title: Prenatal Diagnosis and Selective Therapeutic Abortion in the Prevention of Down's Syndrome - An Evaluation Emphasizing Medical & Economic Issues

contributor:
Walker, H.D.
Health Care Research

subject:
Health Services Research
Public Health
Health Services Research

abstract:
The organization of Health Care in Canada is such that many of the crucial decisions affecting the health of our population are made by politicians whose previous experience has not been in the health sector. This thesis is an attempt to present some of the medical and economic issues related to the prenatal diagnosis of disease in a form which can be readily understood by individuals who are neither physicians nor economists.

The technology responsible for prenatal diagnosis has developed very rapidly over the past few years and now the need for an evaluation of the potential role of these techniques in, the prevention of serious genetic disease is widely recognized. This thesis evaluates the effects of prenatal diagnosis on Down's Syndrome, which is the most common serious genetic disease identified in this way, but many of the findings can be applied to other serious genetic disorders.

The extent of the problem presented by Down's Syndrome was evaluated by reviewing the literature related to the medical, developmental and epidemiological characteristics of the disease. The findings indicate that this serious disorder is fundamentally irreversible despite the major effects that are made to provide special medical, educational and residential facilities for affected individuals. In addition, Down's Syndrome is a relatively common disorder and it is estimated that there are approximately 130 affected infants born each year and that there are 9,000 affected individuals in Ontario at the present time. The specific cause of the disorder remains unknown although the increasing incidence of affected infants with advancing maternal age is well recognized. The new techniques of prenatal diagnosis and selective abortion offer the only effective method of preventing the birth of these seriously and irreversibly handicapped infants.

The procedures involved in obtaining a prenatal diagnosis are reviewed in some detail and it is concluded that the techniques are both medically safe and diagnostically reliable when provided by experienced personnel. Parents are offered a therapeutic abortion when a defective fetus is identified and although a mid-trimester abortion is associated with some morbidity and mortality, the risks are not greater than those associated with a full-term delivery. These findings suggest that prenatal diagnosis could be made available to all those parents who would benefit from health information of this sort without imposing unacceptable health hazards.

A major section of this thesis devoted to the evaluation of the economic effects of a program proving prenatal diagnosis, using the technique of cost-benefit analysis. The implications of several diagnostic and patient management policies are examined and the results indicate that prenatal diagnosis should be offered to all women aged 35 years or more. The use of less conservative estimates would suggest that the service could be extended to younger women and still remain economically feasible.

The final conclusion, based on medical economic and administrative considerations is that the existing prenatal diagnosis programs should be expanded to provide this service to all women aged 35 or over as soon as possible.

abstract: Master of Science (MS)


title: Some Aspects of Goodness-of-Fit Tests in the Presence of Unknown Parameters

contributor:
Stephens, M.A.
Applied Mathematics

subject:
Applied Mathematics
Applied Mathematics

abstract:
Goodness-of-fit testing of simple hypotheses has a long, well known history. When the Null Hypothesis specifies only the form of the Null Cumulative Distribution Function (CDF), with values for one or more parameters unspecified, the problem is not so clear cut. This project examines several methods of testing fit in the presence of unknown parameters. The methods, briefly described below, are all based on the Empirical Distribution Function (EDF).

(1) The unknown parameters are estimated from the sample. Modified EDF statistics using these sample estimates, are computed, and compared to the significance points which have been obtained by computer simulation.

(2) The unknown parameters are estimated from the sample. Transformations are applied to the observations to obtain transformed variates which, under the Null Hypothesis, are distributed as dependent uniform variates. These transforms are tested for uniformity by the EDF statistics.

(3) A series of transformations is applied to the data to obtain transformed variates which under the Null Hypothesis follow a completely specified Distribution Function; the nuisance parameters have been eliminated. This new, simple hypothesis is then tested by the EDF statistics.

(4) For various parameter values throughout the parameter space, the EDF statistics are computed. A region in the parameter space for acceptance of the corresponding simple hypotheses is determined.

abstract: Master of Science (MS)


title: Bandwidth Minimization for Sparse Matrices

contributor:
Chakravarti, P.C.
Computation

subject:
Computational Engineering
Computational Engineering

abstract: A short survey of recent developments in sparse matrix techniques is presented in this project. One of the problems in this area is concerned with bandwidth reduction. Several algorithms for finding symmetric row and column permutations for a given sparse symmetric matrix, such that the resulting matrix has minimum bandwidth, are discussed. A few modified algorithms yielding a better bandwidth reduction are also presented. Six well known Example problems are utilized to illustrate the work.

abstract: Master of Science (MS)


title: The Mechanical Properties of High Strength Low Alloy Steels

contributor:
Embury, J.D.
Metallurgy and Materials Science

subject:
Materials Science and Engineering
Metallurgy
Materials Science and Engineering

abstract: The relationships between the mechanical properties, fracture and forming characteristics and the microstructural features has been investigated in commercially available HSLA steels. In addition, attention has been focussed on the behaviour of these materials subjected to a reverse straining, as a very important characteristic for pipeline applications.

abstract: Master of Engineering (ME)


title: The Simulation of the Behavior of a Student-Created Operating System using GPSS

contributor:
Rink, R.A.
Kenworthy, D.J.
Computation

subject:
Computer Engineering
Computer Engineering

abstract: While operating system concepts are taught to students in undergraduate programs in Computer Science, a student project involving the development of an operating system creates a difficult situation due to time and financial considerations. Using GPSS to simulate the behavior of a student-treated operating system can reduce these problems and serve as an effective learning device. Many features and concepts can be simulated that might otherwise be ignored in a student project. An implementation of a student-created operating system is discussed. Statistics collected from the GPSS simulated model are used to operating system.

abstract: Master of Science (MS)


title: Decision support for suburban retrofitting

contributor:
Baetz, Brian W.
Civil Engineering

subject:
Civil Engineering
Civil Engineering

abstract: Despite its popularity over the past 55 years, suburban sprawl development is widely criticized in the planning literature. Suburban sprawl is automobile dependent, socially segregating, and overly consumptive of raw materials, land and energy. Typically constructed at densities that do not support effective transit systems, suburban sprawl is often viewed as an unsustainable development form. Interest in urban sustainability evolved following the publication of Our Common Future in 1987, such that many communities now have vision statements and objectives for achieving sustainable community designs. There also has been a revival of neo-traditional planning concepts for the design and construction of new neighbourhoods to resemble those constructed prior to WWII (a period of lesser automobile dependence). Despite these efforts, there are many existing suburban areas surrounding cities in North America that need retrofitting, so that they may become increasingly sustainable. This dissertation develops a conceptual model providing decision support for suburban retrofitting, with the intent that the retrofitted suburbs exhibit a greater degree of sustainability than existing conventional suburban developments. This model, applicable at the neighbourhood scale, represents a departure from current sustainable community planning which is more focussed on greenfield developments. The conceptual model provides retrofitting methodologies for nine aspects of conventional suburban development, including those for increased density, added commerce and employment components, and reduced water, energy and material consumption. Automobile dependence is, in part, addressed by enhancing pedestrian networks and the implementation of neighbourhood traffic calming measures. Three prototype decision support tools have been created to assist a municipal planner or engineer in retrofitting a conventional suburban neighbourhood. These tools could be used at various stages within the planning process: (1) during the development or review of a community's Official Plan; (2) at the time of major street or utility reconstruction (to coincide with traffic calming installation); or (3) when more modest alterations to the neighbourhood are being considered (e.g., addition of street trees or pedestrian paths). The decision support tools can be used independently to model specific retrofitting aspects of neighbourhoods that may be of current interest to planners (e.g., traffic calming). When integrated with one another, they could be used to develop strategies for how a city might incorporate future population growth within existing built up areas, thereby maintaining a strict urban growth boundary. The prototype decision support tools are compiled for use in ArcView GIS and allow the user to generate and evaluate retrofitting scenarios for pedestrian connectivity, neighbourhood traffic calming and neighbourhood greening. GIS is the most suitable framework for these tools as it is a primary component in neighbourhood and regional planning processes. Sample applications are provided for case study neighbourhoods in Hamilton, Ontario to demonstrate the use of these tools, particularly to illustrate the key benefits one can achieve by retrofitting conventional suburban areas.

abstract: Doctor of Philosophy (PhD)


title: Simultaneous correction for scatter and attentuation in positron emission tomography using statistical image reconstruction methods

contributor:
Nahmias, Claude
Physics and Astronomy

subject:
Astrophysics and Astronomy
Physics
Astrophysics and Astronomy

abstract: In this work, a method to perform simultaneous scatter and attenuation correction for PET is developed within the context of statistical image reconstruction methods. The principles are demonstrated using both numerical simulations of artificially constructed scatter distributions and Monte Carlo studies of phantoms, showing the viability of this method in practice. In addition, a new transmission scan protocol is defined which is necessary to collect the required data in order to perform the corrections. The method has several distinct advantages over traditional filtered back-projection techniques. These include treating scatter and attenuation simultaneously so that a correction can be made during image reconstruction, leading to a one-step method; guaranteed non-negativity of the reconstructed pixel intensity values; predictable noise propagation; and improved counting performance by 65% resulting in an increased signal-to-noise ratio (on the order of 28%), achieved using non-windowed acquisition. Noise Equivalent Count rate analysis indicates that for a nominal clinical activity concentration of 37 kBq/cc (1 μCi/cc), a three-fold improvement in scanner performance can be realized for a standard acquisition window, compared to an uncorrected image and a five-fold improvement is achievable using an extended acquisition window.

