title: The Association of Hemispheric Specialization and Cognitive Abilities with Regard to Sex, Hand Preferences and Birth Stress

subject:
Medical Sciences
Medical Sciences

abstract:
The relationship of patterns of hemispheric specialization to verbal and non-verbal cognitive abilities were studied as well as the effects of birth stress on the etiology of left-handedness. Using verbal and non-verbal dichotic listening tests 28 right- and left-handed boys and girls with a mean age of 10.6 years, were assessed as being unilaterally or bilaterally organized for processing verbal and non-verbal material. The subjects were also assessed for verbal and non-verbal ability using standard intelligence tests. Birth records were obtained in order to assess whether birth stress resulted in perinatal anoxia, the agent for altering hand preference. It was found that:

1) Boys may show a left ear effect for some nonverbal material but girls may not.

2) Bilateral organization for processing non-verbal material is not necessarily correlated with poorer spatial ability in girls.

3) The relationship of bilateral organization for processing verbal material with overall verbal ability were inconclusive.

4) There is no evidence to indicate that birth stress and/or oxygen deficit are necessary for left-handedness to occur, since both right- and left-handers exhibit these factors to the same degree and at least some of the left-handers appear to show no evidence of birth stress at all.

abstract: Master of Science (MS)


title: Intrinsic degradation mechanism in tris(8-hydroxyquinolato) aluminum-based organic light emitting devices

contributor:
Popovic, Zoran D.
Materials Science and Engineering

subject:
Materials Science and Engineering
Materials Science and Engineering

abstract: Intrinsic degradation, which leads to the long-term decrease in the electroluminescence efficiency, has been a major limitation facing the new technology of organic light emitting devices (OLED). Traditionally, degradation has been speculated to be caused by morphological instability of the organic layers, especially the less stable hole transport layer (HTL), or by the formation of deep traps at the hole-injecting contact. These speculations were based on experimental observations showing that doping the organic layers or introducing a buffer layer at the hole-injecting contact can dramatically improve device stability. However, the real causes of OLED degradation remained uncertain. In this study, the cause of the long-term degradation of OLEDs based on tris(8-hydroxyquinolato) aluminum (A1Q3), the most widely used electroluminescent molecule, is investigated. OLEDs with various structures are studied. Results reveal that the injection of holes into the AlQ3 layer is the dominant factor responsible for device degradation. Cationic AlQ3 species are found to be unstable and their degradation products are fluorescence quenchers that lower the electroluminescence efficiency of OLEDs. In view of these findings, the effectiveness of stabilizing agents, such as, doping the HTL, introducing a buffer layer at the hole-injecting contact, or using mixed layers of hole and electron transporting molecules, is explained in terms of their role in slowing down the injection of holes into the AlQ 3 , which results in a higher electron density and thus a more rapid electron-hole recombination. Therefore, the lifetime of the unstable cationic AlQ3 species is reduced leading to a significant decrease in AlQ 3 degradation and consequently increases device stability. Other earlier observations pertaining to OLED degradation are also addressed. The degradation mechanism is further demonstrated on OLEDs with dual-layer HTL made of materials with different ionization potentials. The important features of a theoretical framework to model OLED degradation are also discussed.

abstract: Doctor of Philosophy (PhD)


title: Separation of components in waste oxides by evaporation and condensation under reduced pressure

contributor:
Lu, W-K.
Materials Science and Engineering

abstract: Steelmaking dust is generated in high temperature refining step at a rate of about 2% of the steel produced. Electric Arc Furnace (EAF) dust is classified as a hazardous material due to its content of leachable heavy metals, i.e., Pb, Cd, and Cr. Therefore, it must be treated before disposal to meet certain environmental regulations. Most processes for the treatment of EAF dust involve recovery of valuable metals, such as zinc. In most cases alkali halides and lead in the dust are problematic in both processing and product quality. In the present work a pre-treatment is proposed to separate "more volatile species" which include the alkali halides, lead compounds and cadmium oxide, from "less volatile species" which include iron, zinc and calcium oxides. Evaporation of volatile species in this process takes place at about 900° C in a virtually closed system under reduced pressure, and condensation of the vapors occurs at a lower temperature. The thermodynamic aspects of the process are considered. With the use of three different experimental apparatuses the kinetics of the system are studied. The rate of individual kinetic steps; evaporation, condensation, heat and mass transfer, are calculated and compared with the observed overall rate of reaction. A numerical model for the heat transfer inside the dust bed is developed. Applying the principles of mass and heat transfer to the system under investigation, and using the results of the experiments and the numerical model of heat transfer, it is shown that heat transfer across the porous dust bed is most likely the rate controlling step. A rotary reaction chamber is designed to facilitate the heat transfer to dust particles and eliminate the slow kinetic step of heat transfer across the stationary dust bed. With the use of the rotary reaction chamber the duration of treatment is significantly reduced under otherwise identical conditions. The benefit of the rotational movement may be appreciated by direct comparison of the treatment of twenty five grains EAF dust. At a furnace temperature of 1100°C for 95% removal of the volatile species the time required (from the introduction of the apparatus at 25°C to its withdrawal from the furnace) is 12 minutes for the stationary and 8 minutes for the rotational chamber. At a lower furnace temperature of 950°C , the degrees of removal of lead and potassium are about 51% and 27% for 12 minutes in the stationary reaction chamber and about 83% and 78% for 10 minutes in the rotary reaction chamber. A secondary incinerator dust is also investigated in the present work. In 6 minutes at a furnace temperature of 950°C about 99% of the volatile species including NaCl , KCl , and lead compounds are removed from twenty five grams dust. The residue has an enrichment of zinc from 27%wt to 78%wt . This environmentally friendly and energy efficient process may be applicable for the separation of "more volatile species" in dust generated from most high temperature processes such as steelmaking, incineration, nonferrous processes and cement manufacturing.

abstract: Doctor of Philosophy (PhD)


title: Title Relative Numerical Ranges of Elements of Banach and L.M.C.-Algebras

contributor:
Husain, T.
Mathematics

subject:
Algebra
Mathematics
Physical Sciences and Mathematics
Algebra

abstract:
This study examines what growing old means for the older women's sense of self-identity. Some gerontologists argue that old age constitutes a period of role loss with detrimental impact on identity. A sizable body of data do not support this assumption. The underlying assumption of this study is that identity emerges and is sustained through social interaction. Thus the research focuses on (1) the meaning of 'being old' as defined by older women and (2) the extent to which a positive identity can be retained through social network involvement with family, friends and community leisure activities. Instead of focusing on what is lost, the emphasis was on determining what role relationships are retained and established in old age, and the extent to which these serve to maintain a positive self image.

The research is based on interviews with 142 women over age 65 living in the town of Bridgewater, Nova Scotia. The principle component of this sample comprised 101 women living in their own homes or apartments (i.e. community- dwelling). Most of the analysis is based on this sample. However, where comparative analysis is useful, these data are supplemented with information from interviews with 31 residents of senior citizen apartment complexes and 10 residents of a nursing home. The findings indicate that the elderly women studied here generally do not view themselves as 'elderly' or 'old'. Age identity is found to be largely situational and more relevant to some interactions than others. The majority have managed to retain a positive identity which is deeply embedded within their informal role involvements and social network ties. As a result, the loss of more formal role relationships had only limited impact on identity. The findings also indicate that a relatively stable small community appears to offer advantages for identity management in old age.

abstract: Doctor of Philosophy (PhD)


title: The role of bone marrow progenitor cells in allergen-induced airway hyperresponsiveness and airway inflammation

contributor:
Denburg, J.A.
Janssen, L.
Physiology and Pharmacology

subject: physiology pharmacology

abstract: Asthma is a disease characterised by reversible bronchoconstriction, airway hyperresponsiveness (AHR) and airway inflammation. Inhalation of allergen by sensitized subjects is an important cause of asthma, and results in an increase in the numbers of inflammatory cells, more specifically the eosinophil, in the airways. An important aspect of allergic inflammatory responses is the induction of increases in inflammatory cell progenitors, which contribute to disease through the continued production of inflammatory cells. Higher numbers of circulating eosinophil/basophil progenitors are demonstrable in the blood of atopic subjects compared with normals, and in asthmatic subjects following allergen inhalation. In addition, there are increases in bone marrow progenitor cells following allergen inhalation in a canine model of allergen-induced AHR. Although these studies suggest that inflammatory cell progenitors in the blood arise from the bone marrow, this had not been shown in humans. The aim of this thesis was to examine the role of bone marrow inflammatory cell progenitors in allergen-induced AHR and airway inflammation, with respect to increased production and trafficking of these cells. In addition, the effect of therapeutic intervention with inhaled glucocorticosteroids was investigated. We demonstrated, for the first time, that increases in bone marrow-derived eosinophil/basophil progenitors occurred 24 hours following allergen inhalation in mild asthmatic subjects through up-regulation of the IL-5 receptor on progenitors, and that the degree of responsiveness of these cells was associated with the magnitude of the eosinophilic response in the airways. In addition, we demonstrated an increase in the trafficking of inflammatory cell progenitors, from the bone marrow through the circulation, into the airways, suggesting that the increased production of these cells can contribute to the ongoing inflammatory response. Finally, we showed that inhalation of the glucocorticosteroid, budesonide, was able to specifically suppress the baseline numbers of bone marrow inflammatory cell progenitors, but was unable to inhibit the allergen-induced increases in these cells. In summary, the findings in this thesis suggest that inflammatory cell progenitors in the bone marrow are affected by inhalation of allergen, with increased production and trafficking to the airways. In addition, while budesonide may have an inhibitory effect on the steady state turnover of eosinophil/basophil progenitors, it has no effect on the allergen-driven events occurring in the bone marrow, suggesting that the inhibitory effects of budesonide inhalation on inflammation and airway responses may not be via inhibition of allergen-induced increases in eosinophil production.

