title: On the Capacity Analysis of A DS/FH CDMA System for the PCS

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

abstract:
The main objective of this thesis is to design a PCS system with high capacity. We find that the hybrid DS/FH CDMA method is a promising technology to achieve this goal. Designing such a system and analyzing its capacity are the major contributions of this thesis.

CDMA technology potentially offers higher capacity than the other multiple access methods. However, there are serious problems in implementing DS-CDMA to PCS. These are the long acquisition and "near-far" problem. Both these two problems reduce the system performance, and require complicated hardware solutions.

The idea of applying hybrid DS/FH CDMA technique to PCS system is initiated for trying to solve the long acquisition problem. We also find that by taking advantage of FH, we can solve the "near-far" problem without increasing system complexity.

The capacity of CDMA systems is limited by mutual interference of users, and the interference level is determined by two major factors: the precision of synchronization and the code property. The most important property of the codes is the cross-correlation. The lower the cross correlation among the codes, the higher the capacity will be. Based on this criterion we explore the performance of different codes. In addition, we proposed to use codes generated from the same maximum-length sequence with a unique phase, which offer the lowest cross correlation in the family of non-orthogonal codes.

Another detriment to the performance of the system is the imperfection of synchronization due to random access and propagation delays. We propose to implement time slots and deterministic coordinated hopping patterns. Such a measure not only helps to save acquisition time and power control, but also increases the capacity dramatically, by way of establishing synchronous access and avoiding frequency collisions. We show that quasi-synchronous access can be achieved for uplink and completely synchronous access can be achieved for downlink. Our theoretical analysis as well as simulations showed that, by ignoring the adjacent cell interference, system capacity in a single cell can approach its hard limit defined as the ratio of total bandwidth to the message bandwidth for a reasonable bit error rate.

A major concern in applying CDMA to PCS is the interference from adjacent cells, since the whole spectrum is reused in all the adjacent cells. Mathematical models for calculating such interference power have been developed, in terms of propagation characteristics, code properties, etc. The results reveal significant impairment on the capacity due to this interference. Voice activity cycle plays an important role now and can triple the capacity in one cell to approach the hard limit N. Without it, the capacity can only be about N/3 in one cell, for an acceptable BER (10ˉ³) and reasonable Eb/N₀. The capacity of this hybrid system has the potential of being much larger than that of TDMA system.

abstract: Doctor of Philosophy (PhD)


title: Integrated Numerical Modeling Techniques for Nominal and Statistical Circuit Design

contributor:
Biernacki, Radek M.
Electrical and Computer Engineering

subject:
Electrical and Computer Engineering
Electrical and Computer Engineering

abstract:
This thesis contributes to computer oriented techniques for nominal and statistical design of analog circuits. Innovative software concepts aiming at shortening the design time are described. The problem of interfacing circuit CAD tools for design automation is addressed.

The concept of response modeling is reviewed. Benefits and limitations of utilizing response modeling in nominal and statistical design are discussed. A multilevel approach to response modeling offering additional CPU time savings is introduced. Challenges associated with employing grid- based simulators with discrete parameters in the design process are addressed.

A highly efficient quadratic interpolation technique is reviewed, extended and used for response modeling. Dedicated data base techniques and an effective parallel processing scheme are developed to complement the quadratic interpolation and further increase the CPU time savings.

Flexible circuit optimization where a powerful optimization system can interact with various external simulators is addressed. An interface capable of integrating such an optimization system with external and independent simulators is developed. Approaches to automating the process of preparing the external simulator input and capturing its output are described.

The novel Space Mapping approach to optimization with CPU intensive simulators is reviewed.

The theoretical and software developments are implemented and tested on several advanced and industrially relevant circuit problems. Results of designs utilizing circuit theory-based and electromagnetic simulators are reported.

abstract: Doctor of Philosophy (PhD)


title: Non-Dipole and Dipole Core Electronic Excitation

contributor:
Hitchcock, Adam P.
Chemistry

subject: Chemistry Chemistry

abstract:
In contrast to photoabsorption techniques, which are subject to electric dipole selection rules, electron energy loss spectroscopy (EELS) can provide a more complete investigation of atomic and molecular electronic structure. This is due to the added capability of accessing dipole and/or spin forbidden electronic transitions under conditions of significant momentum transfer.

This work documents the design, construction and performance of a new, high resolution, variable scattering angle, variable impact energy electron spectrometer (McVAHRES) which has been used to investigate electronic transitions in gas phase atoms and molecules under both dipole and non-dipole conditions. The home-built instrument features a complex electron optics system and a sophisticated, computer-interfaced electronics system which allows a high degree of flexibility with regards to control and acquisition. This permits a wide range of experimental conditions.

New spectroscopic studies include the observation of spin-forbidden, C is core excited triplet states in C₂H₄, C₂H₂, and C₆H₆. The momentum transfer dependence of the (C 1sˉ¹, π*) ³π state of CO was also investigated. These results are compared to the results of theoretical calculations. Generalised Oscillator Strengths (GOS) as a function of momentum transfer were derived for the S 2p edge of SF6. This work greatly expands previous results reported in the literature. Finally, an interesting feature was observed in the S 2p spectrum of SF₆, which displays quadrupolar momentum transfer behaviour.

abstract: Doctor of Philosophy (PhD)


title: Structural Studies of the Killarney Igneous Complex, Ontario and Their Tectonic Implications

contributor:
Clifford, Paul M.
Geology

subject: Geology Geology

abstract:
The Killarney Igneous Complex (KIC), one of a suite of plutons known as the Killarney Magmatic Belt along the Grenville Front Tectonic Zone (GFTZ), consists of granite, porphyry and volcanic rocks, forming a wedge between Huronian metasediments of the Southern Province and the Grenville Province gneisses.

Structural analysis of micro- and meso-scopic structural features of the KIC suggests that a set of subparallel faults observed in the research area are thrusting faults with substantial dextral horizontal movement. Various kinematic indicators are examined and proved very useful in determining the sense of shear accommodated by the faults. Palaeopiezometry indicates that the differential stress related to the thrusting ranged from 85 MPa to 146 MPa, with average of 100 MPa and standard deviation of 15 MPa, similar to the results obtained from other major thrusting zones. Fault-slip analysis reveals that the maximum compressive stress responsible for the thrusting came from the WNW direction, supporting the tectonic model that these faults were imposed by the indentation of the Superior craton.

Two fracture variations, namely, kinks and wedges, are found common in the KIC and are studied theoretically and practically. The study provides valuable insight into the palaeostress field and the regional structural development in the research area. Kink angles are found to be a reliable kinematic indicator, and are determined by the ratio of the effective shear stress and the effective normal stress acting on their parent fractures. Wedge angles are found to be the prime factor controlling the fracture patterns developed within wedges; the formation of wedges was associated with the development of main faults.

These structural studies are integrated with previous work of geochronology into a tectonic model for the geological history of the KIC and the surrounding area. During the period of 1.75-1.65 Ga, the KIC was emplaced in a transtension zone due to the southeasterly indentation of the Superior craton or the northwesterly encroachment of the block of Grenville Province. After its emplacement, the KIC underwent two major compressional events: the first one imposed a regional foliation and lineation in the porphyry-volcaniclastic assemblages, at about 1.62 Ga; the second event, due to a renewed southeasterly indentation of the Superior craton or northwesterly encroachment of the Grenville Province, imposed the thrusting faults in the area, and effectively produced a transtension zone between the KIC and the Grenville Province, so providing the space and the thermal environment for the emplacement of the Bell Lake Granite (ca. 1.47 Ga).

abstract: Doctor of Philosophy (PhD)


title: Multiaxial Creep Testing of Rock and Concrete

contributor:
Emery, John J.
Civil Engineering

subject:
Civil Engineering
Civil Engineering

abstract: The finite element method of simulating tunnel excavations in squeezing ground requires experimental data on multiaxial creep relationships and related characteristics of rock and concrete as input. A servo-controlled test frame, for applying multiaxial stress states to cubical specimens through three independent actuators, was developed. This test system allows the simulation of typical stress levels and stress paths involved during rock excavation, with continuous monitoring of loads and displacements through a data acquisition system. The overall equipment development required considerable design and assembly effort. A testing programme for concrete specimens was completed to evaluate the equipment. Finally, conclusion and recommendations were made which provide the necessary information and guidance for future testing to develop multiaxial creep relationships for rocks known to have significant time-dependent behaviour.

abstract: Master of Engineering (ME)


title: Dynamic Modelling of Flexible Multibody Systems Subjected to Frictional Impact

contributor:
Dokainish, M.A.
Mechanical Engineering

subject:
Mechanical Engineering
Mechanical Engineering

abstract:
A corotational finite element formulation for flexible multibody systems which are subjected to frictional impact is developed in this thesis. The formulation can predict the motion of the system, the contact forces, the velocities, the accelerations, the duration of impact and the associated deformations.

First, a corotational finite element formulation is developed for the dynamic analysis of flexible multibody systems without impact. A numerical algorithm is developed along the lines of the incremental-iterative method of the Newmark direct integration and Newton-Raphson methods.

Frictional impact is then included in the formulation. The prediction of contact establishment and separation is achieved using an event predictor. Point impact is assumed and Coulomb's friction law is used to model the friction forces.

Two multibody-oriented approaches are used to model the frictional impact. The first approach is based on a modified momentum balance model. An energy-based method is developed to resolve the problem of energy mismatch which arises with the use of Newton's impact law or Poisson's hypothesis. The concept of the coefficient of restitution is used and a new technique is developed to calculate the contact forces in some special cases. In general, it is assumed that multiple impulses occur during the contact period. An automatic time stepping algorithm is developed for numerical solutions.

