VictorJuiz/thesis huggingface dataset:
Kinetic Consequences of Surface Oxygen Species during Catalytic C3H6-O2, CO-O2, and COx-H2 Reactions on Transition Metal and Alloy Clusters
Keywords: Catalysis
DFT
Kinetics
Methanation
Oxidation
Thermodynamics

C3H6 epoxidation, CO oxidation, and COx methanation reactions are important for emission abatement and value-added compound production. They occur on transition metal/alloy clusters via the kinetic coupling of steps that involve activation of carbon containing reactants (C3H6, COx) with co-reactants. The reaction mechanisms for each of these processes involve partial or total oxidations of reactants with distinct reactive oxidants. Kinetic and isotopic measurements, micro-kinetic modelling, and titration experiments reveal the mechanistic similarities between these seemingly different reaction systems, despite their distinctly different operating conditions and types of surface reactive oxygen species. For the first case of C3H6-O2 reactions, competitive epoxidation and combustion reactions occur on Ag clusters predominantly covered by O*. The desired epoxidation occurs via reactions between O* and C3H6. Contrarily, the undesired combustion to COx and H2O involves C-H bond cleavage by OOH*, which forms auto-catalytically from O2 and H2O. For the second case of CO oxidation, which is a step within C3H6 combustion, reactions between O2* and CO* take place on Ag and Group VIII metal cluster surfaces saturated with reactive O* or CO*. Here, the reactant ratios, reaction temperature, and the O* and CO* heats of adsorption on surfaces determine the O* and CO* coverages. While O* is much more abundant, O2* is the more reactive oxidant for CO oxidation. For the third case of COx methanation, a hydrogenation, the reaction occurs via the transfer of hydrogen from OH* to CH3* on Co and Ni-Co clusters partially covered with O* and via transfer of hydrogen from H* to CH3* on Ni and Ni-Co clusters partially covered with C*. The reaction conditions and metal affinities to O* and C* determine the competing adsorbate coverages. The competing coverages of reactive species lead to complex rate expressions that depend on the reaction temperature and inlet gas compositions. Simultaneously, the catalyst metal identity and average cluster diameters alter the heats of adsorption of the surface species and vary their reactivities and coverages. This study connects these kinetic and thermodynamic consequences across three catalytic processes and derives the expressions for these trends, allowing for reactor designs that optimize desired product yields.
Output Reach Control Problem with Applications to Motion Planning for Robotic Systems
Keywords: Integrator Systems
Motion Planning
Motion Primitives
Output Reach Control
Reach Control Problem

As electronic devices become more embedded into everyday products, an increasing number of consumer devices are being equipped with control systems. These control systems are sometimes required to achieve complex specifications such as safety constraints or switching between distinct tasks. Among a wide range of techniques to deal with the control design of complex systems, one is to partition the state space into polytopic regions, and solve a control problem on each region such that the collective behaviour of the hybrid system solves the original complex control specification. In this dissertation we consider such a methodology where the control problem on each polytopic region is called the {\em Reach Control Problem} (RCP). The RCP is to find a state feedback to make the closed-loop trajectories of an affine control system defined on a polytope reach and exit a prescribed facet of the polytope in finite time. There is already an extensive literature on the RCP. This dissertation extends this literature by considering the {\em Output Reach Control Problem} (ORCP). The ORCP is to control the output trajectory of the control system on a simplex in the output space, in contrast to control the entire state trajectory. We also extend the applications of the RCP by developing a unified framework for control with complex specifications. This dissertation contains four distinct contributions. The first contribution provides an extension of classical linear regulator theory to affine systems and exosystems. This extension then provides the basis to develop a framework for the output reach control problem with disturbances. The second contribution leverages existing literature on viability theory to convert the ORCP in the output space on a simplex to a RCP in the full state space on a polytope. The third contribution is to propose a unified framework for solving control problems with complex specifications. Our framework is targeted at robotic systems. Finally, our fourth contribution is a set of so called {\em motion primitives} which comprise one of the layers of our aforementioned framework. These motion primitives are based on our approach to the ORCP.
Effect of Nozzle-nozzle Interaction on Lean Flame Transitions in a Multi-swirler Combustor
Keywords: Blowoff
Cross-Nozzle Flame Transport
Laser Diagnostics
Multi-Nozzle Combustor
Nozzle-Nozzle Interaction

