title: Functional characterization of asymmetric cell division associated genes in hematopoietic stem cells and bone marrow failure syndromes

contributor:
Hope, Kristin
Biochemistry and Biomedical Sciences

subject:
Hematopoietic stem cell
Bone marrow failure
Asymmetric cell division
Arhgef2
Staufen1
Shwachman-Diamond syndrome
Aplastic anemia
Paroxysmal nocturnal hemoglobinuria
RNA-binding protein

abstract: Hematopoietic stem cells (HSCs) are critical to the development of the hematopoietic system during ontogeny and maintaining hematopoiesis under steady-state.  Several genes implicated in asymmetric cell division (ACD) have been found to influence HSC self-renewal in normal hematopoiesis and various leukemias.  From a separate survey of genes associated with ACD, I now present the results from dedicated functional studies on two genes – Arhgef2 and Staufen1 – in HSCs and identify their potential contributions to benign hematopoietic disorders.  Specifically, I present evidence that demonstrates a conserved role of Arhgef2 in orienting HSC division, the loss of which leads to HSC exhaustion that may underlie and contribute to the pathogenesis of Shwachman-Diamond syndrome.  I also identify Staufen1 as a critical RNA-binding protein (RBP) in HSC function, downregulation of which elicits expression signatures consistent with clinical anemias reminiscent of aplastic anemia and/or paroxysmal nocturnal hemoglobinuria.  I end by reviewing how RBPs function in HSCs and discuss future research directions that could further elucidate how bone marrow failure syndromes arise at the stem cell level.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Optimization of Rectennas for Thermal Energy Harvesting

contributor:
Bakr, Mohamed
Deen, M Jamal
Electrical and Computer Engineering

subject:
Energy Harvesting
MIM Diode
Nano-antenna
Metamaterial
Perfect Absorber
Optimization

abstract: One of the untapped energy sources is the thermal energy available either from solar irradiance which is still not fully utilized or from the ambient heat temperature. Both resources share the nature of infrared (IR) radiation but with different range of wavelengths. The rectenna (rectifying antenna) concept is presented to harvest these IR radiations. The rectenna is simply an antenna connected to a diode. The diode has to be able to follow and rectify the ultra-fast received AC signal. This condition promotes the use of metal-insulator-metal (MIM) diodes due to their ultra-fast tunneling mechanism. The impedance matching between the diode an antenna is to be considered. The resistance practical ranges of both nano-antenna and MIM diode are generally far. The diode responsivity determines the MIM rectification capability. By building MIM diodes with multiple insulator layers the trade-off between the resistance and responsivity can be resolved. An optimization algorithm to select the qualified materials to build an MIIM diode with high responsivity and low resistance is introduced. A Ti-TiO2/ZnO-Al MIIM diode with ultra-thin oxide layers is fabricated. Also, a global optimization approach is carried out to maximize the impedance matching between the diode and the nano-antenna while improving the capacitance effect on the device’s cut-off frequency. The optimal results reveal a maximum coupling efficiency of 5.5%, a responsivity of 6.4 A/W, and a cut-off frequency of ~34 THz. A symmetric MIM metamaterial perfect absorber is introduced. The design has larger resistance than conventional nano-antennas. The near unity absorptivity is achieved through an optimization approach. A novel Chand-Bali nano-antenna that supports dual polarization and wide angle of reception is presented. The rectenna based on this nano-antenna is expected to achieve more than one magnitude of efficiency higher than ones fabricated in literature.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Particle Image Velocimetry Applied to Mixed Convection in a Rectangular Enclosure

contributor:
Shoukri, M.
Wood, P.
Mechanical Engineering

subject:
particle image velocimetry
mixed convection
rectangular enclosure

abstract: An investigation of mixed convection in a rectangular enclosure is presented in which the velocity fields in the enclosure are determined using Particle Image Velocimetry (PIV). Basically, this technique records optical images of flow tracers within a flow field, and determines the velocity field by measuring the displacement of the flow tracers during short time intervals. The components which comprise the PIV system and its operation are described in detail to familiarize the reader with this relatively new technique. The main objective of this investigation is to determine the accuracy and applicability of the PIV technique as a velocity measurement tool. This is accomplished by comparing present experimental velocity results to those obtained by Nurnberg [2] using Laser Doppler Anemometry (LDA). LDA has been proven to be an accurate velocity measurement tool and provides data for evaluating PIV results. A second objective of this research is to use the PIV results to verify a numerical code written by Nurnberg [2] which predicts the velocity fields in the rectangular enclosure. However, the comparison of experimental results of the two measurement techniques revealed that the PIV results were too inaccurate to perform this function. The large amount of error present in this PIV system prompted the recommendation of an improved, more accurate system. Although this improved system is very expensive - approximately $40,000 - it will provide velocity measurements with an accuracy close to that of LDA, at half the cost of an LDA system and with far less time for data acquisition and analysis.

abstract: Thesis

abstract: Master of Engineering (ME)


title: 3D Graphics Application System

subject:
3D graphics
application system

abstract:
This project is about a 3D graphics system for engineers and architects. Its goal is twofold: to provide tools for drawing 3D models, and to create a database support system where data related to these models would be stored (at present the first part has been implemented). Costs, materials, calculations of loads, stresses, and other important factors will be available to the user during the whole design process. The system will therefore allow for drawing realistic projects, not just conceptual visual models.
The drawing tools provided by the system include a few drawing techniques and viewing functions. The system’s drawing routines operate on sets of points, lines, or components so that they are very fast and efficient. This approach to the method of drawing along with the description of the system are given in the following write-up.

abstract: Thesis

abstract: Master of Science (MS)


title: Single Mode Tunable Short External Cavity Semiconductor Diode Lasers

contributor:
Cassidy, D. T.
Reid, J.
Engineering Physics

subject:
tunable external cavity
semiconductor diode lasers

abstract: This thesis describes the use of short external cavity (SXC) semiconductor diode lasers as single longitudinal mode (SM) tunable sources. A SXC forces a multimode diode laser to lase on a single longitudinal mode. Various laser types were investigated in SXC configurations using both planar and spherical external mirrors. The side mode suppression ratio (SMSR) and the SM tuning range were measured with respect to the positioning of the external cavity element. With a planar mirror as the SXC element, SMSR of —33 dB and SM tuning ranges of 1 nm (110% of a mode spacing) were obtained with inverted rib waveguide (IRW) lasers. For external cavity lengths of ~ 60 um the total continuous SM tuning range summed over all modes was found to be 72 cm^-1 or 12 nm. The use of a spherical mirror improved the results. A SXC laser consisting of a spherical mirror and an IRW laser had SMSR values of —37 dB and SM tuning ranges of 1.10 nm. Power and voltage characteristics of SM SXC lasers were also examined. It was found possible to use the laser voltage and electronic feedback to control the external cavity length for optimum SM output. The external differential quantum efficiency (DQE) was found to be wavelength dependent and may be explained by the wavelength dependence of the scattering/absorption loss. One aspect of the characteristic trend of the DQE with respect to wavelength is that it offers the possibility of determining the lasing wavelength of the SM without the use of a monochromator.

abstract: Thesis

abstract: Master of Engineering (ME)


title: Development of InGaAsP/GaAs Diode Lasers for Ultrashot Pulse Generation

contributor:
Haugen, Harold
Mascher, Peter
Engineering Physics

subject:
ultrashort pulse generation
InGaAsP/GaAs
diode lasers

abstract: The groundwork has been completed for a large new research initiative involving the development of diode lasers for moderate power ultrashort pulse generation. This thesis reports on the status of three core areas of this initiative: InGaAsP/GaAs diode laser design and characterization, split contact device testing, and thin film interference filter deposition and characterization. Two new short wavelength diode laser designs have been realized and tested. A 980 nm laser was designed, using an InGaAsP barrier/waveguide region. This showed improved far field performance and better contact isolation as compared to an existing 980 nm laser using GaAs barriers. A laser emitting at 850 nm was also designed using GaAs quantum wells surrounded by a new quaternary waveguide region. A test arrangement was developed to facilitate the measurement of IV and LI curves for split contact lasers. Numerous lasers were tested, indicating that short absorber sections and narrow gap widths are preferable for use as saturable absorbing regions in a passively mode locked diode laser. Finally, thin film silicon oxynitride interference filters have been designed, deposited, and characterized for several antireflecting and high reflectance coatings on semiconductor laser facets. A comparison ofsingle layer AR coatings accounting for the modal reflectivity was performed. A four layer high reflectance coating with a peak broadband reflectance of over 90% was deposited on a laser facet.

abstract: Thesis

abstract: Master of Engineering (ME)


title: Synthetic Jet Actuator for Active Flow Control

contributor:
Ziada, S.
Mechanical Engineering

subject:
synthetic jet actuator
active flow control

abstract:
A long aspect ratio synthetic jet is produced through an axial slit along part of the length of a cylinder. The jet is excited acoustically by a pair of loudspeakers mounted at the cylinder terminations. The study compares between the performance of two different slits with aspect ratios of 273 and 773. The comparison is based on the spanwise distribution of the mean jet velocity and phase between the jet velocity fluctuations and the excitation signal. Three different frequencies and amplitudes are used to excite the speakers covering the range of frequencies used in the control application. For both cases studied the mean centerline velocity of the jet increases with increasing the amplitude of the exciting signal, but decreases with increasing its frequency. Moreover, velocity deficits of up to 30% are evident as the midspan of the cylinder is approached from either end. Similar trends are also observed for the centerline phase distributions of the velocity fluctuations, with deficits of up to 130°. However, it is
observed that for the long slit case the deficits in both the velocity and phase distributions are much larger than those for the short one. The synthetic jet is then mounted in the upstream cylinder of a tandem cylinder arrangement to be used as a control actuator for controlling the vibrations of the
downstream cylinder. A simple feedback control mechanism is used at a Reynolds number of about 6.3x104. This Reynolds number corresponds to the case' where the downstream cylinder’s response is dominated with two frequency components, one at the resonance frequency of the cylinder, which is excited by broadband turbulence in the flow, and the other at the vortex shedding frequency. Both slits studied for the characterization experiments are used to compare their performance as control actuators.
Both jets produce comparable reductions in the vibration of the downstream cylinder. A reduction of about 20% in the total RMS amplitude of the vibrations signal is achieved. This amounts to a reduction of about 50% in the resonant peak and an average value of about 40% in the vortex shedding peak. The optimal values of gain and time lag of the controller are then used to investigate the effect of the jet on the flow. It is found that the short slit jet produced an effect that was traced up to 1.875 diameters downstream, while the effect of the long slit jet dropped dramatically very close to the upstream cylinder.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: CW Mid-infrared NH3 Lasers

