title: Quasi Two Dimensional Magnetic Properties of the Tri-Rutile Phases MTa₂O₆, M = V, Fe, Co, Ni

contributor:
Greedan, J.E.
Chemistry

subject: Chemistry Chemistry

abstract:
The structural and magnetic properties of the tri-rutile phases MTa₂O₆ (M = V, Fe, Co, Ni) were investigated. The nuclear and magnetic structures were refined from neutron powder diffraction data. The magnetic M²⁺ ions are located in planes perpendicular to the c axis. The distance between neighboring planes is approximately 4.5 Å. As a result, these compounds are quasi two dimensional magnetic systems, because the magnetic exchange interaction between ions in (001) planes is much larger than the interaction between ions in neighboring planes.

Evidence for important two dimensional correlations has been obtained from magnetic susceptibility and heat capacity measurements. The magnetic susceptibility of these materials is characterized by a broad maximum at a temperature substantially above the ordering temperature. The experimentally observed magnetic susceptibility was compared to the predictions for 2-d quadratic layer models. The exchange interaction was antiferromagnetic in all cases. NiTa₂O₆ and VTa₂O₆ are Heisenberg systems with S = 1 and S = 3/2, respectively. The magnetic susceptibility of CoTa₂O₆ was consistent with an S = 1/2 Heisenberg model, while FeTa₂O₆ showed Ising-like behavior with S = 11.2.

The magnetic structures of FeTa₂O₆ and VTa₂O₆ were determined. Mössbauer effect measurements were used to distinguish between two possible structural models for FeTa₂O₆. The magnetic moments of the Fe²⁺ ions points along <110> directions. The magnetic structure of VTa₂O₆ is similar, but the V²⁺ moments are oriented along <001>.

abstract: Doctor of Philosophy (PhD)


title: The Rape of Europa in Ancient Literature

contributor:
Murgatroyd, P.
Classics

subject: Classics Classics

abstract: This thesis considers how ancient authors narrate the story of Europa's rape in such a way as to "place their own mark" on the myth. In chapter one, I explore aspects of the Europa myth that often do not appear in the larger extent works such as Europa's function in religion, the archaeological representations of her rape, and the rationalization of the myth etc. Chapter two provides the audience with the basic outline of the story so that it will be equipped to appreciate the changes each writer makes to the story. As well, the development of the Europa myth over time is considered here. Outlined in chapter three is the approach (i.e. the use of traditional and new tools of literary criticism) I take to investigate the works offered by the ancient writers, beginning first with Moschus' account. An appreciation of the techniques Moschus incorporates is presented in chapter three while in chapter four the poet's elaboration of the ekphrasis and the inclusion of an embedded narrative are examined. The next three chapters (5, 6, and 7) look at Horace's and Ovid's (two) treatments of the rape of Europa, and chapter eight focusses on the versionf of later Greek writers, Achilles Tatius, Lucian and Nonnos. Finally, in chapter nine conclusions are made about the various rape narratives of Europa, especially about trends in the myth's treatments, links and contrasts between versions, and the variety which each writer adds with regard to form, description, tone and characterization. This investigation sheds new light on how ancient authors, when faced with a long tradition of myth telling, go about creating a fresh and entertaining story.

abstract: Doctor of Philosophy (PhD)


title: Array Geometry Effects on Vortex Shedding and Instability in Heat Exchanger Tube Bundles

contributor:
Weaver, D. S.
Mechanical Engineering

subject:
Mechanical Engineering
Mechanical Engineering

abstract: Eight tube arrays were tested to determine the effect of tube pattern and pitch on excitation phenomena in tube arrays in crossflow. These consisted of two different pitch-to-diameter ratios for each of the four standard heat exchanger tube array configurations. Measurements of vortex shedding frequencies showed that laminar vortex shedding may occur for some tube arrays at low Reynolds numbers and is associated with very high Strouhal numbers. Some arrays showed multiple values of Strouhal numbers at moderate Reynolds numbers, and over a small range of pitch ratios. Quite good agreement is found with some of the published results. Also, an improved correlation of the existing Strouhal numbers is obtained. The effect of tube pattern and pitch on the critical flow velocities at low damping parameter was determined. The results were used with other available results to determine the variation of the reduced velocity with the damping parameter for the different arrays tested.

abstract: Doctor of Philosophy (PhD)


title: Flexibility and Criticalness in Resource Use: The Case of Urban Expansion and Land Needs for Agriculture

contributor:
Smit, B.E.
Geography

subject: Geography Geography

abstract:
This thesis reviews the debate over the conversion of agricultural land to urban uses, and assesses the usefulness of land and land-use classification techniques for establishing land-use priorities. It demonstrates that the establishment of land-use priorities cannot be based solely on an assessment of the supply of land of different degrees of suitability for agriculture, and outlines the type of information needed for land-use planning. It argues that in order to determine if and where agricultural Iand needs to be protected to ensure adequate food production capacity, policy-makers require information on the capacity of the land base to meet agricultural commodity requirements under a variety of future conditions. This includes data not only on the feasibility of meeting given demands, but also on how much production capacity exists and whether the fulfillment of given demand hinges upon particular land areas or types of land being available to agriculture.

Flexibility is interpreted as the amount of production capacity that remains after specified demands are met. This thesis assesses several measures of flexibility. Each measure is based upon the analysis of a linear set of inequalities which describe resource availability and demand conditions. Two different approaches are examined. The first approach determines the extent to which production capacity exceeds or falls short of given demands. The second approach is based on the size of the feasible region defined by the linear set of inequalities.

Criticalness is interpreted as the extent to which the fulfillment of given demands is dependent upon different types of land being available to agriculture. The thesis has assessed several measures of land-use criticalness. Each of the criticalness measures is based on the analysis of a linear set of inequalities. Two types of measures are assessed. The first type rates the importance of assigning individual crops to each land type so as to meet given demands. This measure takes two forms: absolute minimum assignments and conditional minimum assignments. The second type rates the importance of each land type in meeting all the demands.

abstract: Doctor of Philosophy (PhD)


title: ADOLESCENT MOTHERS' SATISFACTION WITH POSTPARTUM NURSING CARE: QUANTITATIVE AND QUALITATIVE APPROACHES

contributor:
DiCenso, Alba
Nursing

subject: Nursing Nursing

abstract: The objective of this research was to investigate adolescent mothers' perceptions of the quality of their postpartum nursing care. The first of two studies was a matched cohort survey designed to compare unmarried adolescent and married adult mothers' satisfaction with their postpartum nursing care. Eighty adolescent/adult postpartum mother pairs were matched according to their parity, mode of delivery, infant health status, and infant feeding method. Although the two mother groups had similar health status, and received nursing care on the same postpartum unit during the same time period, adolescent mothers scored lower on the Newcastle Satisfaction with Nursing Scales (NSNS). Among the adolescents, post-cesarean section mothers were less satisfied than those who had delivered vaginally. Psychometric testing of the NSNS demonstrated its validity as a measure of postpartum patients' satisfaction with nursing care. The second study used a phenomenological approach to seek in-depth understanding of satisfactory and unsatisfactory nursing care from the perspective of adolescent mothers. Fourteen adolescent mothers recently discharged from one of four postpartum units were interviewed. Results indicate that adolescent mothers' satisfaction with nursing care is influenced by the interpersonal skills of nurses. Adolescent mothers' hesitancy to join in the interplay required to establish effective nurse-patient relationships places the initial responsibility of relationship development on the nurse. Adolescents expressd feeling 'at ease' with nurses and were encouraged to participate in relationship development when they perceived nursing care.

abstract: Doctor of Philosophy (PhD)


title: The Relation Among Vessel Injury, Thrombus Formation and Platelet Survival

contributor:
Kinlough-Rathbone, R.L.
Mustard, J.F.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
Shortened platelet survival observed in individuals with thromboembolic vascular disease could be due to platelet consumption or turnover in thrombi or platelet turnover on the damaged vessel wall. The object of this study was to examine the relationship between:

a) platelet consumption and exchange in thrombi and platelet survival

b) platelet accumulation and turnover on the injured vessel wall and platelet survival.

Indwelling catheters were inserted into rabbit aortae to induce repeated vessel injury and macroscopic chrombus formation. Radiolabelled platelets monitored platelet participation in thrombosis and platelet accumulation on the injured vessel wall. Morphological studies assessed the thrombus characteristics and the cellular events on the vessel wall.

During the first 24 hours following the insertion of indwelling aortic catheters, thrombi formed, attained their maximum size and maintained a constant weight thereafter. ⁵¹Cr-labelled platelet incorporation into thrombi following the growth, decreased by about 50% by 3 days. Loss of radioactivity from the thrombus during the time when thrombus weight remained constant indicated platelet lysis, phagocytosis or loss of whole platelets from the thrombus.

Both morphological studies and studies using platelets doubly labelled with ¹²⁵I and ⁵¹Cr demonstrated that some of the platelets initially incorporated into thrombi lysed. Studies of changes in platelet density as well as studies showing thrombi retained some capacity to accumulate circulating platelets indicated that platelets exchanged in thrombi and some of the platelets that had participated in thrombus formation returned to the circulation as less dense platelets.

The consumption and exchange of platelets in thrombi during the acute phase of growth correlated with maximal shortening of platelet survival time. When platelet survival studies were carried out 1 week after insertion of the catheter (at a time when thrombus growth had ceased and platelet accumulation into thrombi was decreased) platelet survival continued to be shortened. At this time, the extent of platelet accumulation on the injured vessel wall was similar to that observed at the time of insertion of the catheter suggesting platelet interaction with the injured vessel wall influenced platelet survival.

Studies using long and short catheters demonstrated that short catheters induced comparatively less vessel injury than long catheters but thrombus formation was significantly increased. Platelet survival studies carried out at 3 days after insertion of long or short catheters (when thrombus growth had ceased) indicated that the short catheters had no significant effect on platelet survival whereas long catheters continued to shorten platelet survival time.

In conclusion, extensive thrombus formation with evidence of platelet exchange in thrombi is associated with significant shortening of platelet survival time. However, this effect is detectable only during the acute phase of thrombus formation. In contrast, repeated vessel injury in association with continuing platelet turnover on the vessel wall can shorten platelet survival time.

