title: The Arabidopsis Calmodulin-Like Protein, CML39, Regulates Early Seedling Development and Fruit Formation

contributor:
Snedden, Wayne
Biology

subject:
Calcium Signalling
Plant Development
Seed Dormancy and Development

abstract: Calcium (Ca2+) is one of the most ubiquitous and versatile second messengers in eukaryotes. In the Ca2+ signaling paradigm, cytosolic Ca2+ oscillations, evoked by environmental stimuli, are detected by Ca2+-binding proteins, termed Ca2+ sensors, that help coordinate physiological responses by binding to and regulating the activities of various other proteins. Calmodulin (CaM) is an evolutionarily-conserved eukaryotic Ca2+ sensor involved in many signal transduction pathways. Intriguingly, plants also possess large families of unique Ca2+sensors related to CaM and known as calmodulin-like (CML) proteins. Several CMLs have been implicated in developmental and stress-response signaling but the roles of most CMLs remain unknown.  Among these CMLs, CML39 is of particular interest due to its roles in early seedling establishment. The focus of my thesis was to determine whether CML39 played additional roles in plant development and to also characterize the mechanism(s) underlying CML39-mediated physiological phenomena. Thus, I employed a multi-disciplinary approach to address this question.  Detailed analysis of cml39 T-DNA insertional knockout plants under various developmental stages identified several abnormalities in these mutants. Relative to wild-type (WT), cml39 displayed aberrant germination behaviour, reduced hormone sensitivity in seeds, altered seed coat characteristics, reduced fertility and de-repression of seed maturation genes in seedlings. The pleiotropic phenotype of cml39 mutants confirms that CML39 regulates diverse aspects of plant development. RNAseq analysis of cml39 seedlings revealed broad perturbations in global gene expression and provided some insight into CML39-regulated pathways.  In addition, two trihelix transcription factors, Arabidopsis 6b-interacting 1-like (ASIL) -1 and -2, were found to interact with CML39 in yeast 2-hybrid and in planta split-luciferase protein-protein interaction analysis, suggesting that CML39 may regulate gene transcription in some tissues.  Genetic analysis of cml39 and asil mutants indicated that CML39-ASIL interaction may be responsible for dormancy maintenance in developing seeds and repression of seed maturation program in vegetative tissue. Collectively, the findings presented in this thesis suggest that CML39 plays an integral role in regulation of seed- and fruit development, dormancy induction and maintenance, hormone sensitivity of seeds, and transition from seed to seedling phase, thus emphasizing the significance of this Ca2+ sensor in plant development.

abstract: PhD


title: The Composition of a Child's Physical Activity and Their Cardio-Metabolic Health

contributor:
Janssen, Ian
Kinesiology and Health Studies

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:
Children
Active Play
Organized Sport
Active Transportation
Physical Education
Cardio-Metabolic Health

abstract:
Purpose:  The purposes of this study of 10-13 year old children were to: (1) determine if time spent in different domains of physical activity was independently associated with selected cardio-metabolic risk factors, and (2) estimate whether replacing time in one domain of physical activity with time in another domain of physical activity was associated with changes in cardio-metabolic risk factors.
Methods: 385 children aged 10-13 years were studied. Participants wore a Garmin Forerunner 220 GPS watch, an Actical accelerometer, and completed an activity log for 7 consecutive days during the school year.  Data from these measures was used to estimate average minutes/day spent in active transportation, outdoor active play, organized sport, and curriculum-based physical activity at school. Percent body fat, resting heart rate, and systolic blood pressure were measured using automated equipment.  Isotemporal substitution regression models were used to estimate changes in cardio-metabolic risk factors that occurred when time spent in each domain of physical activity was replaced with an equivalent amount of time in another domain.
Results: After adjusting for covariates, outdoor active play was associated with body fat % (β = -.058, 95% CI = -.095, -.021) and organized sport was associated with resting heart rate (β = -.040, 95% CI = -.071, -.009).  In the isotemporal substitution models, replacing 10 minutes/day of organized sport with outdoor active play was favourably associated with body fat % (β = -.048, 95% CI = -.094 to -.002) and replacing 10 minutes/day of active transportation with organized sport was favourably associated with resting heart rate (β = -.109, 95% CI = -.197, -.020).
Conclusion: These findings suggest that replacing time spent in organized sport with an equal amount of time in active play may have beneficial effects on body fat and that replacing time spent in active transportation with an equal time in organized sport may improve resting heart rate. No significant effects were observed when curriculum-based physical activity was replaced by another domain of activity.

abstract: M.Sc.


title: A Missing Piece: Monasteries as Centers for a Literate Christian Education in Late Antique Palestine

contributor:
Christou, Theodore
Greenfield, Richard
Education

rights: Attribution-NonCommercial-NoDerivs 3.0 United States

subject:
History of Education
Byzantine Education
Late Antique Education
Religious Education
Christian Education
Monastic Education
Monasteries of Palestine
Early Byzantium
Christian Paideia
Monastic Literacy

abstract:
Research into the history of education provides powerful insights for answering a philosophical question of central importance: namely, what is the purpose of education. While recent research has emphasized looking to the past few centuries, investigating the educational practices of ancient societies is also valuable. The education available in the Byzantine Empire is particularly useful to examine. This society existed for a millennium and contributed substantially to the development of many aspects of the world as we know it today. In contradiction to its importance, however, its study has been neglected by historians of education.
The education of the early Byzantine Empire (4th-6th centuries) is particularly interesting to explore, as society shifted in religious belief from pagan pluralism to Christianity. This religious transition led to questions on the nature and purpose of education as compromise was sought between the two religions. Such a struggle for educational compromise parallels contemporary Canadian society, where, as well-attested in the literature, a formerly Christian society is adjusting to one of pluralism and religious tolerance.
Education in the early Byzantine Empire is presented in the literature as the bailiwick of the elite. Even as society Christianized, historians of education emphasize that educational practices remained those inherited from a pagan past. This assertion is complicated, however, by scholars of early Christianity who identify the rise of Christian monasticism and its “educational” capacity. While the pagan educational practices are well described as literary in nature, the means of monastic education is ambiguous.
This study reconciles these two scholarly traditions, drawing on monastic primary sources to describe the literate education available within Christian monasteries of Late Antique Palestine. It then goes further, exploring the impact literate monks had on the Christianization of Byzantine society, and recursively, the impact this newly Christian society had on monasticism.
This thesis contributes significantly to an understanding of the intersection between education and religion. Value is also to be found in the form of education that is revealed – an education not concerned with advancement and worldly gain, but one of self-improvement and spiritual growth.

abstract: M.Ed.


title: Design Optimization of Aircraft Landing Gear Assembly under Dynamic Loading

contributor:
Kim, Il Yong
Mechanical and Materials Engineering

rights: Attribution-ShareAlike 3.0 United States

subject:
Topology Optimization
Aerospace
Multi-Body Dynamics
Landing gear
Aircraft
Design
Finite Element Analysis
Hyperworks
Optistruct

abstract:
As development cycles and prototyping iterations begin to decrease in the aerospace industry, it is important to develop and improve practical methodologies to meet all design metrics. This research presents an efficient methodology that applies high-fidelity multi-disciplinary design optimization techniques to commercial landing gear assemblies, for weight reduction, cost savings, and structural performance dynamic loading. Specifically, a slave link subassembly was selected as the candidate to explore the feasibility of this methodology. The design optimization process utilized in this research was sectioned into three main stages: setup, optimization, and redesign.
The first stage involved the creation and characterization of the models used throughout this research. The slave link assembly was modelled with a simplified landing gear test, replicating the behavior of the physical system. Through extensive review of the literature and collaboration with Safran Landing Systems, dynamic and structural behavior for the system were characterized and defined mathematically. Once defined, the characterized behaviors for the slave link assembly were then used to conduct a Multi-Body Dynamic (MBD) analysis to determine the dynamic and structural response of the system. These responses were then utilized in a topology optimization through the use of the Equivalent Static Load Method (ESLM). The results of the optimization were interpreted and later used to generate improved designs in terms of weight, cost, and structural performance under dynamic loading in stage three. The optimized designs were then validated using the model created for the MBD analysis of the baseline design.
The design generation process employed two different approaches for post-processing the topology results produced.  The first approach implemented a close replication of the topology results, resulting in a design with an overall peak stress increase of 74%, weight savings of 67%, and no apparent cost savings due to complex features present in the design. The second design approach focused on realizing reciprocating benefits for cost and weight savings. As a result, this design was able to achieve an overall peak stress increase of 6%, weight and cost savings of 36%, and 60%, respectively.

abstract: M.A.Sc.


title: Exploring the Evolutionary Relationship Between Virulence and Drug Resistance

contributor:
Day, Troy
Mathematics and Statistics

subject:
Mathematical Biology
Virulence
Drug Resistance
Plasmid
Superinfection
Reproductive Ratio

abstract:
One of the many possible negative outcomes of pathogen evolution is the emergence of a virulent drug resistant strain. A pathogen may exploit plasmid-mediated gene transfer to gain drug resistance and virulence genes in an attempt to become the exclusive infection. To answer questions on the possible emergence of a virulent drug resistant strain we constructed a nine dimensional SIS model with treatment. We used plasmid-mediated gene transfer by way of superinfection to distribute virulence and drug resistance genes. By examining the resulting system of differential equations at the two extremes of treatment level (%0 and %100), we determined the stability of the single strain endemic infection equilibrium points of interest. In the absence of treatment we determined a set of ancestral conditions which provided constraints on the model parameters. In the presence of treatment we focused on the ability of the
virulent drug resistant (AB) strain to invade the avirulent drug resistant (B) strain. We were able to express these invasion conditions in terms of novel reproductive ratios that incorporated both non-superinfection effects and superinfection effects.

