title: The Soviet Constitution, 1917-1953, Some General Aspects

subject: Soviet, Soviet constitution, soviet constitution 1917-1953, 1917-1953

abstract: In this thesis I have attempted to give some indication of the divergence of the theory underlying the Soviet Constitution from the principles of classical Marxism. The scope of this subject is such that each facet with which I have dealt merits further extensive study and analysis, although I would humbly submit that such further consideration would serve only to verify, substantially. the main conclusions which I have reached. The subject of the thesis is dynamic. The period with which I have dealt is too recent and too momentous to permit complete objectivity to be achieved, and I can only express the hope that my dislike of the arbitrary use of power has been tempered by my enthusiasm for economic, social and political experiment based on profound humanitarian motives. The bibliography omits my most important acknowledge, and I therefore take this opportunity of thanking Mr. D. Novak for his invaluable advice and assistance.

abstract: Thesis

abstract: Master of Arts (MA)


title: Little Bugs and the Great Coral Crunching Sponge

subject:
coral crunching sponge
little bugs

abstract:
A 4.6-fold increase in the bimass of Cliona delitrix infesting Montastrea cavernosa substrate occurred in a portion of the Grand Cayman fringing reef affected by the discharge of untreated fecal sewage.It is suggested that the 6.3-fold increase in bacteria biomass (both coliforms and natural marine bacterioplankton) is linked to the sponge proliferation at the polluted site.
Since demosponges normally obtain much of their nutritional needs from URPOC and only 11 from bacteria, the significance of the elevated bacteria count may be limited to its importance as a flag as an indicator of untreated sewage effluent.
At the polluted study site, Montastrea cavernosa exhibited a 451 reduction in the amount of substrate occupied by living polyps.The loss of this respiring coral biomass is probably not compensated for by the biomass increases of C. delitrix and of the microflora inhabiting the dead substrate.The increased C. delitrix biomass reflects a. similar increase in the amount of M. cavernosa skeleton that has been eroded and reduced to silt-sized sediment. Thus, the discharge of untreated sewage into the reef environment can have a profound effect upon the trophic distribution of reef fauna, leading to a disturbance of the precarious balance between carbonate production and destruction on the reef.

abstract: Thesis

abstract: Bachelor of Science (BSc)


title: Phenotypic Analysis of Platelets in Patients with Platelet Function Disorders

contributor:
Hayward, Catherine
Medical Sciences

abstract: Many rare and severe forms of platelet function disorders (PFD) are now well characterized, however, information is only emerging about the phenotype and causes of many common types of PFD. This thesis aimed to extend the knowledge on uncharacterized PFD that manifest with impaired platelet aggregation function with multiple agonists, and/or platelet dense granule (DG) deficiency (DGD) by addressing some unanswered questions about laboratory findings for these PFD and whether some PFD have defects in platelet procoagulant function in assays using platelet rich plasma. First, we assessed the test characteristics and diagnostic usefulness of testing for DGD by whole mount electron microscopy (EM). We found that this test has acceptable performance characteristics, with a within-subject coefficient of variation (CV) of 12% for samples with normal DG counts. Confirmed DGD by whole mount EM showed significant association with increased bleeding symptoms and the clinical diagnosis of a bleeding disorder (Odds Ratio: 97, 95% CI: 5.7-1700). Light transmission aggregometry, and DG adenosine triphosphate release (estimated by lumi-aggregometry), were not sufficiently sensitive for detecting DGD as their respective sensitivities for detecting platelet function abnormalities due to DGD were only ~52% and 70%. Next, we evaluated for aberrant persistence of platelet non-muscle myosin IIB (MYH10) in a cohort with PFD, including those caused by mutations in transcription factors, such as RUNX1. While some participants with RUNX1 mutations showed the expected abnormal MYH10 findings, one had consistently normal findings. In another family with a PFD of unknown cause that impaired aggregation with multiple agonists, MYH10 findings varied from normal to abnormal among the affecteds. Lastly, we evaluated platelet procoagulant function in PFD using thrombin generation assays, and found that platelet-dependent thrombin generation was normal in many PFD with impaired aggregation responses and/or DGD, with abnormalities detected in the subgroup with RUNX1 mutations. Platelet-dependent thrombin generation was also impaired in Quebec platelet disorder (QPD). Unlike the other PFD subjects studied, QPD participants had platelet Factor V (FV) deficiency. In QPD, but not other participants, platelet FV showed a significant association to endogenous thrombin potential (R2=0.81) and peak thrombin concentration endpoints (R2=0.88) for PRP samples, suggesting platelet FV is important for thrombin generation. The findings from this thesis help clarify the phenotypic abnormalities associated with PFD, with implications for diagnostic testing. The studies also illustrated that the functional defects in some PFD extend to the ability of platelets to support thrombin generation.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: Platelets are blood cells that are important to limit bleeding as they stick at sites of injury and help blood to clot. The medical term for conditions where platelets don’t function properly is platelet function disorders (PFD). Laboratory tests are important to diagnose PFD. We evaluated our experiences with some tests for diagnosing PFD, including whole mount electron microscopy (EM), a test that looks for a type of PFD called platelet dense granule deficiency. We also evaluated other diagnostic tests, including a test for a platelet protein called MYH10. We also evaluated how platelets support blood clotting - an aspect of platelet function that hasn’t been tested much in PFD. We found that whole mount EM is helpful to diagnose PFD, unlike tests for MYH10. We also found defects in how platelets support blood clotting in some but not all types of PFD. The findings help clarify what tests are useful to assess PFD.


title: Design and Characterization of a Miniaturized Fluorescence Analysis System for Measurement of Cell-Free DNA

contributor:
Selvaganapathy, Ravi
Biomedical Engineering

subject:
Miniaturized Fluorescence System
Cell-Free-DNA
Sepsis Quantification

abstract:
Sepsis is a dysregulated systemic response to infection and is one of the leading causes of in-hospital mortality in Canada. Accurate distinction between survivors and non-survivors of sepsis has recently been demonstrated through quantification of cell-free DNA (cfDNA) concentration in blood. In an analysis of 80 septic patients, non-survivors of sepsis had significantly higher cfDNA concentration levels than that of survivors or healthy patients. Real time separation of cfDNA from contaminants in blood has also been done using a cross channel microfluidic device. Current methods for DNA quantification utilize time consuming and complicated laboratory equipment and therefore are not suitable for bedside real-time testing. Thus a handheld cfDNA fluorescence device coined the Sepsis Check was designed that can perform DNA characterization in a reservoir device and DNA detection in a microfluidic cross channel device. The goal is to use this system along with the cross channel devices to set apart survivors or healthy donors from non-survivors in patients with sepsis.
The design consists of a 470𝑛𝑚 light emitting diode (LED) with 170𝑚𝑊 of optical power (LED470L – ThorLabs), an aspherical uncoated lens with a focal length of 15𝑚𝑚 (LA1540-ML – ThorLabs), a 488𝑛𝑚 bandpass filter with a 3𝑛𝑚 full width at half maximum (FWHM) (FL05488-3 – ThorLabs), an aspherical uncoated lens with a focal length of 25𝑚𝑚 (LA1560-ML – ThorLabs), an aspherical uncoated lens with a focal length of 35𝑚𝑚 (LA1027-ML – ThorLabs), a 525𝑛𝑚 longpass filter with an optical density >4.0 (F84744 – Edmund Optics), and a Raspberry Pi Camera V2 (Raspberry Pi Foundation). The Sepsis Check is made to excite the dsDNA specific PicoGreen fluorophore which has a peak absorbance at 502𝑛𝑚 and a peak emission at 523𝑛𝑚. In summary, the Sepsis Check in this thesis is capable of calibrating dsDNA concentration from 1𝜇𝑔/𝑚𝐿 to 10𝜇𝑔/𝑚𝐿 and detect DNA accumulation of 5𝜇𝑔/𝑚𝐿 and 10𝜇𝑔/𝑚𝐿 in the cross channel device. This tool can be a valuable addition to the ICU to rapidly assess the severity of sepsis for informed decision making.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: DEVELOPING LIPOSOMES FOR ANTIBIOTIC ENCAPSULATION

contributor:
Hosseini-Doust, Zeinab
Chemical Engineering

subject: Liposomes antibiotics nanoparticles

abstract: Liposomes are self-assembled lipid vesicles made from phospholipids that are safe and suitable for drug encapsulation and localized drug delivery. Liposomal formulations are characterized by low toxicity and improved therapeutic index (by changing drug biodistribution) and liposomes encapsulating antifungal or anticancer drugs have already been approvedby regulatory agencies.One area of application for liposomes is localized antibiotic delivery. Antibiotics target bacteria, but specific types of infections(namely biofilms or intracellular infections)that required high or prolonged antibiotic administration have long been a challenge for antibiotic treatments. Liposomal delivery of antibiotics can improve their therapeutic index while minimizing their adverse effects. When it comes to methods of antibiotic encapsulation, however,most reports to date follow the methods developed for anticancer drugs for encapsulating antibiotics. This oversight causes discrepancies in the literature, mainly because of the significantly different chemical structures of antibiotics and cancer drugs. Furthermore, most antibiotics are highly sensitive to temperature fluctuations, which is concerning, given most liposomal preparation methods involve extreme temperature fluctuations. The aim of my thesis was to explore these missing links in the literature by answering these questions: (1) will liposome preparation method affect encapsulation efficiency of antibiotics?And (2) does liposomal preparation method adversely affect the efficacy of antibiotics?Investigating these questions led to further insight into the optimal process for achieving high encapsulation efficiencies for different antibiotics and for further avoiding damage due to harsh processing conditions. We found that different preparation methods are better for different types of antibiotics, being the one that promotes a large aqueous space better for hydrophilic drugs and the one that creates oligolamellar and large unilamellar vesicles better for more hydrophobic drugs. The steps in liposome preparation methods such as heating and sonication can affect the stability of the antibiotics.

