title: Metal sulfides in oxidizing freshwater systems

contributor:
Kramer, J.R.
Geochemistry

subject: Geochemistry Geochemistry

abstract: The overall goal of this research project was to examine the occurrence and fate of S(II-) and associated trace metals in aqueous systems under oxidizing conditions, specifically freshwater sediments and surface waters. Three studies were conducted that examined the following: (a) the fate of Ag(I) sorbed to FeS(s) and the stabilization of S(II-) by Ni(II), Mn(II), Cu(II) and Zn(II) upon oxidation of an FeS(s) suspension, (b) the stabilization of S(II-) in oxic solution by Zn(II), Fe(II), Fe(III), Cu(II) and Ag(I) in association with Suwannee River fulvic acid (SRFA), and (c) the applicability of the colourimetric methylene blue-sulfide (MBS) method to the determination of trace S(II-) in oxic freshwaters. Silver(I) added to an aqueous FeS(s) suspension was scavenged from solution by the solid phase. Upon oxidation of the Ag-FeS(s) suspension, S(II-) concentration in solution rapidly decreased while Ag(I) was released back into solution. Similar experiments were repeated with added amounts of Ni(II), Mn(II), Cu(II) and Zn(II) to examine the effect of these metals on S(II-) in solution during FeS(s) oxidation. Zinc(II) in the presence of FeS(s) retarded the loss of S(II-) from solution, suggesting the stabilization of S(II-) by Zn(II) under oxic conditions. Sulfide did not appear to be stabilized by the other metals as concentrations decreased below detectable levels. In the case of Cu(II) and Ni(II) however, stable metal sulfide species may have formed and persisted under oxic conditions, but were not reacted and detected in the MBS analysis. Sulfide in aqueous solution in the absence of metals, with and without SRFA, decreased over time under oxic conditions due to reaction with oxygen and/or NOM. Zinc(II) was able to bind and stabilize S(II-) in the presence of NOM under oxic conditions, and this effect was attained even when other S(II-) binding metals, Fe(III) or Ag(I), were added to the sample. It was not, however, clear whether the association of Zn(II) with SRFA offered more stability to S(II-) than the Zn(II) alone. Iron in either oxidation state (II, III) did not stabilize S(II-) under oxic conditions regardless of whether NOM was present. Although Ag(I) and Cu(II) were both able to bind S(II-), even in the presence of NOM, it was not possible to assess whether these metals stabilized S(II-) under oxic conditions. In the presence of Ag(I) and Cu(II), MBS formation was inhibited in the acidic colourimetric reagent (MDR) and S(II-) could not be determined. Using the methylene blue method of S(II-) determination (MBS), S(II-) was measured at low nanomolar concentrations in a number of natural freshwater samples of varying organic carbon content. This study revealed a number of limitations in the application of the MBS method to the measurement of S(II-) in natural samples. Most significantly, total S(II-) concentration was underestimated by this method, as S(II-) bound to Ag(I) and Cu(II) and possibly other metals, was not readily reactive in the colourimetric reagent to form the methylene blue complex. Pretreatment of the sample with Cr(II) to reduce such metal sulfide species, resulted in higher S(II-) recoveries relative to MBS. Particulates and NOM contained in samples interfered with absorbance measurements, while adsorption of metal sulfide species to container surfaces caused S(II-) concentrations to be underestimated.

abstract: Doctor of Philosophy (PhD)


title: Automatic Image Processing System for Nuclear Film Detectors

contributor:
Kennett, T. J.
Physics

subject: Physics Physics

abstract:
A system to process automatically nuclear film detectors was developed by interfacing a commercial television camera to a computer and analyzing the two level images of white objects on a dark background.

Two analysis methods were used; it is concluded that they have different ranges of application. For intermediate to high fluencies (> 100 impacts/mm²) the antitransformation of the white line length distribution function obtained throughout a raster scan provides results with uncertainties smaller than the statistical fluctuations of the hole density in the film. For fluencies down to 20 impacts/mm² a direct image analysis gives more accurate results in reasonably short times. The limiting factor for very low fluencies is the resolution of the television camera.

abstract: Master of Science (MS)


title: Community health impacts of a petroleum refinery in Oakville, Ontario

contributor:
Taylor, Martin S.
Geography

subject: Geography Geography

abstract: This thesis examines community reappraisal of a petroleum refinery in Oakville, Ontario. Residents' concerns about the health impacts from refinery emissions led to a community health study in 1992. The results showed that residents' perceptions of refinery odours were associated with elevated levels of reported ill-health in the community. In response to community concerns, between 1992 and 1997, the refinery implemented extensive measures to reduce odorous emissions. The implementation of these odour reduction measures provided the basis to investigate residents' reappraisal of the refinery following the intervention. The significance of this research is based on a recognition of the importance of the role of the reappraisal process in environmental stress theory, and the relative absence of studies of this process in the environmental stress literature. Hence, using a longitudinal design and mixed-methods (i.e., quantitative and qualitative), the following objectives were addressed: (1) to determine the impacts of emissions from the Oakville Petro Canada refinery on the health and well-being of residents in the surrounding community; (2) to compare the impacts of emissions before (1992) and after (1997) implementation of odour reduction measures; (3) to relate pre-post changes in odour perception/annoyance and ill-health reporting to personal and situational factors; and, (4) to explore residents' responses and coping strategies after the implementation of the odour reduction measures. The quantitative data come from two cross-sectional health surveys across three comparable zones in 1992 (n = 391) and 1997 (n = 427). The quantitative analysis focused on examining changes in impacts, and the determinants of change in relation to the characteristics of the exposure. The qualitative analysis (n = 29), focused on exploring refinery-related experiences, coping strategies and concerns within the broader context of residents' everyday lives. Overall, both the quantitative and qualitative analyses show that despite the improvements in refinery impacts, some residents still view the refinery as a threat to their ways of life. Proximity to the refinery and the mediating role of odour perception and annoyance emerge as strong determinants of the observed changes in refinery effects over time. Uncertainty and lack of trust also emerge as salient factors determining residents' shifting concerns, coping strategies and reappraisal of the refinery. This study makes contributions to the environmental stress theory and risk perception literature by focusing on residents' reappraisal of an environmental stressor in relation to changes in the characteristics of the exposure. The study also makes methodological contributions by demonstrating the value of using mixed-methods in environment and health research. For practice, the persistence of residents' concerns means that the Community Advisory Committee to Petro Canada and the refinery in their risk communication and management efforts, must do more than disclose technical information(complaint statistics) and give due consideration to the way the people respond to risk information. For future research a more explicit focus on how coping strategies vary in different places and with different types of exposures is warranted.

abstract: Doctor of Philosophy (PhD)


title: A study of water quality, zooplankton and macrophytes in wetlands of the Canadian Great Lakes basin: Implications for the restoration of Cootes Paradise Marsh

contributor:
Chow-Fraser, Patricia
Biology

subject: Biology Biology

abstract: The overall objective of this study was to provide information on the ecology of coastal wetlands of the Great Lakes. Very little is known regarding the ecology of these highly productive and unique ecosystems. In particular, the aim was to assess the restoration of Cootes Paradise Marsh (via carp exclusion) by looking at zooplankton and how they are affected by water quality and habitat structure. Sixty additional marshes in the Great Lakes basin were visited to assess the quality of Cootes Paradise relative to these wetlands and to provide wetland managers throughout the basin with a large database with which to compare the restoration and degradation of other threatened marsh habitats. This study describes how aquatic macrophytes and lower trophic levels are affected by water and sediment quality and how wetland quality is influenced by 2 major anthropogenic stressors: land-use and carp. Ultimately, an index (WZI) was developed using the zooplankton community as indicators to aid in the assessment of wetland quality. Because the database we used to develop the index included wetlands from all four Canadian Great Lakes, including a diverse range of wetland quality, wetland types and geomorphological settings, it should be widely applicable across the Great Lakes basin. Detailed comparisons of water quality, macrophyte and zooplankton communities showed that there were significant improvements in wetland quality observed in shallow and protected areas of Cootes Paradise Marsh following carp exclusion; however, open and exposed sites remained unchanged and the quality of this coastal marsh was low to moderate relative to high quality marshes existing elsewhere in the Great Lakes basin. Carp exclusion alone was not responsible for these observed changes, and therefore, further remedial actions will be required to increase the functional capacity of this degraded coastal wetland.

abstract: Doctor of Philosophy (PhD)


title: A structure-function relationship study involving the first epidermal growth factor-like domain of human coagulation factor VII

contributor:
Blajchman, Morris A.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: The interaction of circulating coagulation factor VII with cell surface associated tissue factor (TF) is critical for the initiation of blood coagulation, and appears to play a significant role in several other biological processes. Thus, an understanding of the mechanism of this interaction should provide valuable insight into the development of these important processes. The first epidermal growth factor-like domain (EGF-1) of factor VII is the principle contact site with TF and possesses the structural elements characteristic of the ubiquitous EGF-like motif. The aim of this thesis was to investigate the relationship between the conformational structure of the EGF-1 domain in factor VII and its function in the initiator complex. Recombinant generation and analysis of a naturally occurring factor VII EGF-1 mutant (N57D) indicated a protein deficient in its cellular secretion, as well as possessing compromised procoagulant activity and TF binding capability. Using structural investigative techniques, this mutation was found to compromise the appropriate conformation of the EGF-1 domain via the loss of a previously undescribed, structurally-important intermolecular hydrogen bond, highlighting the delicate balance between conformation and function in this domain. Once developed, these structural investigative techniques allowed further investigation, indicating the EGF-1 domain adopted a conformation specific to the "active state" of factor VIIa and requiring the presence of calcium and the adjacent Gla domain. Once activated, occupation of the active site of factor VIIa with substrate-like inhibitors resulted in further conformational changes to the EGF-1 domain, indicating the presence of a novel active site occupant-specific allosteric linkage between the EGF-1 domain and the active site. This allosteric link also appeared to affect the functional processes of TF binding and enzymatic activity of the factor VIIa molecule. Overall, this study has contributed new knowledge on the relation of structural elements of the factor VII EGF-1 domain to the important factor VIIa functional processes of TF binding and enzymatic activity. As well, the study indicates a novel role for the EGF-1 domain in the unique co-factor mediated specificity observed for factor VIIa.