This work investigates the transition between different flame stabilization modes in a gas turbine model combustor consisting of a linear array of five interacting nozzles, which is representative of advanced designs for next generation engines. Simultaneous multi-kHz repetition rate OH planar laser induced fluorescence and stereoscopic particle image velocimetry were used to examine the hydrodynamics and nozzle-nozzle interactions during the transient flame blowoff and reattachment processes. Two different reactants feeding configurations were designed to isolate the effects of different operating and geometric parameters on the combustor's fuel lean performance. In the first configuration, reactants to each nozzle were fed through a common plenum; while reactants to each nozzle were controlled separately in the second configuration. The lean blowoff point was tested for different inter-nozzle spacings, by changing the nozzles receiving reactants. The combustor's lean operability was optimized when only two nozzles were operated, as a result of the complex interaction between the cross-nozzle flame transport, fluid dynamic strain field, and the recirculation strength. Nevertheless, blowoff occurred at a relatively constant Damkӧhler number. The blowoff/reattachment process for an individual flame was initiated in a similar manner to isolated bluff-body stabilized flames, though with cross-nozzle flame interactions providing additional means of re-stabilizing a partially extinguished flame. In the connected plenum configuration, blowoff/reattachment dynamics of the three central nozzles were coupled to each other. Blowoff transitions were preferentially initiated in one of the off-center nozzles, with the transition of subsequent nozzles occurring in a random order. Similarly, the center nozzle tended to be the last nozzle to reattach. However, such temporal coincidence of the blowoff/reattachment transitions were not observed in the individual plenum configuration, suggesting the upstream coupling is significant in the combustor dynamics. A statistical analysis demonstrated that changes in downstream conditions would lead to flow re-distribution inside the connected plenum. Both in-chamber and upstream cross-nozzle interactions are equally important in flame blowoff transitions inside a practical combustor, while the in-chamber cross-nozzle interaction plays a more important role in reattachment transitions.
The Space in Between: Healthy Public Policy Development in Canada’s Provincial North
Keywords: Context
Food environments
Healthy public policy
Population health interventions
Provincial North
Rural health

Healthy public policy is a cornerstone of public health practice, and a key strategy for creating enabling environments for health. A recent priority has been to better account for and integrate context into healthy public policy-making, including in the design, execution and evaluation of population health interventions. Healthy Public Policy may be an important tool for promoting health in the smaller cities and rural regions that comprise Canada’s Provincial North. Populations living in these regions share common health challenges and bear a disproportionate burden of poorer health outcomes compared to their urban counterparts. The objective of this research was to explore healthy public policy development for smaller cities and rural regions. An empirical focus on retail food environments in Canada’s Provincial North captured the contextual scale needed for this research aim. Through a community-university partnership in Northern British Columbia, I asked: (1) How is context accounted for and integrated in population health intervention planning? (2) What features of local context are most important to measure to build an evidence-base for action? I employed an interpretivist methodology and a mixed-methods approach, adopting a exploratory sequential design. Over the course of two years embedded in the field, I engaged in participant observation, and conducted workshops and key informant interviews to design a locally-relevant retail food environment assessment plan, then conducted environmental observation of stores to quantify features. Finally, I completed in-depth interviews with retail store operators to further examine qualitatively their experiences of contextual factors. I found that institutions, settings and communities are organized according to the regional connectedness of smaller cities and adjacent rural regions, which has implications for healthy public policy-making in Canada’s Provincial North. Regional connections engender contextual features that are important to measure and understand, but capacity challenges in public health as well as retail practice limit data collection and evidence use at this scale. Existing strategies such as partnerships and community-engagement planning utilized by public health practitioners should be preserved. Additionally, new partnerships with retailers are needed to identify contextual priorities for future action.
The Role of PAK Signaling in Synaptic Transmission and Plasticity and Social Memory in Mice
Keywords: Memory retrieval
Optogenetics
p21-activated kinases
Social recognition memory
Synaptic plasticity
Synaptic transmission