abstract: Thesis

abstract: Master of Applied Science (MASc)

abstract: When antibiotics are administered, orally or intravenously, they should pass through different tissues to arrive to the site of infection; this can cause dilution and/or intoxication. To overcome these problems, drug delivery vehicles have been used to encapsulate and deliver antibiotics, improving their therapeutic index while minimizing their adverse effects. Liposomes are vesicles composed of at least one lipid bilayer, with an inner aqueous compartment. Liposomes are an attractive vehicle to deliver antibiotics because they can encapsulate both hydrophobic and hydrophilic antibiotics, they have low toxicity, and they can change the bio-distribution of the drug. In mythesis, I addressedtwo main questions regarding liposomal antibiotic encapsulation:(1) will liposome preparation method affect encapsulation efficiency of antibiotics, and(2) does liposome preparation method adversely affect the efficacy of antibiotics. While investigating these questions,I also identified certain outstanding biases in the liposomal characterization methods.


title: Nonlinear Phase Noise in Dispersion Unmanaged Fiber-Optic Systems

contributor:
Kumar, Shiva
Electrical and Computer Engineering

subject:
Fiber Optic Communications
Nonlinear Phase Noise
Self-Phase Modulation

abstract:
Since the introduction of optical fibers in 1960's in communication systems, researchers have encountered many challenges to improve the signal quality at the receiver as well as transmitting the signal as distant as possible. The former was achieved by employing coherent receivers, which let us use M-array modulation formats, such as QPSK, or QAM, and polarization of the signal. The later is accomplished by the advent of optical amplifiers. Optical amplifiers  enable us to compensate for the loss occurred within the fiber optic line, without the need for optical-electrical signal conversion. These amplifiers add noise to the line which interacts with the nonlinearity in the fiber line. This interaction causes phase change in the propagating signal called nonlinear phase noise, which degrades the system performance.

In this study we will derive an analytical expression for the linear and nonlinear phase noise variance in dispersion unmanaged fiber optic systems, using a first-order perturbation theory. We use numerical examples to depict the proposed system performance in terms of nonlinear phase noise variance. We will conclude that the nonlinear phase variance in a dispersion unmanaged system is much lower than the corresponding noise variance in a dispersion managed system. We will use this concept and will introduce more dispersion in the line by adding fiber brag gratings (FBGs) throughout the fiber link. Through numerical simulations, we will illustrate the improvement we get by adding FBG in each span. We will show that employing FBG improves the system performance for systems working at symbol rates 5 GBaud, which we get the best improvement to less than 20 GBaud, and beyond 20 GBaud there will be no improvement.

Nowadays, telecommunication systems based on fiber optics are working at symbol rates around 28 GBaud. We will introduce new models to reduce the nonlinear phase, by splitting digital back propagation (DBP) between transmitter and receiver, and using optical phase conjugation (OPC) in the line. We will prove that the new proposed models lower the phase noise variance significantly, for single pulses. We will also illustrate numerical examples to validate the betterment they provide in terms of Q-factor.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Anomalies of the Absorption Curve of Cosmic Rays in Lead

title: The Absorption of Cosmic Rays

contributor:
Gulbis, Fricis
Physics

subject:
anomaly
absorption curve
cosmic rays
lead

abstract: This thesis contains a brief description of the apparatus, the procedure, and the results of an investigation of the absorption of cosmic rays in thin absorbers. The existence of an anomalous maximum at a thickness of 10.5 cm. of lead is reported, which is tenatively interpreted as being caused by the production of a penetrating ionizing radiation by a neutral radiation through some seemingly unknown process.

abstract: Thesis

abstract: Master of Science (MS)


title: The Capture Cross-Sections of Neodymium Isotopes for Pile Neutrons

title: Neutron Capture by Neodymium Isotopes

contributor:
Thode, H. G.
Physics

subject:
cross-section
neodymium isotope
pile neutron

abstract: A Dempster-type double-focussing mass spectrometer has been used to determine the relative abundances of the isotopes of neodymium using two samples, one irradiated in a strong neutron flux, the other, obtained from the same source, unirradiated. A comparison of these results permits the calculation of the cross-section of each isotope for the capture of pile neutrons. Results previously obtained have been extended to give definite cross-sections for three of the isotopes, two of which have not previously been reported, and to lower the upper limits for the remainder.

abstract: Thesis

abstract: Master of Science (MS)


title: A Report of a Solid Source Dempster Type Double Focusing Mass Spectrometer

subject:
Dempster
double focusing mass spectrometer
mass spectrometer
solid source dempster

abstract: A description of a Dempster type double focusing mass spectrograph, converted to a mass spectrometer is reported. The latter part of the thesis deals with an investigation of a Shaw type solid ion source. Ten microgram samples of VaCl2 and SrCl2 yielded measurable ion currents of 1.0 x 10-11 amperes. Results with UF4 and PbI2 are also reported.

abstract: Thesis

abstract: Master of Science (MS)


title: NOVEL HEAT TREATMENT APPLICATIONS FOR CONCENTRICALLY BRACED FRAMES

contributor:
Becker, Tracy
Civil Engineering

subject:
Gusset plate
Brace
Steel heat treatment
Capacity design
High strength steel

abstract:
Concentrically braced frames (CBFs) have been widely used in seismic areas as efficient structural systems to provide both lateral stiffness and strength. They dissipate earthquake energy through the inelastic deformation of the braces in both tension and compression. While these frames are efficient in providing lateral stiffness and strength, their inelastic mechanism is not ductile when compared to other systems such as moment resisting frames (MRFs). This student proposes a new approach to enhance the ductile behavior of CBFs by locally heat treating gusset plate connections or braces. In this method, the steel is heated locally to austenitizing temperature and then cooled with the appropriate rate to achieve the desired material properties.
In gusset plate connections, to permit the rotation imposed from brace buckling, the conventional approach is to use linear fold lines, which can result in overly large plates. A more compact design uses elliptical fold lines, but both designs can lead to damage to welds with surrounding components. To enhance the performance of the gusset plate connection, a yield path is defined with a locally weakened zone within a high strength steel gusset plate. The weakened zone, created through heat treatment concentrated the inelastic deformation, resulting in an efficiently sized connection in which the failure mechanism is tightly controlled. A design methodology for the heat treated gusset plate is proposed, and finite element analysis is used to analyze the behavior of the heat treated gusset plates.
In conventional braces, repeated buckling leads to deterioration and low-cycle fatigue which limits the ductility capacity of the CBF, compared to MRFs. As a novel approach, heat treatment is used to increase the local yield strength in the brace. Through this method, the buckling is permitted to occur, but an enhancement in the buckling behavior is intended. Various heat treated configurations are investigated, and finite element analysis is used to compare the behavior of heat treated braces.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Effect of Pressure and Temperature on Lattice Parameters of Nepheline

contributor:
Burley, B.J.
Geology

subject:
pressure
temperature
lattice parameters

abstract: An experimental investigation was made involving the synthesis of nepheline (NaAlSiO4) under varying conditions of temperature and water pressure 2022-2130 for each synthesized charge was obtained using x-ray diffraction methods. It was found that the results of the individual runs provided an erratic lattice parameter variation with temperature in the range 500 to 800 degrees Celsius. However, a least squares curve indicates that no change in lattice parameters in the low-nepheline polymorph occurs with temperature of formation, for 95 percent probability.

abstract: Thesis

abstract: Master of Science (MS)


title: Generic Model-Agnostic Convolutional Neural Networks for Single Image Dehazing

contributor:
Chen, Jun
Electrical and Computer Engineering

subject:
image dehazing
deep learning

abstract: Haze and smog are among the most common environmental factors impacting image quality and, therefore, image analysis. In this paper, I propose an end-to-end generative method for single image dehazing problem. It is based on fully convolutional network and effective network structures to recognize haze structure in input images and restore clear, haze-free ones. The proposed method is agnostic in the sense that it does not explore the atmosphere scattering model, it makes use of convolutional networks advantage in feature extraction and transfer instead. Somewhat surprisingly, it achieves superior performance relative to all existing state-of-the-art methods for image dehazing even on SOTS outdoor images, which are synthesized using the atmosphere scattering model. In order to improve its weakness in indoor hazy images and enhance the dehazed image's visual quality, a lightweight parallel network is put forward. It employs a different convolution strategy that extracts features with larger reception field to generate a complementary image. With the help of a parallel stream, the fusion of the two outputs performs better in PSNR and SSIM than other methods.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: A Field Emission Ion Source

contributor:
Thode, H.G.
Physics

subject:
field emission
ion source

abstract: The construction of a field emission ion source and its adaptation to a mass spectrometer is described. The problems involved and the advantages of such an ion source are discussed.

abstract: Thesis

abstract: Master of Science (MS)


title: Studies on the Chemistry of Annotinine

contributor:
MacLean, David B.
Chemistry

subject: chemistry annotinine

abstract: The amino acid C14H19O4N, obtained from annotinine by oxidative fission of ring A, has been converted to the o,N-diacetyl acyclic anhydride C18H22O6N, and the anhydride ring has been shown to be five-membered. Oxidation studies have been carried out on the N-methyl lactone C17H27O2N, obtained by fission of ring A, and the oxidation products isolated and characterized. Hofmann degradation studies on the N-methyl lactone have been carried out and the products isolated from this reaction are discussed in relation to the known structure of the alkaloid.

