title: Historical Contex and the Forager/Farmer Frontier: Re-Interpreting the Nodwell Site

contributor:
Ramsden, Peter
Anthropology

subject: Anthropology Anthropology

abstract: This thesis examines the socio-economic transition from foraging to farming in Bruce County, Ontario which culminates with the appearance of the Nodwell village. the form (settlement pattern) and contents (material culture and subsistence remains) representative of a small-scale farming community, and was therefore distinct from the earlier forager habitations in the region. As recently as AD 1000 this region was occupied by mobile hunter-gatherers who followed an annual cycle, inhabiting numerous small sites, in nuclear family units. This strategy allowed the foragers of Bruce county to exploit various natural resources throughout the region during the course of the year. In contrast, the Nodwell village was occupied by a much more sedentary community of people, living in extended family groups, and producing domesticated crops. This transition occurred in a maximum of 350 years. Until recently, this transition was explained using a migration model which suggested that an intact horticultural community had migrated into Bruce county in the mid-fourteenth century and replaced the indigenous foragers. However, this model has become increasingly controversial. Primarily, the migration model over-simplifies the process of culture change by suggesting that culture change is short-term process, initiated from the outside. As a result, this model fails to explore adequately the complex historical, cultural, regional and ecological context in which this event occurred. Furthermore, by failing to situate the appearance of the Nodwell village into historical context this model was unable to negate the possibility that the transition from foraging to farming was initiated locally. In contrast, this dissertation re-evaluates the transition within a much broader historical and regional framework and demonstrates that the socio-economic transition from foraging to farming in Bruce county was a long-term process influenced by events occurring inernally, at the local level, and externally, through inter-cultural interaction. The process of change from foraging to farming will no doubt vary in other regions, but the historical approach used here provides a valuable explanatory framework which can be applied in other regions and will help to highlight the diversity of cultural behaviour in prehistory

abstract: Doctor of Philosophy (PhD)


title: Genetic Structure and Species Divergence Between Populations of Drosophila melanogaster and Its Sibling Species, Drosophila simulans

contributor:
Singh, Rama S.
Biology

subject: Biology Biology

abstract:
An essential element in the study of evolution is the knowledge about the origin and dynamics of genetic variation within and between populations, and between species. It is for this reason that the experimental population genetic studies always center around the characterization of genetic variation in natural populations. There are two opposing hypotheses about the nature of genetic variation and its role in evolution and speciation. The balanced hypothesis of genetic structure maintains that there is a large amount of genetic variation in natural populations and this variation is maintained by natural selection. The neutral hypothesis agrees with the balance hypothesis with respect to the amount of genetic variation but disagrees with respect to its role in evolution and speciation. The neutral hypothesis assumes that most of the variants are selectively neutral and their fate is governed by balance between neutral mutation and random genetic drift.

The melanoqaster subgroup of Drosophila, comprising of eight closely related species, has provided unique materials for studies of evolution. Presently, there is an increasing amount of interest in pursuing molecular evolutionary studies with species of this subgroup. In the past D. melanogaster and its sibling species, D. simulans have been extensively studied for their genetics, cytology, ecology and behaviour. These two sibling species have also been extensively studied for gene-enzyme variation. However, all previous studies have been sampled approximately between 10-30 gene loci and also these studies have emphasized mainly enzymes; very little work has been done with non-enzymatic proteins. The experimental approach taken in this thesis was to score structurally distinguishable gene products by gel electrophoresis within species, and compare the identity of variants at homologous gene loci between species. Over a hundred gene loci representing both enzymes and non-enzymatic proteins were sampled.

The natural populations of Drosophila melanogaster and Drosophila simulans were compared for their geographic structure and genic divergence. A total of 114 gene-protein loci were studied in four mainland (from Europe and Africa) and an island (Seychelle) populations of D. simulans and the results were compared with those obtained on the same set of homologous loci in fifteen worldwide populations of D. melanogaster (Singh and Rhomberg, 1987b). The main results are as follows: (1) D. melanogaster shows a significantly higher proportion of loci polymorphic than D. simulans (52% vs 39%, P < 0.05), (2) both species have similar mean heterozygosity and mean number of alleles per locus, (3) the two species share some highly polymorphic loci but they do not share loci that show high geographic differentiation, and (4) D. simulans shows significantly less geographic differentiation than D. melanogaster. The differences in geographic differentiation between the two species are limited to loci located on the X and second chromosomes; loci on the third chromosome show similar level of geographic differentiation in both species. Variation in niche-widths and/or genetic "strategies" of adaptation appear to be the main causes of differences in the genetic structure of these two species.

The comparison of genetic divergence between species produced the following results: (1) The polymorphic loci between D. melanogaster and D. simulans are significantly correlated, i.e., if a locus is polymorphic in one species, it is likely to be polymorphic in the other species also. (2) The various chromosomes show similar proportion of unique alleles within species but differ between species; D. melanogaster shows more unique alleles than D. simulans. (3) All chromosomes show similar proportions of shared alleles and similar genetic identities between species. (4) The loci that are diverged within species, are not the one that are diverged between species, suggesting no role of population structure to the species divergence. (5) While the present estimate of mean genetic distance, D = 0.179, between D. melanogaster and D. simulans is lower than previously reported values, the proportion of loci showing complete divergence between the two species is higher (10%) than all previously reported values.

These results suggest that possibly many genes are involved in species formation but the question remains whether the generalized enzyme loci sampled in the present as well as in past studies have much relevance to the problem of reproductive isolation and speciation. It is proposed that different kinds of genes or genetic systems may underlie adaptation and speciation, and that genetic and molecular analysis of reproductive characters (e.g. male-female genetalia and reproductive behaviours) would shed more light on the nature of genetic variation for speciation.

abstract: Doctor of Philosophy (PhD)


title: Thermodynamics of Microalloyed Austenites and Nonstoichiometric Carbides and Nitrides

contributor:
Kirkaldy, J.S.
Metallurgy

subject: Metallurgy Metallurgy

abstract:
The thermodynamics of Fe-Nb-C, Fe-Ti-C, Fe-Nb-N austenites and that of binary carbides and nitrides of Ti and Nb essential in the understanding of the precipitation behaviour in microalloyed steels has been investigated in this study. A dynamic gas equilibration technique has been used in the experimental investigation of the thermodynamics of ternary austenites and binary carbides of Ti and Nb. The results obtained in this study have been analyzed using the modified Wagner formalism for dilute ternary austenites and the sublattice - subregular model suggested by Hillert and Staffansson for the interstitial carbides and nitrides. The solubilities of NbC, TiC and NbN in austenite have been determined from the isoactivity measurements done in this study. The solubility minimum and the variation of solubility limits of carbides of Ti and Nb and the increase in carbon content at constant carbon activity have been quantitatively related to the ternary interaction parameter. The C-Nb, C-Ti and N-Nb interaction parameters have been determined. The dissolution free energies of Nb and Ti in fee Fe have been obtained from the analysis of the solubilities of NbC, NbN and TiC in their respective austenites.

Expressions describing the variation of the partial molar free energies of the components in the binary carbides and nitrides of transition metals have been obtained via statistical mechanical considerations. The pair interaction free energies involved in the statistical mechanical description of interstitial solutions have been related to the interaction parameters in the sublattice model. The carbon activity measurements in the NbCy and TiCy phases and the nitrogen activity measurements in the NbNy phase obtained in this study together with the data available in the literature have been analyzed to obtain the interaction parameters in the sublattice model. The limitations in applying the classical Wagner-Schottky model to highly nonstoichiometric compounds have been discussed. The necessary modifications to this classical model have been made by referring to the expressions obtained via the statistical mechanical approach.

The microalloyed ternary austenite - nonstoichiometric carbide equilibrium has been evaluated for the Fe-Nb-C and Fe-Ti-C systems. The effects due to solute interactions and the nonstoichiometry of the precipitate have been clarified. The solubility of TiN in Fe-Ti-N austenite has been calculated using the dissolution free energy of Ti evaluated in this study. Rational correlations between the ternary interaction parameters and the free energies of formation of carbides and nitrides have been established. Using this correlation an approximate value of the nitrogen-titanium interaction parameter has been evaluated.

abstract: Doctor of Philosophy (PhD)


title: The Role of the Theatre Audience: A Theory of Production and Reception

contributor:
Hutcheon, Linda
English

subject:
English Language and Literature
English Language and Literature

abstract: This thesis examines the reception of theatrical performances by their audience. Its starting points are (i) Brecht's dramatic theory and practice, and (ii) theories of reading. These indicate the main emphases of the thesis--theoretical approaches and performance practices, rather than the more usual recourse to dramatic texts. Beyond Brecht and reader-response criticism, other studies of viewing are explored. Both semiotics and post-structuralism have stimulated an intensity of interest in theatrical communication and such investigations provide an important impetus for my work. In suggesting a theory of reception in the theatre, I examine theatre's cultural status and the assumptions underlying what we recognize as the theatrical event. The selection of a particular performance is explored and from this, it is suggested that there is an inevitable, inextricable link between the productive and receptive processes. The theory then looks to more immediate aspects of the performance, including the theatre building (its geographic location, architectural style, etc.), the performance itself, and the post-performance rituals of theatre-going. The thesis shows how cultural systems, individual horizons of expectations and accepted theatrical conventions all activate the reception process and that all these are open to revision in the experience of performance. The description of an individual's experience of a particular performance is not, however, the object of this study. Instead the concern has been with an individual's culturally-constructed expectations which can be both met and/or challenged in a diverse range of contemporary theatrical performances.

abstract: Doctor of Philosophy (PhD)


title: Settlement, Trade and Social Ranking at Kitwanga, B.C

contributor:
Cannon, Aubrey
Anthropology

subject: Anthropology Anthropology

abstract: This thesis examines the influence of the indirect European contact upon Native social ranking and settlement systems at the Kitwanga Hill Fort and throughout the Upper Skeena Valley region of northern British Columbia during the Protohistoric Period (AD 1700-1830). Ethnographically, this is the territory of the Gitskan First Nation and falls within the Northwest Coast culture area. Diachronic spatial analyses of material excavated at Kitwanga and the distribution of archaeological sites in the region are integrated with historical documents and Native oral traditions relating to inter-group interaction and settlement. Native groups prior to direct European contact distributed to warfare, population movement and amalgamation, an increase in sedentism, particularly near trade routes, cultural borrowing and a growth and elaboration of socioeconomic differences between community members. I argue that these processes led to the late and widespread appearance on the Upper Skeena of the Northwest Coast culture pattern - particularly its settlement system and elaborate social differentiation. This thesis contributes to our understanding of the culture history of the Skeena, and the greater Northwest Coast culture area, which is often depicted as static durin late prehistoric and early historic times. It also contributes to the broader literature on culture contact by demonstrating that serious cultural changes can occur prior to direct European contact and that they are contingent upon the dynamics of indigenous cultures.

abstract: Doctor of Philosophy (PhD)


title: The Effects of Reading Context on Access to World Knowledge

contributor:
Levy, B.A.
Psychology

subject: Psychology Psychology

abstract:
Cognitive psychologists have started to explore how people use their world knowledge in order to accomplish a variety of tasks. The focus of the thesis research was to investigate how world knowledge is accessed during the reading comprehension process. It has been suggested (Barsalou, 1982) that very familiar knowledge is readily available regardless of what the reading context emphasizes, but that less frequently used knowledge is readily available only in contexts which emphasize that knowledge. Experiment I demonstrated that findings consistent with this point of view are obtained only when subjects know what concepts they will be tested on, otherwise, both familiar and less familiar knowledge are accessed more quickly in appropriate contexts than in other contexts.

