Graduate Theses & Dissertations

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Stability Properties of Disease Models under Economic Expectations
Comprehending the dynamics of infectious diseases is very important in formulating public health policies to tackling their prevalence. Mathematical epidemiology (ME) has played a very vital role in achieving the above. Nevertheless, classical mathematical epidemiological models do not explicitly model the behavioural responses of individuals in the presence of prevalence of these diseases. Economic epidemiology (EE) as a field has stepped in to fill this gap by integrating economic and mathematical concepts within one framework. This thesis investigated two issues in this area. The methods employed are the standard linear analysis of stability of dynamical systems and numerical simulation. Below are the investigations and the findings of this thesis: Firstly, an investigation into the stability properties of the equilibria of EE models is carried out. We investigated the stability properties of modified EE systems studied by Aadland et al. [6] by introducing a parametric quadratic utility function into the model, thus making it possible to model the maximum number of contacts made by rational individuals to be determined by a parameter. This parameter in particular influences the level of utility of rational individuals. We have shown that if rational individuals have a range of possible contacts to choose from, with the maximum of the number of contacts allowable for these individuals being dependent on a parameter, the variation in this parameter tends to affect the stability properties of the system. We also showed that under the assumption of permanent recovery for disease coupled with individuals observing or not observing their immunity, death and birth rates can affect the stability of the system. These parameters also have effect on the dynamics of the EE SIS system. Secondly, an EE model of syphilis infectivity among &ldquo men who have sex with men &rdquo (MSM) in detention centres is developed in an attempt at looking at the effect of behavioural responses on the disease dynamics among MSM. This was done by explicitly incorporating the interplay of the biology of the disease and the behaviour of the inmates. We investigated the stability properties of the system under rational expectations where we showed that: (1) Behavioural responses to the prevalence of the disease affect the stability of the system. Therefore, public health policies have the tendency of putting the system on indeterminate paths if rational MSM have complete knowledge of the laws governing the motion of the disease states as well as a complete understanding on how others behave in the system when faced with risk-benefit trade-offs. (2) The prevalence of the disease in the long run is influenced by incentives that drive the utility of the MSM inmates. (3) The interplay between the dynamics of the biology of the disease and the behavioural responses of rational MSM tends to put the system at equilibrium quickly as compared to its counterpart (that is when the system is solely dependent on the biology of the disease) when subjected to small perturbation. Author Keywords: economic and mathematical epidemiology models, explosive path, indeterminate-path stability, numerical solution, health gap, saddle-path stability, syphilis,
TESTING THE ROLE OF BIMODAL CELLS IN NEAR-HAND EFFECTS
We investigated whether hand-proximity effects arise from the recruitment of visual-tactile bimodal cells. In Experiment 1, we executed right-hand open-loop reaching movements to targets, presented either near or far from the resting left-hand, and after applying repetitive transcranial magnetic stimulation (rTMS) to suppress neuronal activity in the PMd and AIP, in Experiment 2. Results from Experiment 1, indicated that near-hand targets improved accuracy and reduced variability. In Experiment 2, suppressing PMd showed similar near-hand effects as above. In contrast, applying rTMS to AIP disrupted the representation of target location, indicating less accuracy and greater error. Near-hand proximity effects possibly arise from the recruitment of visual-tactile bimodal cells within the human AIP. Author Keywords: anterior intraparietal sulcus, peripersonal space, repetitive transcranial magnetic stimulation (rTMS), , rTMS, anterior intraparietal sulcus, AIP., visual-tactile bimodal neurons
Self-Organizing Maps and Galaxy Evolution
Artificial Neural Networks (ANN) have been applied to many areas of research. These techniques use a series of object attributes and can be trained to recognize different classes of objects. The Self-Organizing Map (SOM) is an unsupervised machine learning technique which has been shown to be successful in the mapping of high-dimensional data into a 2D representation referred to as a map. These maps are easier to interpret and aid in the classification of data. In this work, the existing algorithms for the SOM have been extended to generate 3D maps. The higher dimensionality of the map provides for more information to be made available to the interpretation of classifications. The effectiveness of the implementation was verified using three separate standard datasets. Results from these investigations supported the expectation that a 3D SOM would result in a more effective classifier. The 3D SOM algorithm was then applied to an analysis of galaxy morphology classifications. It is postulated that the morphology of a galaxy relates directly to how it will evolve over time. In this work, the Spectral Energy Distribution (SED) will be used as a source for galaxy attributes. The SED data was extracted from the NASA Extragalactic Database (NED). The data was grouped into sample sets of matching frequencies and the 3D SOM application was applied as a morphological classifier. It was shown that the SOMs created were effective as an unsupervised machine learning technique to classify galaxies based solely on their SED. Morphological predictions for a number of galaxies were shown to be in agreement with classifications obtained from new observations in NED. Author Keywords: Galaxy Morphology, Multi-wavelength, parallel, Self-Organizing Maps
