title: A Unified Treatment of Yield Analysis, Worst-Case Design and Yield Optimization

contributor:
Bandler, John W.
Electrical Engineering

subject:
Electrical and Electronics
Electrical and Electronics

abstract:
This thesis addresses itself to what is considered to be one of the most general theoretical problems associated with the art of engineering design. A unified treatment is presented of production yield evaluation, worst-case design and yield optimization. The formulation is suited to nonlinear programming methods of solution.

Viewed in its entirety the approach integrates the following concepts: design centering, assignment of component tolerances, post-production tuning, yield estimation for realistic distributions and modeling of response functions. Many of the ideas can also be used separately depending on the type of design evaluation required, the number of degrees of freedom involved and the availability and properties of suitable simulation programs.

The thesis presents an analytical approach to yield and yield sensitivity evaluation. Basic to the approach is the discretization of the distributions by use of orthotopic cells to which suitable uniform distributions are applied. Multidimensional polynomials provide approximations to actual functions, which may be expensive to compute. Algorithms for updating and evaluating these polynomials are developed to permit efficient use of gradient optimization methods.

Industrially oriented design examples are furnished to justify the theory. A telephone channel (lossy) bandpass filter is considered with relative insertion loss specifications to illustrate the analysis of yield. The cascade connection of nonideal, inhomogeneous sections of rectangular waveguides is considered from the worst-case design point of view. A current switch emitter follower involving transistors, a diode and a transmission line provides a challenging example for yield optimization including parameter correlations.

abstract: Doctor of Philosophy (PhD)


title: Conversations Over Coffee: Reflexivity and Social Work Praxis

contributor:
Greene, Saara
Sammon, Sheila
Social Work

subject:
Reflxivity
Self-awareness
Efficacious
Exigent
Entrenched
Polycentric
Monocentric
Revenant
Extant
Challenges to reflexivity
Factors that enable reflexivity
Social Work
Social Work

abstract: Utilizing autoethnography and thematic analysis, this thesis explores reflexivity and social work praxis. Specifically, it illuminates the phenomenon of reflexivity and its related themes; reflexivity’s multiple meanings, challenges and enabling factors, its link to internal processes, rationale for usage and timeliness of inquiry. The multiple ways that practitioners engage in reflexive inquiry was revealed through dyadic interviews. However, current literature does not reflect this and the breadth and scope of reflexive inquiry is lost within contemporary social work discourse. Therefore, this thesis puts forth multiple definitions of reflexivity, which broaden the scope of reflexive inquiry, contextualize its usage and highlight its indications. The first group of definitions, efficacious, exigent and entrenched reflexivity are defined in terms of four key components; the reflexivity’s focus and center, what the reflexivity seeks and the degree to which reflexivity is utilized as a tool of practice. These definitions shed light on the varying depths of reflexive inquiry. The next group of definitions, extant and revenant reflexivity can serve to highlight to the worker when an experience needs to be reflected upon. The final group of definitions, polycentric and monocentric reflexivity, identify the context in which reflexivity takes place, namely communally or in isolation. The impetus for disseminating these broadened definitions is my belief that their incorporation into contemporary social work discourse and utilization as a required tool of practice will further promote the integration and support of the dual existences of the professional and personal selves; that their procurement into practitioner pedagogy will lead to dedicated space within the practice setting that enables one to be an emotional being, complete with emotional realities while simultaneously coexisting as a social worker, complete with social work related realities. I believe this will result in increased efficiency and productivity to serve and care for our clients, as well as increased worker health and well-being, to serve and care for ourselves.

abstract: Master of Social Work (MSW)


title: The Role of Perceptual Binding in Memory & Awareness

contributor:
Milliken, Bruce
Psychology

subject: perception binding memory attention priming consciousness

abstract: The processes responsible for binding together elements of an experience are known to play a role in guiding behavior across a range of domains within human cognition, including perception, memory, and performance. Broadly speaking, this thesis is concerned with how binding processes might contribute to behavior in another research domain that has received little attention from this perspective, namely, the generation of explicit awareness of statistical relations. More specifically, the primary goal of this thesis was to examine how these binding processes mediate explicit awareness of contingencies between perceptual events, and how this awareness is related to the phenomenological and mnemonic consequences of these binding processes. The empirical work presented in this thesis suggests that awareness of strong statistical regularities is heavily influenced by the relationship between feature bindings across successive visual events, and that mismatches in feature bindings can obscure awareness of these regularities. Furthermore, it was found that binding mismatches likely obscure such awareness by way of their phenomenological and mnemonic consequences. The experimental results from this thesis have important implications for understanding the processes that govern the acquisition of explicit awareness of contingencies, and for theories of visual memory. It is suggested that binding processes may play a role in controlling the coordination between short-term memory representations and ongoing perceptual input.

abstract: Doctor of Philosophy (PhD)


title: Refining Metallurgical Grade Silicon by Chlorination Treatment with Emphasis on Aluminum Removal

contributor:
Petric, Antony
Coley, Kenneth
Irons, Gordon A.
Materials Science and Engineering

subject:
Refining
Metallurgical Grade Silicon
Chlorination
Aluminum
Boron
Solar Grade SiliconRemoval
Metallurgy
Other Materials Science and Engineering
Metallurgy

abstract:
A supply shortage of solar-grade silicon in recent years resulted from a rapid expansion of the solar cell industry. Therefore, many efforts have been done to obtain reliable metallurgical methods for production of SoG silicon from metallurgical grade silicon.

In this research, refining of metallurgical grade silicon by chlorination treatment with the emphasis on Al removal was investigated. Thermodynamic calculations through Factsage confirmed the feasibility of Al removal in repeated steps of chlorination. Therefore, an Ar+SiCl4 gas mixture with different flow rates was applied to the silicon melt by blowing and injection methods at different temperatures and the ICP-OES was used for analysis of the impurities in silicon.

Results revealed that Al removal from silicon by chlorination treatment under the conditions employed in this study is first order reaction with respect to Al. By increasing the temperature in the chlorination process, the rate constant increases which is related to an increase in the liquid mass transfer rate. Also the observed higher rates of Al removal under injection conditions appear to be the result of improved stirring in the melt rather than an increase in the interfacial area.

abstract: Master of Applied Science (MASc)


title: The Effect of Physical Activity on Bone Mineral Density and Fracture Rate in Very Old Post-menopausal Women

contributor: Clinical Epidemiology/Clinical Epidemiology & Biostatistics

subject:
Osteoporosis
Post-menopause
Physical Activity
Bone Density
Fracture
Clinical Epidemiology
Clinical Epidemiology

abstract: Physical activity is known to benefit many physiological processes, including bone turnover. There are; however, currently no clinical guidelines regarding the most appropriate type, intensity and duration of activity to prevent bone loss. To address this gap in the literature, we performed a retrospective analysis of data from the Canadian Multicentre Osteoporosis Study (CaMos), a prospective cohort of 10,000 adult patients. Female participants aged 75 and over provided information regarding their daily activity levels, including the amount of time spent each week performing moderate physical activity (e.g. housework, brisk walking). Outcome measures included bone mineral density and fracture rate. Multiple and linear regression analysis was used to determine the effect of increasing amounts of moderate physical activity on the outcome measures. The results indicate that a step increase in the amount of physical activity performed each day resulted in a positive effect on bone mineral density at the hip, Ward's triangle, trochanter and femoral neck (B=0.006 to 0.008, p

abstract: Master of Science (MSc)


title: MICROFLUIDIC DEVICES FOR NEMATODE-BASED BEHAVIOURAL ASSAYS USING ELECTROTAXIS

contributor:
Selvaganapathy, Ponnambalam Ravi
Gupta, Bhagwati P
Ching, Chan Y
Mechanical Engineering

subject: Nematode

subject: C. elegans

subject: Electrotaxis

subject: Microfluidic

subject: Movement Assay

subject: Drug Screening

subject: Immobilization

subject: Sorting

subject: Detection

subject: Localization

subject: Animal Sciences

subject: Behavioral Neurobiology

subject: Bioelectrical and neuroengineering

subject: Biological Engineering

subject: Biomechanical Engineering

subject: Biomechanics and biotransport

subject: Biomedical devices and instrumentation

subject: Biotechnology

subject: Electro-Mechanical Systems

subject: Other Biomedical Engineering and Bioengineering

subject: Pharmacology, Toxicology and Environmental Health

subject: Animal Sciences

abstract: Small nematode model organisms such as Caenorhabditis elegans are widely used in the fields of neurobiology, toxicology, drug discovery, etc. They are advantageous due to their fully characterized genomic and cellular system. Traditional screening methods involve the exposure of animals to chemicals/drugs inside multiwell-plates while its effects on growth, movement and other cellular/sub-cellular processes are monitored by visual inspection. Yet, these methods are time-consuming, low-throughput, expensive, tedious, difficult to control, hard to modulate instantaneously, prone to subjectivity and not suitable for movement-based behavioural assays. Hence, a method to induce and to quantify movement on-demand in a rapid, sensitive, precise and reversible manner would greatly facilitate biological studies. In this thesis, microfluidic engineering approaches have been utilized in nematode-based assays due to their potential to obtain high precision measurements in a low-cost, rapid and automated manner. Movement response of worms to a diverse range of electric signals has been quantitatively characterized. DC and pulse-DC electric fields have been shown to stimulate worms’ swimming towards the negative electrode inside a microchannel (electrotaxis). AC electric fields were used to inhibit movement on-demand. Animals’ movement has been characterized in terms of speed and range of motion, body-bend frequency and turning time. Electrotaxis was shown to be mediated by neuronal activities and correlations between animal’s behaviour and neuronal signalling has also been demonstrated. Using this basic understanding, multiple microfluidic components such as position sensors and electric immobilizers have been developed. Electrotaxis has then been applied as a technique to sort worms in accordance to their size/age and phenotype as well as to perform drug screening at a single-animal level. Integration of the techniques and components developed during this research is expected to have a significant impact on the development of an integrated microfluidic platform for high throughput automated behavioural screening of nematodes with applications in drug discovery, toxicology, neurobiology and genetics.

abstract: Doctor of Philosophy (PhD)


title: Magnetic Properties of Electrodeposited Nanocrystalline Ni-Fe alloys

contributor:
Niewczas, Marek
Materials Science and Engineering

subject:
Coercivity
saturation magnetization
SQUID
exchange length
Other Materials Science and Engineering
Other Materials Science and Engineering

abstract:
Ni-Fe alloys have been used in industrial applications over the past century due to their unique mechanical and magnetic properties. Currently, researchers are interested in enhancing the performance of Ni-Fe alloys by modifying their microstructure. An example of this would be the use of ultra-fine nanocrystalline Ni-Fe alloys for magnetic shielding products that are uniquely shaped and cost effective. These nanocrystalline materials usually exhibit good soft magnetic properties, such as high saturation magnetization, low coercivity and good magnetic permeability. The following study has been devoted to the magnetic properties of electrodeposited nanocrystalline Ni-Fe alloys.

