title: Advances in Space Mapping Technology Exploiting Implicit Space Mapping and Output Space Mapping

contributor:
Bandler, John W.
Electrical and Computer Engineering

subject:
Electrical and Computer Engineering
Electrical and Computer Engineering

abstract: This thesis contributes to advances in Space Mapping (SM) technology in computer-aided modeling, design and optimization of engineering components and devices. Our developments in modeling and optimization of microwave circuits include the SM framework and SM-based surrogate modeling; implicit SM optimization exploiting preassigned parameters; implicit, frequency and output SM surrogate modeling and design; an SM design framework and implementation techniques. We review the state of the art in space mapping and the SM-based surrogate (modeling) concept and applications. In the review, we recall proposed SM-based optimization approaches including the original algorithm, the Broydenbased aggressive SM algorithm, various trust region approaches, neural space mapping and implicit space mapping. Parameter extraction (PE) is developed as an essential SM subproblem. Different approaches to enhance uniqueness of PE are reviewed. Novel physical illustrations are presented, including the cheesecutting problem. A framework of space mapping steps is extracted. Implicit Space Mapping (ISM) optimization exploits preassigned parameters. We introduce ISM and show how it relates to the now well established (explicit) space mapping between coarse and fine device models. Through comparison a general space- mapping concept is proposed. A simple ISM algorithm is implemented. It is illustrated on the contrived "cheese-cutting problem" and applied to EM-based microwave modeling and design. An auxiliary set of parameters (selected preassigned parameters) is extracted to match the coarse model with the fine model. The calibrated coarse model (the surrogate) is then (re)optimized to predict an improved fine model solution. This is an easy SM technique to implement since the mapping itself is embedded in the calibrated coarse model and updated automatically in the procedure of parameter extraction. We discuss the enhancement of the ISM by "output space" mapping (OSM) specifically, response residual space mapping (RRSM), when the model cannot be aligned. ISM calibrates a suitable coarse (surrogate) model against a fine model (full-wave EM simulation) by relaxing certain coarse model preassigned parameters. Based on an explanation of residual response misalignment, our new approach further fine-tunes the surrogate by the RRSM. We present an RRSM approach. A novel, simple "multiple cheese-cutting" problem illustrates the technique. The approach is implemented entirely in the Agilent ADS design environment. A new design framework which implements various SM techniques is presented. We demonstrate the steps, for microwave devices, within the ADS (2003) schematic design framework. The design steps are friendly. The framework runs with Agilent Momentum, HFSS and Sonnet em. Finally, we review various engineering applications and implementations of the SM technique.

abstract: Doctor of Philosophy (PhD)


title: In Vivo Structure-Function Studies of the ErbB2 Receptor Tyrosine Kinase

contributor:
Muller, William J.
Biology

subject: Biology Biology

abstract: The ErbB2 receptor tyrosine kinase plays important roles in both mammalian development and in oncogenesis. Signal transduction mediated by the receptor is dependent on the catalytic activity of its tyrosine kinase domain and the phosphorylation of discrete tyrosine residues within the receptor. To perform structure-function studies in vivo and to evaluate the function of tyrosine phosphorylation, an allelic series of erbB2 cDNA knock-in animals were generated such that the erbB2 cDNA was under the transcriptional control of the endogenous promoter. Mice homozygous for the kinasedead erbB2 allele died at midgestation and displayed the same spectrum of embryonic defects observed in erbB2 deficient animals. In contrast, expression of ErbB2 receptors harboring a single tyrosine site mutation in the carboxy-terminus of the receptor resulted in viable animals. However, expression of ErbB2 receptors de-coupled from the Shc signaling pathway (Y 1226/7F) lead to subtle defects in the development of cutaneous sensory nerves. The cDNA knock-in alleles were inadvertently hypomorphic expressing a minimum threshold level of ErbB2 (~1 0% of wild type) required for survival. Indeed, a further 2-fold reduction in ErbB2 levels in hemizygous knock-in animals resulted in perinatal lethality due to defective innervation of the diaphragm leading to acute respiratory distress. Interestingly, this hypomorphic phenotype was genetically rescued when the ErbB2-Y1028F mutant receptor was expressed in animals using a comparable knock-in strategy. Subsequent molecular analyses revealed that the YI028F allele expressed higher levels of ErbB2, due to the decreased turnover rate of the receptor following removal ofY1028. This downregulation was independent of c-Cbl association and ubiquitylation of the receptor. Instead, ErbB2-Yl144 and Y122617 can associate with c-Cbl but the receptor remains refractory to c-Cbl mediated ubiquitylation. Additionally, ErbB2 is monoubiquitylated through an unidentified mechanism mediated by the Y1253 phosphorylation site. Taken together, these results provide important novel insight into the function and regulation of the ErbB2 receptor.

abstract: Doctor of Philosophy (PhD)


title: An Experimental Investigation on the Free Radical Synthesis and Characterization of Styrene Acrylonitrile Copolymers

contributor:
Hamielec, A.E.
McGregor, J.F.
Chemical Engineering

subject:
Chemical Engineering
Chemical Engineering

abstract:
This Thesis report on the free radical synthesis and characterization of styrene/acrylonitrile (SAN) copolymers.

A wide region of the kinetic behaviour of SAN copolymers has been experimentally mapped. The effects of temperature, initiator and comonomer concentrations on the rate of reaction and copolymer properties were experimentally investigated and discussed in view of the existing theory. Using low conversion copolymers as standards, current copolymer characterization techniques with particular emphasis on size exclusion chromatography (SEC) have been investigated. Polymer/solvent/packing interactions, instrumentation, calibration and interpretation techniques for SEC were investigated and extended to copolymer analysis.

This investigation, as part of an ongoing program on the synthesis characterization, modelling and control of copolymers and copolymerization reactions, provides some of the systematic ground work essential to the understanding and eventual modelling of these rather complex systems.

abstract: Doctor of Philosophy (PhD)


title: 4.3-μm CO₂ Laser

contributor:
Garside, B.K.
Ballik, E.A.
Physics

subject: Physics Physics

abstract:
The work described in this thesis concerns the investigation of the properties of a new type of CO₂ laser, one which operates in the wavelength region near 4.3 μm rather than in the 9-11-μm region where most CO₂ lasers operate. Lasing at 4.3 μm is achieved by using a 10-μm sequence CO₂ laser to optically pump CO₂ molecules which have been excited in an electrical discharge. The laser is based on existing CO₂ laser technology, and therefore it is potentially a very useful source of coherent radiation in a spectral region where there are presently few lasers suitable for widespread use.

Preliminary experiments are described which serve to identify the various physical processes involved in 4.3-μm Iaser action. Efficient optical pumping is demonstrated and peak output powers of 1 kW are observed. A theoretical model of the laser is developed. The model can accurately predict the observed 4.3-μm output and it is shown that the lifetime of the upper laser level is the critical factor in determining the gain dynamics of the laser system.

Two principal operating regimes are identified. The first is a high repetition rate Q-switched mode suitable for the production of high average power. A Q-switched 4.3-μm laser is constructed, employing continuous discharge tubes and SF₆ is used to passively Q-switch the sequence oscillator. The average output power at 4.3 μm is 120 mW.

The other operating regime is a high power pulsed mode. This involves scaling the laser to higher operating pressures, which requires the use of high levels of sequence pumping power. To this end, a TEA sequence CO₂ laser having output energies of up to 6 J per pulse was developed, and design criteria for such lasers are presented. The scalability of the 4.3-μm laser, using the TEA sequence laser as the pump source, is discussed. The factors which limit the maximum output power attainable are identified, and guidelines for the construction of high power 4.3-μm lasers are presented.

abstract: Doctor of Philosophy (PhD)


title: Analysis of Highflows in the Fraser River Catchment, British Columbia

contributor:
Woo, M.K.
Geography

subject: Geography Geography

abstract:
Frequency characteristics of highflows in the Fraser River catchment, British Columbia, are modelled in such a way as to permit their prediction for ungauged basins.

Two definitions of highflows, annual flood and partial duration series, are examined. The two series are shown to be stationary and serially independent. The Gumbel distribution is found to describe adequately the observed annual flood data. Following theoretical considerations a nonhomogenous Poisson distribution is used to model the time-dependent behaviour of the number and timing of highflows derived from the partial duration series. Their magnitudes and periods of duration are found to be exponentially distributed.

The 2 year return period annual flood provides the truncation level for the regional analysis. A method of predicting partial series at other levels of interest from this base is proposed and tested. The relationship between the two highflow series is presented and a theoretical distribution for the estimation of annual flood frequencies from partial series is tested across the study area. It compares favourably with the Gumbel distribution as a means of representing the observed annual flood data.

The estimated parameters of the probability distributions employed are entered into a regionalisation procedure that permits the definition of highflow groups. Within each of the derived groups the parametric values are related to basin physiographic and climatic variables by means of multiple regression equations. The groups are found to be defined by simple, meaningful physical variables which allow the extension of the groups to provide a regional demarcation of the study area. The regression equations are applied to test basins within the Fraser catchment and the results indicate that the method is suitable for the estimation of highflow characteristics in ungauged basins.

abstract: Doctor of Philosophy (PhD)


title: Gap Junction Formation in Uterine Smooth Muscle at Parturition

contributor:
Daniel, Edwin E.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
The development of synchrony is characteristic of uterine muscle at the end of pregnancy. The coordinated contractile activity of the smooth muscle is effective in delivering the fetuses. A structural change occurs late in gestation, and specialized sites of intercellular communication, gap junctions, appear between the uterine smooth muscle cells. The objectives of this thesis were to characterize the time course of gap junction formation, investigate some factors that govern their appearance, and examine the possible significance of gap junction formation in the myometrium. Electrophysiological methods were used to evaluate the hypothesis that gap junction formation at parturition resulted in improved electrical communication between cells. Improved coupling might allow the synchronization of uterine activity.

Gap junctions were shown by quantitative thin section electron microscopy to be present between uterine smooth muscle cells immediately prior to, during, and for a short time following parturition in the rat. Several experiments involving ovariectomy revealed that the stimulus for gap junction formation was systemic in nature. Bilateral ovariectomy of midterm pregnant rats resulted in premature termination of pregnancy and gap junction formation, both of which were blocked by hormone administration. These and other results suggest that progesterone withdrawal may regulate gap junction formation in rat myometrium, but many factors, such as estrogen and prostaglandins, may also be involved.