abstract: Thesis

abstract: Master of Science (MS)


title: Establishing novel biomaterial applications of poly(ethylene glycol) based on its ability to bind water and control its environment

contributor:
Sheardown, Heather
Chemical Engineering

subject:
poly(etheylene glycol)
biomedical
drug delivery
polymers
silicone hydrogel
biocompatibility

abstract:
Polymeric biomaterials have created significant advances in the field of biomedical engineering, however, very few polymeric drug delivery devices have achieved clinical and commercial success. Thus, the motivation for this thesis was to encourage long-term success of materials through expanding the fundamental understanding of polymer properties.
Poly(ethylene glycol) was specifically chosen for study as its polyether backbone provides it with many unique properties that are still not fully understood, and are not seen with other similar polymers. PEG has been shown to exhibit amphiphilic character, due to its high conformational freedom, and the ability to hydrogen-bond 2-3 water molecules for each ethylene oxide subunit, creating a very structured water shell and large hydrodynamic radius. Together, the properties formed the hypothesis for the possibility for PEG to control drug release and its environment, expanding its potential in biomedical applications.
This hypothesis was investigated with PEG in three states – free PEG, conjugated and blended. Free PEG was determined to inhibit melanoma cell viability by activating apoptosis via PEG effects on the osmolality of the cell medium (Chapter 3). Novel silicone hydrogels incorporating methacrylated PEG  as the sole hydrophilic component showed advantageous properties for biomedical applications across a range of formulations (such as low contact angle and protein deposition), as well as altering the release of highly hydrophilic antibiotics from the materials, presumably via PEG-drug hydrogen bonding (Chapter 4). Novel siloxane-PEG blended materials were shown to have the ability to influence drug release of hydrophilic, hydrophobic and drug salts through the structure of PEG (Chapter 5).
Overall, the work within this thesis expanded understanding of the abilities and limitations of PEG based on its distinct structure, and expanded the potential for PEG in biomedical applications to more than being used as simply a hydrophilic additive.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract:
Polymeric biomaterials have created significant advances in the field of biomedical engineering, however, very few polymeric drug delivery devices have achieved clinical and commercial success. Thus, the motivation for this thesis was to encourage long-term success of materials through expanding the fundamental understanding of polymer properties.
Poly(ethylene glycol) was specifically chosen for study due to its unique exhibition of amphiphilic character and the ability to hydrogen-bond multiple water molecules, that together suggest the possibility for PEG to control drug release and its environment.
Through strategic experimental designs, greater understanding of the abilities and limitations of PEG was established and shown to be the result of the distinct structure of PEG.  Specifically, two novel drug delivery systems were developed with demonstrated understanding of the structure-function relationship between polymers and drugs, and the activity of PEG as a melanoma cell viability inhibitor was discovered and found correlated to the PEG structure. Overall the work within this thesis expanded the potential for PEG in biomedical applications to more than being used as simply a hydrophilic additive.


title: DEVELOPING HYDROGELS WITH SELF-ORGANIZED M13 FILAMENTOUS PHAGE

subject: Hydrogels, M13 phage

abstract:
Bacteriophages (phages) are bacterial viruses. Phages offer remarkable diversity and can be found in many shapes and sizes; however, what they all have in common is that they are made of protein nano-shells that encase their genome (DNA or RNA). In other words, phages are proteinous bionanoparticles. In this work, we use the filamentous phage M13. M13 is a simple virus with a high aspect ratio. It has 11 genes and only 5 structural proteins. The phage filament is almost entirely made of 2700 copies of pVIII, the major coat protein, and is capped off on one end by five copies each of the proteins pIII and pVI, while the opposite end displays five copies each of the proteins pVII and pIX. M13 phage can be genetically engineered to display certain peptides with affinity toward cancer cells, specific tissue, or even minerals and polymers. These filaments can further self-organize to form liquid crystals at high concentrations. All these properties make M13 a unique building block for the bottom up synthesis of advanced bioactive material.
The objective of my proposed research is to develop hydrogels using M13 phage. Hydrogels can absorb large quantities of water without dissolving. They mark a breakthrough in the field of biomaterials, owing to their high water content, porosity and soft consistency. I crosslinked M13 at liquid crystalline concentrations using glutaraldehyde. The resulting hydrogels were characterized for swelling and mechanical properties. These hydrogels exhibited self-healing and autofluorescence properties. In addition, I demonstrated that M13 can from self-healing hydrogels at lower concentrations by adding the small globular protein, BSA.
The developed M13 hydrogels mark the first step in the development of bioactive hydrogels that could be utilized to direct cell destiny and genuinely mimic the natural tissue.

abstract: Thesis

abstract: Master of Applied Science (MASc)

abstract: Filamentous phage are viruses that infect bacteria. These bio-filaments are ~1 𝜇𝑚 long, 6-8 nm in diameter and can propagate themselves by infecting bacteria. This means one bio-filament can make 300-1000 particles only by infecting a bacterial host, a characteristic that drastically increases their utility over synthetic filamentous nanomaterial. Filamentous phage can be readily genetically engineered to express foreign receptors on their surface. In this thesis, I demonstrate how these bio-filaments can self-organize at high concentrations and can be crosslinked to make hydrogels that can adsorb up to 12 times their weight in water. These hydrogels can also heal themselves if broken or cut and exhibit autofluorescence, which are very useful properties for hydrogels used for biomedical applications. We further demonstrate that adding small proteins to the bio-filaments can expand the range of hydrogel formation, to the extent that even low concentrations of bio-filament can form hydrogels.


title: Relatively Maximal Covering Spaces

contributor:
Banaschewski, B.
Mathematics

subject: maximal covering spaces, math, relatively maximal covering spaces, covering spaces

abstract: This thesis deals with the existence and properties of certain types of covering spaces. It contains the discussion of a generalization of the notion of simple connectedness and several well-known theorems depending on this.

abstract: Thesis

abstract: Master of Science (MS)


title: An Investigation of the Separation and Activity of Nuclear and Mitochondrial Fractions of Plant Tissue

subject:
plant tissue
nuclear fractions
mitochondrial fractions

abstract:
Thesis
Master of Science (MS)


title: The Effect of Certain Environmental Factors on Ascospore Formation in Saccharomyces Cerevisiae (Meyen) Reess

title: Ascospore Formation in Saccharomyces

subject: ascospore formation, saccharomyces, environmental facors on ascospore formation, saccharomyces cerevisiae, saccharomyces cerevisiae meyen reess

abstract: Certain problems relating to the formation of ascospores by baker's yeast were investigated. The effect of acetate concentration and cell population density on ascospore formation and optima were determined. An effort was made to determine factors responsible for some unpredictable variation in ascospore abundance. Certain chemicals were evaluated as sporulation stimulants with results that may be of value in yeast taxonomy. The effect of adding sporulation stimulants to both presporulation and sporulation media was also studied.

abstract: Thesis

abstract: Bachelor of Arts (BA)


title: The Structure of the Carbonyl Ring of Lycopodine

contributor:
Maclean, D.B.
Chemistry and Chemical Biology

subject: carbonyl ring, carbonyl ring of lycopodine, lycopodine, structure of the carbonyl ring, carbonyl ring structure, carbonyl ring of lycopodine

abstract: The structure of lycopodine was investigated in the neighbourhood of the carbonyl group. The results obtained enabled the elucidation of a large part of the peripheral structure of the alkaloid.

abstract: Thesis

abstract: Master of Science (MS)


title: A Scintillation Counter For Use in Medical Research and the Stopping of Mesons in Absorbers at Low Altitudes

contributor:
Johns, M.W.
Gulbis, Fricis
Science

subject: scintillation, scintillation counter, scintillation counter for use in medical research, stopping of mesons, mesons in absorbers, mesons in absorbers at low altitudes

abstract: This thesis is made up of two parts. Part A - describes the construction of a scintillation counter and its operation, as an instrument for use in medical research. Part B - is a study of the stopping of mesons in various absorbers as a preliminary to the investigation of the meson decay process.

abstract: Thesis

abstract: Master of Science (MS)


title: Dinucleotide Junction Cleavage Versatility of 8-17 Deoxyribozyme

contributor:
Li, Yingfu
Biochemistry

subject:
8-17 deoxyribozyme
dinucleotide junction

abstract: We conducted 16 parallel in vitro selection experiments to isolate catalytic DNAs from a common DNA library for the cleavage of all 16 possible dinucleotide junctions of RNA incorporated into a common DNA/RNA chimeric substrate sequence. We discovered hundreds of sequence variations of the 8-17 deoxyribozyme - an RNA-cleaving catalytic DNA motif previously reported - from nearly all 16 final pools. Sequence analyses identified four absolutely conserved nucleotides in 8-17. Five representative 8-17 variants were tested for substrate cleavage in trans and together they were able to cleave 14 dinucleotide junctions. New 8-17 variants required Mn2+ to support their broad dinucleotide cleavage capabilities. We hypothesize that 8-17 has a tertiary structure composed of an enzymatic core executing catalysis and a structural facilitator providing structural fine-tuning when different dinucleotide junctions are given as cleavage sites.

abstract: Thesis

abstract: Master of Science (MSc)


title: The Relationship Between Religious Affiliation and Secular Attitudes and Behaviour

contributor:
Jones, Frank E.
Sociology

subject:
religious affiliation
Catholic
Anglican
Protestant
secular attitude
behaviour
politics
economics
leisure

abstract: Consideration is given in this thesis to the relationship of religious affiliation of Catholics, Anglicans and Other Major Protestant denominations, to secular attitudes and reported behavior. The latter is analyzed in terms of the political, as manifested in voting preferences, and the economic, as illustrated by attitudes toward work and reported behavior in leisure periods. Leisure time activity was examined in the areas of reading, hobbies and visiting of friends and relatives. The data used in this study was obtained from The McMaster Study of Life in the City conducted in the North End of the City of Hamilton, Ontario in the summer of 1962.

