VictorJuiz/thesis huggingface dataset:
Signal Processing and Instrument Characterizationon a Large-N Radio Interferometer

The CHIME radio interferometer telescope was designed with the purpose of studying dark energy during an era of accelerated expansion. It will conduct a survey of large scale structure to sample the matter density field in HI emission and measure the time evolution of the dark energy equation of state, w. CHIME is a large-N telescope and features the largest GPU correlator in radio astronomy. Here I present my contributions to the CHIME project, which took place during my graduate career, between 2015-2022. The GPU array cluster is supported by an enterprise scale software backend that I helped design to be portable and extensible by an object-oriented code infrastructure. The CHIME backend, kotekan, is built for multi-tiered task allocation across the GPU cluster that includes support tasks such as RFI excision, in addition to several operational modes including beamforming. Extensions to the architecture are designed for new science objectives and compliment the cosmology functionality to include new capabilities for FRB surveys and pulsar timing. The GPU management infrastructure I wrote and beamforming code I optimized are described here and directly impacted these objectives. Calibration of the system is performed by precisely measuring the response of the instrument. This is accomplished by either setting configurations in advance of observation cycles or by manipulating the correlated visibilities offline. Statistical analysis of the data using conventional methods such as principal component analysis are applied to test the quality of the data by estimating the redundancy of baselines that are averaged to improve signal-to-noise. The work toward optimal calibration is an evolving process for greater fundamental understanding of the system. The achieved performance of the existing calibration of the telescope can be evaluated through application in a scientific study. The study presented here is of the Cygnus Loop and a spatial spectral index variation mapping across the surface of the feature. The study incorporated every calibration developed by the collaboration and addressed every systematic present in the system. The calibrator 3C286 was selected to calibrate the spectral flux density and several beam models were applied to calibrate the spectral response.

Keywords: CHIME
cosmology
cygnus loop
dark energy
radio interferometer
Advisor: vanderlinde, keith
Development of Vapor-phase Deposited Perovskite for Light-emitting Diodes

Light-emitting diodes (LEDs) are steadily becoming the new standard for luminescent display devices because of their energy efficiency and relatively low cost, and the purity of the light they emit. Perovskite materials have attracted tremendous research interests in recent years for LEDs and photovoltaic applications due to their simple synthesis and record-breaking performances. To this day, most perovskite research focuses on solution-based syntheses. There is a limited number of reports on fabricating perovskite LEDs by vapor-phase deposition (VPD), a process in vacuum that lowers the risk of contaminants and offers much better control over the thickness of films. This method can also be easily scaled up for commercial production and is currently used for publicly available LEDs/OLEDs. The class of perovskite at the center of this research is the caesium lead halide family (CsPbX3), which were found to have high colour purity, an intrinsically high photoluminescence yield and a better stability, making them strong candidates for light-emitting applications. The goal of this project is to gain a proper understanding of the material and optical behaviour of these perovskites fabricated through VPD. The underlayer (hole transport layer in the LED structure) onto which the perovskite is grown is found to have a significant impact on the film’s uniformity and can limit the reaction between the perovskite precursors CsBr and PbBr2. Hole transport layers with higher glass transition temperatures (Tg) are found to be critical to facilitate growth of crystalline perovskites, improving the colour purity. Passivation studies show that CsPbBr3 films, when coated with a thin LiBr overlayer, demonstrate an extraordinary mass transport at room temperature with self-assembly into well-defined islands. LiBr also passivates nonradiative defects and significantly boosts the luminescence performance of CsPbBr3 as single films and in LED devices. This thin film self-assembly phenomenon is also observed with CsPbCl3 and CsPbI3 compounds with varying nanostructures. The unique role of LiBr in facilitating perovskite thin film recrystallization due to increased moisture attraction is demonstrated through Density Functional Theory simulations.