Experiment 2 provided further support for the findings from Experiment I even though a different baseline and two different literary forms were used. Experiment 2 also demonstrated that the distinction between access to familiar and less familiar knowledge is a quantitative one rather than a qualitative one, as access to less familiar knowledge was speeded relatively more by an appropriate context than was access to very familiar knowledge. Experiment 3 confirmed that this distinction is robust, as it remained stable despite changes in task variables and subjects' strategies. Experiment 3 also demonstrated that access to both types of knowledge is hindered by inappropriate contexts but only when the degree of congruency between contexts and test items is increased so that it resembles the degree of congruency common to natural text.

The results of the research are important because they lead to the proposal of a principle by which fluent comprehension is achieved and by which new information is obtained from text. The studies also suggest that if experimental results are to be generalized to what normally happens during reading, it is of utmost importance that reading materials be presented in a manner which does not differ significantly from the natural reading situation.

abstract: Doctor of Philosophy (PhD)


title: A Unified, Integrated Approach to Generalized Circuit Optimization

contributor:
Bandler, John W.
Electrical Engineering

subject:
Electrical and Electronics
Electrical and Electronics

abstract:
This thesis offers a unified and integrated treatment of three essential aspects of computer-aided circuit design: effective use of the state-of-the-art optimization tools, efficient calculation of exact and approximate gradients, and adequate mathematical representation of the engineering problems.

The recent advances in gradient-based ℓp optimization are reviewed. The essence of the trust region Gauss-Newton method and the quasi-Newton solution to optimality equations is described. A new algorithm for linearly constrained one-sided ℓ₁ optimization is presented.

Efficient approaches to network sensitivity analysis are addressed. Useful formulas are derived for general multi-ports, especially two-ports. Novel proofs of an important result for lossless two-ports are given.

The basic formulations of nominal circuit optimization are introduced through a hierarchy of simulation models. Variables, error functions and ℓp objectives are identified. Optimization of multi-coupled cavity filters is described and illustrated by examples of elliptic, self-equalized and asymmetric designs. Large-scale optimization of multiplexers is also discussed.

Realistic consideration of tolerance and uncertainties is of prominent interest to circuit, especially integrated circuit designers. A multi-circuit approach to design centering, tolerancing, tuning and yield enhancement is presented. Techniques for statistical design are reviewed. A generalized ℓp centering algorithm is developed.

A novel approach to device modeling which utilizes multiple circuits and exploits the theoretical properties of the ℓp norm is described. It emphasizes the uniqueness and consistency of an equivalent circuit model. Practical applications are formulated and illustrated through industrial examples.

A new algorithm for optimization with integrated gradient approximations is offered. Implementations for the minimax and ℓp problems are shown. The efficiency and usefulness are demonstrated by a large variety of examples.

abstract: Doctor of Philosophy (PhD)


title: A Tool to Study Fusion-Evaporation Reactions

contributor:
Flibotte, S.
Physics

subject: Physics Physics

abstract: In recent experiments it has been observed that some discrete superdeformed bands in the mass A ~ 150 region are more strongly populated when mass-symmetric target-projectile combinations are used. It is proposed in this Thesis that these population differences result from a modification of the compound-nucleus angular-momentum distribution due to the presence of low-lying vibrational states in the target/projectile nuclei. Testing this hypothesis, for reactions leading to the population of super-deformed bands in the mass A ~ 150 region, is difficult because the fission process begins to compete with the formation of evaporation residues. This, however, is not a problem in the mass A ~ 130 region and a study of the nucleus ¹³⁵Nd was therefore undertaken with the reactions ⁷⁴Ge + ⁶⁴Ni and ²⁶MG + ¹¹²Cd. Angular-momentum distributions, when coupling to vibrational states was not considered, and excitation energies of the compound nucleus ¹³⁸Nd were closely matched for the two reactions. The ⁷⁴Ge-induced mass-symmetric reaction was found to preferentially populate high-spin states, including superdeformed states in ¹³⁵Nd. This is the first report of such an effect in the mass A ~ 130 region and the first time that such measurements have been made as a function of spin for individual superdeformed states. Statistical-model calculations were shown to be in agreement with the present observations provided coupled-channel effects were taken into account. To learn more about population mechanisms in the mass A ~ 150 region, a study of superdeformed band population at very high angular momenta was initiated with the reactions ⁷⁶Ge + ⁷⁶Ge and ²⁸Si + ¹²⁴Sn. Both reactions formed the compound nucleus ¹⁵²Gd at an excitation energy of 87 MeV. Relative to normally deformed states, the yrast superdeformed band in the residual nucleus ¹⁴⁷Gd was found to be population 4.6±0.2 times more strongly for the mass-symmetric reaction compared to the mass-asymmetric reaction. Such a large difference in the population was not expected. Furthermore, the superdeformed continuum feeding the yrast superdeformed states in ¹⁴⁷Gd was found to be at least 12 times stronger, relative to the population of the channel, for the mass-symmetric reaction. Statistical-model calculations, similar to those preformed in the mass A ~ 130 region study, could not reproduce the experimental results. Experiments like the one presented in this Thesis may provide valuable information about the fission barrier at very high angular momenta.

abstract: Doctor of Philosophy (PhD)


title: The Infrared Multiphoton Dissociation of Hexafluoroethane

contributor:
Smith, D.R.
Chemistry

subject: Chemistry Chemistry

abstract:
The infrared multiphoton dissociation (IRMPD) of "neat" hexafluoroethane has been investigated for the first time. The stable products of photolysis are CF₄, C₂F₄, C₃F₈ and C₄F₁₀. Product analysis involved tunable diode laser (TDL) and fourier transform infrared spectroscopy, as well as gas chromatography where applicable. The high sensitivity and resolution of the TDL allows for the measurement of the stable products CF₄ and C₂F₄ after irradiation by a single infrared laser pulse.

A high frequency modulation TDL technique has been developed to monitor the transient infrared absorptions produced by the IRMPD of various fluorocarbons. The technique was applied to the detection of CF₂ and CF₃ radicals produced by the IRMPD of known precursors. In the case of hexafluoroethane the TDL modulation technique was used to confirm that the primary dissociation pathway involves c-c bond session.

The role of added H₂, leading to elimination of CF₄ and increase of C₂F₄ as products, is clarified. Evidence for a second dissociation pathway producing C₂F₅ and a F atom is also presented. The understanding of the overall chemical mechanism of IRMPD of C₂F₆ and reaction of the intermediates formed has been considerably extended.

abstract: Doctor of Philosophy (PhD)


title: Mytilus edulis Shells as Environmental Recorders for Lead Contamination

contributor:
Risk, M.J.
Geology

subject: Geology Geology

abstract:
Marine contamination has been the object of a number of scientific studies, including the use of bivalves as biological monitors: This study investigates the feasibility of using Mytilus edulis shells as environmental recorders for lead contamination.

Samples of suspended particulate matter, surficial sediments and live mussels were collected from three locations: New Brunswick's northshore, in an industrialized region involved with the refining (Belledune Harbour) and stockpiling (Dalhousie Harbour) of lead/zinc ores; tidal flats near an urbanized area (Rimouski, Quebec), and a remote estuary (Negro Harbour, Nova Scotia). Organic and inorganic carbon fractions of the sediments were determined by combustion. Major and trace elements were determined by X-ray fluorescence spectrometry. Sequential extraction techniques were employed to study the partitioning of iron, manganese and lead among various sedimentary phases. Atomic absorption spectrometry was applied for the analyses of these three metals, as well as the lead obtained from the acid digests of the suspended particulate matter, tissue and shell components. A method was developed to separate the outer calcitic and inner aragonitic shell layers. Scanning electron microscopy was used to define the separation boundary between these two shell rayers. The number and thickness of the "annual layers" in the nacreous shell component were determined using acetate peels. The variation of lead contamination occurring during the mussels Iifetime was estimated by subsampling the oldest and most recently deposited nacre in the shells.

The total lead concentrations in the sediments collected from Belledune Harbour, Dalhousie Harbour, Rimouski and Negro Harbour were 941, 108, 21 and 29 μg/g, respectively. Similar amounts of lead were extracted from the sediments except at Negro Harbour where only 13 μg/g lead was extracted. The highest and lowest tissue (shell) lead levels were detected in mussels collected from near Belledune Harbour and Negro Harbour, 456 (49) and 2 (<0.5) μg/g, respectively, whereas mussels sampled from Dalhousie Harbour and Rimouski contained comparable amounts of lead, 9 (0.8) μg/g. The tissue and shell lead concentrations were not influenced by mussel size. The lead levels in the nacreous shell layers were correlated (r:0.966) with those in the tissues, and were best related to the lead obtained from the second fraction of the sequential extraction, lead bound to carbonates. The higher phosphorus concentration at one station in Belledune Harbour, B3 (1.33%), may have suppressed the uptake of lead in the mussels at this site, 150 μg/g tissue Pb and 13 μg/g shell Pb. Significant changes of lead concentrations within the nacreous shells of mussels collected near Belledune Harbour (19 and 45 μg/g), reflected variations of lead levels in sediments.

