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Habitat Modeling Of Three Endemic Crayfish Species In The Black River Drainage Of Missouri And Arkansas: Factors Affecting Distribution And Abundance, Matthew Stephen Nolen

Graduate Theses and Dissertations

The Ozark faunal region of Missouri and Arkansas harbors a high level of aquatic biological diversity, especially in regards to endemic crayfish. Orconectes eupunctus, Orconectes marchandi, and Cambarus hubbsi are three such endemics that are threatened by a limited natural distribution and the invasions of Orconectes neglectus. I sought to determine how natural and anthropogenic factors influence these three species across multiple spatial scales. Local and landscape data were used in decision tree analyses (CART) to determine their influence effect on presence/absence and density of the three species. Predictive models were validated using k-fold cross validation. O. eupunctus presence was …

Stratigraphic Variations In The Carboniferous Section Across The Arkansas-Oklahoma State Line Arch, Tyler Dean Engelhardt

Graduate Theses and Dissertations

The State Line Arch is represented by a structural high that trends through the study area in a loose alignment with the Arkansas-Oklahoma state line. Evidence of the arch extending further to the north includes a structural high and stratigraphic variation at an outcrop on Highway 59 near Evansville Mountain in Crawford County, Arkansas. The exact timing of the formation of the arch remains undetermined, but upper Devonian thinning at the top of the arch indicates the structure is pre-Mississippian. The reason for the development of the arch is poorly understood, but evidence linking Mississippian-aged Waulsortian mounds to Precambrian Spavinaw …

Master Principals' Perceptions Of The Impact Of The Arkansas Leadership Academy's Master Principal Program On Leadership Practices, School Cultures And Student Achievement, Diana Peer

Graduate Theses and Dissertations

A qualitative dissertation study was conducted to examine the impact of the Arkansas Leadership Academy's Master Principal Program through the perspective of those who have completed the entire program and attained designation as a Master Principal. A logic model for the Master Principal Program offered a context for the study. A review of relevant literature provided the identification of gaps in the research which included limited findings for a program comparable to the Master Principal Program. Research methods for this phenomenological study were explained. The research sample included Master Principals, as of 2011. Interviews and a focus group using collaborative …

Pulse Sharpening Effects Of Thin Film Ferroelectric Transmission Lines, Robert J. Sleezer

Graduate Theses and Dissertations

Advances in material science have resulted in the development of electrically nonlinear high dielectric thin film ferroelectrics, which have led to new opportunities for the creation of novel devices. This dissertation investigated one such device: a low voltage nonlinear transmission line (NLTL). A finite element simulation of ferroelectric transmission lines showed that NLTLs are capable of creating shockwaves. Additionally, if the losses are kept sufficiently low, it was shown that voltage gain should be possible. Furthermore, a method of accounting for material dispersion was developed. Results from simulations including material dispersion showed that temporal solitons might be possible from a …

Investigating The Sensitivity Of Goodness-Of-Fit Indices To Detect Measurement Invariance In The Bifactor Model, Jam Khojasteh

Graduate Theses and Dissertations

A Monte Carlo simulation study was conducted to evaluate the sensitivities of five commonly used goodness-of-fit indices to detect metric invariance properties of the bifactor model. The fit indices that performed the best in terms of power were Gamma and Mc. In addition, Gamma, Mc, CFI, and RMSEA all held Type I error to a minimum. However, only Gamma and CFI are recommended to use in the bifactor model because the other GOF indices have cutoff values that are too large. For Gamma and CFI values of -.026 to -.045 and -.004 to -.009, respectively indicate a lack of metric …

Inquiry-Based Instruction In The Social Studies: Successes And Challenges, Crystal Maree Beshears

Graduate Theses and Dissertations

The purpose of this study was to investigate teachers' perceptions, understanding, and use of inquiry-based instruction in the Social studies, to assess the impact of inquiry-based units on instruction, to detail implementation successes and challenges reported by teachers when implementing inquiry-based instruction, and to provide recommendations for future efforts. Teachers' perceptions of teaching and learning, particularly their beliefs about inquiry-based instruction, changed during the study. Throughout the study, teachers' perceptions and beliefs about teaching Social studies had an impact on how they planned, implemented and reflected on inquiry-based instruction. Many of the teachers changed their perceptions and began regularly teaching …

