title: Model-based clustering algorithms, performance and application

contributor:
Wong, K. M.
Luo, Z.Q.
Electrical and Computer Engineering

abstract: The main contributions of this thesis are the development of new clustering algorithms (with cluster validation) both off-line and on-line, the performance analysis of the new algorithms and their applications to intrapulse analysis. Bayesian inference and minimum encoding inference including Wallace's minimum message length (MML) and Rissanen's minimum description length (MDL), are reviewed for model selection. It is found that the MML coding length is more accurate than the other two in the view of quantization. By introducing a penalty weight, all criteria considered here are cast into the framework of a penalized likelihood method. Based on minimum encoding inference, an appropriate measure of coding length is proposed for cluster validation, and the coding lengths under four different Gaussian mixture models are fully derived. This provides us with a criterion for the development of a new clustering algorithm. Judging from the performance comparison with other algorithms, the new clustering algorithm is more suitable to process high dimensional data with satisfactory performance on small and medium samples. This clustering algorithm is off-line because it requires all the data available at the same time. The theoretical error performance of our clustering algorithm is evaluated under reasonable assumptions. It is shown here how the dimension of data space, the sample size, the mixing portion and the inter-cluster distance affect the performance of our clustering algorithm to detect the true number of clusters. Furthermore, we examine the impact of the penalty weight under the framework of the penalized likelihood method. It is found that there is a range of the penalty weight within which the best performance of our clustering algorithm can be achieved. Therefore, with some supervision we could adjust the penalty weight to further improve the performance of our clustering algorithm. The application of our clustering algorithm to intrapulse analysis is investigated in detail. We first develop the pre-processing techniques including data compression for received pulses and formulated the problem of emitter number detection and pulse-emitter association into a multivariate clustering problem. After applying the above (off-line) clustering algorithm here, we further develop two on-line clustering algorithms, one is based on some known thresholds while the other is based on a model-based detection scheme. Performance on intrapulse data by using our pre-processing techniques and clustering algorithms is reported, and the results demonstrate that our new clustering algorithms are very effective for intrapulse analysis, especially the model-based on-line algorithm. Finally, the DSP implementation for intrapulse analysis is considered. Some relevant physical parameters are estimated such as the likely maximal incoming pulse rate. Then a suitable system diagram is proposed and its system requirements are investigated. Our on-line clustering algorithm is implemented as a core classification module on a TMS320C44 DSP board.

abstract: Doctor of Philosophy (PhD)


title: Integrated distributed feedback lasers and electroabsorption modulators fabricated using helium-plasma-assisted indium phosphide defect induced quantum well intermixing

contributor:
Simmons, John G.
Thompson, David A.
Engineering Physics

subject:
Engineering Physics
Engineering Physics

abstract: An integrated DFB laser and electroabsorption modulator was fabricated by using a novel quantum-well-intermixing technique that uses the defects from a layer of InP grown by He-plasma-assisted gas source molecular beam epitaxy (He*-InP). This is the first investigation into the He*-InP defect induced intermixing, and the first time a device has been fabricated by using this technique. The first part of this thesis outlines the first investigation into the effects of defects within a layer of He*-InP on annealing-induced quantum-well intermixing. Such a layer can be used to either decrease or increase the total amount of intermixing depending upon the placement of the He*-InP layer relative to the QW and the thickness of the layer. When the layer is far from the QW (∼0.5μm ), the total amount of intermixing is decreased. When the layer is close to the QW, the total amount of intermixing can be increased as well as being accompanied by a reduction of the photoluminescence intensity. The main benefit of this intermixing technique is that, unlike dielectric-enhanced intermixing, it is possible to regrow over material that has been intermixed by the He*-InP defect. The He*-InP defect-induced-intermixing technique has been applied to the fabrication of an integrated electroabsorption modulator and a distributed feedback laser. The techniques developed to fabricated the integrated device are discussed in detail in the second part of the thesis, followed by the device results. The device characteristics vary with device geometry. For example, the extinction ratios range from 9-16dB for voltage of 3V applied to a 400μm modulator due to the variation of the lasing wavelength with ridge width (for a 3QW structure). The threshold currents of discrete, 600μm long DFB lasers ranged from 18 to 35mA depending on its ridge width and where on wafer it was taken from.

abstract: Doctor of Philosophy (PhD)


title: Bargaining Structure and Bargaining Outcomes

contributor:
Kuhn, P.J.
Harrison, A.
Osborne, M.J.
Economics / Economic Policy

subject: Economics Economics

abstract:
A recent development in the analysis of strikes and contract negotiations strategic bargaining models with asymmetric information -- allows us to study bargaining structure and outcomes via its effects on information transfer and learning among parties to bargaining. This thesis continues this new approach and attempts to add to our knowledge of bargaining structure, both theoretically and empirically.

The whole thesis can be viewed as three main essays. In the first main essay(Chapter 2), we study learning and information transfer among unions when negotiations are sequential and there is no collusion among either unions or firms. That chapter attempts to further our understanding of relative rewards, imitation and learning. The model, which considers two union-firm bargaining pairs, generates an interest by workers in each other's wages which is based on learning their own firm's ability to pay by observing the preceding negotiations. But rather than being socially harmful, as it can be in the "informational cascade" literature, learning from actions of the others is, in a number of cases, socially beneficial. This is because learning reduces the costly mistakes made in bargaining due to asymmetric information. Using a large sample of Canadian contract negotiations for the period from 1965-1988, we find strong evidence that the more negotiations which have been concluded in the recent past in a union's industry, the less likely is a strike to occur. This can be seen as relatively convincing evidence that some social learning, with beneficial social consequences, does occur among unions negotiating wages within an industry.

In the second main essay (Chapter 3), we use a model of learning among unions to compare bargaining outcomes in various bargaining structures and examine the effects of centralization when negotiations are simultaneous. Existing formal models of bargaining structure and outcomes typically ignore one or both of two key issues: the issue of asymmetric information and the nature of bargaining process simultaneous versus sequential negotiation). Among other things, this means that they cannot capture the implicit coordination, or' social learning, in decentralized bargaining structures. Neither can they examine the wage leapfrogging phenomenon that has been suggested as a potential important disadvantage of decentralized bargaining structures. The current model allows us to examine these key issues. We found that when negotiations are simultaneous, collusion by firms or by both firms and unions reduces expected wage settlements and raises strike incidence since they reduce learning and information transfer among unions in contract negotiations.

In the model of learning among unions examined in the second main essay, there are clear first mover disadvantages for both unions and firms. Early negotiations generate valuable information about firms' ability to pay which unions in later negotiations can use to improve their wage settlements. Unions have an incentive to free ride and delay their wage settlements and let other unions conclude their negotiations first. In the third main essay (Chapter 4), we examine this information externality and interpret the delaying of wage settlements without strikes as holdouts. As in Cramton and Tracy's model of holdouts (1992), the model predicts that holdouts should be shorter and less frequent when the wage settlement in the existing contract is lower, and when the unions are more optimistic about the firm's ability to pay. But the model also has a number of predictions about some issues on which Cramton and Tracy's model is silent, one of which is the following: as the number of unions in the model expands, the above information externality is exacerbated, generating longer holdouts in equilibrium. This implication is tested using the large sample of Canadian contract negotiations used in the first essay, yielding strong evidence that the larger the number of negotiations taking place at the same time, the greater are both holdout incidence and duration.

abstract: Doctor of Philosophy (PhD)


title: Stratigraphy and sedimentology of the Lower Triassic Montney Formation, Peace River Arch area

contributor:
Walker, Roger G.
Geology

subject: Geology Geology

abstract: The Lower Triassic Montney Formation in the Peace River Arch area forms a sedimentary wedge up to 350 m thick, deposited on the craton margin. This study, based on 127 cores and about 1300 well logs, shows that the Montney Formation is characterized by overall southwesterly-dipping clinoform deposits with a maximum dip of about 0.3°. Based on prominent well log markers, the Montney Formation has been divided into seven depositional units lettered A through G. Deposition of the Montney Formation was strongly influenced by tectonic activity, and two major basin reorganizations occurred: one between Unit A and Unit B and the other between Unit F and Unit G. The overall sediment source for the Montney Formation was to the northeast, but at least for Unit B and Unit C, the main source was to the southeast. In the deeper part of the basin (southwest), the Montney Formation commonly contains turbidite deposits. Two styles of turbidite depositional systems developed: an unchannelized sheet-like system and a channel-related system. Unchannelized sheet-like turbidite systems occur in several stratigraphic units and constitutes the bulk of turbidite sedimentation, whereas the channel-related turbidite system developed only in Unit C. Here, an incised channel cuts down as much as 40 m into underlying sediment. It is relatively straight, trending southeast to northwest for a distance of 70 km. At the distal end of the channel, it turns sharply to the southwest, following a downthrown fault block. Upslope, the width of the channel is about 1 km, but farther downslope (northwestward) it widens to 3-5 km. The turbidites are mostly thick and structureless fine-grained sandstones. Upslope the sandstones are completely confined within the incised channel, but farther downslope they spread out of the incised channel for a distance of about 10 km. Synsedimentary faulting controlled the thickness of accumulated sediment and sediment facies. Thick accumulations of sand occur in downthrown fault blocks whereas thinner and/or muddier sediments were deposited in uplifted blocks. The turbidite systems of the Montney Formation were developed in relatively shallow environments, not deeper than a few hundred meters. The development of the Montney turbidite systems may not have been related to global sea level fluctuations, but local tectonic activity.

abstract: Doctor of Philosophy (PhD)


title: The Aggregated Spatial Logit Model: Theory, Estimation And Application

contributor:
Kanaroglou, P.S.
Geography

subject:
Geography
spacial logit model

abstract: In problems of spatial choice, the choice set is often more aggregated than the one considered by decision-makers, typically because choice data are available only at the aggregate level. These aggregate choice units will exhibit heterogeneity in utility and in size. To be consistent with utility maximization, a choice model must estimate choice probabilities on the basis of the maximum utility within heterogeneous aggregates. The ordinary multinomial logit model (OMNL) applied to aggregate choice units fails this criterion as it is estimated on the basis of average utility. In this thesis, the aggregated spatial logit model, which utilizes the theory underlying the nested logit model to estimate the appropriate maximum utilities of aggregates, is derived and discussed. Initially, the theoretical basis for the model is made clear and an asymptotic version of the model is derived. Secondly, the model is tested in a simulated environment to demonstrate that the OMNL model lacks the generality of the aggregated model in the presence of heterogeneous aggregates. Thirdly, full endogenous estimation of the aggregated model is studied with a view toward finding the best optimization algorithm. Finally, with all the elements in place, the model is tested in an application of migration from the Canadian Atlantic Provinces.