Near-Hand Effects and Recruitment of Visual-Tactile Bimodal Cells
Near-hand benefits are seen when individuals are able to process targets more quickly, accurately, and with greater precision when a hand is placed near, rather than far from a target. One possibility is that near-hand stimuli recruit visual-tactile bimodal cells. Research reports that placing a hand near a target delayed immediate saccade onset and speeded delayed saccade onset. Study 1 examined saccade onset to targets appearing near a real hand, a realistic fake hand, or a non-hand visual cue. Immediate saccades were facilitated and delayed saccades were slowed with a real hand in the display, in comparison to a fake hand and no-hand. To establish the link between near-hand effects and bimodal cells, Study 2 used repetitive transcranial magnetic stimulation (rTMS) to depress cortical activity in PMd. RTMS did not induce a reversal of interference induced by near-hand, congruent targets. However, a reversal of the hand effect was found in the stimulation group; a real hand in the display may delay immediate saccades and improve delayed saccades post-stimulation. This finding may double dissociate the effect of the real hand from the fake hand and may be inconsistent with the hypothesis that the hand is attracting attention. Author Keywords: multisensory integration, near-hand effects, PMd, premotor cortex, rTMS, visual-tactile bimodal neurons
An Investigation of the Impact of Big Data on Bioinformatics Software
As the generation of genetic data accelerates, Big Data has an increasing impact on the way bioinformatics software is used. The experiments become larger and more complex than originally envisioned by software designers. One way to deal with this problem is to use parallel computing. Using the program Structure as a case study, we investigate ways in which to counteract the challenges created by the growing datasets. We propose an OpenMP and an OpenMP-MPI hybrid parallelization of the MCMC steps, and analyse the performance in various scenarios. The results indicate that the parallelizations produce significant speedups over the serial version in all scenarios tested. This allows for using the available hardware more efficiently, by adapting the program to the parallel architecture. This is important because not only does it reduce the time required to perform existing analyses, but it also opens the door to new analyses, which were previously impractical. Author Keywords: Big Data, HPC, MCMC, parallelization, speedup, Structure
THE PROPENSITY TOWARD EXTREMIST MIND-SET AS PREDICTED BY PERSONALITY, MOTIVATION, AND SELF-CONSTRUAL
ABSTRACT The Propensity Toward Extremist Mind-Set as Predicted by Personality, Motivation, and Self-Construal Nick Fauset Multivariate regression analyses were used to determine the effects of Personality (Neuroticism, Extraversion, Openness, Agreeableness, and Conscientiousness), Motivation (External, Amotivation, Intrinsic, and Identified), and Self-Construal (Independent and Interdependent) on three domains of Extremist Mind-Set (Proviolence, Vile World, and Divine Power). Participants consisted of first year undergraduate students (209 females, 76 males) enrolled in Introductory Psychology (N=279) and/or Introductory Economics (N=7), whom participated for course credit. The Motivation measure was problematic for students to complete and this variable was dropped from the model due to missing data. Decreases in Neuroticism, Openness, Agreeableeness, and Interdependent were significantly correlated with increases in Proviolence. Decreases in Agreeableness were correlated with increases in Vile World. Decreases in Openness, and increases in Agreeableness and Interdependent were significantly correlated with increases in Divine Power. These observations provide an interesting perspective on the types of Canadian undergraduate students who are more likely to score highly on measures of Extremism. Keywords: Militant Extremist Mental Mind-Set, Extremism, Personality, Five Factor Model, Motivation, Intrinsic, Extrinsic, Self-Construal, Independent, Interdependent Author Keywords: Extremism, Militant Extremist Mental Mind-Set, Motivation, Personality, Self-Construal
Role of Multiple Nights of Sleep in the Consolidation of an Engaging and Complex Motor Learning Task
The present study examined the role of multiple nights of sleep in the consolidation of a complex motor learning task. Participants were 24 Trent undergraduates, 12 in the learning group (Mage = 20.33, SD = 1.87, 10 female) and 12 in the control group (Mage = 21.92, SD = 3.42, 7 female). Participants underwent 5 consecutive nights of polysomnographic recordings, with a Rock Band learning session on the third night. A series of 2(group)x4(night) ANOVAs were performed on the sleep variables. Interactions were found in the number of spindles detected at Pz, F(333) = 9.19, p <.01, and in the density of spindles detected at Pz, F(3,33) = 4.06, p <.05. The pattern of changes from baseline was significantly different between the two groups; spindles increased in the learning group and decreased in the control group. The novel finding was that spindle number/density remained elevated at the third post-learning night of sleep. Author Keywords: Motor Learning, Procedural Memory, Sleep, Sleep Spindles
Molecular Dynamics Simulations of Aqueous and Confined Systems Relevant to the Supercritical Water Cooled Nuclear Reactor
Supercritical water (SCW) is the intended heat transfer fluid and potential neutron moderator in the proposed GEN-IV Supercritical Water Cooled Reactor (SCWR). The oxidative environment poses challenges in choosing appropriate design materials, and the behaviour of SCW within crevices of the passivation layer is needed for developing a corrosion control strategy to minimize corrosion. Molecular Dynamics simulations have been employed to obtain diffusion coefficients, coordination number and surface density characteristics, of water and chloride in nanometer-spaced iron hydroxide surfaces. Diffusion models for hydrazine are evaluated along with hydration data. Results demonstrate that water is more likely to accumulate on the surface at low density conditions. The effect of confinement on the water structure diminishes as the gap size increases. The diffusion coefficient of chloride decreases with larger surface spacing. Clustering of water at the surface implies that the SCWR will be most susceptible to pitting corrosion and stress corrosion cracking. Author Keywords: Confinement, Diffusion, Hydration, MD Simulations, Supercritcal Water
