Digital Commons Network^™

Atomic Level Characterization For The Transport Cycle Conformational Pathways Of Multidrug Resistance Protein 1 (Mrp1), Samuel Wamwere Mwatha

Graduate Theses and Dissertations

The multidrug resistance-associated protein 1 (MRP1/ABCC1) is an ATP-binding cassette (ABC) transporter that mediates the cellular efflux of endogenous and xenobiotic substrates, including therapeutic drugs. Its overexpression is a major contributor to multidrug resistance in cancer, which tends to result in negative clinical results. Even with considerable progress made in structural biology, the intricate details of how membrane lipid composition affects the conformational changes and functional switches of MRP1 still lack explanation.

This thesis employs long-timescale, all-atom molecular dynamics (MD) simulations to study the influence of various lipids on MRP1 lipid bilayer environments. Both inward-facing and outward-facing conformations of MRP1 …

Rotation Errors Due To Field Quantization For Simultaneously Driven Atoms, Hunter Lindemann

Graduate Theses and Dissertations

If we want to physically implement qubits by using two level atoms within a cavity, then certain single-qubit gates (such as the X-gate) can be performed by bathing the atoms in an electromagnetic field from a laser. If the average photon count n̄ of the field greatly exceeds the number of N qubits, then the slight fluctuations of the field's phase and amplitude are mostly negligible. However, such a strong field might require more energy than what is desirable for the setup. If a weaker field is used in which phase and amplitude fluctuations might be noticeable, then the …

Exploring The Relationship Between Novice Teacher Autonomy And Workplace Engagement, Burnout, And Intentions To Remain In The Teaching Profession, Bryce Bennett

Graduate Theses and Dissertations

Administrators and experienced faculty frequently disagree on the degree of autonomy that should exist for classroom teachers. Administrators seeking to make adjustments to the levels of autonomy experienced by their teachers may struggle to account for differences between novice teachers and their more seasoned counterparts. This study applies researched-based models for exploring the relationship between various job resources and demands and their ultimate impact on workers. A mixed method designed employing a survey across three large school districts in Arkansas asked participants questions intended to uncover the degree of autonomy novice teachers typically experience, levels of burnout & workplace engagement, …

Real-Time Anomaly Detection In Ot Networks Using Gru-Based Autoencoders, Grant Austin Wilkins

Graduate Theses and Dissertations

Operational Technology (OT) networks, particularly those used in critical infrastructure, face increasing cyber threats that target network-level protocols and behaviors. While most anomaly detection research for OT systems has traditionally relied on sensor data, this thesis explores the viability of detecting malicious activity directly from network telemetry. We propose a sequence-to-sequence autoencoder model based on Gated Recurrent Units (GRUs) with multilevel attention, trained to reconstruct normal patterns of packet-level communication extracted from raw PCAP data. The developed feature engineering pipeline integrates general networking attributes such as IP and MAC addresses, ports, and transport protocols with OT-specific protocol information from Modbus …

A Robust Rf Fingerprinting Approach Using Physics-Informed Neural Networks, Jozef Dusenka

Graduate Theses and Dissertations

Radio frequency (RF) fingerprints, caused by unique imperfections in communication hardware, offer a promising solution for zero-trust security. However, existing RF fingerprinting techniques, which aim to extract these signatures from transmitters to uniquely identify devices, often struggle with robustness in the face of temporal and spatial variations in real-world, time-varying wireless environments. For example, a neural network trained on RF signals collected on Day 1 can experience a significant performance drop when tested with data from Day 2.