Our model reveals that plasmid-mediated gene transfer by way of superinfection increases the parameter space allowing for virulence to evolve in a drug resistant population. However, virulence in a drug resistant population is not always more
likely to evolve in comparison to virulence in a drug sensitive population.

abstract: M.Sc.


title: Transsaccadic Memory of Multi-Featured Objects

contributor:
Blohm, Gunnar
Neuroscience Studies

subject:
Remapping
Visual Memory
Trans-saccadic Perception
VSTM

abstract:
Our visual world is observed as a complete and continuous percept. However, the nature of eye
movements, saccades, preclude this illusion at the sensory level of the retina.  Current theories suggest
that visual short-term memory (VSTM) may allow for this perceptual illusion through spatial updating of
object locations. While spatial updating has been demonstrated to impose a cost on the precision of spatial
memory, it is unknown whether saccades also influence feature memory. This thesis investigated whether
there is a cost of spatial updating on VSTM of non-spatial features. To this end, participants performed
comparisons of features (location, orientation, size) between two bars presented sequentially with or
without an intervening saccade. In addition, dependent on the block condition, they had to compare either
one of the features or all three features; to test for memory load effects. Saccades imposed a cost on
precision of location memory of the first bar in addition to a direction-specific bias; this effect held with
greater memory load. Orientation memory became less precise with saccades, and with greater memory
load resulted in a remembered rotation of the first bar opposite to the direction of the saccade. Finally,
after a saccade, participants consistently underestimated the size of the first bar in addition to being less
precise; the precision effect did not hold with greater memory load. Together, the current findings
implicate a cost on feature memory with saccades – suggesting that non-spatial feature memory is
updated along with their spatial locations.

abstract: M.Sc.


title: The Effects of Intermittent Theta Burst Stimulation on Working Memory in Depressed Patients

contributor:
Milev, Roumen
Neuroscience Studies

subject:
Depression
iTBS
Working Memory

abstract:
Background: People with depression struggle with cognitive impairments such as decreased working memory. The brain areas associated with working memory, such as the prefrontal cortex and hippocampus are negatively affected by depression; studies have shown decreased volume, activity, and disturbed brain connectivity. Currently, there is a lack of treatment options for improving working memory in depressed patients. Therefore, the therapeutic potential of intermittent theta-burst stimulation (iTBS) on working memory was explored. iTBS has been shown to be effective in treating mood, increasing plasticity and inducing neurogenesis. These findings suggest a potential for iTBS as a treatment tool for working memory.

Objective: The objective of the present study was to determine whether iTBS treatment is associated with improvement in working memory, and connectivity changes between areas in the prefrontal cortex, hippocampus and the rest of the brain.

Methods: We recruited 10 patients with major depressive disorder (MDD). Patients received the standard 25 days of iTBS treatment. We used the n-back (2-back) task to test working memory during functional magnetic resonance imaging (fMRI) scan. Participants received a fMRI scan before and after the final iTBS treatment. Participants also completed clinical measures (i.e., depression scales) before and after their treatments.

Results: The participants did not show significant improvements in mood and the n-back task (accuracy and reaction time) after the iTBS treatments. There were significant changes in functional connectivity during the resting state scans and for the 0 and 2 back conditions of the n-back task between various areas including the left hippocampus and the frontal poles with structures such as the caudate, occipital cortex, lingual gyrus and the temporal lobe.

Conclusion: Our pilot study showed that iTBS treatment may not be an effective tool for improving behavioural performance on the n-back task. However, the significant functional connectivity changes suggest that iTBS may be responsible for beneficial brain changes in depressed patients. These changes could be explained by increased efficiency and/or cognitive control in the context of the n-back task. Future research with sham controlled design and different working memory tasks are needed to determine the effects of iTBS treatment on WM.

abstract: M.Sc.


title: Reconfigurable Circuits for Communication Applications and Environment-Aware Receivers

contributor:
Saavedra, Carlos E.
Electrical and Computer Engineering

subject:
Reconfigurable
Environment-Aware Receiver
Active Mixer
CMOS
Phase Shifter
Tunable

abstract:
This thesis explores the new applications which benefi t from the exploitation of the digital circuits in the design of RF circuits. Two main applications presented here are the recon figurable circuits design, essential for the design of optimal power consumption receivers and the boost of a circuit's performance beyond its RF-only design
limits. The concept of the fi rst environment-aware receiver architecture is introduced for the study of the former application along with a novel, recon figurable, highly linear active mixer. The latter application's practicality is studied through the design of an active phase shifter with improved accuracy regarding its RMS phase and amplitude
errors.

The Environment-aware receiver is introduced as a method for achieving an optimal power consumption with the minimum required quality of service of a certain standard. This receiver takes advantage from the use of a channel sensing receiving path to estimate the required phase noise and main linearity merits, IIP3 and P1dB.
A novel highly linear, recon figurable mixer with four states of power consumption and linearity is designed based on the dynamic current injection method, introduced in this work. The mixer is a crucial part of the proper adjustment of IIP3 and P1dB of the environment-aware receiver. A set of switches in the LO and IF stage of the mixer help in the achievement of the recon figurable mixer.  The dynamic current injection method, used in this design is studied and developed using a pair of cross-coupled pMOS devices. This method improves the linearity of the active mixer without increasing the power consumption or any significant deterioration of other important merits of the mixer.

The accuracy of an active phase shifter is improved beyond its RF-only fundamental limits by the use of a  fine passive vector scaling mechanism. While the OTA used in this work introduces large phase gaps and limiting the maximum possible accuracy to 4-bits, the 4-state  ne scaling mechanism improves the possible accuracy to 6-bits without increasing the power consumption of the design.

abstract: PhD


title: Subsurface water flow pathways in the canadian High Arctic

contributor:
Lamoureux, Scott
Geography and Planning

subject:
High Arctic
Subsurface Hydrology
Cryostructure
Preferential flow pathways

abstract: In Arctic regions subsurface flow is often a dominant flow path of water, especially as the thaw depth progresses and the active layer water storage capacity increases. Subsurface flow through the active layer is important for water delivery to streams and can be potentially routed through subsurface preferential flow pathways (PFP). The majority of research on subsurface hydrological PFP has occurred in the subarctic where organic soils and discontinuous permafrost are predominant. Research on such pathways in the High Arctic where mineral soils with minimal organic layer dominate is limited. This thesis investigated the hydrological response during active layer development in a dominantly mineral soil to understand how soil subsurface and surface water interactions are conditioned by the presence and seasonal development of PFP pathways in a headwater subcatchment at the Cape Bounty Arctic Watershed Observatory, Melville Island, Nunavut.  Subsurface flow and PFP were examined through  cryostructure analysis from two active layer cores, and seasonal active layer development.  A network of piezometers was also installed across four land cover types (high and low hummock, mesic slope, polar semi-desert, and an area with established soil pipe drainage) to evaluate hydrological function of preferential pathways. Electrical conductivity (EC) and stable water isotopes were collected from piezometers to further infer subsurface water sources. Results indicate that drainage and saturation of soil from water in the subsurface is spatially and temporally heterogeneous in High Arctic mineral soils. The timing of the activation (effective drainage) and deactivation (termination of drainage) of subsurface water pathways was similarly heterogeneous across the study site. The timing and depth of the activation of pathways demonstrates that varying cryostructure at depth triggered the emergence of substantial water at select locations. Finally stable isotopes indicate that the source of water moving through the subsurface varies spatially and temporally over short distances with seasonal progressions from rain water to snow/ground ice, and vice versa. This knowledge provides primary observations towards understanding subsurface preferential flow pathways in a High Arctic catchment and the importance of PFP on water delivery to streams in the late thaw season.

abstract: M.Sc.


title: Identifying and Monitoring Rockfall Precursors Using Terrestrial Laser Scanning for Improved Rockfall Hazard Management

contributor: Geological Sciences and Geological Engineering

subject:
Rockfall
LiDAR
Terrestrial Laser Scanning
Rockfall Hazard Management
Rockfall Precursors
Near-Real-Time Monitoring
Change detection
Landslide Risk Management
Rock Slope Monitoring
Point Cloud

abstract:
Rockfalls threaten communities and infrastructure in mountainous regions worldwide and have been a particularly problematic hazard along the transportation corridors in western Canada. These types of failures are traditionally managed using rockfall hazard management frameworks that are based on a historical analysis of rockfall activity. These frameworks do not fully consider the complexity of the natural rock slopes, nor indicate where and when a potential failure may occur. Terrestrial Laser Scanning (TLS) has been beneficial for monitoring and assessing rock slope hazards and has the potential to identify incipient signs of rock slope failure.
The aim of this thesis is to use TLS to better manage rockfall hazard along transportation corridors by including quantitative measures of precursor activity into hazard analysis strategies and through the development of near-real time automated TLS systems for early warning purposes.
In the first part of the thesis, monitoring at 2-3-month intervals was conducted with TLS at a variety of rock slopes located along the CN Rail line in the Thompson River valley over the four-year duration of this research. Over one hundred rockfalls in the range of 0.1 to 4200 m3, exhibiting precursor activity in the form of pre-failure deformation, smaller precursor rockfalls and tension crack openings were studied and compiled into a database. The approach included: (i) identifying potential rockfall source zones based on incipient signs of failure; (ii) tracking kinematics in three dimensions to better understand the mechanisms of failure; (iii) estimating potential failure volumes based on bounding joint structure; and (iv) transmitting this information to the railway operator for an assessment of risk.
	The second part of the thesis focused on monitoring at near continuous levels, which is required to identify the accelerating phase prior to rockfall failure which is necessary to forecast failure time in early warning systems. A complete series of analysis tools was developed to process and analyze TLS data autonomously in near real-time.  This included tools to filter outliers, register point clouds, conduct change detection using spatial and temporal neighbourhood averaging and to display time series of deformation. The system was tested for a 6-week period at a rockslide in the French alps.
	The contributions in this thesis (i) enhance current rockfall hazard analysis methods by including quantitative measurements of precursor activity, (ii) improve our understanding of the pre-failure stage of rock slope failures and (iii) opened the door for future studies of rock slope failure at a high temporal density using TLS.

