title: Effect of Starting Microstructure and CGL Compatible Thermal Processing Cycle on the Mechanical Properties of a Medium Mn Third Generation Advanced High Strength Steel

contributor:
McDermid, Joseph
Materials Science and Engineering

subject:
Medium Mn TRIP Steel
3G-AHSS
Retained Austenite
Mechanical Properties
Overaging Temperature Holding Time
CGL Compatible Thermal Processing Cycle

abstract: Medium Mn TRIP steels are amongst the most widely researched third generation advanced high strength steels (3G-AHSSs) as they are ideal candidates for automotive light-weighting applications owing to their superior strength and ductility balance. However, the thermal processing cycles of these steels need to be compatible with the industrial continuous galvanizing line (CGL) in order to successfully employ them in the automotive manufacturing industry. The main objective of the present research was to develop a CGL compatible thermal processing cycle for a prototype medium Mn steel that would produce significant volume fractions of chemically stable retained austenite and exhibit mechanical properties consistent with established 3G-AHSS targets. In that regard, the effects of intercritical annealing (IA) time and temperature and starting microstructure were determined in the first part of this research. The as-received tempered martensite (S-TM) and heat treated martensite (S-M) were the two different starting microstructures studied in this research. In this case, the overaging temperature (OT) treatment (460°C for 20s) was kept constant. It was found that high volume fractions (≥ 0.30) of retained austenite were achieved for S-M samples intercritically annealed at 675°C for shorter times (i.e. 60 to 120s) compared to S-TM samples. TEM analysis of the S-M samples showed that most of the retained austenite was present in a film type morphology, which is known to be more stable chemically and mechanically compared to the block type morphology. The tensile test results showed that although both the S-TM and S-M samples exhibited a high strength/ductility balance, the S-M samples, particularly the S-M 675°C + 120s samples, showed more potential in terms of CGL compatibility and achieving 3G-AHSS target mechanical properties. The effect of OT holding time was determined in the second part of this research. In that regard, the OT holding time was varied form 20s to 120s for selected S-TM and S-M samples. The S-TM 710°C samples with increased OT holding times (60s and 120s) had a significant increase in retained austenite volume fraction compared to the baseline 20s OT samples. However, the retained austenite volume fractions did not change for S-M samples regardless of OT holding time. It was also found that the mechanical properties of the annealed S-TM and S-M steels depended on the OT holding time. For the S-TM samples with > 120s IA holding times, longer OT holding times (60s and 120s) produced chemically unstable retained austenite which transformed rapidly at low strain resulting in low UTS × TE products. However, although longer OT holding times significantly increased the yield strength of the annealed S-M samples, the UTS × TE product decreased significantly owing to decreased retained austenite stability. Finally, based on the results of this research, it was concluded that the prototype medium Mn TRIP steel can achieve 3G-AHSS target mechanical properties using CGL-compatible thermal processing cycles. Moreover, depending on successful reactive wetting, it may be possible to perform both thermal processing and galvanizing of this steel in the industrial CGL.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Cultural Political Economy of Financial Literacy in Turkey

contributor:
McBride, Stephen
Political Science

subject:
financial literacy
turkey
cultural political economy
international political economy

abstract: Financial literacy is commonly defined as the knowledge, skills, and ability to navigate the increasingly complex financial markets, and is considered to empower consumers to make responsible financial decisions. Financial literacy is increasingly promoted as a crucial life skill in the aftermath of global financial crisis by numerous global initiatives and became part and parcel of national strategies of financial inclusion. By utilizing theoretical insights from Michel Foucault’s late work on governmentality, this dissertation analyzes financial literacy education initiatives in Turkey with ethnographic research. Cultural political economy perspective articulated in this dissertation underlines the importance of theorizing the financialized capital accumulation dynamics together with the reshaping of culture and the constitution of financialized subjectivities. It is argued that financial literacy is a “technique of the self” seeking to govern the everyday conduct of subjects in line with the long-term interests of financial capital. Financial literacy curricula provide not only the basic knowledge of finance but also instruct subjects ways to conduct oneself on financial planning, budgeting, debt management, creditworthiness, saving and investment. Financial literacy agenda deepens neo-liberal governmentality with the promotion of entrepreneurial subjectivity and responsibilization of individuals for social risks such as unemployment, economic downturn, and pensions. By problematizing the constitution of financially literate subjectivity and providing an everyday and cultural perspective on financialization, this dissertation contributes to the discipline of International Political Economy.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)


title: HEALTH SERVICE UTILIZATION OF LATE PRETERM INFANTS

contributor:
McDonald, Sarah
Health Research Methodology

subject:
neonatology
preterm infants
late preterm infants
health service utilization
admissions
emergency department visits
healthcare cost
cost analysis
cohort study
systematic review
meta-analysis

abstract:
Preterm birth (< 37 weeks gestation) is a major health burden for affected children. Although the risk of health problems increases as the gestational age decreases, research in the last decades has revealed that even late preterm infants born at 34-36 weeks gestational age have higher mortality and morbidity than term infants. Because late preterm infants constitute three fourths of preterm infants, they are important from both public health and health policy perspectives. This doctoral thesis sought to answer important knowledge gaps in health service utilization of late preterm infants via three studies.
	Study A, a systematic review and meta-analysis comparing health service utilizations of late preterm infants with those of term infants, found that late preterm infants had increased hospitalization compared with term infants that persisted from the neonatal period through adolescence. Study B is a cohort study evaluating the re-admissions and emergency department visits by late preterm and term singletons and twins for the first 5 years after birth. Study B demonstrated that late preterm infants had higher re-admission rates than term infants although differences in twins were less pronounced than in singletons. Study C is a population-based cohort study with cost analyses assessing the health care costs and resource utilization related to three different discharge timings of late preterm and term singletons: early (< 48 hours), late (48-71 hours), and very-late (72-95 hours) discharge after birth. Study C found that early discharge was not associated with the reduction of health care cost in late preterm infants, and instead was associated with an increase in the cost in term infants over the first year after birth. These findings are useful for parents, care providers, health policy makers, and guideline developers to provide optimal care for late preterm infants.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Studies of Alignment of Copper Phthalocyanine Compounds on Au(111) and Sidewall Functionalization of Single-Walled Carbon Nanotubes with Scanning Tunneling Microscopy

contributor:
Kruse, Peter
Chemistry

subject: alignment of copper phthalocyanine, compounds, sidewall functionalization, carbon nanotubes, scanning tunneling microscopy, molecular electronics

abstract:
 This thesis consists of two projects: alignment of copper phthalocyanine compounds on Au(111) and sidewall functionalization of single-walled carbon nanotubes on graphite. Both of these projects are performed with scanning tunneling microscopy (STM), which is used to study the structure of modified surfaces that are of interest in molecular electronics.

 In the first project, copper phthalocyanine compounds are made into a thin film with different methods, such as solution deposition, self-assembly and Langmuir-Blodgett film deposition. Those films are important materials in photoelectric devices such as organic light emitting diodes (OLED's). Molecules in these films are aligned on the solid surface with face-on orientation or edge-on orientation. However, the films of molecules with face-on orientation are preferentially used in LED's. In this project, we focus on finding a method to force molecules with face-on orientation in the film. The structure of copper octakisalkylthiophthalocyanine films on Au(111) was investigated with STM under ambient conditions. Columns of molecules are commonly observed due to the π-π interaction between molecules. The presence and length of alkyl chains in the molecules affects the alignment of molecules on the gold surface. The weak interaction between molecules and substrate caused the structure to be easily modified by an STM tip.

 In addition, chemical sidewall functionalization of SWCNTs was also explored with STM under ambient conditions. It was found that the spatial distribution of functional groups on nanotube sidewall is not random. Understanding the rules behind the distribution of functional groups will allow scientists to better control carbon nanotube functionalization and improve the properties of nanotubes. High resolution STM images provide direct evidence of the distribution and the effects of functional groups on nanotubes. Possible mechanisms are proposed to elucidate the process of
SWCNT functionalization by free radicals and via the Bingel reaction.

abstract: Thesis

abstract: Master of Science (MSc)


title: Synthesis and Thermal Response of Poly(N-Isopropylacrylamide) Prepare By Atom Transfer Radical Polymerization

contributor:
Stöver, Harald D. H.
Chemistry

subject: synthesis, thermal response, atom transfer, radical polymerization, PNIPAM, narrow-disperse, phase transition

abstract:
 Poly(N-isopropylacrylamide) (PNIPAM) has attracted much attention as a thermo-responsive polymer. However, the molecular weight (MW) dependence of its phase transition temperature is still controversial. This situation is largely due to the difficulty in synthesizing narrow-disperse PNIPAM. We have addressed the challenge and developed an atom transfer radical polymerization (ATRP) method to prepare narrow-disperse PNIPAM with moderate to high conversions, using branched alcohols as solvents. Aqueous solutions of these narrow-disperse PNIPAMs showed a dramatic decrease of the phase transition temperature with increasing molecular weight, as measured by turbidimetry and differential scanning calorimetry. Four other series of narrow-disperse PNIPAM with well-controlled molecular weights and with end groups of varying hydrophobicity were also synthesized by ATRP using the corresponding initiators, which enabled us to resolve the MW and end group effects. All the four series of samples showed an inverse molecular weight (MW) dependence of their phase transition temperature. The magnitude of the MW dependence decreased when using more hydrophobic end groups. The end groups were observed to have effects on the cloud point temperature, on the shape of the cloud point curves, and on the enthalpy of the phase
transition.

abstract: Thesis

abstract: Master of Science (MSc)


title: Generation and Time Resolved Spectroscopic Studies of Methylphenylgermylene and its Dimer in Solution

contributor:
Leigh, William J.
Chemistry

subject: generation, time resolved, spectroscopic studies, methylphenylgermylene, dimer, solution, laser flash photolysis, reagents

abstract:
 Under 248 nm laser flash photolysis, the photodecomposition of 1,3,4-trimethyl-1-phenyl-1-germacyclopent-3-ene (28) in dry, deoxygenated hexane solution at 23 °C leads to the prompt formation of two transient species: phenylmethylgermylene (29) and its Ge=Ge doubly bonded dimer, 1,2-dimethyl-1 ,2-diphenyldigemene (30). The formation of 29 proceeds in high chemical yield as shown by the results of steady state trapping experiments with methanol and isoprene. The transient assigned to 29 exhibits λmax = 490 nm and decays with second-order kinetics (τ ~ 2 μs). The second transient, which is formed from the
latter, is assigned to digermene 30 and exhibits λmax = 420 nm and a lifetime, τ ~ 8 μs.
The assignments are based on comparisons to the spectra of other simple germylenes, such as dimethyl-, diphenyl and dimesitylgermylene as well as on the pattern of reactivity with trapping reagents in solution at room temperature.

