title: Genetic Variation, Clonal Selection and Balance Polymorphism in Natural Populations of Cyclic Parthenogenetic Rose Aphids (Macrosiphum rosae)

contributor:
Singh, R.S.
Biology

subject: Biology Biology

abstract: This study was undertaken to assess the role of natural selection in the maintenance of genetic variation in natural population of Rose Aphids (Macrosiphum rosae). The selection of rose aphids as organism of choice was based on three features common to all aphids. (1) Their habitat with respect to food (host-plants) is well defined, (2) Their migration potential is large enough that geographical differentiation of allele frequencies are not expected, and (3) Aphids are cyclic parthenogenetic which allows to investigate the role of seasonal change and variation in breeding system on the amount and pattern of genetic variation. A total of nine geographic (Detroit, London, Hamilton, Niagara Falls, Rochester, Syracuse and New York City) and eleven local populations (Hamilton, Ontario) were studied for one morphologoical and fourteen allozyme loci. On an average about thirty percent of loci were polymorphic and an individual was heterozygous for about 4.3% of its genome. All geographical populations expect Detroit and New York had roughly similar allele frequencies. The latter two populations differed somewhat from the rest and these changes are thought to be due to temporal rather than geographical factors. The local variations at eleven sites in Hamilton was remarkably similar to the macrogeographic pattern of variation. Six local populations in Hamilton were studied for temporal variation using four polymorphic loci. All loci showed large genotypic fluctuations over time but the variation at only one locus (Esterase-4) was cyolic in nature. However, the occurrence of intermediate allele frequencies and the temporal changes at all four polymorphic loci strongly suggest that these polymorphism are maintained by balancing selection. The balancing selection in this case is thought to be of the type where genotypes have different fitness during the sexual and asexual generations. Since during the asexual generations, selection acts in the whole genome (clonal selection) any directional change is allele frequencies, whether due to natural selection or hitch hike, must be balance presumably by changes during the sexual generation. In this view the cyclic parthenogenetic breeding system appears to be directly involved in shaping the structure of genetic variation in rose aphids.

abstract: Master of Science (MS)


title: Use of Calcia Stabilized Zirconia and β-/β"-Alumina Solid Electrolytes in Galvanic Cells

contributor:
Kay, D.A.R.
Metallurgy

subject: Metallurgy Metallurgy

abstract:
Thermodynamic measurements were made using the following ionic materials as solid electrolytes in galvanic cells: calcia stabilized zirconia, Naβ and α-alumina, Caβ"-alumina, Kβ- and α-alumina, Laβ- and α-alumina, and Caβ and α-alumina. With the exception of the widely employed calcia stabilized zirconia, the ionic materials utilized in this work have only recently been developed as solid electrolytes. In order to characterize these β-/β"-aluminas for high temperature galvanic cell applications, their chemical stabilities were determined.

The following sections give a description of the various galvanic cells used in the present study, and a summary of the thermodynamic information obtained from each cell.

Calcia Stabilized Zirconia (and Naβ- and α-alumina) Solid Electrolytes in Galvanic Cells for Equlibrium Studies in M-S-O Systems

(M = Ca, Mg, La, K and Na)

The following electrochemical cells were used for thermodynamic equilibrium studies in metal-sulphur-oxygen systems:

Cell I

Pt⎮Cu(s), Cu₂S(s), CaS(s), CaO(s)⎮CSZ⎮Air⎮Pt

Cell II

Pt⎮CaS(s), CaSO₄(s)⎮CSZ⎮Air⎮Pt

Cell III

Pt⎮Cu(s), Cu₂S(s), CaSO₄(s), CaO(s)⎮CSZ⎮Air⎮Pt

Cell IV

Pt⎮Ag(s), Ag₂S(s), MgS(s), MgO(s)⎮CSZ⎮Air⎮Pt

Cell V

Pt⎮Ag(s), Ag₂S(s), MgS(s), MgO(s)⎮Naβ-and α-alumina⎮Ni(s), NiO(s)⎮Pt

Cell VI

Pt⎮Cu(s), Cu₂S(s), La₂O₂S(s), La₂O₃(s)⎮CSZ⎮Air⎮Pt

Cell VII

Pt⎮Ag(s), Ag₂S(s), La₂S₃(s), La₂O₂S(s)⎮CSZ⎮Air⎮Pt

Cell VIII

Pt⎮Ag(s), Ag₂S(s), La₂S₃(s), La₂O₂S(s)⎮Naβ-and α-alumina⎮Ni(s), NiO(s)⎮Pt

Cell IX

Pt⎮K₂S(s), K₂SO₄(s)⎮CSZ⎮Air⎮Pt

Cell X

Pt⎮Na₂S(s), Na₂SO₄(s)⎮CSZ⎮Air⎮Pt

The results from Cells I, III and VI were each combined with the values of ΔGfº for Cu₂S in order to calculate the ΔGº of the following reactions:

CaO + 1/2S₂→CaS + 1/2O₂ Cell I

CaO + 3/2O₂ + 1/2S₂→CaSO₄ Cell III

La₂O₃ + 1/2S₂→La₂O₂S + 1/2O₂ Cell VI

Cells II, IX and X were used to determine the standard free energies of oxidation of CaS, K₂S and Na₂S to their corresponding sulphates.

The results from cells IV and VII were each combined with the values of ΔGfº for Ag₂S to determine the ΔGº of the following reactions:

MgO + 1/2S₂→MgS + 1/2O₂ Cell IV

La₂O₂S + S₂→La₂S₃+ O₂ Cell VII

Cells V and VII were used to confirm that the oxygen pressures developed in the anodes of cells IV and VII were within the electrolytic domain of the CSZ solid electrolyte.

Thermodynamic Stabilities of β-/β"-Aluminas

CSZ solid electrolytes were also used to study the chemical stabilities of Caβ"-alumina, Laβ-alumina, Kβ-alumina, and Naβ-alumina. The following cells were employed in this investigation:

Cell XI

Pt⎮Ag(s), Ag₂S(s), CaSO₄(s)/(CaO)β-(s)⎮CSZ⎮Air⎮Pt

(CaO)β-(s) refers to Caβ-alumina in coexistence with MgO-Al₂O₃(s) and α-Al₂O₃(s).

The results from cell Xl were employed for determining the CaO activities in α-AI₂O₃(s)/MgO-AI₂O₃(s)/Caβ"-alumina coexistence.

Cell XII

Pt⎮Ag(s), Ag₂S(s), La₂O₂SO₄(s), (La₂O₃)β/α(s)⎮CSZ⎮Air⎮Pt

(La₂O₃)β/α refers to Laβ-alumina in coexistence with α-Al₂O₃

Cell XIII

Pt⎮Ag(s), Ag₂S(s), La₂O₂SO₄(s), (La₂O₃)β/ʟᴀ(s)⎮CSZ⎮Air⎮Pt

(La₂O₃)β/ʟᴀ refers to Laβ-alumina in coexistence with La₂O₃-Al₂O₃(s).

Cells XII and XIII were used to obtain the values of La₂O₃ activities in α- Al₂O₃/Laβ-Al₂O₃ and La₂O₃-Al₂O₃/Laβ-Al₂O₃ coexistences.

Cell XIV

Pt⎮Ag(s), Ag₂S(s), K₂S(s), (K₂O)β/α(s)⎮CSZ⎮Air⎮Pt

(K₂O)β/α refers to the Kβ-alumina in coexistence with α-Al₂O₃.

Cell XV

Pt⎮Ag(s), Ag₂S(s), Na₂S(s), (Na₂O)β/α(s)⎮CSZ⎮Air⎮Pt

(Na₂O)β/α refers to Naβ-alumina in coexistence with α-Al₂O₃.

The result from these two cells were utilized in order to calculate the respective alkali oxide activities in α-Al₂O₃/β-Al₂O₃ coexistences.

The thermodynamic stability of Caβ-alumina (CaO-6AI₂O₃) was determined by measuring the CaO activities in α-Al₂O₃/β-Al₂O₃ and CaO-2Al₂O₃/β-Al₂O₃ coexistences. These measurements were undertaken by using Caβ"-alumina as solid electrolyte in the following two calcium concentration cells:

Cell XVI

Pt⎮Air⎮CaO(s),Pt(s)⎮Caβ"-alumina⎮Pt(s),CaO-6Al₂O₃(s),α-Al₂O₃(s)⎮Air⎮Pt

Cell XVII

Pt⎮Air⎮CaO(s),Pt(s)⎮Caβ"-alumina⎮Pt(s),CaO-6Al₂O₃(s),CaO-2Al₂O₃(s)⎮Air⎮Pt

Thermodynamics of CaO-AI₂O₃ System Using Caβ"-Alumina Solid Electrolyte

Caβ"-alumina solid electrolytes were utilized to measure the CaO activities in the CaO-Al₂O₃ system in the following cells (in addition to cells XVI and XVII):

Cell XVIII

Pt⎮Air⎮CaO(s),Pt(s)⎮Caβ"-alumina⎮Pt(s),CaO-Al₂O₃(s),CaO-2Al₂O₃(s)⎮Air⎮Pt

Cell XIX

Pt⎮Air⎮CaO(s),Pt(s)⎮Caβ"-alumina⎮Pt(s),3CaO-Al₂O₃(s),CaO-Al₂O₃(s)⎮Air⎮Pt

Cell XX

Pt⎮Air⎮CaO(s),Pt(s)⎮Caβ"-alumina⎮Pt(s),CaO(s),3CaO-Al₂O₃(s)⎮Air⎮Pt

Two-Phase β- and α-Alumina Solid Electrolytes in Oxygen Concentration Cells

The reversibility of two phase β- and α-alumina solid electrolytes to oxygen potentials were tested using the following cells:

Cell XXI

Pt⎮Fe(s), FeO(s)⎮Naβ- and α-alumina⎮Ni(s), NiO(s)⎮Pt

Cell XXII

Pt⎮Fe(s), FeO(s)⎮Kβ- and α-alumina⎮Ni(s), NiO(s)⎮Pt

Cell XXIII

Pt⎮Fe(s), FeO(s)⎮Laβ- and α-alumina⎮Ni(s), NiO(s)⎮Pt

Cell XXIV

Pt⎮Fe(s), FeO(s)⎮Caβ- and α-alumina⎮Ni(s), NiO(s)⎮Pt

Applications

(i) The data obtained from cells I to X were used to construct the metal- sulphur-oxygen phase stability diagrams at high temperature for the elements Ca, Mg, La, K and Na.

(ii) The phase stability diagrams for Ca-S-O, La-S-O, K-S-O and Na-S-O systems were further extended by including the data for CaO-Al₂O₃ systems (cells XI, XVI to XX),, La₂O₃-Al₂O₃ system (cells XII and XIII), Kβ-alumina (cell XIV) and Naβ-alumina (cell XV) respectively.

