title: Synthesis and Property Optimization of Ordered, Aryl Dense Polysiloxanes Using Boron Catalysis

contributor:
Brook, Michael A.
Chemistry and Chemical Biology

subject:
Siloxanes
Piers-Rubinsztajn
Boron Catalysis
Aryl Silicones
Functional Elastomers
High-Throughput Synthesis
Hydrolysis

abstract:
Silicones are widely used polymeric materials due to their unique properties. The material properties of silicones may be altered by incorporating various organic groups. Traditional methods for linear silicone synthesis involve ring-opening polymerization, which leaves the growing chain susceptible to acid or base mediated chain redistribution and the formation of cyclic monomer byproducts. The Piers-Rubinsztajn (PR) reaction is an alternative siloxane synthetic route that avoids the use of tin- or platinum- based, or of Brønsted acid/base catalysts. Siloxane bond formation is catalyzed by tris(pentafluorophenyl)borane (B(C6F5)3) (R’3Si-H + RO-SiR”3 → R’3Si-O-SiR”3 + RH); alkoxysilanes can be replaced with silanols or alkoxybenzenes.
The catalytic activity of B(C6F5)3 was shown to be hindered by trace water in solution; water acts as a Lewis base coordinating to B(C6F5)3. Since the hydrate-free form of B(C6F5)3 is required to initiate a PR reaction, water can act as an inhibitor. In a somewhat contradictory fashion, water was also shown to react with hydrosilanes via a B(C6F5)3 catalyzed hydrolysis reaction to give silanols, that themselves are reagents for the process.
The reactivity of alkoxysilanes (or aryl ethers) in the PR reaction was found to be much quicker than water. This was exploited in the synthesis of Ax(AB)yAx triblock copolymers. The aryl rich AB core was first synthesized using the PR reaction. Excess silicone condensed via hydrolysis forming the A blocks. This method of exploiting relative reactivity to tune structure was applied to elastomers made using a single linker (eugenol) with multiple functional groups – elastomer morphology was controlled by changing order of addition.
The development of aryl dense silicones is of interest for use in electronic devices. Phenylmethyl homopolymers and highly ordered phenyl pendant copolymers (Ph/Si ratio of 0.5-1.5) were synthesized from monomers to give polymers with high refractive indices (1.51-1.59) and Mw up to 170 kDa. Statistically relevant libraries of aryl functional silicones were developed using combinatorial chemistry in order to analyze their structure-property relationship. Incorporating aromatic groups into silicones worked to elevate thermal stability, refractive index and improve the mechanical strength of silicone rubbers.

abstract: Thesis

abstract: Doctor of Science  (PhD)

abstract: Silicone fluids and elastomers possess numerous desirable characteristics which leads to their use in a wide range of applications in the automotive, electronics and biomedical fields, among others. Developing techniques to create well defined, ordered, modified silicones with improved optical properties, mechanical strength and thermal stability was the main focus of this thesis. These objectives were accomplished by incorporating aromatic groups into silicones using boron catalysis. Following the initial (intended) Piers-Rubinsztajn reaction, atmospheric moisture was utilized to promote further polymerization. Statistically relevant libraries of silicone elastomers were prepared using both standard and combinatorial chemistry techniques. This library of elastomers permitted the analysis of trends associated with small changes in elastomer formulation, which could not be accomplished using traditional one-by-one reaction methods in a timely fashion. The modified silicone materials exhibited high refractive indices (up to 1.59), elevated stiffness and improved thermal stability (maintain structure up to 500 °C) when compared to previously synthesized polymers.


title: Tunnel Valley Genesis and Subglacial Dynamics in South-Central Ontario

contributor:
Eyles, Carolyn
Geography and Earth Sciences

subject:
tunnel valleys
subglacial dynamics
drumlin
Laurentide Ice Sheet
subglacial till
Hydrogeology
southern Ontario
Oak Ridges Moraine
Newmarket Till
Peterborough drumlin field

abstract:
Glacial sediments are found across formerly glaciated regions across the world and host a variety of important resources, ranging from groundwater to hydrocarbons, aggregate material, and mineral deposits. In southern Ontario, Canada, thick successions (up to 200 m) of Quaternary glacial sediments are truncated by large valleys (>30km long, 2 to >8.5 km wide, and up to 200m deep) that formed subglacially and have characteristic morphology and infill stratigraphy. These valleys are interpreted as (a new class of) tunnel valleys and strongly affect groundwater resources and flow systems at local and regional scales.
The overall context of the valleys is evaluated through an introduction to the study area, objectives, and background information on subglacial systems and geologic history of south-central Ontario (Chapter 1). Interpretation of valley genesis in Simcoe County is provided through an integrated, multi-faceted approach, involving: description of the morphology and sediment infill succession within the valleys from surficial mapping, sedimentological logging of continuously-cored boreholes, and geophysical surveys (Chapter 2); delineation and characterization of seismic architecture from high-resolution lake-based sub-bottom profiles in one of the valleys (Chapter 3); detailed site-scale field description of the internal characteristics of the regional Late Wisconsin till sheet in various subglacial settings (Niagara Escarpment, uplands, lowlands; Chapter 4); comparison of the characteristics of the subglacial bed within the study area to adjacent regions in southern Ontario (Chapter 5); and a synthesis of the major findings from all the different components of this investigation and suggestions for future work to shed further light on several questions that arise from this study (Chapter 6). Together, key data from these studies of tunnel valleys and related deposits – a near-continuous till sheet on the surface of uplands and along the flanks and floors of the tunnel valleys, multi-stage drumlinization of the till sheet following development of the tunnel valleys, variations in internal facies and physical properties within the till sheet in different subglacial settings, localized distribution of coarse-grained tunnel valley in-fill sediments, and gradational upward transitions from tunnel valley in-fills to fossiliferous proglacial lacustrine sediments –  indicate multiple phases of subglacial meltwater, and direct subglacial, erosion and deformation contributed to the development of the valleys over a protracted time period during the Late Wisconsin. Landform and sediment associations within the valleys in Simcoe County and surrounding parts of the bed of the former Laurentide ice sheet in south-central Ontario, are inconsistent with previous conceptualizations involving the presence of large (>1000 km2) subglacial lakes and the storage and discharge of regional-scale subglacial meltwater sheetfloods followed by ice stagnation. This study provides new data and insight to help refine reconstructions and better understand the evolution of past ice dynamics and subglacial processes, evaluate competing theories of regional landscape evolution, and provide new conceptual and (hydro)stratigraphic frameworks for future hydrogeological investigations related to groundwater exploration and use.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Encapsulation of rolling circle amplification product in hydrogel systems for applications in biosensing

contributor:
Filipe, Carlos
Hoare, Todd
Chemical Engineering

subject:
Biosensing
Hydrogel
Rolling Circle Amplification
Microarray

abstract: The development of easily fabricated, highly stable DNA-based microarray and continuous flow concentrating devices is vital for several biomedical and environmental applications. Nucleic acid biosensors can be used for genetic analysis, disease diagnosis, drug discovery, food and water quality control and more, however methods of fabrication are tedious, and the longevity of sensors is compromised by the fragility of the sensing component. In this report, the fabrication and characterization of two biosensing modalities – microarrays and microgels – composed of Rolling Circle Amplification (RCA) product in poly(oligoethylene glycol methacrylate) (POEGMA) hydrogels are investigated. RCA product microarrays were developed by the sequential printing of aldehyde and hydrazide functionalized POEGMA precursors on nitrocellulose paper, exploiting rapid gelling via hydrazone crosslinking to generate thin film hydrogel sensing arrays. POEGMA/RCA product microgels for affinity column applications were synthesized using an inverse emulsion polymerization technique. Inkjet printing evenly deposited RCA product in all wells, with POEGMA effectively stabilizing DNA on the cellulose substrate. Hybridization of complementary probe to the encapsulated RCA product was optimized, yielding a signal to noise ratio of ~4 for a large range of probe concentrations. Microgels were successfully synthesized in the size range of 10-60 μm diameter, and a linear model that can accurately predict size based on initiator and emulsifier concentration was developed. The encapsulation efficiency of RCA product in different sized microgels was explored, with larger microgels entrapping more product and the highest encapsulation efficiency calculated at 56%. These results demonstrate that POEGMA hydrogels can be utilized to encapsulate and stabilize RCA product in two distinct structures, providing a basis for the development of easily fabricated biosensors for more specific applications.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: The Construction of Risk in Childbirth in Rural Zimbabwe: The Case of Traditional Midwifery

contributor:
Willms, Dennis
Anthropology

subject:
childbirth
rural Zimbabwe
Zimbabwe
traditional midwifery
midwifery
construction of risk in childbirth
risk in childbirth
construction of risk
medical anthropology
anthropology

abstract: This thesis is based on a study that was conducted in the Manicaland Province of Zimbabwe during the period 1996-1997. The main objective of the study was to identify factors in traditional midwifery that facilitate the vulnerability of both the birthing woman and the traditional birth attendant (TBA) to risks in childbirth. Traditional birth attendants in Zimbabwe, though for a long time a shunned and ridiculed cadre, have always been the custodians of maternal health in the rural areas. TBAs have traditionally relied on intuition and hands-on-experience in their day-to-day practice. With the government's adoption of the upgrading programme for TBAs as a Primary Health Care initiative to reduce infant and maternal mortality, TBAs in Zimbabwe have since incorporated some of the modern obstetric methods into their own traditional practices. There is yet another group of TBAs, who regardless of the training programme, have continued dependence on their experiential and intuitive knowledge for delivery of health. Traditional Birth Attendants, as well as the rural women with whom they share an explanatory model of birthing, were consulted in this study in order to get an emic understanding of risk construction, which in turn would inform intervention strategies. It was hoped that the fusion of these conceptual categories (indigenous with biomedical), would contribute to a body of knowledge which would be a foundation for culturally compelling interventions to reduce risks in traditional birthing practices. As this study unfolded, it became apparent that not only was the women's preference for the TBA determined by cultural forces, but that there were a myriad of additional, contextual forces at play. Macro-processes affecting TBA practices are noted, and issues analyzed from the broader perspective of critical medical anthropology (CMA).

