Physical Sciences and Mathematics Commons^™

Few-Cycle Pulses Amplification For Attosecond Science Applications Modeling And Experiments, Michael Hemmer

Electronic Theses and Dissertations

The emergence of mode-locked oscillators providing pulses with durations as short as a few electric-field cycles in the near infra-red has paved the way toward electric-field sensitive physics experiments. In addition, the control of the relative phase between the carrier and the pulse envelope, developed in the early 2000’s and rewarded by a Nobel price in 2005, now provides unprecedented control over the pulse behaviour. The amplification of such pulses to the millijoule level has been an on-going task in a few world-class laboratories and has triggered the dawn of attoscience, the science of events happening on an attosecond timescale. …

Design, Fabrication, And Testing Of High-Transparency Deep Ultra-Violet Contacts Using Surface Plasmon Coupling In Subwavelength Aluminum Meshes, Clarisse Mazuir

Electronic Theses and Dissertations

The present work aims at enhancing the external quantum efficiencies of ultra-violet (UV) sensitive photodetectors (PDs) and light emitting diodes (LEDs)for any light polarization. Deep UV solid state devices are made out of AlGaN or MgZnO and their performances suffer from the high resistivity of their p-doped regions. They require transparent p-contacts; yet the most commonly used transparent contacts have low transmission in the UV: indium tin oxide (ITO) and nickel-gold (Ni/Au 5/5 nms) transmit less than 50% and 30% respectively at 300 nm. Here we investigate the use of surface plasmons (SPs) to design transparent p-contacts for AlGaN devices …

An Approach To Improve The Failure Rate Model Of A Solid State Laser By Utalizing The Physics Of Failure Methodology, Omar L. Thompson

Electronic Theses and Dissertations

The ability to predict the failure rate of any military laser is very critical. In-field laser usage does not support the troubleshooting and repairing of a complex electro optical system. The only published laser failure rate model was last updated by the Department of Defense in 1975. Consequently, the failure rate predicted is inaccurate due to model deficiencies. This dissertation has developed a laser failure rate model for diode pumped lasers with improved failure rate prediction accuracy. The model has surpassed the capabilities of the Department of Defense model by the inclusion of key performance attributes that are currently not …

Identifying And Addressing Specific Student Difficulties In Advanced Thermal Physics, Trevor I. Smith

Electronic Theses and Dissertations

As part of an ongoing multi-university research study on student understanding of concepts in thermal physics at the upper division, I identified several student difficulties with topics related to heat engines (especially the Carnot cycle), as well as difficulties related to the Boltzmann factor. In an effort to address these difficulties, I developed two guided-inquiry worksheet activities (a.k.a. tutorials) for use in advanced undergraduate thermal physics courses. Both tutorials seek to improve student understanding of the utility and physical background of a particular mathematical expression. One tutorial focuses on a derivation of Carnot's theorem regarding the limit on thermodynamic efficiency, …

Covering Systems Of Polynomial Rings Over Finite Fields, Michael Wayne Azlin

Electronic Theses and Dissertations

In 1950 Paul Erdos observed that every integer belonged to a certain system of congruences with distinct moduli. He called such systems of congruences covering systems. Utilizing his covering system, he disproved a conjecture of de Polignac asking, “for every odd k, is there a prime of the form 2n + k?” Examples of covering systems of the integers are presented along with some brief history and a sketch of the disproof by Erd?s. Open conjectures concerning covering systems and best known results of attempts to prove these conjectures are given. Analogies are drawn between the integers and Fq[x], and …

Ion Transport, Viscoelastic, And Thermal Properties Of Several Poly(Ethylene Glycol) And Poly(Propylene Glycol) Based Polymer Electrolytes, Benjamin Jacob Yancey

Electronic Theses and Dissertations

This dissertation explores the relationship between ionic conductivity, viscosity, and thermal properties of several MePEG and MePPG based copolymer electrolytes. In particular two main copolymer modifications have been investigated namely copolymerization with "bulky groups" and cross polymerization of MePEG and MePPG monomers. The modifications were made to vary the fractional free volume of the MePEG polymers. All of the copolymers obeyed the Doolittle equation. For both the bulky copolymers and MePEG/MePPG copolymers, increases in the FFV corresponded to increases in the viscosity and decreases in FFV correspond to decreases in viscosity. The FFV and H+ conductivity for these copolymers were …

