Physical Sciences and Mathematics Commons^™

Bifurcation Of Limit Cycles In Smooth And Non-Smooth Dynamical Systems With Normal Form Computation, Yun Tian

Electronic Thesis and Dissertation Repository

This thesis contains two parts. In the first part, we investigate bifurcation of limit cycles around a singular point in planar cubic systems and quadratic switching systems. For planar cubic systems, we study cubic perturbations of a quadratic Hamiltonian system and obtain 10 small-amplitude limit cycles bifurcating from an elementary center, for which up to 5th-order Melnikov functions are used. Moreover, we prove the existence of 12 small-amplitude limit cycles around a singular point in a cubic system by computing focus values. For quadratic switching system, we develop a recursive algorithm for computing Lyapunov constants. With this efficient algorithm, we …

Application Of Risk Metrics For Role Mining, Sharmin Ahmed

Electronic Thesis and Dissertation Repository

Incorporating risk consideration in access control systems has recently become a popular research topic. Related to this is risk awareness which is needed to enable access control in an agile and dynamic way. While risk awareness is probably known for an established access control system, being aware of risk even before the access control system is defined can mean identification of users and permissions that are most likely to lead to dangerous or error-prone situations from an administration point of view. Having this information available during the role engineering phase allows data analysts and role engineers to highlight potentially risky …

The Development Of L-Tectonites In High-Strain Zone Settings: A Multiscale Modeling Investigation, Weiyin Chen

Electronic Thesis and Dissertation Repository

Shape fabrics in high-strain zones are commonly used to constrain deformation processes in the lithosphere. Linear fabric, as a type of shape fabric, usually indicates constrictional strain and is an important feature in orogenic belts. Among all kinds of linear fabrics, the isolated L-tectonites, which are surrounded by strong planar fabrics, are poorly understood. The isolated L-tectonites are generally developed in heterogeneous high-strain zones. Their formation involves heterogeneous and multiscale deformation processes that current single-scale kinematic models cannot explain. To relate isolated L-tectonites in a high-strain zone with its boundary conditions, I apply a multiscale approach. Isolated L-tectonites are regarded …

The Synthesis And Reactivity Of Novel Donor-Acceptor Cyclopropanes And Progress Towards Pyrrolidine Alkaloids, Michael R. Emmett

Electronic Thesis and Dissertation Repository

The first chapter of this thesis focuses on the synthesis and reactivity of cyclopropane hemimalonates. The cyclopropane hemimalonates can easily be synthesized from 1,1-cyclopropanediesters. The reactivity of cyclopropane hemimalonates with indole under ultra-high pressure conditions leads to ring opened adducts that are complementary to previous research in the Kerr group. The tandem ring opening decarboxylation reaction of cyclopropane hemimalonates led to the synthesis of γ-aminobutyric acid analogues. When an external nucleophile was not present, the cyclopropane hemimalonates could rearrange to form butyrolactones in good to excellent yields. The stereochemical integrity of the cyclopropane hemimalonate is retained through this process, which …

Tilting Sheaves On Brauer-Severi Schemes And Arithmetic Toric Varieties, Youlong Yan

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The derived category of coherent sheaves on a smooth projective variety is an important object of study in algebraic geometry. One important device relevant for this study is the notion of tilting sheaf.

This thesis is concerned with the existence of tilting sheaves on some smooth projective varieties. The main technique we use in this thesis is Galois descent theory. We first construct tilting bundles on general Brauer-Severi varieties. Our main result shows the existence of tilting bundles on some Brauer-Severi schemes. As an application, we prove that there are tilting bundles on an arithmetic toric variety whose toric variety …

Observational Signatures From Self-Gravitating Protostellar Disks, Alexander L. Desouza

Electronic Thesis and Dissertation Repository

Protostellar disks are the ubiquitous corollary outcome of the angular momentum conserving, gravitational collapse of molecular cloud cores into stars. Disks are an essential component of the star formation process, mediating the accretion of material onto the protostar, and for redistributing excess angular momentum during the collapse. We present a model to explain the observed correlation between mass accretion rates and stellar mass that has been inferred from observations of intermediate to upper mass T Tauri stars. We explain this correlation within the framework of gravitationally driven torques parameterized in terms of Toomre’s Q criterion. Our models reproduce both the …