(iii) The thermodynamic information from the phase stability diagrams for Ca-S-O (extended), Mg-S-O and La-S-O (extended) were combined with available data in the literature to construct deoxidation- desulfurization diagrams for liquid iron at 1643K and liquid steel at 1873K.

(iv) The results for the chemical stabilities of β/β"-aluminas (cells XI to XVII) were extrapolated to different conditions of temperatures and oxygen partial pressures. These results were used to determine the feasibility of their utilization as solid electrolytes in galvanic cells for industrial applications in iron and steelmaking.

abstract: Doctor of Philosophy (PhD)


title: Studies on NS the Phosphoprotein of Vesicular Stomatitis Virus

contributor:
Prevec, L. A.
Biology

subject: Biology Biology

abstract:
The vesicular stomatitis virus phosphoprotein, NS, was the subject of this investigation. Multiple forms of NS protein were identified in Piry infected cells. These multiple species were demonstrated to be related by comparative peptide mapping under conditions of complete or partial digestion. Furthermore, kinetic studies revealed that one of the NS forms (NSᵢ) could be converted into a mature NS form (NSᵥ) by a covalent post-translational modification. The nature of this modification was investigated using inhibitors of both phosphorylation and acetylation.

NS protein isolated from cells infected with the Indiana serotype was structurally characterized by a variety of techniques including enzymatic digestion, chemical cleavage and partial acid hydrolysis. The observations presented here indicate that NS exists under denaturing conditions as a monomer and is post-translationally modified by multisite phosphorylation. NS isolated from infected cells appears to be phosphorylated toward the amino terminus of the polypeptide primarily in one large tryptic peptide.

Monospecific antisera were raised against SDS-polyacrylamide gel purified Indiana virion proteins. These sera were used to investigate viral protein aggregates in both virions and infected cells. In particular it was demonstrated that a protein kinase activity capable of in vitro phosphorylation of NS protein could be identified in immunoprecipitates of NS protein.

The significance of these findings with respect to other published observations is discussed.

abstract: Doctor of Philosophy (PhD)


title: Nuclear Magnetic Resonance and Mechanistic Studies of Cobalt(III) Complexes

contributor:
Eaton, D.R.
Chemistry

subject: Chemistry Chemistry

abstract:
This thesis describes a number of closely related studies on aspects of the chemistry of Co(III) complexes. Of particular interest are μ-peroxy Co(III) complexes formed by the addition of molecular oxygen to Co(II) containing solutions. These compounds have attracted much attention, partly because they can serve as models for biological oxygen carriers and partly because of their intrinsic chemical interest. A review of some of the pertinent chemistry is contained in Chapter One. A number of interesting questions which remain unanswered, particularly with respect to the unexpectedly rapid rates of ligand exchange reactions and the mechanisms of electron transfer reactions will be addressed in the present thesis.

There are also problems with respect to the characterisation of the complexes in solution particularly in cases where there are a number of isomeric possibilities. ⁵⁹Co NMR has not previously been applied to this area and the thesis reports the initial results of such a study. Some necessary NMR theory is reviewed in Chapter Two. Experimental details for both the chemical and the NMR studies are contained in Chapter Three.

The application of ⁵⁹Co NMR to these di-oxygen complexes resulted in several interesting observations and NMR problems. These topics will be dealt with in Chapters Four, Five, and Six. In Chapter Seven, the application of model for assigning ⁵⁹Co resonances to Co di-oxygen complexes is presented. Finally, in Chapter Eight, some mechanistic studies on ligand exchange and electron transfer reactions are described. Two appendices give computer programmes and some results on the characterisation of Fe compounds produced by oxidation with the Co di-oxygen complexes.

In order to achieve better resolution, high field experiments were performed using superconducting magnet instruments. In the course of these experiments an anomolous field dependence of the linewidths was observed. The interpretation of this effect is the subject of Chapters Four and Five. In the first of these chapters, linewidth measurements on 22 complexes at 3 different fields are reported. Qualitatively, the results are consistent with relaxation due to chemical shielding anisotropy but calculations show that the observed broadening is two to three orders of magnitude greater than expected from this source. Several other possible explanations are considered. It is concluded that the most likely origin of the effect lies in the contribution of antisymmetric components of the chemical shielding tensor, modulated by an abnormally long correlation time which is associated with the lifetimes of hydrogen bonding interactions. Although the existence of antisymmetric components in the shielding tensor has been recognised as theoretically possible for some time, there has been no previous experimental evidence for their importance. This model leads to two predictions - that there will be a large solvent dependence of the field effect and that the very unusual result of T₁ less than T₂ will be found if this relaxation mechanism is dominant. Measurements showing T₁ less than T₂ have not previously been reported. Chapter Five reports the results of experiments designed to check these predictions. The data support the proposed relaxation mechanism. Nine compounds have been examined in a number of different solvents and the results correlated with the Gutmann donor numbers of the solvents. The contributions of quadrupolar relaxation and scalar relaxation of the second kind to the linewidths are assessed. The measurement of very short T₁'s (where T₁ becomes comparable with the instrumental pulse widths) presents some hazards but the predicted values relative to T₂ have been observed. These results suggest a new approach to the study of short lived hydrogen bonded second sphere intermediates of kinetic significance in transition metal complex reactions.

Chapter Six returns to the problem of assigning ⁵⁹Co resonances in complex mixtures. A model is developed for estimating both the chemical shift and the linewidth of an octahedrally coordinated Co(III) complex with any ligand arrangement. This model is tested by application to some 50 known complexes. ⁵⁹Co data on a number of these complexes have not been reported previously. The relative chemical shifts, particularly for complexes with similar ligands, can be calculated with some reliability. The agreement between calculated and observed linewidths is only qualitative but the results are nevertheless useful in making isomeric assignments. In Chapter Seven, this model is applied to Co di-oxygen complexes. Examples involving complex isomeric mixtures are discussed and its use in identifying intermediates produced during the oxygenation of Co(II) solutions containing a variety of ligands is demonstrated.

Finally, in Chapter Eight, some mechanistic studies on Co di-oxygen complexes are described. The mechanism of ligand exchange reactions involving bis(salicylaldehyde)ethylenediimine Co(III) dioxygen complexes has been investigated by stopped-flaw spectrophotometry. The initial step is dissociative ligand exchange. This result is contrasted with literature reports on similar reactions involving complexes containing amine ligands for which the initial step is electron transfer to the Co. The reasons for the high lability of this class of complexes are discussed. The reduction of several amine containing Co di-oxygen complexes by Fe(II) has been followed by stopped-flow spectrophotometry and by ⁵⁹Co NMR. In this case, the mechanistic results agree with literature reports on similar complexes but the interesting observation has been made that the different isomers react at different rates. The structures of the isomers have been assigned using ⁵⁹Co NMR.

Some of the results contained in this thesis are reported in the following publications:

i) Steve C.F. Au-Yeung and Donald R. Eaton, "Characterization of Cobalt-dioxygen complexes by means of High Field ⁵⁹Co NMR" Inorg. Chim. Acta, 76.,L141-144 (l983).

ii) Steve C.F. Au-Yeung and Donald R. Eaton, "Chemical Shift Anisotropy and Second Sphere Hydrogen Bonding in Co(III) Complexes". J. Magn. Reson., 52(3), 351-365 (1983).

iii) Steve C.F. Au-Yeung and Donald R. Eaton. "The Solvent and Field Dependence of ⁵⁹Co NMR linewidths", J. Magn. Reson., 52(3), 366-373 (1983).

iv) Steve C.F. Au-Yeung, Richard J. Buist and Donald R. Eaton. "Spin-Lattice Relaxation of Low Symmetry Co(IIl) Complexes", J. Magn. Reson., in press.

v) Steve C.F. Au-Yeung and Donald R. Eaton. "A Model for Estimating ⁵⁹Co Chemical Shifts and Linewidths and its application to Cobalt di-oxygen complexes", Can. J. Chem., 61, 2431-41 (1983).

vi) Steve C.F. Au-Yeung and Donald R. Eaton. "The Kinetics and Mechanism of the Reaction of μ-Peroxy-bis(Salicylaldehyde)ethylenediimine Co(IlI) with Cyanide and Thiocyanate Ions". Inorg. Chem., in press.

abstract: Doctor of Philosophy (PhD)


title: Mitotic Asymmetry: Differential Behaviour of Sister Nuclei

contributor:
Davidson, D.
Biology

subject: Biology Biology

abstract:
Caffeine, a trimethylxanthine, is a potent inhibitor of cytokinesis in-plant cells; it induces the formation of binucleate cells. The use of binucleate cells is particularly revealing since they make it possible to compare the behaviour of sister nuclei in a binucleate cell with the behaviour of nuclei in sister cells, i.e. to compare the behaviour of sister nuclei in one cytpplasmic environment or in two separate environments. We have used this technique to study the asymmetry of mitosis and the consequences of this asymmetry. With binucleate cells we have shown that a number of differences exhibited by the nuclei of sister cells, i.e. differences in nuclear size, protein content and RNA content, are also exhibited by the sister nuclei of binucleate cells. The fact that these differences occurred in binucleate cells indicates that differences between sister nuclei are inherent and arose as a result of the mitosis from which the nuclei were formed.

The subsequent behaviour of the sister nuclei is also affected by the asymmetrical mitoses. Sister nuclei of binucleate cells showed a differential growth pattern and when supplied with ³H-uridine a differential ability to synthesize RNA. An analysis of nuclei of sister cells revealed an identical pattern of behaviour. This suggests that the asymmetry of division not only produces sister nuclei of different size and macromolecular content but also results in functional differences between the two sister nuclei.

It is proposed that a large degree of heterogeneity in cell size, nuclear size, macromolecular contents of cells and nuclei, and in cell cycle duration is the result of asymmetrical mitoses. The asymmetrical mitoses are responsible for generating, at every mitosis, physical differences between sister cells and these physical differences are functionally related to the differential behaviour of sister nuclei and sister cells.

abstract: Doctor of Philosophy (PhD)


title: The Postnatal Development of Post-Activation Potentiation in the Neocortex and Dentate Gyrus of the Rat

contributor:
Racine, R.J.
Psychology

subject: Psychology Psychology

abstract:
The postnatal development of short-term potentiation (STP) and long-term potentiation (LTP) were examined in the neocortex and dentate gyrus of the rat. It was found that STP and LTP develop during narrowly defined time periods in both systems. This functional synaptic development did not appear to correspond well with known structural development in either system (e.g. synaptogenesis or dendritic spine formation).

Stimulation of callosal fibers produced a biphasic, positive-negative, transcallosal response (TCR) recorded near the surface of the anterior neocortex in all ages tested. The TCR showed a decrease in threshold, latency and halfwidth, and an increase in peak amplitude with age. STP and LTP of the TCR could not be reliably detected until after PN16 and PN18, respectively. The magnitude of STP and LTP was initially small out approached adult levels rapidly after their initial appearance.

