Physical Sciences and Mathematics Commons^™

All-Optical Switching In Ferromagnetic Superlattices., Faren Hoveyda Marashi

Electronic Theses and Dissertations

The unexpected observation of ultrafast demagnetization (UDM) and subsequent time-resolved studies of laser-induced magnetization switching opened a new door to both fundamental physics and technological applications of magnetic materials. All-optical switching (AOS) can be initiated faster than the precession limit, hinting to its potential in increasing the writing speed and data storage density. However, notwithstanding considerable research interest, the mechanism of AOS in ferromagnetic materials remained unclear.

Ferromagnetic superlattices were deposited on glass substrates with e-beam evaporation and sputtering. Magnetization curves were measured in magneto-optical and vibrating sample magnetometer experiments. A femtosecond Ti:S laser was utilized in a writing setup …

Functional Data Analysis Methods For Predicting Disease Status., Sarah Kendrick

Electronic Theses and Dissertations

Introduction: Differential scanning calorimetry (DSC) is used to determine thermally-induced conformational changes of biomolecules within a blood plasma sample. Recent research has indicated that DSC curves (or thermograms) may have different characteristics based on disease status and, thus, may be useful as a monitoring and diagnostic tool for some diseases. Since thermograms are curves measured over a range of temperature values, they are often considered as functional data. In this dissertation we propose and apply functional data analysis (FDA) techniques to analyze DSC data from the Lupus Family Registry and Repository (LFRR). The aim is to develop FDA methods to …

Graph Analytics Methods In Feature Engineering, Theophilus Siameh

Electronic Theses and Dissertations

High-dimensional data sets can be difficult to visualize and analyze, while data in low-dimensional space tend to be more accessible. In order to aid visualization of the underlying structure of a dataset, the dimension of the dataset is reduced. The simplest approach to accomplish this task of dimensionality reduction is by a random projection of the data. Even though this approach allows some degree of visualization of the underlying structure, it is possible to lose more interesting underlying structure within the data. In order to address this concern, various supervised and unsupervised linear dimensionality reduction algorithms have been designed, such …

A Framework For Clustering And Adaptive Topic Tracking On Evolving Text And Social Media Data Streams., Gopi Chand Nutakki

Electronic Theses and Dissertations

Recent advances and widespread usage of online web services and social media platforms, coupled with ubiquitous low cost devices, mobile technologies, and increasing capacity of lower cost storage, has led to a proliferation of Big data, ranging from, news, e-commerce clickstreams, and online business transactions to continuous event logs and social media expressions. These large amounts of online data, often referred to as data streams, because they get generated at extremely high throughputs or velocity, can make conventional and classical data analytics methodologies obsolete. For these reasons, the issues of management and analysis of data streams have been researched extensively …

Spatially Explicit Model Of Areas Between Suitable Black Bear Habitat In East Texas And Black Bear Populations In Louisiana, Arkansas, And Oklahoma, Caitlin M. Glymph, Christopher Comer, Daniel Scognamillo, Daniel Unger, Yanli Zhang

Electronic Theses and Dissertations

Although black bears (Ursus americanus, Ursus americanus luteolus) were once found throughout the south-central United States, unregulated harvest and habitat loss resulted in severe range retractions and by the beginning of the twentieth century populations in Oklahoma, Louisiana, Texas and Arkansas were nearing extirpation. In response to these losses, translocation programs were initiated in Arkansas (1958-1968 & 2000-2006) and Louisiana (1964-1967 & 2001-2009). These programs successfully restored bears to portions of Louisiana and Arkansas, and, as populations in Arkansas began dispersing, to Oklahoma. In contrast, east Texas remains unoccupied despite the existence of suitable habitat in the region.

To facilitate …

The Sequence Stratigraphic Context Of Mixed Basin Margin Evaporites In The Harrisburg Member Of The Permian Kaibab Formation, Northern Arizona And Southern Utah, Cole Hendrickson

Electronic Theses and Dissertations

The Kaibab Formation is a mixed carbonate system including evaporites and siliciclastics deposited on a westward dipping epeiric carbonate ramp during the middle Permian in northern Arizona, southern Utah, and eastern Nevada. It consists of the Fossil Mountain Member deposited in open-marine conditions and the overlying Harrisburg Member deposited in restricted conditions. The Harrisburg Member includes facies and depositional environments ranging from open-marine shallow-subtidal wackestone - packstone, restricted subtidal dolomitic mudstone, dolomitic sandstone, peritidal oolitic grainstone as well as gypsum and red siltstones deposited in a sabkha environment.

