title: SHUNT ACTIVE POWER FILTERING FOR SMART APPLIANCES

contributor:
Al-Mutawaly, Nafia
Schofield, Nigel
Electrical and Computer Engineering

subject: Power Quality, Power Systems, Power Electronics, Control.

abstract: Due to the increasing trend towards energy saving of white goods appliances and the commercial viability of power electronic components, there has been an expansion in the use of solid state electronics and variable frequency drive motors in these applications. However, a major drawback of using such energy efficient loads is the introduction of current harmonics onto the local distribution grid. Furthermore, the proliferation of such devices elevates the harmonic content of the supply voltage and the ensuing potential impact on residential distribution networks. This thesis investigates the harmonic content generated by some representative household appliances and suggests a solution to minimize current harmonics by means of active filtering.  An active filter circuit is proposed and simulations will be undertaken to compare filter performance when used as an active front end versus a feeder input compensator. Further, a hardware design of the filter was implemented to experimentally verify the filter operation.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: MOTIVATION AND DEMOTIVATION OF HACKERS  IN THE SELECTION OF A HACKING TASK  – A CONTEXTUAL APPROACH

contributor:
Head, Milena
Business Administration

subject: Hackers security Motivation

abstract:
This research explores hacker motivation, demotivation and task selection through the lenses of the Theory of Reasoned Action (TRA) and General Deterrence Theory (GDT). The research also explores how context surrounding individual and task characteristics affects a hacker’s decision making process in selecting a hacking task. To build a solid foundation on which to understand and combat threats to information systems, researchers need to look past the technical issues of data security and explore why hackers do what they do. This research addresses this gap by understanding why hackers identify and assess hacking tasks. It is hoped that by investigating the motivations of these highly skilled Information Systems (IS) users, new insights into how to avoid becoming a hacker target might be developed.
Participants in this study were individuals who self-identify as hackers. They completed a survey to validate the proposed model and answered open-ended questions to provide further insights. The quantitative data was analysed using Structured Equation Modelling; classical content analysis was conducted to examine the qualitative data.
This research was successful in identifying the role of TRA and GDT in hacker task selection. The research confirmed the importance of mastery, curiosity, and task complexity in a hacker's evaluation process and provided enticing clues for further research into the role of task complexity in a hacker’s task evaluation process. The research also confirmed that subjective norms play an important part in shaping behavioural intentions towards engaging in a hacking task. Additionally, a clear linkage was identified between perceived certainty of sanction and behavioural intention. Contributions of this research to both academia and practice are outlined as well as potential limitations and areas for future research.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)


title: Development of the next-generation of dewatering technologies for mature fine tailings (MFTs) from oil sands processing

contributor:
Latulippe, David
Chemical Engineering

subject: MFT

abstract: The oil sands industry is currently facing a challenge by regulators to develop dewatering technologies that can halt any further growth in the massive size of existing tailings ponds and also reclaim the contents of those ponds. The most recent technology involves in-tank and/or in-line addition of flocculants followed by a dewatering step (e.g. centrifugation, thin-lift dewatering). This work has focused on three different dewatering technologies. Firstly, a high-throughput method was developed to investigate the effects of ionic composition adjustment on MFTs dewatering through a centrifugation process. As a result, it was found that samples with different concentrations and valency of cations had different settling kinetic and higher concentrations and valency of cations caused faster settling. Also, changes in the ionic composition of samples suggest that there is a strong interaction (ion exchanging) between MFTs and added solution. Secondly, the effects of different factors (e.g. freezing time and temperature) on freeze-thaw dewatering of MFTs were studied using a temperature monitoring setup. It was found that partial freezing causes less dewatering compared to complete freezing after thawing. Finally, a lab-scale unit of low-speed rotary filtration was built and it was implemented to dewater polymer amended MFTs. By using this unit, effects of different factors were investigated on the dewatering efficiency of the rotary filtration unit through a DOE study. The DOE results showed that the flocculation conditions have a big impact on performance of the rotary filtration and for some of the DOE conditions, cakes were formed with more than 47 wt% which couldn’t be reached by just gravity settling of polymer amended MFTs. Also, freeze-thaw of the cakes after rotary filtration could increase the solids content.

abstract: Thesis

abstract: Master of Applied Science (MASc)

abstract: The oil sands industry has been challenged by regulators to develop dewatering technologies that can stop any further growth in the massive size of existing tailings ponds and also reclaim the contents of those ponds. The current dewatering technologies have different challenges that were tried to address in this study. At the first part of the research, it was tried to develop a method for rapid investigation of the effects of salt addition followed by a mechanical method (centrifugation) on dewaterability of MFTs. In the second part it was tried to investigate freeze-thaw as a natural dewatering technique and also to investigate the possibility of mechanizing this process. In the last part, an alternative dewatering technology (rotary filtration), that is predicted to be cheaper than centrifugation, was used to dewater MFTs (amended by polymer). Therefore, a lab-scale version was made and used for polymer amended MFTs dewatering. By using this technology the solids content of MFT had around 20 wt% increase (compare to the untreated MFTs).


title: An Almost Everywhere Extension Theorem for Continuous Definable Functions in an O-minimal Structure

contributor:
Speissegger, Patrick
Mathematics and Statistics

abstract: Let $\mathcal{R} = (R, <, \mathcal{S})$ be an o-minimal expansion of an ordered group. In this thesis, we define the class $\mathcal{C}$ of asymptotically monotone cells and we show they have the property that, for any cell $C \in \mathcal{C}$ and for any definable, continuous, bounded function $f : C \rightarrow R$, it is always possible to continuously extend $f$ "almost everywhere" to the frontier of $C$. We make this notion precise using a theory of dimension for sets definable in an o-minimal structure. This result is a generalization of a known fact about continuous extensions of definable, continuous, bounded functions on open cells; we show by way of counterexample that the original result does not generalize to the class of all cells and hence that the assumption that our cells are asymptotically monotone is required. Background on o-minimality and the theory of dimension for definable sets is provided.

abstract: Thesis

abstract: Master of Science (MSc)


title: Effects of copper on the acute ventilatory drive of killifish, Fundulus heteroclitus

contributor:
McClelland, Grant B
Biology

subject: Copper Hypoxia Aquatic Toxicology Ventilation Morphometry Immunohistochemistry Fish

abstract: Organisms are often exposed to multiple stressors in their natural habitat. While the effects of individual stressors alone are generally well-studied, their combined interactions are often unknown. One such unknown interaction is that between copper, an essential micronutrient that is toxic in high levels, and hypoxia, a commonly experienced environmental stressor. This project sought to examine the effects that copper has on the hypoxic response as well as the combined effects of copper and hypoxia exposure using freshwater-acclimated adult killifish (Fundulus heteroclitus), a model euryhaline teleost. It was found that copper blunts the acute ventilatory response to hypoxia, ammonia, and combined hypoxia and ammonia exposure. Gill morphometry was also examined and it was found that while copper alone has no effect, when combined with hypoxia exposure it eliminates the increase in filament length and cross-sectional area seen when fish were exposed to hypoxia alone. Furthermore, when neuroepithelial cell size was examined, copper decreased cell projection area with or without the combined presence of hypoxia. Taken as a whole, this thesis indicates that copper exposure can significantly and negatively impact the ability of aquatic organisms to mount appropriate physiological responses to hypoxia.

abstract: Thesis

abstract: Master of Science (MSc)


title: Numerical Study of The Dynamical Casimir Effect and its Classical Analogue in a Double Cavity

contributor:
O'Dell, Duncan H J
Physics and Astronomy

subject: Dynamical Casimir Effect, Double Cavity

abstract:
We study the time evolution of light fields inside a double cavity which is comprised of two perfect end mirrors and a parametrically driven, partially transmissive central mirror in both a classical and a quantum mechanical framework. It is common practise in the field of optomechanics to take a Hamiltonian approach \cite{aspelmeyer2014cavity} ignoring non-linear coupling terms between the light field and the moving mechanical element. By contrast, we start from the Maxwell wave equation which is second order in time and find that a first order in time Schr\"{o}dinger-type wave equation (equivalent to neglecting the non-linear coupling) is a valid approximation for low enough mirror reflectivity and speed and for large light frequencies. We also study adiabatic dynamics for the Maxwell wave equation and find it differs from the more familiar adiabaticity in the Schr\"{o}dinger equation.

Next, we numerically simulate the dynamical Casimir effect (DCE) in the double cavity with a sinusoidally driven central mirror following earlier numerical work on the perfect single cavity \cite{Ruser2006NumericalDCE,ruser2005vibrating,naylor2009dynamical}. Because our central mirror is partially transmissive it is physically more realistic and circumvents fundamental problems associated with having perfectly reflecting moving mirrors \cite{Moore1970DCESingleCavity,barton1993quantum}. The corresponding photon creation rates are drastically lower when compared to the perfectly reflective mirror case. Furthermore, if we make one of the cavities much longer than the other we can simulate the DCE for a single open cavity coupled to an environment without having to make the Markov approximation. The resultant asymmetric double cavity (ADC) model is valid for times short enough that only a negligible number of the photons that has leaked out of the open cavity has sloshed back in again. As for the symmetric case, one advantage of the ADC is that driven mirror is partially transmissive rather than perfectly reflecting.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: FACTORS INFLUENCING PREGNANT AND PARENTING YOUNG WOMEN’S SMOKING BEHAVIOUR: AN INTERPRETIVE DESCRIPTIVE STUDY

contributor:
Sword, Wendy
Kurtz Landy, Christine
Butt, Michelle
Nursing

subject:
pregnant and parenting young women
smoking behaviours
personal and contextual factors
smoking cessation strategies
nursing
qualitative research
social determinants of health
voices of young women

abstract: Pregnant and parenting young women rarely access community-based smoking cessation interventions. Targeted cessation interventions have been laden with challenges and have produced suboptimal outcomes. There is a paucity of qualitative research specific to young women that explores the context of their tobacco use, as well as their attitudes towards and experiences with smoking cessation supports in pregnancy and postpartum. To bridge this gap, an interpretive descriptive design was used to explore the personal and contextual factors influencing young women’s smoking behaviour during and after pregnancy. Factors were identified by analyzing influences at the multiple levels of McLeroy’s social ecological model of health promotion. Data were collected via in-depth, semi-structured interviews with young women aged 16-24 years (n=13) who smoked regularly preconception and were pregnant or parenting. Transcripts were analyzed using qualitative content analysis. Findings highlighted the complexity and chronicity of issues young women faced and emphasized the interplay of social determinants that influenced their smoking. Smoking was a crutch that helped them to relieve psychological distress stemming from exposure to adverse or traumatic experiences; and persistent stress in the context of socioeconomic hardship, neighborhood disadvantage and limited social support. Smoking also was influenced by young women’s understanding of the harms related to smoking during pregnancy and their reconceptualization of risk for smoking-related consequences postpartum. Young women described having limited discussions regarding smoking with maternity care providers and found their passive approach to cessation counselling unhelpful. They desired more comprehensive cessation support from providers. They expressed interest in a tailored group cessation program and offered suggestions for improving cessation supports for young women in pregnancy and postpartum. Study findings bridge gaps in the literature and identify appropriate next steps in addressing the issue of smoking in pregnancy and postpartum amongst young women by suggesting a multi-level approach to cessation.