This study demonstrates that Mytilus edulis-shells, reflect the biological uptake of lead during the lifespan of the organisms, and serve as environmental lead recorders.

abstract: Doctor of Philosophy (PhD)


title: Growing up among the Looms: The Growth and Nutrition of Children Living in a Peri-Urban Environment in Kathmandu, Nepal

contributor:
Herring, D. Ann
Anthropology

subject: Anthropology Anthropology

abstract: This study examines the nutritional and health status of children under five years of age whose mothers are working as weavers and spinners in the carpet-making industry in Kathmandu, Nepal. The research design samples both carpet-making factories and households where the predominant mode of income generation for women is spinning wool at home for carpet manufacturers. A biocultural approach that combines quantitative and qualitative research methods - anthropometry, questionnaires and semi-structured interviews - is used to investigate the social and biological contexts of children's health and nutritional status. Although low weight-for-weight, or acute wasting, is not evident among the 283 children in this study, they are found to be moderately to severely growth stunted with poor upper arm musculature, relative to international growth standards. Similar to other children in Nepal, there is some weight loss evident in the hot and monsoon seasons compared to the cold season. Despite the fact that mothers are engaged in wage labour, both factory and home workers in this sample breastfeed for the first two to three years postpartum almost universally and therefore maternal lactation practices are not implicated in growth retardation. A synergistic interaction between low quality and quantity of weaning foods and an extremely high load of infectious disease - particularly diarrheal illnesses and gastrointestinal parasites - implicated in growth retardation. Some of the more traditional foci of child health studies such as maternal care and socio-economic status of the household are found to have little explanatory power in this research. An investigation of the peri-urban environment - the newly settled and marginal district that borders that city - points to the operation of macro environmental factors in debilitating the health of the children in this study. It is argued that an environmental health perspective constitutes the most appropriate framework for interpreting growth faltering among these children and that the lack of infrastructure in this peri-urban environment leads to poor sanitary conditions and high rates of chronic childhood infections. The research calls for increased anthropological attention to the environmental conditions that facilitate high pathogen loads among children, an area of inquiry that is often under-investigated relative to nutritional issues per se.

abstract: Doctor of Philosophy (PhD)


title: Wordsworth's Theory of the Child's Unconscious Response to Nature in The Prelude

contributor:
Coldwell, J.
English

abstract:
Many critics have emphasized the fact that Wordsworth, as a child, is "unconscious" of his communion with nature. Few, however, attempt to explore the details of this unconscious attitude. Many of those who do study the relationship in depth equate this unconsciousness with passivity.

Wordsworth is "unconscious" in two senses of the word. Firstly, he is simply unaware of the fact that he is communing with nature, and that nature is influencing and affecting him in a profound manner. Secondly, he does not realize the part he plays in the relationship. Critics have pointed out the projection of Wordsworth's fear and guilt, of which he is unaware, in the boat-stealing episode, and I believe that this unconscious participation extends to the other childhood incidents described in Books I and II of The Prelude. Thus Wordsworth, as a child, is not passive.

This unconscious attitude continues throughout childhood and boyhood until the years of youth, at which time a significant change in Wordsworth's perception takes place. In this thesis I will study this unconscious aspect of the Wordsworth's relationship with nature and the important modifications which occur during youth.

abstract: Master of Arts (MA)


title: Beyond Spectacle: Eliza Haywood's Female Spectators

contributor:
Walmsley, P.
English

abstract: Through an examination of scenarios of seeing and being seen in selected texts of Eliza Haywood, the dissertation examines how forms of power are conducted through the operations of sight and seeing, with the specific tasks of theorizing forms of agency for women that would allow them to evade a dominating, often voyeuristic, male gaze. Eighteenth-century texts that foreground ocular experience, including Addison and Steele's Spectator, Johnson's Rambler and Le Sage's Le Diable Boiteux, historicize and contextualize the discussion. Lacan's theory of the gaze, whereby subjectivity is conferred within the visual field, informs the argument, as do theories of the female gaze developed by feminist film critics. Haywood explored strategies which undermine the conventional male spectator/female spectacle structure of looking, and demonstrated that by manoeuvring within the limitations imposed by their role as objects of sight, women can exercise forms of power. Ultimately the thesis argues that Haywood's own strategy as an author involved the direct appropriation of the spectator position as a means of establishing discursive authority.

abstract: Doctor of Philosophy (PhD)


title: Selective Attention, Negative Priming, and Hyperactivity: Investigating the 'AD' in ADHD

contributor:
Milliken, B.
Psychology

subject: Psychology Psychology

abstract: Negative priming producing by hyperactice and non-hyperactive boys was measured in two experiments. The use of the negative priming paradigm allowed for the interpretation of hyperactive/non-hyperactive differences in performance within the framework of previously developed process models. Previous studies of hyperactivity have relied on measures of distractibility as an index of selective attention, and have lacked a method for exploring possible deficits in underlying attention mechanisms. Significantly reduced negative priming produced by a school-based sample of hyperactive boys as compared to age-matched non-hyperactive peers was found across spatial of hyperactive boys as compared to age-matched non-hyperactive peers was found across spatial localization and letter identification tasks in Experiment 1. In Experiment 2, negative priming produced in a letter identification task by a clinic-based sample of boys diagnosed with Attention-deficit Hyperactivity Disorder (ADHD) was compared to that produced by non-hyperactive controls. Combined data from the letter identification tasks in Experiments 1 and 2 provided sufficient power to detect a between-group difference statistically. In an effort to account for the relatively small and variable nature of the hyperactive/non-hyperactive differences in negative priming that were found, the influence of hyperactive subgroups was examined and the theoretical interpretation of negative priming effects was reconsidered within the frameworks of three current process models. The findings of this study are particularly significant with regard to the reinforcement of inattention as a key deficit in hyperactivity.

abstract: Doctor of Philosophy (PhD)


title: G PROTEINS AND PARKINSON'S DISEASE: THE ROLE OF SIGNAL TRANSUCING G PROTEINS IN MEDIATING DOPAMINE RECEPTOR SUPERSENSITIVITY IN PARKINSON'S DISEASE

contributor:
Mishra, Ram K.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: There is growing evidence that factors other than cell-surface recetors are involved in regulating the sensitivity of cells to external signals. In particular, G proteins have been implicated in the increased sensitivity of numerous receptor systems under a variety of conditions (Mishra et al., 1997). The goal of this research project was to determine the role of G proteins in mediating dopamine receptor supersensitivity in Parkinson's disease. Prelimary studies of G protein levels in human post-mortem brain tissue proved inconclusive, due to the limited availability and variability of tissue samples. Subsequent studies in the 6-hydroxydopamine (6-OHDA) rat lesion model of Parkinson's disease revealed that stimulatory G protein levels are persistently elevated following denervation (Marcotte et al., 1994). These G proteins are presumably coupled to dopamine D₁ receptors, which show clear evidence of supersensitivity despite apparently normal receptor levels. This result supports the hypothesis that G proteins are involved in the maintenance of dopamine receptor supersensitivity (Marcotte and Mishra, 1997). Stimulatory G proteins acutely following MPTP mouse model, with decreased stimulatory G proteins acutely following MPTP treatment, and increased stimulatory G proteins after long-term recovery (Marcotte et al., 1998a). Although the significance of these findings is unclear, they provide additional support for the hypothesis that G proteins are modulated in response to dopaminergic denervation. Attempts to measure functional changes in stimulatory G protein activity in the rat striatum proved unsuccessful, consistent with the available literature. Specifically, neither the GTPase nor a specific GTP binding assay was able to consistently detect stimulatory G protein activity following dopamine D₁ receptor stimulation. To provide direct evidence for the role of Golf in mediating dopamine receptor supersensitivity, Golf antisense oligonucleotides were administered to 6-OHDA lesioned rats. Intrastriatal infusion of Gold antisense, but not control sense oligonucleotides, specifically reduced apomorphine-induced rotational behaviour and Gold levels. The effects of Golf antisense infusion were at least partially reversible, supporting a specific antisense mechanism of action. However, one of the control oligonucleotides, Golf missense, consistently reduced rotational behaviour and G protein levels in a non-specific fashion. This effect was dose- and sequence-dependent, and may be due to a non-specific binding to other nucleotides or proteins (Marcotte and Mishra, 1998). Taken together, these studies support the hypothesis that stimulatory G proteins are involved in mediating dopamine D₁ receptor supersensitivity. Further characterization of the effects of in vivo antisense oligonucleotides may provide more definitive conclusions regarding the role of G proteins in mediating this phenomenon.

abstract: Doctor of Philosophy (PhD)


title: Interaction of Thrombin with Prothrombin Fragment 2, Heparin Cofactor II, and Fibrin

