title: The Transformation of Agrarian Structure: A Case Study of Twifo-Hemang, Central Region, Ghana

contributor:
Howard, Rhoda E.
Sociology

subject: Sociology Sociology

abstract: This study set out to evaluate a comprehensive rural development project sponsored jointly by the state and private capital in Twifo-Hemang, a rural sub-district in the Central Region of Ghana. This oil palm production project involved the compulsory acquisition by the state and capital, of Iarge tracts of peasant Iands, and the expropriation of large numbers of direct producers from their means of production. The analysis was made on two levels. First, the immediate and long-term impact of the capitalist intrusion on agrarian structure, defined dynamically as changes in the relations of ownership, control and usufruct of land, and the changing roles of different social classes and strata in the process of production. Accordingly, the focal point of analysis was class formation and social differentiation. Second, an appraisal of the project was made in terms of its officially stated objectives, based on the existing evidence at the time this field work took place. It was found that the chances of significant increases in the incomes and improvements in the living standards among the generality of the members of society remain an unfulfilled dream contrary to the stated objectives of the development project. The thesis demonstrably supported by this work is that the large scale infiltration of new technologies and capitalist forms of production into peasant communities and the extensive appropriation of peasant lands, as occurred in this study, involve the skewing of relations to the means of production in favour of a minority who extract the surplus produced by the majority direct producers. This generates new processes of class formation and socio-economic differentiation. The position taken is that rural development planners should not only be concerned with the economic viability of projects, but they should also take account of their long-term social-structural implications within the target areas. This study does not support the ultimate decomposition thesis which regards the peasantry as a transitional phenomenon to be eventually engulfed by capitalism in underdeveloped societies. The capitalist and peasant forms of production will continue to coexist, albeit on unequal and contradictory terms, in Twifo-Hemang.

abstract: Doctor of Philosophy (PhD)


title: Optimization of In-Core Fuel Management in CANDU Nuclear Reactors

contributor:
Meneley, D.A.
Nuclear Engineering

subject:
Nuclear Engineering
Nuclear Engineering

abstract:
A numerical approach was taken to optimize in-core fuel management in CANDU reactors at equilibrium refuelling. A computer program called, OPTEX was written to obtain an optimum distribution of fuelling rates and initial fuel enrichment.

In an on-power refuelled reactor such as CANDU, depletion effects are quite localized and the global power shape results from the distribution of fuelling rates and fixed absorbers in the core. An important group of fixed absorbers, called adjuster rods, can be replaced (and modified) a number of times during the life of the reactor. The optimization process in OPTEX can be applied to the adjuster grading and the fuel management problems simultaneously, yielding the desired reactivity worth for the adjusters as well as a nominal power distribution which satisfies the design limits on the fuel.

The OPTEX approach consists in linearizing the system characteristics about points in the feasible domain of the state variables, and then using mathematical programing techniques to direct the search towards an improved state. The originality of the approach is that variational techniques, found in Generalized Perturbation Theory (GPT) or in sensitivity theory, are used to define the true gradients of the system characteristics.

The computational advantages of this approach were illustrated with two applications of the code. Using a new correlation to properly account for the effects of enrichment and axial fuelling schemes on the channel power peaking, fresh fuel enrichment was optimized in a 850 MWe CANDU reactor using Lightly Enriched Uranium (LEU) fuel. The optimum uniform enrichment was of the order of 0.91%, but was found to be sensitive to the axial fuelling schemes used. In all cases, a significant reduction of 25-30% in fuelling costs was observed.

The second problem dealt with adjuster grading in an existing 600 MW reactor. Starting with a current (nonuniform) distribution of adjuster weights, a new distribution of weights was found along with an optimized burnup distribution to yield a 3% reduction in fuelling costs while preserving the global adjuster reactivity worth.

A number of other applications were identified. In particular, it was shown how, by introducing a time-dependent GPT, the UPTEX approach could be extended to deal with the optimization of the initial core and other fuelling transients.

abstract: Doctor of Philosophy (PhD)


title: Beyond the Pale: Unsettling "Race" and Womanhood in the Novels of Harper, Hopkins, Fauset and Larsen

contributor:
Goellnicht, Donald C.
English

subject:
English Language and Literature
English Language and Literature

abstract: This dissertation proposes that writers like Frances Harper, Pauline Hopkins, Jessie Fauset, and Nella Larsen "talk out both sides" of their mouths, parodying the values of the black bourgeoisie, racialized notions of womanhood, and understandings of racial difference popular at the turn into the twentieth century. Using complex modes of address, these authors have written novels that in all likelihood were read in different directions by their white and African American readerships. I contend that these narratives would have placated their white readership with familiar forms, while simultaneously forging a sense of community with their African American readres in novels of a highly political nature which questioned and subverted definitions of womanhood and "race". These "tragic mulatta" and "passing" novels, published from 1892 to 1931 are contextualized with an analysis of three cultural efforts to consolidate turn-of-the-century American beliefs regarding race and gender: legal statutes codifying racial identities, theories of racial difference, and notions of gender identity disseminated through the cult of domesticity. Because the mulatto is neither white nor black, her ambivalent identity and experience make parody a significant trope with which these authors interrogate identity. In order to "pass" for "true women" or for white, these mulatto characters utilize and parody the very qualities designed to ensure the "purity" of whiteness and womanhood. This study argues that such parodies access an African American tradition of parodic performance that played to and on white notions of "blackness" and constructions of white identity. Moving from a consideration of such "signifyin(g)" acts as a challenge to gender and racial identities represented by heroines who pass for "true women," the study concludes with a consideration of how race, as a political category of description, is destabilized through the representation of heroines who choose to pass for white.

abstract: Doctor of Philosophy (PhD)


title: Steady State Stability Analysis of AC-DC Power Systems

contributor:
Alden, R.T.H.
Electrical and Computer Engineering

subject:
Electrical and Computer Engineering
Electrical and Computer Engineering

abstract:
This thesis presents a comprehensive approach for the steady state stability analysis of AC-DC power systems. A new method is presented for the evaluation of the system state matrix which is then used to determine system stability and develop new algorithms for the stability analysis and control of large power systems.

The method exploits the powerful features of the Component Connection Method for power system modelling and overcomes the disadvantages of the earlier methods. The state matrix is formulated from two separate sets of equations. One set models the component subsystems whereas the other defines the interconnection between the subsystems. The main advantage of this is the great flexibility provided in the modelling of the power system components. As long as the input-output quantities are fixed the modelling complexity of the subsystems may be changed without affecting the interconnection equation. A compact interconnection equation has been derived relating machine voltages and currents in the presence of a multiterminal HVDC network. The subsystems retain their physical identity in this formulation and allow the derivatives of the system state matrix to be easily obtained. The power system operating point is determined by a new sequential AC-DC loadflow scheme. Any AC loadflow method can be used. The DC network is solved using the Gauss-Siedel method and any HVDC network configuration and terminals control scheme can he accommodated. The DC network solution need not be repeated and the method ensures that a feasible HVDC system operating point is selected.

A new eigenvalue tracking algorithm has been developed based on the evaluation of the sensitivity of a matrix determinant. It iteratively updates the eigenvalues following any change in the system state matrix at one-third the cost of eigenvalue computation using the QR algorithm. Used together with the proposed state matrix formulation method, it is particularly useful for identifying the modes due to any particular subsystem.

Two new methods for decentralized placement have been developed. The first method assigns the given poles among the various subsystems and the elements of the feedback gain matrix are varied to cancel the effects of the system interconnection. The second method is based on the sensitivity of a matrix determinant and solves the decentralized pole placement problem as an inverse eigenvalue problem. Both methods are easy to implement and computationally efficient.

The methods presented in this thesis have all been verified by applying them to realistic power system models. These have included a single machine infinite bus system, a three-machine AC system with six buses and nine lines and a three-machine three-terminal AC-DC system. These applications include simulation, analysis and decentralized controller design.

abstract: Doctor of Philosophy (PhD)


title: Field Simulation and Calibration in External Electro-Optic Sampling

contributor:
Conn, David R.
Electrical and Computer Engineering

abstract: Electro-optic (E-O) sampling is capable of measuring internal node response of microwave and high speed devices and circuits with minimal invasiveness up to terahertz frequency range or in the picosecond domain. Unfortunately, the accuracy of E-O sampling is still not comparable to a conventional network analyzer due to lack of a generl calibration technique. Therefore, a general and systematic calibration technique is demanded for quantitative measurement using E-O sampling. In this thesis, a full wave time domain field analysis technique, called the Finite-Difference Time-Domain (FD-TD) method, has been applied to the external E-O sampling problem. Using this theoretical simulation model, field disturbances in external E-O sampling have been investigated, calibration method of external E-O sampling developed and the optimum probing design techniques suggested. Field disturbances, (i.e. invasiveness and distortion) in external E-O sampling have been examined quantitatively, for the first time, by means of field and wave simulation. The results suggest that probes introduce little invasiveness if they are removed from contact by a finite distance which depends on dimensions of the device being tested. The sampled signal distortion introduces considerable error at high frequencies or when sub-picosecond pulses are involved. The FD-TD method has been successfully, applied, for the first time, to external E-O sampling problem and combined with electro-optic tensor to yield electro-optic response in E-O sampling. The probe transfer function has been then derived to characterize probe specifications. It provides a practical means to quantitatively investigate the operational frequency limit of any given probe. A field based calibration technique has been developed to de-embed both invasiveness and distortion using the full wave field modeling and the probe transfer function which can be found by field simulation or measurement results. It has been found that each specific robe has an intrinsic transfer function primarily determined by probe dimensions and space between the probe face and the device being tested. The impact of different probe materials, different sampling beam positions, and different probe dimensions with respect to the device being tested (i.e. the electric field orientation) has been systematically evaluated for the first time. The results provide necessary information for engineers to properly design probes and system set-up in order to achieve optimum E-O sampling results. It has been shown that LiTaO₃ probes are favored over GaAs when the sensitivity is the major concern. In contrast, GaAs probes are preferred when the accuracy in high frequencies up to several hundred gigahertz is of primary interest. In addition, sampling near the leading edge of probes is preferred in external E-O sampling to minimize the distortion induced in the measured results. The research conducted in this thesis can be straightforwardly extended to direct and hybrid E-O sampling problems. Further research and development will lead this field based calibration technique in E-O sampling to more general devices such as microwaves monolithic circuits (MMICs).

