title: Characterization of the Responses of Human Synovial Fibroblasts In Vitro

contributor:
Richards, Carl D.
Health Sciences

subject:
Medicine and Health Sciences
Medicine and Health Sciences

abstract:
The synovial membrane (SM) is a specialized tissue which lines the joint capsule surrounding the interface between bone and cartilage. The intimal layer of the SM, a 1 to 2 cell thick layer of myeloid and mesenchymally-derived cells, has generally been characterized as the population of cells responsible for the secretion of synovial fluid (SF) and with maintaining structural stability within the capsule of diarthrodial joints.

In pathological states, the SM is transformed into an aggressive tissue inundated by inflammatory cells and their soluble mediators. The intimal layer of the SM and its resident cells, Type A and Type B synoviocytes, undergo an alteration in phenotype during disease, particularly chronic joint inflammation. These synoviocytes expand in number and activity and have been demonstrated to be involved in part with the arthritic lesions associated with inflammatory joint disease. The purpose of this thesis is to illustrate that the human synovial fibroblast (HSF or Type B synoviocyte) is a dynamic cell both responding to and influencing its local environment. More specifically, it is documented that HSF activity is significantly affected by a host of locally produced soluble mediators released during arthritic diseases. In addition, HSF are shown to respond to their environment by possessing the capability to alter the activity of other inflammatory cells which are present in the joint milieu. We also show that the pathological state of the originating SM is significant in determining the response and activity of HSF. That is, HSF-derived from normal SM respond to some stimuli differently than do HSF derived from SM originating from diseased joints.

abstract: Doctor of Philosophy (PhD)


title: Finite Group Actions on Smooth 4-Manifolds with Indefinite Intersection Form

contributor:
Hambleton, I.
Mathematics

subject: Mathematics Mathematics

abstract: In this thesis finite cyclic group actions on S² x S² and its moduli space of anti-self-dual connections will be investigated. In the first step the equivariant version of the Donaldson gluing construction of anti-self-dual connections will be developed. We obtain an equivariant obstruction map which provides an equivariant local model of the anti-self-dual moduli space. Then we investigate the special case when we glue the product connection on a trivial SU(2)-bundle over S² x S² with two concentrated anti-instantons. We can achieve transversality of the obstruction map by an equivariant perturbation of the conformal class. We obtain a 10-dimensional equivariant local model which is diffeomorphic to R⁸ x R X S¹. The action on R⁸ is the direct sum of the isotropy representations. The action on the circle depends on the rotation numbers and the self-dual harmonic form. Moreover, there exists an equivariant perturbation of the conformal class so that there are no reducible anti-self-dual connections over S² x S² besides the trivial product connection. These results can be used to show that under certain assumptions the rotation numbers of the isotropy representations of a finite cyclic, smooth action on S² x S² coincide with those of some linear action.

abstract: Doctor of Philosophy (PhD)


title: On the Use of Hybrid Full-Wave CG-FFT and Spectrally Preconditioned CG-FFT Methods for Analyzing Large Microstrip Antenna Arrays

contributor:
Litva, John
Electrical and Computer Engineering

subject:
Electrical and Computer Engineering
Electrical and Computer Engineering

abstract:
In this thesis, we investigate full-wave hybrid Conjugate Gradient - Fast Fourier Transform (CG-FFT) methods for analyzing microstrip arrays. In particular, we investigate spectral preconditioning with the CG-FFT methods.

First, a general scheme is introduced for implementing CG-FFT using the spatial discretization. In comparison with other schemes, the proposed one yields greater accuracy and has higher efficiency because no finite difference approximations are involved, all the aliasing and truncation errors are eliminated and the size of the zero padded region is kept to a minimum.

A hybrid full-wave CG-FFT method is then developed for analyzing microstrip structures. It combines the proposed CG-FFT scheme and the full-wave complex discrete image technique. With this combination, the spatially discrete scheme is realized which can be used for microstrip structure analysis without losing any full-wave information, while at the same time, measuring only minor computational cost and errors. Therefore the merits of the proposed scheme are extended to microstrip problems straightaway.

To further improve the rate of convergence for the CG-FFT method, a new highly efficient spectrally preconditioned CG-FFT method is introduced. This technique takes full ad vantage of the FFT by constructing the special forms of preconditioners and performing the preconditioning in the frequency domain. It uses no any additional memory and only O(NlogN) additional operations for constructing and storing the preconditioner. At the same time it has superior convergence properties compared with the conventional CG-FFT method and other existing preconditioned methods.

The hybrid CG-FFT algorithm developed in this thesis is easily interfaced to UNIX simulation software, including a draw editor and an automatic mesh generator. Using this software, we carry out numerical analyses of different types of microstrip antenna arrays. The analyses are corroborated by experimental measurements. A number of array parameters and boundary effects are studied. These are of interest to antenna design engineers, which include: (1) effect of the finite size of arrays, (2) effect of array shape, (3) spurious radiation from the array feed structures, (4) current distributions on the elements, (5) input impedance and (6) array radiation patterns. Conclusion and discussion are addressed. The performance capabilities of the hybrid full-wave CC-FFT method are demonstrated by a modeling study of very large microstrip reflectarrays. Proposals are made for an improved design for the large array, based on the results of the simulations.

abstract: Doctor of Philosophy (PhD)


title: Thermal Desorption Analysis of Helium Trapping in Ion-Implanted Beryllium

contributor:
Thompson, D.A.
Engineering Physics

subject:
Engineering Physics
Engineering Physics

abstract:
Trapping of 30 keV ion-implanted helium by the radiation-produced damage in hot isostatic pressed beryllium foils of 99.5 wt% purity has been investigated by a series of ion implantation/thermal desorption experiments. Different experimental regimes were designed to obtain some fundamental insight into the behaviour of helium in beryllium. The helium release was related to the surface morphology changes observed on the desorbed surfaces by scanning eIectron microscopy.

The nature of helium trapping in beryllium has been found to strongly depend on the implantation parameters as well as on the thermal treatment of the implanted samples. Desorption peaks have been analyzed in terms of the dissociation of simple helium-vacancy trapping centres and/or helium release from microbubbles that nucleate and grow during the annealing of the implanted samples.

Linear-ramp annealing following room-temperature 30 keV He⁺ implantation in beryllium to a total fluence in the range of 10²⁰ to 10²¹ /m² has produced two desorption stages above 890 K and below 830 K, respectively. The high temperature desorption peak was analyzed in terms of a first-order dissociation mechanism with an activation energy that depends on the relative occupation of the trapping site. The low temperature peak corresponds to a higher-order helium-vacancy cluster that begins to fill once the deeper trapping site approaches saturation. A third trapping site, with higher dissociation energy, has been inferred from the fact that a sizeable fraction of the implanted helium has not been released after heating up to 75% of the melting temperature.

Some samples have been heated by a stepped anneal regime, for two hours at 573 or 773 K, that allows reconfiguration of the trapped helium before being desorbed. The release spectra and the desorbed surface morphology show that the nature of helium trapping has changed to a more stable form of helium bubbles. A model is proposed to account for the helium bubble nucleation and growth by a migration and coalescence mechanism. Linearly ramped thermal desorption after high temperature implantations at 600 and 773 K reveals the formation of more stable trapping sites. The helium release has been related to the formation of holes on the surface and the desorption was inferred to result from microbubble growth by thermal vacancy assisted mechanism.

Some of the samples have been deliberately corroded to investigate the effect of the surface contamination on the helium release. The desorption curves show the formation of an additional broad desorption peak at temperatures higher than 950 K. This is associated with a relative drop in the population of the primary and secondary desorption peaks and implies that the corroded surface contains additional trapping sites that delay the release of the helium detrapped from the bulk.

abstract: Doctor of Philosophy (PhD)


title: Empowering communities or delinquent congregations? A study of complexity and contradiction in Canadian youth cultures and leisure spaces

contributor:
Knight, Graham
Sociology

subject: Sociology Sociology

abstract: This dissertation is a theoretical and empirical examination of youth culture in Canada. Theoretically, a continuum of youth-related cultural theories was devised, and a framework that integrated critical interactionism, structuralism, and postmodern theory was adopted. Empirically, the need for more qualitative research on youth culture in Canada was identified and subsequently engaged through the presentation of two ethnographic case studies that were undertaken on this topic. The first case was a study of the rave subculture in Toronto--a "middle class" culture of youth renowned for drug-use, an interest in computer-generated music, and attendance at all-night "rave" dance parties. The second case was a study of youth in an urban recreation/drop-in centre in a low-income area in southern Ontario. These groups were chosen because of their similar and distinct positionings in relation to social class, strategies of resistance, a (relatively) postmodern context, and urban social spaces. Key components of the rave study included: (a) findings that "rave" was defined by its wide range of forms and characteristics--a range that existed simultaneously across the subculture (e.g., in various raver sub-communities), across the careers of individual ravers (e.g., a loss of idealism about rave's potential as a resistant culture), and across the "life" of the Canadian rave scene (e.g., the scene's evolution); (b) the development of "five theses on resistance" as a framework for understanding the multiple, often contradictory positionings of raver youth; and (c) the adoption of Best and Luckenbill's (1994) model of organizational sophistication as means to conceptualize the "local and global" culture. The youth centre study included findings that: (a) despite a broader context of "risk" outside the centre, youth maintained an informal culture of nonviolence by creating "tolerance rules" that allowed diverse groups to coexist; (b) the youth-driven informal culture of the centre allowed youth to maintain a sense of power in an organization otherwise dominated (administratively) by adults; (c) experiences within the centre, while generally positive, were varied and extremely gendered, with female youth being marginalized in the informal, male-dominated sport culture; (d) among female youth, there existed simultaneously a resistance to broader gender/class based limitations on sport participation, and a reproduction of informal power structures. The dissertation concluded with a discussion of the demonstrated importance/implications of being attentive to complexity in the study of youth culture in Canada.

