title: A Diffusion Theory Model Of Spatially Resolved Fluorescence from Depth Dependent Fluorophore Concentrations

contributor:
Farrell, Dr. T.J.
Medical Physics

subject:
diffusion theory model
spatially resolved fluorescence
depth dependent fluorophore
concentrations

abstract: Photodynamic therapy (PDT) currently utilizes drug and light doses which are primarily based on clinical experience. This can lead to a dose which is not sufficient to destroy the entire tumor, or alternatively, it can lead to the undesirable destruction of healthy tissue around the treatment area. PDT of topically applied photosensitizers is one focus of this research. This concerns the diffusion of an externally applied drug into the tissue, as well as its subsequent destruction during the irradiation procedure. This work involves the non-invasive measurement of the inherent fluorescence of the photosensitizer, allowing the determination of the concentration and distribution of drug within the tissue, and thus optimizing this treatment. To do this, one must be able to describe the propagation of light within the tissue. Consequently, a photon diffusion model has been developed to calculate the steady-state spatially resolved fluorescence from a pencil beam excitation in a depth dependent medium. The validity of this model was then verified by comparison with Monte Carlo simulations and measurements made on phantoms with optical properties similar to those of human tissue. Theoretical conditions were then explored, and potential uses of the model were demonstrated.

abstract: Thesis

abstract: Master of Science (MS)


title: CLOSTRIDIUM DIFFICILE INFECTION AND COLONIZATION IN PAEDIATRIC ONCOLOGY PATIENTS

contributor:
Mertz, Dominik
Health Research Methodology

subject:
Clostridium difficile
Oncology
Pediatrics

abstract:
Clostridium difficile infection (CDI) is the most common hospital-associated infection and is linked to increased morbidity, mortality and costs. Asymptomatically colonized patients may act as an infection reservoir and their numbers have been found to exceed symptomatic CDI cases. In addition to higher rates of CDI among children hospitalized with cancer compared to those without an oncologic diagnosis, these patients also experience substantially higher C. difficile colonization rates. However, the current published literature does not adequately address the natural history of C. difficile colonization in this population, in terms of who is at greatest risk for developing colonization, duration of colonization, or progression to CDI.

A retrospective longitudinal cohort study of pediatric oncology patients admitted to the oncology ward at McMaster Children’s Hospital (MCH) was conducted from September 1 2016 to February 28 2018. Patients who were routinely screened for antibiotic-resistant organisms (AROs) upon admission per hospital policies had their stored samples subsequently tested for asymptomatic carriage of C. difficile. A retrospective analysis was completed to determine predictors of colonization and risk factors for progression to subsequent CDI.

We observed a lower colonization rate than other studies have reported in the literature. Duration of colonization was likely brief and none of the colonized patients subsequently developed CDI. There were no statistically significantly associated predictors for asymptomatic colonization when colonized patients were compared to those who were never colonized.

abstract: Thesis

abstract: Master of Science (MSc)


title: A Remote Electro-Optical Technique for Monitoring Singlet Oxygen Generation During Photodynamic Therapy

title: Remote Electro-Optical Detection of Singlet Oxygen in Vivo

contributor:
Patterson, M. S.
Health and Radiation Physics

subject:
remote electro-optical technique
singlet oxygen generation
photodynamic therapy
radiation physics
cancer
cancer treatment

abstract: Photodynamic therapy (PDT) is a form of local cancer treatment in which cell death is caused by photochemical reactions involving an exogenous photosensitizer. The photosensitizer, which is preferentially retained in malignant tissues, is photoactivated and cell death results from the generation of reactive products -most likely excited molecular (singlet) oxygen. The development of in vivo PDT dosimetry would be greatly aided by the ability to directly measure the local concentration of this product by non-invasive means. In condensed media singlet oxygen will, with some small probability, undergo a radiative transition to the ground state with emission at 1270 nm. This infrared phosphorescence may provide a means for monitoring the production of singlet oxygen in vivo. Unfortunately the background infrared fluorescence observed from tissue may be many times the expected magnitude of the 1270 nm phosphorescence, even within the bandwidth encompassing the peak. The principal aim of this project was the design of a system optimized for the in vivo detection of the singlet oxygen emission. The system makes use of the most sensitive commercially available detector and uses phase sensitive detection to discriminate against infrared fluorescence. The system's performance matched theoretical expectations for the photosensitizer Photofrin II in aqueous and methanol solutions. However, a discrepancy in the observed and theoretical values was noted for aluminum chlorosulphonated phthalocyanine suggesting a deviation from simple first order kinetics. Singlet oxygen phosphorescence was not observed during PDT of cell suspensions or mouse tumours even though considerable cell death and tumour necrosis were observed. The most likely explanation of this failure is that, due to quenching by biomolecules, the lifetime of singlet oxygen in cells or tissue is much lower than in solution so that the probability of emission is reduced accordingly. Quantitative calibration of the system yielded a lower limit of approximately 0.1 us on the singlet oxygen lifetime in tissue. This suggests that singlet oxygen is generated in a protein environment.

abstract: Thesis

abstract: Master of Science (MS)


title: The Efficiency of Acute Care Hospitals in Canada

contributor:
Grignon, Michel
Health Research Methodology

subject: Efficiency, Acute care, Hospital

abstract:
Improving hospital efficiency is a critical concern for health care managers and policy makers. Hospital technical efficiency is measured as the ratio of what quantity and quality of care is produced to what could be produced given the level of resources available to the hospital (its budget). What a hospital should produce given the resources at its disposal is called the “production frontier”. In order to improve hospital performance, health policy makers need knowledge and information about how well the hospitals they fund are utilizing the resources they receive. Data Envelopment Analysis, a non-parametric technique, is applied to administrative data on hospitals in Canada to produce the “technical frontier” and get insight into the variation of technical efficiency of acute hospitals at the Pan-Canadian level (except for the province of Quebec, which does not report its data on hospitals in a way that would make them comparable to the rest of Canada). DEA is preferred to the alternative method of stochastic frontier for the following reasons: DEA does not require to impose a specification on the production function of hospitals (for which theory is clearly lacking), and it allows the analyst to estimate a multi-output frontier (a stochastic frontier would have to weight arbitrarily the value of quantity versus that of quality of care in hospitals, whereas the DEA approach generates these weights from the data). Efficiency scores are serially de-correlated using a bootstrap technique and then entered as the dependent variable in regressions to identify the main factors of efficiency or inefficiency.
    Specifically, this thesis aims to: 1) estimate the level of technical efficiency of acute inpatient care in 35 teaching hospitals, 54 large hospitals and 90 medium-size hospitals respectively in Canada and identify the potential factors that have influence on technical efficiency; 2) uncover and measure the existence of possible spatial spillovers of hospital efficiency in Canada and examine its potential determinants while taking into account the interaction between hospitals by means of spatial regression; and 3) examine the technical and scale efficiency of the 229 small and rural hospitals across Canada (outside Quebec), as well as estimate the impact of institutional and contextual variables on hospital technical and scale efficiency respectively.
    The major findings are: 1) hospital output (combination of number and quality of stays; quality being measured as the inverse of in-hospital mortality) in Canada could be increased by 24 percent with the same resources by eliminating inefficiency. Highly efficient teaching hospitals benefit from producing care under favourable environments. Higher efficiency could be achieved by increasing cooperation within the health system and making more post- acute care beds available to both large and medium hospitals; 2) There is a substantial and significantly positive spatial spillover effect on the efficiency of acute inpatient care (elasticity of 0.3): Canadian hospitals are clearly complements to each other and work in networks much more than in competition. The hospital size (the number of beds), the percent of transfers between acute hospitals, and the percent of patient transfers to home care are the main drivers of efficiency among acute hospitals in Canada while controlling of the dependence between hospitals; and 3) Among small hospitals, the average output orientation technical efficiency on all types of services is 54% at the current input-output mix. To improve their technical efficiency, small hospitals should provide with more home care facilities to discharge their patients to (so-called Alternative Level of Care patients) and strengthen their cooperation with larger, urban hospitals. Small hospitals are scale inefficient, specifically, rural hospitals could reduce their size by 34% on average (around 6 acute beds) to achieve the optimal size. The study also found that the spending on diagnosis tests and the nursing as the percentages of total hospital spending (cost shares) are positively and significantly related to the scale efficiency.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract:
A hospital is technically efficient if it uses its resources (its budget) to get the most in terms of quantity (number of stays) and quality of care it can. A hospital can be more or less technically efficient for reasons independent of its control (typically, because of the environment in which the hospital operates) and efficiency is a value-neutral measure. This thesis aims to: 1) estimate the technical efficiency of acute inpatient care in Canada and identify the potential factors that influence the level of efficiency achieved by a given hospital; 2) uncover the existence of possible geographic clusters of efficiency (hospitals that are close geographically are also close in the efficiency scale, something called spatial spillovers in the literature) in Canada.; and 3) examine the role that size plays in the variation of technical efficiency among small and rural hospitals across Canada.
    The major findings are: 1) hospital output could be increased by 24 percent with the same resources by eliminating technical inefficiency; 2) There is a substantial and significantly positive spatial spillover effect on the efficiency of acute inpatient care: being close to an efficient hospital increases the efficiency score of a hospital, everything else being the same; and 3) The level of technical efficiency of small and rural hospitals across Canada is low overall and, perhaps surprisingly, larger rural hospitals are among the least efficient: among small hospitals, scale does not yield economies of resources.


