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Emergence Phenology And Nematode Associates Of The Woodwasp, Sirex Nigricornis F. (Hymenoptera: Siricidae), In Arkansas And Mississippi Forests, Jessica Ann Hartshorn

Graduate Theses and Dissertations

Sirex nigricornis F. (Hymenoptera: Siricidae) is a native woodwasp in eastern North America that inhabits dead and dying pine trees during its univoltine development. Sirex noctilio is native to Eurasia and North Africa and was discovered in the northeastern United States in 2004 after a century of accidental introductions across the Southern Hemisphere. Since then, it has spread to seven states and southern Ontario. There is concern about its potential to negatively affect the multi-billion dollar pine timber industry of the southeastern United States. Effective monitoring tools are necessary to track the spread and establishment of S. noctilio. Deladenus siricidicola …

Investigating Mineral Stability Under Venus Conditions: A Focus On The Venus Radar Anomalies, Erika Kohler

Graduate Theses and Dissertations

Radar studies of the surface of Venus have identified regions with high radar reflectivity concentrated in the Venusian highlands: between 2.5 and 4.75 km above a planetary radius of 6051 km, though it varies with latitude. Previous research has proposed several theories on the source of these anomalies, including increased surface roughness, metallic materials with higher dielectric constants, or ferroelectric materials. Prior work suggests several processes that could be the origin of these anomalies, such as surface-atmospheric interactions or low lying clouds or fog. Alternatively, these anomalies could result from a semi-metallic compound trapped at the cooler conditions in the …

Future Flowers, Eszter Takacs

Graduate Theses and Dissertations

This is a book-length poem presented in three untitled parts.

Phase-Field Models For Simulating Physical Vapor Deposition And Microstructure Evolution Of Thin Films, James Stewart Jr.

Graduate Theses and Dissertations

The focus of this research is to develop, implement, and utilize phase-field models to study microstructure evolution in thin films during physical vapor deposition (PVD). There are four main goals to this dissertation. First, a phase-field model is developed to simulate PVD of a single-phase polycrystalline material by coupling previous modeling efforts on deposition of single-phase materials and grain evolution in polycrystalline materials. Second, a phase-field model is developed to simulate PVD of a polymorphic material by coupling previous modeling efforts on PVD of a single-phase material, evolution in multiphase materials, and phase nucleation. Third, a novel free energy functional …

Guatemalan Exiles, Caribbean Basin Dictators, Operation Pbfortune, And The Transnational Counter-Revolution Against The Guatemalan Revolution, 1944-1952, Aaron Coy Moulton

Graduate Theses and Dissertations

When U.S. officials in 1952 approved the first Central Intelligence Agency (CIA) operation to overthrow Guatemalan president Jacobo Arbenz, they unknowingly stepped into a regional conflict that, for nearly ten years, included dissident Guatemalan exiles, Caribbean Basin dictators, and the Guatemalan governments of Arbenz and his predecessor Juan José Arévalo. Since the mid-1940s, exiles and dictators had denounced the Guatemalan Revolution as the product of Mexican, Soviet, and international communism. The anti-communist ideology of Guatemalan exiles, Nicaraguan dictator Anastasio Somoza, Honduran dictator Tiburcio Carías, and Dominican dictator Rafael Trujillo facilitated various conspiracies aimed to destabilize Arévalo and Arbenz’s governments throughout …

Experimental And Computational Studies Of Cortical Neural Network Properties Through Signal Processing, Wesley Patrick Clawson

Graduate Theses and Dissertations

Previous studies, both theoretical and experimental, of network level dynamics in the cerebral cortex show evidence for a statistical phenomenon called criticality; a phenomenon originally studied in the context of phase transitions in physical systems and that is associated with favorable information processing in the context of the brain. The focus of this thesis is to expand upon past results with new experimentation and modeling to show a relationship between criticality and the ability to detect and discriminate sensory input. A line of theoretical work predicts maximal sensory discrimination as a functional benefit of criticality, which can then be characterized …

Essays In Physicians Preference Items And Inventory Management Within The Healthcare Supply Chain, Mohammad A. Shbool

Graduate Theses and Dissertations

This work is composed of a number of topics in the healthcare area, which are approached separately with appropriate methodologies. The two topics deal with physician preference items via two different approaches. The first one investigates stock keeping unit (SKU) proliferation in healthcare organizations due to physician preference items (PPI). It captures perspectives of physicians and supply chain professionals about this problem through two surveys. The second topic builds a decision-making framework for the PPI selection process that can be used by healthcare organizations to make more objective decisions. A Multi-criteria decision making technique is implemented to illustrate the framework.

