title: Kinematic Enveloping Grasp Planning Method for Robotic Dexterous Hands and Three-Dimensional Objects

contributor:
Bone, Gary M.
Mechanical Engineering

subject: robot hand dexterous 3D

abstract: Three-dimensional (3D) enveloping grasps for dexterous robotic hands possess several advantages over other types of grasps. However, their innate characteristics such as the several degrees of freedom of the dexterous hand, complexity of analyzing the 3D geometry of the object to be grasped or detecting the 3D contact points between the object and the hand make planning them automatically a very challenging problem. This thesis describes a new method for kinematic 3D enveloping grasp planning for a three-fingered dexterous hand. The required inputs are the geometric models of the object and hand; and the kinematic model of the hand. The outputs are the position and orientation of the palm and the angular joint positions of the fingers. The method introduces a new way of processing the 3D object. Instead of considering the object as a whole, a series of 2D slices (vertical and horizontal) of the object are used to define its geometry. This method is considerably simpler than other methods of object modeling and its parameters can be easily setup. A new idea for grading the object's 3D grasp search domain is proposed. The grading system analyzes the curvature pattern and thickness of the object and grades object regions according to their suitability for grasping. The proposed method is capable of eliminating most of the ungraspable areas of the object from the grasp search domain at the early stages of the search. This improves the overall efficiency of the search for a grasp. In modeling a dexterous hand a new method is proposed to model the fingers. In this model each finger is modeled by three articulated line segments, representing the top, centre and bottom of the finger. This model has significant benefits that it is efficient and does not need the exact coordinate of the 3D contact point between the finger and the object to analyze the feasibility of the grasp. The new grasp planning method was implemented by writing a 4300 line MATLAB program. The program has been run successfully with several 3D objects. These results are documented.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Surface Immobilization of Natural Wetting and Lubricating Agents for the Development of Novel Biomimetic Contact Lenses

contributor:
Sheardown, Heather
Chemical Engineering

subject:
surface modification
contact lenses
biomimetic surface
hyaluronic acid
proteoglycan 4

abstract:
Despite the effort to optimize soft contact lens performance, almost half of the 140 million contact lens wearers worldwide experience symptoms of ocular dryness and discomfort, especially towards the end of the day. These symptoms are attributed to reduced compatibility between the contact lens and the ocular surface and are the main reason for contact lens discontinuation. As the interactions of the contact lens-eye interface are dynamic, the surface properties play a key role in improving ocular compatibility, comfort and overall performance of contact lenses. One promising method to reduce adverse interfacial interactions between the contact lens and the ocular surface is to modify the contact lens surface with a biomimetic layer inspired by the ocular surface and the tear film. Hyaluronic acid (HA) is a non-sulfated glycosaminoglycan naturally found in the ocular environment providing ocular hydration and lubrication. Proteoglycan 4 (PRG4), a mucin-like glycoprotein naturally produced at the ocular surface contributes to natural lubrication during blinking and to tear film stability. Surface modification with HA or PRG4 has been shown to result in improved wetting, lubricating and antifouling properties. Moreover, HA and PRG4 have been previously found to interact and synergistically reduce friction further.
In the current work, novel HA and PRG4-grafted soft contact lens surfaces were prepared, and the impact of the surface tethered layer on important contact lens properties was assessed. Furthermore, the potential synergistic effect between HA and rhPRG4 on the examined properties was evaluated.
Surface immobilization of HA on model conventional (pHEMA) and silicone (pHEMA-co-TRIS) hydrogel contact lenses was achieved by thiol-ene “click” chemistry, while full-length recombinant human PRG4 (rhPRG4) was surface grafted via carbonyldiimidazole (CDI) linking chemistry respectively. The chemical structure after each modification step was determined by attenuated total reflectance FTIR (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS) analyses. HA-grafted model soft contact lenses were characterized by improved surface wettability, antifouling and water retentive properties, while a decreasing trend in boundary friction was observed but only for the HA-grafted pHEMA-co-TRIS materials. Surface-tethering of rhPRG4 was found to effectively enhance the surface wettability and boundary lubricating properties of pHEMA-co-TRIS hydrogels only, whereas both rhPRG4-grafted pHEMA and pHEMA-co-TRIS materials exhibited lower protein sorption and dehydration rate. Overall, the surface immobilization processes followed herein did not alter the optical transparency of the model soft contact lenses or their in vitro compatibility with human corneal epithelial cells. Finally, there was evidence that HA and rhPRG4 synergistically interacted, further improving the contact lens properties. However, the degree of HA/rhPRG4 synergy was found to be dependent on the configuration of the formed HA/rhPRG4 complex as well as the composition of the substrate hydrogel material, with the noted improvement being more significant for the model silicone hydrogels.
This is the first study to examine surface grafted full-length rhPRG4 and the effect of this modification on contact lens properties. Moreover, the study is the first to investigate the interactions between covalently tethered rhPRG4 and solutions containing HA. The results of this thesis demonstrate that HA and rhPRG4 are good candidates for the development of novel biomimetic surfaces, especially for silicone hydrogel contact lenses. The potential for using these compounds in synergy was also demonstrated, with wetting solutions of HA showing promise for modifying rhPRG4 modified materials to improve symptoms of discomfort. These naturally occurring ocular agents have the potential to improve the management of ocular dryness and discomfort, thus optimizing the overall soft contact lens performance.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: HEALTHCARE SERVICE UTILIZATION IN THE LAST 2 WEEKS OF LIFE: A POPULATION-BASED COHORT STUDY OF  ONTARIO DECEDENTS

contributor:
Seow, Hsien
Health Research Methodology

subject: service utilization, health services research, palliative care, end-of-life care, place of care, acute care

abstract:
Background: Place of death is a commonly reported indicator for assessing palliative care quality, but does not provide details of healthcare service utilization at the end-of-life, such as acute care. In particular, early palliative care has shown to reduce acute care service use, but findings are mostly limited to cancer patients with few population-based data available.
Objectives: The purpose of this research is to: 1) explore place of care trajectories in the last 2 weeks of life in a general population and among distinct illness cohorts, and 2) investigate whether early versus late palliative care affects acute care use and other publically-funded services in the last 2 weeks of life.
Research Design: A retrospective population-based cohort study using linked administrative health data to examine all Ontario decedents between April 1st, 2010 and December 31st, 2012.
Methods: Descriptive statistics were used to examine place of care trajectories and service utilization trends in the last 2 weeks of life. Multivariable logistic regression analyses were conducted to assess in the 2 weeks before death: 1) the odds of using an acute care setting (yes/no), and 2) the odds of time spent (≤1 week or >1week) in acute care settings among users.
Results: Overall, 235,159 decedents were identified. About 32% had cancer, 31% had organ failure, and 29% had frailty. Overall, 29% of decedents used a hospital two weeks before death, but this increased to 61% on the day of death. Those with cancer were the largest users of palliative-acute hospital care, while those with organ failure were the largest users of acute- hospital care. Assessing palliative care timing, 27% were early palliative care recipients, 13% were late. About 45% of early recipients had a community-based palliative care initiation, 74% of late recipients had a hospital-based initiation. Late recipients were more likely to use acute care settings; this was further modified by disease: comparing late to early recipients, cancer decedents were nearly two times more likely to spend >1 week in acute care settings (OR=1.84, 95%CI:1.83-1.85), frailty decedents were three times more likely (OR=3.04, 95%CI:3.01-3.07), and organ failure decedents were four times more likely (OR=4.04, 95%CI:4.02-4.06).
Conclusion: Place of care trajectories differ greatly by disease cohort. Exploring place of care trajectories can provide details not evident when reporting solely place of death. Furthermore, early palliative care was associated with reduced acute care service use in cancer and non-cancer patients. Late initiations were associated with greater acute care use, and had the largest effect on those with organ failure and frailty, suggesting potential opportunities for improvement in non- cancer populations.

abstract: Thesis

abstract: Master of Science (MSc)


title: The Modeling and Simulation of High-Speed Continuous and Discontinuous Chip Formation in the Machining of AISI 4340 Steel

contributor:
Elbestawi, M. A.
Metzger, D. R.
Mechanical Engineering

subject:
chip
formation
continuous
discontinuous
aisi 4340 steel
model
simulation

abstract: Throughout engineering history, metal cutting technology has been pushed to keep pace with the development of stronger and more difficult to cut materials. With the advent of robust machining technology, the finish cutting of hardened materials at high speeds and extreme conditions has become possible. As we push the thresholds of our technology, the need for a deep understanding of the processes at work in metal cutting in order to predict limit states has become clear. The prediction of machining processes began with models that described the problem qualitatively. The principals and assumptions used within these laid the foundations for further theoretically based empirical models. With the advent of computationally based numerical modeling, predictive modeling of metal cutting processes using elasto-plastic based simulation has brought a new perspective to the field. The development of finite element modeling techniques capable of modeling both continuous and discontinuous chip formation has become a subject of considerable research effort. The present work focuses on the study and development of explicit transient finite element techniques used to simulate the orthogonal machining of hardened steel under various cutting conditions producing both continuous and discontinuous chips. Metal cutting involves a diversity of complex physical phenomenon such as large strain and strain rate plasticity, high temperature contact and friction conditions, material failure, adiabatic shear localization, and thermo-mechnically based deformation. The numerical modeling of these processes in orthogonal machining operations is the primary focus of this work. The effects of cutting conditions on chip morphology and the finished workpiece are investigated and resulting phenomenon are explained in terms of numerically based stress analysis. Benchmarking comparisons with literature and commercial modeling software simulations are made and quantified in terms of strains, temperatures, residual stresses, and the various components of stress. Future directions and issues are outlined and recommendations are made. Solution stability of the finite element solver applied to machining was quite low due to the lack of an adaptive remeshing scheme and deficiencies in the contact algorithm. Thermal mechanical coupling and remeshing are currently being implemented. Future avenues include methods of surface generation without volumetric losses. the application of friction based on wear data, and the application of machining simulations to oblique three-dimensional cutting operations.