Stimulation of perforant path fibers produced a positive excitatory post-synaptic potential (EPSP) with a super-imposed negative population spike recorded in the dentate hilus. The EPSP showed a decrease in threshold, latency and halfwidth, and an increase in peak amplitude with age. STP and LTP (of the EPSP and/or population spike) could not be reliably detected until the second postnatal week, with STP appearing prior to LTP. Again, STP and LTP approached adult levels rapidly after their initial appearance. These results could not be explained by differential effects of anesthesia on immature animals, nor by higher STP/LTP thresholds in immature animals.

The maturation of evoked response morphology (e.g. threshold and latency) did not correspond closely with STP/LTP development in either the hippocampal or neocortical system. Also, the correspondence between STP/LTP development and structural developments such as synaptogenesis, spine formation, or myelinogenesis (as reported in the literature) was not particularly strong in either system.

These results suggest that the postnatal development of STP and LTP, and thus the mechanism of potentiation effects in mature animals, may not depend so much on the maturation of specific structures (e.g. dendritic spines as on the maturation of neurochemical processes (e.g. receptor or protease development). Possible PAP-mechanisms were discussed.

abstract: Doctor of Philosophy (PhD)


title: Molecular fate of adenovirus DNA in eukaryotic cells

contributor:
Graham, Frank L.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
Adenovirus type 5 is able to oncogenically transform cells growing in culture. These transformed cells show different degrees of transformation. The interest of my studies was to establish the presence and characterize the structure of virus DNA in adenovirus 5 transformed cell lines and to look for a possible correlation between the integrated viral sequences and the phenotype of the cells. For this purpose, cell lines transformed by wild type (virions or DNA) and by host range mutants (virions) were analyzed for their viral DNA content and for their transformed phenotype.

More than the left 8% was always present in virion transformed cells. Cells transformed by host range mutants of complementation Group I generally contained a larger fraction of the genome than did their counterparts transformed by wild type virus. In some host range transformed cells, virtually the entire viral DNA molecule was found colinearly integrated.

In the case of the cells transformed by wild type DNA or virions, it was not possible to correlate any particular phenotype with a specific integration pattern. The same pattern was found in the tumorigenic derivatives of a non oncogenic cell line (293) as in the parental line. Studies with cells transformed by Group I host range mutants showed that partial or complete integration of viral DNA into transformed cells was always associated with the production of some viral proteins and with the induction of a partially transformed, non oncogenic phenotype.

An interesting finding was the limited number of inserts in cell lines isolated from uncloned populations within a small number of passages after transformation. This suggested the possibility of a limited number of sites available for transformation or alternatively, that a few cells rapidly overgrew the rest. In an attempt to answer this question and to obtain more information on the integration process, DNA was extracted from semipermissive rat cells at different times shortly after infection. Adenovirus 5 wild type and host range mutants from Groups I and II were used in individual experiments. The extracted DNA was alnalyzed for the presence and state of viral DNA. New forms of intracellular viral DNA, which might be intermediates for integration, were found. A fragment having the size of both ends of the viral DNA joined together, and which hybridizes with both ends when these are used separately as probes, was detected in Southern blots after digestion of rat cell DNA with different restriction enzymes. This structure was detected earlier after infection with host range 1 (Group I), than after infection/with host range 6 (Group II) or with wild type, and was found also in Hela cells and in two rat cell lines after infection with host range J or wild type. Studies followed to determine the nature of this new arranged viral DNA provided evidence for covalent head to tail joining and for the formation of circular Ad5 DNA molecules.

abstract: Doctor of Philosophy (PhD)


title: An Investigation into Anionic Polymerization of Styrene Sulfonic Acid Derivatives and Blood Platelet Reactivity with Two-Phased Polymers Containing Polypropyl-p-styrene Sulfonate

contributor:
Brash, J.L.
Chemical Engineering

subject:
Chemical Engineering
Chemical Engineering

abstract:
This thesis reports on the synthesis, purification and anionic polymerization of several derivatives of styrene sulfonic acid and on the block copolymerization of propyl-p-styrene sulfonate with isoprene and styrene. The domain morphology of polyisoprene:polypropyl-p-styrene sulfonate block copolymers and a one to one blend of the corresponding homopolymers are defined, and blood platelet reactivity with the block copolymers, the respective homopolymers and the blend is investigated.

p-Styrene sulfonamide terminates the anionic initiator (sodium naphthalene) probably by amidolysis. Methyl- and isopropyl-p-styrene sulfonates polymerize but proper purification is extremely difficult. Propyl-p-styrene sulfonate polymerizes, but propagation is halted without termination of the anions after only a relatively low molecular weight polymer is formed. Possible reasons for the formation of these apparently dormant anions is considered in some detail.

The sulfonate-styrene-sulfonate and a broad range of sulfonate-isoprene-sulfonate triblock copolymers were prepared with a range of phase morphology features with dimensions of the order of 100Å. They and the respective homopolymers are all found to induce moderate and indistinguishable in vitro platelet responses as determined by radioactive labeling of platelets and by electron microscopy. In contrast, however, the blend of homopolymers which has phase morphology features with dimensions of the order of magnitude of platelet dimensions is shown to induce nonrandom clustering of adherent platelets. It is possible that morphologies with these dimensions may influence platelet thrombus propagation over the surface.


title: The Phytoplankton Population Dynamics of a Small Reservoir

contributor:
Harris, G.P.
Biology

subject: Biology Biology

abstract:
Time series analysis was used to study the phytoplankton population dynamics of a small reservoir (Guelph Lake, southern Ontario). Three stations were sampled daily for one season (May 8 to August 20, 1981) and weekly at one station for 2 years (fall/1980 to fall/1982). Significant environmental variability was detected at time scales of days to weeks.

Time series analysis of the daily data from 3 stations (maximum separation - 1 km) demonstrated the existence of strong horizontal advection within the basin with a period of 2-3 days and 10-20 day cycles associated with changing weather systems. Rates and directions of horizontal advection varied among different variables. The algal biomass (chlorophyll a) at station 1 lagged that at station 3 by half a day. The time lag between station 1 and station 3 for Aphanizomenon flos-aquae was 7 days, whereas for Ceratium hirundinella station 1 led station 3 by 3 days indicating opposing motion by the species. Longer term (10-20 day) periodicities occurred in between and within station comparisons for soluble reactive phosphorus and total phosphorus. Periodicities in the average daily wind speed and water column stability showed that such lags or leads were due to vertical mixing.

Sedimentation traps were used to examine the settling of diatoms and the recruitment of summer blue-green species. The relationship between physical variables such as water column stability (N², Richardson number) or wind stress and the vertical heterogeneity of chlorophyll a, nutrients and phytoplankton species on a daily basis was examined. High Richardson numbers were better predictors of high vertical heterogeneity than Iow wind speed or N² alone. Higher correlations between physical variables and vertical heterogeneity were obtained in late summer. Relationships between environmental variables and phytoplankton population dynamics were examined on a daily and a weekly basis. Time lags occurred between changes in environmental variables and the abundance of particular phytoplankton as well as the rate of phytoplankton community change.

The results suggest that non-equilibrium conditions prevail in the phytoplankton community of Guelph Lake. Significant environmental variability was detected at time scales of the same magnitude as phytoplankton generation times, time lags occurred between changes in environmental variables and algal abundances and the majority of the increase in the rate of phytoplankton community change occurred in response to allogenic factors. Some of the problems encountered with the use of bivariate time series techniques in phytoplankton are then discussed.

abstract: Doctor of Philosophy (PhD)


title: A Microelectrode Study of Hippocampal Electrical Activity in the Behaving Rat with Special Reference to Hypersynchronous Discharges

contributor:
Smith, G.K.
Psychology

subject: Psychology Psychology

abstract:
The general purpose of this work is to examine the patterns of hippocampal EEG and unit activity during various behavioral states in the rat. Previous research indicates that the hippocampus generates rhythmical slow activity (RSA) during movement and paradoxical sleep. Other states are accompanied by irregular EEG containing "spikes" which are the main subject of this study.

Experiment 1 showed that most neurons in the dorsal hippocampus could be classified into four types according to their firing repertoires and behavioral correlates. Complex spike cells fired core frequently during non-RSA than during RSA. Theta cells, granule cells and fast complex spike cells showed the opposite pattern. Multiunit population bursts (PBs) were observed only during non-RSA. Experiment 2 indicated that in CA1 the PB was accompanied by an EEG spike (SPK) which was positive in oriens and negative in radiatum. SPKs occurred synchronously in the two hippocampi: Experiment 3 revealed that the laminar profile of evoked EPSPs was similar to that of SPKs. Both SPKs in radiatum and PBs in pyramidale were best mimicked by brief trains of high frequency pulses (20-60 msec, 125-250 Hz) applied to afferents. Experiment 4 showed that SPKs and their behavioral correlates were preserved after medial septal and/or entorhinal cortical lesions. Experiment 5 indicated, that SPKs and PBs were reduced by ether, urethane, pentobarbital and diazepam, while they were enhanced by bicuculline. They were not affected by atropine.

These results support the following conclusions. (1) Hippocampal pyramidal cells tend to fire synchronously in bursts during non-RSA states. (2) The CA1 SPK represents a synchronous excitation of middle apical dendrites triggered by synchronous bursts in CA3 via-the Schaffer collateral and commissural fibers. (3) These synchronous events occur when GABA-mediated inhibition is weak. (4) Activation of ascending inputs concurrent with RSA-related behaviors can suppress hippocampal SPKs via medial septal, entorhinal or other pathways.

abstract: Doctor of Philosophy (PhD)


title: The Stereochemistry of Enzymic Reactions at Prochiral Centres

contributor:
Spenser, I.D.
Chemistry

subject: Chemistry Chemistry

abstract:
The steric course of decarboxylation of L-ornithine to yield putrescine, catalysed by L-ornithine decarboxylase (E.C. 4.1.1 17) of E. coli, and of L-arginine to yield agmatine, catalysed by L-arginine decarboxylase (E.C. 4.1.1.19) of E. coli, is investigated by deuterium labelling. Replacement of the carboxyl group by a solvent derived proton occurs with retention of configuration in each case.

In conflict with an earlier report, incubation of cadaverine in deuterium oxide in the presence of L-lysine decarboxylase (E.C. 4.1.1.18) of B. cadaveris did not lead to entry of deuterium into the α-position of cadaverine. Likewise, L-ornithine decarboxylase did not catalyse exchange of the α-hydrogen of putrescine, nor did L-arginine decarboxylase catalyse such an exchange in agmatine.

The stereochemistry of hydrogen abstraction in the conversion of cadaverine into 'Δ'-piperidine, of putrescine into Δ'-pyrroline, and of agmatine into 4-guanidinobutanal, catalysed by hog kidney diamine oxidase (E.C. 1.4.3.6) is investigated. The Si-hydrogen from C-1 of the substrate is removed while the Re-hydrogen from C-1 of the substrate is maintained at the Sp² carbon atom of each of the products.

