Digital Commons Network^™

Noninvasive Measurement Of Electrical Events Associated With A Single Chlorovirus Infection Of A Microalgal Cell, Seung-Woo Lee, Eun-Hee Lee, Gerhard Thiel, James L. Van Etten, Ravi Saraf

Department of Chemical and Biomolecular Engineering: Faculty Publications

Chlorovirus Paramecium bursaria chlorella virus 1 (PBCV-1) contains a viral-encoded K⁺ channel imbedded in its internal membrane, which triggers host plasma membrane depolarization during virus infection. This early stage of infection was monitored at high resolution by recording the cell membrane depolarization of a single Chlorella cell during infection by a single PBCV-1 particle. The measurement was achieved by depositing the cells onto a network of one-dimensional necklaces of Au nanoparticles, which spanned two electrodes 70 μm apart. The nanoparticle necklace array has been shown to behave as a single-electron device at room temperature. The resulting electrochemical field-effect transistor …

The Metal/Organic Interface In Cobalt/Vinylidene Fluoride Heterostructures, Keith Foreman, E Echeverria, Mark A. Koten, R. M. Lindsay, N. Hong, Jeffrey E. Shield, Shireen Adenwalla

Shireen Adenwalla Papers

Organic-based electronic devices are rapidly increasing in popularity, making it essential to understand and characterize the interface between organic materials and metallic electrodes. This work reports on the characterization of the interface between thin films of an emerging organic ferroelectric, vinylidene fluoride (VDF) oligomer, and Co, an important high Curie temperature ferromagnet. Using a wide battery of experimental techniques, it is shown that VDF oligomer thin films as thin as 15 nm can halt, or prevent, Co oxidization in atmospheric conditions, a necessary condition for device applications. Selectivity of magnetic properties, such as remanent magnetization, is enabled by the clarification …

Ferroelectric Characterization And Growth Optimization Of Thermally Evaporated Vinylidene Fluoride Thin Films, Keith Foreman, N. Hong, C. Labedz, C. Shearer, Stephen Ducharme, Shireen Adenwalla

Shireen Adenwalla Papers

Organic thin films have numerous advantages over inorganics in device processing and price. The large polarization of the organic ferroelectric oligomer vinylidene fluoride (VDF) could prove useful for both device applications and the investigation of fundamental physical phenomena. A VDF oligomer thin film vacuum deposition process, such as thermal evaporation, preserves film and interface cleanliness, but is challenging, with successful deposition occurring only within a narrow parameter space. We report on the optimal deposition parameters for VDF oligomer thin films, refining the parameter space for successful deposition, resulting in a high yield of robust ferroelectric films. In particular, we investigate …

Magnetic And Magneto-Transport Studies Of Substrate Effect On The Martensitic Transformation In A Nimnin Shape Memory Alloy, Andrei Sokolov, Eugene Kirianov, Albina Zlenko, Abdiel Quetz, Anil Aryal, Sudip Pandey, Igor Dubenko, Shane Stadler, Naushad Ali, Nabil M. Al-Aqtash, Renat F. Sabirianov

Department of Physics and Astronomy: Faculty Publications

The effect of substrates on the magnetic and transport properties of Ni₂Mn_1.5In_0.5 ultra-thin films were studied theoretically and experimentally. High quality 8-nm films were grown by laser-assisted molecular beam epitaxy deposition. Magnetotransport measurements revealed that the films undergo electronic structure transformation similar to those of bulk materials at the martensitic transformation. The temperature of the transformation depends strongly on lattice parameters of the substrate. To explain this behavior, we performed DFT calculations on the system and found that different substrates change the relative stability of the ferromagnetic (FM) austenite and ferrimagnetic (FiM) martensite states. We …

Stability Of Skyrmion Lattices And Symmetries Of Quasi-Two-Dimensional Chiral Magnets, Utkan Güngördü, Rabindra Nepal, Oleg A. Tretiakov, Kirill D. Belashchenko, Alexey Kovalev

