VictorJuiz/thesis huggingface dataset:
The Association between Immigration Status and Stroke Incidence, Care and Outcomes
Keywords: care
ethnicity
immigration
incidence
outcomes
stroke

Immigrants to high-income countries have a lower cardiovascular disease incidence and mortality compared to host populations, a phenomenon termed the healthy immigrant effect. However, differences in stroke incidence, care and outcomes between immigrants and host populations have not been well-characterized. We studied the incidence, acute care, and short-term and long-term outcomes of stroke in immigrants compared to long-term residents in Ontario, Canada. People born outside of Canada who immigrated after 1985 were considered immigrants. Compared to long-term residents, immigrants had stroke at a younger age and had a lower adjusted hazard of stroke (hazard ratio [HR] 0.67; 95% confidence interval [CI] 0.66-0.68). Compared to long-term residents, immigrants were less likely to seek care for transient ischemic attacks, and among patients with ischemic stroke, immigrants received equal or better acute stroke care, had higher disability on discharge (adjusted risk ratio 1.18, 95% CI 1.13-1.22), and marginally lower long-term (15 years) mortality (adjusted HR 0.94, 95% CI 0.88-1.00). These associations varied with age at the time of stroke, stroke subtype, ethnicity, country of origin, and immigration class, highlighting heterogeneity in the observed healthy immigrant effect. While the lower incidence of stroke and the lower mortality following stroke in immigrants compared to long-term residents may suggest a healthy immigrant effect, the younger age at the time of stroke and the higher disability on discharge in immigrants compared to long-term residents highlights a higher risk of premature and disabling stroke in immigrants. Further research should evaluate the reasons for the observed differences, which could then inform the design of effective interventions to improve stroke outcomes for both immigrants and long-term residents.
Population Genomics of Herbicide Resistance Contemporary Agricultural Adaptation in Amaranthus tuberculatus
Keywords: De novo adaptation
Gene Flow
Plant Evolution
Rapid Adaptation
Standing variation

The evolution of resistance in response to herbicides is a striking example of repeated, human-induced evolution. While much is known about the effects of particular point mutations that confer resistance, the extent to which they arise repeatedly de novo, draw from standing variation, or spread across populations through gene flow is unclear (Chapter 4). Beyond these simple mutations, complex genetic bases such as gene amplification (Chapter 2) and polygenic architectures (Chapter 3) also contribute to resistance in weed populations, but their population genomics have yet to be characterized. In this thesis, I quantify the repeatability of resistance evolution across these genomic architectures by characterizing adaptive origins and causes and consequences for heterogeneity in the spread of resistance across the range of Amaranthus tuberculatus. A. tuberculatus is native to North America, with an annual life history and wind-pollinated dioecious sexual system. While historically found in riparian habitats, A. tuberculatus has successfully colonized agricultural landscapes and recently become problematic to manage in these ruderal settings due to widespread resistance to multiple modes of herbicides. In Chapter 5, I go on to test hypotheses about the timescale of adaptation to agricultural environments in A. tuberculatus, with phenotypic and genomic data from paired natural-agricultural collections grown in a common garden. I find that nearly all possible mechanisms contribute to the evolution of herbicide resistance and agricultural adaptation in A. tuberculatus, drawing from standing variation, repeated de novo mutations, and widespread gene flow among populations—highlighting the role of both slow gradual change and rapid genetic turnover during plant evolution to contemporary landscapes. Overall, my thesis contributes to our understanding of the extent and magnitude of evolutionary parallelism in the wild, population-level factors that influence the rate of evolution, and the timescale of adaptation to extreme selection and to human-mediated environmental transitions.
Backside-integrated III-V-on-Silicon Lasers and Modulators
Keywords: Hybrid lasers
Integrated optics
Modulators
Photonics