The diamine oxidase catalysed oxidative deamination of cadaverine takes place without detectable isotope effect, while an intramolecular primary hydrogen-deuterium isotope effect (kHsi./kDsi = 4) is observed in the diamine oxidase catalysed oxidation of putrescine.

abstract: Doctor of Philosophy (PhD)


title: Modelling and Control of Sustained Oscillations in the Continuous Emulsion Polymerization of Vinyl Acetate

contributor:
Hamielec, A. E.
Chemical Engineering

abstract:
The population balance model of Kiparissides (1978) for the continuous emulsion polymerization of vinyl acetate, has been extended to predict molecular weight moments and has been corrected for induction time and particle shrinkage due to density changes. The developed model was successfully able to simulate experimental results from Kiparissides (1978) and Greene et al.(1976) for the continuous emulsion polymerization of vinyl acetate. Application of the model to the batch data of Keung (1974) had reasonable access as well. The model was extended to the continuous emulsion polymerization of styrene which follows different nucleation kinetics and was able to predict the average conversions and particle diameters for the data of Brooks et al.(1978). Little success was achieved in predicting the small experimentally observed oscillations for the styrene system.

To eliminate the sustained property oscillations in the vinyl acetate system Linear-Quadratic stochastic optimal control theory was applied to the model. Due to extreme non-linearities inherent in the system, this approach was shown to be inadequate. Instead, the reaction system was redesigned to include a small continuous seeding reactor with monomer and water bypass. Model predictions indicated that the redesigned system eliminated the oscillations. Experimental testing of the redesigned system verified that a dramatic improvement in stability was possible. The redesigned reactor configuration was also shown to be more flexible in controlling particle sizes and conversion through use of the bypass.

A method for selecting the optimum sensors was developed. It was shown that the measurement combination providing the most information would be conversion (as currently available from an on-line density meter) and some measure of weight average molecular weight.

abstract: Doctor of Philosophy (PhD)


title: Structural Studies of Platinum Complexes

contributor:
Lock, L. C. J.
Chemistry

subject: Chemistry Chemistry

abstract: The molecular and crystal structures of platinum complexes relevant to the cancer research field are investigated. The complexes whose structures have been studied, encompass many aspects of the chemistry of platinum(II): the preparation of starting materials, the solvolysis of the complexes in different solvents and the chemistry of the complexes with DNA bases. The important structural features of the complexes are outlined and, where possible, the molecular structures are related to previous information on the complexes which is available from animal studies, solution work or the interaction of the complexes with the DNA macromolecule.

abstract: Doctor of Philosophy (PhD)


title: Finite Element Analysis of Two-dimensional Polymer Melt Flows

contributor:
Vlachopoulos, J.
Mirza, F. A.
Chemical Engineering

abstract:
A general purpose finite element program has been developed for numerical modelling of flow of polymer melts through processing equipment. Several problems have been solved for two-dimensional creeping flow. These include flow in the gap between calender rolls, driven cavity flows and planar entry and exit flows with free surfaces (extrudate swell) in slit dies. Newtonian, power-law and viscoelastic models have been used under isothermal and nonisothermal conditions. Slip at the boundary walls has also been incorporated. An "upwind" scheme for triangular elements has been used to stabilize the solution when convection is considered in the nonisothermal analysis. The free surfaces are determined through an iterative technique that allows no flow normal to the surface.

The finite element analysis of calendering shows that the power-law model describes adequately the behaviour of the polymer melt and the results are in good agreement with experimental data. The shape and location of the free surface of the melt bank is also determined an compares well with photographs available in the literature. Entry and exit flow calculations in slit dies and the determination of extrudate swell are in good agreement with theoretical and experimental studies for inelastic fluids. Visco-elastic calculations performed using the Criminale-Ericksen-Filbey (CEF) constitutive equation diverged for high elasticity levels (Deborah number above 1.0). A simple constitutive equation based on empirical relations for polymer melts was found to enjoy a wider convergence range for elasticity levels encountered in practical situations (De < 5). It predicts several phenomena of polymer melts such as vortex size and intensity, entrance and exit pressure losses and extrudate swell in agreement with experimental findings. It is proposed that such empirical relations can be used along with the finite element method to predict successfully the flow of polymer melts in various polymer processes.

abstract: Doctor of Philosophy (PhD)


title: Improved Absorbing Boundary Conditions for Time-Domain Methods in Elecromagnetics

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

subject:
Electrical and Computer Engineering
Electrical and Computer Engineering

abstract: This thesis contributes to the development of novel absorbing boundary conditions (ABCs) for two finite-difference time-domain (FDTD) methods in computational electromagnetics; the well-known FDTD method to the solution of Maxwell's equations and the wave equation in the time-domain (WTD) method. The conventional approach to create a perfectly matched layer (PML) ABC for the FDTD solution to Maxell's equations is reviewed, as well several other state-of-the-art techniques to define a PML medium. The novel WETD technique is described for applications in numerical algorithms both for optical waveguides and structures, and in the microwave and millimetre-wave structure analysis. The new algorithm requires a reliabe efficient ABC, which can handle both open problems (i.e., radiation and scattering) and problems involving port terminations (such as high-frequency circuit problems and optical guiding structures). A new degree of freedom is introduced in the definition of the PML variable profiles and thus improved algorithms for PML ABCs are formulated and developed both for the WETD method and for the FDTD solution to Maxwell's equations. The proposed modified PML profiles handle equally well both port terminations in guide-wave problems and truncations of the computational domain of open problems. The performance of the proposed PML absorber is further improved by new types of PML termination walls using single-layer ABCs. For that, a lossy version of Mur's second order ABC and a lossy version of the second order dispersive boundary condition (DBC) have been developed on orthogonal non-uniform grids. It handles inhomogeneous dielectrics intersecting the PML boundaries. Various numerical simulations have been carried out to validate the theoretical models at microwave and optical frequencies, as well as in depth detailed comparison with commonly used PML ABCs is presented. Suggestions for further research are provided.

abstract: Doctor of Philosophy (PhD)


title: Saccharomyces cerevisiae aspartate kinase mechanism and inhibition

contributor:
Wright, Gerard D.
Biochemistry

subject: Biochemistry Biochemistry

abstract: Aspartate kinase (AK) from Saccharomyces cerevisiae (AKsc) catalyzes the first step in the aspartate pathway responsible for biosynthesis of L-threonine, L-isoleucine, and L-methionine in fungi. Little was known about amino acids important for AKsc substrate binding and catalysis. Hypotheses about important amino acids were tested using site directed mutagenesis to substitute these amino acids with others having different properties. Steady state kinetic parameters and pH titrations of the variant enzymes showed AKsc-K18 and H292 to be important for binding and catalysis. Little was known about how the S. cerevisiae aspartate pathway kinases, AKsc and homoserine kinase (HSKsc), catalyze the transfer of the ϒ-phosphate from adenosine triphosphate (ATP) to L-aspartate or L-homoserine, respectively. Two transfer paths are possible as are a range of mechanisms, with two extremes. Both kinases were shown to directly transfer the ϒ-phosphate from ATP to the amino acid. Experimental evidence was consistent with an associative mechanism of phosphoryl transfer but did not rule out a dissociative mechanism. AKSc and HSKsc are good targets for inhibitors because they catalyze phosphoryl transfers between very similar substrates. An attempt was made to rationally design inhibitors to these kinases by linking the substrates with a variable length linker to create bisubstrate compounds. This strategy failed inhibit AKsc and HSKsc, however, one of the bisubstrate compounds was a good inhibitor of AKIII from Escherichia coli. Inhibition of any of the enzymes in the aspartate pathway would lead to reduced production of amino acids. A pathway assay was optimized to allow screening of chemical libraries in the hope of identifying inhibitors to the first four pathway enzymes. A high throughput screen of 1,000 compounds identified two compounds capable of inhibiting the assay, one of which was the best inhibitor identified for AKsc.

abstract: Doctor of Philosophy (PhD)


title: The Effects of a Skill-Based Pay System on Organizational Commitment and Role Orientation

contributor:
Agarwal, Naresh C.
Business Administration

subject: Business Business

abstract: Faced with continuing competitive pressures over the last few decades, organizations have been driven to seek more innovative approaches to management. In the compensation management area, skill-based pay (SBP) is one such innovative approach that is being increasingly applied. However, there is a paucity of research on this approach to pay and the consequences of applying it relative to the more traditional job-based approach to pay. The current study examines how SBP affects employees' perceptions of their employment relationship with particular focus on organizational commitment and role orientation. Using data from a large sample of employees from a steel manufacturing company, it finds that selected perceived SBP plan characteristics are significant predictors of employees' beliefs about the SBP plan fairness and effectiveness, organizational commitment, and role orientation. The study discusses the various theoretical and practical implications that result from these findings.

abstract: Doctor of Philosophy (PhD)


title: Posthumous Praise: Biographical Influence in Canadian Literature

contributor:
King, James
English

subject:
English Language and Literature
English Language and Literature

abstract: This dissertation explores the phenomenon whereby a number of deceased Canadian women writers have had their lives utilized in subsequent works of fiction, drama, poetry, film, and biography. The dissertation gives this phenomenon a name-biographical influence-and argues that it represents a challenge to traditional literary canonicity in the Canadian context. Whereas literary canonicity has traditionally been the domain ofliterature professors, the phenomenon of biographical influence may be read as a writer-enacted substitution for traditional canonicity. This writer-enacted canon is comprised of literary heroines who have been elevated to their status not, as is traditional, because of the value oftheir work. Rather, entry to this new canon is reserved for writers whose lives often come close to eclipsing the value ascribed to their work. This is an ironic canonicity that valorizes the writer's life, while claiming to valorize the writer's work. Recent critiques by Lucasta Miller of the Bronte myth, Jacqueline Rose and Janet Malcolm of Sylvia Plath's posthumous status, and by Brenda Silver of Virginia Woolfs iconicity are a manifestation of the cross-pollination of Cultural Studies discourse with English Studies that this dissertation seeks to emulate. While Harold Bloom's "anxiety of influence" comes closest to providing the language with which to name the phenomenon this thesis describes, his theory does not account for three important differences in the Canadian context. First, instead of re-writing precursors' works, in Canadian literature, writers re-write their precursors' lives. Second, instead of this re-writing coming from a defensive position, in Canadian literature the intention is to aid the precursor's reputation, in many cases to solidify it. Finally, Bloom's theory cannot explain why it is that in Canadian literature, most "precursors" are women and not men. In the foreshortened female literary careers of Gwendolyn MacEwen and Pat Lowther, as well as in Susanna Moodie's life, the dissertation argues that some contemporary Canadian writers have found, among other things, a metaphor for expressing the large odds against literary success in this country. To explain the metaphor, the dissertation elaborates an argument based on Nancy Armstrong's reading of the rise of the novel that sees literary desire as the basis of biographical influence in Canada. It then uses close readings of works in which Susanna Moodie, Gwendolyn MacEwen, and Pat Lowther appear as characters, as well as Carol Shields' Swann and Margaret Atwood's The Blind Assasin-novels where biographical influence is fictionalized-as evidence for the phenomenon of biographical influence.