 Reactions studied include N-H, O-H and Sn-H insertion reactions, the [1+2] addition to isoprene and t-butylacetylene, and halogen atom abstraction from carbon tetrachloride.

 Absolute rate constants for quenching of 29 with the above mentioned scavengers were obtained by direct measurement of the germylene decay kinetics, over the concentration range where the formation of the digermene was more than 70% quenched. This ensures that the decay of 29 was dominated by the reaction with the trapping reagent.

 Absolute rate constants for reaction of the same reagents with 30 have also been determined for most of the scavengers studied. However, the digermene was found to be considerably less reactive than phenylmethylgermylene in all cases.

 The trends in spectroscopic properties and reactivity of simple germylenes in solution are discussed.

abstract: Thesis

abstract: Master of Science (MSc)


title: On transverse stability of periodic waves in the Kadomtsev-Petviashvili equation

contributor:
Pelinovsky, Dmitry
Mathematics and Statistics

subject:
Mathematics
Applied Mathematics

abstract: This thesis is devoted to the proof of linear stability of the one-dimensional periodic waves in the Kadomtsev-Petviashvili (KP-II) equation with respect to two-dimensional bounded perturbations. The method of the proof is based on the construction of a self-adjoint operator K such that the operators JL and JK commute, expresses a symplectic structure for the KP-II equation and L is a self-adjoint Hessian operator of the energy function at the periodic wave. In the situation when K is strictly positive except for a  nite-dimensional kernel included in the kernel of L, the operator JL has no unstable eigenvalues and the associated time evolution is globally bounded.

abstract: Thesis

abstract: Master of Science (MSc)


title: Enhanced Binding and Conformational Selectivity in Affinity Capillary Electrophoresis Using a Water-Soluble Resorcin[4]Arene as Intrinsic Buffer and Electrokinetic Host

contributor:
Britz-McKibbin, Philip
Chemistry

subject: enhanced binding, conformational selectivity, affinity capillary electrophoresis, water-soluble, resorcin[4]arene, intrinsic buffer, electrokinetic host

abstract:
 Affinity capillary electrophoresis (ACE) is a versatile technique for assessing non-covalent
molecular interactions in free solution provided that there are significant changes in apparent analyte mobility as a result of specific complexation. The thermodynamics of receptor binding are vital for controlling the selectivity in molecular recognition, which are dependent on the electrolyte composition of solution. In addition, the conformational properties of the complex (e.g., size, shape) can also contribute a secondary influence on receptor selectivity that has been relatively unexplored in ACE to date. In this study, dynamic 1:1 host-guest inclusion complexation involving a anionic resorcin[4]arene with a group of neutral corticosteroids was examined by ACE, where the macrocycle serves as both an intrinsic buffer and electrokinetic host. The tetraethylsulphonate derivative of 2-methylresorcin[4]arene (TESMR) was first
synthesized via an acid-catalyzed condensation reaction, which was then fully
characterized in terms of its weak acidity (pKa), mobility, UV spectral and buffer capacity properties. TESMR solutions were demonstrated to have stable intrinsic buffer and ion transport properties at pH 7.5 even at low ionic strength. It was determined that over a 200 % enhancement in the apparent binding constant (KB) was realized by ACE when using TESMR as an intrinsic buffer at pH 7.5 relative to an extrinsic sodium phosphate buffer system, which was also confirmed by 1H-NMR. The coupling of thermodynamic (KB) and electrokinetic (μep, AC) factors associated with complex formation in buffered aqueous solutions that minimize the effects of extrinsic electrolytes serves to enhance enthalpy-driven molecular recognition processes by ACE.

abstract: Thesis

abstract: Master of Science (MSc)


title: Design and Control of Human-Friendly Robots

contributor:
Bone, Gary M.
Mechanical Engineering

subject: design, control, human friendly, robots, manipulator impact, foam, virtual force field, collision-free paths

abstract:
In this thesis, solutions to two of the problems encountered in the design and control of human-friendly robots are investigated. The first problem is severe human injuries can occur when an accidental human-manipulator impact happens. A theoretical and experimental study on using foam coverings to reduce the severity of a human-manipulator impact and enhance human safety is presented. An improved human-manipulator impact model that incorporates the manipulator dynamics, foam covering dynamics and the coupling between the human head and torso is introduced. A method for approximating the configuration-dependent dynamics of robotics manipulators with the dynamics of a single DOF manipulator is proposed. With this model, the design parameters that significantly influence the human head acceleration are investigated. A model-based foam covering design procedure to properly select parameters of foam coverings in accordance with safety criteria and the foam thickness constraint is then proposed. The impact model and the foam covering design procedure are validated experimentally with two manipulators. The maximum error between the predicted and experimental head acceleration was less than 9%. The maximum error between the
predicted and experimental foam compressed depth was less than 12%. The second problem is mobile robot navigation in the presence of humans and other motion-unpredictable obstacles. A novel navigation algorithm, based on the virtual force field (VFF) method, is proposed as a solution. It features improved functions for the repulsive and detour virtual forces, and a new stabilizing virtual force. Methods to calculate sizes of the active and critical regions for different obstacles are developed. Stability of the new VFF is proven using a novel piecewise Lyapunov function and Lyapunov's second method. Based on simulations for different obstacle configurations, the new VFF-based algorithm successfully produces collision-free paths while five well known navigation algorithms incurred collisions in one of the configurations. With the new VFF-based navigation algorithm, simulations and experiments are successfully performed with a holonomic robot and a nonholonomic robot for several configurations, including multiple moving obstacles.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Regulation and function of the Lhx gene, lin-11, in Caenorhabditis elegans nervous system development

contributor:
Gupta, Bhagwati
Biology

subject:
Lhx
lin-11
LIM-Hox
C. elegans
Neuron
Intron evolution

abstract:
Lhx genes are a sub-family of Hox genes that play important roles in animal development.
In Caenorhabditis elegans there are seven Lhx genes, including the founding
family member lin-11. The lin-11 gene is necessary for the specification of neuronal
and reproductive tissues. My thesis work has involved understanding the mechanism of
lin-11 regulation and its function in these tissues. To this end, I addressed two distinct
but complementary questions, one of which focused on how transcriptional regulation of
lin-11 occurs and the second on the role of LIN-11 protein domains/regions.
My work on the transcriptional regulation has uncovered important roles of two of the
largest lin-11 introns, intron 3 and intron 7. These introns promote lin-11 expression
in non-overlapping sets of amphid neurons. Based on gene expression patterns and
behavioural assays, intron 3 is capable of restoring lin-11 function in lin-11(n389 ) null
mutant allele. Comparison of intron 3-driven reporter expression in the neuronal cell
types between C. elegans and C. briggsae has revealed cis and trans evolutionary changes
in lin-11 regulation between the two species. Functional dissection of the introns in C.
elegans has led to the identification of three distinct non-overlapping enhancers, each
specific for a single amphid neuron, i.e., RIC, AIZ, and AVG. I have also identified
four transcription factors, SKN-1, CEH-6, CRH-1, and CES-1, that act through these
enhancers to regulate neuronal expression of lin-11.
Furthermore, I have characterized the function of the LIM domains and a proline-rich
(PRR) C-terminus region of LIN-11 in the specification of neuronal and reproductive
tissues. My work shows that while the LIM domains are required for LIN-11 function
in these tissues, the PRR region is dispensable. I have also examined the functional
conservation of lin-11 domains using two other Lhx genes, Drosophila melanogaster
(dLim1) and Mus musculus (Lhx1 ), and found that both of these genes were able to
rescue lin-11 defects. Together, my work has significantly advanced our understanding
of transcriptional regulation of lin-11, the importance of LIM domains in tissue formation,
and functional conservation of Lhx genes across phyla.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: A New Feature Coding Scheme for Video-Content Matching Tasks

contributor:
Chen, Jun
Electrical and Computer Engineering

subject: Video Matching, Descriptor coding, Transform coding, Feature location coding, Variable size histogram location coding

abstract: This thesis present a new feature coding scheme for video-content matching tasks. The purpose of this feature coding scheme is to compress features under a strict bitrate budget. Features contain two parts of information: the descriptors and the feature locations. We propose a variable level scalar quantizer for descriptors and a variable block size location coding scheme for feature locations. For descriptor coding, the SIFT descriptors are transformed using Karhunen-Loéve Transform (KLT). This K-L transformation matrix is trained using the descriptors extracted from the 25K-MIRFLICKR image dataset. The quantization of descriptors is applied after descriptor transformation. Our proposed descriptor quantizer allocates different bitrates to the elements in the transformed descriptor according to the sequence order. We establish the correlation between the descriptor quantizer distortion and the video matching performance, given a strict bitrate budget. Our feature location coding scheme is built upon the location histogram coding method. Instead of using uniform block size, we use different sizes of blocks to quantize different areas of a video frame. We have achieved nearly 50% reduction in the bitrate allocated for location information compared to the bitrate allocated by the coding schemes that use uniform block size. With this location coding scheme, we achieve almost the same video matching performance as that of the uniform block size coding. By combining the descriptor and location coding schemes, experimental results have shown that the overall feature coding scheme achieves excellent video matching performance.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Investigation of KcsA Activation Using Ion Channel Recording Techniques

contributor:
Yang, Daniel S.C.
Biochemistry and Biomedical Sciences

subject: investigation, KcsA activation, ion channel, recording techniques, selective flow

abstract: Potassium channels allow selective flow of K+ ions across impermeable membranes. They switch between closed and open states in response to stimulus. The closed state of KcsA, a potassium channel from the bacteria streptomyces lividans, has been crystallized and studied. However, attempts to obtain a structural description of gating transition of the channel have been hampered because the open state is transiently occupied. In this study, we investigated changes in gating functions of KcsA caused by variations in environmental parameters such as pH, voltage and also mutation in KcsA using planar bilayer and patch clamp channel recording techniques to improve our understanding on the functional aspect of gate activation of KcsA.