abstract: Doctor of Philosophy (PhD)


title: Axonal growth, neuronal damage and epileptogenesis

contributor:
Racine, R.J.
Psychology

subject: Psychology Psychology

abstract: Neuronal damage and synaptic reorganization are two common neuropathological changes repeatedly detected in human epilepsy patients and animal models of epilepsy. To date, the relationship between cell loss, axonal growth, and epileptogenesis remains unclear. However, it is proposed that neuronal damage within the hilar area and mossy fiber sprouting alter the balance of excitation and inhibition within the epileptic brain, and contribute to the development of seizures. The axonal sprouting is suggested to be triggered by either cell loss or by excessive neuronal activity, or both. In the present study, we tested epileptogenesis and seizure-related morphological changes in several rat strains, including the Wistar strain and Long-Evans hooded strains, and the kindling-prone (FAST) and kindling-resistant strains (SLOW) created at McMaster University. These strains were tested using both KA- and pilocarpine-induced status epilepticus models. Although the Wistar and the Long-Evans hooded strains respond similarly to KA or pilocarpine-induced SE, we found that the Wistar rat strain showed a reliable neuronal loss and more severe neuronal growth, while the Long-Evans strain showed no detectable neuron damage and moderate axonal sprouting. The mossy fiber system was also significantly different between the FAST and the SLOW strains, and responded differently to seizure activity. This evidence suggests that genetic factors might be important for the induction of seizure-related morphological changes. In addition to the strain differences in seizure development, axonal growth and neuronal loss, it has been shown that epilepsy and synaptic reorganization can be developed independently of gross neuronal loss within the hilar area. Thus, it is clear that neuronal damage within the hilus is neither a crucial prerequisite, nor a necessary consequence of epileptogenesis or axonal growth. Our results favour the postulate that epilepsy-related axonal growth is at least partly triggered by excessive neuronal activity and contributes to the development of seizures. We have also tested the modulation of axonal growth and kindling development by infusing factors that affect axonal patterning and pathway finding during neuronal development, such as Neurotrophin-3 (NT-3), or axonal guidance molecules, the Eph receptors and the ephrins, into adult CNS. Continuous infusion of NT-3, or agents that affect the function of EphA receptors and ephrins, alters kindling epileptogenesis and the extent and pattern of mossy fiber sprouting in adult rats. Thus, we have shown that such factors preserve their functions into adulthood, and regulate activity-dependent axonal growth in the kindling model. Agents that affect the function of these molecules dramatically alter both kindling induction and mossy fiber sprouting. Therefore, it is likely that neurotrophic factors and axonal guidance molecules preserve their function into adulthood, modulating neuronal plasticity, epileptogenesis and synaptic reorganization in adult CNS.

abstract: Doctor of Philosophy (PhD)


title: Metabolism of Testosterone, Progesterone and Androstenedione in the Liver, Testes, Hypothalamus and Cortex of Normal and Testicular Feminized (Tfm) Mice

contributor: Medical Sciences (Growth and Development)

subject:
Medical Sciences
Medical Sciences

abstract:
The in vitro metabolism of testosterone, progesterone and androstenedione was studied in liver, testes, hypothalamus and cortex incubations of normal BALB/c♂, BALB/c♀ and a number of sex-mutant mice carrying the testicular feminization (Tfm) and sex-reversal (sxr) genes.

The metabolism of testosterone was studied in liver homogenates of BALB/c♂ , Tfm (o⁺)⚥ and Tfm (oʰᵛ)⚥. Androstenedione was identified as the major metabolite of testosterone, in all incubations, indicating the presence of 17β-hydroxysteroid dehydrogenase activity. Comparison of the percentage conversions of testosterone to androstenedione suggested that of the three genotypes studied, the activity of 17β-hydroxysteroid dehydrogenase was lowest in the Tfm (oʰᵛ) liver.

Similarly, the metabolism of testosterone and progesterone was studied by double-labelled tracer experiments using testes minces from BALB/c⚥ , Tfm (o⁺)⚥ and Tfm (oʰᵛ)⚥ mice. The conversion of progesterone to testosterone was greatest in BALB/c♂ incubations and least in the Tfm (o⁺) incubations. These data suggest that the relative activities of the 17-ketoreductase for the conversion of androstenedione to testosterone are in the order: BALB/c♂ > Tfm (oʰᵛ) ⚥ > Tfm (o⁺).

Progesterone metabolism was studied in testis incubations of normal male (BALB/c♂), testicular-feminized, sex-reversed (Tfm+(oʰᵛ) Blo/+++, sxr/+ ♂) and sex-reversed (+Ta++/+++, sxr/+♂) mice. Comparison of the amounts of androstenedione and testosterone formed from P suggests that differences are present in the relative activity of the testis 3-ketoreductase. The relative activity is in the order BALB/c♂ > +Ta++/+++, sxr♂ > Tfm+(oʰᵛ) Blo/+++, sxr♂.

The metabolism of androstenedione was also studied in testes incubation of Tfm (o⁺)⚥ and Tfm (oʰᵛ)⚥ mice. The formation of testosterone was similar in all incubations. A number of unidentified metabolites of androstenedione were detected in the Tfm (oʰᵛ)⚥ incubations which were not present in the Tfm (o⁺) incubations.

Finally, the aromatization of testosterone was studied in hypothalamus and cortex incubations of normal BALB/c♂, BALB/c♀, and testicular feminized Tfm (o⁺)⚥ and Tfm (oʰᵛ)⚥mice. A new, rapid method was developed for studying aromatization based toluene-sodium hydroxide partitioning and a novel estrogen methylation procedure known as extractive alkylation. Using this method the formation of estrone and estradiol was detected. The conversion of testosterone to estradiol by hypothalamus minces was about 1.5 times greater in normal BALB/c♂ than BALB/c♀ and about the same as in Tfm (o⁺) and Tfm (oʰᵛ). Total aromatization by cortex minces was about 30-50% that of the hypothalamus. The major metabolite of testosterone in normal BALB/c ♂ and BALB/c ♀ incubations was estrone while in the Tfm (o⁺) and Tfm (oʰᵛ) incubations it was estradiol-17β.

The studies confirm the work of others which suggests that the metabolism of steroids is altered in the liver and testis of the Tfm (o⁺)/Y⚥ mouse. The present work extends these observations to include a number of other mice carrying the Tfm and sxr genes. Using the extractive alkylation technique aromatization was detected in Tfm hypothalamus and although the overall quantitative yields of estrogen from testosterone were similar to normals, qualitative differences were evident which may be significant to the explanation of altered hypothalamic-pituitary gonadotrophin relationships in Tfm (o⁺) and Tfm (oʰᵛ) mice.

abstract: Master of Science (MS)


title: Sedimentological analysis of Neoproterozoic glacigenic successions in Norway and Scotland

contributor:
Eyles, Carlyn H.
School of Geography and Geology

subject: Geography Geology Geography

abstract: There is much debate regarding the severity of glaciation during the Neoproterozoic, particularly in response to the snowball Earth hypothesis that suggests ice repeatedly covered the Earth from equator to poles during this time. A detailed sedimentological analysis of the Neoproterozoic Smalfjord Formation of northern Norway and the Port Askaig Formation of Scotland was conducted in order to reconstruct the nature of paleoenvironmental change and assess the evidence for such severe glacial conditions. This study focuses on identifying the depositional origin of Neoproterozoic diamictites and the assessment of the relative importance of tectonics and climate in controlling sedimentation. Analysis of the Smalfjord Formation in two different areas of northern Norway shows that diamictites and associated facies were primarily deposited by sediment gravity flow processes, making determination of past ice mass form or distribution impossible. Sedimentological and allostratigraphic analysis of the Port Askaig Formation, showed that the thick succession of diamictites interbedded with sandstones, conglomerates and mudstones was deposited in a glacially-influenced marine setting affected at different stages of its development by both tectonic and climatic forces. Detailed analysis of the Great Breccia, a distinctive diamictite unit within the Port Askaig Formation, showed that it was the product of catastrophic subaqueous mass failure indicating substantial tectonic activity during the early stages of Port Askaig deposition. Elsewhere in the succession, diamictites show a greater degree of glacial influence on sedimentation and record fluctuating climatic conditions. This study shows that diamictites in Neoproterozoic successions cannot be presumed to represent glacial conditions. Sedimentation at both study sites appears to have been influenced by tectonic activity related to basin development. The Smalfjord and Port Askaig formations contain only limited evidence for glacial influence on sedimentation and do not appear to record the severe glacial conditions required by the snowball Earth hypothesis.

abstract: Doctor of Philosophy (PhD)


title: PEO and PEO-heparin modified surfaces for blood contacting applications

contributor:
Brash, J.L.
Chemical Engineering

subject:
Chemical Engineering
Chemical Engineering

abstract: The synthesis and characterization of various thiolated polyethylene oxide (PEO) polymers constitute a significant part of the work, from linear PEOs with different molecular weights, and different end groups, to star-type, multiarmed PEOs, to linear PEOs in which one end bears a thiol group and the other a bioactive group. Different reaction protocols were used for the synthesis of the different PEOs. Terminal thiol groups were attached to PEO by reaction with mercaptoacetic acid or cystamine. Thiolated PEOs were chemisorbed to gold films deposited on polyurethane or silicon wafer substrates. Combinations of PEO and chain-end functionalized PEO were used to passivate the gold films and impart specific bioactivity respectively. The interactions of the modified surfaces with blood and blood proteins were investigated using radiolabeling, electrophoresis and immunoblotting methods. In measuring protein interactions with gold-based surfaces using radioiodine-labeling methods, it was found that the radioactive iodide ions (125 I- ) in the protein solution became bound to the surface along with the protein. Data on the adsorption of fibrinogen and albumin from buffer and plasma onto surfaces modified with different PEOs showed that adsorption decreased with increasing PEO molecular weight, irrespective of the group on the "outer" end of the PEO (hydroxyl or methoxyl). Surfaces were also prepared using PEO to which heparin was conjugated. Unfractionated heparin and low molecular weight heparin conjugated PEO were used to modify both gold and polyurethane surfaces. Both the passivation effect of PEO and the anticoagulant effect of heparin were found to be evident for these surfaces. (Abstract shortened by UMI.)