abstract: Doctor of Philosophy (PhD)


title: Financial Filtering and Model Calibration

contributor:
Feng, Shui
Mathematics

subject: Mathematics Mathematics

abstract: The main topic of the thesis is the hidden Markov chain filtering for diffusions with jumps. The finite-dimensional filters are obtained for various statistics including the state of the hidden Markov chain. EM (Expectation Maximum) algorithm is then applied to the estimation of parameters of the hidden Markov chain. Based on some financial phenomena, we propose a model, called regime switching mean reverting with jump model, for an asset price or interest rate. We apply the filtering methodology to this model and obtain the estimator for the mean reverting level. Monte Carlo simulation is performed in estimating the parameters of hidden Markov chain. The numerical methods for stochastic differential equations which are used in diffusion with jump model are discussed. Some fundamental results on stochastic calculus and some basic methods on generating random variables and sample paths are provided.

abstract: Doctor of Philosophy (PhD)


title: Studies of Magnetism in Rhenium and Manganese Based Perovskite Oxides

contributor:
Greedan, John E.
Physics

subject: Physics Physics

abstract: The bulk of this thesis consists of studies of geometric frustration in S = 1/2 FCC perovskites based upon the chemical formula A₂BReO₆. The magnetism of these materials is expected to exhibit geometric frustration, a situation in which the ideal spin arrangements cannot be achieved for antiferromagnetic interactions between adjacent spins. It is proposed that subtle quantum effects are driving these systems to unique ground states in the absence of chemical disorder. Both compounds Sr₂CaReO6 and Sr₂MgReO₆ exhibit spin glass behaviour at low temperatures (TG ~14 K and TG -50 K respectively), in which the magnetic moments freeze out in random orientations instead of an ordered array. This work shows that these materials possess several unconventional properties, which suggest that interesting spin dynamics may be present. Other perovskite and perovskite-related materials studied in this thesis include the magnetoresistive CaMn03_o and the "pillared" material La₅Re₃MnO₁₆. Neutron diffraction studies have shown that both CaMnO2.94 and CaMn02.89 order at TN - 125 K, but possess unique yet related magnetic structures. CaMnO2.94 orders into a simple Gtype magnetic structure, as observed in the compound CaMnO₃. The slightly more doped sample CaMn02.89, on the other hand, orders into a magnetic structure related to the Gtype, and involves a Mn³/Mn⁴⁺ charge ordering over every four lattice spacings. The new material La₅Re₃MnO₁₆ consists of layers of comer shared ReO₆ and MnO₆ octahedra that are separated by layers of Re₂O₁₀ dimer units. Metal-metal bonding involving Re atoms have been postulated for these dimers which separate the Re/Mn layers by approximately 10 Å. The magnetic behaviour exhibited by this new class of materials is rich and complex. Despite the large distances separating the perovskite layers, the Re and Mn magnetic moments order into a ferrimagnetic Q = (0, 0, 1/2) structure below a relatively high TN of 161 K. There may be an additional spin rearrangement at lower temperatures as evidenced by weak magnetic Bragg peaks below ~ 50 K.

abstract: Doctor of Philosophy (PhD)


title: The Relationship Between Postsecondary Education and Labour Market Outcomes: Comparing Graduates Over a Four-Cohort Period

contributor:
Fox, John
Sociology

subject: Sociology Sociology

abstract: Drawing on data from the 1982, 1986, 1990, and 1995 National Graduates Surveys, this dissertation win build on previous research comparing graduates of different types of postsecondary programs on various outcome measures including earnings, employment, objective and subjective over-education, and the mismatch between education and work. Particular emphasis is placed on making field of study comparisons among graduates of different levels of post-secondary schooling (i.e. trades, college, university undergraduates, professional, master's, and Ph.D.), and identifying changes over time. The central theoretical issue addressed in this dissertation involves comparing the viability of human capital theory and the credentialist perspective with respect to the relationship between post-secondary education and skins. Statistical analyses are made using ordinary least squares, ordered logistic, and multinomial logistic regression models.

abstract: Doctor of Philosophy (PhD)


title: Ancient Maya Ceramic Economy in the Belize River Valley Region: Petrographic Analyses

contributor:
Finsten, L.
Anthropology

subject: Anthropology Anthropology

abstract: Ancient Maya ceramic economy during the Late to Terminal Classic Period (800-900 A.D.) is the focus of this dissertation. I employed ceramic thin section petrology, raw materials sourcing, and contextual archaeological analyses. Samples from a variety of excavated sites in the Belize River Valley region were included in this study: Pacbitun, Cahal Pech, Baking Pot, El Pilar, Xunantunich, Blackman Eddy, Floral Park, and Ontario Village. Standardized petrofabric descriptions enabled the definition of distribution spheres for the ceramics. My study used intersite comparison of distributional patterning to explore issues such as the scale, integration and disposition of the ceramic economy. A number of economic models were used heuristically to examine the possible meaning of the distributional patterning observed. I propose that ancient Maya economic systems were much more complex than have been suggested to date. I suggest a hierarchy of sites existed. This hierarchy was a framework that supported a diversity of distributive networks or spheres signifying varying degrees of economic involvement on the part of a number of sites or communities.

abstract: Doctor of Philosophy (PhD)


title: Three Essays in Empirical Labour Economics

contributor:
Kuhn, Peter J.
Burbidge, J.B.
Magee, Lonnie
Economics

subject: Economics Economics

abstract: This thesis is a collection of three essays that use what have arguably become the three most common empirical strategies found in the labour economics literature. The first essay uses descriptive analyses to document and explain a long-term secular increase in on-the-job search (OJS) in the U.S. and Canada between the mid-l 970s and mid-l 990s. Based on observed concomitant trends in job-to-job transition rates and returns to wage changing, the OJS increase appears most consistent with a long-term reduction in the costs of searching while employed. Moving beyond descriptive analyses, the second essay takes an instrumental variables approach to estimating the effectiveness of internet job search in reducing unemployment durations. Although raw means indicate shorter unemployment spells among internet searchers, the evidence from a more complete model that controls for observable characteristics suggests no effect of using the internet on unemployment durations. Finally, the third essay employs a differences-tn-differences strategy to infer the employment and hours of work effects of Sunday shopping deregulation. The results suggest that deregulation led to a long-run increase in labour demand that was disproportionately satisfied through an increase in the employment level. In conclusion the thesis offers some insights into the relative advantages and disadvantages of these three identification strategies.

abstract: Doctor of Philosophy (PhD)


title: A Theoretical Model for the Cross-Flow Induced Fluid-Elastic Instability in Heat Exchanger Tube Bundles

contributor:
Weaver, D.S.
Mechanical Engineering

subject:
Mechanical Engineering
Mechanical Engineering

abstract: A simple theoretical model has been developed from first princples for the cross-flow induced fluid-elastic instability in heat exchanger tube bundles. A series of experiments were conducted to verify the basic assumption that only a single tube need be modelled in a flow channel which preserves the basic geometry of the array. The mechanism of dynamic instability is found to be one of flow redistribution due to transverse tube motion and a phase lag resulting from fluid inertia. Static instabilities in both streamwise and transverse directions are also predicted, but at higher reduced flow velocities than the transverse dynamic instability. Quite good agreement is found with available experimental data, particularly for parallel triangular and square arrays, without the need for empirical fluid force coefficients. The model includes the effects of tube array pattern and pitch.

abstract: Doctor of Philosophy (PhD)


title: Characterization and Mapping of a DNA Degradation Function (Cyt) in Adenovirus

contributor:
Mak, S.
Biology

subject: Biology Biology

abstract:
The cyt mutants of the highly oncogenic adenovirus type 12 (Ad12) produce low yields of virus and are generally weakly tumorigenic. In this study, four cyt mutants examined were-shown to induce extensive degradation of DNA in infected cells. Complementation tests using two cyt mutants, host range and host range-deletion mutants of Ad5, and wild type Ad12 and Ad5 in various cell types, suggested that two viral functions are involved in the control of DNA degradation. One of these functions, a DNase-inhibitory function, mapped by genetic complementation in early region E1b of the Ad5 genome. A transcriptional study of early region E1 of the Ad12 genome identified mRNA species complementary to the left 10.5 percent of the genome by the method of RNA-blot hybridization. Ad12 appeared to possess a region E1b physically corresponding to that of Ad5, suggesting that the DNas-inhibitory function also maps in this region in Ad12. Results implicated the association of this function with an E1b-19,000 dalton polypeptide of both serotypes. The second viral function appeared to influence positively the induction of DNA degradation. This DNase-effecter function appeared to be an early viral function. Results of time course-superinfection experiments in which cyt mutant-infected cells were superinfected with wild type strains of Ad12 and Ad5 and analyzed for the properties of DNA degradation and virus yields, support the hypothesis that the degradation of DNA is determined by the relative abundance of the DNase-inhibitory factor and the DNase-effecter, and that the two factors might functionally interact with each other.

A supplementary study on the interference with the DNA replication of Ad12-strain 1131 by an Ad12-strain Huie variant, Ad12 Huie (MB), suggested that the interference capacity lies in a nucleotide sequence repeat structure at the right terminus of the Ad12-Huie (MB) genome.

abstract: Doctor of Philosophy (PhD)


title: A Macroeconometric Model for Sri Lanka

contributor:
Butterfield, D.W.
Denton, F.T.
Welland, D.
Economics / Economic Policy

subject: Economics Economics

abstract: In this study a disaggregated macroeconometric model is developed and estimated for the Sri Lankan economy. Since there have been few quantitative analyses of the economy, our study supplies valuable information to other researchers and to decision-makers in the country. Based on the literature available, this is the first macroeconometric model for the Sri Lankan economy estimated with time series data. The main purpose of the model is to examine how the various subsectoral outputs and prices are determined and subsequently how these sectoral values determine the aggregate real output and general price levels; the GNP deflator and the cost of living index. Sri Lanka is a developing country and its major economic problems are mainly related to the supply side of its economy. Hence, our model takes both supply and demand factors into consideration but gives more emphasis to the supply side of the economy. In the present model outputs and prices are determined by domestic market forces, government economic activities, and international market forces. The economy is disaggregated into major sectors and each sector is in turn divided into a number of subsectors. The choice of subsectoral disaggregation is determined by the importance of subsectors in the economy. Since the government plays an important role in the economy, government expenditure, income and budget financing are taken into consideration. Subsequently, determination of the money supply, general price levels, exports, imports, the balance of payments and aggregate real output are considered. Both the government budget constraint and the balance of payments constraint are taken into account in our model. The complete model is made up of 35 behavioural equations, 7 market clearing conditions, 47 identities, 89 endogenous variables, 40 exogenous policy varIables and 42 other exogenous variables. To estimate the model, annual time series data for Sri Lanka are used for the period 1950 to 1980. In the first stage subsectoral models are estimated separately. In the second stage the entire model is reestimated based on selected principal components. The predictive ability of the model is evaluated based on historical simulation results. Subsequently a set of simulation experiments designed to evaluate the effects of the changes in various exogenous variables on the endogenous variables are carried out, and a conditional forecast for the period 1981 to 1990 is calculated using the model. The simulation results suggest that aggregate output can be increased by transferring government expenditure from consumer subsidies to producer subsidies and/or by shifting government expenditure amongst production subsectors. Foreign aid is not inflationary and its effects on real output and prices differ according to the use to which it is put.

abstract: Doctor of Philosophy (PhD)


title: Spectroscopic Studies of Tin(IV) and Mixed Oxidation State Tin(II)Tin(IV) Compounds

contributor:
Birchall, T.
Chemistry

subject: Chemistry Chemistry

abstract:
Proton n.m.r. data are presented for the solvolysis of hexamethylditin and tetramethylt in with fluorosulfuric acid. The tetramethylditin dication [(CH₃)₄Sn₂²⁺] is proposed as an intermediate in the suggested reaction sequence for the solvolysis of hexamethylditin with fluorosulfuric acid.

