title: The time course of changes in brown adipose tissue fat fraction during cooling and warming in adult males

contributor:
Morrison, Katherine
Medical Sciences

subject:
brown adipose tissue
magnetic resonance imaging
cold exposure
time course
humans

abstract:
Background: Brown adipose tissue (BAT) preferentially oxidizes stored triglycerides (TAGs) to generate heat during acute exposure to cold. However, the time course of its activation is not well described as we are currently limited to BAT measurements before and after an acute stimulus. Magnetic resonance imaging (MRI) is a preferred modality to uncover such evidence, as it estimates TAG content via fat fraction (FF), and permits repeat scans in the same subject. As such, serial FF measurements in a defined BAT region of interest during a uniform whole-body temperature challenge is warranted.

Objectives: The first objective of this study was to assess the pattern of change in supraclavicular (SCV) BAT and posterior neck subcutaneous adipose tissue (SAT; a region with an unestablished role in non-shivering thermogenesis) FF during a mild cold exposure in adult males. The second objective was to evaluate if indices of body composition were related to the pattern of cold-induced change in SCV BAT FF. The final objective was to assess the influence of warming immediately following cooling on these changes.

Methods: Twelve males between the ages of 19 and 28 were recruited to this cross-sectional study. Users of tobacco, nicotine, and/or alcohol, those with contraindications for magnetic resonance imaging (MRI), and diseases, surgeries, and/or medications associated with thermogenesis were excluded. There were two study visits in total. During the initial visit, anthropometric measurements were carried out in triplicate (i.e. height and weight to determine body mass index (BMI), and body composition measurements (i.e. % body total fat and lean mass (kg)) were obtained using Dual Emission X-Ray Absorptiometry. Within 30 days of this initial visit, subjects attended a time course MRI session. At this visit, participants underwent standardized cold (3-hours at 18°C) and subsequent warm (30 minutes at 32°C) exposures using a water-perfused suit while lying in a 3 Tesla MRI scanner, and the temperature of the water entering and leaving the suit was recorded throughout. FF in the SCV region and posterior neck SAT was measured at defined intervals during both temperature challenges. Separate time course plots of the mean reduction in FF from baseline were constructed for the cooling and warming phases. For the first objective, the rate and magnitude of FF changes in SCV BAT and posterior neck SAT over defined time intervals were determined through calculations of slope and area under the curve (AUC), respectively. Identification of the earliest point of change from baseline, and the point at which changes were no longer different from those measured after 3 hours of cooling, were accomplished through paired comparisons using a random-slope linear mixed model with measures at 0 minutes and 180 minutes used as the reference values, respectively. A random-intercept multilevel regression model was used to define the cold-induced change in FF over time. For the second objective, a Spearman rank-order correlation assessed the association between indices of body composition (i.e. BMI and % total body fat) and indices of BAT activity (i.e. AUC and FF reduction) at time points of interest as identified by objective 1.

Results: The mean±SD of BMI, LMI, and % total body fat were 24.7±2.8kg/m2, 17.6±1.6kg/m2 and 25.0±7.4%, respectively. Seven of the twelve subjects completed three hours of cold exposure (58.3%), and a further five endured at least one hour. A significant cold-induced reduction in SCV BAT FF was detected at 10 minutes following the onset of cold exposure (mean difference = -1.6%; p=0.005), and changes in FF beyond 30 minutes of cooling were similar to those measured after three hours (p<0.05). Meanwhile, the posterior neck SAT did not experience significant cold-induced changes in FF. A novel attempt at identifying a quadratic model to predict one’s BAT-specific response to a cold challenge was carried out, and the intercept, time, time2, and intraclass correlation coefficient (i.e. parameters which described the relationship between FF and time) were highly significant (p<0.001). Although every participant had a measurable decline in FF, those with a higher BMI and % body fat had a smaller magnitude of change throughout the time course. In particular, a strong negative correlation between BMI and AUC FF decline existed as soon as 10 minutes following the onset of cold (rho=-0.786), indicating that those with a lower BMI had a larger magnitude of change in SCV BAT FF at this point. Finally, warming did not visually influence the trajectory of SCV BAT FF.

Limitations: Only seven of the twelve participants completed the full 180 minutes of cold exposure, which further limited the already low statistical power of this study. Moreover, complementary measures of BAT activity, such as energy expenditure, and objective measurements of shivering, such as electromyography, could not be evaluated.

Conclusions: These findings suggest that significant cold-induced changes in BAT FF occur much sooner than three hours. Thus, a shorter duration of cold exposure may be considered in future studies using MRI to detect BAT activity, as this could increase the feasibility of gathering larger and younger sample populations.

abstract: Thesis

abstract: Master of Science (MSc)


title: A Learning Factory Case Study: Industry 4.0 Digital Foundation

title: Industry 4.0 Digital Foundation

contributor:
Elbestawi, Mohamed
Mechanical Engineering

subject: Industry 4.0

abstract: The fourth industrial revolution is the extension of the third digitization revolution in terms of integrating computers and software to transform manufacturing to become green, customizable, on demand, and as a service. In the work done below, we elaborate on the information and communication technology architecture enabling this revolutionary transformation. We show the way to move forward with technology from as low level as sensors and all the way up till we reach services and customization. All this work is done under the roof of a learning factory establishment, which yields the way for not only knowledge transfer and hands-on experience, but also research and development in collaboration with market-leading software, hardware, communication, and manufacturing companies.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: PHYSIOLOGICAL ADAPTATION ASSOCIATED WITH TRANSFER OF MICROBIOTA FROM EXERCISE-TRAINED MICE INTO GERM-FREE MICE

contributor:
Parise, Gianni
Kinesiology

subject:
gut bacteria
germ-free
microbiota
endurance exercise
gnotobiotic
inoculation

abstract: Exercise is known to induce changes in the gut, typically referred to as the ‘forgotten organ’, and changes in gut microbiota can also occur with exercise possibly imparting systemic benefits. The question remains whether or not microbiota from an exercised animal can independently affect skeletal muscle morphology. Our first objective was to examine whether an endurance exercise program could modify the microbiota in donor mice. Second, we aimed to elucidate if such an endurance-trained microbiota could be transferred to germ-free mice via fecal inoculation. Finally, we sought to determine how the morphology and functional characteristics of skeletal muscle were influenced as a result of fecal inoculation. We hypothesized that germ-free mice recipients inoculated with the microbiota from endurance trained donors would undergo morphological changes in muscle fibre type composition and physiological changes in skeletal muscle function associated with a more oxidative phenotype. Eight-week-old male C57BL/6NCrl donor mice (n = 20) were randomized into two groups: one group completed an endurance exercise training protocol on a treadmill machine 3x/week for 11 weeks (n = 10) while one group remained cage-bound (n = 10). Ten-week-old male (n = 7) and female (n = 9) germ-free mice were colonized with the cecal microbiota of the donor mice in that, equal numbers of germ-free mice were inoculated with exercised-microbiota as sedentary-microbiota. Glucose metabolism and performance measures were evaluated in the donors as well as the recipients post-inoculation. Muscle tissue was extracted for immunohistochemistry and mitochondrial assays. During the intra-peritoneal glucose tolerance test (IPGTT), significant differences in blood glucose were found at 30min between exercise-inoculated and sedentary-inoculated (23.4 ± 2.2; 29.0 ± 1.9 mmol/L, p<0.05).and change in blood glucose relative to baseline (12.04 ± 2.4; 18.3 ± 1.9 mmol/L, p<0.01). There were significant sex-based differences in the blood glucose response in inoculated animals such that there were significant differences in blood glucose between the exercise-inoculated females and sedentary-inoculated females at 15mins (28.4 ± 2.4; 30.6 ± 1.1 mmol/L, p<0.05) and 30mins (24.7 ± 3.6; 29.9 ± 2.4 mmol/L, p<0.01), however no differences between exercise-inoculated males and sedentary-inoculated males. In addition, there were significant differences in the change in blood glucose relative to baseline between the exercise-inoculated females and sedentary-inoculated females at 15mins (12.3 ± 1.9; 20.6 ± 0.8 mmol/L, p<0.01) and 30mins (10.2 ± 2.6; 19.9 ± 2.1 mmol/L, p<0.001). This novel characterization of a link between gut microbiota and skeletal muscle suggests a transmissible capacity of microbiota to impart properties of ‘healthy’ muscle into compromised populations.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: The gut microbiome or microbiota describes the composition of the human gut – remarkably, over 100 trillion bacterial cells live in symbiosis with the cells of the human body. Research from the past decade has elucidated the salient nature of the human gut microbiome on immunity, metabolic homeostasis, and overall health and disease. Transformative research in the field has demonstrated the ability to transfer these bacterial colonies from one individual to another and elicit change, such as altering body mass and adiposity, respective to their donor. The interaction between gut microbiota and other organ systems i.e. brain, liver, adipose tissue has been the focus of several recent investigations, suggesting that lifestyle changes such as diet and exercise can influence communication between the gut and various other organs and contribute to changes in function. Skeletal muscle is the largest muscle in the human body accounting for 40% of total mass and although the main role of skeletal muscle is locomotion and postural stabilization, it is integral for the regulation of blood glucose as well as a reservoir for other macronutrients. Acute and chronic physical exercise cause a myriad of adaptive responses throughout the human body including in skeletal muscle and the gut. Therefore, the existence and influence of a gut-muscle link or ‘axis’ on human health cannot be ignored. What is unclear exactly, is if exercise-induced adaptations in the gut of an individual can be transferred to elicit change in the gut of a recipient and further induce adaptations at the level of the skeletal muscle.