contributor:
Reid, John
Jessop, P.E.
Physics

subject:
NH3 lasers
NH3
lasers
mid-infrared lasers
CW mid-infrared NH3 lasers
CW Raman lasers

abstract:
This thesis describes a series of experiments that were undertaken to extend the limits of output power and wavelength coverage of optically pumped mid-infrared lasers. Initially, two new CW Raman lasers operating at wavelengths of 11.5 and 12.5 pm were developed.
Maximum powers of 650 and 150 mW were produced, with pump powers of 11 and 3.3 W, respectively. The effect of the pump offset on the output power was then determined by measuring the efficiency of an NHg laser pumped at frequency offsets of 94 and 274 MHz. In lasers operating in pure NH3, the larger pump offset required a greater pump intensity to reach threshold, but efficiency increased with pump offset. Higher NH3 pressures could be used at larger pump offsets and the improved efficiency was attributed to reduced saturation effects at the higher operating pressures. Experiments carried out with NHg inversion lasers have greatly increased the output powers available at a large number of wavelengths in the 10 to.14 pm range. In a buffered NH3 mixture, the sR(5,0) transition was pumped on resonance. C^llis;o^r^s with either — or Ar buffer gases were effective in thermalizing the rotational populations in the v>2=1 vibrational level and producing gain on a wide range of frequencies. Output powers as large as 3.5 W on a single line and greater than 5 W multi-line were produced, at efficiencies of 20 and 30 % respectively. The number of lasing wavelengths increased substantially, as more than forty ortho-NH3 transitions were observed to lase in a grating-tuned cavity. The optical pumping technique was then used for the first time to produce line-tunable lasing on para-NH3 transitions. The sR(5,l) transition was pumped near resonance and 24 para-transst'lons were observed to lase. In total, lasing was achieved on 65 different transitions in 14NH3, with wavelengths of 10.3 to
13.8 pm.

abstract: Thesis

abstract: Master of Science (MSc)


title: The Numerical Modeling of Particle Dispersion in Turbulent Shear Flows

contributor:
Lightstone, Marilyn
Mechanical Engineering

subject:
numerical model
particle dispersion
turbulent shear flows

abstract: This thesis investigates Stochastic Separated Flow (SSF) models for particle dispersion in turbulent shear flows. A new model is presented that accounts for anisotropy and incorporates a temporal and a spatial autocorrelation in the description of the fluctuating component of the turbulent gas-phase velocity. This model and three SSF models available in the literature are evaluated by comparing predictions with the shear layer experiments of Lazaro and Lasheras (1989), Hishida et al (1992) and the turbulent round jet experiment of Yuu et al (1978). Results are discussed and deficiencies in the models explored. The new model of Evinou and Lightstone compensates for the crossing trajectory effect with the inclusion of a spatial correlation based on the relative velocity of the particle and the time step employed.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Broad-Band Antireflection Coatings for Improved Grating-External-Cavity Diode Laser Performance

contributor:
Cassidy, D. T.
Mascher, P.
Engineering Physics

subject:
broad-band antireflection coatings
diode laser

abstract: In this thesis, strong optical feedback is utilized to realize broad-band wavelength tuning and to stabilize the frequency of a semiconductor diode laser in a grating-external-cavity (GEC) configuration. To reach the regime of strong optical feedback, the laser facet through which the feedback occurs has to be antireflection (AR) coated. Multi-layer AR coatings were designed using SiO2, Si3N4, SiOxNy, and a:Si for specific laser waveguide structures, and were fabricated by an electron cyclotron resonance, plasma enhanced, chemical vapor deposition (ECR-PECVD) system. The film thickness and refractive index were monitored by in situ ellipsometry during the deposition. This scheme permitted very low reflectivities, in the order of 5 x 10-4, to be readily and reproducibly obtained. The diode laser thus obtained was used in a strong feedback configuration. Light emitted from the coated facet was collimated and fed back onto the laser cavity after being reflected off a diffraction grating. The diffraction grating provides frequency selectivity, which is a desirable feature for obtaining a stable single longitudinal mode laser. The laser in this configuration oscillated in a single mode with a greater than 30 dB side mode suppression ratio and a wide tuning range.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Parameter Extraction for Behaviour Modeling of Single Mode Semiconductor Laser Transmitter in Intensity Modulated Direct Detection Fiber-Optic Communication Systems

contributor:
Huang, Wei-Ping
Electrical and Computer Engineering

subject:
parameter extraction
behaviour model
single mode semiconductor
laser transmitter
fiber optic communication system

abstract:
Intensity modulation direct detection (IMDD) transmission scheme has been the mainstay in optical communication ever since semiconductor lasers were put to use as the choice transmission sources. With the development of new improved laser types, this method will continue to dominate the third generation light wave networks where bit rates have steadily risen beyond 10Gbps mark. The main attraction of this scheme lies in its simplicity. With EDFA amplifiers providing a cost effective solution to the attenuation problem, long haul network capacity under the scheme has greatly increased. At the design stage of such systems, it is essential to accurately predict the behavior of each system component right from the laser transmitter up to the optical receiver under custom specific operating conditions and laser diodes are one of the key
components for a wide range of light wave communication systems. For this purpose, computer-aided simulation techniques based on behavioral models of laser diodes have been developed and validated for a variety of applications [4-8]. A ‘representative’ behavior model, which closely approximates the device’s actual physical model, is essential to the system designer. Unfortunately, the component vendor or manufacturer may not be able to provide all the information needed to predict such behavior. The only information that can be made available, are certain measured variables over a specified measurement range. The designer therefore, needs a tool to effectively convert this data into a useful model with sufficiently accurate parameters for predicting behavior. As the complexity of the model increases, more detailed knowledge of the laser is required and the computation time for system performance calculation increases. While
sophisticated models provide considerable insight into important characteristics of the
lasers, for system simulation purposes a relatively simple model is often adequate. In this
thesis we will propose a very robust and efficient procedure for estimating the modal
parameters and go on to propose a complete solution to the 0D laser model extending to
such domains as the below threshold dynamics and temperature effects.

abstract: Thesis

abstract: Master of Engineering (ME)


title: The Amount and Direction of Change of Background Noise as a Conditioned Stimulus

contributor:
Kamin, Leon
Psychology

subject:
background noise
direction of change
conditioned stimulus

abstract: This thesis is concerned with intensity characteristics of conditioned stimuli in acquisition of a conditioned emotional response (CER) in rats. A comparison was made of CSs which differed (between groups) with respect to amount and direction of change in white noise from a constant background stimulation level. The measure of conditioning was the degree to which the CS disrupted ongoing, food-motivated, bar-pressing activity. The major findings were (1) that rate of conditioning was a monotonic increasing function of amount of intensity change in either direction; and (2) an increase in noise intensity from background X to CS Y produced more rapid acquisition of the CER than did a decrease from background Y to CS X. (3) During pretests, a noise increase produced a small, but reliable, Increase in rate of bar-pressing, while a noise decrease produced a slight suppression.

abstract: Thesis

abstract: Master of Arts (MA)


title: The Effect of Contigency on Expectation of Reward in Selective Learning

contributor:
Jenkins, H. H.
Carment, D. W.
Psychology

subject:
contingency
expectation of reward
selective learning

abstract: The experiment was designed to study the effect of conditionality on the growth and decline of expectancy scores during acquisition and extinction. The results revealed that conditionality affects the growth of expectation during acquisition for both direct and vicarious tasks but has no effect on variation scores. Percentage of reinforcement is also effective, the expectancy scores for the 100% reward groups rising to a higher level in acquisition and dropping off more rapidly in extinction than for the 50% reward groups. Problems arising from the differential effect of conditionality on expectancy scores and variation indices, and from differential expectancy levels at the end of acquisition were discussed.

abstract: Thesis

abstract: Master of Arts (MA)


title: Bonding Stress and Reliability of High-Power GaAs-Based Lasers

contributor:
Cassidy, D. T.
Engineering Physics

subject:
bonding stress
high power GaAs laser
GaAs based laser

abstract:
This thesis documents a study of bonding stress and the reliability of GaAs-based lasers for high-power applications. GaAs-based lasers were bonded to oxygen-free high- conductivity (OFHC) copper heat sinks using a eutectic PbSn solder or a silver-filled conductive epoxy, and life tested. Epoxy-bonded devices were observed to have a larger failure rate on life test than solder-bonded devices. Bonding stress, as measured by the degree of polarization (DOP) of photoluminescence, was found to be the largest in epoxy-bonded devices. As well, the type of heat sink and bonding adhesive affected the stress in the laser material, with bonding stress increasing when there was a larger mismatch of coefficients of thermal expansion between the laser material, adhesive and heat sink.
The reliability of the lasers was affected by the amount of force applied to unbonded laser chips. As the applied force increased on a chip centred on a groove, the rate of degradation in the output power increased. A limit in stress tolerance was observed in the lasers, which meant that larger amounts of stress would lead to increased rates of degradation in the output power. As well, the performance of lasers selected from a batch showing poor reliability degraded at an accelerated rate after several hours of operation under applied strain.

abstract: Thesis

abstract: Master of Engineering (ME)


title: Interactive Image Processing and Pattern Recognition of Digitized Flow Patterns

contributor:
Rockwell, Donald
Engineering

subject:
interactive image processing
pattern recognition
digitized flow patterns
manufacturing systems engineering

abstract: In this thesis report, interactive algorithms aid in the analysis of fluid flows are presented. Special functions and algorithms to average, smooth, and calculate the similarity between digitized curves were developed. The developed routines process the images in the spatial domain, thereby eliminating the need to calculate discrete Fourier and inverse Fourier transforms. The algorithms are effective, efficient, and fast. As an integral part of the algorithms, special data buffer routines for the effective data manipulation of curves, as well as cursor routines, were developed. An arbitrary set of frames consisting of curves, or an arbitrary set of curves, can be averaged or smoothed. Curves can be smoothed with a modified, variable, convolution filter. A special function makes it possible to express the similarity of two curves in a numerical value. This technique can be used to study time effects in fluid flows. Noise reduction can be obtained by averaging and smoothing a set of curves.