abstract: Doctor of Philosophy (PhD)


title: Mechanisms of polyomavirus transformation of the mouse mammary gland

contributor:
Muller, W. J.
Biology

subject: Biology Biology

abstract: Polyomavirus infection of newborn rodents results in the rapid induction of tumor formation in a number of tissues. One of the prominent target organs for Polyomavirus-mediated transformation is the mammary gland. The transforming potential of Polyomavirus (PyV) resides in the cellular expression of three tumor antigens (large, middle, and small) immediately following viral absorption. Due to the potent transforming ability of these T antigens in the mouse mammary gland, and given the extensive characterization of cellular proteins which interact with the various T antigens, I sought to exploit the use of these viral oncogenes to elucidate cellular proteins critical in this transformation process. To analyze the functional significance of large T antigen expression in the mouse mammary gland, I generated transgenic mice harboring the PyV LT antigen cDNA under transcriptional control of the mouse mammary tumor virus long terminal repeat (MMTV LTR). While PyV LT expression was correlated with the genesis of mammary dysplasia, the latency, frequency, and focal nature with which tumors arise suggests that PyV LT is not sufficient to induce malignant conversion of the primary mammary epithelial cell. PyV MT efficiently transforms the mouse mammary epithelium. To better elucidate which signal transduction pathways central to this process, I have generated mouse models which effectively demonstrate the in vivo role(s) of three MT-associated proteins in mammary tumorigenesis - Src, SHC, and phosphatidylinositol 3-kinase. To directly assess the effect of mammary gland-specific expression of activated c-Src, I established transgenic mice which carry a constitutively activated form of c-src under the transcriptional control of the MMTV LTR. The roles of both SHC and Pl3'K were investigated through functional inactivation of the corresponding binding sites for these proteins of PyV MT. These mutant MT isoforms were used to generate MMTV/MT Y250F and MMTV/MT Y315/22F strains respectively. Similar to PyV LT transgenic strains, Src527F, MT Y250F, and MT Y315/22F strains all were debilitated in mammary tumor formation compared to wild-type PyV MT transgenic animals.

abstract: Doctor of Philosophy (PhD)


title: Primogeniture and Primogenitor Firstborn Child and Mortuary Traditions among the Kabana (Bariai) of West New Britain, Papua New Guinea

contributor:
Counts, D.R.
Anthropology

subject: Anthropology Anthropology

abstract: Birth order is an unexceptional biological feet. The concept of primogeniture--the eleboration of ideas, beliefs, end customs pertaining to the firstborn child--is a culturaI construct, a distinct sociocultural phenomenon that requires explication. My intent is to show that where a concept of primogeniture is found, this concept has important sociocultural ramifications and theoretical consequences that have been relatively ignored by anthropologists. This dissertation provides detailed theoretical and ethnographic coverage of the significance of the concept of primogeniture among the Kabana of West New Britain, Papua New Guinea. The concept of primogeniture and the singular importance of the firstborn child in Kabana culture are explored within the context of the complex series of ceremoniaIs that Kabana parents must perform for their firstborn child. Because the firstborn child is a product of its progenitors and all firstborn ceremonials "take place on top of the dead", firstborn ceremonials overlap with and culminate in mortuary ceremonies. Firstborn child and mortuary ceremonies comprise the totality of Kanana ceremonial and provide a framework for an understanding of the Kabana view of their universe their place in it, and the principles that give order and meaning to their lives. The descriptive analysis of these ceremonials results in the accomplishment of two major objectives. The first is to explore the concept of primogeniture and explain the significance of this concept in Kabana culture and society. Secondly, the descriptive analysis of firstborn and mortuary traditions among the Kabana fills a lacuna in the ethnogrophy of Melanesia by providing a detailed study of a hitherto undescribed peopIe and their culture.

abstract: Doctor of Philosophy (PhD)


title: Neural Networks for Data Fusion

contributor:
Litva, John
Electrical and Computer Engineering

abstract: The process of data fusion may be viewed as a multi-level hierarchical inference process whose ultimate goal is to assess a mission situation and identify, localize and analyze threats. Each succeeding level of data fusion processing deals with a greater level of abstraction. The lower level is concerned solely with individual objects where sensor data are processed to derive the best estimates of current and future positions for each hypothesized object as well as provide an inference as to the identity and key attributes of the objects. With the recent proliferation and increasing sophistication of new technologies. It is recognized that the incorporation of new techniques, such as neural networks and others, will make the data fusion system more powerful in tri-service (command, control, and communications). In this thesis, optimization neural networks are investigated. A new technique of measurement data association in a multi-target radar environment is developed. The technique is based on the mean-field-theory machine and has the advantages of both the Hopfield network and the Boltzmann machine. In the technical development, three new energy functions have been created. Theoretically, the critical annealing temperature is found to determine the annealing temperature range. A convergence theorem for the mean-field-theory machine is put forward. Based on the technique, neural data association capacities have been evaluated in cases with and without clutter, taking into account different accuracies for radar measurements. New energy functions have been extended to multiple dimensional data association. A comprehensive analysis by computer simulations has demonstrated that the new technique developed here possesses high association capacity in the presence of false alarms; it can cope with track-crossing in a dense target environment. A feature-mapping neural network for centralized data fusion is presented, and its performance is compared with that of the Maximum Likelihood approach. In support of our study of multisensor data fusion for airborne target classification with artificial neural networks (ANNs), we designed a neural classifier. Multilayer perceptrons neural networks trained by back-propagation (BP) rule are discussed. In order to speed up the training or decrease the number of epoches in the learning process, both momentum and adaptive learning rate methods are used. The simulation results show that the technique of automatic target classification using neural networks has the potential to classify targets.

abstract: Doctor of Philosophy (PhD)


title: A Proposed Solution to the Problem of Abortion

contributor:
Thomas, J.E.
Philosophy

subject: Philosophy Philosophy

abstract: In this thesis we try to develop a sense of a solution to the abortion problem which afflicts millions every year. The solution lies in seeing that the fetus, in cases of forces pregnancy, may be aborted in order to allow a woman to retain control over her body. But all that the right of the woman consists in is the right to expel the fetus, not to kill it. According to us the fetus is a human person and may be killed only when the conditions that obtain for the killing of any other human person also obtain for the fetus. Otherwise the woman may not kill, though she may expel the fetus in cases of forced pregnancy. In cases of life-threatening pregnancy, the woman may abort to kill, as this would be a case of justified self-defensive killing.

abstract: Master of Arts (MA)


title: Synthesis and NMR Spectroscopy of Tripeptide Derived Biomolecules for Site Specific Radiopharmaceuticals

contributor:
Bell, Russell Arthur
LyneLock, Colin James
Chemistry

subject: Chemistry Chemistry

abstract: This thesis describes a bifunctional approach to the development of new, site-specific radioimaging agents. The approach taken involved covalently linking a chelate, which binds strongly to ⁹⁹ᵐTc (the most commonly used radionuclide in diagnostic medicine), to a drug, usually through a spacer chain. The biological molecule, which has a well defined receptor site in the body, is then expected to guide the labelled chelate to that receptor. The initial stages of the work entailed improving the synthesis of the diamidodithiol (DADT) chelate. This chelant is of particular interest because its technetium complex is known to be stable in vivo. Tripeptide analogues of the DADT chelate were then synthesised by the use of standard peptide coupling chemistry. The peptides were of the type mercaptoacetic acid-X-L-cysteine, where X can be any amino acid. Several variations on X (Gly, Phe, His, Ile, Ser, Met, Tyr) were synthesised to provide a series of chelates with varying solubility, coordination chemistry and sites of derivatization. The rhenium complexes of two peptides, Tr-S-Mer-L-His-S-Bn-L-Cys-OMe and Tr-S-Mer-L-Ile-S-Bn-L-Cys-OMe were prepared and characterized by NMR and the former by X-ray crystallography and NMR spectrocscopy. The reaction of rhenium with the histidine containing peptide resulted in the formation of two diastereomers while the rhenium complex of the second chelnt formed only one isomer because of the steric hindrance from the isoleucine side chain. The second phase of this work involved coupling the chelants to biomolecules. The DADT chelant was coupled to tamoxifen, a drug used in the treatment of hormone-dependent breast cancer. A total synthesis was required to conjugate the chelant to an appropriate site on tamoxifen. The desired chelate-tamoxifen species was prepared in 18 steps in 7% overall yield. The 4-hydroxy analogue of tamoxifen, with a linker arm for conjugation to a chelate was also prepared. Further development towards cancer imaging agents was accomplished by conjugating one of the tripeptide chelants, Tr-S-Mer-L-Ser-S-Bn-L-Cys, to the alkylating agen chlorambucil. The product of the 10 step synthesis (30% overll yield) was characterized by several high resolution NMR techniques.

abstract: Doctor of Philosophy (PhD)


title: Automatic Quantitative Analysis of Needle Recorded EMG Signals

contributor:
Bruin, H. de
Electrical Engineering

subject:
Electrical and Electronics
Electrical and Electronics

abstract:
A procedure for the recording and storing or EMG signals for the automatic extraction of individual motor unit rate coding and morphological information was developed. The extraction of the fate coding information is performed by the analysis of individual motor unit action potential trains (MUAPT'S), obtained by decomposing the composite EMG signal, recorded from a selective surface of a needle electrode. The morphological information is derived from the analysis of macro motor unit potentials (MUP'S). The macro MUP'S are the result of ensemble averaging the cannula recorded signal, using the individual MUAPT'S as sources of synchronizing triggers for the averaging process. A standard single fibre or macro EMG needle electrode can be used.

Signals recorded during isometric, constant or slow force varying contractions, up to 50% of the maximum voluntary contraction level, can be successfully analyzed. The number of motor units simultaneously studied, usually ranges from 3 to 5. The processing of the data, for each second of muscle contraction, can be performed by a PDP 11/34 computer in approximately one minute, with 95% accurate, rate coding information obtained. This speed and accuracy may increase the clinical use of rate coding information. The procedure also provides individual motor unit rate coding and morphological information simultaneously, allowing correlation of motor unit sizes with firing rates and identification of macro MUP'S for high threshold motor units.

abstract: Doctor of Philosophy (PhD)


title: Optimal Deployment of Controller-Detectors for the HWR System

contributor:
Trojan, O. A.
Nuclear Engineering

subject:
Nuclear Engineering
Nuclear Engineering

abstract:
A major concern in the design of control systems for nuclear power reactors is where and how many controllers and detectors are to be deployed in the reactor to satisfy design criteria. In order to answer this concern, we have developed an analytical method in which emphasis is placed on the linear regulator theory and the least square estimation theory.

