title: A study of fracture in brittle laminar composites that contain weak interlayers

contributor:
Nicholson, P.S.
Materials Engineering

abstract:
Ceramics have material properties that make them useful for many industrial applications. They are strong, hard, and chemically inert. Their refractoriness gives them an advantage over metals and polymers for use at high temperature. Unfortunately, the inherent brittleness of ceramics limits their use in structural applications.

One way to improve the toughness of ceramics is to combine them with other materials to make composites. The correct combination of materials can lead to synergism, and a significant improvement in properties. In this work, brittle laminates that contain weak interlayers are considered. The weak interlayers lead to crack deflection, and can result in non-catastrophic failure of the material. The requirements for consistent crack deflection and non-catastrophic failure are not fully understood.

This work is an attempt to explain the observed fracture behaviour in brittle laminar composites that contain weak interlayers. A combination of experimental work, fracture mechanics modeling and finite element modeling has been used to predict the requirements necessary for non-catastrophic failure.

The work shows the size of flaws in the surface of the composite, in the weak interlayer, and in subsequent strong layers in the material, all play an important role in the fracture behaviour. Control and understanding of the effect of the various flaw sizes can be used to achieve non-catastrophic failure and increased work of fracture in these composites.

abstract: Doctor of Philosophy (PhD)


title: Evolutionary Rates and Patterns in Rodent APRT Sequences

contributor:
Golding, Brian G.
Biology

subject: Biology Biology

abstract: The nonrandom rates and patterns of sequence evolution found in the adenine phosphoribosyltransferase gene (APRT) from closely related rodent species provide insight into processes involved in molecular evolution. The rodent APRT phylogeny supports the species phylogeny tree previously found using morphological and molecular data. A five-fold slower rate of evolution observed in Mus spicilegus APRT compared to Mus musculus promotes M. spicilegus as a model species to test potential causes of rate variation between species, which may be related to a difference in degree of commensalism experienced by these two species. Rate differences found between individual exons and introns of the APRT, exemplified by the burst of substitutions observed in M. musculus, APRT exons I and V, suggest that regional differences in selection and mutation biases exist. Rate differences between sequence positions are demonstrated with some APRT third codon positions being more prone to substitution than others, indicating local effects on molecular evolution. The directional pattern of evolutionary changes found in the rodent APRTs suggests influences that can be attributed to selection and mutation biases which are possibly affected by sequence content and context. Observed directional patterns include: a distribution of substitutions along the sequence which is influenced by mutation bias and sequence base composition; substitution spectra which result in a net decrease in G/C content throughout rodent APRT evolution: substitutions at dinucleotides that reduce the presence of those dinucleotides in the sequence: and biased codon usage influenced by selection and CpG deamination. The limited divergerice between the rodent APRTs sequenced for this thesis provides strong evidence for the existence of rate differences and detectable patterns in substitutions that provide an intriguing view of the complex nature of molecular evolution and the processes involved. More divergent sequences might not reveal these patterns.

abstract: Doctor of Philosophy (PhD)


title: Regulation of Human Antithrombin Gene Expression. (1) Mapping of a Deletion Including in Part the Promoter Region. (2) Characterization of Cis-Acting Elements and Transcription Factors Binding to This Region

contributor:
Blajchman, Morris A.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: This thesis addresses regulatory aspects of the constitutive expression of human antithrombin, a serine-protease inhibitor involved in coagulation and thrombosis. An introductory part describes a 5'partial deletion, 480 nt upstream of the third exon of an antithrombin allele, in a kindred with thrombosis and hereditary deficiency in antithrombin. The lack of expression of the abnormal allele prompted the further characterization of elements regulating transcription in the 5' region of the normal antithrombin gene. Two cis-acting elements were found, both able to promote transcription in HepG2 and Cos I cells. The first promoter, at -150/+68 nt, encompassed the presumed transcriptional start site. The second element, in reverse orientation in regard to the first, was located at +895/+391 nt in the first intervening sequence. Following footprint analysis, it was shown that the 5'upstream promoter interacted with trans-acting factors at -92/-65 nt, -11/+37 nt and -124/-10 nt, in nuclear extracts from hepatic or non-hepatic origin. Several transcription-factors were subsequently identified, which interacted with these three elements either through direct binding or heterodimerization; they were the liver-enriched factors HNF4 and C/EBPα as well as the ubiquitous nuclear hormone receptors COUP-TF1, RXRα, PPARα and TRα. Furthermore, in vivo expression in HepG2, HeLa and BSC40 cells, of HNF4, C/EBPα and RXRα increased the efficiency of the 5'upstream promoter, while expression of COUP-TFl, TRα, HNF3α or β repressed the efficiency of the latter promoter and the activating effects of HNF4. In addition, activation by HNF4 was synergized by co-expression of RXRα in BSC40 and HeLa cells. These results suggest that the interplay of liver-enriched and ubiquitous factors modulates the constitutive expression of the antithrombin gene.

abstract: Doctor of Philosophy (PhD)


title: Gifts and Commodities on a Tongan Atoll: Understanding Intention and Action in a MIRAB Economy

contributor:
Cooper, M.
Anthropology

subject: Anthropology Anthropology

abstract:
A number of recent works on Tonga have emphasised the growing salience of the cash economy in the lives of the people of Tonga. For many authors the growth of the cash economy seems to indicate a transparent transformation of Tongan society from a traditional one to some form of capitalist/class-based society. Based on work undertaken in the Ha'apai region, I argue that while the impact of merchant capital, the growth of remittances as a source of household income, and the growth of the aid/bureaucracy/government nexus have indeed monetized the Tongan economy, the significance of the cash economy is mediated, and perhaps even subsumed, by social relations formed and reproduced within a distinctly non-capitalist form of production and exchange.

In the relative absence of the penetration of capitalist relations of production, and in the presence of a vibrant and relatively autonomous subsistence economy, social relations of production and exchange continue to have a distinctly traditional (or perhaps neo-traditional) character. While some elements of these relations can be seen to have developed in articulation with the world system, the transformative potential has been mitigated and mediated by gift exchange ideology and practice. Key elements in the rather unique history of Tonga (most significantly the non-commoditization of land) have in fact actively inhibited the commoditization of village life. Overseas migration is one of the primary ways in which Tongan villagers are integrated into the world system today. The way that migration is shaped by village based ceremony and gift exchange serves as one example of the continuing salience of social ties extending from rural Tonga into the world.

abstract: Doctor of Philosophy (PhD)


title: Optoelectronic Properties of Poly(p-phenylene vinylene) For Application in Light Emitting Devices

contributor:
Xu, Gu
Materials Science and Engineering

subject:
Materials Science and Engineering
Materials Science and Engineering

abstract:
Organic electroluminescent devices (OLED's) have been intensely researched in recent years. Poly(p-phenylene vinylene) (PPV), due to its ease of processing and potential high quantum yield, is considered a good candidate for future display applications. By synthesizing PPV films and fabricating PPV-based organic ELD's, optoelectronic properties of this conjugated polymer were investigated. The PPV synthesis was modified to improve material quality which affected device stability, lifetime, and luminescent yield.

By utilizing transmission electron microscopy, the presence of PPV crystals which lowered the quantum yield was thoroughly investigated. Electron micrographs revealed that aggregates of crystals were embedded in an amorphous matrix. Analysis of diffraction patterns established that NaCI was a major impurity and that its crystals acted as nucleation sites. Steps were accordingly taken to exclude NaCI and prepare a more amorphous material.

Impedance spectroscopy was used to measure conductivity and the activation energy. The low activation energy suggested carrier transport via hopping between localized states. Furthermore, the presence of a metal/polymer interface, which limited charge injection into the sample and lowered the efficiency, was identified. By controlling the parameters affecting device/material preparation, this interface was to a great extent improved.

Electroluminescent devices with areas of 40 mm² were fabricated. These devices could draw currents of up to 0.2 mA/cm² and emit a yellowish green light, visible under laboratory lighting at various viewing angles. An external efficiency of 0.4 LumlWatt was attained. A conservative internal efficiency of 0.59%, significantly higher than the ones previously reported for single layer organic devices, was calculated. The threshold voltage was reduced to 2-5 volts and stable OLED's with a lifetime of over 160 hours were fabricated.

The photovoltaic effect in PPV was explored by employing delayed-collection-field and field-induced fluorescent quenching techniques. A carrier generation efficiency of 42% was obtained. The strong field dependence of the carrier generation efficiency was noticed which supported the formation of bound electron-hole pairs.

abstract: Doctor of Philosophy (PhD)


title: Multivariate Statistical Regression Methods for Process Modelling and Experimental Design

contributor:
MacGregor, John F.
Chemical Engineering

subject:
Chemical Engineering
Chemical Engineering

abstract:
In this thesis, various multivariate statistical regression methods are investigated for estimating process models from the process input-output data. These identified models are to be used for designing model based controllers and experimental optimisation of multivariate processes. The following issues are explored: (i) identification of finite impulse response models for model based control; (ii) multi-output identification tor multivariate processes; (iii) recursive updating of process models for adaptive control and prediction; and (iv) experimental design in latent variables for high dimensional systems.

In the first part of the thesis, various approaches to identifying non-parsimonious finite impulse response (FIR) models are compared on the basis of closeness of fit to the true process, robust stability provided by the resulting model, and the control performance obtained. The major conclusion by all assessments is that obtaining FIR models by first identifying low order transfer function models by prediction error methods is much superior to any of the methods which directly identitY the FIR models.

In the second part, the potential of multi-output identification for multivariate processes is investigated via simulations on two process examples: a quality control example and an extractive distillation column. The identification of both the parsimonious transfer function models using multivariate prediction error methods and of non-parsimonious FIR models using multivariate statistical regression methods such as two-block partial least squares (PLS2), canonical correlation regression (CCR), reduced rank regression (RRR) are considered. The multi-output identification methods provide better results when compared to the single-output identification methods based on essentially all comparison criteria. The benefits for using multi-output identification are most obvious when there are limited amount of data and when the secondary output variables have better signal to noise ratios.