abstract: PhD


title: Flow-Mediated Dilation Induced by a Sustained Shear Stress Stimulus: Repeatability and Impact of Endurance Exercise

contributor:
Pyke, Kyra
Kinesiology and Health Studies

subject:
Endothelial Function
Handgrip Exercise
Brachial Artery
Superficial Femoral Artery
FMD
Vasodilation
Training
Aerobic Exercise
Dilatation
Shear Rate
Endothelium

abstract: The endothelium is a single layer of cells that lines the inside of all arteries, the proper functioning of which is essential for vasoprotection and control of arterial dilation.  Blood flow through an artery produces a frictional force on the endothelium called shear stress, which causes the artery to dilate.  A larger magnitude of this ‘flow-mediated dilation’ (FMD) response indicates greater endothelial function.  To date, FMD has primarily been experimentally assessed using a transient shear stress stimulus called reactive hyperemia (RH).  There is a paucity of research available which assesses FMD using sustained increases in shear stress, which are more similar to the shear stress stimuli that an artery experiences in everyday life.  Therefore, the objective of this dissertation was to further our understanding of the FMD response to sustained shear stress stimuli and how it is impacted acutely and chronically by endurance exercise.  Methods:  Repeated handgrip squeezing (HGEX) and calf plantar-flexion (LEX) were used create a sustained increase in shear stress, stimulating FMD in the brachial and superficial femoral arteries respectively.  1) HGEX-FMD was assessed before and after an acute bout of high-intensity exercise.  The mechanisms of exercise’s effect on HGEX-FMD were interrogated via the consumption of the antioxidant vitamin C.  2) In the superficial femoral artery, the repeat-trial stability of LEX-FMD was compared to RH-FMD.  3) The EX-FMD and RH-FMD responses to 4 weeks of endurance exercise training were assessed in the brachial and superficial femoral arteries.  Results: 1) Brachial artery HGEX-FMD was augmented by high intensity endurance exercise, and this effect was abolished by vitamin C consumption, suggesting a role of oxidative stress in this adaptation.  2) Superficial femoral artery LEX-FMD was shown to increase systematically upon repeated trials, but RH-FMD did not.  3) Training improved brachial artery RH-FMD, but not HGEX-FMD and not LEX- or RH-FMD in the superficial femoral artery.  Conclusions: The FMD responses to sustained and transient shear stress stimuli are regionally different, functionally different, and differently effected by exercise-related interventions, supporting the idea that they measure different aspects of endothelial function.

abstract: PhD


title: Assessment of Steel Truss Bridges Using Distributed Strain Measurements

contributor:
Hoult, Neil
Civil Engineering

subject:
Distributed Strain Sensing
Steel Truss
Fibre Optic Sensors

abstract:
Steel truss bridges are an important component of the railway network across North America. A majority of this infrastructure has already exceeded its 100 year service life, making the monitoring of these structures critical to ensuring they have adequate capacity to handle the increasing freight loads. Visual inspection remains the primary monitoring method because of its cost and time effectiveness. However it can be subjective, produce varying results between inspectors, and is unable to accurately quantify damage or behaviour. The use of distributed fibre optic sensors has the potential to overcome the shortcomings of visual inspection, along with the added benefit of capturing thousands of measurements with a similar effort required to obtain a single measurement with conventional strain gauges.
The current research investigated the use of distributed fibre optic strain measurement to monitor the behaviour of steel truss bridges. A scaled down model truss based on an in service railway bridge was constructed in a laboratory setting. The truss was monitored with both fibre optic sensors and linear potentiometers. The connection conditions were varied by either removing or loosening bolts between vertical and diagonal members. A response change was detected by both sensor technologies when all bolts were loosened versus tightened. Varying degrees of corrosion and cracking damage were simulated on members, and the strain changes in the members were detected using the distributed strain sensors.
An in service rail bridge was monitored and static distributed strain measurements were taken as a train of known weight was placed at various positions along the bridge span. The same train then travelled across the bridge at varying speeds as dynamic measurements were taken. Finally, in service measurements for passenger and freight trains were also taken. The static measurements were used to detect localized variations in strain due to changing member geometry as well as global behaviour. The dynamic strain measurements for a train travelling at 4 km/h showed good correlation to the static measurements, however all dynamic measurements gave inconclusive results beyond the first 10 m of sensing fibre. In service vehicles could not be monitored at their normal travelling speed.

abstract: M.A.Sc.


title: Portable, Droplet-Based Microfluidic Device for Aqueous-Two-Phaseextractions and Colorimetric Detection of Cadmium

contributor:
Oleschuk, Richard
Chemistry

subject:
Digital Microfluidics
Microfluidics
Superhydrophobic
Droplet Array
3D-Printing
Droplet Splitting
Aqueous-Two-Phase-System
Aqueous-Two-Phase-Extraction
ATPS
ATPE
Cadmium
Extraction
Colorimetry
Smartphone
Surface Energy Trap
Spin Coating
Air Plasma
Laser Micromachining
Memory Foam

abstract:
A portable, digital-microfluidic device for aqueous-two-phase-based extractions is presented. Droplets (50 µL) consist of an aqueous-two-phase-system (sodium sulfate and polyethylene glycol) and an extractant (potassium iodide) to move Cd2+ ions selectively from a mixture of metal ions into the polyethylene glycol top phase.
The droplets are confined by hydrophilic surface energy traps on a superhydrophobic substrate that is made of a commercially available coating (Ultra-EverDry™). Surface energy traps are generated by exposing specific regions of the surface to air plasma or by laser micro-machining, where a portion of the superhydrophobic coating is ablated and the hydrophilic glass underneath is exposed. A 3D-printed holder applies another surface energy trap on top of the droplet and
lifts it. This allows one to precisely separate different volumes (0.19-14.91 µL) of the polyethylene glycol top phase depending on the surface energy trap size.
Subsequent addition of an indicator dye to a separated aliquot of the top phase allows interference free, colorimetric detection of Cd2+ ions with a smartphone camera.

abstract: M.Sc.


title: The Effects of Prenatal Prescription Medication Exposure on Neonatal Abstinence Syndrome

contributor:
Brogly, Susan
Peng, Paul
Public Health Sciences

subject:
Neonatal Abstinence Syndrome
Methadone
Buprenorphine
Expression
Growth Curves
Symptom

abstract:
Background: The increased occurrence of neonatal abstinence syndrome (NAS) is a major public health concern within Canada and the United States. NAS is a drug withdrawal syndrome caused by the abrupt cessation of prolonged prenatal exposure to opioids. Because of the increasing number of infants affected with NAS and subsequent increased utilization of hospital resources for NAS, research to improve NAS definition, measurement, and management is needed. This study aims to describe the presentation of NAS in neonates prenatally exposed to buprenorphine vs. methadone.

Methods: We conducted a prospective cohort study of pregnant women with opioid use disorder and their neonates.  Women were treated with buprenorphine or methadone based on clinical indicators and patient preference. Neonates were assessed using the 31-item Finnegan scale and scored every four hours, increasing to every two hours if NAS pharmacotherapy was initiated. Differences in NAS symptoms were compared among 34 buprenorphine-exposed neonates and 43 methadone-exposed neonates prior to and following NAS pharmacotherapy initiation were statistically assessed. Individual growth curve models (IGC) were applied to the Finnegan score data, adjusted for confounders, and NAS trajectories were plotted by prenatal exposure to buprenorphine or methadone.

Results: Prior to NAS pharmacotherapy initiation, four NAS symptoms were observed significantly more often in buprenorphine exposed neonates compared to methadone exposed neonates: continuous high pitched crying (76.5% vs. 32.6%), hyperactive Moro reflex (47.1% vs. 23.3%), nasal stuffiness (42.4% vs. 15.9%), and loose stools (50.0% vs. 23.3 Furthermore, we were able to successfully apply an IGC approach to modeling change trajectories to repeated Finnegan score data. Differences in NAS progression by prenatal opioid agonist therapy exposure were identified in neonates who required NAS pharmacotherapy.

Conclusion: This is one of the first studies to investigate NAS symptom expression by prenatal opioid agonist therapy exposure to buprenorphine and methadone. This study will provide a resource for other researchers to apply these novel procedures which have not been previously used in pediatric research. The findings from this study provide insight into how these two prenatal medications affect NAS symptom expression and NAS progression allowing healthcare professionals to improve NAS definition, measurement, and management.

abstract: M.Sc.


title: Leakage Phenomena of Tailings Overlying a 1 cm Diameter Circular Geomembrane defect

contributor:
Rowe, R. Kerry
Brachman, Richard
Civil Engineering

subject: Geomembrane Tailings

abstract:
Leakage phenomena for two types of tailings overlying a 1 cm diameter geomembrane defect were studied. The first type of tailings was a Silty Sand. Various underliners (DF15/DB85=5.6 to 13.5) not meeting typical retention criteria for filtration were placed beneath the tailings and geomembrane defect. The leakage rates and visual findings revealed that a critical stress condition exists where erosion continuously occurred for up to 24 hours. This condition resulted in a leakage rate that was 2 to 3 orders of magnitude higher than previous observed with filter compatible conditions and higher stresses. This condition could be encountered during early deposition or development of a reclaim pond at a tailings storage facility. Visual findings on the surface of the underliner suggested that contact likely had more influence on stability in this critical stress condition than gradation compatibility. Based on the areal coverage of tailings on the surface of the underliner, it was postulated that more intimate contact between the geomembrane and underliner leads to more stable leakage conditions.