abstract: Doctor of Philosophy (PhD)


title: The Young Heidegger

contributor:
Madison, G. B.
Philosophy

subject: Philosophy Philosophy

abstract: Using his recently published lecture courses from 1919 to 1926, I tell the story of Heidegger's youthful thought, w hich has survived over the years as a "rumor," if not a legend. More specifically, I attempt a deconstructive reading of his later thought by tracing the major themes of his question of being back to their origin in his youthful period. I present these themes as the end of philosophy, the other beginning for the being-question, and the constant initiation of this new beginning as an ongoing way. I argue that the real turn in his thinking is not found in a turn from his 1927 "Being and Time" to his later works after 1930, but rather in his turn away from the metaphysics of his very early 1913 doctoral dissertation and the 1916 habilitation writing to his thought in the early twenties. Regarding the theme of the end of philosophy, I should that the young Heidegger already criticized the three epochs of metaphysics (the ancient, the medieval, and the modern), and that he did this with the help of Aristotle's critique of Plato's idea of the good; Luther's attack on Aristotlian scholasticism and Kierkegaard's critique of Hegelianism; and the critique of Neo-Kantianism in Husserl's "Sixth Investigation" and in Dilthey's philosophy of life. Regarding the theme of the other beginning for the being-question, I show that he posed this question as the question of "being in and through life," which he investigated in terms of the three intentional moments of world, factical life, and temporalizing. Regarding the theme of the way-character of his being-question, I show that he understood his philosophy as the "formal indication" of a way for interpretively showing the things themselves. In my Conclusion, I argue for the critical appropriation of his later thought in the light of the existential-phenomenological problematic and language of his youthful period, which provides us with a philosophical Rosetta stone for demythologizing and translating his later mytho-poetic, speculative language into a more familiar and natural lexicon.

abstract: Doctor of Philosophy (PhD)


title: How Text Difficulty and Reader Skill Affect Reliance on Word and Content Overlap in Reading Transfer

contributor:
Levy, B.A.
Psychology

subject: Psychology Psychology

abstract: Rereading has been advocated as a useful technique for rehabilitating poor readers (e.g. Samuels, 1979). The purpose of this thesis was to examine what was remembered after reading a text to discover how this memory can be used to increase the fluency of reading related texts. Six experiments examined the factors that influence transfer for related texts. Transfer was indicated by increases in the reading speed and/or accuracy of reading a second text, following reading of different first texts. In Experiments 1-4, the first texts were related to the second by overlap in words only, in content only, in words and content or in neither words nor content. Results indicated that the extent to which readers benefited from word or content overlap depended on the readers' skill and the difficulty of the text. Children who read texts that were easy for them showed transfer only when pairs of stories shared content. However, when children read stories that were difficult for them, they also showed transfer when words alone were shared. In Experiment 5 children were given scrambled text to determine the effect of simple exposure to words without meaningful context. Reading scrambled words benefited only poor readers who were reading text that was difficult for them. In Experiment 6 the reading transfer of adults who read either a scrambled or a normal text was examined. Adults who were good readers benefited only when both texts were normal, as found by Levy and Burns (1990). However, when adults who were poor readers were given difficult texts, they benefited from prior exposure to the words of a text even when they were scrambled, as found by Carr, Brown and Charalambous (1989). The results are discussed in terms of how texts are represented in memory and retrieved to produce transfer.

abstract: Doctor of Philosophy (PhD)


title: CRYSTAL CHEMISTRY OF THE CLINO-AMPHIBOLES

contributor:
Grundy, Douglas H.
Geology

abstract: Doctor of Philosophy (PhD)


title: The Character and Role of Bohort in the Vulgate Cycle

contributor:
West, G. D.
French

subject: French and Francophone Language and Literature

abstract: Bohort's importance in the Vulgate Cycle has been dealt with to some extent in all the critical works but no real attempt has been made to turn this into a comprehensive study. Thus I have attempted in the following pages to tackle this character in all the romances in which he appears in the Vulgate Cycle and to establish his importance, as I firmly believe that he contributes in a very big way to these romances. His development as a character has been closely followed by analyzing his worth as chivalrous Knight of the Round Table and by examining his relationships with other important characters of the Vulgate Cycle, especially his cousin Lancelot. In addition, the study has also served as an attempt to try and determine the authorship of the Vulgate Cycle. This was perhaps the most intriguing part of the research and it was extremely difficult to arrive at any sort of a coherent conclusion. I tried to determine the authorship by examining the consistency in the presentation of Bohort and I tend to believe that more than one author was responsible for the compilation of the Vulgate Cycle. It does seem though, that this team of authors could have been inspired by a plan laid out by a single person.

abstract: Master of Arts (MA)


title: Hydrogen shift isomers of pyridine and other N-heterocycles: A tandem mass spectrometry study

contributor:
Terlouw, Johan K.
Chemistry

subject: Chemistry Chemistry

abstract: Ionic and neutral hydrogen shift isomers of common nitrogen containing heterocycles, such as pyridine, have been generated and identified as stable species in the gas phase. The ionic isomers could be obtained by dissociative electron ionization of carefully chosen precursor molecules. Their structure characterization could be realized using tandem mass spectrometry based techniques. Not only conventional metastable ion (MI), collision-induced dissociation (CID) and neutralization-reionization (NR) techniques were used but also the novel hybrid techniques, CID/CID and NR/CID. The use of deuterium labelled isotopomers and quantum chemical calculations formed an essential component in the interpretation of the results. The neutral hydrogen shift isomers are ylides, carbenes or betaines. Such species are frequently invoked as key intermediates in synthetic and metabolic pathways but their high reactivity in bimolecular reactions often precludes their identification in condensed phases. However, in the dilute gas phase of the mass spectrometer, where intermolecular reactions do not occur, the structure and intrinsic stability of such species may be examined. The mass spectrometric technique of neutralization-reionization (NR) is ideally suited for this purpose. In this technique fast moving beams of structurally well characterized ions are neutralized by charge exchange. The structures of the resulting neutrals are then probed with subsequent collisional ionization experiments. The thermodynamic stability of the various ionic hydrogen shift isomers appeared to be comparable to that of the parent isomer of conventional structure. A case in point is the pyridine ion Ia·+ for which ΔHf = 247 kcal/mol and whose hydrogen shift isomers pyridine-2-ylidene·+ (IIa·+ ), pyridine-3-ylidene·+ (IIb ·+ ) and pyridine-4-ylidene·+ ( IIc·+ ) have enthalpies of formation of 245, 244 and 242 kcal/mol. CID mass spectrometry provided a convenient and reliable tool for the characterization of these ions. The (distonic) ions IIa ·+ and IIb·+ but not IIc·+ could be subjected to reduction by single electron transfer in NR experiments. Intense "survivor" signals were obtained but collision experiments of the reionized neutrals (NR/CID) were required to establish the carbene structure of the neutral species generated. The experimental results concur with predictions from quantum chemical calculations that the neutral (singlet and triplet) and ionic isomers are minima on the potential energy surfaces which are separated by substantial (1,2-H shift) isomerization barriers.* The same strategy was used to probe the structure and stability of the H-shift isomers of neutral and ionic pyrazine (Ib·+ ), pyrimidine (Ic·+ ), thiazole (IIIa·+ ) and imidazole (IIIb ·+ ). Among the elusive neutral species identified are the ylides pyrazine-2-ylidene, pyrimidine-2-ylidene, pyrimidine-4-ylidene, thiazol-2-ylidene, imidazol-2-ylidene and imidazol-4-ylidene and the betaine pyrazine-3-ylidene. Ab initio calculations on the potential energy surfaces confirm the experimental results but they also reveal that the pyrazine and pyrimidine systems feature additional isomers of comparable stabilities. The final component of this work deals with the decarbonylation reaction of ionized 2-acetylpyridine, 2-acetylpyrazine and 2-acetylthiazole. Multiple collision experiments were used to show that this reaction does not involve a methyl migration yielding the 2-methyl substituted heterocycle as proposed in the literature. The product ions generated are the 2-methylene heterocycles, ionized 2-methylene-1,2-dihydropyridine, 2-methylene-1,2-dihydropyrazine, and 2-methylene-2,3-dihydrothiazole, suggesting that the decarbonylation involves a 1,4-H shift followed by an ipso substitution. NR/CID mass spectrometry was used to establish that the neutral counterparts of the ionized decarbonylation products retain their structural integrity in the rarefied gas phase. *Please refer to dissertation for diagrams.

abstract: Doctor of Philosophy (PhD)


title: Measurements of In Situ Production of Carbon-14 in Silicon Dioxide Production Rates and Cross-sections

contributor:
Kuehner, J.A.
Southon, J.R.

subject: Chemistry

abstract: The development of a technique for the extraction of ¹⁴c extraction technique and the ¹⁴c Accelerator Mass Spectrometer detection technique were applied to the measurements reported in this work. Samples of quartz chips were irradiated with neutrons produced by a 20 MeV tritium beam interacting with a deuterated Ti foil target. This irradiation permitted the first measurement of the ¹⁶o(n,2pn)¹⁴c cross section at 35 MeV for which a value of 16±3 mb was found. Two stacks of quartz plates were irradiated with 63 MeV protons. The measurement of the ¹⁶o(p,3p)¹⁴c cross section at several energies below 63 MeV are presented. The ¹⁴c in-situ produced was measured in seven obsidian rock samples. In four cases the values obtained agree with the calculated production rate of 0.19±0.05 atoms Kg⁻¹ min⁻¹ at 46º geomagnetic latitude and 640 g cm⁻².

abstract: Doctor of Philosophy (PhD)


title: Automated Detection of Treatment Responses with Cardiac Positron Tomography

contributor:
Nahmias, C.
Electrical and Computer Engineering

subject:
Electrical and Computer Engineering
Electrical and Computer Engineering

abstract:
The physiology of the muscle of the heart (myocardium) can be studied regionally in the living body using positron tomographic techniques. Compounds are labelled with a positron emitting isotope, administered into the circulation, and their distribution in the body is measured with a positron tomograph. This enables the rates of myocardial blood flow and substrate metabolism to be measured regionally in the myocardium of the left ventricle. The accuracy and precision of these measurements are estimated to range from 2% to 15% in a given individual. Much of this variability is due to normal changes in physiological state, or to measurement noise associated with counting statistics. However, additional variability is associated with manual processing, which typically involves specification of the left ventricular myocardium of interest using an interactive visual display. An automated technique of analysis can remove this source of variance, and enable an unbiased evaluation of changes in response to the treatment of heart disease. Results can then be compared objectively between population samples or in single subjects studied under different treatment conditions. By performing appropriate statistical comparisons, a large volume of data is compressed into a form which can be interpreted in an efficient manner.

