Physical Sciences and Mathematics Commons^™

Ambient Ionization - Mass Spectrometry: Advances Toward Intrasurgical Cancer Detection, Alan Keith Jarmusch

Open Access Dissertations

My dissertation research has focused on the development of ambient ionization – mass spectrometry (MS) for clinical measurements, specifically intrasurgical cancer detection. The molecular differences between normal and cancerous tissue were detected via direct tissue analysis in vitro by touch spray ionization (TS) or by analyzing sectioned or smeared tissue using desorption electrospray ionization (DESI). The physical form of the tissue, e.g. in vitro sampling, sectioned, or smeared, was inconsequential in differentiating normal from cancerous tissue; however, the spectra acquired by TS and DESI differed due to differences in ionization processes. We envision that TS-MS and DESI-MS could impact diagnostic …

Quantifying Terrestrial Ecosystem Carbon Dynamics With Mechanistically-Based Biogeochemistry Models And In Situ And Remotely Sensed Data, Shaoqing Liu

Open Access Dissertations

Terrestrial ecosystem plays a critical role in the global carbon cycle and climate system. Therefore, it is important to accurately quantify the carbon dynamics of terrestrial ecosystem under future climatic change condition. This dissertation evaluates the regional carbon dynamics by using upscaling approach, mechanistically-based biogeochemistry models and in situ and remotely sensed data.

The upscaling studies based on FLUXNET network has provided us the spatial and temporal pattern of the carbon fluxes but it fails to consider the atmospheric CO2 effect given its important physiological role in carbon assimilation. In the second chapter, we consider the effect of atmospheric CO2 …

Lower Food Web Dynamics In Lakes Michigan And Huron: Spatial And Temporal Responses To Recent Oligotrophication, Margaret Hutton Stadig

Open Access Theses

Nutrient abatement programs, originally enacted to counter eutrophication have successfully suppressed nutrient loads and relative primary production in marine and freshwater systems. Recently, the additive impacts of invasive filter feeders have further reduced offshore primary production in several aquatic systems throughout the world. It has been hypothesized that the biological activity of these invasive species may sequester nutrients within the nearshore benthic environment, creating steep gradients in primary production between nearshore and offshore habitats. In the Laurentian Great Lakes, past studies of oligotrophication have primarily focused on food web responses in offshore habitats. Organisms at higher trophic levels have been …

Mathematical Analysis Of Feedback Targets Of Bmp Signaling In Drosophila Embryonic Development, Yan Luo

Open Access Theses

Bone morphogenetic proteins (BMPs) drive a range of cellular processes especially in the early stages of embryonic development. This family of proteins acts as one of the most important extracellular signals in development pattern formation across the animal kingdom. Cells in embryos differentiate into different cell types in response to the concentration level of BMP. This complex process is regulated by multiple regulators that serve to tune the signal response.

Extensive experimental and computational research has been performed to analyze BMP regulation in Drosophila, a widely studied model organism, and has advanced our understanding of animal development. Because of …

Gonadal Intersex In Teleosts: Mechanisms, Molecular Biomarkers And Diagnostic Assays, Ahmed M.E. Abdel-Moneim Mohamed

Open Access Dissertations

Natural and synthetic estrogenic and androgenic compounds are continuously released into aquatic ecosystems. Exposure of teleost fishes to these contaminants can negatively impact sex differentiation and reproductive output. Specifically, development of gonadal intersex in gonochoristic (fixed sex) fish species has been studied extensively in relation to exposure to this class of compounds. The main objectives of this dissertation were to: 1) conduct field and laboratory studies to investigate the molecular signaling pathways behind the development of gonadal intersex; and 2) establish molecular biomarkers and assays for testing the ability of environmental pollutants to develop this condition using a battery of …

Unraveling The Fingerprints Of Nox Using Stable Isotopes: Implications For Nox Source Partitioning And Oxidation Chemistry, Wendell William Walters

Open Access Dissertations

The nitrogen (N) and oxygen (O) stable isotope composition (δ15N & δ18O) of nitrogen oxides (NOx )may be a useful tool for constraining NOx emission sources as well as for understanding the atmospheric oxidation pathways responsible for its removal if various NOx sources and sink processes exhibit characteristic isotopic compositions (“fingerprints”). However, this requires (1) an accurate and complete inventory of δ15N(NOx) values from major emission sources, (2) an assessment of the kinetic and equilibrium isotope effects that can impact δ15N and δ18O values of NOx, (3) and test these assumptions by conducting accurate in situ δ15N and δ18O measurements …

