VictorJuiz/thesis huggingface dataset:
Improvements in Hazard & Life Cycle Impact Assesment Method for Metals in Freshwaters - Addressing Issues of Metal, Speciation, Fate, Exposure and Ecotoxicity

Methods of chemical hazard ranking and toxic impact assessment estimate fate and toxicity assuming the chemical exists in dissolved and particulate phases and, for metals, that all dissolved species are equally bioavailable. This treatment of metals, similar to organic chemicals, introduced a significant error in their estimates of hazard ranking since metal bioavailability and ecotoxicity are related to truly dissolved phase and specifically free metal ion within it. My thesis addressed this concern by developing a new method that introduced Bioavailability Factor (BF) to the calculation of Comparative Toxicity Potentials (CTPs) for hazard ranking of chemicals; also known as Characterization Factors for use in Life Cycle Impact Assessment (LCIA). First, the metal speciation/complexation was incorporated into fate calculations by loosely coupling commercial geochemical metal speciation model, WHAM, with a multimedia fate model, USEtoxTM, which is originally designed to calculate CTPs for organic chemicals. Second, Biotic Ligand Model (BLM) was used to calculate the bioavailability-corrected adverse toxic effects of metals. This new method was applied to assess the implications of choosing environmental characteristics, notably freshwater chemistry, by calculating BFs and CTPs of several cationic metals (e.g., Cd, Cu, Co, Pb, Ni and Zn) using 12 European, 24 Canadian ecoregions, several distinct freshwater-types selected from large river and lake systems world-wide. The newly estimated metal CTPs (i.e., ecotoxicity potentials) are up to ~1000 times lower than previous values used in LCIA. Notably the model results showed that the absolute values of CTPs, and their relative ranking amongst chemicals, are a product of the characteristics of a receiving environment. Hence it is crucial to select a generic freshwater archetype on which this analysis should be based. Finally, the new model framework was extended to apply within the Unit World Model (UWM) framework to estimate critical loads (CLs) of cationic metals to surface aquatic systems.

Keywords: Life Cycle Impact Assessment
Metals
Ecotoxicity
Modelling
Advisor: Diamond, Miriam L.
In situ Proximity Ligation-­based Analysis Reveals Aberrant Dimerization and Activation of Epidermal Growth Factor Receptors Prevalent in Glioblastoma Multiforme

Aberrations in Epidermal Growth Factor Receptor (EGFR/ErbB1) signalling are the most common oncogenic stimuli in human glioblastoma multiforme (GBM). Interactions between mutant and wildtype ErbB family members in GBMs are of biological and potential therapeutic importance. In this thesis, we describe our work developing and optimizing a novel in situ proximity ligation assay (PLA) for dimerization and activation analysis of EGFR mutants prevalent in GBMs. Utilizing this novel in situ platform for EGFR dimerization analysis, we seek to systematically interrogate the dimerization capacity and activation status amongst EGFR and EGFR mutants. Our in vitro analysis using this platform demonstrates the aberrant homo-/hetero-dimeric properties of EGFRvIII and EGFRc958 mutants, the two most common mutants associated with EGFR amplification in GBMs. In addition, dimer phospho-activation status can be detected using in situ PLA with ≥ 16-fold sensitivity and ≥ 17-fold signal-to-noise than phospho-EGFR measurements currently undertaken with IHC or IF. These aberrant features are not overexpression dependent but appear independent of cellular expression levels, suggesting inherent properties of the mutant receptors. This EGFR dimerization/activation detection platform may also be useful for evaluating novel anti-EGFR therapeutics. Our data suggests that various EGFR monoclonal antibody therapies have unique dimerization blocking abilities and that certain mutant EGFR dimer configurations can evade blockage by anti-EGFR treatments. Furthermore, we report for the first time the detection of wt- and EGFRvIII dimerization in GBM specimens, in keeping with our prior cell line data, and a potential feature of prognostic or diagnostic value in GBMs harbouring them. Additionally, we demonstrate the utility of this platform for measuring pEGFR and total EGFR expression on tissue samples, which has not been efficacious to date with conventional antibody-mediated techniques. Results from this thesis may therefore provide novel insights into the interaction and activation characteristics of EGFR mutants prevalent in GBMs, as well as the efficacy of current anti-EGFR therapies to target these mutants. In summary, these findings demonstrate the successful application of a novel in situ EGFR molecular detection platform which may have clinical utility in diagnostic evaluation or stratification of GBM patient subgroups for prognosis and treatment. Furthermore, since PLA allows specimen assessment of not only expression and activation, but also dimerization, which is not evaluated by current IHC techniques, it will likely serve as a way to evaluate promising anti-EGFR strategies directed at preventing EGFR dimerization and activation.