To address this challenge, we propose a novel, robust RF fingerprinting method based on Physics-Informed Neural Networks (PINNs). Rather than training the …

Exploring Non-Traditional Yeast For Flavor Innovation In Non-Alcoholic Beer, Andrew Maust, Rahul Sen, Scott Lafontaine

Food Science Faculty Publications and Presentations

The demand for nonalcoholic beer (NAB) is growing, with nontraditional yeast strains emerging as valuable tools for brewers to craft distinct NABs. However, independent information about the performance of these commercially available yeasts remains limited. In this study, 11 nontraditional yeast strains were evaluated at two wort nutrient levels to assess their impact on beer chemistry, sensory attributes, and volatile profiles. Basic fermentation metrics were monitored, followed by descriptive sensory analysis and GC-MS/MS quantification of volatile compounds. Results revealed significant differentiation among yeast strains with unique aroma and flavor profiles driven by variations in ester production, fusel alcohol synthesis, and …

The Formation Of Glacier Dirt Cones, Ryan M. Strickland, Matthew D. Covington

Geosciences Faculty Publications and Presentations

Glacier dirt cones are meter-scale cones of ice covered with sediment and rock. The cones develop through a process known as differential melt, whereby ice underlying thick debris melts more slowly than bare ice. We report observations of dirt cones on the Kuskulana Glacier, Alaska and develop a model that simulates the growth of dirt cones from debris-filled pits in the ice. With this model, we vary ice melt rates, hillslope debris diffusion rates and pit geometry. Cone heights scale with the square root of debris volume and growth occurs in three distinct stages: emergence, flux-controlled growth and melt-controlled growth. …

A Non-Linear Optimization Model For Controlling The Real Area Of Contact In Surface Texture Design, Sandra Eksioglu, Min Zou

Industrial Engineering Faculty Publications and Presentations

Motivated by the potential of surface texturing to enhance the tribological performance of micro- and nano-electromechanical systems (MEMS/NEMS), this study proposes a novel non-linear optimization approach for designing textured surfaces. This model minimizes the contact area between interacting surfaces and deformation during sliding under dry conditions by controlling key design parameters, such as the size and shape of the designed surface. We test the performance of the proposed model using the lotus leaf surface with dimensions of 248 x 136 micrometers. Due to the large size of the model, we propose a solution approach which consists of a data aggregation …

Transient Thermal Energy Harvesting At A Single Temperature Using Nonlinearity, Tamzeed B. Amin, James M. Mangum, Md R. Kabir, Syed M. Rahman, Pradeep Ashaduzzaman, Pradeep Kumar, Luis L. Bonilla, Paul M. Thibado

Physics Faculty Publications and Presentations

The authors present an in-depth theoretical study of two nonlinear circuits capable of transient thermal energy harvesting at one temperature. The first circuit has a storage capacitor and diode connected in series. The second circuit has three storage capacitors, and two diodes arranged for full wave rectification. The authors solve both Ito-Langevin and Fokker-Planck equations for both circuits using a large parameter space including capacitance values and diode quality. Surprisingly, using diodes one can harvest thermal energy at a single temperature by charging capacitors. However, this is a transient phenomenon. In equilibrium, the capacitor charge is zero, and this solution …

A Tutorial For Scanning Electrochemical Cell Microscopy (Seccm) Measurements: Step-By-Step Instructions, Visual Resources, And Guidance For First Experiments, Kamsy Lerae Anderson, Martin Andrew Edwards

Chemistry & Biochemistry Faculty Publications and Presentations

Scanning electrochemical cell microscopy (SECCM) produces nanoscale-resolution electrochemical maps of electrode surfaces using the meniscus at the tip of an electrolyte-filled nanopipette as a mobile electrochemical cell. While the use and range of applications of SECCM have grown rapidly since its introduction, the pathway to performing SECCM measurements can be daunting to those without direct access to expert users. This work fills this expertise gap by providing a step-by-step guide to performing one's first SECCM experiments, including troubleshooting strategies, videos/images, suggested parameters and experimental systems, and representative data (of both successful experiments and common problems). No background in SECCM is …

The Mechanistic Target Of Rapamycin Mediates Clostridium Perfringens-Induced Chicken Necrotic Enteritis Attenuated By Secondary Bile Acid Deoxycholic Acid, Mohit Bansal, Tahrir Alenezi, Ying Fu, Janashrit Shrestha, Ayidh Almansour, Hong Wang, Anamika Gupta, Rohana Liyanage, Xiaolun Sun