The reaction between hexamethylditin and a series of carboxylic acids has been investigated. Compounds of empirical formula (CH₃)₂Sn(O₂CR) were prepared and formulated as the tetramethylditin carboxylates, (CH₃)₄Sn₂(O₂CR)₂. Infrared, Raman, ¹H and ¹³C n.m.r. and ¹¹⁹Sn Mössbauer data are presented for this series of compounds. The compounds have been shown to have a tetramethylditin moiety in which the carboxylate ligand bridges both tin atoms. The X-ray crystal structure of three of these compounds [R = CH₂Cl, CCl₃ and CF₃] are presented and the spectroscopic data evaluated in light of the crystallographic data. The X-ray crystal structure of {[(CH₃)₂Sn(O₂CCF₃)]O)₂ is also presented. The solvolysis of hexaphenylditin by a series of carboxylic acids was investigated. Seven novel compounds of empirical formula Sn(O₂CR)₃ were synthesized. Infrared, Raman and ¹¹⁹Sn Mössbauer spectra are reported for the series of Sn(O₂CR)₃ compounds which are best formulated as [Sn(II)Sn(IV)O(O₂CR)₄O(OCR)₂]₂. ¹¹⁹Sn Mössbauer data for Sn(O₂CR)₄ are also presented. The X-ray crystal structure of [Sn(II)Sn(IV)O(O₂CCF₃)₄]₂C₆H₆ has been determined and its relationship to other mixed oxidation state tin carboxylates examined.

The solvolysis of hexaphenylditin by inorganic acids has been investigated. ¹¹⁹Sn Mössbauer spectra are presented for the products and vibrational (infrared and/or Raman) data for the isolated solids. Compounds of empirical formula SnF₃, Sn(SO₃CF₃)₃ and Sn(IV)O·SO₄Sn(II)(SO₃F)₂ are formulated as the polymers [Sn(II)Sn(IV)F₆]ᵪ, [Sn(II)Sn(IV)(SO₃CF₃)₆]ᵪ and [Sn(IV)O∙SO₄Sn(II)(SO₃F)₂]ᵪ. The Sn(SO₃R)₃ compounds where R = CH₃, C₂H₅ and OH were not isolated free of excess acid. ¹¹⁹Sn Mössbauer spectroscopy also showed that these products contain tin(II) and tin(IV) and the formulation of [Sn(II)Sn(IV)(SO₃R)₆]ᵪ is suggested.

The interaction of SnF₂ with Sn(SO₃CF₃)₃ produced Sn₃F₂(SO₃CF₃)₆. ¹¹⁹Sn Mössbauer data together with infrared and Raman data have been interpreted in terms of a compound of formulation [(Sn(II)SO₃CF₃)₂Sn(IV)F₂(SO₃CF₃)₄]ᵪ.

abstract: Doctor of Philosophy (PhD)


title: Discrete Simulation of Flexible Manufacturing System

contributor:
ElMaraghy, H.A.
Mechanical Engineering

abstract:
A Flexible Manufacturing System is an integration of machine tools, material handling devices and computers into a system designed to improve productivity in the mid-volume production.

Although a number of such systems have been designed, relatively little is know about the managing and optimal operating conditions of such systems. Even less is known about how future systems should be designed for optimal efficiency. The main objective here is to develop a user-oriented general purpose simulator which can be used as an experimental tool to gain insight into the problems posed by such complex systems.

The developed FMSSIM simulator uses the discrete event simulation approach, incorporating the philosophy of the GASP simulation package in event monitoring. It is capable of simulating different configurations and topology including bidirectional tracks. It can check blockage of route due to interference of carts. It can also simulate random failures and repairs of the various components in the system. It provides the user with a wide range of priority rules to select from. It also allows the user to define his own priority rules.

The main features of this simulator are: (1) Ease of use: FMSSIM is a user-oriented package where simulation is transparent to the user. Only a set of input data needs to be supplied. The program will perform the simulation and produce a report on various vital system performance statistics.

(2) Graphical Output: The program produces a graphical output on a visual display terminal showing the movement of parts through the system.

(3) Data Input: The program has a systematically organised data structure where information can be easily modified and retrieved.

A series of experiments were conducted using this simulator to test its versatility and study the behaviour of a hypothetical Flexible Manufacturing System when various design parameters are changed. The response of the system to changes in transporter speed, in- and out-shuttles capacity and number of pallets was studied. Two different types of material handling systems viz. the cart and the conveyor were compared. The effects of introducing an additional machine and changing the system topology were also examined. The general trends of results obtained from the case study are in agreement with the findings reported in other published literature.

The ability to simulate a wide range of systems with varied design parameters has made the FMSSIM simulator a very useful design aid which enables the system designer to analyse various parameters and arrive at a more efficient system.

abstract: Master of Engineering (ME)


title: Stochastic Modeling and Estimated with Application to Orbit Prediction

contributor:
Sinha, N.K.
Electrical Engineering

subject:
Electrical and Electronics
Electrical and Electronics

abstract: The objective of satellite orbit determination is to accurately estimate a set of orbital elements which describes the orbit of the satellite, using observations of the satellite. The extended Kalman filter has been extensively used for the estimation of the orbital states. The purpose of this work is to find alternative approaches that would reduce the amount of on-line computation required. A nonlinear estimator combining the invariant imbedding concept with stochastic approximation is proposed for this application. A switching criterion utilizing the properties of tile innovations sequence is applied to the combined estimator. Pugacev's estimation theory is also highlighted and the Kalman filter equations are derived as a special case of the general theory. Alternative approaches for forecasting the observables of the satellite via stochastic modeling techniques are proposed. One-step ahead forecasts are obtained using both univariate and multivariate time-series methods. Also, a recursive algorithm for estimating the degree of differencing most suitable for a given time-series is proposed. The results of simulation indicate the efficiency and reliability of the proposed schemes.

abstract: Doctor of Philosophy (PhD)


title: Fast Neutron Method for Local Void Fraction Distribution Measurement in Two-Phase Flow

contributor:
Banerjee, S.
Meneley, D.A.
Nuclear Engineering

subject:
Nuclear Engineering
Nuclear Engineering

abstract:
A new method is presented for measuring local void-fraction and its distribution in gas-liquid two-phase flow. The method is based on reconstructing the physical distribution of steam and water (phase distribution) from the energy spectrum of fast neutrons scattered in the test section. The unique relationship between neutron energy and angle of single scatterings in the liquid phase is utilized to reconstruct the phase distribution.

Monte Carlo simulations of scattering in the test sections have been used in developing the method. The validity of the Monte Carlo methodology for this purpose is discussed within the logic of the MORSE computer code employed in this work. The usage of the code is verified by simulating actual experiments during the course of the work.

The neutron scattering problem is formulated into non-linear mappings of the phase distribution to the measured neutron spectrum via matrices. The phase distribution is reconstructed by solving the inverse problem posed by the mappings. The non-linearity is overcome by applying a series of successive-approximations to the mappings. The mathematical foundations of the inverse problem are discussed and its implementation in the form of a numerical algorithm is shown.

The energy spectra of the scattered neutrons are measured for a few test sections, and the results are shown to compare favourably with those obtained from Monte Carlo simulations. The techniques used in the measurements are also discussed.

The conclusion of this study is that the proposed new method can be applied successfully for measuring phase distributions of gas-liquid flows. The method in contrast to other radiation methods, requires only a single exposure of the test section to radiation. The inverse problem of reconstructing the phase distribution is solvable and the required neutron energy spectrum can be measured using available techniques. The only restriction is that the test section diameter has to be of order of one mean-free-path of the source neutrons in the scattering medium (about 100 mm in water for 14 MeV neutrons). This is necessary to reduce the contributions from neutron rescattering that complicate the reconstruction problem.

abstract: Doctor of Philosophy (PhD)


title: Development and Application of the Delta-DM Method for Computing Shortwave Radiative Fluxes in a Vertically Inhomogeneous Atmosphere

contributor:
Davies, J.A.
Geography

subject: Geography Geography

abstract:
This study describes the development and application of the Delta-DM method for computing shortwave radiative fluxes planetary albedo and heating rates in vertically inhomogeneous atmospheres. Delta-DM was designed to minimize computer time requirements, furnish accurate flux estimates and permit a wide range of shortwave radiative transfer problems to be studied. Phase function approximation is variable and there is no restriction on either the number of layers into which the atmosphere may be divided or on composition of individual layers.

The Delta-DM algorithm is based on the discrete ordinate method for solving the radiative transfer equation and includes several major refinements: (i) replacement of Gauss-Legendre quadrature for the source function with shifted-Legendre quadrature; (ii) replacement of quasi-analytical solutions for eigenanalyses with fast, efficient subroutines based on the QR algorithm; and (iii) inclusion of Wiscombe's δ-M method for phase function truncation. Comparison of results with the doubling method indicate low order approximations provide two to three significant digit accuracy for a large combination of atmospheric optical parameters.

A block-tridiagonal algorithm is applied to solve the sparse system of equations defining monochromatic fluxes in a multi-layer atmosphere. This approach is found to be both efficient and accurate and makes Delta-DM particularly well suited for problems where fluxes or derived quantities are desired for the same atmosphere but different boundary conditions.

Absorption of radiation by water vapour and ozone is based on distribution of absorption coefficients determined from line parameter data (Chou and Arking, 1981) for water vapour and low resolution transmittance model LOWTRAN4 (McClatchey et aI., 1974) for ozone. Comparison of modelled heating rates with line-by-line calculations reveals maximum errors in Delta-DM heating rates of ~ 0.02°C day¹. Comparison of atmospheric albedo and absorptivity, computed from Delta-DM, with benchmark radiative transfer calculations of Braslau and Dave [1972] demonstrates excellent agreement: maximum differences are less than three percent.

