VictorJuiz/thesis huggingface dataset:
Prognostic Factors in Aneurysmal Subarachnoid Hemorrhage: Pooled Analyses of Individual Patient Data and Development of Novel Risk Scores in Large Cohorts of International Patients

Primary studies reporting prognostic associations in aneurysmal subarachnoid hemorrhage (SAH) are often insufficiently powered, use data of limited representativeness and scarcely examine the added value of prognostic factors above those of other known factors. Hence, considerable knowledge gaps and conflicting results exist in the literature on the nature and extent of prognostic associations in SAH. Prognostic factors have been combined to develop prediction models and risk scores for early outcome prediction after SAH. None is routinely applied in clinical or research settings; some major constraints relate to lack of evidence on the predictive accuracy, reliability and generalizability of reported risk scores. The global aim of this research was to address these challenges and contribute to improved understanding of prognostic associations in SAH by analysing large cohorts of SAH patients reflecting a broad spectrum of settings. Pooled analyses of patient-level data from multiple randomized clinical trials and prospective hospital registries involving 10963 patients demonstrated a strong prognostic effect of admission neurologic status on 3-month outcome according to Glasgow outcome score. Age had a moderate effect on outcome; premorbid hypertension and subarachnoid clot burden on the Fisher scale were weak predictors of outcome. Patient's sex had no independent predictive value. Prognostic effect of aneurysm size and location depended on treatment modality. Novel prognostic scores were developed combining these predictors for early prediction of mortality and unfavorable outcomes at 3 months, and demonstrated adequate performance at bootstrap (AUC: 0.77 - 0.83) and at cross validation. Using 2 nationally representative administrative datasets, socioeconomic status and race/ethnicity were explored as latent prognostic factors in SAH. Multinomial logistic regression analysis demonstrated socioeconomic status, measured as neighborhood income status, was associated with inpatient mortality risk after admission for SAH. The extent of the association could be related to health care system under which treatment was provided. Race/ethnicity was independently associated with inpatient mortality. Patients of Hispanic ethnicity had the best outcomes and Asia/Pacific Islanders experienced the worst outcomes during the inpatient course. This research has provided higher level evidence than prior studies on studied prognostic factors and reliable tools for early prediction of outcome after hospitalization for SAH.

Keywords: Cerebrovascular
Clinical trial
Meta analysis
Outcomes
Risk factors
Subarachnoid hemorrhage
Advisor: Macdonald, Loch Robert
Integrating African Indigenous Science into the Faculties of Higher Education Curriculum in Uganda

This study examines African Indigenous Science (AIS) in higher education in Uganda. To achieve this, I use anticolonial theory and Indigenous knowledge discursive frameworks to situate the subjugation of Indigenous science from the education system within a colonial historical context. These theories allow for a critical examination of the intersection of power relations rooted in the politics of knowledge production, validation, and dissemination, and how this process has become a systemic and complex method of subjugating one knowledge system over the other. I also employ qualitative and autoethnographic research methodologies. Using a qualitative research method, I interviewed 10 students and 10 professors from two universities in Uganda. My research was guided by the following key questions: What is African Indigenous Science? What methodology would help us to indigenize science education in Uganda? How can we work with Indigenous knowledge and anticolonial theoretical discursive frameworks to understand and challenge the dominance of Eurocentric knowledge in mainstream education?My research findings revealed that AIS can be defined in multiple ways, in other words, there is no universal definition of AIS. However, there were some common elements that my participants talked about such as: (a) knowledge by Indigenous communities developed over a long period of time through a trial and error approach to respond to the social, economic and political challenges of their society. The science practices are generational and synergistic with other disciplines such as history, spirituality, sociology, anthropology, geography, and trade among others, (b) a cumulative practice of the use, interactions with and of biotic and abiotic organism in everyday life for the continued existence of a community in its' totality. The research findings also indicate that Indigenous science is largely lacking from Uganda's education curriculum because of the influence of colonial and post-colonial education. Graduates of the colonial education system who are manning education in the country have themselves come to disdain Indigenous knowledge. The major findings from the study were: 1) participants' articulation of Indigenous science; 2) influence of organized religion on African Indigenous Science; 3) dominance of professors' foreign experiences in determining curriculum content; 4) protection of intellectual property rights for Indigenous science; and 5) collaborative research between Indigenous and Western scholars to enhance attitude change toward Indigenous science.

