title: Comparison of Faculty Versus Structured Peer Feedback: Implications of Technical Skills Training

contributor:
Zevin, Boris
Education

subject:
Feedback
Evaluative Judgement
Assessment
Self-Regulated Learning
Technical Skills
Medical Education

abstract:
The surgical training environment has been required to adapt to multiple changes in recent years. Two challenges have placed significant burdens on traditional training methodology: the emerging need for critically reflective clinicians, and restrictions in the traditional methods of technical skills training. Implementing training for these disparate elements is challenging. Simulation-based training has been widely used to teach both technical and non-technical skills to medical students and residents, however consistent access to faculty feedback during training and implementation of critically reflective activities remains problematic. Self-regulated learning can be used to both provide the mechanism by which skill acquisition and critical reflection can occur. This research consisted of two complimentary studies examining technical skill acquisition and self-regulated learning in medical students using structured peer-feedback to learn technical skills.
The technical skills study consisted of two prospective randomized controlled trials comparing structured peer-feedback versus traditional faculty feedback for the acquisition of a technical skill. Participants in the peer-feedback group provided feedback to each other using a structural process taught through pre-training with an assessment tool. Participants completed five attempts at the skill over four days. Performance in the peer-feedback group was found to be non-inferior to the faculty group across all assessment criteria used in the study: blinded expert assessment, time to completion and functional test.
The impact on self-regulated learning was examined using thematic analysis of student responses to multiple surveys and the written feedback provided by the peer-feedback group. Students developed increasingly sophisticated assessment and feedback skills through regular small exposures to the assessment task. Evidence of self-regulated learning was demonstrated by students’ improvement in technical performance, evaluative judgement of their peer’s performance, self-identification of the benefit of these assessment skills to their own learning, and subsequent implementation of these skills in other contexts. Despite improved assessment skills students did not believe the feedback they provided was beneficial – likely due to a lack of external feedback on their assessment skills from faculty.
This research has demonstrated that with appropriate support, structured peer-feedback can be used to augment traditional faculty led training, whilst additionally developing students’ evaluative judgement and self-regulated learning.

abstract: M.Ed.


title: Fatigue-Independent Alterations in Muscle Activation and Effort Perception During Forearm Exercise: The Role of Local Oxygen Delivery

contributor:
Tschakovsky, Michael
Kinesiology and Health Studies

rights: Attribution-NonCommercial-NoDerivs 3.0 United States

rights: Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada

rights: ProQuest PhD and Master's Theses International Dissemination Agreement

rights: Intellectual Property Guidelines at Queen's University

rights: This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.

subject:
Oxygen Conforming Response
Local Oxygen Delivery
Muscle Activation
Perception of Effort
Voluntary Exercise

abstract: In exercise, the sensations of effort to make the muscles do exercise can contribute to an individual’s decision to stop exercise or decrease exercise intensity. Skeletal muscle fatigue is one mechanism by which the effort required to continue exercise can be increased. In order to continue exercise with fatigued skeletal muscle we must increase the amount of electrical signals sent to the muscle. This increase in electrical signals sent to the muscle is perceived by the exercising individual and is interpreted as increased perception of effort to maintain the same exercise intensity. Another mechanism which may also require increased electrical activity sent to the muscle and therefore may increase perception of effort for the same exercise intensity is exercise where oxygen delivery is suboptimal, resulting in reduced oxygen levels (oxygenation) in the muscle. When human and animal muscle is electrically stimulated, force produced for a given electrical stimulation decreases when muscle oxygenation is reduced. When muscle oxygenation is restored force produced is also rapidly restored for the same electrical stimulation. This rapid adjustment of force for the same electrical stimulation with changes in muscle oxygenation is referred to as the oxygen conforming response (OCR). However, the existence of an OCR in voluntary human exercise has not been established and it remains to be determined if our perceptions of effort will follow changes in electrical signal sent to the muscle as a result of the OCR. We tested these unanswered questions by intermittently reducing forearm blood flow (FBF) during human (n = 16) handgrip exercise. When FBF was reduced, electrical activity and perception of effort increased. Interestingly, upon the first restoration of FBF neither electrical activity nor perception of effort were restored. We interpreted these findings to be consistent with skeletal muscle fatigue development during the first compromise to muscle oxygenation. Upon the second restoration of FBF both electrical activity and perception of effort were restored, which is consistent with an OCR and its ability to rapidly modify perception of effort in voluntary human exercise. Through its effects on effort perception, the OCR may therefore have important implications for exercise behaviour.

abstract: M.Sc.


title: Investigation of the presence and impact of environmentally-adapted Escherichia coli in private well water in southeastern Ontario

contributor:
Majury, Anna
Brown, Stephen
Environmental Studies

subject:
Environmentally-Adapted E. coli
Private Well Water
Water Quality
Cryptic Clades
Fecal Indicator Bacteria
Escherichia coli

abstract:
The fecal contamination of drinking water causing acute gastrointestinal illness remains a threat to public health in Canada, including Ontario, particularly in rural regions reliant on private well water. To determine potability, water is assessed for the presence of fecal indicator bacteria (FIB) to indicate contamination with harmful fecal pathogens. Escherichia coli remains the most frequently employed FIB, given it is a natural inhabitant of the gastrointestinal tract (GIT) of warm-blooded animals. However, the use of E. coli as a FIB has been questioned in recent years with the identification of populations of environmentally-adapted E. coli capable of survival and growth outside of the GIT, including in water and soil. Environmentally-adapted E. coli do not represent a recent fecal contamination event and thus challenge the current dogma that the presence of E. coli in water always reflects recent contamination from a fecal source and the potential presence of fecal pathogens.

This study hypothesizes that environmentally-adapted E. coli populations are present in private well water in southeastern Ontario. Environmentally-adapted populations were characterized by comparing the genetic signature and phylogenetic origin of E. coli isolates obtained directly from feces of a variety of hosts to that obtained from domestic private well water samples, both collected from southeastern Ontario. Quantitative polymerase chain reaction and accessory gene fingerprinting were employed to facilitate identifying genetic fingerprints unique to well water and, in combination with phylogroup analysis, this revealed the presence of environmentally-adapted E. coli populations in 66% of the 76 E. coli positive wells analyzed. All isolates sampled from 37% of E. coli positive wells were exclusively of environmentally-adapted populations. These findings show that environmentally-adapted E. coli are widespread in domestic private well water in southeastern Ontario. This is the first study to investigate and report the presence of environmentally-adapted E. coli in private well water. As a result, the reassessment of E. coli as the principle FIB is required, as well as a review of current water quality testing methodology and interpretation. These findings may inform future drinking water quality guidelines, policy, and public health risk assessment.

abstract: M.E.S.


title: A Multi-Site Evaluation of Contact-Based Anti-Stigma Programs For High School Youth

contributor:
Stuart, Heather
Public Health Sciences

subject:
Social Stigma
Mental Illness
Social Distance
Stereotyping
Prejudice
Adolescents
Contact-Based Education
Evaluation
Validation
Scale

abstract:
Adolescents have become an important target for contact based anti-stigma programs. Research on mental health stigma reduction in adolescents has been hindered by lack of validated measures to evaluate interventions. To reduce stigma and improve mental health, we need the capacity to observe and measure stigma and to evaluate whether or not interventions are producing the desired effect. The many scales used to measure attitudes towards people with mental illness that exist today are not adequate as they have been developed for the adult population outside of the intervention setting.

The first objective was to develop two scales, one to measure stereotypic attributions toward people with a mental illness and another to measure social acceptance of those with a mental illness. The second objective was to use the scales to evaluate three different types of contact-based interventions that were delivered by one program.

Survey data were collected from adolescent students aged between 12 and 19 years Qualitative methods, including expert opinion and focus group discussion were used for item generation, item review and refinement, and in general to establish content validity. Quantitative methods, such as exploratory and confirmatory factor analysis, known group differences, Cronbach’s alpha and test-retest reliability were also used to assess validity and reliability. For the second objective students received one of three contact-based interventions or a comparison situation. Data were analyzed using linear regression.

Results showed that a one-factor solution was the best fit for the data for each scale.  When programs were evaluated, larger improvements were seen on the Stereotypic Attributions scale than on the Social Acceptance scale. For the second objective all three interventions types showed a positive change in social acceptance compared to a group that did not receive an intervention.

This study has established initial reliability and validity of two scales to evaluate youth attitudes towards and social acceptance of those with a mental illness in a wide range of samples of students from middle and high schools in Canada.  This study has also demonstrated that contact-based education provided in class, as an assembly, or as a student summit can be promising practices for reducing stigma in middle and high school students.

abstract: PhD


title: Impact of various stimulus properties on fusional vergence range and heterophoria

contributor:
Troje, Niko
Psychology

subject:
Psychology
Vision
Binocular Fusion
Vergence
Heterophoria

abstract: Binocular fusion is our ability to combine the two separate retinal images into a single fused image, even if the images are separated by a certain amount of disparity. We hypothesized that lower spatial frequencies sampled over a large field of view (FOV) contribute to extending the fusional vergence range (FVR), which is the extent to which binocular single vision (BSV) can be held together with increasing image disparities. Testing these properties allows for the illustration of the contribution of the monocular periphery to binocular fusion. Two separate experiments were run to test this hypothesis; one which varied the spatial frequency of stimuli and one which varied the FOV. Both experiments involved the use of a head-mounted display (HMD) to haploscopically present stimuli to participants. The procedure involved participants manually moving the stimuli apart from each other until they perceptually separated and then back together until they fused, with the resulting disparity at these points being used to calculate the FVR, along with the hysteresis and any potential heterophoria present. The first experiment found the opposite effect of spatial frequency than what was reported in the literature, with lower spatial frequencies resulting in a lower FVR. The second experiment did not find any effect of FOV. These differences compared to the literature could be the result of using an HMD methodology, or the use of complex images as stimuli (which was found to result in a larger FVR than the literature). In future research, the use of different methodologies with complex images would provide a useful comparison to the current results obtained with an HMD, as well as a test of the interactions between spatial frequency and FOV.

abstract: M.Sc.