abstract: Thesis

abstract: Master of Science (MSc)


title: Study of the Seismic Response of Unanchored Equipment and Contents in Fixed-Base and Base-Isolated Buildings

contributor:
Konstantinidis, Dimitrios
Civil Engineering

subject: Nonstructural Components, Base-Isolation, Shake Table Test, Medical Equipment, Hospital, Unanchored Contents, Sliding, Stick-Slip, Wheels and Casters, Fragility Curve, Vision-Based Measurement, Non-contact Measurement

abstract:
Immediate occupancy and functionality of critical facilities including hospitals, emergency operations centers, communications centers, and police and fire stations is of utmost importance immediately after a damaging earthquake, as they must continue to provide fundamental health, emergency, and security services in the aftermath of an extreme event. Although recent earthquakes have proven the acceptable performance of the structural system in such buildings, when designed according to recent seismic design codes, in many cases damage to the nonstructural components and systems was the main cause of disruption in their functionality.
Seismic isolation is proven to be an effective technique to protect building structures from damaging earthquakes. It has been the method of choice for critical facilities, including hospitals in Japan and the United States in recent years. Seismic isolation appears to be an ideal solution for protecting the nonstructural components as well. While this claim was made three decades ago, the supporting research for freestanding (unanchored) equipment and contents (EC) is fairly new.
With the focus on freestanding EC, this study investigates the seismic performance of sliding and wheel/caster-supported EC in fixed-base and base-isolated buildings. The study adopts a comparative approach to provide a better understanding of the advantages and disadvantages of using each structural system. The seismic response of sliding EC is investigated analytically in the first part of the thesis, while the response of EC supported on wheels/casters is examined through shake table experiments on two pieces of hospital equipment.
The study finds base isolation to be generally effective in reducing seismic demands on freestanding EC, but it also exposes certain situations where isolation in fact increases demands on EC. Increasing the frictional resistance for sliding EC or locking the wheel/casters in the case of wheel/caster-supported EC is highly recommended for EC in base-isolated buildings to prevent excessive displacement demands. Furthermore, the study suggests several design probability functions that can be used by practicing engineers to estimate the peak seismic demands on sliding and wheel/caster-supported EC in fixed-base and base-isolated buildings.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)


title: Proliferation resistance evaluation of CANDU reactor systems with different fuel cycles

contributor: Engineering Physics and Nuclear Engineering

subject:
proliferation resistance
CANDU
fuel cycle
thorium application

abstract:
In the process of exploring the thorium fuel application in CANDU reactors, it is important to consider the proliferation resistance level as a parameter for comparison with current natural uranium fuel. The concept of a whole fuel cycle was introduced to show the variations in the proliferation resistance level as the material is flowing through the cycle.

The depletion and decay histories were simulated with SCALE 6.1 code and the results such as isotopes composition, decay heat, and radioactivity were used to analyze the material attractiveness of pure heavy metal for weapon production. They also served as the intrinsic features during the proliferation resistance level calculation.

The Multi-Attribute Utility Analysis (MAUA) method developed by Chalton was used to compare different CANDU fuel cycles with quantified values (PR) from the viewpoint of proliferation resistance. To improve the biased MAUA results that gave a PR of 0.76 to CANDU while 0.93 to PWR, the attributes of size/weight and refueling scheme were reconsidered. In addition, the sensitive technology involved was added for the proliferation resistance recalculation.

The results showed an increased PR value of 0.82 for natural uranium CANDU reactor as well as a decreasing trend of PR at the back end. PWR has a PR of 0.82 with revised MAUA method. The PR comparison of thorium and natural uranium fuel indicated that Th/Pu fuel has a slightly higher PR value in the reactor. The Figure of Merit (FOM) method developed by Bathke was used to validate the PR results from another perspective: the attractiveness of pure heavy metals that are suitable for nuclear weapon production.

The results showed that FOM of plutonium keeps increasing with decay time and the trend becomes more significant after disposal in the deep geological repository. The FOM of uranium from Th/Pu cases is higher than that of Pu within several hundred years but maintains a decreasing trend. The decreasing FOM of uranium is preferred for direct disposal in deep geological repository.

The decreased PR level and the increased FOM value of plutonium at the back end of a fuel cycle indicate the importance of implementing the security and safeguard for each facility dealing with nuclear materials. The comparison results of PR and FOM values for different fuel provided feedback and suggestions for the new fuel application.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Strategic Communications Management in Arts Organizations

title: Strategic Communications Management in Canadian Not-for-Profit Arts Organizations: The Tension Between Patron and Product Orientation in Mission-Based Organizations

contributor:
Sevingy, Alexandre
Meath, Michael
Communications Management

subject: Strategic Communications, Arts Marketing, Organization Public Relationships,  Relationship Marketing, Market Orientation, Product Orientation, Strategic   Management, Strategic Orientation, Performing Arts, Not-for-Profit

abstract:
The purpose of this thesis is to determine the extent to which strategic communications

is being practiced, and its implications on organizational performance in the Canadian

arts sector.  This thesis discusses the unique characteristics of not-for-profit charitable

performing arts organizations within the context of strategic communications.  As a

mission-based field, the not-for-profit arts sector operates under the premise that it

must find a market for its product, instead of finding a product for its market.  Building

on communication and arts marketing theories, this thesis posits that strategic

communications management can contribute to the success of arts organizations and

address the gap between arts products and its market.  In particular, this thesis analyzes

the following components of strategic communications management, in relation to the

practices of the Canadian arts sector: relationship management/marketing,

interpersonal relationship values, organization public relationship values, and market

orientation.

abstract: Thesis

abstract: Master of Communications Management (MCM)

abstract:
The purpose of this thesis is to determine the extent to which strategic communications

is being practiced, and its implications for organizational performance in the Canadian

arts sector.  This thesis discusses the unique characteristics of not-for-profit charitable

performing arts organizations within the context of strategic communications.  Building

on communication and arts marketing theories, this thesis posits that strategic

communications management can contribute to the success of arts organizations and

address the gap between arts products and patrons.


title: EXERCISE ENHANCES ALLOCENTRIC PROCESSING AND HIPPOCAMPAL FUNCTION IN THE ADULT BRAIN

contributor:
Becker, Suzanna
Neuroscience

subject:
Exercise
Spatial memory
Neurogenesis
Chronic stress
Depression
Hippocampal function

abstract:
This experiment explored whether a long-term aerobic exercise program may induce significant structural and functional changes in the hippocampus, an area of the brain that is important for spatial navigation and memory formation. Based on existing rodent studies, we hypothesize that exercise will cause a shift to allocentric processing, away from a less robust egocentric learning strategy. It is possible that exercise-induced relief of chronic stress, which contributes to improved hippocampal function, will increase reliance on allocentric spatial navigation. Neurogenesis, which occurs in the dentate gyrus region of the hippocampus, is another indicator of hippocampal function that may influence this shift to allocentric learning.

The current study examines whether six weeks of aerobic exercise enhances allocentric processing in healthy young adults. Forty-nine young adults (35 female; age range 18-29 years) were randomly assigned to one of three groups: 1) High intensity interval training group, 2) Moderate intensity training group, or 3) Non-exercising control group. Hippocampus-dependent memory was assessed before and after the intervention on a Virtual Reality Water Maze task, and a high interference memory task, the Mnemonic Similarity Task (MST) which may be dependent on hippocampal neurogenesis. Levels of chronic stress and depression were measured using the Beck Depression Inventory II. It was expected that exercise would improve spatial memory performance on the water maze task, and that performance would improve in proportion to enhanced fitness levels. This improvement in spatial memory performance was expected to correlate with the two indicators of hippocampal function that were assessed in the current study—chronic stress and performance on the high interference memory task.