The second approach is based on the Lagrange multiplier method. The model exactly satisfies the geometric compatibility conditions during contact. It also allows the direct evaluation of the contact forces. Both sliding and sticking modes are considered. The proposed scheme overcomes the problem of high dimensionality in the traditional Lagrange multiplier models in structural dynamics.

The applicability and accuracy of the formulation and the numerical technique are demonstrated. Simulation of various mechanical systems, which are subjected to impact loads, are presented.

abstract: Doctor of Philosophy (PhD)


title: Non-Linear Dynamic Extension of Consistent Shell Element and Analyses of Liquid-Filled Conical Tanks

contributor:
Korol, R.M.
Mirza, F.A.
Civil Engineering

subject:
Civil Engineering
Civil Engineering

abstract:
Conical steel shells are fairly widely used as elevated water tanks. However, the current code of practise in North America for the design of such reservoir structures provides an obsolete method for ascertaining their adequacy to resist hydrostatic loadings. Moreover, there are no provisions available for handling liquid-filled conical tanks subjected to seismic forces. The lack of appropriate design methods could not have been demonstrated more vividly when in December of 1990, an elevated conical water tower failed by buckling when being filled for the first time. The steel vessel, located in Fredericton, New Brunswick, is claimed to have "exploded" by eyewitnesses.

The work of this thesis, then, was motivated by this failure. It involves non-linear stability analysis of liquid-filled conical steel vessels possessing geometric imperfections and residual stresses, and which can be subjected to hydrostatic and seismic loading. To achieve this, a finite element formulation is developed based on a consistent shell element which is free from spurious shear modes known to exist in the isoparametric shell elements. The consistent shell element employed also exhibits excellent performance in the analysis of plates and shells in the small displacement range. This element is extended to include both geometric and material non-linearities as well as non-linear dynamic analysis. The non-linear finite element model developed is general and can be applied to any thin or thick shell problem. Numerical testing of the non-linear model through static and dynamic analysis of different plate and shell problems indicates the continued excellent performance of the consistent shell element in the non-linear range.

Hydrostatically loaded conical steel vessels are modelled using the consistent shell element. Static stability analyses of conical shells with different geometric imperfection patterns are undertaken and the results indicate that the presence of axisymmetric imperfections leads to the lowest limit load for the structure. The sensitivity of the hydrostatically loaded conical vessels to geometric imperfections and residual stresses is investigated by considering three cases: (i) analysis of perfect vessels, (ii) same as case (i) but with axisymmetric geometric imperfections of the order of the thickness of the shell, (iii) same as case (ii) but with the addition of residual stresses due to welding. The results from these analyses indicate that the liquid-filled conical shells are significantly sensitive to geometric imperfections, and that yielding precedes elastic buckling for tanks having practical dimensions.

The non-linear dynamic (stability) analysis of elevated liquid-filled conical vessels subjected to both horizontal and vertical accelerations, but free from rocking motion, is then considered. The boundary integral method is used to formulate the fluid added-mass matrix resulting from the impulsive component of the hydrodynamic pressure. This is added to the mass matrix of the shell structure to perform free vibration as well as nonlinear time history analyses for elevated liquid-filled conical tanks treated as either perfect or axisymmetrically imperfect. Tanks with different dimensions and imperfection levels are subjected to an appropriately scaled real input ground motion. Some of these elevated structures exhibit inelastic behaviour and generally develop a localized buckle near the bottom of the vessel which leads to the overall instability of the structure. In general, time history analyses indicate that liquid-filled conical tanks, often possessing apparently adequate safety factors under hydrostatic loading, may not be safe under seismic loading. Therefore, a proper modelling procedure along with time dependent analysis must be followed in order to design such tanks safely. The finite element model developed in this thesis is a means provided for such a purpose.

abstract: Doctor of Philosophy (PhD)


title: Transition Metal Nitride Surfaces and Electrons: An AES/LEED Study of the Formation of Transition Metal Nitride Surfaces and the Effect of Electron Stimulation

contributor:
Dawson, P.T.
Chemistry

subject: Chemistry Chemistry

abstract:
This thesis reports a comprehensive study of transition metal nitride surfaces and the effects of electron beam stimulation on the adsorption processes. Since the nitrides of transition metals in the fourth to sixth group of the periodic table have important industrial applications as coating materials and heterogeneous catalysts, the understanding of the surface nitriding processes has tremendous technological importance.

AES studies have been carried out on the N-Zr system over a wide energy range which has led to the identification of new Auger cross transition features induced by nitriding and to an understanding of the intensity variation and energy shift of Auger features during nitriding. Consequently, a quantitative surface analysis method has been established for this system.

The effect of electron beam stimulation on the processes of ammonia adsorption and nitride film growth has been investigated on polycrystalline Ti, Cr, Zr, W and three single crystal tungsten surfaces. This study demonstrates methods for performing experiments properly when surface science tools utilising electron probes are used, and provides a potential application for the development of new techniques for preparing transition metal nitride films.

Titanium and tungsten represent extremes in the stability of their nitrides. Extensive studies of the interaction of ammonia with these metals are reported in this thesis.

The adsorption of N₂ and NH₃ gases with and without electron beam stimulation has been studied on titanium surfaces. This has led to an understanding of many surface processes including the adsorption of gas molecules, the diffusion of nitrogen atoms into the bulk and the initial stage of nitride film growth. It has been found that only with electron stimulation does the adsorption and diffusion behaviour of N₂ gas mimic that of ground state NH₃ gas.

AES and LEED studies on the interaction of NH₃ with tungsten single crystal surfaces have been performed including the stimulation effect of electrons in ammonia adsorption. Nitrogen desorption and diffusion have been observed during annealing and surface structural changes have been monitored. A remarkable surface reconstruction involving nitrogen atom transfer from the outermost layer to the underlayer has been revealed on the W(100) surface. These results lead to new insights into the complex surface chemistry of the NH₃-W(100) system.

abstract: Doctor of Philosophy (PhD)


title: Permeability Studies of Wood Fibre Beds

contributor:
Pelton, R.H.
Baird, Malcolm H.I.
Chemical Engineering

subject:
Chemical Engineering
Chemical Engineering

abstract:
The effect of polystyrene beads and nylon fibres on the permeability of bleached kraft pulp fibre beds was studied experimentally. Three types of experiments: 1) constant head filtration, 2) elastic permeation, and 3) fixed bed permeation were carried out. Four types of fibre beds were used: 1) pulp fibres only, 2) pulp fibres and plastic beads, 3) pulp fibres and nylon fibres, and 4) pulp fibres, nylon fibres and plastic beads. The beads used were 80 μm in diameter while the diameter and the length of the nylon fibre were 45 μm and 1.89 mm respectively. The beads were used as a model for dispersed air bubbles in pulp suspensions, while the nylon fibres were chosen because their specific surface area and specific swollen volume were close to those of the beads.

In a filtration experiment, a fibre bed was formed from the corresponding suspension while pressure drop across the bed and cumulative filtrate weight were recorded: Specific filtration resistance values for the suspensions were calculated from the filtrate weight data. It was observed that specific filtration resistance increased with bead content in the slurry while filtration resistance decreased with an increase in the content of nylon fibres in the suspension. A mathematical model based on permeation equations was derived to simulate the filtration process.

In a permeation experiment, the fibre bed formed in a filtration experiment was subjected to a complete recovery-compression cycle starting with the maximum pressure drop. Flowrate of water through the bed and the thickness of the bed were measured as a function of the pressure drop. Fibre beds of the four different compositions all displayed hysteresis in both the flowrate and bed thickness data. Bed thickness data were correlated by regression analysis and under flow induced compression the thicknesses were found to be linear or nearly linear functions of the pressure drop acting across the bed. The presence of plastic beads did not affect the structure and thickness of the beds, suggesting that the plastic beads were able to fit into the pores of the pulp bed without disrupting the structure. By contrast, nylon fibres increased both the permeability and the thickness of the bed because of the formation of a more open network structure. The mathematical model proposed by Jonsson and Jonsson was used to predict compression behaviour; however, the concave form of plot of thickness versus pressure drop during recovery was not predicted by any of the current bed compressibility models.

Permeability of the compressed bed formed in the filtration experiment was measured in a fixed bed permeation experiment. Permeability of the bed was used to calculate the specific external surface area and specific swollen volume of the bed materials using the Kozeny-Carman equation. It was found that for both the pulp/bead system and the pulp/nylon fibre system, the specific surface area and specific swollen volume of the bed were linear functions of the content of polystyrene beads or nylon fibres. The specific surface area and specific swollen volume of beds that contained pulp fibres, nylon fibres and plastic beads were predicted, within 7%, by the linear supposition of the specific surface area and specific swollen volume of the bed constituents. This analysis is important because it permits estimation of the effect of air bubbles on the permeability of pulp pads in various processes in the pulp and paper industry.

