VictorJuiz/thesis huggingface dataset:
The Effect of Ion Energy and Substrate Temperature on Deuterium Trapping in Tungsten
Keywords: Deuterium Retention
Plasma Materials Interactions

Tungsten is a candidate plasma facing material for next generation magnetic fusion devices such as ITER and there are major operational and safety issues associated with hydrogen (tritium) retention in plasma facing components. An ion gun was used to simulate plasmamaterial interactions under various conditions in order to study hydrogen retention characteristics of tungsten thus enabling better predictions of hydrogen retention in ITER. Thermal Desorption Spectroscopy (TDS) was used to measure deuterium retention from ion irradiation while modelling of TDS spectra with the Tritium Migration Analysis Program (TMAP) was used to provide information about the trapping mechanisms involved in deuterium retention in tungsten. X-ray Photoelectron Spectroscopy (XPS) and Secondary Ion Mass Spectrometry (SIMS) were used to determine the depth resolved composition of specimens used for irradiation experiments. Carbon and oxygen atoms will be among the most common contaminants within ITER. C and O contamination in polycrystalline tungsten (PCW) specimens even at low levels (~0.1%) was shown to reduce deuterium retention by preventing diffusion of deuterium into the bulk of the specimen. This diffusion barrier was also responsible for the inhibition of blister formation during irradiations at 500 K. These observations may provide possible mitigation techniques for iii problems associated with tritium retention and mechanical damage to plasma facing components caused by hydrogen implantation. Deuterium trapping in PCW and single crystal tungsten (SCW) was studied as a function of ion energy and substrate temperature. Deuterium retention was shown to decrease with decreasing ion energy below 100 eV/D+. Irradiation of tungsten specimens with 10 eV/D+ ions was shown to retain up to an order of magnitude less deuterium than irradiation with 500 eV/D+ ions. Furthermore, the retention mechanism for deuterium was shown to be consistent across the entire energy range studied (10-500 eV) with the shallow penetration depth of low energy ions being the major factor in the reduction in retention. A change in retention mechanism was observed as tungsten temperature during irradiation was increased from 300 to 500 K. Modelling of deuterium retention in 300 and 500 K SCW specimens revealed that two traps, 1.0 and 1.3 eV, are involved in retention for irradiations performed at 300K while a single 2.1 eV trap is present for 500 K irradiations. Experiments suggest that the 2.1 eV trap is created during irradiation of tungsten at 500 K and this process also involves the annihilation of the 1.3 and 1.0 eV traps.
Meeting Women’s Health Needs in the Community: Assessment of the Physical Activity and Health Promotion Practices, Preferences and Priorities of Older Women Living with Cardiovascular Disease
Keywords: women
cardiovascular disease
health
physical activity
exercise
cardiac rehabilitation

Cardiovascular disease (CVD) is the leading cause of death among Canadian women, and accounts for up to 30% of deaths among women worldwide. Women with CVD are typically older than their male counterparts, experience worse functional status, are more likely to experience non-CVD health conditions such as diabetes or arthritis, and will live with these health conditions for more years than men. Physical activity (PA) and cardiac rehabilitation (CR) participation is lower among women compared to men, but little is known about the PA and health promotion experiences, priorities and practices of older women living with CVD. Guided by a socioenvironmental approach to health promotion, a mixed method design involving a mail survey (N=127) and qualitative interviews (N=15) was employed to describe and explore the PA and health promotion practices, preferences and priorities of older women (≥65 years) living with CVD in the Champlain health region of Ontario. Nearly 60% of survey respondents were referred to CR. Logistic regression analysis revealed urban residence as a predictor of CR referral (p<0.01, OR=3.24; 95% CI: 1.44-7.30). Nearly 55% of respondents attended CR, which was predicted by CR referral (p<0.01, OR=32.26; 95% CI: 9.26-111.11), availability of transportation (p<0.05, OR=9.96; 95% CI: 1.22-81.41), and a history of structured PA (p<0.05, OR=3.64; 95% CI: 1.16-11.36). Respondents were more active than their peers, but received little support from their physician for PA. Older women’s incidental PA (walking six or more hours/week for transportation) was predicted by their sense of community belonging (p<0.05, OR=2.6; 95% CI: 1.05-6.29) and having energy for PA (p<0.05, OR=5.8; 95% CI: 1.21-27.92). Interview participants (including four who had attended CR) described health as a resource that enables them to lead busy, active lives. Most participants attributed CVD to genetics or stress, but still engaged in health-promoting activities, including structured and incidental PA. Participants engaged in ‘incidental’ activities such as walking, gardening, and housekeeping tasks purposefully, with the intention of maintaining or improving their health. This research can inform public health initiatives and health care services (including CR) to better meet the needs and preferences of the growing population of older women with CVD.
Maximal-in-time Behavior of Deterministic and Stochastic Dispersive Partial Differential Equations
Keywords: dispersive partial differential equations
blow-up solutions
invariant measures
stochastic partial differential equations

