title: Arabidopsis Mitogen-Activated Protein Kinase Kinase Kinase Family Members and Their Possible Role in Innate Immunity

subject:
Plant biology
Plant immunity
Arabidopsis
Arabidopsis thaliana
Immunity
Mitogen-activated protein kinase
MAPK

abstract: From an early developmental stage, plants are exposed to both beneficial and pathogenic microbes. Upon pathogen detection, receptor complexes on the cell surface can detect conserved microbial molecules, such as bacterial flagellin, to elicit an immune response. Several early immune outputs are triggered by receptor complex activation, such as the activation of MITOGEN-ACTIVATED PROTEIN KINASE (MAPK) cascades and the production of extracellular reactive oxygen species, which ultimately confer broad-spectrum immunity. While this response is necessary for survival, it is energetically costly and can result in developmental trade-offs. The CALCIUM-DEPENDENT PROTEIN KINASE (CPK28) negatively regulates immune output downstream of multiple receptor complexes by promoting turnover of a key positive regulator of immunity. To identify novel positive and regulators of the plant immune response, putative CPK28-associated proteins were previously identified through affinity purification of wild-type and kinase-dead CPK28 from stable Arabidopsis thaliana lines both before and after immune elicitation, followed by liquid chromatography and tandem mass spectrometry. A putative MAPK KINASE KINASE (MAPKKK), MLK/RAF-RELATED PROTEIN KINASE 1 (MRK1), and two protein phosphatase regulatory subunits, PROTEIN PHOSPHATASE 2A (PP2A)-Bα and PP2A-Bβ, were identified in this screen as potential CPK28-associated proteins. The primary objective of my thesis was to examine the role of MRK1, MRK1-related family members, and the PP2A-B subunits in the plant innate immune response. Through functional characterization of double null lines, I found that MRK1 and two closely related proteins, Raf26 and Raf39, may negatively regulate immune-induced oxidative burst in a partially redundant manner. I also observed that MRK1 localizes to the cytosol in Arabidopsis, and present preliminary findings which suggest that MRK1 may play a role in normal rosette development. Taken together, this work suggests that MRK1 and related protein kinases may be acting as novel regulators of immunity, and primes future analysis on this previously unstudied family.

abstract: M.Sc.


title: Building Better Together: Understanding Interprofessional Collaboration and Student Perceptions in a Classroom Case Study

contributor:
Davies, T. Claire
Mechanical and Materials Engineering

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:
Interprofessional
Interdisciplinary
Education
Collaboration
Rehabilitation Science
Engineering

abstract:
The disciplines of rehabilitation sciences and engineering are known work extensively in teams and require the competencies for effective collaboration as outlined by each discipline’s regulatory body. To make a positive impact in their respective professions, students must learn with, from, and about each other to create and perform as effective players in a team environment. The course Building Better Together (BBT) was created as a collaborative learning and leadership initiative, that seeks to enable students to gain a deeper understanding of their respective roles during the design process.  To better understand the impacts of interprofessional education and the processes involved in team functioning in Building Better Together, three research objectives were developed. The first objective was to explore the behaviours exhibited during interdisciplinary collaboration in a classroom case study. The second objective was to determine if there were any links between the strength of the team’s collaboration and team grades. The third objective was to examine the students’ perspectives on learning and collaborating in an interdisciplinary environment.
Two studies were conducted to address these three objectives. The first study analyzed video footage of four teams to understand patterns in team behaviour and included links to course grades and peer assessments. Three key themes of interprofessional knowledge, partnership, and task focus were identified along with links between high course grades and strong team collaboration. The second study examined four self-report assessment tools to gain understanding of the student perspective on the skills required for interprofessional collaboration. Overall the students’ scores suggest they value the learning experience and feel that they are able to collaborate and learn as part of an interdisciplinary team.

abstract: M.A.Sc.


title: Heat Migration and Solute Transport in a Discrete Fracture

contributor:
Novakowski, Kent
Kueper, Bernard
Civil Engineering

subject: Thermal transport, Solute transport, fractured rock, variable aperture

abstract: The study of heat and solute transport in fractured rock can provide complementary information in aid of understanding the interaction between surface and groundwater, the long-term isolation of energy by products, the application of renewable energy storage systems, and the treatment of contaminated sites. Employing numerical modeling, this research was undertaken to assess the most influential factors controlling heat migration in discretely fractured rock under natural groundwater flow conditions, to address the effect of fracture aperture variability on the spatial distribution of a migrating thermal front, and to compare heat and solute transport mechanisms. Using factorial analyses, it is shown that the most influential factor controlling heat propagation in a single fracture setting is the velocity of the fluid in the fracture. The combination of effects of the thermal conductivity of the matrix with the velocity of the fluid, and of the thermal conductivity of the matrix with the aperture of the fracture dominantly control the attenuation of the thermal front migration. By integrating variable aperture fields with contact points, it is demonstrated that the effect of aperture variability on the spatial distribution of the thermal front is defined mainly by the thermal conductivity of the rock matrix. The effect of groundwater flow channeling on the spatial distribution of the thermal front is small, contrary to solute transport in a discrete fracture setting, where channeling is sometimes a major contributor to widespread solute migration rates and directions. The thermal plume in the fracture does not reach equilibrium over the 3-year period of the simulation in contrast to the solute plume that reaches steady state in less than ten days, mainly due to thermal conduction in the matrix which remains in disequilibrium. Two-dimensional conduction in the plane of the fracture and three-dimensional conduction in the matrix are important factors to consider when assessing the thermal plume in contrast to solute transport, whereas one-dimensional diffusion in the matrix and two-dimensional dispersion in the fracture are good assumptions.

abstract: PhD


title: Leveraging Q&A platforms to improve issue management in software projects

contributor:
Hassan, Ahmed
Computing

subject:
software engineering
issue reporting
stack exchange

abstract: Traditional issue management systems like Bugzilla are widely used in open source and commercial projects. Stack Exchange uses its online question and answer (Q&A) platform to manage bugs, which brings several new unique features that are not offered in traditional bug management systems.  In this thesis, we divide our study into the Q&A features that are being used in the Stack Exchange issue management system, as well as study the differences between bug reports and feature requests that have been refined due to community collaborations. For the former part, we study the unique features of Stack Exchange Q&A platform that allows users to directly edit a bug report (i.e., the in-place editing feature) instead of commenting about the bug report; use different communication channels (i.e., the answering and commenting features) to discuss reported bugs, and vote on those bug reports, answers, and their associated comments (i.e., the voting feature). We study how these unique features are used to manage bugs, and provide insights to the designers of traditional bug management systems who are considering introducing such features in their bug management system. The later part of this thesis performs a study of the differences between bug reports and feature requests in the Stack Exchange issue management system. We perform this study because: 1) Stack Exchange contains a large number of issues that have been carefully tagged as bug reports versus feature requests.  2) the issue management is carried out through a Q&A platform, which provides us with a richer perspective on the differences  between the  management of bug  reports and feature requests. We found that bug reports and feature requests differ significantly from each other along many dimensions such as the amount of community participation, the content of the issues, and the characteristics of the participating users. We are able to automatically identify bug reports from feature requests with a median AUC of 0.90. The developers of issue management systems, software practitioners and researchers can leverage such understanding to improve issue management processes in large software projects.

abstract: M.Sc.


title: Measurement of Pubic Symphysis Width in Different Birthing Positions Using Ultrasound

contributor:
Dumas, Genevieve
Hemmerich, Andrea
Mechanical and Materials Engineering

rights: Attribution-NonCommercial-NoDerivs 3.0 United States

subject: Pubic Symphysis width, birthing positions, 3D freehand ultrasound

abstract:
Studies have shown that certain postures, such as squatting and standing, may facilitate labour and birth and may be used by some practitioners. However, a rigorous biomechanical understanding of how different positions affect a woman’s pelvis during labour is currently lacking. It was hypothesized that there is a difference in relative pelvic bone position and orientation between different birthing positions that results in changes in pubic symphysis width. Therefore, we evaluated pubic symphysis width in positions that are used in clinics like lithotomy position and supine, and those suggested by midwives, such as standing and squatting, through three-dimensional (3D) reconstruction of pubic symphysis ultrasound images.
Eleven women in their seventh to ninth month of pregnancy were recruited to be participants. A 3D freehand ultrasound system was used to scan the pubic symphysis of each participant in the four birthing positions. Image and position data of the probe were acquired. In each position, images were resliced from the reconstructed 3D volume and the same landmarks at the superior and inferior parts of pubic symphysis were located.
The results were consistent with two comparable studies. The average superior and inferior pubic symphysis widths in lithotomy, squatting and standing positions were larger than those in the supine position by approximately 1mm. However, there was no significant difference between lithotomy, squatting and standing positions.
The angles between right and left bones were calculated in an anatomical coordinate system. A significant difference was only found between standing and squatting and lithotomy in the rotation angle about the medio-lateral axis.
The results suggest that positions with thigh hyperflexion and gravity effect make a difference in pubic symphysis width and might have a positive effect in childbirth. However, due to the small sample size, no definite conclusion can be drawn.

abstract: M.A.Sc.


