VictorJuiz/thesis huggingface dataset:
A New Family of Transformerless Modular DC-DC Converters for High Power Applications

This thesis presents a new family of converters for high power interconnection of dc buses with different voltage levels. Proposed converters achieve high voltage dc-dc conversion without an intermediate ac conversion stage. This function is implemented without series connection of active switches, or the use of isolation transformers. The salient features of proposed converters are (i) design and construction simplicity, (ii) low switching losses through soft turn-on and soft turn-off, (iii) single stage dc-dc conversion without high-current chopping, (iv) modular structure, (v) equal voltage sharing among the converter modules. Three converter circuits are investigated. The first performs unidirectional power transfer from a dc bus with higher voltage to a dc bus with lower voltage. The second performs unidirectional power transfer from a dc bus with lower voltage to a dc bus with higher voltage. Both converters are suitable for interconnecting single pole dc buses with same polarity, or double pole dc buses. A third converter is also presented which performs the function of either the first or the second converter with polarity reversal. The third converter is suitable for interconnecting single pole dc buses with different polarities, or double pole dc buses. By hybrid integration of the proposed three converters, the thesis also investigates other topologies for bidirectional power transfer between two dc buses. Proposed converters operate only in discontinuous conduction mode and exhibit soft switching operation for the active and passive switches. A common feature between the proposed converters is the self current turn-off for the active switches at zero voltage. This allows the use of thyristors as active switches alleviating their reverse recovery losses. For each converter topology, the structure is presented, its operation principle is explained and a complete set of design equations are derived. Comparisons are performed on high-power and high-voltage design examples. The merits and limitations of each converter are concluded. Practical considerations regarding components selection, loss analysis, filter design and the non-idealities of the circuits are studied. Experimental implementation of scaled-down laboratory prototypes is presented to provide a proof of concept and validate the operation principle of the proposed converter topologies.

Keywords: converters
power electronics
Advisor: Lehn, Peter W.
The Role of Homeodomain-interacting Protein Kinase (HIPK)-1 in B Lymphocytes

The homeodomain-interacting protein kinase (HIPK) family is comprised of four evolutionarily conserved and highly related serine/threonine kinases originally identified as co-repressors for homeodomain-containing transcription factors. While the HIPKs are most noted for regulation of apoptosis, proliferation and differentiation, I report a pleiotropic function of HIPK1 within the B cell lineage. Although lymphocyte development was normal within the thymus and bone marrow of HIPK1-deficient (HIPK1-/-) mice, the spleen exhibited a reduced number of transitional and follicular (FO) B cells, but with an increase in the marginal zone (MZ) B cell population. HIPK1-/- B cells exhibited impaired proliferation in response to B cell receptor (BCR) cross-linking in vitro; and immunization of HIPK1-/- mice with T-independent type 2 (TI-2) antigen resulted in a significantly impaired humoral response despite the expanded MZ B cell population. Immunization with T-dependent (TD) antigen resulted in a kinetically delayed response, with impaired affinity maturation. Identification of a kinase-substrate interaction between HIPK1 and the B cell adaptor 3BP2 suggests a potential context for HIPK1 function in BCR signaling. HIPK1-/- B cells were uniquely resistant to reactive oxygen species (ROS)-induced apoptosis, but equally susceptible to UV- and γ-irradiation compared to controls. In vitro class-switch recombination (CSR) assays revealed that HIPK1 is required for the negative regulation of CSR. HIPK1-/- B cell cultures harbored more viable cells, more switched cells, and elevated AID mRNA levels. The findings presented in this thesis demonstrate that HIPK1 is required for splenic B cell homeostasis and optimal BCR-responsiveness. In contrast, HIPK1 is also required for the negative regulation of CSR, possibly by mediating CSR-induced apoptosis.

Keywords: immunology
B lymphocytes
Advisor: Rottapel, Robert
Promoting Inclusion in Urban Contexts: Elementary Principal Leadership

The purpose of this study is to explore the strategies principals use to promote inclusion in their urban elementary schools. Data was collected from sixteen urban elementary school principals—who were identified as skilled at promoting inclusion—in Ontario, Canada. The thesis argues that inclusion is vital to ensuring social justice and combating the culture of positivism in the current educational context. As well, this thesis presents numerous strategies to promote inclusion with staff members, students, and parents. I also identify critical themes: the importance of principals teaching others, particularly teachers, about inclusion; how the principals in this study learned about inclusion; teachers as barriers to the promotion of inclusion; and the negative impact on principals who promoted inclusion. I conclude with the connection of inclusion with the concept of the public intellectual.

