title: Tectonometamorphic Evolution of the Karnali and Jajarkot External Crystalline Klippen, Western Nepal Himalaya

contributor: Geological Sciences and Geological Engineering

subject:
Himalayan Tectonics
Himalayan External Crystalline Klippen
South Tibetan Detachment
Greater Himalayan Sequence
Microstructure
Phase Equilibria Modeling
U-Th/Pb Petrochronology
40Ar/39Ar Geochronology

abstract: Field mapping and microstructural characterization of metamorphic rocks exposed in the Karnali and Jajarkot klippen in the western Nepal foreland highlight the presence of a top-to-the-southwest shear zone at the base and a top-to-the-northwest shear zone at the top of the metamorphic rocks, correlative with the Main Central thrust and the South Tibetan detachment, respectively. This structural geometry implies that these metamorphic rocks are the southern continuation of the Greater Himalayan sequence (GHS) exposed in the hinterland to the north, and are key locations to improve our understanding of mid-crustal evolution in continental collisions. New pressure–temperature–time–deformation data demonstrate that GHS rocks in the Karnali and Jajarkot klippen escaped the Miocene high-temperature metamorphic overprint pervasive in the hinterland, and consequently reveal the Eocene-Oligocene stages of the evolution of the metamorphic core. In the Karnali klippe, prograde metamorphism occurred between 40 and 35 Ma and P–T conditions peaked at >0.7–1.0 GPa and >650–700 °C between 35 and 30 Ma. Starting at 30 Ma, GHS rocks underwent cooling, decompression and melt crystallization associated with the onset of shearing along the top-to-the-NE normal-sense South Tibetan detachment. The GHS cooled below ~450 °C progressively from the south flank (20–17 Ma) to the north flank (17–14 Ma) of the Karnali klippe. In the Jajarkot klippe, prograde metamorphism occurred from 45 to 25 Ma, when peak P–T conditions of 0.75–1.2 GPa and 550–600 °C were attained. Peak metamorphism was followed rapidly by cooling below ~450 °C at 25–20 Ma. In marked contrast, GHS rocks now exposed in the hinterland were still buried, hot, and actively deforming while the foreland was cooled and exhumed. The klippen therefore preserve a snapshot of the early (i.e. Eocene-Oligocene) evolution of the Himalayan metamorphic core. Along-strike variations in the tectonometamorphic evolution of the two klippen are interpreted to reflect the geometry of the basal detachment of the orogen and suggest the presence of an east-dipping lateral ramp between the Karnali and Jajarkot klippen during the Oligocene.

abstract: PhD


title: A Dream Denied: The Fight Against the Mass Eviction of Families in Chicago and Jacksonville, USA

contributor:
Kobayashi, Audrey
Geography and Planning

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:
Housing
Homeownership
Race
Neoliberalism
Racial Capitalism
Financial Literacy
Financialization
Institutional  Racism

abstract:
The foreclosure crisis that followed the depression 2007–08 created a number distressed communities in two of the hardest hit cities across the United States, Chicago, and Jacksonville. Homeownership has long been the primary means for households to accumulate wealth within American society. Owning a home also assumes tremendous cultural weight; is often associated with achieving the American dream. Becoming a homeowner is said to allow first-time buyers to embrace the values of freedom and individualism; however, since 2007, a disproportionate number of racialized people have been evicted from their homes at an unprecedented rate because they were unable to continue making payments on their mortgages. Subprime loans were introduced to the lending market as a lucrative business strategy to expand lending activities to those who would otherwise be denied access to credit. Instead, they allowed financial institutions to exploit and prey upon the historical misfortunes of African Americans and other racialized groups. This study uncovers some key findings that indicate how organizations working in different geographical regions navigate through the foreclosure crisis in order to keep at-risk homeowners inside their homes. Furthermore, this study highlights the importance of community organizations and their influence in shaping the foreclosures for racialized people, low-income families, and economically disadvantaged communities.
In keeping with the traditions of anti-racist theory, I situate race at the forefront of my analysis of the policies and programs introduced to stem the rise of foreclosures. By doing so, I develop an analysis of the cyclical nature of institutional racism as it operates in the U.S. housing market. More importantly, I situate the foreclosure crisis as the most recent installment in the long history of racial inequality in the American housing market. I draw on theoretical perspectives on neoliberalism and financialization to identify the products and processes that precipitated the collapse of the U.S. housing market.
I use secondary data and a small sample of semi-structured interviews with homeowners, housing counselors, and lawyers, and the research reveals a number of factors influencing the way some African-American households experience foreclosures. The research also pinpoints some of the best ways to keep distressed homeowners inside their homes. Above all, this study provides racialized homeowners with a voice, dispelling popular narratives that portray them as irresponsible borrowers who bought more than they could afford. Instead, everyday Americans were victims of a discriminatory financial system that preyed upon the historical disadvantages of African Americans in their efforts to attain equal access to the housing market.

abstract: PhD


title: Unpacking Reading Comprehension by Text Type: An Examination of Reading Strategy Use and Cognitive Functioning in Poor and Typically-Achieving Comprehenders

contributor:
Berg, Derek
Education

subject:
Reading Comprehension
Cognitive Functioning
Executive Functioning
Working Memory
Reading Strategies
Learning Disabilities

abstract:
In the present study, I examined how students build comprehension with different types of text. Poor comprehenders and typically-achieving comprehenders, as determined by a standardized measure for general reading comprehension, were compared in their reading comprehension and reading strategy use across narrative, expository, and graphic text. I also examined the influence of cognitive functioning on reading comprehension, and to what extent cognitive functions can explain the difference in reading comprehension between poor and typically-achieving comprehenders. This research was partially exploratory, where I aimed to validate existing research on cognitive functions, reading strategies, and reading comprehension of text, as well as to contribute new research that distinguishes between text types. Past research has shown that cognitive functions predict reading comprehension and that poor comprehenders have poorer cognitive functioning and use fewer reading strategies than their peers. However, no research to date has made distinctions between different types of text, specifically graphic text, and how cognitive functioning and reading strategy use relate to comprehension.
A group of poor comprehenders (n = 24) and typically-achieving comprehenders (n = 38) completed measures of cognitive functioning and read narrative, expository, and graphic texts aloud before answering comprehension questions. Participants were asked to ‘think-aloud’ during reading, which allowed me to make comparisons between the two groups on reading strategy use. Poor comprehenders used fewer cognitive strategies than their typically-achieving peers while reading narrative and expository text, and fewer evaluative strategies with graphic text. Typically-achieving comprehenders also outperformed poor comprehenders on comprehension of each style of text. Participants’ abilities to recognize abstract patterns predicted comprehension of each text type, while participants’ abilities to exercise inhibition also predicted expository text comprehension. The same variables accounted for a significant portion of the variance between poor and typically-achieving comprehenders, though graphic text had the most variance unaccounted for. The findings from the present study highlight the importance of distinguishing between text types in research on reading comprehension, and suggest that more attention should be paid to dynamic reading comprehension instruction and support.

abstract: PhD


title: The Characterization of a Weakly Basic Chemisorbent Polyacrylamide Hydrogel for its Applicability to Downstream Succinic Acid Recovery

contributor:
Daugulis, Andrew
Chemical Engineering

subject:
Bioproduction
Succinic acid
Absorbent
Adsorbent
Chemisorbent
ISPR
Polymer
Downstream Recovery

abstract: Commercial bioproduction of succinic acid has been stimulated by its use as a precursor in the synthesis of commodity chemicals, and the benefits of bioproduction compared to traditional chemical synthesis. However, inefficiencies remain in the downstream recovery of succinic acid from fermentation medium. The use of chemically reactive sorbents (chemisorbent) can streamline downstream succinic acid recovery, reducing costs. In this study, Poly[N,N-dimethyletheyleneacrylamide-co-Tris(2-aminoethylacrylamide)] (PMTA) was synthesized and characterized for the downstream recovery of succinic acid. PMTA sorbs succinic acid through acid-base reactions, sequestering it as an ammonium succinate salt. At a 0.02 dry weight (DW) phase fraction (PF) PMTA chemisorbed 0.45 g of succinic acid from a 35 g/l solution, the highest capacity known. PMTA was found to be stable in aqueous solution after 10 days, an improvement over polyacrylate type chemisorbents. Complete desorption of succinic acid from 1g DW polymer was achieved with 50 ml of a 3 M KOH solution, at a 0.02 PF. Despite this elevated concentration of KOH, the polymer retained its sorption capacity after 3 cycles of sorption and desorption. PMTA was found to chemisorb all three acids found in succinic acid fermentations, including formic, acetic and succinic acid, preferentially sorbing the most concentrated acid. However, at equal molar concentrations of these acids, formic acid, having the lowest pKa, was preferentially sorbed. PMTA has properties applicable to the downstream recovery of succinic acid including resistance to hydrolysis, reusability, and high succinic acid sorption capacity. PMTA was applied as an alkaline extractant in an in situ product removal (ISPR) system. To simulate bioproduction, succinic acid was fed into a bioreactor; the drop in pH activated a pump directing bioreactor contents through a vessel containing water alkalized by the presence of PMTA, and this water was displaced into the bioreactor increasing the pH. The pH was further modulated by the sorption and sequestration of succinic acid from the bioreactor contents pumped through the ISPR system. However, it was found that the alkalinity of the tertiary amine functional group of PMTA was insufficient to maintain the bioreactor pH at the set point.

abstract: M.A.Sc.


