Digital Commons Network^™

Adaptive Intensity Modulated Radiation Therapy Planning Optimization With Changing Tumor Geometry And Biology Enforcing Both Cumulative And Fraction Size Dose Constraints, Behlul Saka

Graduate Theses and Dissertations

Intensity Modulated Radiation Therapy (IMRT) is a modern technique of delivering radiation treatments to cancer patients. In IMRT technology, intensities must be chosen for the many small unit grids into which the beams are divided to produce a desired distribution of dose at points throughout the body with the goal of maximizing dose delivered to the tumor while sparing healthy tissues from excessive radiation and keeping dose homogeneous across the tumor. Although IMRT plans are optimized as a single overall treatment plan, they are delivered over 30-50 treatment sessions (fractions) and both cumulative and per-fraction dose constraints apply. The extended …

Integrated Planning For Rural Rail Transportation, Jeffrey Cohan Gwaltney

Graduate Theses and Dissertations

Population growth in rural areas has led to new interest in rail transportation. Planning a passenger rail system involves numerous difficult decisions, most representing a trade-off between customer service and cost. In this work, we attempt to integrate many of these planning decisions. We consider strategic decisions such as station location and vehicle procurement, as well as tactical issues that include vehicle scheduling. Our integrated model exploits the linear network structure that best suits many rural American communities, including Northwest Arkansas. Due to the intractability of the integrated rail planning problem, we have developed a customized heuristic approach to solve …

Inventory Models For Intermittent Highly Variable Demand And Policy Parameter Adjustments To Meet Desired Service Level Requirements, Yasin Unlu

Graduate Theses and Dissertations

This dissertation consists of three assays. The first assay examines the robustness of lead time demand models for the continuous review (r;Q) inventory policy. A number of classic distributions as well as distribution selection rules are examined under a wide variety of demand conditions. First, the models are compared to each other by assuming a known demand process and evaluating the errors associated with using a different model. Then, the models are examined using a large sample of simulated demand conditions. Approximation results of inventory performance measures - ready, rate excepted number of backorders and on-hand inventory levels are reported. …

Design And Implementation Of Metamaterial Based Strain Sensor Using Aperture Coupled Antenna, Michael Brandon Buscher

Graduate Theses and Dissertations

Strain sensors are used to convert the physical measured quantity of strain into an electrical signal suitable for processing by electronic equipment. Traditional strain sensors are comprised of a thin flexible film with a resistive pattern traced on the surface. As the sensor is deformed, the electrical resistance changes proportionally, giving a direct measure of the strain incurred. Metamaterials, particularly split ring resonators (SRR), lend themselves as a valuable tool for sensing applications due to their highly resonant nature and their very narrow bandwidth (high Q-factor). Due to very high field localization effects, they are extremely sensitive to both the …

Field-Based Constraints On The Origin Of The Benton Uplift, Ouachita Mountains, Rachel Victoria Keng

Graduate Theses and Dissertations

The Ouachita Mountains are an east-west trending fold-and-thrust belt exposed in west central Arkansas and southeastern Oklahoma. The Mississippian-Pennsylvanian Ouachita orogeny occurred when the Sabine arc terrane collided during south-facing subduction, during closure of the Cambrian passive margin of the North American plate. Deep-water Paleozoic strata were incorporated into an accretionary wedge as the Sabine terrane approached the North American plate. Folds and thrust faults in the Ouachita Mountains generally verge north due to tectonic transport of an accretionary wedge from south to north. Structures in the Benton and Broken Bow Uplifts (located in the core of the wedge) locally …

Visualizing The Spatial Localization Of Active Matrix Metalloproteinases (Mmps) Using Maldi Imaging Ms, Sasirekha Muruganantham

Graduate Theses and Dissertations

Biomaterial implantation induces the foreign body response (FBR). Development of longer-term implants relies on the thorough understanding of the FBR. The progression of the FBR is regulated by a number of biomolecules including cytokines, chemokines, and matrix metalloproteinases (MMPs). The nature of the FBR requires the spatial and temporal regulation of these mediators. MMPs are an extremely large and diverse group of enzymes that play key roles in regulating the FBR. Precise spatiotemporal regulation of MMPs defines their proteolytic activities. The aim of this project is to develop a new bioanalytical method to visualize the localization of active MMPs at …

