VictorJuiz/thesis huggingface dataset:
Experimental Investigation of Heat Transfer in Laser Sintered and Wire Mesh Heat Exchangers

In this thesis, an experimental investigation of fluid flow and heat transfer through open cell porous wire mesh and laser-sintered heat exchangers is presented. The thesis consists of two main sections that describe how to create a compact heat exchanger that uses open-cell porous structures. In the first part of the thesis a new method of building compact heat exchangers using direct metal laser sintering (DMLS), a technology which enables heat exchangers with a predetermined, fully controlled internal geometry to be built was investigated. Laser-sintering was used to fabricate stainless steel heat exchanger channels filled with struts arranged to form either cubic, round-strut tetradecahedral or thin-strut tetradecahedral cells. The objective was to demonstrate that the effect of adding internal struts is not simply to increase surface area, but that cell geometry has a significant effect on both heat transfer and fluid flow. This section also describes the importance of the connection between the porous structures, which is used to improve the performance of the heat exchanger, to the main body of the heat exchanger. It was possible to design internal geometries that maximize heat transfer while minimizing weight and frictional losses. In the second part of the thesis, a simple method of increasing the heat transfer surface area has been developed by using a twin wire-arc thermal spray system to generate a dense, high strength coating that bonds porous structures, like wire mesh and perforated sheets, to the plain tube heat exchangerâ s outside surfaces. The porous structure and the main body of the heat exchanger must be well bonded together to minimize thermal resistance. The extended surfaces of the wire mesh and perforated sheet enhanced the heat transfer performance of the tube heat exchangers. Finding the right balance between pore density and number of screens of the porous structures is crucial for maximizing the heat transfer performance of the heat exchangers.

Keywords: Heat Exchangers
Heat Transfer
Laser-Sintered Heat Exchangers
Laser Sintering
Wire-Arc Thermal Spraying
Wire Mesh Heat Exchangers
Advisor: Chandra, Sanjeev
Multi-Camera Active-Vision for Markerless Shape Recovery of Unknown Deforming Objects

This thesis proposes a multi-camera active-vision reconfiguration system which selects camera poses on-line to improve the shape recovery of a priori unknown, markerless, deforming objects in dynamic environments. The objectives of shape recovery are defined as surface sampling accuracy, and shape completeness. The completeness objective is generalized for both solid and surface-based objects as the maximization of surface visibility. Thus, improving the recovered shape of target objects is shown to be analogous to maximizing the surface area visibility. This improvement is achieved through the on-line reconfiguration of multiple cameras. The system developed herein is composed of a shape recovery method, a robust tracking algorithm, and a multi-camera reconfiguration method. The shape recovery method is based on a modular fusion technique that produces a complete 3D mesh-model of the target object. The method fuses triangulation data with a visual hull to maximize recovery accuracy. The modularity of the method lies in the ability to modify data filtering techniques to improve modelling accuracy, and interchange stereo correspondence features. The adaptive particle filtering algorithm produces a deformation estimation of the recovered model from the tracking data. The algorithm automatically adapts to the quantity of tracking data available and changes in the objectâ s dynamics. The modularity of the algorithm allows modifications in terms of the number of particles and motion models for task-specific implementations. The reconfiguration method consists of a robust stereo-visibility objective function, workspace discretization, and a path planner. The complete system can improve the shape recovery of a priori unknown deforming objects in obstacle-laden environments when compared to static camera methods. To validate the proposed system, extensive simulations and experiments were conducted. The simulations tested the system in comparison to static multi-camera systems, and ideal camera placement where the object model was a priori known and the cameraâ s dynamics were unconstrained. Simulation results showed the proposed methodology outperformed static cameras and approached the performance of ideal camera placement in a dynamic, obstacle-laden environment. The experimental results showed similar improvement in shape recovery when comparison to a static camera system in an obstacle-laden environment.

