Physical Sciences and Mathematics Commons^™

Vascular Tree Structure: Fast Curvature Regularization And Validation, Egor Chesakov

Electronic Thesis and Dissertation Repository

This work addresses the challenging problem of accurate vessel structure analysis in high resolution 3D biomedical images. Typical segmentation methods fail on recent micro-CT data sets resolving near-capillary vessels due to limitations of standard first-order regularization models. While regularization is needed to address noise and partial volume issues in the data, we argue that extraction of thin tubular structures requires higher-order curvature-based regularization. There are no standard segmentation methods regularizing surface curvature in 3D that could be applied to large 3D volumes. However, we observe that standard measures for vessels structure are more concerned with topology, bifurcation angles, and other …

The Effects Of Warming Temperatures, Fire, And Landscape Change On Lake Production In Mountain Lakes, Alberta, Canada, Amber Elizabeth Gall

Electronic Thesis and Dissertation Repository

Many factors could be causing the widespread eutrophication being observed globally, including natural and human factors. In the mountainous regions of Alberta, Canada, warming temperatures, increased fire occurrence, and greater landscape disturbance could increase lake production. To determine the effects of these factors, proxies of lake production preserved in lake sediment records that span the last 1000 years were measured. These records are from two lakes that have not been affected by direct nutrient inputs from human activities; one in Jasper National Park and one from the Hinton area (Alberta). The results highlight that there is little effect of fire …

Recent Discoveries In The Ni-Cu-Pge Bearing Trill And Parkin Offset Dykes, Sudbury Impact Structure, Canada, Adam B. Coulter

Electronic Thesis and Dissertation Repository

The Sudbury structure hosts world class Ni-Cu-PGE deposits that have been mined, explored and studied for over 130 years. The structure is widely recognized as the erosional remnant of a 1.85 Ga 200- to 250-km tectonically altered multi-ring impact basin located in central Ontario, Canada. The focus of this investigation is on the Trill and Parkin Offset dykes. This study provides updated regional scale geologic maps, detailed geologic maps of newly exposed sections, geochemistry, sulphide analysis and an analysis of the inclusion population and orientation within the dykes. We conclude, the dyke phases display remarkable geochemical homogeneity, the Ni-Cu-PGE mineralization …

The Mistastin Lake Impact Structure As A Terrestrial Analogue Site For Lunar Science And Exploration, Marianne M. Mader

Electronic Thesis and Dissertation Repository

The impact cratering record on the Moon is important for many reasons, from understanding early solar system chronology to probing the lunar interior. In order to maximize scientific return from future lunar missions, it is useful to: 1) study terrestrial impact craters to better understand impact processes and products, and 2) develop appropriate human and robotic exploration strategies aligned with geological goals.

This research shows that the intermediate-size Mistastin Lake impact structure, in northern Labrador, Canada, is an unparalleled lunar analogue site, which includes both an anorthositic target and an almost complete suite of impact lithologies, including proximal ejecta deposits. …

Vibrational Imaging At The Nanoscale: Surpassing The Diffraction Limit Using Tip-Enhanced Raman Spectroscopy, Farshid Pashaee

Electronic Thesis and Dissertation Repository

A deep understanding of the chemical composition of surfaces, interfaces or nanoscale structure with a high spatial resolution is an important goal in nanoscience and nanotechnology. Structural information can be collected using a variety of high spatial resolution techniques such as atomic force microscopy (AFM), scanning tunneling microscopy (STM), scanning electron microscopy (SEM), or transmission electron microscopy (TEM). Nevertheless, these methods do not offer molecular information such as vibrational spectroscopy techniques that allow one to collect molecular or lattice vibrations yielding to a precise picture of the molecular interactions in bulk materials as well as in surfaces and interfaces. Unfortunately …

Silver Nanoparticle Transport Through Soil: Illuminating The Governing Pore-Scale Processes, Ian L. Molnar

Electronic Thesis and Dissertation Repository

Engineered nanoparticles are widely used and will eventually be released to the subsurface environment and contaminate groundwater resources. However, the transport of engineered nanoparticles through soil is currently not well understood and cannot be modelled in any fundamental manner, placing groundwater resources at risk from nanoparticle contamination. This inability to accurately simulate transport is due to a lack of experimental information on nanoparticle interactions in the pore spaces of real soils.