The second type of tailings studied was fine-grained (approximately 90% passing 75 um). The material was placed on top of a geomembrane with a 1 cm defect, overlying a filter compatible underliner. Leakage rates implied the hydraulic conductivity reduced as the tailing experienced more vertical effective stress (up to 200 kPa).  Small samples (8 mm in diameter, 6 mm in height) were retrieved near the defect after the test and permeated at a variety of effective stresses (0 to 800 kPa). Although some disturbance likely occurred, the permeation results suggested the tailings hydraulic conductivity was in the range of 3 x 10-9 to 6 x 10-9 m/s, which confirmed values estimated using a saturated seepage model (SEEP W/). Permeation results and gradation analysis of the small samples suggested that significant migration of fines did not occur. Further seepage modeling assuming homogeneous tailings hydraulic conductivity suggested the leakage rate from a well-designed, well-constructed, lined facility containing the tailings is likely in the range of 1-2 L/ha/day. Without the liner, the leakage rate is likely 3-4 orders of magnitude higher.

abstract: M.A.Sc.


title: Preparation and Characterization of Hydrophobic Graphene-Based Thin Films

contributor:
Docoslis, Aris
Truica-Marasescu, Florina
Chemical Engineering

subject:
Graphene Oxide
Reduced Graphene Oxide
Spraying
Water Contact Angle
Industrial Coating Technology
Hydrophobicity

abstract:
Since the ``Scotch tape" discovery of graphene synthesis over a decade ago there has been significant interest in the industrial scale-up of graphene production, with the understanding that the material's exceptional physical and electrical properties could be used to enhance finished products. One remarkable property of graphene is the degree to which it, an atomically-thin material, can impart hydrophobicity to a surface. Liquid-phase surface treatments are familiar to many industrial engineering practices and it is well-known that graphene oxide, a graphene derivative which can be modified to achieve graphene-like material qualities, disperses well in many solvents. Although graphene oxide is hydrophilic, it can be made hydrophobic by reduction, and perhaps even superhydrophobic with the inclusion of surface topography. Therefore, the reduction of graphene oxide films offers one possible route to graphene's entry to industry as a hydrophobic surface coating treatment.

This thesis begins with an experimental investigation into graphene oxide's dispersibility in different solvents. The influence of these solvents on the physico-chemical characteristics of the resulting graphene oxide and reduced graphene oxide thin films cast on a silicon substrate is studied. It is found that the choice of dispersing medium determines the degree of surface coverage and therefore the degree of film wettability. Subsequently, the chemical nature and hydrophobicity increase that is imparted by a new photoreduction process applied to the graphene oxide-based films is researched. From this, it was observed that the chemistry of the photoreduced films greatly differs from that of the thermally reduced films, including larger quantities of oxygen. The thesis concludes with a brief examination of the degree to which substrate topography can enhance the hydrophobicity of graphene oxide-based films deposited on chemically etched glass. It is found that with the addition of a roughened surface topography the water contact angle can be improved by up to 45°.

abstract: M.A.Sc.


title: Development of a Microinjection Platform for the Examination of Host-Biomaterial Interactions in Zebrafish Embryos

contributor:
Fitzpatrick, Lindsay
Chemical Engineering

subject:
Biomaterial
Zebrafish
Immune System
Microinjection

abstract:
Current approaches in biomaterial development require a series of in vitro and in vivo assays to identify and optimize candidate materials. Current in vitro assays have low labor requirements and are relatively cheap compared to in vivo studies but fail to recapitulate the host response. Alternatively, in vivo models do not provide a wide array of analytical tools, and are labor intensive. Therefore, a gap exists for a model that retains the low labor requirements and cost of in vitro assays, while allowing researchers the ability to observe a true host-biomaterial interaction. Zebrafish have the potential to provide such a model due to their naturally transparency, high fecundity that enables a single female to produce upwards of a hundred eggs a week, and the wide array of transgenic strains.
After establishment of a colony at Queen’s University, microinjection techniques were developed to assess the feasibility of using zebrafish as a model for host-biomaterial interaction using poly(styrene) and poly(ethylene) microparticles with diameters of 10, 25, and 50 μm. Implantation success and retention rates were examined, as well as zebrafish mortality rates out to 30 days post injection (dpi). Successful implantation rates were measured at 33%, 17%, and 12% for 10, 25, and 50 μm microparticles, respectively. Retention rates were identical for 10 and 25 μm microparticles at 78%, but implant retention was 11% for 50 μm microparticles. Furthermore, 10 μm microparticles injected with 20 μm bore needles showed no difference in survival from controls. However, 25 μm implants with 50 μm bore sizes, and 50 μm implants with 100 μm bore sizes both showed a reduction in viability post injection in zebrafish compared to tricaine controls. Based on these preliminary results, zebrafish embryos tolerate implants ranging from 10 – 25 μm in diameter, while 50 μm was deemed too large for the embryo. Further refinement of techniques is anticipated to improve success and retention rates.
Histology techniques were developed for use with 3 – 5 mm zebrafish larvae. By embedding tissues in an agar array and reducing fixation times to 2 hours, improvements were observed in tissue cohesion. Additionally, the agar matrix provides a well-organized structure, which lends itself to improved efficiency for future work.

abstract: M.A.Sc.


title: A Continuum Modelling Study of Macro-Geometry choices and Their Impact on Excavation Damage Zone Development in Brittle Rock at Depth

subject:
Tunnelling
Numerical Modelling
Brittle Rockmass
Excavation Damage Zone
Deep Geological Repository

abstract:
Canadian and International experts agree that deep underground repositories are the single best solution regarding safe, long-term nuclear waste disposal (IAEA 2009). Numerous European and Asian countries have already begun extensive research and preliminary design analyses associated with site assessment for high-level fuel storage facilities known collectively as deep geological repositories (DGRs) (ANDRA 2005, Armand et al. 2003, NAGRA 2002, Martino and Chandler 2004). In Canada, Kincardine, ON, is currently the proposed site that will host the low- to medium-level nuclear waste generated from the Bruce, Pickering and Darlington nuclear power plants. The project conceptualization, as well as the specific sites, have undergone extensive public critique and analyses. The project is in the final licensing stage of the process.
To ensure long term stability and safety of the DGRs, the prediction and understanding of the excavation damage zone (EDZ) around the associated shafts, placement room tunnels, storage voids and access tunnels is paramount. The general EDZ consists of component zones of damaged, fractured and influenced rock moving radially away from the center of the excavation. The outer “influenced” zone consists of rock that has been elastically strained, while the “damaged” zone undergoes small scale, discontinuous crack damage, subsequently increasing the permeability of the surrounding rockmass. The “fractured” zone is located nearest to the excavation wall/face, where continuous (connected) fractures dominate.
Numerous details within a preliminary design of the tunnels and intersections within a DGR will influence the development and ultimate impact of the EDZ on ultra-long-term repository safety. For the various DGR tunnelling projects that include the placement room tunnels, access tunnels and vertical shafts, details of shape will dictate the ultimate support demands and safety requirements. Using case examples, as well as 2-dimensional and 3-dimensional continuum numerical modelling simulations, this thesis will illustrate key impacts of macro-geometry choices, such as shape and dimensions of placement room and access tunnels, as well as details, which include corner geometry, aspect ratio, excavation sequence and methodology, on EDZ and highly damaged zone (HDZ) development in underground infrastructure.

abstract: M.A.Sc.


title: Characterization of Rockmass Properties and Excavation Damage Zone (EDZ) Using A Synthetic Rock Mass (SRM) Approach

subject: Synthetic Rock Mass (SRM)

subject: Characterization of Strength and Deformability of Jointed Rockmasses

subject: Coupled Hydro-Mechanical Processes

subject: Excavation Damage Zone (EDZ) Development around Tunnels

subject: Discrete Fracture Network (DFN)-Discrete Element Method (DEM) Approach

subject: Brittle Fracturing of Low-Porosity Rock

subject: Scale-Dependency of Mechanical Properties of Jointed Rockmasses

subject: Representative Elementary Volume (REV)

abstract:
A detailed understanding of strength and fracturing behaviour of the rockmass is essential for coherent design of underground structures such as deep geological repositories (DGRs) for long-term nuclear waste storage. The development of advanced numerical approaches, such as Synthetic Rock Mass (SRM), provides an effective tool to simulate the failure process of the rock at various scales from laboratory scale samples to excavation scale problems. As an alternative to empirical methods and physical testing, the SRM technique can also be employed to estimate the deformability and strength properties of jointed rockmasses under a wide range of scales and boundary conditions.

In this study, a two-dimensional code based on the discrete element synthetic rock mass model is used to simulate the behaviour of low-porosity rocks under hydro-mechanical loading. A methodology is developed to calibrate the SRM models to the response of laboratory-scale intact rock. Using numerical simulation, the role of connectivity of induced micro-cracks on increasing the permeability of a laboratory-tested sample is investigated. The capability of the model to simulate the effect of pore fluid pressure on weakening the strength of the rock is examined. Next, the calibrated model is applied to simulate the formation of the excavation damage zone (EDZ) around unlined underground tunnels in crystalline granitic and laminated sedimentary rocks. The understanding gained from simulating damage development around case history tunnels leads to recommendations for calibrating the micro-parameters of the model for tunnel-scale applications.

In addition, an SRM model coupling the discrete fracture network (DFN) model and discrete element grain-based model (GBM) is used to characterize the strength and deformability of highly interlocked jointed rockmasses under confined and unconfined conditions. The scale dependency and variability of the rockmass properties are investigated using the concept of Representative Element Volume (REV). The results of numerical modelling are then compared with the predicted values obtained from empirical methods.