title: Novel Reactions of Nickel (II) - Oligopeptide Complexes with Dioxygen Species

contributor:
Nieboer, Evert
Biochemistry

subject: Nickel, nickel II, oligopeptide, dioxygen species

abstract:
The ability of simple oligopeptide complexes of nickel (II) to
react with various dioxygen intermediates was investigated. Under
physiological conditions, nickel (II)-histidine-containing
oligopeptides were found to dismutate superoxide anions and
disproportionate hydrogen peroxide. In the latter process,
chemiluminescence was generated and a strongly oxidizing intermediate
was detected capable of oxidizing uric acid, hydroxylating p-nitrophenol,
and damaging 2-deoxy-D-ribose. The generation of this
reactive intermediate likely occurs without the involvement of free
hydroxyl radicals derived from Haber-Weiss or Fenton-type reactions.
In addition, the Ni(II) complex of glycylglycyl-L-histidine (GGH) was
found to react with mollecular oxygen resulting in the oxidation of the
ligand. An attempt was made to relate these reactions to the
involvement: of the nickel(III)/(II) redox couple which was shown to
exist under physiological conditions. Similar reactivity was observed
for non-histidine-containing oligopeptides but higher pH values were
required.
The oligopeptides used not only represent biologically relevant
ligands but: the histidine containing oligopeptides mimics the specific
copper(II)/nickel(II) binding and transport site of human serum
albumin. The observations made in this study suggest some novel
mechanism for the deleterious effects associated with excessive lifelong
exposure to nickel compounds, especially in relation to cancer of
the respiratory tract.

abstract: Thesis

abstract: Master of Science (MS)


title: Dosimetry of Skin-Contact Exposure to Tritium Gas Contaminated Surfaces

title: Tritium Skin-Contact Dosimetry

contributor:
Horvath, F.
Trivedi, A.
Webber, C. E.
Health and Radiation Physics

subject:
dosimetry
skin-contact exposure
tritium gas

abstract: The radiological hazards from tritium are usually associated with exposure to tritium oxide either by inhalation, ingestion or permeation through skin. However, exposure from skin-contact with tritium gas contaminated surfaces represents a different radiological hazard in tritium removal facilities and future fusion power plants. Previous experiments on humans by Eakins et al. (8), and more recent experiments on hairless rats at Chalk River Laboratories have shown that when a tritium gas-contaminated surface is brought into contact with intact skin, high concentrations of organically-bound tritium in urine and skin are observed which were not seen from single tritiated water (liquid or vapour form) contamination. The results of the rat experiments, which involved measurements of tritium activity in urine and skin, after contact with contaminated stainless steel, are described. These results are also compared to previous data from human experiments. The effect of various exposure conditions and different contaminated surfaces such as brass, aluminum and glass are analysed and related to the results from contaminated stainless steel exposure. Dosimetric models are being developed in order to improve the basis for dose assessment for this mode of tritium uptake. The presently studied model is explained along with the assumptions and methods involved in its derivation. The features of 'STELLA', the software program used to implement the model, are discussed. The methods used to estimate skin and whole body dose from a model are demonstrated. Finally, some experiments for improving the accuracy of the model are proposed. Briefly, this study compares the results from animal and human experiments as well as different exposure conditions, and determine the range of whole body and skin dose that may be involved from skin-contact intake. This information is essential for regulatory purposes particularly in the derivation of doses for skin-contact contamination.

abstract: Thesis

abstract: Master of Science (MS)


title: The Use of In Vivo X-Ray Fluorescence Measurement in the Analysis of Cadmium Toxicology

contributor:
Chettle, David R.
Physics and Astronomy

subject: cadmium, cadmium toxicology, in vivo, in vivo x-ray, x-ray fluorescence

abstract:
Cadmium (Cd) is a highly toxic metallic element to the human body such that prolonged occupational or environmental exposure produces renal, hepatic, pneumonic, and neurological disorders. Thus, as a consequence it is important to have a way of monitoring cadmium exposure as it has the potential to become an occupational health hazard. The primary uses of this element are in the mining and smelting industry in the manufacture of cadmium alloys and the manufacture of alkaline accumulators.
Since the discovery of X-rays in 1895 by Wilhelm Conrad Roentgen, the science of X-ray analysis has become a cardinal tool in all domains of chemical identification and classification. X-ray fluorescence (XRF) has been shown to be an effectual technique for measuring trace quantities of heavy metals such as lead in various tissues within the body. This thesis stud:r elucidates a means of measuring Cadmium in bone. The study assesses the feasibility and practicality of the polarised XRF and source excited techniques.
In the polarised cadmium concentration measurements, a gain in sensitivity due to improved background characteristics was perused by increasing the x-ray tube operating voltage of the system. It was found that an operating voltage of 175 kV, and a copper filter resulted in a significant gain in sensitivity for which a minimum detection limit (MDL) of 3.5 ± 1.4 ppm was determined with 3 mm of tissue equivalent overlay. Using the source-based technique, a MDL of 3.5 ± 0.2 ppm was estimated for the corresponding tissue equivalent overlay.

abstract: Thesis

abstract: Master of Science (MS)


title: The In Vitro Characterization of a Squamous Carcinoma Cell Line to Combined Treatment with Cisplatin and Ionizing Radiation

title: In Vitro Characterization of Squamous Carcinoma Cells to Cisplatin and Radiation

contributor:
Singh, Gurmit
Physics

subject:
in vitro
cisplatin
ionizing radiation
squamous carcinoma
carcinoma

abstract: It is has been observed in several cell systems that cisplatin can radiosensitize and that the response of cells to combination cisplatin and radiation depends on several factors. These include the radiation dose and drug concentration used, the order in which the two treatments are administered, and the time between their administration. The response of a head and neck squamous carcinoma cell line to combination cisplatin-radiation treatment was examined. The response was found to be additive when cisplatin was given first, regardless of the timing and magnitude of the treatments administered. When cells were treated with radiation first, antagonism was observed for low radiation doses and drug concentrations. The response may be explained by a low radiation dose induction of processes that protect the cell from a second damaging agent, similar to the adaptive response. There is some indication in the literature that cisplatin can preferentially radiosensitize cells that are proficient in certain types of DNA repair. Therefore, the response of a cisplatin-resistant strain of the SCC-25 cell line was also investigated. The cisplatin-resistant cell line was found to be substantially radiosensitized by cisplatin for moderate amounts of radiation and cisplatin. The results are discussed with reference to the current proposed mechanisms for cisplatin-radiation interaction.

abstract: Thesis

abstract: Master of Science (MS)


title: Development and Preliminary Evaluation of Educational Resources About Universal Design for Learning for Speech-Language Pathology Students

contributor:
Campbell, Wenonah
Rehabilitation Science

subject:
universal design for learning
rehabilitation science
diffusion of innovations
knowledge translation
ADDIE model
speech-language pathology

abstract:
BACKGROUND: The mandate to provide inclusive education in Canadian schools means that Speech-Language Pathologists (SLPs) need to be well-versed in frameworks such as Universal Design for Learning (UDL) that support learning among students with diverse backgrounds and abilities. To be responsive, professional graduate programs need resources that support teaching SLP students about UDL.
PURPOSE: 1) To use an instructional design model and Knowledge Translation (KT) theory to develop educational resources about UDL for SLP graduate students; and 2) to assess feasibility of the resources and SLP students’ perceived and actual UDL knowledge change after resource implementation.
METHODS: First, educational resources about UDL were created for SLP students using a process in which the first three phases of the Analysis, Design, Development, Implementation, Evaluation (ADDIE) instructional design model were combined with the Diffusion of Innovations (DOI) KT theory and supported by engagement of key SLP stakeholders. Stakeholder feedback about their involvement in the resource development process was assessed through a focus group and analyzed using conventional content analysis. Next, the last two phases of the ADDIE model were conducted in which the developed resources were implemented and evaluated with 19 SLP students over a three-hour session; resource feasibility and UDL knowledge were measured before and after the session using anonymous, web-based questionnaires.
RESULTS: The novel process for developing resources was deemed suitable for creating high-quality theory-informed resources tailored to SLP students. SLP students perceived the resources to be practical and acceptable. There was a statistically significant improvement in students’ perceived UDL knowledge as well as improvements in actual UDL knowledge.
CONCLUSION: Health educators could consider the described methodology when developing content-specific resources for health professional students. This thesis introduces a new set of resources that could be used to address an important gap in SLP training.

abstract: Thesis

abstract: Master of Science Rehabilitation Science (MSc)

abstract: Inclusive education in which students with diverse abilities learn together is an expectation within Canadian schools. People who work in schools, like Speech-Language Pathologists (SLPs), need to know about frameworks such as Universal Design for Learning (UDL) that identify specific strategies for supporting inclusive education. However, many SLPs do not know about UDL or how to apply this framework when they work with teachers. In this thesis, I used a new resource development process involving a rigorous resource design method with a theory that helps people use new ideas, to make educational resources about UDL for SLP graduate students. Next, I implemented and evaluated the resources with 19 SLP students at McMaster University. Students felt the resources were suitable and taught them new information about UDL. This thesis provides new teaching resources for SLP students to increase their knowledge about UDL and better prepare them for working in schools.


title: Was St. Paul's Bay Disease Endemic Syphilis?

contributor:
Herring, A.
Anthropology

subject:
anthropology
st. paul's bay disease
syphilis
endemic syphilis

abstract:
There is a definite lack of information on treponemal infections in Canada. This thesis attempts to add to the knowledge on treponemal infections from studying outbreaks of the disease from smaller geographic regions of Canada.
The purpose of this thesis is to study an alleged outbreak of syphilis, known as St. Paul's Bay Disease (SPBD) and to learn as much as possible about this disease, including its clinical and epidemiological characteristics, diagnosis and origins. This thesis provides evidence to support the contention that this 18th century outbreak of SPBD was not venereal syphilis, but rather endemic syphilis.
The findings of this study were drawn from multiple lines of qualitative and quantitative evidence. The descriptions of SPBD by the medical practitioners of that time period reflect a high degree of similarity between SPBD and endemic syphilis. These descriptions contain information on the symptoms, method of treatment, method of transmission and diagnosis of SPBD. Furthermore, when SPBD was compared to the Sibbens of Scotland (a confirmed outbreak of endemic syphilis) they were found to be almost indistinguishable. Lastly, the distribution and prevalence of SPBD among the affected populations were found to be more characteristic of endemic syphilis.
It is suggested that future research be carried out in three major areas: the ethnohistory of the various towns in Lower Canada, the origins of SPBD, and lastly, why the disease 'suddenly' disappeared. All of which will bring us one step closer to both understanding this outbreak and the history of treponemal infections in general.