abstract: Doctor of Philosophy (PhD)


title: The influence of a tentative diagnosis on the identification of features from patient appearance

contributor:
Brooks, L. R.
Psychology

subject: Psychology Psychology

abstract: The clinical signs that a physician can identify from the appearance of a patient represent an important source of information, upon which the diagnostic decision is nominally based. Most of the research in medical education emphasizes the organization of medical knowledge or the reasoning processes based on these signs. This emphasis carries the implicit assumptions that identifying features is not the major problem and that evaluation of the clinical signs occurs largely independently of consideration of the diagnosis. However, there is accumulating evidence to suggest that the identification of these clinical signs can be influenced by the diagnosis being evaluated. The studies in this thesis contribute to this body of research by investigating the underlying processes by which the diagnosis being considered influences feature identification. Participants in these experiments were asked to identify the clinical signs from photographs of patients or electrocardiogram strips after having been biased towards the correct or an alternate diagnosis. It was found that the availability of a diagnosis served both to change the probability of reporting relevant clinical signs as well as to influence the identification of ambiguous signs. Manipulating the credibility of the suggested diagnosis, subsequently suggesting a second diagnosis, or decreasing the size of the pool of alternatives available to the diagnostician had a large impact on diagnostic conclusions, but produced relatively small effects on the features reported. These results suggest that changing the degree of focus that a clinician places on the suggested diagnosis has a small effect on the identification of the features by comparison to the substantial effect of merely suggesting a diagnosis. Furthermore, it was found that the subsequent suggestion of a competing diagnosis did not lead to a reinterpretation of the data. This indicates that once clinicians have seen the evidence one way, they are unlikely to see and label it differently. The implication of these findings for research on medical decision making, the mental organization of medical categories, as well as medical education are discussed.

abstract: Doctor of Philosophy (PhD)


title: Understanding the links between work commitment constructs

contributor:
Hackett, Rick D.
Business Administration

subject: Business Administration, Management, and Operations

abstract: This study investigated the conceptual distinctiveness and causal links (based on Randall and Cote's (1991) model) between organizational commitment (OC), occupational commitment (OcC), job involvement (JI), work involvement (WI), and intentions to withdraw from the organization and from the occupation. The process involved exploratory and confirmatory factor analyses which supported the distinctiveness of the constructs. Results suggest that WI affects both OC and OcC indirectly through its effect on JI. Furthermore, JI affects intention to leave the organization indirectly through its effect on OC, and affects intention to leave the occupation indirectly through its effect on OcC. Analyses also suggest that OC and OcC have direct and indirect effects on both forms of withdrawal intentions. Theoretical and practical implications are discussed.

abstract: Doctor of Philosophy (PhD)


title: Surface acoustic wave filters on diamond layered structures

contributor:
Smith, Peter M.
Electrical and Computer Engineering

subject:
Electrical and Computer Engineering
Electrical and Computer Engineering

abstract: Surface acoustic wave (SAW) devices are an enabling technology for high-performance wireless communication systems. They are able to meet performance specifications that are beyond the scope of competing technologies, particularly in the front-end of the receivers, and establish the ultimate performance that is achievable. Current spectrum congestion is forcing a move to higher operating frequencies, and this is leading to a search for low-cost SAW devices that are able to operate at frequencies above 2 GHz. To this end, there has been considerable interest in devices that employ the high acoustic velocity of diamond. Diamond, however, is not piezoelectric, and it must be layered with other materials such as zinc oxide (ZnO) to permit the electrical generation and detection of acoustic waves. There is therefore a need for modeling tools that accurately predict the behaviour of multi-layered SAW substrates in the presence of surface transducers and reflectors. This Thesis presents a study of SAW propagation and generation under infinite periodic grating structures on multi-layered ZnO/Diamond substrates. The study is based on the space harmonic method (SHM) and predicts the SAW behaviour under both open and shorted surface electrodes. Dispersion diagrams are obtained around the first Bragg wavenumber and stopbands of finite bandwidth are observed. The method is then extended to the generation of SAWS by interdigital transducers. Admittance curves and static capacitances are calculated. The physical propagation behaviour of ZnO/Diamond multi-layered substrates is also investigated. The displacement distributions and the standing wave patterns are calculated within each layer. The energy contained in each layer is computed for different propagation modes and different ZnO layer thicknesses. The results are interpreted within the framework of the coupling-of-modes (COM) theory. The COM parameters are derived for the first and second Sezawa modes as a function of aluminum and zinc oxide thicknesses. The results and the COM parameters can be directly used in the design of SAW devices. The established analytical treatments can be easily applied to other multi-layered substrates with an arbitrary configuration including additional layers.

abstract: Doctor of Philosophy (PhD)


title: Skeletal evidence of health and disease in pre- and post-contact alaskan eskimos and aleuts

contributor:
Saunders, Shelley
Anthropology

subject: Philosophy Philosophy

abstract:
A palaeopathological analysis of skeletal samples representing pre- and post-contact Alaskan Eskimos and Aleuts was conducted in order to 1) assess the pre-contact health of these groups; 2) investigate possible differences between the Eskimos and Aleuts in patterns of health and disease; 3) examine temporal changes in health; and 4) assess the biological effects of European contact on these populations.

The results obtained in the present study reveal that the Alaskan Eskimos and Aleuts suffered from a variety of health problems prior to contact, including iron deficiency anemia, fractures, non-specific infections, dental pathology, and congenital malformations. The data also suggest that the Eskimos and Aleuts had different patterns of health and disease prior to contact. Most notably, the Aleuts has significantly more cranial and overall trauma, and infracranial and overall infection than the Eskimos, while Eskimos had significantly more enamel hypolasia of the canines and lateral incisors than the Aleuts. Differences between these groups in their environment, warfare practices, housing, and subsistence pursuits may underlie this variability.

The skeletal data provide some evidence of declining health following contact, at least among the Aleuts. The introduction of new pathogens, particularly treponemal infection, likely contributed to the significantly higher frequencies of cranial infection and cribra orbitalia in the post-contact Aleut sample compared to the pre-contact sample. The post-contact Eskimo sample showed little evidence of declining health over time; however, historical accounts of epidemics and population decline clearly attest to the deleterious effects of contact on this population.

The present study illustrates the value of palaeopathology in providing insight into the health of the Alaskan Eskimos and Aleuts both prior to, and following contact. The valuable contributions of other sources of information, such as ethnohistory and epidemiology, are also recognized.

abstract: Doctor of Philosophy (PhD)


title: The immunomodulation of the enteric nervous system: The effect of cytokines on neurotransmitter release and content

contributor:
Collins, Stephen M.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
Inflammatory conditions of the gut, such as ulcerative colitis and Crohn's disease are associated with an alteration in intestinal motility. The mechanisms underlying altered motor function is unknown, but may be the result of alteration in smooth muscle and/or enteric nerve function. Recent studies using Trichinella spiralis (T.spiralis) infection of rats, as model of intestinal inflammation, have shown that the accompanying inflammatory response in these animals is associated with an altered enteric nerve function. These changes included a suppression of noradrenaline and acetylcholine release and an increased substance P content within the neuromuscular layer of the inflamed jejunum. Furthermore, there was an expression inflammatory cytokines within the mucosa and the deeper muscular layers of the jejunum within 12 hrs from the onset of T.spiralis infection. This elevation in cytokine expression occurred prior to the changes in myenteric neurotransmitters. It is therefore possible that inflammatory cytokines within neuromuscular layer cause a change in neurotransmitter release and content, and thus contribute to the altered gut motility observed in the nematode-infected rats.

Addition of exogenous IL-1β or TNFα to isolated longitudinal musclemyenteric plexus (LM-MP) preparations caused a suppression of stimulated noradrenaline release, which was tiem and concentration dependent. This suppressive action was biphasic in manner, displayign an early protein synthesis independent effect and a delayed protein synthesis dependent effect. Furthermore, the delayed suppressive action of these cytokines on noradrenaline release were dependent on prostanoid synthesis. On examination of a putative direct interaction between these cytokines and adrenergic nerves using a nerve varicosity preparations, only IL-1β was found to suppress the evoked noradrenaline release. This suppressive action by IL-1β was time- and concentration-dependent, and in part, mediated by prostanoids. Although incubation of TNFα alone with the varicosities was unable to induce a response, the presence of TNFα did potentiate IL-1β-induced suppression of noradrenaline release. The conclusions drawn from this study are that TNFα causes a suppression of noradrenaline release from myenteric nerves which is evident only in a multicellular preparation and ilkely involves intermediary cells and their products including prostaglandins and/or thromboxanes. This contrasts with IL-1β, which in addition to an indirect effect, also suppressed noradrenaline release by directly interacting with adrenergic nerve terminals.

IL-1β also caused an increase in substance P content within the myenteric plexus. The increase in this neuropeptide was time and concentration dependent, and could be depleted by scorpion venom. Immunohistochemical studies indicated that substance P was only found present within myenteric nerves. The IL-1β-induced increase in substance P was considered to be due to increased synthesis, since cycloheximide prevented the cytokine-stimulated increase substance P content induced by IL-1β. Moreover, the increase in substance P content was mediated by prostanoid synthesis, but not nerve growth factor. The conclusion drawn from these experiments is that IL-1β stimulates the synthesis of substance P within intrinsic nerves of the myenteric plexus.