Therefore, shortened platelet survival time is a manifestation of acute thrombus formation, repeated vessel injury or both.

abstract: Doctor of Philosophy (PhD)


title: THE MITOCHONDRIAL THEORY OF AGING IN HUMAN SKELETAL MUSCLE: EFFECTS OF RESISTANCE EXERCISE

contributor:
Tamopolsky, Marie. A.
Kinesiology

subject: Kinesiology Kinesiology

abstract: Introduction. The mitochondrial theory of aging proposes that a vicious cycle of events including an age-related increase in mitochondrial (mt) reactive oxygen species (ROS) cause damage to mtDNA, resulting in electron transport chain dysfunction (ETC). This, in turn, causes a loss in the ability to maintain cellular energy requirements and results in a further increase in ROS production. Based on several reports of normal ETC activity in skeletal muscle of older adults, there is some question as to whether or not the mitochondrial theory is applicable to skeletal muscle. Resistance exercise (RE) is an efficacious therapy for increasing strength and muscle mass. RE training results in a recovery of strength and muscle fiber cross-sectional area in older adults. As such, resistance exercise should slow or reverse the underlying mechanisms associated with skeletal muscle aging. We conducted a series of experiments to: 1) examine the mitochondrial theory of aging in human skeletal muscle; and 2) examine the effects of RE on variables associated with the mitochondrial theory of aging. We hypothesized that aging would be associated with several aspects of the mitochondrial theory of aging such as an increase in oxidative stress, an alteration in antioxidant capacity, an increase in mtDNA deletions, and a reduction in ETC enzyme activity. Furthermore, we hypothesized that regular RE training would result in an increase in antioxidant enzyme activity, a reduction in oxidative damage to proteins and DNA, and reduction in mtDNA deletions. Methods. Muscle biopsy specimens and urine samples were collected from young and old men, and subsequently analyzed. An initial study examined the effects of aging on mtDNA deletions, oxidative damage to proteins and DNA, antioxidant enzyme activity, and oxidative enzyme activity. Two subsequent studies examined the impact of resistance exercise training on the same variables mentioned above. Results. 1. Oxidative damage to protein and DNA was higher in older vs. younger men. Antioxidant enzyme activity, in particular MnSOD and catalase were higher in old as compared to young. Oxidative enzyme activity was not lower as a function of age. In fact, complex I+III activity was higher in older as compared to younger men. There was a reduction in full-length mtDNA, and the appearance of mtDNA deletions associated with aging. 2. Whole-body RE training for 14 weeks resulted in a decrease in oxidative damage to DNA in older men. Catalase, CuZnSOD, and MnSOD protein content were unchanged, however, mtCK protein content was higher after training. Oxidative enzyme activity was unchanged with the exception of complex N, which demonstrated a specific up-regulation in response to RE training. RE had no effect on full-length mtDNA or mtDNA deletions 3. Unilateral resistance training (12 weeks) had no effect on oxidative damage to protein. Antioxidant enzyme activity, in particular CuZnSOD, and catalase was up-regulated following resistance exercise training. There was no change in oxidative enzyme activity or protein content. Full-length mtDNA was unchanged, and there was no effect of resistance exercise on mtDNA deletions. Conclusion. Aging was associated with an increase in oxidative stress, mtDNA deletions, and significant changes in antioxidant enzymes, suggesting that aspects of the mitochondrial theory of aging were applicable to skeletal muscle. Regular RE training resulted in a decrease in oxidative damage to DNA, and was sufficient to cause a further up-regulation of antioxidant enzyme activity, beyond that induced by aging. Finally, complex IV of the ETC may have indirect antioxidant properties by improving ETC efficiency.

abstract: Doctor of Philosophy (PhD)


title: Advances in Wideband Array Signal Processing Using Numerical Bayesian Methods

contributor:
Reilly, James P.
Kirubarajan, Thia
Electrical and Computer Engineering

subject:
Electrical and Computer Engineering
Electrical and Computer Engineering

abstract: This thesis focuses on joint model order detection and estimation of the parameters of interest, with applications to narrowband and wideband array signal processing in both off-line and on-line contexts. A novel data model that is capable of handling both narrowband and wideband cases with the use of an interpolation function and signal samples is proposed. In the off-line mode, Markov Chain Monte Carlo methods are applied to obtain a numerical approximation of the joint posterior distribution of the parameters under the condition that they have stationary distribution functions. On the other hand, if the distribution functions are nonstationary, the on-line approach is used. That approach employs a sequential implementation of Monte Carlo methods, applied to probabilistic dynamic systems. Four inter-related problems were addressed in the course of this thesis. 1. A new data structure based on interpolation functions and signal samples to approximate wideband signals was developed. This data model, after appropriate transformation, has similar features found in the conventional narrowband data model. Furthermore, as the novel data model is developed for the wideband scenario, it can also address the narrowband scenario without change of structure or parameters. This novel data model is the basis on which the MCMC and the SMC approaches solve the array signal processing problems developed in the subsequent chapters. 2. The first algorithm presents an advanced approach using sequential MC methods to beamforming for narrowband signals in white noise with unknown variance. Traditionally, beamforming techniques assume that the number of sources is given and the signal of interest (or target) is stationary within an observation period. However, in reality these two assumptions are commonly violated. The former assumption can be dealt with by jointly estimating the number of sources, whereas the latter severely limits the usefulness of conventional beamforming techniques when the target is indeed moving. In the case where the sources are moving, tracking the incident angles of the sources are required, and the accuracy of such tracking significantly affects the performance of signal separation and recovery, which is the objective of beamforming. The proposed method is capable of recursively estimating the time-varying number of sources as well as incident angles of the sources as new data arrive such that the signal amplitudes can be separated and restored in an on-line fashion. 3. The second algorithm presents an application of MCMC methods for the joint detection and estimation problem for the wideband scenario in white noise with unknown variance. In general, compared to the narrowband scenario, it is more difficult and cumbersome to solve this array signal processing problem in the wideband context. Conventional approaches tend to solve this problem in the frequency domain, and as such require a considerable amount of data to sustain accuracy, which imposes a large computational burden for these approaches. Furthermore, these approaches employ separate algorithms like AIC and MDL to estimate the number of sources. In contrast, the proposed method utilizes the reversible jump MCMC technique that simultaneously detects the number of sources and estimates the parameter of interest within the same algorithm. The proposed method is applied to the novel data model mentioned earlier and solves the problem in the time domain, which significantly reduces the requirement for a large number of data samples. 4. The final algorithm is an extension of the off-line approach to wideband array signal processing problem using sequential MC methods. Most conventional array signal processing approaches are developed under the assumption that the sources are stationary in direction of arrival. If this assumption is invalid, the solutions from these approaches become suboptimal and their performance is significantly degraded. When sources are nonstationary, tracking the motions of the sources is needed, but in wideband scenarios the same problem becomes more difficult and cumbersome than in narrowband scenario because the methods for wideband scenarios usually require a considerable amount of data for processing. The proposed algorithm focuses on the sequential implementation of particle filters for probabilistic dynamic systems. This algorithm is applied to the modified novel data structure mentioned earlier in white noise with unknown variance for recursive estimation of the motions of the sources as new data arrive. A systematic statistical testing procedure is used to keep track of the number of sources.

abstract: Doctor of Philosophy (PhD)


title: Exploring Experiences of Romantic Relationships and Intimacy for Women with Anorexia Nervosa

contributor:
Boblin, Sheryl
Nursing

subject: Nursing Nursing

abstract: Intimacy is considered an essential aspect of 'ideal' marriages and romantic relationships. Western culture in particular, encourages individuals to seek intimacy within their romantic relationships and maintain it through consistent effort. Intimacy as an area of inquiry in romantic relationships has remained largely unexamined for women with anorexia nervosa (AN) despite a growing body of quantitative research signifying deficiencies in their romantic relationships as compared to women without the disorder. With this in mind, this dissertation sought to describe experiences with romantic relationships and intimacy for women with AN through phenomenological inquiry. A purposive sample of 11 women participated through in-depth, semi-structured interviews. Analysis revealed that these women engaged in diverse relational experiences characterized by dialectical themes of engagement and distancing, which acted as basic drivers of relational change and maintenance. For many women, their desired level of intimacy exceeded what was present in their relationships, with intimacy precluded by incongruent disclosure with their partner and the women's lack of physical desire. Collectively, these findings demonstrate that the women's relational experiences did not contradict generalized theories. Rather, like other individuals in relationships, the participants' relationships involved behavioural patterns, motivational dynamics, and situational environments in the context of their lives, which in their situation happened to include an eating disorder. This study suggests that understanding relationships for women with AN should not be limited to a disease framework, but should be explored within a normativee relational framework. Within this perspective health care professionals can tailor interventions specific to patient ways of relating.

abstract: Doctor of Philosophy (PhD)


title: "And I make it real by putting it into words:" Masochism in the modern British Novel."

contributor:
Adamson, Joseph
English

subject:
English Language and Literature
English Language and Literature

abstract: Using the psychopathological literary methodologies of trauma theory and shame psychology, this dissertation addresses the subject of masochism in the modem British novel. Literary psychopathologists investigate the meaning of fragmented narratives by comparing their symbology and mythoi to psychiatric models of trauma, masochism and shame. Trauma theory, for example, focuses on an individual's proto-experience and her/his need to express it in language, while shame theory provides a helpful framework for explaining manifestations of overbearing shame. The nucleus of my thesis on non-Freudian masochism is pointedly heuristic: it aims to demonstrate to the reader a methodology that is capable of interpreting British modernist texts with a deeper psychological understanding than is offered by most Freudian methodologies. Non-Freudian masochism theory specifically involves the need to hurt oneself or punish oneself by defeating or subverting oneself out of shame or guilt. Even though its paradoxical teleology is rooted in the attainment oflove and respect, its unique affective signature resides in its myopic solicitation of self-destructively fatal, when not mortifying, social situations. Whereas my introduction focuses on the conceptual proximity of trauma and shame affect to my own hermeneutical non-Freudian interpretation of masochism, the subject of my conclusion is the performativity of bearing witness, and the empathic ethos of testimonials of departure. My methodology is left pregnant with the hope that my future will include more opportunities to interpret further works by Henry James, Joseph Conrad, E. M. Forster, D. H. Lawrence and Virginia Woolf, as well as other masters of the literary canon.

abstract: Doctor of Philosophy (PhD)


title: Hormonal Regulation of Myometrial Gap Junctions: Control by Estrogen, Progesterone and Prostaglandins

contributor:
Garfield, Robert E.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
The muscle of the pregnant uterus transforms into an active and reactive tissue at term which is necessary for expulsion of the fetus and termination of pregnancy. Gap junctions develop between the smooth muscle cells of the uterus immediately prior to term and disappear after delivery. Gap junctions may be providing the structural basis for improved communication between myometrial cells during labor thereby leading to the synchronized coordinated muscle activity required for effective labor. Although gap junctions appear to have significant implications in the termination of pregnancy, the regulation of their presence in the myometrium is not completely understood but may depend upon hormonal changes that occur prior to parturition.