title: A Framework with Improved Spatial Optimization Algorithms to Support China’s “Multiple-plan Integration” Planning at the County Level

contributor:
Chen, DongMei
Geography and Planning

rights: Attribution-NonCommercial-NoDerivs 3.0 United States

subject:
Spatial Optimization
"Multiple-Plan Integration"
China

abstract:
The “Multiple-plan integration” planning is proposed by the Chinese government to coordinate various planning projects in managing spatial development and protecting agricultural and ecological resources. It can be treated as a multi-objective land allocation (MOLA) problem that aims to optimize the land allocation pattern to maximize land suitability for agriculture, construction, and conservation while encouraging compact land allocation. However, there is a lack of applicable methodology or frameworks to support the “Multiple-plan integration” planning at the county level.
This dissertation is intended to develop and test a framework to solve this “Multiple-plan integration” problem with improved spatial optimization algorithms. The criteria for land suitability evaluation in China’s county-level “Multiple-plan integration” were first reviewed and established. Then, the performance of three classical heuristic optimization algorithms including simulated annealing (SA), genetic algorithm (GA), and particle swarm optimization (PSO) was compared in solving a simplified MOLA problem. The comparison results show that classical NSGA-II in the GA family performs the best, but its computational cost is high in maintaining compact land allocation. Next, an improved knowledge-informed NSGA-II was developed by integrating patch-based, edge growing/decreasing, neighborhood, and constraint steering rules. The improved algorithm is more effective and efficient than classical NSGA-II in encouraging compact land allocation while its capability of maximizing land suitability is not sacrificed. Finally, a Multiple-plan Integration with Spatial Optimization (MPI-SOP) framework was proposed to support China’s “Multiple-plan integration” planning at the county level. This framework is composed of five steps: mathematically formulating the spatial optimization problem, land suitability evaluation, optimization problem solving, post-processing of land allocation solutions, and applying post-processed solutions to planning. The spatial optimization problem was solved by a patch-based and knowledge-informed NSGA-II. The case study in Dongxihu District of Wuhan City shows that the framework is feasible and effective in supporting the “Multiple-plan integration” decision making.
This dissertation has made two major contributions. Practically, it has proposed and tested a framework to support China’s “Multiple-plan integration” planning with spatial optimization at the county level; methodologically, knowledge-informed heuristic optimization algorithms have been developed to solve the MOLA problem more effectively and efficiently.

abstract: PhD


title: Securing Web Applications with Secure Coding Practices and Integrity Verification

contributor:
Zulkernine, Mohammad
Computing

subject:
Web Application Security
Javascript
Integrity Verification

abstract: The concept of security in web applications is not new. However, it is often ignored in the development stages of the web applications. Being multitiered and spread across different domains, it is challenging to come up with a security solution that works for all web applications. Moreover, developers are more inclined to produce working features for the applications in the rapid development approaches that are chosen, than providing security for the code and often do not practice secure coding. Therefore, countless web applications are launched with security vulnerabilities which manifest later in their life cycle. Integrating security features should be part of the development process for these web applications to prevent unwanted attacks. Along with cross-site scripting, injection attacks and resource alterations; code tampering on the client side is a serious security risk for web applications. Without practicing secure coding and having an integrity verification system in place, it is difficult to defend these unwanted attacks. We present a system that integrates security measures on the client side code based on the best practices of secure coding and an integrity verification system. The proposed approach can be integrated with both new and existing web applications to provide security against prevalent attacks and make the client side tamper resistant. We implement our approach for JavaScript-based applications for which the security flaws are the most common.

abstract: M.Sc.


title: An Empirical Study of Android API Use in Google and Non-Google Applications

contributor:
Cordy, James R.
Computing

subject:
Android
Android API
Android Applications
Google
API Analysis
API Use

abstract:
Android is the most popular mobile platform powering hundreds of millions of mobile devices. Android provides an API that helps developers create Android applications by simplifying the reuse of core system components and services. Different developers may use the Android API in different ways for several reasons, including: their background, their knowledge of the platform and their team's policies. This variety in how developers interact with the Android API, makes Android API use analysis an interesting research topic.
Android is owned and maintained by Google. In each release of the Android API, Google introduces new capabilities and deprecates some of the old ones. In this thesis, we investigate the fact that, since Google is itself both maintaining and using the API at the same time, it may be using Android differently than other developers.
In order to explore our research questions, since existing methods could not address some of the challenges in our study, we proposed a new method for analyzing Android API use in closed source Android applications. This method works on obfuscated applications and radically reduces the noise produced by embedded API calls in the unused parts of third-party libraries.
Using the proposed method, we conducted an experiment for comparing Android API use in 19 popular Google applications to 19 non-Google similar applications and answered four specific research questions that show the differences between these two groups of applications.
The analysis in this thesis can be helpful for Android developers to find out how Google, as the owner and maintainer of Android, is using the Android API. Additionally, Google can use this information to observe how the changes they make affect the developers' interaction with the Android API.

abstract: M.Sc.


title: Mandatory Career Change: Transition Experiences of Canadian Armed Forces Veterans

contributor:
Stockley, Denise
Education

subject:
Canadian Armed Forces
Veteran
Transition
Medical Release
Decision-Making Process

abstract:
For all serving military personnel, transition to civilian life is inevitable; however, a release may come as a surprise for the approximately 2000 service members who retire annually as a result of a medical condition (Department of National Defence, personal communication, 28 June, 2017).  These Veterans will leave the Canadian Armed Forces (CAF) under vastly different circumstances than those who voluntarily release.  A medical release can be a result of a visible or non-visible wound suffered in an operational theater, a training injury or a chronic disease diagnosis.  In a follow-up to landmark cross-sectional survey, Veterans Affairs Canada (2017a) concluded that 32% of releasing Veterans experience a difficult transition to civilian life; which, indicates the need for tailored transition services and research into the causes of these struggles.  The trinity of an unexpected truncation of one’s career, a medical diagnosis coupled with an uncertain health status, and a precarious future signal the start of a soldier-to-civilian transition that many Veterans are ill-prepared to confront.
Service members finding themselves on this trajectory are faced with a myriad of decisions that impact the totality of their lives.  Aspects of military life are not limited to a predictable daily regime, rather service extends beyond the uniform affecting family and friends; a truly a unique way of life.  One condition of military employment is that soldiers and families must move to various Canadian Forces Bases located in both major metropolitan areas with the associated high cost of living to rural locations with limited prospects for spousal employment, school choices for children, reduction of some community services offered in either French or English, or readily available access to family health care.  When soldiers are leaving the CAF for civilian life, some of these considerations must be addressed to contribute to a successful transition.  This study investigated the individual decision-making process surrounding a mandatory career change with a view to better inform policy-makers and transitioning Veterans.  Findings indicate that a more deliberate institutional approach to transition will empower Veterans to realize their post-military potential with the assistance of a tailorable transition decision-making aid.

abstract: M.Ed.


title: Thriving in Higher Education: Voices of Four Female Graduate Students

contributor:
Christou, Theodore
Education

subject:
Graduate students
Graduate school
Positive mental health and well-being
Thriving

abstract:
This study explored thriving in the context of graduate studies as perceived by four female students attending master’s and doctoral programs in a Canadian university. Thriving is an all-encompassing approach that extends beyond meeting the academic objectives (Schreiner, Pothoven, Nelson, & McIntosh, 2009). Recently, there have been extensive studies regarding thriving in the undergraduate context (e.g. Berea, Tsvetovat, Daun-Barnett, Greenwald, & Cox 2015; Schreiner, 2010a; 2013; Schreiner, Kammer, Primose, & Quick, 2011). Despite the uniqueness of the graduate demographic compared to the undergraduate (Gansemer-Topf, Ross & Johnson, 2006), little is known about graduate students’ thriving processes and their fulfillment with their academic experience. The purpose of this qualitative study was to understand graduate students’ perceptions and experiences of thriving, as well as the factors that influenced their thriving in graduate school. Data were collected from four female graduate students through semi-structured interviews and analyzed using a deductive thematic approach. Thriving Perceptions and Experiences, Supports for Thriving, and Barriers to Thriving were the pre-determined themes utilized for this study. Supports and barriers were further branched into intrapersonal, interpersonal, and institutional factors.
The findings of this study are presented in two sections. The first section highlighted thriving conceptualization in graduate studies through individuals’ perceptions and experiences. These findings illustrate that thriving in graduate studies is unique, multi-faceted, and malleable. For master’s participants in particular, thriving additionally signified a profound academic transition. In the second section, I presented the conditions that affected thriving, which included notions of connectedness, contribution, mentorship, compartmentalization, and imposter syndrome. Although similar to undergraduate students in many ways, there were distinct characteristics pertaining to thriving among the participants of this study, leading to implications for future research and practice.
Keywords: graduate students, graduate school, positive mental health and well-being, thriving

abstract: M.Ed.


title: Intense Navigation: Using Active Sensor Intensity Observations To Improve Localization and Mapping

contributor:
Marshall, Joshua
Electrical and Computer Engineering

subject:
Robotics
Time-of-Flight
Localization
Mapping
Visual Odometry
SLAM
LiDAR
Navigation

abstract:
Where am I? This question continues to be one of the fundamental challenges posed in robotics research. The ability of a robot to localize itself and map its environment has proven to be a difficult and rich research problem. While significant progress has been made it still remains a difficult task to perform in dynamic, 3D environments, over long distances. Stereo cameras are a proven workhorse for the task of Visual Odometry (VO) and three-dimensional Simultaneous Localization and Mapping (SLAM), but they require reliable lighting conditions and matching regions in both images. Light Detection And Ranging (LiDAR) sensors provide an alternative; they are lighting-invariant, provide dense depth information directly, and intensity information that resembles grayscale camera images. In many cases where lighting is unavailable or inconsistent, such as underground mining or planetary exploration, LiDAR is particularly suited for the task of localization.