Keywords: Computer Vision
Deformable
Markerless
Multi-Camera
Reconfiguration
Shape Recovery
Advisor: Benhabib, Beno
Material Architectures for Improved Light and Carbon Supply in Microalgal Photobioreactors

This thesis explores the use of materials to improve light and carbon supply to microalgal cultures. These resources are the primary growth factors that limit productivity and, ultimately, the cost of biomass generation. Three unifiable approaches to supply are separately studied with performance evaluations based on culture densities achieved with the cyanobacteria Synechococcus elongatus, relative to controls. The potential performance of these supply approaches are compared with conventional approaches reported in the literature. The first study explores light supplied from thin, planar, glass waveguides that illuminate surface-grown biofilms using frustrated total internal reflection (FTIR). A biofilm with uniform density (1.0 ± 0.3 × 109 mL−1) grew in a wide range of intensities that exceeded the high and low limits for suspension cultures. This extended growth regime is explained by semi-coherent, high-intensity light confinement in the waveguide, combined with intensity-smoothing by biofilm morphology. The performance suggests potential for greater growth areas and intensity ranges, with volumetric module densities on the order of 108 mL−1. However, glass and other gas-impermeable materials used in reactors to improve light supply often negatively affect carbon supply and vice-versa. The second study explores materials that permit combined waveguide illumination and CO2 permeation. Use of cellulose acetate butyrate (CAB) waveguides doubled the density of suspension cultures relative to impermeable waveguides, but required elevated CO2. Fixed biofilm cultures, compatible with the established light and carbon supply approaches, can provide greater photosynthetic efficiency, but productivities suffer from respiration in the dark portions of the biofilm. The third study then uses cultures fixed in calcium-alginate hydrogels to demonstrate photoactive light penetration in the low density bulk. Over time, microalgal growth within the hydrogel produces a thin, high-density surface layer due to high local light and CO2 access. This hydrogel approach presents the opportunity for partial, skim-harvesting of this top layer. The effect on production of periodically harvesting the dense top layer was quantified. Over 18 days of cultivation, productivity was greatest in hydrogels formed with 150 mM Ca2+, and subject to 3-day harvest periods – especially in the first layer. Harvested biomass yields became more uniform with additional harvests. This growth format permits thick cultures that both experience photoactive light and produce at high density. Each of these three approaches has demonstrated improvements to light and/or CO2 delivery to microalgal cultures, leveraging unique materials and approaches. Collectively, this thesis demonstrates proof-of-principle for next-generation approaches to achieving high-density microalgal photobioreactors.

Keywords: Biofilm
Cyanobacteria
Hydrogel
Microalgae
Photobioreactor
Waveguide
Advisor: Sinton, David
Development of Novel Anti-Respiratory Syncytial Virus Therapies

Respiratory syncytial virus (RSV) is a leading cause of mortality in infants and young children. Despite the RSV disease burden, no vaccine is available and treatment remains non-specific. New drug candidates are needed to combat RSV. Towards this goal, we investigated two broad strategies to control RSV infection. First, we examined the utility of delivering an anti-4-1BB agonist antibody to enhance CD8 T cell costimulation in a mouse model of RSV infection. This strategy enhanced CD8 T cell numbers, however failed to reduce RSV titers in the lung. We found that this was likely due to reduced RSV specific CD8 T cells in the lung. Overall, this strategy did not attenuate RSV associated disease outcomes and was associated with increased morbidity. Second, we screened over 2000 FDA approved compounds to identify approved drugs with novel anti-RSV activity. Cardiac glycosides, inhibitors of the membrane bound Na+/K+-ATPase, were identified to have anti-RSV activity. Cardiac glycosides diminished RSV infection in HEp-2 cells and in primary human airway epithelial cells grown at an air liquid interface. Digoxin, an FDA approved cardiac glycoside, was further able to inhibit RSV infection of community isolates of RSV in primary nasal epithelial cells. Our results suggest that the antiviral effects of cardiac glycosides are primarily dependent on changes in the intracellular Na+ and K+ composition. Consistent with this mechanism, we subsequently demonstrated that the ionophoric antibiotics salinomycin, valinomycin, and monensin inhibited RSV in HEp-2 cells and primary nasal epithelial cells. Our data indicate that the K+/Na+ sensitive steps in the RSV lifecycle occur within the initial 4 hours of virus infection, but do not include virus binding/entry. We employed an RSV mini-replicon assay allowing the independent assessment of RSV-specific RNA synthesis. Our findings demonstrated that digoxin does not alter the RSV RNA polymerase. Future studies will focus on the possibility that digoxin and other ion-modulating drugs may impact viral uncoating (i.e. release of viral nucleic acid from RNP complex).

