VictorJuiz/thesis huggingface dataset:
Plasmonic and Catalytic Properties of Shape-Controlled Metal Nanoparticles and their Assemblies
Keywords: catalysis
nanoparticles
plasmonics
self-assembly

This work explores the effect of the shape of metal nanoscale building blocks on the structural, optical, and plasmonic properties of their assemblies, as well as on the catalytic performance and hydrogen interactions of individual nanoparticles with specific shapes. In Chapter 3, I describe the linear self-assembly of bifunctional metal nanoparticles in the presence of monofunctional nanoscale chain stoppers. Chain stoppers with controlled reactivity were synthesized allowing control over the morphology of the self-assembled structures. Analysis of the degree of polymerization of linear nanostructures provided information about self-assembly kinetics, side reactions, and the distribution of species in the reaction. This work facilitated testing of theoretical models developed for molecular polymerization and fabrication of linear nanoparticle assemblies with controllable properties. In Chapter 4, I developed linear solution-based self-assembly of cubic metal nanoparticles, examined the morphology of the nanocube chains and their optical characteristics. In comparison with chains of nanospheres with similar dimensions, compositions, and surface chemistry, predominant face-to-face assembly of nanocubes leads to a larger volume of plasmonic hot spots, uniform electromagnetic field enhancement in the gaps between nanocubes, and a new coupling mode for nanocube chains, associated with Fabry−Perot structure. In Chapter 5, I investigated plasmon-mediated enhancement of the catalysis by palladium-based nanoparticles with different shapes and composition, bearing surface plasmon resonance in visible range. The photocatalytic activity of palladium-based nanoparticles depended more on their shape than internal structure. These findings pave the way for the design of palladium nanocatalysts with enhanced performance acting under visible light illumination. In Chapter 6, I developed a facile scaled-up synthesis of monodisperse palladium nanoparticles with various shapes, stabilized with a mesoporous silica shell. Hydrogen-nanoparticle interactions were studied using temperature programmed desorption. These findings help elucidate the nature of hydrogen interactions with topologically different palladium nanoparticles.
Delineating the Molecular Mechanisms of KIF7 in Vertebrate Hedgehog Signal Transduction
Keywords: Hedgehog signalling
Kif7

The Hedgehog (Hh) signalling pathway plays important roles in embryonic development and for adult tissue homeostasis and regeneration of multi-cellular organisms. Mutations in components of this pathway often result in human developmental disorders and cancer. The primary cilium, a microtubule based extension from the cell surface is required for Hh signalling in vertebrates. Hh ligand binding to the Patched (Ptch1) receptor leads to the ciliary accumulation and activation of the seven transmembrane protein Smoothened (Smo) and changes the localization of several pathway components within primary cilia subdomains. How Smo activation affects the localization of effector proteins in cilia and how this relates to the activation of target genes is unclear. Genetic and biochemical analysis revealed that the kinesin family protein 7 (Kif7) trafficks to the primary cilia upon pathway activation and fulfills dual positive and negative roles during mouse Hh signalling. Through proteomic and biochemical analysis, we aim to better understand the molecular mechanisms underlying the functions of Kif7 in vertebrate Hedgehog signalling. Using a mass spectrometry-based proteomic approach, we identified Liprin-1 (PPFIA1) and the PP2A phosphatase as Kif7-interacting proteins, and showed that these proteins regulate Kif7 phosphorylation and its activity. We further identified DYRK2 as a protein kinase that phosphorylates Kif7. Overall, our study identified phosphorylation as a post-translational modification that dictates Kif7 localization within primary cilia and its control of Gli transcriptional activity. Lastly, through biochemical assays we examined the relationship between SuFu and Kif7, two key regulators of the Hh pathway. Collectively, these studies highlight the importance of Kif7 in vertebrate Hh signalling.
An Existential Perspective on the Role of Human Agency in the Retraining of Immigrant Skilled Workers in Canada
Keywords: Canadian retraining
career transition
existential theory
human agency
immigrant career
immigrant retraining

