Physical Sciences and Mathematics Commons^™

Assessing Commercial Organic And Conventionally Grown Vegetables By Monitoring Selected Heavy Metals Found In Them., Charles Kafui Dotse

Electronic Theses and Dissertations

Commercially available organic and conventionally grown vegetables were studied by quantitative determination of selected metals in them and to determine if any differences found are statistically significant. These findings can help the consumers to determine if the vegetable products are within the recommended maximum limits as proposed by the joint FAO/WHO Expert committee on organic foods designation. Eight edible vegetables were purchased from local stores in both the organic and conventionally grown categories. Samples were digested with concentrated nitric acid and the metals monitored were zinc, copper, lead, iron, cadmium, and nickel using flame atomic absorption. The concentration range for …

Response-Calibration Techniques For Antenna-Coupled Infrared Sensors, Peter Krenz

Electronic Theses and Dissertations

Infrared antennas are employed in sensing applications requiring specific spectral, polarization, and directional properties. Because of their inherently small dimensions, there is significant interaction, both thermal and electromagnetic, between the antenna, the antenna-coupled sensor, and the low-frequency readout structures necessary for signal extraction at the baseband modulation frequency. Validation of design models against measurements requires separation of these effects so that the response of the antenna-coupled sensor alone can be measured in a calibrated manner. Such validations will allow confident extension of design techniques to more complex infrared-antenna configurations. Two general techniques are explored to accomplish this goal. The extraneous …

Strong Orbit Equivalence And Residuality, Brett M. Werner

Electronic Theses and Dissertations

In this dissertation, we consider notions of equivalence between minimal Cantor systems, in particular strong orbit equivalence. By constructing the systems, we show that there exist two nonisomorphic substitution systems that are both Kakutani equivalent and strongly orbit equivalent. We go on to define a metric on a strong orbit equivalence class of minimal Cantor systems and prove several properties about the metric space. If the strong orbit equivalence class contains a finite rank system, we show that the set of finite rank systems is residual in the metric space. The last result shown is that set of systems with …

Using Transitivity With Nearest Neighbor To Reduce Error In Sample-Based Pearson Correlation Coefficients, Taylor Phillips

Electronic Theses and Dissertations

Pearson product-moment correlation coefficients are a well-practiced quantification of linear dependence seen across many fields. When calculating a sample-based correlation coefficient, the accuracy of the estimation is dependent on the quality and quantity of the sample. Like all statistical models, these correlation coefficients can suffer from overfitting, which results in the representation of random error instead of an underlying trend.

In this paper, we discuss how Pearson's product-moment correlation coefficients can utilize information outside of the two items for which the correlation is being computed. By introducing a relationship with one or more additional items that meet specified criterion, our …

Lifting Module Maps Between Different Noncommutative Domain Algebras, Jonathan Von Stroh

Electronic Theses and Dissertations

The classical Carathéodory interpolation problem is the following: let n be a natural number, a₀, a₁, . . . , a_N be complex numbers, and D the unit disk. When does there exist an analytic function F : D → C and complex numbers a_N+1, a_N+2, . . . such that F(z) = a₀ + a₁z + a₂z² + . . . + a_Nz^N + a_N+1z^N+1 + . . . and ||F||_∞ < 1? In 1967, Sarason used operator theory techniques to give an elegant solution to the Carathéodory interpolation problem. In 1968, Sz.-Nagy and Foias extended Sarason's approach into a commutant lifting theorem. Both the theorem and the technique of the proof have become standard tools in control theory. In particular, the commutant lifting theorem approach lends itself to a wide range of generalizations. This thesis concerns one such generalization.

Arias presented generalizations of the original …

Novel Photochemical Methodologies For Diversity Oriented Synthesis And Screening Of Combinatorial Libraries, Roman Askatovich Valiulin

Electronic Theses and Dissertations

The main goal of this project was to develop an efficient methodology allowing rapid access to structurally diverse scaffolds decorated with various functional groups.

Initially, we discovered and subsequently developed an experimentally straightforward, high-yielding photoinduced conversion of readily accessible diverse starting materials into polycyclic aldehydes and their (hemi)acetals decorated by various pendants. The two step sequence, involving the Diels-Alder addition of heterocyclic chalcones and other benzoyl ethylenes to a variety of dienes, followed by the Paternò-Büchi reaction, was described as an alkene-carbonyl oxametathesis. This methodology offers a rapid increase in molecular complexity and diversity of the target scaffolds.

