Physical Sciences and Mathematics Commons^™

Strong Evidence For The Density-Wave Theory Of Spiral Structure From A Multi-Wavelength Study Of Disk Galaxies, Hamed Pour-Imani

Graduate Theses and Dissertations

The density-wave theory of spiral structure, though first proposed as long ago as the mid-1960s by C.C. Lin and F. Shu (Lin & Shu, 1964; Bertin & Lin, 1996; Shu, 2016), continues to be challenged by rival theories, such as the manifold theory. One test of these theories which has been proposed is that the pitch angle of spiral arms for galaxies should vary with the wavelength of the image in the density-wave theory, but not in the manifold theory. The reason is that stars are born in the density wave but move out of it as they age. In …

Seismic Facies Mapping For Source Rock Distribution Of The Rakopi Formation In Deep-Water Taranaki Basin, New Zealand, Sidney W. Mahanay

Graduate Theses and Dissertations

The Taranaki Basin is located off the coast of the north island of New Zealand and is currently the only producing basin in New Zealand. Hydrocarbon accumulation in the Tui, Maari, and Maui fields is sourced to the Late Cretaceous and Paleogene units. Exploration of these units has extended from the continental shelf of the Taranaki Basin into the deep-water to the northwest. The Romney 3D survey and Romney–1 well are some the first public exploration projects to supply data from this area. The objective of this study is to estimate source rock quality and distribution of the Rakopi Formation …

Opto-Thermal Characterization Of Plasmon And Coupled Lattice Resonances In 2-D Metamaterial Arrays, Vinith Bejugam

Graduate Theses and Dissertations

Growing population and climate change inevitably requires longstanding dependency on sustainable sources of energy that are conducive to ecological balance, economies of scale and reduction of waste heat. Plasmonic-photonic systems are at the forefront of offering a promising path towards efficient light harvesting for enhanced optoelectronics, sensing, and chemical separations. Two-dimensional (2-D) metamaterial arrays of plasmonic nanoparticles arranged in polymer lattices developed herein support thermoplasmonic heating at off-resonances (near infrared, NIR) in addition to regular plasmonic resonances (visible), which extends their applicability compared to random dispersions. Especially, thermal responses of 2-D arrays at coupled lattice resonance (CLR) wavelengths were comparable …

The Occurrence Of The Greta Sandstone, Frio Formation (Late Oligocene), Texas Gulf Coastal Plain, Sean C. Kincade

Graduate Theses and Dissertations

The Greta sandstone is an informal lithostratigraphic unit of the upper Frio Formation (Oligocene) that occurs across the Texas Gulf Coastal Plain. The Greta sandstone has been known to geologists since it was first drilled in the 1930’s, yet there has been very little research into this un-depleted and overlooked reservoir. This study provides insights into the lateral distribution and reservoir facies of the Greta sandstone. The unit represents an aggradational to transgressive barrier sandstone package grading up to mud-rich open marine inner shelf deposits. The interval is easily recognizable in well logs based on its strong SP and Gamma-ray …

Comparative Microbial Community Dynamics In A Karst Aquifer System And Proximal Surface Stream In Northwest Arkansas, Josue Rodriguez

Graduate Theses and Dissertations

Northwest Arkansas has well-developed karst systems, with numerous sinking streams and springs. Karst conduits make it easy for contaminants to enter groundwater systems, degrading the water quality and destroying fragile karst ecosystems. With the increase of urbanization, potential threats in the form of fecal contamination may prove to be more of a problem. The purpose of this research is to compare the difference between microbial communities within two different settings, a karst aquifer and a surface stream. The microbial communities within Blowing Spring Cave and Little Sugar Creek were detected and identified in water and sediment samples. Samples were also …

Proposed Astm Standard For The Stokoe-Type Resonant Column Torsional Shear Device, Anh Tuan Tran

Graduate Theses and Dissertations

Resonant Column Torsional Shear (RCTS) testing has become one of the most commonly used methods for determining laboratory soil stiffness and soil damping. The RCTS test has been accepted and is commonly utilized during the permitting of new nuclear facilities. However, there is still no available public standard for performing RCTS tests using the Stokoe-type device. Therefore, an ASTM standard for calibration and performance of RCTS tests using the Stokoe-type RCTS device is presented herein. Data collected using the Stokoe-type RCTS devices at the University of Arkansas (UofA) and at the Norwegian Geotechnical Institute (NGI) also aided in the development …