abstract: Thesis

abstract: Master of Science (MSc)


title: MEASUREMENT OF QUALITY OF LIFE OF PATIENTS WITH TYPE 2 DIABETES IN CHINA

contributor:
Xie, Feng
Health Research Methodology

abstract:
Background: As one of the major global chronic diseases, diabetes mellitus (DM) places substantial humanistic and economic burdens on patients and their families, healthcare systems and society. Type 2 DM (T2DM) accounts for about 90% of cases of diabetes, and it causes heavier impairment on patients’ quality of life (QoL) compared to type 1 DM. China has the world's largest type 2 diabetic patient (T2DP)population. However, little is known about the determinants of long-term QoL of Chinese T2DP. The Chinese Diabetes Quality-of-life (DQOL) measure is one of the most commonly used diabetes-specific QoL measures in Chinese clinical research. Patients have identified the long length of the DQOL a challenge for its implementation. In addition, since it is not a preference-based measure, the Chinese DQOL measured QoL data also cannot be employed in cost-utility analysis, which can achieve a broader economical comparison of interventions across different disease areas in the medical decision-making process. Therefore, this thesis aimed to 1) identify both statistically significant and clinically relevant determinants of long-term QoL of Chinese T2DPs, 2) develop a short version for the Chinese DQOL, and 3) map the Chinese DQOL onto the generic preference-based QoL instrument, EuroOoL5 dimensions 3-level (EQ-5D-3L).
Methods: Data from a longitudinal observational study which recruited clinically diagnosed T2DPs (n=2,886) from community health centers in five Chinese cities was used. The Chinese DQOL and EQ-5D-3L were administered, and demographics, diabetes-related, and other health-related information was collected at baseline and at the end of 12 months. We used anchor-based approach to estimate the minimally important difference (MID) of the Chinese EQ-5D-3L for T2DP. The MID was used to identify the clinically relevant change in QoL over a one-year period for this patient population. Then logistic and ordered logistic regression models were fitted to identify statistically significant factors that explain these clinically relevant changes. Both the classical test theory and item response theory, each combined with exploratory factor analysis, were applied to reduce the number of items of the Chinese DQOL. Using the same data set, we also estimated the mapping algorithm between the Chinese DQOL (and its short version) and the Chinese EQ-5D-3L index by exploring different estimators and model specifications.
Results and conclusions: This thesis estimated the MID of the EQ-5D-3L index was 0.0262 for Chinese T2DP and found that age, gender, education, income, exercise, and glycosylated hemoglobin level were the statistically significant and clinically relevant factors predicting a change in QoL for ChineseT2DP over a one year period. We provided a 24-item short version for the 46-item Chinese DQOL to reduce the patients’ burden in future clinical research. Mapping algorithms using age, gender, and domain scores were also established to map the original Chinese DQOL and the short version onto the EQ-5D-3L index.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Macrophage SR-BI and Atherosclerosis

contributor:
Trigatti, Bernardo L.
Biochemistry and Biomedical Sciences

subject: macrophage, atherosclerosis, Scavenger Receptor, integral membrane protein, tissue

abstract:
 The Scavenger Receptor, Class B, Type I (SR-BI) is an integral membrane protein whose expression in the liver is critical to reverse cholesterol transport by mediating the selective uptake of HDL-derived cholesterol. SR-BI is expressed in a variety of tissues including bone marrow derived macrophages and foam cells in atherosclerotic lesions. We have explored the effect of eliminating SR-BI in leukocytes on advanced stages of atherosclerotic plaque development in apoE KO mice. We observed statistically significant cardiomegaly as a result of the elimination of SR-BI in bone marrow derived cells compared to controls (P=0.02). We report that the elimination of SR-BI in bone marrow derived cells in apoE KO mice induced to undergo atherosclerosis by feeding a high fat diet for four weeks leads to no significant difference in cross-sectional atherosclerotic plaque area at the aortic root (4.9±0.9x10^4 μm^2 when SR-BI-/- apoE-/- --> apoE-/- [n=9] and 5.5±0.9x10^4 μm^2 when SR-BI +/+ apoE-/- --> apoE -/- [n=12], P=0.68) or plaque volume through the aortic sinus (1.8±0.3x 10^7 μm^3 when SR-BI-/- apoE-/- --> apoE-/- [n=9] and 1.9±0.3x10^7 μm^3 when SR-BI +/+ apoE-/- --> apoE -/- [n=12], P=0.69). We demonstrate that macrophage SR-BI protein expression can be decreased by cholesterol associated with lipoproteins. Furthermore, we report that in Raw 264.7 macrophage-like cells the expression of SR-BI can also decrease in response to glucosamine treatment. The expression of SR-BI is decreased significantly in cells
overexpressing SR-BI (1d1A[mSR-BI] cells [P=0.003]) due to treatment with glucosamine with increased protein mobility. We support this finding by demonstrating that this difference may be the result of altered glycosylation.

abstract: Thesis

abstract: Master of Science (MSc)


title: Tracking Pedestrians with Known/Unknown Interactions and Influences

contributor:
Kirubarajan, Thia
Electrical and Computer Engineering

subject:
pedestrian tracking
multiple model social forces filter
social force Kalman filter
parameter estimation with tracking
dependent motion tracking
social force PhD filter

abstract:
This thesis addresses the problem of tracking multiple ground targets whose motion is dependent on one another. Multiple approaches which integrate the social force based motion model into different filtering algorithms are proposed. The social force concept has previously been used to model pedestrian motion where the interactions among pedestrians are described using social forces.

First, the social force based motion model integrated into the Probability Hypothesis Density (PHD) framework is proposed. Two different implementations, namely, the Sequential Monte Carlo (SMC) technique and the Gaussian Mixture (GM) technique, are derived to implement the proposed Social Force PHD (SF-PHD) filter in ground target tracking scenarios. Next, a social-force-based motion model integrated into the stacked Kalman filter (stacked SF-KF) is developed and its multiple model (stacked IMM-SF-KF) variant is derived. Then, the assumption used in the proposed algorithms, that the actual values of the social force parameters are known, is not valid at all times and the assumption is relaxed. Hence, simultaneous parameter estimation techniques for the social force parameters during the tracking are proposed. Three approaches based on the state augmentation method, the Expectation
Maximization (EM) method and the maximum likelihood method are derived. The maximum likelihood method can be implemented offline or online, depending on the requirement. The traditional Posterior Cramer Rao Lower Bound (PCRLB), which is the inverse
of the Fisher information matrix, gives a bound on the optimal achievable accuracy of the estimated state of a target with independent motion. Subsequently, a modified performance measure based on the PCRLB for targets whose motion is dependent
on each other is derived to validate the performance of the proposed algorithms. Finally, the PCRLB that accounts for unknown interactions is derived to validate the proposed simultaneous parameter estimation techniques. Simulated and real data are
used to show the performance of the proposed algorithms and simultaneous parameter estimation techniques compared to the algorithms in the literature.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract:
This thesis addresses the problem of tracking multiple ground targets whose motion is dependent on one another. In target tracking literature, it is commonly assumed that a target’s motion follows a nearly constant velocity, constant turn or a constant acceleration model independent of the motion of other targets. But the actual behavior of a ground target may be more intricate than that and it is often affected by the motion of other targets, obstacles in the surrounding and its intended destination. Hence, a more sophisticated motion modeling technique, which integrates the various factors that affect the motion of ground targets, is needed. In this thesis, multiple approaches which integrate the social force based motion model into different filtering algorithms are proposed. The social force concept has previously been used to model pedestrian motion where the interactions among pedestrians are described using social forces.

First, the social force based motion model integrated into the Probability Hypothesis Density (PHD) framework is proposed. Two different implementations, namely, the Sequential Monte Carlo (SMC) technique and the Gaussian Mixture (GM) technique, are derived to implement the proposed Social Force PHD (SF-PHD) filter in ground target tracking scenarios. Next, a social-force-based motion model integrated into the stacked Kalman filter (stacked SF-KF) is developed and its multiple model (stacked IMM-SF-KF) variant is derived. Then, the assumption used in the proposed algorithms, that the actual values of the social force parameters are known, is not valid at all times and the assumption is relaxed. Hence, simultaneous parameter estimation techniques for the social force parameters during the tracking are proposed. Three approaches based on the state augmentation method, the Expectation
Maximization (EM) method and the maximum likelihood method are derived. The maximum likelihood method can be implemented offline or online, depending on the requirement. The traditional Posterior Cramer Rao Lower Bound (PCRLB), which is the inverse of the Fisher information matrix, gives a bound on the optimal achievable accuracy of the estimated state of a target with independent motion. Subsequently, a modified performance measure based on the PCRLB for targets whose motion is dependent
on each other is derived to validate the performance of the proposed algorithms. Finally, the PCRLB that accounts for unknown interactions is derived to validate the proposed simultaneous parameter estimation techniques. Simulated and real data are
used to show the performance of the proposed algorithms and simultaneous parameter estimation techniques compared to the algorithms in the literature.


title: The Role of AP-2⍺ and AP-2β in Amacrine Cell Development and Patterning

title: The Role of AP-2⍺ and AP-2β in Retinal Development

contributor:
West-Mays, Judith
Biomedical Engineering

subject:
retina
development
amacrine cell
mosaic patterning

abstract: Previous studies from our lab have shown that Activating protein-2 (AP-2) transcription factors, AP-2α and AP-2β are important in retinal development, specifically in the developing horizontal and post-mitotic amacrine cells. Conditional deletion of AP-2α and AP-2β from the retina of mice resulted in a variety of abnormalities including loss of horizontal cells, defects in the photoreceptor ribbons in which synapses failed to form, along with evidence that amacrine cell mosaic patterning may be disrupted. The current thesis examined the neural retina of these AP-2α and AP-2β conditional mice in greater detail using immunofluorescence of histological sections and whole retinas, and electroretinograms to measure retinal function in post-natal adult mice. Examining regularity of the amacrine cell mosaics of these double mutants showed the loss of AP-2α and AP-2β led to significant irregularities in the mosaic patterning of these cells as determined by Voronoi domain areas (P<0.01) and nearest-neighbour distances (P<0.03). No significant changes in amacrine population numbers were observed. Observed cellular changes in the double conditional knock out mice were reflected as a change in the retinal response to light as recorded by electroretinograms. For example, the b-wave amplitude, representative of the interneuron signal processing, was significantly affected in those mice lacking AP-2⍺ and AP-2β (P<0.0001). Taken together, the work presented in this thesis implicates the requirement of AP-2⍺ and AP-2β for the correct amacrine mosaic patterning and for the proper functional light response in the retina.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Combining Capital and Operating Expenditure Costs in Vehicular Roadside Unit Placement

contributor:
Todd, Terence D.
Electrical and Computer Engineering

abstract:
Vehicular ad-hoc networks will be the next step towards intelligent transportation systems. Roadside infrastructure is a key component of these systems that will eventually support various applications such as road safety, transportation services, infotainment, and in-vehicle Internet access.