abstract: Thesis

abstract: Master of Arts (MA)


title: Incidence of Diarrhoeal Disease and Associated Morbidity Risk Markers in Port Dickson District, Malaysia

contributor:
Lonergan, Dr. S.C.
Geography

subject:
diarrhoeal disease
morbidity risk markers
port dickson district
malaysia

abstract: Due to the increasingly documented prevalence of diarrhoeal diseases in Malaysia, a number of water-related programmes have been implemented in an attempt to improve health status through the reduction of incidence of waterborne communicable diseases associated with poor public water supplies. The implicit assumption underlying these projects is that the enhancement of the physical infrastructure, and subsequent improvements in the quality of the water supply, will substantially reduce waterrelated disease. This thesis questions the veracity of this hypothesis, and therefore the justifiability of an emphasis upon engineering and urban infrastructural interventions. Research centred upon Port Dickson, a district which typifies existing water and sanitation conditions in much of semi-rural Malaysia. The specific objectives of the thesis were: to determine the measured burden of illness of waterborne disease within the district and to estimate levels of underreporting; to determine morbidity-related factors influencing the decision to seek medical treatment; to provide a demographic profile of the population experiencing diarrhoeal episodes; and to identify risk markers or predictors of morbidity. Burden of illness was measured by health services utilization, while values for underreporting and risk markers were derived from a 268 household diarrhoeal morbidity survey. Diarrhoeal incidence was estimated to be 12-16% annually, much higher than Malaysia's official average. This incorporated a rate of non-reporting of 19~, which was influenced by chronicity, duration and severity of episodes. Individuals found to be most at risk were young children and adults in their child-bearing years, minority racial groups, and those with poor water supply and sanitation infrastructure and inappropriate hygiene habits. While water quality was found to influence diarrhoeal rates, factors in addition to infrastructure - partially hygiene - were shown to play a greater role. Thus, it is suggested that the impact of water and sanitation improvement projects would likely be minimal, unless accompanied by complementary behavioural education programmes. The spatial bias of the aforementioned risk factors suggests a need to refocus intervention initiatives upon rural areas.

abstract: Thesis

abstract: Master of Arts (MA)


title: An Examination of Cross-Resistance to Photodynamic Therapy and Ultraviolet Light in Rodent Cells using a Viral Capacity Assay

contributor:
Rainbow, Andrew
Biology

subject:
cross-resistance
photodynamic therapy
ultraviolet light
rodent cell
viral capacity assay

abstract:
Photodynamic therapy (PDT) for cancer utilizes the localised delivery of light to activate a photosensitizing drug (such as Photofrin) which is selectively retained by tumour tissues. Although this treatment modality is undergoing clinical trials, the mechanism of PDT cytotoxicity is not fully understood. One approach to understanding the mechanism of action of PDT is to study cell mutants showing alterations in their response to PDT. The capacity of mammalian cells to support virus replication has been used as an assay to compare cellular response to ultraviolet (UV) light and other cytotoxic agents. Cellular capacity has been previously employed to measure cellular recovery
following UV irradiation and to predict the sensitivity of cells to several anticancer drugs. In this work, I have examined the use of the capacity assay to examine the sensitivity of cells to PDT treatment. RIF-1 mouse fibrosarcoma cells and a PDT resistant derivative, RIF-8A; as well as Chinese hamster ovary (CHO) cells and CHOMDR (multi-drug resistant) mutant cells were studied. Consistent with the clonogenic survival of these cells after PDT, the viral capacities of RIF-8A and CHO-MDR cells· were greater than those of RIF-1 and CHO cells respectively following PDT treatment. The capacity assay was also used to examine the relative ability of RIF cells to recover from PDT damage. These capacity experiments show that recovery from PDT damage is greater in RIF-SA cells compared to RIF-1 cells, suggesting that RIF-SA cells have an enhanced repair capacity for PDT damage compared to RIF-1 cells. The response of CHO cells and the RIF cells to ultraviolet (UV) light irradiation was also examined. No difference in the UV sensitivity of CHO-N and CHO-MDR cells was found. However, the RIF-SA cell line showed a cross-resistance to UV. The survival of viral DNA synthesis for UV-irradiated virus was also greater in RIF-SA cells
compared to RIF-1 cells, suggesting that RIF-SA cells have an increased capacity for the repair of UV-induced DNA damage. It is possible that the increased resistance to PDT of RIF-SA may also result from an increased repair of POT-induced DNA damage in RIF-SA cells. The identification and characterization of a POT-sensitive cell mutant was also investigated. The CHO-AUXB1 cell mutant was found to show an increased sensitivity to PDT and UV compared to the CHO-PRO- parent line. This sensitivity of the CHO-AUXB1 mutant may also result from a deficiency in the repair mechanism of PDT-induced and UV-induced damage.

abstract: Thesis

abstract: Master of Science (MS)


title: Boundary Electron Dosimetry: Radiochromic Film Measurement and Monte Carlo Simulation of Electron Absorbed Dose Near Tissue Interfaces

contributor:
Kwok, C.S.
Physics

subject: boundary electron dosimetry, dosimetry, radiochromic film, radiochromic film measurement, monte carlo, monte carlo simulation, electron absorbed dose, tissue interfaces

abstract:
Tissue heterogeneity effects present a major challenge to electron beam
dosimetry in radiotherapy and radiation protection. The perturbation of the
absorbed dose distribution in tissue due to the presence of heterogeneous
material boundaries was investigated in this work. Experiments were
conducted in a tissue-equivalent phantom in order to quantify electron
backscatter from various materials. For these experiments, irradiations were performed using a 6MeV (nominal) electron beam under conditions of one dimensional geometry. Depth-energy degradation of the electron beam provided mean electron energies of 2.3MeV, 1.9MeV, and 1.4MeV at interface locations. Backscatter phenomena were investigated for the following interface geometries: polystyrene/air, polystyrene/cortical-bone-equivalent plastic, polystyrene/copper, and polystyrene/bismuth. Novel radiochromic film dosimetry techniques were developed for these experiments, and the dose and energy response characteristics of GAFChromic Type 37-041 film were investigated. Monte Carlo simulations of the experiments were performed in parallel, using tile ITS TIGER code, and methodologies were developed to determine appropriate input parameters to these simulations. From experimental and Monte Carlo results, the backscatter factor at the interface, its spatial variation with depth, and its dependence on electron energy and scatterer atomic number were investigated.

abstract: Thesis

abstract: Master of Science (MS)


title: A Method for Pixel-By-Pixel Absolute Quantitation in Positron Emission Tomography

contributor:
Nahmias, C.
Physics

subject: pixel, pixel-by-pixel, absolute quantitation, PET, positron emission tomography

abstract:
This study attempts to develop a method for absolute
quantitation in Positron Emission Tomography. This includes the
definition of the dimension and the position of a tumour in the
brain as well as the evaluation of the amount of drug delivered
to the tumour and to surrounding tissues in a pixel-by-pixel way,
from the image. The defined objectives can be achieved using the
calibrated FWHM values of the distribution of events in the tumour
image, versus distance, to determine the dimension and the
position of the tumour. The concentration activity in the tumour
and the tumour-to-nontumour activity ratios can be obtained from
the image, using a modified filter and the calibration of the
tomograph. The colour scale of the image can be expressed in
absolute units (μCi/ml) and the concentration activity can be
evaluated in each pixel of the image or in each volume element of
the body.

abstract: Thesis

abstract: Master of Science (MS)


title: A PRE-CLINICAL MODEL OF GLIOBLASTOMA RECURRENCE TO IDENTIFY PERSONALIZED THERAPEUTIC TARGETS

contributor:
Singh, Sheila Kumari
Biochemistry and Biomedical Sciences

abstract:
Glioblastoma (GBM) is the most common and lethal primary tumour affecting the central nervous system in adults. Despite aggressive, multi-modal treatment consisting of surgical resectioning of the tumour followed by radiotherapy and chemotherapy, GBM remains incurable. Almost all patients experience relapse 7-9 months post-diagnosis and median survival has not extended beyond 15 months over the past decade. Extensive research in the molecular and cellular biology of GBM has revealed extensive inter- and intra-tumoural heterogeneity caused by dysregulation at genomic, epigenomic, transcriptomic and proteomic levels. Although this has led to the identification of molecular targets for therapeutic development, large body of GBM research has focused on the study of primary GBM, with little exploration of the biological landscape of recurrent GBM. Recent genomic studies suggest that recurrent GBM evolves significantly during the course of therapy and represents a distinct biological entity and therefore therapies developed based on primary GBM biology will not present efficacy against recurrent GBM. Thus, I postulate that models that capture the evolution of GBM biology in response to standard-of-care (SoC) chemoradiotherapy will allow for the identification of therapeutic targets specific to recurrent GBM and can be used for personalized medicine.

Here I show the development of an in vitro and in vivo model of GBM recurrence that can be used as a surrogate to identify personalized therapeutic targets for recurrent GBM. We use established cancer stem cell models combined with patient-derived glioblastoma stem cells (GSC) to profile and characterize the evolution of GBM through in vitro and in vivo adapted SoC. Through our in vitro model, I identified that combined chemoradiotherapy leads to increased sphere formation capacity of GBM and the global gene expression profiling of treatment-refractory GBM populations identified a poor-prognostic subtype of GBM. Next, I used patient-derived recurrent GBM to identify tyrosine kinases EphA2 and EphA3 as therapeutic targets in recurrent GBM and developed a bispecific antibody to co-target these receptors for therapeutic benefit. Lastly, I show the establishment of a novel patient-derived xenograft SoC model to profile the clonal evolution of GSCs through therapy. I show that this model can be coupled with multiple technologies, such as single cell RNA-sequencing and cellular DNA barcoding, to characterize the minimal residual cellular populations driving recurrence and identify personalized therapeutic targets for the treatment of GBM recurrence.