Both VO and SLAM can use a type of nonlinear optimization called bundle adjustment (BA) to solve for the optimal sensor pose and landmark positions given a set of matched observations at two or more separate poses. This thesis develops a version of BA, called IntenseBA. The algorithm estimates a map of landmarks, augmenting the standard three-dimensional point landmark with surface normal and reflectivity states. Because LiDAR intensity observations are dependent on the sensor pose and these landmark states, it is able to use observations of the landmarks to probabilistically determine the most likely estimate of the sensor pose and landmarks. The problem is shown to be observable in all states and an analysis of its sensitivity to noise in each observation is done through a simulation. A calibration procedure and analysis of modern keypoint algorithms is presented which allows the theoretical model to be applied to real data from a SwissRanger SR4000 Time-of-Flight (ToF) camera. Experiments were conducted in the European Space Agency's Planetary Utilisation Testbed, which emulates a Martian terrain. These experiments tested the IntenseBA algorithm (used to perform VO) and show the algorithm can accurately map all state estimates and improve upon accuracy compared to traditional and state-of-the-art approaches by incorporating these additional observations.

abstract: PhD


title: Quality Assurance Testing, and Sensitivity Studies for the SNO+ Experment

contributor: Physics, Engineering Physics and Astronomy

subject:
SNO+
Neutrino
Neutrinoless Double Beta Decay

abstract:
For the SNO+ experiment's search for neutrinoless double beta decay, radioactive background reduction and understanding of detector systematics are key. Indirect background measurements and energy systematics have been studied. A quality assurance testing system was created and implemented. The system detects the oxygen contamination of liquid scintillator as an indirect measurement of radon-222 contamination from air exposure during transport. The technique can measure ppm order oxygen contamination with a resolution of ~60ppm. In addition, the impact of non-
gaussian tails in the energy response function on the half-life limit for neutrinoless beta decay was studied. If the tails were not applied to the energy response function the sensitivity is expected to be reduced by 0.5x10^26y. If the tails are applied to the response function, the half-life limit would be approximately 1.7x10^26y after one live year of data. For tellurium to be loaded in the detector, an organometallic complex is formed. The impact of the complex on acrylic was studied with the engineer of record approving the use of tellurium loaded scintillator for ten years with minimal
deterioration expected.

abstract: M.Sc.


title: Investigation of Fractures as a Background in Rare-Event Searches

subject:
Fractures
Dark Matter
Rare-Event Searches
Backgrounds

abstract:
Rare-event searches in particle physics put immense effort into precisely controlling their backgrounds.
However, not always considered is the effect of fractoluminescence if the active material
fractures. The effect of atmosphere on the fractoluminescence of the scintillator BGO (Bi4Ge3O12)
has been studied by stressing samples in a double-cleavage drilled compression (DCDC) geometry
to fracture. A system has been developed to fracture samples in a controllable atmosphere and analyze
the light and acoustic emissions. By analyzing the fracture of BGO, it has been demonstrated
that the force required and the energy dissipated in fracture are increased as the water vapour in
the atmosphere is reduced. It has also been demonstrated that the quantity of emitted photons
increases in nitrogen rich atmospheres. These results demonstrate the importance of controlling
both the atmosphere and stresses inside particle detectors. In addition, in order to study the effect
of cryogenic temperature on fractures in particle detectors, a microfabricated polysilicon fracture
apparatus has been designed and subjected to first tests.

abstract: M.A.Sc.


title: Netherlandish Painting in Portugal: Trade, Reception, and Impact Around 1500

contributor:
Spronk, Ron
Art History

subject:
Art History
Portugal
Low Countries
Early Modern Painting
Technical Art History
Art Market

abstract: My doctoral work examines the reception, imitation, appropriation, and transformation of Netherlandish painting in Portugal around the turn of the sixteenth century through a study of surviving documents, visual evidence, and available (technical) studies. In chapter two, I discuss the limitations of the existing literature concerned with the painting production in Portugal in the fifteenth and sixteenth centuries, caused by its political seclusion from the nineteenth century until the 1970s. Diplomacy, trade, and immigration were the most important points of contact with Netherlandish painting in the fifteenth and sixteenth centuries and are the focus of chapter three and four. Chapter three reveals how Netherlandish luxury goods became part of Portuguese collections, while chapter four focuses on Lisbon artists that were a part of the network of court painter Jorge Afonso (c. 1470–1540). These artists were responsible for the production of some of the most prestigious royal altarpiece commissions of the first decades of the sixteenth century. Chapter five centres around the Évora Altarpiece, a nineteen-panel Netherlandish altarpiece produced around 1500. Here, I tentatively argue that the altarpiece was commissioned from Gerard David and then shipped to Portugal. David might have subcontracted several painters to complete the commission. In chapter six, I discuss three paintings that hung in two Colettine convents and depict the same unique iconography, an angel appearing before three kneeling Clarisse saints. Two paintings stylistically relate to Quinten Metsys, while the other was part of an altarpiece and is attributed to Jorge Afonso. The paintings were probably commissioned by Queen Eleanor who founded the convents and instigated the Colettine reform movement in Portugal. She might have been inspired by her contacts in Burgundy, perhaps Margaret of Austria, who was an active promoter of Colette’s reform. The paintings discussed in this dissertation exemplify how the import of Netherlandish paintings, the arrival of Netherlandish painters, and the favourable artistic climate in Portugal impacted the local production of altarpieces. Collaboratively produced by local master painters and their workshops, these heterogeneous altarpieces combine elements of Netherlandish (style, technique), Portuguese (cultural references, colour use), and Spanish (format) origin.

abstract: PhD


title: Factors Affecting Traction Coefficients During Intermittent Sliding Motion in Textured Metal-Polyethylene Bearings

contributor:
Bryant, Timothy
Bryant, Timothy
Mechanical and Materials Engineering

subject:
Total Joint Replacement
Polyethylene
UHMWPE
UHMWPE wear
UHMWPE friction

abstract:
In cases of severe arthritis, a metal-on-ultra-high molecular weight polyethylene (UHMWPE) total joint arthroplasty (TJA) is the primary solution. Wear of UHMWPE is a concern as it causes poor bearing performance and a decrease in the device’s lifespan. In this study, UHMWPE surface texturing has been proposed as a way to improve tribological conditions. Surface texturing has been studied previously under steady-state conditions, which is not representative of the harsh kinematic conditions occurring in daily living activities. Therefore, the objective of this study is to investigate the hypothesis that the proposed novel texturing approach improves tribological conditions during intermittent stop-dwell-start (SDS) motion by measuring the traction coefficient during the SDS phases.
	A custom waveform in a pin-on-disc friction and wear tester was created to simulate SDS loading conditions. Untextured and textured UHMWPE specimens were tested under three lubricating conditions (unlubricated, water and glycerin). Then, a method was developed to extract meaningful traction coefficient data from the SDS test results. Lastly, factors affecting the tribological conditions in the metal-UHMWPE system were investigated based on traction coefficient and wear analysis observations.
	The factors affecting the traction coefficient and wear were the introduction of texturing and the viscosity of the lubricant. The presence of a lubricant dominated when attempting to reduce the traction coefficient and wear. A significant reduction in traction coefficient was observed with both water and glycerin compared to unlubricated conditions in all phases of SDS motion, regardless of the surface geometry. Also, the higher the lubricant’s viscosity, the lower the traction coefficient and amount of wear.
	The introduction of the textured surface resulted in a significant reduction or no change in traction coefficient in the stop and start phases in the unlubricated and glycerin conditions. Also, no additional wear was observed when the surface was textured compared to untextured. Therefore, when the bearing system is properly lubricated, texturing is a promising approach to reduce traction and wear. It is therefore proposed that textured UHMWPE be further investigated as a solution to extend the lifespan on TJA.

abstract: M.A.Sc.


title: Unsettling Hegemonic Whiteness in Cultural Production: Praxis-based Approaches in Concert Dance

contributor:
Walker, Margaret
Cultural Studies

subject:
Cultural Production
Race
Nationalism
Canada
Multiculturalism
Blackness
Indigeneity
Whiteness
Dance
Citizenship

abstract: This dissertation examines the racialized power dynamics in cultural production in Canada by offering a re-reading of critical multicultural discourse through black and Indigenous studies. Although dominant modes of artistic creation circulate in and through colonial logics of domination, my research demonstrates the capacity for concert dance performance to destabilize the uneven power dynamics that shape such practice. Through a case-study approach, augmented by a self-reflexive research-creation component, I interrogate the ways in which current creative practices offer some trajectories for working towards more ethical and decolonial approaches to the creation of artistic work. What emerges is a scholarly analysis and critique of the ways in which hegemonic whiteness within concert dance in Canada persists, as well as a self-reflexive study that suggests some ways forward. I argue that concert dance is a productive and important site of scholarly critique and creative practice that, despite having been largely overlooked in the majority of academic study that attends to identity, power, and social justice, offers a way of re-thinking the decolonial potential of concert dance and dance performance.

abstract: PhD


title: Structural style and timing of deformation on the Bathurst fault in the eastern Slave craton, western Nunavut, Canada

subject: Bathurst fault

subject: Slave craton

subject: Thelon tectonic zone

subject: Thelon basin

subject: microstructural analysis

subject: U-Th-Pb geochronology

subject: 40Ar/39Ar thermochronology

subject: fault reactivation

subject: Precambrian geology

subject: basement fault zones

abstract: Crustal-scale basement faults persist as long-lived structures that localize deformation and can enhance permeability in the Earth’s crust. The NNW-striking left-lateral Bathurst fault in the eastern Slave craton displaces the 1.9 Ga Kilohigok basin and the ca. 2.07-1.96 Ga Thelon tectonic zone by up to ~ 115 km. The Bathurst fault intersects the 1.7 Ga Thelon basin, where unconformity uranium occurrences are spatially associated with basement faults. This thesis investigates the deformation-temperature-time history of the Bathurst fault rocks using field structural and microstructural observations paired with U-(Th-)Pb and 40Ar/39Ar geochronology. Highly-strained hornblende-bearing granitoid rocks with minor phyllosilicate-rich layers are predominant along the Bathurst fault and show ambiguous sense of shear suggesting flattening by coaxial deformation. Quartz and feldspar microstructures show ductile deformation conditions ≥ 500°C. Along the main fault trace, the pervasive ductile flattening fabric is overprinted by brittle fractures, cataclasis, and hydrothermal alteration. In situ U-Th-Pb dating of syn-kinematic monazite suggests ductile fabric formation at ca. 1933 ± 4 Ma and 1895 ± 11 Ma, whereas zircon from a cross-cutting dyke constrains the brittle deformation to ≤ 1839 ± 14 Ma. 40Ar/39Ar analyses of fabric-defining minerals yield cooling ages of ca. 1920-1900 Ma and ca. 1900-1850 Ma for hornblende and muscovite, respectively, and a maximum cooling age of ca. 1840 Ma for biotite. The ductile flattening fabric developed between ca. 1933-1895 Ma, and is associated with the orthogonal collision and indentation of the Slave craton into the Thelon tectonic zone and Rae craton. Brittle deformation on the Bathurst fault was localized parallel to the ductile flattening fabric after ca. 1840 Ma and preceded Thelon basin deposition. Brittle deformation features in Bathurst fault rocks demonstrate fluid-rock interaction and enhanced basement permeability. Thus, the Bathurst fault is a possible conduit basement structure for unconformity-associated uranium mineralization.