To develop …

A Location Aware P2p Voice Communication Protocol For Networked Virtual Environments, Gabor Papp

Electronic Theses and Dissertations

Multiparty voice communication, where multiple people can communicate in a group, is an important component of networked virtual environments (NVEs), especially in many types of online games. While most research has been conducted on one-to-one communication, we focus on group communication. In this dissertation, we present the first measurement study on the characteristics of multiparty voice communications and develop a model of the talking and silence periods observed during multiparty communication. Over a total of 5 months, we measured over 11,000 sessions on an active multi-party voice communication server to quantify the characteristics of communication generated by game players, including …

Item Order Effects On Attitude Measures, Pei-Hua Chen

Electronic Theses and Dissertations

The purpose of this dissertation was to examine the effects of altered item order on attitude measures for both computerized adaptive and conventional survey formats. Based on items modified from a dissertation/thesis completion survey (Green & Kluever, 1997) with three scales, three survey versions were generated with items ordered by difficulty as hard-to-easy (H-E), easy-to-hard (E-H), and five medium trait level items presented first followed by randomly ordered items (M-R) for conventional survey format. Significant differences in item difficulty and item discrimination were found for two of the three scales. Differences in scale reliability were detected for the procrastination and …

Physicochemical And Thermochemical Properties Of Sulfonated Poly(Etheretherketone) Electrolyte Membranes, Stephen Rhoden

Electronic Theses and Dissertations

Fuel cells have long been seen as an alternative to combustion powered and diesel powered engines and turbines. Production of energy via a fuel cell conversion method can generate up to 60% efficiency in comparison to 30% using a combustion powered engine, with low co-production of harmful side-products. The polymer electrolyte membrane (PEM) adapted for the fuel cell application is one of the main components that determines the overall efficiency. This research project was focused towards novel PEMs, such as sulfonated poly(etheretherketone) or SPEEK, which are cost-efficient and robust with high proton conductivities under hydrated conditions. The degree of sulfonation …

The Influence Of Sexual Selection On Behavioral And Physiological Mechanisms Underlying Reproductive Success In Male Cape Ground Squirrels (Xerus Inauris), Mary Beth Manjerovic

Electronic Theses and Dissertations

Sexual selection is considered a powerful evolutionary force responsible for the enormous diversity found in reproductive morphology, physiology, and behavior. I addressed questions related to selection in the Cape ground squirrel (Xerus inauris), a species characterized as highly social and promiscuous. These attributes often are responsible for variance in male reproductive success and as such, sexual selection theory predicts increased opportunity for sexual selection. I confirm that the predominant mechanism underlying genital evolution and competition for paternity in X. inauris is sperm competition. I find evidence that investment in sperm competition is costly and may reflect immunocompetence. I quantify reproductive …

Measurement Of Thermoelectric Properties Of Amorphous Silicon Based Thin Films, Rubina Sultan

Electronic Theses and Dissertations

It is important to understand thermal transport behavior in materials for technological and fundamental physics applications. Many efforts have been made in the past for explaining thermal conduction in solids. It has been observed that thermal transport properties may change with reducing size of the sample, especially as sample size approaches the nanoscale regime. The deviation in these properties, mainly in thermal conductivity, may change the choice of the material for different applications such as thermoelectricity. Thermoelectric materials are a possible source of sustainable energy and can play an important role in the fight against the present energy crisis. Recently, …

Mechanistic Importance Of Redox Potentials And Conformational Flexibility In Electron-Transferring Flavoproteins, Michael Anthony Swanson

Electronic Theses and Dissertations

The mitochondrial matrix flavoproteins electron transfer flavoprotein (ETF) and electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) are responsible for linking fatty acid β-oxidation with the main mitochondrial respiratory chain. Electrons derived from flavoprotein dehydrogenases are transferred sequentially through ETF and ETF-QO to ubiquinone and then into the respiratory chain via complex III. In this study, the effects of changes in ETF-QO redox potentials on its activity and the conformational flexibility of ETF were investigated.