Poultry Science Faculty Publications and Presentations

Clostridium perfringens is a prevalent gut bacterial pathogen in humans and animals. This study investigated the role of the mechanistic targets of rapamycin (mTOR) and deoxycholic acid (DCA) on C. perfringens intestinal infection. Chickens were sequentially infected with Eimeria maxima and received the mTOR inhibitor rapamycin and DCA. C. perfringens-induced necrotic enteritis (NE) was evaluated using body weight gain (BWG), histopathology, bile acids, pathogen colonization, cell infiltration and death, and gene expression. The significant difference of p < 0.05 was analyzed by one-way ANOVA and multiple comparisons. Notably, rapamycin strongly reduced the subclinical and clinical NE histopathologies. DCA and DCA combined with rapamycin alleviated clinical NE and BWG loss. Rapamycin, DCA, and DCA + rapamycin attenuated bile acid reduction in NE birds, and they also reduced immune cell infiltration into the intestinal lamina propria as well as immune cell migration in vitro. At molecular levels, DCA and DCA + rapamycin reduced proinflammatory IFN gamma, MMP9, IL23, and IL17 gene expression. Rapamycin, DCA, and DCA + rapamycin reduced NE-induced intestinal cell apoptosis. Together, these results suggest that mTOR signaling mediates C. perfringens-induced ileitis, and combining mTOR inhibition and DCA improves the intervention efficacy against NE ileitis and BWG loss.

Enhancing Tree Species Mapping In Arkansas’ Forests Through Machine Learning And Satellite Data Fusion: A Google Earth Engine–Based Approach, Abdullah Al Saim, Mohamed Aly

Geosciences Faculty Publications and Presentations

Arkansas' subtropical climate nurtures extensive forested regions, particularly within the Ozark-St. Francis and Ouachita National Forests. Despite this, the state lacks an up-to-date high-resolution map detailing the distribution of tree species within its forests. This study harnesses the power of machine learning, specifically the Random Forest (RF), Gradient Tree Boosting (GTB), Support Vector Machine (SVM), and K-Nearest Neighbors (K-NN) classifiers, within the Google Earth Engine (GEE) framework. These classifiers are applied to classify tree species distribution in Arkansas' forests by integrating data from various sources, including Sentinel-1/-2, Landsat-8, and the National Agriculture Imagery Program (NAIP). The study evaluates the classification …

Overexpression And Biophysical And Functional Characterization Of A Recombinant Fgf21, Phuc Phan, Jason Hoang, Thallapuranam Krishnaswamy Suresh Kumar

Chemistry & Biochemistry Faculty Publications and Presentations

Fibroblast growth factor 21 (FGF21) is an endocrine FGF that plays a vital role in regulating essential metabolic pathways. FGF21 increases glucose uptake by cells, promotes fatty acid oxidation, reduces blood glucose levels, and alleviates metabolic diseases. However, detailed studies on its stability and biophysical characteristics have not been reported. Herein, we present the overexpression, biophysical characterization, and metabolic activity of a soluble recombinant FGF21 (rFGF21). The far-UV circular dichroism spectra of rFGF21 show a negative trough at 215 nm, indicating that the protein's backbone predominantly adopts a 13 sheet conformation. rFGF21 shows intrinsic tyrosine fluorescence at 305 nm. Thermal …

Conformational Free Energy Landscape Of A Glutamate Transporter And Microscopic Details Of Its Transport Mechanism, Sundar Thangapandian, Ashkan Fakharzadeh, Mahmoud Moradi, Emad Tajkhorshid