This work has four areas: realization of the measure of the optimality of the controller locations in terms of feedback gain in spatial control; calculation of the static set-points to compensate the excess reactivity of the reference state evaluation of dynamic range of controllers for regulating neutron fluxes; and estimation of additional responses counteracting burnup/fuelling induced random external disturbance.

The deviations of neutron, iodine and xenon distributions from the reference states were expanded with the referenced λ-modes. The order of amplitude vector space was reduced by assumption of the dominant mode concept. Performance indices were formed with reduced state vectors and separated control functions. Pontryagin's maximum principle was applied to deterministic components and the square-root filtering to stochastic components.

Problems were finally narrowed to solve a series of the algebraic matrix Lyapunov and Riccati equations whose solutions imply a linear transformation of adjoints to state vectors.

A computer code ODZCR was developed for designing CANDU zone control systems using the above theories. Analysis of the existing 600 MWe CANDU zone control compartments in terms of their locations and numbers led to the following conclusions. The effective region for both spatial and bulk control was very limited and, hence, the current vertical compartments occupied the region most effectively: also the range of spatial control assigned to individual compartments was coincident with the spatial effective region found in the study.

Alternatively we propose a horizontal zone control system that has comparable performance with better predictability.

abstract: Doctor of Philosophy (PhD)


title: Antidopaminergic Effect of Benzodiazepines and Melatonin in Rat Striatum

contributor:
Niles, Lennard P.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: Benzodiazepines (BZ) are a class of drugs that are extensively used for their anxiolytic, anticonvulsant and sedative properties. The therapeutic actions of these drugs may be mediated through the central-type BZ receptors that are linked to the GABA receptor complex (BZ/GABA). When administered in large doses, the pineal hormone, melatonin, can interact with BZ receptors. The pharmacological actions of melatonin, similar to those listed above for BZs, appear to be mediated primarily by BZ/GABA receptors, although other BZ receptors may be involved. Recently, pharmacological doses of melatonin were found to decrease apomorphine-induced rotations in 6-hydroxydopamine lesioned rats. The main objective of this thesis was to determine the mechanism(s) underlying the antidopaminergic effect of melatonin as well as BZs using the 6-hydroxydopamine lesion model of dopaminergic supersensitivity. It was hypothesized that the antidopaminergic action of BZs and melatonin was due to the ability of these drugs to either enhance GABAergic activity (since GABA can suppress striatal dopaminergic activity) or block cyclic AMP (cAMP) production since dopamine enhances cAMP formation in the striatum. The major findings may be summarized as follows: 1) Clonazepam, a central-type BZ agonist, the melatonin blocked apomorphine-induced turning in lesioned animals; 2) intrastriatal injection of the GABA antagonist, bicuculline, caused a significant reduction in the antidopaminergic effect of clonazepam and melatonin; 3) the peripheral-type BZ antagonist, PK 11195, attenuated the antidopaminergic effect of these drugs but with much less potency than bicuculline; 4) the combination of bicuculline and PK 11195, injected directly into the striatum, completely blocked the antidopaminergic action of clonazepam or melatonin; 5) PK 11195 also blocked BZ-induced inhibition of cAMP production which is involved in striatal dopaminergic function. Therefore, in addition to a GAVAergic mechanism, inhibition of a cAMP pathway may be a secondary mechanism in the antidopaminergic action of clonazepam and melatonin. In studying the effects of BZs on the cAMP pathway, a significant increase in the inhibitory effect of diazepam on adenylate cyclase (AC) activity was observed in striatal membranes from lesioned animals. Further studies indicated that this sensitization to the inhibitory effect of diazepam on AC activity may involve upregulation of BZ receptors as well as enhanced functional coupling of these receptors to inhibitory G proteins. Taken together these findings indicate that the antidopaminergic effect of clonazepam and melatonin in lesioned animals involved at least two distinct mechanisms: 1) a predominant GABAergic action and 2) possibly the suppression of cAMP production in the striatum.

abstract: Doctor of Philosophy (PhD)


title: DROUGHTS, RAINFALL AND RURAL WATER SUPPLY IN NORTHERN NIGERIA

contributor:
Woo, Ming-Ko
Geography

subject: Geography Geography

abstract: Knowledge concerning various aspects of drought and water scarcity is required to predict, and to articulate strategies to minimize the effects of future events. This thesis investigated different aspects of droughts and rainfall variability at several time scales and described the dynamics of water supply and use in a rural village in northeastern Nigeria. The parallel existence of measured climatic records and information on famine/folklore events is utilized to calibrate the historical information against the measured data. It is shown that famines or historical droughts occurred when the cumulative deficit of rainfall fell below 1.3 times the standard deviation of the long-term mean rainfall. The study demonstrated that famine chronologies are adequate proxy for drought events, providing a means for the reconstruction of the drought/climatic history of the region. Analysis of recent changes in annual rainfall characteristics show that the series of annual rainfall and number of rain days experienced a discontinuity during the 1960's, caused largely by the decrease in the frequency of moderate to high intensity rain events. The periods prior to and after the change point are homogenous and provide an objective basis for the estimation of changes in rainfall characteristics, drought parameters and for damarcating the region into sub-zones. Rainfall variability was unaffected by the abrupt change. Furthermore, the variability is independently distributed and adequately described by the normal distribution. This allows estimates of the probability of various magnitudes of thresholds of variability. The effects of droughts and rainfall variability are most strongly felt in rural areas. Analysis of the patterns of water supply and use in a typical rural village revealed that the hydrologic system is driven by the local rainfall. Perturbations in the rains propagate through the system with short lag time between the various components. Where fadama aquifers occur, they offer a major supplement of water for six to seven months during the dry season. Under traditional systems, the pattern of water withdrawal from the fadama aquifers is designed to accommodate the diverse interests of different groups and to minimize the potential for conflict. The results contribute to our understanding of drought and water scarcity and are useful in various practical applications.

abstract: Doctor of Philosophy (PhD)


title: Targets of cyclic GMP in Blood Platelets: Photolabelling, mutagenesis and pharmacological analysis of the cyclic GMP-inhibited phosphodiesterase

contributor:
Haslam, Richard J.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: The first objective of this thesis was to investigate the targets of cyclic GMP (cGMP) action in platelets. Proteins that bind cGMP were first detected by photoaffinity labelling with [³²P]cGMP and subsequently identified by molecular, pharmacological and immunological criteria. Since cGMP was already known to exert major effects in platelets through the cGMP-inhibited phosphodiesterase family (PDE3) (Maurice and Haslam, 1990a), an additional objective was to explore the molecular basis of the unique properties of this enzyme by cloning and mutagenesis studies. A photolabelling technique using [³²P]cGMP was modified to permit the rapid detection of cGMP-binding proteins in crude platelet extracts. Five labelled proteins (110, 80, 55, 49 and 38 kDa) were detected in platelet supernatant and four (80, 65, 49 and 38 kDa) in platelet membranes. The sensitivity of photolabelling to PDE3 inhibitors and specific immunoprecipitation established that the 110 kDa photolabelled species was a product of the PDE3 gene family. In addition, the 80 kDa species was identified as cGMP-dependent protein kinase (PKG) by similar methods. Interestingly, cyclic AMP (cAMP) greatly enhanced the labelling of the 80 kDa protein, suggesting the existence of a novel co-operative interaction between cAMP and cGMP. This study also detected a previously unknown 65 kDa cGMP-binding protein in platelet membranes. Since both cAMP and cGMP inhibited labelling of this protein, it may represent a novel target for both cyclic nucleotides in platelets, possibly a subunit of a cyclic nucleotide-gated (CNG) ion channel. The inhibitory effects of variouus compounds on the photolabelling of PDE3 were quantitated by [³²P]cGMP. Thus, concentration-dependent inhibition of photolabelling of PDE3 was observed with trequinsin (IC₅₀ = 13 ± 2 nM), lixazinone (IC₅₀ = 22 ± 4 nM), milrinone (IC₅₀ = 56 ± 12 nM), cilostamide (IC₅₀ = 70 ± 9 nM), siguazodan (IC₅₀ 117 ± 29 nM) and 3-isobutyl 1-methylxanthine (IBMX) (IC₅₀ = 3950 ± 22 nM). The effects of these phosphodiesterase inhibitors on iloproststimulated cAMP accumulation in intact platelets were also investigated. Discrepancies between the abilities of these compounds to inhibit photolabelling of PDE3 and to increase platelet cAMP accumulation are probably related to differences in the rates of entry of the individual inhibitors into the intact platelet. The general applicability of this photolabelling technique and its value in the detection of novel cGMP-binding proteins in crude cell extracts was demonstrated in rat tissues. Distinctive photolabelling patterns were observed in different rat tissues and the 110 kDa protein found in human platelets was replaced by a 115 kDa species in rat platelets. To clarify the molecular mechanisms by which cGMP and inhibitory drugs modulate PDE3 activity, an attempt was made to define the roles of different PDE3 domains in the action of the enzyme. To that end, the C-terminal half of platelet PDE3 was cloned, identified as a product of the PDE3A gene and expressed as an active enzyme in E.coli. Further deletion mutants were generated by removing either an additional 100 amino acids from the N-terminus or the 44 amino acid insert, characteristic of members of the PDE3 family, from the catalytic domain. Site-directed mutagenesis of the 44 amino acid insert was also conducted to explore the function of this region. Kinetic analysis of these mutant enzymes demonstrated that the deletion of N-terminal sequences from PDE3 was accompanied by progressively lower Km values and by an increased Vmax for cGMP relative to that for cAMP. Thus, N-terminal sequences exert modulatory effects on cGMP hydrolysis. Deletion of the 44 amino acid insert abolished enzyme activity, as did site-directed mutagenesis of putative β-turns located at the N- and C-termini of the insert. Mutation of a cluster of negatively charged residues in the insert did not have major effects on the hydrolysis of cAMP or cGMP. The results suggest that this insert is required to preserve an effective catalytic domain structure in PDE3. In conclusion, the major targets of cGMP in platelets were shown to include not only PKG, but also PDE3A and an unidentified membrane protein, possibly a CNG ion channel. This thesis has also identified some of the functionally and structurally important domains within PDE3A.

abstract: Doctor of Philosophy (PhD)


title: La Distribution et le Comportement du Bore dans la Lithosphere Oceanique

contributor:
Shaw, Denis M.
Geology

subject: Geology Geology

abstract:
De facon à mieux comprendré Ie comportement du bore en milieu oceanique, nous avons analysé des échantillons représentant les différents facies que l'on retrouve dans la lithosphère océanique pour leurs contenūs en bore (B) par A.N.A.G.P. (activation neutronique à gamma prompt). Ces échantillons consistent en 1) des basaltes frais 2) des basaltes altérés à basse temperature 3) des basaltes altérés hydrothermalement aux faciès: zéolites, schiste vert et amphibolites 4) des ultramafiques 5) des serpentinites 6) des argiles 7) des minéraux du fer (Fe). Nous avons aussi effectué des extractions liquides sur certains de ces échantillons afin de déterminer les phases minéralogiques responsables de la rétention du B.