abstract: Doctor of Philosophy (PhD)


title: Beyond the Rule of Law: Aspects of the Defence of Realm Acts and Regulations, 1914-1918

contributor:
Rempel, R.A.
History

subject: History History

abstract: No piece of war legislation enacted in Great Britain during the First World War had such diverse and far-reaching effects as the Defence of the Realm Act, one of the first emergency steps taken by Asquith's Liberal Government in August 1914. The acronym DORA, by which contemporaries soon began referring to this general emergency statute, or 'enabling' law, is a familiar one to anybody with the most cursory knowledge of the British Home Front between 1914 and 1918. Both the act and its supplementary code of regulations are often mentioned, but seldom explained, in historical accounts of Britain and the First World War. There is in this substantial body of work, however, no detailed treatment of DORA; its legal and constitutional aspects have been especially neglected. For the past thirty years the historiography of Home Front in Britain during the First World War has been dominated by study of mass participation in the war effort and of the long-term social and political consequences of this mobilisation for 'total' war. This influential 'war and social change' school of historical thought has been contested by historians who view modem industrialised warfare as the occasion for, rather than agent of, change and by those who question whether 'total' war has materially affected class or gender inequalities at all. Yet all three shades of historiographical opinion have to a large extent been debating an agenda set by issues of social structure, gender, social provision, prices and incomes, and public health. Without challenging directly this broad historiographical tendency, this thesis does imply that, if the transformative effects of war, or otherwise, are to be properly assessed, then issues of the law and constitution deserve rather more attention than they have received hitherto. Although the thesis attempts to convey the range of uses to which DORA was put by successive wartime administrations, it concentrates on a number of contentious civil liberties issues. After the examination in chapter one of DORA's origins, a series of related case studies deal with the following subjects: wartime challenges to customary judicial procedures; the impact of DORA on organised opposition to British war policy; and, finally, the assortment of coercive measures that were implemented to address the problematical venereal disease question. The epilogue surveys the role of DORA in the aftermath of war. The unitary theme of these chapters is the contribution of DORA to the erosion of executive accountability and the growth of state power in wartime Britain. To place so much weight upon questions of civil liberties is perhaps to risk regressing to the old, whig-liberal view of the wartime state as a portent of totalitarianism and of war in general as an unfortunate interruption in the orderly march of liberty and progress. However, the expansion of the British state has become a focus of much renewed critical scrutiny of late, and the thesis is certainly reflective of this historiographical reorientation. This thesis is based to a large extent on the records of the Home Office and the War Office-the two departments most intimately involved with the special powers that have been selected for analysis. It is principally concerned with the evolution and administration of some exceptional war measures. Yet considerable attention is also paid to the critical response which these governmental initiatives elicited and to the overall civil libertarian and constitutional case against DORA. The distinctive contribution of this work is its clarification of some assumptions which both contemporaries and historians have made about this controversial body of war legislation. The ensuing discussion, therefore, closes a sizeable gap in the historical literature. In addition, this study of DORA should raise some broader questions about the changing character of government in twentieth-century Britain in particular, and about emergency executive discretion in democratic political systems generally.

abstract: Doctor of Philosophy (PhD)


title: Pressures and Constraints: The Ontario "Spills" Bills

contributor:
Walters, V.
Sociology

subject: Sociology Sociology

abstract: This dissertation uses a case study of environmental legislation, the Ontario "Spills" Bill, to explore why sometimes the capitalist state acts against the capitalist class and the role of social forces in this process. In so doing it employs a Gramscian analysis to examine the various strategies of the Bill's supporters and opponents, and the government's response. It utilizes an interpretive historical methodology, with archival material and interviews with key informants as its data sources. The substantive goal of the dissertation is to improve our understanding of the problems inherent in the creation of effective pollution legislation. The study establishes that in this case fluctuations in the balance of power affected the government's position; and that these were influenced by structural constraints, power resources, political change, alliances, prevailing ideologies, environmental events and the international insurance market. In addition, it notes that underlying this struggle was another conflict over the institution of a new legal regime. The perception that there is a lack of differentiation between the types and uses of the property owned by polluters is identified as aiding the maintenance of the status quo. Health is observed to act as a surrogate for environmental issues in pressuring for change, but to provide only a fragile foundation for environmental change. Overall, the project illustrates the structural constraints that limit the actions of governments and restrict the influence of capitalists. Additionally, it demonstrates the role of agency in encouraging change, and the obstacles that political will can overcome to achieve any change.

abstract: Doctor of Philosophy (PhD)


title: Study of Radiocarbon Detection By laser spectroscopy

contributor:
Reid, J.
Physics

subject: Physics Physics

abstract:
This thesis examines the feasibility of using infrared spectroscopy to carry out radiocarbon dating. Conventional radiocarbon dating techniques are limited in sensitivity by the very small fraction of C¹⁴ atoms which disintegrate during the counting period. Our proposed infrared technique does not suffer from this limitation, but we must overcome the problem of interfering infrared spectra caused by stable isotopes, and develop methods for detecting extremely small infrared absorption coefficients.

The apparatus employed consists of a tunable diode laser and a multipass optical cell. Radiocarbon is detected in the form of C¹⁴O₂, and it is shown that interference-free detection can be attained provided the gas sample is cooled to dry ice temperature. To achieve sufficient sensitivity we have developed a second harmonic detection scheme. As part of out optimisation procedure, the experimental and theoretical second harmonic lineshapes were compared over a wide range of experimental conditions. Good agreement was found in all cases.

With the present apparatus, the minimum detectable infrared absorption coefficient was ~ 1x10ˉ⁷ mˉ¹. This compares with a sensitivity of ~ 1x10ˉ⁹ mˉ¹ which is required for practical radiocarbon dating. The noise mechanisms which limit the present sensitivity were investigated in some detail, and results obtained at short time constants in small optical cells are extrapolated to long optical cells and measurement times of several hours. Based on these extrapolations, radiocarbon dating by infrared spectroscopy appears feasible, and will require much smaller carbon samples than is required by conventional disintegration counting techniques.

abstract: Master of Science (MS)


title: The Nature of the Relationship Between William Langland's "Piers Plowman" and the Wycliffite Sect

contributor:
Braswell, Laurel
English

subject:
English Language and Literature
English Language and Literature

abstract:
"Piers Plowman" and the Wycliffite sect both developed out of the spiritual upheaval sweeping fourteenth-century England. They dispaly many similar interests, such as concerns with socio-economic problems, the responsibilities and choices of the individual, and the uses and abuses of wealth and language. Although such similarities exist, analysis of the treatment of these concerns shows that Langland and the Wycliffites do not share a common point of view, even when the concern is of a very general nature. The one exception is the subject of kingship, in which the treatment of Langland's ideals come close to concepts developed by Wyclif.

There is tangible evidence that the Lollards were influenced by "Piers Plowman" and that they interpreted the text as sympathetic to their sect. On the other hand, there is less evidence that Langland was aware of Lollardy's existence. Certain changes from the B-text to the C-text, especially the character of Rechelesnesse, suggest that Langland did know of Lollardy; but, in spite of an early critical view that put Langland within the Wycliffite dissenting tradition, Langland's attitude toward Lollardy is never readily discernible. Nevertheless, analysis of Langlands' attitude toward things "Lollard" in character shows that his reaction to the Wycliffite sect would be conservative and negative. In sum, the comparison of Wycliffite material and "Piers Plowman" demonstrates the context in which Lollardy and "Piers Plowman" should be related - a common interest in controversy and spiritual reform, but with insurmountable differences in outlook. It also demonstrates how two groups with contemporary yet very different points of view tried to resolve the major religious, social and economic troubles of late fourteenth-century England.

abstract: Doctor of Philosophy (PhD)


title: The role of attention in the modulation of response selection: Attenuating object-specific benefits

contributor:
Milliken, B.
Psychology

subject: Psychology Psychology

abstract: Every day we encounter a variety of objects in a complex sensory environment. Some objects are familiar, whereas other objects have never been encountered before or are novel within the current context. Response to a novel object typically requires analysis of current perceptual information of the object. By contrast, retrieving a memory for a prior event is often a useful 'shortcut' to response for a familiar stimulus. However, in some situations a past response is inappropriate for a current object, even if it is similar to an object encountered previously. Consequently, past experience may be a source of interference in response selection under some conditions. In these circumstances, relying on the analysis of current perceptual information of the object may be a more useful approach to response selection. It is proposed in this thesis that attention during the current encounter with a stimulus modulates the contribution that retrieval processes and analytic perceptual processes make to response selection. The priming method is often used to examine how prior experience influences current responding. To examine the role of attention in modulating response selection, different attentional manipulations were used in a series of priming experiments. The results of a word-naming experiment showed that the appearance of response benefits and costs for repeated stimuli was contingent on the presence or absence of a distracting stimulus in the second of two priming displays. Then, a series of experiments was conducted using a modified version of the procedure employed by Kahneman, Treisman and Gibbs (1992) to compare responses to identical and non-identical repetitions of stimuli (the object-specific preview effect). An object-specific preview benefit was eliminated both when a distractor was included in the second display and when the proportion of repeated trials was reduced below chance. Further, repetition costs emerged for repeated stimuli under the same conditions in which an object-specific preview benefit was not observed. Together, the findings are highly consistent with the proposal that attentional processing during the current encounter with a stimulus influences the contribution that retrieval makes to response selection.

abstract: Doctor of Philosophy (PhD)


title: Magnetic frustration in transition metal oxides with triangular, tetrahedral and square planar magnetic sublattices

contributor:
Greedan, J.E.
Chemistry

subject: Chemistry Chemistry

abstract: The solid solution Lux Sc(1- x) MnO3 has been prepared for 0.00 ≤ x ≤ 1.00. All members crystallize in space group P 6 3cm . The triangular antiferromagnets form 120° spin structures with Néel temperatures between 91K and 130K. Below TN all samples show evidence of out of plane spin canting. With the exception of LuMnO3 for all compositions an in-plane spin-reorientation transition is found at low temperatures. The chiralities of the magnetic structures were determined from neutron powder diffraction data. In the vicinity of TN 2-dimensional magnetic short range order is found. The solid solution Bax Sr(1- x) LaMnO4 crystallizes in the K2 NiF4 structure, space group I 4/ mmm . The magnetic structures were determined from neutron powder diffraction experiments, where Néel ground states were found for x ≤ 0.20. The magnetic moment magnitude decreases with increasing x. The disappearance of magnetic long range ordering for x > 0.20 is rationalized in terms of intralayer and interlayer magnetic coupling constants. 2-dimensional magnetic short range order is found in the vicinity of the Néel temperatures. Polycrystalline Li4 MgReO6 was prepared and investigated by means of neutron powder diffraction experiments. Li4 MgReO 6 crystallizes in space group C2/m and forms an ordered rock salt structure. The Re6+ sublattice consists of distorted face-sharing tetrahedra. Neutron diffraction, heat capacity, bulk magnetic susceptibility, magnetic relaxation and muon spin relaxation measurements reveal a spin glass ground state with Tf = 12K. The spin glass ground state is rationalized in terms of Li-Mg disorder. At 2.5K all magnetic moments are static.