It is demonstrated that the SRM technique can be successfully applied to simulate the observed shape and extent of the damage zone around underground excavations. The estimated strength based on the SRM modelling results is in agreement with the unconfined strength predicted by the empirical Hoek-Brown criterion.

abstract: PhD


title: Genetic Structure and Connectivity of the Endangered Butler's Gartersnake (Thamnophis butleri) Across the Fragmented Landscape of Southwestern Ontario

contributor:
Lougheed, Stephen C.
Biology

subject:
Population Genetics
Landscape Genetics
Ontario
Conservation Genetics
Garternsnake
Thamnophis butleri
Thamnophis sirtalis

abstract:
Genetic patterns in many species are affected by environmental features that may enable or obstruct gene flow. Geographical isolation of conspecific individuals by uninhabitable expanses can lead to genetic separation. For species impacted by human activities, understanding how they interact with their environment can promote re-establishment of population connectivity and conservation. Thamnophis butleri (Butler’s gartersnake) is an Endangered species in Ontario, its range comprising three disjunct regional populations: Essex County, Lambton County, and Luther Marsh. Thamnophis butleri is a specialist of wetland-adjacent grassland-type habitat, thus its distribution is constrained by Southwestern Ontario’s largely agricultural landscape. Genetic differentiation among populations inhabiting these isolated regions was shown in a single previous study. I explored genetic structure more comprehensively, augmenting the geographic sampling and deploying landscape genetics approaches.
In my first data chapter, I tested for population differentiation in both T. butleri and the generalist Thamnophis sirtalis sirtalis (eastern gartersnake) where the congeners occur sympatrically in Ontario. Assignment analyses revealed clear genetic structure within T. butleri, with clusters corresponding to geographical regions: one each in Lambton and Luther Marsh, and two in Essex, one along the shoreline and another in LaSalle, ON and the Ojibway Prairie Complex. Dispersal by river, either aquatically or along riparian corridors, may facilitate connection in the Lambton and Essex shoreline clusters, while the Ojibway/LaSalle cluster may have no need to disperse (occurring in good-quality habitat) or be impeded from dispersing by intervening urban areas. In contrast, I found that T. s. sirtalis comprises a single genetic population, implying that its generalist ecology allows for dispersal through this heavily altered landscape.
In my second data chapter, I explored the relationship between patterns of T. butleri genetic differentiation and landscape composition across its Canadian range, using Mantel-based methods to test the correlation along either uniform or habitat-delineated distance matrices. The relationship between landscape and genetics varied among regional populations, from resistance-based in Lambton to distance-based in Essex. Treating open water as a potential impediment or facilitator of dispersal did not alter my conclusions, raising the possibility of aquatic dispersal that may occur at a different spatial scale than terrestrial dispersal.

abstract: M.Sc.


title: An Experimental Gel-Based Treatment of Iron Gall Ink Corrosion Halos: Sodium Metabisulfite and Diethylene Triamine Pentaacetic Acid Solution in Agarose Gel

contributor:
Murray, Alison
Hill, Rosaleen
Art Conservation

subject:
Iron gall ink
Sodium Metabisulfite
Corrosion Halos
Diethylene Triamine Pentaacetic Acid
Gel-Based Treatment
Agarose Gel
Paper Conservation

abstract:
A research project was carried out at Queen’s University to determine the effectiveness of an agarose gel-based treatment of iron gall ink corrosion halos using reducing agent sodium metabisulfite and chelating agent diethylene triamine pentaacetic acid. The ink fabricated for this experiment contained the metal ions of iron, copper, and zinc to increase the amount of visible corrosion, as well as replicate historic inks that have metals other than iron in them. The experimental treatment accounts for the chelation of the copper and zinc ions from the paper substrate along with iron, which cannot currently be done using the widely accepted calcium phytate treatment, as phytate is iron selective.
The effectiveness of this experimental treatment was primarily determined using qualitative methods of analysis. Photographic documentation, ultraviolet fluorescence, and optical microscopy showed visual effects of the treatment from color change in the ink, to a reduction in corrosion-induced fluorescence, and ink bleeds where the cyclododecane fixative failed. Scanning election microscopy-energy dispersive X-ray spectroscopy and electron probe microanalysis were the techniques that made clear the distribution of elements in the ink and from the treatment on the paper samples. However, the concentrations of metals in the substrate were too low to detect evidence of corrosion halos via these analytical methods. Color spectrophotometry and pH measurements of the sample swatches yielded results that support observations made with the aforementioned techniques and determined the treatment safe for the paper substrate, respectively. Unfortunately, inductively coupled plasma atomic emission spectroscopy, the main technique that could have confirmed the success of the treatment, did not yield results because of unknown error. Though no definite conclusions could be drawn on the effectiveness of the treatment, suggestions for future research and potential treatment procedures can be considered based on the results from the qualitative analyses.

abstract: M.A.C.


title: Towards Provably Correct Services: Automated Service Composition Via Supervisory Control Synthesis

contributor:
Juergen, Dingel
Karen, Rudie
Computing

rights: Attribution-NonCommercial 3.0 United States

subject:
Service Composition
Automatic Service Composition,
Supervisory Control Theory
Controller Synthesis
Web Services
Discrete Event Systems
Labelled Transition Systems
Service Oriented Computing
Automata
Service Oriented Architecture (SOA)
Software Engineering
Correct-by-Construction

abstract:
Service-oriented computing (SOC) is a distributed computing paradigm that is revolutionizing the development of software systems. Service-oriented architecture (SOA) provides a framework  for realizing and implementing SOC.  A Web service is a key concept for developing SOA applications that allows interoperability among distributed software applications deployed on different platforms and architectures, which is important for many electronic business applications. Web services enable organizations to carry out certain business activities automatically and in a distributed fashion.

However, in some circumstances, a single service is not able to perform a certain task and it becomes necessary to compose two or more services in order to complete it. Thus, a key research challenge in SOA is the problem of automated service composition. Several approaches exist that tackle the problem of automatic service composition; however, the task of generating provably correct Web service compositions still remains a challenging and complex task. The goal of this dissertation is to leverage the existing work on supervisory control to solve the problem of automated service composition with a focus on control and correctness.

Therefore, in this dissertation, we develop a novel formal framework for modeling Web service compositions based on Supervisory Control Theory (SCT) of discrete-event systems. We model services that exchange messages and exhibit nondeterministic (runtime-dependent) behaviours based on runtime input. The objective  is to synthesize a supervisor that interacts with a given set of Web services through messages to guarantee that a given specification is satisfied. The framework employs Labelled Transition Systems (LTSs) equipped with guards and data variables to model Web services and provides a technique to synthesize a controller. We model the interactions of services asynchronously and we use the guards and data variables to express certain preconditions which are then propagated from the system requirements through the overall composite service.
The dissertation also provides a prototype implementation toolkit and an evaluation of the applicability of the approach using a number of case studies.

A key novelty of this work is the application of control theory to service-oriented computing and the incorporation of runtime input into the supervisor generation process.

abstract: PhD


title: Law Enforcement Attitudes of Current Public and Departmental Surveillance Technologies: A Qualitative Case Study of The Toronto Police Service

contributor:
Sytsma, Victoria
Sociology

subject:
Police Body-Worn Cameras
Police Legitimacy
Procedural Justice
Visibility
Toronto Police Service
Accountability
Transparency
Surveillance theories
Panopticon
Synopticon
Police and Community Relationship

abstract: This thesis explores the perceptions of front-line police officers surrounding synoptic and panoptic surveillance and the implications of police body-worn cameras on community relations, citizen’s recording devices and police practice. The study involves a qualitative approach that utilized one-on-one, semi-structured interviews, in which participants were those members of the Toronto Police Service who wore body-worn cameras during an earlier pilot study of the device conducted by the Toronto Police Service. Police as a sampling group are very exclusive and hard to gain access to, as such this study relied on a snowball sampling strategy which resulted in a sample size of 7. While sample size is a major limitation of this study, these 7 interviews provided rich data that were able to provide a valuable and humanizing dialogue of police officers. Transcriptions of interviews were collected and thematically analyzed, resulting in commonalities among participant responses. These commonalities suggest that officers involved in the piloting project that were interviewed share similar perceptions and concerns of this new technology, whether it be positive or negative. Themes that were established include: Context; Synoptic Surveillance; Accountability; Police and Community Relationship and Trust; Impact on Officer’s Job, Career and Routine; Officer Repercussions & Protection from Accusations; Officer Change in Behaviour Due to Surveillance Devices; Officer Physical Safety; Citizens Behavioural Changes and Reactions Body-Worn Cameras; Social Media; Privacy Concerns; Officers Favourability toward Wearing Body-Worn Cameras; and the Overall Impact Body-Worn Cameras have on Policing. Participants reported while this surveillance tool is beneficial in theory, in practice the implications of this device are increasingly negative on police practice and community relations. Study results are framed using contemporary theories of surveillance and concepts central to police legitimacy, and for the purpose of this research the culmination of these notions has been termed the Surveillance Accountability Framework. The concerns surrounding police body-worn cameras raised by this research should be considered for further research and improvement, particularly due to the increasing amount of police services planning on adopting this new technology.

abstract: M.A.


title: Performing Above One’s Position: Micro-Institutional Licenses on Physicians and Healthcare Managers During an Outbreak

contributor:
Dacin, Tina
Business

subject:
Organizational Behaviour
Organizational Theory
Management
Hierarchy
Organizational Ceremonies
Healthcare Sector

abstract: Seeking flexible structures, many organizations today are abandoning the ceremonies of hierarchy. The idea is that removing traditional dress codes, segregated workspaces, and formality with superiors will de-emphasize status distinctions and encourage members of different rank to collaborate freely. On the other hand, researchers show that hierarchies of are often resilient because they are reinforced by external institutions, such as professional regulations and industry norms. This dissertation explores the conditions under which ceremonial change enables flexible use of authority in large, institutionalized organizations. I report on an inductive study of four Toronto hospitals in which scripted experiences of the medical hierarchy were undermined during efforts to contain a disruptive outbreak. I find that ceremonial changes weakened organizational members’ commitment to existing hierarchies, sometimes helping junior members bring their expertise to settings usually reserved for senior members, but at other times leading to tensions and difficulty coordinating expertise. Based on these findings, I propose that institutionalized organizations can encourage flexible use of authority in a two-step process in which ceremonies emphasizing status distinctions are first replaced then senior members build consensus around new rules, norms, and beliefs that coordinate expertise.

abstract: PhD


title: Public Project, Private Developer: Understanding the Impact of Local Policy Frameworks on the Public-Private Housing Redevelopment of Regent Park in Toronto, Ontario

contributor:
Donald, Betsy
Létourneau, Marcus
Geography and Planning

subject:
Public-Private Partnerships
Public Housing
Public Policy
Social Mix
Real Estate Development
Revitalization
Urban Planning
Urban Policy
Redevelopment
Regent Park
Toronto
Ontario
Community Housing
Social Housing

abstract: This thesis examines Regent Park, a public housing community in Toronto, Ontario undergoing mixed-income revitalization through a public-private partnership (3P) since 2006. Much of the existing literature has studied the Regent Park revitalization from the perspective of public housing tenants, conceptualizing the project as a continuation of redevelopment efforts in the United States. However, this approach neglects the unique Canadian policy context and the point-of-view of industry professionals involved in the development process. Using Toronto as the primary lens of geographic analysis to study the revitalization, a qualitative, mixed-methods approach was employed in this thesis to focus on the local policy context and perspective of individuals involved in the Regent Park redevelopment process. Data was gathered, primarily, through interviews with 25 public and private sector professionals. Subsequent analysis generated several findings and recommendations for application at Regent Park and 3P redevelopment efforts in Toronto and other cities. Where many recent studies depict the Regent Park revitalization as having an overall negative outcome for public housing tenants and other public shareholders, this thesis, in contrast, found that the project is delivering notable social benefits to Regent Park and surrounding communities, while avoiding the displacement of low-income residents characteristic of public housing redevelopment in the US. Western governments have increasingly partnered with the private sector to deliver services and infrastructure over the last 30 years. It is therefore imperative to explore a diversity of perspectives to improve the outcomes of 3P social service delivery in the future, as this thesis does by understanding the viewpoints of development industry professionals in Toronto.

