contributor:
Miller, J.J.
Biology

abstract: Title: Changes in Respiratory Capacity and the Loss of Acid-fastness During Yeast Ascospore Germination, Author: Joseph L. Seigel, Location: Thode

abstract:
Experiments are described which investigate the effect of some nutritional and environmental factors on the germination of yeast ascospores. The factors stressed are the carbon and nitrogen sources and the gaseous environment. Loss of acid-fastness and changes in respiratory activity are investigated for their suitability as germination criteria.

In the discussion, the respiratory features of the three major phases in the life cycle of yeast, that is, growth, sporulation, and germination, are compared.

abstract: Thesis

abstract: Master of Science (MS)


title: Reaction Accompanied Mass Transfer Between Liquid Phases - An Experimental Study

contributor:
Johnson, A. I.
Hamielec, A. E.
Chemical Engineering

subject: reaction, mass transfer, liquid phases

abstract:
 This dissertation describes an experimental study of the simultaneous mass transfer and chemical reaction at a plane liquid-liquid interface involving the saponification of simple esters transferring into aqueous caustic solutions. The transfer experiments were carried out with both liquid phases stirred and unstirred respectively.

 Special emphasis was placed on the stagnant-phase systems. Turbulent reaction layer propagation rates were measured for ester phases (pre-saturated with water) in contact wiith aqueous caustic solutions (at various concentration levels). The distortion of the moire pattern was used to indicate the position of the propagating layer front. The cause and nature of the turbulent layer were elucidated. An
apparatus, capable of withdrawing small samples of the liquid with probes precisely located in the aqueous phase, was constructed. Experimental techniques were developed to measure the abnormal concentration profiles of the reactants and the products within the turbulent layer. From the component concentration distribution data, the turbulent layer thicknesses, the reaction zone (within the turbulent layer) thicknesses, the mass transfer rates, and the enhancement factors were deduced. The effects of turbulence in the aqueous phase were
estimated in terms of the derived eddy diffusivities and of the differences between the experimentally measured and the theoretically predicted (by molecular diffusion with reaction
equation) enhancement factors.

 In the steady state transfer study using stirring in
both phases, transfer rate data and enhancement factor data were obtained for three formate-sodium hydroxide systems.

 In addition to the mass transfer studies, a preliminary
investigation on the diffusion coefficient measurement in binary and ternary liquid systems employing the moire pattern method was carried out. A diffusion cell was designed and built to enable the quick acquisition of the experimental data with reasonable accuracy.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Thermal Management and Solidification Characteristics in High Performance Aluminum Casting

contributor:
McDermid, Joseph
Kish, Joseph
Shankar, Sumanth
Mechanical Engineering

subject:
mold thickness
solidification front

abstract:
Weight reduction in automobiles is amongst the most economical ways of reducing greenhouse gas emissions and increasing fuel efficiency. The recently invented ablation casting process is a novel technique of producing high performance light weight parts which meet this objective. In this technique a water jet demolds the water soluble sand mold and subsequently impinges upon the solidifying metal, thereby producing high cooling rates in the casting which in turn leads to microstructural refinement and higher mechanical properties.
The objective of this study was to develop a comprehensive understanding of the effect of various parameters involved in the casting of a thin walled part using the HiPerMag casting process for the wrought aluminum alloy AA 7050.
The study is divided into three major parts that deal with the composition of the sand binder system, optimization of the sand mold thickness, various aspects of the water jet parameters and the desired microstructural parameters which will result in a defect free part.
In first phase of the study, sand mold properties such as the green and dry strengths of the water soluble sand binder system used in the study were tested to ensure that they meet the molding requirements. An average green strength of 160 kPa and an average dry strength of 3825 kPa were found for the water soluble sand binder system. These values were similar to those reported in the literature for clay bonded sands and were sufficient to make molds for casting in the current study.
Secondly, a heat transfer model was developed to find a minimum mold thickness required to design a mold for the HiPerMag casting process such that the liquid metal remained sufficiently insulated before being quenched. Based on the model, for a mold with a cope thickness of 12.9 cm, the heat flux losses to the surroundings were reduced by up to 90 % versus a case where a thinner mold was used.
In addition, an analytical solution was derived for the mold thickness problem from which it was found that at a distance of 10 cm from the mold cavity there was a negligible increase in temperature of the sand at that location at large times.
Further, the minimum mold thickness was determined based on the temperature profile in the sand mold during the HiPerMag casting process. This study showed that a thin mold of about 2 cm thickness was sufficient to provide insulation to the hot metal during the HiPerMag casting process.
Thirdly, it was found that, based on cooling curve data and microstructural analysis, that a jet spacing of 15.3 cm and a time delay of 7.4 s between successive jet activations starting from the farthest jet (located near the edge of the casting), was necessary to obtain a single solidification front throughout the casting. This also ensured that grain size variation in the casting was less than 10 μm for having uniform mechanical properties.
Also, it was found for a thin walled casting, the amount of solid present in the solidifying casting at the time of water jet impingement had a negligible effect on the movement of the solidification interface.
Finally, the effect of jet momentum on surface defects was examined. It was determined that the maximum jet momentum resulting in no surface defects at temperatures close to the liquidus for Al AA 6061 alloy was approximately 2 kg.m/s.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Characterizing the interactions of ATP and DNA with the MutL Mismatch Repair protein

contributor:
Guarné, Alba
Biochemistry and Biomedical Sciences

subject: MutL, mismatch repair, ATP, DNA, endonuclease activity

abstract: The fidelity of DNA replication prevents mutations that may lead to cancer predisposition or neurodegenerative diseases. One mechanism that enhances DNA replication fidelity is DNA mismatch repair, which corrects mismatches and small insertion/deletion loops that have escaped polymerase proofreading. In all eukaryotes and most prokaryotes, MutL (a key mismatch repair protein) has an intrinsic endonuclease activity that nicks the newly synthesized strand and recruits downstream factors to remove and correct errors. It has been proposed that ATP binding promotes a series of conformational changes that induce structural order within MutL and stimulates its endonuclease activity. The C-terminal domain of MutL, which harbors the endonuclease site, does not bind to DNA. This has prevented the molecular characterization of its endonuclease activity. In this thesis, we first show that MutL in B. subtilis exhibits asymmetric conformations similar to yeast and human MutL homologs. We also devise a novel approach to bypass the binding defect of the C-terminal domain by using fusion proteins. We find that these fusions bind to DNA specifically and, in the presence of the processivity clamp, can nick DNA. One of these fusion proteins in particular stimulates the nicking activity much more efficiently than the C-terminal domain alone. This work lays the foundation for the mechanistic characterization of the MutL endonuclease and provides a method to stabilize transient protein-DNA interactions.

abstract: Thesis

abstract: Master of Science (MSc)


title: MODELING, ESTIMATION AND BENCHMARKING OF LITHIUM ION ELECTRIC BICYCLE BATTERY

contributor:
Emadi, Ali
Malysz, Pawel
Electrical and Computer Engineering

subject:
Electrical Bicycle
Battery Management System
Battery Parameterization
Optimization Algorithm
Quadratic Programming
E-bicycle Benchmarking

abstract:
As a conventional transportation modality, bicycles have been gradually electrified to meet the desire for convenient and green commuting patterns, especially in developed urban areas. The electric bicycle battery pack and its management system are core elements that determine key performance metrics such as electric range and output power. With respect to electric bicycle applications, focused research on the battery, its management system, and performance has received less attention compared to other energy storage applications.
In this thesis, a well-developed conversion kit produced by BionX is studied. A data collecting system is first installed to record both mechanical and electrical data, such as speed, power and voltage; this enables defining two standard riding cycles at different riding conditions. Two benchmarking tests are performed to investigate the battery life in pure electric mode and at different threshold levels of optimal assistance.
A novel quadratic programming based fitting algorithm is derived and applied in both time and frequency domain parameter identification tests. The proposed algorithm is able to fit single/multiple pulses by applying a masking vector. Sensitivity study and experimental results show the high robustness and fast computation time of the approach compared to existing and commonly used methods, such as fmincon. The comparison between hybrid power pulse characterization (HPPC) and electrochemical impedance spectrum (EIS) tests are performed in terms of extracted internal resistance.
A second-order RC battery model is developed using parameters extracted from HPPC tests. The model is validated by experimental riding cycles and used to generate the reference SOC profiles that are employed in a SOC estimation study. Four estimation strategies, including extended Kalman Filter (EKF), Sigma point Kalman Filter (SPKF), Cubature Kalman Filter (CKF), and joint extended Kalman Filter (JEKF), are compared systematically in terms of accuracy, robustness and computation complexity.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: A QUASI-LIKELIHOOD METHOD TO DETECT DIFFERENTIALLY EXPRESSED GENES IN RNA-SEQUENCE DATA

contributor: Clinical Epidemiology/Clinical Epidemiology & Biostatistics

subject: RNA-seq Quasi-likelihood RPKM

abstract:
In recent years, the RNA-sequencing (RNA-seq) method, which measures the transcriptome by counting short sequencing reads obtained by high-throughput sequencing, is replacing the microarray technology as the major platform in gene expression studies. The large amount of discrete data in RNA-seq experiments calls for effective analysis methods. In this dissertation, a new method to detect differentially expressed genes based on quasi-likelihood theory is developed in experiments with a completely randomized design with two experimental conditions. The proposed method estimates the variance function empirically and consequently it has similar sensitivities and FDRs across distributions with different variance functions. In a simulation study, the method is shown to have similar sensitivities and FDRs across the data with three different types of variance functions compared with some other popular methods. This method is applied to a real dataset with two experimental conditions along with some competing methods.
The new method is then extended to more complex designs such as an experiment with multiple experimental conditions, an experiment with block design and an experiment with factorial design. The same advantages for the new method have been found in simulation studies. This method and some competing methods are applied to three real datasets with complex designs.
The new method is also applied to analyze reads per kilobase per million mapped reads (RPKM) data. In the simulation, the method is compared with the Linear Models for Microarray Data (LIMMA) originally developed for microarray analysis (Smyth, 2004) and the question of normalization is also examined. It is shown that the new method and the LIMMA method have similar performance. Further normalization is required for the proper analysis of the RPKM data and the best such normalization is the scaling method. Analyzing raw count data properly has better performance than analyzing the RPKM data. Different normalization and statistical methods are applied to a real dataset with varied gene length across samples.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Digital Walsh-Fourier Analyser for Periodic Waveforms

contributor:
Kitai, R.
Electrical Engineering

subject: digital, walsh-fourier, periodic, waveforms, frequency, circuits

abstract: This thesis describes a proposed design of a special-purpose digital instrument that will obtain the first 32 coefficients of the Walsh-Fourier series of a low-fundamental frequency periodic voltage. The mathematics are developed for applying Walsh functions to obtain a Walsh-Fourier series in the same manner as sinusoidal waves are used to obtain a Fourier series of a periodic wave. It is shown how Walsh-Fourier coefficients are employed to obtain a Fourier series. Some familiar waveforms are shown as examples. The mathematical concepts are applied to the design of the instrument, of which two major portions have been constructed using integrated circuits. The Walsh-Fourier coefficients are available at the end of the second cycle of the input. The upper fundamental frequency limit of the instrument is approximately 60 Hz. There is no low-frequency limit.