In the third part of this thesis, an improvement to the PLS algorithm is made. It is shown that only one of either the X or the Y matrix needs to be deflated during the sequential process of computing latent vectors. This result then leads to two very fast PLS kernel algorithms. Using these improved kernel algorithms, a new and fast recursive, exponentially weighted PLS algorithm is developed. The recursive PLS algorithm provides much better performance than the recursive least squares algorithm when applied to adaptive control of a simulated 2 by 2 multivariable continuous stirred tank reactor and updating of a multi-output prediction model for an industrial mineral flotation circuit.

Finally, a design methodology similar to the evolutionary operation (EVOP) and the response surface methodology (RSM) for optimisation of high dimensional system is proposed. A variation of the PLS algorithm, called selective PLS, is developed. It can be used to analyse the process data and select meaningful groupings of the process variables in which the EVOP/RSM experiments can be performed.

abstract: Doctor of Philosophy (PhD)


title: Parental Treatment And Offspring Differentiation: An Evolutionary Analysis

contributor:
Daly, Martin
Psychology

subject: Psychology Psychology

abstract: This thesis presents research on the nature of human kinship interactions, with special emphasis on birth order and its relationship to discriminative parental treatment of offspring and the development of within family differences. These issues are looked at through the lens of evolutionary psychology, a brief explanation of which is given in chapter 1. Chapter 2 is a theoretical and empirical critique of the applicability of a recent theoretical analysis of family relations in the animal kingdom in general to the specific case of human family relations. Chapters 3 and 4 focus specifically on birth order and parent-offspring relations, and their potential relationship to important life decisions, such as the age at which children leave home, and the amount of education they receive, among other things. Chapter 5 presents work on birth order, or rather, hatch order, and parent-offspring and sibling-sibling relations in a non-human animal, the herring gull, and serves to highlight the close integration of theory that exists between evolutionary psychology and animal behavior. The human and herring gull work represented here are both predicated on the same theoretical groundwork. The different ways in which these influences are played out is a function of the different ecology of these two species.

abstract: Doctor of Philosophy (PhD)


title: Bioremediation in a Porous Medium: Modelling, Theory and Applications

contributor:
Chadam, J.
Mathematics

subject: Mathematics Mathematics

abstract: A model for bacterial remediation of wastes in a porous medium is proposed. The mathematical model consists of a coupled set of nonlinear partial differential equations and an ordinary differential equation. Basic existence, uniqueness and regularity of this system have been studied in three space dimensions, globally in time. The existence of travelling wave solutions has also been proved. A free boundary problem has been formally derived in the limit of large solid density and the shape stability of the moving reaction interface has been studied using bifurcation methods along with numerical computations. It has been proved that the planar solution to the free boundary problem is the limit of the travelling wave solutions as the solid density becomes large. In some cases, shaped (not planar) reaction interfaces have been found which are unstable. During the early phase of remediation (when the bacteria are capable of freely moving from waste sites already occupied by other bacteria, effectively reducing the viscosity) planar reaction fronts are stable. On the other hand, during later phase (when the concentration of bacteria is high and crowding, effectively increasing the viscosity) planar reaction fronts are unstabIe. This could lead to fingering in the fronts which would result in some of the wastes being inaccesible to the bacteria, greatly reducing the effectiveness of this as a remediation process.

abstract: Doctor of Philosophy (PhD)


title: Neural space mapping methods for modeling and design of microwave circuits

contributor:
Bandler, John W.
Electrical and Computer Engineering

subject:
Electrical and Computer Engineering
Electrical and Computer Engineering

abstract: This thesis contributes to the development of novel methods and techniques for computer-aided electromagnetics (EM)-based modeling and design of microwave circuits exploiting two previously unrelated technologies: space mapping (SM) and artificial neural networks (ANNs). The conventional approach to EM-based modeling of microwave circuits is reviewed, as well as other state-of-the-art neuromodeling techniques. The fundamental space mapping concept is also reviewed. Developing neuromodels based on space mapping technology is addressed. Several SM-based neuromodeling techniques are described. Contrast with other neuromodeling approaches is realized. An algorithmic procedure to design, called Neural Space Mapping (NSM) optimization, is described. NSM enhances an SM-based neuromodel at each iteration. Other techniques for optimization of microwave circuits using artificial neural networks are reviewed. Efficient EM-based statistical analysis and yield optimization of microwave components using SM-based neuromodels is described. Other yield-driven EM optimization strategies are briefly reviewed. An innovative strategy to avoid extra EM simulations when asymmetric variations in the physical parameters are assumed is described. Neural Inverse Space Mapping (NISM) optimization for EM-based microwave design is described. A neural network approximates the inverse mapping at each iteration. The NISM step simply consists of evaluating this neural network at the optimal empirical solution. NISM step is proved to be a quasi-Newton step when the amount of nonlinearity in the inverse neuromapping is small. NISM optimization is compared with other SM-based optimization algorithms. The theoretical developments are implemented using available software on several advanced and industrially relevant microwave circuits. Suggestions for further research are provided.

abstract: Doctor of Philosophy (PhD)


title: American Regulation of Biomedicine: Liberal Humanism in Crisis

contributor:
Thomas, John E.
Philosophy

subject: Philosophy Philosophy

abstract:
Sociological studies indicate that American regulation of biomedicine is not achieving its goals. It is the purpose of this thesis to show that this is due more to an inadequate conceptualization of issues than to ineffectual implementation. It will argue that this conceptualization is determined by the origins of the American tradition of liberal humanism in the history of ideas, and that therefore the present social crisis has a theoretical counterpart in philosophy which must be examined.

In sum, this thesis describes the influence of Descartes, Hobbes and Locke on the founding of the American tradition. It identifies as the original point of theoretical difficulty Descartes' rational anthropology whose dualism ultimately produces an antagonism in American regulation of biomedicine between ethics and science and between individuals and society. Further it shows that because a rational anthropology characterizes man inadequately that American regulation cannot meet the theoretical requirements of liberal humanism and that, despite its roots in a rationalist natural law philosophy, it is gradually approaching biological pragmatism.

Finally this thesis concludes that philosophers and policymakers who would be faithful to the principles of liberal humanism within the context of biomedicine must show how the biomedicinal project of human self-creation can serve the moral process of human self-emancipation.

abstract: Master of Arts (MA)


title: Myopic Policies for Inventory Control

contributor:
Parlar, Mahmut
Love, Robert F.
Mohanty, Sri Gopal
Management Science/Systems

subject: Management Sciences and Quantitative Methods

abstract: In this thesis we study a typical retailer's problem characterized by a slngle item, periodic review of inventory levels in a multi-period setting: and stochastic demands. We consider the case of full backlogging where backorders are penalized via fixed and proportional backorder costs simultaneously. This treatment of backorder costs is a nonstandard aspect of our study. The discussion begins with an introduction in Chapter 1. Next, a review of the relevant literature is provided in Chapter 2. In Chapter 3 we study the infinite horizon case which is of both theoretical and practical interest. From a theoretical point of view tile infinite horizon solution represents the limiting behavior of the finite horizon case. Solving the infinite horizon problem has also its own practical benefits since its solution is easier to compute. Our motivation to study the infinite horizon case in the first place is pragmatic. We prove that a myopic base-stock policy is optimal for the infinite horizon case, and this result provides a basis for our study. We show that the optimal myopic policy can be computed easily for the Erlang demand in Chapter 4; solve a disposal problem which arises under the myopic policy in Chapter 5, and also study in Chapters 6 and 7 the finite horizon problem for which a myopic policy is not optimal. For the finite horizon problem computation of the exact policy may require a substantial effort. From a computational point of view, there is a need for developing a method that overcomes this burden. In Chapter 6 we develop a model for such a method by restricting our attention to the class of myopic base-stock policies, and call the resulting policy the 'best myopic' policy. We discuss analytical and numerical results for the computation of the best myopic policy in Chapter 7. Finally we present a summary of our main findings in Chapter 8.

abstract: Doctor of Philosophy (PhD)


title: Isotopic and dental evidence for diet from the necropolis of Isola Sacra (1st--3rd centuries AD), Italy

contributor:
Saunders, S.R.
Anthropology

subject: Anthropology Anthropology

abstract: This study investigates diet in the human skeletal sample from the necropolis of Isola Sacra, Italy (ca. 1st -3 rd centuries AD). Dietary patterns inferred from isotopic and dental health data are examined in relation to documentary and archaeological information on the diets of people in ancient Rome. The isotopic data indicate that the diet of this coastal population was a mixture of approximately 60% terrestrial and 40% marine resources. Males are enriched in 13 C and 15 N, suggesting a higher proportion of marine foods in their diet. There is some isotopic variability between age categories, but very little variation between different burial types in the cemetery. Comparison with a rural Roman sample reveals an isotopic distinction between consumers of predominantly terrestrial resources and those consuming a significant proportion of marine resources. Isotopic analysis of infant ribs suggests that weaning began around 3 months and lasted until 2 years of age, and that infants were fed a predominantly grain-based weaning diet. Caries, antemortem tooth loss (AMTL), tooth wear, abscesses, and calculus were examined, and they indicate a moderately good level of oral health in the Isola Sacra sample, consistent with evidence from other Roman period skeletal samples. Only calculus levels are significantly different between males and females, although males have higher levels of tooth wear and caries and females have higher levels of AMTL. There is no significant association between dental health and burial type. Overall levels of calculus, caries, and tooth wear in the deciduous teeth are low in this sample, but pathological lesions begin to appear as early as 2.5 years and tooth wear starts as young as 1.5 years. The combined use of isotopic and dental evidence provides insight into the diets and lives of this significant Roman period skeletal sample.