contributor:
Weitz, Jeffrey I.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: Thrombin is a multifunctional serine protease that plays a central role in hemostasis. Unlike related serine proteases of the hemostatic system, thrombin is unique in that is has both procoagulant and anticoagulant activities. Structural features defined by X-ray crystallographic studies of thrombin provide a molecular basis for the enzyme's specificity. These features include the active site cleft and two anion-binding electropositive exosites located on opposite poles of the thrombin molecule. What is less evident from crystallographic studies is the thrombin's flexibility and its capacity to undergo conformational changes upon ligand binding to the exosites. These studies were undertaken to explore different but interrelated aspects of thrombin regulation. The first goal of this thesis was to determine how prothrombin fragment 2 (F2), a prothrombin activation fragment, binds to thrombin and modulates its activity. Cocrystallographic studies have shown that the interaction F2 with thrombin involves the formation of salt bridges between the kringle inner loop of F2 and anion-binding exosite II of thrombin. When F2 binds to thrombin, it has been shown to evoke conformational changes at the active site and at exosite I of the enzyme. Using plasma, recombinant, and synthetic F2 peptides (F2, rF2, and sF2, respectively) we have further localized the thrombin binding domain on F2. F2, rF2(1-116), rF2(55-116), and sF2(63-116), all of which contain the kringle inner loop (residues 64-93) and the acidic C-terminal connecting peptide (residues 94-116), bind to thrombin-agarose. In contrast, analogues of the kringle inner loop, sF2(63-90), or the C-terminal connecting peptide, sF2(92-116), do not bind. Thus, contrary to predictions from the crystal structure, the C-terminal connecting peptide as well as the kringle inner loop are involved in the interaction of F2 with thrombin. F2 and sF2(63-116) bind saturably to fluorescently labelled-active-site-blocked-thrombin with Kd values of 4.1 and 51.3 μM, respectively. The affinity of sF2(63-116) for thrombin increases about 5-fold (kd=10 μM) when Val at position 78 is substituted with Glu. F2 and sF2(63-116) bind to exosite II on thrombin because both reduce the heparin-caalyzed rate of thrombin inhibition by antithrombin - 4-fold. In contrast, only F2 slows the uncatalyzed rate of thrombin inactivation by antithrombin. Like F2, sF2(63-116) induces allosteric changes in the active site and exosite I of thrombin because it alters the rates of thrombin-mediated hydrolysis of chromogenic substrates and displaces fluorescently-labelled hirudin₅₄₋₆₅ from active-site-blocked thrombin, respectively. Both peptides also prolong the thrombin clotting time of fibrinogen in a concentration-dependent fashion reflecting their effects on the active site and/or exosite I. The different functional changes evoked by F2 and sF2(63-116) likely reflect additional contacts if F2 relative t the smaller sF2(63-116) and suggest that ligand binding to various subdomainds within exosite II may have different effects on thrombin function. The important implication of these findings is that distinct allosteric effects evoked by ligand binding to subdomainds of exosites may contribute to the diversity of thrombin function at the molecular level. The activity of thrombin is also regulated by blood-borne protease inhibitors. The second goal of this work was to gain insight into the mechanism by which thrombin is inactivated by heparin cofactor II (HCII), a serine protease inhibitor (serpin) in plasma that selectively inhibits thrombin in a reaction that is accelerated ≥1000-fold by glycosaminoglycans (GAGs) such as dermatan sulfate (DS) and heparin. Current thinking is that GAG binding to HCII disrupts ionic bonds between the amino-terminal acidic domain and the GAG-binding domain of HCII, thereby permitting the acidic domain to interact with exosite I on the thrombin. Based on this allosteric activation model, we predicted that substitution of basic residues in the GAG-binding domain of HCII with neutral ones would mimic the catalytic effect of GAGs. Compared with wild-type recombinant HCII expressed in BHK cells (wt rHCII), mutation of Arg¹⁸⁴, Lys¹⁸⁵, Arg¹⁹², Arg¹⁹³ (Mut C) or Arg¹⁸⁴, Lys¹⁸⁵, Arg¹⁸⁹, Arg¹⁹², Arg¹⁹³ (Mut D) reduced the affinity for heparin-Sepharose and increased the uncatalyzed rate of thrombin inactivation ~130-fold (from 4.6 x 10⁴ M⁻¹ min⁻¹ to 6.2 x 10⁶ and 6.0 x 10⁶ M⁻¹ min ⁻¹, respectively). Furthermore, unlike wt rHCII or plasma-derived HCII (pHCII), neither heparin nor dermatan sulfate increased the rate of thrombin inhibition by Mut C or Mut D. The increased basal rate of thrombin inhibition by these mutants reflects displacement of their amino-terminal acidic domainds because (a) they inhibit ϒ-thrombin at a 65-fold slower rate than α-thrombin, (b) the exosite 1-binding fragment hirudin-(54-65) decreases the rate of thrombin inhibition, and (c) deletion of the amino-terminal acidic domain (-del74) of Mut D reduces the rate of thrombin inhibition ~ 100-fold. To determine whether GAG-mediated bridging of thrombin to HCII contributes to accelerated thrombin inhibition, we compared the catalytic effects of longer heparin or dermatan sulfate chains with those of shorter chains. Heparin chains comprised of 30 or more saccharide units produced an ~5-fold greater increase in the rate of thrombin inhibition by pHCII, wt rHCII, and wt-del74 than heparin chains comprised of 20 or fewer saccharide units. In contrast, dermatan sulfate and a low molecular weight fragment of dermatan sulfate stimulated thrombin inhibition by pHCII and wt rHCII to the same extent, and neither agent affected the rate of thrombin inhibition by wt-del74. Our findings support the concept that heparin and dermatan sulfate activate HCII by releasing the acidic amino-terminal domain from intramolecular connections with the GAG-binding domain. Since both GAGs produce ≥ 1000-fold increase in the rate of thrombin inhibition by HCII, our observation that only heparin serves as a template raises the possibility that dermatan sulfate induces more extensive allosteric changes than heparin. In addition to regulation by serpins, thrombin function is also modulated by its incorporation into forming thrombi. Despite being catalytically active, fibrin-bound thrombin is protected from inactivation by inhibitors, notably antithrombin (AT)/heparin. The resistance of fibrin-bound thrombin to inactivation by AT is thought to reflect formation of a productive ternary thrombin-fibrin-heparin complex in which thrombin is protected from inactivation by AT. The anchoring of thrombin in a productive ternary complex is mediated by thrombin's exosites, fibrin via exosites I and heparin via exosite II. It has been proposed that productive ternary complex assembly is dependent on binary interactions between thrombin-heparin, thrombin-fibrin, and heparin-fibrin. Unlike heparin, DS inhibitors soluble and fibrin-bound thrombin equally well, however the explanation for this phenomenon is unclear. The third goal of this work was to determine why fibrin-bound thrombin is susceptible to inactivation by the HCII/DS complex but not by the AT/heparin complex. The results of this study indicate that, unlike heparin, DS does not promote the formation of a productive ternary thrombin-fibrin-DS complex. This concept is supported by three lines of evidence. First, in the presence of fibrin monomer (Fm), thrombin is protected from inhibition by HCII/heparin, but not by HCII/DS as quantified by protease inhibition assays under pseudo first-order conditions. Second, DS does not promote the binding of radiolabeled active site-blocked thrombin (¹²⁵I-FPR-thrombin) to fibrin. In contrast, heparin augments ¹²⁵I-FPR-thrombin binding to fibrin in a concentration-dependent manner. Third, DS does not interact with fibrin and binds to thrombin with a 22-fold lower affinity than heparin (Kd values of 2.6 μM and 117 nM, respectively). These results reveal that, although exosite I and exosite II of thrombin can be ligated by fibrin and DS, respectively, productive ternary complex does not occur because DS is unable to bridge thrombin to fibrin. These findings indicate that all three binary interactions are essential for productive ternary complex formation. We also examined the protective effect of the thrombin-fibrin-heparin complex on thrombin inhibition by Mut D. Whereas Fm alone has little effect on the uncatalyzed rate of thrombin inhibition by Mut D, addition of heparin decreases the rate of thrombin inhibition by Mut D ~ 30 fold (from 6.0 x 10⁶ M⁻¹ min⁻¹ to 2.1 M⁻¹ min⁻¹). Furthermore, in the presence of Fm, heparin causes a dose-dependent decrease in the DS-catalyzed rate of thrombin inhibition by HCII. These observations reveal that the protective effect of heparin results from the anchorin of thrombin in a productive thrombin-fibrin-heparin complex in which exosite I is inaccessible to the amino-terminus of HCII. Collectively, these studies illustrate different modes of regulating thrombin function, all of which are intricately interrelated. The remarkable diversity of thrombin activity allows thrombin to serve multiple functions in highly controlled processes in hemostasis.

abstract: Doctor of Philosophy (PhD)


title: The Geography of the British Northern Interior Frontier of Defence During the Haldimand Revolutionary War Administration of Quebec, 1778-1782

contributor:
Burghardt, A. F.
Geography

subject: Geography Geography

abstract: This study examines the geography of the British Interior Frontier of Defence, between the colony of Quebec and the rebel colonies of America, during the Revolutionary War administration of Sir Frederick Haldimand (1778-1782). The study has three aims: firstly, to map the location of the frontier, secondly, to identify its essential characteristics and thirdly, to describe its defence administration. A reconstruction approach has been taken in order to uncover the geographical elements of the frontier as perceived by eighteenth-century administrators. To a large extent the identification of the interior frontier of defence was made from primary source material, chiefly the Haldimand Papers and historic maps. One research problem was the matching of primary source locations with modern maps and field identification. The defence frontier, unlike the pre-conquest frontier of Eccles, was a frontier of the colony of Quebec, which exhibited several characteristics. Firstly, it was a zone of tension as with marchland, being organized on a semi-permanent military basis. Secondly, it was sparsely settled thus limiting the amount of provisions that could be generated for defensive activities. Thirdly, its military government was imposed from outside, giving rise not only to distance decay and the diminishment of central power, but also to reactions from frontier settlers who wished to govern themselves. Fourthly, the degree of administrative control necessary to administer frontier defence precluded the operation of lawlessness and anarchy, postulated by Turner for his frontier. Fifthly, the frontier exhibited both integrating and separating characteristics, depending of the volatile political allegiances within it. Sixthly, the frontier did no exhibit a well-defined line of confrontation, although there was a general accordance with colonial frontier forts and settlements, with arteries of travel, and with the Upper Post administrative centers. The British imperial administration of the frontier was based on two major policy directives: the Royal Proclamation of 1763 and the Quebec Act of 1774. However, due to the exigencies of war, the Quebec Act was never fully instituted along the Upper Post administrative chain and defence frontier. The defence frontier was governed by the Upper Posts of Niagara, Detroit and Michilimackinac, with Quebec and Montreal as the command headquarters for the colony as a whole. It was administered chiefly through the Military and Indian Departments, which instituted policy for frontier defence. Defence activities, chiefly campaigns, raids, and scouts, were concentrated on the Mohawk Valley, the Delaware and Susquehanna Rivers, Fort Pitt and the Allegheny River, the Ohio and its tributaries and the Illinois. Due to the problem provisioning military activities during the War of Revolution the geography of the interior frontier of defence was largely delimited by provisioning sites such as forts, settlements, forge and mill sites and agricultural areas.

abstract: Doctor of Philosophy (PhD)


title: A Numerical Study of Jet-to-Jet Impingment in a Mixing Head

contributor:
Wood, P.E.
Hrymak, A.N.
Chemical Engineering

subject:
Chemical Engineering
Chemical Engineering

abstract:
A numerical method has been developed to model the jet-to-jet impingement in a mixing head. The governing equations are discretized in non-orthogonal curvilinear coordinates and higher-order upwinding methods are used for convection term discretization. Several problems with known solutions are used to test accuracy of the method. The results show that the method can predict the flow fields at moderate and high Reynolds numbers accurately.

