title: The Typical and Atypical Development of Fine-grained Sensitivity to the Direction of Eye Gaze

contributor:
Maurer, Daphne
Rutherford, M. D.
Psychology

subject:
gaze
development
children
vision
autism
face
Child Psychology
Clinical Psychology
Cognition and Perception
Developmental Psychology
Personality and Social Contexts
Social Psychology
Child Psychology

abstract: Typical adults use gaze cues to make inferences about people's mental and emotional states. I investigated the development of fine-grained sensitivity to the direction of gaze during middle childhood, and how development differs in high-functioning adults with autism spectrum disorder (ASD). In Study 1, sensitivity to deviations of gaze from an object in the environment improved after age 6, becoming adult-like by age 10. This improvement may allow more precise inferences about others' interests and/or intentions. In Study 2, the horizontal range of directions of gaze perceived as direct (the cone of gaze) narrowed considerably after age 6, becoming adult-like by age 8. This narrowing may reduce social costs associated with erroneously perceiving direct gaze. In contrast, the vertical cone of gaze was adult-like at age 6. In Study 3, 6-year-olds' horizontal cone of gaze was narrower when they heard object-directed voice cues (e.g., “I see that.”) than when they heard participant-directed voice cues (e.g., “I see you.”) or no voice, a result suggesting that object-directed voice cues can allow more adult-like judgments of gaze. In Study 4, face inversion increased the width of the cone of gaze in typical adults, but not in those with ASD. However, the cone of gaze was normally modulated by facial expression in the ASD group. This pattern suggests that in adults with ASD, sensitivity to the direction of gaze is not tuned to be finer for upright faces, but that information is nevertheless integrated across expression and gaze. Together, these results suggest that although some aspects of sensitivity to the direction of gaze are adult-like at age 6, immaturities in other aspects of sensitivity will limit children's social judgments until at least age 8. The results also suggest that adults with ASD use atypical visual processing to discriminate the direction of gaze.

abstract: Doctor of Philosophy (PhD)


title: Hunter, Adult Adolescent, and Wounded Warlock: Images of Men in English-Canadian Women's Fiction (1960-93)

contributor:
Coldwell, Joan
English

subject:
literarchy archetypes
masculinity
Arts and Humanities
English Language and Literature
Literature in English, North America
Arts and Humanities

abstract:
Although the fiction written by women in English-Canada since the 1960's has experimented widely with literary form, a remarkably consistent set of - literary archetypes of masculinity emerges from their work. I have named the three particularly vivid and pervasive images of men on which I focus, the Hunter, the Adult Adolescent, and the Wounded Warlock. My project is essentially a sketching out of these beings, a contouring of their recurring literary reality.

Toril Moi rightly criticizes the project of evaluating literary images of women in terms of their true or false relation to 'real life' as one that "resolutely refuses to consider textual production as a highly complex, 'overdetermined' process with many different and conflicting literary and nonliterary determinants" (Moi 45). In looking at the images of men that dominate Canadian women's writing, I do not wish to claim that these images are 'true' or 'false', but simply that they exist in the literature.

My critical approach here is essentially one of description. My descriptions are original in that they are not applications of previously-defined archetypes of personality as in, for example, the work of Carl Jung. No description is, however, free of context, and in describing the images of men that emerge from this fiction, I draw repeatedly upon several feminist and philosophical texts for inspiration and clarification. Susan Griffin's exploration of the 'pornographic mind', Martin Buber's religious ontology of the "I-Thou", JeanPaul Sartre's articulation of the meaning of the Look, and Christopher Lasch's discussion of narcissism, have been particularly useful.

Although my dissertation does not attempt to engage directly the large question of the relation of the artistic image to life, I do suggest indirectly, by drawing upon thinkers whose subject is not primarily literature, but indeed 'the real world', that the images of men I define have some connection with that real world. My conclusion briefly raises, therefore, some ethical as well as aesthetic questions about the implications of their existence.

abstract: Doctor of Philosophy (PhD)


title: Alloying Effects and the g-factor in Antimony measured by the de Haas-van Alphen Effect

contributor:
Datars, W. R.
Physics

subject: Physics Physics

abstract:
The dHvA frequencies, cyclotron masses, and Dingle temperatures of antimony-tellurium alloys with up to 0.11 at.% Te were measured using the low frequency field modulation technique. The hole and electron frequencies decreased and increased respectively, as predicted by the rigid band model. At the highest concentration, the increase is about 25% that of pure Sb and the decrease is about 20%. The cyclotron masses of electrons and holes changed with concentration. This dependence resulted from the nonparabolicity of the Sb bands. Estimates of the Fermi surface volume of the alloys indicated that each Te atom contributes one electron to the alloy. The present results are compared with previous dHvA results on antimony-tin alloys.

Antimony g-factors of holes and electrons were also determined by the dHvA effect using the torque and field modulation methods. Possible g-factors were deduced from the harmonic content in the oscillation waveform following the method described by Randles. A measurement of the g-factors at certain field directions was also obtained from spin-splitting of the oscillations observed at high magnetic fields. The excellent agreement between the results of these methods suggests the validity of the Lifshitz-Kosevich equation for antimony and the absence of non-linear effects. The choice of g-factors for electrons from the several possibilities allowed by the data analysis was determined through a theoretical calculation in the effective mass approximation. These values are consistent with spin resonance and infinite field phase measurements. The choice of hole g-factors was made from a comparison with spin resonance data. The g-factors at the binary, bisectrix and trigonal directions are ~15, 16.8, 3.5 and 4.5, 18.0, 14.5 for the principal branches of electrons and holes, respectively.

abstract: Doctor of Philosophy (PhD)


title: The Characterization of Medea, Dido, Ariadne and Deianira in Ovid's "Heroides" and "Metamorphoses"

contributor:
McKay, A.G.
Roman Studies

subject: Ovid

subject: characterization of women

subject: female psyche

subject: poetry

subject: crisis

subject: anxieties

subject: conflicts

subject: Ancient History, Greek and Roman through Late Antiquity

subject: Arts and Humanities

subject: Classics

abstract:
Ovid's characterization of women has long been recognized as revealing an understanding of the female psyche. This is shown not only in his love poetry, but also in his depiction of women in the Heroides and Metamorphoses. The Heroides in particular offered considerable scope for the portrayal of women in a state of crisis and for an exploration of their anxieties and conflicts. The verse letters reveal Ovid's interest in portraying women at an early point in his literary career, an interest which he continued throughout his writing career and which again finds expression in the Metarmorphoses.

While Howard Jacobson's study (Princeton, 1974) treats all the single letters, Florence Verducci (Princeton, 1985) has restricted her work to five of the fifteen single letters. Little attempt has been made to trace Ovid's depiction of women from the Heroides into his later works. This work investigates the characterization of Medea, Dido, Ariadne and Deianira as they are initially portrayed in the Heroides and as they are later depicted in the Metamorphoses.

Each chapter details early accounts of the heroines, followed by an exploration of the characterization in the Heroides and Metamorphoses. It is shown that, while Ovid's knowledge and use of his predecessors is apparent, his ability to adapt the mythological details concerning his heroines creates an entirely new depiction; his portrayal varies from the Heroides to the Metamorphoses due to the demands of the respective genres and to the emphasis which he wishes to place. Despite the familiarity of his figures, Ovid has created divergent, yet coherent, interpretations of pyschological and emotional crises.

abstract: Doctor of Philosophy (PhD)


title: Reading Nehemiah: A Structural Analysis of Nehemiah's Covenant Renewal Account and Its Place within the Book of Nehemiah

contributor:
Boda, Mark J.
Evans, Paul S.

subject:
literary appraoches
Ezra-Nehemiah
structural analysis
Arts and Humanities
Religion
Arts and Humanities

abstract: Literary approaches to Ezra-Nehemiah studies are becoming more common. However, there is still a lack in the literary study of Ezra-Nehemiah of a structural analysis of Nehemiah's covenant renewal account that respects its particular fit within Nehemiah's story. The aim of this thesis is to explain how the covenant renewal account (commonly held to be Neh 8-10) is integral to the book ofNehemiah (Neh 1-13). Since narrative structural analysis is the study of the semantic structures that preside over a text's creation, this methodology is well suited to discerning whether or not the content found in the covenant renewal account fits within the broader story (and text) of Nehemiah. Accordingly, my structural analysis of the covenant renewal account reveals a deep, underlying structure that shows this account to be an integral piece of the book of Nehemiah.

abstract: Master of Divinity (M.Div)


title: Babylon Anatomized: Burton's Use of Augustine

contributor:
Roebuck, Graham
English Literature

subject:
Augustine
influence
Burton
attitude
world
humanity
Arts and Humanities
English Language and Literature
Arts and Humanities

abstract:
This dissertation argues that the works of Augustine, especially the City of God and the Confessions, serve as a major source and influence upon Burton's The Anatomy of Melancholy. Burton's attitudes towards the world, humanity, and his sources can be seen to derive in part from Augustine's attitudes on these subjects. Especially, Burton shares with Augustine a form of scepticism this dissertation defines as 'Augustinian Scepticism', which is qualitatively different from the dawning scientific-rationalist scepticism of, for example, Descartes. Though this form of scepticism could be defined as dogmatism, as its rigorous negativity never extends to the grounds of faith, it is still the source of much of Burton's attitude towards the world, his reader and his material throughout the Anatomy. Burton's elenctic rhetorical strategies especially, wherein he collapses all sides of an argument to create seeming chaos in the sublunary world, can in large part be traced to his reading of, and use of, Augustine and avowedly Augustinian thinkers such as Melancthon, Nicholas Cusanus and Agrippa.