abstract: Doctor of Philosophy (PhD)


title: Finite element modelling of two-component, solid-liquid mixtures

contributor:
Stolle, D.F.E.
Civil Engineering

subject:
Civil Engineering
Civil Engineering

abstract: The scope of this thesis is to present a framework for the modelling of two-component, liquid/solid mixtures using the finite element method. The presentation is applicable to a wide range of two-component phenomena, however, special attention is paid to the liquefaction of sandy soils which is of particular concern to the civil engineer. In the past, much of the focus of research has been placed on the creation of models capable of capturing the mechanism of excess pore pressure development leading to liquefaction. Comparatively little attention has been placed on modelling the post-liquefaction event. This thesis provides a framework that allows the civil engineer to model soil deposits, predicting the onset of liquefaction and simulating the events that follow, namely post-liquefaction flow and the reconsolidation of the soil. The mixtures considered in this thesis are treated as two viscous fluids having momentum exchange between them via hydrodynamic drag. Two sets of Navier-Stokes equations are used to model the two-component mixture. The thesis presents the derivation of these equations along with the closure equations required to model the hydrodynamic drag and shear stress constitutive behaviour. A simple, novel approach to modelling the compaction/dilation behaviour of granular materials under the action of shear strain is also presented. It is shown that a recasting of the equations with anew set of variables is helpful in solving the equations via standard Galerkin finite element methods. An outgrowth of this recasting is also presented, that allows, for one-dimensional problems, to reduce the variable set from four unknowns to one, greatly simplifying the solution process and computation effort. Finally, several applications of the model are presented in order to validate the model and to demonstrate the wide range for which the model may be used.

abstract: Doctor of Philosophy (PhD)


title: Molecular gas in barred galaxy nuclei

contributor:
Dr, Christine D. Wilson
Physics and Astronomy

subject:
Astrophysics and Astronomy
Physics
Astrophysics and Astronomy

abstract: Double bars have been proposed as a means of transporting molecular gas past inner Lindblad resonances into the nuclear regions, where it can fuel active or starburst nuclei. Thus far, the existence of double bars has been determined by isophote twists seen in the near infrared, which could probe the bulge properties of these galaxies rather than the disk properties. We have observed two double bar galaxy candidates (NGC 2273 and NGC 5728) in 12 CO J = 1-0 with the Caltech Millimeter Array. Despite the similar near infrared images of the two galaxies, we see rather different nuclear morphologies in the CO maps. NGC 2273 shows evidence of a nuclear bar misaligned from the main stellar bar by ∼90°, and aligned with the near infrared isophote twists. NGC 5728 shows an arc of CO clumps that peaks just to the south-west of the dynamical center and curves to the south-east where it follows the dust lane to the south. The lack of a nuclear bar in the CO maps of NGC 5728 may be evidence that it is in a later stage of evolution. Bar dissolution may have just begun, and the gas has responded first, which may explain why we see a nuclear bar in the near infrared images of NGC 5728, but not in the CO maps. Models of these double barred galaxies show that the nuclear molecular morphology depends on the assumed gas properties. We have performed a multi-transition CO study of the nuclei of seven double barred galaxies that exhibit a variety of molecular gas morphologies in order to determine if the molecular gas properties are correlated with the nuclear structure and activity. We find that the 12 CO J = 3-2/J = 2-1 line ratio is lower in galaxies with molecular bars in the nucleus and higher in galaxies with CO emission dispersed around the galactic center. The galaxies without central concentration show signs of past star formation which may have exhausted, heated, and dispersed the molecular gas in the nucleus, resulting in the observed distributions and high CO line ratios. The multiline CO data corroborates our hypothesis that the galaxies with nuclear molecular bars are at an earlier stage of double barred galaxy evolution. In an attempt to detect other double barred galaxies that are bright enough in CO emission to be mapped at high resolution, we have undertaken a CO survey with the JCMT and NRAO 12-m of all double barred galaxies that are observable from the northern hemisphere. (Abstract shortened by UMI.)

abstract: Doctor of Philosophy (PhD)


title: In vivo measurements of aluminum and strontium in human bone

contributor:
Chettle, David R.
Medical Physics

abstract: This thesis investigated a means of improving bone aluminum measurement using neutron activation analysis which has been previously demonstrated for measuring trace and minor elements in human tissues. Currently, a KN Van de Graaff-accelerator was used with irradiation parameters of 2 MeV proton energy and 100 μA current, to activate aluminum via the 27 Al(n, γ) 28 Al reaction. A minimum detectable limit of 1.14 mg of aluminum in hand was achieved, accompanied with a hand dose of 48 mSv delivered to the subject. Further improvements in the sensitivity of aluminum assessment has been investigated by Monte Carlo modeling, and a new irradiation cavity has been proposed. The cavity design focused on increasing the thermal neutron flux to the hand, while providing additional shielding to the subject, and therefore, it should allow ethics approval for in vivo testing and application. A source-based x-ray fluorescence (XRF) technique of bone strontium was also developed. The designed XRF system was tested in vivo on ten subjects, successfully detecting the strontium quantities in the finger bone. Furthermore, three normalization techniques were investigated such as: coherent normalization, the strontium Kα/Kβ x-ray ratio and the Sr/Ca ratio in bone. The feasibility of normalizations show that none of the normalization can be reliably applied to healthy subjects. Therefore, an ultrasound measurement was an integral part of strontium XRF, as a means to measure overlying tissue thickness at the measurement site that was necessary for the estimation of bone strontium concentration during the course of this work.

abstract: Doctor of Philosophy (PhD)


title: Synthesis of alpha-allynyl and alpha-allylsilane amino acids by the Claisen rearrangement

contributor:
Brook, Michael A.
Chemistry

subject: Chemistry Chemistry

abstract: The enolate Claisen rearrangements of (E )-1-(alkylsilyl)-1-propen-3-ol-[ N -PG]-glycinate and (E )-1-(alkylsilyl)-l-buten-3-ol-[ N -PG]-glycinate esters were investigated (PG = protecting group). Several different variants of the Claisen rearrangement were evaluated; the formation of the syn stereoisomer was favored in all cases. The product was obtained in good to excellent yield (85-92%). The diastereoselectivity of the reaction varied from 2:1 to 29:1 (syn:anti ) depending on reaction conditions. In the case of the Ireland-Claisen variant, the relationship between enolate trap (R3 SiCl, R2 SiCl2 and Cl3 SiH) and diastereoselectivity was investigated, showing that chlorotrimethylsilane gave the best results in both selectivity and product yield. The size of the silyl group on the ester was also found to affect the diastereoselectivity slightly, in the sense that bulkier silanes improved reaction selectivity except in the case of aryl-substituted silanes. The Claisen rearrangement of 1-(alkylsilyl)-1-propyn-3-ol-[N -Boc]-glycinate ester and 1-(alkylsilyl)-1-butyn-3-ol-[N -Boc]-glycinate ester led to the formation of the unusual α-(3,5-bis(silyl)allenyl)-amino acid derivatives in moderate to good yield (30 to 85%) and high stereoselectivity (9:1 to 22:1). The amount of base (3.5 eq.) and enolate trap (3.5 eq.) employed in this reaction was found to be crucial for a high yield of the product. Diastereoselective additions of methyl-2-(N -PG)-3-(trimethylsilyl)-( E )-pent-4-enoate and methyl-2-(N -PG)-3-(trimethylsilyl)-( E )-hex-4-enoate to aromatic acetals in the presence of Lewis acids were investigated. Reaction conditions were examined in detail. TiCl 4 was found to be most effective in promoting the addition. Among the aromatic acetals examined, 2-bromo-benzaldehyde dimethyl acetal gave the best selectivity (>99% d.e.) and the best product yield (89%). The reaction of benzaldehyde dimethyl acetal resulted in modest selectivity (6:1) and yield (77%). BF3 .OEt2 promoted the addition reaction to give moderate yield and selectivity. The reaction of BF3 .OEt2 was found to be slower and required longer reaction times, to achieve high yield, than TiCl4 .

abstract: Doctor of Philosophy (PhD)


title: Carbenes and radicals from benzyloxy delta(3)-1,3,4-oxadiazolines

contributor:
Warkentin, John
Chemistry

subject: Chemistry Chemistry

abstract: Recently, dialkoxycarbenes bearing the appropriate carbene substituents have been reported to fragment to radical pairs at moderate temperatures (110°C). This dissertation investigates the fragmentation of dialkoxycarbenes bearing one or two benzyloxy groups to a radical pair or a diradical. Δ 3 -1,3,4-Oxadiazolines, which are established precursors of dialkoxycarbenes, were utilized to generate the benzyloxycarbenes. Dialkoxycarbenes bearing one of two benzyloxy substituents fragment to an alkoxycarbonyl and a benzyl radical and subsequent radical coupling afford phenylacetates, Scheme I. The rate constant for this fragmentation is estimated to be 107 s-1 . Utilizing benzyloxy( p -substituted-benzyloxy)carbenes the substituent effects on the fragmentation were studied. A preference for the cleavage to the benzyl group bearing the electron-withdrawing group was observed and this suggests that the transition state for fragmentation of benzyloxycarbenes is quite polar.* After establishing the homolysis of benzyloxycarbenes to radical pairs in solution, carbene traps were used to determine if these carbenes underwent intermolecular reactions with alkenes in competition with carbene fragmentation. Alkenes bearing two cyano groups (methylidenemalononitriles) were cyclopropanated by the benzyloxycarbenes followed by rearrangement of the cyclopropanes, Scheme II. Alkenes bearing substituents that are less electron withdrawing, such as phenyl and ester groups did not react with benzyloxycarbenes. Fragmentation of these carbenes was faster than their addition of the carbene to the alkenes and products from radical coupling and radical additions to the double bonds were detected.* The chemistry of a six-membered-ring dioxycarbene, 1,3-dioxa-4-phenyl-cyclohex-2-ylidene, was also studied. Fragmentation of 1,3-dioxa-4-phenyl-cyclohex-2-ylidene affords a diradical and some unique chemistry of this diradical was observed. Along with typical diradical chemistry, such as coupling, novel products from the intermolecular homolytic aromatic substitution of the diradical onto benzene and reaction of the diradical with acetone were isolated, Scheme III. Intermolecular reactions of diradicals are rare and coupling and disproportionation dominate. The unusual reactivity of this diradical is assumed to be related to the conformation in which it is born.* *Please refer to dissertation for diagrams.