The structure and texture of electrodeposited Ni-Fe alloys was studied by two-dimensional XRD. The Ni-Fe alloys with Fe content from 24.9at. % to 54.2at. % were comprised exclusively of the FCC phase. For 60.2at. % Fe sample, a mixed phase of BCC and FCC structure was found. The lattice parameter increased with increasing Fe content until 54.2at. %, and then decreased due to the presence of BCC structure. The increase in lattice parameter was attributed to the iron replacement of nickel in the Ni crystalline lattice. Texture analysis shows that all Ni-Fe alloys with different Fe content exhibit the fiber texture with a major component of theaxis aligned perpendicular to the sample plane. A second component iswith a significantly lower volume fraction. It also shows that the Ni-Fe alloy with 44.2at. % Fe exhibits the highest volume fraction of random orientation.

Magnetic measurements showed that all Ni-Fe nanocrystalline alloys exhibit soft magnetic properties with narrow hysteresis loops. The saturation magnetization increased linearly with increasing Fe content. The magnetization at T = 2K were slightly higher than that at T = 298K. The lowest coercivity~6Oe was obtained at 44.2 at. % Fe content.

Good agreement between Random Anisotropy Model (RAM) theory and experimental data for all the Ni-Fe alloys has been obtained. By fitting the high field magnetization curve with the Law of Approach to Saturation (LATS), the magnetocrystalline anisotropy constant (Keff) were obtained. Keff decreased with increasing temperature. Also, the ferromagnetic exchange lengths for each Ni-Fe alloy were calculated. They are 26nm, 21nm, 19nm, 18nm, 17nm for Ni-24.9at.%Fe, Ni-33.1at.%Fe, Ni-44.2at.%Fe, Ni-54.2at.%Fe, Ni-60.2at.%Fe at room temperature, respectively. The exchange lengths are larger than the average grain size (D) for all of the samples. The results confirmed the feasibility of Random Anisotropy Model for the prediction of the magnetic properties of the nanocrystalline Ni-Fe alloys fabricated by electrodeposition.

abstract: Master of Applied Science (MASc)


contributor:
Service, Elisabet
Kuperman, Victor
Anderson, Catherine
Cognitive Science of Language

subject:
reading deficits
adolescents
morphology
remedial reading intervention
complex words
lexical decision
Reading and Language
Reading and Language

abstract:
Complex Word Processing in Teenage Poor Readers- Does Morphological Knowledge Help or Hinder?

Abstract

This longitudinal study addressed development of morphological awareness in fourteen-to-seventeen-year-olds reading disabled (RD) high school students enrolled in the Wilson Reading Program (Wilson, 1989). Our lexical decision experiment and reading fluency assessment took place in the first (session 1) and last months (session 2) of the school year that included training with morphologically complex English words. The lexical decision stimuli were composed of derived (critical), compound (bathtub) and pseudo-complex (postpone) words from the training program (trained words), matched complex words not in the training program (untrained words), and nonwords. Accuracy and response times were compared between sessions, and with a comparison group of age-matched typical readers. The RD group did not demonstrate large post-training gains in reading fluency, but, there were significant improvements in accuracy and speed in visual lexical decision. These improvements did not extend to auditory lexical decision, suggesting that the observed improvements in visual word recognition were a result of the training, and not a practice effect due to multiple testing sessions. Additionally, there was post-training improvement in both trained and untrained words implying that the RD students were able to generalize their acquired knowledge of grapheme-phoneme mappings and morphological processing to novel words. Both the RD and comparison group demonstrated the same hierarchy of accuracy and response time patterns for complex words suggest a processing advantage for visually presented derived and compound words that is not skill dependent.

abstract: Master of Science (MSc)


title: PHONOLOGICAL PROCESSING OF VISUAL-SPEECH: THE PHONOLOGICAL MAPPING NEGATIVITY (PMN) AMPLITUDE IS SENSITIVE TO FEATURES OF ARTICULATION

contributor:
Connolly, John F
Moro, Anna
Service, Elisabet
Cognitive Science of Language

subject:
speech processing
phonological mapping negativity (PMN)
electroencephalogram (EEG)
phonological processing
speechreading
visual-speech
event related potentials
Cognition and Perception
Phonetics and Phonology
Psycholinguistics and Neurolinguistics
Cognition and Perception

abstract: The goal of this study was to elucidate whether articulations of visual-speech are processed phonologically, and in the same manner as auditory-speech. Phonological processing, measured through the amplitude of the Phonological Mapping Negativity (PMN), was compared across three conditions using the electroencephalogram (EEG). Planned polynomial contrasts compared conditions of related and unrelated linguistic stimuli versus a non-linguistic control stimulus. A significant Site x Condition polynomial trend at posterior sites (Pz and Oz) during the N400 tine window revealed that the unrelated condition was most negative in amplitude, an N400-like deflection in the control condition reached similar negative amplitude, while the related condition was the most positive. A significant quadratic trend of PMN amplitude differentiated between the linguistic conditions and the non-linguistic control at site Fz, but did not differentiate the related and unrelated linguistic conditions from each other. These results support a conclusion that non-lexical speech-like and gurning motions of the lips are treated differently than articulations of a meaningful nature. Moreover, the PMN response patterned similarly in the linguistic conditions, compared to the non-linguistic control, indicating phonological processing. The prediction that PMN amplitude will distinguish visual-speech events congruent or incongruent to a phonologically constrained context was not supported.

abstract: Master of Science (MSc)


title: Studies of the Low Temperature Behaviour of CoNb2O6

contributor:
Luke, Graeme M.
Physics and Astronomy

subject:
Cobalt Niobate
Muon Spin Rotation
Muon Spin Relaxation
Specific Heat
Crystal Growth
Optical Floating Zone
Condensed Matter Physics
Materials Chemistry
Condensed Matter Physics

abstract:
This thesis is the result of several experiments designed to probe the low temperature physics underlying the 1D-Ising-like behaviour of chains of spins in the structure of Cobalt Niobate, CoNb2O6. A collection of prior work has been done by several groups prior to this, focusing on mapping the phase diagram above 0.5K. Interest in this material was renewed recently based upon theoretical work and experimental confirmation of the unique structure of the spins in the system. The bulk of this work was done at temperatures below the previously investigated range to probe the unique properties of this system.

The material was grown at McMaster University using the optical floating zone technique from oxide powders. The crystal was examined and oriented using single crystal and Laue diffraction and was cut for use in further experiments. Squid magnetometry was used to confirm the material properties and phase transition temperatures, and was compared to literature values.

Heat capacity measurements were performed locally down to 2K, and by collaborators at Waterloo in the range from 330mK to 1K. The heat capacity measurement confirmed the 2.9K transition and explored the relaxation time of the material. Cobalt niobate was found to have an exceptionally long relaxation time at low temperatures indicating strong spin-spin interactions. A sharp transition with zero applied field was found to become a broad, smooth feature at 2.9K when a small field was applied.

We performed muSR measurements in zero, longitudinal and transverse field. The muSR results confirmed the long relaxation time found by the heat capacity measurements, which may reflect the coupling of the spin system to the lattice. Additionally, the material was never seen to statically order in zero or longitudinal field down to 700mK and up to 1T. The material was found to behave dynamically throughout all the field ranges.

abstract: Master of Science (MSc)


title: Performance comparisons of various runs algorithms

contributor:
Franek, Frantisek
Smyth, William
Anand, Christopher
Computing and Software

subject:
Crochemore
runFinder
crochB
crochB7
Other Computer Sciences
Other Computer Sciences

abstract:
This thesis discusses and describes empirical comparisons of execution times of three programs for computing runs in strings. Since two of the pro- grams were thought to be of O(n log n) algorithms (crochB and crochB7) and the third is an implementation of a linear algorithm (runFinder), it was ex- pected that for larger strings runFinder() will strongly outperform the other two programs in the processing of long strings. The aim of this study is thus manifold. We establish the upper limits of lengths of strings for which the performances of crochB and crochB7 are faster or comparable to the perfor- mance of runFinder; we also investigate what kind of penalty in performance crochB7 incurs for the memory saving implementation; furthermore, we wish to explore the relative trade-offs of using one technique (represented through the programs with which experimentation was gone about) over another: within what context would it be advantageous to utilize one program over another of those that are being investigated.

The motivation for this work is the continuation of work of Franek, Jiang, Smyth, Weng, and Xiao, who implemented a space efficient version of Crochemore’s repetition algorithm [6], and then extended it to compute runs [4, 5]. The three programs tested are:

1. crochB – a direct C++ implementation of the extension of Crochemore’s algorithm for runs by Franek, Jiang, and Weng without any space savings techniques;

2. crochB7 – a space efficient version of crochB by the same authors, 3. runFinder – an efficient C++ implementation by Hideo Bannai from the

iiiDepartment of Informatics at Kyushu University in Japan. His imple- mentation utilizes the linear-time strategy of computing the suffix array of the string; using the suffix array it then computes the LCP array; us- ing the suffix and LCP arrays it computes the Lempel-Ziv factorization; from the Lempel-Ziv factorization all leftmost runs are computed using Main’s algorithm; and the rest of the runs are computed using Kolpakov- Kucherov’s algorithm.