This thesis contributes towards the maximal-in-time well-posedness theory of three nonlinear dispersive partial differential equations (PDEs). We are interested in questions that extend beyond the usual well-posedness theory: what is the ultimate fate of solutions? How does Hamiltonian structure influence PDE dynamics? How does randomness, within the PDE or the initial data, interact with well-posedness of the Cauchy problem? The first topic of this thesis is the analysis of blow-up solutions to the elliptic-elliptic Davey-Stewartson system, which appears in the description of surface water waves. We prove a mass concentration property for H^1-solutions, analogous to the one known for the L^2-critical nonlinear Schrodinger equation. We also prove a mass concentration result for L^2-solutions. The second topic of this thesis is the invariance of the Gibbs measure for the (gauge transformed) periodic quartic KdV equation. The Gibbs measure is a probability measure supported on H^s for s<1/2, and local solutions to the quartic KdV cannot be obtained below H^{1/2} by using the standard fixed point method. We exhibit nonlinear smoothing when the initial data are randomized, and establish almost sure local well-posedness for the (gauge transformed) quartic KdV below H^{1/2}. Then, using the invariance of the Gibbs measure for the finite-dimensional system of ODEs given by projection onto the first N>0 modes of the trigonometric basis, we extend the local solutions of the (gauge transformed) quartic KdV to global solutions, and prove the invariance of the Gibbs measure under the flow. Inverting the gauge, we establish almost sure global well-posedness of the (ungauged) periodic quartic KdV below H^{1/2}. The third topic of this thesis is well-posedness of the stochastic KdV-Burgers equation. This equation is studied as a toy model for the stochastic Burgers equation, which appears in the description of a randomly growing interface. We are interested in rigorously proving the invariance of white noise for the stochastic KdV-Burgers equation. This thesis provides a result in this direction: after smoothing the additive noise (by a fractional derivative), we establish (almost sure) local well-posedness of the stochastic KdV-Burgers equation with white noise as initial data. We also prove a global well-posedness result under an additional smoothing of the noise.
Iterative Reconstruction Algorithms for Polyenergetic X-ray Computerized Tomography
Keywords: Polyenergetic Iterative Reconstruction Algorithms
X-Ray Computerized Tomography (CT)
Beam hardening
Levenberg-Marquardt-Fletcher method

A reconstruction algorithm in computerized tomography is a procedure for reconstructing the attenuation coefficientscient, a real-valued function associated with the object of interest, from the measured projection data. Generally speaking, reconstruction algorithms in CT fall into two categories: direct, e.g., filtered back-projection (FBP), or iterative. In this thesis, we discuss a new fast matrix-free iterative reconstruction method based on a polyenergetic model. While most modern x-ray CT scanners rely on the well-known filtered back-projection algorithm, the corresponding reconstructions can be corrupted by beam hardening artifacts. These artifacts arise from the unrealistic physical assumption of monoenergetic x-ray beams. In this thesis, to compensate, we use an alternative model that accounts for differential absorption of polyenergetic x-ray photons and discretize it directly. We do not assume any prior knowledge about the physical properties of the scanned object. We study and implement different solvers and nonlinear unconstrained optimization methods, such as a Newton-like method and an extension of the Levenberg-Marquardt-Fletcher algorithm. We explain how we can use the structure of the Radon matrix and the properties of FBP to make our method matrix-free and fast. Finally, we discuss how we regularize our problem by applying different regularization methods, such as Tikhonov and regularization in the 1-norm. We present numerical reconstructions based on the associated nonlinear discrete formulation incorporating various iterative optimization methods.
Prejudice at the Intersection of Ambiguous and Obvious Groups: The Case of the Gay Black Man
Keywords: prejudice
stereotyping
cross-categorization
face perception
ambiguity

