Digital Commons Network^™

Geolocation Of Monitoring Wells Using Small Unmanned Aircraft Systems, Joel Deyoung

Graduate Theses and Dissertations

Groundwater monitoring wells are commonly installed on a property as part of an environmental investigation to observe hydrological subsurface conditions, facilitate the collection of groundwater samples, and predict the flow of groundwater across a site. In addition to their installation, monitoring wells should be surveyed or mapped as accurately as possible. Traditional surveying techniques have employed the use of global navigation satellite systems (GNSS) technologies or other surveying equipment. A common surveying approach is to use real-time kinematic (RTK) GNSS to accurately measure the coordinates of each monitoring well on the site.In recent years, drones, or small unmanned aircraft systems …

Computational Modeling Of Black Phosphorus Terahertz Photoconductive Antennas Using Comsol Multiphysics With Experimental Comparison Against A Commercial Lt-Gaas Emitter, Jose Isaac Santos Batista

Graduate Theses and Dissertations

This thesis presents computational models of terahertz (THz) photoconductive antenna (PCA) emitter using COMSOL Multiphysics commercial package. A comparison of the computer simulated radiated THz signal against that of an experimentally measured signal of commercial reference LT-GaAs emitter is presented. The two-dimensional model (2D) aimed at calculating the photoconductivity of a black phosphorus (BP) PCA at two laser wavelengths of 780 nm and 1560 nm. The 2D model was applied to the BP PCA emitter and the LT-GaAs devices to compare their simulated performance in terms of the photocurrent and radiated THz signal pulse. The results showed better performance of …

Design And Development Of Techniques To Ensure Integrity In Fog Computing Based Databases, Abdulwahab Fahad S. Alazeb

Graduate Theses and Dissertations

The advancement of information technology in coming years will bring significant changes to the way sensitive data is processed. But the volume of generated data is rapidly growing worldwide. Technologies such as cloud computing, fog computing, and the Internet of things (IoT) will offer business service providers and consumers opportunities to obtain effective and efficient services as well as enhance their experiences and services; increased availability and higher-quality services via real-time data processing augment the potential for technology to add value to everyday experiences. This improves human life quality and easiness. As promising as these technological innovations, they are prone …

Synthesis And Performance Testing Of Ecm Fiber Scaffolds, Cassandra Reed

Graduate Theses and Dissertations

The progression of regenerative medicine has advanced the treatment of multiple illnesses and injuries throughout the years. A good example of the benefits of this research is the work that has gone into volumetric muscle loss (VML), where more than 20% of the muscle is loss. Skeletal muscle makes up 40% of the human body so a loss of that size greatly diminishes the strength, the flexibility, physiology, and quality of life of the injured individual. For that reason, various techniques are used to counteract the loss of structure and innate cellular signaling in order to circumvent that from happening. …

Microfabrication And Electrochemical Characterization Of A Novel Su-8 Probe With An Array Of Individually Addressable Electrodes Suitable For Redox Cycling Experiments In Ultra-Small Volumes, Mahsa Lotfi Marchoubeh

Graduate Theses and Dissertations

Redox cycling is an electrochemical technique that utilizes closely spaced generator and collector electrodes to cycle reversible redox species between their oxidative states. With advantages in signal amplification, selectivity of species based on their electrochemical reaction mechanism, and limited or no background subtraction, this technique is well suited for selective detection of important electrochemically active molecules such as dopamine at basal or slowly changing levels.

Miniaturized medical devices have become an area of great interest for measurement of chemicals in limited volumes with low concentrations or in sensitive tissues. A probe on a polymeric SU-8 substrate with suitable dimensions and …

Tale Of The Tape: A Study Of Two-Year College Student-Athletes, Dustin Grover

Graduate Theses and Dissertations

Two-year athletic programs bring many unique elements to a college campus, many of which help to create a comprehensive student experience. Quantifying this experience is difficult as little data has been collected historically on two-year college athletes. The purpose of conducting this study was to create a profile of a rural two-year college student-athlete and to utilize the data to determine if participation in athletics had any effect on student success measures. This study will help college administrators build a better understanding of the two-year college student-athlete, aiding their decision-making regarding the prioritization of college athletics on their campuses. These …