Willingness To Pay For Irrigation Water Under Scarcity Conditions, Tyler Robert Knapp

Graduate Theses and Dissertations

Reliance of Arkansas agricultural producers on groundwater for irrigation has led to depletion of the Mississippi River Valley alluvial aquifer. Without intervention, consequences include insufficient groundwater to meet irrigation demand as well as drawdown of the deeper Sparta Aquifer, upon which communities in eastern Arkansas rely for non-agricultural use. Among proposed solutions to combat groundwater decline is the construction of off-farm surface water infrastructure to meet the irrigation needs of producers. Despite the importance of irrigated agriculture to Arkansas, there is little know about the economic value of irrigation water to producers. Thus, we implement a double-bounded dichotomous choice contingent …

Gastrointestinal Health As A Stimulus For Native American Attraction To Medicinal Asteraceae And Further Implications For Human Evolution, Christopher David Stiegler

Graduate Theses and Dissertations

The Asteraceae, or the daisy family, is the largest family of flowering plants in the world, and its ethnobotanical, medical, and economic value is readily apparent cross-culturally. The aim of this thesis is to examine why constituent genera of the Aster family have remained such an integral part of human medicinal plant knowledge, and thereby to reveal any potential physiological, biological, or evolutionary mechanisms underlining human patterns of use regarding the Asteraceae. The present study focuses specifically on Native American plant knowledge made available by the expansive database in the works Daniel Moerman (Moerman 2003). Frequencies of plant use and …

Liming Characteristics Of A High-Calcium, Dry Flue Gas Desulfurization By-Product And Its Effects On Runoff Water Quality, Jason Richard Burgess-Conforti

Graduate Theses and Dissertations

In 2013, only 37% of the 32 million Mg of flue gas desulfurization (FGD) by-products generated in the United States were reused beneficially. If FGD by-products could be used as a beneficial soil amendment, millions of megagrams may be diverted away from surface impoundments and landfills. The purpose of this research was to identify the liming characteristics of a high-Ca dry FGD (DFGD) by-product in comparison to a Class-C fly ash (FA) and reagent-grade CaCO3, and to evaluate the effects of land application to a managed grassland on runoff, plant, and soil quality. Liming characteristics were determined by measuring the …

Intestinal Adaptation To Repeated Exposure Of Flavonoid-Rich Foods: In Vitro And Clinical Data, Bejamin W. Redan

Open Access Dissertations

Interest in application of flavonoids for chronic disease prevention has grown significantly, but the low oral bioavailability of these compounds from acute doses is commonly highlighted as a limitation when considering their biological significance. Still, the impact of broad dietary patterns such as repeated exposure on flavonoid’s absorption, metabolism, and eventual efficacy is critical to consider since evidence suggests that their bioavailability may be enhanced with repeated exposure. To fill this gap in knowledge, this dissertation will focus on three major areas including characterization of flavonoid metabolites, in addition to use of in vitro models and clinical work to test …

A Dose Distribution Study Of Uranyl Nitrate In Zebrafish Using Liquid Scintillation And Passivated Implanted Planar Silicon Detectors, Lee A. Alleman

Open Access Theses

Standard curves for a Perkin Elmer TriCarb 2800 liquid scintillation detector (LSC) and a Ludlum 3030p Passivated Implanted Planar Silicon detector have been developed and utilized for studying the dose distribution of depleted uranium (DU) within zebrafish. The DU source was crystallized uranyl nitrate (N2O8U•6H2O) solution, normally used for staining in electron microscopy with a manufactured average specific activity of 0.3 uCi/g. Zebrafish, both larvae and adults, were exposed to three different mass concentrations, dissected, dissolved and counted using an LSC. The counts were compared to the standard curve correlating the measured activity to that of the mass absorbed. It …

Manufacturer Perspectives On Content Transparency And Material Health In The Us Building Products Industry, Alexandra A. Muller

Open Access Theses

Flawed U.S. federal regulation of chemicals has resulted in a materials market that undervalues human and environmental health in favor of the more traditional attributes of price, performance and aesthetics. In the building products industry, global, dynamic supply chains and proprietary information concerns further complicate the task of assessing the material health of products.