In the studies reported in this thesis, quantitative thin section electron microscopy showed that high doses of estradiol stimulated, whereas progesterone when administered with estradiol, suppressed the presence of myometrial gap junctions in non-pregnant animals. The steroid hormones regulate the presence of gap junctions by controlling the synthesis of the junction proteins probably through their receptor mechanism. In addition, high doses of estradiol may selectively stimulate the synthesis of a prostaglandin which may be required for the development of gap junctions. Prostaglandins appear to be involved in junction regulation since inhibitors of cyclo-oxygenase potentiated estradiol stimulation of gap junctions. Moreover, treatment of pregnant animals with estradiol resulted in the presence of numerous myometrial gap junctions and abortion. These results demonstrate that the steroid hormones and prostaglandins regulate the presence of myometrial gap junctions and that their presence in the myometrium may be a requirement for the occurrence of term as well as preterm labor.

Cell-to-cell communication via gap junctions is also believed to be involved in the control of cellular and tissue growth. The myometrium grows dramatically throughout pregnancy to accommodate the growing fetus. Moreover, the steroid hormones, in particular estradiol, stimulates growth of the uterus and prostaglandins also appear to be involved in the process. Since the hormones and prostaglandins regulate uterine growth and the presence of myometrial gap junctions (see above), the relationship between the two events was further evaluated in this thesis. Studies on non-pregnant animals after various hormonal treatments and in untreated pregnant animals demonstrated that regulation of uterine growth (of which the myometrium is a major component) and the presence of gap junctions in the myometrium are dependent upon the hormonal environment. The results suggest a complex interaction between the steroid hormones, a product of the cyclo-oxygenase and/or lipoxygenase pathway for control of gap junctions and myometrial growth. Myometrial growth may occur because of the lack of gap junctions but the cessation of growth of this tissue does not depend on the presence of the junctions. The development and presence of gap junctions, however, may be partially dependent upon myometrial growth.

abstract: Doctor of Philosophy (PhD)


title: Blind Signal Separation

contributor:
Luo, Zhi-Quan (Tom)
Electrical and Computer Engineering

abstract: This thesis addresses the blind signal separation (BSS) problem. The essence of the BSS problem is to recover a set of source signals from a group of sensor observations. These observations can be modeled as instantaneous or convolutive mixtures of the sources. Accordingly, the BSS problem is known as blind separation of instantaneously mixed signals or blind separation of convolutively mixed signals. In this thesis, we tackle both problems. For blind separation of instantaneously mixed signals, we first cast the separation problem as an optimization problem using mutual information based criterion, and solve it with an extended Newton's method on the Stiefel manifold. Then, for a special case in which the sources are constant modulus (CM) signals, we formulate the separation problem a constrained minimization problem utilizing the constant modulus property of the signal. Again, we solve it using the Newton's method on the Stiefel manifold. For the problem of blind separation of convolutively mixed signals, which is also known as blind deconvolution problem, we first propose a time domain method. We cast the separation problem as an optimization problem using a mutual information based criterion and solve it using a sequential quadratic programming (SQP) method. Then, we propose a set of higher-order statistics (HOS) based criteria for blind deconvolution. We also discuss the relationship of our proposed criteria and other HOS based criteria. We then propose a frequency domain HOS based blind channel identification approach. In this approach, we identify the channel frequency response by jointly diagonalizing a set of so called polyspectrnm matrices. Finally, we propose a second-order statistics (SOS) based method for blind channel identification. Assuming the channel inputs are cyclostationary signals, we identify the channel frequency response through the singular value decomposition (SVD) of a cyclic cross-spectrum based matrix. Numerical simulations are used throughout this thesis to compare our proposed methods with other methods from the literature and to demonstrate the validity and competitiveness of our proposed methods.

abstract: Doctor of Philosophy (PhD)


title: Multi-component Defect Model for Semiconductor Lasers

contributor:
Cassidy, D.T.
Engineering Physics

subject:
Engineering Physics
Engineering Physics

abstract: A multi-component defect model for degradation in semiconductor lasers is derived, discussed, and compared to experimental data and other existing degradation models for semiconductor lasers. The degradation model was designed to describe the change of threshold current as a function of aging time and is based on a population growth model in which only limited resources for the creation or growth of defects exist. Besides degradation, defect-annealing effect is incorporated into the multi-component model to examine high-power lasers that exhibit an annealing effect. A compatible lifetime estimation scheme is derived, discussed, and compared to the Hartman-Dixon method [Appl. Phys. Lett. 26, 239 (1975)] for lifetime estimation. Photoluminescence topography was utilized to probe the surface stability of semiconductor lasers during aging. A degradation of photoluminescence yield was observed at the active region. The degradation signifies an increase of surface recombination velocity. However, the reflectance of the surface is not modified by the aging-induced photoluminescence degradation.

abstract: Doctor of Philosophy (PhD)


title: Pressure-Lung Volume Relationship and Electromyography of Inspiratory Muscles in Man during Partial Curarization

contributor:
Pengelly, L.D.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
Saunders and his associates reported that during submaximal neuromuscular blockade, vital capacity was reduced to a greater extent than would have been predicted according to the reduction in the maximal inspiratory pressure in a simple in a simple mechanical model (J. Appl. Physiol. 44:589,1978). Disproportionate respiratory muscle weakness and a different recruitment pattern for different voluntary efforts were proposed as possible explanations.

This issue was addressed by measuring the rectified electromyogram of the diaphragm, intercostal, scalenes, and sternomastoid muscles during maximal and submaximal static inspiratory manoeuvres. Two studies were performed. The control series of experiments showed that at very low levels of static pressure, only the diaphragm was activated. Further increases in pressure then recruited the intercostal/accessory muscles, in some subjects more than in others. There was generally an orderly increase in the rectified EMG in all muscles with elevations in pressure. For particular levels of pressure to be produced at lung volumes above the relaxed end-expiratory position, the EMG was increased. Compared to the maximum EMG elicited with maximal static pressures or full inspirations, resting ventilatory requirements still leave a large myo-electric reserve.

In the submaximal neuromuscular block study, the mean maximal inspiratory pressure was decreased from 103 to 39 cm H20, but only two of the five subjects behaved in the manner observed by Saunders and his associates. There was no clear evidence that the diaphragm was less affected than the other muscles. In many cases however, a submaximal level of pressure was achieved by augmented EMG in all muscles. It is suggested that curare interferes with the conversion of electrical events into whole muscle tension and/or that the impaired chest wall volume compartments are inefficient at producing static pressure.

abstract: Doctor of Philosophy (PhD)


title: Measuring the Perceived Relation Between Jobs and Salaries Using Relative Judgment Theory

contributor:
Link, S.W.
Psychology

subject: Psychology Psychology

abstract: Thurstone's law of comparative judgment and a recent extension of his model, relative judgment theory were employed separately in two experiments to obtain scale values for a number of occupations. While Thurstone's theory uses only the probability of the subjects' judgments, relative judgment theory, which is based on a sequential random walk process provides further predictions concerning the latency probability function. In making judgments, a subject tends to take more time to respond when the value of the stimulus is close to a mental referent which the subject has adopted. The random walk model gives scale values in good agreement with the previous Thurstonian techniques. In addition, the fit of the data to the model for the predicted linear relationship between a function of response probability and response time was very close.

abstract: Master of Arts (MA)


title: Characterization of the Role of Herpes Simplex Virus protein VP 16 in Viral Gene Expression through Interactions with the Virion Host Shutoff protein (vhs) and HCF-1

contributor:
Capone, John P.
Biochemistry

subject: Biochemistry Biochemistry

abstract: Herpes Simplex Virus 1 (HSV1) VP16 transcriptionally activates viral immediate-early (IE) genes, through the formation of a multi-protein structure termed the VP16-induced complex (VIC). VIC is comprised of cellular transcription factors Oct -1 and HCF-l. In addition, VP 16 is a pre-formed, structural protein that has a critical role in virion assembly. At least one aspect of its role at late times post-infection includes the downregulation of the virion host shutoff protein (vhs); which functions to indiscriminately degrade mRNA. The interaction between VP 16 and vhs was characterized within this thesis in order to differentiate it from the regions involved in VIC assembly, as well as to investigate its functional importance within HSV 1. Refined mutagenesis studies were used to localize a minimal binding domain within VP16; in which the alteration a single residue was sufficient to abrogate binding to vhs. Our results indicate that the interaction between VP16 and vhs could effectively be uncoupled from VIC assembly and the transactivation of IE genes. Moreover, virus complementation assays were used to demonstrate that the interaction with vhs is specifically required to sustain virus growth. We were also interested in characterizing VP16 transactivation. Previous work within our laboratory had determined that the amino-terminal domain of VP16, excluding itspotent acidic activation domain (AAD), possessed an activation phenotype in yeast and mammalian cells. To investigate these findings further, mutagenesis experiments were employed to differentiate between the activity in mammalian and yeast cells. HCF-l, a recently identified transcriptional co-regulatory protein, was identified as a co-activator of the truncated VP 16 in mammalian cells. HCF-l was also capable of synergizing VP 16 in the activation of an IE gene construct. These findings identify a novel role for HCF-l in HSV 1 gene expression. Taken together, this work enhances our understanding of the role of VP 16 in viral gene expression and pathogenesis.