Uterine smooth muscle is a functional electrical syncytium, and properties of electric current flow through the muscle yield indirect estimates of cell-to-cell coupling between cells. Impedance analysis showed that the specific resistance of the cytoplasm of myometrial cells was constant from before term to delivery, but the junctional resistance decreased. Shortly post partum the junctional resistance increased. Cable analysis confirmed that the internal resistance of myometrium was lower at parturition. Thus, improved cell-to-cell communication was associated with a demonstrated increase in gap junction contact between cells. These results are consistent with the hypothesis that gap junction formation at the end of gestation results in improved electrical coupling of uterine smooth muscle cells.

abstract: Doctor of Philosophy (PhD)


title: Alpha-l-Protease Inhibitor, an Acute Phase Reactant in Inflammation

contributor:
Gauldie, Jack
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
Alpha-l-protease inhibitor (αlPi) is a plasma glycoprotein which plays a major role in limiting proteolysis during inflammation due to its broad spectrum of inhibitory activity.

The purification and partial characterization of αlPi have allowed for its investigation as an acute phase reactant during inflammation.

Mouse αlPi is a glycoprotein of molecular weight 53,500 with a half-life of approximately 15.5 hours. On two dimensional immunoelectrophoresis, two variants of αlPi were seen which exhibited immunological non-identity. The two variants showed trypsin binding activity, both were synthesized by hepatocytes, and both behaved as acute phase reactants.

The ubiquitous nature of alPi was evident from its presence in a wide variety of body fluids. Using an immunohistochemical stain, the inhibitor was shown to be normally present in the cytoplasm of hepatocytes, islet cells of pancreas and in some villous epithelial cells of the small intestine. The hepatocyte was shown to be the major source of serum αlPi. Alveolar macrophages, shown to contain αlPi histochemically in particular inflammatory states of the lung, synthesized minimal quantities.

The acute phase response of αlPi was investigated in four models of inflammation consisting of either a subcutaneous injection of celite or infection with one of three parasites: Nippostrongylus brasiliensis; Trichinella spiralis; and Trypanosoma congolense. In addition, studies have been initiated with other mouse acute phase reactants, namely, complement component C3, serum amyloid P (SAP) and serum amyloid A (SAA).

The induction of acute phase protein synthesis during inflammation was characterized by an increase in the number of hepatocytes staining for αlPi. During inflammation the level of hepatocyte staining was shown to correlate with the synthetic output of αlPi. The maximum staining activity for αlPi in hepatocytes preceded the peak increase in serum levels during inflammation. Moreover, there was a characteristic, progressive alteration in the distribution pattern of stained hepatocytes within the liver lobule. These results were consistent with an acute phase mediator perhaps originating from the site of inflammation, gaining access to the liver via the portal circulation causing an induction of acute phase protein synthesis.

The synthesis of an acute phase mediator (APM), probably interleukin 1 (ILl), by alveolar macrophages and the in vitro induction by APM of αlPi synthesis by hepatocytes has been demonstrated.

It was also shown that αlPi accumulated at the site of inflammation which may account for the apparent lack of increase in serum levels even though there was an increased hepatic output of alPi at that time.

Collectively these results demonstrate that in the mouse the induction of synthesis of αlPi during an acute response to inflammation is mediated by an acute phase mediator originating from macrophages at the site of inflammation.

The increased synthesis of αlPi has been shown in pivo by a measure of serum levels and immunohistochemical examination of liver tissue as well as in vitro by cultures of isolated hepatocytes.

These studies constitute a basic framework upon which mechanisms for the induction and control of synthesis of acute phase proteins can be further explored.

abstract: Doctor of Philosophy (PhD)


title: Response Bursts on DRL Schedules

contributor:
Platt, J. R.
Psychology

subject: Psychology Psychology

abstract:
The differential reinforcement of low rates schedule typically yields from the subject a distribution of interresponse times (IRTs) that is bimodal. One mode occurs at or near the reinforced value and a second one at IRT values less than 2.0 sec. The IRTs which comprise this latter mode have been termed "response bursts" (Sidman, 1956). Various explanations for the mode at short values have been offered: Blough (1963, 1966), arguing from pigeon data only, suggested that these short IRTs are due to variation in the topography of the pigeon's keypeck response, the double-peck being a variation of the peck. Kramer & Rilling (1970) noted that if the definition of what actually constitutes a response is not clear to the subject, then quick multiple responses might result. Finally, Sidman (1956) has viewed these sequences of rapidly-made responses as evidence of increased response strength at certain times.

A comparison of IRT distributions from mice, rats, and pigeons, however, shows such similarities in the patterning of bursts that Blough's suggestion of topographic variation in the pigeon's key peck cannot be a satisfactory explanation for the occurrence of these short IRTs. To test Kramer and Rilling's suggestion that lack of clear response definition may produce multiple responses, mice were trained on a DRL 18 sec schedule and given response feedback in the form of an auditory stimulus. The results of a series of such experiments indicated that while a relatively long-duration auditory stimulus (2.0 sec) would almost eliminate bursting, it did this by acting as an S Δ rather than as response feedback per se. The fact that a short-duration (0.2 sec) auditory stimulus did not suppress bursting showed that bursting was not the result of lack of response definition. Further analysis of the patterning of response bursts lent substance to Sidman's contention that response bursts are a reflection of momentary increase in response strength. Specifically, bursts were found to occur most often as time to reinforcement availability decreased; bursts never occurred immediately after responses which were reinforced (i.e., when time to reinforcement availability was greatest); and the length of a burst run (number of responses) was greater the closer it occurred to the time of reinforcement availability. It was concluded that Sidman's interpretation of the DRL schedule as a temporal discrimination task is consistent with the response burst data from the experiments described here.

abstract: Master of Arts (MA)


title: Analysis of Virus-Induced Cell-Mediated Immune Responses in Susceptible and Resistant Strains of Inbred Hamsters

contributor:
Rawls, William E.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
The arenaviridae are a group of enveloped, negative-stranded RNA viruses. These viruses characteristically produce persistent infections in their natural host, which is how they are maintained in nature. Experimentally-induced arenavirus disease has been found to possess similar pathological features of human disease. In the inbred MHA strain of Syrian hamster, Pichinde virus causes a fatal infection when inoculated intraperitoneally. Investigation of the factors leading to a fatal Pichinde virus disease in Syrian hamsters revealed that susceptibility was genetically determined. Susceptibility of MHA hamsters to a lethal infection of the virus appeared to be related to the presence of a splenic target cell for Pichinde virus replication that was minimally expressed in resistant hamster strains. In addition, during studies on cell-mediated immune responses to Pichinde virus antigens, it was discovered that MHA hamsters survived infection when the virus was given in the footpad. However, unlike the resistant LSH and LVG strain hamsters, the MHA hamsters did not manifest a footpad swelling response.

The present studies were initiated to determine some characteristics and possible mechanism(s) underlying the lack of footpad swelling response to a primary inoculation of Pichinde virus in the MHA strain hamster. MHA unresponsiveness was not due to a lack of immune recognition of Pichinde virus antigens, since this strain was shown to produce complement-fixing antibodies to Pichinde virus. Furthermore, footpad-inoculated MHA hamsters were protected against a subsequent intraperitoneal challenge with Pichinde virus.

Experiments designed to elucidate the genetic basis for presence or absence of footpad swelling revealed that expression of footpad swelling to Pichinde virus was a dominant trait controlled by a single gene or closely linked genes. Furthermore, the lack of responsiveness in MHA hamsters appeared to be specific for Pichinde virus, since footpad swelling could be elicited in this strain by footpad injection of either vaccinia virus or vesicular stomatitis virus. Histological analysis of the virus-injected footpad showed that footpad swelling was associated with an influx of mononuclear cells at the site of injection. These observations suggested that MHA unresponsiveness could not have been caused by a general defect in effector mechanisms that mediate the footpad swelling response.

A search for Pichinde virus-induced suppressor activity was then undertaken. Treatment of MHA hamsters with cyclophosphamide, a drug known to augment delayed hypersenstivity responses by inhibiting suppressor cell activity resulted in a significant footpad swelling response following Pichinde virus injection. Furthermore, transfer of lymphoid cells but not serum from 5 day footpad-inoculated MHA hamsters could specifically suppress footpad swelling to Pichinde virus in the LSH recipient.

Aqother parameter of cell-mediated immunity studied was the generation of cytotoxic cells. Pichinde virus primed MHA and LSH hamsters were capable of generating cytotoxic cells, after restimulation in vitro with virus but the cytotoxicity lacked specificity. When spleen cells from 7 day footpad-inoculated MHA hamsters were added to spleen cells from LSH hamsters, the cytotoxic activity of the latter cells was significantly suppressed.

These results taken together suggested that the absence of footpad swelling in the MHA strain hamster was caused by the generation of a cell-associated suppressor mechanism that appeared to be induced specifically by Pichinde virus.

abstract: Doctor of Philosophy (PhD)


title: ELECTROPHYSIOLOGICAL PROPERTIES, POz- AND ATP-SENSITIVITY OF PARAGANGLION NEURONS OF THE RAT GLOSSOPHARYNGEAL NERVE

contributor:
Nurse, Colin A.
Biology

subject: Biology Biology

abstract: Paraganglion neurons within the rat glossopharyngeal nerve (GPN) are part of a nitric oxide synthase (nNOS)-synthesizing plexus of nerve fibers that innervate a chemosensory organ, the carotid body (CB). This thesis focused on the anatomical, biophysical, pharmacological, and immunocytochemical characterization of these GPN neurons with a view towards understanding their role in efferent CB inhibition. GPN neurons were grouped in two distinct populations, a proximal one near the bifurcation with the carotid sinus nerve, and a more distal one concentrated further along the GPN. Both neuronal populations shared similar passive membrane properties and expressed voltage-dependent Na+, K+, and a broad spectrum ofCa2+ channels which included L-, N, P/Q-, R- and T- types. In addition, they expressed a novel 02-sensitive K+ conductance, mediated via voltage-independent background or 'leak' K+ channels. Hypoxia depolarized and/or increased excitability in GPN neurons via inhibition of these 'leak' K+ channels, whose pharmacology suggested involvement of the tandem pore domain, halothane inhibited K+ (THIK) channel family. Indeed, when THIK-l channels were heterologously expressed in HEK 293 cells, the resulting K+ currents were found to be reversibly inhibited by hypoxia. GPN neurons were also sensitive to several neurotransmitters including acetylcholine, dopamine, serotonin and importantly, ATP, acting via multiple ionotropic P2X receptors. Pharmacological and confocal immunofluorescence studies suggested that these P2X receptors consisted of at least heteromeric P2X2-P2X3, homomeric P2X4 and homomeric P2X7 receptors. In cocultures of GPN neurons and CB chemoreceptor (type I) cell clusters, activation of P2X receptors on adjacent GPN neurons caused NO-dependent hyperpolarization of type I cells. Taken together these findings suggest key roles for hypoxia and ATP in the activation of GPN neurons, leading to Ca2 + entry, NOS activation, and NO-mediated inhibition of carotid body function.