Voluntary material health programs in the green building industry are intended to incentivize the manufacture and selection of safer products by getting companies to gather and assess ingredient, hazard and risk information from their supply chain. Building product manufacturers considered early adopters of the main material …

Nutrient Runoff And Leachate After Land-Application Of Digestate In A Laboratory Study Using Rainfall Simulations, Min Xiao

Open Access Theses

There has been an increasing number of anaerobic digesters on livestock farms in the United States during the past two decades. Anaerobic digestion of manure allows production of renewable energy and generation of stabilized and nutrient-rich digestate that can be used as organic fertilizer. However, the majority of the existed studies using liquid digestate as fertilizer only focused on the effectiveness for crop yield, nutrient content and microorganism in soil. There is insufficient understanding in the environmental impact of digestate land-application. This laboratory study used six treatments including four different liquid digestate treatments, a chemical fertilizer treatment, and an unfertilized …

South Padre Island Beach Management: Assessment Of Dune Restoration, Shelby Rose Bessette

Theses and Dissertations

Dune restoration is a common method of increasing coastal resilience. A dune restoration program was initiated by the City of South Padre Island, TX in 2010 consisting primarily of plantings of Sea Oats, Uniola paniculata, and Bitter Panicum, Panicum amarum and has continued approximately annually thereafter. These restoration efforts were evaluated in this study by comparing dune ecological structure and function among reference sites and restoration plots ranging in age from 2 to 5 years. Plant and animal communities were examined using a combination of quadrat sampling, funnel traps, pit-falls and sweep nets. Soil organic content and soil electric …

Analysis Of Artificial Neural Networks In The Diagnosing Of Breast Cancer Using Fine Needle Aspirates, Janette Vazquez

Theses and Dissertations

This thesis examines how Artificial Neural Networks can be used to classify a set of samples from a fine needle aspirate dataset. The dataset is composed of various different attributes, each of which are used to come to the conclusion as to whether a sample is benign or malignant. To automate the process of analyzing the various attributes and coming to a correct prediction, a neural network was implemented. First, a Feedforward Neural Network was trained with the dataset using a Backpropagation training method and an activation sigmoid function with one hidden layer in the architecture of the network. After …

Agro-Climatic Change, Crop Production And Mitigation Strategies-Case Studies In Arkansas, Usa And Kenya, John Westley Magugu

Graduate Theses and Dissertations

Although climate change impacts vary geographically and temporally, studies at local levels are not readily available for stakeholders to better understand how their local communities would be affected and what remedial measures could be more effective in their local contexts. This dissertation has examined climate change and its impacts in two different local contexts: eastern Arkansas in the USA and Nyando in Kenya. The first part of this dissertation develops agro-meteorological indicators and examines the relationship between agro-meteorological indicators and crop yields in eastern Arkansas between 1960 and 2014. Results reveal that temperature based indicators were more strongly correlated to …

Optical Water Quality And Human Perceptions Of Rivers, Amie West

Graduate Theses and Dissertations

Understanding water quality dynamics in recreational rivers is integral in shaping management strategies that maintain ecosystem health, perceived value and appeal, and regional economic significance in a changing environment. Optical water quality describes the behavior of light in water as governed by its physical and chemical composition, and is among the strongest influences on human perceptions of water quality. Ethnohydrology is the study of culturally constructed knowledge and understanding of water. This work is the culmination of an interdisciplinary approach to water resources research—integrating optical water quality and ethnohydrology methods to recognize the intersection between measured water quality and visible …

Electricity Generation, Electricity Consumption, And Energy Efficiency In The United States: A Dual Climatic-Behavioral Approach, Christopher A. Craig

Graduate Theses and Dissertations

Much of the United States (US) has seen an increase in warm days, decrease in cool days, and increase in extreme weather events. These trends are projected to continue across much of the US and in turn increase the demand for electricity and subsequent greenhouse gas emissions. Ambitious energy efficiency (EE) programs are used across the US by energy utility organizations to reduce electricity demand and emissions. This study examined the impact of climatic variability on electricity consumption, as well as how pro-conservation interventions such as EE programs and experiential learning can be utilized to mitigate residential electricity consumption and …

Trend Analysis Of Water Quality In Northwest Arkansas Streams Reflects Changes In The Watershed, Zachary Paul Simpson