abstract: Doctor of Philosophy (PhD)


title: Infrared properties of three low-dimensional materials

contributor:
Timusk, T.
Physics

subject: Physics Physics

abstract: This thesis includes far-infrared measurements of three new and very different materials, the spin-Peierls compound CuGeO3 , the quasi-two-dimensional organic superconductor κ-(ET)2 Cu[N(CN)2 ]Br, and the high-temperature superconductor HgBa2 Ca2 Cu 3 O8-δ . All three have reduced dimensionality and exhibit properties which are both of great interest to solid state physicists and ideal for study using far-infrared techniques. CuGeO3 is the first inorganic spin-Peierls compound to be discovered. It has a simple structure, is easily doped with impurities, and can be grown in the form of very large single crystals. These properties make it far easier to study than its organic predecessors. Like other spin-Peierls compounds, CuGeO3 consists of chains of large tightly bound blocks that can move as units, in this case GeO4 tetrahedra, and the spin-Peierls distortion can be described in terms of a displacement of these units. This thesis discusses a newly discovered local libration of the GeO4 tetrahedra near impurity atoms in doped CuGeO3 . This unusual mode is highly anharmonic and causes striking features in the far-infrared spectra. The superconductor κ-(ET)2 Cu[N(CN)2 ]Br belongs to a family of organic superconductors that, like the much studied high-temperature superconductors, consist of metallic sheets that are relatively isolated from one another. Conduction within the sheets is coherent, but the nature of the transport between the sheets is poorly understood. In this thesis, the first ever interplane far-infrared spectra for this material are reported. No evidence of coherent transport is found down to the lowest frequencies suggesting that in this respect this family of organic superconductors is similar to the high-temperature superconductors. Many internal modes of the ET molecule are also identified in the spectra. HgBa2 Ca2 Cu3 O8-δ has the highest superconducting transition temperature ever measured, but single crystals large enough for infrared and far-infrared studies have only recently become available. This thesis presents in-plane infrared measurements on this material that show the presence of a pseudogap much like that seen in other high temperature superconductors except that it is considerably larger in size. In fact, its pseudogap is larger than those of the other materials by the same factor by which its transition temperature is higher. This suggests a possible relationship between pseudogap size and transition temperature which is discussed in light of other results in the literature. All three of these materials are either quasi-one-dimensional or quasi-two-dimensional in nature and demonstrate both the diversity of the phenomena found in solid state systems and the utility of far-infrared spectroscopy in their study.

abstract: Doctor of Philosophy (PhD)


title: Impact of gel morphology on pore-filled membranes

contributor:
Childs, R.F.
Chemistry

subject: Chemistry Chemistry

abstract: Pore-filled cation exchange membranes were prepared by the co-polymerization of acrylic acid and N,N' -methylenebisacrylamide within the pores of a microporous polypropylene substrate. The poly(acrylic acid) gels in the membranes exhibited heterogeneity when synthesized with 1,4-dioxane, a poor solvent for poly(acrylic acid), or with increase in degree of cross-linking. Corresponding bulk gels were prepared and revealed heterogeneity as the volume percent of 1,4-dioxane was increased in the DMF mixture, or as the cross linking ratio was increased. Confocal laser scanning microscopy revealed a globular morphology of both the bulk gel and the pore-filling gel in the membrane when formed in a poor solvent. However, no difference in morphology was detected with the change in degree of cross-linking. The degree of swelling of the membranes was consistent with a change in gel morphology associated with change in reaction solvent or degree of cross-linking. The hydrodynamic (Darcy) permeabilities of the membranes were determined by measuring the fluxes at various pressures. The pure water-fluxes were found to be dependent on the mass-loading and morphology of the gel within the membranes. It was found that the permeability of the membranes decreased with increasing polymer volume fraction. The membranes were evaluated in terms of their nanofiltration capabilities with 5 mM solutions of NaCl. The extended Nemst-Planck equation, which takes account of the effective charge densities, was used to model rejection of single electrolyte solutions. The separation properties of the PAA membranes are good and the salt rejection was found to be practically constant, at constant pressure, over a wide range of gel concentrations. However, the performance was affected by the morphology of the gel. Asymmetric membranes were synthesized by photopolymerization of acrylic acid within a porous substrate. The monomer solution contained 2,2 ' -dihydroxy-4,4' -dimethoxybenzophenone (DDB), a UV absorber, which controlled the penetration depth of UV radiation. (Abstract shortened by UMI.)

abstract: Doctor of Philosophy (PhD)


title: A polarimetric study of magnetic fields in star-forming molecular clouds

contributor:
Wilson, Christine D.
Physics and Astronomy

abstract: I have used a recently commissioned, highly sensitive polarimeter at the James Clerk Maxwell Telescope to probe the magnetic field geometries of six star-forming regions within 500 pc of the Sun. For five of the regions, these are the first data produced of emission polarization from dust grains aligned by local magnetic fields. The variations in the polarization pattern across the clouds have been compared to predicted patterns from various models of magnetized molecular clouds. In several regions, particularly OMC-3 in the Orion A cloud, the polarization data are very consistent with predictions of a recently developed model of filamentary molecular clouds threaded by helical fields. The regions of NGC 2068 and LBS 23N could also contain helical magnetic field geometries. Although NGC 2024 is successfully modeled by a helical field, this geometry is not consistent with existing data of the line-of-sight magnetic field, which is not probed by polarization measurements. Instead, I suggest that the field geometry in NGC 2024 is that of an expanding ionization front from the associated HII region, bent around the dense ridge of star-forming cores. Prior to this work, most regions were thought to contain an ordered magnetic field component which was essentially unidirectional. Only one region in my sample contains a distribution of polarization vectors which could support such a geometry; in this cloud, Barnard 1, I have estimated the three-dimensional field strength and orientation associated with this "uniform" field and find a significant fraction of the field lies in the plane of the sky. This solution applies only to low column densities and not to the denser cores within Barnard 1, which do not exhibit alignment with the low density material. In short, this work reveals that unidirectional field geometries are not supported on intermediate scales within molecular clouds. Furthermore, no single magnetic field geometry is applicable in all molecular clouds; in each region, local environments and the associated physics must be taken into account.

abstract: Doctor of Philosophy (PhD)


title: Maintenance of Steel Mill Rolls for Flat Rolled Products by Roll Turning Lathe

contributor:
Tlusty, J.
Mechanical Engineering

subject:
Mechanical Engineering
Mechanical Engineering

abstract:
The thesis investigates roll turning for the maintenance of steel mill rolls at DOFASCO and culminates in the specification of a roll turning lathe. The thesis can basically be divided into three main categories: (1) The application of steel mill rolls for both hot and cold rolling processes, their requirements and characteristics.

(2) Present roll maintenance practices and machinery. All rolling mill rolls require a regular redressing to restore the specified surface quality and the specified cylindricity which is necessary to produce a high quality product. Roll surface conditions prior to machining are of particular interest. A new approach to the maintenance of steel mill rolls is investigated. This is the replacement of roll grinding, which is generally applied throughout the steel industry, by roll turning.

(3) The economic justification for roll turning leads to the development of specifications for the selection and procurement of a roll turning lather for the maintenance of steel mills rolls at DOFASCO.

abstract: Master of Engineering (ME)


title: Separate specific and nonspecific influences on the repetition effect: Implications for aging

contributor:
Milliken, Bruce
Psychology

subject: Psychology Psychology

abstract: The research reported in this thesis focuses on the cognitive processes that contribute to the repetition effect in a forced-choice discrimination task. The five experiments reported in the first manuscript suggest that the repetition effect is determined by two separate memorial influences. One influence is specific to the link between perception and action while the other influence reflects the prior action independent of the perceptual stimulus to which that action was made. The critical observation is that these two influences, specific and nonspecific, can work in concert or in opposition to modulate the repetition effect. The four experiments reported in the second manuscript focus on how these two processes, specific and nonspecific, change with age. There are two critical findings reported in this second manuscript: (1) the relative contribution of these two influences changes with age and (2) manipulating the testing time in young adults appears to be an excellent model for the study of aging. A further contribution of this thesis is that it illustrates the danger in assuming that repetition effects are process pure cognitive measures. Instead, it may be more appropriate for cognitive psychologists to focus on analytic techniques that allow the influence of separate processes on performance to be studied.

abstract: Doctor of Philosophy (PhD)


title: Generation and reactions of aryloxy and diaryloxycarbenes

subject: Chemistry Chemistry

abstract: The research work presented is mainly in the area of the physical organic chemistry of nucleophilic aryloxy and diaryloxycarbenes and their potential in synthetic applications. Some other intermediates, including dipolar intermediates or radicals, were also involved. 2,2-Diaryloxy-Δ3 -1,3,4-oxadiazolines and 2-aryloxy-2-methoxy-Δ 3 -1,3,4-oxadiazolines were synthesized by oxidation of the corresponding aryloxy or alkoxy carbonyl hydrazones of acetone followed by acid-catalysed exchange with different phenols. Subsequent thermolysis processes resulted in the generation of differently substituted diaryloxycarbenes and aryloxycarbenes. Cycloreversion to 2-diazopropane and corresponding carbonates was shown to be a competitive route. The intermolecular reaction of the diaryloxy or aryloxycarbenes with an electron-deficient alkyne, DMAD, resulted in interesting dioxyvinylcarbenes, which did a novel intermolecular aromatic substitution. A mechanistic study showed that the substitution was nucleophilic. A further study of the ortho substituent effect on the ipso aromatic substitution revealed a novel electronic effect, a through-space stabilization of a vinylogous dioxycarbene by an electron rich group. This interesting result has not been reported before. Its synthetic application needs further study. Thermolysis of a 2-acetoxy-2-aryloxy oxadiazoline resulted in some products that could only have come from radical reactions. Without any good radical stabilizing group, the fragmentation of a dioxycarbene to radical pairs is surprising.