This thesis illuminates the pore-scale processes governing silver nanoparticle transport through soil. In addition, it examines the influence of surface chemistry and grain/pore distributions on those processes. For the …

Bm3d Image Denoising Using Learning-Based Adaptive Hard Thresholding, Farhan Bashar

Electronic Thesis and Dissertation Repository

Image denoising is an important pre-processing step in most imaging applications. Block Matching and 3D Filtering (BM3D) is considered to be the current state-of-art algorithm for additive image denoising. But this algorithm uses a fixed hard thresholding scheme to attenuate noise from a 3D block. Experiments show that this fixed hard thresholding deteriorates the performance of BM3D because it does not consider the context of corresponding blocks. In this thesis, we propose a learning based adaptive hard thresholding method to solve this issue. Also, BM3D algorithm requires as an input the value of the noise level in the input image. …

Adaptive Non-Local Means Using Weight Thresholding, Asif Khan

Electronic Thesis and Dissertation Repository

Non-local means (NLM) is a popular image denoising scheme for reducing additive Gaussian noise. It uses a patch-based approach to find similar regions within a search neighborhood and estimate the denoised pixel based on the weighted average of all the pixels in the neighborhood. All the pixels are considered for averaging, irrespective of the value of their weights. This thesis proposes an improved variant of the original NLM scheme, called Weight Thresholded Non-Local Means (WTNLM), by thresholding the weights of the pixels within the search neighborhood, where the thresholded weights are used in the averaging step. The key parameters of …

Solvothermal Synthesis And Characterization Of Cuins2, Cuinse2 And Agins2 Nanoparticles From Single Source Precursors, Xuzhao Zhao

Electronic Thesis and Dissertation Repository

Nanoscale semiconductors have emerged as alternative candidates for the absorber layer in solar cells. Group 11-13-16 semiconductors have received a lot attention because of their direct band gap energies, high absorption coefficients and environmental friendly nature. To date, CuInS₂, CuInSe₂ and AgInS₂ semiconductors are three of the main ternary nanomaterials investigated. Besides the application in solar cells, these nanoscale semiconductors can also be applied in areas such as biosensors and hydro catalysis.

However, it is often challenging to prepare small-sized nanoparticles with uniform size and shape, especially for large scale production. In this thesis, the synthesis …

Morphological, Structural And Spectral Mapping Of The Central Uplifts Of The Alga And Verlaine Craters, Mars, Bianca D'Aoust

Electronic Thesis and Dissertation Repository

Impact cratering is a ubiquitous geological process that has shaped planetary bodies of the Solar System and beyond. While the impact cratering record on Earth has been poorly preserved, the Martian surface is characterized by a very old and cratered terrain. Central uplifts within complex impact craters are of particular interest as they expose deep-seated material, some of which may correspond to samples of the early Martian crust. Central uplift formation is, however, still a poorly understood geological process. This research investigated the origin of the exposed bedrock in the central uplifts of two Martian complex craters as well as …

Optical Flow At Occlusion Boundaries And In Occlusion Regions, Hua Meng

Electronic Thesis and Dissertation Repository

Optical flow is an important research area in the Computer Vision field, with the estimation of optical flow at occlusion still an open problem. Traditional approaches to this problem have either used additional terms in a regularization calculation (the flow still tends to “bleed” across occlusion boundaries) or a local least squares calculation that attempted to minimize the influence of two adjacent differently moving regions on the optical flow at points close to both regions (the flow still tends to be “corrupted” by the two regions). Ideally, optical flow for two adjacent differently moving regions should be distinct right up …

Surface Reconstruction From Noisy And Sparse Data, Mark A. Brophy

Electronic Thesis and Dissertation Repository

We introduce a set of algorithms for registering, filtering and measuring the similarity of unorganized 3d point clouds, usually obtained from multiple views.

We contribute a method for computing the similarity between point clouds that represent closed surfaces, specifically segmented tumors from CT scans. We obtain watertight surfaces and utilize volumetric overlap to determine similarity in a volumetric way. This similarity measure is used to quantify treatment variability based on target volume segmentation both prior to and following radiotherapy planning stages.