abstract: Thesis

abstract: Master of Science in Manufacturing Engineering (MSMANFE)


title: Magnetic Resonance Investigations of Ion Transport Phenomena in Lithium-Ion Battery Electrolyte Materials

contributor:
Goward, Gillian
Chemistry and Chemical Biology

subject:
lithium ion batteries
magnetic resonance
MRI
PFG-NMR
ion transport
electrochemical modelling

abstract: The subject of this thesis is the application of magnetic resonance methods to the characterization and quantification of lithium-ion transport in a wide range of lithium-ion battery electrolyte materials relevant to the electromobility and energy storage sectors. In particular, field-gradient magnetic resonance techniques, in the form of PFG-NMR diffusivity measurements of both liquid- and solid-state electrolytes and in situ MRI of electrochemical cells, comprise the core means by which these characterizations were performed. PFG-NMR and ionic conductivity studies of a range of liquid-state electrolyte mixtures were performed, as a function of temperature, to assess how key mass and charge transport properties reflect differences in composition. In situ MRI was used to study the effect of temperature on steady-state concentration gradient formation in polarized liquid electrolytes, with the results quantitatively compared to model predictions. This approach was then extended, using a combination of MRI and spatially-resolved PFG-NMR, to study the interlinked effects of temperature and current density on concentration gradient formation, and to attempt a comprehensive characterization of the ion transport parameters with spatial resolution. Finally, PFG-NMR and MAS-NMR were applied in a solid-state electrolyte context to investigate compositional effects on ion transport in the argyrodite family of lithium-sulphide ion conductors, and the influence of macroscopic sample format (glass, crystalline powder, compressed crystalline pellet) on micro-scale ion transport in a thio-LISICON ion conductor. Taken together, the studies demonstrate the effectiveness of magnetic resonance methods for the robust elucidation of the means by which material properties impact ion transport in technologically-relevant lithium-ion electrolyte systems.

abstract: Dissertation

abstract: Doctor of Science  (PhD)

abstract: Lithium-ion batteries are a critical component of the ongoing efforts to transition the global automobile fleet to electric vehicles and integrate renewable energy sources into the electricity grid. An important aspect of designing and optimizing lithium-ion batteries is a comprehensive understanding of the factors which impact the ability of the electrolyte in the battery to ferry the lithium ions from one electrode to the other, the process which enables them to release energy into the circuit to power a device. This thesis describes results obtained from measuring the diffusion of the ions within the electrolyte for both conventional liquid-state electrolytes, and emerging solid-state electrolyte materials. It also includes studies which make use of MRI to image the flow of ions within the liquid-state electrolyte of an operating battery mimic, and monitor the concentration changes of the ions across the electrolyte as a current is applied to it.


title: The process of caring: Nurses' perspectives on caring for women who end pregnancies for fetal anomaly

contributor:
Pawluch, Dorothy
Sociology

subject: Sociology Sociology

abstract: Grounded theory research was conducted with forty-one female, registered nurses from four Canadian hospitals who manage the genetic termination (GT) procedure for women who end a wanted pregnancy due to fetal anomaly. Based on the sociological concept of dirty work , interest focused on nurses' experiences with work that is viewed as unpleasant and undesirable, work that others would prefer not to do or even know about. The hospitals' inadequate organization and low priority of the GT procedure have largely contributed to the problems GT nurses face. These include lack of professional backup, lack of adequate procedures, protocols and policies, lack of specialized training, lack of choice and lack of support. GT nurses readily discuss a working situation fraught with uncertainties, tensions, dilemmas and frustrations, yet they also describe this work as professionally rewarding and personally gratifying. They found two central strategies to respond to the dirty work dimensions of their job. First, nurses see GT patients as presenting a unique opportunity for them to put into practice the most fundamental and core values of their profession--patient-centered care. Second, nurses have created a routine that allows them to more efficiently manage their work, caring for patients the best way they can. The exploration of these strategies led to a number of paradoxes experienced by the nurses. First, their isolation which is a part of the problem, also proved to be part of the solution as it afforded them a measure of professional and moral autonomy. Second, there is a built-in tension between the caring role and the routinization of the procedure that nurses managed by focusing on the unique aspects of GT work. Third, due to the intensely emotional aspects and ethically contentious nature of GTs, nurses care not only for their patients' emotional well being but their own as well. Fourth, nurses saw themselves as having two patients to care for, a mother at risk of needing emergency care and a stillborn baby. Fifth, a subtle degree of coerciveness exercised over the nurses made it clear that if they did not participate in GTs they may face possible disciplinary measures or risk losing camaraderie with their nursing colleagues. The strategies illustrate that amidst professional and ethical constraints GT nurses do not acquiesce to institutional powerlessness. Instead by interacting and negotiating with nurse colleagues and challenging the structure of the hospital and physicians' views, GT nurses have taken advantage of situational circumstances to strengthen their professional influence and provide the best possible care for their patients.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: STRATEGIES TO FACILITATE EVIDENCE-INFORMED AND PARTICIPATORY HEALTH POLICY MAKING IN ETHIOPIA

contributor: Clinical Epidemiology/Clinical Epidemiology & Biostatistics

subject: evidence-informed policy making

subject: Ethiopia

subject: strategies

subject: Prevention of mother-to-child transmission (PMTCT) of HIV

subject: Agenda setting

subject: Policy development

subject: Multiple streams framework (MSF)

subject: 3ie framework

subject: participatory health policy making

subject: Peer ressearchers

subject: modified delphi

subject: paper-based and e-Delphi

abstract: Evidence-informed health policy making contributes to improved health outcomes by strengthening health systems. In addition, health policy decisions should take into consideration the needs and priorities of users of healthcare services. However, little research has been done to find best ways to facilitate evidence-informed and participatory health policymaking, particularly in low- and middle-income countries. This thesis is written based on three studies done in Ethiopia to fill this knowledge gap. In the first study, we examined whether, how and under what conditions evidence was used and service-users participated during the agenda-setting and policy formulation phases of selected policies in the ‘prevention of mother-to-child transmission of HIV’ program in Ethiopia using a multiple-case study design. In the second study, we identified strategies to facilitate evidence-informed health policy making using an online survey. In the third study, we identified strategies to facilitate participatory health policy making using a combined paper-based and Internet-based Delphi approach. The thesis does not have direct theoretical contribution. However, it will draw on two theoretical frameworks, namely Kingdon’s framework and the 3I+E framework.  and use them in a setting from where they were originally developed. This thesis has two substantive and three methodological contributions. Substantively, the first study provides empirical evidence about the current practice of evidence-informed and participatory health policy making in a low-income, ‘revolutionary’ democratic country (Ethiopia). In addition, the studies have identified strategies to concretize the constitutional and policy provisions for evidence-informed and participatory health policy making in Ethiopia. The thesis has the following three methodological contributions. First, the studies explored the use of Kingdon’s multiple-streams framework and the 3I+E framework in predicting factors influencing agenda-setting and policy formulation phases, respectively, and in explaining the use of research evidence in informing these two phases in a ‘revolutionary’ democratic country where they have not previously been used. Second, the thesis has shown that paper-based and Internet-based Delphi could be combined in contexts with limited resources. Third, the thesis has demonstrated the possibility of training service-users as ‘peer’ researchers to collect and analyze data to inform their participation and maximize their contribution in surveys, forming a pyramid of participation.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Evidence-informed health policy making can contribute to improved health outcomes by strengthening health systems. In addition, health policy decisions ultimately affect users of healthcare services. Thus, such decisions should take into consideration their needs and priorities. However, little research has been done to find best ways to facilitate evidence-informed and participatory health policymaking, particularly in low- and middle-income countries. This thesis is written based on three studies done in Ethiopia. In the first study, we examined whether, how and under what conditions evidence was used and service-users participated in the ‘prevention of mother-to-child transmission of HIV’ program in Ethiopia. In the second and third studies, we identified strategies to facilitate evidence-informed and participatory health policy making. In addition, we explored the possibility of combining Internet- and paper-based methods for consensus-building among policymakers, program managers, researchers, healthcare providers and service-users in settings with limited resources.


title: Spectatorship and Fandom of the Roman Chariot Races

contributor:
George, Michele
Classics

subject:
circus
chariot
chariot races
Rome
fans
spectatorship
sport

abstract:
This dissertation is concerned with the spectators of the Roman chariot races throughout the empire.  It addresses how the sport was experienced and engaged with in the Roman context, with consideration of the everyday lives of circus fans, social networks and consumer patterns.  By making use of a variety of sources, including the structural remains of circuses, material culture, epigraphic evidence, and both literary and historical writings, it is possible to gain a picture of a vibrant community of circus fans that as a group were able to make an impact on the sport as well as on Roman society and culture more broadly.
	Circus spectators were confronted with an array of stimuli from the moment of their arrival at the venue - from the sights to the sounds and even the feel of the seats - all of which added to their shared experience.  Audience members engaged not only with the sport but also with one another, finding common ground in their collective interest in the races.  Aside from the casual spectator, many audience members identified themselves to be within a community of fans with common views and beliefs concerning the popular spectacle.  Fans of the races passionately followed the sport and its competitors, and offered their support when in attendance at the circus and in their actions outside of the venue.  An examination of the phenomena of Roman sport spectators further reveals a rich sub-culture of racing fans that offered an active social experience at the circus and various methods of engagement with the sport at the venue and beyond.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Type 2 diabetes mellitus risk and prevalence: a descriptive study in communities of the Zamboanga Peninsula, Philippines

contributor:
Agarwal, Gina
Health Research Methodology

subject:
T2DM, Type 2 diabetes
prevalence
prediabetes
Philippines, LMICs

abstract:
Background: Diabetes is an important cause of morbidity, mortality, and health-system costs worldwide. The growing burden of T2DM particularly in developing countries has directed more attention to primary prevention. This cross-sectional study assessed the prevalence of T2DM and its risk factors among general and diabetic populations of the Zamboanga Peninsula, Philippines.

Methods: This was a multi-center community-based cross-sectional study. 2624 individuals 40 years old or older residents (100 persons per Barangay of total 26 barangays) of the Zamboanga Peninsula province have been chosen via door-to-door systematic random sampling procedure. Personal demographic, anthropometric and lifestyle information was collected using a structured questionnaire. Weight, height, WC, BMI, and HbA1c test was were obtained through participant measurements.