Fourteen stratigraphic sections were measured across northern Arizona and southern Utah to …

Integrated Environment And Proximity Sensing For Uav Applications, Shawn S. Brackett

Electronic Theses and Dissertations

As Unmanned Aerial Vehicle (UAV), or “drone” applications expand, new methods for sensing, navigating and avoiding obstacles need to be developed. The project applies an Extended Kalman Filter (EKF) to a simulated quadcopter vehicle though Matlab in order to estimate not only the vehicle state but the world state around the vehicle. The EKF integrates multiple sensor readings from range sensors, IMU sensors, and radiation sensors and combines this information to optimize state estimates. The result is an estimated world map to be used in vehicle navigation and obstacle avoidance.

The simulation handles the physics behind the vehicle flight. As …

Renewable Hydrogels From Norbornene-Functionalized Carboxymethyl Cellulose And A Short Dithiol Crosslinked Via A Thiol-Ene Reaction, Thomas Mcoscar

Electronic Theses and Dissertations

Cellulose-based hydrogels - three dimensional "solid" structures composed primarily of liquid water and held together by an interconnected polymer network - were created by first functionalizing carboxymethyl cellulose (CMC), a cellulose derivative, with carbic anhydride in a basic aqueous reaction with the intent of developing novel hydrogels from renewable materials. The product of this reaction, carbic CMC (cCMC), had a new norbornene group as a subsection of the carbic group. Norbornene is a reactive alkene structure that allows for further chemistry with cCMC, such as crosslinking. cCMC was crosslinked with 2,2'-(ethylenedioxy)diethathiol to create hydrogels using a water-soluble, UV-sensitive radical initiator …

Using Hydroacoustics To Investigate Biological Responses In Fish Abundance To Restoration Efforts In The Penobscot River, Maine, Constantin C. Scherelis

Electronic Theses and Dissertations

Spatiotemporal advantages linked to hydroacoustic sampling techniques have caused a surge in the use of these techniques for fisheries monitoring studies applied over long periods of time in marine systems. Dynamic physical conditions such as tidal height, boat traffic, floating debris, and suspended particle concentrations result in unwanted noise signatures that vary in intensity and location within a hydroacoustic beam over time and can be mixed with the acoustic returns from intended targets (e.g., fish). Typical processing filters applied over long term datasets to minimize noise and maximize signals do not address spatiotemporal fluctuations of noise in dynamic systems. We …

Oyster Aquaculture Site Selection Using Landsat 8-Derived Sea Surface Temperature, Turbidity, And Chlorophyll A., Jordan Snyder

Electronic Theses and Dissertations

Remote sensing data is useful for selection of aquaculture sites because it can provide water-quality products mapped with no cost to users. However, the spatial resolution of most ocean color satellites is too coarse to provide usable data within many estuaries. The more recently launched Landsat 8 satellite has both the spatial resolution and the necessary signal to noise ratio to provide temperature, as well as ocean color derived products along complex coastlines. The state of Maine (USA) has an abundance of estuarine indentations (~3,500 miles of tidal shoreline within 220 miles of coast), and an expanding aquaculture industry, which …

Creating Renewable Tunable Polymers From Hydroxymethylfurfural, Meredith C. Allen

Electronic Theses and Dissertations

The research here deals with the conversion of 5-hydroxymethylfurfural (HMF) into a tunable polymer. HMF is a known derivative that can be acquired from biomass via hydrolysis of cellulose followed by isomerization and finally selective dehydration. The process considered here is being developed to create tunable polymers from HMF and involves several different steps, three of which are covered here. The first step, an etherification, is the reaction of HMF with an alcohol. This step is significant because in this step the R-group from the alcohol is added to HMF and the branching portion formed is carried over to the …

In Situ Dating Of Multiple Events In Granulite-Facies Rocks Of The Larsemann Hills, Prydz Bay, East Antarctica Using Electron Microprobe Analysis Of Monazite, Steven K. Spreitzer