The Effects Of Dynamic Graphing Utilities On Student Attitudes And Conceptual Understanding In College Algebra, Ryan Vail Thomas

Graduate Theses and Dissertations

The goal of this study is to explore and characterize the effects of using a dynamic graphing utility (DGU) on conceptual understanding and attitudes toward mathematics, measured by the responses of college algebra students to an attitude survey and concepts assessment. Two sections of college algebra taught by the primary researcher are included in the study, with one group using the dynamic graphing utility Desmos (www.desmos.com), and the other using the TI-84 (or equivalent) graphing calculator as a control. The Precalculus Concept Assessment (Carlson, Oehrtman, & Engelke, 2010) was used to measure aspects of students’ conceptual understanding of course material, …

Design Of A Nutrient Reclamation System For The Cultivation Of Microalgae For Biofuel Production And Other Industrial Applications, Heather Sandefur

Graduate Theses and Dissertations

Microalgal biomass has been identified as a promising feedstock for a number of industrial applications, including the synthesis of new pharmaceutical and biofuel products. However, there are several economic limitations associated with the scale up of existing algal production processes. Critical economic studies of algae-based industrial processes highlight the high cost of supplying essential nutrients to microalgae cultures. With microalgae cells having relatively high nitrogen contents (4 to 8%), the N fertilizer cost in industrial-scale production is significant. In addition, the disposal of the large volumes of cell residuals that are generated during product extraction stages can pose other economic …

Development Of Electrochemical Sensors Suitable For In Vivo Detection For Neurotransmitters, Mengjia Hu

Graduate Theses and Dissertations

The electrochemical method of redox cycling was exploited to achieve new discoveries in neurotransmitter detection and to advance its suitability toward in vivo use. Redox cycling has advantages in signal amplification, selectivity of species based on their electrochemical reaction mechanisms, and limited or no background subtraction. Distinction of dopamine from norepinephrine in a mixture with an electrochemical method at unmodified electrodes was demonstrated for the first time in vitro. This ability resulted from a series of fundamental studies of redox cycling behavior of the catecholamines (dopamine, norepinephrine and epinephrine) using different electrode configurations. Taking advantage of the ECC’ mechanism associated …

Geospatial Analysis Of Droughts, Rice And Wheat Production, And Agrarian Vulnerability: A District-Level Study Of The Self-Calibrated Palmer Drought Severity Index In India, Aaron Michael Shew

Graduate Theses and Dissertations

Droughts have affected more people than any other natural disaster in the last century, causing billions in economic damages and millions of deaths. As the Sea Surface Temperatures (SST) have heated in the Indian Ocean, drought patterns across South Asia have changed; the Indian monsoon has become more volatile and less predictable. In this study, monthly self-calibrated Palmer Drought Severity Index (sc-PDSI) data for the time period between 1950 and 2009 were interpolated to India’s districts; then the data were analyzed for changes in frequency and severity. The data were further evaluated using Anselin’s Local Moran’s I Statistic to elicit …

Hardware Trojan Detection Via Golden Reference Library Matching, Lucas Weaver

Graduate Theses and Dissertations

Due to the proliferation of hardware Trojans in third party Intellectual Property (IP) designs, the issue of hardware security has risen to the forefront of computer engineering. Because of the miniscule size yet devastating effects of hardware Trojans, few detection methods have been presented that adequately address this problem facing the hardware industry. One such method with the ability to detect hardware Trojans is Structural Checking. This methodology analyzes a soft IP at the register-transfer level to discover malicious inclusions. An extension of this methodology is presented that expands the list of signal functionalities, termed assets, in addition to introducing …

Topics In The Detection Of Gravitational Waves From Compact Binary Inspirals, Shasvath Jagat Kapadia

Graduate Theses and Dissertations

Orbiting compact binaries - such as binary black holes, binary neutron stars and neutron star-black hole binaries - are among the most promising sources of gravitational waves observable by ground-based interferometric detectors. Despite numerous sophisticated engineering techniques, the gravitational wave signals will be buried deep within noise generated by various instrumental and environmental processes, and need to be extracted via a signal processing technique referred to as matched filtering.