The opposed jet flow field is used by the reaction injection moulding mixhead to mix pre-polymers. The stready state flow field exists at Reynolds numbers below 90 and unsteady state exists at Reynolds numbers above 90. The results of numerical simulations show that at the Reynolds number 50, the flow field is symmetrical and rotating ring vortices are formed around the impingement point. Symmetry breaks down as the Reynolds number is raised. Time integration showed that the flow field oscillates at Reynolds numbers above 100 and multiple frequencies exist at the Reynolds number of 125. The results are consistent with experimental results.

In the last chapter, the dynamical system theory is used to examine the opposed jet flow field. The stagnation point is a hyperbolic point of a dynamical system and can promote mixing. The elliptic points which exist at the core of vortices hinder mixing. The (D:D)1/2 field was evaluated and confirmed the results of the dynamical system theory. The area surrounding the hyperbolic point had highest (D:D)1/2 values indicating that the flow field can stretch more efficiently. A flow pattern which consists of multiple hyperbolic points is proposed as an alternate design for the mixhead.

abstract: Doctor of Philosophy (PhD)


title: Linear Array Structures for Direction of Arrival Estimation

contributor:
Haykin, S.
Electrical and Computer Engineering

subject:
Electrical and Computer Engineering
Electrical and Computer Engineering

abstract:
The impact of the array geometry for linear arrays on the estimation of the direction of arrival of incident plane waves is examined in this thesis. The fundamental result is the establishment of the conditions under which array structures, different from uniformly spaced, may provide improved accuracy or reliability in these estimates. We are primarily concerned with the use of high accuracy estimators, attempting to obtain accuracies well within the classical beamwidth of the array.

Several different criteria for designing thinned array structures are described, with the principal emphasis on redundancy based designs. For a single plane wave incident on the array, the Weiss-Weinstein bound, which is an estimator independent bound, is applied to a variety of array structures and indicates that the thinned arrays will yield greater accuracy, provided the SNR is sufficiently large. The bound allows us to investigate the effects of a priori information on the estimation performance of the different structures considered.

Maximum likelihood estimation is applied to the identical problem and similar tradeoffs are observed. We propose the concept of outlier probability as a measure for discriminating between array structures and provide models for characterization. Certain algorithms in the literature for the design of nonuniform arrays are shown to be poor under these measures.

The impact of array structure in a multipath environment consisting a target with a strong specular reflection is illustrated using exact maximum likelihood estimation. It is shown that the most significant gains to be made for thinned arrays occur when the multipath is such that target and image are well within a beamwidth of the array. Under these conditions, it is found that the nonuniform arrays often outperform uniform arrays consisting of many more elements for all values of SNR and phase differences between the two plane waves.

An experimental, 32-element array was constructed and brought into the field in order to gather multipath data over water, in a real world environment. For the very closely spaced target and image of this experiment, the nonuniform arrays outperform uniform arrays consisting of even twice as many elements.

abstract: Doctor of Philosophy (PhD)


title: Middle and Upper Keweenawan Siliciclastics of the Lake Superior Basin

contributor:
Middleton, G.V.
Geology

subject: Geology Geology

abstract:
Middle and Upper Keweenawan sediments of the Lake Superior Basin were deposited by braided streams on large, gently sloping, fluvially-dominated alluvial fans.

The conglomeratic facies association (upper fan deposits) dominates the Keweenawan succession. The conglomerates are coarse and poorly sorted with fabrics between cIast-supported and (sandy) matrix-supported. Sorting is so poor that the clast-matrix division is arbitrary, so the term c-m supported (from clast and matrix supported) is used. The conglomerates were deposited on longitudinal bars by simultaneous deposition of sand, granules, pebbles, cobbles and boulders. This style of deposition reflects high sediment yields and flashy stream behaviour resulting from the Iack of terrestrial plants. Intercalated sandy lenses with low-angle cross-stratification were deposited in channels by antidunes or poorly developed dunes.

Conglomerates of the conglomerate-sandstone facies association (mid-fan) are better sorted and imbricated and show some planar cross-stratification, indicating that longitudinal and transverse bars were present. Intercalated sandstones are trough cross-stratified and fIat-bedded.

The sandy facies association (lower fan) comprises trough cross-stratified sandstones (channeI deposits) and flat bedded and rippled sandstones (bar-top deposits).

The abundance of trough cross-stratified sandstones implies that slopes on the Keweenawan fans were lower than those indicated by alluvial fan facies models. More attention shouId be paid to large, gently sloping, fluviaIly-dominated alluvial fans.

Abrupt transitions from proximal fan conglomerates to lacustrine sediments reflect volcanic damming. More gradual and poorly defined vertical facies transitions resulted from changes in tectonism.

The Keweenawan streams were ephemeraI, and desiccation features are abundant. These conditions enabled the development of fields of small transverse aeolian dunes, giving rise to large-scale cross-stratified well sorted sandstones. Aeolian palaeocurrents may indicate topographically constrained palaeo-trade winds.

abstract: Doctor of Philosophy (PhD)


title: A Study of Uranium in Ground Water Around Greyhawk Mine, Bancroft, Ontario

contributor:
Schwarcz, Henry P.
Ford, Derek C.
Geology

subject: Geology Geology

abstract:
The mining operations at the Greyhawk Uranium Mike began in 1956 and were discontinued in 1959. As a consequence of the mining opeartions, a waste rock pile (pegmatite granite and gabbro) was developed at the site. These rocks have subsequently undergone weathering processes and consequently introduced leachate into the aquifer.

The uranium content and uranium isotope ratio (²³⁴U/²³⁸U) of the Greyhawk ground waters were measured utilising the analytical methods of isotope dilution and alpha- particle spectrometry. Uranium contents range from about 1.2 to as high as 380 ppb. Most samples at deep sampling points (>7m) are usually anomalously high. This suggests that a plume of uranium-rich water possibly emanating from the waste rock source is migrating in the deeper part of the aquifer. The high uranium content in the waters at greater depths may also be attributed to leaching of the buried bedrock surface by acid water of the waste dump. This U-rich water also has distinctly higher ²³⁴U/²³⁸U ratios. The samples at the water table closest to the waste rock source also showed quite significant concentration of uranium. Uranium in these waters occurs predominantly as stable and soluble uranyl carbonate complexes; part of the dissolved uranium is taken by the porous medium as it passes through, as shown by high concentrations of leachable uranium on the sediment of the aquifer.

Generally, the Greyhawk ground waters have a relatively low ²³⁴U/²³⁸U ratio which ranges between 0.95 and 1.85. Most samples have U ratios between 1.00 and 1.30. Migration of ²³⁴U-enriched water was observed at intermediate and bottom depths of the aquifer. The spatial distribution of isotope ratios in the aquifer indicates the migrating path of the contaminants emanating from the waste rock source. The enrichment of ²³⁴U over ²³⁸U is probably due to preferential leaching of ²³⁴U from the waste rock as well as from the bedrock.

The thermal neutron activation-delayed neutron counting technique is also applied to the analysis of uranium content in the water. The technique is non-destructive, rapid, moderately accurate and precise and appears satisfactory for uranium prospecting purposes.

The possibility of applying combined fission track and alpha track counting technique to determine isotopic ratios (²³⁴U/²³⁸U) is investigated in this programme. The ratios obtained by this technique are promising and generally are in good agreement with those determined on an alpha-particle spectrometry. This technique has a great potential in the determinations of ²³⁴U/²³⁸U ratio in natural water. However, some improvements on the technique are still needed to make the method more reliable, quantitative and rapid.

abstract: Master of Science (MS)


title: The Anticoagulant and Antithrombotic Properties of Human Prothrombin Fragment 1.2

contributor:
Blajchman, Morris A.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: A method for the preparation of human prothrombin fragment 1.2 (F1.2) from freshly clotted plasma was developed. Addition of exogenous F1.2 to citrated nonnal human plasma prolonged prothrombin time and activated partial thromboplastin time by 0.9 and 2.4 s/μM Fl.2, respectively. Delayed thrombin generation was not attributed to inhibition of tissue factor activity nor inhibition of factor X activation but to interference with phospholipid interactions in the prothrombinase complex. In mice, 500 μg (14 μM) of F1.2 gave 100% protection from tissue factor lethality, whereas 6 units (3 μM) of heparin was required for 100% protection. Either dose of F1.2 or heparin protected mice from thrombin-induced death. However, 500 μg of F1.2 was not effective in protecting mice from lethal effect of factor Xa and cephalin, while 0.75 units of heparin prevented such lethality. These findings demonstrate that human prothrombin F1.2 has anticoagulant and antithrombotic properties.

abstract: Doctor of Philosophy (PhD)


title: Large Scale Optimization of Analog Circuits with Microwave Applications

abstract:
This thesis addresses itself to computer oriented techniques for large scale optimization of analog circuits. New techniques for simulation and sensitivity analysis are described and are used to improve the performance of circuit optimization. A powerful automatic decomposition technique is developed directly enabling a normal optimizer to solve large circuit problems. Our theory is applied to the design of microwave circuits.

The status of large scale circuit optimization and the state-of-the-art of microwave CAD are reviewed. The necessity of circuit oriented optimization techniques is demonstrated by formulating design, modelling, diagnosis and tuning into optimization problems.

A comprehensive treatment of large change sensitivity computation for linearized circuits using generalized Householder formulus is presented. A technique for circuit response updating via a minimum order reduced system is developed. By avoiding re-analysis of the complete circuit, our method is responsible for efficient simulation of large circuits when a subset of the circuit parameters is frequently perturbed.

An elegant theory for simulation and exact sensitivity analysis of branched cascaded networks is described. Our approach explicitly takes the circuit-structure into consideration and does not deteriorate as the overall network becomes large. The practicality of the theory is illustrated by efficient optimization of microwave multiplexers consisting of multi-cavity filters distributed along a waveguide manifold. Examples of optimizing 12- and 16-channel multiplexers are provided.