An automated analysis technique is developed to remove the variability associated with manual processing. Reduction of the measurement variability increases the statistical power to detect physiological changes in the myocardium in different states of health and disease. The position and angular orientation of the left ventricle is determined directly from the measured dataset, so that the regional measurements can be analysed and presented in a standard format. The time course of radioactivity is determined for several hundred volume elements within the left ventricular myocardium, and for a blood region positioned in the ventricular cavity. Depending on the labelled compound and study protocol, various measures of myocardial physiology are computed from these two basic measurements. A technique is developed to compare treatment changes in physiology between population samples, by segmenting equivalent functional tissue regions from the left ventricular myocardium of the sample subjects. A method is also developed to evaluate the statistical significance of changes in single subjects, which may be useful to determine individual clinical responses to treatments. Comprehensive quality assurance outputs are generated, and are used to verify the analysis of all cardiac studies.

The performance of the method was determined using cardiac phantom and human data. The position and angular orientation of the left ventricle were determined to within 2±2 mm and 3±3 degrees of the true values respectively. The detection of treatment changes in a population sample was demonstrated using measurements of myocardial blood flow with ¹³N-labelled ammonia. An increase in blood flow to diseased (ischemic) myocardium in response to nitroglycerin was demonstrated using a quantitative automated approach: a highly significant (p=0.01) difference of 16 ml/min/dg (20% of normal) was detected in a sample group of 14 subjects. The performance of the single subject analysis was verified by measuring the rate at which significant changes occured by chance, which was equal to the theoretical false positive rate. In an individual from the population sample, a significant increase (p=0.001) in myocardial blood flow of approximately 30% was detected in a region of known ischemia, in response to treatment with nitroglycerin. The statistical tools developed in this work can also be used to determine other sources of measurement variability. Reduction of these effects will increase further the power of positron tomography to evaluate objectively the clinical effects and mechanisms of action of cardiac treatments in health and disease.

abstract: Doctor of Philosophy (PhD)


title: Preparation and characterization of pore-filled cation-exchange membranes

contributor:
Childs, Ronald F.
Chemistry

subject: Chemistry Chemistry

abstract: Pore-filled cation-exchange membranes containing poly(styrene-sulfonic acid) have been prepared by thermally induced free radical polymerization of polystyrene and divinylbenzene (DVB) in the pores of a polyethylene (PE) microporous membrane followed by sulfonation of the incorporated poly(styrene-DVB). The mass increase of poly(styrene-DVB) incorporated in the PE substrate membrane can be controlled from 0 to approximately 600%. The degree of sulfonation ranges from 45% to 85% of the theoretical value calculated based on the mono-sulfonation of the incorporated poly(styrene-DVB). The formation of sulfones was been detected by Fourier transform infrared (FTIR). The Energy dispersive X-ray (EDX) spectroscopy, scanning electron microscope (SEM), and FTIR spectra show that the poly(styrene-sulfonic acid) incorporated is evenly distributed in the pores throughout the membranes. The membrane dimensions were examined during various manipulations, such as temperature and solvent, degree of incorporation of poly(styrene-DVB). These pore-filled membranes were characterized including ion-exchange capacity, ion-exchange concentration, water content, thickness, area electrical resistance, and transport number. These membranes have high water contents (up to 75%), ion-exchange capacities (up to 5.60 meq/g), and ion-exchange concentrations (up to 7.3 eq/kg of water). The electrical resistance of the membranes were found to be lower than 1.0 ohm·cm2 . The counter-ion (Na+ ) transport numbers were determined by an electromotive force (EMF) method and were found to range from 0.80 to 0.96. The cation-exchange membranes have been tested for the separation of sodium hydroxide and salts by diffusion dialysis. The membranes were capable of separating the base and salts in diffusion dialysis. The results have been discussed in terms of the different transport processes for sodium hydroxide and the salt. The membranes are capable of rejecting sodium chloride and separating NaCl/MgCl2 mixed solute solutions in pressure-driven processes. It was found that their rejections to NaCl were high but their fluxes were low. The effects of salt concentration on fluxes and rejections were determined. Negative rejections of sodium ions were observed for NaCl/MgCl2 mixed solute solutions. The negative cation rejection can be understood in terms of the combination effect of Donnan exclusion of the cation-exchange membranes and the diffusivity of the mobile ionic species in the pressure-driven processes. The results obtained in this work are consistent with the recent studies at McMaster University. It clearly demonstrated that gel polymer concentration within the pores is a crucial factor on membrane permeability. The findings of this work verified the pore-filled model developed at McMaster University. The work conducted in this thesis extends the understanding of properties and performance of polyelectrolyte-filled membranes for nanofiltration applications.

abstract: Doctor of Philosophy (PhD)


title: Characterization of homoserine dehydrogenase from Saccharomyces cerevisiae: An antifungal target

contributor:
Wright, Gerard D.
Biochemistry

subject: Biochemistry Biochemistry

abstract: Homoserine dehydrogenase (HSD), the third enzyme in the aspartate biosynthetic pathway producing isoleucine, methionine and threonine, is an important new antifungal target. Previously, (S )-2-amino-4-oxo-5-hydroxypentanoic acid (RI-331), an antifungal compound, demonstrated inhibitory activity against HSD from Saccharomyces cerevisiae . This pathway is an excellent target for the development of new non-toxic antifungal drugs, as it is absent in mammals. In order to design effective inhibitors of fungal HSD, a full kinetic and mechanistic characterization of this enzyme was required. Consequently, HSD from a model fungus, S. cerevisiae , was examined. Surprisingly, yeast HSD was able to bind either cofactor, NADPH or NADH, with high affinity. Product inhibition studies suggested that yeast HSD preferentially binds the nicotinamide cofactor before the amino acid substrate and releases the cofactor last. The inhibition pattern of the newly discovered HSD inhibitor, H-(1,2,4-triazol-3-yl)- D,L -alanine, was consistent with the proposed substrate binding order. In addition, viscosity and kinetic isotope experiments provided evidence for a fast catalytic step and a rate-limiting NAD(P)+ release during HSD catalysis. The stereochemistry of hydride transfer was determined to be from the pro-S C-4 nicotinamide hydrogen by kinetic isotope effects. Chemical modification experiments and site-directed mutagenesis of HSD determined that histidine 309 is an important residue in HSD catalysis. However, the recently solved HSD X-ray structure revealed that His309 may, in fact, be solely important in HSD dimerization. On the other hand, pH studies demonstrated that basic residues are involved primarily in substrate binding, in agreement with lysine residues discovered in the active site of the HSD structure. Lastly, RI-331 demonstrated many properties of a mechanism-based inactivator. This compound appears to form an adduct with NAD(P)+ in an HSD-dependent manner, thereby producing a tight-binding transition-state analog of yeast HSD. These studies will provide the necessary foundation for the development of a new class of antifungal drugs targeting amino acid biosynthesis.

abstract: Doctor of Philosophy (PhD)


title: Performance Assessment & Ductility Enhancement of Beams Subjected to Cyclic Loading

contributor:
Korol, R.M.
Civil Engineering

subject:
Civil Engineering
Civil Engineering

abstract:
Structural frames designed or proportioned to resist seismic forces, must possess adequate ductility to redistribute internal forces or have needed energy absorbing capability. This research investigation touches on a number of aspects that deal with or relate to the above characteristics, while the principal aim is to assess and compare the rotation capacity and energy absorption of locally web stiffened beams with unstiffened beams.

An approach which allows for the prediction of the initiation of local buckling in the design of wide-flanged beams under moment gradient, is first presented. The method described represents a refined moment-rotation model that includes the effects of strain hardening. This same approach helps define more accurately the appropriate slenderness limits of a beam's plate-elements in relation to the required rotation capacity at maximum moment.

The study then addresses the interaction effects of a steel member's plate slenderness values and its lateral slenderness on rotation capacity at ultimate deformation. It is shown that members with slenderness values close to the limits specified by codes of practice may not be able to redistribute moments adequately under seismic loading.

To further ascertain and assess the ductility and energy dissipation capabilities of W-shaped beams, a series of test specimens subjected to monotonic and quasi-static cyclic loading was conducted. The specimens were meant to represent beams in ductile moment resisting frames undergoing cyclic lateral loads. Of direct relevance to seismically designed moment resisting steel frames, the experimental results of this research effort clearly highlight the superiority of herring-bone style stiffened specimens over unstiffened specimens. To provide further supporting evidence, as well as insights into the behaviour of herring-bone stiffeners, an inelastic large deformation analytical study was undertaken using cubic-quadratic shell finite elements. This work allowed a parametric study to be undertaken on the effects of stiffener thickness on strength and ductility properties. Based on these, and the experimental results, preliminary design guidelines have been proposed. Another important objective was to assess and document the strength and energy deterioration occurring under conditions of low cycle fatigue and which involve local buckling.