Calcite Cementation Of Sixty-Five-Year-Old Aragonite Sand Dredge Pile, Nathan M. Snyder

Electronic Theses and Dissertations

Dredging of the harbor at Stocking Island, Bahamas (23°31'45"N, 75°49'41"W) in 1942 produced four dredge piles of cross-bedded aragonite skeletal sand. The spoils piles are on the leeward (western) shore of the island, where they are subject to minimal wave energy. Collectively they are 350 x 50 m in plan view and 2 m high. The surface is very well cemented, which requires a hammer and chisel for sampling. Samples were collected from six sites at various locations of the dredge pile. Samples were analyzed for both chemical and physical properties using thin-section examination, X-ray diffraction, X-ray fluorescence, bulk density …

Independence Polynomials Of Molecular Graphs, Cameron Taylor Byrum

Electronic Theses and Dissertations

In the 1980's, it was noticed by molecular chemists that the stability and boiling point of certain molecules were related to the number of independent vertex sets in the molecular graphs of those chemicals. This led to the definition of the Merrifield-Simmons index of a graph G as the number of independent vertex sets in G. This parameter was extended by graph theorists, who counted independent sets of different sizes and defined the independence polynomial F_G(x) of a graph G to be \sum_k F_k(G)x^k where for each k, F_k(G) is the number of independent sets of k vertices. This thesis …

Asymptotics Of Carleman Polynomials For Level Curves Of The Inverse Of A Shifted Joukowsky Transformation, Michael Carr Northington

Electronic Theses and Dissertations

Let L be a level curve of the inverse of the shifted Joukowsky transformation w [special characters omitted] w − 1 + (w − 1) –1, that is, [special characters omitted]In this thesis we investigate the asymptotic properties of the sequence of polynomials that are orthonormal over the interior domain of L with respect to the area measure. We establish strong asymptotic formulas describing the behavior of these polynomials (as their degree increases) at every point of the complex plane.

Large Margin Random Forests On Mixed Type Data, Sheng Liu

Electronic Theses and Dissertations

Incorporating various sources of biological information is important for biological discovery. For example, genes have a multi-view representation. They can be represented by features such as sequence length and physical-chemical properties. They can also be represented by pairwise similarities, gene expression levels, and phylogenetics position. Hence, the types vary from numerical features to categorical features. An efficient way of learning from observations with a multi-view representation of mixed type of data is thus important. We propose a large margin random forests classification approach based on random forests proximity. Random forests accommodate mixed data types naturally. Large margin classifiers are obtained …

Bipartite Density Of Generalized Petersen Graphs, Lisa Jordan Ewell

Electronic Theses and Dissertations

The bipartite density b(G) of a graph G with m edges is the maximum ratio [special characters omitted] where m0 is the number of edges in a bipartitesubgraph of G. In this study we determine the bipartite density of several classes of Generalized Petersen Graphs. These graphs are denoted by P(n, k), where n ≥ 3 and 1 ≤ k < n with n ≠ 2k. The Generalized Petersen Graph P(n, k) has vertices [special characters omitted] and edges [special characters omitted] where subscript addition is modulo n. We define subgraphs P'(n, k) of P( n, k) by deleting the edge vn –1v0 and the edges w iwi+k for n – k ≤ i ≤ n – 1. For P'(n, k) and many classes of P(n, k), we determine the exact number of edges which must be removed from P( n, k) to reduce it to a bipartite subgraph. In many classes of Generalized Petersen Graphs the exact bipartite density is derived. For example: b(P(n, k)) = 1 for n even, k odd; b(P(n, k)) = 1 – [special characters omitted] for n and k odd and n > k²; b(P( n, k)) is asymptotically 1 – [special characters omitted] for n odd, k even.