Matched filtering requires large banks of signal templates that are faithful representations of the true gravitational waveforms produced by astrophysical binaries. The accurate and efficient production of templates is thus crucial …

A Geochemical Analysis Of The Arkansas Novaculite And Comparison To The Siliceous Deposits Of The Boone Formation, John Byron Scott Philbrick

Graduate Theses and Dissertations

Geochemical analyses of the Arkansas Novaculite, located within core structures of the Ouachita Mountains in west-central Arkansas, and penecontemporaneous chert of the lower Boone Formation, located atop the Springfield Plateau of southwest Missouri, northwest Arkansas, and northeast Oklahoma, have identified a significant concentration of both aluminum and potassium. This would seem to eliminate a biogenic origin and favor a volcanic source of the silica that comprises these units. Trace and rare earth element (REE) analysis also suggests that the Arkansas Novaculite and the chert in the lower Boone Formation may have both been formed from the same volcanic source.

The …

Design, Fabrication, And Testing Of A 3d Printer Based Microfluidic System, Carlton A. Mcmullen

Graduate Theses and Dissertations

A pneumatically actuated PDMS based microfluidic devices were designed and fabricated by soft-lithography. Two types of molds were fabricated out of different material for this experiment. The first mold, (device 1), was fabricated from a sheet of Polymethyl methacrylate (PMMA) material, similar to Plexiglas. The device features were micro-engraved onto the face of the material. The second mold, (device 2), was fabricated from the use of fused deposition modeling (FDM) 3D printing. The pumping efficiency of the PDMS devices was analyzed through the characterization of the micro-pumps flowrate with respect to the pumps driving pressure and the actuation frequency. Tested …

The Effects Of Meloidogyne Incognita And Heterodera Glycines On The Yield And Quality Of Edamame In Arkansas, Juliet Fultz

Graduate Theses and Dissertations

Edamame (Glycine max), also known as vegetable soybean, was introduced to the United States from Japan in 1890 and has been growing in popularity as a nutrient-rich, low-sugar snack in recent years. In 2012, the American Vegetable Soybean and Edamame, Inc. established the first domestic commercial processing plant in Mulberry, Arkansas and contracted local growers for production. Since the crop is harvested when seed are immature, management practices are different from those for traditional soybean. Plant-parasitic nematodes, particularly Meloidogyne incognita (southern root-knot) and Heterodera glycines (soybean cyst), are common in Arkansas and are pests of concern for edamame growers. Edamame …

Development Of Pre-Stressed Cfrp Fatigue Retrofits For Common Steel Bridge Connections, Korey Albert Pough

Graduate Theses and Dissertations

Aging or deterioration of the nation’s bridge infrastructure is a significant issue that requires attention. Causes for much of this deterioration can be attributed to two main factors, 1) corrosion, and 2) metallic fatigue, both of which work together to reduce the strength and serviceability of bridge components over time. In many instances, strengthening of bridge components using localized retrofits offers an economical and fast solution for increasing the longevity of existing steel bridges; however, such retrofits must be resilient to further corrosion and fatigue damage. In this study, a localized retrofit is developed using pre-stressed Carbon Fiber Reinforced Polymer …

Investigation Of A Numerical Algorithm For A Discretized Rubber-Belt Continuously Variable Transmission Dynamic Model And Techniques For The Measurement Of Belt Material Properties., Brian Gene Ballew

Graduate Theses and Dissertations

A numerical algorithm for modeling the dynamic response of a rubber-belt Continuously Variable Transmission (CVT) belt is recreated. The numerical attributes applied to the algorithm and difficulties with numerical stability are discussed in detail. The degrees of freedom of the system have been expanded to include the dynamics of the engine torque output and vehicle loads such as rolling resistance and aerodynamic drag. This was done to emphasize the use of the model as an analysis tool for simulating CVT/engine/vehicle response. The increased degrees of freedom require the addition of a linear dampening element between belt nodes to dampen resonance …