Six weeks of regular aerobic exercise resulted in a 21.5% improvement in spatial memory performance on the water maze task, indicating improved hippocampus-mediated spatial memory function. Improvements displayed by high intensity exercisers were greater than those observed in the moderate intensity exercisers, suggesting that higher intensity exercise may be more effective in enhancing hippocampal function. Importantly, low responders to exercise exhibited a 30% improvement in water maze performance, suggesting that even minor fitness improvements can lead to significant cognitive gains. Chronic stress and depression, and performance on the MST were not significantly associated with changes in spatial memory performance; however trends observed may offer some explanation to the aforementioned changes in spatial memory. Findings from the current study have important implications for treatment options in populations that are currently, or at risk of suffering from impaired hippocampal function.

abstract: Thesis

abstract: Master of Science (MSc)


title: LOSS OF COOLANT ACCIDENT SIMULATION FOR THE CANADIAN SUPERCRITICAL WATER-COOLED REACTOR USING RELAP5/MOD4

subject: Safety analysis, Canadian SCWR, LOCA

abstract:
Canada has participated in the Generation IV International Forum (GIF) collaboration in the area of Super Critical Water-cooled Reactors (SCWR). Similar to the current CANDU technologies, in the Canadian SCWR design the low pressure heavy water moderator system is separated from the supercritical coolant system (25MPa). The High Efficiency Re-entrant Channel (HERC) design in the Canadian SCWR has multiple coolant regions (i.e. coolant in the downward center flow tube and coolant in the upward outer fuel region) and provides thermal isolation between the moderator and heat transport system fluid. Although the overall reactivity feedback in the channel is negative for equilibrium density decrease transients, a temporary positive reactivity may be induced during non-equilibrium conditions such as cold-leg Loss of Coolant Accidents (LOCA). The primary objective of this study is to investigate the fuel and coolant behaviors under postulated LOCA transients, in particular those caused by cold-leg breaks, and to demonstrate the effectiveness of several proposed safety systems in the Canadian SCWR.
The one-dimensional thermalhydraulic system code RELAP5 has been used for the safety analysis in many LWRs. The latest version RELAP5/MOD4 has been improved to accommodate supercritical water and is used in this study. A RELAP5 model is constructed based on the most recent Canadian SCWR design. The 336 fuel channels are split into two representative groups each with a series of hydraulic and heat structure models. A benchmark study is conducted by comparing RELAP5 to CATHENA simulations and shows good agreement for both steady-state and transient predictions.
The RELAP5 model is then used to predict the system response to several postulated LOCA transients. For a 100% (single-ended) cold-leg break located in between the feedwater pump and the inlet plenum, the system pressure immediately drops followed closely by a flow reversal with rapid discharge from the break. A brief power pulse (178%FP) is observed under this non-equilibrium depressurization scenario. The transient simulations show the potential for two sheath temperature maxima, one early in the transient as a result of the power pulse and the subsequent flow-power mismatch, and another later peak resulting from the fuel heat-up under near stagnant channel flow conditions (such as in the failure of the Emergency Core Cooling Systems) as the heat transfer regime changes to radiation dominated. The Automatic Depressurization System (ADS) located on the hot-leg side mitigates the later fuel heat-up by introducing forward channel flows. This effect is enhanced by additional coolant supplied from Low Pressure Coolant Injection (LPCI) which is part of the Emergency Core Cooling System (ECCS). Under the 100% break LOCA/LOECC transient, the core inventory is depleted rapidly after the break and thermal radiation becomes the dominant heat removal mechanism. The highest MCST, 1331 K, is achieved approximately 136s after the break and meets the safety criterion (1533 K). Beyond this time the sheath temperatures gradually decrease either by the continuous LPCI from the reactor sumps, gravity driven core cooling, or in the event of a failure of those systems by the Passive Moderator Cooling System (PMCS).
LOCAs initiated by break sizes varying from 5% to 100% of the cold-leg cross-section area are simulated under loss of ECCS. In this specific design, break sizes less than 15% are defined as SBLOCAs and show an early pressure increase up to the Safety Relief Valve (SRV) setpoint. During SBLOCAs, the first MCST peak is more limiting than the large LOCA case because of insufficient fuel cooling caused by relatively low reverse flow. However, these lower reverse flows prolong the period of blowdown cooling and hence help to mitigate the secondary MCST peak. The worst LOCA case occurs in the 15% break case with a maximum cladding temperature of 1450 K. The results showed the most sensitive parameters are delays associated with SDS action, emissivity and ADS actuation parameters.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Bandlimited Optical Intensity Modulation Under Average and Peak Power Constraints

contributor:
Hranilovic, Steve
Electrical and Computer Engineering

subject: signal space

subject: bandlimited intensity channel

subject: optical communications

subject: lattice codes

subject: average and peak power constraints

subject: intensity-modulation direct detection (IM/DD) systems

abstract: Bandlimited optical intensity channels, arising in applications such as indoor infrared communications and visible light communications (VLC), require that all signals satisfy a bandwidth constraint as well as average, peak and non-negative amplitude constraints. However, the signaling designed for conventional radio frequency (RF) electrical channels cannot be applied directly, since they take energy constraints into consideration instead of amplitude constraints. In addition, conventional transmission techniques optimized for broad-band optical channels such as fiber optics, terrestrial/satellite-to-satellite free-space optical (FSO) communications are typically not bandwidth efficient. In this thesis, a two-dimensional signal space for bandlimited optical intensity channels is presented. A novel feature of this model is that the non-negativity and peak amplitude constraints are relaxed. The signal space parameterizes the likelihood of a negative or peak amplitude excursions in the output. Although the intensity channel only supports non-negative amplitudes, the impact of clipping on system performance is shown to be negligible if the likelihood of negative amplitude excursion is small enough. For a given signal space, a tractable approximation approach using a finite series is applied to accurately compute the likelihood of clipping under average and peak optical power constraints. The uncoded asymptotic optical power and spectral efficiencies using two-dimensional lattice constellations are computed. The Monte-Carlo (MC) simulation results show that for a given average or peak optical power, schemes designed in the presented signal space haver higher spectral efficiency than M-ary pulse amplitude modulation (PAM) using previously established techniques.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Rethinking Stratification in Post-Secondary Education: Organizationally Maintained Inequality

contributor:
Davies, Scott
Sociology

subject: Sociology

abstract:
Decades ago, Boudon theorized that highly differentiated education systems would generate higher degrees of inequality than would more homogenous counterparts. In highly differentiated systems, at each point where students were afforded the freedom to select among institutions, Boudon believed that family-based knowledge and capital would produce stratified choices. The presence of differentiation would ensure that students from different SES backgrounds would be distributed in a non-random fashion across education systems. Contemporary theories of stratification within the sociology of education have astutely examined the role played by differentiation. Theories of effectively maintained inequality (EMI) and maximally maintained inequality (MMI) have led the way in this respect. MMI, for example, has theorized the role played by credential levels, depicting privileged students as migrating towards progressively higher credential tiers, and the organizations that service them. The EMI tradition, on the other hand, points to differences in organizational prestige, noting that privileged students migrate to the elite schools within any credential tier. Both theories highlight important dimensions of the hierarchical structure of education and how they can inform our understanding of how individual level stratification occurs through them. That being said, these theories focus only on two basic dimensions of organizational differentiation. They also tend to focus only on differentiation as it occurs within the university sector.
	In this dissertation I bring stratification research into conversation with organizational theory in the hopes of developing a more sophisticated and holistic understanding of differentiation, and thus, social stratification through PSE. I draw on insights from organizational theories to argue that, beyond credential tiers and prestige, PSE organizations are differentiated by the type of relationships (‘stratified connections’) they share with their surrounding environments, organizational networks and organizational sagas. I demonstrate that these often ignored mechanisms actively magnify organizational inequalities that exist within and across sectors of PSE.
	I adopt a mixed methodological approach for this dissertation. To examine organizational relationships with external environments, I draw upon sources documenting the characteristics of economic regions, as well as institutional data on program offerings and organizational structures. To examine organizational networks, I use a qualitative comparison of affiliation data, association documents and interviews. Lastly, to examine disparities in organizational sagas and symbols, I examine promotional materials available on institutional websites as well as other official documents. Such a versatile approach is needed given both the diverse group of questions I explore and the scope of my analysis. Addressing all sectors of Ontario PSE forces me to creatively overcome numerous data deficiencies.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)


title: Design of a System for Target Localization and Tracking in Image-Guided Radiation Therapy

contributor:
Davidson, Timothy N.
Modersitzki, Jan
Moseley, Douglas J.
Terlaky, Tamas
Computational Engineering and Science

subject:
feature detection
motion tracking
digital filtering
fiducial markers
image registration
radiation therapy

abstract:
This thesis contributes to the topic of image-based feature localization and tracking in fluoroscopic (2D x-ray) image sequences. Such tracking is needed to automatically measure organ motion in cancer patients treated with radiation therapy. While the use of 3D cone-beam computed tomography (CBCT) images is a standard clinical practice for verifying the agreement of the patient's position to a plan, it is done before the treatment procedure. Hence, measurement of the motion during the procedure could improve plan design and the accuracy of treatment delivery. Using an existing CBCT imaging system is one way of collecting fluoroscopic sequences for such analysis. Since x-ray images of soft tissues are typically characterized with low contrast and high noise, radio-opaque fiducial markers are often inserted in or around the target. This thesis describes techniques that comprise a complete system for automated detection and tracking of the markers in fluoroscopic image sequences.

One of the cornerstone design ideas in this thesis is the use of the 3D CBCT image of the patient, from which the markers can be extracted more easily, to initialize the tracking in the fluoroscopic image sequences. To do this, a specific marker-based image registration framework was proposed. It includes multiple novel techniques, such as marker segmentation and modelling, the marker enhancement filter, and marker-specific template image generation approaches.

Through extensive experiments on testing data sets, these novel techniques were combined with appropriate state-of-the-art methods to produce a sleek, computationally efficient, fully automated system that achieved reliable marker localization and tracking. The accuracy of the system is sufficient for clinical implementation. The thesis demonstrates an application of the system to the images of prostate cancer patients, and includes examples of statistical analysis of organ motion that can be used to improve treatment planning.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)

abstract:
This thesis presents the development of a software system that analyzes sequences of 2D x-ray images to automatically measure organ motion in patients undergoing radiation therapy for cancer treatment. The knowledge of motion statistics obtained from this system creates opportunities for patient-specific treatment design that may lead to a better outcome.

Automated processing of organ motion is challenging due to the low contrast and high noise levels in the x-ray images. To achieve reliable detection, the proposed system was designed to make use of 3D cone-beam computed tomography images of the patient, where the features (markers) are easier to identify. This required the development of a specific image registration framework for aligning the images, including a number of novel feature modelling and image processing techniques.