title: Impact of Long- and Short-Term Geodynamic Processes on Hydrocarbon Reservoirs in the Grand Banks

contributor: Geological Sciences and Geological Engineering

subject:
Geophysics
Geodynamics
Numerical Modelling
Seismic Interpretation
Gravity
Glacial Isostatic Adjustment
Petroleum
Grand Banks

abstract: The evolution of the passive margin off the coast of Eastern Canada has been characterized by a series of rifting episodes beginning approximately 200 ma which caused widespread extension of the lithosphere and associated structural anomalies, some with the potential to be classified as a result of lithospheric boudinage. Crustal thinning of competent layers is often apparent in seismic sections, and deeper Moho undulations may appear as repeating elongated anomalies in gravity and magnetic surveys. This investigation supplements our knowledge of analogous examples which have been linked to boudinage as a driving mechanism, to determine that similar structures are evident in the context of the Grand Banks. More recently in the last 20 ka, the region has been subject to crustal warping and Glacial Isostatic Adjustment (GIA)-induced visco-elastic deformation. Numerical simulations were run using different rheological parameters and ice load histories to obtain a model which may be representative of the isostatic response for the Grand Banks. The goal was to assess the potential impact on hydrocarbon reservoirs and trapping structures as a consequence of GIA processes, which may include various deformation-related implications.. Comparisons may be drawn to related studies, including the postglacial implications on reservoirs in the Barents Sea, as well as validation of GIA model predictions using GPS and Canadian Base Network vertical motion data to determine a best-fitting model to the present-day observations. As a result of this study, it is clear that there are potential effects from GIA since the Last Glacial Maximum, and there is still vertical motion in the region meaning these effects may continue.

abstract: M.A.Sc.


title: Advanced Characterization of Hydrides in Zirconium

contributor:
Daymond, Mark
Mechanical and Materials Engineering

subject: Zirconium Hydride

subject: Changes in Zr-H System Associated with Hydride Dissolution/Precipitation

subject: Microscopy

subject: Synchrotron X-Ray Diffraction

abstract:
Zirconium and its alloys are of great importance to the nuclear power industry due to their unique combination of mechanical properties, low neutron-capture cross-section, and sufficient corrosion resistance under reducing water conditions. Zirconium alloys constitute most nuclear fuel claddings and structural components in CANDU and light water reactors. Despite many desirable material properties, zirconium is susceptible to a corrosion reaction that results in the gradual pick-up of hydrogen during service in nuclear power plants. Once the local hydrogen concentration exceeds the Terminal Solid Solubility of Precipitation, brittle hydrides can form. The precipitated hydride phase has been shown to degrade the bulk mechanical properties of zirconium cladding and introduce mechanisms for failure through delayed hydride cracking. The behavior of Zr-H system at low hydrogen concentrations continues to be the subject of research due to both its wide engineering application and the high complexity of the system.
An idea to consider not only each single phase participating in the hydride-matrix interaction but also different hydride orientations (relative to parent Zr texture) opens new horizons for investigation of the Zr-H system. The current study is the first attempt to provide insight regarding the micro-scale direction of possible hydrogen migration within the α-Zr matrix and to evaluate changes in local strains on the grain length scale in the Zr-H system undergoing hydride precipitation. Finally, the research presented in this thesis aimed to improve our understanding of the stability of the Zr-H system. Phase changes occurring in a sample immediately after electrolytic hydriding, was investigated along with a reverse conversion occurring in the as-hydrided sample upon prolonged ageing. Surface hydride formation and its transformation during ageing was inspected using advanced characterization techniques such as SEM and AFM imaging, EBSD, and X-ray diffraction.

abstract: PhD


title: Using gravity to help us understand the AMPK-PGC-1α axis in skeletal muscle from healthy young males

contributor:
Gurd, Brendon
Kinesiology and Health Studies

subject:
blood flow restriction
PGC-1α
aerobic exercise
skeletal muscle
mitochondria

abstract:
The mitochondrion is a critical component of the cell and is responsible for producing energy needed by our bodies. One way our body adapts to exercise is by enlarging and creating more mitochondria. A primary protein believed to be involved in regulating these exercise-induced mitochondrial changes is called peroxisome proliferator-activated gamma coactivator 1-alpha (PGC-1α). Generally, the harder someone exercises (i.e. higher exercise intensities), the more PGC-1α increases. There are also several proteins that ‘turn on’ or activate PGC-1α, and these too increase as exercise intensity goes up. This means exercise at a given intensity proportionately increases both PGC-1α and its activators. Consequently, it has been difficult for researchers to single out the impact of any one particular activator of PGC-1α on PGC-1α in human muscle.

If researchers experimentally reduce blood flow to exercising muscle, it could help them understand the effect of a particular PGC-1α activator on PGC-1α because some activators should be sensitive to amounts of oxygen in our muscle cells. Specifically, because blood flow restricted (BFR) aerobic exercise should reduce the amount of oxygen in exercising muscle, the role of a particular oxygen-sensitive PGC-1α activator may be better understood by using BFR and non-BFR aerobic exercise protocols to compare amounts of PGC-1α produced. Matching the intensity of these two protocols is important because that way the non-oxygen-sensitive PGC-1α activators can remain unchanged while the oxygen sensitive one(s) should increase.

Indeed, results from previous studies suggest that this may be the case, however these studies have two general limitations. First, the BFR models used in those studies are expensive and difficult to build. Second, these studies were conducted in a way that leaves them vulnerable to the influence of bias; bias matters because it may lead to potentially incorrect results and interpretations. Minimizing bias is an essential aspect of good research. Therefore, we developed an inexpensive BFR model that uses gravity to reduce muscle oxygenation, and we used experimental best practices to test our hypothesis that our BFR model would increase both PGC-1α and its oxygen-sensitive activator more than intensity-matched non-BFR aerobic exercise. Our results supported this hypothesis.

abstract: M.Sc.


title: Williams, Scanlon, and the Normativity of Morality

contributor:
Kumar, Rahul
Philosophy

subject:
Contractualism
Scanlon
Williams
Moral Theory
Integrity

abstract: Most debates about the viability of a given moral theory are won and lost, or at least brought to an end, through resort to a familiar pattern of argument: if a theory calls for that course of action, can it really claim to offer a substantively correct account of morality? This debate operates on the plausible premise that a moral theory rises and falls with the substantive correctness of its prescriptions. But this debate is also premised on the idea that moral theory has a claim to make on us. Not everyone grants this premise. Indeed, Bernard Williams’ work presents a denial of the claim that moral theory has the normative authority to demand anything of us at all. This familiar inversion of the claim that morality is overly demanding is a serious objection to the task of working out a moral theory. It suggests that interlocutors in the debate detailed above claim ground to which moral theory is not ultimately entitled. This thesis details Contractualism’s capacity to answer to this challenge. In particular, this thesis defends the idea that Contractualism offers an account of inter-personal morality that is substantively correct and accessible to integrated agents. Contractualism’s account of inter-personal wrongness, and the powerful reasons we have to avoid wronging others, satisfies the twin conditions of substantive correctness and normative coherence.

abstract: M.A.


title: Neural correlates and effects of increased cognitive load on performance during the n-back task in major depressive disorder

contributor:
Milev, Roumen
Bowie, Christopher
Neuroscience Studies

subject:
depression
major depressive disorder
cognition
n-back
cognitive load

abstract:
Background: Major depressive disorder (MDD) is a heterogenous disease that includes debilitating cognitive deficits, including working memory (WM). The n-back task used to examine WM as it requires continuous updating and recall. The present study examined the effects of MDD and cognitive load during the n-back task (0- and 2-back). The following were predicted, as cognitive load increased: (1) participants would display decreased accuracy and increased reaction time; (2) increased activity would be found in regions associated with WM; and (3) MDD symptoms and accuracy would be correlated with functional activity in these regions.
Methods: MDD patients (n = 29) completed the n-back task during a functional magnetic resonance imaging scan. Behavioural and imaging data were analysed between conditions. Montgomery-Åsberg Depression Rating Scale (MADRS) scores and task accuracy were correlated with functional activity for each participant.
Results: Compared to 0-back, participants demonstrated decreased accuracy and longer reaction times in the 2-back condition. During the 0-back condition, activity was seen in the bilateral insula and the middle occipital gyrus; in the 2-back condition, activity was seen in the middle and medial frontal gyri and the inferior parietal lobule. MADRS scores were not significantly correlated with activity in either condition. Activity in all regions identified in the 2-back condition were positively correlated with performance accuracy.
Discussion: In the 0-back condition, activated regions are associated with resting state activities and the processing of visual stimuli. Compared to the 0-back condition, higher levels of activity were found during 2-back in the middle and medial frontal gyri and inferior parietal lobule, which are associated with WM, visual processing, and complex cognitive processes, indicating that participants required more neural resources during the more difficult task. Significant and mid-sized effects were found in the 2-back condition between accuracy and activity in the middle and medial frontal gyri and inferior parietal lobule, suggesting that MDD patients require more effort to perform well in cognitively demanding tasks. Limitations include the small and largely female sample, which would be improved by including more participants and considering covariates.

abstract: M.Sc.


title: Natural Convective Heat Transfer From Horizontal and Inclined Two-Sided Bodies of Finite Thickness

contributor:
Oosthuizen, Patrick
Mechanical and Materials Engineering

subject:
Natural Convection
Two-Sided
Horizontal
Inclined
Non-flat
Numerical
Nanofluid
Finite Thickness

abstract:
Natural convective heat transfer from two-sided flat plates that are horizontal or inclined to the horizontal has been numerically and experimentally investigated. The objective of the study was to investigate the influence of changes in the plate thickness, of the boundary condition over the plate side surface, of the plate shape, and of the inclination angle on the heat transfer rate. A further objective was to investigate whether the heat transfer rate from a flat plate can be increased by using a plate having a non-flat surface. The heated elements considered were exposed to air. The heat transfer rate was numerically obtained by using the commercial CFD solver ANSYS FLUENT© and experimentally determined using the lumped capacity method.
In addition, natural convective heat transfer from bottom-heated rectangular enclosures that contain a nanofluid and which have various aspect ratios was numerically studied. The purpose was to determine whether the heat transfer rate from the heated bottom wall of the enclosure can be increased compared to that which would exist with pure water and to study the influence of the nanofluid nanoparticle concentration and of the enclosure aspect ratio on the heat transfer rate.
The results of the studies of natural convective heat transfer from heated plates indicated that the plate thickness and the thermal boundary condition have only a modest influence on the heat transfer rate from the bottom surface of the plate. The influence of the inclination angle on the heat transfer rate from the top surface of the plate is higher than its influence on that from the bottom surface. For the case of the plate having a non-flat surface, the results indicated that the heat transfer rate can be enhanced by using a non-flat surface but this enhancement is relatively small.
The results of the study of heat transfer across a nanofluid filled enclosure showed that the heat transfer rate is significantly increased by replacing pure water with a nanofluid (Cu-water) and by increasing the nanoparticle concentration. It was also found that the enclosure aspect ratio had only a small influence on the heat transfer rate.