abstract: Thesis

abstract: Master of Engineering (MEngr)


title: Hamyrolysis of Illite and Montmorillonite: An Experimental Investigation

contributor:
Kramer, J. R.
Geology

subject: hamyrolysis, illite, montmorillonite, mineralogical, cations

abstract:
 The short term (5000 hours) stability of illite and montmorillonite in sea water was studied by suspending 5.00 gm. aliquots of A.P.I. reference clays Montmorillonite # 25b and Illite # 35 in 500 ml. of artificial sea water (tradename "Instant Ocean") . After 5000 hours, in the montmorillonite samples, Ca and Si concentrations had increased (0.490 mmoles/l and 0.289 mmoles/l respectively), the cation exchange capacity had decreased (104.36 meq/100 gms. to 81.42 meq/100 gms.), the pH had decreased (8.40 to 7.94) but no major mineralogical change was observed. After 5000 hours, in the illite samples, Si concentration had increased (0.045 mmoles/l), the cation exchange capacity remained the same, the pH increased (7.22 to 7.60) and no major mineralogical change was observed. The release of Ca in the illite samples was complicated by the dissolution of calcite and significant changes in concentration of other cations (Na, K, Mg) were not observed.

 The data for Si, cation exchange and exchangeable cations are compared to that of Lewis (1950), Whitehouse and McCarter (1956), Carrol and Starkey (1958), MacKenzie et al (1965) (1967) and Russell (1970), a model developed by Houston (1972) is used to explain the Ca and Si data for the montmorillonite samples, and the implications of the apparent stability of these minerals to the case for authigenic clay formation from detrital material are discussed.

abstract: Thesis

abstract: Bachelor of Science (BSc)


title: An Experimental Study of the Effects of Aqueous Polymer Solutions on a Liquid Boundary Layer

contributor:
Latto, B.
Mechanical Engineering

subject: aqueous, polymer, solutions, liquid, boundary layer, dilute

abstract:
 This thesis is an experimental study of the effects of injecting dilute polymer solutions into a turbulent boundary layer developed on a flat plate submerged in water.

 A flat plate having a plexiglass surface together with a separate leading edge piece were specially designed for observing the boundary layer phenomena. Aqueous polymer solutions were
introduced into the boundary layer through a slit situated in the leading edge piece. Hot-film anemometer technique was employed in the measurements of velocity profiles, turbulence intensities and lateral correlation coefficients at several locations on the plate. The investigation was carried out for two Reynolds Numbers, based on the length of the plate, of 2.4 x 10^5 and 6.4 x 10^5. The variation in the drag force with respect to the polymer concentrations and the injection rates was assessed based on the velocity profile data. It was found that the momentum diffusivity was smaller than for pure water, and that the presence of the polymer molecules seemed to promote a more uniform distribution of the sizes of the turbulence eddies.

abstract: Thesis

abstract: Master of Engineering (MEngr)


title: The Effect of Frequency, Doping and Temperature on the Complex Permittivity of N-Type Germanium

contributor:
Gunn, M. W.
Electrical Engineering

subject: frequency, doping, temperature, complex permittivity, n-type, germanium, conductivity, semiconductor

abstract:
 A number of microwave measuring techniques for the measurement of the complex permittivity (^ɛ = ɛo ɛr - j σ/ω) have been investigated and a new method based on the replacement of the narrow wall of a rectangular wave-guide by a block of semi-conductor has been developed. This technique is shown to be suitable for the measurement of σ when
σ >> ωɛo ɛr and for the measurement of σ and ɛr for σ ≃ ωɛo ɛr.

 An investigation has been made of the propagation characteristics of a rectangular wave-guide containing a centrally placed slab of semi-conductor parallel to the narrow walls of the guide. A comparison of exact solutions for the propagation constant in such a structure with the approximate solutions normally used has shown that the conditions for the validity of the approximate solutions are much more stringent than has been reported previously. It is further shown that under certain conditions the structure offers a convenient method of measuring the conductivity of a semi-conductor. In addition, a theoretical and experimental investigation of the effects of the higher order modes excited at the interface of such a structure with an empty wave-guide has been made. The study has shown that under certain conditions, the effects of these modes can be significant.

 A theoretical and experimental study has also been made of the effects of temperature, frequency and doping on the complex permittivity of lightly doped n-type germanium. Measurements of these effects which have not been reported previously have been made over a temperature range 100°K - 500°K at frequencies 9.25 and 34.5 GHz and confirm the theoretical model used.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


abstract: Title: Mass Transfer Across a Liquid-Liquid Interface with and Without Chemical Reaction, Author: P. Seto, Location: Thode

abstract:
The present study is divided into two parts. Part I was an attempt to investigate the steady state mass transfer across a liquid-liquid interface accompanied by a very slow, second order, irreversible chemical reaction using a glass vessel. Both liquid phases were well stirred and the lower phase was allowed to flow in and out of the reactor continuously. The system chosen for the study was ethyl acetate-sodium hydroxide solution. In order to simplify the transfer situation, the ethyl acetate phase was pre-situated with water, so that the transfer became uni-directional, from the upper phase into the lower phase. Experimental runs were performed at 25°C, 40°C and 55°C temperature levels and at various sodium hydroxide concentrations ranging from 0.0002 N. up to 0.389 N. (while other experimental conditions, for example, stirrer speeds and lower phase flowrates were kept constant). In each run, transfer rate of ethyl acetate into the lower phase was measured and the mass transfer coefficient was calculated.

The results showed (a) Van Krevelen's film model for slow, second order, irreversible reaction system did not apply to ethyl acetate-sodium hydroxide because the reaction involved was too slow to cause any enhancement in mass transfer. (b) Mass trnasfer coefficient for reaction run was smaller than that for physical transfer into water; and the different was accounted for by an interfacial resistance (l/kr) apart from salt effect of sodium hydroxide and sodium acetate.

The resistance (1/kr) varied directly as the concentration of sodium acetate, which, in turn, varied as a positive function of input sodium hydroxide concentrations in the bulk lower phase.

The cause of the retardation to transfer was still uncertain. However, it was speculated to be due to (a) Modification of hydrodynamic conditions near the interface by salt and reaction effect. (b) Formation of a surface barrier due to the presence of impurities. (c) Formation of an additional reaction zone or film due to a very slow chemical reaction.

In addition, an analogue study on concentration profiles of reactants and products in a film model was carried out. Also, J. B. Lewis' experiments were partly repeated and his method of evaluating physical mass transfer coefficients was discussed.

Part II was a study of unsteady state diffusion accompanied by
a slow, second order, irreversible chemical reaction across unstirred
liquid-liquid phases. The systems of ethyl formate-sodium hydroxide and
ethyl acetate-sodium hydroxide were chosen.

The results of the schlieren investigation showed that when the ethyl ester, pre-saturated with water, was in contact with the sodium hydroxide phase, a zone was formed inside which reaction occurred. Turbulent liquid motion was observed in the zone which extended itself in course of time during the experiment.

A great part of the experimental work was spent in an effort to search for information about the zone. The Moire pattern was made use of in studying the zone propagation. Experiments were performed at room temperature, with each of the ethyl ester contacting sodium hydroxide solution at various concentrations (one concentration for each experiment).

The reaction zone thus formed was photographed at intervals. About 25 photographs were taken for each run. They were developed and analysed. In some runs, concentrations of reactants inside the zone were measured.

The results showed (a) The speed of zone propagation was higher in the ethyl formate-sodium hydroxide system than in the ethyl acetate-sodium hydroxide system. Within the system the speed increased with initial sodium hydroxide concentration used, then passed through a maximum, and decreased with increasing sodium hydroxide concentration. (b) Concentrations of both reactants inside the zone were low as compared to their initial concentrations.

A simple model was proposed to describe the zone propagation making use of the concept of eddy diffusivities.

abstract: Thesis

abstract: Master of Engineering (ME)


title: The Influence of Interfaces on Dislocation Mobility

contributor:
Embury, J. D.
Metallurgy and Materials Science

subject: interfaces, dislocation, mobility, stress field

abstract:
 A numerical method was developed to calculate the passing stress of pile-ups in a general internal stress field. This method was used to calculate the passing stress for a pile-up of like edge dislocations for a sinusoidal internal stress field, a simple tilt wall, and a
Van der Merwe net of misfit dislocations. The passing stresses for single dislocation for these internal stress fields were also calculated.