We also contribute an algorithm for the drift-free registration of thin, non- rigid scans, where drift is the build-up …

Recent Advances In Accumulating Priority Queues, Na Li

Electronic Thesis and Dissertation Repository

This thesis extends the theory underlying the Accumulating Priority Queue (APQ) in three directions. In the first, we present a multi-class multi-server accumulating priority queue with Poisson arrivals and heterogeneous services. The waiting time distributions for different classes have been derived. A conservation law for systems with heterogeneous servers has been studied. We also investigate an optimization problem to find the optimal level of heterogeneity in the multi-server system. Numerical investigations through simulation are carried out to validate the model.

We next focus on a queueing system with Poisson arrivals, generally distributed service times and nonlinear priority accumulation functions. We …

A New Technique For Interpreting Depolarization Measurements Using The Crl Atmospheric Lidar In The Canadian High Arctic, Emily M. Mccullough

Electronic Thesis and Dissertation Repository

Linear depolarization measurement capabilities were added to the CANDAC Rayleigh-Mie-Raman lidar (CRL) at Eureka, Nunavut, in the Canadian High Arctic. This upgrade enables inferences of the phases (liquid versus ice) of cold and mixed-phase clouds, including during polar winter. A rotating-polarizer module was installed in the lidar, and depolarization measurements were calibrated according to existing methods. An alternate calculation technique, using the lidar's existing visible Rayleigh elastic channel in combination with the new rotating polarizer channel, was developed. A detailed mathematical description of both methods and their calibrations is presented. The new method is superior to the traditional method for …

Galois 2-Extensions, Masoud Ataei Jaliseh

Electronic Thesis and Dissertation Repository

The inverse Galois problem is a major question in mathematics. For a given base field and a given finite group $G$, one would like to list all Galois extensions $L/F$ such that the Galois group of $L/F$ is $G$.

In this work we shall solve this problem for all fields $F$, and for group $G$ of unipotent $4 \times 4$ matrices over $\mathbb{F}_2$. We also list all $16$ $U_4 (\mathbb{F}_2)$-extensions of $\mathbb{Q}_2$. The importance of these results is that they answer the inverse Galois problem in some specific cases.

This is joint work with J\'an Min\'a\v{c} and Nguyen Duy T\^an.

Studies Of Contingent Capital Bonds, Jingya Li

Electronic Thesis and Dissertation Repository

A contingent capital bond (CCB) is a subordinated security that converts to common shares when a predetermined trigger is breached. The 2008 financial crisis and the Basel III motivate the issuance of CCBs, aiming to mitigate the too-big-to-fail problem in financial distress and to resolve financial institutions by bailing in with the firm’s own capital rather than a bailing out using the taxpayers’ money.

Within the structural modelling framework, we consider the pricing of CCBs with an affine geometric Brownian motion by assuming that coupon payments have impact on the asset value dynamics. We extend the capital structure into four …

High Pressure Studies Of Nanostructured Tio2 And Li4ti5o12 Using Raman Spectroscopy And Synchrotron X-Ray Radiation, Fengping Xiao

Electronic Thesis and Dissertation Repository

Nanomaterials have been extensively studied due to their distinctive properties such as surface effect, small-size effect and quantum size effect. In recent year, investigations of the structural and phase transformations of nanomaterials under high pressure are receiving increasing attentions. In addition to composition and synthetic routes, pressure provides a clean way to adjust interatomic distance and hence affect the crystal structure and thus properties of the nanostructured materials.Two nanomaterials (i.e. TiO₂ and Li₄Ti₅O₁₂) with different morphologies are studied in this thesis.

In part I, the high-pressure behaviours of four hydrothermal synthesized 1D rutile …

A Novel Method For Assessing Co-Monotonicity: An Interplay Between Mathematics And Statistics With Applications, Danang T. Qoyyimi

Electronic Thesis and Dissertation Repository

Numerous problems in econometrics, insurance, reliability engineering, and statistics rely on the assumption that certain functions are monotonic, which may or may not be true in real life scenarios. To satisfy this requirement, from the theoretical point of view, researchers frequently model the underlying phenomena using parametric and semi-parametric families of functions, thus effectively specifying the required shapes of the functions. To tackle these problems in a non-parametric way, when the shape cannot be specified explicitly but only estimated approximately, we suggest indices for measuring the lack of monotonicity in functions. We investigate properties of these indices and offer convenient …

The Influence Of Alloying Elements On The Crevice Corrosion Behaviour Of Ni-Cr-Mo Alloys, Nafiseh Ebrahimi