abstract: Thesis

abstract: Master of Arts (MA)


title: Student Political Attitudes at McMaster University

contributor:
Kersell, J.E.
Political Economy

subject:
politics
political attitudes
survey
McMaster University
undergraduate
party preferences
ideological attitudes
family background
academic background
socioeconomic status
religion

abstract:
This thesis is a report of a survey of a political attitudes at McMaster University. The results are based on the data obtained in interviews with 193 undergraduates chosen in a random sample of the undergraduate population. This information was used to examine the level of interest in politics among the members of the sample, and the different ideological attitudes and party preferences of the students interviewed.
The different levels of interest in politics were related to ecological factors such as family and school background, socio-economic status, sex, group involvement and place of residence. Political preferences were related to such factors as socio-economic status, religion, family preferences and academic interests.
The more interesting conclusions might be summarized as follows. The students as a whole are more apathetic towards politics than might have been expected. Those who have an above average interest in politics tend to be found among those studying Arts subjects at Honours level and whose parents also have an above average interest. They also tend to be male.
Students also tend to agree with their parents’ politics, except those who have a high level of interest in the subject.
Finally, the interested students tend to be more radical (at least by the scale set up for this survey) than the apathetic.

abstract: Thesis

abstract: Master of Arts (MA)


title: Brant Township

contributor:
Wood, H.A.
Geography

subject:
aerial differentiation
Brant Township
regional geography
systematic geography
land utilization
land use
Walkerton

abstract:
This study was undertaken to present the aerial differentiation within Brant Township. To express these differences most clearly the Township has been studied on a regional basis. This includes a breakdown of the study area into small subdivisions and the relationships of the unit areas to each other to discover the structural and functional basis of the larger area.
It must be remembered that regional geography is sterile without the concepts and principles from systematic geography. Therefore systematic geography has been employed for an understanding of the aerial differences in each kind of phenomena and the relationships between them. Throughout the study, emphasis has been placed on the basic land utilization pattern of the Township.
The land utilization maps are the result of systematic observation on a field to field basis. The functional map of Walkerton in the back cover illustrates the land use contained within the town. This map also constitutes the results of field work.
The study is divided into six chapters. The first chapter is a general introduction to the location, size and the physical geography are discussed. Chapter three is a detailed account of the historical development of the Township. The present day agriculture is dealt within Chapter four while non-agricultural land use, which includes on urban study, is discussed in chapter five. Chapter six, containing the summary and conclusion, completes the thesis.

abstract: Thesis

abstract: Bachelor of Arts (BA)


title: Mechanisms of O2-Chemosensitivity in Adrenal Medullary Chromaffin Cells from the Developing Rat and Mouse

title: Mechanisms of O2-Chemosensitivity in Developing Chromaffin Cells

contributor:
Nurse, Colin A.
Biology

subject:
suprarenal gland
adrenal gland
mammal
chromaffin cells
catecholamines
hypoxia
patch clamp techniques
carbon fibre electrochemistry
hypoxic chemosensitivity
rat
mouse
embryo
neonatal
anoxia

abstract:
The mammalian adrenal gland (or suprarenal gland) is a small organ located on the superior aspect of the kidney. The central region of the gland, the medulla, consists of chromaffin cells, which release catecholamines into the blood during periods of stress. This is best known as the 'fight or flight' response and is regulated, in the adult animal, by neuronal signals from the cholinergic sympathetic fibres of the splanchnic nerve. Interestingly, in some mammals, such as rat and human, sympathetic innervation is immature at birth, yet the chromaffin cells can still secrete catecholamines in response to physiological stessors, e.g. hypoxia. Increased plasma catecholamines is thought to provide a vital protective role for the neonatal animal during, and following birth. This is mediated in part by promoting lung fluid absorption, surfactant secretion, heart rate stabilization, and brown fat mobilization. The observation that, in the neonate, catecholamines are secreted in the absence of functional sympathetic innervation suggests that the chromaffin cells possess other mechanisms for directly 'sensing' a fall in blood O2 tension (hypoxia).
The primary goal of this thesis was to uncover the mechanisms of oxygen-sensing in developing chromaffin cells from the rat and mouse, using primary short-term cell cultures of chromaffin cells. The experimental approaches relied on patch clamp techniques to record ionic currents and membrane potential, carbon fibre electrochemistry to record catecholamine secretion from cell clusters, and fluorescent indicators to measure reactive oxygen species generation.
Hypoxic chemosensitivity was found in embryonic and neonatal, but not juvenile chromaffin cells from both the rat and mouse. Exposure to hypoxia or anoxia caused a reversible suppression of whole-cell current, which was comprised of the differential modulation of three K+ currents: (1) suppression of a large-conductance Ca2+-dependent K+ current; (2) suppression of a delayed rectifier K+ current; and (3) activation of an ATP-sensitive K+ current. Hypoxia also induced membrane depolarization that was not initiated by any of these three voltage-dependent K+ currents. Additionally, hypoxia broadened action potentials in chromaffin cells that showed spontaneous activity, and this was mediated by a prolongation of the time course of membrane repolarization. All of these factors likely contribute to catecholamine secretion by enhancing the influx of Ca2+ through depolarization-activated L-type Ca2+ channels.
Two sets of experiments were designed to identify the oxygen sensor in neonatal chromaffin cells. First, cells from transgenic mice, deficient in the gp91^phox component of the putative O2-sensor protein, NADPH oxidase, responded to hypoxia in the same way as wild type cell, indicating that NADPH oxidase is not primarily responsible for oxygen sensitivity in these cells. Second, inhibitors of the proximal electron transport chain (e.g. rotenone and antimycin A) mimicked and attenuated the hypoxic response, while inhibitors of the distal electron transport chain (cyanide) and uncouplers of oxidative phosphorylation (2,4-dinitrophenol) had no effect. Furthermore, reactive oxygen species production, primarily H2O2, decreased during exposure to hypoxia or inhibitors of the proximal electron transport chain, revealing a potential mitochondrial mechanism for 'sensing' of the hypoxic stimulus.
Reduced oxygen availability to the electron transport chain is proposed to cause a fall in cellular reactive oxygen species (ROS), principally H2O2. This fall in ROS signals closure of Ca2+-dependent and Ca2+-independent K+ channels, which causes broadening action potentials and increases Ca2+ influx. The latter is further enhanced by the hypoxia-induced membrane depolarization, which in turn increases the probability of cell firing. The rise in intracellular Ca2+ then acts as the signal for catecholamine release from the chromaffin cells.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: A Study on the Decomposition in Lake Bottom Sediments in the Ordovician and Post-Ordovician of Ontario

subject:
lake bottom sediment
decomposition
ordovician
post-ordovician
ontario

abstract:
Thesis
Master of Science (MS)


title: CONTROL OF SILVER AND SILICON MICROSTRUCTURE VIA LOW DOSE ION IMPLANTATION

contributor:
Bassim, Nabil
Materials Science and Engineering

subject:
Thin Films
Ion Implantation
Dewetting Prevention
Impurity Drag
Surface Free Energy Model

abstract:
Ag thin film dewetting upon high temperature annealing is a non-trivial problem for its application in the semiconductor industry as an ohmic contact metal. Thus, preventing Ag thin film from dewetting is of great importance. Typically, adhesion-promoting layers of chromium are deposited to prevent dewetting, but this deposition has its own process optimization parameters. In this thesis, we introduce an alternative, novel strategy for dewetting prevention via Si or In ion implantation. Electron microscopy including SEM, AFM and AES are conducted to characterize changes in film morphology after ion implantation. Thermodynamic simulation is established to better understand the mechanism of this anti-dewetting approach as well as to predict the performance of doped Ag thin films.

It is found that Ag films implanted by a trace amount of Si dopants remain intact after 24 h annealing at 530℃ rather than break down into isolated particles as pure Ag film did. Furthermore, Ag grains in doped samples are much smaller than that in non-doped samples and higher Si or In doses contribute to smaller grains, indicating that a retarding force against film grain growth is introduced by the implanting species. Fortunately, electrical conductivity and optical reflectivity of doped films change trivially, suggesting an insignificant influence of external species on the film performance. The retarding force suppressing film grain growth is demonstrated to be solute drag, which will introduce a size limit towards Ag grain growth. A grain growth model including the solute drag effect is established here to describe the grain growth process. Combining our thermodynamic simulation with our grain growth model in the presence of the solute drag effect, the critical grain diameter to initiate agglomeration of 100 nm thick Ag thin film is calculated to be 350 nm and the critical Si dose to prevent 100 nm thick Ag thin film from dewetting is predicted to be 2.0×1013 per cm2.