abstract: Doctor of Philosophy (PhD)


title: Silicone-protein interactions

contributor:
Brook, Michael A.
Chemistry

subject: Chemistry Chemistry

abstract: Novel organofunctional silicones have been proposed as materials for the formulation of protein delivery systems. The efficacy of such systems to deliver proteins orally, without loss of their activity has been demonstrated. Furthermore, normal (non-functional) silicones failed in exhibiting an analogous protein protective role. The functionality on these novel silicones was obviously crucial in formulating efficient protein carriers. Therefore, the interaction of these organofunctional silicones with proteins has been examined against normal silicones. The extent and strength of the silicone-protein interaction has been revealed from model surface studies at solid/liquid interfaces and also from emulsion stability studies at liquid/liquid interfaces. It has been suggested that the silicone functionality facilitates the interaction between the two species while it may also lead to self crosslinking of the silicone chains using the protein as a template. Finally, evidence of the effect of liquid silicones on the protein biological integrity has been obtained to further prove, from a biological perspective, the suitability of liquid silicone-based delivery systems.

abstract: Doctor of Philosophy (PhD)


title: A wavelength monitor based on electroabsorption in quantum well waveguide photodiodes

contributor:
Jessop, P. E.
Engineering Physics

subject:
Engineering Physics
Engineering Physics

abstract: A wavelength monitor, based on p-i-n quantum well waveguide photodiodes, and its application to fiber Bragg grating strain sensor have been demonstrated. Ridge waveguide photodiodes with five different quantum well structures have been de signed, fabricated and characterized. In a wavelength monitoring system that employed a single-segment photodiode, the waveguide photodiode was used as either a tunable edge filter or a wavelength selective photodetector. A wavelength resolution of 1 pm with an operating range of 18 nm was achieved with a GaAs/AlGaAs multiple quantum well device. In a wavelength monitoring system that employed a pair of in-line waveguide photodiodes, the photocurrent ratio of the two photodiodes varied linearly with wavelength in a region near the absorption band edge. A wave-length resolution of 0.4 pm was achieved with InGaAs/GaAs quantum well devices for TE-polarized light with intensities of about 30 μW and a signal averaging time of 0.2 seconds. An operating range of 40 nm was obtained by voltage tuning of the quantum wells. The photocurrent ratios in the in-line waveguide photodiodes were also used to determine the absorption coefficients of the photodiodes. The shifts of the exciton peak positions with the applied bias voltage showed fairly good agreements with the predictions of a variational theory. The photocurrent ratio of the in-line quantum well waveguide photodiodes showed strong polarization dependence. However, the separation between the absorption edges for the TE and TM polarizations was so large that this device could be used in the wavelength range near the absorption edge of the TE component even in the presence of a large TM component in the input. An optical fiber Bragg strain sensing system, that consists of a superluminescent diode, a 2 x 2 fiber coupler, a fiber Bragg grating and the waveguide detector, was assembled to demonstrate the application of the developed wavelength monitor. A strain resolution of 5 microstrain has been obtained with the fiber Bragg grating strain sensor. The grating strain sensor shows a linear response over a range of ±2500 microstrain.

abstract: Doctor of Philosophy (PhD)


title: Perceptual asymmetries in a diatonic context

contributor:
Platt, J. R.
Psychology

subject: Psychology Psychology

abstract: When investigating the perceived similarity of two musical stimuli, systematic asymmetries emerge which depend on the nature of the two elements being compared, relative to the musical context in which they appear. At the level of individual tones, Krumhansl (1979) found that if the order of presentation was diatonic/nondiatonic (relative to a tonal context), similarity ratings were lower than if that order was reversed. She concluded that when a change results in an element becoming less stable in terms of its position on the tonal hierarchy, similarity perception will be lower than if a change increases its stability. At the level of melodies, Bartlett and Dowling (1988) obtained a similar result, but claimed the asymmetry was due to violations of scalar structure, having little or nothing to do with the tonal hierarchy. To test between these different accounts, a series of experiments was conducted in which pairs of diatonic melodies were presented for similarity ratings. Each melody consisted of a context sequence and a target sequence. The context sequences were designed to promote either a C-major or a D-minor tonal hierarchy. These respective keys share similar notes in their scales, but the tonal hierarchies are inverted with respect to one another. According to Krumhansl's account of the asymmetry, noticeable changes in one key context should not be noticeable in the other, due to the reversal in stability of the component tones of the alteration. According to Bartlett and Dowling, no differential sensitivity should be observed, since all changes were within the scale structure of both contexts. In the first experiment, repetition of the tonic was employed as the key-instantiating stimulus, the result being that strong asymmetrical perception arose, both on the measures of similarity ratings, as well as alteration detection ability. Subsequent experiments employed triadic contexts (suggested by Krumhansl and others to be strongly key-instantiating), and note-frequency controlling contexts (to rule out the possibility of note repetition playing a role in the similarity ratings). The results supported the hypothesis that asymmetric perception is a result of the dynamic tone quality differences between scale degrees in a tonal melody. Two subsequent control studies ruled out the possibility of target sequences themselves being responsible for the asymmetries, and confirmed that listeners perceived the melodies in the keys specified in the experiment. A model based loosely on Tversky's explanation of asymmetric perception was put forth to explain these data, as well as those of Bartlett and Dowling.

abstract: Doctor of Philosophy (PhD)


title: Drug-induced ataxia: Effect of the self-administration contingency

contributor:
Siegel, Shepard
Psychology

subject: Psychology Psychology

abstract: Some studies have demonstrated that the effects of a drug may be different, depending on whether the drug is self-administered or passively received by the subject. Most of the studies which have examined this phenomenon have not examined the effects of a drug following each of a series of administrations. Moreover, the mechanism mediating differences between self-administered and passively received drugs has not been determined. The present experiments used a yoked-control design to examine the development of tolerance to the ataxic effects of heroin and of ethanol in rats that self-administer the drugs and rats that passively received them. Results demonstrate that rats that passively received heroin, but not those that self-administered the drug, were significantly impaired following the initial administrations. During the first administration sessions, rats that self-administered ethanol were as impaired as their partners that passively received, but within a few sessions self-administering rats developed tolerance to the ataxic effect of the ethanol, while their yoked partners did not. The results also suggest that the faster tolerance development in rats that self-administered ethanol may have been mediated by differences in Pavlovian conditioning in these subjects, which demonstrated larger compensatory conditional responses in the form of "hypertaxia" than did their yoked partners. The results indicated that some component of the self-administration process contributed to the Pavlovian conditioning, and hence, faster tolerance development, of self-administering animals. The data suggest that studies in which drugs are passively received may overestimate the dose that is necessary to produce tolerance in self-administering animals. Models based on such studies, then, may require modification before they are applied to situations which involve self-administration of drugs.

abstract: Doctor of Philosophy (PhD)


title: Assessing the status of the endangered North Atlantic right whale using genetic and demographic data

contributor:
White, Bradley N.
Biology

subject: Biology Biology

abstract: Nineteen years of monitoring the highly endangered North Atlantic right whale (Eubalaena glacialis ) has led to the photo-identification of 388 individuals of which 283 were alive in 1997. To assess the status of the population, microsatellite markers were developed and used to establish individual-specific genetic profiles for 209 whales. Genetic profiles based on nine microsatellite loci and mitochondrial control region haplotypes were used to examine the population for evidence of inbreeding and to assess the current levels of genetic variability. At the population level, genetic variability was found to be lower than that reported for other large-bodied cetaceans, including the closely-related South Atlantic right whale. No evidence was found to indicate that the low genetic variability is the result of the most recent population bottleneck (19th century). Rather, the loss of genetic variability appears to have occurred over several hundred years, starting as far back as the 16th century. To examine the current population for evidence of inbreeding, the nature of the mating system was identified and used to estimate the effective number of breeders in the population. Based on a promiscuous mating system, the effective population size is estimated at between 103 and 154, which places the ratio of the census population size to the effective population size within those reported for other large-bodied mammals. Despite the random nature of the mating system, population structuring was identified between calves born to two groups of females that differ in their use of nursery habitat. The identification of two reproductively discrete populations suggests the existence of two mating areas for the North Atlantic right whale population. Although mating is not entirely random within the population, no evidence of inbreeding was detected in the population. Mating pairs were no more related than unrelated whales (Rxy = 0.0007 ± 0.24 versus -0.035 ± 0.28). While 74% of females produced at least one calf during a period of 17 years, only 55% had multiple birthing events. The failure of the population to increase in size during the past few hundred years may reflect an overall reduction in the reproductive fitness of females that may be associated with the historic loss of genetic variability. The ability of the population to remain at a stable size (∼300) throughout the past 400 years suggests that the current decline in the size of this population is the result of more contemporary influences. The combination of contemporary influences, such as resource shortages and accidental mortality, with the low intrinsic calving rate, appear to be compromising the long-term persistence of this species. (Abstract shortened by UMI.)