The results of a series of W-shaped test specimens subjected to fatigue type of loading under constant amplitude are presented. This work has permitted strength and energy deterioration and damage models to be developed for the W-shape steel beams. A generalized model which uses plate slenderness values together with lateral slenderness is proposed for predicting the rate in strength deterioration per reversal and cumulative damage after a given number of reversals.

The research investigation concludes with a review of some of the concepts used in damage assessment; simple damage parameters such as ductility ratio and realistic mathematical models reflecting the deterioration of steel beams due to maximum response, and, dissipated energy are then discussed. Damage models are then presented that combine maximum response with repeated effects in low-cycle fatigue loading. The proposed models calibrated through the use of cyclic tests on steel beams, are then used to yield deterministic parameters that predict adequate ductility values for steel beams under cyclic loading. This phase of the work was completed by having the damage models incorporated into a non-linear dynamic analysis of a sample building and ends with the recommendation of employing a new "adequate ductility" design parameter.

abstract: Doctor of Philosophy (PhD)


title: Secondary Flow in a Two-Dimensional Cascade of High Turning Angle Turbine Blades

contributor:
T., J. H.
Mechanical Engineering

subject:
Mechanical Engineering
Mechanical Engineering

abstract:
Modern trends in gas turbine design have been geared to producing a compact high work output engine as a power unit. To achieve this, the turbine rotor must be comprised of high turning angle blades. Secondary flow has always accounted for a major portion of the losses within a blade row and high turning angle blades tend to reinforce these losses. A review of the current literature on secondary flows shows that there is a void of data for two-dimensional high turning angle turbine blade cascades.

The object of this study was to construct and experiment upon a large scale two-dimensional high turning angle turbine blade cascade. Each of the four blades within the cascade had a chord and span of 214 mm and 188.5 mm respectively. The overall test rig was an open circuit wind tunnel which was operated at a Reynolds number of 3.68 X 10⁵ (based on the blade chord) which corresponded to a mean blade inlet velocity VI of 26.5 m/s (87 ft/s). The rig was designed with the facility to adjust the inlet flow in the pitchwise direction to ensure periodicity. Suction chambers were installed on the inlet channel endwalls to control the boundary layers and hence observe their effect on the measured secondary losses. The flow parameters were measured and recorded at the inlet bellmouth throat, at the inlet and the exit from the cascade and at a distance of 1.5C in the streamwise direction from the cascade exit.

A blade passage surface static pressure distribution is presented and the exit flow parameters are given in the form of contour of total pressure loss coefficients and static pressure coefficients. The spanwise distribution of pitchwise averaged flow parameters is given and the measured losses are reported and compared with existing correlations. The measured losses were found to be significantly lower than those predicted by these correlations.

abstract: Master of Engineering (ME)


title: Symbol tales: Paths towards the creation of a saint

contributor:
Badone, Ellen E.F.
Religious Studies

subject: Religion Religion

abstract: In "Symbol Tales: Paths Towards the Creation of a Saint", I discuss Catholic Pueblo women's devotion to Blessed Kateri Tekakwitha, a seventeenth century Mohawk convert turned folk saint. Between 1996 and 1998, I conducted extensive ethnographic fieldwork in the Pueblos of New Mexico, including Isleta, Jemez, Laguna, Acoma, and San Juan, as well as in Mescalero, on the Navajo Nation, and in the urban center of Albuquerque. This book is interdisciplinary and uses the methodologies and new writing styles of interpretive and reflexive anthropology to focus on the populist dimensions of saint-making, the ethnotheology of sainthood, devotional narratives, inculturation, miracle discourses, and Native American identity within the post-conciliar Catholic Church. I argue that the "blankness" and silence of Kateri in the official hagiographic tradition allows for both popular theological creativity in the imaginative space of the devotional narratives, and the formation of new social and devotional groups such as local "Kateri Circles" and the multi-tribal national annual Tekakwitha Conference. Finally, I explore the emergence of a broad Catholic pan-Indianism centred around the symbolic figure of Kateri Tekakwitha.

abstract: Doctor of Philosophy (PhD)


title: Well-posedness and Wavelet-based Approximations for Hypersingular Integral Equations

contributor:
Peirce, Anthony
Mathematics

subject: Mathematics Mathematics

abstract:
The main object of this thesis is to investigate the hypersingular integral equations which arise in Boundary Element (BE) models for crack problems. Although the associated hypersingular integrals are not defined in the usual sense, we interpret them in terms of Hadamard finite part integral operators or as pseudo-differential operators in the distribution sense.

By introducing weighted Sobolev spaces to regularize the equations, we have proved the well-posedness for such hypersingular integral equations. Global error estimates are obtained in the thesis.

A new approach to the numerical solution of the hypersingular equations based on the recently developed theory of wavelets is presented. Rather than applying wavelet bases directly to obtain new discretizations, we exploit the wavelet bases to obtain more efficient solution algorithms for the more classical discretizations. We discretize the hypersingular integral equation using the piecewise polynomial collocation method. The discrete wavelet transform is then used for the resulting dense algebraic system. This procedure involves O(N²) operations and leads to a sparse matrix problem. Solving this sparse matrix system requires only O(N log² N) operations whereas O(N³) operations are required for the traditional. BE method. Exploiting an indexed storage structure, we reduce the memory requirements from O(N²) to O(N log N) words. Furthermore, the method is applicable to all operator or matrix (with arbitrary geometries) problems as long as the operator or matrix possesses only a finite number of singularities in some rows or columns.

We demonstrate that the wavelet-based method can be extended to higher dimensional integral equation problems because these equations can also be discretized by the piecewise polynomial collocation approximation.

abstract: Doctor of Philosophy (PhD)


title: Conditional Immunomodulation

contributor:
Siegel, S.
Psychology

subject:
Psychiatry and Psychology
Psychiatry and Psychology

abstract:
Interest in central nervous-immune system interactions was inspired largely by the work on conditional immunomodulation (Ader and Cohen, 1975, 1985). Ader and Cohen (1975) reported that rats trained such that a taste cue (saccharine, SAC) predicted an injection of an immunosuppressant (cyclophosphamide, CY) subsequently exhibited a conditional immunosuppression in response to SAC alone.

Experiments 1-3 were designed to evaluate reports of conditional immunosuppression after training with SAC and CY. Rats received either one or three training sessions in which SAC presentation was followed by CY injection. Upon reexposure to the SAC, antibody formation to sheep red blood cells was assessed. Rats which were trained with SAC and CY had antibody titers that did not differ from saline controls, which rats which SAC and CY in a nonpredictive manner had suppressed antibody titers.

Experiments 4 and 5 assessed the effectiveness of environmental and drug state cues in signalling CY injections. In Experiments 4 and 5, the effect of training was to attenuate the unconditional immunosuppression produced by the CY.

Experiments 6 and 7 further assessed conditioning with pentobarbital predicting CY. After conditioning, some animals were rested until the residual effects of the CY had dissipated. When reexposed to the pentobarbital after this period, these animals had antibody titers that were significantly elevated above those of animals that never received the CY. Other animals received seven pentobarbital injections during the rest period. These animals demonstrated extinction of the conditioned response.

Experiment 8 assessed the effectivness of conditioning when the unconditional stimulus was antigenic rather than pharmacologic. After sensitization, rats received antigen injections paired with an environmental cue. Upon reexposure to the cue, trained rats had increased levels of rat mast cell protease II in their serum. As this protease is found only in mucosal mast cells, these results suggest that mucosal mast cells may be activated by a cue for antigen.

In a final experiment, physiological correlates of conditional mast cell activity were examined. Ussing chambers were employed to assess responsivity of intestinal epithelium after exposure to a cue for antigen. Results indicated that sensitivity to in vitro antigen was altered in rats exposed to a cue for antigen. These results, and those of the previous studies, support the hypothesis that the nervous and immune systems communicate, and that this communication may be functionally important.

abstract: Doctor of Philosophy (PhD)


title: The urban domestic baths of Roman Africa

contributor:
Dunbabin, K.M.D.
Classics

subject: Classics Classics

abstract: This thesis examines the baths of the domus in Roman Africa. Private baths have long been recognized as an aspect of Roman domestic architecture, whether belonging to the country residence (villa ) or urban residence (domus ) of the wealthy. However, despite the numerous examples of these baths uncovered by archaeological investigation, and in disparate regions of the Roman world, they are not at all understood. It has generally been considered enough to recognize that they are usually small, and their association with the domestic architecture of the rich suggests that these baths are a luxury, and presumably a status symbol. The domestic urban baths of Roman Africa have been selected since they form a geographically restricted group in an area with a well-developed public bathing tradition. The domestic baths are also found in contexts datable throughout the period of Roman provincial control of North Africa. Since the remains are nearly all the discoveries of early excavation technique, and incompletely published, a primary goal is the clarification of their layout and installations. Forty-three examples are identified. They are found in the houses of the wealthy, although the differences between the houses show that many must have belonged to the comfortably off, and only a few to the very wealthiest inhabitants. The baths show variations in size, number of rooms and pools, and decoration, but they follow a basic and practical arrangement. They all contain a full set of bathing rooms, catering to a complete bathing ritual built around a communal bathing routine. An interesting arrangement in some baths permits bathers to enter directly from the street, which suggests that they are not entirely private in use. The differences between the examples illustrate that a variety of reasons prompted the addition of baths to a domus , precluding a common interpretation for the role of domestic baths in urban society in Roman Africa.

abstract: Doctor of Philosophy (PhD)


title: Sterically Demanding Organometallic Complexes Containing Multiple Clusters or Polyphenylated Ligands

contributor:
McGlinchey, M. J.
Chemistry

subject: Chemistry Chemistry

abstract:
Sterically demanding organometallic complexes, in which bulky clusters or large polyphenylated groups are incorporated, possess interesting structural character as well as molecular dynamics.

Trichloroacetate esters, p-C₆H₄(O₂C-CCI₃)₂ and C(CH₂-O₂C-CCI₃)4, can be utilized as templates in building multi-cobalt cluster systems such as p-C₆H₄(O₂C-CCo₃(CO)₉)₂ and C[CH₂-O₂C-CCo₃(CO)₉]₃(CH₂-O₂C-CCI₃). The crystal structure of C(CH₂-O₂C-CCI₃)₄ has been obtained and a molecular modelling study was performed on the tetra-cluster C[CH₂-O₂C-CCo₃(CO)₉]₄.