title: Impact of Vascular Calcification on the Regulation of Circulating Minerals and Hormones in Experimental Chronic Kidney Disease

contributor:
Adams, Michael
Holden, Rachel
Biomedical and Molecular Sciences

subject:
Phosphate
Chronic Kidney Disease
Vitamin D
Calcium
Parathyroid Hormone
Fibroblast Growth Factor-23
Vascular Calcification
Calcitriol
Circadian variation
Diurnal variation

abstract:
Cardiovascular disease (CVD) is a significant concern in chronic kidney disease (CKD) accounting for over half of all mortality. The high CVD prevalence in CKD is not accounted for by traditional Framingham risk factors (e.g. smoking, obesity) and is likely influenced by CKD-mineral bone disorder (CKD-MBD). CKD-MBD consists of abnormalities in circulating calcium, phosphate, vitamin D, and parathyroid hormone (PTH), as well the development of soft tissue calcifications like vascular calcification (VC). CKD-MBD has been well-characterized clinically and experimentally, however, significant knowledge gaps exist pertaining to: treatment targets and modalities, daily variation in minerals/hormones, the impact of the circulating factors versus local factors on VC, and inversely the impact of VC on the circulating mineral/hormonal milieu.
A dietary adenine model was used to induce CKD in rats with differing phosphate diets to propagate/mitigate CKD-MBD. In comparison to healthy rats those with CKD displayed a shift for the acute accrual of infused phosphate and calcium into vascular beds instead of the kidneys and bone. VC amplified this preferential vascular accrual. Further, a preceding phosphate pulse amplifies vascular calcium accrual.
In experimental CKD rats CKD treated with calcitriol, alteration of neither the bolus dose nor daily dose administered resulted in improvements to any CKD-MBD parameters. Additionally, adhering to guideline-recommended PTH suppression targets did not provide any benefits in CKD-MBD, other than reducing circulating PTH.
In CKD rats fed different phosphate diets, it was found that low phosphate mitigated the pathologic increases in circulating minerals/hormones and protects against VC. Fibroblast growth factor-23 was identified as a potential biomarker for VC in CKD as it was significantly elevated in CKD rats with VC, and early elevations during CKD-induction predicted eventual VC.
The daily variations in circulating minerals/hormones was characterized in experimental CKD. It was found that kidney dysfunction did not independently impact circulating minerals/hormones, but that VC significantly impacted the daily variation in circulating phosphate.
These findings identify critical areas that need further investigation pertaining to CKD-MBD treatment, as well as expand current knowledge of how the circulating CKD milieu impacts the development of VC and in turn how VC impacts the circulating milieu.

abstract: PhD


title: Investigating the role of von Willebrand factor (VWF) in angiogenesis

contributor:
James, Paula
Pathology and Molecular Medicine

subject:
BOEC
angiogenesis
aortic stenosis
von willebrand disease
von willedrand factor

abstract:
Gastrointestinal bleeding from angiodysplasia can be a debilitating problem for patients with defective or deficient von Willebrand factor (VWF). Studies have pointed to a regulatory role for VWF in vessel formation however, the mechanisms are not completely understood. We used endothelial cell models and VWF-deficient mice to explore how VWF and in particular VWF multimers regulate angiogenesis. Our main findings are that blood outgrowth endothelial cells (BOECs) from patients with inherited and acquired VWF abnormalities display aberrant angiogenesis, circulating VWF multimers negatively regulate cell proliferation, both intracellular and extracellular VWF are likely needed to modulate angiogenesis, and VWF-deficient mice have increased vessel formation.

We found abnormal angiogenesis in BOECs from patients with von Willebrand disease (VWD) and aortic stenosis (AS). VWD BOECs had abnormal storage and secretion of VWF associated with increased secretion of the pro-angiogenic molecule angiopoietin-2 (Ang-2), impaired cell migration, and increased proliferation of some patient cells. AS patients presented with VWF plasma defects including a loss of high molecular weight multimers (HMWM) prior to surgery relative to after, suggesting increased proteolysis pre-operatively in a shear-dependent manner. Correspondingly, BOECs isolated from AS patients before surgery were more proliferative than controls and had increased intracellular Ang-2.

A role for VWF HMWM in modulating cell proliferation is supported by the increased proliferation of BOECs from type 2A VWD and AS patients. Additionally, VWF-deficient cells cultured in the absence of circulating multimers were more proliferative than cells cultured in the presence of even 50% VWF multimers. However, regardless of the circulating VWF multimer content, in the absence of intracellular VWF, cell migration velocity and tubule formation remained unchanged. These observations indicate that both intracellular and extracellular VWF may be required to comprehensively influence angiogenesis.

Lastly, we confirmed that VWF has a negative regulatory role in angiogenesis in a mouse model. This was evidenced by the fact that Matrigel plugs from VWF-deficient mice and the ears of one-month old VWF-deficient mice were more vascularized than wild-type.

Collectively, these studies point to a multifaceted role for VWF in angiogenesis and expand our existing knowledge on the mechanisms by which VWF regulates vessel formation.

abstract: PhD


title: Colorectal cancer diagnostic pathways in Ontario

contributor:
Groome, Patti
Flemming, Jennifer
Public Health Sciences

subject:
Colorectal cancer
Diagnostic pathways
Diagnostic interval

abstract:
Purpose: The purpose of this study was to differentiate diagnostic pathways in colorectal cancer in Ontario through the development of a pathway categorization scheme, and evaluate the patient-, disease-, system-related characteristics of patients and the length of the diagnostic interval across the diagnostic pathway categories.
Methods: This was a cross-sectional study using an existing cohort at ICES. The study population included patients who were diagnosed with colorectal cancer in Ontario between 2009 and 2012. Cluster analysis used eleven variables that were related to patient presentation, patient visit pattern, patient symptom pattern and referral process to characterize and categorize diagnostic pathways. Chi-square test and One-way ANOVA were used to assess the association between the examined factors (age, sex, material deprivation quintile, comorbidities, and stage) and the diagnostic pathway categorization scheme. Unadjusted quantile regression was used to assess the association between the diagnostic interval length and the diagnostic pathway categorization scheme.
Results: Six distinct diagnostic pathways were identified: asymptomatic pathway (N=4,494), colonoscopy pathway (N=10,066), the imaging and colonoscopy pathway (N=3,427), imaging alone pathway (N=2,238), the imaging and emergency presentation pathway (N=2,849) and no pre-diagnostic workup pathway (N=887). Patients who went through a pathway that was more adherent to diagnostic pathway guidelines (eg. asymptomatic pathway) were more likely to be younger, healthier and living in less deprived areas, and they tended to be diagnosed at an early stage with a short diagnostic interval. Patients who were female, older, living in more deprived areas and with more comorbid disease were more likely to go through pathways that were divergent from those guidelines. The length of the diagnostic interval was correlated to the
number of colorectal cancer diagnosis-related visits occurring during the interval. All examined factors and the diagnostic interval were significantly associated with the pathway categorization (p<0.0001).
Conclusions: This study demonstrated substantial variations in colorectal cancer diagnostic pathways in Ontario. Interventions should be designed to provide individualized and more effective diagnostic services to patients.

abstract: M.Sc.


title: Macromolecular Orientation of Rigid Dumbbells in Shear Flow

contributor:
Giacomin, Alan
Chemical Engineering

subject:
Orientation Distribution Function
Rigid Dumbbell Model
Simple Shear Flow
Oscillatory Shear Flow
Pattern
Higher Harmonics
Power Series Expansion
Diffusion Equation
Molecular Wobbling
Molecular Tumbling

abstract: We use molecular modeling to study the non-equilibrium behaviour of polymeric fluids. Specifically, we explore the macromolecular orientation induced by shear flow fields. We choose the simplest molecular model, the rigid dumbbell model, which describes the molecular structure of the polymer with two identical spherical beads joined by a massless fixed rod. For rigid dumbbells suspended in a Newtonian solvent, the viscoelastic response depends exclusively on the dynamics of dumbbell orientation. The orientation distribution function ψ (θ,φ,t) represents the probability of finding dumbbells within the range (θ,θ+dθ) and (φ,φ+dφ). This function is expressed in terms of a partial differential equation called the diffusion equation, which, for any simple shear flow, is solved by postulating a series expansion in the shear rate magnitude. Each order of this expansion yields a new partial differential equation, for which one must postulate a form for its solution. This work finds a simple and direct pattern to these solutions. The use of this pattern reduces the amount of work required to determine the coefficients of the power series expansion of the orientation distribution function,ψi. To demonstrate the usefulness of this new pattern, we arrive at new expressions for these coefficients up to and including the sixth power of the shear rate magnitude. This work also completes previous findings that ended at the fourth power of the shear rate magnitude. We then use the general results found for any simple shear flow to derive the solution for the special case of large-amplitude oscillatory shear (LAOS). We extend the orientation distribution function to the 6th power of the shear rate amplitude. We arrive at the Fourier solution for each harmonic contribution to the total orientation distribution function, separating each harmonic into its coefficients in and out-of-phase with cosnωt, ψ'n and ψ" n, respectively. We plot, for the first time, the evolving normalized alternant macromolecular orientation, in the nonlinear viscoelastic regime. Moreover, to deepen our understanding of the macromolecular motions, we distinguish and study two types of possible rotations, tumbling and wobbling

abstract: M.A.Sc.


