Physical Sciences and Mathematics Commons^™

Water Quality Trends For Section 319 Priority Watersheds In Northwest Arkansas, 1997-2010, Bryan William Bailey

Graduate Theses and Dissertations

Northwest Arkansas contains two Section 319 Priority Watersheds that the Arkansas Natural Resources Commission (ANRC) has identified as being impacted by point and nonpoint sources of pollution (i.e., phosphorus, nitrogen, and sediment), and the Arkansas Water Resources Center (AWRC) has monitored the water quality at several sites within these watersheds. Water-quality data has been collected over the last decade within the Illinois River Watershed (HUC #11110103) and the Upper White River Basin (Beaver Reservoir HUC# 11010001), each watershed containing three sampling sites. The Illinois River Watershed sites are located on the Illinois River, Osage Creek, and Ballard Creek, and the …

Dynamics And Catalytic Resolution Of Selected Chiral Organolithiums, Timothy Kum Beng

Graduate Theses and Dissertations

One of the most important developments of the last decade has been the emergence of new methods to dynamically resolve racemic organolithiums using stoichiometric amounts of the chiral ligand. When this concept is implemented successfully, it obviates the need for covalently attached chiral auxiliary based methods, asymmetric deprotonation, and asymmetric synthesis of a precursor stannane as ways to access enantioenriched organolithium compounds for use in asymmetric synthesis. Since certain electrophiles consume the chiral ligand, it is desirable to render this process catalytic in the chiral ligand.

As part of a larger study on the amenability of chiral organolithiums to a …

Nitrogen Retention And Denitrification In Reservoirs, Erin Grantz

Graduate Theses and Dissertations

Studies coupling direct measurements of micro-scale nitrogen (N) cycle processes with ecosystem-scale flux estimates are needed to determine N retention hotspots within river networks, where up to 50% of terrestrial loading to aquatic systems is retained. This study examined the role of denitrification, a microbially-mediated reactive N removal pathway, in ecosystem-scale N retention in 3 small (< 1 km2), shallow flood-control reservoirs. Annual reservoir N retention was estimated through mass balance modeling of system inputs and outputs. Annual denitrification rates were estimated by combining multiple measurements of seasonal, habitat-specific dinitrogen gas (N2) fluxes. Annual reservoir N retention ranged from 14 - 19 g m-2 in the reservoirs, while reactive N removal through denitrification was 13 - 25 g m-2. Denitrification efficiency, or the portion of the retained N load that was denitrified, was high relative to other lentic systems and was > 100% at 2 sites. Previous lentic denitrification studies may have underestimated denitrification efficiency by not considering water column denitrification, which was 50% of total denitrification at one study reservoir. However, not all potential inputs, most importantly biological N2 fixation, were included in this …

Subcritical Water Hydrolysis Of Whey Proteins, Ashley Dawn Espinoza

Graduate Theses and Dissertations

Hydrolyzing food by-products is a unique approach to potentially increase by-product value and reduce waste. An abundant by-product of cheese production, whey, contains all essential amino acids and some distinctive peptides with functional and nutraceutical properties. Typically, proteins from whey are tailored for specific uses by chemical or enzymatic hydrolysis; however, subcritical water hydrolysis is a novel alternative used successfully to hydrolyze various substrates. Nevertheless, minimal research exists on: (1) the hydrolysis of whey protein; (2) the incorporation of additives; (3) the hydrolysis of whole whey; and (4) the production of volatiles when using subcritical water hydrolysis.

Therefore, whey protein …

Geospatial Tools And Techniques For Watershed Management Using Swat 2009, Naresh Pai

Graduate Theses and Dissertations

In this study, geospatial tools and techniques were developed to support specific aspects of watershed pollution management, such as quantifying land-use change (LUC) impacts, prioritizing subwatersheds, and communicating field-scale impacts, using the soil and water assessment tool 2009 (SWAT 2009) model.