 The Burgers vectors of a common set of misfit dislocations at the interface of Ni3Ge particles in a Ni matrix were determined. The
surface slip lines of a directionally solidified sample of Ni-20% Ge alloy tested in compression were examined.

abstract: Thesis

abstract: Master of Engineering (MEngr)


title: Carbon and Oxygen Isotope Studies in Marbles

contributor:
Schwarcz, H. P.
Geochemistry

subject: carbon, oxygen, isotope, marbles, temperature, reactions

abstract:
 Fractionations of C^13/C^12, O^18/O^16 ratios and Mg between coexisting dolomite and calcite have been determined from rocks of a variety of metamorphic grades in Vermont and the Grenville of Ontario. Working criteria for equilibrium are established. Temperature dependent fractionation expressions are derived (1) for O^18 and C^13 from the C-and
O-isotope fractionations concordant with the Mg-calcite solvus thermometer, for T = 130° to 550°C, using natural dolomite-calcite assemblages; (2) for C^13 from hydrothermal partial exchange experiments. Problems with partial exchange reactions are discussed. A thermodynamic analysis of the solvus relations shows that spinodal decomposition probably is
important in high Mg-calcites. Quench phenomena in high grade assemblages are complex. The quench temperature may be much lower than the maximum temperature attained. The sizes of some equilibrium systems are delineated.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Conversion Methods for Improving Structural Analysis of Differential-Algebraic Equation Systems

contributor:
Nedialkov, Ned
Computational Engineering and Science

subject:
Differential-algebraic equations
Structural analysis
Computer algebra
Block triangular form
Modeling and simulation

abstract:
Systems of differential-algebraic equations (DAEs) arise in many areas including chemical engineering, electrical circuit simulation, and robotics. Such systems are routinely generated by simulation and modeling environments, like MapleSim, Matlab/Simulink, and those based on the Modelica language. Before a simulation starts and a numerical solution method is applied, some kind of structural analysis (SA) is performed to determine the structure and the index of a DAE system.
Structural analysis methods serve as a necessary preprocessing stage, and among them, Pantelides's graph-theory-based algorithm is widely used in industry. Recently, Pryce's Σ-method is becoming increasingly popular, owing to its straightforward approach and capability of analyzing high-order systems. Both methods are equivalent in the sense that (a) when one succeeds, producing a nonsingular Jacobian, the other also succeeds, and that (b) the two give the same structural index in the case of either success or failure. When SA succeeds, the structural results can be used to perform an index reduction process, or to devise a stage-by-stage solution scheme for computing derivatives or Taylor coefficients up to some order.
Although such a success occurs on fairly many problems of interest, SA can fail on some simple, solvable DAEs with an identically singular Jacobian, and give incorrect structural information that usually includes the index. In this thesis, we focus on the Σ-method and investigate its failures. Aiming at making this SA more reliable, we develop two conversion methods for fixing SA failures. These methods reformulate a DAE on which the Σ-method fails into an equivalent problem on which SA is more likely to succeed with a nonsingular Jacobian. The implementation of our methods requires symbolic computations.
We also combine our conversion methods with block triangularization of a DAE. Using a block triangular form of a Jacobian sparsity pattern, we identify which diagonal block(s) of the Jacobian is identically singular, and then perform a conversion on each singular block. This approach can reduce the computational cost and improve the efficiency of finding a suitable conversion for fixing SA's failures.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Conformal Differential Geometry

contributor:
Lane, N. D.
Mathematics

subject: conformal, differential, geometry

abstract:
This thesis is a study of some properties of arcs which remain invariant under certain types of conformal representations. The study is carried on first in the conformal plane, then in conformal 3-space, and finally in conformal n-space. It is comprised of most of the
research on this subject which has been carried on to date by Professors N.D. Lane and Peter Scherk. I have assisted Dr. Lane in the creation of some of the material which this thesis contains.

abstract: Thesis

abstract: Master of Arts (MA)


contributor:
James, W.
Civil Engineering

abstract: Title: A Kinematic Model for Urban Drainage Study, Author: Zvi Shtifter, Location: Thode

abstract:
This study describes the development and use of a numerical storm model as a pre-processor for a detailed urban runoff model. The storm model simulates the spacial and temporal growth and decay of a system of storm cells as they move across an urban catchment system by generating hyetographs for each subcatchment.

Traditionally, design storms are developed from statistical analysis of point rainfall records that include all types of rainstorms. This methodology was considered appropriate for flood predictions based on the so-called rational formula. However, rain distributions resulting from point rainfall analysis are unlike any types of observed rainstorm. This synthetic temporal distribution is typically applied uniformly across the catchment and hydrographs are consequently unlike observed hydrographs.

The storm model presented in this study is based on synoptic observations of rain cells reported in whether radar literature. Statistics of the size and distribution of rain cells can be obtained from reported weather radar studies. Large static or slow-moving cells of uniform rainfall intensity are rare even in prolonged frontal events. Convective cells tend to be circular with a circular rainfall intensity pattern. Rain cells in frontal precipitations events tend to be elliptical, aligned sub-parallel to the front and moving sub-parallel to it. Rainfall is typically most intense near the leading edge of the cell. Fast moving storms produce very rapid point-intensity-duration changes.

A model with these features is developed. The model is applied to urban catchments of the City of Hamilton in Southern Ontario. The sensitivity of the time-to-peak and rate of rise of hydrographs and pollutographs indicate that storm cell kinematics are significant in peak runoff estimates and water pollutant loading estimates.

abstract: Thesis

abstract: Master of Engineering (ME)


contributor:
Ward, R.G.
Metallurgy

abstract: Title: Thermodynamic Properties of Liquid Iron-Chromium-Oxygen Alloys, Author: Stanely Y. Shiraishi, Location: Thode

abstract:
In this thesis the equilibrium between H2/H2O gas mixtures and iron-chromium melts was measured over a wide range of temperatures, 1470 - 1750°C. Specimens were levitated in selected H2/H2O gas mixtures, quenched and analyzed for oxygen. The gas composition fixed the oxygen potential in the system and allowed the thermodynamics of the oxygen solution reaction to be determined.

Wagner interaction parameters were employed to describe the degree of chemical interaction between chromium and oxygen.

abstract: Thesis

abstract: Master of Science (MS)


contributor:
Elliott, A.R.
Electrical Engineering

abstract: Title: Fast Transformations with Walsh-Hadamard Functions, Author: Frank Y.Y. Shum, Location: Thode

abstract: In this thesis, various techniques to generate Walsh-Hadamard functions are discussed. Efficient algorithms to compute the discrete Walsh-Hadamard transform have been derived and implemented. The design of a simple, but very fast, digital circuit that can perform the transform or its inverse is presented. These algorithms have been applied to the processing of speech for the investigation of bit rate reduction. Intelligible speech has been reconstructed from 8 or 4 dominant Walsh-Hadamard coefficients out of a field of 64, with a constant update time of 8 milliseconds, on a CDC-1700 computer.

abstract: Thesis

abstract: Master of Engineering (ME)


title: An Intelligent Cell-Level Battery/Ultracapacitor Hybrid

contributor:
Habibi, Saeid
Mechanical Engineering

abstract:
In the strive to use electric energy as the sole source of traction force in the automotive industry, the electric storage unit poses serious challenges. Although Li-Ion batteries have shown promising features, there is still room to improve the shortcomings of the electric storage unit. The chemical process of energy extraction and storage in the batteries results in inherently limited power density and lifetime. The notion of pairing a Li-Ion battery cell with an ultracapacitor will invigorate power capability of the hybrid cell. Furthermore, enabling local processing capability in each hybrid cell makes it possible to run sophisticated control and power management algorithms that result in increased battery longevity. Also, hybridization at cell level provides greater access to each cell’s momentary states which results in more accurate analysis, improved safety, and a broad control possibility.
In this research, a Li-Ion battery cell is combined with an ultracapacitor. An appropriate configuration is selected for this particular application after reviewing several hybridization schemes and converter structures. A comprehensive power management unit is designed and implemented that is able to execute several strategies to mitigate battery stresses while improving power capabilities. A current regulator is also designed and implemented to realize the proposed strategies by providing the power converter with proper duty cycle. Rather than simulation under a wide range of test loads, a prototype hybrid cell is built and tested in an experimental setup.

abstract: Thesis

abstract: Master of Applied Science (MASc)


contributor:
Embury, J.D.
Metallurgy and Materials Science

abstract: Title: Low Amplitude Fatigue Hardening of Copper Single Crystals, Author: Douglas M. Shinozaki, Location: Thode

abstract:
The detailed dislocation microstructure was determined as a
function of low amplitude fatigue in the hardening regime. Copper
single crystals were cycled in uniaxial, symmetric push-pull at room
temperature.

The dislocation microstructures were observed by thin film
electron microscopy for various extents of hardening. An attempt was
made to correlate surface slip line observations to the dislocation .
microstructures. On the basis of a similarity to the dislocation distributions
observed in stage two of uni-directional work hardening, a
model for fatigue hardening was proposed. Hirsch's stress relief theory
of stage two work hardening was used to account for the observed
dislocation distributions.

abstract: Thesis

abstract: Master of Science (MS)


title: Investigating the Role of the Extracellular Environment in Oct4-Mediated Cellular Reprogramming

title: Oct4 and Environmental Synergism in Cellular Reprogramming

contributor:
Bhatia, Mick
Biochemistry and Biomedical Sciences

abstract: M.Sc Thesis

abstract: The overexpression of one transcription factor alone – Oct4 – can alter cell fate.  In conjunction with lineage-specifying culture conditions, Oct4 can generate multi-lineage blood and neural progenitors without traversing pluripotency.  During this conversion, cells achieve a unique cellular status, distinct from that of the somatic or pluripotent states, termed Oct4-induced plasticity, or OiP.  This plastic state is characterized by a morphological shift from spindle-elongated to compact-cuboidal cells, which manifests only with culturing in Reprogramming media, suggesting that the extracellular environment plays an key role in this process.  However, the precise component(s) of the growth media that inhibit or permit sustained Oct4-expression remains unknown.  In direct support of this notion, we revealed that the serum component of Fibroblast media is a crucial factor in preventing OiP, as only serum-free formulations are able to sustain Oct4 expression and induce the plastic state.  These results uncover the importance of the extracellular environment, which works collectively with Oct4 to induce OiP, a synergism previously overlooked in the reprogramming field.  Identification of these factor(s) may allow for optimization of media formulations as well as the identification of small-molecules that may improve OiP generation or even substitute for the role of ectopic Oct4.  As well, the identification of N-cad as a marker of plastic cells as well as the generation of a screening platform to identify chemical activators of endogenous Oct4 will aid in further understanding the nature of OiP as well as the generation of transgene-free cell products.  Taken together, elucidation of the larger role of Oct4 in OiP and pluripotency will enable greater control of cell fate conversion, which is essential for this field to evolve.