title: Frequency & Magnitude of Helmet Impacts in One Season of Collegiate Football: An Investigation Into the Effect of Session and Position Type

contributor:
Cook, Douglas James
Neuroscience Studies

subject:
Football
Neuroscience
Concussion
Subconcussive
Helmet impacts
Head impacts
Accelerometers
Training camp
Inside of the box
Outside of the box
Practice
Games

abstract:
Background: Concussive and subconcussive head impacts play important roles in long-term brain health. Professional and collegiate football leagues have been taking steps to reduce dangerous and injurious hits during games, and a select few leagues have eliminated contact practices to improve player safety. It has been hypothesized that training camp presents a unique set of circumstances for players, in which they are competing at a high level of intensity and are vying for a spot on their team, and are participating in more than one practice per day. However, there has been no research conducted to date that has measured head impacts sustained in training camp. To this end, we explored the relative exposure of helmet impacts during football games, practices, and training camp, and how impact tally and magnitude differ between session types. We also explored the relative exposure of helmet impacts and magnitudes between position types.
Methods: Helmet mounted accelerometers were used to record impacts sustained by collegiate football players through training camp, practices and games for one season. Linear acceleration, rotational velocity, and impact location were recorded for every impact. Impacts were analyzed to determine differences in impact tallies and impact magnitudes for different session types and position types. Players were classified as inside or outside of the box. Players that line up in close proximity to the ball, roughly within 3-5 yards of the line of scrimmage, are considered to be inside the box. Players that begin each play at a distance from the ball or further than five yards from the line of scrimmage are considered to be outside of the box.
Results and Discussion: Impacts occurred at the highest frequency and linear acceleration in games, followed by training camp, then practices. Impacts occurred at the highest rotational velocity in games, followed by practices, with no difference between practices and training camp. Players inside of the box sustained impacts at a higher frequency and magnitude than players outside of the box. Based on our findings, training camp may pose a greater risk to player safety than practices, especially for players inside of the box.

abstract: M.Sc.


title: Sedimentary Midges as Paleoindicators of Deep-water Oxygen Conditions Across a Broad Trophic Gradient in Boreal Lakes

contributor:
Smol, John
Biology

subject:
Chironomidae
Hypoxia
Eutrophication
Deep lake
Paleolimnology

abstract: Cultural eutrophication, the addition of excess nutrients to an aquatic system, is a significant water quality concern that often promotes excess algal growth and deep-water oxygen depletion. Deep-water oxygen also influences internal nutrient loading and is an important parameter used to assess cold-water fish habitat, though long-term data are often unavailable. Chironomid (Diptera: Chironomidae) assemblages have been shown to change with deep-water oxygen concentrations and can therefore be used to reconstruct these missing data sets. This thesis used paleolimnological techniques to analyze inferred whole-lake primary production, sedimentary chironomid assemblages, and inferred volume-weighted hypolimnetic oxygen to determine how cold-water fish habitat has changed through time. I will also examine whether biological recovery after nutrient-targeting remediation was introduced was evident in sedimentary chironomid assemblages. I focused on two lakes with increasing inferred whole-lake primary production (Muskrat and Stoco lakes, Ontario) and one lake with decreasing inferred primary production (Lac Duhamel, near Mont Tremblant, Québec) over time. The majority of change in response to elevated inferred whole-lake primary production is evident in littoral taxa and head capsule concentrations, though oxy-conforming profundal taxa (e.g. Micropsectra) did respond to increased whole-lake primary production. Overall, deep-water oxygen recovery after nutrient-targeting remediation was not evident in the sedimentary chironomid assemblages and that there were generally only subtle responses to elevated whole-lake primary production. Many of our lakes had historically low deep-water oxygen concentrations that were suboptimal for cold-water fish throughout their sedimentary records, with two lakes experiencing modest declines after there were increases in whole-lake primary production. These paleolimnological data can be used to set realistic mitigation targets for deep-water oxygen conditions and cold-water fish habitat restoration.

abstract: M.Sc.


title: Finite Element Analysis of Cortical Shell Contributions to Apparent Stiffness and the Effect of Vascular Apertures in Rat Vertebrae Under Uniaxial Compression

contributor:
Pilkey, A. Keith
Lievers, W. Brent
Mechanical and Materials Engineering

subject:
Finite Element Analysis
Uniaxial Compression
Rat Vertebrae
Cortical Shell
Trabecular Network
Osteoporosis

abstract:
Osteoporosis is a degenerative bone disease that causes an increase of fracture risk. The present method of diagnosing the disease is through a bone mineral density (BMD) scan which neglects bone quality. Due to the complexity of bone, experimental testing is difficult; hence the use of finite element models can assist in understanding deformation behaviour and failure mechanisms. The aim of this study is to construct specimen specific-finite element models to investigate stiffness sharing and axial strain distributions of cortical versus trabecular bone of rat L4 vertebral bodies with and without the inclusion of vascular apertures.
In a previous experimental study, healthy (SHAM), osteoporotic (OVX) and treated osteoporotic (OVX+E) rat vertebrae underwent uniaxial compression while synchronously imaged with a micro-CT machine [1]. For the present study, these images have been processed into 3D FE models.  The ratio of cortical shell stiffness to total vertebral body apparent stiffness was 70.1 ± 4.5% across all models with no significant difference across health conditions. However, since this value is significantly (P<0.01) higher than previously reported values in humans, caution should be taken when extrapolating rat vertebrae behaviour to those of humans.  When viewing the axial strain, it was found that in the OVX models, the trabeculae had statistically significantly lower mean strains but a larger proportion of high strain elements creating more strain heterogeneity. Another confounding issue in these rat vertebrae is the presence of large vascular apertures in the dorsal surface of the cortical shell, that have been shown to be associated with cracks [2]. Additional models were created that removed these holes by virtually filling them in. The apparent stiffness of the cortical shell was found to increase by only 0.5%. Looking at the average axial strain distributions with the removal of the vascular apertures, the trabeculae strains showed minimal change, but the cortical shell experienced a significant (P<0.01) increased average axial strain across all health conditions. These results suggest that failure likely originates in the cortical shell and is affected by the presence of the vascular apertures, before progressing into the reduced trabecular network in the region adjacent to the vascular apertures.

abstract: M.A.Sc.


title: Computer-assisted Assessment and Feedback for Image-guided Interventions Training

contributor:
Fichtinger, Gabor
Computing

subject:
computer-assisted training
image-guided interventions
objective skills assessment
medical education
simulation-based training
workflow analysis

abstract:
To improve patient safety, many surgical and interventional specialties use simulation training. This ensures that trainees have a minimum level of proficiency prior to real patient encounters. During simulation training, it is imperative to assess trainees’ learning curves and instruct trainees how to improve their skills. It is infeasible, however, for expert preceptors to continually monitor trainees during training. As a supplement to expert supervision, computer-assisted training has emerged. This thesis proposes computer-assisted methods for assessment, feedback, and instruction in image-guided interventions training. This thesis makes the following contributions.
1. A comprehensive and methodical review of the literature in computer-assisted assessment methods for image-guided interventions training. The review outlines characteristics by which assessment methods can be classified and identifies tools available to the community.
2. Studies on the development and validation of performance metrics for skills assessment in image-guided interventions. The analysis of hand and arm movements in simulated colonoscopy distinguished between novice and experts. The quantification of the planning process in deep brain stimulation indicated skill and was useful for monitoring learning curves during a training course. In both cases, application-specific metrics formulated in consultation with clinical experts had added value in assessment.
3. Methods for overall skills assessment in ultrasound-guided interventions based on performance metrics. A framework for determining which aspects of an intervention are assessed by which performance metrics was designed and validated in three applications. A method for overall skills assessment using transparent and configurable machine learning was developed. It was shown to both be accurate and provide useful feedback to trainees automatically.
4. Development of a method for automated workflow analysis in ultrasound-guided needle interventions. The method combines domain-knowledge with pattern recognition techniques to provide instruction in real-time. The method achieves accuracy approaching the accuracy attained by human observers.
Automated assessment, feedback, and instruction is feasible for computer-assisted training in image-guided interventions when an expert preceptor cannot be present. In this context, the proposed methods have been developed and validated in real training scenarios. The methods are made available to the community through Perk Tutor (www.perktutor.org), an open-source image-guided interventions training platform.

abstract: PhD


title: Physical Testing and Finite Element Analysis of a Corrugated High-Density Polyethylene Stormwater Arch Under Deep Burial

contributor:
Brachman, Richard
Civil Engineering

subject:
stormwater retention
buried arch
deep burial
soil arching
local buckling
thermoplastic

abstract: The performance of a corrugated, high-density polyethylene stormwater retention arch subjected to deep burial conditions was investigated. Current design methods are based on evaluation of performance under both shallow and deep burial conditions. Although field testing and two-dimensional finite element analyses have been carried out during the development of these arched chambers, there has been an absence of high quality laboratory testing and three-dimensional finite element investigation of the failure mechanism and the ultimate limit state under deep burial conditions. This thesis first presents results from a full-scale experiment of two buried, corrugated, high-density polyethylene arches with a 350 mm rise, 690 mm span, and 150 mm spacing surrounded by uncompacted gravel backfill under simulated deep burial conditions. Both performance during backfill and under simulated deep burial conditions up to an applied pressure of 280 kPa were evaluated. Research quantified the structural performance by the evaluation of limit states, examination of global stability, detection of onset and progression of local buckling, and inferred soil behaviour of surrounding backfill. Performance was dominated by large vertical deflections and through-thickness thrusts, with local buckling beginning under an applied pressure of 220 kPa. Second, a three-dimensional finite element analysis was conducted and validated against the physical measurements. Material nonlinearity of the structure material was represented by an updated viscoplastic formulation to account for lower strain rates, while the surrounding backfill material was represented by a linear-elastic, plastic formulation with a Mohr-Coulomb failure criteria and non-associated plastic flow. The model took geometrical nonlinearity into account as the corrugation geometry responded to the applied pressure. Time-dependent behaviour was noted under constant load holds, particularly during the increments once the ultimate limit state had been reached. The explicit three-dimensional finite element model of the buried arches was able to successfully simulate behaviour measured in the physical experiment. A parametric study was then performed to capitalize on the calibrated analysis and extend this work by performing a series of parametric studies which considered factors including soil and structure material parameters, interface constraints, development of local buckling, backfilling effects, and spacing of parallel arches.

abstract: M.A.Sc.