Shallow 3d Shear Wave Velocity Model And Revised Site Period Prediction Map For The Mexico City Basin, Rendon Martin Rieth

Graduate Theses and Dissertations

The goal of this study was to revise the existing site period prediction map and to develop a shallow 3D shear wave velocity model of the Mexico City Basin. To accomplish this goal, an extensive literature review was performed to compile as much pertinent shear wave velocity and site period data for the region. In total, 75 sites were used to revise the site period prediction map and 40 sites were used to develop the shear wave velocity model. The 2004 Complementary Technical Standards of Mexico site period prediction map was adjusted with new site period measurements across the basin …

Weather Permitting, Acadia Kandora

Graduate Theses and Dissertations

Weather Permitting is an exhibition of objects and printed matter, primarily in the form of publicationsthat examine my relationship to nature and the idea of nature as both sanctuary and armor. At a young age, my parents would take my on a hike every Sunday instead of going to church. The hikes acted as a weekly pilgrimage deep into the woods and a ritual instilling the idea of nature being a place of spiritual refuge and retreat. A sanctuary - of course, weather permitting.

As I grew up and experienced hardship, my first instinct has always been to go hide …

Comparison Of The Resistance Of Belitic Calcium Sulfoaluminate Cement And Portland Cement To Sulfate Attack And Sulfuric Acid, Rilye Dillard

Graduate Theses and Dissertations

Microbially induced corrosion (MIC) is a fairly common concrete deterioration mechanism with many negative effects. MIC is a complex chemical and biological process that occurs in sewage systems and is nearly impossible to replicate in a laboratory setting. For this study, sulfate and sulfuric acid attack on concrete were studied to mimic two stages of the MIC process. The ASTM C1012, Standard Test Method for Length Change of Hydraulic-Cement Mortars Exposed to a Sulfate Solution and a modified ASTM C1012 accelerated method were used to compare the sulfate resistance of belitic calcium sulfoaluminate (BCSA) cement, portland cement (PC), and PC-fly …

An Investigation Of Testing Parameters On The Frictional Properties Of Patterned Core-Shell Nanostructures, Colin Phelan

Graduate Theses and Dissertations

Friction tests are a beneficial means to analyze the tribological characteristics and advantages of materials and textured surfaces. However, the selected test parameters can significantly influence the results. This work explores the significance of the friction testing parameters on the frictional performances of core-shell nanostructure-textured surfaces (CSNTSs). Several applied normal loads (10 μN, 100 μN, and 500 μN) and diamond counterface indenter tip radii (1 μm, 5 μm, and 20 μm) were selected for the testing of Al/diamond-like-carbon (DLC) and Al/amorphous silicon (a-Si) CSNTSs. The measured friction values of the CSNTSs were then compared to a matching Al/DLC film and …

Experimental Design And Preliminary Testing For Skewed Special Moment Frame Prequalification, Sara Alimirzaei

Graduate Theses and Dissertations

Special moment frames having specially detailed connections are common in high seismic regions, providing architectural flexibility for passageways and views without brace obstructions. In situations where the building framing layout requires deviation from typical rectangular framing, skew in the moment frame connections may be required. Currently, the AISC prequalified connections only include testing of orthogonal moment frame connections and it is unclear whether the existing design methods can accommodate skew at the beam-to- column connections. To investigate the effect of out-of-plane skew on the performance of reduced beam section special moment frame connections, an experimental test is designed and a …

Characterization, Incidence, And Epidemiology Of Two Novel Strawberry Rhabdoviruses, Ava Wait

Graduate Theses and Dissertations

Strawberry is the most important berry crop, grown in most temperate regions around the world. In the early 2000s and in 2012-2013, viral disease devastated strawberry production in California and Florida respectively; causing multimillion dollar losses. This occurred because viruses were moving in the field undetected. The modern strawberry (Fragaria x ananassa Duch.) is tolerant to single and double infections; yet when several viruses infect plants, symptoms as severe as plant death can occur. To prevent future epidemics, the use of virus-tested planting materials is essential. In 2019, rhabdovirus-like sequences were detected in strawberry using a combination of high-throughput sequencing …

Development Of An Ultraviolet Absorbance Assay To Estimate Air Entrainer Dosing For Concrete Containing Fly Ash, James Spencer