abstract: Doctor of Philosophy (PhD)


title: Hemoglobin oxygenation of a two-layer tissue-simulating phantom from time-resolved reflectance

contributor:
Patterson, Michael S.
Physics

subject: Physics Physics

abstract: A dual wavelength time-resolved reflectance system was developed for monitoring hemoglobin saturation noninvasively. The ability of the system to determine the optical properties of tissue-simulating phantoms was examined. To quantify the accuracy of the technique in monitoring hemoglobin saturation, measurements were performed in a homogeneous phantom containing human erythrocytes in a scattering solution. The hemoglobin saturation of this phantom could be controlled and monitored with an alternate technique. After system validation in this simple model, a more realistic, two-layer phantom model was investigated. The top layer was chosen to simulate either skin or fat and the oxygenation of the bottom layer, which corresponded to muscle, was controlled. The thickness of the fat layer was varied from 1.5 to 10 mm to investigate the effects of increasing the top layer thickness. Time-resolved measurements of reflectance, performed through the top layer were analyzed with a simple homogeneous diffusion model to quantify the hemoglobin saturation of the bottom layer. These data were compared with simultaneous measurements of oxygenation made directly in the bottom layer. Errors in estimating hemoglobin saturation with this method ranged from 5-11% depending on top layer thickness. Preliminary in vivo measurements were also undertaken which demonstrated promising results, although no comparative technique was used in these studies.

abstract: Doctor of Philosophy (PhD)


title: Regulation of viral and cellular gene expression in cells infected with herpes simplex virus

contributor:
Smiley, James R.
Biology

subject: Biology Biology

abstract: When herpes simplex virus (HSV) infects a cell, viral genes are expressed to high levels, while cellular gene expression is dramatically inhibited. The major goal of the work described in this thesis was to understand the molecular basis for differential expression of viral and cellular genes in HSV infected cells. A two part-approach was taken to examine this problem. First, I compared the expression of virally-transduced and endogenous β-globin genes in HSV infected cells. These experiments were prompted by previous work which demonstrated that an HSV transduced rabbit β-globin gene isefficiently expressed in infected Vero cells, a result that was in apparent conflict with previous experiments demonstrating that HSV infection inhibits the expression of the mouse β-globin gene resident in mouse erythroleukemia cells. This approach demonstrated that HSV products inhibit the expression of an endogenous β-globin gene while transactivating the expression of a virally transduced β-globin gene. These results illustrate that the selective inhibition of cellular gene expression plays an important role in the preferential expression of genes associated with the viral genome. Therefore, the second approach involved a detailed investigation of the herpes simplex virus vhs gene product, one of the viral functions that inhibits cellular gene expression. I have confirmed that the vhs effect requires the HSV UL41 open reading frame. in addition, I identified the vhs proteni as a 58kDa phosphoprotein that is packaged into virions. Using several approaches I demonstrated that the vhs protein interacts with the HSV transcription factor VP16. In addition, I have data which suggests this interaction downregulates the vhs function and that this downregulation might play a key role in the preferential expression of viral genes in the HSV infected cell.

abstract: Doctor of Philosophy (PhD)


title: Extended end-plate connections for lnk-column joints of eccentrically braced frames

contributor: Civil Engineering and Engineering Mechanics

subject:
Civil Engineering
Civil Engineering

abstract:
Based on a limited number of experiments, the current practice is to use fully welded link-column connections for links in eccentrically braced frames (EBFs). Since the use of field welded connections has its limitations, the use of bolted connections may be an attractive alternative. The extended end plate bolted connection (EEP) was selected for use in link-column join applications in eccentrically braced frames.

The link-column connection is required to behave in a ductile manner. This would enable the shear link to develop its full plastic capacity and thus the EBF would be able to dissipate the earthquake input energy. In addition, the link-column connection should not result in any degradation of the EBF lateral stiffness. To test the ability of EEP connections to satisfy both those requirements, a two phase research program was performed.

The first phase of study is experimental in nature and involves the testing of end plate connections under severe cyclic loading. The cyclic load is used to model the severe load reversals associated with a major seismic event. The effect of bolt size, end plate thickness and the use of end plate stiffeners on the performance of the joint was evaluated. It was found that properly designed EEP connections showed ductile performance. Links with extended end plate connections developed ultimate forces and reached deformation angles comparable to those with fully welded connections. Guidelines for designing EEP connections for link-column joints are proposed.

Because of the severe inelastic behaviour of the shear links, their proper modelling is important for the accurate analysis of an EBF. In the second phase of this research, a simple yet effective link element model is developed. This model was included in the computer code DRAIN-2DX, of Prakash and Powell (1992). Comparisons with previous and current results confirm the accuracy of this new link model.

An extensive dynamic analysis of EBFs with semi-rigid joints was conducted to shed some light on the effect of EEP connections on the performance of EBFs. A six-story, three-bay EBF and a twenty-story, single-bay EBF were selected. These EBFs were subjected to several strong ground motion records. The developed shear link model was used in the computer modelling of these frames. Several designs of these frames involving different degrees of connection flexibility are analyzed. The various design responses are compared to each other to determine the effect of connection flexibility on the response of EBFs. It was found that properly designed bolted EEP connections can be used as alternative to welded link-column joints in eccentrically braced frames.

abstract: Doctor of Philosophy (PhD)


title: Together we survive: East cree material culture

contributor:
Preston, R.J.
Anthropology

subject: Anthropology Anthropology

abstract: The main goals of this thesis are to recontextualize, to rehistoricize and to facilitate the symbolic repatriation of East Cree material culture. As a consequence of the British presence in the Hudson Bay Territory, from the seventeeth century onward a substantial number of inadequately documented material objects were collected from teh Cree of the James Bay region and ultimately accessioned into European and North American museum collections. By using these objects as primary documents, we are able to gain knowledge of the native world view and to reconstruct the social history of both the artifacts and their makers. Foremost is the need to establish a definitive ethnic identification of this material. This identification, derived from both external and internal evidence, allows further analysis of particular items which contribute towards a general understanding of East Cree history and world view. Evidence for embedded symbolism expressed in the decorative elements of beaded hoods reveals the dynamic and negotiated realities of native and European relations. While reworking and incorporating European aesthetics and ideals into their material culture, the Cree retained components paramount to native world view. As well, a socio-semiotic analysis of cloth leggings reveals their communicative role in visually projecting encoded messages to be decoded not only by members of linguistically similar groups but also by others, both human and animal, from outside these groups. On a more abstract level, metaphors of protection and provision as tangibly rendered in the ubiquity of lines and knots demonstrate the interdependence and connnectedness of Cree culture. The connecting link throughout is the prevalent theme that "together we survive." This refers not only to the actions and world view of the Cree, but also to the objects that have survived and which are not source material for reconstructing the past. Now that these initial steps have been taken, the Cree can recover this aspect of their history.

abstract: Doctor of Philosophy (PhD)


title: The doll of english fiction: Hardy, zola and the politics of convention

contributor:
Ferns, John
English

subject:
English Language and Literature
English Language and Literature

abstract:
The thesis presents a detailed textual and contextual study of Thomas Hardy as reader of Emile Zola. At the centre of the discussion is George Moore's metaphor for the novel as an inanimate "doll"--a child-like object of sexless implicity, the political and economic offspring of social convention, variously violated at the hands of its keepers and its readers (Literature at Nurse, 1885). Hardy's own attempts to demolish "the doll of English fiction" and to create a more "virile" type and of novel are viewed in the context of his reading of Zola and in relation to the controversy surrounding Henry Vizetelly, Zola's English pubilsher, who was convicted on charges of obscene libel in 1888 and 1889.

Hardy's reading of Zola came, it is argued, at a particularly critical point in his career and was, in some respects, crucial in determining the tone, imagery and form of the later novels. Nevertheless, his reading of Zola was not, of course, an exclusive factor in determining Hardy's changing emphasis throughout the period, but rather was one of a number of determining factors. The purpose, then, is to provide a detailed context for Hardy's readership, and to then examine the relationship between Zola and the body of Hardy's work in the decade between 1886 and 1896, or from the writing of The Woodlanders (1887) to the publication of Jude the Obscure (1896). The metaphorical doll, representing, in part, the surrounding system of the English novel, of the gendered reader and the socially, politically and economically driven construction of a prescribed morality, provides a constant framework within which to view Hardy's reading of Zola and the writing of his later fiction.

abstract: Doctor of Philosophy (PhD)


title: The contextual approach in health research: Two empirical studies

contributor:
Birch, Stephen
Health Research Methodology

abstract: Researchers are being encouraged to consider contextual influences on health-related outcomes. To support this perspective, two context-sensitive studies were conducted. The first study explored the utilization of a research report by Ontario public health units, and examined whether utilization differed by involvement in the research process. Research utilization was conceptualized as a three stage process (reading, information processing and application). Using a case study design, results from three "involved" public health units and three "uninvolved" units demonstrated that inclusion in the research process led to a greater understanding of the analysis and increased the value associated with the report. Involvement did not, however, lead to greater research utilization. An associated contextual analysis provided a rich backdrop, highlighting the general challenges of implementing research-based guidelines given front-line workers' current realities. The second study examined the influence of contextual level (e.g., health region level) socioeconomic status on a woman's lifetime mammography screening uptake. A secondary data analysis was conducted using Ontario data from the 1996 National Population Health Survey. Logistic hierarchical multilevel modelling was used to examine the regional variation in mammography uptake, and to examine the role of contextual and individual level variables on regional variation. The estimated average proportion of Ontario women, aged 50-69, who reported ever having had a mammogram was 0.86. Results demonstrated modest variations among health regions in ever having had a mammogram. These variations could not be explained by the variables considered in this study. Individual level variables demonstrated an association with mammography uptake, as did regional level education and regional median family income. Furthermore, each of these latter two contextual variables demonstrated interaction effects with the individual level variable, "social involvement." Thus, contextual variables played a significant role in mammography uptake. Contextual circumstances ought to be considered during the development of breast health promotion programs and policies.

abstract: Doctor of Philosophy (PhD)


title: Community Radio: The Development of a Voluntary Organization

contributor:
Marshall, Victor
Sociology

subject: Sociology Sociology

abstract:
The primary purpose of this thesis is ethnographic. It is a case study of the development of Canada's first non-profit, urban community radio station, CKWR-FM. The people associated with CKWR-FM sought to develop a citizen access facility, in which all programming would be done by local residents. Their station was owned and managed by a voluntary organization, Wired World, Inc., membership in which was to be widely open to area residents. Planned as a non-commercial facility, the station was to be financed primarily from local charitable donations.