Keywords: antiviral
cardiac glycoside
ion homeostasis
ionophore
Respiratory syncytial virus
Advisor: Moraes, Theo J
Hegele, Richard G
Unpacking Social Movements' Democratizing Impact: The Case of the Lesbian, Gay, Bisexual, and Travesti Movement in Brazil

This dissertation examines the impact of the Brazilian lesbian, gay, bisexual, and travesti (LGBT) movement on the construction of a more inclusive democracy. In order to do this, I develop a framework for assessing the “whether,” “how,” and “why” of social movements’ democratizing impact, based on an understanding of substantive democracy that sees the inclusion of marginalized groups as a central test. Substantive democratic inclusion would require the autonomous agency of the social movement fighting for the interests of the marginalized group in question; public recognition of the marginalized group via the increased visibility and more widespread toleration of its members in the public sphere; the participation of marginalized groups in decision-making institutions, by increasing their access and influence over policy-makers, as well as their presence in relevant institutional spaces; concreteness of the gains made by the movement, particularly in the form of public policies; and universality in policy effect, addressing more systemic inequalities that affect those most strongly marginalized within that population. By focusing on the period from the emergence of the LGBT movement in 1979 to the end of the first term of Dilma Rousseff’s presidency in 2014, and examining movement activity in the public sphere and actions aimed at the State (federal executive, legislative, and judiciary branches), I argue that the movement has achieved an incomplete democratic inclusion of sexual minorities. This incompleteness is characterized by headway in terms of autonomous agency, recognition, and participation, but limitations on the concreteness and universality of gains. This pattern of impact is shaped by three broad factors, namely the historical structures of marginalization, the institutional framework activists face in their engagement with the State, and the dominant regime of interest mediation. In the conclusion, I engage in a comparison with other social movements in Brazil to contextualize these findings.

Keywords: Brazil
democratization
inclusion
intersectionality
LGBT
social movements
Advisor: Rayside, David
Fabrication and Characterization of Linear and Nonlinear Photonic Devices in Fused Silica by Femtosecond Laser Writing

Femtosecond laser processing is a flexible, three-dimensional (3D) fabrication technique used to make integrated low-loss photonic devices in fused silica. My work expanded the suite of available optical devices through the design and optimization of linear optical components such as low-loss (

Keywords: Femtosecond laser
Glass waveguides
Optical circuits
Advisor: Qian, Li
Herman, Peter R
The quality of care among older adults with diabetes comorbid with other chronic conditions

The management of people with multiple chronic conditions requires understanding the extent to which concurrent chronic conditions contribute and interact to affect the patientâ s health status, as well as assessing the risk and benefits of various strategies for the treatment of complex needs in patients. A single condition focus in both clinical care and research remains and limits the assessment of care for people with multiple chronic conditions. The overall aim of this project was to evaluate the quality of overall care for older adults with selected disease combinations in ambulatory care settings. The first study aimed to identify a set of evidence-based and valid quality indicators for evaluating ambulatory care for older adults with selected chronic conditions, including diabetes, hypertension, chronic ischemic heart disease, major depression and osteoarthritis. The second study aimed to critically appraise the identified quality indicators and select a set of indicators for evaluating the quality of care for older adults with diabetes with comorbid concordant and discordant chronic conditions. The third study aimed to examine the difference in the quality of care between patients with 2 vs. 1 selected concordant vs. discordant comorbid conditions, and to examine associations of quality of care and hospitalizations among older adults with selected disease combinations. The study findings suggest that older adults with diabetes are at risk of suboptimal care with additional selected comorbid conditions, especially those with discordant comorbid conditions. The study findings also support the importance of continuity of care for older diabetes patients with comorbid chronic conditions. The study findings suggest that the likelihood of hospitalizations increases with the number of prescribed drugs among older adults with comorbidities. There is a need for a holistic approach in education and clinical care of older adults with diabetes taking into account concomitant conditions that affect patientâ s health status. Future research is needed for measuring the quality of care in the larger diabetes population and reporting by different stratifications, including age, sex, primary care models to see if there are any patterns in certain groups and target the interventions towards improving practices for specific sub groups.