Sustainability Of Utilizing Renewable And Nuclear Energy In Saudi Arabia Using Different Types Of Life Cycle Assessment, Kamel Almutairi

Graduate Theses and Dissertations

Evaluating the global environmental impacts of the current and future energy policies in Saudi Arabia using Life cycle assessment (LCA) method was the main objective of this dissertation. First, the attributional life cycle assessment (ALCA) framework was used to evaluate the Saudi’s air conditioning systems, as they are responsible for about 70% of the total Saudi residential electricity consumption. The ALCA’s results showed that the AC use phase produces the largest share of the environmental impact and the magnitude of the environmental impacts is influenced by the type of primary fuel used for electricity generation.

Emerging non-fossil sources of electricity …

Equations Of Multi-Rees Algebras, Babak Jabbar Nezhad

Graduate Theses and Dissertations

In this thesis we describe the defining equations of certain multi-Rees algebras. First, we determine the defining equations of the multi-Rees algebra $R[I^{a_1}t_1,\dots,I^{a_r}t_r]$ over a Noetherian ring $R$ when $I$ is an ideal of linear type. This generalizes a result of Ribbe and recent work of Lin-Polini and Sosa. Second, we describe the equations defining the multi-Rees algebra $R[I_1^{a_1}t_1,\dots,I_r^{a_r}t_r]$, where $R$ is a Noetherian ring containing a field and the ideals are generated by a subset of a fixed regular sequence.

Adapting To Sparsity And Heavy Tailed Data, Mohamed Abdelkader Abba

Graduate Theses and Dissertations

The Lasso and the Horseshoe, gold-standards in the frequentist and Bayesian paradigms, critically depend on learning the error variance. This causes a lack of scale invariance and adaptability to heavy-tailed data. The √ Lasso [Belloni et al., 2011] attempt to correct this by using the `1 norm on both the likelihood and the penalty for the objective function. In contrast, there is essentially no methods for uncertainty quantification or automatic parameter tuning via a formal Bayesian treatment of an unknown error distribution. On the other hand, Bayesian shrinkage priors lacking a local shrinkage term fails to adapt to the large …

Flow Regime Influences On Stream And Riparian Soil Carbon Dynamics In The Ozark Highlands And Boston Mountains Of Arkansas, Allyn Dodd

Graduate Theses and Dissertations

The natural flow regime exerts primacy over lotic ecosystem patterns and processes. However, little work has examined the influence of flow regime on instream and riparian carbon (C) dynamics in minimally-impacted, temperate forested systems. To date, most research efforts have focused on characterizing C movement and transformations across biomes and land use categories; however, flow regime represents an overlooked, finer level of detail that may drive differences in ecosystem function. My dissertation objective was to measure C fixation and movement within and across multiple environmental spheres (e.g. within stream channels, between stream surfaces and the atmosphere, and from riparian soils …

Privacy-Preserving Photo Taking And Accessing For Mobile Phones, Ang Li

Graduate Theses and Dissertations

Today, we are living in environments that are full of cameras embedded in devices such as smart phones and wearables. These mobile devices and as well as apps installed on them are designed to be extremely convenient for users to take, store and share photos. In spite of the convenience brought by ubiquitous cameras, users' privacy may be breached through photos that are taken and stored with mobile devices. For example, when users take a photo of a scenery, a building or a target person, a stranger may also be unintentionally captured in the photo. Such photos expose the location …

Theatrical Genre Prediction Using Social Network Metrics, Manisha Shukla

Graduate Theses and Dissertations

With the emergence of digitization, large text corpora are now available online that provide humanities scholars an opportunity to perform literary analysis leveraging the use of computational techniques. This work is focused on applying network theory concepts in the field of literature to explore correlations between the mathematical properties of the social networks of plays and the plays’ dramatic genre, specifically how well social network metrics can identify genre without taking vocabulary into consideration. Almost no work has been done to study the ability of mathematical properties of network graphs to predict literary features. We generated character interaction networks of …