abstract: Doctor of Philosophy (PhD)


title: Slope Hydroclimatology and Hydrologic Responses to Global Change in a Small High Arctic Basin

contributor:
Woo, M.K.
Geography

subject: Geography Geography

abstract: This study evaluated the present-day interactions between the atmosphere, soils, water flow and vegetation patterns of a remote area of Northern Canada. This study showed that microclimatic processes (temperature, radiation) are often the driving force behind snowmelt and ground thaw. This study also showed that it was possible to use limited field camp data (e.g. 2x daily cloud, temperature, wind) to simulate radiation and energy fluxes for a variety of surfaces. This suggests the model's utility by cologists and earth scientists working in other areas of the Arctic. This thesis also showed that it was possible to use point data to simulate melt and evaporation for a small High Arctic basin and to investigate some possible implications of climate change to water movement. This last stage of the study will be particularly relevant to climatologists, ecologists and geomorphologists working in the north.

abstract: Doctor of Philosophy (PhD)


title: Orientalist Typologies: The Cultural Politics of the Female Subject in Maxine Hong Kingston's The Woman Warrior and Joy Kogawa's Obasan

contributor:
Goellnicht, Donald C.
English

subject:
English Language and Literature
English Language and Literature

abstract: This thesis examines the persistence of psycholinguistic orientalist typologies in Maxine Hong Kingston's The Woman Warrior (1976), Joy Kogawa's Obasan (1981), and in selected criticism of the two works. The discussion of Orientalism uses Edward Said's Orientalism (1978) uses Edward Said's Orientalism (1978) as a point of reference but the specific operation of a psycholinguistic Orientalism is derived from the critique of Julia Kristeva's About Chinese Women (1977) by Gayatri Chakravorty Spivak, Rey Chow and Lisa Lowe. The Orientalist typology in The Woman Warrior and Obasan is organized around the mother-daughter relationships that are central in both works. The thesis reveals how these works have attracted a number of psychoanalytic readings that employ Kristeva's theory of poetic language but that are unaware of her Orientalist application of this theory in About Chinese Women. Orientalist typologies re-emerge in readings of The Woman Warrior and Obasan that use or allude to Kristeva's psycholinguistic theory but they are also embedded in the texts as well. Unlike the approach of earlier Asian American male critics such as Frank Chin, this thesis argues that the Orientalist aspects of The Woman Warrior and Obasan do not implicate the texts as necessarily flawed or incorrect. A generous understanding that texts by writers of East Asian ancestry can be Orientalist and that this operation can occur at the psychoanalytic level of the formation of the linguistic subject allows the writer's alienation from her culture of ancestry to function as an affirmative and crucial element in her story-making.

abstract: Doctor of Philosophy (PhD)


title: Demography and breeding behaviour of brown-headed cowbirds: An examination of host use, individual mating patterns and reproductive success using microsatellite DNA markers

contributor:
Gibbs, H. L.
Biology

subject: Biology Biology

abstract: I analyzed six years of data collected from a marked population of a brood parasitic bird, the Brown-headed Cowbird (Molothrus ater ) at Delta Marsh, Manitoba. I used mark-recapture techniques and observation to document annual survival probabilities and population sex structure. I used genetic markers to describe host use patterns, individual mating patterns and reproductive success. In general, males had higher survival than females and the sex ratio of the population was 1.9 males per female. Analysis of the community-level patterns of host use indicated that host choice was nonrandom. The probability of parasitism on different host species may have been influenced by the relative availability of the nests of each host species, the degree of host nesting synchrony and the quality of the host species. Analysis of individual host use behaviour showed that most females used more than one host species, but there was evidence of nonrandom host use by some individuals in this population. The mating system was variable across years, but in general, more females than males were likely to have a single mate within a breeding season but neither sex was strictly genetically monogamous. The reproductive success of both males and females increased as individuals gained additional mates. In general, the host use and mating behaviours of individual cowbirds varied across years. This flexibility may allow individuals to adapt to annual and geographical variation in the environment.

abstract: Doctor of Philosophy (PhD)


title: Membrane Assembly and Translation Pausing of the Signal Recognition Particle Receptor α Subunit

contributor:
Andrews, David W.
Biochemistry

subject: Biochemistry Biochemistry

abstract: The α subunit of the signal recognition particle receptor (SRα) is targeted to the endoplasmic reticulum membrane by a mechanism independent of the signal recognition particle-mediated translocation pathway. The membrane binding of SRα polypeptides was examined using a cell-free translation and targeting system. A membrane binding domain consisting of the amino-terminal 140 residues of SRα was identified. This domain forms a protease-resistant folded unit, and is the major site of tight binding to the β subunit of the receptor (SRβ). SRα was also shown to be a peripheral membrane protein, suggesting that it is bound to the membrane largely via interactions with the integral membrane SRβ. Co-translational targeting of SRα was correlated with a translation pause site on the SRα mRNA. An mRNA sequence at this pause site that resembles a class of retroviral frameshift sites was shown to be necessary and sufficient for a strong translation pause. SRα polypeptides synthesized from a mutant non-pausing mRNA were impaired in co-translational membrane binding, and translation-dependent localization of polysomes synthesizing SRα. These data resolve a discrepancy in earlier reports concerning the membrane attachment of SRα. Moreover, a novel pathway for polypeptide targeting and mRNA localization is proposed, and a previously undescribed signal for translation pausing is identified. Translation pausing may be general mechanism to coordinate co-translational folding, oligomeric assembly and targeting of other proteins.

abstract: Doctor of Philosophy (PhD)


title: Modeling of existing and rehabilitated reinforced concrete buildings

contributor:
Ghobarah, A.
Civil Engineering

subject:
Civil Engineering
Civil Engineering

abstract: There are many existing buildings which have been designed according to earlier codes. In these codes, either design for seismic loads was not a requirement or design was for lower levels of seismic forces. One of the major challenges that faces structural engineers is to determine the seismic capacity of an existing building and to rehabilitate these buildings to upgrade their seismic capacity if needed. At present, there are no guidelines available for the rehabilitation of existing structures and for the design of different retrofitting techniques. One of the most effective ways of rehabilitation is the addition of reinforced concrete (RC) walls. Until now, there is no robust analytical model available to study the effect of adding RC walls on the building behaviour up to failure. To determine the building seismic capacity and to study the effect of adding RC walls, the analytical model used should be capable of representing all the deficiencies in existing buildings. Moreover, it should be able to represent all possible failure modes such as beam-column joint shear failure, cumulative concrete crushing and bond slip failure. The objective of the present research is to evaluate the behaviour of buildings retrofitted by the addition of reinforced concrete structural walls. This was done by the development of a suitable analytical model that fully describes the behaviour of existing buildings before and after rehabilitation using RC structural walls. This model was verified using test results on specimens representing existing structures and found to give results that are closely correlated to the experimental results. The model was able to detect the failure mechanisms observed in the experiments. This model was used in the analysis of an existing three-storey building to determine its seismic capacity. The effect of ignoring the beam-column joint shear deformations, bond slip and concrete crushing was studied. Ignoring any of these parameters can change the building failure mechanism which could lead to misleading results. After that, a suitable rehabilitation technique using RC walls was chosen and the building behaviour after rehabilitation was studied.

abstract: Doctor of Philosophy (PhD)


title: Regime Analysis and International Organizations: Unctad and International Shipping

contributor:
Pentland, Charles C.
Political Science

subject:
Political Science
Political Science

abstract:
This thesis examines the role of international organizations in the shipping industry, and specifically the role of UNCTAD's committee on shipping. By using the concept of regime analysis the thesis aims to establish how international agencies have reflected and challenged the structures and principles of the industry relative to other factors either specific to the sector or of a broader economic or political origin.

Regime analysis is an outcome of the debate within international theory about the relevant focus for the study of international relations and the significance of international institutions. It seeks to establish the structure and dynamics of particular areas of the international system, or international political economy, and looks at the roles of states, and other actors, whether they be non governmental or international, in shaping the regime. It also examines the principles and norms which govern a regime and how these manifest themselves in practice. Within this context it becomes possible to assess how far international organizations are autonomous actors within that regime and how far they merely reflect its structure and principles.

Using this analysis the thesis proceeds to examine the structures and principles of the international shipping regime. It surveys the progress of the regime from statism to a self-regulation and back again and looks at the factors behind these changes. It then looks at the role of international ,organizations in that regime and especially of UNCTAD. The development of the Shipping Committee is dealt with in the fourth chapter as is the evolution of the Code of Conduct for Liner Conferences. The conclusion assesses the significance of UNCTAD within international shipping and at the relevance of the case for regime analysis and theories of international relations.

abstract: Master of Arts (MA)


title: Multibeam smart antenna systems for wireless communications

abstract: Smart antennas have emerged as one of the key technologies in wireless communications. This thesis focuses on developing algorithms and structures that can be applied to one of the most important types of smart antennas--the multibeam smart antenna--in order to improve the quality and capacity of both existing and future wireless networks. A large database, consisting of vector channel measurement data using an 8-element circular antenna array is analyzed to investigate the underlying characteristics of the multibeam smart antenna in practical propagation environments. Extensive vector channel simulations are also conducted, including the innovative work on the simulation of smart antennas in Frequency Division Duplexing (FDD) systems. Based on the data analysis and simulation results, two multibeam smart antenna algorithms, one for reception and one for transmission, are proposed. Significant performance and capacity improvements can be achieved using these two algorithms. The proposed multibeam smart antenna reception algorithm for DS-CDMA system is expected to have important application in both existing and the third generation CDMA systems, while the proposed multibeam smart antenna transmission algorithm can be used in FDD wireless networks to solve the downlink problem.

abstract: Doctor of Philosophy (PhD)


title: Hadron masses and the non-relativistic quark model

contributor:
Nogami, Y.
Physics

subject: Physics Physics

abstract:
The hadron masses are calculated in the non-relativistic quark model by solving the Schrödinger equation with a suitable potential. The three-body baryon problem is solved by the Feshbach-Rubinow method.

The Fermi-Breit potential proposed by De Rújula, Glashow and Georgi is shown to be unsuitable for non-relativistic hadron systems. Some phenomenological potentials are then examined by which light hadron masses may be fitted and remain only marginally relativistic. Moreover, such interactions indicate the necessity for long-range spin dependence and permit the validity of a perturbative approach to be tested.