abstract: Doctor of Philosophy (PhD)


title: AN INTENSIFIED PRAGMATISM IN REPSONSE TO REPRODUCTIVE EXPERIENCES AND MEDICALIZATION: A CASE STUDY OF CAPE BRETON WOMEN

contributor:
Miall, Charlene
Sociology

subject: Sociology Sociology

abstract: This dissertation focuses on the reproductive experiences of Cape Breton women. Using feminism and symbolic interactionism, I explore these experiences by conducting focus group and semi-structured individual interviews with 47 women from the Cape Breton Regional Municipality. Three major themes emerged from the women's stories. First, women assess their situations and make decisions to maximize their advantages. Second is what I characterize as women's "intensified" pragmatism engendered by their complex socio-cultural environment. Problems of high unemployment, severe pollution and difficult access to health care have contributed to a culture that encourages individuals to expect the worst and to trust only those closest to them. In relation to women's reproductive experiences, this translates into distrust of medical professionals, great reliance on other women, and culturally influenced understandings of normal reproductive processes. Third, the advantages women identify for using medical interventions and treatments are subjective, arising out of lived experiences. For those not privy to the women's experiences or those operating from a biomedical position, these advantages may seem counter-productive or paradoxical. Considering the three themes as related parts of a whole, I found the difficulties and disadvantages associated with life in Cape Breton resulted in a strengthening of women's agency. Given the constraints on access to health care and the social problems, these women had no choice but to improvise and be pragmatic. Theoretically, this research reaffirms the need to pull together the literature focusing on structural constraints and lay perspectives to understand the role of medicalization in women's lives. It also illustrates that control is an important issue not just in women's interactions with medical professionals, but also in interactions between women. Substantively, this work contributes to our understanding of women's pragmatism, the importance of the context in which it operates, and how these impact on women's definitions of normal reproductive experiences.

abstract: Doctor of Philosophy (PhD)


title: GENERATION OF IMMUNE RESPONSES IN EXPERIMENTAL ALLERGIC AIRWAY INFLAMMATION

contributor:
Jordana, Manel
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: Allergic diseases, including asthma, result from airway inflammatory responses directed against ubiquitous antigens-allergens. The detailed immunological mechanisms underlying the development of allergy (allergic sensitization) have not been fully elucidated. Our understanding of the complexity of cellular interactions underlying allergic inflammation originates mainly, but not exclusively, from studies in experimental animal models. The studies presented in this thesis utilize experimental mouse models of anti-geninduced allergic airways inflammation in order to investigate 1) the events occurring during sensitization (primary immune responses) and following re-challenge (secondary immune responses) in two immunologically important sites: lungs and lymph nodes following experimental allergen (ovalbumin; OVA) exposure; 2) the role of the secondary lymphoid organs vs. lungs in elicitation of immune responses to allergen; 3) the importance of two major costimulatory pathways - CD28/B7 and ICOS/B7RP-1 - in the generation of allergic airways inflammation. Findings presented here indicate that introduction of antigen leads to vigorous T and B cell activation in the draining lymph nodes. Such activation translates into the acquisition of a Th2 phenotype, an important step in the generation of allergic sensitization. Considering the multitude of changes occurring in the draining lymph nodes, the importance of lymph nodes during sensitization was investigated in mice devoid of lymph nodes - Iymphotoxin (l deficient mice. The study demonstrated the absolute requirement of lymphoid organs, either lymph nodes or spleen in generating of Th2-type inflammatory responses. Finally, studies on CD28 and B7RP-1 deficient mice indicated that, whereas the CD28/B7 pathway is necessary for the establishment of allergic airway inflammation, the ICOSIB7RP-1 pathway is redundant. The data presented in this thesis identifies several important aspects by which the immune system generates efficient allergic airway inflammation. As we suspect that new-sensitization occurs after each exposure to allergens. information in this thesis may provide insights into novel therapeutic strategies.

abstract: Doctor of Philosophy (PhD)


title: Aging and Human Neuromuscular Function

contributor:
McComas, Alan J.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
In view of the importance of maintaining normal mobility in the aging population, the function of two opposing groups of leg muscles, the ankle dorsiflexors and plantarflexors, was studied in a sample of 111 healthy men and women aged 20 to 100 yr. Three major questions were asked in this investigation: (1) To what extent does muscle strength decline with age? (2) Can descending motor pathways be optimally utilized by the elderly for activating lower motor neurons? (3) Does the time-course of muscle contraction become prolonged with age?

Summarized results were:

1. Maximal voluntary isometric strength (MVC) of the dorsiflexor and plantarflexor muscles showed a general pattern of decreased values after the fifth decade in both sexes. A similar decline of approximately 13% per decade was observed in the two muscle groups. As the plantarflexor muscles produced 4 times more torque than the dorsiflexor muscles in young adults, the absolute loss of strength was much greater for plantarflexor MVC.

2. The majority of subjects at all ages were able to utilize their descending motor pathways optimally for full muscle activation.

3. Contraction time and one-half relaxation time of the isometric twitch were prolonged with increased age in both muscles.

4. An additional observation was that flexibility of the ankle joint was reduced with increased age, although considerable rotation of the ankle was still possible in the oldest subjects.

Evidence from analysis of the compound muscle action potentials, peak twitch torques and muscle cross-sectional areas supported the conclusion that the decrease in strength with aging was due to a loss of excitable muscle mass. It was hypothesized that fat and connective tissue replaced muscle in the elderly. The findings of this study add to our knowledge about the aging process and its influence on neuromuscular function. It is also anticipated the results will be useful in geriatric clinics and for planning programs aimed at the prevention and rehabilitation of neuromuscular disability in the elderly population.

abstract: Doctor of Philosophy (PhD)


title: Mercury Mass Balance and Uptake by Fish in Acid Lake Ecosystems

contributor:
Kramer, J. R.
Geology

subject: Geology Geology

abstract:
The phenomenon of increasing the mercury body burdens of fish, on a lake to lake basis with decreasing pH₁ is found to exist. Although the interactions between fish, the ecosystem, water chemistry and other variables are extremely complex a simple conceptual solution is established to explain why mercury uptake by fish increases with decreasing pH.

A study on mercury in an acid lake watershed ecosystem (near Espanola, Ontario) was done as a precursor exercise. Mercury concentrations of various ecosystem compartments are within the ranges of values found by other workers for other systems. All values found are considered background or below background. For this type of lake-watershed system, the main mercury repository is the watershed soils and overburden materials. The main mercury fluxes are from the atmosphere to the soils and from the soils, via streams and groundwater, to the lake. The net result is that the watershed is being depleted in mercury at the rate of about 30 μg m⁻² yr⁻¹. This mercury is apparently ending up in the lake water, seston or sediments.

According to well established thermodynamic equilibria, pH, together with pCI, govern the speciation of inorganic mercury in freshwater inorganic systems. Under certain specific conditions of pH and pCI, the non-toxic mercury species Hg(OH)₂° exists, while under other conditions, most notably depressed pH, the biologically mobile and easily methylated HgCI₂° exists. It is shown here that lakes whose pH and pCl are such that the dominant mercury species will exist as HgCl₂° contain fish with higher mercury concentrations than lakes whose dominant mercury species exists in the form Hg(OH)₂°. This suggests that the more HgCI₂° that is available, the more mercury will either be methylated and taken up by fish, or taken up directly, and probably methylated in vivo.

abstract: Doctor of Philosophy (PhD)


title: Educational Promises and Efficiency Ideals: The Development of Management Education in Ontario, 1900 - 1960

contributor:
Cuneo, C.J.
Sociology

subject: Sociology Sociology

abstract: This study examines the concurrent development of business administration education and management theory and practice in Ontario. Management practice was developed in response to a particular set of needs perceived by those searching to establish stability and efficiency at the historically most explosive and highly vulnerable sphere of contention--the workplace. Behavioural science and management techniques are studied as social processes ultimately reflecting the dynamics and parameters of the social order. The main thesis of this study is that management practice and the training of management practitioners at the business schools worked to reinforce the belief that labour and other social problems are solvable within the parameters of the present social system. This belief was strengthened by the positivism of the engineers, behavioural scientists, and sociologists studying techniques of the managerial discipline. As part of the university curriculum, management theory was eventually afforded the respectability of any academic discipline. As a science, management strengthened the business curriculum and justified the purpose of business education in the academic environment. This work studies the curricula of four business departments at the Universities of Toronto, McMaster, Queen's, and Western Ontario over a sixty year period from 1900 to 1960. In particular the work examines published course descriptions and the content of a sample of textbooks in order to trace the introduction of management theories into the curricula of the schools of business administration. Scientific management and its introduction into the curriculum, the alteration of scientific management using the "softer" human relations technique, and the introduction of the theory of organizations to justify the authority structure, hierarchical relations, and the necessity of strong leadership are specifically examined. The work also considers the role played by key participants in the Canadian management movement and the involvement of Canadian businessmen and industrialists in the development of business and management curriculum. In general, a number of questions are posed regarding the emergence of management practice and the contribution of management practice and the business curriculum to the maintenance of stability, harmony, and efficiency within the social order.

abstract: Doctor of Philosophy (PhD)


title: DIE BONDING OF DIODE LASERS

subject:
Engineering Physics
Engineering Physics

abstract: An examination of the die bonding of semiconductor diode lasers is presented. The effects of changing a number of bonding parameters such as reflow time, reflow temperature, and cooling rate on InP-based diode laser chips are investigated. Lasers bonded with both preform solder and pre-deposited solder are explored. It is also observed that stress relaxation occus in die bonds of diode lasers after a time period of hundreds of hours. A finite element method model that iteratively fits to degree of polarization of photoluminescence data is presented. It is shown how this model is used to determine components of stress and strain owing to die bonding at the facet of diode lasers. The model is shown to be capable of helping to characterize die bonds. The effect of die bonding induced strain on the spectra of distributed feedback diode lasers is also investigated. Bonding strain effects the in situ grating in distributed feedback lasers which manifests as changes in the modes of the output spectrum and the stopband width. As well, it is observed that the lasting mode can flop from one side of the stopband to the other upon bonding and this effect is successfully modelled using a DFB laser model.

abstract: Doctor of Philosophy (PhD)


title: Associative Interactions Between Septo-Dentate and Perforant Path Afferents to the Rat Dentate Gyrus

contributor:
Racine, R.J.
Psychology

subject: Psychology Psychology

abstract:
Cooperative interactions between the septal (septo-dentate; SD) and perforant path (PP) inputs to the dentate gyrus granule cells (GCs) of the rat were examined to determine the effect on long-term potentiation (LTP). Tetanization of SD afferents produced LTP of the SD-GC response but not of the PP-GC response, and PP tetanization produced LTP of the PP-GC response but had no effect on SD-GC responses. Despite this specificity, concurrent SD and PP tetanization produced significantly greater LTP of the PP-GC population spike than was produced following PP-only trains. In addition to increasing its magnitude, concurrent trains also increased the duration of LTP. Concurrent SD and PP tetanization had no additional effect on SD-GC responses.