abstract: Doctor of Philosophy (PhD)


title: Ionic stability of oxide particles in polar organic media

contributor:
Nicholson, Patrick S.
Materials Science and Engineering

abstract: The ionic stability of oxide particles in polar non-aqueous media is studied. Surface chemistry and interparticle forces are manipulated by controlling the acidity and ionic strength of the suspensions without dispersants. The acidity of ethanolic solution is determined using ion transfer functions, wherein the relationships between acidity, oxide particle-surface-charge, zeta-potential, stability and suspension rheological behaviour are established. The ionic stability of oxide particles in ethanol can be controlled by combination of potential determining ions and indifferent electrolyte to optimize the values of repulsive potential and repulsive force. It is shown oxide particles can be charge-stabilized, as in aqueous suspensions. The viscosity and flow curves for oxide/ethanol suspensions are acidity dependent. The flow curves of the suspensions follow the Casson model and the Casson yield value is used to evaluate their stability. Positive isoelectric point shifts were observed for alumina and magnesia in ethanol on increasing the solid concentration. However both dilute and concentrated aqueous suspensions of alumina give the same isoelectric point. Silica/ethanol suspensions are stable near the IEP. This result suggests the colloidal stability of silica in ethanol can not be explained exclusively by the ionic stability mechanism of DLVO theory. The discrepancy is believed due to a steric barrier consisting of a silicic acid gel network. The surface chemistry and rheological properties of alumina suspensions in EtOH and DMSO are strongly influenced by the ionic strength of the suspensions. Rheological measurements show the viscosity of the suspensions decreases with increasing salt concentration due to suppression of the second electroviscous effect. Solvent is found to have a marked influence on suspension rheology. The heterocoagulation behaviour of oxide-mixture/ethanol suspension systems is examined, elucidating the general principles underlying structure formation in mixed dispersions. It is demonstrated that the architecture of composites can be controlled by manipulation of the relative colloidal stability of the constituent primary particles.

abstract: Doctor of Philosophy (PhD)


title: Active-passive corrosion of iron-chromium-nickel alloys in hot concentrated sulphuric acid solutions

contributor:
Ives, M.B.
Materials Science and Engineering

abstract: In the manufacture of sulphuric acid more stringent environmental standards and operation economics have forced the industry to improve product utilization, energy efficiency and reliability. A key to improving both the thermal efficiency and reliability is the use and/or development of more corrosion resistance materials including stainless steels, especially in the parts of the plant that handle the condensed acid. Application of more corrosion resistant material requires a better understanding of the corrosion mechanism involved in concentrated H2 SO4 -H2 O (>90 wt.%) solutions. While corrosion kinetics of carbon steel, the traditional material of construction, are relatively well understood, this is much less true in the case of the cyclic active-passive corrosion of stainless steels. Models proposed to explain the cyclic active-passive corrosion involve a periodic formation of either a protective metal sulphate film or an insoluble sulphur layer. To better understand the reactivity and/or passivity of stainless steel in concentrated H2 SO4 -H2 O solutions a study employing immersion and electrochemical techniques, including rotating electrodes, was conducted in order to clarify the following: (1) The state of stainless steel passivity. (2) The conditions in which passivity is stable. (3) The role played by the major alloying elements in establishing and maintaining the passive state. The study involved evaluating the corrosion behaviour of stainless steels S30403 and S43000 along with iron, chromium and nickel in 93.5 wt.% H2 SO4 at temperatures between 25-80°C. Major discoveries of the study include: (1) A content of 17-18 wt.% chromium is sufficient to anodically passivate S43000 as the potential is made more noble. Passivity is not stable and requires anodic polarization. (2) Alloyed nickel plays an active role in improving the corrosion resistance of stainless steel. A content of 8 wt.% nickel is sufficient promote a periodic passivation of the base Fe-(17-18)wt.% Cr stainless steel under open-circuit conditions which reduces the corrosion rate by at least an order of magnitude. (3) The electrolysis of concentrated H2 SO4 -H 2 O solutions involves a potential-dependent reduction of H2 SO 4 molecules to sulphur-containing species with an oxidation state lower than six (6). The various reduction products have a significant effect on the stainless steel corrosion resistance. (4) Successful modelling of the corrosion of nickel has been accomplished by using a galvanic interaction between a noncontinuous nickel sulphide (NiS) deposit, formed in situ, and the uncovered nickel metal. (5) Successful modelling of the active-passive corrosion of S30403 has been accomplished using a galvanic interaction between NiS(Ni) and S43000.

abstract: Doctor of Philosophy (PhD)


title: Interactive Muon Catalyzed and Intertial Confinement Fusion

contributor:
Harms, A.A.
Nuclear Engineering

subject:
Engineering
Nuclear Engineering
Engineering

abstract: Energetic viability calculations of nuclear fusion energy systems based on two distinct approaches to a symbiotic combination of Muon Catalyzed Fusion (µcf) and Inertial Confinement Fusion (ICF) have been performed. The first approach involves a deuterium-tritium ICF pellet ignited by muon catalyzed fusion heating; the second approach is based on the energy generated by µCF reactions in deuterium-tritium compressed to high density. Viability evaluations rely upon modeling of identified critical energy gain parameters for energy systems based upon each of the µCF-ICF system and developing muon catalyzed reaction models in conditions found in high density compressions. An energy system based on µCF in compressed deuterium-tritium was found to be non-viable due primarily to the sharp decrease in the muon induced fusion rate for temperatures greater than 40 eV. The viability of a fusion energy system based on the µCF triggered spark ignition is favorable provided that technology can be developed which allows for the deposition of sufficient quantities of muons into a very small volume within a very short duration.

abstract: Doctor of Philosophy (PhD)


title: Molecular dynamics and reaction kinetics during polymerization using dielectric spectroscopy and calorimetry

contributor:
Johari, G.P.
Materials Science and Engineering

abstract: The evolution of molecular dynamics during the polymerization of linear-chain and network forming liquids was studied using dielectric spectroscopy and differential scanning calorimetry. Polymerization was carried out using step-addition reactions between epoxide and amine molecules, and by catalysis of epoxide molecules with tertiary amines. The former resulted in linear-chain or network structured polymers while the latter resulted in network polymers. The step-addition polymerizations resulted in linear-chain polymers by reacting stoichiometric quantities of diepoxide and monoamine molecules, and network structure polymers by reacting stoichiometric quantities of triepoxide and monoamine molecules, or diepoxide and diamine molecules. The growth and extinction of localized (or secondary) relaxation processes during the polymerization were studied by measuring the changing dielectric properties using two techniques; fixed frequency dielectric measurements during heating of the partially polymerized samples, and isothermal dielectric measurements over the frequency range of 1 MHz to 20 GHz. The number of covalent bonds formed at any instant during the polymerization was determined by isothermal calorimetric measurements. Thus, the change in the dielectric properties during polymerization was associated with the increase in the number of covalent bonds. It was found that the localized relaxations evolve in a manner that is independent of the spontaneous increase in configurational entropy. The results also tend evidence towards the concept that these relaxations occur in regions of relatively high energy, and the collapse of such regions led to the observed changes in the dielectric properties. As well, an analogy was made between the structural relaxation of a physically metastable glass and the polymerization of a chemically metastable liquid. This has lead to the concept of a chemical fictive temperature to describe the state of the polymerizing liquid. The effects of pressure on the dielectric properties of the polymerizing liquids was studied using fixed frequency dielectric measurements. Pressure was step-increased, both at the beginning of the polymerization and at a time during the polymerization, then maintained. An increase in pressure increased the rate of polymerization, and thus the dielectric properties evolved more rapidly with time. The chemical effects of pressure during polymerization were examined using transition state theory and the concept of negative feed-back. The physical effects of pressure were investigated in terms of its effects on the equilibrium dielectric properties. It was shown that the polymerization kinetics are increased with increased pressure when the kinetics are in the mass-controlled regime, and decreased with increased pressure when the kinetics are in the diffusion-controlled regime. The transition from mass- to diffusion-controlled kinetics was investigated using the rate of change of the dielectric loss. Finally, the chemical and physical effects of step-increased pressure upon the dielectric properties of polymerizing liquids in the mass-controlled regime were mathematically simulated using current concepts and formalisms. The simulated results were qualitatively similar to those obtained experimentally, demonstrating the adequacy of the understanding.

abstract: Doctor of Philosophy (PhD)


title: Characterization of the prostanoid TP receptor population in human nonpregnant myometrium

contributor:
Crankshaw, D.J.
Health Sciences

subject:
Medicine and Health Sciences
Medicine and Health Sciences

abstract: Since the pioneering work of Pickles et al . (1965), prostanoids have been implicated in the pain and discomfort of primary dysmenorrhea. Accordingly, current pharmacotherapy is based on the inhibition of prostanoid synthesis. However, 10% to 25% of women who suffer from primary dysmenorrhea fail to gain relief from such therapy. The development of alternative therapies to treat these women has been hindered by the fact that the effects of prostanoids on human nonpregnant myometrium have not been quantified in a rigorous way. The prostanoid thromboxane A2 , causes vascular smooth muscle contraction by interacting with specific prostanoid receptors known as TP receptors, the nomenclature follows recent International Union of Pharmacology recommendations where each prostanoid receptor is designated by the letter P, preceded by a letter signifying the most potent natural prostanoid agonist at that receptor. At the time my thesis was undertaken, several observations suggested that the TP receptor may be involved in the physiological and pathophysiological control of myometrial contractility. Therefore, the purpose of this study was to thoroughly characterize the TP receptor population in human nonpregnant myometrium. I evaluated the pharmacological characteristics of the myometrial TP receptor via in vitro functional and radioligand binding studies and employed reverse transcription-polymerase chain reaction assays to evaluate TP receptor mRNA expression. Both U-46,619 and I-BOP produced concentration-dependent contraction of human myometrial strips in vitro (p EC50 = 6.9 ± 0.27; and 7.8 ±0.60, respectively). The contractile activity induced by U-46,619 was attenuated by seven selective TP receptor antagonists. Lastly, the sensitivity of human nonpregnant myometrium was not regulated by anatomical location, tissue orientation or menstrual cycle status of the donor. The binding of [125 I]-BOP to human myometrial membranes was saturable, selective and displaceable. Equilibrium binding of [125 I]-BOP identified one class of sites, Kd = 3.4 nM (pKd = 8.7 ± 0.4) and a maximum binding of 323.1 ± 361.5 fmol/mg protein. The addition of the non-hydrolyzable GTP analog GTPγS (100 μM), to the assay had no effect on [125 I]-BOP binding. The rank order of potency for the seven TP receptor antagonists in displacing [125 I]-Bop from its binding site was correlated (r = 0.75) with the rank order of potency in inhibiting U-46,619-induced contraction of myometrial strips. Ligands selective for other prostanoid receptors were unable to significantly displace [ 125 I]-BOP binding. A novel qualitative RT-PCR methodology was developed and with this technique TP receptor mRNA expression was demonstrated in human nonpregnant myometrium excised from different uterine locations, from donors in both the proliferative and secretory phases of the menstrual cycle. The basis for a semi-quantitative RT-PCR methodology was established and an examination of potential influences on TP receptor mRNA expression, such as tissue excision site and donor menstrual cycle status, was begun. Lastly, the semi-quantitative data describing the amplification of TP receptor mRNA was highly variable, however the factor(s) responsible for such high variability remain to be determined. All taken together, these results suggest that a single homogeneous population of TP receptors, most closely resembling the putative low affinity TP receptor population in human platelets, resides in human nonpregnant myometrium.