The proposed motion tracking approach was implemented as a complete software system that was extensively validated on phantom and patient studies. It achieved a level of accuracy and reliability that is suitable for clinical implementation.


title: MULTISCALE MODELING TECHNIQUES PERTAINING TO COMPOSITIONALLY GRADED MARTENSITIC STEELS

contributor:
Zurob, Hatem
Materials Science and Engineering

subject: Martensite CGM Masing Nanocomposite Structures

abstract: The introduction of composition gradients into the already hierarchical structure of martensitic steel leads to difficulties in modeling that arise from events occurring in the material at different length scales. In this thesis we isolate the features that are important to describing the mechanical properties of martensite and constitutively couple them through their respective length scales. The idea of a representative volume element is rigorously explored in which the microstructure is represented through a Masing model as well as more advanced structures akin to a nanocomposite. As such, we are able to keep track of microscopic yielding and internal stress evolution at the smallest scales (nanoscale through microscale). With the use of representative volume elements, we are able to track events at the largest scale as well by freely being able to change scale. As such, macroscopic phenomenon such as: thermal fields, composition fields, macroscopic loads, and the associated macroscopic phase distributions and stress distributions are evaluated. We conclude by demonstrating the power of this modelling technique in the design and optimization of compositionally graded steel structures via virtual prototyping.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)


title: An Analysis of Soil Respiration in a Temperate Deciduous Forest Ecosystem

contributor:
Arain, M. Altaf
Earth and Environmental Sciences

abstract:
The production and emission of carbon dioxide (CO2) from soils, referred to as soil respiration (Rs), has a significant influence on the global carbon balance. Carbon is acquired by vegetation from the atmosphere through photosynthesis and stored on the surface and in soils as organic matter. This stored organic matter is returned to the atmosphere as CO2 through belowground decomposition of organic matter by microbial communities (heterotrophic respiration) and metabolic activity of roots and mycorrhizae (autotrophic respiration). In this study, we explore temporal and spatial dynamics of Rs in a temperate deciduous forest located in Southern Ontario and how it is influenced by climatic controls over a two year period (2014/2015). The research site is a 90-year-old managed deciduous hardwood forest (Carolinian species) and part of the Turkey Point Flux Station and global Fluxnet network.
An automated soil CO2 efflux system (LI-8100A) was utilized for continuous monitoring of Rs since July 2014 at our site. To better capture the spatial variability of Rs, a portable soil CO2 efflux system (LI-6400) was also used along two 50-m transects. Comparing the two chamber systems, they both measured within one standard deviation of each other indicating that the long-term automatic chamber site is able to account for the spatial variability of the surrounding area. The coefficient of variation among automated chambers ranged from 15 to 85%.
The range of Rs measured during the two study years was 0.72 to 22.74 µmol CO2 m-2s-1. Rs showed a strong soil temperature-driven seasonal trend, though soil moisture accounted for approximately 35% of the variability in Rs. Rainfall events were found to cause pulse response in Rs during and following the precipitation event, causing an 88% increase in Rs. Estimations of total CO2 emissions at the site were modeled using four different techniques, and showed that Rs can account for approximately 84% of total ecosystem respiration. The average annual temperature sensitivity (Q10 value) of the study site was found to be 2.34. The annual Q10 model was improved by the incorporation of temporal variability of Rs (by estimating the Q10 model on a monthly basis) and also through the addition of a logistic soil moisture function. This study will allow us to have a better understanding of the dynamics of Rs and how it responds to its main controlling variables, soil moisture and temperature. It will also help us to determine the impact of climate change and extreme weather events on Rs in temperate deciduous forests and help in developing vegetation ecosystem models.

abstract: Thesis

abstract: Master of Science (MSc)


title: Carbon, water, and energy dynamics of a temperate pine forest during the first decade since plantation on a former cropland

contributor:
Arain, M. Altaf
Geography and Earth Sciences

subject:
carbon
water
energy
net ecosystem productivity
eddy covariance
afforestation
temperate forest
white pine

abstract: This study presents the energy, carbon (C), and water exchange dynamics of a recently afforested temperate white pine (Pinus strobus L.) forest, established on former agricultural land in 2002, in southern Ontario, Canada during the initial thirteen years (2003–2015). Our observations show that the forest became a consistent sink of C after only 5 years of its establishment (ranging from 105 g C m–2 to 216 g C m–2 between 2008 to 2015), owing to sandy soils and low residual soil organic matter from prior agricultural activities. This region frequently experiences low precipitation (P) and soil moisture (VWC) limitations and/or heat stress in late summer, causing a reduction in net ecosystem productivity (NEP). Seasonal and annual dynamics of NEP showed reduced C uptake during years with heat and/or drought events (i.e. 2007 and 2012). In 2007, the impact of a seasonal drought was much more exacerbated when combined with a heatwave, resulting in a strong C source.  Similarly, the inter-annual variability of evapotranspiration (ET) gradually increased with stand age (mean 370 mm yr–1) and water use efficiency (WUE) consistently increased (mean 2.65 g C kg–1 H2O). Quantum yield, α (0.019 to 0.045) and maximum photosynthetic capacity, Amax (4.37 to 33.6 µmol m–2s–1) increased steadily as the size and density of the canopy increased with stand age. Energy fluxes were influenced by canopy development as net radiation (Rn), latent heat (LE), and sensible heat (H) flux increased, while ground heat flux (G) peaked in 2007 and then gradually declined. Our analysis showed that daily C fluxes are primarily driven by Rn and temperature (Ts, Ta) which explained 47%, 61%, 52%, and 68% of the variability in gross ecosystem productivity (GEP), ecosystem respiration (RE), NEP, and ET. This study is a significant contribution to our understanding of the energy, C, and water dynamics of young planted conifer forests and controls on their growth and C uptake. Our findings demonstrate the potential of utilizing white pine as a means to sequester atmospheric CO2 in southern Ontario and other regions of North America with similar climate and site history.

abstract: Thesis

abstract: Master of Science (MSc)


title: Inactivation of IL-15 gene expression does not reduce atherosclerosis in a mouse model of carotid artery narrowing

contributor:
Trigatti, Bernardo
Biochemistry and Biomedical Sciences

subject:
Interleukin 15
Atherosclerosis

abstract:
IL-15 is a pleiotropic cytokine which influences a variety of immune and inflammatory responses. Our lab has previously demonstrated that IL-15 and IL-15Rα promote atherosclerosis. However, the mechanisms by which IL-15 affect atherosclerosis development were not fully defined. In this study, we reported that overexpression of the IL-15 gene resulted in an increase of granzyme B level in the atherosclerotic plaque of ApoE deficient mice. Furthermore, we observed that leukocytes-specific genetic deletion of IL-15Rα reduced the granzyme B level within atherosclerotic lesions from LDLr deficient mice. Collectively, our data shows one of the mechanistic pathways by which IL-15 promotes atherosclerosis development.
Moreover, we tested the role of IL-15 in carotid artery disease. It has been reported previously that immunization of low density lipoprotein receptor deficient mice against IL-15, by inoculating them with bacteria harboring an IL-15 expression plasmid, led to reduced development of diet induced atherosclerosis in carotid arteries whose diameter was restricted to induce a hemodynamic stress. Others, however, reported that injection of wild type mice with an antibody against IL-15 triggered increased neointima formation in carotid arteries that were partially ligated. In our study, we found no differences in the amount of collar/diet induced atherosclerosis in control apoE KO mice and in IL-15/apoE dKO mice.Therefore,inactivation of IL-15 gene expression does not appear to affect the rapid onset of atherosclerosis in carotid arteries of ApoE KO mice induced by a combination of high fat diet and hemodynamic stress.

abstract: Thesis

abstract: Master of Science (MSc)


title: The Value of the Ontario Sport Fishery An Economic Analysis

contributor:
Lonergan, S. C.
Geography

subject: Ontario, sport, fishery, economic, habitats

abstract: Over the past decade public decision makers have become increasingly concerned with the potential impacts of their decisions upon values associated with fish resources. These impacts can often involve large-scale alternation of natural habitats. Recreation is an important use of the fisheries resource. Anglers in Ontario spent more than 43 million days engaged in sport fishing expending more than 650 million dollars within the Province in 1980 (Government of Ontario, 1980). This paper deals largely with conceptual methods of measuring the economic benefits of recreational fishing. It is intended to serve several purposes: to present a review of the economic evaluations of recreational fishing and to expand certain conceptual concepts of the subject. High priority steps that should be taken to develop appropriate fishing values which can be used in policy decisions are also presented.

abstract: Thesis

abstract: Candidate in Philosophy


title: An Integrated Approach to Improve Data Quality

contributor:
Janicki, Ryszard
Computing and Software

subject:
data management
data quality
data mining

abstract: Thesis

abstract: A huge quantity of data is created and saved everyday in databases from different types of data sources, including financial data, web log data, sensor data, and human input. Information technology enables organizations to collect and store large amounts of data in databases. Different organizations worldwide use data to support their activities through various applications. Issues in data quality such as duplicate records, inaccurate data, violations of integrity constraints, and outdated data are common in databases. Thus, data in databases are often unclean. Such issues in data quality might cost billions of dollars annually and might have severe consequences on critical tasks such as analysis, decision making, and planning. Data cleaning processes are required to detect and correct errors in the unclean data. Despite the fact that there are multiple quality issues, current data cleaning techniques generally deal with only one or two aspects of quality. The techniques assume either the availability of master data, or training data, or the involvement of users in data cleaning. For instance, users might manually place confidence scores that represent the correctness of the values of data or they may be consulted about the repairs. In addition, the techniques may depend on high-quality master data or pre-labeled training data to fix errors. However, relying on human effort to correct errors is expensive, and master data or training data are not always available. These factors make it challenging to discover which values have issues, thereby making it difficult to fix the data (e.g., merging several duplicate records into a single representative record). To address these problems in data cleaning, we propose algorithms that integrate multiple data quality issues in the cleaning. In this thesis, we apply this approach in the context of multiple data quality issues where errors in data are introduced from multiple causes. The issues include duplicate records, violations of integrity constraints, inaccurate data, and outdated data. We fix these issues holistically, without a need for human manual interaction, master data, or training data. We propose an algorithm to tackle the problem of data cleaning. We concentrate on issues in data quality including duplicate records, violations of integrity constraints, and inaccurate data. We utilize the embedded density information in data to eliminate duplicates based on data density, where tuples that are close to each other are packed together. Density information enables us to reduce manual user interaction in the deduplication process, and the dependency on master data or training data. To resolve inconsistency in duplicate records, we present a weight model to automatically assign confidence scores that are based on the density of data. We consider the inconsistent data in terms of violations with respect to a set of functional dependencies (FDs). We present a cost model for data repair that is based on the weight model. To resolve inaccurate data in duplicate records, we measure the relatedness of the words of the attributes in the duplicate records based on hierarchical clustering. In the context of integrating the fix of outdated data and inaccurate data in duplicate elimination, we propose an algorithm for data cleaning by introducing techniques based on corroboration, i.e. taking into consideration the trustworthiness of the attribute values. The algorithm integrates data deduplication with data currency and accuracy. We utilize the density information embedded inside the tuples in order to guide the cleaning process to fix multiple data quality issues. By using density information in corroboration, we reduce relying on manual user interaction, and the dependency on master data or training data.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Axenic Culture of House-Fly Larvae and the Influence of Stored Nutrients on Adult Dietary Requirements for Survival and Reproduction