Chemistry & Biochemistry Faculty Publications and Presentations

Removing glutamate from the synaptic cleft is vital for proper function of the brain. Excitatory amino acid transporters mediate this process by uptaking the neurotransmitter from the synaptic cleft back to the cell after its release. The archaeal homolog, GltPh, an aspartate transporter from Pyrococcus horikoshii, presents the best structurally characterized model for this family of transporters. In order to transport, GltPh undergoes elevator-like conformational changes between inward-facing (IF) and outward-facing (OF) states. Here, we characterize, at an atomic level, the OF=+/- IF transition of GltPh in different apo/bound states using a combination of ensemble-based enhanced sampling techniques, employing more …

Wayne E. Sabbe Arkansas Soil Fertility Studies 2024, Nathan A. Slaton

Arkansas Agricultural Experiment Station Research Series

Rapid technological changes in crop management and production require that the research efforts be presented in an expeditious manner. The contributions of soil fertility and fertilizers are major production factors in all Arkansas crops. The studies described within will allow producers to compare their practices with the university’s research efforts. Additionally, soil-test data and fertilizer sales are presented to allow comparisons among years, crops, and other areas within Arkansas.

Widening The Net: How Cogat And Act Aspire Compare In Gifted Identification, Al Mansor Helal, Jonathan Wai, Andy Parra-Martinez, Sarah Mckenzie, Dustin Seaton

Education Reform Faculty and Graduate Students Publications

Previous research indicates that many academically accomplished students from disadvantaged backgrounds are not identified for gifted and talented (G/T) programs. This study examines a large sample of students (N = 10,508), many of whom took both the Cognitive Abilities Test (CogAT) and the ACT Aspire test. We examined test similarities and differences with an eye to widen the net for G/T identification in practice. This study demonstrates that the ACT Aspire and CogAT have a significant correlation in our sample of r = .59. However, the correlation varies across cohorts noticeably from r = .72 to r = .49. This …

The Learning Crisis In The United States Three Years After Covid-19, Harry Anthony Patrinos, Maciej Jakubowski, Tomasz Gajderowicz

Education Reform Faculty and Graduate Students Publications

The COVID-19 pandemic caused widespread disruptions to education, with school closures affecting over one billion children. These closures, aimed at reducing virus transmission, resulted in significant learning losses, particularly in mathematics and science. Using United States data from TIMSS, this study analyzes the impact of school closure on learning outcomes. The losses amount to 0.36 SD for mathematics and 0.16 SD for science. The declines are similar across grades. The average decline in mathematics performance among U.S. students is substantially greater than the global average. n science, the decline observed among U.S. students does not significantly differ from the global …

Sobolev Regularity For The Bergman Projection On Relatively Compact Domains In Hermitian Manifolds, Philip Harrington

Mathematical Sciences Faculty Publications and Presentations

Generalizing a result of Berndtsson and Charpentier, we provide sufficient conditions for L2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$L< ^>2$$\end{document} Sobolev regularity of the Bergman projection acting on L2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$L< ^>2$$\end{document} sections of a holomorphic line bundle restricted to a relatively compact domain with Lipschitz boundary in a Hermitian manifold. We provide examples to show that our methods work for domains in Hopf manifolds endowed with a suitable Hermitian metric.

Low-Level Kinetic-Energy-Powered Temperature Sensing System, James M. Mangum, Syed M. Rahman, Tamzeed B. Amin, Md R. Kabir, Hung Do, Gordon Carichner, David Blaauw, Paul M. Thibado

Physics Faculty Publications and Presentations

Powering modern nanowatt sensors from omnipresent low-level kinetic energy: This study investigates the power levels produced by a varying-capacitance kinetic energy harvesting system. A model system consisting of a uniformly driven rotating capacitor was built to develop an accurate output power performance model. We found a quantitative linear relationship between the rectified output current and the input applied bias voltage, driving frequency, and capacitance variation. We also demonstrate that our variable capacitor system is equivalent to a fixed capacitor driven with an alternating current power source. Both the fixed-capacitance and varying-capacitance energy harvesting systems recharge a three-volt battery, which in …