abstract: Thesis

abstract: Master of Science (MSc)


title: A Systematic Scaling Solution Search in Six-Dimensional Inflation

title: A Systematic Six-Dimensional Scaling Solution Search

contributor:
Burgess, Cliff
Physics and Astronomy

subject:
cosmology
particle physics
inflation

abstract:
We explore the mechanics of inflation within simplified extra-dimensional models
involving an inflaton interacting with a Einstein-Maxwell system in two extra
dimensions. The models are complicated enough to include a stabilization
mechanism for the extra-dimensional radius, but simple enough to solve the full
six-dimensional field equations. After performing a consistent truncation, which
guarantees our six-dimensional equations are equivalently satisfied by the four dimensional
equations of motion, we explore (numerically and analytically) the
power-law solutions evident in our initial parameter search. After a comprehensive
search for potential power-law scaling solutions in both six and four dimensions,
we find two that give rise to interesting inflationary dynamics. They both
can generically exist outside of the usual four dimensional effective theory, and
yet, we still trust them since our truncation is consistent. One of these is a dynamical
attractor whose features are relatively insensitive to initial conditions, but
whose slow-roll parameters cannot be arbitrarily small; the other is not an attractor
but can roll much more slowly, until eventually transitioning to another solution
due to its unstable nature. We present a numerical and analytic discussion of these
two solutions. Four of the appendices contain calculations in more explicit detail
than are performed in the main text, while a fifth contains a representative Mathematica
worksheet and the sixth contains the general results of the systematic sweep
for scaling solutions.

abstract: Thesis

abstract: Master of Science (MSc)

abstract:
When looking out at the night sky, we see a universe that is extremely flat and
looks the same no matter what direction we stare. However, these present-day observations
require the universe to have begun under very specific circumstances,
which is not something that naturally occurs; think about what is necessary to hit a
hole-in-one with a golf club: a very precise and specific shot is required. The theory
of Cosmological Inflation—a period of rapid expansion in the early universe—is
the current leading theory proposed to explain these observations. In our exploration,
we aim to study inflation from a higher-dimensional perspective in which
two extra spatial dimensions are added to our usual three. Ultimately, we find
three classes of solutions, two of which exist outside of the regimes usually studied,
that have the potential both to explain current observations, and also be useful
tools in future explorations.


title: Measurement of the Loss in Optical Fibres

contributor:
Garside, B. K.
Engineering Physics

subject: measurement, loss, optical fibres, ionizing radiation, signal

abstract: This is Part A.

abstract:
 The equipment necessary to measure the loss in an optical fibre has been constructed. The details of the design and the results of testing the equipment are given. This equipment was designed to measure the loss induced in fibres by ionizing radiation, but can also be used to measure undamaged samples. A "dual-beam" system is used to increase the accuracy of the equipment.

 The equipment will measure the spectral attenuation of an optical fibre to an accuracy of ±1 dB/km between .9 and 1.65 μm if the fibre is at least 175m long and has an attenuation of less than 115 dB/km. Simple modifications to the equipment would reduce the sample length required for ±1 dB/km accuracy to 60 m.

 The minimum sample length is determined by the accuracy with which samples can be connected into the system. The maximum sample attenuation is determined by the signal to noise ratio. Methods of increasing the signal to noise ratio and the sample connection accuracy are discussed. Calculations based on the suggested improvements show that the sample length can be reduced to 45 m and the maximum attenuation increased to 750 dB/km for ±1 dB/km accuracy. The use of a testing method which does not require removal of the sample could give ±1 dB/km accuracy for 10 m samples.

 The operating and adjustment procedures for the equipment are given in the appendices to this report.

abstract: Thesis

abstract: Master of Engineering (MEngr)


contributor:
Hale, C.J.
Geology

abstract: Title: Seismic Velocities of the Whitestone Anorthosite and its Mylonitized Equivalents in the Parry Sound Shear Zone, Author: Arun Sen, Location: Thode

abstract:
Compressional wave velocities of the Whitestone anorthosite and its mylonitic equivalent in the Parry Sound shear zone have been measured in the field and to two kilobars in a laboratory confining pressure vessel. Mylonitiztion of the anorthosite has resulted in a preferred orientation of constituent minerals and retrograde mineral assemblages. A seimic anisotropy is consequently developed in the  mylonite such that the P-wave velocitites are lower for propagation directions perpendicular to mylonite than for its anorthosite protolith.

In the field, rock weathering and surface fractures control velocity variations.

At low confining pressure (shallow depth) the P-wave velocity anisotropy is controlled by fracturing which is in turn related to the mylonitic fabric. At approximately one kilobar pressure (depths close to five kilometres) where fractures and porosity are insignificant, the P-wave anisotropy is due solely to the aggregate mineral velocities and their solution and their orientations. The undeformed Whitestone anorthosite has an average  P-wave velocity of 7.02 km/s measured in three perpendicular directions at 2 kilobars confining pressure. The mylonite has the following P-wave velocities at 2 kilobars confining pressure: 6.83 km/s parallel to both foliation and lineation, 6.70 km/s parallel to foliation and perpendicular to lineation, and 6.57 km/s perpendicular to foliation.

abstract: Thesis

abstract: Bachelor of Science (BSc)


title: A Study of the Thermal Decomposition of Esters of Oxalic Acid

contributor:
Warkentin, J.
Chemistry

subject: thermal decomposition, Esters, oxalic acid, synthesized

abstract: This work was initiated with a view to elucidating the hitherto little-studied thermolysis of esters of oxalic acid. A number of symmetrical diesters were synthesized and several were investigated thoroughly by use of product studies, kinetic methods and kinetic isotope-effect measurements. Both preparative and pyrolytic procedures and results are recorded. The literature regarding previous studies of the effect of heat on oxalate esters is surveyed, and a review of the principles and uses of the investigative methods employed is presented. The results are discussed in the light of more recent work and both general and specific mechanisms for oxalate thermolysis are suggested.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Fractional Slot Concentrated Winding Interior Permanent Magnet Machines with Reluctance Torque: Inductance-Based Methodology for Comprehensive Analysis, Design, and Control

contributor:
Emadi, Ali
Electrical and Computer Engineering

abstract:
This thesis studies the inductance based methodology for analysis, design and control of fractional slot concentrated winding (FSCW) interior permanent magnet (IPM) machines.
The properties of FSCW are studied analytically based on the modified winding function method, which is developed based on turns function. The modified winding function method simplifies the inductance analysis of FSCW. The closed form representations of air gap inductance and mutual inductance are obtained. The inductance properties of FSCW machines with salient rotors are investigated by exploring the flux line distributions, and the equivalent air gap lengths of d- and q-axis are approximated. The inductance difference between d- and q-axis of the FSCW machine is obtained analytically and compared with the integer slot distributed winding (ISDW) machines.
An FSCW IPM machine design methodology is proposed. The relationship between the mechanical output characteristic and parameters is established, which guides the machine topology selection. The machine geometry model is developed parametrically and optimized using the response surface method (RSM), which enables the optimization to be implemented with reduced computational effort. The performances of the designed FSCW IPM machine are evaluated by comparing with the traditional designs, and it shows advantages in terms of torque capability and/or losses.
The comprehensive mathematical model of the FSCW permanent magnet synchronous machine (PMSM) is obtained, which is different from idealized PMSM model and features extra coupling terms. However, for symmetric 3-phase machines, if the windings are Y connected, the coupling terms only introduces 3rd order harmonic to 0-axis, and the field oriented control (FOC) can still be applied. The optimal current control strategies are proposed based on nonlinear optimization algorithm. The global loss minimization and the current minimization are developed and validated by finite element analysis (FEA) and/or experiments.
The FSCW IPM machine is prototyped and tested. A simplified characterization method is developed based on the machine drive. It utilizes the voltage and current variables in the control loop to identify the flux linkage characteristics. The current minimization based optimal current control is achieved. When torque feedforward control is applied, the machine output performance, including torque capability, torque accuracy, efficiency and current transition are validated. Thermal performance of the machine is evaluated under continuous power operation and peak power operation. The FEA based thermal model is developed and calibrated using steady state experimental results. The transient thermal performance is studied by simulations and verified by experiments.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)


contributor:
Straus, J.
Engineering Physics

abstract: Title: Wavelength Division Multiplexed Optical Fibre System, Author: William J. Sinclair, Location: Thode

abstract:
The design, construction techniques and results of
evaluation of two types of optical fibre multiplexing and
demultiplexing devices are given.

The first type of device is a three channel optical
multiplexer/demultiplexer operating in the 750 to 900 nm band.
This device allows the simultaneous transmission of 3 different
wavelengths through the same optical fibre. It employs a diffraction
grating, in the Littrow configuration, as the wavelength
selective element. The device is compact and rugged due to the
use of a gradient index lens to which the other assemblies are
cemented. The wavelength channels have centre wavelengths of
790, 830 and 870 nm and are nominally 30 nm wide at the -1 dB
points. The loss is 2.2 to 2.5 dB when used as a demultiplexer
and 7 to 8 dB when used as a multiplexer. Crosstalk is less than
-30 dB at the channel centres.

The other device is a two channel multiplexer-demultiplexer
which allows a bidirectional system to be constructed. This
device has a short wavelength channel from 770 to 890 nm and a
long wavelength channel from 1100 to 1400 nm. It employs an
interference filter as the wavelength selective element. The
filter is cemented between two gradient index lenses to form a
compact rugged device. The loss is 1.5 dB for the 770 to 890 nm
wavelength channel and 3.5 dB for the 1100 to 1400 nm wavelength
channel.

Combining the two and three channel devices results in a
four channel bidirectional system for use in integrated
distribution services.

Suggestions for improvements in the design and construction
of the devices are also given.

abstract: Thesis

abstract: Master of Engineering (ME)


title: Depositional Mechanics of Atypical Turbidites, Cloridorme Formation, Gaspé, Quebec

contributor:
Middleton, G. V.
Geology

subject: depositional mechanics, atypical, turbidites, cloridorme formation, sediment, laminae

abstract:
 Thick turbidite beds, belonging to the β1 member, Cloridorme Formation (Ordovician), are exposed on the wavecut platform between St. Hélier and Fame Point, Gaspé, Quebec. The local paleocurrent direction (to the west) is approximately parallel to the east-west strike of the vertical beds.

