title: High-Throughput Dense Wireless Networks in Unlicensed Spectrum

contributor:
Blostein, Steven D.
Electrical and Computer Engineering

subject:
Wireless Networks
High Density WLANs
CSMA/CA Protocol
Unlicensed Spectrum
Node Density
Spatial Reuse
IEEE 802.11 Networks
Channel Access Probability
Coverage Probability
PCS Threshold
CCA Threshold
5G New Radio

abstract:
Dense deployment of wireless local area networks (WLANs) will support the prolific data traffic in future wireless networks beyond fifth generation (B5G), either as small cells for cellular data offloading or last-miles for high throughput broadband connectivity. Interference and contention from large numbers of concurrent spectrum sharing nodes, spatial reuse and coexistence of multiple radio access technologies (RATs) are some of the challenges in high density WLANs. This thesis focuses on improving performance of dense WLAN in the presence of interference and contention among densely distributed stations (STAs) and access points (APs).

Interference inherently depends on the distribution of users among the available APs. To that effect, multiuser (MU) based AP association is proposed to associate groups of users to an AP to maximize sum-rate, as opposed to several single-user (SU) frameworks in existence. The MU-AP association problem is solved using a proposed graph-theoretic polynomial time algorithm and a proposed dual ascent method, which require channel knowledge to perform MU-AP association. To avert constant a priori channel information, an alternative framework is proposed to efficiently perform association based on spatial statistics of a network.

For spatial reuse, the physical carrier sensing (PCS) and the energy detection (ED) thresholds determine separation of multiple concurrent transmissions in space. PCS threshold is used by Wireless Fidelity (WiFi) WLAN nodes to detect WiFi-like signals from active transmissions while ED thresholds are used to detect non-WiFi preambles. Using stochastic geometry tools, frameworks are proposed for efficient selection of the PCS and ED thresholds that are network-specific and improve spatial average throughput. With efficient separation of concurrent transmissions, interference is further reduced.

To jointly address the user-AP association and PCS threshold selection problem, a rate-maximizing framework is proposed. A user-AP association solution is first obtained. PCS threshold selection is then optimized based on the achieved user-AP association. Densification, inevitable in future WLANs in improving performance in the presence of large numbers of contending nodes, is critical to delivering the required service level in next generation wireless networks. Analysis of the tradeoffs between densification and overall throughput is provided to determine node densities that achieve maximum rate.

abstract: PhD


title: Fair-weather liberalism: institutional preparedness for severe climate change

contributor:
Farrelly, Colin
Philosophy

rights: Attribution-NonCommercial 3.0 United States

rights: Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada

rights: ProQuest PhD and Master's Theses International Dissemination Agreement

rights: Intellectual Property Guidelines at Queen's University

rights: This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.

subject:
climate change
liberalism
political philosophy

abstract: What if we fail to mitigate and adapt to climate change, and so face its more severe impacts? I argue we must take this possibility seriously and doing so reveals a new obligation of climate justice – contingency planning for severe climate change. Contingency planning prepares us for undesirable possible futures. I argue for its philosophical grounding in an epistemology of futurity – possibilism – that imagines the future as a broad range of possibilities to be prepared for. I set out to draft a contingency plan that looks to safeguard liberal democracy against the impacts of severe climate change including scarcity, violence, and migration. I argue that many of liberalism’s most immediate theoretical resources are unhelpful in acknowledging the obligation of contingency planning, and in detailing the normative content of these plans. Much of liberalism is fair-weather. It either fails to properly identify the problems posed by severe climate change, misreads their normative contours, or fails to offer adequate solutions to them. But mapping these failures also helps us see the possibility of a new, climate-robust liberalism that can build institutional preparedness for severe climate change.

abstract: PhD


title: Attractiveness and Sexual Response

contributor:
Chivers, Meredith
Psychology

subject:
arousal
attractiveness
sexual response
menstrual cycle
ovulatory shift hypothesis
attention
physical attractiveness
visual attention
concurrent measurement

abstract:
Gynephilic (attracted to women) men’s sexual responses are strongly dependent upon the gender of a sexual target, while androphilic (attracted to men) women’s sexual responses may be more dependent upon contextual cues other than gender (like physical attractiveness). Research suggests that our nervous systems have been shaped through sexual selection to respond preferentially to cues of attractiveness (as they provide meaningful cues of health and reproductive viability of potential sexual partners). Research also suggests that women’s preference for cues of attractiveness may be highest during periods of the menstrual cycle when conception is most likely. The effect of attractiveness cues on men and women’s sexual arousal has never been tested directly.

This dissertation employs one large, within-subjects design, using concurrent measurement of self-reported arousal, genital arousal, self-reported attention, and visual attention patterns to examine three objectives: (1) men and women’s genital and self-reported arousal to cues of attractiveness and gender; (2) women’s sexual arousal to these cues across the menstrual cycle; and (3) men and women’s attention to cues of attractiveness and gender and its relationship with sexual response.

Gender and attractiveness proved to be important determinants in men and women’s self-reported and genital arousal, self-reported attention, and visual attention patterns. Though patterns of response varied somewhat between dependent measure and participants’ gender, generally, men and women were found to respond more to attractive than unattractive stimulus types and to their preferred, relative to their non-preferred, genders. Though clear menstrual cycle effects did not emerge among women’s responses to cues of attractiveness and gender, women’s self-reported arousal, genital arousal, and self-reported attention were found to vary by testing order (if they were tested first in the follicular or luteal phase of their menstrual cycles), such that women tested in their follicular phase first showed greater differentiation in their responding to attractive relative to unattractive sexual targets, than women tested in their luteal phase first. Finally, self-reported (but not visual) attention patterns were found to be meaningfully related to men and women’s self-reported and genital arousal to cues of gender (but not cues of attractiveness). Implications and future directions are discussed.

abstract: PhD


title: Identification of Novel Receptor Tyrosine Kinases Regulating the Hippo Pathway in Cancer Cells

contributor:
Yang, Xiaolong
Pathology and Molecular Medicine

subject:
Hippo Pathway
YAP
TAZ
Biosensor
Cancer

abstract: Several studies have shown that the Hippo pathway plays an important role in tissue growth, organ size control, and cell death.  Deregulation of the Hippo pathway contributes to loss of cell contact inhibition and continuing cell proliferation, which is observed during tumorigenesis. Although many studies have been done to clarify the role of the Hippo pathway in various biological functions, currently the connection between the Hippo pathway and its potential upstream kinase regulators is not very clear. Since the overexpression and deregulation of receptor protein kinases (RTKs) have a pivotal role in many cancers, we hypothesize that RTKs may be involved in tumorigenesis by inhibiting the Hippo pathway.  To test the hypothesis, we developed a biosensor based on split-luciferase complementation assay. To find new RTKs which regulate the Hippo pathway, gain of function and kinase-inhibitor screenings were performed. We found that the many of RTKs could regulate the Hippo signaling activity. We further characterized several of these novel relationships VEGFR, [TAM family members (TYRO3, AXL, METRK),RET, and FGFR family members (FGFR1 and FGFR2)] and found that the Hippo effectors YAP/TAZ are central mediators of the tumorigenic phenotypes (e.g., increased cell proliferation, transformation, increased cell motility, and angiogenesis) induced by these RTKs and their extracellular ligands (Gas6,GDNF, and FGF) through either PI3K or MAPK signaling pathway. Remarkably, we found three new tyrosine-phosphorylation sites on YAP, which regulate its function. Our studies indicate that some RTKs also regulate the Hippo pathway through interaction or phosphorylation of LATS, YAP, and TEAD. In conclusion, these findings highlight the pivotal role of the Hippo pathway in mediating RTK-MAPK/PI3K signalling and provide a compelling rationale for targeting YAP/TAZ in RTK-driven cancer therapies.

abstract: PhD


title: The Effects of Variable Levels of p75 Expression on Aberrant Sympathetic Axon Sprouting Into Sensory Ganglia of Mice Overexpressing Levels of NGF Production

contributor:
Kawaja, Michael
Neuroscience Studies

subject:
neuroscience
p75
Neurotrophin
sympathetic sprouting
nerve growth factor

abstract:
Growth and regeneration of nervous tissue in adult mammalian organisms is limited to a few
locations in the body, and to special circumstances that induce proliferation. One way that neuronal trophism can be initiated is by overexpressing the gene coding for Nerve Growth Factor (NGF) under active promoters, causing an aberrant growth of sympathetic axons into the sensory ganglia of an animal. This phenomenon has been shown in certain environments in the presence of p75 neurotrophin receptor and found to be missing in absence of the same receptor. However, previous research has not looked at situations where only one allele of the p75 Neurotrophin Receptor (p75NTR) is present. To fill this gap in the literature, a rodent model with elevated levels of NGF, and a single functioning allele of p75NTR was investigated and quantitatively assessed against its genetically alternate littermates to determine the impact on sympathosensory sprouting in animals having one mutated p75NTR allele. It was discovered that while the mutation of the p75NTR allele had minimal impact on the morphology of sympathosensory sprouting into the brains of these animals, it induced not only greater sympathetic sprouting into sensory ganglia than its wildtype and knockout counterparts, but also augmented the density of the peculiar perineuronal plexuses found forming around a subset of sensory neurons within the dorsal root ganglia and the trigeminal ganglia. This study suggests that satellite glial cells are a key component of sympathosensory sprouting, and that the gain-of-function mutation within these heterozygous animals could be used as a model for further research into sympathetically maintained pain.

abstract: M.Sc.