abstract: Doctor of Philosophy (PhD)


title: Diffusion studies in InGaAs/GaAs and AlGaAs/GaAs quantum well structures

contributor:
Weatherly, G.C.
Purdy, G.
Materials Science and Engineering

abstract: This work has involved a study of diffusion and ion implantation enhanced diffusion in GaAs based semiconductor heterostructures. A knowledge of kinetic parameters underlying the diffusion process is of practical value in the fabrication of optoelectronic devices. Two main problems have been explored. (a) Thermal interdiffusion of (InGaAs/GaAs)quantum well structures and superlattices. Transmission electron microscopy, X-ray diffraction and photoluminescence experiments have been undertaken to follow the temporal evolution of the indium composition during annealing of the superlattice. A linear model of diffusion has been utilized to calculate the evolution of strain, indium composition and the X-ray diffraction intensity during annealing. Calculation of energy levels of the electrons and holes in the superlattice structure and their evolution with annealing have also been performed following a transfer matrix approach. This has been used to predict the experimentally observed trends in photoluminescence. Non linear aspects of diffusion including composition dependence and strain dependence (by growth on 311A substrates) have also been experimentally examined. (b) Ion implantation enhanced disordering of III-V compound semiconductor heterostructures (InGaAs/GaAs, GaAs/AlGaAs). Various parameters which influence the disordering process, namely the implant energy, ion species, implant temperature and heterostructure composition have been studied with transmission electron microscopy (conventional/high resolution) and photoluminescence techniques. Several interesting phenomena with respect to the position and crystallographic nature of implant damage have been observed. A phenomenological model to rationalize data has been developed by numerically solving the governing diffusion equations.

abstract: Doctor of Philosophy (PhD)


title: Damage in MMCs and its role in microstructural design

contributor:
Embury, J.D.
Materials Science and Engineering

abstract: Metal-matrix composites (MMCs) have potential as load bearing components for particular functional requirements. However, MMCs are more difficult to form than conventional metals and alloys due to the tendency of suffering microstructural damage at low plastic strains. It is thus of importance to understand the forms of microstructural damage, its level and spatial distribution. In this work, three main areas of investigation related to damage accumulation in MMCs were considered: the hydrostatic extrusion of MMCs, a theoretical investigation of scale effects in MMCs and plane strain compression experiments on model composites to study load transfer and fibre distribution effects on the patterns of plastic flow in the matrix. In the experiments on the hydrostatic extrusion of particulate MMCs, it was found that damage occurred in the form of reinforcement cracking, that the amount of damage varied linearly with applied plastic strain and that the rate of damage accumulation depended on the morphology of the reinforcement. The extrusion process was examined in regard to its ability to limit or suppress damage through the action of high compressive hydrostatic pressures. A slip-line field analysis was adopted to relate the effect of process parameters such as the amount of reduction and die angle to the magnitude and distribution of hydrostatic pressure in the extrusion dies. The linear relationship between damage and applied plastic strain was explained using a micro-mechanical description of the response of MMCs to plastic flow and the effect of microstructural variables such as volume fraction, shape and size of the reinforcement on the rate of damage accumulation was discussed. In addition, the tensile properties of MMCs subsequent to hydrostatic extrusion were quantified and the effect of previous extrusion was described in terms of the strain hardening of the matrix materials and the damage accumulation in the reinforcement materials and their influence on the stability of the plastic flow process. In the work on plane strain compression of model composites, the effect of reinforcement distribution on the pattern of flow in Cu-W MMCs was described using maps of equivalent strain obtained from the analysis of deformed surface grids. The level and distribution of strain was found to be related to the spatial distribution of the reinforcements. The fiber distribution also influenced the efficiency of the fibers as obstacles to macroscopic flow. Comparison of the results with numerical analyses allowed a link to be established between the observed damage mechanism of decohesion and the state of stress and local strain level in the composite. An optical method was used to get information on the load transfer process in a Cu-sapphire MMC plastically deformed in plane strain compression. The fracture of the sapphire fiber was related to the measured stress state. In the theoretical analysis of scale effects in MMCs, scale dependent bounds on strength were developed and scale dependent composite design charts were constructed. The results highlighted the importance of the scale of the reinforcement in MMC design, as well as the importance of the processing route to fabricate MMCs on a fine scale. The conclusions of the various areas of investigation demonstrated how damage in MMCs links together issues of process design, microstructural optimization and resultant mechanical properties of MMCs.

abstract: Doctor of Philosophy (PhD)


title: High-resolution analytical electron microscopy and creep deformation of silicon nitride ceramics

contributor:
Wilkinson, D.S.
Weatherly, G.C.
Materials Science and Engineering

abstract: The typical microstructure of silicon nitride consists of rigid Si3 N4 grains and intergranular amorphous films associated with the liquid phase sintering process involved during densification. The presence of the amorphous films may affect the creep behaviour of silicon nitride ceramics at elevated temperatures. The advent of high resolution transmission electron microscopy (HRTEM) coupled with fine-probe chemistry analysis enables us to investigate the structure and chemical composition of the nano-scale grain boundary amorphous films and the role they play in creep deformation of silicon nitride. The materials investigated consist of β-Si3 N4 grains with and without secondary crystalline phases. All grains were covered with a thin intergranular amorphous film at both homophase and heterophase boundaries. It was found that these amorphous films have a characteristic value of thickness, independent of grain misorientation, but dependent on the chemical composition of the film and the grains on either side of the film. The creep behaviour of the materials were evaluated by compressive and tensile testing. The grain-boundary film thickness distribution was measured before and after creep using both high-resolution lattice imaging technique and Fresnel fringe imaging technique. The results show a narrow range of film widths in the uncrept material but a bimodal distribution after creep. This provides, for the first time, direct evidence for the occurrence of viscous flow of intergranular amorphous films during creep deformation of silicon nitride. Finally, a model is developed to describe the viscous flow process in multi-phase Si3 N4 materials in contrast to prior models which are only applicable to "pure" Si3 N 4 materials. The creep response predicted by the model is consistent with the experiment.

abstract: Doctor of Philosophy (PhD)


title: The role of galvanic coupling effect in determining crevice corrosion morphology

contributor:
Ives, M.B.
Materials Science

subject:
materials science
Materials Science and Engineering
Materials Science and Engineering

abstract: The galvanic nature of crevice corrosion is a generally accepted concept but the coupled electrochemical behaviour and its role in crevice corrosion has not been really studied until recently. Among many arguments regarding the mechanism of crevice corrosion, whether or not being able to reasonably interpret the shape of crevice attack is an indication of whether or not the physical processes involved in crevice are profoundly understood. Based on a critical review of the state-of-the-art of the crevice corrosion studies, the necessity of studying the role of galvanic coupling effectiveness in crevice corrosion is then proposed. The concept of a uniform anode/cathodic pair with IR-drop is developed. It is shown that the galvanic coupling effect may play a significant role in crevice corrosion. For a uniform anode/cathode pair with IR-drop, the coupled potential/current relationship is a function of the kinetics on both the anode and cathode. It is found that when the anodic environmental aggressiveness exceeds certain value, the whole process is shifted from anode control to cathodic control and, therefore, the anodic dissolution rate is significantly enhanced. What complicates the process is the inevitably existing IR-drop which increases while the anodic-to-cathodic control shift occurs. This increased IR-drop is the consequence of the increase in anodic dissolution and on the other hand impedes the further increase in anodic dissolution. Therefore, the current/potential relationship in this case is being treated in a "covariant" way. In order to define the degree of the enhancement in anodic dissolution due to the coupling effect, a dimensionless parameter, the coupling coefficient η, is proposed, which is a function of anodic solution aggressiveness as well. A real corroding crevice is considered as an array of the uniform anode/cathode pair with different solution ohmic resistance. The concept of coupling effectiveness and the procedure of obtaining coupled dissolution rate as a function of solution aggressiveness and ohmic resistance of the solution phase are applied to a real corroding crevice, attempting to explain the shape of crevice attack and its evolution. Micro-electrodes techniques for measuring solution aggressiveness inside a real corroding crevice and a proper method for calculating the coupled dissolution rate at any location inside the crevice are developed. By (i) determining the local solution aggressiveness at different locations inside a corroding crevice, (ii) obtaining the kinetic information for the interior anodes in corresponding environments, and (iii) calculating the coupled dissolution rates at these locations, we are able to obtain the distribution and evolution of the coupled dissolution rate and the coupling effectiveness along the crevice. The shape of the crevice attack and its evolution with time is then attempted by integrating the coupled dissolution rate over the total time elapsed. The results show reasonably good agreement between the calculated shape of attack and its evolution and the experimental result. An alternative criterion for crevice corrosion of materials is proposed based on the response of the material to coupling effect.