Graduate Theses and Dissertations

Fly ash is a coal combustion byproduct that can be used as a supplementary cementitious material (SCM) in concrete, offering benefits such as increased workability, durability, and strength. Fly ash can be used as a partial replacement to cement, reducing concrete productions costs and decreasing disposal in landfills. However, variability of fly ash properties (e.g., carbon content, adsorption site density) confounds estimates of the air entraining admixture (AEA) dose needed to achieve a specified air content in concrete. Air entrainment is needed to improve freeze-thaw resistance and limit concrete cracking. The foam index (FI) test is currently used to estimate …

Effects Of Heme Oxygenase 1 Inducer, T-Bhq On Growth Of Multiple Myeloma Cell Lines, And On Osteoblast And Osteoclast Differention, Alyaa Alansari

Graduate Theses and Dissertations

Expansion of plasma cells within the bone marrow constitutes the onset of multiple myeloma (MM). This disease manifests clinically primarily through the formation of osteolytic bone lesions that can lead to osteoporosis. The reason for the development of such lesions is the disruption of the equilibrium between bone resorption and bone formation as a result of proliferation of osteoclasts and reduction in the number of osteoblasts in the process of differentiation of mesenchymal stem cells (MSCs). The maintenance of bone architecture is critically dependent on osteoblasts and osteoclasts, the activity of which is underpinned by a range of soluble factors. …

Ancestral Pursuits: A Multicultural Celebration Of Identity & Race, Charlotte Cates Castro

Graduate Theses and Dissertations

Using critical historical rhetorical methods along with critical race and decolonial theory, this project situates ancestral pursuits as a communication-centered discursive formation by investigating the rhetorical strategies modern biotech and genealogy companies utilize to influence contemporary discourse around identity and belonging and narrate ethnicity and genealogy as acts of consumption. Through direct-to-consumer DNA testing and complimentary services, modern day biotech and genealogy companies like Ancestry and 23andMe market personalized insights into ancestry, genealogy, inherited traits, and health data that promise to connect users to their past, as well as to situate them in present-day society, through a deeper understanding of …

Economic And Ecosystem Impacts Of Gm Maize In South Africa, Kristiina Ala-Kokko

Graduate Theses and Dissertations

White maize in South Africa is the only staple crop produced on a widespread commercial basis for direct human consumption using genetically modified (GM) cultivars. Using a combined economic and environmental approach, we estimate the total welfare benefits attributable to GM white maize in South Africa for 2001-2018 are $694.7 million. Food security benefits attributable to GM white maize in South Africa also manifest through an average of 4.6 million additional white maize rations annually. To achieve these additional annual rations using conventional hybrid maize, the additional land required would range from 1,088 hectares in 2001 to 217,788 hectares in …

Pathogenicity Of Staphylococcus Agnetis Associated With Lame Broilers With Osteomyelitis, Sura Faris Salih Zaki

Graduate Theses and Dissertations

We developed High Resolution Melt Analysis (HERMA) as a rapid and reliable molecular diagnostic assay for the detection and identification of the main bacterial species recovered from the blood and lesions of bacterial chondronecrosis with osteomyelitis (BCO) from the lame broilers at the University of Arkansas poultry research farm. Also, the present study confirms that raising young birds on suspended wire flooring has been proved to successfully induce lameness attributable to BCO with birds being more susceptible to bacteraemia than those that were raised on litter flooring. The newly described pathogen, Staphylococcus agnetis, has been reported to be overrepresented in …

Understanding Gender Gaps In Student Achievement And Stem Majors: The Role Of Student Effort, Test Structure, Self-Perceived Ability, And Parental Occupation, Lina Anaya Beltran

Graduate Theses and Dissertations

Increasing women’s participation in Science, Technology, Engineering, and Mathematics (STEM) has become a policy goal for many countries. This dissertation focuses on the origin and measurement of gender gaps in student achievement and self-perceived ability, as well as their potential role in predicting college career choices in STEM.