contributor:
Davies, D. M.
Biology

subject: axenic, culture, larvae, nutrients, dietary, reproduction, survival

abstract: Larvae of the house fly, Musca domestica L. , were reared axenically on semi-synthetic media and their performance both as larvae and as adults was assessed in comparison to that of flies reared on an undefined wheat-bran medium. Three components of a standard sterile casein-base medium, i.e., sodium oleate, RNA and cholesterol, were assessed as to their effects on both the larval and adult stages. All improved larval growth, with cholesterol being essential. It has been substantiated that specific larval nutrient reserves were transferred to the adult. Larval nutrition influenced fecundity through its effect on adult survival and vigour, number of eggs developed, and the adult hormonal system.

abstract: Thesis

abstract: Master of Science (MSc)


title: Verification and Implementation of Embedded Systems from High-Level Models

contributor:
Sekerinski, Emil
Computing and Software

abstract:
Existing modelling tools for embedded systems analyze models that do not necessarily reflect executable code. We propose a holistic approach that includes visual modelling of the system and its environment, qualitative and quantitative verification of the model, and automated executable code generation.
For high-level modelling, we introduce pCharts, a variant of hierarchical state machines with state invariants, probabilistic transitions, timed transitions, stochastic transitions, state costs, and transition costs. With embedded systems in mind, pCharts follow an event-centric interpretation, in which events are executable procedures, implying that their execution is fast enough that no queuing of events is needed.
Our pCharts tool, pState, allows the whole system to be formally analyzed and code for executable parts generated. The goal is an automated approach from modelling and analysis to code generation. On a series of case studies, we demonstrate this technique.
An off-the-shelf probabilistic model checker is used for analysis by compiling and transforming a hierarchical pCharts into a flat collection of probabilistic guarded commands with costs. From the pCharts model, also executable code that preserves the verified properties can be generated.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)


title: Enhancing a Home Care eHealth Application for Stroke Survivors with Multiple Chronic Conditions – Bringing Primary Care into the Circle of Care

contributor:
Valaitis, Ruta
eHealth

abstract:
The Canadian elderly population living with multiple chronic conditions (MCCs) is increasing. Multiple health care settings need to be involved in patients’ care management with this vulnerable group. Therefore, meaningful collaboration and communication among health care providers in different sectors, especially at transition points, is highly desirable. This study focuses on the co-design of an expansion of an existing eHealth App (MyST) to include primary care providers who are in the stroke survivors’ circle of care. MyST was originally developed for the home care sector and is currently accessible by home care providers, patients and their caregivers.
Primary care providers, another group of users of the proposed enhanced version of MyST, were not engaged in the design process. The objective of this study is to identify this user group’s requirements and develop specifications for the design and development of MyST 2 to be implemented in real practice settings.
Persona-scenario co-design methodology was used for data collection. Two persona scenario discussion sessions were conducted with 5 health care professionals from different primary care practices. Three nurses participated in one session, and a dietitian and a social worker participated in another session. Participants in groups created personas and scenarios where their persona interacted with members of the circle of care using MyST 2.
Eight themes were identified in the data analysis process: Inter-professional team communication, Patient safety approach, Access to non-medical information, Facilitation of referral to community services and resources, Patient-centred care, System integration, Clinic EMR as a complementary tool, and Implementation considerations. Related to each theme, a list of design specifications was created, including required modules and features, and implementation specifications such as hardware requirements, team members’ responsibilities, MyST 2 use policies, patient privacy, and provider training. The identified requirements will also inform the design and development of future Apps that support patients with MCCs who require home care.

abstract: Thesis

abstract: Master of Science (MSc)


title: THREE ESSAYS ON THE ASSOCIATION OF ECONOMIC CONDITIONS WITH THE HEALTH AND HEALTH BEHAVIOURS OF CANADIANS

contributor: Clinical Epidemiology/Clinical Epidemiology & Biostatistics

abstract:
This thesis comprises of three chapters that study the association of economic conditions with the health and health behaviours of adults and the health outcomes of infants.
	The first chapter examines the impact of economic conditions on modifiable health behaviours, weight-related health (proxied by BMI), self-assessed mental health, life stress and general health of Canadians using data from the first cycle of the Canadian Community Health Survey (CCHS) to the year 2013. More specifically, using variation in unemployment rates at the Census Metropolitan Area (CMA) level, we estimate two-way fixed effect models to investigate how local labour market changes affect these health outcomes. Results suggest that most estimates are small and not statistically significant but that important exceptions exist which imply that recessions pose threats to the health status of the population and need to be appropriately considered by health planners and practitioners alike.
	In the second chapter we use the Canadian Vital Statistics Birth and Death database over the 1976 to 2011 period to investigate how economic conditions are associated with infant mortality, neonatal mortality (death within the first 28 days of life), postneonatal mortality (death from 28 days onward to less than 365 days), the crude birth rate, birth weight, the percentage of babies born weighing less than 2500 gram, and the percentage of babies born weighing less than 1500 grams. A model with province and year fixed effects, clustered at the provincial level, is estimated. This model differences out time invariant unobserved heterogeneity over the period studied and provides unbiased coefficient estimates. For example, some geographic areas may experience both poor health and high unemployment but a causal relationship does not exist. If individuals within provinces have similar unobservable characteristics errors may be correlated - clustering addresses this to provide robust standard errors. The results of this study suggest that worse economic times negatively impact the health of infants.
	The third chapter re-examines the relationship between infant health outcomes and economic conditions studied in chapter 2 undertaking a sensitivity analysis related to the choice of economic proxy, model specification and the time frame of analysis. This study confirms that worse economic times are not good for infant health, however, we find that using the employment rate there is a robust relationship between good economic times and infant health.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)


title: A Study of Recombination Mechanisms in Gallium Arsenide using Temperature-Dependent Time-Resolved Photoluminescence

contributor:
Kleiman, Rafael N
Engineering Physics

subject:
semiconductors
photovoltaics
solar energy
radiative efficiency
time resolved photoluminescence
photoluminescence decay
gallium arsenide
GaAs
III-V
direct bandgap
lifetime
diffusion
surface recombination
trapping
deep levels
EL2
dominant defect
defect characterization
photoluminescence spectroscopy
analytical methods
defect identification
double heterostructure

abstract: Recombination mechanisms in gallium arsenide have been studied using temperature-dependent time-resolved photoluminescence-decay.  New analytical methods are presented to improve the accuracy in bulk lifetime measurement, and these have been used to resolve the temperature-dependent lifetime.  Fits to temperature-dependent lifetime yield measurement of the radiative-efficiency, revealing that samples grown by the Czochralski and molecular-beam-epitaxy methods are limited by radiative-recombination at 77K, with defect-mediated nonradiative-recombination becoming competitive at 300K and above.  In samples grown with both doping types using molecular-beam-epitaxy, a common exponential increase in capture cross-section characterized by a high value of E_infinity=(258 +/- 1)meV was observed from the high-level injection lifetime over a wide temperature range (300-700K).  This common signature was also observed from 500-600K in the hole-lifetime observed in n-type Czochralski GaAs where E_infinity=(261 +/- 7)meV was measured, which indicates that this signature parametrizes the exponential increase in hole-capture cross-section.  The high E_infinity value rules out all candidate defects except for EL2, by comparison with hole-capture cross-section data previously measured by others using deep-level transient spectroscopy.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Reactive Extrusion of Phosphate Cross-linked Resistant Pea Starches

contributor:
Thompson, Michael
Chemical Engineering

subject:
reactive extrusion
resistant starch
pea starch
phosphorylation
cross-linking
extruded pea starch phosphates
pulse starch

abstract:
The primary objectives of this study were to develop an effective reactive extrusion process to produce granular phosphorylated pea starches with enhanced enzyme resistance, and examine the effects of bulk phosphorylation conditions on the morphology, physicochemical and functional properties of extruded pea starch phosphates. Two types of commercially available pea starches (NutriPea and Meelunie) were chosen as the research subjects in this study with differing native resistance. A number of methods including optical microscopy, SEM, ICP-OES, Englyst method, DSC and rapid visco analysis (RVA) were used to characterize the morphology and properties of extruded pea starches.
The effects of feed formulations and extrusion conditions on phosphorus incorporation and Englyst digestion profiles were examined systemically. The results showed that phosphorus content and digestion profiles were highly dependent on the feed moisture. Enzyme resistance did not positively correlate with phosphorus content for extruded pea starch phosphates in contrast to their counterparts prepared by conventional aqueous slurry. This was because extrusion processing can markedly increase the susceptibility of pea starch granules to enzymatic digestion. Lower feed moisture content (40%) gave lower phosphorus content, significantly lower RDS content, and higher SDS and/or RS content. Bulk phosphorylation in the extruder resulted in decreased RS2 content but increased RS4 content. Screw geometry with excessive mixing index was not desirable in terms of producing resistant starch. High screw speeds (150rpm and 200rpm) and low feed rate (1.02kg/h) brought about higher yields of SDS and RS in spite of lower phosphorus incorporation.
Reactive extrusion of pea starches under optimized conditions achieved a significant but moderate increase either in RS content (from 18.67% to 22.57% for NutriPea) or in SDS content (from 37.18% to 42.23% for Meelunie) compared to their native counterparts. However, RS and SDS content could not be improved simultaneously at least based on these pea starches and the reactive extrusion processes in this study. The optical and SEM micrographs confirmed that the granule integrity was largely retained after optimized reactive extrusion process. DSC thermograms found no significant correlation between gelatinization characteristics and Englyst digestion profiles. Evidenced by RVA pasting profiles, NutriPea pea starch phosphates exhibited enhanced thermal and shear stability in comparison to their native counterpart.
A novel foaming injection technology of cross-linking reagents solution was pioneeringly introduced to uniformly coat all starch particles at the lowest moisture level possible during the continuous production of granular NutriPea pea starch phosphates. Yet, the resulting phosphorus incorporation was much lower than expected and would require further studies.