Electronic Theses and Dissertations

The metamorphic rocks exposed along the southeast coast of Prydz Bay were affected by several metamorphic and plutonic events associated with collision in the Neoproterozoic and Cambrian. Critical units exposed in the Larsemann Hills and nearby ice-free areas include (1) basement Søstrene Orthogneiss, (2) cover sequence Brattstrand Paragneiss and (3) anatectic pegmatites intrusive into the Brattstrand Paragneiss. Zircon U-Pb data from previous studies yielded a maximum depositional age of 1023 ± 19 Ma for the Brattstrand Paragneiss, but only approximate ca. 900 Ma to ca. 1000 Ma and ca. 530 Ma ages for two metamorphic events. In order to constrain …

Examination And Comparison Of The Performance Of Common Non-Parametric And Robust Regression Models, Gregory F. Malek

Electronic Theses and Dissertations

ABSTRACT

Examination and Comparison of the Performance of Common Non-Parametric and Robust Regression Models

By

Gregory Frank Malek

Stephen F. Austin State University, Masters in Statistics Program,

Nacogdoches, Texas, U.S.A.

g_m_2002@live.com

This work investigated common alternatives to the least-squares regression method in the presence of non-normally distributed errors. An initial literature review identified a variety of alternative methods, including Theil Regression, Wilcoxon Regression, Iteratively Re-Weighted Least Squares, Bounded-Influence Regression, and Bootstrapping methods. These methods were evaluated using a simple simulated example data set, as well as various real data sets, including math proficiency data, Belgian telephone call data, and faculty …

Window Inserts And The People Adopting Them: Building Sustainable Communities In Maine, Daniel Sean Mistro

Electronic Theses and Dissertations

Residents of Maine face a large monetary expense to heat their homes in the winter. In Maine it takes 540 gallons of heating oil each year to heat a typical home [1]. Interior window inserts may be a practical solution to improve comfort, save money, and consume less environmentally harmful fossil fuels during cold winter months. The window inserts discussed in this paper are custom measured to fit into a window and consist of a wooden frame that is wrapped in two layers of polyolefin film and weather stripped for a snug fit. Commercial inserts cost $20-$36/square foot, or approximately …

Regularized Solutions For Terminal Problems Of Parabolic Equations., Sujeewa Indika Hapuarachchi

Electronic Theses and Dissertations

The heat equation with a terminal condition problem is not well-posed in the sense of Hadamard so regularization is needed. In general, partial differential equations (PDE) with terminal conditions are those in which the solution depends uniquely but not continuously on the given condition. In this dissertation, we explore how to find an approximation problem for a nonlinear heat equation which is well-posed. By using a small parameter, we construct an approximation problem and use a modified quasi-boundary value method to regularize a time dependent thermal conductivity heat equation and a quasi-boundary value method to regularize a space dependent thermal …

Sea Lamprey (Petromyzon Marinus) As A Functional Link Between Marine And Freshwater Ecosystems, Daniel M. Weaver

Electronic Theses and Dissertations

Anadromous sea lamprey Petromyzon marinus are native to Atlantic coastal systems and serve as a functional link between marine and freshwater ecosystems. Sea lamprey spend 1–2 years in the ocean parasitizing marine vertebrates before migrating into freshwaters during the spring to spawn. There they construct nests, spawn, then die shortly afterwards. Larvae hatch, bury into fine sediments and reside in streams for generally 6–8 years, but up to 14. Larvae then undergo metamorphosis, a non-feeding period characterized by a series of physical and physiological changes. The juveniles (macropthalmia) then migrate to the ocean to begin the parasitic juvenile phase.

Historically, …

Vertex Weighted Spectral Clustering, Mohammad Masum

Electronic Theses and Dissertations

Spectral clustering is often used to partition a data set into a specified number of clusters. Both the unweighted and the vertex-weighted approaches use eigenvectors of the Laplacian matrix of a graph. Our focus is on using vertex-weighted methods to refine clustering of observations. An eigenvector corresponding with the second smallest eigenvalue of the Laplacian matrix of a graph is called a Fiedler vector. Coefficients of a Fiedler vector are used to partition vertices of a given graph into two clusters. A vertex of a graph is classified as unassociated if the Fiedler coefficient of the vertex is close to …