The first two chapters provide an international overview of gender achievement gaps and focus on issues around measurement using data from the Programme for International Student Assessment (PISA). These chapters study the role of student effort in predicting gender gaps in achievement and whether or not test structure, defined as question difficulty …

Development Of Biomaterials For Drug Delivery, Raquel De Castro

Graduate Theses and Dissertations

Drug delivery systems (DDS) have highly evolved in the last decades with the development of hydrogels and nanoparticles. However, high systemic uptake, side effects, low bioavailability, and encapsulation efficiency continue to be a major hurdle faced by such DDSs.

Nanoparticles and hydrogels can be specifically designed for targeted DDSs to mitigate some of the problems. This dissertation aimed to design two DDSs for ocular drug delivery and one for cancer treatment. The first project sought to develop chitosan nanoparticles (Cs-NP) using PEGDA as a copolymer to encapsulate gentamicin (GtS) for ocular drug delivery. Cs-NPs contain positive charges that can interact …

Economic Feasibility Of Sub-Surfaced Poultry Litter, James Timothy Stults

Graduate Theses and Dissertations

Livestock producers routinely spread fertilizer or broadcast poultry litter to improve forage production. With poultry litter widely available across the Southeastern United States and a cheaper source of plant nutrition than fertilizer when proximal to application sites, the novel application of litter below the soil surface, while costly, allows for greater nutrient retention than broadcasting. Since quantifying costs and benefits of sub-surface litter application (SSLA) is complex, we develop and present a spreadsheet tool for automated comparison between SSLA, fertilizer, and broadcasted litter for user-specific scenarios involving equipment choices (new, used, custom), desired nutrient needs for crops grown, litter nutrient …

Biochemical Characterization Of Small Molecule Inhibitor Binding On A Ras Related Gtpase And Its Effector Interactions, Djamali Muhoza

Graduate Theses and Dissertations

The Ras superfamily of GTPases has 167 proteins that are involved in various cellular processes such as proliferation, transformation, migration, and inhibition of cell death. Mutations, abnormal expression, and function of these proteins are observed in many diseases, including several forms of cancer. Even though these GTPases were among the first discovered oncogenes, no successful Ras drug candidate has successfully passed clinical trials. Drugs targeting these proteins have failed mainly because of the complexity of their regulation, their high affinity to GTP, and their structure’s dynamic nature. Recently, novel promising targeting approaches have renewed interest in the Ras drug discovery …

Examining The Demographic And Situational Characteristics That Predict News-Media Coverage Of Bias Homicides:, Caitlin Tidwell

Graduate Theses and Dissertations

Recent trends indicate that incidents of hate crime have become increasingly more violent since 2017, resulting in an overall increase in incidents of bias homicide specifically. Knowledge of bias crime among the general public largely derives from news media sources and, unfortunately, research that illustrates how the media covers and/or portrays bias crime incidents remains underdeveloped. Using theories of strategic news making, the current study examines the types of bias homicide incidents that receive media coverage by constructing a unique database of newspaper articles from prominent, national papers for 216 bias homicides that occurred between 2000 and 2019 drawn from …

Study Of Static And Dynamical Properties Of Complex Antiferroelectrics Materials, Kinnary Yogeshbhai Patel

Graduate Theses and Dissertations

The aim of this dissertation is the investigation of the static and dynamical properties of the complex antiferroelectric materials using Effective Hamiltonian method and First principles calculations. In chapter 3, a novel elemental interatomic coupling in perovskite materials which bilinearly couples the antiferroelectric displacements of cations with the rotations of the oxygen octahedra. This new coupling explains a very complex crystal structure of prototypical antiferroelectric PbZrO3. My explanation provides a unified description of many other complex antipolar crystal structures in variety of perovskite materials, including the occurrence of incommensurate phases in some of them. In chapter 4, results and analysis …

Network-Based Detection And Prevention System Against Dns-Based Attacks, Yasir Faraj Mohammed

Graduate Theses and Dissertations

Individuals and organizations rely on the Internet as an essential environment for personal or business transactions. However, individuals and organizations have been primary targets for attacks that steal sensitive data. Adversaries can use different approaches to hide their activities inside the compromised network and communicate covertly between the malicious servers and the victims. The domain name system (DNS) protocol is one of these approaches that adversaries use to transfer stolen data outside the organization's network using various forms of DNS tunneling attacks. The main reason for targeting the DNS protocol is because DNS is available in almost every network, ignored, …

