Physical Sciences and Mathematics Commons^™

Economic Feasibility Of Aquaponics In Arkansas, Leah Ashley English

Graduate Theses and Dissertations

Concerns regarding population growth and resource scarcity have led to a recent renaissance of food production research. Over the past few decades, scientists have discovered new and innovative methods for growing food that, cumulatively, may hold the key to efficiently and sustainably feeding an ever-increasing world population. One method, known as aquaponics, has shown promise as being a sustainable solution for producing food locally in all parts of the world. Although many studies have shown aquaponic food production to be technically feasible, there are relatively few studies concerning the economic feasibility of aquaponics in various regions. To determine whether aquaponics …

Reservoir Characterization And Depositional System Of The Atokan Grant Sand, Fort Worth Basin, Texas, Victoria Wood

Graduate Theses and Dissertations

The Atokan Grant Sands are a tight gas sand play that would add new reserves to the Fort Worth Basin. The Fort Worth Basin is located in north-central Texas just west of Dallas, Texas. Within the basin, the study area consists of Denton, Wise, Tarrant, and Parker Counties in Texas. The basin is bounded to the north by the Red River Arch, to the west by the Bend Arch, to the south by the Llano uplift, to the east by the Ouachita structural front, and to the northeast by the Muenster Arch. The Grant Sands are approximately 1,500 ft stratigraphically …

Paddling A Trail, Erin Jennings Gilleece

Graduate Theses and Dissertations

Paddling A Trail documents construction of the first water trail in Arkansas. The 15 minute film is narrated by Arkansas Canoe Club Conservation Chair Debbie Doss. It follows Doss, and other volunteers as they mark the Wattensaw Bayou Trail in Hazen, Arkansas. The film is co-narrated by Kristen Bartlow of the Arkansas Game and Fish Commission. The footage was shot over three days, in two different locations. These were the White River in Northwest Arkansas and Wattensaw Bayou in Hazen, AR. The film illustrates the positive role trails can have on the environment and local economies. More importantly, the film …

Evaluation Of Conservation Practices Through Simulation Modeling And Tool Development, Gurdeep Singh

Graduate Theses and Dissertations

For the first objective, predicted impacts of selected Mississippi River Basin Initiative (MRBI) conservation practices (CPs) on sediment and nutrient loss were assessed. The study area was L’Anguille River Watershed (LRW), a priority focus watershed of the MRBI program and the simulated CPs were filter strip, critical area planting, grade stabilization structure, irrigation land leveling, irrigation pipeline, irrigation water management, and nutrient management. The Soil and Water Assessment Tool (SWAT) model was calibrated (1998 – 2005) and validated (2006 – 2012) for flow, sediment, total phosphorus (TP), and nitrate-nitrogen (NO3-N) at the Colt site (503 sq. km. drainage area) and …

Influence Of Shelling Temperature And Time On The Optical And Structural Properties Of Cuins2/Zns Quantum Dots, Colette Robinson

Graduate Theses and Dissertations

CIS/ZnS core/shell QDs are an important class of nanomaterials for optoelectronic, photovoltaic and photoluminescence applications. They consist of lower toxicity materials than the prototypical II-VI Cd-based QDs and show long fluorescence lifetimes, which generates prospective in biological imaging applications. It is vital to develop reproducible synthetic methods for this new class of nanomaterials in order to maintain small sizes with high QYs. CIS core QDs have been shelled with ZnS at various temperatures from 90-210°C for reaction times ranging from 20-140 minutes to examine the role of thermodynamics and kinetics on the shell growth. Using HR-TEM and ICP-MS, it was …

Hydrology-Biology Response Relationships In The Ozark Highlands, Dustin Thomas Lynch

Graduate Theses and Dissertations

I examined flow-ecology relationships among stream communities in the Ozark Highlands, USA. I sampled fish, crayfish, and benthic macroinvertebrates during two consecutive summers, including a drought year (2012) and a flood year (2013). Biological response variables related to community structure were assessed via two different statistical methods: an Information Theoretic approach relating response variables to a priori selected predictor variables incorporating hydrology, habitat, geomorphology, and water quality, and canonical ordination using forward selection to relate these same response variables to a large assortment of hydrologic metrics. In addition to assessing metrics related to predicted natural flow, flow alteration at gaged …

Photochemistry Of A Series Of Weakly Coupled Dinuclear Ruthenium(Ii) Complexes, Latisha Michelle Puckett