ETF-QO contains one [4Fe-4S]^2+,1+ and one flavin adenine dinucleotide (FAD). In the porcine protein, threonine 367 is hydrogen bonded to N1 and O2 of the flavin ring …

Fast-Response Liquid Crystal Displays, Meizi Jiao

Electronic Theses and Dissertations

After about five decades of extensive material research and device development, followed by massive investment in manufacturing technology, thin-film-transistor liquid-crystaldisplay (TFT-LCD) has finally become the dominant flat panel display technology. Nowadays, LCD performances, such as viewing angle, contrast ratio, and resolution, have reached acceptable levels. The remaining major technical challenges are response time, light efficiency, and sunlight readability. Fast response time is desired to reduce motion blur and to enable field sequential color displays using red (R), green (G), and blue (B) LEDs (light emitting diodes) without noticeable color breakup. Sequential RGB colors would eliminate the commonly used spatial color …

Statistical Analysis Of Visible Absorption Spectra And Mass Spectra Obtained From Dyed Textile Fibers, Katie Margaret White

Electronic Theses and Dissertations

The National Academy of Sciences recently published a report which calls for improvements to the field of forensic science. Their report criticized many forensic disciplines for failure to establish rigorously-tested methods of comparison, and encouraged more research in these areas to establish limitations and assess error rates. This study applies chemometric and statistical methods to current and developing analytical techniques in fiber analysis. In addition to analysis of commercially available dyed textile fibers, two pairs of dyes are selected based for custom fabric dyeing on the similarities of their absorbance spectra and dye molecular structures. Visible absorption spectra for all …

Particle Matter Measurements For Inspection/Maintenance Programs, Daniel Joseph Pope

Electronic Theses and Dissertations

Particle emissions from Heavy Duty Diesel Vehicles (HDDVs) are currently measured by opacity or dynamometer gravimetric analysis. The Electronic Tailpipe Particle Sensor (ETaPS) is an inexpensive measurement device purported to give real time response to particle mass and was proposed as a possible addition to Inspection/Maintenance (I/M) programs. There were three goals to this study. The first was to verify ETaPS response to particle mass of HDDV exhaust. Integrated ETaPS signal was plotted against filter weight from dynamometer gravimetric analysis and a correlation was found. The second goal was to find a correlation between ETaPS readings and the Remote Sensing …

Emergent Geographies In Green Energy, Sean Tierney

Electronic Theses and Dissertations

A consensus on climate change is spurring an energy transition, but the geography of this transition is uneven and this paper evaluates the energy landscape globally, in the United States and in Colorado. Developed countries have taken the lead in installations and of next generation energy technology ownership. Green electricity has still not achieved parity with fossil fuels, which puts their adoption in the hands of policy makers who are trying to spur innovation with minimal financial disruption. Yet the future of green electricity is in question due to weak and fragmented policy regimes, but also because of inadequate R&D …

Determining The Presence Of An Ignitable Liquid Residue In Fire Debris Samples Utilizing Target Factor Analysis, Kelly Mchugh

Electronic Theses and Dissertations

Current fire debris analysis procedure involves using the chromatographic patterns of total ion chromatograms, extracted ion chromatograms, and target compound analysis to identify an ignitable liquid according to the American Society for Testing and Materials (ASTM) E 1618 standard method. Classifying the ignitable liquid is accomplished by a visual comparison of chromatographic data obtained from any extracted ignitable liquid residue in the debris to the chromatograms of ignitable liquids in a database, i.e. by visual pattern recognition. Pattern recognition proves time consuming and introduces potential for human error. One particularly difficult aspect of fire debris analysis is recognizing an ignitable …

Controlled Assembly And Electronic Transport Studies Of Solution Processed Carbon Nanotube Devices, Paul Stokes

Electronic Theses and Dissertations

Developing techniques for the parallel fabrication of Complementary Metal Oxide Semiconductor (CMOS) compatible single walled carbon nanotube (SWNT) electronic devices is of great importance for nanoelectronic applications. In this thesis, solution processed SWNTs in combination with AC dielectrophoresis (DEP) were utilized to fabricate CMOS compatible SWNT field effect transistors (FETs) and single electron transistors (SETs) with high yield and their detailed electronic transport properties were studied. Solution processing of SWNTs is attractive not only for the high throughput and parallel manufacturing of SWNT devices but also due to the ease of processing at room temperature, and compatibility with various substrates. …