Although critics such as Fish, Fox, Babb and Thompson deny an Augustinian influence in Burton's Anatomy, this dissertation argues against their positions. The argument presented employs a method of close, comparative readings, examining key passages of the Anatomy in the light of Augustine's City of God, the Confessions, and other works. Passages wherein Burton cuts closest to his submerged themes of redemption and salvation, abandoning the persona of Democritus Jr. in favour of his persona as Burton the Divine-Physician, (a symbolic persona drawn directly from Augustine), are especially examined. Through a focus on Burton's religious themes, a direct parallel with Augustine is discerned. and it is argued that Augustine has an influence on both style and substance in the Anatomy. Although Augustine is by no means the only, or even dominant influence on the Anatomy, Augustine would appear to play a much larger role in Burton's moral and spiritual thought, especially in Burton's scepticism towards the world, human knowledge and human endeavour, than has previously been acknowledged.

abstract: Doctor of Philosophy (PhD)


title: Some Fibred Knots with Bi-orderable Knot Groups

contributor:
Nicas, Andrew
Mathematics and Statistics

subject:
knots
orderability of knot groups
Alexander polynomial
special polynomial
Linnell
Rhemtulla
Rolfsen
Mathematics
Physical Sciences and Mathematics
Statistics and Probability
Mathematics

abstract:
This project aims to give an overview of knots, orderability of knot groups, and to construct knots for which the knot groups enjoy some nice properties.

To accomplish this, we first present some preliminary results concerning knots and knot groups. We then introduce the Alexander polynomial, and explain the idea of a special polynomial originally introduced by Linnell, Rhemtulla and Rolfsen. By investigating the conditions on a special polynomial, we classify all the special Alexander polynomial of fibred knots of degree less than 10. Finally we construct examples of fibred knots which have a special Alexander polynomial.

abstract: Master of Science (MS)


title: Caught Between Worlds: An Ethnography of Western Tibetan Buddhists in Toronto

contributor:
Rethmann, Petra
Anthropology

subject: Anthropology Anthropology

abstract:
The development of Buddhism in the West as a vital and viable religious path is currently in process. Buddhism has become increasingly visible in mainstream popular culture, and multiple images and conceptions of Buddhism and Buddhists are relatively common. As Buddhism becomes more personally, philosophically, and spiritually relevant to an increasing number of Westerners, to ask the question, "Who are Buddhists?" in the West elicits responses that may be complex, nuanced, and even contradictory. This research explores the ambiguities and the assumptions surrounding popular and scholastic understandings of "Western Buddhists" in Canada.

Focusing on narrative accounts of men and women practising Tibetan Buddhism in Toronto, this thesis will examine the reasons and motivations underlying the contemporary interest in Buddhism. Further, I argue that these reasons and motivations are themselves influenced and shaped by the representation of Buddhism in the West as a textually based, genderless, and timeless tradition. I propose that within any response to the question "Who are Buddhists?" is a matrix of meaning, underpinned by a number of dualities in dynamic tensions between male and female, monastic and lay, the individual and the communal, doctrine and social reality, religion and spirituality, and Buddhist and non-Buddhist.

My research will help explicate the emergence of new religious ideas in Canada, and will contribute to the understanding of an emerging "Western" form of Buddhism as the tradition struggles to become increasingly active in Western socio-cultural contexts. This thesis is one of the first ethnographic accounts of the everyday relgious lives of "Western Buddhists" in which participants have an active voice in the research process. It is also one of the few accounts of Buddhism in the West to come out of Canada, and could provide the basis for more nuanced investigations of the emergence of a "Western Buddhism" in general.

abstract: Doctor of Philosophy (PhD)


title: Radiosensitization of Anoxic Mammalian Cells

contributor:
Skarsgard, L. D.
Biology

subject: Biology Biology

abstract: The purpose of the work described in this thesis was to (a) better understand the mechanisms of chemical radiosensitization of mammalian cells so that the most effective compounds may be selected for radiotherapeutic use, and (b) to possibly explain the failure of early attempts to sensitize mammalian cells in vivo using chemical radiosensitizers. The effect of triacetoneamine N-oxyl (TAN) and several electron-affinic compounds on the colony forming ability of mammalian cells irradiated at both high and low cell concentrations was studied. A possible mechanism of sensitization for TAN was proposed.

abstract: Doctor of Philosophy (PhD)


title: Transport Phenomena and Blood Platelets

contributor:
Feuerstein, I.A.
Chemical Engineering

subject:
Chemical Engineering
Chemical Engineering

abstract:
This thesis contains four studies of transport phenomena and blood platelets.

The initial stage in thrombus formation is platelet adhesion to a foreign surface: platelets diffuse to the surface and then bind to it. Experiments were performed to examine the influence of haematocrit, platelet concentration, shear rate and drugs upon platelet diffusivity, the platelet wall binding rate constant and the saturation level of platelet adhesion to the surface. The level of platelet adhesion to collagen coated glass tubes were determined by measuring the axial distribution of 51Cr-γ-ray emissions from adherent 51Cr labelled platelets. The results demonstrate that the model of Grabowski et al (1972) adequately describes platelet adhesion to foreign surfaces, that platelet adhesion obeys intermediate kinetics, that the plasma skimming layer can be ignored and that platelet diffusivity is enhanced by the complex motion of red cells. An explanation for contradictions in the literature regarding the effect of drugs upon adhesion is suggested.

A design for data collection and analysis was devised for experiments in which the distribution of tracer in multicompartment systems is followed. The design requires the provision of multiple responses and analysis with a Bayesian multivariate technique. It deals with the problems of lumping and ill-conditioning inherent in descriptions of tracer distributions. The design proved successful in characterising the exchange of serotonin between the granules and cytoplasm of rabbit platelets and their surrounding medium in in vitro experiments using washed rabbit platelets.

In vitro, serotonin is freely exchangeable between platelets and their surrounding medium. To describe the potential behaviour of platelet serotonin in vivo, models were devised and fitted to the data resulting from dual label, 51Cr and 14C-serotonin, survival curves. The simplest model that adequately described the data was one in which serotonin was assumed to exchange at a finite rate between circulating platelets. The exchange rate constant from platelet to surrounding was similar to that determined in vitro.

The behaviour of adenine nucleotides in vitro and in vivo have been investigated experimentally (Reimers et al, 1975b). The in vitro exchange of adenine nucleotides between a metabolic pool and a granule pool is adequately described by first order kinetics. This information was used in a model that was fitted to data from adenine nucleotide survival and release studies. No significant metabolism or release of platelet adenine nucleotides was found in vivo.

abstract: Doctor of Philosophy (PhD)


title: The Hydroelastic Vibration of a Hydraulic Swing Check Valve

contributor:
Weaver, D. S.
Mechanical Engineering

subject:
Mechanical Engineering
Mechanical Engineering

abstract:
The purpose of this thesis is to discover the mechanism of excitation and methods of alleviation of self-excited vibrations in a swing check valve following rapid pump shut-down. The problem was first encountered when the valve manufacturer incorporated an adjustable spring-damper into the original design to prevent its violent slamming. Tests on the modified design showed that, rather than eliminate the slamming, the valve disc bounced several times on its seat at a well-defined frequency. With increased damping the number of oscillations as well as the amplitude increased while the frequency decreased. For sufficiently high damping a stable limit cycle oscillation is established. This limit cycle oscillation continued until the valve pivot shaft pins failed. These vibrations are clearly hydroelastic in nature, the oscillations being perpetuated through a transfer of energy from the fluid flow.

A two-dimensional geometrically-similar model of the valve was constructed with perspex sides for flow visualization. A central portion along the base of the model was also laminated with perspex to allow the projection of a collimated sheet of light. Aluminium powder tracer preparation was injected into the flow and cine-photography of the flow during vibration carried out. In addition, dynamic measurements of upstream and downstream pressures, valve angular displacement and the load on the damper arm were synchronized with the films. The data collected in this way for a number of restraining spring rates and initial spring deflection angles allowed a detailed stability map of the valve's dynamic behaviour to be plotted. The essential characteristics of the instability observed in the model are the same as those found in the prototype valve tests although the model was not scaled dynamically. This was necessary in order to guarantee the structural integrity of the model over the long period of tests.

The results of the research show that there is a sudden increase in the hydrodynamic closing load as the valve approaches its seat, primarily as a result of the changing discharge characteristics. Although upstream and downstream waterhammer waves are produced as the valve slams onto its seat, the valve responds only to the pressure difference across it. It remains closed until this pressure difference reduces to the point where it either cracks the valve open or allows the damper spring to pull it open. On the opening part of the vibration cycle the hydrodynamic closing load is substantially lower than the load at the same angle during closing. This hysteretic effects shows that there is a net energy input from the fluid during each cycle and the motion is perpetuated.

Tests on the model further show that if the damping spring is stiff enough to eliminate the slamming, either the valve will never close or it will exhibit limit cycle oscillations. Clearly, neither alternative is acceptable. Based on the aforementioned results, it was realised that another possible means of alleviating the problem is to alter the discharge characteristics of the valve at small angles of closure by suitable changes in geometry. In the second part of the thesis, a number of such changes were made in the model and the experiments repeated. It was discovered that by making the rate of change of discharge a more gradual function of the valve closure angle, the dynamic instability in the model could be entirely eliminated.

abstract: Doctor of Philosophy (PhD)


title: Shaping the Moral Imagination of Caregivers: Disability, Difference & Inequality in L'Arche

contributor:
Cooper, Matthew
Anthropology

subject: Anthropology Anthropology

abstract:
The ethnography explores moral dimensions of the motives and experiences of L'Arche caregivers in Canada. L'Arche is an intentional faith community, whose mission is to be a sign of hope and love to the world through creating homes and relationships with people with intellectual disability. I historicize the evolution of L'Arche by identifying the confluence of socio-political, economic, and religious factors through which it emerged. Related to this is how the founders reframed the negative overtones of difference and disability, and developed a radical ethic and model of caregiving. To illuminate how radical that model was, and still is, I situate it in relation to mainstream histories of care based on a deficit model of disability. I also illustrate the cultural construction of disability historically.