title: Writing the Other, Writing the Self: British Travelogues and Iranian Women’s Life Writing, 1890s-1920s

contributor:
Bongie, Chris
English Language and Literature

subject:
Life writing
Travelogue
Women
Qajar Iran

abstract:
This dissertation examines the ways that Iranian women’s writing deployed and reshaped the life narrative form to suit the social milieu of early twentieth-century Iran. In terms of scope, this project examines British women’s travelogues written between the 1890s and 1920s as well as writings by Iranian women from the same time period. This genealogical framework can, I argue, inform contemporary transnational feminist debates in light of the growing marketability of Middle Eastern women’s life narratives in the Western literary market.
Chapter 2 explores the dual work that representations of Iranian womanhood performed in British women’s travelogues in terms of both documenting the Oriental Other and relationally defining the self. As this chapter shall discuss, to the female British travelers writing between the 1890s and 1920s, the travelogue – which occupied an important place in England’s colonial project – provided ample opportunity for self-exploration. In this context, representations of the Iranian Other came to serve as a counterpoint against which the narrator’s image of an autonomous, liberated self could be textually enhanced.
Chapter 3 analyzes Astarābādī’s Ma’āyib-i Rijāl (1894) and the memoir of Tāj us-Saltanih (c. 1914), both of which were autobiographical and drew upon the author’s personal life experiences as grounds from which to broach broader social issues such as women’s rights and reform. This chapter illustrates how the textual and ideological ambivalences of Tāj’s memoir were rooted in the growing influence of Eurocentric prejudices that promulgated cultural misrepresentations of Iran as backward and corrupt.
Chapter 4 is divided into two parts. Part 1 explores the ways that the early women’s journals of the 1910s legitimized women’s rights to publication by adopting the eugenic elements of Iran’s nationalist discourses and emphasizing the role that women would play in the modernization of the nation. Part 2 examines how (both male and female) contributors to the late-1920s journal Peyk-i Sa’ādat-i Nisvān adopted the rhetorical potentials of the first-person narrative form to address collective issues of reform and national progress. As this chapter demonstrates, the strategic use of women’s narratives alerts us to the potential limits of the “genuine” use of the first-person voice.

abstract: PhD


title: Phase Space Structure of Disequilibrium in the Milky Way

contributor: Physics, Engineering Physics and Astronomy

subject:
Galaxy
Galactic Dynamics
Milky Way
Dynamics
Dynamic Mode Decomposition
Bending waves
Simulation
Phase space
Distribution function

abstract:
Following Gaia Data Release 2, observations of spiral structure in the vertical phase space of the Milky Way have been made. In this thesis we set out to explain these structures, using a combination of analytic modeling, simulations, and Dynamic Mode Decomposition to study explicitly their formation and evolution in the presence of self gravity. In doing so, we have demonstrated the first application of DMD to collisionless, self-gravitating systems.

We show by comparison of self-gravitating and independent-particle simulations in a realistic Milky Way model, that the timescale of phase space spiral formation is drastically dependent on whether or not stars mutually interact. This is followed by the proposition that mutually interacting stars in a background potential conducive to oscillations can produce a persisting spiral in their phase space distribution, existing on much longer time scales than predicted by traditional kinematic phase mixing arguments.

Our proposition is investigated with use of Dynamic Mode Decomposition, which facilitates determining eigenfunctions of the time evolution operator of a system from data snapshots. We apply this to two one-dimensional models for the vertical structure of the Milky Way: the homogeneous slab, and the isothermal plane. We found that the eigenfunctions, or modes, determined for a self-gravitating system undergoing phase mixing comprise a set of modes similar to what is expected from linear perturbation theory. Particularly, the disequilibrium distribution function can be modeled as the superposition of an equilibrium mode and a combination of perturbative modes, all computed directly from snapshots of the system.

DMD solutions are determined for the isothermal plane model with a variable relative dominance of self-gravity and background potential. We find that there is a regime of relative dominance where modes of the distribution function containing pronounced spiral structure can persist on extremely long time scales. This implies that a single snapshot of a phase space spiral could belong to an evolution where the distribution function remains in a spiral for long times, driven by mutual interactions, as opposed to the spiral being a short lived transient response as in kinematic phase mixing.

abstract: M.Sc.


title: Fascism and Settler Colonialism in Canada

contributor:
Guenther, Lisa
Philosophy

subject:
Fascism
Settler Colonialism
Canada
Deleuze and Guattari
Whiteness
Property
Territory
Settler Whitespace
Biopolitics
Nationalism
Microfascisms
Desiring Fascism
Replacement

abstract: This thesis aims to map out the relationship between fascism and settler colonialism in Canada. In the first chapter, I go through a number of theories of fascism, including by contemporary historians and 20th century Marxists. I draw on the work of Deleuze and Guattari and their distinction between molar and molecular (or micro) fascism. In the context in a country like Canada, in which fascism has not taken on a molar form on the state level, I argue that we need an account of fascism that is sensitive to its molecular expressions. I highlight three tendencies of fascism that we should keep an eye on if we are concerned about its emergence. In the second chapter, I explore the role of the settler state in cultivating and producing microfascist affects, feelings, and beliefs. I examine the deputization of settlers by the Canadian state in order to expand and protect territory and the way this cultivates racist affect and encourages (often fatal) acts of violence. Finally, I consider the way whiteness in Canada becomes a territorializing force, and sketch out a model of private property I call settler whitespace. In the third chapter, I consider the fascist rhetoric around “the great replacement” and “white genocide” in relation to the structure of settler colonialism. I consider the logic of replacement in Canada as not just a territorial project, but one that also creates a racially exclusionary idea of Canadian nationalism. Fascist rhetoric not only echoes the Canadian history of eugenics, it inverts the practices of replacement and genocide inherent to the settler state, and engages in what I will call a biopolitics of the nation.  This inversion is not just a coincidence, it is part of what makes this rhetoric so affectively compelling. I will conclude by arguing that given the intimate relationship between fascism and settler colonialism in Canada, anti-fascist action must follow the lead of practices of Indigenous resurgence.

abstract: M.A.


title: A Multimethod Investigation of Women's Sexual Arousal

contributor:
Pukall, Caroline
Psychology

subject:
Sexual arousal
Sexual psychophysiology
Genital response
Laser Doppler imaging
Laser Doppler flowmetry
Litmus test strip

abstract: The research program presented in this dissertation describes a multimethod investigation of women’s sexual arousal. Across three empirical studies, alternative approaches to sexual psychophysiology research were adopted to further develop the ways in which women’s sexual arousal is elicited and measured in the laboratory. In Chapter 2, two direct measures of genital response—the litmus test strip and the laser Doppler imager—were used concurrently to provide the first empirical evidence of the positive relationship between genital lubrication and blood flow during sexual arousal. Both measures detected a genital response and were suitable for repeated measurement within a single session; however, only the laser Doppler imager detected low levels of genital response. Chapter 3 validated the only direct and continuous measure of genital blood flow in women—laser Doppler flowmetry. The study showed that laser Doppler flowmetry is a valid and sensitive measure of genital response that is reliable across testing sessions, and results indicated that genital blood flow assessed by flowmetry is highly responsive over time. In consideration of the way in which sexual arousal is elicited in the laboratory, Chapter 4 applied a novel stimulus selection task, which enabled the direct comparison of using participant- versus researcher-selected sexual stimuli to elicit sexual arousal. The study demonstrated the feasibility and utility of using participant-selected sexual stimuli in sexual psychophysiology research, such that a participant-selected sexual stimulus elicited equal or greater sexual arousal than a researcher-selected one. The studies that comprise this dissertation represent alternative approaches to the dominant methods used in sexual psychophysiology research. The studies described herein have implications for experimental and applied sexual arousal research. The multiple methods used to elicit and measure sexual arousal in this program of research are novel and show promise for enhancing the study of women’s sexual arousal.

abstract: PhD


title: A Window to the Mind: Validation of a New Method to Measure Thought Dynamics Using Brain Network Meta-State Transitions

contributor:
Poppenk, Jordan
Neuroscience Studies

subject:
spontaneous thought
functional neuroimaging
dimensionality reduction
neurocinematics
time-varying functional connectivity
event segmentation

abstract:
In addition to what people are thinking about, researchers are also increasingly interested in how humans flow continuously from one mental state to the next (i.e., the flights and perches of thought; James, 1890). Can we pinpoint these moments of flight directly from neural signals? I drew upon the Human Connectome Project’s Young Adult functional magnetic resonance imaging (fMRI) dataset to characterize the psychological meaning of changes in functional connectivity during movie-viewing and at rest. I began with a representation of brain activity at each timepoint as the set of activations across 15 networks, and used new methods to embed this high-dimensional network representation onto a two-dimensional space of possible network configurations (network meta-states). Furthermore, I identified large jumps between consecutive timepoints in the reduced space, which I call meta-state transitions and should reflect prominent changes in the configuration of active networks.