Understanding Recurrent Disease: A Dynamical Systems Approach, Wenjing Zhang

Electronic Thesis and Dissertation Repository

Recurrent disease, characterized by repeated alternations between acute relapse and long re- mission, can be a feature of both common diseases, like ear infections, and serious chronic diseases, such as HIV infection or multiple sclerosis. Due to their poorly understood etiology and the resultant challenge for medical treatment and patient management, recurrent diseases attract much attention in clinical research and biomathematics. Previous studies of recurrence by biomathematicians mainly focus on in-host models and generate recurrent patterns by in- corporating forcing functions or stochastic elements. In this study, we investigate deterministic in-host models through the qualitative analysis of dynamical systems, to …

Electrogenerated Chemiluminescence Of Gold Nanoclusters, Mahdi Hesari

Electronic Thesis and Dissertation Repository

A series of monodispersed AuNCs including Au144(SR)60, Au38(SR)24 and Au25(SR)18z (z =1-, 0 and 1+, SR=2-phenylethanethiol) were prepared. All these nanoclusters showed molecule-like optical and electrochemical properties. These two features are essential for an electrogenerated chemiluminescence or electrochemiluminescence (ECL) study. The Au144(SR)60 showed a small HOMO-LUMO gap determined by electrochemistry. No ECL light was seen in the annihilation process, while NIR ECL was observed with tri-n- propylamine (TPrA) (Chapter 2). ECL was highly efficient in the Au38(SR)24/TPrA co- reactant system. This nanocluster also showed ECL emission with benzoyl peroxide (BPO), while no ECL was detected in the annihilation route (Chapter …

Application Of Mn(Iii) Oxidative Cyclizations To Natural Product Synthesis, Bryan Landschoot

Electronic Thesis and Dissertation Repository

This work begins with a brief review of manganese(III) acetate free radical oxidative cyclization chemistry and its application toward functionalizing nitrogen containing heterocycles. Exploration of a cyclopropane ring opening reaction using indoline, and subsequent manganese(III) cyclization chemistry will be presented as a possible route towards a family of natural products called the flinderoles. Work on the construction of the core of several indole alkaloids from the genus Tabernaemontana, including tronocarpine, chippiine, and dippinine B, will be explored with utilization of manganese(III) cyclizations. Hopes of accessing an advanced common intermediate for each of these natural products will be discussed due …

Identification Of Informativeness In Text Using Natural Language Stylometry, Rushdi Shams

Electronic Thesis and Dissertation Repository

In this age of information overload, one experiences a rapidly growing over-abundance of written text. To assist with handling this bounty, this plethora of texts is now widely used to develop and optimize statistical natural language processing (NLP) systems. Surprisingly, the use of more fragments of text to train these statistical NLP systems may not necessarily lead to improved performance. We hypothesize that those fragments that help the most with training are those that contain the desired information. Therefore, determining informativeness in text has become a central issue in our view of NLP. Recent developments in this field have spawned …

New Ligands For Lanthanides And Transition Metals Toward Magnetic Resonance Imaging Contrast Agents, Melissa M. Lewis

Electronic Thesis and Dissertation Repository

MRI is a non-invasive technique used in medical imaging. Although contrast agents have been used to enhance the image generated by MRI, it still suffers the major shortcoming of low sensitivity. This has led to a thrust to develop contrast agents that improve sensitivity by relaxivity and CEST. This thesis describes attempts made to aid in the development of sensitive MRI contrast agents.

Chapter 2 investigated pH dependent reversible binding on CEST effect and relaxivity in DO3AM complexes possessing a lone p-nitrophenol arm. Unfortunately, only the Tb³⁺complex had a small CEST signal. T₁ relaxivity of the …

Oxidative Cyclizations Of Tertiary Pentenols And The Synthesis Of Β-Carboline Alkaloids, Geoffrey A. Phillips

Electronic Thesis and Dissertation Repository

This thesis describes the work carried out on two projects. The first chapter of the thesis discusses the application of the second generation Co(nmp)2 catalyst towards the oxidative cyclization of tertiary pentenols through a modified Mukaiyama aerobic oxidative cyclization procedure.