abstract: Thesis

abstract: Master of Arts (MA)


title: Managing Discourse: Medical Heresy, Integrative Medicine, and the Therapeutic Touch Debate

title: Managing Discourse: The Therapeutic Touch Debate

contributor:
Rodman, Bill
Anthropology

subject: medical heresy

subject: integrative medicine

subject: therapeutic touch

subject: discourse

subject: managing discourse

subject: medical heresy, integrative medicine, and the therapeutic touch debate

subject: anthropology

subject: Therapeutic Touch

subject: Therapeutic Touch debate

subject: therapeutic touch debate

abstract: In this thesis I examine the debate surrounding Therapeutic Touch, a controversial energetic healing modality being practiced by registered nurses in biomedical institutions across North America. The debate surrounding the therapy takes place within medical journals, popular media articles, and on the internet. Within the debate, definitions of illness etiology, appropriate treatment, patient management, and alternative therapy use are contested by Therapeutic Touch proponents and critics. Through discursive analysis, interviews with local participants in the debate, and participant observation within the TT community, I present an analysis of the issues being contested and of the discursive strategies used by proponents and critics within the debate. The debate is contextualized in two ways: first, as an instance of medical heresy, in which an alternative healing group arises within the orthodox medical community and struggles to maintain itself within biomedical discourse and institutions; second, I contextualize the debate as an example of the wider trend towards integrative medicine in North America. Integrative medicine sees alternative therapies being increasingly used within health care delivery systems, either by alternative practitioners, or by biomedical practitioners who have co-opted alternative techniques. I argue that Therapeutic Touch proponents have utilized several discursive strategies in presenting and arguing for their alternative healing model. These strategies surround the issues of professional legitimacy, scientific validity, and TT’s perception as religious or spiritual. Therapeutic Touch proponents manage their discourse by conforming it to orthodox biomedical discourse and by pursuing a strategy of professionalization. Through this management process, they have been able to maintain a marginal presence within biomedicine.

abstract: Thesis

abstract: Master of Arts (MA)


title: The Impact of an Educational Program on the Nursing Management of Post-operative Pain

title: The Nursing Management of Post-operative Pain

contributor:
Najm, S.
Crook, J.
Health Care Practice

subject: post-operative pain

subject: nursing management

subject: nursing management of post-operative pain

subject: management of post-operative pain

subject: nursing management

subject: impact of an educational program

subject: educational program

subject: health care practice

abstract: This study examines the influence of an educational program on the nursing assessment and management of post-operative pain. A problem-based retrospective audit was implemented to initially determine the nursing assessment and management of post-operative pain. Based on the results of the audit, educational strategies were implemented and a re-audit was carried out to evaluate the changes in nursing practice. There was evidence in the study to support the notion that nurses do not assess or manage post-operative pain effectively. The study suggested that an educational program based on the results of the problem-based audit may improve the frequency and accuracy of documentation of the assessment of pain and the documentation of the utilization of a variety of alternate approaches to relieve post-operative pain. However, the results also indicated that an educational program may not increase the frequency and dosage of analgesic administration and that nurses' perception of their nursing practice may be inconsistent with their actual practice. The study also indicated that nurses will attend educational programs if given the opportunity to participate in the development of these programs. Further studies should be carried out to examine the relationship between written documentation of assessment and management of pain and the actual assessment and management of pain by nurses, between nurses' perceptions of their clinical practice and their actual practice, and among variables environment which may affect nurses' clinical performance. Further studies should also be undertaken to determine if practice-based education programs can influence nurses' clinical practice.

abstract: Thesis

abstract: Master of Science (Teaching)


title: The Labour Feminism Takes: Tracing Intersectional Politics in 1980s Canadian Feminist Periodicals

contributor:
Dean, Amber
English and Cultural Studies

subject:
Feminism
Cultural Theory
History
Canada
Sex Work
Migrant Domestic Work
Intersectionality
Women's Labour
Race
Class
Gender
Sexuality
1980s
Feminist Political Economy

abstract: This dissertation turns to recent feminist history of the 1980s to consider feminism’s relationship to class, economics, and labour. Challenging the idea that feminism is an inclusive project, I look at how feminist ideology produces commonsense forms of racism, classism, and sexual normativity. To demonstrate this argument, I evaluate two important moments in 1980s Canadian feminism: the development of feminist political economy and the debates of the feminist sex wars. In tracing the ways in which these histories unfold to value some feminist subjects more than others, I show how feminist narratives appear cohesive through quotidian practices of exclusion. I claim that the resistance of marginalized subjects is integral to these narratives, particularly when this resistance has been made to appear invisible or absent. I first turn to feminist political economy to show how a white feminist discourse about gendered domestic labour emerged while simultaneously omitting analyses of the experiences of women of colour and migrant domestic labourers. This white feminist discourse is imbued with commonsense racism, and imagines migrant domestic workers as located elsewhere to feminism. Subsequently, I examine how the feminist sex wars pursued a line of inquiry into sexuality that privileged a framework of danger. Feminist theorizing of violence against women as intrinsic to prostitution and pornography had dire consequences for understanding sex work and the diverse women employed in the industry. In promoting a white, middle-class perspective on sexuality, feminists appropriated sex workers’ experiences of violence and sought state support for abolishing commercial sexuality, in turn contributing to the heightened state surveillance of sexual minorities. In looking to and for marginalized women’s experiences within an archive of women’s publishing, this project insists on the integral place of sex workers and migrant domestic workers within Canadian feminist labour histories.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: What is feminist labour history, and whom does it include? In a study of feminist periodicals published during the 1980s, I consider how feminist writing contributes to the project of women’s liberation. In particular, I explore debates between feminists over race, class, and sexuality. I claim that feminist periodicals offer a window into the ideas animating feminists in the 1980s, and document the ways in which women’s household labour, paid domestic work, prostitution, and pornography were taken up—or ignored—by feminists. I show how everyday practices of race, class, and sexual supremacy have created narratives where white, middle-class women’s experiences appropriate and stand in for diverse feminist histories.


title: AN INFECTION CONTROL EDUCATIONAL PROGRAM

contributor:
Schutz, Alice
Westmorland, Muriel

subject:
infection control
educational program
infection

abstract: This project describes the development of a curriculum for an infection control liaison program to be implemented in a large, regional health care institution. A curriculum module was designed to both support and challenge practising nurses to utilize critical thinking skills to guide their decision making regarding infection control practices. The author describes the process of curriculum development and presents a final curriculum product. The implementation is presented to demonstrate that the teaching of factual knowledge and skills can be integrated with higher level skills such as critical thinking, problem solving and decision making. Throughout this project, emphasis is placed on educational theory and on the practising health professional as the learner.

abstract: Thesis

abstract: Master of Science (Teaching)


title: The Effect of the Voltage-Gated Calcium Channel Blocker, Nifedipine, on Kindling and Kindling-Induced Mossy Fibre Sprouting

title: Effects of Nifedipine on Kindling and Mossy Fibre Sprouting

contributor:
Racine, Ronald
Psychology

subject:
voltage-gated calcium channel blocker
nifedipine
kindling
kindling-induced mossy fibre sprouting
mossy fibre sprouting
psychology
voltage-gated calcium channel blockers

abstract: Kindling epileptogenesis has been associated with a number of different forms of neuroplasticity in the hippocampus, including mossy fibre sprouting and an increase in both intracellular calcium and zinc. The purpose of this thesis was to determine whether interfering with the influx of calcium via the voltage gated calcium channels would interfere with kindling- induced plasticity. Both kindled and control rats were injected with either 5 or 25mg/kg of the L-type voltage gated calcium channel blocker, nifedipine, or a control vehicle, DMSO (dimethylsulfoxide). The kindled groups received a kindling stimulation twice a day for 11 days. It was revealed that both doses of nifedipine significantly increased afterdischarge duration (p<0.001) and furthermore, both doses of nifedipine were capable of significantly interfering with the rate of kindling (p<0.001). Three weeks following the last kindling stimulation, rats were perfused and brain tissue was processed according to the Timm method. The density of Timm granules, an indication of the level of intracellular zinc in the mossy fibre pathway, was quantified. The results of this analysis revealed that 25mg/kg of nifedipine is capable of significantly reducing the amount of intracellular zinc in both the IML (p<0.04) and the CA3 (p<0.01) region of the mossy fibre pathway, regardless of whether the rats had received kindling stimulations or not. These results provide support for the notion that nifedipine (5 or 25mg/kg) is an effective anticonvulsant agent. These results also suggest that, at a sufficient dose (25mg/kg), nifedipine can reduce the amount of intracellular zinc in the mossy fibre pathway in both kindled and non-kindled animals, suggesting that nifedipine may be a useful therapeutic agent for pathologies that have been associated with zinc-induced neurotoxicity.