Teachers' Perceptions Toward The Secondary Physical Education Program In The State Of Kuwait, Khaled A. Al-Kandari

Graduate Theses and Dissertations

The purpose of this research was to determine the perceptions of physical education teachers and supervisors toward the secondary physical education program in eight domains in the State of Kuwait. Stratified and cluster sampling were used to select two schools of female teachers and two schools of male teachers from each district (6 districts); therefore, 24 schools were selected randomly. One hundred thirty-eight physical education teachers were selected and 66 supervisors were selected. A four-point rating scale (i.e., strongly disagree to strongly agree) and open-ended questions were included in the survey. Cronbach's alpha reliability, descriptive statistics, and independent sample t …

Application Of The Empirical Mode Decomposition On The Characterization And Forecasting Of The Arrival Data Of An Enterprise Cluster, Linh Bao Ngo

Graduate Theses and Dissertations

Characterization and forecasting are two important processes in capacity planning. While they are closely related, their approaches have been different. In this research, a decomposition method called Empirical Mode Decomposition (EMD) has been applied as a preprocessing tool in order to bridge the input of both characterization and forecasting processes of the job arrivals of an enterprise cluster. Based on the facts that an enterprise cluster follows a standard preset working schedule and that EMD has the capability to extract hidden patterns within a data stream, we have developed a set of procedures that can preprocess the data for characterization …

The Design, Synthesis And Application Of A Novel Class Of N-Heterocyclic Carbene Catalysts, Abigail Lynn Hubbard

Graduate Theses and Dissertations

A copper carbenoid representative of a novel class of N-heterocyclic carbene (NHC) catalysts has been synthesized. This compound was characterized by X-ray crystallography and was found to confirm the rationale of our synthetic design: The C2-symmetric structure places four stereocenters in close proximity (<5Å) to the reactive site of the carbene via a trans-annular gearing effect. The copper carbenoid was found to catalyze the hydrosilylation of prochiral ketones with superb selectivity in high yield.

Improvements On Just-About-Right (Jar) Scales As Product Optimization Tools Using Kano Modeling Concepts, Bangde Li

Graduate Theses and Dissertations

Attribute Kano characteristics are useful in product design to prioritize development efforts. However, attribute Kano characteristics have not been discussed and applied to product optimization when using Just-About-Right (JAR) scales. Product optimizations without identifying attributes Kano characteristics can be misleading. The two objectives in this research were: 1. Determine attribute Kano categories using a modified classic Kano classification methodology. 2. Propose a method to measure attribute performance and identify attribute Kano characteristics to direct product optimization. Two methodologies of attribute Kano classification were investigated. In experiment one, a modified classic Kano methodology was employed to determine attribute Kano categories through …

High Performance Geospatial Analysis On Emerging Parallel Architectures, Seth Warn

Graduate Theses and Dissertations

Geographic information systems (GIS) are performing increasingly sophisticated analyses on growing data sets. These analyses demand high performance. At the same time, modern computing platforms increasingly derive their performance from several forms of parallelism. This dissertation explores the available parallelism in several GIS-applied algorithms: viewshed calculation, image feature transform, and feature analysis. It presents implementations of these algorithms that exploit parallel processing to reduce execution time, and analyzes the effectiveness of the implementations in their use of parallel processing.

Analyzing Spring Freeze Impacts On Deciduous Forest Productivity Using Modis Satellite Imagery, Karl Lintvedt

Graduate Theses and Dissertations

The impacts of an April 2007 spring freeze event on the productivity of deciduous broadleaf forest were analyzed using geographic information system (GIS) tools. Forest productivity was modeled using the Enhanced Vegetation Index (EVI), as recorded by the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite sensor. Measures of spatial autocorrelation were used to quantify the degree of spatial congruence between a map depicting the severity of the freeze event, and maps modeling forest productivity throughout the year. The results show a geographic correlation between the unseasonably low minimum temperatures sustained during the freeze and the unusually low forest productivity that followed. …

Factors Influencing Teaching Efficacy Among Kansas Career And Technical Education Faculty, Douglas Lee Younger