In addition to its ethnographic intent, the thesis offers some insight into the process of organizing to effect social change, providing an opportunity to critique some of those aspects of organization theory concerned with voluntary associations. The thesis demonstrates the importance of understanding the development of such an organization from a social action perspective. Two organizational characteristics are found to particularly noteworthy in this case study. One concerns the meaning of voluntarism and the effects of a dependence on volunteers. The other concerns the relationship between government and the voluntary sector.

abstract: Master of Arts (MA)


title: Molecular evolution of sex determination genes in closely related species of the Drosophila melanogaster subgroup

contributor:
Singh, R.S.
Biology

subject: Biology Biology

abstract: Recent studies have highlighted the importance of sex and reproductive related traits in speciation. Hence, an evolutionary examination of the primary regulators of sexual differentiation is an important step in understanding the origins of phenotypic diversity. In this thesis, a molecular analysis of sequence variation is performed on the three interacting sex determining genes, transformer (tra ), transformer-2 (tra-2 ) and doublesex ( dsx ), among closely related species of the Drosophila melanogaster subgroup. At the dsx locus, both female- and male-specific DSX isoforms are found to be conserved relative to other loci sequenced from species of the D. melanogaster subgroup. However, levels of selective constraints on the male-specific portion of the dsx protein has varied considerably across Dipteran lineages and indicate the apparent heterogeneity in selection pressures across taxa. Meanwhile, tra and tra-2 are demonstrated to be among the most rapidly evolving loci found in the D. melanogaster subgroup. The presence of large arginine-serine rich insertions in sibling species indicate that TRA is tolerant to substantial amino acid change. Generally, within and between species patterns of variation in the sibling species do not deviate from a neutral model of evolutionary change. At the tra-2 locus, the ratios of replacement to synonymous substitutions were significantly different within vs. between species indicating the presence of diversifying selection at this locus. Polymorphism data from D. simulans corroborates this result and thus, provides evidence that positive selection may be acting directly on a gene involved in the primary sex determination hierarchy. The high levels of variability found among sex determining genes indicate the evolutionary potential of this important sexual system. The amenability of this sexual system to tolerate large genetic perturbations may expedite the generation of evolutionary novelties. Since sex determination genes control various components of the mating system, this high degree of genetic variability may be an important source of heritable genetic material for sexual selection--an important driver of speciation--to act upon.

abstract: Doctor of Philosophy (PhD)


title: The effect of polymer structure and interaction on paper strength

contributor:
Pelton, Robert
Chemical Engineering

abstract: Polymers are routinely used in paper making to enhance the strength of paper. The strength enhancing effect of polymers on paper is generally attributed to the increase in the fiber-fiber bond strength. This thesis focuses on the links between the structures and interactions of adsorbed polymers and the resulting strength of fiber-fiber bonds. Dextran was chosen as the model of strength enhancing polymers in this work. The molecular weight, charge density, and hydrophobicity of the dextrans were varied. Mixtures of dextran and hydrophobically modified dextrans were employed to investigate the role of adsorbed polymer compatibility in fiber-fiber bonding. Cationic dextran with different charge densities (0.161-0.488 meq/g) was prepared. Hydrophobically modified dextran was made by the reaction of dextran with straight chain saturated C3, C4 and C6 fatty acids. The incompatibility of dextran and hydrophobic dextran was evaluated by means of the biphase formation of an aqueous mixture of the two polymers. The adsorption behavior of dextrans on pulp fiber was measured. It was observed that the maximum amount of adsorption increased with a decrease in the molecular weight and charge density of the dextran. The strength of paper was evaluated using tensile strength and Scott bond tests. The strength enhancing effect of dextran was given as a function of molecular weight, charge density, hydrophobicity, and incompatibility with hydrophobic dextran. When fiber surface was saturated with dextran, it was found that the tensile strength of paper did not depend on the molecular weight of the dextran in the range investigated (77,000 to 2000,000). The charge density of the dextran affected the strength of paper by changing the maximum amount of dextran adsorbed on fibers. Introducing hydrophobic groups into dextran decreased the strength enhancing ability of dextran. The strength enhancing mechanism of dextran was proposed to be the formation of dextran intermolecular bonds between fibers. For the first time, the role of polymer incompatibility in determining the strength of paper was demonstrated in this work. It was found that the bond strength between fibers coated with two incompatible polymers was weaker than that obtained from the single polymer coated fibers. The Page equation, along with the model developed in this work, was applied to calculate the bond strength for each type of bonding.

abstract: Doctor of Philosophy (PhD)


title: The role of monocyte/macrophages in immune-mediated epithelial pathophysiology: Implications for inflammatory bowel disease

contributor:
Perdue, Mary H.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: Crohn's disease is characterized by altered epithelial physiology including ion secretion and disrupted epithelial barrier. It has been suggested that the pathophysiology and epithelial damage in Crohn's disease may be due to inappropriate immune reactions. The purpose of my studies was to examine the role of cells of the monocyte/macrophage lineage in mediating epithelial physiology. Confluent monolayers of the T84 colonic epithelial cell line were co-cultured with human monocyte/macrophages (peripheral blood monocytes [PBM], or lamina propria mononuclear cells [LPMC]) from controls or patients with crohn's disease ± the activating agents, bacterial lipopolysaccharide (LPS) and/or the bacterial tripeptide, f-met-leu-phe (fMLP). Monolayers were then removed and epithelial secretory (baseline short circuit current [Isc] and ΔIsc to 10-5 forskolin) and barrier transepithelial resistance [TER]) were measured 48h later in the Ussing chambers. Epithelial functional parameters were unchanged after co-culture with non-activated PBM. Addition of activating agent (LPS or LPS/fMLP) significantly increased Isc and reduced TER with PBM from both control and Crohn's disease. No pathophysiology occurred after co-culture with control LPMC ± LPS. However, non-activated LPMC from patients with Crohn's disease spontaneously induced changes in T84 physiological parameters similar to those produced by activated PBM. A non-pathogenic control strain of E. coli , added to the luminal compartment of the culture well, induced comparable changes in epithelial physiology in the presence of PBM. The role of Tumor Necrosis Factor α (TNFα) in the regulation of epithelial secretory and barrier functions was examined. TNFα production was significantly increased by activated PBM and non-activated LPMC from Crohn's disease. The epithelial abnormalities could be successfully abrogated by inclusion of a neutralizing antibody to TNFα. These studies show that monocyte/macrophages are potent immune cells which may mediate some of the pathophysiology in inflammatory disorders of the gut. TNFα is a key factor mediating the monocyte/macrophage induced epithelial pathophysiology.

abstract: Doctor of Philosophy (PhD)


title: Second-Order Limit-Switched Loop

contributor:
Taylor, D.P.
Electrical Engineering

subject:
Electrical and Electronics
Electrical and Electronics

abstract: Time Division Multiple Access (TDMA) or burst mode operation of a communication system requires that synchronization be achieved within an alloted preamble time or else the entire data burst may be lost. A conventional phase-locked loop occasionally exhibits a prolonged lock-up time known as hangup, especially when the initial phase error falls within the neighbourhood of 180 degrees, and is therefore not suitable for synchronization of this type of system. The main purpose of this work is to extend the investigation of a modified phase-locked loop which is termed a limit-switched loop (LSL). The LSL offers a faster lock-up time and lower probability of hangup. The transient probability density function (pdf) of the phase error for a first-order LSL and the steady-state pdf of the phase error for the second-order LSL have been obtained, using Fokker-Planck techniques. Simulations and experimental methods have been used to obtain the probability of hangup on a low frequency model which also reveals the optimum range for the switching time.

abstract: Master of Engineering (ME)


title: Studies on Biochemical and Pharmacological Effects of Cyclophosphamide and Phosphorodiamidic Acid

contributor:
Hillcoat, B.L.
Biochemistry

subject: Biochemistry Biochemistry

abstract:
Recent evidence suggests that phosphorodiamidic acid is formed from cyclophosphamide in vivo and in vitro and may be the active form of this drug.

We have studied the effect of phosphorodiamidit acid and cyclophosphamide on the growth of the mouse leukemic cell lines LM4 and LS2 in culture. On this basis, phosphorodiamidic acid was at least 100 times more potent than cyclophosphamide in inhibiting growth. It also produced enlargement of cells, an effect not seen with cyclophosphamide.

Although two metabolites of cyclophosphamide, phosphorodiamidic acid and acrolein were isolated and identified, attempts to measure these metabolites accurately were unsuccessful. Consequently the stoichiometry of the conversion could not be determined.

Phosphorodiamidic acid significantly increased the amount of cross-linked DNA after incubation with intact LM4 cells or isolated nuclei from these cells. Cyclophosphamide had a similar effect only in the isolated nuclei.