abstract: M.Sc.


title: Surgery, Anesthesia, and Risk for the Development of Dementia

contributor:
Seitz, Dallas
Stuart, Heather
Public Health Sciences

subject:
Epidemiology
Dementia
Alzheimer's disease
Anesthesia
Geriatrics
Surgery

abstract:
As Canadians continue to live longer, more older adults are undergoing surgical procedures. These procedures can leave patients at an increased risk for medical complications, and there has been growing interest in a potential association between surgery and dementia. When further examining this relationship, attention has been given to the potential role that anesthesia may have on risk for development of dementia. There are two main types of anesthesia administered for many surgeries, general (GA) and regional (RA). This thesis explored the association between surgery, anesthesia, and dementia by comparing for potential differences between GA and RA on the development of dementia following surgery.
	Using a retrospective cohort study design, older adults aged 66 years and greater who underwent elective surgical procedures were followed-up for up to 5 years following their index surgery. The surgical procedures that were included in this thesis were hip replacement, knee replacement, inguinal hernia repair, hysterectomy, and prostatectomy, since each are common procedures and can be completed using either GA or RA. Statistical analyses consisted of Kaplan-Meier survival curves and Cox proportional hazards models, where the hypothesis was that GA would lead to greater risk for the development of dementia following surgery compared to RA.
	To control for any potential differences in baseline characteristics that may bias the associations of interest and the outcome of dementia, matching was done on age, sex, index year, surgery, and propensity score. The final matched sample consisted of 14,998 individuals. A total of 725 people developed dementia throughout follow-up, 362 who received GA and 363 who received RA. After comparing people administered GA to those receiving RA, there was no significant difference in risk for development of dementia following surgery (HR = 1.0, 95% CI: 0.8 – 1.2, p = 0.9). Subgroup and sensitivity analyses supported these results, with no significant differences found between anesthesia groups.
	Therefore, this thesis found that there was no significant difference in dementia development following surgery when comparing people receiving GA and RA. Future studies should consider a randomized trial design and access more detailed data on the depth and duration of the anesthesia exposure.

abstract: M.Sc.


title: Comparative Study of the Effects of Physical and Chemical Aging on Extracted and Recovered Asphalt Binders  from Some Municipal and Provincial Roads in Canada

contributor:
Hesp, Simon A.M.
Chemistry

subject:
Physical Aging
Chemical Aging
Recycled Engine Oil Bottoms

abstract:
It has been reported that estimated pavement lifecycles have been reduced by 50-60 % in Ontario over the last 25 years (Auditor General of Ontario, 2016). This raises issues of concern with respect to durability and performance among others. This document aims to comparatively study the effects of physical and chemical aging on the performance of extracted and recovered loose-mix and core mix samples from some provincial and municipal contracts in Ontario.

In this study, four loose-mix (plant-aged) and eight core-mix (field-aged, 4 - 5 years) samples were cautiously extracted and recovered using dichloromethane and standard rotary evaporation in a moderate to high vacuum, nitrogen atmosphere and final bath temperature of 160 °C for one hour. The binders recovered from the loose-mix samples were taken through laboratory aging using the standard Superpave® pressure aging vessel method and all the samples were evaluated for their performance using conventional Superpave® methods such as Dynamic Shear Rheometer (DSR) and Bending Beam Rheometer (BBR) and the improved Ministry of Transportation of Ontario methods (LS-308 Extended Bending Beam Rheometer (eBBR) and LS-299 Double-Edge Notched Tension (DENT) test). Chemical test methods like Fourier Transform Infra-red (FTIR) spectroscopy and X-ray Fluorescence (XRF) analysis were used to determine the presence of carbonyls, sulfoxides, zinc and molybdenum which result from chemical oxidation and the addition of recycled engine oil bottoms (REOB).

The significant amount of zinc and molybdenum found in all the samples could be a result of addition of REOB, which is known to accelerate the process of physical and chemical aging. All the binders recovered from the loose-mix samples showed better performance based on their performance grading using the dynamic shear rheometer, extended bending beam rheometer and double-edge notched tension test at low, intermediate and high temperatures. Their durability is however suspect since they contained significant amounts of zinc, molybdenum, carbonyls and sulfoxides known to be ‘aging accelerators’. All the field-aged (4-5 yrs.) samples but one showed poor performance at low, intermediate and high temperature which is explained by the comparatively higher amount of zinc, molybdenum, carbonyls and sulfoxides found in them.

The extended bending beam rheometer (eBBR) method was seen as a more efficient quality control indicator since some of the samples which passed the regular bending beam rheometer method failed the extended bending beam rheometer test based on the grade losses.

abstract: M.Sc.


title: Rheological Evaluation of Field-Aged Asphalt Cements

contributor:
Hesp, Simon A. M.
Chemistry

subject: Asphalt Cement Specification

subject: Extended Bending Beam Rheometer (EBBR) Test

subject: Gel-Point Temperature

subject: Double-Edged-Notched Tension ( DENT) Test

subject: Critical Crack Tip Displacement (CTOD)

subject: Glover-Rowe Damage Analysis

subject: Thermal Cracking

subject: Fatigue Cracking

subject: Field-Aged Asphalt Cement

subject: Thermoreversible Aging

abstract:
The appearance of excessive and premature cracking on asphalt pavement after the winter
seasons has been a major challenge and concern to transportation agencies in Canada and
the northern U.S. states. At low temperatures, thermal stresses develop in the pavement
causing detachment of the binder from the aggregates and a subsequent deterioration in
stiffness which eventually leads to gross thermal cracking. Further distresses are induced
on these roads in the form of wheel path fatigue by heavy vehicles leading to alligatortype
cracks. Governments spend large portions of their yearly budgets on the maintenance
and reconstruction of damaged roads. Through the collaborative efforts of government
agencies and research institutions various laws and specifications have been implemented
to ensure durability of asphalt pavement across various provinces.
In this study, approved American Association of State and Highway Transportation
Officials (AASHTO) and Ministry Transportation of Ontario (MTO) methods namely
dynamic shear rheometer (DSR), extended bending beam rheometer (EBBR), and double
edge-notched tension (DENT) tests were used to evaluate the rheological properties and
long-term performance of recovered binders with 3 to 7 years of service. The recovered
samples showed similar properties as their corresponding tank samples even though there
exists a difference in their performance due to extent of aging which is only poorly
simulated by the rolling thin film oven (RTFO) aging and pressure aging vessel (PAV)
treatment of the tank samples. Easier, more automated test methods were attempted in this
study to replace or complement the EBBR and DENT. Gel point temperature and Glover-
Rowe analysis were conducted on all recovered samples. An r-squared value 0.72 was
obtained for the correlation between EBBR and gel point temperature while that between
iii
critical tip opening displacement (CTOD) from DENT test and the Glover-Rowe
parameter was 0.96. These results look promising and would require further studies to
come to more precise decisions. Chemical analysis using X-ray fluorescence (XRF) and
Fourier transform infrared (FTIR) were compared with rheological and physical tests, and
able to distinguish good performing binders from poor ones.

abstract: M.Sc.


title: The Horse-Drawn Omnibus in Victorian Visual Culture

contributor:
Helland, Janice
Art History

subject:
Omnibus
Horsebus
Modernity
London
Victorian
Public transport
Gender
Space
Punch
illustrated sheet music

abstract: In nineteenth-century Britain, the omnibus, a horse-drawn public bus, profoundly changed the nature of urban space. It was the first mass public transport technology in London and as such, fulfilled the mobility needs of the growing middle classes. Because of its novel function and eventual ubiquity on the streets of the capital, it appears as the subject for a variety of visual materials produced during the period. This project examines Victorian paintings, illustrations, sheet music, and print materials that depict people in and around omnibuses from the perspective of their production, content, circulation, and critical reception. It identifies a number of themes that can be organized along spatial, gender, and class lines and which, taken together, point to the concerns and anxieties felt by the passenger populace. Overall, this project looks to visual culture to explore how the Victorians navigated what was becoming a more spatially democratic world, and how different urban spaces structured the experience of the modern city.

abstract: PhD


title: Reference Electrode Development in Polymer Electrolyte Membrane (PEM) Electrolyzer Assembly for Novel Investigation of Electrodes

contributor:
Peppley, Brant
Chemical Engineering

subject: Polymer Electrolyte Membrane Electrolyzer

subject: Reference Electrode

subject: Polarization curve

subject: Hydrogen

subject: Sustainability

abstract:
Polymer electrolyte membrane electrolyzers (PEMEs) are the key to integrating renewable energy generation with energy storage to reduce greenhouse gas emissions that contribute to global climate change. The commercialization of large PEME systems, however, requires improvements to electrode design, performance, and reduction of material costs. In particular, reducing the precious metal loading at the oxygen producing electrode (anode) is critical to making PEME commercially competitive.

Measuring the electrode potentials separately is imperative to understanding and improving cell performance. A reliable reference electrode (RE) can provide much more precise information about the anode performance. A RE was developed for PEME application. The efficacy of the RE was confirmed by two parametric studies. The first parametric study served to demonstrate that the combined individual electrode potentials measured with the RE were exactly consistent with the overall potential difference of the cell. A second parametric study confirmed sufficient hydrogen polarization of the RE for operating conditions at low current density, low temperature, and low water feed rates.