abstract: PhD


title: Three Essays on Organizational Economics

contributor:
de Bettignies, Jean-Etienne
Business

subject:
Managerial Human Capital
Corporate Social Responsibility
Regulatory Oversight
Investment Strategy
Competition
Innovation
Import Tariff

abstract:
In the first essay, we build a model investigating how the nature of managerial human capital affects firms' choices of growth strategies. The model shows
that when firms are cash constrained, managers with more general managerial skills are more likely to foster growth via acquisitions, which is further moderated by firms’ financial slack and agency concern. We find empirical evidence supporting the model predictions. Moreover, we use variation in enforceability of non-compete agreements in U.S. states as an instrument for general managerial skills and find a positive and causal impact of general managerial skills on growth via acquisitions.

In the second essay, we study whether it is optimal for a firm to engage in corporate social responsibility (CSR) when regulatory oversight was imperfect. The model suggests that a regulator who cannot perfectly monitor firm compliance may have to set inefficiently loose regulation. It then becomes optimal for the firm to hire a socially responsible worker who chooses to engage more in CSR. We test the model in two ways. Using the EU sample, we find that firms on average had lower CSR ratings after the introduction of the mandatory disclosure policy than the firms from 15 European countries that did not have a mandatory disclosure policy in place. Using US sample, we find that industries most hit by outsourcing and globalization are those that increase their CSR scores the most. Both sets of results support the predictions of the model.

In the third essay, we study how competition between two downstream firms affects an upstream
innovator's innovation strategy, which includes selecting how much innovation to produce and whether to license this innovation to one (targeted licensing) or both (market-wide licensing) downstream competitors. Our model points to a U-shaped relationship between downstream competition and upstream innovation: at low levels of competition, market-wide licensing is the optimal and competition reduces innovation, while at high levels of competition targeted licensing is optimal and competition increases innovation. Empirical analysis using a large
panel of U.S. data provides clear support for these predictions linking competition, innovation and licensing.

abstract: PhD


title: An Investigation of Antimicrobial Properties of Grafoid Inc. Graphene Coatings

contributor:
Ramsay, Juliana
Ramsay, Bruce
Chemical Engineering

subject:
Graphene coatings
Antimicrobial properties

abstract:
Graphene materials have been the center of attention due to their physicochemical properties. Moreover, in the past decade, these materials have attracted increasing attention because of their antimicrobial properties. A variety of antimicrobial mechanisms, both physical and chemical have been proposed but they are not clearly elucidated or the evidence in the literature may be contradictory. Graphene materials in this project were provided by Grafoid Inc. as coatings on glass substrates.
These materials were characterized by X-ray photoelectron spectroscopy and Raman spectroscopy to help understand the effects of different preparation methods and coating properties on their antimicrobial properties. Super oxide anion dependent and independent oxidative stress assays revealed that oxidative stress was not a major pathway to cell inactivation after one hour of contact. Three different microorganisms were placed in contact with the graphene coatings to study the effects of type and shape of microorganisms on cell death. Cells in close contact with the graphene surface were killed and coccal-shaped Staphylococcus epidermidis had the highest survival on the coatings regardless of the preparation method, surface coverage, and functionality of the coatings, whereas rod-shaped cells (Escherichia coli and Bacillus subtilis) had higher levels of death, with the Gram negative E. coli usually having a lower level of survival than the Gram positive B. subtilis. Among materials prepared by Method 1, fluorinated reduced graphene oxide coatings had the highest antimicrobial activity, whereas graphene oxide coatings had the lowest antimicrobial activity. Conversely, when (3-aminopropyl) triethoxysilane (APTES) was used in Method 2 to enhance the attachment of graphene coating to the glass surface, then the graphene oxide coatings had the highest and the fluorinated reduced graphene oxide coatings had the lowest antimicrobial activity. E. coli death increased slightly with increasing surface coverage of the coating, regardless of the preparation method and surface functionality of the coating. Contact time between bacterial cells and graphene coatings is also important as rod-shaped cells had almost 100% cell death after three hours of contact with graphene coatings prepared by Method 2.

abstract: M.A.Sc.


title: Examining Nurses’ Perceptions of Hospital Orientations and Their Transition to Practice

contributor:
Luctkar-Flude, Marian
Sears, Kim
Nursing

subject: Orientation Transition Hospital Nurse

abstract:
Background: Annually, new nurses transition from the role of student to registered nurse as they enter the workforce.  These nurses have described feelings of stress and anxiety about ‘absolutely everything’.  To identify and address factors that facilitate and enhance successful transitions into the workforce, it is vital to understand the perceptions of these new nurses during their orientation and transition periods.  While researchers have examined these experiences, previous methodological limitations have left gaps where further analysis is required.
Purpose:  The aim of this study was to describe new nurses’ perceptions of their hospital orientation and subsequent transition in their first two years of practice after graduating from an undergraduate nursing program.
Methods:  Within an interpretive paradigm, a descriptive, exploratory, qualitative methodology was used to conduct semi-structured interviews.  Eight RNs who graduated from an undergraduate nursing program and completed a hospital orientation within the past two years were interviewed using a secure, online video conferencing platform.
Results:  New nurses highlighted the value and importance of the following themes during their orientation and transition into practice: authentic leadership, workplace empowerment, support for professional practice, person-job fit, new graduate support, demographics, psychological capital, and incivility.  New insight into this population showed themes such as the use of technology, physical health, patient impact, and support from family and friends to be important during their orientation and transition.
Conclusions:  The interview discussions were about leaders in healthcare, preceptors, education, well-being, patient safety, and support for practice. These results aid in identifying and addressing some of the shortcomings experienced by new nurses.  This research has significant implications for both nursing education, practice, and future research.  It impacts the undergraduate nursing curriculum with the goal to better prepare nursing students for their transitions into practice. Additionally, conclusions could help to develop more encompassing orientation programs in Canadian hospitals.

abstract: MNSc.


title: The Role of Napping in the Consolidation of Clinically-Relevant Information in Non-Depressed and Depressed Participants

contributor:
Dringenberg, Hans
Psychology

subject:
Sleep
Nap
Depression
Memory
Memory Consolidation
Napping
Cognition

abstract: The hypothesis that sleep may have beneficial effects on memory consolidation has been widely reported for many years (Jenkins & Dallenbach, 1924; Van Ormer, 1933; Fowler, Sullivan, & Ekstrand, 1973). Since then, these findings regarding improved memory retention have also been extended to shorter napping periods (Tucker et al., 2006). Given the memory impairments commonly displayed in individuals with depression (Bearden et al., 2006), this study aimed to explore the impacts of napping on memory consolidation in depressed individuals. Specifically, this study attempted to mimic the educational aspect of cognitive remediation therapy to explore whether napping can be beneficial to memory retention of clinically-relevant information in depressed individuals. To simulate the didactic portion of cognitive remediation, we developed a clinically-relevant memory test using a psychoeducational video that introduces the effects of depression on cognition. Subsequently, we determined whether a napping period can benefit the consolidation of this clinically-relevant material in depressed and non-depressed individuals. We found no differences in memory performance over time between individuals who napped and individuals who stayed awake. However, we did observe associations between several sleep parameters and the degree of memory decay. The findings of this study contribute to the understanding of the relationship between napping and memory consolidation in individuals with depression and may provide a more ecologically valid style of memory testing for future studies.

abstract: M.Sc.


title: The influence of institution accrual on patient survival in Canadian cancer clinical trials

contributor:
O'Callaghan, Chris
Pater, Joe
Richardson, Harriet
Public Health Sciences

subject:
Health Services Research
Cancer
Phase III randomized clinical trials
Institution accrual

abstract:
Purpose: To determine whether participating centre annual accrual and centre-size corrected (“proportional”) accrual are associated with overall survival in Canadian Cancer Trials Group (CCTG) clinical trials.
Methods: The association between centre annual accrual and overall survival was analyzed for all Canadian participants enrolled by 88 member sites onto 52 phase III clinical trials led by CCTG between 1975 and 2013. Centre annual accrual rate per year was used as a continuous variable. 30 member centres in the Province of Ontario with available referral/treatment data were used to determine the association of centre-size corrected accrual with overall survival, where centre size is estimated by the number of treated cases seen at the centre, and centre-size corrected accrual is defined as the proportion of patients treated at a single centre accrued to clinical trials. The association of accrual measures with overall survival was estimated by a hierarchical mixed effects Cox-proportional hazards models.
Results: Median CCTG annual accrual at 88 member centres was 2.47 patients per year (IQR 1.54 – 3.89). Analysis included 20 353 Canadian participants, and 10 338 Ontario participants enrolled onto 52 phase III trials. Centres with higher annual accrual (per 1 patient / year) had longer patient overall survival (HR 0.98, 95% CI 0.96 – 0.99, p = 0.006) after adjustment for covariates. The median centre-size corrected accrual (i.e. as proportion of total incident cases) of Ontario cancer patients that were recruited into CCTG trials, from member centres, was 0.13% (IQR 0.09% – 0.31%). Centre-size corrected accrual (per 0.10% increase in percent of patients accrued to clinical trials) was marginally significantly associated with patient overall survival (HR 0.95, 95% CI 0.89 – 1.02, p = 0.057).
Conclusions:  Overall survival is longer for cancer patients on CCTG trials treated by high-accruing centres. When centre-size corrected (“proportional”) accrual is modelled, the association with patient overall survival is marginally significant.