This thesis considers the problem of roadside unit (RSU) placement and configuration in vehicular networks. The goal is to select the RSU locations and configurations such that the sum of capital and operational expenditure costs is minimized. Historical vehicular traffic traces and a set of RSU candidate locations are used as inputs. First, the problem is formulated as an integer linear program (ILP), which provides a lower bound on the total cost, and can be found for moderate size problems. A practical algorithm called Minimum Cost Route Clustering (MCRC) is then introduced that solves a relaxed version of the ILP and uses a novel rounding procedure to obtain real RSU placements. The algorithm takes into account the energy costs incurred by transmitting vehicular requests when the latter are scheduled using a minimum energy online scheduler. Performance results are presented that show that the proposed algorithm performs well compared to the case where placements are done without considering both capital and operational expenditure costs.

The problem of capacity augmentation is then addressed, as a way of adjusting the initial RSU network design, and serves to counterbalance its failure to take causality into account. The objective is to find an RSU radio capacity assignment that minimizes the long-term operating expenditure costs subject to meeting packet deadline constraints, subject to a given packet loss rate target. A procedure, referred to as the Capacity Augmentation (CA) Algorithm, is proposed that iterates over the RSUs, selecting candidates for capacity augmentation based on their packet loss rate sensitivities. A variety of results is presented that characterize and compare the performance of the CA Algorithm using a greedy online packet scheduler. It is shown that the CA Algorithm is an efficient way to assign RSU radio capacity that achieves the desired performance objectives.

The thesis then considers the problem of RSU job scheduling when vehicle routes are unknown. The objective is to minimize the long-term RSU energy costs, subject to satisfying hard deadline constraints and a packet loss criterion. A scheduler referred to as the Route Coverage Expectation Scheduler (RCES) is proposed that uses the historical traffic traces of an urban road network to estimate vehicular motion and the energy costs needed for RSU-to-vehicle communications. The algorithm schedules job requests across multiple RSUs whenever possible, by assigning part of a request to the current RSU and by deferring the remainder to future RSUs. A variety of results is presented that show that the RCES Algorithm achieves a packet drop ratio similar to that achieved when routes are known, with only a modest increase in energy cost.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: On the Existence of Non-Zero Linear Continuous Functionals on Fréchet Spaces

contributor:
Husain, T.
Mathematics

subject: existence, non-zero, linear, continuous, functionals, Fréchet spaces, separation

abstract: This thesis is concerned with a necessary and sufficient condition for the existence of non-zero linear continuous functionals on Fréchet or more general topological vector spaces. The main idea is based on the famous Hahn-Banach theorem. Since the connection between Hahn-Banach theorem and separation theorems is well known, here we study some separation theorems as well.

abstract: Thesis

abstract: Master of Science (MSc)


title: Understanding the AroA Mechanism: Evidence for Enolpyruvyl Activation and Kinetic Isotope Effect Measurements

contributor:
Berti, Paul J.
Biochemistry and Biomedical Sciences

subject: AroA mechanism, evidence, Enolpyruvyl Activation, kinetic isotope effect, mesurements, transfer reaction, hydrolysis, protonation

abstract:
 AroA catalyzes a carboxyvinyl transfer reaction, forming enolpyruvyl shikimate 3-phosphate (EPSP) from shikimate 3-phosphate (S3P) and phosphoenolpyruvate (PEP). Upon extended incubation, it forms EPSP ketal by intramolecular nucleophilic attack of O4H on C2' of the enolpyruvyl group. EPSP ketal was previously proposed to form by non-enzymatic breakdown of the tetrahedral intermediate (THI) which had dissociated from AroA. In this study, EPSP ketal formed in the presence of excess AroA, which demonstrated that it was formed in the active site. This eliminated non-enzymatic THI breakdown as its source, and demonstrated that AroA forms either a discrete EPSP cationic intermediate, or cl transition state with high cationic character. The pH dependence of non-enzymatic EPSP hydrolysis was examined in order to understand the intrinsic reactivity of the enolpyruvyl group. Acid catalysis accelerated EPSP hydrolysis> 10^8-fold. These results provide evidence for
enolpyruvyl activation through protonation at C3', forming an unstable cationic intermediate, or a highly cation-like transition state. The incorporation of 2H into EPSP from solvent 2H20 during AreA-catalyzed hydrolysis was much slower than the hydrolysis rate, in the absence of inorganic phosphate in the reaction. This demonstrated that KIEs on AroA-catalyzed EPSP hydrolysis, when they are measured in the future, will reflect protonation of EPSP. A method was developed for KIE measurements on acid-catalyzed EPSP hydrolysis, which showed good reproducibility and no buffer dependence. Further experiments need to be completed on the acid-catalyzed KIEs and enzyme-catalyzed KIEs, followed by transition state analysis. This will precisely define the transition state structure of the enzyme-catalyzed EPSP hydrolysis reaction, and provide a good starting point for designing AroA inhibitors.

abstract: Thesis

abstract: Master of Science (MSc)


title: Semi-supervised Information Fusion for Clustering, Classification and Detection Applications

contributor:
Jeremic, Aleksandar
Electrical and Computer Engineering

subject: Information fusion, Semi-supervised learning, Detection, Clustering, New Cluster Detection

abstract:
Information fusion techniques have been widely applied in many applications including clustering, classification, detection and etc. The major objective is to improve the performance using information derived from multiple sources as compared to using information obtained from any of the sources individually. In our previous work, we demonstrated the performance improvement of Electroencephalography(EEG) based seizure detection using information fusion. In the detection problem, the optimal fusion rule is usually derived under the assumption that local decisions are conditionally independent given the hypotheses. However, due to the fact that local detectors observe the same phenomenon, it is highly possible that local decisions are correlated. To address the issue of correlation, we implement the fusion rule sub-optimally by first estimating the unknown parameters under one of the hypotheses and then using them as known parameters to estimate the rest of unknown parameters.

In the aforementioned scenario, the hypotheses are uniquely defined, i.e., all local detectors follow the same labeling convention. However, in certain applications, the regions of interest (decisions, hypotheses, clusters and etc.) are not unique, i.e., may vary locally (from sources to sources). In this case, information fusion becomes more complicated. Historically, this problem was first observed in classification and clustering. In classification applications, the category information is pre-defined and training data is required. Therefore, a classification problem can be viewed as a detection problem by considering the pre-defined classes as the hypotheses in detection. However, information fusion in clustering applications is more difficult due to the lack of prior information and the correspondence problem caused by symbolic cluster labels.

In the literature, information fusion in clustering problem is usually referred to as clustering ensemble problem. Most of the existing clustering ensemble methods are unsupervised. In this thesis, we proposed two semi-supervised clustering ensemble algorithms (SEA). Similar to existing ensemble methods, SEA consists of two major steps: the generation and fusion of base clusterings. Analogous to distributed detection, we propose a distributed clustering system which consists of a base clustering generator and a decision fusion center. The role of the base clustering generator is to generate multiple base clusterings for the given data set. The role of the decision fusion center is to combine all base clusterings into a single consensus clustering. Although training data is not required by conventional clustering algorithms (usually unsupervised), in many applications expert opinions are always available to label a small portion of data observations. These labels can be utilized as the guidance information in the fusion process. Therefore, we design two operational modes for the fusion center according to the absence or presence of the training data. In the unsupervised mode, any existing unsupervised clustering ensemble methods can be implemented as the fusion rule. In the semi-supervised mode, the proposed semi-supervised clustering ensemble methods can be implemented.
In addition, a parallel distributed clustering system is also proposed to reduce the computational times of clustering high-volume data sets. Moreover, we also propose a new cluster detection algorithm based on SEA. It is implemented in the system to provide feedback information. When data observations from a new class (other than existing training classes) are detected, signal is sent out to request new training data or switching from the semi-supervised mode to the unsupervised mode.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Low-Complexity Compression Techniques for High Frame Rate Video

contributor:
Chen, Jun
Wu, Xiaolin
Electrical and Computer Engineering

subject:
video compression
low-complexity
Slepian-Wolf coding
motion estimation and compensation