abstract: Thesis

abstract: Master of Applied Science (MASc)

abstract: The Canadian food industry is increasingly interested in the potential to probe new avenues to produce enzyme-resistant food starches from pulses starches. Although extrusion cooking is commonly used for manufacturing cereals, snacks and other food products, no research has been reported on using an extruder to rapidly produce resistant pulse starches for functional food ingredients. This study aimed to develop an effective reactive extrusion process to produce phosphate cross-linked pea starches with enhanced enzyme resistance (i.e., increased slowly digestible starch (SDS) and resistant starch (RS) content ) based on an examination of the effects of reaction conditions on the properties of extrusion products. Two types of commercially available pea starches, NutriPea and Meelunie, were chosen as subjects of the research. The cross-linked pea starches under optimized conditions achieved a significant but moderate increase either in RS content (for NutriPea) or in SDS content (for Meelunie) compared to their native counterparts. However, RS and SDS content could not be improved simultaneously at least based on these pea starches and the reactive extrusion processes in this study.


title: Kinematic Simulation for Turbulent Particle-Laden Flows

contributor:
Lightstone, Marilyn
Tullis, Stephen
Mechanical Engineering

subject:
Particle-laden flows
Turbulence modelling
Two-phase flows
Kinematic simulation
Turbulence

abstract: Kinematic simulation (KS) is a means of generating a turbulent-like velocity field, in a manner that enforces an input Eulerian energy spectrum. Such models have also been applied in particle-laden flows, due to their ability to enforce spatial organization of the fluid velocity field when simulating the trajectories of individual particles. A critical evaluation of KS is presented; in particular, its ability to reproduce single-particle Lagrangian statistics is examined. Also the ability of KS to reproduce the preferential concentration of inertial particles is explored. Some numerical results are presented, in which fluid tracers and inertial particles are transported alternatively by (1) simulated turbulence generated by direct numerical simulation (DNS) of the incompressible Navier-Stokes equations, and (2) KS. The effect of unsteadiness formulation in particular is examined. It is found that even steady KS qualitatively reproduces the continuity effect, clustering of inertial particles, elevated dispersion of inertial particles and the intermittent turbulence velocity signal. A novel method is then motivated and formulated, in which, for input RANS parameters, a simulated spectrum is used to generate a KS field which enforces a target Lagrangian timescale. This method is then tested against an existing experimental benchmark, and good agreement is obtained.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Turbulence arises in an immense variety of industrial and scientific applications; from weather to automotive design; from medicine to nuclear engineering. Because turbulence is chaotic, it is difficult to make accurate predictions of how a turbulent flow will behave in a given scenario. The objective of my research is to find easier ways of accurately modelling turbulence in a certain class of particle-laden flows.


title: Advanced Materials for Energy Storage in Supercapacitors and Capacitive Water Purification

contributor:
Zhitomirsky, Igor
Materials Science and Engineering

subject:
Polypyrrole
Carbon nanotubes
Activated carbon
Electrophoretic deposition
Symmetric supercapacitors
Asymmetric supercapacitors
Water purification

abstract:
In this study, polypyrrole (PPy) prepared by chemical and electrochemical polymerization was investigated as the electrode of electrochemical supercapacitor (ES). New strategies were developed for the fabrication of nano-structured PPy and PPy based nano-composites, which included discovery of advanced anionic dopants and multi-functional nano-crystals, and development of co-dispersing agents. These methods improved the capacitive performance and cycle stability of PPy electrodes.
The results indicated that high material loading and good capacitance retention of PPy was achieved using an electrochemical polymerization method and Ni plaque as the current collectors. Nano-crystalline (CTA)2S2O8 formed by a chemical precipitation method from solutions, containing anionic oxidant (S2O82-) and cationic surfactant (CTA+), could be used as the oxidant to synthesize PPy nano-fibers. We demonstrated that multi-wall carbon nanotubes (MWCNT) can be efficiently dispersed using such nano-crystals. Application of multi-functional nano-crystals is a conceptually new approach for the fabrication PPy coated MWCNT. Moreover, safranin and malachite green were found as universal dispersing and charging agents for cataphoretic deposition of graphene, MWCNT and PPy nano-fibers. It opens new strategies in colloidal and electrochemical processing of PPy nano-composites for ES electrodes.
PPy coated MWCNT, prepared by the multi-functional nano-crystals (CTA)2S2O8, was employed for the fabrication of N-doped activated carbon-coated MWCNT (N-AC-MWCNT). The obtained N-AC-MWCNT was uniformly coated and possessed with high surface area. The use of N-AC-MWCNT enabled the fabrication of ES electrodes with high mass loading and high active material to current collector mass ratio. Symmetric and asymmetric ES cells, fabricated by N-AC-MWCNT and aqueous Na2SO4 electrolyte, showed high specific capacitance, good capacitance retention and large voltage window. The positive electrode of asymmetric ES, MnO2 coated MWCNT, was successfully prepared by the chemical reaction between KMnO4 and N-AC-MWCNT. The problem of degradation of MWCNT was avoided by the use of N-AC as the sacrificial carbon.
Significant progress on ES technology has allowed for the development of capacitive dyes removal (CDR) methods using ES devices. In our study, porous carbon materials, N-doped activated carbon coated MWCNT (N-AC-MWCNT) and N-doped activated carbon nano-fibers (N-AC-NF), were developed as the electrodes for CDR applications. The experimental results indicated that capacitive performance of ES cells was influenced by the chemical structure, size, charge-to mass ratio, concentration and redox-active ligands of the dyes. CDR is a promising method for removal of various cationic and anionic dyes, which offers advantages of energy saving and simple electrode regeneration.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Energy Exchange Within a Corn Canopy

contributor:
Davies, J. A.
Geography

subject: energy, exchange, corn, canopy, radiation, heat

abstract:
 The results of an investigation of the micro-climate of a sweet corn canopy is reported at two stages in its development. The purpose of the experiment was to study the height dependence and diurnal variations of the net radiation, sensible and latent heat fluxes, and the turbulent transfer mechanism. Only daytime data were used.

 The depletion of net radiation in the canopy was studied within the framework of the exponential model. A new model for estimating net radiation in the canopy is developed. The pattern of the sources and sinks and the apparent turbulent transfer coefficient for sensible and latent heat in the canopy space are reported.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: The Infrared Spectra Due to H- Ions in the Alkali Halides

contributor:
Timusk, Thomas
Physics

subject: infrared, spectra, ions, alkali, halides, absorption, crystals

abstract: Measurements of the infrared absorption spectra of potassium and sodium halide crystals with substitutional H- ion impurities are presented and compared with calculations which use rigid ion and ordinary shell models for the defect along with phonon data obtained from inelastic neutron scattering measurements. It is shown that the shell model is necessary to give a satisfactory account of the observed anharmonic side band absorption in the sodium halide crystals and that it improves the rigid ion results for the potassium halide crystals. The same model also satisfactorily describes the impurity induced far-infrared absorption in these materials. Some Van Hove singularities observed in the far infrared measurements occur at frequencies predicted from phonon densities of states calculated from neutron scattering data while others occur at slightly different frequencies.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: A Rapid Sediment Analyzer for Sands

contributor:
Middleton, G. V.
Geology

subject: sediment, analyzer, sands, rapid

abstract:
Abstract Not Provided
Thesis
Bachelor of Science (BSc)


title: A Test of the Penman Combination Model for Potential Evapotranspiration

subject: penman, combination, evapotranspiration, irrigated, flux, model

abstract: The Penman combination model for potential evapotranspiration, using the improved wind function of Businger (1956), and measured net radiation, was tested for daily and hourly totals, over an irrigated perennial ryegrass surface at Simcoe, Norfolk County, Southern Ontario. The standard measurement of evapotranspiration was the energy balance method, using the Bowen ratio. The component fluxes of the energy balance were evaluated for ninety-seven hours on ten separate days. A comparison is made of two days with markedly different moisture availability to show how the magnitude of the component fluxes changed. Also the effect of the plant on the evaporative flux is examined. On days when water was non-limiting the model gave excellent results for hourly and daily totals: within 5% of measured evapotranspiration. When water became limiting the model overestimated by as much as 30%. It is further shown that the Penman model appears to be more sensitive to changes in the evaporative flux than the water equivalent of net radiation, The relationship of cumulative dry matter production of the crop and cumulative potential evapotranspiration was examined and was found to be linear for most of the field season, substantiating the hypothesis of Penman (1962).

abstract: Thesis

abstract: Master of Arts (MA)


title: Studies on Deoxyribonucleic Acid Synthesis in Human KB Cells Infected with Human Adenovirus Type 2

contributor:
Mak, S.
Biology

subject: deoxyribonucleic acid, human, cells, adenovirus, cycle, metabolism, population

abstract:
 Human adenovirus, type 2, was utilized to investigate its effects on the host cell population. The progression of KB cells through the various phases of the cell cycle after
infection was studied, with special emphasis of DNA metabolism. At different times after infection, the rate and the amount of viral DNA synthesized was determined and their efficiency of incorporation into virious was investigated.

abstract: Thesis

abstract: Master of Science (MSc)


title: The Oxidation of Fe-Mn Alloys in Carbon Dioxide-Carbon Monoxide Atmospheres at 1000°C

contributor:
Smeltzer, W. W.
Metallurgy and Materials Science

subject: oxidation, alloys, carbon, dioxide, monoxide, atmospheres, iron-manganese

abstract:
 The oxidation kinetics of iron-manganese alloys with manganese contents up to 60 w/o exposed to carbon dioxide-carbon monoxide atmospheres at 1000°C have been determined as a function of gas composition by a gravimetric technique. The experimental conditions were chosen in order that the product of the reaction between metal and oxidizing atmosphere would be a single-phase oxide scale.