Design And Synthesis Of Novel Agrofungicides Based On Naturally Occurring Pbdes, Robert Alexander Smith

Electronic Theses and Dissertations

Cyanobacterial symbionts of Indo Pacific marine sponges, e.g. Dysidea sp., produce hydroxylated (OH-) polybrominated diphenyl ethers (PDBEs) which likely function as chemical deterrents owing to their antifungal and antibacterial properties. Limiting the therapeutic potential and agricultural use of these antimicrobial natural products are the negative connotations associated with non hydroxylated anthropogenic PBDEs. Anthropogenic PBDEs are pervasive global pollutants used as flame retardant additives in many household goods, e.g. furniture, textiles, and electronics. These molecules have a propensity to bioaccumulate in living organisms, they easily traverse the trophic food chains, they are readily passed from mother to offspring, and many of …

A Gis Investigation Of Regional Geologic Controls On Mercury Deposits In The Southwest Region Of Arkansas, Lindsey Carol Langsdon

Electronic Theses and Dissertations

The mercury district of southwest Arkansas, located within Clark, Pike, and Howard counties, contains 77 mapped mercury deposits, primarily in the form of cinnabar, found within the sandstones and shales of the Stanley and Jackfork Formations. The geographic locations of the majority of the deposits tend to form an east-northeast alignment in map view. Utilization of Geographic Information Systems (GIS) tools provided insight to the regional controls on the spatial distribution of the mercury deposits by examining the proposed relationships between mercury deposits and regional faults or changes in lithology, both of which have been suggested (Clardy and Bush, 1976) …

Conjugate Additions And Transposition Of The Allylic Alcohols Of Enol Ethers Of 1, 2-Cyclohexanedione., Barnabas Otoo

Electronic Theses and Dissertations

A variety of protected enolic forms of 1, 2-cyclohexanedione was prepared as substrates for conjugate addition studies using organocopper reagents. The sequence involved the enol ether preparation via the enolate, alkylation with an organometalic reagent, and oxidative rearrangement with pyridinium chlorochromate followed by the conjugate addition reactions. Protection of 1, 2-cyclohexanedione was achieved by reacting with chloro tert-butyldimethyl silane and subjected to alkylation. Steric problems were encountered and so an alternative protective group the methoxymethyl acetal was prepared and studied. Alkylation of these derivatives was successful; however, the oxidation was problematic and although evidence for rearrangement was observed in one …

P300-Based Bci Performance Prediction Through Examination Of Paradigm Manipulations And Principal Components Analysis., Nicholas Edward Schwartz

Electronic Theses and Dissertations

Severe neuromuscular disorders can produce locked-in syndrome (LIS), a loss of nearly all voluntary muscle control. A brain-computer interface (BCI) using the P300 event-related potential provides communication that does not depend on neuromuscular activity and can be useful for those with LIS. Currently, there is no way of determining the effectiveness of P300-based BCIs without testing a person's performance multiple times. Additionally, P300 responses in BCI tasks may not resemble the typical P300 response. I sought to clarify the relationship between the P300 response and BCI task parameters and examine the possibility of a predictive relationship between traditional oddball tasks …

The Correlation Of The Concentration Of Selected Metals Determined In Water And Fish Samples From A Public Pond., Paula Kay Edwards

Electronic Theses and Dissertations

The concentrations of heavy metals (Cd, Cu, Fe, Ni, Pb, Zn) were measured in water, and fish samples caught from the pond at Fishery Park in Unicoi County, TN. The water samples were collected once a week for 8 weeks. The amounts of metals in the muscle tissues, gill, and liver of the two fish species were measured. This was to determine if any correlation exists between the metal contents in water and those in the fish samples. The concentration ranges for the heavy metals found in the water samples are as follows: Zn 0.04-0.13; Cu, 0.00-0.00; Pb, 0.00-0.59; Cd, …

The Sir Model When S(T) Is A Multi-Exponential Function., Teshome Mogessie Balkew

Electronic Theses and Dissertations

The SIR can be expressed either as a system of nonlinear ordinary differential equations or as a nonlinear Volterra integral equation. In general, neither of these can be solved in closed form. In this thesis, it is shown that if we assume S(t) is a finite multi-exponential, i.e. function of the form S(t) = a+ ∑ⁿ_k=1 r_ke^-σ_kt or a logistic function which is an infinite-multi-exponential, i.e. function of the form S(t) = c + a/b+e^wt, then …