Finally, we successfully synthesize ultrathin Si thin films via ion implantation and pattern as-deposited Si films by implanting through a hard mask in order to identify some steps towards synthesizing 2-D silicon, or silicene. The as-achieved pattern has an identical shape as that of mask, suggesting Si atoms only diffuse within the implanting regions during thermal annealing. Even though only amorphous Si films are prepared at present, this novel strategy possesses potential to fabricated CMOS-compatible 2-D silicon films for semiconductor industry.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: An Examination of the Role of Sphingosine-1-Phosphate in High Density Lipoprotein Mediated Protection of Macrophages Against Apoptosis

title: Role of HDL and S1P in Macrophage Signaling

contributor: Medical Sciences (Blood and Cardiovascular)

subject: HDL S1P Lipids Atherosclerosis

abstract:
Prevention of macrophage apoptosis in advanced atherosclerotic lesions can help stop atherosclerosis progression to vulnerable plaques.  High density lipoprotein (HDL) can protect macrophages from apoptosis that has been induced by a variety of agents. We hypothesize that this is the consequence of the sphingolipid, sphingosine-1-phosphate (S1P), specifically carried by HDL, and transferred to S1P receptor 1 (S1P1) on the cells via the HDL receptor, scavenger receptor class B type 1 (SR-B1).
Apoptosis was induced in murine peritoneal macrophages from wild type and different knockout mice with, tunicamycin, thapsigargin, staurosporine, or UV irradiation. Apoptosis was measured by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) or with cleaved caspase-3 (CC3) staining. Treatment of cells with HDL or S1P protected them against apoptosis induced by a variety of stimuli. In contrast, pre-treatment of HDL with S1P lyase, which irreversibly cleaves S1P, eliminated the ability of HDL to protect macrophages. Inhibition of SR-B1’s lipid transport activity reduced HDL dependant protection against apoptosis. Furthermore, HDL dependent protection against apoptosis induced by tunicamycin was prevented when the S1P receptor S1P1 was knocked out. However, this protection was not prevented when apoptosis was induced by staurosporine.
These results suggest that the HDL mediated protection of macrophages against apoptosis is multi-faceted and one approach may involve SR-B1 mediated delivery of S1P from HDL to the S1P1. Understanding the mechanisms by which HDL elicits atheroprotective signalling in macrophages will provide insight into new targets for therapeutic intervention in atherosclerotic disease.

abstract: Thesis

abstract: Master of Science in Medical Sciences (MSMS)

abstract: Atherosclerosis, is a disease where in the artery walls thicken due to cholesterol build-up, is the major underlying cause for cardiovascular diseases, which is currently a leading cause of death in many populations. We believe that HDL, the “good” cholesterol and S1P, a small molecule carried by HDL, can help prevent the progress of atherosclerosis by preventing macrophages, cells that absorb the cholesterol, from dying. We attempt to prove this by providing S1P or HDL to macrophages that are made to undergo cell death. Results show that both HDL and S1P can protect cells against cell death induced by many factors. However, HDL can protect against certain cell death inducing stimuli without the need for S1P and more research is required to fully understand HDL’s protective role in atherosclerosis. Understanding how HDL elicits atheroprotective signalling in macrophages will help in finding new drugs and therapies to reduce atherosclerosis-based deaths across the world.


title: Mapping cAMP Signalling by Nuclear Magnetic Resonance Spectroscopy

contributor:
Melacini, Giuseppe
Biochemistry and Biomedical Sciences

subject:
cyclic AMP
cAMP
protein kinase A
guanine exchange factors
allosteric mechanism

abstract:
Cyclic AMP (cAMP) is a second messenger that translates extracellular signals into tightly regulated biological responses. The cAMP binding domain (CBD) is a conserved regulatory switch that binds to cAMP and allosterically controls multiple cellular functions. All CBDs share a common architecture comprised of α- and β-subdomains. cAMP binds to the phosphate binding cassette (PBC) nested within the β-subdomain. In mammals the main cAMP receptors are protein kinase A (PKA), guanine exchange factors (EPAC) and ion channel proteins, including both the hyperpolarization-activated cyclic nucleotide-dependent channels (HCN channels) and the cyclic nucleotide-gated channels (CNG channels). Impaired activities of these proteins are associated with diabetes, cardiovascular diseases, cancer and Alzheimer's disease. Therefore, these proteins represent promising therapeutical targets. However, the mechanism of their cAMP-dependent allosteric control is not completely understood. In the present thesis we have studied the allosteric mechanism of activation in PKA and EPAC using an NMR-based approach and we have proposed a model explaining how cAMP allosterically controls the activity of PKA and EPAC.
Binding of cAMP to the Regulatory (R) subunit of PKA facilitates the release of the Catalytic (C) subunit. According to our model, binding of cAMP triggers long range perturbations that propagate from the PBC to the R:C interface through both direct and indirect pathways. The indirect pathway involves two key relay sites located at the C-terminus of β2 (1163) and at the N-terminus of β3 (D170). D170 functions as an electrostatic switch that mediates the communication between the PBC and the helical subdomain, whereas 1163 controls the global unfolding. Hence, removal of cAMP uncouples the α- and β-subdomains by breaking the circuitry of cooperative interactions radiating from the PBC. The proposed model was further validated by the cAMP agonist Sp-cAMPS and the cAMP antagonist Rp-cAMPS. It was observed that Rp-cAMPS, in which the equatorial exocylic oxygen is replaced by sulphur, does not activate a necessary indirect allosteric pathway, while its diastereoisomer (Sp-cAMPS) with opposite phosphorus chirality behaves similarly to cAMP activating all allosteric pathways. Our data also showed that the cAMP-antagonist stabilizes a ternary inhibitory complex between the effector ligand and both the regulatory and the catalytic subunits of PKA. At this point it is still not understood how the proposed model of cAMP allostery is conserved in other cAMP binding proteins such as EPAC.
EPAC is a multidomain guanine nucleotide exchange factor specific for small GTP-binding proteins and is directly activated by cAMP. We have probed how cAMP docks into the EPAC1 CBD and how its signal allosterically propagates from the cAMP binding site to the helical subdomain, which mediates the inhibitory interactions between the regulatory and catalytic regions of EPAC. Our comparative NMR investigation of cAMP signalling in PKA and EPAC revealed key functionally significant differences between these two systems that will facilitate the design of EPAC-selective therapeutics.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


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

title: Dissemination of Heart Health Promotion

contributor:
Taylor, S.M.
Geography

subject: Ontario

subject: public health system

subject: heart health

subject: health promotion

subject: health dissemination

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

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Alexandrian and Antiochene Exegesis and the Gospel of John

contributor:
Widdicombe, Peter
Religious Studies

subject: early Christianity; Antioch; Alexandria; biblical exegesis

abstract:
In this thesis I argue, against much recent scholarship on early Christian exegesis, that the traditional distinction between the two exegetical schools of Alexandria and Antioch, the allegorists and the literalists respectively, ought to be maintained. Despite much overlap in terms of the school members’ training in grammar and rhetoric (one of the major arguments put forward by those who wish to do away with the two schools), a critical distinction lies in the ways the exegetes of the two early Christian centres used Scripture for the spiritual development of their audiences. This I demonstrate through a close analysis of the exegetical treatments of five passages from the Gospel of John by four authors, two Alexandrians, Origen and Cyril, and two Antiochenes, John Chrysostom and Theodore of Mopsuestia. I attend to my authors’ use of a shared exegetical principle that
Scripture is inherently “beneficial” or “useful,” and therefore it is the exegete’s duty to draw out Scripture’s benefits, whether from the literal narrative or by moving beyond the letter to the non-literal plane. Examination of this principle allows us to understand these authors’ rationale—namely, the spiritual development of their audiences—for providing either a literal or a non-literal reading, rather than simplistically designating Alexandrians as “allegorists” and Antiochenes as “literalists.” I demonstrate that other than one brief instance, the Antiochenes remain at the literal level of the text to draw out Scripture’s benefits, whereas in every case the Alexandrians draw out benefit from the literal and the non-literal levels of the text. Moreover, I argue that one of the distinctive features of
Alexandrian exegesis was that one of the most important benefits provided by the biblical text was its direct application to these authors’ contemporary church settings, situations, and even to the individual Christian souls.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract:
In this thesis I seek to provide an answer to the question of whether there were two distinct schools of scriptural interpretation in the two major centres of Alexandria and Antioch in the church of late antiquity. Traditionally scholars have characterized the Alexandrian exegesis as allegorical or spiritual and Antiochene as historical or literal. In recent decades, scholars have sought to do away with the distinction, tending to focus on the school members’ shared training in rhetoric and grammar. I argue that the traditional distinction ought to be maintained, but I draw attention to a critical distinction between the two schools, namely, the ways in which the exegetes of the two centres apply
Scripture to their respective church settings. I demonstrate this by comparing the interpretations of five passages from the Gospel of John by two Alexandrian authors, Origen and Cyril, and two Antiochenes, John Chrysostom and Theodore of Mopsuestia.


title: On the Fluidic Forces and Shape Optimizations of Resonant Curved Cantilever Wings

contributor:
Kleiman, Rafael
Engineering Physics

subject:
Fluid Dynamics
MEMS
MAVS
RESONANCE
FLIGHT

abstract:
Artificial flight on millimeter size scales has been a major challenge due to the difficulty in making a feasible flight mechanism in terms of fabrication, thrust and power used. Many have tried to copy animal flight but there has been little success at such sizes. One proposed solution is to make small thrusters out of resonant curved cantilevers which act as wings that follow a simple 1 degree-of-freedom motion. Such wings are free of joint friction, can be planarly fabricated using well documented techniques, can be predictably scaled to different sizes, and have been shown to generate a net thrust.
In this thesis, the work investigates the nature of the wings’ thrust through thorough studies of computational fluid dynamic simulations to understand how they interact with the surrounding fluid and how exactly the forces are generated. Specifically, it considers the role of unsteady lagged fluid waves generated by the wings and explains how the wing-fluid interactions relate to drag coefficients at low to high flapping amplitudes and Reynolds numbers ranging from 100 - 100 000. It then studies the effect of different wing aspect ratios on the net force and power efficiencies. The results are then extended to a general dependence on the wings’ aspect ratio which allows for this parameter to be used in optimizing the wings’ net force/power used. Test wings are then made using an updated fabrication method and Molybdenum as the curve-inducing material in an attempt to produce more environmentally-stable wings with important successes, failures and improvements discussed. Results show that such Molybdenum-based wings are practical for flight, and that resonant curved cantilevers wings can be made more feasible by simple changes to their shape.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: OPTIMIZATION OF FACULTY DEVELOPMENT AT A DISTRIBUTED MEDICAL CAMPUS

contributor:
Vanstone, Meredith
Health Science Education

subject: distributed medical education, faculty devevlopment

abstract:
Background: Distributed Medical Education sites are satellites of large academic medical schools with faculty who are community-based physicians. These medical teachers need faculty development and there is little data about how this can best be delivered. This study asked the question: How can medical teaching expertise be developed and sustained at a Distributed Medical Education Campus? Using constructivist grounded theory methodology, a total of 16 semi-structured interviews were conducted with faculty members at two DME site campuses in Southern Ontario, and two faculty development events, one at each site, were observed.  Findings_ The communitWhat are the perceptions of faculty at a Distributed Medical Education site regarding effective and acceptable faculty development activities for improving their skills as medical educators? y in which a DME campus medical school is implanted is transformed through a process of interaction between learners, medical teachers, and the community itself, which results in the production of expert community teachers. Community based physicians can develop teaching expertise and require faculty development to maintain interest and skill. They can access high quality, relevant faculty development within their own practice groups, a model referred to as a Community of Practice. These communities can be virtual or in-person and need several elements to be successful, including facilitation and mentorship.
 Conclusion: Teaching experts can develop in a DME site when there is accessible, relevant faculty development, such as in a Community of Practice. More research is needed to determine the best way to reward community teachers, most of whom are part time faculty in private practice.