Altogether my thesis highlights the importance of developing clinically relevant models of GBM recurrence and using poly-targeting approaches for the treatment of recurrent GBM.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Investigating Disease Experience in Aboriginal Populations in Canada: the 1918 Influenza Pandemic in Berens River and Poplar River, Manitoba

contributor:
Herring, D. A.
Anthropology

subject:
disease experience
aboriginal population
aboriginal
1918 influenza
berens river
poplar river
manitoba
canada

abstract: This research focuses on the 1918-1919 influenza pandemic and its impact on and spread through two Aboriginal communities in Manitoba: Berens River and Poplar River. The mortality experiences these communities had during the 1918 influenza pandemic are used to examine (a) variations in disease experience between communities, (b) factors influencing the spread of influenza in the study communities during the 1918 pandemic, and (c) the usefulness of employing a holistic health model for community level health research. Reconstruction of the epidemic in these two communities is possible through the integration of both qualitative and quantitative data: ethnohistoric information, demographic, mortality, and mobility data, and environmental information. This thesis provides evidence that (1) closely related communities may have significantly different mortality experiences; while Berens River and Poplar River may have shared similar mortality patterns in some years between 1909-1929, the relationship was not predictable since significant differences could occur, as was the case during the 1918 influenza epidemic from which Poplar River did not suffer, and (2) differences in local economic activities were important determinants in the spread of the 1918 influenza epidemic in these two communities. The results of this investigation suggests that although communities share characteristics in common, such as culture and history, and show similarities in mortality experience, in the case of the introduction of a virgin soil epidemic these similarities cannot predict the course of an epidemic. It is argued that the holistic approach to health research provides a useful method investigate this epidemic since the use of epidemiological, ethnohistorical, environmental and historical information were all necessary in order to understand all the factors that contributed the spread of the 1918 flu.

abstract: Thesis

abstract: Master of Arts (MA)


contributor:
Becker, Suzanna
Computer Science

subject:
multi-resolution mix
principal component

abstract: The main contribution of this thesis is a new method of image compression based on a recently developed adaptive transform called Mixtures of Principal Components (MPC). Our multi-resolution extension of MPC-called Multi-Resolution Mixtures of Principal Components (MR-MPC) compresses and decompresses images in stages. The first stage processes the original images at very low resolution and is followed by stages that process the encoding errors of the previous stages at incrementally higher resolutions. To evaluate our multi-resolution extension of MPC we compared it with MPC and with the excellent performing wavelet based scheme called SPIHT. Fifty chest radiographs were compressed and compared to originals in two ways. First, Peak Signal to Noise Ratio (PSNR) and five distortion factors from a perceptual distortion measure called PQS were used to demonstrate that our multi-resolution extension of MPC can achieve rate distortion performance that is 220% to 720% better than MPC and much closer to that of SPIHT. And second, in a study involving 724 radiologists' evaluations of compressed chest radiographs, we found that the impact of MR-MPC and SPIHT at 25:1, 50:1, 75:1 on subjective image quality scores was less than the difference of opinion between four radiologists.

abstract: Thesis

abstract: Master of Science (MS)


title: Process-Structure-Property Relationships in Selective Laser Melting of Aerospace Alloys

contributor:
Elbestawi, M. A.
Veldhuis, Stephen
Mechanical Engineering

subject:
Selective Laser Melting
Additive Manufacturing
Aerospace Industry
Solidification
Advanced Manufacturing
Ti-6Al-4V
Invar 36
Stainless Steel 316L

abstract: Metal additive manufacturing can be used for producing complex and functional components in the aerospace industry. This thesis deals with the process-structure-property relationships in selective laser melting of three aerospace alloys: Invar 36, stainless steel 316L, and Ti-6Al-4V. These alloys are weldable but hard to machine, which make them good candidates for the selective laser melting process. Invar 36 has a very low coefficient of thermal expansion because of its nickel concentration of 36% and stainless steel 316L contains 16-18% chromium that gives the alloy a corrosion resistance property. Ti-6Al-4V offers high strength-to-weight ratio, high biocompatibility, and outstanding corrosion resistance. Any changes in the chemical composition of these materials could affect their performance during application. In this thesis, a full factorial design of experiments is formulated to study a wide range of laser process parameters. The bulk density, tensile mechanical properties, fractography, microstructure, material composition, material phases, coefficient of thermal expansion, magnetic dipole moments, and residual stresses of the parts produced are experimentally investigated. An optimum process window has been suggested for each material based on experimental work. The thermal cycle, residual stresses, and part distortions are examined using a thermo-mechanical finite element model. The model predicts the residual stress and part distortion after build plate removal. The thesis introduces two laser energy densities for each material: brittle-ductile transition energy density, ET, and critical laser energy density, EC. Below the brittle-ductile transition energy density, the parts exhibited void formation, low density, and brittle fracture. Above the critical energy density, the parts showed vaporization of some alloying elements that have low boiling temperatures. Additionally, real-time measurements were taken using a pyrometer and a high-speed camera during the selective laser melting process. The trends found in the numerical results agree with those found experimentally.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Resistance Exercise For Enhancing Speed/Power Performance

title: The Role of High Resistance Exercise in Enhancing Speed/Power Performance

contributor:
Sale, Digby
Human Biodynamics

subject: high resistance exercise, exercise, speed, power, performance

abstract:
Ten subjects were randomly assigned to train one arm with ballistic movements (BT), whereas the other arm trained with ballistic and heavy resistance movements (BT+HRT). The training program consisted of three training sessions per week, over a ten week period. The BT arm executed ten sets of six maximal ballistic elbow extension actions (10% MVC), whereas the BT+HRT arm executed five sets of six repetitions of maximal ballistic actions followed by five sets of five to eight repetitions of heavy resistance elbow extension actions. After training, evoked twitch contractile properties, ballistic, 1 RM, and isometric MVC measures were analyzed. Incorporated with all performance measures were EMG recordings of the agonist (AG) triceps and antagonist (ANT) biceps. Muscle biopsies of triceps were also taken to determine muscle fibre type composition, and fibre area.
The BT+HRT arm demonstrated a significant decrease in the percent population of type IIb fibres (22% to 18. 8%). Furthermore, the BT+HRT arm produced hypertrophy, type IIa (6184 to 7086 μm²) and IIb (5714 to 6734 μm²) fibre areas increased, whereas type I fibre areas (3503 to 3828 μm²) did not significantly increase, after training. In contrast, the BT arm and control arm did not display fibre transformation or hypertrophy after training. Triceps evoked twitch peak torque increased for only the BT+HRT arm (12.5 to 13.8 N·m).
Furthermore, the 1 RM increased significantly in the BT+HRT arm (~24%) but did not change significantly in the BT arm. However, ballistic and isometric MVC PT values increased
similarly in both the BT (19.6 to 23.5 N·m; 45.4 to 52.6 N·m) and the BT+HRT (19.6 to 23.6 N·m; 49.6 to 56.0 N·m) arms.
The EMG results corresponded to the performance results in that triceps AEMG in the 1 RM test tended to increased more after HRT (0.71 to 1.01 mV) than only BT (0.72 to 0.81 mV),
but in the ballistic (HRT= 0.63 to 0.79 mV; BT= 0. 62 to 0. 73 mV) and isometric MVC performance measures (HRT= 0.80 to 0.84 mV; BT= 0.80 to 0.87 mV), the AEMG results were similar.
Supplementary HRT caused muscle hypertrophy, particularly of the type II fibres, but did not promote improvement in ballistic performance with loads equal to or less than 10% of
maximal isometric force.

abstract: Thesis

abstract: Master of Science (MS)


title: Latent Class Analysis of Diagnostic Tests: The Effect of Dependent Misclassification Errors

title: Latent Class Analysis: Dependent Misclassification Errors

contributor:
Walter, Stephen D.
Mathematics and Statistics

subject: diagnostic, tests, misclassification errors, dependent, latent class analysis

abstract: Latent class modelling is one method used in the evaluation of diagnostic tests when there is no gold standard test that is perfectly accurate. The technique demonstrates maximum likelihood estimates of the prevalence of a disease or a condition and the error rates of diagnostic tests or observers. This study reports the effect of departures from the latent class model assumption of independent misclassifications between observers or tests conditional on the true state of the individual being tested. It is found that estimates become biased in the presence of dependence. Most commonly the prevalence of the disease is overestimated when the true prevalence is at less than 50% and the error rates of dependent observers are underestimated. If there are also independent observers in the group, their error rates are overestimated. The most dangerous scenario in which to use latent class methods int he evaluation of tests is when the true prevalence is low and the false positive rate is high. This is common to many screening situations.

abstract: Thesis

abstract: Master of Science (MS)


title: Differences in the Experience of the 1918-1919 Influenza Pandemic at Norway House and Fisher River, Manitoba

contributor:
Herring, H.A.
Anthropology

subject:
1918-1919
influenza
Norway house
fisher river
Manitoba

abstract: This thesis discusses the impact of the 1918 influenza pandemic at Norway House and Fisher River, Manitoba. Despite sharing similar overall mortality rates during the pandemic, the two communities showed substantial differences when the distribution of deaths are examined at the family level. Reconstituted family data show that deaths were more tightly clustered within a small number of families at Norway House, while at Fisher River they were distributed amongst more families. Adults perished more often at Norway House than Fisher River. Historical documentation suggests, moreover, that the day-to-day functioning of Norway House was more severely disrupted than was the case for Fisher River. I argue that the differences in the family distribution of mortality at the two communities is linked to differences in social organization and, specifically, to the presence or absence of the Hudson's Bay Company. To test this hypotheses the data are examined using aggregate techniques, reconstituted family data and a technique outlined in Scott and Duncan's 2001 work.