abstract: Thesis

abstract: Master of Engineering (ME)


title: Signalling Pathways Regulating BC₃H1 Cell Myogenesis

contributor:
Lee, R. W. H.
Biology

subject: signal pathway BC₃H1 cell myogenesis

abstract:
The myogenic cell line, BC₃H1, upon cell-to-cell contact or serum starvation differentiates as monitored by the appearance of muscle-specific markers, actin, myosin light chain 1 (MLC 1) and tropomyosin (Tm) and morphological changes. The detection of MLC 1 and five Tm isoforms in this cell line is novel. To assess the role of protein kinase C (pk C)-and protein kinase A (pk A) signal transduction pathways in controlling BC₃H1 cell differentiation, activators of pk C (TPA) and pk A (cAMP analogues, dibutyryl-cAMP and 8-Br-cAMP) were used. TPA
(500nM) addition caused no deviation from the normal expression patterns of actin, Tm and MLC 1. Addition of cAMP analogues (500μM) delayed the appearance of MLC 1 and muscle-specific isoforms of Tm, as well as α-actin while  β- and γ-actin levels remained unchanged. However, α-actin mRNA levels were not affected by cAMP analogues yet the typical β- and γ-actin mRNA downregulation was blocked. cAMP appears to be operating at multiple levels to regulate BC₃H1 cell myogenesis such as post-transcriptional and translational. In addition, given the similarity in mechanisms through which cAMP and adenovirus early region 1A (AdE1A) mediate gene activation, the effect of AdE1A on BC₃H1 cell differentiation was investigated. A stable transfected AdE1A clonal cell line, BC₃E7, was characterized. Together with altered morphology, BC₃E7 cells failed to show the characteristic expression of muscle-specific markers actin, Tm and MLC 1. AdE1A transfection disrupted the synchronous expression of muscle-specific proteins during BC₃H1 cell differentiation.

abstract: Thesis

abstract: Master of Science (MS)


title: Construction and Characterization of HSV-1 Mutants Encoding Truncated VP16 in the Presence and Absence of Functional VHS

contributor:
Capone, John
Biochemistry

subject: construction mutant VP16 VHS absence presence

abstract: VP16 is an integral element in the HSV-1 strategy to overturn normal cellular functions and use the host machinery for the production of new virus. VP16 enhances the expression of viral immediate-early genes in the nucleus of the infected cell. By binding to the virion host shutoff protein (vhs), VP16 is able to downregulate its activity and prevent destruction of the viral transcripts. Finally, VP16 has an essential but specifically undetermined role in virus assembly. While a null mutation in VP16 correlates to a lethal defect in virus assembly, recent work has revealed that the C-terminal acidic activation domain of VP16 is not essential to virus survival. Viral mutants containing 422 and 379 amino acid tail-deleted derivatives of VP16 are viable. We have constructed a viable viral mutant which encodes a 369 amino acid VP16, revealing that the N-terminal 369 amino acids of VP16 retain a function which is essential to virus survival. The viral mutants encoding truncated VP16 derivatives displayed a characteristic preference for growth on a cell line which supplied full length VP16 in 𝘵𝘳𝘢𝘯𝘴. Furthermore, the preference for growth on the complementing cell line became more apparent as VP16 was progressively truncated from the C-terminus. To determine if full length VP16 was aiding these virtues in attenuating vhs activity or in performing a structural role in the presence of vhs, we constructed double mutant viruses encoding the truncated VP16s and containing an inactivating mutation in the vhs locus (ΔSma). The elimination of vhs activity and/or vhs-VP16 binding alleviated the preference for growth on the complementing cell line in these viruses. Thus, while the acidic activation domain of VP16 is not essential for viral replication in tissue culture, it clearly confers a growth advantage to the virus. The viral mutants constructed here will prove useful in understanding the significance of the interaction between VP16 and vhs.

abstract: Thesis

abstract: Master of Science (MS)


title: Dithiocarbamate-Mediated Uptake of Nickel(II) By Cells In Vitro

contributor:
Nieboer, Evert
Biochemistry

subject:
dithiocarbamate
nickel
uptake
cell
in vitro

abstract: Dithiocarbamate-mediated nickel(II) uptake was studied in five cell lines: 1) cultured human B-lymphoblasts, 2) rabbit alveolar macrophages, 3) human peripheral lymphocytes, 4) human erythrocytes and 5) human polymorphonuclear leukocytes. Two different incubation protocols were employed: concurrent incubation of nickel(II) with the ligand, and sequential incubation of ligand followed by nickel(II) incubation. The effects of various experimental parameters such as ligand concentration, cell number and available nickel(II) concentration on nickel (II) uptake were examined for most of the above cell types. During concurrent incubations, the effect of ligand concentration on nickel (II) was maximum at 10⁻⁶ M sodium diethyldithiocarbamate (DDC) or ammonium pyrrolidinedithiocarbamate (APDC) for all cell types (except polymorphonuclear leukocytes). Enhanced uptake was evident at higher concentrations (≥ 10⁻³ M DDC or APDC) for sequential incubations. By contrast, ammonium dithiocarbamate (AD) had no enhancing effect on nickel(II) uptake in either protocol (tested only for human peripheral lymphocytes and human erythrocytes). Distribution studies indicated that enhanced cytosolic uptake of nickel(II) occurred for 10⁻⁷ - 10⁻⁵ M DDC. The observed effects on nickel (II) uptake of ligand concentration, Ni² concenration and cell number were interpreted on the basis of an 'Equilibrium Model' with several possible pathways. The nickel(II) uptake data were consistent with the possibility that ligand uptake precedes metal-ion uptake. The latter process may well involve the protonated form of the dithiocarbamate as an ionophore. As a means of enhancing cell-associated nickel(II), peripheral lymphocytes from nickel-sensitized and non-sensitized individuals were pretreated with APDC in veronal buffer. The transforming ability of these cells were then studied by use of a lymphocyte transformation (proliferation) test. This approach was not successful in enhancing the response to nickel (II) because of the inherent toxicities of the veronal buffer and APDC.

abstract: Thesis

abstract: Master of Science (MS)


title: The Impact of Nitrogen and Energy Reserve Depletion on Feeding and Drinking in the American Cockroach, Periplaneta americana (L.) (Orthoptera: Blattidae)

title: Nitrogen and Energy Depletion in the American Cockroach

contributor:
Rollo, C. D.
Biology

subject: nitrogen energy cockroach reserve depletion drink eat

abstract:
Selective feeding in response to depletion of particular reserves was examined in the American cockroach, Periplaneta americana. Animals deprived of specific nutrients and subsequently provided with dietary choices, responded so as to restore their altered reserves. Since two foods of differing energy content were used, the fundamental hypothesis of optimality theory could be tested (i.e. do cockroaches behave so as to maximize energy intake?). Adult male cockroaches were placed in a computer-monitored artificial habitat containing routes to shelter, water, protein and carbohydrate. Measures of behaviour were compared over treatments. Treatments included control cockroaches (no starvation), cockroaches fed agar (originally fed protein and sugar), protein-starved cockroaches (originally fed sugar only) and starved cockroaches (no food in the pre-treatment).
In all treatments, more time was spent feeding than drinking. In controls, feeding on carbohydrate took precedence over protein (for intake and duration). Protein-starved cockroaches showed increased intake (over controls) for protein, as expected, but also increased intake for both carbohydrate and water. Starved and agar-fed cockroaches displayed decreased carbohydrate and water intake while protein consumption increased. The compensatory responses showed large initial peaks that gradually approached control behaviour. The results indicate that feeding behaviour is strongly responsive to reserve state and reserves act as an integral part of a dynamic system which operates homeostatically. The fact that depletion of the protein reserve resulted in increased ingestion of both protein and carbohydrate strongly suggests that reserves are linked. Considerable variation in daily feeding was observed which may be related to overshoot/undershoot responses typical of homeostatic systems where time lags exist. The results are strongly at variance with the predictions of optimal foraging theory. Cockroaches appear to feed to homeostatic set points, largely regulated by reserves. Reserves are largely ignored in optimal foraging theory. Furthermore, the animals regulate intake of nitrogen (protein) and/or energy, and do not simply maximize energy intake.

abstract: Thesis

abstract: Master of Science (MS)


title: Study of Fluid Flow and Cavitation Inside Torque Converters

contributor:
Hamed, Mohamed
Mechanical Engineering

subject:
fluid
cavitation
torque
convert
fluid flow

abstract: Cavitation inside an automotive torque converter running at various pump speeds was simulated by using the Computational Fluid Dynamics (CFD) commercial package ANSYS-CFX 10.0/11.0. The numerical solution obtained for the case with no cavitation was used as an initial condition for the case of flow with cavitation to accelerate convergence. The converter was initially modeled using several grid sizes to evaluate the effect of grid density on the numerical solution and to select the optimum grid size for subsequent simulations. Comparison of CFD to actual test results demonstrates that the cavitation model built in the commercial code, which was developed by Zwart et. al. (2004) based on the simplified Rayleigh-Plesset equation of bubble dynamics, does not capture the full effect of cavitation inside the converter. Modifications to this model have been investigated in this study. The effect of the variation of the automotive transmission oil vapor pressure due to the rise in temperature during normal operating conditions was also investigated and found not to cause any significant change to the area of vapor formation, and hence did not have a significant effect on the converter performance. Values of the empirical coefficients of the cavitation model had to be modified in order for the model to capture the full effect of cavitation on the performance of the converter operating at high pump speeds. Results showed a much larger area of vapor over the converter stator and traces of vapor appeared inside the pump, and turbine blades. With these modifications, the model produced results in better agreement with the available experimental data. Moreover, simulations have been carried out in both steady and transient states using various turbulence models available in CFX10.0/11.0 in order to evaluate the effect of the choice of turbulence models on cavitation prediction.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Microfluidic Devices for Cell Based High Throughput Screening