I found that participants’ meta-state transitions were strongly related to the progression of meaning across events within movie stimuli. Meta-state transitions also shared many characteristics across movie and resting fMRI data, including concurrence with activation of brain regions associated with spontaneous thought, suppression by engagement of attention regions, and trait-like rates of occurrence. Based on these features, as well as the centrality of semantics to thought, I argue that meta-state transitions correspond to the initiation of new thoughts, and that characterizing transition features may serve as a direct neural measurement of how one thinks (i.e., their mentation). By exploring neural and behavioural correlates of meta-state transition rate and transition group alignment during movie-viewing, I also illustrate how this approach can contribute insights to emerging research on thought dynamics by bridging the gap between behavioural assessments and traditional neuroimaging analysis techniques.

abstract: M.Sc.


title: The influence of persistent genital arousal (PGA) on romantic relationships

subject:
Sexuality
Genital arousal
Relationships

abstract: Persistent genital arousal disorder (PGAD) is characterized by sensations of physiological genital sexual arousal that occurs in the absence of subjective feelings of sexual desire. Although partner factors have been examined in prior research among other conditions affecting the genital region and sexual response, to date no research has focused on the interpersonal context within which PGAD occurs. There are gaps in the current literature on (1) the relationship, sexual, and psychological well-being of individuals with PGAD who are in a relationship, (2) whether individuals disclose their symptoms to romantic partners, and (3) whether interpersonal variables (such as partner responses, symptom disclosure, and catastrophizing) are related to relationship adjustment and symptom severity. Seventy-six individuals (N = 62 women, N = 10 men, N = 2 Non-Binary, N = 1 Two-Spirit) with symptoms of persistent genital arousal (PGA), as well as 76 age- and sex-matched controls participated in a one-time anonymous online survey. Individuals with PGA reported significantly lower relationship and sexual satisfaction, greater sexual distress, and more symptoms of depression and anxiety compared to controls. Over three-quarters (85.5%) of the PGA sample disclosed their symptoms to their partners in some way. Greater supportive partner responses and lower symptom catastrophizing were related to better relationship adjustment among participants with PGA. Greater symptom catastrophizing also predicted greater PGA symptom severity. Partner responses were not related to PGA symptom severity. Results of the current study suggest that when one member of a couple experiences symptoms of PGA, there may be associated consequences for relationship, sexual, and psychological well-being. Although interpersonal factors have been linked to symptom severity in chronic pain and genital pain conditions, the results of the current study suggest that interpersonal factors may play a slightly different role in PGA symptom experiences and in the conceptualization of PGAD more broadly. Results and implications are discussed in the context of interpersonal models of sexual and relationship functioning.

abstract: M.Sc.


title: The Impact of Acute Social Stress on Approach and Avoidance Motivation in Individuals with Depression: An Examination of Behavioural and Neurophysiological Indices of Motivation

contributor:
Harkness, Kathryn
Psychology

subject:
Depression
Stress
Motivation
Frontal Alpha Asymmetry

abstract: Stress is considered proximal to the maintenance of depression. However, precise mechanisms linking stress to depression maintenance are largely unknown. Depression is characterized by decreased motivation for, and response to, reward. Further, both exposure to stress and subjective response to stress have been shown to negatively affect several reward-related processes in healthy individuals. The goal of the current study was to examine the impact of acute stress exposure and response on behavioural approach and avoidance motivation, defined as willingness to expend effort for reward/to prevent loss, and frontal EEG alpha asymmetry, a neurophysiological index of motivation. Depressed (n= 57) and non-depressed (n= 44) participants were randomized to social exclusion versus inclusion on a Cyberball task. EEG was recorded in 2-minute blocks immediately before and following Cyberball. Following Cyberball, participants completed the Need Threat Scale (NTS), as a measure of response to social exclusion, and a modified version of the Effort Expenditure for Rewards Task (EEfRT) that included both reward and loss trials. Individuals with depression showed lower approach and avoidance motivation on the EEfRT than healthy comparisons. With regards to social stress exposure, individuals in the Cyberball exclusion condition showed higher avoidance motivation compared to individuals in the inclusion condition. There was no significant effect of stress exposure on approach motivation, nor significant interactions between stress exposure and diagnostic group for either approach or avoidance motivation. With regards to stress response, there was a significant interaction between stress response and diagnostic group for both approach and avoidance motivation. Specifically, lower NTS scores (i.e., greater threat to fundamental needs in response to Cyberball) predicted lower approach motivation and higher avoidance motivation but only for individuals with depression. With regards to frontal alpha EEG asymmetry, as predicted individuals with depression showed lower relative left frontal asymmetry compared to healthy comparisons when controlling for comorbid anxiety symptoms. Contrary to hypotheses, across groups, individuals in the exclusion condition showed greater post-stress relative left frontal asymmetry compared to those in the inclusion condition. These findings are discussed in light of previous literature and with regards to study strengths and considerations.

abstract: PhD


title: A Study of Aspects of the Coupling of Flow and Sediment Transport for Sand and Gravel Dunes

contributor:
A.F. da Silva, Ana Maria
Civil Engineering

subject:
River dunes
Hydraulics
Sediment Transport

abstract:
This work investigates the coupling between flow, sediment transport and changes to geometry of river dunes. It aims to broaden the understanding of this coupling by examining: a) intrinsic differences between flow and sediment transport over equilibrium and non-equilibrium dunes; and b) whether the equations relating flow conditions to dune development and geometry developed for sand dunes are equally applicable to gravel dunes. To this end three novel laboratory experiments were carried out. Two experiments build upon a previous test by Wiebe (2007) in which equilibrium dunes were developed and then subjected to a sudden decrease in flow depth. The equilibrium dunes in the test under consideration were recreated and immobilized. For the first experiment this enabled the study of the flow field at equilibrium state, and just after the flow depth was suddenly decreased. In the second experiment a 2 cm layer of sand was placed over two of the dunes enabling the measurement of sediment transport for the aforementioned two flow conditions. For the third experiment three different flow conditions were run over a flat bed and the bed profiles were measured as gravel dunes developed and migrated. The findings of this work are as follows:
1)	No differences were found in the patterns of time-averaged velocity and turbulence characteristics over the equilibrium and non-equilibrium dunes which would explain the observed changes in dune geometry.
2)	An attempt was made to predict bed shear stress over the dunes. Fits were used to extend viscous stresses calculated by a RANS numerical model below the bed surface to the theoretical wall. Shear stresses calculated in this way exhibited significantly different patterns under equilibrium and non-equilibrium conditions and could be used to accurately predict bed changes. The validity of this method, however, has yet to be proven.
3)	The downstream derivatives of bed surface elevation and the bed-load rate was found to be proportional to each other at equilibrium state.
4)	The geometry and time of development of gravel dunes appears to be well predicted by equations previously developed for sand dunes while their wave spectra are not.

abstract: PhD


title: Nature or Nurture? Collisionless Evolution of Galactic Disc-Halo Systems

rights: Attribution-NonCommercial-ShareAlike 3.0 United States

subject:
Galactic Astronomy
Galactic Dynamics
Theoretical Cosmology
Numerical Methods
Astrophysics

abstract:
In this thesis, we develop and apply a novel algorithm to understand the evolution of stellar discs in ΛCDM cosmological haloes. Three main scientific areas are addressed: the effects of evolving stellar discs on their host haloes, understanding bar formation in cosmological settings, and the formation of vertical disc structure in response to the host halo.

First, we find that the presence of central concentrations of baryons in dark matter haloes enhances adiabatic contraction causes an overall modest reduction in substructure. Additionally, the detailed evolution of stellar discs is important for the inner halo density distribution. However, properties of the halo such as the subhalo mass function are broadly unaffected by the evolution of a realistic stellar disc.

Next, we find that stellar bars invariably form in Milky Way-like galaxies. The strength of these bars is less dependent on properties like the dynamical temperature of the disc in a cosmological setting. Instead, the disc thickness plays a leading
role in determining the overall bar strength. Our discs undergo notable buckling events, yielding present-day pseudobulge-disc-halo systems. We show that these are qualitatively similar to the observed Milky Way.

Finally, we show that a wide variety of vertical structure forms when stellar discs are embedded in cosmological haloes. We further show that through a variety of mechanisms, similar vertical structure is excited. By examining twelve simulations of
discs in cosmological haloes, we show that the Sgr dSph need not be as massive as 10^{11} solar masses to be consistent with observed vertical structure in the Milky Way. In fact, the recent buckling of the Milky Way’s bar and its present interaction with the LMC are more likely culprits for some of the observed structure in the Milky Way’s thin disc.

abstract: PhD


title: The Effect of In Utero Benzene Exposure on Fetal NF-KB Cell Signalling in CD-1 Mice

contributor:
Winn, Louise M
Biomedical and Molecular Sciences

subject:
Leukemia
Women's Health
Benzene
Children's health

abstract: In utero exposure to benzene, a known carcinogenic environmental toxicant, is associated with the development of childhood leukemia. We have previously demonstrated that in utero exposure to benzene in CD-1 mice can alter the expression of the transcription factor NF-KB, which regulates genes involved in cell proliferation and programmed cell death, however, a full characterization of benzene’s effects on fetal NF-B is still needed. Since NF-KB regulates genes involved in cell proliferation, inappropriate activation can result in the proliferation of damaged cells potentially leading to the development of leukemia. We hypothesize that benzene metabolism in the maternal liver leads to fetal changes in NF-KB signalling. To test this hypothesis, pregnant CD-1 mice were exposed to 200 mg/kg benzene or its vehicle control on gestational days 8, 10, 12, and 14. Dams were sacrificed at 1, 2, 6, or 24 hours after the last benzene dose. Fetal livers were collected, and immunoblotting was done to assess changes in protein levels of phospho-p65, phospho-p38-MAPK, p50, and inhibitor of NF-KB (IKB-α). Results show that after in utero benzene exposure, protein levels of nuclear p50, phospho-p65 and phospho-p38-MAPK did not change significantly after benzene treatment but protein levels of IKB-α significantly increased 6 hours after the last benzene dose. However, there were no observed changes in the mRNA level of IKB-α. There were also no observed significant changes in the DNA binding activity of NF-KB following in utero benzene exposure. In conclusion, these results suggest that in utero benzene exposure does not alter NF-KB signalling in CD-1 mice fetal liver aside from the increased IKB-α protein levels. Further studies should be done using techniques that do not possess the limitations in this study.

abstract: M.Sc.