Conformationally-Controlled Late-Stage Modifications For Sar Studies Of The C-3-Glcp Moiety Of Ipomoeassin F, Lucas Whisenhunt

Graduate Theses and Dissertations

The resin glycoside, ipomoeassin F has been shown to be extremely potent against multiple cancer lines (IC50 = 4.2-36 nM). However, the mechanism of action of this potent and complex natural product is still not fully understood. The α,β-unsaturated esters of the glucosyl moiety have been shown to be vital for the overall cytotoxicity of ipomoeassin F. Nevertheless, the importance of the tigloyl ester of the glucosyl moiety is still largely unknown. This work aimed to study the pharmacophore importance of the tigloyl ester by creating, an efficient, scalable, and flexible synthesis route for various analogs. The 18-linear step synthesis …

Evaluating Climate Change Policy Through The Endangered Species Act, Richie Donahou

Graduate Theses and Dissertations

This research sets out to address a growing knowledge gap of climate change science in regards to the state of Arkansas. Within the coming chapters, the goal of this research is to examine climate data and to identify if any evidence of climate change can be detected and what are the policies in place to adapt to these potential changes. Furthermore, the scope of this research will be narrowed to a few counties over the southwest Arkansas, and a specific endangered species, the Leopard Darter. Upon examination of previous environmental and ecological climate change related research it became clear that …

Methane Emissions From Rice Production On A Silt-Loam Soil In Arkansas, Joshua Jeffry Humphreys

Graduate Theses and Dissertations

Methane (CH4) emissions from rice (Oryza sativa L.) production are a source of concern in the environmental and agricultural communities. New and/or revised agronomic methodologies will be needed to identify production practice combinations that reduce CH4 emissions without decreasing yields. The objective of this multi-year study was to evaluate the effects of water management (i.e., full-season flood and mid-season drain) (2015), cultivar (i.e., pure-line cultivar ‘LaKast’ and the RiceTec hybrid “XP753”) (2015), soil organic matter (SOM) concentration (2016), and tillage [conventional tillage (CT) and no-tillage (NT)] and urea-based fertilizers [N-(n-butyl) thiophosphoric triamide (NBPT)-coated urea and non-coated urea] (2017) on CH4 …

Stratigraphic Evaluation Of The St. Joe-Boone Boundary Interval, Kinderhookian-Osagean Series, Lower Mississippian System, Tri-State Region, Southern Midcontinent, Forrest Dalton Mcfarlin

Graduate Theses and Dissertations

The Lower Mississippian interval comprises a single, third-order, eustatic cycle subdivided lithostratigraphically into the St. Joe Limestone (Hopkins 1893) and overlying Boone Formation (Branner 1891, Simonds 1891) with type areas in northern Arkansas. Coeval, homotaxial limestones occur in adjacent southwestern Missouri and northeastern Oklahoma. Missouri formation names for the St. Joe interval are recognized in Arkansas as members (ascending order): Bachelor, Compton, Northview, Pierson. The Boone interval in Missouri is represented by the (ascending order): Reeds Spring, Elsey, Burlington-Keokuk undifferentiated, but utilization of those names in Arkansas is problematic. in northern Arkansas, the Boone Formation is subdivided into informal lower …

What Can I Do As A Student To Make A Positive Impact On The Environment?, Tammy Guthrie, Greg Herzig, Kathy Prophet, Cassie Kautzer

Middle School Lesson Plans

Students discover ways they can make a positive impact on the environment.

An Agent-Based Approach To Simulating The Minimum Wage Market, Luke Snyder

Computer Science and Computer Engineering Undergraduate Honors Theses

This paper seeks to identify and describe the economic impacts of adjusting the minimum wage on employment. The approach taken is constructing an agent-based simulation using the well-known software suite NetLogo. The simulation models business and consumer behavior through a set of governing economic principles, yet also provides randomization to more accurately account for occasional outliers and human irrationality. The results of the simulation indicate relatively small changes in employment among minimum wages between $7.25 and $10.00, with a gradual decrease thereafter.