contributor:
Selvaganapathy, Ravi
Mechanical Engineering

subject: microfluid cell screening throughput

abstract: Cell based High Throughput Screening (HTS) has become a very important method in pharmaceutical drug discovery and presently carried out using robots and well plates. A microfluidics based device for cell based HTS using traditional cell culture protocol would be a significant addition to the field. In this thesis novel microfluidic HTS devices targeted for cell based assays having traditional non-compartmentalized agar gel as cell culture medium and electric control over drug dose is being reported. The basic design of device consists of a gel layer supported by a nanoporous membrane that is bonded to microchannels underneath it. The pores of membrane are blocked everywhere except in selected regions that serve as fluidic interfaces between the microchannel below and the gel above. Upon application of electric field nanopores start to act as electrokinetic pumps. By selectively switching an array of such micropumps, a number of spots -containing drug molecules- are created simultaneously in the gel layer. By diffusion drugs reach to the top surface of gel where cells are to be grown. Based on this principle, a number of different devices are fabricated using microfabrication technology. The fabricated devices include, single drug spot forming device, multiple drug spot forming device and microarray of  drug spots forming device. By controlling pumping potential and duration spots sizes ranging from 200μm to 6mm diameter and having inter-spot distances of 0.4mm-10mm have been created. Absence of diffusional transport through the nanoporous interfaces without electric field is demonstrated. A number of representative molecules, including surrogate drug molecules (trypan blue, and methylene blue) and biomolecules (DNA and protein) were selected for demonstration purpose. Dosing range of 50-3000 μg and spot density of 156 spots/cm² were achieved. The drug spot density was found to be limited by molecular diffusion in gel and hence numerical study was carried to find out ways for density increase. Based on this simulation, a method for diffusion reduction called diffusion barrier was proposed. Diffusion barrier used specially dimensioned (having shallow grooves) gel sheet to reduce the diffusion.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Richard Outram’s Early Poems (1957-1988): A Critical Introduction with Annotations

contributor:
Donaldson, Jeffery
English and Cultural Studies

subject:
Outram, Richard Daley (1930-2005)
critical editions
Howard, Helen Barbara (1926-2002)
Canadian poetry
The Gauntlet Press
private presses
poetry and poetics
textual scholarship

abstract: The thesis comprises an introduction and annotations to Collected Poems of Richard Outram, Volume One (1957–1988), a planned critical edition of the poems of Richard Outram (1930-2005), Canadian poet and printer. It tells the story of Outram’s published oeuvre, beginning in 1957, when he published his first work in collaboration with his wife, the artist Barbara Howard (1926–2002), up through 1988, when Outram and Howard published the last of their hand-printed, letterpress collaborations. Jernigan asserts that Outram’s oeuvre is characterized by a reiterative poetics, in which the poet “reads” individual poems into the public record of his work on multiple occasions, allowing the poems’ meanings to be shaped by the changing context of an unfolding oeuvre, as well as by changes in material context and addressed readership — an assertion reflected in the structure of her edition. At the same time, she speaks to the collaborative context of Outram’s published work, all of which was made in explicit or implicit conversation with his wife, the artist Barbara Howard (1926 – 2002), while also being shaped by the sorts of communal forces famously noted by D.M. Mackenzie. Both the introduction and the annotations demonstrate the close link between composition and publication for Outram, poet-printer. In her introduction, Jernigan considers how this link complicates the traditional dichotomy between genetic and bibliographic approaches to textual criticism. Throughout, Jernigan establishes an updated bibliographical and biographical context for Outram’s work, enlarging upon the seminal scholarship of Peter Sanger, and contributes to the existing scholarship on Outram’s personal and publishing life with new archival research in the Gauntlet Press fonds at Library and Archives Canada, the Richard Outram papers at the Thomas Fisher Rare Book Library, the Allan and Nancy Fleming fonds at York University, and the Macmillan and Key Porter fonds at McMaster University.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: The thesis comprises an introduction and annotations to Collected Poems of Richard Outram, Volume One (1957–1988), a planned critical edition of the poems of Richard Outram (1930-2005), Canadian poet and printer. It tells the story of Outram’s published oeuvre, beginning in 1957, when he published his first work in collaboration with his wife, the artist Barbara Howard (1926–2002), up through 1988, when Outram and Howard published the last of their hand-printed, letterpress collaborations. Both the introduction and the annotations demonstrate the close link between composition and publication, for Outram, and show the deep effect on Outram’s poetics of his longterm collaboration with his wife. The annotations map the interaction, through three decades, of Outram’s commercial- and private-publishing practices, and cast new light on his lifelong practice of reiteration: his habit of reading his own, older poems into the record of his unfolding work again, in new contexts, linking old work to new, and enriching the meanings of both.


title: 3D Vision Measurement System for Intelligent Open-Die Forging Center

contributor:
Nye, Tim
Mechanical Engineering

subject: 3D vision intelligent open-die

abstract: In this thesis, a 3-D vision system is established to conduct the real-time measurement task for intelligent-open-die forging center. This system consists of a CCD camera, a slit alaser projector and a Kawasaki JS 6-axis robot all interfaced to a PC for image processing. The linear structured light technique is employed for data acquisition. An optical filtering algorithm for laser stripe segmentation is developed to locate the stripe peak positions to sub-pixel accuracy. A new calibration method is proposed to determine the mapping correspondence from 2-D image pixels to 3-D reference points. A cylindrical scanning scheme is applied to gather data about the 3-D shape of parts, so that the overlap problem is easily avoided. Finally, the cross-section at any place along the height of a workpiece is reconstructed so as to detect shape error for adaptive control of automated open-die forging. This vision system is low-cost, accurate and reliable. A cylinder shape has been successfully reconstructed and measured with it. The experimental results illustrating its performance are reported and discussed.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Characterization of Factors Affecting the Virion Host Shutoff Function of Herpes Simplex Virus

title: Factors Affecting Virion Host Shutoff in HSV-1 & HSV-2

contributor:
Smiley, James
Biology

subject: virus host virion HSV-1 HSV-2 shutoff

abstract: Herpes Simplex virus (HSV) virions contain the protein vhs (virion host shutoff), which is known to trigger rapid shutoff of host protein synthesis and accelerated decay of viral and cellular mRNAs. HSV-1 strains generally cause weaker shutoff than HSV-2 strains. HSV viruses lacking the VP16 viral transactivator gene show uncontrolled shutoff late in infection (Lam et al., 1996); vhs is known to bind to VP16 (Smibert et al., 1994). In vitro experiments demonstrated that HSV-1 vhs protein (vhsTl) and an intertypic HSV-2 G vhs protein (vhsT2) did not differ in ability to effect mRNA degradation in a rabbit reticulocyte lysate (RRL) assay system, suggesting that virion factors might influence vhs shutoff phenotype. To investigate the possibility that VP 16 influences early shutoff during HSV infection, a virus was constructed containing the HSV-2 strain G VP16 in place of HSV-1 VP16. This virus (8MA2R) grew in a noncomplementing cell line and was unaltered in shutoff phenotype compared to wt strain. Cotransfection assays demonstrated vhsT2 had greater shutoff ability than vhsT1, and this was confirmed in a viral system by constructing intertypic viruses containing portions of the HSV-2 G vhs ORF in a vhs-null HSV-1 tk locus. All intertypic constructs conferred increased shutoff ability relative to vhsT 1, indicating that the strong shutoff ability of HSV -2 vhs is distributed along much of the vhs ORF. Also, to confirm the observation that UL13 null viruses show a lack of shutoff which is not due to lack of vhs in the virion (Overton et al., 1994) a number of wildtype viruses and their UL13-null derivatives were tested for ability to shutoff host translation. All showed near-wt or wt levels of shutoff.

abstract: Thesis

abstract: Master of Science (MS)


title: Dynamically-Crosslinked Self-Assembled Smart Microgels for Drug Delivery

contributor:
Hoare, Todd
Chemical Engineering

subject:
drug delivery
microgels
polymers
self-assembly

abstract:
Microgels, colloidal networks of crosslinked water-soluble polymers with dimensions < 1 μm, have been demonstrated to be useful materials in a wide range of biomedical and environmental applications. In particular, temperature-responsive microgels based on poly(N- isopropylacrylamide) (PNIPAM) have attracted significant research interest in drug delivery applications. However, conventional precipitation-based PNIPAM microgels are functionally non-degradable, problematic for biomedical applications. To resolve this issue, a thermally- driven self-assembly approach based on hydrazide and aldehyde functionalized PNIPAM oligomers to form an acid-labile hydrazone bond was developed in the Hoare Lab to produce thermoresponsive, colloidally stable, monodisperse and degradable microgels.
In this thesis, the internal structure of these self-assembled microgels was investigated using small and ultra-small angle neutron scattering and surface force experiments. Contrary to expectations based on the assembly technique, all these characterization strategies suggested that self-assembled microgels have a homogeneously cross-linked internal structure. It is anticipated that these well-defined degradable and homogeneous nanoscale gel networks offer opportunities for addressing challenges in drug delivery, biosensing, and optics by exploiting the predictable diffusive and refractive properties of the homogeneous microgel networks. In addition, the co-self-assembly of a moderately hydrophobic anti-inflammatory drug (dexamethasone) during the microgel self-assembly process was demonstrated to enable five-fold higher drug encapsulation (75-80%) relative to the conventional partition/diffusion- based drug loading processes. This result addresses a key challenge in delivering hydrophobic drugs using conventional precipitation-based microgel systems due to the inherent hydrophilicity of the crosslinked network.