Department of Physics and Astronomy: Faculty Publications

Recently there has been substantial interest in realizations of skyrmions, in particular in quasi-two-dimensional (2D) systems due to increased stability resulting from reduced dimensionality. A stable skyrmion, representing the smallest realizable magnetic texture, could be an ideal element for ultradense magnetic memories. Here we use the most general form of the quasi-2D free energy with Dzyaloshinskii-Moriya interactions constructed from general symmetry considerations reflecting the underlying system. We predict that the skyrmion phase is robust and it is present even when the system lacks the in-plane rotational symmetry. In fact, the lowered symmetry leads to increased stability of vortex-antivortex lattices with …

Magnetoelectric Domain Wall Dynamics And Its Implications For Magnetoelectric Memory, Kirill D. Belashchenko, Oleg Tchernyshyov, Alexey Kovalev, Oleg A. Tretiakov

Department of Physics and Astronomy: Faculty Publications

Domain wall dynamics in a magnetoelectric antiferromagnet is analyzed, and its implications for magnetoelectric memory applications are discussed. Cr₂O₃ is used in the estimates of the materials parameters. It is found that the domain wall mobility has a maximum as a function of the electric field due to the gyrotropic coupling induced by it. In Cr₂O₃, the maximal mobility of 0.1 m/(s Oe) is reached at E = 0.06 V/nm. Fields of this order may be too weak to overcome the intrinsic depinning field, which is estimated for B-doped Cr₂O_{3 …}

Electron Acceleration And Generation Of High-Brilliance X-Ray Radiation In Kilojoule, Subpicosecond Laser-Plasma Interactions, J. Ferri, X. Davoine, S. Y. Kalmykov, A. Lifschitz

Department of Physics and Astronomy: Faculty Publications

Petawatt, picosecond laser pulses offer rich opportunities in generating synchrotron x-rays. This paper concentrates on the regimes accessible with the PETAL laser, which is a part of the Laser Megajoule (LMJ) facility. We explore two physically distinct scenarios through Particle-in-Cell simulations. The first one realizes in a dense plasma, such that the period of electron Langmuir oscillations is much shorter than the pulse duration. Hallmarks of this regime are longitudinal breakup (“self-modulation”) of the picosecond-scale laser pulse and excitation of a rapidly evolving broken plasma wake. It is found that electron beams with a charge of several tens of nCcan …

Immunotherapy Using Algal-Produced Ara H 1 Core Domain Suppresses Peanut Allergy In Mice, James A. Grgeory, Ariel Shepley-Mctaggart, Michelle Umpierrez, Barry K. Hurlburt, Soheila J. Maleki, Hugh A. Sampson, Stephen P. Mayfield, M. Cecilia Berin

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Peanut allergy is an IgE-mediated adverse reaction to a subset of proteins found in peanuts. Immunotherapy aims to desensitize allergic patients through repeated and escalating exposures for several months to years using extracts or flours. The complex mix of proteins and variability between preparations complicates immunotherapy studies. Moreover, peanut immunotherapy is associated with frequent negative side effects and patients are often at risk of allergic reactions once immunotherapy is discontinued. Allergen-specific approaches using recombinant proteins are an attractive alternative because they allow more precise dosing and the opportunity to engineer proteins with improved safety profiles. We tested whether Ara h …

An Aircraft Evacuation Simulation Baseline Using Des For Passenger Path Planning, Xiaoqing Deng

Doctoral Dissertations and Master's Theses

This paper introduced a Discrete Event Simulation (DES) model that simulates passengers’ evacuation paths and decision-making processes during aircraft certification. The model was built using ARENA® 14, which is a DES simulation tool. This model used A380 cabin configuration with capacity of 538 passengers. Each passenger was considered as an independent human being with variations in walking speed, decision-making processes, and evacuation path. This model generated total evacuation time and presented total congestion conditions of each gate. Federal Regulation has suggested that all passengers in the airplane should finish the evacuation within 90 seconds. The model was validated with the …