title: Calculating Strain and Stress in Geomembranes at Gravel Indentations

subject:
Geomembrane
Local strain
Landfill
Local Stress
Gravel indentations

abstract:
New methods were developed, validated and applied to calculate strain and stress in geomembrane liners from the local deformed shape imposed by overlying coarse gravel under vertical pressure. Previous strain calculation methods consider only vertical displacements of the geomembrane or neglect bending effects and, consequently, underestimate the maximum strain.  Here, the geomembrane was assumed to behave as a thin plate that undergoes vertical and lateral displacements during deformation. The vertical displacement is the only measurement required while horizontal displacements are related to the deformed shape by strain compatibility equations and obtained by solution to Airy’s stress function.
A viscoplastic model was developed and verified against data from physical experiments to get new insight of stress and strain developed in the wide-strip tensile test, verify the new strain calculation method, and to convert the calculated strain to stress. An axisymmetric single gravel indentation was created by pushing a machined probe into a geomembrane disc clamped around its perimeter. The new strain calculation method yielded strain in very good agreement (within 4% of the maximum strain) with the numerical simulation of the single gravel indentation test.
 The calculated strains were converted to stress using a direct stress-relaxation method. The method utilizes the fading memory concept where the deformation path is taken to have a minor effect on stress if strains remain constant for some time before calculating stress at the time of interest. The method was verified against, and found to be in good agreement with, stresses from finite element models of gravel indentation problems.
The new strain and stress methods were applied to analyse the deformed shape of a geomembrane from a physical test with coarse gravel above and compressible clay beneath the geomembrane to examine the new insights gained from protection layer testing. Comparison with previous strain calculation methods showed that past simplifying assumptions lead to inaccurate values of maximum strains, location and direction. The stress analysis showed that high tensile strain can be obtained under compressive stresses, and therefore, protection layer design should also consider stresses developed in conjunction with strain.

abstract: PhD


title: Assessing the Contributions of Remote Sensing Data in Geological Site Investigations

contributor: Geological Sciences and Geological Engineering

subject:
Site Investigation
Remote Sensing
Synthetic Aperture Radar
Shadow Correction
Geology
3D Laser Scanning

abstract:
Unforeseen ground conditions can have significant impact on the success of any geological project. Therefore, geological site investigation is an essential component of geological field campaigns. Remote sensing techniques have been used extensively for many geological applications, however, their incorporation into geological site investigations have been slow. A framework is required to demonstrate how remote sensing techniques can be incorporated into conventional site investigation practices. Thus, it is the objective of this thesis to assess the contributions of remote sensing datasets and show how to seamlessly integrate these datasets into practical workflows to compliment conventional methods. Case studies using three remote sensing datasets operating at different spatial scales, close-range laser scanning, airborne optical/LiDAR and Synthetic Aperture Radar (SAR), were used.

A literature review revealed that close-range 3D laser scanning was a useful tool for the morphological study of geological hand-samples and had been widely applied in the fields of paleontology, rock mechanics and sedimentology. A case study was completed to digitally calculate the grain-size distribution of ore minerals using laser scanning, which produced comparable results to those generated using a scanning electron microscope, the current state-of-practice.

The utility of LiDAR reflectance data for improved shadow detection in multispectral images was explored. When combined with the spectral bands as input into shadow classification using Support Vector Machines (SVM), the performance of the classification was improved to greater than 95%. To mitigate the effects of these shadows, four methods of colour correction were tested of which Reinhard’s colour transform performed the best. Shadow mitigation substantially improved subsequent vegetation mapping using the Normalized Difference Vegetation Index (NDVI).

It was investigated whether SAR backscatter intensity data could be applied to monitoring temporal changes in northern Canada. Results showed that this data was suitable for monitoring ice cover seasonality, seasonal flooding and seasonal vegetation growth.

These case studies make evident that remote sensing datasets can be used to enhance geological site investigation. Creation of workflows, in which suitable remote sensing techniques are integrated, for each site investigation application is recommended as future work.

abstract: M.A.Sc.


title: Paragenesis of Gold Mineralization and Integrated Exploration Techniques of the Kiyuk Lake Project, Kivalliq Region, Nunavut, Canada

rights: Attribution-NonCommercial-ShareAlike 3.0 United States

subject:
Gold
Kiyuk Lake
Kivalliq
Kivalliq Region
Nunavut
Exploration Techniques
Paragenesis
Proterozoic
Exploration
Gold Mineralization
Proterozoic Sediments
Breccia
Breccia-Hosted Gold
Stable Isotopes
Geochemistry
Geochem
Till Survey
Till Geochemistry
Amphibole alteration
Calc-silicate alteration
Hearne
Hearne Domain
Western Churchill Province
Kiyuk Group
Hurwitz Group
Hydrothermal

abstract: Exploration for gold in Nunavut has primarily focused in Archean greenstone belts in the north and coastal regions of the territory, resulting in large areas of unexplored terrain. The Kiyuk Lake property is located in the underexplored southwest corner of the Kivalliq Region of Nunavut. Gold mineralization hosted by Proterozoic sediments is rare in the Canadian Shield, so this study endeavors to further the understanding of the enigmatic gold mineralization hosted in such sediments at the Rusty Zone at Kiyuk Lake.  Mineralization is hosted by an immature lithic-wacke cut by thin intermediate dykes that are associated with hydrothermal breccias composed of Fe-carbonate, calcite, calcic-amphibole, Fe-sulphide, and Fe-oxide minerals. Textural and timing relationships suggest that the gold mineralization is post-sedimentary and syn- to post-intrusion of intermediate dykes. Stable isotope thermometry indicates mineralization took place between 450-600oC and geochronological studies suggest that the intrusion and mineralization occurred before or about 1.83 Ga. The mineralizing hydrothermal fluids are postulated to be volatile-rich aqueous solutions exsolved from a source of cooling magmas at depth that interacted with metamorphic fluids, previously in equilibrium with S-rich sedimentary rocks and/or basement rocks. Using basement breaching thrusts faults as conduits, fluid overpressurization along a later normal fault is thought to be the primary cause for the rapid depressurization and temperature decrease that caused Fe-sulphides minerals to precipitate, destabilizing the Au(HS)2- complex and finally depositing gold. Although sub-economic at present, the occurrence of gold in Paleoproterozoic basins such as Kiyuk Lake could signal a new timing of gold deposition for the Canadian Shield; however, exploration is challenged by extensive glacial deposits, limited outcrop, and restricted working seasons. Consequently, exploration must be planned to use integrated techniques to efficiently and effectively evaluate regional targets. Here I show a regional till survey, coupled with geophysical magnetic and gravity surveys and structural interpretation can be used to identify new regional scale targets by statically evaluating target scale and regional scale till surveys in conjunction with multi-element drill core chemistry to determine pathfinder element groups that clearly highlight the Rusty Zone outcropping mineralization and lead to the delineation of new anomalous areas.

abstract: M.Sc.


title: Roles of Arginase-1 in Neural Cells

contributor:
Funk, Colin
Biomedical and Molecular Sciences

subject: Arginase-1

abstract:
Arginase-1 (ARG1) is an essential urea cycle (UC) enzyme that catalyzes the hydrolysis of arginine, proposed to also be involved in pre- and post-natal development and post-injury regeneration of neural cells. Genetic mutations in fundamental regions of ARG1 may cause ARG1 deficiency (ARG1D), a UC disorder (UCD) that results in partial or complete loss of functional ARG1 expression. ARG1D presents with late onset neurological phenotypes in comparison to other UCDs, that include: intellectual and growth retardation, and initial spastic diplegia with progression into paraplegia. Because of prominent arginase-1 expression in the nervous system (NS) during embryonic and post-natal development, subsequent upregulation post-injury to the NS, and unique neurological phenotypes of ARG1D in comparison to other UCDs, we hypothesized that ARG1 has pivotal neurobiological roles.
To investigate this, we crossed nestin-cre and Arg1 loxP-flanked mouse strains, effectively creating neural (n)Arg1 knockout (KO) mice, which should congenitally lack functional arginase-1 expression in neural cells. Cre-loxP recombination of Arg1 was determined by PCR genotyping and characterization of the mouse model included protein and mRNA expression analysis of various tissues to confirm NS specific KO of arginase-1. Subsequently, nArg1 KO mice were compared to control mice for assessment of body weight, blood amino acid levels, and stride gait cycle utilizing DigiGait Imaging Systems during 8 to 26 weeks of age. To assess the role of Arg1 post-injury in neural cells a sciatic nerve crush injury (SNCI) model was used. Functional tests were carried out to assay differences in axon reinnervation by assessing return of lost motor and sensory function of nArg1 KO mice compared to control mice. Results suggest no temporal differences in axon reinnervation post-SNCI based on the rate of return of sensory function. Gait abnormalities reminiscent of those observed in ARG1-deficient patients were absent. Our results suggest that an absence of Arg1 in neural cells does not contribute to the phenotypes of ARG1 deficiency, nor is Arg1 likely to be crucial for post-injury axonal regeneration in this particular model, although return of motor function displayed modest delays compared to control mice.

abstract: M.Sc.


title: Assessing Learning Skills and Work Habits in Ontario Secondary Schools

contributor:
Klinger, Don
Education

rights: Attribution-NonCommercial 3.0 United States

subject:
Assessment
Self-regulation
Self-regulated learning
21st Century Skills
Learning Skills
Work Habits
Classroom assessment

abstract: Teachers in all Canadian provinces, and in many jurisdictions around the world, are required to assess elements of student performance other than academic achievement. In Ontario, these assessments are reported in a section of the report card called “Learning Skills and Work Habits” (LSWH). This dissertation examined Ontario secondary teachers’ assessment practice in relation to the LSWH. Empirical data were obtained through interviews, report cards, and an online survey to provide a better understanding of how teachers define, assess, and grade the LSWH. Relationships between LSWH grades and achievement grades, along with gender differences in LSWH grades were also examined. The first study used semi-structured interviews to establish a baseline understanding of teachers’ LSWH assessment practices, and to inform the development of the survey reported in the third study. The second study used Grade 9 and 12 report card grades from two different school districts to establish the dimensionality of the LSWH grades, to find correlations between LSWH grades and achievement, and to examine gender differences in LSWH grades. The third study focused on a single LSWH (self-regulation) and used interview data, report card data from a third district, and survey data to better understand how Ontario secondary teachers conceptualize and operationalize self-regulation. Findings from the three studies indicate a broad range of assessment practices are present in Ontario secondary classrooms, and that teachers make holistic judgements about students’ LSWH and use those judgements to inform their grading decisions. Findings from this research address a critical gap in the classroom assessment literature and are helpful to school systems seeking to improve teachers’ classroom assessment practices.