An attempt is made to consistently fit charmonium together with lighter hadrons by using a logarithmic potential and incorporating a perturbative type estimate of the relativistic kinetic energy. It is found that while the vector meson masses are well reproduced the baryonic masses are somewhat overestimated.

abstract: Master of Science (MS)


title: The Dynamics of Lactate and Ammonia In Rainbow Trout (Oncorhynchus mykiss) White Muscle

contributor:
Wood, Chris M.
Biology

subject: Biology Biology

abstract:
Fish engage in intensive exercise, both naturally or through human intervention, resulting in an extensive series of physiological and biochemical disturbances. The first part of the study assessed a range of different sampling, processing, and analytical methods for determining selected metabolites in trout muscle. The goal was to provide a set of reliable methods to preserve the original metabolic state in muscle. The second part of this study employed these methods and used rainbow trout (Oncorhynchus mykiss) as an in vivo model to examine the integrated responses of white muscle and plasma (acid-base, electrolytes, fluid volume, and metabolic state) to severe exercise. The investigation also addressed the issues of transmembrane distribution and transport of lactate, metabolic protons, and ammonia. In the third and largest section, an isolated-perfusion tail-trunk preparation (in vitro) was developed to characterize mechanisms involved in the regulation of lactate, ammonia, CO₂, HCO₃ˉ, and proton movement across the muscle cell membrane in both resting and post-exercise muscle.

Together, these studies yielded an integrated picture of the responses to intensive activity in trout white muscle. Exhaustive exercise induced a massive depletion of muscle glycogen, the majority of which was converted to lactate. The retention of lactate, and good carbohydrate conservation, suggested that, in situ glycogenesis, not oxidation, was the major fate of lactate in exercised muscle. The post-exercise redox state of muscle remained oxidative, challenging the traditional concept of "anaerobic" lactate production. The unorthodox involvement of fatty acid oxidation in exercised muscle was indicated by the elevated acyl-carnitine and decreased free carnitine levels. Small amounts of lactate and metabolic acid (ΔHm⁺) were released slowly from exercised muscle into extracellular fluid, and the two fluxes were uncoupled. H⁺ flux reacted to both pH and electrochemical gradients. Lactate distribution did not reach its electrochemical equilibrium, and changes in lactate efflux were more sensitive to the lactic anion (Lac) concentration gradient than to the lactic acid (HLac) gradient, suggesting the possible involvement of electro-neutral carrier-mediated lactate transport. For the first time, it was clearly demonstrated, via the application of the specific inhibitors, α-cyano-4-hydroxycinnamate (CIN) and 4-acetamido-4'-isothiocyanos-tilbene-2,2'-disulphonate (SITS) in conjunction with L- and D-Iactate kinetics, that the carrier-mediated lactate transporters (Lacˉ/H⁺ symport and Lacˉ/HCO₃-Cl antiport), and free diffusion of HLac were involved in the transmembrane lactate exchange in both the resting and exercised fish white muscle (in vitro). The "lactate retention" theory was supported by this study.

The decrease of ATP in the post-exercise muscle was mirrored by the increase in total ammonia (Tᴀᴍᴍ = NH₃ + NH₄⁺) and IMP. This suggested that adenylate deamination was the souce of ammonia production, and that the retention of ammonia in muscle was used for adenylate resynthesis. Muscle membranes were permeable not only to NH₃, but also to NH₄⁺, and the Tᴀᴍᴍ distribution was affected by both pH and electrical gradients. Membrane potential may be more important in determining ammonia distribution (NH₄⁺ permeable) during the post-exercise condition whereas the pH gradient may be more important (NH₃ permeable) at rest. The lack of change in ammonia flux in response to amiloride treatment revealed that the NH₄⁺/Na⁺ exchanger was not involved in ammonia efflux.

abstract: Doctor of Philosophy (PhD)


title: Canadian "Chivalry" in Vietnam: The Press Coverage

contributor:
Knight, G.
Sociology

subject: Sociology Sociology

abstract:
This research examined newspaper coverage of Canada's political, economic, and social involvement in the war in Vietnam from 1954 to 1973. The research questioned whether the reporting followed the claims of the propaganda or the ideological process model. Were the news reports a form of propaganda with the media acting as instruments of the dominant elite by reproducing the views and opinions of prominent political officials? Or did the news coverage include debate, variety, and revision--characterizing the contestation of an ideological process as predicted by hegemony theory?

Both content and semiotic structural analysis were used to examine the press reports. Content analysis was used to provide a detailed summary of the overt characteristics of the data. Semiotic structural analysis examined changes in thematic content as well as the construction and maintenance of a preferred perspective.

The findings indicate that news coverage of Canadian participation in Vietnam closely mirrored dominant political views, as predicted by the propaganda model. The media reproduced a narrow, limited version of events when politicians maintained a conservative, Cold War consensus. But during such periods when political debate was characterized by an ideological openness, news coverage directly mirrored a wider variety of themes and sources in a more open format.

Furthermore, newspaper coverage of Canada's involvement in the war in Vietnam favored a 'chivalry metaphor'. News reports tended to reflect the idealistic romanticism of this metaphor. In contradiction to other, more realistic perspectives on events, notions of charity and honour were firmly established in early news articles. This viewpoint persisted throughout the war and was only reviewed when the Pentagon Papers provided an alternative and authoritative source of information. Then Canada was portrayed as a submissive errand boy rather than a gallant knight.

In summary, the propaganda model partially accounted for the characteristics of the data. The news articles examined were usually reproductions of state policy. Government perceptions of events did overwhelmingly determine the perspective favored in the news reports. Yet, there was a marginal voice of criticism and debate that gained some prominence as the Vietnam War ended. Nevertheless, Canadian newspapers were generally faithful servants of the state.

abstract: Doctor of Philosophy (PhD)


title: Fibroblast Heterogeneity and Pulmonary Fibrosis

contributor:
Gauldie, Jack
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
Idiopathic pulmonary fibrosis is a chronic inflammatory disease of the lung characterized by pathologic alterations with fibroblast proliferation and disordered deposition of extracellular matrix resulting in impairment of gas exchange often leading to respiratory failure. In the pulmonary interstitium, the fibroblast and the extracellular matrix products they produce, play a pivotal role in maintaining the structural and functional integrity of the lung.

In the study of lung fibrosis and other fibrosing diseases much attention has been directed at events which alter fibroblast activities. In this construct however, the lung fibroblast is viewed merely as a homogeneous target cell altering its behaviour as a result of immune and inflammatory events. Importantly, it has become apparent over the years that (1) fibroblasts are themselves effector cells capable of releasing a variety of growth factors and mediators and (2) that fibroblasts comprise a heterogeneous population, both within and between tissues. Therefore, an alternative, but not a mutually exclusive hypothesis considers the heterogeneous nature of the fibroblast population and the potential contribution of various subpopulations to disease expression.

Our first report that fibroblasts derived from chronically activated and inflamed human lung tissue behaved differently than normal fibroblasts suggested that fibroblast populations present in fibrotic lung tissue exhibited accelerated growth rates. In order to further examine the growth characteristics of fibrotic lung fibroblasts, a soft agarose culture system was established in which we examined the ability of lung fibroblast primary lines to form colonies under anchorage-independent growth conditions, possibly equating to aggressive or "transformed" behaviour. Fibroblasts derived from the Iungs of patients with idiopathic pulmonary fibrosis exhibited anchorage-independent growth in soft agarose culture whereas fibroblast lines derived from normal adult tissue did not. These colonies were fibroblast-like according to morphology and immunohistochemical stain characteristics, and the ability to grow under semi-solid growth conditions was maintained by the fibrotic derived cells even after selection and expansion of single colonies. Interestingly, fibroblast cell lines derived from neonatal lung tissue also exhibited the ability to grow as colonies under soft agarose growth conditions suggesting newly differentiated fibroblast populations may be prevalent in fibrotic lung tissue.

The effect of various growth and differentiating factors on the modulation of the anchorage-independent colony formation phenotype was examined in vitro. Treatment with various growth factors, including PDGF, FGF, EGF, TGFβ and corticosteroid were able to modify the colony forming abilities of fibrotic and neonatal fibroblast lines. Importantly, none of the above treatments was able to induce fibroblasts derived from normal adult lung tissue to form colonies. The ability of IPF fibroblast lines and neonatal lung fibroblast lines to form colonies under soft agarose growth conditions was inhibited by treatment with retinoids, known differentiating agents, implying the modulation/differentiation of a particular fibroblast phenotype toward a more mature phenotype; one incapable of anchorage-independent growth.

Since the ability to form colonies under soft agarose growth conditions by fibrotic fibroblasts appeared to be a stable and disease specific phenotype and since in vitro we were able to successfully modulate this behaviour with retinoids, we examined the effect of orally administered retinoic acid on the modulation of the fibrotic lung response in a rat model of bleomycin induced pulmonary fibrosis. In this study, we report that the in vivo administration of all-trans retinoic acid significantly decreased the number of fibrotic lesions and dramatically altered the pattern of collagen deposition in the bleomycin treated lung.

These studies have confirmed and extended our earlier hypothesis concerning the contribution of fibroblast heterogeneity to the pathogenesis of pulmonary fibrosis and suggests avenues of intervention that may lead to alteration of the fibrotic tissue and return to normal lung function.

abstract: Doctor of Philosophy (PhD)


title: Studies in Data Reconciliation Using Principal Component Analysis

contributor:
Crowe, Cameron M.
Chemical Engineering

subject:
Chemical Engineering
Chemical Engineering

abstract:
Measurements such as flow rates from a chemical process are inherently inaccurate. They are contaminated by random errors and possibly gross errors such as process disturbances, leaks, departure from steady state, and biased instrumentation. These measurements violate conservation laws and other process constraints. The goal of data reconciliation is to resolve the contradictions between the measurements and their constraints, and to process contaminated data into consistent information. Data reconciliation aims at estimating the true values of measured variables, detecting gross errors, and solving for unmeasured variables.

This thesis presents a modification of a model of bilinear data reconciliation which is capable of handling any measurement covariance structure, followed by a construction of principal component tests which are sharper in detecting and have a substantially greater power in correctly identifying gross errors than the currently used statistical tests in data reconciliation. Sequential Analysis is combined with Principal Component Analysis to provide a procedure for detecting persistent gross errors.

The concept of zero accumulation is used to determine the applicability of the established linear/bilinear data reconciliation model and algorithms. A two stage algorithm is presented to detect zero accumulation in the presence of gross errors.