The narratives of L'Arche caregivers point to what it means for them to live and work in L'Arche. These narratives reveal a blend of self-interest and altruism, tied to identity, morality, spirituality, and community. While some of their motives reflect their desire to contribute to broader socio-political change, I show that in the end these aspirations are not finding sufficient outlets in today's inward-focused communities.

The caregivers learn this radical approach through a process of enculturation into the local moral world of L'Arche. This transforms their moral perspective on difference, disability, and care, and makes them suitable reproductive agents. I deconstruct this process into key strategies and illustrate with ethnographic data. The constructive and negative potential of each aspect of the cultural system is dealt with from assistants' perspectives. I analyse the key fruits of L'Arche; the mutual relationships between caregivers and people with intellectual disabilities. I discuss traditional barriers against such relationships and present fieldwork examples of negotiating relations in practice, across the capacity and power imbalances inherent in them.

abstract: Doctor of Philosophy (PhD)


title: A Solubility Model for Deposition of Stratiform Massive Sulphide Deposits, New Brunswick, and its Relation to the Distribution of Gold and Palladium

contributor:
Crocket, J. H.
Geology

subject: Geology Geology

abstract:
Gold and palladium concentrations have been determined in sulphide ores and host rocks of the Caribou, Brunswick No. 12 and Heath Steele mines, New Brunswick, by neutron activation analysis. Gold contents vary from 100 to 6000 ppb in the ores. Gold correlates positively with lead and zinc in the Caribou and Brunswick No. 12 deposits, but is uncorrelated with base metals in the Heath Steele B -1 orebody. Palladium contents range from 3 to 0.1 ppb and, in contrast with gold, show no correlation with base metals in any of the mines. Thus, transport and depositional processes controlling palladium distribution remain obscure. An analysis of the variation of gold content of separated minerals found in replicated analyses, suggests that the dominant mode of occurrence is the native metal.

Based on work by Sato (1972b, 1973), a comparison with the Kuroko deposits and analytical data collected by the author, a syngenetic model for metal distribution in the New Brunswick ores has been developed. On the basis of such features as shape, lamination, initial grain size and metal ratios, it is suggested that these latter ores were formed at lower temperatures and from solutions of higher density than the Kuroko deposits.

The correlation of gold with lead and zinc is similar to that found in the Kuroko and is inexplicable in terms of chlorocomplexing (Helgeson, 1969) for either Kuroko or New Brunswick stratiform deposits. It is concluded that gold sulphide complexes are the most likely species responsible for gold solubility and transport in the ore solutions which formed these deposits.

The zoning of gold from low concentrations in copper-rich ore to higher concentrations in lead-zinc ore is thought to reflect gradual saturation of an ore solution with respect to gold in the waning states of sulphide precipitation. Decreasing temperature, fugacity of oxygen and molality of aqueous sulphide, together with increasing ore solution pH, are primarily responsible for attainment of saturation with respect to metallic gold.

abstract: Doctor of Philosophy (PhD)


title: Coprecipitation with nickel cycloheptanedionedioximate

contributor:
Dr. O.E. Hileman, Jr.
Chemistry

subject: Chemistry Chemistry

abstract:
The development of a new PFHS (precipitation from homogeneous solution) method for the determination of nickel is reported. Cycloheptane-dionedioxime was generated from 1,2-cycloheptanedione and hydroxylamine in solution in the presence of nickel ions to produce nickel cycloheptane-dionedioximate crystals. The reported method of synthesis of 1,2-cyclo-heptanedione was modified in order to obtain a pure product.

We product the results from kinetic studies on the nickel cycloheptane-dionedioximate precipitation reaction both in the absence and in the presence of two foreign ions, cobalt (II) and copper (II).

The developed PFHS method was useful in studies on the coprecipitation of cobalt and copper with nickel cycloheptanedionedioximate. Distribution diagrams were prepared using the two classical distribution laws for both systems studied. None of the limiting laws provided a satisfactory explanation of the observed data. Deviations observed in the behaviour of homogenous distribution coefficient and logarithmic distribution coefficient, D and λ, are interpreted in terms of kinetic parameters. The functional relationship between D and λ and the rate of nickel cycloheptanedionedioximate precipitation is reported.

A kinetic model, which relates the rate of precipitation per particle and the distribution coefficients was also tested in both co-precipitation systems. The model was found to be useful only to a limited extent.

abstract: Doctor of Philosophy (PhD)


title: The Evaporation from Three Different High-Latitude Surfaces

contributor:
Rouse, W. R.
Geography

subject: Geography Geography

abstract: This study examines the evaporation from a lichen-dominated upland ridge, a swamp and a shallow lake in the Hudson Bay lowlands evaluated by the energy-budget and equilibrium model approaches. Energy-budget calculations reveal that on average 54, 66 and 55 percent of the daily net radiation is utilized in the evaporative process over the ridge, swamp and lake surfaces respectively. For the ridge half-hourly and daily values of evaporation were approximated closely by equilibrium estimates, while for the other surfaces close approximation was achieved by the Priestley and Taylor (1972) model where the ratio of actual to equilibrium evaporation equals 1.26. A simple model, expressed in terms of incoming solar radiation and the screen height air temperature, is developed for each surface from the comparison of actual to equilibrium evaporation. Tests of the models at different locations indicate that the actual evaporation can be estimated on a daily basis within 6 percent for dry upland and saturated lowland swamp surfaces, while for shallow lakes, the evaporation can be determined within 10 percent over periods of two weeks.

abstract: Doctor of Philosophy (PhD)


title: Rhenium and Osmium in Some Canadian Ores by Neutron Activation Analysis

contributor:
Schwarcz, H.P.
Crocket, J.H.
Geology

subject: Geology Geology

abstract: Neutron activation analysis procedures have been developed for the determination of rhenium and osmium in common metallic minerals from wide variety of ore deposits. The Os method is based on double distillation, solvent extraction and precipitation of the metal. The Re method uses double anion exchange, solvent extraction and precipitation. The accuracy of the methods were checked against molybdenite and Cu-Ni matte standards. A literature survey of the rhenium and osmium is presented and the geology of the deposits is presented. The analytical results are discussed in terms of the current feasibility of dating ores by the Re-Os method, and their geological significance.

abstract: Doctor of Philosophy (PhD)


title: Studies on the Control of Gene Expression of rpoS and its Regulon in Escherichia Coli

contributor:
Schellhorn, H.E.
Biology

subject: Biology Biology

abstract:
Many factors regulate the expression of rpoS at the levels of transcription, translation, proteolysis and RpoS activity. However, the relative importantance of different levels of control is not well understood. By manipulating rpoS expression, we will better understand environmental adaption responses. The first part of the study suggests that RpoS mutants can be selected using minimal media supplemented with succinate. We isolated 20 mutants that had the ability to grow on succinate as the sole carbon source. All mutants exhibited lower levels of RpoS function or osmY transcription. Sequencing and alignment analyses confirmed that all isolated succinate utilizing mutants possessed mutated alleles of the rpoS gene. Succinate transvertion mutant can revert to an rpoS wild type phenotype under sub-optimal conditions.

The second part of the study has demonstrated that inducible rpoS antisense RNA complementary to rpoS mRNA can inhibit the expression of RpoS in both exponential and stationary phases and can attenuate expression of the rpoS regulon in E. coli.

The final part of the study artificially expressed RpoS protein and its regulon in both exponential and stationary phases. rpoS mRNA can be induced at an early stage of cell growth when RpoS levels are normally extremely low (i.e., in early exponential phase) and can activate the expression of the RpoS regulon in exponential phase and stationary phase. Our results showed that controllable levels of RpoS could regulate the expression of rpoS and RpoS-dependent genes indicating RpoS expression is sufficient for expression of the regulon in exponential phase.

abstract: Doctor of Philosophy (PhD)


title: Dynamic Real Time Control of the Activated Sludge Process Using Step Feed

contributor:
Murphy, K. L.
Chemical Engineering

abstract:
This study examined at pilot scale the application of dynamic control with a step feed activated sludge process for control of effluent quality. Computer simulation and pilot studies were used to develop a process control strategy involving the Specific Oxygen Utilization Rate (SCOUR). This control was applied using a real-time minicomputer system. Comparisons were made to a single compartment completely-mixed process operated in parallel to the controlled system.

The control strategy attempted to maintain SCOUR at a desired setpoint in the final compartment of a three reactor step feed system. Optimal influent contacting patterns were continuously calculated for the first and third compartments to satisfy the control objective. Unique optimization was not possible if the flow distribution was made to three compartments.

Using a SCOUR setpoint of 15 mgO₂/g MLSS-h filterable organic carbon effluent data suggested that a reduced effluent variability can be obtained during high loading periods. At low loadings when SCOUR control was limited, no improvement of effluent TOC was obtained.

With SCOUR control, consistently higher effluent solids concentrations were observed. High effluent suspended solids concentrations for the controlled system were probably caused by the inefficient oxygen transfer by the diffuser aeration system in the pilot plant.

abstract: Master of Engineering (ME)


title: Energy Exchange on a Melting Glacier

contributor:
Davies, J.A.
Geography

subject: Geography Geography

abstract:
Although methods of evaluating various energy exchanges between the atmosphere and the earth's surface are available, a need for additional knowledge about the turbulent transfer of sensible and latent heat on a melting glacier is recognized. The micrometeorological investigation described in this study is a response to this need. A measurement programme was conducted during the summer of 1971 on Peyto Glacier, Alberta. Data collected include net radiation, melt energy, and the atmospheric parameters, wind speed, temperature and vapour pressure, at several levels above the ice.

Emphasis is placed upon computing sensible and latent heat exchange from profiles of the atmospheric parameters. This is approached through an examination of boundary layer thickness, stability relationships in the boundary layer, and surface roughness lengths. Since all temperature profiles showed inversions, the results characterize stable conditions, where turbulence is dampened. In addition, katabatic flow results from the slope of the glacier.