Keywords: Anti-colonial education
Indigenous Science
Knowledge hybridization
Traditional Knowledge
Advisor: Wane, Nathani Njoki
The Genetic and Epigenetic Basis of Posterior Fossa Ependymoma

Ependymomas are childhood brain tumors that occur throughout the central nervous system, but are most common in the hindbrain, also known as the posterior fossa (PF). Current standard therapy comprises maximal safe surgery and radiation, but not cytotoxic chemotherapy as it does not further increase survival. Despite histological similarity, ependymomas from throughout the neuroaxis likely comprise multiple independent entities, each with a distinct molecular pathogenesis. Transcriptional profiling of two large independent cohorts of ependymoma reveals the existence of two demographically, transcriptionally, genetically, and clinically distinct groups of posterior fossa ependymomas, termed Group A and B. Group A patients are younger, have laterally located tumors with a balanced genome, and are much more likely to exhibit recurrence, metastasis at recurrence, and death as compared to Group B patients. In spite of balanced genomes observed in Group A PF ependymoma, whole-genome and whole-exome sequencing of 47 PF ependymomas reveals an extremely low mutation rate, and zero significant recurrent somatic single nucleotide variants (SNVs). While devoid of recurrent SNVs and focal copy number aberrations, poor prognosis Group A ependymomas exhibit a CpG island methylator phenotype (CIMP). Transcriptional silencing driven by CpG methylation converges exclusively on targets of the polycomb repressive complex 2 (PRC2) that represses expression of differentiation genes through tri-methylation of H3K27. Group A-CIMP+ PF ependymomas are responsive to clinical drugs that target either DNA or H3K27 methylation both in vitro and in vivo. We conclude that epigenetic modifiers are the first rational therapeutic candidates for this deadly malignancy, which is epigenetically de-regulated but genetically bland.

Keywords: Brain Tumor
Cancer
Ependymoma
Epigenetics
Genetics
Pediatrics
Advisor: Taylor, D Michael
Dynamic Thermo-mechanical Phase-field Models for Martensitic Transformations in Shape Memory Alloys

Shape memory alloys (SMAs) exhibit complex microstructures and non-linear hysteretic behaviors that arise from a strong interaction between mechanical and thermal phenomena. It is imperative to couple the thermal physics and the mechanical dynamics to study the influence of such coupling on the mechanical properties of SMA systems, including nanostructures. However, the majority of phase-field models in the literature related to SMAs account for structural physics only. With the aim to incorporate thermal physics, in this thesis, first the 2D and 3D dynamic fully coupled thermo-mechanical phase-field models are developed based on the strain-based order parameters. The developed models are highly nonlinear, strongly hysteretic with fourth-order spatial differential terms, which impose several computational challenges. Secondly, to overcome these computational challenges, a numerical formulation based on the isogeometric analysis is developed for a straightforward solution to the fourth-order differential equations using continuously differentiable non-uniform rational B-splines (NURBS).Several numerical examples of microstructure evolution in SMA systems, in particular nanostructures of different geometries, under temperature and stress induced loadings illustrated the flexibility, accuracy and robustness of the developed numerical formulation. The numerical simulations revealed a significant impact of the temperature dynamics on mechanical properties of SMAs. The developed models successfully captured experimentally observed mechanical and thermal hysteresis phenomena, local non-uniform phase transformations and corresponding non-uniform temperature and deformations distributions. The predicted microstructure evolution is in qualitative agreement with the results reported in the literature. The material properties of austenite and martensite phases are different, as observed experimentally during phase transformations. However, the majority of macroscale non-isothermal phase-field models in the literature related to SMAs account only for uniform material properties of different phases. Therefore, the new 1D and 3D macroscale non-isothermal phase-field models incorporating the phase dependent properties are developed in this thesis for a better description of hysteresis phenomena in SMAs. Specifically, the non-linear thermo-mechanical phase dependent material properties are incorporated via the compliance variable as a function of local scalar phase order parameter and stress state. The simplicity of the proposed 1D and 3D non-isothermal phase-field models allowed efficient numerical implementations.

Keywords: Isogeometric analysis
Martensitic transformations
Phase-field model
Shape memory alloys
Thermo-elasticity
Twinning
Advisor: Zu, Jean
Computing the Zeta Function of Two Classes of Singular Curves

Motivated by applications to cryptography, for over a decade mathematicians have successfully used p-adic cohomological methods to compute the zeta functions of various classes of varieties defined over finite fields. In all instances, the varieties considered had smooth representations in either affine or projective space.In this thesis, two non-smooth situations are introduced: the case of superelliptic curves with singular points that are rational over the field of definition, and the case of nodal projective plane curves. In each case we present, assuming the characteristic is fixed, a polynomial-time algorithm which computes the zeta function the curve, and we provide the results of an implementation in MAGMA. The case of singular superelliptic curves extends a method of Gaudry and Gurel, and the case of nodal projective curves extends a method of Kedlaya, Abbott, and Roe.