These findings strengthen the proposed role of phosphorodiamidic acid as the active metabolite of cyclophosphamide.

abstract: Master of Science (MS)


title: Strain relaxation in indium gallium arsenide phosphide films on indium phosphide substrates

contributor:
Weatherly, G.C.
Materials Science and Engineering

subject:
Materials Science and Engineering
Materials Science and Engineering

abstract: Transmission electron microscopy (TEM), atomic force microscopy (AFM) and scanning electron microscopy (SEM) have been used to study the strain relaxation mechanisms in In1-x Gax Asy P 1-y films grown on (100) InP substrates using gas-source molecular beam epitaxy (MBE). Highly anisotropic strain relief behavior was found in 2% tensile strained In0.25 Ga0.75 As and In0.72 Ga0.28 P films. In the first stages of film growth, the strain in [01¯1] cross-section was relieved by twinning, while it occurred by cracking in the orthogonal [011] cross-section. In the In0.25 Ga0.75 As film cracking was a transitory phenomenon. Crack healing was observed in the 500 nm thick film. Cracks were observed to penetrate into the substrate and deviate from an (01¯1) to (11¯1) or (1¯1¯1) planes. A critical stress intensity argument was developed to explain substrate cracking. A dislocation analogue for a surface crack was developed to successfully account for the experimental value of the ratio of crack opening displacement to normal surface displacement associated with cracks in In0.72 Ga0.28 P films. The 90° partial dislocations were found to form prior to the formation of either cracks and or 60° dislocations in In0.25 Ga0.75 As films, which is consistent with the critical thickness and nucleation calculations. Elastic strain energy computations show that the 90° partial dislocations also provide the most effective relief of elastic strain energy for films with smaller thickness, while cracks are the most effective strain relaxation mechanism for thicker films. It has also been shown both experimentally and theoretically that the twin thickness increases with an increase in the film thickness. The free surface plays an important role in determining the equilibrium position of misfit dislocations in thin epitaxial films. The computations based on a force argument show that the core of the dislocation lies close to the interface when the film is softer than the substrate. On the other hand, when the film is elastically stiffer than the substrate, the core of the dislocation is predicted to lie at some distance from the interface in the softer substrate. This prediction agrees with the experimental observations that the 90° partial dislocations bounded by stacking faults are frequently observed to locate inside the InP substrate over a range of a few hundred angstroms. The composition modulation in In1-x Gax As y P1-y films was found to be associated with the chemical spinodal in this alloy. Films with compositions lying within the chemical spinodal at growth temperature show fine scale composition modulation contrast. The composition modulation scales with the size of the strain-induced surface facets.

abstract: Doctor of Philosophy (PhD)


title: Rational and Experiential Grounds for Belief in God: the Teleological Argument in the Work of Charlee Hartshorne

contributor:
Robertson, J.
Going, C.
Religion

subject: Religion Religion

abstract: The question behind this thesis is "What does Charles Hartshorne conceive to be the rational and experiential grounds for belief in God?". This question is approached through a study of Hartshorne's distinctive formulation of the teleological argument and the central features of that argument. Attention is given to the components of Hartshorne's natural theology in order to establish the context within which to approach Hartshorne's formulation of the argument, to the principles of his metaphysics which I see to underpin his formulation, to the proper manner in which to conceive of the argument, the cosmic organism analogy, and to his proposed solution to the problem of evil.

abstract: Master of Arts (MA)


title: Use of the finite difference time domain method to study broadband antennas for millimeter wave point-to-point and point-to-multipoint communications

contributor:
Litva, John
Electrical and Computer Engineering

subject:
Electrical and Computer Engineering
Electrical and Computer Engineering

abstract: This thesis presents an in-depth investigation of new broadband millimeter wave antennas, which can be used in millimeter wave point-to-point and point-to-multipoint communications. A very powerful design tool--the Finite Difference Time Domain (FDTD) method is presented in its regular uniform grid form, which is referred to as Yee's method, its non-uniform grid form, and its General Curvilinear Coordinate (GCC) form. Accompanying formulas are presented in each case. The advantages of these different formulas are discussed, their use for solving different complex electromagnetic problems is demonstrated, as well. Different absorbing boundary conditions (ABC) are used to design antennas, their beam forming networks and transitions, for example Mur's first order ABC, Litva's dispersive ABC and Modified Perfect Matched Layers (M-PML). Here Litva's ABC is presented in detail, and some case studies are given to prove that it is a very good ABC for printed circuit applications. A research based FDTD 3-Dimensional Structure Simulator (FDTD 3D SS) is used to design these new wide-band antennas and transitions. More than 500 simulations have been calculated for this study within less than a year. The Tapered Slot Antennas (TSA) and different type feed structures for TSA are reviewed in Chapter 2. As a member of the class of traveling wave antennas, the TSA's are wide-band elements with very good directivities. Based on the Suspended Microstrip Line (SML) and the Inverted Microstrip Line (IML), three new feed structures have been developed, by using FDTD 3D SS, for millimeter wave wide-band applications. The Vivaldi antenna, which belongs to the traveling wave antenna category and shares the same features as TSA, is used as a very short element (antenna length L < λo /2) to design an 120-degree-vertical-polarization sector antenna. The experimental study shows that the design gives very good results and meets the specifications in real applications. It has a potential to be used as a sector antenna with different horizontal beam-widths. This design shows antenna engineers a novel approach to design sector antennas without worrying about the antenna input impedance bandwidth. (Abstract shortened by UMI.)

abstract: Doctor of Philosophy (PhD)


title: CYSDEM User's Manual

contributor:
Kenworthy, D.J.
Computation

abstract:
CYSDEM is a new FORTRAN based simulation language. It is used to simulate business information systems. The main feature of CYSDEM is that it concentrates on delays and distortions, to which information in actual systems is subjected to. Therefore, CYSDEM allows a more realistic representation of the movement of data within an information system.

CYSDEM is based on a schematic representation of the information system under consideration, called the CYBERSTRUCTURE. The CYBERSTRUCTURE is constructed by the user. It helps the user in identifying relevant information.

Any new computer language, requires careful verification and complete documentation. This report contains an introduction to simulation and a user's guide. Partial verification of CYSDEM was performed distribution system from Forrester's "Industrial Dynamics". The example is explained and the results are included in this report.

abstract: Master of Science (MS)


title: Inter- and intramolecular reactions of dialkoxycarbenes

contributor:
Warkentin, John
Chemistry

subject: Chemistry Chemistry

abstract: This dissertation involved a study of the mechanistic and synthetic potential of nucleophilic carbenes in solution. More specifically, it deals with the inter- and intramolecular reactions of dialkoxycarbenes generated thermally from oxadiazoline precursors. Dialkoxy oxadiazolines (I ) decompose thermally via loss of N2 and acetone to afford dialkoxycarbenes (II ) (Scheme I). Dialkoxycarbenes are singlet carbenes which possess nucleophilic character because of heteroatom electron donation into the vacant p -orbital of carbon. This is best illustrated by writing the dipolar resonance contributor (II ) with formal negative charge at the carbene carbon and formal positive charge on oxygen. This special property of dialkoxycarbenes allows them to take part in a wide variety of chemical reactions including fragmentations, and inter- and intramolecular additions. The first section of the dissertation describes the first example of a dialkoxycarbene fragmentation to radical pairs in solution in which both the carbene and the radicals could be trapped. Thermolysis of cinnamyloxymethoxy oxadiazoline (III ) afforded the corresponding dialkoxycarbene (IV ) which fragmented to methoxycarbonyl radical (V ) and phenylallyl radical (VI ) (Scheme II). The second section describes the use of dimethoxycarbene as a convenient synthetic tool for the ring expansion of strained cyclic carbonyl compounds. Thermolysis of dimethoxy oxadiazoline (VII ) afforded dimethoxycarbene (VIII ), which in the presence of carbonyl compounds (IX ) yielded products (X ) of formal carbene insertion in-between the carbonyl group and the alpha carbon atom (Scheme III). In unsymmetrical carbonyl-containing compounds, carbene insertion was selective, favouring insertion in-between the carbonyl group and the most electron-rich alpha carbon. The final section highlights advances in the area of intramolecular dialkoxycarbene additions to alkynes. In particular, a preliminary investigation into the area of tandem carbene cyclizations is discussed. This work involved the synthesis and thermolysis of dialkoxy oxadiazolines containing two tethered alkyne units. It was envisioned that intramolecular carbene addition to one alkyne unit would afford a vinyl carbene (XI ) which could add to a second alkyne tether to yield a second vinyl carbene (XII ) (Scheme IV). This methodology has the potential for synthesis of multicyclic systems in a one-pot reaction.

abstract: Doctor of Philosophy (PhD)


title: Mechanisms of oxygen-chemosensitivity in adrenal medullary chromaffin cells from the developing rat and mouse

contributor:
Nurse, Colin A.
Biology

subject: Biology Biology

abstract: The primary goal of this thesis was to uncover the mechanisms of oxygen-sensing in developing chromaffin cells from the rat and mouse, using primary short-term cell cultures of chromaffin cells. The experimental approaches relied on patch clamp techniques to record ionic currents and membrane potential, carbon fibre electrochemistry to record catecholamine secretion from cell clusters, and fluorescent indicators to measure reactive oxygen species generation. Hypoxic chemosensitivity was found in embryonic and neonatal, but not juvenile chromaffin cells from both the rat and mouse. Exposure to hypoxia or anoxia caused a reversible suppression of whole-cell current, which was comprised of the differential modulation of three K+ currents: (1) suppression of a large-conductance Ca2+ -dependent K+ current; (2) suppression of a delayed rectifier K + current; and (3) activation of an ATP-sensitive K+ current. Hypoxia also induced membrane depolarization that was not initiated by any of these three voltage-dependent K+ currents. Additionally, hypoxia broadened action potentials in chromaffin cells that showed spontaneous activity, and this was mediated by a prolongation of the time course of membrane repolarization. All of these factors likely contribute to catecholamine secretion by enhancing the influx of Ca2+ through depolarization-activated L-type Ca2+ channels. Two sets of experiments were designed to identify the oxygen sensor in neonatal chromaffin cells. First, cells from transgenic mice, deficient in the gp91phox component of the putative O 2 -sensor protein, NADPH oxidase, responded to hypoxia in the same way as wild type cell, indicating that NADPH oxidase is not primarily responsible for oxygen sensitivity in these cells. Second, inhibitors of the proximal electron transport chain (e.g. rotenone and antimycin A) mimicked and attenuated the hypoxic response, while inhibitors of the distal electron transport chain (cyanide) and uncouplers of oxidative phosphorylation (2,4-dinitrophenol) had no effect. Furthermore, reactive oxygen species production, primarily H2 O2 , decreased during exposure to hypoxia or inhibitors of the proximal electron transport chain, revealing a potential mitochondrial mechanism for 'sensing' of the hypoxic stimulus. (Abstract shortened by UMI.)