abstract: M.A.


title: Analysis of Clay Minerals in the Mudflats of Sulfate-Rich Saline Lakes

subject:
Saline Lakes
Mg-smectite
Diatom
Saskatchewan
Bolivia
Authigenic
Realgar
Arsenic
Salar
Mudflat
Phyllosilicate

abstract:
Clay minerals are important targets for interpreting past environments due to their ubiquity on the surface of terrestrial planets, sensitivity to the prevailing geochemical conditions, and ability to preserve biosignatures. Modern saline lakes that develop sulfate-rich brines are less extensively analyzed due to their relative scarcity compared to those that develop bicarbonate-rich brines. Moreover, most modern sulfate-rich systems are small in area (<100 km2), playa dominated, and rich in detritus making them difficult to sample and to study. Yet, the number and diversity of these lakes makes them important for understanding authigenic mineral formation. The goal of this study was to evaluate authigenic and detrital minerals in the mudflats of sulfate-rich saline lakes.
This research focused on microscale (cm) investigations of the mudflats from 23 lakes from the Great Plains of southern Saskatchewan, Canada, and Andean Plateau, Bolivia for a total of 407 sediment samples. For detrital-rich sediments, authigenic illite was consistently found within sand lenses of the mudflats, was rich in Al, Mg, and Fe, and displayed lath-like morphologies. Uncommon minerals were also found containing elements usually in minor/trace quantities that concentrate in the closed-basins. In Laguna Chiar Khota, Bolivia for example, the arsenic-rich minerals realgar and hörnesite were found within the mudflats. Lastly, this thesis demonstrates that the biologically-mediated uptake of silica by diatoms can shift the geochemical parameters within the lakes, where Mg-smectite form instead of sepiolite in an otherwise silica-rich environment.
Overall, this research contributes to our understanding of authigenic clay formation recognizing similarities between these highly diverse environments. In detrital-rich environments where authigenic minerals are difficult to identify, such as the deltaic-lacustrine deposits in Gale crater, Mars, this study shows that authigenic illite can be found within the sand-lenses of the mudflats. Moreover, this study also shows that we need to consider the factors of diatom dissolution with respect to dissolved silica. The influence of diatoms on the phyllosilicates in brackish lakes suggests we may need to examine the modes of formation for sepiolite in ancient deposits, which may be forming from post depositional alteration of the lacustrine sediments.

abstract: PhD


title: Optimization of Sintering Conditions for Cerium-doped Yttrium Aluminum Garnet

contributor:
Krstic, Vladimir
Mechanical and Materials Engineering

subject:
YAG
Phosphor
Sintering Conditions
Optimization
Ce

abstract: YAG:Ce phosphors have become widely used as blue/yellow light converters in camera projectors, white light emitting diodes (WLEDs) and general lighting applications. Many studies have been published on the production, characterization, and analysis of this optical ceramic but few have been done on determining optimal synthesis conditions. In this work, YAG:Ce phosphors were synthesized through solid state mixing and sintering. The synthesized powders and the highest quality commercially available powders were pressed and sintered to high densities and their photoluminescence (PL) intensity measured. The optimization process involved the sintering temperature, sintering time, annealing temperature and the level of Ce concentration. In addition to the PL intensity, samples were also characterized using particle size analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The PL data was compared with data produced from a YAG:Ce phosphor sample provided by Christie Digital. The peak intensities of the samples were converted to a relative percentage of this industry product. The highest value for the intensity of the commercial powder was measured for a Ce concentration of 0.3 mole% with a sintering temperature of 1540°C and a sintering dwell time of 7 hours. The optimal processing parameters for the in-house synthesized powder were slightly different from those of commercial powders. The optimal Ce concentration was 0.4 mole% Ce, sintering temperature was 1560°C and sintering dwell time was 10 hours. These optimal conditions produced a relative intensity of 94.20% and 95.28% for the in-house and commercial powders respectively. Polishing of these samples resulted in an increase of ~5% in the PL intensity.

abstract: M.A.Sc.


title: Queering the Rural in Contemporary Argentine Cinema: Taekwondo, Esteros, and Como Una Novia Sin sexo

contributor:
Mennell, D. Jan
Cultural Studies

subject:
Queer Rural Studies
Argentine Cinema
Queer Cinema
Scopophilia
Haptic Visuality
Homosociality

abstract: In queer social histories, the city has been privileged as a normative space for queer identity and social progress to be actualized. Compared with urban spaces, rural spaces continue to be perceived as always dangerous and antagonistic for people who identify as queer. In cinema with queer images, this narrative of the rural as hostile is being challenged by films with queer images that contain positive narratives within a rural or non-urban milieu. In other words, these films are presenting counter-narratives to what scholar Jack Halberstam has called metronormativity. Under a metronormative optic, it is assumed that queer people in a rural space will adopt the spatial narrative of movement from that rural space to an urban space. In 2016, three Argentine films were released that challenged metronormative assumptions: Marco Berger and Martín Farina’s Taekwondo, Papu Curotto’s Esteros, and Lucas Santa Ana’s Como una novia sin sexo / Bromance. Through the representation of queer desire in rural spaces, these films offer a counter-narrative to the privileging of the urban in queer sociality. Through close readings of these three films that take into consideration sexual fluidity, bodily experience, and their intersections with natural elements and iconography, it is evident that there is a contemporary impulse to cinematically convey queer rurality, an understudied and overlooked phenomenon.

abstract: M.A.


title: Constructing Magnificence and Its Discontents: Analysis of the Series Magnificent Century (Muhtesem Yuzyil)

contributor:
Tolmie, Jane
Naaman, Dorit
Cultural Studies

subject:
Memory
Nostalgia
Melancholy
Phenomenology
Affect
Turkey
Popular Culture
Postfeminism
Neoliberalism
Television

abstract: In this thesis, I primarily investigate the phenomenological implications of the television series Magnificent Century. Following phenomenology’s objective of assessing the essential meaning structures of our embodied experiences, I chart the major contours of the series’ socio-cultural resonances for our contemporaneous context of living. I first suggest that Magnificent Century’s worldwide popularity relies on its central character Hurrem’s alignment with postfeminist sensibilities of our age. Then, I set out to demonstrate that gendered power reversals as well as gender role reversals constitute the series’ main affective magnets. Third, I investigate the co-constructive relationship between masculinity and nationhood in the way it is built upon the combined denigration of femininity, foreignness, and peripheral masculinities. A major point of emphasis is to locate and reflect on the series’ performances of various forms of neoliberal imaginaries and affectivities. In the last two chapters of the thesis, my attention turns to Magnificent Century’s specific cultural work on Turkey’s memoryscape. I analyze the socio-cultural functioning of myths of innocence and originary identity for the Turkish populace. A central concern for me is to investigate the series’ simultaneous celebrations and denunciations of imperial nostalgia. I closely analyze the cultural politics of melancholia and nostalgia in Turkey through its imprints in the series. I conclude the thesis through an investigation of one of the greatest media events of recent years in Turkey, the execution of Prince Mustafa, with an objective to understand the socio-cultural reasons that lie beneath unparalleled degrees of public reaction to young prince’s televised murder.

abstract: PhD


title: Microbial Modulation of Nociception

contributor:
Lomax, Alan
Neuroscience Studies

subject:
Microbiota
Sensory Neurons
Nociception
Visceral Pain
Gastrointestinal

abstract: Peripheral pain signaling reflects a balance of pro and anti-nociceptive influences; the contribution by the gastrointestinal (GI) microbiota to this balance has received little attention. GI disorders such as inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) are associated with exaggerated visceral nociceptive actions that may involve altered microbial signaling, particularly given the evidence for bacterial dysbiosis in these conditions.  Despite ongoing research, the cellular mechanisms underpinning bacterial modulation of visceral pain remain incompletely understood.  Accordingly, we tested whether a community of commensal GI bacteria derived from a healthy human donor (microbial ecosystem therapeutics; MET-1) could alter the excitability of small dorsal root ganglion (DRG) neurons from mice. Additionally, we tested whether perturbation of the healthy GI microbiota in vivo by antibiotic administration could also alter neuronal excitability in mice.  Furthermore, we examined whether nociceptive signaling in a humanized IBS mouse model could be modulated by a diet low in fermentable carbohydrates, an intervention known to alter GI microbiota and improve overall symptoms of IBS patients. Exposure of DRG neurons to supernatant from MET-1 reduced their excitability by significantly increasing rheobase by 32% compared to controls (p=0.0003). The effect of MET-1 was mediated in part by serine proteases through activation of protease-activated receptor (PAR)-4. Perturbation of gut microbiota in vivo by administration of non-absorbable antibiotics increased thermal somatic pain responses by 16% (p=0.008) and increased the excitability of DRG neurons by decreasing rheobase by 22% (p=0.0039) compared to controls. The increase in excitability of DRG neurons was reversible, independent of immune activation and not restricted to DRG neurons that innervate the gut. Supernatant from the colonic mucosa of mice colonized with the microbiota of IBS patients and fed a diet high in fermentable carbohydrates increased the excitability of DRG neurons by decreasing rheobase up to 24% compared to mice fed a diet low in fermentable carbohydrates (p=0.0002). The increase in excitability of DRG neurons appeared to be due to histamine and proteases. Together, these results indicate that pain signaling can be modulated by microbiota-neuronal interactions. Therefore, therapies that induce or correct microbial dysbiosis may affect visceral pain.