abstract: Recently, video has become one of the most important multimedia resources to be shared in our work and daily life. With the development of high frame rate video (HFV), the write speed from high speed camera array sensor to the massive data storage device has been regarded as the main constraints on HFV applications. In this thesis, some low-complexity compression techniques are proposed for HFV acquisition and transmission. The core technique of our developed codec is the application of Slepian-Wolf coding theorem in video compression. The light-duty encoder employs SW encoding, resulting in lower computational cost. The pixel values are transformed into bit sequences, and then we assemble the bits on same bit plane into 8 bit streams. For each bit plane, there is a statistical BSC being constructed to describe the dependency between the  source image and the SI image. Furthermore, an improved coding scheme is applied to exploit the spatial correlation between two consecutive bit planes, which is able to reduce the source coding rates. Different from the encoder, the collaborative heavy-duty decoder shoulders the burden of realizing high reconstruction fidelity. Motion estimation and motion compensation employ the block-matching algorithm to predict the SI image. And then the received syndrome sequence is able to be SW decoded with SI. To realize different compression goals, compression are separated to the original and the downsampled cases. With regard to the compression at the original resolution, it completes after SW decoding. While with respect to compression at reduced resolution, the SW decoded image is necessary to be upsampled by the state-of-the-art learning based SR technique:  A+ . Since there are some important image details lost after the resolution resizing,  ME and MC is applied to modify the upsampled image again, promoting the reconstruction PSNR. Experimental results show that the proposed low-complexity compression techniques are effective on improving reconstruction fidelity and compression ratio.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Investigating the Roles of a Putative Transmembrane Domain of Mammalian Diacylglycerol Kinase Epsilon

contributor:
Epand, Richard M.
Biochemistry and Biomedical Sciences

subject: putative, transmembrane, domain, mammalian, diacylglycerol, kinase epsilon, enzymes, plasma

abstract:
 An area of current research interest involves the diacylglycerol kinase (DGK) family. Diacylglycerol kinases (DGKs) are a group of enzymes that phosphorylate diacylglycerol (DAG), a second messenger involved in cell signaling. The product of this reaction, phosphatidic acid (PA), also has signaling roles. An interesting isoform is DGKε, that although it has no identifiable regulatory domains other than the C1 domains. In addition, the catalytic domain is homologous to that of other DGK isoforms; however, DGKε exhibits an unusual specificity toward acyl chains of DAG, selectively phosphorylating an arachidonoyl-DAG substituted at the sn-2 position. Recently, researchers have identified an N-terminal hydrophobic domain of about 19 amino-acids in human DGKε. The present study attempted to identify the function of the N-terminal putative transmembrane domain of human DGKε and its relationship to the activity and substrate specificity of this enzyme by designing a truncated form of DGKε lacking the putative transmembrane domain.

 We have shown that the putative transmembrane domain of DGKε is not required for enzyme activity or for substrate specificity. In a mixed micellar assay the enzyme-catalyzed reaction followed surface dilution kinetics with respect to diacylglycerol and followed Michaelis-Menten kinetics with respect to ATP. The results show that the truncated form of the enzyme maintains substrate specificity for lipids with an arachidonoyl moiety present at the sn-2 position. The truncation increased the catalytic rate constant for all three substrates used in this study.
It appears unlikely that the putative transmembrane domain, a segment unique to DGKε, has no functional role. It is possible that the hydrophobic segment may have a role in enzyme regulation by associating the enzyme in oligomers that are inactive in quiescent cells and get activated upon dissociation into monomers by increased levels of DAG in the membrane. We have shown that the presence of higher molecular species in the gel is not dependent on the presence or absence of the putative transmembrane domain. The only difference between the full-length and truncated enzyme is the monomer to dimer ratio. It appears likely that another segment of DGKε besides the putative transmembrane domain may be involved in oligomerization and that oligomerization is either transient or very weak. The absence of the hydrophobic domain of DGKε seems to cause no drastic changes either in the activity, the substrate specificity, or the state of oligomerization of the enzyme.

 Therefore, the next question is whether the hydrophobic domain of DGKε inserts itself in the membrane as a transmembrane helix or it only helps associate the enzyme to the surface of the membrane. We studied the topology of theN-terminal domain of DGKε in intact and permeabilized cells by indirect immunofluorescent microscopy. The results show that the N-terminal domain of the protein is present in the cytosol. The data supports a model in which the hydrophobic domain of DGKε forms a hydrophobic loop that attaches to the inner layer of the plasma membrane or that the hydrophobic domain attaches to the inner leaflet through its nonpolar surface of a horizontal helix. The first hypothesis is supported by the presence of a Pro residue in the middle of the hydrophobic domain. This Pro would introduce a kink in the helix creating a loop, but the absence of one or more glycine residues proximal to proline may hinder the formation of the loop. The second hypothesis is sustained by the presence of a polar surface
on one side of the helical wheel. This orientation indicates the presence of a slightly horizontal
helix attached to the surface of the inner layer of the plasma membrane.

 Regardless of the orientation of the helix, the weak association of the enzyme with the membrane is supported by previous data on the ease of extractability of the enzyme with high salts and on the Triton X-114 phase partitioning.

abstract: Thesis

abstract: Master of Science (MSc)


title: Silicone Surface Modification with Collagen and Its Biological Responses

contributor:
Brook, Michael A.
Chemistry

subject: silicone surface modification, collagen, biological responses, biocompactibility, covalent, proteins, tertiary structures

abstract:
 Collagen, due to its good biocompatibility and abundance in mammalian structures, has been widely applied in developing better biomaterials. There remains the need for yet more stable surfaces of biomaterials. One strategy to achieve this is improved binding to surfaces using covalent rather than physical linking. However, due to collagen's poor solubility in neutral or alkaline conditions, there are only a few papers describing covalently linked collagen so far, and they generally use acidic conditions to generate surfaces with only low collagen density. N-Hydroxysuccimide ester (NHS) chemistry has been widely used in covalently binding proteins, but the NHS activity and its preparation efficiency are plagued with undesired, premature hydrolysis. A two-step method was developed for making NHS functional surfaces with a non-fouling spacer, PEO. The process was more efficient and led to concentrated NHS surfaces. Collagen was successfully immobilized onto this NHS surface after optimizing the conditions for immobilization. The solubility problem was overcome by increasing the ionic strength of the solution. Abundant collagen molecules could then be immobilized on the silicone surface. ATR-FTIR was used as a diagnostic tool to prove the surface had been modified. The low water contact angle (40°) indicated the presence of collagen. XPS data showed a significant increase on the nitrogen content after tethering collagen molecules. Deep freezing ToF-SIMS displayed a decrease in the peak intensity for cationic fractions of collagen molecules when warming from -96 °C to room temperature, which suggested the surface rearrangement due to the hydrophilic character of collagen. Profilometer and tapping-mode AFM were used to investigate the surface morphology after modification. The latter showed a high density mesh work (immobilized collagen fibers) on the
collagen-modified surface. Collagen stain with Sirius Red F3B allowed us to look into the tertiary structures of covalently tethered collagen on the surface. However, it was found that only some of them were still in their native form. Interestingly, a subsequent epithelial cell culture assay showed that the cells grew very well on this collagen rich silicone surface. This suggested collagen's tertiary structure may not be necessary to support cell growth on the silicone surface covalently modified with collagen through the PEO spacer. However, further biochemical experiments are required to establish the underlying source of this observation.

abstract: Thesis

abstract: Master of Science (MSc)


title: Isolation of Flavonoids from Prunus Avium and Synthesis of Polyhydroxylated Pyrrolidines and Anilines as Potential Antibacterial Agents

contributor:
McNulty, James
Chemistry

subject: isolation of flavonoids, Prunus Avium, synthesis, polyhydroxylated pyrrolidine, anilines, antibacterial agents

abstract:
 This thesis describes the isolation and structural determination of flavonoids from the
heart wood of Prunus avium as well as synthesis of polyhydroxy pyrrolidine derivatives and aniline core structures as potential antibacterial agents. Nitrogen-synthons containing
saturated heterocyclic systems and aniline core structures are important synthons in
organic chemistry because of their presence in many biologically-active natural products.
Mycobacterial viability is dependent upon the ability of the organism to produce an intact cell wall. Therefore, compounds that interfere with the biosynthesis of the cell wall complex glycons have the potential to become new drugs for the treatment of mycobacterial infections. The oligosaccharide galactan is one of the major structural components of the outer wall of the micro-organism. Galactofuranose is essential for cell growth and survival and therefore, its biosynthesis constitutes a new drug target. The biosynthetic process involves several enzymes having Uridine-diphosphogalacto furanose (UDP-Galf) as the substrate; uridine 5^1 -diphosphogalacto pyranose mutase which catalyzes the interconversion of UDP galacatopyranose to UDP-galactofuranose as well as Galf-transferase. We are seeking and designing molecules that could be mechanistic probes and/or inhibitors of efflux pumps to potentially combat multidrug resistance.

 The isolation and structure-determination of six naturally occurring Flavan-type Natural products was performed. Such derivatives are known to reverse multiple-drug-resistance (MDR) in persistent microbial infections. The synthesis of pyrrolidine-based antibacterial agents was attempted using two different approaches from tartaric acid. These derivatives were designed as potential transition-state mimics of a carbohydrate processing enzyme specific to TB. A synthetic approach to the aromatic core structure of the antibacterial agent Platensimycin was also investigated. The synergistic use of cytotoxic agents in conjunction with efflux-pump modulators is an
emerging area of research in the MDR field; our efforts to make available materials for high-throughput screening in this area will be described.

abstract: Thesis

abstract: Master of Science (MSc)


title: How newspapers have represented the suburbs of Toronto and Hamilton since 1990

contributor:
Harris, Richard
Geography

subject: Suburbs Newspapers

abstract:
Much has been written about the public image of the suburbs, however very few
researchers have explored how they appear in the media. The purpose of this research is
to determine how local newspapers have represented the suburbs of Toronto and
Hamilton since 1990. The objective is to see whether there has been a historical shift in
the balance between positive and negative images, and also in the themes associated with
each. This has been done by examining articles from The Toronto Star and The Hamilton
Spectator. Articles from 1990-2015 were extracted using the online database, LexisNexis
Academic. These articles were then coded using a manual thematic coding scheme
accounting for several factors including the type of article, section of the newspaper,
front page material, centrality, valence, major themes, and neighbourhoods and regions
being discussed. NVivo software for qualitative data analysis was used to understand and
organize the abundance of unstructured data collected. As expected, the tone of coverage
in both cities was generally negative, but varied between cities and changed over time as
the mix of thematic concerns also changed.

