Digital Commons Network^™

Anxiety And Sleep Disorder Comorbidity: Affecting The College Students' Performances, Amanda Rhenee Grimes

Graduate Theses and Dissertations

The purpose of this study is to determine the effects that anxiety disorders and sleep disorders have on students' academic performance. The prevalence of both disorders is rising in the college student population. This study examines those who have been physician diagnosed with the one or both of the disorders and how the students' grade point average (GPA) is affected.

The National College Health Assessment was used for data collection; this survey assesses college students' health habits, behaviors, and perceptions. The sample was comprised of 57 institutions representing every region in the U.S. totaling 34,208 participants. Data was acquired through …

Use Of Ultra High Vacuum Plasma Enhanced Chemical Vapor Deposition For Graphene Fabrication, Shannen Adcock

Graduate Theses and Dissertations

Graphene, what some are terming the "new silicon", has the possibility of revolutionizing technology through nanoscale design processes. Fabrication of graphene for device processing is limited largely by the temperatures used in conventional deposition. High temperatures are detrimental to device design where many different materials may be present. For this reason, graphene synthesis at low temperatures using plasma-enhanced chemical vapor deposition is the subject of much research. In this thesis, a tool for ultra-high vacuum plasma-enhanced chemical vapor deposition (UHV-PECVD) and accompanying subsystems, such as control systems and alarms, are designed and implemented to be used in future graphene growths. …

Mitigating Insider Threat In Relational Database Systems, Qussai Yaseen

Graduate Theses and Dissertations

The dissertation concentrates on addressing the factors and capabilities that enable insiders to violate systems security. It focuses on modeling the accumulative knowledge that insiders get throughout legal accesses, and it concentrates on analyzing the dependencies and constraints among data items and represents them using graph-based methods. The dissertation proposes new types of Knowledge Graphs (KGs) to represent insiders' knowledgebases. Furthermore, it introduces the Neural Dependency and Inference Graph (NDIG) and Constraints and Dependencies Graph (CDG) to demonstrate the dependencies and constraints among data items. The dissertation discusses in detail how insiders use knowledgebases and dependencies and constraints to get …

High Frequency Characterization Of Carbon Nanotube Networks For Device Applications, Emmanuel Decrossas

Graduate Theses and Dissertations

This work includes the microwave characterization of carbon nanotubes (CNTs) to design new CNTs-based high frequency components. A novel developed method to extract the electrical properties over a broad microwave frequency band from 10 MHz to 50 GHz of carbon nanotubes (CNTs) in a powder form is performed. The measured scattering parameters (S-parameters) with a performance network analyzer are compared to the simulated one obtained from an in-house computed mode matching technique (MMT). An optimized first order gradient method iteratively changes the unknown complex permittivity parameters to map the simulated S-parameters with the measured one until convergence criteria are satisfied. …

Role Of Vegetation And Environmental Characteristics On Slope Stability In Northwest Arkansas, Michael Maguigan

Graduate Theses and Dissertations

Slope failure continues to pose risks to society because knowledge of environmental factors and their interactions are unclear and possibly misunderstood. This misunderstanding leads to generalizations about slope failure susceptibility mapping, despite knowing that slope failures are likely the result of an extensively complex set of interactions among a number of environmental, edaphic, and geomorphic characteristics. Therefore a series of experiments were conducted to investigate the effects of slope, soil texture, vegetation cover, bedrock permeability, and compaction,. A wooden flume with a slope face 1 m wide by 1.5 m long with a 10 cm toe was constructed to contain …

Fabrication Of Vertical Silicon Nanowires Through Metal Assisted Deposition, Matthew Garett Young

Graduate Theses and Dissertations

Controlled and ordered growth of Si nanowires through a low temperature fabrication method compatible with CMOS processing lines is a highly desirable replacement to future electronic fabrication technologies as well as a candidate for a low cost route to inexpensive photovoltaics. This stems from the fact that traditional CMOS based electronics are hitting physical barriers that are slowing the Moore's Law trend as well as the demand for an inexpensive solar cell technology that can obtain grid parity. A fractional factorial growth study is presented that compares the growth of Au and Al catalyzed Si nanowires at temperatures ranging from …