In this thesis, the three programs are discussed, the experimental setup for the performance measurements is described, the measurements are presented and a brief analysis of the results follows. It will be shown that although an expectation of O(n log n) performance can be expected in the case of processing of one category of investigated data by the latest version of the implementation of the Crochemore program, in some circumstances (discussed), a performance expectation of order n2, and in others one between this and one of order n log n will be encountered.

abstract: Master of Science (MSc)


title: Ion Implantation Damage in Semiconductors at Low Temperatures

contributor:
Thompson, D.A.
Electrical Engineering

abstract:
This thesis reports on a systematic investigation of the ion implantation damage in Si, Ge, GaP and GaAs at ≤50K. The damage has been measured "in-situ" using the channeling-backscattering technique. Implantation energies have ranged from 10-250 keV with Z₁ in the interval 2 ≤ Z₁≤ 81.

The study has been divided into two parts, depending on Z₁. For low Z₁ (Z₁ < or ∼ 30), the damage profiles in Si, GaP and GaAs have been extracted at 50K. Discrepancies from the theoretical profiles are evident and can be accounted for in terms of the previously reported Z₁-oscillations in the electronic stopping powers. The radial distribution of displaced atoms is examined in these three materials by systematically introducing small misalignments (ψ ≤ 0.36 ψ₁) between the analyzing beam direction and crystal axis. This "Off-Axis" effect is examined as a function of Z₁, ion dose, and depth. Significant atom relaxations are concluded to extend perpendicular to the channel row by up to ~ 40% of the channel radius. While atom relaxations do not contribute to the measured damage at low ion doses, they can account for up to 50-70% of the measured damage at high ion doses. A quantitative model of the damage-done behaviour has been developed, in which the atom relaxation component is incorporated as being directly proportional to the measured damage.

The number of displaced atoms/ion is found to be greater than the prediction derived from collision theory by up to an order of magnitude for high-Z₁ bombardment. Therefore, the second section of the thesis contains a detailed study of the effect for 7 ≤ Z₁ ≤ 81 in Si and Ge at 35K. The deviation is not an artifact of the channeling-bakscattering technique. It is concluded that an "energy-spike" may be initiated by the high-Z₁ bombardments; the energy-spike induces a local amorphous zone in the semiconductor, thereby accounting for the increased damage. A semi-empirical model of the data is developed, which divides the damage into collisional and energy-spike components. Extensive use is made of molecular ion bombardments, since they provide a simple method of varying the individual ion-induced collision cascade energy density; this allows for a test of the energy-spike concepts. It is concluded that spikes will influence the damage up to energies corresponding to a lower energy density limit of 0.1 eV/atom in Si and 0.01 eV/atom in Ge. The lower energy limit for spike effects is evidently «10 keV. In Si it appears that the amorphization process is best described by a thermal-spike mechanism, whereas in Ge, it is inferred that the athermal collapse of the unstable lattice is more probable. To support the arguments and concepts of the energy-spike, a Monte Carlo computer code has been written to simulate the collision cascade and provide insight into the parameters of the individual ion-induced cascades.

abstract: Doctor of Philosophy (PhD)


title: Dual Task Backward Compatibility Effects are Episodically Mediated

contributor:
Watter, Scott
Milliken, Bruce
Humphreys, Karin
Psychology

subject:
Psychological Refractory Period
dual task processing
backward response compatibility
divided attention
episodic memory
Cognitive Psychology
Cognitive Psychology

abstract: Research on backward response compatibility effects (Task 2-to-Task 1 response priming) in the Psychological Refractory Period (PRP) paradigm has suggested that compatibility effects arise from episodic representations of Stimulus-Response (S-R) pairings (Hommel & Eglau, 2002). However, more recent work suggests that these effects are mediated by S-R rules held online in working memory during dual task performance (Ellenbogen & Meiran, 2008). We sought to dissociate these accounts. In Experiment 1, we observed the development of backward response compatibility effects over time in a common PRP task, following varying degrees of prior single task practice of the PRP component tasks. In Experiment 2, we trained participants on a PRP dual task, and then switched Task 2 to one of three different tasks with variable response mapping overlap with the original Task 2, before finally reverting back to the original PRP tasks. Backward response compatibility effects appeared initially, were abolished during the subsequent interference phase, and then reappeared with the original PRP task. Despite equivalent overall performance across conditions suggesting successful task rule instantiation in working memory to guide task performance, backward response compatibility effects were selectively absent in conditions where current S-R rules were mapped in conflict with prior S-R experiences within the experiment. Both experiments provide evidence in favour of an episodic account of backward response compatibility effects, in which prior learning influences subsequent performance in contextually relevant situations. Implications for the understanding of backward response compatibility mechanisms and parallel processing in the PRP paradigm are discussed.

abstract: Master of Science (MSc)


title: X-ray Spectromicroscopy Study of Protein Adsorption onto a Chemically Patterned Surface

contributor:
Hitchcock, A. P.
Chemistry

subject: Chemistry Chemistry

abstract:
Protein adsorption, the first event in the interaction of tissue with a foreign material, is a complex process. Understanding and controlling protein adsorption is an important issue in biomaterials. Many different techniques have been developed to study protein adsorption from different aspects. In this work, two soft X-ray spectromicroscopy techniques, photoemission electron microscopy (X -PEEM) and scanning transmission x-ray microscopy (STXM) were used to map the interaction of blood proteins on a phase segregated polymer film polystyrene/ polymethyl methacrylate (PSIPMMA) blend. The two techniques provide high chemical sensitivity, through near edge X-ray absorption fine structure (NEXAFS) spectroscopy, and high spatial resolution (~50 nm).

As a surface sensitive technique, X-PEEM was used to study adsorption of albumin onto a PS/PMMA blend under different conditions (concentration, adsorption time, pH, temperature and ionic strength), as well as to compare adsorption of albumin and fibrinogen. STXM, a less surface sensitive technique, was used to study albumin adsorption in the presence of a overlayer protein solution, a study which can not be conducted using X-PEEM.

The results give quantitative spatial distributions of adsorbed protein on chemically different regions of the PSIPMMA blend at the studied conditions. This helps understand protein adsorption in a way different from other techniques. Through technique development and an intensive study of the albumin covered PS/PMMA system, this work has made a contribution to development of biomaterials.

abstract: Doctor of Philosophy (PhD)


title: State Formation and Housing Policies: Assisted Housing Programmes and Cooperative Housing in Postwar Canada

contributor:
Fincher, Ruth
Philosophy

subject: Philosophy Philosophy

abstract:
This thesis examines the causes of change in the assisted housing programmes of the postwar Canadian state, and experience of these changes by cooperative housing producers. It demonstrates that transformations in assisted housing policies and procedures have occurred through class struggle over necessary changes in state intervention in the housing sector. It argues that this process of state development is geographically uneven, and corroborates this claim through studies of experiences of cooperative housing policy implementation in two Toronto neighbourhoods.

The proposed theory of state formation is argued to offer advantages over existing theoretical explanations of housing policy change. These include showing the links between social forces and state development, and providing a clearer specification of how social structure and human agency combine to produce policy outcomes over time and space. The theory argues that changes in the state are the outcome of class struggle and competition over the direction and substance of policy initiatives. It is found that this theory helps to explain the timing and characteristics of postwar assisted housing programmes, and transformations in the regulation of cooperative housing. Analysis of the development of two Toronto cooperatives shows that local relations and practices help to determine how housing policies and implementation procedures are experienced. Thus it indicates how experiences of the state are produced in particular places. It is discovered that recent struggles over assisted housing policies have led to a withdrawal of the state from assisted housing provision, and pressures to deliver community-based housing in more commodified forms. These changes have had contradictory effects on peoples' capacities to deliver housing alternatives to Canadians.

abstract: Doctor of Philosophy (PhD)


title: The effect of cholinesterase inhibitors on the risk of falls and injuries in patients with Alzheimer's disease: A systematic review

subject:
Clinical Epidemiology and Biostatistics
Clinical Epidemiology
Clinical Epidemiology

abstract: Master of Health Sciences (MSc)


title: Rare Earth Elements in the Whitestone Anorthosite

contributor:
McNutt, R.H.
Crocket, J.H.
Geology

subject: Geology Geology Geology

abstract:
An analytical procedure is adopted to determine eight rare earth elements in the Whitestone anorthosite, its constituent minerals, and the surrounding metamorphic rocks. Chondrite-normalized rare earth fractionation trends display the rare earth data.

Distinctive rare earth fractionation trends for anorthosites of different origins are not expected to be found. The anorthosite rare earth fractionation trends reflect the crystal-chemically controlled uptake of rare earths by the mineral phases present, so the rare earth fractionation trends of the plagioclase, clinopyroxene, hornblende and garnet are stressed. The rare earth data are consistent with plagioclase and clinopyroxene being primary phases, and hornblende and garnet beine the products of autometamorphism involving the primary phases ond a residual, Fe-Ti, volatile-rich fluid phase.

The country rock-anorthosite relationship is not elucidated by this rare earth study, except the suggestion that rare earths have been supplied to the metasomatic envelope from the anorthosite or a late stage, residual fluid phase associated with the anorthosite.

The theories of anorthosite origin and their application to the Whitestone anorthosite are discussed in light of rare earth information and previous field and petrologic work. The most probable modes of origin of the Whitestone anorthosite are:

1. early fractional crystallization and accumulation of a plagioclase-rich rock fran a dioritic (possibly contaminated) magma, partial melting and intrusion of the anorthosite into its present geological setting.

2. crystallization of a gabbroic anorthosite magma formed by partial fusion of amphibolite,

3. disruption (with partial melting) of a layered-type anorthosite and subsequent injection of this anorthosite into its present surroundings.

abstract: Master of Science (MS)


title: The Concept of Biblical Sheol within the context of Ancient near Eastern Beliefs

subject: Near Eastern Languages and Civilizations

subject: Comparative Literature

subject: Near Eastern Languages and Societies

subject: Comparative Literature

abstract: *some of the hebrew words may not be written correctly in the abstract. Refer to the e-copy for the correct words.

abstract:
This study sets out to redefine the concept of the biblical netherworld designated שְׁאוֹל, by focusing on the specific contexts within which it is mentioned as well as on the contexts of its semantic equivalents in the Bible. In the course of this study former views are reviewed and modifications suggested on the basis of different interpretations and in the light of new comparative material.