An interesting finding is that the univariate and the maximum power tests can be quite poor in detecting gross errors and can lead to confounding in their identification.

abstract: Doctor of Philosophy (PhD)


title: Carrier Escape from Semiconductor Quantum Wells

contributor:
Preston, John S.
Physics

subject: Physics Physics

abstract:
The escape of photogenerated carriers from semiconductor quantum wells is investigated theoretically and experimentally. Calculations of the tunnelling, thermionic emission, and thermally-assisted tunnelling escape times are given, where the thermionic emission process is split into low and high field regimes. At low fields, the escape rate is limited by the diffusion of the continuum carriers away from the well, while at high fields, the scattering rate from the confined to continuum states is the limiting process.

Barrier lowering effects are reviewed. The image force barrier lowering in a quantum well is calculated in the classical quasi-static approximation where the diffusion current is included for the first time. Both bipolar and unipolar wells are considered. In each case, the diffusion current inhibits the image charge formation, resulting in significant reductions in the barrier lowering; this is quantified by the concept of the effective image charge. At high carrier densities in the well (≥10¹² cmˉ²), it has a value approaching the electronic charge, while at low densities (≤10¹⁰ cmˉ²), it tends to zero. The only exception is in the case of majority carrier escape from a unipolar well, where at sufficiently high fields the barrier lowering is independent of the electric field.

Calculations of the 2D-to-3D scattering rate required for the high field description of thermionic emission are presented where the effects of a transverse electric field are explicitly included. Deformation potential and piezoelectric scattering by acoustic phonons are considered for the first time, as well as polar scattering by longitudinal optical (LO) phonons. It is found that polar LO phonon absorption dominates the thermionic emission rate at all temperatures despite its infinitesimal occupation factor at low temperatures. This is attributed to lowering of the effective barrier by an amount equal to the phonon energy. As the electric field is increased, the scattering function is smeared such that the rate is reduced just above the barrier, while a low energy tail extends to energies below the barrier. The scattering function does not shift with the potential barrier as expected, nor does the scattering rate rise abruptly at the barrier energy. As a result, it is expected that image charge lowering of the barrier will have only a minor effect on thermionic emission rates, particularly at higher temperatures. Calculations are presented for a range of well widths and depths. It is found that the emission rate oscillates as a function of the well width, with the jumps in emission rate corresponding to the confinement of a new upper subband.

Fits to the calculated scattering functions are presented as the basis for a simplified thermionic emission calculation. The step function approximation gives a simple analytic formula but performs well only in limited cases. A more complex approach, where the scattering function is approximated as a Fermi-Dirac function, reproduces the results of the full calculation to within 10% in most situations.

Calculated electron escape times are compared with reported experimental values from an asymmetric GaAs/AIGaAs quantum well (Cavaillès, 1992) with qualitative success. While the bias dependence was well reproduced, the calculated thermionic emission times were slow by factors of ~3-5. The principal causes of this discrepancy are believed to be band non-parabolicities and inaccuracies in the 3D density of states.

Measurements of hole escape times in an InGaAsP/InP multiple quantum well laser structure using time-resolved photoconductivity (PC) are presented as a function of temperature and bias. These are compared with calculated values which reproduce the qualitative behaviour but underestimate the thermionic emission time by one to two orders of magnitude. This is attributed primarily to the complexity of the valence and structure, further illustrating its impact on thermionic emission calculations.

abstract: Doctor of Philosophy (PhD)


title: The Middle Iroquoian Colonization of Huronia

contributor:
Ramsden, Peter
Anthropology

subject: Anthropology Anthropology

abstract: This archaeological study focuses on the identification and analysis of prehistoric Iroquoian migration patterns, and the examination of the adaptations made by pioneering Middle Iroquoian horticulturalists who colonized Simcoe County in south-central Ontario in the early fourteenth century. Unlike some other areas of southern Ontario where there is clear evidence of in situ development from the Early Iroquoian through to the Late lroquoian period, the earliest Iroquoian village sites in Simcoe County date to the Middle Iroquoian period. In order to confirm that the Middle Iroquoian occupation was the result of a migration, an archaeological migration model formulated by David Anthony (1990) was adopted in this study. The Anthony (1990) model contends that migration is a structured process that develops in a predictable manner once it has begun. Several of the general migration patterns identified by Anthony, as well as several new aspects of Iroquoian migrations, were identified in this study. The results of this study indicate that Iroquoian migrations do evolve in a predictable manner and exhibit several characteristics which are readily identifiable using archaeological data. This includes familiarity with the destination area prior to the actual migration, a leapfrog settlement pattern consisting of settlement clusters, the placement of initial settlement clusters in areas which are easily accessible from the source area, an initial settlement system which has already been introduced in its final format with the placement of semi-sedentary village sites in strategic locations within resource rich areas, and rapid initial population growth rates in the newly colonized area. While any archaeological migration process will vary to some extent depending on the physical environment, socio-political organization, technological sophistication and settlement-subsistence patterns of the group involved, the migration patterns identified here are applicable to other suspected migrations involving slash and burn horticulturalists.

abstract: Doctor of Philosophy (PhD)


title: A Mass Spectrometric Study of Low Energy Rearrangement Reactions in Oxygen Containing Ions

contributor:
Terlouw, J.K.
Chemistry

subject: Chemistry Chemistry

abstract:
Low energy rearrangement reactions in selected oxygen-containing ions have been studied by means of mass spectrometry-based techniques (metastable ion (MI), collision-induced dissociation (CID), neutralization-reionization (NR) mass spectrometry as well as multiple collision experiments (MSⁿ)) in conjuntion with ab initio molecular orbital calculations.

The atom connectivity in the product ions has been investigated in detail by tandem mass spectrometry-based experiments on ²H-, ¹³C- and ¹⁸O-labelled isotopologues of some oxygen-containing ions. The thermochemical data (i.e. heat of formation (ΔHf) values) of the oxygen-containing ions have been obtained either experimentally from the appropriate measurement of ionization energy (IE), appearance energy (AE) and/or proton affinity (PA) or computationally.

It has been proposed that the C-H∙∙O bonded counterparts of the O∙∙H∙∙O bonded species may, despite their lower thermodynamic stability, play an even more important role in the decay of oxygen-containing radical cations of the type HOCH(R₁)C(=O)R₂˙⁺. A case in point is ionized acetol (R₁=H,R₂=CH₃), methyl glycolate (R₁=H,R₂=OCH₃), methyl lactate (R₁=CH₃,R₂=OCH₃) and acetoin (R₁=R₂=CH₃). These species all dissociate by loss of R₁CO˙ by double hydrogen transfer (DHT). It is further proposed. from ab initio calculations, that the C-H∙∙O bonded intermediate R₁C(H)=O⋯H-C(=O)R₂˙⁺, I, does not lose R₁CO˙ via a hydrogen atom shift from neutral R₁C(H)=O to ionized H-C(=O)R₂˙⁺.

Instead, charge transfer takes place in I so that the neutral R₁C(H)=O becomes charged and thus it can rotate and donate a proton to H-C(=O)R₂, after which dissociation follows.

Keto-enol tautomerism in the dilute gas-phase has been studied in the unimolecular reactions of ionized ethyl glycolate, HOCH₂CO₂C₂H₅˙⁺, II, and its enol isomer, HOCH=C(OH)OC₂H₅˙⁺, III. It has been shown that the metastable ionized keto isomer II undergoes unidirectional isomerization to the enol ion III, via two consecutive 1,5-hydrogen shifts, from which C₂H₄ is lost to give the ionized trihydroxyethylene, (HO)₂C=CH(OH)˙⁺. NR experiments show that neutral trihydroxyethylene in the gas-phase is a remarkably stable species, which does not tautomerize to the keto isomer glycolic acid, HOCH₂CO₂H.

Some members of the important homologous series of oxonium ions, CnH₂n₊₁O⁺, have been extensively investigated by ²H- and ¹³C-labelling experiments especially at low internal energies. Their intriguing unimolecular chemistry has been interpreted by means of mechanisms in which distonic ions and ion/neutral complexes play crucial roles in the hydrogen transfer and skeletal isomerization steps.

Finally, part of the C₃H₅O₂+ potential energy surface was investigated by ab initio molecular orbital calculations and by mass spectrometry-based experiments to ascertain whether the carbonyl-protonated β-propiolactone ions CH₂CH₂OCOH⁺, IV, can interconvert in the dilute gas-phase with protonated acrylic acid, CH₂=CHC(OH)₂⁺, V, as suggested in a thermolysis study. It is shown that metastable ions IV do not communicate with ions V and the observed equilibrium IV ⇆ V in solution is due to an intermolecular process. Also, ions IV do not undergo cycloreversions to HOCO⁺ + C₂H₄ and to CH₂=COH⁺ + CH₂O, but rather they spontaneously dissociate CH₃CHOH⁺ + CO, CH₃CO⁺ + CH₂O, CH₂=CHCO⁺ + H₂O and C₂H₅⁺ + CO₂. The product ions of these dissociation reactions are characterized by multiple collision experiments and mechanisms for their formation are proposed. Analysis of appropriate isodesmic reactions indicate that the α-COOH group in 1-carboxyethylium ions, CH₃CHCOOH⁺, behaves as a hydrogen atom and therefore this group cannot be said to destabilize the adjacent positive charge.

abstract: Doctor of Philosophy (PhD)


title: Synthesis of novel organofunctional silicones and silanes for interface control

contributor:
Brook, Michael A.
Chemistry

subject: Chemistry Chemistry

abstract: The synthesis and characterization of new organo-functional silicones bearing nitrilotriacetic acid chelating moieties is described. Several synthetic pathways were explored towards this goal and the most promising synthesis was used in order to obtain five different chelating silicones. These compounds formed insoluble films on aqueous surfaces. An investigation of the surface pressure exerted by these films was performed by employing a Langmuir trough. For comparison, a series of five new carboxylic acid-functional silicones was also synthesized and studied. The effect of molecular weight, type and position of functional group, and metal cation presence in the subphase are discussed. Possible conformations adopted by these polysiloxane derivative polymers at the surface were also presented. The design, synthesis, and characterization of small molecular weight organosilane linkers that can control hydrophobic - hydrophilic interfaces in wood - polyolefin composites by means of covalent bond formation is described. Several vinylallylsilane-based coupling agents were synthesized and their radical-initiated grafting onto polyethylene and squalane (a polyolefin mimic) was presented. One such organosilane, dimethyl(γ-hydroxypropyl)-vinylsilane, combined with a low molecular weight polyethylene-g -maleic anhydride oligomer, was used in order to reinforce wood - polyethylene composites and the mechanical properties of these materials were described.