abstract: Thesis

abstract: Master of Health Sciences (MSc)

abstract: Recently, satellite campuses of medical schools have been established in smaller cities, called Distributed Medical Education (DME)  sites. There, the teaching faculty is composed of non-academic, community-based physicians. These faculty members need training to learn how to teach, or Faculty Development.  This study asked the question: How can medical teaching expertise be developed and sustained at a Distributed Medical Education Campus?   Sixteen interviews were conducted with teaching physicians, and two faculty development events were observed at two DME site campuses in Southern Ontario.  The findings of this study revealed that the community is transformed through a process of interaction between learners, medical teachers, and the community itself, resulting in the production of expert community teachers. These teachers can access high quality faculty development within their own practice groups, a model referred to as a Community of Practice.


title: Producing Medical Radioisotopes with CANDU Nuclear Reactors

contributor: Engineering Physics and Nuclear Engineering

subject: lutetium-177

subject: molybdenum-99

subject: radium-223

subject: lead-212

subject: bismuth-212

subject: Mo-99

subject: radioisotope

subject: CANDU

subject: DRAGON

subject: DONJON

subject: NJOY

abstract:
In the field of nuclear medicine, radioisotopes are used for applications such as diagnostic imag-
ing, treatment, and equipment sterilization. The most commonly used radioisotope in medicine is
technetium-99m (Tc-99m). It is used in 80% of all nuclear medicine procedures. Its parent isotope is
molybdenum-99 (Mo-99). NRU, which is now closed, formerly produced 40% of the worlds demand
for Mo-99. The production capacity of this reactor has been supplemented by a network of cyclotrons
and a modified research reactor. This study aims to provide an alternative means of production for
Mo-99, as well as other radioisotopes by modifying the center pin of a standard 37-element bundle of
a CANDU reactor.
The neutron transport code DRAGON, and the neutron diffusion code DONJON were used to
model a CANDU-9 reactor. The lowest, median, and highest power channels were chosen as candi-
dates for the modified bundles. It was found that the reactor parameters were altered by a negligible
amount when any one channel was used to house the modified bundles. Significant quantities of the
radioisotope lutetium-177 as well as the generating isotopes of the alpha-emitting radioisotopes lead-
212/bismuth-212, and radium-223 were produced. However, only minute amounts of molybdenum-99,
and the generating isotope of bismuth-213 were produced.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Evaluating Pressurized Gas Expanded Liquid Processed Carbohydrates for Biomedical and Bioseparations Applications

contributor:
Hoare, Todd
Chemical Engineering

abstract:
Significant challenges remain associated with forming scalable macroporous materials with high interconnectivity without requiring the use of substances that may cause negative effects in the end use of the material. In this light, pressurized gas expanded liquid (PGX) technology, a processing technique that uses ethanol and carbon dioxide to create high surface area morphologies in carbohydrate material, offers an attractive alternative. Through the chemical stabilization of these morphologies via crosslinking, the carbohydrate scaffolds can be used in multiple applications including the promotion of cell growth in tissue engineering applications, improvement in wound healing through moisture retention and delivery of biotherapeutics, and creation of interconnected internal morphologies in hard polymers for bioseparations and bone scaffolding applications by way of templating.
This thesis investigates these potential applications of PGX-processed materials. First, the effects of the morphology of PGX-processed chitosan crosslinked with varying amounts of genipin (which affect both the gel mechanics and the adhesiveness of the gel) are investigated on the proliferation and morphology of muscle cells. Second, highly interconnected alginate networks created through PGX-processing were impregnated with ibuprofen, ionically crosslinked and evaluated for their use as a burn wound dressing in vivo, with the gels demonstrated to maintain moisture and deliver an anti-inflammatory drug to suppress scarring during wound healing. Finally, alginate networks were used as sacrificial scaffolds in the creation of an interconnected internal morphology within a hard polymer shell for applications requiring both high interconnectivity and high mechanical integrity, such as bone scaffolding and bioseparations.
In conclusion, this work shows the promise of post-crosslinked PGX-processed carbohydrates in tissue engineering, wound healing and bioseparations.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: The Structure of Acrifoline

contributor:
MacLean, David
Chemistry

subject: structure chemistry acrifoline

abstract:
Thesis
Doctor of Philosophy (PhD)


title: The use of fluorescently labeled nanoparticles as therapeutic virus surrogates in sterile filtration studies

contributor:
Latulippe, David
Chemical Engineering

subject:
Nanoparticles
Surrogates
Microfiltration
Sterile filtration

abstract: Nanoparticles (NPs) have attracted considerable attention in the field of separation science, especially in filtration studies for direct membrane integrity tests, investigating pore-size distribution, and their potential to be used as surrogates for various types of viruses encountered in water treatment and bioprocessing applications. Although the effect of adding surfactants to stabilize NP suspension have been explored for a number of different applications, there is significant variation in the amounts and types of surfactants used in filtration studies. This study used three different sizes (59, 188, and 490 nm) of fluorescent polystyrene nanoparticles (PNPs) to mimic the length, width, and aggregates of Rhabdovirus Maraba, a bullet-shape envelope virus. The PNPs were suspended in solutions with varying concentrations of the nonionic surfactant Tween 20 (0.0005% to 0.1% (v/v) in the carbonate buffer feed solution) and were tested in constant-flux filtration studies using two commercial microfiltration (MF) membranes (Durapore PVDF and MiniSart PES) with 0.22 micron pore size ratings. Results clearly demonstrate that adding a nonionic surfactant to a PNP solution will cause a shift from full retention to complete transmission during the dead-end MF of PNPs that are smaller than the pore size of an MF membrane. In a separate study, in order to have a better resemblance of virus particles in terms of surface properties, 188 nm PNPs were coated with different (lysozyme, α -lactalbumin and bovine serum albumin) proteins in order to gain similar surface properties to actual virus particles. Filtration results with one type of commercial MF membranes (Durapore PVDF) 0.22 μm pore size, clearly indicate that the transmission behavior of PNPs strongly depends on their surface properties. PNPs fully covered with BSA and α–lactalbumin could completely pass through the membranes while uncovered or partially covered PNPs resulted in no transmission or partial transmission.

abstract: Thesis

abstract: Master of Applied Science (MASc)

abstract: Nanoparticles (NPs) has been employed enormously in various applications for a variety of purposes. One of the areas that have been greatly influenced by NPs, is the field of separation science. In the pharmaceutical industry, purification of therapeutics involves a sequence of filtration and in this step, therapeutic virus filtration, sterile filtration, in particular, have been poorly studied. There is also a growing interest in the use of engineered viruses for cancer treatment due to its magnificent implication on human health. However, there are significant challenges in running filtration experiments with pathogenic substances. Therefore it has been determined that a detailed and comprehensive study of sterile filtration of virus-size NPs can benefit this area. In this work, fluorescently-labeled NPs has been used as surrogates of oncolytic viruses to extract fundamental aspects affecting the transmission of virus-sized particles through commercial microfiltration sterilizing grade membranes.


title: Towards the creation of porous carbon materials from polysaccharide precursors: Feasibility of PGX processed polymers for the production of activated carbon

title: ACTIVATED CARBON FROM PGX POLYMERS

subject:
Activated Carbon
BET
Surface area
microporous

abstract:
This thesis investigates the feasibility of producing activated carbon from polysaccharides. Activated carbons are high surface area solids with rich surface functionality and as a result, find use in a variety of industrial separation processes. The market for activated carbon is already established and growing but there is a huge push to find sustainable alternatives for the raw material used for its production, which is primarily coal. While there exists a significant amount of research on agricultural residues as potential replacements, there is minimal information on using polysaccharides as precursors for the production of activated carbon.
Using the patented PGX process, two separate approaches were employed for the synthesis of activated carbon. The first method relied on the porous network of PGX materials to be maintained during pyrolysis while the second approach used a chemical agent to create porosity during the pyrolysis.
Gas sorption analysis revealed that the PGX structure was not maintained during the pyrolysis stage hence losing all its pore network and extended surface area. Additionally, no significant variation between the PGX and non PGX variants of the chemically activated polymers was observed.
However, it was revealed that the interaction between zinc chloride and pectin produced exceptionally high specific surface area (exceeding 2000 m2 g-1) activated carbon. The produced carbon had a high degree of microporosity (up to 100%) with some flexibility present in tuning the porosity. Elemental analysis revealed the carbon to have high
surface functionality and preliminary adsorption test for removal of heavy metal ions from water (Pb2+ and Cd2+) showed promising results with the in-house carbon performing better than a representative commercial carbon.
This study relies on statistical methods including multiple design of experiment studies and advanced characterization techniques to analyze the manufacturing process and the properties of carbon in an attempt to find the best conditions for producing activated carbon from polysaccharides.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: The Fractionation of Sulphur Isotopes in the Plant Metabolism of Sulfates

title: Fractionation of Sulphur Isotopes in Plant Metabolism

contributor:
Thode, H. G.
Chemistry

subject:
fractionation
sulphur
sulphur isotopes
plant
metabolism

abstract: The isotopic fractionation of sulphur in the plant metabolism of sulphate by chlorella was investigated; and for this purpose an apparatus was devised for growing chlorella under sterile conditions. A green alga from the shores of Lake Erie, and mustard plants from the field were also investigated. No isotopic fractionation was found in the plant metabolism of sulphate either in the laboratory or in nature. A new method for the reduction of sulphate to hydrogen sulphide was also developed.