abstract: Doctor of Philosophy (PhD)


title: Environmental temporal determinants of community variability using natural aquatic microcosms

contributor:
Kolasa, Jurek
Biology

subject: Biology Biology

abstract: Histories, biotic factors, and abiotic factors interact to determine biodiversity. These factors also influence community composition, community structure, and community constancy (persistence) over time. By examining multiple communities from a common species pool in a system that spans a range of physical conditions, it may be possible to determine the role environmental variables play in forming and maintaining community composition and structure, especially over time. Species richness and diversity were determined by abiotic pool conditions such that the observed community consisted of tolerant species that accumulated over time. These abiotic variables also can be used to represent habitat heterogeneity. I showed that increased habitat heterogeneity promoted increased biodiversity, which, in turn, further increased biodiversity by self-generation of heterogeneity. Frequency of pool desiccation was another abiotic variable considered and it was found that diversity, richness, and abundance all decreased with increased frequency of desiccation while compositional stability decreased. Temporary pools were shown to have a similar "type" of community structure; one dominated by a few species with good dispersal and colonization abilities. One abiotic variable, pool salinity, was found to most strongly influence community composition and structure. For example, freshwater pools were dominated by ostracods and insects while brackish water pools were dominated by copepods. As salinity increased, ostracod abundances decreased while copepod abundances increased. As expected, community constancy was greatest over short temporal intervals. Environmental variability reduced community constancy. Pool temperature was shown to affect species abundances but pool salinity determined the community composition. Increased environmental variability (based on temporal changes in physicochemical variables) also resulted in increased community and population variability with community structure being more variable in unstable habitats. In conclusion, much of the results indicate that communities respond independently and asynchronously to environmental variables.

abstract: Doctor of Philosophy (PhD)


title: Immunochemical Techniques in Clinical Analysis

contributor:
Corsini, A.
Gauldie, J.
Chemistry

subject: Chemistry Chemistry

abstract:
In an attempt to develop a new sensitive immunoassay procedure to measure biologically important small molecular weight compounds in human plasma or serum, the principle of inhibition of antigen-antibody precipitation by free antigen as detected by automated nephelometry was investigated. The assay procedure was optimized for maximum sensitivity. The characteristics of the optimized system are described and with the available instrumentation, the lower level of detection of free digoxin (a cardiac glycoside) was shown to be 2 nanograms. The results demonstrate the successful application of the principle, but fall short of providing a reasonable alternate to the radioimmunoassay of digoxin in human plasma or serum for routine clinical use.

A fast and cheap method for the separation of free and antibody-bound ligand, as applied to established radioimmunoassay techniques, was developed using chemically treated and heat-killed Staphylococcus aureus bacteria. In application to the measurement of a small molecular weight compound (digoxin) and a serum protein (ferritin), it was demonstrated to have good correlation with currently utilized techniques. This alternate method is shown to be suitable for routine clinical diagnostic purposes.

abstract: Master of Science (MS)


title: Interference suppression for 121.5/243 MHz SARSAT signals

contributor:
Carter, C.R.
Electrical and Computer Engineering

abstract: When an aircraft or marine vessel is in distress, the emergency unit is activated either automatically or by manually setting a switch. The signal is then received by an orbiting satellite as it sweeps out a path over the search and rescue satellite aided tracking (SARSAT) region of interest. Due to the relative motion between the satellite and the Emergency Locator Transmitter (ELT) or the Emergency Position Indicating Radio Beacon (EPIRB) unit, the signal received at the spacecraft is Doppler shifted. New processing techniques for detecting ELT signals in an interfering background are investigated, based on not only computer simulations but also experimental data. The new methods involve the use of the Geometrically Averaged Spectrum (GAS) and the Harmonically Averaged Spectrum (HAS) in addition to the Arithmetically Averaged Spectrum (AAS) adopted by the existing system. Specifically, this thesis investigates the theoretical performance of AAS, GAS and HAS averaging in practical circumstances involving signals, noise and interference. It is shown that the carrier peaks of good ELT signals can be substantially enhanced in an interfering background. The treatise identifies certain types of interference such as Carrier interference with strong or weak AM, On-Off Modulation interference, Swept Carrier interference, and Ringing Response interference. Using computer simulation, it is demonstrated that under certain conditions the effects of background interference can be greatly reduced and the detection of ELT carrier peaks can be improved by employing a combination of AAS, GAS and HAS averaging. Real SARSAT pass data signals are fed into the computer and processed using AAS, GAS and HAS averaging. The background interference postulated in this thesis is found to exist and real ELT signals are identified. ELT signals representing the NIC model and a new model, called the Frequency Modulated ELT (FME) model, are identified along with a new ELT signal for which a model cannot presently be envisaged. The results of letting AAS, GAS, and HAS work together are compared to that of using only AAS. It is seen that the new strategy shows superior performance over the original method in a congested signal environment even though interference power exceeds ELT signal power. (Abstract shortened by UMI.)

abstract: Doctor of Philosophy (PhD)


title: Interactions of vampire bat plasminogen activator, tissue-type plasminogen activator, and TNK-variants with fibrin, fibrinogen, and the fibrin fragment (DD)E

contributor:
Weitz, Jeffrey I.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: Fibrinolysis is the process by which blood clots are solubilized. For the purposes of intravascular fibrinolysis, tissue-type plasminogen activator (t-PA) catalyzes the rate-limiting step by converting the zymogen, plasminogen (Pg), to the active enzyme, plasmin. Plasmin then degrades the fibrin meshwork, generating soluble fibrin degradation products. Because the catalytic efficiency of Pg activation by t-PA is higher in the presence of fibrin than that in the presence of fibrinogen(Fg), t-PA is designated a fibrin-specific Pg activator. Despite this designation, t-PA causes systemic plasminemia and fibrinogenolysis when given to patients. Recently, it was demonstrated that the fibrin-specificity of t-PA is compromised because (DD)E, a major soluble degradation product of crosslinked fibrin, stimulates Pg activation to the same extent as fibrin. This project was initiated to gain a better understanding of how (DD)E compromises the fibrin-specificity of t-PA by characterizing the interactions of t-PA and Pg with fibrin, (DD)E and Fg. t-PA binds to fibrin through two classes of sites, one high affinity, finger-dependent site, and one low affinity, kringle-dependent site. In contrast, t-PA binds (DD)E and Fg solely through its second kringle domain, because these interactions are blocked by lysine or its analogues. Both t-PA and Pg bind (DD)E with affinities similar to those for fibrin, thereby explaining why (DD)E stimulates t-PA-mediated Pg activation to the same extent as fibrin. t-PA primarily binds to carboxy-terminal lysines on (DD)E because the affinity of t-PA for (DD)E is reduced 160-fold when (DD)E is exposed to carboxypeptidase B (CPB) or the active form of thrombin activatable firbinolysis inhibitor (TAFIa), an endogenous CPB-like enzyme. In contrast, the affinity of Pg for (DD)E is reduced only 2- to 4-fold when (DD)E is exposed to CPB or TAFIa, suggesting that Pg binds primarily internal lysine residues on (DD)E. t-PA and Pg have weak affinity for Fg, thereby explaining why Fg is a poor stimulator of Pg activation by t-PA. These studies demonstrate that the fibrin-specificity of t-PA is compromised by its kringle-dependent interactions with (DD)E and, to a lesser extent, Fg. The limited fibrin-specificity of t-PA has prompted the development of Pg activators with greater selectivity for fibrin. Two such agents are the activator isolated from the saliva of the vampire bat (b-PA), and a bioengineered t-PA variant, TNK-t-PA. b-PA is structurally distinct from t-PA in that b-PA lacks a lysine-binding kringle. TNK-t-PA was designed to have a longer half-life than t-PA, resistance to inhibition by plasminogen activator inhibitor-1, and increased fibrin-specificity over t-PA. When the fibrin-specificities of t-PA, b-PA, and TNK-t-PA were compared, the hierarchy of fibrin-specificity (b-PA > TNK-t-PA > t-PA) correlated with the ratio of their activity in the presence of fibrin relative to (DD)E. Whereas all activators have similar activities in the presence of fibrin, they are distinguished by their activity in the presence of (DD)E. b-PA, the most fibrin-specific, exhibits minimal stimulation by (DD)E, whereas t-PA, the least fibrin-specific, exhibits the greatest stimulation by (DD)E. Stimulation by (DD)E, in turn, reflects the affinity of the activator for (DD)E. b-PA does not bind (DD)E, presumably because it lacks a lysine-binding kringle. t-PA binds (DD)E with high affinity, whereas TNK-t-PA has ∼9-fold lower affinity for (DD)E than t-PA. These studies highlight the importance of (DD)E in compromising the fibrin-specificity of t-PA. Furthermore, they suggest that the fibrin-specificity of t-PA or t-PA variants could be improved by abolishing their lysine-binding properties.

abstract: Doctor of Philosophy (PhD)


title: Imagining bodies with Merleau-Ponty

contributor:
Mitscherling, Jeff
Philosophy

subject: Philosophy Philosophy

abstract: The imagination plays a central role in Merleau-Ponty's philosophy. In his earlier works, the imagination is shown to be the creative ability of the body to have a sense of space and motility in terms of which we are able to make sense of the world. In his later works, the view that the human body is a dynamic and creative process of realizing possibilities is extended to ontology; Being is shown to be a continual dissemination of meaning through the medium of 'flesh'. Thus Merleau-Ponty's philosophy, from start to finish, is a philosophy of the imagining body. This thesis begins with a discussion of imagination theory in order to show that there are four kinds of imagining: (i) perceptual imagining, (ii) aesthetic imagining, (iii) fanciful imagining, and (iv) elemental imagining. It is shown how Merleau-Ponty's philosophy of the imagination covers each kind, and how his analysis is superior to those of many other philosophers. Merleau-Ponty's theory of the body is then examined in the light of contemporary research, with an emphasis on the nature of the body schema. The body is shown to be a creative medium for engaging with the world, and to be the basis for the four kinds of imagining. Thus the imagination theory of Merleau-Ponty is a theory of the imagining body. Finally, the role of the imagining body in ontology is explored. It is shown that Being is itself dynamic and creative, and expresses itself through the medium of 'flesh'. The imagining of Being, however, finds its ultimate expression in the imagining body as it imagines itself in perception, aesthetic production, fanciful thinking and the interpretation of elemental images.

