Physical Sciences and Mathematics Commons^™

Geochemical Controls On Mercury Methylation In Backwaters Of A Gulf Coastal Plain River System, Implications For Water Column Processes, Liam N. Schenk

Graduate Theses and Dissertations

The abundance and distribution of mercury and methyl mercury were investigated at three sites in the lower Ouachita River in the summer of 2010 in an effort to provide the first characterization of the extent of mercury contamination in this river system, and to investigate the potential for mercury methylation in the water column of backwaters off of the main channel. Results showed that filtered methyl mercury was positively correlated to dissolved organic carbon (r2=0.76) for water samples taken from the bottom 1 ft of the water column at three sites, suggesting the importance of dissolved organic carbon in mercury …

Symmetry-Based Techniques For Qualitative Understanding Of Rovibrational Effects In Spherical-Top Molecular Spectra And Dynamics, Justin Chadwick Mitchell

Graduate Theses and Dissertations

Using light to probe the structure of matter is as natural as opening our eyes. Modern physics and chemistry have turned this art into a rich science, measuring the delicate interactions possible at the molecular level.

Perhaps the most commonly used tool in computational spectroscopy is that of matrix diagonalization. While this is invaluable for calculating everything from molecular structure and energy levels to dipole moments and dynamics, the process of numerical diagonalization is an opaque one. This work applies symmetry and semi-classical techniques to elucidate numerical spectral analysis for high-symmetry molecules.

Semi-classical techniques, such as the Potential Energy Surfaces, …

Protein-Lipid Interactions: Influence Of Anchoring Groups And Buried Arginine On The Properties Of Membrane-Spanning Peptides, Vitaly V. Vostrikov

Graduate Theses and Dissertations

Designed transmembrane peptides were employed for investigations of protein-lipid interactions by means of oriented solid-state deuterium NMR spectroscopy using isotope-enriched alanine residues. Using the model GWALP23 sequence (GGALW(LA)6LWLAGA) as a host peptide having single interfacial tryptophan anchor residues, the effects of different guest mutations were explored. Replacements of glycine residues 2 and 22 to positively charged lysine or arginine on both termini had little influence on the peptide average orientation. Conversely, glycine to tryptophan substitutions had profound effects, manifested in the increased dynamics and altered tilt direction of the peptide. While the charged residues at the peptide termini did not …

A Restarted Homotopy Method For The Nonsymmetric Eigenvalue Problem, Brandon Hutchison

Graduate Theses and Dissertations

The eigenvalues and eigenvectors of a Hessenberg matrix, H, are computed with a combination of homotopy increments and the Arnoldi method. Given a set, Ω, of approximate eigenvalues of H, there exists a unique vector f = f(H,Ω) in Rn where λ(H-e_{1ft)=Ω. A diagonalization of the homotopy H(t)=H−(1−t)e1ft at $t=0$ provides a prediction of the eigenvalues of H(t) at later times. These predictions define a new Ω that defines a new homotopy. The correction for each eigenvalue has an O(t2) error estimate, enabling variable step size and efficient convergence tests. Computations are done primarily in real arithmetic, and …}

Spatial Variations In Willingness To Pay For Water At The Local And Regional Scales Using Geographically Weighted Regression, Robyn Lane Dennis

Graduate Theses and Dissertations

Two decades of rapid urban growth and increasing per capita water consumption has left water providers in Northwest Arkansas concerned about their ability to meet future demand for water. Beaver Water District (BWD) is the largest of four regional water providers that draw from Beaver Lake, the only source of potable water in the region. Growth projections and per capita consumption patterns indicate that BWD could exhaust its raw water allocation as early as 2031. Municipal water customers served by BWD were surveyed about their stated priorities for water use, their water conservation behaviors, and their attitudes and perceptions about …

Holomorphic Hardy Space Representations For Convex Domains In Cn, Jennifer West Paulk