The Removal Of Wood Components From Hardwood By Hot Water, Rory Jara

Electronic Theses and Dissertations

Hot-water extraction of hemicelluloses from wood is a promising technology in the integrated biorefmery concept. A particular case is where the pulp industry makes co-products such as ethanol and acetic acid besides pulp thereby maximizing the value of biomass. Similarly, the oriented strand board (OSB) industry appears to be suitable for this technical approach as it is composed of large centralized facilities. Many studies have been carried out on the kinetics and mechanism of hot-water extraction of lignocellulosics. However, most of these studies were performed in batch reactors which are not best suited to determine intrinsic kinetics of hemicellulose dissolution …

The Analysis Of Palaeobotanical Remains From Native American Sites In The Tennessee Region Of The Upper Cumberland Plateau., Chase W. Beck

Electronic Theses and Dissertations

Sediment samples were collected from 3 rock shelter sites and one natural pond on the Upper Cumberland Plateau. Samples were processed to quantitatively and qualitatively evaluate pollen and charcoal abundance as well as other palaeobotanicals. The analysis was to determine when prehistoric Native Americans began controlled burns to enhance resources acquisition. Samples were also analyzed for the presence of pollen to determine vegetation changes that may accompany the use of controlled burns and to determine the onset of horticulture. The Upper Cumberland Plateau is often considered a marginal area used only seasonally by Native Americans; however, management practices may have …

Cyanoscorpionates And Transition Metal Complexes., Donald Martin Johnson

Electronic Theses and Dissertations

The new dihydrobis(4-cyano-3-tert-butylpyrazolylborate) ligand has been synthesized. Isolated crystals of the thallium complex were collected and structurally characterized by X-ray diffraction. Transition metal complexes of the ligand are currently under investigation.

Non-Classical Symmetry Solutions To The Fitzhugh Nagumo Equation., Arash Mehraban

Electronic Theses and Dissertations

In Reaction-Diffusion systems, some parameters can influence the behavior of other parameters in that system. Thus reaction diffusion equations are often used to model the behavior of biological phenomena. The Fitzhugh Nagumo partial differential equation is a reaction diffusion equation that arises both in population genetics and in modeling the transmission of action potentials in the nervous system. In this paper we are interested in finding solutions to this equation. Using Lie groups in particular, we would like to find symmetries of the Fitzhugh Nagumo equation that reduce this non-linear PDE to an Ordinary Differential Equation. In order to accomplish …

Early Stopping Of A Neural Network Via The Receiver Operating Curve., Daoping Yu

Electronic Theses and Dissertations

This thesis presents the area under the ROC (Receiver Operating Characteristics) curve, or abbreviated AUC, as an alternate measure for evaluating the predictive performance of ANNs (Artificial Neural Networks) classifiers. Conventionally, neural networks are trained to have total error converge to zero which may give rise to over-fitting problems. To ensure that they do not over fit the training data and then fail to generalize well in new data, it appears effective to stop training as early as possible once getting AUC sufficiently large via integrating ROC/AUC analysis into the training process. In order to reduce learning costs involving the …

A Study Of Improving The Parallel Performance Of Vasp., Matthew Brandon Baker

Electronic Theses and Dissertations

This thesis involves a case study in the use of parallelism to improve the performance of an application for computational research on molecules. The application, VASP, was migrated from a machine with 4 nodes and 16 single-threaded processors to a machine with 60 nodes and 120 dual-threaded processors. When initially migrated, VASP's performance deteriorated after about 17 processing elements (PEs), due to network contention. Subsequent modifications that restrict communication amongst VASP processes, together with additional support for threading, allowed VASP to scale up to 112 PEs, the maximum number that was tested. Other performance-enhancing optimizations that were attempted included replacing …

Spousal Concordance In Academic Achievements And Intelligence And Family-Based Association Studies Identified Novel Loci Associated With Intelligence., Yue Pan

Electronic Theses and Dissertations

Assortative Mating, the tendency for mate selection to occur on the basis of similar traits, plays an essential role in understanding the genetic variation on academic achievements and intelligence (IQ). It is an important mechanism explaining spousal concordance. We used principal component analysis (PCA) for spousal correlation. There is a significant positive correlation between spouses by the new variable PC1 (correlation coefficient=0.515, p<0.0001). We further research the genetic factor that affects IQ by using the same data. We performed a low density genome-wide association (GWA) analysis with a family-based association test to identify genetic variants that associated with intelligence as measured by WAIS full-score IQ (FSIQ). NTM at 11q25 (rs411280, p=0.000764) and NR3C2 at 4q31.23 (rs3846329, p=0.000675) were 2 novel genes that haven't been associated with IQ from other studies. This study may serve as a resource for replication in other populations and a foundation for future investigations.