abstract: Doctor of Philosophy (PhD)


title: Poly(4-vinylpyridine)-filled microporous membranes: Factors affecting transport and selectivity

contributor:
Childs, Ronald F.
Chemistry

subject: Chemistry Chemistry

abstract: Pore-filled anion exchange membranes containing poly(4-vinylpyridinium) have been prepared by photochemically initiated free radical polymerization of 4-vinylpyridine and divinylbenzene in the pores of a polypropylene microporous membrane followed by alkylation or protonation of the incorporated poly(4-vinylpyridine). The mass increase of poly(4-vinylpyridine) incorporated in the polypropylene substrate can be controlled from 0 to 200%. Scanning electron microscope images show that the poly(4-vinylpyridine) is distributed evenly throughout the membrane. Membrane water contents range from 25% to 65%. The membranes have ion exchange capacities up to 4.8 meq/g of dry membrane and fixed charge concentrations up to 7.2 eq/kg of membrane water. The effects of mass gain, divinylbenzene content and the size of the quaternizing alkyl group on the rate of acid transport through the membranes and the selectivity of acid transport relative to salt transport have been determined. Activation energies as well as entropy terms for the diffusion of acid through the membranes have been determined which provide information regarding the mechanism of acid transport in the membranes. The mobility of the membrane water was determined by Pulsed-Gradient Spin-Echo NMR experiments which, combined with Differential Scanning Calorimetry experiments, provides information about the structure of the water in the membranes. An increase in divinylbenzene content or an increase in the length of the quaternizing alkyl group resulted in a decrease in acid transport and a dramatic increase in selectivity of acid over salt transport. The improved performance resulting from alkylation of the pyridine nitrogen atom compared to protonation was determined to be a result of an increase in water structure and resulting decrease in the mobility of the membrane water. It has been proposed that the structure of the water in a given membrane is of one type only and not found in the form of "bound" and "free" portions. The nature of the membrane water changes depending on the substituent on the pyridine nitrogen atom but is not present in more than one state in any given membrane. The work conducted in this thesis extends the understanding of acid transport through anion exchange membranes and the factors affecting acid/salt selectivity. It has been determined that acid transport is largely dependent on membrane water content and independent of the degree of structure of the membrane water. The acid/salt selectivity of the membranes was found to be a result of Donnan exclusion while the increased selectivity of the alkylated membranes compared to the protonated membranes was determined to be a result of the increase in membrane water structure in the former.

abstract: Doctor of Philosophy (PhD)


title: Evaluation of modelling uncertainty and the role of model complexity in risk assessment

contributor:
Kramer, J.R.
Geology

subject: Geology Geology

abstract: Numerical simulations are used to investigate the behaviour of a system, based on a set of initial conditions and assumptions about the processes involved. The complexity of a model's structure influences its output, which in turn affects predictive performance. The confidence accorded to a model's results is directly associated with the input uncertainties propagated and transformed through the model's structure. Understanding the relationship between modelling uncertainty and model complexity is important when using numerical simulation for decision-making purposes such as environmental risk assessment. Components of uncertainty are defined by modelling error and modelling sensitivity. Modelling error is defined as the difference between a model's predictions and actual observations from the system. Modelling sensitivity is defined as the change in model output, given a change in model input. Error and sensitivity are related to complexity in different ways. More complex models have more detailed mathematical descriptions of the system being simulated. They also have less error, but greater sensitivity, due to larger numbers of inputs (degrees of freedom) and interactions within the model's structure. Therefore, error decreases and sensitivity increases, with increasing model complexity. Model utility, U, is used to select among models of different complexities. U is defined by combining evaluations of error and sensitivity into a single, quantitative characteristic. Utility is weighted by the modeller to reflect the relative importance of error and sensitivity. The uncertainty/complexity relationship is determined for two systems (a simple sorption system, and a more complex 3-dimensional groundwater tracer transport system). Moderately complex models are the most utile of those studied. For the more complex groundwater system however, all models performed equally well (no difference in error), indicating that sensitivity was the only significant contributor to utility measurements. The uncertainty/complexity relationship derived for this system indicates that all the models studied might be more complex than the system warrants, and that simpler models should be investigated. While the uncertainty/complexity relationship exists for all models, inter-disciplinary models that combine two or more discrete systems (such as environmental-economic models) are of particular interest, due to the presence of discontinuities and incompatibilities between the different model types. An inter-disciplinary model is developed, involving the integration of an input-output economic model (which describes the flow of money to and from various sectors of an economy) with a physical model that describes the environmental impact of economic activity. Simple, linear input-output models, both with and without environmental extensions, are evaluated and compared for modelling uncertainty. The effect of adding an environmental extension (and therefore changing overall model complexity) is an increase in uncertainty of model output. Uncertainty is largest at low levels of economic activity. The uncertainty/complexity relationship is a useful diagnostic tool for the purposes of selecting among models of differing complexity. The trends of error and sensitivity can define the optimal threshold of complexity, where the improvement in fit of moving to more complex models is not worth the increased sensitivity. If the optimal complexity threshold is not within the set of models studied, the results can be used to determine whether to move to more or less complicated models before repeating the process. This way, the methods can be used iteratively to arrive at the "best" model for the job.

abstract: Doctor of Philosophy (PhD)


title: The effects of air cooling on the film blowing process

contributor:
Vlachopoulos, J.
Chemical Engineering

abstract: The present work is concerned with the numerical simulation of air-cooling in the film blowing process. In many film blowing production lines, film cooling is the limiting stage in achieving higher productivity. At the same time, the cooling air stream affects the stability and the shaping of the molten bubble, as well as the morphology of the final film product. The cooling process ultimately affects both production rate and final film properties. The aerodynamics of the external cooling air and the effect of air-ring design and operational setup on the cooling efficiency were examined, using turbulent airflow simulations based on the k-[varepsilon] theory. Both single and dual air rings designs were studied. The results suggest that the air-ring airflow is dominated by the Venturi and Coanda effects and that the airflow patterns are very sensitive to minor air-ring design modifications. The variation of heat transfer coefficients along the bubble surface has been examined in detail. Additional numerical simulations were performed to evaluate the performance of a typical internal bubble cooling (IBC) configuration. Some of the limitations of typical IBC implementations were identified and attempts were made to improve the designs using the numerical simulation as an optimization tool. The results suggest that numerical simulations can be used to gain valuable insight on the IBC operation. Numerical simulation can be helpful in reducing the number of trial and error steps during the design and implementation of IBC systems. The development of sizeable temperature gradients inside the melt (in the film thickness direction) was investigated using numerical simulation. Typically, large air-cooling rates at the film surface combined with the low thermal conductivity of polymers lead to significant temperature differences between the internal and external film surfaces. The result indicate that the temperature differences in the film thickness direction may be very large and, therefore, important from a design and modeling perspective. A new methodology to calculate the film stresses is proposed, in which the temperature variations in the thickness direction and their effects on melt rheology during the blowing are taken into account. The results indicate that the film reaches the crystallization temperature having stress differences in the thickness direction. At high production rates the stress differences became more pronounced. Since the film stresses are directly related with the crystallization kinetics, it is conjectured that the final film morphology and properties are affected by the predicted stress differences in the thickness direction.

abstract: Doctor of Philosophy (PhD)


title: From Glasstown to Ferndean: Charlotte Bronte's "Jane Eyre" and the writer's search for home

contributor:
Coldwell, Joan
English

abstract: In Charlotte Brontë's fiction, the search for home is a recurring pattern that symbolizes the writer's search for her place in literary culture. Beginning with her childhood writings set in the imaginary Glasstown, this search can be traced through the Angrian saga and Charlotte Brontë's first novel, The Professor , to its optimistic resolution in Jane Eyre , with the union of the two central characters at Ferndean. The perspectives of cultural criticism and of object relations psychoanalytic theory enable this thesis to connect social and cultural meanings with the personal and individual significance of the search for home in these works. By means of this theme, Charlotte Brontë's fiction examines the question of preserving imagination and its connection to nature, a question which was also a concern of the Romantic poets. The search for home also reflects the woman writer's consciousness of the place of her work and her ideas in literary history. This thesis draws attention to the development of a characteristic narrative voice in the early writings, and to the increasing focus on female characters and the issue of creativity in the early writings and The Professor . The question of creativity is connected to representations of home in passages of heightened figurative language that symbolically explore the writer's imagination. In Jane Eyre , the narrative voice is female for the first time in Charlotte Brontë's fiction, and her search for home explores the complex relationship of nature and culture in the five homes in the novel, and in the narrator's imagination. Jane Eyre also explores the religious meaning of the search for home and develops a dialogue between patriarchal Christianity and other religious expressions, including a maternal religion related to nature, domestic rituals and the care of the body. Finally, the novel embodies, in its union of male and female characters, the woman writer's connection with Romanticism, her literary home.