title: Structure-Activity Studies of Cationic Bilayer Stabilizing Inhibitors of Protein Kinase C

contributor:
Epand, Richard
Biochemistry

subject:
activity
cationic bilayer
protein
kinase c

abstract:
Several compounds possessing diverse chemical structures have been shown to inhibit the action of protein kinase C (PKC). A general property of some of these compounds is that they inhibit bilayer to hexagonal phase interconversion in
phosphatidylethanolamine bilayers. In addition, a large number of PKC inhibitors are positively charged. To clarify the relationship between charge and enzyme inhibition, the effect of the cationic amphiphile sphingosine was studied at different pH's. Inhibition by sphingosine was found to be pH dependent. Above pH 7.75, sphingosine has little or no inhibitory effect. In fact, at pH 8.5 sphingosine slightly enhances enzyme activity above that which occurs when the enzyme is stimulated by diacylglycerol and phosphatidylserine. After correcting for electrostatic repulsion, the intrinsic pK for sphingosine in Triton micelles is 8.5. Inhibition of PKC by sphingosine at physiological pH's therefore correlates with the presence of positive charge. In an attempt to optimize the structural features necessary for inhibition of PKC, a number of compounds which incorporate both positive charge as well as bilayer stabilizing ability were designed. These compounds possess a hydrophobic backbone which does not perturb hydrocarbon packing and have a tertiary or quaternary nitrogen functionality in the head group. All designed amphiphiles inhibit PKC activity; the potency of the amphiphile correlates with the presence of positive charge. Quaternary ammonium bilayer stabilizers are 10 fold more potent than their tertiary amine precursors, generally inhibiting in the 10 - 60 (mu)M range using the Triton mixed micelle assay. Aside from charge, factors such as the structure of the amine containing head group and its length from the hydrocarbon moiety did not markedly influence inhibitor potency. In contrast, the hydrocarbon backbone did influence potency. Cationic amphiphiles containing asteroid backbone were more potent than their straight chain analogues. These amphiphiles do not appear to alter the partitioning of PKC from the aqueous phase to the membrane surface. A number of bilayer stabilizing compounds possessing carboxylate and sulfate anions in addition to the quaternary nitrogen functionality were also designed. Although inhibitor potency correlated with the amount of charge present on the amphiphile, charge could not account for all the observed effects. Changes in the position of the charged functionalities and hydrocarbon length resulted in marked differences in amphiphile potency. Some inhibited in the submicromolar range. The results of these studies suggest that a combination of positive charge and a bilayer stabilizing structural characterisitic provides a basis for the rational design of PKC inhibitors.

abstract: Thesis

abstract: Master of Science (MS)


title: Factors Influencing the Acquisition of a Timed Sequential Movement

contributor:
Lee, Timothy
Adapted Human Biodynamics

subject:
timed sequential movement
time
movement
acquisition

abstract: Two experiments are reported that assess the effect two types of training (phase and duration) have on the acquisition and transfer of timed sequential movements. The first experiment showed that phase-training (practicing segment movement time goals) facilitated phase transfer over duration-training (practicing overall movement time goals). When the kinematics of the phase transfer test were altered in the second experiment, no transfer differences were found between phase and duration-trained groups. These findings are discussed in reference to contextual interference effects and the learning of essential variables. Also, the importance of kinematics and segment relationships to essential variables are evaluated.

abstract: Thesis

abstract: Master of Science (MS)


title: In situ Transmission Electron Microscopy Characterization of Dynamic Processes Involving Nanoscale Materials

contributor:
Botton, Gianluigi
Soleymani, Leyla
Biomedical Engineering

abstract:
The characterization of nanomaterials involved in dynamic processes are conventionally conducted using microscopy, spectroscopy and other physical/chemical methods through the pseudo-dynamic approach. In details, the dynamics processes are recorded by repeating or terminating the process multiple times. However, the above approach can lead to missing important transition information and inducing contamination for mechanistic studies. This motivates the efforts to develop real time characterization techniques which can probe the dynamic change of nanoparticles in their native operating environments. With the capability of probing structural change at the nanoscale, in situ transmission electron microscopy, has shown great potential in studies and applications of various processes. Targeting at conducting precise analysis, which has been limited by many uncertainties from electron beam effects and the miniaturized reaction cell used for TEM, the work presented herein pursues a quantitative characterization of a few electrochemical and biological processes through in situ liquid-phase transmission electron microscopy.
In this work, the in situ transmission electron microscopy system is evaluated by comparing the in situ results with those from standard experiments to show its capabilities in studying dynamic processes. The in situ system is quantitatively calibrated to obtain the optimized observation conditions to avoid detectable electron beam interference, solution depletion and achieve sufficient resolution for analysis through micrometer thick liquid. These form the fundamentals for the in situ studies. Moreover, a comprehensive analysis protocol is established by incorporating multiple ex situ and post situ characterizations.
Using this optimized in situ system, the mechanism of electrodeposition of gold on carbon electrode is studied. The in situ results allow quantitative analysis of the growth process. The prevailing diffusion limited three dimensional growth model is examined. A study of the effect of supporting electrolyte on the electrodeposition of palladium is also conducted. The self-limiting, surface diffusion and aggregation/recrystallization growth model is found to describe the early stage of growth, rather than the classical Volmer-Weber growth model. A further study is conducted on the structural evolution of palladium nanoparticles under electrochemical cycling. The mechanisms involved in this process, including electrodeposition, dissolution, hydrogen co-deposition and hydrogen desorption, are studied. The supporting electrolyte, HCl, is found to enhance the dissolution of deposited palladium clusters and induce movements and aggregation of the deposits during the hydrogen interaction process to form chain-like and irregular clusters, which provide direct experimental proof on the morphology formation of palladium with hydrogen involvement. Ultimately, the in situ technique is applied to the study of calcium phosphate biomineralization. Combined with multiple post situ characterization techniques, the study provides direct experimental evidence of the non-classical pre-nucleation and attachment growth of calcium phosphate structures. This demonstrates the potential of the in situ technique for studying the mechanisms involved in biological processes.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)

abstract: Nanostructured materials have been widely used in various fields. In situ transmission electron microscopy, a technique used to characterize nanomaterials involved in different dynamic processes in their operating environments, is an advanced tool over the traditional characterization methods such as ex situ microscopy and spectroscopy. However, there are several challenges in applying this in situ technique to processes occurring in liquid media. In this thesis, an in situ transmission electron microscopy system is applied to study the mechanisms of structural changes during different processes in liquids with both high spatial and temporal resolution. Protocols to evaluate and optimize the in situ system are developed to provide results comparable with those from their actual applications. Then in situ studies on the structural evolution of nanomaterials during electrochemical processes are performed and different theoretical models are applied to describe these processes. Finally, this technique is extended to investigate biomineralization to show its capabilities in future studies on biological processes.


title: Adaptation to Repeated Eccentric Exercise in Males and Females

contributor:
Tarnopolsky, Mark
Phillips, Stuart
Kinesiology

subject: eccentric exercise male female adaptation

abstract:
Unaccustomed eccentric exercise results in damage to skeletal muscle ultrastructure. One bout of eccentric exercise can induce adaptations in skeletal muscle, such that if the bout is repeated indices of muscle damage are attenuated. However, little is known about the pathways mediating these "protective" adaptations. The purpose of this thesis was to further characterize adaptations to repeated eccentric exercise and to investigate the hypothesis that increased stress protein content is associated with attenuated indices of muscle damage following the second exercise bout. Untrained male (N = 8) and untrained female (N = 8) subjects performed two bouts of unilateral, eccentric leg press and unilateral, eccentric knee extension exercises separated by 5.5 wk. Biopsies were taken from the vastus latera/is of the exercised and control (rest) leg. Blood samples and strength data were also collected. Following the second exercise bout the rise in serum CK activity, the post exercise force deficit and the extent of ultrastructural disruption as characterized by Z-disk streaming were attenuated, however ubiquitin conjugated protein content was elevated. Serum CK activity was lower in females as compared to males and ubiquitin conjugated protein content was greater in males as compared females. No gender difference was detected in the extent of Z-disk streaming or the relative magnitude of post exercise force deficit. Muscle macrophage counts were elevated over
resting values 24 h post exercise bout 1 and 2 in both males and females. Whereas, neutrophils counts were only elevated over resting values following the second exercise in females. HSP72 protein content did not change in response to eccentric exercise, but it tended to be greater in males as compared to females (p=0.053). HSP27 protein content increased in response to exercise in males only, although females had greater basal content. Following the second exercise bout bcl-2 protein content was greater in females as compared to males. In conclusion, adaptations to repeated eccentric exercise are associated not only with attenuated serum CK activity and force deficit as previously described, but also with decreased ultrastructural damage, increased ubiquitin conjugated
protein content and changes in stress protein content.

abstract: Thesis

abstract: Master of Science (MS)


title: Exploring the Assessment of Inflammation and Erosion in the Metatarsalphalangeal Joints of patients with Early Rheumatoid Arthritis Using Clinical Examination, Ultrasonography and Magnetic Resonance Imaging

title: Imaging Assessment of Rheumatoid Arthritis

contributor:
Larche, Maggie
Beattie, Karen
Medical Sciences

subject:
arthritis
rheumatoid arthritis
imaging
medical imaging
ultrasound
MRI
inflammation
bone erosion

abstract:
Introduction
Disease monitoring in rheumatoid arthritis (RA) can be improved by incorporating imaging technologies. Clinical examination fails to detect subclinical inflammation in half of metatarsophalangeal joints (MTPJs), but the effectiveness of using ultrasonography (US) in MTPJs is unclear. We aimed to evaluate US assessment of disease activity in the MTPJs using MRI as the reference standard, in comparison to clinical examination.
Methods
Patients newly diagnosed with RA (ACR criteria) were recruited and assessed at baseline, 6 weeks, 3 months, 6 months, and 12 months. A rheumatologist assessed the MTPJs 2-5 bilaterally for swelling and tenderness (presence=1), and for erosion (presence=1), synovial thickening, and power Doppler (PD) by US. Synovial thickening and PD were graded semi-quantitatively (grade 0-3). The most clinically symptomatic foot was scanned using extremity MRI (1.0T) at the baseline and 12-month visits. MTPJs 2-5 were graded semi-quantitatively for synovitis, bone marrow edema (BME) (grade 0-3), and erosions (grade 0-10).
Results
Forty-one patients were recruited (mean (SD) age=51.9 (10.3) years, 81% female). Kappa agreement was moderate between PD and grade ≥2 synovitis (k=0.46) and BME (k=0.47), but poor agreement was found for clinical examination and synovial thickening. US was able to visualize subclinical inflammation in 41% of non-swollen joints. After 12 months, the average total score for synovial thickening, PD, and BME all significantly decreased, but not swollen or tender joint counts. US visualized few erosions (n=8) compared to MRI (n=101) in the most symptomatic foot. MRI observed erosion repairs in patients treated with DMARDs, and repairs appeared to be preferential for MTPJs that had low inflammation seen by US.
Conclusion
US appears to better visualize MTPJ inflammation than swollen and tender joint counts, and may be used in combination with clinical examination to improve routine disease monitoring in RA.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: Current assessment of rheumatoid arthritis (RA) relies on physical examination for joint swelling and tenderness, but these methods often miss underlying inflammation. Ultrasonography (US) may help improve the diagnosis and monitoring of disease activity, but its effectiveness in imaging the feet is unclear. With MRI (another imaging technology) as the standard of reference, we compared the use of physical examination and US in assessing inflammation in the feet, and explored the potential of using US to see damage to bones. In 41 patients with early RA (<2 years of disease), US was able to detect inflammation in many joints that appeared normal, and was better at detecting decreased inflammation over 1 year than physical examination. Although US was limited at assessing early bone damage, it was able to see several large erosions. In conclusion, US can better visualize disease activity than clinical examination and can improve RA assessments.