Graduate Theses and Dissertations

An improved synthetic method was developed for symmetric ruthenium(II) polypyridine complexes with the form L2Ru(diphen)RuL2. The scope of the reaction was investigated in regards to the ligands, bridging ligands, and starting materials. Several ligands were successful in the synthesis, including 2,2’-bipyridine (bpy), 4,4’-dimethyl-2,2’-dipyridyl (dmb), 1,10-phenanthroline (phen), 4,7-diphenyl-1,10-phenanthroline (dpphen), and 3,4,7,8-tetramethyl-1,10-phenanthroline (tmphen). Ligands that did not react to form symmetric dimeric complexes were 2,2’-bipyrazine, bpz, and 2,2’-bipyrimidine, bpm.

Dpp, 2,3-bis(2-pyridyl)-pyrazine, effectively replaced diphen as the bridging ligand to produce (phen)2Ru(dpp)Ru(phen)24+. However, replacing the [Ru(CO)2Cl2]n with Ru(DMSO)4Cl2 did not prove successful. The newly developed synthesis was also applied to the synthesis of …

Neural Decomposition Of Time-Series Data For Effective Generalization, Luke Godfrey

Graduate Theses and Dissertations

We present a neural network technique for the analysis and extrapolation of time-series data called Neural Decomposition (ND). Units with a sinusoidal activation function are used to perform a Fourier-like decomposition of training samples into a sum of sinusoids, augmented by units with nonperiodic activation functions to capture linear trends and other nonperiodic components. We show how careful weight initialization can be combined with regularization to form a simple model that generalizes well. Our method generalizes effectively on the Mackey-Glass series, a dataset of unemployment rates as reported by the U.S. Department of Labor Statistics, a time-series of monthly international …

The Mass-Pitch Angle Relation For Three High Redshift Active Galaxies Selected From The Goods Field, John Adam Hughes

Graduate Theses and Dissertations

As we continue to investigate and ponder the heavens, we have come to realize the presence of highly energetic gravitational wells at the center of all galaxies. These supermassive black holes at a galaxies nucleus formed in the company of the other features making up the galaxy, particularly spiral arms. With nearby galaxies showing a relationship between the spiral arm pitch angle and that central mass, here we push that relationship out to distances of redshift one. With three galaxies at this distance we find that they also hold to the same relationship of tighter spiral arms corresponding to more …

Probabilistic Graphical Modeling On Big Data, Ming-Hua Chung

Graduate Theses and Dissertations

The rise of Big Data in recent years brings many challenges to modern statistical analysis and modeling. In toxicogenomics, the advancement of high-throughput screening technologies facilitates the generation of massive amount of biological data, a big data phenomena in biomedical science. Yet, researchers still heavily rely on key word search and/or literature review to navigate the databases and analyses are often done in rather small-scale. As a result, the rich information of a database has not been fully utilized, particularly for the information embedded in the interactive nature between data points that are largely ignored and buried. For the past …

Swat Model Simulation Of Bioenergy Crop Impacts On Water Quality In Cache River Watershed, Eeshan Kumar

Graduate Theses and Dissertations

Energy security through increased biofuel production is one of the components of the Energy Independence and Security Act (EISA) 2007. As per EISA 2007 mandate, appropriate independent research institutes are required to assess concerns to natural biodiversity due to biofuel production and report it to the Congress through the Environment Protection Agency (EPA). Planners, researchers, and agencies concerned with environmental regulations, ideally, would like to have location-specific information about the impacts for developing appropriate management interventions. This study examines long-term impacts on water quality in response to targeted (i.e. marginal lands) production of biofuel crops by setting up two SWAT …

Stratigraphic And Structural Analysis Of Middle Atoka Formation In Aetna Gas Field, Franklin, Johnson And Logan Counties, Arkansas, Ikramuddin Bahram

Graduate Theses and Dissertations

Arkoma basin is a prolific natural gas basin. The defining feature of this basin is the Atoka Formation that was deposited in the early-middle Pennsylvanian. The Atoka is held equivalent to the tectonic and structural evolution of the basin. This study focuses on one of the many gas fields in the Arkoma Basin in Arkansas to assess the stratigraphic and structural evolution that the strata in this particular field display.