Les basaltes frais des dorsales océaniques contiennent environ 2 p.p.m. de B. Leurs altérations à basse température provoquent un enrichissement en B qui augmente en fonction du degre d'alteration. Ainsi il existe des corrélations positives entre les contenus en B des basaltes altérés à basse temperature et des indicateurs d'altération tels que: Ie rapport Fe₂0₃/FeO et les teneurs en potassium (K), rubidium et H₂O. Un graphique des rapports K/B versus K des basaltes atteres a basse temperature, indique deux tendances qui peuvent refleter des etapes de l'alteration a basse temperature des basaltes. La premiere est caracterisee par une augmentation des teneurs en B alors que celles du K sont relativement constantes. La deuxieme est marquée par une augmentation simultanée des concentrations en B et en K. Dans les basaltes altérés à haute temperature (faciès schiste vert-amphibolite) provenant d'ophiolites, les teneurs en B sont similaires à celles des basaltes frais. Par contre, des spilites du Pelvoux (France) sont riches en B (environ 60 p.p.m.). Les ultramafiques contiennent des teneurs en B inferieures à 0.5 p.p.m. Leur serpentinisation occasionne une retention du B. En moyenne, les serpentinites contiennent 30 p.p.m. de B. II n y a pas de relation entre les teneurs en B dans ces échantillons et Ie degre de serpentinisation.

Des extractions séquentielles effectuées sur quatre basaltes altérés a basse température et deux serpentinites indiquent que dans ces échantillons Ie B est trés mobile et que les oxydes de Fe amorphe fixent des quantites importantes de B. La transformation des oxydes de Fe amorphe en mineraux du Fe provoque un reláchement du B. Ces résultats suggerent que dans ces échantillons Ie B est surtout fixé sur des sites de surface. D'autres extractions effectuées sur des spilites riches en carbonates, des serpentinites ophiolitiques et des argiles révèlent que dans ces échantillons Ie B est fortement fixé et que Ies carbonates des spilites ne contiennent pas de B.

Un examen du bilan océanique du B démontre qu'il existe un déséquilibre dans ce cycle. Afin d'établir un équilibre, il faut un apport en B autre que ceux fournis par l'érosion continentale et I'altération hydrothermale.

abstract: Doctor of Philosophy (PhD)


title: Behaviour of Thermal Density Currents in Cold Receiving Water Bodies

contributor:
Smith, A.A.
Civil Engineering

subject:
Civil Engineering
Civil Engineering

abstract:
In cold climates, temperatures higher than the ambient have been observed near the bottom of water lakes in the vicinity of thermal discharges. Concern has been expressed about the adverse effects of such abnormally warm water on the winter ecology of lake bottoms. It is expected that the existence of a density extremum in water at 4° C and the resulting nonlinear relation between density and temperature gives rise to densimetric flows which are markedly different from those in the linear range.

This thesis presents experimental and numerical investigations that give some insight into the phenomenon of the thermal bar and the manner in which it may infIuence nearshore transport processes in the vicinity of a thermal outfalI in a cold climate. The investigations are restricted to an idealized model where the lock exchange mechanism is selected due to the fact that its behaviour is close to that expected in the prototype situation.

The experimental investigation provides dramatic proof that the existence of an extremum in the density-temperature relation has a profound influence on the behaviour of densimetric flows in general and lock exchange behaviour in particular. Three zones in the vicinity of a thermal bar are clearly demonstrated viz. (i) the thermal overflow region. (ii) the thermal bar, and (iii) the thermal underflow region. The experiments provide data on the horizontal scale at which sinking takes place.

A numerical model has been constructed to develop a means of modelling the behaviour of a thermal bar at the outfall of a steam electric generating station cooling water system. The numerical model employs a finite-difference scheme where the resulting algebraic finite difference equations are soIved using an alternating direction implicit method and a sparse-matrix package. The numericaI modeI has been verified by comparing it to numerical solutions of four different cases of the idealized problem of steady laminar flow in an enclosed rectangular cavity with differentially heated end walIs. Moreover, additional acceleration techniques are introduced to improve the numerical solution procedure. The numerical model is employed to solve the actual problem of simulating lock exchange flows created between two water bodies having different temperatures around the temperature of maximum density (i .e. having temperatures above and below 4° C). The general behaviour which has been observed experimentally is also confirmed numerically. The sensitivity of the associated parameters is examined. The relative extension of the thermal bar is correlated with relevant system parameters. Difficulty was experienced in obtaining numerical results for the same (high) Rayleigh numbers as were used for the physical experiments. Despite this, an encouraging degree of consistency was observed between simulated and observed behaviour.

The important aspect of the study is to draw attention to the adverse effects of the sinking phenomenon (thermal bar), which may occur in the vicinity of man-made warm effluents as well as in natural bodies of water during the spring warming period. The study is significant in terms of the horizontaI scaIe at which sinking takes place, for the design of power station once-through-cooling water systems that must operate in cold climate winter conditions.

abstract: Doctor of Philosophy (PhD)


title: The Effect of Context on Children's Arthmetic Problem Solving

contributor:
Siegel, L.S.
Psychology

subject: Psychology Psychology

abstract: Several studies are presented which show that the way in which a child solves an arithmetic problem on a test is influenced by the nature of the other items comprising the test, the so-called "context" problems. These context effects pose a challenge to existing models of children's arithmetic problem solving which assume that children learn and are guided by internalized procedural rules or algorithms that are exclusively applied according to the characteristics of the current to-be-solved problem. Context effects are also demonstrated for arithmetic problems at grade levels 2 through 5 and a variety of systematic computational errors. For example, at grade 2 children made significantly more algorithm errors of a particular type when the target problems (2-by-1-digit subtraction fact problems - e.g. 12-4= or 14-8=) were located in a test composed of 2-digit-by-2-digit subtraction problems (e.g. 54-21=) than when Iocated in a test composed of 1-digit-by-1-digit subtraction problems (e.g. 5-4=). Studies are also presented demonstrating context effects with 2-digit-by-1-digit addition and subtraction target problems (grade 3), 2-digit-by-2-digit multiplication problems (grade 4), and 2-digit-by-1-digit division problems (grade 5). An analysis of the relationship between the problem solving strategies used to solve the context and target problems suggests an alternative view of children's arithmetic learning and problem solving. Children solve target problems by applying procedures that are similar or analogous to procedures used to solve the context problems. That is, children's arithmetic problem solving is often governed by a contextually driven analogy mechanism, similar to that proposed in some contemporary models of reading (Glushko, 1979; Kay & Marcel, 1981) and classification (Brooks, 1978). Several studies are also presented which demonstrate that children's tendencies to error in this way is dependent upon certain kinds of arithmetic training practices commonly followed in primary school arithmetic instruction: so-called "unmixed drills" in which the practice worksheets are composed entirely of problems to be solved using the same problem solving strategy.

abstract: Doctor of Philosophy (PhD)