title: Is Hypoxic (Altitude) Training More Effective than Sea Level Training for Competition at Sea Level?

contributor:
MacDougall, J. D.
Human Biodynamics

subject:
hypoxia
competition
training
sea level
altitude

abstract:
The purpose of the present study was to determine whether or not the combination of normobaric hypoxia and exercise training would enhance adaptations in skeletal muscle over and above that which occurs with the same amount of training under normoxic conditions. Also investigated was the effect of such training conditions on performance as assessed by V0_2max and maximal aerobic capacity (MAC). Ten males performed unilateral cycle ergometry training
3 times per week for 8 weeks so that one leg was trained under normoxic conditions and the other while breathing an hypoxic gas mixture (FI0_2= 13.5%; equivalent to an altitude of 3,292 meters). Absolute power output was kept constant for both conditions and subjects performed both continuous (75% pre-training maximal power output) and interval (100% pre-training maximal power output) training. Needle biopsies were taken from the vastus lateralis of both legs to assess pre- and post-training differences in morphometric and biochemical data. Performance measures included V0_2max and MAC (time to fatigue at 95% pre-training maximal power output) for each leg. Significant increases in V0_2max (p <0.05) occurred in
both legs with higher peak ventilation and blood lactate concentrations (p <0.05) post-training. Marked improvements (p <0.05) in MAC were also seen with an increase of 402% in the normoxically-trained leg and 513% in the hypoxically-trained leg. Citrate synthase (CS), succinate dehydrogenase, and phosphofructokinase activity was significantly (p <0.05) higher in both legs following training with a significantly greater (p <0.05) increase in CS in the hypoxically-trained leg. There were no differences in capillary/fiber ratio, capillary density,
fiber area, fiber type, and mitochondrial volume density for either condition, pre- or post-training. It is concluded that hypoxia enhanced the muscle oxidative capacity (as marked by cs activity) but was unable to improve performance over and above that which occurs with the same training at sea level.

abstract: Thesis

abstract: Master of Science (MS)


title: The Contribution of Below Knee Wobbling Mass to the Estimation of Vertical Knee Joint Reaction Forces Following Impact with the Ground

title: The Effect of Wobbling Mass on Knee Joint Force Estimates

contributor:
Dowling, J. J.
Biomechanics

subject:
knee
knee wobble
vertical knee joint
joint
impact ground

abstract: In human impacts involving high peak accelerations, the wobbling mass (skin, muscle, fat, and connective tissue) of the body will accelerate independently of the rigid mass (bone) . The purpose of this study was to quantify the effect that below knee wobbling mass has, if any, on the attenuation of peak forces transmitted through the leg to the knee joint, following impacts with the ground. Fifteen healthy subjects dropped vertically from heights of 5 and 10 cm, onto a force platform, with the ankle and knee joints of the support leg held rigidly. A uni-axial accelerometer was fixed, with skin bond cement, to the skin overlying the anterior upper tibia, and another to the posterior wobbling tissue of the support limb. Vertical ground reaction forces and accelerations were used in rigid only and rigid and wobbling link segment models of the leg, which resulted in estimates of vertical knee joint reaction forces (VKJRF). Mean peak VKJRFs resulting from rigid only calculations were 2.66±.55 x body weight (bw) and 3.53±.68 x bw, and from rigid and wobbling calculations were 2.64±.55 x bw and 3.52±.68 x bw, for the 5 and 10 cm heights, respectively. A two-way, repeated measures ANOVA revealed that there was no main effect for calculation method. Validation of the subject results was attempted indirectly by comparing them to the actual forces (load cell) at the knee of a manufactured model. The model was constructed in proportion to a human subject of mass 75 kg. When the model was dropped from the same heights as the subjects, the mean peak VKJRFs (22. 9 x bw) greatly overestimated the actual load cell values (8.2 x bw), and were unrealistic relative to subject values (approximately 3.0 x bw). Although mean peak VKJRFs were also overestimated when the wobbling mass accelerations were included, they were much closer to the actual values (9.9 x bw vs. 8.2 x bw).

abstract: Thesis

abstract: Master of Science (MS)


title: An Efficient Numerical Model for Solving the Single Electron Band Structure in Si Based on the Self-Consistent Pseudopotential Method

contributor:
Li, X.
Deen, M. J.
Electrical and Computer Engineering

subject:
electron
electron band structure
si
pseudopotential
numerical model

abstract:
The electronic band structure of a semiconductor is an essential property to determine most of its optical characteristics. The complexity of the energy band structure calculations makes analytical calculations impossible. Any calculation leading to electronic band structures has to utilize numerical methods. In this thesis, two solvers were developed to calculate the energy band structure of 1D Kronig-Penney lattice, 30 diamond lattice-structure and silicon lattice. In this thesis, many of the important methods of calculating the energy band structures were discussed. Through comparisons among different methods, we have determined that Self-Consistent Pseudopotential Method, SCPM, is the most suitable method for calculating the energy band structures when self-sufficiency and accuracy are of special importance. The SCPM is an iterative method which was utilized in this thesis by using efficient numerical methods. Instead of using conventional numerical methods such as Finite Difference Method or Finite Element Method which cause inefficiency, this thesis calculates the energy band structure by utilizing Orthogonal Plane-Wave expansion of the potentials. The 1D electronic band structure solver was developed as a foundation for the implementation of the 30 electronic band structure solver. It uses a minimal number of Fourier coefficients to calculate the energy band structure of the 1D Lattices without compromising accuracy. The 30 electronic band structure solver development needs multiple changes and modifications to the 1D solver. As the 30 solver is essentially made using the 10 solver platform, it is also efficient and needs a minimal number of Fourier coefficients for accurate results. The 30 solver can be used for either Nearly Free Electron Method, NFEM, or SCPM
calculations. The NFEM calculations were done on the diamond lattice structure. The results were shown to be the same as the benchmarks of [28, 80]. The silicon lattice energy band structure was also calculated with the 30 solver using SCPM with LOA. The results were in the same range as the four sets of data gathered from three benchmarks [58, 81, 82], showing good agreement. Based on the two comparisons made for the 30 solver, it was shown that it is a reliable and efficient program to calculate energy band structures of the 30 lattices.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Characterization of Hypotonic Shock Induced Ascorbate Release from Pig Coronary Artery Endothelial Cells

contributor:
Grover, A. K.
Biology

subject:
hypotonic shock
ascorbate
pig
coronary artery
endothelial cell

abstract:
Ascorbate (Asc) is a key antioxidant in preventing cardiovascular dysfunction during diseases exacerbated by altered shear stress. According to the literature endothelial responses to hypotonic shock share some characteristics with those induced by shear stress. Thus to study the physiological responses of endothelium to shear stress, the characterization of the Asc release by pig coronary artery endothelial cells in response to hypotonic shock was performed.
The pig coronary artery endothelial cells that had been loaded with ^14C Asc and ^3H deoxyglucose, were exposed to buffers of varying osmolality for different time periods and the release of ^14C Asc and ^3H deoxyglucose was examined. Based on various parameters like relative release of ^14C Asc and ^3H deoxyglucose, their rate of release and protein loss, it was decided to use buffer of .67 percent osmolality for 2 min for these characterization studies. The Asc release was authentic and not a result of membrane damage. The hypotonic shock induced Asc release was not due to endogenously released ATP. The inhibition of ATP induced release by anion channel inhibitors niflumic acid and NPPB was complete but only partial in case of hypotonic shock induced release. The release was not inhibited under nominally Ca^2+ free conditions. Additive release by hypotonic shock and ATP or hypotonic shock and Ca^2+ ionophore A23187 suggests that there are two independent Asc release pathways. Asc release by two different mechanisms may help endothelial cells deal with stressful conditions efficiently and preserve endothelial function.

abstract: Thesis

abstract: Master of Science (MS)


title: Ascorbate Transport in Coronary Artery

subject:
ascorbate
coronary artery
transport

abstract: Vitamin C (ascorbate or Asc) is an essential vitamin for humans. The transport of oxidized ascorbate occurs via Na^+-dependent vitamin C transporters (SVCTI/SVCT2). Ascorbate is a powerful antioxidant that may be beneficial in scavenging the reactive oxygen species associated with cardiovascular diseases. The objectives of this thesis were: to identify the SVCT isoform(s) expressed in pig coronary artery smooth muscle and endothelium, to determine if preloading cultured pig coronary artery smooth muscle cells with ascorbate protects them against oxidative stress, and to overexpress SVCT2 in these cells to see if an increase in ascorbate reserve helps protect the cells even more. Pig coronary artery smooth muscle tissue and cells cultured from the same tissue express SVCT2 and not SVCT1. Cultured pig coronary artery endothelial express SVCT2, however the limited amount of fresh endothelium isolated, restricted us from determining the isoform present in the fresh tissue. Ascorbate preloading (200 (mu)M overnight) did not decrease the damage caused by hydrogen peroxide as measured by oxidation of dichlorodihydrofluorescein diacetate or mitochondrial reductase activity. The mRNA and ^14C-Asc uptake was marginally greater in pig coronary artery smooth muscle cells stably transfected with a linear pcDNA3.1 SVCT2 plasmid than mock transfected controls. The ^14C-Asc uptake was 1.5 times greater than mock transfected cells after 60 min. A new SVCT2 plasmid, that contained SVCT2 coding region only, did not show greater ^14C-Asc accumulation compared to the plasmid that had the entire SVCT2 cDNA in transiently transfected HEK293T cells. This thesis is a beginning towards further study on the molecular and physiological role ascorbate plays in the coronary artery.