A novel and general automatic decomposition technique for large scale optimization of microwave circuits is presented. The partitioning approach proposed by Kondoh for FET modelling problems is verified. The application of our technique is demonstrated by the large scale optimization of a 16-channel multiplexer involving 399 nonlinear functions and 240 variables.

abstract: Doctor of Philosophy (PhD)


title: The Acute Inflammatory Response during Enteric Infectious Disease

contributor:
Stadnyk, Andrew W.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
The acute inflammatory response is an organism's immediate reaction to injury. In mammals the response is facilitated by an abundance of molecules circulating in the plasma. These molecules are responsible for clotting the blood and chemotaxis of inflammatory cells. Polymorphonuclear leukocytes and monocytes usually comprise the cell infiltrate during acute inflammation.

Within several hours of a localised injury and the start of the acute inflammatory response, systemic indications of the response are detectable. A number of plasma glycoproteins, collectively referred to as the Acute Phase Proteins, change in concentration during acute inflammation. Acute Phase Proteins are synthesized primarily by the liver parenchymal cells, the hepatocytes. The molecules which induce hepatocytes to adopt Acute Phase Protein synthesis (hepatocyte-stimulating factors) arise from the inflammatory macrophages at the site of inflammation. The phenomena of the Acute Phase Protein changes constitutes the Acute Phase Protein Response. The predictable nature of the Acute Phase Protein Response, during inflammation caused by noxious agents, has led to the speculation that the response may serve as a manifestion of infectious diseases.

Certain intestinal-dwelling nematodes elicit an inflammatory response in the small bowel of their host. Nippostrongylus brasiliensis and Trichinella spiralis are two such parasites of rodents. It was important for an understanding of the nature of intestinal inflammation, to establish whether the Acute Phase Protein Response occurred in animals harboring the parasites.

Following a subcutaneous injection, N. brasiliensis larvae pass through the rat host's lungs before reaching and maturing in the intestine. Acute Phase Protein changes were detected in infected rats at the time at which the worms were passing through the lungs and following the establishment of the adults in the intestine. Infective T. spiralis must be ingested and subsequently mature in the small intestine. Adults live, and give birth to larvae, while living in an intracellular compartment comprised of intestinal epithelial cells. No Acute Phase Protein Response was detected during infection of rats by T. spiralis.

An infection by T. spiralis did not inhibit the Acute Phase Protein Response due to a second stimuli, and macrophage secretion of factors relevant to the Acute Phase Protein Response, from sites other than the intestine, was normal. An Acute Phase Protein Response was detected in animals which harbored concurrent N. brasiliensis and T. spiralis infections. No Acute Phase Protein Response was detected in rats into which mature N. brasiliensis larvae were transferred, in order to eliminate the lung stage of infection. It was concluded that the lung phase of an infection by N. brasiliensis was important in the genesis of the Acute Phase Protein Response during intestinal inflammation. Furthermore, it was concluded from these studies that inflammation in the rat intestine does not lead to the Acute Phase Protein Response.

When the intestinal cells of normal rats were examined for the production of factors which may induce the Acute Phase. Protein Response, it was shown that constitutive secretion of the relevant molecules occurred. Secretion of these factors increased during infection of rats by N. brasiliensis but declined during infection by T. spiralis. A rat intestinal epithelial cell line was used to demonstrate that these cells, in addition to macrophages, secrete molecules important in the regulation of the Acute Phase Protein Response. It was concluded that T. spiralis likely inhibited the constitutive hepatocyte-stimulating factor activity by infecting epithelial cells of the intestine.

The pathology that the rodent infections elicit are good models of inflammation for the study of mechanisms of the acute inflammatory response of the intestine.

abstract: Doctor of Philosophy (PhD)


title: Characterization and Identification of Hepatocyte Stimulating Factor (HSF) as Interferon Beta 2 (IFNβ₂) and its Role in the Acute Phase Response of Liver

contributor:
Gauldie, Jack
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
The acute phase response in mammals to tissue injury or infection is characterized by a number of systemic effects including fever, neutrophilia and increases in serum levels of liver-derived (synthesized by hepatocytes) acute phase proteins. Soluble mediators or cytokines released by cells of the monocyte/macrophage lineage have been implicated in the initiation of the increased synthesis of protein by hepatocytes and include Hepatocyte Stimulating Factor (HSF) and Interleukin-1 (IL-l). The nature of HSF and IL-1 and their activities in inducing acute phase protein synthesis in vitro by primary cultures of rat hepatocytes and by human Hep-G2 cells was examined. Human peripheral blood monoocyte (PBM) -derived HSF showed different characteristics than IL-1 upon separation by chromatography and gel electrophoresis. HSF strongly stimulated some acute phase proteins (rat α₂-macroglobulin and α₁-cysteine protease inhibitor, human fibrinogen and α₁-antichymotrypsin) whereas Il-1 strongly stimulated human α₁-acid glycoprotein.

Human PBM derived HSF showed biochemical similarities to another cytokine, Interferonβ₂ (IFNβ₂), that had previously been cloned from fibroblasts and from T-lymphocytes. HSF and 1FNβ₂ showed immunological similarities on the basis of antibody binding and activity inhibition assays. Cloned IFNβ₂ from T-cells showed potent inducing activity of acute phase protein synthesis and stimulated maximally the same proteins that did HSF. Both human fibroblast cultures and PBM cultures secreted HSF activity and possessed mRNA species that hybridized to a cDNA probe for IFNβ₂. These data suggest that human PBM derived HSF and human IFNβ₂. These data suggest that human PBM derived HSF and human IFNβ₂ are identical and that fibroblasts and T-lymphocytes as well as monocytes are capable of releasing Hepatocyte Stimulating Factor/lnterferonβ₂.

abstract: Doctor of Philosophy (PhD)


title: Retinylidene Iminium Salts and Related Systems

contributor:
Childs, R.F.
Chemistry

subject: Chemistry Chemistry

abstract:
This thesis encompasses some investigations into the structure and chemistry of iminium salts. The interest in this work stems from previous investigations of the visual pigment rhodopsin and a related protein, bacteriorhodopsin. Both of these proteins have been shown to consist of an iminium salt linkage between the chromophore and the protein. Also, these compounds are able to absorb light in the visible region of the spectrum and undergo efficient isomerization processes.

A series of iminium salts related to these natural chromophores were prepared and characterized by a variety of spectroscopic methods in both solution and the solid states. In particular, the ground state structure of these positively charged molecules was examined in terms of charge delocalization, cation anion interactions and chromophore conformation. These properties have been previously suggested to be important in the natural chromophores. One conclusion of this study was that positive charge in these "model" systems is localized in the iminium portion of the molecule. Secondly, it was found that the conformations of these molecules may be different in the solid state from that in solution. In at least one case, the conformation of the chromophore was found to be identical to that found in the natural pigment, bacterior-hodopsin.

The photochemical and thermal reactivity of several of the prepared iminium salts was also investigated using high field ¹H NMR spectroscopy as an analytical method to directly monitor these reactions. Using this technique, it was found that several of the iminium salts studied underwent efficient trans to cis photoisomerization reactions. In one case, the efficiency of this reaction was very close to that found for bacteriorhodopsin. Moreover, the primary photoproducts formed in these reactions were found to be stable under the experimental conditions used. This was in contrast to previously reported investigations of similar compounds, where cis/trans thermal isomerizations occurred in the reaction medium.

abstract: Doctor of Philosophy (PhD)


title: O-IF₄O- Derivatives of Xenon and Main-Group Elements

contributor:
Schrobilgen, G.J.
Chemistry

subject: Chemistry Chemistry

abstract:
With improved syntheses of the O-IF₄O- group precursors, HOIOF₄ and IO₂F₃, an extensive derivative chemistry of the O=IF₄O- group has begun to emerge. The xenon(lI) derivatives, FXeOIOF₄ and Xe(OIOF₄)₂, have been shown by their solution ¹⁹F and ¹²⁹Xe NMR spectra to result from the reaction between IO₂F₃ and XeF₂ in SO₂C1F, CFCl₃ and BrF₅ solvents. The covalently bonded O=IF₄O- groups are shown to be equilibrium mixtures of their cis- and trans-isomers and are oxygen bonded to xenon. The solid derivative, cis, cis-Xe(OIOF₄)₂ has been isolated from the acid displacement reaction between Xe(OTeF₅)₂ and the stronger protonic acid mixture cis/trans-HOIOF₄ under neat conditions, or in CFCl₃ solvent. A mixture of the cis and trans-derivatives of FXeOIOF₄ were prepared by the stoichiometric reaction of IO₂F₃ with XeF₂ in anhydrous HF followed by removal of the solvent under vacuum. Both cis/trans-FXeOIOF₄ and cis. cis Xe(OIOF₄)₂ were characterized by ¹⁹F and ¹²⁹Xe NMR spectroscopy and low-temperature Raman spectroscopy. A comparison among ¹²⁹Xe NMR chemical shifts for resulted in an effective group electronegativity order -OSO₂F > trans- O=IF₄O- > -OTeF₅.

The thermal decomposition reactions of FXeOIOF₄ and cis. cis-Xe(OIOF₄)₂ have been studied by ¹⁹F NMR spectroscopy and Raman spectroscopy. In the latter case, the novel O=lF₄O- derivative, F₄OIOOIOF₄, has been prepared by the controlled thermal decomposition of cis. cis-Xe(OIOF₄)₂ as well as from the reaction of IO₂F₃ and KrF₂ and characterized by ¹⁹F NMR spectroscopy as the Raman spectroscopy.

Higher oxidation state derivatives of xenon were, until the present work, known only for -OTeF₅. The O=IF₄O- derivatives, F₃XeOIOF₄ and OXeF₃OIOF₄, have been identified by ¹²⁹Xe and ¹⁹F NMR spectroscopy as the products of the insertion reactions between IO₂F₃ and XeF₄ and XeOF₄ respectively. In addition, the mixed Xe(VI) derivatives, OXe(OIOF₄)x(OTeF₅)₄_x, resulting from the reaction of HOIOF₄ with OXe(OTeF₅)₄, have been identified in situ by ¹²⁹Xe NMR spectroscopy. The solid product isolated from the neat reaction of HOIOF₄ with OXe(OTeF₅)₄ has been shown by ¹²⁹Xe NMR spectroscopy in solution and Raman spectroscopy in the solid state, to consist of a mixture of cis- and trans-isomers of the novel Xe(VIII) derivative, O₃Xe(OIOF₄)x(OTeF₅)₂_x.