abstract: Doctor of Philosophy (PhD)


title: BROADLY TUNABLE ULTRASHORT PULSE GENERATION WITH MODE-LOCKED SEMICONDUCTOR LASERS

contributor:
Haugen, H. K.
Mascher, P.
Engineering Physics

subject:
Engineering Physics
Engineering Physics

abstract: Wavelength tunable ultrashort pulses are generated with mode-locked InGaAs/GaAs semiconductor lasers mounted in an external cavity. A broad tuning range is achieved through the use of an asymmetric quantum well (AQW) structure in the active region of the devices. Furthermore, the incorporation of a bend in the waveguide of the devices results in a broadband, low modal reflectivity. This allows the lasers to be mode-locked in a compact, linear external cavity. Passive mode-locking of dual asymmetric quantum wen deviceshave produced pulses 2 to 5 ps in duration, tunable from 954 nm to 1015 nm. Compression of the pulses using a modified grating pair compressor has yielded optical pulses as short as 510 fs. Similar devices based on a triple asymmetric quantum well active region are capable of producing pulses 2 to 11 ps in duration under passive mode-locking, tunable from 942 nm to 1017 nm. Preliminary work with long wavelength InGaAs/GaAs lasers has resulted in pulses 2 to 5 ps in duration with average output powers ranging from 750 /-lW to 1.8 mW. Pulse compression yields pulses as short as 570 fs. The synchronization of a passively mode-locked semiconductor laser to a mode-locked Ti:Sapphire laser, using an all-optical synchronization method, is studied. The parameter space is explored in order to determine the operating conditions that yield optimal synchronization of the two lasers. Good qualitative agreement is obtained between a simple theoretical model of the synchronization process and the corresponding experimental measurements. It is also shown that the synchronization of the mode-locked semiconductor laser with a femtosecond laser provides an additional means by which the mode-locked semiconductor laser can be characterized.

abstract: Doctor of Philosophy (PhD)


title: ABLATION AND MICROMACHINING OF INP WITH FEMTOSECOND LASER PULSES

contributor:
Haugen, Harold K.
Engineering Physics

subject:
Engineering Physics
Engineering Physics

abstract: This thesis details the results of femtosecond laser ablation and micromachining of indium phosphide (InP). The experimental results presented consist of six sets of investigations divided into two categories: I) single and multiple pulse ablation of stationary samples; 2) laser micromachining and analysis of grooves cut in InP. The first series of experiments dealt with the analysis of the final state of InP after single and multiple pulse irradiation. The experiments were perfonned with femtosecond pulses, 60 -175 fs in duration, centered around wavelengths of 400, 800, 660, 800, 1300 and 2100 nm. In the first set of investigations, single pulse laser ablation craters on InP and GaAs were studied via scanning and plan-view transmission electron microscopy. The final state of the material near the laser-ablated region following femtosecond ablation was characterized in detail for three selected laser fluences. In the second set of investigations, single pulse ablation threshold measurements were performed in the wavelength range from 400 - 2100 nm, covering the photon energy above and below the bandgap of InP. The ablation thresholds detennined from depth and volume measurements varied from 87 mJ/cm2 at 400 nm to 250 mJ/cm2 at 2050 nm. The measurements were performed with optical microscopy, atomic force and scanning electron microscopy. In addition, sharp onsets of the measured depths versus laser fluence were observed at the ablation thresholds. In the third set of investigations, laser induced periodic surface stnlctures were investigated on the surfaces of InP, GaP, GaAs, InAs, Si, Ge and sapphire after multiple pulse femtosecond laser irradiation in the wavelength range from 800 - 2100 nm. High spatial frequency periodic stnlctures were observed on surfaces of InP, GaP, GaAs and sapphire. The periods of the structures were 4.2 - 5.1 times smaller than the free space wavelength of the incident radiation. Conditions required for formation of these ripple stnlctures were identified. The second series of experiments dealt with the analysis of the final state of the material after the cutting of grooves in InP under conditions potentially encountered in practical applications. The experiments can be grouped into three sets of investigations. In the fourth set of investigations, the ablation rate for grooves micromachined with ~ 150 fs pulses centered around 800 nm was investigated as a function of pulse energy, feed rate, number of passes over the same groove, and the light polarization relative to the cutting direction. A logarithmic dependence of the groove depth on the laser Iluence was observed with two regimes characterized by different ablation rates and different thresholds. The groove depth was found to be inversely proportional to the feed rate or equivalently, linearly proportional to the effective number of pulses delivered. With multiple passes over the same groove the depth was found to increase linearly up to approximately 20 consecutive passes. Above 20 passes the ablation rate decreased until a depth limit was asymptotically approached. The best results in terms of groove geometry and depth limit were obtained for grooves cut with the polarization of the beam perpendicular to the cutting direction. In the fifth set of investigations, the residual strain fields resulting from laser micromachining of grooves in InP with femtosecond and nanosecond pulses centered around 800 nm were analyzed using a spatially resolved degree-of-polarization photoluminescence technique. Significant differences in the geometry of the strain patterns were observed in grooves machined in the two temporal domains. The experimental data were compared with results from a finite element model. In the sixth set of investigations, grooves micromachined in InP with femtosecond and nanosecond pulses were investigated by cross- ectional transmission electron microscopy. Substantial densities of defects, extending over a few microns in depth, were observed beneath the grooves machined with femtosecond pulses. The high peak power density and the stress confinement caused by irradiation with femtosecond pulses, along with incubation effects, were identified as the major factors leading to the observed plastic deformations.

abstract: Doctor of Philosophy (PhD)


title: 'OLDER' WORKERS: THE NEGOTIATION OF AGE DISCRIMINATION AND IDENTITY IN THE JOB SEARCH PROCESS

contributor:
Rosenthal, Carolyn J.
Sociology

subject: Sociology Sociology

abstract: Given the aging of the Canadian workforce and the trend for unemployed older workers (aged 45 to 65) to take considerably longer than younger ones to become re-employed, the purpose of this dissertation is to examine the importance of age in the job search process, how age influences identity when searching for work, and the management techniques used by older workers to obtain employment. There is little qualitative research generated in a Canadian context that examines the views of older workers themselves. Thus, this research uses qualitative methodologies (i.e. 30 semi-structured interviews supplemented by 35 hours of participant observation) and an interactionist framework, to contribute new insights into older workers' job search process. Findings indicate that study participants feel employers discriminate against them in the hiring process through both subtle and overt mechanisms related to employers' ageist stereotypes concerning skills, training, adaptability or flexibility, and financial costs. Respondents believe that employers use specific wording in job advertisements, choose candidates to interview by assessing age in applicants' resumes, further assess age in the interview setting, and use an ageist discourse. With respect to the impact of age on identity in the job search process, the ata suggest that once participants perceive they have been labelled "old" by others (i.e. potential employers and personnel at older worker programs) they begin to define themselves as "old" and become susceptible to identity degradation. These findings highlight the paradoxical nature of the job search process-Individuals go to older worker programs for assistance, yet some of the experiences encountered during attendance at these programs mirrored many experiences encountered with discriminatory employers. Despite this occurrence, most who experience identity degradation are able to successfully negotiate their identities by drawing on social support, attending older worker programs, changing their identities, maintaining their key roles, and altering their overall mental outlook. Finally, in an attempt to avoid being considered "old" when searching for work, respondents develop "counteractions" and "concealments". These age-related management techniques are believed to counteract employers' ageist stereotypes by maintaining skills and changing work-related expectations, and conceal age by altering resumes, physical appearance, and language. Overall, this dissertation advances the knowledge within the sociology of aging and work by using the richness of study participants' accounts to conceptualize the meaning and import of age in the job search process. Conclusions are drawn in relation to improving policies and practices that govern employers' behaviours in order to remove the structural barriers from older workers' route to re-employment.

abstract: Doctor of Philosophy (PhD)