title: Explicit-Implicit Attitudinal Ambivalence in Romantic Relationships:  Antecedents and Outcomes

contributor:
Fabrigar, Leandre
Psychology

subject:
Ambivalence
Explicit-Implicit Ambivalence
Relationships

abstract: Previous research has shown that the attitudes individuals hold towards their romantic partner often greatly impact relationship outcomes. Traditionally, attitudes towards one’s romantic relationship were assessed using explicit measures. Implicit measures however recently gained popularity owing to the fact that they have been demonstrated to provide attitudinal information beyond that which is communicated through explicit measures. Given the recent advent of the incorporation of implicit measures into relationship research, and previous conceptualizations that framed attitudes as bipolar, relatively few studies have assessed both explicit and implicit attitudes, let alone explicit-implicit ambivalence. Those that have, have shown explicit-implicit attitudinal ambivalence to influence thoughts and judgments, and predict behaviour/behavioural intentions. Few studies however have taken an interest in the interplay between explicit and implicit measures, and whether antecedents and outcomes differ as a function of a participants’ explicit-implicit ambivalence profile. The present research extends previous literature by examining the antecedents and outcomes specifically associated with each of the two possible attitudinal ambivalence profiles in a relationship context. This study is therefore unique in its’ intentions to investigate and contrast the unique psychological underpinnings of differing relationship-specific ambivalence profiles, while using a never-before combined selection of explicit measures, implicit measures, antecedent and outcome variables. Results indicated significant, positive correlations between explicit measures. Conversely, correlations among the implicit measures were extremely weak. With regards to the explicit-implicit measure correlations, one of the explicit measures consistently produced significant correlations when combined with each of the implicit measures. Both antecedents and outcomes were differentially associated with each of the two ambivalence profiles. Individuals who were low in ambivalence and attachment-related avoidance were more likely to display explicit-implicit ambivalence such that their attitudes were more positive on the implicit measure than the explicit measure. Further, it was when avoidance and ambivalence decreased that the explicit-implicit discrepancy increased.

abstract: M.Sc.


title: Does Gerontological Nursing Education and Personal Attitudes Toward Older Adults Influence New Nurses’ Intentions to Work in Aged Care Settings?

contributor:
Sawhney, Monakshi
Nursing

subject:
New Nurse
Nursing Education
Aged Care Nursing
Gerontology

abstract:
Background: In Ontario, the older adult population is steadily increasing, and the healthcare system is not equipped to effectively care for their needs. This is evidenced by the large number of Alternative Level of Care (ALC) beds within hospitals, and lengthy wait times for admission into a Long-Term Care (LTC) facility. As new LTC spaces are created, new nurses will be critical members of the healthcare team required to care for these patients. However, there is no current evidence about the intentions of registered nurses (RNs) and registered practical nurses (RPNs) who are newly registered with the College of Nurses of Ontario (CNO) to work in aged care facilities. There is also no data regarding their attitudes toward older adults, or how their nursing education influences these variables.

Aim: The aim of this study was to examine how pre-licensure geriatric nursing education and personal attitudes toward older adults influence newly registered RNs’ and RPNs’ intentions to work in aged care.

Method: A descriptive, cross-sectional design was used. A questionnaire that included the Kogan’s Attitudes Toward Old People (KAOP) Scale was mailed to newly registered RNs and RPNs across Ontario (n=1103).

Results: Participants (n = 181) reported positive attitudes toward older adults (KAOP mean score = 166, SD = 24); however, their attitudes were not influenced by their education, and did not influence their intention to work in aged care. Forty-five percent of participants reported that their gerontological nursing education provided them with the knowledge, skill and judgement to care for the older adult population, and 14% of participants intend to work in an aged care setting within the next five years. Participants’ intentions to work in an aged care setting was positively associated with having multiple gerontological clinical placements (ß = 1.76, p < 0.05), and having a clinical placement in a LTC setting (Odds Ratio (OR) 2.30; p < 0.01).

Conclusion: The findings support the need to provide nursing students with high quality gerontological nursing curriculum and clinical placements. Qualitative research is recommended to understand why new nurses in Ontario may not intend to work in aged care settings.

abstract: MNSc.


title: The Influence of the Level of Representation of Information on Belief Formation and Change

subject:
Level of Representation of Information
Attitudes
Persuasion
Attitude Structure
Belief Formation
Belief Change

abstract:
The upward extrapolation of information from an individual to a category and the downward extrapolation of information from a category to an individual are pervasive social-cognitive processes. People can form beliefs using upward and downward extrapolation processes, as well as by learning information directly about an object (i.e., a process with no extrapolation). These three processes can be conceptualized as levels within the variable: the level of representation of information. Although extrapolation processes have been long recognized in many literatures, level of representation has been largely disregarded as a property of attitude structure and a property of persuasive messages. This program of research consisted of four studies that examined the effects of level of representation on persuasion. Studies One and Two examined upward extrapolation processes. Study Three examined downward extrapolation processes. Study Four examined upward and downward extrapolation processes simultaneously.
The findings supported several key principles. First, messages represented at the level of target are generally the most persuasive. Second, messages become decreasingly persuasive as they require more extreme extrapolation processes. Third, the persuasiveness of messages is contingent on the level of representation at belief formation about the target. Persuasive messages represented at the target level are similarly effective irrespective of the level of representation at belief formation, while the persuasiveness of messages represented at non-target levels varies across different levels of representation at belief formation. When the initial beliefs about a target are based on target-level information, persuasive messages represented at a non-target level are generally less effective than a message represented at the target level. However, when the initial beliefs about a target are based on information that requires an extrapolation process that is equally as extreme as or more extreme than the non-target-level message at persuasion, the non-target-level message becomes more effective and the difference in effectiveness between the non-target-level message and the target-level message diminishes. Overall, this program of research has demonstrated that level of representation should be seriously considered as a property of attitude structure and a property of persuasive messages, and thus, should be further investigated as such.

abstract: PhD


title: Narrowband jamming mitigation in vector-based GPS software defined receiver

contributor:
Noureldin, Aboelmagd
Electrical and Computer Engineering

subject:
GPS
Jamming mitigation
wavelet packet transform
fast orthogonal search

abstract:
The last decade has witnessed a growing demand for reliable, continuous and accurate positioning and navigation with the growth of a wide range of new applications that rely predominately on Global Navigation Satellite System (GNSS), including Global Positioning System (GPS). The widespread of these applications and their integration in many aspects in our day-to-day activities made GNSS receivers appealing targets for disruption or jamming. Although, GPS signals employ direct sequence spread spectrum (DSSS) modulation that provides some level of robustness to intentional
and unintentional radio frequency (RF) interference; GPS signals are vulnerable to interference and jamming as they reach the receiver antenna below the noise floor.
A jamming signal can degrade the signal-to-noise ratio (SNR) which results in deterioration in the acquisition, tracking and navigation stages within the receiver. The resultant degradation or interruption of the GPS service due to signal jamming could lead to significant consequences and risks. Loss of time synchronization, disruption of communication and network operations, and potential loss of life are examples of these consequences, to name a few. The primary objective of this thesis is to provide a GPS-based reliable and uninterrupted positioning solution in the presence of interference signals, particularly continuous wave (CW) and swept continuous wave (SCW) signals. To tackle this challenge,  first, a robust vector-based software defined receiver has been implemented, and its performance was assessed in degraded signal conditions including the presence of interference. Second, two pre-correlation jamming mitigation techniques are proposed. The first technique is based on transforming the incoming signal into time-scale domain using wavelet packet transform (WPT), in which the jamming signal can be better identified and isolated. The second is a high-resolution spectral analysis technique that is based on fast orthogonal search (FOS), in which the jamming signal is modeled using a set of candidate functions and then suppressed from the received signal. These two techniques were augmented with the vector-based software receiver and their performance was assessed using various static and dynamic scenarios.

abstract: PhD


title: Testing Photometric and Kinematic Algorithms to predict Next-Generation Telescope Survey Statistics

rights: Attribution-NonCommercial-NoDerivs 3.0 United States

subject: Astronomy Galaxies

abstract: Reconciling the velocity function of dark matter halos in collisionless simulations with those derived observationally requires understanding how galaxies are embedded in their dark matter halos. Widefield neutral atomic hydrogen surveys with Square Kilometre Array pathfinders such as WALLABY on the ASKAP telescope will address this issue since they will resolve the kinematics of representative samples of galaxies beyond their optical disks. These statistical samples afford constructing a velocity function out of resolved galaxies, including those with distorted kinematics that recent hydrodynamical simulations suggest make up a significant fraction of nearby systems. To do so, however, the kinematics of the thousands of poorly resolved galaxies that will comprise the majority of WALLABY detections will need to be modelled using novel techniques, and we will require ancillary photometric inclination estimates. Several new codes have been developed to model kinematics, but few have been tested in the marginally resolved regime. We explore our ability to constrain photometric components using DiskFit and galaxies from the Spitzer Survey of Stellar Structure in Galaxies, determining that we can estimate ellipticity correctly to within δƐ=0.083. Then, using empirical scaling relations for disk galaxies in the local volume, we generate an extensive suite of resolved, WALLABY-like synthetic galaxy observations and use them to test how well galaxy kinematics can be recovered using the Fully Automated TiRiFiC 3D modelling code. We then simulate a mock WALLABY volume of resolved galaxy detections, use our model-fitting results to determine the reliability with which the kinematics of each can be recovered, and predict the resolved galaxy velocity function that WALLABY will measure. Our ability to model galaxies with fewer than five beams across their major axes significantly increases the number of resolved detections that could contribute to the sample. We discuss how the predicted WALLABY velocity function is impacted as the sample size grows to contain these more poorly resolved galaxies, and find that we can recover the velocity function down to 25 km/s, an improvement upon the predicted lower limit of  50 km/s based on the limitations of legacy algorithms.

abstract: PhD


title: An Historical Examination of the Secondary Mathematics Curriculum in Ontario Through Two Lenses: Curriculum Policy Documents and Reflections of Leaders in the Field

contributor:
Colgan, Lynda
Education

subject: mathematics curriculum Ontario

abstract:
The secondary mathematics curriculum in Ontario has gone through many revisions and renewals during the past 60 years. Current curriculum and policy documents are readily available, yet previous documents are not easily accessible. There is a dearth of literature on historical changes to the Ontario secondary math curriculum, especially from the perspective of the mathematics education leaders. By performing a document analysis of historical secondary mathematics curriculum in Ontario and then interviewing mathematics leaders who have been involved in several change/revision processes, this descriptive study seeks to document the changes to and influences on the Ontario secondary mathematics curriculum since the 1960s.