Black Writing Ink Analysis By Direct Infusion Electrospray Mass Spectroscopy, Christopher M. Moody

Electronic Theses and Dissertations

An optimized method of extraction, an instrumental analysis method and data analysis was proposed for black writing inks based on direct infusion electrospray-mass spectrometry (ESI-MS). The sampling and analysis method is both minimally destructive and able to assess differences in inks from a reference collection of thirty ballpoint, gel, and rollerball inks. The methanol extracts of ink on paper samples were analyzed with three direct infusion (ESI-MS) methods. Each method varied scan voltage negative and positive, ESI fragmentor applied voltage (+120V, +0V, and -120V), and mobile phase additive. Direct infusion ESI-MS analysis, followed by pair-wise comparisons of the observed ion …

The Development Of Scalable Pump Techniques For Gg Iag Fiber Lasers And Passive Athermalization Techniques For Solid State Laser, William Hageman

Electronic Theses and Dissertations

This dissertation consists of two parts: research pertaining to the development of scalable pump techniques for gain guided index-antiguided fiber lasers and research relating to the development of passive athermalization schemes for solid state lasers. The first section primarily details the development of a side pump scheme that allows for power scaling of gain-guided index anti-guided fibers. While these fibers have been demonstrated in past research, none have used a pump technology capable of pumping with the efficiencies, uniformity, and necessary length to allow for scaling of the fiber lasers to high output powers. The side pumped scheme developed in …

A Robust Wireless Mesh Access Environment For Mobile Video Users, Fei Xie

Electronic Theses and Dissertations

The rapid advances in networking technology have enabled large-scale deployments of online video streaming services in today's Internet. In particular, wireless Internet access technology has been one of the most transforming and empowering technologies in recent years. We have witnessed a dramatic increase in the number of mobile users who access online video services through wireless access networks, such as wireless mesh networks and 3G cellular networks. Unlike in wired environment, using a dedicated stream for each video service request is very expensive for wireless networks. This simple strategy also has limited scalability when popular content is demanded by a …

Long Cavity Quantum Dot Laser Diode And Monolithic Passively Mode-Locked Operation, K Shavitranuruk

Electronic Theses and Dissertations

Advantage of the single QD active layer is its potential for very low threshold current density, which in turn can produce low internal optical loss. The low threshold current density and low internal loss thus enable a significant increase in laser diode cavity length. Because of the importance of the threshold current density in heatsinking, future technology of broad-area monolithic laser diodes can be implemented. The dissertation describes the development and the unique characteristics of single QD active layer laser with long cavity. The data are presented on single layer QD laser diodes that reach threshold current densities values of …

Markerless Tracking Using Polar Correlation Of Camera Optical Flow, Prince Gupta

Electronic Theses and Dissertations

We present a novel, real-time, markerless vision-based tracking system, employing a rigid orthogonal configuration of two pairs of opposing cameras. Our system uses optical flow over sparse features to overcome the limitation of vision-based systems that require markers or a pre-loaded model of the physical environment. We show how opposing cameras enable cancellation of common components of optical flow leading to an efficient tracking algorithm that captures five degrees of freedom including direction of translation and angular velocity. Experiments comparing our device with an electromagnetic tracker show that its average tracking accuracy is 80% over 185 frames, and it is …

Fabrication Of Integrated Optofluidic Circuits In Chalcogenide Glass Using Femtosecond Laser Direct Writing, Troy P. Anderson

Electronic Theses and Dissertations

Femtosecond laser direct writing (FLDW) is a versatile process that uses focused femtosecond pulses to modify the physical structure of a material, which can result in a shift of optical properties such as the linear and nonlinear refractive index. If the photon energy of the femtosecond pulses lies below the material bandgap, nonlinear absorption rather than linear absorption becomes the dominant mechanism of energy transfer to the material. In this manner, a focused femtosecond pulse train can be used to fabricate functional features such as optical waveguides, diffractive optical elements, or micro-fluidic elements within the volume of a transparent medium. …

Nonlinear Absorption And Free Carrier Recombination In Direct Gap Semiconductors, Peter D. Olszak