For the land-use change objective, a geospatial tool titled SWAT2009_LUC was developed that enables SWAT modelers to prepare specific input files for simulating concurrent land-use changes during the SWAT 2009 model simulations. Testing of the tool for the Illinois River Drainage Area in Arkansas (IRDAA) watershed showed that the tool accurately represented temporal land-uses within the model. Model simulations …

Field-Based Constraints On The Origin Of The Benton Uplift, Ouachita Mountains, Rachel Victoria Keng

Graduate Theses and Dissertations

The Ouachita Mountains are an east-west trending fold-and-thrust belt exposed in west central Arkansas and southeastern Oklahoma. The Mississippian-Pennsylvanian Ouachita orogeny occurred when the Sabine arc terrane collided during south-facing subduction, during closure of the Cambrian passive margin of the North American plate. Deep-water Paleozoic strata were incorporated into an accretionary wedge as the Sabine terrane approached the North American plate. Folds and thrust faults in the Ouachita Mountains generally verge north due to tectonic transport of an accretionary wedge from south to north. Structures in the Benton and Broken Bow Uplifts (located in the core of the wedge) locally …

Defining, Executing And Visualizing Representative Workflows In A Retail Domain, May Zeineldin

Graduate Theses and Dissertations

Our lives are filled with routine activities that we do more or less on auto-pilot such as driving to work and cooking. This thesis explores a workflow representation as a way to represent such activities of daily living. The domain of a retail store environment is used. Workflows are initially expressed in a structured English representation, then translated into a Petri net notation and implemented in mix of Petri nets, Lua, and C so that the resulting workflows can be displayed as the actions of collections of avatarbots (avatars controlled by programs) in a 3D virtual world, Second Life. One …

Visualizing The Spatial Localization Of Active Matrix Metalloproteinases (Mmps) Using Maldi Imaging Ms, Sasirekha Muruganantham

Graduate Theses and Dissertations

Biomaterial implantation induces the foreign body response (FBR). Development of longer-term implants relies on the thorough understanding of the FBR. The progression of the FBR is regulated by a number of biomolecules including cytokines, chemokines, and matrix metalloproteinases (MMPs). The nature of the FBR requires the spatial and temporal regulation of these mediators. MMPs are an extremely large and diverse group of enzymes that play key roles in regulating the FBR. Precise spatiotemporal regulation of MMPs defines their proteolytic activities. The aim of this project is to develop a new bioanalytical method to visualize the localization of active MMPs at …

The Design, Synthesis And Application Of A Novel Class Of N-Heterocyclic Carbene Catalysts, Abigail Lynn Hubbard

Graduate Theses and Dissertations

A copper carbenoid representative of a novel class of N-heterocyclic carbene (NHC) catalysts has been synthesized. This compound was characterized by X-ray crystallography and was found to confirm the rationale of our synthetic design: The C2-symmetric structure places four stereocenters in close proximity (<5Å) to the reactive site of the carbene via a trans-annular gearing effect. The copper carbenoid was found to catalyze the hydrosilylation of prochiral ketones with superb selectivity in high yield.

High Performance Geospatial Analysis On Emerging Parallel Architectures, Seth Warn

Graduate Theses and Dissertations

Geographic information systems (GIS) are performing increasingly sophisticated analyses on growing data sets. These analyses demand high performance. At the same time, modern computing platforms increasingly derive their performance from several forms of parallelism. This dissertation explores the available parallelism in several GIS-applied algorithms: viewshed calculation, image feature transform, and feature analysis. It presents implementations of these algorithms that exploit parallel processing to reduce execution time, and analyzes the effectiveness of the implementations in their use of parallel processing.

Critical Torque For Kink Formation In Double-Stranded Dna, Hao Qu, Yong Wang, Chiao-Yu Tseng, Giovanni Zocchi

Physics Faculty Publications and Presentations

We measure the bending energy of double-stranded DNA in the nonlinear (sharply bent) regime. The measurements are obtained from the melting curves of stressed DNA ring molecules. The nonlinear elastic behavior is captured by a single parameter: the critical torque τc at which the molecule develops a kink. In this regime, the elastic energy is linear in the kink angle. This phenomenology is the same as for the previously reported case of nicked DNA. For the sequences examined, we find τc=31 pN×nm. This critical torque corresponds to a characteristic energy scale (π/2)τc=12 kT room relevant for molecular biology processes associated …

Assessing Ageing At Beaver Reservoir, Northwest Arkansas: Limnological, Geochemical & Paleolimnological Approach, Byron Anthony Winston

Graduate Theses and Dissertations

Access to potable water has been arguably one of the most important requisites for the advancement of human civilization on earth. As a result, man in his infinite wisdom devised the dam and formed reservoirs, (man- made lakes), to exploit water resources at will. In all natural lakes and reservoirs changes occur in the water quality parameters as it relates to chemical nutrients, temperature and turbidity over time. These changes are collectively referred to as "Reservoir Ageing", of which sedimentation and eutrophication are primary. Reservoir Ageing has consequences which adversely affect and defeat many of the intended uses of the …