Pointwise Schauder Estimates Of Parabolic Equations In Carnot Groups, Heather Arielle Griffin

Graduate Theses and Dissertations

Schauder estimates were a historical stepping stone for establishing uniqueness and smoothness of solutions for certain classes of partial differential equations. Since that time, they have remained an essential tool in the field. Roughly speaking, the estimates state that the Holder continuity of the coefficient functions and inhomogeneous term implies the Holder continuity of the solution and its derivatives. This document establishes pointwise Schauder estimates for second order parabolic equations where the traditional role of derivatives are played by vector fields generated by the first layer of the Lie algebra stratification for a Carnot group. The Schauder estimates are shown …

Stratigraphy And Provenance Of Shallow Sandstones Endountered In Wells In Townships 9 And 10 North, Ranges 6 And 7 West, White County, Arkansas, Lacie Knight

Graduate Theses and Dissertations

Paleozoic formations in western Arkansas have been well-studied; however, they are not well-understood in the eastern part of the state. The study area encompasses Townships 9. N. and 10. N., Ranges 6. W. and 7. W. in north-central White County, Arkansas. This area is at the intersection of four physiographic provinces as defined by the Arkansas Geologic Survey- the Ozark Plateaus, the Arkansas River Valley, the Ouachita Mountains, and the Mississippi Alluvial Plain. Interpretations of the surface unit in the area disagree. The Arkansas Geologic Map shows that the Morrowan Hale Formation crops out in the area; however, various petroleum …

Extending The Hybridthread Smp Model For Distributed Memory Systems, Eugene Anthony Cartwright Iii

Graduate Theses and Dissertations

Memory Hierarchy is of growing importance in system design today. As Moore's Law allows system designers to include more processors within their designs, data locality becomes a priority. Traditional multiprocessor systems on chip (MPSoC) experience difficulty scaling as the quantity of processors increases. This challenge is common behavior of memory accesses in a shared memory environment and causes a decrease in memory bandwidth as processor numbers increase. In order to provide the necessary levels of scalability, the computer architecture community has sought to decentralize memory accesses by distributing memory throughout the system. Distributed memory offers greater bandwidth due to decoupled …

A Family Affair: The Pre-Kansas Saga Of James Henry Lane, James Robert Bird

Graduate Theses and Dissertations

Historian Craig Miner suggests that territorial Kansas between 1854 and 1861 was "a nursery of weird and manic figures." Foremost among the weird and manic figures of Kansas history stands James Henry Lane, formerly a U.S. congressman from Indiana, and destined to become one of Kansas' first pair of senators. Writing at the midpoint of the twentieth century, Albert Castel pronounced Jim Lane "the most colorful and fascinating personality in the history of Kansas," adding that "Very likely, too, he was mentally unbalanced and paranoid."

Yet, James H. Lane never set foot on Kansas soil until he was well into …

Electrospun Polycaprolactone Nanofiber Scaffolds For Tissue Engineering, Andreas Haukas

Graduate Theses and Dissertations

Stem cell and tissue engineering offer us with a unique opportunity to research and develop new therapies for treating various diseases that are otherwise incurable using traditional medicines. However, development of these new therapies replies upon the establishment of in vitro cell culture and differentiation systems that mimic in vivo microenvironments required for cell-cell and cell-ECM interaction. The development of these cell culture systems depends upon the identification of appropriate biomaterials and cell sources. Biomaterials should be carefully selected and fabricated into scaffolds for supporting cell growth and differentiation. In this study, we explored the fabrication of 3D electrospun nanofiber …

Navigation And Accessibility For Persons With Disabilities: An Anthropological Study Using Gis On The University Of Arkansas Campus, Deborah Jean Raiees-Dana

Graduate Theses and Dissertations

The University of Arkansas was founded in 1871 on the top of a hill overlooking the Ozark Mountains, resulting in a campus that has steep slopes and numerous historical buildings that were not designed with ADA regulations in mind. This makes getting around campus especially difficult for students with limited mobility, and no campus maps exist that include handicapped accessibility features to help navigate the terrain and limited parking options. This study examines this issue using a holistic approach that explores cultural and technological factors to produce a map of the Historic Core District of campus.