Turbulent boundary layers in stable flow are known to be relatively thin, but an unexpectedly thin boundary layer, approximately one metre thick, is found over the glacier. The thinness of this layer is attributed to katabatic control of the flow. Deviation from the adiabatic profile form due to stability is adequately described by a log-linear framework, a finding which agrees with other work. However, is is accompanied by an inequality of transfer coefficients, that for heat exceeding that for momentum. This has not been reported previously. A tentative hypothesis is advanced to explain this. Contrary to previous glaciological opinion, the wind profile roughness length is found to be smaller than that of the temperature profile. This is explained using results of other work on other surfaces.

A bulk transfer procedure is chosen as the most suitable method of evaluating the turbulent fluxes. The procedure is strengthened by the findings of this study. It is used to obtain half-hourly estimates of sensible and latent heat exchange which appear to be reasonable. Short-term variations in the meltwater, hydrograph are found to be closely controlled by the net radiative flux, but daily totals indicate that the sensible heat flux is also an important energy source. Latent heat transfer by the water vapour flux between the atmosphere and the surface is small.

The contribution of this investigation to establishing the link between glacier hydrology and climate is indicated.

abstract: Doctor of Philosophy (PhD)


title: Dynamics of Lateral Stripe Formation in the Zebra Fish, Brachydanio rerio

contributor:
Dingle, A. D.
Biology

subject: Biology Biology

abstract:
This investigation was concerned with the formation of the lateral stripe in the zebra fish, Brachydanio rerio. This stripe, which consists of a row of anterior-posteriorly oriented melanophores, extends along the body in the horizontal skeletogenous septum over about a 25 somite span.

It was found that individual three day old fish showed differences in the numbers and arrangements of melanophores in the stripe while in eight day old fish the stripes were more nearly equivalent. Analysis of the regulatory mechanisms which control cell number and placement was done by extirpating the appropriate melanophores at defined stages in the first eight days of development. When individual cells were removed at three days, the experimentally produced defect was regulated 85% of the time. When all the melanophores present at three days were extirpated in fish with large numbers of these cells, approximately 90% of the total number of eight day melanophores seen in control fish was present at eight days.

A scheme of pattern development involving two controls has been proposed for the early lateral stripe of the zebra fish. The first is the excluding effect that the three day cells have on the appearance of second wave melanophores (position control) and the second is the control of cell number, or numerical regulation. These two processes work together to ensure that the melanophores will be evenly distributed along the stripe in the appropriate numbers.

Observations were also made of later fates of the eight day lateral stripe melanophores. These cells can reorient out onto the flank to help contribute to the juvenile stripe or can remain stranded in the horizontal skeletogenous spetum either as deep or more superficial cells in which reorientation is not complete. They can also undergo what appears to be a programmed type of cell death if they reorient onto the flank but do not successfully migrate into the forming juvenile stripe. This latter process would ensure that pattern aberrations do not occur.

This study shows that in the development of the zebra fish melanophore pattern there is a delicate interplay between cell position and number and that early lateral stripe melanophores may have important roles to play in further band genesis.

abstract: Doctor of Philosophy (PhD)


title: A Thermo-Mechanical Force Model for Machining Hardened Steel

contributor:
Elbestawi, M. A.
Mechanical Engineering

abstract:
The maching of hardened steels is becoming a viable technology. At the inception of the present research, this technology for milling processes was in its infancy. Advancements in cutting tool materials such as poly-crystalline cubic boron nitride (PCBN) have enhanced the ability to machine these difficult to cut alloys. The machining of hardened tool steels have been explored in the recent literature to a great extent because of the possible gains and benefits this technology has to offer. Near net shape manufacturing can become a viable technology and save the die and mold industry considerable investment by reducing the lead time for production of dies and molds.

In this thesis, an experimental investigation is presented regarding the optimal process parameters that make high speed hard machining a viable technology. The experimental investigation shows that hard machining of AISI H13 (55 HRc) is possible, and is an extremely effective technology if the proper conditions are used. Because of the nature of hard machining, the fundamental aspects of chip formation, tool wear and life is explored through a detailed investigation. It was confirmed that the ball milling of hard materials produce segmented saw toothed chips even at low chip loads for specific cutting conditions. It was noticed that the chip morphology was very repeatable and consistent and therefore formed a preliminary basis for the modelling strategy. Tests were also performed on hardened AISI D2 tool steel (62 HRc), which showed that this material in its hardened state challenges the ability to machine this material in the fully hardened state. The primary tool failure modes are outlined and a detailed analysis of the chip formation mechanisms is reviewed.

Owing to the difficulty associated when machining hardened AISI D2 tool steel, the development of an analytic force model was attempted. The modelling methodology required a correlation of the flow stress (the mechanical response of the material) with the cutting conditions in the form of kinematic parameters derived from chip morphology. The hardened material was characterised using high strain rate ballistic impact tests (using the compressive split Hopkinson pressure bar) in a punching shear configuration. This configuration was chosen as it represented the shearing process in metal cutting more accurately in terms of strain and strain rate. The tests were modified and performed on the fully hardened tool steel. The ultimate result was a precise representation of the flow stress of the hardened material in shear as a function of the strain, strain rate and temperature where the fitted correlations represented the experimental data with an accuracy of approximately 10%. The temperatures in this part of the investigation exceeded 600 °C with strains in excess of unity and strain rates approaching 50000 s^-1.

Having a correlation of the flow stress of the fully hardened material, the force model was derived using the chip morphology and chip formation kinematics to represent the governing strain and strain rate conditions during machining. The resulting formulations allowed for a time domain orthogonal machining simulation represented by specific inputs such as cutting speed and feed rate. The orthogonal formulation was verified against experimental data and showed good correlation with observation.

The orthogonal formulation was extended to the ball milling process (an oblique cutting configuration) to test the validity of the force model. Good correlation was realized between the experimental and predicted results. The ball milling process challenged the validity of the force model by applying the modelling strategy to small chip loads and low cutting speeds. The predicted results also rationalized the tool failure mode that was observed in the ball milling investigation.

abstract: Doctor of Philosophy (PhD)


title: Experiments and Modeling of Pulp Mat Formation

contributor:
Hrymak, Andrew
Pelton, Robert

subject: Engineering Engineering

abstract:
In this dissertation, new insights into dispersed air, surfactant and defoamer effects on pulp mat formation in brownstock washing are described based on extensive experimental research. Observations of bubble behavior and channel formation are used to explain the relationship between the presence of dispersed air and the resulting low water drainage rates from the pulp pad. The work provides new understanding of the mechanism of dispersed air effect on pulp washing.

A new pulp mat water permeability model is also included in this dissertation. The model covers a wider pulp fiber concentration range than previous models in literature.

A systematic experimental investigation of pulp mat formation from dilute suspensions provides concentration profiles and mat thickness as a function of time. Dynamic fiber concentration profiles along the mat formation direction were inferred from standard images using a grayscale analysis calibrated against a set of known concentrations. A modified semi-empirical filtration model, based on the work of Tiller et al, was applied to compressible porous pulp fiber mat formation, and fits the experimental results very well. With this newly developed model, it is easy to calculate the capacity of a pulp washer at varied operating conditions. This model can be used for process optimization and control and make it possible to further improve the pulp washer efficiency.

abstract: Doctor of Philosophy (PhD)


title: Development of Three-Dimensional Turbulent Wall Jets

contributor:
Ewing, Dan
Mechanical Engineering

abstract: Detailed flow field measurements were performed to investigate the development of the three-dimensional wall jet, the effect of initial conditions on the development of wall jets and the evolution of the large-scale vortex structures that causes the large lateral growth rate in the flow. Single-point measurements in the wall jet exiting a contoured nozzle indicated that there were two regions in the intermediate field 10 ≤ x/D ≤ 40. The flow underwent a significant change in the region 10 ≤ x/D ≤ 20 as it adjusted to the wall. The changes of the profiles of the moments and the reorientation of the regions of the mean streamwise vorticity slowed down in the region beyond x/D=20 and were not apparent by x/D=40. The comparison of measurements of wall jets exiting the contoured nozzle and the fully developed long pipe indicated that changes in intial conditions do affect the jet half-widths and the decay of the maximum streamwise velocity through near and intermediate fields. The differences in growth rates of wall jets, profiles of moments and contours of the mean streamwise vorticity in the two jets were reduced in the region after x/D=10 and were not apparent in the region beyond x/D=20 - 30. Measurements of two-point, two-time correlation of the streamwise fluctuating velocity indicated that the large-scale vortex structures that consist two pair of horseshoe vortices in the flow continued to develop throughout the intermediate field. In particular, the inner vortex structures were induced towards the wall by the outer structures and the legs of the outer structures inclines relative to the streamwise direction as the flow evolved downstream. Measurements also indicated that the flow below the outer region of the streamwise vorticity was laterally convected faster than the outer vortex structures.

abstract: Doctor of Philosophy (PhD)


title: Social Capital and Environmental Risk: Understanding Responses to Adverse Air Quality in Hamilton-Wentworth

contributor:
Elliott, Susan J.
Geography

subject: Geography Geography

abstract: This thesis investigates civic action around environmental concerns, using the issue of air quality in Hamilton, Ontario, as a case study. There is growing emphasis in the literature on citizen participation in environmental and health policy. However, our understanding of the factors which motivate or hinder citizen action around local environmental issues is at best limited, particularly with respect to the roles of social context and social captial in facilitating collective action. This research focusses on the need to better understand environmental action-taking by: documenting intra-urban variation in air quality perception, concern, and action in the City of Hamilton; identifying factors related to both predisposition and capacity to take action around air quality; and exploring how these factors, particularly social capital, influence the relationship between environmental risk perception, concern, and action. A combination of qualitative and quantitative methods were used in this research. In-depth interviews (n=21) conducted with residents of an area experiencing poor air quality illustrated the specificity of lay understandings and concerns about exposure to air pollution, and indicated that social capital played a central role in the development of civic environmental action. A quantitative survey, administered to a random sample of households in Hamilton (n=512, stratified by area of residence), investigated environmental perception and concern, individual and social network characteristics, and environmental action. Results indicated that, while variation between areas was observed in terms of aggregate individual characteristics and perceived exposure to air pollution, little geographic variation in social network characteristics and perceived exposure to air pollution, little geographic variation in social network characteristics, air pollution concern, or environmental action was observed. Predictors of a variety of environmental actions were identified through logistic regression, and the results suggested substantial differences between types of action. Further, factors related to social networks generally played a larger role in environmental action-taking than socio-demographic factors.

abstract: Doctor of Philosophy (PhD)


title: The Relationship Between Diversity and Stability in Tropical Rock Pools

contributor:
Kolasa, Jurek
Biology

subject: Biology Biology

abstract:
This dissertation examines the relationship between diversity and stability in aquatic rock pool invertebrate communities. Previous tests of the relationship between diversity and stability have suggested that diversity stabilizes communities properties but either destabilizes or is unrelated to population properties; however, a comprehensive test of the relationship between diversity and stability has not previously been conducted in aquatic ecosystems. I used two approaches to examine diversity-stability relationships in rock pools. First, I used time series data of population and community densities collected on 49 rock pool communities over 8 years, and second, I experimentally manipulated diversity and nutrient conditions in rock pool container habitats.