III-V-on-silicon (III-V-on-Si) bonding has emerged as a viable way to integrate lasers with Si photonic circuits at the wafer-scale. However, hybrid III-V-on-Si integration is often plagued by high thermal impedance and difficulty in co-integration with other materials. In this thesis, we design and demonstrate the first active devices on a new Back-Side-on-Buried-Oxide (BSoBOX integration process, in which the III-V material is introduced from the back of the silicon-on-insulator (SOI) wafer to address the common problems of III-V-on-Si integration. While designing and characterizing devices on the BSoBOX platform, the merits and limitations of the platform are also evaluated. First, we develop an optimization technique for producing short, broadband transitions between the SOI waveguides and the hybrid III-V-on-Si waveguides. The eigenmode-expansion based optimization process manipulates the lengths of short sub-tapers to produce a transition that maintains adiabaticity in the shortest length possible. Compared to an 80 µm long linear taper, with a power transfer efficiency of ∼85% at 1310 nm, the optimized design has a length of 80 µm and an efficiency ≥99.5% across the O-band. Next, two types of lasers are evaluated. We demonstrate distributed feedback lasers with threshold currents as low as 32 mA and 20 mW of waveguide-coupled power from a single end of the device. The side mode suppression ratio (SMSR) is around 50 dB within the range of 20 °C-60 °C and operation up to 80 °C is observed. We also demonstrate the first III-V-on-Si discrete-mode lasers, with the best device exhibiting 17 mW of waveguide-coupled power, a Lorentzian linewidth of 18 kHz and a SMSR ≥60 dB. The performance of these devices is comparable to the state-of-the-art III-V-on-Si lasers, despite this being the first iteration of the BSoBOX platform. Lastly, the first high-speed InP-on-Si modulators are designed and characterized on a frontside integrated platform that can be later converted to BSoBOX integration. The DC efficiency is 1.3 V·cm, roughly twice as high as lateral PN junction designs, while maintaining a comparable bandwidth of 30 GHz. Simulations show the BSoBOX designs will lead to a ∼4x improvement in efficiency and roughly 50% improvement in bandwidth compared to the current work.
Novel Strategies for the Prolonged Preservation of Donor Lungs Prior to Transplantation
Keywords: Ex vivo lung perfusion
Extended Preservation
Lung Preservation
Lung Transplantation
Oxygen
Temperature

The gold standard of lung preservation involves cold flushing the organ with a specialized solution, which is subsequently followed by storage in an ice cooler at a resting temperature of approximately 4°C. Developed over 30 years ago, this method continues to be used without significant advances due to its logistical simplicity. Although the primary goal of this approach is to shutdown cellular activity, several deleterious processes may ensue, ultimately compromising the length of time the organ can be kept in this state. According to international large registry reports, average clinical preservation times are only 5-6h. We hypothesized that through the implementation of novel strategies aimed to optimize the current cold storage protocol, prolonged preservation periods could be obtained. We first evaluated the effects of supplementing a novel extracellular oxygen within the standard preservation solution. Although the lungs are stored inflated with oxygen, some regions of the lung may be poorly inflated, leading to a risk of cellular damage over extended periods of time. By storing the lungs with an extracellular oxygen carrier supplemented solution during a prolonged preservation period, we show that cellular oxygen levels can be better maintained, and that post-transplant graft function is enhanced. We then go on to evaluate the role of temperature during prolonged cold storage periods. Previous literature has suggested 10°C to be the optimal lung storage temperature, however, little is known about the mechanism by which it is functionally superior. With the use of a simple thermoelectric cooler, we demonstrate prolonged storage at 10°C to be superior to current methods and identify mitochondrial protection to be a key determinant of this strategy. As a proof-of-concept, we further go on to demonstrate 10°C storage as a feasible approach to allow for clinical semi-elective transplantation. Lastly, we aimed to evaluate the potential of normothermic ex vivo lung perfusion (EVLP) to allow for multi-day preservation. Although initially developed as a tool for organ assessment, EVLP presents itself as an opportunity to interrupt the continuous manifestation of cold damage. By subjecting lungs to an intermittent EVLP protocol, we achieved successful 3-day lung preservation with excellent post-transplant outcomes.
Altered Landscapes: The Process of Conquest in the Eleventh-century Norman Chronicles of the Mezzogiorno and Sicily
Keywords: historiography
imperialism
landscape
literature
Mediterranean
multiculturalism