title: SPONTANEOUS AND CATALYZED HYDROGEN SHIFTS IN RADICAL CATIONS HAVING A PHOSPHORYL OR CARBONYL GROUP

contributor:
Terlouw, Johan K.
Chemistry

subject: Chemistry Chemistry

abstract: Intermolecular and intramolecular hydrogen shifts represent a key component of a vast number of chemical reactions. This is particularly true for radical cations, whose high reactivity makes them prone to isomerization and dissociation reactions. In the context of the experimental work in this thesis, hydrogen transfers involved in both the intra-and inter-molecular isomerization of radical cations containing a phosphoryl (P=O) or carbonyl (C=O) functionality have been studied. The radical cations studied were generated in the rarefied gas-phase of the mass spectrometer by common ionization methods. Their structure and reactivity was studied by a variety of tandem mass spectrometry based techniques : mestable ion (MI) and collision-induced dissociation (CID) spectrometry, neutralization-reionization mass spectrometry (NRMS), collision induced dissociativ ionization (CIDI) spectrometry and a number of hybrid techniques, including CID/CID, NR/CID and CIDI/CID. The use of deuterium, 18-oxygen and 13-carbon labelled isotopologues and quantum chemical calculations at the CBS-QB3 level of theory formed an essential component in interpretation of the results. A single hydrogen shift can lead to the isomerization of a keto radical cation ito its thermodynamically more favourable enol isomer. However, if the isomerization of a solitary ion into its more stable counterpart involved a 1,2- or 1,3-H shift, it is often prohibited by a high energy barrier. Thus, the "keto" ion (CH₃O)₂(H)=O･⁺, ionized dimethyl phosphonate (1･⁺), does not readily isomerize into its "enol" tautomer (CH₃O)₂P-OH･⁺, ionized dimethyl phosphite (1b･⁺). Instead, 1･⁺ readily isomerizes via a 1,4-H shift to the very stable distonic ion CH₂O-(CH₃O)P(H)OH･⁺ (1a･⁺) and related ion-dipole complexes, which serve as precursors for the low energy loss of CH₂=O. In fact, in the μ timeframe ions 1･⁺ have completely isomerized into distonic ions 1a･⁺ which do not significantly communicate with their more stable enol counterpart. In contrast, an ion-molecule reaction of 1･⁺ with a benzonitrile molecule readily leads to a complete enolization. This is by virtue of a benzonitrile-catalyzed lowering of the high 1,3-H shift barrier separating the isomers 1a･⁺ and 1b･⁺. In the same vein, a facile tautomerization of the cyclic ethylene phosphonate "keto" ion [-OCH₂CH₂O-]P(H)=O･⁺ (2a･⁺) into its more stable "enol" isomer, ethylene phosphite [-OCH₂CH₂O-]P-OH･⁺ (2B･⁺), is prevented by a substantial 1,2-H shift barrier, 14 kcal/mol relative to 2a･⁺. In line with this conclusion, the collision-induced dissociation (CID) and neutralization-reionization (NR) spectra of the two isomers are charactistically different. Unlike the corresponding acyclic tautomers 1･⁺ and 1b･⁺, where the phosphonate isomer rapidly loses its structure identity by a facile distonicization, the barrier for this reaction in 2a･⁺ is prohibitively high and the cyclic distonic 1,2-H shift isomer [-OCH₂CH₂O-]P(H)=O･⁺, 2c･⁺, is not directly accessible. Thus, non-dissociating "keto" ions 2a･⁺ retain their structure identity in the μs timeframe. Here too, the interaction of 2a with a benzonitrile molecule in a chemical ionization type experiment readily yields the more stable "enol" type ion 2b･⁺. Experiments with benzonitrile-d₅ show that this reaction does not involve true proton-transport catalysis but rather a quid-pro-quo mechanism, analogous to that proposed for the benzonitrile-assisted enolization of acetamide. Hydrogen shifts are often induced when electronegative atoms such as oxygen are present in the radical cation. This trend is evident in the relatively small CH₃O-P=O･⁺ ion, which has more than fifteen stable isomers, not including rotational or conformational isomers. This ion has a fairly low heat of formation but it is not as stable as its distonic H-shift isomer CH₂O-P-OH･⁺, or its "enol" isomer CH₂=P(OH)=O･⁺, which represents the global minimum on the CH₃O₂P･⁺ potential energy-surface. Several CH₃O₂P･⁺ isomers were characterized experimentally and found to display a remarkable low energy decarbonylation reaction that requires three consecutive H-shifts. A detailed computational study revealed that the complex mechanism for this reaction involves the ion-dipole complex [O=C(H)-H・・・POH]･⁺ and the hydrogen bridged radical cation, [CH₂O・・・O=P]･⁺ as key intermediates. Characterization of the various CH₃O₂P･⁺ isomers also proved to be important in the context of differentiating the isobaric ions CH₃O₂P･⁺ and CH₅NOP⁺. Both m/z 78 ions are generated in equal abundance via dissociative electron ionization of acephate. The CH₃O₂P･⁺ component was found to consist of CH₃O-P=O･⁺ and CH₂O-P-OH･⁺, whereas the N-containing component was identified as CH₃O-P-NH₂⁺. Therefore, the recovery signal at m/z 78 in the previously reported neutralization-reionization spectrum of acephate does not demonstrate that CH₃O-P=O･⁺ has a stable neutral counterpart. Collision-induced dissociative ionization experiments on the reaction C₆H₅-P(=O)OCH₃⁺ ➝ C₆H₅⁺ + CH₃O-P=O is a stable molecule in the dilute gas-phase. The CH₃O₂P･⁺ isomer CH₃P(=O)₂･⁺ is only marginally stable but its neutral counterpart is predicted by theory to lie in a deep potential well. The stability of this elusive neutral was probed by a collision induced dissociative ionization (CIDI) experiment on the reaction (C₆H₅CH₂O)₂P(=O)CH₃･⁺ ➝ (C₇H₇O)(C₆H₅CHO)P(OH)CH₃･⁺ ➝ (C₆H₅CHO)P(=O)(OH)CH₃⁺ + C₇H₇･ ➝ C₆H₅CH-OH⁺ + CH₃-P(=O)₂ and a CIDI/CID experiment confirmed its structure identity. An enol radical cation is as a rule more stable than its keto isomer but this appears not to be true for the acetanilide ion. Its enol, C₆H₅NH(OH)=CH₂･⁺, was calculated to be higher in energy than the keto tautomer. The enol ion was found to eliminate HNCO at low internal energy and not ketene as reported previously. This HNCO loss occurs via an intriguing skeletal rearrangement, whose mechanism was explored using isotopic labelling and computational chemistry. As the ionized enol is less stable than its keto counterpart, it is not surprising that molecule-assisted enolization reactions of ionized acetanilide cannot be realized. However, the reverse process, i.e. a molecule-assisted ketonization of the enol ion, does not take place either but this may be due to the formation of unreactive encounter complexes. When a radical cation dissociates by loss of a radical, the reaction often involves a simple bond cleavage but hidden hydrogen shifts may also occur. Theory and experiment agree that the prominent loss of CH₃･ from ionized sorbic acid, CH₃CH=CHCH=CHCOOH･⁺, is not a direct bond cleavage not a hidden H-rearrangement. Instead, this dissociation is proposed to be a displacement reaction in which a very stable cyclic product ion, protonated 2H-pyran-2-one, is generated. Hydrogen shifts also feature prominently in the dissociation chemistry of even-election ions. The low energy oxonium ions CH₃CH=CH-C⁺(H)OCH₃, CH₂=CH-C⁺ (CH₃)-OCH₃, CH₂=C(CH₃)-C⁺(H)OCH₃ and CH₂=CH-CH(CH₃)-OCH₂⁺ all abundantly lose CH₂O. The chemistries of these C₅H₉O⁺ isomers are closely related but they are not identical and the distinctions become clearer when labelled analogues are examined. Elimination of CH₂O from the three C₄H₆OCH₃⁺ ions is proposed to involve a largely irreversible 1,5-H shift, from the OCH₃ group to the hydrocarbon chain, followed by a dipole-assisted 1,3-H shift to give energy-rich ion-neutral complexes of 1- or 2-methallyl cations and neutral CH₂O. which dissociate. For the CH₂=CH-CH(CH₃)OCH₂⁺ ion, the CH₂O loss is associated with a very small kinetic energy release, suggesting that it generates the most stable C₄H₇⁺ ion, 1-methallyl cation, at the thermochemical threshold. The enthalies of formation for the key ions in this study were obtained from CBS-QB3 calculations and thermochemical estimates.

abstract: Doctor of Philosophy (PhD)


title: The Relationship of Spatial and Memory Factors to Reading and Arithmetic Learning Disabilities in Children

contributor:
Siegel, L.S.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: The role of visual-spatial and short-term memory factors in reading and arithmetic disabilities was explored in 30 children with a reading disability: 41 with an arithmetic disability; and 70 who were achieving normally in reading, spelling, and arithmetic. All of the children had a PPVT-R score 80 and/or a WISC-R Block Design score 9. Percentile cut-off scores on the WRAT were used to classify the children into the three achievement or groups. The children were divided into three age groups (7-9, 10-11, 12-14) in order to study possible differences in cognitive performance between each disability group and the normal comparison group as a function of age. Two experimental arithmetic (Mixed Drill, Missing Symbols) and two experimental language tests (McGill Decoding Words and Nonwords), plus 4 visual-spatial tasks (Block Design, Rey-Osterreith CompIex Figure (Copy), Yerkes Blocks, Left-Right Orientation), and 5 short-term memory measures (Rey-Osterreith Complex Figure (Memory), Rey-Davis Form Board, Numerical Square, Digit Span, Phonemic - Confusability Rhyming and Nonrhyming Letters) were, administered to the children. The scores of the reading disabled children, compared to those of the normally achieving children in the same age category differed significantly in all three age groups on the following measures: McGill Decoding Words and Nonwords, Mixed Drill and Missing Symbols, Rey-Osterreith Complex Figure (Copy version), Digit Span, Phonemic - Confusability, and Numerical Square. In addition, the scores of the reading disabled children in the 7-9 age group on the Block Design and Rey-Osterreith (Memory version) tests, and in the 10-11 and 12-14 groups on the Rey-Davis 3-dimensional task, were significantly lower than those of the normally achieving children. There were no differences between the two achievement groups on the Yerkes Blocks and Left-Right Orientation tests. Considering the arithmetic disabled children in the 7-9 and 10-11 age groups, their scores differed significantly from those of the normally achieving children on the Yerkes Blocks test; as did those in the 10-11 and 12-14 age groups on the Block Design, Rey-Osterreith (Copy version), and Phonemic - Confusability (Rhyming letters) tasks. In addition, the groups differed significantly at the 7-9 and 12-14 age levels on the Rey-Osterreith (Memory) and Digit Span tests; and on the Rey-Davis 3-d and Numerical Square tasks at the 12-14 age level. There were no significant differences on the Left-Right Orientation test. The results suggest that while the performance of the reading disabled children in general is essentially normal on some measures of spatial visualization and spatial orientation; it is poor on other tasks measuring language, arithmetic, visual-motor skills, and short-term memory for language stimuli. In addition, only the younger (7-9) reading disabled children appear to have problems involving aspects of visual-spatial abilities (i.e., visual-perceptual, and spatial organization skills), and difficulties in memory for complex visual figures. The results pertaining to the arithmetic disabled children at all three age levels suggest that they have a problem in spatial visualization, and a complex memory difficulty which particularly involves visual materials. The data also point to a problem involving spatial organization and visual-motor skills which is evident after the age of 9. These findings highlight the importance of chronological age and developmental factors in learning disabilities research. They also point to the need to consider both the maturational lag and deficit positions in explaining the complex pattern of cognitive problems in both reading and arithmetic disabilities. In addition, the results indicate the possibility of a predominant involvement of the left cerebral hemisphere in reading disabilities, and a primary role of the right hemisphere in arithmetic disabilities.

abstract: Doctor of Philosophy (PhD)


title: The Role and Regulation of Gap Junctions in Uterine Smooth Muscle

contributor:
Garfield, Robert E.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
Regular, coordinated contractions of uterine smooth muscle are thought to facilitate the delivery of the fetus(es) at parturition. The development of synchronous activity at term follows the development of many, large gap junctions between uterine smooth muscle cells. The objectives of this thesis were to test the hypothesis that the formation of gap junctions improves direct intercellular communication between the muscle fibers and to determine whether the functional properties of the junctions are regulated. Increased intercellular communication in uterine tissues may facilitate synchronous activity during labor and the regulation of such cell-cell interactions by modulating the function of the gap junctions may participate in the control of uterine contractility during pregnancy and parturition.