abstract: Thesis

abstract: Master of Science (MS)


title: A Neural Network Based System to Classify the DNA Promoter Sequences of Escherichia Coli

title: Neural Network System to Classify DNA Sequences

contributor:
Harley, Calvin
Computation

subject:
neural network
DNA
DNA promoter sequence
e. coli
escherichia coli

abstract: In this project, a neural network based system is used to classify the promoter regions found in Escherichia coli DNA sequences. An unsupervised algorithm based on the self-organizing feature map is used to classify the sequences and a dynamic programming algorithm is used too query the trained neural networks. In order to generalize the neural network's weights for display purposes, a back propagation supervised learning algorithm based on the conjugate gradient method is used to map the weights to one of the fifteen combinations of adenine, cytosine, guanine, and thymine (the chemical components of DNA). The results show that this method is able to classify the training sequences into discrete sub-classes which provide a query base for classifying new sequences. This method can be used for any class of sequences and can be extended for use in searching sequence databases.

abstract: Thesis

abstract: Master of Science (MS)


title: Detecting Locus-Locus Interactions Using Microarray Data

contributor:
Canty, Angelo
Statistics

subject:
locus-locus
microarray
microarray data

abstract: In this report we explore how to find the locus-locus interaction using microarray data. Our analysis makes use of a dataset from an experiment with Affymetrix GeneChip MGU74Av2 for mice. In Chapter 1 we give the genetics background, an introduction to microarray methodology and the preprocessing of microarray data, and a review of SAM (Significance Analysis of Microarrays) method for finding differentially expressed genes in microarray data. In Chapter 2 we describe our dataset and our objective of finding the genes with locus-locus interaction but with no main effect. We also show how to find the interaction in this chapter. In Chapter 3 we show the simulation study of detecting the locus-locus interaction without main effects and propose a two-stage method of doing that. In Chapter 4 we apply the two-stage method to the microarray data and focus on the second stage analysis. In Chapter 5 we examine an alternative method using bootstrap resampling in place of permutations. Chapter 6 contains our conclusion and some suggestions for future research.

abstract: Thesis

abstract: Master of Science (MS)


title: Sequence Alignments on a Multi-Transputer System

contributor:
Jiang, Tao
Computational Engineering and Science

subject: sequence multi-transputer system alignment

abstract: This thesis is concentrated on parallelizing a sequential algorithm for finding k best non-intersecting local sequence alignments. In this thesis, the DNA local sequence alignment and the related problems are formally defined and efficient algorithms for solving these problems are presented. The problem have important applications in molecular biology. Based on the analysis of the characteristics of the local sequence alignment problem and a multi-transputer system, the problem was partitioned into subproblems and nicely mapped onto the transputer nodes. Then, an efficient parallel program is designed and implemented. By comparing the outputs of the sequential program and the parallel program, the performance of the parallel program is estimated. An average speedup of 6.3 is achieved on a 8-node configuration and an average speed-up of 11 is achieved on a 16-node configuration.

abstract: Thesis

abstract: Master of Engineering (ME)


title: Risk Mitigation and Management Strategies for Routing Hazardous Materials over Railroad Network in Canada

contributor:
Verma, Manish
Business

subject:
Risk Management
Analytics
Hazardous Materials
Emergency Response Planning
Railroad Transportation
Optimization
Traffic Estimation
Infrastructure Investment

abstract: Railroad transportation of hazardous materials (hazmat) has grown significantly in recent years in Canada. Although rail is one of the safest modes for hazmat transport, the risk of catastrophic events such as the Lac Mégantic train disaster, does exist. In this thesis, we study a number of measures to manage and mitigate the risk associated with rail hazmat shipments. First, we propose a methodology that makes use of analytics to dis-aggregate national freight data to estimate hazmat traffic on rail-links and at rail-yards in Canada. Further, a focused analysis is conducted on crude oil rail shipments to develop long-term forecasts and evaluate the impact of proposed pipeline projects. Second, we present an emergency response planning problem, aimed at the effective and efficient response to rail hazmat incidents. A two-stage stochastic programming problem is solved over part of the Canadian railroad network, which provides recommendations on where to locate response facilities, and which equipment packages to stockpile at each facility. Finally, we study infrastructure investment as a strategy to mitigate the risk associated with rail hazmat shipments. This strategy is based on building new railway tracks to provide alternative routes to the riskiest parts of the network. Given the hierarchical relationship between the decisions made by regulatory agencies and railroad companies, a bilevel programming approach is used to identify the optimal set of infrastructure investment options given an allocated budget. Our computational experiments show that significant network-wide risk reduction is possible if hazardous shipments are routed using some of the proposed alternative rail tracks.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Effects of Exercise or Physical Activity on Overweight and Obese Individuals With Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-analysis

contributor:
Tang, Ada
Rehabilitation Science

subject:
Chronic Obstructive Pulmonary Disease
Exercise
Obesity
Overweight

abstract:
Rationale: The prevalence of obesity among individuals with chronic obstructive pulmonary disease (COPD) is increasing, which contributes to further ventilatory limitations, and compromised exercise capacity, and health-related quality of life (HRQOL) compared to COPD alone.
Objective: To conduct a systematic review to evaluate the effects of exercise interventions on walking capacity, ventilatory parameters, anthropometrics and HRQOL in individuals with COPD and elevated weight.
Methods:  A search was conducted on March 16, 2018 of Embase, Medline, CINAHL, AMED and PsycINFO for controlled trials of exercise interventions, involving adults with any stage of severity and stability of COPD with concurrent obesity or overweight. Overall effects were determined with standardized (SMD) and weighted (WMD) mean difference, using Review Manager 5.3.
Results: Nineteen studies with 1716 participants (BMI mean ± SD 28.2 ± 5.1 kg/m2) were included. Exercise interventions were effective in improving walking capacity measured by the 6-Minute Walk Test (6MWT), Endurance Shuttle Walk Test and Incremental Shuttle walk Test (12 studies, 1215 participants, SMD 0.25 (95% CI [0.06, 0.43]); p=0.01), fat-free mass index (2 studies, 285 participants, WMD 0.33 kg/m2 (95% CI [0.21, 0.46]); p<0.00001), St. George Respiratory Questionnaire (6 studies, 648 participants, WMD -7.49 points (95% CI [-13.01, -1.98]); p=0.008) and Chronic Respiratory Disease Questionnaire Dyspnea (5 studies, 478 participants, WMD 0.51 points (95% CI [0.00, 1.02]); p=0.05), Emotion (4 studies, 404 participants, WMD 0.28 points, 95% CI [0.03, 0.54]); p=0.03), and Mastery domains (4 studies, 404 participants, WMD 0.31 points (95% CI [0.02, 0.59]); p=0.03). There were no effects on ventilatory parameters or anthropometric measures.
Conclusions: Exercise interventions were effective in improving walking capacity and HRQOL in individuals with COPD and elevated weight. There is an important opportunity to establish effective interventions to minimize the functional and health effects in this subset of the COPD population.

abstract: Thesis

abstract: Master of Health Sciences (MSc)


title: DEVELOPING A CRISPR-ASSISTED RNA PURIFICATION, PROTEOMIC METHOD TO IDENTIFY RNA- SPECIFIC PROTEIN INTERACTIONS

contributor:
Lu, Yu
Biochemistry and Biomedical Sciences

abstract: RNA regulation involves a complex interplay between RNA-sequence modulators and RNA-binding proteins (RBPs), many of which have yet to be identified for specific RNA species. The current methods to identify RBPs, however, are limited by their specificity, affinity and/or their ability to capture the dynamic protein interactions involved in RNA regulation. To overcome these limitations in the current RNA-RBP enrichment methods, we developed an in vitro and in vivo clustered regularly interspaced short palindromic repeats (CRISPR)-assisted proteomic method (CARP) to enrich specific RNA and therefore, its associated RBPs. In the in vitro CARP approach, we found there was ~3-6-fold enrichment of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) messenger RNA (mRNA), though this was accompanied by the retention of non-specific mRNA. Attempts to remove non-specifically bound species by the use of both potent and mild detergents resulted in a corresponding loss of GAPDH mRNA. In the in vivo CARP approach, we created and validated constructs expressing CRISPR components. Furthermore, we established a stable cell-line expressing halo-deactivated Cas9 and conditions for gRNA and PAMmer delivery in cells. We did not find a considerable enrichment of GAPDH mRNA with the in vivo CARP system. This is the first study to establish conditions for an in vivo CRISPR/dCas9 RNA-RBP enrichment tool and to examine, quantitatively, the RNA-specificity of the CRISPR/Cas9 system. Our findings suggest although there was enrichment of the target RNA by the in vitro CARP system, there are concerns of specificity to this approach, as dCas9 appears to promiscuously bind to RNA.