I found that diversity was negatively related to community variability in both natural unmanipulated rock pools and experimental rock pools consistent with the diversity-stability hypothesis. However, the stabilizing effect of diversity was modulated by environmental conditions. In natural unmanipulated rock pools strong correlations between diversity and community variability were identified in abiotically stable rock pools and temporary rock pools that were subject to frequent desiccation events. In contrast, there was no relationship between diversity and community stability in rock pools with variable abiotic conditions or permanent rock pools which were not subject to desiccation events.

That environmental conditions might modulate the relationship between diversity and stability was further confirmed experimentally. In experimental rock pools the responses of community and population stability to different diversities depended on nutrient conditions. Diversity stabilized both community and population densities in oligotrophic rock pools but not in mesotrophic or eutrophic rock pools. The stabilizing effect of diversity on community density supports previous studies in other ecosystems, however, this is the first study to show a stabilizing effect of diversity on population densities.

The results of this study suggest that under some conditions stability is dependent on diversity, however there is no necessary relationship between diversity and stability in rock pool communities. Furthermore, contrary to the general conclusions drawn from mathematical models and experimental studies in plant communities, populations may be stabilized rather than destabilized by diversity depending on the system under consideration.

abstract: Doctor of Philosophy (PhD)


title: Film thinning in oil/water coalescence

contributor:
Woods, D.R.
Chemical Engineering

abstract:
This thesis is a study of the effect of surfactant on the film thinning behaviour of small, single droplets coalescing at a planar interface in oil/water systems. There are two major parts in this thesis. The first is the mathematical modelling of film thinning, and the second is the experimental measurement of the variation of film thickness during thinning.

The mathematical modelling consists of:

(i) the development of a film thinning model in which the interface mobility is calculated and not assumed arbitrarily,

(ii) the numberical solution of this film thinning model based on a polynomial representation of the pressure in the film,

(iii) the extension of the parallel disc model to describe the thinning at the barrier ring for uneven thinning, by allowing the interfaces to have varying degrees of partial mobility, and

(iv) the algebraic analysis of a postulate for the conditions for even and uneven thinning, based on the assumption that the pressure in the film is a parabolic function of the radial distance. To verify these models, their predictions are compared with experimental observations.

In the experimental part, the effect of additions of palmitic acid and the effect of drop size and bulk interface age on the film thinning behaviour of toluene drops have been investigated using the white light interference technique. A novel drop forming technique has been developed, by which one drop forming nozzle can be used to form drops of different sizes without piercing the bulk interface; this technique eliminates the possibility of surfactant transfer between the bulk and drop interfaces.

New observations of film thinning behaviour are reported. These are the uneven thinning pattern that occurs when both the drop and bulk interfaces have the same surface concentration, and new thinning patterns which occur when drops are released to the bulk interface in rapid succession.

abstract: Doctor of Philosophy (PhD)


title: Self-Tuning and Adaptive Control of a Pilot Plant Fluidized Bed Reactor

contributor:
MacGregor, J.F.
Chemical Engineering

abstract:
A pilot plant fluidized bed reactor in which complex and highly exothermic catalytic hydrogenolysis reactions are taking place, is being used to investigate the computer control of temperature, conversion and selectivities in such reactors. The process is highly nonlinear, characterized by asymmetric dynamics and considerable change in catalyst activity. Moreover, a deadtime of 360 s is introduced by an on-line process gas chromatograph employed to obtain the composition measurements. As a result, the cascade control system comprising a proportional-integral controller for reaction temperature in the inner loop and a Dahlin controller for propane selectivity in the outer loop was reported in previous works to have performed well in certain regions of operation at a given time but revealed very oscillatory and nearly unstable performance in other regions or at different times.

This nonlinear behaviour of the reactor is further investigated. It is found that by better matching the process response characteristics and by detuning the Dahlin controller, this unstable oscillatory behaviour of the cascade control system can be overcome and acceptable performance can be achieved over a wider range of operating conditions. Later, self-tuning adaptive controllers are tried in an attempt to better account for the changing gains and time constants of the nonlinear process, as well as for the time-varying catalyst activity. The cascade control scheme with Dahlin and Self-tuning regulator (STR) demonstrated excellent performance. Finally a double STR configuration for both the inner and outer loops in carried out. Problems associated with this implementation are discussed and possible improvements suggested.

abstract: Master of Engineering (ME)


title: Suppressor-sensitive mutants of Bacteriophage PBS2

contributor:
Takahashi, I.
Biology

subject: Biology Biology

abstract: Suppressor-sensitive mutants of Bacillus subtilis phage PBS2 were isolated from chemically mutagenized lysates. These mutants were found to comprise thirty-eight distinct complementation groups. Mutants affected in DNA synthesis and host cell lysis were identified and characterized. Two complementation groups were found to be involved in the appearance of the phage-induced DNA polymerase activity. A linear genetic map was constructed based on the results of two and three-factor genetic crosses and linkage tests.

abstract: Doctor of Philosophy (PhD)


title: Aspects of the ecology of coastal tundra raised beach ridges in Northwestern Ontario

contributor:
Kershaw, K.A.
Biology

subject: Biology Biology

abstract:
The structure of lichen dominated vegetation is described within a series of raised beach ridges found along the strip of coastal tundra in northwestern Ontario. The patterns of distribution of the most abundant species correlated with the topographic influences of individual beach ridges more than with the influences of the general developmental sequence of vegetation from the coast of Hudson Bay, inland.

The importance of topography to the structure of this vegetation was examined by comparing ridge top and bottom positions of raised beach ridges in terms of edaphic factors, snow cover and microclimatic factors. A new experimental system was developed to test for adaptation of net photosynthetic rates in the lichens Alectoria ochroleuca ( Hoffm. ) Massal. and Cetraria nivalis (L.) Ach. to the contrasting ridge surfaces from which they were collected. Morphological adaptations to these beach ridge surfaces were also examined.

Seasonal patterns of net photosynthesis in both species showed that intra and interspecific differences in seasonal acclimation were important to the observed patterns of distribution in the field. Thallus morphology was found to provide optimal water relations for photosynthetic production. Experiments showed further that the potential for control of evaporative loss is present in lichens.

This study shows that the patterns of distribution observed in the field, are consistently related to the topographic relations of individual beach ridges. These patterns are also consistent with both the physiological and morphological requirements exhibited by the plants, and with the defined physical characteristics of the surfaces on which they grow.

abstract: Doctor of Philosophy (PhD)


title: Phonons in Copper at Elevated Temperatures

contributor:
Brockhouse, B. N.
Physics

subject: Physics Physics

abstract:
The technique of inelastic scattering of thermal neutrons offers a versatile, yet powerful, method of observing the spectra of elementary excitations in condensed matter. In this thesis, this technique was used in the determination of the phonon spectra of three metals, using monocrystalline specimens.

The first study concerns the temperature dependence of the phonon spectrum of Cu in the range 20ºC to 1063ºC, i.e. up to 20ºC below the melting point, and in the various directions of high symmetry accessible in a (001) scattering plane. Resolution effects were taken into account in the determination of intrinsic phonon frequencies and linewidths. The results indicate a general softening of the lattice as a function of temperature, the vibrations of transverse polarization being significantly more affected (on a relative basis) than those of longitudinal polarization. Most of the signals have remained observable up to the vicinity of the melting point. A high resolution study of the small wavevector domain was also performed in order to determine the temperature dependence of the (adiabatic) elastic constants in a temperature range inaccessible to the usual ultrasonic methods. Of particular interest is the fact that the T1 branch was found to manifest a peculiarity at the approximate reduced wavevector ζ = 0.2; a careful examination did not reveal any corresponding distinctive behaviour in the linewidth (lifetime). A search for possible manifestations of the Kohn effect at high temperature was also performed at other positions in reciprocal space.

A similar study (extending up to 1050ºC) was also carried on the small wavevector phonons in Pd. It is known, from other workers, that this substance shows a peculiar temperature dependence in the T1 branch, this dependence being opposite to that observed in Cu.

Finally, the third study deals with an unsuccessful attempt to observe a predicted weak Kohn effect in the room temperature phonon spectrum of W.

Technical details concerning the apparatus built for the high temperature measurements are to be found in chapter III following a review chapter on the crystal dynamics of metals and the technique of triple-axis spectroscopy, with particular emphasis on the optimization of experimental variable and the correction of resolution induced effects.

In appendix, various projects not having an immediate relevance to this research are discussed, i.e. triple-axis spectrometer automation by paper tape, compilation of a bibliography covering most of the literature concerning thermal neutron scattering, various computer programmes.

abstract: Doctor of Philosophy (PhD)


title: Rare Earth Elements in the Sudbury Nickel Irruptive

contributor:
Crocket, James H.
Geology

subject: Geology Geology

abstract:
Rare earth elements have been determined by group separation, radiochemical neutron activation analysis in rocks from the main Irruptive, the sub-layer and sub-layer inclusions from the Sudbury Nickel Irruptive, Ontario, Canada.