abstract: Doctor of Philosophy (PhD)


title: Exogenous targeting instruments for eliciting efficiency in groups

contributor:
Muller, Andrew R.
Kuhn, Peter J.
Mestelman, Stuart
Economics / Economic Policy

subject: Economics Economics

abstract: When an individual agent's actions are unobservable, there is often an incentive for that agent to act in a way which is not socially optimal. This is the crux of the moral hazard problem and is compounded when there are a group of agents. Moral hazard in groups is a common social dilemma which encompasses situations such as the worker effort problem, contributions to public goods, and the abatement of non-point source pollution. Holmstrom (1982) suggests what is referred to as a forcing contract to induce a group to choose the optimal or target outcome. However, the optimal outcome is only one of many possible Nash equilibria under these forcing contracts. Segerson (1988) suggests the use of exogenous targeting instruments which do implement the optimal outcome as a unique Nash equilibrium. The purpose of this thesis is to test these different instruments in a controlled laboratory environment to determine whether they are able to induce a group of agents to select the socially optimal outcome. There are many studies which conclude that the target outcome cannot be attained under the Holmstrom (1982) forcing contract. Most notable among these studies is the 1997 paper by Nalbantian and Schotter. They conclude that costly monitoring or competitive teams are required to mitigate the problem of moral hazard in groups in an experiment based on the worker effort problem. The results from the experiment discussed in this dissertation show that some exogenous targeting instruments can induce groups of both homogenous and heterogeneous individuals to choose a target outcome. However, significant differences from Nash behaviour are observed at the individual level. It is shown that these differences can be explained by preferences for equity and decision error.

abstract: Doctor of Philosophy (PhD)


title: Analysis of the Variation of the Oxygen Isotopic Composition of Mammalian Bone Phosphate

contributor:
Schwarcz, H.P.
Geology

subject: Geology Geology

abstract:
For the oxygen isotopic composition of bone and other biogenic phosphates to be a useful palaecclimatic tool it is necessary to process large numbers of samples precisely and rapidly. This study describes the development of robust and rapid analytical methods to achieve this and demonstrates their use in two practical studies.

Silver orthophosphate was chosen as the most suitable compound for oxygen isotopic analysis of phosphates due to its defined stoichiometry and lack of structural or adsorbed water. Biogenic phosphates are processed to silver phosphate by dissolution in acetic acid, followed by removal of the calcium as calcium oxalate and sequestering of the phosphate as lead phosphate. Organic material is then oxidized by heating with concentrated nitric acid and hydrogen peroxide before lead phosphate is reprecipitated and the lead removed as lead sulphate, leaving the phosphate in solution. The phosphate is precipitated as coarse crystals of silver orthophosphate by evaporation of an ammoniacal silver nitrate solution.

Oxygen is liberated from the silver orthophosphate by polymerization and reaction with bromine gas at 550°C in a vacuum line. Bromine is a catalyst and a reactant in the process; electrons are transferred from the oxygen to the bromine to catalyze the reaction and the silver is stabilised as silver bromide to prevent back-reaction. The isotopic composition of the gaseous oxygen is determined only by the temperature of the reaction and the isotopic composition of the silver orthophosphate. The product polymer consists of three to four phosphate ions, so that the reaction yields rather less than one oxygen atom from each phosphate ion or about 17% of the total oxygen.

Sixteen beaver (Castor canadensis) were obtained from October through May in southern Ontario. Enamel was ground from their continuously growing incisors, and a smaIl sample of bone was removed from each of their mandibles. The phosphate was analyzed using the methods described above. The results showed a seasonal variation in the δ¹⁸O of their incisor enamel of approximately 4‰. The δ¹⁸O of the beaver's body water decreases gradually through the winter and spring, rising rapidly in the summer. Seasonal fluctuation was not reflected in the δ¹⁸O of the adult beaver bone which was almost constant over the whole area. A Sangamonian giant beaver (Castoroides ohioensis) incisor obtained from Hopwood Farm, Illinois gave a climatic response curve similar to the Castor samples but the tooth grew more slowly and recorded 1.3 years of growth, with seasonal fluctuation in δ¹⁸O of 5‰ and a mean value about 5‰ heavier than in the modern beaver studied, reflecting a warmer climate with significant annual temperature fluctuation.

The city of Teotihuacan, near modern Mexico City, expanded in size rapidly from 100 BC to 200 AD due to substantial immigration from areas including the Gulf and Pacific seaboards where the δ¹⁸O of rain is substantially different from rain at Teotihuacan. Individuals who died before their bones could completely remodel should preserve this different signature in the δ¹⁸O of their bones. Samples (mostly ribs) from sixty-four individuals were analyzed, representing the major ethnic barrios in the city, the mass sacrifices associated with the foundation of the Temple of Quetzalcoatl and inhabitants of the Valley of Oaxaca: the supposed homeland of some of the immigrants. The δ¹⁸O of the bones had apparently not altered, despite diagenetic effects which were identified by infrared spectra, x-ray diffraction and elemental analyses. Distinct differences in δ¹⁸O were found between different groups in the city but these were not clearly related to their ethnic origins. The samples from the hotter and lower Valley of Oaxaca were analyzed and found to have lower δ¹⁸O than the inhabitants of Teotihuacan, the opposite of the expected relationship. This reversal was ascribed to Oaxaca being in lite rain shadow of the mountains.

abstract: Doctor of Philosophy (PhD)


title: Building and being built: Constructing Jewish identities on an Israel experience program

contributor:
Badone, Ellen E.F.
Religious Studies

subject: Religion Religion

abstract: Livnot U'Lehibanot (To Build and to be Built), a three-month work-study program in Israel for North American Jews in their twenties. This study will focus on the Jewish message and methods of Livnot U'Lehibanot , in order to explore the impact and significance of the program for participants' Jewish identities. Similar programs offering youth travel to Israel are extremely popular within the organized Jewish community, and are perceived to promote Jewish identification and cultural continuity. Using categories of Israel, Jews and Judaism, I analyze Livnot 's message, presentation and goals in order to examine more closely the Jewish worldviews that participants learn about and in which they take part during the program. With attention to recent anthropological and post-colonial theory on the dynamics of cultural hybridity and ambivalence, this work also explores ways in which past-participants create diverse and hybrid Jewish identities and commitments for themselves, selectively making use of the information and experiences they acquire at Livnot . Is there any significance to ethnic experiences like Livnot , beyond the neat labels of essentialist, nostalgic, romantic searches for roots? Drawing on notions of resistance and agency, I suggest that Livnot offers participants knowledge and experience that empowers them to make informed Jewish decisions following the program. In this sense, Livnot provides participants with agency by enabling them to pick and choose from Jewish tradition, in order to fashion their own creative, personal Jewish identities.

abstract: Doctor of Philosophy (PhD)


title: Deadly Choices: Women's Risk for HIV Infection in a Truck Stop-Trading Centre in Rural South Western Uganda

contributor:
Willms, D.G.
Anthropology

subject: Anthropology Anthropology

abstract:
This document is an ethnographic product of a study funded by the International Development Research (IDRC) called "Talking About AIDS: The Lyantonde Study Group." This research project has been located in Lyantonde, a truck stop and trading centre devastated by HIV/AIDS. The study is a "deeply qualitative endeavour" involving an interdisciplinary team researching toward the development of culturally compelling interventions for persons vulnerable to or infected with HIV1 in rural SouthWestern Uganda. My goal is to elucidate the complexity of risks which confront women in that town on a daily basis. This is achieved through the stories of seven women who are compromised by fear, poverty and suffering. They live in fear of infection, anticipate signs of disease in themselves, and watch loved ones become sick and die.

There is an existing literature - clinical, epidemiological and social cultural - which locates women's risk for HIV/AIDS in a series of risk determinants. Many of these determinants are also revealed in the case studies. These include multiple sexual partners, the history of sexually transmitted disease, proximity to bars or hotels, and the effects of poverty.

Unfortunately, however, this literature does riot reveal the dilemmas that arise daily in these women's lives, or explain how they became compromised in the struggle between traditional expectations and their own personal wants and needs. Caught in situations of high risk, the grave decisions these women make for themselves and their families really are net decisions at all; they are choiceless choices, deadly choices. The case studies lend credence to the theoretical framework posited by Willms and Sewankambo (1994) who suggest that risk is better understood in a series of interconnected domains, namely, the risk reality, the risk situation, and the risk event.

The potential of intervening in a community so heavily devastated by HIV/AIDS lies in finding ways -- via multisectoral strategizing by community facilitators and external resource people to accommodate both ethnographically grounded understandings and ethnographically driven models of risk.

abstract: Doctor of Philosophy (PhD)


title: FcR expression and function in CD4⁺ T cell biology

contributor:
Snider, Denis P.
Health Sciences

abstract:
Receptors that bind immunoglobulin (Ig) via the Fc domain are known as Fc receptors (FcR). These receptors are integral transmembrane glycoproteins that are expressed on virtually every haematopoietic cell. FcR mediate a wide range of immunological functions from phagocytosis to cellular activation, however, the function and expression of FcR on CD4⁺ T cells is unknown. Thus, in vivo and in vitro studies were undertaken to investigate FcR expression and function on CD4+ T cells.

Previously it has been demonstrated that CD4⁺ T cells activated with antigen-pulsed macrophages or interleukin 1 (IL-1) generated IgG and IgA binding factors (IgGBF and IgABF). These immunoglobulin binding factors (IgBF) are one component of a soluble macromolecule, known as a contrasuppressor factor (CSF). These CSF act to augment IgG or IgA responses in vivo and in vitro in an isotype-specific manner. Serological and functional data presented here demonstrate that the IgGBF and IgABF are soluble FcϒRII/III and FcαR, respectively. sFcR could functionally substitute for the IgBF and enhanced antibody responses in an isotype-specific manner. Recombinant sFcϒRIII/III, at concentrations of 0.01 to 0.5 ng/mI could augment IgG PFC responses. However, at higher concentrations (10 to 100 ng/ml) it failed to augment IgG PFC responses. Furthermore, the enhancing activity of the IgBF/sFcR was mediated through a subset of T cells that adhered to the lectin Vicia villosa (Vv T cells). In xid mice, which are unable to generate CSF, T cells could generate the IgBF. However, the xid mice lacked circulating regulatory Ig (reg Ig) that is also necessary for the generation of the CSF, resulting in defective CSF.