Graduate Theses and Dissertations

The purpose of this study was to examine the levels of teaching efficacy among postsecondary career and technical education faculty at Kansas technical and community colleges. Postsecondary career and technical education faculty at Kansas technical and community colleges were asked to complete an instrument designed to measure their levels of teaching efficacy based upon a modified version of the Teachers' Sense of Efficacy Scale, originally developed by Woolfolk and Hoy (1998). The entire population of postsecondary career and technical education faculty from Kansas technical and community colleges (N=726) were surveyed and a total of n=181 (24.9%) completed the instrument. Data …

Exploring First Generation African American Graduate Students: Motivating Factors For Pursuing A Doctoral Degree, Stephanie G. Adams

Graduate Theses and Dissertations

The purpose for conducting the study was to examine the factors that motivate African-American first-generation students to pursue doctoral education at a four-year public university. There has been little research on the influence academic or non-academic factors have on first-generation graduate student motivation. Similarly, little research exists that explored how factors might vary by ethnicity. Based on the projected increase of post-baccalaureate enrollment each year (Aud, Hussar, Planty, Snyder, Bianco, Fox, Frohlich, Kemp, Drake, 2010), first-generation African-Americans will become more interested in attending graduate school. It is important to gain a better understanding of the factors and influences that impact …

Dynamics And Catalytic Resolution Of Selected Chiral Organolithiums, Timothy Kum Beng

Graduate Theses and Dissertations

One of the most important developments of the last decade has been the emergence of new methods to dynamically resolve racemic organolithiums using stoichiometric amounts of the chiral ligand. When this concept is implemented successfully, it obviates the need for covalently attached chiral auxiliary based methods, asymmetric deprotonation, and asymmetric synthesis of a precursor stannane as ways to access enantioenriched organolithium compounds for use in asymmetric synthesis. Since certain electrophiles consume the chiral ligand, it is desirable to render this process catalytic in the chiral ligand.

As part of a larger study on the amenability of chiral organolithiums to a …

Subcritical Water Hydrolysis Of Whey Proteins, Ashley Dawn Espinoza

Graduate Theses and Dissertations

Hydrolyzing food by-products is a unique approach to potentially increase by-product value and reduce waste. An abundant by-product of cheese production, whey, contains all essential amino acids and some distinctive peptides with functional and nutraceutical properties. Typically, proteins from whey are tailored for specific uses by chemical or enzymatic hydrolysis; however, subcritical water hydrolysis is a novel alternative used successfully to hydrolyze various substrates. Nevertheless, minimal research exists on: (1) the hydrolysis of whey protein; (2) the incorporation of additives; (3) the hydrolysis of whole whey; and (4) the production of volatiles when using subcritical water hydrolysis.

Therefore, whey protein …

Sublime Beauty & Horrible Fucking Things - The Finer Worlds Of Warren Ellis, William James Allred

Graduate Theses and Dissertations

This work constitutes an in-depth discussion of the muted postmodern characteristics of contemporary comics writer and novelist Warren Ellis, highlighting his major long-form works within comics, Planetary, Transmetropolitan, StormWatch, and The Authority, as well as several shorter works such as Ocean, Orbiter, and Global Frequency. In addition, Ellis is situated within the British science fiction tradition, specifically, the British Boom movement which contains other comics writers such as Neil Gaiman and Alan Moore.

Nitrogen Retention And Denitrification In Reservoirs, Erin Grantz

Graduate Theses and Dissertations

Studies coupling direct measurements of micro-scale nitrogen (N) cycle processes with ecosystem-scale flux estimates are needed to determine N retention hotspots within river networks, where up to 50% of terrestrial loading to aquatic systems is retained. This study examined the role of denitrification, a microbially-mediated reactive N removal pathway, in ecosystem-scale N retention in 3 small (< 1 km2), shallow flood-control reservoirs. Annual reservoir N retention was estimated through mass balance modeling of system inputs and outputs. Annual denitrification rates were estimated by combining multiple measurements of seasonal, habitat-specific dinitrogen gas (N2) fluxes. Annual reservoir N retention ranged from 14 - 19 g m-2 in the reservoirs, while reactive N removal through denitrification was 13 - 25 g m-2. Denitrification efficiency, or the portion of the retained N load that was denitrified, was high relative to other lentic systems and was > 100% at 2 sites. Previous lentic denitrification studies may have underestimated denitrification efficiency by not considering water column denitrification, which was 50% of total denitrification at one study reservoir. However, not all potential inputs, most importantly biological N2 fixation, were included in this …

