentes. Cette étude m’a donné l’occasion de comprendre les parcours variés d’insertion professionnelle des immigrantes et immigrants ainsi que les stratégies utilisées.
Vibrant Stone: Ground Stone Celt Biographies Among the Ancestral and Historic Wendat in Southern Ontario from the 14th to mid-17th Centuries
Keywords: 14th to mid-17th century
American Northeast
Chaîne opératoire
Ground stone celts
Southern Ontario
Wendat

Ground stone celts are an understudied artifact category in Ontario archaeology despite their essential contribution to the intensification of sedentarism and horticulture in northern Iroquoian communities. This dissertation studies 2660 ground stone celt artifacts – including blanks, roughouts, debitage, complete celts, recycled and unrecycled celt fragments — from 20 legacy collections of ancestral and historic Wendat sites dating between the 14th and mid-17th centuries in southern Ontario to better understand their comprehensive roles in northern Iroquoian lifeways before and at the onset of European contact.I integrate the chaîne opératoire and New Materialism to reconstruct ground stone celt biographies from a relational perspective. Viewing stones as a vibrant agent, my investigation begins with geological histories, which preshaped celts at the source and affected morphological changes in later stages of their biographies. Metamorphic stones predominantly used to make the documented celts originate from the Canadian Shield, a powerful and geologically complex landscape with a long history of human and non-human relations. Regional longue durée shows that Indigenous peoples made and used ground stone celts since the Middle Archaic period. Thousands of years of relations to stones and the landscape carried through the biographies of ancestral and historic ground stone celts during the Late Woodland period. Ethnohistoric and ethnographic accounts indicate that ground stone celts came to mediate transformative relations between the Wendat and various non-human beings including trees, soil, animals, and plants. The chaînes opératoires of the documented celts reveal that stone selection processes and celt morphologies resulted from reciprocal and co-creative engagements assembling humans, non-humans, and historical contexts, which preserved and transformed geologically formed surfaces, morphologies, and functions. Throughout changing social, economic, political, and territorial contexts of the American Northeast between ca. 1300 and 1650 CE, Wendat communities reoriented procurement strategies while maintaining shared ways of relating to ground stone celt properties and biographies. The ever-changing ground stone celts thus escape typological classification, and cannot be used as cultural, temporal, or functional markers. Their persistence alongside copper and iron cutting tools of European origin on early to mid-17th-century sites further indicates the strong connections that the Wendat developed with these vibrant stones.