abstract: Thesis

abstract: Master of Science (MSc)


title: ACUTE EFFECTS OF ANTIBIOTICS ON GUT MOTILITY AND GUT-BRAIN NEURONAL SIGNALLING

contributor:
Kunze, Wolfgang
Medical Sciences

subject:
gut-brain signalling
gastrointestinal motility
antibiotics
enteric nervous system

abstract:
Associations between the use of antibiotics and altered brain function and mental illness are now well evidenced from animal models and clinical trials. Based on these findings, emerging research efforts have largely focused on how high-dose antibiotic- mediated perturbations of the gut microbiota result in altered neurophysiological and behavioural outcomes. However, these studies have not investigated whether antibiotics also act directly on the host nervous system. My central hypothesis is that high-dose antibiotics, as used in experimental models testing the modulatory role of the gut microbiome, can induce pathophysiological outcomes by direct interaction with enteric neuronal circuits.
I designed two sets of experiments to characterize the acute effect of high-dose antibiotics on gut motility and gut-brain neuronal signalling. The first experimental study aimed to determine whether acute exposure of the gastrointestinal tract to high-dose antibiotics directly modulates enteric neurons, with consequences for gut motility. To test this, I used enteric nervous system dependent motility reflexes, ex vivo, as an index of putative effects on the intestinal nervous system. The results of these experiments have shown that luminal antibiotics alter oral to anal propulsive peristalsis in a system where such motility is dependent on the enteric nervous system. The second study aimed to test whether these local effects modulate brain function and behaviour by altering responses of vagal afferent pathways. I performed single-unit recordings from the mesenteric nerve bundle in ex vivo preparations to test this research question. The results suggest that antibiotics can increase activity of extrinsic vagal afferent neurons largely through cholinergic synapses with myenteric IPANs.
The present work offers significant therapeutic implications, although its main relevance is in the interpretation of the experimental use of high-dose antibiotics on animal models and where effects on behaviour and the nervous system are attributed solely to alterations in the microbiome.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: Little is known about the mechanisms by which high-dose antibiotics produce changes in gut-brain signalling to negatively affect brain functions and behaviour. Although the general consensus is that these changes are caused by antibiotic-mediated perturbations of the gut microbiota, whether high-dose antibiotics also act directly on the nervous system remains a topic of debate. I have hypothesized that high-dose antibiotics, as used in experimental models associating pathophysiological outcomes to gut microbial changes, also produce adverse effects by direct modulation of enteric neuronal circuits. Indeed, our findings suggest that high-dose antibiotics directly signal to enteric neurons, which locally regulate gut motility reflexes and can transmit that information further to vagal neurons, to influence homeostatic regulation of brain functions and behaviour. This work offers novel therapeutic potential for antibiotics and advises careful interpretation of studies that have attributed effects of high-dose antibiotics solely to alterations in the gut microbiome.


title: Study of Rheological Properties of Biodegradable Polyesters

contributor:
Vlachopoulos, John
Chemical Engineering

subject: rheology properties biodegradable polyester

abstract:
Biodegradable polyesters are considered as one of the most cost effective and environmentally friendly solutions to waste-disposal problems associated with traditional thermoplastics. The technologies for converting the resins into useful items require knowledge about the rheological properties of these materials. Adequate rheological models are essential for the design and optimization of the process technologies. Rheological properties of two commercial biodegradable polyesters- poly(lactic acid) (PLA) and aliphatic-aromatic co-polyester (AAC) Ecoflex -have been investigated using parallel plate and capillary rheometers. Results from a study on the extrusion instabilities of biodegradable polymers are reported for the first time. The experimental studies found that the biodegradable polyesters exhibit pseudoplastic
(shear-thinning) behaviour and the Cox-Merz rule is obeyed. A Cross model was proposed to describe their shear-thinning behaviour. The viscosity of both PLA grades is more temperature sensitive than the viscosity of Ecoflex. It was observed that the extensional viscosity of Ecoflex is larger than that of PLA and that the extensional viscosity of biodegradable polymers is similar to that of LLDPE. The experimental results indicate that biodegradable polymer melts slip at the die wall. It was observed that with increasing shear rate PLA exhibits sharkskin and gross melt fracture while Ecoflex exhibits only gross melt fracture. With regards to flow instabilities PLA behaves like linear polyolefins, however without exhibiting stick-spurt phenomenon. While Ecoflex behaves like branched LDPE, its gross melt fracture starts at higher values of wall shear stress than LDPE. Both biodegradable materials exhibit small extrudate swell: up to 28% for PLA and up to 34% for Ecoflex, which is comparable to that of rigid PVC. It was observed that biodegradable polymers substantially degrade during extrusion processing. It was also found that blending PLA and Ecoflex produced
immiscible blends. Melts of these blends exhibited sharkskin and gross melt fracture at higher shear stresses than the neat resins. This effect was attributed both to degradation during blending and to some sort of lubricating effect.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Properties of Thermoplastic Starch/Poly (Lactic Acid) Blends

contributor:
Hrymak, Andrew
Liu, Qiang
Chemical Engineering

subject:
thermoplastic
thermoplastic starch
thermoplastic poly blend
lactic acid

abstract:
Properties of plasticized thermoplastic com and pulse starches and their blends with poly (lactic acid) (PLA) were studied. Water and glycerol acted as plasticizer components for a ratio of starch/glycerol/water (wt/wt) fixed at 50/36/14 based on previous studies. PLA was used in blends to improve the properties of thermoplastic starch (TPS). Maleic anhydride (MA) was used as a coupling agent to increase the miscibility of PLA and TPS phases. Cloisite 30B, a type of organoclay, was added into the material system to improve the properties of blends. In order to enhance the hydrophobicity, alkyl ketene dimmer (AKD), used as a sizing agent, were introduced to material system. Both internal and surface sizing methods were applied. Measurements of rheological and mechanical properties were performed on a Rosand capillary rheometer and Instron tensile testing machine. The thermal and morphological properties of blends were characterized using differential scanning calorimetry and scanning electron microscopy. The contact angles were measured using a goniometer equipped with a video camera and a computer with drop shape analysis software for calculating the contact angles. The use of maleic anhydride as a coupling agent significantly improved the tensile strength and modulus of blends and the blend morphologies were more homogeneous. Improvements in tensile strength and modulus were achieved as Cloisite 30B nanoclay was used as a filler in TPS/PLAgMA blends. Some hydrophobicity was obtained for blends with Cloisite 30B. Blends ofTPS/PLAgMA/clay showed shear-thinning behaviors
at 150°C . .

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Exploring Interoception

contributor:
Shore, David I.
Psychology

subject:
interoception
body ownership
body awareness
rubber hand illusion (RHI)
heartbeat perception (HBP)
exteroception
MAIA
GERT
emotion
multisensory
psychology

abstract: Body ownership is a complicated and multifaceted percept. Although we subjectively perceive body ownership to be a stable component of our identity, recent work has illustrated that body ownership is a dynamic construct that is constantly updated by the integration of current endogenous and exogenous body-related information. The goal of this study was to explore the relation between these endogenous (interoceptive) and exogenous (exteroceptive) channels of information. We investigated this by using a heartbeat perception (HBP) task to measure interoceptive accuracy, and the Rubber Hand Illusion (RHI) to measure malleability of body ownership. Based on prior findings, we hypothesized that the less accurate you are at counting your heartbeats, the more susceptible you will be to the RHI (i.e. the more malleable your sense of body ownership will be). In addition, we were also interested in exploring the relationship between interoception and emotion recognition ability (ERA). In this experiment, we failed to induce the RHI, and thus could not investigate the relationship between endogenous and exogenous body-related information. However, we successfully demonstrated the reliability of the interoceptive accuracy HBP task, as well as demonstrated that interoceptive accuracy is not related to ERA.

abstract: Thesis

abstract: Master of Science (MSc)


title: Performance of EHD assisted convective boiling heat exchangers utilizing dielectric fluids

contributor:
Cotton, James
Mechanical Engineering

subject: Convective Boiling, electrohydrodynamics, control, dielectric, EHD, two phase, refrigerant, heat exchanger

abstract:
Electrohydrodynamics in convective boiling heat exchangers has been studied since the early 1990’s and has been shown to result in a large variation in the average performance enhancement of these systems. The behaviour of EHD assisted convective boiling heat exchangers, is still largely unpredictable owing to a number of conflicting parameters which are rarely kept constant in empirical studies, i.e. flow pattern and heat flux. In this thesis, it is hypothesised that by reducing the number of confounding variables in the experimental test conditions, and understanding the behaviour of EHD in convective boiling systems from a flow pattern dependent point of view, this can allow for the development of flow pattern dependent experimental correlations & numerical models to develop a methodology for performance prediction, control strategies and system integration for an EHD assisted convective boiling heat exchange device.
A 30 cm long, smooth, concentric, annular test section is used to analyse the effect of EHD on convective boiling performance under constant flow pattern, constant, low heat flux, and negligible free charge conditions. Saturated boiling conditions for flow-rates between 60 kg/m2s and 180 kg/m2s and thermodynamic quality range of 0.25 - 0.55 were tested. Heat transfer enhancement ranged from 0.95 to 2.3 fold and pressure drop penalty varied from 1.4-3 fold over these test conditions. The local EHD behaviour was found to be more consistent along the axial length of the test section compared to empirical data in the literature, which uses much longer test section lengths, where flow pattern can vary. An experimental database of EHD convective boiling data for horizontal annular electrode geometries was compiled to be used for analysis purposes. The performance of the heat exchanger in both free-field and high voltage conditions could be explained by looking at the flow patterns in each case.
Electrostatic modelling was used to determine electric field strength distributions and interfacial stress due to the dielectrophoretic and electrostriction forces on the liquid vapour interface, which induce liquid extraction based flow pattern re-distribution in two phase dielectric flows. A fully coupled 2D, adiabatic numerical model for the effect of the electric body force on two phase flow pattern distribution was developed. Charge was neglected in this model. Two different models for the interface migration were used and compared; a moving mesh (MM) interface tracking model and a volume of fluid (VOF) interface tracking mode. Both were verified against published experimental data. For the liquid extraction verification case, the VOF model suffers interface stretching up to 300% resulting in a 42% slower extraction time and underestimated forces. However, it is useful to use the VOF model when simulating complex flow patterns which are subject to topological changes like bubble detachment or droplet coalescence as these cannot be simulated with the moving mesh model. The moving mesh model can be used to determine the error in forces and phase velocities when using the VOF model.
A methodology for generating two-phase EHD flow pattern maps was developed by incorporating the electric Froude number into each of the flow pattern transition equations. A semi-analytical model was developed to determine the maximum interfacial stress due to EHD for stratified flows to reduce the requirement of numerical modeling, and thus the flow pattern map generation methodology is fully equation based. Although transition equations developed by multiple researchers were used and compared, it is recommended that the Steiner transitions equations be used for EHD two-phase flow pattern mapping, until more fundamental experimental data can be gathered to modify the semi-empirical transition equations used in more state-of-the-art maps. EHD was found to significantly affect the “stratified-stratified wavy (SSW)” and “stratified wavy – intermittent/annular (SWIA)” transitions for concentric horizontal geometries, with minimal effect on the transition to dryout and no effect on the “intermittent dispersed bubbly (IB)” transition. The EHD flow pattern maps were generated and compared against data from the present study and a database of experimental EHD convective boiling studies. The regions where maximum enhancement were seen in the literature correlate well with those regions predicted by the maps.
Performance correlations for the EHD convective boiling heat transfer and pressure drop were developed. They are based on the free-field Kandlikar correlation [1] for two-phase heat transfer and the Chisholm-Laird [2] correlations for two-phase pressure drop, respectively. The EHD flow pattern map is used to determine what the flow pattern for a given applied voltage will be, and flow pattern based enhancement linear multipliers are then used to determine the EHD performance above the free-field case.
EHD is a form of active enhancement, i.e. it requires power. Thus, it would be used in systems that require performance control or regulation, in addition to some niche applications like space where it can be used instead of gravity. A method for EHD controller design was established and an EHD control algorithm was designed and implemented on the test section for the flow pattern and applied waveforms that were determined to be optimal to maximize enhancement in this geometry. System identification was performed empirically to determine the transfer function between EHD voltage and heat load to be controlled for. This resulted in a 1st order plus dead-time model to which proportional-integral controller constants were tuned. Two controllers were developed; a PID control system and a Smith model predictive control system and these were compared based on their ability to regulate the output quality of the heat exchanger when subject to dynamic heat loading. Regulation was achieved for a dynamic heat load within ±25% bound from the designed steady state load. These controllers operate on one flow pattern as the test section is 30 cm long. Flow pattern dependent controller design would be required for a full length convective boiling heat exchanger.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Control of boiling heat transfer using electric fields is hard to predict. This thesis presents a set a design guidelines based on how the electric field enhances the flow pattern.