The heterosynaptic cooperativity effect depended on both the temporal interval between application of the SD and PP trains and on their order of activation. When the SD trains were applied less than 100 ms prior to the PP trains there was a large additional increment in LTP magnitude. Intertrain intervals between 100 and 1000 ms produced significantly smaller increments. Beyond 1000 ms, no interaction effects were observed. If the PP trains preceded the SD trains there was little or no evidence of a cooperativity effect. The PP-SD sequence actually appeared to inhibit the appearance of a cooperativity effect when the trains were subsequently applied concurrently.

Paired-pulse tests, designed to examine the effect of the SD trains on recurrent inhibition, raised the possibility that the SD trains may reduce the strength of the GC's recurrent inhibitory circuits and thereby increase the postsynaptic effect of each PP train.

These results increase the attractiveness of the LTP phenomenon as a candidate neural mechanism for learning and memory. The possible role of the heterosynaptic interactions in classical conditioning were discussed.

abstract: Doctor of Philosophy (PhD)


title: Artificial Intelligence Techniques Applied to Fault Detection Systems

contributor:
Poehlman, W.F.S.
Electrical and Computer Engineering

abstract: This thesis presents novel applications of Artificial Intelligence-based on algorithms to Failure Detection Systems. It shows the benefits intelligent, adaptive blocks can provide along with potential pitfalls. A new fault detection structure is introduced which has desirable properties when dealing with missing data, or data corrupted by extraneous disturbances. A classical alarm generation procedure is extended by transformation into an optimum, real-time, adaptive block. Two techniques, artificial Neural Networks, and Partial Least Squares, complement each other in one of the failure detection applications exploiting their respective non-linear and de-correlation strengths. Artificial Intelligence techniques are compared side by side with classical approaches and the results are analyzed. Three practical examples are examined: The Static Security Assessment of Electric Power Systems, the Oil Leak Detection in Underground Power Cables, and the Stator Overheating Detector. These case studies are demonstrated since each one represents a class of failure detection problems. The Static Security Assessment of Electric Power Systems in a class of problems with inputs which are somewhat correlated, and which has very little learning data. While the time required for the system to learn is not a concern, the recall time must be short, providing for real-time performance. The Oil Leak Detection in Underground Power Cables represents the class of problems where one has vast amounts of data indicative of a properly functioning system, however data from a failed system are very sparse. Unlike the Static Security Assessment problem, the oil leak detector has to consider the time dynamics of the system. Special provisions must be made to accommodate missing data which would interrupt contiguous data sets required for proper operation. This case study shows ways to exploit the slight sensor redundancy in order to detect sensor breakdown along with the detection of the main system failure. A third class of problems is showcased by the Electric Generator Stator Overheating detector. This application must deal with highly correlated inputs, along with the lack of fault data to be used for learning. Physical system non-linearities as well as time dynamics must also be addressed.

abstract: Doctor of Philosophy (PhD)


title: The Distribution of Gold and Other Elements in the Uranium Conglomerates of Elliot Lake, Canada

contributor:
Crocket, J.H.
Geology

subject: Geology Geology

abstract:
A study has been undertaken to investigate the controls on the concentration and distribution of gold and platinum group elements in the uranium deposits of Elliot Lake.

Gold is present almost entirely in the pyrite and gold concentration in the ore varies with pyrite content. Sporadic high gold values can be related to specific sedimentary structures and may indicate the presence of original detrital gold. Gold is preferentially concentrated in pyrite compared to pyrrhotite. The distribution of gold in pyrite along the strike of the Lower Reef, Denison Mine, is difficult to explain by the placer hypothesis. It indicates that the pyrite now observed in the oligomictic conglomerates is not of direct detrital origin.

An attempt to determine the concentration and distribution of platinum group elements within the ore conglomerates failed due to experimental problems.

The distribution of the majority of major and trace elements can be related to the mineralogy of the ore reefs. Relationships with pebble size are due in part to depositional processes operating at the time the conglomerates were deposited, and possibly in part to processes operating after burial of the conglomerates.

abstract: Master of Science (MS)


title: DEVELOPMENT OF A GEOMETRIC MODELLING APPROACH FOR HUMAN BODY SEGMENT INERTIAL PARAMETER ESTIMATION

contributor:
Dowling, James J.
Kinesiology

subject: Kinesiology Kinesiology

abstract: Calculating net joint forces and moments of force in the study of human movement requires accurate human body segment parameter (BSP) information. The purpose of this study was to investigate an approach for developing geometric models based on segment mass distribution (MD) information for BSP estimation. Study 1 investigated the MD properties of the human thigh for four human populations using dual energy x-ray absorptiometry (DEXA). Thigh mass, centre of mass in the longitudinal (CMx) and mediolateral (CMy) directions, and moment of inertia about the CM along an anteroposterior axis (IcMz) were determined using DEXA. Thigh MD properties of 20 subjects were used for model generation and the equations were validated on 80 subjects by comparing estimations with DEXA measurements. BSP estimations from 4 other models available in the literature were also examined. Study 2 followed the methodology of Study 1, using the forearm segment. Study 3 advanced on Studies 1 and 2 by adding a sagittal plane dimension to a lower leg model. Forty subjects underwent frontal and sagittal plane DEXA scans and models were validated using a split-half reliability method. The results of all three studies showed that mass and IcM estimates were not significantly better than the other models examined, however CM estimations were often improved. The models in Studies 1 and 2 may have been limited by the 2D nature of the methodology. The use of an elliptical model helped to account for the more posterior location of the CM in the lower leg, however insufficient statistical power may have prevented the detection of significant differences in mass and Icm estimates. The results of this study show promise for future modelling of human body segments. Modeling according to MD properties allows the assumption of constant density while accounting for inertial changes along the segment length. 3D model validation, greater sample sizes, and "the analysis of the remaining segments of the human body may lead us closer to understanding the kinetics of human movement.

abstract: Doctor of Philosophy (PhD)


title: Radiative Heat Transfer in Fibre Insulations

contributor:
Timusk, T.
Physics

subject: Physics Physics

abstract:
A first principles method of calculating combined radiative and conductive heat flow in fibrous insulation is presented. Using the measured complex refractive index for the bulk material, the scattering and absorption cross-sections are calculated for an isolated cylinder from expressions analogous to those of Mie theory for spheres. An average over fibre angles gives the cross-sections for the insulation material. Results for extinction and absorption compare well with direct measurements on polyester insulation materials. The scattering is found to be highly anisotropic. A properly weighted average over scattering angles, combined with the calculated absorption cross-section, gives the parameters needed for a diffusion model of radiative heat transport.

The equations describing combined radiative and conductive heat flow are solved by an approximate method, and the results are compared with measurements of thermal resistance on several samples of commercial polyester-fibre insulation. The excellent agreement, with no adjustable parameters in the theory, indicates that the diffusion model adequately describes radiative heat transport in such materials. The method is used to predict the effect of possible alterations to the fibres.

abstract: Doctor of Philosophy (PhD)


title: Static and Dynamic Critical Phenomena in Ultrathin Films of Iron on W(110)

contributor:
Venus, D.
Physics

subject: Physics Physics

abstract: The critical properties of Fe/W(110) ultrathin films with thickness between 1.5 and 2.0ML have been studied using magnetic ac-susceptibility Xm. Using a careful statistical fitting routine that allows simultaneous extraction of the critical exponent Υ and the transition temperature Tc , the Fe/W(110) films were found to belong to the 2d Ising universality class. Measuring the 2d Ising Υ value of 7/4 from the data appears to be dependent on how close to Tc the data allows fitting. This in turn is dependent upon film thickness, likely through changes in film uniformity. For measurements of the susceptibility that show power-law scaling below a reduced temperature value of 4.75x10⁻³, the average value of Υ= 1.75±.02. Further analysis of the complex susceptibility allows the extraction of the critical slowing down exponent z. It has been found that bilayer films that exhibit a static critical exponent Υ near 1. 75 show a value of z = 2.09±.06 (95% confidence). This finding represents the first experimental measurement of the critical slowing down exponent which supports the current theoretically predicted value for a 2d Ising system. Further analysis also allows insight into various saturation processes that affect the magnetic ac-susceptibility near Tc and the effect that oxygen doping of the surface has on the saturation.

abstract: Doctor of Philosophy (PhD)


title: Genetic and Biochemical Studies with Chinese Hamster Ovary Cell Mutants Resistant to the Purine Nucleoside Analogs: Toyocamyin, Formycin A and Formycin B

contributor:
Gupta, R. S.
Biochemistry

subject: Biochemistry Biochemistry

abstract:
The aim of this study was to investigate the mechanism of cellular resistance and toxicity to the purine nucleoside analogs toyocamycin, formycin A and formycin B by using genetic, biochemical and immunological approaches.