Graduate Theses and Dissertations

This thesis deals with Hardy Spaces of holomorphic functions for a domain in several complex variables, that is, when the complex dimension is greater than or equal to two. The results we obtain are analogous to well known theorems in one complex variable. The domains we are concerned with are strongly convex with real boundary of class C^2. We obtain integral representations utilizing the Leray kernel for Hardy space (p=1) functions on such domains D. Next we define an operator to prove the non-tangential limits of a function in Hardy space (p between 1 and infinity, inclusive) of domain D …

Recommendations For The Chamlidere Petrified Forest Management Plan, Fatma Ertem

Graduate Theses and Dissertations

Anything inherited from our ancestors or from nature can be considered as our heritage. Heritage can be classified as cultural and natural heritage. Turkey has been the cradle of many civilizations, religions, and ethnic groups because of the unprecedented natural heritage and critical geopolitical location of Anatolia. Given all the treasure of cultural and natural heritage in Turkey, heritage management practices have not been emphasized as they deserve. A petrified forest was found in Chamlidere, Ankara (Turkey) in 2004. Chamlidere petrified forest preserves information related to the biodiversity of forests in the Galatian Volcanic Province during the Early-Middle Miocene. When …

Factors That Influence The Adoption Of Agricultural Conservation Programs In Northwest Arkansas, Edison Anthony Froelich

Graduate Theses and Dissertations

A survey was developed and administered to agricultural producers in Northwest Arkansas in order to better understand producer awareness of, application for and participation in six federal and state conservation programs available in Arkansas: the Environmental Quality Incentives Program, the Conservation Reserve Enhancement Program, the Arkansas Revolving Loan Program, the Arkansas Nonpoint Pollution Management Program , the Arkansas Soil Nutrient and Poultry Litter Application and Management Program, and the Surplus Poultry Litter Removal Incentives Cost Share Program. Survey results found that less than half of the sample was aware of any one of the programs. A logit model was developed …

Redox-Magnetohydrodynamic (Mhd) Microfluidics: Fundamentals, Optimization, And Applications To Analytical Chemistry, Melissa Christine Weston

Graduate Theses and Dissertations

Microfluidic systems are of great interest in analytical chemistry for the development of lab-on-a-chip devices. This dissertation describes fundamental investigations of magnetohydrodynamics with added redox species (redox-MHD) as a new microfluidic approach for use in analytical applications. Redox-MHD is attractive because it offers a unique combination of desirable features that are otherwise only available separately with individual micropumps. Redox-MHD is compatible with aqueous and nonaqueous solutions, does not require moving parts, easily reverses flow direction, and requires only low voltages. An ion flux is generated from the oxidation or reduction of an electroactive species at specific locations by activated electrodes …

Two Essays On The Accounting Treatment For Information Technology Expenditures, Kimberly Swanson Church

Graduate Theses and Dissertations

The current accounting measurement and reporting system is ill-equipped to provide intangible investment information that is decision useful for stakeholders in the information economy. Potentially relevant intangible items are not reported on the balance sheet, since current standards mandate the immediate expensing of these intangible items. Presumably FASB's uncertainty with the fundamental issues of extent and timing of future benefits to the firm has led to concerns with relevance, reliability, and objectivity of capitalizing some intangibles, which results in potential long term value generating expenditures being immediately expensed on the income statement. Prior research has demonstrated extent and timing of …

Linkage Of Asteroids And Meteorites By The Study Of Terrestrial Analogs, Daniel Robert Ostrowski

Graduate Theses and Dissertations

Asteroids are one group of the bodies that can provide insights into the origin and early history of the solar system. Asteroids are considered to be fairly pristine, with alterations only occurring to their surface from the space environment. Studying them provides opportunities to learn about the primordial solar system, its materials, and processes and how it evolved into the current condition. Many asteroids have been discovered, but few have their surface compositions determined. The C and X complexes provide a difficulty in determination because their near infrared spectrum is featureless.