	This study identified keys trends in changes to Ontario mathematics curriculum documents. These trends include an increased focus on teaching methodologies within the document, removal of topics such as conics and proofs with the reduction of the secondary program to four years and an overall increased focus on calculus.  By contrasting document changes to both previous literature and interviews conducted in this study, possible triggering events, such as mathematical movements or new political parties elected, were identified for each curriculum revision. By comparing and contrasting experiences of leaders with existing literature suggestions for future curriculum revisions processes are proposed such as a provincial scoping survey prior to the start of the writing process and sufficient time for field testing and implementation.

abstract: M.Ed.


title: Chronic Health Conditions in the Classroom: A Pan-Canadian Assessment of Adolescent Psychosocial Functioning

contributor:
Berg, Derek
Education

subject: health adolescence school psychosocial

abstract: Due to a variety of factors (e.g., absence from school, being physically unable to take part in certain activities), students with Chronic Health Conditions (CHCs) are at a greater risk of low academic achievement and less fulfilling social relationships than their otherwise healthy peers (Hoffmann et al., 2018; Thies & McAllister, 2001). Teachers’ insufficient understanding of the psychosocial functioning (i.e., affective, cognitive, and behavioural characteristics) of students with CHCs results in a lack of educational programing to suit those students’ health and educational needs, compounding the risk of low academic achievement and less fulfilling social relationships (Hopkins & Hughes, 2016). The purpose of this research is to establish patterns of psychosocial functioning in order to inform teacher practice, and It has been guided by the following research question: Are there significant differences in psychosocial functioning (affective, behavioural, and cognitive) of Canadian adolescents with and without CHC?  The methods involved the development of a model of affective functioning, one of the three domains of psychosocial functioning. The model comprised three factors: interpersonal home (feeling emotional support, understood, trusted, happy, listened to), interpersonal school (feeling trust, belonging, fairness, a nice place accepted), and general intrapersonal (feeling left out, lonely, hopeless, and the desire to be someone else), which speak to those inward feeling. Follow-up t-tests that adolescents with CHCs functioned significantly poorer than adolescents without CHCs on all affective factors, and ANOVAs revealed that specific affective functioning varied significantly among the types of CHCs. Additionally, sex and grade are significant factors in reported affective functioning. Measures should be taken to help support the affective functioning of adolescents with CHCs in the school environment. It is recommended that efforts should be taken to support students’ sense of belongingness, as it should in turn foster affective psychosocial experiences. Additionally, teachers should be made knowledgeable of students who are more at-risk of poor affective psychosocial functioning, namely, females, those in higher grades, and those with multiple CHCs.

abstract: M.Ed.


title: Studying the Gas Usage and Price of Transactions in the Ethereum Blockchain Platform

contributor:
Hassan, Ahmed
Computing

subject:
Mining
Smart Contracts
Ethereum
Blockchain
Gas
Gas Limit
DApp
Transaction Fee
Gas Price

abstract:
Ethereum is a blockchain platform that hosts and executes general-purpose computer programs known as smart contracts. Users execute smart contracts by sending transactions to one of the functions of the contract. The execution of smart contracts in Ethereum has a cost that is measured in Gas unit. Executing a function of a smart contract burns a certain amount of gas units (a.k.a., gas usage). The total gas usage depends on how much computing power is necessary to carry out the execution of the function. Ethereum follows a free-market policy for deciding the transaction fee for executing a transaction. More specifically, users choose how much they are willing to pay in cryptocurrency for each unit of gas (a.k.a., gas price). Miners process transactions to gain mining rewards, which come directly from the paid transaction fees by users. However, neither the user nor the miner know, beforehand, the gas usage of a transaction. In this thesis, we analyze the Ethereum transaction data spanning between Oct. 2017 and Feb. 2019 (the Byzantium period) to conduct two studies that examine how gas usage and price impact the transaction processing dynamics of the Ethereum blockchain platform.

In our first study, we examine the strategies that are adopted by miners to prioritize transactions, the stability of the gas usage of contract functions, and whether the gas usage of a contract transaction can be predicted within a reasonable margin.  We observe that most miners follow the default strategy for prioritizing transactions (which solely relies on gas price), a significant amount of contract functions have a very stable gas usage history, and it is possible to provide a real-time estimation of the gas usage of a transaction for these contracts with a median Adjusted RSquared of 0.86.

In the second study, we focus on understanding gas prices. We analyze how users commonly set gas prices and whether the contracts that are involved in user-to-contract transactions influence gas prices. Subsequently, we build a regression model to discover the factors that are strongly associated with the gas price of transactions. We observe that the gas prices set by users assume a wide range of values, vary considerably over time, and change based on the user. We also observe that the gas price of user-to-contract transactions differ significantly across contracts and functions. Lastly, we observe that different factors are more strongly associated with gas prices at different times.

Our findings can help researchers to focus on the vulnerabilities of the current gas mechanism in their future work, provide developers insights on how to improve their decentralized applications (DApps) regarding transactions, motivate users to make an informed decision when issuing a transaction, and help miners to adopt optimized mining strategy.

abstract: M.Sc.


title: Testing Models of Reactive Systems

contributor:
Dingel, Juergen
Computing

subject:
Model-driven Engineering
Concolic Testing
Reactive Systems
State machine
Testing
Real-time Embedded Systems

abstract:
Testing models of modern Real-time Embedded (RTE) systems is not straightforward
due to timing constraints, numerous if not infinite possible behaviors, and complex
communications between components. Software testing tools and approaches that
can generate test cases to test these systems are therefore important. Many of the
existing automatic approaches support testing at the implementation level only. The
existing model-level testing tools either treat the model as a black box (e.g., random
testing approaches) or have limitations when it comes to generating complex test sequences (e.g., symbolic execution). This thesis presents different test case generation
techniques for models developed in UML-RT, a UML profile and a domain specific
language for modeling RTE systems. We present a novel approach and tool support
for automatic unit testing of UML-RT models by conducting concolic testing, a hybrid
testing technique based on concrete and symbolic execution. Our technique conducts
automatic concolic testing in two phases. In the first phase, the model is isolated from
its environment, transformed to a testable model and integrated into a test harness.
In the second phase, the harness tests the model concolically and reports the test
execution results.
To make the test case generation efficient for UML-RT models, we present a novel
slicing technique and its tool support. The slicer takes the input model and a criterion,
and constructs a slice by taking into account the input criterion. The slice contains
only those (behavioral and structural) elements of the original model that depend on
the input criterion. Therefore, a slice is possibly a smaller model (compared to the
original model) that can make the test case generation more efficient.
We describe implementations of each of the techniques in the context of PapyrusRT, an open source Model Driven Engineering (MDE) tool based on the modeling
language UML-RT, and report the results of applying our techniques to a set of
benchmark models to validate our approach.

abstract: PhD


title: Nigeria’s Internally Displaced Women: The need for decent shelter

contributor:
Goebel, Allison
Environmental Studies

subject:
Insurgency
Internal Displacement
Internally Displaced Person(s)
Women
Vulnerability
Humanitarian Response
Accessibility
Shelter
Wellbeing
Sustainable Development

abstract: Since 2009, Nigeria, Africa’s most populous country, has been in a serious humanitarian crisis emerging from insurgency headed by militant jihadist organization: Boko Haram. The group has carried out deadly attacks on civilians in northeast Nigeria leading to mass internal displacement and forced migration of affected persons in the region to more stable areas of the country. The conflict has done abysmal damage to the region and nation, causing thousands of deaths and dispossessing over 3 million people of their properties and livelihood. Women and children remain hot targets of the group’s numerous abductions, torture and sexual violence both during and post active attack periods. These issues have forced many to flee their communities, seeking safety in Internally Displaced Persons (IDP) camps cross- country. However, a majority of the camps are in a deplorable state and grapple with overcrowding, poor living conditions, insecurity, environmental health risks and other dangers. The aim of this study is to explore how these issues affect women’s wellbeing, particularly in Durumi IDP camp, Abuja. The end goal of the study is to find crucial gaps in the camp’s conditions and operations, and develop strategies/ recommendations that adhere to sustainable approaches in addressing the pressing living conditions in the camp, particularly decent shelter.

abstract: M.E.S.


title: Something Got Into Their Minds: The Rise of Radicalization Discourse in Canada

contributor:
King, Samantha
Kinesiology and Health Studies

subject: Radicalization, Sport-For-Deradicalization, Canada, Discourse Analysis, Foucault, Affect,

abstract: This dissertation examines the rise of radicalization discourse in Canada. Drawing on postcolonial theories of Orientalism and affect, I contend that radicalization is a racially-charged concept that characterizes anti-Western violence in ways that relieve Western states of culpability for their colonial provocations. Evidence of such provocations is diluted through prevailing radicalization discourses that inform counter-terrorism frameworks and shape popular understandings of terrorism. Such frameworks rely heavily on race-based assumptions painting Muslim-looking subjects and communities of colour as especially susceptible to extremism and terrorist violence. These assumptions construct an ostensibly scientific framework for radicalization that transforms mundane behaviours into “indicators” of suspiciousness and risk amongst people of colour. This leads to what I term a “pretrapment” logic whereby thoughts and behaviours racially tagged as “Muslim” are used to justify pre-emptive interventions designed to halt a future terrorist attack. Additionally, radicalization discourse paints Muslim communities as “suspicious allies” that are perceived as both breeding grounds for radicalization and necessary agents of surveillance for the state. Against this backdrop, sport is constructed as a key catalyst for deradicalization interventions on susceptible subjects who may otherwise slip into violent, extremist thoughts and action. Sport’s role in deradicalization helps augment colonial discourses that align with imperial myths of benevolence, western characterizations of Muslim culture as universally misogynistic, and the construction of Muslim-looking people as constant outsiders within western civilization.