title: EVOLUTIONARY CHANGE IN THREE SPECIES OF COMMON ROADSIDE PLANTS

contributor:
Dudley, Susan A.
Biology

subject: Biology Biology

abstract: Roadsides are an interesting and unusual habitat. Plants inhabiting these degraded areas are exposed to many easily identifiable and unnatural selection pressures. In this thesis, I examine the evolutionary ecology of three species (Dipsacus sylvestris, Hesperis matronalis and Asclepias syriaca) of common roadside plants. I collected seeds from several maternal plants from three oldfield and three roadside populations. In all six studies, I utilized a similar experimental design with analyses based on the variation between maternal families. I first compared the salt and manganese tolerance during germination of oldfield and roadside genotypes of all three species. I found that one population of H matronalis possessed a greater ability to tolerate high manganese levels than other roadside populations or oldfield populations. In addition, all three roadside populations of D. sylvestris had a greater ability to tolerate high salinity than oldfield populations. Some maternal families actually grew longer roots under high salinity than under control conditions. Examination of seed characteristics revealed a significant correlation among roadside maternal families in the amount of sodium leached from the seeds and the degree of salt tolerance or salt enhanced growth indicating that the salt tolerance could be a maternal effect rather than a genetic trait. I then attempted to discern the role of seed composition, which is controlled primarily by the maternal plant, in conferring salt tolerance to roadside populations of D. sylvestris. I leached the soluble components of the seed prior to salt exposure and then compared the ability of oldfield and roadside families to tolerate high salinity. I found that there were several salt tolerance mechanisms present among the roadside populations and that the maternal environment was likely involved in conferring the salt tolerance in some instances. I established a reciprocal transplant experiment between the roadside and oldfield involving all three species. I did not observe any evidence that adaptation to roadside conditions had occurred in roadside populations of any of the three species. However, the experiment was established in the late spring after the peak salinity levels. I speculated that adaptations in D. sylvestris to the high salinity of roadside soils may be visible if the seeds spent the winter and early spring in the field. I then established a second reciprocal transplant experiment involving only D. sylvestris between the oldfield and the roadside but planted the seeds in late fall to early winter. Again, I observed no evidence of local adaptation to the roadside environment. However, seed size, a trait controlled by the maternal plant, appeared to be very important in determining success during seedling establishment in both oldfield and roadside locations and among both oldfield and roadside genotypes. I then attempted to determine the role of tolerance to low water potentials in conferring salt tolerance in roadside populations of D. sylvestris. I found that there was no relationship between the ability to tolerate low water potentials and the ability to tolerate high salinity. An additional, unintended treatment of hypoxia inflicted by one of the osmotic stress treatments, also revealed that roadside populations of D. sylvestris possess considerable variation for the ability to tolerate hypoxia stress. Again, there was no relationship between hypoxia tolerance traits and salt tolerance or tolerance of low water potentials. I then questioned whether the high sodium levels present in the seeds of roadside D. sylvestris maternal families could be detrimental to germinating seeds. I compared the toxicity of the seed leachate of oldfield and roadside maternal families on other germinating D. sylvestris seeds from both the oldfield and the roadside. I found that the leachate of roadside D. sylvestris seeds inhibited the root growth of oldfield seeds but, the leachate of oldfield seeds had no impact on the root growth of roadside seeds. These studies strongly indicated that high salinity is a strong selection pressure in roadside communities. However, many stresses are impacting the vegetative community of roadside simultaneously. The selection pressures created by the stresses may be pushing populations in multiple conflicting directions. Different populations and even different families within populations are responding to different selection pressures. In addition, the lack of overlap in the tolerance traits suggests that adaptation to one selection pressure may come at the cost of adaptation to a different pressure. The action of the many different selection pressures may prevent local adaptation from being observed in field studies. In conclusion, it is very clear from these studies that roadside plant populations are evolving to better tolerate the unusual environmental conditions created by roads and a unique vegetative community is developing in this habitat.

abstract: Doctor of Philosophy (PhD)


title: Contractile properties of normal and dystrophic human skeletal muscles

contributor:
McComas, Alan J.
Neuroscience

subject:
Neuroscience and Neurobiology
Neuroscience and Neurobiology

abstract:
The aim of this study was to provide a better understanding of muscle function in healthy adult subjects (n=46) and in patients with myotonic muscular dystrophy (MMD; n=25) and limb-girdle muscular dystrophy (LGMD; n=20). Evoked and volitional contractions were examined in two opposing muscle groups in the leg, the ankle plantar-flexors (PF) and dorsi-flexors (DF). The following contractile properties were investigated under isometric conditions: (1) twitch torque, (2) twitch speed, (3) twitch potentiation, (4) voluntary muscle strength, (5) extent of motor unit activation during maximum voluntary effort and (6) muscle fatigue. In both control and dystrophic populations, striking contractile differences were observed between the PF and DF muscle groups. The DF muscles differed from the PF muscles in demonstrating smaller twitches, briefer contraction and half-relaxation times, marked twitch potentiation, more complete motor unit activation, and greater susceptibility to fatigue. Muscle fatigue was found to be caused by peripheral, rather than central failure; it occurred at the level of excitation-contraction coupling and/or the contractile machinery.

Comparisons of muscle contractile properties between patients with muscular dystrophy (MMD and LGMD) and their respective matched controls have disclosed that in any patient at a given stage, the dystrophic process may sometimes spare a muscle group while destroying another, regardless of their functions and fibre-type compositions. Furthermore, both groups of dystrophic patients showed normal twitch potentiation and muscle fatigue behaviour.

Apart from providing comprehensive information on normal and dystrophic skeletal muscles, this study constitutes a non-invasive and quantitative method for monitoring the time course of human muscular dystrophy and for assessing the benefits of any future therapy.

abstract: Doctor of Philosophy (PhD)


title: The Idea of the Absence of God in Simone Weil

contributor:
Vallée, Gérard
Religious Studies

subject: Religion Religion

abstract: Our purpose in this study is to show that the absence of God in this world, or the non-intervention of God in this world, is the idea par excellence which is at the heart of Simone Weil's thinking about man's situation in this world. To be very specific, our purpose in this study is to understand the significance of Weil's thinking about the idea of the absence of God in the context of thinking with truth at the same time about the affliction of men, the perfection of God, and the link between the two; or, to express the same thing in different terms, our purpose is to understand the significance of Weil's thinking about the idea of the absence of good in the context of thinking with truth at the same time about necessity, necessity's indifference to the good, and how necessity and the good can be reconciled. What this means, in effect, is that our entire study of Weil is essentially an explication of the relationship that she sees as existing between the question of necessity and Christ's cry of dereliction on the Cross. Not only is Weil's thinking about the idea of the absence of God completely unintelligible apart from a comprehensive understanding of her thinking about necessity, but further, her thinking about necessity is ultimately unintelligible apart from her thinking about Christ's cry of dereliction. More importantly, Christ's cry of dereliction is for Weil the most consummate expression of the absence of God; it expresses the 'absence of God from God', and what this means, as our study will endeavour to show, is that the idea of the absence of God cannot be thought without at the same time thinking the idea of the presence of God. In other words, the idea of the absence of God cannot be thought without at the same time thinking the idea of incarnation. To attempt to understand what Weil is saying about the idea of incarnation, especially in relationship to her thinking about the question of necessity, is to attempt to understand an aspect of Weil's thought which has neither been dealt with in any detail nor analyzed in any depth. To attempt to understand what Weil is saying in this context is, finally, to attempt to understand what she means in thinking that the absence of God in this world is the reality of God, that this world, in so far as it is entirely empty of God, is God Himself, and finally, that necessity, in so far as it is absolutely other than the good, is the good itself.

abstract: Doctor of Philosophy (PhD)


title: Lifetimes of Superdeformed States in 38 Ar

contributor:
Waddington, J. C.
Physics

subject: Physics Physics

abstract: Light nuclei provide an ideal laboratory for the study of the interplay between collective and single-particle interactions of nucleons. This thesis provides evidence via the lifetimes of states that the light nucleus 38 Ar undergoes superdeformation. Two highly deformed bands have been identified, one with a deformation parameter /32 = 0.30 ± 0.03. The deformation parameter of the more excited and more deformed band is less well measured, and it falls between /32 = 0.68 and /32 = 0.95. Superdeformation, the phenomenon in which a nucleus takes on an elongated shape with one axis approximately twice as long as another, occurs when nuclei are experiencing extreme conditions, particularly high angular momentum. The superdeformation of the nucleus 38 Ar is especially interesting because there is ample opportunity for interactions between superdeformed structures and normal deformed structures.

abstract: Doctor of Philosophy (PhD)


title: INVESTIGATING THE MOLECULAR MECHANISMS OF BCL-2 AND BAX IN THE REGULATION OF APOPTOSIS

contributor:
Andrews, David W.
Biochemistry

subject: Biochemistry Biochemistry

abstract: The molecular mechanism by which the Bd-2 family of proteins regulates the complex process of apoptosls is unknown. One insight into the function of these proteins is their requirement for membrane localization to regulate cell death. Bd-2, the prototype of the family, is localized the endoplasmic reticulum (ER) and mitochondria. By examining the contribution of ER localized Bcl-2 in the regulation of apoptosis; two spatially distinct cell death pathways were identified. One pathway is characterized by the early loss of inner mitochondrial membrane potential and is inhibited by ER localized Bc1-2. The other pathway, not inhibited by ER localized Bcl-2, is characterized by the mitochondrial translocation of the cytoplasmic pro-apoptotic protein Bax. On mitochondria Bax oligomerizes inducing the release of cytochrome c. This mitochondrial pathway is influenced by the expression of the oncogene Myc, specifically, Myc is required for the transition from monomeric, membrane bound, Bax to oligomeric active Bax. This activation ofBax is not mediated by changes to its membrane topology as both monomeric and oligomeric membrane bound Bax adopts a multi-spanning membrane topology with helices a5, a6 and a9 partially inserted into the lipid bilayer. These studies have demonstrated that the function ofBcl-2 at the ER is dependent on apoptotic agonist; Bax activity at mitochondria is influenced by a Myc regulated factor and activation of Bax is not mediated by changes in this proteins membrane topology. Combined these studies have provided valuable insight into both the complexity and molecular mechanisms of Bd-2 proteins in the regulation of apoptosis.

abstract: Doctor of Philosophy (PhD)


title: ¹²⁷I Mössbauer Spectroscopic Studies of Some Cations and Anions of Iodine

contributor:
Birchall, T.
Chemistry

abstract:
The ¹²⁷I Mössbauer spectra have been recorded at liquid-helium temperature for several series of iodine compounds. The Mössbauer spectra of a number of apparently cubic inorganic iodine compounds were measured and many were found to give abnormally broad lines. This was attributed to distortions from true cubic symmetry present in the compounds. KI gave the narrowest line and it was selected as the reference compound for ¹²⁷I Mössbauer spectroscopy.

The Mössbauer spectra of a series of linear iodine compounds, including the trihalide [X-I-Y]ˉ anions were measured and the magnitude of the quadrupole coupling constant was found to vary with the electronegativity of the attached ligands. Semi-empirical relationships had been developed to convert isomer shifts and quadrupole coupling constants into s- and p-orbital populations and these relationships have been re-established using the data for these linear iodine compounds. It was found that these semi-empirical relationships do not have general applicabilty when they were tested with a series of interhalogen cations and some iodine-chalcogen cations.

Several new interhalogen cations of iodine were also prepared and characterized. The ¹²⁷I Mössbauer parameters for these square planar iodine (I:I) cations revealed that, while secondary or bridging interactions are important in determining the sign of the quadrupole coupling constant, it is the primary bonds to iodine which determine the magnitude of the quadrupole coupling constant.