abstract: PhD


title: Studies on Optically Induced DC-Voltage in Thin Film Structures

contributor: Physics, Engineering Physics and Astronomy

subject: Optical Rectification

subject: Optically-Induced Nonlinear Photovoltage

subject: Hot-electron photodetector

subject: Near-infrared detection

subject: Plasmonic nanostructure

subject: Self-affine nanostructure

subject: Nonlinear optics

subject: Photosensetive device

subject: Rectenna Configuration

abstract:
Conversion of light into direct current is important for applications ranging from energy conversion to photodetection. However, there are still many challenges to reach high conversion efficiency and broad spectral coverage. Overall, photodetection through conventional procedures is based on light absorption by a material with a matching bandgap. This traditional approach limits the range of wavelengths that can be detected, it is not sensitive to polarization, and loses accuracy in the infrared range because of thermal noise. In order to design and optimize a photodetector that can overcome those limitations, I first built an instrument to evaluate the functionality of the proposed devices. Different devices and structures were fabricated and tested by means of photodetection in order to clearly identify the origin of the detected photovoltages. Further investigations on rectenna configurations and nonlinear optical rectification process showed promising results for photovoltage generation in a broadband scheme.
A photodetector that combines polarization sensitivity and circularly polarized light sensitivity in the near infrared region was fabricated using an ITO-Au hybrid layer. Furthermore, the sensitivity of the device was significantly increased by adding a poled molecular-glass film in a capacitor configuration. The resulting device is capable of detecting light below the ITO-bandgap at ambient temperature without any bias voltage. It does not rely on the photoelectric effect, which is at the origin of the photovoltaic effect in semiconductor devices. It works based on hot electron emission in plasmonic nanostructures. This photodetector, which is amenable to large-area fabrication, can be integrated with other nanophotonic and nanoplasmonic structures for operation at telecom wavelengths.
I then show how an array of aligned plasmonic nanorods covalently coupled to molecular rectifiers can also be used as optical nanoantennas to harvest the light and convert it into a DC-potential difference, which may be practical for energy production. I discuss the design, rectification processes, and propos two antenna fabrication procedures: electrochemical deposition and e-beam lithography.

abstract: PhD


title: Testing a Cultural Humility Based Measurement Tool for Sexually and Gender Diverse Positive Spaces in Ontario Public Health Units

contributor:
Goldie, Katie
Nursing

subject:
Public Health
Nursing
Cultural Humility
Positive Spaces

abstract: Background: Sexually and/or gender diverse persons face discrimination and marginalization within and beyond the health care system due to their sexual orientation and/or gender identity. These experiences can lead to poor health outcomes and negative coping strategies. In Ontario, public health nurses (PHNs) could reduce such health inequities by changing their practice and by influencing change within their local public health agencies. Fostering positive spaces using a cultural humility approach is a means through which PHNs could render public health unit spaces safer for sexually and/or gender diverse persons, however; there is a lack of valid and reliable tools for PHNs to assess a cultural humility approach to positive spaces. Purpose: The purpose of this thesis was to advocate for a shift in practice away from cultural competence and towards cultural humility and to test the validity and reliability of modified versions of the Ontario Public Health Association’s (OPHA) personal and workplace tools for perceptions of sexually and gender diverse positive spaces within Ontario public health units.  Methods: The existing OPHA tools were modified based on literature review findings and a cultural humility approach. The tools were tested for face and content validity with a group of expert panelists (N=5) and with Registered Nurses (RNs) (N=5) providing direct services to clients and community partners in public health. To test for construct validity and internal consistency, a cross-sectional online questionnaire was delivered to 1 978 RNs working in public health through email and mailed invitations. Results: An exploratory factor analysis (EFA) of the personal tool (N=259) yielded 40-items with a 15-factor solution; 12 factors had a reliability rating of moderate to excellent. An EFA of the workplace tool yielded a 38-item tool with 10 underlying dimensions; eight of these factors had a reliability rating of moderate to excellent. Conclusion: Evidence-informed improvements have been made to the OPHA positive space tools. Study findings offer an initial reference point for the underlying structure of positive spaces in Ontario public health units. These tools, with further improvements and testing, could be used to inform positive space testing in public health units.

abstract: MNSc.


title: Mathematical Modeling of Nylon 6/6,6 Copolymerization

contributor:
McAuley, Kim
Chemical Engineering

subject:
nylon 6/6,6 copolymerization
mathematical model
polyamide

abstract:
This thesis develops a mathematical model for the hydrolytic copolymerization of caprolactam with hexamethylene diamine (HMD) and adipic acid (ADA) in a batch reactor to produce nylon 6/6,6 copolymer. The reaction mechanism includes hydrolysis of caprolactam and cyclic dimer, polycondensation, polyaddition, transamidation, and ring formation via end biting and back biting. The catalytic effect of carboxyl end groups on reaction rates is accounted for using kinetic and equilibrium parameters from the literature. This model can predict dynamic changes in concentrations of water, caprolactam monomer, comonomers, aminicaproic acid, end groups and degree of polymerization. This model is used to simulate laboratory-scale nylon 6/6,6 batch copolymerization at conditions of industrial interest.
To account for the complex influence of water on nylon reaction equilibria, semi-empirical expressions are developed to describe the equilibrium behaviour for the five dominant reactions that occur during nylon 6, nylon 6,6 and nylon 6/6,6 polymerizations. These expressions are developed by considering additional side reactions involving amidine ends, cyclopentanone ends and hydrated carboxyl ends. A subset of these side reactions is also used to extend the rate expression for polycondensation to account for the influence of water on the overall polycondensation reaction. The kinetic and equilibrium parameters in the updated model are estimated using a large body of literature data values that cover a wide range of operating conditions in nylon 6 and nylon 6,6 homopolymerizations. The updated model and new parameter estimates result in good fit to all of the kinetic data. The objective function value for parameter estimation is reduced by 70% compared to its value using parameters of Arai et al. The predictions for linear monomer and end-group give the most improvement in fit.
The proposed models and improved parameter values in this thesis will be helpful to guide nylon 6/6,6 experiments and to assist with improved understanding of nylon 6, nylon 6,6 and nylon 6/6,6 polymerization processes.

abstract: PhD


title: Characterization of Variants of Unknown Significance (VUS) in BRCA1

contributor:
Davey, Scott
Pathology and Molecular Medicine

subject:
BRCA1
Breast Cancer
Ovarian Cancer
Variants of Unknown Significance

abstract:
Approximately 3%-8% of breast cancer patients carry one defective BRCA1 or BRCA2 allele. While the rise of genetic testing have helped identify BRCA mutation carriers, the implication of certain mutations are still unknown. These comprise almost one third of all BRCA variants. These Variants of Unknown Significance (VUS) pose a challenge for clinicians and patients, since a VUS cannot guide treatment or prevention strategies. To solve this problem, our laboratory previously developed and validated a biological assay using gene expression data from EBV-transformed cell lines.

This study adapted the previously validated assay for use in the clinic by converting to the NanoString nCounter platform and refining the classifier with k-TSP. The classifier was then applied to cell lines derived from individuals carrying novel BRCA1 variants to provide evidence for the pathogenicity of BRCA1 VUS. The overall accuracy of the resulting classifier was 92%. This classifier’s accuracy in the test set of samples derived from patients of KGH with known BRCA1 pathogenicity was 71%.

This classifier provided potentially novel findings about two BRCA1 VUS: c.2050C>T and c.693G>A. All replicate samples tested from patient 43791 (c.2050C>T) and patient 43901 (c.693G>A) had a consensus prediction as not pathogenic. While these predictions provide new evidence towards better characterizing these BRCA1 VUS, they should remain as supplemental evidence that should be used in conjunction with evidence from other sources. Further validation incorporating additional samples is necessary to move this assay forward towards clinical implementation.

abstract: M.Sc.


title: The Locations and Drivers of Herpetofaunal Wildlife Road Mortality on Two Highways within the Frontenac Arch, Ontario

contributor:
Danby, Ryan
Environmental Studies

subject:
Road Mortality
Conservation
Wildlife
Herpetofauna
Frontenac Arch

abstract:
The mortality of wildlife on roads is an aspect of biological and environmental degradation that is often overlooked amidst the plethora of other threats that exist. Yet it is a very real concern, especially for species that are more susceptible to death on roadways, such as the herpetofauna. In this research, I utilized databases of herpetofauna road mortality from two highways in the Frontenac Arch region in eastern Ontario. Data from regular surveys I conducted on a 38km section of Ontario’s Highway 2 (2016 and 2017), as well as previous surveys conducted on the 37km Thousand Islands Parkway (2008 and 2010) were used to explore where and why mortality is occurring in this area.
Kernel density analysis for the taxonomic groupings included in this research showed that road mortality was not random along the roads and there was spatial clustering in the form of hotspots. The hotspots of every taxonomic group overlapped in the middle of Highway 2, while hotspots on the Thousand Islands Parkway were more variable. There is an expanse of forest and wetland that intersects with the hotspot areas of Highway 2, and there was some activity on the Parkway where the road intersects this forest and wetland, but mortality is not as significantly clustered as on Highway 2.
Regression tree analyses showed that, across roadways, wetland and water-related variables are important factors influencing the location of frog and toad, turtle, and watersnake mortality. An overarching trend from the results of the regression tree analyses was that mortality was generally higher in areas with lower traffic levels and in areas lacking development such as roads and urbanization. This suggests that populations in these areas may be avoiding roads, or are depressed due to prolonged exposure to roads and high traffic.

abstract: M.E.S.