Preliminary evidence obtained from Raman spectroscopy as well as ¹¹B and ¹²⁵Te NMR spectroscopy, suggests that novel O-IF₄O- derivatives of boron, mercury and tellurium have also been formed.

abstract: Doctor of Philosophy (PhD)


title: Technetium(VII) and Rhenium(VII) Oxofluorides and the Role of Noble-Gas Fluorides in Their Syntheses

subject: Chemistry Chemistry

abstract: Technetium, a β-particle emitter with a half-life of 2.12 x 10⁵ years, represents 6% of the fission products in commercial nuclear reactors. Although ⁹⁹Tc is not released during normal operation of nuclear power reactors, technetium may be introduced into the environment at other stages of the nuclear fuel cycle and is particularly prevalent as a contaminant near uranium enrichment facilities using recycled UF₆. Until recently, the only known fluorine derivatives of Tc were the two binary fluorides, TcF₅ and TcF₆, two oxofluorides, TcOF₄ and TcO₃F and the four anions TcF₆²⁻, TcF₆⁻, TcF₇⁻ and TcF₈²⁻. The fluorine chemistry of technetium was recently extended with the preparation of the fluorine-bridged infinite-chain polymer TcO₂F₃ by fluorination of TcO₃F by XeF₆ in anhydrous HF. The purpose of this work has to study the fluoride-ion donor and acceptor properties of TcO₂F₃ and its rhenium analog, ReO₂F₃, as well as the synthesis and characterization of TcOF₅ and possibly TcF₇. The significant Lewis acidity of TcO₂F₃ toward the fluoride ion and the CH₃CN led to the prepation of the TcO₂F₄⁻ anion as its Li⁺, Cs⁺ and N(CH₃)₄⁺ salts, and the TcO₂F₃(CH₃CN) adduct. Characterization by ¹⁷O, ¹⁹F, ⁹⁹Tc NMR and Raman spectroscopy established that the TcO₂F₄⁻ anion has a cis-dioxo geometry, which was confirmed by a single-crystal X-ray structure determination of Li⁺TcO₂F₄⁻. By analogy, ReO₂F₃ is also a Lewis acid forming M⁺ReO₂F₄⁻ [M = Li, Na, K, Cs, N(CH₃)₄] and ReO₂F₃(CH₃CN). In addition, the oligomeric anions Re₂O₄F₇⁻ and Re₃O₆F₁₀⁻ were isolated and their structures were determined by X-ray diffraction. These anions consist of two and three fluorine-bridged ReO₂F₃-units in which the oxygen atoms are cis to each other and trans to the bridging fluorines. The X-ray structure of ReO₂F₃ was also determined for the first time and is similar to that of TcO₂F₃. Both TcO₂F₃ and ReO₂F₃ behave as fluoride-ion donors, dissolving readily in hydrogen fluoride solutions acidified with the strong Lewis acids AsF₅ and SbF₅, and forming MO₂F₃∙PnF₅ adducts (M = Tc, Re; Pn = As, Sb). The structures of TcO₂F₃∙SbF₅ and ReO₂F₃∙SbF₅ consist of infinite chains of alternating fluorine-bridged MO₂F₄⁻ and SbF₆-units with the oxygen atoms cis to each other and trans to the bridging fluorines. The crystal structure of TcO₂F₃∙XeO₂F₂, a byproduct of the synthesis of TcO₂F₃, was also determined by X-ray crystallography and consists of TcO₂F₃ infinite chains linked together by a layer of XeO₂F₂ through xenon-fluorine long contacts. The structures of TcO₂F₃ and ReO₂F₃ in SO₂CIF solution were elucidated by ¹⁹F NMR spectroscopy and consist of cyclic fluorine-bridged species, (MO₂F₃)n, where n= 3 for M= Tc and n=3, 4 and 5 for M=Re. A new technetium(VII) oxofluoride, TcOF₅, was prepared from the reaction of TcO₂F₃ with an excess of KrF₂ in anhydrous HF. This volatile orange solid was characterized by NMR and Raman spectroscopy which confirmed its pseudoctahedral geometry. The fluoride-ion donor behaviour of TcOF₅ was investigated resulting in the preparation of the dinuclear cation Tc₂O₂F₉⁺ as its Sb₂F₁₁⁻ and AsF₆⁻ salts, and the structure of Tc₂O₂F₉⁺Sb₂F₁₁⁻ was determined by X-ray crystallography. Attempts to prepare the heptacoordinated species TcOF₆⁻ and TcF₇ were unsuccessful.

abstract: Doctor of Philosophy (PhD)


title: Modelling of Regional Sanitary Sewerage Networks for Minimum Cost

contributor:
Smith, Alan A.
Civil Engineering

subject:
Civil Engineering
Civil Engineering

abstract:
A computer model is developed for the solution of regional sanitary sewerage systems on a minimum cost basis. The regional system is considered to consist of a substantial number of alternative transportation (collection) routes, several potential treatment facilities and a receiving body of water which is able to accept the effluents from these facilities. The model, using a steady state analysis, facilitates the selection of a good collection network from the large number of possible networks, the selection of good depth-diameter combinations for each link in this final network and the selection of the size and number of treatment facilities which should be involved in the regional system. In addition, the required treatment efficiency of each facility will be determined so that a specified water quality goal may be satisfied.

A major point to be considered in attempting to select a least cost system is the tradeoff in costs between constructing a few, large, centralized treatment facilities (thereby benefitting from the economies of scale which generally exist) and the extra cost associated with transporting the wastes an extra distance to these centralized plants. The possibility of higher treatment efficiencies being required at these centralized treatment facilities (due to a greater stress being exerted on the water quality of the receiving body of water) should also be considered. The piping costs are a function of the wasteflow. Fixed costs may be included in the cost function. The treatment plant costs are a function of both wasteflow and treatment efficiency. Fixed costs may also be included when determining the treatment plant costs.

Linear programming and dynamic programming techniques are used as a basis for the computer model. Additional subroutines were requires to ensure that the technical constraints (for example, the minimum and maximum velocity constraints) were satisfied and to provide the missing components which are necessary to develop a complete computer package.

abstract: Master of Engineering (ME)


title: Statistical Classification of Brainstem Auditory Evoked Potentials and The Effects of Local Cooling on Canine Spinal Cord Blood Flow

contributor:
Ghista, Dhanjoo N.
Neuroscience

subject:
Neuroscience and Neurobiology
Neuroscience and Neurobiology

abstract:
Brainstem auditory evoked potentials (BAEPs), the time locked scalp recorded electrical responses to auditory stimuli are clinically useful for diagnosing and monitoring the disorders of neurological system. The first part of the thesis presents the development and evaluation of computer based statistical classifiers to recognize normal and patients' BAEPs. The classifiers using time domain features; namely latencies of peaks V, IV and III of BAEPs, gave the optimal performance as measured by accuracy (85.3%), sensitivity (80%) among other indices. Power spectra of BAEPs in normals show three main frequency bands. In a second formulation of classifiers, three features, each feature representing the total power in each of the three frequency bands were used. The classifiers designed with these frequency domain features yielded a performance with accuracies upto 77%. Both of these classifiers may be used to assist the clinician while assessing the BAEPs.

The second part of the thesis examines the effects of cooling on canine spinal cord blood flow (SCBF). The SCBF is an important physiological variable altered during spinal cord injury (SCI). Localized cooling of the spinal cord improves functional recovery after SCI. Hence, the effects of cooling on SCBF in normal canine cord were studied. A computerized system to measure the SCBF using hydrogen polarography at two control sites and two cooled sites was developed. In five dogs, SCBF decreased to 50% of the normothermic values during cooling of the cord to a temperature of 16 degrees Celsius. The SCBF did not change at control sites. It is postulated that following SCI decreased SCBF due to localized cooling tends to prevent the outpouring of edema fluid and other toxic factors from the injured vessels, preserving the cord function. Thus, the finding of decreased SCBF during spinal cord cooling is clinically relevant.

abstract: Doctor of Philosophy (PhD)


title: Maternal Attachment to the Unborn Child A Developmetal Study

contributor:
Campbell, Dugal
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
Conclusions about the effects of pregnancy in women - how they feel about being pregnant and their attitudes to the unborn child - have been based almost exclusively upon observations of primigravidas. It is claimed that a satisfying and/or more stressful than later pregnancies. The research for this thesis suggests that some of these claims are mistaken.

This thesis examines the similarities and the differences between a group of primigravidas and a group of second pregnancy multigravidas on a range of maternal attitudes during pregnancy. The predictions were based on findings from a pilot study conducted at McMaster University Medical Centre. An interview was designed to elicit the women's thoughts and feelings about their expected infant and about themselves as mothers.

Primigravidas and multigravidas were found to be equally positive about the coming baby and equally anxious about their capacities as mothers. The primigravidas reported significantly more anxiety about the welfare of the expected infant and the multigravidas reported significantly more conflict and negative feeling. The common and unique features of a first and a second pregnancy are discussed. The findings suggest that new adaptations and family real realignments accompany the birth of each child.

A third sample of women was examined using the same measures. Comparisons were made between a group of multigravidas who had lost an infant by stillbirth or neonatal death and a group of multigravidas without a history of infant loss. Women who had previously lost an infant were found to be still mourning the death of the first infant and less invested in a relationship with the expected infant. The thesis discusses the effects of infant loss upon women and makes recommendations for the clinical management of bereaved mothers.

abstract: Doctor of Philosophy (PhD)


title: Factors Contributing to Breathlessness

contributor:
Jones, N.L.
Killian, K.J.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
Breathlessness may be defined as the conscious awareness of respiratory muscle effort. As with any skeletal muscle it is to be expected that the sense of effort increases as the pressure generated by this muscle increases as well as the velocity and extent of shortening. The purpose of this study was; 1. to quantify the intensity of breathlessness during exercise and respiratory loading; 2. to isolate the contributions of inspiratory muscle pressure to breathlessness; 3. to see if extent of shortening, velocity of shortening, frequency (fb), and duty cycle (Ti/Ttot) contribute to the intensity of breathlessness independently. The intensity of inspiratory muscle pressure was quantified by measurement of mouth pressure (Pm) as well as the estimated esophageal pressure (Pes), the extent of shortening by tidal volume (Vt), and the velocity of shortening by inspiratory flow (Vi). Six normal subjects underwent eight incremental (100 kpm/min/min) exercise tests on a cycle ergometer to maximum capacity. The first and last test were unloaded and the intervening tests were performed with external added resistances and elastances presented in random order. The resistances and elastances were selected to provide a wide range inspiratory pressures, tidal volumes, and flows. The inspiratory resistive loads (33, 57, 73 cm H2 O/1/s) were used mainly to vary the flow (functional velocity of shortening of inspiratory muscles). The inspiratory elastic loads (21, 41, 52 cm H2O/1) were used mainly to vary the tidal volume (functional extent of shortening). At rest and at the end of each min during exercise the subjects estimated the intensity of breathlessness (Y) by selecting a number ranging from 0-10 (Borg psychophysical scale), 0 indicating no appreciable breathlessness and 10 the maximum tolerable sensation.