Finally, ¹²⁷I Mössbauer spectroscopy was applied to some interesting chemical problems. Mössbauer measurements on frozen solutions of [I₂]⁺ suggest that the new species formed is a square or rectangular dimer of [I₂]⁺, namely [I₄]²⁺. ¹²⁷I Mössbauer measurements in conjunction with recent ¹²⁹Xe and ¹²⁵Te NMR and ¹²⁹Xe Mössbauer have conclusively shown that the 0TeF₅ ligand is less electronegative than -F.

abstract: Doctor of Philosophy (PhD)


title: Synthesis and Characterization of Polyethylenes by Nickeldiimine and Metallocene Catalysts

contributor:
Zhu, Shiping
Chemical Engineering

abstract: Polyethylene (PE) synthesis has shown tremendous progress towards the production of polymers with innovative chemical and physical properties as a consequence of the development of new classes of single-site catalysts, including metallocene and the more recently developed nickel-diimine catalysts. This thesis describes the synthesis and characterization of a series of PE materials using a variety of metallocene and nickel-diimine catalysts. The main objective of this thesis work is to develop a better understanding of the influences of polymerization conditions and catalyst systems on polymer properties. A detailed investigation of the polymerization of ethylene by (adiimine) nickelCII) catalysts was first carned out. The catalysts used were ((ArN=C(An)-C(An)=NAr)NiBr2 and (ArN=C(H)- C(H)=NAr)NiBr2; where An = acenaphthene and Ar = 2,6-(i-PrhC6H3). Changes in the a-diimine backbone structure showed remarkable effects on the polymer microstructure as well as catalyst activity. For all the three catalysts, increasing ethylene pressure or reducing polymerization temperature led to a reduction in the chain walking rates, and thus reduced the melting temperature and crystallinity of the polymer produced. A Nila-diimine catalyst, 1,4-bis(2,6-diisopropylphenyl) acenaphthene diimine nickel(II) dibromide was then supported on MMAO-treated silica to produce short chain branched PEs by ethylene polymerization. The supported catalyst gave far lower activity than the homogeneous catalyst. Depending on polymerization conditions, two active site populations were observed during polymerization using supported catalyst; one remained fixed on the surface of the support, and the other was extracted from the support exhibiting the same polymerization behavior as the homogeneous catalyst. A tandem homogeneous catalytic system was also used for the synthesis of ethylene-l-hexene copolymers from ethylene as the sole monomer. The catalytic system employed the tandem action between an ethylene trimerization catalyst, (11 5- CsH4CMe2C6Hs)TiCh(1)/MMAO, and a copolymerization metallocene catalyst, [(115-sMe4)SiMe2CBuN)]TiCh(2)/MMAO. During the reaction, VMMAO in situ generated I-hexene with high activity and high selectivity and simultaneously 2/MMAO copolymerized ethylene with the produced I-hexene to generate butyl branched PE. By simple manipulation of the catalyst molar ratio and polymerization condition, a series of branched PE samples were efficiently produced. A binary catalyst system, consisting of a Nila-diimine catalyst, 1,4-bis(2,6-diisopropylphenyl) acenaphthene diimine nickel(lI) dibromide(l) and a zirconocene catalyst, rac-ethylenebis(indenyl) zirconium dichloride](2), was developed to synthesize a series of reactor blends of linear and branched PEs. The nickel diimine catalyst generated branched PE, while the zirconium catalyst produced linear PE. At various levels oftemperature, ethylene pressure, and Catalyst 2 fraction, PE blends with different melting behaviors were produced. GPC-V analysis of the PE samples showed monomodal molecular weight distributions with narrow polydispersities.

abstract: Doctor of Philosophy (PhD)


title: POLYMER CAPSULES BY LIVING RADICAL POLYMERIZATION

contributor:
Stover, Harald D.
Chemistry

subject: Chemistry Chemistry

abstract: A novel technique for encapsulation by in situ suspension Atom Transfer Radical Polymerization (ATRP) was developed. The capsule wall-forming material was a crosslinked terpolymer based on diethylene glycol dimethacrylate (DEGDMA) crosslinker; a hydrophobic oil-soluble monomer, methyl methacrylate (MMA), and either polar oil soluble poly(ethylene glycol) monomethyl ether methacrylate (MPEGMA) or water soluble poly( ethylene glycol) methacrylate (PEGMA). Narrow disperse (MwlMn < 1.2) and linear MMAiMPEGMA (9 - 30 mol% MPEGMA) and MMAIPEGMA (10 - 40 mol% PEGMA) copolymers of controlled molecular weight (MW) were prepared in high yields (>90 and >80 wt.%, respectively) using tosyl chloride initiator and Cu(I)Cl - dinonyl dipyridyl catalyst in diphenyl ether (DPE) solution at 70 DC. Copolymer analysis by IH and l3C NMR showed quantitative incorporation of both MPEGMA and PEGMA into the copolymers. Suspension copolymerization of MMA with either MPEGMA or PEGMA in a DPE oil phase also yielded narrow disperse (MwlMn < 1.3) copolymers of controlled MW in high yields (>80 wt.%), indicating that the ATRP catalyst was confined to the oil droplets. IH NMR confirmed the incorporation of both MPEGMA and PEGMA into the copolymers forming in the oil phase, despite significant partitioning of MPEGMA and especially PEGMA into the water phase. In crosslinking suspension ATR terpolymerizations of MMA, MPEGMA and DEGDMA cross linker, a transition in particle morphology from solid to hollow and multi-hollow capsular particles was observed upon increasing the MPEGMA content (0 - 31 mol%) in the feed. Analogous conventional free radical polymerizations (CFRP) gave only solid polymer particles. Similarly, ATR terpolyrnerization of MMA, PEGMA and DEGDMA gave capsules at 17 mol% PEGMA, while CFRP only gave capsules at higher amounts PEGMA (24 mol%) in the feed. Both systems illustrated that the slow rate of ATRP favors the thermodynamically favored capsular morphology when compared to analogous CFRP experiments, and hence should permit capsule formation for more polar fiUs compared to CFRP.

abstract: Doctor of Philosophy (PhD)


title: IMMUNIZATION VIA THE COLONIC MUCOSA USING ADENOVIRAL VECTORS

contributor:
Gauldie, J.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: Sexually-transmitted diseases (STDs) are among the most common causes of illness in the world. The annual incidence of STDs is rising, from 250 million in 1990 to 340 million in 2002. Viral infection is a frequent cause of STDs and the mucosal surfaces are the natural sites of transmission of viruses. Both genital and rectal tracts are involved in transmission of viral SIDs. To infect a host, a virus has to penetrate mucosal immunologic barriers, including lumenal immunoglobulin A (lgA) intervention, epithelial defenses, and lamina propria (LP) lymphocyte- ediated protection. The breach of the mucosal immune system can lead to virus spreading to the rest of the body, thereby causing life-threatening disease. Induction of effective mucosal immunity is essential for the host to control local viral infection and prevent SID development. Immune responses are initiated when pathogen-derived antigen (e.g., viral antigen) is encountered and taken by antigen-presenting cells (APes), especially dendritic cells (Des). After antigen processing, Des present immunogenic determinants to and activate naIve lymphocytes in mucosal lymphoid tissues. Activated lymphocytes leave the lymphoid tissue and, via the bloodstream, migrate to the LP. These effector cells exert a series of immune functions, such as cytokine production, cytotoxicity and antibody secretion. Accordingly, the mucosal immune system is divided into the inductive and effector site. Gut-associated lymphoid tissues (GALT) represent the inductive site of the gastrointestinal (GI) system. The GALT within the rectal mucosa mainly consists of iliac lymph nodes (lLN) , Peyer's patch-like aggregated lymphoid follicles (ALF) and isolated lymphoid follicles (ILF). The ILN have been identified as the principal inductive site, whereas the role for mucosally located lymphoid follicles remains poorly understood. To elicit specific mucosal immune responses against virus infection, a viral antigen must be introduced into the mucosal immune system, importantly the inductive site. Efficient antigen delivery ensures the success of inducing effective mucosal immunity. Both the mucus layer and the integral epithelial monolayers form barriers against the passage of proteins and particulate matter across the epithelium. Previous studies demonstrated that these barriers could be overcome by mucus removal with ethanol treatment followed by utilizing viral vectors such as replication-deficient adenoviral vectors (Adv) engineered to encode heterologous antigen genes. Adv can infect a broad range of mammalian cells, including human and ~ouse epithelial cells, and has proved to be efficient in transferring genes to the colonic mucosa. It has been discovered that mucosal immunity can be induced at multiple mucosal sites, but rarely via a systemic route. This phenomenon is largely due to the mechanism of the common mucosal immunologic system (CMIS), within which activated mucosal lymphocytes migrate from one mucosal site (e.g., the upper respiratory tract mucosa) to another (e.g. the genital tract). Thus, the concept of CMIS is used as a guiding principle for mucosal vaccine design. However, emerging results have suggested that distant mucosal immunization is less effective than local immunization and that CMIS might comprise several anatomical-based grouped networks having different lymphocyte homing mechanisms. In this context, the vaginal (local mucosal) immunization regimen might improve local protection against genital STDs. Following the similar logic, rectally-induced immune responses might have potential to combat rectal STD infections.As both genital and rectal mucosae are drained by the ILNs, the putative genito- ectal associated lymphoid tissue, rectal immunization might be an alternative solution to genital immunization, especially to deal with the problem of immunization in the male genitourinary tract. The major goal of this study was to evaluate the effects of Adv-based local mucosal immunization via the rectum of mice in the induction of mucosal immunity against virus infection at the rectal as well as genital mucosa. non-Invasive intrarectal (IR) delivery method (pipetting and Dermabond® following a ethanol enema) for Adv was developed in the present study to provide better gene transfer for induction of mucosal immune responses. The first approach was to reinvestigate gene transfer to the mouse colon after intrarectal (lR) administration. The transgene was found highly expressed at days 1-3 and mainly confined to the colon. Gene expression was not only identified within the epithelium but also immediately beneath the epithelium, probably due to the penetration of Adv through epithelial cells. Mucosal immune responses were examined in an antigen model using ovalbumin (OV A). After IR immunization with Adv encoding OVA (AdOV A), the frequency of LP interferon (lFN)y secreting cells was detected as early as day 4, and continually progressed upward. The appearance of ILN IFN-y-secreting cells was transient, and this was mirrored by the ILN cytolytic activities. CDS+ T cells were stimulated to produce IFN-y, and cytolytic activities depended largely on CDS. Also, IR immunization with Adv induced Thl T-cell responses and local production of specific IgA. When challenged with recombinant vaccinia virus expressing OV A, immunized mice completely controlled local viral infection and prevented virus dissemination from the rectal tissue. Thus, an infectious mouse model of herpes simplex virus type 2 (HSV -2) given via the rectum was developed in the study and used to further validate the IR immunization regimen. Mice immunized with Adv encoding glycoprotein B (AdgB) were protected from rectal challenge of HSV -2 at absolute lethal doses. Clinical pathology and virus replication were remarkably reduced and virus-shedding period was significantly lessened. CDS+ T cells, IFN-y and interleukin (lL)-12 appeared to play an essential role in such protective immunity. Protection of mice against HSV-2 challenge in the vaginal tract was also achieved, thus indicating that rectal immunization could also confer protective genital immunity. In comparison with the intranasal (distant mucosal) and subcutaneous (systemic non-mucosal) immunization, rectal immunization proved to be more effective in the induction of rectal immune responses including the frequency of IFN-y secreting cells and IgA production, and to provide better protection against rectal or vaginal HSV-2 challenge. All these results underscored the importance of applying local mucosal immunization to induce mucosal immunity at both rectal and genital tracts. In conclusion, IR administration with Adv by the new delivery method efficiently transferred antigen genes into the rectal mucosa and elicited protective local immunity to virus challenge. The present study provided evidence that rectal (local mucosal) immunization regimen was a better vaccination strategy than distant mucosal and systemic non-mucosal immunization to provide both rectal and genital protection against viral infection. Thus, the present approach supports the view that route is a critical determinant of vaccination and, furthermore, represents fertile ground for future studies of mucosal vaccination via the rectal mucosa.