A Comparison Of Student Success By Faculty Qualifications, Kristine A. Garner

Graduate Theses and Dissertations

Providing the best qualified faculty to ensure the most successful student outcomes is a priority in higher education. The use of adjunct faculty in colleges and universities is continually increasing, especially for lower level courses. Previous research has come to conflicting conclusions regarding the quality of adjunct faculty. Indicators of student success were compared between part-time instructors with professional doctoral degrees and full-time instructors with academic doctoral degrees. Results of statistical analyses of both a comparison of final grade distributions and knowledge of course content determined that there were no significant differences between two comparable groups of students in a …

Mapping Xenophobic Violence In South Africa: Modeling Spatial Relationships Between Group Grievances And Opportunities To Measure The Propensity For Xenophobic Violence, Eric Holder

Graduate Theses and Dissertations

Xenophobia can be defined as the hatred or fear of foreigners or strangers or of their politics or culture (Ngwane et al., 2008). This sentiment reached its tipping point in urban areas across the Republic of South Africa in May 2008 when mass, widespread and systematic attacks against African non-nationals took place across the country. Although previous research agrees on who played the various roles during this crisis event (Everatt, 2010), little research has been carried out to create a predictive model to assess where future violence could occur based on a set of conflict indicators. The purpose of this …

Phenotypic Plasticity Of Rattlesnake Trophic Morphology, Matthew Thomas Smith

Graduate Theses and Dissertations

The trophic morphology of gape-limited predators constrains the shape and size of prey items they can ingest. Trophic morphology consists of any morphological feature that is involved in the handling and ingestion of food. Diet has a profound effect on the morphology of many gape-limited predators. Identifying how prey type and resource level affect the morphology of different populations is an essential step in understanding the mechanisms contributing to patterns of morphological diversity. Species interactions (Chapter 1) induce plasticity in morphology that can lead to increased fitness, morphological divergence, and eventually speciation.

In Chapter 2, a laboratory study tested the …

On Export Intermodal Transportation Problem, Supriya Arun Jadhav

Graduate Theses and Dissertations

This thesis investigates a logistics problem facing companies that export their products to other countries. The problem is called export intermodal transportation problem. In the export intermodal transportation problem, goods ordered by overseas customers need to be transported from production plants or warehouses of an export company to the customers destinations overseas. The transportation involves using multiple transportation modes such as trucks and rails for the inland portion and ocean liners for the overseas portion, and its objective is to have the goods moved and the cost minimized subject to various constraints. Cost can be minimized by combining orders from …

Community Structure And Ecological Specialization In Plant-Ant Interactions, Paola Barriga

Graduate Theses and Dissertations

Positive associations among species have contributed to the maintenance of biodiversity. These interactions are typically studied in pairwise fashion where two interacting organisms are the focus. This dissertation uses network theory to analyze positive plant-ant associations in three Neotropical forests. Obligate plant-ant mutualisms were used, where plants host the ants in domatia and provide food bodies while the ants protect the plants and can feed them. A network approach was used to depict all obligate plant-ant interactions within a community. The main questions asked at the community level were: 1) Do network structure and levels of specialization change geographically and, …

The Academic Effects Of Learning Styles On Esl (English As A Second Language) Students In Intensive English Language Centers, Baderaddin Mahmood Yassin

Graduate Theses and Dissertations

This study investigated the learning styles of ESL students (students who learn English as a second language). The focus in this study was on the ESL Arab Gulf (Saudi Arabia, Oman, Kuwait, and United Arab Emirates) students who study English as a second language in Intensive English Language Centers (IELCs) in the United States. The study explored the ESL Arab Gulf students' learning style preference and how they are affected by different variables such as cultural background, gender, and language level in IELCs. ESL Arab Gulf students were administered the VARK Learning Styles questionnaire. It measures several sensory types of …