We often think of stigmatized individuals as encountering only one stereotype set at a time. Yet, many individuals belong to multiple stigmatized groups, and stereotypes associated with these groups jointly influence how perceivers evaluate targets. Research suggests that perceivers integrate stereotypes about targets’ obvious identities during impression formation; however, no work has examined whether targets’ obvious (e.g., race) and ambiguous (e.g., sexual orientation) identities jointly influence impressions. Given that gay stereotypes are activated automatically, I expected the co-activation of contradictory Black (e.g., aggressive) and gay (e.g., warm) stereotypes to arouse conflict, weakening activation of negative stereotypes and improving evaluations of Black gay targets compared with Black straight targets. Participants in Study 1 rated faces of White straight men as more likable than White gay men, but rated Black gay men as more likable than Black straight men. Participants in Study 2 performed a race-categorization task designed to make race salient; nevertheless, sexual orientation still influenced impressions, producing a pattern similar to Study 1. Participants in Studies 3A (approach-avoidance task) and 3B (evaluative priming task) formed implicit impressions that converged with the explicit evaluations in Studies 1 and 2. In 3A, participants approaching Whites responded faster to straights than gays, whereas participants approaching Blacks responded faster to gays than straights. In 3B, participants recognized positive words somewhat (but not significantly) faster when primed with White straight (versus White gay) and Black gay (versus Black straight) faces. Studies 4A – C suggest that ambiguous categories modify the activation of obvious stereotypes, but do not make targets’ features look less prototypical of their obvious groups. In 4B, participants were slower to recognize Black-stereotypic words (piloted in 4A) when primed with Black gay (versus Black straight) faces. In 4C, participants rated Black straight and gay faces as similarly prototypical of Black phenotypes. Taken together, this work presents implications for stereotyping in the case of multiply-categorizable targets and for impression formation involving ambiguous categories.
‘Lit For Life’: Using Literacy Intervention to Foster Meaningful Life Changes for High-risk Youth with Reading Disabilities
Keywords: literacy
maltreatment
adolescents
intervention
reading
writing
self-perception
disability

Substantial evidence indicates that maltreatment places abused children at great risk for illiteracy and damaging self-perceptions of competency and worth. Given that academic ability and self-concept are reciprocally related and mutually reinforcing, it was hypothesized that participation in an intensive literacy intervention would positively impact the reading, writing, and related self-perceptions of maltreated Struggling Readers from the Ontario Child-Welfare system. Using a mixed methods approach, 24 participants (ages 14-24) completed achievement and self-perception measures and were interviewed about their literacy experiences and views, pre and post intervention. Repeated measures analyses and pairwise comparisons measured the impact of intervention on the literacy skills and related self-evaluations of these youth and assessed how the literacy skills and related self-evaluations differed from maltreated youth without reading difficulties (n = 22). Interviews were analyzed thematically. Results converged to provide empirical support for the benefits of literacy intervention on skill and self-perception development for this high risk group of youth. Qualitative analyses further revealed unanticipated, dramatic and meaningful life changes. Participants manifested improved communication and metacognitive skills, increased autonomy and internal motivation, and amplified feelings of empowerment and hope for the future.
African/Caribbean-Canadian Women Coping with Divorce: Family Perspectives
Keywords: African
Caribbean
African-Canadian
Caribbean-Canadian
Black women
Women
Divorce
Coping
Separation
Family
Autoethnography
Case Study
Qualitative Research
Family Group Research
Grounded Theory
Caribbean-Canadian Women
Black Feminist Thought
Black Feminism
Family influence

In this dissertation, African/Caribbean-Canadian women’s experiences of coping with divorce were explored using a qualitative methodology. This study was approached from a Black Feminist paradigm using the lived experiences of Black women as a source of knowledge. Divorce and coping literature provided a theoretical framework for understanding the issues related to divorce in the Black community and effective coping efforts among Black women, particularly as it pertains to divorce. Six separated/divorced women from the same family, representing two generations, were interviewed individually and as a group using a semi-structured interview guide. The participants discussed their reflections on marriage and marital disruption, their post-separation experiences and challenges, and the coping resources they accessed during the divorce process. The participants also discussed how their own marriages and divorces were influenced by the marriages and marital disruptions of their family members. The results from the interviews were reported in a case study format using the voices of the participants to tell their own stories. A grounded theory analysis found that Black women faced the common challenges of starting over, single parenting, financial loss, lifestyle adjustment, and emotional adjustment during the divorce process. To cope with these challenges, the majority, if not all, of the women cited a support network, a sense of responsibility, a positive perspective, spirituality, and independence as effective coping resources. It was the hope of the participants and the researcher that this study would help other women experiencing divorce by illustrating how effective coping efforts can lead to greater happiness after divorce.
Subcortical Hyperintensities in Alzheimer's Disease and the Elderly: An MRI-based Study Examining Signs of Cerebrovascular Disease and Dementia
Keywords: Alzheimer's disease
Cerebrovascular disease
aging
MRI