abstract: Doctor of Philosophy (PhD)


title: Novel cysteinyl leukotriene biology in human airways

contributor:
O`Byrne, P.M.
Physiology and Pharmacology

subject: physiology and pharmacology

abstract: Cysteinyl leukotrienes (LTC4 , D4 , E4 ) play an important role in the pathophysiology of asthma. They produce bronchoconstriction, microvascular leakage and eosinophil infiltration into the airway mucosa. They mediate the airway responses following allergen inhalation and exercise. This thesis examined new effects of cysteinyl leukotrienes on three cells in human airways: an antigen presenting cell (dendritic cell), a key inflammatory cell (eosinophil) and a structural cell (smooth muscle). Dendritic cells initiate allergen-induced airway responses by presenting the allergen to lymphocytes. Cysteinyl leukotrienes are necessary for the migration of dendritic cells from tissues to the regional lymph nodes. We observed that they also regulate the recruitment of myeloid dendritic cells from peripheral blood following an allergen inhalation. In a clinical trial, we observed that two weeks of treatment with a leukotriene receptor antagonist prevented the allergen-induced decrease in the number of circulating myeloid, but not plasmacytoid, dendritic cells in atopic asthmatic subjects. This was in keeping with our observation that greater proportion of myeloid dendritic cells than plasmacytoid dendritic cells expressed the CysLT1 receptor. Esoinophilic infiltration of the airway is a characteristic feature of asthma pathology. We observed that inhalation of cysteinyl leukotrienes caused an increase in the number of eosinophils in airway mucosa and lumen in subjects with atopic asthma. We also observed that leukotriene E4 caused greater eosinophilia than leukotriene D4 . We further examined bone marrow eosinophilopoiesis as one of the mechanisms by which leukotrienes cause airway eosinophilia. Treatment of atopic asthmatic subjects with a leukotriene-receptor antagonist for two weeks attenuated allergen-induced increase in the number of eosinophl/basophil colony forming units in the bone marrow. This was the first in-vivo observation of a direct role of cysteinyl leukotrienes in regulating eosinophilopoiesis in humans. The first recognized biological effect of cysteinyl leukotrienes was their ability to contract smooth muscles. We observed that they could also modulate another property of human airway smooth muscle, i.e., migration. We observed that human airway smooth muscle cells show chemotaxis towards platelet-derived growth factor. Although leukotrienes by themselves were not chemoattractants, they caused chemokinesis of smooth muscle cells and augmented chemotaxis towards platelet-derived growth factor. A leukotriene receptor antagonist inhibited this. The mechanism was not dependent on increased integrin expression on smooth muscle, or Src-kinase or phosphatidylinositol 3-kinase phosphorylation. (Abstract shortened by UMI.)

abstract: Doctor of Philosophy (PhD)


title: The Effects of Coupled Translational - Torsional Dynamic Response on Buildings

contributor:
Tso, W.K.
Civil Engineering

subject:
Civil Engineering
Civil Engineering

abstract:
An investigation is made into the coupled lateral - torsional response on frame buildings to horizontally directed earthquake excitation. Attention is confined to the accuracy of the static code provision on torsional effect with special reference to the National Building Code of Canada 1977 (NBC 77).

A mathematical model to compute the dynamic response of a building is presented. The formulation of the general equation of motion to a monosymmetrical building is developed in detail. The static storey torque is compared with the dynamic torque computed by using the response spectrum technique as outlined in the Commentary K of NBC 77. It has been found that the sympathetic coupled translational torsional resonance occurs at the buildings with small eccentricities. To uniform structure, the static code torque estimate is good if the effect of sympathetic coupled resonance is not significant. To building with large eccentricities, sympathetic resonance is unlikely to occur and the current NBC requirement of doubling the computed torque for design is a very conservative requirement.

To buildings with eccentrical offset, NBC 80 proposes a modification on the definition of structural eccentricity. A study in this aspect is made through the floor torques comparison between dynamic analysis and static codes calculations. The results show that the improvement by NBC 80 is only partial. Buildings with eccentric offsets are irregular buildings, only a dynamic approach can lead to a realistic estimate of the torque distributions.

abstract: Master of Engineering (ME)


title: Rādhā: The Parodhā Nāyikā

contributor:
Kinsley, David
Granoff, Phyllis
Younger, Paul
Religious Studies

subject: Religion Religion

abstract:
This thesis is a study of the adultery theme in the major texts of Bengali Vaisnavism. Using a chronological approach to the literature a study was made of how the adultery, or parakiya, theme was used in various texts throughout this tradition. This was facilitated by focusing on the figure of Rādhā who was considered the favored consort of the cowherd god Krsna.

The literature involved is categorized into works which are considered narrative or poetic in character, and texts which are explicitly theological or apologetic. In the former group of literature is included the earliest devotional poetry of the Bengali tradition: the Gītagovinda of Jayadeva (12th century), the padavali of Vidyāpati (14th century), and the padas of Candīdās (14th century). Also included are the Dānakelikaumudī of Rūpa Gosvāmin (16th century) and the Brahmavaivarta Purāna (16th century).

What was implicit in the devotional literature mentioned above was made explicit by the Gosvāmins of Vrndāvana. The theological perspectives of Rūpa and Jīva Gosvāmin on the parakīyā issue vary from the earlier literary tradition, (see Chapt. II, sec. 2). The Tantric Sahajiya cult offered an interpretation of Rādhā's adultery in line with the Sahaja practice of taking a woman in sādhanā, (Chapt. II, sec. 3).

In the conclusion questions are raised concerning the appeal of the adultery theme in devotional literature. Offered are parallel examples of adultery in the literature of other religious traditions and an analysis of this theme in reference to love in separation. This may offer explanations as to how such a theme persisted in the literature of Bengali literature.

abstract: Master of Arts (MA)


title: The Design of a System for the Evaluation of Comprehensive Primary Health Care in Rural Sierra Leone

contributor: Design, Measurement and Evaluation: Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
The purpose of this thesis is to describe a research design for evaluating the effectiveness of comprehensive primary health care in rural areas of Sierra Leone.

Comprehensive primary health care, which is based on community participation within the framework of a policy of self-reliance and self-development is seen by many as the answer to solving the health problems of deveIoping countries.

In setting the scene for evaluating the effectiveness of comprehensive primary health care in rural Sierra Leone, a description of the background of the country is given highlighting the major geographical, demographical and socioeconomical features. The state of health in the developing countries as a whole is also reviewed (Chapter 3).

Chapter 4 explores the concept of comprehensive primary health care and reviews the operational aspects in the African context.

In an attempt to establish some basis for the design of an effectiveness evaluation of comprehensive primary health care, the main methodologic issues in the presented setting are explored (Chapter 5).

Having identified the main methodologic issues specific solutions and their justifications are proposed (Chapters 6,8,9).

Finally, a specific protocol of the proposed research design is presented.

abstract: Master of Science (MS)


title: Information system capabilities and emergent competitive strategies: An investigation of the strategic fit of supply chain management information systems

contributor:
Head, Milena M.
Yuan, Yufei
Management Science/Information Systems

subject: management science/information systems

abstract: This study develops a model for analyzing fit between a firm's competitive strategies and the capabilities of their Supply Chain Management Information Systems (SCM IS). Concepts such as configurational theory, the resource based view of the firm, and emergent strategies and capabilites--all of which are underutilized in current IS literature--ground the study theoretically. A positivist case study of five manufacturers is used to explore the constructs and identify appropriate measures for operationalizing the model. The developed model enables IS planners to quickly analyze their firm's competitive strategy patterns and determine the ideal level of support required for each SCM IS capability. Firms can improve the effectiveness of their IS and reduce the risk and cost of misfits, by implementing information systems that fit their emergent competitive strategies. The developed model is a significant improvement over traditional models that advocate aligning information systems with a firm's intended strategies or their current functional requirements, both of which change more frequently than a firm's emergent competitive strategy patterns. The case study investigations yielded several important findings. First, Miles and Snow's (1978) competitive strategy typology proved useful for classifying a firm's emergent competitive strategy patterns and reducing the complexity of analysis. However, the qualitative evidence more strongly supported the use of Conant et al .'s (1990) multi-dimensional questionnaire measure of competitive strategy type rather than Miles and Snow's (1978) paragraph measure. Second, existing conceptualizations of IS capabilities were not well suited to analyzing SCM IS specifically. The findings support the conceptualization of SCM IS capabilities as the level of support provided for: operational efficiency, operational flexibility, planning, internal analysis, and external analysis. Finally, the empirical results strongly supported modeling the strategic fit of a firm's SCM IS as the amount the perceived level of support provided for each SCM IS capability was less than the theoretically ideal level, rather than the more common approach of modeling strategic fit as the absolute deviation between perceived and theoretically ideal levels.

abstract: Doctor of Philosophy (PhD)


title: Modelling a Foundation of Grade 4 by the Finite Element Method

contributor: Civil Engineering and Engineering Mechanics

subject:
Civil Engineering
Engineering Mechanics
Civil Engineering

abstract:
In any given health care system where the incidence of disease is high and the outcome poor, the process of care should be examined to determine changes that can be made, which will lead to improved outcome. The hypothesis to be tested in this study is that carefully designed and administered continuing education programme for nurses will improve the process of care and improve the outcome in critically ill children who have been hospitalized because of measles, meningitis or tetanus. In other words, improved nursing education improve's quality of care. This thesis presents a randomized controlled trial to test the hypotheses.

Issues in quality of care and quality assurance are discussed. An in-service education programme is developed for nurses who have no pediatric special case training but, because of shortage of medical personnel, are depended upon heavily to make judgements about care of critically ill infants.