Application of the RE was successfully demonstrated through investigation of the oxygen evolution and hydrogen evolution reaction mechanisms occurring at the anode and cathode, respectively. Tafel slopes were calculated and the rate determining steps were determined that support specific proposed reaction mechanisms reported in literature. This investigation revealed important characteristics of each electrode. In particular, it was shown that the cathode overvoltage should not be assumed negligible for the ohmic controlled operating region and more precise information can be observed for the anode performance. These results demonstrate the necessity of the in-situ RE to improving PEME performance.

abstract: M.Sc.


title: Faces of the Courtroom: How the Visual Elements of Portraiture Contribute to the Construction and Communication of Courtroom Sketches

contributor:
Dickey, Stephanie S.
Art History

subject:
Courtroom Sketches
Portraiture Theory
Criminal
Visual Elements
Media Communication
Canadian law

abstract: The purpose of this study is to interrogate the composition and influence of courtroom sketches from an art historical perspective with the aim of demonstrating not only their importance in the public’s understanding of the Canadian legal system, but also their ability to shape and challenge our perception of the individuals that appear before the courts. Specifically, this study focuses on the ways that art historical portrait theory can contextualize the construction and legibility of a courtroom sketch. The question of how courtroom sketches use the visual elements of portraiture to represent participants at a trial is applied to three case studies: the sentencing hearing of former colonel Russell Williams, the trial of Jian Ghomeshi, and the trial of Senator Mike Duffy. Each case took place in the Ontario criminal justice system and produced significant media attention resulting in a large number of sketches from various artists. The correlations identified and discussed in this study between the courtroom sketch and the practices of portraiture demonstrate that the historical conventions of representations are inextricable from the construction of images in contemporary media. In addition, this analysis serves to extricate the courtroom sketch from its traditional role as support for a textual report of legal events to a more accurate role as a primary source of information dissemination to the public.

abstract: M.A.


title: Intelligence-Led and Community-Based Policing: The Effects on Community Relations

contributor:
Sytsma, Victoria
Sociology

subject: Police

subject: Procedural Justice and Police Legitimacy

subject: Community-Oriented Policing

subject: Intelligence-Led Policing

abstract: As the police organization evolves to meet the ever-changing needs of the 21st century, policing styles and philosophies continue to innovate in an attempt to reduce crime and maintain order. Each fluctuation in policing style has affected the public, particularly minority groups, in its own specific manner. This paper discusses these fluctuations in policing in Canada with a focus on the most recent and popular styles of policing: community-oriented and intelligence-led policing, as implemented under the Ontario Mobilization and Engagement Model (OMEM) in 2010. Specifically, through a survey study with officers from Waterloo Regional Police Services this work seeks to examine whether police officers who have been hired and trained under OMEM are more supportive of community-oriented and intelligence-led policing styles than officers hired previously, and whether these officers differ in their perceptions of the relationships between police and minority communities. Empirical work is framed though a procedural justice lens, and posits that police legitimacy, and thus community relations and public support, are directly affected by officers operating in a procedurally just manner. It is argued here that procedural justice is inherent in community-oriented policing activities, and thus, officers who are trained under OMEM will be supportive of community-oriented policing and will behave in a more procedurally just manner, increasing police legitimacy and improving community relations. Results indicate that full organizational change did not occur following OMEM, with officers hired after OMEM showing more support for some COP and ILP activities but not necessarily engaging in them more. In some cases, officers hired after OMEM were more likely to be critical of community relations and to report greater divisiveness with different minority groups. This suggests that while OMEM may raise awareness and support, there is still a lack of full organizational engagement with COP and ILP. These results have implications for policy, suggesting that a greater proportion of resources need to be committed to long-term community-oriented policing activities, with particular attention paid to new immigrants in the region, in order to fully incorporate COP and ILP activities into all aspects of police work.

abstract: M.A.


title: The Age of Constitutionalism: Crisis, Rebellion, and Dissent in Eighteenth-Century Colonial North America

contributor:
Errington, Jane
History

subject:
American Revolution
Loyalist Ideology
Loyalism
British Constitutionalism

abstract: This thesis examines the role of constitutional thought in the development of colonial American resistance to the authority of the British state. It argues that beginning in 1765 American colonists recognized the need for constitutional reform in order to mitigate imperial power from London. At the same time, these debates had between colonists on the continent, and Britons in the metropole, were the product of a growing democratic spirit. This spirit that past historians have argued to have only been present in people who took up the revolutionary cause was likewise informing more moderate ideologies that sought out peaceable reform over a violent independence. At the onset of war, American colonists who refused to take up arms against the British became the enemies of the larger republican movement, which moderates had interpreted as jeopardizing the degree of liberty guaranteed by a connection to the British Constitution. By 1783, thousands of American colonists who refused to join in the rebel cause entered into an exile that propelled them into the British Atlantic world. Of the nearly fifty thousand who would leave the newly independent Thirteen Colonies, nearly thirty thousand would arrive and settle on the shores of the Fundy coast. Once there, American refugees continued to exhibit principles and beliefs that were democratic in nature, mirroring those of their more rebellious counterparts. In doing so, the refugees that arrived in the Atlantic region of modern-day Maritime Canada demonstrate the enduring legacy of American-born democratic attitudes, which shaped the development of new colonial societies throughout their diaspora.

abstract: M.A.


title: Characterization of the Multidirectional Strength of the Neck and of the Neuromuscular Coordination of the Superficial Neck Muscles

contributor:
Pelland, Lucie
Rehabilitation Science

subject:
Neck muscles
Electromyography
Upper Cervical Spine
Impulsive Neck Strength
Neuromuscular Coordination
Ballistic-Intent Training

abstract:
The goal of this dissertation is to enhance our knowledge of the three-dimensional impulsive strength capacity available at the upper cervical spine and its anticipatory neuromuscular control of the superficial neck muscles by characterizing relevant strength- and muscle activity outcome variables.
A scoping review was conducted to critically appraise the level and quality of evidence relating neck strength and neck muscle resistance training to the incidence of concussion in contact sports. Our analysis did not support the position that peak isometric strength lowers the impact severity of hits to the head. We identified the need to investigate short-latency, impulsive strength capacity and feedforward muscle activity as a potential strategy to decrease risk of head injury.
The first study characterized the effects of head posture on the multidirectional modulation of neck strength. Results demonstrated that the upper cervical spine has a significantly decreased strength capacity compared to the lower portion, due to smaller mechanical moment arm. Impulsive static strength capacity was also significantly decreased when exerting efforts along diagonal planes and positioned in 20˚ head flexion posture.
The second study characterized the anticipatory neuromuscular activity of the superficial neck muscles during multidirectional, ballistic-intent static contractions. The central nervous system utilizes simplifying intermuscular coordination synergies during the anticipatory phase of a ballistic-intent muscle contraction. The feedforward activities of posterior muscles frequently predict high magnitudes of static impulse generation at the upper cervical spine and are most influenced by peripheral sensory inputs induced by head flexion posture.
The third study evaluated the effects of a simple repetitive ballistic-intent training stimulus to facilitate an acute increase in early-phase neck strength capacity and muscle activation. The single-bout of ten ballistic-intent static maximal efforts produced significant and clinically meaningful acute increases in early-phase neck strength capacity and feedforward muscle activity that persisted for at least two days post-training.
Through our biomechanical platform, we have enhanced our understanding of how neck muscle strength capacity and activation contribute to the stability of the upper cervical spine, which serves to increase our ability to diagnose, rehabilitate, and ultimately develop strategies to prevent head and upper cervical spine injuries.

abstract: PhD


title: Sex Determination and Population Genetics of Smallmouth Bass (Micropterus dolomieu) in Eastern Lake Ontario

contributor:
Tufts, Bruce
Biology

rights: Attribution-ShareAlike 3.0 United States

subject:
Sex Determination
Population Genetics
Smallmouth Bass
Fisheries Management

abstract: Conserving genetic diversity within a population increases both its fitness and adaptability to environmental change; however, conservation management units frequently mismatch underlying genetic structure. Further challenges are introduced when quantifying genetic diversity, as the sex ratio and geographic distribution of samples can bias measures of population differentiation. Smallmouth Bass (SMB: Micropterus dolomieu) are an economically and ecologically valuable species of territorial freshwater fish. Regulated as a single unit across Lake Ontario and the St. Lawrence River, SMB are subject to regular anthropogenic dislocation through recreational angling. Since sex is not readily discernible from external morphology, and the genetic mechanism of sex determination is presently uncharacterized, typical SMB sex identification requires lethal autopsy. For this thesis I investigated the association of genomic markers with sex and geography for Smallmouth Bass in Eastern Lake Ontario, to improve the accuracy of phylogeographic study and subsequent conservation in the area. I hypothesized that Smallmouth Bass have an XY chromosomal system, and that genomic markers alone could identify sex. This hypothesis was tested using next-generation DNA sequencing of MluCI-SphI restriction digest associated loci from tournament-angled SMB mortalities. Although no sex-specific markers were present in males (or females), refuting the XY (and ZW) chromosome hypothesis, a leave-one-out predictive model generated with seven single nucleotide polymorphisms (SNPs) correctly predicted the sex of all 23 SMB and a reference female Florida Bass (Micropterus floridanus). Flanking DNA associated with these SNPs was then BLAST-searched against an assembled SMB transcriptome and NCBI’s swissprot database; however, no homology to sex-determining factors was found. I also hypothesized that genetic structure existed within tournament mortalities, which was confirmed following hierarchical K-selection analysis of 2,138 SNPs, indicating an optimal group number of two. Although some group assignments at higher K-values corresponded to approximate geographic location, the sample size of these subpopulations was too small to draw meaningful conclusions. To address this limitation, DNA was also quantified from 228 SMB angled across Lake Ontario to facilitate future fine-scale population structure analysis. Overall, these findings can be used to better manage the SMB fishery in Eastern Lake Ontario and provide a basis for further study.

abstract: M.Sc.