abstract: Thesis

abstract: Master of Arts (MA)


title: Evaluation of the "Nickel-Ion Hypothesis" of Cytotoxic Responses in AS52 CHO Cells

title: The Nickel-Ion Hypothesis of Cytotoxic Responses

contributor:
Nieboer, E.
Biochemistry

subject:
nickel-ion hypothesis
cytotoxic responses
AS52 CHO cells

abstract: Eleven nickel compounds representing a range of solubilities and biological activities were tested for toxicity, mutagenicity, and cytosolic and nuclear nickel uptake in AS52 cells. values ranging LC50 from 2-130 ug Ni/ml for particulates and 120-150 ug Ni/ml for the water soluble salts (NiCl2, NiS04, Ni(CH3C00)2) were determined. The Ni(OH)2, NiC03 , and nickel sulphides (Ni3S2 , Ni 7S6 , amorphous NiS) exhibited similar toxicities (LC50's of 2.0, 5.8, 4.1, 8.2, 4.1 ~g Ni/ml respectively), while the nickel oxides were less toxic and showed large variations between the black, Li 2Ni 8010 , and green NiO forms (LC50's of 18.1, 75, 130 ug Ni/ml). Concentrations reducing survival to the range 20-80% were tested for mutagenicity and degree of nickel uptake. Although nickel compounds have been reported to be only weak or equivocal mutagens, the results indicate a low but significant increase in mutation rate at the gpt locus induced by all the nickel compounds tested. The majority of compounds displayed nuclear to cytoplasmic nickel ratios of ≈ 1:4 to 1:2, though this was ≈ 1:20 for nickel salts. NiC03 appeared to be intermediate in behaviour with a ratio of ≈ 1:12. Comparison of the eleven compounds at the same toxicity level (LC50) showed a 75-fold difference in exposure levels but about a 10-fold difference in cytoplasmic and nuclear nickel levels. There appears to be a very good correspondence between previously reported dissolution half times (T50's) of the compounds tested and the cytosolic nickel levels at a given toxicity level. For the water-soluble salts, previous reports have shown that cellular distribution varies from that of particulates due to differences in the manner of uptake. The present work confirms this and suggests that the compounds can be divided into three classes: watersoluble salts producing very low nuclear levels and high cytosolic levels, inert nickel oxides (green NiO and lithium nickel oxide) with relatively low nuclear and cytosolic nickel levels, and the remaining compounds (the major class) with relatively high cytosolic levels and nuclear nickel levels. Overall , the data supports the N i eke 1-Ion Hypothesis which suggests that the Ni 2+ ion is the active agent in nickel toxicity and mutagenicity, and that, as a first approximation, its intracellular concentration is responsible for the observed effects, irrespective of the nickel compound.

abstract: Thesis

abstract: Master of Science (MS)


title: The Influence of a Tentative Diagnosis on the Identification of Features from Patient Appearance

contributor:
Lee R., Brooks
Psychology

subject:
tentative diagnosis
patient appearance
identification features

abstract: The clinical signs that a physician can identify from the appearance of a patient represent an important source of information, upon which the diagnostic decision is nominally based. Most of the research in medical education emphasizes the organization of medical knowledge or the reasoning processes based on these signs. This emphasis carries the implicit assumptions that identifying features is not the major problem and that evaluation of the clinical signs occurs largely independently of consideration of the diagnosis. However, there is accumulating evidence to suggest that the identification of these clinical signs can be influenced by the diagnosis being evaluated. The studies in this thesis contribute to this body of research by investigating the underlying processes by which the diagnosis being considered influences feature identification. Participants in these experiments were asked to identify the clinical signs from photographs of patients or electrocardiogram strips after having been biased towards the correct or an alternate diagnosis. It was found that the availability of a diagnosis served both to change the probability of reporting relevant clinical signs as well as to influence the identification of ambiguous signs. Manipulating the credibility of the suggested diagnosis, subsequently suggesting a second diagnosis, or decreasing the size of the pool of alternatives available to the diagnostician had a large impact on diagnostic conclusions, but produced relatively small effects on the features reported. These results suggest that changing the degree of focus that a clinician places on the suggested diagnosis has a small effect on the identification of the features by comparison to the substantial effect of merely suggesting a diagnosis. Furthermore, it was found that the subsequent suggestion of a competing diagnosis did not lead to a reinterpretation of the data. This indicates that once clinicians have seen the evidence one way, they are unlikely to see and label it differently. The implication of these findings for research on medical decision making, the mental organization of medical categories, as well as medical education are discussed.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: The Social Geographies of Adult Immigrants with Disabilities in Canada

contributor:
Wilton, Robert
Newbold, Bruce
Geography

subject:
Disability
Immigrants
Canada
South Asia
Middle East
Social geography

abstract: Limited research has been done on adult immigrants with disabilities in Canada. Adopting a mixed-methodology, the thesis explores the intersection of immigrant status and disability from both a quantitative and qualitative perspective. Previous research on immigrants with disabilities has primarily focused on parents with disabled children. Little is therefore known about the lived experiences of adult immigrant with disabilities and how these experiences are negotiated and can change across time and place. The quantitative section of the thesis utilized the Participation and Activity Limitation Survey (PALS) from 2006 to examine the receipt of and need for services based on gender, immigrant status, income, education, and age. Quantitative results identified that immigrant women as receiving the least amount of services compared to any group, potentially resulting in them being more vulnerable compared to any other group. The qualitative part of the research consisted of two studies. First, community leaders and disability activists from Middle Eastern and South Asian communities were interviewed to examine the understandings of disability within their communities. Building on key informant findings, the second part explored the lived experiences of physically disabled adult immigrants from the Middle East and South Asia through in-depth interviews. Drawing on both quantitative and qualitative results it was identified that place, gender, culture, and policy significantly influence the lived experiences of immigrants with disabilities. Overall, the research highlighted the need for further research on larger service organizations and their provision of services to immigrants. The findings also identified the need for a greater understanding and provision of culturally appropriate services.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Limited research has been done on adult immigrants with disabilities in Canada. Adopting a mixed-methodology, the thesis explores the intersection of immigrant status and disability from both a quantitative and qualitative perspective. Quantitative methods examine and compare the receipt and need of support services between immigrants and the Canadian born population with disabilities. Building on the quantitative findings, the qualitative research adopts a feminist disability theory and an intersectional framework to explore the lived experience of immigrants with physical disabilities from the Middle East and South Asia, living in Canada. The qualitative chapter examines how different categories, for example disability, gender culture, religion, and immigrant status can intersect to create unique lived experiences that changes over time and place. The quantitative and qualitative findings were evaluated to further the knowledge of immigrants with disabilities and future research directions are suggested.


title: EXPERIENCES OF SOCIAL EXCLUSION AMONG OLDER WOMEN IN A RURAL CANADIAN CONTEXT

title: SOCIAL EXCLUSION AMONG OLDER WOMEN IN RURAL CANADA

contributor:
GOMBAY, CHRISTY
Global Health

subject:
SOCIAL EXCLUSION
OLDER
SENIORS
WOMEN
SOCIAL INCLUSION
ELDER

abstract:
Background: There is a burgeoning population of older adults globally and there is an increasing urgency in the policy literature to understand the health issues facing this population.  A social exclusion lens provides an opportunity to understand health inequity and disadvantage among vulnerable populations. There is limited research examining how social exclusion plays out for older women, particularly in the rural context. This study examines the social exclusion experiences of Canadian, rural, older women and highlights policy implications for global health practitioners.
Methods: Guided by the principles of interpretive description, this qualitative study included eight participants who identified as women, 65 years or older, spoke English, and who lived alone in private households in rural communities of Durham Region, Ontario. Concurrent data collection and analysis was conducted using an inductive approach.  One-to-one, semi-structured interviews were completed.
Findings: Six themes illuminate the exclusion experiences of rural, older women and they include: “Expectations of ageing in rural communities”; “Navigating the tensions of belonging within the social fabric”; “Singlehood isolation”; “Driving independence”; “Health infrastructure and changing personal health”; “Affording ageing”.
Implications & Contributions: The study adds a Canadian, rural perspective to the global conceptual literature on social exclusion. It illuminates the unique ways in which female gender and rural context influence social exclusion experiences.  Implications for global health policy include: recognizing health as a key category of exclusion and the need to address health equity, adopt a gender-specific and life-course approach to address social exclusion, foster a sense of belonging and peer connection, utilize unconventional channels for engagement, implement social support schemes and health programming which considers non-traditional families or single status as norm for family composition, and support affordable access to health-promoting programs and services.

abstract: Thesis

abstract: Master of Science (MSc)

abstract:
This study examines how older (senior) women, living in rural communities in Durham Region, Ontario experience social exclusion, and aims to help inform global health policies for older adults. Social exclusion is a way of understanding how processes interact to impact on someone’s ability to participate fully in their life
Six themes were identified and add to the global evidence on social exclusion. This Canadian study shows the unique ways in which female gender and the rural context influence on social exclusion experiences. Global health policy implications include: health is a key category of exclusion and addressing health equity is important, adopt a gender-specific approach that considers what happens over a lifetime that contributes to women’s exclusion, foster a sense of belonging and peer connection, use unconventional channels of engagement, and  implement social support schemes and health programming which considers non-traditional families or single status as norm for family composition.


title: A Study on the Effectiveness of the Flipped Classroom and Barriers to its Implementation in Mathematics

contributor:
Lovric, Miroslav
Mathematics and Statistics

abstract:
The flipped classroom is a restructuring of the learning process so that the gathering of information occurs prior to class and class time is used for problem-solving, discussion and synthesis – it is an inversion of the typical classroom structure. It is an approach to teaching and learning which has been gaining popularity, and has been implemented in courses across all disciplines and programs. However, this approach is not routinely used in the Mathematics and Statistics Department at McMaster University.

