title: Developmental Changes in Gonadotropin Releasing Hormone Neurons in the Brain of the Female Rabbit (Oryctolagus cuniculus)

contributor:
YoungLai, E.V.
Health Sciences

subject:
Medicine and Health Sciences
Medicine and Health Sciences

abstract: This thesis examined developmental changes in morphology of the GnRH neuron in the female rabbit brain during sexual maturation. In the adult virgin rabbit approximately 1,000 GnRH cells were counted in half the hypothalamus. Two morphologically distinct populations of GnRH neurons were found. Fusiform cells with relatively smooth contours (smooth) accounted for 34% of the total. Cells with irregular contours (rough) represented 64% of the immunoreactive cells counted. In a subsequent experiment GnRH cell types were quantified in rabbits treated with Tamoxifen (TAM, 10 mg/kg/day), vehicle, and pregnant mare serum (PMS, 50 IU on postnatal days (PND) 25 and 28). Sexual maturity was considered achieved when rabbits attained a body weight of 3.0 kg. The proportion of rough cells increased while the smooth cells decreased with sexual maturation. This change was advanced by PHS treatment and prevented by TAM treatment compared to controls. Sexual maturity was advanced by PMS treatment (92 PND) versus controls (108 PND) and delayed by TAM treatment (128 PND). Mean plasma estradiol was significantly (P= 0.01) elevated in PHS rabbits versus controls between PND 25 and 34 and again at PND 75 (p= 0.05). Since the total number of immunoreactive cells remained constant, it is concluded that smooth cells are transformed to rough cells. In another experiment chronic ovariectomy did not change the total number of GnRH cells counted when compared to sham operated rabbits. However, the developmental shift of smooth cells to rough cells was prevented (p<0.05) in ovariectomized rabbits. These results suggest that the developmental change in GnRH cell morphology is functionally related to puberty onset. Moreover, estradiol seems to induce these changes through indirect mechanisms. It is proposed that estradiol augments the growth neural imputs to GnRH cells.

abstract: Doctor of Philosophy (PhD)


title: Seismic Response of Telecommunications Equipment Supported on Access Floors

contributor: Civil Engineering and Engineering Mechanics

subject:
Civil Engineering
Engineering Mechanics
Civil Engineering

abstract:
Access floor systems have been widely used to support equipment in telecommunications central offices. In this thesis, the seismic response of equipment supported on access floors in telecommunications central offices is studied. There are two major issues for equipment supported on access floor under seismic condition. First, the access floor tends to amplify the motions from the building floor; as a result, the equipment supported on it is subjected to a more severe shaking than if it were supported directly on a building floor. Second, most access floor systems are designed for gravity load only. Their seismic performance depends on their lateral stiffness and strength. Such information is not generally available. The objective of the study is to address the first issue and to provide guidelines for the seismic analysis, design and qualification of equipment installed on access floors. This is achieved by a systematic study on the dynamic response of combined equipment-access floor systems by experimental and analytical approaches.

The experimental work is carried out using commercial access floors of two different floor heights and a typical switching equipment unit commonly used in telecommunications central offices as test specimens. There are three phases involved in the experimental work. First, static tests are performed to investigate the stiffness and strength properties of the access floors. Second, dynamic exploratory tests are carried out to study the dynamic characteristics of the access floors, the telecommunications equipment and the combined equipment-access floor systems. Lastly, seismic tests are performed for the equipment alone and the combined equipment-access floor systems to evaluate the effect of the access floor on the seismic response of the equipment.

Based on the observations and results of the experiment, an analytical model is developed. The reliability of the model to predict the dynamic properties and the seismic response of combined equipment-access floor systems is checked by experimental results. A parametric study is then carried out using this model to provide insight into the dynamic properties of equipment-access floor systems. The model is also used to study the seismic response of equipment supported on access floors in telecommunications central offices. Finally, design spectra for telecommunications equipment supported on access floors are generated for the purposes of seismic analysis, design and qualification.

abstract: Doctor of Philosophy (PhD)


title: CHAOTIC PREDICTION AND MODELING OF SEA CLUTTER USING NEURAL NETWORKS

contributor:
Haykin, S.
Electrical Engineering

subject:
Electrical and Electronics
Electrical and Electronics

abstract:
Radar clutter, the unwanted radar echoes, has a long history of being modeled a.s a stochastic process. The main reason for using this model is that radar clutter appears to be very random to our naked eyes. Due to this stochastic assumption, radar detection is based on statistical decision theory. More precisely, the probability distribution of noise or clutter is obtained to derive the likelihood function for making decision.

In this thesis, we try to justify the stochastic assumption of radar clutter, in particular, sea clutter. We find that assuming sea clutter as a random process uses unnecessarily high degrees of freedom. In other words, sea clutter does not have to be modeled by a random process to handle its random behavior. Using different real-life sea clutter data, we show that the random nature of sea clutter is possibly a result of the chaotic phenomenon.

After showing that sea clutter is not truely random, we then try to model sea clutter data by a deterministic dynamical system. To construct a useful model for sea clutter, we need to reconstruct the dynamics of sea clutter, and neural network is used here as a tool to achieve this purpose. Two novel neural networks are developed to reconstruct the clutter dynamics. The first one is called rational function neural network which has an unique local minimum and a rapid learning phase. The second network, which uses the idea that sea clutter can be embedded as a manifold, does not require any learning, and is very robust and accurate. Both networks have excellent performances in reconstructing the dynamics of the real-life sea clutter data.

The model for sea clutter is then used for detection of small targets in ocean environment. Now detection is no longer a statistic decision problem, but rather a process of distinguishing two different dynamical systems. One dynamical system contains trajectories for sea clutter and targets, and the other describes the motion of sea clutter only. We use the trajectory matching idea to classify different dynamical systems, and the result of detecting real-life small targets such as a waverider is very exciting.

abstract: Doctor of Philosophy (PhD)


title: Nitrate Reductase in Maize Roots: Localization and Molecular Characterization

contributor:
Oaks, Ann
Biology

subject: Biology Biology

abstract:
Nitrate reductase (NR) is the first enzyme involved in the pathway of nitrate assimilation in plants. It converts nitrate to nitrite. By including the serine protease inhibitor, chymostatin, in the extraction buffer, NR from maize (Zea mays L.) roots was stabilized in vitro. Contrary to early results, it was found in substantial amounts in the mature regions of the root. Two isozymes of NR were identified, an NADH monospecific form found predominantly in the root tip, and an NAD(P)H bispecific form which was predominant in the mature portion of the roots. Both isozymes were found to reach substantial levels of activity, approximately one-third to one-half the levels found in shoots. The levels of NR activity in both shoots and roots varied with the age of the plants and the conditions of growth. Subsequent purification and biochemical characterization of the two isozymes suggested similarities in the characteristics of the isozymes. However, the NADH form had an exceptionally high Km for NADH which suggests that the NADH:NR may not be active in the assimilatior. of nitrate as it may not be able to compete with other dehydrogenases for reductant.

A partial cDNA clone of root NR was isolated, sequenced and identified as a gene distinct from the gene which codes for NR in maize leaves. The NR in maize roots was affected in a positive manner by nitrate at the levels of activity and transcription. However, it did not appear to be affected by either a diurnal rhythm or directly by light, as was found for leaf NR. Through the use of the tissue print hybridization technique, NR mRNA was found to be expressed throughout the maize root with the exception of the root tip.

In conclusion, NR in maize roots is present in high enough amounts to account for a substantial level of nitrate reduction in the roots, suggesting that maize roots have an important role in the overall metabolism of nitrate in maize.

abstract: Doctor of Philosophy (PhD)


title: Sediment and Hydraulic Characteristics of Palmer Inlet, Prince Edward Island, Canada

contributor:
Middleton, Gerard V.
Geology

subject: Geology Geology

abstract:
In order to study the sediment and hydraulic characteristics of a small tidal inlet on the coast of the Gulf of st. Lawrence, field measurements were conducted at Palmer Inlet in 1984-1987. Data collected included continuous water level and velocity measurements at various sites, bed and suspension sediment samples, box- and tubecores, direct and indirect (echo sounding) bedform observations, and general area mapping. Historic records and wind data were also available.

The first part of the thesis presents results of analyses of field data. Inlet morphology is described and its migratory behaviour analyzed by series of airphotos and maps. Surface sediment is divided into five depositional environments. Their characteristics, including grain size, bedforms and internal structures, are described based on the relative strength of tide and wave energy. Surface and subsurface data are then used to construct a three-dimensional stratigraphic model. Three sediment units were recognized, and discussed in terms of their relationship with the Holocene transgression. Generalized vertical sequences are compared with typical models, and their differences noted. Suspended sediments, megaripples and sediment transport data were also collected. Using these data, a number of existing theories and techniques are tested. They include the Rouse equation, proposed stability fields of megaripples, and their description using a variance spectrum.

A series of numerical simulations was carried out in the second part of the thesis. Their purpose is to define the hydraulic mechanism that controls the bay tidal responses and related inlet currents. The effects of various factors were examined using idealized cases. The results show that in small tidal inlets, large intertidal sand bodies are the most important factor in distorting the tide and creating asymmetry. Overall, their presence imposes a force which retards the ebb more than the flood. The model, adjusted with measured data, is then applied to Palmer Inlet. Examples of model results are used to explain the observed tidal deformation. A stability analysis of the inlet was conducted using two existing methods, from which inlet evolution is inferred.

abstract: Doctor of Philosophy (PhD)


title: Structural Chemistry of Lead-Antimony and Lead-Bismuth Sulphides

contributor:
Brown, I.D.
Materials Science and Engineering

subject:
Materials Science and Engineering
Materials Science and Engineering

abstract:
The structures in the PbS-rich part of the Ag₂S-PbS-Bi₂S₃ system are composed of PbS-like slabs obtained by twinning the parent PbS (NaCl structure) along the (311)PbS planes. A number of phases, some new and some already encountered in mineral samples, have been found by HREM. In the observed structures the slabs 4 and 7 octahedra wide were the most common. Slabs with width of 8 and 5 octahedra were also encountered, but not those with 6 octahedra. The material was sensitive to the electron beam and the structures often decomposed to galena during the observation. Disappearance of the twin boundary was accompanied by formation of an edge dislocation.