Since activation of CD4⁺T cells induced the generation of sFcϒRII/III, I investigated FcϒR expression on CD4⁺ T cells utilizing an allogeneic activation system. FACS and PCR data from these studies demonstrated that alloactivation of purified CD4⁺ T cells with CH12.LXB cells induced de novo FcΥRIIBI expression within 24 hours and prior to DNA synthesis. The induction of FcΥRIIBI expression could be blocked by anti-MHC class II mAb, however, direct TCR ligation, even in the presence of IL-2, was not sufficient to induce expression. Moreover, the induction of FcΥRIIBi expression on CD4⁺ T cells was not dependent upon the Ig isotype of the CH12.LX B cells. Alloactivation of CD4⁺ T cells with different isotype-switch variants of the CH12.LX B cell line resulted in significant increases in the number of FcΥRIIB1⁺ CD4⁺ T cells. However, alloactivation with the IgG2b⁺ CH12.LX B cell line induced the largest number of FcΥRIIB1⁺ CD4⁺ T cells. Results from this study indicated that the IgG2b⁺ CH12.LX B cell line secreted a soluble factor(s) that augmented FcΥRIIB1 expression on aIloactivated CD4⁺ T cells. Although, the data suggests that this factor is not soluble IgG2b or IL-1, since both failed to induce FcyRIIBI expression on purified CD4⁺ T cells.

In conclusion, these data indicate that alloactivation of CD4⁺T cells induces de novo mRNA and surface expression of FcΥRIIBI within 24 hours and prior to DNA synthesis. In addition, CD4⁺ T cell FcΥRIIBI expression can be augmented by a soluble factor(s) secreted by the IgG2b⁺ CH12.LX B cells. Furthermore, activation of CD4⁺ T cells also induces the generation of sFcΥRII/III and sFcαR. These sFcR participate in the formation of CSF that enhance antibody responses in vivo and in vitro, in an isotype-specific manner, through the activation of Vv T cells.

abstract: Doctor of Philosophy (PhD)


title: SDMA/TDMA dynamic slot assignment using a smart antenna basestation

contributor:
Todd, Terence D.
Electrical and Computer Engineering

abstract: There is an increasing demand today for the deployment of wireless services such as cellular telephony, paging, wireless local area networks, digital broadcast television, and wireless Internet. The demand for bandwidth from these services continues to increase as more people adopt the technology and the applications become more sophisticated. In the recent years, researchers have demonstrated that smart antennas are capable of improving wireless link quality and increasing coverage area. In addition to this, it has also been demonstrated that smart antennas can permit the reuse of the frequency spectrum in the same wireless coverage area using space division multiple access (SDMA). SDMA has the potential to provide a tremendous increase in system capacity over conventional wireless systems. In this thesis we consider the application of smart antennas for packet switched SDMA networks. The system considered is an infrastructure network employing a smart antenna basestation which communicates with portable stations that have omnidirectional antennas. A time division multiple access (TDMA) packet switched system that incorporates SDMA is considered. Several heuristic dynamic slot assignment (DSA) strategies are proposed. DSA is the name given to the process of allocating packets to the time slots in real-time on a frame by frame basis. The primary objective of DSA is to maximize the frame capacity. Both a theoretical Rayleigh fading channel model and experimental data collected using an 8 element circular antenna array built at the Communications Research Laboratory at McMaster University is used to measure the frame capacity of the heuristics. Analytic, simulated, and experimental results demonstrate that the SDMA/TMDA frame capacity is several times higher than the single omnidirectional basestation antenna case. The results also provide insight into how the protocol performance is affected by parameters such as wireless channel model, slot assignment complexity, power control, pedestrian motion in the channel, and signal to noise ratio (SNR). The well known slotted ALOHA protocol which is best suited for bursty data communication between a large population of portable stations is adapted for operation with a smart antenna basestation. Versions of this protocol are considered where contention takes place in the data slot directly and when a reservation channel feeds a contention free data channel. The DSA heuristics developed earlier are applied to the contention free data channel to improve system capacity. An SDMA version of the slotted ALOHA protocol is modified for operation in a multicell situation. Simulation and analytic results show that the single cell slotted ALOHA system can achieve a many-fold increase in system capacity, especially when intelligent slot scheduling is done at the basestation. The sensitivity of the protocol capacity to factors such as the hardware complexity, packet size, SNR, and protocol complexity is examined. An analysis of the multicell slotted ALOHA protocol reveals that it is possible to reuse the frequency in every cell and still achieve a per cell capacity similar to ordinary single-cell slotted ALOHA with only a modest degree of smart antenna beamforming hardware at the basestations. The DSA heuristics are then extended to multicell situations. Several DSA techniques requiring various degrees of coordination between the basestations are examined. DSA enhancements are also proposed for systems with variable length packets.

abstract: Doctor of Philosophy (PhD)


title: Modeling, Sensing and Control of Workpiece Geometric Accuracy in Bar Turning

contributor:
Elbestawi, M.A.
Mechanical Engineering

subject:
Mechanical Engineering
Mechanical Engineering

abstract:
The ability to predict, measure and control the geometric accuracy of the machining process has become of significant importance to industry in its pursuit of successful competition in today's market place. This thesis describes the development and integration of the different subsystems required for the implementation of geometric adaptive control in bar turning. These subsystems include modeling of the machining system, on-line measurement of the workpiece geometry, tool actuation and predictive control design.

A mechanistic dynamic model of the machining system in bar turning is developed. The model accounts for the rather complex geometry of a multi-edged cutting tool and considers the dynamics of both the tool and workpiece. Also, the simulation of machining dynamics is significantly enhanced by incorporating a mechanistic ploughing force model which accounts for process damping. The model enables the simulation of the process for a wide range of cutting conditions and the prediction of cutting forces, workpiece accuracy and machined surface topography. The model predictions are verified using experimental results of turning hardened steel using ceramic inserts.

A novel non-contact sensor is then developed for on-line high speed monitoring of the workpiece diameter while using a cutting fluid. The measurement system employs three ultrasonic transducers and provides an absolute diameter measurement. An algorithm based on multi-probe measurements is developed to process the radius data and simultaneously compensate for sensor misalignment by tracking the center-line of the workpiece. The system is incorporated into a CNC lathe and provides an accuracy of±5 μm within a working range of 20 mm. The accuracy and repeatability of the measuring system are tested experimentally under realistic cutting conditions. The applicability of the measurement system to provide complete on-line assessment of workpiece geometry is also demonstrated by evaluating the workpiece geometrical tolerances. The influence of different parameters such as fitting objective functions, size of data sets, and data conditioning on such strategy are investigated.

A model-based predictive controller is designed and implemented to minimize the form error of the workpiece in bar turning. The mechanistic model of the machining system is simplified and reformulated into the state space to permit design and real-time implementation of the control system. The measurement system is set as close as possible to the cutting edge (at a distance of 0.27 mm). An optimal regulator with a Kalman Filter is designed. The on-line measurement of the workpiece diameter is used through the Kalman filter to update the model predictions with unmodeled process disturbances such as tool wear and thermal deflections of the tooling system. The system is implemented on a CNC lathe retrofitted with an Open Architecture Controller. The output of the geometric controller is used to govern the position of the tool tip in real-time by commanding the same servo motor which is driven by the preprogrammed G-code. The control system is tested experimentally under different cutting conditions and is found to provide a significant improvement of more than 90% in workpiece geometric accuracy.

abstract: Doctor of Philosophy (PhD)


title: Investigation of Protein-Protein and Protein-DNA Interactions Involved in the Function of Herpes Simplex Virus Transactivator Vmw65

contributor:
Capone, John P.
Biochemistry

subject: Biochemistry Biochemistry

abstract:
The herpes simplex virus phosphoprotein Vmw65 (also referred to as VP16, αTIF), strongly stimulates transcription through recognition of the cis-acting consensus sequence, TAATGARAT (R=purine), which is present in upstream regions of viral immediate early genes in at least one copy. However, Vmw65 has only weak intrinsic DNA binding activity. In order to execute its function as an activator, Vmw65 mediates the assembly of a multi-component complex with host cell factors that include Oct-1. The objective of this project was to utilize HSV-1 as a model system to investigate mechanisms involved in transcriptional regulation of eukaryotic genes, in particular, to elucidate how viral and cellular proteins are selected and assembled into transcriptional active complexes at the cis-acting sites through protein-protein and protein-DNA interactions.

Using affinity chromatography columns coupled with E. coli expressed protein A fused Vmw65, a novel cellular factor (referred to as VCAF-1), distinct from Oct-1, that bound directly to Vmw65 in the absence of target DNA was identified, and was found to be necessary for Vmw65-mediated complex assembly with Oct-1. This study also revealed that Vrnw65 does not form a complex, directly or indirectly, with Oct-1 in the absence of target DNA.

Some distinct properties of Vmw65 involved in generating functionally active multi-component complexes and their requirements for complex assembly and activation were investigated in vitro using mobility shift assays with ³²p-labelled oligonucleotides and purified components, as well as in vivo using CAT assays with mutant derivatives.

We found that Vmw65 has intrinsic DNA binding activity when used at a high concentration. This activity is sequence-specific and requires both regions 141-250 and 335-390 within the N-terminal complex forming domain (1-411). Vmw65 is able to cooperatively interact with DNA-bound Oct-1 in the absence of VCAF-1. The region containing amino acids 379-404 is required for cooperativity with Oct-1. The intrinsic DNA binding or cooperative interaction with DNA-bound Oct-1 may facilitate the assembly of multi-component complex. However, mutational analysis demonstrated that the abilities of Vmw65 to directly bind to DNA or interact with DNA-bound Oct-1 can be uncoupled from complex assembly and activation.