title: Measuring the Effect of Concentrate Mineralogy on Flash Furnace Smelting Using Drop Tower Testing and a Novel  Optical Probe

contributor:
Davis, Boyd
Mining Engineering

subject:
Pyrometallurgy
Copper
Flash Furnace Smelting
Optical Emission Spectroscopy
Drop Tower

abstract:
The selection of furnace operating parameters during the flash smelting of copper is based on the elemental composition of a blend and does not account for mineralogy, which may impact on the process. Thus, it is important to study the impact of blend mineralogy on flash combustion processes. This thesis investigates the impact of pure minerals, chalcopyrite and pyrite, on the flash combustion behaviour of three mineralogically distinct but chemically similar copper concentrates through experimental test work. In tandem, proof of concept testing of a novel fibre optic probe for monitoring flash combustion reactions was done.
	A drop tower reactor was used to study the effect of O2/S stoichiometry on flash combustion processes under 21 different test conditions. Tests were conducted at 950oC with O2/S stoichiometries in the range of 0.8 to 4.0, and a solids feed rate of 3 grams per minute. The results suggest that concentrates with low pyrite mineralization require a higher O2/S stoichiometry to be desulphurized to the target matte composition, and that the O2/S stoichiometry impacts the fraction of dust in the products, the flame temperature as well as the flame brightness. In this work, the impact of mineralogy on flash combustion processes is studied using different monitoring techniques to gain real-time information about the process. Ultimately this information may then be used to optimize the blending process and to adjust the operation of a flash furnace in real time.
	Monitoring of combustion reactions was done using emission spectroscopy, where the spectra were acquired through a custom-built fibre optic probe. The two-wavelength method was used to measure the temperature of combusting particles and the integrated intensity was used to measure the flame brightness. This information was found to be useful for identifying feed distribution problems, which are also experienced in commercial scale furnaces. There were no atomic or molecular Cu, Fe, S nor O emission lines or bands in the emission spectrum; however, alkali metal emissions from Na, K and Li were observed. The lack of Cu, Fe, S and O emissions is attributed to the low flame temperatures, which were between 900 and 1500oC. Testing of the sensor in a commercial scale furnace is recommended and is expected to expand the application range of the probe.

abstract: M.A.Sc.


title: De Quincey and the Christian Experience: The Feeling of Struggle, Depravity, and Doubt

contributor:
Morrison, Robert
English Language and Literature

subject:
De Quincey
Romanticism
Christianity
Drugs

abstract:
Abstract

The essayist Thomas De Quincey (1785-1859) produced texts that span the literary periods the Romantic and Victorian and a major shift in the Church of England: he was an Evangelically educated youth and an emerging author when Evangelicalism was a sect, the 1790s-1830s, the Romantic period; and he was an established author when moderate Evangelicalism was the dominant force, the mid-1830s-1850s, the Victorian period. This dissertation argues that Romantic Evangelicalism and the belief in the divine component of the self, which would become central to Victorian Evangelicalism, shape De Quincey’s interpretation of the Christian experience. Like Romantic Evangelicalism, he situates depravity as the essential consideration; he extends the divine to humans, like Victorian Evangelicalism; and he identifies the struggle between the depraved and the divine components of the self as a defining characteristic of the Christian experience, establishing a duality that emphasises depravity in a way that approaches Romantic Evangelicalism. The body chapters contend that if De Quincey employs a version of Romantic Evangelicalism’s interpretation of the Christian experience—experience as the feeling of struggle, depravity, and doubt—key texts will be marked by the absence of the divine component and the positive experience of God’s love, and they will contain doubt about the self, other humans, and a loving God. These key texts include the texts on Christianity (1839-1846); the texts on the literature of power, “Letters to a Young Man Whose Education has been Neglected” (1823) and “The Works of Alexander Pope” (1848); the famous autobiographical texts, Confessions of an English-Opium Eater, “Suspiria De Profundis,” and “The English Mail-Coach”; the ground-breaking texts on Samuel Taylor Coleridge (1834-1835); and the texts “Joan of Arc” (1847) and “The Nautico-Military Nun of Spain” (1847), which he ranked highly among all his texts. The body chapters also consider the role of addiction in shaping De Quincey’s interpretation of the Christian experience. The second chapter addresses Evangelical education, the third the literature of power, the fourth the civil war of the self, the fifth doubt in a loving God, and the sixth despair at and hope in Providence.

abstract: PhD


title: The Bachelor of Health Science Online Program: a Look at Program Development Through the Eye of the Curriculum Committee Members

contributor:
Stockley, Denise
Education

subject:
Competency-based education
Online Education
Health Science Education

abstract:
Delivery of an online education model is a trend that is increasing in popularity in today’s day and age. Although not a recent phenomenon, the technological development within the world of distance education would make it appear as so (McGorry, 2003). Due to the costly expense of university programs and the nature of full-time studies, many students are unable to participate in the traditional in-house university experience (Rasmussen, Northrup & Colson, 2016). Because of this, a large demographic lacks the ability to gain acceptance into professional schools, specifically in health related fields. Offering an online health studies’ program would eliminate this barrier.
When developing an online undergraduate program in health studies, it is imperative to maintain a high degree of academic quality. The purpose of this study was to examine the influences of the curriculum on the development of Bachelor of Health Science (BHSc(H)) online program at Queen’s University, through the eye of the curriculum committee members.
Employing a phenomenological inquiry methodology, data was collected through semi-structured interviews with a total of 14 participants who were members of the curriculum committee. The data was transcribed, analyzed and coded. This analysis revealed four major themes: program design, role of the curriculum committee in the program, online program development and innovation, and course development. Differences in the participants’ perceptions tended to reflect the varying roles they played in the development of the program.
The main influences on the program design included; the use of a backward design model in which assessments were at the forefront of course development and the intricate mapping of competencies and outcomes. The backward design model was considered to be a very effective approach to development of each individual course and set the stage for the high academic quality of the program. In addition, the unique competency-based framework upon which the program is built allowed the developers of the BHSc(H) program to create something innovative and new to the world of online learning across Canadian universities.  Competency-based education is not commonly found at the undergraduate level and will give the successful BHSc(H) program graduates an edge above their peers in postgraduate studies in the healthcare field.
Despite the challenges faced by the program from the get go; fighting against the stigma of online learning, developing traditional hands on assessments in an online format and convincing the graduate schools of the academic quality of the four year online degree, the program development was thorough, rigorous and academically sound. Participants concluded their interviews by outlining their thoughts on the potential success of the program to which they stated that the BHSc(H) program has the potential to be a highly successful route to post graduate studies and to shape the way for future online programs. This program design model might well lead the way for the development of future online programs at Queen’s and across the country.

abstract: M.Ed.


title: Co-regulation of the Cytochrome P450 24A1 gene in a model of kidney fibrosis by 1,25-dihydroxyvitamin D3 and growth factors

contributor:
Petkovich, Martin
Pathology and Molecular Medicine

subject:
vitamin D
CYP24A1
Kidney Fibrosis

abstract: Renal fibrosis is a dominant pathological characteristic of progressive Chronic Kidney Disease (CKD). Epithelial-to-Mesenchymal-Transition (EMT), triggered by tissue damage, caused by renal inflammation, initiates and expands interstitial renal fibrosis. Renal fibrosis can, in turn, cause abnormalities in vitamin D and mineral metabolism, and therefore CKD patients are often vitamin D- deficient and hyperphosphatemic. Treatment of CKD patients with 1,25-dihydroxyvitamin D3 (1,25D3, the active form of vitamin D) has been shown to ameliorate fibrosis, but it can also cause hypercalcemia and possibly exacerbate vascular and soft tissue calcification. We have hypothesized that, due to the longer half-life of calcifediol, or 25-hydroxyvitamin D3 (25D3), and the feedback-controlled activation of this prohormone, treatment of renal fibrosis in a murine Unilateral Ureteral Obstruction (UUO) model would suppress renal inflammation and fibrosis without inducing hypercalcemia. We have treated UUO mice by subcutaneous injection of 25D3 and 1,25D3, and compared their effects on suppression of renal fibrosis, using histological and molecular parameters, for one or two weeks, and monitored various markers of fibrosis and inflammation. Treatment of UUO mice kept on a normal diet with 25D3 significantly suppressed the expression level of the major fibrotic and inflammatory markers without inducing hypercalcemia. If the animals were kept on a vitamin D-deficient diet, the expected anti-fibrotic effects of vitamin D treatment were not achievable. Also, through in vitro studies, the regulatory effect of the inflammatory and fibrotic factors TGFβ1, TNFα, and FGF23 in the presence and absence of 1,25D3, on the expression level as well as regulation of Cyp24a1 (the vitamin D catabolizing enzyme) promoter construct were examined. These studies revealed that TGFβ1 and FGF23 in the presence of vitamin D could induce synergistic upregulation of the Cyp24a1 mRNA, and Tnfα in the presence of vitamin D abrogated upregulation of the enzyme with 1,25D3. Further mutational analysis of the hCYP24A1 promoter confirmed the significant role of major DNA binding elements for the transcriptional effects of TGFβ1 and FGF23.

abstract: PhD


title: Limits of "Truth and Reconciliation": The Effects of compensation on stories about residential schools and Japanese Canadian internment

contributor:
Srivastava, Sarita
Sociology

subject:
Truth and Reconciliation
Indian Residential Schools
Japanese Canadian Internment
Reparations
Compensation
Settler Colonialism
Transitional Justice
Truth-telling

abstract: This thesis problematizes truth-telling about historical injustices in the settler state context of Canada. Truth-telling, in the field of transitional justice, is a survivor-centred process that is typically facilitated by truth commissions to generate a new historical record about a previously denied historical injustice. Truth-telling and compensation are often coupled as reparations for an historical injustice. Within the transitional justice framework, these two measures fall under the “Right to Know” and the “Right to Reparation” respectively. Extending studies of (settler) governmentality (Foucault 2009; Monaghan 2013; Walters 2012) and theories of Indigenous resurgence and decolonization (Alfred 2005; Coulthard 2014; Simpson 2011a, 2016a; Tuck and Yang 2012), this research finds compensation works against the truth-telling of survivors by erasing key aspects of historical injustice within the records of the Canadian civil service. I make this broad argument through three sub-claims. First, I argue that compensation influences the development of new historical narratives. Through Japanese Canadian redress, I demonstrate how Canada’s Public Accounts re-articulates compensation to survivors as a benevolent act of government and trace such benevolence to (settler)colonial dispositions towards Indigenous populations. Second, through the Common Experience Payment to residential school survivors, I find that compensation application forms and program evaluations are two sites which produce silences about historical injustice and survivors by rearticulating these as service delivery to target populations and for all Canadians. Third, I contend that the liberal and nation-building transitional justice framework, within which reparations are being increasingly conceptualized for addressing Indigenous rights, is incommensurable with reparation in the form of decolonization, despite efforts to articulate it as such. This thesis offers insight into the rationalities of government that are used to address the historical injustice claims of survivors and sounds a voice in the space of the silences which compensation processes produce in the records of the Canadian civil service.

abstract: PhD


title: Design of Uniformly Textured Polymer Surfaces for Hard-soft Bearing Systems

contributor:
Bryant, Tim
Mechanical and Materials Engineering

subject: Surface texturing

subject: Finite element analysis

subject: Stress shielding

subject: Total joint arthroplasty

subject: Ultra-high molecular weight polyethylene

subject: UHMWPE

subject: Total knee replacement

subject: TKR

subject: Dimples

abstract:
The aim of this study is to investigate the effect of surface texturing for improving the tribological performance of metal-ultra high molecular weight polyethylene (UHMWPE) bearing systems during intermittent stop-dwell-start (SDS) motion. Numerical and experimental studies were conducted to analyze the role of texture parameters for hemispherical segments (dimples) on the tribological characteristics of two lubricated surfaces in contact, with the objective to minimize contact stress in the polymeric component.