To investigate the similarity or differences in the mechanism of action of various pyrrolopyrimidine nucleosides, second-step toyocamycin resistant mutants (Toyʳᴵᴵ mutants) of Chinese hamster ovary cells were isolated from a cell line which exhibited similar degree of resistance to toyocamycin and tubercidin. These second-step mutants exhibited a further 8- to 9-fold increase in resistance to toypcamycin but no concurrent increase in their resistance towards tubercidin. The Toyʳᴵᴵ mutants were found to be very similar to the first-step mutants in their levels of adenosine kinase activity (< 1%), as well as cellular uptake and phosphorylation of adenosine and its analogs. The increased resistance of the Toyʳᴵᴵ mutants to toyocamycin but not to tubercidin provides strong evidence that the mechanism of cellular toxicity of these two analogs is different and suggests that these mutants may be affected in a cellular component which is specifically involved in the toxicity of toyocamycin. The Toyʳᴵᴵ mutants also exhibit increased resistance to sangivamycin and the tricyclic pentaazaacenaphthylene ribonucleoside, indicating that the mechanism of cellular toxicity of these two analogs may be similar to that of toyocamycin.

The genetic and biochemical approach was also used to investigate the mechanism of resistance and metabolism to another group of nucleoside analogs in which the base is linked to ribose moiety by a C-C linkage. Studies presented showed that stable mutants which are approximately 3- and 8-fold resistant to the C-nucleoside, formycin A (Fomᴿ mutants) could be obtained in a single step in CHO cells. In cell extracts, the Fomᴿ mutants contained no measurable activity of the enzyme adenosine kinase. In cell hybrids formed between formycin A resistant and sensitive cells (Fomˢ) as well as formycin A resistant and toyocamycin resistant cells (Toyʳ), the drug resistant phenotype of Fomᴿ mutants behaved codominantly as indicated by the degree of resistance of the hybrid cells to formycin B. However, extracts from these hybrid cells contained either≈50% (Fomᴿ x Fomˢ) or <1% (Fomᴿ x Toyʳ) AK activity indicating that the lesion in these mutants neither suppresses the wild-type AK activity nor complements the AK deficiency of the Toyʳ mutants. Cross-resistance studies with various adenosine analogs show that these mutants are distinct from the Toyʳ mutants, which also contained no measurable AK activity in cell extracts. The Fomᴿ mutants exhibited a high degree of cross-resistance to different C-nucleosides but did not show appreciable cross-resistance to different N-nucleosides examined. In contrast, mutants selected in presence of toyocamycin exhibited a high degree of cross-resistance to both N- as well as C-nucleosides which are phosphorylated via adenosine kinase. Studies on the cellular uptake and phosphorylation of radiolabelled N- and C-nucleosides by various mutant lines showed that, unlike the Toyʳ mutants which show greatly reduced phosphorylation of all adenosine analogs (both N- and C-nucleosides), the Fomᴿ mutants showed reduced cellular phosphorylation of only C-nucleosides but not of N-nucleosides. The normal level of phosphorylation of N-nucleosides in the Fomᴿ mutants suggested that the Fomᴿ mutants contain normal levels of AK activity in vivo. The above observations together with the specific cross-resistance of these mutants to C-nucleosides as well as the reduced phosphorylation of such nucleosides, provides strong suggestive evidence that the Fomᴿ mutants contain a novel genetic lesion affecting adenosine kinase which specifically affects the phosphorylation of only C-purine nucleosides.

Since formycin A under the normal cell culture condition is rapidly deaminated to the inosine analog, formycin B, cellular toxicity and resistance of formycin B was also investigated. Mutants of CHO cells selected for resistance to formycin B (Fomʳ mutants) were found to be 5- to 8-fold resistant to this drug. Cross-resistance studies with these mutants revealed that they exhibit increased resistance to all adenosine analogs (N- and C-nucleosides); as well as reduced cellular uptake and phosphorylation. However, unlike the Fomᴿ and Toyʳ mutants, which contained no AK activity in their cell extracts, the Fomʳ mutants were found to contain between 60 - 110% of WT activity in their cell extracts. The AK activity present in both Fomʳ mutant cell extracts differed from the WT AK activity in terms of its specific activity as well as in its ability to phosphorylate adenosine analogs. The AK activity from the Fomʳ mutants was found to have less affinity for phosphorylation of the formycin A derivative, Bbb-85. Like Toyʳ mutants, Fomʳ mutants were found to show recessive-behaviour in cell hybrids.

Biochemical studies on the metabolism of formycin B indicated that upon incubation with CHO cells, [³H]formycin B is metabolized into formycin B-5'-monophosphate, formycin A-5'-monophosphate and higher phosphorylated derivatives of formycin A which are incorporated into RNA. All three different classes of mutants affected In AK exhibit appreciable cross-resistance as well as reduced cellular uptake and phosphorylation of formycin B. These observations strongly indicate that in CHO cells, formycin B is phosphorylated via AK and like other nucleoside analogs, its phosphorylation is essential for the cellular toxicity. Formycin B-5'-monophosphate and formycin A-5'-monophosphate have been found to inhibit the purine nucleotide biosynthetic enzyme adenylosuccinate synthetase.

To gain further insight into the nature of genetic and biochemical alterations in different types of mutants affected in adenosine kinase, this enzyme from CHO cells was purified to homogeneity. Antibodies which specifically cross-react with adenosine kinase have been raised. Immunoblot analyses using these antibodies showed that all three classes of mutants i.e., Toyʳ, Fomᴿ and Fomʳ contained nearly similar amounts of cross-reacting material that had a similar electrophoretic mobility to the enzyme in the WT cells. These results indicate that the lesion in these mutants does not involve a deletion or regulatory type of genetic alteration in the AK gene nor a nonsense type of mutation which may cause premature chain termination. Instead, these mutants may contain a missense type of alteration in the structural gene of AK. Using these antibodies, regions (or spots) on two-dimensional gels that correspond to the AK protein have been identified. Comparison of the 2-D gel electrophoretic patterns of total cellular proteins from different-mutant lines indicates that some of the mutants show a specific alteration in this region. This supports the inference that these mutants may contain a missense type of mutation in the structural gene of AK.

The results presented in this thesis have been presented or submitted in the following publications.

1. Mehta, K.D. and Gupta, R.S. (1983) Formycin B-Resistant Mutants of Chinese Hamster Ovary Cells: Novel Genetic and Biochemical Phenotype Affecting Adenosine Kinase. Mol. Cell. Biol. 3, 1468.

2. Gupta, R.S. and Mehta, K.D. (1984) Genetic and Biochemical Studies on Mutants of CHO Cells Resistant to 7-Deazapurine Nucleosides: Differences in the Mechanisms of Action of Toyocamycin and Tubercidin. Biochem. Biophys. Res. Commun. 120, 88.

3. Mehta, K.D. and Gupta, R.S. Novel Mutants of Adenosine Kinase Specifically Affected in the Phosphorylation of C-Nucleosides. Manuscript submitted to FEBS Lett.

4. Mehta, K.D. and Gupta, R.S. Metabolism and the Mechanism of Action of Formycin B in Chinese Hamster Ovary Cells: Involvement of Adenosine Kinase in Drug Phosphorylation. Manuscript submitted to J. BioI. Chem.

abstract: Doctor of Philosophy (PhD)


title: Characterization of the Chromosomal Aminoglycoside 6' -N-Acetyltransferase from Enterococcus faecium

contributor:
Wright, G.D.
Biochemistry

subject: Biochemistry Biochemistry

abstract: The clinical utility of aminoglycoside antibiotics is undermined by the action of bacterial modifying enzymes that inactivate these antimicrobial agents and confer drug resistance. Basic research on the aminoglycoside modifying enzymes has contributed to a greater understanding of the molecular mechanism of aminoglycoside detoxification by these proteins, information that is relevant to inhibitor studies and other approaches aimed at reversing bacterial aminoglycoside resistance in vivo. Described here is the characterization of AAC{6')-li, a chromosomally encoded aminoglycoside 6' -Nacetyltransferase from the Gram positive pathogen Enterococcus faecium and a member of the GCNS-related superfamily of acyltransferase enzymes. Research on AAC{6')-li has focused on the kinetic and catalytic mechanism of aminoglycoside modification by this enzyme, in addition to inhibitor studies and investigations into a possible alternate role for this acetyltransferase in vivo. Using steady state-kinetic analysis of product and dead-end inhibition of protein activity, we have determined that AAC{6')-li follows a ternary complex, ordered bi-bi kinetic mechanism, with additional evidence supporting subunit cooperativity in the AAC{6')-Ii dimer. This work was complemented by studies that characterized substrate-induced conformational changes in AAC{6')-Ii, as well as analysis of solvent viscosity and isotope effects that identified the catalytic steps governing the steady-state rate of aminoglycoside inactivation. Together with the structural details of AAC{6')-li in complex with AcCoA, site-directed mutagenesis and related studies have also identified amino acid residues important to the chemistry of drug acetylation as well as those involved in the binding of aminoglycoside substrates, providing us with a better understanding of the molecular mechanism of AAC(6')-Ii catalysis. Our results to date have been applied to numerous inhibitor studies, which have resulted in the identification of cationic peptides and semisynthetic aminoglycosides that demonstrate potent inhibition of AAC(6')-Ii activity in vitro. Finally, the acetylation of E. faecium proteins by AAC(6')-Ii has been shown by both in vitro and in vivo analysis, complementing the structural and functional homology observed for this enzyme and protein acetyltransferases, in addition to supporting our hypothesis that AAC(6')-Ii may have an alternate function in the host bacteria. As a whole, these studies have extensively characterized the activity of AAC(6')-Ii, which is relevant to ongoing and future inhibitor studies and to an understanding of the similarities and differences among enzymes in the GCNS-related N-acetyltransferase superfamily.