When the velocity was altered (resistive loading study) breathlessness was significantly related to inspiratory pressure (p<0.0001), peak inspiratory flow (p<0.0001), frequency of breathing (p<0.01) and duty cycle (p<0.01). When the extent of shortening was altered (elastic loading study) breathlessness was significantly related to inspiratory pressure (p<0.001), tidal volume (p<0.001), and frequency of breathing (p<0.001).

The results indicated that the perceived magnitude of breathlessness is closely related to the pressure generated by the inspiratory muscles and the shortening pattern of these muscles as reflected in Vt, Vi, Fb, and Ti/Ttot. The results also indicated that the contribution of these factors to the intensity of breathlessness differs quantitatively between loaded and unloaded breathing. Thus, in normal unloaded breathing the velocity and degree of shortening are important factors contributing to breathlessness during exercise; with resistive loading the inspiratory pressure, the velocity, and the duty cycle are important; with elastic loading the inspiratory pressure, the extent of shortening, and the frequency are important.

The major contributions of these studies were in quantifying the intensity of breathlessness, and defining both the factors contributing to breathlessness and the relative importance of each.

abstract: Doctor of Philosophy (PhD)


title: Chip Formation and Surface Integrity in High Speed Machining of Hardened Steel

contributor:
Elbestawi, M. A.
Mechanical Engineering

subject:
Mechanical Engineering
Mechanical Engineering

abstract: Increasing demands for high production rates as well as cost reduction have emphasized the potential for the industrial application of hard turning technology during the past few years. Machining instead of grinding hardened steel components reduces the machining sequence, the machining time, and the specific cutting energy. Hard turning is characterized by the generation of high temperatures the formation of saw toothed chips, and the high ratio of thrust to tangential cutting force components. Although a large volume of literature exists on hard turning, the change in machined surface physical properties represents a major challenge. Thus, a better understanding of the cutting mechanism in hard turning is still required. In particular, the chip formation process and the surface integrity of the machined surface are important issues which require further research. In this thesis, a mechanistic model for saw toothed chip formation is presented. This model is based on the concept of crack initiation of the free surface of the workpiece. The model presented explains the mechanism of chip formation. In addition, experimental investigation is conducted in order to study the chip morphology. The effect of process parameters, including edge preparation and tool wear on the chip morphology. The effect of process parameters including edge preparation and tool wear on the chip morphology, is studied using Scanning Electron Microscopy (SEM). The dynamics of chip formation are also investigated. The surface integrity of the machined parts is also investigated. This investigation focusses on residual stresses as well as surface and sub-surface deformation. A three dimensional thermo-elasto-plastic finite element model is developed to predict the machining residual stresses. The effect of flank wear is introduced during the analysis. Although residual stresses have complicated origins and are introduced by many factors, in this model only the thermal and mechanical factors are considered. The finite element analysis demonstrates the significant effect of the heat generated during cutting on the residual stresses. The machined specimens are also examined using x-ray diffraction technique to clarify the effect of different speeds, feeds, and depths of cut as well as different edge preparations on the residual stress distribution beneath the machined surface. A reasonable agreement between the predicted and measured residual stress is obtained. The results obtained demonstrate the possibility of eliminating the existence of high tensile residual stresses in the workpiece surface by selecting the proper cutting conditions. The machined surfaces are examined using SEM to study the effect of indifferent process parameters and edge preparations on the quality of the machined surface. The phenomenon of material side flow is investigated to clarify the mechanism of this phenomenon. The effect of process parameters and edge preparations on sub-surface deformation is also investigated.

abstract: Doctor of Philosophy (PhD)


title: Safety Characteristics of a Suspended-Pellet Fission Reactor System

contributor:
Wilkinson, D.S.
Harms, A.A.
Engineering Physics

subject:
Engineering Physics
Engineering Physics

abstract: A new fission reactor system with passive safety characteristics to eliminate the occurrence of loss-of-coolant accidents, reduce reactivity excursion effects, and which also provides for closure of the nuclear fuel cycle through on-site spent fuel management is examined. The concept uses multi-coated fuel pellets which are suspended by an upward moving coolant in vertical columns of the reactor core and electro-refining elemental separation to remove selected fission products prior to actinide recycling. The possibility of fuel melt following a loss-of-coolant is avoided as a decrease in coolant flow results in the removal of fuel from the core through the action of gravity alone. Average fluid velocities in the columns which are necessary to suspend the pellets are calculated and found to be consistent with the necessary heat extraction to yield ~1-10MWth per column. The total output power of such suspended pellet-type reactors is compared to the power necessary to provide the suspending fluid flow, yielding favourable ratios of ~10² - 10³ The reduction of reactivity excursion tendencies is envisaged through an ablative layer of material in the pellets which sublimates at temperatures above normal operating conditions. In the event of a power or temperature increase the particles fragment and thereby change their hydrodynamic drag characteristics, thus leading to fuel removal from the core by elutriation. Comparison of nuclear-to-thermal response times and elutriation rates for limiting power transients indicate that the present design assets in reactivity excursion mitigation. Closure of the nuclear fuel cycle is attained through a spent fuel management strategy which requires only on-site storage of a fraction of the fission products produced during reactor operation. Electro-refining separation of selected fission products combined with complete actinide recycling yields no isolation of plutonium or highly enriched uranium during the procedure. The out-of-core waste stream has a significantly reduced radioactivity, volume and lifetime compared to the once-through waste management strategy and thus provides an alternative to long-term geological disposal of fission reactor wastes. The Pellet Suspension Reactor concept possesses some unique operating characteristics and, additionally, is shown to be similar to conventional fission reactors in terms of common performance features.

abstract: Doctor of Philosophy (PhD)


title: Experimental Studies of Static Mixers and Twin Screw Extruders

contributor:
Wood, Philip E.
Chemical Engineering

abstract: The laminar flow field in a Kenics KM® static mixer and a Werner and Pfleiderer ZSK-30® twin screw extruder (TSE) has been studied using laser induced fluorescence (LIF) coupled with digital image analysis, particle image velocimetry (PIV) and laser Doppler anemometry (LDA). The objective of this study was to observe the flow fields in these two devices, to determine their mixing capabilities qualitatively and quantitatively. Mixing in the static mixer was quantified by measurement of the number average striation thickness, variance of striation widths and interfacial area for elements with 90 degrees of twist. From flow visualisation and LDA measurements, transitions were observed in the flow where vortices developed above the first and second elements. These vortices did not appreciably enhance mixing after 4 to 5 elements with an aspect ratio (L/D) of 1.0. The velocity field measured over the first four elements (L/D = 1.5), captured the mixing nature of the static mixer, where flow was split at the leading edge and recombined at the trailing edge of the elements. Recirculations in the radial plane were observed where fluid flowed from the high-pressure side of the element forward out along the tube wall to the low-pressure side or suction side. The radial flow field required a development length to allow the flow to build in magnitude. The rate of deformation analysis on the flow field indicated that mixing efficiency would be increased if the first element had a larger helix angle. The highest rates of deformation were measured at the junctions between elements, and between the element and tube surfaces. The visualisations coupled with image analysis for the TSE demonstrated clearly that the mixing was enhanced by placing a reverse conveying element directly after the last set of kneading discs in the mixing section. The velocity results for the screw profile with extended first and last discs (geometry A) showed an increase in back flow and recirculations with increasing screw rotation. When a forward conveying element was used before and after the kneading discs (geometry B), higher radial and lower axial velocities were measured. The fluid in the direction of rotation and no back-mixing or recirculations in the flow were measured. Results of a 3D model for the simulation of flow in the kneading disc region and the PIV measurements were compared. Results for geometry A are in good qualitative agreement for low flow rates. Geometry B showed better agreement at higher flow rates compared to lower flow rates. The performance of the kneading discs were characterized based on the shear, elongation and the magnitude of the rate of deformation tensor within the measured flow fields. For the various cases of screw rotation speed, the largest rates of deformations (elongation and shear) were seen at the first and last disc of the kneading block where transitions occurred.

abstract: Doctor of Philosophy (PhD)


title: Product and Process Improvement Using Latent Variable Methods

contributor:
MacGregor, John F.
Chemical Engineering

abstract: This thesis considers the utilization of historical process data for three different process engineering problems. Latent variable methods such as Principal Components Analysis (PCA) and Partial Least Squares (PLS) are shown to be key tools for dealing with the highly correlated variables typically found in process operating data and for ensuring feasibility of the solutions. The restrictions and limitations encountered by any databased approach are recognized and discussed. The problem of designing process conditions that yield a new product grade quality within the range of already existing grades is addressed by latent variable regression models and their inversion. Latent variable techniques allow for models that not only describe the relationship between process conditions. This leads to the design of new conditions that are consistent with the plant operations from the past. Feasibility issues of both the new quality specifications as well as the predicted operating conditions are addressed. The approach is illustrated on a simulated process and three industrial processes. The related topic of moving the production of a particular product grade from a plant A to another plant B when both plants have already produced a similar range of grades is treated as well. Since the two plants may differ in size, configuration etc. the process conditions for one grade may be very different in the two plants. A latent variable method is proposed which uses data from both plants to predict process conditions for plant B for a grade previously produced only in plant A. The issue of feasibility is again addressed for both product quality and process conditions. The last part of the thesis explores the problematic issue of utilizing large process operating databases for process performance improvement. The major problem found with using normal operating data for this purpose is correlation among manipulated variables and disturbances as caused by feedback operation or other operating strategies. Such correlation is shown to impede the extraction of causal information from the database, which is necessary in order to infer better process conditions. This implies that only in exceptional circumstances would it be feasible to use empirical databased methods for process optimization.

abstract: Doctor of Philosophy (PhD)