Keywords: Light-emitting Diode
Passivation
Perovskite
Self-assembly
Thin films
Vapor-Deposited
Advisor: Lu, Zheng-Hong
The Lived Experience of Street-involved and Homeless Youth who have Eating Struggles while Living in Situations of Food Insecurity

Eating struggles continue to be predominantly conceptualized as a white, middle-to-upper class, cis-gender, female youth disorder, evident by physical emaciation. This is despite the rise of literature evidencing the existence of eating struggles among individuals of diverse backgrounds including those living in situations of poverty, food insecurity and homelessness. Street-involved and homeless youth (SIHY) often endure extreme forms of food insecurity that significantly impact their relationship with food and their body. Yet, SIHY are significantly underrepresented within the existing eating disorder and food insecurity literature. This thesis aimed to address this gap by exploring the lived experiences of SIHY who have eating struggles while living in situations of food insecurity; and to explore how SIHY perceive social services in relation to their eating struggles. A Heideggerian hermeneutic phenomenological approach was used to investigate how SIHY with eating struggles interpret and negotiate with their experiences of food insecurity and other oppressive living conditions. This study was conducted at a local SIHY resource centre in Ontario and included 11 participants. The participants were asked to partake in three interview sessions and one body map arts-based activity. The findings of this thesis (1) dismantles misconceptions surrounding SIHY who have eating struggles; (2) expands our understanding of trauma, revealing the multifaceted and interlocking forms of systemic (e.g., food insecurity) and relational traumas (e.g., intimate partner violence) that underlie SIHY’s eating struggles; (3) reveals the deeper purpose of eating struggles as an embodied negotiation and response; and (4) builds knowledge from SIHY’s recommendations for social service provision including conceptualizing healing as not only an inner process but one of which requires change and healing of our world.

Keywords: Body Image
Critical Feminism
Eating Disorders
Food Insecurity
Homeless Youth
Homelessness
Advisor: Lee, Eunjung
Dying to Stay Alive in Residency and Beyond: A Critical Discourse Analysis of ‘Burnout’

In 1974, Dr. Herbert Freudenberger ‘coined’ the term ‘burnout’. With the creation of the Maslach Burnout Inventory in 1984, ‘burnout’ went from a term used in pop psychology to a highly studied phenomenon of academic interest in the helping professions, including medicine. Exponential growth in the study of ‘burnout’, culminated in its adoption into the International Classification of Diseases (ICD)-11 in 2022. Yet, despite awareness of this issue, and the many efforts aimed at addressing ‘burnout’ in physicians, the rates of ‘burnout’ continue to rise. Why does ‘burnout’ persist in medicine despite efforts to ameliorate it? In this thesis, a Foucauldian discourse analysis was used to investigate this question, specifically examining the socializing period of post-graduate medical education (PGME). The purpose of this thesis was to identify different discourses that legitimate or function to mobilize the use of the word ‘burnout’ in PGME. The archive from which the discourses were constructed included 10 review articles, over 500 academic articles, numerous policy documents, autobiographies, videos, documentaries, materials from conferences and discussions in forums including Reddit. This thesis identified three discourses of ‘burnout’: illness, occupational stress and existentialism. Each discourse was associated with statements of truth, signs and signifiers, roles that individuals play within the discourse and different institutions that gained visibility as a result of differing discourses. Finally, the analysis of these discourses revealed socio-historical dimensions of their occurrence, including undefined medicalization, neo-liberal capitalism and existentialism.

Keywords: burnout
discourse analysis
hidden curriculum
medical education
residency
wellness
Advisor: Hodges, Brian B.H.
Leviathans, Act I: big and small

Leviathans, Act I: big and small is the 20-minute first act of a monodrama for baritone, orchestra, and electronics. The first act of this dramatic work includes an overture and four scenes and depicts a world where the seas have risen above the earth, leaving only those aboard ships alive. The narrative situates an exploration of trauma within a post-apocalyptic future, creating fragmentation of self-reflection and musical material. The music in this piece contextualizes human perspective within wild nature. To achieve this, the musical seed material of this work is derived from the sea shanty known as either ‘A Drop of Nelson’s Blood’ or ‘Roll the Old Chariot Along’. The shanty’s chorus seems to originate from a hymn from the 1800s. This sea shanty is particularly interesting as it has evolved drastically, and is still performed in various versions today. I studied an early 1920s wax cylinder recording of an old sailor, where the tune is in a major mode, primarily using stepwise melodic motion. More recent versions, like those made by Fisherman’s Friends and David Coffin, substitute different verses, and use either a minor mode or a mixture of minor and major. In depicting a post-apocalyptic future, I leaned into this concept of evolving folk culture by creating an altered version of the sea shanty to represent that world. The shanty tune informs both melodic and harmonic content in the orchestra, while existing through the electronics as field recordings, contextual sound (i.e. the crew upstairs singing) and distorted material in processed soundscapes. The live electronics, which affect only the singer, serve to further exemplify the subjective perspective of Mara, our lead character, through the effects of reverb, delay and distortion. All of this human created material (i.e. the sea shanty) is filtered through ocean wave motifs and compressed into whale calls, reframing humanity as part of the sea’s wildness.