Preparedness To Implement Wellness Strategies: Perceptions Of School Counselors, Tena Burnett

Graduate Theses and Dissertations

The purpose of this study is to survey school counselors to determine their knowledge and perceived preparedness to implement wellness strategies in school counseling programs. Wellness plans are a requirement for thousands of public school districts in the United States. There are no established standards for the training of school counselors in the area of wellness. School counselors are in a unique position to positively impact students through the use of wellness programs and strategies. School counselors from a mid-south state (N = 156) completed an electronic survey to measure how they implement wellness strategies and their perceived preparedness in …

Topics On Light-Emitting-Diode Driver Research, Jaber Hasan

Graduate Theses and Dissertations

In this dissertation, light-emitting-diode (LED) drivers are investigated for efficiency issues related to driving Red-Green-Blue (RGB) pixels and multiple LED strings in parallel. A high-efficiency digitally controlled RGB LED driver was designed for driving a 3x3 RGB LED display panel. A multiplexer was used to sense the voltage drop across the current controllers. This driver maintained a minimum drive voltage across the RGB LED pixels required to keep it in regulation leading to a reduction of unwanted power losses in the RGB LED pixels by selecting the minimum drop across the current-controllers as the reference voltage of the digital controller. …

Design Of A Pretreatment And Enzymatic Saccharification Scheme Of Understory From Managed Pine Forest For A Biochemical-Refinery Platform: The Example Of The Sweetgum Tree, Angele Djioleu

Graduate Theses and Dissertations

The possibility of using sweetgum from southern pine dominated forests as a biobased refinery feedstock was investigated. First, a baseline hydrolysis scheme for sweetgum wood and bark was designed. Sweetgum wood and bark were pretreated with 0.98% (v/v) sulfuric acid at 140°C for 30, 40, 50, 60 or 70 min and at 160°C for 30, 40, 50 or 60 min. The water insoluble solid (WIS) fraction was hydrolyzed with a cellulase enzyme cocktail. Results showed that maximum xylose and glucose yields from the wood were 82 and 86%, respectively. Similarly, the respective maximum yields of xylose and glucose from the …

On The Representation Of Inverse Semigroups By Difunctional Relations, Nathan Bloomfield

Graduate Theses and Dissertations

A semigroup S is called inverse if for each s in S, there exists a unique t in S such that sts = s and tst = t. A relation σ contained in X x Y is called full if for all x in X and y in Y there exist x' in X and y' in Y such that (x, y') and (x', y) are in σ, and is called difunctional if σ satisfies the equation σ σ^-1 σ = σ. Inverse semigroups were introduced by Wagner and Preston in 1952 and 1954, respectively, and difunctional relations were …

Effect Of Body Size And Exercise On Mood State, Alexandra Lachance

Graduate Theses and Dissertations

Exercising in the presence of nature (i.e., "green exercise"), has been shown to heighten the physiological and mental benefits of traditional exercise on non-obese individuals. The effects of green exercise on obese individuals are unknown. It is hypothesized that green exercise is more beneficial for obese (greater positive improvements in mental health scores), compared to non-obese individuals. For example, the benefits of green exercise could help lower feelings of depression, improve mood and self-esteem to increase the propensity of obese individuals to meet exercise recommendations. Accordingly, this study investigated the physiological and psychological effects of green exercise on 12 obese …

Stress-Adaptation And Stress-Induced Changes In Campylobacter Jejuni, Geetha Sanal Kumar-Phillips

Graduate Theses and Dissertations

The foodborne pathogen Campylobacter jejuni is one of the leading causes of human gastroenteritis. This bacterium is not a robust organism compared with many other foodborne pathogens and requires special conditions in the laboratory for its growth. In nature, however, this organism is able to survive in very diverse and hostile environments and produce disease in humans. The different mechanisms by which C. jejuni survives stressful conditions in the environment remain unclear. Adhesion and invasion are thought to be important factors for the colonization of C. jejuni in the intestinal tracts of hosts. Previous research in our laboratory showed that …