This educational programme is based on pathophysiological states which are designated indicator based on pathophysiological conditions. The quality of care studies done before and after the educational programme are based on nurses' management of infants with these indicator conditions. The use of pathophysiological states rather than specific diseases allows for a greater number of pediatric patients to be managed by nurses who have this in-service training since most of the infants admitted into the hospitals develop one or any combinations of these morbid states.

A general hospital setting is chosen for this study for greater generalizability of the results since most of these infants are cared for in general hospitals; only a negligible number compared to the high incidence are admitted into teaching hospitals.

To reiterate: the main questions that this thesis seeks to answer are:

1. Did the nurses learn?

2. Did they change their practice behaviour?

3. If (1) and (2) had occurred, did the patients' health outcome change?

abstract: Master of Engineering (ME)


title: The uncoupling of the inflammatory and structural components of airway hyperresponsiveness

contributor:
O`Byrne, P.M.
Cox, G.
Gauldie, J.
Physiology and Pharmacology

subject: physiology and pharmacology

abstract: Airway hyperresponsiveness (AHR) is a characteristic feature of asthma. However, the mechanisms underlying AHR are complex and likely to be multi-factorial. A number of animal models have focused on understanding the mechanisms of transient airway inflammation and the associated transient airway dysfunction that occur following brief allergen exposure. While much has been learned about the role of acute inflammation in this brief allergen-induced response, a limitation of these studies is that the airway dysfunction is not fully representative of the AHR present in asthma. For example, we have shown that effective anti-inflammatory treatment results in only a modest reduction in AHR, indicating that AHR is usually sustained in asthma. This suggests that other mechanisms, including airway remodeling, likely play an important role in the pathophysiology of AHR. The subsequent focus of this thesis has been firstly, to demonstrate that sustained airway dysfunction develops in mice chronically exposed to allergen, and secondly, to explore the potential mechanisms and associations underlying this phenomenon. By subjecting sensitized mice to either brief or chronic periods of allergen exposure, we have developed a novel model in which chronic allergen exposure results in sustained airway dysfunction and structural changes of the airway. Subsequently, mice deficient for IL-4, IL-5 or IL-13 were studied using similar protocols. IL-4 and IL-13, but not IL-5, are critical for the development of airway remodeling, and in the absence of remodeling, mice were protected from developing sustained airway dysfunction. In further experiments, mice were either T cell immuno-depleted using monoclonal antibodies, or were treated with an anti-IL-13 fusion protein. When these interventions were given after chronic allergen exposure, at a time when airway remodeling was established, neither intervention attenuated the sustained airway dysfunction. Taken together, these results provide new information about basic physiological mechanisms underlying the sustained airway dysfunction present in asthma.

abstract: Doctor of Philosophy (PhD)


title: Bridging the gap: Promoting physical activity among individuals with spinal cord injury within the context of the theory of planned behaviour

contributor:
Martin, Kathleen A.
Human Biodynamics

subject: human biodynamics

abstract: The purpose of this dissertation was to develop an understanding of physical activity behaviour and to promote physical activity participation among individuals with spinal cord injury (SCI) within the context of the theory of planned behaviour (Ajzen, 1985). Using a "bottom-up," programmatic research approach, this three-study thesis involved (1) validating a new measure of physical activity that is appropriate for use among individuals with SCI, (2) identifying theoretically meaningful, psychosocial predictors of physical activity participation in the SCI population, and (3) implementing and testing a theory-based intervention focused on helping people with SCI follow through with their physical activity intentions. Specifically, Study 1 examined the construct validity of the Physical Activity Recall Assessment for Individuals with SCI (PARA-SCI). An assessment of convergent validity (n = 73) and construct validation by extreme groups (n = 158) provided evidence of the construct validity of the leisure time physical activity (LTPA) PARA-SCI category but not the lifestyle or cumulative activity PARA-SCI categories. It was concluded that the PARA-SCI is suitable for assessing LTPA among individuals with SCI and should be used to advance research examining physical activity determinants. Using the LTPA PARA-SCI category as a primary outcome, the purpose of Study 2 was to examine determinants of physical activity among people with SCI (n = 110) within the context of the theory of planned behaviour (Ajzen, 1985). This prospective study revealed that attitudes, subjective norms and perceived behavioural control (PBC) predicted physical activity intentions while intentions, but not PBC, explained a small amount of the variance in LTPA. The poor prediction of behaviour suggested a need to investigate whether strategies that facilitate the translation of intentions into behaviour can serve to strengthen the intention-behaviour relationship. Study 3 utilized a randomized, controlled design to examine the efficacy of an 8-week implementation intention intervention as a means of helping individuals with SCI (n = 53) follow through with their intentions for physically active living. The results indicated that participants who formulated implementation intentions (i.e., the implementation intention condition) spent more time engaged in physical activity and were more likely to enact their intentions than individuals who did not create implementation intentions (i.e., the control condition). Further, participants in the implementation intentions condition had stronger intentions and greater confidence to schedule their physical activity than participants in the control condition, suggesting that implementation intentions may influence cognitions related to physical activity. (Abstract shortened by UMI.)

abstract: Doctor of Philosophy (PhD)


title: The Wilderness Motif in Jeremiah: A Rhetorical Analysis

contributor:
Hobbs, T. R.
Religious Studies

subject: Religion Religion

abstract:
This thesis re-examines Jeremiah's use and understanding of the wilderness motif. The first chapter reviews and critiques the secondary literature on the subject. Since the two major passages referred to in support of the "nomadic ideal" are Hos. 2:16-17 and Jer. 2:2-3, their past interpretations receive special attention.

Chapter two is a rhetorical and contextual analysis of Jer. 2:2-4:4. Based on a series of contrasts discovered in this passage, it is concluded that Jeremiah does refer to the wilderness period as a time when Israel responded to Yahweh in a positive manner. It is also suggested that the bases of Jer. 2:2-4:4 is Israel's breach of the Mosaic covenant, and Yahweh's desire to establish a new covenant.

Chapter three examines the history of the marriage metaphor as a means of illustrating Yahweh's relationship with Israel. It is concluded that there are two sources of the metaphor. The first originates with the incident at Beth Baal Peor. There Israel participated in sexual intercourse as a means of worshipping Baal Peor, and this event was interpreted and described as religious harlotry. Both Hosea and Jer. 2:2-4:4 reflect this tradition. The second is grounded in the old Canaanite idea that capital cities were royal goddesses. This concept was adopted by the Judeans after David's conquest of Jerusalem, and is visible in the writings of the southern prophets, Isaiah, Micah, and Ezekiel.

abstract: Master of Arts (MA)


title: Enzymatic Modification of Peptides in the Brain

contributor:
Chan, W.W.-C.
Biochemistry

subject: Biochemistry Biochemistry

abstract:
Certain post-translational modifications of peptides in the brain were studied in order to answer three questions. (1) Does an enzyme exist in the brain with properties similar to glutamine cyclotransferase of papaya latex? (2) Does formation of carboxyamide residues only require the presence of a carboxyl terminal glycine in the respective precursor? (3) Does a nonspecific ligase exist in the brain? Experiments are described that attempted to answer these questions. Amino terminal glutaminyl peptides were used to assay for glutamine cyclotransferase in brain homogenates. Cyclization of the amino terminal glutamine would enable these peptides to pass through a cation exchange column. Glutamic acid would be released from the product after acid hydrolysis of the eluate and determined by an enzyme assay. Isotopically labelled carboxyl, terminal glycyl peptides were synthesized and used to assay for an enzyme that exchanges glycine for ammonia. The product was separated from the substrates with an anion exchange column. A random mixture of peptides was used to assay for a nonspecific ligase. One group was [³H]-acetylated to block the amino terminals. A second group was coupled to glycinamide to block the carboxyl terminals: Coupling would alter the ion exchange properties of these substrates.

No evidence was obtained for the existence of the postulated enzymes. These results are discussed in relation to a novel hypothesis implicating peptides with memory.

abstract: Master of Science (MS)


title: The role of bone marrow inflammatory cell progenitors in allergen-induced asthma

subject: physiology and pharmacology

abstract: Asthma is a chronic airways disease characterised by recurrent episodes of wheezing and variable airflow obstruction, which is usually reversible spontaneously or with treatment, and with airway hyperresponsiveness, and airway inflammation. Allergen inhalation by sensitized, atopic asthmatics enhances airway hyperresponsiveness and inflammation, providing a useful model to study allergic asthma. The aim of this thesis was to characterise the allergen-induced changes in bone marrow eosinophil/basophil (Eo/B) progenitors, their ability to migrate out of the bone marrow and to determine whether these cells accumulate in the airways to participate in the allergen-induced airway inflammatory response. In addition, this thesis attempted to investigate the importance of pro- and anti-inflammatory cytokines and chemokines which contribute to the migration and differentiation of these cells. Bone marrow aspirates, blood and sputum samples were obtained from subjects at various time points both before and following allergen inhalation challenge. In comparison to isolated early responders, who develop no allergen-induced late asthmatic responses or airway hyperresponsiveness, bone marrow Eo/B progenitor numbers were increased in dual responders, who develop marked allergen-induced airway eosinophilia and airway hyperresponsiveness. Increases in IL-3-responsive progenitors were detected as early as 5 hours post-allergen, and IL-5-responsive progenitors at 12 and 24 hours post-allergen in dual responders only. Bone marrow, blood and sputum IL-5 protein levels increased at 12 and 24 hours in dual responders only and these increases correlated with increases in IL-5-responsive progenitors. Additionally, bone marrow IFN-γ levels increased in dual responders at 48 hours coinciding with decreases in bone marrow EoB progenitors. Expression of the receptor for eotaxin (CCR3) was detected on primitive (CD34 immunopositive cells) and eosinophil-lineage committed progenitors (CD34 + IL-5Rα+ cells) by flow cytometry and confirmed by co-localization of CCR3 messenger RNA to CD34+ cells using in-situ hybridization. When pre-allergen was compared to 24 hours post-allergen levels, significant increases in bone marrow CD34+ CCR3 + cells were detected in dual responders, who also developed a significant sputum and blood eosinophilia and increased methacholine airway responsiveness. In contrast, a significant attenuation of bone marrow CD34+ CCR3 + cells was observed in isolated early responders. In a dose dependent fashion eotaxin, but not IL-5, stimulated CD34+ progenitor cell migration in vitro . (Abstract shortened by UMI.)