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 …

Investigations Into The Cross-Infectivity Of Nematode Parasites Of Cattle And Sheep, Eva Marie Wray

Graduate Theses and Dissertations

The existence of anthelmintic resistance is not singular in parasite species, host species or geographic region. It has become a problem of worldly stature, especially when considering sheep nematodes. Recommendations have been modified from chemical-based control to multipart, managerial intervention. Compared with nematodes of cattle, the worldwide resistance of sheep nematodes to anthelmintic remedies is much more pronounced and urgent. As the resistance to essentially all anthelmintic classes approaches a cautionary level, the implementation of non-chemical controls has grown increasingly essential. Six-6 to 8 month old Holstein steer calves, six-5 month old Katahdin ram lambs and eight-5 month old Suffolk …

An Exploration Of Performance-Based Funding At Four-Year Public Colleges In The North Central Association Of Colleges And Schools, Samuel Fincher

Graduate Theses and Dissertations

Performance-based funding has been used to help alleviate state and public calls for higher education accountability and more states have adopted this type of funding model (Tandberg & Hillman, 2014; Dougherty, Natow, & Vega, 2012). The purpose of this study was to explore performance-based funding and examine the relationship between types of funding and performance indicators in the North Central Association of Colleges and Schools (NCA). The state funding trends were examined for all of the states in the NCA. The correlations for state funding and four performance outcomes for all four-year higher education institutions were compared for three states …

High Temperature Silicon Carbide Mixed-Signal Circuits For Integrated Control And Data Acquisition, Ashfaqur Rahman

Graduate Theses and Dissertations

Wide bandgap semiconductor materials such as gallium nitride (GaN) and silicon carbide have grown in popularity as a substrate for power devices for high temperature and high voltage applications over the last two decades. Recent research has been focused on the design of integrated circuits for protection and control in these wide bandgap materials. The ICs developed in SiC and GaN can not only complement the power devices in high voltage and high frequency applications, but can also be used for standalone high temperature control and data acquisition circuitry.

This dissertation work aims to explore the possibilities in high temperature …

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 …

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. …

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 …

Model Development And Validation For Wind Generation Transmission Systems, Mahmood Shihadeh Saadeh

Graduate Theses and Dissertations

In this research a new benchmark system is proposed for wind energy transmission systems. New model development, validation, and calibration methods for power transmission systems are proposed and implemented as well. First, a model reduction criteria is chosen based on electrical interconnection and geographical information. Model development is then done using reduction techniques on an operation model provided by a transmission operator based on the chosen criteria. Then model validation is performed using actual PMU synchrophasor measurements provided by a utility company. The model development and validation process ensures the accuracy of the developed model and makes for a realistic …

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 …

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 …

Rupture In Abdominal Aortic Aneurysm, Qusay Alfaori

Graduate Theses and Dissertations

Quantification of abdominal aortic aneurysm development, its growth kinetics, and rupture criteria are important to decrease the risk of this life-threatening event. Uniaxial testing of healthy and collagen degraded aortic specimens from pigs was performed. A mathematical model, from the literature, for the stress-strain relationship that is suitable for describing the behavior of abdominal aortic tissue was used to derive specific tissue properties/parameters as a function of strain rate and as a function of specimen orientation. Analyses consisting of Finite Element Modeling of healthy and collagen degraded abdominal aortas were performed using ABAQUS finite element code and the measured properties. …

Examining Teachers' Perceptions And Adaptations Related To The First-Year Of Implementation Of The Common Core State Standards In A Rural Elementary School In Central Illinois, Jason Vicich

Graduate Theses and Dissertations

This study examined the latest mandated government policy of the Common Core State Standards (CCSS) and the Partnership for Assessment of Readiness for College and Careers (PARCC), which fully took effect during the 2014-2015 school year. The study sought to look at these changes through the eyes of a group of elementary teachers in rural Illinois as they work with and through these policy mandates during their initial year of implementation.

The study was conducted over the course of the 2014-2015 school year. Data was gathered through a three interview sequence, site visits and the administration of the SOCQ 75 …