In Chapter I previously proposed etymologies of שְׁאוֹל are surveyed and their linguistic and semantic adequacy critically evaluated. This study proposes a semantic development leading from Hebrew/Aramaic שְׁוֹל- 'to inquire' > 'to call to account' > and probably 'to punish' as relevant.

Chapter 2 examines the contexts in which the semantic equivalents of Sheol appear. It is demonstrated that the contexts of בּוֺר - 'pit', a semantic equivalent of Sheol, always imply the realm of divine punishment, while שָׁ֫חַת - 'pit', another semantic equivalent of Sheol, appears in a similar context in all but one instance. This chapter further indicates the similarities between the biblical vocable חַוֹת - 'the realm of death', which parallels Sheol, and its Ugaritic counterpart Mȏt. These two concepts share a number of physical attributes. The suggestions conveyed by these attributes, however, are basically different. In Ugaritic literature they symbolize the intrinsic aggressiveness of the realm of Mȏt, but in biblical literature they serve to convey divine retributive judgement, thus raising a natural power onto an ethical plane. In the case of yet another semantic equivalent of Sheol, צרע - 'netherworld', there are a number of similarities between the biblical and extrabiblical concepts. Its range of meaning, however, in comparison to biblical Sheol, seems to be both wider and more neutral. While generally having negative denotations, it may appear in neutral and even once in a positive context . Sheol, on the other hand, is attested to in a negative context only, implying divine wrath and judgement.

In Chapter 3 an examination of the contexts in which Sheol proper appears indicates that it is almost exclusively associated with unnatural death. Such a death, implying divine judgement, is further suggested by a literary use of ordeal terminology derived from Babylonian sources. The relationship of this terminology to the biblical אוף - 'catastrophe' has been discussed in an excursus and its Babylonian affinities indicated.

Chapter 4 deals with the descriptive details of Sheol and points out their paucity and vagueness in comparison with extra-biblical accounts of the netherworld. It is shown that most of the physical features of Sheol - cords, snares and fetters - may be explained as conveying the idea of inescapability of divine judgement.

Chapter 5 deals with the ancient Near Eastern notion of 'evil death' as distinguished from natural death, and indicates the relationship between such a death and the denizens of Sheol. The discussion focuses particularly on two groups _ Rephaim and Belial. The former are considered in the light of Ugaritic texts. While in both Ugaritic and biblical texts Rephaim are heroic figures, in the Bible the attitude to them seems to be negative and a polemic vein against a belief in their power may be detected. Part of the explanation for this may be suggested by hints of an ancient myth recounting the unsuccessful rebellion of the Sons of El, among whom the Rephaim may have been numbered. A second group of the dwellers of Sheol are the Belial. This designation is transferred by metonomy from the name of the underworld river to a special category of transgressors - the Belial. These are violators of the basic norms of ethical behavior of Israelite society. These norms are stipulated in the covenant between the Israelite and his fellow man. As a violator of these norms, the Belial merits an 'evil death', and since he cannot be pardoned, he will never rise from Sheol.

The conclusion reached by this study is that the most formative influence on the concept of Sheol on the Bible was the view of God as the divine judge. It was this notion that prescribed the limits of the borrowings from neighboring cultures, entirely precluding a profusion of elements incompatible with the concept of ethical judgement. And it was this notion that accounts for the restriction of descriptive detail of Sheol in the Bible to a bare minimum. The emphasis is on a situation rather than on a locale, the situation of a person under judgement in a place of judgement suggested by the etymology of Sheol - Place of judgement.

abstract: Doctor of Philosophy (PhD)


title: Psychosocial Impacts of the Landfill Siting Process in Two Southern Ontario Communities

contributor:
Elliott, Susan J.
Geography

subject: Geography Geography

abstract: In the context of siting waste disposal facilities, recent research suggests that the wellbeing of individuals and communities is impacted as much by the siting process as the outcome itself. The study results presented here stem from an ongoing, two-stage quantitative/ qualitative investigation of impacts of the environmental assessment process on individual and community well-being. This research uses a parallel case-study design to investigate two proposed landfill sites in Southern Ontario. Qualitative approaches (indepth interviews (n=36) and media analysis) were used to address the following objectives: to explore the meaning of the landfill siting process by examining resident concerns; to examine the effects of the siting process by documenting psychosocial effects, coping responses, and perceptions of effects on community; and to examine the role of various information sources in influencing risk perception, effects, and coping. Results indicate substantial impacts on individual and community well-being, including reports of stress, hostility, and divisions within the community. The experience of psychosocial impacts, as well as the effectiveness of both action and emotion-focussed coping strategies, appear to be influenced by perceptions of uncertainty, intensity of concern, and exposure to information sources. Further, the media analysis revealed that impacts were exacerbated by the nature of reporting in the local print media. These findings have implications for the recently revised environmental assessment process in Ontario.

abstract: Master of Arts (MA)


title: On Packet Switch Scheduling in High-Speed Data Networks

contributor:
Szymanski, Ted H.
Electrical and Computer Engineering

subject:
Electrical and Computer Engineering
Electrical and Computer Engineering

abstract:
There is a tremendous demand for Internet core nodes to provide quality-of-service (QoS) guarantees for multimedia services, and to provide high switching capacity that makes use of the virtually unlimited bandwidth of optical fibers. The Internet's Success depends on the deployment of high-speed switches and routers that meet these two demands. We address theoretical and practical aspects of packet switch scheduling in high-speed data networks.

First, we address short-term fairness III QoS scheduling for input-queued (IQ) switches. We show that existing practical scheduling algorithms for Internet routers with IQ switches are unfair over short time scales and potentially lead to increased jitter. Subsequently, we present a scheduling policy based on credit-based fair queueing that provides better short-term fairness in QoS scheduling than existing solutions with comparable complexity. A flow-based iterative credit-based fair scheduler (iCBFS) is proposed for crossbar switches, that provides fair bandwidth distribution among flows at a fine granularity and achieves asymptotically 100% throughput, under uniform traffic. To reduce the implementation complexity of iCBFS, we present a port-based version of iCBFS that is tailored towards high-speed hardware implementation.

Second, we address the problem of fair scheduling of packets in Internet routers with IQ switches and unity speedup. Scheduling in IQ switches is formulated as tracking the behaviour of an output-queued (OQ) switch that provides optimal performance. We present the notion of "lag" as a performance metric that measures the difference between a packet's departure time in an IQ switch over that provided by an OQ switch. We prove that per packet mean lag is bounded for a maximum weight matching scheduling policy that uses lag values for its weights and derive a bound on the mean lag value using a Lyapunov function technique. Furthermore, we propose a simple heuristic tracking scheduling policy and evaluate its performance by simulation.

Finally, we present a novel distributed scheduling paradigm for Internet routers with IQ switches, called Cooperative Token-Ring (CTR) that provides significant performance improvement over existing scheduling schemes with comparable complexity. In classical token-ring based scheduling for IQ switches, a separate token ring (an arbiter) is used to resolve contention for each shared resource (i.e., an output port). Although classical token-ring based scheduling achieves fairness and high throughput for uniform traffic, under non-uniform traffic the performance degrades significantly. We show that by using a simple cooperative mechanism between the otherwise non-cooperative token rings (arbiters) the performance can be significantly improved and the scheduler is able to dynamically adapt to any non-uniform traffic pattern. To provide adequate support for rate guarantees in IQ switches, we present a Weighted Cooperative Token-Ring (WCTR), a simple hierarchical scheduling mechanism. Finally, we analyze the hardware complexity introduced by the proposed CTR scheduling and describe an optimal hardware implementation for an N x N switch implementing a CTR scheduler. We show that the hardware time complexity introduced by the proposed Cooperative mechanism is 8 (log N). iv

abstract: Doctor of Philosophy (PhD)


title: Exact likelihood inference for multiple exponential populations under joint censoring

contributor:
Balakrishnan, Narayanaswamy
Mathematics

subject:
Exponential distribution
Joint progressive Type-II censoring
Joint Type-II hybrid censoring
Joint Type-I hybrid censoring
Likelihood inference
Bayesian inference
Statistical Theory
Statistical Theory

abstract:
The joint censoring scheme is of practical significance while conducting comparative life-tests of products from different units within the same facility. In this thesis, we derive the exact distributions of the maximum likelihood estimators (MLEs) of the unknown parameters when joint censoring of some form is present among the multiple samples, and then discuss the construction of exact confidence intervals for the parameters.

We develop inferential methods based on four different joint censoring schemes. The first one is when a jointly Type-II censored sample arising from $k$ independent exponential populations is available. The second one is when a jointly progressively Type-II censored sample is available, while the last two cases correspond to jointly Type-I hybrid censored and jointly Type-II hybrid censored samples. For each one of these cases, we derive the conditional MLEs of the $k$ exponential mean parameters, and derive their conditional moment generating functions and exact densities, using which we then develop exact confidence intervals for the $k$ population parameters. Furthermore, approximate confidence intervals based on the asymptotic normality of the MLEs, parametric bootstrap intervals, and credible confidence regions from a Bayesian viewpoint are all discussed. An empirical evaluation of all these methods of confidence intervals is also made in terms of coverage probabilities and average widths. Finally, we present examples in order to illustrate all the methods of inference developed here for different joint censoring scenarios.

abstract: Doctor of Science  (PhD)


title: Physical Studies of the Organization and Transcription of the Genome of Human Adenovirus Type 12

contributor:
Mak, S.
Biology

subject: Biology Biology

abstract:
The adenovirus type 12-specific RNA synthesized during productive infection of human cells and in oncogenically transformed rodent cells was studied using the techniques of nucleic acid hybridization. Before the onset of viral DNA replication during productive infection (i.e., early), RNA derived from about 30% of the viral genome was detected in the cytoplasm, while RNA complementary to at least 80% of the genome was detected in the cytoplasm after the onset of DNA replication (late). At both early and late stages of productive infection RNA complementary to a larger fraction of the viral genome was found in the nucleus than in the corresponding cytoplasm, implying the existence of sequence - specific RNA processing and/or transport mechanisms.