Rare earth behaviour in layered intrusions in discussed and applied to the Sudbury Nickel Irruptive. The petrogenesis and mutual relationships of the Sudbury rocks are discussed in the light of their rare earth properties.

abstract: Doctor of Philosophy (PhD)


title: Reinforcement Interval and Interresponse Time Reinforcement as Determinants of Response Rate

contributor:
Platt, John R.
Psychology

subject: Psychology Psychology

abstract: Reinforcement may affect responding by strengthening a response so as to increase its frequency of occurrence and by differentiating a response with respect to some of its properties. It has been suggested that response rate is controlled by the strengthening effect of reinforcement on responding and by the differential reinforcement of the time between responses, the interresponse time. The strengthening and differentiating effects of reinforcement on response rate are usually confounded in studies of responding on simple reinforcement schedules. This thesis analyzed the effects of reinforcement interval (a strengthening variable) and interresponse time reinforcement (a differentiating variable) on response rate by independently manipulating them over a range of values. Food-deprived pigeons pecking illuminated disks for food reinforcement were exposed to novel reinforcement schedules which allowed simultaneous differential reinforcement of interresponse times and control of reinforcement interval. With these schedules interresponse time reinforcement was the principal determinant of response rate while reinforcement interval played a secondary role. Although both variables made independent contributions to the determination of response rate, they did not interact over the range of values investigated. This thesis documents the existence of separable strengthening and differentiating effects of reinforcement on response rate and emphasizes the importance of interresponse time differentiation in the determination of response rate.

abstract: Doctor of Philosophy (PhD)


title: The Movable Mosaic: An Inquiry Into the Theory of Reconstruction of Political Reality

contributor:
Novak, D.
Political Science

subject:
Political Science
Political Science

abstract: The dissertation is devoted to the development of a systematic theory of political experience. While this project involves, at first, the synthesis of the pragmatist tradition in political philosophy into a theory of reconstructive empiricism, it also entails the elaboration of this revision of political epistemology into a paradigmatic theory of human action. Using this paradigmatic theory of human action as the basis of analysis, an examination then follows of three generalized modes of political experience, and of the relationship which hold between them.

abstract: Doctor of Philosophy (PhD)


title: Naturalism, Skepticism and Reason in Hume's Treatise

contributor:
Noxon, J.
Philosophy

subject: Philosophy Philosophy

abstract:
This dissertation is primarily concerned with a discussion of Human skepticism. It is divided into two parts:

Part 1 is concerned with interpretative matters. It is shown that Hume's most characteristic skepticism is to be treated as an intimate part of a system which is concerned with the ramifications of an entirely naturalistic account of man. One of Hume's major concerns, it is argued, is with the production of a naturalistic account of reason, and the skeptical elements of Book I are to be seen entirely as either foundations or by-products of this naturalistic account. It is shown that when they are seen as part and parcel of this naturalistic account of reason, the various levels of Humean skepticism can all be recognised as entirely natural and predictable, not as matters in any respect likely to surprise and baffle the reader who is fully acquainted with Hume's purposes.

During the discussion, remarks are made on alternative interpretations of Hume; on the purpose of philosophy; on the significance of Hume of his empiricist first principles; on the "age of reason"; on the significance of Hume's discussion of the natural beliefs and induction; on his approach to the apodeictic; on his problems with philistinism; on the extension of his analysis of reason in the Dialogues, and on his psychologism.

Part II evaluates the various doctrines uncovered in Part I of the dissertation. It is argued that post-Darwinian thought should embrace much of Hume's naturalistic account of reason, but that the Darwinian framework obviates much of the most objectionable aspects of Hume's defense of his account. The inadequacies of some of Hume's skeptical arguments are made clear, and the strengths of his account are brought into relief. The underlying differences between Hume and his opponents on the nature of reason as a "cosmic" principle are discussed, and Hume is shown to be the victor.

During this discussion, remarks are made on the evolutionary significance of reason; on the nature of the "natural beliefs"--or categorical principles; on the justification of induction; on "natural necessity", the meaning of "brute fact" and the attribution of "rationality" to the non-sentient; on the avoidability of Hume's difficulties with philistinism; on the principle of sufficient reason as the supreme rationalist principle, and on the significance of "system" to explanation.

abstract: Doctor of Philosophy (PhD)


title: Dissemination of Heart Health Promotion in Ontario's Public Health System: A Social Ecological Perspective

contributor:
Taylor, S.M.
Geography

subject: Geography Geography

abstract: The research reported in this dissertation examines the dissemination of heart health promotion within the Ontario public health system. It contributes to a relatively new reasearch agenda to understand how to enhance implementation of the new public health; to apply knowledge of effective community- and population-based prevention. Three studies are reported, which extend research conducted in Ontario from 1994 to 1998 as part of the Canadian Heart Health Initiative Ontario Project (CHHIOP). Study one combined diffusion and social ecological theories to examine the dissemination process at the level of the public health system and over a ten year period. Studies two and three examined the implementation stage in more depth, with a view to understand variability across Ontario communites. Study two was a quantitative path analysis to identify determinants of 1997 levels of implementation, and study three was a comparative case study to understand change in implementation from 1994 to 1996. Main data sources were quantitative and qualitative data from CHHIOP. Findings reinforce the need for a systems view of dissemination; that dissemination is a long-term, iterative process; and that organizational capacity building is a vital part of the dissemination process, especially when new practices represent a significant departure from traditional concepts and ways of doing business. The research demonstrates that the interplay of internal organizational factors (e.g. champions, leadership, organizational structure) and external system factors (e.g. research, political priorities, experiences of other jurisdictions, partnerships) helps to explain movement within and across dissemination stages. Findings suffest promising areas for dissemination research, including replicating similar research in other public health systems. Findings also suggest promising strategies to accelerate the dissemination of effective health promotion, including specific strategies to further enhance heart health promotion in Ontario.

abstract: Doctor of Philosophy (PhD)


title: Coolant Void Effects in Neutron Multiplying Media

contributor:
Harms, A.A.
Vlachopoulos, J.
Chemical Engineering

abstract:
Various models of the nuclear reactor system are developed and evaluated in order to provide insight on the fundamental phenomena involved in the coolant void effect as a guide to future simulation studies and experimental design.

The mathematical description of the fundamental phenomena and consideration of the macroscopic physical characteristics define models for the neutron flux density and the coolant void fraction for the case of boiling-light-water nuclear reactors. Experimental comparisons are made whenever possible to evaluate the effectiveness of those models. The two-group neutron diffusion model and Hancox's void model were found necessary to describe the steady state behaviour of the nuclear reactor cell. The errors and limitations of present day models and techniques are delineated; the directions for improvement are also indicated. In general, it was found that independent experimental estimates of the fundamental parameters are needed to replace the current reliance on extensive experimental model correlations. In this way the need for expensive prototypes can be eliminated.

A temporal transformation of the general space-time neutron equations is developed to facilitate their solution by standard numerical techniques. It was found that the computation time can be reduced over threefold for transient control problems.

The coupling of the fluid model and the neutron flux model proves most interesting and shows that coolant voiding can have a profound effect on both the steady state and the transient behaviour of nuclear reactors. It is also shown that errors in present day techniques for investigating the coupling effect can lead to errors in reactivity estimates of more than the prompt critical limitation.

abstract: Doctor of Philosophy (PhD)


title: Design and Implementation of a Hybrid Multipath Simulation system for the Study of Diffuse Multipath

contributor:
Haykin, S.
Electrical Engineering

subject:
Electrical and Electronics
Electrical and Electronics

abstract:
Radiation returning from a target at low elevation to a radar can have a wide variety of characteristics. In general, we see return not only from the target itself, but from its image as well; this is the essence of multipath. The nature of this multipath depends on a number of factors, the most important of which is the roughness of the reflecting surface. The study of this return is essential in order that we may overcome the problems associated with target detection in multipath environments.

In this thesis, methods of simulating diffuse multipath are discussed, and a hybrid system has been constructed which illustrates the effect of a phased array receiver on the observed radar return.

abstract: Master of Engineering (ME)


title: Track/Train Dynamics

contributor:
Dokainish, M.A.
Mechanical Engineering

abstract:
The dynamic response of the railway track modelled as a continuously supported beam on a Kelvin type foundation and subjected to an axial force and time dependent moving loads is studied. The transient and steady state solutions are found for the general case including all linear effects. This study shows the effects of axial force and damping on the dynamic response. The results also show that the effect of the velocity of the moving load on the dynamic response is small, and hence it is not necessarily to consider the wave type expression to study the effect of track elasticity on the dynamics of railway vehicles.

An analysis for the dynamics of a railway vehicle including the effect of vertical track elasticity is presented, with particular emphasis on the lateral stability and the response to vertical track irregularities. The model used in the analysis is that of a six-axle locomotive of the type commonly used in North America. Wheel tread profile parameters, gravity stiffness effects and creep forces are included in the mathematical model.

The results show that an increase in vertical track elasticity results in a small increase in the critical speed at which hunting instability occurs. The increase in track elasticity results in appreciable increase in the amplitude of the response to track irregularities especially at high frequencies.

A method for the minimization of the vibrations transmitted due to track irregularities using the minimax principle and mathematical programming techniques is suggested. The method is demonstrated by considering the minimization of the lateral cab acceleration within the frequency range of interest.