A technique was developed to study the diffusion of a small radiolabelled glucose analog, 2-deoxyglucose, through small strips of myometrium. Tissues with many gap junctions from rats in labor demonstrated a significantly greater redistribution of tracer compared to muscle removed from days 17-20 pregnant and days 2-3 post partum animals not in labor which had few junctions. This movement of tracer was shown to be the result of intracellular and direct, cell-to-cell diffusion. Thus, there is evidence for improved intercellular communication in the myometrium during parturition when gap junctions are present.

The extent of intercellular communication in the parturient myometrium was reduced by elevating the intracellular concentrations of Ca⁺⁺ and cyclic AMP in the absence of a change in the extent of gap junctions. More significantly, however, reduced communication was shown in tissues exposed to specific agents which are thought to play a role in the regulation of pregnancy and parturition. Thus, in addition to providing for the increase in gap junctions in the myometrium at term, the hormonal alterations which precede and accompany labor may also regulate the functional properties of these cell-to-cell membrane channels.

abstract: Doctor of Philosophy (PhD)


title: Dietary-Induced Energy Expenditure: A Human Study

contributor:
Jones, N.L.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
Indirect calorimetry was used to examine energy expenditure at rest and dietary-induced energy expenditure in normal-weight and overweight volunteers, whose daily energy intakes were similar. The influences of exercise, exercise training, and insulin on dietary-induced energy expenditure were also assessed. At rest energy expenditure was 70.3 kcals/hour in the overweight volunteers, 7.4 kcals/ hour greater than in the normal-weight volunteers. Consumption of a mixed meal of nearly 1000 kcals elicited similar increases in energy expenditure in the normal-weight and overweight volunteers of 10.8 kcals/hour and 12.5 kcals/hour respectively. The results refute the suggestion that a deficiency in energy expenditure at rest or in dietary-induced energy expenditure could be responsible for the greater propensity towards obesity in the overweight volunteers.

When exercise preceded the meal, the oxygen debt of exercise summated with the dietary-induced energy expenditure in the normal-weight group. The post-prandial response in the overweight group was similar whether or not exercise preceded the meal, even though the metabolic response to exercise alone was not impaired in the overweight group.

Six volunteers (four normal-weight and two over-weight) completed an exercise training programme, and increased their fitness level. However, dietary-induced energy expenditure in response to the 1000 kcal meal was similar before and after training.

Hyperinsulinaemia in six normal-weight, non-diabetic volunteers did not influence the post-prandial energy response, although the infusion of insulin and glucose itself elicited an obligatory increase in energy expenditure.

The work described in the thesis thus suggests that in mildly overweight individuals there is no evidence that reductions in post-prandial energy expenditure account for their excess weight, but that the lack of a further increase in post-prandial energy expenditure following exercise may do so. The results of the thesis indicate that exercise training does not alter post-prandial energy expenditure, and that hyperinsulinaemia does not influence post-prandial energy expenditure.

abstract: Doctor of Philosophy (PhD)


title: The Effects of Training on Muscle Structure and Function in the Human Triceps Surae

contributor:
MacDougall, Duncan J.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
The relationship between fibre structural adaptation to strength and endurance training and the fibre physiological adaptations to these training procedures has been unexplored in humans. Methodological difficulties in fibre identification have prevented these investigations since traditional fibre classification techniques utilize various enzymes which are inactivated during fixation for electron microscopy. However, myoglobin is unaffected by glutaraldehyde fixation.

In this study, structural and functional properties of the triceps surae were studied to determine the effects of endurance and strength training on: 1. the relationship between the fibre volume of sarcoplasmic reticulum and transverse tubules (SR) to the time to peak torque (TPT) of the isometric twitch; and 2. the relationship between fibre volume of mitochondria to muscle fatiguability. Needle biopsies were obtained from the gastrocnemii and soleus muscles and fibre types were classified for electron microscopy analysis on the basis of their myoglobin content. Electron micrographs were taken from the interior of 35 type I and 35 type II fibres of each muscle and were analyzed blindly by a stereological short-line test. Contractile properties were obtained from the isometric twitch in the triceps surae complex and separately from the gastrocnemii and soleus.

Structural and contractile properties were examined in two subject groups: 1. a cross-sectional group made up of 6 subjects each of active controls, strength athletes and endurance athletes (N=18); and 2. a longitudinal training group (N=7) whom, in a unilateral training model, exercised one leg with a strength protocol and the other leg with an endurance protocol for 16 weeks.

The results indicated that TPT was greater (p<.05) following chronic strength vs. endurance training (119.0 vs. 95.3 ms respectively) but TPT was decreased (p<.01) by 24% and 16% following short-term strength and endurance training respectively. The fibre volume of SR was not altered by strength or endurance training in either cross-sectional or longitudinal training groups. Resistance to fatigue at an absolute load was increased by 1.7 fold after short-term strength training and by 3.5 fold after short-term endurance training. Mitochondria volume was unaffected by either training protocol in the gastrocnemii but lower (p<.05) in type I fibres of the soleus after short-term strength (5.76%) vs. short-term endurance training (7.26%).

It was concluded that functional adaptation to strength or endurance training may occur independent of fibre organelle volume adaptation to these training programs.

abstract: Doctor of Philosophy (PhD)


title: Acid-Base Balance and Metabolism in Short-Term, Maximal Exercise

subject:
Medical Sciences
Medical Sciences

abstract:
The acidosis accompanying short-term maximal exercise has been quantified and the mechanisms contributing to its control examined. Maximal exercise lasting 30 s was performed on a constant-velocity cycle ergometer. In 3 subjects, acid-base changes were examined across the working quadriceps femoris muscle after arterial and femoral venous catheterisation (Part A). The acid-base changes across the inactive forearm muscle were examined in 6 subjects following arterial and deep forearm venous catheterisation. Gas exchange was measured breath-by-breath during exercise and recovery (Part B). Muscle biopsies were taken from the quadriceps femoris muscle in 6 subjects and analysed for intracellular strong ion changes using neutron activation analysis (Part C).

The intracellular acid load was due to both increased CO₂ production and strong anion production; the muscle [lactate] increased to 30 mmol/kg w.w. after 30 s exercise. The CO₂ and strong ion concentration contributed 25% and 75%, respectively, to the increase in intracellular [H⁺]. The weak acid concentration was assumed not to change during exercise and recovery. CO₂ and strong ions were removed from the intracellular fluid during recovery.

Initially CO₂ output from the muscle reduced the intracellular PCO₂; the femoral venous PCO₂ increased to 105 mm Hg. The increased CO₂ flux to the lungs increased the CO₂ elimination from the body; the CO₂ output increased to 3060 ml/min by the end of exercise. The lungs were effective in removing the excess CO₂ delivered to them as the arterial PCO₂ was less than resting levels throughout recovery. Elimination of excess CO₂ from muscle was complete by 3 min recovery.

Strong ion exchange occurred more slowly; lactate disappeared at a rate of 2 mmol/kg w.w./min. Immediately after exercise the intracellular-femoral venous [lactate] gradient was 40 mmol/l and favoured diffusion of lactate into the circulation. Approximately 55-60% of the lactate diffused from the muscle, the remaining lactate was oxidised or converted to glycogen. Lactate was taken up by the inactive forearm muscle; the v-a [lactate] difference was approximately 4.5 mmol/l. Only about 45% of the lactate taken up by the inactive tissue was oxidised, the remaining lactate was metabolised to other metabolic end points. Lactate uptake by inactive tissue reduced the anion concentration of the body and increased the strong ion difference across the inactive tissue. Recovery of acid-base balance is not complete until all the lactate has been removed from the body.

abstract: Doctor of Philosophy (PhD)


title: The Implicit Learning of Structure: Analogic and Abstractive Strategies in Artificial Grammar Learning

contributor:
Brooks, L. R.
Psychology

subject: Psychology Psychology

abstract: For years, psychologists and psycholinguists have described human learning and memory in terms of abstract knowledge structures such as grammars, orthographies, prototypes, scripts and rules. These abstractions often have been thought to be implicit, and acquired through some implicit process. Recently, some theorists have suggested that at least some of the behaviour that has been attributed to implicit, abstract knowledge may actually arise from people's memory for individual cases. In this thesis, this issue is investigated by addressing the recent claims of Arthur Reber and his associates for the rapid, implicit abstraction of artificial grammars. In a series of six experiments, subjects were trained with a sample of items generated from an artificial grammar, and then given a surprise classification test in which they were asked to sort new items with respect to grammatical status. In each experiment, it was demonstrated that what had previously been attributed to implicit abstraction of grammaticality was actually a function of the similarity between transfer items and specific training experiences. It was also shown that variations in how subjects are asked to learn the training items affects their sensitivity to the specific similarity of the transfer items rather than, as Reber and his associates had suggested, their sensitivity to the grammaticality of the items. These results are interpreted in terms of "breadth of transfer" - the degree to which subjects may generalize around their memory for specific experiences. Other results suggest that breadth of transfer is a function of the specific encoding of events, and that variables that affect the encoded similarity between events affect the likelihood of item-specific transfer. All of the results are interpreted in terms of a model of structural learning that suggests that subjects' knowledge of complex domains is represented in memory as multiple traces, and that the close relationship found in these experiments between original item learning and subsequent tests of item recognition and categorical transfer is a function of the memorial distribution of these traces. Finally, the results of post-testing questionnaires that asked the subjects to attribute the bases of their transfer decisions indicated that the subjects knowledge in these tasks is less implicit than previously suggested. In affirmation of the objective analyses of their behaviour, subjects attributed their transfer decisions primarily to the similarity between training and transfer items. The results are discussed in terms of a general framework that suggests that the knowledge underlying people's performance in complex domains consists of a mixture of episodic memory for individual instances and limited, explicit abstractions.

abstract: Doctor of Philosophy (PhD)


title: Characterization of the Herpes Simplex Virus Ribonucleotide Reductase

contributor:
Bacchetti, Silvia
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
Ribonucleotide reductase catalyzes the first unique step in DNA synthesis by reduction of all four ribonucleotides to the corresponding deoxyribonucleotides. Herpes simplex virus (HSV), which codes for at least three enzymes of DNA metabolism (thymidine kinase, DNA polymerase and DNAase) was found to induce a novel ribonucleotide reductase activity upon infection of mammalian cells. The HSV-2 induced reductase was purified essentially free of the endogenous cellular enzyme and found to differ from the cellular reductase in several of its biochemical properties, most notably in its resistance to allosteric inhibition by dTTP and dATP (Huszar and Bacchetti, 1981). In addition, a rabbit antiserum was prepared (Rl serum) which was capable of specifically immunoprecipitating the HSV-2 induced reductase, thus demonstrating that the induced and cellular enzymes could also be immunologically distinguished (Huszar et al., 1983). Further experiments established that Rl serum cross-reacted with two monoclonal antibodies, both specific for HSV-2 polypeptides of approximately 144,000 and 38,000 daltons, which were capable of either immunoprecipitating the HSV-2 induced reductase (H11 antibodies) or directly neutralizing it in solution (Bg7 antibodies) (Huszar et al., 1983).