abstract: Thesis

abstract: Master of Science (MSc)


title: Studies of Zinc and Pharmaceutical Nanoparticles

contributor:
Johari, G. P.
Materials Science and Engineering

subject:
zinc
nanoparticles
pharmaceuticals
pharmaceutical nanoparticles
materials science and engineering
zinc nanoparticles
nano-pharmaceuticals
zinc nanocrystals

abstract: This study is on thermodynamics of crystalline nanoparticles of materials. It provides measurements of the equilibrium melting point of nanocrystals of zinc in a size distribution of 30 - 120 nm, as observed by using Philips CM 12 TEM and JEOL 2010F TEM/STEM, and of the heat capacity, and melting enthalpy by using Perkin-Elmer Pyris-Diamond and TA Q100 Calorimeters. The observed melting point of zinc nanoparticles is lower than that of the bulk zinc, but their heat capacity increases and enthalpy of melting decreases. During heating, the nanoparticles oxidizes and forms zinc oxide surface layer reducing the amount and size of zinc nanocrystals. Calculations based upon the Debye theory for heat capacity show that the surface atoms on the zinc nanoparticles have ~ 55 % larger vibrational amplitude and therefore increase the entropy of the surface layer over that of the interior of the particles. During cooling, the crystallization of zinc oxide encaged zinc nanodroplets occurs in two stages, which are heterogeneous and homogeneous nucleations. As the amount of zinc nanocrystals decreases and the liquid-zinc oxide interface increases, homogeneous nucleation becomes less dominant and the two-stage crystallization merges. Nano-pharmaceuticals were produced by incorporating them in a nanoporous amorphous polymer matrix by using a technique based on diffusion method. The presence of embedded nano-pharmaceuticals is shown by their lower melting point relative to the bulk pharmaceuticals and by peak-broadening of x-ray diffraction, which shows that their size lies in 70 - 100 nm range. Although no phase inversion between allotropic forms of the pharmaceutical was observed, a sample calculation for polymorphs of tin shows that such phase inversion should occur at a smaller particle size at a lower temperature. In general, these findings show the effects of the increase in the surface energy relative to bulk energy of nanoparticles, and the consequent differences between the properties of their surface atoms relative to the interior atoms.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Instruments for the Energy: Reiki, Authenticity, and the Construction of Meaning

title: Instruments for the Energy: Reiki, Authenticity, and Meaning

contributor:
Badone, Ellen
Religious Studies

subject:
Reiki
instruments for the energy
energy
authenticity
construction of meaning
meaning
religious studies
authentic

abstract: This thesis explores the narratives of individuals in southern Ontario who have adopted the practice of Reiki. Focusing on the narratives of Reiki Masters and practitioners, this thesis examines the relationships between illness, healing, and authenticity within the larger framework of energy work. The overarching goal of this thesis is to demonstrate the way in which Reiki Masters and practitioners draw on their experiences of Reiki to create meaning. As practitioners’ narratives reflect, illness is understood as multivalent in nature, and thereby may be physical, emotional and/or psychological, and spiritual. As these narratives show, illness becomes a framework through which individuals can interpret their experience. Often described as a conduit for the universal energy, the Reiki practitioner and his or her role are central to understanding the relationship between Reiki and healing. I propose that Reiki can be interpreted as a form of religious healing. Following Csordas’ (1983, 2002) “rhetoric of transformation,” I propose that Reiki provides a means through which practitioners become able to re-order experience. Like illness, Reiki Masters and practitioners also understand healing in multiple ways, including physical, emotional, psychological, and spiritual. Finally, I explore the increased interest in Reiki in the West and the importance to practitioners of the relationship between Reiki and Japanese culture. Through an analysis of Reiki practitioners’ narratives, I will demonstrate that the nature of their experience and their interpretations of that experience influences their notions of what constitutes “authentic” or “real” Reiki. Ultimately, it is a fluid and flexible construction of the “authentic” which allows practitioners the space in which to interpret for themselves their own experiences with Reiki.

abstract: Thesis

abstract: Master of Arts (MA)


title: Multi-label Classification and Sentiment Analysis on Textual Records

contributor:
Chen, Jun
Electrical and Computer Engineering

subject:
NLP
sentiment analysis
multi-label classification
machine learning
deep learning

abstract:
In this thesis we have present effective approaches for two classic Nature Language Processing tasks: Multi-label Text Classification(MLTC) and Sentiment Analysis(SA) based on two datasets.
For MLTC, a robust deep learning approach based on convolution neural network(CNN) has been introduced. We have done this on almost one million records with a related label list consists of 20 labels. We have divided our data set into three parts, training set, validation set and test set. Our CNN based model achieved great result measured in F1 score. For SA, data set was more informative and well-structured compared with MLTC. A traditional word embedding method, Word2Vec was used for generating word vector of each text records. Following that, we employed several classic deep learning models such as Bi-LSTM, RCNN, Attention mechanism and CNN to extract sentiment features. In the next step, a classification frame was designed to graded. At last, the start-of-art language model, BERT which use transfer learning method was employed.
In conclusion, we compared performance of RNN-based model, CNN-based model and pre-trained language model on classification task and discuss their applicability.

abstract: Thesis

abstract: Master of Science in Electrical and Computer Engineering (MSECE)

abstract: This theis purposed two deep learning solution to both multi-label classification problem and sentiment analysis problem.


title: INVESTIGATING THE PARAMETERS OF PRE-/POST-CONDITIONING ON  HUMAN-DERIVED CANCER CELLS

contributor: Radiation Sciences (Medical Physics/Radiation Biology)

subject:
Radiation
Biology
Cell culture
Cancer
Radiobiology
p53
gamma radiation
post-conditioning
biophoton
radiation detection

abstract: There is a large amount of interest and research currently going into studying the effects of low dose radiation on humans, and bridging the gap with the data from the effects of high dose radiation. Much work is to be done to understand low dose exposures such as from medical treatments and those who work with or around radiation. Two popular and widely known examples of low-dose phenomena are the radiation induced bystander effects and the radioadaptive response (RAR). This research involves the study of the impact of a low dose of radiation that is administered several hours after a high – even fatal – dose is given, which contrasts the traditional RAR where a low priming dose is given before a high dose and can lead to increased cell survival. Many different parameters were checked to see if cell survival can be enhanced or diminished depending on the stage of the cell cycle, cell growth conditions, and cell profiling differences in protein function (namely the TP53 gene). Additionally, the post-conditioning response was contrasted to see if it was possible to see any effects from the newly emerging area of bystander signalling, UV BioPhotons, would be present in cell lines that either did or did not exhibit a post-conditioning effect. It was shown that post-conditioning has a protective effect on survival of the cells in certain dose ranges and certain cell lines. The post-conditioning effect also appears to be stronger in magnitude than the classic RAR. No relationship between gamma-induced biophoton signalling and post-conditioning was observed, nor is it certain whether an acute gamma-field can induce significant UV biophoton damage. This thesis is aimed to explore the various parameters by which post-conditioning effects occur on various Human cancers.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: This research looks at the effects of radiation on cells. More specifically, how do low doses of radiation affect cells after they have already been treated with higher doses of radiation. Moreover, can cells communicate through non-physical methods, such as through invisible light? The research focuses primarily on cancer cells and their responses to varying doses of radiation treatments.


title: The Effect of Hinged Ankle Foot Orthoses on the Oxygen Cost of Walking in Children with Spastic Diplegic Cerebral Palsy

title: AFO and the Oxygen Cost of Walking in Cerebral Palsy

contributor:
Bar-Or, Oded
Human Biodynamics

subject:
hinged ankle foot orthoses
oxygen cost
spastic diplegic cerebral palsy
cerebral palsy
oxygen cost of walking
children
human biodynamics
orthoses
ankle foot orthoses
AFO

abstract: Children with cerebral palsy (CP) have a higher than normal O2 uptake (VO2) during walking. While various interventions are used to improve locomotion, little is known about their effect on the metabolic and cardiopulmonary cost of walking. We therefore assessed the effects of one popular intervention, hinged ankle foot orthoses (AFO), on cardiopulmonary and metabolic variables during 2 min of steady state treadmill walking at three speeds: 3 kph, comfortable walking speed (CWS) and fast walking speed (FWS). We also assessed the effect of these braces on comfortable and maximum ground walking speed and on gross motor abilities using the Gross Motor Function Measure. Ten children with spastic diplegic CP (9.01 years ± 2.10) who habitually used hinged AFO participated. Not all children could walk at all speeds on the treadmill however, and some cardiopulmonary and metabolic data on three children were missing due to equipment failure. We performed an ANOVA on data for children who walked at 3 kph and CWS (n=8 for heart rate (HR); n=9 for pulmonary ventilation and metabolic variables) and a t-test on data at FWS (n=9 for HR, n=8 for pulmonary ventilation and metabolic variables). When children wore AFO, absolute VO2 was reduced by 4.6% at 3 kph and by 4.1% at FWS, and absolute VO2 per metre walked by 4.6% and 4.4% at the same speeds, respectively. Adjusting VO2 for body mass, or for resting VO2 or calculating energy expenditure in kJ, revealed the same pattern. Pulmonary ventilation was lower with AFO on by 7.17%, but only at 3 kph. AFO did not affect gross motor abilities. Nor did it affect HR, or the respiratory exchange ratio at any speed, nor any physiologic variable at CWS. We suggest the lower O2 cost may reflect an increase in stability and a corresponding decrease in coactivation of lower limb antagonistic muscles.

abstract: Thesis

abstract: Master of Science (MSc)


title: Vegetation Controls on Evaporation from a Subarctic Willow-Birch Forest

contributor:
Rouse, W. R.
Geography

subject:
vegetation controls on evaporation
evaporation
vegetation
subarctic
willow-birch
willow-birch forest
forest
willow
birch
vegetation controls
geography
Subarctic

abstract: Continuous measurements of the energy and radiation balance were made during the 1991 growing season over a dwarf willow-birch forest located near Churchill, Manitoba. The ecological setting is described in terms of both the nature of the substrate and the morphology and distribution of the plant species. Intensive measurements of stomatal conductance and xylem pressure potential for several species were taken on three fair weather days. These represented a wide range of air temperatures and leaf-to-air vapour pressure deficits and allowed the quantification of the surface-atmosphere interactions. The very dynamic and important role of the vegetation in the evaporative process is illustrated. The willow-birch forest consists of six main species which have colonized the recently emerged coastline. There is a wide range in the plant height, rooting networks, and above-to-below ground plant mass. A mature leaf area index of 0.81 m^2 m^-2 was reached within 15 days after the onset of growth. The substrate consists of a 20 cm moderately saline organic layer situated on top of sand. Soil moisture was high, with at least some of the roots of all plants residing within the saturated zone throughout the growing season. The influence of the vegetation on both the radiation and energy balance is illustrated by partitioning the growing season into growth, mature and senescence periods. A strong relationship between surface albedo and vegetation growth indicates that the canopy is more effective in reflecting than in trapping radiation. As the canopy matures, the addition of transpiration to the overall evaporation dramatically increases the magnitude of the latent heat flux at the expense of the sensible heat flux. A sensitivity analysis indicates that evaporation is highly sensitive to the canopy resistance. The sensitivity of evaporation to canopy resistance, in turn, is a function of the ratio of canopy-to-aerodynamic resistance. Strong seasonal and diurnal trends are shown in the sensitivity of evaporation to net radiation, canopy resistance, and aerodynamic resistance. Diurnal stomatal conductance measurements indicate that some species show a pronounced midday stomatal closure. A conceptual model is developed which attributes this behaviour to differences in the sensitivities to the leaf-to-air vapour pressure deficit. A non-linear boundary line analysis of stomatal conductance indicates species-specific responses to irradiance, air temperature, leaf-to-air vapour pressure deficit, and xylem pressure potential. The results of the boundary line analysis are coupled with a modified version of the Penman-Monteith combination model. The model predicts evaporation accurately when the canopy is mature, and indicates that 80% of the evaporation originates from the plants (transpiration). The model is used to examine the potential effects of species composition and climate change on evaporation. This illustrates the important and variable role that vegetation can play in determining responses to climate change.