The potential of the self-assembly approach to fabricate multi-responsive smart microgels was demonstrated by incorporating pH-ionizable functional groups (via the copolymerization of acrylic acid and 2-dimethylaminoethylmethacrylate to introduce anionic and cationic charges respectively) into the hydrazide and aldehyde-functionalized precursor polymers prior to self-assembly. The self-assembled charged microgels showed the same pH- responsive swelling behaviours of conventional microgels, including amphoteric microgels that can be formed at any desired cationic:anionic charge density by simply mixing different ratios of cationic and anionic precursor polymers. Such microgels offer significant potential to improve the performance of microgels in applications demanding dual pH/temperature specific drug delivery.

abstract: Thesis

abstract: Master of Applied Science (MASc)

abstract: Medications can exist in many different forms. From pills to injections, existing drug delivery systems require a high frequency of drug administration and often result in low efficacy of drug once administered to the human body. Polymer-based drug delivery systems have the potential to improve this delivery. In particular, microgels, water-filled crosslinked polymer networks with a size less than one micron, offer promise as a drug delivery vehicle. The size and chemical composition of microgels can be tailored to enable their use in a wide array of drug delivery applications. In addition, microgels can be loaded with a therapeutic agent and transported in the blood stream to deliver drug at a rate and/or location tunable based on the internal structure of the microgel. “Smart” microgels have the particularly attractive ability to change their properties in response to certain environmental stimuli (i.e. temperature or pH). However, current smart microgel systems are non-degradable and would accumulate in the body, causing undesired side-effects. In this thesis, a new self-assembly approach has been used to produce degradable microgels with the potential to switch properties in response to both temperature and pH. Water-insoluble drugs can be encapsulated more efficiently with this method, and the dual-responsive behaviour is expected to improve our capacity to deliver drug at the rate and location desired in the body.


title: The Effect of Fins on Fluidelastic Instability in In-Line and Rotated Square Tube Arrays

contributor:
Weaver, David
Mechanical Engineering

subject:
fin
fluidelastic
in-line
rotated square tube
tube array

abstract: The study of fluidelastic instability in tube arrays has been ongoing for four decades. Although much research has been conducted, a full understanding of the mechanisms involved is still not available. Designers of cross-flow heat exchangers must depend on experience and empirical data from laboratory studies. As new designs are developed, which differ from these experimental facilities, there is an increased risk of failure due to fluidelastic instability. An experimental program was conducted to examine fluidelastic instability in inline and rotated square finned tube arrays. Three arrays of each geometry type were studied; two with serrated, helically wound finned tubes of different fin densities, and the third, a bare tube which had the same base diameter as the finned tubes. The tube pitch was kept constant to reduce the number of test sections required under this investigation. As a result, the bare tube array has a larger tube pitch ratio than that of previous researchers. The finned tubes under consideration were commercial fmned tubes of a type typically used in the fossil and process industries. The addition of fins to tubes in heat exchangers enhances heat transfer due to the increased surface area and the turbulence produced by the flow moving over the fins. The resulting flow pattern/distribution due to the fins is therefore much more complicated than in bare tube arrays. Previous research has shown that an effective diameter of a finned tube is useful in the prediction of vortex shedding. This concept is used to compare the finned tube results with the existing bare tube array guidelines for fluidelastic instability. All of the tube arrays in the present study have the same tube pitch, and have been scaled to have the same mass ratio. Results for the rotated square arrays show that the use of an effective diameter is beneficial in the scaling of fluidelastic instability and the finned tube results are found to fit within the scatter of the existing data for fluidelastic instability. For in-line square arrays, the results indicate that fins significantly increase the stability threshold.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Integration of Dual-plane co-RASOR MR Imaging into Radiation Therapy Planning

contributor:
Noseworthy, Michael D
Biomedical Engineering

subject:
positive contrast
localization
gold fiducial markers
co-RASOR
image reconstruction
radial
magnetic resonance imaging

abstract:
Radiation therapy has a significant role in the management of cancer patients. Computed tomography (CT) has been at the forefront of radiation therapy planning due to its widespread diagnostic use and its electron density information. Magnetic resonance (MR) imaging is another proven diagnostic modality, which can achieve superior soft tissue contrast and margin delineation, relative to CT. As such it has become a valuable tool for cancer diagnoses and staging.

In this study, a centre-out radial acquisition using an off-resonance reception (co-RASOR) MR sequence, sensitive to magnetic field inhomogeneity, was applied to excite a broader frequency range of spins in the vicinity of metallic seeds. The resultant images display local hyperintensities around metallic markers. These images were then reconstructed with frequency offsets to rewind these hyperintensities to the geometric centre to obtain positive contrast.

The contrast-to-noise ratio (CNR) was measured between a fiducial and its surrounding to compare Fourier and iterative reconstruction methods for undersampled co-RASOR. The motivation was to reduce the sequence acquisition time, while preserving sufficient CNR and resolution. For single slices, acquisition was 2.8 sec and multi-slice acquisition could acquire more than 50 slices in 73 sec, by reducing the acquired data by a factor of 8. This effectively encodes acquisition to 1.4 sec/slice. The noise present in undersampled images decreased significantly using iterative reconstruction methods, but a total variation based penalty better preserved the edges.

Further extensions to the reconstruction method applied frequency-based filters that could isolate signals from different metallic compounds. The local hyperintensities rewind using opposite signed frequency offsets for diamagnetic and paramagnetic seeds. This allowed individual visualization of a low dose rate (LDR) brachytherapy seed and a gold fiducial marker. Phantom validation showed that each seed contains its maximal CNR in opposing frequency regions. The relative difference between global and local maxima in each frequency band ranged from 1.19 -- 3.73, and a single cut-off frequency was successfully applied for each acquisition plane.

Image guidance systems rely on the position of these fiducial markers to compare daily setup images with CT and MR simulations. Phantom experiments and porcine tissue samples were used to assess the minimum separation of fiducials, geometric accuracy, and random errors associated with using the co-RASOR sequence. co-RASOR images were able to resolve fiducials separated by 0.5 - 1 cm, depending on image resolution. No systematic biases were observed by comparing co-RASOR to CT using rigid body registrations. The standard deviation of the systematic errors were \textless 0.5 mm between MR and CT registrations, and \textless 0.4 mm between MR scans without CT. These values are smaller than the current total systematic uncertainties, which should be limimed to <3 mm.

The methods presented here can aid in understanding the trade-offs between acquisition speed and signal properties, differentiating cases where brachytherapy seeds are used in combination with fiducial markers for external beam boost, and aid in co-registration of multimodality imaging.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Development and Feasibility Testing of an Interprofessional Education to Support Collaborative Practice in Home Care for Older Adult Stroke Survivors with Multiple Chronic Conditions and their Family Caregivers

contributor:
Markle-Reid, Maureen
Nursing

subject:
interprofessional education
collaborative practice
community-based stroke rehabilitation
home care
older adults
effectiveness
feasibility

abstract:
Background. Many older stroke survivors live with multiple (> 2) chronic conditions (MCC), resulting in the need for care by multiple health and social service providers from multiple organizations and sectors. Managing the physical, social and psychological needs related to stroke in addition to other chronic conditions is a complex process that is best served by an interprofessional team of health care providers working collaboratively toward common goals. Interprofessional education (IPE) has been promoted by numerous organizations as a method to enhance collaborative practice. However, many home care providers have not received formal IPE or training to support collaborative practice. Providing IPE in the home care setting is challenging because providers rarely work in a common location, often work in isolation, and spend much of their time driving to provide care to clients in their homes.  Moreover, the effectiveness of IPE on collaborative practice for stroke rehabilitation in the home care setting is undetermined. New approaches to IPE for practicing health care providers working in the home care setting are needed. The purpose of this study was to examine the feasibility and acceptability of implementing a new theory-based, IPE intervention, and to explore its effects on collaborative practice in home care for older adult stroke survivors with MCC.
Method. This feasibility study involved the use of both a qualitative descriptive and a quantitative (one-group repeated measures) design. The IPE intervention was developed and evaluated within the context of a larger pragmatic randomized controlled trial (RCT), which evaluated the effectiveness of the Aging Community and Health Research Unit Community Partnership Program (ACHRU-CPP). Informed by the W(e) Learn Framework for Interprofessional Education, the National Interprofessional Competency framework, and the literature, the IPE intervention consisted of four key components: (a) an initial three-hour standardized IPE training session; (b) standardized training for care coordinators; (c) collaborative practice reflective huddles; and (d) outreach visits. The primary outcome was the feasibility of the IPE intervention (enrollment rate, attrition rate, implementation barriers/facilitators). Secondary outcomes included the acceptability of the IPE intervention, the feasibility of the study methods (recruitment/retention rates and procedures, eligibility criteria, data collection and analysis methods), and potential effectiveness of the intervention based on three-month changes in collaborative practice, as measured by the Collaborative Practice Assessment Tool (CPAT) and the 19-Item Team Climate Inventory (TCI). Feasibility and acceptability outcomes were based on descriptive statistics for enrollment and attrition rate and qualitative descriptive analysis of focus group content, field notes, and evaluation of training. The potential effectiveness of the IPE intervention was explored using paired t-tests and Cohen’s d, with the results expressed using descriptive statistics and effect estimates (95% confidence intervals).
Results. A total of 37 home care providers from two provider agencies and one Community Care Access Centre (CCAC) in Ontario, Canada participated in the study. Participants included registered nurses, physiotherapists, occupational therapists, personal support workers, care coordinators as well as nursing, rehabilitation and personal support worker supervisors. Participants viewed the intervention as feasible and acceptable. It was effective in improving three domains of collaborative practice as measured by the CPAT (communication/information exchange; community linkage and coordination of care; decision-making and conflict management) and one domain of collaborative practice, as measured by the TCI (task orientation) at six months post initial training.  Participants perceived many benefits to the intervention, including improved communication and collaboration within their teams, enhanced role understanding, increased learning with and from each other, and increased appreciation and valuing of the expertise of all team members. Facilitators to implementing the intervention included: funding from the larger trial, support from key stakeholders including agency leadership, provision of key resources (e.g., Team Charter, sample agenda), and continuity of the care coordinators. Barriers included unanticipated delays in recruitment of older adult stroke survivor participants into the larger trial, and higher than expected attrition rates. The study methods were feasible and effective in reaching the target population. We established that the intervention could be delivered as planned.
Conclusion. The results of this study provide preliminary evidence for the feasibility, acceptability and preliminary effects of the IPE intervention on collaborative practice for an interprofessional stroke-specific team in home care caring for older adult stroke survivors with MCC. The results also provide knowledge of the facilitators and barriers to successfully implementing and sustaining the intervention into home care practice. Further research is warranted to test this intervention in other chronic populations and settings.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: This feasibility study used qualitative and quantitative methods to evaluate the implementation of a new theory-based, Interprofessional Education (IPE) intervention and explored its effects on collaborative practice in home care for older stroke survivors with multiple chronic conditions. The IPE intervention was developed and evaluated within the context of a larger pragmatic randomized controlled trial (RCT), which evaluated the effectiveness of the Aging Community and Health Research Unit Community Partnership Program. The six-month IPE intervention consisted of four key components: (a) an initial three-hour standardized IPE training session; (b) standardized training for care coordinators; (c) collaborative practice reflective huddles; and (d) outreach visits. Participants included 37 home care providers including registered nurses, physiotherapists, occupational therapists, personal support workers, care coordinators, and nursing, rehabilitation and personal support worker supervisors from two service provider agencies and one Community Care Access Centre (CCAC) in Ontario, Canada. The intervention was effective in improving collaborative practice (e.g., communication within teams, role understanding, team decision-making and conflict management). Facilitators to implementing the intervention included: funding from the larger trial, leadership support, provision of key resources, and continuity of the care coordinators. Barriers included unanticipated delays in recruitment of older adult stroke survivor participants into the larger trial, and higher than expected attrition rates. This study offers preliminary evidence that the intervention is feasible to deliver, acceptable to providers, and may improve collaboration within an interprofessional stroke-specific team. Further research is necessary to test this intervention in other chronic populations and settings.