The structures in the PbS-rich part of the PbS-Sb₂S₃ system are composed of ribbons made of back to back square pyramids and arranged in three kinds of topology thus forming three homologous series. The structures of 5 phases were determined and the cation occupancies in the ribbons show that lead atoms occupy the 8- or 7-coordinated sites where the ribbons join, edge to face, while antimony atoms prefer the 7-coordinated sites where the parallel parts of the ribbons overlap.

The observations of the topology and strength of bonding in the PbS-Sb₂S₃ structures served as basis for developing models in which the structures. built of ribbons, are bonded together in variety of ways. The model correctly predicts: 1) stability of three kinds of ribbon arrangements 2) stability limits of the structures in each homologous series 3) lead and antimony distribution in the structures.

abstract: Doctor of Philosophy (PhD)


title: Spin Fluctuations in Eliashberg Theory

contributor:
Carbotte, J.P.
Physics

subject: Physics Physics

abstract:
In this thesis, we have studied the properties of a superconductor in which there are two competing dynamical interactions. One of the interactions promotes the pairing, while the other is pair breaking. We have studied the model in the framework of Eliashberg theory for the complete range of coupling strengths. from weak coupling (BCS) to the extreme strong coupling limit. We find that there are distinctive signatures in the specific heat results that are not found in a model with no dynamical pair breaking.

The work was motivated by the fact that the parent compounds of most of the high-Tc superconductors are antiferromagnetic insulators. In the superconducting state, spin fluctuations have been observed, at least in LaSrCuO and YBaCuO. For an s-wave superconductor, spin fluctuations are pair breaking. The observed thermodynamic data are consistent with the model that we have studied.

abstract: Doctor of Philosophy (PhD)


title: The Optimal Time Path for the Liberalization of a Controlled Economy: Thoery and Simulation Results

contributor:
Denton, F.T.
Chan, K.S.
Butterfield, D.W.
Economics / Economic Policy

subject: Economics Economics

abstract: The purpose of the study is to investigate the comparative dynamic properties of processes of transition from a centrally planned economy (CPE) to one with a substantial degree of market orientation. Alternative models of a CPE with Leontief technology are defined. The authorities in the CPE are assumed in these models to have full control over output or factor prices and to set the prices so as to optimize a social welfare function that takes into account both the benefits of reform and the social costs associated with changes from the old economy to the new one. In Chapter Two, we analyze a two-sector model with only one primary input, labour. The optimal time path of some control variable (the labour share in one of the sectors, for example) is monotonic and that the discount factor plays a crucial role in determining the curvature of the path. Comparative analysis indicate that, in most cases, a parameter change will produce an intuitively reasonable effect on the optimal trajectory. Chapter Three investigates a two-sector model with both labour and capital as primary inputs, while Chapter Five analyses a three-sector model with one labor and two types of capitals as primary inputs. Simulation experiments are carried out with these models using the MINOS nonlinear optimization program. The study reveals the following: (1) A lower population growth rate yields a higher steady-state level of consumption, and a higher initial capital stock gives higher consumption over time, which may justify family planning policy in a CPE, and the controlling of investment so as to effect a rapid accumulation of capital; (2) a change in a parameter has an employment and substitution effects. The overall effect depends on the signs and relative magnitudes of the two; (3) five-ten year planning period seems to be able to provide most of the benefit of the economic reform; (4) a greater penalty for structural change will smooth the time path of production of each sector; (5) attention should be paid to the objective function, since its specification does affect the results to certain extent. Chapter Four focuses on the stability of a three-sector Leontief model with portfolio conditions imposed. Unlike a neoclassical model, there is no saddlepoint instability problem in our model, since Leontief function introduces a friction from the supply side.

abstract: Doctor of Philosophy (PhD)


title: Vinyl Chloride Polymerization

contributor:
Hamielec, Archie E.
Wood, Philip E.
Woods, Donald R.
Chemical Engineering

subject:
Chemical Engineering
Chemical Engineering

abstract:
Relevant mechanisms involved in the heterogeneous free radical polymerization of vinyl chloride have been identified including elementary chemical reactions. physical phenomena of polyvinylchloride particle formation and reactant species distributions in phases during polymerization. A comprehensive reactor model for batch and semi-batch processes has been developed on the basis of these mechanisms. The present model accounts for comprehensive elementary chemical reactions, for the effect of diffusion-controlled reactions, for the monomer and initiator distributions among phases and for radical migration between monomer and polymer phases during polymerization. Wide ranging kinetic data covering commercially significant conversion and reaction temperature ranges were measured in the present investigation to better understand the mechanisms involved and to estimate model parameters. The present model predictions are in excellent agreement with experimental data obtained in the present work and independently in other laboratories. The model allows one to predict reactor pressure development; monomer conversion histories; polymerization rates; the critical conversion at the end of two phase polymerization; the limiting conversion for polymerization at temperatures below the polyvinylchloride glassy-state transition temperature; instantaneous and accumulated molecular weight averages and distributions, and other kinetic features of vinyl chloride polymerization over temperature and conversion ranges of commercial interest.

The effect of polymerization conditions on polymer properties, especially the thermal stability of polyvinylchloride, has been elucidated. Deterioration of the thermal stability of polymer at high conversions is attributed to a decrease in monomer concentration. The secondary reactions which form the defect structures in polyvinylchloride are favoured at high conversions because of the increase in radical and polymer concentrations and the decrease in monomer concentration. The defect structures which are responsible for the low thermal stability of polyvinylchloride can be minimized significantly by using a semi-batch process at high conversions. Significant improvement in thermal stability of polyvinylchloride at high productivity by semi-batch processing at the monomer vapour pressure was demonstrated in the present investigation.

A novel method for monitoring monomer conversion online during the suspension polymerization of vinyl chloride was developed in the present study. This method provides an effective tool not only for vinyl chloride polymerization kinetic studies but also can be adapted for use with other monomer and comonomer systems.

abstract: Doctor of Philosophy (PhD)


title: Kinetics of Carbonitride Precipitation in Microalloyed Steels

contributor:
Kirkaldy, J.S.
Materials Engineering

abstract:
Transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) have been used to investigate the morphologies, distributions, compositions, particle size distributions and growth kinetics of niobium carbide and titanium-niobium carbonitride precipitates in steels containing low levels of Ti, Nb, C and N. The microalloyed steels were solution treated at 1390°C for 2 hr and quenched, and then aged at 1000°C and 1100ºC for various times.

The precipitates, mostly with spherical shapes for short aging times and polyhedral and cubic shapes for long aging times, were found to be not quite uniform due to preferential sites for heterogeneous nucleation. After rapid growth within the first few minutes, insignificant ripening takes place for precipitation at 1000ºC while fast coarsening occurs at 1100ºC. During the aging, only complex carbonitride precipitates of the form (Tiᵪ Nb₁₋ᵪ)(CyN₁₋y) were found among the newly nucleated and growing particles. There is a strong size dependence of particle compositions for short aging times. The youngest of these particles. which approach the size of critical nuclei. tend to be Ti-rich. Titanium nitride tends to form at very high temperatures and titanium-niobium carbides go to completion at low temperatures.

A thermodynamic model was applied to the alloy systems to predict the compositions and mole fractions of the complex carbonitrides. The calculated precipitation time-temperature (PTT) diagrams for carbonitrides exhibit a C shape for all of the steels. A model predicting the growth kinetics of carbonitrides and composition variation within the precipitates for the initial growth stage (before coarsening) has been developed based on equilibrium thermodynamics with the inclusion of capillarity and multicomponent diffusional kinetics. In this theory the precipitates in Fe-Mi-Xj austenite containing two substitutional transition metals M (Ti, Nb or V) and two interstitial elements X (C and N) have been considered. Satisfactory agreement with the experimental results has been demonstrated.

abstract: Doctor of Philosophy (PhD)


title: Polarimetric Radar for Detection of Co-operative Targets in Clutter

contributor:
Haykin, Simon
Electrical Engineering

abstract: This thesis summarizes the results of an experimental investigation into the advantages of receiver relative phase measurement, and transmitter polarization switching for the detection of co-operative polarimetric targets in ground clutter. In addition to assessing the impacts of these hardware enhancements, the investigation quantifies relative merits of linear and circular polarizations for this application. The final goal of this research is to quantify the detection performance improvements possible through both the hardware and processing enhancements described. These results will then be used to define the architecture of the next generation of polarimetric radar navigation systems. The investigation begins by reviewing the mathematical representation of polarized waves, and the ways that polarization has been exploited in past radar systems. Next, a mathematical reflectance model is developed for the proprietary trihedral twist grid reflector, and applied to predict anechoic chamber measured responses. An experimental field trip was conducted to measure this reflector and ground clutter using the National Research Council polarimetric precipitation measurement radar. The seven-dimensional radar echo measurements were described using multiple scatter plots and analyzed using the K-nearest neighbour rule pattern classification technique. The results of this analysis revealed that both transmitter polarization switching and receiver relative phase measurement should be used together, and that these two features can reduce the probability of false alarm by up to an order of magnitude without affecting probability of detection. Lastly, linear polarization was demonstrated as providing higher performance than circular polarization for the detection of tile co-operative targets in ground clutter, both using conventional amplitude detection, and also for the amplitude-correlation channel detection.

abstract: Doctor of Philosophy (PhD)


title: Advances in Free-Radical Polymerization Kinetics

contributor:
Hamielec, A.E.
Chemical Engineering

abstract:
The kinetics of free-radical polymerization with and without crosslinking have been studied both theoretically and experimentally using methyl methacrylate (MMA) and ethylene glycol dimethacrylate (EGDMA) as a model system.