Sliding Mode Observers For Distributed Parameter Systems: Theory And Applications, Niloofar Nasiri Kamran

Doctoral Dissertations and Master's Theses

Many processes in nature and industry can be described by partial differential equations. PDEs employ quantities such as density, temperature, velocity, etc. and their partial derivatives to model these phenomena. However, in the case of distributed parameter systems, it is not always possible to have access to the states of the systems due to technical difficulties such as lack of sensors. Therefore, there is the need for state observers to estimate the states of the system only having the output of the system available. In this research, the theory of sliding mode and variable structure systems are employed in order …

A Biomimetic, Energy-Harvesting, Obstacle-Avoiding, Path-Planning Algorithm For Uavs, Snorri Gudmundsson

Doctoral Dissertations and Master's Theses

This dissertation presents two new approaches to energy harvesting for Unmanned Aerial Vehicles (UAV). One method is based on the Potential Flow Method (PFM); the other method seeds a wind-field map based on updraft peak analysis and then applies a variant of the Bellman-Ford algorithm to find the minimum-cost path. Both methods are enhanced by taking into account the performance characteristics of the aircraft using advanced performance theory. The combined approach yields five possible trajectories from which the one with the minimum energy cost is selected. The dissertation concludes by using the developed theory and modeling tools to simulate the …

Modeling Shattercane Dynamics In Herbicide-Tolerant Grain Sorghum Cropping Systems, Rodrigo Werle, Brigitte Tenhumberg, John L. Lindquist

Department of Agronomy and Horticulture: Faculty Publications

Traditional breeding technology is currently being used to develop grain sorghum [Sorghum bicolor (L.) Moench ssp. bicolor] germplasm that will be tolerant to acetolactate synthase (ALS)-inhibiting herbicides. This technology (Inzen^TM, DuPont^TM) has the potential to improve sorghum production by allowing for the postemergence control of traditionally hard-to-control grasses. However, grain sorghum and shattercane [weedy Sorghum species; Sorghum bicolor (L.) Moench ssp. drummondii (Nees ex Steud.) de Wet ex Davidse] can interbreed and introduced traits such as herbicide tolerance could increase the weediness of the weedy relative. Our objective was to develop a simulation model …

Dioxygenase-Encoding Atdao1 Gene Controls Iaa Oxidation And Homeostasis In Arabidopsis, Silvana Porco, Aleš Pěnčík, Afaf Rashed, Ute Voβ, Rubén Casanova-Sáez, Anthony Bishop, Agata Golebiowska, Rahul Bhosale, Ranjan Swarup, Kamal Swarup, Pavlína Penáková, Ondrej Novák, Paul E. Staswick, Peter Hedden, Andrew L. Phillips, Kris Vissenberg, Malcolm J. Bennett, Karin Ljung

Department of Agronomy and Horticulture: Faculty Publications

Auxin represents a key signal in plants, regulating almost every aspect of their growth and development. Major breakthroughs have been made dissecting the molecular basis of auxin transport, perception, and response. In contrast, how plants control the metabolism and homeostasis of the major form of auxin in plants, indole-3- acetic acid (IAA), remains unclear. In this paper, we initially describe the function of the Arabidopsis thaliana gene DIOXYGENASE FOR AUXIN OXIDATION 1 (AtDAO1). Transcriptional and translational reporter lines revealed that AtDAO1 encodes a highly root-expressed, cytoplasmically localized IAA oxidase. Stable isotope-labeled IAA feeding studies of loss and …

The Draft Genome Of The C3 Panicoid Grass Species Dichanthelium Oligosanthes, Anthony J. Studer, James C. Schnable, Sarit Weissmann, Allison R. Kolbe, Michael R. Mckain, Ying Shao, Asaph B. Cousins, Elizabeth A. Kellogg, Thomas P. Brutnell

Department of Agronomy and Horticulture: Faculty Publications

Background: Comparisons between C₃ and C₄ grasses often utilize C₃ species from the subfamilies Ehrhartoideae or Pooideae and C₄ species from the subfamily Panicoideae, two clades that diverged over 50 million years ago. The divergence of the C₃ panicoid grass Dichanthelium oligosanthes from the independent C₄ lineages represented by Setaria viridis and Sorghum bicolor occurred approximately 15 million years ago, which is significantly more recent than members of the Bambusoideae, Ehrhartoideae, and Pooideae subfamilies. D. oligosanthes is ideally placed within the panicoid clade for comparative studies of C₃ and C₄ grasses.