abstract: Thesis

abstract: Master of Science (MSc)


title: Statistical Analysis of Asthma Hospitalization Incidences in Canadian Children

contributor:
Viveros-Aguilera, Román
Statistics

subject:
statistical analysis
asthma
hospitalization
children
Canada
Canadian children
hospitalization incidences
asthma hospitalization
statistics

abstract: Asthma is the leading chronic disease of children in industrialized countries. In Canada, it is the most common cause of hospital admissions in children. Data were assembled for all asthma hospitalizations in Canada from 1990 to 2000 by the Canadian Institute for Health Information (CIHI). The annual cycles of asthma hospitalization among Canadian children from 1990 to 2000 were compared. For every year, region and latitude, asthma hospitalizations were lowest in July and August followed by a major peak in September then a rapid decline. Contingency table analyses were done to examine the homogeneity of the distributions of asthma hospitalization counts for the factors age, gender, region and latitude groups. Age, region and latitude groups were found to be significantly different with respect to their distribution of asthma counts. However, the distributions of asthma hospitalization counts did not differ significantly for gender. A nonlinear least squares model was fitted to the asthma hospitalization data for weeks 30 to 42. The primary objective was to obtain estimates of the parameter that describes the timing of the September peak. Next, a likelihood ratio test was done to assess the homogeneity of the September peaks for the factors age, gender, latitude and region. We found that, apart from gender, the September peaks were significantly different. Furthermore, the annual cycle of asthma hospitalization for children aged 2 to 4 was identical to that of children aged 5 to 15 except the peak in hospitalization for 2 to 4 year olds occurred on average 2 days after the older children. We suspect that the increase prevalence of and exposure to viral infections, exposure of school-aged children to allergens at school and the transmission of these factors to younger siblings are responsible for the September asthma epidemic. A Quasi-Poisson log-linear model was also fitted to the data to assess jointly the effects of age, gender, latitude, year and risk group size. The data were overdispersed, after accounting for overdispersion, we found that age, gender, latitude, year and the interactions between age and gender, age and latitude and gender and latitude were significant in explaining the data. Surprisingly, time had a negative effect suggesting a tendency to decline in the number of asthma incidences requiring hospitalization over the years.

abstract: Thesis

abstract: Master of Science (MSc)


title: "Danger" and the "Dangerous Case": Divergent Realities in the Therapeutic Practice of Traditional Birth Attendants in Garhwal, India

title: Divergent Realities in the Practice of Birth Attendants in India

title: "Danger" and the "Dangerous Case": Divergent Realities in the Therapeutic Practice of the TBA in Garhwal, India

title: "Danger" and the "Dangerous Case": Divergent Realities in the Therapeutic Practice of the Traditional Birth Attendant in Garhwal, India

contributor:
Glanville, Edward
Anthropology

subject:
India
birth attendants
Birth Attendants
Traditional Birth Attendants
traditional birth attendants
TBAs
TBA
Garhwal
India
Garhwal, India
anthropology
therapeutic practice
danger
dangerous case
"danger"
"dangerous case"
dais
Birth Attendant
birth attendant
traditional birth attendant
Traditional Birth Attendant

abstract: Traditional Birth Attendants (TBAs) are the primary health care providers for women at the time of childbirth in many parts of the world. In India, particularly in remote areas such as Garhwal, these women play a key role in maternal health. Training programmes for TBAs can lead to dramatic reductions in neonatal mortality as well as in maternal morbidity and mortality, due to improved hygienic practices at the time of delivery. Yet training programmes for TBAs often lack sociocultural relevance, and fail to incorporate an understanding of the TBAs' perceptions of the process of pregnancy and delivery. Understanding more about the role of the TBA as a diagnostician and a decision-maker within a given sociocultural context can make such training programmes more culturally congruent. This research report describes the way in which TBAs (dais) in Garhwal interpret obstetrical complications, and how they make decisions regarding the need for cosmopolitan medical care. TBAs in Garhwal interpret obstetrical complications using a variety of explanatory models, arising from an understanding of health and illness which shows influences of Vedic, Ayurvedic, folk and cosmopolitan medical models. These explanatory models often led to a perception of "danger” and the "dangerous case" which is widely divergent from the cosmopolitan medical model. Specific areas are identified where the dais' interpretation of "danger" was particularly divergent from the cosmopolitan medical model. These areas of conceptual conflict result in diagnoses and treatment procedures which can lead to significant delays in the woman receiving needed cosmopolitan medical care. The third stage of action-research process is the development of a participatory training programme, in which the TBA is an active participant. The aim of the training programme is to move towards a shared perception of risk regarding major obstetrical complications.

abstract: Thesis

abstract: Master of Arts (MA)


title: The Antiferromagnetic Quantum Critical Metal: A nonperturbative approach

contributor:
Lee, Sung-Sik
Physics and Astronomy

subject:
Metals
Non-Fermi Liquids
Quantum Criticality
Quantum Field Theory
Renormalization Group

abstract: PhD Thesis

abstract: The superconductivity in heavy-fermion compounds, iron pnictides and  cuprates has been intensively studied for over thirty years. Amongst some of these materials, the common denominator is the presence of strong antiferromagnetic fluctuations in their normal state, signaling an underlying quantum phase transition between a paramagnetic metal and a metal with antiferromagnetic long-range order. Although the quantum critical point is experimentally inaccessible due to the presence of superconducting order, it determines the physical properties of the normal state of the metal in a wide range of temperatures. In this thesis we study the low-energy theory for the critical metallic state that arises at the aforementioned quantum critical point. We present a nonperturbative study of the theory in spatial dimensions between two and three. We  pay special attention to two dimensions where we show that our physical predictions are in qualitative agreement with experiments in electron-doped cuprates. We further develop a field theoretic functional renormalization group scheme that is analytically tractable. It provides a general framework to study the low-energy theory  of metallic states with or without a quasiparticle description. Within this formalism we characterize the single-particle properties of the antiferromagnetic quantum critical metal. This allows one to study  the superconducting instability triggered by critical antiferromagnetic quantum fluctuations quantitatively.

abstract: Thesis

abstract: Doctor of Science  (PhD)


title: A Comparison of the Effectiveness of Videotape (Closed Circuit Television) versus Live Group Infant Care Classes, as a Teaching Tool for Post-Partum Mothers

title: CCTV vs. Classes as a Teaching Tool for Post-Partum Mothers

contributor:
Richardson, Jack
Ellis, Patricia
Health Care Practice

subject:
infant care
infant
infant care classes
live group
closed circuit television
CCTV
videotape
classes
class
post-partum
mothers
teaching tool
teaching tools
health care practice
live class groups
live class group
live groups

abstract: This study is designed to assess the effectiveness of closed-circuit television (CCTV) as a post-partum teaching tool using an interactive problem-solving approach, compared with conventional group classes, in fostering the acquisition of skills and knowledge around baby care. A second primary objective is to determine the level of satisfaction of respondents with both approaches to post-partum education. An extensive discussion of the theoretical basis for the proposal is presented, drawing upon and synthesising concepts from the literature of Sociology, Education and Health Sciences. The conceptual model (Sword 1990) represents a synthesis of Mezirow’s (1978) theory of the transformation of meaning perspective with D’Zurilla’s (1986) cognitive-appraisal approach to the acquisition of new knowledge. In addition, adult learning principles are applied to the selected teaching strategies to identify optimal conditions of learning (Zemke and Zemke 1988). A two-group cohort design was used for randomisation, and the data collected was subjected to both quantitative and qualitative analysis. Two measures of learning were not significantly different for the videotape and live class groups. Statistically significant differences were identified between the groups in the attitude measures of convenience and ease of understanding. There was also a measurable difference in levels of satisfaction with the different approaches used. However, the results of this study suggest that combining an interactive, problem-solving approach to post-partum education with CCTV, is no more effective than live group classes in achieving knowledge acquisition for new mothers. CCTV can be used to address the basic and repetitive aspects of patient education and it appears to be effective for short-term knowledge gain. Several issues for further study are proposed in relation to the planning and implementation of alternative approaches to conventional post-partum teaching, as well as the design of future televised patient education programmes.

abstract: Thesis

abstract: Master of Science (MSc)


title: Green Practices and Technologies for Sustainable Communities

contributor:
Korol, Robert
Civil Engineering

subject:
green practices
green technologies
sustainable communities
green practices and technologies
civil engineering
sustainable development

abstract: In 1987, Gro Harlem Bruntland formally introduced and popularized the concept of sustainable development. She defined it as being “development that meets the needs of the present without compromising the ability of future generations to meet their own” (World Commission on Environment and Development, 1987). Several cities, including the City of Hamilton have adopted certain environmental practices and technologies in an endeavor to improve their level of urban sustainability and achieve Bruntland’s goal of sustainable development. These practices include the support of individuals and city organizations that investigate new sustainable design alternatives for current infrastructure development. Such sustainable alternatives include the consumption of locally grown produce to avoid the detrimental effects associated with the transportation of imported foods via transport trucks, the installation of Rooftop Gardens as a viable option of ‘greening’ modern urban landscapes, and the construction of R-2000 Homes to reduce energy consumption rates and decrease the levels of harmful emissions that would normally be produced by conventional homes. The implications and/or benefits associated with any of the aforementioned designs were calculated using an environmental assessment tool developed by a professor at the University of British Columbia: Ecological Footprint (EF) Analysis. The final results of this study indicated that consuming locally grown produce, installing Rooftop Gardens, and living in R-2000 homes have the potential to enhance the state of the environment by improving air quality, reducing energy consumption, reducing water consumption, improving storm water retention, or by enhancing the biodiversity of a city’s landscape. However, in order to reap the benefits of any or all of the above ‘green’ practices or technologies and begin to establish a sustainable community, the fundamental doctrines that have influenced modern development practices, particularly those that place economic progress in front of the conservation and preservation of the environment, will need to be changed.