The mechanisms involved in the auto-acceleration of polymerization rate due to both chain physical entanglement and/or chemical crosslinking of polymerchains have been further elucidated using on-line electron spin resonance techniques (ESR). It was found that the observed radical trapping effect is associated with the conversion rate auto-acceleration phenomenon and that there exist two radical populations during the auto-acceleration period. The polymerization system is therefore heterogeneous with respect to the radical environment. The trapped radical fraction has been estimated by both post-effect measurement of radical concentration and deconvolution of the ESR signal. Crosslinking has been found to significantly enhance auto-acceleration and radical trapping. The radical concentrations found using large concentrations of crosslinker reach levels as high as 10⁻³ molar. The stability of the radicals trapped on the polymer network has been studied at temperatures up to 180ºC to assess the potential of the so-called reactive gels for various applications.

Radical concentrations versus time were measured by ESR for the copolymerization of MMA/EGDMA over the entire ranges of monomer composition and conversion. Together with conversion measurements, this provides a set of comprehensive kinetic data suitable for the estimation of individual rate constants for propagation, termination and also the initiation efficiency. It was found that these kinetic rate constants and the initiation efficiency fall simultaneously and dramatically when the polymerization system approaches its glass state. The free-radical gelation of MMA/EGDMA system under adiabatic conditions has also been investigated. These kinetic data permits severe testing of existing kinetic gelation models and suggest the need for further effort to develop more realistic models. For the theoretical work done in this thesis. the effort was directed to the development of more realistic kinetic models. Progress has been made in the following aspects: (1) A general method was developed to acount for chain-length dependent bimolecular terminatioll ofpolymer radicals for linear chain systems. With this method, there is no need to propose the full form of the bivariate distribution function which accounts for the dependence ofthe termination constanton the chain lengthsofterminatingpolymerradicals. (2) The Tobita-Hamielec kinetic model for free-radical polymerization with crosslinking was re-examined. The governing moment equations using the pseudo-kinetic rate constant method has been derived to include gel population and extended for asymmetric divinyl monomers.Anewsemi-statistical gelationmodel wasderived. Thismodel clearly illustrates the influenceofcrosslinkdensity distributiononotheraspectsofpolymernetworkformation. Problems in post-gelation modelling were addressed and discussed in terms of further development to provide a more realistic kinetic model. (3) A comprehensive kinetic model for the chemical modification of prepolymer in reactive processing using free-radical initiator has been derived. This model equationswhen solved give the full molecularweight distribution at different degrees of chain scission, long chain branching, crosslinking and grafting (processing time, type and level of initiator and additive). A general scheme for kinetic parameter estimation bas been also suggested.

abstract: Doctor of Philosophy (PhD)


title: Biogenesis of Rat Liver Peroxisomes: Characterization of the Integral Membrane Polypeptides and Identification of a Novel 3-Ketoacyl-CoA Thiolase

contributor:
Rachubinski, R.A.
Biochemistry

subject: Biochemistry Biochemistry

abstract:
This thesis is divided into two parts, each part addressing a particular aspect of the biogenesis of rat liver peroxisomes. The first part describes the characterization of the peroxisomal integral membrane polypeptides, and the second part describes the primary structure and targeting of peroxisomal 3-ketoacyl-CoA thiolase.

In the first part, membranes were isolated from liver peroxisomes of untreated rats and rats treated with clofibrate, a hypolipidemic drug which induces peroxisomal proliferation in rodent hepatocytes. The membranes were used to raise an antiserum in rabbits that reacted with six peroxisomal integral membrane polypeptides (molecular masses 140, 69, 50, 36, 22 and 15 kDa). Treatment of rats with clofibrate caused a 4- to 10-fold induction in the 69 kDa integral membrane polypeptide, while the other integral membrane polypeptides remained unchanged or varied to a lesser extent. The anti-peroxisomal membrane serum reacted with two integral membrane polypeptides of the endoplasmic reticulum which co-migrated with the 50 kDa and 36 kDa integral membrane polypeptides of peroxisomes. Subcellular fractionations and immunoblot analyses indicated that these integral membrane polypeptides were co-localized to peroxisomes and endoplasmic reticulum. Immunoprecipitation of in vitro translation products of RNA isolated from free and membrane-bound polysomes indicated that the 22, 36, and 69 kDa integral membrane polypeptides were synthesized on free polysomes, while the 50 kDa integral membrane polypeptide was predominantly synthesized on membrane-bound polysomes. The predominant synthesis of the 50 kDa integral membrane polypeptide on membrane-bound polysomes raises interesting possibilities concerning its biosynthesis and trafficking.

3-Ketoacyl-CoA thiolase (thiolase) catalyzes the final step of the fatty acid a-oxidation pathway in peroxisomes. Thiolase is unique among rat liver peroxisomal enzymes in that it is synthesized as a precursor possessing an amino-terminal extension, which is cleaved to generate the mature enzyme. To facilitate further examination of the synthesis, intracellular transport and processing of this enzyme, cDNA recombinants encoding thiolase were selected from a λgt11 rat liver library using antiserum raised against peroxisomal thiolase. Upon sequencing several cDNA recombinants, it was revealed that there are two distinct thiolase enzymes in rat liver peroxisomes, thiolase 1 and thiolase 2. The cDNAs encoding thiolases 1 and 2 exhibited 94.6% nucleotide sequence identity and 95.4% identity at the level of deduced amino acid sequence. Interestingly, the expression of the genes encoding the two thiolases was differentially regulated. The mRNA encoding thiolase 1 was expressed at a low level in untreated rat liver and was induced greater than 10-fold upon treatment with clofibrate. In contrast, the mRNA encoding thiolase 2 appeared to be constitutively expressed in rat liver and was only slightly induced upon treatment of rats with clofibrate. The cDNA encoding peroxisomal thiolase 2 was used in in vivo targeting studies which indicated that the thiolase prepiece contains information for targeting this protein to peroxisomes.

abstract: Doctor of Philosophy (PhD)


title: Theoretical Model Development For Fluidelastlc Instability of Heat Exchanger Tube Arrays

contributor:
Weaver, D.S.
Mechanical Engineering

subject:
Mechanical Engineering
Mechanical Engineering

abstract: A study is carried out to investigate the cross-flow induced instabilIties In heat exchanger tube arrays. For this purpose. the shortcomings of the Lever and Weaver unsteady theoretical model for a single flexible tube are dealt with and the modified model is extended to a multiple flexible tube analysis. Among the significant modifications is the introduction of a decay function to take into account the decay of the perturbations. This model predicts both static and dynamic instabiIities in the transverse and longitudinal directions. It was found that a single flexible tube become tends towards divergence at high values of the mass-damping ratio. This phenomenon is associated with smaller vibration frequencies than the natural frequency of the heat exchanger tube and approaches zero (divergence) at very high mass-damping ratios. The single flexible tube model is extended to a multiple flexible tube model to investigate the effect of the motion of neighboring tubes. It was found that this effect is very important at high values of the mass-damping ratio where the instability is dominated by stiffness terms. The decay function is investigated experimentally. Velocity fluctuations are measured up to 4 tube rows upstream the Vibrating tube. The experimentally determined decay function is used to predict the critical velocities for the dynamic instability. Equations of the theoretical model are solved numerically and the agreement between the experimental data and the theoretical predictions is reasonable for all array configurations.

abstract: Doctor of Philosophy (PhD)


title: Sheaves of Orthomodular Lattices and MacNeille Completions

contributor:
Bruns, G.
Mathematics

subject: Mathematics Mathematics

abstract: Doctor of Philosophy (PhD)


title: DNA Degradation by Adenovirus in Permissive and Non-Permissive Infections

contributor:
Mak, S.
Biology

subject: Biology Biology

abstract:
The adenovirus type 2 (Ad2) lp mutants: lp3, lp5, and the Ad2 deletion mutant, dl250, all have altered early region ElB sequences which affect the encoded 19K product. Alkaline sucrose gradient analysis shows that DNA degradation occurs in permissive human (KB) cells infected by Ip3 at high temperatures (39ºC), but not at lower temperatures. This indicates a thermolabile 19K product which is altered in its ability to prevent DNA degradation. The Ip5 virus did not induce DNA degradation in KB cells at all temperatures tested, in contrast to the results from the 19K negative mutant dl250, in which extensive DNA degradation ocurred. Results showed that the Ad2 lp3 or dl250 viral yields were not drastically reduced despite the DNA degradation phenotypes. Thus the 19K product is not essential for viral production although it does inhibit intracellular DNA degradation.

The DNA degradation phenotype was also observed in wildtype Ad12 infections of the non-permissive monkey cell line, CV1. Analysis of viral specific protein and RNA expression in the Ad12 infected CV1 cells suggest that the level of EIB expression was reduced in these non-permissive cells when compared to expression in permissive (KB) cells. Expression of the other early regions was slightly reduced in the CV1 cells compared to that in Ad12 infected KB cells. Despite expression of most early regions and normal DNA replication, adenoviral late gene expression was very much reduced in CV1 cells. This may be a result of reduced amounts of E1B 55K and/or E4 products which are required for efficient: transport and translation of late viral messages.

DNA degradation was also assayed in CV1 cells infected by one of two recombinant viruses: T1227 or T2743. These viruses had Ad12 E1A, or Ad12 F1A and E1B sequences, respectively, replacing the equivalent sequences in an Ad5 virus background. The latter virus codes for a complete Ad12 19K product, the former an Ad5 19K. Degradation induced by both viruses suggests that the Ad12 E1A has a nuclease effector function which is not completely inhibited by the Ad5 19K in CV1 cells.

abstract: Doctor of Philosophy (PhD)


title: Unweaving the Rainbow: The Taboo Woman in the Poetry of Coleridge and Keats

contributor:
Goellnicht, Donald
English

subject:
English Language and Literature
English Language and Literature

abstract:
The present thesis is a study of the problematic role of the Muse figure in relation to the Romantic quest for poetic identity. In general, the Romantic quest is riddled with the problem of domesticating the wayward Muse, with whom the male quester-poet never seems to be perfectly at home. This project of domestication is doomed, however, by the "treacherous" mutability of the Muse-principle, which turns the Romantic quest into a discourse of contradiction. To illustrate this, I will examine the figural patterns of confrontation between the quester-poet and the female Muse figures in selected works by Coleridge and Keats, focusing in particular on two major poems, "Christabel" and "Lamia."