Results: …

Yield Gap Analysis Of Us Rice Production Systems Shows Opportunities For Improvement, Matthew B. Espe, Kenneth Cassman, Haishun Yang, Nicolas Guilpart, Patricio Grassini, Justin Van Wart, Merle Anders, Donn Beighley, Dustin Harrell, Steve Linscombe, Kent Mckenzie, Randall Mutters, Lloyd T. Wilson, Bruce A. Linquist

Department of Agronomy and Horticulture: Faculty Publications

Many assessments of crop yield gaps based on comparisons to actual yields suggest grain yields in highly intensified agricultural systems are at or near the maximum yield attainable. However, these estimates can be biased in situations where yields are below full yield potential. Rice yields in the US continue to increase annually, suggesting that rice yields are not near the potential. In the interest of directing future efforts towards areas where improvement is most easily achieved, we estimated yield potential and yield gaps in US rice production systems, which are amongst the highest yielding rice systems globally. Zones around fourteen …

Smokey Comes Of Age: Unmanned Aerial Systems For Fire Management, Dirac L. Twidwell Jr., Craig R. Allen, Carrick Detweiler, James Higgins, Christian Laney, Sebastian Elbaum

Department of Agronomy and Horticulture: Faculty Publications

During the past century, fire management has focused on techniques both to protect human communities from catastrophic wildfire and to maintain fire-dependent ecological systems. However, despite a large and increasing allocation of resources and personnel to achieve these goals, fire management objectives at regional to global scales are not being met. Current fire management techniques are clearly inadequate for the challenges faced by fire managers, and technological innovations are needed. Advances in unmanned aerial systems (UAS) technology provide opportunities for innovation in fire management and science. In many countries, fire management organizations are beginning to explore the potential of UAS …

A Spatial-Dynamical Framework For Evaluation Of Satellite Rainfall Products For Flood Prediction, Felipe Quintero, Witold F. Krajewski, Ricardo Mantilla, Scott Small, Bong Chul Seo

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Rainfall maps that are derived from satellite observations provide hydrologists with an unprecedented opportunity to forecast floods globally. However, the limitation of using these precipitation estimates with respect to producing reliable flood forecasts at multiple scales are not well understood. To address the scientific and practical question of applicability of space-based rainfall products for global flood forecasting, a data evaluation framework is developed that allows tracking the rainfall effects in space and time across scales in the river network. This provides insights on the effects of rainfall product resolution and uncertainty. Obtaining such insights is not possible when the hydrologic …

Deployment And Performance Analyses Of High-Resolution Iowa Xpol Radar System During The Nasa Ifloods Campaign, Kumar Vijay Mishra, Witold F. Krajewski, Radoslaw Goska, Daniel Ceynar, Bong Chul Seo, Anton Kruger, James J. Niemeier, Miguel B. Galvez, Merhala Thurai, V. N. Bringi, Leonid Tolstoy, Paul A. Kucera, Walter A. Petersen, Jacopo Grazioli

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This article presents the data collected and analyzed using the University of Iowa's X-band polarimetric (XPOL) radars that were part of the spring 2013 hydrology-oriented Iowa Flood Studies (IFloodS) field campaign, sponsored by NASA's Global Precipitation Measurement (GPM) Ground Validation (GV) program. The four mobile radars have full scanning capabilities that provide quantitative estimation of the rainfall at high temporal and spatial resolutions over experimental watersheds. IFloodS was the first extensive test of the XPOL radars, and the XPOL radars demonstrated their field worthiness during this campaign with 46 days of nearly uninterrupted, remotely monitored, and controlled operations. This paper …