abstract: Doctor of Philosophy (PhD)


title: Cloning of the SH2-containing inositol 5-phosphatase (SHIP) and characterization of its role during erythroid differentiation

contributor:
Whyte, P.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: The SH2 containing inositol polyphosphate 5-phosphatase (SHIP) has been implicated in the negative regulation of growth and differentiation of multiple hematopoietic cell types. In this thesis, I describe the cloning and biochemical characterization of the human SHIP cDNA. SHIP expression was found to be restricted to cell lines of hematopoietic origin at both the protein and RNA level. The K562 erythroleukemia cell line was identified which lacked detectable SHIP protein and message. The absence of endogenous SHIP in K562 cells provides a useful in vitro system to study the contribution of SHIP to the process of growth and differentiation in this cell line. Hemin stimulation of the K562 cell line results in the induction of an erythroid differentiation program. When stably overexpressed in K562 cells, SHIP was found to be constitutively tyrosine phosphorylated and associated with endogenous Shc, Grb-2 and Bcr/Abl. Overexpression of SHIP did not affect the overall growth rate of the cells but resulted in decreased synthesis of hemoglobin protein and [varepsilon]-globin mRNA in response to hemin stimulation. This effect was not due to increased cell death or cell cycle arrest in the SHIP-expressing lines following hemin stimulation, but was likely the result of an impaired differentiation program in these cells. Mutational studies indicated that SHIP must retain both an intact catalytic domain and Shc binding site to efficiently inhibit K562 erythroid differentiation.

abstract: Doctor of Philosophy (PhD)


title: Effects of arterial vasodilators on cardiovascular hypertrophy and sympathetic activity in normotensive Wistar and spontaneously hypertensive rats

contributor:
Lee, R.M.K.W.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: In spontaneously hypertensive rats (SHR), treatment with the arterial vasodilator minoxidil does not prevent or attenuate the progression of cardiovascular hypertrophy despite blood pressure control, and the reason is generally unknown. The purpose of this study, was to examine temporal changes of cardiac and mesenteric arterial structure with respect to changes in volume load and cardiac and arterial sympathetic activity, during chronic treatment of normotensive and SHR with minoxidil alone, or in combination with the diuretic hydrochlorothiazide (HCTZ). The hypothesis to be tested is that an increase in the sympathetic activity and/or cardiac and intravascular volume is involved in causing these structural changes. In normotensive rats, minoxidil induced (i) right ventricular hypertrophy (RVH), (ii) eccentric left ventricular hypertrophy (LVH), (iii) medial hypertrophy of the superior mesenteric artery, (iv) intravascular volume expansion, (v) increases in cardiac filling pressures, (vi) increases in ventricular and arterial norepinephrine turnover rates. In SHR, minoxidil (i) decreased blood pressure, (ii) potentiated RVH, (iii) caused the development of eccentric LVH superimposed on the preexisting hypertrophy, (iv) increased the lumen of the superior mesenteric artery, (v) prevented further increases in medial hypertrophy of the large and small mesenteric arteries, (vi) induced intravascular volume expansion, (vii) increased ventricular but decreased arterial norepinephrine turnover rates, and (viii) increased elastin content and decreased elastase activity in the large conducting vessels (aorta, superior mesenteric artery). In SHR and normotensive rats, concomitant diuretic treatment prevented intravascular volume expansion, caused concentric LVH rather than eccentric LVH and no longer increased the medial and luminal areas of the superior mesenteric artery. These results suggest that there are regional differences in the response of the cardiovascular system to minoxidil in SHR and normotensive rats. Some of these differences may relate to differences in regional sympathetic activity, whereas volume load appears to play a modulatory role.

abstract: Doctor of Philosophy (PhD)


title: LATE PLEISTOCENE PALEOCLIMATES IN NORTH AMERICA AS INFERRED FROM ISOTOPIC VARIATIONS IN SPELEOTHEMS

contributor:
Schwarz, H.P.
Ford, Derek C.
Geology

abstract: Doctor of Philosophy (PhD)


title: Liquid Cross-Flow-Induced Vibration

contributor:
Weaver, D.S.
Mechanical Engineering

abstract:
Modern tube and shell heat exchangers designed with the existing standards may be susceptible to damage as a result of excessive tube vibrations caused by the shell-side flow. The present study was undertaken to further our understanding of the liquid cross-flow-induced vibrations of a tube array of contemporary interest.

An experimental facility to study these phenomena was designed and built. The experiments were conducted using this specially designed water tunnel having a 305 x 305 mm working section. The tube bundle was a parallel-triangular array with pitch to diameter ratio of 1.375. The array was 6 rows deep with 5 tubes in each row. Ten tubes at the centre of the array were designed to be flexibly mounted. The natural frequency and damping of these tubes could be controlled over a range of values. The rest of the tubes were rigidly fixed in the test section.

The critical velocity for instability of tubes located in the third and fourth rows was established and the stability for the array was determined. The present results indicate that extrapolation of the stability boundary proposed from results obtained in wind tunnels, for arrays of the same geometry yield unconservative predictions. A study of the flow velocity power spectra indicate that no flow periodicity could be detected in the flow before the critical velocity was reached. Detuning of adjacent tubes was proven to have little effect on the stability threshold of a tube located in the third row.

The results of the present study were compared with data in the published literature. It is seen that the present results lie below the majority of the proposed stability boundaries.

abstract: Master of Engineering (ME)


title: In vivo electrical stimulation of motor nerves

contributor:
Bruin, H. de
Electrical and Computer Engineering

abstract: Stimulus waveform parameters and stimulation protocols are fundamental to the use of electrical stimulation in medical applications. This thesis presents new simulation and experimental procedures that for the first time can quantify the effects on nerve fiber recruitment patterns of variable stimulus waveform parameters, such as pulse width changes in the stimulation protocol with respect to electrode orientation. The study of the effect of variable electrical stimulus waveform parameters and stimulation protocols is important from the perspective of therapeutic and diagnostic medicine. Variations in the stimulus waveform such as stimulus pulse width have been shown to offer some promise in allowing for selective recruitment of nerve fibers and motor units based on nerve fiber diameter. The degree of selectivity achievable has not however been quantified under any stimulus electrode protocol. Standardization of electrodiagnostic techniques such as motor unit number estimation would also benefit from a quantified study of nerve fiber recruitment patterns under different stimulus pulse width conditions. Changes in the stimulus electrode orientation result in marked changes in the muscle response during conduction velocity tests. This phenomenon has not been investigated in any systematic fashion. In order to quantitatively study these effects, both theoretically and experimentally, a number of tools and techniques had to first be selected or developed that include: (i) a sufficiently realistic model of the myelinated nerve fiber and nerve trunk that, for the first time in electrical nerve excitation studies, incorporates information associated with anatomically consistent fiber diameter distributions; (ii) a more realistic model of the tissue surrounding this nerve trunk that includes electrical anisotropy; (iii) a field simulation technique used to determine the potential fields at the nerve fiber surfaces (with different diameters and electrode distances) resulting from stimulus pulses with different pulse widths; (iv) two novel sets of experiments, the first of which is used to stimulate a nerve trunk in vivo and from the resulting electrical response, determine the diameters of the nerve fibers that have "fired" under conditions of variable stimulus pulse width, the second of which is used to study the effect of electrode orientation on the stimulus response. The techniques outlined above facilitate a quantitative comparison between experimental and simulation results for the stimulus current pulse width studies as opposed to purely qualitative comparisons that have been reported in the literature. A novel instrument design prototype is presented based on the electrode orientation experiment, that can be used to standardize stimulus electrode orientation for multiple EMG (Electromyography) tests performed on a single subject at different times.

abstract: Doctor of Philosophy (PhD)


title: The molecular dynamics and reactivity of transition metal and main group eta-1-indenyl complexes

contributor:
McGlinchey, M. J.
Brook, Michael A.
Chemistry

subject: Chemistry Chemistry

abstract: The molecular dynamics of a landmark compound in fluxional organometallic chemistry, (η5 -C5 H5 )Fe(CO) 2 (η1 -C9 H7 ), 1.9 , were reexamined by use of 2D-EXSY and single selective inversion NMR techniques. Contrary to an important early report, the present work establishes unambiguously that this compound is quasi-fluxional. The barrier (ΔG [double dagger] ) to [1,5] iron shifts in 1.9 is 20 ± 2 kcal mol-1 and the intermediate isoindene, 1.10 , is sufficiently long-lived so as to yield a [4+2] cycloadduct, 2.2 , with tetracyanoethylene. The tris(σ-indenyl)silanes, (1-C9 H7 ) 3 SiX where X = H, Me or allyl (3.18, 3.19 and 3.20 , respectively) undergo a series of [1,5] silatropic shifts which interconvert the RRR, RRS, RSS , and SSS isomers, where the R and S labels refer to the absolute configuration of C(1) in each indenyl ring. The molecular dynamics of these tris(σ-indenyl)silanes have been elucidated by means of selective inversion experiments together with 2D-EXSY data; the barrier (ΔG [double dagger] ) to [1,5] silicon shifts in these compounds is ∼24 kcal mol-1 , and the exchange pathways between indenyl sites can be conveniently mapped onto a hypercube. Moreover, each of the three tris(σ-indenyl)silanes examined yielded the corresponding triple Diels-Alder adduct, 3.21, 3.22 and 3.23 , respectively, upon reaction with tetracyanoethylene. Despite the steric demands of the ligands in these tris(σ-indenyl)silanes and tris(benzonorbornyl)silanes, it has been demonstrated that chemical reactions can still be carried out at the silicon centers in these molecules. Whilst examining the factors which affect silicon migrations in indenylsilanes, the silicon-substituted dibenzo[a,d ]fulvalene, 4.24 , was unexpectedly obtained in low yield from the reaction of indene and chlorotrimethylsilane in the presence of excess base. This compound has been characterized by use of both NMR spectroscopy and X-ray crystallography, and can be rationally prepared in acceptable yield starting from the dimer of trimethylsilylindene, 4.31 . In continuation of these studies, a series of indenylsilanes bearing methyl substituents (4.7 ) and a π-bonded chromium fragment (4.38 ) on indene have been prepared, as has a compound in which a dicobalt cluster is situated adjacent to the migrating silicon center (4.52 ). Data obtained from 2D-EXSY and single selective inversion NMR studies involving these complexes demonstrated that such structural perturbations have little impact on the barrier to [1,5] silicon shifts (ΔG[double dagger] ∼24 kcal mol-1 ) in this class of compounds. Finally, in an attempt to generate a compound capable of participating in intramolecular Diels-Alder reactions, the indenylsilanes, 5.15-5.17 , were prepared; the quasi-fluxional nature of this molecular system was revealed by 2D-EXSY NMR. Preliminary reactivity studies demonstrated that the unactivated dienophiles tethered to the indenyl framework in these molecules do not undergo the desired intramolecular [4+2] cycloaddition process.