The 1,1,1-trichloroacetylacetonate complexes of Co(II), Co(IIl), or AI(III) can also be used as templates in the preparation of multi-cluster molecules by reaction with CO₂(CO)₈. The uncomplexed cluster ligand, CH₃C(O)CHC(OH)CCo₃(CO)₉, was structurally characterized. Its direction of enolization was studied by EHMO (Extended Huckel Molecular Orbital) calculations. The tendency to enolize is also found in (benzoylacetone)Cr(CO)₃ which was characterized by x-ray crystallography.

The Diels-Alder reaction of tetraphenylcyclopentadienone (tetracyclone) with triphenylcyclopropene yields a ketone adduct, C₇Ph₇HCO, with an endo hydrogen at the methine carbon; thermal elimanation of CO produces heptaphenylcycloheptatriene, C₇Ph₇H, a sterically crowded polyaryl system. This initially formed conformer with a pseudo-equatorial phenyl substituent at the sp³ position is sterically hindered and undergoes a conformational flip which allows the phenyl group to occupy the favored pseudoaxial site. However, the remaining phenyls are sterically encumbered and slowed rotation of these rings can be monitored by ¹H and ¹³C NMR spectroscopy. The intermediacy of the conformer is shown by the formation of isomers of C₇(p-tolyl)₂Ph₅H, arising via a series of [1,5] hydrogen shifts that are possible only for this conformer. Similarly, use of 2,5-dimethyl-3,4-diphenyl-cyclopentadienone yields C₇Me₂Ph₅H in which [1,5] hydrogen shifts also occur.

The heptaphenyltropylium ion, C₇Ph₇⁺Brˉ or C₇Ph₇⁺BF₄ˉ, has a planar central seven membered ring. The C₇Ph₇ˉK⁺ anion, which is prepared from C₇Ph₇⁺Brˉ and potassium metal, reacts with Me₃SnCI and SiMe₂HCI to form σ-bonded derivatives, C₇Ph₇-SnMe₃ and C₇Ph₇-SiMe₂H.

The reaction of Cr(CO)₆ with C₇Ph₇H, or C₇Me₂Ph₅H, leads to incorporation of a Cr(CO)₃ group on a peripheral phenyl ring rather than on the seven-membered ring. However, the tricyclic ketone, C₇Ph₇HCO, which is the precursor to C₇Ph₇H, reacts with Mo(CO)₆ to give the π-allyl complex, (η⁵-C₅Ph₄OH)Mo(CO)₂(η³-C₃Ph₃H₂), in which the triphenylcyclopropene ring has been opened as seen in its x-ray crystal structure.

abstract: Doctor of Philosophy (PhD)


title: Optical Measurements of Magnetically-Aligned Asbestos Fibers

contributor:
Ballik, E.A.
Physics

subject: Physics Physics

abstract:
The magnetic-alignment behaviour of asbestos fibers suspended in water was studied. As the magnetic field rotates, with the lag increasing as the rotation rate increases. A theoretical model describing fiber behaviour was developed. Experiments measuring the phase lag of individual fibers, experiencing torques to the order of 10^18 Newton-meters were in excellent agreement with the model. For an unknown fiber the phase lag measurement will give the ratio of the length to radius of the fiber. For a known fiber, the cross-sectional size and shape can be determined.

This research was undertaken with the intention of laying down the groundwork from which an automatic instrument for monitoring asbestos exposure could be made. Initial investigations involved filtering a liquid dispersion in a one Tesla magnetic-field. The filter contained permanently aligned fibers. The fiber was made transparent and scattered-light measurements were made relative to the initial magnetic field direction were made. Subsequent research focussed on mesuring light scattered by fibers suspended in water while the fibers followed a rotating magnetic-field. The latter technique proved far more sensitive, being able to detect fiber concentrations of the order of one million fibers per liter with relatively simple equipment. On a mass basis, this sensitivity corresponds to one part in 10^10. The method did not have the problems associated with the filter itself. Equally important, there is the potential to obtain fiber size information.

abstract: Doctor of Philosophy (PhD)


title: Dynamics, Simulation and Control of Flexible Robotic Systems

contributor:
Dokainish, Mohamed A.
Mansour, William M.
Mechanical Engineering

abstract:
This research develops a new methodology for the control of two link flexible arms. The methodology is referred to here as "Nonlinear Integrated Tabular" NIT Control. Starting with a new trajectory, the inverse kinematic problem is solved and adequate algorithms are presented to evaluate the commanding voltages to guarantee that the wrist point will track the desired trajectory. Continuous and discontinuous paths are tried with models which were developed to account for the flexibility in the joints and the flexibility in the links. Lagrange's equation and finite element formulation were used to construct realistic models. Computer simulations were conducted to assess the control qualities for tracking using NIT. The accuracy, smoothness as well as the levels of the command signals during tracking were quantified to serve as criteria to evaluate the quality of tracking.

A number of classical controls were developed and applied to the elbow arm to compare NIT with the current available approaches. A proportional plus derivative plus gravity, a feedback linearization as well as a VEE-MOD-VEE controllers were tried. It was shown that NIT compares well with the most successful conventional methods. In addition, it was found to offer simple, smooth, robust, computationally economic controls. NIT compares well with the majority of the conventional methods.

An experimental setup was constructed with the objectives of verifying the analytical predictions. It was built in a modular form to allow continuity of research in this area at McMaster's laboratories. Great care and long hours were spent in the design, fabrication, assembly, debugging of the hardware for the mechanical parts. The setup is referred to here as FLEXROD. The up-to-date technologies available today were implemented in the design of FLEXROD which include Harmonic Drives for speed reduction and transputers for the controller. Enormous efforts went into streamlining the software and in developing the interfaces between the sensory system and the controller. Experiments were conducted to validate the transient dynamics of the elbow arm when the motors are brought to a sudden stop by applying the brakes simultaneously. Reasonable agreement was found between the analysis and the experiment. The thesis is concluded with recommendations for future research in this area to implement and develop NIT using FLEXROD.

abstract: Doctor of Philosophy (PhD)


title: Pistol Eloquence: The Literary Evolution of the Criminal and Detective in the Eighteenth- and Nineteenth-Century British Novel and Its Contribution to the Advent of Modern Crime and Detective Fiction

contributor:
Aziz, M.
English

subject:
English Language and Literature
English Language and Literature

abstract:
Crime and detective fiction are modern genres that cannot be considered as twentieth-century manifestations of an earlier genre. Quite simply, there is no evidence of a sustained development of a genre primarily concerned with the criminal or detective in the eighteenth and nineteenth centuries. The criminal and the detective develop little in this period as characters interpreted according to previous writers' treatment of them. They appear as important characters in major stages of the novel's development, such as the picaresque, social and sensation novels, primarily as a means of illustrating predominant themes evident in the novel: the picaresque novel's criticism of the whole of society, the social novel's criticism of specific problems in the judicial system and society, and the sensation novel's portrayal of the thrilling and abnormal.

As these critical and thematic concerns evolved in the development of the novel, the characters of the criminal and the detective also evolved. The evolution of both characters can be categorized in a succession of five stages that represent the predominant themes with which they are associated in considering literary trends in the eighteenth and nineteenth-century novel: the picaresque, the judicial, the social, the domestic and the deviant stage of their literary evolution. In tracing this evolution, the detective is considered as part of the literary evolution of the criminal because he evolves in a manner similar to that of the criminal, but, chronologically, his evolution is later than that of the criminal.

The stages of this evolution are best represented by novels that give an important place to the criminal or detective and by novelists who displayed a significant interest in the criminal or detective, such as Daniel Defoe, Henry Fielding, William Godwin, Edward Bulwer-Lytton, Charles Dickens, and Wilkie Collins. An examination of these novelists, and other writers, and their works illustrates a reduction in the thematic importance of the criminal in the course of the five stages of his evolution: he evolves from being a critic of society, to being merely a victim who is representative of society's problems, and, finally, to being a deviant who neither criticizes nor represents society. Only at this final stage, when presented as having little or no relationship to the judicial system and society, could the criminal and the detective warrant genres of their own in which they are not treated as part of a critical concern or a literary trend, but as characters of interest in and for themselves. They became important for the pleasure they gave rather than for the critical insights they offered; hence, modern crime and detective fiction was born.

abstract: Doctor of Philosophy (PhD)


title: The Optical Properties of Pyrochlore Oxides R₂Mo₂O₇_δ (R: Sm, Gd, and Ho), The Heavy-Fermion UNi₂Al₃, and The Organic Conductor (TMTSF)₂ClO₄

contributor:
Timusk, T.
Physics

subject: Physics Physics

abstract:
The temperature dependence of the reflectance of the spin-glass materials R₂Mo₂O₇_δ (R: Sm, Gd, and Ho) has been measured for frequencies from 40 to 40,000 cmˉ¹. The real part of the AC conductivity of Sm₂Mo₂O₇_δ, derived from Krarners-Kronig analysis, indicates a Drude-like behavior as the temperature is lowered. Between 150 and 40 K the scattering rate shows a sharp drop which is attributed to the scattering of conduction electrons by short-range ordered moments of the Mo ions. Below the spin-glass transition temperature Tf(≅40 K) the scattering rate saturates due to the freezing out of the moments. Gd₂Mo₂O₇_δ behaves like a poor metal at room temperature, but at low temperatures shows a linear increase in the conductivity for frequencies up to 400 cmˉ¹ suggesting a localized hoping conductivity. The localization remains in the spin-glass state for T

The optical properties of the new heavy-fermion superconductor UNi₂Al₃ have been investigated at temperatures between 10 and 300 K using reflectance spectroscopy. A characteristic energy scale (ωc≅90 cmˉ¹), with almost the same value as the characteristic temperature T₀ derived from measurements of the DC resistivity and susceptibility, is obtained from the optical conductivity. At high temperatures (T>T₀), this scale represents the energy gap between the ground and excited level that results from the crystal-field splitting of the 5f² (J=4) level of the tetravalent uranium ion. In the low-temperature coherent region (T