The C asteroids have been long associated with the …

Evaluation Of Best Management Practices To Reduce Nutrients Runoff In Watersheds In Arkansas, Hector German Rodriguez Diaz

Graduate Theses and Dissertations

There are many non point sources (NPS) of pollution issues across the state of Arkansas. Each region of the state has different concerns. Many watersheds have been included in the Arkansas's 2008 303(d) list for NPS impairments with sediment and nutrients being the primary causes of concern. This research hypothesized that there are no cost or net returns risks when adopting best management practices (BMPs) to control nutrients runoff and that selection, timing, placement and cost have no impact on the implementation of BMPs. Using two priority watersheds, the L'Anguille River and the Lincoln Lake, as examples, the environmental benefits …

New Infrared Spectral Data For 27 Asteroids: An Investigation Of Meteorite-Asteroid Relationships By Using The Modified Gaussian Model, Katherine Marie Gietzen

Graduate Theses and Dissertations

Asteroids provide unique insights into the origin and early history of the solar system. Since asteroids are considered to be fairly pristine, studying them provides opportunities to learn more about the primordial solar system, its materials, processes and history. Since the discovery in 1801 of the first asteroid, Ceres, during the era when everyone was searching for the "missing planet", astronomers have been trying to understand what they are, where they came from, why they exist and what they can tell us about how our solar system formed and evolved.

Within the asteroid population are a number of sub-populations, the …

Factors Affecting Redox Magnetohydrodynamics For Flow In Small Volumes, Matthew D. Gerner

Graduate Theses and Dissertations

Lab-on-a-chip technologies offer the possibility of developing analytical devices that are low-cost, portable, disposable, fast, and operable by non-technical personnel. Such devices require automated methods to manipulate ultra-small volumes (picoliters) of samples and solution, including pumping, stirring, and positioning. Current methods for ultra-small volume microfluidics have limitations that restrict their use including high voltage requirements, disadvantageous flow profiles or rates, and relatively complicated fabrication due to mechanical parts. Redox magnetohydrodyanmics (RMHD) that utilizes permanent magnets for portability shows promise as a micropump with ease of switching flow direction, no moving parts, compatibility with both aqueous and non-aqueous solutions, low voltages …

Imaging Second-Harmonic Radiation And Scattering Patterns In Zno Micro/Nanostructures, Katrina Marie Geren

Graduate Theses and Dissertations

The optical characteristics of ZnO nanostructures have recently garnered interest due to the inclusion of these structures in many nanoscale optical and optoelectronic devices. This thesis will address several characteristics involving second harmonic generation and scattering in ZnO nano- and microstructures. A method will be presented for determining the nonlinear coefficients of the second order susceptibility in a single ZnO rod. This method uses transmission geometry where previous methods have employed back-reflected irradiation. The nonlinear coefficients found using this new technique were consistent with previous data from similar structures. Models will be presented for predicting the second harmonic scattering patterns …

Modeling Of Compositionally Graded Barium Strontium Titanate From First Principles, Laura Elizabeth Walizer

Graduate Theses and Dissertations

"Barium Strontium Titanate (BaxSr1-xTiO3 or BST) is a Perovskite alloy of interest for both technological and intellectual reasons. Its ferroelectric and piezoelectric properties make it useful in a variety of electric components such as transducers and actuators, and BST in particular is a material of interest for the development of a ferroelectric RAM for computers. The inclusion of SrTiO3, an incipient ferroelectric, and the fact that the properties of a BST system depend strongly on its relative composition of BaTiO3 and SrTiO3 (ST), make also this a material of high interest. Compositionally graded systems are of further interest , partly …

Predicting Success In High School Computer Programming, John C. Gevedon

Graduate Theses and Dissertations

There are great differences in performance among students taking high school programming courses, and instructors debate over what elements contribute to these differences. Some students develop logical thinking abilities and problem solving techniques, while others fail to develop skills beyond memorization of specific terms and procedures. It is not known whether these differences are causally related to the specific educational environment or student backgrounds. Without more information, the factors that actually contribute to the success of high school students in computer programming courses cannot be accurately determined. It was the purpose of this study then to isolate certain student characteristics …