title: Self-Perception in Autism Spectrum Disorder

contributor:
Kelley, Elizabeth
Psychology

subject:
Autism
ASD
Self-Perception
Self
Self-Concept
Cognition
Episodic Memory
Social Motivation
Feedback

abstract:
Recent research suggests that individuals with Autism Spectrum Disorder (ASD) are unaware of their competencies in a variety of domains and overestimate their competencies above what is normative in the general population. The current research contributes to our understanding of self-perception in children with ASD by examining whether self-perception of academic competencies differs in children with ASD compared to typically-developing (TD) controls. It also examines whether estimations of competency change after providing feedback on a task, and if parameters such as reaction time and confidence relate to perceptions. Finally, it explores other possible factors that are related to self-perception.
 	Sixty participants, 10 to 15 years of age, completed academic tasks that consisted of verbal and math questions. Participants were asked to predict their performance before and after the tasks and were asked to rate their confidence in these predictions. The ASD group significantly overestimated their performance compared to the TD group, before and after completing the academic task. Overestimation occurred regardless of whether they were asked how many questions they would answer correctly or incorrectly. There were no differences between the groups on their confidence ratings of their performance on the tasks, suggesting that children with ASD are not overly confident in their predictions. When provided with feedback, the ASD group did not differ from the TD group in their perceptions. The ASD group was significantly more accurate with their perceptions when receiving feedback compared to no feedback, which suggests that they are able to process concrete feedback. Confidence ratings were not related to making more accurate predictions, and the length of time participants took to predict their performance did not affect accuracy in either group. Finally, the project examined two factors related to self-perception: episodic memory and social motivation did not predict self-perception in either group.
This research provides insight into how individuals with ASD overestimate their academic competencies and helps us understand more about whether children with ASD process concrete feedback when self-evaluating. Future research should attempt to understand the underlying mechanisms and function of overestimations of competencies.

abstract: PhD


title: The illusion of Inclusion for Children with Invisible Disabilities in Ontario Public Schools

contributor:
Kobayashi, Audrey
Cultural Studies

subject:
Invisible Disabilities
Inclusion

abstract: The current study examined inclusive education in Ontario public schools, as it is experienced by students with invisible disabilities and their families. Invisible disabilities are those that are not immediately visible to the naked eye. Some invisible disabilities that commonly affect children include (but are not limited to) high functioning autism spectrum disorder, attention deficit disorder, externalizing behaviours, depression/anxiety, and oppositional defiant disorder. Most literature to date focuses upon teacher/administrative perspectives of inclusion, while experiential data from families is absent. Parents, recruited through various community organizations and Quintilian Private School, completed of a survey on their families’ experiences within the Ontario public school system. Students with invisible disabilities completed an adapted photovoice exercise, where they shared a visual and textual summary of their feelings about public school and specialized private school, respectively. It was discovered that inclusive education for children with invisible disabilities is more an illusion than a reality in Ontario public schools.

abstract: M.A.


title: Memory, Childhood, and the Creation of Identities and Difference: Examining International Evacuation from Britain to Canada, 1938-1945.

contributor:
Adelman, Howard
History

subject:
Immigration
World War II
Evacuation
Britain
Canada
Child Migration
Anglo-Jewry
Jewish Canadian History

abstract:
Between 1939 and 1945, Canada welcomed more than 10,000 British guest children into the country to escape the threats to their safety posed by the Battle of Britain and by German hostilities generally. For these children, the Canadian government loosened immigration restrictions, provided free transport from Britain, and took responsibility for arranging their schooling, housing, and medical treatment. Many Canadians supported this effort and welcomed the guest children into their homes. This outpouring of support for British evacuees contrasts sharply with Canada’s treatment of other asylum seekers in the Second World War period. As Irving Abella and Harold Troper famously argue in None is Too Many: Canada and the Jews of Europe 1933-1948 (1982), the Canadian government was specifically unwelcoming to Jewish immigrants and refugees fleeing the Holocaust —often coming from Central and Eastern Europe—when they needed protection most. Yet hundreds of the British children who were evacuated to Canada were Jewish, and their presence in this movement has thus far been understudied and unaccounted for by historians of Canadian immigration.
This study investigates the movement of these fortunate British children, and especially of the British Jewish children; how their evacuation to Canada was justified by both British and Canadian governments; and why they were deemed worth saving when others were not. It explores the government policies of Britain and Canada that made this evacuation possible, even desirable; the work of agencies that facilitated the children’s settlement, such as Children’s Aid Societies and the Canadian Jewish Congress; and the decisions of the individual families that welcomed the children. It also explores the experiences of the children themselves who, far from home, adapted—or not—to the new homes where they settled “for the duration” of the war.

abstract: M.A.


title: Nietzsche's Idea of the Overman and the Current State of Collective Consciousness

contributor:
Fairfield, Paul
Philosophy

subject:
Overman
Collective Consciousness
Will to Power
Eternal Recurrence

abstract:
Nietzsche’s idea of the overman has been interpreted in several ways and is often misunderstood.
Observing people’s tendencies to act in specific ways along with the common forms of social
organization and development provide us with a general overview of the collective
consciousness, which suggests that many individuals are uncritical, conformist, and unhappy. The
present work argues that the overman is a concept that aims toward the spiritual growth of the
individual: overcoming the human means to reconcile with our true nature and achieve mastery
of oneself. As an ideal, the overman has the potential to serve as a guide that helps the subject to
better live their lives, regardless of its particular traits. If one succeeds in the task, the individual
will empower him- or herself, and this leads to better societies eventually.

abstract: M.A.


title: Context-Aware and Real-time Entrustment Framework for Securing Next Generation Internet Communications

contributor:
Hassanein, Hossam
Taha, Abd-Elhamid
Computing

subject:
Communication Security
Entrustment
Security Framework
Next Generation Internet
IoT
Context-Aware
Adaptive Security
Cryptography
Hashing
Privacy
Tracing
Resource Management
Security Aiding
Resource Aiding

abstract:
The Internet has been repeatedly demonstrated to be insufficiently secure for transferring sensitive information worldwide. This insecurity is an inherent characteristic as the Internet did not make any security considerations in its initial design. Rather, as is famously known, it was designed to connect “mutually trusting users”. Such void motivated a long and extensive history of a variety of trust measures to secure Internet communications at its different levels or layers. To date, however, the proposed security measures have been identified as computationally demanding, especially as they utilize cryptographic computations. In light of the evolution of the Internet-of-Things (IoT) and therefore the growing reliance on elements with limited capabilities (in terms of computing and/or energy), facilitating security becomes an equally increasing challenge. Such elements include embedded systems, sensors/actuators, small-scale mobile and wireless devices, in addition to various elements utilized in real-time and/or delay-critical applications. Considerations must therefore be made for addressing the computational challenge while providing the required security. In the meanwhile, any meaningful security solution must be global (i.e., Internet-wide) in its operation.
Our objective in this thesis is to demonstrate that an adaptive, end-to-end security solution for the next generation Internet is viable. Integral to our thesis is a holistic and innovative proposal for a Context-Aware and Real-time Entrustment framework or (CARE). The framework comprises a set of security components and modules designed to satisfy the observed and expected needs of next generation computing networks and their elements. While introducing the components and operations of our framework, we showcase how they can help into providing security services for the futuristic NGI communication trends. We then introduce a new approach in empirical analysis for cryptographic functions through which their use of computation resource can be identified and/or predicted. The outcome of this approach is applied in designing a robust security adaptation strategy for the CARE framework. A complementary resource-aide system is also presented in order to facilitate the secure end-to-end operation.

abstract: PhD


title: A Feminist Perspective of Activism in Argentina’s Dictatorship and The Disappeared, 1976-1983

contributor:
Libedinsky, Mariela
Sociology

subject: Feminism Activism Argentina Dictatorship Politics Sociology

abstract: This thesis is a literary, oral, historical, and political observation and analysis of Argentinean life. When responses to the Argentine dictatorship of the 70s and 80s are viewed through a feminist lens, patterns are discovered. These are confirmed in interviews with four women who experienced the dictatorship in different ways. The interviews support the conclusion that education, building a social movement, opening creative spaces, and understanding the effects of dominance and toleration are vital to understanding a community’s responses to the dictatorship. It is through an exploration of these main themes, together with an account of Argentinian independent literature, a victims’ report, and the current status of activist circles that a clearer picture of the country’s status can be imagined. Further ideas are explored such as the conditions required for civil conflict to arise, and how women’s experiences with activism and emotion may be analyzed and understood.

abstract: M.A.


title: Evaluating Synthetic Actin Targeting Compounds for Use in a HER2 Targeted Cancer Therapeutic

contributor:
Allingham, John
Craig, Andrew
Biomedical and Molecular Sciences

subject:
HER2+
Cancer Metastasis
Actin-Targeting
Actin Toxin
Mycalolide B

abstract: Human Epidermal Growth Factor Receptor-2 (HER2) is a driver and clinical target in a subset of breast and ovarian cancers with high rates of metastasis. Metastatic cancer cells require rapid actin polymerization and remodeling. This vulnerability can be exploited with marine macrolide toxins targeting actin; however, to achieve clinical benefits, we must overcome the limited availability and delivery mechanisms for these actin toxins. The goal of this thesis is to test the vulnerability of metastatic HER2-positive (HER2+) cancer cells to the marine macrolide toxin Mycalolide B (Myc B) and a series of novel synthetic analogs. The effects of Myc B and analogs on HER2+ breast and ovarian cancer cell lines (HCC1954, SKOV3) were measured in cell viability, motility and invasion assays. Myc B showed potent growth suppressive and cytotoxic effects on HER2+ cancer cells. At sub-lethal doses, Myc B caused rapid loss of leading edge protrusions, and sustained defects in HER2+ cancer cell motility and invasion. Myc B treatment was compatible with killing of HER2+ cancer cells by the clinically used HER2 inhibitor Trastuzumab-emtansine (T-DM1). In a HER2+ tumor xenograft model, intratumoral injections of Myc B reduced tumor growth and metastasis, and was most effective when combined with Trastuzumab. To address the limited availability of Myc B, we screened a panel of synthetic analogs of Myc B, and identified several capable of promoting the collapse of the actin cytoskeleton in HER2+ cancer cells, leading to increased cytotoxicity, growth suppression and impaired cell motility. With further optimization of Myc B analogs, we can develop delivery systems, including novel antibody-drug conjugates that limit metastasis in HER2+ cancers.