title: Representations of Social Media in Popular Discourse

contributor:
York, Lorraine
English and Cultural Studies

subject:
social media
discourse
popular culture
celebrity
Twitter
Facebook

abstract: This sandwich thesis of works published from 2010 – 2017 takes up the discursive articulation of “social media” as a mobilizing concept in relation to a variety of other concerns: authorship and popular fiction, writing and publishing, archives and everyday life, celebrity and the opaque morality of media promotion. The project addresses social networking platforms (primarily Twitter and Facebook) and those who serve and critique their interests (authors, readers, academics, “everyday people,” national archives, celebrities and filmmakers), often focusing on the “meta” of the media they take as their focus: extratexts, reviews and interviews, tweets about books and books about tweets, critical reception, etc. It considers “social media” as an idea or, more accurately, a system or constellation of ideas, a discourse or discourses beyond the mere technological. It examines the authority and impact of these discourses—not the use or usefulness of social media, but the ways these media are taken up, avoided, buttressed and manipulated in the most casual to the most politically contingent venues. In order to better comprehend and articulate the ideas, investments and ideological frameworks grounding social media discourse, this collective work traces and critically assesses the comparisons we make in an effort to render these media familiar and readable; the genealogies we construct in an effort to contextualize them and make their meanings legible; the stories we tell and the venues in which we tell them, to harness their creation and existence for other means, to authorize and deauthorize, to empower and disavow. By examining writing on and about social media, this work offers an alternative, context-specific approach to new media scholarship that, in its examination of things said and unsaid, will help inform our contemporary understanding of social media and, by extension, our social media experience.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: This sandwich thesis of works published from 2010 – 2017 considers how we talk and write about social media in relation to a variety of other concerns: authorship and popular fiction, writing and publishing, archives and everyday life, celebrity and the opaque morality of media promotion. The project addresses social networking platforms (primarily Twitter and Facebook) and those who serve and critique their interests (authors, readers, academics, “everyday people,” national archives, celebrities and filmmakers), often focusing on the “meta” of the media they take as their focus: “extratexts,” reviews and interviews, tweets about books and books about tweets, critical reception, etc. By examining writing on and about social media, this work offers an alternative, context-specific approach to new media scholarship that, in its examination of things said and unsaid, will help inform our contemporary understanding of social media and, by extension, our social media experience.


title: HEV Energy Management Considering Diesel Engine Fueling Control and Air Path Transients

contributor:
Yan, Fengjun
Mechanical Engineering

subject:
hybrid electric vehicle
energy management
diesel engine
fueling control
air path dynamics
model predictive control

abstract: This thesis mainly focuses on parallel hybrid electric vehicle energy management problems considering fueling control and air path dynamics of a diesel engine. It aims to explore the concealed fuel-saving potentials in conventional energy management strategies, by employing detailed engine models. The contributions of this study lie on the following aspects: 1) Fueling control consists of fuel injection mass and timing control. By properly selecting combinations of fueling control variables and torque split ratio, engine efficiency is increased and the HEV fuel consumption is further reduced. 2) A transient engine model considering air path dynamics is applied to more accurately predict engine torque. A model predictive control based energy management strategy is developed and solved by dynamic programming. The fuel efficiency is improved, comparing the proposed strategy to those that ignore the engine transients. 3) A novel adaptive control-step learning model predictive control scheme is proposed and implemented in HEV energy management design. It reveals a trade-off between control accuracy and computational efficiency for the MPC based strategies, and demonstrates a good adaptability to the variation of driving cycle while maintaining low computational burden. 4) Two methods are presented to deal with the conjunction between consecutive functions in the piece-wise linearization for the energy management problem. One of them shows a fairly close performance with the original nonlinear method, but much less computing time.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Multiple Model Control for Teleoperation Under Time Delay

contributor:
Sirouspour, Shahin
Electrical and Computer Engineering

subject:
model
control
teleoperation
time delay

abstract:
Performance and stability of bilateral teleoperation control systems are adversely affected by variations in environment dynamics and time delay in communication channel. Prior relevant research in the literature has mainly yielded control algorithms that sacrifice performance in order to guarantee robust stability. In contrast, this thesis proposes methods to deal with these two main problems in order to maintain the stability without compromising performance. To handle changes in environment dynamics, a multiple model controller for teleoperation is introduced. It is assumed that the dynamics of the environment are governed by a model from a finite set of environment models at any given time with Markov chain switching between these models. The first-order generalized pseudo-Bayesian (GPB1) multi-model estimation technique is used to identify the effective model at each time step given the sensory observations. The control action is a weighted sum of mode-based control laws that are designed for each mode of operation. The second major problem in teleoperation systems that this thesis deals with is communication channel time delay. The constant time-delay problem is solved using two different methods, i.e. discrete-time and continuous-time predictive type Linear Quadratic Gaussian (LQG) controllers. The treatment of the problem in the discrete-time domain allows for the development of a finite dimension state-space model that explicitly encompasses the time delay. The robustness of the controller with respect to uncertainty in the system parameters is examined via Nyquist analysis. In continuous-time, a modified state transformation is proposed to obtain delay-free dynamics based on the original dynamics with delayed inputs and outputs. The application of the continuous-time LQG control synthesis to these reduced dynamics yields a control law that guarantees closed-loop stability and performance. Mode-based controllers are designed for each phase of operation, i.e. free motion/soft contact and contact with rigid environments. Performance objectives such as position tracking and tool impedance shaping for free motion/soft contact, as well as position and force tracking for contact with rigid environments are incorporated into the LQG control design framework.
Simulation and experimental results are presented for each of the proposed controllers in various scenarios. These results demonstrate the effectiveness of the proposed methods in providing a stable transparent interface for teleoperation in free motion and in contact with rigid environments.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: The Distribution and Ecological Significance of the Boring Sponge Cliona viridis on the Great Barrier Reef, Australia

title: Distribution and Ecological Significance of Cliona virdidis

contributor:
Risk, M. J.
Geology

subject:
ecological
distribution
boring sponge
cliona viridis
cliona
great barrier reef
australia

abstract: Production of fine sediments in reef environments is a poorly understood but probably significant process. On the Great Barrier Reef, Cliona viridis is locally abundant. The sponge has been found from Lizard Island in the north, down to the southern part of the Central Region, and it is likely even more widespread. Although on individual reefs the sponge may occur almost anywhere, it is most abundant on lagoon path reefs ("bommies" in Australian), where it overgrows the substrate and bores to a constant depth of about 1.3cm. Sponge infestation reaches a maximum at a depth of 4 m covering almost 8% of the vertical sides of bommies. It is frequently the dominant benthic organism. Serial underwater photography demonstrates that colonies can expand laterally at a rate of about 1 cm yr⁻¹ removing approximately 40% of the substrate. This species is a major producer of fine sediment on the Great Barrier Reef.

abstract: Thesis

abstract: Master of Science (MS)


title: Design and Simulation of Lithium Niobate Waveguides and Devices

contributor:
Huang, W. -P
Xu, C. Q.
Electrical and Computer Engineering

subject:
design
lithium niobate
waveguides
device

abstract: This thesis with the research development in design and modeling of the lithium niobate (LiNbO₃) optical waveguides. In particular, the material and modal properties of the titanium (Ti)-indiffusion and annealed proton-exchange (APE) are investigated thoroughly. By linking the relation of the design and fabrication parameters with modal properties of the LiNbO₃ waveguides, a comparative study on modaling and characterization of diffused optical waveguides is presented. First we investigate the diffusion, exchange, and annealing processes analytically and numerically. Through comparing different models of index change with concentration of the related species such as titanium and hydrogen, the material properties can be calculated. The accuracy and the scope of validity for the analytical methods are also investigated. Some important fabrication and design parameters are abstracted and used for calculating the index distribution of the optical waveguides. Then, by applying a rigorous finite difference method, the modal properties of the diffused waveguides, such as modal profile, effective index, and coupling loss with the standard fiber, can be calculated. The modal properties of the optical waveguides directly link to the fabrication parameters of corresponding waveguides. Based on modal properties of optimized waveguides, the device performances of the related devices can be easily obtained. Based on the analysis of general LiNbO₃ optical waveguides, the detail material and modal properties of the titanium-indiffusion and APE LiNbO₃ optical waveguides are further investigated. Their fabrication processes are reviewed and typical process parameters are given. Furthermore, by comparing with measurement results of the titanium-diffusion and APE LiNbO₃ optical waveguides made in McMaster University, the relation between the waveguide modal performance and design parameters is built through some effective methods and ready to be applied in the design of optical devices. Finally, we reconstruct the refractive index distribution of the optical waveguides by using the measurement results of modal properties.