abstract: Doctor of Philosophy (PhD)


title: THE INTERACTIONS OF PRESSURE SENSITIVE ADHESIVE WITH PAPER SURFACES

contributor:
Pelton, Robert
Chemical Engineering

abstract: The interactions of pressure sensitive adhesive (PSA) with paper surfaces were investigated by using peel adhesion testing as a probe. The objectives of this work were to reveal the fracture mechanism of paper/adhesive laminates and establish the links between paper properties and the performance of PSA tapes. Particular attention was given to analyzing paper/adhesive peel curves. It was found that the peak peel force (i.e. the maximum force in a peel curve) was more effective for analyzing peelings from paper than the conventionally used steady-stateforce. Based on this, we developed a new peel data analysis method by which the overall peel behavior of a paper/adhesive combination is conveniently summarized by plotting the log peak peel force as a function of the log peel rate. This approach yielded a generalized peel curve consisting of a rate-dependent interfacial domain and a rate independent failure domain. The force generated at the paper surface in peeling was analyzed; it was found to be proportional to the overall peel force. By varying peel rates, the two types of forces were shown to have a linear relationship for the two tape types and two paper types investigated. This result justifies the use of the easily measured peel force as an estimate of the real force at the interface. Rapid peelings induce paper delamination in which paper is separated into two layers. Microscopic analysis revealed that there are three sub-processes: 1) initially, the top layer of fibers, beneath the peel front, is lifted; but, 2) it must be fractured in order for the fiber layer to be peeled from the paper sheet; and, 3) in the steady-state delamination region, the top layer of paper fibers are peeled from the paper. Processes 1 and 2 only occur initially, whereas delamination (process 3) occurs continuously during peeling. The initiation of paper delamination from the surface was found to require more than double the steady delamination force because of the need to fracture the top fiber layer (process 2). For the first time, links between paper properties and the performance of PSA have been identified by the use of advanced statistical analysis and the newly developed approach for analyzing paper/adhesive peel curves. The paper properties influencing peel force in the interfacial failure domain are, primarily, the paper surface chemistry characterized by oxygen/carbon ratio (determined by X-ray photoelectron scanning analysis) and, secondarily, the surface roughness. The governing paper property in the paper failure domain is the paper internal (Scott) bond strength. The log-log slope in the interfacial failure domain is independent of paper properties, and it is found to be governed by adhesive rheology. Finally, the fundamental research was extended to solve a practical problem. We developed a new peel-based test for paper surface strength, in which the force required to initiate paper delamination when peeling a strip of adhesive tape is proposed as a measure of paper surface strength. This method makes it possible to compare surface strength with other strength properties of paper. Further, this surface strength was found to be independent of peel rate and strongly correlated to the IGT strength (an industrial measUre of paper surface strength).

abstract: Doctor of Philosophy (PhD)


title: Modeling the Saturated Bipolar Transistor

contributor:
Chisholm, S.H.
Barber, H.D.
Electrical Engineering

subject:
Electrical and Electronics
Electrical and Electronics

abstract:
In this paper an analysis of the saturated bipolar transistor is presented, in the situation where the dc collector current is zero or close to zero. In this particular case, the device is referred to as a zero-biased transistor (ZBT). The analysis is based on a version of the integral charge-control model of Gummel and Poon.

Through analytic solution of the model equations and computer simulation, the dc collector-emitter voltage, small-signal collector-emitter conductance, and second and third-order nonlinear distortion are examined over a wide range of base currents. Both the ac and dc characteristics are found to be dominated by different physical phenomena at different levels of IB. The effects of the parasitic substrate transistors on device operation are also examined. Criteria for acceptable performance are established with a view towards practical applications.

A number of applications for the ZBT have been suggested, particularly where a low-power small-signal variable-impedance element is required. Perfomance of the device in small-signal attenuator and a feedback amplifier are discussed. The effects of a fixed parallel resistance and a finite base-drive impedance on device performance are investigated.

The results are found to describe the measured dc behaviour at low and moderate base currents for a family of lateral p-n-p transistors having symmetric forward and reverse-active properties. Similarly, low-frequency ac behaviour is well described at low and moderate base currents. Suggestions for future work are included.

abstract: Master of Engineering (ME)


title: Hydrochemistry, etc. of the Caves Branch Karst, Belize

contributor:
Ford, Derek C.
Geography

subject: Geography Geography

abstract:
An extensive karst developed on Cretaceous limestones in Belize, Central America, was the site of a hydrochemical, hydrologic, and morphologic study. This thesis describes the results of analysis of several hundred water samples from this humid tropical environment (mean annual rainfall - 2376 mm; temperature - 24.5°C). An unusual positively correlated discharge/total hardness loading curve in a major cavern conduit is explained as due to a two-component mixing model. Hydrologic modelling, soil CO₂ sampling, and discriminant analysis were used to infer the interior structure of a karst aquifer. Minimum effective porosity was determined to be 0.7%. Mean areal hardness of 187 mg/L (as CaCO₃) was found for springs draining the aquifer, indicating a denudation rate of about 90 m³/Km²/year. Aqueous Pco₂ of these springs was 1.1%, significantly higher than the 0.7% of mean karst soil CO₂ levels. This implies open system calcite solution evolution and/or internal CO₂ production within the aquifer.

Various morphologic analyses suggest the cockpit-type surfaces of numerous karsts in the tropics may be significant due to disaggregation of existing topographic lows originally formed by creation of a fluvial topography. These fluvial valleys acted as favorable sites for concentration of aggressive water and consequent cockpit formation.

Over 40 km of cavern passage were explored in the Caves Branch, including one of the largest tropical cavern systems known. Cavern development appeared to have been chiefly influenced by regional fracture patterns and topographic dip. The present development was completed by at least 140,000-215,000 years B.P., according to results of speleothems dated by the uranium/thorium disequilibrium method.

abstract: Doctor of Philosophy (PhD)


title: SYNTHESIS, CHARACTERIZATION AND PROPERTIES OF NOVEL POLYOLEFINS BY SINGLE-SITE CATALYSTS

abstract: Developments in single-site catalysts for olefin polymerization have offered unprecedented freedom in designing new polyolefins, controlling polyolefin structure, and tailoring materials properties. The main theme of this sandwich-style thesis is the synthesis, characterization, and properties of a novel series of polyolefin materials that have unique chain structures and superior materials properties. These polyolefin materials were respectively prepared with a variety of recently developed single-site catalysts. High-strength polyethylene fibers were in situ synthesized Via nanoextrusion polymerization of ethylene with a mesoporous particle (MCM-41) supported titanocene catalyst, Cp2TiCh. The unique nanotube structure prevented the conventional folding of growing polymer chains inside the nanotubes and thus led to the formation of polyethylene nanofibrils with unique extended chain crystalline structure. Further aggregation of nanofibrils resulted in macro-scaled polyethylene microfibers. The morphological properties of nascent PE fibrous materials were investigated extensively using ESEM, XRD, and DSC. Tensile mechanical analyses showed that the polyethylene microfibers produced in this nanofabrication process exhibited tensile strength comparable to those of polyethylene fibers fabricated through post-reactor processing methods. A Ni/a-diimine catalyst, 1,4-bis(2,6-diisopropylphenyl) acenaphthene diimine nickel(II) dibromide, was supported on various mesoporous particles (MCM-41 and MSF) having different nanotube structures to produce short chain branched polyethylenes by ethylene polymerization. The effects of catalyst supporting methods and nanotube structure of the mesoporous particles on the catalyst impregnation were studied. In ethylene polymerization, some active sites of the supported catalysts showed reduced chain walking ability compared to the homogeneous counterparts. The effects of nanotube structure of mesoporous particles on ethylene polymerization activity, polymer property, and polymer particle morphology were investigated. A series of branched polyethylenes with various chain topologies were prepared with chain walking Pd- and Ni-diimine catalysts, [(ArN=C(Me)C(Me )=NAr)Pd(CH3)(NCMe )]SbF 6 and (ArN=C(An)-C(An)=NAr)NiBr21 MMAO, respectively, under different reaction conditions. In addition to topological characterizations using GPC-VIS and \3C NMR techniques, a rheological study was conducted to investigate their unique rheological behaviors. The high molecular weight polyethylenes prepared under low ethylene pressures (0.2 and 1 atm at 35°C) with the Pd-diimine catalyst exhibited extremely low viscosity and typical Newtonian flow behavior, suggesting dendritic topological structures. Changing the polymer chain topology by varying reaction conditions and/or changing the catalyst metal center significantly affected polymer rheological properties. These novel dendritic polyethylenes have potential in such applications as lubricants, printing materials, and polymer processing additives. A one-step polymerization process employing binary tandem catalyst systems, (,,5 -C5H4CMe2C6H5)TiCh/MMAO coupled with [(,,5_ C5Me4)SiMelBuN) ] TiCh/MMAO or rac-Me2Si(2- eBenz[e ] Ind)2ZrChl MMAO, was applied and investigated for an efficient production of ethylene- exene copolymers with ethylene as the sole monomer. This strategy utilized a tandem action between the two single-site catalysts. During the polymerization, the trimerization catalyst, (,,5 -C5H4CMe2C6H5)TiCh/MMAO, trimerized ethylene to form I-hexene, while the other metallocene catalyst component efficiently copolymerized the in situ produced I-hexene with ethylene to form butyl branched polyethylenes. A simple adjustment of the molar ratio of catalyst components, catalyst combination, and reaction conditions effectively regulated branching density in the copolymers. The branching structure of the copolymers was confirmed and characterized using 13C NMR and DSC. This one-step process has clear advantages over the two-step procedure for linear low density polyethylene (LLDPE) production. A binary catalyst system, consisting of a bisiminepyridine iron catalyst [(2-ArN=C(Me))zCsH3N]FeCh (Ar = 2,6-C6H3(Me)z)/MMAO and a zirconocene catalyst rac-Me2Si(2-MeBenz[e]Ind)zZrCh/MMAO, was developed to synthesize isotactic polypropylenes grafted with atactic side chains. The iron catalyst in situ generated I-propenyl ended atactic polypropylene macromonomer, while the zirconium catalyst incorporated the macromonomer into the copolymer. The effects of reaction conditions, such as catalyst addition procedure and ratio of the two single-site catalysts on branching frequency were studied. Copolymer samples having branching densities up to 8.6 aPP side chains per 1000 iPP monomer units were obtained. Novel long chain branched isotactic polypropylenes were produced by propylene copolymerization with a very small amount of non-conjugated diene, 1,7 -octadiene or I,9-decadiene, with a single-site metallocene catalyst, racMe2Si(2-MeBenz[e] Ind)2ZrCh/MMAO. By controlling the amount of dienes in the polymerization system, isotactic polypropylenes with different long chain branching densities were effectively produced. Rheological studies showed that the presence of long chain branching significantly enhanced polymer melt strength and improved polymer processibility. This in-reactor method is more effective and convenient than other post-reactor processes used for producing LCBedPP.

