VictorJuiz/thesis huggingface dataset:
Vasculoprotective Effects of Insulin and Resveratrol In Vivo
Keywords: insulin
resveratrol
nitric oxide
restenosis

Atherosclerosis is a leading cause of morbidity and mortality worldwide and type 2 diabetes and obesity-associated metabolic syndrome, both characterized by insulin resistance, are potent risk factors. These conditions also increase the risk for restenosis after revascularization procedures used for treatment of atherosclerosis. Studies have shown that insulin and resveratrol (RSV), a red wine polyphenol, decrease neointimal growth after vessel injury in models of restenosis, demonstrating a protective effect on the vasculature. However, oral glucose and sucrose were used in insulin studies to maintain normoglycemia, and their effect on neointimal formation was not assessed. Several studies have shown that nitric oxide (NO) production is stimulated by insulin and RSV, and since NO can decrease neointimal growth, the objective of this thesis was to address the mechanism of action of insulin or RSV to protect against restenosis, and determine whether NO production mediates these effects. To examine this, we treated rats with insulin or RSV and performed arterial balloon injury. In Study 1, insulin reduced neointimal area after injury in rats receiving oral glucose but not oral sucrose. Oral glucose alone had no effect on neointimal formation or insulin sensitivity whereas oral sucrose increased neointimal growth and induced insulin resistance. In Study 2, insulin decreased neointimal area and cell migration, and increased re-endothelialization. These effects were abolished by nitric oxide synthase (NOS) inhibition. In addition, insulin increased eNOS protein expression in the vessel. In Study 3, RSV reduced neointimal growth, cell proliferation, and migration after injury, without affecting re-endothelialization. Most of these effects were abolished by NOS inhibition, except for the decrease in cell migration. Insulin sensitivity and systolic blood pressure were not affected by RSV. Together, the results demonstrate that insulin, independent of glycemic effects, and RSV have a protective effect on the vessel against restenosis, which is mediated by NO. Since both insulin and RSV decrease neointimal formation without negatively impacting re-endothelialization, insulin or RSV treatment could provide some advantage over anti-mitogenic agents currently used in drug-eluting stents, which delay re-endothelialization. These studies suggest that insulin or RSV may have clinical potential in the prevention of restenosis after angioplasty.
Multi-location Firms as a Medium for the Geographic Diffusion of Knowledge
Keywords: multinationals
innovation
knowledge
geography
diffusion

This thesis groups three papers examining the role of multi-location firms in the geographic diffusion of knowledge. The first chapter examines whether a firm's headquarters can tap into the knowledge pool in a remote location through FDI. Using U.S. patent data, I show that an R&D headquarters in location “A” cites third party patents from location “B” disproportionately (relative to a control group also from location “A”) when the firm has an R&D satellite in location “B”. This “satellite effect” on knowledge diffusion is economically significant, representing 47% of the knowledge flow premium associated with collocation. Furthermore, the effect is particularly strong for new knowledge, as well as in areas of satellite technological specialization. In addition, the results show that firms with stronger cross-location, intra-firm networks experience a larger satellite effect on knowledge diffusion. The second chapter studies the effects of remote satellites on outward knowledge flow with an international development focus. I find that the presence of a foreign MNC subsidiary increases the flow of knowledge from the MNC's headquarters to local firms. This effect is largest in countries and sectors with strong but not world-class capabilities, having both the motivation and absorptive capacity to learn from foreign parties. The results suggest that emerging country governments should promote inward FDI since the knowledge brought by multinationals spills over to local firms and boosts innovative capacity. The third chapter offers a theoretical foundation for thinking about the exchange of knowledge and ideas, and the role of remote satellites. I present a model where ideas are shared through social networks as modeled by repeated agent interactions. The mechanism at once explains three broad empirical findings: why the diffusion of ideas is highly localized, why ideas flow more easily within the firm, and why firms can access remote knowledge by establishing a presence in the remote location. A firm endogenously decides whether to establish a presence in a remote location and if so how much autonomy to award the remote agent. The relative importance of external vs. internal knowledge in the innovative process is a key determinant of the firm's organizational structure.
Creating Space for Students' Mother Tongues in College Classrooms: A Collaborative Investigation of Process and Outcomes
Keywords: Second Language Education
Mother Tongue