These data demonstrate that either one or both of the HSV-2 144,000 and 38,000 dalton polypeptides are associated with viral ribonucleotide reductase activity. Based on the mapping of these polypeptides (Anderson et al., 1981; Docherty et al., 1981; Galloway et al., 1982a), these data also locate the coding sequences for at least a component of the enzyme between .56 - .60 map units on the viral genome within DNA sequences associated with cell transformation. The identification of viral DNA sequences coding for, and of viral polypeptides associated with, the HSV-2 ribonucleotide reductase will facilitate studies on the relevance of the enzyme to viral replication, latency and cell transformation.

abstract: Doctor of Philosophy (PhD)


title: The Dissociation between Tacit and Reflective Measures of Memory

contributor:
Jacoby, L.L.
Psychology

subject: Psychology Psychology

abstract:
RE-cognition - "to know again" - implies an element of awareness for remembering to occur. But is awareness a necessary condition for remembering? Research with amnesics shows that it is not. Amnesics, by definition, have a memory deficit in that they are unable to report recent prior experiences. None the less, they still display the effects of those prior encounters on their behaviour if tested in appropriate ways (e.g. Corkin, 1968; Warrington and Weiskrantz, 1970; Brooks and Baddeley, 1976). Although the amnesic does not recognize having participated in a particular task before (for example, reading inverted text - Cohen and Squire, 1980), he/she will show savings or improvement in the learning of that task on subsequent occasions when measures are employed that do not require a conscious report of the earlier event. In other words, amnesics do have memory, but are unaware of its influence.

Persons with normal memory abilities can also show evidence of memory in their actions or behaviour without coincident awareness of remembering. For example, imagine the execution of well-practiced skills, such as driving a car or typing a manuscript. These tasks require a great amount of prior knowledge in order to be performed properly, but do not seem to tax one's memory or rely on one's being aware of remembering the sequence of skills needed to be carried out.

The implication of these findings is that there can be a "dissociation" in memory between the awareness of remembering and having one's ongoing behaviour influenced by remembering. It may be that many effects of memory remain undetected, given that traditional memory research measures require the expression of deliberate interrogation and conscious retrieval of prior memory events; and consequently, ignore the investigation of tacit memory forms.

The main purpose of this dissertation is to experimentally identify, investigate and evaluate this dissociation as revealed by the memory measures. The generality of the effect and possible theoretical accounts of the effect will be explored. The first three experiments demonstrate that the dissociation can be obtained with a variety of populations and tasks. One class of measures will demonstrate with amnesics the existence of a memory influence, while another set simultaneously will deny its presence. With normal subjects, each of these measures may consistently demonstrate an effect of memory, but they will produce behavioural results which are stochastically and phenomenologically independent of one another. In Experiments Four and Five, further specification of this dissociation will be obtained by demonstrating that under certain conditions the dissociative result can be disguised or eliminated through manipulations of particular experimental variables. Finally, the results from Experiment Six provide converging evidence to suggest that the dissociation is related to the type of information that is available for processing. The relationship between the measures reflects the cognitive processes of remembering which, in fact, are dissociable.

abstract: Doctor of Philosophy (PhD)


title: Modelling Stormwater Pollutants in Hamilton, Canada

contributor:
James, W.
Civil Engineering

subject:
Civil Engineering
Civil Engineering

abstract:
The fact that considerable quantities of solids, toxic metals and hazardous contaminants are washed off urban surfaces has been well documented in recent literature.

It is generally recognised that urban runoff models predict runoff quantity quite well. However, due to lack of understanding of the various processes involved in pollutant buildup, washoff and routing and insufficient, and faulty data collection, urban runoff models depict runoff quality poorly. This research therefore attempts to introduce new concepts and algorithms, based on the physical processes involved, to improve runoff quality prediction. The problem has been segmented into three broad areas: a) pollutant buildup, b) pollutant washoff and, c) routing and fate of pollutants.

The interaction of addition and removal processes in pollutant buildup has been further disaggregated. Estimates are made of the daily mass balance of pollutants over a dry period, considering meteorological and geographical effects. Additions from atmospheric dustfall, vehicles, population and special activities; removal due to biological decay, vehicle and wind created eddies and intentional removals (street sweeping) are formulated individually. Scavenging of aerosols and gases and washoff from canopies during precipitation are also modelled and added to conventional washoff. Expressions for the impact of raindrops, shear due to overland flow, and vehicle-induced eddies are used to develop a new washoff equation which is compared to conventional washoff equations. An established pollutant routing algorithm is modified to minimise summation error. All these pollutant concentration prediction algorithms are interfaced with one of the most comprehensive models, the Storm Water Management Model Version 3 (SWMM3), preserving the runoff quantity prediction algorithms. Provision has been made for variable time steps for both runoff quantity and quality. The modified SWMM3 is called CHGQUAL in the present work. CHGQUAL was applied to the Chedoke Creek Catchment in Hamilton, Canada, for verification, calibration and validation. The pollutional parameters used in the study are suspended solids(SS), biochemical oxygen demand (BOD), total nitrogen (TKN) and total phosphorous (TP). The CHGQUAL computed pollutant concentration results were statistically compared to both SWMM3 results and observed data.

The new runoff water quality algorithms showed improved predictability for the test catchment. The CHGQUAL model can readily be applied to other catchments.

abstract: Doctor of Philosophy (PhD)


title: Landsat and Seasat data for lineament and lithologic mapping in southeastern Ontario

contributor:
Howarth, P.J.
Geography

subject: Geography Geography

abstract: The use of Landsat and Seasat data for lineament and lithologic mapping has been evaluated for a study area in southeastern Ontario. Lineaments were identified and mapped from several Landsat products (i.e. DICS CCT's and transparencies, RBV and MSS imagery) and Seasat imagery. Interpreted lineament distributions were compared visually and statistically with fault and joint distributions recorded from the geologic maps of the area. Lineaments interpreted from enhanced (linear contrast stretch and 3X3 high pass filter) DICS summer and winter imagery were compared with mapped faults for a small site within the study area. Interpreted lineament length and intersection densities were compared visually and statistically with two aspects of the economic geology of the area. Discrimination of lithologies was attempted by interpreting textures and tones found on the imagery. The results of the lineament and lithologic mapping were compared with the hypothesized tectonic history of the area. It was determined that lineaments mapped from the remotely sensed data reflect the fault distribution as interpreted from the geologic map. However, lineaments identified on DICS winter imagery best reflect the fault distributions. Identification of lineaments was easier on winter imagery than summer imagery. The two computer enhancements did not aid in the identification of lineaments. A relationship between two lineament parameters and areas of mineralization was found. Lithologic discrimination from remotely sensed imagery proved difficult, although intrusive rocks were readily identifiable, particularly in the low grade metamorphic areas. Results from both the lineament and lithologic mapping provided information which is compatible with the tectonic history of the area.

abstract: Master of Science (MS)


title: 4.3-μm TE CO₂ Laser Dynamics

contributor:
Reid, J.
Physics

subject: Physics Physics

abstract:
This thesis describes a detailed study of the dynamics of the 4.3-μm CO₂ laser. Pulsed laser action at 4.3-μm its achieved by using a 10.4-μm sequence CO₂ laser to optically pump CO₂ molecules which have been excited in a discharge. Quantitative data regarding the processes involved in 4.3-μm lasing are presented, and techniques for optimization of performance are described. Single-line output energies of 15 mJ/pulse and peak powers of 100 kW/pulse are obtained using a conventional transversely-excited (TE) CO₂ discharge 88 cm in length. Furthermore, it is shown that pulse energies are scalable to several hundred millijoules.

The construction of a high power sequence CO₂ pump laser is discussed in detail. The laser utilizes an atmospheric pressure TE discharge 88-cm long and an intracavity hot CO₂ cell. Output energies of up to 6 J/pulse are obtained. Other work involves the characterization of discharge-excited CO₂ and the optimization of discharge operation. Several discharge parameters are measured including mode temperatures, collision-broadened linewidths, and overlapping gain and absorption coefficients. These measurements provide accurate input data for a rate-equation model of the 4.3-μm laser.