Keywords: EGFR
Glioblastoma multiforme
dimerization
activation
Advisor: Guha, Abhijit
Schools, Child Welfare and Well-being: Dimensions of Collective Responsibility for Maltreated Children Living at Home

This qualitative study examines collective responsibility for the well-being of maltreated children who remain at home. Based on accounts of mothers, teachers and child welfare workers, and policy officials, the study uses institutional ethnography to examine how schools and child welfare authorities work together and with families. Contributing to the socio-legal literature, it explores understandings of responsibility in formal law and in practice. The policy response to these children’s needs raises significant theoretical and political issues because they are on the borderlands of public and private responsibility. Child welfare involvement signals public intervention is required to ensure protection and well-being. Strong, proactive, and coordinated support by public authorities should follow. However, data suggest three pervasive theoretical or political accounts legitimize very limited support. (1) The notion of home and school as separate spheres. Participants understand and in theory support the highly prescriptive regulation governing reporting and contact between schools and CAS. But in practice participants pointed to limits on responsibility for knowledge or communication across the boundaries. Participants acknowledged limited knowledge or communication despite a regulatory regime that promotes and assumes it. (2) Comprehensive family responsibility. Deeply-rooted notions of family responsibility and autonomy render public support for struggling families and children relatively discretionary. A policy and practice scan shows child welfare provides less educational support to children living in the community relative to those in foster care, and minimal individual or systemic accountability for services to these children. (3) Persistent heroic narratives of the teacher who ‘makes a difference’ through exceptional commitment to struggling students. To relegate caring work to realm of personal commitment privatizes responsibility for an important aspect of effective teaching. Though cited as exemplary, the exercise of these responsibilities is not supported, not demanded, and not planned for, which is problematic for interagency co-operation and teacher burnout. These political and institutional narratives limit the system’s response to the needs of these vulnerable children to discretion and chance. Meeting their needs requires not only a focus on coordination across bureaucratic boundaries, but also strengthening the visibility of, and accountability for, issues of well-being within education and child welfare.

Keywords: schools
child welfare
maltreatment
responsibility
mothers
teachers
family service workers
Advisor: Gaskell, Jane
Extensions to the Visual Odometry Pipeline for the Exploration of Planetary Surfaces

Mars represents one of the most important targets for space exploration in the next 10 to 30 years, particularly because of evidence of liquid water in the planet's past. Current environmental conditions dictate that any existing water reserves will be in the form of ice; finding and sampling these ice deposits would further the study of the planet's climate history, further the search for evidence of life, and facilitate in-situ resource utilization during future manned exploration missions. This thesis presents a suite of algorithms to help enable a robotic ice-prospecting mission to Mars. Starting from visual odometry---the estimation of a rover's motion using a stereo camera as the primary sensor---we develop the following extensions: (i) a coupled surface/subsurface modelling system that provides novel data products to scientists working remotely, (ii) an autonomous retrotraverse system that allows a rover to return to previously visited places along a route for sampling, or to return a sample to an ascent vehicle, and (iii) the extension of the appearance-based visual odometry pipeline to an actively illuminated light detection and ranging sensor that provides data similar to a stereo camera but is not reliant on consistent ambient lighting, thereby enabling appearance-based vision techniques to be used in environments that are not conducive to passive cameras, such as underground mines or permanently shadowed craters on the moon. All algorithms are evaluated on real data collected using our field robot at the University of Toronto Institute for Aerospace Studies, or at a planetary analogue site on Devon Island, in the Canadian High Arctic.

Advisor: Barfoot, Timothy D.
"De par chez nous:" Fiddling Traditions and Acadian Identity on Prince Edward Island