Keywords: Composition
Electronics
Monodrama
Opera
Orchestra
Voice
Advisor: Kulesha, Gary
Newsome, Gregory
Carbon Dynamics in Freshwater Marshes and Implications for Wetland Conservation and Restoration

Wetland conservation and restoration are at the forefront of natural climate solutions for mitigating the climate crisis by storing carbon in soils. However, carbon accumulation in temperate freshwater marsh soils, and how environmental change and restoration affect carbon burial and preservation in these contexts, remain poorly constrained. In this dissertation, I use paleoecological and geochemical analyses to quantify rates of carbon accumulation and carbon masses of undrained and restored mineral-based freshwater marsh soils, and assess how these are affected by environmental change, including climatic events, land use and restoration, and in-situ processes. I demonstrate that rates of carbon accumulation in undrained freshwater marshes are under certain circumstances high and comparable to those measured in temperate peatlands and salt marshes. Assessments of organic matter quality using programmed pyrolysis and carbon to nitrogen ratios show that short-term rates over decadal time scales are particularly high due to labile organic fractions which degrade and consequently dampen long-term rates of organic carbon accumulation. Using a marsh core spanning ~6,000 years, I show that large inundation events and lake highstands enhance long-term burial and preservation of organic carbon in marsh soils. I also examine diatom assemblages in this paleorecord to show that ecological communities in freshwater marshes have undergone major shifts following European settlement in tandem with land use pressures in the temperate region including hydrological alteration, invasive species, sedimentation and eutrophication. Nonetheless, conservation and protection of undrained freshwater marshes should be given high priority because they can stabilize several meters of soil carbon stocks, which take decades to centuries to recover through restoration. A comparison of soil properties in restored and reference marshes in the same watersheds shows that sites with impermeable substrates, low-lying terrain and connectivity to a larger network of waterbodies or wetland ecosystems have greater soil carbon preservation and should be prioritized where restoration is necessary. I demonstrate the value of using paleoecological data to assess wetland habitat conditions and carbon accumulation before and after European settlement when devising wetland conservation and restoration measures as natural climate solutions. My dissertation also highlights how well-defined time scales are critical when measuring the mitigation potential of undrained and restored freshwater marshes.

Advisor: Finkelstein, Sarah A
The Economics of Social Capital: An Analysis of the Factors that Affect Individual Social Capital Investment and Accumulation

Introduction: Although there is a large literature examining the effects of social capital on health, the literature examining the factors affecting investment in and accumulation of social capital is less developed, especially in the economics literature. Therefore, this dissertation examined the effects of three different sets of factors on adult social capital: 1) time preferences, risk preferences and survival expectations; 2) childhood mental and physical health; 3) genetic endowments (i.e., polygenic score) for education. Methods: This dissertation used the National Longitudinal Study of Adolescent to Adult Health, a cohort of American adolescents recruited in 1994-95 (N=20,745) and followed up in 2001-02 (Wave 3: 15,197), 2008 (Wave 4 N=15,701), 2016-18 (Wave 5 N=12,300). Siblings were oversampled (Wave 1: 1,251 groups). Polygenic scores were available for 80% of Wave 4 respondents in the Genome-Wide Association Study sub-sample. Social capital investments were defined as Waves 3-5 volunteering, religious service attendance, and Waves 3-4 team sports participation, while social capital stock was defined as Wave 4 number of friends, social isolation, and Wave 5 available social support. Results: In individual fixed effects models, we found that time preferences had negative effects while risk preferences had positive effects on social capital investments. Similar associations were found with cross-sectional stock measures. Survival expectations were only associated with stock measures of social capital. In sibling fixed effects models, child self-rated health had a positive effect on team sports participation, social support and decreased social isolation. Child mental health conditions only had effects on isolation. The education polygenic score had significant associations with volunteering, religious service attendance and friendship; however, only effects on volunteering were significant in sibling fixed effects models. Conclusions: Lower levels of time preferences and higher levels of risk preferences, child health, and the education polygenic score likely have causal positive effects in building adult social capital, highlighting that investment frameworks similar to those used for human and health capital can be used to analyzed social capital and they should be considered in the development of policies to address social capital.