title: Active Sensor for Microwave Tissue Imaging with Bias-Switched Arrays

contributor:
Nikolova, Natalia K.
Bandler, John W.
Electrical and Computer Engineering

subject:
microwave imaging
bias-switched
breast cancer
antenna array

abstract:
A prototype of a bias-switched active sensor is developed and measured to establish the achievable dynamic range in a new generation of active arrays for microwave tissue imaging.
The sensor integrates a printed slot antenna, a low-noise amplifier (LNA) and an active mixer in a single unit, which enables inter-sensor separation distance as small as 12 mm.
The sensor's input covers the bandwidth from 3 GHz to 7.5 GHz.
Its output intermediate frequency (IF) is 30 MHz.
The sensor is controlled by a simple bias-switching circuit, which switches ON and OFF the bias of the LNA and the mixer simultaneously.
It is demonstrated experimentally that the dynamic range of the sensor, as determined by its ON and OFF states, is 109 dB and 118 dB at resolution bandwidths of 1 kHz and 100 Hz, respectively.

The integration of an LNA on the same board with each antenna element is also studied.
The LNA circuit dimensions have been reduced from 18.2 mm by 44.6 mm (the size of the evaluation board) to 6 mm by 8 mm in width and length, respectively.
Simulations show promising results.
Thus, fabrication and measurements can be carried out in the near future.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: THE IMPACT OF A POST-DELIVERY SLEEP PROTECTION INTERVENTION ON POSTPARTUM MATERNAL MENTAL HEALTH

contributor:
Frey, Benicio
Neuroscience

subject:
postpartum
maternal
sleep quality
sleep intervention

abstract:
INTRODUCTION: Poor sleep quality is a significant risk factor for the development of postpartum depression. This thesis examined the impact of a post-delivery intervention which promoted and protected sleep during the immediate postpartum period on maternal mood, sleep quality, and anxiety.
METHODS: 41 women with lifetime or current mood and/or anxiety disorders (12 receiving the intervention) were enrolled in this prospective naturalistic cohort study from the third trimester of pregnancy until 24 weeks postpartum. Depression, the primary outcome, was measured using the Edinburgh Postnatal Depression Scale at 12 weeks postpartum. Remaining outcomes (sleep quality and anxiety) were measured using self-report questionnaires (Insomnia Severity Index and State-Trait Anxiety Inventory, respectfully), and objective measures (i.e., actigraphy for sleep quality).
RESULTS: There were no significant differences between the comparison and intervention group in depressive symptomatology at postpartum week 12 (primary outcome). On our secondary outcomes, we found that there were no significant differences in subjective and objective sleep quality at postpartum week two, or anxiety symptomatology at postpartum week eight between the two groups. There were also no significant differences in breastfeeding rates between the two groups at postpartum week 24.
CONCLUSION AND FUTURE DIRECTIONS: Floor effects, specialized perinatal psychiatric treatment for a specific population, and low statistical power offer explanations for the observed null results. Strengths of our study include diagnosis of mood/anxiety disorders using the gold-standard (i.e., clinician diagnosis), and use of objective sleep measures. Future studies may benefit from implementing this intervention in resource-poor settings, using adequately powered research designs.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: While the arrival of a child is a celebrated and joyous occasion, it can also be a source of duress and anguish, particularly for the mother. Postpartum depression is a mood disorder experienced by 10-15% of mothers after childbirth. One of the strongest risk factors for the development of postpartum depression is disrupted postpartum sleep quality. This thesis examined the impact of an intervention designed to protect and promote sleep of mothers during the postpartum period in an effort to improve mood, sleep quality, and anxiety symptomatology. By improving maternal mental health, not only do women benefit, but their children, their partners, and the healthcare system.


title: NIR Imaging and its Application to Wheat Grading

subject:
NIR
NIR image
wheat
wheat grading

abstract:
Two topics related to near infrared (NIR) imaging technology are studied in this thesis. The first is on the calibration of line-scan NIR imaging systems, the second covers the feasibility of applying the NIR imaging technology for wheat grading. In the first study, a methodology is proposed to pretreat the NIR image data acquired by the line-scan NIR imaging system used in this thesis to reduce the systematic noise introduced by the imaging system. This calibration in a standardization methodology is shown to improve the result of multivariate image analysis (MIA) based on multi-way principal component analysis (MPCA). This method represents a practical
and easily used tool for calibration of line-scan NIR imaging systems in that it does not employ expensive standard reflectance material. In the second study, two projects are accomplished. In the first project, NIR imaging is used to classify different classes of wheat kernels. Multivariate statistical algorithms, soft independent modeling of class analogy (SIMCA) and partial least square discriminant analysis (PLS-DA) are used to discriminate between different types of wheat kernels using spectral features from NIR images. A new strategy of implementing multiclass PLS-DA algorithm is proposed in this part. The results from this study show that NIR imaging provides a potentially fast and objective method for qualitatively evaluating certain characteristics of wheat samples, such as fungal infection, sprout damage and foreign types of grain, which are now graded manually in wheat industry. In the second project, NIR imaging is used to predict the "falling number" (FN) of wheat samples. Three models are built between the features extracted from NIR images of the wheat kernels and the falling number measurements made on bulk samples. One uses a regular PLS algorithm, one uses the orthogonal partial least square (O-PLS) algorithm and the other uses the PLS plus canonical correlation analysis (PLS+CCA) algorithm. The models are analyzed and the performance of the algorithms is discussed. The errors in the prediction of the O-PLS model are investigated. The results from this study indicate that NIR imaging is a promising method for the rapid assessment of the FN of wheat samples.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Size Exclusion Chromatography of Poly (2-Methacryloyloxyethyl Phosphorylcholine) and its Interactions with Various Salts

title: Size Exclusion Chromatography of PMPC and its Interaction with Salts

contributor:
Zhu, Shiping
Chemical Engineering

subject:
exclusion
chromatography
salt
size exclusion

abstract:
My current thesis is regarding the application of Gel Permeation Chromatography (GPC) equipment and principles to the study of polyelectrolyte configuration in solution. The main focus of this study is the effect of salt on the hydrodynamic volume/solution properties of polyelectrolytes and the ability of GPC to effectively determine the degree of variation. This involves the comparison of different salt types and concentrations in aqueous solution. The specific polyelectrolyte examined is poly (2-methacryloyloxyethyl phosphorylcholine) (PMPC), a zwitterionic polymer (i.e. one having both positive and negative charges on the monomer). PMPC is a fairly new and promising polyelectrolyte for use in protein drug delivery and biomaterial surface applications. Understanding the effects of salt on this polyelectrolyte will aid in the development of technologies involving this polymer as well as other zwitterionic polymers. Different salts were utilized to formulate an effect of salt ions so that a systematic analysis could be performed. Using a control as reference it was determined that the salt does have an effect on the solution properties of the polyelectrolytes, as expected. The specific
properties examined were characterized into two categories; solution properties and ion properties. Solution properties involved the investigation of salt concentration, solution ionic strength and solution pH effects. For ion properties, salts were selected on the basis of ion charge, charge type and ion size, so that the effects of both the cation and anion components could be analyzed. Two parameters, namely, ion size/type and ion valency were examined for both the cation and the anion. In addition the configuration of the anion was also investigated. vSpecific conclusions found in this study were as follows:
1) The salt concentration has an effect up to a certain "saturation" point.
2) The ionic strength has no visible effect (any effect is related to the concentration
component).
3) There is no observable solution pH effect.
4) There is no observable cation effect. This includes no cation type/size or cation
valency effect.
5) There is a significant anion effect.
6) A smaller anion has a greater effect than a larger anion.
7) A divalent anion has a greater effect than a monovalent anion.
8) A monatomic anion has a greater effect than a polyatomic anion.
It was found that the effect of ion properties is related to mechanisms associated with the geometry of the polyelectrolyte. The negative charge group of the polyelectrolyte which is situated closer to the backbone (inside) is less important to the change in hydrodynamic volume resulting from ionic interactions with the salts since it is shielded by the positive charge group situated at the end of the side chain (outside). The observed phenomena were also explained by other chemical and physical properties such as charge density and ionic potential. In addition to the original plan of study, other phenomena were observed and later explained, such as the presence of four distinct regions associated with salt concentration and the variation m the degree of hydrodynamic volume change with different molecular weight samples. The application of aqueous GPC equipment (including a differential refractive index detector (DRI)) and principles to the study of polyelectrolyte solution effects minimizes the detection equipment required and, provides sufficient resolution and accuracy for examination of solution properties while remaining time and cost effective. The project discoveries have shown that size exclusion chromatography provides an excellent means of obtaining a complete and accurate set of correlations between polyelectrolyte charge and salt effects.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: A Novel Use of Confocal Microscopy to Study Lysozyme Sorption to Silicone Hydrogel and Conventional Hydrogel Contact Lens Materials