A Novel Method For Synthesis Of Hydroxytyrosol, Emmanuel Onobun

Electronic Theses and Dissertations

Hydroxytyrosol, 3,4-dihydroxyphenolethanol, a naturally occurring polyphenol most common in olive tree (Olea europaea), is one of the most effective member of the polyphenols family, because of its remarkable antioxidant activity, its ability to inhibit oxidation of low density lipids (LDL), and its protection against DNA oxidative damage. Hydroxytyrosol, which is widely used in cosmetics and food supplements industries, can be purchased as an olive oil extract that contains low concentration of hydroxytyrosol besides other polyphenols. The price and low natural abundance of hydroxytyrosol make alternative synthetic sources very attractive. In this research, a novel method for the synthesis of pure …

Vulnerability Assessment Of Groundwater To No3 Contamination Using Gis, Drastic Model And Geostatistical Analysis, Adela Beauty Adu Agyemang

Electronic Theses and Dissertations

The study employed Geographical Information System (GIS) technology to investigate the vulnerability of groundwater to NO₃ content in Buncombe County, North Carolina in two different approaches. In the first study, the spatial distribution of NO₃ contamination was analyzed in a GIS environment using Kriging Interpolation. Cokriging interpolation was used to establish how NO₃ relates to land cover types and depth to water table of wells in the county. The second study used DRASTIC model to assess the vulnerability of groundwater in Buncombe County to NO₃ contamination. To get an accurate vulnerability index, the DRASTIC parameters were …

Groundwater Flow Tracing In Carter Saltpeter Cave And Toll Branch, Carter County, Tn, Aaron G. Doyka

Electronic Theses and Dissertations

Groundwater tracing studies have shown a well-developed conduit system in the karst aquifer beneath the Buffalo Creek Watershed of Carter County, TN. Groundwater can quickly travel beneath topographic divides, transporting contaminants. Using GIS and field reconnaissance, two sites were selected for a two phase dye trace study. In May-June 2016 groundwater resurgences were located using activated carbon samplers, and in October-December 2016 flow velocities were measured using ISCO automatic water samplers. In study 1, a stream sinking in the back of Carter Saltpeter Cave was traced to its resurgence at Cave Springs Cave. In study 2, the dye mass centroid …

Accurate And Justifiable : New Algorithms For Explainable Recommendations., Behnoush Abdollahi

Electronic Theses and Dissertations

Websites and online services thrive with large amounts of online information, products, and choices, that are available but exceedingly difficult to find and discover. This has prompted two major paradigms to help sift through information: information retrieval and recommender systems. The broad family of information retrieval techniques has given rise to the modern search engines which return relevant results, following a user's explicit query. The broad family of recommender systems, on the other hand, works in a more subtle manner, and do not require an explicit query to provide relevant results. Collaborative Filtering (CF) recommender systems are based on algorithms …

Ecological Informatics: An Agent Based Model On Coexistence Dynamics, Shiva Thapa

Electronic Theses and Dissertations

The coexistence of species is probably one of the most interesting and complex phenomenon in nature. We constructed an agent based model to study the coexistence dynamics of prey - predator populations by varying productivity levels of producers in fragmented and connected habitats along with different levels of quality of predators. Our results indicated that productivity levels of producers in fragmented and connected habitats along with levels of predator quality are significantly responsible for overall predator - prey population size and survivorship. In the absence of predation, competition between identical prey populations is more probable in connected habitats than in …

A Data Science Pipeline For Educational Data : A Case Study Using Learning Catalytics In The Active Learning Classroom., Asuman Cagla Acun Sener

Electronic Theses and Dissertations

This thesis presents an applied data science methodology on a set of University of Louisville, Speed School of Engineering student data. We used data mining and classic statistical techniques to help educational researchers quickly see the data trends and peculiarities. Our data includes scores and information about two Engineering Fundamental Class. The format of these classes is called an inverted classroom model or flipped class. The purpose of this study is to analyze the data in order to uncover potentially hidden information, tell interesting stories about the data, examine student learning behavior and learning performance in an active learning environment, …

Likelihood-Based Methods For Analysis Of Copy Number Variation Using Next Generation Sequencing Data., Udika Iroshini Bandara

Electronic Theses and Dissertations

A Copy Number Variation (CNV) detection problem is considered using Circular Binary Segmentation (CBS) procedures, including newly developed procedures based on likelihood ratio tests with the parametric bootstrap for models based on discrete distributions for count data (Poisson and negative binomial) and a widely-used DNAcopy package. Results from the literature concerning maximum likelihood estimation for the negative binomial distribution are reviewed. The Newton-Raphson method is used to find the root of the derivative of the profile log likelihood function when applicable, and it is proven that this method converges to the true Maximum Likeihood Estimate (MLE), if the starting point …