abstract: PhD


title: Bioremediation of arsenic and cadmium in a Populus tremula x Populus alba mutant

contributor:
Regan, Sharon
Biology

subject: Bioremediation Phytoremediation Poplar Arsenic Cadmium

abstract: The use of plants to remediate contaminated lands is of growing interest to the scientific community because of its ease of implementation, cost effectiveness and ability to stabilize contaminated soils. A novel Populus tremula x Populus alba mutant named fuzzy with an increased trichome density, an elevated growth rate, enhanced pest resistance and a predicted root phenotype was investigated for its ability to tolerate and accumulate arsenic and cadmium in soil. The chlorophyll, hydrogen peroxide and proline contents of fuzzy tissues were assayed, its tissue metal content was measured using ICP-MS and its wet biomass was quantified. Transgenic Arabidopsis thaliana overexpressing homologous gene of that overexpressed in the fuzzy poplar were grown on gel media and their roots were measured to corroborate the root phenotype of fuzzy poplars. The fuzzy poplar was found to have lower levels of hydrogen peroxide in its tissues after arsenic and cadmium exposure than control poplars, suggesting it has a reduced oxidative stress response when exposed to high levels of arsenic and cadmium. This low hydrogen peroxide content was not due to reduced arsenic and cadmium accumulation in fuzzy trees, as they did not accumulate different amounts of arsenic or cadmium than control plants. Proline and chlorophyll levels were not significantly different between metal treatments, or between fuzzy and control poplars. fuzzy poplars exhibited significantly higher root biomass than control poplars, and transgenic Arabidopsis thaliana overexpressing a homologous gene to the one that causes the fuzzy phenotype had significantly longer roots than control plants. All poplars exposed to arsenic and cadmium in this trial contained the majority of these compounds in their tissues in roots. The root biomass phenotype, low hydrogen peroxide content and root metal accumulation in the fuzzy poplar make it an ideal candidate for bioremediation and soil stabilization of contaminated soils.

abstract: M.Sc.


title: Simulating solute transport in discretely fractured rocks: Computational limitations and a hybrid method

contributor:
Novakowski, Kent
Civil Engineering

subject: Solute transport, discrete fracture networks, hydrogeology

abstract:
To investigate the computational limitations arising when simulating large-scale groundwater flow
and solute transport using a 3D control volume finite element model (the FE model) in discrete-fracture
mode, numerical simulations were matched to a semi-analytical solution for radial divergent
solute transport in a single fracture. Discretization parameters and computation times were
compared for two sets of simulations. Depending on the model parameters, transport simulations
in the FE model can take longer to compute with parallel versus serial processing. The transport solution
was the largest limiting factor with respect to computational cost for our models. Transport
computations, for example, took 86-98% of the total computation time, and the relative flow and
transport times changed little with increasing scale. Next, an efficient hybrid numerical-analytical
method (the NA method) for simulating solute transport in 2D fracture networks is proposed. The
NA method can be used to compute solute breakthrough curves in a 2D network of fractures of
varying aperture and fluid velocity by applying the Tang et al. (1981) solution to an equivalent fracture
pathway (EFP) which is generated by a numerical model. The NA method was verified at
three different transport scales (i.e., 10m, 50m and 250m) using a range of realistic fracture apertures,
matrix porosities and hydraulic gradients, by comparing simulated breakthrough curves to
those generated by the FE model. Solute dilution can be accommodated by scaling a breakthrough
curve using discharge ratios in the fracture segments before and after dilution. The validity of
this method depends on the ratio of the Péclet number and the matrix porosity, which can serve
as an indication of the cases in which the NA method will be valid for a given fracture spacing
and transport distance. A 2k factorial analysis was also conducted which shows that increasing the
number of fracture intersections diminishes the ability of the NA method to match the FE model.
Simulations of realistic 2D fracture networks however show that in natural fractured rock systems,
the NA method could be a useful tool to simulate solute transport at an up to 85% reduced
computational cost.

abstract: M.A.Sc.


title: Procedures to Analyze and Design Decentralized, Distributed Sensor Networks for Change Detection

contributor:
Blostein, Steven
Electrical and Computer Engineering

subject:
Quickest Change Detection
Sensor Networks
Wireless Communications
Distributed Quickest Change Detection
Sequential Hypothesis Testing
Electrical Engineering

abstract:
The emergence of the Internet of Things (IoT) has reinvigorated interest into the distributed quickest change detection problem within wireless sensor networks. Although a number of system designs addressing this problem exist in literature, the vast scale of IoT has highlighted limitations of existing methods when adapted to large networks. The purpose of this thesis is therefore to investigate and propose both system designs and design methodologies that perform well in large networks.

Numerical analysis techniques are developed that allow for accurate threshold design of the Sequential Probability Ratio Test (SPRT) and Cumulative-Sum (CUSUM) procedures with respect to desired error metrics. Tests designed using these procedures are compared with those using Wald’s approximation to highlight the impact of sequential test overshoot on test design. These techniques are shown to also provide insight into the operation of these procedures over time.

Leveraging these techniques, two system designs are proposed to solve the distributed quickest change detection problem. With large sensor networks in mind, multiple simultaneous transmissions within the network are permitted and analyzed uniquely by a fusion center (FC), and the problem of limited bandwidth is considered.

These designs use the CUSUM procedure at local sensors to quantize local sensor observations into binary summary reports that are transmitted to the FC, indicating the outcome of each local sensor's CUSUM in each time slot.  Probability mass functions describing the probability of the fusion center receiving one or more reports from local sensors in each time slot are computed using the developed CUSUM analysis techniques. Accurate characterization of the local sensor reporting process allows the fusion center to implement procedures based on Bayesian and minimax formulations to the quickest change detection problem.

It is shown that using the minimax-based system design may perform well when a number of assumptions are satisfied. This design is capable of scaling to large networks and a methodology by which global and local thresholds may be chosen to meet a desired false alarm rate constraint is proposed. It is also shown that the performance of this design can be numerically computed for different choices of system design variables.

abstract: M.A.Sc.


title: Efficient Structured Light Pattern Using Inverse Rectification

contributor:
Greenspan, Michael
Electrical and Computer Engineering

subject:
Projector
Camera
Epipolar Lines
Fast
Homography
Calibration

abstract: This thesis presents inverse rectification, a novel method for establishing correspondence in depth estimation. The rectifying homography of the projector-camera pair is used to warp a pattern of vertical dash features. The pattern imparts upon the system the property that projected features will fall on distinct conjugate epipolar lines of the rectified projector and acquired camera images. This reduces the correspondence search to a trivial constant-time table lookup, and leads to robust and extremely efficient disparity calculations. A projector-camera range sensor is developed based on this method, and is shown experimentally to be effective, with bandwidth exceeding some existing consumer-level range sensors.

abstract: M.A.Sc.


title: Molecular Orientation in Large-Amplitude Oscillatory Shear (LAOS) of Complex Fluids

contributor:
Giacomin, A. Jeffrey
Chemical Engineering

subject:
Rheology
Complex Fluids
Polymers
Oscillatory Shear
Rigid Dumbbell Theory
Molecular Modelling
Small-Angle Light Scattering
Wormlike Micelles

abstract: Polymer rheological properties are important to modern manufacturing, and though polymers have been studied for decades, we still do not fully understand how polymers flow. Subjecting a polymeric liquid to oscillatory shear flow is a common method for probing polymer rheology. Oscillatory shear flow provides rheologists with necessary information on the dynamic behavior of polymers. This thesis aims to deepen our understanding of polymer flow by generating a comprehensive modernization of molecular theories that predict polymer behavior during oscillatory shear. Additionally, this work provides a detailed investigation of rigid dumbbell macromolecular theory by dissecting the orientation distribution function to find the pieces that contribute to important rheological properties like the shear stress response and the normal stress differences. Orientation is the source of all rheological property predictions for rigid dumbbell theory. Thus, this thesis also provides a comprehensive experimental analysis of macromolecular orientation. Specifically, light scattering measurements are conducted on a wormlike micelle solution that is simultaneously subjected to large-amplitude oscillatory shear. These light scattering measurements provide information on micelle orientation throughout an oscillatory shear cycle. We compare these experimental orientation results with the orientation predictions of rigid dumbbell theory. We find that rigid dumbbell theory cannot capture all aspects of wormlike micelle rheology during large-amplitude oscillatory shear (LAOS) flow. Rigid dumbbell theory is especially incapable of predicting scattering caused by concentration fluctuations arising from micelle breakup, when the flow changes direction. Additionally, rigid dumbbell theory predicts orientations that are entirely out-of-phase with the measured orientations, such that there are no times during an oscillatory shear cycle when rigid dumbbell theory and orientation measurements match. We complete this study by blending different light scattering theories to formulate a descriptive model for our results.

abstract: PhD


title: Manufacture of vertical walls with asymmetric incremental sheet forming

subject:
SPIF
TPIF
Geometrical errors
Vertical walls
Cost analysis
Multi-stage

abstract:
Single point incremental forming (SPIF) is a dieless sheet metal forming technique that can manufacture customised sheet metal components in a cost-effective manner. However, the process is still in the developmental phase and hasn't been utilised industrially due to low geometrical accuracy, fracture at high wall angles and long cycle times. The goals of this research are to study the feasibility of the already existent strategies to eliminate geometrical errors and enhance formability and to, introduce a methodology to successfully generate vertical walls with the least geometrical errors and thickness variation within the manufactured component.

 The impact of friction on sheet interface and formability is reported by recording the temperature obtained by increasing the tool rotation speed and feed rate. A flat tool is used in the study and an upper limit of the tool rotation speed is reported. The limit is much lower than the hemispherical tool reported in the literature and two heat generation zones is the justification. High tool rotation speed and feed rate are found to reduce the geometrical errors but still are unacceptable.

Multi-stage strategies such as the conventional downward, DDDU and IO-OI are implemented to manufacture a C-channel designed to support a plane fuselage for vibration testing. Tunnel strategy is also employed. Vertical walls are only conceivable using a conventional downward strategy and a series of steps followed for the toolpath development are reported in the form of an algorithm. The results show that the developed component is affected by severe geometrical inaccuracies and extreme thickness variation.  Cost analysis reveal high costs associated with multi-stage forming in the design stage.