abstract: M.Sc.


title: The Integration of Virtual Simulation Gaming into Nursing Resuscitation Education: A Pilot Randomised Controlled Trial

subject:
Nursing
Education
Virtual Simulation Gaming
Resuscitation
Deliberate Practice
CAN-Sim
Cardiopulmonary Resuscitation
Advanced Cardiovascular Life Support
Basic Life Support

abstract:
Background
The Heart and Stroke Foundation of Canada (HSFC) reports that up to 40,000 Canadians experience cardiac arrest per year (HSFC, 2016). Of these 40,000, 13.7 to 22.3 per cent achieve return of spontaneous circulation but only 10.5 per cent survive to discharge (Benjamin et al., 2019; Girotra et al., 2012). Global health authorities have set a target of doubling rates of survival from cardiac arrest by 2020 (Diercks, Al-Khatib, & Link, 2016). Meeting this target will rely heavily on well-educated and highly skilled nurses.
Virtual simulation gaming (VSG) is a promising educational tool that helps faculty convey resuscitation education in an engaging and effective way (Borg Sapiano, Sammut, & Trapani, 2018). With the goal of helping students learn how to care for patients in cardiac arrest, a resuscitation-oriented VSG was created. The objective of this thesis was to examine the effect of VSG on nursing students’ during a resuscitation-oriented clinical simulation.
Research Question
In senior-level undergraduate nursing students undergoing resuscitation education, does VSG pre-simulation preparation, when compared to traditional pre-simulation preparation, result in greater student performance during a resuscitation-oriented clinical simulation, as evaluated through the use of a 12-item performance checklist?
Method
Twenty (20) senior-level undergraduate nursing students were recruited to participate in a pilot randomised controlled trial. The trial compared student performance during a resuscitation-oriented clinical simulation. Students were provided either the HSFC’s Basic Life Support (BLS) and Advanced Cardiovascular Life Support (ACLS) guidelines or a resuscitation-oriented VSG in combination with the HSFC’s BLS and ACLS guidelines.
Results
A Mann-Whitney U test reported significantly greater overall performance by the intervention group (Median [Mdn] = 12) than the control group (Mdn = 8) during a resuscitation-oriented clinical simulation, as evaluated through a 12-item performance checklist (U = 12, p = .003).
Conclusion
The results of this work indicate that inclusion of a VSG as an adjunct pre-simulation preparation tool for resuscitation education could have a positive impact on students’ performance during clinical simulation.

abstract: MNSc.


title: Imperceptible Structured Light Projection Mapping for Augmented Reality

contributor:
Greenspan, Michael
Electrical and Computer Engineering

subject:
Structured Light
Projection Mapping
Augmented Reality
Imperceptible Pattern Embedding
Procam
Depth Mapping

abstract:
A novel method is proposed to imperceptibly embed structured light patterns in projected content and decode them to extract a real time range image stream suitable for dynamic projection mapping applications. A commercially available DLP projector is synchronized with camera capture at rates faster than can be perceived. This allows a stream of grey code patterns to be imperceptibly projected and acquired to realize dense, imperceptible, real time, temporally encoded structured light. The method is deployed on a calibrated and stereo rectified procam system to perform depth triangulation from the extracted patterns. The bandwidth achieved imperceptibly is over 6 million points per second using a general
 purpose CPU which is comparable to perceptible commercial hardware accelerated structured light depth cameras.

abstract: M.A.Sc.


title: Towards Improved Process Development for Biolubricant Production from Vegetable Oils

contributor:
Peppley, Brant
McAuley, Kimberley
Chemical Engineering

subject:
Biolubricant
Renewable Hydrocarbon
Vegetable Oil
Kolbe Electrolysis
Electrochemical Decarboxylation
Hydroisomerization

abstract: Biolubricants are lubricants with a base oil produced from biological feedstock. Ester-based biolubricants enjoy the most widespread commercial use, even though complex chemical modifications are required to improve their physicochemical properties. Renewable-hydrocarbon biolubricants can be more attractive because they possess desirable qualities such as superior cold-flow properties and oxidative and hydrolytic stability. In addition, hydrocarbon-based biolubricants are more similar to conventional lubricants and can be easily substituted using existing infrastructure and lubricant formulations. Current research on renewable hydrocarbons is heavily focused on hydrodeoxygenation of vegetable oils involving operating conditions in excess of 50 bar and 450 °C. Alternative routes such as those involving electrochemical decarboxylation through Kolbe electrolysis (KE) benefit from milder conditions and consume less hydrogen overall. A further benefit of Kolbe electrolysis is the potential for integration into renewable energy systems. The biolubricant production process using KE requires a hydrogenation pre-treatment stage and a hydroisomerization (HI) post-treatment stage. Theoretically, this process can be improved by combining both stages into a single pre-treatment HI. Experiments performed using HI of fatty acids have shown difficulty in converting oleic acid to isostearic acid. Key issues include the occurrence of hydrogenation without isomerization and a loss of carboxyl groups during isomerization. A factorial experimental design was used to determine how factors such as temperature and pressure might influence the isomerization process. Additionally, several experiments were performed to test the hypothesis that lactones can be converted via hydrogenation into carboxyl groups. Results indicate that temperature is a highly significant parameter in the isomerization process and that higher temperatures are beneficial for the production of branched compounds. Unfortunately, the production of branched compounds is accompanied by a loss of carboxyl groups. Lactone hydrogenation experiments were unsuccessful in restoring carboxyl functionality. It is possible that a different catalyst than platinum on alumina is required for the hydrogenation of lactones. Another possibility is that lactone formation is a minor contributor to the loss of carboxyls and the main cause for the loss is an irreversible deoxygenation reaction.

abstract: M.Sc.


title: Learning with psychosis: A narrative inquiry exploring the lived experiences of secondary students living with early psychosis

contributor:
Bolden, Benjamin
Education

subject:
Early Psychosis
Student Experience
Mental Health
Inclusive Education
Empowerment Theory
Narrative Inquiry

abstract: Those who experience psychosis struggle to find inclusion within educational institutions (Goulding, Chien, & Compton, 2010; Laurence, Rosseau, Foriter, & Mottard, 2016; Morgan et al., 2012) despite a growing recognition of the need to create an equitable environment for students with mental health difficulties. This research explores the complexities of the experiences of students with psychosis in the secondary school environment with a view to improving support for these individuals. The research focused on each student’s unique experiences by using an empowerment and narrative inquiry design. I recruited a small sample of three primary participants from an early psychosis intervention program located in an Ontario community. Data were collected through in-depth semi-structured one-on-one interviews and analyzed with narrative processes. My findings are presented through retelling the story of each participant’s high school experiences, and highlighting their perceptions of inclusion and support. Key findings in Mary, Angel, and Isaac’s stories describe: (a) typical high school experiences, external challenges, academic challenges, and social challenges; (b) sense of belonging, community participation, social inclusion at school, and the challenges that impacted how participants were included at school; and (c) feelings of support, environmental supports, supportive people, supportive actions, and the challenges that impacted support at school. Reading the stories of these students will provide teachers, administrators and policy makers with insight into the unique experiences of students who live with early psychosis. My aim is that this insight will contribute to a more inclusive discussion about mental health in education, informed by the voices of students who have experienced psychosis.

abstract: M.Ed.


title: Simultaneous Topology and Build Orientation Optimization for Minimization of Additive Manufacturing Cost and Time

contributor:
Kim, Il Yong
Mechanical and Materials Engineering

subject:
Topology Optimization
Additive Manufacturing
Build Orientation Optimization
Density Gradient
Support Material
Manufacturing Constraints

abstract:
The ever-present demand for increased performance in mechanical systems, with reduced cost and manufacturing time, has led to the adoption of computational design tools and innovative manufacturing methods. Among these tools is topology optimization, which typically produces highly complex designs that can be prohibitively difficult to manufacture. However, recent developments in additive manufacturing provide the means to manufacture such designs, including components suitable for service in industrial and commercial applications. Integration of these two technologies has the potential to reveal further benefits and innovate the design and manufacture of mechanical components.
This work presents a novel mathematical methodology for simultaneous build orientation and topology optimization, which considers additive manufacturing cost and time, and structural compliance. Various physical factors that influence additive manufacturing cost and time were researched, with component surface area and support volume implemented as contributors in this work. The presented methodology approximates support volume throughout topology optimization with variable build orientation; a critical ability, as support volume is highly dependent on both part topology and build orientation. This enables direct minimization of support volume in simultaneous density-based topology and build orientation optimization; an area that was previously unaddressed in literature. Sensitivity expressions were derived for the continuous and differentiable methodology, thereby permitting the use of efficient gradient-based optimization solvers. Three numerical examples are provided that demonstrate the proposed methodology is capable of efficiently identifying optimum build orientations, while performing the simultaneous optimization. Evaluation of the support volume and build time required to manufacture the optimization results, using commercial additive manufacturing software, demonstrated the ability of the optimization to reduce additive manufacturing cost and time. The simultaneous optimization performed in these examples produced a range of designs with equivalent performance to designs produced by multi-objective topology optimization performed at a fixed optimal orientation.

abstract: M.A.Sc.