 The main objective of this study was to determine the oxidation characteristics of iron-manganese alloys. It has been found that the rate of oxidation of alloys up to 12% manganese at the early stages is limited by interfacial reaction control and later by diffusion processes in the oxide scale. Oxidation rates of alloys containing more than 27% manganese are entirely controlled by diffusion in the oxide scales. The experiments show that the linear oxidation rate is independent of alloy composition. On the other hand, the rate of parabolic oxidation becomes lower with increasing manganese content in the alloy.

 The results from gravimetric measurements and chemical analyses have been interpreted by a model for the diffusion of iron and manganese through the wustite scale. The phenomenological equations from this theoretical approach have enabled calculations of self-diffusion coefficients for iron and manganese and the concentration of defects in the FeO-MnO solid solution as a function of MnO content. The calculated defect concentrations are compared with theoretical models assuming different types of defect structures.

abstract: Thesis

abstract: Master of Engineering (MEngr)


title: ADVANCED MATERIALS AND FABRICATION METHODS FOR FLAME RETARDANT APPLICATIONS

subject:
flame retardants
coatings

abstract: Investigation of flame retardant materials (FRM) identified materials as effective substitutes for halogenated FRM. Many promising materials were tested such as hydrotalcite-type Al–Mg–Zr complex hydroxide, huntite, aluminum hydroxide, hydrotalcite, magnesium carbonate hydroxide pentahydrate, magnesium sulfate heptahydrate, magnesium phosphate hydrate, magnesium chloride hexahydrate, sodium metasilicate pentahydrate, XZO 2022 (Mg3Al) and halloysite. Electrophoretic deposition (EPD) manufacturing technique has been developed for the fabrication of coatings containing the most promising FRM candidates. Identifying charging and dispersion agents, such as poly(4-vinylpyridine-co-butyl methacrylate), humic acid, 2,2′- biquinoline-4,4′-dicarboxylic acid, quaternized hydroxyethylcellulose ethoxylate, 3- phosphonopropionic acid, 16-phosphonohexadecanoic acid, octadecylphosphonic acid, celestine blue, chitosan, to facilitate EPD was of great importance for successful deposition of composite FRM films. The films were investigated using scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, thermogravimetric and differential thermal analysis, as well as Fourier Transform Infrared and Ultraviolet-Visible spectroscopy.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: Technology is expanding, as is our understanding of the environmental and health impacts of chemicals. New flame retardant materials (FRM) must be developed to help protect against fire hazards in increasingly complex products, but care must be taken to avoid implementing dangerous chemicals. This work identifies new FRM which can be efficient replacements for widely used, but toxic FRM. FRM can be applied as a coating cheaply, quickly, and evenly onto substrates of even a complex shape. Techniques and additive chemicals are suggested to create advanced FRM coatings


title: INTERACTING EFFECTS OF POST-WILDFIRE HYDROPHOBICITY AND VEGETATION RECOVERY IN A POOR FEN PEATLAND

contributor:
Waddington, Mike
Earth and Environmental Sciences

subject: Sphagnum Ecohydrology Wildfire

abstract:
To investigate the prevalence and magnitude of hydrophobicity in near-surface peat, a poor fen was characterized into four main post-fire microforms: i) severely burned hollows (SB-H), ii) severely burned Sphagnum fuscum hummocks (SB-Sf), iii) lightly burned S. fuscum hummocks (LB-Sf) and, iv) lightly burned feathermoss lawns (LB-F). The SB-H possessed the most hydrophobicity at the surface (85 ± 20 s) and increased at the 2 cm depth (183 ± 35 s). In comparison, the LB-F experienced an increase in hydrophobicity from the surface (44 ± 10 s) to 5 cm (323 ± 32 s) and remained high to the 10 cm depth (211 ± 31 s). Results on Sphagnum recovery show that only LB-Sf are recovering and the SB-H show marginal recovery of pioneer species such as Ceratodon purpureus and Polytrichum strictum. Moreover, S. fuscum had a mean surface cover of 56 ± 5.9% in the LB-Sf and both pioneer species together possessed a total cover of 15 ± 4.4% in the SB-H. While the vascular cover was correlated with increased transplant productivity which in conjunction with moisture availability (preference for hydrophilic substrate), transplant size (15cm diameter preferred over smaller colonies), and transplant location (SB-H preferred over LB-F) should all lead to decreased mortality in treatments.
However, each species possesses slightly different characteristics that may be more desirable under reclamation conditions. Species that typically form hummock microform types like Sphagnum fuscum, Sphagnum magellanicum, and to some extent Sphagnum angustifolium can retain moisture under dry conditions (Clymo and Hayward, 1982; Andrus, 1986) and may be optimal for areas experiencing droughts or water limitations. Areas that are commonly inundated with water may benefit from a species that grows through lateral expansion such as Sphagnum angustifolium, Sphagnum riparium, or Sphagnum squarrosum (Andrus, 1986). With S. angustifolium possibly being the best generalist due to its ability to remain photosynthetically active throughout a large range of moisture contents, tolerate desiccation, and grow rapidly (Silvola and Aaltonen, 1984; Andrus, 1986).

abstract: Thesis

abstract: Master of Science (MSc)


title: Detecting Non-Elliptical Clusters

contributor:
McNicholas, Paul D.
Browne, Ryan P.
Mathematics and Statistics

abstract: Cluster analysis is used to detect underlying group structure in data. Model-based clustering is a method for performing cluster analysis which involves the fitting of finite mixture models. Regularly these models are fit under the assumption of normality, an assumption that is frequently invalid.  To this end, this thesis focuses on the development of novel non-Gaussian mixture models. Three different mixture models are developed using forms of the multivariate skew-t distribution. Given that it is often computationally infeasible to fit mixture models to high-dimensional data, factor analyzers are employed and, in certain cases, the components of the decomposed component-scale matrices are constrained. This leads to the development of flexible, parsimonious models for analyzing high-dimensional data. A novel non-Gaussian distribution is developed and used for cluster analysis via a mixture model. This model is further extended so that it may be applied to high-dimensional data using factor analyzers. For all models and families of models developed in this thesis, the algorithms used for model-fitting and parameter estimation are presented. Real and simulated data sets are used to assess the clustering ability of all models.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Investigation of frustrated magnetism in double perovskites

contributor:
Gaulin, Bruce
Physics

abstract: This investigation studies the structural and magnetic properties of the double perovskites Ba2YRuO6, Ba2YReO6,Ba2YOsO6, Ba2MgReO6, Ba2ZnReO6, Ba2Y2/3ReO6, Ba2MgOsO6, Ba2ZnOsO6, Ba2CdOsO6, La2LiRuO6, and La2LiOsO6. These compounds were prepared as powders using conventional solid state techniques. Structural characterization was performed with room temperature powder x-ray diffraction, and for most compounds, room temperature and low temperature powder neutron diffraction. The double perovskites in this investigation can be categorized as cubic Fm-3m and monoclinic P21/n. Over the ranges of temperatures measured, no space group changes were detected. Magnetic susceptibilty, magnetic hysteresis, and heat capacity measurements revealed a variation of ground states and magnetism across this selection of double perovskites. Inelastic neutron scattering experiments gave evidence for spin gap formation in almost all of the compounds.

abstract: Thesis

abstract: Master of Science (MSc)


title: Genetics of human obesity in the post-genome wide association study era

subject: GWAS Obesity

abstract:
Obesity has more than doubled worldwide since 1980 and it has become the focus of public health due to a wide range of serious complications. It is believed to be a complex disorder triggered by multiple genes, environmental factors and their interactions. The total number of single nucleotide polymorphisms (SNPs) associated with adult body mass index (BMI) at genome-wide significance level (P<5×10-8) has recently increased to 136. However, these genome-wide association studies (GWAS) have been conducted primarily in populations of European ancestry. This thesis aims to: 1) investigate whether these BMI SNPs are also associated with BMI in other ethnicities (South Asian, East Asian, African, Latino American and Native American) using a multi-ethnic prospective EpiDREAM cohort study; 2) explore the parental and child genetic contributions to obesity-related traits in children from birth to 5 years in the FAMILY cohort; 3) examine the maternal and child genetic contribution of BMI SNPs to maternal gestational weight gain (GWG) and postpartum weight retention in the FAMILY cohort.
	The major findings are: 1) most BMI susceptibility genes identified in Europeans are also associated with BMI in other five ethnicities. The effects of some SNPs and BMI genetic risk score (GRS) were modified by ethnicity; 2) SNPs contributing to adult BMI start to exert their effect at birth and in early childhood. Parent-of-origin effects may occur in a limited subset of obesity predisposing SNPs; and 3) there is no association between maternal and child GRS and GWG. But there is a genetic link between pre-pregnancy BMI variation and offspring birth weight and maternal postpartum weight retention. Taken together, these findings indicate that GWAS of specific ethnic group, children, birth weight and GWG are necessary to look for novel variants and alternative pathways influencing the development of obesity.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Obesity is a chronic disorder triggered by multiple genes, environmental factors and their interactions. Currently most of the common genetic alterations, called single nucleotide polymorphisms (SNPs), associated with adult body mass index (BMI) were identified in populations of European ancestry. This thesis aims to: 1) investigate whether these BMI-associated SNPs are also associated with BMI in other ethnic groups; 2) explore the parental and child genetic contributions in children from birth to 5 years; 3) examine the maternal and child genetic contribution to maternal gestational weight gain (GWG) and postpartum weight retention. The major findings are: 1) BMI SNPs identified in Europeans are partially generalizable to other five ethnicities; 2) The collective SNPs contributing to adult BMI start to exert their effect at birth and in early childhood; and 3) There is a genetic link between pre-pregnancy BMI and offspring birth weight and maternal postpartum weight retention.