abstract: Thesis

abstract: Master of Arts (MA)


title: Model Studies of Slag Metal Entrainment in Gas Stirred Ladles

contributor:
Irons, Gordon
Materials Science and Engineering

subject:
Slag metal entrainment
secondary steelmaking
Large Eddy Simulation
Synthetic Eddy Method
Gerris Flow Solver
RANS turbulence model

abstract:
In gas stirred steelmaking ladles, entrainment of slag into metal and vice versa takes place. The slag entrainment has been shown to abruptly increase the mass transfer rates of refining reactions through high temperature and water modeling studies of the past. However such an effect has not been correlated with the degree of entrainment, since the latter has not been quantified in terms of operating parameters like gas injection rate and fluid properties. Much of the past works are limited to finding the critical conditions for onset of entrainment. The difficulty lies in measuring the degree of entrainment in industrial ladles or even in a water model. Mathematical modeling is also challenging due to the complexity of the multiphase phenomena. So in this thesis, a modular mathematical modeling approach is presented wherein the phenomena of slag entrainment into metal is resolved into four aspects, models developed for each and finally integrated to study its role.
	The individual models are (1) multiphase large eddy simulations to simulate slag entrainment in a narrow domain that receives its boundary conditions from (2) single phase RANS simulation of a full ladle, (3) a Lagrangian particle tracking method to compute the residence times of slag droplets in metal phase and (4) a kinetic model that integrates the above three models to compute mass transfer rate as a function of degree of entrainment.
	Mass transfer rate predictions comparable to a literature correlation were obtained. This supports the modeling approach and also the assessment of role of various system parameters on entrainment characteristics. In essence, the present work shows a systematic approach to model and study the complex multiphase phenomena.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: The entrainment of liquid slag into liquid steel in gas stirred-steelmaking ladles is known to increase the rate of refining drastically. However, there is lack of correlation between degree of entrainment and ladle operating conditions, which this thesis addresses through mathematical modeling.


title: Atmospheric Transformation of Polycyclic Aromatic Compounds

contributor:
McCarry, B. E.
Chemistry

subject: atmospheric transformation, polycyclic aromatic compounds, NPAH, air samples, urban, rural sites

abstract:
 The profiles of polycyclic aromatic compounds (PAC) were compared in three separate studies involving air samples collected in urban and rural locations across Canada. In the Freelton/Pier 25 study (conducted near Hamilton, Ontario) a total of 32 NPAH were analyzed for in 12 composite air particulate samples from Freelton (a rural site) and Pier 25 (an urban site) using negative ion chemical ionization gas chromatography-mass spectrometry.

  The NPAH levels at the two sites were found to be similar except for the two samples at Pier 25. These results were consistent with the PAH levels determined previously which showed significantly increased levels at Pier 25 under the same condition when the sampling site was downwind of the urban/industrial core. NPAH may be significant contributors to mutation induction due to exposures to ambient air since the offspring of male mice from the Pier 25 site exposed to ambient air showed inherited mutation rates about 2 times greater than offspring of mice exposed at the Freelton site. NPAH are highly mutagenic and carcinogenic compounds that act via reductive metabolism and can be readily metabolized to potent reactive intermediates within all cells.

 Concentration data for a set of polycyclic aromatic compounds were obtained for samples collected during the day and night during a study in Simcoe (rural) and Toronto (urban) as well as at three sites in British Columbia as part of the Pacific 2001 study (Slocan (urban), Langley (suburban/rural) and Sumas (rural)). The conversion of these concentration data into particulate loadings data (using elemental carbon data) enabled us to perform a number of unique interpretations and analyses of the data sets. Since particulate loadings values are not affected by air dispersion it was possible to compare samples and individual PAC across a range of samples.

 Principal components analysis of the loadings data showed dramatic differences between the urban and rural sites from each study. Day-night samples at the rural sites also showed dramatic profile differences. The urban sites showed significantly less differences in profiles, consistent with lesser degree of air transformation and closer proximities to sources.

abstract: Thesis

abstract: Master of Science (MSc)


title: The Role of Glutamine:Fructose-6-Phosphate Amidotransferase and Protein Glycosylation in Hyperglycemia-Associated Endoplasmic Reticulum Stress

contributor:
Werstuck, Geoff H.
Biochemistry and Biomedical Sciences

subject: glutamine, fructose, phosphate, amidotransferase, protein glycosylation, hyperglycemia, endoplasmic reticulum stress

abstract:
 Diabetes mellitus is a major independent risk factor for cardiovascular disease (CVD) and stroke, however the cellular mechanisms by which diabetes contributes to vascular dysfunction are not fully understood. In recent decades, multiple molecular mechanisms have been implicated in hyperglycemia-associated vascular damage and CVD [1]. It is well established that hyperglycemia promotes intracellular glucose flux through the hexosamine pathway where the rate-limiting enzyme, glutamine:fructose-6-phosphate amidotransferase (GFAT) produces glucosamine-6-phosphate [2,3]. We have shown that elevated levels of intracellular glucosamine cause ER stress and activation of the UPR in multiple cell types [4]. Additionally, we have previously shown that ER stress is associated with lipid accumulation, activation of inflammatory pathways, and is associated with atherosclerotic plaque formation in hyperglycemic mice [ 4,5]. We hypothesize that the accumulation of intracellular glucosamine, observed in conditions of hyperglycemia, promotes atherogenesis via a mechanism that involves the hexosamine pathway, protein glycosylation and ER stress.

 Using in vitro over-expression studies, we investigated the role of GFAT in hyperglycemia-associated ER stress. We developed methods to increase GFAT expression in both HepG2 cells and HASMC. However, we found that GFAT over-expression is insufficient to induce an ER stress response. Further investigation of this system suggests that the over-expressed GFAT does not increase intracellular glucosamine levels to sufficiently promote ER stress.

 We have also investigated the role of protein glycosylation in glucosamine-induced ER stress. We have shown that O-linked glycosylation plays a role in ER stress induction. We have also shown that N-linked protein glycosylation is affected by elevated cellular glucosamine levels. Thus, dysregulated glycosylation of newly synthesized proteins may contribute to the accumulation of unfolded protein in the ER and lead to the activation of the UPR.

abstract: Thesis

abstract: Master of Science (MSc)


title: Modulation of Human Melatonin MT1 Receptor By Valproic Acid and its Effects in Combination with Melatonin on Human Breast Cancer

contributor:
Niles, Len
Biochemistry and Biomedical Sciences

subject: modulation, human melatonin MT1 receptor, valproic acid, human breast cancer, oncostatic, gene

abstract:
 The MT1 receptor is involved in the oncostatic action of melatonin and valproic acid (VPA) in human MCF-7 breast cancer cells and VPA can upregulate this receptor in C6 glioma cells. Therefore, the effect of VPA on the expression of the MT1 was examined in MCF-7 cells. Treatment of MCF-7 cells in low serum conditions with VPA (0.5 or 1mM) for 24 or 72 h caused a significant increase in MT1 receptor expression, as shown by reverse transcription-polymerase chain reaction analysis (RT-PCR). MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assays performed in high serum conditions revealed a significant concentration-dependent inhibition of MCF-7 cell proliferation by VPA (0.5 - 5 mM), whereas melatonin (1 or 10 nM) showed modest effects alone. However, a combination of VPA and melatonin produced a marked synergistic inhibition of cell proliferation. In subsequent experiments, under high serum conditions, VPA treatment for 24h on these cells resulted in a significant decline of MT1 mRNA while the protein levels were still increasing, as seen by RT-PCR and western blotting respectively. The involvement of multiple biochemical events, such as: induction of the p53 tumor suppressor gene and repression of the estrogen receptor (ER)-alpha might be responsible for the synergistic inhibition of these cells after the simultaneous
exposure to VPA and melatonin. These results indicate that clinically relevant concentrations of VPA upregulate melatonin MT1 receptor expression in human breast cancer cells. Moreover, the enhanced antiproliferative effect observed with a combination of VPA and melatonin suggests that a similar therapeutic approach may be beneficial in human breast cancer.

abstract: Thesis

abstract: Master of Science (MSc)


title: Numerical modeling of localized damage in plain and reinforced concrete structure

contributor:
Pietruszczak, Stanislaw
Civil Engineering

subject:
Volume averaging technique
3D Crack Propagation
Chemo-Mechanical modeling
Reinforced concrete

abstract:
The primary objective of this research is to develop and verify a methodology for modeling three dimensional discrete crack growth in concrete and reinforced concrete structures. Two main sources of damage, considered in this work, include the mechanical loading and the chemical interaction. The behavior of concrete is brittle in tension and becomes ductile behavior under compressive loading. At the same time, the chemical interaction triggers a progressive degradation of strength parameters. The main focus in this research is on numerical analysis of localized damage that is associated with formation of macrocracks. The specific form of chemical interaction examined here involves the alkali-silica reaction (ASR).
The approach used in this work for describing the propagation of macrocraks is based on the
volume averaging technique. This scheme represents a simplified form of strong discontinuity
approach (SDA). It incorporates the notion of a ‘characteristic length’, which is defined as the
ratio of area of the crack surface to the considered referential volume. It is demonstrated, based on an extensive numerical study, that this approach gives mesh-independent results which are consistent with the experimental evidence. The accuracy of the solutions is virtually the same as that based on SDA and/or the Extended Finite Element Method (XFEM), while the computational effort is significantly smaller. In order to describe the behavior of the fractured zone, a traction velocity discontinuity relation is formulated that is representative of different modes of damage
propagation, including crack opening in tensile regime as well as shear band formation under
compression. For tracing the discontinuity within domain, crack smoothening algorithm is
employed to overcome any numerical instabilities that may occur close to ultimate load of the
structure.
The general methodology, as outlined above, has been enhanced by incorporating the chemoplasticity framework to describe the damage propagation in concrete affected by chemical interaction, i.e. continuing ASR. The latter is associated with progressive expansion of the silica gel that is coupled with degradation of strength properties. An implicit scheme has been developed, incorporating the return mapping algorithm, for the integration of the governing constitutive relations. The framework has been implemented in Abaqus software to examine the crack propagation pattern in structural elements subjected to continuing ASR.
Another major topic addressed in this thesis is the ‘size effect’ phenomenon. The existing
experimental studies, conducted primarily on various concrete structures, clearly show that the ultimate strength is strongly affected by the size of the structure. This phenomenon stems primarily from the effect of localized damage that accompanies the structural failure. The quantitative response depends on the geometry of the structure, type of loading and the material properties. The size effect has been investigated here for a number of notched and un-notched concrete beams, of different geometries, subjected to three-point bending. Both mechanical loading and the chemical interaction have been considered.
The next topic considered in this study deals with analysis of localized fracture in 3D reinforced concrete structures. Here, a mesoscale approach is employed whereby the material is perceived as a composite medium comprising two constituents, i.e. concrete matrix and steel reinforcement. The response at the macroscale is obtained via a homogenization procedure that incorporates again the volume averaging. The latter incorporates a set of static and kinematic constraints that are representative of the response prior to the onset of fracture. After the formation of macrocracks, a traction-separation law within the fractured zone is modified by incorporating the Timoshenko beam theory in order to assess the stiffness characteristics in the presence of reinforcement. A number of numerical examples are given that examine the crack pattern formation and the associated fracture mechanism in concrete beams at different intensity of reinforcement.
The final chapter of this thesis provides an illustrative example of the application of the proposed methodology to the analysis of a large scale structure. The focus here is on the assessment of structural damage in a hydraulic structure subjected to ASR continuing over of period of a few decades. The results, in term of the predicted extent of damage as well as the displacement history at some specific locations, are compared with in-situ monitoring.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Exploring and expanding stakeholders’ perspectives on the management of Cerebral Palsy, using the International Classification of Functioning, Disability and Health (ICF) and Knowledge Translation framework