abstract: Doctor of Philosophy (PhD)


title: The structures and dynamics of organometallic-arene complexes and bimetallic clusters

contributor:
McGlinchey, Michael J.
Chemistry

subject: Chemistry Chemistry

abstract: This thesis describes the synthesis, characterisation and molecular dynamics of several series of new arene-metal and cationic organometallic complexes, and the potential utility of these systems in synthesis. The first characterised organometallic complexes of trindane (the condensation trimer of cyclopentanone, and a potential synthetic precursor to the unknown molecule sumanene), are reported, and the possibility of derivatising trindane at the benzylic sites is discussed. The X-ray crystal structures of three trindane complexes reveal that sterically demanding groups affect the conformations of the cyclopentene rings. A series of hexaethylbenzene (HEB)-Ru complexes was investigated with respect to their HEB ligand conformations and dynamics in solution. The conformational versatility of HEB allowed a means of probing the stereochemistry and dynamics of these complexes, which were characterised by NMR spectroscopy and X-ray crystallography. A by-product of one reaction, the known complex trans -RuCl2 (PMe3 )4 , was found; the previously unreported X-ray crystal structure of this compound is described. The ideas of Bürgi and Dunitz (that a succession of static X-ray structures can provide information about the dynamics of a reaction) have been applied to finding the migration pathway of a CR2+ moiety in a series of bimetallic cluster cations, [Cp2 Mo 2 (CO)4 (HC=C-CR2 )]+ , from one molybdenum vertex to the other. The construction of an energy hypersurface for the migration of a C=CH2 fragment over a [Cp2 Mo2 (CO) 4 CH]+ triangular base reveals that the structure whereby the CH2 group is oriented directly over a metal vertex lies at the bottom of the potential energy well. The calculated migration trajectory between vertices is beautifully paralleled by a series of X-ray crystal structures of cations [Cp2 Mo2 (CO)4 (RC≡C-CR ' R'' )]+ . In dicobalt clusters, the preference of an alkynyl dicobalt hexacarbonyl moiety to occupy an equatorial position in ring systems has been extended to several alkynylcyclohexanols. The alkynol conformations are compared with the structures of the corresponding Co2 (CO)6 complexes, including structures where the Cot cluster competes with a tert -butyl group for an equatorial site. A mechanism involving migration of a carbocationic centre between cobalt vertices in a cluster is rationalised in light of these results.

abstract: Doctor of Philosophy (PhD)


title: Polyanions of the Heavy Group 13, 14 and 16 Elements in Basic Media

contributor:
Schrobilgen, G. J.
Chemistry

subject: Chemistry Chemistry

abstract:
This thesis describes the preparation and characterization of some classical cluster main-group polyanions in solution by multinuclear magnetic resonance spectroscopy (multi-NMR) and in the solid state by X-ray crystallography.

A novel series of classical anions, Pb2Ch3^2 (Ch = Se, Te) and M2Se3^2 (M = Sn, Pb), have been characterized in solution and the detailed geometry of Pb2Se3^2 and Pb2Te3^2 obtained from the crystal structures of (2, 2,2-crypt-K+)2 Pb2Ch3^2 (Ch = Se or Te) as determined by X-ray crystallography. The anions were found to have a trigonal bipyramidal structure with the Pb and/or Sn atoms in the axial positions and the chalcogen atoms in the equatorial plane.

The Sen^2 and Ten^2 (n = 1-4) anions and the new chain-like heteropolychalcogenide anions, TekSe2-k^2 and TepSe4-p^2 and (k = 1, 2 and p = 2, 3) have been characterized in solution and their chemical exchange behaviour directly observed by the NMR spectroscopy. The structures of these anions can be rationalized on the principle that the more electronegative atom is positioned at the sites of highest electron density. Furthermore, the large one-bond coupling constants observed for Cht-Chb bonds indicate that the nature of these bonds are significantly different from those of Chb-Chb bonds. The detailed geometry of the V-shaped TeSe2^2- (C2v) and the pyramidal TeSe3^2- (C3v) anions have been determined from the X-ray crystal structures of (2, 2, 2-crypt-K+) 2TeSen^2-.en (n = 2, 3). In addition, the TeSmSe3-m^2- anions (m = 0-3), have been characterized in soltuion. A significant involvement of π(d-p) bonds is evident in these species.

A new series of three-coordinated Sn(IV) telluride anions have been identified in solution by multi-NMR. The NMR data indicated the presence of polyanions consisting of linked trigonal planar SnTe3-units in which each SnTe3-unit is undergoing fast intramolecular "spinning" on the NMR time scale.

The extraction of K/Sn/Tl and K/Pb/Tl alloys in ethylenediamine and/or liquid ammonia gave rise to new polyatomic Tl-Sn and Tl-Pb cluster anions. The formation of the anions were found to be strongly dependent on the solvent used for the extraction and the presence of 2, 2, 2-crypt, as well as the alloy preparation method. The multi-NMR study indicated that the new Tl-Sn cluster anions were nonfluxional. The structure of two of the anions have been proposed, i.e., a bicapped square antiprism for Tl2Sn8^4- and a coupled TlSn3-tetrahedra for (Sn3TlTlSn3)^4-.

abstract: Doctor of Philosophy (PhD)


title: Inter- and Intramolecular Phenolic Hydrogen Atom Abstraction by Aromatic Ketone Triplets

contributor:
Leigh, W.J.
Chemistry

subject: Chemistry Chemistry

abstract: This thesis focuses on the joint detection of the model order and the estimation of the parameters of interest, with applications to array signal processing in both the off-line and on-line contexts. In the off-line mode, Markov Chain Monte Carlo methods are applied to obtain a numerical approximation of the joint posterior distribution of the parameters. The on-line approach uses the sequential implementation of Monte Carlo methods applied to probabilistic dynamic systems. Three problems were addressed in the course of this thesis. (1) A method for joint detection of the number of sources and estimation of their respective directions of arrival in coloured noise with unknown arbitrary covariance was developed. (2) The second algorithm represents an extension of the first one with the addition of the joint estimation of the times of arrival of the pulses, in the spirit of channel sounding for characterization of multipath channels. Both methods were successfully applied to real data, acquired on campus with a channel sounder during an extensive measurement campaign. (3) The final part of this thesis focuses on the sequential implementation of the Monte Carlo methods, i.e. particle filters, for probabilistic dynamic systems. The algorithm recursively estimates the posterior distribution of the evolving parameters of interest, allowing for the on-line detection of the number of sources and the estimation of their respective directions of arrival.

abstract: Doctor of Philosophy (PhD)


title: Advanced Bayesian methods for array signal processing

contributor:
Reilly, James P.
Electrical and Computer Engineering

abstract: Doctor of Philosophy (PhD)


title: Space mapping frameworks for modeling and design of microwave circuits

contributor:
Bandler, John W.
Electrical and Computer Engineering

abstract: This thesis contributes to computer-aided design and modeling of microwave circuits exploiting space mapping technology. Comprehensive frameworks for enhancing available empirical models or creating new ones are presented. A novel technique for microwave circuit design is also presented. A comprehensive framework to engineering device modeling which we call Generalized Space Mapping (GSM) is introduced. GSM aims at significantly enhancing the accuracy of available empirical models of microwave devices by utilizing a few relevant full-wave EM simulations. Three fundamental illustrations are presented: a basic Space Mapping Super Model (SMSM), Frequency-Space Mapping Super Model (FSMSM) and Multiple Space Mapping (MSM). Two variations of MSM are presented: MSM for Device Responses (MSMDR) and MSM for Frequency Intervals (MSMFI). A novel criterion to discriminate between coarse models of the same device is also presented. A new computer-aided modeling methodology to develop broadband physics-based models for passive components is presented. Full-wave EM simulators, artificial neural networks, multivariable rational functions, dimensional analysis and frequency mapping are coherently integrated to establish broadband models. Frequency mapping is used to develop the frequency-dependent empirical models. Useful properties of the frequency mapping are utilized in the modeling process. Transformations from frequency-dependent models to frequency-independent ones are also considered. The passivity conditions of the frequency-dependent empirical model are also considered. We present a novel design framework for microwave circuits. We expand the original space mapping technique by allowing preassigned parameters (which are not used in optimization) to change in some components of the coarse model. We refer to those components as "relevant" components and we present a method based on sensitivity analysis to identify them. As a result, the coarse model can be calibrated to align with the fine model. Our algorithm establishes a mapping from some of the optimizable parameters to the preassigned parameters of the relevant components. This mapping is updated iteratively until we reach the optimal solution.

abstract: Doctor of Philosophy (PhD)


title: Tube Row and Damping Parameter Effects on Tube-array Stability

contributor:
Weaver, D. S.
Mechanical Engineering

abstract:
Modern heat-exchangers are susceptible to damage due to the excessive tube vibrations caused by the shell side fluid flow. The present investigations seeks to further the understanding of flow induced vibrations due to fluid-elastic instability in tube arrays.

A low-speed wind-tunnel having 305 x 305 mm, working-section, was used to conduct the experiments. The tube-array was a parallel-triangle having a pitch/diameter = 1.375. The array was 18 rows deep with 5 tubes in each row. Nineteen elastically mounted movable tubes in the front of the array were especially designed so that natural frequency and damping could be controlled precisely over a wide range of values. Positions for as many as nine rows of fixed tubes in the front of the tube-array were available in order to facilitate studying the effect of tube-bundle size on tube response.