In analyzing the English poems, I will draw from various elements of Chinese culture and appropriate them to the purpose of my study. In the context of my cross-cultural reading, the Romantic Muse is a kindred spirit to the "Mysterious Female" of the Taoist Way, who clearly represents the maternal principle of transformation. The "natural" emblem of the Way is the rainbow. An analysis of the rainbow in its various and conflictual forms of signification will help unravel the Romantic myth of organic harmony. The latant tension inscribed in the individual work's figural patterns reveals, apart from the sexual polemics underlying its symbolic structure, the ideological struggle within that elusive centre of contradiction known as the human subject. The conflicting elements which drive the Romantic quester's unstable ego in diverse directions become manifest in the literary works symptomatically, in the form of linguistic discrepancies. The result of all this textual complexity is not the construction of organic wholeness (as the New critic would claim), but the unravelling of the Romantic myth of a unified self in the very process of the quest for self-identity.

abstract: Doctor of Philosophy (PhD)


title: The Pituitary Gonadotropin-Releasing Hormone (GnRH) Receptor of the Female Rabbit: Characterization and Developmental Aspects

contributor:
YoungLai, E.V.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: The aim of the present study was to characterize the pituitary GnRH binding site in the rabbit and investigate its possible role in sexual maturation of the female rabbit. A radioligand binding assay was established and the presence of specific ¹²⁵I-DAla⁶EA binding sites in the anterior pituitary gland of the rabbit was demonstrated. ¹²⁵I-DA1a⁶EA binding was saturable, specific, displaceable, reversible, correlated with increasing tissue concentrations and susceptible to physiological manipulation. Significant ¹²⁵I-DA1a⁶EA binding was not present in the rabbit ovary suggesting that GnRH or GnRH-related peptides are not directly involved in the control of luteal function of the rabbit. 12S1_DAla6EA binding indicated the presence of two binding sites in the female adult rabbit pituitary; a high affinity, low capacity site (Kd= 0.3-0.4 nM; Bmax = 100-200 fmol/mg protein) and a lower affinity, high capacity site (Kd= 30 nM; Bmax=5-8000 fmol/mg protein). Ontogeny of ¹²⁵I-DA1a⁶EA binding in the female rabbit (40 to 120 days of age) did not show a correlation between binding site number and serum LH. In addition, the net serum LH response in female rabbits to a subcutaneous injection of DA1a⁶EA (10ng, 100ng, 1μg per kg body weight) was not significantly different between animals 40, 75 and 120 days of age. This suggests that a decrease in pituitary responsiveness to GnRH is not associated with sexual maturation in the female rabbit. Results indicate that factors other than and/or in addition to GnRH binding site number, such as post-receptor events play a role in gonadotropin secretion in the female rabbit.

abstract: Doctor of Philosophy (PhD)


title: Permeation and Thermal Desorption Studies of Deuterium Diffusion and Trapping in Ion-Implanted Nickel

contributor:
Thompson, D.A.
Smeltzer, W.W.
Davies, J.A.
Materials Science and Engineering

abstract:
The interaction between hydrogen isotopes and irradiation defects in nickel is studied using Gas-phase Permeation and Thermal Desorption Analysis techniques. The work was motivated by the need for the understanding and control of tritium diffusion and trapping in structural materials of the first generation of D-T fusion reactors, as well as by the need for minimizing helium "ash" in the plasma. Major attention was given to the study of relationships between helium defect configuration and deuterium diffusion and trapping behavior.

Permeation results show that crystalline defects such as dislocation loops produce no measurable effect on deuterium permeation in the temperature range of 373 K - 573 K, whereas helium defects decrease the apparent diffusivity and, sometimes, the permeability of deuterium by several orders of magnitude, indicating a strong trapping effect for hydrogen isotopes. Thermal treatments at elevated temperatures of samples pre-implanted with helium ions resulted in a newly observed abnormal aging history dependence on deuterium diffusion and permeation behavior. The basic aspects of this abnormal behavior were examined and analyzed.

Thermal desorption technique was used to obtain additional information on helium trapping mechanisms: for examples, the effective binding energies of deuterium to helium defects consist of a distribution of values and are in the range of 0.4 - 0.6 eV with higher values observed when helium bubbles formed; the trapping efficiency decreases from> 1 to < 0.3 when the helium fluence increases from 1x10¹⁵ to 4x10¹⁷/cm²; thermal treatments of these samples resulted in a decrease in the trapping efficiency that was also dependent on the initial helium fluences. An interesting phenomenon, "H" enhancement of helium release, was observed and analyzed using the Hydrogen-Assisted Cracking model.

abstract: Doctor of Philosophy (PhD)


title: GENETIC HYPERTENSION: IN VITRO CHARACTERIZATION OF CELLULAR MEMBRANE PROPERTIES FROM SUPERIOR CERVICAL GANGLIA NEURONES FROM RAT

contributor:
Kannan, M.S.
Neuroscience

subject:
Neuroscience and Neurobiology
Neuroscience and Neurobiology

abstract:
This work intended to study cell membrane properties of cells from genetically hypertensive animals in culture. The spontaneously hypertensive rat from the Wistar-Kyoto strain (SH rats) was used as a model. Genetically related Wistar-Kyoto (WKY) and unrelated Spague-Dawley (SD) rats were used as controls. Neurones from the Superior Cervical Ganglia (SCG) were cultured in vitro, with and without target cells from the vasculature (aorta, A VSMC, and mesenteric artery, MA VSMC). Passive and active membrane electrical properties from SCG neurones and A and MA VSMC were studied with microelectrodes via injection of long-duration (400 msec.) depolarizing and hyperpolarizing square pulses of current.

Most of WKY and SD SCG neurones fired one or two action potentials upon depolarization. The majority of SH SCG neurones was found to have lost their accommodative properties and fired three or more action potentials upon depolarisation. In all strains, firing abilities were inhibited in presence of A VSMC. The firing frequencies distributions remained unchanged in SD and WKY cocultures, but was shifted to lower values in the presence of MA VSMC in SH co-cultures. Multiple firing was found to be initiated by the absence of or lack of activation of a calcium-dependent potassium channel and carried by a regenerative calcium current. This cellular dysfunction is thought to be present in all cell types in genetically hypertensive individuals, and a general framework is provided which tentatively explains the development, establishment and complex phenotype of essential hypertension.

abstract: Doctor of Philosophy (PhD)


title: Radioactive Photoreactive Fatty Acid Analogues: Synthesis, Biological Utilization and Tools for the Study of Fatty Acid Transport

contributor:
Gerber, Gerhard E.
Biochemistry

subject: Biochemistry Biochemistry

abstract:
The present study focused on the development, synthesis and investigation of the biological activity of a radioactive photoreactive homologous series of fatty acid analogues The carbene precursor m-diazirinophenol was chosen because of its known photolytic properties. In the course of its synthesis according to published procedures, it was found that chlorinated isomers were produced. The latter contributed in lowering the yield of the desired product. Addition of pyridine in the t-butyl hypochlorite oxidation step generated higher yields of the desired protected m-diazirinophenol, free of chlorine.

A synthesis of an homologous series of omega tritiated omega hydroxy fatty acids was developed based on the oxidation of commercially available olefins with catalytic amounts of OsO₄ in presence of NaIO₄ to produce the precursor semialdehydes. Reduction of the latter with [³H]NaBH₄ afforded the corresponding omega hydroxy fatty acids. Subsequently, the pure m-diazirinophenol was coupled to the omega hydroxy group to yield the corresponding radioactive photoreactive fatty acid analogues.

The photoreactive homologous series was found to be biologically active both in vitro and in vivo. Using rat liver microsomes it was possible to compare Michaelis-Menten constants with those observed for normal substrates for the production of acyl-CoA derivatives. Furthermore, these derivatives were converted to phosphatidylcholine and phosphatidylethanolamine when the corresponding lysophospholipids were present in the incubation mixture. In vivo investigations consisted of incubating L-cells, a fibroblastic cell line, in culture with the radioactive photoreactive fatty acid analogues. Analyses of the lipid fraction of these cells showed that these analogues were present mostly in phosphatidylcholine and in phosphatidylethanolamine. These phospholipids form the major components of L-cells membranes. The photolysis at 360 nm of cells grown in presence of these analogues resulted in the radioactive labelling of a large number of proteins presumed to be integral membrane proteins. In a collaborative effort, it was found that upon infection of these cells with vesicular stomatitis virus (VSV), followed by isolation and photolysis of the virions, the viral membrane glycoprotein G was intensely labelled. Prior to photolysis it was demonstrated that radioactivity attached to the G protein corresponded to the non-photolyzed fatty acid.

Use of these fatty acids as photoaffinity fatty acid analogues, permitted the identification of an Escherichia coli 30 kD membrane protein with high affinity for [11-³H]11-diazirinophenoxyundecanoate. When the photolytically labelled 30 kD protein was boiled in SDS its polyacrylamide gel electrophoresis pattern shifted and it behaved as a 43 kD protein.