abstract: M.Sc.


title: Industrial-Scale Autonomous Vehicle Path Following by Feedback Linearized Iterative Learning Control

contributor:
Marshall, Joshua
Mechanical and Materials Engineering

subject:
Iterative Learning Control
Path Following
Autonomous Vehicle
Field Robotics
Industrial Scale
Feedback Linearization
Wheeled Vehicle
Center Articulated
ILC
Mining Robotics

abstract: This work describes and demonstrates, through simulation and field trials, a technique for autonomous wheeled vehicle path following that uses iterative learning control (ILC) performed in a feedback linearized space to augment a base feedback linearization (FBL) path-following controller. The goal of ILC is to iteratively adjust steering rate inputs to account for unmodelled vehicle dynamics, environmental disturbances, and extreme path geometries. One fundamental advantage of this approach is that ILC can be used without having to employ approximate linearization at every time step, rendering the approach easily implementable and computationally inexpensive when compared with traditional approaches. The technique was validated by performing field trials using large industrial-scale autonomous underground mining vehicles. The presented work not only demonstrates the underlying technique in the field on commercial vehicles, but also proposes and validates a method for parallel speed learning, wherein the speed can be adjusted over subsequent learning trials to improve productivity. Finally, a method for pre-learning through simulation prior to deployment in the field is introduced in order to reduce initial path-following errors.

abstract: M.A.Sc.


title: Hydrolytically Degradable Cationic Flocculants For Improved Water Recovery From Mature Fine Tailings

contributor:
Hutchinson, Robin A. Jr
Chemical Engineering

subject:
Biodegradable Polymers
Mature Fine Tailings
Flocculation
Sediments Dewatering
Sediments Consolidation

abstract: Oil sands mining operations in Canada produce large volumes of waste tailings that are difficult to dewater using commercial polyacrylamide-based flocculants. Recently, a novel hydrolytically-degradable polymer was synthesized through micellar radical polymerization of short-chain polyester cationic macromonomers. Poly(PCL2ChMA), made of polycaprolactone choline iodide ester methacrylate with two polyester units, effectively treated mature fine tailings (MFT) solutions as evaluated by measuring initial settling rate, supernatant turbidity, and capillary suction time (CST) of the sediments. Moreover, the novel materials become more hydrophobic with time, leading to an 85% reduction in CST after accelerated degradation for one week at 85 °C. The achievements described in this follow-up work are twofold. First, a procedure was developed to directly measure the extent of sediment dewatering that results from the polymer degradation, as previously the performance was indirectly inferred through CST measurements. Second, an investigation of the relationship between macromonomer structure and the performance of the polymer flocculant has led to the development of an improved material. Neither the substitution of PCL with poly(lactic acid) (PLA) units or replacement of the methacrylate functionality with acrylate greatly affects the ability of the resulting cationic flocculants to settle and separate the sediments in diluted MFT solutions because the synthesized polymers had similar charge densities and molecular weights. However, the faster degradation rates of the PLA-based materials lead to significantly faster dewatering of the sediments. 50% compaction was observed in PLA-polymer flocculated samples held for 5 days at 50 °C, whereas it was necessary to increase the temperature to 85 °C to achieve the same dewatering with the PCL-polymer flocculated samples. As a comparison, it was found that dewatering did not occur when the MFT material was flocculated with a non-degradable cationic polymer, non-ionic PAM, and commercial anionic FLOPAM A3338. A similar 50% compaction occurs in MFT sediments flocculated with LA-based polymers held at room temperature over several weeks, indicating that these materials degrade at a fast enough rate to provide solids compaction under field conditions.

abstract: M.A.Sc.


title: To Be North American but Not American: The Transformation of Canadian Studies and Canadian Universities

contributor:
Brison, Jeffrey
History

subject:
Canadianization
Americanization
Canadian Studies
Canadian Universities
Universities

abstract: The Canadianization movement emerged in the late 1960s and early 1970s from Canadian universities and has been treated as a brief moment in the historiography of Canada’s 1960s, post-secondary education in Canada and broader Americanization of Canadian society. The historical figureheads of the movement, Robin Mathews and James Steele, advocated for the hiring of Canadian faculty and increased Canadian content in universities across Canada. When a broader lens is used to view the Canadianization movement, it becomes apparent that the movement was the beginning of efforts to develop Canadian Studies as an interdisciplinary project in Canadian universities. Canadianizing efforts examined course content, curricula and personnel (including faculty, graduate students, and administrators) in order to foster a unique Canadian identity through the promotion of Canadian education. These studies were the origins of a number of Canadian university hiring policies and practices in place today. The Canadianization movement needs to be considered a broader movement–both chronologically and outside the involvement of Mathews and Steele–because, when it is expanded to encompass other organizations and reports that supported explicit Canadianization goals, such as the Canadian Association of University Teachers (CAUT), the Committee for an Independent Canada, the Symons’s Report, and David Cameron’s Taking Stock, the movement’s importance to Canadian education and Canadian identity becomes readily apparent.

abstract: M.A.


title: Two Confessions, One Jerusalem: Conceptions of Jews and Jerusalem in the Early Modern English Sermon

contributor:
Collins, Jeffrey
History

subject:
Reformation
England
Early Modern
Jewish History
Jerusalem
Antisemitism
Sermons

abstract: Jews and their city of Jerusalem have been a perpetual source of discussion within Christendom. The English Reformation became more established under the Elizabethan settlement of 1559. This fundamental change in religious practice and belief also reflected a difference in how Jewish people and their holy city of Jerusalem were portrayed within sermons and other tracts written by preachers. This project explores the place of Jews and Jerusalem in the sermons of early modern English preachers. It examines questions relating to the how Jews and Jerusalem factor into the content of English sermons written between 1558-1630, focusing on four distinct themes. The first section examines the heavenly versus the earthly Jerusalem, tracing the division of the city between an earthly and heavenly place from early Church figures through to English preachers. The next section follows the usage of Jewish figures and Hebrew texts, primarily pursuing inquiry relating to two major figures, Josephus and Maimonides. Further, this project contributes to scholarship that has recognized the antisemitism prevalent throughout early modern Europe. It examines how Jews were made other and insulted in sermons, as well as compared to Catholics. It pays particular attention to how attributes assigned to biblical Jews continued to impact their early modern descendants. Finally, this project considers the replies from Catholic English Jesuits to the English Protestant settlement. It investigates how Catholics reacted and responded to Protestant claims to Jerusalem by bolstering their own associations with the city. Further, it studies how Catholics in turn would associate Protestants with Jews and "Judaizing" practices. Above all, this project's aim is to place further attention upon the uses of Jews and Jerusalem within this turbulent and formative period within English Reformation history.

abstract: M.A.


title: The Impact of the Adoption of a Patient Rostering Model on Patient Access and Continuity of Care

contributor:
Green, Michael
Dahrouge, Simone
Public Health Sciences

subject:
Primary Care
Patient Rostering
Patient Access
Continuity of Care
Primary Care Reform
Pimary Care Model

abstract:
Context: Greater continuity and access to primary care results in improved patient health, satisfaction, and reduced healthcare costs. Although patient rostering is considered to be a cornerstone of a high performing primary care system and is believed to improve continuity and access, few studies have examined these relationships.
Objective: Examine the impact of the adoption of a patient rostering enhanced fee-for-service model (eFFS) on continuity, coordination of specialized care, and access.
Design: Population-based longitudinal study using health administrative data. Setting: Urban family practices in Ontario, Canada. Participants: Family physicians that transitioned from traditional FFS (tFFS) to eFFS between 2004 and 2013 were followed overtime. Physicians providing comprehensive primary care that had at least four years of pre-transition and two years of post-transition data were eligible. Patients were attributed to physicians on an annual basis by determining the provider that billed the largest dollar amount over a two year period.  Outcomes: 1) Continuity (usual provider of care index (UPC)), 2) Coordination of specialized care (Referral index (RI): % of total primary care referrals for a physician’s roster made by main provider), 3) Emergency department visits for family practice sensitive conditions (FPSCs). Analysis: Mixed-effects segmented linear and logistic regressions were used to examine changes in outcomes while controlling for patient and provider contextual factors.
Results: Prior to transitioning, UPC was decreasing at a rate of 0.27%/year (95% CI: -0.34 to -0.21, p<0.0001). Following the transition, UPC began decreasing by an additional 0.59%/year (95% CI: -0.69 to -0.49, p<0.0001) compared to the pre-transition rate. RI decreased by an additional 0.34%/year (95% CI: -0.43 to -0.24, p<0.0001) relative to the pre-transition period, where it had been stable. The transition had minimal impact on FPSC ED visits.
Conclusion: Continuity and coordination of specialized care slightly decreased upon transition from tFFS to eFFS. This is likely due to physicians working in groups and sharing patients following the transition to the eFFS model.  Adoption of an enrolment model with after-hours care did not decrease non-urgent ED use, which may reflect the small impact that primary care access has on these types of ED visits.

abstract: M.Sc.