Investigating Initial Interactions Between Silver Nanoparticles And Wastewater, Casey Gibson

Biological and Agricultural Engineering Undergraduate Honors Theses

The use of nanoparticles (NPs) has increased exponentially in the last 15-20 years, especially in the consumer market. NPs are currently found in over 1800 commercial products, including cosmetics, clothing, packaging, and toys. As a result, NPs can enter the environment via wastewater (WW) streams, leading to new challenges in WW treatment. This study focuses on the initial fate of silver nanoparticles (AgNPs) in WW. The AgNP interaction including aggregation and dissolution in both synthetic and real WW were studied. Real WW was collected from the primary-clarifier, secondary-clarifier, and effluent WW streams at two local WW treatment plants (Westside and …

Performance Assessment Of Solid State Anaerobic Digestion Of Poultry Litter, Mason Puckett

Biological and Agricultural Engineering Undergraduate Honors Theses

The disposal of poultry litter can exert an economic and environmental burden to the agriculture community. As a result, it is desirable to reduce the amount of waste and recover resources from the waste. This study focuses on the construction and preliminary testing of a laboratory scale (20 L) solid state anaerobic digester (AD) fed with dry poultry litter. Glucose was added in addition to the poultry litter to achieve the appropriate C:N ratio to support the growth of anaerobic microorganisms. The AD was first fed every 4 days at 4 g VS/L/feeding for 24 days, rested (no feeding) for …

A Proposed Approach To Hybrid Software-Hardware Application Design For Enhanced Application Performance, Alex Shipman

Graduate Theses and Dissertations

One important aspect of many commercial computer systems is their performance; therefore, system designers seek to improve the performance next-generation systems with respect to previous generations. This could mean improved computational performance, reduced power consumption leading to better battery life in mobile devices, smaller form factors, or improvements in many areas. In terms of increased system speed and computation performance, processor manufacturers have been able to increase the clock frequency of processors up to a point, but now it is more common to seek performance gains through increased parallelism (such as a processor having more processor cores on a single …

Characterization Of Bacteriorhodopsin And Halorhodopsin Reconstituted In Lipid Bilayer Membranes, Joel Domkam Kamwa

Graduate Theses and Dissertations

Motivated to produce electricity with photon activated ion pumps, the main purpose of this work was to characterize the photosynthetic membrane proteins bacteriorhodopsin (proton pump) and halorhodopsin (chloride pump). The proteins were re-suspended in lipid bilayers. For this work, an experimental set-up was built which included: chambers for lipid bilayer formation and characterization, lasers for ion pump activation, and an AxoPatch electrophysiology system for small photocurrent measurement. Lipid bilayer membranes were formed using mostly folding method: folding two monolayers together. The membranes were characterized by their resistance, capacitance, and generated photocurrent. Photocurrent was generated upon illumination of lipid-protein membranes with …

Tamscript - High Level Programming Interface For The Abstract Tile Assembly Model, Perry Mills

Computer Science and Computer Engineering Undergraduate Honors Theses

This paper describes a programming interface, TAMScript, for use with the PyTAS simulator. The interface allows for the dynamic generation of tile types as the simulation progresses, with the goal of reducing complexity for researchers. This paper begins with an introduction to the PyTAS software and a description of the 3D model which it simulates. Next, the changes made to support a dynamic generation scheme are detailed, and some of the potential benefits of this scheme are outlined. Then several of the example scripts which have been written using the TAMScript interface are reviewed. Finally, the potential for future research …

Non-Covalent Functionalization Of Graphene Films For Uniform Nanoparticle Deposition Via Atoic Layer Deposition, Ty Seiwert

Mechanical Engineering Undergraduate Honors Theses

Graphene functionalized with platinum (Pt) and palladium (Pd) has proven to be highly effective as a hydrogen sensor. Deposition methods such as Atomic layer deposition (ALD) can be further enhanced by pretreating the graphene with a non-covalent surfactant prior to nanoparticle deposition. In this study, graphene-based sensing devices will be fabricated by ALD deposition. The graphene will be non-covalently functionalized using sodium dodecyl sulfate (SDS) anionic surfactant prior to ALD deposition. The aim of this study is to test the deposition pattern achieved by varying the amount of time that graphene is treated with the SDS surfactant. Initially, ALD deposition …