Finally, attempts were made to develop a fatty acid diffusion assay consisting of encapsulating BSA inside lipid vesicles as a trapping agent. Its potential suitability as a fatty acid transport reconstitution assay is discussed.

abstract: Doctor of Philosophy (PhD)


title: Unified DC/small-signal/large-signal microwave device modeling and circuit optimization

contributor:
Bandler, John W.
Electrical and Computer Engineering

subject:
Electrical and Computer Engineering
Electrical and Computer Engineering

abstract: This thesis presents an in-depth investigation of microwave FET device modeling and unified DC, small-signal and large-signal computer-aided design of microwave circuits. Advances in microwave FET device modeling are reviewed. The physical, analytical and nonlinear empirical models and their relationship are discussed. A new integrated DC and small-signal FET model parameter extraction approach is presented which simultaneously fits the FET model responses to the DC and small-signal measurements. Detailed formulas are derived to explore the relationship between the nonlinear DC equivalent circuit and the small-signal equivalent circuit linearized at given bias points. A large-signal FET model parameter extraction approach is introduced. The power spectrum responses of the model are calculated employing the newly exploited harmonic balance (HB) technique for efficient nonlinear frequency-domain circuit simulation. State-of-the-art optimization tools are used to fit model responses to corresponding measurements. Special considerations are given to weighting factor assignment which takes into account the wide spread magnitude of the error functions in the optimization. The HB technique for nonlinear frequency domain simulation of microwave circuits is discussed. The formulations of the HB equation, its Jacobian matrix and the related discrete Fourier transformation are described. A new approach for constructing the multiport matrix especially suitable for HB based circuit optimization is presented. The theoretical background of the unified DC, small-signal and large-signal circuit simulation is investigated. Derivations of the inherent consistency between DC/small-signal simulation and general nonlinear HB simulation are presented. A novel circuit design concept is introduced which explores the seamless integration of DC/small-signal and large-signal circuit design with multi-dimensional specifications. Examples of simultaneous DC/small-signal/large-signal FET model parameter extraction and a small-signal broad-band amplifier design are given to demonstrate the concept.

abstract: Doctor of Philosophy (PhD)


title: Spatially resolved and polarization resolved electroluminescence of 1.3 μm InGaAsP semiconductor diode lasers

contributor:
Cassidy, D.T.
Engineering Physics

subject:
Engineering Physics
Other Engineering
Other Engineering

abstract: A technique for obtaining maps of the spatially-resolved and polarization-resolved electroluminescence of 1.3 μm semiconductor diode lasers has been developed. It reveals information about the strain, scattering and absorption which exist in the active region of lasers. These data have been correlated with the spectral output of the lasers, and models have been developed which explain the correlation.

abstract: Doctor of Philosophy (PhD)


title: The peripheral vision of normal children and of children treated for cataracts

contributor:
Maurer, Daphne
Psychology

subject: Psychology Psychology

abstract: I assessed the development of peripheral vision and the effects thereon of deprivation. First, I examined the visual field in 28 5-year-olds, 24 6-year-olds, 20 7-year-olds, and 16 adults using kinetic perimetry with the Goldmann perimeter and a 6.4' light of either 31.8 cd/m² or 318 cd/m². Five-year-olds saw as far superiorly as did the group of older subjects. But even at 7 years of age, children did not see as far temporally or inferiorly as did adults. When the 5-year-olds were retested at 7 years, their fields had grown and were as large as those of the original 7-year-olds. I also examined sensitivity across the field in 20 7-year-olds, 20 8-year-olds, 12 9-year-olds, and 20 adults using static perimetry with the Octopus perimeter and a 25.8' light which varied in intensity from 0 to 1000 asb. Sensitivity in the near, mid, and far periphery was adultlike by 7 years of age, with later development at 0° centrally. Children treated for dense and central cataracts were assessed identically except that the deprived eye was focused for the testing distance by a contact lens. Each deprived eye exhibited a restricted field, especially temporally, and a less sensitive field, especially at 0° centrally. More restricted fields were found for children with longer than with shorter deprivation, except superiorly, and for children with monocular than with binocular deprivation, at least for tests with the dim light. Less sensitive fields at 0° centrally were found for children with developmental than with congenital deprivation. Finally, only children with unilateral congenital deprivation exhibited larger losses at 20° nasally than at 30° temporally. Control experiments indicated that the losses of peripheral vision could be explained only partly by optical factors. The results indicate that the development of peripheral vision continues throughout childhood, at least for tests using a small stimulus. Deprivation affects peripheral vision, especially those parts of the field slowest to develop (e.g., the temporal field, 0° centrally, and the near nasal field). It is likely that the underlying pathways are not mature until after 5 years of age.

abstract: Doctor of Philosophy (PhD)


title: The development of stratification in vegetated coastal sand dunes, Sable Island, Nova Scotia

contributor:
McCann, S.B.
Geography

subject: Geography Geography

abstract: Sable Island is the emergent portion of Sable Island Bank, located on the edge of the continental shelf about 200 km from the mainland. The island is made up of wide, flat beaches, overwashed spits, brackish and freshwater ponds and vegetated and unvegetated sand dunes. The dunes are organized into a fairly continuous north ridge which is punctuated by blowouts and a less continuous south ridge which ring the island's main body and are vegetated predominantly with Ammophila breviligulata and a variety of woody species of the Shrub Heath community. The spits are covered with low hummock dunes vegetated primarily with Honkenya peploides. A description of the stratification within the dunes provides a basis for an interpretation of the processes operating throughout their history. Particular importance is attached to the role of vegetation because each plant community has an associated set of structures which are the signature of deposition within, around, and in the lee of that group of plants. These sedimentologic signatures are combined to create a sequence which describes the history of deposition in the dunes. Distinct sequences are presented for morphologically different dunes. There are two types of foredunes, which develop in place, that have their own sequence of sedimentologic signatures. Three types of dunes develop from the migration of dune ridges over an area. Of particular importance on Sable Island are the parabolic dunes which move through the body of the island on a west-northwest to east-southeast axis. The structures in the dunes can be used to help explain the surface morphology.

abstract: Doctor of Philosophy (PhD)


title: Detection of the number of signals in array signal processing

contributor:
Wong, Kon Max
Reilly, James P.
Electrical and Computer Engineering

abstract: This thesis addresses the detection problem in array signal processing in two aspects: (a) detection problems in white noise environments; (b) detection problems in unknown coloured (spatially correlated) noise environments. New criteria for determining the number of signals in both these kinds of noise environments are developed. The performance of the new methods is analyzed theoretically and is confirmed by computer simulations using Monte Carlo method. The status of the existing methods for detection in array processing are reviewed. For the white noise environment, some unfavourable characteristics of existing methods are discussed, for example, the subjective threshold setting required by the traditional threshold methods, and the rigid performance of the information theoretic criteria. A new method, namely Eigen-Threshold (ET) method is proposed and analyzed theoretically and checked by computer simulations. The new method demonstrates superiority over the existing methods by: (a) not requiring a subjective threshold setting as required by the traditional threshold methods; (b) possessing a flexible performance which can be easily controlled by a single parameter, in contrast to the rigid performance given by the information theoretic criteria. By properly choosing the control parameter, the new method gives better performance than both AIC and MDL. Because of these advantages, the new ET method is more applicable in practice than other existing methods. Besides enjoying the same merit of not requiring a subjective threshold setting, the ET method gives a quantitative controllable performance which is useful in practice, because although the asymptotic consistency argument used in information theoretic criteria and some other methods has important theoretical significants but: (a) in any practical application the sample size can only be a limited number; (b) when the sample size N is given, and a quantitative performance is desired, the asymptotic consistency argument may not make too much sense since such arguments could not give even an approximate error level except predicting whether the error rate will go to zero when N goes to infinity. For the more difficult detection problem in the case of spatially correlated noise, there has not been any satisfactory method developed so far. By assuming a banded structure for the noise covariance matrix, which is true for many engineering applications, and applying a bi-array structure combined with canonical correlation analysis, a new elegant method is developed in this thesis. The new method, called Canonical Correlation Test (CCT) method, gives a reliable, simple, theoretically sound solution to the detection problem in unknown coloured noise environments. Massive simulations have shown that the new method is extremely robust to changes in the noise spectrum. Again, the new method is characterized by a quantitatively controllable performance. To compare the new methods with the existing methods, the widely accepted AIC and MDL criteria are used for comparison purpose through out this thesis.

abstract: Doctor of Philosophy (PhD)


title: A certain kind of education: Education, culture and society in West New Britain

contributor:
Counts, David R.
Anthropology

subject: Anthropology Anthropology

abstract: This work concerns the relationship between education and development along the north coast of West New Britain Province, Papua New Guinea. Using research from three urban-oriented primary schools, I consider the way the hidden curriculum of school life is formed in relation to both social change and cultural continuity in this area of the country. Historically, formal education in Papua New Guinea has grown from a very uneven and particularistic process led by mission educators to an increasingly centralized and secularized school system under the control of provincial and federal governments. Educational policy has become increasingly tied to hopes for economic development. Many parents and students therefore view formal education as a direct route to employment in the cash economy, despite the fact that certain economic constraints have made the 'connection' between education and wage employment a tenuous one. Although the vast majority of West New Britains will continue to make their living through subsistence agriculture in village environments, the message of much of the hidden curriculum of classroom instruction is that the children in this province need to learn the forms of social organization most prevalent in wage economy relationships and the urban environment. The celebration of abstract and academic over practical knowledge, the encouragement of a competitive individualism that creates a world of 'winners' and 'losers', and the formation of authority structures that naturalize social hierarchy emphasize an overall desire for social change. A much weaker message that emphasizes cultural continuity can also be found in a secondary form of hidden curriculum in the schools. Drawing on various cultural traditions, individual teachers give some ambivalent lessons concerning gender relations, cooperative individualism, and the possibility for the dissolution of formal educational structures. Many of these secondary messages resonate with common themes from the cultural traditions of West New Britain. In this work, I use the case material from West New Britain to illustrate the importance of using hidden curriculum as a methodological focus in order to bridge micro and macro research traditions to form a more adequate theory of cultural transmission.

abstract: Doctor of Philosophy (PhD)


title: Sexualizing power in naturalism: Theodore Dreiser and Frederick Philip Grove

contributor:
Ballstadt, Carl
English

abstract: Focusing on gender relationships of power, this dissertation examines the representations of power in Dreiser's and Grove's fiction. Deeply informed by poststructuralist feminist and Faucaultian theory, this study targets those textual sites in which power and sexuality intersect: e.g. in the construction of the body, the sexual confession, the representation of women's resistance. By exploring Canadian and American naturalistic fiction during a period of social transition, this dissertation places the discussion of power relationships in a comparative context by pointing to significantly diverging American and Canadian literary perspectives on personal and intersocietal power relations.