The segments of the viral genome encoding early and late cytoplasmic RNA were mapped using subgenomic DNA fragments generated by bacterial restriction endonucleases. A minimum of four separate regions encoding early and late cytoplasmic RNA were positioned by this method.

Two cloned lines of oncogenically transformed rodent cells were found to contain virus specific RNA mapping within the leftmost 17% of the viral genome. Both "early" and "late" classes of cytoplasmic RNA were found in both cell lines. One line contained, in addition, small amounts of RNA encoded within the extreme right hand 9% of the viral genome. The other line contained only RNA derived from the left end of the genome.

The map of the sites on the adenovirus type 12 genome expressed as early and late cytoplasmic RNA deduced during this study is similar, if not identical, to those recently obtained by other workers with the distantly related adenoviruses 2 and 5. This similarity suggests that although the DNA of adenoviruses 12 and 2 share few nucleotide sequences in common, the overall organization of the two genomes is similar.

abstract: Doctor of Philosophy (PhD)


title: Stroke and Left Atrial Appendage Occlusion in Cardiac Surgery

contributor:
Yusuf, Salim
Health Research Methodology

subject:
Atrial Fibrillation
Stroke
Cardiac Surgery
Left Atrial Appendage
Prevention
Surgery
Surgery

abstract:
Stroke is a devastating event for a patient. Patients undergoing cardiac surgery are at risk of both peri-operative and delayed stroke. This thesis comprises 8 chapters that highlight the rate of stroke in cardiac surgery patients and its risk predictors. It justifies the need for a randomized controlled trial of left atrial appendage (LAA) occlusion on top of usual antithrombotic therapy for stoke prevention in patients with atrial fibrillation or flutter.

Chapter 1 is a preface that provides the rationale for undertaking each of the studies included within this thesis.

Chapter 2 presents a large cohort study that examines the predictors of early and long-term stroke in patients undergoing cardiac surgery with emphasis on the impact of atrial fibrillation as well as the CHADS2 score.

Chapter 3 has been published in the journal Circulation in a modified form. A review of the current literature is presented, highlighting that although LAA occlusion holds promise for stroke prevention in AF, there is currently insufficient evidence that it can replace the gold standard of oral anticoagulation.

Chapter 4 is a long-term follow-up study of the first Left Atrial Appendage Occlusion Study. This trial included patients undergoing coronary artery bypass grafting with or without AF. By performing a long-term follow-up of these patients, an estimate of stroke risk and risk of developing new AF was obtained.

In Chapter 5, the results of LAAOS II are presented. This registry and pilot trial was used to assess the rate of recruitment into a novel design of a trial comparing LAA occlusion to antithrombotic therapy, LAA amputation safety, and the rate of a composite outcome of death, myocardial infarction, stroke, non-cerebral systemic emboli, and major bleeding.

Chapter 6 presents the design for the LAAOS III trial. The data presented in the previous chapters is used to create the definitive trial of LAA occlusion on top of usual antithrombotic therapy using a prospective, randomized open trial with blinded end-point study (i.e., PROBE) design.

Chapter 7 presents the health economic analysis plan for LAAOS III.

Finally, Chapter 8 presents the conclusion, limitations, and implications of the research presented in my PhD thesis

abstract: Doctor of Philosophy (PhD)


title: Urban Aboriginal Health: Issues, Culturally Appropriate Solutions and the Embodiment of Self-Determination

contributor:
Warry, Wayne
Dawn Martin-Hill, Dorothy Pawluck
Anthropology

subject:
Aboriginal Health
Traditional Healing
Culturally Appropriate Care
Medical Pluralism
Self Determination
Social and Cultural Anthropology
Social and Cultural Anthropology

abstract:
Urban Aboriginal health and health-related issues are steeped within the sociohistorical, sociocultural, and sociopolitical experiences of Aboriginal peoples since European contact. Thus, urban Aboriginal health issues are very complex in that they consist of aspects associated with collective as well as individual cultural and political life experiences. Therefore, in order to adequately address Aboriginal health issues a comprehensive and multidisciplinary approach is required.

This study examines how Anishnawbe Health Toronto, an urban Aboriginal community health centre, addresses the specific healthcare needs of the urban population through a multidisciplinary culturally appropriate healthcare model. As my research evolved, a few themes emerged from the data. First, the health issues experienced by the clientele were inherently complex and simultaneously infused with a culturally collective and individualistic quality. Second, practitioners acknowledged and addressed the complex nature of the clients’ health problems through a unique model of health care created at the centre. Third, the philosophy, infrastructure, and model of health care at Anishnawbe Health Toronto goes beyond the notion of merely offering access to both systems of health care, and instead constitutes an innovative and culturally appropriate system of care which is under Aboriginal control, development and implementation. Therefore, through my analysis of these themes, I conclude that the model of health care developed at the centre is an example of complex solutions designed to address complex Aboriginal health issues and as a result, facilitate the embodiment of self-determination in the area of health care.

abstract: Doctor of Philosophy (PhD)


title: Acoustic Emission Mapping of Discharges in Spark Erosion Machining

contributor:
Koshy, Philip
Mechanical Engineering

subject:
Acoustic Emission (AE)
Spark Erosion Machining
Electrical Discharge Machining (EDM)
Mapping
Source Location
Manufacturing
Manufacturing

abstract:
Electrical discharge machining (EDM) is a non-conventional machining process utilizing a series of electrical discharges to melt and vaporize workpiece material. In a wire EDM configuration wire breakage is a limiting factor in the machining productivity during the machining of workpieces with varying heights. Present methods of estimating workpiece height on-line in an effort to optimize machining parameters monitor the electrical signals for changes which may not be completely indicative of a change in workpiece height. This thesis intends to utilize acoustic emission (AE) sensors as a method for mapping the discharge location in order to estimate the workpiece height. This represents a novel approach as acoustic emission testing, while prevalent in the process monitoring of numerous conventional machining processes has yet to be significantly studied in combination with EDM.

Another useful application of AE sensors with the EDM process under consideration is during the fast hole EDM process, where excessive wear is seen in the electrode causing true electrode length to remain uncertain. By using acoustic emission sensors to determine the true length of the electrode it could be possible to aid in the breakout detection of the electrode.

abstract: Master of Applied Science (MASc)


title: STATISTICAL AND METHODOLOGICAL ISSUES ON COVARIATE ADJUSTMENT IN CLINICAL TRIALS

contributor: Clinical Epidemiology/Clinical Epidemiology & Biostatistics

subject:
clinical trial
multicentre trial
prognostic imbalance
sample size
propensity score
HIV/AIDS
Biostatistics
Clinical Epidemiology
Clinical Trials
Statistical Methodology
Statistical Models
Survival Analysis
Biostatistics

abstract:
Background and objectives

We investigate three issues related to the adjustment for baseline covariates in late phase clinical trials: (1) the analysis of correlated outcomes in multicentre RCTs, (2) the assessment of the probability and implication of prognostic imbalance in RCTs, and (3) the adjustment for baseline confounding in cohort studies.

Methods

Project 1: We investigated the properties of six statistical methods for analyzing continuous outcomes in multicentre randomized controlled trials (RCTs) where within-centre clustering was possible. We simulated studies over various intraclass correlation (ICC) values with several centre combinations.

Project 2: We simulated data from RCTs evaluating a binary outcome by varying risk of the outcome, effect of the treatment, power and prevalence of a binary prognostic factor (PF), and sample size. We compared logistic regression models with and without adjustment for the PF, in terms of bias, standard error, coverage of confidence interval, and statistical power. A tool to assess sample size requirement to control for chance imbalance was proposed.

Project 3: We conducted a prospective cohort study to evaluate the effect of tuberculosis (TB) at the initiation of antiretroviral therapy (ART) on all cause mortality using Cox proportional hazard model on propensity score (PS) matched patients to control for potential confounding. We assessed the robustness of results using sensitivity analyses.

Results and conclusions

Project 1: All six methods produce unbiased estimates of treatment effect in multicentre trials. Adjusting for centre as a random intercept leads to the most efficient treatment effect estimation, and hence should be used in the presence of clustering.

Project 2: The probability of prognostic imbalance in small trials can be substantial. Covariate adjustment improves estimation accuracy and statistical power, and hence should be performed when strong PFs are observed.

Project 3: After controlling for the important confounding variables, HIV patients who had TB at the initiation of ART have a moderate increase in the risk of overall mortality.

abstract: Doctor of Philosophy (PhD)


title: NOVEL SILICONE-BASED MATERIALS TO LIMIT BACTERIAL ADHESION AND SUBSEQUENT PROLIFERATION

contributor:
Brook, Michael A.
Sheardown, Heather D.
Filipe, Carlos
Biomedical Engineering

subject:
biofilm mitigation
Escherichia coli adhesion
HEMA
BMA
MMA
silicone surfactant
Biomaterials
Biomaterials

abstract: Bacterial biofilms are problematic in a variety of industries hence strategies for their mitigation have received significant attention. The approach described herein attempts to control bacterial adhesion using silicone-based polymers- (widely used due to their interesting properties)- via manipulation of their surface chemistry to eventually create anti-fouling surfaces. This involved study of the systematic variation of surface wettability and its effect on Escherichia coli (E. coli) adhesion to novel polymers of acrylate-modified silicone surfactant (ACR) with either hydroxyethyl methacrylate (a hydrophilic monomer), or methyl and butyl methacrylate (hydrophobic monomers). It was hypothesized that the systematic variation of ACR would produce surfaces with differing wettability, without changing other surface properties that influence cellular adhesion. Average light transmittance across the range of visible light wavelengths (400-740nm), surface roughness and Shore 00 hardness data were consistent across the ACR-HEMA copolymer series (80-90%, ~2.5 – 5 nm, and 75-95 Shore durometer points, respectively). The same consistency was observed for surface wettability (contact angles = 78-92°) despite varying HEMA content and consequently Escherichia coli (E.coli) adhesion, likely due to system saturation with silicon (as confirmed by EDX). However, wettability of the ACR-MMA-BMA polymers did vary; ≤ 20 wt% and ≥ 80 wt% ACR polymers had contact angles between 67°- 77°, while 20 < x < 80 wt% ACR polymers had increased surface wettability (contact angles 27.6°- 42.9°). E. coli adhesion across the set increased with increasing ACR content, a trend mirrored by the water uptake of the materials but not the contact angle data. These results indicate that E. coli adhesion occurs independently of wettability for these materials and although the effect of the latter on adhesion cannot be deduced, the possible correlation between bacterial adhesion and water uptake suggests that the best antifouling surfaces should not be of materials capable of imbibing significant amounts of water.