abstract: Doctor of Philosophy (PhD)


title: Steric Factors in 1-Naphthonitrile-Olefin Exciplex Formation

contributor:
McCullough, J.J.
Chemistry

subject: Chemistry Chemistry

abstract: The fluorescence quenching and photochemistry of 2-methyl-, 4-methyl- and 6-methyl-1-naphthonitrile with tetramethylethylene have been studied in benzene and ethyl acetate. Stern-Volmer constants (benzene solvent) are 10.1, 15.7 and 9.0 M‾¹, respectively, showing that quenching is insensitive to position of the methyl group. Exciplex emission was observed in each case, and exciplex lifetimes were measured by the technique of time-correlated single photon counting. The methyl-1-naphthonitriles react with tetramethylethylene to give 1-cyano-7,7,8,8-tetramethyl-2,3-benzobicyclo[4.2.0]octa-2,4-diene derivatives, and limiting quantum yields were determined. Quenching with biacetyl showed that the exciplex is an interm0ediate in the cycloaddition reaction involving 4-methyl-1-naphthonitrile. Also, no triplets were formed from the decay of the exciplex. The decay rate constants for deactivation of the exciplex were measured. The bichromophoric molecules 2,3-dimethyl-2-butenyl-1-cyano-2-methylnaphthyl ether, 2,3-dimethyl-2-butenyl 1-cyano-4-methylnaphthyl ether and 2,3-dimethyl-2-butenyl 1-cyano-6-methylnaphthyl ether, in which the chromophores are linked by a three atom chain, were synthesized. All three show strong quenching of the monomer (naphthonitrile) fluorescence and weak exciplex emission. The three bichromophoric compounds also react on irradiation giving internal cycloaddition products. The structures of the latter were determined, and the structure work is described. Comparison of quantum yields for intra-molecular cycloaddition with limiting quantum yields for the bimolecular cases, indicate that the three-atom chain greatly expedites collapse of the exciplexes to products in these systems. The results are discussed within the context of the model for exciplex formation and decay introduced by Michl.

abstract: Doctor of Philosophy (PhD)


title: Magnetic Excitations in the Diluted Ferromagnet Ni₂Mn₀.₈V₀.₂ˢⁿ

contributor:
Stager, C.V.
Physics

subject: Physics Physics

abstract: The magnetic excitation spectrum of the randomly diluted ferromagnet, Ni₂Mn₀.₈V₀.₂Sn, has been measured by neutron inelastic techniques. The frequencies are reduced from those observed for the non-diluted ferro-magnet, Ni₂MnSn, by a factor that depends on wavevector. The shape of the frequency shift is characteristic of an in-band resonance. Computer simulation calculations have been performed for large finite arrays (~15,000 spins) including up to third neighbour interactions. The predicted frequencies agree with experiment. The calculations show a resonant effect however it is not as pronounced as the observed effect.

abstract: Doctor of Philosophy (PhD)


title: Models For the Low-Energy K-N and π-N Interactions

contributor:
Nogami, Y.
Physics

subject: Physics Physics

abstract: Models are constructed and studied for the low-energy interactions in each of two hadronic systems, the KN and the πN. In the low-energy KN system, there appears the resonance Λ(1405); in the low-energy πN system, the resonance Δ(1232). Each of the models is so constructed that the corresponding resonance appears, not merely as a composite state of the hadrons in the system in which it is formed, which is how it appears in older and more conventional models, but as a state to which there is also a contribution from the constituent quarks. The models for the KN interaction is studied primarily with a view to explaining the recent and unexpected kaonic H-atom result - something which no existing model is able to do. The model for the πN interaction is used to study πN scattering in the (3,3) channel.

abstract: Doctor of Philosophy (PhD)


title: Influences of System Imperfections on the Performance of Cam-Follower Systems

contributor:
Newcombe, W. R.
Mechanical Engineering

subject:
Mechanical Engineering
Mechanical Engineering

abstract:
The cam-follower mechanism is a most important machine element used to control the complicated motion of machine parts, and the accuracy of the motions and subsequent machine performance depends on the cam-follower output. Imperfections in the system affect this output, and an investigation of all possible effects is carried out here through the analytical and simulation means developed.

The imperfections considered here include all factors that cause a design to deviate from the theoretical model. These factors have generally been neglected in the past because of their complexity. They are classified in the following three categories:

1. Geometrical Imperfections

a) Machining or manufacturing errors: Tolerances

b) Backlashes or clearances

2. Kinematic Imperfections

a) Non-constant angular velocity of cam

b) Impossibility of a perfectly manufactured cam profile

c) Asymmetry between rise and return period

3. Dynamic Imperfections

a) Inertial mass

b) Flexibility of system elements

c) Energy dissipation

The performance of the system is indicated by its responses, such as time responses (displacements, velocities and accelerations) and inertial responses (contact forces or stresses, torques and inertia forces).

To investigate the effects of the imperfections, the mechanism of a translating roller follower-cam system driven by a motor through a rigid coupling is simulated on a digital computer dynamically and stochastically. The dynamic simulation, which will produce the effects of the kinematic and dynamic imperfections, is accomplished on the basis of an eleven degree of freedom model which was carefully devised to include all possible properties or factors concerning the real system behaviour, such as flexibility of cam shaft, non-constant angular velocity of the cam due to torsional vibration, jump phenomenon caused by inertia force, preloading of the retaining spring, cantilever effects of follower due to pressure angle, nonlinear damping, and the exact contact condition between cam and roller follower. In the model, an analytical method to calculate the spring constant of the interface between cam and follower is introduced by using Hertzian deflection characteristics. To analyse the effects of geometric imperfections which involve random characteristics, the ground and finished cam profile is modelled stochastically by generating normally distributed random numbers and applying a cubic polynomial spline function to obtain the cam profile.

Thus, the compounded effects of tolerances and flexibility in the system can be investigated.

The motion equations derived from the dynamic model and stochastic model consist of simultaneous nonlinear differential equations in which the factors having a random nature are implicitly included. To solve the motion equations the refined Runge-Kutta algorithm is utilized so that the computing accuracy can be controlled.

The PDP-11/34 minicomputer and its graphic peripheral devices are exploited by the overlay technique. Intermediate results are transferred to subsidiary memory while renewing the previously executed memory, so as to diminish the processing cost of the dynamic and stochastic simulation program as well as to compensate for the insufficient main memory.

Finally, the results of the simulation are analyzed and compared with the work of other researchers, in which the effect of an imperfect profile has usually been neglected.

abstract: Doctor of Philosophy (PhD)


title: Optimal Lattice Codes For the Gaussian Channel

contributor:
Anderson, J.
Buda, R. de
Electrical and Computer Engineering

abstract:
Lattices are used to construct a class of equal-energy codes for the Gaussian channel and the resultant error probability tends to zero for large n at all rates below channel capacity. The error probability is explicitly bounded for any given lattice code and then further further bounded for a general code using the Minkowski-Hlawka theorem of the geometry of numbers. Similar bounds are applied also to maximum-energy codes, to show that such lattice codes are near-optimal.

Finally, the error bounds are applied to explicit codes defined for all n=2ᵐ. These codes are shown to have a low Pℯ at rates higher than any previously attained.

abstract: Doctor of Philosophy (PhD)


title: An Atmospheric Dispersion Model For The Sudbury, Ontario, Area

contributor:
Kramer, J. R.
Geology

subject: Geology Geology

abstract:
The objectives of the study are to predict the relationship of atmospheric emissions from smelters to atmospheric and precipitation chemistry, and to lake water and sediment chemistry.

A mathematical model was developed and tested to simulate atmospheric, precipitation, lake water and sediment chemistry of selected lakes in an approximate 0.3 x 10⁶ square kilometre area around the city of Sudbury, Ontario.

The model consists of two basic parts; an atmospheric portion and a lake chemistry portion. The atmospheric model is a Gaussian crosswind distribution modification to a box model with a uniform vertical concentration gradient limited by a mixing height (for the far field). In the near field, plume rise and vertical dispersion terms are utilized. First order chemical reaction kinetics are utilized to model the production of hydrogen ion and sulphate ion by the oxidation of sulphur dioxide. Oxidation processes in both the gas phase and the liquid phase are incorporated.

Losses en route are accounted for by the incorporation of deposition mechanisms. Losses result from the operation of these mechanisms over a period determined by plume travel time from the source to the receptor. Separate wet and dry deposition mechanisms acting on the different physical phases of pollutant species in the atmosphere are considered. These include pollutants in the gas phase, the liquid phase (dissolved in cloud droplets) and particulates or aerosols.