 These thick turbidite beds display a sequence of sedimentary
structures which differs from the sequence defined by Bouma. Three broad divisions are recognised: a basal division consists of either limestone or quartz granule to pebble conglomerate (0-4 cms thick) or coarse sand greywacke or calcareous wacke (0-15 cms thick).
Basal divisions of calcareous wacke frequently display ripple-lamination, parallel lamination, or upstream inclined laminae. Where the upstream inclined laminae form a single set, they occur below a sinuous profile (wavelength 40-80 cms, and amplitude 2-5 cms).

 A second division (0-330 cms thick) consists in most places of spindle or globular shaped calcareous nodules scattered in an argillaceous matrix. In some beds streaking and lobing of light coloured carbonate bearing material is associated with these nodules. The upper division consists of fine grained siltstone and shale.

 Thick broken blocks which have fallen from the cliffs, display the internal characteristics of the second division. Hemi-ellipsoid
structures, arranged en echelon and convex towards the base of the bed, are displayed by one block.

 The upstream inclined laminae in the basal divisions of calcareous wacke beds are interpreted as the result of the upstream migration of antidunes. The nodules within the second division developed as 'pseudonodules'. The hemi-ellipsoid structures resemble damped
large scale (macroturbulent) eddies associated with the flow of dense grain dispersions. The directions of the internal motions are shown by the orientation of grains and graptolite stipes.

 Correlation of these beds has been achieved over a distance of 7-1/2 miles. Over this distance the beds show little change in their characteristics. Basal divisions of granule and pebble conglomerate persist over this distance and show that coarse particles may be transported by turbidity currents over long distances. The sedimentary structures of the basal divisions of several calcareous wacke beds give the appearance (probably misleading) of an increase in flow regime downcurrent.

 The beds were probably deposited from initially low concentration but high density turbidity currents accompanied by a period of coarse grain traction and suspension near to the bed. In the case of calcareous wacke beds this period of traction formed rippled, flat or antidune bed forms. Stratification has been preserved by the rapid deposition of sediment en masse from the subsequent high concentration body of the current. The formation of a succession of 'quick' beds led to the sedimentation of the second division.

 Calculations suggest that the currents moved over slopes of much less than 1°.

abstract: Thesis

abstract: Master of Science (MSc)


title: EXPLORING PERIPHERAL FACTORS IMPACTING SEXUAL DIMROPHISM OF THE BED NUCLEUS OF THE STRIA TERMINALIS

contributor:
Foster, Jane A.
Neuroscience

subject:
AMH
Microglia
T lymphocytes
Bed nucleus of the stria terminalis

abstract: Immune-brain-endocrine communication influences behaviour and contributes to the development of the central nervous system (CNS) in a sexually dimorphic manner. The bed nucleus of the stria terminalis (BST) is a highly sexually dimorphic brain region; in most mammalian species the male BST is larger than the female BST. Previously, our lab has shown that male and female mice lacking T cells due to knock out of the beta (b) and delta (d) chains of the T cell receptor (TCRb-/-d-/-) have reduced anxiety-like behaviour. This was shown with increased time spent in the open arms of the elevated plus maze by TCRb-/-d-/- mice compared to wild type (WT) mice of both sexes. T cell deficient mice also show differences in brain volume compared to WT, including a lack of sexual dimorphism in volume of the BST. The present study explored the impact of T cell deficiency on immune and endocrine factors implicated in sex differences of the CNS. The first analysis was of serum Anti-Müllerian hormone (AMH). AMH is a key determinant of the male phenotype during fetal development. It has also been shown by others to contribute to sexual dimorphic development of the BST. Our postnatal analysis of serum AMH using ELISA demonstrated an age and genotype effect, where a peak in serum AMH levels in WT mice of both sexes was absent in both male and female TCRb-/-d-/- mice at postnatal day (P) 7. These results suggest that T cells have an impact on the endocrine system in early life but the process does not appear to be sexually dimorphic. The present study also explored the impact of TCR knockout on microglia, the resident immune cells of the brain. Other have shown microglia contribute to sexual dimorphic brain development. This contribution occurs through interaction with endocrine factors, making them a key player in the immune-brain-endocrine crosstalk. Using immunohistochemistry and the microglial marker, anti-Iba1, microglia were examined in adult and P7 WT and TCRb-/-d-/ mice.  To quantify microglia, soma were traced using AxioVision microscope software, and microglia cell number, perimeter, radius, feret ratio, and area in dorsal and ventral BST were assessed. Our results show sex differences in microglia number in dorsal BST in adult WT mice, where female WT mice had a lower number of microglia compared to WT males, however this difference was absent in TCRb-/-d-/- adult mice. There were no effects on microglia number in the ventral BST and morphology analysis did not reveal any effects in the dorsal or ventral BST. Furthermore, the difference in microglia number was absent in all groups of P7 mice and analysis of soma morphology did not reveal any significant effects. This study explored the impact of TCR knockout on the BST by exploring the immune and endocrine factors shown to contribute to its sexual dimorphic development. The results suggest a non-dimorphic impact on the endocrine system in the postnatal period and a dimorphic impact on microglia that is age and region-specific. The findings reveal a complex network emphasizing the importance of a systems-wide approach to the study of sex differences in the CNS.

abstract: Thesis

abstract: Master of Science (MSc)


title: SYNTHESIS OF NOVEL PET AND FLUORESCENT PROBES FOR THE MOLECULAR IMAGING OF RHEUMATOID ARTHRITIS AND CANCER

contributor:
Valliant, John
Chemical Biology

abstract:
This thesis describes novel molecular imaging strategies that can ultimately be used for imaging rheumatoid arthritis (RA) and cancer. In the first approach, a convenient method for the preparation of a “turn on” near-infrared (NIR) optical reactive oxygen species (ROS) probe and its 18F analogue is described. The probe and its radiolabeling precursor are prepared in high yield (82 and 98% respectively) via a Suzuki coupling in two steps. Chemical induction studies revealed the probe selectively responds to hydroxyl and superoxide radicals. The PET probe was accessed via a late-stage fluorination approach from a nitropyridine precursor in a 62% decay-corrected radiochemical yield. As a proof of concept, the PET probe was assessed in vivo in C57BL/6 mice using a doxorubicin induced model of cardiac ROS which revealed a statistically significant retention in the heart as compared to untreated mice (p ˂ 0.05). The probe additionally demonstrated high-blood retention in vivo, which is likely due to albumin binding. Less hydrophobic derivatives of this probe were synthesized in a similar approach with the ultimate goal of improving in vivo clearance.
Building on this work, the synthesis of a meso fluorinated cyanine dye derived from copper-catalyzed halogen exchange of IR780 iodide is discussed. Optimized reaction conditions led to a 68% yield in the presence of a phosphaadamantane ligand and a copper (II) catalyst. The fluorinated probe exhibited enhanced fluorescence in comparison to IR780 in solution. The corresponding ROS probes (hydrocyanines) were assessed in a PC-3 cell assay where the fluorinated probe exhibited 2-3 fold fluorescence enhancement. Radiolabeling to produce the 18F analogue was attempted, but this was found to be irreproducible. This fluorinated dye along with IR780 and other synthesized fluorescent probes were encapsulated in F-127 micelles which resulted in the preparation of monodispersed micelles (PDI ≤ 0.2). Improved solubility and fluorescence were observed as compared with unencapsulated dyes. An MTT assay performed on the encapsulated ROS probe revealed it was considerably less cytotoxic than the parent probe.
Alternatively, a targeted approach via the development of molecular probes based on two classes of high affinity TACE enzyme inhibitors is described. Three compounds were synthesized and assessed in a fluorogenic assay in which one compound demonstrated binding in the micromolar range (IC50 = 1770 nM) while the remaining compounds demonstrated low nanomolar affinity (IC50 = 5-10 nM). Intermediates that could serve as precursors in 18F labeling via a prosthetic group labeling strategy were prepared.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


contributor:
Kardos, G.
Mechanical Engineering

abstract: Title: Plastic Strain in Materials Under the Influence of Impulsive Load, Author: Shailendra K. Sinha, Location: Thode

abstract:
Equipment was designed for testing dynamic behaviors of materials subjected to impulsive load.

Detail design of the equipment and experimental techniques have been described.

Armco Ingot Iron with 99.8% purity was tested. Before testing, the material was fully annealled.

"n" and "G(ε,t) (as occurring in the characteristic equation σm^n to K(n) = G (ε,t), for this material were evaluated.

The material was found to ber very sensitive to strain rates.

abstract: Thesis

abstract: Master of Engineering (ME)


contributor:
Ives, M.B.
Physics

abstract: Title: On the Dissolution Characteristics of Kr-Bombardment Lithium Flouride, Author: Binoy K. Sinha, Location: Thode

abstract:
A study has been made of crystal dissolution of Kr-bombarded lithium flouride in aqueous solutions of ferric chloride. Bombarded surfaces were observed to have a higher dissolution rate than the non-bombarded ones, the dissolution rate itself being a function of ion-concentration. A bombarded and annealed surface was found to have an even higher dissolution rate than a bombarded surface.