title: Teachers in the Trenches: Exploring Canadian-Certified Early-Career Teachers' Experiences of Turnover and Retention in International Schools in China

contributor:
Kutsyuruba, Benjamin
Education

subject:
teacher turnover
teacher retention
international schools
China
early-career teachers
Canadian-certified teachers

abstract:
Teacher turnover, often referred to as teacher attrition or migration, has been a growing worldwide concern for many years, particularly for teachers within their first five years of the teaching profession. Multiple studies have been conducted that identify the causes of teacher turnover and the possible teacher retention strategies within schools that can reduce the impact of this problem. Despite having knowledge of the factors that cause teacher turnover and the potential solutions for teacher retention, much of the research available on teacher turnover is both US-based and quantitative in nature, and as a result the unique and descriptive accounts of the human voices that experience the issue are often underrepresented from outside North America.
Inspired by my own experiences while working in an international school, this phenomenological study was conducted with the purpose of discovering and exploring the unique experiences of Canadian-certified early-career teachers surrounding the challenges, barriers and supports connected to teacher turnover and retention decisions in international secondary schools that use a Canadian curriculum in China. In order to carry out this study, a combination of a survey and individual interviews was used. Surveys were analyzed descriptively while interview data were audio recorded, transcribed verbatim and analyzed using a general inductive approach.
The findings of this study suggest that turnover and retention decisions in China are highly individualistic in nature and depend on a multitude of different contextual and individual factors. However, five main themes emerged from participants’ accounts which were influential in turnover and retention decisions. They included: participants motivations for working in China; barriers that influence turnover decisions; existing supports to overcome turnover challenges; supports teachers feel would be beneficial to enhance retention decisions; and, advice from teachers to teachers. By exploring these themes, a more comprehensive understanding of beginning teachers’ perceptions and experiences surrounding the phenomenon of turnover and retention decisions in international schools in China emerged. Moreover, the importance of supporting early-career teachers both individually and professionally during the transition period into the teaching profession was highlighted throughout this study.

abstract: M.Ed.


title: A Three-Dimensional Experimental and Numerical Study of Nearshore Hydrodynamics and Morphology Change on a Steep Sand Beach

contributor:
Mulligan, Ryan
Civil Engineering

subject:
Coastal Engineering
Physical Modelling
Steep Beach

abstract:
Storm waves breaking on steeply-sloping sand beaches can generate strong currents across a narrow surf zone, and experience different rates of sediment transport and morphodynamic change compared to
beaches with milder slopes. To investigate the dynamics on this type of beach, a three-dimensional
physical model is implemented in a wave basin and a long steeply-sloping sandy beach is exposed to a
series of different conditions generated by a paddle. Three different experiments are performed to observe
the nearshore responses to surface waves.
A momentum balance approach is applied to the nearshore hydrodynamics inside and outside the surf
zone to investigate the transfer of wave momentum to the alongshore flow. This approach reveals that
radiation stress gradients and cross-shore advection terms are dominant in the shoaling region. In the breaking region, the momentum exchange is mainly governed by the radiation stress gradients with a
smaller contribution from cross-shore advection that relatively balances with the bottom friction and
horizontal mixing terms.
To investigate the beach morphology change, topographic surveys of a beach-dune system are performed and related to changes in wave energy during a storm. The results indicate that a near-vertical beach scarp forms, retreats landward, and then becomes controlled by the nearshore beach slope. Sediment eroded to form the scarp is initially deposited at the dune toe, however, as wave energy increases sand is transported by the alongshore current and is deposited in the nearshore zone increasing the surf zone width.
A non-hydrostatic phase-resolving numerical model is used to investigate the wave-driven hydrodynamics that correspond to observed beach morphology changes during a storm. The numerical results indicate that the alongshore current is generated by wave breaking in the nearshore zone and it
increases in magnitude across a widening surf zone for increasing wave energy. This is associated with a
bottom shear stress that exceeds the critical bed shear stress, with the potential to initiate motion and
transport sediment in agreement with the experimental observations. Overall, the results of this thesis provide insight into the coupled interaction between the three-dimensional wave-driven hydrodynamics and morphologic evolution of a steep sandy beach.

abstract: PhD


title: Childhood Maltreatment and Adulthood Depression Severity: Using Structural Equation Modelling to Uncover Maltreatment-Symptom Specificity

contributor:
Harkness, Kate
Psychology

subject:
Childhood Maltreatment
Depression
Symptom Specificity
Factor Analysis
Structural Equation Modelling

abstract: Major depressive disorder (MDD) is highly heterogeneous in its etiology, symptom presentation, course, and treatment response. Despite knowing this for decades, however, clinicians and researchers have generally treated MDD as homogenous by relying on total symptom severity scores and linking them to broadly defined etiological factors (e.g. childhood adversity). To truly understand the complex associations between MDD etiology and symptom presentation, general etiological factors need to be deconstructed into their distinct components and independently linked to individual symptom dimensions of MDD. This thesis project aimed to untangle heterogeneity in MDD etiology and symptom presentation by investigating symptom dimensions uniquely associated with childhood emotional, physical and sexual maltreatment. MDD symptom dimensions were identified with exploratory factor analysis (EFA) of Hamilton Rating Scale for Depression (HRSD) responses, using three archival datasets covering 243 community-sampled depressed participants. The data-driven measurement model of the HRSD was evaluated using confirmatory factor analysis (CFA) alongside a four-factor model taken from a previous meta-analysis of HRSD factor structure. Using structural equation modelling (SEM), associations were estimated between HRSD factors and childhood maltreatment (CM) variables from the Childhood Experience of Care and Abuse (CECA) retrospective clinical interview. A five-factor measurement model of the HRSD was identified, which statistically outperformed the four-factor theoretical model. No structural models were formally retained due to poor model fit with the sample data, meaning that the CM-MDD associations observed in this investigation were inconclusive. Although inconclusive, these results suggested that MDD symptom specificity does vary across the different CM types and that some MDD symptoms are associated more strongly with certain CM types than others. Initial evidence suggests that all symptoms captured by the HRSD are more severe in individuals with a history of sexual maltreatment, that anxiety and anhedonia-like symptoms are worse in individuals with a history of physical maltreatment, and that core depression symptoms are worse in individuals with a history of emotional maltreatment. To determine which of these specific associations generalize beyond the current sample, however, this SEM analysis must be cross-validated with an additional sample of community-residing depressed individuals.

abstract: M.Sc.


title: Characterizing Statistical Learning of Music

contributor:
Cuddy, Lola Dr.
Troje, Nikolaus Dr.
Psychology

subject:
statistical learning
music perception
EEG

abstract:
Understanding how we gain representations of music is crucial for a comprehensive understanding of music perception. Several studies suggest that listeners extract statistical regularities in music via passive exposure, i.e., statistical learning. Statistical learning could thus underlie our ability to learn about unfamiliar music. While research shows that musical short-term knowledge can be gained via this process, it remains unclear whether longer lasting knowledge can be gained this way. This thesis aims to address this issue.
In Study 1, participants gave probe-tone ratings before and after exposure to an artificial music genre defined by its tone distribution.  Participants’ responses to these tones revealed that  they are sensitive to both the tone distribution of the preceding tone sequence and tone distributions encountered earlier in the experiment. This suggests that musical knowledge can be gained via statistical learning over and above short-term knowledge. Participants also distinguished the exposed music genre from another artificial genre after exposure. In Study 2a, I ascertain that this result is not due to prior familiarity with one of the artificial music genres. In Studies 2b and 2c, I show that participants can differentiate the two music genres based on pitch cues.
In Studies 3a and 3b, I compared participants’ brain activity following congruent and incongruent tones to familiar or unfamiliar tone distributions using EEG. Activity at frontal electrodes from 380 to 450 ms post stimulus onset was larger for incongruent probe tones, but only when the preceding probe-tone context was based on the familiar tone distribution. This event-related potential can be considered an index of musical long-term knowledge because behavioral results suggest that participants were influenced not just by short-term knowledge when presented with familiar tone distribution probe-tone contexts. In Study 4, participants completed Study 1’s paradigm. Key behavioral results from Study 1 were replicated. Further, EEG data suggest that musical long-term knowledge may form simply through encountering an unfamiliar music genre in short tone sequences, without extended exposure.
These findings are discussed regarding their implications for the statistical learning of music, the influence of music training, and the field of statistical learning research in general.

abstract: PhD


title: Mobilization of Non-aqueous Phase Liquid by Flowing Gas Bubbles in Porous Media

contributor:
Mumford, Kevin
Civil Engineering

subject:
Ebullition
NAPL mobilization
Contaminated sediments
Trapped residual NAPL
NAPL spreading
Oil sheen

abstract: Gas bubbles can significantly affect contaminant transport in both sediments and groundwater systems. In some circumstances, gas bubble mobilization can result in the transport of non-aqueous phase liquids (NAPLs) as coatings or films on the gas bubble surface, which could move a greater mass of volatile organic compounds (VOCs) through a porous medium than what might be transported as volatized, gas-phase mass. Despite this potential enhanced transport, whose outcomes include the appearance of oil sheens created as gas bubbles break at the water surface after being transported out of contaminated sediments, there has been little controlled laboratory study to determine factors that may control bubble-facilitated NAPL transport in porous media. Laboratory experiments conducted in thin, two-dimensional flow cells packed with medium sand showed that both trapped LNAPL (heptane, decane, soltrol 100) and DNAPL (creosote) could be mobilized when subjected to gas flow. In these experiments, LNAPL mobilization originated from the top of the source zone and moved along the gas flow pathway as a clearly visible finger (as high as 11.3 cm). When the emplaced upper sand layer was too thin (5.4 cm), the breakthrough of this LNAPL finger occurred, resulting in contamination of the clean water above the sand. LNAPL fingers occurred predominantly during relaxation and gas redistribution (slow discontinuous gas flow) after air injection was stopped in the 10 mL/min experiments. Observed pore-scale double displacements were considered as the main reason for the LNAPL finger development. In comparison, creosote was mobilized as either thin films on the bubble surface or tails below the bubbles. Petroleum hydrocarbon (PHC) concentrations measured above the clean sand indicated that creosote was constantly released out of the sand pack over 8 hours in the short-term experiments, with more mass being released through thinner and finer sand layers. In the long-term experiment, clearly visible evidence suggested significant depletion (~69%) of the DNAPL source zone after 30 days of gas injection. The similar ratios of PAHs in the transported and original source creosote confirmed the stable transport of creosote as a whole in the sand layer without breakdown rather than by mass transfer to the gas bubbles.