title: Characterization Of Large Area Avalanche Photodiodes For The Measurement Of The Electron Capture Decay Of 40K To The Ground State Of 40Ar

contributor: Physics, Engineering Physics and Astronomy

subject:
Potassium
K-40
Avalanche Photodiode
DAMA
Electron Capture
Modular Total Absorbtion Spectrometer
MTAS
KDK
Third Unique Forbidden Decay

abstract: The branching ratio of the direct decay of 40K to the ground state of 40Ar through electron capture has never been experimentally measured. This rate has been shown to be vital in constraining the DAMA/LIBRA (DArk MAtter/Large sodium Iodide Bulk for RAre processes) dark matter signal claim and is a rare example of a unique third forbidden decay. The KDK (pun for Potassium Decay) project attempts to measure the ratio of electron capture to the excited state of 40Ar versus the electron capture to its ground state. The experiment will combine an enriched 40K source attached to a low energy x-ray detector surrounded by an almost 4pi coverage gamma ray detector. The low energy x-ray detector will be a Large Area Avalanche Photodiode, while the gamma ray detector will be the Modular Total Absorption Spectrometer at Oak Ridge National Laboratory. This thesis focuses on the development, characterization and feasibility of avalanche photodiodes as low energy x-ray detectors for the KDK measurement.

abstract: M.Sc.


title: An Injectable Hydrophobic Delivery Formulation Based on Poly(Trimethylene Carbonate) for Therapeutic Angiogenesis

contributor:
Amsden, Brian
Chemical Engineering

subject: Therapeutic Angiogenesis, Poly(trimethylene carbonate-co-5-hydroxyl trimethylene carbonate)

subject: Protein Delivery

subject: VEGF

subject: Hydrophobic Injectable Polymer

subject: Poly(trimethylene Carbonate-co-5-hydroxyl Trimethylene Carbonate)

abstract: The aim of this thesis was to determine the feasibility of an injectable delivery formulation based on low molecular weight poly(trimethylene carbonate) (PTMC) for localized delivery of vascular endothelial growth factor (VEGF). Formulations based on modified conjugated PTMC, ester or anhydride-linked PTMC, and poly(trimethylene carbonate-co-5-hydroxy trimethylene carbonate) (P(TMC-co-HTMC)), were synthesized. Polymers/copolymers were amorphous and injectable viscous liquids at 37 ºC. In vitro degradation study of the conjugated PTMCs showed that the anhydride bond cleaved within 24 hours, generating acidic products that lowered the pH of the buffered degradation medium. In contrast, hydrolysis of the ester bond did not result in an acidic pH; however, it degraded too slowly for the intended application. Preparing P(TMC-co-HTMC) using different catalysts revealed that HCl·Et2O is able to provide a random comonomer distribution and low toxicity burden. In vitro degradation of the resulting random copolymers was tailored by adjusting the initial HTMC content, initial molecular weight and the choice of initiator. During in vitro degradation, the pH of the medium surrounding the copolymer always remained near neutral. In vivo degradation study of P(TMC-co-HTMC)s at the molecular weight range of 1000-2000 Da with 30 mol% initial HTMC content revealed rapid degradation of the HTMC units followed by gradual elimination of the short chains produced via HTMC degradation. The inflammatory response to the injected copolymers subsided by time but was still ongoing after 22 weeks. The observed tissue response was comparable with the tissue response of a commercial MONOCRYL suture indicating that the copolymer can be considered biocompatible. In vitro protein release from the same copolymers was characterized by using lysozyme, bovine serum albumin and VEGF. This study revealed that the rate of protein release was controlled by the solubility of the lyophilized protein in the aqueous environment within the copolymer, the concentration of the salt included in the lyophilized powder, and the flexibility of the copolymer chains to form superhydrated regions. The released VEGF showed greater than 80% bioactivity throughout the release period. This delivery formulation can be used to deliver acid sensitive proteins for short or long-term delivery approaches depending on the protein physical properties.

abstract: PhD


title: Interval Versus Continuous Cognitive Training in Schizophrenia: Comparing Cognitive, Neurophysiological, and Subjective Outcomes

contributor:
Iftene, Felicia
Neuroscience Studies

subject:
Schizophrenia
Cognitive Remediation
Spacing Effect
Rest
Working Memory

abstract:
Background: Therapies aimed at remediating cognitive deficits in schizophrenia vary widely in their approach and delivery of cognitive training. In healthy populations, rest breaks have been shown to improve attention, performance, and subjective experience of work or cognitive tasks. Neurophysiological research has demonstrated a relationship between on-task band power, performance, and working memory load.
Objectives: The current study aimed to assess the effect of rest breaks during cognitive training in schizophrenia through examination of cognitive performance and improvement, mean theta and alpha power, and subjective measures focused on acceptability and intrinsic motivation.
Methods: 24 participants with schizophrenia completed three working memory tasks to assess baseline functioning and were randomized into either interval or continuous cognitive training on the N-back task, each with a total of 10-minutes of on-task training. Immediately following training, subjects completed the three working memory tasks again to assess immediate change in performance, and again following a 30-minute period of respite to assess durable change. Continuous EEG was recorded throughout, and following completion participants’ subjective experience of training was assessed with a self-report questionnaire.
Results: The interval training group performed significantly better than the continuous training group during the training period, however this did not lead to improvement differences at post-testing on the training task. For tasks not trained on, there was a trend for significantly greater improvement following interval training with medium effect size. No differences were observed in theta or alpha band power between groups during training, nor was band power found to be significantly correlated with task difficulty or performance. There were no significant differences between groups for subjective training experience.
Discussion: Results suggest that incorporating rest intervals in cognitive training leads to greater performance during training and enhanced skills transfer to other domains of working memory. This observation could be due to memory retention benefits of the spacing effect in the interval condition. Alternatively, results could be due to mental fatigue and/or ego depletion in the continuous condition, leading to a reduced capacity for performance and improvement on non-trained tasks. Further research is needed to determine the underlying mechanism of improvement and transfer.

abstract: M.Sc.


title: Self-Organization and Light-Induced Chirality in Azo-Glass Material

subject:
Diffraction Gratings
All-Optical Surface Patterning
Self-Organised Surface Relief Gratings
Anisotropic Optical Materials
Azobenzene
Molecular Glass
Chirality

abstract:
Azobenzene derivatives have been subject to many studies in the field of all-optical surface patterning due to their unique photoresponsive properties. Photoinduced mass movement of azobenzene enables inscription of surface relief gratings (SRG) under exposure to an interference pattern of light. Interestingly SRGs can form under single beam irradiation, where no external interference pattern is applied, and thus the structures form spontaneously. Herein, Photoinduction of spontaneous SRG (SSRG) on thin films of a disperse red 1 functionalized glass-forming compound is investigated. Glass-forming small molecules yield more homogeneous samples and it allows to mitigate the impact of the rheological effects of polymers.
SSRG formation is assumed to initiate from an interference pattern formed between the incident beam and scattered beams at grazing angle by surface defects. Formation of SSRG’s takes place in three stages: nucleation, growth, and saturation. Herein, the grating formation procedure is studied by monitoring the surface topology of thin films exposed to one writing beam for various periods of time, under both linear and circular polarizations, using AFM. Even in the absence of surface defects on the initial film, irradiation produces light-induced surface defects due to the reorientation and mass movement of the azo molecules. These defects act as seeds for SSRG around which gratings gradually emerge and propagate throughout the sample. To consolidate this hypothesis, the formation of gratings was studied on samples with controlled surface roughness. Pore-shaped defects do not diffract light on top of the sample, and thus have no impact on SSRG growth, while for hill-shaped defects, the growth rate decreases sharply with defect sizes larger than the writing beam wavelength. The saturation stage has been studied using different intensities of the writing beam. The rate of grating growth increases as a function of laser intensity, but the gratings saturate at the same modulation amplitude, independent of the laser intensity
Two other analogous glass-forming azobenzene derivatives were studied, and in all cases, SSRG formation was correlated with the induction of birefringence in the early stages of the irradiation. The orientation of SSRGs is influenced by the polarization of the writing beam. The direction of the gratings is determined by the optical anisotropy induced by a polarized beam. Real-time anisotropy experiments are presented to predict the grating direction. Furthermore, self-organized surface relief gratings formation under different polarizations at different incident angles was studied. Oblique irradiation of a beam polarized with a combination of p- and s-polarizations yields crossed SSRG with different pitches, forming planar chiral structures. Azimuth rotations up to 10° have been observed, and the absence of 3D chirality has been confirmed. This method thus allows generating non-reciprocal planar chiral objects by a simple, single irradiation process on a thin film of a material that can easily be processed over large areas or onto small objects.

abstract: PhD


title: Improvements in the Performance and Understanding of Switchable-Hydrophilicity Solvents

contributor:
Jessop, Philip
Chemistry

subject:
Green Chemistry
Solvents
Switchable Materials
Chemical Separations

abstract:
Switchable-hydrophilicity solvents (SHSs) are amine and amidine solvents that can be reversibly switched between two forms: one that forms a biphasic mixture with water and another that forms a monophasic mixture with water. The addition or removal of CO2 from SHS-based systems acts as the trigger to switch between these two forms. SHSs have attracted attention as alternative solvents for a variety of applications because their switchable behaviour allows them to be used in energy- or material- efficient ways. One such application is distillation-free solvent-solute separations. The present research builds an understanding of the properties of amines that determine whether they are SHSs or not. It also applies this understanding to the development of new SHSs with fewer health and environmental hazards, such as decreased acute toxicity and decreased volatility, as well as improved performance with respect to solvent-solute separations.
The relationship between the pKaH and log Kow of an amine and the ability of the amine to act as a SHS is established. A mathematical model is described that can be used to predict whether an amine acts as a SHS based on these two properties. Furthermore, the influence of CO2 partial pressure and the water/amine volume ratio on these pKaH and log Kow requirements are investigated. The model acts as a guide when identifying new SHSs.
Many new SHSs are identified with a variety of beneficial properties. SHSs that have oxygen-containing functional groups have decreased environmental, health, and safety risks than trialkylamine SHSs. Secondary amine SHSs are shown to switch to their hydrophilic state more rapidly than tertiary amine SHSs. Diamine SHSs can be more completely separated from solutes than monoamines, resulting in a more pure isolated solute after a SHS-based separation. A virtual screening approach to the design of SHSs is presented that can be used to rapidly screen thousands of compounds to identify those that are estimated to be SHSs with few environmental, health, and safety risks. The identification of new SHSs increases the options when selecting a solvent for a SHS-based process and provides data to improve the understanding of SHSs.

abstract: PhD