abstract: Thesis

abstract: Master of Engineering (ME)


title: Stress Dependent Behaviour of InGaAsP Semiconductor Diode Lasers

contributor:
Cassidy, D. T.
Engineering Physics

subject:
stress dependent
InGaAsp
diode laser
semiconductor diode laser

abstract:
The effects of tension and compression applied to unbonded InGaAsP
semiconductor diode lasers have been studied. A theoretical calculation of the stress
distribution within the laser and an analysis of the effect of strain on optical gain in
semiconductors is presented. The observed dependence of threshold, wavelength,
and polarization of the laser output on the applied stress is explained in terms of the
strain dependence of the valence-band wavefunctions.
The polarization behaviour is found to be related to thermal stress
and the structure of the device. A technique has been developed to measure the
thermal stress induced by current heating at the 105 dynes/cm2 level.
The effect of stress on the below threshold behaviour of the lasers was
investigated. The results are consistent with the strain dependence of the TE and
TM mode gains.

abstract: Thesis

abstract: Master of Engineering (ME)


title: Retention of the Incompletely Learned Avoidance Response: The Effects of Handling and Location During the Intersession Interval

title: Retention of the Incompletely learned Avoidance Response

contributor:
Kamin, L. J.
Psychology

subject:
incompletely learned avoided response
handling and location
intersession interval

abstract:
The retention curve of an incompletely learned avoidance response was investigated, employing rats in a shuttlebox situation. Subjects were given a 15 trial re-learning
session 0, 1/2, 1 or 24 hours after original acquisition. Three treatment groups were tested at these intervals: a not-handled group which remained in the shuttlebox during the intersession interval, a handled group which remained in the shuttlebox during the intersession interval, and a group which was returned to a living cage. All treatment groups produced a monotonically decreasing curve as a function of intersession interval. Handling produced a decrement on performance at 0-hour intersession interval; location showed no
effect. Results were interpreted in terms of the warm-up decrement and the effects of handling on the arousal of fear.

abstract: Thesis

abstract: Master of Arts (MA)


title: 3D Surface Reconstruction from Multi-Camera Stereo with Disturbed Processing

contributor:
Capson, David
Electrical and Computer Engineering

subject:
3D surface reconstruction
multi-camera stereo
distributed processing

abstract: In this thesis a system which extracts 3D surfaces of arbitrary scenes under natural illumination is constructed using low-cost, off-the-shelf components. The system is implemented over a network of workstations using standardized distributed software technology. The architecture of the system is highly influenced by the performance requirements of multimedia applications which require 3D computer vision. Visible scene surfaces are extracted using a passive multi-baseline stereo technique. The implementation efficiently supports any number of cameras in arbitrary positions through an effective rectification strategy. The distributed software components interact through CORBA and work cooperatively in parallel. Experiments are performed to assess the effects of various parameters on the performance of the system and to demonstrate the feasibility of this approach.

abstract: Thesis

abstract: Master of Engineering (ME)


title: The Evaporation of Manganese from Liquid Iron Under Reduced Pressures in the Temperature Range 1320C to 1810C

contributor:
Ward, R. G.
Chemical Engineering

subject:
evaporation
manganese
liquid iron
reduced pressure
temperature range

abstract:
This thesis presents a review of the theory of evaporation of pure substances with respect to kinetic and mechanistic models. These concepts are applied to multi-component evaporation and a model for the evaporation of solute atoms from a solvent is postulated. The evaporation
experiments were performed on Fe 1% Mn melts at a constant pressure of approximately 10 microns over a temperature range of 1320° to 1810°C. The correlation between the experimental results and the expected theoretical results is discussed thoroughly in terms of surface control and diffusion control.

abstract: Thesis

abstract: Master of Engineering (ME)


title: Multivariate Image Analysis for Real-Time Process Monitoring

contributor:
MacGregor, J. F.
Chemical Engineering

subject:
multivariate image analysis
real-time process monitoring

abstract: In today’s technically advanced society the collection and study of digital images has become an important aspect of various off-line applications that range from medical diagnosis to exploring the Martian surface for traces of water. Various industries have recently started moving towards vision based systems to monitor several of their manufacturing processes. Except for some simple on-line applications, these systems are primarily used to analyze the digital images off-line. This thesis is concerned with developing a more powerful on-line digital image analysis technique which links the fields of traditional digital image processing with a recently devised statistically based image analysis method called multivariate image analysis (MIA). The first part of the thesis introduces the area of traditional digital image processing techniques through a brief literature review of three of its five main classes (image enhancement, restoration, analysis, compression, & synthesis) which contain most of the commonly used operations in this area. This introduction is intended as a starting point for readers who have little background in this field, and as a means of providing sufficient details on these techniques so that they can be used in conjunction with other advanced MIA on-line monitoring operations. MIA of multispectral digital images using latent variable statistical methods (Multi-Way PCA / PLS) is the main topic covered by the second part of this thesis. After reviewing the basic theory of feature extraction using MIA for off-line analyses, a new technique is introduced that extends these ideas for image analyses in on-line applications. Instead of directly using the updated images themselves to monitor a time- varying process, this new technique uses the latent variable space of the image to monitor the increase or decline in the number of pixels belonging to various features of interest. The ability to switch between the images and their latent variable space then allows the user to determine the exact spatial locations of any features of interest. This new method is shown to be ideal for monitoring interesting features from time-varying processes equipped with multispectral sensors. It forms a basis for future on-line industrial process monitoring schemes in those industries that are moving towards automatic vision systems using multispectral digital imagery.

abstract: Thesis

abstract: Master of Engineering (ME)


title: Time-Domain Simulation of Semiconductor Laser in Fiber-optic Communication Systems

contributor:
Huang, Wei-ping
Li, Xun
Electrical and Computer Engineering

subject:
time-domain simulation
semiconductor laser
laser
fiber-optic
communication systems
electrical and computer engineering
electrical engineering
computer engineering
fiber-optic communication systems

abstract: As the light source, semiconductor laser diodes play an important role in the fiber-optic communication systems. The main function of a laser diode is to convert signals from the electrical domain to the optical carriers so that they can be transmitted through an optical fiber. Modeling and simulation of directly modulated laser diodes are necessary for understanding and prediction of their performance in fiber-optical communication links. The alternatives based on a comprehensive experimental evaluation are normally costly and time consuming. This is particularly true for systems running at high bit-rate such as the 10Gb/s transmission systems that are used in tele and data communication applications. This thesis presents a modeling and simulation study for directly modulated laser diodes for high-speed fiber-optical communication systems. The work is based on the conventional rate equation model used as the governing equation for the simulation of the behavior of semiconductor lasers. In modeling of the system performance, each device is treated as a symbolic node that takes input signal and generates output signal all in time domain. For the semiconductor lasers, the original signals in electrical domain are taken as the input while the modulated lights in optical domain are as the output. The rate equations then link the output to the input. For any given time domain signal input, the modulated light (power and wavelength) as the output is calculated through the solutions of the rate equations. In seeking for the solution to the rate equations, we utilized a numerical approach to solve the rate equations which are a system of coupled nonlinear ordinary differential equations where analytical solution does not generally exist. In this work, a comprehensive study on the behavior of semiconductor lasers has been performed through static and dynamic analyses of the rate equations. The noise characteristic is also examined as it may become a major concern in some applications for the noise of the directly modulated laser transmitter may cause degradation to the signals and therefore lead to system penalty. Further, the numerical models and simulators developed for semiconductor lasers are incorporated into a general simulation platform on which similar models and simulators for other optoelectronic and optical components are connected to form a system-level simulator for point-to-point multiple channel fiber-optical communication links. This platform is capable of handling different system configurations with different component selection options. It simulates the time domain waveform in any point along the signal transmission path following a strict data-flow approach; i.e., the simulation is performed sample-by-sample on “real time” rather than frame-by-frame at “flush” mode. Finally, the simulation results, both on the device level and on the system level, have been compared with the experimental data and the results from other models in literature and found qualitative agreement.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Evaluation of Automatic Incident Detection Systems Using the Automatic Incident Detection Comparison and Analysis Tool

contributor:
Hall, F. L.
Abdulhai, B.
Engineering

subject:
automatic incident detection algorithms
AID comparison
AID analysis tool

abstract: This thesis presents a new testbed for Automatic Incident Detection (AID) systems that uses real-time traffic video and data feeds from the Ministry of Transportation, Ontario (MTO) COMPASS Advanced Traffic Management System (ATMS). This new testbed, termed the AID Comparison and Analysis Tool (AID CAAT), consists largely of a data warehouse storing a significant amount of traffic video, the corresponding traffic data and an accurate log of incident start/end times. An evaluation was conducted whereby the AID CAAT was used to calibrate, and then analyze the performance of four AID systems: California Algorithm 8, McMaster Algorithm, the Genetic Adaptive Incident Detection (GAID) Algorithm and the Citilog - VisioPAD. The traditional measures of effectiveness (MOE) were initially used for this evaluation: detection rate (DR), false alarm rate (FAR), and mean time to detection (MTTD). However, an in-depth analysis of the test results (facilitated by the AID CAAT) revealed the need for two additional MOEs: False Normal Rate and Nuisance Rate. The justification and sample calculations for these new MOEs are also provided. This evaluation shows the considerable advantages of the AID CAAT, and also suggests the strengths and weaknesses of the AID systems tested.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: The Implementation of a Standard Computer Graphics Package - Graphical Kernel System

contributor:
Fleming, W. H.
Computation

subject:
implementation
standard computer graphics package
graphical kernel system

abstract: Computer graphics is a field whose time has come. In the past, it was an esoteric specialty involving expensive display hardware and idiosyncratic software. Recently, hardware has become more readily available, and efforts have been made to develop graphics software standards, which help make graphics programming rational and straightforward. The Graphical Kernel System (GKS) is rapidly gaining acceptance as a worldwide standard for computer graphics. The International Standards Organization (ISO) is in the final stages of converting GKS from its current status as a Draft International Standard (DIS) to an International Standard. This report presents an overview of GKS and also discusses a subroutine library, that has been developed for use at McMaster University and is equivalent to ”0a" GKS (the lowest level of GKS). This library, called GKSLIB, is written in FORTRAN 77, and could be used by a programmer to support a wide range of two-dimensional, passive graphics applications.