A putative role of endogenous IL-1 in the alteration of neurotransmitters in the T.spiralis model of intestinal inflammation was examined using a selective IL-1 receptor antagonist (IL-1ra). Treatment of the animals with IL-1ra prior to T.spiralis infection attenuated the suppressed noradrenaline release and increased substance P content observed in the inflamed LM-MP preparations. Therefore the results fro these experiments and those preformed using exogenous IL-1β and TNFα support and notion that inflammatory cytokines alters myenteric neurotransmitters, resulting in a disruption of enteric nerve function and thereby contributing to alterations n intestinal motility.

abstract: Doctor of Philosophy (Medical Science)


title: Vers un ordre nouveau: The concepts of nation and state in the doctrines of the Faisceau and Croix de Feu/Parti social francais

contributor:
Thorpe, Wayne
History

subject: History History

abstract: This dissertation reconsiders traditional approaches to the interwar French extreme-right by emphasizing ideology, specifically plans for the transformation of the nation and state. It focuses upon proposals of this type produced by members of the largest extreme-rightist groups in 1920s and 1930s France respectively: The Faisceau and the Croix de Feu/Parti social français. Preferring to study them in organizational terms or as historical actors within the Third Republic, most historians have de-emphasized the ideological dimension of these groups, subordinating the study of ideology to group composition or political activities. When more fully examined, doctrinal precepts frequently are used to prove or disprove the fascist qualities of various individuals or groups. This work, in contrast, systematically examines the ideological dimension in a way that others have not, focusing upon attempts by the Faisceau and CDF/PSF to develop comprehensive plans for an extensive transformation of the French nation and state. Not only did this project command significant attention from group leaders and members, it was in fact the overarching goal behind their aspiration to power--to install a new regime designed according to group principles. Integrating existing scholarship, but simultaneously moving in new directions, the thesis also challenges the common assumption that both groups can be treated as monolithic, top-down organizations whose doctrine was that of their leaders. It instead emphasizes the factionalization of the Faisceau and CDF/PSF, that both groups were split between modernizing elements and traditionalist ones. Within the ranks of the Faisceau, for example, authoritarian conservatives like Hubert Bourgin, Jacques Arthuys, and Philippe Barrès consistently challenged leader George Valois's modernizing'left fascism' regarding the composition and function of the new state, the role of youth within the transformed nation, and the politics of exclusion. Similarly within the CDF/PSF, economic modernizers, proto-geneticists, and rabid anti-Semites challenged group leader Colonel de la Rocque's social Catholic and combattant faction. The dual purpose of the thesis is therefore to analyze plans for the nation and state created by various Faisceau and CDF/PSF members, while emphasizing the heterogeneity of doctrine in both groups. Each chapter discusses one aspect of the proposed transformation. Chapters one and two focus upon competing plans within the Faisceau and the CDF/PSF for a new state and economic order. Chapter three examines differing perspectives in both groups regarding new roles for women and families in the new nation, while the place of youth in the nation is examined in chapter four. The fifth chapter discusses the politics of exclusion in the plans of both groups, including the proposed removal of Jews, masons, and foreigners from the nation as 'undesirables'. This dissertation rests on an analysis of diverse materials, including newly available documents in the Fonds La Rocque at the Conservation historique éuropéene de vingtième siècle. In addition to CHEVS archives on Faisceau leader Georges Valois and CDF/PSF leader Colonel François de la Rocque, this dissertation draws upon sources from the Archives Nationales (both the F7 police files and the AP/451 La Rocque archive), the Paris Prefecture of Police, the Centre de documentation juive contemporaine, the Bibliothèque Nationale, and the Fondation nationale des sciences politiques. It also mobilizes various nonarchival sources, including published works, group newspapers, tracts.

abstract: Doctor of Philosophy (PhD)


title: Numerical simulation and experimental study of the behaviour of vortex rings

contributor:
Latto, Brian
Mechanical Engineering

subject: Philosophy Philosophy

abstract:
The research was directed at an understanding of the behaviour of vortex rings under more realistic and complex conditions than those considered previously. A numerical method using a control volume finite difference technique was employed to simulate vortex ring behaviour in various vessel geometries. Unlike in other studies, buoyancy effects were included. The flow behaviour of the fluids in a tank due to the formation and motion of the vortex rings was studied. Several computer models have been developed for numerical simulation of various conditions. The conditions that were simulated are: (1) the effects of injecting Reynolds number and Richardson number on the penetration of a laminar vortex ring through a stratified layer of sharp or linear temperature change along the interface; (2) the formation and motion of a single vortex ring ejected from a tube centrally located near fluid free surface of a cylindrical tank, for stratified non-Newtonian power law model fluids with Richardson numbers of 0.0, 0.01 and 0.1 and power law indices of 0.17, 0.571 and 1.5; (3) the formation and motion of primary and secondary vortex rings ejected from an orifice plate, centrally located in the bottom or middle level of a tank having thermally stratified water depth to tank diameter ratios of 1.695 and 2.77, with and without a peripheral gap around the generating plate.

The numerical results showed that: (1) the penetration and trajectory of a laminar vortex ring is virtually independent of the injection Reynolds number, but primarily dependent on Richardson number; (2) laminar vortex rings in a power law fluids behave inviscidly, virtually the same as in Newtonian fluids for a certain range of injecting Reynolds numbers; (3) secondary vortex rings generated at a plate type orifice have similar trajectories and vorticity intensities to those of primary vortex rings for a trapezoidal injecting velocity-time profile. This results in a the doubling of the mass transportation and most probably more efficient mixing; the vorticity created at the plate periphery and also along the vessel wall can have a notable effect on the behaviour of the primary and secondary vortex rings, and so does the vorticity at region remote from the generating device. The intensity of the vorticity created in this manner is dependent of parameters such as, peripheral gaps between the impeller and the vessel wall, the orifice size, and the velocity-time profile for the generating plate. This phenomenon has not been described before and appears to be of considerable interest for both fundamental and mixing studies.

Some empirical experiments have been preformed and there appears to be good agreement with the numerical simulation studies. The flow visualization clearly displays the formation and motion of the primary and secondary vortex rings, and rolling up, transportation, transition and turbulent decay of a laminar vortex ring within its travelling distance. Experimental results demonstrate that the behaviour of vortex rings and the interaction of primary and secondary vortex rings are very dependent on displacement-time motion profile of the generating device

abstract: Doctor of Philosophy (PhD)


title: A Bandwidth Efficient Digital Radio System

contributor:
Taylor, D. P.
Electrical Engineering

subject:
Electrical and Electronics
Electrical and Electronics

abstract: A feasibility study has been performed on a 4 bits/s/Hz digital radio system. This system utilizes a 4-level quadrature amplitude modulation scheme with Duobinary filtering to achieve such high bandwidth efficiency. The error rate performance of such systems is evaluated. A repeater structure including the transmitter and the receiver of such systems is developed and analyzed. A decision directed carrier recovery loop is presented and analyzed using stochastic techniques. Expressions for the effective phase detector characteristic and the steady state phase error probability density function are derived. A symbol timing recovery structure is also presented and exhaustive simulations have been performed to analyze the performance of the timing recovery structure.

abstract: Master of Engineering (ME)


title: Dynamics of loosely supported heat exchanger tubes

contributor:
Dokainish, M. A.
Weaver, D. S.
Mechanical Engineering

subject:
Mechanical Engineering
Mechanical Engineering

abstract: Tube failure due to excessive flow-induced vibrations is a major concern with regards to the operation of heat exchangers in nuclear power and chemical process plants. Typical consequences include unplanned and expensive plant shutdowns to plug the failed tubes. Fretting wear resulting from tube/support impact is considered as a major contributor to tube failure. Impact forces, which occur when tube vibration amplitudes exceed the local support clearance, play a vital role in determining tube wear. Turbulence is one of the possible excitation mechanisms which can drive tube vibrations and is of particular concern in heat exchangers. Unlike other excitation mechanisms, turbulence has a persistent effect and thus determines the long term reliability of the heat exchangers. To address these issues, a point contact algorithm describing the tube/support interaction was implemented in an in-house finite element program and validated by several published examples. Pseudo-forces were utilized in conjunction with modal superposition in solving the nonlinear equations of tube motion. The equilibrium equations were solved iteratively to calculate the contact forces required to oppose any tube/support overlaps. The impact model was further modified to consider more realistic tube/support contact configurations. The new model considers a finite support width. The contact forces arising from the tube/support overlap are due to two different contact situations that may be encountered (point and segment contact). A distributed stiffness along the tube/support interface was utilized to model the segment contact. The resulting contact pressure was calculated using the displacement profile along the contact segment. The general point contact model considers any tube/support overlap that may occur between the principal contact node and the neighbouring node. Time-domain simulations of the nonlinear response of the tube are presented to determine the effect of various tube/support parameters on the system's vibratory characteristics. Special attention was paid to the effect of clearance enlargement due to fretting wear on the response of tubes in lattice-bar supports. The tube response, the impact force, and the contact ratio (ratio of the contact time to the total time) were analysed and presented in a dimensionless form. The dimensionless parameters utilized proved to be effective at collapsing all the data pertaining to different flow velocities over a single curve. This aids in identifying the role of support variables in influencing tube dynamics. Moreover, these parameters may also be used to scale the results in order to account for differences in geometrical and material properties. In addition, simulations were conducted to investigate the effect of the support type, the flow orientation, and the lattice-bar offset on the tube dynamics. The study indicates that some flow orientations, support types, and support offsets provide a favourable support geometry for higher normal work rates. This, in turn, increases susceptibility to fretting wear damage. These results provide new insights and a better understanding of the underlying phenomena of nonlinear tube behaviour in loose lattice-bar supports.

