VictorJuiz/thesis huggingface dataset:
Ultra-Diffuse Galaxies and Ultra-compact Dwarfs in the Hubble Frontier Fields

Large low surface brightness galaxies have recently been found to be abundant in nearby galaxy clusters. In this thesis, I investigate these ultra-diffuse galaxies (UDGs) in the six Hubble Frontier Fields galaxy clusters: Abell~2744, MACSJ0416.1-2403, MACSJ0717.5+3745, MACSJ1149.5+2223, Abell~S1063 and Abell~370. These are the most massive (1-3 × 1015~Mo) and distant (0.308 < z < 0.545) systems in which this class of galaxy has yet been discovered. The clusters host an estimated ~200-1400 UDGs inside the virial radius (R200), consistent with the UDG abundance halo-mass relation found in the local universe, and suggests that UDGs may be formed in clusters. Within each cluster, however, I find that UDGs are not- evenly distributed. Instead their projected spatial distributions are lopsided, and they are deficient in the regions of highest mass density as traced by gravitational lensing. While the deficiency of UDGs in central regions is not surprising, the lopsidedness is puzzling. The UDGs, and their lopsided spatial distributions, may be associated with known substructures late in their infall into the clusters, meaning that I find evidence both for formation of UDGs in clusters and for UDGs falling into clusters. Also included is a catalog of UDGs in the Frontier Fields. I also investigate the ultra-compact dwarfs (UCDs) residing in the clusters, and find the spatial distributions of UDGs and UCDs appear anti-correlated. Around 15% of UDGs exhibit either compact nuclei or nearby point sources. Taken together, these observations provide additional evidence for a picture in which at least some UDGs are destroyed in dense cluster environments and leave behind a residue of UCDs.

Keywords: dwarf galaxies
galaxy clusters
low-surface-brightness galaxies
ultra-compact dwarfs
ultra-diffuse galaxies
Advisor: Abraham, Roberto
Music by the Ducat: Giuliani's Guitar and Vienna's Musical Markets, 1806-1819

Amidst ambivalent attitudes held toward the guitar, Italian-born guitar virtuoso Mauro Giuliani (1781-1829) composed and performed in Vienna from 1806 to1819. Giuliani’s time in the city was punctuated by his participation in the market for goods related to the Congress of Vienna. He entered this market by gearing his performances and publications towards representing the Congress’s mandate of cooperation and conversation, as well as the recent interest in Austrian folk songs alongside patriotic sentiments for an emerging Austrian state. Giuliani’s solo guitar performances were defined by his unique ability to overcome what critics regarded as the guitar’s seemingly unsurmountable deficiencies. His active participation in the virtuoso concert culture of Vienna—a market that was removed from a growing “serious” concert culture—was defined by his increasing involvement in the commercially-driven subscription concert. Underlying Giuliani’s participation in the Congress of Vienna and the popular virtuoso concert was his interest in the burgeoning folk music movement. Related to Austrian patriotic sentiments, Giuliani’s folk-inspired Ländler and variation sets reveal his preoccupation with a more quotation-based approach to folk song composition, an approach that—while attractive in terms of print music sales—jeopardized the longevity of his folk-inspired works by obscuring his authorial ingenuity. The early nineteenth century is regarded by guitar scholars as the “Golden Age of the Guitar,” and Giuliani is often positioned as one of the foremost contributors to the development of classical guitar repertoire during this time. However, I argue that Giuliani’s approach to guitar composition and performance reveals not a desire to cultivate a solo classical guitar repertoire, but a concerted effort to present the guitar, and by extension, himself, as a commodity for Viennese markets associated with the Congress of Vienna celebrations, the lucrative virtuoso concert, and the burgeoning folk music movement. Underlying each of these markets was a demand for public and private performances, as well as a desire for printed music. The result of Giuliani’s efforts were performances and works that, while meant for consumption by the wider public, engage with the intimate, easily digestible, and sociable aspects of Vienna’s musical culture.

Keywords: Classical Guitar
Congress of Vienna
Folk Music
Mauro Giuliani
Nineteenth-Century Vienna
Virtuosity
Advisor: Lee, Sherry D
Fabrication of Carbon-based Nanocomposite Materials for Energy Storage Processes