abstract: Doctor of Philosophy (PhD)


title: Fibrous Minerals in the Wabush Iron Ore District, Labrador, Newfoundland Canada

contributor:
Kramer, James R.
Grundy, Douglas H.
Geology

subject: Geology Geology

abstract: Fibrous minerals are common in the highgrade, metamorphic, Precambrian Wabush Iron Formation, Labrador, Newfoundland, Canada. The most abundant fibres are amphiboles of the cummingtonite-grunerite series; mineralogical studies support the work of Klein (1960, 1964, 1966) and Chakraborty (1966). Iron ore mining and pelleting operations in the Labrador City are yield tailings containing many fibres (amphibole; iron and iron-manganese compounds) which find their way into the natural waterways. Water samples in Wabush Lake have fibre concentrations greater than 2 x 10⁹ per litre. Analysis of concentration and/or chemical composition of water, tailings, rock, bottom sediment, and soil samples identifies mine waste deposits as the major source of fibres. Comparisons between sediment inputs (and inputs of mineral fibres) from mining operations and natural weathering processes indicate the major impact of mine wastes. Calculations applying Stokes' Law of Settling to the fibrous minerals illustrate how the fibres settle out in Wabush Lake.

abstract: Master of Science (MS)


title: Shop scheduling in manufacturing systems: Algorithms and complexity

contributor:
Steiner, George
Management Science/Information Systems

subject: management science/systems

abstract: This thesis describes efficient algorithms and complexity results for some machine scheduling and related problems, which are encountered in automated manufacturing systems. We introduce a new class of robotic-cell scheduling models. The novel aspect is that parts need to reenter machines several times before they are finished. The problem is to find the sequence of robot move cycles and the part processing sequence that jointly minimize the cycle time or the makespan. We show that the problems are computationally intractable with three machines and present polynomial solutions for a variety of two-machine configurations. We then consider the problem of scheduling multi-component parts in a two-machine robotic cell, where each part is composed of K identical components to be processed together on the first machine, then processed on the second machine individually. We study the cycle time and makespan minimization problems, and show that both are polynomially solvable. We investigate the problem of minimizing cycle time in a two-machine job shop, where each job has at most three operations. We reduce the problem to a two-machine reentrant flow shop problem. By extending previous results on the reentrant flow shop problem, we propose a new pseudo-polynomial algorithm, as well as a fully polynomial-time approximation scheme for certain special cases of the job shop problem. We also describe a 4/3-approximation algorithm for the general problem, and identify several well-solvable cases. Finally, we study special cases of the traveling salesman problem on permuted Monge matrices, which arose from robotic-cell scheduling problems. By using the theory of subtour patching, we reduce the problems to finding a minimum-b -weight spanning tree in the patching graph. In general, this problem is [Special characters omitted.] -hard. We show, however, that newly defined special properties of the distance matrix allow us to find in polynomial time a minimum-b -weight spanning tree, and thus an optimal tour, for these new classes.

abstract: Doctor of Philosophy (PhD)


title: A Design for a Randomized Controlled Trial to Assess the Effect of Clinical Audits on Ambulatory Care in Hospital Clinics

contributor:
Tugwell, Peter
Medicine

subject:
Medical Sciences
Medical Sciences

abstract:
A design is presented for a randomized controlled trial to answer the question: do audit procedures which hospitals are expected to carry out to meet requirements for hospital accreditation have a beneficial impact on ambulatory patient care in general and special clinics?

Approximately 60 Ontario hospitals reporting general and special ambulatory care clinics to Statistics Canada will be invited to participate in the trial. Outpatient visits to potentially eligible clinics will be documented by hospital medical records staff and submitted to the Hospital Medical Records Institute. Nurse abstractors will identify indicator conditions from this outpatient census and categorically score patient management over three periods of time: a pre-audit period before intervention occurs, a first audit period and a second audit period.

Hospitals stratified according to size and function will have been randomly allocated to three groups. Indicator conditions relevant to caseloads and casemix will be assigned to eligible clinics.

Groups I and II will both have indicator conditions introduced to clinic staff prior to the first audit period. Only Group I will receive feedback about their performance in the first audit period.

After the second audit period it should be possible to separate the effects of audit awareness (Groups I and II), of feedback (Group I) and of extraneous factors (Group III) on patient management. Results will be expressed as mean clinic scores.

If improved performances occur in Groups I and II, the usefulness of current accreditation criteria will have been demonstrated. If no change in performance occurs and the indicator condition criteria approach is accepted as being valid in this setting, then it may be appropriate to consider new approaches to accreditation.

abstract: Master of Science (MS)


title: An investigation into the mechanisms responsible for the successful completion of a ballistic elbow extension task

contributor:
Dowling, James J.
Biomechanics

subject:
Biomechanics
Biomechanics and biotransport
Biomechanics and biotransport

abstract: A dynamic ballistic elbow extension task was chosen to investigate the mechanisms responsible for achieving a high final velocity during this type of movement. After a screening process of one hundred male participants, thirty-two were chosen to be further investigated who fell into the extremes of the strength and speed continuums. The main investigation involved having participants ballistically extend their elbows against external relative loads of 0%, 20%, 40%, 60% and 80% of their maximum isometric force and two absolute loads of 1.1 kg and 2.2 kg. External torque and angular displacement measurements were recorded as well as triceps and biceps electrical activity. EMG modeling, which employed the characteristics of muscle mechanics, was used to determine the differences in performance. Isometric strength did not produce a 1:1 mapping with maximum velocity. Individuals existed that were relatively strong but not fast. Additionally, there were subjects that were quite strong but not appreciably fast. Peak instantaneous power, however, produced the best correlations with peak final velocity. To determine why certain individuals were capable of producing more power, each subject's triceps EMG was modeled in order to predict the actual muscle torque. The model predicted torques with a mean correlation of 0.957 and a mean RMSerror value of 5.8 Nm for the 224 trials. As a result of the good predictions, a forward-dynamics approach was used to manipulate weaknesses in one performance with another individual's superior attributes. Performance improvements were noted as a result. These findings demonstrate that peak instantaneous power best predicts peak terminal velocity. Furthermore, this study has developed a model capable of identifying neuro-muscular weaknesses in performance and suggesting how improvements in those areas would change the maximum velocity attained. The next stage is to determine the proper training stimuli that would make these specific neuro-muscular improvements possible.

abstract: Doctor of Philosophy (PhD)


title: Manual Motor Functions in Developmental Dysphasia

contributor: Medical Sciences (Growth and Development)

subject:
Medical Sciences
Medical Sciences

abstract:
The term developmental dysphasia refers to children who fail to develop speech and language at the normal time and in the normal manner although they do not have a primary emotional disturbance nor a physical handicap, and are not globally mentally retarded or deaf. Empirical investigations of the disorder have studied auditory perception, visual perception, linguistic and articulatory function, attention and orientation, scholastic performance and reading ability, and hemispheric specialization. With the exception of the studies of auditory perception and hemispheric specialization little promising data have been generated. Investigators of auditory perception have suggested that the language disorder in developmental dysphasia may be attributable to an impairment in auditory perceptual processing. Data from studies of the hemispheric specialization of development dysphasics suggest that dysphasics may have aberrant hemispheric specialization.

Neuropsychological investigations of adult language disturbance, i.e. adult aphasia, have concluded that the left hemisphere is specialized for certain kinds of motor function, speech and language being one such function, and that it is an impairment in certain kinds of motor function which is crucial to speech and language disturbances, and not an impairment in linguistic processing or symbolic function as has been suggested by many researchers.

This research studied developmental dysphasia with the hypothesis that since this disorder involves speech and language difficulties perhaps it might be related to a deficit in certain aspects of motor functioning, specifically, the organization and execution of fine (as contrasted with gross) actions. This motor performance was also considered within the context of hemispheric specialization since: i) previous work has indicated atypical patterns of hemispheric specialization in developmental dysphasics, ii) motor functions appear to he lateralized and iii) the motor tasks lend themselves to being performed by each hand separately.

Ten developmental dysphasics were selected according to strict criteria and were administered seven measures of motor ability, several of these being nonstandardized tests designed specifically for this research. Five of these were lateralized tests (i.e., it was required that the task be performed by each hand separately), while the remaining two were nonlateralized measures. The lateralized measures were a repetitive tapping task, the Annett peg moving task, a children's sequence box task, a hand posture imitation task and a hand movement imitation task. The Illinois Test of Psycholinguistic Abilities manual expression test and an oral movement imitation task were the non-lateralized measures. It was found that the dysphasics performed more poorly than their matched control subjects on the hand posture imitation task, the hand movement imitation task and the ITPA manual expression test. On the repetitive tapping, Annett peg moving, children's sequence box and oral movement imitation tasks the dysphasics performed as well as their control subjects: A laterality effect was not observed on any of these measures for either the normal subjects or the dysphasics.

These results were interpreted to mean that developmental dysphasics have a deficit in certain aspects of manual motor function. It is proposed that this is a specific and higher order deficit, not observed in all types of motor function. Moreover, it is suggested that it is a deficit in the initiation, organization and execution of motor behavior and not in the perception. Given that a laterality effect was not observed for any of the measures, no definitive conclusions were possible regarding the hemispheric specialization of developmental dysphasics.