abstract: Doctor of Philosophy (PhD)


title: MOLECULAR IMAGING USING FEMTOSECOND LASER PULSES

contributor:
Corkum, Paul B.
Physics

subject: Physics Physics

abstract: Recent technological advances have brought the possibility of directly imaging polyatomic molecular dynamics within reach. Consequently, several diffractive and non-diffractive time-resolved imaging techniques are currently under development worldwide. The work described here was motivated by the desire to pioneer the femtosecond laser-initiated Coulomb explosion approach to molecular imaging. The research project's original objective has been met using a unique instrument that can measure and correlate multiple three-dimensional ion velocities. Using this state-of-the-art machine, the first Coulomb explosion images of triatomic molecules have been produced. Furthermore, the apparatus has been employed to demonstrate that existing ultrafast laser technology is sufficient to confine virtually any molecule inertially during its multiple ionization. In conjunction with the instrument's novel capabilities, the Coulomb explosion process has been exploited in numerous other applications. For instance, a time-resolved method for directly imaging rotational wave packets in diatomic molecules has been demonstrated. Further, a high-sensitivity technique has been developed for detecting non-sequential "shake-off' double ionization in molecular deuterium. In other experiments, the optical timing of ion flight has been demonstrated, which should enable the fabrication of the world's smallest time-of-flight mass spectrometer. Finally, the instrument's excellent momentum resolution has given rise to an entirely new technique for observing molecular dynamics: electron self-diffraction imaging.

abstract: Doctor of Philosophy (PhD)


title: THE EFFECTS OF EXERCISE TRAINING ON CARDIOVASCULAR REGULATION IN INDIVIUALS WITH SPINAL CORD INJURY

contributor:
Hicks, Audrey
Kinesiology

subject: Kinesiology Kinesiology

abstract: Introduction. Individuals with spinal cord injury (SCI) are prone to severe cardiovascular dysfunction and an increased risk of mortality from various cardiovascular diseases. The underlying mechanisms responsible for the increased cardiovascular risk are not precisely understood, however, the reduced activity levels that accompany SCI certainly contribute. Unfortunately, muscular paralysis (partial or complete) limits the exercise options for individuals with SCI and the role of exercise rehabilitation as a means of reversing cardiovascular risk is not fully understood in this population. Recently developed methods may be particularly useful in evaluating the effects of exervise on the cardiovascular health and function in individuals with SCI. Specifically, power spectral analysis of heart rate variability (HRV) and blood pressure variability (BPV) have become commonly used, non-invasive methods used to quantify the autonomic control of the cardiovascular system. Clinically, measures of HRV and BPV have particular value as relatively decreased cardiac vagal predominance has been associated with an increased risk of cardiovascular mortality, and increased BPV is associated with end organ damage. In addition, Doppler ultrasound imaging techniques allow for the determination of arterial dimension and function. As such, these imaging techniques may be used to determine arterial blood flow and vascular compliance; the latter referring to the ability of the vessel to expand and recoil during changes in intravascular pressure. Clinically, these measures are also of value as reductions in blood flow contribute to thrombus formation, in addition to delayed wound healing and an increased risk of pressure sore formation, while reductions in arterial compliance are a contributing factor to vascular damage, and the associated risks of thrombosis, myocardial infarction and stroke. The primary purpose of this thesis was to examine the effects of exercise training on resting measures of HRV, BPV and arterial dimension and function in individuals with SCI. A secondary purpose, was to determine the effects of exervise training on the ability to tolerate orthostatic stress in individuals with SCI. Although the first training study in this thesis used arm ergometry and resistance training as the exercise stimulus, the principle mode of exercise training that was used was body-weight supported treadmill training (BWSTT) as it may be particularly well suited as a cardiovascular stimulus in the SCI population. Specifically, BWSTT is an upright exercise that involves the legs, and may be performed without the risks that are commonly associated with functional electrically stimulated (FES) exercise such as burns to the skin, stimulation-induced pain and autonomic dysreflexia. It was hypothesized that BWSTT would result in i)positive changes in the autonomic regulation of the cardiovascular system, as indicated by measures of HRV and BPC, AND II) positive changes in arterial dimension and function, as indicated by Doppler ultrasound measures. Regarding the effects of exercise training on orthostatic tolerance, previous work has provided some evidence that exercise training confers an enhanced ability for individuals with SCI to respond to cardiovascular stress. On the other hand, it was also reasonable to hypothesize that potential training-induced reductions in sympathetic outflow and arterial resistance would decrease the ability to tolerate postural stress in individuals with SCI. Methods. Short-term, continuous ECG and blood pressure (Finapres) recordings were taken before and after exercise training in individuals with SCI and used to determine measures of HRV and BPV, respectively. In addition, Doppler ultrasound imaging was performed on the femoral and carotid arteries, before and after exercise training, in order to determine vascular dimension and function. All testing was conducted in the resting supine position and during an orthostatic stress (60∘head-up tilt). Results. 1. Measures of heart rate variability (HRV) and blood pressure variability (BPV) were found to be reproducible in individuals with SCI, regardless of the level of injury. As such, clinicians and researchers may be encouraged to use these measures to determine the effectiveness of various interventions on the cardiovacular health in the SCI population. 2. Individuals with incomplete tetraplegia were found to retain the ability to make positive changes in cardiac sympathovagal balance following 3 months of combined arm ergometry and resistance exercise training. No exercise-induced changes were noted in orthostatic tolerance. 3. The results of the third study demonstrated that individuals with incomplete tetraplegia can make positive adaptation to the autonomic regulation of the cardiovascular system following 6 months of BWSTT as indicated by measures of HRV and BPV. In addition, these adaptations occurred without an accompanying tendency to become less tolerant of orthostatic stress. 4. The results of the fourth study showed that individuals with motor-complete SCI may experience favourable vascular changes following 4 months of BWSTT. Although there were no significant exercise-induced changes in measures of HRV and BPV, the results suggested that favourable changes in both these measures may occur in individuals who rexperience a substantial heart rate (HR) response to this type of training. Greater HR responses were elicited in those who were more orthostatically intolerant and had greater muscle spasticity. Finally, BWSTT was found to women worsen orthostatic intolerance in individuals with tetraplegia, but not in those with paraplegia. Conclusions. Individuals with SCI retain the ability to make positive changes in cardiovascular regulation with exercise training, as indicated by measures of HRV and BPC, as well as by Doppler ultrasound measures of arterial function. Individuals with less severe SCI (ASIA C and D injuries) may be particularly well suited for BWSTT as a means to promote cardiovascular improvement. Specifically, individuals with spared motor function (ASIA C injuries) made positive adaptations in meaures of HRV and BPC after 6 months of BWSTT, and further, due to the spared sensory ability, these individuals may not be able to tolerant FES exercise. Individuals with motor-complete SCI may experience positive vascular changes with BWSTT, regardless of the HR elicited during this form of exercise. In addition, those with high muscle spasticity and a susceptibility to orthostatic intolerance may experience positive adaptations in measures of HRV and BPV.

abstract: Doctor of Philosophy (PhD)


title: Sorption Equilibria and Kinetics of Sequential Sorption in Zeolite Molecular Sieves

contributor:
Anderson, R.B.
Chemical Engineering

subject:
Chemical Engineering
Chemical Engineering

abstract:
The counter-diffusion of a series of low moIecuIar weight, permanent gas sorbate pairs on synthetic zeolites of various pore-geometries and dimension, was investigated in a semi-automatic flow system. Results of the binary diffusion studies were compared to the single component kinetics of the same species to determine the effect of the adsorbate/desorbate interactions as well as the relationship between the zeolitic pore dimension and molecular size and the respective contributions to the binary diffusion rates.

Equilibrium studies of the individual sorbate molecules were carried out in a conventional BET volumetric apparatus. The experimental isotherms were correlated to a two-dimensional analog of a three-dimensional virial equation with good results.

Existing diffusion models applicable to the binary sorption system were investigated. Also, a novel kinetic model for diffusion in zeolites based on the principle of random walk has been developed. Qualitatively, the model produces many of the pertinent features observed in the experimental studies.

abstract: Doctor of Philosophy (PhD)


title: High Temperature Gaseous Desulfurization Using Cerium Oxides and Bastnaesite Concentrates

contributor:
Kay, D.A.R.
Chemical Engineering

abstract:
The high temperature gaseous desulphurization characteristics of calcined bastnaesite concentrates and cerium oxides have been investigated. The former is a solid solution of rare earth oxyfluorides (RE = La, Nd, Pr) and CeO₂, and has a fluorite type structure. The presence of dissolved CeO₂ in these concentrates is believed to be responsible for the reduction, desulfurization and regeneration characteristics of this mineral.

The chemistry of the desulfurization and regeneration process has been elucidated using a fixed bed of cerium oxide at high temperatures (800-1000°C). Coal gases, similar in composition to those generated by a Koppers-Totzek gasification unit, were desulfurized from 1.0% H₂S by volume to less than 4 ngS/mL (3 ppm) in a laboratory scale reactor. This represents a desulfurization efficiency of 99.98%. Desulfurization takes place through a non-catalytic gas-solid reaction where the reactant is in the form of a non-stoichiometric oxide, CeO₂_n.

2CeO₂_n(s) + (1-2x)H₂(g) = Ce₂O₂S(s) + 2(1-x)H₂O(g)

Adsorption of sulfur is facilitated by the presence of oxygen vacancies in the reduced sorbents. An interactive computing system was used in conjunction with the Ce-O-S phase stability diagram to predict the compositions of reactants and products in terms of the sulfur and oxygen potentials of the gas phase.