Our society’s development depends on the way we use, store, and transform the energy. Currently, we have multiple sources of clean energy to cover the demand of a growing population. However, a big gap remains in the technology to efficiently store the energy that is not being consumed. The purpose of this thesis is to explore carbon-based composite materials to promote the development of new systems for the efficient conversion, use, and storage of energy: first, at small-scale storage (batteries) and second, at large-scale storage (power to gas). In both cases, different carbon allotropes and functionalization methods were considered. The first half of the thesis describes materials and methods to improve the air cathode in Zn-air batteries. These batteries are considered promising energy storage devices because of the numerous advantages such as high energy density, low-cost and abundance of Zn, environmental friendliness, and safety. The first study is focused on developing a double layer membrane fabricated with thermoplastic polyurethane, carbon nanotubes, and activated carbon membrane to improve the oxygen diffusivity and to prevent electrolyte leakage. For the second study, we developed a bifunctional electrocatalyst to promote the oxygen reactions in Zn-air batteries and achieve an electrically rechargeable configuration. The electrocatalyst was fabricated with Co3O4 particles attached to a functionalized carbon support. The second half of the thesis is focused on the catalytic methanation of CO. This process allows the reduction of the main greenhouse gas, through the power-to-gas technology. Renewable energy can be used to power a reactor where the CO/CO2 is reduced to methane, which can be transported and stored in current systems. We considered Ni-based catalysts and carbon-based supports with the purpose of improving the CO conversion, the selectivity to CH4, and the catalyst stability. This study first compares Ni supported on AC and Ni3Sn supported on AC to determine the effectiveness of Sn as a carbon fiber suppressor. In a second step, the study describes the fabrication method and catalyst performance of a core-shell structure using silica spheres grown on SWCNTs coated with the catalysts Ni3Sn and FeNi3 to improve the thermal stability and catalyst activity.

Keywords: Carbon-based composite materials
Energy storage Processes
Methanation of CO
Zn-air batteries
Advisor: Naguib, Hani
Kesler, Olivera
Dual Roles of Nerve-Derived Precursor Cells During Adult Mammalian Tissue Regeneration

Accumulating evidence suggests that endogenous tissue-resident precursors and stem cells play an important role in mediating the repair and regeneration of various adult tissues. Peripheral nerve innervation, found throughout all organs, is known to be an essential component of this regenerative injury response across various tissues and species, but through predominantly ill-defined mechanisms. Thus, here we utilized lineage tracing strategies combined with other approaches in order to ask how peripheral nerve-derived precursor cells might contribute towards mammalian tissue repair and regeneration. Using the adult mouse digit tip as a model to study multi-tissue regeneration, we first showed that following amputation of the distal digit, neural crest-derived Sox2-positive Schwann cells associated with nerves dedifferentiate to a precursor-like state and secrete growth factors including PDGF-AA and oncostatin M which stimulate the proliferation of surrounding mesenchymal cells. While normal regeneration was perturbed following surgical denervation or targeted genetic ablation of Sox2-positive Schwann cells, we showed that it could be largely rescued by transplantation of exogenous Schwann cells or their secreted ligands into denervated digits.

Keywords: Growth factors
Mesenchymal precursor cells
Peripheral nerves
Schwann cells
Tissue regeneration
Wound healing
Advisor: Miller, Freda D
Methodological Considerations and Findings of a Vowel Perturbation Study in Typically Developing Children

Background: Auditory feedback enables the speech production system to compensatively correct for articulatory errors and to adaptively calibrate feedforward commands. Less is known about how these feedback control processes develop. Development can be probed by comparing how younger and older children compensate and adapt for experimentally-perturbed vowels in their auditory feedback. Aims: The aims of this work were to evaluate methods for real-time vowel estimation and tracking; to devise appropriate methods for meaningful analysis of data; and to apply those methods in a vowel perturbation study with children aged 4 to 9 years old, towards furthering an understanding of developmental speech motor control. Evaluation of vowel estimation and tracking: Audapter vowel perturbation software was tested on real and synthetic speech samples. The software was evaluated to be appropriate for use in children aged 4 to 9, within error margins of 60 Hz for F1 and 180 Hz for F2. Development of analyses: Circular statistical methods were demonstrated as a means to gain insight from directional vowel changes in F1-F2 space during compensation and adaptation; these methods supplement existing approaches to analyze changes in F1 and F2 separately. Vowel perturbation study: Children compensated and adapted for vowel perturbation, but younger and older children accomplished this in different ways. While older children compensated more directly to oppose the perturbation, younger children altered their vowels less directly, indicating that the role of auditory feedback within the speech system changes during development. Adaptation to perturbation was more variable than compensation in both groups. Contributions: This work contributes performance metrics for Audapter research software in children. The application of descriptive circular statistics to analyze vowel perturbation data was demonstrated. Preliminary evidence indicates that there are developmental differences in the manner in which children respond to vowel perturbation. There may be developmental differences in the manner in which sensory information is integrated (i.e. auditory with somatosensory) that could underlie these findings. Future research, using the circular analytical methods described in this dissertation, is needed to investigate this possibility, and to generate additional evidence towards furthering the understanding of auditory feedback integration in developing speech motor control.