abstract: Thesis

abstract: Master of Engineering (ME)


title: Characterization of EBNA1 Cooperative Interactions and EBNA1-Induced Origin DNA Distortion

title: Cooperative Assembly of EBNA1 and Induced DNA Distortion

contributor:
Frappier, Lori
Biochemistry

subject:
EBAN1
DNA
distortion
cooperative interaction

abstract: Epstein-Barr virus nuclear antigen 1 (EBNA1) is the only viral product needed for replication of the latent Epstein-Barr virus genome. The latent origin of replication, oriP, consists of two cis-acting elements, the family of repeats (FR) containing twenty EBNA1 recognition sites, and the dyad symmetry element (DS) containing four recognition sites. Bidirectional DNA replication is known to occur within or near the DS. Previous studies have suggested that EBAN1 binds cooperatively to its recognition sites in the DS and have shown that EBNA1 binding induces DNA distortion within site 1 and site 4 of the DS. I have used EBNA1 mutants in electrophoretic mobility shift assays, methylation protection footprinting, and potassium permanganate reactivity analysis to examine EBAN1 assembly on the DS and the requirements for DNA distortion. I have found that: 1) EBNA1 has a 10-11 fold higher affinity for the outer two sites of the DS than the inner two sites due to DNA sequence variation, 2) the minimum region of EBNA1 necessary for site specific binding is contained within amino acids (a. A.) 470-607 but a.a. 459-470 greatly affect binding affinity, 3) EBNA1 dimers bind cooperatively on adjacent binding sites and the region responsible for this interaction is also contained between a.a. 470-607. I have also shown that EBNA1 binding to a single DS site 1 recognition site is sufficient to induce DNA distortion within that site and this distortion can be caused by a truncation mutant spanning a.a. 463-607 but not a.a. 468-607. Finally, although wild type spacing between recognition sites of the DS is critical for replication it is not crucial for EBNA1 binding or EBNA1 induced DNA distortion.

abstract: Thesis

abstract: Master of Science (MS)


title: Developing a Genetic Linkage Map from an Intervarietal Cross of Serotypes A and D and the Analysis of the Costs and Benefits of Hybridization in Cryptococcus neoformans

title: Hybridation in Cryptococcus neoformans

contributor:
Xu, Jianping
Biology

subject:
genetic
linkage
map
serotype
benefit
hybridization
cryptococcus
cryptococcus neoformans

abstract:
Thesis
Master of Science (MS)


title: Early Stages of Ageing in Al-Mg-Si Alloys

contributor:
Zurob, Hatem
Materials Science and Engineering

subject: ageing Al-Mg-Si alloy

abstract: Natural ageing is known to have a negative effect on the formability and bake-hardening response of Al-Mg-Si alloys. This is attributed to the formation of Mg and Si clusters during natural ageing. The clustering process was the subject of many studies in the literature, however, the formation mechanism and kinetics of it, continues to be poorly understood. The aim of this project is to shed some light on the cluster formation mechanism and measure clustering kinetics at low temperatures. A series of electrical resistivity measurements, positron annihilation lifetime spectroscopy and hardness tests were performed on samples aged over the temperature range of -20 to 50°C following solution treatment at temperatures of 525 and 560°C. A very good correlation between the results of various techniques was observed. In addition, three different stages in the clustering process were detected. Not surprisingly it was found that the excess quenched-in vacancies are the key players in the cluster formation process. In the first stage, annihilation of near-sink vacancies occurs while other vacancies start to bind with solute atoms and form clusters. In the second stage, clustering continues to take place but its rate slows down since the effective diffusion coefficient of vacancies decreases as they bind with more solute. Finally, the clustering process enters the third stage with much slower kinetics. Interestingly, positron annihilation lifetime also reaches a constant value at the beginning of stage III which suggests the stabilization of vacancies. Two hypothesis were then developed to explain the existence of stage III: one based on the immobilization of vacancies due to the increased binding with solute atoms and another one which considers the overlapping of solute diffusion profiles around the clusters. Finally it was shown that the resistivity change in stage II can be used to find the activation energy of clustering which is calculated to be approximately 46 kJ/mol. This is very close to the migration energy of vacancies and Mg atoms. Thus it was concluded that migration of these species is the major rate controlling parameter for the clustering process.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Electrical Discharge Milling with Oblong Tools

contributor:
Fleisig, Robert
Koshy, Philip
Mechanical Engineering

subject: electrical discharge milling oblong tool

abstract: Electrical discharge machining (EDM) is perhaps the most prevalent non-traditional machining process in industry. Therefore, a great amount of effort has been invested towards improving the process. One result of these efforts was the introduction of CNC capabilities to EDM machine tools. Though CNC capabilities are predominantly used for performing orbital EDM, they may also be used for electrical discharge (ED) milling. Cylindrical tools are typically used in ED milling. While other tooling concepts have been developed for use with CNC EDM, this area of EDM is lacking in research. In this work an oblong set of tools for ED milling is presented. The set contains tools capable of machining cavities with both round and sharp features. Motivation for development of the tool set is discussed along with the benefits accompanied by the use of these tools. The cavity profiles considered in this work are divided into three groups based on concavity, continuity and geometric composition. Based on these groups, algorithms are presented for tool type selection and tool size calculation. Tool path planning strategies for each of the tool types are also presented. Two examples are presented in which the algorithms are applied to 2D profiles. The first of these profiles is star shaped, while the second is gear shaped. Both examples were machined on a 4-axis CNC EDM using the oblong tools presented in this work. When compared to equivalent cylindrical/square tools, the oblong tools used for the machining of the cavities provided a substantial increase in frontal area corresponding to improved material removal rates. Furthermore, for both examples, the complete machining of a single layer is accomplished with only one pass of the tool.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Salient Index for Similarity Search Over High Dimensional Vectors

contributor:
He, Wenbo
Computing and Software

subject:
approximate nearest neighbor
locality sensitive hashing
index structure
searching strategy

abstract: The approximate nearest neighbor(ANN) search over high dimensional data has become an unavoidable service for online applications. Fast and high-quality results of unknown queries are the largest challenge that most algorithms faced with. Locality Sensitive Hashing(LSH) is a well-known ANN search algorithm while suffers from inefficient index structure, poor accuracy in distributed scheme. The traditional index structures have most significant bits(MSB) problem, which is their indexing strategies have an implicit assumption that the bits from one direction in the hash value have higher priority. In this thesis, we propose a new content-based index called Random Draw Forest(RDF), which not only uses an adaptive tree structure by applying the dynamic length of compound hash functions to meet the different cardinality of data, but also applies the shuffling permutations to solve the MSB problem in the traditional LSH-based index. To raise the accuracy in the distributed scheme, we design a variable steps lookup strategy to search the multiple step sub-indexes which are most likely to hold the mistakenly partitioned similar objects. By analyzing the index, we show that RDF has a higher probability to retrieve the similar objects compare to the original index structure. In the experiment, we first learn the performance of different hash functions, then we show the effect of parameters in RDF and the performance of RDF compared with other LSH-based methods to meet the ANN search.

abstract: Thesis

abstract: Master of Science (MSc)


title: A Study on the Expression of Estrogen-Responsive Genes in Rainbow Trout, Salmo gairdneri

contributor:
Chen, T. T.
Biology

subject:
expression
estrogen
gene
rainbow trout
salmo gairdneri
salmo

abstract:
The expression of the estradiol-responsive genes in the liver of rainbow trout, Salmo gairdnerii, has been studied as a system which may permit quantitative measure of adverse sublethal effects of various xenobiotics. Upon administration of 17 β-estradiol to male or immature female rainbow trout, the expression of two genes are markedly enhanced. One of these genes codes for the egg yolk precursor protein, vitellogenin, whereas the other codes for another, as yet unidentified, protein. Complementary DNA (cDNA) genes of these two proteins have been employed as probes to characterize the dose-response relationship as well as the time course induction of these two classes of transcripts in liver both in vivo and in vitro. The maximal net transcription of pRTC 2 occurs at 20 ug β -estradiol per 100 gram fish body weight whereas those encoded for by pRTC 5 display maximal transcription at 5 μg β-estradiol per 100 gram fish body weight. With doses exceeding the dose required for maximal induction of transcripts, both classes of transcripts reach their maximal levels between 4 and 8 hours after primary and secondary induction. Transcripts homologous to pRTC 5 return to control levels by 16 hours and 2 days after primary and secondary induction respectively. Those homologous to pRTC 2 however, were not observed to recover to normal levels in the primary induction even 16 days after stimulation with estradiol. However, upon secondary induction pRTC 2 transcripts returned to control levels 8 days post-inoculation with estradiol. The effect of various xenobiotics on the induction of these two estradiol-responsive genes was investigated. Pretreatment with β-naphthoflavone resulted in neither the induction or repression of both classes of transcripts. Administration of Kepone prior to a subsequent stimulation with estradiol, resulted in a decrease in the accumulation of pRTC 2 transcripts only. In contrast, an isomer of DDT, p,p'-DDT, was found to enhance the expression of pRTC 5 transcripts in fish subsequently administered β-estradiol. Oncogenes have been found to be activated in transformed cells or cells treated with various xenobiotics. In this study, I have shown that the cellular oncogene, pRTC-myc 1-81, is expressed in the liver at an elevated level in response to estradiol treatment. The two classes of polyadenylated transcripts were detected (2.5 kb and 5.6 kb). The three estradiol-responsive genes mentioned above (pRTC 2, pRTC 5, and pRTC-myc 1-81) were also shown to be transcribed in an established rainbow trout hepatoma cell line. Transcriptional activities of all three genes, as well as the translational activity of vitellogenin, were diminished upon growth in serum stripped of endogenous hormones.
Further characterization of this rainbow trout hepatoma cell line is warranted so that it may be employed in a sensitive and quantitative bioassay for assessing the pathobiochemical effects of environmental xenobiotics on fish reproduction. Such an index may be beneficial for establishing adequate guidelines for water contaminants that potentially could affect aquatic and human reproductive success.