Keywords: Concordant/discordant comorbidities
Continuity of care
Healthcare utilization
Multimorbidity
Polypharmacy
Quality of care
Advisor: Wodchis, Walter P
Characterization of the immunoregulatory roles of IFN-β in T cells and dendritic cells

Multiple sclerosis (MS) is an autoimmune disease that targets the central nervous system (CNS). Interferon (IFN)-β was the first approved therapy for relapsing-remitting MS more than 20 years ago, however, its mechanism of action remains ill-defined. Using a myelin oligodendrocyte glycoprotein (MOG)-induced murine experimental autoimmune encephalomyelitis (EAE) model for MS, our earlier studies identified that IFN-β-/- mice exhibit an earlier onset and a more rapid progression of disease compared to IFN-β+/+ mice. CD4+ T cells, specifically of the Th17 lineage, are posited to be pathogenic in MS and in EAE, and CD11c+ dendritic cells (DCs) are critical antigen-presenting cells that have the potential to regulate pathogenic T cells in MS and EAE. Accordingly, we investigated the immunoregulatory effects of IFN-β on CD4+ T cells and DCs. Our studies revealed that CD4+ T cells isolated from IFN-β-/- mice are primed to polarize to the Th17 lineage, associated with expression of Th17-associated cytokine receptors. Stimulation with a cocktail of Th17-inducing cytokines led to increased expression of Th17-associated genes in IFN-β-/- Th17 cells compared to IFN-β+/+ Th17 cells, suggestive of a regulatory role for IFN-β in determining the Th17 cell transcriptome. Consistent with these findings, we observed a greater proportion of Th17 cells in the LNs of IFN-β-/- mice compared with IFN-β+/+ mice during EAE, with increased numbers of CD4+ T cells in the CNS of IFN-β-/- mice, regardless of stage of disease. We identified that IFN-β exerts immunoregulatory effects on DCs, associated with determining cytokine production and expression of co-stimulatory activation markers. IFN-β-/- DCs drive increased proliferation of MOG-transgenic CD4+ T cells, and produce more IL-6 and IL-23, critical for induction of Th17 cells. Finally, we provide evidence that IFN-β regulates the migration of DCs into the CNS during EAE, by modulating STAT1-dependent CCR7 expression. Taken together, our data indicate immunoregulatory roles for IFN-β in suppression of Th17 cells and in limiting the activation and trafficking of DCs during EAE.

Keywords: dendritic cell
EAE
Interferon-beta
Th17
Advisor: Fish, Eleanor N
Investigating the Role of Tumour-Stroma interaction in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma is the sixth leading cause of cancer-related death worldwide. Although most patients initially respond to treatment, many will eventually recur and die and die of their disease. Understanding the impact of the components of the tumour microenvironment on disease progression is essential to effectively treat HNSCC. The work described in this thesis provides a better understanding of the relationship between tumour cells and fibroblasts and describes novel therapeutic targets for further testing. First, I characterized carcinoma-associated fibroblasts (CAFs) and their effect on tumour cell behaviour in vitro and in vivo. Second, using laser-capture microdissection (LCM), I obtained pure populations of tumour and normal epithelial cells as well as tumour-associated and normal stromal cells. From these cells I obtained transcriptomic profiles and used this data to identify candidate molecular interacting partners utilized by tumour and stromal cells to communicate with each other. Finally, I also use these profiles in combination with publically available data gene expression and clinical data from the The Cancer Genome Atlas (TCGA) to characterize the association between stromal genes and clinical outcomes.