A finite element study was undertaken to determine the effects of three texture design parameters: dimple diameter, d, dimple centre-to-centre spacing, c, and contact area radius, a. Results indicated that lower stress values were evident in the region between dimples. When dimple features were distributed with the centre-to-centre spacing from 20% to 60% of the dimple diameter, the polymeric contact stress was reduced by 10%-45% compared to the average stress without texturing.

In a second study, a computational technique was proposed to calculate the desired dimple stress, σd, for given contact region radius, a, average applied contact load, F, dimple diameter, d, and dimple spacing ratio, c/d. It was demonstrated that an efficient dimple texture design could be realized through an optimal combination of the texture spacing ratio, contact region radius and dimple diameter. It was observed that the contact stress in the plastic region is only dependent on the dimple spacing ratio, c/d, for a given load. However, dimple stress increased as the dimple diameter is enlarged for a fixed contact area and spacing ratio, c/d.

In the final study, a method to fabricate textured surfaces is described that uses hot embossing. The protocol was optimized to produce textured test samples that achieve 95.6% of their target dimensions. Pilot studies of pressure distribution under quasi-static load using a flat cylindrical punch show trends consistent with model predictions.

The results from this work have clinical relevance in the selection of dimple dimensions and lubrication fluid for application in total joint arthroplasty design. However, future studies should consider the effects of lubricant fluid viscosity and the change in material properties of UHMWPE with hot embossing.

abstract: PhD


title: Analysis of Radio Spectral Indices in the CHANG-ES Galaxy Sample

subject:
radio spectral index
galaxy
CHANG-ES

abstract:
The spectral index of a galaxy provides insight on the processes occurring within the galaxy, and can give hints to how the cosmic ray electrons propagate through the galaxy. Band-to-band spectral index maps provide a method for seeing features within a galaxy that are not visible in the in-band spectral index maps due to the increased signal to noise ratio. With data from the CHANG-ES project 126 observed band-to-band spectral index maps have been made from the 35 galaxies in the sample. These maps are created by taking advantage of the matching resolutions of the C-array
L-band and D-array C-band data sets, as well as the B-array L-band and C-array C-band sets. The band-to-band spectral index maps assume a straight line in log space from the L-band to the C-band, thus increasing the signal to noise ratio in the maps but ignoring any curvature within the bands. Further, using the method by Vargas et al. (2018), thermal prediction and non-thermal band-to-band spectral index maps have been created for 22 of the 35 galaxies in the CHANG-ES sample. This is the largest set of spatially resolved maps of its kind.
From this set of maps we have concluded that the spectral index steepens towards the edges of a galaxy as the cosmic rays propagate away from their source and experience energy losses. We find that nearly all of the galaxies have a mean non-thermal spectral index that falls within the observed range of -0.5 to -1.1. We have also produced some of the clearest images of the jets in NGC 660 that have ever been seen. These jets are not even visible in the total intensity radio maps. The maps produced for this thesis will be released to the public for further analysis in an upcoming data
release by the CHANG-ES collaboration.

abstract: M.Sc.


title: Negative Feedback-Seeking in Depression: Examination of Maladaptive Schemas and Rumination as Cognitive Mechanisms, and the Prospective Prediction of Interpersonal Stressful Events

contributor:
Harkness, Kate
Psychology

subject:
Negative Feedback-Seeking
Depression
Maladaptive schemas
Rumination
Interpersonal stressful events

abstract: Coyne’s (1976) interpersonal theory of depression describes a process through which depressed individuals communicate with others such that aversive aspects of their interpersonal behaviour can exacerbate or maintain their depression. Swann’s self-verification theory (Swann, 1983; Swann, 1987) proposes that one such behaviour, negative feedback-seeking (NFS), is the solicitation of negative self-relevant information from others that confirms their negative self-views. Research has demonstrated an association of NFS to depression; however, the cognitive structures that account for this relationship have yet to be empirically tested. In the context of an interpersonal laboratory stressor, the first goal of the present study was to examine the mediating role of rumination and negative self-schemas in the relation of depression to NFS in a sample of 61 participants with diagnosed major depression and 61 non-depressed participants. The second goal was to improve our understanding of how NFS prospectively contributes to negative outcomes – specifically, to interpersonal stress and the exacerbation of depression. Participants underwent a diagnostic interview to determine depression status, and they completed measures of NFS, rumination, negative self-schemas, and depressive symptoms. Participants returned to the lab three months later to complete a contextual interview retrospectively assessing stressful interpersonal events in the interim three-month period and to re-assess depressive symptoms. The results showed that particular negative self-schema domains (i.e., Impaired Limits; and Over-Vigilance & Inhibition) mediated the depression-NFS relation. Rumination was not a significant mediator; however, rumination interacted with the Impaired Limits domain to moderate the significant mediation of Impaired Limits on the relation between depression and NFS, such that the mediation was significant only at moderate and high levels of rumination. With respect to negative outcomes of NFS, the present study did not find that NFS prospectively predicted interpersonal stress, nor did depression (a diagnosis of major depression or baseline depressive symptoms) significantly moderate the relation. Finally, consistent with the hypothesis, NFS significantly prospectively predicted increases in depressive symptoms over time, and these relations were significantly moderated by interpersonal stress exposure. These results are discussed in relation to the findings of previous studies and with regard to limitations of the current study.

abstract: PhD


title: Protolith Affiliation and Tectonometamorphic Evolution of the Gurla Mandhata Core Complex, NW Nepal Himalaya

subject:
Himalaya
Tectonics
Geochemistry
Geochronology
Structural Geology
Gurla Mandhata
Core Complex
Gneiss Dome

abstract: Migmatite-cored gneiss domes in the Himalaya are valuable structures that expose the mid-crust, allowing for the investigation of tectonic and structural processes governing the evolution of the Himalayan orogen. Located in NW Nepal, the Gurla Mandhata core complex exposes the Himalayan Metamorphic Core (HMC), a sequence of high metamorphic-grade gneiss, migmatite, and granite, in the hinterland of the Himalayan orogen. Sm-Nd isotopic analyses indicate that these rocks have both Greater Himalayan sequence (GHS) and Lesser Himalayan sequence (LHS) protolith affinity. In-situ U-Th/Pb monazite petrochronology coupled with petrographic, structural, and microstructural observations reveal that the core complex is composed solely of rocks in the hanging wall of the Main Central Thrust (MCT). Rocks from the core complex record Eocene Eohimalayan and late-Oligocene to early-Miocene Neohimalayan metamorphic pulses (U-Th/Pb monazite age peaks of 40 Ma, 25-19 Ma, and 19-16 Ma) along with a pre-Himalayan Ordovician pulse (ca. 470 Ma). The combination of Sm-Nd isotopic analysis and U-Th/Pb monazite petrochronology demonstrates that both GHS and LHS protolith material is captured in the hanging wall of the MCT and experienced Cenozoic Himalayan metamorphism during south-directed extrusion in west Nepal. Monazite ages do not record metamorphism coeval with late Miocene east-directed exhumation, demonstrating that peak metamorphism and generation of anatectic melt in the core complex had ceased prior to the onset of hinterland orogen-parallel extension at ~15-13 Ma. The geometry of the Gurla Mandhata core complex requires significant hinterland crustal thickening prior to 16 Ma, which is attributed to ductile HMC thickening and footwall accretion of LHS protolith material associated with a ramp-flat MHT geometry below the core complex. The Gurla Mandhata core complex shares many structural and tectonometamorphic characteristics with the North Himalayan domes. This thesis demonstrates that isotopic signatures such as Sm-Nd should only be used to characterize lithotectonic units and structural features across the Himalaya in conjunction with supporting petrochronological and structural data. Further, this thesis highlights the necessity for clear definitions of Himalayan metamorphic rocks that can differentiate between their protolith and tectonometamorphic characteristics.

abstract: M.Sc.