Subcortical hyperintensities (SH) are believed to be observable signs of cerebrovascular disease, indicating some form of subcortical vasculopathy. Also commonly referred to as leukoariosis, these hyperintense signals on proton density, T2-weighted and fluid attenuated inversion recovery magnetic resonance images, are commonly observed phenomena in Alzheimer’s disease patients and elderly persons. Several SH sub-types with differential brain-behavior associations have been proposed in the scientific literature: periventricular, deep white, cystic fluid filled lacunar-like infarcts and perivascular Virchow-Robin spaces. This study will present Lesion Explorer (LE): a comprehensive tri-feature MRI-based processing pipeline that effectively and reliably quantifies SH sub-types in the context of additional brain tissues volumetrics in a regionalized manner. The LE pipeline was validated using a scan-rescan procedure. Finally, the LE pipeline was applied in a cross-sectional study of Alzheimer’s disease patients and normal elderly controls. Brain-behavior relationships were demonstrated with regional SH volumes and executive functioning, speed of mental processing, and verbal memory.
Psychological and Social Factors related to Physical Activities and Everyday Activities among South Asian High School Girls in the Toronto Area
Keywords: physical activity
adolescents
psychosocial factors
diary method
cultural factors

Background: South Asian girls have reported low levels of physical activity (PA) compared to other Canadian adolescents. Potential explanations include omissions in existing PA measures that don’t capture all types of PA, and factors discouraging PA in this group. Purpose: This study examined the quality and quantity of PA; compared PA participation using two self-report methods; and, examined psychosocial and cultural factors associated with PA in adolescent South Asian girls. Methods: 113 participants were recruited from community sources in Toronto. Data were collected using a structured electronic diary (3 weekdays; 2 weekend days) and a self-administered online questionnaire that included the Leisure Time Exercise questionnaire. Diaries were content analyzed and compared to PA reports in the questionnaire. Bivariate and multivariate regression analyses identified factors associated with PA. Results: Diaries revealed that when a range of PA types were captured, like walking activities and chores, PA levels were similar to representative data for Canadian youth. 92% of respondents reported at least 30 minutes of PA per day across their diary entries. However, 19% did not report any PA at the vigorous intensity level, and PA levels were lowest on weekends. Reports of PA in the diary and questionnaire were inconsistent, with considerably higher levels of PA reported in the questionnaire. Enrolment in physical education, enjoyment, control, fewer barriers, and social provisions were associated with greater PA. Conclusions: Physical activity levels were low, but results did not suggest that South Asian girls are more vulnerable to low levels of activity compared to other Canadian girls. Findings from the diary suggest that PA questionnaires would benefit from including a broader range of activity types with a variety of walking activities, and structured reflections to enhance data quality and minimize the potential for over-reporting. PA levels may be increased through mandatory physical education, curricula that emphasize how girls may engage in vigorous activities outside of classes, and changes to neighbourhood environments that would promote walking.
Synthetic and Theoretical Investigations of [3,3]-Sigmatropic Rearrangements and Development of Allylboration Reactions
Keywords: Organic chemistry
Sigmatropic rearrangement
Allylation
Claisen
Boron
Computational chemistry
Allylboration
Density functional theory
Domino reaction
Lanthanide

A summary of research conducted since September 2007 at the University of Toronto in the laboratory of Professor Robert A. Batey is presented in this thesis, which is divided into four chapters. The first chapter contains a two-part introduction, where aryl- and aliphatic-Claisen rearrangements are discussed in part 1, and the nucleophilic addition of organoboron reagents to unsaturated C–N functionalities is described in part 2. Chapter 2 contains research involving synthetic and theoretical studies of aryl-Claisen rearrangements and other sigmatropic reactions. The work towards developing the lanthanide-catalyzed domino aryl-Claisen rearrangement for the synthesis of contiguous aryl–C(sp³) moieties is presented first. This is followed by computational studies involving E/Z-selectivity differences for the aryl-Claisen rearrangement, which was an issue noted for the domino aryl-Claisen reaction of a linear substrate. The mechanistic origins of E/Z-selectivity differences for the mono aryl-Claisen rearrangement, which was experimentally ambiguous for over 40 years, is resolved through computational methods. A theoretical analysis of selectivity differences for the allylic azide rearrangement is also described. The third section contains a discussion of Eu(fod)3-catalyzed aryl-Claisen rearrangements on vinyl bromide systems and preliminary studies involving application of the substrates in cross-coupling reactions, and other attempted mono- and domino sigmatropic rearrangements are presented in the fourth section. In chapter 3, the search for computational methods that can accurately predict experimental free energy of activation barriers for the aliphatic-Claisen rearrangement through benchmarking studies with a priori kinetic barrier and kinetic isotope effect data is described. Methods were found to predict new valid transition states and predict ΔG‡ values with a mean unsigned error of 0.3 kcal/mol relative to experimental values. In chapter 4, the development of new allylboration reaction is outlined, involving the double allylboration of nitriles and anhydrides, and initial studies towards the first aminoallylboration reactions of N-aluminoaldimines to form 1,2-diamines.