The experiments have indicated that the first tubes to become unstable in a particular tube-bundle are in the first few rows, and that the third and fourth rows are the critical ones. From the fluid dynamic damping-flow velocity results obtained for the array tested, it suggests the use of the static damping measured in still fluid for the estimate of the velocity for the onset of instability. For the first time a fluidelastic stability boundary as a function of the mass ratio has been determined experimentally for the array. This result along with the result obtained by Grover for the fluidelastic stability boundary as a function of the damping only, show that the mass ratio and the damping behave independently of each other, i.e., they should not be lumped together in the damping factor.

abstract: Master of Engineering (ME)


title: Description of anisotropic properties of trabecular bone

contributor:
Pietruszezak, S.
Webber, C. E.
Civil Engineering

subject:
Civil Engineering
Civil Engineering

abstract: This thesis presents a comprehensive approach to numerical modelling of human bone. Bone has been shown, in general, to be a heterogeneous material with orthotropic symmetry. The geometric arrangement of its porous micro-structure can be detected by high resolution tomographic imaging and then characterized by a 'fabric tensor.' This tensorial measure of material fabric can be correlated with mechanical properties and subsequently employed within numerical analyses of bone. In this work, the fabric tensor is incorporated into an elastic constitutive framework and a novel failure criterion for bone is proposed, which is seen as an important contribution to the numerical analysis of bone within the finite element (FE) methodology. The identification of fabric from micro-computed tomography (micro-CT) images of representative bone samples is achieved by a unified computational framework, described by a language independent pseudo-code. As a contribution to the constitutive representation of bone material, a new measure of fabric is defined and then identified using synthetic data of simple geometric shapes and micro-CT scans of human trabecular bone. The current potential for improvement in FE modelling of the mechanical behaviour of bone is illustrated through a discussion of bone fracture. The numerical analysis is an extension of the results presented in Pietruszczak et al. (1997, 1999) wherein a high resolution geometric model with heterogeneous distribution of orientation-dependent mechanical properties was employed. The use of the material model within a FE analysis is illustrated by a FE analysis pertaining to the prediction of fracture within a femur, under the simulated conditions of a fall to the hip. In particular, the distribution of damage within a femur is assessed under two porosity distributions, simulating a healthy and an aged bone.

abstract: Doctor of Philosophy (PhD)


title: The Great Lakes and human health: An interpretive environmental policy analysis

contributor:
Eyles, John D.
Geography

subject: Geography Geography

abstract: This thesis investigates the complexity of policy making in the Great Lakes. The International Joint Commission (IJC) is central to this investigation because of its binational position making recommendations to the Canadian and American governments under the 1972 Great Lakes Water Quality Agreement. The central tenet of this research is that policy text, as a social system, reflects the social context in which it was formed. This research uses an Advocacy Coalition Framework (ACF), frame analysis and semiotic analysis to present an interpretive policy analysis. Main data sources are key informant interviews and policy texts. An advocacy coalition framework is used to identify and structure the values within the policy subsystem. The frame analysis builds on the role of values in policy, as represented by the IJC Biennial Reports. The semiotic analysis is used to investigate the policy text at a more detailed level. Hence semiotics will bring to the forefront both 'meaning' and a 'validation of values' to the policy process (Yanow, 1996). Each of these three analyses are contextualized within a detailed description of the socio-political context to understand "policy-oriented learning" (Sabatier and Jenkins-Smith, 1997). This thesis three main findings are: values (in the form of ideologies, interests, and beliefs) play a critical role in the nature of policy making; the IJC plays a pivotal role, as policy-broker; and environmental policy change occurs through human health frames linking ecosystem and human health. This work makes substantive, methodological, and theoretical contributions. Substantively, it provides Great Lakes policy makers and researchers with an understanding of the parameters of environmental policy, specifically how human health is being used as a catalyst for policy change. Methodologically, it addresses policy discourse, communication, policy paradoxes and policy meaning. Theory contributions arise from conceptualizing language and policy text as a social system and through policy "framing", specifically how problems are framed and re-framed in place over time.

abstract: Doctor of Philosophy (PhD)


title: Heroes and their communities: A longitudinal study of four medieval romances

contributor:
Savage, Anne
English

subject:
English Language and Literature
English Language and Literature

abstract: This dissertation examines the principles that shape heroic behaviour in a selection of medieval texts that were directed towards a lay audience. These popular texts, written in the vernacular, both reflect and affirm the value systems of their intended audiences. I consider the nature of the societies they depict in terms of cohesiveness and stability, and then determine the role of the hero within such a structure. The struggles of the heroes, in turn, reveal the preoccupations and assumptions of their social milieu inside and outside of the text. In looking to romance for historical truths, this study reexamines the ways in which we read these texts. Moreover, my findings contribute to the study of individuality by exploring the ways in which medieval society negotiated the relationship between the desires of the individual and the needs of the community. I begin with an analysis of the Chanson de Roland , long read in light of its contributions to historical research, and, from there, apply the same methodology to four twelfth-century French romances: Partonopeu de Blois , Béroul's Roman de Tristan , Chrétien de Troyes' Lancelot ou le Chevalier de la Charrette , and Robert le Diable . Close readings of these narratives reveal that they all espouse a communal ethic that values honour, loyalty, and harmony. The next part of this dissertation explores fifteenth- and sixteenth-century English adaptations of the romances: Partonope of Blois , Sir Thomas Malory's Book of Sir Tristram de Lyones and the "Knight of the Cart" episode, and Robert the Devyll . The later romances depict a more fragmented society wherein characters are encouraged to pursue their own personal goals within the parameters established by fixed moral codes. By juxtaposing a synchronic study of the early romances with an analysis of their adaptations composed three hundred years later, this project demonstrates the transformation of a culture centered around the protection and promotion of the common good into a more modern ethos that recognizes the autonomy of the individual.

abstract: Doctor of Philosophy (PhD)


title: Cognitive processes in emotion recognition: A pet study of men, women and adults with autism

contributor:
Nahmias, Claude
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: We were interested in localizing the regionally specific brain responses which underlie the emotion processing strategies of men, women and a clinical population of individuals with emotion processing deficits: autism. In two studies we identified the brain regions involved in the recognition of emotion by measuring changes in regional cerebral blood flow (rCBF) using positron tomography. Study I asked adult men and women to perform face detection, identity matching and emotion matching tasks and compared the distribution of rCBF produced by each task. The recognition of facial emotion by males was associated with activation of the right inferior frontal cortex, whereas in females, activation of the frontal cortices bilaterally, and the right middle temporal and right inferior occipital gyri was identified. Between-group comparisons of the activations associated with facial emotion processing revealed that males showed greater right sided activation of medial frontal and superior occipital regions and less activation of the left inferior frontal gyrus, left fusiform gyrus and right amygdala than did women. Localization of function to these regions is consistent with other research results identifying greater distribution and less lateralization of cognitive functions in females than males. In our second study we presented cross-modal (auditory-visual) gender matching and emotion matching tasks to three groups of adults; men, women, and high functioning men with autism. Compared to the gender matching task, emotion matching was associated with activation of a left inferior frontal region in males, and the right superior temporal gyrus and right anterior cingulate gyrus in females. This pattern was similarly reflected in between-group comparisons, which identified significantly greater activations in a left inferior frontal region for males, and greater anterior cingulate and fusiform activations for females. These results identify sex differences in cross-modal emotion processing. Localization to these regions suggests that females placed greater relative processing emphasis on the auditory-prosodic and motivational qualities of the current experience, whereas males relied more on processes engaged in the construction of an integrated emotional experience and the regulation of responses. Cross-modal emotion matching by adults with autism was associated with activation of Broca's region, and bilateral anterior temporal poles. Between-group comparisons identified significantly greater activation of the right anterior temporal pole and anterior cingulate by the adults with autism, as compared to controls. These findings suggest that the adults with autism placed greater emphasis on processes involved in accessing perceptual knowledge to guide the categorization of emotional stimuli, verbal problem solving, directing attention toward cross-modal information sources and/or assessing the motivational content of stimuli.

abstract: Doctor of Philosophy (PhD)


title: Control relevant model identification with prior knowledge

contributor:
MacGregor, J.F.
Taylor, P.A.
Chemical Engineering

abstract: The use of prior or accumulated knowledge for the identification of multivariable models that will generally assure the stability of multivariable model based controller designs is investigated. The systems that are considered in this study are by and large linear, time invariant, ill-conditioned, and multi-input multi-output (MIMO) in nature. The effect of different types of prior information on controller stability is studied. It is shown that use of some types of prior knowledge may improve the model quality in terms of the stability of the resulting closed-loop system, while use of other types of prior knowledge may degrade the model quality. Prior knowledge that provides information about the low-gain direction of the process has the most significant effect on controller stability. Several issues associated with incorrect prior knowledge and the sensitivity of controller stability to such an error are also considered. This leads to checkable metrics that can be used by practitioners to evaluate the sensitivity of the controller to given prior knowledge before controller implementation. The issue of model maintenance (that is re-identification of existing models) that will result in improved controller stability in MIMO controllers is then addressed. Posterior knowledge about existing controller performance can be used to re-estimate models. Two novel controller designs result from this study: a multi-model style controller, and an adaptive style controller. Finally, issues regarding closed-loop identification of single-input single-output systems are considered. In particular, it is shown that the direct method of closed-loop identification results in an improved model quality compared to 2-step methods of closed-loop identification.

abstract: Doctor of Philosophy (PhD)


title: Identification of target genes of PEA3, an ETS family transcription factor

contributor:
Hassell, J.A.
Biochemistry

subject: Biochemistry Biochemistry

abstract: PEAS is a transcription factor of the ETS family, which has been implicated in mammalian development, tumorigenesis, and tumor progression. An attempt has been made to identify genes whose transcription is regulated by this factor in order to help elucidate its role in these processes. Cell lines, designated RP2, RP10 and RP11, were generated in which PEA3 overexpression can be induced at both the mRNA and protein levels. PEA3 overexpression in these cell lines is accompanied by activation of transcription of known PEA3 target genes such as MMP-9 and MMP-14 . Control cell lines, identical to these except for the lack of inducible PEA3 , show no such activation of PEA3 target genes under the same conditions. In order to identify PEA3 target genes mRNA isolated from RP 10 cells before and after induction of PEA3 overexpression was compared by Differential Display-Reverse Transcription PCR A number of mRNAs were identified that are coordinately upregulated with PEA3 . These include the mRNA that encodes Activated Leukocyte Cell Adhesion Molecule (ALCAM), which is a strong candidate PEA3 target. Activation of ALCAM transcription occurs in RP10 cells upon induction of PEA3 overexpression, but not in control cell lines. Similarly, activation of ALCAM transcription occurs in serum starved wild-type MEF cell lines upon induction of PEA3 expression by the addition of EGF, but not in PEA3 -null MEF cell lines under the same conditions. Finally, PEA3 is able to activate the expression of reporter genes downstream from fragments of the ALCAM promoter that contain consensus PEA3-binding sites.