Social interactions are essential to our mental health and their deficits are hallmark characteristics in numerous brain disorders. Various subregions within the medial temporal lobe have been implicated in social memory, however, the underlying molecular and cellular mechanisms that tune these particular neural circuits in memory processing remain unclear. PAKs (p21-activated kinases) are a family of serine/threonine protein kinases that are target enzymes of the Rho family small GTPases and central regulators of both the actin cytoskeleton and neuronal morphology. PAK 1 and 3 are involved in the regulation of the structural and functional properties of the synapse, including dendritic spine morphology, synaptic transmission and plasticity, and learning and memory. Recent human and animal studies have revealed that perturbations in PAKs are implicated in several neurological and mental disorders including autism spectrum disorders (ASD) and intellectual disability (ID). These disorders are often characterized by social impairments, yet the cellular correlates within the neural circuits that subserve PAK function in social behaviour remains unknown. In this thesis, I explore five objectives which elucidates the role of PAK signaling in the entorhinal cortical perforant projections to the dentate gyrus (EC-DG) in social memory retrieval. First, I characterize the biochemical and cellular properties of a novel transgenic mouse model where the expression of a dominant negative mutation of PAK3 can be temporally and spatially controlled. Second, I demonstrate that the reversible disruption of PAK signaling impairs social recognition memory without affecting other behavioural responses. Third, using electrophysiological recording and imaging techniques, I show that presynaptic neurotransmitter release is specifically impaired at the EC-DG synapse in the mutant mice. Fourth, I use biochemical analyses and show that cofilin and the actin cytoskeleton are significantly altered in the mutant mice. Lastly, I demonstrate that acute optogenetic manipulation of the EC-DG terminals is sufficient to rescue the social memory deficits in the PAK3 transgenic mouse model. Together, these results identify a novel signaling pathway mediated by PAKs within the EC-DG circuit that governs social memory retrieval. Furthermore, these findings suggest potential circuit and molecular mechanisms important for the treatment of social disorders.
Dietary Factors Associated with Abdominal Adiposity in Postmenopausal Women
Keywords: abdominal adiposity
adiposity
carbohydrate intake
diet
dietary patterns
glycemic index

Elucidating modifiable dietary factors for adiposity, particularly abdominal adiposity, has important public health implications for the prevention of obesity and subsequent health risks. The emerging epidemiological evidence suggests that the nature of carbohydrate intake may be an etiological factor in adiposity. The objectives of the thesis were to examine the associations between various carbohydrate-related dietary factors (carbohydrate intake, dietary fibre intake, dietary patterns, dietary glycemic index, GI, and dietary glycemic load, GL) and measures of abdominal and total adiposity. These relationships were investigated in a cross-sectional study of Canadian postmenopausal women aged 50–69 years. Dual-energy X-ray absorptiometry (DXA) measures of abdominal adiposity and total adiposity were utilized, in addition to standard anthropometric measures. We found that total dietary fibre intake, but not total carbohydrate intake, was inversely associated with trunk fat mass (β = −0.127 kg; 95% confidence interval, CI: −0.210, −0.044). However, associations with trunk fat mass varied by food source, where there were positive associations between potato sources of carbohydrate (β = 0.096 kg; 95% CI: 0.019, 0.173) and fibre intake (β = 1.110 kg; 95% CI: 0.157, 2.064) and trunk fat mass. Additionally, a Western dietary pattern (high intake of meats, potatoes, and sweetened products) was positively associated with all measures of abdominal and total adiposity, while a Prudent dietary pattern (high intake of vegetables, fruit, legumes, grains, and cereals) was inversely associated with all measures of adiposity. Specifically, postmenopausal women with the greatest adherence to a Western dietary pattern had 4.52 kg (95% CI: 2.58, 6.45) greater trunk fat mass versus those with the lowest adherence, while postmenopausal women with the greatest adherence to a Prudent dietary pattern had −2.68 kg (95% CI: −4.45, −0.09) trunk fat mass compared to those with the lowest adherence. However, there was no evidence of linear associations between dietary GI or dietary GL and measures of abdominal and overall adiposity. Our findings of the contrasting associations with abdominal adiposity by carbohydrate and dietary fibre food sources and dietary patterns characterized by distinct carbohydrate food groups, suggest a potential role of carbohydrate quality in the accumulation of adipose tissue.
Chant Through the Change: Exploring the Pedagogical and Programmatic Benefits of Gregorian Chant in the Development of Male Adolescent Voices
Keywords: adolescent
chant
male
pedagogy
repertoire

The issue of lack of repertoire for males in the process of adolescent voice change has long been explored, but there still exists a significant lack of historical repertoire for these voice types. Recent research on the pedagogical benefits of singing Gregorian chant shows an overlap with key areas of concern for teachers of changing-voice males. This dissertation explores the efficacy of chant as a pedagogical and programmatic tool for working with adolescent male voices in the process of vocal mutation by establishing a repertoire of suitable chants and providing representative chants analyzed for their pedagogical benefits. The research for this study included analysis of 557 chants referenced in anthologies and pedagogical chant resources. I analyzed chants for historical significance, range, and floridity. Using criteria established by John Cooksey’s Contemporary Eclectic Theory (CET) for male adolescent voice change, I selected 77 suitable chants as appropriate repertoire for these voice types, arranged eight of these chants especially for changing voices using the principles of CET, and developed annotations with pedagogical implications.
Orthodox Jewish Mothers’ Lived Experiences of Perinatal Loss: An Interpretive Phenomenological Study
Keywords: bereavement
interpretive phenomenology
Orthodox Judaism
perinatal loss
qualitative
religion