The second chapter describes the progress made towards the synthesis of β-carboline alkaloids. The total synthesis of the alkaloid natural product cyclocapitelline is detailed along with the formal synthesis of the natural product chrysotricine.

Automated Image Interpretation For Science Autonomy In Robotic Planetary Exploration, Raymond Francis

Electronic Thesis and Dissertation Repository

Advances in the capabilities of robotic planetary exploration missions have increased the wealth of scientific data they produce, presenting challenges for mission science and operations imposed by the limits of interplanetary radio communications. These data budget pressures can be relieved by increased robotic autonomy, both for onboard operations tasks and for decision- making in response to science data.

This thesis presents new techniques in automated image interpretation for natural scenes of relevance to planetary science and exploration, and elaborates autonomy scenarios under which they could be used to extend the reach and performance of exploration missions on planetary surfaces.

Two …

Development Of A Gallium-Containing One-Bead One-Compound Peptide Library For The Discovery Of New Molecular Imaging Probes, Fernanda C. Bononi

Electronic Thesis and Dissertation Repository

An eight amino acid one-bead one-compound (OBOC) peptide library, containing a gallium-DOTA complex, was developed in an attempt to overcome common issues associated with the later addition of radionuclides to peptide chains of imaging probes. The further addition of a radionuclide often changes the binding properties of a peptide, as it adds bulk, and possibly charges. MALDI (matrix-assisted laser desorption ionization) tandem mass spectrometry was determined to be the method of choice in order to deconvolute gallium-containing peptide sequences. The library obtained was screened against the breast cancer cell lines MDA-MB-231 and MCF-7. Positive beads were isolated and sequences were …

Valuation And Risk Measurement Of Guaranteed Annuity Options Under Stochastic Environment, Huan Gao

Electronic Thesis and Dissertation Repository

This thesis develops stochastic modelling frameworks for the accurate pricing and risk management of complex insurance products with option-embedded features. We propose stochastic models for the evolution of the two main risk factors, the interest rate and mortality rate, which could also have a correlation structure. For the valuation problem, a general framework is put forward where correlated interest and mortality rates are modelled as affine-diffusion processes. A new concept of endowment-risk-adjusted measure is introduced to facilitate the calculation of the GAO value. As a natural offshoot of addressing GAO valuation, we derive the convex-order upper and lower bounds of …

Polynomial Identities On Algebras With Actions, Chris Plyley

Electronic Thesis and Dissertation Repository

When an algebra is endowed with the additional structure of an action or a grading, one can often make striking conclusions about the algebra based on the properties of the structure-induced subspaces. For example, if A is an associative G-graded algebra such that the homogeneous component A₁ satisfies an identity of degree d, then Bergen and Cohen showed that A is itself a PI-algebra. Bahturin, Giambruno and Riley later used combinatorial methods to show that the degree of the identity satisfied by A is bounded above by a function of d and |G|. Utilizing a …

Estimation Of Hidden Markov Models And Their Applications In Finance, Anton Tenyakov

Electronic Thesis and Dissertation Repository

Movements of financial variables exhibit extreme fluctuations during periods of economic crisis and times of market uncertainty. They are also affected by institutional policies and intervention of regulatory authorities. These structural changes driving prices and other economic indicators can be captured reasonably by models featuring regime-switching capabilities. Hidden Markov models (HMM) modulating the model parameters to incorporate such regime-switching dynamics have been put forward in recent years, but many of them could still be further improved. In this research, we aim to address some of the inadequacies of previous regime-switching models in terms of their capacity to provide better forecasts …

The X-Ray View Of Galaxies In Compact Groups And The Coma Cluster Infall Region, Tyler D. Desjardins

Electronic Thesis and Dissertation Repository

In this thesis, we have explored what information may be gleaned from X-ray observations of galaxies in dense environments. We use X-ray observations from XMM- Newton and the Chandra X-ray Observatory, and multi-wavelength ancillary data, to investigate the X-ray emission of galaxies. First, we study the distribution and properties of the intragroup diffuse X-ray emission in compact groups (CGs) of galaxies. From a sample of 19 CGs, we find the morphology of hot gas in low-mass groups is varied, and most systems have hot gas (if any) associated with only individual members. The galaxy-linked hot gas is coupled with high …