Keywords: Child Health
Economic Preferences
Economics
Polygenic Scores
Social Capital
Advisor: Laporte, Audrey
Strategic, Tactical, and Operational Decision-making in Crowd-shipping

The burgeoning last-mile delivery market coupled with the rapid evolution of sharing economy led to the emergence of crowd-shipping. This thesis studies three separate crowd-shipping problems involving strategic, tactical, and operational decision-making, particularly contributing to incorporating of uncertainties in decision-making via state-of-the-art optimization methods and solution strategies. The first crowd-shipping problem studies the strategic decision on parcel locker locations, considering both customer pickup and crowd-shipping. This problem considers customers' and crowd-shippers’ behavioural models to capture the decision dependency with respect to parcel locker locations and the delivery fee. The problem is formulated as a mixed-integer linear programming model for a given crowd-shipper compensation. The results suggest that companies can obtain a significantly higher profit by allowing customer pickup and crowd-shipping compared to the two alternative models, i.e., customer pickup and crowd-shipping in isolation. The numerical experiments demonstrate the value of the parcel locker location solution from the proposed model compared to the locations obtained from the customer pickup model. The second problem proposes a novel two-tier delivery system with crowd-shipping and mobile depots, considering the uncertainty in the availability of crowd-shippers. The problem is formulated as a two-stage stochastic programming model for tactical decisions on mobile depots stopping locations, and assigning customer packages to mobile depots. Enhanced decomposition algorithms are developed, which enable solving real-life instances. The computational experiments demonstrate the value of incorporating stochasticity and provide managerial insights from the stochastic model in the risk-averse versus risk-neutral settings. The third problem investigates a dynamic crowd-shipping problem with in-store customers as crowd-shippers for delivering online orders within a few hours. The problem is formulated as a Markov decision process for operational decision-making in matching online orders to crowd-shippers. An approximate dynamic programming (ADP) policy based on value function approximation is developed to obtain a highly scalable and real-time policy on matching orders to crowd-shippers while considering temporal and spatial uncertainty in the arrival of online orders and crowd-shippers. Our numerical analysis demonstrates the value of the proposed ADP policy over a myopic policy based on various performance measures.

Keywords: Approximate Dynamic Programming
Crowd-shipping
Last-mile delivery
Mobile Depot
Parcel Locker
Stochastic Programming
Advisor: Roorda, Matthew J
Bodur, Merve
A Head-Mounted Display-Based Augmented Reality Platform for Image-guided Media Delivery to the Heart

Heart disease is the leading cause of global mortality and is a significant precursor to heart failure. Recent advances in regenerative medicine have shown promise in improving cardiac function, but challenges in cell retention, targeting, and delivery remain to be explored prior to clinical use. During media delivery, surgeons rely on information from three-dimensional (3D) preoperative imaging, displayed using a two-dimensional (2D) monitor located adjacent to the surgical scene. This guidance strategy requires that surgeons mentally map information from the 2D monitor to their current 3D surgical context—potentially contributing to reduced accuracy during cell targeting and diminished therapeutic efficacy. The purpose of this thesis was to design an optical see-through head-mounted display (OST-HMD) led navigation framework to address the challenges associated with scar tissue visualization during targeted media delivery. Informed by prior failures and poor clinical uptake of OST-HMDs in surgical domains, we set out to address the human factors and workflow limitations which remain key hurdles to widespread adoption, including perception, registration, and context. To this end, my contributions are presented through three main bodies of work: (1) assessing user perception and usability with different locations of virtual content placement and display mediums; (2) reducing the contribution of occlusion and complex marker setup to tracking and registration error; and (3) investigating the feasibility of context-relevant information display during surgical tasks. In a point-and-trace task that simulated surgical targeting, I demonstrated the clear benefits of directly superimposed virtual content on an OST-HMD with regards to perceptual accuracy and task load. I then introduced a marker-free strategy to hand and surgical tool tracking that was robust to occlusion and demonstrated reasonable performance on a commercially available OST-HMD. Finally, I indicated the feasibility of context-relevant virtual assistance, for a set of predefined surgical tasks, to lessen the interaction burden on users during OST-HMD led guidance. I envision that my contributions will serve as meaningful steps towards the design and implementation of effective OST-HMD led navigation platforms to provide virtual guidance in the delivery of therapeutics to the heart—or for other interventions which benefit from virtual guidance.

Keywords: Augmented Reality
Computer Vision
Deep Learning
Head-Mounted Displays
Magnetic Resonance Imaging
Surgical Navigation
Advisor: Wright, Graham A
Ghugre, Nilesh R