abstract: Thesis

abstract: Master of Science (MS)


title: A General Approach to Design Automation

contributor:
ElMaraghy, Hoda
Mechanical Engineering

subject:
general approach
design automation

abstract: This thesis developed a domain independent “shell system for routine mechanical design”. This shell is used to produce domain specific design systems by simply placing domain- related knowledge into it. A general “design model”, which is an informal description of the mechanisms behind the design process, has been implemented. The design model is established based on the “characteristics and mechanisms common in routine mechanical design activities”. By examining particular design examples, it is concluded that the routine design activities have: 1) a “common design procedure” from specification recognition to detailed design; 2) “common mechanisms” to determine parameters and the like; and 3) “common knowledge formats” to express design knowledge. Only “detailed design knowledge” is specific to each domain, but can be represented in common knowledge formats. The “model” and its implementation, the shell system, describe the design process in four stages: specification development, synthesis, analysis and non-functional considerations. The synthesis achieves rough structural configurations by following the “configuration decomposition approach” which is derived from the well-developed configuration decomposition patterns in the routine design, and which uses function-to-configuration, configuration decomposition and function-checking relations. In the analysis stage, configuration parameters are determined by design relations which are represented by “design slices” written in the form of “basic description elements”. The analysis knowledge is organized in a multilevel structure from lower levels of basic description elements, design slices, to upper levels of “design procedures” and “knowledgeable configuration units”. Design slices are classified as “solving slices” and “checking slices” responsible respectively for determining parameters and ensuring that checking criteria among parameters are met. A design procedure is a pile of design slices and determines a set of parameters since design relations are used in groups. The uppermost level consists of knowledgeable configuration units. They organize design procedures, parameter sets and configuration decomposition patterns under a configuration. The reasoning process in analysis is decentralized through a number of “interpreters” which handle various tasks such as choosing a design procedure. The non-functional design aspects are considered in the design relations and are incorporated into the analysis. The shell system provides general design knowledge representation formats and general reasoning mechanisms. It is implemented on a SUN workstation using KEE which provides object-oriented programming and rule reasoning facilities. Connection between design components is dealt with using partial configurations and constraints which define the relationships between configurations and partial configurations involved in a connection. The iteration process caused by dependency among parameters is handled using the failure design procedures, that is, if a checking relation is not satisfied, a failure design procedure is called to modify some parameters at the early design stage. The geometry aspect is implemented parametrically based on an existing feature-based modelling system (IPDM). Two specific design systems: a cam system and a bolted flange system, have been developed based on the shell. Both accept given specifications, and output configurations with parameters and graphic display. The development process of these two systems is simple and efficient; and design results are satisfactory. These examples illustrated the versatility and effectiveness of the developed approach to routine mechanical engineering design activities. The major feature of this work is the explicit descriptive style in representing the design knowledge. The domain independent shell approach enhanced by this feature greatly simplifies the development of domain specific knowledge bases.

abstract: Thesis

abstract: Master of Engineering (ME)


title: Materials Patterning with an Excimer Laser

contributor:
Preston, J.S.
Engineering Physics

subject:
materials patterning
excimer laser
laser
engineering physics

abstract: An investigation into the feasibility of laser ablation as a material selective removal technique was conducted. Polyimide films approximately 1 micron thick were prepared on silicon wafers. The ablation rate of these films as a function of laser fluence was studied. It was observed that a minimum threshold fluence of 67 +/- 6 mJ/cm^2 had to be surpassed to achieve a significant material removal rate. In addition to polyimide, the removal and damage characteristics of aluminum films were also examined. These films, which ranged in thickness from 50 to 1000 nm, were deposited on polyimide coated silicon wafers. It was found that the best results were produced by a single shot removal technique, with the quality of the hole dependent upon the incident fluence. At lower fluences, removal ceased and only physical damage to the film occurred. In an attempt to characterize this damage, the electrical resistance of small aluminum wires was monitored as they were exposed to laser pulses. It was found that a change in the resistance of the wires could not be detected prior to the onset of visible damage. Once the optimal removal fluences for both materials were determined, a multilayer consisting of an aluminum layer "sandwiched" between two polyimide layers was prepared. By varying only the incident fluence, it was possible to remove upper layers without removing or damaging the underlying ones. In a related experiment, the possible incubation of polyimide by low fluence laser pulses was also examined.

abstract: Thesis

abstract: Master of Engineering (ME)


title: THE IMPACT OF MATERNAL AND/OR NEWBORN GENETIC RISK SCORES ON MATERNAL AND NEWBORN DYSGLYCEMIA

title: MATERNAL AND NEWBORN GENETIC RISK SCORE AND DYSGLYCEMIA

contributor:
Anand, Sonia
Health Research Methodology

subject:
gestational diabetes
type 2 diabetes
polygenic risk score
south asian
genome wide association study

abstract:
Background:  South Asians are at an increased risk of developing dysglycemia during and after pregnancy. In pregnant women, dysglycemia often develops in the form of gestational diabetes mellitus (GDM), which may predispose their newborns to adverse health outcomes through abnormal cord blood insulin levels. However, reasons for the elevated risk of dysglycemia in South Asians have not been extensively studied. Genetic factors may contribute to the heritability of GDM and abnormal cord blood insulin levels in South Asians.

Objectives: The objectives of this thesis were to test the association of:
1) A type 2 diabetes polygenic risk score with GDM in South Asian pregnant women from the South Asian Birth Cohort (START);
2) maternal and newborn insulin-based polygenic risk scores with cord blood insulin and glucose/insulin ratio in South Asian newborns from START

Methods: Three polygenic risk scores were created to test their association with participant data (N=1012) from START. GDM was defined using cut-offs established by the Born in Bradford cohort of South Asian women. The type 2 diabetes polygenic risk score was created in 832 START mothers and included 35,274 independent variants. The maternal and newborn insulin-based polygenic risk scores were created in 604 START newborns and included 1128017 independent variants. Univariate and multiple logistic and linear regression models were used to test the associations between the polygenic risk scores and dysglycemia outcomes.

Results: The type 2 diabetes polygenic risk score was associated with GDM in both univariate (OR: 2.00, 95% CI: 1.46-2.75, P<0.001), and multivariable models (OR: 1.81, 95% CI: 1.30-2.53, P<0.001). The maternal insulin-based polygenic risk score was not associated with cord blood insulin or cord glucose/insulin ratio. However, the newborn insulin-based polygenic risk score was associated with cord blood insulin in a multivariable model adjusted for maternal insulin-based polygenic risk score (β = 0.036, 95% CI: 0.002 – 0.069; P=0.038 among other factors.

Conclusion: A type 2 diabetes polygenic risk score and a newborn insulin-based polygenic risk score may be associated with maternal and newborn dysglycemia.

abstract: Thesis

abstract: Master of Science (MSc)

abstract:
Background: South Asians are approximately two times more at risk for developing gestational diabetes mellitus (GDM) compared to white Caucasians. Genetic factors may contribute to this elevated risk. Polygenic risk scores (PRSs), which combine the effects of multiple disease loci and variants associated with the disease into one variable could be useful in further understanding how GDM develops in South Asians.

Methods: Data from the South Asian Birth Cohort (START) was used to test the association of three PRSs with the outcomes of interest.

Results: The type 2 diabetes PRS was independently associated with GDM. The insulin-based maternal PRS was not associated with cord blood insulin but the insulin-based newborn PRS was independently associated with cord blood insulin. However, neither the insulin-based maternal nor newborn PRS was associated with cord blood glucose/insulin ratio.

Conclusion: The PRSs suggests a possible genetic component, which contributes to abnormal glycemic status development in South Asian mothers and their newborns.


title: Estimates of Transportation Energy Savings with Transportation Management Measures for Varying City Size

contributor: Civil Engineering and Engineering Mechanics

subject:
transportation energy savings
transportation management measures
varying city size

abstract:
Since the early 1970's, fuel consumption in the transportation sector has been one of the major issues facing planners trying to conserve energy. Generally, fuel consumption is influenced directly by the number of vehicles, the distance travelled, the operating speed and the overall population of city. Traffic engineers spent a great deal of time solving such a problem sometimes by introducing the concept of traffic management, the different actions and strategies that reduce the fuel consumption and some other times by estimating the energy saving to evaluate the effectiveness of these actions. Despite best efforts, energy savings
estimation have shown wide fluctuations. This study provides a preliminary Investigation of the impact of city size, in the medium range, on potential energy savings accrued due to implementation of Transportation Energy Management Measures (TEMM's). The data sources used includes the energy savings for each of five city size groups, subjected to 23 TEMM's. These data were rearranged and regressed over city size by using the CURFIT technique.
Formulae were derived for each of the TEMM's. For the purpose of verification, the Community Benefits Analysis program (CBA) was applied to test some of the obtained results. It is thus concluded that the resulting energy savings, using the regressed equations provide a reasonable way to predict potential benefits across the medium range of city sizes.