abstract: Thesis

abstract: Master of Science (MS)


title: ETHICAL DECISION-MAKING IN OCCUPATIONAL THERAPY PRACTICE IN CANADA

contributor:
Moll, Sandra
Rehabilitation Science

subject:
ethical decision-making
occupational therapy practice
clinical reasoning
ethics education
professional practice
mentorship
on-line education
clinician-educators

abstract: Introduction: Ethical decision-making is an important component of occupational therapy practice in Canada. Research is needed to understand ethical decision-making and how to build occupational therapists’ competency to make ethical decisions. Purpose: The aim of this thesis was to study ethical decision-making in occupational therapy practice in order to contribute to epistemological development regarding ethics in occupational therapy and to support continuing competency in ethical decision-making. Method: Three studies comprise this thesis. A constructivist grounded theory study was conducted involving in-depth semi-structured interviews with 18 occupational therapists from a range of practice settings to explore the process of ethical decision-making. An interpretive description study using secondary analysis of grounded theory data was conducted to explore gaps related to continuing competency in ethical decision-making from the participants’ perspective and to generate recommendations for future directions to support continuing competency. Finally, a non-randomized, single-group, pre- and post-test study (n=33) was conducted to evaluate an on-line education module developed to support competency for clinician-educators. Findings: The grounded theory study led to development of an ethical decision-making prism capturing three processes: Considering the Fundamental Checklist, Consulting Others, and Doing What’s Right. The interpretive description study highlighted two gaps related to continuing competency in ethical decision-making: lack of knowledge and lack of supports. Education, tool development, and ethics mentorship were identified directions for development. The third evaluation study found that an on-line education module led to improvements in ethics knowledge and intent to change practice but not to actual practice change. Implications: This thesis advances a theoretical understanding of ethical decision-making in occupational therapy practice and an applied understanding of occupational therapists’ needs related to competent ethical decision-making. Findings also provide preliminary data regarding on-line ethics education to advance knowledge and skills of clinician-educators who are involved in cultivating ethical decision-making among student occupational therapists.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: “Doing what’s right”, or ethical decision-making, is an important part of being an occupational therapist in Canada. To help occupational therapists build knowledge and skills it is important to understand how they make ethical decisions in day-to-day practice. This PhD describes three studies that look at three different aspects of ethical decision-making. The first study presents a theoretical explanation of how occupational therapists decide what’s right to do. The second study uses the same data to look at supports that occupational therapists feel they need to build knowledge and skills about ethical decision-making. The third study measures the value of an on-line education course in helping occupational therapy educators teach students about ethical decision-making. Results of these studies can be used to support occupational therapists in doing what’s right. Results also highlight areas for additional study to further support ethical occupational therapy practice in Canada.


title: Changes in Electrical Properties and Ooplasmic Activities of Na⁺, K⁺, H⁺, Ca⁺⁺, and Cl⁻ During Egg Development in the Locust

title: Electrical Properties, pH, and Ion Activities in Locust Eggs

contributor:
O'Donnell, M. J.
Biology

subject:
electrical properties
ooplasm
sodium
potassium
chlorine
calcium
hydrogen
locust
egg

abstract: This thesis addresses two hypotheses: 1) ooplasmic ion activity is regulated during water uptake by locust eggs, and, 2) activities of Ca⁺⁺ and H⁺ are maintained at levels appropriate for their use as signals for developmental processes, including activation, in insect eggs. Hypothesis 1 is based on the perturbing effect of large changes in intracellular Na and/or K activity on enzyme function in eukaryotic cells. Hypothesis 2 is based on the ionic hypothesis of activation developed from studies of eggs of marine invertebrates. Electrical potential difference across egg membranes (PD_egg), and ooplasmic activities of Na⁺, K⁺, Cl⁻, Ca⁺⁺ and H⁺ were measured with double-barrelled ion-selective microelectrodes. Locust eggs maintained a measurable potential difference across egg membranes throughout development. Input resistance (Rᵢₙ) decreased by approximately 5-fold in eggs after fertilization suggesting that the chorion is not the major barrier to ion movements into and out from the egg. Chilling and anoxia decreased the contribution of a metabolic component to PD_egg. The effects of hypercapnia on PD_egg and ooplasmic pH suggest that the metabolic component may be a H⁺-pump. Chloride diffusion contributes to PD_egg in eggs after fertilization; contributions of other ions were relatively small. Potential differences measured in internally perfused locust eggs after osmotic lysis of the serosal epithelium indicated that the chloride-dependent component of PD_egg is developed across the chorion and/or serosal cuticle. In vivo values of PD_egg are probably less negative than values measured in control saline because chloride content of ground water is low. Ooplasmic sodium and potassium activities remained at typically intracellular levels during water uptake, possibly due to release from internal stores. Chloride activities were typical of extracellular fluids and were not regulated during water uptake. Measurements of pH and pea in locust eggs are consistent with the increases in these parameters predicted by the ionic hypothesis of activation. calcium activity in the ooplasm of unfertilized locust eggs (pCa 6.4 -4.9) appeared to be at a level appropriate for the use of calcium as a signal or second messenger. Calcium activity increased 100fold within 1 day of fertilization, and 1000-fold by day 3. Calcium entry from external sources at fertilization and release from internal stores later in development may contribute to the progressive increase in ooplasmic Ca⁺⁺ activity. The ooplasm likely alkalinizes after oviposition as ambient pCo₂ declines. Available data suggest a metabolically-dependent proton pump may control ooplasmic pH in locust eggs, in contrast to the Na⁺/H⁺ exchanger implicated in alkalinization of marine invertebrate eggs.

abstract: Thesis

abstract: Master of Science (MS)


title: An Investigation of Stable Carbon and Nitrogen Isotope Analysis Throughout the Life of Small Mouth Bass: Implications for Trophic Level Studies

title: δ¹³C and δ¹⁵N within the Lifecycle of Smallmouth Bass

contributor:
Schwarcz, Henry
Geology

subject:
carbon
nitrogen
isotope
small mouth bass
bass
trophic level

abstract: In this study ¹³C/¹²C and ¹⁵N/¹⁴N ratios were measured from 𝘔𝘪𝘤𝘳𝘰𝘱𝘵𝘦𝘳𝘶𝘴 𝘥𝘰𝘭𝘰𝘮𝘪𝘦𝘶 tissue, from all stages throughout the fish's lifecycle. The different stages in the life of 𝘔𝘪𝘤𝘳𝘰𝘱𝘵𝘦𝘳𝘶𝘴 𝘥𝘰𝘭𝘰𝘮𝘪𝘦𝘶 are represented also by shifts in the trophic level of the fish. As embryos, the δ¹⁵N and δ¹³C values for 𝘔𝘪𝘤𝘳𝘰𝘱𝘵𝘦𝘳𝘶𝘴 𝘥𝘰𝘭𝘰𝘮𝘪𝘦𝘶 tissues are dependent on the δ¹⁵N and δ¹³C of the mother. Also until the point of metamorphosis, where the yolk sac is completely used up, the isotopes reflected in the tissues represent a combination of the δ¹⁵N and δ¹³C of the yolk and any plankton which the young fish are able to feed on. As the fish grows and its diet changes to crayfish and other smaller fish the isotopes reflected in the 𝘔𝘪𝘤𝘳𝘰𝘱𝘵𝘦𝘳𝘶𝘴 𝘥𝘰𝘭𝘰𝘮𝘪𝘦𝘶 shift as the fish effectively increases its trophic position. Definite trends were seen in the δ¹⁵N values throughout the entire lifecycle of 𝘔𝘪𝘤𝘳𝘰𝘱𝘵𝘦𝘳𝘶𝘴 𝘥𝘰𝘭𝘰𝘮𝘪𝘦𝘶, and while the δ¹³C values did not produce such definite trends it was discovered that there was an overlying spatial trend represented in the δ¹³C values. This means that Micropterus dolomieu of similar age and size display an obvious offset in their δ¹³C values depending on their location in the lake. Also addressed here are the potential problems related to working with preservative chemicals and the effects they have on isotope ratios. Shifts were not only seen in both δ¹⁵N and δ¹³C (as has been addressed in the past) but also between different batches of the same preservative fluid. Different batches of formalin can potentially give different offsets to both δ¹⁵N and δ¹³C, making it necessary to calibrate offsets given by all batches of formalin used throughout the entire procedure.

abstract: Thesis

abstract: Master of Science (MS)


title: Effect of Growth Horomone on Rainbow Trout: An Ecological Assessment of the Potential Impact of Genetic Engineering on Organism Design

title: An Ecological Assessment of Genetic Engineering

contributor:
Rollo, C. D.
Biology

subject:
growth
hormone
rainbow trout
trout
genetics
engineering
impact
organism

abstract: Trout genetically engineered to possess extra functioning growth homone genes were simulated, using injections of fish and bovine growth hormone. This was done to test potential and ecological impact of such genetic engineering on trout. Through analysis of growth and dry-mass budgets, it was determined that elevated levels of growth hormone resulted in increased growth and consumption. Potential constraints pertaining to respiration, density and evolutionary history were considered. Surprisingly, bovine growth hormone appeared to act as a super-normal stimuli, being more potent than the natural trout hormone. In fact the natural hormone inhibited growth at high dosages. Juvenile growth rates were less sensitive to elevated levels of growth hormone than those in more mature fish. Thus, improved growth was achieved by altering its normal ontogeny. This suggests that duplicating copies of growth hormone gene in an organism is not equivalent to a speciation event. Evidently, other manipulations would be required to increase the intrinsic metabolic power. Growth rate apparently is used as a cue for determining a particular ontogenetic trajectory (Stearns and Crandall, 1984). The fact that various species conform to one of at least four plastic developmental trajectories that are shaped by natural constraints and mortality patterns, means that growth hormone may elicit different responses in different species. The findings and implications of this study underscore the importance of using the holistic scope of ecology to achieve effective and efficient genetic engineering of target species.