abstract: M.A.Sc.


title: Development and Psychometric Evaluation of the Post-Secondary Student Stressors Index

contributor:
Stuart, Heather
Public Health Sciences

subject:
post-secondary
stress
scale development
psychometric analysis
psychiatric epidemiology
mixed methods research

abstract:
Background:
Over the past several years, reports of excessive stress and symptoms of languishing mental health have been increasingly reported among samples of Canadian post-secondary students. Chronic stress is highly correlated with negative mental health outcomes and formal diagnoses for common mental illnesses, such as depression and anxiety, have continued to climb. The purpose of this doctoral research program was to develop a new instrument to better assess the sources of post-secondary student stress. Existing instruments in this area are imperfect for a number of reasons, including weak (or lack of) psychometric analyses, poorly focused scope, and outdatedness. Importantly, few existing tools have involved students in the process of development.

Methods:
The development of the Post-Secondary Student Stressors Index (PSSI) spanned two years, and involved students as collaborators and subject matter experts over the course of the project. The instrument was designed to identify stressors specific to the post-secondary setting, with the aim of providing post-secondary institutions with a tool to identify the most significant sources of stress for students on their campuses. To facilitate item pool development, students participated in online surveys and focus group discussions. The initial item pool, derived from these qualitative responses, was then refined through the use of individual cognitive interviews and an online Delphi method. Finally, an online pilot test was conducted to assess psychometric properties.

Results:
The PSSI is composed of 46 stressors across five domains: academics, learning environment, campus culture, interpersonal, and personal. Students were asked to rate each stressor by severity and frequency. The tool demonstrated strong psychometric properties, with four types of validation evidence collected to support its validity: content, response processes, internal construct (including test-retest reliability), and relations to other variables.

Conclusion:
Our exploratory sequential mixed methods research design allowed for the development of a heavily context-based tool demonstrating strong psychometric properties. The PSSI can provide Canadian post-secondary institution administrators, student wellness staff, and program developers with a valid method of identifying the sources of student stress on their campus, and facilitate better targeting of mental health promotion and mental illness prevention efforts to best support students’ needs.

abstract: PhD


title: Scalar Quantization Algorithms for the Robust Transmission of Correlated Sources Over One- and Two-Way Channels

contributor:
Chan, Wai-Yip Geoffrey
Alajaji, Fady
Electrical and Computer Engineering

subject:
Two-way channel
uncoded transmission
lossy joint source-channel coding
correlated Gaussian sources
scalar quantization

abstract:
The problem of lossy transmission of correlated sources over discrete two-way channels (TWCs) is considered. The objective is to develop a robust low delay and low complexity source-channel coding scheme without using error correction. A simple full-duplex channel optimized scalar quantization (COSQ) scheme that implicitly mitigates TWC interference is designed. Numerical results for sending Gaussian bivariate sources over binary additive-noise TWCs with either additive or multiplicative user interference show that, in terms of signal-to-distortion ratio performance, the proposed full-duplex COSQ scheme compares favourably with half-duplex COSQ. Moreover, our numerical results illustrate that one can achieve significant gain when the proposed two-user COSQ is optimally designed for a discrete TWC with additive Markov noise compared to the case when the TWC is fully interleaved. Furthermore, it is demonstrated that correlation between sources can be useful in order to reduce quantization distortion and boost the decoders' reconstruction reliability.

Also, we investigated the effects of feedback in the design of a COSQ over a discrete one-way channel with additive Markov noise by proposing an adaptive COSQ (ACOSQ) where the channel input sequence are adaptively generated based on the received symbols over the feedback link. Numerical results indicate that one can achieve a lower overall distortion by employing feedback in the design of a quantizer for a noisy channel compared to the case where feedback information is not available. Similar to our proposed two-user COSQ, our numerical results demonstrate that one can obtain significant improvement in terms of signal-to-distortion ratio when the ACOSQ scheme is optimally designed for a discrete one-way channel with memory compared to the case where channel is rendered memoryless by interleaving.

abstract: M.A.Sc.


title: Driver Behavior Modelling and Risk Profiling Using Large-Scale Naturalistic Driving Data

contributor:
Hassanein, Hossam
Abu-Ali, Najah
Electrical and Computer Engineering

subject:
Driver profiling
Behavior modelling
Driving risk prediction
Route planning
Hidden Markov Models
Intelligent transportation systems

abstract:
Driver risk profiling is an emerging scheme in the field of Intelligent Transportation Systems (ITS). Conventionally, a risk score of a driver is calculated on a per-trip basis according to the number of harsh braking, hard cornering, aggressive acceleration, and excessive speeding events. Risk scoring in the academic literature and industry has two main limitations. First, risk scoring has been primitively performed based on a pre-assumption on the risk weights of driving behaviors. Second, the conventional method of risk scoring ignores the individual differences between drivers and the variation in their skillfulness levels.

In this thesis, we tackle the first limitation through the utilization of the Strategic Highway Research Program 2 (SHRP2) large-scale Naturalistic Driving Study (NDS) dataset (i.e., the largest of its kind to date) and performed by Virginia Tech Transportation Institute (VTTI) to develop reliable and robust risk scoring functions. We first utilize the behavioral information of more than 3,000 drivers during crash, near-crash and normal driving events to develop a robust machine learning model that is able to predict the driving risk quantified in terms of crash and near-crash events of drivers given their long-term behavioral patterns. A complete driver profiling framework that considers the joint effect of driving behaviors and environment conditions on driving risk is then proposed and validated. Validation results indicate the robustness of the developed models and framework. Then, a novel safety-based route planner that utilizes the personalized risk profiles of drivers in suggesting individualized routing options is proposed and analysed through a real-world case study that highlights the significance of the proposed route planner.

To tackle the second limitation, we propose a fault inference profiling system in which drivers are profiled based on their individual risk rate. Following the detection of risky events, proposed system can infer the fault contribution of drivers using the time-series radar and vehicular data prior and after risky events. Fault inference is performed through training five customized Hidden Markov Models (HMMs), each representing a behavioral class, on 248 risky events. Promising classification results are obtained and discussed.

abstract: PhD


title: The Role of Municipal Level Government in Accelerating 100% Renewable Energy Use: a Case Study of Oxford County, Ontario

contributor:
Whitelaw, Graham
Geography and Planning

rights: Attribution-NonCommercial 3.0 United States

subject:
Renewable
100% Renewable Energy
Planning
Urban Planning
Land Use
Land Use Planning
Engagement
Public Engagement
Step Code
Oxford County
Ontario
Tiering
Sustainability
Rural
Nelson BC
Canada
Case Study
Triangulation
Carbon Neutral
Sweden
Renewable Energy
Solar
Photovoltaic
Wind Turbine
Stakeholder
Local Government
Denmark
Germany
Freiberg

abstract: Climate change will have severe impacts on the biosphere that human society depends on, with repercussions increasing in step with the quantity of greenhouse gases emitted into the atmosphere. These impacts can be avoided by drastically reducing emissions from human society by transitioning to a 100% renewable energy system (100% RE) and reducing the quantity of energy needed overall. In 2016 Oxford County, Ontario set a goal to reach 100% RE by 2050. Using Oxford as a case study, this thesis describes best practices for transitioning to 100% RE for local governments in Canada. This thesis identifies the current progress toward reaching 100% renewable energy in Oxford County and existing strategic gaps that need to be addressed to achieve their goal of 100% RE by 2050 at the community level. It also sets out best practices and recommendations for future research in regards to achieving 100% RE in municipalities across Canada. This thesis also extends thinking on conceptual and theoretical approaches to achieving 100% RE in particular relation to municipal land use planning. The methods used in this analysis are based on the constant comparative method, utilizing a triangulation of (a) literature, (b) policy documents and (c) interviews with 17 expert informants from Canada and abroad. The value of communicative planning, planning tools and the various roles of planners are defined in the context of contributing to a 100% RE transition. Oxford County’s energy and land use planning policies were reviewed and compared against those of other jurisdictions. Engagement, dwelling density, mixed use development, energy mapping, building retrofits and energy efficient building codes can all serve as effective tools to reduce GHG emissions when properly utilized. Oxford County has laid the ground work for a 100% RE future, though much work will need to be done to help it reach this ambitious goal. The policies of other jurisdictions provide some guidance. Over the past decade, the concept of utilizing land use planning to develop low GHG emission communities has become part of mainstream discourse. More recently, plans to reach 100% RE at the community level have become a globally phenomenon. This research is part of an emerging trend in research and policy, recognizing land use planning as an integral part of 100% RE Plans.

abstract: M.PL.