abstract: Thesis

abstract: Master of Engineering (ME)


title: Application of Knowledge-Based Systems and Fuzzy Logic to Automatic Control

contributor:
Sinha, N. K.
Electrical and Computer Engineering

subject:
knowledge-based systems
fuzzy logic
automatic control

abstract: This thesis investigates the application of Knowledge Based systems and Fuzzy Logic to automatic control. The knowledge used by a human operator is put in a computer usable form and applied to a control problem. The idea is not to attempt to enhance the stability or response of the system but given a basically stable and controllable system we apply human type control methods via a computer controller. A system can never be modelled exactly and therefore a controller design must allow for the uncertainty in the model. With fuzzy logic, the system inputs, outputs, parameters, reactions and cross coupling are represented in fuzzy or inexact variables, knowledge and reasoning. An exact (or nearly exact) model of the system is not necessary. A simple aircraft is the process to which this control method is applied. Knowledge, reasoning and feedback similar to what a human pilot utilizes are applied in the control of the process.

abstract: Thesis

abstract: Master of Engineering (ME)


title: Electron Bragg Reflectors for Improved Temperature Stability of InGaAsP Quantum Well Lasers

title: Electron Bragg Reflector Lasers

contributor:
Simmons, John
Engineering Physics

subject: Electron Bragg Reflectors

subject: InGaAsP quantum well lasers

subject: temperature stability

subject: temperature stability of InGaAsP quantum well lasers

subject: InGaAsP/InP Electron Bragg Reflector

subject: EBR

subject: engineering physics

subject: InGaAsP/InP

subject: InGaAsP/InP material system

subject: Electron Bragg Reflector

subject: laser

abstract: This thesis describes the incorporation within a semiconductor laser of a multiple quantum well InGaAsP/InP Electron Bragg Reflector (EBR). The EBR is intended to improve laser performance by inhibiting the escape of hot electrons from the laser active region by quantum mechanical Bragg reflection. To the author's knowledge, this investigation represents the first attempt to realize an EBR in the InGaAsP/InP material system. Computer models based on a transfer matrix method for the solution of Schrodinger's equation were written to obtain the EBR design. The transfer matrix method is described. Extensions to the transfer matrix method for optics are presented and are demonstrated to provide more than an order of magnitude improvement in computational efficiency for the calculation of the complex TE-mode propagation constant for planar graded-index waveguides with absorption or gain. The EBR designed for this work incorporates several new features. Deleterious band bending in the vicinity of the EBR is minimized by exploiting material strain to reduce the density of hole states in the EBR quantum wells. To maximize reflection bandwidth and relax fabrication tolerances, the EBR design used well widths that decreased with increasing depth into the p-type InP cladding. By the placement of the EBR adjacent to the separate confinement region, a return path was provided for electrons that scattered inelastically within the EBR. Moreover, the EBR structure was designed to support no bound electron states, so that the recombination of electrons with holes in the EBR would be minimal. To the author's knowledge, the EBR-equipped laser fabricated for this work represents the first attempt to exploit electron state exclusion. To explore the effectiveness of EBRs in the InGaAsP/InP material system, two nearly identical ridge waveguide lasers (one with an EBR, and one without) were designed, fabricated, and tested. The EBR-equipped lasers exhibited an anomalous threshold current temperature dependence which featured a "negative-To" regime (in which the threshold current decreases with increasing temperature), attaining a minimum in threshold current between T=150 K and T=200 K. These lasers had a threshold current temperature stability superior to that of standard lasers within a ~70 K window around the minimum threshold temperature. Experimental evidence suggests that the improved stability is not due to quantum mechanical Bragg reflection provided by the EBR, but is attributable to the temperature-dependent rate of hole escape from the EBR quantum wells into the separate confinement region. The proposed mechanism is described in detail and is supported by theoretical and experimental evidence. The results have implications for device design, because the mechanism by which the superior temperature stability is achieved does not rely on the electron coherence effects; the mathematical model suggests that the mechanism can be exploited to provide superior temperature stability in semiconductor lasers at 300 K or above.

abstract: Thesis

abstract: Master of Engineering (ME)


title: The Growth of East African Literature in English

title: East African Literature

contributor:
Vichert, Gordon
English

subject:
east african literature
english

abstract: Starting with a broad attempt to define the general concerns in African literature, and the cultural esthetics which form the basis of this writing, this thesis tries to place the emerging East African literature in English literature in English into the stream of African literature, and of literature at large. It focusses particularly on the works of Okot p'Bitek and James Ngugi and treats broadly the themes emerging from the East African environment and the artistic challenges which these themes pose to the writer. It concludes that meaning and strength in this emerging literature will stem from the writer's awareness and sensibility to their environment and a willingness to make an honest and artistic appraisal of this situation.

abstract: Thesis

abstract: Master of Arts (MA)


title: Analysis of a Two Server Polling System with Overlapping Skills and 1-Limited Service

contributor:
Gupta, Diwakar
Statistics

subject:
two server polling system
polling system
overlapping skills
1 limited service

abstract: The main aim of the thesis is to find the optimal division of load in the three queues, i.e. the optimal degree of overlap of skills between the two servers with waiting time in queue as the performance measure. The model under consideration is a polling system with two servers and three queues - two specialized queues, 1 and 2, and a common queue, queue 3. One of the servers cycles between queues 1 and 3 and the other between 2 and 3. The imbedded Markov chain state equations and the functional equations for queue length probability generating functions are formulated. It was not possible to obtain a closed for expression for the exact mean waiting time in the queues by solving the functional equations. So, an attempt has been made to get an approximate closed form expression that could be used to find the optimal division of load in the three queues. Since the results are available only for the symmetric system we first assume the two specialized queues to be identical. But later we relax this assumption and give approximation method for the asymmetric system. The recommended method to approximate the mean waiting time in a queue can be used to determine the optimal allocation of load to the three queues.

abstract: Thesis

abstract: Master of Science (MSc)


title: The Blind Deconvolution of Linearly Blurred Images using non-Parametric Stabilizing Functions

contributor:
Reilly, James
Electrical and Computer Engineering

subject:
blind deconvolution
linearly blurred line
non-parametric stabilizing function

abstract: An iterative solution to the problem of blind image deconvolution is presented whereby a previous image estimate is explicitly used in the new image estimation process. The previous image is pre-filtered using an adaptive, non-parametric stabilizing function that is updated based on a current error estimate. This function is experimentally shown to dramatically benefit the convergence rate for the a priori restoration case. Noise propagation from one iteration to the next is reduced by the use of a second, regularizing operator, resulting in a hybrid iteration technique. Further, error terms are developed that shed new light on the error propagation properties of this method and others by quantifying the extent of noise and regularization error propagation. Optimal non-parametric, frequency adaptive stabilizing and regularization functions are then derived based on this error analysis.

abstract: Thesis

abstract: Master of Engineering (ME)


title: Preprocessing and Postprocessing in Linear Optimization

contributor:
Terlaky, Tamas
Computing and Software

subject:
preprocessing
postprocessing
linear optimization

abstract:
This thesis gives an overall survey of preprocessing and postprocessing techniques in linear optimization (LO) and its implementations in the software package McMaster Interior Point Method (McIPM).
We first review the basic concepts and theorems in LO. Then we present all the techniques used in preprocessing and the corresponding operations in postprocessing. Further, we discuss the implementation issues in our software development. Finally we test a series of problems from the Netlib test set and compare our results with state of the art software, such as LIPSOL and CPLEX.

abstract: Thesis

abstract: Master of Science (MS)


title: Electroabsorption & Electrorefractoin in InP/InAsP & GaAs/AlGaAs Multiple Quantum Well Waveguides

contributor:
Jessop, P. E.
Engineering Physics

subject:
electroabsorption
electrorefraction
InP/InAsP
GaAs/AlGaAs
quantum well waveguide

abstract:
Electroabsorption and electrorefraction were studied in GaAs/AlGaAs and InP/InAsP multiple quantum well waveguides. Measurements of changes of the absorption coefficient and the refractive index with wavelength and bias voltage were made. Switching ratios of up to 18 dB were obtained for the GaAs/AlGaAs material. The Kramers-Kronig relation was used to calculate the theoretical phase shifts from the absorption
coefficient data.

abstract: Thesis

abstract: Master of Engineering (ME)


title: The First and Subsequent Ovarian Cycles of the House Fly, Musca domestica L., in Relation to Chemically Defined Nutritional Requirements of the Adult

title: Nutrition and OOgenesis in the Adult House Fly

contributor:
Davies, D. M.
Biology

subject:
ovarian cycle
house fly
musca domestica
nutritional requirements

abstract:
A study of the nutritional requirements of adult house flies has shown that liquid diets of natural and purified products are capable of supporting continued oogenesis. Chemically defined liquid diets containing nine 1-amino acids
fed to newly emerged female flies were necessary for ovarian maturation and oviposition. Water, salts and carbohydrate were the other basic dietary requirements for this process and for survival. The addition of cholesterol to this synthetic diet also influenced fecundity. For the maturation and oviposition of more than one ovarian cycle the synthetic diet had to be supplemented with the amino acid 1-methionine, certain B-vitamins and nucleic acid bases. Flies fed diets deficient in these supplements showed a lower fecundity and survival. A dry synthetic diet was developed which supported egg production.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: The Gamma-Ray Spectra of Iridium 192 and Iridium 194

contributor:
Johns, M. W.
Physics

subject:
gamma-ray spectra
iridium 192
iridium 194

abstract: This thesis describes an investigation of the complex gamma-ray spectra accompanying the decay of iridium 192 and iridium 194. Precision energy measurements of twenty-one gamma-rays in Ir 192 and fourteen gamma-rays in Ir 194 have been made using the 50 cm. double focusing beta-ray spectrometer. In addition, the angular correlation function for the cascade gamma-rays of Ir 194 has been determined. A number of new radiations have been found In each spectrum and decay schemes are proposed for each nuclide.