title: Hemocyte-pericardial cell interaction during the growth of the dorsal vessel

contributor:
Jacobs, Roger
Biology

subject:
Drosophila melanogaster
Hemocyte
Pericardial cell
Dorsal vessel
Extracellular matrix

abstract:
Drosophila melanogaster has a tubular heart called the dorsal vessel, which is
composed of contractile cardiomyocytes and hemolymph filtering pericardial cells.
During larval development the dorsal vessel (heart) grows in size, and the luminal
space inside the heart expands, however it has not been clear which cells are
responsible for laying the extracellular matrix (ECM) during this expansion.
Hemocytes (white blood cells), pericardial cells and cells of the fat body are candidate
cell types that may secrete ECM for assembly during the growth of the heart lumen.
With gene knock-down techniques we are exploring whether hemocytes participate in
assembly of the heart ECM at this location. Additionally, studies of fluorescently
tagged hemocytes in intact larvae reveal that hemocytes aggregate around pericardial
cells of the dorsal vessel in 3rd instars. Confocal studies of dissected larval hearts
indicate that hemocytes aggregate within infoldings of basement membrane associated
with pericardial cells. Hemocyte-pericardial cell association could indicate that
hemocytes take up proteins that are produced by pericardial cells and deliver them to
other locations or that there might be a previously unidentified hematopoietic site at
the Drosophila larval heart.

abstract: Thesis

abstract: Master of Science (MSc)


title: In vitro selection of fluorogenic RNA-cleaving DNAzymes for colorectal cancer detection

contributor:
Li, Yingfu
Chemistry and Chemical Biology

subject:
DNAzymes
Colorectal Cancer
Sensors
DNA Enzymes
Bacterial Detection

abstract: Colorectal cancer (CRC) is one of the leading causes of cancer death worldwide, accounting for over 600,000 deaths annually. The mortality rate of CRC can be significantly reduced if it is detected early, suggesting the importance of cancer screening in CRC management. Currently, colonoscopy is the gold standard for CRC diagnosis as it is accurate and reliable. However, it is an invasive procedure that is associated with risks of complications, which contributes to the lack of patient compliance in colonoscopy screening. Other noninvasive detection methods suffer from poor sensitivity and specificity. Thus, there remains a great demand for the development of a noninvasive and accurate test for CRC diagnosis. Recently, studies using next-generation sequencing techniques have revealed compositional changes in the intestinal microbiome associated with CRC, implicating the possibility of using fecal microbiome as potential diagnostic markers. Specifically, the level of the gram-negative bacterium, Fusobacterium nucleatum, has been shown to be elevated in CRC patients compared to healthy controls. The work described in this thesis aims to develop unique RNA-cleaving DNAzymes that can distinguish between healthy and CRC stool microbiomes. RNA-cleaving DNAzymes are single stranded DNA molecules that are extensively used as analytical tools for metal ion sensing and bacterial detection. We conducted an in vitro selection experiment and isolated a F. nucleatum-responsive RNA-cleaving DNAzyme sensor, named RFD-FN1, that is activated by a heat stable protein marker by this bacterium. RFD-FN1 is highly specific for F. nucleatum and it has a limit of detection of 107 CFU/mL without culture and a single cell when cultured for 36 hours. The discovery of this novel molecular probe for F. nucleatum presents an important step forward towards the development of a novel DNAzyme-based detection method for colorectal cancer.

abstract: Thesis

abstract: Master of Science (MSc)


title: Enrichment and Characterization of Anaerobic Benzene-Degrading Microbial Cultures

contributor:
Edwards, Elizabeth A.
Civil Engineering

subject: characterization, anaerobic, microbial, cultures, enrichment, benzene, contaminant, bacteria, growth

abstract:
 Biodegradation of benzene, a common groundwater contaminant, occurs readily in the presence of oxygen; however, at contaminated sites, aerobic bacteria often deplete the available oxygen, resulting in anaerobic conditions. Field and laboratory studies have shown that the anaerobic biodegradation of other aromatic hydrocarbons such as toluene occurs readily, while anaerobic benzene biodegradation has only been documented in a handful of studies. Despite these difficulties, benzene biodegradation has been shown to occur under iron-reducing, sulphate-reducing and methanogenic conditions, but not under nitrate-reducing conditions.

 The goal of this thesis research was to enrich and characterize the benzene-degrading microbial populations in microcosms and transfer cultures derived from soil from four different sites. Cultures were amended with potential exogenous electron acceptors (nitrate, sulphate, ferric iron) and the rates of biodegradation under different terminal electron accepting processes were determined. Sustained, anaerobic benzene biodegradation was obtained in transfer cultures containing less than 1% of the original soil inoculum. The rate of benzene degradation was variable, ranging from 1 μM/d to more than 75 μM/d. Growth of bacteria was linked to benzene degradation under sulphate-reducing and nitrate-reducing conditions. Growth was very slow, with doubling times of 9-30 days estimated by modelling benzene depletion curves to the Monod kinetic equation. The rate of benzene degradation was influenced most by biomass concentration and much less by the terminal electron accepting process.

 The ratio of moles of electron acceptor depleted to moles of benzene degraded was calculated and compared to the theoretically predicted ratios to confirm putative terminal electron acceptors. Anaerobic benzene degradation linked to iron reduction, sulphate reduction and methanogenesis was observed in enrichment cultures, corroborating results from previous studies. In addition, in some enrichment cultures, benzene degradation was linked to nitrate reduction. This is the first report demonstrating benzene degradation linked to nitrate reduction.

abstract: Thesis

abstract: Master of Engineering (MEngr)


title: The Structural Effects of Substitution on the 1,3-Dioxolan-2-Ylium System

contributor:
Childs, R. F.
Chemistry

subject: structural, substitution, ions, bond, crystals, oxygen

abstract:
 This thesis deals with 0-substituted carbenium ions. In particular, the relationship between the pattern of substitution and the nature of the charge distribution in the ion are probed by looking at the effects of systematic substituent change on bond distances.

 The model system employed in this investigation is the 1,3-dioxolan-2-ylium ion. A series of five ions were investigated by the preparation of single crystals which were studied using x-ray crystallography.

 The carbon oxygen bond distances around the five-membered dioxolanylium ring were found to be sensitive to changes in methyl substitution at position 4 of the ring. As methyl substitution at this position was increased systematically, an increase in the C4-03 carbon oxygen bond distance was observed.

 Changes in the substituent at position 2 of the dioxolanylium ring also had an effect on carbon oxygen bond distances but of a lesser magnitude than those brought about by methyl substitutions at position 4. The importance of these changes in structure are discussed in terms of the
charge distribution in the cations.

abstract: Thesis

abstract: Master of Science (MSc)


title: The Cyclopropylmethyl Free Radical Clock. Calibration for the Range 30-90°C

subject: cyclopropylmethyl, free, radical, clock, calibration, isomerization

abstract:
 The Arrhenius equation for the ring opening isomerization of cyclopropylmethyl radicals (R•) to 3-buten-1-yl radicals (R•') for the 303-362 K temperature range was determined by thermolysis of cyclopropylmethyl [1-hydroxy-1-methylethyl] diazene in the presence of excess 1,1,3,3-tetra-methylisoindolin-2-yloxyl (Y•).

 Rate constants for coupling of R• with Y• were assumed to be proportional to diffusion controlled rate constants (kd) and rate constants (ki) for the isomerization were calculated from kd (corrected) and product ratios (RY/R'Y). The temperature dependence of ki, given by log(ki/s^-1) = (13.9 ± 0.4) - (7.6 ± 0.1)/θ, is significantly different from that determined by Ingold and co-workers by kinetic epr spectroscopy in the temperature range 128-153 K; log(ki/s^-1) = (11.34 ± 0.85) - (5.94 ± 0.57)/θ, where θ = 2.3 RT kcal mol^-1.

abstract: Thesis

abstract: Master of Science (MSc)


title: Anodic Oxidation of Pentaphenylcyclopentadienes

contributor:
McCullough, J. J.
Chemistry

subject: anodic, oxidation, cyclic, non-polar, cathodic, electrolyte

abstract:
 Cyclic voltammetric oxidation of 1,2,3,4,5-pentaphenylcyclopentadiene has been studied in non-polar chloroalkane solvents (CH2Cl2 and CH2ClCH2Cl). The oxidation is reversible if tetra-n-butylammonium hexafluorophosphate (TBA^+PF6^-) is used as supporting electrolyte, but irreversible when tetra-n-butylammonium perchlorate (TBA^+ClO4^-) or tetra-n-butylammonium trifluoromethane sulfonate (TBA^+OTf^-) are used, and partially reversible when tetra-n-butylammonium tetrafluoroborate (TBA^+BF4^-) is used. Oxidation of 1,2,3,4,5-pentaphenyl-1-methylcyclopentadiene, which has no relatively acidic protons, was reversible with all four supporting electrolytes.

 The criteria for reversibility were observation of cathodic wave on scan reversal, equal anodic and cathodic peak currents, minor dependence of peak potentials on scan rate, v, and linearity of anodic peak current, ipa with the square root of scan rate, v^1/2 , corresponding to Randles-Sevcik equation for reversible processes.

 It is proposed that perchlorate (ClO4^-) and triflate (OTf^-) anions are sufficiently basic to accept a proton from 1,2,3,4,5-pentaphenylcyclopentadiene cation-radical
intermediate, while tetrafluoroborate (BF4^-) and particularly hexafluorophosphate (PF6^-) are less basic, and therefore less reactive.

 Controlled potential electrolysis of 1,2,3,4,5-pentaphenylcyclopentadiene with tetra-n-butylammonium perchlorate as supporting electrolyte affords the cation, which is consistent with an ECE mechanism in which the chemical step is proton loss.

abstract: Thesis

abstract: Master of Science (MSc)