The polarized optical reflectance of the quasi-one-dimensional organic conductor (TMTSF)₂ClO₄ has been measured along the chain axis from the far-infrared (~8 meV) to the visible (~1 eV) at temperatures between 10 and 300 K. The real part of the optical conductivity shows that a gap (2Δ≅21 meV) develops in the conductivity at low temperatures that may be related to the long-range ordering of SDW found in the NMR measurement for T < Tc³ᴰ≅25 K. Precursors of the SDW gap (pseudogap) that may result from the one-dimensional SDW fluctuations are visible as high as 100 K and are also indicated by both the temperature dependent integrated conductivity spectral weight between 2Δ and 1000 cmˉ¹ and intensity of the phase phonons. Our results suggest that the very high DC conductivity of this material at low temperatures is carried by a narrow mode at zero frequency. This narrow mode has been supported by both the fitting of the reflectance data below 60 K to a Drude term plus the other terms and the large negative values in ε₁(ω) at low frequencies. The spectral weight associated with this narrow mode decreases sharply with increasing temperature which is similar to the temperature dependence of the spectral weight of the induced phonons found in far-infrared. This indicates that both the narrow zero-frequency mode and the induced phonons have the same collective-excitation origin in this quasi-one-dimensional material.

abstract: Doctor of Philosophy (PhD)


title: Memory for Luminance: An exploration of a bias in judgements of discrete changes in luminance

contributor:
Tipper, S.P.
Psychology

subject: Psychology Psychology

abstract:
The series of nine experiments in this thesis describes an exploration of what we believe to be a new empirical effect for luminance judgements. The basic effect is that judgements about discrete changes in luminance are biased in the direction of previous luminances. Along with an introductory chapter and a final chapter discussing overall conclusions, the nine experiments are arranged into three chapters, each of which addresses an hypothetical explanation of the effect.

In Chapter 2, the relationship between the luminance bias and representational momentum (RM) was examined. Experiment 1 demonstrated the basic RM effect using a common RM paradigm (E.g. Freyd & Finke, 1984), and showed that when subjects in a comparable experiment made luminance judgements, they showed data opposite to that predicted by the RM hypothesis. Experiment 2 showed that this qualitatively different pattern of data was not the result of time course differences. Experiment 3 showed that the effect of a manipulation which reduces or eliminates RM has a vary different effect on the luminance task. We conclude from these experiments that RM may not act on the dimension of luminance change, that this finding is important in light of current debates as to the function of RM, and that the luminance effect is worthy of further study in its own right.

In Chapter 3, we examined whether the luminance bias might be explained by either of two mechanisms which are argued to be the result of processes early in the visual system, namely the "ramp aftereffect" first reported by Antis (1967), and constancy. Because the ramp aftereffect is known not to transfer across retinal locations, Experiments 4 and 5 tested whether the luminance bias under investigation here does so. It does. Experiment 6 asked whether the size of the bias changes for dark items on a light background, as opposed to light items on a dark background, a manipulation which results in more robust lightness constancy (Jacobsen & Gilchrist, 1988b). It does not. We conclude that the luminance bias is not the result of these early perceptual mechanisms.

In Chapter 4, we asked whether the bias for luminance judgements is better characterized as stemming from the first item in the display, the most recent item in the display, or some average of all the displays. Experiments 7 and 8 manipulate the first and most recent items while holding the average luminance of the displays constant. Experiment 9 manipulated the average luminance of the displays, while holding the most recent item constant. The results suggest that the luminance bias is affected by the average luminance of the displays. This finding puts a constraint on potential models of this luminance bias.

The final chapter in the thesis discusses the conclusions to be drawn from the nine experiments. It argues that these findings suggest that representational momentum can only be observed for a subset of dimensions of change, contrary to current theory. It speculates on the physiological underpinnings of both RM and the luminance bias. It suggests that the luminance bias is better characterized as a memorial rather than a perceptual effect. Finally, it speculates on the possible adaptive value of this effect.

abstract: Doctor of Philosophy (PhD)


title: Harm reduction, human rights, and Canada's cannabis controversy

contributor:
Shaffir, W.B.
Sociology

subject: Sociology Sociology

abstract: This study examines today's dominant strategies of drug reform rhetoric from a social constructionist perspective, focusing specifically on the movement for marijuana law reform in the legal-political context of Canada. In the first chapter, recent developments in social problems theory are examined in terms of the ongoing debate among constructionists over the meaning of reality and "objectivity" in the human sciences. The second chapter outlines the methods of data collection and analysis, along with some of the problems I encountered, in a study of thirteen "public figures" variously connected and identified with the cannabis reform movement in Canada. A key rhetorical strategy employed by several of the reformers I interviewed--the strictly rational "harm reduction" approach to drug use and policy--is examined in the third chapter, wherein it is generally described as a preeminently pragmatic, public health response to the drug problem that seeks to reduce personal and societal harms due to drug (ab)use rather than prohibiting drug use per se. Despite steadfast resistance from status quo supporters, the harm reduction movement, emphasizing education and treatment over more punitive drug control measures, is increasingly recognized among analysts as a viable and pragmatic policy alternative to prohibition. Harm reduction options for cannabis focus primarily on lowering the cost to society of enforcing ineffective drug laws with resources that are clearly inadequate to deter widespread recreational use. By easing restrictions prohibiting simple possession and use of the drug, as long has been argued by several of the participants in this study (e.g., Solomon, Single, and Erickson 1983), even partial decriminalization in Canada would substantially lower the cost of enforcement and mitigate the personal impact of imposing criminal sanctions on users. In light of these claims, I discuss several cannabis control options aimed at reducing the harms due to overly punitive drug control measures. In addition, I examine a concern that is more commonly reserved for users of "hard drugs," that is the reduction of harm due to regular use. Harm reduction's claims to strict rationality notwithstanding, the movement has had difficulties influencing policy due to some key practical and political problems. (Abstract shortened by UMI.)

abstract: Doctor of Philosophy (PhD)


title: Angiogenesis and immune regulation in tumor gene therapy

contributor:
Gauldie, Jack
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: In our studies, we have used adenoviruses containing the genes for Angiostatin (Ad-Angiostatin) and IL-12 (Ad-IL12) for tumor therapy. The biological activity of the Ad-Angiostatin has been characterized using an artificial matrix which promotes the growth of blood vessels (Matrigel). We observed suppression of vessel growth in the Matrigel following treatment with Ad-Angiostatin demonstrating the inibitory activity of this virus. Treatment of growing tumor in mice with either Ad-Angiostatin or Ad-IL12 resulted in modest delays in tumor growth compared to tumors treated with viruses which did not contain any genes. Ad-IL-12 treatment also causes tumors to regress in a small fraction of the treated animals (13%). However, when used in combination, treatment with Ad-Angiostatin and Ad-IL12 resulted in tumor regression in 54% of the cases, a strong anti-tumor response by killer white blood cells, and the cured animals were resistant to further outgrowth of tumor. These results are the first to demonstrate the usefulness of combining angiogenesis inhibitors with cytokines using gene therapy. The rationale for this therapy is to limit the tumor size by attacking the vasculature with angiostatin, allowing the Interleukin-12 to activate killer white blood cells to respond against foreign products present in the tumor tissue. In this manner, the potential for the white blood cells to reject the tumor is increased as there is less tumor mass present. (Abstract shortened by UMI.)

abstract: Doctor of Philosophy (PhD)


title: Integrated Waste Management: A Knowledge Based Decision Support System Prototype for Developed and Developing Countries

contributor:
Baetz, Brian W.
Engineering

subject: Engineering Engineering

abstract:
A prototype knowledge-based decision support system was developed to compare the components and parameters of the inputs and wastes of different industries and determine the potentials for reuse, recycling or disposal and the treatments required for recycling or disposal. The specific number and the order of required treatments was termed a treatment train and was determined through exhaustive searching. The knowledge base included the input limits for each parameter and the formulae that define the parameters of the outputs for 25 treatments. The parameters depend upon the state of the waste and a total of 29 parameters were included. The system also determined the quantity of the secondary wastes produced by each treatment.

To test the system, inputs, products and wastes from four industries on the Point Lisas Industrial Estate, Trinidad were incorporated into the database. For the 73 wastes, the program produced over 4,600 treatment trains, with seven wastes which could not be treated to match an input or a standard. By selecting the treatment train which produced the lower volumes of secondary wastes, matching treatment trains for co-treatment and selecting the shorter trains, final options for treatment were determined. Economic data were not incorporated into the system, although a mechanism for such an incorporation has been included in the developed prototype.