This qualitative study explored the career re-development of immigrant professionals in Canada by centering the investigation on their Canadian retraining journey. The goal of this study was to provide a deeper understanding of the transition issues, retraining decision-making process, retraining experiences and outcomes, and coping strategies of the immigrant professionals to uncover the role of human agency in dealing with the existential givens of their Canadian career re-development. Twenty participants, 11 females and 9 males between the ages of 30 and 50, were interviewed for this study. The participants held at least a bachelor’s degree and had at least 3 years of work experience prior to their migration. They received Canadian retraining and had at least 1 year of post-retraining Canadian work experience. Semi-structured interviews were completed and the interview transcripts were analyzed using grounded theory qualitative analysis approach. Similar to previous research findings, the immigrant professionals in this study had intact career identities and meaning prior to their migration. Many participants were confident about transitioning into their original professional field in Canada with some participants having expected to pursue Canadian retraining. The participants, however, experienced systemic career transition barriers in Canada, such as language and acculturation barriers, discrimination, isolation, and non-recognition of their foreign credentials and work experience by Canadian employers. They completed Canadian retraining to cope with these barriers and pursue their career goals. Almost all of the participants shared that their retraining facilitated their career re-development and many were either undergoing or planned on pursuing additional retraining to improve their future career prospects. Throughout their career re-development process, focusing on their long-term career goals (which provided them with meaning), acceptance and openness, and social supports provided them the perseverance to utilize their human agency. The participants accessed their human agency to revise their meaning-making, create a plan of action, and take action with the intention of pursuing their long-term goals. This career re-development process is summarized in the model proposed by this study, the Existential and Human Agency Model of Career Re-development. The implications of the findings of this study for policy, professional resources, and immigrant professionals are discussed. Suggestions for future research directions are provided.
Discourses and Realities of Online Higher Education: A History of [Discourses of] Online Education in Canada’s Open University
Keywords: Discourse Analysis
Distance Education
Foucault
Higher Education
Online Education
Open University

My dissertation research aims to develop a comprehensive account for the current state of online higher education beyond the common social and educational expectations about the adoption of online education. Online education, according to dominant discourses in higher education, is commonly expected to (a) enhance educational accessibility to university education and (b) improve the quality of university instruction. And, this expectation further produces an imperative for its rapid adoption across all higher education institutions. However, my research fundamentally challenges these two rhetorical discourses, by providing an in-depth description of the disjunction between such discourses and the realities of praxis. Drawing on key concepts from Michel Foucault and Mikhail Bakhtin, I trace the historical development of these two discourses as two institutional principles of openness and innovation in an open university. The complex relationships between the institutional discourses and peoples’ practices, mediated by multiple factors are carefully addressed. My analysis reveals that multiple understandings of openness and innovation co-exist within the university, and members take different pedagogical approaches to online education according to their own understanding of those two principles. As a result, openness and innovation often conflict with each other at the operational level, and the conflict is also visible within the ongoing struggles between instructors and learning designers, with regard to the adoption of a particular form of online pedagogical practices. In summary, my findings demonstrate how the adoption of online education may introduce new problems and potentially oppressive power relationships among stakeholders in higher education, unlike the rhetorical claims that simply promote online education as a revolutionary solution for diverse social and educational problems. This disjunction continues to increase and is intensified by the existing instructional theory-practice gap in the academic field of online higher education. I urge that researchers and educators in online higher education as a united group, to make a collective effort to better understand and resolve the ongoing conflicts among the stakeholders and ultimately better serve our online students.
Relationship Between Ectopic HOXB4 Expression and Self-renewal in Normal and Leukemic Hematopoietic Cells
Keywords: Hematopoietic Stem Cells
HOXB4
Leukemia
Lineage-Restricted Progenitors
Retroviral Overexpression
Self-Renewal

Lifelong production of mature blood cells is mediated by long-term hematopoietic stem cells (LT-HSCs) which are capable of regenerating themselves through a process termed self-renewal. Importantly, it is the ability of LT-HSCs to sustain self-renewal that distinguishes them from other hematopoietic cells and enables them to long-term reconstitute all of the blood cells in recipient mice. Exogenous HOXB4 expression in primary bone marrow (BM) cells is currently understood to enhance the self-renewal of LT-HSCs and thus induce their expansion. However, the apparent expansion of LT-HSCs induced by HOXB4 may also be accounted for by alternative mechanisms that hinge on the acquisition of stem cell-like properties in non-LT-HSCs. In evaluating the effect of HOXB4 overexpression in purified cells further down the hematopoietic hierarchy, I found that HOXB4-transduced individual short-term HSCs (ST-HSCs) were capable of generating sustained primary grafts comprising only a subset of hematopoietic lineages. Lineage-restricted patterns of reconstitution were also observed when reconstituted BM from multilineage-engrafted primary recipients were limit diluted into secondary recipients. My results support a model in which multilineage reconstitution mediated by ectopic HOXB4 expression is maintained, in part or possibly exclusively, by lineage-restricted progenitor cells that have newly acquired the ability to sustain self-renewal by virtue of enforced HOXB4 expression. To determine if this endowment of sustained self-renewal potential represents a reprogramming phenomenon, I’ve also undertaken an investigation into the effect of withdrawing ectopic HOXB4 expression on long-term engraftment. My results reveal a dependency on continued HOXB4 expression for sustained self-renewal capacity suggesting active HOXB4 protein production is required for the permanence of the grafts generated by lineage-restricted progenitor cells. Finally, long-term follow-up of HOXB4-transduced cells uncovered a large number of leukemias developing in experimental animals. My work highlights the negative consequence of cells acquiring sustained self-renewal potential, and paves the way for future investigation into the importance of maintaining this self-renewal program in cancer development.
Computational Modeling and Analysis of Complex Muscle Architecture
Keywords: Cadaveric specimen
Digitization
Muscle architecture
PCSA
Skeletal muscle
Ultrasonography