Neonatal Environment Influences Behavioural and Physiological Reactivity to Stressors, and Mammary Gland Development in BALB/c Mice
Using rodent models, it is possible to study the behavioural and physiological outcomes of early life stress and the influences on normal mammary gland development and carcinogenic risk. Results demonstrate that the experience of three weeks of prolonged maternal separation (LMS; 4 hrs/day) increased the susceptibility of adult, but not pubertal, female BALB/c mice to engage in higher levels of depressive-related immobility behaviour and lower levels of active floating (a suggested adaptive coping behaviour) in the acute forced swim test, than offspring that experienced three weeks of brief separation (BMS; 15 min/day) events. Despite the increased immobility behaviour, adult LMS female offspring demonstrated lower basal corticosterone levels relative to BMS females. However, the experience of chronic early-life stress, regardless of the length, results in greater changes between non-stressed and stressed corticosterone levels (i.e. stressor reactivity) in adult females compared to their male counterparts. These changes were associated with decreased glucocorticoid receptor and coactivator-associated arginine methyltransferase 1 protein expression in mammary gland of female LMS mice at young adulthood, highlighting potential mechanisms underlying their heightened risk of mammary tumourigenesis. These data suggest that early life environments can induce behavioural and physiological alterations observed in adulthood, which may have an influence on the likelihood of malignancies developing in the breast. Author Keywords: coping, early life stress, mammary gland development, mother-infant interactions, steroid receptors, stressor reactivity
An Application of the Sinc-Collocation Method in Oceanography
In this thesis, we explore the application of the Sinc-Collocation method to an oceanography model. The model of interest describes a wind-driven current with depth-dependent eddy viscosity and is formulated in two different systems; a complex-velocity system and a real-value coupled system. In general, the Sinc-based methods excel over other traditional numerical methods due to their exponentially decaying errors, rapid convergence and handling problems in the presence of singularities at end-points. In addition, the Sinc-Collocation approach that we utilize exploits first derivative interpolation, whose integration is less sensitive to numerical errors. We present several model problems to demonstrate the accuracy, and stability of the method. We compare the approximate solutions determined by the Sinc-Collocation technique with exact solutions and also with those obtained by the Sinc-Galerkin approach in earlier studies. Our findings indicate that the method we utilized outperforms those used in past studies. Author Keywords: Boundary Value Problems, Eddy Viscosity, Oceanography, Sinc Numerical Methods, Wind-Driven Currents
Finger-Counting Habits and Number Processing in Canadian and Chinese University Students
In the past few years there has been increasing attention paid to the influence of the motor system on numerical cognition. A 2010 study by Domahs, Moeller, Huber, Willmes and Nuerk tested German and Chinese university students. Number processing time was influenced by cross cultural differences in finger counting habits This thesis replicated and elaborated on the aforementioned research design. This consisted of recruiting a sample of from a Chinese university and comparing them to a sample of Canadian university students. This study also compared within culture differences in participants' starting counting hand using additional SNARC analyses. A second experiment evaluated the possibility that asking participants about finger counting habits prior to the experiment may influence later answers. Cross cultural and within culture differences in finger counting habits influenced number processing. Participants also appeared to be more reliable reporters of their finger counting habits if asked at the end of the task rather than at the beginning. Author Keywords: Canadian, Chinese, Cross-cultural, Finger-counting, Magnitude, Number
ADAPT
This thesis focuses on the design of a modelling framework consisting of loose-coupling of a sequence of spatial and process models and procedures necessary to predict future flood events for the years 2030 and 2050 in Tabasco Mexico. Temperature and precipitation data from the Hadley Centers Coupled Model (HadCM3), for those future years were downscaled using the Statistical Downscaling Model (SDSM4.2.9). These data were then used along with a variety of digital spatial data and models (current land use, soil characteristics, surface elevation and rivers) to parameterize the Soil Water Assessment Tool (SWAT) model and predict flows. Flow data were then input into the Hydrological Engineering Centers-River Analysis System (HEC-RAS) model. This model mapped the areas that are expected to be flooded based on the predicted flow values. Results from this modelling sequence generate images of flood extents, which are then ported to an online tool (ADAPT) for display. The results of this thesis indicate that with current prediction of climate change the city of Villahermosa, Tabasco, Mexico, and the surrounding area will experience a substantial amount of flooding. Therefore there is a need for adaptation planning to begin immediately. Author Keywords: Adaptation Planning, Climate Change, Extreme Weather Events, Flood Planning, Simulation Modelling

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Format: 2024/03/28