This research provided the following contributions:

a) Development of a prototype knowledge based decision support system for determining all possible treatment options for successfully treating a waste for reuse, recycling or disposal;

b) Development of a model for selection of treatment options for each waste;

c) Incorporation of different types of wastes from different producers into the prototype;

d) Determination of the input limits and formulae to define outputs from treatments;

e) Development of an approach that considers the concerns of developing countries.

abstract: Doctor of Philosophy (PhD)


title: Two-Phase Flow-Induced Vibrations in a Heated Tube Bundle

contributor:
Weaver, David S.
Judd, Ross L.
Mechanical Engineering

abstract: The U-bend region of nuclear steam generators tube bundles have suffered from two-phase cross flow induced vibrations. Tubes in this region have experienced high amplitude vibrations leading to catastrophic failures. Turbulent buffeting and fluidelastic instability have been identified as the main causes. Previous investigations have focused on flow regime and two-phase flow damping ratio. However, tube bundles in steam generators have vapour generated on the surface of the tubes, which might affect the flow regime, void fraction distribution, turbulence levels and tube-flow interaction, all of which have the potential to change the tube vibration response. A cantilevered tube bundle made of electric cartridge heaters was built and tested in a Freon-11 flow loop. Tubes were arranged in a parallel triangular configuration with pitch to diameter ratio of 1.48. The bundle was exposed to two-phase cross flows consisting of different combinations of void from two sources, void generated upstream of the bundle and void generated at the surface of the tubes. Tube tip vibration response was measured optically and void fraction was measured by a gamma densitometry technique. It was found that the ratio of tube vibration amplitude in the transverse direction was reduced by a factor of 8 for void fraction generated at the surface of the tubes only, when compared to the response observed under the upstream only void generation case. The main explanation for this effect is a reduction in the correlation length of the turbulent buffeting forcing function. Theoretical calculations of the tube vibration response due to turbulent buffeting under the same experimental conditions predicted a similar reduction in tube amplitude. The void fraction for the fluidelastic instability threshold in the presence of tube bundle void fraction generation was higher than that for the upstream void fraction generation case. The first explanation of this difference is the level of turbulent buffeting forces to which the tube bundle is exposed. Increased values of turbulence will lower the void fraction for instability. The second explanation is related to the flow regime. In this study, it was clear that flow regime for bundle void generation was at all times bubbly and homogeneous, while the upstream void fraction generation cases showed a clear tendency to churn flow. A change in flow regime from bubbly to churn flow will produce the same effect as an increase in turbulence buffeting levels, and hence it seems difficult with the present knowledge to distinguish between the two causes. In as much as turbulence levels are related to flow regime, it is essential to have a clear knowledge of the flow regime in steam generators in order to predict the fluidelastic instability threshold of the tubes.

abstract: Doctor of Philosophy (PhD)


title: Tightening the Social Knot: Rousseau and the Politics of Imagination

contributor:
Simpson, Evan
Philosophy

subject: Philosophy Philosophy

abstract: Jean-Jacques Rousseau maintained that he was a consistent thinker, even if he presented his ideas in an unsystematic fashion. My work is a demonstration of the coherence of Rousseau's writing that highlights how his views on the nature and form of human imagination connect various aspects of his political philosophy. Moreover, by exploring his concept of imagination, it becomes clear that one of Rousseau's main philosophical preoccupations was the problem of social cooperation. In particular, Rousseau sought ways of controlling and directing human imagination in order to foster and nurture the emotions he thought central to harmonious social and political life. In the course of establishing my interpretation, I describe the relationship between imagination and emotional development as well as the role imagination plays in preserving social order. In the process I defend Rousseau from criticisms that see his position as favouring a narrow and restricted vision of human life and human community. Part of this effort includes a discussion of imagination as central to his model of political decision making and his ideal of citizenship. I conclude with a consideration of how an understanding of these issues provides a new perspective on Rousseau's views on the general will and personal autonomy.

abstract: Doctor of Philosophy (PhD)


title: The toxicology and physiology of waterborne and dietary silver exposure in freshwater fish

contributor:
Wood, Chris M.
Biology

subject: Biology Biology

abstract: Water quality criteria regulating silver discharge to the environment have been heavily scrutinized by both the photographic industry and the regulatory community over the last decade. In the United States, there is now a general consensus that the present regulatory framework, which is based on work done in the 1970's, fails to appropriately assess the impact of silver in the environment. Nonetheless, other countries have begun developing water quality criteria for silver which are in many cases based on this same old toxicological information. The present thesis addresses the need for new information, and specifically characterizes the toxicological, physiological and biochemical responses of freshwater fish to waterborne and dietary exposures of silver. This thesis provides concrete evidence that acute waterborne toxicity in juvenile rainbow trout is produced by the free Ag+ ion, yielding 4 to 7-day LC50 values ranging from 3.1 to 5.5 μg/L Ag+ . In comparison, LC50 values varied by as much as 30-fold during toxicity tests in which complexing agents such as chloride and dissolved organic carbon were manipulated. Using these data, together with other recently published results from physiologically-based studies, a new acute toxicity model has been developed within a Biotic Ligand Modeling (BLM) framework where the geochemistry of the receiving water is taken into account. This new acute toxicity model is unique in that it relates toxicity to a prediction of the binding of Ag+ to toxic sites on the gill, rather than to a prediction of total gill silver load. This distinction is important because the total bioaccumulated silver load appears to be unrelated to the acute toxic response. Silver accumulated in the liver is shown to bind to metallothionein within the cell, possibly explaining why silver can accumulate to high levels in the liver during waterborne silver exposure with no apparent toxicity to the fish. Chronic exposure to low levels of silver results in a significant disturbance to plasma Na+ and Cl- at levels from 0.1 to 0.5 μg/L total silver. The ionoregulatory disturbance is mild in comparison to acute waterborne exposure to LC50 levels of silver, and requires longer to be fully manifested. Interestingly, fish show physiological acclimation to silver-induced perturbations in ion balance after only 7 to 16 days, and toxicological acclimation to 3.0 μg/L total silver exposure after 23 days. Acclimation appears to be associated with enhanced branchial Na+ influx and Na/K-ATPase activity (the target of Ag+ ), despite the continued presence of metal in the water. Considering the level of silver required to elicit toxicological acclimation, it is unlikely that acclimation will significantly impact the predictive capability of the acute toxicity model. Finally dietary exposures to silver sulfide up to 3,000 μg/g and a biologically incorporated silver up to 3.1 μg/g produced no physiological impairment in juvenile rainbow trout during long-term studies. Interestingly, the biologically incorporated form of silver was accumulated in the livers of fish over four orders of magnitude better than dietary silver sulfide. The fact that the bioavailability of dietary silver is influenced by speciation suggests that a Biotic Ligand Modeling approach may be plausible for dietary silver exposure.

abstract: Doctor of Philosophy (PhD)


title: Electromagnetic Properties of 2-dimensional dx²y² Symmetry Superconductors

contributor:
Carbotte, J.P.
Physics

subject: Physics Physics

abstract:
A 2-dimensional dx²y² symmetry superconductor is studied. The model used is a two dimensional Hubbard model with tight binding electrons in the plane with both nearest neighbor and next nearest neighbor hopping. The superconductivity is stabilized by anti-ferromagnetic spin fluctuations and is described by the Eliashberg theory.

With this model a general set of Eliashberg equations are derived which are valid for any electronic band structure and also the details of the electron-boson interaction can be included, and impurity scattering of arbitrary strength. This is possible because no model for the electronic density of states has been taken and thus all of the details of the density of states including the van Hove singularity can be accounted for fully. This leads to a non-trivial difference not previously seen between impurity scattering in the Born limit and that of impurity scattering in the unitary limit. The Eliashberg equations are solved numerically, and the effect of band structure and impurity scattering on the critical temperature is examined.

General expressions for the London penetration depth and the optical conductivity are derived. These are calculated for different impurity concentrations and scattering strengths, and band structures. It is found that the inverse square of the low temperature penetration depth is linear in temperature. This behavior can be changed to quadratic by adding small concentrations of impurity scattering in the unitary limit or by large concentrations of scattering in the Born limit. The conductivity of the normal state as well as that in the superconducting state also have a large dependence on the type of scattering included. The optical conductivity in the superconducting state shows no evidence of a gap in the spectrum in contrast to conventional superconductors. These results are compared with experimental observations on impurity doped high-Tc superconductors where similar behavior is observed.

abstract: Doctor of Philosophy (PhD)


title: An Analysis of the Effect of Locational Factors and Accessibility on Discretionary Trip Generation Using an Ordered Response Model

contributor:
Hall, Fred L.
Geography

subject: Geography Geography

abstract:
The research reported in this thesis constitutes an attempt to address some of the methodological problems in the existing Urban Transportation Modelling System for trip generation analysis, and to provide new empirical evidence on the effect of locational factors and accessibility on discretionary trip making using data from the Greater Toronto Area (GTA).

Three separate analyses were performed using an ordered response model, a type of discrete choice model that exploits the ordering of information in the dependent variable in situations where there are more than two responses. One type of analysis examined the effects of geographic location of households on weekday, home-based shopping trips. Five zones (planning districts) within the GTA were chosen to reflect different types of location. The statistical results of this analysis show that, after controlling for some household's socioeconomic characteristics, its location within the metropolitan area has some effect on its weekday, home-based shopping trip generation. In particular, households located in the older urban area are likely to make fewer trips than those living in the suburbs.

The second type of analysis focused on Metropolitan Toronto, which constitutes a greater part of the GTA. In this analysis, gravity measures of accessibility were calculated and used along with the socio-economic characteristics to estimate the ordered response model. The results of this analysis in terms of asymptotic t-statistics suggest that accessibility is not a significant input into trip generation decisions of households in the metropolitan area.

The third analysis has two objectives. The first objective is to investigate the direct spatial transfer of an ordered response model. Investigating the impact of a scaling updating technique on the transferred ordered response model in another spatial context is the second objective. The results of this spatial transferability analysis show that a directly transferred model (without any updating of the transferred coefficients) performs reasonably well in predicting the choice probabilities in the application (new) context. Revising the constant terms and scalars in the ordered response model using the scaling updating technique substantially improves the predictive ability of the transferred model.