title: Improvement of Biofuel Fermentation Processes With Use of Poly(vinyldodecylimidazolium bromide) for In-situ Product Removal

contributor:
Daugulis, Andrew
Chemical Engineering

subject:
n-butanol
Clostridium acetobutylicum
in-situ product removal
polyionic liquids
fermentation
two-phase partitioning bioreactor
biofuels

abstract:
The production of biofuels through fermentation has become increasingly important due to the need for sustainable energy sources.  The fermentation processes of ethanol and n-butanol, by Saccharomyces cerevisiae and Clostridium acetobutylicum, respectively, suffer from end-product inhibition, hindering final product concentrations, volumetric productivity, and product recovery. To alleviate these limitations, in-situ product removal (ISPR) methods can be implemented, via two-phase partitioning bioreactor (TPPB) technology.  This work used a polyelectrolyte absorbent phase, poly(vinyldodecylimidazolium bromide) [P(VC12ImBr)], in TPPB systems for the removal of the target molecules, ethanol and n-butanol, with focus on the latter due to more severe product inhibition and its greater promise as a biofuel.
P(VC12ImBr) was synthesized and characterized for ISPR implementation and was found to have a partition coefficient (PC) and selectivity of 1.1 and 7.2 for ethanol, and a PC of 6.5 and selectivity of 46 for n-butanol.  Characteristics of P(VC12ImBr) were found to be favorable for TPPB implementation, including its density, diffusivity for n-butanol, and complete biocompatibility with S. cerevisiae and C. acetobutylicum.  A differential scanning calorimetry (DSC) scan of P(VC12ImBr) found its melting temperature to be -17°C and a glass transition temperature above 200°C, which can be reduced by plasticization with water. Anion exchange between bromide in P(VC12ImBr) and sulphate and phosphate ions in fermentation medium was observed, however this did not affect its PC or selectivity.
When implemented in ethanol and acetone-butanol-ethanol (ABE) ISPR fermentations, P(VC12ImBr) absorbed target molecules from the fermentation broth, however improvements relative to a control were observed only for the ABE fermentation with the mass fraction of sorbent used.  In the ABE ISPR fermentation there was greater substrate conversion and an increase in volumetric productivity of 76%.
The water + n-butanol + P(VC12ImBr) ternary system confirmed P(VC12ImBr)’s preference for n-butanol by concentrating dilute solutions above its aqueous solubility limit.  To examine n-butanol absorbed by P(VC12ImBr), a 1.5 wt% n-butanol solution was concentrated to 25 wt% n-butanol, which was thermally removed and condensed to show phase separation. The ability of P(VC12ImBr) to concentrate dilute solutions of n-butanol above its solubility limit would allow for an improved n-butanol purification process.

abstract: M.A.Sc.


title: Post-Islamism Redefined: A Genealogy of Political Islam in Iran

contributor:
Husain, Adnan
Cultural Studies

subject: Political Islam, Iran, Governmentality, Shi'ism, Post-Islamism, Velayat-e Faqih, Gill Deleuze

abstract: Challenging the current academic conception of the term “post-Islamism,” this dissertation provides an alternative definition of the concept, having in mind the case of Iran. In contrast to Asef Bayat’s deployment of “post-Islamism,” as a secular rejection of an Islam that informs political consciousness, this dissertation, following Michel Foucault, situates Islamism within a larger genealogy, in order to investigate the relationships between religious and political traditions, from early Islamic eras to modern responses to an emerging Iranian state in the twentieth century. The dissertation specifically argues for a distinction between a statist Islamism and a non-statist understanding of Islam as a political ideology. To interpret this dynamic, Gill Deleuze and Felix Guattari’s characterization of non-statist “war machines” and centralist logics of the State Apparatus, is invoked to help explain how a modernist religious and political ideology and movement like Islamism developed before, during, and after the Islamic Revolution in 1979.  After defining Islamism, through a critical engagement with scholarship on political Islam, the dissertation provides an analysis of the early Islamic antipathy to statism that characterized the community and movement established by the Prophet Muhammad. The dissertation then applies genealogical analysis to the doctrine of velāyat-e faqih that authorized the clerical domination of the Islamic republic. It then examines the formation of the modern nation-state in Iran and the role Iranian Islamism played in its formation and asks questions about how Islamism as a war-machine turned into a State Apparatus. This dissertation then calls for a revival of Islamism and concludes that the consequences of the state appropriation of Islamism have come to necessitate new cultural and political movements which support religious approaches to politics, yet they resist identifying with Islam as an ideology of state domination.  This dissertation, calls the intellectual process of non-statist Islamist revival: post-Islamism.

abstract: PhD


title: Exploration of New Applications of Inductively Coupled Plasma Mass Spectrometry (ICPMS) to Fuel Cell Electrochemistry

contributor:
Beauchemin, Diane
Jerkiewicz, Gregory
Chemistry

subject: Nanoparticle

subject: Flow Injection

abstract:
The electrochemically active surface area of catalysts in fuel cells can be increased using nanoparticles (NPs). To assess their stability, the mass concentration and the size of NPs, along with the portion that is dissolved, must be determined. Inductively coupled plasma mass spectrometry (ICPMS) allows ultra-trace analysis of solutions and, in single particle (sp) mode, can measure the mass of inorganic NPs in aqueous medium. In fact, if the shape, density and composition of the NPs are known, their masses can be converted into sizes, and a size distribution can then be readily obtained. This thesis presents simple ways to extend the capabilities of ICPMS for the analysis of electrolyte and NPs.
Firstly, it demonstrates that spICPMS can accurately characterize synthetic 10-nm Pt NPs and that it nicely complements transmission electron microscopy (TEM), which provides the NPs shape from their two dimensional projection.  For a known shape, spICPMS measures the NPs size distribution much faster than TEM. Secondly, it introduces flow injection (FI) coupled to spICPMS, i.e., FI-spICPMS, which is then validated through the accurate characterization of 60 nm Au NPs standard suspension.  Thirdly, FI-spICPMS is applied for the first time to synthetic Ni NPs and its performance is compared to that of spICPMS, TEM and X-ray diffraction. FI-spICPMS is beneficial over spICPMS as it eliminates the need to measure the transport efficiency and the sample uptake rate in order to determine the mass of NPs.
Fourthly, a correction factor to the transport efficiency is proposed to improve the accuracy of spICPMS based on conventional standard solution calibration for ICPMS instruments exhibiting a significant settling time compared to the dwell time used to measure NPs. The suitability of the correction factor is confirmed through the accurate analysis of standard Au NPs.
Finally, for the first time, mono-segmented flow analysis (MSFA) is coupled to ICPMS to facilitate the analysis of volume-limited and corrosive samples: 0.5 M H2SO4 electrolyte collected during cyclic voltammetry under simulated fuel cell conditions and minute amounts of differentially glycosylated purple acid phosphatase glycoforms.  In the latter case, such amounts were insufficient for analysis by analytical service laboratories.

abstract: PhD


title: How Can Game Developers Leverage Data from Online Distribution Platforms? A Case Study of the Steam Platform

contributor:
Hassan, Ahmed E.
Computing

subject:
Computer games
Steam
Online distribution

abstract:
Developing a successful game is challenging. Prior work shows that gamers are extremely difficult to satisfy, making the quality of games an important issue. Prior work has yielded important results from mining data that is available on the online distribution platforms for software applications, helping practitioners save valuable resources, and improving the user-perceived quality of software that is distributed through these platforms. However, much of the work on mining online distribution platforms focuses on mining mobile app stores (e.g., Google Play Store, Apple App Store). Video game development differs from the development of other types of software. Hence, knowledge derived from mining mobile app stores may not be directly applicable to game development.

In this Ph.D. thesis, we focused on mining online distribution platforms for games. In particular, we mined data from the Steam platform, the largest digital distribution platforms for PC gaming, with over 23,000 games available and over 184 million active users. More specifically, we analyzed the following four aspects of online distribution for games: urgent updates; the early access model (which enables game developers to sell unfinished versions of their games); user reviews; and user-recorded gameplay videos on the Steam platform. We observed that the choice of update strategy is associated with the proportion of urgent updates that developers have to release. Early access game developers can use the early access model as a method for eliciting early feedback and more positive reviews to attract additional new players. In addition, although negative reviews contain more valuable information for developers, the portion of useful information in positive reviews should not be ignored by developers and researchers. Finally, we proposed an approach for determining the likelihood that a gameplay video demonstrates a game bug, with both a mean average precision at 10 and a mean average precision at 100 of 0.91. Our approach can help game developers leverage readily available gameplay videos to automatically collect otherwise hard-to-gather bug reports for games. The results of our empirical studies highlight the value of mining online distribution platforms for games in offering practical suggestions for game developers.

abstract: PhD


title: Catheter Ablation of Symptomatic Atrial Fibrillation: Impact on Physical Activity, Health-related Quality of Life, and Burden of Arrhythmia

contributor:
Glover, Benedict M
Maurice, Donald H
Biomedical and Molecular Sciences

subject:
Atrial fibrillation
Cardiac arrhythmias
Cardiology
Cardiac electrophysiology
Catheter ablation
Physical activity
Quality of life
Intervention
Psychological well-being

abstract:
Background: Atrial fibrillation (AF) is the most common cardiac arrhythmia affecting more than 33 million individuals worldwide. AF may lead to severe complications associated with disabling symptoms that can reduce health-related quality of life (HRQoL) and exercise performance. Catheter ablation (CA) is currently the mainstay of treatment for symptom amelioration and restoration of sinus rhythm (SR) in patients with symptomatic AF. However, despite improvements in HRQoL, it has yet to be elucidated whether functional improvements post-ablation are related to improvements in physical activity and the relation between arrhythmia burden, exercise volume and intensity remains uncertain.
Methods: Thirty-six patients with symptomatic paroxysmal or persistent AF undergoing catheter ablation were enrolled. Patients were provided with an accelerometer which recorded and transmitted physical activity over a 7-day period pre- and post-ablation. At baseline and 3-months post-ablation, a 48-hour Holter monitor was performed and a HRQoL survey using the Atrial Fibrillation Effect on QualiTy-of-life (AFEQT) questionnaire was administered. At 3-months, recurrence was assessed using Holter monitoring and HRQoL evaluation was repeated.
Results: Within this patient cohort, 28% were female (mean age 60±10). Of the 36 (60%) patients undergoing catheter ablation for their symptomatic AF, 30 (83%) had successful procedures and no recurrent episodes of AF/atrial flutter (AFL) or atrial tachycardia (AT) at 3-months follow-up, while 6 (17%) patients had unsuccessful procedures. Overall, there was an improvement in exercise volume and intensity for all patients who underwent catheter ablation, irrespective of procedural outcome. However, significant improvements in physical activity correlates were only observed in patients with successful procedures (p=0.03 and p=0.013 for total step count and moderate-to-vigorous physical activity (MVPA), respectively) at follow-up. Overall HRQoL at 3-months was substantially increased for patients without recurrences of arrhythmia (p=0.04) and not receiving antiarrhythmic drug (AAD) therapy (p=0.03). AF type had a significant effect on exercise parameters (total step count p=0.005 and MVPA p=0.02) as well as echocardiographic parameters (LVEF p<0.0001) at 3-months post-ablation.
Conclusions: Amongst patients with symptomatic paroxysmal or persistent AF, successful treatment with CA led to significant improvements in exercise capacity and HRQoL. Further investigation is warranted to confirm these results in the long-term.

abstract: M.Sc.