Electronic Thesis and Dissertation Repository

To enhance its corrosion resistance in aggressive media, Ni is alloyed with various amounts of Cr and Mo along with small amounts of other alloying elements such as W, Cu, and Fe. While the resulting alloys (known as Ni superalloys) show excellent passive behaviour, the function of individual alloying elements in resisting localized corrosion processes, in particular crevice corrosion is not fully understood. This study focuses on the electrochemistry and corrosion of a series of Ni-Cr-Mo (W) alloys with various Cr and Mo contents. Several electrochemical and surface characterization techniques were used to investigate the role of major alloying elements …

Reflectance And Emission Spectroscopy: Curve Fitting Methods With Application To Impact Glasses And The Varying Grain Size Of Planetary Analogue Minerals, Michael A. Craig

Electronic Thesis and Dissertation Repository

Spectroscopy, i.e., the measurement of electromagnetic radiation as a function of wavelength, is arguably the technique most responsible for the majority of what is collectively known about the composition of stars, the distances to galaxies, the age of the universe and so on. Spectroscopy is also the tool most used to discern the mineralogy of planetary bodies remotely. Measuring the speed at which a star is receding and its composition, or the composition of an interstellar cloud of gas are well understood uses of spectroscopy. When it comes to spectroscopies use to discern mineralogy, the scientific literature on the subject …

Nitrogen Abundances In Early-Type Be Stars, Ahmed Ahmed

Electronic Thesis and Dissertation Repository

A sample of 26 Be stars from the Magnetism in Massive Stars (MiMeS) spectroscopic survey are analyzed for their photospheric nitrogen abundances in an effort to detect rotational mixing in the Be stars. Be stars are massive stars, between 3 and 20 times the mass of the Sun, that are surrounded by a thin, equatorial disk of gas that produces emission lines in their optical and near-infrared spectra. Be stars are the most rapidly-rotating stellar population on the main sequence, where stars produce energy by core hydrogen burning. New, non-LTE line transfer calculations are performed for the Nii ion, the …

The Corrosion Behaviour Of Cu In Irradiated And Non-Irradiated Humid Air, Balsam Ibrahim

Electronic Thesis and Dissertation Repository

The present management scenario for the permanent disposal of high level nuclear waste in Canada is to seal it in metallic containers and bury it in a deep stable geologic repository. For thick-walled containers radiation fields on the outside of the container would have a negligible influence on container corrosion. However, to overcome fabrication issues and to reduce costs, steel containers with a thin outer copper coating are being designed making a reassessment of the influence of gamma radiation on container corrosion a potential licensing requirement.

The behaviour of Cu in an aerated vapour phase environment in equilibrium with condensed …

Hyperpolarized 129xe Magnetic Resonance Imaging Of Radiation-Induced Lung Injury, Ozkan Doganay

Electronic Thesis and Dissertation Repository

Lung cancer is the largest contributor to cancer-related mortality worldwide. Only 20% of stage III non-small cell lung cancer patients survive after 5-years post radiation therapy (RT). Although RT is an important treatment modality for lung cancer, it is limited by Radiation-Induced Lung Injury (RILI). RILI develops in two phases: (i) the early phase (days-weeks) referred to radiation pneumonitis (RP), and (ii) the late phase (months). There is a strong interest in early detection of RP using imaging to improve outcomes of RT for lung cancer. This thesis describes a promising approach based on ¹²⁹Xe gas as a contrast …

Characterizing Seismicity In Alberta For Induced-Seismicity Applications, Luqi Cui

Electronic Thesis and Dissertation Repository

This report documents the compilation of a high-quality catalog of earthquakes in Alberta and the surrounding region: the Composite Alberta Seismicity Catalog (CASC). It currently includes events through July 2015. The catalog and its documentation are available for download at www.inducedseismicity.ca. For the determination of the magnitude of completeness (M_c) of the catalog, we map M_c (x_i, y_i, t) across a grid of the region, where x_i and y_i represent the longitude and latitude of center nodes in the grid and t indicates time period. The empirical …

High Resolution Tropospheric Studies With An Mst Type Radar, Marcial Garbanzo-Salas

Electronic Thesis and Dissertation Repository

Applications and results of a variety of studies carried out with the Costa Rican VHF profiler radar are included. This radar is unique because of the wide frequency bandwidth available (5 MHz). During the developing stages of the wind profiler radar new techniques of processing and radar engineering were used.