Keywords: fibroblasts
head and neck cancer
stroma
tumour microenvironment
Advisor: Ailles, Laurie E
Math fluency development in the early elementary grades and the role of the summer break, inattention, and working memory

The current dissertation examined factors thought to influence the developmental dynamics of basic math fluency skill (addition and subtraction). The overarching goal of this research was to examine growth patterns in addition and subtraction fluency across Grades 1 through 4 while taking into account the effects of the non-instructional period over the summer months. This was accomplished using an accelerated longitudinal design within the framework of hierarchical linear modeling. A cumulative pattern of growth was observed over time for each fluency measure. Differences between addition and subtraction growth trajectories were found and are discussed. This dissertation also aimed to examine the respective roles of verbal working memory, visual-spatial working memory, and teacher ratings of classroom inattention in the development of math fluency while controlling for sex and parent level of education. This was done from a piecewise perspective, that is, by considering whether these cognitive and behavioral factors exerted differential effects based on seasonal patterns (i.e., skill growth that occurs within the school year (excluding the summer), and the growth that occurs across grades (including the summer)). Differential seasonal patterns were identified: Visual-spatial working memory was predictive of skill development specific to the school year, whereas teacher-rated inattention was a key longitudinal predictor of weaker math fluency, across the years, including the summer months. Implications for research and educational practice are discussed.

Keywords: Inattention
Math fluency
Summer slowdown
Working memory
Advisor: Tannock, Rosemary
Claiming the Road: Intersectional Mobilities and Unfreedom among Migrant Farmworkers in Canada

This study considers the travel patterns, practices and conditions that shape how migrant farmworkers circulate in rural southwestern Ontario. While migrants in Canada’s Seasonal Agricultural Worker Program (SAWP) do not exercise occupational mobility and are housed in employer-provided accommodations, they are otherwise legally entitled to circulate freely in Canada. In practical terms, however, most experience significant mobility barriers. The study investigates the mechanisms by which migrant farmworkers are confined and immobilized to farm spaces on systemic levels, contributing to a vein of research on the immobilities that pervade everyday life for transnational, low-wage labour migrants. I show how localized mobility controls placed around migrants as well as inadequate transportation create a “mobility fix” for farm operators and state actors. Technologies of confinement that immobilize migrant farmworkers are justified through racial and sexual ideologies about migrants being a threatening presence in rural Canada, while permitting high levels of value to be extracted from migrants’ labour. The dissertation is organized as three empirical journal articles which are preceded by a chapter on research methods. In the first article I document how a purported problem with transient farm labour migration to Ontario from Quebec and Atlantic Canada was constructed in the 1960’s and 1970’s. In response, the Canadian government devised the SAWP as an institutional mechanism to undercut transnational migrants’ constitutional and practical mobility rights, rights that transients harnessed. This chapter reveals how enacting controls around migrants’ local mobilities has been crucial to the “making” of migrant agricultural workforces in Canada. In the second article I identify how systemic immobilities for SAWP workers are enacted by Canadian family farm operators. I show how Canadian family farms benefit from high levels of personal and intimate interaction with SAWP employees. I identify how operators impose high limitations and constraints as to when, where, and how migrants can travel beyond formal work hours. Finally, the third article examines how migrants have forged bicycling geographies in rural places and how migrant bicyclists are perceived in Canadian communities. Migrants are more vulnerable as bicyclists, do not bike out of choice, and have become subjects of bike safety education. I argue that racial and economic forms of exploitation as well as socio-spatial exclusions inflect actually existing bicycling geographies.

Keywords: Agriculture
Canada
Labour Migration
Mobilities
Transportation
Unfree Labour
Advisor: Walks, Alan R.