The study of 4.3-μm dynamics involves extensive measurements of small-signal gain and energy extraction. By making quantitative comparisons between these measurements and the rate-equation model, the influence of various parameters on the operation of 4.3-μm lasers is examined. The factors which dominate the dynamics of 4.3-μm lasers are found to be the short collisional lifetime of the 4.3-μm upper laser Ievel, the degree of discharge excitation, and the presence of interfering absorptions. As a result, efficient operation is restricted to discharge pressures below 100 Torr and CO₂ contents of less than 5 percent. The conditions which optimize performance are identified, and guidelines for scaling the 4.3-μm laser to higher pulse energies are presented.

abstract: Doctor of Philosophy (PhD)


title: Modeling and Design of Photonic Crystal Waveguides and Fibers

contributor:
Huang, W. P.
Electrical and Computer Engineering

abstract: Phonetic crystal waveguides and fibers are emerging waveguides that are formed based on relatively large-scale periodic dieletric materials, also known as the photonic band-gap materials. Modeling and simulation of such waveguide structures will help to gain understanding for the modal and transmission characteristics and their dependence on the key design and operation parameters. In this dissertation, the multilayer slab and circular photonic crystal waveguides are investigated theoretically with emphasis on their modal characteristics and transmission properties relevant to broad-band telecommunication systems and networks. Key performance parameters (e.g., the modal field, the modal effective index, the group-velocity dispersion, the confinement loss, the mode effective area, as well as the confinement factor, etc.) are simulated and analyzed by using both analytical and numerical methods. For the sake of completeness, a comprehensive review of the different mathematical methods for simulation and analysis of optical waveguides in general and photonic crystal waveguides in particular is presented. The theoretical frameworks for rigorous methods such as the finite difference method and the plane wave expansion method and for approximate methods such as the effective index method and the envelope approximate method are discussed, and their merits and shortcomings in modeling and analysis of photonic crystal waveguides and fibers are examined in great detail. The one-dimensional (1D) slab photonic crystal waveguides (PCWs) are the simplest to model and analyze, yet can offer deep insight into the salient features of photonic crystal waveguides and fibers. A somewhat exhaustive study for the modal properties of 1D PCWs is carried out with the help of the rigorous transfer matrix method. Four different guiding regimes due to the total internal reflection (TIR) and the photonic band-gap (PBG) are recognized, and their unique features are revealed and discussed. Further, scope of validity and level of accuracy for two insightful approximate methods (i.e., the effective index method and the envelope approximation method) are examined in detail by comparison with the exact solutions. Furthermore, new results about the effects of the number of unit cells (i.e., layer-pairs), the layer size-to-pitch-raio, and the core thickness on the modal properties are obtained and discussed. The two-dimensional (2D) photonic crystal waveguides such as the air-hole-filled photonic crystal fibers (PCFs) find more practical applications and also much more difficult to model and analyze. In this context, the modal analyses with different theoretical frameworks such as the scalar, semi-vector, and full-vector formulations are presented and discussed with the help of the finite difference method. It is demonstrated that the vector nature of the guided modes of the PCFs needs to be considered in analyzing the modal characteristics such as the dispersion. Based on the band structure of 2D photonic crystals, modal characteristics of the PBG-PCFs and TIR-PCFs are obtained and their physical behaviors are easy to explain. Also one new parameter is proposed to judge the single-mode operation of the PCFs, and the bending loss of the PCFs is calculated by the numerical method for the first time. Furthermore, the effects of finite number of air holes and size of interstitial holes on modal properties of the PCFs are investigated. Some scaling transformations of modal properties related to the design parameters of the waveguide structures are derived. Based on the rigorous analysis model and scaling transformations for the modal properties, a general procedure for design and optimization of the PCFs with desired modal properties is proposed. In comparison with the conventional design method, the new design procedure is more efficient and can be readily automated for the purpose of design optimization. Several applications of the design procedure (e.g., the design optimization for the dispersion shifted fibers, the dispersion flattened fibers, and the dispersion compensation fibers) are demonstrated.

abstract: Doctor of Philosophy (PhD)


title: The Semiclassical Few-Body Problem

contributor:
Bhaduri, Rajat K.
Physics

subject: Physics Physics

abstract: The few-body problem has not been studied in a general context from the point of view of semiclassical periodic orbit theory. The purpose of this thesis is to give a periodic orbit analysis of the quantum mechanical few-body problem. In particular, the goal is to study two important special cases: noninteracting and weakly-interacting few-body systems. The standard Gutzwiller theory does not apply to the case of noninteracting many-body systems since the single- article energies are conserved causing the periodic orbits to occur in continuous families in phase space. The unsymmetrized few-body problem is analyzed using the formalism of Creagh and Littlejohn [33], who have studied semiclassical dynamics in the presence of continuous symmetries. The symmetrized few-body problem further requires using the formalism of Robbins [30], and it is shown how the various exchange terms of symmetrized densities of states can be understood in terms of pseudoperiodic orbits. Numerical studies of two- and three-particle systems in a fully chaotic cardioid billiard are used throughout to illustrate and test the results of the theory. For weak interactions, the Gutzwiller theory also fails. Although the continuous families are destroyed, the periodic orbits are not sufficiently isolated for the standard theory to apply. The interaction can be thought of as a symmetry-breaking perturbation, and then it is possible to apply the results of semiclassical perturbation theory as developed by Creagh [38]. The periodic orbit structure is affected by the symmetry breaking, and this can be understood through asymptotic analysis. An approximate quantization of a two-body nonscaling nonintegrable system is achieved, although explicit quantization of nonintegrable systems is generally not possible. Issues related to the convergence of periodic orbit expansions arise in several places. The convergence of a two-particle system in a disk billiard is explored using an amplitude ordering of the sum. Problems related to truncation and ordering are further explored using two other expansions from number theory.

abstract: Doctor of Philosophy (PhD)


title: Two-dimensional Computer Vision far Inspection and Robotics

contributor:
Kitai, R.
Electrical and Computer Engineering

abstract:
The thesis concerns binary vision for non-contact inspection and robotics applications in flexible manufacturing. Two-dimensional silhouettes of three-dimensional objects are processed to measure a number of features including area, perimeter, circularity, maximum radius, moments, and number of holes. This information is then used to identify and locate randomly positioned objects to provide visual feedback for part acquisition by an industrial robot or inspection tasks that might include checking dimensional tolerances, verification of hole placement, and the like.

Silhouettes are encoded in the system as a linked list of "vertex points" representing changes of direction on the contour. An algorithm and data structures for extraction of vertex points from a raster-scanned binary image have been developed. The method operates sequentially and no restrictions are imposed on the number or topology of silhouettes in each frame. Several existing contour tracing algorithms are reviewed; the new algorithm is shown to offer considerable improvement in execution time at the expense of a small increase in memory. It is also demonstrated that vertex point approximations use significantly fewer points than run-length segment representations.

System implementation is based on a 232 x 240 CID camera, an 8086/8087 single-board microcomputer, and two custom-built boards. The architecture features a multiple bus configuration designed for high speed, parallel operation of dedicated modules: grey-level histogram generation and binary image acquisition are at video-rates. The complete software is in EPROM, and includes feature extraction for recognition and location of silhouettes encoded as vertex point lists, a data base for prototype objects and a comprehensive command set.

The software also includes communication with a PUMA 600 robot via a serial interface as well as extensions to its VAL language; in this way the robot accesses visual information under program control. An example is given of parts sorting using the extended instruction set.

The results of a large number of statistical measurements are used to establish overall system performance.

abstract: Doctor of Philosophy (PhD)


title: Cytokine regulation of immune responses in he respiratory mucosa

contributor:
Jordana, Manel
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: Atopic asthma is immunologically-driven condition characterized by reversible bronchoconstriction and Th2-polarized eosinophilic airways inflammation. As such, the development of Th2 responses is a key step in the pathogenesis of the disease. We utilised a murine model of respiratory mucosal sensitization to examine the roles of different cytokines in the generation of polarized immune-inflammatory responses in the airways. Mice were sensitized to ovalbumin (OVA) by daily aerosol exposure in the context of airway expression of GM-CSF, resulting in a Th2-polarized eosinophilic inflammatory response in the airways, reminiscent of asthma; the addition of IL-12 to the airway microenvironment deviated this response toward the Th1 phenotype. We analyzed expression of key Th1-and Th2-associated genes in the lymph nodes during Th1- and Th2-polarized sensitization, and showed that cytokine expression compartmentalized to the respiratory tract can have a profound impact on the nature of developing immune responses in the draining lymph nodes. Next, we investigated the necessity for IL-4 during GM-CSF-driven respiratory mucosal sensitization. We analyzed a variety of Th2-associated factors, including transcription factors, cytokines, chemokine receptors, and cell surface markers, and found that IL-4 was not necessary for Th2-polarization in this model. Finally, we examined whether IL-10 played a rol in mediating Th2 polarization, and observed that mice treated with anti-IL-10 antibodies or genetically deficient in IL-10 showed impaired development of Th2-polarized immune-inflammatory responses. This research highlights the importance of the cytokine microenvironment of the airways in determining the nature of the ensuing immune-inflammatory response, and defines some of the molecular requirements for the polarization of Th responses during respiratory mucosal sensitization in vivo.

abstract: Doctor of Philosophy (PhD)


title: Interactions between Natural and Synthetic Organics in the Coagulation Process

contributor:
Woods, Donald R.
Chemical Engineering

subject:
Chemical Engineering
Chemical Engineering

abstract:
The removal of fulvic acid, the most soluble fraction of humic matter, with aluminum and polyacrylamide was investigated. The experimental conditions were similar to those usually encountered in practice. The pH ranged from 6 to 8, the aluminum dosage from 10ˉ⁵M to 0.5 x 10ˉ³ M, and the polymer concentration from 0 to 1 mg/L. The fulvic acid concentration was constant at 10 mg/L.

The removal of fulvic acid with aluminum was found to depend on the particle size of the aluminum-fulvic acid flocs. This was demonstrated by both the increased removals when filters with a pore size of 0.10 μm were used (as opposed to filters with a pore size of 0.45 μm) and the beneficial effect of the presence of nonionic polyacrylamide. The nonionic polymer promoted both the removal after settling and the removal after filtration. The latter was attributed to the flocculation of micro-colloidal particles which in the absence of the polymer passed through the pores of the filter.

Based on a three-level factorial experimental design an empirical statistical model of the removal of fulvic acid was developed. The model was based on the consideration that for a narrow operating region, the response surface may be approximated with a quadratic mathematical expression. By applying this technique the effect of the pH, aluminum dosage and polymer dosage were quantitatively modelled. A polymer dosage of 0.1 mg/L was found to be optimal because it gave the minimum cost of chemicals, for the desired high degree of removal.

Finally, the most significant factors that affected the removal of fulvic acid with aluminum, in addition to the pH, the aluminum dosage and the polymer dosage, were the calcium present in the water and the interaction of calcium with the pH. The effect of calcium was larger at pH 8 than at pH 7. The effect of the polymer properties was not as large as the effect of the calcium, with the effect of the polymer molar mass being more important than the effect of the degree of hydrolysis of the polyacrylamide.

abstract: Doctor of Philosophy (PhD)