Keywords: cryptography
p-adic cohomology
point counting
singular varieties
zeta function
Advisor: Murty, Kumar
Femtosecond Electron Diffraction and Spectroscopic Studies of a Solid State Organic Chemical Reaction

Photochromic diarylethene molecules are excellent model systems for studying electrocyclic reactions, in addition to having important technological applications in optoelectronics. The photoinduced ring-closing reaction in a crystalline photochromic diarylethene derivative was fully resolved using the complementary techniques of transient absorption spectroscopy and femtosecond electron crystallography. These studies are detailed in this thesis, together with the associated technical developments which enabled them. Importantly, the time-resolved crystallographic investigation reported here represents a highly significant proof-of-principle experiment. It constitutes the first study directly probing the molecular structural changes associated with an organic chemical reaction with sub-picosecond temporal and atomic spatial resolution -- to follow the primary motions directing chemistry.In terms of technological development, the most important advance reported is the implementation of a radio frequency rebunching system capable of producing femtosecond electron pulses of exceptional brightness. The temporal resolution of this newly developed electron source was fully characterized using laser ponderomotive scattering, confirming a 435 +/- 75 fs instrument response time with 0.20 pC bunches. The ultrafast spectroscopic and crystallographic measurements were both achieved by exploiting the photoreversibility of diarylethene. The transient absorption study was first performed, after developing a novel robust acquisition scheme for thermally irreversible reactions in the solid state. It revealed the formation of an open-ring excited state intermediate, following photoexcitation of the open-ring isomer with an ultraviolet laser pulse, with a time constant of approximately 200 fs. The actual ring closing was found to occur from this intermediate with a time constant of 5.3 +/- 0.3 ps. The femtosecond diffraction measurements were then performed using multiple crystal orientations and a large number of different samples. To analyse the results, an innovative method was developed in which the apparently complex ring-closing reaction is distilled down to a small number of basic rotations. Immediately following photoexcitation, sub-picosecond structural changes associated with the formation of the intermediate are observed. The rotation of the thiophene rings is identified as the key motion. Subsequently, on the few picosecond time scale, the time-resolved diffraction patterns are observed to converge towards those associated with the closed-ring photoproduct. The formation of the closed-ring molecule is thus unambiguously witnessed.

Keywords: Crystallography
Diarylethene
Electron DIffraction
Solid State Organic Reaction
Transient Absorption Spectroscopy
Ultrafast
Advisor: Miller, R. J. Dwayne
Controlling the Near-wake of a Circular Cylinder with a Single, Large-scale Tripwire

Control of the flow past a circular cylinder using a single tripwire on its surface has been studied experimentally as a function of the wire angular location for different wire-to-cylinder diameter ratios (0.029

Keywords: circular cylinder
flow control
spanwise protrusion
tripwire
vortex shedding
Advisor: Ekmekci, Alis
Three Essays on the Individual, Task-, and Context-related Factors Influencing the Organizational Behaviour of Volunteers

This dissertation examines how various individual, task-, and context-related factors influence important volunteering outcomes. Using data sourced from a large international aid and development agency in the United Kingdom, the three studies that follow explore the organizational behaviour of volunteers and highlight several initiatives that nonprofit organizations can introduce in order to motivate and retain their volunteers.In the first chapter, I present a moderated mediation model where I show that prosocially motivated volunteers dedicate more time to volunteering. The study results further show that volunteer engagement fully mediates the relationship between the value motive and volunteer time, and that the strength of the mediated effect varies as a function of volunteers' commitment to beneficiaries. These findings provide a new perspective on the link between volunteers' motivation and active participation in volunteer activities.The second chapter presents a framework for understanding the processes through which volunteers' perceived impact on beneficiaries influences their turnover intentions and time spent volunteering. The results show that volunteers who perceive that their work impacts beneficiaries (1) report lower intentions to leave their volunteer organization due to their commitment to that organization; and (2) dedicate more time to volunteering because they are committed to the beneficiaries of their work. These findings make a significant contribution to volunteering research by uncovering two different mechanisms that explain how the positive consequences of perceived impact on beneficiaries may unfold.Finally, the third chapter presents a mediation model that explains how an organizational support framework promotes organizational commitment in volunteers. Specifically, the results show that training and paid staff support promote higher levels of volunteers' organizational commitment due to increases in volunteers' perceptions of role clarity and self-efficacy. Importantly, this study illustrates how volunteer managers can use two management practices that are under their control to maximize the commitment of volunteers.