title: Household Return Heterogeneity in the United States

contributor:
Smith, Gregor
Abbott, Brant
Economics

subject:
Returns on Wealth
Heterogeneity

abstract: This thesis provides empirical evidence on heterogeneity in returns on wealth among U.S. households. Chapter 1 provides a summary of how return heterogeneity has been theoretically and quantitatively shown to be necessary in explaining wealth inequality. It discusses the limited empirical evidence driven primarily by a lack of adequate panel data on household returns. Chapter 2 presents a new method to construct panel data on household-level rates of return in the United States using the newly revised Panel Study of Income and Dynamics (PSID) data. Returns are calculated for total household assets and wealth as well as within five asset classes. This panel data provides the first return measure for the total household portfolio, and it is the first to include net investment in the measure of capital gains. Empirical evidence is documented on the degree of return and risk-adjusted return heterogeneity and returns' correlation with wages. Chapter 3 uses fixed effects with empirical Bayes shrinkage to document permanent heterogeneity in returns across households, even within asset classes. The majority of the permanent heterogeneity in the returns to wealth are driven by heterogeneity in the degree and cost of borrowing. Permanent heterogeneity in leverage across households is also documented. Evidence is provided on how returns differ across the wealth distribution. Chapter 4 documents the degree of idiosyncratic asset return risk, its serial correlation, and its correlation with wage risk. Sizeable transitory idiosyncratic return risk is documented for total household assets and for returns within each asset class. Idiosyncratic shocks to wages are found to be correlated with idiosyncratic shocks to returns in specific asset classes. Return and wage risk correlation and return serial correlation are found to depend on a household's age and homeownership. By providing a new source for panel data on rates of return, this thesis presents the first empirical evidence on the nature and degree of return heterogeneity in the United States. Chapter 5 summarizes the empirical evidence. It highlights the implications for the literature on portfolio choice and for the structure and calibration of return heterogeneity in quantitative models to study wealth and income inequality.

abstract: PhD


title: A Stepwise Approach to Verification of the Combined Finite-Discrete Element Method for Modelling Instability Around Tunnels in Brittle Rock

contributor: Geological Sciences and Geological Engineering

subject:
Stepwise Verification
Finite-Discrete Element Method
Finite Element Method
Tunnel
Numerical Modelling
Tunnelling
Hard Rock
Hybrid Numerical Model
Geomechanics
Rock Mechanics
Pseudo-Discontinuum
Voronoi
Brittle Rock

abstract:
Numerical modelling of excavations in rock has advanced considerably in recent decades. While continuum numerical models form their basis in methods which can be verified by analytical solutions, discontinuum and hybrid numerical modelling software are challenging to verify. This necessitates the development of processes that can verify individual aspects of complex models. The combined finitediscrete element method (FDEM) allows for the numerical representation of progressive fracture in a simulated elastic material. The FDEM is a powerful tool for modelling instability around tunnels in brittle rock; however, significant verification of the method is required for its use in predictive modelling in critical engineering projects. To verify the FDEM for the purpose of modelling instability around tunnels in brittle rock, a multi-method and multi-scale stepwise verification approach is proposed.
Multi-scale verification is required due to the practical limitations of current computational power. Simulation of a laboratory scale tests generally requires a mesh size not significantly larger than the median grain size of the material, limiting the size of elements to a few millimeters for most rock types. In tunnel scale models, a larger element sizes must be used. To relate the input parameters obtained from the laboratory scale calibration to parameters which can be used in tunnel-scale modelling, a gradual upscaling process for Unconfined Compressive Strength (UCS) test simulations is developed. The results of the upscaling process provide guidance for input parameter selection for tunnel-scale models,  and insight into scale effects in FDEM models.
In multi-method verification, equivalent modelling scenarios are represented using analytical and numerical methods of increasing complexity, to allow individual model behaviours to be progressively verified. A pseudo-discontinuum finite element method (FEM) approach is compared with the FDEM for modelling fracture propagation. Agreement of results is found for simulated non-frictional materials; however, for frictional materials, results agreement is not achieved. Further assessment of tunnel model response to pseudo-discontinuum FEM and FDEM input parameters will lead to improvement of input parameter and result equivalency between methods.

abstract: M.A.Sc.


title: Investigating Chronic Pain Management Among Emerging Adults

contributor:
Goldie, Catherine
Nursing

subject:
chronic pain
pain management
emerging adults

abstract:
Background: Emerging adulthood is the age between late teens into mid to late 20s. This transition is characterized by a lack of role permanence, where self-reliance and independence are sought. During this period, emerging adults with chronic pain struggle with achieving age-specific expectations while dealing with physical limitations imposed by their pain. Although frequently viewed as synonymous with the general adult population (ages 18-64), well documented differences including unstable societal roles and identity have been acknowledged in this group. This quantitative study is a descriptive analysis of demographic, pain characteristics, and management interventions of emerging adults accessing chronic pain care, an important first step in the inquiry process.
Methods: Using retrospective chart review over a six-month period, 41 emerging adults (aged 18-29) and 41 middle aged adults (aged 30-64) receiving care from a chronic pain clinic in Southeastern Ontario were examined. Groups were matched based on sex and number of pain sites. Demographic and pain characteristics (severity, interference, self-efficacy, depressive symptoms, and catastrophizing), interventions, referrals, and clinic utilization were described. Group differences were examined using descriptive and multivariate analysis.
Results: The emerging adult group were mostly female (66%) and the majority reported two or more pain sites (80%). While demographic, pain characteristics, and pharmacological and non-pharmacological interventions were similar between groups, pain severity differed, t(80) = -2.15, p = 0.035, with middle aged adults reporting higher scores. Emerging adults more frequently received referrals for additional consultation and/or diagnostic investigations, compared to middle aged adults (X2 (1, N = 82) = 4.97, p = 0.026). Moreover, the number of psychology visits was significantly different between groups (X2 (1, N = 82) = 7.29, p = 0.007), with more emerging adults having at least one visit. When investigated using multivariate analysis, emerging adults with higher patient health questionnaire scores were more likely to see a psychologist (OR 1.23, 95% CI 1.014-1.492).
Conclusion: Findings of this study inform our understanding of emerging adults who utilize chronic pain services. Further research is needed to better understand the efficacy of treatments offered and if current pain management approaches are meeting the needs of this population.

abstract: MNSc.


title: Evaluation of the hemostatic stress response in Type 1 von Willebrand Disease

contributor:
James, Paula
Pathology and Molecular Medicine

subject:
von Willebrand Disease
von Willebrand Factor
Hemostatic stress response
Hemostasis
Desmopressin
Endothelial colony-forming cells
Bleeding Score
Bleeding

abstract:
Type 1 von Willebrand Disease (VWD) is an inherited bleeding disorder resulting from a quantitative deficiency in the procoagulant protein von Willebrand factor (VWF). Diagnosis is dependent on a reduction in VWF levels and the identification of an abnormal bleeding history. However, diagnosis and management of this condition are challenging due to the significant heterogeneity reported in bleeding symptoms and the absence of a correlation between circulating VWF levels and bleeding severity. The ability to increase VWF levels in response to hemostatic stress (i.e. vascular injury) is important in managing bleeding. To date, this ability, referred to as the hemostatic stress response, has not been prospectively evaluated as a disease modifier of the bleeding symptoms seen in Type 1 VWD. Desmopressin, used therapeutically, can also be used as a hemostatic stress surrogate, as can exercise, to study the response to injury. By performing desmopressin trials over two consecutive days, the response to repeated stress can be evaluated. The hemostatic stress response can also be characterized by studying subject-derived endothelial colony-forming cells (ECFCs). We aim to show that a decreased and less sustained rise in VWF in response to hemostatic stress surrogates contributes to a more severe bleeding phenotype in individuals with Type 1 VWD.
This thesis demonstrated that Type 1 VWD individuals have a decreased and less sustained rise in VWF in response to hemostatic stress surrogates compared to controls. We demonstrated that the differences in VWF and FVIII levels between Type 1 VWD and control groups increases in response to desmopressin and that this increased difference was maintained for at least twenty-four hours. Further, Type 1 VWD participants exhibited indicators of increased clearance and decreased synthesis of VWF. Overall, we demonstrated that the decreased response is correlated with increased bleeding. ECFCs isolated from these participants were further characterized for VWF expression and secretion demonstrating that the hemostatic stress response may be modelled ex vivo.
	In conclusion, these data may be used to provide clinicians with a better understanding of the determinants of bleeding in Type 1 VWD and allow for better risk stratification in this patient population.

abstract: M.Sc.


title: Motor Memories in Manipulation Tasks are Linked to Contact Events Between Objects

contributor:
Flanagan, Randall
Gallivan, Jason
Neuroscience Studies

subject:
Motor Control
Sensorimotor Learning
Object Manipulation
Motor Memory
Control Points

abstract: Humans have the remarkable ability to learn and perform motor skills, often involving the manipulation of different objects or tools, such as swinging a hammer or a tennis racket. The objects that we manipulate are usually associated with different dynamics, which determine the movement of an object as a result of the force applied. Skillful manipulation requires forming and recalling memories of these object dynamics. Although it has been assumed that such memories are linked to objects, per se, it was recently shown that people can form separate memories, for opposing dynamics, when these are linked to different locations, or ‘control points’, on an object (Heald, Ingram, Flanagan, & Wolpert, 2018). In the previous study, participants controlled the handle of a robotic device to move a virtual rectangular object with circles (control points) on the left and right sides. In different trials, they were instructed to move either the left or right control point to different targets. When these control points were paired with opposing force fields, adaptation was observed even though the required movement was constant, a situation that typically cannot be learned. In this previous study, both the controlled point and the target location changed between contexts. The aim of the current study was to assess whether one or both of these factors is critical for learning. The first experiment was similar to our previous study, except that the bar automatically rotated as it was moved forward such that the left and right control points, controlled in different contexts, moved to a common target. In the second experiment, the bar was aligned vertically with a single control point at the far end. Again, the bar rotated as it was moved forward such that the control point moved to a target located on either the left or right in different contexts. We found that, in both experiments, participants learned opposing force fields applied in the two contexts. We conclude that separate memories of dynamics can be formed for different ‘contact events’ involving a unique combination of the controlled point on the manipulated object and the target object this point contacts.