Results: Valid data of 2572 (98.01%) individuals analyzed, mean ±SD of age was 57.39 ± 10.41 and 1843 (71.7%) of participants were women. Based on ADA 2018 guideline, the prevalence of T2DM and prediabetes were 18.3% and 26.7%, respectively. The frequency of having T2DM and prediabetes was higher in older people (p< 0.05). Urban areas had a significantly higher prevalence of diabetes, prediabetes compared with rural areas (p< 0.01). 54.4 % of the population had a normal body mass index while 45.6% of the population were overweight (32.1 %) or obese (13.5%), and 65% had high or elevated WC. There was a significant association between BMI /central obesity and glucose abnormalities (P<0.01). The prevalence of overweight, obesity and abdominal obesity was significantly higher in women and the older age groups had significantly lower BMIs/ abdominal obesity than younger age groups. 40.4% of the participants had HTN and the prevalence of HTN was significantly higher in the older age groups and female participants. The prevalence of HTN and family history of diabetes were higher in T2DM patients and individuals with prediabetes (P<0.01). Based on the FINDRISC score, the risk of developing diabetes was high or very high in 17.6% and moderate in 20.0% of the population.

Conclusion: The prevalence of T2DM and prediabetes was higher in this study compared to previous surveys in the country. This finding highlights the need for public health efforts to improve T2DM risk factors such as obesity and hypertension in this population.

abstract: Thesis

abstract: Master of Science (MSc)


title: Mean Velocity Prediction and Evaluation of k-E Models in Turbulent Diffuser Flows

contributor:
Turan, O. F.
Mechanical Engineering

subject:
velocity prediction
turbulen diffuser flow

abstract: Eight decreasing adverse pressure gradient flows, and the similar regions of an initially increasing adverse pressure gradient flow, are examined in terms of the two experimentally observed half-power regions. The existing semi-empirical and analytical mean velocity profiles are examined and their range of applicability is determined in terms of the ratio of outer to inner half-power slopes. Three variations of the k-e model of turbulence are evaluated in terms of how well they predict the turbulence field in an eight degree conical diffuser. The model of Nagano and Tagawa (1990) is seen to be superior to the others. It is possible for Nagano and Tagawa’s model to yield reasonable prediction of k and E because they implemented the Hanjalic and Launder (1980) modification for the irrotational strains. However, the k-e models prediction of the Reynolds stresses is poor.

abstract: Thesis

abstract: Master of Engineering (ME)


title: Country Risk Classification and Multicriteria Decision-Aid

contributor:
Peng, Jiming
Computing and Software

subject:
risk classification
decision aid

abstract:
Country risk is an important concern in international business. Country risk classification refers to determining the risk level at which a country will not repay its international debt. Traditionally, country risk classification resorts to statistics methods such as discriminant analysis. In the past two decades, the so-called multicriteria decision aid (MCDA) methods have been proved to enjoy better performance than the standard statistics methods. Nevertheless, the performance of the MCDA methods is still far away from satisfactory and
can be improved significantly. The better performance of several MCDA methods, such as UTADIS (UTilités Additives DIScriminantes) and MHDIS (Multigroup Hierarchical Discrimination), is achieved by exploiting the rater’s background knowledge. In the standard MCDA model, we assume that the criterion function for every factor is monotone and all the factors are independent. Then, we approximate the impact of every factor and use the sum of the corresponding criterion functions to determine the risk level of a country. By discretizing the feasible domain of the factor, the MCDA method solves a linear program to find a classifier for country risk classification. This thesis tries to enhance the capability of MCDA methods by allowing a class of non-monotone criteria: the unimodal ones. For this purpose, we developed an integer quadratic (non-convex) program for general unimodal criteria. Further, if we restrict ourselves to convex or concave unimodal criteria, then we can still use a linear program to find a classifier. For the case where all the factors are correlated, a simple quadratic form of aggregation is proposed to deal with it. Compared with the original UTADIS model, our generalized model is more flexible and can deal with more complex scenarios. Finally, our generalized model is tested based on cross-validation and our experiment is carried out under the AMPL+sovers environment. Promising numeric results indicate that except for its theoretical advantages, our generalized model exhibits practical efficiency and robustness as well.

abstract: Thesis

abstract: Master of Science (MS)


title: LIVING DISABILITY: WAYS FORWARD FROM DECONTEXTUAL MODELS OF DISABILITY

contributor:
Gedge, Elisabeth
Philosophy

subject: phenomenological hermeneutics, medical model of disability, social model of disability, methodological critique, disability studies, Bioethics, narrative bioethics, principlist bioethics, phenomenology, hermeneutics, autism, autobiography, Hilde Lindemann Nelson, John Arras, vulnerability, personal identity, indeterminacy, relational autonomy, feminist ethics, Emmanuel Levinas, Sexual ethics, sexual consent, feminist theory, yes means yes, no means no, disability, embodiment, melancholia, Solidarity, social justice, disability, imagination, realism, pragmatism, bioethics, Alexis Shotwell, Richard Rorty, Democracy, Nature, Culture, translation, mediation, hybrid, disability, Bruno Latour

abstract:
Living Disability: Ways Forward from Decontextual Models of Disability consists
of six articles that provide both theoretical and pragmatic commentaries on decontextual
approaches to vulnerability and disability. In What Contemporary Models of Disability
Miss: The Case for a Phenomenological Hermeneutic Analysis I argue many commonly
accepted models for understanding disability use a vertical method in which disability is
defined as a category into which people are slotted based on whether or not they fit its
definitional criteria. This method inevitably homogenizes the experiences of disabled
people. A hermeneutic investigation of commonly accepted models for understanding
disability will provide an epistemological tool to critique and to augment contemporary
models of disability. In A Phenomenological Hermeneutic Resolution to the Principlist-
Narrative Bioethics Debate Narrative, I note narrative approaches to bioethics and
principlist approaches to bioethics have often been presented in fundamental opposition
to each other. I argue that a phenomenological hermeneutic approach to the debate finds a
compromise between both positions that maintains what is valuable in each of them.
Justifying an Adequate Response to the Vulnerable Other examines the possibility of
endorsing the position that I, as a moral agent, ought to do my best to respond adequately
to the other’s vulnerability. I contend that, insofar as I value my personal identity, it is
consistent to work toward responding adequately to the vulnerability of the other both
ontologically and ethically. Who Can Make a Yes?: Disability, Gender, Sexual Consent
and ‘Yes Means Yes’ examines the ‘yes means yes’ model of sexual consent, and the
political and ethical commitments that underpin this model, noting three fundamental
Ph.D. Thesis – C. Kavanagh; McMaster University - Philosophy
v
disadvantages. This position unfairly polices the sexual expression of participants,
particularly vulnerable participants such as disabled people, it demands an unreasonably
high standard for defining sexual interaction as consensual, and allows perpetrators of
sexual violence to define consent. In Craving Sameness, Accepting Difference: The
Possibility of Solidarity and Social Justice I note realist accounts typically define
solidarity on the basis of a static feature of human nature. We stand in solidarity with
some other person, or group of people, because we share important features in common.
In opposition to such realist accounts, Richard Rorty defines solidarity as a practical tool,
within which there is always an ‘us’, with whom we stand in solidarity, and a ‘them’,
with whom we are contrasted. I argue that by understanding Rorty’s pragmatic solidarity
in terms of the relational view of solidarity offered by Alexis Shotwell, it is possible to
conceptualise solidarity in a manner that allows for extending the boundaries of the
community with whom we stand in solidarity. In Translating Non-Human Actors I
examine Bruno Latour’s position that nonhuman things can be made to leave
interpretable statements, and have a place in democracy. With the right types of
mediators, the scientist can translate for non-humans, and those voices will allow for nonhuman
political representation. I wish to suggest that, like scientists, people with
disabilities are particularly capable of building networks that facilitate translation
between humans and non-humans.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Living Disability: Ways Forward from Decontextual Models of Disability consists of six separate articles that provide both theoretical and pragmatic commentaries on decontextual approaches to vulnerability and disability. The first three articles examine contemporary approaches to understanding vulnerability and disability, and explore what a contextual theoretical approach, one that puts the experiences of people with disabilities at the centre, might look like. The second three articles provide a bioethical examination of practical ethical questions associated with the treatment of people with disabilities when it comes to social and political positions on disability and sexuality, solidarity with people with disabilities, and the relationship between people with disabilities and objects.


title: Human Dignity: In (pragmatistic) defence of a (purportedly) useless concept

contributor:
Igneski, Violetta
Philosophy

subject: dignity

abstract:
Is human dignity as critics deride it: a useless concept that is as devoid of philosophical substance as a slogan on a bumper sticker? Or are philosophico-methodological expectations to blame for its critical demise?
   The latter possibility—left unexplored until now—raises three related questions. First, is dignity too vague (or metaphorical) to be meaningful? Chapter I provides voluminous evidence to the contrary. Second, is dignity the basis of moral equality? Chapter II examines the unexpected complications of operating on that noble-seeming assumption. Third, is the very idea of human dignity symptomatic of species snobbery? Possibly, but it’s been said that dignitarians—worse than being species snobs—are full-blown human supremacists. Chapter 3 probes that polemical charge and finds it wanting.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)

abstract: How did the hallmark of humanity’s highest qualities sink to the lows of a (supposedly) empty slogan? Is it because the concept of dignity is so muddled as to be meaningless? Or has it been disparaged as incurably vague for methodological reasons that, though woefully under-researched, might better explain its embattled status? This dissertation addresses—and remedies—the lack of philosophical interest in the latter possibility.


title: EMPLOYMENT OF INDIVIDUALS WITH NEURODEVELOPMENTAL DISORDERS: A SCOPING REVIEW OF CONTEXTUAL FACTORS

contributor:
Rosenbaum, Dr. Peter
Global Health

subject: Neurodevelopmental disorders

subject: Employment

subject: Contextual factors

subject: International Classification of Functioning, Disability and Health (ICF)

abstract:
Background: Individuals with neurodevelopmental disorders are unemployed or underemployed at staggering rates. Employment for this population is impacted by many factors, including contextual issues. This review was conducted to enhance understanding of contextual factors influencing employment procurement for individuals with neurodevelopmental disorders.
Methodology: The Arksey and O’Malley scoping review framework was utilized to examine five databases and sources of grey literature regarding the contextual factors influencing employment procurement for individuals with neurodevelopmental disorders. Articles were analyzed using the International Classification of Functioning, Disability and Health criteria for Contextual Factors, including both Environmental and Personal Factors.
Results: The findings from 41 articles indicate that Contextual Factors, Environmental Factors and Personal Factors influence employment procurement by creating both barriers and facilitators to obtaining employment for individuals with neurodevelopmental disorders.
Conclusion: A focus on contextual factors that impact individuals with neurodevelopmental disorders may provide further insight into the facilitators and barriers influencing employment outcomes. Further research should aim to understand the strength of relationships and to expand the use and application of the International Classification of Functioning, Disability and Health’s biopsychosocial framework. This research can aid in promoting the employment outcomes for individuals with neurodevelopmental disorders.