abstract: Thesis

abstract: Master of Science (MS)


title: Factors Contributing to Dry Weight Differences Among Herbivorous Zooplankton in Two Softwater Lakes

subject: weight herbivore zooplankton softwater lake

abstract:
The dry weight of zooplankton is an important parameter conventionally used to estimate secondary production in aquatic ecosystems. Estimates of zooplankton weight vary considerably across studies. This study examines various factors that contribute to differences in the individual dry weight of freshwater herbivorous zooplankton. In the first chapter, I quantified and compared the individual length and weight changes of Daphnia catawba and Diaptomus minutus resulting from preservation in either 4% sugar-formalin, 70% ethanol solution or freezing over dry ice. The results indicate that the dry weight of both animals was significantly altered by chemical preservatives. The length of Diaptomus was also significantly reduced due to preservation. Site-specific differences in lakes, such as available food and the presence of predators, introduce another potential source of variation in herbivore dry weight. In Chapter 2, the food available to several herbivorous zooplankton in two softwater lakes was estimated using various methods. An index of "edible" phytoplankton biomass based on stomach content analyses was developed and compared to the traditional techniques used to estimate available food. The results indicate that the available was food different for each herbivore and that estimates of food available based on stomach content analyses were not significantly related to the
traditional techniques used to estimate available food. In Chapter 3, I evaluate the relative impacts of "topdown" (predation) versus "bottom-up" (food) effects on the dry weight of several herbivores in two softwater lakes with contrasting food-web structures. The length-specific dry weights of Daphnia catawba, Diaptomus minutus and Holopedium gibberum varied seasonally and these changes were taxa-specific and unique to each lake. Herbivore weights were regressed against length, available food, clutch size, population density and temperature to determine if "bottom-up" effects could explain between-lake differences in herbivore weight. Length and population density were the prominent predictor variables in the resulting regression models for the herbivores in these lakes. Predator effects were determined by comparing if the between-lake differences in herbivore weight were consistent with the presence or absence of planktivores. Holopedium dry weight was lower in the presence of planktivores, while Diaptomus dry-weight differences exhibited no consistent trend with the presence or absence of planktivores.

abstract: Thesis

abstract: Master of Science (MS)


title: Analysis of SSS1P: An Essential Tail-Anchor Protein of the ER Translocon in the Yeast Saccharomyces cerevisiae

title: Analysis of SSS1P: An Essential Tail-Anchor Protein in Yeast

contributor:
Andrews, David
Biochemistry

subject:
Sss1p
ER
translocon
yeast
saccharomyces cerevisiae
saccharomyces

abstract: Sss1p is an essential component, along with Sec61p, of the protein conducting channel (PCC) in the ER of the yeast Saccharomyces cerevisiae. It belongs to a family of proteins termed tail-anchor (TA) proteins. The TA consists of a single hydrophobic sequence at the carboxyl-terminus which anchors the protein to the membrane in a Type II (N_cytoplasm-C_lumen) orientation. TA proteins are targeted to their membranes of function through an uncharacterized SRP-independent, post-translational mechanism. The targeting mechanism and function of Sss1p are not known. In this thesis, results will be presented from targeting and functional studies of Sss1p. Sss1p is predicted to contain an ER targeting signal similar to mammalian VAMP-1A. Disruption of this putative signal caused incomplete mislocalization of Sss1p to the mitochondria which did not affect yeast growth. Mutations in the TA of Sss1p had numerous effects. Yeast expressing these mutants showed diminished growth, a defect in co-and post-translational translocation, inefficient ribosome binding to Sec61 p and the mislocalization of translocon components from light membranes (predominantly ER) to heavy membranes (predominantly mitochondria). It is argued that mutations in the TA of Sss1p disrupt the function of the protein, subsequently leading to the general defects listed above. Two possible functions for Sss1p are proposed: Sss1p is involved in forming the signal sequence binding pocket of the translocon and/or is essential for the integrity of the PCC.

abstract: Thesis

abstract: Master of Science (MS)


title: Influence of Ni(II)-Binding Ligands on the Cellular Uptake and Distribution of Ni^2+

title: Chelating Agents and Cellular Association of Ni^2+

contributor:
Nieboer, Evert
Biochemistry

subject: nickel ligand cellular distribute uptake influence

abstract: The effect on Ni^2+ uptake of human serum albumin (HSA), sodium diethyldithiocarbamate (DOC), D-penicillamine (O-Pen) , ethylenediaminetetra-acetic acid [di sodiurn salt] (EDTA) , L-aspartic acid (L-Asp) , L-Lysine (L-Lys) , and L-histidine (L-His) was examined in three cell lines: (1) human red blood cells (RBCs), (2) cultured human B-lymphoblasts and (3) rabbit alveolar macrophages. It was found that EDTA, L-His, HSA, and O-Pen were good inhibitors of ^63Ni^2+ uptake by cells and each was able to remove ^63Ni^2+ previously associated with the cells. In contrast L-Lys and L-Asp, which do not bind Ni^2+ well, were both poor inhibitors of Ni uptake and poor sequestering agents for cell-associated Ni^2 +. Thus it seems that at physiological concentrations , L-His and HSA play a major role in regulating the association of Ni^2+ with cells. DOC enhanced cellular uptake of ^63Ni^2+, but was not very effective in removing ^63Ni^2+ from cells. An increase in pH enhanced ^63Ni^2+ uptake in the lymphoblasts, macrophages and human peripheral lymphocytes. This dependence was interpreted to indicate the existence of either: (1) an increase in membrane permeability with an increase in pH; (2) the development of a proton gradient across the cell membrane favouring the antiport transport of H^+ and Ni^2+; or (3) Ni^2+;proton competition for cellular binding groups. The cellular uptake of Ni^2+ is interpreted in terms of an "equilbrium" model of metal-ion transport. It is concluded that since HSA and L-His can control cellular uptake and removal of Ni^2+, they may play a role in regulating the cellular toxicity of this ion. It was found that L-His and O-Pen acted similarly such that at various concentrations both inhibited cellular uptake of ^63Ni^2+ but did not change the normal distribution of Ni^2+ within the cell. Conversely, DOC enhanced Ni^2+ uptake by cells while simultaneously shifting the distribution of Ni^2+ from the cell lysate to the cellular membranous pellet. Furthermore, DOC caused Ni^2+ to become more lipophilic as shown by the increase of ^63Ni^2+ in a chloroform extract. DOC also caused a change in Ni^2+ distribution in whole blood by enhancing Ni^2+ association with RBCs and lymphocytes and decreasing serum-associated Ni^2+. The different responses produced by O-Pen, L-His and DOC are ascribed to the hydrophilicity of the [Ni(D-Pen)_2]^2- and Ni(His)_2 complexes and the lipophilicity of the Ni(DDC)_2 complex, and allow a rationalization of the contrasting therapeutic effects of O-Pen and DDC.

abstract: Thesis

abstract: Master of Science (MS)


title: A Computerized Hybrid RF-Waterbath Heater for Mouse Tumors

contributor:
Kwok, Cheuk
Health and Radiation Physics

subject: computer hybrid waterbath mouse heater tumor

abstract: A computer-controlled system, based on the design of S. Brown et al. at the Ontario Cancer Institute, Canada, has been developed for uniform heating of mouse tumors. A steady hyperthermic temperature was maintained in the tumor by combining waterbath heating with RF-heating. The RF field was provided by a transmitter which was connected to two steel capacitive plates via a matching circuit. 50% isotonic saline kept at a temperature 2°C below that in the tumor was circulated in the waterbath. The saline prevented overheating of the skin and provided coupling between the RF field and the tumor. A computer program has been written to measure continually the temperature in the tumor with implanted fine thermocouples. The program also controlled the average RF power delivered to the tumor by switching the transmitter on and off at appropriate intervals. The system has been tested on tumor xenografts growing in the thigh of nude mice. A steady temperature of 42° or 44°c has been maintained in the tumor for up to an hour. The system could be used to study the effect of hyperthermia on the uptake of radiolabelled tumor-associated antibodies and the treatment of tumors by such antibodies.

abstract: Thesis

abstract: Master of Science (MS)


title: Improved Receiver Characterization and Source Selection Technique for Microwave-Frequency Noise Measurement

contributor:
Chen, Chih-Hung
Bakr, Mohamed
Electrical and Computer Engineering

subject: microwave microwave-frequency noise technique receiver source

abstract: An accurate noise measurement is essential to a proper characterization of a noisy device. In the 1950s, the IRE first proposed the classical noise parameters for characterizing a noisy linear two-port network, and subsequently a measurement and extraction procedure. Since then, the task of accurately characterizing the parameters has always been challenging due to the sensitive nature of the noise parameters. This is especially so for an on-wafer device noise measurement, as opposed to that of a packaged device, due to various factors such as the lower noise level and losses in the signal path. Combined with the downscaling of the MOSFET technology in recent decades, which also improved the device's noise performance, they make noise measurement and characterization become even more difficult. A typical noise measurement starts with the calibration or characterization of the measurement system. This step is as important as the measurement itself in terms of the ultimate accuracy of the results. This thesis presents a noise receiver characterization method which improves upon existing methods by accurately taking into account the different reflection coefficient of the noise source between its hot and cold states. The improvement allows more precise determination of the receiver characterizations. Numerous studies have investigated the effect of the choice of the source terminations on the noise measurement results. These studies often provided contradicting suggestions on the selection techniques. In the thesis, a selection technique is proposed that allows quick determination of desirable terminations. Analyses using real measurement data on a 65 nm n-type MOSFET show that the proposed technique is able to provide terminations that yield noise parameters with smaller uncertainties relative to other terminations.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Effects of Waste Glass Addition on the Properties of Fired Clay Brick

contributor:
Chidiac, Samir
Civil Engineering

subject:
glass
fired clay
clay brick
waste glass

abstract: The optimization of the production of fired clay brick is essential in order to maintain a sustainable industry in Ontario. While there exists areas for improvement of the properties of bricks used in severe climates, concerns including non-renewable resource depletion, increasing energy costs, and waste management have become increasingly important in Canadian and global industries. One method to address these concerns is the use of waste additives as fluxing agents in bricks. While a fluxing agent reduces the firing temperature required for sintering of the brick and improves properties, the use of a waste additive can decrease the dependency of the industry or non-renewable resources such as mined clay or crushed shale. Waste additives can improve strength durability, and absorptive properties, while decreasing firing temperature, and diverting waste from landfills. A testing program was developed to determine the effects of several variables in brick production, including extrusion and firing, and to investigate the effect of the addition of non-recycled waste glass in the properties of fired clay brick. The addition was varied in the particle size of the waste glass and the percentage by mass of additive. The effects of waste glass addition were determined in terms of absorption, strength, and freeze-thaw durability of the individual specimens. Microstructure was also investigated using SEM images and mercury intrusion porosimetry to determine the effect on pore structure and vitrified matrix of the bricks. The results of the testing program determined an optimal addition of waste glass, and the expected effects of the implementation of this addition to the production of fired clay brick in an industrial setting.

abstract: Thesis

abstract: Master of Applied Science (MASc)