Keywords: Nonprofit management
Volunteering
Advisor: Gunderson, Morley
Essays on Uniform Pricing and Vertical Contracts in Two-sided Markets

This thesis is comprised of three chapters linked together by their economic analysis of uniform pricing and vertical contracts in two-sided markets. Various forms of uniform pricing and vertical contracts are present in the United States cable television market (Chapter 1), markets involving online purchasing platforms (Chapter 2), and in markets for health insurance (Chapter 3). These markets are common examples of two-sided markets since, for example, local television stations connect advertisers and viewers, online platforms connect buyers and sellers of various goods, and health insurers connect patients with medical providers. This thesis studies the economic consequences of vertical contracts and uniform pricing practices, which can arise through private contract or government regulation, in two-sided markets. Chapter 1 examines how local television stations have responded to a regulation of the 1992 Cable Act mandating cable distributors offer consumers local content in the form of a bundle with a single price. In this chapter, I show that this form of government-mandated uniform pricing results in television stations setting their prices for content higher than they would absent this regulation. In collaboration with Kenneth Corts, Chapter 2 examines the pricing incentives of sellers who reach potential buyers through platforms that may restrict sellers to offering a uniform price across all platforms. This contractual restriction is commonly referred to as a ``most-favored-nation" clause. In this chapter, we show that platforms may find it privately profitable to adopt such a contractual restriction, and that the result is higher fees charged by platforms to sellers.Chapter 3 studies the use of most-favored-nation clauses in markets for health insurance. A health insurer may find it privately profitable to restrict its participating medical providers from discounting their medical services to rival insurers, which amounts to uniform pricing of medical services to insurers. In this chapter, I show that such uniform pricing may lead to lower prices for health insurance as any discounts offered to one insurer must also be extended to all other insurers.

Advisor: Corts, S. Kenneth
Rethinking Latin@ Student Engagement: Identification, Community Engagement, and Transformative Learning through Youth Participatory Action Research

My dissertation explores the ways in which youth participatory action research (YPAR) can provide students with the affective and the socio-educational experiences to become agents of personal, social, as well as educational change. My analysis is centred on a YPAR pilot study at Urban High School (pseudonym), a central Toronto secondary school with large numbers of students who self-identified as Latin@. This YPAR program, which was implemented as a Saturday senior social science credit course, involved 20 Latin@ students from diverse national, ethnic and academic backgrounds. Through a transnational Latin@ feminist lens and a methodological framework of YPAR, I examine how the students describe the processes of self-identification, community engagement, and transformative learning. While exploring the students' perspectives on their engagement and learning throughout the course, this dissertation problematizes conventional forms of schooling and argues for the necessity of shifting schooling towards more culturally relevant and student-centred pedagogies such as YPAR. The findings of this dissertation present YPAR as an alternative pedagogy that provides students with the opportunities to participate in collaborative learning environments through which they can develop knowledge as well as critically engage with issues that are relevant to them. In turn, this youth-centred pedagogy provides students with various forms of resources that create vast possibilities for transformative learning on individual and collective levels. Included in these possibilities is the building of relationships as well as critical dialogue on a variety of topics like power relations, gender, race, immigration, and schooling. The opportunities for such critical conversations cultivate a relevant context through which students can develop their research and inquiry skills and acquire a foundation through which to learn more about themselves and their social context. The dissertation concludes with an account of how this YPAR work has been expanded beyond the course and into further work with Latin@ and other groups of youth. This account points not only to the necessity of rethinking conventional forms of schooling, but also to the possibilities that YPAR yields for empowering youth to shift how they see themselves and engage with the world around them.

Keywords: Latina/o youth
participatory action research
secondary teaching and learning
transformative learning
Advisor: Gaztambide-Fernandez, Ruben
Copy Number Variation in Neurodevelopmental Disorders

Recent research on genetic etiologies of different neurodevelopmental conditions such as Autism Spectrum Disorder (ASD), Attention Deficit Hyperactivity Disorder (ADHD) and schizophrenia has highlighted a key role for rare copy number variants (CNVs). The study of such rare deletions and duplications in the genomes of patients has proven to be a powerful strategy for rapid identification of novel risk genes. Intriguingly, there is an emerging pattern of certain genes being implicated by rare CNVs across clinically distinct disorders. Findings of genetic overlap are consistent with comorbidity and shared traits often observed among these conditions and hint at common underlying biological processes or pathways such as synaptic development. This trend of overlapping genetic loci predisposing to different phenotypes has not been systematically investigated in an unbiased fashion on a genome-wide scale.In this thesis, I describe high resolution microarray analysis of three newly characterized Canadian cohorts of individuals with different neurodevelopmental disorders (ASD, ADHD and schizophrenia) in a uniform manner and with two main objectives. First, within each cohort, rare CNVs were detected and used to identify new genetic risk loci for each disorder. My prioritization strategy focused on rare CNVs of two types: those of

Keywords: ADHD
Autism
CNVs
Copy Number Variation
Microarrays
Schizophrenia
Advisor: Scherer, W Stephen