Regeneration of spent sorbents occurs readily in air, with the evolution of sulfur dioxide:

Ce₂O₂S(s) + O₂(g) = 2CeO₂(s) + SO₂(g)

Desulfurization efficiencies of cerium oxide compared favourably with those of similar high temperature technologies using iron oxide, limestone or dolomite.

abstract: Doctor of Philosophy (PhD)


title: CARRIER MEDIATED LIPID TRANSPORT

contributor:
Trigatti, B.L.
Biochemistry

subject: Biochemistry Biochemistry

abstract: Lipids are essential molecules for cellular function; they are required for energy production, membrane structure, and can serve as signaling molecules. Normal metabolism requires cellular uptake and efflux as well as intercellular transport of lipids. Disruption of these events can lead to pathological processes like obesity and atherosclerosis. Transport of lipids between tissues involves moving hydrophobic species through a polar environment. This is achieved by carrier mediated lipid transport. These carriers can have significant impact on cellular uptake and efflux of lipids. This thesis investigated carrier mediated lipid transport in two situations, 1) long chain fatty acids (LCF As) and the carrier protein albumin, and 2) cholesterol (and other lipids) carried by high density lipoprotein particles. Significant issues regarding cellular LCF A uptake from albumin remain unresolved. 1) How do LCF As traverse the plasma membrane, and 2) is an albumin receptor involved in LCF A uptake? With respect to the first question, we hypothesized that the mechanism of LCFA uptake may be sensitive to cellular cholesterol. Our studies concluded that cholestrol-depleting agents inhibit LCFA uptake but not that of a non-carrier mediated subtrate. In regard to the second question, we investigated if albumin binding proteins exist on the cell surface of adipocytes. We found that albumin binding activity increased as cells undergo adipogenesis, and candidate proteins for this activity were found. We also investigated the role of the high density lipoprotein (HDL) receptor, scavenger receptor class B type I (SR-BI) in cholesterol metabolism and atherosclerosis. SR-BI has been found to be atheroprotective in mice, and this may involve cholesterol efflux from macrophage foam cells to HDL. We investigated the affect of bone marrow specific ablation ofSR-BI on atherosclerosis in mice. We concluded that SR-BI expression in bone marrow- erived cells can protect against atherosclerosis in the absence of any changes in overall lipoprotein metabolism. concluded that cholesterol-depleting agents inhibit LCF A uptake but not that of a noncarrier mediated substrate. In regard to the second question, we investigated if albumin binding proteins exist on the cell surface of adipocytes. We found that albumin binding

abstract: Doctor of Philosophy (PhD)


title: Factors Controlling Oxygen Depletion in the Hypolimnion

contributor:
Snodgrass, W. J.
Chemical Engineering

abstract:
The purpose of this research was to determine the factors controlling oxygen depletion in the water column (more specifically, the hypolimnion).

Five factors were hypothesized to be important:

1. Soluble organic carbon concentration

2. Temperature

3. Nutrient concentration

4. Initial oxygen concentration

5. Algal respiration

These factors were related by a two-level Factorial Experimental Design. Two separate but related Designs were used to "block" and "average" the effects, allowing for differentiation between main effects (for example, temperature) and two-factor interactions (for example, the combined effect of soluble organic carbon concentration and temperature).

Four bodies of water (Hamilton Harbour, Guelph reservoir, Red Chalk Lake, and Chub Lake) were tested. The results show that in all cases, except Chub Lake, temperature is the most important factor controlling oxygen depletion. Soluble organic carbon concentration is the most important variable in Chub Lake. The second most important variables are: soluble organic carbon concentration in Hamilton Harbour and Red Chalk Lake, temperature in Chub Lake and the initial oxygen concentration in the Guelph Reservoir. The remaining factors have varying degrees of importance depending on the water body. This suggests that biodegradation is not limited by nutrients and that algal respiration is a small component of oxygen consumption.

In addition to these main studies, Temperature and Oxygen Kinetics were also investigated. The Temperature Kinetic experiments showed that higher temperatures produce higher oxygen uptake rates. The Oxygen Kinetic experiments showed no trends except when Hamilton Harbour water was tested. In Hamilton Harbour, higher initial oxygen concentrations produced higher oxygen uptake rates.

It is proposed that the Experimental Design represents a bioassay on oxygen consumption. It represents quantification of biodegradation under standard conditions. The relative magnitudes of oxygen consumption under these standard conditions correlate with empirical ideas of degradability of organics in the different water bodies. More work is required to refine the scaling of factors selected, seasonal variability, etc.

abstract: Master of Engineering (ME)


title: Electrode geometry effects on the collection efficiency of submicron and ultrafine dust particles in wire-plate electrostatic precipitators

contributor:
Chang, J.S.
Findlay, R.D.
Electrical and Computer Engineering

abstract: Recent interest in emission control of fine particulate matter has resulted from scientific studies on the effect of fine particulate matter on human health. Hence, many western countries introduced a new emission regulation known as PM2.5, that regulates particles less than 2.5 microns in diameter. The existing particle separation devices such as electrostatic precipitators (ESPs) are of particular interest since they can economically capture particles effectively with a low pressure drop. The present ESPs provide high collection efficiencies of around 99.99% for micron and larger particles. However, the collection efficiency of submicron particles in the range from 0.1 to 1 ~m and ultrafine particles, that is with particle diameters less than 0.1 Jlm, can be less than 50%. In this work, numerical and experimental studies were conducted to examine the effect of electrode geometries on the improvement of collection efficiency of submicron and ultrafine dust particles in electrostatic precipitators. The collection efficiency prediction was based on a modified Deutsche's equation after calculation of the three-dimensional electric potential and ion distribution. The particle charging models for diffusion and field charging methods were considered, based on the Knudsen number (Kn=2A/dp), where Ai is the mean free path of negative ions and dp is the dust particle diameter. The constitutive relationship developed from the optical emission experiments was implemented to simulate ion distribution of corona discharge for various discharge electrodes. Experimental validations for total and partial collection efficiencies for particle size from 10-2 to 20 mm were conducted for bench and full scale ESPs. Results show that the collection efficiency of submicron and ultrafine particles can be predicted with good accuracy for various geometries of discharge and dust collection electrodes. The spike-type discharge electrode with the I-type collecting electrode improves collection efficiency of fine particles when compared to the wire or rod discharge electrode with I-type collecting electrode. In the case of U and C-type collecting electrodes, there is an optimum fin length for which the highest collection efficiency can be reached. Comparison of experimental and predicted results shows that the total collection efficiency predicted by the present model agrees well with experimental results for the bench-scale ESPs. For the large-scale wire-plate type ESP, the present simulation results conducted for various gas temperatures and dust resistivities agree quantitatively and qualitatively with the experimental results. The model proved to be useful for prototype design of collecting and discharge electrodes, modification and existing ESP's and scale-up of new ESP's in order to meet new emission regulations.

abstract: Doctor of Philosophy (PhD)


title: Genotoxic and Carcinogenic Activity of Oil Refinery Effluents

contributor:
Sonstegard, R. A.
Biology

subject: Biology Biology

abstract:
Concentrated extracts were prepared from particulate, dissolved, and volatile components of effluents from three low-temperature cracking refineries. Extracts were tested for genotoxic activity using the Ames bacterial mutagenicity assay, and an in vitro assay for sister chromatid exchange. The dissolved and volatile components of effluents showed little genotoxic activity, but particulate extracts from two of three refineries sampled were significantly mutagenic. One particulate sample gave a positive response in the sister chromatid exchange (SCE) assay. All samples required exogenous activation with rat-liver microsomes (S-9) for expression of genotoxic activity. Subfractionation of particulate extracts indicated that mutagenic activity was concentrated in neutral, polar fractions.

The mutagenic/carcinogenic hazard associated with the chlorination of water contaminated with oil refinery effluents was also investigated. Non-volatile agents with mutagenic (Ames test) and clastogenic (SCE) activity were formed by chlorination of dilute refinery effluents. These compounds were direct-acting, in that the addition of S-9 was not required for genotoxic activity. Contact time with chlorine, chlorine concentration, effluent concentration, and the pH of the reaction mixture were found to vary the mutagenicity of the extracts.

The effluent extracts were tested for carcinogenicity using an in vivo embryo assay developed for these studies. Microlitre volumes of extracts were injected into eyed rainbow trout embryos, and the fish raised for 12 months before necropsy. Refinery extracts were not directly carcinogenic. Coinjection of aflatoxin B₁ with extracts from both the particulate and dissolved components of effluents significantly increased the incidence of hepatic carcinomas. This co-carcinogenic effect was most pronounced when the extracts and aflatoxin B₁ were preincubated with rat S-9 before embryo injection. Effluent extracts coinjected with a direct-acting carcinogen, N-methyl -N'-nitro-N-nitrosoguanidine (MNNG), did not increase the incidence of hepatic carcinomas.

abstract: Doctor of Philosophy (PhD)


title: Minority Churches Among Japanese Canadians: A Sociological Study

contributor:
Greenspan, Louis
Religious Studies

subject: Religion Religion

abstract: This dissertation elaborates and applies the subtypology of minority churches initially designed by Millett (1969) for the study of religion in Canada. The utility of this framework for comparative sociological research was considered through an empirical analysis of the two largest minority church organizations within the Japanese Canadian community: the "foreign~oriented" Buddhist Churches of Canada (BCC) with 18 congregations, and the "nativeoriented" Japanese United Church Conference (JUCC) with 11 congregations. From a review of the literature on religion and ethnicity, two central questions were identified to provide the orientation for this study: (1) Are Japanese minority churches effective agents of cultural preservation in Canadian society? or (2) Does the assimilation process force Japanese churches to de-ethnicize and accommodate to the acculturated generations for organizational survival? The significance of Millett's sub-typology for organizational analysis was explored in relation to these key issues. In comparing the effectiveness of these minority churches as social forces for ethnic persistence, it was hypothesized that the foreign-oriented BCC would have shown a greater concern to maintain ethnicity than the native-oriented JUCC. On the issue of organizational change, it was hypothesized that the native-oriented JUCC would have been better able to make adaptations for the acculturated generations than the foreign-oriented BCC. Although the divergent patterns of ethnic persistence and organizational adaptation suggested by the sub-typology were only partially supported by the data, the comparative analysis did demonstrate its heuristic value. The typology draws attention to important factors which should be recognized in the study of ethnic religious organizations. The character of the "administrative reference group" and the different "membership orientations" are clearly significant variables influencing the course of minority church evolution. This dissertation concludes that minority churches are most accurately viewed as transitional organizations. The organizational dilemmas confronting both the BCC and JUCC as a result of advanced assimilation indicate that in most cases these churches face either organizational dissolution or transformation into multi-ethnic congregations within another generation. The assimilation of Japanese in Canada and the precarious future of most minority churches casts serious doubt upon the long-term survival of ethnic subcultures in Canadian society.

abstract: Doctor of Philosophy (PhD)