abstract: PhD


title: The Ideal Immigrant: Deconstructing Immigrant Success Stories in Ontario Immigrant Settlement Agencies

contributor:
Levine-Rasky, Cynthia
Sociology

subject:
Immigrant Settlement Support
Neoliberal Governmentality
Canadian Racialization
Racialization of Immigrants

abstract: A common narrative of “successful” immigrants often depicts individuals who are hard working, resilient in adverse situations, and have a positive can-do attitude. Such characterization of newcomers attributes immigrant success to individualistic qualities and ultimately fails to acknowledge systemic barriers that immigrants encounter in their efforts to settle and integrate in Canada. Using immigrant success stories published by immigrant settlement service provider organizations (SPOs) in Ontario, this study is informed by Foucault’s concepts and other theories of race and racialization as a framework to examine the discourses and practices mobilized within immigrant settlement sector. Neo-liberalism is analyzed from the perspective of governmentality as a multitude of rationalities, practices, and techniques linked to governing mechanisms that (re)produce responsibilized citizen-subjects. I examine the ways in which the shift towards a more unstable and competitive funding regime since the 1990s have resulted in the marketization and de-politicization of settlement support for newcomers. Inscription devices are thus essential neo-liberal techniques through which the state funders can govern the settlement service agencies and their clients “at a distance.” Furthermore, I discuss a “triangulated” racial framework and various citizen and non-citizen subjects to consider the racializing effects of constructing a figure of an ideal immigrant. I argue that the stories suggest ideal immigrants are enterprising subjects who make “rational” and “reasonable” choices to think and behave in particular ways. Structural barriers that immigrants encounter in their efforts to settle in Canada are thus de-politicized as personal issues and immigrants are responsibilized for their own settlement and integration. I particularly problematize “Canadian experience” as a discourse to deconstruct the racializing effects for immigrants who are de-skilled and forced to participate in precarious and unpaid work. The findings of this study suggest that, within neo-liberal governmentality, particular practices, techniques, and discourses are mobilized by state funders and settlement service providers to reproduce certain subjectivities and realities for new immigrants in Canada that ultimately have racializing, responsibilizing, de-politicizing effects.

abstract: M.A.


title: Large-Eddy and Wall-Modeled Simulations of Turbulent Flow Over Two-dimensional River Dunes

contributor:
Piomelli, Ugo
Mechanical and Materials Engineering

subject:
Hybrid RANS/LES
Two-Dimensional Dunes
Wall-Modeling
DES

abstract:
The Large-Eddy Simulation (LES) technique is only applicable to wall-bounded flows at moderate Reynolds numbers due to its computational cost. Wall-layer models are designed to extend the LES concept to engineering flows at high Reynolds numbers by bypassing the near-wall region and modeling its effects on the outer flow.

In this work, large-eddy and hybrid Reynolds-Averaged Navier-Stokes (RANS)/LES calculations are performed for turbulent flow over a two-dimensional dune geometry. A Lagrangian dynamic eddy-viscosity model is applied for resolved LES computations. Also, Wall-Modeled LES (WMLES) calculations are performed using models of the Detached-Eddy Simulation (DES) family based on Spalart & Allmaras (1992) turbulence model, including DES, Delayed DES (DDES), and Improved DDES (IDDES). Simulations are carried out at two different Reynolds numbers, Re_b = 18 900 and 50 000, based on bulk velocity and average dune height. Wall-resolved LES calculations are used to investigate the accuracy of the present wall-layers.

Compared to attached, equilibrium flows or flows with a mild separation, a higher accuracy was achieved in prediction of the mean and second order statistics using all the present hybrid methods. Large, three-dimensional eddies are generated due to the instability of the shear layer after flow separation at the dune crest. As they convect downstream with the mean flow, these eddies interact with the near-wall flow and act as a mechanism to increase the eddy-generation at the RANS/LES interface. As a result, the interface between the RANS and LES regions moves toward the bed and leads to a more realistic turbulence cycle in the RANS region.

Considering both the first and second order statistics, as well as the flow physics included in the instantaneous turbulent field of the simulation, the IDDES model resulted in a higher level of accuracy compared to the DES and DDES methods at all the tested Reynolds numbers. However, the same grid density as the two other models might lead to noise propagations over the reattachment region. To resolve this issue it might be necessary to refine the mesh in wall-parallel directions (streamwise and spanwise directions) when using IDDES as the wall-layer model.

abstract: M.A.Sc.


title: Theorizing Mass Incarceration: Analyzing Aboriginal Over-Representation in Light of Section 718.2(e) of the Canadian Criminal Code

contributor:
Beamish, Rob
Sociology

subject: Aboriginal Incarceration Over-representation

abstract:
This study assesses the impact of changes in Bill C-41 on Aboriginal offenders in Canada. Passed in September 1996, Bill C-41 amended the Criminal Code seeking to clarify sentencing principles. Section 718.2(e) instructs judges to use incarceration only as a last resort when appropriate. Although it indicates that Aboriginal offenders must be given special consideration, it does not provide specific conditions or parameters for its use, leaving it to the judges’ discretion. In 1999 some clarification was provided in the Supreme Court of Canada decision of R. v. Gladue. Gladue clarified the application of section 718.2(e) and highlighted its role in alleviating Aboriginal overrepresentation in prisons.
This thesis considers the disproportionate incarceration levels of Aboriginal offenders in Canada and the effectiveness of 718.2(e) in ameliorating the problem. It examines judiciary reasoning for the application of section 718.2(e) in 21 published Court of Appeal cases. The study employs a constructivist, grounded theory approach to discourse analysis of extant case documents. Quantitative data are also used to identify trends in offenders’ backgrounds.
Findings reveal that most cases involved male offenders between the ages of 18 and 34 with varying educational backgrounds. In most cases the offender pleaded guilty during the sentencing trial, had a prior record, and had made rehabilitative efforts post-sentencing. The overwhelming majority of offenders had experienced unfavourable upbringings and circumstances in their lives and abused alcohol and/or drugs. Analysis of judges’ sentencing and decision making process revealed five predominant themes: Protection of public rhetoric, Denunciation and Deterrence, Rehabilitation, Special Cases, and Considerations of Gladue. The majority of appeal cases were dismissed or maintained carceral outcomes.

abstract: M.A.


title: Surface Water Classification and Monitoring using Polarimetric Synthetic Aperture Radar

contributor: Geological Sciences and Geological Engineering

subject:
Synthetic Aperture Radar
Remote Sensing
Flood Hazards
Surface Water
PolSAR

abstract: Surface water classification using synthetic aperture radar (SAR) is an established practice for monitoring flood hazards due to the high temporal and spatial resolution it provides. Surface water change is a dynamic process that varies both spatially and temporally, and can occur on various scales resulting in significant impacts on affected areas. Small-scale flooding hazards, caused by beaver dam failure, is an example of surface water change, which can impact nearby infrastructure and ecosystems. Assessing these hazards is essential to transportation and infrastructure maintenance. With current satellite missions operating in multiple polarizations, spatio-temporal resolutions, and frequencies, a comprehensive comparison between SAR products for surface water monitoring is necessary. In this thesis, surface water extent models derived from high resolution single-polarization TerraSAR-X (TSX) data, medium resolution dual-polarization TSX data and low resolution quad-polarization RADARSAT-2 (RS-2) data are compared. There exists a compromise between acquiring SAR data with a high resolution or high information content. Multi-polarization data provides additional phase and intensity information, which makes it possible to better classify areas of flooded vegetation and wetlands. These locations are often where fluctuations in surface water occur and are essential for understanding dynamic underlying processes. However, often multi-polarized data is acquired at a low resolution, which cannot image these zones effectively. High spatial resolution, single-polarization TSX data provides the best model of open water. However, these single-polarization observations have limited information content and are affected by shadow and layover errors. This often hinders the classification of other land cover types. The dual-polarization TSX data allows for the classification of flooded vegetation, but classification is less accurate compared to the quad-polarization RS-2 data. The RS-2 data allows for the discrimination of open water, marshes/fields and forested areas. However, the RS-2 data is less applicable to small scale surface water monitoring (e.g. beaver dam failure), due to its low spatial resolution. By understanding the strengths and weaknesses of available SAR technology, an appropriate product can be chosen for a specific target application involving surface water change. This research benefits the eventual development of a space-based monitoring strategy over longer periods.

abstract: M.A.Sc.


title: Modelling and Development of Droplet Generation Method for Magnetically Actuated Digital Microfluidics

contributor:
Oleschuk, Richard
Chemistry

subject:
Microfluidics
Fluid Dynamics
Analytical Chemistry
Superhydrophboic
Surface Tension

abstract: Digital microfluidics is useful in miniaturizing different types of biological tests due to an ability to perform multiple operations on a single chip with a single common geometry. However, one of the largest problems in using digital microfluidics has been biofouling during these processes, a phenomenon which is exacerbated when using electric fields for fluid manipulation. Magnetic microfluidics is an alternative actuation mechanism, which does not have this same limitation. However, until recently it has been impossible to create drops, which can also be subsequently moved to perform multiple step analyses. In this thesis, a method for creating drops on superhydrophobic surfaces using magnetic force as the primary actuation mechanism is outlined. Using numerical simulations in Comsol Multiphysics, the method was explored to determine several of the limitations of the system, including the minimum actuatable volume (5 μL). Additionally, the flow within the drops was explored to obtain a better understanding of the experimental results. Experimental validation of the results followed, and it was found that the system showed a 1-to-1 linear change in drop volume relative to expected dispensed volume, verifying the theoretical model. Experimental validation found that the error of the system is constant over any dispensed volume at ±0.5 μL. The method was applied to miniaturize a standard test for hard water determination, a complexometric EDTA titration. The results from a specially designed chip are compared to a titration of a 10 mL volume of the same sample and two were found to be equal within error (100-170 ppm for the chip, 124±2 ppm for the standard method). The water hardness estimate from the chip was further improved upon by image analysis, and the range narrowed to 120±15 ppm, again within the same error as the standard method. Together with the theoretical analysis, this result verifies the practicality of the method for analytical operations. Finally, preliminary work into making the magnetic droplet manipulation method more general was conducted, and it was found to be possible to create chips which utilize any combination of droplet mixing, merging, moving, and splitting.