Energy And Spectral Efficient Wireless Communications, Guoqing Zhou

Graduate Theses and Dissertations

Energy and spectrum are two precious commodities for wireless communications. How to improve the energy and spectrum efficiency has become two critical issues for the designs of wireless communication systems. This dissertation is devoted to the development of energy and spectral efficient wireless communications. The developed techniques can be applied to a wide range of wireless communication systems, such as wireless sensor network (WSN) designed for structure health monitoring (SHM), medium access control (MAC) for multi-user systems, and cooperative spectrum sensing in cognitive radio systems.

First, to improve the energy efficiency in SHM WSN, a new ultra low power (ULP) …

Pre- And Post- Wage Differences Of Trade Adjustment Assistance Job Training Participants In Arkansas, Kimberley Hall Gordon

Graduate Theses and Dissertations

A number of costs are associated with the implementation of trade agreements not the least of which is the cost to the American workforce. The information age ushered in an era of globalization unlike anything the world economy had experienced before. As countries raced forward to dominate emerging markets and grow market share, millions of American workers were left in the wake. A remedy to the plight of the dislocated worker was found in trade adjustment assistance, specifically in job training benefits.

This study examined the wage differences experienced by Trade Adjustment Assistance (TAA) job training participants served through the …

What Is The Participant Learning Experience Like Using Youtube To Study A Foreign Language?, Yuan-Hsiang Lo

Graduate Theses and Dissertations

This research is to explore and understand participants' experience using YouTube to learn a foreign language. YouTube and learning has become more and more popular in the recent years. The finding of this research will be adding more understanding to the emerging body of knowledge of YouTube phenomenon. In this research, there are three interviews and two questionnaires. The interviews are conducted to find in-depth responses from participants; the questionnaires are used to inquire demographic and basic information about the participants. There are twelve themes found in this research. These themes reflect on the perceived experience using YouTube to learn …

Thermal And Electrical Parasitic Modeling For Multi-Chip Power Module Layout Synthesis, Zihao Gong

Graduate Theses and Dissertations

This thesis presents thermal and electrical parasitic modeling approaches for layout synthesis of Multi-Chip Power Modules (MCPMs). MCPMs integrate power semiconductor devices and drive electronics into a single package. As the switching frequency of power devices increases, the size of the passive components are greatly reduced leading to gains in efficiency and cost reduction. In order to increase switching frequency, electrical parasitics in MCPMs need to be reduced through tighter electronic integrations and smaller packages. As package size is decreased, temperature increases due to less heat dissipation capability. Thus, it is crucial to consider both thermal and electrical parasitics in …

The Development And Packaging Of A High-Density, Three-Phase, Silicon Carbide (Sic) Motor Drive, Jared Hornberger

Graduate Theses and Dissertations

Technology advances within the power electronics field are resulting in systems characterized by higher operating efficiencies, reduced footprint, minimal form factor, and decreasing mass. In particular, these attributes and characteristics are being inserted into numerous consumer applications, such as light-emitting diode lighting, compact fluorescent lighting, smart phones, and tablet PCs, to industrial applications that include hybrid, electric, and plug-in electric vehicles and more electric aircraft. To achieve the increase in energy efficiency and significant reduction in size and mass of these systems, power semiconductor device manufacturers are developing silicon carbide (SiC) semiconductor technology.