Some Problems Arising From Mathematical Model Of Ductal Carcinoma In Situ., Heng Li

Electronic Theses and Dissertations

Ductal carcinoma in situ (DCIS) is the earliest form of breast cancer. Three mathematical models in the one dimensional case arising from DCIS are proposed. The first two models are in the form of parabolic equation with initial and known moving boundaries. Direct and inverse problems are considered in model 1, existence and uniqueness are proved by using tool from heat potential theory and Volterra integral equations. Also, we discuss the direct problem and nonlocal problem of model 2, existence and uniqueness are proved. And approximation solution of these problems are implemented by Ritz-Galerkin method, which is the first attempt …

Extending Difference Of Votes Rules On Three Voting Models., Sarah Schulz King

Electronic Theses and Dissertations

In a voting situation where there are only two competing alternatives, simple majority rule outputs the alternatives with the most votes or declares a tie if both alternatives receive the same number of votes. For any non-negative integer k, the difference of votes rule M_k outputs the alternative that beats the competing alternative by more than k votes. Llamazares (2006) gives a characterization of the difference of votes rules in terms of five axioms. In this thesis, we extend Llamazares' result by completely describing the class of voting rules that satisfy only two out of his five axioms. …

Controlled Electrochemical Synthesis Of Single One-Dimensional Metal Nanochains Across Microgap Electrodes., Amareshwari Konutham

Electronic Theses and Dissertations

This study mainly focuses on the fabrication of single one dimensional (1D) NP chains across the 5-micron gap of Au two electrode devices (TED). This has been achieved by electrochemical deposition of Ag onto the two electrodes, soaking the TED in 0.1 M Cetyltrimethyl ammonium bromide for 2-3 hours, and then close monitoring of the current as a function of time while a voltage across the two Ag coated Au electrodes in air. One dimensional Ag nanoparticle chain formation occurred by oxidation of Ag to Ag⁺ at the positive electrode followed by movement of Ag⁺ ions to the …

Dynamic Adversarial Mining - Effectively Applying Machine Learning In Adversarial Non-Stationary Environments., Tegjyot Singh Sethi

Electronic Theses and Dissertations

While understanding of machine learning and data mining is still in its budding stages, the engineering applications of the same has found immense acceptance and success. Cybersecurity applications such as intrusion detection systems, spam filtering, and CAPTCHA authentication, have all begun adopting machine learning as a viable technique to deal with large scale adversarial activity. However, the naive usage of machine learning in an adversarial setting is prone to reverse engineering and evasion attacks, as most of these techniques were designed primarily for a static setting. The security domain is a dynamic landscape, with an ongoing never ending arms race …

Residuated Maps, The Way-Below Relation, And Contractions On Probabilistic Metric Spaces., M. Ryan Luke

Electronic Theses and Dissertations

In this dissertation, we will examine residuated mappings on a function lattice and how they behave with respect to the way-below relation. In particular, which residuated $\phi$ has the property that $F$ is way-below $\phi(F)$ for $F$ in appropriate sets. We show the way-below relation describes the separation of two functions and how this corresponds to contraction mappings on probabilistic metric spaces. A new definition for contractions is considered using the way-below relation.

Water-Soluble Pd And Pd-Alloy Nanoparticles As Catalysts In Biphasic Solvent., Shekhar Bhama

Electronic Theses and Dissertations

This dissertation shows the chemical synthesis of Pd and Pd-alloy nanoparticles (NPs) and their hydrogen and thermal stabilities for applications in the homogeneous and pseudo-homogeneous catalysis of organic reactions. Mainly, this dissertation describes 1) the chemical synthesis of Pd, PdPt, PdAu and Cu-Pd core-shell NPs coated with various organic ligands (thiols, amines and citrate), with different metal compositions in different synthetic environment, 2) the stability of solutions containing various NPs in the presence of hydrogen or varying temperatures, 3) the evaluation of the catalytic activity of Pd, PdPt, PdAu and CuPd NPs for hydrogenation/isomerization of allylic alcohols, and 4) the …