abstract: Thesis

abstract: Master of Science (MS)


title: Incremental Fault Analysis: A New Differential Fault Attack on Block Ciphers

contributor:
Nicolici, Nicola
Electrical and Computer Engineering

subject:
side-channel
attack
fault
cryptography
hardware
security
AES
differential fault analysis
incremental fault analysis
DFA
IFA

abstract:
Electronic devices such as phones and computers use cryptography to achieve
information security. However, while cryptographic algorithms may be strong
theoretically, their physical implementations in hardware can leak unintentional
side information as a byproduct of performing their computations. A device's
security can be compromised from this leakage through side-channel attacks.
Research in hardware security reveals how dangerous these attacks can be and
provides security countermeasures. This thesis focuses on a category of
side-channel attacks called fault attacks, and contributes a new fault attack
method that can compromise a cryptographic device more rapidly than the previous
methods when using practical fault injection techniques.
We observe that as a circuit is further overclocked, new faults are often
superimposed upon previous ones. We analyze the incremental changes rather than
the total sum in order to extract more secret information.
Unlike many previous methods, ours does not require precise fault injection
techniques and requires no knowledge of when the internal state is in a specific
algorithmic stage. Results are confirmed experimentally on hardware
implementations of AES-128, 192, and 256.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Analytics Models for Corporate Social Responsibility in Global Supply Chains

contributor:
Hassini, Elkafi
Computational Engineering and Science

subject: Analytics models, corporate social responsibility, supplier selection and lot-sizing, predictive modeling, machine learning

abstract:
There have been several infamous incidences where world-renowned corporations have been caught by surprise when a low-tier downstream supplier has been publicly found to be non-compliant with basic corporate social responsibilities (CSR) codes. In such instances, the company reputation, and consequently financial health, suffer greatly. Motivated by the advances in predictive modeling, we present a predictive analytics model for detecting possible supplier deviations before they become a corporate liability. The model will be built based on publicly available data such as news and online content. We apply text mining and machine learning tools to design a corporate social responsibility "early warning system" on the upstream side of the supply chain. In our literature review we found that there is a lack of studies that focus on the social aspect of sustainability.
Our research will help fill this gap by providing performance measures that can be used to build prescriptive analytics models to help in the selection of suppliers. To this end, we use the output of the predictive model to create a supplier selection optimization model that takes into account CSR compliance in global supply chain context. We propose a heuristic to solve the problem and computationally study its effectiveness as well as the impact of introducing CSR on procurement costs as well as ordering and supplier selection patterns. Our models provide analytics tools to companies to detect supplier deviance behaviour and act upon it so as to contain its impact and possible disruptions that can shake the whole supply chain.

abstract: Thesis

abstract: Master of Science (MSc)


title: The Effect of Long-Term Exercise on Neurotransmission

contributor:
Noseworthy, Michael D.
Nelson, Aimee J.
Biomedical Engineering

abstract:
Aerobic exercise is recognized for its many benefits to the cardiorespiratory system, as
well as the brain. For this reason, aerobic exercise has been extensively investigated
over the last decade to understand the mechanisms involved in its beneficial effects.
However, the model of fitness-related neural plasticity remains incomplete. Purpose:
The primary goal of this thesis was to investigate the effect of long-term aerobic
exercise, in the form of cardiorespiratory fitness, on neurotransmission. In order to
achieve this goal, methodological validation was required. The secondary goal was to
investigate commonly assessed structural changes associated with exercise, to compare
with previous literature. Materials and Methods: The first experiment involved
phantom and human validation of measures of the neurotransmitter g-aminobutyric
acid (GABA) using magnetic resonance spectroscopy (MRS). Following this objective,
the second experiments recruited a total of thirty-five healthy post-menopausal women
to investigate the effect of fitness on neurophysiological and structural measures.
Transcranial magnetic stimulation (TMS) and MRS were used to evaluate GABA and
glutamate (Glu) concentrations and receptor function in the primary motor cortex (M1).
Magnetic resonance imaging (MRI) was used to assess cortical thickness (CT) and the
microstructure of white matter (WM) tracts. Results: Regression analysis found that fitness improved the microstructure in pre-motor and sensory tracts, as well as the
hippocampal cingulum in post-menopausal women. There was no effect of fitness on
CT nor neurotransmission. This suggests cardiorespiratory fitness may preserve motor
control and tactile acuity, as well as memory in post-menopausal women via
improvements in WM microstructure. Conclusion: The results provided in this thesis
can improve our understanding of how aerobic exercise and cardiorespiratory fitness
achieve their benefits in order to create efficient training programs to prevent agerelated
decline and improve prognosis of age-related disease.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Contributions to Sparse Statistical Methods for Data Integration

contributor:
Beyene, Joseph
Hamid, Jemila
Canty, Angelo
Health Research Methodology

subject:
biostatistics
statistics
genetics
genomics
sparse methods
data integration

abstract:
Background: Scientists are measuring multiple sources of massive, complex, and diverse data in hopes to better understand the principles underpinning complex phenomena. Sophisticated statistical and computational methods that reduce data complexity, harness variability, and integrate multiple sources of information are required. The ‘sparse’ class of multivariate statistical methods is becoming a promising solution to these data-driven challenges, but lacks application, testing, and development.
Methods: In this thesis, efforts are three-fold. Sparse principal component analysis (sparse PCA) and sparse canonical correlation analysis (sparse CCA) are applied to a large toxicogenomic database to uncover candidate genes associated with drug toxicity. Extensive simulations are conducted to test and compare the performance of many sparse CCA methods, determining which methods are most accurate under a variety of realistic, large-data scenarios. Finally, the performance of the non-parametric bootstrap is examined, determining its ability to generate inferential measures for sparse CCA.
Results: Through applications, several groups of candidate genes are obtained to point researchers towards promising genetic profiles of drug toxicity. Simulations expose one sparse CCA method that outperforms the rest in the majority of data scenarios, while suggesting the use of a combination of complimentary sparse CCA methods for specific data conditions. Simulations for the bootstrap conclude the bootstrap to be a suitable means for inference for the canonical correlation coefficient for sparse CCA but only when sample size approaches the number of variables. As well, it is shown that aggregating sparse CCA results from many bootstrap samples can improve accuracy of detection of truly cross-correlated features.
Conclusions: Sparse multivariate methods can flexibly handle challenging integrative analysis tasks. Work in this thesis has demonstrated their much-needed utility in the field of toxicogenomics and strengthened our knowledge about how they perform within a complex, massive data framework, while promoting the use of bootstrapped inferential measures.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Due to rapid advances in technology, many areas of scientific research are measuring multiple sources of massive, complex, and diverse data in hopes to better understand the principles underpinning puzzling phenomena. Now, more than ever, advancement and discovery relies upon sophisticated and robust statistical and computational methods that reduce the data complexity, harness variability, and integrate multiple sources of information. In this thesis, I test and validate the ‘sparse’ class of multivariate statistical methods that is becoming a promising, fresh solution to these data-driven challenges. Using publicly available data from genetic toxicology as motivation, I demonstrate the utility of these methods, find where they work best, and explore the possibility of improving their scientific interpretability. The work in this thesis contributes to both biostatistics and genomic literature, by meshing together rigorous statistical methodology with real-world data applications.


title: Accelerated Phosphorus Magnetic Resonance Spectroscopic Imaging (31P-MRSI) for the Evaluation of Energy Metabolism

contributor:
Noseworthy, Michael D.
Biomedical Engineering

subject: Phosphorus Magnetic Resonance Spectroscopy

subject: Energy Metabolism

subject: MRSI

subject: Compressed Sensing

subject: EPSI

abstract: Phosphorus magnetic resonance spectroscopy and spectroscopic imaging (31P-MRS/MRSI) non-invasively provide very important information regarding energy metabolism as they can detect high energy metabolites and membrane phospholipids in vivo. They have repeatedly proven their utility in the study of healthy and disease conditions, as many disorders  are related to imbalances in bioenergetic processes. However, they are not often used in a clinic setting as there are technical challenges that lead to very long acquisition times. To address this issue, the present work focused on the implementation of two fast phosphorus magnetic resonance spectroscopic imaging (31P-MRSI) pulse sequences. The first one, "fidEPSI" uses a flyback echo planar readout trajectory calculated in real time to achieve an acceleration factor up to x10. The second, "fidepsiCS" further accelerates the acquisition by combining the flyback EPSI readout with a compressed sensing (CS) sampling scheme.  For this latter approach two different data reconstruction processes were compared. Both sequences were tested in phantoms as well as in skeletal muscle and brain tissues of healthy volunteers. The results showed feasibility of the flyback Echo Planar Spectroscopic Imaging (EPSI) to acquire good quality data in a fraction of the time when compared to traditional phase encoded MRSI. Furthermore, the compressed sensing approach was used in an exercise-recovery paradigm to evaluate skeletal muscle high energy phosphate dynamics, achieving a temporal resolution of 9 seconds. Additionally, the comparison of CS reconstruction algorithms suggested that a low-rank approach is more suitable for 31P-MRSI data, compared to traditional thresholding, due to the fact that it exploits the sparsity of the NMR signal as the least number of spectral peaks rather than the fewest amount of non-zero values. Overall, this thesis presents new accelerated methods for the acquisition of 31P-MRSI, and its use in the evaluation of energy metabolism.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Artificial Intelligence Based Tool Condition Monitoring in Machining