Transit Demand Estimation And Crowding Prediction Based On Real-Time Transit Data, Michael Aro

Electronic Thesis and Dissertation Repository

With an increasing number of intelligent analytic techniques and increasing networking capabilities, municipal transit authorities can leverage real-time data to estimate transit volume and predict crowding conditions. We introduce a proactive Transit Demand Estimation and Prediction System (TraDEPS) – an approach that has the potential to prevent crowding and improve transit service, by measuring the transit activity (the number of passengers on the individual modes of public transportation and the demand on a route), and estimating crowding levels at a given time. This system utilizes a combination of real-time data streams from multiple sources, a predictive model and data analytics …

Ghost Number Of Group Algebras, Gaohong Wang

Electronic Thesis and Dissertation Repository

The generating hypothesis for the stable module category of a finite group is the statement that if a map in the thick subcategory generated by the trivial representation induces the zero map in Tate cohomology, then it is stably trivial. It is known that the generating hypothesis fails for most groups. Generalizing work done for p-groups, we define the ghost number of a group algebra, which is a natural number that measures the degree to which the generating hypothesis fails. We describe a close relationship between ghost numbers and Auslander-Reiten triangles, with many results stated for a general projective class …

Options Pricing And Hedging In A Regime-Switching Volatility Model, Melissa A. Mielkie

Electronic Thesis and Dissertation Repository

Both deterministic and stochastic volatility models have been used to price and hedge options. Observation of real market data suggests that volatility, while stochastic, is well modelled as alternating between two states. Under this two-state regime-switching framework, we derive coupled pricing partial differential equations (PDEs) with the inclusion of a state-dependent market price of volatility risk (MPVR) term.

Since there is no closed-form solution for this pricing problem, we apply and compare two approaches to solving the coupled PDEs, assuming constant Poisson intensities. First we solve the problem using numerical solution techniques, through the application of the Crank-Nicolson numerical scheme. …

A Spatial Analysis Of Forest Fire Survival And A Marked Cluster Process For Simulating Fire Load, Amy A. Morin

Electronic Thesis and Dissertation Repository

The duration of a forest fire depends on many factors, such as weather, fuel type and fuel moisture, as well as fire management strategies. Understanding how these impact the duration of a fire can lead to more effective suppression efforts as this information can be incorporated into decision support systems used by fire management agencies to help allocate suppression resources. This thesis presents a thorough survival analysis of lightning and people-caused fires in the Intensive fire management zone of Ontario, Canada from 1989 through 2004. The analysis is then extended to investigate spatial patterns across this region using proportional hazards …

The Influence Of Microstructure On The Corrosion Of Magnesium Alloys, Robert M. Asmussen

Electronic Thesis and Dissertation Repository

This thesis reports a series of investigations into the influence of microstructure on the corrosion of Mg alloys. Mg alloys are prime candidates for the light-weighting of automobiles however any extensive applications are limited by their high corrosion rates. The corrosion resistance is further hindered by the susceptibility of Mg alloys to microgalvanic coupling occurring between the Mg matrix and the secondary microstructures in the alloys. This process and the individual contributions to it must be understood to improve Mg alloy design for automotive applications, develop methods for extending the lifetime of Mg alloys and developing models to successfully predict …

Plasmonic Optical Sensors: Performance Analysis And Engineering Towards Biosensing, Peipei Jia

Electronic Thesis and Dissertation Repository

Surface plasmon resonance (SPR) sensing for quantitative analysis of chemical reactions and biological interactions has become one of the most promising applications of plasmonics. This thesis focuses on performance analysis for plasmonic sensors and implementation of plamonic optical sensors with novel nanofabrication techniques.