This dissertation examines the first generation of Latin chronicles patronized by the Norman conquerors of southern Italy and Sicily in the eleventh century: Amatus of Montecassino’s Ystoire de li Normant, William of Apulia’s Gesta Roberti Wiscardi, and, Geoffrey Malaterra’s De Gestis Rogerii Comitis et Roberti Guiscardi Ducis. These chronicles constitute meaningful assertions regarding the nature and actuality of Norman lordship in the region at a time of great precarity for the Siculo-Norman imperial project: the succession of the second generation of Norman lords. Indeed, I argue that these early texts must be examined in their pre-kingdom context, as the heavy work of conquest is often clearest in spaces of imperial precarity and anxiety. In addition, this dissertation is grounded in an understanding of the world-creating function of historical texts. It contends that each chronicle’s curated historical world reveals the ways in which the eternally-incomplete process of conquest continuously remade the collective identities, affinities and alterities, that gave shape to the socio-political, historical, emotional, and geographical landscapes of Norman Italy and Sicily. It first explores the internal logic of each history (and its respective historical world) individually, focusing on the specific preoccupations and aims of each historian, in order to explore their implications for current historians’ understanding of medieval conquest. These three distinct and interconnected worlds are then brought into conversation with each other in order to examine the logic of the Norman conquest more broadly. In particular, this dissertation contends that the process of conquest embodied in these histories was grounded in the twinned forces of alienation and appropriation as the chronicles worked to naturalize the bodies, emotions and lineage of the foreign conquerors within the landscape while simultaneously alienating their local subjects from it. In doing so, the chronicles obscured the rupture inherent in conquest behind the mask of continuity provided by these acts of naturalization.
Mapping the Conformational Landscape Spatial Organization of G Protein-coupled Receptors using Single-molecule Fluorescence
Keywords: Fluorescence
FRET
GPCRs
membrane proteins
protein dynamics
Single-molecule

G protein-coupled receptors (GPCRs) are the largest class of transmembrane proteins, making them an important target for therapeutics. Several aspects of GPCR signalling pathways, however, still remains elusive. In this thesis, two key aspects are addressed: the role ligands play in shaping the conformational landscape of GPCRs, and the oligomeric size of GPCRs during different stages of signalling. Here, a combination of ensemble and single-molecule fluorescence techniques were used to investigate the above, whereby the A2A adenosine receptor (A2AR), and the M2 muscarinic receptor (M2R) were used as model systems. Using single-molecule Förster Resonance Energy Transfer (smFRET), it was shown that A2AR exhibits a high degree of basal activity, and that the relative populations of inactive and active states is modulated upon binding of ligand. Furthermore, photoinduced electron transfer, monitored via Fluorescence Correlation Spectroscopy (PET-FCS), showed that ligands also effect the dynamics within and between several conformational states of A2AR. This work provides a quantitative approach to study how ligands modulate the conformational landscape of GPCRs. The oligomeric size of detergent-purified M2R and its attendant G protein (Gi1) were determined using single-molecule Photobleaching (smPB) analysis via a total internal reflection fluorescence (TIRF) microscope. The smPB analysis revealed that both M2R and Gi1 were oligomeric in nature prior to coupling, predominantly consisting of tetramers for M2R and hexamers for Gi1, regardless of ligand. In the coupled state (RG), it was found that a tetrameric M2R couples to tetrameric Gi1, whereby the binding of nucleotide (guanosine triphosphate) causes the disassembly of the RG complex, and a reduction in the oligomeric size of Gi1 from tetramers to dimers. The binding of an inverse antagonist also results in disassembly of the RG complex, and a reduction in the oligomeric size of M2R from tetramers to monomers or dimers. The work suggests that active M2R is tetrameric and solely capable of binding to tetrameric forms of Gi1, whereas the active form of Gi1 is dimeric and only activatable when coupled to M2R.
Vortex-induced Vibration and Forced Oscillation Motion of a Circular Cylinder Fitted with a Single Spanwise Tripwire
Keywords: Cylindrical structure
Flow–structure interactions
Forced oscillation motion
Tripwire
Vortex-induced vibration