Aetna Gas Field extends from T. 8N. R. 27 W to T. 9 N, R. 27 W and T. 8 N, R. 26 W to 8N, R. 27. Geographically, Aetna …

Dark Matter Halo Concentration And The Evolution Of Spiral Structure In N-Body, Barred Spiral Galaxies, Jazmin Esmeralda Berlanga Medina

Graduate Theses and Dissertations

Motivated by the evidence of relationships between pitch angle (the tightness of spiral arm structure in the disk), P, and various indicators of central mass concentration, as well as the theoretical relationship between halo mass concentration and the density of visible matter in the central part of the galaxy, we look at a possible relationship between P and cvir (the virial concentration of the dark matter halo) in N-body simulations of barred, spiral galaxies. We also look at the evolution of pitch angle over time in higher temporal resolution than any data currently available in the literature. We find that …

Evaluating The Intrinsic Similarity Between Neural Networks, Stephen Charles Ashmore

Graduate Theses and Dissertations

We present Forward Bipartite Alignment (FBA), a method that aligns the topological structures of two neural networks. Neural networks are considered to be a black box, because neural networks contain complex model surface determined by their weights that combine attributes non-linearly. Two networks that make similar predictions on training data may still generalize differently. FBA enables a diversity of applications, including visualization and canonicalization of neural networks, ensembles, and cross-over between unrelated neural networks in evolutionary optimization. We describe the FBA algorithm, and describe implementations for three applications: genetic algorithms, visualization, and ensembles. We demonstrate FBA's usefulness by comparing a …

Applications Of Cultural Theory And Empirical Analysis Of Sustainable Energy Policy Preferences In Arkansas, John Henry Kester Iii

Graduate Theses and Dissertations

The local policy arena is ripe for research on policy elite decisionmaking because where policy diffusion is concerned, previous studies focus on state-to-state and city-to-city dynamics. Therefore, there is a significant opportunity to expand understanding about the adoption of policies and policy diffusion at the local level. Identification of individual level determinants that signify policy adoption is a cornerstone to fostering this knowledge. This study examines such preference indicators found among policy elites in select Arkansas cities. For this research, the primary theoretical perspective for evaluating individual determinants is cultural theory, which has shown strong correlation to individual policy preference …

Modifying A Cow-Calf Biophysical Simulation Model For Analyses Of Alternative Enterprises, Jennifer L. Lutes

Graduate Theses and Dissertations

Cow-calf producers in the United States, tasked with providing beef calves for the beef industry, have had a multitude of difficulties to overcome in recent years. Producers in northwest Arkansas were negatively impacted by high hay prices coupled with low beef cattle market prices due to severe drought experienced in portions of 2010, 2011, and 2012. During this time they also faced high grain prices, due to a record low harvest, combined with portions of the corn harvest diverted from human and animal feed to ethanol production. Tight lending policies of this time, reminiscent of the housing market crash in …

Compounds Released From Biomass Deconstruction: Understanding Their Effect On Cellulose Enzyme Hydrolysis And Their Biological Activity, Angele Djioleu

Graduate Theses and Dissertations

The effect of compounds produced during biomass pretreatment on cellulolytic enzyme was investigated. Liquid prehydrolyzates were prepared by pretreating switchgrass using 24 combinations of temperature, time, and sulfuric acid concentration based on a full factorial design. Temperature was varied from 140°C to 180°C; time ranged from 10 to 40 min; and the sulfuric acid concentrations were 0.5% or 1% (v/v). Identified products in the prehydrolyzates included xylose, glucose, hydroxymethylfurfural (HMF), furfural, acetic acid, formic acid, and phenolic compounds at concentration ranging from 0 to 21.4 g/L. Pretreatment conditions significantly affected the concentrations of compounds detected in prehydrolyzates. When assayed in …

Available Nitrogen And Denitrification In Soil Altered By Ground Cover And Nutrient Source In An Organic Apple Orchard, Jade Nicole Ford

Graduate Theses and Dissertations

A shift in public demand towards more organic and locally produced fruit and vegetables has been occurring across the United States in recent years. A common practice in organic fruit production is the application of organic ground covers to supply nutrients while enhancing other soil properties. A need for research exists in the southern region of the U.S. examining the effects of regionally applicable ground cover and nutrient management on nitrogen availability and the microbial community to provide information to organic farmers in the region. Two studies were conducted to determine how 12 treatment combinations of four ground covers (compost, …

Modified Polysulfone Nanofiltration Membrane Synthesis For Hydraulic Fracturing Water Recycle, Blake Alexander Johnson

Graduate Theses and Dissertations

The use of hydraulic fracturing has resulted in significant increases in the yield of oil and natural gas, as water pumped into wells at high pressure cracks the formations and releases the hydrocarbons that are locked in the rocks. This process has created large volumes of brackish water that is very difficult to process and is often disposed of into injection wells. Suspended solids and some dissolved solids are more readily removed, but the multivalent ions found in certain salts can precipitate in a well and complicate the reuse of flowback in future hydraulic fracturing operations.