	How effective is the flipped classroom when used in mathematics? What are the challenges that instructors face when implementing this approach? This study will look at how effective the flipped classroom approach is in facilitating teaching and learning in a first year mathematics course, Math 1C03: “Introduction to Mathematical Reasoning”. We surveyed students about their experience with the flipped classroom to learn about their thoughts and perceptions. Then, we conducted interviews with faculty members within the department to better understand the barriers that prevent instructors from implementing the flipped classroom approach as well as comparing and contrasting the views of instructors with those of the Math 1C03 students.

abstract: Thesis

abstract: Master of Science (MSc)


title: Velocity Specificity in Resistance Training is Determined by Intended Rather than the Actual Contraction Velocity

contributor:
Sale, D. G.
Human Biodynamics

subject:
velocity
resistance training
contraction velocity

abstract:
Eight men and 8 women trained 3 days/ week for 16 weeks by doing attempted ballistic unilateral ankle dorsiflexions
against resistance which either rendered the resultant contraction isometric (one limb) or allowed a relatively high velocity (joint angular velocity of 5.23 rad.s- 1 ) isokinetic concentric contraction (other limb). Training sessions consisted of 5 sets of 10 contractions of each type. Pre and post-training tests of peak torque at 0, 0.26, 0.52, 1.04, 1.55, 3.02, 4.19, 5.23 rad.s-1 indicated a velocity specific training response (p<0.01), with increases of -5.9, 5.6, 8.6, 15.3, 13.9, 14.1, 19.3, and 27.4% respectively. In a separate test, maximal voluntary isometric peak torque (6 .1%) and maximum rates of torque development (20.4%) and relaxation (31.5%) increased after training (p<0.01). Electrically evoked isometric tetanic peak torque and rate of torque relaxation did not change but rate of torque development increased 12. 6% ( p<0. 01). Evoked peak twitch torque did not change but time to peak torque and 1/2 relaxation time decreased 6.2 and 11.9% respectively (p<0.01). Electromyographic (EMG) recordings of the agonist tibialis anterior (TA) during test contractions showed no change in integrated EMG, but there was an increase (14.6%, p<0.05) in antagonist soleus (S) EMG from mid-test to post-test. The velocity specific response to the isometric and isokinetic concentric training modes was the same, indicating that it was the
intent to make a ballistic contraction, rather than the resultant velocity of contraction, that determined the velocity specific response. The data also suggest that both neural and muscular adaptations contributed to the velocity specific training response

abstract: Thesis

abstract: Master of Science (MS)


title: Tri-ponderal Mass Index as a Measure of Adiposity in Survivors of Childhood Brain Tumors

contributor:
Samaan, M. Constantine
Medical Sciences

subject:
pediatric
cancer
obesity
brain tumors
survivors of childhood brain tumors
adiposity

abstract:
Introduction: Survivors of childhood brain tumors (SCBT) are an emerging group of cancer survivors that has an increased risk of cardiovascular disease, stroke, and type 2 diabetes. SCBT have equivalent obesity rates but excess fat mass (adiposity) when compared to the general population. As adiposity is an important and potentially modifiable risk factor for cardiometabolic outcomes in the general population, its measurement may allow for early stratification of adverse health outcomes in SCBT so that they can be targeted with prevention and treatment strategies designed to improve outcomes.
However, measuring adiposity often requires specialized equipment that is not always readily available, and a clinical measure is needed to facilitate these measurements in a feasible fashion. Tri-ponderal Mass Index (TMI; kg/m3) is a superior measure of adiposity compared to Body Mass Index (BMI) z-score in healthy children. However, it has not been assessed in SCBT. The aim of this thesis was to validate TMI as an adiposity measure in SCBT compared to non-cancer controls.
Methods: A cross-sectional analysis was completed from a cohort study sample including 44 SCBT (n=20 female) and 137 (n=64 female) healthy controls between 5-17 years of age. Total adiposity was determined by fat mass percentage (%FM) using bioelectrical impedance analysis and central adiposity was assessed by waist-to-hip (WHR) and waist-to-height (WHtR) ratios.
Results: TMI demonstrated equally strong correlations with total adiposity and stronger association with WHtR compared to BMI z-score in SCBT and healthy control children.
Conclusions: TMI may serve as a reliable and feasible clinical measure of adiposity in both SCBT and healthy children. The availability of TMI may allow for early stratification of survivors at risk of excess adiposity to allow early targeting with interventions to improve health outcomes.

abstract: Thesis

abstract: Master of Science in Medical Sciences (MSMS)

abstract:
Over the last thirty years, childhood cancer survival rates have greatly improved. However, these rates decrease over the lifespan of survivors. Certain groups within the survivors of childhood cancer population, including survivors of childhood brain tumors (SCBT), are at a higher risk of obesity, heart disease and type 2 diabetes. Excess body fat is a major contributor to the development of these adverse health outcomes in the general population and may represent an entry point to prevent and treat these conditions in SCBT. However, measuring fat mass in the clinical setting requires specialized equipment that can be expensive, time-consuming and not readily available in all settings. Therefore, this thesis aims to explore measures of fat mass that are both feasible and reliable in a clinical setting in SCBT compared to the general pediatric population.
We have identified the tri-ponderal mass index (TMI), defined as weight divided by height cubed (kg/m3) as a valid measure of the fat mass in both SCBT and healthy children. We conclude that TMI may serve as a reliable and feasible measure of adiposity in both SCBT and healthy children in clinical settings and assist in the early identification of survivors at risk of obesity and cardiometabolic outcomes to prioritize early interventions to improve outcomes.


title: Investigation of the effect of tool geometry on the machining process

contributor:
Veldhuis, Stephen
Mechanical Engineering

subject:
Tool edge geometry
Uncoated carbide
AISI 4140
FEA

abstract:
Cutting tool geometries play important roles in tool performance, such as tool life, surface
integrity, and cutting force. The most common commercial tools edge geometries are honed,
chamfered and hone-chamfered. This study investigates new ways to develop tool geometry.
An uncoated carbide tool is used in the orthogonal cutting of AISI 4140. By observing the tool
geometry changes in the machining process with white light interferometry, a new tool wear
geometry model has been proposed. A non-destructive tool wear measurement is discussed
as well. In addition, this study presents the machining result comparison between the new
and conventional geometries as well as the failure analysis from both experimental and FEA
perspectives.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Inference of Constitutive Relations and Uncertainty  Quantification in Electrochemistry

contributor:
Protas, Bartosz
Computational Engineering and Science

subject:
Electrochemistry
Inverse Modelling
Uncertainty Quantification
Bayesian uncertainty

abstract: This study has two parts. In the first part we develop a computational approach to the solution of an inverse modelling problem concerning the material properties of electrolytes used in Lithium-ion batteries. The dependence of the diffusion coefficient and the transference number on the concentration of Lithium ions is reconstructed based on the concentration data obtained from an in-situ NMR imaging experiment. This experiment is modelled by a system of 1D time-dependent Partial Differential Equations (PDE) describing the evolution of the concentration of Lithium ions with prescribed initial concentration and fluxes at the boundary. The material properties that appear in this model are reconstructed by solving a variational optimization problem in which the least-square error between the experimental and simulated concentration values is minimized. The uncertainty of the reconstruction is characterized by assuming that the material properties are random variables and their probability distribution estimated using a novel combination of Monte-Carlo approach and Bayesian statistics. In the second part of this study, we carefully analyze a number of secondary effects such as ion pairing and dendrite growth that may influence the estimation of the material properties and develop mathematical models to include these effects. We then use reconstructions of material properties based on inverse modelling along with their uncertainty estimates as a framework to validate or invalidate the models. The significance of certain secondary effects is assessed based on the influence they have on the reconstructed material properties.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Inference of Constitutive Relations and Uncertainty Quantification in Electrochemistry

subject:
Bayesian Uncertainty
Constitutive Relations
Inverse Modelling
Li-ion Battery
Diffusion Coefficient
Transference Number
Dendrite
Adjoint Analysis

abstract: This study has two parts. In the first part we develop a computational approach to the solution of an inverse modelling problem concerning the material properties of electrolytes used in Lithium-ion batteries. The dependence of the diffusion coefficient and the transference number on the concentration of Lithium ions is reconstructed based on the concentration data obtained from an in-situ NMR imaging experiment. This experiment is modelled by a system of 1D time-dependent Partial Differential Equations (PDE) describing the evolution of the concentration of Lithium ions with prescribed initial concentration and fluxes at the boundary. The material properties that appear in this model are reconstructed by solving a variational optimization problem in which the least-square error between the experimental and simulated concentration values is minimized. The uncertainty of the reconstruction is characterized by assuming that the material properties are random variables and their probability distribution estimated using a novel combination of Monte-Carlo approach and Bayesian statistics. In the second part of this study, we carefully analyze a number of secondary effects such as ion pairing and dendrite growth that may influence the estimation of the material properties and  develop mathematical models to include these effects. We then use reconstructions of material properties based on inverse modelling along with their uncertainty estimates as a framework to validate or invalidate the models. The significance of certain secondary effects is assessed based on the influence they have on the reconstructed material properties.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Development of Time-Resolved Diffuse Optical Systems Using SPAD Detectors and an Efficient Image Reconstruction Algorithm

contributor:
Deen, M. Jamal
Biomedical Engineering

subject: Time-Resolved Near-Infrared Spectroscopy

subject: Single-Photon Avalanche Diode (SPAD)

subject: Time-Correlated Single-Photon Counting

subject: Time-Resolved Diffuse Optical Tomography

subject: Complementary Metal-Oxide-Semiconductor (CMOS)