Geographical Information Systems enable …

Assessment Of Land Use Suitability Based On Water Erosion Susceptibility In Medium-Sized Urban Areas Of The Metropolitan Region Of Santiago, Central Chile, Roberto Fernandez

Graduate Theses and Dissertations

Urban areas constitute complex spatial entities where biophysical and socioeconomic environments interact through processes that determine the distribution of land use in the territory. Given Chile's variety of landscapes, water erosion, and mass movement, and rapid expansion of its medium-sized cities, straightforward techniques for assessment of land use suitability are essential. Through evaluation of water erosion susceptibility, it is possible to efficiently determine suitability of land use in medium-sized cities and their adjacent environments. The adaptation and application of the Erosion Response Units (ERU) concept (Märker et al., 2001) in the cities of Colina and Melipilla, Metropolitan Region of …

Components Of Effective Teacher Induction Programs And The Impact Of Experienced Mentors, Craig P. Mcbride

Graduate Theses and Dissertations

Based on data from the 2007-08 Schools and Staffing Survey (SASS), 2008-09 Teacher Follow-up Survey (TFS) and 2009-10 Beginning Teacher Longitudinal Study (BTLS) datasets, this study examined a prediction model for new teacher retention that combined variables from both the presence of induction program components and mentoring traits. New teacher retention was selected as an important criterion because attrition causes a large financial burden on already budget-limited districts, and teacher turnover impacts teacher effectiveness and student learning. Results of a logistic regression analysis indicated that the presence of an induction program (W1T0220), the presence of a mentor (W2MNTYN), the use …

Insider Threat Mitigation Models Based On Thresholds And Dependencies, Harini Ragavan

Graduate Theses and Dissertations

Insider threat causes great damage to data in any organization and is considered a serious issue. In spite of the presence of threat prevention mechanisms, sophisticated insiders still continue to attack a database with new techniques. One such technique which remains an advantage for insiders to attack databases is the dependency relationship among data items. This thesis investigates the ways by which an authorized insider detects dependencies in order to perform malicious write operations. The goal is to monitor malicious write operations performed by an insider by taking advantage of dependencies. A term called `threshold' is associated with every data …

Mathematical Modeling Of Fluid Spills In Hydraulically Fractured Well Sites, Oluwafemi Michael Taiwo

Graduate Theses and Dissertations

Improved drilling technology and favorable energy prices have contributed to the rapid pace at which the exploitation of unconventional natural gas is taking place across the United States. As a natural gas well is being drilled, reserve pits are constructed to hold the drilling fluids and other materials returned from the drilling process. These reserve pits can fail, and when they do, plant and animal life of the surrounding area may be adversely affected. This project develops a screening tool for a suitable location for a reserve pit. This work will be a critical piece of the Infrastructure Placement Analysis …

Factors Influencing The Improved Academic Success In Literacy At The Knowledge Is Educatpower Program School In The Delta Region According To Administrator, Teacher, And Student Perceptions: Case Study, Kimberly Jonetta Brown

Graduate Theses and Dissertations

The purpose of this study was to explore the factors that have influenced the literacy success of the Knowledge is Power Program (KIPP) students in the low-income, poverty stricken Delta Region of a mid-south state. The study examined the progress made since the implementation of the KIPP Program and the influence the program has made upon student achievement in literacy, at the KIPP Middle and High Schools, according to administrator, teacher, and student perceptions. The study explored what factors are influencing the improvement of previously at-risk students. The study adopted the research of Gene Bottoms' High Schools that Work Initiative …

Understanding How Adult Educators Apply Andragogy In A Correctional Educational Setting: A Case Study, Carl Jenkins Stephen

Graduate Theses and Dissertations

Yes as your words

The purpose of this case study was to examine how adult educators apply the six principles of andragogy, by Malcolm Knowles with adult learners in a correctional educational GED program. The following six principles label adult learners as people who: (1) Are self-directed and intrinsically motivated learners; (2) Bridge life experiences with old knowledge with new learning; (3) Are goals-driven learners; (4) Expect experiences to be relevant to them; (5) Are practical learners; and (6) Want respect (Knowles, 1984). The study included qualitative research. There were nine participants involved in this study. Conversational interviews were conducted …