contributor:
MacDermid, Joy
Rehabilitation Science

subject:
Cerebral Palsy
ICF
Knowledge Translation
Perspectives

abstract:
Introduction: Cerebral Palsy (CP) is the most common cause of disability in children.
Healthcare providers aim to facilitate optimal function and participation by working with
children and their families. The success of this endeavor depends on shared understanding,
collaboration, and contextual factors that affect resource availability. The aim of this thesis was
to understand parents’ perspectives in Indian and North American cultures towards management
of CP using an ICF lens, to evaluate the extent to which this lens is evident in literature
conducted in an Indian context and to evaluate a Knowledge Translation (KT) resource to inform
parents and healthcare professionals (HCP).
Methods: In the five thesis papers: study 1 explored parents’ perspectives towards the
management of their children with CP (qualitative design); study 2 described the contextual
factors shaping parents’ perspective in India (reflective design); study 3 and 4, described the
research trends in the management of CP in India (scoping review); and study 5 describes the
development and evaluation of a KT resource created to inform parents about incorporating the
ICFconcepts into management of CP.
Results: The qualitative study identified that Indian parents focus more on Body Structure and
Function (BSF) challenges and have more resource limitations, as compared to the Canadian
context. The scoping review identified that research also focuses on BSF, with less research
addressing activity and participation, or its environmental determinants. KT resources showing
the application of the ICF concepts into CP management received widespread uptake and were
perceived as helpful by parents and HCP.
Discussion and Conclusion: ICF was useful for understanding and informing parents and HCP
about management of CP. Despite the importance of environmental considerations and
contextual factors, these were insufficiently addressed in the literature and in stakeholder
perspectives. To optimize CP management across contexts, further research and KT is needed.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract:
Cerebral Palsy (CP) is the most common cause of physical disability in children. Parents and
professionals from multiple disciplines work together to provide developmental support for
children with CP. This thesis explored parents’ views about management of CP in India and
Canada; assessed the scope of the scientific literature from India addressing CP; and developed
and evaluated educational videos to inform parents and professionals about the use of the
International Classification of Functioning, Disability and Health (ICF) in the management of
CP. Parents’ views towards their children in both countries are influenced by the availability of
resources, professional attitudes, and cultural beliefs. Research in India focuses on ‘fixing’ the
child’s impairments. The videos developed to encourage parents and doctors to focus on
increasing activity and participation in children, were judged to be useful in creating awareness about the use of the ICF in the management of CP.


title: Conducting Polymer-based Electrodes for Electrochemical Supercapacitors

contributor:
Zhitomirsky, Igor
Materials Science and Engineering

abstract:
Electrochemical Supercapacitors (ESs) have been under investigation for decades as advanced energy storage devices. Selection and fabrication of electrode materials are of vital importance for ESs in terms of energy density, power density, cycling stability, specific capacitance, impedance and other capacitive properties. Among various kinds of materials that can be used for electrode fabrication for ES, Polypyrrole (PPy) is found to be promising due to high specific capacitance, high electric conductivity and low cost of fabrication of this material. The addition of advanced anionic dopant enables higher electric conductivity and the combination of PPy and multiwalled carbon nanotubes (MWCNT) enhances cycling stability of polymer backbone during testing process, which improves capacitive behavior of PPy and the composite materials. Since MWCNT has a relatively high aspect ratio making it difficult to be well dispersed, the selection of effective dispersing agents and dispersion of MWCNT consist an important part of this research.
In this research, PPy and PPy/MWCNT composite materials were synthesized both in chemical and electrochemical ways. The anionic dopants included 4, 5-Dihydroxy-1, 3-benzenedisulfonic acid disodium salt monohydrate (Tiron) and 4-Formylbenzene-1,
i
M.A.Sc Thesis Jieming Li McMaster University Materials Science and Engineering
3-disulfonic acid disodium salt hydrate (FDS). And also three kinds of multifunctional dopants were used, that can act as dopant for PPy and dispersing agent for MWCNT at the same time, including Eriochrome Cyanine R (ECR), 4-Amino-5-hydroxy-2, 7-naphthalenedisulfonic acid monosodium salt hydrate (AHN) and 3-Hydroxy-4-nitroso-2, 7-naphthalenedisulfonic acid disodium salt (HNN). The molecular size and functional groups of the anionic dopants and dispersants have great influence on the morphology and capacitive properties of PPy and PPy/MWCNT composites. Higher specific capacitance and excellent capacitance retention were achieved by chemical synthesis, which also offers advantages for large scale production.
The results showed that with dopants possessing larger molecular size and multiple charged groups, smaller particle size of PPy and improved capacitive properties could be obtained. The PPy/MWCNT mass ratio of 7 to 3 and Py monomer to dopant molecule molar ratio of 3 to 1 were found to be optimal. The use of Ni foam current collector enabled high mass loading of active materials, which facilitates the fabrication of advanced electrodes for supercapacitors.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Nth Order Self Adapting Control Systems

contributor:
Sinha, N. K.
Electrical Engineering

subject: nth order, self adapting, control systems, vector cost function

abstract:
 The very sophisticated control systems of today are built around computers. It is felt
that an improved form of cost function in vector or matrix form is needed to fully and most easily utilize the computer's advantages. After defining a vector cost function G , the problem of adapting and learning simplifies to the solution of a partial difference equation. Total system properties are easily defined as matrix arrays which are "learned" in an adapting and "learning" control loop.

 The relative merits of open and closed loop adaptive
systems were investigated. The Nth order adaptive control system was finally chosen to be closed loop after developing two criterion equations in two unknowns which, if satisfied guaranteed improved system sensitivity with the closed loop configuration.

 Finally, several simple examples are given in experiment form to demonstrate the applicability of the
proposed control system techniques.

abstract: Thesis

abstract: Master of Engineering (MEngr)


title: Ophthalmic Biomaterials

contributor:
Sheardown, Heather
Biomedical Engineering

subject:
Biomaterials
Ophthalmology
cell delivery
cell scaffold
drug delivery
mucoadhesive

abstract: This thesis will explore, both generally and very specifically, the role of biomaterials in drug delivery and tissue engineering applications. A novel therapeutic conjugate to treat dry eye disease using hyaluronic acid and sulfadiazine was created and tested using a benzalkonium chloride induced dry eye model. Thermoresponsive hydrogels based around poly(n-isopropylacrylamide) were synthesized to create a potential in situ gelling cell scaffold for cell delivery to the subretinal space. Finally, a mucoadhesive micelle was developed as a platform delivery system to increase bioavailability of drug in anterior segment therapeutics.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: SYNTHESIS AND CHARACTERIZATION OF MAGNETIC CARBON NANOTUBES

contributor:
Puri, Ishwar K.
Engineering Physics

subject:
Carbon nanotubes
Functionalization
Nanofluid
Magnetic nanoparticles
Electroless deposition
Co-precipitation
Bioinks
Biosensors
Nickel oxide nanotubes
Supercapacitor