contributor:
Sheardown, Heather
Jones, Lyndon
Chemical Engineering

subject:
confocal microscopy
microscopy
lysozyme sorption
lysozyme
contact lens
hydrogel contact lens
silicone hydrogel

abstract:
The purpose of this study was to observe penetration profiles of lysozyme on a variety of contact lens materials by confocal microscopy, to analyze influential factors that are involved in these penetration curves and to suggest possible mechanisms related to the in-eye clinical performance of these materials. An FITC-lysozyme conjugate was synthesized in-house by amine reaction. Contact lenses were incubated in a lysozyme solution with a final concentration of 1.9 mg/mL for various periods before undergoing microscopic analysis. Optimal parameters for confocal scanning were successfully obtained to acquire desired fluorescence signals on various contact lenses. Measurement units were converted into absolute amounts of lysozyme using lysozyme data from ^(125)I gamma counting studies. A rhodamine labeled dextran solution was applied to distingush the surface of the contact lenses under examination. The data from these studies were then used to calculate the theoretical numbers of layers of adsorbed lysozyme on the lens surface. The results show that there were distinct differences in lysozyme penetration in the twelve hydrogel materials examined. A pure pHEMA lens, with a water content of 38%, deposited lysozyme primarily on the lens surface after 24 hours, with full penetration occurring after 4-weeks of incubation. Three types of non-ionic contact lens materials with water contents > 50% exibited rapid penetration within the lens bulk after 24-hours incubation, with increased deposition within the matrix after 4 weeks. Two ionic, high water content polymers (Acuvue 2 and Focus Monthly) exhibited markedly different penetration profiles, particularly after 24 hours, with very rapid and total penetration in Acuvue 2, as compared with partial penetration in Focus Monthly. Modern silicone hydrogel contact lenses can be nominally divided into first generation, plasma-modified materials and second generation materials which incorporate an internal wetting agent such as polyvinyl pyrrolidone (PVP). These materials exhibited different lysozyme deposition profiles. Lysozyme fully penetrated PureVision after 24 hours, whereas no lysozyme penetration occurred on lenses manufactured from Focus Night & Day or O_2Optix, even after 4 weeks. Lenses manufactured from Acuvue Advance and Acuvue OASYS, two second generation silicone hydrogel lenses, also displayed their own characteristic deposition profile. Acuvue Advance always exhibited a partial penetration of lysozyme within the
matrix, even after 4 weeks of doping. Interestingly, Acuvue OASYS showed a similar profile to Focus Night & Day and O_2Optix, with predominantly surface deposition occurring. To confirm possible surface adsorption of lysozyme on surface-coated Focus Night & Day and O_2Optix, a rigid polymethylmethacrylate (PMMA) contact lens was used as a model of surface adsorption. A mounting medium containing rhodamine labeled dextran was scanned to distinguish the lens surface, as it was assumed that no surface penetration of the very high molecular weight dextran would occur. Using this model, it was confirmed that surface adsorption of lysozyme occurred on these plasmacoated lens materials, which is similar to that seen with PMMA. In a further experiment, it was seen that lysozyme sorption on Acuvue OASYS exhibits a penetration profile which is different to that seen in Focus Night & Day and O_2Optix, with lysozyme just penetrating the lens surface. The results from the studies described above demonstrated that in 24 hours lysozyme sorption did not achieve a complete monolayer. However, after 4 weeks multi-layer adsorption occurred, with the more hydrophilic materials depositing
the most lysozyme. The quantitative measurement of lysozyme penetration on and into contact lens materials by confocal microscopy combined with ^(125)I labelling offers a valuable tool to discover the potential mechanisms of interactions between protein and polymer materials. This study reveals some important information that may be beneficial to contact lens development and will prove to be valuable in other more broad areas of biomedical research in which polymers and biological fluids come into contact.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Demographic Transparency to Combat Discriminatory Data Analytics Recommendations

contributor:
Hassanein, Khaled
Business

subject:
Data Analytics
Discrimination
Demographic Transparency
Ethical Decision Making
Moral Intensity
Proximity

abstract: Data Analytics (DA) has been blamed for contributing to discriminatory managerial decisions in organizations. To date, most studies have focused on the technical antecedents of such discriminations. As a result, little is known about how to ameliorate the problem by focusing on the human aspects of decision making when using DA in organizational settings. This study represents an effort to address this gap. Drawing on the cognitive elaboration model of ethical decision-making, construal level theory, and the literature on moral intensity, this study investigates how the availability and the design of demographic transparency (a form of decisional guidance) can lower DA users’ likelihood of agreement with discriminatory recommendations of DA tools. In addition, this study examines the role of user’s mindfulness and organizational ethical culture on this process. In an experimental study users interact with a DA tool that provides them with a discriminatory recommendation. The results confirm that demographic transparency significantly impacts both recognition of the moral issue at hand and perceived proximity toward the subject of the decision, which in turn help decrease the likelihood of users’ approval of the discriminatory recommendation. Moreover, the results suggest that user’s mindfulness and organizational ethical culture enhance the positive impacts of demographic transparency.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)


title: Surface Modification of Metals through Atom Transfer Radical Polymerization Grafting of Acrylics

title: Surface Modification of Metals Through ATRP Grafting of Acrylics

subject:
metal
modification
ATRP
acrylic
atom transfer radical polymerization
polymerization
atom transfer

abstract: In this thesis, acrylic polymers (methyl methacrylate, MMA; N,N' -dimethylamino ethyl methacrylate, DMAEMA; oligo-ethylene glycol methacrylate, OEGMA; trifluoroethyl methacrylate, TFEMA) were grafted from various metal surfaces such as cold rolled steel (CRS), stainless steel (SS), aluminum (Al) and nickel (Ni) through surface-initiated atom transfer radical polymerization (s-ATRP). The purpose is to improve corrosion resistance and to introduce multi-functionality to metal surface. The metal substrates were precisely polished and were facile for characterization by ellipsometry. 3-((alpha)-Bromo-2-methyl) propylamide propyltriethoxysilane was synthesized and immobilized on the metal surfaces under a simple and workplace-friendly condition. Grafting density was estimated to be 0.58 chains/nm^2 for CRS-gPMMA, 0.55 chains/nm^2 for Ni-g-PMMA and 0.18 chains/nm^2 for SS-g-DMAEMA and 0.66 chains/nm^2 for SS-g-PDMAEMA. Two strategies, i.e., "adding free initiator" and "adding deactivator", were adopted for the control over polymer molecular weight and grafting density in the CRS-g-PMMA system. The polymer thicknesses up to 80 nm were obtained within 80 min using the "adding deactivator" strategy. Copper and iron catalyst systems were compared on different metal substrates. A severe deactivation of copper catalyst was observed on the metal substrates. Controlled polymerization with relatively low polydispersity was obtained using the iron catalyst. The metal surfaces at various stages of modification were characterized by X-ray photoelectron spectroscopy, ellipsometry, goniometry, and atomic force microscopy (AFM). Electrochemical experiments were also carried out to measure the polarization resistance and corrosion potential of CRS-g-PMMA substrates. This thesis work demonstrated that the surface-initiated ATRP is a versatile means for the surface modification of metals with well-defined and functionalized polymer brushes.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: REPEATED TIP-OF-THE-TONGUE STATES: A CLOSER LOOK AT THE ERROR REPETITION EFFECT

contributor:
Humphreys, Karin R.
Psychology

subject: Cognition Psycholinguistics

abstract: There are some disagreements surrounding what constitutes a tip-of-the-tongue (TOT) state. The most widely accepted hypothesis to account for TOT states is the Transmission Deficit Hypothesis, which suggests TOT states are the result of a phonological access failure (Burke, Mackay, Worthley, & Wade, 1991). The TOT state is largely hypothesized to be a general subthreshold state, which suggests that the TOT state does not have a specific underlying mechanism. A relatively new line of inquiry involves that of repeated TOT states. As a theoretical extension to the phonological failure account of TOT states, Warriner and Humphreys (2008) found that TOT states repeat at a rate greater than would be predicted by chance, which has been termed the error repetition effect. They argue that the mechanism underlying the error repetition effect is a Hebbian-like error learning mechanism, suggesting that the TOT state is not a general state, but rather a specific state. D’Angelo & Humphreys (2015) did an extensive study that provided evidence for the validity of the error repetition effect. This dissertation explores additional features of the TOT state that had not been previously tested. The first study explored what is being learned during a TOT state. Specific phonological information was found to repeat along with repeated TOT states, supporting the phonological failure hypothesis. Second, this dissertation includes the first study to determine if older adults experience the error repetition effect using Warriner and Humphreys’ (2008) methodology. The evidence suggests that repeated TOT states are a part of normal aging rather than pathological cognitive dysfunction. Third, metacognition researchers argue that the TOT state is a subjective experience caused by a mechanism that assesses the likelihood of recall from memory. The third study demonstrates evidence contrary to the metacognitive account, which further supports the phonological failure account of TOT states.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)

abstract: A tip-of-the-tongue (TOT) state is the feeling of knowing a word, but being unable to produce the sounds to articulate the word. A TOT state is often accompanied by a feeling of frustration. For example, a TOT state may occur when one encounters a colleague at work. One may remember the first letter of the colleague’s name, and the name may feel like it is figuratively within reach, but the full name cannot escape the speaker’s lips. Perhaps even more frustrating is the occurrence of a TOT state time after time for a specific word. This dissertation explores the tendency for TOT states to recur. The results point towards the hypothesis that repeated TOT states are the result of a specific breakdown in the portion of the word production system that connects syntactic units to phonological units.