Three-Dimensional Scene Reconstruction Using Multiple Microsoft Kinects, Matt Miller

Graduate Theses and Dissertations

The Microsoft Kinect represents a leap forward in the form of cheap, consumer friendly, depth sensing cameras. Through the use of the depth information as well as the accompanying RGB camera image, it becomes possible to represent the scene, what the camera sees, as a three-dimensional geometric model. In this thesis, we explore how to obtain useful data from the Kinect, and how to use it for the creation of a three-dimensional geometric model of the scene. We develop and test multiple ways of improving the depth information received from the Kinect, in order to create smoother three-dimensional models. We …

Implementation Of Orthogonal Frequency Division Multiplexing With Fpga, Qi Hao Yang

Graduate Theses and Dissertations

In recent years, there have been dramatic shifts in cellular and telecommunication industries. As smartphones are dominating on the cellphone market, more and more people use these mobile devices to access internet either through third generation network or IEEE802.11 wireless local area network. Orthogonal frequency division multiplexing (OFDM) has been widely used in IEEE802.11 wireless local area network and fourth generation network. This paper will focus on the design and implementation of an Orthogonal Frequency Division Multiplexing system on field-programmable gate array (FPGA). The major components of an OFDM system include a modulator, an N-input inverse Fast Fourier Transform (IFFT), …

Silicon Germanium Sram And Rom Designs For Wide Temperature Range Space Applications, Matthew Barlow

Graduate Theses and Dissertations

This thesis presents a design flow from specifications and feature requirements to embeddable blocks of SRAM and ROM designs from 64 bytes to 1 kilobyte that are suitable for lunar environments. The design uses the IBM SiGe 5AM BiCMOS 0.5 micron process for a synchronous memory system capable of operating at a clock frequency of 25 MHz. Radiation mitigation techniques are discussed and implemented to harden the design against total ionizing dose (TID), single-event upset (SEU), and single-event latch-up (SEL). The memory arrays are also designed to operate over the wide temperature range of -180 °C to 125 °C. Design, …

Perceived Impact Of Quality In A 21st Century Community Learning Center Out-Of-School Time Program: A Case Study, Patricia Ann Wright

Graduate Theses and Dissertations

Concern for the safety, education and well-being of children during out-of-school time is helping to change the landscape and priorities of families, educators and policy-makers. Changes in family structure and society have presented the need for quality out-of-school time programs. The changing family structure caused by both parents working outside the home, the advent of the single-parent household, the necessity of federally mandated standardized testing for student achievement, certain criminal activities and the expanding population of children have contributed to the question of how to protect children and enrich their lives during out-of-school time hours. The purpose of this intrinsic …

Recognizing Patterns In Transmitted Signals For Identification Purposes, Baha' A. Alsaify

Graduate Theses and Dissertations

The ability to identify and authenticate entities in cyberspace such as users, computers, cell phones, smart cards, and radio frequency identification (RFID) tags is usually accomplished by having the entity demonstrate knowledge of a secret key. When the entity is portable and physically accessible, like an RFID tag, it can be difficult to secure given the memory, processing, and economic constraints. This work proposes to use unique patterns in the transmitted signals caused by manufacturing differences to identify and authenticate a wireless device such as an RFID tag. Both manufacturer identification and tag identification are performed on a population of …

Nutrient Dynamics In Stormwater Runoff From Green Roofs With Varying Substrate, John Michael Fohner

Graduate Theses and Dissertations

One major concern with urban development is the increasing amount of stormwater runoff from large expanses of impervious surfaces. These impervious surfaces reduce the ability of stormwater to infiltrate into the soil and eventually groundwater, which leads to greater amounts of surface runoff. Green technology serves as a viable solution to many of the environmental problems presented by modern development. Fifteen mock, extensive green roofs were built in the fall of 2008 at the Watershed Research and Education Center in Fayetteville, Arkansas. The goals of this project were to (1) measure the amount of stormwater runoff from varying treatments and …

Identifying Optimal Cellulosic Biomass Feedstock Supply Areas For Potential Biorefineries In Arkansas, Mark Cooper