Overall, two implications can be identified from these analyses. First, the ordered response model is a useful methodology for the analysis of trip generation. The trip-making decision should therefore be treated as a multiple response with a natural order, not as a continuous variable or a dichotomous response. The other implication is that while weekday, home-based shopping trip generation is sensitive to the location of the households, the gravity-based measure of accessibility was not found to be a significant factor in the trip-making decision.

abstract: Doctor of Philosophy (PhD)


title: Design and Synthesis of Harmonic Surface Acoustic Wave Delay Lines

contributor:
Campbell, C.K.
Electrical Engineering

subject:
Electrical and Electronics
Electrical and Electronics

abstract: Harmonic delay lines are necessary for building SAW oscillators in the 200 MHz - 1 GHz frequency range using conventional photolithographic techniques. The various methods of generating and filtering higher harmonic modes in Surface Acoustic Wave (SAW) delay lines are presented in this thesis. A new design called the "stepped-finger" design, for SAW transducers was also developed in this thesis. A stepped-finger harmonic delay line was built, tested and compared with the only other presently existing harmonic delay line structure, the 3- and 4-finger delay line. The experimental results obtained indicated that the stepped-finger delay line was the more efficient of the two.

abstract: Master of Engineering (ME)


title: Three essays in health economics: 1. An equilibrium model of waiting lists for medical care. 2. An evaluation of alternative econometric specifications for estimating a tobacco budget share equation. 3. The determinants of expenditures on tobacco in Canada

contributor:
Feeny, David
Osborne, Martin
Hurley, Jeremiah
Economics / Economic Policy

subject: Economics Economics

abstract: This thesis consists of three essays on health economics. Chapter 1 is an introduction. Chapter 2 studies waiting lists for medical care, and Chapters 3 and 4 study the demand for tobacco products. The main contribution of Chapter 2 is a game-theoretic model of waiting times for medical care that provides new insights into how health care waiting times and the number of cases treated may be related. The model demonstrates that charging patients for medical care may not result in decreased waiting times. One policy implication of the model is the potential gains from the sharing of information and co-ordination among health-care providers. Chapters 3 and 4 are on the demand for tobacco products. Estimating the demand for tobacco involves choosing one or more econometric specifications or functional forms. Different econometric specifications can result in conflicting results, raising questions about how to interpret results. A primary objective of Chapter 3 is to identify the similarities and differences between three econometric specifications that have often been applied to tobacco data. A behavioural model is a useful starting point for making these comparisons. In this chapter I compare the results arrived at by applying different specifications to one data set. This data set reports individual's expenditure on tobacco. Chapter 4 examines a data set that reports household expenditure on tobacco. A number of economics papers examine tobacco data from the United States, the United Kingdom and Spain. Chapter 4 examines tobacco data from Canada. One finding indicates that households that do not own their home and consist of one or more unemployed individuals tend to purchase a relatively high amount of tobacco. This information may be of interest to people involved in tobacco policy.

abstract: Doctor of Philosophy (PhD)


title: Investigation of Endotoxin-induced Cytokine Expression in the Airways in Vitro and in Vivo

subject:
Medical Sciences
Medical Sciences

abstract:
Lipopolysaccharide (LPS), a component of the outer membrane of gramnegative bacteria, is a potent inflammatory stimulus responsible for a number of clinically critical airway conditions including gram-negative pneumonia, gram-negative septic lung injury and septic adult respiratory distress syndrome (ARDS). These conditions are all characterized by activation of alveolar monocytes/macrophages and massive infiltration of polymorphonuclear leukocytes (PMNs). While it is generally agreed that alveolar macrophages have a central role in the initiation of neutrophil accumulation and that the contents released from PMNs play a major part in causing tissue injury, the molecular mechanisms underlying these processes remain incompletely understood. Recently, some cytokines (polypeptide hormones) such as interleukin-1 (IL-1), tumor necrosis factor α (TNFα), interleukin-8 (IL-8) and interleukin-6 (IL-6), have been implicated in these processes, yet the expression of these cytokines by airway cells in response to LPS still remains to be fully elucidated. Thus, both in vitro and in vivo studies were undertaken to investigate the effect of LPS on cytokine gene expression and protein production by airway cells and tissues.

To investigate the regulation of cytokine expression in alveolar macrophages by LPS and extracellular matrix (ECM) components, LPS stimulated rat alveolar macrophages were maintained on different substrates: plastic, collagen and airways fibroblast-derived ECM (fECM). It was found that adherence to plastic induced IL-1β expression and that LPS further enhanced this expression in a time-dependent manner. In contrast, significant expression of IL-6 mRNA was observed only in LPS-stimulated alveolar macrophages. Adherence to collagen or fECM evoked a stronger IL-1β mRNA expression as compared to adherence to plastic. Only cells cultured on fEeM, however, retained maximal responsiveness to LPS stimulation over a period of five days in culture.

To determine whether LPS can directly act on airway-derived fibroblasts, nasal, bronchial and lung fibroblasts were exposed to LPS and expression of several cytokines including granulocyte/macrophage colony-stimulating factor (GM-CSF), IL-8 and IL-6 was assessed. While fibroblasts of all three anatomic sites produced significantly increased amounts of cytokines in response to IL-1, only upper airway-derived nasal fibroblasts could synthesize significant quantities of cytokines upon LPS stimulation.

Furthermore, the interaction of airways structural epithelial cells and fibroblasts with monocytes/macrophages was examined. Human peripheral blood monocytes were cultured with either nasal epithelial cell- or fibroblast-derived conditioned medium, and survival, proliferation and differentiation of monocytes then analyzed. Both macrophage colony-stimulating factor (M-CSF) and particularly, GM-CSF released by airway structural cells were found to dramatically promote survival and differentiation, but not proliferation, of monocytes.

To investigate the temporal sequence of cytokine induction upon LPS exposure in vivo, a rat model of acute lung inflammation was established. Kinetics and cellular origin of cytokines were examined. LPS markedly evoked an early expression of TNFα and macrophage inflammatory protein-2 (MIP-2; the rodent functional equivalent of human IL-8), followed by IL-1β and IL-6 but not RANTES (a T cell/monocyte chemotactic cytokine) or transforming growth factor β₁ (TGFB₁) expression. Alveolar macrophages represented the most significant source of cytokines shortly after LPS challenge. At later times, the infiltrating PMNs were the most significant source of cytokines in the lung.

In conclusion, these data suggest that (a) the alveolar macrophage can respond directly to LPS stimulation by elaborating and releasing cytokines; (b) this cytokine response can be modulated by the extracellular environment in which alveolar macrophages reside; (c) only the fibroblast population in the upper airway, in close proximity to the external environment, is capable of responding to LPS exposure by cytokine release. This particular fibroblast population may be thus directly involved in the initiation of acute airways inflammation; (d) monocytes/macrophages and airway structural cells communicate with each other. This interaction is accomplished in part through cytokines released from the structural cells; and (e) LPS evokes a sequential and specific cytokine response in the airways in vivo. TNFa and MIP-2 appear to play a major early role in eliciting the neutrophilic response. Consistent with in vitro findings, alveolar macrophages serve as a significant source of cytokines in vivo prior to recruitment of PMNs. Thereafter, PMNs serve as the other significant source of cytokines in vivo, suggesting that these cells likely contribute to the amplification of the response to LPS in an autocrine and paracrine fashion.

abstract: Doctor of Philosophy (PhD)


title: Inner-shell electron energy loss spectroscopy and generalized oscillator strengths at high momentum transfer

contributor:
Hitchcock, Adam P.
Chemical Physics

abstract: Detailed information about the energies of the electronically excited and ionized states of atoms and molecules is of central importance to the understanding of the interaction of energetic radiation with matter. Such data permits a more complete understanding of various processes taking place in physics, chemistry or biology, with important areas of application including electron and X-ray microscopy, space physics and chemistry or any other area where energetic radiation is used. This work documents the improvements and performance of a variable scattering angle energy loss spectrometer used to investigate inner-shell electronic spectroscopy of gases and to map generalized oscillator strengths. Wide ranges of impact energy and scattering angle are used to study both electric dipole and non-dipole transitions. New spectroscopic studies include: (i) the observation of the non-dipole "B-state" in SF6 S 2 p edge at very high scattering angle (62°) and at 1550 eV impact energy, where it dominates the spectrum; (ii) the first experimental observation of the C 1s [arrow right] σg * transition in CO2 . Generalized Oscillator Strength (GOS) profiles were mapped systematically for a collection of molecules: in SF6 , the GOS for S 2p and S 2s were extended up to very high momentum transfer, while the GOS for F 1s was mapped here for the first time. GOS curves were also obtained for all edges in CO 2 , COS and CS2 , some of them revealing their shapes for the first time. Where available, the results were compared to theoretical calculations. This work greatly extends previous reported studies of GOS for inner-shell excitation.

abstract: Doctor of Philosophy (PhD)


title: Formulation and Applications of Consistent Shell and Beam Elements

contributor:
Mirza, F. A.
Civil Engineering

subject:
Civil Engineering
Civil Engineering

abstract:
A new shell element for the analysis of thin and thick plate and shell structures has been formulated along with the compatible beam element. The new elements are referred to as the consistent shell element and the consistent beam element. By combining the consistent shell element and the consistent beam element a finite element model for the analysis of reinforced concrete structures has been formulated. The scope of the study is broadened further through the modification of the new elements to allow for the analysis of laminated fiber-reinforced composite beams and shells.

Many of the currently available beam and shell elements exhibit spurious variations of the transverse shear stress(es). To obtain improved responses when thin beams or shells are analysed the reduced integration technique has typically been employed. This approach is not acceptable since the reduced integration technique cannot be applied with complete confidence. In the present study it is found that the unsatisfactory behaviour of these elements is due to an inconsistency in their formulation. In the formulation of the new elements a consistent formulation has been ensured. The new elements behave very well in the analysis of both thin and thick beams and shells and contain no spurious zero energy modes. In addition, they provide a quadratic variation of the transverse shear stress(es), and a cubic variation of the displacement(s) through their thicknesses. Therefore, the shear correction factor k, which is usually required to correct for the assumption of constant transverse shear strain through the thickness is not required. Both elements include material non-linearity. Special attention has been given to the efficient implementation of the consistent shell element by employing a sub-matrix formulation in conjunction with a modified frontal solution algorithm. The numerical results show the new elements to be highly accurate and computationally efficient.

The reinforced concrete finite element model employs a rational elasto-plastic constitutive relationship for concrete, discrete bar elements for modelling of reinforcement, joint elements for bond slip between concrete and reinforcement, beam elements for supporting girders and shear connector elements along the concrete/girder interface. The numerical results show that the model accurately predicts the behaviour of reinforced concrete slabs, including punching shear failure under point loads. The constitutive model employed has been found to be reasonably objective with respect to refinement of the finite element mesh.

The consistent laminated beam element and the consistent laminated shell element, have been formulated for the analysis of laminated fiber-reinforced composites. Special attention has been given to the approximation of stresses through the thickness of the laminate because of their importance in predicting delamination failures. This has been achieved by allowing the transverse shear strain(s) to be discontinuous at the interface of two layers while still maintaining continuity of the global displacements across the interface. The numerical results show that the elements provide very accurate predictions of stresses through the thickness of both thin and thick laminates.

abstract: Doctor of Philosophy (PhD)