This study is a qualitative action research that I have undertaken with four teachers in the college where I work, for the purpose of improving curriculum delivery and student services to our majority multilingual student body. Based on my research in a public school board with Grades 4 to 12 students where I learned that mother tongues (L1s) are valued by students as scaffolds to their learning of English (L2) I proceeded to explore L1/L2 curriculum delivery with adult community college students whose prior learning is encoded in their mother tongues. I explored the possibility of legitimizing the use of students’ mother tongues in college classrooms as scaffolds to their acquisition of their L2. There were three phases to this study. Through these three phases of the study I sought to understand the impact of this multilingual pedagogical approach on the students’ learning experience, academic engagement and identity formation. In phase 1, I worked with 90 English as a Second Language (ESL) students whom I surveyed to determine their levels of understanding of our English-only curriculum delivery and student services. In phase 2, I worked with three English for Academic Purposes (EAP) students and interviewed them to explore their reaction to their teacher’s allowing them to use their mother tongues in class as part of pedagogy. In phase 3, I worked with 19 EAP students and interviewed them in focus groups to explore more deeply their learning experience, academic engagement and identity formation in two college classrooms where their mother tongues were part of everyday pedagogy. On the basis of the findings of this study I argue that the creation of space for students’ mother tongues in college classrooms is an ethical imperative since their mother tongues are integral components of their identities and all of their prior learning and life experiences are encoded in their mother tongues. Overall the findings highlighted bilingual students’ perceptions that their L1s constituted an important scaffold for their learning of English. Students’ comments also expressed their sense of the centrality of L1s to aspects of their identity.
Pattern Rules, Patterns, and Graphs: Analyzing Grade 6 Students' Learning of Linear Functions through the Processes of Webbing, Situated Abstractions, and Convergent Conceptual Change
Keywords: Elementary Mathematics Education
Patterning and Early Algebra
Linear Relationships

The purpose of this study, based on the third year of a three-year research study, was to examine Grade 6 students’ previously developed abilities to integrate their understanding of geometric growing patterns with graphic representations as a means of further developing their conception of linear relationships. In addition, I included an investigation to determine whether the students’ understanding of linear relationships of positive values could be extended to support their understanding of negative numbers. The theoretical approach to the microgenetic analyses I conducted is based on Noss & Hoyles’ notion of situated abstractions, which can be defined as the development of successive approximation of formal mathematical knowledge in individuals. I also looked to Roschelle’s work on collaborative conceptual change, which allowed me to examine and document successive mathematical abstractions at a whole-class level. I documented in detail the development of ten grade 6 students’ understanding of linear relationships as they engaged in seven experimental lessons. The results show that these learners were all able to grasp the connections among multiple representations of linear relationships. The students were also able to use their grasp of pattern sequences, graphs and tables of value to work out how to operate with negative numbers, both as the multiplier and as the additive constant. As a contribution to research methodology, the use of two analytical frameworks provides a model of how frameworks can be used to make sense of data and in particular to pinpoint the interplay between individual and collective actions and understanding.
Toward Multiplexed Nucleic Acid Assays and Biosensors Using Immobilized Quantum Dots as Donors in Fluorescence Resonance Energy Transfer (FRET)
Keywords: quantum dots
fluorescence resonance energy transfer
nucleic acids
biosensor
immobilization
assay

Research toward a multiplexed nucleic acid biosensor that uses quantum dots (QDs) as donors in a fluorescence resonance energy transfer (FRET) assay is described. Optical fibers were modified with mixed films composed of different colours of QDs and different oligonucleotide probes that served as scaffolds for the hybridization of the corresponding target nucleic acid sequences. Fluorescent dyes that were suitable as acceptors for each QD donor were associated with hybridization and provided an analytical signal through FRET-sensitized emission. Different detection channels were achieved through the combination of different donors and acceptors: green emitting QDs with Cyanine 3 or Rhodamine Red-X; and red emitting QDs with Alexa Fluor 647. A detection channel that used the direct excitation of Pacific Blue complemented the FRET pairs. One-plex, two-plex, three-plex and four-plex hybridization assays were demonstrated. A sandwich assay format was adopted to avoid target labeling. Detection limits were 1-10 nM (1-12 pmol) and analysis times were 1-4 h. Single nucleotide polymorphisms were discriminated in multiplexed assays, and the potential for reusability was also demonstrated. Non-selective interactions between QDs and oligonucleotides were characterized, and routes toward the optimization of the QD-FRET hybridization assays were identified. A basic model for multiple FRET pathways in a mixed film was also developed. In addition to the advantages of solid-phase assays, the combination of QDs and FRET was advantageous because it permitted multiplexed detection using a single excitation source and a single substrate, in the ensemble, and via ratiometric signals. Spatial registration or sorting methods, imaging or spatial scanning, and single molecule spectroscopy were not required. The research in this thesis is expected to enable new chip-based biosensors in the future, and is an original contribution to both bioanalytical spectroscopy and the bioanalytical applications of nanomaterials.
Black Focused Schools in Toronto: What do African-Canadian Parents Say?
Keywords: afrocentric education
black youth
race
parental choice
alternative schools
African-Canadian community