Graduate Theses and Dissertations

Watershed export of nutrients, sediments, and chemicals impacts receiving waters. Changes within the watershed (e.g., anthropogenic or climatic) can alter the transport of constituents in streams. Stream monitoring is crucial for understanding these effects. This study developed a potential improvement to flow-adjusting constituent concentrations in streams, an important step of analyzing monitoring data in lotic systems for trends. The method incorporates a K-fold cross-validation procedure to optimize a model explaining the relationship between the concentration and streamflow, thus providing a valuable tool to researchers in water quality. Additionally, two case studies were conducted on watersheds located in northwest Arkansas using …

Eucalyptus In Kenya; Impacts On Environment And Society, Brandy M. Garrett Kluthe

Graduate Theses and Dissertations

Eucalyptus trees were introduced to Kenya a little over a century ago. European colonization along with the development of a railway system increased the demand for a fast growing wood source. The expansion of the tree across the fertile lands in Kenya raises concerns about the environmental impact on ecosystems where it has been introduced. These concerns include degraded soils, loss of water resources, co-introduction of ectomycorrhizal species, and allelopathy. Economic benefits to local landowners were also explored as well as the potential for large Eucalyptus woodlots to maximize the sequestration of CO₂ from the atmosphere. This was examined through …

Evaluating A Measure-Calculate Method For Determining Sediment Oxygen Demand In Lakes, Adrian Beirise

Graduate Theses and Dissertations

A steady-state mass diffusion model used with simple measurable and calculable inputs for determining sediment oxygen demand (SOD) is compared to an intact core incubation (ICI) SOD method using samples from three lakes. The mass diffusion model coupled with inputs is known as the measure-calculate method (M-C) and is a potential alternative to existing methods for measuring SOD which are more complex, time-consuming, and costly. The M-C method requires inputs for volumetric sediment oxygen uptake (Ṅsed), sediment density and porosity, and water properties. Ṅsed was determined by suspending sediment in oxygen-saturated water with a DO probe and determining the steady …

The Role Of Organic Matter In The Fate And Transport Of Antibiotic Resistance, Metals, And Nutrients In The Karst Of Northwest Arkansas, Victor Lee Roland Ii

Graduate Theses and Dissertations

Organic matter (OM) in the environment acts as a nutrient, but may also act as a transport vector for harmful chemical compounds and bacteria. Acetate is a labile form of OM produced during fermentation in anaerobic lagoons used to store animal fecal-waste from concentrated animal feeding operations (CAFOs). Dry and liquid fertilizers from CAFOs pose a threat to groundwater by introducing excessive amounts of nutrients (e.g. OM, nitrate and ammonia), metals, and antibiotic compounds. In the epikarst of Northern Arkansas in the Buffalo River watershed additional input of labile dissolved organic carbon (DOC) from liquid CAFO waste-fertilizers was hypothesized to …

Risk Estimation Toward A Natural History Model For Low Grade Glioma Patients, Anh Thi Hoang Pham

Graduate Theses and Dissertations

Glioma is a common type of primary brain tumor that represents 28% of all brain tumors and 80% of malignant tumors. According to a recent study by the Centers for Disease Control and Prevention (CDC), gliomas account for 53%, 35% and 29% of all brain tumors (68%, 74% and 81% of malignant brain tumors) among children (aged 0-14), teenagers (aged 15-19) and young adults, respectively. Gliomas are often diagnosed through radiological imaging and histopathology. There are two main groups of gliomas following World Health Organization’s classification: Low grade gliomas (LGG), or grade I and II gliomas; and high grade gliomas …

A Method Comparison And Stressor-Response Experimental Study Of Nitrogen And Phosphorus Impacts To Periphyton In Ozark Streams, Ashley Renee Rodman

Graduate Theses and Dissertations

Stream bioassessment is important for understanding algal-nutrient relationships and the development of scientifically defensible numeric nutrient criteria. However, multiple methods of periphyton data collection are currently used, and little is known about the comparability of resulting datasets. Literature also suggests other factors besides nutrients (i.e. variable grazing, light, and flow) can confound algal-nutrient relationships. A one-year method comparison study and 31-day algal biomass-nutrient manipulative experiment were conducted in the southern Ozarks of Arkansas. The method comparison study was implemented using two common bioassessment procedures (whole-surface and delimiter-reduced periphyton removal) to assess the potential for combining datasets. During the manipulative experiment, …