Memory And Rememory: Critically Cultivating An Appropriate Response Through A Storied Approach To Listening, Katie W. Powell

Graduate Theses and Dissertations

This dissertation argues for a storied approach to listening from the perspective of a white Southern woman. To do this, I carefully followed the work of two community groups. One, the Washington County Community Remembrance Project, is working to install a marker venerating Aaron, Anthony, and Randall, three enslaved people who were lynched in our area in 1856. The other, the James H. Berry United Daughters of the Confederacy, is responsible for installing a Confederate statue on the Bentonville Square in 1908 that was removed in 2020. As illustrated by the use of archival research and embedded participation in interracial …

Consumer Motivations And Perceived Value In Online Second-Hand Luxury Fashion Shopping, Murphy Brianne Aycock

Graduate Theses and Dissertations

The second-hand luxury fashion market is growing four times faster than the primary luxury fashion market and already represents a $24 billion market today (Beauloye, 2019; Siwak, 2020). Younger generations such as millennials and Gen Z are buying and selling preowned luxury products almost three times faster than any other age group (Beauloye, 2019). Digital selling platforms such as The RealReal and Vestiaire Collective are fueling the growth of the second-hand luxury fashion market (Beauloye, 2019). Despite the increased consumer interests and sales growth in the second-hand luxury fashion market, existing research has not concentrated on the underlying motivations of …

An 8-Bit Analog-To-Digital Converter For Battery Operated Wireless Sensor Nodes, Marvin Wayne Suggs Jr.

Graduate Theses and Dissertations

Wireless sensing networks (WSNs) collect analog information transduced into the form of a voltage or current. This data is typically converted into a digital representation of the value and transmitted wirelessly using various modulation techniques. As the available power and size is limited for wireless sensor nodes in many applications, a medium resolution Analog-to-Digital Converter (ADC) is proposed to convert a sensed voltage with moderate speeds to lower power consumption. Specifications also include a rail-to-rail input range and minimized errors associated with offset, gain, differential nonlinearity, and integral nonlinearity. To achieve these specifications, an 8-bit successive approximation register ADC is …

Analog Spiking Neural Network Implementing Spike Timing-Dependent Plasticity On 65 Nm Cmos, Luke Vincent

Graduate Theses and Dissertations

Machine learning is a rapidly accelerating tool and technology used for countless applications in the modern world. There are many digital algorithms to deploy a machine learning program, but the most advanced and well-known algorithm is the artificial neural network (ANN). While ANNs demonstrate impressive reinforcement learning behaviors, they require large power consumption to operate. Therefore, an analog spiking neural network (SNN) implementing spike timing-dependent plasticity is proposed, developed, and tested to demonstrate equivalent learning abilities with fractional power consumption compared to its digital adversary.

Artistry In Air: The Story Of The Younkins, Beth Lewis

Graduate Theses and Dissertations

For sixty years, a Northwest Arkansas family has dominated the world of general aviation by drawing upon its wealth of expertise, innovation and exceptional talent. Jim Younkin, an electrical engineer, invented an autopilot series that revolutionized the industry. His son, Bobby became one of the top aerobatic pilots in the world and Jim’s grandchildren, Matt and Amanda, also became critically acclaimed performers in the air show business. Like his father, Matt is ranked among the best of pilots in the industry. Jim also received national recognition for his stunning recreations of and restorations of historical aircraft. Bobby operated Younkin Airshows, …

Analysis Of Photodetector Based On Zinc Oxide And Cesium Lead Bromide Heterostructure With Interdigital Metallization, Tanveer Ahmed Siddique

Graduate Theses and Dissertations

In this thesis, photodetector based on the zinc oxide and cesium lead bromide hetero structure were fabricated and characterized. Zinc oxide (ZnO) nanoparticles were synthesized using solution processing and cesium lead bromide (CsPbBr3) thin film was synthesized using two step deposition method. Three phonon modes were obtained by the Raman spectroscopy of ZnO nanoparticles. X-ray diffraction spectra of ZnO exhibits five exciton peaks which denotes that the synthesized ZnO structure was of good crystallinity with wurtzite hexagonal phase. The absorbance spectrum of ZnO shows the bandgap (Eg) in the order of 3.5 eV that aligns with reported results. The photoluminescence …