On a small island in the Gulf of Saint Lawrence a distinct Francophone community has persisted for nearly three hundred years despite historical traumas and the pressures exerted by a majority Anglophone environment. The factors that have contributed to the persistence of this community are a matter of some debate, yet the cultural identity of the Acadians of Prince Edward Island in the twenty-first century appears to have remained intact. Contrary to a popular discourse of identity "revival," this distinct culture is neither a recent phenomenon nor is it something that is homogeneously pan-Acadian. While much popular and scholarly discourse on the Acadians centres on their tragic past and nationalist perspectives of Acadian identity construction, this dissertation focuses on how identity is created, perceived and expressed in a local context. Music plays a key role in articulating this local identity; it helps to create and maintain social relationships both within the community and with other cultural groups. The emergence of a distinct musical tradition has contributed substantially to the production and maintenance of cultural identity amongst these Island Acadians. Through case studies of specific performance contexts, individual musicians and professional groups, I examine current and ongoing processes of Acadian cultural definition and how musicians negotiate the dichotomy of traditional and modern performance contexts and forms of expression. I consider the musical alliances and exchanges that inform the experiences of these Islanders and how these intercultural encounters have influenced local musical practices and discourses about Acadian identity. My research demonstrates that contemporary cultural markers, and particularly music, are primary tools through which members of this invisible minority cultural group define and present their ethno-cultural identity both locally and to cultural outsiders.

Keywords: Acadian
Fiddling
Prince Edward Island
Ethnomusicology
Identity
Traditional music in Canada
Cultural Revival
Community
Advisor: Averill, Gage
Elliott, Robin
Extensions of Input-output Stability Theory and the Control of Aerospace Systems

This thesis is concerned with input-output stability theory. Within this framework, it is of interest how inputs map to outputs through an operator that represents a system to be controlled or the controller itself. The Small Gain, Passivity, and Conic Sector Stability Theorems can be used to assess the stability of a negative feedback interconnection involving two systems that each have specific input-output properties. Our first contribution concerns characterization of the input-output properties of linear time-varying (LTV) systems. We present various theorems that ensure that a LTV system has finite gain, is passive, or is conic. We also consider the stability of various negative feedback interconnections. Motivated by the robust nature of passivity-based control, we consider how to overcome passivity violations. This investigation leads to the hybrid conic systems framework whereby systems are described in terms of multiple conic bounds over different operating ranges. A special case relevant to systems that experience a passivity violation is the hybrid passive/finite gain framework. Sufficient conditions are derived that ensure the negative feedback interconnection of two hybrid conic systems is stable. The input-output properties of gain-scheduled systems are also investigated. We show that a gain-scheduled system composed of conic subsystems has conic bounds as well. Using the conic bounds of the subsystems along with the scheduling signal properties, the overall conic bounds of the gain-scheduled system can be calculated. We also show that when hybrid very strictly passive/finite gain (VSP/finite gain) subsystems are gain-scheduled, the overall map is also hybrid VSP/finite gain. Being concerned with the control of aerospace systems, we use the theory developed in this thesis to control two interesting plants. We consider passivity-based control of a spacecraft endowed with magnetic torque rods and reaction wheels. In particular, we synthesize a LTV input strictly passive controller. Using hybrid theory we control single- and two-link flexible manipulators. We present two controller synthesis schemes, each of which employs numerical optimization techniques and attempts to have the hybrid VSP/finite gain controllers mimic a H2 controller. One of our synthesis methods uses the Generalized Kalman-Yakubovich-Popov Lemma, thus realizing a convex optimization problem.

Keywords: control theory
input-output stability
passivity-based control
control of flexible robotic manipulators
spacecraft attitude control
Advisor: Damaren, Christopher John
The Effects of Antecendent Exercise on Students’ Disruptive Behaviours: An Exploratory Analysis of Temporal Effects and Mechanism of Action

Low autonomic arousal, as measured through resting heart rate, has been shown to be one of the best-replicated biological correlates of antisocial and aggressive behaviour. According to the stimulation seeking theory, low arousal represents an unpleasant physiological state. In line with this theory, antisocial individuals purposely engage in antisocial and aggressive acts in an attempt to increase stimulation and achieve more agreeable arousal levels. If, as the stimulation seeking theory suggests, the function of antisocial behaviour is to increase physiological arousal levels, exposing antisocial individuals to functionally equivalent forms of arousing situations (e.g., aerobic exercise) should result in a reduction in aberrant conduct. Although a growing body of literature indicates that antecedent exercise is effective at reducing antisocial and aggressive behaviours, the present investigation sets out to explore two fundamental questions about this approach that remain unclear. First, there is a paucity of research examining the temporal effects of antecedent exercise. Secondly, little is known about the mechanism of action accounting for behavioural improvements following exercise. The present investigation involved 4 students (age range 11-14) enrolled in a closed behavioural classroom due to severe aggressive, disruptive, and oppositional behaviours. Through the use of an alternating treatment design with baseline, students were first exposed to baseline conditions and then to two experimental conditions, (i.e., an antecedent exercise condition and a control condition) in a randomized fashion. Results indicated that 30 minutes of moderate to intense aerobic exercise resulted in approximately 90 minutes of behavioural improvements. In addition, results suggest an inverse relationship between arousal levels and behavioural difficulties. The potential utility of antecedent exercise as a treatment alternative in schools for students with severe antisocial behaviours is discussed.