Characterizing The Stability Of Ultra-Thin Metal Oxide Catalyst Films In Non-Thermal Plasma Co2 Reduction Reactions, Samuel Keith Conlin, Joseph Joel Muhanga, David Parette, Robert H. Coridan

Chemistry & Biochemistry Faculty Publications and Presentations

The use of metal oxide catalysts to enhance plasma CO2 reduction has seen significant recent development towards processes to reduce greenhouse gas emissions and produce renewable chemical feedstocks. While plasma reactors are effective at producing the intended chemical transformations, the conditions can result in catalyst degradation. Atomic layer deposition (ALD) can be used to synthesize complex, hierarchically structured metal oxide plasma catalysts that, while active for plasma CO2 reduction, are potentially vulnerable to degradation due to their high surface area and nanoscopic thickness. In this work, we characterized the effects of extended non-thermal, glow discharge plasma exposure on ALD synthesized, …

Active Learning-Based Automated Construction Of Hamiltonian For Structural Phase Transitions: A Case Study On Batio3, Mian Dai, Yixuan Zhang, Nuno Fortunato, Peng Chen, Hongbin Zhang

Physics Faculty Publications and Presentations

The effective Hamiltonians have been widely applied to simulate the phase transitions inpolarizable materials, with coefficients obtained by fitting to accurate first-principlescalculations. However, it is tedious to generate distorted structures with symmetry constraints,in particular when high-ordered terms are considered. In this work, we implement and apply aBayesian optimization-based approach to sample potential energy surfaces, automating theeffective Hamiltonian construction by selecting distorted structures via active learning. Taking BaTiO3(BTO) as an example, we demonstrate that the effective Hamiltonian can be obtainedusing fewer than 30 distorted structures. Follow-up Monte Carlo simulations can reproduce thestructural phase transition temperatures of BTO, comparable to experimental values …

The Effects Of Functional Moves In Teacher Questioning On Students’ Contextualization Of Mathematical Word Problem Solving, Yi-Jung Lee

Curriculum and Instruction Faculty Publications and Presentations

Posing purposeful questions is one of the most effective teaching practices (NCTM in Principles to actions: Ensuring mathematics success for all. National Council of Teachers of Mathematics, 2014). Although the types and functions of teacher questioning have been abundantly studied, research on the role of teacher questioning in students’ contextualization process as they solve word problems is rather scarce. This study was conducted to investigate the function of six elementary preservice teachers’ questioning, its impact on students’ contextualization, as well as the successes and difficulties of enacting questioning. The collected data were analyzed using thematic analysis. The findings indicated that …

An All-Hazards Return On Investment (Roi) Model To Evaluate Us Army Installation Resilient Strategies, Gregory S. Parnell, Robert Curry, Eric Specking, Anthony Beger, Randy Buchanan, Susan Wolters, John P. Richards, Patrick R. Ables

Industrial Engineering Faculty Publications and Presentations

The paper describes our project to develop, verify, and deploy an All-Hazards Return of Investment (ROI) model for the U. S. Army Engineer Research and Development Center (ERDC) to provide army installations with a decision support tool for evaluating strategies to make existing installation facilities more resilient. The need for increased resilience to extreme weather caused by climate change was required by U.S. code and DoD guidance, as well as an army strategic plan that stipulated an ROI model to evaluate relevant resilient strategies. During the project, the ERDC integrated the University of Arkansas designed model into a new army …

Photogalvanic Shift Currents In Bifeo3-Lafeo3 Superlattices, Francesco Delodovici, Charles Paillard

Physics Faculty Publications and Presentations

Designing materials with a controlled photovoltaic response may lead to improved solar cells or photosensors. In this regard, ferroelectric superlattices have emerged as a rich platform to engineer functional properties. In addition, ferroelectrics are naturally endowed with a bulk photovoltaic response stemming from nonthermalized photoexcited carriers, which can overcome the fundamental limits of current solar cells. Yet, their photovoltaic output has been limited by poor optical absorption and poor charge collection or photoexcited carrier mean free path. We use Density Functional Theory and Wannierization to compute the so-called Bulk Photovoltaic shift current and the optical properties of BiFeO3/LaFeO3 superlattices. We …