Electronic Theses and Dissertations

Nonlinear absorption of Indium Antimonide (InSb) has been studied for many years, yet due to the complexity of absorption mechanisms and experimental difficulties in the infrared, this is still a subject of research. Although measurements have been made in the past, a consistent model that worked for both picosecond and nanosecond pulse widths had not been demonstrated. In this project, temperature dependent two-photon (2PA) and free carrier absorption (FCA) spectra of InSb are measured using femtosecond, picosecond, and nanosecond IR sources. The 2PA spectrum is measured at room temperature with femtosecond pulses, and the temperature dependence of 2PA and FCA …

United States Land Cover Land Use Change, Albedo And Radiative Forcing: Past And Potential Climate Implications, Christopher A. Barnes

Electronic Theses and Dissertations

Land Cover Land Use (LCLU) change affects Earth surface properties including albedo that impose a radiative forcing on the climate. Recent spatially explicit satellite derived contemporary LCLU, albedo, and projected LCLU data are used to study the impact of LCLU change from 1973 to 2000, and from 2000 to 2050, on albedo and surface radiative forcing for the conterminous United States. Four research hypotheses concerned with past and potential future climate implications of LCLU change are addressed. The research described in this dissertation makes an important contribution to advancing understanding of the role of LCLU change on the climate system, …

An Evaluation Of Duck And Ring-Necked Pheasant Nest Survival And Nest Density In Relation To Patch Size And Landscape Variables In Eastern South Dakota, Keith J. Fisk

Electronic Theses and Dissertations

Grassland ecosystems in South Dakota have experienced significant transformations over the last 100 years. Landscapes are currently dominated by large agricultural fields interspersed with small, isolated grassland patches. These isolated grassland patches are hypothesized to experience decreased nest survival rates for ring-necked pheasants (Phasianus colchicus) and dabbling duck species due to small size and high degrees of fragmentation. Several natural resource agencies currently conserve grasslands throughout eastern South Dakota, but wildlife managers seek more information on how the size and spatial arrangement of grasslands affect targeted conservation strategies. Therefore, the objectives of this study were to: (1) evaluate the relationship …

Approaches Towards The Synthesis Of Bradyoxetin, Vanildo Martins Lima Braga

Electronic Theses and Dissertations

Quorum sensing bacteria produce and release chemical signal molecules (like N-acyl homoserine lactones, AHL) that increase in concentration as a function of cell density. The responses cover a large spectrum of process such as the virulence in Staphylococcus aureus, competence for DNA-uptake in Bacillus subtilis and Streptococcus pneumoniae, sporulation in Bacillus subtilis, conjugal plasmid transfer in Enterococcus faecalis, and bacteriocin production in lactic acid bacteria. The collapse of (AHL) signaling system in bacteria represents an attractive therapeutic approach towards the development of new antibiotics. Recently, a new extracellular modulator was isolated from a symbiotic bacterium (Bradyrhizobium japonicum) that nodulates soybean. …

Impervious Surfaces Mapping Using High Resolution Satellite Imagery, Tahmina Shirmeen

Electronic Theses and Dissertations

In recent years, impervious surfaces have emerged not only as an indicator of the degree of urbanization, but also as an indicator of environmental quality. As impervious surface area increases, storm water runoff increases in velocity, quantity, temperature and pollution load. Any of these attributes can contribute to the degradation of natural hydrology and water quality. Various image processing techniques have been used to identify the impervious surfaces, however, most of the existing impervious surface mapping tools used moderate resolution imagery. In this project, the potential of standard image processing techniques to generate impervious surface data for change detection analysis …

Bicircular Matroids With Circuits Of At Most Two Sizes, Torina Deachune Lewis

Electronic Theses and Dissertations

Young in his paper titled, Matroid Designs in 1973, reports that Murty in his paper titled, Equicardinal Matroids and Finite Geometries in 1968, was the first to study matroids with all hyperplanes having the same size. Murty called such a matroid an ``Equicardinal Matroid''. Young renamed such a matroid a ``Matroid Design''. Further work on determining properties of these matroids was done by Edmonds, Murty, and Young in their papers published in 1972, 1973, and 1970 respectively. These authors were able to connect the problem of determining the matroid designs with specified parameters with results on balanced incomplete block designs. …