Nanofiltration, a membrane separation …

Thermodynamic Modeling Of Aqueous Geochemistry Of Chlorine Salts: Application To Stability And Habitability Of Liquid Brines On Mars, Amira Elsenousy

Graduate Theses and Dissertations

The WCL (Wet Chemistry Lab) instrument on board the Mars’s Phoenix Lander has identified the soluble ionic composition of the soil at the landing site. Two important ions were detected at the landing site; perchlorates (ClO4-) with a concentration of ~ 2.4 wt% and chlorides (Cl-) with a concentration of 0.54 wt%. Between chloride and perchlorate ions three other oxidized ions exist and called chlorine ions: hypochlorite ClO - (ox. state +1), chlorite ClO2- (ox. state +3) and chlorate ClO3- (ox. state +5). These oxidized ions might be existed as intermediate species on the surface of Mars but remained undetected. …

Defining The Potassium Nutritional Requirements And Distribution Among Plant Parts Of Representative Soybean Cultivars From Different Maturity Groups, Md. Rasel Parvej

Graduate Theses and Dissertations

The potassium (K) requirement of soybean [Glycine max (L.) Merr.] was investigated to determine whether cultivar sensitivity to K deficiency was affected by growth habit (determinate or indeterminate) and how cultivars from each growth habit accumulate and distribute K among plant structures. We also diagnosed K deficiency across reproductive growth stages (R2-6) using trifoliolate leaf- and petiole-K concentrations and at harvest (R8) using seed-K concentration. Soybean responded similarly to K deficiency in terms of yield, selected yield components, and seed-K concentration, regardless of growth habit. The yield loss from K deficiency was greatest on the middle to upper nodes of …

Calorimetry And Body Composition Research In Broilers And Broiler Breeders, Justina Victoria Caldas Cueva

Graduate Theses and Dissertations

Indirect calorimetry to study heat production (HP) and dual energy X-ray absorptiometry (DEXA) for body composition (BC) are powerful techniques to study the dynamics of energy and protein utilization in poultry. The first two chapters present the BC (dry matter, lean, protein, and fat, bone mineral, calcium and phosphorus) of modern broilers from 1 – 60 d of age analyzed by chemical analysis and DEXA. DEXA has been validated for precision, standardized for position, and equations and validations developed for chickens under two different feeding levels. These equations are unique to the machine and software in use. Research in broilers …

The Structural Analysis Of Enola And Greenbrier, Arkansas Earthquake Swarms: Cause And Effect?, Minella Majenu

Graduate Theses and Dissertations

Almost 20 years after the remarkable earthquake swarm of 1982, near the town of Enola, Arkansas, with more than 40,000 micro-earthquakes, another event revisited the same North-Central Arkansas region in 2001. Nine years later, in 2010, a huge swarm event shook the northern part of Faulkner County, around the city of Guy. The following year, this seismic swarm event apparently migrated southward towards the city of Greenbrier, with an increase in the number of yearly recorded events. A 13km previously unrecognized, NE trending Guy-Greenbrier basement fault was revealed as a result of these swarm events.

Within the vicinity of the …

Validation Of Soil-Test-Based Phosphorus And Potassium Fertilizer Recommendations For Rice And Soybean, Matthew Scott Fryer

Graduate Theses and Dissertations

The science of soil-testing for nutrient management and fertilizer recommendations is widely accepted among scientists and agronomists. Although this science is unsurpassed in predicting soil nutrient availability, soil-test interpretations are seldom validated. Major research objectives for irrigated soybean [Glycine max (L.) Merr.] and direct-seeded, delayed-flood rice (Oryza sativa L.) were to: i) validate the accuracy of Mehlich-3 soil-test P (STP) and K (STK) interpretations and ii) published critical tissue-P and -K interpretations in predicting the yield response to fertilizer at different significance levels (p≤0.05 to 0.25), iii) examine how seed nutrient concentrations are influenced by fertilization and crop response to …

Good Stein Neighborhood Bases For Nonsmooth Pseudoconvex Domains, Chizuko Iwaki

Graduate Theses and Dissertations

In 1979, Dufresnoy showed that the existence of a good Stein neighborhood base for Ω ⊂ℂⁿ implies that one can solve the inhomogeneous Cauchy-Riemann equations in C^∞(Ω̄), even if the boundary of Ω is only Lipschitz. In my thesis, I will show sufficient conditions for the existence of a good Stein neighborhood base on a Lipschitz domain satisfying Property (P).