Estimating Cost Efficiencies Of Propane Use In Broiler Production: Case Study From Savoy, Arkansas And Trnaca Pri Laborci, Slovak Republic, Zuzana Petrikova

Graduate Theses and Dissertations

This study focuses on analyzing the common practice of U.S. broiler farmers to operate on cash basis instead open credit lines for operating cost of propane gas for heating. Data for analysis were taken over from U.S. ABRF at Savoy and Slovak Farm Univerza at Trnava pri Laborci. Predicting the propane gas usage and propane gas cost was analyzed using the OLS model. It describes impact of selected factors on gas usage and cost. The overall purpose of the thesis is to find out which approach from designed scenarios is more economically efficient for farmer: (a) to pre-purchase propane gas …

Limiting Behavior Of Nondeterministic Fillings Of The Torus By Colored Squares, Pablo Rosell Gonzalez

Graduate Theses and Dissertations

In this work we study different dynamic processes for filling tori and n×∞ bands with edge-to-edge black and white squares at random. First we present a simulation for the Random Sequential Adsorption (RSA) with nearest-neighbor rejection on n×n tori. We are interested in the ratio of black to total tiles once the domain is saturated for large domains. Next we study the annealing process. Given a random excited tiling of an n×n torus, we show that as t→∞ the system reaches a stable state in which no tile is excited. This stable state can either be a tiling whose tiles …

Review Of Science For Science Librarians: Graphene, Kathleen A. Lehman

University Libraries Faculty Publications and Presentations

Graphene is, in many ways, a simple substance. Made of a single atomic layer of graphite, graphene has emerged as a material providing many surprises and having immense scientific and industrial potential. In 2010, scientists Andre K. Geim and Konstantin S. Novoselov received the Nobel Prize in Physics for their isolation of graphene and for their research pertaining to the ultrathin material. In his presentation speech, Professor Per Delsing described how we all have made graphene each time we write with a pencil: microscopic bits of graphite and graphene flake away as the pencil moves across the paper (Delsing 2010). …

An Introductory Educational Board Game For Use In Early Computer Science Education, Tyler Moore

Computer Science and Computer Engineering Undergraduate Honors Theses

Early computer science education should be necessary in high school curricula, but often it becomes inextricably linked to the act of programming instead of the study of the principles of computation. In order to divest computer science from programming a new teaching medium is needed, and early research into games as teaching tools shows some positive results when used properly. In order to find a better way to teach early computer science concepts I have designed and implemented a board game which illustrates and defines a few necessary computer science terms and mechanics. I had reasonable success in the classroom, …

Portable Network Analyzer, Tyler Warren

Computer Science and Computer Engineering Undergraduate Honors Theses

With networks expanding into all areas of business, both network and security engineers are finding it more difficult to attend directly to issues. In many cases, a physical presence is still necessary on site to troubleshoot and identify issues, but on site, even carrying a bulky laptop is a hindrance. With today's advances in embedded systems, the answer to this problem is presented. A device running an embedded Computer on Module was built with a portable footprint, in both size and power requirements. A device of this type running an operating system like Linux is a powerful tool. In this …

Parallelizing Scale Invariant Feature Transform On A Distributed Memory Cluster, Stanislav Bobovych

Computer Science and Computer Engineering Undergraduate Honors Theses

Scale Invariant Feature Transform (SIFT) is a computer vision algorithm that is widely-used to extract features from images. We explored accelerating an existing implementation of this algorithm with message passing in order to analyze large data sets. We successfully tested two approaches to data decomposition in order to parallelize SIFT on a distributed memory cluster.