Muscle architecture is a primary determinant of the muscle function associated with body movement. An assessment of muscle architecture is therefore of great importance, not only for investigating anatomical aspects of muscle but also for predicting its functional capacity. Most muscles have a variable complexity in their architectures, making it challenging to accurately assess them. Previous cadaveric approaches only take into account limited portions of architecture. On the other hand, conventional radiological approaches, such as ultrasonography and MRI, examine two-dimensional projected images. Neither of these approaches provides a thorough understanding of the entire muscle architecture. This may lead to under- or overestimation of architectural parameters that are signicant for both clinical and computational studies. Therefore, the purpose of this thesis is to develop a computational modeling approach to facilitate quantication and reconstruction of complex muscle architecture. Cadaveric specimen data are used to investigate muscle architecture and to reconstruct accurate models. Associated geometric complexity and variation are carefully examined to yield consistent estimation of architectural parameters. This method demonstrates robustness against non-uniformity in the data and consistency over various types of muscle architecture; less than 10% error in PCSA estimation. By incorporating ultrasonographic assessment, this method is extended to approximate muscle architecture in living subjects, which enables estimation of PCSA for in vivo muscle in a more consistent manner. Validation experiments demonstrate 0:4 􀀀 8:4 % estimation errors between the original architecture and its approximation, depending on the anatomical complexity, which provides a practical insight into the quantication of PCSA for in vivo muscle.
Azure
Keywords: landscape
orchestra
programme music
symphony
tonal
tone poem

Azure is a single-movement, through-composed work for large orchestra; its tense urgency nonetheless finds at its centre a stretch of utter calm. As I wrote Azure I wanted to explore what is vast. Its title refers to the blue of the sky, and also the sense of scale that “sky-blue” and “ocean-blue” evoke. Azure falls into four large sections followed by a dark coda. The opening gesture – repeating, monolithic tutti punches – gives way to an ostinato, around which the woodwinds, brass, and strings exchange small “call” figures, most importantly the recurring triplet-sixteenth motive, which carries through the entire work. Cross-fading major-minor triads become another important and recurring motive. Glissandi and other Doppler effects give a sense of vast space and then become siren-like, adding to the music’s martial atmosphere and growing urgency. The second large section is a slow waltz. After the towering chords return, the decay of the orchestra’s sound becomes an illustrated silence, time frozen as the players’ magnified breathing slowly gives way to a luminous C minor chord which hangs suspended as far as the ear can hear: music heard from a great height. Small, half-remembered gestures move glacially across this plane, and slowly the war-like atmosphere returns. But as the piece approaches its climax the opening chords do not reappear – instead, the tension evaporates into a coda much darker than anything that came before. Azure draws not only on many of the images and thematic interests that have come to govern my work, it also draws on my growing interest in time-distortion, pitch bending, Doppler effects, and the other features of a recognizable but disturbed tonal language that I find evocative. Azure may be sky-blue but this work is agitated and tense, offset by moments of gentle tranquility that are in themselves vast, timeless, and elemental.
Photonic Enhancement of Colloidal Quantum Dot Photovoltaics
Keywords: Colloidal Quantum Dots
Optoelectronics
Photonics
Photovoltaics