abstract: M.Sc.


title: Witnessing Public Drinking and its Relevance to Discrimination Against Individuals Living With Alcohol Use Disorders

subject:
Public drinking
Discrimination
Alcohol Use Disorders
Stigma
heavy drinker
World Value Survey
direct contact

abstract:
Objective: The primary goal of this study was to determine if a relationship existed between how often a person perceives public drinking in their neighbourhood and if they discriminate against individuals living with alcohol use disorders. The second study goal was to identify if the prevalence of heavy episodic drinking among drinkers in a country modified this relationship. Methods: Our secondary analysis used publicly available data from the World Value Survey Wave 6, in addition to the Global Status Report on Alcohol and Health 2014 provided by the World Health Organization. To investigate the relationships of interest, a two-level multivariate hierarchal logistic regression model with random intercept was created. Prevalence of heavy episodic drinking among drinkers in a country was categorized into quartiles of approximately equal size. Several sensitivity analyses were used to investigate country-specific relationships and the effects of missing data.
Results: While the prevalence of heavy episodic drinking among drinkers in a country did modify the relationship, there was no dose response. All of the significant relationships were found within the relative low category of heavy episodic drinking prevalence among drinkers. Additionally, when missing data was accounted for, only one significant relationship remained. When a single level model was created to examine the relationship between perceived frequency of neighbourhood public drinking and discrimination against individuals living with alcohol use disorder within individual countries, unique relationships were found within each country. Conclusion: Although prevalence of heavy episodic drinking among drinkers appeared to be largely unrelated to the main relationship between the perceived frequency of neighbourhood public drinking and discrimination against individuals living with alcohol use disorders, it was clear that the main relationship does exist within certain countries. These results aim to inspire future studies to identify a link between direct contact, second-hand alcohol harms, and how these harmful encounters may motivate discrimination against individuals living with alcohol use disorders within specific cultural contexts.

abstract: M.Sc.


title: Electrical Double Layer in Polar and Nonpolar Media in the Presence of Surfactants

contributor:
Barz, Dominik P. J.
Chemical Engineering

subject: Electrical Double Layer (EDL)

subject: Electrical Impedance Spectroscopy (EIS)

subject: Dielectric Relaxation Spectroscopy (DRS)

subject: Permittivity

subject: Zeta Potential

subject: Surfactants

subject: Micelles

abstract: The objective of this thesis is to improve our understanding of the concept of electrical double layer (EDL). The EDL is the basis of all electrokinetic phenomena. Despite numerous studies in the span of over a century, our perception of this concept is far from complete owing to its complex nature. In this work, we revisit the structure and properties of EDL in polar and nonpolar media. First, we investigate the change of the zeta potential of a representative polymeric particle in the presence of various types of surfactants using electrophoretic light scattering. This study allows us to comprehend the tuning of the zeta potential of a polymeric substrate as well as the adsorption mechanisms of the different types of surfactants. Second, we use dielectric relaxation spectroscopy (DRS) to understand the EDL formation around the micelles in an aqueous medium. This method can be implemented for determining the surface conductivity as well as the zeta potential of the dispersed species in an opaque sample. Third, electrical impedance spectroscopy (EIS) is used to resolve the structure of an EDL in aqueous electrolyte and surfactant solutions. This study allows us to infer the dominance of the compact layer in determining the equivalent capacitance of the EDL as well as the change in the permittivity of the medium within this compact layer. Finally, the EIS measurements are also conducted in a nonpolar medium in the presence of a nonionic surfactant. The electric charge formation and the emergence of the EDL are explored and compared to the charge formation mechanisms proposed in the literature.

abstract: PhD


contributor:
Brison, Jeff
Cultural Studies

subject:
Tattooing
Tattoo
Tattoos
Tattoo Artist
Tattooist
Tattooer
Canadian Tattooing
Canadian Art History
Canadian History
Canadian Studies
History
Art History
Work
Professional
Professionalization
Visual Culture
Visual Studies
Cultural Studies
Cultural History
Social History
Cultural Production

abstract: Expert Tattooing: The Development of a Profession in Canada, 1891-1986 examines professional tattooing in Canada from the late nineteenth century to the mid 1980s, a period that saw the practice’s emergence, expansion, and mainstreaming in the country. Using several cities and regions as case studies and employing a breadth of sources including archival material, oral histories, print media, and visual culture, I explore how tattooists navigated their profession’s complex occupational terrain. Tattooing—as a form of work, cultural practice, and social sphere—was much more pervasive and normalized than is often presumed. I provide a counterpoint to such misconceptions, which have marginalized those involved with tattooing, their contributions to the cities they lived and worked in, and the array of visual culture produced in the process. Using Ottawa as a loose geographic frame, I begin by developing my theoretical and methodological approach and examine the concept of “professional” as it relates to tattooing. I then assess how authorities across Canada used legal, moral, and health concerns to control tattooing while considering how tattooers worked within and against regulation. Next, I investigate tattooing in Toronto and beyond through the relationship between tattooists and print media, which I position as a medium that captured and distributed the profession’s oral discourse. The following case study examines tattooing in Vancouver and Victoria by analyzing the circulation of people, images, and knowledge, in, out, and around the two coastal cities. I then consider the relationship between tattooers and other cultural producers in Halifax by studying the visual culture produced as a result of their interaction. In my final substantive chapter, I interrogate connections between tattooing in Toronto and Japan through the work of fine artist Aba Bayefsky. Lastly, my epilogue considers the implications of this research through a tattoo artist named Nels Johnson who worked in Thunder Bay, Ontario. I argue that professional tattooing existed on a continuum of expertise, occupying the interstices between cultural production and work, on which practitioners developed methods to present themselves and their work as a legitimate, professional occupation.

abstract: PhD


title: Partial Molecular and Biochemical Characterization of a Sandhoff Mouse Model

contributor:
Walia, Jagdeep
Neuroscience Studies

subject:
RT-PCR
Mass Spectrometry
Gene Expression
Metabolomic Profiling
Sandhoff Disease
Animal Model

abstract: Sandhoff Disease (SD) is a rare genetic disorder which results in progressive neurodegeneration. SD is caused by a build-up of GM2 Gangliosides, a lipid which is stored in the lysosome of neurons. It can occur in infantile, juvenile and adult forms; in the severe, infantile form, death occurs by the age of 4. It is well understood that this lipid build-up is the result of a mutation of the HEXB gene, which results in a deficiency of the ‘beta-hexosaminidase A’ enzyme for which it codes; however, a better understanding of the pathology is needed. The objective of this study was, therefore, to better characterize SD to improve our understanding of the disease. This study took two approaches; the first approach was to monitor gene expression changes of six genes previously identified as showing increased expression the brains of 4 week old SD mice. Three of these genes were related to inflammation: Ccl3, Lyz, and Wfdc17; whilst three genes were related to myelination: Ugt8a, Fa2h, and Mog. They were assessed at 3 time points: 5 weeks, 10 weeks, and 16 weeks. Secondly, this study profiled metabolite changes in the serum and urine of SD mice, at the same time points, through the use of mass spectrometry. Gene expression analysis showed that there is an inflammatory response occurring from 5 weeks in SD mice that continues to increase over the course of the disease. Demyelination was also shown to occur, varying with disease progression. Metabolomic analysis showed a decrease in two metabolites of glycerophospholipids and acylcarnitines suggesting that the breakdown and synthesis is interrupted downstream of the GM2 Ganglioside storage. Lastly, consistent with other findings, we have shown amino acids (particularly alanine) to be elevated, which is a likely consequence of increased demand for energy following the interruption of lipid breakdown and reduced food intake. Whilst this study did not identify any candidate biomarkers for SD, it has contributed towards the understanding of the pathology behind the disease. Future studies will be needed to further characterize SD in mouse models and in humans.

abstract: M.Sc.


title: Advanced Devolatilisation model for Lagrangian particles in OpenFOAM

contributor:
Matovic, Darko
Mechanical and Materials Engineering

subject: CFD

subject: coal

subject: dual competing devolatilisation rate model

subject: lagrangian particle

abstract: To study the devolatilisation process associated with coal combustion, computational fluid dynamics (CFD) is a very useful tool. The aim of this thesis is to accurately model coal devolatilisation at high temperatures associated with cement kilns to facilitate the further study of coal combustion within a cement kiln, to increase combustion efficiency thereby decreasing the environmental impact associated with cement production. The devolatilisation process can be modeled using two main types of models: the global and the structural model. Global models use parameters found by a simple kinetic analysis whereas the structural models require thorough analysis of the coal particles chemical structure. Due to it's simplicity and ability to model all types of coal without relying on in-depth analytical methods and parameter predictions for unknown coal types, the global model of the 'dual-competing rate' type was used. This model was implemented and optimized in the open-source CFD software OpenFOAM to allow increased accuracy when examining high temperature, high heating rate, and/or multi-peak rate volatile release coal devolatilisation. It has proven to be effective in high temperature and heating rate scenarios (such as those found in a cement kiln) and when modelling multi-peak rate volatile releases. Additionally, the particle specific heat (cp) model used within the original OpenFOAM code was modified as it does not allow for particle phase or specie mass fraction modifications without altering the particle cp value. Due to the high working temperatures, the Kirov cp model is used. The implementation of both models have shown an increase in high temperature devolatilisation dynamics and heating rate accuracy in addition to an increase in modelling multi-peak rate volatile release accuracy by a factor of 5 when compared to the single kinetic rate model.

abstract: M.A.Sc.