The independent interaction between Vmw65 and VCAF-1 may playa regulatory role in complex assembly and activation. Our study found that the sequence requirements for Vmw65 to independently interact with VCAF-1 overlaps but is distinct from that for complex formation. Furthermore, using amino acid substitutions, we demonstrated that the direct interaction of Vmw65 with VCAF-1 is not necessarily required for the formation of the multi-component complex in vitro, nor for the activation of IE genes in vivo. Our findings suggest that more than one pathway exists in cooperative assembly of the Vmw65 induced complex, and that selective protein-protein interactions may play important roles in differentiating these pathways. This may allow HSV to adapt to various physiological conditions of infected cells and regulate its productive life cycle.

The studies presented in this thesis have been reported, in part, in the following publications:

1. Xiao, P. and Capone, J.P. (1990) A cellular factor binds to the herpes simplex virus type 1 transactivator Vmw65 and is required for Vmw6S-dependent protein-DNA complex assembly with Oct-1. Mol. Cel. BioI. 10, 4974-4977.

2. Smibert, C.A., Popova, B., Xiao, P., Capone, J.P. and Smiley, J.R. (1994) Herpes simplex virus VP-16 forms a complex with the virion host shutoff protein. J. Virol. 68, 2339-2346.

3. Popova, B., Bilan, P., Xiao, P., Faught, M. and Capone, J.P. (1994) Transcriptional activation by DNA-binding derivatives of HSV-1 VP16 that lack the carboxyl-terminal acidic activation domain. Virol. 209, 19-28.

4. Shaw, P., Knez, J. and Capone, J.P. (1995) Amino acid substitutions in the herpes simplex virus transactivator VP16 uncouple direct protein-protein interactions and DNA binding from complex assembly and activation. J. Biol. Chem. 270, 29030-29037.

abstract: Doctor of Philosophy (PhD)


title: Nitridation and Interface Structures of Ni-Ti-N Alloys

contributor:
Weatherly, G.C.
Kirkaldy, J.S.
Materials Science and Engineering

subject:
Materials Science and Engineering
Materials Science and Engineering

abstract:
A two part study was conducted on the nitridation behaviour of dilute Ni-Ti alloys, and on the orientation relationships (OR)s and interfacial structures between TiN and Ni. Beginning with the Fickian relationships first proposed by Kirkaldy (1969) to describe internal sulphidation and assuming a solubility product of the form K=BC, these equations were combined to yield for the metal solute:

(δB/δt)=[Dʙ+(KDc/B²)](δ²B/δx²)

This second order differential equation shows that the concentration profile of the metal solute, B, is dependent not only on the diffusivity of the metal, Dʙ, but also on the solubility product K and on the gas diffusivity Dc. Two limiting cases were identified from the previous equation. The first which depends only on the metal diffusivity, Dʙ, corresponds to Wagner's (1952) error function solution for the superficial oxidation of alloys dilute in B. The second limiting case (Dʙ=0) corresponds to Wagner's (1959) oxygen controlled internal oxidation as proven analytically by Ohriner and Morral (1979). A criterion describing the transition from internal to external nitridation (oxidation) was deduced from the previous equation as:

(KDc/B₁²Dʙ)<0.1

where B₁ is the interfacial composition of the metal solute.

A finite difference algorithm was presented based on these ideas. A comprehensive test of this approach showed that it could generate the well known analytical solutions of Wagner's two limiting conditions. It was also shown that provided the solubility product K is small, Ohriner and Morral's (1979) analytical solution is valid even for an alloy not saturated in the gas phase (i.e. the composition need not be confined to the solvus of the ternary isotherm). As well as reproducing these analytical solutions, the model was successfully tested against the experimental work of Swisher (1968) and Kirkaldy (1969). A detailed investigation was conducted on the concentration profiles of Ti in Ni as a consequence of either internlal nitridation or superficial nitridation using Energy Dispersive X-Ray (EDX) analysis. It was found that the program always generated the correct shapes of the diffusion profiles as well the transition to external nitridation in the Ni-Ti-N system. Based on the measured interfacial composition of the interface, first time determinations of both KDN and DTi values were obtained between 800°C and 1020°C. The diffusivity of Ti in Ni is similar to other substitution solutes in Ni and can be expressed as

Dn=0.07 exp(-320000/RT) m²/s (900°C-1020°C)

where R is the universal gas constant 8.314 J/mole-K

A solubility product calculation of TiN in Ni showed values between 1.4 x 10ˉ⁶ and 5x10ˉ⁸ [w/o]² (between 1020°C and 800°C respectively). Using this data a diffusivity of N in Ni was obtained which compares favourably to other interstitial diffusivity data in Ni and ϒFe. The upper bound value for the diffusivity of N in dilute Ni-Ti alloys can be expressed as:

DN= 0.0003 exp(-17000/RT) m²/s (900°C-1020°C)

Stoichiometric TiN was the only precipitated phase found between 800°C-1020°C in this work. A first time investigation of the interfacial structure between TiN and Ni was conducted using transmission electron microscopy (TEM). It was determined that at least five different orientation relationships between TiN and Ni exist. All these ORs had relatively small near coincidence site lattice (CSL) relationships. The planar Σ value of Ni (δɴᵢ) with respect to the Ti sublattice were all found to be under 50. No correlation was found between the size of the CSL unit cell and the frequency of observation of a particular OR. In only two cases were misfit dislocations observed. Both O-Iattice and plane matching theory made correct predictions as to the misfit dislocation configurations. In both cases one predominate set of dislocations was calculated. It was not possible, however, to unambiguously identify the Burgers vector. The habit planes were dominated by {010}TiN indicating that this was an important factor in selecting the morphology and orientation relationships of these particles. This plane coincided both with a primary O-lattice plane and, as already noted, with a planar CSL relationship. These factors probably all play a role in the selection of these orientation relationships and habit planes in the Ni/TiN system.

abstract: Doctor of Philosophy (PhD)


title: A changing labour market: Empirical studies of self-employment

contributor:
Kuhn, Peter J.
Magee, Lonnie
Robb, Leslie A.
Economics / Economic Policy

subject: Economics Economics

abstract: Self-employment has risen dramatically in Canada, accounting for a disproportionate share of job growth since the early 1970's. This trend makes understanding this sector of the labour market imperative to understanding the overall labour market. This dissertation comprises three essays. The goal of the first two essays is to examine possible reasons for the trends in self-employment while the third essay quantifies and characterizes income tax non-compliance among the self-employed. In the first essay I assess the importance of macroeconomic conditions and the tax environment in explaining the trends in male self-employment in North America. I use microdata for the period 1983-1994 from Canada and the United States, which are perhaps more similar in overall institutional structure than any other two countries, but which differ substantially in their income tax policy, macroeconomic conditions, and self-employment trends. My findings suggest that higher income tax and unemployment rates are associated with an increase in the rate of male self-employment in the two countries. Changes in the tax environment account for a considerable amount of the secular trends in male self-employment over this period, while changing economic conditions played a smaller role in determining these trends. The second essay, which focuses on Canadian self-employment trends, examines the dynamics of self-employment among men and women using information on labour force transitions from 13 waves of the Survey of Consumer Finances between 1982 and 1995. The results show that the changes in transition patterns underlying the secular rise in self-employment in Canada were very different for women and men. For women, most of the increase in self-employment is attributable to an increase in their retention rates in self-employment. For men, most is attributable to a decrease in the stability of paid employment. The final essay provides estimates of the degree of income tax noncompliance by Canadian self-employed households using a series of Canadian Family Expenditure Surveys from 1969 to 1992. These estimates are disaggregated across years, demographic characteristics and occupation to shed some light on the determinants of such activities in Canada and to provide guidance to tax enforcement policy makers. My main findings are as follows. I find that the degree of noncompliance by the self-employed varies significantly by occupation, age and the number of household members self-employed. Further, there is no clear time trend in the estimates of noncompliance and education does not appear to influence these estimates.

abstract: Doctor of Philosophy (PhD)


title: EDUCATION AND IMPERIAL UNITY, 1901 - 1926

abstract: Doctor of Philosophy (PhD)


title: Neighbourhood Response to Community Mental Health Facility Locations

contributor:
Dear, M.J.
Geography

subject: Geography Geography

abstract:
The focus of this thesis is upon aggregate neighbourhood response to community mental health facilities. The mentally ill are increasingly being moved out of large institutional treatment settings to receive care from a range of small-scale facilities in the community. Opposition to facility locations has impaired the effectiveness of the community mental health movement and had important ramifications for the social and spatial structure of modern urban areas. Opposition represents a form of neighbourhood response to the perceived externality impacts of facilities exercised as communities act to protect their investment in the neighbourhood environment by territorially excluding the mentally ill. A thorough understanding of this aggregate group-based response is of critical importance to the continued operation of the community mental health movement as well as to our understanding of modern urban sociospatial structure.

This thesis develops and tests an operational model of nieghbourhood response. This model specifies a multi-stage process of facility impact and externality field perception which serves to determine neighbourhood response and ultimately, adjustments to the urban landscape. This process is related to a number of contextual variables representing the population surface of a host neighbourhood, the externality surface generated by a facility, and individual stake in the conflict issue. This model was tested using a sample of residents from Toronto, Ontario.

The findings indicate that community mental health facilities are perceived as having little impact upon residential neighbourhoods; some concern is apparent, however, over the effect of facilities upon residential property values. Perceived facility desirability tends to decrease with proximity to facilities, indicating the existence of an externality field conforming to a distance-decay relationship; the intensity and extent of this field is nonetheless highly constrained. The externality fields serve to arouse only a limited degree of opposition to facility locations. The propensity for response is related to perceived facility desirability, and increases with advanced proximity to the facility. No significant relationships between the perception and response processes and the analysis variables could be detected.

abstract: Master of Arts (MA)


title: Recall Using Well Known and New Relational Information

contributor:
Begg, Ian M.
Psychology

subject: Psychology Psychology

abstract:
The thesis examined the use of two kinds of relational information in the process of recall. Previously there has been separate study of the recall of items that share well known relations in permanent knowledge, and of items for which relations have been newly learned during study. Two approaches to explaining recall have evolved, each emphasizing the use of a different type of relational information. The thesis attempted to synthesize the two approaches into a single view of the process of recall.

Experiments 1 and 2 established that the two kinds of relations are independent sources of information in memory, and that both are used in recall. Experiment 2 demonstrated that well known and new relations are used differently in recall even when they are processed in the same study episode. Experiment 4 examined how the two sources of information can be used together to maximize recall. Experiment 5 extended the findings to a different way of establishing new relations between previously unrelated items.