Delta-DM was applied to compute vertical profiles of downward, upward, and net shortwave fluxes for a variety of atmospheric conditions over the tropical North Atlantic Ocean. Cloud droplet and aerosol (Saharan dust) size distributions were not measured on these occasions so that these parameters had to be prescribed. Comparison of estimated fluxes with measured fluxes from aircraft traverses revealed root mean square errors of estimated fluxes of less than 10 Wmˉ² for cloudless, dust-free atmosphere; ~ 20 Wmˉ² for cloudless but hazy conditions; and ~ 75-100 Wmˉ² for combined cloud-haze conditions. Measured and estimated cloud absorption were in virtual agreement. The larger root mean square errors for the cloud cases also reflect the difficulties of accurately measuring cloud thickness and cloud liquid water contents. Comparison with a similar study (Slingo et aI., 1982) using measured cloud droplet distributions suggests that errors in estimating cloud thickness, liquid water contents, and employing model clouds to determine cloud optical parameters, amount to approximately 60 Wmˉ²

abstract: Doctor of Philosophy (PhD)


title: Prime Ideals and Localization in Noetherian Ore Extensions

contributor:
Müller, B.J.
Mathematics

subject: Mathematics Mathematics

abstract:
This thesis studies the prime ideals in a certain class of non-commutative polynomial rings known as Ore extensions. For a right Noetherian Ore extension R[x;σ], the prime ideals are of three types: one type corresponds to the prime ideals of the coefficient ring R, another type corresponds to certain semiprime ideals of R, and the third type is in bijective correspondence with the irreducible polynomials in certain ordinary polynomial rings.

The second part of the thesis studies the question of the localizability of prime ideals in Ore extensions of commutative Noetherian rings. It is shown that these rings satisfy Jategaonkar's second layer condition and that the corresponding skew Laurent polynomial ring is Krull symmetric. Using these properties and the classification of prime ideals, a complete description of the obstructions to localizability - the links between prime ideals - is obtained.

abstract: Doctor of Philosophy (PhD)


title: Far-infrared Studies of bis-tetramethyltetraselenafulvalene Salts [(TMTSF)₂X, X=(ClO₄, SbF₆ & ASF₆)]

contributor:
Timusk, T.
Physics

subject: Physics Physics

abstract:
Detailed far-infrared reflectivity measurements were done for three organic compounds, bis-tetramethyltetraselenafulvalene (TMTSF) perchlorate (ClO₄), hexafluoroantimonate (SbF₆) and hexafluoroarsenate (ASF₆). One of these compounds (TMTSF)₂ClO₄, was also studied by measuring the transmission through a grid of crystals. The grid technique was used to enhance the absorption of a material brought on by the application of a magnetic field. The (TMTSF)₂ClO₄ compound shows an increased absorption below ≃ 3.8 meV with a field of 0.2 Tesla.

The reflectance data were Kramers-Kronig transformed to get the real part of the frequency dependent conductivity σ₁(ω), and the real part of the dielectric constant ε₁(ω). In the metallic state, σ₁(ω) can be described by two relaxation times. The first is an extremely long lifetime Tc (> 10ˉ¹¹ s) needed to account for the high dc conductivity (10⁴-10⁵ (Ω.cm)ˉ¹). We shall call this the 'zero frequency mode'. The high frequency 'tail' of the zero frequency mode can be seen in (TMTSF)₂SbF₆ and ASF₆. An effective mass M* of 250-650 m* was obtained for the zero frequency mode. The second is the frequency dependent scattering time tp due to phonons (Holstein process). In the Holstein process, the conductivity profile shows an initial increase in σ₁(ω) as a function of frequency before levelling off at the limiting value of Tp.

None of the three compounds in the semiconducting (spin density waves (SDW)) state show the well developed SDW gap that is predicted theoretically. For (TMTSF)₂ClO₄, a gap of 20 cmˉ¹ was observed in the 'quenched state' while for (TMTSF)₂SbF₆ it is ≃ 180 cmˉ¹. In the latter compound, 'phase phonons' accompanied the SDW transition. This is the first observation of phase phonons in the SDW state. The third compound studied, (TMTSF)₂AsF₆, did not show any identifiable SDW gap.

abstract: Doctor of Philosophy (PhD)


title: Dynamics of Optically-Pumped Pulsed Mid-Infrared NH₃ Lasers

contributor:
Garside, B.K.
Reid,  AssociateJ.
Physics

subject: Physics Physics

abstract:
An extensive theoretical and experimental study of the dynamics of optically-pumped pulsed NH₃ lasers is presented. The results completely characterize the small-signal gain of NH₃ lasers operating on rotational-vibrational transitions in the mid-infrared wavelength range from 10 to 21 μm. Two gain mechanisms are identified from the experiments: single-photon inversion gain and two-photon Raman gain.

Raman gain is described by a density-matrix model as a coherent interaction of two radiation fields with three molecular levels. Raman emission is offset in frequency from the line center of the emitting transition, and is the dominant process both at large pump offsets and in pure NH₃. The Raman process and the ac Stark effect, which shifts the optimum gain frequency, are always present in NH₃ lasers and affect all transitions which have one level in common with the pumped transition.

Significant population transfer produces inversion gain which is the dominant gain process in mixtures of NH₃ with a buffer gas. A rate-equation model is developed based on the assumption of rapid rotational thermalization in all vibrational levels within, but not between, ortho-NH₃ (K=3n) and para-NH₃ (K=3n±1). The model accounts for the observed distributions and magnitudes of inversion gain for a wide range of pumping conditions. The thermalization concept makes it possible to characterize a gain distribution by the ratio of vibrational populations.

Another important consequence of rotational thermalization is the prediction and demonstration of a new line-tunable NH₃ laser. A two-step pumping process produces lasing from 16 to 21 μm on many ortho-NH₃ 2v₂ transitions.

A final interesting prediction of the rate-equation model is that a 10-atm NH₃ laser is feasible. At this pressure, there is a potential for tuning the laser emission across 36% of the wavelength range from 10.5 to 13.8 μm, and for producing pulses as short as 10 ps.

abstract: Doctor of Philosophy (PhD)


title: Near-Surface Soil Heat and Water Fluxes in Different Permafrost Terrains, Churchill, Manitoba

contributor:
Rouse, Wayne R.
Geography

subject: Geography Geography

abstract: Soil temperatures and active layer depths were recorded near Churchill, Manitoba to determine the near-surface thermal regime for three different permafrost terrains. Soil moisture and net radiation were measured also. The interaction between the heat and water balance of the active layer was investigated to observe the short term effects of water movement on active layer development. Results show that the soil heat component of the surface energy budget composed 18% of the net radiation in the grassland, 14% in the peat and 13% in the tundra. In all terrains at least 93% of the soil heat is consumed in latent heat of fusion. Evaluation of the water budget indicates a large subsurface water loss from the upland tundra and a moderate gain in the grass lowlands during the summer period. Active layer development is shown to respond to both the conductive heat flux and the thermal exports and imports associated with the subsurface water flux.

abstract: Master of Science (MS)


title: An Innovations Approach to Discrete-Time Detection Theory with Application To Radar

contributor:
Haykin, S.
Electrical Engineering

abstract:
A very rapidly convergent solution (in the form of a likelihood ratio test) for the problem of detecting a discrete-time stochastic process in additive white Gaussian noise is derived.

This likelihood ratio test is then applied to the problem of moving-target (aircraft) detection by airport surveillance radar systems. Using real radar data, the receiver operating characteristics are obtained for two different adaptive implementations of this likelihood ratio test, and also for the three versions of the Moving Target Detection algorithms presently in use in modern radar systems.

The better of the two adaptive implementations employs Kalman prediction error tapped delay-line filters and attains a minimum of 3 dB average performance improvement relative to the Moving Target Detection algorithms.

abstract: Doctor of Philosophy (PhD)


title: A Dissociative Analysis of Sudomotor Response Patterns

contributor:
Roberts, L.E.
Psychology

subject: Psychology Psychology

abstract:
This thesis is concerned with the nature of the response patterns that accompany the learned control of autonomic responding. Specifically, the thesis examined the role of respiratory adjustments in learned increases in electrodermal responding. Experiment 1 measured the concomitants of learned electrodermal control in unconstrained subjects, and employed correlational analyses to examine relationships between autonomic and concomitant activities. The results indicated that even though several activities were altered during training, only respiratory changes showed evidence of being functionally coupled to electrodermal changes. Functional coupling refers to that class of relations in which performance of the concomitant directly contributes to the autonomic change, presumably because of the neural organization of the response systems involved.

Experiment 2 directly addressed the question of whether respiratory alterations were necessary for the production of electrodermal increases. Subjects were trained to alter both electrodermal activity and respiration (integration) and to alter electrodermal activity while maintaining a constant pattern of respiration (dissociation). This procedure allowed for an assessment of two questions. First, could significant electrodermal increases be produced in the absence of respiratory change? Second, would the magnitude of electrodermal change on dissociation trials be comparable to that seen on integration trials? An affirmative answer to the first question would establish that respiratory changes are not required for the production of learned increases in electrodermal activity. However, a negative answer to either question would suggest that respiratory changes were functionally coupled to electrodermal performance.

It is possible that dissociation performance may be poor, not because respiratory maneuvers contribute to electrodermal performance through functional coupling, but because dissociation is a more difficult task than integration. The information-processing demands associated with learning to change two responses in different directions may be greater than the information-processing demands associated with changing two responses in the same direction. To assess this possibility, a second group of subjects was employed substituting gross body movement for respiration. Gross body movement showed no evidence of functional coupling to electrodermal change in the first experiment, and thus it was felt that this group would serve to estimate the extent of any impairment of dissociation performance due to task difficulty.

The results of Experiment 2 demonstrated that respiratory alterations were not necessary for electrodermal increases to occur. Four of five subjects showed significant electrodermal increases on both integration and dissociation trials by the end of 18 training sessions. Furthermore, three of these four subjects produced changes of comparable magnitude on the two trial types. However, subjects did not appear to produce their electrodermal changes in isolation from other ongoing behaviors. In particular, manipulations of the volar surfaces (fingers and palms) may have contributed to electrodermal responding.

The thesis concludes with a discussion of the role of functional coupling, and the learning process itself, in determining the nature of the response patterns accompanying learned autonomic control.

abstract: Doctor of Philosophy (PhD)


title: Far-Infrared Studies of Excitons in Germanium and Silicon

subject: Physics Physics

abstract:
This thesis examines three aspects of exciton physics by using far-infrared (FIR) spectroscopy. First, the energy level structure of free excitons was investigated in germanium under the application of a uniaxial, compressive stress along the [lll] direction. At high stress, the exciton absorption spectra display a nearly hydrogenic-like structure with strong, isolated absorption lines. A theoretical model was developed to predict the positions and strengths of these absorption lines. Excellent agreement was obtained between experiment and theory. This is in contrast to the situation at zero stress where the exciton spectrum is not understood very well.