abstract: Thesis

abstract: Master of Science (MSc)


title: THE EFFECTS OF CANNABIDIOL AND CANNABINOL ON C2C12 MYOBLAST PROLIFERATION AND DIFFERENTIATION

contributor:
Parise, Gianni
Kinesiology

subject: nutrition, myoblasts, muscle growth, cannabidiol, cannabinol, cell culture

abstract:
Increasing interest has emerged in the field of nutrition and its role in promoting skeletal muscle growth. Recently, studies using both in vitro and in vivo models have suggested that cannabidiol – a constituent of Cannabis Sativa – can increase the growth and regenerative capacity of skeletal muscle stem cells. Other isolated compounds, such as cannabinol, have demonstrated anti-inflammatory effects in vivo. Due to the potential benefits of both compounds, our primary objective was to further elucidate the effects of cannabidiol and cannabinol on murine C2C12 myoblast proliferation and differentiation. We hypothesized that supplementation of cannabidiol and cannabinol would augment gene expression of myogenin, leading to enhanced myotube formation; as well as, induce greater gene expression of Myf5 and MyoD, accompanied by increased cell proliferation. In relation to skeletal muscle growth, myostatin and follistatin can substantially impact the regulation of hypertrophy; with down-regulation of myostatin being a potent stimulus for muscle growth, and follistatin being the antagonist to myostatin, we therefore examined if cannabidiol or cannabinol influenced these two proteins, as a possible rationale for increased myogenesis. In this study, cells were treated with either: (1) cannabidiol, (2) cannabinol, (3) or vehicle control (methanol). Cells were grown for 48 hrs in their respective media, the MTT assay was used to assess proliferation. Muscle differentiation experiments required cells to grow for seven days with media supplemented with the respective compound.  The media was changed every 48 hrs. The extent of muscle differentiation was assessed via immunocytochemical and qPCR analysis. In preliminary experiments, cell proliferation was influenced by the duration of
which cells were exposed to the compound and concentration of the compound within the media. It was noted that changing growth media and compound every 24 hrs augmented the proliferative response compared to leaving it on for 48 hrs for both cannabidiol and cannabinol (p<0.05). Furthermore, supplementing cells with cannabidiol at a 1 or 5 uM concentration resulted in considerable cell growth compared to vehicle control (p<0.0001). Cannabinol at 5 uM showed the same effect (p<0.0001). We also quantified the mRNA expression of genes involved in the myogenic regulatory pathway in proliferating and differentiating cells. Herein we report that using a 5 uM concentration of cannabidiol or cannabinol did not increase the expression of any of these genes in proliferating or differentiating cells. These findings help further characterize the effects of cannabidiol and cannabinol on the myogenic response.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: Nutrition impacts the regulation of skeletal muscle mass, with many individuals turning to supplements as a means to improve overall health. Cannabidiol – a constituent of the cannabis plant – has been used over the past several decades for its anti-inflammatory, neuroprotective, and anxiolytic properties; however, recent evidence has revealed its potential effectiveness in promoting muscle growth. If true, there is a possibility that it can be used to target the age-related loss of muscle mass, sarcopenia, or even improve athletic performance. Other derivatives, such as cannabinol, have seldom been studied but also demonstrate anti-inflammatory effects. Therefore, this thesis further elucidates the effects of cannabidiol and cannabinol on the myogenic signaling pathway. As a model, we used the murine C2C12 cell line that recapitulates the behaviour of human myoblasts. Interestingly, the data presented herein supports the notion that cannabidiol and cannabinol only promote cell growth and have no effect on myoblast maturation and myotube formation. These findings provide a better understanding of the potential for cannabidiol and cannabinol as a nutritional supplement targeting skeletal muscle.


title: Following Spoken Instructions in L1 and L2: The Effects of Language Dominance, Working Memory, Cognitive Complexity, and Language Acquisition Background

contributor:
Service, Elisabet
Cognitive Science of Language

abstract: This thesis investigates cognitive aspects of following spoken instructions in bilinguals’ dominant and non-dominant languages. The aim was to increase our understanding of the cognitive benefits and costs of information processing and performance in a second language (L2) compared with a first language (L1). I hypothesized that L2 tasks are associated with more computational and cognitive costs, even in highly proficient bilinguals. In three empirical studies, I examined to what extent factors such as the language of task, working memory capacity, phonological memory, and variables in bilinguals’ language history affect processing and performance of sequences of oral instructions in L1 and L2. Furthermore, I manipulated the psycholinguistic complexity of sequential temporal order to see how it influences bilinguals’ processing and performance, and how it interacts with other variables. Contrary to similar monolingual studies, I tested bilingual participants in two separate sessions, and applied mixed effects logistic regression models to analyze the data. The results suggest that language dominance significantly affects bilinguals’ processing and performance of sequential verbal instructions, with a disadvantage for tasks presented in the non-dominant language. Bilinguals’ recall accuracy was consistently superior when the target sentences were presented in L1. Working memory capacity and phonological memory correlated with instruction-following abilities, especially, in less-proficient bilinguals. Individuals with more available working memory resources were more likely to have better processing and performance in following sequences of spoken instructions. The psycholinguistic complexity of temporal order expressions affected the ability to follow sequential oral instructions, causing lower recall accuracy when the surface order of events was incongruent with the factual order of events in complex instructions. A number of variables in bilinguals’ language background, specifically the age of initial L2 acquisition, level of L2 proficiency, L2 use, and L2 exposure also predicted performance, especially, in less-skilled bilinguals. To the best of my knowledge, this is the first empirical study that has investigated the effects of using a non-dominant language on following instructions modelled on real-world tasks in an office workplace.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Combustion Synthesis and Mechanical Properties of SiC Particulate Reinforced Molybdenum Disilicide

contributor:
Wilkinson, D. S.
Petric, A.
Materials Science and Engineering

subject:
combustion synthesis
mechanical properties
SiC particulate
molybdenum disilicide

abstract: Intermetallic composites of molybdenum disilicide reinforced with various amounts of silicon carbide particulate were produced by combustion synthesis from their elemental powders. Elemental powders were mixed stoichiometrically then ball-milled. The cold- pressed mixture was then chemically ignited at one end under vacuum at approximately 700°C. The combustion temperature of the process was approximately 1600°C which was lower than the melting point of molybdenum disilicide. This processing technique allowed the fabrication of the composites at 700°C within a few seconds, instead of sintering at temperatures greater than 1200°C for many hours. The end product was a porous composite, which was densified to >97% of the theoretical density by hot pressing. The grains of the matrix were 8-14 μm in size surrounded by SiC reinforcement of 1-5 μm. The morphology and structure of the products were studied by x-ray diffraction and scanning electron microscopy (SEM). Samples were prepared for hardness, fracture strength, and toughness testing at room temperature. There were improvements in the mechanical properties of the composites with increasing SiC reinforcement. The hardness of the materials increased from 10.1 ± 0.1 GPa (959 ± 13 kg/mm2) to 11.7 ± 0.6 GPa (1102 ± 52 kg/mm2) to 12.7 ± 0.4 GPa (1199 ± 36 kg/mm2) with the 10 vol% and 20 vol% SiC reinforcement, respectively. The strength increased from 195±39 MPa to 237±39 MPa with 10 vol% and to 299 ± 43.2 MPa with a 20 vol% SiC reinforcement. The fracture toughness increased from 2.79 ± 0.36 MPa.m1/2 to 3.31± 0.41 MPa.m1/2 with 10 vol% SiC and to 4.08± 0.30 MPa.m1/2 with 20 vol% SiC. The increase in hardness and flexural strength is due to the effective load transfer across the strong interface in the composites. The main toughening mechanism is crack deflection by the residual stress in the materials, induced by the differences in the thermal expansion coefficients and the elastic moduli of the matrix and reinforcement.

abstract: Thesis

abstract: Master of Engineering (ME)


title: Biomechanical tools for assessing foot and ankle injury risk in frontal automotive collisions

contributor:
Quenneville, Cheryl
Biomedical Engineering

subject:
Injury biomechanics
Foot/ankle injury
Impact
Anthropomorphic Test Device (ATD)
Ankle posture
Injury assessment

abstract:
Injuries to the lower extremity are frequent and severe in frontal automotive collisions, often leading to pain and long-term impairment. Most injury criteria developed for the lower extremity are conducted with the foot and ankle in a neutral posture, do not take into account footwear, and assess injury risk to the entire lower extremity at the tibia. An instrumented boot, designed to address some of these challenges, was calibrated over a range of impact energies expected in frontal automotive collisions. A dynamic calibration method was developed to convert changes in voltage across a piezoresistive polymer to the applied axial force.
The instrumented boot was then used to examine the axial impact response of two commonly used Anthropomorphic Test Device (ATD) lower legs, under altered ankle postures. Both posture and ATD model were found to affect the load distribution on the foot, highlighting the need to establish injury limits for non-neutral postures as well as selecting the appropriate ATD model. The instrumented boot provided regional loading information that was not reflected in standard industry metrics, emphasizing the importance of increased instrumentation in this area.
A technique was developed for mounting cadaveric feet to ATD tibia shafts, in order to gather industry-relevant load data while examining the impact characteristics of the foot. Load data were collected at the plantar surface of the foot using the instrumented boot, as well as the tibia load cells in the ATD shaft, that highlighted differences in load transmission through cadaveric and ATD feet.
Understanding the impact characteristics of ATDs under non-standard ankle postures as well as examining the load transmission through cadaveric feet highlighted some shortcomings with current injury assessment techniques. The results of this work can be used to improve future collision testing practices, in order to reduce the incidence of lower extremity injuries.

abstract: Thesis

abstract: Master of Applied Science (MASc)

abstract:
Foot and ankle injuries are common in automotive collisions and often lead to pain and long-term impairment. Experimental work on these types of injuries is traditionally conducted with the foot and ankle positioned in a neutral ankle posture, which does not reflect the range of ankle postures individuals may assume in a car crash.
The purpose of this work was to use biomechanical tools to assess foot/ankle injury risk. Impact testing was performed on two commonly used crash test dummy lower legs in conditions relevant to those experienced in car crashes. A technique was developed to mount cadaveric feet to crash test dummy tibias to gather injury information of the foot, while also collecting load data in the tibia shaft – relevant metrics for industry crash testing.
The results of this work outline the shortcomings of traditional injury assessment methods and may be used to improve future practices.