abstract: Doctor of Philosophy (PhD)


title: From science to policy practice and public discourse: Claimsmaking and chlorinated drinking water

contributor:
Eyles, John
Geography

subject: Geography Geography

abstract: Since the rise of the environmental movement in the 1960s, public attention became focused on issues of ecosystem and human health. Since that time, there has been a growing public mistrust of industry, policymakers, and scientists. This research focuses on process-oriented issues in an area of scientific and regulatory 'uncertainty': chlorinated disinfection byproducts (CDBPs) and cancer outcomes. There are four objectives in this research. Scientific evidence regarding CDBPs and cancer is examined to explore how it has been constructed (objective 1). Further, the contesting of this evidence within the scientific community and its transformation to 'scientific fact' as 'authorities' is examined (objective 2). The impact these contested scientific authorities may have on the policymaking process in terms of setting guidelines, regulations, policies, and standards in both Canada and the United States is assessed (objective 3). Lastly, media presentations of scientific evidence as compared to framings by scientists, regulators, the chlorine industry, water utility representatives and environmental non-governmental organizations of the CDBP issue is investigated (objective 4). To address these objectives, this thesis adopts a mixed method approach by combining claimsmaking activities, narrative policy analysis, agenda-setting, and the use of language and metaphors to analyze the textual data. This thesis concludes that although the hegemony of science is challenged, the interpretation and use of scientific claims are increasingly important to establish authority and credibility on risk issues. Risk controversies are not going to disappear. These science-policy risk issues cannot be analyzed from a strict interpretation of 'science'. A 'social' lens must be brought in to understand the underlying political, social and cultural context of an issue. Risk controversies will not always take the same form in all places, and responses to these controversies must be sensitive to contextual differences. This thesis makes a number of substantive, methodological and theoretical contributions. Substantively, this research provides a detailed case study of a single uncertain and complex issue that links environment and health: CDBPs and cancer outcomes. The case study outlines how the issue has developed in two different regulatory environments (Health Canada and the US Environmental Protection Agency). Methodologically, this thesis incorporates multiple qualitative methods in its analysis of key informant interviews and written scientific, legal and policy documents. Theoretically, this research provides a conceptual model by which other environmental risk issues can be compared with respect to scientific uncertainty in the environmental health policy process.

abstract: Doctor of Philosophy (PhD)


title: The Canadian urban housebuilding industry: Firm size structure and production methods in Ontario, 1945--2000

contributor:
Harris, Richard S.
Geography and Geology

subject: Geography Geology Geography

abstract: The North American housebuilding industry is central to the production of urban space and the provision of housing. Yet surprisingly, housebuilding has received little scholarly attention in the housing, urban studies and industrial organisation literatures. Most of the major studies of the industry appeared in the early postwar years. These early studies interpreted the industry in terms of the preferred model of industrial organisation at the time, a model based on Fordist economies of scale, vertical integration and a highly segmented division of labour. Housebuilding's many small firms, labour intensive methods and subcontracting seemed underdeveloped, even backward, to observers. However, recent industrial restructuring has called into question the superiority of Fordist methods and permits a reinterpretation of housebuilding. This thesis provides such a reinterpretation based on a review of the organisation of housebuilding in North America since WWII and a case study of the industry in Ontario and its major urban region, Toronto. The case studies of Ontario and Toronto are based on quantitative and qualitative data sources and are combined with published and unpublished sources on housebuilding throughout North America since WWII. The principal sources used in this study are Canadian industry trade journals, a census of builders in the Province of Ontario from 1978 through 1998 provided by the Ontario New Home Warranty Program, and corporate interviews with a selection of builders in the Toronto region. As in North America since WWII, the case studies of Ontario and Toronto show that housebuilding remains a deconcentrated industry of small and transient firms. Entrepreneurs face few barriers to entry primarily because they can rely on a decentralised social system of production subcontracting. This permits a constant stream of new firms but also supplies many of the eventual exits as well. As such, housebuilding remains persistently deconcentrated while its firms experience constant turnover. On these grounds, criticisms of housebuilding by early observers are well-founded. Firm transience in an industry which supplies the most important commodity to the majority of North Americans continues to be a serious problem. However, interpretations of the small building company and its production methods as backwards were misplaced. Observers failed to appreciate the importance of the conditions of production and the market for new houses. The need to move production from site to site, to accommodate varied housing styles, weather, climate and market cyclicality all have consistently made production subcontracting an attractive method of operation. Indeed, many of the long-criticised features of housebuilding have come to be debated, and endorsed, in the literature on industrial restructuring in recent decades. For these reasons, housebuilding cannot be interpreted as backwards. This study joins a growing body of literature which argues against the notion of an optimal end state to industrial development. Industrial organisation may vary through time and across space. In remaining persistently deconcentrated by many small firms using extensive subcontracting methods, housebuilders merely represent efficient responses to the product and market conditions they face.

abstract: Doctor of Philosophy (PhD)


title: Neuromodulation of neocortical long-term potentiation in the adult, freely moving rat

contributor:
Racine, Ronald J.
Psychology

subject: Psychology Psychology

abstract: Correlated firing between adjacent neurons results in increased synaptic efficacy between synapses. This effect is called long-term potentiation (LTP) and is widely regarded as the mechanism underlying learning and memory because it is long-lasting and has been demonstrated in areas of the brain involved in information encoding and storage. Although definitive proof that LTP underlies learning and memory remains elusive, mounting evidence suggests that LTP, learning and memory are related and that LTP is a viable candidate for information storage. Understanding the nature of the relationship between LTP, learning and memory requires further investigation into the characteristics of LTP in the neocortex of the behaving rat. Neuromodulators have proven integral for successful learning. For this reason, their effect on LTP is of high interest. While neuromodulation of neocortical LTP has been studied in vitro , it has never before been investigated in the whole organism. This thesis explored the effects of cholinergic, noradrenergic and dopaminergic modulation on neocortical LTP induction in the behaving rat. In the cholinergic and noradrenergic experiments, significant group-by-session interactions were obtained in the early-component (monosynaptic) measures of LTP induction: Scopolamine, the cholinergic antagonist, blocked LTP while elenbuterol, a beta-noradrenergic agonist, enhanced LTP. The measure of LTP taken from the polysynaptic component resulted in significant group-by-session interactions for three modulatory manipulations. Pilocarpine, the cholinergic agonist, and apomorphine, the dopamine agonist, facilitated LTP. Clenbuterol and the beta-noradrenergic antagonist propranolol attenuated and tended toward attenuating LTP, respectively. Additionally, the neuroleptic haloperidol induced LTD. Taken together, these results provide more evidence for a relationship between UP and information processing. However, these results also highlight the complexity of neuromodulatory actions. Further research will aim to determine a more direct link between learning and memory by ascertaining dose-responses curves and applying them to behavioral tasks.

abstract: Doctor of Philosophy (PhD)


title: Determination of carbon black in urban air

contributor:
McCarry, B.E.
Chemistry

subject: Chemistry Chemistry

abstract: The City of Hamilton is one of the most heavily industrialized cities in Canada. In recent years, residents of communities in the east-end of Hamilton have complained about "black fallout" on their properties; this air particulate deposition takes the form of a fine, greasy black film that coats their houses, cars, etc. A carbon black production company has been suspected as the primary source of this black particulate, although there are other potential sources of black particulate, including emissions from two large steel industries, vehicular traffic and other sources. One of the major problems that has faced the Ministry of the Environment (MOE) in dealing with public complaints regarding "black fallout" has been the lack of an analytical procedure that would allow carbon black and other types of "black fallout" to be distinguished. My focus has been to develop the first analytical methodology to identify and quantify carbon black in ambient air. This approach to the determination of ambient levels of carbon black is based upon a sequential extraction methodology and the gas chromatography-mass spectrometric (GC-MS) quantification of an unusual polycyclic aromatic compound (PAC) I have identified on carbon blacks (thiacoronene) as a source tracer for carbon black. In an air monitoring study carried out from 1995 to 1998, I have been able to identify and quantify carbon black in ambient air samples collected downwind of a carbon black production plant, which varied from 0.01 to 1.43 μg carbon black/m3 of air. All concentrations of carbon black were well above the method detection limit of 0.004 μg/m3 with an uncertainty estimate of less than 5%. In the evaluation of sources of "black fallout" other than carbon black, I investigated a new source apportionment strategy based on a manganese-tin (Mn-Sn) metal index to differentiate levels of steel industry impacts in ambient air.

abstract: Doctor of Philosophy (PhD)


title: Single- and multiphoton studies of atomic negative ions: Electron affinities, threshold laws, and near-threshold structure

contributor:
Haugen, Harold K.
Physics

subject: Physics Physics

abstract: While neutral atoms and positively charged ions are bound in a Coulomb potential, the excess electron in an atomic negative ion is bound in an induced dipole potential (falling off as r-4 ). One consequence is that only a small number of states are bound in a negative ion, typically only the fine structure of one term, in contrast to the infinite number of states bound in a neutral or positively charged atomic system. The novel structure and binding potential of negative ions have attracted much interest on a fundamental level. In addition, negative ions play an important role in such areas as accelerator mass spectroscopy (AMS), atmospheric physics, and astrophysics. Despite considerable ongoing theoretical and experimental efforts, a number of atomic negative ion states remain poorly known or even completely unknown. Recently, tunable pulsed laser techniques have led the way in high precision measurements in atomic negative ions. This thesis presents results obtained with the tunable infrared laser source at McMaster University using single-photon threshold detachment and multiphoton resonant detachment spectroscopy, as well as non-resonant multiphoton threshold studies. Experiments investigating the structure of 13 elemental negative ions are detailed: Cs - , Cr- , Mo- , W - , Ru- , Os- , Ir - , Pt- , Cu- , Ag - , B- , Al- , and Bi - . Of particular note are the results of the first measurements on the negative ion of osmium which have provided the first and only known example of an atomic negative ion having both even and odd parity bound states. Strong continuum structures are also observed in Cs- , Os- , and W- for the first time, and appear as near-threshold Feshbach and shape resonances. Investigations of the behaviour of single- and multiphoton threshold laws are also presented. Specifically, single photon s -wave and p -wave threshold behaviours are measured to energies well above threshold and are compared to the models proposed by O'Malley and Farley. It is found that better results may be obtained if the two models are combined. Finally, two-photon experiments in Au- have demonstrated the extreme sensitivity of the near-threshold multiphoton detachment cross sections and the multiphoton threshold law to the polarisation state of the laser. These studies have led to the first observation of a Wigner d -wave law, and the technique is argued to have valuable applications to studies of negative ions which have structure lying near a photodetachment threshold.