The mass flux of pollutant onto a unit surface (loading rate) at the receptor is accounted for by the incorporation of deposition mechanisms. While the physical processes involved are the same as those producing enroute losses, loadings result from the operation of these mechanisms at the receptor over the time period of model operation.

The continued oxidation of sulphur dioxide in samplers after deposition is also modeled.

The model can be operated in the Gaussian crosswind mode or the box mode. Advection, dispersion and boundary conditions are described by using hourly and daily meteorological data from a series of meteorological stations in the study area. These data are preprocessed by a subprogram. Provision for six alternative schemes for combining the data from the meteorological stations are included.

Important improvements over previous models include

-computations for near and far field conditions in a single model

-direct linkage of crosswind dispersion to daily and hourly meteorological parameters.

-utilization of minimum and maximum input driving parameters and theoretical parameter measurement accuracy to realistically model the range of outputs

-direct linkage of the atmospheric model to a lake water and sediment model.

The second portion of the model is the lake model. Precipitation chemistry as calculated by the atmospheric model is related to lake water and sediment chemistry utilizing a mass balance approach and assuming a continuously stirred reactor (CSTR) model to describe lake circulation. In the model surface water, the epilimnion; and the hypolimnion are considered as a single unit.

All inputs to the lake model are determined by predicted atmospheric and precipitation chemistry, modified by hydrology, soil chemistry and sedimentation in the drainage basin. Lake model outputs are stream flow and sedimentation.

A field program was carried out to collect sediment and lake chemistry data with which to test the lake model. These observations of lake water and sediment chemistry, geological observations and measurements supplement atmospheric chemistry, precipitation chemistry, meteorological and topographic data and available literature concerning the Sudbury study area.

The study area chosen surrounds the smelters at Sudbury and Falconbridge. Eight pollutant species were selected for modeling--sulphur dioxide, sulphate ion, hydrogen ion, copper, nickel, lead, zinc and iron particulates. The INCO and Falconbridge copper/nickel ore smelters in the Sudbury, Ontario area are among the largest single sources of sulphur dioxide in the world, emitting approximately 1 percent of the anthropogenic total. Significant quantities of particulates containing iron, copper, nickel, lead and other trace elements are also emitted. Sulphur dioxide, copper, iron and nickel are important smelter emissions. Zinc and iron are also indicators of natural geological processes affecting atmospheric chemistry, while lead and zinc also provide indicators of urban processes other than smelter operation.

The Sudbury source is relatively isolated from other sources of comparable magnitude, and topographic and meteorological conditions are relatively uniform across the study area. This presents advantages for model verification.

The study area contains large numbers of accessible lakes in a variety of geological formations, including small unbuffered lakes in small bedrock basins in the Lorraine Quartzite formation. Several of these lakes were examined in comparison to large basin lakes with higher buffering capacities in order to effectively gauge the effects of atmospheric inputs from Sudbury on lakewater and sediment chemistry.

Results indicate that the model effectively predicts precipitation chemistry within approximately 150 kilometers of Sudbury. Predictions of precipitation chemistry range from approximately 22±36 percent of measured values for hydrogen ion to approximately 242±179 for copper. The average ratio of predicted to measured precipitation chemistry values is approximately 90±80 percent. Beyond 150 kilometres the effects of other pollutant sources begin to dominate. Utilization of Sudbury centered sources only in the model is invalid at these distances.

Predictions of precipitation chemistry are calculated from model predictions of atmospheric concentrations. Therefore the accuracy of the atmospheric concentration predictions defines an upper limit to the accuracy of the precipitation chemistry predictions. Therefore atmospheric concentration predictions will be at least as accurate as precipitation chemistry predictions. Results indicated that excellent prediction of atmospheric concentrations are achieved with the model within 80 kilometers of the smelters. Predictions of atmospheric concentrations range from approximately 69±26 percent of measured values for sulphur dioxide, to approximately 105±37 percent of measured values for nickel. The average ratio of predicted to measured atmospheric concentrations is approximately 81±21 percent.

Predictions of lake water chemistry are calculated from predictions of precipitation chemistry, hence the accuracy of precipitation chemistry predictions defines an upper limit to the accuracy of lake chemistry predictions. Results indicate that good predictions of lake chemistry are achieved with the model. Predictions of lake water chemistry range from approximately 10±6 percent of measured values for hydrogen ion, to approximately 270±265 percent of measured values for zinc. The average ratio of predicted to measured lake chemistry values is approximately 140±124 percent. Ratios of predicted to measured lake water chemistry exhibit a clear bimodal pattern for pH, copper, nickel, zinc and iron. pH predictions for large drainage basin lakes are high, and pH predictions for small drainage basin lakes are low. Geological controls of lake chemistry, especially of pH and the control pH exerts on trace metal chemistry, may account for this pattern. These results indicate that adequate lake chemistry modeling requires a more complex model then a simple CSTR mass balance.

Predictions of sediment chemistry are calculated from model predictions of lake water chemistry. Therefore the accuracy of sediment chemistry predictions are limited by the accuracy of lake water chemistry predictions. Results indicate that good predictions are achieved with the model. Predictions of sediment chemistry range from approximately 102±78 percent of measured values for nickel, to 263±228 percent of measured values for lead. The average ratio of predicted to measured sediment chemistry is approximately 166±122 percent.

abstract: Doctor of Philosophy (PhD)


title: Instability in Bending

contributor:
Duncan, J. L.
Mechanical Engineering

abstract:
Discontinuous yielding in the form of Lüder's bands in frequently observed in tensile testing to mild steel sheets. In these materials, instability or kinking may or may not be observed in bending operations and various theories have been proposed to relate the bending and tensile phenomena.

In this work, an extensive experimental investigation was performed on five samples of low carbon sheet steels. The main objective was to develop a new analytical model, based on the uniaxial tensile stress-strain curve that will predict the behaviour of these materials in pure bending. Two models appeared possible and the experiments performed suggested that one of these is an appropriate model for steels of this kind.

abstract: Master of Engineering (ME)


title: ELECTRONIC RETAILING: AN ANALYSIS OF WEB IMPACTS AND RELATIONSHIP MARKETING OPPORTUNITIES

contributor:
Head, M.M.
Business Administration

subject: Business Business

abstract: The Web brings enormous opportunities for retailers, where customer retention is important for e-tailing success. While relationship marketing (RM) and e-tailing are both active research areas, there is inadequate research on relationship marketing in e-tailing. This thesis was an effort to integrate the two areas of research, RM and e-tailing, and investigate online consumer RM issues. The focus of the thesis was to examine the Web factors that represent a significant impact on the retail market and contribute to online consumer RM. After addressing the research motivation and objectives in Chapter 1, Chapters 2 and 3 review RM and electronic marketing literature respectively. A hypothesized model is constructed in Chapter 4 to examine the effects of four online market characteristics (perceived shopping risks, perceived consumer power, perceived interaction, and perceived relationship investment) on consumer relational intention, through three important mediators (perceived switching costs, satisfaction, and trust). An empirical study, aimed to validate the hypothesized model, was reported and discussed in Chapter 5. The hypothesized model was supported. It was found that the online market characteristics and mediators incorporated in the model were critical for online consumer relationship building, and the relations among these constructs reveal important implications for etailers reviewing their RM strategy. Contributions and limitations of the research are presented in Chapter 6.

abstract: Doctor of Philosophy (PhD)


title: Unconditioning Postmodernity: Radical Acts of Resistance in Contemporary Texts

contributor:
King, James
English

subject:
English Language and Literature
contemporary texts
late-capitalistic culture

abstract: This dissertation investigates several contemporary texts I can subversive defamiliarizations in which charn.cters take extreme measures in order to exist outside of the hegemonic limits of late-capitalist culture. It is my assertion that these texts are different to previous representations of counter-cultural resistance in important ways, precisely because of the wildly unusual methods necessarily adopted by their characters to evade a culture that seems to have become increasingly perverse and pervasive. Chapter 1 contains an introductory definition of subversive defamiliarizations and the specific cultural milieu which they interrogate. Chapter 2 is a consideration of Chuck Palahniuk's novel Fight Club and David Fincher's t1lm adaptation, in which the anarchic protagonist instigates a broad range of extreme acts of resistance in an attempt to place himself ideologically outside of consumer culture. Chapter 3 discusses Irvine Welsh's Trainspotting and Danny Boyle's film version, which argue that the rules of modem existence have become so detrimental to the contemporary subject that even a potentially life threatening alternative lifestyle (heroin addiction) may be more rewarding. Chapter 4 examines Lars von Trier's Dogme95 film The Idiots, about a group of Danes who are united by the bizarre belief that "spassing," or pretending to be mentally retarded, constitutes a genuine critique ot~ and alternative to, late-capitalist life. Chapter 5 concludes this dissertation with a brief analysis of three novels--Chuck Palahniuk's Survivor and Bret Easton Ellis's Glamorama and American Psycho--subversive defamiliarizations that frame their critiques by presenting characters who completely immerse themselves in their culture's ideology. The critical function ofthese texts emerges because, in each case, an escalating surrender to, and absorption by, the dominant culture occurs simultaneously and causally with encroaching madness.

abstract: Doctor of Philosophy (PhD)


title: Model Studies on Biological Energy Conversion Mechanisms

contributor:
Bader, Richard F. W.
Chemistry

subject: Chemistry Chemistry

abstract:
This thesis is concerned with the design of ATP-producing physical and chemical model systems and the investigation of the mechanisms of ATP formation at the molecular level. The ultimate purpose of this study is to apply the concepts derived from these model systems to more complex biological systems. The mechanisms of energy transduction in living organisms may then be approached at a molecular level.

Based on the study of the model systems, three modes of activation during the ATP-forming chemical steps for either ADP or inorganic phosphate have been identified. They are:

(1) Through a one-electron reduction of ADP into a radical form;

(2) Through the creation of oxidizing agents with redox potentials sufficient to oxidize inorganic phosphate;

(3) Through an activation of phosphate by coordination to a reduced hemecomplex, followed by aerobic oxidation of the resultant phosphate-heme complex.

In biological systems, the first mode may involve utilization of a reducing power of an electron transport chain, of a reducing functional group such as thiol in the ATP synthetase. The second mode may involve PS II or generation of delta singlet oxygen by various energy transfer processes. The third mode may involve the coordination of inorganic phosphate to a cytochrome, such as cytochrome-a₃ in an cytochrome-c oxidase complex.

abstract: Doctor of Philosophy (PhD)