Lithium And The Foreseeable Future, Paolo Vargas

Mechanical Engineering Undergraduate Honors Theses

This paper aims to clarify the uncertainties regarding worldwide lithium resource availability in the years to come. Previous studies made on the subject are presented with some ambiguity and this work intends to fill the gaps. The information and data presented throughout this script with respect to global lithium resources and reserves are mostly based on data released by the United States Geological Survey (USGS). Lithium resource availability in the future is a point of paramount significance primarily for the automotive, portable electronics, and the power generation industry. Since, a change of supply would ultimately affect the price of lithium, …

Dynamic 3d Network Data Visualization, Brok Stafford

Computer Science and Computer Engineering Undergraduate Honors Theses

Monitoring network traffic has always been an arduous and tedious task because of the complexity and sheer volume of network data that is being consistently generated. In addition, network growth and new technologies are rapidly increasing these levels of complexity and volume. An effective technique in understanding and managing a large dataset, such as network traffic, is data visualization. There are several tools that attempt to turn network traffic into visual stimuli. Many of these do so in 2D space and those that are 3D lack the ability to display network patterns effectively. Existing 3D network visualization tools lack user …

Computational Complexity Of Determining The Rigidity Of Ftam Assemblies, Ian Perkins

Computer Science and Computer Engineering Undergraduate Honors Theses

In this paper, we discuss a tile-based self-assembly model called the Folding Tile Assembly Model (FTAM). We briefly define what makes the FTAM unique in its ability to have folding 2D tiles. We also discuss the difficulty of determining the computational complexity of certain FTAM properties despite it being simpler for less dynamic models. Specifically, we discuss the property of rigidity in FTAM assemblies by devising a simple definition of rigidity, so that it is easier to determine its complexity. We use a reduction between an assembly and a 3SAT instance along with a series of proofs to give a …

Soil Organic Carbon And Mineralization Rates At The Woolsey Wet Prairie Mitigation Site In Fayetteville, Arkansas, Zachary Tipton

Crop, Soil and Environmental Sciences Undergraduate Honors Theses

Atmospheric carbon dioxide (CO2) levels are higher than ever recorded, surpassing 400 ppm in 2013, from a pre-industrial revolution level of around 280 ppm. Researchers have been looking at methods to mitigate high CO2 levels in the atmosphere, including promoting carbon sequestration in soils. Carbon sequestration is the process where CO2 is naturally or artificially transferred out of the atmosphere and stored in the ocean, plant biomass, soils, and geologic formations. Seemingly contradictory to the notion of carbon sequestration, is the use of fire as a management treatment for the restoration of native prairie grass ecosystems. Fire combusts plant biomass …

Usability Of Sound-Driven User Interfaces, Zachary T. Roth, Dale R. Thompson

Computer Science and Computer Engineering Undergraduate Honors Theses

The model for interacting with computing devices remains primarily focused on visual design. However, sound has a unique set of advantages. In this work, an experiment was devised where participants were tasked with identifying elements in an audio-only computing environment. The interaction relied on mouse movement and button presses for navigation. Experiment trials consisted of variations in sound duration, volume, and distinctness according to both experiment progress and user behavior. Participant interactions with the system were tracked to examine the usability of the interface. Preliminary results indicated the majority of participants mastered every provided test, but the total time spent …

Interpretation And Fracture Characterization Of Early-Cretaceous Buda Limestone Formation Using Post-Stack 3d Seismic Data In Zavala County, Texas, Andrey Smirnov

Graduate Theses and Dissertations

The Buda Limestone is a naturally fractured Early Cretaceous carbonate formation in south Texas which unconformably underlies the Eagle Ford Shale. Matrix porosity of the Buda is less than 6%, therefore natural fractures improve the potential for commercial hydrocarbon production from this tight limestone formation. This presents a challenge for producers to identify these zones using well log and post stack 3D seismic data typically available to medium or small exploration companies. This project provides a workflow based on well log analysis tied to seismic acoustic impedance (AI) inversion to locate areas of probable natural fractures. Acoustic impedance inversion was …