abstract: M.Sc.


title: Characterization of arsenic-hosting solid phases in Giant mine tailings and tailings dust

subject: Arsenic Dust Geochemistry Tailings Synchrotron Mineralogy

abstract: Dust from the tailings at Giant mine, an abandoned mine in northern Canada, has been a concern among local residents, particularly those from Ndilo, a community of Yellowknives Dene First Nations located approximately 2.5km southeast of the site. The arsenic-bearing tailings at Giant mine are left vulnerable to high velocity winds after snow melt in the late spring, when it is too cold to apply a dust suppressant to the tailings. The main objective of this research is to characterize the fine fraction of the tailings (particles <63µm in diameter) and dust that could be inhaled or ingested from Giant mine to identify the As-hosting solid phases therein. Surface tailings material was sampled from three of the tailings impoundments on site, and sieved to <63µm. From May to July of 2016, a total suspended particulate (TSP) high volume air sampler was set up to continuously sample airborne material coming from the tailings. Bulk chemical data was determined via inductively coupled plasma-optical emission spectrometry (ICP-OES) and -mass spectrometry (ICP-MS); mineralogical data via scanning electron microscope (SEM)-based automated mineralogy, electron microprobe analysis (EMPA), and synchrotron-based micro X-ray diffraction (µXRD), micro X-ray fluorescence (µXRF); and oxidation state data for As via X-ray absorption near edge structure (XANES). Bulk chemical data show elevated concentrations of As, Sb, Zn, Pb, Cu, and Ni. The As in the tailings is a mix of As(I-), As(V), and As(III), and is more concentrated in the <63µm fraction (3000 – 9300 ppm As) than in the unsieved tailings. Roaster-generated Fe-oxides (maghemite), Ca-Fe arsenate, and arsenopyrite comprise the majority of As-bearing particles in the surface tailings; Ca-Fe arsenate poses the greatest risk to human health of these three as it is the most bioaccessible. Fe-oxides were the only As-host found in the dust. Very little arsenic trioxide was found in the tailings, and no arsenic trioxide was found in the dust samples. However, previous studies have shown that the soils near the Giant mine tailings do contain arsenic trioxide from historic stack emissions, indicating that these soils might actually present a higher risk than the tailings themselves.

abstract: M.Sc.


title: Stress Estimation From Borehole Scans For Prediction Of Excavation Overbreak In Brittle Rock

subject:
Geology
Rock Mechanics
Engineering
Geotechnical Engineering
Geomechanics
Stress
Borehole Breakout
Mining

abstract:
In the field of geomechanics, one of the most important considerations during design is the state of stress that exists at the location of a project. Despite this, stress is often the most poorly understood site characteristic, given the current challenges in accurately measuring it. This stems from the fact that stress can’t be directly measured, but must be inferred by disturbing the rockmass and recording its response. Although some methods do exist for the prediction of in situ stress, this only provides a point estimate and is often plagued with uncertain results and practical limitations in the field. This research proposes a methodology of continuously predicting stress along a borehole through the back analysis of borehole breakout and how this same approach could be employed to predict excavation overbreak.
	KGHM’s Victoria Project in Sudbury, Canada, was the location of data collection, which firstly involved site characterization through common geotechnical core logging procedures and laboratory scale intact core testing. Testing comprised Brazilian tensile strength and unconfined compressive strength testing, which involved the characterization of crack accumulation in both cases.
	From two pilot holes, acoustic televiewer surveys were completed to characterize the occurrence and geometry of breakout. This was done to predict the orientation of major principal stresses in the horizontal axis, with the results being further validated by the geometry of stress-induced core disking. From the lab material properties and breakout geometries, a continuum based, back analysis of breakout was done through the creation of a generic database of stress dependent numerical models. When compared with the in situ breakout profiles, this created an estimate of stress as a function of depth along each hole. The consideration of the presence of borehole fluid on the estimate of stress was also made. This provided the upper-bound estimate of stress from this methodology. Given the generic nature of the numerical models, potential shaft overbreak was also assessed using this technique and from the previously described estimate of stress.

abstract: M.A.Sc.


title: Spreading Depolarization in the Early Post-Ischemic Brain

contributor:
Andrew, R. David
Jin, Albert
Neuroscience Studies

subject:
Golgi Stain
Post-Ischemic Electrophysiology
Middle Cerebral Artery Occlusion (MCAo)
Carbetapentane
Dibucaine
Sodium-Potassium Pump
Adenosine
Spreading Depolarization
Ouabain
Ischemia
Infarction
Post-Ischemic SD Resistance

abstract:
Stroke is one of the leading causes of death and long-term disability throughout developed countries. A propagating wave of mass depolarization of neurons and glia, referred to as spreading depolarization (SD), occurs within minutes after insufficient blood supply expands brain territory with depleted ATP and tissue damage. By harvesting live brain slices from mice that underwent focal stroke via middle cerebral artery occlusion (MCAo), we were able to image the ignition site of post-ischemic SD, assess the precise spatiotemporal propagation of the accompanying wave and record brain tissue changes in response to further metabolic stress. Post-MCAo brain slices superfused with elevated [K+]ext, [glu]ext or oxygen-and-glucose deprivation (OGD) display a decreased propensity to generate SD and tissue swelling in response to these extracellular conditions evident following stroke in vivo. Although this observation is counterintuitive to the high incidence of spontaneous SD observed in vivo by others two hours following ischemia, it is concordant with an ensuing period of decreased SD incidence. Furthermore, carbetapentane or dibucaine pre-treatment significantly delay SD onset in post-ischemic cerebral slices, similar to their effects in non-stroke brain slices. The healthy tissue observed immediately post-MCAo in the future ischemic core rapidly deteriorates during the ensuing 12 hours of infarct maturation. Although dramatic evidence of infarction occurs 12 hours following ischemia, a small and diffuse subset of pyramidal neurons in neocortex survives within the core. How they are protected and if they continue to survive post-MCAo are two intriguing issues for future study.
     Overall, this thesis specifically assesses the initiation, propagation and tissue changes in response to isolated mediators of swelling and SD in the post-ischemic brain. The observations of a delayed latency to SD onset and decreased susceptibility of swelling of the early post-ischemic brain support previous hypotheses of an adaptive mechanism of the post-ischemic brain to prevent or limit further depolarizations. The post-ischemic resistance to SD was over-ridden by chemical blockade of the Na+/K+ pump (and SD induction) by 100 µM ouabain. This finding resonates with an initial hypothesis of SD resistance by Na+/K+ pump hyperactivation postulated by early investigators of SD.

abstract: PhD


title: The Analysis of Strainbursts in the Sudbury Region And Numerical Modelling of Destress Blasting

contributor:
McKinnon, Stephen
Mining Engineering

subject:
Mining Engineering
Strainbursting
Destress Blasting
Safety
Drift Development
Sudbury
Underground Mining
Rock Mechanics
Rock Stresses
Strainbursts
Destress Blasting

abstract: The practice of destress blasting to reduce the risk of strainbursting in mines has been used since the early 1950's. Understanding both the variability in causes of strainbursting and the method by which destress blasting could reduce its risk, will allow future researchers to develop better guidelines for destress blasting. This research examines records of strainbursts at three mines near Sudbury, finding that the current method of recording these events yields little information with a large amount of variability dependent on many factors. Significantly, a large proportion of the events had workers at the face at the same time as the events occurred, continuing to highlight the safety risk presented by strainbursting. In-situ trials were also completed, with numerical modelling finding that destress blasting could both increase and decrease stresses in the rock mass depending on the placement and damage zones of the explosive charges.

abstract: M.A.Sc.


title: A multifaceted investigation into the effects of acute exercise on indices of brain function

contributor:
Tschakovsky, Michael
Kinesiology and Health Studies

subject:
cognitive function
brain-derived neurotrophic factor
ERP
Reward positivity
EEG
neurotrophin
MRI
novel exercise
BDNF dose

abstract:
Participation in regular exercise is important for the maintenance and improvement of brain health across the life span.  These beneficial effects are realized almost immediately, as a single bout of exercise transiently improves cognitive function after cessation of exercise.  This post-exercise time period represents an opportunity to strategically prescribe cognitively stimulating activities for enhancing brain plasticity and function.  Mechanistically, acute exercise is proposed to upregulate brain-derived neurotrophic factor (BDNF) expression and increase regional activation and arousal of brain areas involved in cognitive control; however, the specific mechanisms underlying this facilitation are poorly understood.
Purpose: 1) To investigate BDNF responses to small muscle mass exercise in order to probe a potential mechanism of BDNF release during exercise. 2) To create and validate an equipment-free exercise protocol for use in a magnetic resonance imaging (MRI) scanner, with the eventual goal of investigating brain responses during exercise that may underlie improved cognition. 3) To determine the effect of a very brief bout of high-intensity interval exercise (HIIE) on neuroelectric indices of reinforcement learning in young adults.
Methods: 1) serum BDNF, platelet, and the amount of BDNF per platelet responses were measured following short-duration, maximal effort and long-duration submaximal effort forearm handgrip exercise.  2) We assessed the magnitude and reliability of metabolic responses to a novel whole-body isometric contraction (WBI) exercise protocol.  We also characterized the amount of head movement created by WBI.  3) The event-related potential component associated with reward-based learning was assessed before and after a bout of HIIE.
Results: 1) Forearm handgrip exercise significantly increased serum BDNF, platelets, and BDNF per platelet, suggesting the possibility of splenic and cellular contribution of BDNF in response to handgrip exercise.  2) WBI reliably evokes metabolic responses that are similar in magnitude to previous in-MRI studies, and creates head movement suitable for MRI scanning.  3) HIIE abolishes neuroelectric indices of reward learning, likely due to incomplete recovery from exercise.
Conclusions: These findings advance our understanding of neurochemical and neuroelectric responses to acute exercise and introduce a novel tool that stands to further elucidate the regional brain responses to exercise that may underlie enhanced cognition post-exercise.

abstract: PhD