abstract: Doctor of Philosophy (PhD)


title: The influences of local environmental factors on settlement and agriculture in Saltfleet Township, Ontario, 1790--1890

contributor:
Weaver, John C.
History

subject: History History

abstract: This thesis addresses the deficiencies of recent studies that principally employ cultural factors, such as religion and country of birth, to explain variations in wealth and property in nineteenth-century Ontario. Southern Ontario's "first land," an amalgam of particular environmental, climatic, and geophysical factors, presented settlers with a defined set of agricultural and economic possibilities. As settlement activities altered the natural surroundings, a new series of economic possibilities emerged, which in turn, required its own settler response. This relationship changed constantly. In Saltfleet Township, Ontario, the principle area of study for this thesis, the main economic activity was agriculture. A few decades of intensive farming negated the millennia required to enrich the soil with the matter necessary to sustain plant life, while deforestation exposed the ground to the eroding effects of rain and wind. These alterations required a change in the settlement landscape, broadly characterized as improved husbandry and crop specialization tailored to a farm's particular environmental characteristics. This combination of settlement and natural responses produced individual parcels of property with distinct characteristics, including soil fertility, climate, and distance to markets. Studies that seek to understand settlement and agriculture in southern Ontario cannot treat farmland as homogeneous, no matter how many qualifying statements are employed to acknowledge and then exclude these variations. In isolating local environmental variables, such as a farm's topography, drainage, distance to water, and location relative to the Niagara Escarpment, this thesis uses a new settlement model that emphasizes the importance of local environmental variations, the effect of which is only recognizable over a long period of time. What emerges is the importance of farmers' abilities to perceive changes in the land and market, and to act upon what they saw.

abstract: Doctor of Philosophy (PhD)


title: Stature, mass, and body mass index of Canadian children

contributor:
Herring, D. Ann
Anthropology

subject: Anthropology Anthropology

abstract: This study examines changes in the anthropometric measurements of stature, mass and the Body Mass Index (BMI) among Burlington, Ontario children during the last half of the 20th century. Few studies have investigated changes in these variables within a Canadian context; fewer still have examined them using a large mixed longitudinal sample of children conducted over a 20-year period (The Burlington Growth Study, 1952-1972). When the Burlington Growth Study profile (n = 1380) is compared to that for a contemporary sample of Burlington children (n = 252), it is evident that stature, mass and BMI have risen among children growing up in the 1990s compared to those who matured in the 1950s to 1970s. These increases, albeit small, are statistically significant (p < 0.001). The prevalence of overweight children has grown substantially as well, with a particularly striking two-fold increase in overweight girls (p < 0.001). These findings indicate that Canadian children are participating in the global rise in these variables, including an epidemic of children at risk for and already overweight. Tracking of BMI values for 220 children in the Burlington Growth Study over a nine-year period revealed significant associations for inter-age comparisons and BMI at age 14 compared to younger ages (p < 0.001). Further study of the "tracking" phenomenon may lead to the identification of a critical age for the onset of obesity and, in turn, to the development of appropriate age-specific public health interventions.

abstract: Doctor of Philosophy (PhD)


title: Motion command generation for multi-axis machining

contributor:
Spence,  Allan D.
Mechanical Engineering

abstract: In current industrial practice, the transformation of Computer-Aided Geometric Design surfaces into Computer Numerical Control (CNC) machine tool axis commands is performed with the aid of Computer-Aided Manufacturing software and a closed CNC machine tool controller. The advent of new technologies such as Open Architecture Control has enabled the rethinking of motion command generation. This thesis describes a five-axis motion command generation architecture and algorithms in which a parameterized tool-path is interpolated off-line and the inverse kinematics mapping is performed in real-time, on the CNC controller. This architecture eliminates the need for time consuming repost-processing of the tool-path in the event of kinematic changes and additionally introduces the benefits of parametric splines with controlled feedrate. To deterministically attain a near constant feedrate tool-path, near arc-length parameterized splines are prepared off-line. The C2 position spline which is near arclength parameterized improves on the previously reported research. The orientation unit vectors are interpolated with a C 2 spherical Bézier spline. These two splines are then synchronized by means of a monotonic reparameterization spline. This results in reduced effective feedrate oscillation. The interpolated tool-path and axis commands are demonstrated to be smooth and C2 continuous. To cope with actuator saturation, a feedrate interpolation algorithm is developed which ensures C2 continuity but allows the feedrate to be adjusted as needed. The developed algorithms were simulated for two tool-paths and two five-axis machines tools. A test part was cut to demonstrate geometric correctness.

abstract: Doctor of Philosophy (PhD)


title: The influence of differentially processing evidence on diagnostic decision-making

subject: Psychology Psychology

abstract: By definition, the act of decision-making requires the consideration of multiple alternatives. Medical decision-making is no exception in that to decide whether or not a particular diagnosis is probably correct, a clinician must consider other diagnostic possibilities. Failure to do so is referred to as premature closure. If clinical instruction is provided regarding this diagnostic hazard, it tends to consist of advice to think of differential diagnoses before concluding one's diagnostic search. However, it is not yet known if such instruction is effective, let alone sufficient to eliminate diagnostic errors that arise from the tendency to under-weight non-focal hypotheses. I examined this issue by presenting case histories to experimental participants and manipulating the diagnoses that were explicitly presented with a request to assign probability ratings, a paradigm extensively used by Tversky and Koehler (1994). Fluctuations in the probability assessments provided an empirical measure of the degree to which diagnostic hypotheses were considered when they remained implicit in an "all other diagnoses" category. Results showed that diagnosticians tend to under-weight diagnostic alternatives that they are not explicitly asked to evaluate (Experiments 1 & 2). Furthermore, this effect does not solely arise from non-generation of alternative diagnoses. Diagnoses that medical students themselves generate are under-weighted relative to when the same diagnoses are presented explicitly (Experiment 3). By extension, this suggests that educational instruction to 'consider alternatives' is insufficient to help students eliminate premature closure. I hypothesized further that premature closure might result from a confirmation bias because the explicit presentation of a diagnostic alternative might cause diagnosticians to differentially process the evidence relevant to the diagnostic possibilities. That is, judges might focus their attention on the signs and symptoms of a case that are consistent with the diagnosis they are asked to evaluate at the expense of reducing consideration of the information consistent with other hypotheses. The results of Experiments 4 to 6 support this hypothesis. In these experiments it was found that participants who were prompted to re-evaluate the evidence were less susceptible to the biasing influence of the explicitly presented alternatives as long as this re-evaluation took place at the moment of decision-making. This was true even though no additional information was provided through prompting. Finally, additional factors that might lead to biased processing of the available evidence were examined. Formal medical terminology will cause differential processing, possibly because it is more mnemonically effective (Experiment 7). Diagnosticians are less susceptible to under-weighting non-focal alternatives when they themselves generate the focal hypotheses (Experiment 8). And finally, the diversion of attention created by the explicit mention of a specific diagnosis is not driven purely by an analytic shift of attention towards that particular diagnosis. Non-analytic influences are also influential (Experiment 9). The importance of these results for medical education and psychological theory of subjective probability is discussed.

abstract: Doctor of Philosophy (PhD)


title: The maturation and experience-dependent plasticity of the developing visual cortex

contributor:
Murphy, Kathryn M.
Psychology

subject: Psychology Psychology

abstract: During early postnatal development the visual cortex undergoes substantial anatomical and physiological maturation that has direct implications for the emergence of the various visual acuities. A large body of research has studied this early development, in particular the role of visual experience during development. Surprisingly, a relatively simple aspect of development--growth--has received very little attention. The results from Chapter 2 of this thesis show that there is substantial postnatal growth of the mammalian visual cortex and that this growth is best described as a simple uniform expansion. The development of visual acuities occurs during early postnatal life as a result of the maturing neural circuitry of the visual system and normal binocular visual experience is important for this maturation. Disruption of binocular vision during this period leads to changes in neural circuitry and can result in permanent visual impairments. Numerous studies have demonstrated that a key post-synaptic component of experience-dependent plasticity is activation of the NMDA receptor. In the present set of studies, a monoclonal antibody was used to label neurons expressing the obligatory NMDAR1 receptor subunit in the visual cortex to study the normal development and affect of visual deprivation on the distribution of this population of neurons. Results from the experiments in this thesis show that in normal kittens, there are regularly spaced patches of NMDAR1 expression across the supragranular layers of the visual cortex. These NMDAR1 patches are both spatially and functionally linked to binocular vision. Reducing binocular correlation by monocular deprivation led to a visuotopic loss of NMDAR1 expression whereas reducing visually driven activity, but not binocular correlation by binocular deprivation led to a generalized increase in NMDAR1 expression that may represent a homeostatic response. These results show that NMDA expression is experience-dependent and can be modulated by both the amount and pattern of visual experience. Recovery of NMDAR1 expression after deprivation was promoted by simply introducing binocular vision, however, reverse occlusion did not promote recovery. The results of this thesis may be related to the results of previous anatomical, physiological, and behavioural studies of deprivation that have found visuotopic changes. Furthermore, these results have important implications for the experience-dependent development of the visual cortex and visual functions because of the key role that the NMDA receptor plays in the establishment of functionally relevant neural circuitry.