Evaluation Of Rusle 2 To Estimate Soil Loss From Pastures, Stasha Katrina Balkissoon

Graduate Theses and Dissertations

The accurate estimation of soil erosion by the Revised Universal Soil Loss Equation version 2 (RUSLE2) is critical for several conservation assessments, least of which is its use in the Phosphorus Index (PI) to identify and rank the vulnerability of agricultural fields to phosphorus (P) runoff. Earlier versions of RUSLE reported a soil loss overestimation, which were revised to give RUSLE2, where biomass production in different climatic regions was more accurately represented. RUSLE version 2.0, which contains the new vegetative biomass production routine, was evaluated using two performance indices, the Nash Sutcliffe Efficiency Index (NSE) and Index of Agreement (D) …

Dissemination And Persistence Of Plasmid Located, Integron Associated Antibiotic Resistant Genes In Wastewater Treatment Plant Effluent And Stream Water Bacteria, _ Suhartono

Graduate Theses and Dissertations

Transmissible plasmid-mediated integrons play important role in the persistence and dissemination of antibiotic resistance throughout the environment. Plasmids from 139 multi-antibiotic resistant Escherichia coli recovered from wastewater treatment plant effluent and upstream and downstream receiving stream water in Northwest Arkansas were extracted and profiled. Genes of class 1 and class 2 integrase (intI), mobilization (mob), sulfamethoxazole resistance (sul), and trimethoprim resistance (dfr) were detected using PCR and confirmed through DNA sequencing. Plasmids from almost half of the isolates (47%) were transmissible with mobF12 gene as the most frequently detected mobilization gene. Plasmid-borne class 1 with and without class 2 integrons …

Behavioral Responses And Policy Evaluation: Revisiting Water And Fuel Policies, Shanxia Sun

Open Access Dissertations

In my dissertation, I examine how policies regulating agricultural production and clean technology impact the environment. I focus on policies affecting water depletion, water pollution, and fuel consumption. I assess their cost-effectiveness by modeling and quantifying the behavioral responses of farmers and households.

My first essay focuses on decreasing groundwater depletion through increasing irrigation efficiency in Mexico. I quantify the impacts of different sources of inefficiency on groundwater extraction, and I evaluate the effectiveness of alternative policies that aim to reduce the over-extraction of groundwater. I find that mechanisms of electricity cost-sharing implemented in many wells have a sizable impact …

Economic And Environmental Impacts Of A Hypothetical Global Gmo Ban, Harrison H. Mahaffey

Open Access Theses

The objective of this research is to assess the global economic and greenhouse gas emission impacts of GMO crops. This is done by modeling two counterfactual scenarios and evaluating them apart and in combination. The first scenario models the impact of a global GMO ban. The second scenario models the impact of increased GMO penetration. The focus is on the price and welfare impacts, and land use change greenhouse gas (GHG) emissions associated with GMO technologies. Much of the prior work on the economic impacts of GMO technology has relied on a combination of partial equilibrium analysis and econometric techniques. …

Investigating U.S. Resident Perceptions Of Corporate Social Responsibility In Food And Agriculture, Carissa Jae Morgan

Open Access Theses

Corporations are prioritizing corporate social responsibility (CSR) activities by investing in and actively promoting their social practices. In the U.S. of the modern food supply chain creates a unique challenge for corporations to address concerns about social issues of consumers and non-consumers alike. This study is motivated by the need to better understand individuals’ perceptions of CSR as it pertains to the food supply chain. In April 2015 an online survey collected information from 1,201 U.S. residents with the objective of investigating individuals’ perceptions of relative importance of eight prominent CSR areas relevant to food and agriculture. Demographic, household consumption, …

Quantifying The Global N2o Emissions From Natural Ecosystems Using A Mechanistically-Based Biogeochemistry Model, Tong Yu

Open Access Theses

Nitrous oxide (N2O) has a great influence on atmospheric chemistry and climate. It is not only a major greenhouse gas, but also one of the largest ozone-depleting substances emitted from the biosphere. Process-based biogeochemistry modeling constrained by site-level observations is a feasible approach to quantifying its emissions at large temporal and spatial scales. This study developed a process-based biogeochemistry model of N2O emissions based on an extant biogeochemistry model, the Terrestrial Ecosystem Model (TEM). The model development includes: 1) incorporating the effects of physical conditions on both nitrification and denitrification and 2) implementing principles of the stoichiometry of carbon and …