Mathematically Gifted Students' Experiences Of Challenge With Cognitively Guided Instruction, Kim Krusen Mccomas

Graduate Theses and Dissertations

This study examined to what extent and in what ways mathematically gifted students were challenged in two elementary classrooms taught by exemplary teachers using the principles of Cognitively Guided Instruction (CGI). The two case studies included a third grade class and a fourth/fifth split grade class, with five mathematically advanced participants from each grade. A top tier and a second tier of mathematically advanced students were identified, with the top tier of five students identified as mathematically gifted. Classroom observations of CGI math lessons, interviews with students and teachers, and analysis of students' problem-solving strategies were conducted over a five …

Modeling Of Sic P-Channel Insulated Gate Bipolar Transistors (Igbts), Mahmood Saadeh

Graduate Theses and Dissertations

A new physics-based IGBT compact model has been developed for circuit simulation of silicon (Si) or silicon carbide (SiC) devices. The model accurately predicts the steady-state output, transfer and switching characteristics of the IGBT under a variety of different conditions. This is the first IGBT model to predict the behavior of p-channel SiC IGBTs. Previous work on IGBT models has focused on Si n-channel IGBTs [1-3]. This unified model is not limited to SiC p-channel IGBTs; the user has the option to select between Si or SiC, and n-channel or p-channel, making it the first IGBT model that captures the …

Geospatial Tools And Techniques For Watershed Management Using Swat 2009, Naresh Pai

Graduate Theses and Dissertations

In this study, geospatial tools and techniques were developed to support specific aspects of watershed pollution management, such as quantifying land-use change (LUC) impacts, prioritizing subwatersheds, and communicating field-scale impacts, using the soil and water assessment tool 2009 (SWAT 2009) model.

For the land-use change objective, a geospatial tool titled SWAT2009_LUC was developed that enables SWAT modelers to prepare specific input files for simulating concurrent land-use changes during the SWAT 2009 model simulations. Testing of the tool for the Illinois River Drainage Area in Arkansas (IRDAA) watershed showed that the tool accurately represented temporal land-uses within the model. Model simulations …

Modeling And Characterization Of P-Type Silicon Carbide Gate Turn Off Thyristors, Osama Shihadeh Saadeh

Graduate Theses and Dissertations

Silicon carbide (SiC) power semiconductor devices have emerged in the past decade as the most promising technology for next generation power electronic applications ranging for electric vehicles to grid-connected power routing and conversion interfaces. Several devices have been developed, and even some have been released commercially, including diodes, MOSFETs, JFETs, thyristors, gate turn-off thyristors, and IGBTs. The model development, characterization and experimental validation of SiC p-type Gate Turn-off Thyristors (GTO) is presented in this work. The GTO device in this work is being used as part of a SiC-based solid-state fault current limiter under development at the University of Arkansas' …

Defining, Executing And Visualizing Representative Workflows In A Retail Domain, May Zeineldin

Graduate Theses and Dissertations

Our lives are filled with routine activities that we do more or less on auto-pilot such as driving to work and cooking. This thesis explores a workflow representation as a way to represent such activities of daily living. The domain of a retail store environment is used. Workflows are initially expressed in a structured English representation, then translated into a Petri net notation and implemented in mix of Petri nets, Lua, and C so that the resulting workflows can be displayed as the actions of collections of avatarbots (avatars controlled by programs) in a 3D virtual world, Second Life. One …

Design Of A Low Noise Amplifier For Wireless Sensor Networks, Ting Liu

Graduate Theses and Dissertations

CMOS technology becomes important in Radio Frequency (RF) communication systems which include both a receiver and a transmitter. In a high performance radio receiver, the Low Noise Amplifier (LNA) is the first circuit, and its noise performance dominates the entire receiver. Depending upon the system in which they are used, LNAs can be designed according to various topologies and structures. The LNA needs to have matched input impedance, and at the same time it should amplify the small amplitude input signal without adding too much noise and still have the minimal power consumption. It also needs a good interface with …