abstract: Doctor of Philosophy (PhD)


title: Genesis of copper-precious metal sulfide deposits in the Port Coldwell alkalic complex, Ontario

contributor:
Crocket, J.H.
Geology

subject: Geology Geology

abstract: Two gabbro-hosted sulfide deposits in the Port Coldwell alkalic complex were studied to determine the most probable mode of Cu-precious metal sulfide deposition. The deposits examined are the Marathon deposit (Fleck Resources Ltd.) in the Two Duck Lake gabbro on the eastern margin of the complex, and the MacRae occurrence in the Geordie Lake gabbro located well within the complex. A magmatic origin for sulfides in the Marathon deposit is consistent with geochemical and petrographic evidence, but is inconsistent with experimental studies for equilibration of sulfide liquids with olivine and/or silicate melts. In general, the proposed sulfide liquid contains too little Ni and Ir, and possibly too much Cu. In addition, metals in the sulfide liquid are fractionated such that their geochemical behaviour becomes increasingly like that of Pd in the order Ni = Ir<

abstract: Doctor of Philosophy (PhD)


title: Rational Choice, Deliberation, and Determinism

contributor:
Najm, S.
Philosophy

subject: Philosophy Philosophy

abstract: In this thesis I attempt to show that, contrary to the arguments offered by Carl Ginet and Richard Taylor, there is nothing in the concepts of rational choice and deliberation which would make them logically inconsistent with determinism. To this end, I begin by offering my own analyses, of these and related concepts. Except for the use of criteria and standards in place of wants and desires, my analysis of rational choice is quite similar to the standard conception. In chapter three I attempt to refute Hume's theory of causation and offer my own alternative, the principle of causal entailment. In chapter four, I attempt to point out some of the implications of this view of causation for determinism in human affairs. In chapter five, I attempt to refute the arguments offered by Ginet and Taylor.

abstract: Master of Arts (MA)


title: Synthesis and Complexing Properties of Quaterenes

contributor:
Corsini, A.
Chemistry

subject: Chemistry Chemistry

abstract: Several macrocyclic ethers (quaterenes) with limited cavity sizes were synthesized and characterized by infrared, ultraviolet and mass spectroscopy. Their complexing ability with selected metal ions was investigated to examine the analytical potential of the ligands. Unfortunately, no appreciable reaction could be detected by ultraviolet and proton NMR spectroscopy and by picrate extraction. It was concluded that the quaterenes are of not much interest as analytical ligands.

abstract: Master of Science (MS)


title: On-line instrumentation for latex production

contributor:
MacGregor, J.F.
Pelton, R. H.
Chemical Engineering

abstract: The availability of fast, reproducible on-line instrumentation plays a critical role in paving the way for improvements in the productivity and product quality of industrial processes. In the polymer latex industry, one of the primary reasons for the lack of adequate instrumentation is that the traditional on-line sensors for density, viscosity, light scattering and absorption seldom respond to only one property; instead, their response is a function of many latex properties. If, however, these sensors respond differently to latex property changes, a novel approach to instrumentation is to use information from several of them to infer several quality variables simultaneously. This thesis applies this concept to two latex systems. The first is the continuous emulsion polymerization of poly(vinyl acetate). A density meter and the single wavelength UV turbidity of a diluted sample are used to track solids fraction and mean particle size on a pilot scale reactor. To sensor-latex property relationships are derived from a mechanistic understanding of the system. The standard deviation of the solids fraction measurement is 0.8% of value, for the mean diameter, it is 3%. The second process is the batch copolymerization of styrene and methyl methacrylate (MMA). Two spectrometers, covering a wavelength range from 190 nm to 1800 nm were used to predict the weight fractions of water, styrene and MMA monomer, poly(styrene), and poly(MMA). The standard deviations of the composition measurements were between 0.2 and 1.2 weight percent. The sensor-latex property relationships were arrived at by an empirical, multivariate calibration. The important implications of these results are that: (1) the number of sensors that could be considered for on-line analyzers is greatly increased; and (2) this methodology may be successful for previously intractable instrumentation problems. Also, potentially any latex property that can be measured in the laboratory can be included in the calibration, provided the property of interest has a reproducible effect on the response of the sensor.

abstract: Doctor of Philosophy (PhD)


title: Skolem sequences: Generalizations and applications

contributor:
Rosa, Alexander
Mathematics

subject: Mathematics Mathematics

abstract: In this thesis the necessary conditions for the existence of near-, hooked near-, and indecomposable Skolem sequences are found and shown to be sufficient. We show also the existence of disjoint Skolem, disjoint hooked Skolem and disjoint near-Skolem sequences. Disjoint Skolem sequences are then applied to the existence problems for disjoint cyclic Steiner and Mendelsohn triple systems. We also consider Skolem labellings of graphs: we prove that every graph with v vertices can be embedded as an induced subgraph in a Skolem labelled graph on O(v³) vertices, and show that all paths, cycles and n-windmills can be Skolem labelled or minimum hooked Skolem labelled.

abstract: Doctor of Philosophy (PhD)


title: Some applications of Eliashberg theory

contributor:
Carbotte, J.P.
Physics

subject: Physics Physics

abstract: Eliashberg theory, which was formulated assuming that the electron-phonon interaction is the mechanism for superconductivity, has been very successful in explaining the physical properties of most superconductors. Eliashberg theory is an extension of BCS theory, the original microscopic theory of superconductivity. BCS theory is recovered from Eliashberg theory in the weak electron-boson coupling limit. Recently, a new challenge to Eliashberg theory has been brought forth by the discovery of a new class of superconductors known as the high Tc oxides. As of this writing, the question of what is the superconducting mechanism for these materials is still unanswered. In this thesis, many superconducting properties have been calculated mainly in an effort to see if Eliashberg theory may still be applicable to these materials. The approach of this effort has depended on the property being studied. In this case of the critical temperature and the isotope effect, a great deal of work has been put in to fit actual experimental results, particularly for the isotope effect. We shall show that two distinct models, one with an additional electronic mechanism along with the phonons and the other with a very large coulomb repulsion, may be able to explain the experimental results. For the electronic specific heat, maxima that should not be exceeded by an Eliashberg superconductor are established for several quantities associated with this physical property. Unfortunately, some experimental values for these quantities appear to exceed these maxima. In the case of the the nuclear spin relaxation, which has not been very extensively studied in the past, we shall look at how the coherence peak in the relaxation rate can be reduced as a function of coupling strength and draw conclusions that are applicable to conventional superconductors. The behaviour of this property in the oxides is not ignored however, and some fitting of experiment including anisotrophy as well as antiferromagnetic Fermi liquid corrections is done. For the conductivity, we examine how one may extract the superconducting gap from this property, mainly as a theoretical exercise but inspired by the efforts of experimentalists who have tried to do this using optical data for the oxides. The low frequency conductivity, like the nuclear spin relaxation, should show a coherence peak in the BCS limit. We study this as a function of coupling strength, frequency and impurity concentration. The conductivity results here are contrasted with those obtained experimentally for the oxides. There are indications that a strong coupling mechanism may have difficulty explaining these experiments. Finally, we examine the phonon self-energy, mainly using a newly derived formula for this quantity written on the real frequency axis. Results from this new formula are compared with a previous formula written on the imaginary axis. In this case, the main concern here was theoretical and the experiments results for this quantity are only briefly touched on.

abstract: Doctor of Philosophy (PhD)


title: New solution algorithms for the classification problem

contributor:
Abad, Prakash L.
Business Administration

subject: Business Administration, Management, and Operations

abstract: This thesis proposes a new mixed integer programming model of the two group classification problem. A branch-and-bound procedure is designed to solve the mixed integer programming model. The proposed procedure is more efficient than recently published procedures in the literature. Three heuristics are also designed from the branch-and- bound procedure. The Three Seed and N Seed heuristics provide solutions that are "close" to the optimal solution for substantially less computational effort. This thesis also proposes a quadratic transformation method which provides a solution that is competitive with the classical quadratic discriminant analysis method.

abstract: Doctor of Philosophy (PhD)


title: Closed frame homomorphisms

contributor:
Banaschewski, Bernhard
Mathematics

subject: Mathematics Mathematics

abstract: This thesis is a systematic study of closed frame homomorphisms, which can be viewed as a natural generalization of the classical closed continuous mappings of topological spaces. Following the features of frame theory, we attempt to prove our results constructively. Various aspects of closed homomorphisms are investigated in relation to certain categorical colimits, including coequalizers, coproducts and pushouts. Another main topic is the study of perfect homomorphisms. Useful characterizations are obtained for perfect homomorphisms between regular continuous frames and between completely regular frames. The injectives in the category of completely regular frames are analysed. A condition equivalent to the Sikorski Theorem (injective = complete, for Boolean algebra) is established. As a fundamental part of the whole work, the structure of binary coproducts of frames is studied in a constructive context. Finally, the basic theory of connected congruences is developed and applied to study local connectedness of frames.

abstract: Doctor of Philosophy (PhD)


title: Study of 1-metalated-2-(trimethylsilyl)vinyl cations: An examination of the β-effect for silyl, germyl and stannyl groups

contributor:
Brook, Michael A.
Chemistry

subject: Chemistry Chemistry

abstract: The ability of silicon, germanium and tin elements (group 14) to stabilize a vinyl cation intermediate was investigated upon proton addition to metalated (trimethylsilyl)acetylene compounds to lead, after demetalation, to monometalated acetylenes. The reactions were followed by ¹H NMR spectroscopy. A bimolecular addition mechanism is obtained and nucleophilic participation in the reaction is observed. The reaction rates showed that vinyl cations are stabilized by hyperconjugation of the carbon-metal bond (β-effect) in the order of magnitude Sn (10⁸) > Ge (500) > Si (1). The magnitude of the β-effect on vinyl cation is altered to a degree by the groups born by the metal. The vinyl cations are stabilized, in a lower extent, by inductive effects of the metalated group to the electron-deficient carbon (α-effect).