Graduate Theses and Dissertations

In February 2010, the U.S. Environmental Protection Agency released the revised Renewable Fuel Standard (RFS2), mandating at least 36 billion gallons of renewable fuels to be produced annually in America, and blended into all on/off road, locomotive, and marine gasoline and diesel by the year 2022. America's existing biorefineries fall significantly short of being able to meet this mandate, resulting in the need for rapid expansion in the near future if this goal is to be met. The state of Arkansas has abundant resources to offer the renewable energy industry, if properly utilized. The goal of this thesis is to …

Public Parks And Private Ideologies: Building Nineteenth-Century British National Identity Through Landscape, Laura Swaim Witherington

Graduate Theses and Dissertations

This project examines how nineteenth-century landscape theories shaped national identity and were influenced by it. Predominant is an investigation of how the desire for a more egalitarian class structure underlies the changes in British landscape design from an attachment to classical exclusivity through pastoral tropes to a limited acceptance of middle and working classes within public landscapes that represented patriotic values. Although poetic works inform the study, novel-length fiction and non-fiction prose and periodicals are also a primary source of consideration. Novels demonstrate how fictional geography generates the constructs of national ideology, and although canonical works typically referenced in studu …

Reappraising The Land Behind Baghdad: Using Corona Satellite Imagery To Reassess The Archaeological Landscape Of The Diyala Plain, Iraq, James Henry Wesolowski

Graduate Theses and Dissertations

High-resolution low-cost declassified CORONA spy satellite imagery is used to detect archaeological sites and relict canals in the Diyala Plain to the east of Baghdad, Iraq. This project seeks to improve upon the ground survey conducted there in the 1950s by providing better geographic control and discovering sites and canals that were not included in the original survey. CORONA imagery provides a sub-2-meter spatial resolution and was acquired shortly after the original ground survey was conducted, providing an excellent medium for comparison. CORONA imagery is subject to significant spatial distortions because of its camera technology and the LPS package for …

Fluorescence Enhancement Using One-Dimensional Photonic Band Gap Multilayer Structure, Jian Gao

Graduate Theses and Dissertations

Fluorescence enhancement using one-dimensional photonic band gap (1DPBG) multilayer structures is demonstrated in this dissertation. Designed with proper refractive indices and thicknesses, the alternating high and low index multilayer thin film structures combine photonic crystal resonance and omni-directional reflection together to enhance the excitation light irradiance and improve the collection efficiency of the fluorescent emission light with different polarizations. Gallium phosphide was chosen as the high index material and its fabrication process was optimized. The field enhancement effect was experimentally confirmed for two designs with achieved enhancement factors of 50̃69 folds corresponding to TE and TM waves. The omni-directional reflection …

Perception Of Aquifer Depletion And The Effects Of Land Use Change Across The Madaba Plain, Jordan, Mohammad Salem

Graduate Theses and Dissertations

In Jordan, demand for water for agricultural purposes has put a high strain on aquifer resources. Water mining, erosion, and desertification have all increased as global temperatures rise. This along with fragmentation of the landscape have altered the environment in a profound way. The Madaba Plain was chosen for this study due to the agricultural activities that take place there, as well as the proximity to a number of population centers. The purpose of the study is to examine how fragmentation of irrigated landscape has affected the aquifers underneath, while taking into account perceptions of risk of the local population. …

Removal Of Disinfection By-Product Precursors Using Magnetic Ion Exchange (Miex(R)): The Effects Of Ph And Source Water Variability, Sarah Cousins

Graduate Theses and Dissertations

Disinfection by-products (DBPs) form as an unintended result of drinking water disinfection, from chemical reactions between disinfectants (e.g., free chlorine) and naturally occurring dissolved organic matter (DOM). At present, 11 DBPs are regulated in treated drinking waters due to potential adverse health effects, including four trihalomethanes (THMs). Despite nearly 40 years of DBP research, compliance with DBP regulations remains a challenge for many drinking water treatment plants (DWTPs), including the four DWTPs located on the Beaver Lake Reservoir in Northwest Arkansas. Due to the high net negative surface charge on DOM, anion exchange is one potentially viable method for removing …