Abstract The purpose of this study was to examine how parents of African descent understand the African-centered school concept as an alternative education to the mainstream public school in Toronto. While we cannot ignore the success stories of some Black students in the school system, the reality remains that the academic performance of some shows a downward trend. Hence, concerned educators and members of the African-Canadian community suggest the need for the establishment of a Black focused or African-centered school as an alternative to the mainstream public school. This will allow students to learn more effectively because they are culturally grounded and will be able to link issues of individual or group identities with what goes on at school. This qualitative research relied principally on in-depth interviews with twenty African-Canadian parents who have children in the mainstream public schools in Toronto. It assumes that parents are important stakeholders in their children’s education so their views on problems and the need for an alternative form of schooling have significant implications for the academic performance of Black youth. The data from my study and available literature make it evident that despite the introduction of African heritage and multicultural programs and anti-racist education, profound problems still exist for Black youth in the mainstream public schools. The findings indicate that out of twenty, a majority of seventeen African-Canadian parents support the establishment of African-centered schools as an alternative to the mainstream public school. All participants interviewed agree that discrimination, prejudice and stereotyping in mainstream public schools are major problems for their children. The parents’ narratives show that the establishment of an African-centered school as an alternative to the mainstream public school is a way to combat the discrimination and prejudice Black youth encounter at school. The parents believe Black focused schools should be a major preoccupation of educational personnel, school boards and policy makers. Finally the implications of establishing an African-centered school to address the needs of Black youth and directions for future research are discussed.
Theoretical Investigation of Thermodiffusion (Soret Effect) in Multicomponent Mixtures
Keywords: Thermodiffusion
Soret Effect
Separation ratio
Convection
Permeability
PC-SAFT

Thermodiffusion is one of the mechanisms in transport phenomena in which molecules are transported in a multicomponent mixture driven by temperature gradients. Thermodiffusion in associating mixtures presents a larger degree of complexity than non-associating mixtures, since the direction of flow in associating mixtures may change with variations in composition and temperature. In this study a new activation energy model is proposed for predicting the ratio of evaporation energy to activation energy. The new model has been implemented for prediction of thermodiffusion for acetone-water, ethanol-water and isopropanol-water mixtures. In particular, a sign change in the thermodiffusion factor for associating mixtures has been predicted, which is a major step forward in modeling of thermodiffusion for associating mixtures. In addition, a new model for the prediction of thermodiffusion coefficients for linear chain hydrocarbon binary mixtures is proposed using the theory of irreversible thermodynamics and a kinetics approach. The model predicts the net amount of heat transported based on an available volume for each molecule. This model has been found to be the most reliable and represents a significant improvement over the earlier models. Also a new approach to predicting the Soret coefficient in binary mixtures of linear chain and aromatic hydrocarbons using the thermodynamics of irreversible processes is presented. This approach is based on a free volume theory which explains the diffusivity in diffusion-limited systems. The proposed model combined with the Shukla and Firoozabadi model has been applied to predict the Soret coefficient for binary mixtures of toluene and n-hexane, and benzene and n-heptane. Comparisons of theoretical results with experimental data show a good agreement. The proposed model has also been applied to estimate thermodiffusion coefficients of binary mixtures of n-butane & carbon dioxide and n-dodecane & carbon dioxide at different temperature. The results have also been incorporated into CFD software FLUENT for 3-dimensional simulations of thermodiffusion and convection in porous media. The predictions show the thermodiffuison phenomenon is dominant at low permeabilities (0.0001 to 0.01), but as the permeability increases convection plays an important role in establishing a concentration distribution. Finally, the activation energy in Eyring’s viscosity theory is examined for associating mixtures. Several methods are used to estimate the activation energy of pure components and then extended to mixtures of linear hydrocarbon chains. The activation energy model based on alternative forms of Eyring’s viscosity theory is implemented to estimate the thermodiffusion coefficient for hydrocarbon binary mixtures. Comparisons of theoretical results with the available thermodiffusion coefficient data have shown a good performance of the activation energy model.
The Strong Interactions, Flavour Physics and Beyond
Keywords: QCD
Flavour Physics