abstract: Doctor of Philosophy (PhD)


title: Reading and Repetition: Individual Difference in Adult Reading Skill

contributor:
Levy, B. A.
Psychology

subject:
Behavioral Disciplines and Activities
Psychiatry and Psychology
Behavioral Disciplines and Activities

abstract: Within the last decade, the study of individual differences in reading skill has become an active area of investigation. Much of this research has been conducted with children, and has focused on selected processes hypothesized to underlie proficient reading skill. Relatively less attention has been directed toward evaluating the effects of experience in contributing to skill differences. The experiments reported in the thesis were designed to examine multiple dimensions of reading skill, and to evaluate the effects of repeated experience in two groups of readers selected on the basis of their comprehension skill. The results indicated that difference between skilled and less-skilled readers were apparent on all measures of reading. Despite these overall group differences, the less-skilled readers were at least able to benefit from repeated experience as were their more skilled peers. The results in the first experiment indicated that the less-skilled readers were poorer at word-level processing, particularly in processing unfamiliar lexical items. The second experiment examined whether this poorer processing reflected an inability to benefit from experience over repeated trials. The results indicated that the performance of both skilled and less-skilled readers improved with repeated experience. Moreover, similar gains were observed after repetition with text in Experiment 3. The results of Experiment 4 further indicated that, although the less-skilled readers appears less sensitive to higher-order dimensions of text structure when reading for meaning, their performance across specific transfer conditions indicated that they were able to used higher order information to facilitate comprehension. The results of these experiments suggest that investigation of the role of repeated experience in contributing to individual difference may clarify factors critical to the acquisition of proficient reading skills. The implications of these findings for models of reading and for future research are discussed.

abstract: Doctor of Philosophy (PhD)


title: Taking development seriously: Toward a genuinely synthetic biology

contributor:
Allen, Barry
Philosophy

subject: Philosophy Philosophy

abstract: The Human Genome Project (HGP) is nearing completion, and shortly we will have access to the complete genetic sequence of an average human being. Hopes are high that the sequence will contribute profoundly to medicine in particular, but also to our understanding of our evolutionary past. Of course, detractors have long insisted that because the HGP represents a victory for formalism in biology, determining the function of DNA sequences will remain an outstanding problem for at least the next several decades. Moreover, it is not clear that having the complete sequence will be significantly useful to biologists seeking to understand gene function in the first place. What can we expect in the postgenomic era? I reject the very idea that a complete, encapsulated sequence of a human genome is foundational to biological understanding. I set my investigation within the framework of the ancient debate between preformationists and epigenecists. I survey and conceptually analyze arguments on both sides, especially as they relate to the separation of genetics and embryology in the early part of the twentieth century. I identify modern variants of both preformationism and epigenesis, and note their reconciliation in the form of a Modern Consensus on development established after the neo-Darwinian Synthesis in biology in the 1940s. Drawing on recent work in molecular and developmental biology, I challenge the seeming intuitiveness of the Modern Consensus and its subsumption of developmental concerns under the aegis of molecular genetics. I then propose and defend an alternative synthesis of preformationism and epigenesis, and of genetics and developmental biology, according to which development (epigenesis) does not reduce to mere gene activation. I underscore the practical benefit of my perspective through a lengthy discussion of the psychiatric genetics approach to schizophrenia.

abstract: Doctor of Philosophy (PhD)


title: Workability and Strength Properties of Steel Fiber Reinforced Concrete

contributor:
Emery, John J.
Civil Engineering

subject:
Civil Engineering
Civil Engineering

abstract:
The strength properties of fiber concrete have received much attention in the past with little emphasis being placed on the workability of the composite in its fresh state. Both field and laboratory studies have identified workability of the composite as a potential problem due to fiber addition resulting in field strengths lower than those obtained in the laboratory. Therefore, in addition to studying strength properties such as fatigue, the workability of fiber concrete was considered in detail.

To obtain an optimum mix in terms of strength and workability, fiber length and concentration are of considerable importance. In the initial stages of the study, direct pull-out tests were completed to determine the optimum fiber length i.e. the fiber length just sufficient to allow full bond development under ideal conditions. The theoretical critical fiber length (1.8 cm) was found to correspond closely with the experimental optimum length of 1.27 to 1.91 cm.

Emphasis was placed on the static and fatigue flexural strengths which are important properties required for rigid pavement design. Compression, split cylinder and impact resistance strengths were also considered. The tests indicated the importance of adequate workability with respect to obtaining improved strength performance with fiber addition. An increase in fiber length and/or concentration, decreased the workability of the composite resulting in an increased number of flaws decreased compaction and decreased uniformity of fiber distribution. The relative strength increase or decrease was dependent on the predominant influence; i.e. strength loss due to increased flaw generation or strength increase due to the fiber addition. The only significant factor influencing workability besides adjusting the fiber length and/or content was with the use of super-plasticizers.

abstract: Master of Engineering (ME)


title: High speed servo control of multi-axis machine tools

contributor:
Elbestawi, M.A.
Mechanical Engineering

subject:
Mechanical Engineering
Mechanical Engineering

abstract: High Speed Servo Control of Multi-Axis Machine Tools, is concerned with maintaining tight position control at high feed rates, in the presence of disturbances generated by the cutting process. This is an important goal due to general advances in machining technologies, as well as economic pressures in specific industries. In this thesis a feed rate planning method, and servo loop control law are developed which explicitly account for the dominant machine tool servo characteristics, including actuator saturation. The feed rate planning method developed, 'Minimum Time Path Optimization' (MTPO), enables coordinated motions to be planned with near maximum utilization of servo capabilities (a reserve must be left to handle modeling error, and disturbances). The result is a significant reduction in servoing time without sacrificing path accuracy when compared to fixed acceleration and velocity limit path planning, or significantly reduced path error, when compared to fixed feed rate planning (assuming equal total time time). The servo loop level controller developed, Minimum-Time Tracking Control (MTTC), focuses on the primary sources of path error in high-speed servoing applications, specifically, limits on amplifiers, system inertia, and damping. This controller is relatively simple to compute, making it suitable for high speed servo control. MTTC's advantages are most clearly seen in its consistently superior disturbance-rejection properties. MTTC is shown to regulate steps of various sizes better (faster/less over shoot) than Generalized Predictive Control (GPC), H∞ , or Proportional Derivative (PD) controllers. It is also shown to respond more linearly in magnitude, and phase (unity gain, zero lag) to sin waves at various frequencies. A periodic observer is developed and implemented which significantly improves the rejection of cutting disturbances. Given that the major source of disturbances is the cutting process, an encoder on the spindle is used to synchronize compensation, with the disturbance. The instantaneous disturbance is estimated as the difference between the predicted acceleration, and the achieved acceleration. This estimate is then averaged as a function of spindle position, over successive spindle revolutions. A linear servo motor is constructed to investigate commutation strategies which allows each winding of a permanent magnet linear motor to be driven separately. This enables commutation strategies to be implemented which reduce the heat generated in the coils of the linear motor, increasing the continuous holding force of the motor by approximately 18%. A PC based Open Architecture Control (OAC) with soft motion control is developed which provides low level openness (All calculations including closing servo loops are performed on the PC, no special purpose motion control card is used.). This system enables the developed controllers, observers, and commutation strategies to be implemented in a cost efficient manner. It also eliminates many of the machine controller limitations which make path planning and computing difficult. Specifically, it enables the entire part path to be planned and computed in advance, stored, and executed, or played back in real-time. This eliminates the requirements of bounded execution times, and the difficulty of representing data in an intermediate form.

abstract: Doctor of Philosophy (PhD)


title: An Algorithm for the Solution of Zero-One Resource Allocation Problems

contributor:
Chakravarti, P.C.
Computation

abstract: An algorithm is developed for discrete optimization of zero-one resource allocation problems. A single constraint problem is first formulated in dynamic programming. This formulation then undergoes a number of modifications to develop the algorithm. This algorithm leads to a significant reduction in computational requirements as compared to the dynamic programming method. Three theorems and several lemmas are proved which are central in making the algorithm efficient. Different relevant features are included in the study to extend the algorithm to solve problems with more than one constraint.

abstract: Master of Science (MS)


title: Experimental and theoretical studies of oxycarbenes: Their rearrangements, homolysis and intermolecular reactions with carbon disulfide

subject: Chemistry Chemistry

abstract: The first portion of this research focuses on some of the intramolecular chemistry of oxy- and dioxycarbenes. Carbenes belonging to this group are known to fragment to radicals, both in gas and in solution phases. The computational work presented here identifies the homolysis from the singlet ground state as a viable pathway for this fragmentation. The study then concentrates on the mechanism for the homolysis of these singlet carbenes and the possibility that this apparently-simple fragmentation could involve a transition state. In accordance with models, such as Valence Bond Configuration Mixing (VBCM), transition states involving changes in bonding are said to result from destabilization due to the change from one stable ground state electronic configuration to another. The results indicated that the homolysis has an unusual conformational dependence that cannot be explained by a first approximation of the VBCM model, and is in fact attributable to a mismatch in the electronic structures of the states involved. The second portion of this work focuses on expanding the chemistry of dioxycarbenes with thiocarbonyl compounds. To this end the reaction of dimethoxycarbene with carbon disulfide (CS2 ) is examined both experimentally and computationally. The reaction gave a surprisingly complicated product, which suggested the participation of zwitterionic, dipolar and neutral intermediates. The neutral thiocarbonyl intermediates are apparently quite reactive and undergo subsequent nucleophilic attacks by dimethoxycarbene. Initial results for the reaction of diphenoxycarbene with carbon disulfide showed diphenyl thionocarbonate as the only CS2 -derived product, emphasizing the influence that exchangeable carbene substituents have on the chemistry of the zwitterionic intermediates. Dihydroxycarbene was used to model the interactions of dioxycarbenes with CS2 . The theoretical results indicate that dioxycarbenes do not undergo concerted cycloadditions to a carbon-sulfur double bond, but instead prefer nucleophilic attack at carbon to form zwitterionic intermediates, or electrophilic attack at sulfur to form ylides with an unexpected twisted geometry. Direct nucleophilic attack at carbon has also been observed computationally by previous workers for the reaction of dihydroxycarbene with carbon dioxide. These results emphasize the differences between cumulated systems and simple carbonyl systems studied in the past. Both the zwitterionic and ylide intermediates have available reaction pathways to thionocarboxylic acid (HOCSOH) and carbon monosulfide, however it was not possible to distinguish a preferred route from these results.

abstract: Doctor of Philosophy (PhD)