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 …

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 …

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 …

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, …

An Analysis Of The Stability And Transport Of Co2 On Mars And Iapetus: Increasing Accuracy Via Experiments And Photometry, David Garrison Blackburn

Graduate Theses and Dissertations

Volatile transport of carbon dioxide is most relevant on two planetary bodies in our solar system: Mars and Iapetus. We experimentally measured the sublimation rate of CO2 ice under simulated martian conditions and developed a model based on our experimental results. We experimentally verified that solar irradiance is the primary control for the sublimation of CO2 ice on the martian poles with the amount of radiation striking the surface being controlled by variations in the optical depth, ensuring the formation and sublimation of the seasonal cap. Our model, supported by comparison of MGS-MOC and MRO-HiRISE images, shows that ~ 0.4 …

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 …}

New Interfacial Nanochemistry On Sensory Bioscaffold-Membranes Of Nanobelts, Feng Chen

Graduate Theses and Dissertations

Nanostructured bioscaffolds and biosensors are evolving as popular and powerful tools in life science and biotechnology, due to the possible control of their surface and structural properties at the nm-scale. Being seldom discussed in literature and long-underexploited in materials and biomedical sciences, development of nanofiber-based sensory bioscaffolds has great promises and grand challenges in finding an ideal platform for low-cost quantifications of biological and chemical species in real-time, label-free, and ultrasensitive fashion. In this study, titanate nanobelts were first of all synthesized, from hydrothermal reactions of a NaOH (or KOH solution) with TiO2 powder, to possess underexploited structure and surface …

Profiles In Science: Stephen Hawking, Kathleen A. Lehman

University Libraries Faculty Publications and Presentations

While Stephen Hawking’s early academic career lacked focus, the development of motor neuron disease straining against his hopes for a fulfilling life pulled the young scientist’s work together. He has since become the world’s most famous scientist due, in part, to his strong belief that science should be accessible to the general public. Hawking has published frequently for the academic community but has also published for the lay reader. His life has been recorded and examined by several biographers. This paper gives an overview of Hawking’s early life, academic career, his academic and popular publications, as well as a few …

Phosphorus Release From Bottom Sediments At Lake Wister, Oklahoma, Summer 2010, B.E. Haggard, J.T. Scott

Arkansas Water Resources Center Technical Reports

A previous reservoir model of Lake Wister, Oklahoma suggested that internal P sources were dominant, and that a watershed management plan need not be developed to address external sources. The objectives of this study were to collect intact sediment cores from three sites at Lake Wister and measure sediment O₂ demand (SOD) and soluble reactive P (SRP) release to the overlying water during lab incubations under quiescent conditions. The measured SOD rates were between 9.9 and 22.6 mg m⁻² hr⁻¹ on average across the three sites, where the shallow headwaters site had the least SOD. The SRP release rates were …

Boundary Condition On Electron Temperature For Antiforce Current Bearing Waves, M. Hemmati, W. P. Childs, D. C. Waters, J. D. Counts, J. K. Schmitt

Journal of the Arkansas Academy of Science

In our investigation of breakdown waves, we apply a one-dimensional, three-component, steady-state fluid model. The wave is considered to be shock fronted and the electrons are assumed to be the main element in propagation of the wave. In our fluid model, the electron gas temperature is assumed to be large enough to sustain the wave motion. Our set of fluid equations is composed of the equations of conservation of mass, momentum and energy plus the Poisson’s equation. This investigation involves breakdown waves for which a large current exist in the vicinity of the wave front. Existence of current behind the …

Implementing A Food Waste To Compost Program At The University Of Arkansas: An Economic Feasibility Analysis, Zoe Teague

Inquiry: The University of Arkansas Undergraduate Research Journal

The University of Arkansas Fayetteville (UAF) is actively pursuing ways to increase sustainability on campus. Through the establishment of the Sustainability Council and campus centers, multiple projects are attempting to reduce the carbon footprint at UAF. One particular study is designed to eliminate food waste on campus through composting. The purpose of this study was to evaluate and project the economic savings of implementing a food waste composting system using Earth Tubs. Earth Tubs are an in-vessel electrical composting system capable of diverting up to 150 pounds of organic material daily with minimal odor. Results suggest that composting food waste …

Effects Of Annealing On The Electronic Transitions Of Zns Thin Films, S. S. Chiad, W. A. Jabbar, N. F. Habubi

Journal of the Arkansas Academy of Science

Thin films of zinc sulphide were prepared using a flash evaporation technique. The obtained thin films were subjected to heat treatment to investigate the effect of annealing on the transmittance spectrum and the electronic transitions. It has been found that annealing affected the transmission spectrum and caused an increase in the direct optical band gap. The optical parameters, oscillator energy E0 and dispersion energy Ed were determined using the Wemple DiDomenico single oscillator model. The optical energy gap obtained from the Wemple and DiDomenico model was in good agreement with the optical energy gap proposed by the Tauc theory.