Nucleation of pits was observed to depend on the dose of bombardment, A dose of 10^5 and 10^6 ions/cm^2 caused uniform dissolution of the surface without any pit-formation but a dose of 10^13 and 10^14 ions/cm^2 was found to cause pitting even in the radiation damage as indicated by the activity of the radioactive krypton. In the former case uniform dissolution is explained by the relative increase in the density of Frenkel defects.

abstract: Thesis

abstract: Master of Science (MS)


title: Rocking the Inflationary Boat: Looking at the sensitivity to initial conditions of solutions to novel inflationary scenarios

subject:
Cosmology
Inflation
Particle Physics
Extra Dimensions

abstract:
Inflation, the currently favoured solution to the grievous initial conditions problems of the Big Bang model of the universe, is a very general framework that can be constructed from any number of underlying theories. As inflation is meant to solve a problem of initial conditions, it is generally preferred that it not introduce its own initial conditions problem. The purpose of this thesis is to explore the sensitivity to initial conditions of solutions to two toy models of inflation. The models in and of themselves are not intended to explain inflation, but rather seek to begin to explore, in a controlled way, interesting properties that a full inflationary theory might have.
The first model is one with a single scalar inflaton, but two compact extra dimensions. We find this model has two inflationary solutions that can be well understood analytically. These solutions are power laws in time. One is found to be marginally insensitive to its initial conditions, and the other is found to be highly sensitive to its initial conditions. We also find a solution to this model that exhibits 4D quasi-de Sitter space, but is difficult to understand analytically, and its sensitivity to initial conditions is not yet well known.
The second model examines an n-scalar field Lagrangian that includes kinetic terms first-order in the derivatives of the fields (similar to certain ferromagnetic Lagrangians). It is found that this model can realize slow-roll inflation with arbitrarily steep potentials. A solution is constructed that can realize an exact de Sitter equation of state without saying anything about the slope of its potential. This solution is found to be marginally insensitive to its initial conditions for a certain range of parameters. Corrections from higher order terms in the Lagrangian are found to introduce a parameter space for which this solution is in fact highly insensitive to its initial conditions.
We therefore make progress in understanding higher-dimensional inflation, slow-roll inflation with steep potentials, and the sensitivity of solutions in both those cases to their initial conditions.

abstract: Thesis

abstract: Master of Science (MSc)


title: Redistributive Non-Dissipative Battery Balancing Systems with Isolated DC/DC Converters: Theory, Design, Control and Implementation

subject:
Control strategy
electric vehicle
model predictive control
hybrid vehicle
MPC
LQR
Lithium-ion battery
Redistributive cell balancing
Active Balancing
Linear Quadratic Regulator
Rule based control
Control
Non-dissipative
Passive Balancing

abstract: Energy storage systems with many Lithium Ion battery cells per string require sophisticated balancing hardware due to individual cells having manufacturing inconsistencies, different self discharge rates, internal resistances and temperature variations. For capacity maximization, safe operation, and extended lifetime, battery balancing is required. Redistributive Non-Dissipative balancing further improves the pack capacity and efficiency over a Dissipative approach where energy is wasted as heat across shunt resistors. Redistribution techniques dynamically shuttle charge to and from weak cells during operation such that all of the stored energy in the stack is utilized. This thesis identifies and develops different balancing control methods. These methods include a unconstrained optimization problem using a Linear Quadratic Regulator (LQR) and a constrained optimization problem using Model Predictive Control (MPC). These methods are benchmarked against traditional rule based (RB) balancing. The control systems are developed using MATLAB/Simulink and validated experimentally on a multiple transformer individual cell to stack topology. The implementation uses a DC2100A Demo-board from Linear Technology with bi-directional flyback converters to transfer the energy between the cells. The results of this thesis show that the MPC control method has the highest balancing efficiency and minimum balancing time.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Methodology and Application of Metagenomics for the Characterization of Bacterial Populations in Aquatic Environments

contributor:
Golding, Brian
Biology

subject:
Metagenomics
Bioinformatics
Computational Biology
Microbial Ecology

abstract: Metagenomics is a culture-independent framework for deciphering the complexity of biological communities, often with a focus on microbial communities in a specific environment. The applicability of this approach is widespread due to the ubiquity and presence of unculturable microbes in many environments which can only be investigated using culture-independent methods. With advances in DNA sequencing and the introduction of high-throughput sequencing technologies, studying microbial life as communities has become more accessible. However, the breadth of data generated dictates that computational processing steps must be in place to analyze the data. Due to the large diversity in computational and bioinformatic steps possible for metagenomic data, differences in methods of analysis can lead to discordant interpretations of results. The performance of different metagenomics methods must therefore be assessed to establish the effect on the interpretation of results. Taxonomic classification is an integral step in metagenomic analysis and many tools exist for this purpose. To determine which tools are better suited for particular types of metagenomic data, a comparative analysis of performance was conducted for numerous tools. The findings suggest that hybrid programs may have the best performance and warrant further investigation. Programs such as CLARK, KRAKEN, and MEGAN also performed well and are suitable for metagenomic analysis. Utilizing these methods, investigation into the bacterial populations of four freshwater beaches was examined. Bacterial communities in beach waters and sands were more distinct in terms of taxonomic composition than communities in different lakes. Functional capacity was stable between beach habitats, although enrichment of anaerobic and stress related genes in the sand suggests that this is a relatively harsh environment. The detection of sequences belonging to pathogens in the sands of these beaches also has implications for public health and warrants changes in water quality monitoring procedures.

abstract: Thesis

abstract: Master of Science (MSc)


title: Peripheral and Central Factors in Tinnitus

contributor:
Roberts, Larry
Bruce, Ian
Psychology

abstract: Tinnitus is the phantom perception of a sound heard in the absence of a physical sound source. One framework that attempts to explain tinnitus is called the deafferentation model, which asserts that hearing damage precipitates compensatory neural plasticity in the central auditory system, leading to hyperactivity perceived as tinnitus. While considerable evidence supports this view, the role of deafferentation and its effects on central auditory processing are not fully understood. This thesis addresses two questions raised within the model. First, audiometric hearing loss is not always present in tinnitus subjects, so is there evidence of deafferentation in these individuals? The second question concerns the effect of tinnitus with audiometric hearing loss on central auditory processing. Specifically, is auditory attention affected in tinnitus, and if so, how?  Following a background review in Chapter 1, Chapter 2 describes a study addressing the first issue, which found evidence for previously undetected hearing loss in tinnitus subjects that distinguishes them from individuals with normal hearing. Chapter 3 addresses the second question, describing an investigation that found that top-down attention appears to operate normally in tinnitus, but the tinnitus-affected region of auditory cortex is insensitive to the influence of attention because it is busy encoding the tinnitus. Chapter 4 describes a background study using non-tinnitus individuals to test this latter conclusion, finding evidence that auditory cortical neurons reacting to stimulus change are concurrently sensitive to top-down attention. This procedure can be used to assess if tinnitus-affected auditory cortical neurons are generally insensitive to input. Chapter 5 discusses the implications of the above empirical findings for understanding the role of deafferentation in tinnitus and tinnitus-related changes that occur in central auditory processing.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)


title: Cyborgification and the Disabled Body

contributor:
Gedge, Elisabeth
Philosophy

subject: Bioethics Cyborg Disability Ethics Feminism Philosophy

abstract: In this thesis, I examine traditional philosophical arguments concerning the disabled body. I contribute to disability theory by focusing on disabled individuals who employ the use of advanced prosthetics, and by looking at the implications of said prosthetics on disabled individuals’ lived experiences and the ideology of disability. I join other thinkers in finding current disability theory inadequate in its attempts to accurately describe disability and aid disabled individuals to flourish and resist discrimination and marginalization. I suggest that advanced prosthetic use by disabled persons results in the overt cyborgification of the disabled body. Furthermore, I suggest that the cyborgification of the disabled body requires us to re-evaluate the binary of ability vs. disability, and requires us to stop essentializing the disabled body as disabled. I suggest therefore, that these new technologies should be considered morally permissible, and respond to possible objections from the standpoints of fairness and from concerns more broadly regarding transhumanism. Ultimately, questions remain as to any regulatory schemes that should possibly be put in place regarding advanced prosthetics to either limit or promote access to advanced prosthetic technologies for various groups, and to what degree disabled persons should be able to draw on medical resources to access advanced prosthetics.

abstract: Thesis

abstract: Master of Arts (MA)

abstract: In this thesis I aim at unpacking the ways in which traditional theories about disability fail to view the disabled body in an accurate way. I examine the advance of prosthetic technologies as they relate to disability and suggest that in this way the disabled person is a very good example of a cyborg. I then apply cyborg ideologies to ideas of disability and suggest the cyborgification of the disabled body is beneficial both from a flourishing and an ideological standpoint. I finally consider and respond to some objections against advanced prosthetics and transhumanism more broadly.


title: The type IVa pilus machine is pre-installed during cell division

contributor:
Burrows, Lori
Biochemistry and Biomedical Sciences

subject:
Type IV pili
Gram negative cell envelope integration
polar localization

abstract: Type IV pili (T4P) are protein filaments found on the surface of a variety of bacterial species and mediate biofilm formation, adhesion, and flagellum-independent twitching motility. The biogenesis of T4P is dependent on a cell envelope-spanning, multiprotein complex that localizes to the poles in rod-shaped cells. How these proteins localize and cross the peptidoglycan (PG) layer in the absence of dedicated PG-hydrolyzing enzymes is unknown. In P. aeruginosa, PilMNOP interact to form the alignment subcomplex, connected via PilP to PilQ, which forms the outer membrane secretin. We hypothesized that polar localization and integration of the T4P machinery was driven by ordered recruitment to future sites of cell division, placing assembly system components at division septa in the correct position before daughter-cell separation. To determine which T4P components are essential for localization of the complex, we fused the T4P inner membrane assembly protein PilO to the fluorescent protein mCherry to monitor its localization. mCherry-PilO localized to the cell poles and midcell in wild type bacteria. However, it was delocalized in a strain lacking PilQ. A PilQ-mCherry fusion localized to the cell poles, likely through its putative septal PG binding AmiN domains, suggesting that PilQ binds PG and thus localizes its partners to future sites of cell division. In the absence of the associated pilotin protein (PilF), which is required for PilQ multimerization in the OM, T4P components were polarly localized, implying that localization is not dependent on secretin formation. The results of this research support a pre-installation mechanism for integration of protein complexes in the gram negative cell envelope without PG hydrolysis, which may be applicable to other systems.

abstract: Thesis

abstract: Master of Science (MSc)


title: Utilizing Ground Level Remote Sensing to Monitor Peatland Disturbance

contributor:
Waddington, James Michael
Earth and Environmental Sciences

subject:
remote sensing
peatlands
sphagnum
ecohydrology
GIS
chlorophyll fluorescense

abstract:
This study examined the usefulness of remote sensing to monitor peatlands, and more specifically Sphagnum moss ‘health’.  Results from this study show that thermal imaging can be used to monitor Sphagnum productivity, as when the surface temperature of Sphagnum exceeds a threshold value (30.8 °C in the field and 18.2 °C in the laboratory), Sphagnum quickly changes from being productive to being unproductive.  The Enhanced Normalized Difference Vegetation Index (ENDVI) can also be used in a similar manner, where if the ENDVI value is high (above 0.11 in the field and -0.12 in the laboratory), Sphagnum will be productive, and otherwise, it will be stressed.
A classification scheme was developed to monitor peatland recovery to fire disturbance.  By utilizing the ENDVI, leaf area index and aboveground biomass within a recovering peatland can be mapped, as well as the recovery trajectory of the groundcover.  The findings of this study highlight the potential use of remote sensing to assess the driving factors of Sphagnum moss stress, as well as quickly and expansively aid in peatland recovery trajectory.