title: SPECKLE SUPPRESSION IN HANDHELD LASER PROJECTION DISPLAYS

contributor:
Xu, Chang-qing
Engineering Physics

abstract:
Micro-/pico-projectors are exciting technology as they represent a core enabling technology for the future growth of portable devices. They are currently involved in many fields such as automotive, defence & aerospace, healthcare, and media/entertainment. Solving the issue of speckle noise in such small projectors has been a challenge until now, as most of the effective techniques for speckle suppression are not suitable for such small sizes.
The purpose of this dissertation is exploring and applying practical solutions for reducing the laser speckle noise for a handheld laser projector (micro-/pico-projectors).
The first method is to introduce a laser source with low-level speckle noise. The source is designed based on end pumping of two cascaded laser crystals in the same cavity. The first crystal is Nd: YVO4  and the second is Nd: GdVO4 crystal. The output power ratio is adjusted mechanically to be 1:1. The output optical to optical efficiency is close to 50%. The output power at 1:1 power ratio has the lowest speckle noise level. The laser source is compact. Such a laser source is promising for micro-/pico-projectors.
The second method is to reduce the laser speckle noise by a simple, low cost and compact optical method. Our novel method is to vibrate a lens with a small focal length in just one dimension (1D) in front of an optical diffuser. The method reduced the speckle noise by 81.25% and 75.6% for laser diode (LD) and diode-pumped solid-state (DPSS) laser sources, respectively.
Finally, an optimisation was performed as follows: First, two laser sources are blended under specific conditions. Second, by adding another vibrating lens with a direction of vibration orthogonal to that of the first lens. Afterwards, the two optimisations are tested with a real pico-projector engine setup. The speckle contrast ratio was < 5%.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Projection display technology today has garnered a large amount of interest due to its vast market. The display technology has evolved alongside the development of various light sources for their light engines. For example, the technology started with the use of a conventional lamp, progressed to light-emitting diodes, and recently has arrived at laser sources. Laser-based projection displays have caught the attention of those seeking to develop display technologies due to many advantages for projection, thanks to the intrinsic properties of the laser. Laser projectors have significant benefits that include high brightness, wide colour gamut, long lifetime and high electrical to optical efficiency. There have been multiple types of laser-projector created to satisfy the requirements of the intended applications. A large scale and high-power laser projector will be used in applications requiring a big screen, large audiences, and wide-open spaces found in a cinema or theatre. A mini projector on the other hand will typically be used for home cinema, while micro-/pico-projectors are intended for personal use. Although laser projectors up until now have been useful, they are expensive and have safety concerns. Moreover, laser projectors encounter a technical problem due to the high coherence of the laser source. This issue is known as “speckle” noise. Speckle noise results in a reduction of the quality of images generated with laser-based projectors. Many types of research have been conducted to reduce the laser speckle noise to be lower than human eye perception limits. As a result, most of these speckle reduction techniques are applied to large scale projectors, and a few of them have been successfully applied for smaller projectors, such as micro-/pico- projectors.


title: Pre-Transformation Phenomena in the Intermetallic Compound TiNi

contributor:
Purdy, G.R.
Engineering

subject:
Pre-transformation phenomena
Intermetallic
TiNi

abstract: Prior work in this system has indicated that, under favourable conditions, the formation of a martensitic transformation product on cooling may be preceded by a second-order cubic-rhombohedral transformation. In the present investigation, thin-film electron microscopy and diffraction have been employed to study the pre-transformation phenomena in the temperature range 20-300 °C. The results are interpreted in terms of localized thermal diffuse scattering, resulting from the transformation, in terms of lattice dynamics, is suggested. dark field micrographs of the rhombohedral phase suggest a moderate degree of co-operation between adjacent domains. Additional data is provided in the form of volumetric and x-ray intensity measurements.

abstract: Thesis

abstract: Master of Engineering (ME)


title: The Vapour-Phase Reaction of 2-Alkyltetrahydropyrans with Aniline over Alumina

contributor:
Bourns, A. N.
Chemistry

subject:
vapour-phase reaction
aniline

abstract: The vapour-phase reaction of 2-methyl-tetrahydropyran and 2-ethyltetrahydropyran with aniline over an activated alumina catalyst has been studied. The product, in each case, consisted of a mixture of an N-arylpiperidine, an N-arylpyrrolidine formed by ring contraction, and two N-alkenylanilines formed by ring opening. The structures of the nitrogen heterocyclic compounds were established by independent syntheses involving the reaction of the appropriate dibroinoalkane with aniline. The N-alkenylanilines were characterised by hydrogenation to known N-alkylanilines and by identification of the osonolysis products.

abstract: Thesis

abstract: Master of Science (MS)


title: A Crystat for Determinations of the Latent Heat of Liquid Helium

contributor:
Mate, C. F.
Physics

subject:
cryostat
latent heat
liquid helium

abstract:
A cryostat has been constructed for the determination of latent heat of vaporization of liquid helium at temperatures from the critical temperature (5.2°K) to below the A point (2.2°K). Some details of the apparatus, hints on low temperature technique and suggestions for future equipment are
presented, together with results of some experiments on the apparatus.

abstract: Thesis

abstract: Master of Science (MS)


title: Responses of Human Infants to Novel Stimuli

contributor:
Wardwell, E. S.
Psychology

subject:
human infant
novel stimuli
stimuli
human baby

abstract:
This thesis is concerned with the responses of human infants to novel visual stimuli. Novelty
is defined in terms of a time dimension so that a stimulus which is presented to the subject
for a period of time (familiarisation period) is said to be novel relative to a stimulus
which has not been so presented. Experiments demonstrated that infants will fixate a novel
stimulus longer than they fixate a familiar stimulus. This effect was shown to be greater
when familiar and novel stimuli differ from each other in two dimensions than when they
differ in only one dimension. The decline in responsiveness to stimuli presented for a
familiarisation period was shown to be a linear function of time.

abstract: Thesis

abstract: Master of Arts (MA)


title: The Study of Flooding Correlations of Counter-Current Two-Phase Flow in a Vertical Tube under Electric Field

subject:
flooding correlation
two-phase flow
electric field

abstract: A counter-current two-phase flow under an applied electric field has been studied theoretically using potential flow equations. A flooding correlation has been derived taking account of applied electric field on the interface for both adiabatic and condensing system. It is found that the electric field enhances flooding phenomena in case of adiabatic system. In the case with system involving condensation the electric field enhances flooding at low liquid flow rates and at high liquid flow rates the flooding point decreases under electric field depending on the rate of subcooling.

abstract: Thesis

abstract: Master of Engineering (ME)


title: Immunological Phenotypes Associated with Neurodegenerative Disease

contributor:
Miller, Matthew
Biochemistry and Biomedical Sciences

subject:
Neurodegenerative disease
Immunology

abstract:
The etiology of most neurodegenerative diseases remains a mystery. Environmental factors seemingly play an important role in neurodegenerative diseases, as does the immune system. Here, we describe immunological phenotypes associated with the neurodegenerative diseases AOA2 and ALS.
	During CSR, B-cells and neurons share a preferred pathway for DNA repair, NHEJ. SETX, the gene implicated in AOA2, has been implicated in the DDR. In SETX-deficient conditions, B-cells exhibit a defect in IgA class-switching as a result of impaired NHEJ and enhanced alternate-end joining, a slower process with higher mutational burden. These results suggest that neurons in SETX-deficient patients may also demonstrate defects in DNA repair, leaving them more susceptible to death. Further, IgA plays an important role in both protection from infections and as an anti-inflammatory mediator at mucosal surfaces. Defects in IgA class switching might lead to immune dysregulation in AOA2, similar to that observed in other neurodegenerative diseases.
	Viral infections have been associated with several neurodegenerative diseases, including ALS. However, a causal role for viruses in the etiology of ALS has never been established. Common viral infections can impact immune cell phenotypes within the CNS. Microglia are the primary immune cell of the CNS and are able to respond to subtle changes in the microenvironment. Microglia have neurotoxic properties upon hyper-activation. Influenza infection of SOD1G93A mice accelerated ALS disease progression and reduced overall survival. Exacerbated microgliosis was evident within the spinal cords of infected mice. Thus, the immune response stimulated by viral infections may result in toxic microgliosis that accelerates the progression of ALS.
	Together, this body of work describes a series of novel immunological abnormalities associated with AOA2 and ALS4. A deeper understanding of the role played by the immune system in patients with neurodegenerative disorders may unveil new targets for future therapies.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: The causes of most neurodegenerative diseases remain poorly understood. These diseases are highly complex, as they are influenced by both genetics and the environment and involve many different cell types. However, neurodegenerative diseases also share common hallmarks. The immune system is known to behave abnormally in several neurodegenerative diseases. Therefore, we set out to study the involvement of the immune system in two related neurodegenerative diseases, ataxia with oculomotor apraxia type 2 (AOA2) and amyotrophic lateral sclerosis (ALS). We demonstrate that AOA2-like mutations in senataxin (SETX) affect the formation of specific antibodies due to problems repairing broken DNA. We also find that viral infections activate immune cells within the spinal cord which can promote ALS progression. Taken together, this body of work suggests that the immune system plays an important role in AOA2 and ALS, and that drugs that prevent abnormal immune responses might help to treat these diseases.