This experimental study consisted of two main parts. The first part investigated the control induced by a spanwise tripwire on a circular cylinder undergoing one-degree-of-freedom vortex-induced vibration (VIV). The cylinder vibrates in the cross-stream direction as a result of the fluid forcing in a recirculating water tunnel. Changing mass and damping ratios in the test rig allowed the investigation at different VIV response branches. The tripwire diameter was 6.25% of the cylinder diameter. Experimental research was conducted by attaching the large-scale tripwire along the span of the cylinder at various angular positions ranging from 0° to 180° (with respect to the most upstream point of the cylinder). Along with measuring the trajectory of the cylinder motion, the instantaneous velocity field in the near wake of the cylinder was obtained simultaneously at a fixed Reynolds number of 10,000 (based on the cylinder diameter) using a Particle Image Velocimetry (PIV) system. Various vortex-formation modes induced by the tripwire were observed. It was shown that the oscillation pattern, frequency, and amplitude of the cylinder can be altered significantly depending on the angular position of the tripwire and the VIV response branch. For specific tripwire positions, increases of up to 52 times and decreases of up to 98% were identified in the oscillation amplitude of the tripped cylinder compared to the amplitude of the clean cylinder.The second part of the study investigated the effects of the tripwire on the flow structure behind a circular cylinder forced to oscillate harmonically at prescribed amplitudes and frequencies in the cross-stream direction. Oscillation amplitudes are 0.05, 0.3 and 0.6 times the cylinder diameter, and oscillation frequencies are 0.61, 0.8, and 1 times the vortex shedding frequency of the stationary clean cylinder counterpart. For a fixed oscillation amplitude and frequency, the tripwire can either induce intermittent switching between various vortex shedding modes or cause a wake mode to be dominant during the entire observed oscillation motion by altering the vortex shedding mechanism. The wake of the tripped cylinder undergoing the lowest amplitude forced oscillation motion showed resemblance to the wake of the stationary tripped cylinder.
Design and Applications of Printed-circuit-board Huygens' Metasurfaces
Keywords: Antenna
Electromagnetic
Metasurface
Refraction
RF
Wave

As applications involving electromagnetic waves as carriers of energy and information have become common in society, the ability to tailor and control electromagnetic fields has become proportionally more demanding. In recent years, with the emergence of the Huygens' metasurface, applications and functionalities previously thought to be unachievable have been demonstrated. Due to their intimate and complete control over incident electromagnetic waves, Huygens' metasurfaces theoretically allow the arbitrary manipulation of the involved electromagnetic fields. In this thesis, demonstrations of designs and applications of these remarkable devices are presented. Applications including beam collimation, angle doubling, and perfect refraction are investigated. Additionally, realization of printed-circuit-board prototypes are detailed with designs utilizing stacked-layer and wire-loop structures. Throughout the different applications, both transverse-electric and transverse-magnetic designs are shown. Furthermore, to demonstrate the versatility of Huygens' metasurfaces, the operational frequency of the prototypes ranges from K-band to V-band. Details regarding theoretical and fabrication trade-offs are also considered for all presented designs. Theoretical aspects such as zero loss, passivity, reciprocity, impedance equalization, and local power conservation are studied in detail. Moreover, design and fabrication considerations are also investigated thoroughly. By analysing the designs via fullwave simulation tools and experimental measurements, the functionalities of the presented metasurfaces are validated. Additionally, the frequency responses of the designs were also presented and discussed. Lastly, future opportunities and design considerations were also outlined. Although the designs presented in this thesis only serve as early examples of Huygens' metasurfaces, the achieved results demonstrate the capability and versatility of these devices for achieving various applications. Due to these remarkable abilities, the Huygens' metasurface will undoubtedly become an indispensable tool for solving increasingly challenging electromagnetic problems in the near future.
In-between Places: A Narrative, Arts-informed Exploration of the Knowledge, Values, and Beliefs of English Language Instructors
Keywords: arts-informed
mid-career EAL instructors
multiple case study
narrative
professional development
professional learning community