abstract: Doctor of Philosophy (PhD)


title: Precipitation polymerization of divinylbenzene to monodisperse microspheres: An investigation of the particle formation mechanism

contributor:
Stover, Harald D.
Chemistry

subject: Chemistry Chemistry

abstract: This thesis addresses how the interactions between the reaction solvent and the forming polymer affects the morphology of the polymer formed in crosslinking polymerizations. Specifically, the mechanisms of nucleation, stabilization, growth and desolvation have been studied in the precipitation polymerization of divinylbenzene to monodisperse microspheres. These polymer beads have diameters in the micrometer range and may prove usefully for applications such as the separation of chemical mixtures using porous microspheres. The nucleation mechanism was found to proceed through transient microgels that are produced both by intermolecular reactions between oligomers and by further propagation. These microgels are transient and disappear from the reaction mixture at the same time as microspheres appear. This suggests that the microgels are the nuclei that grow to become the final microspheres. Internal curing reactions throughout the course of the polymerization transform the soft and deformable microspheres observed early in the reaction, into the rigid microspheres observed at the end of the reaction. As a result of both the nucleation and growth processes and the solvency of the polymerization medium, the microspheres have a gel surface that is formed in situ. When swollen with good solvents this surface gel serves as a steric stabilizer and when collapsed the microspheres flocculate together. Using a seeded polymerization method, the microspheres were shown to grow by a reactive growth mechanism. Oligomers were captured continuously from solution by radical reactions with existing microspheres. In contrast, microspheres having inert alkyl groups on their surface did not grow. Instead secondary or continuous nucleation was observed to produce new, smaller microspheres with broad size distributions. The microspheres observed in precipitation polymerization were then related to the morphologies more commonly observed in crosslinking polymerizations: microgels, macrogels, and coagulum. The volume occupied by the polymer was observed to decrease both with decreasing solvency of the continuous phase and with increasing crosslinking monomer concentration. Crosslinking in near theta-solvents was determined to be responsible for contraction of the polymer network into dense microspheres. The contraction of the polymer network is likely progressive, supporting the presence of a lightly crosslinked corona around the microspheres that acts as a steric stabilizer.

abstract: Doctor of Philosophy (PhD)


title: Renovating Baconianism, reading Bacon: The fathering of science

contributor:
Bowerbank, Sylvia
English

subject:
English Language and Literature
English Language and Literature

abstract: While Francis Bacon has come to be known as modernity's herald, the putative "father" of experimental scientific method, this commonplace notion has come to serve scholars, both within and beyond the confines of Bacon Studies, as a means by which to circumvent, rather than to scrutinize, his most important scientific texts. As a result, constructions of Bacon's thought today have come to diverge markedly from the texts that they claim to represent, often asserting on Bacon's behalf claims that Bacon himself would not only have rejected, but which at times he can be seen to directly refute. The task of this thesis is threefold. Chapter One seeks to establish a strategy for reading Bacon's text that critiques the received wisdom concerning Bacon's utilitarianism and empiricism. This received wisdom is predicated on the failure to read--in perfectly literal terms--Bacon's text. In this regard, I elaborate a reading methodology in which Bacon's text is placed alongside Bacon Studies, creating a situation in which Bacon quite literally refutes the critical claims that have come to represent his thought in the twentieth century. Chapter Two proceeds to offer a revised reading of Bacon's text itself. I dwell specifically on the theoretical nuances of the Instauratio Magna , elaborating on Bacon's articulation of scientific method that takes into account the theoretical presuppositions of his thinking. Eminently self-evident constituents of Bacon's philosophical itinerary--induction, experiment, natural history, etc.--are cast in a new light when contextualized according to their place in Bacon's extended argument for a renovated natural philosophy. Chapter Three suggests that, far from being the precursorial "father" of modernity, Bacon is still fathering it. Bacon's striking relation to the thought of Thomas Kuhn offers a new way to conceive of Bacon's continued impact on, and continued structuring of, the manner in which we produce scientific knowledge today.

abstract: Doctor of Philosophy (PhD)


title: Stochastic optimization models for service and manufacturing industry

contributor:
Gupta, Diwakar
Management Science/Systems

subject: Management Sciences and Quantitative Methods

abstract: We explore two novel applications of stochastic optimization inspired by real-world problems. The first application involves the optimization of appointments-based service systems. The problem here is to determine an optimal schedule of start times for jobs that have random durations, and a range of potential cost structures based on common performance metrics such as customer waiting and server idling . We show that the problem can be formulated as a two-stage stochastic linear program and develop an algorithm that utilizes the problem structure to obtain a near-optimal solution. Various aspects of the problem are considered, including the effects of job sequence, dependence on cost parameters, and job duration distributions. A range of numerical experiments is provided and some resulting insights are summarized. Some simple heuristics are proposed, based on relaxations of the problem, and evidence of their effectiveness is provided. The second application relates to inventory deployment at an integrated steel manufacturer (ISM). The models presented in this case were developed for making inventory design-choice (what to carry) and lot-size (how much to carry) decisions. They were developed by working with managers from several different functional areas at a particular ISM. They are, however, applicable to other ISMs and to other continuous-process industries with similar architectures. We discuss details of the practical implementation of the models, the structure of the problems, and algorithms and heuristics for solving them. Numerical experiments illustrate the accuracy of the heuristics, and examples based on empirical data from an ISM show the advantages of using such models in practice and suggest some managerial insights.

abstract: Doctor of Philosophy (PhD)


title: Changing places: Landscape and mortuary practice in the Irish Middle Bronze Age

contributor:
Ramsden, P.
Anthropology

subject: Anthropology Anthropology

abstract: This thesis explores an Irish Middle Bronze Age landscape using quantitative spatial analysis as a starting point for broader contextual discussion. The main data set is the distribution of a concentration of ring ditches, which are one end product of a complex burial rite. The concentration was formed throughout the second millennium BC. Other data on terrain variation and change was also important. Three statistical techniques are used to examine clustering--kernel smoothing, k-functions and raised incidence modeling. In addition, Site Catchment Analysis has been upgraded to explore terrain factors in a standardised, statistically robust fashion. The results are discussed under the headings: scale, terrain sensitivity, integration and tempo. The pattern is unusually clustered at many but not all scales. Important concentrations of ring ditches were sited in the previously unused foreshores of small glacial lakes. Further investigation of these foreshores produced an Late Bronze Age date for a larger, newly identified, burial monument type. I conclude that an iterative process, with no central design, but potentially based on kin groups, formed this concentration of sites. Further, the availability of well-drained soil is an important factor in the distribution of sites. There is a separation of domestic activities, burial, and other community rituals. However, this is not a 'ritual landscape'. In the Late Bronze Age this separation became more pronounced, possibly indicating increased social centralisation. These landscape changes may also indicate a changed role for the area in regional trading networks. The thesis contributes to an understanding of increased social complexity in a period of environmental change. It also indicates the value of quantitative landscape analysis in such discussions.

abstract: Doctor of Philosophy (PhD)


title: Finite Difference Analysis of Two-Span Continuous Composite Beams

contributor:
Robinson, H.
Civil Engineering

subject:
Civil Engineering
Civil Engineering

abstract: A method is developed for the analysis of two-span continuous composite beams in both elastic and inelastic ranges. A computer program is also formed as an integral part of this study. In order to verify the analysis and the computer program, three test beams were chosen as examples for computation. The computed results and the test results are in good agreement.

abstract: Master of Engineering (ME)


title: The comparative physiology of fathead minnows and rainbow trout: Insights into the tolerance of the two species to toxicants

contributor:
McDonald, D.G.
Biology

subject: Biology Biology

abstract: In this thesis the physiological systems of two unrelated freshwater fish with different tolerances to many toxicants were compared. Comparisons were made between fathead minnow (FHM) and rainbow trout (RBT) that were approximately 1.5 g. Differences between the two species were found in gill function and morphology, detoxification, and cellular resistance. The greater sensitivity of FHM than RBT to H+ ions was related to the fact that FHM appeared to regulate ions with less precision than RBT. There were significant linear relationships between whole body Na+ (r2 0.24) and Cl- (r2 0.33) and temperature as well as with Na+ uptake (r2 0.70) and temperature in FHM after up to 2 months acclimation. In contrast there were no significant relationships between these parameters and temperature in acclimated RBT. In addition, FHM did not up-regulate Na+ uptake even after they had lost up to 31% of whole body Na+ whereas there were 2-fold increases in RBT after whole body Na+ losses of 22%. The greater tolerance of FHM than RBT to ammonia and organic toxicants was partially attributed to lower gill uptake of these compounds. The activity rates of the ammonia detoxifying enzyme, glutamine synthetase were 1.7-fold higher in FHM than RBT. Fathead minnows also had 1.7-fold higher activity rates of the phase II biotransformation enzyme, glutathione-s-transferase, than RBT. Fathead minnows also tolerated higher tissue concentrations of ammonia, and monochlorobenzene than RBT. Finally, the sprint test was a useful measure of swim performance in both species. The rank order of individual sprint performance was reproducible in FHM (Spearman's rank coefficient (rs 0.95)) and RBT (r s 0.92), and sprint performance was impaired in FHM and RBT with acute exposure to ammonia. However, in FHM sprint performance declined when sprints were repeated at 24 h intervals whereas it was unaffected by this treatment in RBT. (Abstract shortened by UMI.)

abstract: Doctor of Philosophy (PhD)


title: Mechanisms of electrohydrodynamic (EHD) flow and heat transfer in horizontal convective boiling channels

contributor:
Shoukri, M.
Chang, J.S.
Mechanical Engineering

abstract: Experimental and numerical investigations have been conducted to study the mechanisms involved in the electrohydrodynamic (EHD) induced flow and heat transfer augmentation of two-phase systems. The experimental study involved tube-side boiling heat transfer of the environmentally friendly HFC-134a in a single-pass, counter-flow heat exchanger 1.5 m in length, 12.7 mm O.D., 10.92 mm I.D., with a 3.18 mm rod electrode. The electrode position was varied from a concentric geometry to an eccentric geometry offset vertically from the centerline by ±2.73 mm. The applied voltage was 0 kV to 8 kV DC or 0 kV to 24 kV peak to peak AC (60 Hz and 6.6 kHz). Experiments conducted for the eccentric geometry have provided evidence that through the establishment of the appropriate electric field distribution, a desired change of flow regime will occur to augment the heat transfer rates at significantly lower voltage levels and pressure drop penalties. These results were based on the interpretation of the finite element results of the electric field distribution for the arrangement under investigation. The experiment has shown that when the electrode was positioned eccentrically +2.73 mm from the centerline, a 160% enhancement in heat transfer coefficient was observed under the application of a 2 kV DC voltage while the pressure drop increase was only 1.2 fold. Through the evaluation of the dimensionless criterion for EHD induced effects, electric field distribution analysis, EHD flow regime transition criterion and local and overall parametric analysis, the present investigation has shown that the developed electric body forces lead to a reduction in the thermal boundary layer thickness, increased convection, enhanced boiling dynamics and interfacial instabilities that can result in a phase redistribution. The consequence of this flow regime transition is the potential for significantly enhanced heat transfer rates at the wall, with only minimal increases in pressure drop. (Abstract shortened by UMI.)