Then, the first measurement of the FIR absorption spectrum of a bound exciton is reported. This spectrum provides information on the odd parity excited states of the bound exciton which cannot be observed using conventional near-infrared spectroscopy. The bound exciton absorption spectrum was found to be in excellent agreement with those of acceptors in silicon, giving the best confirmation of the model of the energy level structure of an isoelectronic bound exciton.

Finally, the thermodynamic equilibrium between free excitons and carriers is investigated in germanium. Their absolute concentrations were obtained from their FIR absorptions. Measurements of the exciton and carrier concentrations allowed a direct determination of the equilibrium constant for any given temperature and carrier generation rate. The experimental equilibrium constant was found to be in excellent agreement with the classical equilibrium constant of an ideal gas.

abstract: Doctor of Philosophy (PhD)


title: Sedimentation in a Fjord-Head Delta, Bella Coola, British Columbia

contributor:
McCann, S.B.
Drake, J.J.
Middleton, G.V.
Geography

subject: Geography Geography

abstract:
The Bella Coola delta is a laterally confined, steep-fronted, coarse-grained fjord-head delta in North Bentinck Arm in tile Coast Mountains of British Columbia. River mouth morphodynamics are directly related to the large tidal range (3.9 m mean range, 5.9 m large range). The tide changes the location and nature of the zone of marine-riverine interaction, producing a high tide and a low tide outlet. Frictional forces dominate at high tide as the effluent disperses over the delta plain through four morphodynamic zones and a radial bar. During low tide, frictional, inertial and buoyant forces and an internal hydraulic jump control the formation of five morphodynamic zones and a lunate-middle ground bar.

The subaqueous delta consists of a sandy delta front with slopes of 2.2 to 15° and a silt-clay prodelta sloping at 0.5 to 2.2°. Debris flow or turbidity current chutes and their depositional zones, shallow and deep-seated rotational slides, growth faults and folds are the primary morphologic components. Sediment instability and deformation are mainly a result of gravitational forces, earthquake loading, retrogression, oversteepening of distributary mouth bar fronts, and excess pore pressures produced by gas generation, depositional loading and rapid tidal drawdown.

The sediment package of the Bella Coola delta and North Bentinck Arm consists of two seismic sequences units, a lower probably Pleistocene sequence and an upper delta - related sequence. A glacial moraine facies and a glaciomarine facies characterizes the lower unit. The upper sequence delta plain sediments are well stratified sands and gravels deposited by distributary channels, with some rippled sands and peat. Delta front sediments probably consist of sand and mud laminae deposited from suspension, debris flow sands and gravels, graded sand and slit associated with turbidity currents and undisturbed bedding in slide blocks. Massive silts and clays deposited from suspension and graded sand and silt turbidities compose the prodelta. Rotational slides, growth faults with displaced beds and roll-over anticlines, and folds related to creep processes have deformed prodelta sediments.

abstract: Doctor of Philosophy (PhD)


title: Preparation and Structures of Some S-N and S-Se-N Heterocycles

contributor:
Gillespie, R.J.
Chemistry

subject: Chemistry Chemistry

abstract:
The interest in the metal-like superconducting polymer poly(sulfur nitride) has inspired numerous studies of other sulfur-nitrogen compounds. This thesis deals with the preparation and structures of cyclic S-N cations and S-N heterocyles containing selenium.

The reactions of S₄N₄ with Lewis acids AlCl₃ and HSO₃F have given two new S₄N₄²⁺ salts, (S₄N₄)(AlCl₄)₂ and (S₄N₄)(SO₃F)₂. A study of their X-ray structures as well as those of (S₄N₄)(Sb₃F₁₄)(SbF₆) and (S₄N₄)(SbCl₆)₂ have shown that the S₄N₄²⁺ cation has a planar form and a nonplanar form. A normal coordinate analysis has been carried out on the planar S₄N₄²⁺ ion based on the vibrational data obtained for (S₄¹⁵/¹⁴N₄)(AlCl₄)₂ and (S₄N₄)(SO₃F)₂. The reaction of S₄N₄ with H6O₃F also produced the (S₆N₄)(SO₃F)₂ and (S₆N₄)(S₂O₂F)₂ salts, whose crystal structures are reported. The last compound contains the previously unreported S₂O₂Fˉ anion.

S₄N₄ has been shown to react with the homopolyatomic cations S₈²⁺, Te₆⁴⁺ and Se₈²⁺/Se₄²⁺ to give S₆N₄²⁺, S₃N₂⁺ and the previously unreported Se₄S₂N₄²⁺ cation, respectively. The crystal structures of (S₃N₂)(AsF₆), (S₆N₄)(AsF₆)₂, (Se₄S₂N₄)(AsF₆)₂ and (Se₄S₂N₄)(SbF₆)₂ are reported along with their infrared spectra. The S₆N₄²⁺ and Se₄S₂N₄²⁺ cations are dimeric in that they contain two five-membered S₃N₂⁺ or Se₂SN₂⁺ rings linked by "long" S--S or Se--Se bonds.

Uv-visible absorption and ESR spectra obtained on all the AsF₆- salts suggested that the dimers dissociate to monomers in solution. Magnetic susceptibility data for (S₃N₂)(AsF₆) have confirmed that this salt contains a radical with one unpaired electron. The magnetic susceptibility and differential scanning calorimetric measurements obtained for (S₆N₄)(AsF₆)₂ and (Se₄S₂N₄)(AsF₆)₂ have shown that both compounds undergo a reversible first-order phase transition coincident with magnetic behaviour that is consistent with a dimer-monomer interconversion.

A study of the reactions of S₄N₄ and S₃N₃Cl₃ with Se₂Cl₂ and SeCl₄ resulted in the preparation and the X-ray crystallographic study of the compounds (S₅N₅)(SeCl₅) and SeS₂N₂Cl₂. The (S₅N₅)(SeCl₅) salt is the first well-characterized example of a compound containing the pentachloroselenate (IV) anion. The compound SeS₂N₂Cl₂ contains neutral SeS₂N₂Cl₂ molecules as well as the ions SeS₂N₂Cl⁺ and Clˉ in the same crystal. The ⁷⁷Se- and ¹⁵N-NMR spectra of SeS₂¹⁵/¹⁴N₂Cl₂ in H₂SO₄ is reported and vibrational data obtained for SeS₂¹⁵/¹⁴N₂Cl₂ and S₃¹⁵/¹⁴N₂Cl₂ are discussed.

abstract: Doctor of Philosophy (PhD)


title: Instrumentation for Rainfall Sampling

contributor:
Kitai, R.
Electrical Engineering

abstract: An instrumentation package for sensing rainfall amount and intensity with fine time and space resolution is described. The package comprises a drop counter precipitation sensor, a microcomputer-based data acquisition system, and an intelligent data decoder. The accuracy of the precipitation sensor and the parameters that affect it are discussed. The reliability is reviewed and typical rainfall data are included. A comparison is made between the performance and accuracy of the new precipitation sensor and conventional tipping bucket raingauges. The merits and demerits of the new system are discussed.

abstract: Doctor of Philosophy (PhD)


title: The Social Origins of Early Modern Mechanism

contributor:
H.Levitt, Cyril
Sociology

subject: Sociology Sociology

abstract:
It is argued that the fundamental concepts of early modern, mechanistic science are in part socially constituted. Mechanism is here understood as a conception of nature wherein natural objects are abstractly reduced and homogenised such that they come to be viewed as comprised of one primary material. Sensually intuitable events are then seen as explicable in terms of the mathematical relation between qualitatively similar particles.

This abstraction is gained by analogy to a society which is becoming similarly abstract. When the pivotal relation in society becomes that between owners of exchangable commodities, a similar abstraction occurs in the commodities. Qualitatively different goods come to be seen as commensurate in terms of "value". The mathematics and record-keeping which develop to keep track of "value", understood as an expression of a social relation, become the basis for a similarly abstract science of nature.

Of the major contributors to the early modern mechanistic view of nature, the work of many is seen to be in some way commercially inspired. Although no direct links are found for Galileo, Vieta, Descartes or Bradwardine, for Tartaglia, Bombelli, Oresme, Pacioli and Stevin, a rather strong connection exists. Concepts in early modern mathematics and mechanics thereby bear reference to a more abstract and homogeneous object.

abstract: Doctor of Philosophy (PhD)


title: Pulsating Flow of Non-Newtonian Fluids in Pipes

contributor:
Round, G.F.
Mechanical Engineering

abstract:
The first part of this thesis contains a theoretical formulation and solution for unsteady flows (pulsatile and start-up flows) of non-Newtonian time-independent fluids through rigid pipes. The approach was based on the use of the equation of motion for axisymmetric unsteady flow of fluids in cylindrical coordinates. In the case of pulsating now, the unsteady behaviour of the pressure gradient was considered to be described by a periodic function of time, of sinusoidal form, added to a stationary pressure gradient, while for start-up flow the fluid was assumed to start its transient motion from rest due to instantaneous and sudden imposition of a stationary pressure gradient. The constitutive equation of generalized Bingham fluids was used since it represents the majority of time-independent fluids.

A grid was imposed on the flow field in order to obtain a system of equations in finite difference form. The use of finite difference techniques provided detailed information about the time deformation of the pulsating and start-up velocity profiles as well as valuable information about energy consumption and flowrates under different pulsating flow conditions. The results are presented in the most general form so that they are widely applicable to any case where the assumptions and the boundary conditions are all satisfied. The main conclusion which can be drawn from the theoretical results is that the hydraulic power required to transport a fluid in pulsating flow is never less than that required for the same flowrate under steady flow conditions for all fluids except those which exhibit yield stress, i.e., Bingham fluids.

On the experimental side, an investigation of pulsating flow of solid-liquid mixtures is presented. Solid-liquid mixtures are divided into two types, homogeneous suspensions and pseudohomogeneous/heterogeneous slurries. The terms homogeneous and pseudohomogeneous are used when solids concentration gradient along pipe vertical axis is constant for homogeneous flows and almost constant for pseudohomogeneous flows; while the term heterogeneous represents the cases where appreciable solids gradient along pipe vertical axis exists.

The experiments were carried out for two types of solid-liquid mixtures. The first was a bentonite clay-water suspension with weight concentration ranges from 2.97% to 11.2%, while the second has coal/water slurry with weight concentrations between 5.34%-53.7%.

The main aim of the experimental rig was to create a sinusoidal pressure gradient. The experimental set-up allowed different ranges of different flow parameters to be adopted, these were:

1. Pulsing frequency ranging between 0-1.25 Hz.

2. Pulsing amplitude (axial deformation of rubber bellows) of 34.6, 52.1 and 76.2 mm.

3. Average flow velocity at 1.63, 2.18, and 2.63 m/sec.

The effect of different combinations of these parameters on the ratio of the hydraulic power in pulsating flow to that in steady flow for the same throughput was studied.

abstract: Doctor of Philosophy (PhD)