This research study, written as a narrative, arts-informed multiple case study, provides a model of reflective practice for TESOL professionals. Based on a foundation of holistic education, this study is an in-depth exploration of the teacher-self, centred on the hearts, minds, and behaviours of four English as an Additional Language (EAL) instructors of adults at mid-career. The central question of this study was, In what ways do English as an Additional Language (EAL) instructors of adult learners describe transformations in their knowledge, values, and beliefs about teaching and learning over the course of time? Engaged in an 8-month long Professional Learning Community (PLC) using Kolb’s Experiential Learning Cycle as the framework for reflection and growth, participants completed creative and reflective writing tasks and participated in group discussions in order to investigate their knowledge, values, and beliefs and how these shaped their perspectives, impacted their decision-making, and influenced their behaviours both inside and outside the classroom. Through actively investigating and constructing meaning from their lived experiences, participants imagined and created new ways of being and teaching. Participants were interviewed 4 years and 13 years after their participation in the PLC in order to identify the most significant changes in their knowledge, values, and beliefs. Findings showed that peer-based, continued professional development (CPD) involving writing and dialogic reflection are powerful methods and means for mid- to late- career EAL instructors to uncover hidden assumptions, develop alternate perspectives on experiences, build upon their diverse knowledge, and develop and share their expertise. Findings also showed an impact on the participants’ knowledge, values, and beliefs as they each progressed through various life stages and career transitions. While certain values remained the same over time, others changed as a result of the participants’ personal and professional growth. Implications of this study address research and practice at three levels. First, at the individual level, focusing on educators and students, second, at the level of professional development practices, and third, at the policy level related to professional learning and development within the community college context.
Long-term Analysis of Toronto-Area Atmospheric Composition
Keywords: Atmosphere
FTIR
TAO
Trends

This thesis examines total columns of C2H2, C2H6, CH4, CH3OH, CO, H2CO, HCl, HCN, HCOOH, HF, HNO3, N2O, NH3, and O3 measured using Fourier transform infrared (FTIR) spectroscopy to study Toronto-area atmospheric composition. The thesis has three scientific objectives: to quantify trends in the time series of trace gas concentrations, to determine how emissions from biomass burning events affect air quality over Toronto and whether observations in Toronto can be used to quantify wildfire emissions, and to examine the spatial representativeness and temporal variability of the FTIR NH3 columns over Toronto.Trends and enhancement events were determined by fitting trended Fourier series to the total columns, and bootstrapping was used to identify the statistical significance. Trends from 2002 to 2019 were examined, and the GEOS-Chem chemical transport model was used to identify major sources of CO and CH4 over Toronto, which were CH4 oxidation and wetland emissions, respectively. Transport of wildfire plumes over the site results in enhanced columns of biomass burning species. Several simultaneous enhancements of CO, HCN, and C2H6 were observed, and the measured columns were used to derive emission ratios and emission factors for HCN and C2H6 for fire events in 2012, 2015, and 2017. For the 2015 and 2017 events, simultaneous enhancements of HCOOH and CH3OH were observed, and their emission ratios and emission factors were also examined. Atmospheric NH3 is a pollutant, and a major source of fine particulate matter. In this study, three NH3 datasets were used: TAO FTIR total columns, three years of surface in situ measurements, and ten years of total column measurements from the Infrared Atmospheric Sounding Interferometer (IASI). The datasets were used to quantify NH3 temporal variability over Toronto, Canada. All three time series showed positive trends in NH3 over Toronto: 3.56 ± 0.85 %/year from 2002 to 2019 in the FTIR columns, 8.88 ± 5.08 %/year from 2013 to 2017 in the surface in situ data, and 8.38 ± 1.54 %/year from 2008 to 2018 in the IASI columns. The multiscale datasets were also compared to assess the representativeness of the FTIR measurements.