In this thesis we use effective field theories of the strong interactions to improve our understanding of several quantities in the Standard Model of particle physics (SM). We also examine constraints on an extension of the SM scalar sector and study the implications for the Higgs mass. We first examine an approach to extracting the Cabibbo-Kobayashi-Maskawa matrix element |Vub| via the relationship between the B meson decays B -> Xu l nu and B -> Xs gamma, where Xi is any final state hadron containing a quark of flavour i. Model dependence is reduced in this approach since the non-perturbative shape function at leading order is universal and drops out; however the perturbative expansion at next-to-leading order is found to be poorly behaved. We carry out a renormalon analysis of the relationship between these spectra to examine higher order perturbative corrections and compare the fixed-order and log expansions. Our analysis can be used to estimate the perturbative uncertainty in the extraction of |Vub|, which we show to be relatively small. Next we take a step towards the broader goal of summing large phase space logarithms from a variety of jet algorithms using Soft Collinear Effective Theory (SCET). We develop a consistent approach to implementing arbitrary phase space constraints in SCET and demonstrate the connection between cutoffs in SCET and phase space limits. By considering several jet algorithms at next-to-leading order, we gain some insight into factorization of final state jets. In particular, we point out the connection between the ultraviolet regulator and factorization. Finally we consider a scalar sector that contains a colour-octet electroweak-doublet scalar, in addition to the SM Higgs. This extension contains the only scalar representations that Yukawa-couple to quarks and are consistent with minimal flavour violation. We examine constraints from electroweak precision data, direct production from LEPII and the Tevatron, and from flavour physics. We find both the Higgs and new scalars can be simultaneously light, with masses of O(100 GeV). The data also allows all the scalars to be heavy, with masses of O(1 TeV). The presence of the additional scalars removes the preference for a light Higgs, which normally emerges from fits to electroweak precision data.
L-functions in Number Theory
Keywords: L-functions
modular forms

As a generalization of the Riemann zeta function, L-function has become one of the central objects in Number Theory. The theory of L-functions, which produces a large family of consequences and conjectures in a unified way, concerns their zeros and poles, functional equations, special values and the connections between objects in different fields. Although most generalizations are largely conjectural, there are many existing results that provide us the evidence. In this thesis, we shall consider some L-functions and look into some problems mentioned above. More explicitly, for the L-functions associated to newforms of fixed square-free level, we will consider an average version of the fourth moments problem. The final bound is proven by considering definite rational quaternion algebras and divisor functions in them, generalizing Maass Correspondence Theorem and one of Duke's results and eventually applying the solution to Basis Problem. We then consider the problem of expressing the central value at ½ of the Rankin-Selberg L-function associated to two newforms in terms of the Pertersson inner product, where one of the newforms is twisted by the derivative of some Eisenstein series. Finally, we consider the Artin L-functions attached to irreducible 4-dimensional S5-Galois representations and deal with the modularity problem. One sufficient condition on the modularity is given, which may help to find an affirmative example for Strong Artin Conjecture in this case.
Genomic Rearrangements in Human and Mouse and their Contribution to the Williams-Beuren Syndrome Phenotype
Keywords: Williams-Beuren Syndrome
Mouse Models
genomic rearrangement
Transcription Factor
anxiety
aggression

Genomic rearrangements, particularly deletions and duplications, are known to cause many genetic disorders. The chromosome 7q11.23 region in humans is prone to recurrent chromosomal rearrangement, due to the presence of low copy repeats that promote non-allelic homologous recombination. The most well characterized rearrangement of 7q11.23 is a hemizygous 1.5 million base pair (Mb) deletion spanning more than 25 genes. This deletion causes Williams-Beuren Syndrome (WBS; OMIM 194050), a multisystem developmental disorder with distinctive physical and behavioural features. Other rearrangements of the region lead to phenotypes distinct from that of WBS. Here we describe the first individual identified with duplication of the same 1.5 Mb region, resulting in severe impairment of expressive language, in striking contrast to people with WBS who have relatively well preserved language skills. We also describe the identification of a new gene for a severe form of childhood epilepsy through the analysis of individuals with deletions on chromosome 7 that extend beyond the boundaries typical for WBS. This gene, MAGI2, is part of the large protein scaffold at the post-synaptic membrane and provides a new avenue of research into both the molecular basis of infantile spasms and the development of effective therapies. Individuals with smaller than typical deletions of 7q11.23 have delineated a minimal critical region for WBS and have implicated two members of the TFII-I transcription factor family. To better understand the contribution of these genes to WBS, I have generated animal models with these genes deleted singly and in combination. Disruption of the first gene, Gtf2ird1, resulted in phenotypes reminiscent of WBS including alterations in social behaviour, natural fear response and anxiety. An alteration in serotonin function was identified in the frontal cortex and may be linked to these behavioural phenotypes. Together with a model for the second gene, Gtf2i, and the double deletion model that was generated using Cre-loxP technology, these resources will permit the study of the individual and additive effects of hemizygosity for Gtf2i and Gtf2ird1 and will greatly expand our understanding of the role the TFII-I gene family in WBS.