Long-Term Effects Of Alternative Residue Management Practices On Near-Surface Soil Properties And Soybean Production In A Wheat-Soybean, Double-Crop System In Eastern Arkansas, Christopher Ryan Norman

Graduate Theses and Dissertations

Adoption of management practices that maintain or increase soil organic matter (SOM), which contains 58% carbon (C) on average, may help to mitigate climate change by sequestering atmospheric C. Therefore, the main objective of this study was to determine the long-term trends in SOM, soil C and nitrogen (N), bulk density, various soil chemical properties (i.e., pH, electrical conductivity [EC], and Mehlich-3-extractable nutrients) in the top 10 cm, and soybean yield as affected by residue burning (burning and non-burning), tillage (conventional and no-tillage), irrigation (irrigated and non-irrigated), and N-fertilization/residue level (high and low) in a wheat (Triticum aestivum L.)-soybean [Glycine …

Metal Mobilization In Groundwater, Bauxite, Ar, Steven Alexander Hamlin

Graduate Theses and Dissertations

The Wilcox Aquifer of Bauxite, AR contains bauxite ore deposits that may contribute heavy metals to groundwater. Twenty-four wells were sampled for aluminum, iron, manganese, zinc, lead, barium, nitrate, sulfate, sodium, alkalinity, calcium, magnesium, chloride, pH, total organic carbon, and total dissolved solids. A Wilcoxon Rank-Sum compared the similarity of the three geographic areas covered in the study. All parameters for wells in Bauxite and Sardis failed to reject the null hypothesis, signifying that wells all occupy the Saline Formation. 2/3rds of the parameters from BFI261 and the Bauxite region did not agree, suggesting the two areas do not occupy …

Static And Dynamical Properties Of Ferroelectrics And Related Material In Bulk And Nanostructure Forms, Zhigang Gui

Graduate Theses and Dissertations

Ferroelectrics (FE) and multiferroics (MFE) have attracted a lot of attentions due to their rich and novel properties. Studies towards FE and MFE are of both fundamental and technological importance. We use a first-principles-based effective Hamiltonian method, conventional ab-initio packages and linear-scale three-dimension fragment method to investigate several important issues about FE and MFE. Tuning the properties of FE and MFE films are essential for miniaturized device applications, which can be realized through epitaxial strain and growth direction. In this dissertation, we use the effective Hamiltonian method to study (i) BaTiO 3 films grown along the (110) pseudocubic direction on …

Automatic User Profile Construction For A Personalized News Recommender System Using Twitter, Shiva Theja Reddy Gopidi

Graduate Theses and Dissertations

Modern society has now grown accustomed to reading online or digital news. However, the huge corpus of information available online poses a challenge to users when trying to find relevant articles. A hybrid system “Personalized News Recommender Using Twitter’ has been developed to recommend articles to a user based on the popularity of the articles and also the profile of the user. The hybrid system is a fusion of a collaborative recommender system developed using tweets from the “Twitter” public timeline and a content recommender system based the user’s past interests summarized in their conceptual user profile. In previous work, …

Grass Finishing Systems For Lambs, Erin Leigh Smyth

Graduate Theses and Dissertations

There is strong interest in sustainably produced meat. Grass-fed lamb could fulfill this market by reducing off-farm inputs. The objective was to examine the effect of grass-finishing or minimal supplementation on performance of lambs in the southeastern US. Katahdin lambs born in October 2013 and 2014 and February 2014 were weaned in January 2014/2015 and May 2014, respectively. Lambs were blocked by gender (fall; winter included only ram lambs) and randomly assigned to receive no (NON) or grain co-product supplement (SUP; 15% CP) at 0.5% of BW/d. Lambs were rotationally grazed on predominantly grass. Body weight, fecal egg counts (FEC), …