Keywords: Auditory feedback perturbation
Speech development
Speech motor control
Vowel formants
Advisor: Beal, Deryk S
Studying Abroad: An Anti-Colonial Inquiry

Study abroad has the potential to provide a valuable learning opportunity, provided students are supported throughout their experience to critically think and challenge the reification of knowledge hierarchies that are endemic of a colonial education system. This dissertation employs an anti-colonial discursive framework to explore the supports that exist in Ontario’s college system for domestic students engaging in a study abroad experience. Representatives from Ontario’s colleges were interviewed to gain insights into what pedagogical strategies were being used to support domestic students’ critical thinking pre-departure, while abroad, and upon return. Challenges to the implementation of a pedagogical framework, as well as participants’ views on best practices, were also explored. Thematic analysis was used to analyze the data. Findings indicate that the export commodity and human capital development models of internationalization inform the availability of study abroad support for domestic students. Despite the existence of some support, participants referenced a lack of a well-established framework to guide the experience. Pre-departure supports emphasized culture and safety, whereas, while abroad and upon return, reflection was a frequently used pedagogy. Participants emphasized the need for greater pedagogical supports throughout the study abroad experience. There is an opportunity to further develop the framework for pedagogical strategies, as participants reported a time of change at their respective institutions, with the formalization of processes and the centralization of resources underway. Recommendations are provided.

Keywords: study abroad
Advisor: Dei, George
Effects of Motivation for Prosocial Spending on Subsequent Positive Affect

The present research compared the effects of empathy, moral elevation and a control condition as motivations for charitable donations on subsequent feelings of positive affect. Empathy and moral elevation have strong emotional aspects that provide the impetus for prosocial behavior. Empathy is defined as an other-oriented and congruent affective reaction that is concerned with the perceived well-being of another person (Batson, Ahmad, Lishner, 2009), while moral elevation is the warm, uplifting feeling people experience after witnessing moral beauty (Haidt, 2000). Empathy often induces negative feelings from seeing others in distress, while moral elevation often induces positive emotions. Thus, the initial difference in affective valence may have different effects on the positive affect experienced after acting prosocially. Furthermore, a number of personal characteristics are known to influence positive affect after prosocial behavior, such as personal values, internalized prosocial motivation and the satisfaction of basic psychological needs, namely autonomy, relatedness and competence. Therefore, the present study compared the effects of empathy and moral elevation, as well as a control condition, on individuals’ donations to charity and their subsequent positive affect while controlling for personal characteristics. Participants were 249 students from an introductory psychology class at the University of Toronto. The results suggested that participants in both the empathy and moral elevation conditions experienced significant decreases in positive affect following the induction of motivations, but that donating only helped restore positive affect to baseline measures in the moral elevation condition. Donating to charity was unable to restore participants to baseline measures in the empathy condition. The results also indicated that needs for competence and relatedness, internalized prosocial motivation and emotion regulation positively predicted positive affect after donation, while prosocial and pro-self values both negatively predicted positive affect after donation. As well, the association between affective empathy and positive affect after donating was negative for participants in the empathy condition, but positive for participants in the moral elevation condition. Similar differences by condition were found for internalized prosocial motivation and positive affect after donating. The theoretical and practical implications are discussed.

Keywords: empathy
moral elevation
motivation
positive affect
Advisor: Grusec, Joan E
On Learning Models of Appearance for Robust Long-term Visual Navigation

Simultaneous localization and mapping (SLAM) is a class of techniques that allow robots to navigate unknown environments using onboard sensors. With inexpensive commercial cameras as the primary sensor, visual SLAM has become an important and widely used approach to enabling mobile robot autonomy. However, traditional visual SLAM algorithms use only a fraction of the information available from conventional cameras: in addition to the basic geometric cues typically used in visual SLAM, colour images encode information about the camera itself, environmental illumination, surface materials, vehicle motion, and other factors influencing the image formation process. Moreover, visual localization performance degrades quickly in long-term deployments due to environmental appearance changes caused by lighting, weather, or seasonal effects. This is especially problematic when continuous metric localization is required to drive vision-in-the-loop systems such as autonomous route following. This thesis explores several novel approaches to exploiting additional information from cameras to improve the accuracy and reliability of metric visual SLAM algorithms in short- and long-term deployments. First, we develop a technique for reducing drift error in visual odometry (VO) by estimating the position of a known light source such as the sun using indirect illumination cues available from existing image streams. We build and evaluate hand-engineered and learned models for single-image sun detection and achieve significant reductions in drift error over 30~km of driving in urban and planetary analogue environments. Second, we explore deep image-to-image translation as a means of improving metric visual localization under time-varying illumination. Using images captured under different illumination conditions in a common environment, we demonstrate that localization accuracy and reliability can be substantially improved by learning a many-to-one mapping to a user-selected canonical appearance condition. Finally, we develop a self-supervised method for learning a canonical appearance optimized for high-quality localization. By defining a differentiable surrogate loss function related to the performance of a non-differentiable localization pipeline, we train an optimal RGB-to-grayscale mapping for a given environment, sensor, and pipeline. Using synthetic and real-world long-term vision datasets, we demonstrate significant improvements in localization performance compared to standard grayscale images, enabling continuous metric localization over day-night cycles using a single mapping experience.