Keywords: Antecedent exercise
disruptive behaviours
Childhood aggression
Advisor: Ducharme, Joseph
Learning to Teach Health and Physical Education: The Experiences of Elementary Student Teachers

This research investigates elementary student teachers’ experiences of learning to teach health and physical education (HPE) in a one-year pre-service teacher education program at Windermere University in Canada. The participants in the research are preparing to become elementary classroom teachers; a group who often recall negative prior experiences of HPE from their time as school pupils and report an overwhelming lack of preparation and confidence to teach HPE. Mixed-methods of data gathering were employed in the form of pre- and post-test surveys of 308 student teachers, and three interviews conducted with a purposive sample of ten student teachers. Four main findings emerged from the research. First, elementary student teachers’ embodied identity as healthy and physically active individuals profoundly shaped their prior experiences of HPE. Second, the 12-hour HPE course offered in Windermere’s pre-service program broadened student teachers’ views of HPE and provided them with some basic strategies for teaching elementary HPE. Third, the practice teaching experience provided some student teachers with opportunities to either observe or to try teaching HPE; few had opportunities to do both. Fourth, there was a positive and statistically significant change in student teachers’ identities as teachers of HPE from the beginning to the end of the pre-service teacher education program. Implications for school HPE, pre-service teacher education programs, policy regarding teachers of HPE, and future avenues for research are discussed in light of the findings.

Keywords: Teacher Education
Physical Education
Advisor: Kosnik, Clare
Top-down Influences on Selective Attention across the Extended Visual Field

The research focuses on the role of top-down influences on selective attention across the attentional visual field. The attentional visual field is the subset of the visual field in which attentional processes take place. The size of the attentional visual field is relatively large compared to the areas considered by most empirical studies of visual attention to date. Three possible forms of top-down influence are examined: 1) the expectation of the size of the area in which the target is likely to occur; 2) the expectation of the direction in which the target is likely to occur; and 3) existing unconscious bias in the spatial distribution of attention. Results from Experiment 1 suggest that participants modify the size of the attended area according to their expectation of the location of the target. Experiment 2 demonstrates that focus of attention can be oriented toward the expected target direction. Experiment 3 reveals that, even when no conscious control is involved, the distribution of attention is biased toward certain areas. Theoretical considerations are discussed, including the introduction of a simple statistical model to assist in conceptualizing the modifications of the distribution of attention over the attentional visual field. Practical applications of the results are also discussed.

Keywords: selective attention
top-down influence
attentional visual field
Advisor: Spence, Ian
Where Outtreach Meets Outrage: Racial Equity Policy Formation at the Canada Council for the Arts (1989-1999)

Where Outreach Meets Outrage: Racial Equity at the Canada Council for the Arts (1989-1999), examines the early formation of racial equity policies at The Canada Council for the Arts. In this research project, I am primarily interested in understanding the ways in which ‘culture’ is employed by the state, the Canada Council for the Arts and by black artists to articulate and communicate complex issues that pertain to notions of art, citizenship, solidarity, justice, multiculturalism, belonging and nationhood. The research places culture and cultural production centrally within claims and calls by racialized artists for the ethical redistribution of societal resources and participation in societal structures. I look at questions of how community is produced and struggled over in relation to claims for cultural resources. This thesis employs an interdisciplinary approach drawn from the disciplines of sociology, anthropology and critical cultural studies to allow the complex relationships between activities of the Canadian state, racial equity policy making at the Canada Council, and grass roots social activism to emerge. I argue that state practices of management are elastic and that racial equity policies at the Canada Council emerged out of a confluence of transformational activities simultaneously taking place at the state/institutional and grassroots levels. The significance of this research project is that it fuses contemporary cultural production and art within contemporary social justice paradigms that seek to understand the processes and practices within liberalism that produce oppressions and resistance through an exclusionary politics of representation. This dissertation study will have both applied and theoretical implications in the Canadian context both within and outside of the academy in the fields of the arts, cultural policy and education.

Keywords: Racial policy formation in the arts - Canada
Cultural Policy - Canada
Black cultural activism - Canada
Advisor: Walcott, Rinaldo