abstract: Doctor of Philosophy (PhD)


title: Neuropsychological Characteristics of Positive and Negative Symptoms of Schizophrenia: Implications for Cognitive Remediation

contributor:
Finlayson, J. M. Alan
Medical Sciences

subject:
Medicine and Health Sciences
Medicine and Health Sciences

abstract:
This study examines the relationship between neuropsychological functioning and positive versus negative symptoms of schizophrenia in order to test the hypothesis that negative symptoms are uniquely associated with cognitive deficits and attentional impairment. Forty chronic schizophrenics were subtyped on the basis of symptoms which were predominantly positive (n=10), predominantly negative (n=10), both positive and negative (n=10), or neither positive nor negative (n=10) and administered a battery of neuropsychological tests. The possibility that patterns of deficits among subtypes, if found, reflect lateralized or localized dysfunction was also examined.

Test data revealed that positive- and negative-symptom schizophrenics are equally impaired according to several global indices of neuropsychological functioning as well as on various measures of attention. These findings are inconsistant with the hypothesis that cognitive and attentional deficits are unique to negative-symptom schizophrenia as has been reported in the literature. Further analysis of deficit patterns revealed that positive-symptom schizophrenics, relative to the asymptomatic group, showed more marked deficits in verbal learning and memory whereas negative-symptom schizophrenics, based on identical comparisons, showed greater impairment on measures of fluency and productivity. No relation was observed between neuropsychological indicies of right versus left or, anterior versus posterior dysfunction and a patient's symptom status. In fact, the low correlation between psychiatric symptoms and neuropsychological performance was generally observed. Reconceptualization regarding defining characteristics of postive- and negative-symptom syndrome, particularly with respoect to assumptions about attention and cognition, is suggested.

The heterogeneity of neuropsychological deficits found among schizophrenics and their dissociation from the patients psychiatric presentation, stress the need for independent, individual assessment of cognitive functioning. Given that neuropsychological deficits, when identified, likely contribute to imparied social and occupational functioning, improvement in neuropsychological status may translate into improvement in these areas of everyday living. Preliminary results of an attempt at computer-based cognitive remediation in a seleted subset of schizophrenics are presented and a neuropsychological approach to psychiatric rehabilitation is proposed.

abstract: Doctor of Philosophy (PhD)


title: The production of shows in the cities of the Roman Empire: A study of the Latin epigraphic evidence

contributor:
Slater, W.J.
Classics

subject: Classics Classics

abstract: The "games"--scenic representations, chariot races, gladiatorial combats and athletic displays--played a fundamental role in the Roman world. A great deal has been said on the program and cost of such events, on their social function, on the role of the senatorial elite and emperors as providers of games. These issues, however, can be treated almost only with the city of Rome in view; there is very little in the sources that allows for a study along these lines at the level of the several thousands of cities of the Latin part of the Empire. The main reason for this is easy to identify: ancient authors show very little interest for municipal life and institutions. Our documentation on the production of games at the municipal level happens to be almost entirely composed of inscriptions written in a highly formalized language. This material can be deciphered only by bringing together and studying most or all relevant inscription on a given issue. So far, this has been done mostly according to categories of games; one team of scholars, for example, is presently republishing all inscriptions belonging to the world of the amphitheater: honorary inscriptions recording shows, gladiators' epitaphs, dedications of amphitheaters, & c. Though this approach is commendable in many respects, it has the disadvantage of concealing features shared by the games in general. Accordingly, this dissertation studies the games as displays of the benevolence of the wealthy towards their community. Two broad objectives are set forth: to improve our understanding of the language of the inscriptions so far as the games are concerned, and to determine under what circumstances a production of games is worthy of an epigraphic commemoration. The second of these two objectives is justified by the surprisingly small number of about five hundred relevant inscriptions from the Latin part of the Empire over a period of more than five centuries.

abstract: Doctor of Philosophy (PhD)


title: Effect of 17-beta-estradiol and gender on substrate metabolism in humans during exercise

contributor:
Tarnopolsky, Mark A.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: Gender differences in substrate utilization have been observed with females having higher lipid and less carbohydrate oxidation during endurance exercise. This thesis consists of a series of three studies conducted with the overall objective of advancing our understanding of gender differences in substrate metabolism and the mechanism behind these differences. The first and second studies investigated the effect of endurance training on whole-body substrate, glucose and glycerol utilization muscle enzyme adaptations in males and females. Carbohydrate utilization was lower following endurance training when tested at the same absolute exercise intensity. Glucose rate of appearance (Ra) and metabolic clearance rate (MCR) were lower following training. Females had a lower glucose MCR later in exercise as compared to males. Regardless of training status, females had a higher glycerol Ra as compared to males suggesting a greater whole-body lipolysis. Gender differences in lipid utilization were not accompanied by gender differences in maximal enzyme activities, which increased following endurance training for both genders. The third study investigated the effect of 17-β-estradiol on whole-body substrate, glucose and glycerol utilization during endurance exercise in males. The administration of 17-β-estradiol resulted in a lower MCR during exercise as compared to placebo. 17-β-estradiol also resulted in a higher plasma glucose concentration during exercise, but had no effect on substrate oxidation, glycerol turnover or plasma glycerol and FFA concentrations at rest or during endurance exercise. It can be concluded that females have a higher whole-body lipolysis and oxidize a greater proportion of fat. The glucose kinetic data from the training study together with the data from the 17-β-estradiol study suggested that females used less hepatic glucose during endurance exercise. Although alterations in glucose kinetics were found following the administration of 17-β-estradiol to males further research is required to unravel the mechanism(s) behind the gender difference in substrate metabolism.

abstract: Doctor of Philosophy (PhD)


title: Wetland Classification and Environmental Monitoring in the Peace-Athabasca Delta using LANDSAT Digital Data

contributor:
Howarth, P.J.
Geography

subject: Geography Geography

abstract:
Through the use of LANDSAT digital date and automated image classification techniques, habitats of the Peace-Athabasca Delta region in northeastern Alberta were classified, and mapped, a number of change detection techniques evaluated, and the potential of using LANDSAT digital data in a long-term monitoring program assessed.

The General Electric Image 100 Multispectral Image Analysis system was used to conduct a supervised classification for a 1200 Km² test site centered on Mamawi Lake at the east end of the Delta complex. To provide optimum opportunity for detecting change and for testing the classification of habitats under differing conditions, two images, one with normal water levels (August 1, 1976) and one with above normal water levels (August 26, 1973), were selected for analysis. A total of eight habitats was identified for the 1976 data and seven for the 1973 date.

Classification accuracy of the 1976 habitats was considered excellent when compared with available ground reference data. Although ground reference data were not available for 1973, classification results are considered good. Spatial filtering of the classified scenes was found to improve the visual quality of the images, although only marginal improvements in classification accuracy resulted.

The classified scenes were found to be useful in delineating major topographic subdivisions within the Delta. These subdivisions can be used to identify areas most susceptible to change. Using an image registration technique, the 1973 and 1976 scenes were overlayed and two change detection analyses carried out. These were ratioing and post-classification change detection. Ratioing was found to be relatively fast and simple method for determining the areal extent of flooding and areas of major vegetation change. Post classification change detection was carried out for the entire study ares as well as 1/2 and 1/8 areas. The technique was found to be useful in identifying the nature of change, although further research is required before an evaluation of the absolute values generated in the analyses can be fully assessed.

It is anticipated that when extrapolated over the entire 37,500 Km² area of the Delta, the use of digital LANDSAT data will provide a relatively low cost and yet effective means of maintaining a current habitat map of the region, as well as providing an effective method for detecting and monitoring environmental change.

abstract: Master of Science (MS)


title: Stochastic Operation Management Model for a Multi-Reservoir Inter-Basin Water Resource System

contributor:
Woo, Ming-Ko
Civil Engineering

subject:
Civil Engineering
Civil Engineering

abstract:
The discrepancy between the quantity and regime of water consumption and natural river flow usually gives rise to the need to create a multi-reservoir inter-basin water resource system to redistribute the river flow temporally and spatially. As the economic value of water increases and inexpensive sources of water supply diminish, the development of an optimal operation management model becomes more and more important.

In this thesis, a stochastic operation management model composing of two integrated models of stochastic multi-site flow generation model and deterministic Dynamic Programming optimization model is developed to determine the optimal operation of a multi-reservoir inter-basin water resource system. The stochastic multi-site flow generation model is used to generate synthetic now series as input to the optimization model. In this model. the stochastic nature of historical flows to reservoirs, i.e. auto-correlation and cross-correlation, is explicitly considered. The deterministic Dynamic Programming optimization model is developed to determine the optimum operation policies for each of the many synthetic flow series through application of the optimization model to the multi-reservoir inter-basin water resource system. The approach of separating these two models will overcome the curse of dimensionality encountered in existing DP optimization models while allowing the stochastic nature of inflows to be incorporated into the optimization process and resulting optimum operation policies.