Colloidal quantum dots, nanocrystal semiconductors that can be cross-linked and assembled into absorbing thin films, are an attractive material for third-generation photovoltaic applications due to low-cost fabrication and bandgap tunability. As a result of their limited charge transport, these solution-processed thin films suffer from a mismatch in absorption length and charge extraction length. Concepts based on the interdigitation of n- and p-doped layers, approaches that reduce the distance photogenerated carriers must travel before extraction, offer promise on overcoming this limitation. In this thesis, I explore and develop techniques to address the absorption-extraction compromise in CQD materials by implementing nano- and micro-structuring techniques to enhance light absorption in the active film. First, I focus on the development of nanomaterials for light guiding/scattering enhancement in CQD films. For this, I develop a nanostructured gold reflector that, when suitably designed, guides light and traps it within the active film. I show that this yields enhanced broadband absorption with more than 4-fold improvement at the most improved wavelength, which translated into a 34% improvement in photocurrent in a working solar cell. I also show that periodic nanostructures employed for absorption enhancement can lead to improvements in solar cell performance. Limitations in device architecture and film formation, however, prevented significant performance advances for these nano-scale approaches. Regardless, these early results pointed me to a new and more impactful strategy. I focus in on realizing micron-scale structured electrodes to enhance absorption, which I show to be considerably more useful in view of the need to extract charge carriers with high efficiency. I discover that conformal film formation atop these structured electrodes is an absolute prerequisite to enhancing performance. These devices, which I term micro-pyramid CQD cells, provide a 24% enhancement in current and a consequent 15% improvement in power conversion efficiency. Ultimately, this work offers a prescription for photonic enhancements of solar cells within this emerging class of photovoltaic materials.
How Does Ontario Primary Care Perform? Effectiveness, Costs and Efficiency
Keywords: costs
efficiency
patient outcomes
performance measurement
primary care

In 2001, Ontario began introducing new primary care models characterized by physician remuneration mechanisms, interdisciplinary teams, access requirements, and patient enrolment. The objectives of the primary care reform were to improve the quality of and access to primary care and to make primary care more attractive as a physician specialty. This thesis explores the performance of the new primary care models – enhanced fee-for-service (FFS), blended capitation, and interdisciplinary teams - compared to the traditional FFS model. The effectiveness, costs and efficiency are reviewed separately in three distinct studies. The study about effectiveness aims to measure the risk of having a hospitalization for an ambulatory care sensitive condition (ACSC). The risk of having an ACSC hospitalization was lower for patients whose physician practiced in an enhanced-FFS or in a capitation model compared to patients whose saw a FFS physician. It was higher for patients who saw physicians who worked in interdisciplinary teams. The second study examined primary care costs and total health care costs for a randomly selected 10% sample of the Ontario adult population. The costs were calculated at the individual level based on the prices of the services and the utilization. Compared to patients of FFS physicians, patients in capitation models had higher primary care costs but lower total health care costs. Enhanced-FFS patients had the lowest primary care costs and total health care costs. The third study employed a Stochastic Frontier Analysis (SFA) to assess the efficiency of physicians. The analyses were supported by survey data on a physician’s hours worked on direct patient care, duration of the visits and other characteristics of a physician’s practice and linked to administrative data on patient visits. After controlling for input and explanatory variables, efficiency scores were on average higher for physicians in blended capitation models and in interdisciplinary teams compared to physicians in FFS. The three studies show significant differences across models for each of the outcomes examined (ACSC hospitalization; primary care costs and total health care costs; efficiency). More research is needed to understand these variations and the causal relationships in these variations, in order to better inform policy.
Characterizing Structural Changes of the Magnesium channel, CorA: Implications for Gating
Keywords: allosteric regulation
ion channel
Magnesium channel
pentameric protein
structural biology
X-ray crystallography

CorA is the primary magnesium channel in prokaryotes and the most extensively studied member of the CorA/Mrs2/Alr1 superfamily of magnesium channels that extends into eukaryotes. Existing crystallographic structures define the closed state of CorA and provide a structural basis for its structure-function relationships. However, detailed mechanisms of gating and ion permeation remain poorly understood. In this thesis, a combination of biochemical and biophysical methods were used to understand the molecular details involved in CorA gating. Specifically, dynamic structural elements involved in CorA gating were identified through limited proteolysis and mass spectrometry. Cysteine cross-linking along with mutagenesis assays show that the formation of an inter-protomer salt-bridge at the membrane-cytosol interface may be a key component of the activation mechanism. This ties in with the earlier limited proteolysis and mass spectrometry results indicating that the channel exposes its membrane-cytosol interface during gating. Finally, we report the first structural elucidation of the CorA soluble domain in a pentameric arrangement. The structure reveals significantly increased closure of the soluble domain funnel compared to the regular closed state, suggesting that the membrane domain can impose constraints on the soluble domain to resist the closing motion of the funnel triggered by Mg2+ binding. A model is proposed based on this observation, which may explain the mechanics underlying channel gating. Altogether, these studies have furthered the understanding of the molecular basis of CorA gating, particularly on the communication mechanism linking structural rearrangements in the soluble regulatory domain and the motion of the membrane domain. Furthermore, the results from this thesis agree with a sequential gating mechanism in which the channel undergoes asymmetric conformational changes.