abstract: Doctor of Philosophy (PhD)


title: Messianic Ethics: Jesus' Kingdom-of-God Proclamation and the Appropriate Response

contributor:
Meyer, Ben F.
Religious Studies

subject:
Biblical Studies
Biblical Studies

abstract: How are the eschatology and ethics related in Jesus' proclamation of the kingdom of God and in the response to it that he hoped to win from Israel? How is the ethical dimension of the intended response formed or informed by the kingdom of God? In the history of scholarship the search for the coherence between Jesus' eschatological message and the response to it that he intended to win inevitably raised the question of the relation between "kingdom" and ethics. Albrecht Ritschl's influential view affirmed the closest bond between them: the kingdom of God is to be realized in and by human ethical action. This way of stating the relationship of shattered by the compact work of Johannes Weiss on Jesus' proclamation of the kingdom of God. If it is not possible simply to follow Weiss (or Schweitzer, who followed up on and refined the position of Weiss). It is also impossible to bypass him. Therefore in chapter one I outline the position of Ritschl and the response of Weiss' influential exposition of the kingdom of God. This is followed by an attempt to examine the relation between eschatology and ethics in the work of representative scholars from the past one hundred years. This interpretation of the kingdom of God in Jesus' proclamation depends significantly on what is presupposed about the resourced from which he drew in making his proclamation and carrying out his mission. There I survey Jewish writings with the ultimate aim of determining what was clearly important for Jesus. Furthermore, these sources give evidence of a relation between (eschatological) promise and appropriate ethical response. In the interpretation of Jesus' Kingdom-of-God proclamating attention has been directed either to eschatology or to ethics at one time the primary focus was on the human ethical response (e.g. Harnack), at another time on the activity of God (e.g. Jogannes Weiss). If it is true that eschatology and ethics exist in religion in the proclamation and teaching of Jesus, it follows that they may only be properly or clearly understood in a study that examines them in their relationships. This calls for a critical correlation of Jesus' eschatological message and his ethical teaching. Jesus' eschatological proclamation and the intended ethical response become concrete only with a recovery of the purposes of Jesus bearing on the whole people, Israel, to whom he came (chapter three). In chapter four I examine Jesus' kingdom-of-God proclamation defined more sharply and fully in the context of his mission and death as this was expressed in the esoteric teaching of his disciples. And in this teaching the connection between Jesus' own destiny and his ethics of discipleship is emphasized. A reasonably accurate comprehension of the ethics of Jesus depends on a reasonably accurate recovery of the whole historical figure that he was. The present study accordingly pays attention to the historical bases for the understanding of Jesus' ethical teachings whether in the public forum-or in the more intimate circles of his discipleship.

abstract: Doctor of Philosophy (PhD)


title: Three-dimensional finite element analysis of viscoelastic flow

contributor:
Hrymak, A.N.
Vlachopolous, J.
Chemical Engineering

abstract: 3-D numerical analysis of a viscoelastic flow is a necessity for better understanding of viscoelastic fluids and viscoelastic flow. It is important both from the scientific and technological points of view. Analysis of viscoelastic flow is a difficult task as it is associated with the problems arising from intrinsic complexity of the fluid. Progress in the area of 3-D analysis of viscoelastic flow has been further hindered by the increase in the size of the problem and number of variables. The outlet boundary condition for 3-D flow of a viscoelastic fluid is another problem. Segregated methods were used to solve the creeping flow formulation of the duct flow to save computer time and memory. A pressure correction method was selected and compared with the fully coupled method. A 3-D and 2.5-D segregated algorithm were proposed using the modified Phan-Thien Tanner constitutive equation and the EVSS method to decouple the calculation of stresses from the flow kinematics. Results from the 2.5-D algorithm were verified by comparison with the reported results from literature. Results for cases of high Wi were obtained and it was shown that for MPTT fluid, the intensity of the secondary flows becomes independent of Wi at high Wi. The effects of Re on the secondary flows were also studied and new patterns of secondary flows involving up to eight vortices in each quarter were reported. Results from the 2.5-D analysis were compared with the results of a 3-D algorithm in the analysis of the viscoelastic flow in straight ducts. Different cases of boundary conditions were studied and observations are reported. It is reported for the first time that a deviation from a fully developed solution occurs near the outlet. The problem of the destruction of the vortex pattern and the consequent increase in the primary flow velocity component were then analysed. It was established that the fully developed flow solution is a valid solution for the 3-D formulation of the problem and the problem arises from a combination of the decoupling of the stresses and imposing outlet boundary conditions. The 3-D algorithm was further evaluated for the cases of flow in complex geometries, using two test cases from the literature. One of the cases involved a converging duct and the other involved a 4:1 abrupt contraction. Results from 3-D and 2-D planar analysis were compared with the reported experimental results.

abstract: Doctor of Philosophy (PhD)


title: Experimental and analytical study of a frustum confining vessel

contributor:
Stolle, Dieter F.E.
Civil Engineering

subject:
Civil Engineering
Civil Engineering

abstract: A Frustum Confining Vessel (FCV) was developed by McMaster University and Berminghammer Foundation Equipment Ltd., which provides an environment for the testing of reduced-scale piles (physical model). This vessel is intended to produce stress distributions within sand specimens, which resemble field conditions, however at a smaller geometric scale. This thesis presents the findings of the experimental and analytical investigations conducted on the FCV device. A technique for measuring normal stresses in dry sand is developed, and the stresses and displacements measured at specific locations within the sand specimens are used to calibrate the finite element model. Finite element simulations are used to evaluate different aspects of the responses, which cannot be directly measured in the experiments. The fundamentals of dimensional analysis are reviewed and a set of primitive variables for the pile-soil system is presented. Using the Buckingham-π theorem, a derived set of dimensionless groups is thereby proposed for the study of pile-soil interaction. The scaling factors necessary for the extrapolation of results from model to prototype conditions are obtained via similarity analysis. It is suggested that the lack of gravity scaling in the FCV device does not introduce significant distortions in the physical model provided that stress distributions, particularly horizontal stresses, are properly controlled by FCV loading. In relation to physical modeling of piles, a criterion for the acceptance of testing conditions is established, and the suitability of the current device is assessed in terms of the mentioned criterion. It is found that the current device does not completely meet the acceptance criteria. The improvement on testing condition is thereby sought by redesigning the vessel's shape. Alternative shapes for the vessel are investigated by means of finite element modeling. A redesigned shape, which offers optimal stress conditions for the purposes of physical modeling, is presented.

abstract: Doctor of Philosophy (PhD)


title: Effect of Feedback Training and Knowledge of Results on Discrimination of Skin Conductance Responses

contributor:
Roberts, L.E.
Psychology

subject: Psychology Psychology

abstract: The ideomotor theory of visceral learning predicts that the ability to control a visceral response and the ability to detect its occurrence should be correlated. The experiment reported in this thesis examined the effect of training subjects to control sudomotor responding on ability to detect the occurrence of this response. While training was found to facilitate discrimination, the correlation between control and discrimination was not significantly different from zero. It was suggested that one need not abandon ideomotor theory, but realize that other influences may obscure the relationship expected. Examples of possible influences are described.

abstract: Master of Arts (MA)


title: The influence of organizational culture and gender salience on managers' decision-making styles

contributor:
Zeytinoglu, Isik Urla
Business Administration

subject: Business Administration, Management, and Operations

abstract: A number of studies have established that women in managerial positions are more likely to be participative (involving subordinates in their decision-making) than their male counterparts. The present research was designed to address the question of whether certain antecedent conditions--in particular, features of organizational culture--affect the degree to which women and men differ in participative behaviour. This question is important for several reasons: scientific understanding (since gender-based differences, especially behavioural ones, are little understood), development of organizational theory, and greater understanding for practitioners of how participative managerial styles can be fostered. The research design is a field study, utilizing a combination of quantitative and qualitative measures. While this design created a number of constraints, I believe that it was useful in terms of trustworthiness of the findings. The naturalistic setting and the opportunity to triangulate the findings were among the advantages of the research design; disadvantages included a necessarily small sample size, and purposive sampling limited by the ability and willingness of organizational gatekeepers and members to take part in the research. The central focus of investigation was whether and how organizational culture influences participative behaviour for women managers. The initial model proposed that in traditional organizations, gender salience is heightened for women in managerial roles because of their scarcity and because managerial stereotypes tend to involve traits generally perceived (in North American culture) as masculine. Findings showed that heightened gender salience accounted for at least part of the observed gender difference in participative behaviour. The findings of the research at first seemed paradoxical, since the organization which was the least traditional (i.e., the most woman-friendly in its policies) was also the one in which gender salience seemed to be high compared to the rest of the sample. This finding led to a modification of the original model to a more complex, time-dependent understanding of the process under study.