Keywords: Inclusive leadership
Advisor: Ryan, James
Creating Consensus: An Exploration of Two Pre-charge Diversion Programs in Canada

Over the last forty years, diversion of young offenders from the criminal justice system has been a part of youth justice policy in Canada. Over this period of time numerous research studies have examined the effectiveness of diversion programs. Many have had similar conclusions: diversion programs do not draw the majority of their participants from court bound populations. While the purpose of diversion was to limit state intervention into the lives of young people, it has instead served to extend the arm of the law by increasing state intervention for many young offenders. Yet, despite the evidence diversion policy and programs continue to garner broad based support. This research is an attempt to understand the popularity of diversion over time and explore the purposes, beyond that of a reduction in the use of youth court, that diversion serves. This research examines two police pre-charge diversion programs in Ontario, Canada. Diversion is explored from the perspective of the police that use and operate these programs as well as from the perspective of the young people processed in them.

Keywords: diversion
policing
youth justice
Advisor: Doob, Anthony N.
A Multiple Case Study Exploration of Undergraduate Subject Searching

Subject searching—seeking information with a subject or topic in mind—is often involved in carrying out undergraduate assignments such as term papers and research reports. It is also an important component of information literacy—the abilities and experiences of effectively finding and evaluating, and appropriately using, needed information—which universities hope to cultivate in undergraduates by the time they complete their degree programs. By exploring the subject searching of a small group of upper-level, academically successful undergraduates over a school year I sought to acquire a deeper understanding of the contexts and characteristics of their subject searching, and of the extent to which it was similar in quality to that of search and domain experts. Primary data sources for this study comprised subject searching diaries maintained by participants, and three online subject searches they demonstrated at the beginning, middle, and end of the study during which they talked aloud while I observed, followed by focused interviews. To explore the quality of study participants’ subject searching I looked for indications of advanced thinking in thoughts they spoke aloud during demonstration sessions relating to using strategy, evaluating, and creating personal understanding, which represent three of the most challenging and complex aspects of information literacy. Applying a layered interpretive process, I identified themes within several hundred instances of participants’ advanced thinking relating to these three information literacy elements, with evaluative themes occurring most often. I also noted three factors influencing the extent of similarity between the quality of participants’ advanced thinking and that of search and domain experts which reflected matters that tended to be i) pragmatic or principled, , ii) technical or conceptual, and iii) externally or internally focused. Filtered through these factors, participants’ instances of advanced thinking brought to mind three levels of subject searching abilities: the competent student, the search expert, and the domain expert. Although relatively few in number, I identified at least some advanced thinking evincing domain expert qualities in voiced thoughts of all but one participant, suggesting the gap between higher order thinking abilities of upper-level undergraduates and information literate individuals is not always dauntingly large.

Keywords: subject searching
information literacy
higher order thinking
upper level undergraduate students
Dean's Honour List students
Advisor: Howarth, Lynne C.
Sexual Risk Behavior, HIV, and Sexually Transmitted Infections in a Cohort of Kenyan Female Sex Workers, 1993 – 2007

This thesis comprises a detailed analysis of sexual risk behavior among female sex workers participating in a prospective cohort study in Mombasa, Kenya between 1993 and 2007. To determine whether high-risk behavior has decreased over time, I examined trends in and associations with condom use and partner numbers at enrolment and over follow-up using multinomial logistic regression. While condom use increased among women enrolling into the cohort, women reduced partner numbers, rather than increasing condom use, over cohort visits. Workplace, charge for sex, duration of sex work, alcohol use, pregnancy and illness were all predictors of condom use. To evaluate the extent to which HIV risk estimates were affected by loss to follow-up, I investigated associations between sexual risk behavior, loss to follow-up, and HIV acquisition, using competing risks regression. Women reporting unprotected sex with multiple partners had the highest risk for HIV infection, and were also most likely to remain in the cohort. Finally, I used Andersen-Gill modeling to assess the impact of sexual risk behaviors on acquisition of sexually transmitted infections (STI) including gonorrhea, non-specific cervicitis, and trichomoniasis. While incident gonorrhea was closely associated with recent sexual risk behavior, incident trichomoniasis was not. Both conditions had high hazards for recurring in a 90-day window after a prior diagnosis. Non-specific cervicitis was demonstrated to be a chronic, relapsing condition associated with protected sex with multiple partners (possibly due to more frequent condom use) and with known biologic risk factors (i.e., pregnancy, hormonal contraceptive use, cervical ectopy, and genital ulcer disease). Overall, these analyses have led to a better understanding of how different sexual behavior patterns are associated with adverse outcomes, including HIV and STI acquisition, and identified specific factors associated with high-risk sexual behavior that may be amenable to intervention.