A thorough analysis of a data-dependent method (Capon's) commonly used in radar was carried out. This method is analyzed based on a reference established by Fourier theory. Disadvantages of using data-dependent methods with small filters were found. A small filter size will cause Capon's method to underestimate the number of …

Formal Models Of The Extension Activity Of Dna Polymerase Enzymes, Srujan Kumar Enaganti

Electronic Thesis and Dissertation Repository

The study of formal language operations inspired by enzymatic actions on DNA is part of ongoing efforts to provide a formal framework and rigorous treatment of DNA-based information and DNA-based computation. Other studies along these lines include theoretical explorations of splicing systems, insertion-deletion systems, substitution, hairpin extension, hairpin reduction, superposition, overlapping concatenation, conditional concatenation, contextual intra- and intermolecular recombinations, as well as template-guided recombination.

First, a formal language operation is proposed and investigated, inspired by the naturally occurring phenomenon of DNA primer extension by a DNA-template-directed DNA polymerase enzyme. Given two DNA strings u and v, where the shorter …

Factors Controlling The Composition And Lithofacies Characteristics Of The Paleoproterozoic Bar River Formation, Huronian Supergroup, Rohan Dj Aranha

Electronic Thesis and Dissertation Repository

The Bar River Formation of the Paleoproterozoic Huronian Supergroup is one of the earliest sedimentary formations deposited following Earth’s Great Oxidation Event. Ten quartz-rich lithofacies were identified near Flack Lake, Ontario. Lithofacies associations resemble multiple, stacked tidal inlet fill sequences, common to mesotidal shorelines. Sedimentary structures, such as herringbone cross-stratification, reactivation surfaces, and wave ripples, support tidal and wave action. Paleocurrent patterns are bimodal to polymodal with a mean paleoflow to the southeast. Potential sources northwest of the study area include Archean Superior Province rocks and the Paleoproterozoic Lorrain Formation. Major and trace element, and oxygen isotope geochemistry support either …

Evolution Of Mobile Promoters In Prokaryotic Genomes., Mahnaz Rabbani

Electronic Thesis and Dissertation Repository

Mobile genetic elements are important factors in evolution, and greatly influence the structure of genomes, facilitating the development of new adaptive characteristics. The dynamics of these mobile elements can be described using various mathematical and statistical models. In this thesis, we focus on a specific category of mobile genetic elements, i.e. mobile promoters, which are mobile regions of DNA that initiate the transcription of genes. We present a class of mathematical models for the evolution of mobile promoters in prokaryotic genomes, based on data obtained from available sequenced genomes. Our novel location-based model incorporates two biologically meaningful regions of the …

Mass Spectrometric Analyses Of Surface Proteins From Candida Albicans After Treatment With Histatin 5, Shirley Fan

Electronic Thesis and Dissertation Repository

Current drug therapies have lost their effectiveness in controlling the fungal species known as C. albicans; therefore, the need for newer drugs becomes crucial. Histatin 5 (Hst 5), a naturally occurring peptide found in the oral cavity, has demonstrated strong effects on controlling candidiasis. Here, we have proposed that the adhesion of cells through surface proteins is an important process. To allow the analysis of surface proteins, the concept of on-whole cell tryptic digestions were developed. This on-target approach allows for isolation of the peptides of interest, while greatly reducing digestion times.

To study the effects of Histatin 5 …

Carbon And Nitrogen Isotopic Investigations Of The Late Pleistocene Paleoecology Of Eastern Beringia, Yukon Territory, Using Soils, Plants And Rodent Bones, Farnoush Tahmasebi

Electronic Thesis and Dissertation Repository

During the late Pleistocene (130-12 ka), Beringia, a largely ice-free land located in the Mammoth Steppe Ecosystem, was home to a large grazing community of megafauna. Many of these animals, including the woolly mammoth, became extinct at the terminal Pleistocene. Assessment of the paleoenvironment, nutrient cycling and foraging ecology in Beringia should help to understand the role of climate change in their extirpation. Such information might also help to explain the curiously higher δ¹⁵N of woolly mammoths relative to other coeval herbivores.

This study assessed eastern Beringian paleoecology using stable nitrogen (N) and carbon (C) isotopic analyses of …