The analyses and digital computer simulations are viewed as analytical tools for studying the effect of changing the vehicle and/or track parameters on the dynamic response of both the vehicle and the track. The methods developed are general and can be used in the design stage to adjust geometry and/or suspension characteristics for any proposed design of a railway vehicle.

abstract: Doctor of Philosophy (PhD)


title: Properties of Surface Runoff in the High Arctic

contributor:
McCann, S. B.
Geography

subject: Geography Geography

abstract:
The Mecham River is a stream near Resolute, Cornwallis I., N.W.T., which has an arctic nival regime. It flows only in summer, from June or early July to late August or early September. Discharge begins shortly after the snowpack becomes fully ripe under the influence of increasing temperature and radiation. Over a period of about two weeks it rises rapidly to a spring snowmelt peak from which there is a gradual recession through the rest of the summer. Superimposed on the recession there are (in most summers) occasional rainstorm responses. These floods are rapid to rise and to fall, because the bare terrain with shallow underlying permafrost has little capacity to detain or retain water. Diurnal fluctuations are also superimposed on the seasonal pattern of discharge; they can be related to diurnal fluctuations of incoming radiation, and although they are sometimes subdued late in the season they can be very pronounced before rainwater runoff begins to drown them out.

The most important findings of the study concern the annual water balance of the Mecham River basin. Several terms of possible importance in the water balance can be eliminated. Changes in frozen water storage and in lake storage may be neglected because the basin contains very few snowbanks and lakes. Annual changes in the moisture content of the active layer may also be neglected, although more understanding of how the active layer behaves hydrologically would be valuable for other purposes besides the solution of the water balance. The flux of windblown snow across the drainage divide has been suspected to be large, at least potentially, but an analysis of basin topography shows that this is unlikely to be so in basins as large as that of the Mecham River. The remaining terms in the water balance are snowfall, rainfall, evaporation and discharge.

Three of these are measured at Resolute or on the Mecham River itself. The fourth - evaporation - must be calculated indirectly. The method chosen in this study was an application of the combination model to the weather data collected routinely at Resolute. The hardest problem encountered in developing the model was the accurate estimation of surface wetness, although improvements would also be desirable in measurements of the wind speed profile, the soil heat flux perhaps in the estimation of basin snow cover. Nevertheless, comparisons of the results with pan evaporation measurements suggest that the model performs well. Comparisons with Priestley and Taylor's approach to the estimation of the vapour flux are also encouraging: their empirical coefficient is larger at Resolute (1.47) than elsewhere (1.26), probably because Resolute is a windy place.

An accounting of the water balance reveals gross discrepancies between inputs (precipitation) and outputs (evaporation and discharge). A small numerical allowance for unrecorded trace precipitation does not come near to removing the disparity, which is such that on average outputs exceed measured inputs by 400 percent. Most of the disparity must be attributed to underestimation of precipitation, which is thus about four times greater than has been supposed in this "arid" locality.

Measurements of sediment concentration in the Mecham River suggest that, if the amount of water in hydrologic cycle has been underestimated, so too has its effectiveness as a geomorphic agent. Having a gentle slope and a coarse-grained channel bed, the Mecham River carries little bed load, but its suspended sediment load is comparable with those measured in compared physiographic and lithologic situations at lower latitudes. The largest fraction of its sediment load is made up of dissolved Ca, Mg and HCO3. In comparison with warmer waters draining better-vegetated carbonate terrains, the Mecham waters have low solute concentrations, though the solute load is by no means negligible. Average Ca concentrations in the Mecham River and its basin are those which would be expected (allowing for an inverse relationship with discharge) in waters at equilibrium with atmospheric CO2 and near saturation with respect to calcite. Even moderate admixtures of biogenic CO2 can be shown to increase the aggressivity of these High Arctic waters towards calcite, and the notion that more limestone is dissolved at lower temperatures (sc., in cold periglacial regions) can now be considered dispelled.

abstract: Doctor of Philosophy (PhD)


title: Metal Complex Catalysed Reactions of Anils

contributor:
Eaton, D. R.
Chemistry

subject: Chemistry Chemistry

abstract:
It has been found that a series of thiourea metal complexes are very efficient catalysts for a number of reactions involving anils. These reactions, the formation and hydrolysis of the anil and a transimination reaction, were studied using acetone and various substituted anilines as substrates. The catalysts were Co(II) and Zn(II) complexes of thiourea and substituted thioureas and were found to have a wide range of effectiveness as catalysts.

Kinetic studies have been carried out using a number of NMR techniques, including measurement of initial rates by integration, line broadening studies and spin saturation transfer (SST) experiments. Equilibrium constants for association of various substrates with the catalysts have also been determined, taking advantage of the paramagnetism of the Co(II) complexes.

The results indicate that the rate determining step for the formation of the anil involves nucleophilic attack of aniline on coordinated acetone. The aniline in this case is the second coordination sphere of the metal complex and the acetone is in the first analogous mechanisms. The utility of SST experiments is demonstrated by the identification of the transimination reaction and the measurement of two exchange processes in this reaction.

abstract: Doctor of Philosophy (PhD)


title: Nuclear Volumes: An Analysis During a Cell Cycle

contributor:
Davidson, D.
Biology

subject: Biology Biology

abstract:
Cells in root meristems of Vicia faba are heterogeneous for cell cycle duration, nuclear volume and cell shape. The present study was made: (1) to determine volumes of meristem cell nuclei, (2) to analyze changes in nuclear volumes during a cell cycle in a marked population of tetraploid cells in the meristems of long lateral roots.

The results show that there is also heterogeneity in nuclear volume, growth rates of nuclei, protein content and shapes of nuclei. The degree of heterogeneity is different in meristems of roots at different developmental stages. The results also reveal that there is no definite correlation between the volume of a nucleus and its age in interphase. Furthermore, nuclei of non-cycling cells also appear to grow.

The data on the marked population of tetraploid cells provide specific information about changes in nuclear volumes during one cell cycles. The range in nuclear volumes is large even in early G1. Nuclei grow at different rates: 1) within any one subphase of interphase, 2) between different subphases. Even the volumes of prophase nuclei from cells with more or less the same cell cycle duration (i.e., fast cycling cells) appear to be variable. This indicates variability in nuclear growth rates even among the cells that take approximately the same time to complete a cell cycle.

From the volumes of metaphase chromosome complements, an estimate can be made of minimum possible volume of nuclei at the beginning of interphase. The variability of these values suggest that there is a range of volumes among the nuclei at the very beginning of interphase. Hence, one of the factors affecting nuclear growth could be the volumes and, therefore, the chemical composition of the chromosome complements from which the nuclei are formed.

abstract: Doctor of Philosophy (PhD)


title: Diffusion-Controlled Copolymerization Kinetics

contributor:
Hamielec, A.E.
Chemical Engineering

abstract: A general kinetic model which accounts for diffusion-controlled termination and propagation in free-radical copolymerization up to high conversions was developed. This model was tested on batch kinetic data for styrene/p-methyl styrene thermal copolymerization and data on the chemically-initiated bulk copolymerization of methyl methacrylate/p-methyl styrene. The model gave reasonable predictions of conversion, copolymer composition and molecular weights for these copolymer systems and thus should find use in the design, optimization and control of copolymer reactors.

abstract: Doctor of Philosophy (PhD)


title: Photochemistry of Aromatic Compounds Involving Charge Transfer

contributor:
McCullough, J.J.
Chemistry

subject: Chemistry Chemistry

abstract:
Photoreaction of naphthalene with pyrrole in various solvents has been studied. The major products are 2-(l,4-dihydro-l-naphthyl)-pyrrole and 2-(1,2-dihydro-2-naphthyl)-pyrrole which together comprise 85% of the products mixture. Solvent dependence of both products ratio and quenching of naphthalene fluorescence have also been investigated. The evidence suggests that the reaction is initiated by charge transfer from pyrrole to the lowest excited singlet naphthalene followed by a proton shift from the N-position of pyrrole to a negative charge center in the naphthalene ring. Using N-deuteriopyrrole in the reaction, it was found that deuterium is incorporated at the naphthalene ring in the products. Further evidence to support the proton shift mechanism is that N-methylpyrrole quenches naphthalene fluorescence as efficiently as pyrrole, but the reaction does not take place.

The photoreaction of l-cyanonaphthalene with tetramethylethylene in methanol and benzene have been studied. Substitution products were found in methanol solution but a cyclo-adduct was formed in benzene. Tetramethylethylene quenches fluorescence of l-cyanonaphthalene both in methanol and benzene.

In contrast, 2-cyanonaphthalene only reacts with tetramethylethylene in methanol to give substitution products with one mole of methanol incorporated. The failure of reaction in benzene is consistent with the absence of fluorescence quenching in that solvent; in methanol, quenching occurs at the diffusion controlled limit.

abstract: Doctor of Philosophy (PhD)


title: Body Temperature Regulation during Heat Stress in the Pregnant Rat

contributor:
Stricker, E. M.
Psychology

subject: Psychology Psychology

abstract:
Body temperature regulation at high ambient temperatures was compared in pregnant and non-pregnant female albino rats. At an ambient temperature of 40ºC, pregnant rats maintained lower body temperatures than non-pregnant rats without added expenditure of moisture for evaporative cooling. This was surprising because of the increased heat load on the pregnant animal resulting from a large weight gain and increased food intake. The maintenance of lower body temperatures in the heat by pregnant rats was possible because (1) pregnant rats produce less heat; i.e. consume less oxygen during exposure to 40ºC than do non-pregnant rats and thus need to dissipate less heat; and (2) pregnant rats have a lower body temperature threshold for increased submaxillary salivary gland output in the heat, which makes more water for evaporative cooling available to them at lower body temperatures.