abstract: Thesis

abstract: Master of Science (MS)


title: A FORTRAN Graphics and Animation Library for X Windows

contributor:
Dumont, Randall
Griffin, Robin
Computation

subject:
FORTRAN
animation library
X Windows
FORTRAN graphics

abstract: The requirements for a computer package for the graphical animation and visualization of scientific data are discussed. It is concluded from the analysis of these requirements that simplicity of implementation, interactive response and FORTRAN compatibility are features that are strongly desired by users. These features have a major impact on the design of the graphical library. The handling of graphics resources is further complicated by the need to remove the details of resource management from the FORTRAN programmer while at the same time maintaining some degree of flexibility and efficiency. A “black box” system of graphics library primitives has been constructed to conform the needs of the FORTRAN programmer. The library primitives are constructed from a lower-level commercial graphics library to simplify resource management and give the library a FORTRAN ‘flavor’. A modular style of programming that emphasizes event-driven passing of program control is developed to guide the FORTRAN programmer. A User’s Manual containing a series of instructional tutorials as well as a routine-by-routine description of the library is included along with a code listing.

abstract: Thesis

abstract: Master of Science (MS)


title: The Effects of Peer Group Support Upon Discussion and Opinion Change in a Two-Person Group

title: Peer Group Support as a Factor in Opinion Change

contributor:
Carment, D. W.
Psychology

subject:
peer group support
discussion and opinion
two-person group

abstract:
An experiment was conducted to determine the effects of varying amounts of peer group support on discussion and opinion change in a two-person verbal interaction.
The results indicated that males speak more than females, subjects in groups where there was unequal support spoke more and made more positive and fewer neutral statements than subjects in groups with equal support. The most neutral and fewest positive statements were emitted in groups where subjects each had a moderate amount of support.

abstract: Thesis

abstract: Master of Arts (MA)


title: Growth Optimization and Fabrication of 980nm InGaAs/GaAs/InGaP Lasers

title: InGaAs/GaAs/InGaP 980nm Lasers

contributor:
Thompson, D. A.
Simmons, J. G.
Engineering Physics

subject:
growth optimization
fabrication
980nm
InGaAs
GaAs
InGaP
laser

abstract:
The growth optimization and fabrication of 980nm quantum well (QW) lasers is
presented. Photoluminescence (PL) spectroscopy is used to determine the optimized
growth conditions for the QWs. The results are presented for optimization of both
growth temperature and group V overpressure. Broad area lasers, with active regions grown at and around optimized QW growth conditions, are fabricated and characterized under pulsed conditions. These results are used to determine the optimum growth conditions for a ridge waveguide (RWG) laser structure. Once grown, RWG lasers are fabricated and characterized under continuous wave (CW) conditions. External quantum efficiencies as high as 71 % and cavity losses as low as 5.2 cm-1 are achieved.

abstract: Thesis

abstract: Master of Engineering (ME)


title: Masses of Ru98, Ru99, Os189, and Os192

contributor:
Duckworth, H. E.
Physics

subject: masses

subject: Ru98

subject: Ru99

subject: Os189

subject: Os192

abstract: Mass spectrographic masses have been determined for the nuclides Ru98, Ru99, Os189, and Os192. The Ru masses are used in a discussion of the Mo - Ru isobaric mass differences. A packing fraction curve is drawn for the heavy elements from previous mass spectrographic data combined with the Os masses. This curve is used to predict several masses of atoms of odd mass number.

abstract: Thesis

abstract: Master of Science (MS)


title: The Development of a Device-Independent Computer Graphics Library Based on the Core System

title: A Device-Independent Computer Graphics Library

contributor:
Redish, K. A.
Computation

subject:
device-independent
computer graphics library
core system

abstract: It has been recognized for some years that the use of computer graphics systems has great potential for improving man/computer communication. In the past, however, the high cost of graphics hardware, and the lack of accepted principles for graphics programming, prevented the widespread use of such systems. Recently, hardware has become more readily available, and efforts have been made to develop graphics software standards. This report presents an overview of one of the proposed standards, the Core System, and also discusses a portable subroutine library, based on the the Core System, that has been developed for use at McMaster University. This library, called SSOCS, is written in Pascal, and allows a user to produce two-dimensional images without regard to the characteristics of the graphics devices being used.

abstract: Thesis

abstract: Master of Science (MS)


title: Motivational Properties of Nonreward: A) Frustration Effect and Change of Stimulus Conditions B) Response Decrement and Change of Stimulus Conditions

title: Motivational Properties of Nonreward

contributor:
Penney, R. K.
Psychology

subject:
motivational properties
nonreward
frustration effect
stimulus condition
response decrement

abstract: This study attempted to test! 1) an alternative interpretation of Amsel frustration effect and, 2) the possibility of extending Bindra’s novelty theory. Sixty-eight children were trained to pull two successive levers. During training two groups, 100:50 and 100:100, were always rewarded at the first goal box (G1) whereas two other groups, 0:50 and 0:0, were never rewarded at G1. During testing groups 100:50 and 0:50 were given 50% reward at G1 while groups 100:100 and 0:0 were respectively always rewarded and never rewarded at G1. All subjects were always rewarded at G2 both during training anti testing. The data did not yield the typical frustration effect which rendered the alternative interpretation un-testable. The data offered supportive evidence for Bindra’s novelty theory.

abstract: Thesis

abstract: Master of Arts (MA)


title: The Effect of Shear Rate on the Inherent and Intrinsic Viscosity of Dilute Polystyrene Solutions

contributor:
Cragg, l. h.
Chemistry

subject:
shear rate
intrinsic viscosity
dilute polystyrene solution

abstract:
A study of the effect of shear rate on the inherent and intrinsic viscosities of polystyrene
fractions, in dilute solution was carried out. Inherent viscosities were determined for five
fractions (of molecular weights ranging from 2.9 x 10 to 4.8 x 106); in three solvents (Benzene, Toluene and Methyl Ethyl Ketone); at five temperatures (from 15°C to 85°C); and shear rates ranging from 1.0 x 103 to 2.8 x 104 sec.-1. Inherent viscosities thus determined were extrapolated to zero rate of shear and the extrapolated values plotted against concentration to determine intrinsic viscosities at zero rate of shear, [N] D=0 The inherent viscosity decreased with increasing shear rate. The slope of the curve of inherent viscosity vs shear rate was found to increase (ie become more negative) with increasing concentration, temperature and molecular weight and to be less in a poor solvent than in a good solvent. At very high molecular weights the value of inherent viscosity was found to decrease non-linearly with shear rate. The intrinsic viscosity was found to decrease
with increasing shear rate. The slope of the [N] vs D curve was found to increase with increasing molecular weight and decreasing temperature; the slopes were smaller the
poorer the solvent. For the three lower fractions the intrinsic viscosity was found to decrease with increasing temperature, very slightly in Methyl Ethyl Ketone and appreciably in
Benzene and Toluene, the relative being greater at higher molecular weights. With the two highest fractions this trend was reversed. The slope of the [N] D=0 vs T curve becoming less negative (and actually positive for Benzene end Toluene). The [N] vs T curves ( [N] at free fall) for the three lower fractions were parallel to those at zero rate of shears but of lower intrinsic viscosity values. With the two highest fractions, the slope of the [N] vs T curve became less negative but not to as great a degree as was found with [N] D=0 vs curves. Intrinsic viscosities obtained at zero rate of shear were applied to the Flory-Fox theory. Calculated intrinsic viscosities for polystyrene fractions in Benzene and Toluene were found to agree to within+-4% of the experimental results. For Methyl Ethyl Ketone a wide variation in values was obtained.

abstract: Thesis

abstract: Master of Science (MS)


title: Procurement and Assessment of Respiratory Values Pertinent to Early Embryonic Development of Ginkgo biloba L.

title: Respiratory Values During Embryonic Development of Ginkgo biloba L.

contributor:
Radforth, N. W.
Biology

subject:
procurement
assessment
respiratory values
early embryonic
Ginkgo biloba

abstract: An approach is developed for determining respiratory values of ovules and embryos of Ginkgo biloba L. An analysis of respiratory drift is supplemented by secondary experiments on factors influencing respiration as affecting growth.

abstract: Thesis

abstract: Master of Science (MS)


title: Flow-Induced Vibrations of a Rotary Mixing Blade

contributor:
Weaver, D. S.
Mechanical Engineering

subject:
flow-induced vibration
rotary mixing blade

abstract:
Bluff bodies immersed in a fluid stream are susceptible to flow-induced vibrations. Depending on the body dynamic characteristics and flow conditions, different types of flow-induced vibrations may occur. The failure of a blade in a large mixing vessel in a chemical plant raised the question of the response of a parabolic cross-section bluff body to the flow excitation. Experiments were conducted in a wind tunnel using two- dimensional “sectional” models. Models with parabolic, semi-elliptic and semi-circular cross-section were investigated. In the dynamic experiments, flow velocity was increased from 0 to 22 m\s, and the oscillating amplitude and wake response were monitored. Vortex-induced vibrations were observed with Strouhal numbers for parabolic and semi-circular cross-sections of 0.13 and 0.12, respectively. Steady lift force and fluid moment for different angles of attack were monitored in the static experiments. From these results, lift and moment coefficients were calculated. For the closed semi-circular cross-section, Reynolds number had a strong influence on the lift coefficient. With an increase in Reynolds number, the lift coefficient decreased. The largest difference was noted at an angle of attack a = 45°. In contrast, the open semi-circular model lift coefficient was independent of Reynolds number. In the experiments where the elastic axis of the model coincided with the model centre of gravity, galloping was not observed in the plunge mode. When the model elastic axis was moved to a position 90 mm behind the test model centre of gravity, galloping was observed for the semi-elliptic and parabolic models. The onset of galloping coincided with the vortex-induced resonance. Changing the model elastic axis position introduced a combination of plunge and torsional motion, and latter is believed to be responsible for the existence of galloping. The parabolic model was modified in an attempt to eliminate galloping instability. Fins were added at the separation points to widen the wake and prevent the reattachment of the flow to the afterbody. With these changes, galloping was not observed, although the oscillation amplitudes remained unacceptably high.
The present investigation revealed previously unknown characteristics of semi-elliptical and parabolic cross-section bluff body behaviour in fluid flow. At the same time, it laid a foundation for the solution to the practical problem encountered when a parabolic cross-section bluff body was used as a mixing blade.

abstract: Thesis

abstract: Master of Engineering (ME)