abstract: Thesis

abstract: Master of Science (MSc)


contributor:
Sprung, Donald W.L.
Physics

abstract: Title: Deviations of Tensor Force Strength from OPEP Values, Author: Rohitashva, Location: Thode

abstract: This thesis presents a study of experimental evidence for the depth of the tensor force in the region 1.5 to 3.0fms.< assuming the One-Pion-Exchange Potential (OPEP) beyond. The interest in this question is related to the fitting of a velocity dependent potential, for radii <1.5fm., for use in many-body calculations. The method employed is to examine effects on the observables of tensor force splitting in the phase-shifts for proton-proton scattering. It was found that the data favour a tensor force very close to the OPEP in the region studied.

abstract: Thesis

abstract: Master of Science (MS)


title: Three Essays In Industrial Organization, Law And Finance

contributor:
Chamberlain, Trevor
Business

subject:
Capital structure
Law and finance
Industrial organization
International capital markets

abstract:
This thesis explores three important topics spanning international asset pricing, empirical capital structure, U.S. politics, and corporate law: relationship-specific investment (RSI), contracting environment and financial performance; RSI, contracting environment and the choice of capital structure; and political value and SEC enforcement actions.
Firms that engage in long-term bilateral relationships with their buyers or suppliers are usually required to make relationship-specific investments. We examine how the values of these long-term specific investments are affected by the quality of governmental contract enforcement. We find that firms in relationship-specific industries have higher valuations, measured by Tobin’s Q, when their countries of origin are able to strongly enforce contractual agreements. Our finding is robust to a variety of empirical specifications and regression methods. We also show that as legal quality improves, firms with relationship-specific investments exhibit lower operating performance, presumably due to risk or in order to motivate further investments from their stakeholders. Further analysis of the cross-section of stock returns supports a risk-based explanation.
Firms in long-term bilateral relationships with their customers or suppliers are required to make relationship-specific investments in the form of physical equipment, human resources, specific production sites, or brand names. These dedicated assets are usually tied to a particular use or relationship and cannot be redeployed if the firm is liquidated. In the absence of legal enforcement, firms are required to limit their use of debt financing and, consequently, signal a reduced default risk to encourage investment by their contracting parties. Using a sample of 143,278 firm-year observations, and measures of industry-level relationship-specificity and the quality of legal enforcement across 57 countries, we find strong evidence that good quality contract enforcement mitigates the negative association between relationship-specificity and debt financing.
The Securities and Exchange Commission (SEC) plays a central role in investigating potential violations of securities laws and initiating enforcement actions in the United States. We examine the association between political culture and political connections and the penalties imposed at the end of SEC enforcement actions. Our analysis is based on two key ideas. First, the political culture of a firm indicates its ethical boundaries and explains the propensity of misconduct across different domains, such as securities laws. Second, political connections signal a firm’s willingness to challenge SEC’s enforcement decisions. We find that the individual defendants associated with Republican firms are less likely to receive a bar or suspension penalty. This finding supports the notion that Republican managers are less likely to commit securities fraud since the Republican ideology stresses market discipline. Moreover, in line with prior research, our results show that political connections and firm size, as a proxy for bargaining power, also reduce penalties imposed in SEC enforcement actions.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: The Spatial Theory of Linear Elastic Members by Direct Kinematic Method

contributor:
Oravas, G. AE.
Civil Engineering

subject: spatial theory, linear, elastic, kinematic, direct, members, displacement

abstract: In this work the direct, kinematic, small-displacement theory has been developed for the analysis of thin, elastic members which are curved and twisted in their natural configurations. Principles of continuum mechanics have been used to derive the equations of equilibrium. Throughout this investigation the three-dimensional aspect of the problem is preserved. Local kinematic compatibility of the displacement field has been investigated by the formal Saint-Venant's method. This development serves to substantiate the validity of the kinematic tridimensional approach. By the judicious neglection of small terms of higher order throughout this analysis, the basic system of equations arrived at by the author admit favourable comparison with the existing equations by other authors.

abstract: Thesis

abstract: Master of Engineering (MEngr)


title: Transient Stability of the Wien Bridge Oscillator

contributor:
Gladwin, A. S.
Electrical Engineering

subject: transient stability, Wien Bridge, oscillator, resistor

abstract:
In many Resistance-Capacitance Oscillators the oscillation amplitude is controlled by the use of a temperature-dependent resistor incorporated in the negative feedback loop. The use of thermistors and tungsten lamps is discussed and an approximate analysis is presented for the behaviour of the tungsten lamp. The result is applied in an analysis of the familiar Wien Bridge Oscillator both for the presence of a linear circuit and a cubic nonlinearity. The linear analysis leads to a highly unstable transient response which is uncommon to most oscillators.
The inclusion of the slight cubic nonlinearity, however, leads to a result which is in close agreement to the observed response.

abstract: Thesis

abstract: Master of Engineering (MEngr)


title: METHODOLOGICAL ISSUES IN PREDICTION MODELS AND DATA ANALYSES USING OBSERVATIONAL AND CLINICAL TRIAL DATA

contributor: Clinical Epidemiology/Clinical Epidemiology & Biostatistics

subject:
PREDICTION MODEL
OBSERVATIONAL DATA
CLINICAL TRIAL
DATA ANALYSIS

abstract:
Background and objectives:
Prediction models are useful tools in clinical practise by providing predictive estimates of
outcome probabilities to aid in decision making. As biomedical research advances, concerns
have been raised regarding combined effectiveness (benefit) and safety (harm) outcomes in a
prediction model, while typically different prediction models only focus on predictions of
separate outcomes. A second issue is that, evidence also reveals poor predictive accuracy in
different populations and settings for some prediction models, requiring model calibration or
redevelopment. A third issue in data analyses is whether the treatment effect estimates could
be influenced by competing risk bias. If other events preclude the outcomes of interest, these
events would compete with the outcomes and thus fundamentally change the probability of
the outcomes of interest. Failure to recognize the existence of competing risk or to account
for it may result in misleading conclusions in health research. Therefore in this thesis, we
explored three methodological issues in prediction models and data analyses by: (1)
developing and externally validating a prediction model for patients’ individual combined
benefit and harm outcomes (stroke with no major bleeding, major bleeding with no stroke,
neither event, or both stroke and major bleeding) with and without warfarin therapy for atrial
fibrillation; (2) constructing a prediction model for hospital mortality in medical-surgical
critically ill patients; and (3) performing a competing risk analysis to assess the efficacy of
the low molecular weight heparin dalteparin versus unfractionated heparin in venous
thromboembolism in medical-surgical critically ill patients.
Methods:
Project 1: Using the Kaiser Permanente Colorado (KPCO) anticoagulation management
cohort in the Denver-Boulder metropolitan area of Colorado in the United States to include
patients with AF who were and were not prescribed warfarin therapy, we used a new
approach to build a prediction model of individual combined benefit and harm outcomes
related to warfarin therapy (stroke with no major bleeding, major bleeding with no stroke, neither event, or both stroke and major bleeding) in patients with AF. We utilized a
polytomous logistic regression (PLR) model to identify risk factors and then construct the
new prediction model. Model performances and validation were evaluated systematically in
the study.
Project 2: We used data from a multicenter randomized controlled trial named Prophylaxis for
Thromboembolism in Critical Care Trial (PROTECT) to develop a new prediction model for
hospital mortality in critically ill medical-surgical patients receiving heparin
thromboprophylaxis. We first identified risk factors independent of APACHE (Acute
Physiology and Chronic Health Evaluation) II score for hospital mortality, and then combined
the identified risk factors and APACHE II score to build the new prediction model. Model
performances were compared between the new prediction model and the APACHE II score.
Project 3: We re-analyzed the data from PROTECT to perform a sensitivity analysis based on
a competing risk analysis to investigate the efficacy of dalteparin versus unfractionated
heparin in preventing venous thromboembolism in medical-surgical critically ill patients,
taking all-cause death as a competing risk for venous thromboembolism. Results from the
competing risk analysis were compared with findings from the cause-specific analysis.
Results and Conclusions:
Project 1: The PLR model could simultaneously predict risk of individual combined benefit
and harm outcomes in patients with and without warfarin therapy for AF. The prediction
model was a good fit, had acceptable discrimination and calibration, and was internally and
externally validated. Should this approach be validated in other patient populations, it has
potential advantages over existing risk stratification approaches.
Project 2: The new model combining other risk factors and APACHE II score was a good fit,
well calibrated and internally validated. However, the discriminative ability of the prediction
model was not satisfactory. Compared with the APACHE II score alone, the new prediction
model increased data collection, was more complex but did not substantially improve discriminative ability.
Project 3: The competing risk analysis yielded no significant effect of dalteparin compared
with unfractionated heparin on proximal leg deep vein thromboses, but a lower risk of
pulmonary embolism in critically ill medical-surgical patients. Findings from the competing
risk analysis were similar to results from the cause-specific analysis.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: The interplay between microbial dysbiosis and immune dysfunction with age

contributor:
Bowdish, Dawn
Medical Sciences

subject:
Microbiome
Immunology
Aging
Gnotobiotic
Gut permeability
Illumina Sequencing