The maintenance of lower body temperatures in the heat by pregnant rats suggests that pregnant rats have a need or a preference for lower body temperatures in the heat. The change in body temperature regulation during pregnancy is likely related to physiological and anatomical changes in the body which accompany pregnancy. Alterations in body temperature regulation to meet the changed physiological state of pregnancy provide another example of the body's remarkable ability to maintain homeostasis.

abstract: Doctor of Philosophy (PhD)


title: Bounded Pseudo-Complete Locally Convex *-Algebras

contributor:
Husain, T.
Mathematics

subject: Mathematics Mathematics

abstract: We introduce a new class of locally convex algebras called BP*-algebras. They form a considerably larger class than that of MQ*-algebras which were introduced and studied by T. Husain and Rigelhoff. We discuss continuity of positive linear functionals on these algebras. We characterize extreme points of normalized positive functionals and obtain several results on representations of these algebras.

abstract: Doctor of Philosophy (PhD)


title: An Analysis of a Fast Carrier Recovery System for TDMA

contributor:
Taylor, D. P.
Electrical Engineering

abstract: Phase-locked loops occasionally exhibit prolonged phase transients and are therefore not suitable for carrier recovery applications in time division multiple access (TDMA) systems. Instead, designers have, in several cases, used a single-tuned high Q filter in combination with an automatic frequency control. A non-linear differential equation model for such a system, called a "frequency locked loop" (FLL) is solved by computer to obtain the transient responses. The solutions obtained indicate that the FLL has fast and reliable carrier phase acquisition time compared to a phase-locked loop (PLL). Also, since the non-linear responses agree well with linear model responses, an equation based on the linear model is developed to determine worst-case acquisition time. It is shown that a limiter preceeding the single-tuned tank does not directly affect acquisition performance and will improve noise performance of the FLL. With a limiter, the FLL block diagram is equivalent to an FM feedback demodulator (FMFB) on which there is a large amount of existing literature. Using results from the literature, it is demonstrated how the FMFB will perform in the presence of Gaussian noise. Finally, a design procedure is recommended which takes into account the tradeoff between noise performance and acquisition/tracking ability and attempts to minimize the acquisition time for a given level of Gaussian noise.

abstract: Master of Engineering (ME)


title: The Spectra of the Diethynylbenzenes

contributor:
King, G. W.
Chemistry

subject: Chemistry Chemistry

abstract:
The vibrational spectra of the three isomeric diethynylbenzenes (ortho, meta and para) are analyzed and the fundamental frequencies are assigned.

Three electronic absorption systems are observed for each diethynylbenzene. The observed positions and intensities of these three transitions agree closely with the results of CNDO calculations. The transitions show large red shift with respect to the analogous absorptions in benzene.

Rotational band contour analysis confirms the occurrence of two types of bands, single and double headed, in the lowest-energy transition of the diethynylbenzenes.

It is argued that, at present, nothing definitive can be said about the geometry of the aromatic ring in the ground and first excited electronic state of derivatives of benzene.

abstract: Doctor of Philosophy (PhD)


title: Lipid and Carbohydrate Metabolism in Muscle of Rainbow Trout (Oncorhynchus Mykiss) During Exercise and Recovery

contributor:
Wood, Chris M.
Biology

subject: Biology Biology

abstract:
A biochemical approach was employed to examine the oxidative utilization of lipid and carbohydrate in red and white muscle of rainbow trout (Oncorhynchus mykiss) during high- and low- intensity exercise and during recovery from high-intensity exercise. Measurements of the activation state of the rate-limiting enzymes, glycogen phosphorylase (Phos) and pyruvate dehydrogenase (PDH), and their allosteric regulation of pathways involved in lipid and carbohydrate oxidation in fish muscle.

High-intensity exercise in trout is powered predominately by white muscle. During the first 10 s of exercise, high ATP turnover rates (3.7 μmol·g-1 wet tissue·s-1) are achieved by rapid creatine phosphate (CrP) hydrolysis and glycolysis. Activation of glycolysis is achieved by a large transformation of Phos into its active form. Exercise performed from 10 s to exhaustion (52 s) occurs at a lower ATP turnover rate (0.5 to 1.2 μmol·g-1 wet tissue·s-1) and is primarily supported by glycosis. A gradual transformation of PDH into its active form points to a minor contribution of oxidative phosphorylation of carbohydrate to support ATP turnover. The gradual activation of PDH and an increasing mitchondria redox ([NAD+]/[NAHD]) in white muscle during exercise suggests that O2 is not limiting during high-intensity exercise and thus anaerobiosis may not be responsible for lactate production in trout white muscle.

During recovery from high-intensity exercise, there is a rapid activation of pathways involved in lipid oxidation to provide ATP for CrP, ATP, and glycogen synthesis. A rapid transformation of PDH into its inactive form spares lactate from an oxidative fate, likely to serve as the substrate for in situ glycogen re-synthesis. Decreases in free carnitine and increases in long-chain fatty acyl (LCFA) carnitine, acetyl-CoA, and acetyl canitine indicate an activation of pathways involved in lipid oxidation. Increases in white muscle malonyl-CoA during recovery suggest that malonyl-CoA may not regulate carnitine palimtoyltransferase-1 in trout white muscle.

Sustainable, "aerobic" exercise at 30 and 60% Ucrit is characterized by an inital (2 min) oxidative utilization of carbohydrate for ATP production. Withink 15 min swimming at 30 and 60% Ucrit, PDH activation returns to resting values, and at 240 min increases in LCFA-carnitine and decreases in malonyl-CoA indicate an overall enhancement of lipid oxidation. Non-sustainable swimming at 90% Ucrit is characterized by a sustained activation of red muscle PDH. Overall, sustained swimming at 30 and 60% Ucrit is supported by approximately equal contributions of carbohydrate (~45%) and lipid (~35%) oxidation, whereas non-sustainable swimming is supported primarily by carbohydrate oxidation.

Palmitate uptake by red and white muscle membrane vesicles is facilitated by a saturable transport mechanism which is sensitive to phloretin, 4,4'diisothiocyanatostilbene-2,2'-disulfonic acid, (DIDS), and mercury. Red and white muscle transporters have similar affinities for palmitate (Km=26±6 and 33±8 nM free palmitate, respectively), but red muscle exhibits a significantly higher maximal uptake rate compared to white muscle (Vmax = 476±41 and 227±23 pmol·mg-1 protein·s-1, respectively). Prolonged swimming and chronic cortisol elevatins do not stimulate palmitate uptake by muscle, indicating that the mechanisms involved in LCFA uptake by muscle cells may not limit lipid oxidation in trout muscle.

abstract: Doctor of Philosophy (PhD)


title: Trace Analysis for Mercury in Biological Material

contributor:
Fritze, K.
Chemistry

subject: Chemistry Chemistry

abstract: The need for accurate trace analysis for mercury due to its very toxic nature and widespread distribution is discussed. Critical investigations of the two currently most widely used analytical techniques, neutron activation analysis and cold vapour atomic absorption, are reported in detail. Many problems with the methods of analysis for mercury are delineated, and improvement are outlined. Procedures for obtaining best results are recommended. An instrumental improvement involving a photon-counting readout for the atomic absorption method is reported. A comparison of the analytical techniques is given.

abstract: Doctor of Philosophy (PhD)


title: Double Positron-electron Pair Production, an Interaction of Electromagnetic Radiation with Matter

contributor:
Kennett, T. J.
Physics

subject: Physics Physics

abstract: The task of detection and measurement of the instantaneous process of double positron-electron pair production was undertaken. Several targets of different atomic number were used, in conjunction with 6.6-MeV gamma rays, to isolate the process from the interfering two-pair processes known as the bremsstrahlung-cascade and the direct-cascade effects. A quantitatively significant value has been determined for the cross section for double pair production relative to that for single pair production.

abstract: Doctor of Philosophy (PhD)


title: Industrial Structure and Urban Growth of Canadian Cities 1951-1961

contributor:
King, L. J.
Geography

subject: Geography Geography

abstract:
This dissertation proposes that employment in cities can be classified into one of three categories - national, regional and local industries. A method of classifying industries into these groups is developed. However, a clear discrimination between classes is difficult to achieve. There is overlap between national and regional and regional and local industries.

These groups of industries are then analysed separately. There general relationships are identified: for a majority of cities, employment change in national industries is related to city infrastructure and metropolitan status; regional industry employment change is related to a city's location in relation to larger cities, the population of its trade area and its role in a regional hierarchy; finally local industry employment change is associated with a city's metropolitan influence and its total income. However in all three industry groups particular cities have employment changes not commensurate with these general relationships.

Furthermore, analysis of employment change in subgroups of industries shows change in employment in individual industries does not correspond to the general relationship identified for the aggregate of which it is a part.

It is clear that the general relationships found for each employment group do not necessarily apply to individual cities nor to individual industries. Analysis of growth in one city or one industry requires a different strategy to the adopted here.

abstract: Doctor of Philosophy (PhD)


title: Methods Variability for Magnesium Determination in a Biological Standard and Other Biological Materials

contributor:
Fritze, Klaus
Chemistry

subject: Chemistry Chemistry

abstract:
The use and analysis of biological standard reference materials has increased rapidly over the past few years with the mounting concern over the environment and the upsurge in health-related chemistry. Laboratory and method intercomparisons are an essential part of any program involved in the issuance of calibration of instrumental systems. It relies on the precision and accuracy of such analyses, often for vital decisions affecting public welfare. The lack of agreement among qualified analysts can thus be viewed with some dismay.

An attempt was made to examine in some detail the determination of magnesium in several biological materials using fundamentally different methods of analysis. Three procedures, a gravimetric precipitation with oxine, atomic absorption analysis and neutron activation, the latter both non-destructive and with chemical separation, were selected for the analysis in a biological standard (Bowen's kale). The latter two methods were then applied to a homogenized rat carcass and a feces sample.

Procedures were developed which gave reproducible results for the gravimetric and atomic absorption analysis. Discrepancies in the analysis by atomic absorption with and without standard addition were studied. Neutron activation gave results which were in good agreement with the other methods provided that care was taken to account for flux variations within the pneumatic rabbit. A best value of 1663 ± 7, ppm was ascertained for the magnesium content of the dried kale.

Analyses of the rat samples by atomic absorption and neutron activation were also in close agreement, thereby helping to establish the overall accuracy of the procedures. For these samples, best values of 1550 ppm and 7370 ppm were obtained for the carcass and feces, respectively. An existing method discrepancy was resolved.

abstract: Doctor of Philosophy (PhD)