Cognitive Agendas And Legal Epistemology, Danny Marrero

Graduate Theses and Dissertations

The domain of legal epistemology is defined from two alternative perspectives: individual epistemology and Social epistemology. Since these perspectives have different objects of evaluation, their judgments privilege and exclude different sets of information. While methodological individualism is concerned with justified beliefs of individual knowers, the Social angle focuses on the institutional conditions of knowledge. I will show that the information that is respectively excluded by both the individual and the Social concepts of legal epistemology weaken their respective evaluations. With this in mind, I will explore one new option of defining legal epistemology. This alternative is more comprehensive, in the …

The Effects Of Scheduling On Criterion-Referenced Assessments In Arkansas High Schools, Sheila Marie Trinkle

Graduate Theses and Dissertations

The purpose of this study is to examine the differences in achievement on the end of course assessment in Geometry and the Grade 11 Literacy exam administered to students in Arkansas during the 2005-2006 and 2006-2007 school years. The three main types of scheduling are the traditional schedule with seven or eight periods; the A/B, or the alternating block; and the 4 x 4, or accelerated block. The traditional was utilized by 90% of schools in Arkansas during this time frame. The A/B block and 4 x 4 block were used almost equally, each representing approximately 5% of Arkansas schools. …

A Multiple Case Study Of Principals' Instructional Leadership In "Level 5" Schools Of Excellence For Improvement, Janice V. Mccoy

Graduate Theses and Dissertations

After 28 years of federal and state policy development, regional and local initiatives and various budgetary appropriations, the status of American schools continues to decline. Lyne (2001) reported that Finland, Japan and Korea had the world's highest literacy in reading, math, and science, while the United States ranked 15 in reading literacy, 19 in mathematical literacy, and 14 in scientific literacy. Many factors may contribute to the decline in America's schools. However, with the prevailing economic decline in the United States schools continue to struggle with student achievement, especially students with who are low socio-economic. In addition, to meeting the …

Studies Toward The Development Of A Microelectrode Array For Detection Of Dopamine Through Redox Cycling, Anupama Aggarwal

Graduate Theses and Dissertations

Redox cycling is an electrochemical technique that cycles the reversible redox species between its oxidative states repeatedly on generator and collector electrodes. Two or more individually-addressable microelectrodes located close to each other allow redox cycling to be possible. Electrochemical behavior of a biologically important molecule, dopamine is examined under redox cycling conditions. To our knowledge, this is the first report on detection of physiological concentration of dopamine in presence of up to 100 times excess ascorbate with the use of redox cycling, without the involvement of polymer coating such as Nafion®.

Microfabrication was used to produce different geometries (parallel bands …

Water Quality Trends For Section 319 Priority Watersheds In Northwest Arkansas, 1997-2010, Bryan William Bailey

Graduate Theses and Dissertations

Northwest Arkansas contains two Section 319 Priority Watersheds that the Arkansas Natural Resources Commission (ANRC) has identified as being impacted by point and nonpoint sources of pollution (i.e., phosphorus, nitrogen, and sediment), and the Arkansas Water Resources Center (AWRC) has monitored the water quality at several sites within these watersheds. Water-quality data has been collected over the last decade within the Illinois River Watershed (HUC #11110103) and the Upper White River Basin (Beaver Reservoir HUC# 11010001), each watershed containing three sampling sites. The Illinois River Watershed sites are located on the Illinois River, Osage Creek, and Ballard Creek, and the …

Assessing Ageing At Beaver Reservoir, Northwest Arkansas: Limnological, Geochemical & Paleolimnological Approach, Byron Anthony Winston

Graduate Theses and Dissertations

Access to potable water has been arguably one of the most important requisites for the advancement of human civilization on earth. As a result, man in his infinite wisdom devised the dam and formed reservoirs, (man- made lakes), to exploit water resources at will. In all natural lakes and reservoirs changes occur in the water quality parameters as it relates to chemical nutrients, temperature and turbidity over time. These changes are collectively referred to as "Reservoir Ageing", of which sedimentation and eutrophication are primary. Reservoir Ageing has consequences which adversely affect and defeat many of the intended uses of the …