The real case study approach, selection criteria and description of case study area, Lar-Kalan-Latian water resource system in Tehran, Iran as a multireservoir inter-basin water resource system is discussed. The superiority of a real case study in comparison with a hypothetical or abstract one is demonstrated.

A comprehensive review and identification of stochastic multi-site now generation models and discussion of available flow generation computer programs are presented. The statistical analysis of historical monthly and annual now data of the case study, setting up of HEC-4 program as direct method and SPIGOT program as disaggregation technique, and generation and verification of synthetic monthly and annual flow series for the case study are discussed. The comparison of HEC-4 and SPIGOT synthetic flow series with historical data shows the effectiveness of SPIGOT program against HEC-4, even for the short historical flow input data.

A detailed review and discussion of the Dynamic Programming techniques and development of deterministic DP optimization model for the multi-reservoir inter-basin water resource system is carried out. The generation, comparison, statistical analysis, and reliability characteristics of optimum monthly operation polices determine by applying the developed DP optimization model is discussed. The comparison of optimum operation with historical operation demonstrates the usefulness and improvement of optimum operation upon historical operation. It is further concluded that the DP optimization model is not sensitive to the type of stochastic flow generation model used to generate synthetic flows. Finally, the development of optimum operation reliability characteristics demonstrates the application ofstochastic operation management model in planning and operation of multi-reservoir inter-basin water resource system.

abstract: Doctor of Philosophy (PhD)


title: Field officer discretion in the implementation process: Immigration policy in Canada, Quebec and the United States

contributor:
Carroll, Barbara Wake
Political Science

subject:
Political Science
Political Science

abstract: Immigration is a policy area that is becoming increasingly relevant among researchers in international relations and comparative politics as they address the difficulty advanced industrialized countries have in controlling their borders. Most research on immigration policy examines this issue by focusing on external and macro level internal factors which influence policy choices and policy outcomes. While these explanations are useful, they neglect the manner into which policy choices are translated at the implementation stage by officers in the field. This dissertation suggests that field officers have a great impact on policies and on their outcomes as they are the ones who are responsible for interpreting and implementing the policies designed by policy makers. It is argued that a micro approach utilizing interactive theories of public policy and public administration which takes into consideration the discretion of the individual civil servant is a useful supplement to macro and meso theories about immigration. This conclusion is reached by a study of two countries (Canada and the United States) and one province (Quebec). The dissertation considers the external selection process and examines the circumstances under which field level discretion is exercised. Its conclusion is that Canadian officials operate with a higher level of discretion than their US counterparts, while Quebec agents enjoy an even higher level of discretion. These differences, it is suggested, are explained by variations in political institutions, organizational structure, organizational resources and the degree of importance attached to some overriding goal--in this case the concern for social and cultural integration in Quebec.

abstract: Doctor of Philosophy (PhD)


title: Repulsive signaling from the Drosophila midline requires slit function: Repellent signaling through Robo1 requires the Slit LRR

contributor:
Jacobs, J.R.
Biology

subject: Biology Biology

abstract: To establish the bilateral symmetry present in the midline of the Drosophila CNS the midline cells must generate a repulsive barrier that divides both halves of the embryo. Here we report the identification and characterization of the midline repellent ligand Slit. Slit is expressed and secreted from the MG where it signals to growth cones pathfinding along the lateral border of the midline. In embryos of severe slit mutants all CNS axons fuse at the midline. slit transgenes expressed at the midline functionally rescue the slit mutant phenotype. Furthermore, ectopic expression of slit transgenes repels CNS axons away from regions of transgene expression. Analysis of point mutations in the slit locus suggest that the LRR motifs found in Slit protein are required for Slit's repulsive function in the midline cells. Additionally, in vivo expression of truncated slit transgenes containing only the LRR was sufficient to partially restore Slit repellent signaling to the midline and generate ectopic signaling phenotypes. slit transgenes lacking the LRR domains have no repellent activity. Embryos transheterozygous for slit and robo1 have pathfinding errors that are not observed in embryos heterozygous for either allele, a classic indication of a genetic interaction between two genes. Additionally, in vitro binding assays demonstrate that Slit binds Robo1 and more specifically that this binding requires the complete Slit LRR domain. These data show that Slit is midline ligand that binds the repellent receptor Robo1 in order to establish the midline barrier formed between opposite halves of the Drosophila embryo.

abstract: Doctor of Philosophy (PhD)


title: Balancing protection and activation: Silyl ethers and dicobalt complexes as controlling elements in organic synthesis

contributor:
Brook, Michael A.
Chemistry

subject: Chemistry Chemistry

abstract: The tris(trimethylsilyl)silyl (sisyl) ether is photolabile, and possesses the potential to be used as a hydroxyl protecting group which can be photolytically cleaved selectively, in the presence of other silyl ethers. In order to compare its hydrolytic stability with that of a t-butyldimethylsilyl (TBS) ether, the rates of acidic hydrolysis of a series of sisyl and TBS ethers were determined under pseudo-first-order conditions. The sisyl ethers were found to be more hydrolytically stable in CDCl3 containing p -TsOH·H 2 O, but less hydrolytically stable in a AcOH/THF/H2 O solvent mixture. The hydrolysis studies were extended to the corresponding series of alkoxyallyl- t -butylmethylsilanes, which were determined to be more hydrolytically stable than either the sisyl or the TBS ethers. The ability of the alkoxyallyl-t-butylmethylsilanes to function as both allylsilanes (undergoing silicon-carbon bond cleavage), and alkoxysilanes (undergoing silicon-oxygen bond cleavage), was examined under conditions that could lead to both processes. In the presence of Brønsted acids, silicon-oxygen bond cleavage occurred exclusively. Electrophilic substitution of the allyl group was only observed in the presence of the very sterically hindered triphenylcarbenium ion. Allylsilanes were also originally envisioned as ideal nucleophilic partners for the development of a method of forming carbon-carbon bonds at the propargylic carbon atom of dicobalt-complexed acetylenic aldehydes or ketones, diastereoselectively. Allyl transfer onto racemic mixtures of chiral dicobalt pentacarbonyl(triarylphosphine)-complexed acetylenic aldehydes, leading to the formation of the hexa-1,5-enyne system, was accomplished with modest diastereoselectivity.

abstract: Doctor of Philosophy (PhD)


title: Generic mechanistic modeling for multi-axis machining

contributor:
Elbestawi, M. A.
Mechanical Engineering

abstract: A generic mechanistic approach for simulating multi axis machining of complex sculptured surfaces is presented. A generalized approach is developed for representing an arbitrary cutting edge design, and the local surface topology of a complex sculptured surface. A NURBS curve is used to represent the cutting edge profile. The local surface topology of the part is defined as those surfaces generated by previous tool paths in the vicinity of the current tool position. The local surface topology of the part is represented without using a computationally expensive CAD system. A systematic prediction technique is then developed to determine the instantaneous tool/part interaction during machining. The methodology employed here determines cutting edge in-cut segments by determining the intersection between the NURBS curve representation of the cutting edge and the defined local surface topology. These in-cut segments are then utilized as integration limits for a comprehensive force modeling methodology. A systematic model calibration procedure that incorporates the effects of varying cutting edge geometry, cutting speeds, and feed rates is developed. Experimental results are presented for the calibration procedure. Model verification tests were conducted with these cutting force coefficients. These tests demonstrate that the predicted forces are within 5% of experimentally measured forces. An enhanced approach for dynamic mechanistic modeling for multi-axis machining is developed. The dynamic process simulation methodology is presented as a continuous solution for complex sculptured surface machining. The simulation results demonstrate how the continuous dynamic process simulation methodology is capable of predicting the cutting force and tool deflection for variable tool/workpiece immersions that occur during complex sculptured surface machining operations. The generic simulation approach for multi-axis machining has been demonstrated as a process optimization tool. Feed scheduling was used to demonstrate the process optimization for multi-axis machining. A feed scheduling methodology for multi-axis machining was developed. A case study for process optimization of machining an airfoil-like surface was used for demonstration. Based on the predicted instantaneous chip load and/or a specified force constraint, feed rate scheduling was utilized to increase metal removal rate. The feed rate scheduling implement at ion results in a 30% reduction in machining time for the airfoil-like surface without any sacrifice in the surface quality or part geometry. (Abstract shortened by UMI.)

abstract: Doctor of Philosophy (PhD)


title: Development of an accelerator based system for in vivo neutron activation analysis measurements of manganese in humans

contributor:
McNeill, Fiona E.
Physics and Astronomy

subject:
Astrophysics and Astronomy
Physics
Astrophysics and Astronomy

abstract: Manganese is required by the human body, but as with many heavy elements, in large amounts it can be toxic, producing a neurological disorder similar to that of Parkinson's Disease. The primary industrial uses of the element are for the manufacturing of steel and alkali batteries. Environmental exposure may occur via drinking water or exhaust emissions from vehicles using gasoline with the manganese containing compound MMT as an antiknock agent (MMT has been approved for use in both Canada and the United States). Preclinical symptoms of toxicity have recently been detected in individuals occupationally exposed to airborne manganese at levels below the present threshold limit value set by the EPA. Evidence also suggests that early detection of manganese toxicity is crucial since once the symptoms have developed past a certain point, the syndrome will continue to progress even if manganese exposure ceases. The development of a system for in vivo neutron activation analysis (IVNAA) measurement of manganese levels was investigated, with the goal being to have a means of monitoring both over exposed and manganese deficient populations. The McMaster KN-accelerator was used to provide low-energy neutrons, activation within an irradiation site occurred via the 55 Mn(n,γ) 56 Mn capture reaction, and the 847 keV γ-rays emitted when 56 Mn decayed were measured using one or more Nal(TI) detectors. The present data regarding manganese metabolism and storage within the body are limited, and it is unclear what the optimal measurement site would be to provide a suitable biomarker of past exposure. Therefore the feasibility of IVNAA measurements in three sites was examined--the liver, brain and hand bones. Calibration curves were derived, minimum detectable limits determined and resulting doses calculated for each site (experimentally in the case of the liver and hand bones, and through computer simulations for the brain). Detailed analytical calculations of the 7 Li(p,n) 7 Be reaction, used to produce neutrons by the KN, were conducted to determine neutron spectral information, angular distributions and yields. These data were used as input for the transport code MCNP, and computer simulations of experimental conditions were performed. The simulations consistently overestimate experiment measurements by a constant factor, and possible reasons for this discrepancy are discussed. It has been concluded that IVNAA measurements of the brain would only provide limited information, however, measurement of both the liver and hand bone should be possible. It is recommended that preliminary in vivo measurements be pursued for the hand, as metabolic data suggest that bone may be a long term storage site for manganese.