The results suggested that the recall process makes use of whatever information is currently available in memory, including what was known previously and what was added in the course of study. It depends primarily upon any relevant permanent knowledge. If there are no permanently known relations to mediate recall, the process can occur by accessing the record of the new relation as it was formed at study. In addition, the different sorts of relations can combine forces to allow the recall of items that would not otherwise be accessible.

abstract: Doctor of Philosophy (PhD)


title: Frequency-Domain Optical Spectroscopy and Imaging of Tissue and Tissue-Simulating Media

contributor:
Patterson, Michael S.
Physics

subject: Physics Physics

abstract:
The goal of this work was to develop and study the use of a diagnostic in vivo tissue spectroscopy system based upon frequency-domain light measurements. Intensity-modulated light which is incident upon a scattering sample creates waves of light intensity which propagate through the medium in a manner which is dependent upon the scattering and absorption characteristics of the tissue. Detection of these waves at a point on the surface of the sample can be used to non-invasively estimate the scattering and absorption coefficients. Recovering these optical interaction parameters requires the use of a suitable model of light propagation in tissue, for which diffusion theory has been shown to work. The technical development of this system and the theoretical modelling are examined in this study. Some physiologically important chromophores can be detected within tissue using the spectral discrimination provided by a wavelength tunable source or detector. The quantification of chromophores can be used in dosimetry for therapeutic laser treatments or for diagnostic laser applications such as measuring hemoglobin oxygen saturation.

In addition to reflectance measurements, diffuse fluorescence can be detected from a scattering medium such as tissue if there is an active fluorescent molecule present. The theoretical modeling for diffuse fluorescence signals was developed and experimentally tested in a tissue-simulating phantom. There was excellent agreement between the theoretical model and the experimental tests with a fluorophore in a scattering emulsion. This work suggests that measurements of fluorescence lifetime or quantum yield can be made on a homogeneous tissue volume by deconvolution of the effects of multiple scattering.

Preliminary work was done on an optical tomography algorithm using measurements of phase and intensity at multiple points on a tissue surface to reconstruct images of the optical properties of the interior. Tomographic imaging is routinely done with x-rays for diagnostic imaging and recent developments suggest that a similar form of imaging can be accomplished with light, albeit with much poorer resolution and contrast. Frequency-domain measurements can provide a method for diffuse optical imaging through relatively thin tissue volumes (i.e., thickness less than approximately 10 cm). The theoretical development of a tomographic imaging system is examined in the final section of this thesis and tested with data from a tissue simulating phantom. The potential medical applications of such a system range from tissue oxygenation imaging to detection of cancerous regions within soft tissue.

abstract: Doctor of Philosophy (PhD)


title: Characterization of Rat Cells Transformed By Hybrid Adenovirus Type 5/12 E1A Genes

contributor:
Graham, Frank L.
Biology

subject: Biology Biology

abstract:
Previously, a series of hybrid adenovirus (Ad) type 5/12 E1A genes were constructed and used in combination with Ad12 E1B to transform primary Hooded Lister rat kidney cells. Research presented here describes the use of the resulting transformed cells lines to identify and characterize functional differences between Ad5 and Ad12 E1A proteins in an attempt to better understand the ability of Ad12 E1-transformed cells, unlike their Ad5 counterparts, to induce tumors in syngeneic immunocompetent rats.

At least two regions within the first exon of Ad12 E1A were identified which mediate tumorigenicity. Expression of either of these regions in the hybrid Ad5/12 E1A-(plus Ad12 E1B) transformed cells was associated with a decrease in cell surface major histcompatibility complex (MHC) class I expression, a finding which suggests that the tumorigenic capacity of Ad12 E1-transformants could be due to their ability to evade lysis by class I-restricted CD8⁺ cytotoxic T lymphocytes (CTLs). However, neither class I down-regulation nor sensitivity to allogeneic CTLs or syngeneic natural killer (NK) cells strictly correlated with the tumorigenic capacities of the hybrids, indicating that additional factors contribute to the differences in the oncogenic potential of rodent cells transformed by the E1 regions of Ad5 and Ad12. Further study demonstrated that at least two regions of Ad5 E1A encode CTL epitopes that confer susceptibility to syngeneic Ad5 El-specific CTLs in vitro while Ad12 E1A expression did not confer susceptibility to syngeneic Ad12 E1-specific CTLs.

The MHC class I enhancer is the target for Ad12 E1A-mediated down-regulation of class I transcription. In Ad12 E1-transformed rodent cells, the class I enhancer is primarily down-regulated through decreased binding of NF-kB (activator) and increased binding of COUP-TF (repressor). Using the hybrid Ad5/12 E1A- (plus Ad12 E1B) transformed rat cells, the same regions of Ad12 E1A implicated in tumorigenesis and down-regulation of class I expression were also found to mediate the differential binding activities of NF-kB and COUP-TF to the class I enhancer in Ad12 E1-transformants. Moreover, it was shown that reduced NF-KB binding activity was not due to decreased expression of its subunits, NF-kB1-p50 (or its precursor, NF-kB1-p105) or RelA-p65 nor to a defect in processing of NF-kB1-p105 to NF-kB1-p50. The latter discovery contradicts a previously published report in which it was suggested that decreased binding NF-kB to the class I enhancer in Ad12 E1-transformed cells was due to impaired processing of NF-kB1-p105 to NF-kB1-p50.

Finally, during studies designed to determine whether the different tumorigenic properties of Ad5 E1- and Ad12 E1-transformed cells were a result of alterations in the composition of their E1A-cellular protein complexes, it was discovered that expression of the Ad12 E1A regions implicated in mediating tumorigenesis, down-regulation of cell surface MHC class I expression, and differential binding of NF-kB and COUP-TF to the class I enhancer also correlated with the presence of a differential phosphorylated form of p300 in Ad12 E1- compared to Ad5 E1-transformed rat cells. This finding suggests that p300 function may be altered in Ad12 E1 - versus Ad5 E1-transformed rodent cells and raises the possibility that p300 may influence tumorigenicity through the regulation of MHC class I expression.

abstract: Doctor of Philosophy (PhD)


title: Sound Generation by a Centrifugal Volute Pump at Blade Pass Frequency

contributor:
Weaver, D.S.
Mechanical Engineering

abstract:
The behaviour of a centrifugal volute pump as a source of pressure pulsations as well as the role that the pump-pipeline interaction plays in the amplification of these pressure pulsations were experimentally investigated.

A test apparatus was designed and built which features acoustic tuning by pump shaft speed control, dynamic pressure measurements at different locations of the system and qualitative flow visualization capabilities.

A semi-empirical model based on a combination of a Green's function solution for the one-dimensional acoustic boundary value problem and a decay function, corresponding to the break down of large cortex structures in the cascade of turbulence, was developed to separate pressure pulsations of acoustic and hydraulic nature.

Flow visualization in the acoustic near field around the pump's cut-water region was correlated with the acoustic pressure pulsations. A study, parametric in Helmholtz number, relative pump flow rate and cut-water tip radius, was conducted.

Results pertain to the acoustic behaviour of a pump in a piping system:

The pump acts primarily as a pressure source that may be acoustically reflective or transparent depending on the prevailing flow conditions. The near field shows pulsing flow separation which occurs on either side of the cut -water depending on relative flow rate. For cut-water geometries with a clear separation point (sharp tip), a strong sound generation dependence on the relative flow is displayed. A well defined point of flow separation at the cut-water tip leads to the largest separation region and also the largest acoustic pressure pulsations. Rounding the cut-water has the effect to permit motion of the stagnation point, thereby reducing the size of the separation region as well as the acoustic pressure pulsations. Clearly, the geometrical details of the cut-water region play a significant role for sound generation without obvious changes in hydraulic performance.

abstract: Doctor of Philosophy (PhD)


title: Temperature-Dependcnt Growth of InP By Plasma-Enhanced GSMBE

contributor:
Thompson, D.A.
Engineering Physics

subject:
Engineering Physics
Engineering Physics

abstract:
This thesis reports on study of the effects of various plasmas on the growth of InP films by GSMBE. The samples were grown at temperatures ranging from 232 to 500°C. The plasmas were generated by electron cyclotron resonance, giving a broad distribution of ion energies in the 10-50 cV range. H. D, He and Ar plasmas were studied. Films were also grown at the same temperatures without plasma, as references.

The samples were characterized by: Nomarski phase contrast microscopy, Xray double crystal diffraction, Hall effect measurements, photoluminescence (PL), variable-energy positron annihilation, thermal desorption, nuclear reaction analysis and capacitance/voltage profiling. The Xray, Hall and PL measurements were repeated after the samples were annealed at 730°C for 10 seconds. In no case was the material produced of comparable quality to that grown under standard conditions (465°C, no plasma).

The films grown without plasma were n-type, reaching a carrier concentration of approximately 2x10¹⁸/cm³ at 300°C. This is in agreement with published results, which showed that the donor defect responsible is a P atom on an In site. This defect occurred in sufficiently high concentrations to mask the effects of the plasmas below 400°C.

H plasma increased the carrier concentration by approximately 7x10¹⁶/cm³. Some H atoms appear to bond to P atoms in the crystal, resulting in an excess In electron. The carrier concentration was not affected by annealing. Additional H atoms may be present as interstitials, causing a reduction in mobility and a broad PL peak near 1.05 eV. These effects were removed by annealing.

D plasma produced similar effects to H plasma, but the carrier concentration and mobility were lower. P interstitials, which act as deep acceptors, may be produced by recoiling surface P atoms into the bulk. Beryllium dopant, at a concentration of 2x10¹⁸/cm³), was passivated by this plasma. Silicon dopant was not strongly affected.

He plasma produced P interstitials and P vacancies, by recoil displacement from the surface and in the bulk. More P interstitials were produced, compensating up to 10¹⁷/cm³ carriers. The interstitials were more mobile, diffusing out during the 500°C growth and during annealing.

The effects of the Ar plasma were small enough to be masked by the weak H plasma that results from H backstreaming.

Films grown at 400°C or less without plasma had textured surfaces. The plasmas usuaIly smoothed the surfaces at these temperatures, resulting in defect densities lower even than occured at 465°C without plasma. Above 400°C. none of the plasmas significantly affected the surface defect densities.

abstract: Doctor of Philosophy (PhD)