contributor:
Veldhuis, Stephen C.
Mechanical Engineering

abstract: In a manufacturing environment, gradual and catastrophic failure of a cutting tool are common faults associated with a machining process. Left unmonitored these failures exhibit a high likelihood of triggering workpiece surface quality issues and reducing the overall productivity of the process. This research offers a comprehensive study of the design, development and implementation of a low-cost artificially intelligent (AI) tool condition monitoring (TCM) system for the turning operation of different workpiece material. As the characteristics of the signals from the fusion of multiple sensors differ from each individual sensor, fast Fourier transform (FFT) and wavelet transform (WT) were used to identify signal features which provided the most useful information about the cutting tool conditions. Pearson correlation coefficients (PCC) and principal component analysis (PCA) singled out the most sensitive features from the sensor fusion signals which play a pivotal role in monitoring gradual tool wear (flank wear) progression during machining. Experimental results indicated that the total harmonic distortion (THD), crest factor of the spindle motor current and certain spectral features from the vibration sensor signal had a significant correlation with cutting tool flank wear under different cutting conditions and when machining different materials. Furthermore, a data-driven artificial neural network (ANN) and an adaptive neuro-fuzzy inference system (ANFIS) were studied to investigate their prediction accuracy for cutting tool conditions (tool wear). The ANFIS prediction model outperformed the ANN prediction in terms of accuracy. As a result, the developed (trained and validated) ANFIS based TCM system was implemented in the material turning process. In addition, the adaptability of the supervised ANFIS based TCM system was shown to further increase the reliability of tool wear prediction.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: APPLICATION OF SUPERABSORBENT COOLANT AS A NOVEL APPROACH TO SEMI-DRY MACHINING

contributor:
Veldhuis, Stephen Clarence
Mechanical Engineering

abstract:
Cutting fluids play a significant role in manufacturing processes. Machining certain materials is impossible without them. Due to high temperature and friction during cutting operations, proper cooling and lubrication are necessary to improve the efficiency, quality of the final workpiece and to reduce tool failure costs.
This study presents a novel coolant suitable for different machining processes. The focus of this work is the application of a superabsorbent coolant (SAC) during hardened H13 steel machining, Inconel 718 turning, and aluminium silicon alloy tapping and drilling with an uncoated carbide tool. Hence, different machining operations have been attempted to better understand the range of function for SAC. Moreover, the possibility of superabsorbent material use as a coolant has been evaluated in comparison with dry and flood conditions. The use of SAC is a novel method of semi-dry machining that demonstrates the advantages of hydrogels as a coolant and opens a new window for industrial applications. SAC is a superabsorbent polymer enriched by a nanofluid and injected near the cutting zone. Its main purpose, besides improving machining performance, is to safely provide beneficial properties of nanoparticles (higher thermal conductivity and lubricity) and to prevent their distribution in air, which along with other chemical additives, can cause serious occupational and environmental hazards. The results of machining studies indicate that SAC can considerably reduce the friction conditions in the cutting zone, greatly reducing cutting force, while improving surface integrity and enhancing tool life. In addition, the friction conditions at the cutting zone have been improved. Ultimately, chip undersurface roughness was measured to ensure the penetration of the nanoparticles into the cutting region and to reduce friction between the tool and chip. The results show a lower surface roughness of the chip surface.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: ELUCIDATING TCF7 AND TCF7L1 FUNCTIONS AND GENE REGULATORY MECHANISMS IN MOUSE EMBRYONIC STEM CELLS

contributor:
Doble, Bradley
Biochemistry and Biomedical Sciences

subject:
Stem Cells
Wnt
TCF/LEFs

abstract:
Wnt signaling regulates critical cellular interactions throughout normal development and directs cell fate decisions of stem cells. Previous work by our lab implicates -catenin as an essential modulator of embryonic stem cell self-renewal and differentiation. Genetic studies in mice have demonstrated broad functional redundancies between the most downstream effectors of the Wnt signaling cascade, the T-cell factor / Lymphoid enhancer factor (TCF/LEF) family of transcription factors. Despite this, loss-of-function experiments suggest that -catenin reinforces the pluripotent state by mediating a TCF switch in which repressive TCF7L1 is replaced with activating TCF7. However, these experiments do not account for potential confounding functional compensation by other TCF/LEF factors. As such, I hypothesized that TCF7 and TCF7L1 are functionally redundant in mouse embryonic stem cells and bind a largely overlapping set of target genes and interacting proteins.
In support of this notion, we demonstrated that both TCF7 and TCF7L1 were similarly able to restore the altered transcriptomic profile and differentiation deficits observed in mouse embryonic stem cells (mESCs) lacking all full-length TCF/LEFs. With the expectation that TCF7 and TCF7L1 recruit similar transcriptional co-regulators to a broadly overlapping set of target genes, we employed the unbiased techniques, ChIP-seq and BioID to test our hypothesis. We observed that regardless of the degree of Wnt signaling activity, TCF7L1 was more abundantly associated with chromatin than TCF7, and TCF7 and TCF7L1 regulate distinct target genes. We demonstrated that Wnt stimulation, simulated by GSK-3 inhibition, facilitates TCF7L1 interactions with transcriptional modulators such as the BAF and nuclear receptor co-repressor complexes, despite a reduction in TCF7L1 levels. Taken together, the work in this thesis provides new insights into the mechanisms of Wnt target gene regulation by the TCF/LEF factors.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Stem cells are capable of giving rise to multiple different cell types and thus are able to generate all adult tissues. The identity of a cell is controlled by external signals that regulate internal programs encoded by our genes. The execution of the instructions in genetic programs is conducted by proteins called transcription factors that can turn different genes on or off, giving rise to distinct cell types. The T-Cell Factors and Lymphoid Enhancer Factor (TCF/LEFs) are a family of four transcription factors regulated by external signaling molecules called Wnts. By using the TCF/LEFs, Wnts establish gene outputs that determine the identity of cells throughout embryonic development and in adult tissues. However, the mechanisms used by this family of transcription factors to establish the programs controlling cellular identity remain poorly understood. Using genetically engineered mouse embryonic stem cells, we have uncovered new information about the mechanisms TCF/LEFs use to regulate gene function, identified programs controlled by TCF/LEFs, and discovered potential protein partners that work with TCF/LEFs to implement genetic programs. This thesis provides novel insights into the control of cell identity by the TCF/LEFs, which has implications for the numerous human diseases linked to abnormal Wnt-mediated signaling.


title: Investigation on Improved Tapping Life in Automotive Die Cast Aluminum-Silicon Alloy Applications

subject:
Form tap
Automotive
Aluminum Silicon alloys
PVD coatings
Wear mechanisms
Threading
Tapping

abstract:
In the automotive industry, Al-Si alloy is widely used for manufacturing of various engine parts. Machinability of die-cast Al-12Si alloy is challenging due to severe abrasion and adhesion wear of the tools. Form tapping is a common method for generating internal threads in engine blocks. It is usually a finishing process on a production line. An unexpected tap failure may lead to significant scrap and high rework costs.
The objective of this research was to investigate the wear mechanisms of high-speed steel form taps when machining Al-12Si alloy. This research involved replicating the same process conditions as the industry partner to determine a feasible solution without changing the tap geometry or process parameters.
A critical region of wear on the crest was identified where the aluminum adhesion was acute. Intense abrasion wear occurred on the crest and flanks due to hard silicon precipitates. In this study, two methods were proposed for measuring linear and volumetric wear on the chamfered threads. The second and third chamfered threads experienced the most significant wear on the tap.
To improve wear-resistance of the form tap, PVD surface coatings were deposited on it. The preliminary tests of 12 surface coatings showed coating-delamination mostly on the critical region. A progressive wear study of the TiAlN coating showed an improvement in tap performance over the ZrN coating currently used. By the 4320th  hole, the volumetric wear of the TiAlN coated tap was reduced by nearly 200% and 50% when compared against the uncoated and ZrN coated taps, respectively.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: The Role of Thrombin Exosites 1 and 2 in the Activation of Factor XI by Thrombin

contributor: Medical Sciences (Thrombosis & Haemostasis & Atherosclerosis)

subject: FXI Thrombin Coagulation Anticoagulants Exosites Hemostasis Thrombosis

abstract:
Factor XI (FXI) is the zymogen of the coagulation protease factor XIa (FXIa) that contributes to thrombin generation through the intrinsic pathway. FXI is activated by the contact pathway protease, factor XIIa (FXIIa), in a high molecular weight kininogen-dependent manner. It is also known to be activated by thrombin in a positive feedback reaction, however, the mechanism of this activation is not yet completely understood. Therefore, our objectives were to identify the role of polyanions in the thrombin mediated FXI activation, and the role of the thrombin exosites in the activation.
To study this activation, we assessed the activation of FXI by thrombin in the presence and absence of the polyanions, dextran sulfate and polyphosphate (polyP). We utilized surface plasmon resonance to determine whether FXI and thrombin bind to the polyanions, and how the exosites effect thrombin’s ability to bind using thrombin exosite 1 and 2 variants. To investigate the role of the exosites in FXI activation, we analyzed the activation of FXI by the thrombin variants. In addition, we explored how inhibiting the thrombin exosites using DNA aptamers affects thrombin’s ability to bind to polyanions and activate FXI.
We found that polyanions are required as a cofactor for the activation of FXI by thrombin, and stimulate the activation in a concentration dependent fashion, suggesting a template mechanism. Our findings also show that exosite 1 and 2 are required for thrombin to bind to polyanions, however, exosite 2 plays the predominant role in FXI activation. Our aptamer data showed that either exosite can be targeted to inhibit FXI activation. These findings enrich our understanding of the mechanism of FXI activation by thrombin and provides further insight on how to attenuate the activation for potential antithrombotic therapies.

abstract: Thesis

abstract: Master of Science (MSc)