abstract: Doctor of Philosophy (PhD)


title: Determination of the optical properties of two-layer turbid media from spatially resolved reflectance measurements in the frequency domain

contributor:
Patterson, M.S.
Medical Physics

subject: medical physics

abstract: Quantification of the optical properties of superficial biological tissue (e.g. skin on muscle) from spatially resolved reflectance measurements can yield important physiological information. Some examples include the non-invasive measurement of chemotherapy drugs or exogenous chromophores used for photodynamic cancer treatment and the assessment of hemoglobin oxygenation in tissue. Superficial tissue is a multilayered structure with each component having different macroscopic absorption and scattering coefficients, as well as different vascularization and exogenous chromophore pharmacokinetics. A layered model of photon transport is therefore required to match theoretical predictions with experimental measurements. Once a photon transport model is developed, it defines the forward calculation used in the inverse problem of determining the set of tissue optical properties that gives the best fit to experimental data. In the present work the frequency domain (FD) method is employed to probe a two-layer turbid medium. The goal is to improve quantification of superficial tissue optical properties relative to current methods assuming tissue homogeneity. Chapter 2 introduces simulated annealing as a robust method of exploring the limits of a two-layer pure diffusion model in determining the optical properties of a two-layer turbid medium. The inadequacies of pure diffusive transport lead to inaccurate optical property estimates for the top layer. To improve on these estimates a hybrid Monte Carlo (MC)--diffusion model for FD photon transport was developed and presented in Chapter 3. The hybrid model was shown to accurately model MC simulated reflectance data for all optical properties in the physiological range. In Chapter 4 an efficient hybrid simplex--simulated annealing global optimization algorithm was introduced to demonstrate that the hybrid transport model can, in principle, accurately determine all optical properties of a two-layer turbid medium. The practical feasibility of the method was tested with high accuracy FD experimental measurements. Some preliminary results and future directions towards the in vivo implementation of the method are discussed.

abstract: Doctor of Philosophy (PhD)


title: Some Families of Quaternion Fields and the Second Chinburg Conjecture

contributor:
Snaith, V.P.
Mathematics

subject: Mathematics Mathematics

abstract:
Let N/K be a finite Galois extension of number fields with Galois group G. The second Chinburg conjecture asserts the equivalence in the locally free class group CL(Z[G]) of the classes corresponding to two arithmetic invariants attached to the extension, namely the Frōhlich-Cassou-Noguès class Wɴ/k and the second Chinburg invariant Ω(ɴ/k,2). Frōhlich originally formulated a conjectural equivalence of the class Wɴ/k and the class [Oɴ] determined by the ring of integers in N, and this was subsequently verified by M. Taylor. The second Chinburg invariant Ω(N/K,2) may be interpreted as a generalisation of the class [Oɴ] to wild extensions, and Chinburg showed that Frōhlich's conjecture for tame extensions implied Chinburg's conjecture for tame extensions.

More generally, the second Chinburg conjecture has been verified when G is absolutely abelian of odd conductor (C. Greither) and for several infinite families of wildly ramified quaternion fields (S. Kim). When N/K is wildly ramified and G is nonabelian, little further evidence for the conjecture is known.

In this thesis we consider some families of extensions N/Q with G ≅ Q₈, the quaternion group of order 8, in which the prime 2 is totally ramified. In particular we consider those quatermon extensions containing a biquadratic subfield of the form Q(√a, √b), where a ≡ 2 mod 16 and b ≡ mod 8. We verify the second Chinburg conjecture for all such extensions.

We begin by localizing at the prime 2 and make use of a cohomological classification of a large class of cohomologically trivial 2-primary Z[Q₈]-modules to explicitly compute the local second Chinburg invariant. Globally, we construct a projective Z[Q₈]-module, X, that lies inside ON, the ring of integers of N. We then work with Frōhlich's Hom-description of the class group and show that, in fact, [X] = Wɴ/Q in CL(Z[Q]), where [X] denotes the class of X. Combining this with the local information, and using congruence methods, we conclude that in CL(Z[Q₈]),

Ω(ɴ/Q,2) = Wɴ/Q,

i.e., the second Chinburg conjecture holds for these extensions.

Combining this result with work of S. Kim, V. Snaith and M. Tran, this establishes the second Chinburg conjecture for all extensions ɴ/Q having Galois group G ≅ Q₈.

abstract: Doctor of Philosophy (PhD)


title: Blind adaptive cyclic filtering and beamforming algorithms

contributor:
Wong, Kon Max
Electrical and Computer Engineering

abstract: In a multi-user communication system such as the wireline or wireless communication systems, a commonly encountered problem is the extraction of the desired signal from Co-Channel Interference (CCI) and Adjacent Channel Interference (ACI). To combat the CCI and ACI, the conventional filtering techniques are unable to carry out the job. The optimum FREquency-SHift (FRESH) filtering technique proposed by W. A. Gardner enables us to suppress spectrally overlapped signals by using the cyclostationarity of the signals. However, to design the optimum FRESH filter, we must have the statistical knowledge of the desired signal or a training signal which, in practice, are not often available. This thesis proposes a blind adaptive FRESH filtering algorithm which does not need a training signal to extract the desired signal from spectrally overlapping interference. We call this new technique Blind Adaptive (BA)-FRESH filtering. Comparing the BA-FRESH filter with the FRESH filter with a training signal which is called Trained Adaptive FRESH (TA-FRESH) filter, it has been proved that BA-FRESH and TA-FRESH have same performances when the data length is infinite. On the other hand, various cyclic beamforming techniques such as the spectral Self-COherence REstoral (SCORE), the Cyclic Adaptive Beamforming (CAB), the Constrained Cyclic Adaptive Beamforming (C-CAB) and the Robust Cyclic Adaptive Beamforming (R-CAB) algorithms can be used to combat CCI and ACI efficiently. However, when the desired signal and the interferences are very closely spaced in arrival directions, system performance improvement using these cyclic beamforming alone is limited because the beamformers are just spatial filters. By combining the spatial beamforming with the temporal FRESH filtering, a large system performance improvement may be achieved due to the full utilization of the signal information in both time and space domains. A Blind Adaptive Space-Time (BLAST) algorithm is proposed in this thesis. The BLAST algorithm is a blind adaptive time varying space-time filter. The BLAST algorithm can be viewed as the expansion of the BA-FRESH filtering algorithm to the space-time domain. Comparing the BLAST filter with the space-time filter with a training signal which is called Trained Adaptive Space-Time (TAST) filter, it has been proved that BLAST and TAST have same performances when the data length is infinite. When the data length is finite, there are performance differences between BLAST and TAST. Convergence of the BLAST and TAST filter coefficients, the finite sample output signal to interference plus noise ratio (SINR), and the finite sample output mean square error (MSE) are analyzed. (Abstract shortened by UMI.)

abstract: Doctor of Philosophy (PhD)


title: BEHAVIOUR CHARACTERISTICS OF FACE SHELL MORTARED BLOCK MASONRY UNDER AXIAL COMPRESSION

contributor:
Drysdale, R.G.
Civil Engineering

subject:
Civil Engineering
Engineering
Civil Engineering

abstract:
Although face shell mortared blockwork constitutes the main construction practice in North America, its behaviour characteristics are relatively undefined and has traditionally been assumed to behave in asimilar manner to brick and solid block masonry. Only recently has it been reported that face shell mortared concrete blockwork failed differently and the failure theories developed for these cases may not be applicable to face shell mortared blockwork. It is the main objective of this investigation to provide a better understanding of behaviour of face shell mortared blockwork and to arrive at the reasonably accurate measure of its strength under axial compression.

A total of 461 concrete block prisms incorporating a broad base of material properties and sources (29 block plants) were tested in axial compression normal to bed joints. In addition over 1400 auxiliary block compression and tension tests and mortar tests were carried out. The experimental investigation included a comprehensive study of the properties of the constituent materials, re-evaluation of current test methods for measuring the compressive strength of the blockwork, detailed deformation monitoring of the behaviour, parametric study of the variables affecting the strength of face shell mortared blockwork, comparison to other types of concrete masonry construction and quantitative assessment of specified strengths for hollow concrete blockwork.

Regardless of the block size or shape,cracking of the webs is the expected failure pattern in face shell mortared blockwork and failure criteria attributing the dilation of mortar as the cause of failure are not applicable in this case. Since much reserve strength is available after initial observation of web cracking, models which predict cracking should not necessarily be expected to predict ultimate strength. Although the block's compressive strength can be related to blockwork compressive strength, a strong relationship existed with the block tensile strength. While web cracking in face shell mortared blockwork initiates in a mechanism independent of mortar, it cannot be concluded that the ultimate strength is independent of the type or strength of mortar. Employing 2-course prisms for measurement of blockwork compressive strength would result in an unrepresentative failure and overestimated strength. Currently employed relationship for determining the modulus of elasticity of concrete block masonry is clearly an overestimation.

abstract: Master of Engineering (ME)