abstract: Master of Applied Science (MASc)


title: Contextual Usability: The Impact of Distractions and Expectations on Performance, Satisfaction, and Adoption of Mobile Devices for Wireless Data Services

contributor:
Hassanein, K.
Head, M.
Business Administration

subject: Business Administration, Management, and Operations

abstract:
Mobile devices are becoming increasingly popular, having already reached over 1.5 billion mobile subscribers. Such mobile devices propose increasing value to consumers found in "anytime/anywhere" connectivity, communication, and data services. Although progress has been made in terms of technological innovations, many mobile applications remain difficult to use, lack flexibility and robustness. Some key usability challenges facing m-Business (mobile business) applications include limited screen size and quality, limited input methods and navigation difficulties. Additionally, the mobile user has to share his or her attention between the application and the surrounding environment (e.g. visual and/or auditory stimuli). Furthermore, the user's state and personal characteristics (e.g. age, motion) may be key factors in their ability to use a mobile device. This context (i.e. technology, task, environment, and user characteristics) of use may have a significant impact on the usability of such devices.

This dissertation aims to support the claim that context impacts the usability of mobile devices, and in doing so it attempts to answer the following research questions: 1) What is the impact of distractions on the usability of mobile devices for wireless data services? 2) Does Expectancy-Disconfirmation Theory (EDT) help to explain the user's evaluative process of usability with a mobile device for wireless data services? 3) What is the impact of usability on consumers' behavioural intention towards using mobile devices for wireless data services? 4) Which factors become relevant when studying usability within a context of use?

Based on existing research, a framework is proposed and a research model is developed. An empirical study is performed to validate the model and answer the research questions outlined. To simulate a real-world setting where the context of using a mobile device is constantly changing, a laboratory experiment (2x2 factorial design) was performed involving 93 subjects. Distractions were simulated in this study in the form of either user motion or environmental noise (i.e. background auditory and visual stimuli). A structural equation modelling analysis confirmed the impacts of distractions on perceived usability (i.e. efficiency and effectiveness) of, and in turn the users' behavioural intention to use, a mobile device for wireless data services. The applicability of the Expectancy-Disconfirmation Theory (EDT) in explaining a mobile user's evaluative process of usability was also explored and was found moderately significant in explaining the impact of user expectations of perceived performance.

This dissertation contributes to theory and enhances our understanding of usable mobile devices for wireless data services. Implications for practice with respect to both interface design for mobile devices and marketing of mobile services are also presented.

abstract: Doctor of Philosophy (PhD)


title: THE EFFECT OF LIFESTYLE FACTORS ON POTENTIAL MEASURES OF NEUROGENESIS AND THE BEHAVIOURAL IMPLICATIONS

contributor:
Becker, Suzanna
Psychology

subject:
neurogenesis
memory
neuroscience
Cognitive Psychology
Cognitive Psychology

abstract:
Over long delays between events, evidence from computational models suggests that neurogenesis may be important for reducing the potential of interference between overlapping memories. These computational models also suggest that at shorter time scales, within a single memory episode, neurogenesis may play a role in binding together elements that share a common spatiotemporal context. Empirical evidence from animal research provides support for both of these hypothesized roles. Interestingly, results from recent research also suggest that depending on the task demands, neurogenesis may either aid or hinder performance.

In order to investigate this potential trade-o, we designed the Concentration Memory Task (CMT); a novel spatial memory task which subjected participants to trials where neurogenesis is hypothesized to aid performance and trials where neurogenesis is hypothesized to hinder performance. Furthermore, we tested undergraduates on this novel task and memory tests from the CANTAB battery, and administered neuropsychological mood inventories and a lifestyle questionnaire.

Our results suggest that measures on the CMT hypothesized to be dependent upon neurogenesis correlate with and predict performance on putatively neurogenesis-dependent tasks. Furthermore, individuals with potentially suppressed neurogenesis display selective decits on these measures. However, our results failed to provide evidence for a working memory enhancement in these individuals.

The results from the present study provide strong encouragement for the continued development of this novel task. We provide evidence that as predicted, individuals with potentially suppressed neurogenesis display increased sensitivity to interference on the CMT. However, we failed to provide evidence that suppressed neurogenesis may enhance working memory performance. This null result may be due to shortcomings in the design of the CMT and a revised protocol that may resolve these shortcomings is discussed. With continued development, the CMT may serve as a tool for detecting early signs of cognitive impairment associated with suppressed neurogenesis.

abstract: Master of Science (MSc)


title: Advanced Materials and Fabrication Methods for Electrochemical Supercapacitors

abstract:
The electrochemical supercapacitors (ESs) are an emerging technology that promises to play an important role in meeting the demands of automotive and electronic industry. A notable improvement in ES performance has been achieved through recent advances in understanding charge storage mechanisms and the development of advanced nanostructured materials, such as nanostructured MnO2 and composites.

The anodic electrophoretic deposition (EPD) method has been developed for the fabrication of MnO2 and composite MnO2-multiwalled carbon nanotubes (MWCNTs) films. The problem of low stability of MnO2 suspensions was addressed by the development of new dispersing agents. Benzoic acid and phenolic molecules, such as 3,4-dihydroxybenzoic acid, 3,4-dihydroxyphenylacetic, 3,4-dihydroxyhydrocinnamic acid, 3,4,5-trihydroxybenzoic acid, salicylic acid, 2,3,4-trihydroxybenzoic acid, aurintricarboxylic acid and aurintricarboxylic acid ammonium salt were investigated as additives for the dispersion and charging of MnO2 nanoparticles. The adsorption of the organic molecules on the MnO2 nanoparticles involved the interaction of COOH groups and OH groups with Mn atoms on the particle surfaces and complexation. The results showed that adjacent OH groups, as well as adjacent OH and COOH groups bonded to the aromatic ring of the phenolic molecules enabled enhanced adsorption of the organic molecules. It was found that EPD of MnO2 and MWCNTs can be achieved using 3,4-dihydroxybenzoic acid, 2,3,4-trihydroxybenzoic acid, and aurintricarboxylic acid as a common dispersants and charging additives.

Aurintricarboxylic acid ammonium salt provided a charge required for efficient dispersion and EPD of MWCNTs and graphene.

New dispersion methods allowed the formation of composite electrodes by colloidal techniques, such as EPD or slurry impregnation of MnO2 and MWCNTs into advanced current collectors, such as porous nickel foam and nickel plaque. The composite electrodes showed excellent capacitive performance with large material loading in 0.5 M Na2SO4 electrolyte. MnO2 and MWCNTs can form a porous network, which is beneficial for the electrolyte access to the active materials. The effect of the MWCNTs concentration, scan rate and electrodes type on the capacitive behaviour was discussed. It was found that the addition of MWCNTs can improve the capacitive performance of MnO2 electrodes and reduced equivalent series resistance.


title: A FAULT DETECTION AND DIAGNOSIS STRATEGY FOR PERMANENT MAGNET BRUSHLESS DC MOTOR

contributor:
Habibi, Saeid
Stephen Veldhuis, Samir Ziada
Mechanical Engineering

subject:
Motor
Wavelet
BLDC
Kalman filter
Estimation
Fault detection and diagnosis
Electro-Mechanical Systems
Electro-Mechanical Systems

abstract:
Unexpected failures in rotating machinery can result in production downtime, costly repairs and safety concerns. Electric motors are commonly used in rotating machinery and are critical to their operation. Therefore, fault detection and diagnosis of electric motors can play a very important role in increasing their reliability and operational safety. This is especially true for safety critical applications.

This research aims to develop a Fault Detection and Diagnosis (FDD) strategy for detecting motor faults at their inception. Two FDD strategies were considered involving wavelets and state estimation. Bearing faults and stator winding faults, which are responsible for the majority of motor failures, are considered. These faults were physically simulated on a Permanent Magnet Brushless DC Motor (PMBLDC). Experimental results demonstrated that the proposed fault detection and diagnosis schemes were very effective in detecting bearing and winding faults in electric motors.

abstract: Master of Applied Science (MASc)


title: LIKELIHOOD INFERENCE FOR LEFT TRUNCATED AND RIGHT CENSORED LIFETIME DATA

contributor:
Balakrishnan, Narayanaswamy
R. Viveros, Aaron Childs
Mathematics and Statistics

subject:
Lifetime data
Left truncation
Right censoring
Likelihood inference
EM algorithm
Missing information principle
Physical Sciences and Mathematics
Statistical Methodology
Physical Sciences and Mathematics

abstract: Left truncation arises because in many situations, failure of a unit is observed only if it fails after a certain period. In many situations, the units under study may not be followed until all of them fail and the experimenter may have to stop at a certain time when some of the units may still be working. This introduces right censoring into the data. Some commonly used lifetime distributions are lognormal, Weibull and gamma, all of which are special cases of the flexible generalized gamma family. Likelihood inference via the Expectation Maximization (EM) algorithm is used to estimate the model parameters of lognormal, Weibull, gamma and generalized gamma distributions, based on left truncated and right censored data. The asymptotic variance-covariance matrices of the maximum likelihood estimates (MLEs) are derived using the missing information principle. By using the asymptotic variances and the asymptotic normality of the MLEs, asymptotic confidence intervals for the parameters are constructed. For comparison purpose, Newton-Raphson (NR) method is also used for the parameter estimation, and asymptotic confidence intervals corresponding to the NR method and parametric bootstrap are also obtained. Through Monte Carlo simulations, the performance of all these methods of inference are studied. With regard to prediction analysis, the probability that a right censored unit will be working until a future year is estimated, and an asymptotic confidence interval for the probability is then derived by the delta-method. All the methods of inference developed here are illustrated with some numerical examples.

abstract: Doctor of Philosophy (PhD)


title: Models for the morphology and morphogenesis of the ammonoid shell

contributor:
Westermann, G.E.G.
Geology

subject: Geology Geology

abstract: The process of accretionary growth in molluscs is examined and a new growth equation suitable for accretionary growth is proposed and derived. The morphology of the shell in the Ammonoidea (Mollusca, Cephalopoda) is described and the morphogenesis simulated by means of theoretical models. In the case of the characterization of morphology, the shell is described by a set of objective descriptors that can be used in taxonomy. The morphogenesis of the ammonoid shell is explained in terms of static equilibrium of the secreting mantle and a diffusive process that mediates the actual precipitation of shell material on the growing edge of the shell. Different morphologies arise from varying the boundary conditions in the resulting differential equations.

abstract: Doctor of Philosophy (PhD)


title: The Influence of Surface Conditions in Nucleate Boiling

contributor:
Judd, Ross L.
Mechanical Engineering

subject:
Mechanical Engineering
Mechanical Engineering

abstract:
A theoretical and experimental study of the influence of surface conditions in nucleate boiling is presented. The surface conditions are represented by the density and distribution of the active nucleation sites as well as the size distribution of the cavities which constitute the nucleation sites.