Large Negative Magnetoresistance In The Off-Stoichiometric Topological Semimetal Prsbxte2-X, Gokul Acharya, Krishna Pandey, M. M. Sharma, Jian Wang, Santosh Karki Chhetri, Md Rafique Un Nabi, Dinesh Upreti, Rabindra Basnet, Joshua Sakon, Jin Hu

Physics Faculty Publications and Presentations

Magnetic topological materials LnSbTe (Ln = lanthanide) have attracted intensive attention because of the presence of interplay between magnetism, topological, and electron correlations depending on the choices of magnetic Ln elements. Varying Sb and Te composition is an efficient approach to control structural, magnetic, and electronic properties. Here, we report on the composition-dependent properties in PrSbxTe2-x. We identified the tetragonal-to-orthorhombic structure transitions in this material system and very large negative magnetoresistance in the x = 0.3 composition, which might be ascribed to the coupling between magnetism and transport. Such unusual magnetotransport enables PrSbxTe2-x topological materials as a promising platform for …

The Fathers Have Eaten Sour Grapes: History Is The Wrong Test For Establishment Clause Questions In Public Schools, Abigail Riddle

Arkansas Law Review

The old quip goes, “As long as there are math tests, students will pray in the schools.” There is, however, a distinction between private and public prayers; the former allows religious students to find peace and comfort in a moment of anxiety, and the latter openly divides the religious majority from the religious and nonreligious minority, ostracizing the minority and exacerbating their nerves. This Note examines the constitutionality of religious exercises initiated by public school faculty and staff at public education’s founding, arguing that the special considerations present when considering prayer in these contexts are too important to be limited …

An Ultra-Low-Power 0.8 V, 60 Nw Temperature Sensor For Battery-Less Wireless Sensor Networks, Fnu Naveed, Jeff Dix

Electrical Engineering and Computer Science Faculty Publications and Presentations

This work presents a nano-watt digital output temperature sensor featuring a supply-insensitive, self-biased current source. Second-order temperature dependencies of the MOS diode are canceled to produce a stable reference and a linear temperature-sensitive voltage. The sensor integrates a sensing unit, voltage-controlled differential ring oscillators, and a low-power frequency-to-digital converter, utilizing a resistor-less design to minimize power and area. The delay element in the ring oscillator reduces stage count, improving noise performance and compactness. Fabricated in 65 nm CMOS, the sensor occupies 0.02 mm2 and consumes 60 nW at 25 °C and 0.8 V. Measurements show an inaccuracy of +1.5/−1.6 °C …

Bridging Taste And Health: The Role Of Machine Learning In Consumer Food Selection, Saroj Adhikari, Brandon R. Mcfadden

Agricultural Economics and Agribusiness Faculty Publications and Presentations

Navigating the modern food landscape is complex, often leading consumers to make suboptimal dietary choices due to information, time constraints, and psychological vulnerabilities. Machine learning (ML) presents a promising solution to enhance the contemporary grocery shopping experience by providing personalized dietary recommendations tailored to individual preferences and characteristics. Traditional methods of dietary guidance cannot account for nuanced consumer characteristics and preferences. In contrast, ML algorithms can incorporate specific information about individuals and continuously adapt to provide personalized recommendations, considering factors like historical eating habits, socio-demographics, nutritional requirements, etc. This paper explores the potential value of ML in enhancing personalized dietary …

Undergraduate Catalog Of Studies, University Of Arkansas, Fayetteville

Undergraduate Catalog of Studies

No abstract provided.

Budget For The Fiscal Year Ending June 30, 2025, University Of Arkansas, Fayetteville

Budget for the Fiscal Year

No abstract provided.