abstract: It is well known that the elderly often manifest chronic low-grade inflammation. This phenomenon, called “inflamm-aging,” is postulated to contribute to increased susceptibility towards infectious diseases and an overall increase in frailty. We have proposed examining the gut microbiome as a potential mediator of these changes. Gut microbial communities influence the host immune system; often dictating an individual’s health status. Thus, harmful gut microbiome changes, termed dysbiosis, are associated with poor health in the elderly. We first sought to understand the key immunological, physiological and microbiome changes occurring with age (Chapter 3). Our data reveals immune impairments in aged mice, with increased intestinal permeability, systemic inflammation and alterations in the functions of myeloid cell populations. However, our aged germ-free (GF) mice are protected from these outcomes, indicating that the old microbiome may play a strong role in these age-associated impairments. To study this further, we have colonized young and old GF mice with the “young” or “old” microbiota in order to determine whether the relationship between microbial dysbiosis with age and health status is correlative or causative (Chapter 4). Interestingly, young GF mice colonized with old microbiota have significantly increased permeability, systemic inflammation and an influx of Ly6Chigh monocytes when compared to those colonized with the young microbiota. By using transgenic mice (TNF-/- mice), or by reducing systemic TNF levels via therapeutics, we were able to reduce some aspects of microbial dysbiosis and age-associated inflammation (Chapter 5). Our data suggests that harmful changes to the gut microbiome composition with age initiate a cycle of negative events that ultimately result in increased inflammatory myeloid cell recruitment, increased intestinal permeability and an overall increase in systemic inflammation in old mice. By identifying these key changes, we can work towards developing effective therapeutics that promotes healthy aging and protection against infectious diseases.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: Élie Metchnikoff first coined the term “dysbiosis” when he described the imbalance in microbial populations that could result anywhere in the body. Since then, numerous studies have examined the role of the intestinal microbiota in defense against pathogens. Metchnikoff also suggested that the gut composition and function is altered with age and this can in turn; increase the host’s susceptibility towards infectious diseases. My research aims to characterize the role of microbial dysbiosis on the immune defects with age. To do so, I will be utilizing a unique set of mice, called gnotobiotic mice. These mice are housed under specific germ-free conditions and contain no microbiome. Thus, they provide us with the ideal model to study the effects of the microbiome on immune function. The findings from these studies will help in the development of preventative and therapeutic alternatives to provide the elderly with more years of healthy, independent living.


title: Thresholds to XE-135 Induced Flux Oscillations in the Pickering and Bruce Nuclear Power Reactors (Part A) / Arc Trimming of Nichrome Thin Film Microcircuits (Part B)

contributor:
Trojan, O. A.
Shewchun, J.

subject: trimming, thin-film, nichrome, microcircuits, resistors, Pickering and Bruce cores, flux, thresholds, oscillations, nuclear power

abstract: This thesis contains both Parts A and B.

abstract:
 Xenon induced flux oscillations are possible in large thermal reactors operating at high powers because of the inter-play between the xenon concentration, reactivity, and thermal flux, and the fact that xenon is produced mainly by radioactive decay of I-135, which has a half-life of 6.7 hours. Due to these nuclear characteristics along with size and operating conditions of the Pickering and Bruce cores, these oscillations in flux are inherently unstable with respect to xenon. That is, a local perturbation in reactivity will result in a divergent and cyclic time and space variation in the thermal flux distribution in the core.

 One group diffusion theory and a simple perturbation analysis yield for a bare thermal reactor, a threshold in the average flux level ∅ which satisfies (1) M^2λij^2 / αxe - αT/αxe ∅ = 1/1+λxe/σxe∅ - μxe / 1+(λxe + λ1)/σxe∅ for oscillations in ijth mode of the flux distribution (see Figure 1) M^2 is the migration area in cm^2, αxe is the reactivity load of Xe-135 at high flux levels; αT is the fuel temperature coefficient expressed in terms of reactivity change per unit flux. The function f(∅) depends only upon the decay constants λxe of Xe-135 and λ1 of I-135; μxe is the fraction of Xe-135 produced directly from the fission of the fuel rather than through iodine decay (which fraction is denoted by μ1). The dimensionless parameter λij^2 depends only upon the shape of the flux distribution and is equal to the difference between the bulking of the ijth mode and the fundamental model.

 The Bruce and Pickering reactors are used as models in this study to determine the threshold power level at which xenon instability is possible and in which mode this instability occurs.

 Bruce is found to be unstable in the fundamental and first azimuthal mode for fresh and equilibrium fuel conditions, and stable for the radial, axial and higher azimuthal modes.

 Pickering, on the other hand, is unstable for the equilibrium fuel condition in the fundamental and first azimuthal modes only and is stable in every mode except the fundamental in the fresh fuel condition.
 (Part A of Thesis)-------------------------------------------------------------------------------------------------------(Part B of Thesis)
 Trimming of thin-film resistor components by an electrical arc is investigated in this report as an inexpensive and simple alternative to the laser trim and mechanical scribe methods. A multitude of tests were effected on Garrett Manufacturing Limited production circuits containing nichrome thin film resistors. These tests included Temperature Coefficient of Resistivity, resistance stability, substrate damage, noise performance, dynamic trim with active devices operating, width of cut as compared to mechanical scribe and laser trim techniques, and optimum parameters for trimming. In all cases the trimmed circuits were within the design specifications of the resistor properties under test. It is the conclusion of the author that the obvious attributes of the arc-trim method as well as its outstanding performance in the above tests, warrants its serious
consideration as a viable alternative to the laser trim and mechanical scribe methods of altering resistance levels.

abstract: Thesis

abstract: Master of Engineering (MEngr)


title: Singing Voice Attractiveness

title: The Attractiveness of the Singing Voice in Women

contributor:
Feinberg, David
Psychology

subject: singing attractiveness, voice pitch, pitch accuracy, rhythm accuracy

abstract: Previous experiments have shown that voice pitch (the perception of fundamental frequency and/or corresponding harmonics) is positively associated with women’s voice attractiveness, however all of this research is on women’s speaking voices. Singing is important for the mating success of non-human animals, is cross-culturally universal in humans, and is highly sexualized in many cultures. Thus, singing could contribute to mating success and attraction in humans. First, we investigated whether previous findings, that high voice pitch when speaking predicts women’s voice attractiveness, extend to when women sing. We also examined whether pitch- and rhythm accuracy contribute to women’s singing voice attractiveness. Voice pitch was positively related to women’s singing voice attractiveness as judged by men more than when judged by women, and speaking voice attractiveness was positively related to singing voice attractiveness. Thus, men and women may be reacting to the same indicator of women’s underlying quality (i.e. voice pitch) in both women’s speaking and singing voices, differently. Men may be attracted to high pitch, whereas women may show a weaker relationship, as they tend to be more romantically jealous of women with high pitched voices. Pitch- and rhythm accuracy did not predict women’s singing voice attractiveness. This result can be interpreted in different ways. It could mean that women’s voice pitch may be more important in determining men’s perceptions of their singing voice attractiveness than is their singing ability, or our measures were ill suited to the task. Collectively, these results are the first to show that singing voices are more attractive than speaking voices, people with attractive speaking voices tend to have attractive singing voices, and that singing and speaking voices relate to the same underlying qualities. Thus, singing may be an indicator of mate value and could have played a role in the evolution of sex differences in the voice if our ancestors had similar preferences.

abstract: Thesis

abstract: Master of Science (MSc)


title: Synthesis and Characterization of In Situ Gelling Hydrogels Made From Hyperbranched Poly(oligoethylene glycol methacrylate)

contributor:
Hoare, Todd
Chemical Engineering

subject: POEGMA hydrogels polymers hyperbranched

abstract: Hydrogels have attracted interest as biomaterials due to their similarity to native tissue and extracellular matrix as well as their versatility and tunability. Each of these characteristics allows hydrogels to be used in a wide variety of biomedical applications including drug delivery, tissue engineering, and regenerative medicine. Poly(oligoethylene glycol methacrylate) (POEGMA) has been shown to possess attractive biological and thermoresponsive properties, serving as an alternative to both poly(ethylene glycol) (PEG) and poly(N-isopropylacrylamide) (PNIPAM) depending on the number of ethylene oxide repeat units in the POEGMA side chain. Our group has shown the versatility of POEGMA and has successfully developed hydrazide- and aldehyde-functionalized polymer precursors that form an injectable in situ gelling hydrogel. By engineering the precursor polymer structure and crosslinking density (i.e. number of reactive functional groups in the precursor polymers), the properties of these hydrogels can be tuned. Herein, a hyperbranched structure was incorporated into POEGMA precursors to control the physical and biological properties of hydrogels independent of the chemistry while maintaining gel injectability. By varying the degree of branching (DoB) in these precursors, it was possible to tune the hydrogel properties based on reacting combinations of hyperbranched-linear and hyperbranched-hyperbranched precursor polymers. While it was feasible to tune the mechanical properties of the hyperbranched hydrogels based on the DoB, the hyperbranched-hyperbranched system showed diminished mechanical strength when compared to the hyperbranched-linear system. Overall, the mechanical properties of the whole hydrogel series were comparable to previously reported linear POEGMA hydrogels. In terms of swelling and degradation kinetics, the swelling and degradation rate in both acid-catalyzed conditions and in phosphate-buffered saline (PBS) at physiological temperature (37°C) correlated with DoB and polymer size. The precursor polymers showed minimal cytotoxicity in the presence of 3T3 mouse fibroblasts. Lastly, each of the hyperbranched hydrogels adsorbed higher quantities of protein compared to PEG-based hydrogels, but still relatively low amounts compared to other polymeric biomaterials. We have shown that it is possible to significantly tune the physicochemical properties by slightly changing the polymer precursor chemistry, namely by varying the amount of crosslinker and, thus, the degree of branching in the polymer network. Therefore, hyperbranched POEGMA offers a versatile platform to create tunable hydrogels based on polymer precursor structure for biomedical applications.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Lateral Loading of Small-Scale Shear Wall Buildings with Floor Slabs

contributor:
Heidebrecht, A. C.
Civil Engineering

subject: lateral loading, small-scale, shear wall, buildings, floor slabs

abstract:
 This thesis describes the construction and testing of small-scale shear wall buildings with rigidly connected floor slabs, but without wall openings. A micro-concrete material was used in the casting of both the basic small-scale shear wall buildings and the floor slabs. The vertically cantilevered buildings were tested by applying a transverse static load at the top of the buildings.

 The behaviour of buildings with only floor slabs was compared with that of buildings containing only wall openings. The results of static loading of the buildings were compared with those results predicted analytically using Vlasov's thin-walled elastic beam theory.

abstract: Thesis

abstract: Master of Engineering (MEngr)