Finally, it is concluded that cost-effective and industrially acceptable flat base geometries are inconceivable through SPIF. The apparatus of Two Point Incremental Forming (TPIF) is modified and a new tool path strategy is developed to manufacture the vertical walls. The results show that the novel strategy is capable of manufacturing vertical walls with much lower thickness variation and geometrical errors. The developed method is cost-effective and easy to implement but requires a die.

abstract: PhD


title: Social Media and Law Enforcement: A Study on the Adoption and Use of Social Media Monitoring in Canada

contributor:
Lyon, David
Sociology

subject:
surveillance
social media
police
social media monitoring
canada

abstract: Police agencies globally now have access to several technologies that monitor social media, exploiting its data and content for investigative purposes. Such practices fit into larger discussions of policing shifting towards more proactive methods of crime control that seek to pre-empt crime and disorder. This exploratory research draws on 15 interviews from members of law enforcement from two local police agencies in Southern Ontario (referred to as ‘metropolitan’ and ‘medium-sized’) in order identify how local police in Canada monitor social media and what justifications prompted these agencies to do so. What this research study reveals is that social media monitoring needs to be understood in a context of larger socio- cultural, political and economic developments of late modernity, and in particular, growing concerns over risk (Garland 2001), rather than merely internal policing conditions. Such developments have shaped police adoption and use of social media monitoring. This research study also reveals that social media monitoring involves the use of automated and/or manual searching practices used to exploit social data and/or its content. These are two different sets of practices that are distinguished as ‘manual’ and ‘automated’. The former is linked to the exploitation of content, while the latter is linked to the exploitation of data. More often than not, they operate concurrently.  Third party software enable automated searching practices and includes both purchased and open source software, while manual searches include the use of built-in search features within social platforms. Police often monitor social media for a specific purpose, or to respond to an external complaint. The practice can be either continuous, or targeted. Social media is often used in targeted ways to proactively monitor the so called ‘usual suspects’ (Sanders and Hannem 2012). It is used in continuous ways to monitor major events including student ‘keg parties’ and political demonstrations. Social media monitoring may enable more (cost)efficient ways to keep tabs on individuals and to ‘socially sort’ (Lyon 2002) users in order to identify ‘problem populations’. Such surveillance practices further add to a growing ‘culture of control’ (Garland 2001) that has reshaped criminal justice institutions and crime control policies.

abstract: M.A.


title: Causal Uncertainty and Romantic Relationships

contributor:
Jacobson, Jill
Psychology

subject:
causal uncertainty
romantic relationships

abstract:
Causal uncertainty (CU) is a social cognitive construct where individuals believe that they may not accurately understand the cause and effect nature of social events (Weary & Edwards, 1994). Research examining how CU in stranger, roommate, and friendship dyads has demonstrated that CU is associated with negative perceptions of these relationships (i.e., decreased liking), but the research on CU and romantic relationships is limited (i.e., Boucher, 2015; Needham, 2015). Therefore, I conducted three studies to examine how CU is associated with conflict conversations concerning a recent issue (Study 1), conflict conversations about why a recent argument took place (Study 2) and relationship variables over time (Study 3).
In Study 1, data were collected from 100 romantic dyads who engaged in a conversation about a recent issue in their relationship. I used the Actor-Partner Interdependence Model (APIM) and found a significant CU actor by CU partner interaction. Examining this interaction further I found that at higher levels of partner CU, higher actor CU was associated with viewing a conflict conversation as more effective (p = .039). Whereas, at lower levels of partner CU, higher actor CU was associated with perceiving the conversation as being less effective (p = .023).

In Study 2, data from 73 romantic dyads were used to examine perceptions of two conversations about why their last disagreement took place. APIM analyses demonstrated that higher actor CU was associated with finding both conversations about why a recent argument took place as less appropriate (ps ≤ .002).

In Study 3, I examined several relationship variables over an approximate 8-week period for 533 undergraduates. I conducted linear regression analyses using CU scores at Time 1 to predict Time 2 dependent relationship variable scores, controlling for relationship variable scores at Time 1.

Higher causal uncertainty was associated with greater belief that disagreement within a relationship is unhealthy. Further research focusing on this belief could help untangle how high causally uncertain individuals engage in conflict conversations and implement conflict coping strategies. In addition, research could help disentangle when appropriateness versus effectiveness are important for high causally uncertain individuals to successfully navigate a conversation.

abstract: PhD


title: Beyond the Selfie: self, time, and visibility in young people’s engagement with social media

contributor:
Hand, Martin
Sociology

subject:
Youth
Visual Images
New Media Technologies
Self-Identity
Social Media

abstract:
Over the last ten years, the use of smartphones and social media has become a highly significant aspect of communication. The convergence of interconnected communication systems, handheld screens, social media platforms, and images has prompted scholarship around the digitally-mediated nature of self-presentation, performance, and everyday interaction. Young people, in particular, are thought to live increasingly ‘mediated lives’ where visual social media now provide the context for the most basic forms of self-understanding and sociality.

In this context, this dissertation examines how young people’s routine use of visual social media is shaping their sense of self and their perceptions and experiences of digitally-mediated visibility. The ways in which high-school and university students (aged 14-22) access Facebook, Instagram, and Snapchat through smartphones as part of daily activities form the key context for examination. The dissertation provides insight on the following: 1) How and in what ways the production, curation, and circulation of images shape how young people manage and negotiate their self-identities; 2) How and in what ways the maintenance of a visually ‘mediated presence’ in social media shapes young people’s construction and presentation of self; 3) The visibilities that digital devices and social media allow, encourage, or constrain and how young people understand and negotiate these. The empirical aspects of the research draw upon in-depth interviews (n=35) and social media platform analyses with the same participants, focusing on emerging ‘practices of looking’ as well as the content of images. Findings provide insight into how routine practices of looking that are facilitated by smartphones and social media are adding a significant new component to how young people experience everyday life, particularly in terms of precise social expectations and conventions around managing the ‘new visibilities’ of mediated life.

abstract: PhD


title: Model-Based Optimal Design of Experiments with Noninvertible Fisher Information Matrix

contributor:
McAuley, Kimberley
Chemical Engineering

subject:
Model-Based Design of Experiments
Mathematical Modeling
Fisher Information Matrix
Bayesian Design of Experiment
Parameter Subset Selection
Leave Out Method

abstract: In this thesis, different approaches are developed and compared to deal with a noninvertible Fisher Information Matrix (FIM) when designing sequential model-based (e.g., A, D, and V-optimal) experiments. Proposed approaches for dealing with this problem include: i) a “leave out” approach where problematic parameters are identified and left out of the design problem (LO approach), ii) a pseudo-inverse approach where the Moore Penrose pseudo inverse is used (PI approach), iii) an approach where modelers select new experiments based on their prior knowledge without using a formal experimental design technique (MS approach), a simple Bayesian approach that adds prior parameter knowledge to the FIM when designing experiments and therefore making it inventible. This study focuses on sequential A- and V-optimal design because these optimality criteria are relatively easy for modelers to interpret and are the most readily usable design criteria for situations where the FIM is noninvertible. Different case studies are investigated including two case studies involving production of pharmaceutical agents. The results for comparing LO, PI and MS approaches indicated that LO is the superior approach on average compared to two other approaches for both A- and V-optimal experiments. In addition, results indicated that, designing experiments using either LO or PI approaches are better than picking the corners of the design space as new experimental conditions, even for situations where the FIM is noninvertible. Next, a simple Bayesian approach is developed that adds the prior parameter knowledge to the FIM and makes in invertible for sequential MBDoE. Comparing the results of the Bayesian and LO approaches indicated that, the Bayesian approach is superior than the LO approach for MBDoE and the LO is better on average for parameter estimations.

abstract: PhD


title: Modulation of neurogenesis and apoptosis in the adult enteric nervous system

contributor:
Lomax, Alan
Neuroscience Studies

subject:
Adult neurogenesis
Enteric neurons
Apoptosis

abstract: Gastrointestinal (GI) disorders are often accompanied by a loss of enteric neurons, leading to GI dysfunction. Although a population of enteric neural stem cells (ENSCs) resides within the adult enteric nervous system (ENS), postnatal neurogenesis has been difficult to demonstrate in vivo. However, when enteric neurons are dissociated in culture, the brake on neurogenesis is released and ENSCs give rise to new neurons. Thus, the disruption of neuronal networks appears to release the proliferative brake on adult ENSCs. We hypothesized that neurotransmission is the factor that is disrupted by dissociation which may inhibit the proliferation of NSCs within the adult ENS, and that removal of this inhibition will give rise to neurogenesis. Longitudinal muscle and myenteric plexus (LMMP) preparations from adult mouse colon were organotypically cultured in vitro for one week while inhibiting various forms of neurotransmission. Immunohistochemistry for Human C/D (HuC/D) was used to identify myenteric neurons while the thymidine analogue, ethynyl deoxyuridine (EdU), was used as a marker of cell proliferation to detect neurogenesis. Inhibition of cholinergic, purinergic, serotonergic, and nitrergic neurotransmission increased enteric neurogenesis. Surprisingly, although neurogenesis increased, neuronal number remained constant. Inhibiting apoptosis in vitro using the pan-caspase inhibitor zVAD-fmk (80 µM) increased neuronal number within the myenteric plexus but had no effect on neurogenesis. Furthermore, inhibition of nitrergic neurotransmission using 7-nitroindazole (7-NI; 30 µM), in the presence of zVAD, led to an increase in neurogenesis and enteric neuronal number. However, when attempting to recreate our findings in vivo, inhibition of nitrergic neurotransmission, using 7-NI (30 mg/kg), had no effect on neurogenesis or neuronal density within the myenteric plexus. Together, our results indicate neurotransmission modulates the proliferative capacity of ENSCs, but caspase-dependent apoptosis regulates the neuronal population in vitro. By understanding the mechanisms underlying enteric neurogenesis, a viable therapeutic avenue to restore enteric innervation following GI injury may be identified.