title: Dynamic Reoptimization and Control Under Shutdown Conditions

contributor:
Swartz, Christopher
Chemical Engineering

subject:
reoptimization
shutdown
shutdown condition
control

abstract: A systematic control strategy is proposed for optimal operation of plants containing integrated process units in the event of unit shutdowns or failures. This entails manipulating the degrees-of-freedom available during and after a shutdown in such a way that production is restored in a cost-optimal fashion while meeting all safety and operational constraints. In this work, we investigate the problem of coordinating various buffer tanks and recycle streams during the period of transition to minimize production losses. The problem is cast in a dynamic optimization framework. The case studies in our work are based on a simulation of a Kraft pulp mill where a process unit is shut down and taken off-line for a period of time, and is subsequently restored. Based on an estimate of the downtime, our proposed control system then computes and implements a set of optimal control trajectories that accommodates the shutdown. This work extends prior studies ([8], [24]) by considering in addition two key issues -inclusion of feedback mechanisms to counter uncertainty, and the development of a software-based modeling tool. The downtime estimate is a crucial parameter for performing the control calculations. This estimate will usually be based on past operational experience or on direct information about the prognosis of the shutdown. In practice, this estimate will not correspond exactly to the actual downtime; thus we consider re-optimization based on revised downtime estimates. The remainder of the trajectory is re-optimized from the current state of the system, and the controller performs what is essentially a mid-course correction. This feedback approach has considerable advantages over a multi-scenario optimization approach for dealing with uncertainty in the estimated downtime, in that the resulting control trajectories are less conservative. The performance of this re-optimization scheme is studied in this work under various failure scenarios. Uncertainty also exists due to model imperfections and unmeasured disturbances. We therefore account for this uncertainty by considering the trajectory optimization problem within an integrated nonlinear predictive control framework. The type of operation under consideration (response to partial shutdown conditions) is inherently unsteady in nature, and the control horizon as measured from the onset of the failure is fixed. Among the distinctive features of the controller are: a shrinking prediction horizon, an economics-driven objective function and the use of a nonlinear differential-algebraic equation-based model. The controller is also "event-cognizant" in the sense that explicitly known future events such as shutdowns and startups can be specified and accommodated within the prediction algorithm. Case studies demonstrating the performance of the overall feedback strategy are presented. In the course of this work, we developed a specialized software-based modeling tool that simplifies the tasks of representing, discretizing, and solving dynamic optimization problems. The main component of this tool is a domain-specific language named MLDO (Modeling Language for Dynamic Optimization). This tool is tailored to the representation of constructs specific to the dynamic optimization problem domain. Models written in MLDO are used as a precursors for generating intermediate AMPL-based models (discretized using an implicit Runge-Kutta method), which are subsequently solved using a large-scale nonlinear optimizer, IPOPT.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Graph-Based Solution for Two Scalar Quantization Problems in Network Systems

contributor:
Dumitrescu, Sorina
Electrical and Computer Engineering

subject:
Wyner-Ziv coding
Multiple Description Coding

abstract:
This thesis addresses the optimal scalar quantizer design for two problems, i.e. the two-stage Wyner-Ziv coding problem and the multiple description coding problem for finite-alphabet sources.
The optimization problems are formulated as the minimization of a weighted sum of distortions and rates. The proposed solutions are globally optimal when the cells in each partition are contiguous.
The solution algorithms are both based on solving the single-source or the all-pairs minimum-weight path (MWP) problems in certain weighted directed acyclic graphs (WDAG). When the conventional dynamic programming technique is used to solve the underlying MWP problems the time complexity achieved is $O(N^3)$ for both problems, where $N$ is the size of the source alphabet.

We first present the optimal design of a two-stage Wyner-Ziv scalar quantizer with forwardly
or reversely degraded side information (SI) {for finite-alphabet sources and SI}. We assume that binning is performed optimally and address the design of the quantizer partitions.
A solution based on dynamic programming is proposed with $O(N^3)$ time complexity.
%The solution relies on finding the single-source or the all-pairs MWP in several one dimensional WDAGs.
Further, a so-called {\it partial Monge
property} is additionally introduced and a faster solution algorithm exploiting this property is proposed. Experimental results assess the practical performance of the proposed scheme.

Then we present the optimal design of an improved modified multiple-description scalar quantizer (MMDSQ).
The improvement is achieved by optimizing
all the scalar quantizers.
%are optimized under the assumption that all the central and side quantizers have contiguous codecells.
The optimization is based on solving the single-source MWP problem in a coupled quantizer graph and the all-pairs MWP problem in a WDAG. Another variant design with the same optimization but enhanced with a better decoding process is also presented to decrease the gap to theoretical bounds. Both designs for the second problem have close or even better performances than the literature as shown in experiments.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: EOSINOPHIL/BASOPHIL PROGENITORS: A POSSIBLE ROLE IN THE PATHOGENESIS OF ATOPIC DERMATITIS

contributor: Medical Sciences (Division of Physiology/Pharmacology)

subject: Immunology, Dermatology, Atopic Dermatitis, Eczema, Allergy, Eosinophil, Basophil, Eosinophil/Basophil Progenitor,

abstract: Atopic dermatitis (AD) is a common skin disease that is characterized by chronic, relapsing skin inflammation and eczematous, itchy lesions. In AD, systemic and local eosinophilia and basophilia is thought to contribute to disease progression in both acute and chronic lesions. It has been previously shown that in chronic allergic inflammatory diseases, tissue eosinophilia and basophilia may in part result from eosinophil/basophil (Eo/B) progenitors trafficking from the bone marrow and maturing in tissue in response to type 2 cytokines including IL-5 and IL-3. We therefore proposed that a similar mechanism could be contributing to the pathogenesis of AD. First, we compared lesional and non-lesional AD tissue, and found approximately 10-fold higher levels of Eo/B progenitors in the lesional tissue (p<0.05). As previous research has shown an increase in Eo/B progenitors in the airways of allergic asthmatics post inhaled allergen challenge, we next examined whether Eo/B progenitors increased locally in the acute phase of AD using the intradermal allergen challenge model. Compared to intradermal diluent challenge there was an increase in Eo/B progenitors (5.5-fold), eosinophils (18-fold) and basophils (2.5-fold) 24 hours post intradermal allergen challenge (all p<0.05). These increases were consistent with findings in allergic airways. Lastly, we examined the relationship between disease severity and Eo/B progenitors in inflamed lesional (chronic) and allergen-challenged (acute) tissue. We found that Eo/B progenitors in lesional tissue positively correlated with disease severity (EASI R=0.71, p<0.05 and SCORAD R=0.65, p<0.05), while in allergen-challenged tissue a trend was seen for a positive correlation between Eo/B progenitors and disease severity (EASI R=0.48, p=0.07 and SCORAD R=0.46, p=0.09). These results highlight the potential involvement of Eo/B progenitors in the disease pathogenesis of AD.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: Atopic dermatitis is a common skin disease that is characterized by chronic, relapsing skin inflammation and eczematous, itchy lesions. In other allergic diseases, a cell called the “eosinophil/basophil progenitor” contributes to the accumulation of inflammatory cells in the diseased organ. We proposed that eosinophil/basophil progenitors found in the skin may be contributing to the development of local allergic inflammation. In patients with moderate-to-severe atopic dermatitis we compared acute responses to intradermal allergen and chronic skin lesions to diluent-challenged and un-affected skin, respectively. Allergen-challenged skin had more eosinophil/basophil progenitors, mature eosinophils and basophils 24 hours’ post-challenge compared to unchallenged skin (p<0.05). Chronic skin lesions had more eosinophil/basophil progenitors than un-affected skin (p<0.05). The number of eosinophil/basophil progenitors positively correlated to disease severity as determined by EASI and SCORAD. Our results suggest that accumulation of eosinophil/basophil progenitors in skin of atopic dermatitis patients could support allergic inflammation and contribute to disease severity.


title: Flow-Sound-Structure Interaction in Spring-Loaded Valves

contributor:
Ziada, Samir
Hassan, Marwan
Mechanical Engineering

subject:
flow-induced vibration
flow-sound-structure interaction
fluid-structure interaction
valve vibrations
spring-loaded valves
compressor valves
pipe acoustics
wear
experimental
numerical
modelling
theoretical

abstract:
This thesis provides a comprehensive investigation of flow-sound-structure coupling in spring-loaded valves subjected to air flow. While they are commonly used in a multitude of applications, these types of valves have been found to experience severe vibrations when interaction is present among the structure, the hydrodynamic field, and the acoustic field for a range of operational valve structural characteristics, flow parameters, and connected piping length.

The first part of this investigation was aimed at characterizing experimentally the valve’s dynamic behaviour and the parameters affecting the onset of self-excited instability. The occurrence of instability was mainly driven by the presence of acoustic feedback: the connected length of piping had to be sufficiently long, with a longer pipe correlating to more severe vibrations. In addition, it was found that the valve’s oscillation frequency depends on the modal characteristics of the combined valve piping system, rather than the structural natural frequency alone. Furthermore, an increase in the valve’s spring stiffness caused the vibrations to become more severe. Meanwhile, other parameters such as initial spring preload force and valve plate area only had moderate effects on the stability behaviour of the valve.

The second part of the investigation sought to develop a theoretical model that could simulate the valve’s response when subjected to air flow while considering the effects of acoustic feedback and impact on the seat and limiter. Thus, a structural model of the valve was developed based on a single-degree-of-freedom model of the system with impact computed based on a pseudo-force method. The hydrodynamic field relied on a one dimensional unsteady Bernoulli description of the flow. Finally, the acoustic interaction was accounted for using the one-dimensional wave equation resolved using a finite difference scheme. The model has demonstrated remarkable agreement with the experimental results. It has shown an ability to predict the modal characteristics of the system as well as correctly predict the effect of increased stiffness or increased piping length on vibration amplitude.

The final part of the investigation consisted in designing countermeasures to mitigate the effects of this self-excited instability mechanism. A concentric Helmholtz-type cavity resonator, an orifice plate, and an anechoic termination are placed at the downstream side of a model valve which were seen to be unstable in the experimental and modelling phases of the investigation. All tested devices were able to eliminate the self excited instability mechanism. The applicability and robustness of each of these methods were discussed.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)