Keywords: HIV
Sex work
Risk behavior
Sexually transmitted infections
Advisor: Bayoumi, Ahmed
Vitamin D Metabolites in Young Adults of Diverse Ancestry Living in the Greater Toronto Area

Vitamin D plays a critical role in bone metabolism and many cellular and immunological processes, and low vitamin D levels have been associated with several chronic and infectious diseases. Previous studies have reported that many otherwise healthy adults of European ancestry living in Canada have low vitamin D concentrations during the wintertime. However, individuals of non-European ancestry are at a higher risk of having low vitamin D levels. This thesis examined vitamin D status in a sample of young adults of diverse ancestry living in the Greater Toronto Area. In my research I found that: 1) vitamin D levels (measured as 25(OH)D concentrations) are low in Canadian young adults, particularly in those of non-European ancestry; 2) vitamin D intakes, which were estimated to be on average higher than current Health Canada recommendations of 200 International Units (IU) per day, were inadequate to maintain optimal vitamin D levels year-round; 3) vitamin D levels undergo large seasonal changes. Winter 25(OH)D concentrations are substantially lower than those observed during the fall; 4) vitamin D intake is an important year-round predictor of 25(OH)D concentrations, but skin pigmentation and sun exposure are also important predictors during the times when UVB is adequate for cutaneous synthesis; and 5) vitamin D binding protein (VDBP) polymorphisms are significant predictors of 25(OH)D concentrations, but their effects vary by ancestry and season, indicating gene-environment interaction effects. My research shows that higher vitamin D intakes are needed to offset the seasonal drop in vitamin D levels and to ensure adequate vitamin D levels year-round for those at higher risk of insufficiency.

Keywords: Vitamin D
Ancestry
Nutrition
Skin pigmentation
Seasonal
Advisor: Parra, Esteban J.
Instituting Market-based Principles within Social Services for People Living with Mental Illness: The Case of the Revised ODSP Employment Supports Policy

Policies are shaped by social values and assumptions, and can significantly impact the delivery of health and social services. Marginalized groups are often disadvantaged in the political realm and reliant on publicly funded services and supports. The purpose of this research is to consider how public policies are constructed and implemented for marginalized groups and to increase understanding of the consequences of policy reform. It draws on a case study of the Ontario Disability Support Program, Employment Supports (ODSP-ES) and considers the impact of the policy revision that occurred in 2006 on employment support services for people living with mental illness. A constructivist grounded theory approach guided data collection and analysis. Key policy documents were analyzed and 25 key informant interviews were conducted with individuals who were involved in: the construction and/or implementation of the policy; developing and/or delivering employment services under the policy; or advocacy work related to the policy. The findings highlight the impact of outcome-based funding on employment services and practices, and provide lessons for the construction and implementation of public policy for marginalized groups. The new funding system has promoted a shift from a traditional social service model of employment supports towards a marketing model, wherein services focus on increasing job placement and short-term job retention rates. However, the introduction of market principles into employment services has had significant implications for people living with mental illness. Employment programs are required to absorb increased financial risk, thereby altering the way service providers work with clients to help them find and keep jobs; there is a heightened focus on the rapid placement of clients into available jobs and less attention to the quality of employment being achieved and to complex barriers that prevent individuals from succeeding with employment. Although ODSP-ES has been somewhat successful at connecting people with disabilities to competitive employment, it has led to secondary consequences that compromise its overall utility. The findings highlight the complexity of constructing and implementing public policy for marginalized groups and suggest that evaluating public policy is an interpretative exercise that should be explored from multiple perspectives beyond the stated objectives.

Keywords: mental illness
qualitative research
employment supports
outcome-based funding
policy construction
policy implementation
disability policy
neoliberalism
Advisor: Kirsh, Bonnie
The Application of Cost-effectiveness Analysis in Developing Countries