title: Chemistry of Manganese Complexes Containing Metal–Carbon, Metal–Silicon, and Metal–Hydride Linkages

contributor:
Emslie, David J. H.
Chemistry

subject: Manganese, Silyl, Silylene, Silene, Organosilyl, Organometallic, Alkyl, Hydride

abstract:
The solid state structures and the physical, solution magnetic, solid state magnetic, and spectroscopic (NMR and UV/Vis) properties of a range of oxygen- and nitrogen-free dialkylmanganese(II) complexes are reported, and the solution reactivity of these complexes towards H2 and ZnEt2 is described. The dialkyl compounds investigated are [{Mn(μ-CH2SiMe3)2}∞] (1), [{Mn(CH2CMe3)(μ-CH2CMe3)2}2{Mn(μ-CH2CMe3)2Mn}] (2), [Mn(CH2SiMe3)2(dmpe)] (3) (dmpe = 1,2-bis(dimethylphosphino)ethane), [{Mn(CH2CMe3)2(μ-dmpe)}2] (4), [{Mn(CH2SiMe3)(μ-CH2SiMe3)}2(μ-dmpe)] (5), [{Mn(CH2CMe3)(μ-CH2CMe3)}2(μ-dmpe)] (6), [{Mn(CH2SiMe3)(μ-CH2SiMe3)}2(μ-dmpm)] (7) (dmpm = bis(dimethylphosphino)methane), and [{Mn(CH2CMe3)(μ-CH2CMe3)}2(μ-dmpm)] (8). Syntheses for 1-4 have previously been published, but the solid state structures and most properties of 2-4 had not been described. Compounds 5 and 6, with a 1:2 dmpe:Mn ratio, were prepared by reaction of 3 and 4 with base-free 1 and 2, respectively. Compounds 7 and 8 were accessed by reaction of 1 and 2 with 0.5 or more equivalents of dmpm per manganese atom. An X-ray structure of 2 revealed a tetrametallic structure with two terminal and six bridging alkyl groups. In the solid state, bis(phosphine)-coordinated 3-8 adopted three distinct structural types: (a) monometallic [LMnR2], (b) dimetallic [R2Mn(μ-L)2MnR2], and (c) dimetallic [{RMn(μ-R)}2(μ-L)] (L = dmpe or dmpm). Compound 3 exhibited particularly desirable properties for an ALD or CVD precursor, melting at 62-63 °C, subliming at 60 °C (5 mTorr), and showing negligible decomposition after 24 h at 120 °C. Comparison of variable temperature solution and solid state magnetic data provided insight into the solution structures of 2-8. Solution reactions of 1-8 with H2 yielded manganese metal, demonstrating the thermodynamic feasibility of the key reaction steps required for manganese(II) dialkyl complexes to serve, in combination with H2, as precursors for metal ALD or pulsed-CVD. By contrast, the solution reactions of 1-8 with ZnEt2 yielded a zinc-manganese alloy with an approximate 1:1 Zn:Mn ratio.
Wilkinson’s manganese(I) ethylene hydride complex trans-[(dmpe)2MnH(C2H4)] (10) can react as a source of a low-coordinate manganese(I) ethyl complex. This is illustrated in the reactivity of 10 towards a variety of reagents in this work (vide infra). The proposed low-coordinate intermediate, [(dmpe)2MnEt] (13), was not observed spectroscopically, but could be trapped using isonitrile ligands; reaction of 10 with CNR (R = tBu, o-xylyl) afforded the manganese(I) ethyl complexes [(dmpe)2MnEt(CNR)] (14a: R = tBu, 14b: R = o-xylyl). Ethyl complex 14a did not react further with CNtBu at 80 °C. By contrast, complex 14b reacted with excess o-xylyl isonitrile to form 1,1 insertion products, including the iminoacyl complex [(dmpe)Mn(CNXyl)3{C(=NXyl)CEt(=NXyl)}] (15, Xyl = o-xylyl). Complexes 14a-b and 15, as well as previously reported 10, were crystallographically characterized, and DFT calculations were employed to probe the accessibility of cis ethylene hydride and ethyl isomers of 10.
Reaction of the ethylene hydride complex trans-[(dmpe)2MnH(C2H4)] (10) with H2SiEt2 at 20 °C afforded the silylene hydride [(dmpe)2MnH(=SiEt2)] (16Et2) as the trans isomer. By contrast, reaction of 10 with H2SiPh2 at 60 °C afforded [(dmpe)2MnH(=SiPh2)] (16Ph2) as a mixture of the cis (major) and trans (minor) isomers, featuring a Mn–H–Si interaction in the former. The reaction to form 16Ph2 also yielded [(dmpe)2MnH2(SiHPh2)] (18Ph2); [(dmpe)2MnH2(SiHR2)] {R = Et (18Et2) and Ph (18Ph2)} were accessed cleanly by reaction of 16R2 with H2. Both 16Et2 and 16Ph2 engaged in unique reactivity with ethylene, generating the silene hydride complexes cis-[(dmpe)2MnH(R2Si=CHMe)] {R = Et (19Et2) and Ph (19Ph2)}. Compounds trans-16Et2, cis-16Ph2, and 19Ph2 were crystallographically characterized, and bonding in 16Et2 and 19Et2 was probed computationally.
trans-[(dmpe)2MnH(C2H4)] (10) reacted with primary hydrosilanes H3SiR (R = Ph, nBu) at 60 °C to afford ethane and the manganese disilyl hydride complexes [(dmpe)2MnH(SiH2R)2] (20Ph: R = Ph, 20Bu: R = nBu). 20R reacted with ethylene to form silene hydride complexes [(dmpe)2MnH(RHSi=CHMe)] (19Ph,H: R = Ph, 19Bu,H: R = nBu). Compounds 19R,H reacted with a second equivalent of ethylene to generate [(dmpe)2MnH(REtSi=CHMe)] (19Ph,Et: R = Ph, 19Bu,Et: R = nBu), resulting from apparent ethylene insertion into the silene Si–H bond. Furthermore, in the absence of ethylene, silene complex 19Bu,H slowly isomerized to the silylene hydride complex [(dmpe)2MnH(=SiEtnBu)] (16Bu,Et). Reactions of 20R with ethylene likely proceed via low-coordinate silyl {[(dmpe)2Mn(SiH2R)] (17Ph: R = Ph, 17Bu: R = nBu)} or silylene-hydride {[(dmpe)2MnH(=SiHR)] (16Ph,H: R = Ph, 16Bu,H: R = nBu)} intermediates accessed from 20R by H3SiR elimination. DFT calculations and high temperature NMR spectra support the accessibility of these intermediates, and reactions of 20R with isonitriles or N-heterocyclic carbenes yielded the silyl isonitrile complexes [(dmpe)2Mn(SiH2R)(CNR')] (21a-d: R = Ph or nBu; R' = o-xylyl or tBu), and NHC-stabilized silylene-hydride complexes [(dmpe)2MnH{=SiHR(NHC)}] (22a-d: R = Ph or nBu; NHC = 1,3-diisopropylimidazolin-2-ylidene or 1,3,4,5-tetramethyl-4-imidazolin-2-ylidene), respectively, all of which were crystallographically characterized.
Manganese silyl dihydride complexes [(dmpe)2MnH2(SiHR2)] {R = Ph (18Ph2) or Et (18Et2)} and [(dmpe)2MnH2(SiH2R)] {R = Ph (18Ph) or nBu (18Bu)} were generated by exposure of silylene hydride complexes, [(dmpe)2MnH(=SiR2)] (16R2), and disilyl hydride complexes, [(dmpe)2MnH(SiH2R)2] (20R), respectively, to H2 at room temperature. In solution, 18R and 18R2 exist as an equilibrium mixture of a central isomer with a meridional H–Si–H arrangement of the silyl and hydride ligands {this isomer may be considered to contain an η3-coordinated silicate (H2SiR3–) anion}, and a transHSi isomer with trans-disposed hydride and nonclassical hydrosilane ligands (the latter is the result of significant but incomplete hydrosilane oxidative addition). Additionally, DFT calculations indicate the thermodynamic accessibility of lateralH2 and transH2 isomers with cis- and trans-disposed silyl and dihydrogen ligands, respectively. Compounds 18Ph2 and 18Ph crystallized as the central isomer, whereas 18Bu crystallized as the transHSi isomer. Bonding in the central and transHSi isomers of 18R and 18R2 was further investigated through 29Si_edited 1H–1H COSY solution NMR experiments to determine both the sign and magnitude of J29Si,1H coupling (negative and positive values of J29Si,1H are indicative of dominant 1-bond and 2-bond coupling, respectively). These experiments afforded J29Si,1H coupling constants of –47 Hz for η3-(H2SiR3) in the central isomer of 18Et2 (calcd. –40 to –47 for 18R and 18R2), –38 to –54 Hz for η2-(R3Si–H) in the transHSi isomer of 18R and 18R2 (calcd. –26 to –47 Hz), and 5 to 9 Hz for the terminal manganese hydride ligand in the transHSi isomer of 18Et2, 18Ph, and 18Bu (calcd. 12 to 14 Hz for 18R and 18R2), experimentally supporting the nonclassical nature of bonding in the central and transHSi isomers.
Exposure of disilyl hydride complexes 20R to diisopropylcarbodiimide {C(NiPr)2} afforded manganese(I) amidinylsilyl complexes [(dmpe)2Mn{κ2-SiHR(NiPrCHNiPr)}] {R = Ph (25Ph,H) or nBu (25Bu,H)}. DFT calculations and analysis of XRD bond metrics suggest that the structure of 25R,H involves a contribution from a resonance structure featuring a neutral base-stabilized silylene and an anionic amido donor on manganese. Reactions of 20R, as well as the silylene hydride complex 16Et2, with CO2 yielded the manganese(I) formate complex trans-[(dmpe)2Mn(CO)(κ1-O2CH)] (26), with a polysiloxane byproduct. Compound 26 was found to undergo reversible CO2 elimination at room temperature, and was only stable under an atmosphere of CO2. Complexes 25R,H and 26 were crystallographically characterized.
Silyl, silylene, and silene complexes in this work were accessed via reactions of [(dmpe)2MnH(C2H4)] (10) with hydrosilanes, in some cases followed by ethylene. Therefore, ethylene (C2H4 and C2D4) hydrosilylation was investigated using [(dmpe)2MnH(C2H4)] (10) as a pre-catalyst, resulting in stepwise conversion of primary to secondary to tertiary hydrosilanes. Various catalytically active manganese-containing species were observed during catalysis, including silylene and silene complexes, and a catalytic cycle is proposed. The proposed catalytic cycle is unusual due to the involvement of silylene hydride and silene hydride complexes, potentially as on-cycle species.
The reaction of [(dmpe)2MnH(C2H4)] (10) with H2 at 60 °C afforded ethane and the dihydrogen hydride complex [(dmpe)2MnH(H2)] (11), which has previously been prepared by an alternative route. Complex 10 reacted with hydroborane reagents 9-BBN or HBMes2 at 60 °C to afford EtBR2 and Mn(I) borohydride complexes [(dmpe)2Mn(μ-H)2BR2] (29: R2 = C8H14, 30: R = Mes); two intermediates were observed in each of these reactions. Deuterium labelling experiments using the deuterated hydroborane DBMes2 suggest that this reaction proceeds via the 5-coordinate ethyl isomer of 10; [(dmpe)2MnEt] (13). By contrast, exposure of 10 to BH3∙NMe3 required a higher temperature (90 °C) to yield [(dmpe)2Mn(μ-H)2BH2] (28), and ethylene was formed as the reaction byproduct; this reaction presumably proceeded by ethylene substitution. Deuterium incorporation into both the MnH and BH environments of 28 was observed under an atmosphere of D2 at 90 °C. Reactions of 10 with free dmpe yielded ethylene and a mixture of [{(dmpe)2MnH}2(μ-dmpe)] (31) and [(dmpe)2MnH(κ1-dmpe)] (32), which could be isolated by washing/recrystallization or sublimation, respectively. Similar reactivity was observed between 10 and HPPh2, which afforded ethylene and [(dmpe)2MnH(HPPh2)] (33) at 90 °C. Exposure of 10 to HSnPh3 yielded the manganese(II) stannyl hydride complex [(dmpe)2MnH(SnPh3)] (34) along with ethylene and, presumably, additional unidentified products. However, the mechanism for formation of 34 is unclear, it could not be isolated in pure form due to decomposition to form various species including SnPh4, and the mechanism of the decomposition process remains obscure. Previously reported complex 11, along with new complexes 28-31 and 33-34, were crystallographically characterized.
This work provides valuable insights to unusual metal–ligand bonding motifs and reactions, and as such contributes to the fundamental understanding of organometallic chemistry.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)