Keywords: Appearance estimation
Computer vision
Deep learning
Long-term autonomy
Mobile robotics
State estimation
Advisor: Kelly, Jonathan S
Technologically Yours: How New Technologies affect Psychological Distance

Consumers have at their disposal an ever-increasing variety of new technologies with which to receive and communicate information. Prior research has examined why individuals choose one source of information over another, but not how the source of information influences judgments about the information it provides. The present dissertation examines how judgments of psychological distance are affected by the source or modality from which they are received, focusing on communication media (text messages versus emails) and algorithmic (versus human) prediction. Essay 1 investigates whether the prominent norms attached to different communication modalities contain information in and of themselves. I consider this question through the lens of text messages and emails, hypothesized to confer different normative information about urgency. Text messages (versus emails) — or any communication inferred by receivers to have been sent with greater urgency — cause the content of those messages to seem, in the eyes of receivers, closer in time (Study 1), closer in space (Study 2), and more likely to occur (Study 3). Moderation and mediation analyses confirm the role of urgency underlying the relationship between modality and distance. I provide evidence for these effects in a series of lab studies together with a field study in which real text messages and emails impact not only inferred distance but also a behavior deriving therefrom. Essay 2 investigates how judgments of psychological distance across a range of predictions, forecasts, and recommendations, are affected by the source of those predictions. Specifically, I examine differences in the judgment of these distances when predictions are provided by human or algorithmic sources. I find that predictions are judged differently depending on their source. Participants judged machine recommendations to be spatially and temporally closer (Studies 1 and 2) but felt socially closer to and perceived increased likelihood in human recommendations (Studies 3 and 4). I find that these differences are mediated by the perceived expertise of the source and perceived certainty of the prediction (Studies 3, 4, and 5). Theoretical and practical implications highlight the importance, for both researchers and practitioners, of understanding how new technologies affect the interpretation of information.

Advisor: Maglio, Sam J
Mapping Genetic Interactions for Rare Disease-Associated Genes

Over 7,000 rare diseases have been identified in the human population that, in aggregate, affect over 400 million people worldwide. The majority of rare diseases that have been identified are genetic in origin. However, a key challenge in developing therapies is that the functions of many rare disease-associated genes are poorly understood and consequently, their role in disease pathogenesis. There is strong appreciation that genes do not act in isolation and many disease phenotypes may arise from complex genetic interactions (GIs). Systematic mapping of GIs offers a wealth of information about gene function and advancements in gene-editing technology, such as clustered regularly interspaced short palindromic repeats (CRISPR), allows for GI mapping in human cells. In this thesis, I describe how lentiviral-based genome-wide pooled CRISPR/Cas9 screens offer insight into the function of rare disease-associated genes including NGLY1 and the genes encoding the complement regulatory proteins (CRPs): CD46, CD55, and CD59. Autosomal recessive mutations in NGLY1 give rise to NGLY1-deficiency, a congenital disorder of deglycosylation. How the loss of NGLY1 function contributes to disease pathogenesis is poorly understood. The CRPs are key inhibitors of the complement cascade and their impaired function contributes to a wide range of common and rare diseases. Similar to NGLY1, the functions of the CRPs independent of complement-regulation and roles in disease have not been explored using functional genomics approaches. To further our functional understanding of NGLY1 and the genes encoding the CRPs, I performed pooled genome-wide CRISPR/Cas9 screens to identify GIs, and uncovered a novel genetic relationship between the CRPs and the NGLY1 pathway involving genes in the secretory pathway that may coordinate different aspects of intracellular cholesterol trafficking. My work demonstrates the utility in mapping GIs in order to reveal functional relationships with rare disease genes, offering critical insight into the genetic underpinnings of NGLY1-deficiency and complement-independent functions of the CRPs. As the functions of many rare disease-associated genes are poorly characterized, mapping genetic interactions in co-isogenic human cell lines using genome-wide CRISPR screening approaches offers a powerful framework that may be exploited to gain insight into gene function and direct future therapeutic efforts.

Advisor: Moffat, Jason