abstract: Doctor of Philosophy (PhD)


title: Sexual selection in northern water snakes, Nerodia sipedon sipedon: Examination of the mating system and correlates of male reproductive success using microsatellite DNA markers

contributor:
Gibbs, H.L.
Weatherhead, P.J.
Biology

subject: Biology Biology

abstract: Determining how sexual selection operates on males and females can lead to a better understanding of the evolution of specific traits that influence fitness. Of the few studies that have investigated sexual selection in reptiles, most have relied on estimates of mating success from field observations, without knowing whether these behavioural data reliably reflect true reproductive success. However, recently developed molecular tools allow researchers to more accurately assign parentage and thus, measure reproductive success. In this study, I isolated ten northern water snake (Nerodia sipedon ) microsatellite loci which were then used to conduct genetic studies on wild populations of this species. My major findings include that: (1) There is fine-scale (<2 km) genetic structure among three water snake populations. (2) Based on paternity assignments involving approximately 200 males and 800 offspring, more than half of the litters were multiply sired, which is lower than previous estimates for this species, and the incidence of multiple paternity was greater where females were more clumped and male competition for mates more intense. (3) Estimates of mating success based on field observations do not reliably predict genetically-determined measures of reproductive success. (4) Securing additional mates resulted in a marginal increase in reproductive success for females, but a large increase for males: the opportunity for sexual selection was more than 70 times greater for males than females. (5) Small male body size was not correlated with reproductive success and therefore, the evolution of female-biased sexual size dimorphism cannot be explained by a reproductive advantage of small males. However, males who were more "active" (i.e. more field observations) had higher reproductive success. The results of this study support the view that, to effectively study sexual selection in many reptile species, it is necessary to measure reproductive success using genetically-based techniques.

abstract: Doctor of Philosophy (PhD)


title: Rates of bone loss in postmenopausal women: Relationship to calcium intake, calcium absorption, serum estrogen, body mass and physical activity

contributor:
Webber, C. E.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: A prospective 2-year study was designed to test the hypothesis that 3 core factors influence the postmenopausal decline in bone mineral: adequate supply of calcium to the skeleton, endogenous estrogen production by lean and fat tissue mass, and mechanical stress imparted by physical activity and body mass. The rate of change in bone mass (ΔBMD) was established for 61 postmenopausal women from semi-annual measurements of bone mineral density (BMD) at the proximal femur and lumbar spine using dual energy X-ray absorptiometry (DXA). Whole body BMD and body composition were also assessed annually using DXA. Serum estradiol was determined at baseline by radioimmunoassay. Calcium intake was evaluated using a food frequency questionnaire. Calcium absorption was measured using a single isotope technique. Grip strength was measured using a Jamar hand dynamometer. Aerobic fitness was determined using a submaximal 1-mile walk test. Habitual daily activity was assessed using a portable accelerometer. At baseline, the strongest associations were between BMD and body mass values. These explained 22 to 25% of the variance in BMD. Estradiol was an independent predictor of BMD of the whole body. No physical activity variable was independently predictive of BMD. Of the dietary variables, only tea consumption was independently predictive of BMD at the femoral and whole body sites. With age, bone loss was attenuated. At the lumbar spine, ΔBMD was also positively influenced by lean mass, weight gain, protein intake and increased calcium intake. The contribution of estradiol was borderline (p = 0.06). Weight gain was similarly influential at the femur. There was no positive influence of any physical activity measure on ΔBMD at any site. Lean mass and weight gain had the greatest positive influence on BMD and ΔBMD. A hormonal rather than mechanical explanation was favoured. Trabecular bone may also be responsive to dietary perturbations.

abstract: Doctor of Philosophy (PhD)


title: An investigation of shaft current in a large sleeve bearing induction machine

contributor:
Findlay, Raymond David
Electrical Engineering

abstract: Irregularities in the magnetic circuits of machines may result in spurious voltages that lead to shaft currents through the shaft, bearings, bearing supports and closing through the machine framework. The IEEE Standard Test Procedure for Polyphase Induction Motors and Generators discusses the shaft current and presents a measurement method for recording either the voltage across the ends of the shaft or the current. This thesis discusses an alternative measurement approach and its application to the identification of shaft current in a large induction machine. Possible causes of shaft current are discussed. The magnetomotive force-permeance approach is used in the determination of the possible causes. An eight pole 2611 kW oil ring lubricated induction motor which exhibited signs of bearing damage due to shaft current was used in a series of experiments conducted to evaluate the cause(s) of the bearing damage. The new method of shaft current measurement, known as the Rogowski Coil Method, was applied to this machine. The experiments included oil analysis and microscopic analysis of the bearing. The experiments showed that the main cause of the shaft current is the presence of joints between stator lamination segments. Saturation accentuates the magnitude of shaft current. The Rogowski coil method is shown to be reliable; it does not disturb the shaft current conducting circuit. Furthermore, it requires little maintenance, unlike the ammeter/brush method. Oil ring delivers oil to the bearing. An oil film will develop between the shaft journal and the bearing. The oil film acts as an insulator against shaft current. It is thus important that sufficient quantity of oil is delivered to the bearing and an oil film is developed as quickly as possible to minimize the shaft current. Hence, the performance of the oil ring is studied. The Rogowski method is used to study the performance of the oil ring. The oil ring is determined to slip early with respect to the shaft. As a result, the amount of oil delivered to the bearing is determined to be less than calculated. The proposed method is simple, reliable and less labor intensive than other methods. Patent application for this method is being filed. A method of minimizing shaft current is described following the experimental work to determine the cause(s) of the shaft current. Patent application for this method is being filed. The present on-line monitoring system utilizes the spectral analysis of the stator current to determine stator and rotor faults in alternating current machines. The Rogowski coil method can be used as an alternative on-line monitoring system for such faults.

abstract: Doctor of Philosophy (PhD)


title: Measuring lead, mercury, and uranium by in vivo X-ray fluorescence

contributor:
Chettle, David R.
Physics and Astronomy

subject:
Astrophysics and Astronomy
Physics
Astrophysics and Astronomy

abstract: X-ray fluorescence (XRF) has been demonstrated to be a useful technique for measuring trace quantities of heavy metals in various tissues within the body. This thesis investigates a means of improving the measurement of lead in bone, as well as increasing the existing sensitivity of measuring kidney mercury content. The XRF measurement of uranium is also explored. This work assesses the feasibility of a normalisation method for the 57 Co/90° system, in relating detected signal to the lead content of the sample. The feasibility of normalisation has been shown, which reduces subject dose and improves system transportability, as well as removes subjectivity, by eliminating the need for acquiring planar x-ray images of the measurement site. In the measurement of renal mercury concentrations, a gain in sensitivity increasing the x-ray tube operating voltage of the current system is investigated. It found that 250 kV, rather than 175 kV, and a titanium rather than uranium filter, results in a 2.5 ± 0.2 times gain in sensitivity. This potential improvement could have profound clinical implications for the accuracy of occupational monitoring, and for assessing whether there is a quantitative relationship between biological fluid levels and mercury content in this critical organ. The XRF measurement of bone uranium content is also explored. Both source-excited and polarised systems have been developed, however, the sensitivity is currently beyond that which is useful for occupational monitoring of exposure to this toxin. The particular case of measuring uranium in survivors of "Friendly Fire" incidents (from Operation Desert Storm) is investigated, and the first detectable quantity of uranium has been observed in a member of this cohort, with the XRF system designed and built during the course of this work.

abstract: Doctor of Philosophy (PhD)


title: Linewidth enhancement factors of short external cavity semiconductor lasers

contributor:
Cassidy, D.T.
Engineering Physics

subject:
Engineering Physics
Engineering Physics

abstract: This thesis describes the development of a method for measuring the tuning of the emission frequency of semiconductor lasers. This method employs a short external cavity (SXC) mirror, as an external optical feedback element, to alter the resonant condition of the lasers. The experimental system, which includes an SXC laser module constructed out of a flexure mount concept, was derived from this method. The system was used to make measurements of the frequency tuning of InGaAsP multi-quantum well lasers. Linewidth enhancement factors of these lasers were calculated from the experimental data. It was found that the linewidth enhancement factors of these lasers depend on the wavelengths of emission and are fairly independent of the output powers. It was also found that the linewidth enhancement factors of these lasers decrease as the band gap of the barriers of the quantum wells increases.

abstract: Doctor of Philosophy (PhD)


title: Policy making performance, policy change, and political institutions: The formulation of an environmental policy for the agricultural sector in France, the United States and Canada

contributor:
Coleman, William D.
Political Science

subject:
Political Science
Political Science

abstract: This dissertation examines the performance of policy makers in the environmental sector. It is suggested that policy makers perform at a high level when they are capable of making changes in existing policies. Specifically, policy makers must be able to expand the reach of their country's environmental policy to the agricultural sector and increase the intrusiveness as well as the comprehensiveness of policy instruments to prevent the intensification of farming from causing serious damage to the environment. When performing at a high level, however, policy makers should be able to achieve these policy changes without endangering the economic viability of agriculture. The general performance of policy makers was found to be higher than expected. It is argued in this dissertation, however, that France performed at a higher level than the United States which itself performed at a higher level than Canada. Variations in institutional arrangements explain these differences. In France, the European Union empowered environmental actors pressing for the adoption of intrusive environmental regulations for the agricultural sector. But this pressure was mediated by a corporatist policy network in a manner that minimized the cost of the policy to farmers. In contrast, the pressure for the adoption of stringent environmental regulations in the United States entered a federal arrangement in which state-civil society relations were regulated by pluralist policy networks. This enabled swift policy changes that conflicted with the interests of farmers in several states. Nevertheless, the American federal setting worked better than that of Canada where the central government failed to adopt a significant environmental policy for the agricultural sector and where environmental standards from one province to the next vary enormously.