abstract: The focus of this work is the synthesis and investigation of manganese-containing complexes with Mn–P, Mn–C, Mn–H, and/or Mn–Si linkages. Many of these complexes feature unusual bonding motifs, including the first group 7 complexes bearing an unstabilized silylene (:SiR2) ligand and the first 1st row transition metal complexes bearing an unstabilized silene (R2Si=CR2) ligand. Variable temperature Nuclear Magnetic Resonance (NMR) spectroscopy and X-ray crystallography were employed to investigate the structures of these complexes, while Density Functional Theory (DFT) calculations and trapping experiments were employed to understand the mechanisms for various unusual chemical transformations. Some of the complexes were evaluated for activity towards catalytic hydrosilylation of ethylene. This work provides valuable insights to unusual metal–ligand bonding motifs and reactions, and as such contributes to the fundamental understanding of organometallic chemistry.


title: HYPERGLYCEMIA AND COMPONENTS OF AN OBESOGENIC DIET WORSEN THE OUTCOMES OF ENTERIC INFECTION

contributor:
Schertzer, Jonathan
Biochemistry and Biomedical Sciences

subject: hyperglycemia, obesity, diabetes, enteric infection

abstract: Obesity is a major predictor for type 2 diabetes. The etiology and comorbidities of these two diseases are associated. Diabetics are twice as likely to contract any type of infection and at greater risk of worse clinical outcomes to infection. However, the individual effects of diet, glycemia and obesity on risk and severity of enteric infection has not been elucidated. Here we show that high blood glucose (i.e. hyperglycemia), independent of obesity, is sufficient to promote mortality during infection with Citrobacter rodentium, a diarrhea-causing pathogen in mice. Mortality was caused by dehydration as a result of excessive Wnt/β-catenin signalling. Our findings highlight the importance of glucose lowering and fluid therapy as opposed to immunological dysfunction, gut barrier defects or bacteraemia as modifiers of outcomes from enteric infection during diabetes. Future work should develop a more comprehensive understanding of the molecular changes that connect hyperglycemia, Wnt/β-catenin pathway and fluid balance during infection. We used the most common model to cause diet-induced obesity in mice to study another enteric pathogen. We showed that long- and short-term high-fat diet (HFD) feeding promoted the colonization and expansion of adherent-invasive Escherichia coli. Higher pathogen burdens in the intestinal tissues and feces were detected in diet-induced obese mice, which coincided with increased distal gut pathology. Initiating the diet one day prior or after infection was sufficient to promote the expansion of adherent-invasive E. coli in the absence of robust weight gain implicating components of diet as a major determinant of pathogen burden. We isolated the dietary factor and found that low fibre content of the high-fat diet was partially responsible for the increased intestinal pathogen burden. Future work should determine how lower fibre alters host and bacterial metabolism in order to promote overgrowth of adherent-invasive E. coli in the gut.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Obesity and diabetes are major public health issues that are connected in many ways, including how diet changes glucose metabolism. Diabetics have a higher risk of contracting infections and also have worse outcomes from infections. It was unknown what factors of obesity or diabetes influence how the immune system combats bacterial infections. The gut is an important site as it is where diet, the immune system, and metabolism all directly interact. We discovered that high blood sugar was associated with death related to dehydration in diabetic, but not necessarily obese mice infected with a diarrhea causing bacteria. Diet-induced obesity in mice infected with bacteria associated with Crohn's disease, showed an overgrowth of bacteria and worse intestinal damage. We isolated the key dietary factor responsible, which was low fibre rather than high fat or sugar. Even one day of lower dietary fibre promoted overgrowth of infectious bacteria in the gut.


title: Physical activity and cardiovascular health indicators during early childhood

title: Physical activity and cardiovascular health in preschoolers

contributor:
MacDonald, Maureen J.
Kinesiology

subject:
child
physical activity
preschooler
accelerometry
cardiovascular health
vascular stiffness
fitness
blood pressure
heart rate
autonomic function
primordial prevention
guidelines
arterial wall motion

abstract: Cardiovascular disease begins to develop in childhood. Physical activity positively impacts cardiovascular health and lowers cardiovascular disease risk in school-aged children and adults; however, there is insufficient evidence to determine the effects of physical activity on cardiovascular health during early childhood. The specific dose of physical activity required for favourable cardiovascular health in this age group is also unknown. The purpose of this thesis was to explore the relationships between physical activity and cardiovascular health indicators during early childhood. In the first study, we found that physical activity engagement has beneficial effects on cardiovascular fitness, blood pressure, autonomic function, and arterial stiffness during early childhood. We then determined in the second study that to avoid unfavourable cardiovascular health, preschool-aged children should engage in at least 240 minutes of activity at any intensity, 80 minutes of moderate-to-vigorous physical activity, or 8700 steps per day. Finally, in the third study we evaluated a novel technique for examining arterial wall properties, carotid artery longitudinal wall motion, and determined that it was weakly associated with an established indicator of arterial stiffness (pulse wave velocity) in early childhood. These findings highlight that the benefits of physical activity on cardiovascular health begin in early childhood and the minimal amount of activity to avoid unfavourable cardiovascular health is higher than current recommendations. For the most part, physical activity benefited boys and girls similarly, although it is unclear if the physical activity targets apply equally to boys. We also determined that carotid artery longitudinal wall motion may not be an indicator of arterial stiffness in young children. Future studies should determine if the favourable effects of physical activity on cardiovascular health during early childhood carry over to later years and if achieving the physical activity targets determined in this thesis are associated with additional health benefits.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Heart disease develops slowly over time, starting in childhood. This thesis explored if physical activity can begin to prevent heart disease even in preschoolers, and how much physical activity preschoolers need in order to keep their hearts and blood vessels healthy. We found that preschool-aged children who were more active had better heart health, including better blood vessel health and higher fitness. While all activity was good, more intense, moderate-to-vigorous physical activity (sometimes called energetic play) was more beneficial and slowed down the stiffening of their blood vessels as the children grew. We determined that preschool-aged children should engage in at least 4 hours of physical activity at any intensity or 80 minutes of moderate-to-vigorous physical activity every day to avoid poor heart health. The findings in this thesis highlight the importance of regular physical activity participation to promote heart health even in preschool-aged children.


title: Examining the Housing Experiences of Refugee Claimant Families in the Greater Toronto and Hamilton Area: Service Providers’ Perspectives

contributor:
Zhou, Rachel
Social Work

subject:
Refugee Claimants
Refugees
Housing
Homelessness
Health
Social Determinants of Health

abstract: Housing is a key social determinant of health. Further to this, my research will show that it is through housing that all other health determinants are fully actualized. For refugee claimant (RC) families, housing is the most immediate and pressing need upon their arrival in Canada. The objective of this exploratory qualitative study is to examine the housing experiences of refugee claimant (RC) families in the Greater Toronto and Hamilton Area (GTHA) and its impact on the health, well-being, settlement and integration of this population from the perspectives of services providers. Given the increasing inflows of asylum seekers in Canada over the past few years, there is an urgent need to examine their housing experiences and subsequent impacts on health and well-being. Using purposive sampling, seven service providers from five different refugee centres and family shelters in the GTHA were recruited. Individual, semi-structured interviews were conducted, recorded, transcribed, and then analyzed thematically. Findings demonstrate that accessing both emergency and permanent housing upon arrival is particularly difficult for RCs, given that the demand for housing continues to surpass availability in the emergency shelter system and private housing market in the GTHA. In their search for permanent housing, many RCs rely on the private housing market, where discrimination and affordability are common barriers. With an uneven and difficult trajectory towards housing access, many RCs face health issues associated with stress, poverty, and homelessness, which disrupt their settlement and integration in Canada. This research concludes by offering recommendations for policy and program level changes to improve refugee housing access in the GTHA. These recommendations include increasing service provision capacity in shelters, expanding transitional housing options for RCs, increasing investments in subsidized housing, limiting government involvement in REITS and increasing incentives to build more subsidized housing.

abstract: Thesis

abstract: Master of Social Work (MSW)


title: Estimating Proportions by Group Retesting with Unequal Group Sizes at Each Stage

contributor:
Walter, Stephen
Statistics

subject:
proportion estimation
group testing
retesting

abstract:
Group testing is a procedure that splits samples into multiple groups based on some specific grouping criterion and then tests each group. It is usually used in identifying affected individuals or estimating the population proportion of affected individuals. Improving precision of group testing and saving cost of experiment are two crucial tasks for investigators. Cost-efficiency is a ratio of precision to cost; hence improving cost-efficiency is as crucial as improvement of precision and cost saving. In this thesis, retesting will be considered as a method to improve precision and cost-efficiency, and save cost. Retesting is an extension of group testing. It uses two or more group testing stages, and testing original samples in all of the stages. Hepworth and Watson (2015) proposed a two-stage group testing procedure where two stages have equal group sizes, and the number of groups of the second stage is based on the number of positive
groups in the first stage. In this thesis, our main goal is estimating a proportion p under the circumstance of unequal group sizes in two stages, and discovering the most cost-efficient experiment design. Analytical solutions of precision will be provided; we will use these analytical solutions with simulations to analyse some experimental designs, and discover whether doing one group testing only is precise enough or not
and if it is worth retesting for each design. In the end, we will combine all these analyses and identify the optimal experiment design.

abstract: Thesis

abstract: Master of Science (MSc)