Developing countries face imminent choices for introducing needed, effective but expensive new vaccines, given the substantial immunization resources now available from international donors. Cost-effectiveness analysis (CEA) is a tool that decision-makers can use for efficiently allocating expanding resources. However, although CEA has been increasingly applied in developing-country settings since the 1990’s, its use lags behind that in industrialized countries. This thesis explored how CEA could be made more relevant for decision-making in developing countries through 1) identifying the limitations for using CEA in developing countries 2) identifying guidelines for CEA specific to developing countries 3) identifying the impact of donor funding on CEA estimation 4) identifying areas for enhancement in the 1996 “Reference Case” (a standard set of methods) recommended by the US Panel on Cost-Effectiveness in Health and Medicine, and 5) better understanding the decision-making environment in developing countries. Focusing on pediatric immunization in developing countries, thematic analysis was used to distill key concepts from 157 documents spanning health economics, clinical epidemiology and health financing. 11 key informants, researchers active in developing countries, were also interviewed to explore the production and use of evidence in public health decision-making. Results showed a divergence between industrialized and developing nations in the emphases of methodological difficulties, in the general application of CEA, and the types of guidelines available. Explicitly considering donor funding costs and effects highlighted the need to specify an appropriate perspective and address policy-related issues of affordability and sustainability. Key informant interviews also revealed that opinion-makers, international organizations and the presence of local vaccine manufacturing have significant influence on decision-making. It is suggested that CEA could be more useful with a broadened reference case framework that included multiple perspectives, sensitivity analysis exploring differential discount rates (upper limits exceeding 10% for costs, declining from 3% for benefits) and supplemental reports to aid decision-making (budgetary and sustainability assessments). This study has implications for improving health outcomes globally in the context of public-private collaborative health funding. Further research could explore defining an extra-societal (multi-country) perspective to aid in efficient allocation of immunization resources among countries.

Keywords: economic evaluation
developing countries
immunization policy
Advisor: Ungar, Wendy Joan
An Automated Enrolment Projection System

From my own experience working in Institutional Research for the past seven years, there is not a proper, reliable, and comprehensive model for forecasting student enrolment quickly. In many funding formulas, enrolment is the main driver of government grants and student tuition fees, which are sources of income to the university. Existing enrolment management tools developed within Institutional Research departments tend to be “ad hoc” spreadsheets with multiple individuals manipulating them with the result that the output comes too late for departments to take remedial action in terms of their budgets and does not provide multiple scenarios in support of strategic decision-making. The purpose of this study is to describe a functional automated enrolment projection system methodology I developed from scratch through a case study of the Faculty of Arts & Science at the University of Toronto. My primary research was to actually build the model. The model in effect, is the thesis. The system provides multiple scenarios that allow senior management in a multi-campus university system to generate multiple income scenarios, enabling them to make well-informed decisions concerning the operation of their institution and timely calculation and allocation of resources to academic departments. The study then shows how this addresses the problems of “ad hoc” approaches, and how it may be applied in other situations.

Keywords: Enrolment Projection Model
Automated Enrolment Projection Model
Advisor: Lang, Daniel W.
The Right or Responsibility of Inspection: Social Work, Photography, and People with Intellectual Disabilities

Abstract The act of knowing is a critical determinant of what is known, yet there are limits and potential violence inherent in all ways of knowing. Social workers have an ethical responsibility to understand our means of knowing and our knowledge claims – both shape the work we do. Conspicuously under-represented as creators of/commentators on how they are represented, people with intellectual disabilities have had little/no control over what or how they are known. These ethical and epistemological concerns were the focus of this arts-informed qualitative study. The purpose was an interrogative encounter with one way of knowing – how public photographic imagery of people with intellectual disabilities influences knowledge about them. It was concerned, however, to come to this knowledge through an inquiry into how labelled people would, themselves, interpret and respond to these representations, and how they might use photography to trouble disabling images and non-disabled (social work) knowing. Theoretically framed by a critical disability lens, the work was influenced, too, by Derrida’s essay on photography, “The Right of Inspection”. The other regarding aspect of the philosophy of Emmanuel Levinas, his concern with our ethical responsibility to the alterity of the Other, most powerfully informs the work. Four adults with intellectual disabilities accepted the invitation to participate in this project. First, they critically engaged with a selection of public photographic images. In a unique methodological turn, they then transformed the images to reflect their critique. Interpretive analysis of the critiques and transformations identified four thematic ideas. Participants’ critiques were insightful and profound; transformations provocative and disruptive. Challenging dominant assumptions – and demanding non-disabled others re-think intellectual disability and people so labeled – the critiques and transformations also respond to the social/political/ideological/psychological ramifications of photographic imagery on the lived experience of intellectual disability. Through the work, participants confront non-disabled responses to public photographs and to labeled people, challenging non-disabled others to question their knowledge, attitudes, and behaviours. The work also raises questions about research and people with intellectual disabilities: the possibilities for voice and empowerment through inclusive research strategies and visual methodologies, and the transformative potential of dialogic encounters between people with and without intellectual disabilities.

Keywords: social work
intellectual disability
arts-informed research
photography and visual imagery
Advisor: Chambon, Adrienne S.