abstract: The superior properties of carbon nanotubes (CNTs) are best manifest in bulk materials when the CNTs are organized in tandem and embedded in a continuous matrix. Decorating the CNTs with magnetic nanoparticles (MNPs) facilitates their expedient organization with a magnetic field. One of the most convenient methods for their decoration is to first treat the CNTs with oxidative acids, and then coprecipitated MNPs in situ. This method results magnetized CNTs that are covalently functionalized with the MNPs. The associated destruction in the CNTs required running a comparative study of this protocol to identify the influence of the acid treatment on the decoration of multiwalled CNTs (MWNTs). Further, we explore means to tune the physical properties of these magnetized CNTs (mMWNTs) by varying the (1) MNP material composition, and (2) MNP:MWNT (w/w) magnetization weight ratio (γ). The resulted composite materials (mMWNTs) are utilized to synthesize a novel and hitherto unreported class of colloidal suspensions (MCCs) for which the dispersed phase, which consists of MWNTs decorated with MNPs, is both magnetoresponsive and electrically conductive. Synthesis of the dispersed phase merges processes for producing ferrofluids and mMWNTs. Later, these MCCs are adapted and engineered to produce a biological ink containing MWNTs that are twice functionalized, first with MNPs and thereafter with the anti-c-Myc monoclonal antibodies (Abs). The ink is pipetted and dynamically self-organized by an external magnetic field into a dense electrically conducting sensor strip that measures the decrease in current when a sample containing c-Myc antigens (Ags) is deposited on it. On the other side, a nondestructive methods to magnetize MWNTs and provide a means to remotely manipulate them is through the electroless deposition of magnetic nickel nanoparticles on their surfaces. The noncovalent bonds between Ni nanoparticles and MWNTs produce a Ni-MWNT hybrid material (NiCH) that is electrically conductive and has an enhanced magnetic susceptibility and elastic modulus. Raising γ (Ni:MWNT weight ratios) increases the coating layer thickness, which influences the NiCH magnetic properties and tunes its elastic modulus. The NiCH was used to fabricate Ni-MWNT macrostructures and tune their morphologies by changing the direction of an applied magnetic field. Leveraging the hydrophilic Ni-MWNT outer surface, a water-based conductive ink was created and used to print a conductive path that had an electrical resistivity of 5.9 Ωm, illustrating the potential of this material for printing electronic circuits. Further, the NiCHs are introduced into an epoxy matrix at low 0.25-1% volume fractions and aligned along the direction of an applied magnetic field, which produces anisotropic bulk properties. However, nanoparticles aligned in perpendicular directions in sequential layers result in an effectively isotropic composite material. Furthermore, the subsequent annealing of the NiCH in the presence of air oxidizes nickel to nickel oxide whereas carbon is released as gaseous carbon dioxide, which leads to a novel approach for the fabrication of nickel oxide nanotubes (NiONTs) based on MWNTs as a sacrificial template. New chelating polyelectrolytes are used as dispersing agents to achieve high colloidal stability both for NiCH and NiONTs. A gravimetric specific capacitance of 245.3 F g-1 and areal capacitance of 3.28 F cm-2 at a scan rate of 2 mV s-1 is achieved with an electrode fabricated using nickel oxide nanotubes as the active element with a mass loading of 24.1 mg/cm2.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: The superior properties of carbon nanotubes (CNTs) are best manifested in bulk materials when the CNTs are organized axially and in tandem, and embedded in a continuous matrix. Decorating the CNTs with magnetic nanoparticles (MNPs) facilitates their organization through “action from a distance” with a magnetic field. The attachment of MNPs to the surfaces of CNTs can be realized through covalent or non-covalent (i.e. physical) bonding. This work develops both methodologies to investigate how the physical properties of magnetized CNT (mCNT) can be tuned and produce new CNT-based nanostructures for particular applications. First, mCNTs are utilized to synthesize a hitherto unreported class of colloidal suspensions based on which a magnetic bio-ink is fabricated to print a fast-response biological sensor. Next, nickel-coated CNTs prepared using electroless deposition are used in the form of a filler at low volume fractions in an epoxy matrix, where they are aligned along multiple-direction using a magnetic field, producing either anisotropic or isotropic bulk properties on demand. Finally, subsequent annealing of nickel-coated CNTs in air oxidizes nickel to nickel oxide while carbon is released in the form of gaseous carbon dioxide. This leads to another novel approach for the fabrication of nickel oxide nanotubes, which are demonstrated to be an alternate viable material to fabricate electrodes for use in supercapacitors.


title: Singularities in a BEC in a double well potential

contributor:
O'Dell, Duncan
Physics and Astronomy

subject:
quantum
phase transition
catastrophe theory
many-body systems

abstract:
This thesis explores the eﬀects singularities have on stationary and dynamical properties of many-body quantum systems. In papers I and II we ﬁnd that the ground
state suﬀers a Z2 symmetry breaking phase transition (PT) when a single impurity
is added to a Bose-Einstein condensate (BEC) in a double well (bosonic Josephson
junction). The PT occurs for a certain value of the BEC-impurity interaction energy,
Λc . A result of the PT is the mean-ﬁeld dynamics undergo chaotic motion in phase
space once the symmetry is broken. We determine the critical scaling exponents that
characterize the divergence of the correlation length and ﬁdelity susceptibility at the
PT, ﬁnding that the BEC-impurity system belongs to the same universality class as
the Dicke and Lipkin-Meshkov-Glick models (which also describe symmetry breaking
PTs in systems of bosons).
In paper III we study the dynamics of a generic two-mode quantum ﬁeld following a
quench where one of the terms in the Hamiltonian is ﬂashed on and oﬀ. This model is
relevant to BECs in double wells as well as other simple many-particle systems found
in quantum optics and optomechanics. We ﬁnd that when plotted in Fock-space plus
time, the semiclassical wave function develops prominent cusp-shaped structures after
the quench. These structures are singular in the classical limit and we identify them
as catastrophes (as described by the Thom-Arnold catastrophe theory) and show that
they arise from the coalescence of classical (mean-ﬁeld) trajectories in a path integral
description. Furthermore, close to the cusp the wave function obeys a remarkable set
of scaling relations signifying these structures as examples of universality in quantum
dynamics. Within the cusp we ﬁnd a network of vortex-antivortex pairs which are
phase singularities caused by interference. When the mean-ﬁeld Hamiltonian displays
a Z2 symmetry breaking PT modelled by the Landau theory of PTs we calculate
scaling exponents describing how the separation distance between the members of
each pair diverges as the PT is approached. We also ﬁnd that the cusp becomes
inﬁnitely stretched out at the PT due to critical slowing down.
In paper IV we investigate in greater detail the morphology of the vortex network
found within cusp catastrophes in many-body wave functions following a quench. In
contrast to the cusp catastrophes studied so far in the literature, these structures live
in Fock space which is fundamentally granular. As such, these cusps represent a new
iii
type of catastrophe, which we term a ‘quantum catastrophe’. The granularity of Fock
space introduces a new length scale, the quantum length lq = N −1 which eﬀectively
removes the vortex cores. Nevertheless, a subset of the vortices persist as phase
singularities as can be shown by integrating the phase of the wave function around
circuits in Fock-space plus time. Whether or not the vortices survive in a quantum
catastrophe is governed by the separation of the vortex-antivortex pairs lv ∝ N −3/4
in comparison to lq , i.e. they survive if lv
lq . When particle numbers are reached
such that lq ≈ lv the vortices annihilate in pairs.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: GEANT4 Simulations and Experimental Tests of a Silicon CD Detector

contributor:
Chen, Alan
Physics and Astronomy

subject: GEANT4, simulations, experimental tests, Silicon CD detector, unstable nuclei, TRIUMF-ISAC, excitation

abstract:
 In nuclear astrophysics, there are still undiscovered areas involving unstable nuclei, like the nucleosynthesis in exploding stars. The unstable nuclei are extremely difficult to produce in the laboratory for study since they decay away quickly once they are formed. To make the unstable nuclei available in the laboratory, Canada has built one of the best facilities in the world for nuclear astrophysics studies with radioactive beams, called TRIUMF-ISAC. Its recent upgrade to ISAC-2 can produce even heavier radioactive beams with higher energy. To fully utilize the ISAC-2 facility, a high-segmented HPGe γ-ray detector-TIGRESS, has been
developed to study exotic nuclei using the well-established technique of Coulomb Excitation.

 As an essential part of the TIGRESS facility, auxiliary detectors, such as silicon
detectors, are used to improve the sensitivity of the experiments through Doppler correction. Two types of silicon detectors will be used. One is the CD-shaped double-sided silicon strip detector, which is the topic of this thesis. The other one is the silicon barrel detector. This thesis will discuss the computer simulations and experimental tests of the CD detector.

 Simulations were made using a simulation toolkit GEANT4, which was run under the Linux system. The goal was to test the hypothesis that measurements of the energies of heavy ions in Coulomb excitation may improve the Doppler correction by constraining the scattering location in a thick target. To test the performance of the simulated CD detector, simple simulations were performed for shooting calibration alpha particles from an 241Am source first directly onto the CD and second through a thin target onto the CD. The goal of additional simulations was to attempt to determine the corresponding scattering depth in a thick target by putting an energy cut on the spectrum of the scattered beam detected in the
CD. These simulation results verify the possibility of such localization, though the resolution is not very good.

 Experimental tests for the CD detector are aimed to obtain the energy resolution for each strip element of the CD and to have at least 8 channels instrumented in our test lab before this detector is sent to TIGRESS facility. The test station
including electronics and detector systems and all results from initial tests are described in detail in this thesis.

abstract: Thesis

abstract: Master of Science (MSc)


title: The Implications of Multiple Stellar Formation Events for the Evolution of Globular Clusters

contributor:
Sills, Alison
Physics and Astronomy

subject: implications of multiple stellar formation events, evolution, globular clusters, second generation, Salpeter IMF

abstract:
 In this thesis we investigate the dynamical effect of a second generation of stellar formation in globular clusters in the context of the anomalous horizontal branch of NGC 2808. The horizontal branch of NGC 2808 is bifurcated in colour and exhibits an extended blue tail. This morphology can be explained if the blue tail stars have an enhanced helium content due to cluster self-enrichment. Specifically it has been proposed that NGC 2808 has experienced
two distinct generations of star formation. The first generation has a top-heavy IMF, enhanced in 3 - 5Mo stars, and would produce many AGB stars within the first 200 Myrs of its life. The second generation then forms out of the helium-rich ejecta of the AGB stars and goes on to produce the blue tail in the horizontal branch that is currently observed in NGC 2808.

 We use three types of simulations to investigate this scenario. For a control model we run a simulation with a Salpeter IMF and a single generation. We then run models with a top-heavy IMF and a single generation and models with a top-heavy IMF and two generations. In the two generation models we also investigate the effect of concentration by examining simulations with two different length scales.

 We find that the models with the top-heavy IMF and a single generation are subject to extensive mass-loss in their early phases due to the large number of intermediate-mass stars and are less strongly affected by two-body
relaxation than simulations with a Salpeter IMF. The models with two generations appear to be dynamically stable and long-lived objects, at least in their early stages. They seem to be observationally indistinguishable from single-generation clusters with Salpeter IMFs on the basis of their dynamics. The stellar populations of the two-generation clusters are found to have a much higher fraction of C-O white dwarfs than clusters with a Salpeter IMF. We find no evidence that these bodies will be preferentially scattered out of the system and they should remain part of the cluster until it dissolves after core collapse. The abundance of white dwarfs would provide an observational method of identifying two generation cluster candidates.

 Overall we find the two-generation scenario to be plausible on the basis of dynamics but due to the overabundance of white dwarfs produced by the top-heavy IMF and based on other studies of the chemistry of AGB stars we conclude that this scenario is unlikely to be the sole explanation for globular cluster self-enrichment.

abstract: Thesis

abstract: Master of Science (MSc)