One of the important boiling parameters known to be a function of the nucleation cavity size is the frequency of bubble departure. A theoretical model is formulated to predict the bubble frequency as a function of the nucleation cavity radius as well as the surface superheat and liquid subcooling in which the time variations of the surface temperature throughout the bubble cycle are incorporated. Parametric study of this model shows that the frequency of bubble departure decreases with decrease of surface superheat and increase of liquid subcooling, a trend which agrees with the published data. It is also shown that smaller nucleation cavities are able to emit vapour bubbles with higher frequency than that corresponding to larger cavities. Experimental results obtained by boiling water and isopropyl alcohol on a single copper surface having two different surface finishes showed good agreement with the theoretical model.

In addition, the concept of the bubble flux density is introduced. The bubble flux density is defined as the rate of bubble emission per unit area of the boiling surface and a method of evaluating it as a function of bubble frequency and active site distribution is proposed. A uniform correlation between the boiling heat flux and the bubble flux density is found to exist for a particular solid-liquid combination irrespective of the surface finish within the region of isolated bubbles.

abstract: Doctor of Philosophy (PhD)


title: Modelling Fault Tolerance using Deontic Logic: a case study

contributor:
Maibaum, Tom
Ryan Leduc, Emil Sekerinski
Computing and Software

subject:
Fault Tolerance
Deontic Logic
Modal Logic
High Level Modelling
First Order Logic
Computational Engineering
Other Computer Engineering
Computational Engineering

abstract:
Many computer systems in our daily life require highly available applications (such as medical equipment) and some others run on difficult to access places (such as satellites). These systems are subject to a variety of potential failures that may degrade their performance. Therefore, being able to reason about faults and their impact on systems is gaining considerable attention. Existing work on fault tolerance is mostly focused on addressing faults at the programming language level. In the recent past, significant efforts have been made to use formal methods to specify and verify fault tolerant systems to provide more reliable software. Related with this, some researchers have pointed out that Deontic Logic is useful for reasoning about fault tolerant systems due to its expressive nature in relation to defining norms, used to describe expected behaviour and prescribing what happens when these norms are violated.

In this thesis, we demonstrate how Deontic Logic can be used to model an existing real world problem concerning fault tolerance mechanisms. We consider different situations that a vehicle faces on the road and the consequent reactions of the driver or vehicle based on good and bad behaviour. We got the idea and motivation for this case study from the SASPENCE sub-project, conducted under the European Integrated Project PReVENT. This sub-project focuses on a vehicle’s behaviour in maintaining safe speed and safe distance on the road. As our first modelling attempt, we use a Propositional Deontic Logic approach, to justify to what extent we can apply this Logical approach to model a real world problem. Subsequently, we use a First Order Deontic Logic approach, as it can incorporate the use of parameters and quantification over them, which is more useful to model real world scenarios.

We state and prove some interesting expected properties of the models using a First Order proof system. Based on these modelling exercises, we acquired different engineering ideas and lessons, and present them in this thesis in order to aid modelling of future fault tolerant systems.

abstract: Master of Science (MSc)


title: SIGNIFICANCE OF ION INDUCED LUMINESCENCE FOR RADIATION INDUCED BYSTANDER EFFECTS

contributor:
McNeill, Fiona E.
Mothersill, Carmel E.
Byun, Soo-Hyun
Medical Physics

subject:
Luminescence
UV
Bystander effects
Microbeams
PIXE
Other Physics
Other Physics

abstract:
Radiation induced bystander effects have given the cancer risk analysis a whole new paradigm. However the actual mechanism involved in producing the effects is still not clear. The basic bystander signal is assumed to be a biological signal. In this study we proposed and tried to quantify the presence of a physical signal in the form of electromagnetic radiation that can trigger a biological response in the bystander cells. In bystander effect studies where the cells are exposed to very low fluence of charged particles there could be several regions that can produce electromagnetic radiation due to the process of atomic/molecular excitations and relaxations. We focused on quantifying the number of ultraviolet photons emitted when charged particles pass through different media that have relevance to radiation biology experiments. The choice of UV photons was made due to the reason that its effects on living cells are very well documented. For this purpose we developed a system which employed the technique of single photon counting to measure the light emitted from samples irradiated under vacuum by a charged particle beam. Photon counting was done using a fast photomultiplier tube (Hamamatsu R7400p) with a peak cathode response at 420 nm wavelength.

In the early set of “proof of principle experiments” we tested polystyrene targets for ion beam induced luminescence. Polystyrene is one of the materials that are used as a cell substrate for radiation biology experiments. The luminescence yield from polystyrene was measured in terms of absolute value i.e. number of photons per second per unit solid angle. The output appeared to have a non-linear behavior with the incident Ion fluence: it rose exponentially to an asymptotic value. We irradiated the samples with beam energies varying from 1 MeV to 2.0 MeV and showed saturation at or before an incident fluence rate of 3×1013 H+/cm2s. The average saturation value for the photon output was found to be 40 × 106 cps. Some measurements were performed using filters to study the emission at specific wavelengths. In the case of filtered light measurements, the photon output was found to saturate at 28×103, 10×106, and 35×106 cps for wavelengths of 280±5 nm, 320±5 nm and 340±5 nm respectively. Using the IBIL signal evolution characteristics with the ion fluence we determined the ions produce a damage having a cross section of the order of 10-14 cm2 in polystyrene. The average radiant intensity was found to increase at wavelengths of 280 nm and 320 nm when the proton energy was increased. Having found an evidence of a significant production of UV in ion irradiated, biologically relevant, material we extended this study further into the measurements from other relevant materials in radiation biology.

Here charged particle irradiation was performed using positively charged protons (H+) ranging in energy from 1.2 MeV to 2.2 MeV at a fluence rate of 2.7×1010 protons mm-2s-1.The materials chosen for this study were polypropylene, Mylar, Teflon, and Cellophane as they are all materials commonly used in radiation biology experiments as cell substrates or containers. In addition, we performed measurements of two NIST standard materials derived from living cells: oyster tissue and citrus leaves. These materials were measured as a powder.

All the container materials were found to emit UV frequency photons at emission levels that are significant enough to warrant further investigation of the potential biological consequences. In addition, the NIST standard reference materials oyster tissue and citrus leaves also emitted UV when irradiated. This suggested that biological materials may themselves emit UV at significant levels when irradiated with charged particles.

We established this further by irradiated cells with β-particles. Cells were plated in Petri-dishes of two different sizes, having different thicknesses of polystyrene (PS) substrate. Exposure of the cell substrates (polystyrene) only resulted in the production of 1035 photons per unit activity in μCi of 90Y which was equivalent to an exposure of 840 β-particles/cm2 to the substrate. For a collimated electron beam exposure, we observed 158-167 photons per unit μCi (18 β-particles per cm2 on the substrate) for different thicknessesof the substrate. Upon irradiating HPV-G cells plated on the PS dishes we determined that the luminescence gradually increased with the increasing exposure of β-particles; reaching up to 250 % of that of the luminescence without any cells for an activity of 180 μCi. For general irradiation conditions we found statistically significant difference in luminescence output for varying cellular densities with cells only and with the application of medium on top of the cells. The colourless medium increased the total luminescence yield while the coloured medium decreased it. When the cells were irradiated using a collimated beam of electrons it was found that the luminescence decreases with the increasing cellular density thus providing an evidence of re-absorption of photons within the surroundings.

After establishing the fact that charged particles induce light emission from the materials that have a relevance to the radiation biology experiments. We extended our study further to find out other sources of radiation that could affect the dose distribution in radiation biology experiments. In radiation biology experiments the low doses of radiation are usually delivered usingamicrobeam charged particle accelerator. Microbeams delivers a highly localized and small dose to the biological medium by using a set of collimators that confine the charged particle beam to a very narrow (micron level) region. Since the collimation block a significant proportion of the beam therefore there is a chance of the production of low energy x-rays and secondary electrons. We used Monte Carlo simulations to investigate the production of particle induced x-rays and secondary electrons in the collimation system and its possible effects on the final dose delivery to the biological medium. We found no evidence of the escape of x-rays or secondary electrons from the collimation system for proton energies of up to 3 MeV. The thickness of the collimators was sufficient to reabsorb all the generated low energy x-rays and secondary electrons. However if the proton energy exceeds 3 MeV then a significant proportion of 10 keV and 59 keV (K-α) x-rays can be emitted by the collimator. Further it was established that due to the phase space distribution of particles in various orientations with the beam axis there are significant chances of hitting non-targetted cells in microbeams that employ a collimator to confine the beam.This may happen due to the beam particles travelling obliquely with the beam axis thus passing the collimator edge and hitting the non-targetted cells. Another reason could be the scatter of beam particles inside the collimator.