abstract: M.Sc.


title: Plasticity of Vagal Afferent Neurons During Gut Microbial Dysbiosis and Inflammation

contributor:
Lomax, Alan E.
Neuroscience Studies

subject:
Plasticity
Vagal afferent neurons
Inflammation
Gut microbiota
Protease
Excitability

abstract:
Increasing evidence has suggested that vagal afferent neurons can mediate gut microbiota induced effects in the brain and immune modulation during gut inflammation. However, the mechanisms behind the alteration in the activity of vagal afferent neurons by gut bacteria and during inflammation are yet to be fully characterized. The present thesis tests the hypothesis that the gut microbiota and inflammation modulate the excitability of the vagal afferent neurons.
 	Perforated and whole-cell patch-clamp recordings were performed on dissociated nodose ganglia (NG) neurons to measure rheobase and to study the properties of voltage-gated ion channels respectively. I examined the effect of intestinal microbiota on mouse vagal afferent neurons in two ways: 1) incubating dissociated neurons in vitro in supernatant from a community of commensal gastrointestinal bacteria derived from a healthy human donor (Microbial Ecosystem Therapeutics; MET-1); and 2) by inducing microbial dysbiosis in vivo by oral administration of a non-absorbable antibiotic (vancomycin 50 ng/ml). Both exposures to MET-1 supernatant (1:100) in vitro and vancomycin-induced microbial dysbiosis increased the excitability of NG neurons, decreasing the mean rheobase by over 25%. The increase in excitability was reversed using a cysteine protease inhibitor (E-64, 30 nM) and a protease-activated receptor 2 antagonist (PAR2) (GB-83, 10 µM). Furthermore, voltage-clamp recordings revealed that incubation of NG neurons with MET-1 and antibiotic treatment hyperpolarized the voltage dependence of half-activation of Na+ conductance. Together, these findings suggest that cysteine proteases, in vitro and in vivo, increase the excitability of vagal afferent neurons by the activation of PAR2.
To determine the effect of inflammation on vagal afferent neurons, the excitability of dissociated NG neurons from mice with DSS-induced colitis was measured. DSS treatment increased the excitability of NG neurons by decreasing the rheobase by almost 30%. The serum from DSS treated mice recapitulated the effect of DSS administration on NG neurons, which was blocked by a nuclear factor-κB (NF-κB) antagonist suggesting that circulating mediators that activated NF- κB signaling pathway increased the excitability of NG neurons. Taken together, these studies suggest modulation in activity of vagus nerve can influence the effect of gut microbiota and inflammation on brain.

abstract: PhD


title: Transparent Omniphobic Coatings that are Flexible and Wear Resistant

contributor:
Liu, Guojun
Chemistry

subject:
Omniphobicity
Coating
Wear Resistance
Flexible

abstract:
Omniphobic or anti-smudge surfaces require good mechanical durability to ensure that they are suitable for practical applications.  In general, the abrasion resistance of a surface depends on its hardness.  However, when a coating is very hard, it is usually brittle and lacks flexibility.  New coating materials that impart high degrees of hardness and flexibility without sacrificing the excellent anti-wetting properties and optical transparency would have many potential applications.  However, the fabrication remained an elusive goal.
       Reported herein is a molecular composite that combines these desirable properties.  The composite is prepared via the photo-initiated cationic ring-opening polymerization of the epoxide rings of glycidyloxypropyl polyhedral oligomeric silsesquioxane (GPOSS).  While the desired hardness is rendered by the silica core of GPOSS, the flexibility is imparted by the glycidyloxypropyl network.  In addition, oil and water repellency is achieved without adversely affecting the other properties by incorporating into the coating a low-surface-tension liquid lubricant polydimethylsiloxane.  Various organic solvents and water readily and cleanly glide off the final coating, while complex fluids such as ink and paint facilely contract on this surface.  These properties are retained after an initially flat coating sample is rolled into a U-shape 500 times or is abraded with steel wool.  While the reported coatings have various applications, the insight gained from the research will also facilitate the design of other analogous materials.
        This thesis also reports the preparation of such a flexible hard omniphobic coating via the thermal curing of another formulation.  The formulation consists of blends of poly(ethylene-alt-maleic anhydride)-graft-polydimethylsiloxane (PEMA-g-PDMS) and cycloaliphatic epoxy-functionalized oligosiloxanes (CEOS).  The anti-wetting agent of polydimethylsiloxane (PDMS) was covalently attached to poly(ethylene-alt-maleic anhydride) (PEMA) via the reaction between the terminal amine group of PDMS and maleic anhydride group of PEMA.  The resultant grafted polymer was further heat-cured with the chemically blending of cycloaliphatic epoxy-functionalized oligosiloxanes (CEOS).  Only 2.8 wt% of polydimethylsiloxane (PDMS) existing in the coating matrix can impart the anti-smudge properties.  Test liquids with various surface tension such as water, hexadecane, dodecane can easily slide off the omniphobic surface without leaving a residue.  Moreover, the improvement of the coating matrix hardness can significantly increase its omniphobic durability.  This coating is also transparent, foldable and has good adhesion to a flexible poly(ethylene terephthalate) (PET) substrate.

abstract: PhD


title: Exploring Narratives of Quality Participation Among Adults with Physical Disabilities in a Community-based Exercise Program: A Mixed Methods, Collective Case Study Approach

contributor:
Tomasone, Jennifer
Kinesiology and Health Studies

subject:
Quality
Participation
Physical Disability
Exercise
Community-based
Narrative

abstract: Previous explorations of quality participation in physical activity opportunities for persons with disabilities (PWD) have yet to address whether one’s perception of quality participation can change over time. Using triangulation within a mixed methods approach, this study sought to explore the participatory experiences of PWD in a community-based exercise program. Over one year, five individuals completed a baseline interview grounded in a life course approach, and subsequent interviews at 4-, 8-, and 12-months. Participants also completed questionnaires at baseline, 4-, 8-, and 12-months to quantitatively elicit their perceptions of quality participation. Situated within social constructionism, (a) dialogical and structural narrative analysis of interviews were conducted; (b) the mean scores from the quantitative measures were ‘qualitized’, and (c) holistic profiling took place to explore similarities and differences between the two types of data, on a case-by-case basis. Five distinct narrative types represented the progression of quality participation over time, with each case drawing upon existing discourse and socioultural narratives of disability (i.e., tragedy and dependence), and participation in society (i.e., quest, restitution). The findings illustrate the immediate and latent psychosocial, emotional, and physical complexities that accompany participation in a community-based exercise program for PWD. These unique, temporally-nuanced understandings of quality participation offer insight into the highly contextualized nature of how PWD might achieve full and effective participation, and may be used to inform the development and delivery of optimal community-based exercise programming.

abstract: M.Sc.


title: Optimal payoff to ensure opacity in Discrete-Event Systems

contributor:
Rudie, Karen
Electrical and Computer Engineering

subject:
Discrete-Event Systems
Opacity
Dynamic Programming
Enforcement
Longest Common Subsequence problem

abstract: Opacity is a property of systems which guarantees that an outside observer cannot distinguish some behaviour of the system (secrets) from other behaviours (non-secrets). Many companies and government agencies like to make some aspects of their processes opaque to any observer while still needing to reveal some information. To enforce opacity, discrete-event systems have been employed and many algorithms are proposed. One naive way of achieving opacity is to hide everything. However, in many applications this is not possible either due to legal obligations or due to the requirement of sharing as much information as possible with other companies or with the public. Some algorithms have been developed that reveal as much information as possible while keeping a system opaque. However, these algorithms are very computationally complex and they treat all the revealed transitions equally (which might not be a reasonable assumption in real-world applications). Thus, to solve the complexity problem we propose using a dynamic programming approach, which relies on the solution to the longest common subsequence problem. This approach can lower the complexity of the solution at least for some cases (namely, systems with no loops). Secondly, we propose to add utilities for revealing transitions and provide algorithms that enforce weak opacity while guaranteeing a maximum payoff. The correctness of the algorithms are proven and their computational complexities are computed.

abstract: M.A.Sc.


title: The Internationalization of Education and its Effects on the Self-Efficacy of Rural Secondary Mathematics Teachers in Supporting English Language Learners

contributor:
Cheng, Liying
Education

subject:
English Language Learners
English as a Second Language
Secondary Education
Rural Education
Mathematics
Mathematics Education
Teacher Voice
Mathematics Curriculum
Rural Ontario
Education
International Education
Self-Efficacy

abstract: The internationalization of education is happening in secondary schools across Canada. Between 2015 and 2017, the number of international students arriving in Canada increased by 41 percent. Ontario alone hosted over 121,000 international students in 2017, and the numbers are projected to go up. Research has shown that both rural and urban school boards are actively recruiting international students. This phenomenon is resulting in increased numbers of English Language Learners (ELLs) in mainstream secondary classrooms. The study examined the effects of this internationalization from the perspective of the lived experience of a small sample of rural secondary mathematics teachers. Unlike those teaching in urban city centres who are likely to have more experience working with ELLs due to historical immigration patterns in Canada, those teaching in rural areas may not be as prepared to work with the linguistic, social, and cultural demands that come with working with ELLs. This qualitative study used open-ended, semi-structured interviews with five rural secondary mathematics teachers and examined the personal and professional challenges faced by these teachers working in a domain-specific class that also requires a knowledge of a specialized language to understand the content. Three themes emerged from the data: (a) Contextual Situation of the School Environment, (b) Teacher Perceptions of International Students, and (c) Teaching Practice. The study makes a significant contribution to the limited research surrounding rural secondary mathematics teachers working with international students in a Canadian context and a discovery of a large gap in research-based strategies and resources for these teachers, specifically those provided by the Ministry of Education of Ontario. The study highlights the need for improved teacher education, for both pre-service and in-service teachers, to increase awareness and understanding of culturally responsive pedagogy and the teaching of language in content classrooms.

abstract: M.Ed.