abstract:
Time-Resolved diffuse optics is a powerful and safe technique to quantify the optical properties (OP) for highly scattering media such as biological tissues. The OP values are correlated with the compositions of the measured objects, especially for the tissue chromophores such as hemoglobin. The OP are mainly the absorption and the reduced scattering coefficients that can be quantified for highly scattering media using Time-Resolved Diffuse Optical Spectroscopy (TR-DOS) systems. The OP can be retrieved using Time-Resolved Diffuse Optical Imaging (TR-DOI) systems to reconstruct the distribution of the OP in measured media. Therefore, TR-DOS and TR-DOI can be used for functional monitoring of brain and muscles, and to diagnose some diseases such as detection and localization for breast cancer and blood clot. In general, TR-DOI systems are non-invasive, reliable, and have a high temporal resolution.
TR-DOI systems have been known for their complexity, bulkiness, and costly equipment such as light sources (picosecond pulsed laser) and detectors (single photon counters). Also, TR-DOI systems acquire a large amount of data and suffer from the computational cost of the image reconstruction process. These limitations hinder the usage of TR-DOI for widespread potential applications such as clinical measurements.
The goals of this research project are to investigate approaches to eliminate two main limitations of TR-DOI systems. First, building TR-DOS systems using custom-designed free-running (FR) and time-gated (TG) SPAD detectors that are fabricated in low-cost standard CMOS technology instead of the costly photon counting and timing detectors. The FR-TR-DOS prototype has demonstrated comparable performance (for homogeneous objects measurements) with the reported TR-DOS prototypes that use commercial and expensive detectors. The TG-TR-DOS prototype has acquired raw data with a low level of noise and high dynamic range that enable this prototype to measure multilayered objects such as human heads. Second, building and evaluating TR-DOI prototype that uses a computationally efficient algorithm to reconstruct high quality 3D tomographic images by analyzing a small part of the acquired data.
This work indicates the possibility to exploit the recent advances in the technologies of silicon detectors, and computation to build low-cost, compact, portable TR-DOI systems. These systems can expand the applications of TR-DOI and TR-DOS into several fields such as oncology, and neurology.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


identifier: Feit, Harvey A. 1978. Waswanipi Realities and Adaptations: Resource Management and Cognitive Structure. Ph.D. Dissertation, McGill University, Department of Anthropology. 1683 pp. (Corrected copy.)

subject:
Ethno-ecology
Ecosystems Analysis
Cognitive Models
Ecological Anthropology
Nature-Culture
Hunting Knowledge and Recipies
Local Resource Management
Hunting Territories
James Bay Cree
Waswanipi Cree

abstract: The thesis copy in this Repository includes a page with notes of a few errors in labelling hunting territories, and corrections on the relevant pages. These errata are not on the thesis copy available at McGill University, at: http://digitool.library.mcgill.ca/thesisfile43592.pdf. The preparation of the thesis was done during two distinct blocks of time. When the James Bay Hydro-electric Project was announced in 1971 the Cree people from the region decided to fight the project in the courts, and then to negotiate a settlement with the Governments of Quebec and Canada. I was asked and to participate in their opposition, the court case and then in the negotiation and implementation of the James Bay and Northern Quebec Agreement that ensued. I welcomed the opportunity. It thus worked out that the information and knowledge recorded by the co-research done jointly with Waswanipi Cree people between 1968 and 1970, and reported in the initial drafts of the thesis in 1971-72, were applied and used before the full results of the research were in a form that was appropriate for university thesis submission. The thesis preparation and writing were completed part-time in 1977-78 during the continuing initial implementation of the JBNQA, and the thesis was defended in 1979. The thesis is very long and not as readable as it would have been with additional editing and cutting. The main information and findings of the thesis research are presented in a series of articles published both prior to and following thesis completion. Preliminary reports of the dissertation research were presented in: 1971, L'ethno écologie des Cris Waswanipis, http://hdl.handle.net/11375/23942; edited and reprinted in English in 1973 as, The Ethno-Ecology of the Waswanipi Cree, http://hdl.handle.net/11375/24143; 1972, The Waswanipi of James Bay, http://hdl.handle.net/11375/23561; 1973, The Twilight of the Cree Hunting Nation [editor’s title], http://hdl.handle.net/11375/23564; and, 1973, Expert Testimony in Superior Court, Québec, Case No. 05-04841-72, http://hdl.handle.net/11375/24034. Following completion of the dissertation reports of findings were presented in: 1988 [1987], Waswanipi Cree Management of Land and Wildlife, http://hdl.handle.net/11375/24145; the first sections of 2014 [1986], Hunting and the Quest for Power, http://hdl.handle.net/11375/23927; 1986, James Bay Cree Indian Management and Moral Considerations of Fur-bearers, http://hdl.handle.net/11375/23936; 1987, North American Native Hunting and Management of Moose Populations, http://hdl.handle.net/11375/23935; and later 1994 Dreaming of Animals, http://hdl.handle.net/11375/23915; and 2000, Les animaux comme partenaires de chasse, http://hdl.handle.net/11375/23535 (with an English version). Other publications have drawn on the dissertation, some extensively, but they include significant material from later research.

abstract: Each of the two main paradigms for ecological anthropology, ecosystems analysis and ethno-ecology, explores only one pair of phenomena relevant to cultural ecology, environment and action, or environment and cognition-belief respectively. This study argues that ecological analysis is weakened by the exclusion of any one of those three orders of phenomena as objects of study. A detailed analysis of cognitive models and behavioral practices of resource management of Waswanipi Cree hunters shows how cognitive knowledge and religious beliefs incorporate realistic environmental relationships and practical possibilities for action; and, how action informed by those models and beliefs can effectively manage hunting, animal populations, human social distributions on the land, and subsistence. Cognitive models and beliefs are formulated as recipes for action that can be used in diverse situations so that actions are responsive to changing environmental and social conditions. Decisions concerning alternative goals, situations and strategies are shown to be socially located with the men who are the "owners" of hunting territories and leaders for their use. - - L'anthropologie écologique traite de trois catégories de phénomènes: culture, environnement et comportement. Les deux "nouveaux" paradigmes explorent seulement deux des trois phénomènes relatifs a l'écologie culturelle, l'analyse des ecosystèmes qui traite de l 'environnement et du comportement et l'ethnoécologie qui traite de l'environnement et de la culture. La présente étude indique l'importance de l'interaction entre les trois catégories de phénomènes. Une analyse détaillée des données sur les croyances et le comportement concernant l'aménagement des ressources par les chasseurs cris Waswanipi démontre comment ces croyances religieuses reflètent à la fois la structure culturelle et les relations concrètes avec l'environnement; et comment le comportement de ces chasseurs en accord avec leurs croyances peut effectivement contrôler la chasse, les populations animales, la distribution géographique des populations humaines ainsi que leur subsistance. Les croyances se réalisent sous forme de recettes s'appliquant à des situations diverses et par la suite le comportement des chasseurs s'adapte aux conditions changeantes. Les décisions concernant les buts, les situations et les stratégies sont prises par les hommes qui sont reconnus socialement comme étant les "propriétaires" des territoires de chasse.

abstract: Canada Council Doctoral Scholarship, Canadian Museum of History research grants, McGill University Steinberg Summer Research Fellowships, McGill Northern Research Committee research grants, and Carleton University Department of Sociology and Anthropology publication preparation grants.


title: Deficits or Differences? A New Methodology for Studying Pragmatic Language in Autism Spectrum Disorder

contributor:
Stroińska, Magda
Cognitive Science of Language

subject:
Autism Spectrum Disorder
Pragmatics
Research Methods
Conversational Turn Taking
Non-Literal Language
Figurative Language
Pragmatic Impairments
Linguistic Analysis

abstract: This dissertation proposes a new method of studying pragmatic language use in autism spectrum disorder (ASD). The existing research into pragmatic language use in ASD has predominantly used interviews and experiments in clinical environments to gather data from participants with ASD. These research methods focus heavily on comprehension, on comparing the performance of the participant with ASD to their non-autistic interlocutor. The methodology proposed in this thesis involves using observation and a naturalistic environment to gather conversational data that can be used to fill several gaps in the current research on pragmatic language use in ASD. In this study, people with ASD interacted with either non-autistic people or other people with ASD in triadic conversation sessions. These sessions were recorded, transcribed, and analysed for various pragmatic uses of language that previous research had observed were impaired, such as types of non-literal language and conversational turn taking. The pragmatic language use of three participants with ASD, representing three different levels of language ability, was analysed. The results showed that some participants used types of pragmatic language differently based on with whom they were communicating and also that some purported pragmatic impairments in ASD may not be as ‘impaired’ as they seemed based on previous research. For example, while all participants in this study used more interruptions when interacting with others with ASD compared to when interacting with non- autistic people, the rates of interruption were far less than what has been observed between non-autistic speakers (Hancock & Rubin, 2014), even though people with ASD have been described in the research literature as interrupting frequently (Ochs, Kremer-Sadlik, Sirota, & Solomon, 2004). The research presented in this dissertation has implications for future clinical research into pragmatic language impairments in any speech community and provides an additional methodology that can be used, expanding on the types of research questions that can be investigated in this area.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: This thesis proposes a new method of studying pragmatic language use in people with autism spectrum disorder (ASD). This methodology involves using observation and the data that can be gathered using it can fill several gaps in the current research on pragmatic language use in ASD. In this study, people with ASD interacted with either non-autistic people or other people with ASD in triadic conversation sessions. These sessions were recorded, transcribed, and analysed for various aspects of pragmatic uses of language. The pragmatic language use of three participants with ASD, representing three different levels of language ability, was analysed. The results showed that some participants used types of pragmatic language differently based on with whom they were communicating and also that some purported pragmatic impairments in ASD may not be as ‘impaired’ as they seemed based on previous research.


title: Hybrid FPGA/MCU Supervisory Controller for Multi-Source Inverter Integrated with Hybrid Energy Storage System in Electrified Vehicles

contributor:
Emadi, Ali
Electrical and Computer Engineering

abstract:
This thesis discusses how to apply parts of the aerospace safety standard processes and guidelines such as the DO-254 and DO-160 to the firmware and hardware design of a supervisory control board for the E/E powertrain  systems of an electric vehicle. A supervisory control board is developed as an ECU that is a computer-based electronic module intended to be used for automotive and aerospace applications. The functions of the developed ECU acquires/monitors system parameters, isolates and detects system faults, and communicates with the vehicle. The ECU includes two main sub-modules including a safety critical digital core based on NXP's MPC5777m MCU and a FDAC system based on Xilinx's Artix-7 FPGA. ECU micro-processing module and digitized analog I/O processed in an FPGA for aerospace application will enable this technology for the automotive application for fast and reliable supervisory controls capable of handling complex multi-physics control strategies.