The evidence of the production of UV in materials relevant to the radiation biology experiments suggest that the conclusions and hypotheses derived from some radiation bystander experiments need to be re-thought, as charged particle irradiation leads to some level of UV emission in experimental materials which may be the cause of some “non-targeted” effects.

abstract: Doctor of Philosophy (PhD)


title: MULTIRESOLUTION-MULTIVARIATE ANALYSIS OF VIBRATION SIGNALS; APPLICATION IN FAULT DIAGNOSIS OF INTERNAL COMBUSTION ENGINES

contributor:
Habibi, Saeid
Ziada, Samir
Mechanical Engineering

subject:
DWT
PCA
MSPCA
CAD
Fault Diagnosis
Engine
Wavelet
Acoustics, Dynamics, and Controls
Acoustics, Dynamics, and Controls

abstract: Condition monitoring and fault diagnosis of mechanical systems are two important issues that have received considerable attention from both academia and industry. Several techniques have been developed to date to address these issues. One category of these techniques which has been successfully applied in many industrial plants is based on the multiresolution multivariate analysis algorithms and more specifically the multi-scale principal component analysis (MSPCA). The present research aims to develop a multi-resolution multivariate analysis technique which can be effectively used for fault diagnosis of an internal combustion engine. Crank Angle Domain (CAD) Analysis is the most intuitive strategy for monitoring internal combustion engines. \comment{ as a cyclic system in which events at each cycle is correlated to a particular position of the crankshaft, this leads to analyzing the engine performance in angle domain (i.e. Crank Angle domain for engine) as very logical and intuitive strategy.} Therefore, MSPCA and CAD analysis were combined and a new technique, named CAD-MSPCA, was developed. In addition to this contribution, two indices were defined based on estimation of covariance matrices of scores and fault matrices. These indices were then employed for both fault localization and isolation purposes. In addition to this development, an interesting discovery made through this research was to use the statistical indices , calculated by MSPCA, for fault identification. It is mathematically shown that in case these indices detect a fault in the system, one can determine the spectral characteristics of the fault by performing the spectrum analysis of these indices. This analysis demonstrated the MSPCA as an attractive and reliable alternative for bearing fault diagnosis. These new contributions were validated through simulation examples as well as real measurement data.

abstract: Master of Applied Science (MASc)


title: L2 Optimized Predictive Image Coding with L∞ Bound

contributor:
Wu, Xiaolin
Electrical and Computer Engineering

subject:
L∞-constrained image compression
predictive coding
optimal scalar quantization
Signal Processing
Signal Processing

abstract: In many scientific, medical and defense applications of image/video compression, an l∞ error bound is required. However, pure l∞-optimized image coding, colloquially known as near-lossless image coding, is prone to structured errors such as contours and speckles if the bit rate is not sufficiently high; moreover, previous l∞-based image coding methods suffer from poor rate control. In contrast, the l2 error metric aims for average fidelity and hence preserves the subtlety of smooth waveforms better than the l∞ error metric and it offers fine granularity in rate control; but pure l2-based image coding methods (e.g., JPEG 2000) cannot bound individual errors as l∞-based methods can. This thesis presents a new compression approach to retain the benefits and circumvent the pitfalls of the two error metrics.

abstract: Master of Applied Science (MASc)


title: ENCAPSULATION OF FACTOR IX-ENGINEERED MESENCHYMAL STEM CELLS IN ALGINATE-BASED MICROCAPSULES FOR ENHANCED VIABILITY AND FUNCTIONALITY

contributor:
Hortelano, Gonzalo
Biomedical Engineering

subject:
cell encapsulation
alginate
biomimetic microcapsules
mesenchymal stem cells
hemophilia B
Biomaterials
Biomaterials

abstract:
The work presented in this thesis was focused on design and construction of novel cell-loaded microcapsules by incorporation of bioactive molecules (proteins or peptides) for potential application in hemophilia B treatment. The objective of this study was to improve the viability and functionality of the encapsulated cells by creating biomimetic microenvironments for cells that more closely mimic their physiological extracellular matrix (ECM) environment.

Three cell-adhesive molecules were used in this work: fibrinogen and fibronectin, two abundant proteins present in ECM, and arginine-glycine-aspartic acid (RGD) tri-peptide, the minimal essential cell adhesion peptide sequence and the most widely studied peptide for cell adhesion. Alginate, the most commonly used biomaterial used for cell encapsulation, was combined with either of these molecules to create biomimetic microcapsules. Non-modified alginate (control) and modified alginate matrices were used to encapsulate the factor IX (FIX) secreting cells for protein delivery. In this work, FIX-engineered cord blood-derived human mesenchymal stem cells CB MSCs were used as a cell source for FIX delivery.

Our data suggested that fibrinogen-alginate, fibronectin-alginate and RGD-alginate microcapsules improved the viability of encapsulated MSC and are applicable in cell therapy technologies. However, fibrinogen-alginate and fibronectin-alginate microcapsules more significantly enhanced the proliferation and protein secretion from the encapsulated cells and may have potential for FIX delivery for hemophilia B and other inherited or acquired protein deficiencies. RGD-alginate microcapsules can v potentially be used for other tissue engineering applications with the aim of enhanced viability and attachment of the enclosed cells. Differentiation studies showed the osteogenic (but not chondrogenic or adipogenic) differentiation capability of FIX-engineered CB MSCs and their efficient FIX secretion while encapsulated in fibrinogen-alginate and fibronectin-alginate microcapsules.

abstract: Doctor of Philosophy (PhD)


title: Literacy, Identity and the Educational Effect

contributor:
McKerrow, Mark
Charlene Maill, Scott Davies
Sociology

subject:
literacy
education
identity
status passage
Educational Sociology
Social Psychology and Interaction
Educational Sociology

abstract:
Using semi-structured interviews, this research brings to light the lived experiences of thirteen people participating in adult literacy programs. Despite the popularization of situated approaches to literacy in pedagogical models and practice in the field of adult basic education, few studies have emphasized the role of identity in shaping the educational experience and its effects. Symbolic interactionism offers a theoretical map from which to examine the varied experiences of adult literacy learners.

Gaining insight into learners’ negotiation of a literate identity yields a nuanced appreciation for how the experience takes shape as part of the broader processes that adults undertake as they seek access to the literate world. Three distinct pathways were identified in learners’ reasons for signing up for, and participating in, the literacy programs: the role fulfillment pathway, the personal betterment pathway and the instrumental pathway. Acquiring a literate identity had differing effects for learners on each pathway either by allowing them to fulfill socially desirable roles through status passage, by acquiring a more positive self-concept, or by acquiring the knowledge and skill to independently accomplish specific tasks.

Introducing identity change to the literature on the effect of adult education offers a twofold benefit. First, identity change can motivate adults’ investments in education and, more so than earnings as instrumental models predict, reflects the actual experience of adult learners. Second, identity change may be a mechanism through which education has its diverse effects on a variety outcomes.

Though one might assume that those with higher educational and employment goals benefit the most from literacy programs, it appears to be the opposite: those who seem the least likely to pursue education derive the greatest benefit – a finding akin to studies of broader educational effects. Implications for future research of the mechanisms by which these effects manifest themselves as well as considerations for policy development in adult literacy are discussed.

abstract: Master of Arts (MA)


title: Understanding Magnetosome Formation and Organization using Scanning Transmission X-ray Microscopy – X-ray Magnetic Circular Dichroism

contributor:
Hitchcock, Adam P.
Goward, Gillian
Mozharivskyj, Yurij
Chemistry and Chemical Biology

subject:
STXM
Magnetotactic Bacteria
XMCD
X-ray Microscopy
Biomagnetism
NEXAFS
Biogeochemistry
Materials Chemistry
Other Chemistry
Biogeochemistry

abstract:
Magnetotactic bacteria (MTB) are ubiquitous, multi-phylogenetic bacteria that actively synthesize chains of magnetic, membrane bound; single domain magnetite (Fe3O4) or greigite (Fe3S4) crystals, termed magnetosomes in order to better navigate to their preferred chemical environment using the Earth’s magnetic field. Discovered in 1963, the field is now focused on understanding magnetosome chain formation and associated processes through genetic studies as well as analytical techniques such as Transmission Electron Microscopy (TEM) and Scanning Transmission X-ray Microscopy – X-ray Magnetic Circular Dichroism (STXM-XMCD).

This thesis performed studies on Candidatus Magnetovibrio blakemorei strain MV-1 using STXM at the C 1s, O 1s, Ca 2p and Fe 2p edges. STXM-XMCD was used to determine the magnetism of individual magnetosomes and quantitatively determine magnetic properties such as the magnetic moment of individual chains. A sub-population of MV-1 cells was identified as having anomalous magnetic orientations of magnetosome sub-chains when separated spatial gaps. The frequency of this event and the underlying implications to magnetosome formation are discussed.

abstract: Master of Science (MSc)


title: Artificial Intelligence in Simulations

contributor:
Mohrenschildt, Martin v.
Computing and Software

subject: Artificial Intelligence Presagis Simulation

subject: Computational Engineering

subject: Other Computer Engineering

subject: Computational Engineering

abstract: Simulator systems are becoming increasingly popular within the automotive industry. Driving simulations are used to train new drivers, and to research and improve automobile related technologies. While recent technological advances have made simulators more affordable, they have also made simulators more complex. At McMaster's motion simulator laboratory, we wished to create a system to analyze how drivers behave when behind the wheel in a variety of situations. To accomodate this, we have created a complex, robust system capable of presenting the driver with customized scenarios, and measuring their reactions to those scenarios using a variety of standard psychology techniques, such as EEG. Our system utilizes a variety of software components such as scenario management, artificial intelligence, image generation, and content creation. This thesis describes the use of one software component, the Presagis AI.implant. The AI.implant is an artificial intelligence system used to control autonomous characters within the simulation, which the driver can interact with. The AI.implant has also been extended to allow for more possible experiment scenarios, and to improve the quality of the simulation. These extensions include: the addition of signal lights for vehicles, emergency vehicle characters, and improved character movement at intersections. This thesis demonstrates that an artificial intelligence is a useful component of a more complex simulation, in order to promote further research in this field.

abstract: Master of Applied Science (MASc)