Data from linguistic measures administered in addition to those used for subject selection, further confirmed the receptive language deficit in the developmental dysphasics and also indicated difficuIties in the processing of written language. These latter data were interpreted to mean that developmental dysphasia may represent a language disorder which encompasses all forms of language behavior, not just oral language reception and production.

abstract: Master of Science (MS)


title: Tensile creep of silicon carbide whisker-reinforced alumina composites

contributor:
Wilkinson, D.S.
Materials Science and Engineering

abstract: Alumina composites with 10, 20 and 30 volume % SiC whiskers were fabricated using colloidal processing methods followed by uniaxial hot pressing. The tensile creep properties of these materials have been studied between 1200°C and 1400°C. The composite slurries showed the best stability at pH = 2, which led to uniform distribution of whiskers in the final products. However, at pH ≥ 6 flocculation occurred between whiskers, resulting in whisker agglomerates in the matrix. Distribution of whiskers was characterised using neutron diffraction methods, which indicated that the whisker orientation could not be altered significantly by adjusting pH. All the composites showed much superior tensile creep resistance compared to pure alumina and the effect of increasing whisker volume fraction was significant up to 30%. Relatively high stress exponents were found, which is most probably associated with much enhanced cavitational creep in tension. The activation energy varied with whisker volume fraction, temperature and applied stress in a complex manner. This combined with the temperature-dependent stress exponents makes the identification of creep mechanisms difficult. Nevertheless, it appears that at moderate stress level grain boundary diffusion and grain boundary sliding (GBS) become more significant as whisker volume fraction increases. The composites containing 20 and 30% whiskers showed significant anelastic strain recovery (∼0.001) following tensile creep, which is consistent with earlier reports that involved bending creep tests. The whisker bending effect was studied by measuring the peak width of (111) SiC planes (perpendicular to the whisker axis) at various conditions. The difference in the peak width at room temperature was found to be insignificant before and after creep. Moreover, during in-situ neutron diffraction measurement at 1400°C, no measurable variation in the peak width was recorded from the crept samples that were cooled under load. It may be that the neutron diffraction technique used in this study is not sufficiently sensitive to measure the small bending strains developed. However, These results along with other evidence in the literature suggest that Herztian contact deformation of networked whiskers, rather than bending deformation of whiskers, may be the dominant mechanism to explain the observed anelastic strain recovery. This mechanism predicts similar strain recovery in any composite that contains constrained 'hard' inclusions with sufficient contact numbers. Models based on this mechanism have been developed, which seem to predict the magnitude of the recoverable strain reasonably well.

abstract: Doctor of Philosophy (PhD)


title: The social geography of childhood mortality in Toronto, Ontario, 1901: Patterns and determinants

contributor:
Harris, Richard
School of Geography and Geology

subject: Geography Geology Geography

abstract: This thesis investigates the patterns and causes of childhood mortality in turn of the twentieth century Ontario and Toronto, Canada. There is growing emphasis in the historical demography and geography literature on the trends and spatial variations, as well as the determinants, of childhood mortality (deaths of children under the age of five). However, our understanding of these issues, and in particular the patterns and determinants within specific places, is limited by restrictions on the accessibility of individual-level data. This research focuses on documenting and explaining patterns of childhood mortality at three scales: the city/region, the neighbourhood, and the individual household. Using a case study approach, aggregate infant mortality rates for cities in Ontario between 1881-1941 were documented at five year intervals. Contrary to expectations, city size, population density and household crowding did not explain the variation in urban mortality rates. Instead, the socio-cultural composition of the population explained the greatest share of the mortality variation at the inter-urban scale. Analyses of Toronto in 1901 at the individual household and neighbourhood scales utilise data collected from individual-level death records, which were manually linked to the manuscript Census of Canada and tax assessment rolls. Results of the household level bivariate analyses reveal that social class (assessed value of home), housing conditions (crowding) and socio-cultural affiliation (religion, nativity, ethnicity) were independently associated with childhood mortality. Multivariate analysis confirmed these findings, and pointed to the importance of religion and crowding in particular. At the neighbourhood scale, analysis of the social geography of Toronto indicated a greater level of residential segregation by ethnicity and religion than previously understood. Childhood mortality varied a good deal from one neighbourhood to another, but not in the expected or predicted ways. Mortality rates were equally high in suburban fringe areas and inner city slums, and these variations could not be explained by social class or housing conditions, rather cultural affiliation had the strongest influence. In this regard, cultural background, but not necessarily immigrant status, was the most important determinant of mortality patterns at all three scales of analysis.

abstract: Doctor of Philosophy (PhD)


title: Dynamic and stable regulation of pyruvate dehydrogenase in human skeletal muscle

contributor:
Heigenhauser, George J.F.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: The mechanisms regulating the rate-determining enzyme of carbohydrate oxidation, pyruvate dehydrogenase (PDH), were examined in human skeletal muscle at rest and during exercise in response to acute respiratory alkalosis and short- and long-term aerobic training. Voluntary hyperventilation-induced respiratory alkalosis (R-Alk) delayed PDH activation during the transition from rest to submaximal exercise. A mismatch between pyruvate production and its oxidation in R-Alk resulted in a 35% higher lactate accumulation. These effects were not seen during steady state exercise. The results from this study suggest that respiratory alkalosis may play an important role in lactate accumulation during the transition from rest to exercise in acute hypoxic conditions, but that other factors mediate lactate accumulation during steady state exercise. Short-term aerobic training did not alter resting skeletal muscle total PDH (PDHt) and PDH kinase (PDK) activities, or their respective protein expressions compared to pre-training. In contrast, long-term aerobic training (Post) compared to pre-training (Pre) resulted in a 31% increased total PDHt activity, partially due to a 1.3 fold increased protein expression of a PDH subunit, PDHE 1 α. Despite the increased PDHt activity post-training, there was an approximate 37% attenuated activation of PDH Post after 15 min of exercise at the same absolute submaximal workload compared to Pre. PDK demonstrated a 2 fold increased activity Post, partially attributed to a 1.3 fold increased PDK2 isoform protein expression. The training-induced increased PDK2 isoform expression, pyruvate-sensitive PDK isoform, coincided with an attenuated skeletal muscle pyruvate content Post during submaximal exercise at the same absolute workload. The results of these findings suggest that aerobically trained human skeletal muscle has an increased maximal capacity to utilize carbohydrates, evident by increased PDHt, but increased metabolic control sensitivity to pyruvate during submaximal exercise through increased contribution of PDK2 to total PDK activity.

abstract: Doctor of Philosophy (PhD)


title: Microbial-Mineral-Trace metal interactions in acid rock drainage biofilms: Integrating macro-, micro-, and molecular-level techniques to understand metal behaviour

contributor:
Warren, Lesley A.
School of Geography and Geology

subject: Geography Geology Geography

abstract: In this study a combined field and laboratory approach was used to identify the bio-geochemical processes that control trace metal (Ni, Co, Cr) reactive transport within natural acid rock drainage (ARD) biofilms, over both diel and seasonal timescales. Results indicated that metal (Mn, Ni, Co and Cr) scavenging by these biological solids is stable on a seasonal time frame. Metal scavenging occurs within two key solids, they organic constituents of the biofilm (Ni, Co) and associated biogenic hydrous Mn oxyhydroxides (HMO; Ni, Co and Cr), and not in association with Fe-oxyhydroxy-sulphates which dominate the mineralogy of the biofilm oxic-anoxic boundary, a microbially controlled process. The reactivity and sorptive capacities of synthetic HMO analogs for Ni were further examined under well-characterized laboratory conditions. Analysis of the local chemical environment of Ni sorbed to HMO by synchroton-based X-ray absorption spectroscopy was integrated with a bulk geochemical model of the acid-base characteristics of HMO and a theoretical model of the HMO structure. The synergistic use of these techniques allowed unique insight into the structural reactivity of HMO for Ni and is the first study to mechanistically demonstrate why bulk surface complexation models (SCM) are not accurate for HMO metal uptake. Overall, the results of this thesis highlight the utility of combined field and laboratory investigation to characterize relevant processes for reactive metal transport and underscore the need to: (1) consider microscale microbial-geochemical linkages in geochemical behaviour; (2) use caution when applying results derived from synthetic analogs to interpret natural system behaviour; and (3) examine processes at the appropriate scale e.g. microscale, to evaluate the mechanisms involved in metal reactions with solids

abstract: Doctor of Philosophy (PhD)


title: The Design of a Cost-Effectiveness Analysis Within a Concurrent Randomized Clinical Trial of the Hamilton-Wentworth Chronic Home Care Programme

contributor:
Stoddart, G.L.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
The economic analysis described in this thesis is designed to compare two alternate approaches to post-hospital treatment for a specified group of chronically ill patients who are aged 65 and over and eligible for Home Care at the point of discharge from acute hospitals. Relative costs and health effects will be compared between the Hamilton-Wentworth are programme and the "no programme" situation or the usual of treatment without Home Care, using a cost-effectiveness model. Data will be collected from the Home Care group (experimental) and the No Home Care group (control) in a concurrent randomized clinical trial of the Home Care programme for the specified patients of interest. Costs will be measured as described herein. Health effects of interest will be physical function, social function and morale.

The completed results of the study will provide needed information about the magnitude and distribution of costs in each programme alternative for this specific group of patients in Hamilton-Wentworth and about the relation of costs to health effects. The analysis will have relevance to the Hamilton-Wentworth programme and to the Ontario Ministry of Health, as well as planners of similar programmes for similar groups of patients and the patients themselves. The data should add to the growing body of knowledge about the economics of Home Care programmes.

The methods developed here for measuring cost in a variety of services and for collection of health service utiIization data could be applied to other studies of similar community-based, multiservice programmes in relation to either specific patient groups or the overall programme impact. The models used for analysis and health effects within the context of a randomized trial should be applicable to other health care evaluations.

abstract: Master of Science (MS)


title: Energy Balance and Runoff in the Eastern Arctic

contributor:
James, Wm.
Civil Engineering

subject:
Civil Engineering
Civil Engineering

abstract:
Extensive interest in the exploitation of the natural resources of the Canadian High Arctic has been generated by the petrochemical and mining industries. This, in conjunction with the recent rapid growth of many communities in the Arctic has resulted in the need for reliable sources of potable water. Basic data deficiencies in the Arctic however preclude the use of traditional techniques for predicting the temporal distribution of runoff or peak from rates.