A Neural Network Energy Management Controller (NN-EMC) is also designed and applied to a HESS using the Multi-Source Inverter (MSI). Its aim is to manage the current sharing between a Li-ion battery and an Ultracapacitor by actively controlling the operating modes of the MSI. A discharge duty cycle that biases the use of one source over another is used as the control variable. To limit the battery wear and the input source power loss, an optimized solution is obtained with Dynamic Programming (DP). The NN-EMC is designed with an artificial neural network and trained with the optimized duty cycle obtained by DP. The DP/NN-EMC solution was compared to the battery-only Energy Storage System (ESS) and the HESS-MSI with 50\% discharge duty cycle. Both the battery RMS current and peak battery current have been found to be reduced by 50\% using the NN-EMC compared to the battery-only ESS for the New York City drive cycle.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: The Effect of Access Road Construction on the Hydrology of Wetlands in Rock Barren Landscapes

contributor:
Waddington, James Michael
Earth and Environmental Sciences

abstract: Dense networks of access roads can be found across the Canadian landscape. Though necessary for natural resource and mineral exploration projects, access roads are linear disturbances that can alter hydrological processes operating within the landscape. While this has previously been studied in many landscapes, research has not been conducted in wetland-dominated depressional landscapes of the Precambrian shield. As such, four wetlands were instrumented with paired monitoring wells and piezometer nests to assess hydrological change upstream and downstream of the road cut-through. In all four wetlands, the road obstructed the movement of lateral flow, resulting in ponding upstream as water was discharged to the surface. Downstream of the road, the wetland experienced a lowered water table due to reduced water inputs, especially during drought conditions. The difference between the upstream and downstream water table position (∆WT) was largest when the culvert was placed 20 cm above the surface, indicating that large water inputs and prolonged flooded conditions was required for water to be permitted downstream. Conversely, the ∆WT was smallest when the culvert was embedded 50% into the subsurface, confirming a previous suggestion (Phillips, 1997) that partial burial is the ideal culvert placement to maintain drainage patterns. In wetlands with comparable culvert placements (perched on the moss surface), the ∆WT was smallest in the wetland that received not only water input from lateral flow, but from groundwater discharge and overland flow as well. This suggests that multiple water sources are important to provide water to the bisected unit downstream of the road cut-through. Furthermore, wetlands with a groundwater connection and deeper depression depths were capable of maintaining a water table during drought conditions, and as such were not subjected to long-term aerobic conditions that can result in peat degradation. In general, the ∆WT was higher in the wetland during the fall rewetting than during the drought. Provided that culvert design was standardized throughout the road network, wetlands that received a greater contribution of overland flow would be at a greater risk for flooding and subsequently hydrological change. As such, a GIS model was created to assess the relative flooding potential of wetlands using criteria (catchment area, proportion of rock cover, stream order, surface water connection) that represents the first-order controls on runoff in Precambrian shield landscapes (T3 template; Buttle, 2006). The model output was evaluated using field data, where wetlands were ranked based on its water table position during the winter period when snowmelt was assumed to occur. The model was capable of assessing the hydroperiod of different wetland types, where the highest and lowest flooding potential was associated with marshes and bogs, respectively. A higher flooding potential was also associated with deeper depressions, which have been shown to have a higher hydroperiod (Didemus, 2016). The flooding potential of wetlands was variable throughout the landscape, and was not correlated with a particular wetland metric (i.e. wetland type, wetland area). The model results suggest that wetlands can be assessed based on flooding potential, in conjunction with other traditionally used wetland metrics. As such, an understanding of the hydrological function of wetlands, and proper selection of culvert design and wetlands for road crossing can be completed in order to minimize hydrological change associated with the construction of access roads.

abstract: Dissertation

abstract: Master of Science (MSc)


title: Computational Optimization of Structural and Thermal Compliance Using Gradient-Based Methods

contributor:
Protas, Bartosz
Kim, Ill Yong
Mathematics

subject: Topology Optimization, Gradients, Riesz Representation Theorem

abstract:
We consider the problem of structural optimization which has many important applications
in the engineering sciences. The goal is to find an optimal distribution of the
material within a certain volume that will minimize the mechanical and/or thermal
compliance of the structure. The physical system is governed by the standard models
of elasticity and heat transfer expressed in terms of boundary-value problems for elliptic
systems of partial differential equations (PDEs). The structural optimization problem
is then posed as a suitably constrained PDE optimization problem, which can be solved
numerically using a gradient approach. As a main contribution to the thesis, we derive
expressions for gradients (sensitivities) of different objective functionals. This is done
in both the continuous and discrete setting using the Riesz representation theorem and
adjoint analysis. The sensitivities derived in this way are then tested computationally
using simple minimization algorithms and some standard two-dimensional test problems.

abstract: Thesis

abstract: Master of Science (MSc)


title: Nanowire-Based Alternating Current Oxide Powder Electroluminescent Materials and Devices

contributor:
Kitai, Adrian H
Materials Science and Engineering

subject:
Electroluminescent
Nanowire
Heterogeneous junction
Electrical Field Enhancement
Simulation

abstract:
A novel type of alternating-current (AC) powder electroluminescent (EL) device that relies on nanowire-phosphor heterogeneous junction structure has been developed. It shows promise for manufacturing of highly stable powder EL devices. To pursue this goal, manganese ion (Mn2+)-doped zinc germanate (Zn2GeO4:Mn) oxide phosphor was synthesized and used as EL powder material for the fabrication of the new types of AC powder EL devices. The Zn2GeO4:Mn oxide phosphor powder could eliminate the well-known degradation problem of zinc sulfide (ZnS)-based AC powder EL devices predominant in the current marketplace.
     In order to realize a high brightness at a relatively low operating voltage, a conductive semiconductor nanowire architecture using zinc oxide (ZnO) and copper oxide (CuO) nanowires with sharp-tip features, was created and integrated into conventional AC powder EL structures. Particularly, vertically-aligned n-type ZnO nanowires arrays were successfully synthesized on a Zn2GeO4:Mn polycrystalline substrate for the first time, and the growth behavior using a chemical vapor deposition (CVD) process was investigated. The density of the ZnO nanowires could be effectively controlled by some experimental parameters, such as the density of gold catalyst nanoparticles, and spatial distance between substrate and CVD source powders. This novel ZnO nanowire-decorated Zn2GeO4:Mn phosphor architecture was used to fabricate top-emission AC powder EL devices. On the other hand, a vertically-aligned ZnO nanowire array was directly synthesized on a thin film indium-tin-oxide (ITO)-coated glass substrate for fabrication of bottom-emission AC powder EL device. The nanowires were adopted to form heterogeneous junction structures between the tips of the nanowires and the Zn2GeO4:Mn EL powders, so that the composites could have a similar electrical field enhancement as in the needle-like CuxS precipitates within widely-used ZnS:Cu EL powder materials. The behavior of these top- and bottom- emission AC powder EL devices was also studied.
      Alternatively, vertically-aligned p-type CuO nanowires were prepared by a thermal oxidation method. Reliable heterogeneous junction structures were formed by a simple drop-coating method. The CuO nanowire-based AC powder EL device has excellent brightness maintenance with a loss of luminescent intensity under 1 % at over 10 cd/m2 luminance during 360 hours of operation. The integrating of semiconductor nanowires into conventional AC powder EL device structures offers the very promising prospect of fabrication of simple, low-cost, scaled-up EL devices that could fundamentally solve the limited operational lifetime of current ZnS-based AC powder EL devices.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Application of edge preparation technologies to improve tool performance

subject:
Cutting edge geometry
Cutting edge preparation
Abrasive jet machinig
Tool performance

abstract:
In machining, tool life is the chief determinant of cost, tool changing frequency, machining efficiency, and machining precision. Application of a proper cutting edge with optimized geometry and suitable edge properties is an effective way to improve tool performance and machining quality.
The majority of the reported work is limited to the effect of edge geometry on tool life. In this thesis, cutting edges were prepared using three different methods which were evaluated in terms of tool edge geometry produced, tool surface quality and topographies, edge hardness and residual stresses. Furthermore, the influence of cutting edge preparation techniques on the tool performance of uncoated tungsten carbide cutting inserts with different average cutting edge rounding  (S¯),  different form factor (K), as well as the different edge preparation methods used underwent experimental investigation through the orthogonal turning of AISI 4140 alloy steel. Results show that the performance of the prepared edge depends on the combined effect of micro-geometry and edge properties. For symmetric edges (K=1), the preferable range for S¯ was found to be 20 µm to 30 µm.  Drag finishing was determined to be the best edge preparation process which is able to produce cutting edges with the best performance.
The experimental investigations provided guidelines and evidence for future study of the cutting tool life and wear behavior of prepared cutting inserts and PVD-coated carbide inserts.

abstract: Thesis

abstract: Master of Applied Science (MASc)