A Comparative Study Between The Standards Of Learning And In-Class Grades., Randetta Lynn Fuller

Electronic Theses and Dissertations

We examined the Standards of Learning mathematics scores and in-class grades for a rural Virginia county public school system. We looked at third, fourth, fifth, sixth, and seventh grades as well as Algebra I, Algebra II, and Geometry classes. The purpose of this was to determine whether or not there is a strong correlation between the Standards of Learning and the students' in-class grades. Had a strong enough correlation between the Standards of Learning and in-class grades been found we would have used only the in-class grades to predict the Standard of Learning test scores. However, we found that the …

Analysis Of Optical Spikes Reveals Dynamics Of Aggregates In The Twilight Zone, Nathan Briggs

Electronic Theses and Dissertations

The "biological pump," whereby phytoplankton grow in the surface ocean, aggregate, and sink, is a critical process contributing to global atmospheric CO2 drawdown and provides the vast majority of food for deep ocean and benthic ecosystems. The strength of this pump hinges on the amount of material that stick together to form larger aggregates, the sinking rates of these aggregates, and the rate at which they are consumed as they sink. However, marine aggregates, also called "marine snow," are often fragile and notoriously difficult to sample, their sinking rates are highly variable and difficult to quantify, and their concentrations can …

Toward Using Games To Teach Fundamental Computer Science Concepts, Jeffrey Michael Edgington

Electronic Theses and Dissertations

Video and computer games have become an important area of study in the field of education. Games have been designed to teach mathematics, physics, raise social awareness, teach history and geography, and train soldiers in the military. Recent work has created computer games for teaching computer programming and understanding basic algorithms.

We present an investigation where computer games are used to teach two fundamental computer science concepts: boolean expressions and recursion. The games are intended to teach the concepts and not how to implement them in a programming language.

For this investigation, two computer games were created. One is designed …

Composing Music In Constrained Search Environments, Jeffrey Keene

Electronic Theses and Dissertations

Composing music with computers in constrained search environments adds complexities and problems not present in the traditional problem domain of generative music. The traditional and well researched mechanisms of Markov chains, genetic algorithms and data driven rule based systems do not directly map to a problem domain in which pitch choice and rhythm choice are likely to be highly limited.

We therefore explore several possible solutions to generating rhythms in extremely constrained environments with the goal of generating music that adheres to user specified constraints and is aesthetically pleasing.

Theoretical Properties And Estimation In Weighted Weibull And Related Distributions, Ryan Roman

Electronic Theses and Dissertations

The Weibull distribution is a well known and common distribution. In this thesis, theoretical properties of weighted Weibull distributions are presented. Properties of the non-weighted Weibull distribution are also reiterated for comparison. The probability density functions, cumulative distribution functions, survival functions, hazard functions and reverse hazard functions are given for each distribution. In addition, Glaser's Lemma is applied to determine the behavior of the hazard functions. The standardized moments, differential entropy, Fisher information and results based on the likelihood function are given for each distribution as well. These results are also shown for the Rayleigh distribution, a special case of …

Greening The Green Revolution: Moving Beyond Chemicals To Sustainable Agricultural Practices, Elizabeth G. Crawley

Electronic Theses and Dissertations

Agriculture has dominated the economy of many developing countries for centuries, which has led to development policies that center on agricultural development. An obvious approach to improved production is to decrease agricultural losses in the fields and increase efficiency to markets. This study focuses on the developmental role of pesticides and chemical fertilizers on non-traditional agricultural export farming and the adoption of IPM techniques. With farmers in the Comayagua Valley of Honduras, an Asian vegetable production center for the country, as the study population, the costs and benefits of planting oriental vegetables was examined. Statistical analysis was used to examine …