An interactive computer program using a modified energy budget concept has been developed to permit the simulation of average daily discharges from small watersheds in the Baffin region. All available hydrometeorologic data are utilized by the model which is formatted in a manner to facilitate data manipulation. Sensitivity analyses can thus be carried out to determine the sensitivity of a watershed's response to various meterologic parameters.

Calibration and subsequent verification of the model against data collected from two watersheds in the Baffin region yielded a high correlation between recorded and simulated discharges.

abstract: Master of Engineering (ME)


title: Therapy for Persistent Clinically Significant Gastro-oesophageal Reflux: The Design of a Randomized Clinical Trial of Surgical versus Medical Management

subject:
Medical Sciences
Medical Sciences

abstract:
Every day a physician treating patients carries out a series of experiments - whether he is aware of it or not. Many of the decisions he makes need to be made against a background of inadequate information concerning the effectiveness of the therapies he prescribes.

This manuscript begins with a review of the currently available scientific literature concerning gastro-oesophageal reflux - its pathogenesis, diagnosis and therapy. Then, the design of a prospective randomized control trial of therapy for persistent clinically significant gastro-oesophageal reflux is described. The design is for an intervention study to determine the effectiveness of therapy in patients randomized to either surgical or medical treatment for this disorder.

Subjects for the study will be drawn from among patients referred from primary care physicians to gastroenterology clinics for treatment. These patients to be eligible will have to have failed to respond to standard medical therapy.

Data for analysis will be collected utilizing a self administered questionnaire to record symptoms and the degree of incapacity caused by them.

It is hoped that results obtained from the performance of the trial described in this document will be of assistance in guiding the decision making process of physicians caring for patients with symptomatic gastro-oesophageal reflux.

abstract: Master of Science (MS)


title: The Conception of "nien-fo" in the Ching-t'u-shih-i-lun (Treatise on the Ten Doubts Concerning the Pure Land)

contributor:
MacQueen, Graeme
Religious Studies

subject: Religion Religion

abstract:
This thesis examines the conception of "nien-fo" (literally, "thinking of the Buddha") in the Ching-t'u-shih-i-lun, an eighth century Chinese text on the Buddha Amitābha and his Western Pure Land.

Nien-fo has always been an important part of religious practice for many different schools of Buddhism in China, especially for the T'ien-t'ai and Pure Land schools. In T'ien-t'ai Buddhism, the nien-fo samādhi is considered as a means to accomplish concentration and insight; it is but one among the various methods of mediatation. Considered as such, the nien-fo practice implies that salvation is achieved through the practitioner's own diligent cultivation of mind. On the other hand, the Pure Land nien-fo samādhi is essentially devout invocation of tho name of Amitābha Buddha. Nien-fo as invocation emphasizes salvation as an act of the Great Compassion of Amitābha. The concern of this thesis is to clarify the link between these fundamental meanings of nien-fo in the context of one particular text in which both forms or the practice appear.

The first chapter gives an overview of the T'ien-t'ai and Pure Land practices of nien-fo based upon a careful analysis of relevant passages taken from standard works of the two schools.

The second chapter undertakes a thorough examination of the nien-fo concept in the Ching-t'u-shih-i-lun.

The thesis concludes with a look at the relationship between the meditational and devotional paths to salvation in Chinese Buddhism. The two paths are essentially related, expressing two aspects of the bodhisattva path.

abstract: Master of Arts (MA)


title: Investigation And Separation of Nitrofurazone-DNA Derivatives Produced by Ɣ-Radiation

contributor:
McCalla, D.R.
Biochemistry

subject: Biochemistry Biochemistry

abstract: Gamma irradiation (¹³⁷Cs) of aqueous solutions of DNA and ¹⁴C-nitrofurazone (NF), labelled in the semi-carbazone moiety, produced DNA to which NF was covalently bound. Maximum binding occurred under hypoxic conditions. The binding was first order with respect to DNA concentration and was independent of NF providing excess drug was present. Enzymatic hydrolysis of the purified labelled DNA to the nucleotide and nucleoside stages was achieved in volatile buffers. Chromatographic separation of the various components in nucleotide and nucleoside hydrolysates was examined on Sephadex G-50, G-25, G-10, DEAE A-25, and AG 50WX4 columns. The AG 50WX4 column provided good clean preliminary separation of the NF derivatives from normal nucleosides and separation of derivatives into four groups. The Sephadex DEAE A-25 column allowed a more complete separation of NF derivatives. Single stranded DNA exhibited enhanced binding of NF over double stranded DNA. Nucleoside hydrolysates gave different proportions of the NF derivatives from irradiated single stranded or double stranded DNA. Deoxyribohomopolymers were used to assess the origin of the NF derivatives. Two major derivatives were common to all deoxyribohomopolymers suggesting ribose or phosphate derivatives. The other two groups of derivatives had UV absorption between 270 and 250 nm and appeared to be somewhat acidic in nature as assessed by their mobilities on ion exchange columns.

abstract: Master of Science (MS)


title: Cold-Cracking Control in Low-Alloy Steel Welds

contributor:
Kirkaldy, J.S.
Metallurgy and Materials Science

subject:
Materials Science and Engineering
Metallurgy
Materials Science and Engineering

abstract:
BAZ microstructure stress and hydrogen level are the fundamental factors influencing the cold cracking susceptibility of the HAZ. Implant testing at various hydrogen levels over a range of steel compositions and heat inputs shows how the microstructure and hydrogen level influence the critical stress necessary for cold-cracking.

Based on implant test data, a correlation formula predicting the critical stress necessary for cold cracking for given HAZ hardness martensite in the HAZ and hydrogen level, is proposed. Employing this correlation, together with prediction of martensite in the HAZ and HAZ hardness, based on heat transfer caculations, martensite-composition-cooling rate relations and hardness-composition-cooling rate relations, an algorithms which can predict the critical stress necessary for cracking for given implant composition, cooling rate and hydrogen level, is constructed.

This method of predicting the critical stress necessary for cold cracking is an improvement over the existing regression formulas for estimating cold-cracking susceptibility.

This formula has been successfully adapted to predict cold-cracking susceptibility data as obtained through other tests such as rigid restraint, and to recommend prehear levels necessary to avoid cold-cracking. Development and use of implant testing machine with an automatic welding and loading facility is also reported.

abstract: Master of Engineering (ME)


title: A Study of Methylmercury Exposure in Northwestern Ontario

contributor:
Roberts, R.S.
Clinical Epidemiology

subject:
Life Sciences
Life Sciences

abstract:
This thesis is a study of chronic methylmercury exposure in two Indian Reserves in Northwestern Ontario - White Dog and Crassy Narrows.

The study consists of three major divisions which are the analysis of trends in human mercury levels in the two communities from 1970 to 1978; the design of a study to examine three major research questions; and conclusions drawn from the study.

The analysis of data from White Dog and Grassy Narrows indicate that mean human mercury levels have declined significantly in the 1970 to 1978 period. This attributed to the success of programs designed to discourage the consumption of local fish.

A cross-sectional prevalence study is designed to address the question concerning possible neurological effects of chronic methylmercury exposure in White Dog and Grassy Narrows. A second sub-study utilizes a sample of individuals for whom early information is available on peak mercury levels to examine the question of a mercury exposure gradient. A retrospective study of stillbirths and congenital abnormalities is designed to examine the effect of prenatal exposure to methylmercury.

abstract: Master of Science (MS)


title: Image-derived plasma input function for the quantification of positron tomography brain studies with 6-[fluorine-18]-fluoro-L-meta-tyrosine

contributor:
Nahmias, Claude
Medical Physics

subject: medical physics

abstract: In this thesis, a method that extracts the time course of radioactivity concentration in the blood from brain PET images is developed as a non-invasive alternative to arterial blood sampling. Even though the methodology is developed for 6-[18 F]fluoro-L-m -tyrosine (Fm T), a presynaptic dopaminergic radiotracer, it is generalisable to other radiotracers. The method is based on predefined regions of interest (ROI) drawn on the largest cerebral blood vessels, the venous sinuses, which are visible in the PET images. The time course of radioactivity in the cerebral blood was initially corrected for partial volume and spillover using a population value for the calibre of the blood vessel. The method was refined by parametrising the ROIs in order to extract the calibre of the blood vessel directly from PET images and to simultaneously correct the radioactivity concentration for partial volume and spillover. In a validation study, the radioactivity concentration was recovered to 100 ± 4% in syringes filled with an 11 C solution and inserted into a water-filled cylindrical phantom. Even though the diameter of syringes was estimated with an accuracy of half a pixel (1mm) in the phantom studies, the method systematically overestimated the blood vessel calibre by 2-3mm compared with measurements made in magnetic resonance venograms in human studies. The application of the parametric ROIs method to clinical studies awaits the development of more accurate scatter correction methods and the implementation of correction for head motion. The between-subject variations in the blood vessel calibre were measured to be comparable to the bias given by the parametric ROIs, thereby justifying the use of a population value over current subject-specific values. A compartmental model relating the radiotracer Fm T, its main radiolabelled metabolite and their exchange between plasma and erythrocytes was also developed in order to transform the time course of total radioactivity measured in whole blood into the time course of the unmetabolised radiotracer in plasma. Presynaptic dopamine function is severely disturbed in Parkinson's disease (PD) with a pattern of striatal involvement (posterior putamen dopamine levels decreased compared to that in caudate nucleus on the side opposite to the clinically impaired limbs) that distinguishes it from other movement disorders. Compared to arterial blood sampling, the image-derived plasma input function enabled the discrimination of normal and PD subjects as well as the identification of the affected and unaffected sides of the PD subject. The image-derived plasma input function also classified 20 of the 21 consecutive patients suspected of suffering from a variety of movement disorders into the same categories as determined using an indirect cerebellar input function. Using image-derived input functions, quantitative analyses of PET/Fm T studies are feasible in a clinical setting and, in combination with striatal patterns of Fm T uptake, the method provides useful diagnostic information in individual patients. (Abstract shortened by UMI.)

abstract: Doctor of Philosophy (PhD)