The current study explored the lived experiences of Orthodox Jewish mothers whose baby was stillborn or died shortly after birth, within the context of their religion, families, and community. Within the framework of a qualitative, interpretive phenomenological research design, semi-structured interviews with seven Orthodox Jewish women were carried out to obtain a rich, detailed description of their perinatal loss experiences. As well, interviews were conducted with three Orthodox Jewish rabbis to provide further background for the information obtained from mothers. Thematic analysis of data collected from interviews with mothers yielded eight major themes: 1) Context Shapes the Evolving Story, 2) Engulfed with Awareness of Loss, 3) Mourning within a Framework of Halacha (Jewish law), 4) Relinquishing the Illusion of Control, 5) Conceptualizing the Baby as Holy Brings Meaning, 6) Acknowledgement Brings Comfort, 7) Diverse Challenges Intensify Grieving, and 8) Religious, Spiritual, and Personal Transformation. These themes and their relationship to relevant literature and to each other are discussed, followed by a consideration of research strengths, limitations, and practice implications. In addition to advancing the present understanding of cultural influences on perinatal loss in a theoretical sense, a planned outcome was that the findings obtained would contribute to the development of culturally sensitive perinatal bereavement care.
Tour-based Mode Choice Model in Activity-based Modelling Framework
Keywords: Activity-based modelling
Discrete-continuous choice
Dynamic discrete choice
Future expectation
Tour-based mode choice
Travel demand forecasting

This thesis presents a tour-based mode choice modelling structure for activity-based travel demand models by exploiting the classical dynamic discrete choice modelling approach. Many activity-based modelling systems rely on either trip-based or ‘simplified’ tour-based mode choice models that in many cases completely overlook the dynamics of mode choice behaviour. To contribute to filling this gap, this thesis applies a systematic approach of investigation to better understand the nature of tour-based mode choices and to propose a parsimonious modelling structure for it. The first investigation looks into the trip-based mode choice behaviour of post-secondary students commuting to universities in the City of Toronto. The second investigation uses a heteroskedastic dynamic discrete choice model for tour-based mode choices modelling with an empirical investigation of university students’ daily mode choices in Toronto. The third investigation uses a computationally tractable dynamic discrete choice modelling framework for modelling tour-based mode choices. The fourth investigation uses a random utility maximization -based dynamic discrete-continuous modelling approach to capture individuals’ tour-based modes and continuous time-expenditure choice trade-offs in a 24-hour time frame. The model results reveal that individuals’ sensitivity to travel costs varies, while their sensitivity to travel time remains stable. The empirical model reveals that users of newly introduced mobility services (e.g., Uber, Lyft) tend to have different mode choice patterns and value of travel time savings than non-users of these services. The forward-looking component reveals that availability of the modes for subsequent trips in the tour represent a significant portion of the utility of the current mode choices. In terms of the time-expenditure choice model, it is found that full-time employees and younger individuals tend to leave home earlier than part-time employees and older individuals. It is found that individuals are likely to spend long hours at work or school if they leave home early. Furthermore, individuals are likely to schedule non-mandatory activities, such as shopping, later in the day. The validation and policy evaluation results are promising. While the models proposed here can be easily developed in different regions across North America, opportunities also exist for the application of this type of analysis globally.
Disabling Relationships: Exploring Encounters in Segregated Special Needs Classrooms
Keywords: decolonial studies
disability studies
elementary teaching and learning
normalcy
postcolonial studies
post-structural feminisms

This work addresses how encounters between teachers, students and the researcher within segregated special needs classrooms both perpetuate and resist the normalizing narrative of schooling. In this study, I aim to demonstrate how subjectivities, onto-epistemologies and varying embodiments impress upon one another in ways that both shape and refuse to shape our relationships. My participatory classroom exploration took place during 15 weekly visits (Fall 2017) in a Primary Learning Disability (LD) class and a Primary Mild Intellectual Delay (MID) class at “Up North Public School.” Guided by disability studies, post-structural feminisms decolonial studies as well as postcolonial studies, I make a case for a methodology I refer to in this study as reading and being read in disabling ways. The intent here is to explore inhabiting our interpretive relationships with each other differently amidst disability through telling stories embedded in everyday classroom moments between teachers and students. In Part I of this study, I outline the theoretical and methodological orientations that allowed for my reflexive relations to my participant observations within two segregated special education classrooms. Part II addresses the ‘who’ (subjectivities), Part III addresses the ‘what’ (knowledges both vocal and silent), and Part IV addresses the ‘where’ (embodied and contextualized relations). By contending that disability impresses in ways that continue to challenge and transform, my study contributes to a much-needed critical engagement regarding what it means to teach and learn as we reimagine our conception of becoming human amidst disability.