abstract: Doctor of Philosophy (PhD)


title: The molecular mechanism of transcriptional activation by the peroxisome proliferator activated-receptor alpha

contributor:
Capone, John P.
Biochemistry

subject: Biochemistry Biochemistry

abstract: The peroxisome proliferator-activated receptor (PPARα) is a member of the nuclear receptor superfamily, a growing class of transcriptional activators. Many of these proteins, including PPARα, function as intracellular receptors for hormones and upon the binding of agonist, activate the transcription of target genes. PPARα is an integral regulator of fatty acid metabolism and as such is activated by fatty acids resulting in the stimulation of the expression of genes involved in the release, cellular uptake, and β-oxidation of free fatty acids. The research presented in this thesis details the discovery and characterization of mechanistic aspects by which PPARα mediates the transcriptional activation of target genes. Transcriptional activators bind to specific DNA binding sites in the promoter region of target genes to effect changes in the rate of transcription. Included in the presented work are the discovery and the characterization of protein-DNA interactions that are involved the activation of transcription by PPAR. Firstly, this includes the identification of PPARs as the factors that mediated the activation of a target gene by free fatty acids. PPARs were shown to bind to their appurtenant DNA binding sites as a heterodimer with the retinoid X receptor (RXR). While the binding of this complex to DNA was required for PPAR mediated signalling, binding was not sufficient for transcriptional activation implying that the DNA binding site itself acted as an allosteric regulator. Secondly, evidence is presented that identifies two other nuclear receptors that bound to the same DNA binding sites as PPAR. These factors, the chicken ovalbumin upstream promoter-transcription factor 1 and the hepatocyte nuclear factor 4, modulated the activity of PPARα resulting in the abrogation and potentiation, respectively, of PPARα activity. Once bound to specific DNA sequences, transcriptional activators mediate their effects through a network of protein-protein interactions that ultimately controls the transcriptional process. Included in this thesis are studies that established that PPARα interacts with its DNA binding partner RXRα in vivo in the absence of exogenous agonist and DNA binding. This suggested that PPAR and RXR bound to DNA as a preformed heterodimer. To discover novel interacting partners for PPARα, the yeast two-hybrid screen was utilized. Two novel PPARα-protein interactions were identified. This included the discovery and cloning of a novel nuclear receptor, the liver X receptor that interacted with PPARα. Furthermore, an interaction was documented between PPARα and the receptor interacting protein 140, a putative mediator of the transcriptional activation activity of nuclear receptors. In both cases, the liver X receptor and receptor interacting protein 140, antagonized the transcriptional activation mediated by PPARα. These studies have succeeded in increasing the known repertoire of proteins that modulate and effect the activity of PPARα through protein-protein interactions. The findings presented in this thesis have contributed to the understanding of the network of protein-DNA and protein-protein interactions that both potentiate and antagonize the activity of PPARα. This has helped further our understanding of the mechanism by which fatty acids directly regulate the activity of PPARα and control the expression of target genes to elicit adaptive changes in metabolism.

abstract: Doctor of Philosophy (PhD)


title: "Lactilla tends her fav'rite cow": Domesticated animals and women in eighteenth-century British labouring-class women's poetry

contributor:
Walmsley, Peter
English

abstract: This dissertation examines issues of gender, class and species in the work of five eighteenth-century British labouring-class women poets, Mary Collier (1690-1762), Mary Leapor (1722-1746), Elizabeth Hands (fl. 1789), Ann Cromartie Yearsley (1752-1806) and Janet Little (1759-1813). Using ecocriticism, which posits links between literature and the physical world, and ecological feminist theories, which emphasize the interdependence of women and nature as a feminist issue, the author interrogates the meanings of "nature" in the eighteenth century as they are represented in labouring-class women's poetry and in other relevant eighteenth-century texts such as Le Comte de Buffon's Histoire Naturelle (1749-1804), Mary Astell's Some Reflections on Marriage (1700), Bernard Mandeville's Fable of the Bees (1714) and Thomas Topham's Treatise on Cattle (1787). Fashioning new critical readings of labouring-class women's poetry which focus on nature at the intersection of gender, class and species rather than merely the scene of the narrative or the mirror of the protagonist's mind, the author exposes the ideological functions underlying particular conceptualizations of nature. For eighteenth-century labouring-class women poets, a poignant and potent example is the popular idea of the "natural Genius" as an uneducated "rustic" who composes poetry "spontaneously". Chapter one begins by defining "domestication"--of women in the family, animals, domestic servants and labouring-class women poets--in the context of Mary Leapor's poem "Man the Monarch" (1746). In chapter two, the relationship between a labouring-class woman poet and a mad heifer is read through the ecological feminist concept of "interlocking oppressions". In chapter three, the author explores the changing nature of farm labour as the division-of-labour is naturalized within the quintessential emblem of industry--the beehive. Chapters four and five both focus on the forced artificiality of the domesticated pet as "essential" to the nature of a burgeoning consumer culture. The dissertation ends with a consideration of the relationship between literary criticism and environmental politics in the context of the twentieth-century environmental crisis.

abstract: Doctor of Philosophy (PhD)


title: Effect of Capillary Dimensions on Extrudate Swell of Molten Polymers

contributor:
Vlachopoulos, John
Chemical Engineering

abstract:
The effect of capillary dimensions on the extrudate swell of molten polymers is studied with three branched low-density polyethylenes (LOPE) and a broad distribution polystyrene (PS) samples. The polystyrene and one of the low-density polyethylene samples (DHDY-6873) are tested in detail at three extrusion temperatures ranging from 160°C - 220°C, while the other two low-density polyethylene samples are run at one temperature only.

For all polymers, extrudate swell decreases exponentially with increasing length-to-diameter (L/D) ration of capillaries. For a die-orifice (L/D → 0), extrudate swell increases with entry angle up to 150° and decreases thereafter. At constant reservoir diameter DR, extrudate swell also increases with DR/D ratio up to 18 and then drops.

An empirical decay equation is found to correlate well with the extrudate swell data for low-density polyethylenes. However, there is no direct correlation for polystyrene.

Huang and White's new expression predicting extrudate swell with long capillaries does not correlate reasonably well with the experimental data for polystyrene. However, the model as previously suggested by Graessley gives better approximation. Tanner's new inelastic theory on extrudate swell plays no significant part in the present study. The effect of "frozen-in-stresses" on extrudate swell is found to be small.

Huang and White's new model predicting extrudate swell for an orifice-die correlates well with the polystyrene data at low shear rate region (<30 1/sec), but indicates considerable discrepancy at high shear rate region. At present, there is no reilable predictive theory for extrudate swell at higher shear rates both with short and long capillary dies.

abstract: Master of Engineering (ME)


title: Variability in human tooth formation: A comparison of four groups of close biological affinity

contributor:
Saunders, Shelley R.
Anthropology

subject: Anthropology Anthropology

abstract: A considerable amount of research has been undertaken in the area of variability in the timing of human tooth formation. While many researchers acknowledge environmental influences have an impact on dental eruption , differences in the timing of human tooth formation are usually attributed to genetic factors. This thesis, however, investigates the impact of environmental and behavioural influences on the timing and duration of tooth formation by comparing four groups of close biological affinity. Dental development of the Spitalfields sample (18th-19th century London) was found to be retarded in relation to the Poundbury (Romano British), Belleville (19th century Canadian) and Burlington (modern Canadian) samples. Furthermore, tooth size was significantly smaller for the Spitalfields sample. It is argued that these two factors are indicative of environmental stress in the form of poor nutrition and high pathogen load.

abstract: Doctor of Philosophy (PhD)


title: Characterization of aminoglycoside phosphotransferase APH(3')-IIIa, an enterococcal enzyme conferring resistance to aminoglycoside antibiotics

contributor:
Wright, G.D.
Biochemistry

subject: Biochemistry Biochemistry

abstract: Aminoglycosides antibiotics are a clinically relevant class of antibiotics that continue to find use despite the appearance of organisms resistant to these therapeutic agents. Resistance to aminoglycosides may be manifested through several mechanisms including alteration of the ribosomal target, active efflux of the compounds or chemical modification of the antibiotics. The latter mechanism of resistance can occur through O -adenylation, N -acetylation or O -phosphorylation. An aminoglycoside phosphotransferase, APH(3' )-IIIa modifies a broad range of aminoglycoside antibiotics through ATP dependent phosphorylation of the 3' hydroxyl group rendering these antibiotics inoffensive to the bacterium. In an attempt to gain a more thorough understanding of the molecular mechanisms of this drug modification, studies were initiated to determine its substrate specificity and identify residues required for substrate recognition and enzyme activity. The results reported herein, identify residues which line the ATP binding pocket as well as identify substrate structures required for enzyme/substrate interactions. These mechanistic studies further identify a functional similarity between APH(3' )-IIIa and eukaryotic protein kinases. These data have mapped both enzyme and substrate structures required for aminoglycoside detoxification and form the basis for further rational drug design studies.

abstract: Doctor of Philosophy (PhD)