abstract: Doctor of Philosophy (PhD)


title: The molecular basis of associative tolerance to opiates

contributor:
Siegel,  UniversityShepard
Psychology

subject: Psychology Psychology

abstract: The Pavlovian conditioning analysis of drug tolerance emphasizes that cues present at the time of drug administration become associated with drug-induced disturbances. These disturbances elicit unconditional responses that compensate for the pharmacological perturbation. The drug-compensatory responses eventually come to be elicited by drug-paired cues. These conditional compensatory responses (CCRS) mediate tolerance by counteracting the drug effect when the drug is administered in the presence of cues previously paired with the drug. Although there are many studies evaluating the molecular mechanisms underlying opiate drug tolerance, there are few experiments examining the role of Pavlovian conditioning in modulating the intracellular mechanisms that are hypothesized to mediate opiate tolerance. The results reported in Chapter 2 suggest that external predrug cues signalling morphine, and not simply chronic administration of morphine, are crucial in inducing morphine tolerance, striatal c-Fos, and AP-1 DNA binding. Besides external cues, internal cues also are important in mediating opiate tolerance and striatal c-Fos. The yoked-control experiments of Chapter 3 demonstrate that interoceptive cues inherent in self-administration are important for striatal c-Fos expression. Self-administering heroin (SA-H) animals exhibit less ataxia and more striatal c-Fos expression than their yoked partners (Y-H). The role of c-Fos is to activate other genes. The CCK2 receptor gene may be modulated by c-Fos and has been implicated in associative opiate tolerance. The in situ hybridization experiments reported in Chapter 4 were designed to investigate, in several brain areas, the RNA encoding the CCK2 receptor in SA-H, Y-H, and yoked-saline (Y-S) rats. Although no differences were found between the groups in the brain areas examined, the cDNA array experiments in Chapter 5 showed that the CCK2 receptor is up-regulated in the nucleus accumbens (NAcc ) of the SA-H rat compared to the Y-H rat. Furthermore, several other genes were also differentially expressed between SA-H and Y-H groups. The results of these experiments have helped narrow down those genes that may be involved in the associative opiate tolerance. Further investigation with more sophisticated gene screening techniques (e.g., gene chips) may elucidate the molecular mechanisms underlying the learned aspects of opiate tolerance.

abstract: Doctor of Philosophy (PhD)


title: Characterization of the catalytic mechanisms of two aminoglycoside phosphotransferases: APH(3')-IIIa from Enterococcus faecalis and APH(9)-Ia from Legionella pneumophila

contributor:
Wright,  Gerard D.
Biochemistry

subject: Biochemistry Biochemistry

abstract: While the aminoglycoside antibiotics continue to be useful chemotherapeutic agents, the appearance and dissemination of high level aminoglycoside resistant strains is a threat to the future clinical relevance of these antibiotics. Since there are only a limited number of alternative antibiotics, and resistance to all of these therapies has been observed, there is an urgent need to either introduce new classes of antibiotics or to 'rehabilitate' the ones currently employed. The development of drugs that inhibit the resistance mechanism is one method to 'rehabilitate' the usefulness of these antibiotics. As such, we are employing structure based drug design techniques for the development of inhibitors to several enzymatic aminoglycoside resistance mechanisms. A prerequisite for this method of drug design is a thorough knowledge of the catalytic mechanism of the enzyme, and as such I have characterized the regiospecificity and phosphoryl transfer mechanism of two aminoglycoside phosphotransferases: APH(3' )-IIIa and APH(9)-1a. From these studies, described herein, it is now known that the APH(3' )-IIIa enzyme catalyzes the direct transfer of the γ-phosphate of ATP to either the 3' -hydroxyl of 4,6-disubstituted aminoglycosides, or the 3' - and 5'' -hydroxyl of 4,5-disubstituted aminoglycosides, providing that both hydroxyl groups are present. It is also now known that APH(9)-la catalyzes the transfer of the γ-phosphate of ATP to the 9-hydroxyl of spectinomycin. Site directed mutagenesis, kinetic, metal, solvent isotope, and solvent viscosity studies of these two enzymes indicate that a dissociative-like transition state is employed, and that phosphate transfer occurs through a biomechanical process.

abstract: Doctor of Philosophy (PhD)


title: The direct detection of germenes in solution: The photochemistry of 1,1-diphenylgermetane, arylgermasilanes, and aryldigermanes

contributor:
Leigh, William J.
Chemistry

subject: Chemistry Chemistry

abstract: "Silenes" and "germenes" are molecules containing Si=C and Ge=C double bonds, respectively. Some of the reactions which involve the intermediacy of these species will be reviewed, as will some of the recent efforts to characterize transient silenes and germenes and investigate the mechanisms of their more common reactions. The first part of this thesis focuses on the generation and characterization of a germanium-carbon doubly bonded species in solution. Direct irradiation of 1,1-diphenylgermetane in hexane solution in the presence or absence of aliphatic alcohols leads to products consistent with the formation of 1,1-diphenylgermene as the primary photochemical product. Nanosecond laser flash photolysis of the germetane in hexane, acetonitrile and tetrahydrofuran gives rise to the formation of a transient, assignable to the germene on the basis of its second order decay kinetics, UV spectrum (λmax = 325-nm), and the fact that its lifetime is shortened by the addition of alcohols and acetic acid. The mechanism of silene and germene dimerization reactions was investigated using 1,1-diphenylsilacyclobutane and 1,1-diphenylgermetane as precursors to 1,1-diphenylsilene and 1,1-diphenylgermene respectively. 1,1,3,3-Tetraphenyl-1,3-disilacyclobutane, -1,3-digermacyclobutane, and 1,3-germasilacyclobutane have been synthesized by direct photolysis of hexane solutions of 1,1-diphenylsilacyclobutane, 1,1-diphenylgermetane, and a 1:1 mixture of the two. The photochemistry of 1,1,1-trimethyl-2,2,2-triphenylgermasilane (Ph 3 GeSiMe3 ), 2,2,2-trimethyl-1,1,1-triphenylgermasilane (Ph 3 SiGeMe3 ), and 1,1,1-trimethyl-2,2,2-triphenyldigermane (Ph 3 GeGeMe3 ) has been studied in hydrocarbon solution by steady state and laser flash photolysis methods. The results are compared to previously reported data for the homologous disilane Ph3 SiSiMe3 , whose photolysis under similar conditions results in the exclusive formation of a 1,3,5-(1-sila)hexatriene resulting from photochemical [1,3]-trialkylsilyl migration into one of the aromatic rings. (Abstract shortened by UMI.)

abstract: Doctor of Philosophy (PhD)


title: Commuter Bicycle Route Choice: Analysis Of Major Determinants And Safety Implications

contributor:
Hall, Fred L.
Baetz, Brian W.
Civil Engineering

subject:
Civil Engineering
Civil Engineering

abstract:
This research uses Geographic Information System (GIS) databases to manipulate the actual travel routes used by urban commuter cyclists to address issues related to bicycle route choice and bicycle safely.

Chapter 2 compares previously collected routes from Guelph to the shortest path routes. Most commuters divert little (0.4 km on average) and use major road routes. Although the cyclists tend to avoid grades, grade-separated railway crossings and high activity areas, they do not avoid high speed traffic or bridges. The cyclists use traffic signals especially for crossing major roadways and for turning. High-quality off-road paths are used infrequently, the lower quality ones even less.

Chapter 3 uses a logit model for route choice. The choice set determination is critical logic that checks alternative routes for duplication of attribute combinations is used. A multinomial logit model that exhibited independence from irrelevant alternatives is estimated. The model identifies route attributes similar to those described above. In addition, personal variables (age, gender, winter cycling) were found to be significant.

Chapter 4 describes the survey methodology used to collect two larger commuter bicycle route datasets in Toronto and Ottawa. Questionnaires containing a map for route collection as well as questions relating to cycling patterns and accident history were placed on cross-bars of parked bicycles. The return rate was 47% of the 6043 questionnaires.

The overall rates per 100,000 commuter kilometres of collisions, falls, injuries and major injuries were found to be 3.26, 9.51, 7.60 and 1.10 respectively (Chapter 5). These are approximately 10 times comparable rates for automobiles. The GIS was used to determine the distance in the regular route that was undertaken on-road, off-road or on sidewalks in the Ottawa study area. Collision rates on different infrastructure were not statistically different. However, injury and fall rates were highest on sidewalks (4 times that of roads) followed by off-road paths (1.6 times that of roads).

abstract: Doctor of Philosophy (PhD)


title: The Search for a Landfill Site in an Age of Uncertainty: The Role of Trust, Risk, and the Environment

contributor:
Matthews, D.R.
Sociology

subject: Sociology Sociology

abstract:
This study investigates the explanatory power of the theory of reflexive modernization proposed by Anthony Giddens and the theory of the risk society proposed by Ulrich Beck by empirically examining the interactions and issues raised in the innovative, open, and, inclusive Guelph Landfill Search Process (GLSP). The notions of risk, trust, and the environment are central elements of these theories, both of which propose that social change in the contemporary era has been stimulated by a process of confrontation with modem environmental risks. As such, we have examined the role that these three factors played in the GLSP.

It was observed that despite efforts by the City to inculcate feelings of trust and confidence in the search process, a lack of trust still remained. It is argued that this lack of confidence was not due purely to political factors, but was also due to the lack of trust in the institution of science and technology in general. It was found that the notion of risk was central to accounting for the adoption of such a perspective.

A central factor in the treatment of risk was the lay awareness of the technical uncertainties inherent to environmental impact science. In the context of the GLSP, this lay awareness pertained to issues related to the uncertainty in determining the character of the waste stream, the uncertainty about the hydrogeological features of the potential sites, and the awareness of the limitations of the technical methods and technologies used to detect, monitor, and contain the toxic leachate generated from the proposed landfill.

abstract: Doctor of Philosophy (PhD)