A universal performance analysis model is established for general two-dimensional plasmonic sensors. This model is based on the fundamental facts of surface plasmon theory. The sensitivity only depends on excitation light wavelength as well as dielectric properties of metal and dielectrics. The expression involves no structure-specified parameters, which validates this formula in broad cases of periodic, quasiperiodic …

Observational And Theoretical Investigation Of Cylindrical Line Source Blast Theory Using Meteors, Elizabeth A. Silber

Electronic Thesis and Dissertation Repository

During their passage through the atmosphere meteoroids produce a hypersonic shock which may be recorded at the ground in the form of infrasound. The first objective of this project was to use global infrasound measurements to estimate the influx of large (meter/decameter) objects to Earth and investigate which parameters of their ablation and disruption can be determined using infrasound records. A second objective was to evaluate and extend existing cylindrical line source blast theory for meteoroids by combining new observations with earlier analytical models, and validate these against centimetre-sized optical meteor observations.

The annual terrestrial influx of large meteoroids (kinetic …

On The Applications Of Lifting Techniques, Esmaeil Mehrabi

Electronic Thesis and Dissertation Repository

Lifting techniques are some of the main tools in solving a variety of different computational problems related to the field of computer algebra. In this thesis, we will consider two fundamental problems in the fields of computational algebraic geometry and number theory, trying to find more efficient algorithms to solve such problems.

The first problem, solving systems of polynomial equations, is one of the most fundamental problems in the field of computational algebraic geometry. In this thesis, We discuss how to solve bivariate polynomial systems over either k(T ) or Q using a combination of lifting and modular composition techniques. …

A Non-Contrast Magnetic Resonance Imaging Technique To Assess Blood-Brain Barrier Permeability, Harini Pandithasekera

Electronic Thesis and Dissertation Repository

The Blood-brain barrier (BBB) regulates the entry of compounds between the blood and the brain, thus plays an important role in brain homeostasis. Studies indicate in disease states such as Alzheimer’s the BBB integrity is compromised. The motive of this project is to investigate the sensitivity of the diffusion-weighted arterial spin labeling (DW-ASL) technique to detect water exchange. Testing the sensitivity requires a reliable method of opening the barrier at specific locations of the brain. Here, a unique technology named focused ultrasound (FUS) has been used to mimic a compromised BBB environment.

A series of experiments were conducted in a …

Cosine Similarity For Article Section Classification: Using Structured Abstracts As A Proxy For An Annotated Corpus, Arthur T. Bugorski

Electronic Thesis and Dissertation Repository

During the last decade, the amount of research published in biomedical journals has grown significantly and at an accelerating rate. To fully explore all of this literature, new tools and techniques are needed for both information retrieval and processing. One such tool is the identification and extraction of key claims. In an e ort to work toward claim-extraction, we aim to identify the key areas in the body of the article referred to by text in the abstract. In this project, our work is preliminary to that goal in that we attempt to match specific clauses in the abstract with …

Shock Metamorphic Effects In Lunar And Terrestrial Plagioclase Feldspar Investigated By Optical Petrography And Micro-X-Ray Diffraction, Annemarie E. Pickersgill

Electronic Thesis and Dissertation Repository

Shock metamorphism, caused by hypervelocity impact, is a poorly understood process in feldspar. This thesis addresses: a) developing a quantitative scale of shock deformation in plagioclase feldspar; b) expanding the utility of plagioclase feldspar for determining shock level; and c) micro-X-ray diffraction as a technique with which to study shock in feldspar.

Andesine and labradorite from the Mistastin Lake impact structure, Labrador, Canada, and anorthite from Earth’s moon, returned during the Apollo program, show shock effects such as diaplectic glass. Planar deformation features are absent in plagioclase, but abundant in terrestrial quartz. A pseudomorphous zeolite phase (levyne-Ca) was identified as …

Statistical Applications In Wildfire Management And Prediction, Lengyi Han

Electronic Thesis and Dissertation Repository

This thesis develops statistical methods and models and applies them
to problems related to forest fires. The unifying goal of the work is to provide a data analytic basis for quantifying the uncertainty surrounding fire ignition and fire growth which builds on existing theory where possible.

The main body of the thesis is comprised of three research papers. The Fire Weather Index (FWI) plays an important role in fire management and is central to the first two papers. In the first instance, the block bootstrap confidence interval method is used to deal nonparametrically with the dependence in the FWI data. …