abstract: Doctor of Philosophy (PhD)


title: Characterization of a constitutive heterochromatin abnormality in Roberts syndrome

contributor:
Tomkins, D.J.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: Roberts syndrome (RS) is a rare autosomal recessive developmental disorder that is characterized by severe pre- and post-natal growth retardation, tetraphocomelia and various craniofacial abnormalities. In some patients with Roberts syndrome (RS+) but not others (RS-), RS is associated with a cytogenetic abnormality which presents as an unusual "puffing" of the constitutive heterochromatin and nucleolar organizing regions. The decondensed appearance of the constitutive heterochromatin suggests an alteration in chromatin structure in RS+. Two main questions were addressed in this study; (1) are altered levels of DNA methylation associated with the constitutive heterochromatin abnormality of RS+ chromosomes and (2) is the timing of DNA replication of constitutive heterochromatin, relative to the rest of the genome, altered in RS+ lymphoblast cells? Levels of methylated cytosine residues of RS+ and RS- heterochromatin DNA, assessed using MspI and HpaII isoschizomer restriction enzyme digestion and Southern blot hybridization with a repetitive probe (D15Z1) to the heterochromatin DNA, were found to be significantly lower (p = 0.048) in RS+ fibroblast cell strains compared to control and RS- cell strains. In addition to this, D15Z1 DNA methylation levels differed significantly (p ≤ 0.05) at early and late passage in fibroblast cell strains of all three groups, suggesting that decreased levels of DNA methylation were associated with an in vitro aging effect. The chromosome replication patterns of the constitutive heterochromatin regions of chromosomes 1, 9, 16 and Y were investigated using terminal 5-bromodeoxyuridine labelling and an S phase subclassification system. A significant delay (p < 0.001 for male cell lines; p<0.05 for female cell lines) was observed in the timing of RS+ constitutive heterochromatin. These results suggest that the cytogenetic abnormality of the constitutive heterochromatin of RS+ cells is associated with alterations in DNA conformation and synthesis.

abstract: Doctor of Philosophy (PhD)


title: MML estimators and robust classification and linear regression procedures

contributor:
Balakrishnan, Narayanaswamy
Mathematics

subject: Mathematics Mathematics

abstract:
Statistical classification and regression are two widely used statistical techniques. The former is concerned with the problem of classifying an object of unknown origin into one of two or more distinct groups of populations on the basis of observations made on it. The broad appeal of regression techniques results from the conceptually simple process of using an equation to express the relationship between a set of variables. These techniques are said to be resistant when the result is not greatly altered in the case a small fraction of the data is altered: techniques are said to be robust of efficiency when their statistical efficiency remains high for more realistic than the utopian cases of normal distributions. These properties are particularly important in the formative stages of model building when the form of the response is not known exactly. Techniques with these properties are proposed and discussed.

First, we present Tiku's (1967, 1970, 1980) univariate MML (Modified Maximum Likelihood) estimation method based on Type-II symmetrically censored normal samples. Next, we describe the extension of this method of estimation as given by Tiku (1988) for the bivariate case and by Tiku and Balakrishnan (1988) for the general multivariate case. Some asymptotic distributional properties of these multivariate MML estimators are also discussed. Then, we develop a robust multivariate linear two-way classification procedure based on the MML (Modified Maximum Likelihood) estimators and demonstrate that it performs overall more efficiently than the classical linear two-way classification procedure, for a fixed value of one of the two errors of misclassification. In the case when both the errors of misclassification are allowed to float, we also show that the robust procedure has a smaller error rate than the classical procedure and a much smaller error rate than non-parametric classification procedures like the nearest neighbour method and the method based on density estimates. For this vivid comparative study examining the performance of these various classification procedures, we use the data obtained from a very elaborative and extensive anthropometric survey conducted by Majumdar (1941) in the United Provinces of India.

Next, the classification procedures where the classification has to be based on the observed value of a pair of variables, one being a dichotomous random variable (univariate or multivariate) and the other being univariate or multivariate continuous variable have been studied. For this study, we consider the existing classification procedures due to Chang and Afifi (1974.) and Balakrishnan and Tiku (1988) and extended the latter method to the case when the data contain a multivariate dichotomous and an associated multivariate continuous variable. 'We illustrate the non-robust characteristic of the Chang and Afifi (1974) procedure through a study of the distribution functions and expected values of errors of misclassification when both errors are allowed to float. After showing that the linear classification procedure could be sensitive to departures from the homogeneity oi variances, we propose quadratic and transformed linear classification procedures for the problem of classification based on dichotomous and continuous variables with the populations differing from each other not only in means but also in variances.

Next, we adopt the modified maximum likelihood approach and derive a robust method of estimation of the parameters in a simple linear regression model. We derive asymptotic variances and covariances of these estimators via the information matrix. Then we compare the performance of this procedure based on MML estimators with many prominent procedures under both normal as well as a wide range of non-normal models for 'the error variable and also under departures from linearity in the simple linear regression model. We present two examples to illustrate the various methods of estimation considered in this study. Finally, we extend these results to the case of multiple linear regression models. Once again, through a comparative study we show that the MML estimators derived in this chapter are quite robust to departures from normality and remain highly efficient under normal and several non-normal models for the error variable.

abstract: Doctor of Philosophy (PhD)


title: An Experimental and Analytical study on the Refilling and Rewetting of Hot Horizontal Tubes

contributor:
Shoukri, M.
Mechanical Engineering

abstract:
This thesis contains the details of an experimental and analytical study on the refilling and rewetting of hot horizontal tubes. The experiments were conducted to refill and rewet two 25.4 mm 1.0., 3 m long zircaloy tubes (1 mm and 2 mm wall thicknesses) under a wide range of initial and boundary conditions. In addition to obtaining the quenching rates and the various parametric effects, the data played an important role in understanding the nature of the quench front propagation and identifying the associated flow patterns. Moreover, the data were used to obtain quench curves at different axial and circumferential locations. These quench curves helped in investigating the parametric effects on the different modes of heat transfer associated with the rewetting process as well as giving valuable insight into the rewetting mechanisms involved in the process.

A rewetting criterion based on vapour film collapse in the film boiling region is proposed. This criterion suggests that surface rewetting is initiated when the vapour film thickness reduces down to a value equal to the sum of the amplitude of the liquid-vapour interface fluctuations and the solid surface roughness. Accordingly, a theoretical model for predicting the dynamic behaviour of the liquid-vapour interface in the film boiling region near the bottom of a horizontal tube was developed. This study showed that the hydraulic disturbances represented by the system pressure fluctuations could induce interface fluctuations capable of rewetting the surface when the equilibrium vapour film thickness was close to the experimentally estimated critical value.

A two-fluid model incorporating the proposed rewetting criterion, as well as derived models for the partition factor and the film boiling heat transfer coefficient, was developed to predict the transients of the refilling and rewetting of hot horizontal tubes. This model is capable of predicting the experimentally observed thermal-hydraulic transients of the refilling "and rewetting processes.

abstract: Doctor of Philosophy (PhD)


title: Schematism and the Possibility of Experience: A Preliminary Study of the Overall Argument of Kant's Critique of Pure Reason

contributor:
Radner, M.
Philosophy

subject: Philosophy Philosophy

abstract: The goal of this study is to reveal to the reader of Kant's Critique of Pure Reason a course he might choose to follow through the text in his journey of interpretation--if, that is, the reader is content to accept as his (temporary) destination the chapter on "schematism." It is here suggested that this chapter can only be understood as belonging to one overall argument which begins as early as the Preface and concludes much further on in the Analytic of Principles (if it can be said to "begin" or "conclude" in the first Critique at all). This study presents the overall argument and offers a "making-sense-of" the schematism as one of its necessary steps.

abstract: Master of Arts (MA)


title: Electrical, Magnetic and Thermal Properties of UNi₂Si₂ and UNi₂Ge₂

contributor:
Datars, W. R.
Physics

subject: Physics Physics

abstract:
The magnetic susceptibility, resistivity, and Hall coefficient of single crystals of UNi₂Si₂ and UNi₂Ge₂ have been investigated. Thermoelectric power and specific heat measurements of UNi₂Si₂ have also been carried out.

The magnetic susceptibility of UNi₂Si₂ and UNi₂Ge₂ follows the Curie-Weiss law in the paramagnetic state at high temperatures and the anisotropy shows that the magnetic moments on the U atoms are constrained to lie preferentially along the c axis.

The resistivity of these two compounds is largely due to magnetic scattering and the phonon contribution only amounts to 8-14% of the total resistivity at room temperature. Along the c axis, the resistivity shows a Kondo type of behaviour at high temperatures. The temperature dependence of the Hall coefficient can be accounted for by a theoretical model invoking a magnetic skew-scattering process. Distinct features and anomalies are observed in both the resistivity and the Hall coefficient at the magnetic transitions of these two compounds.

The thermoelectric power of single crystal UNi₂Si₂ is also anisotropic, with the c-axis component strongly coupled to the magnetic phase transitions. The gamma value obtained from the specific heat measurements of UNi₂Si₂ is 22 mJ mol⁻¹ K⁻² which indicates a small mass enhancement in the system.

abstract: Doctor of Philosophy (PhD)


title: Canadian-American Macroeconomic Interactions: A Sensitivity Analysis Based on Alternative Structural Interpretations of VAR Models

contributor:
Denton, F.T.
Robb, A.L.
Scarth, W.M.
Economics / Economic Policy

subject: Economics Economics

abstract: A number of recent studies have taken a comprehensive view of Canadian-American macroeconomic interactions and have employed vector autoregressive (VAR) modeling techniques to explore the impact of American events on the Canadian economy. The main reason behind the we of the VAR framework is that it requires a minimal set of restrictions, as opposed to traditional econometric practice in which models are generally overidentified. The VAR modeling is highly helpful in exposing more fully the dynamic relationships among model variables. Although the use of VAR modeling may be considered preferable from some points of view, it has been criticized for its atheoretical nature. The critics have argued that any multi-equation model must be provided with set of economically meaningful identifying restriction if purposeful interpretation is required. In the standard VAR framework, identification is achieved simply by imposing the Choleski decomposition on the error covariance matrix. This implies that the underlying economic structure is strictly recursive. Such an assumption may be considered inappropriate since there is no reason that structuraI recursivity should be a prerequisite for the identification of all VAR moles. Much of the evidence from Canadian VAR studies is subject to that limitation. Concern about the possible inappropriateness of the recursivity assumption has led recently to a number of structural VAR studies. These studies remove the neccessity of recursivity and permit the (ezact) identification and estimation of contemporaneous structural relationships based on economic theory. The present study relies on structural VAR modeling and re-examines primarily the contribution of American economic fluctuations to the variability of Canadian economic variables. A variety of representative structures (including neoclassical and Keynesian-type structures) are imposed alternatively on a seven-equation Canadian-American VAR system and their implications for model interpretation are considered. The VAR system includes Canadian and American output, price levels, and money stocks, us well as the exchange rate. In order to capture the effects of the energy shocks of the 1970s the world oil price is also included, as an exogenous variable. The data set is quarterly and seasonally unadjusted. It covers the period 1970:2 to 1987:4 (1970 was the first year in recent times in which the Canadian exchange rate was allowed to float against other currencies.) It turns out that the size and significance of structural estimates are highly sensitive to the ways in which one identifies a model. The sensitivity of the estimates is more prominent in non-recursive, contemporaneous structures. Impulse response functions and variance decompositions are also affected by the choice of identifying priors. Again, the sensitivity of impulse response functions and variance decompositions is more obvious when their calculation is based on alternative non-recursive, contemporaneous structures.