In this dissertation, the author discusses the …

The Biological Control Of Spotted Knapweed In The Southeastern United States, Carey R. Minteer

Graduate Theses and Dissertations

Spotted knapweed is an invasive, short-term-perennial plant that is native to Eurasia. It was accidentally introduced into North America in the early 1890's and has since spread across The United States and Canada. Spotted knapweed degrades rangelands and pastures by negatively impacting native plants, increasing soil surface runoff and stream sediment yields, and reducing soil infiltration. A biological control program for spotted knapweed using Larinus minutus (Coleoptera: Curculionidae), was initiated in Arkansas in 2008. In this dissertation I described the releases of L. minutus and investigated the adult activity in the southeastern United States (Chapter 1), investigated the effects of …

A Watershed Scale Evaluation Of Selected Second Generation Biofeedstocks On Water Quality, Gurdeep Singh

Graduate Theses and Dissertations

This study compares a novel simulation approach to the conventional Soil and Water Assessment Tool (SWAT) modeler's approach for targeting biofuel crop production on marginal lands. In conventional SWAT modeling approach, non-spatial definition of hydrological response units (HRUs) results in the simulation of biofuel crops on both marginal and non-marginal land. This study provides an alternative approach in which a marginal-land raster was integrated into the land use and land cover (LULC) raster in such a way that the land uses were divided into marginal and non-marginal components. This modified LULC was used for model setup which resulted in marginal …

Life History Variation Of Common Terns In The Gulf Of Maine, Jeffery Bryant Kimmons

Graduate Theses and Dissertations

Life history is the inheritable rules that determine energy and time allocation towards different competing functions in the energy budget of an organism. Reproductive effort varies as organisms make reproductive decisions based on available energy. Factors influencing life histories are those that change energy and time budgets such as diet, competition, and environmental conditions.

Common tern (Sterna hirundo) life history phenotypes vary between islands in the Gulf of Maine. Common terns on offshore islands (>10km from mainland) and nearshore islands (5 to 10km from mainland) lay smaller clutches, hatching chicks with slower growth rates than common terns …

Identifying Local Entrepreneurship Development System Policy In Rural Areas And How Local Context Shapes Entrepreneurship Policy Formation, Stacey Wright Mccullough

Graduate Theses and Dissertations

As rural communities struggle to maintain a sustainable economic base in today's global economy, many are exploring strategies to encourage entrepreneurial development. The purpose of this study was to better understand how local public policy is being be used to support the creation of entrepreneurship development systems in rural communities and how local context shapes entrepreneurship public policy formation. In phase one of the study, a survey and analysis of documents available on the Internet were used to identify county and municipal policy actions associated with entrepreneurial development in 16 counties in North Carolina. In the second study phase, two …

Effect Of Heat Treatments On The Properties Of Two Long-Grain Rice Cultivars During Storage, Youngbum Lee

Graduate Theses and Dissertations

During storage, the milling and physicochemical properties and eating quality of rice change, which is generally termed `aging'. Aged rice is preferred by processors, and there are attempts to develop accelerated aging process using various heat sources. In this study, the effects of various heat treatments and their influence on the milling, pasting, thermal, and cooking properties of two long-grain rice cultivars during storage were investigated using a full-factorial experimental design. Two long-grain rice cultivars, Wells and XP723, was treated with 8 different heat treatments including one control and stored at room temperature for 180 days. Heat treatments included 2 …

Analytical Research Topics In Sport Management, Gi-Yong Koo

Graduate Theses and Dissertations

The field of sport management has grown tremendously as an academic discipline. Researchers have continuously discussed the scope and direction of research and the importance of the diversity of research design. There have been a significant number of studies examining the scope and direction of research over the past few decades such as: the lack of diversity in methodology; the lack of diversity in research focus; the lack of importance of power analysis; and the lack of diversity in topic areas. Embracing a variety of research designs is an absolutely necessary condition for the growth and credibility of sport management …

New Applications Of Mass Spectrometry For Drug And Lipid Analysis, Elizabeth Lauren Emerson

Graduate Theses and Dissertations

Mass spectrometry is an important tool used in many different disciplines and settings that include forensics, drug discovery, environmental analysis, and proteomics. Gas chromatography - mass spectrometry (GC-MS) and matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI - TOF MS) are two of the most important instruments used for analysis of compounds. Chapters 1 and 2 of this discussion use GC-MS for the investigation of synthetic cannabinoids in `K2' incense products and the detection of metabolites in urine samples from individuals suspected of consuming these mixtures. Analytical standards were synthesized and used for identification and confirmation of structures. Detection of …