abstract: Doctor of Philosophy (PhD)


title: The Thermoregulatory Response of Pre-. Mid- and Late-Pubertal Boys Exercising in the Heat

contributor:
Bar-Or, Oded
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: Th~ thermoregulatory response to exercise in the heat, especia!ly sweating rate, differs between children and adults. This project investigated the effect of physical maturation on the thermoregulatory response to exercise (50% V02mc.x) in the heat (42°C 20%RH) among circum-pubertal boys, using a mixed cross-sectional, longitudinal design. Subjects were initially divided into three groups, based on Tanner (pubic hair) staging: 16 pre-pubenal (PP, Tanner 1), 15 mid-pubertal (MP, Tanner 2,3,4) and 5 Iatepubertal (LP, Tanner 5). The thermoregulatory response was observed every 6 months for a period of 18 months (4 sessions). Thirty of the 36 boys completed the four sessions. During each session, the exercise task :onsisted of three 20-min bouts of cycling and 10 min rest periods. Measurements included rectal and skin temperatures and hean rate continuously, VO:! at the midpoint of the second bout, forearm blood flow (FBF) upon entry to the climatic chamber and immediately following each exercise bout, sweat collection during each bout, photography of sweat drops after bouts 1 and 2, and whole body sweating rate. Blood samples before and after exercise in the heat were analyzed for hormonal, lactate and electrolyte concentrations. Body temperatures tended to be higher among LP and FBF was higher among PP. However, the rate of heat exchange and heat storage per kg body weight were similar among groups. Sweating rate per body surface area and per gland were higher among LP compared to PP. This was accompanied by lower sweat lactate concentrations during the initial stages of exercise, hi~her lactate excretion rate per gland. ~l')wer activated sw~at gland population density, and higher mean sweat drop area. Aldosterone and prolactin concentrations increased during exercise in the heat in all groups. The increase in prolactin was greater among LP compared to PP. Longitudinal observations tended to support cross-sectional findings. It is concluded that, in boys a) heat exchange and heat storage are similar among preto late-pubescents exercising in dry heat; b) physical maturation is characterized by enhanced sweating rate per body surface area and per gland, and this may be associated with increased sweat gland anaerobic metabolism; c) physical maturation may potentiate the increase in prolactin but not the increase in aldosterone during exercise in the heat.

abstract: Doctor of Philosophy (PhD)


title: Acylation of Membrane Proteins to Enhance Their Water Solubility

contributor:
Gerber, G.E.
Biochemistry

subject: Biochemistry Biochemistry

abstract:
Membrane proteins are an integral part of the structure of membranes providing the functional aspect of the membrane with respect to the transport of water soluble molecules, signal recognition and reaction cataylsis. Primary, secondary and tertiary structure of these types of proteins warrant investigation in order to better understand their individual function. Both DNA sequencing and standard protein sequencing can provide information on the protein's primary sequence. Protein sequencing can identify sites of post-translational peptide bond hydrolysis and translocation and aid in the elucidation of the secondary and tertiary structure. However, the hydrophobic nature of these membrane proteins necessitates the use of detergents or chaotropic agents to achieve the solubilization of the protein and even its peptide fragments under aqueous conditions; in the absence and sometimes even in the presence of these agents, membrane proteins aggregate and precipitate out of solution. Standard protein sequencing techniques are, therefore, hampered by this protein aggregation and insolubility, resulting in incomplete enzyme and chemical cleavage of the protein, general losses of both the protein and the peptide fragments and the overall poor isolation of hydrophobic peptide fragments from one another.

The focus of this research was on the development of a method by which membrane proteins could be chemically derivatized resulting in the formation of a stable product that was soluble in aqueous solutions, in the absence of detergents and chaotropic agents. The methodology consists of the following: 1. Solubilization of the membrane protein in anhydrous pyridine through the utilization of tetrabutylammonium ions which provide a hydrophobic counter ion to the carboxylate groups on the protein. 2. Complete derivatization of the amino add side chain amine and hydroxyl groups with di-trimethylsilylethyl trimesic anhydride, in the presence of the acylation catalyst, 4-pyrrolidinopyridine. 3. Regeneration of the carboxyl groups on the trimesic acid moeity through the selective removal of the trimethylsilylethyl ester groups by tetrabutylammonium fluoride. 4. Isolation of the trimesylated protein by column chromatography or dialysis. Apobacteriorhodopsin was used as the model membrane protein and after this procedure, the trimesylated protein was found to be completely soluble in simple aqueous solutions. This water soluble derivative was shown to chromatograph on Sephadex type columns that were eluted with buffers containing low salt concentrations. It was further shown to be a suitable substrate for the enzyme pyroglutamate aminopeptidase resulting in the quantitative removal of the N-terminal pyroglutamate residue; the native protein is a poor substrate due to its insolubility, under these aqueous conditions.

This method of trimesylation is applicable to all proteins, both membranous and water soluble, generating a trimesylated protein derivative that is completely water soluble. This chemical modification incorporates two carboxyl groups at each site of modification, Lys, Tyr, Ser and Thr side chains; due to the frequency of the hydroxyl amino acid residues even in hydrophobic domains, this modification would also enable peptide fragments to be water soluble.

abstract: Doctor of Philosophy (PhD)


title: Studies on the Chemical Interactions of Nitrofurazone with Nucleic Acids during Ɣ-Irradiation

contributor:
McCalla, D.R.
Biochemistry

subject: Biochemistry Biochemistry

abstract:
Nitrofurazone (NF) alters the radiation chemistry of nucleic acids in hypoxic aqueous solution. (¹⁴C_NF), labelled in the semicarbazone moiety, was found to bind in a stable, covalent manner to DNA, maximum binding occurring under hypoxic conditions. The nuclease plus alkaline phosphatase hydrolysate of the products formed with ¹⁴C- NF and DNA, t-RNA, poly C, and poly U were analysed on a cation exchange column (AG 50WX4) and on an anion exchange column (Sephadex DEAE A25). The mobilities of the adducts on these columns suggested that they are neutral and acidic compounds. Analysis of the nucleoside digest of (¹⁴C- NF )-poiy U, adducts on DEAE anion exchange paper (with and without borate) indicated that these products lack an intact ribose moiety. Analysis of the nucleositle and nucleotide digests of (¹⁴C-NF)-poly U adducts by paper chromatography indicated nucleotide-like products(according to its chromatographic behaviour), and acidic products which appeared to be different from bases, nucleosides or nucleotides. Similar analysis of uracil, uridine, and 5'UMP after exposure to Ɣ-rays in the presence of ¹⁴C- NF, suggested nucleotide-like products with the NF molecule bound to the uracil base.

Experiments with (³H-Me)thymidine-DNA and (³H-Me) thymidine showed the existance of thymine derivatives or break-down products which did not contain radioactivity from the ¹⁴C-NF. Paper chromatograpy of (2-¹⁴C)uracil radiolysis products formed with and without NF showed NF to enhance the yield of a compound tentatively identified as uracil glycol. It is concluded that hydrolysates of the products formed when ¹⁴C-NF reacts with irradiated polynucleotides consist of a large number of compounds which contain ¹⁴C and are therefore likely to be adducts. These can readily be separated from the normal nucleosides which are also present but not from radiolysis products. Thus the analytical problem of isolating pure adduct remains a formidable one.

The ability of NF to increase single-strand break (SSB) production Ɣ-irradiated λDNA was demonstrated and compared to NF binding to λDNA. Values of 0.64-1.08 were found for the ratio of SSB / NF molecule bound.

abstract: Doctor of Philosophy (PhD)


title: Hydraulic Transport of Sand and Lime Slurries in a Vertical Pipeline

contributor:
Latto, Brian
Mechanical Engineering

abstract:
This thesis is primarily concerned with the energy required to hydraulically transport sand and lime slurries in a 5.1 cm.-diameter vertical pipeline for both steady and pulsating flows.

In the steady flow experiments, three different grades of sand of average weighted diameter d = 0.66, 1.20 and 1.84 mm. were investigated. The lime flurry used had an average particle diameter of 1.8 x 10⁻³ mm. The delivered volumetric concentration C₅, the average mixture flow rate Q, and the pressure difference ΔP across the test section were measured within the Reynolds number range of 4 x 10⁴ to 2 x 10⁵.

In the pulsating flow experiments, only one grade of sand of average weighted diameter d = 1.20 mm. was investigated at frequencies of 0.22 and 0.44 cycles per second.

Two methods of predicting pressure gradient for slurry flow were attempted. The first was adapted from Newitt et. al. (1961). By comparing the measured pressure gradient i for various suspensions to those for water flowing under similar conditions iw, an excess dimensionless pressure parameter Φ was obtained. It was possible to correlate the steady flow data using Φ and another dimensionless parameter Ψ related to mixture velocity Vm, diameter ratio D/d and specific gravity of solid S. In the second method the excess pressure gradient (i-iw) is equated to the excess hydraulic head CT(S-1). The results are presented in graphical form and each method is appraised in the discussion.

The energy dissipated per unit height of the test section and mass flow rate was determined for steady and pulsating flow of suspensions. The energy ratio JP/Js at the two frequencies was obtained for low concentration slurries (Cs < 8.0%). It was found that no energy savings were recorded for pulsatile flow under these conditions.

abstract: Master of Engineering (ME)