Impact Of Pre-Anthesis Water Deficit On Yield And Yield Components In Barley (Hordeum Vulgare L.) Plants Grown Under Controlled Conditions, Zakaria I. Al-Ajlouni, Ayed Al-Abdallat, Abdul Latief A. Al-Ghzawi, Jamal Y. Ayad, Jamal M. Abu Elenein, Nisreen A. Al-Quraan, P. Stephen Baenziger

Department of Agronomy and Horticulture: Faculty Publications

Drought at pre-anthesis stages can influence barley growth and results in yield losses. Therefore, it is important to understand how drought at pre-anthesis can affect different traits associated with yield reduction in barley. The objective of this study was to understand the relevance of the genetic background of major flowering time genes in barley plants subjected to pre-anthesis drought and its impact on yield and yield components. A glasshouse experiment using a Randomized Complete Block Design was conducted to investigate the effect of drought and its timing on yield and yield components on eleven barley genotypes, which were selected to …

The C-Terminal Motif Of Siago1b Is Required For The Regulation Of Growth, Development And Stress Responses In Foxtail Millet (Setaria Italica (L.) P. Beauv), Xiaotong Liu, Sha Tang, Guanqing Jia, James C. Schnable, Haixia Su, Chanjuan Tang, Hui Zhi, Xianmin Diao

Department of Agronomy and Horticulture: Faculty Publications

Foxtail millet (Setaria italica (L.) P. Beauv), which belongs to the Panicoideae tribe of the Poaceae, is an important grain crop widely grown in Northern China and India. It is currently developing into a novel model species for functional genomics of the Panicoideae as a result of its fully available reference genome sequence, small diploid genome (2n=18, ~510 Mb), short life cycle, small stature and prolific seed production. Argonaute 1 (AGO1), belonging to the argonaute (AGO) protein family, recruits small RNAs and regulates plant growth and development. Here, we characterized an AGO1 mutant (siago1b) in foxtail millet, which …

Expression Of Apoplast-Targeted Plant Defensin Mtdef4.2 Confers Resistance To Leaf Rust Pathogen Puccinia Triticina But Does Not Affect Mycorrhizal Symbiosis In Transgenic Wheat, Jagdeep Kaur, John Fellers, Alok Adholeya, Siva L.S. Velivelli, Kaoutar El-Mounadi, Natalya Nersesian, Thomas Clemente, Dilip Shah

Department of Agronomy and Horticulture: Faculty Publications

Rust fungi of the order Pucciniales are destructive pathogens of wheat worldwide. Leaf rust caused by the obligate, biotrophic basidiomycete fungus Puccinia triticina (Pt) is an economically important disease capable of causing up to 50 % yield losses. Historically, resistant wheat cultivars have been used to control leaf rust, but genetic resistance is ephemeral and breaks down with the emergence of new virulent Pt races. There is a need to develop alternative measures for control of leaf rust in wheat. Development of transgenic wheat expressing an antifungal defensin offers a promising approach to complement the endogenous resistance genes …

Corn (Zea Mays L.) Seeding Rate Optimization In Iowa, Usa, Mark A. Licht, Andrew W. Lenssen, Roger W. Elmore

Department of Agronomy and Horticulture: Faculty Publications

Collecting soil, topography, and yield information has become more feasible and reliable with advancements in precision technologies. Combined with the accessibility of precision technologies and services to farmers, there has been increased interest and ability to make site-specific crop management decisions. The objective of this research was to develop procedures to optimize corn seeding rates and maximize yield using soil and topographic parameters. Experimental treatments included five seeding rates (61 750; 74 100; 86 450; 98 800; and 111 150 seeds ha^-1) in a randomized complete block design in three central Iowa fields from 2012 to 2014 (nine …

Properties Of Self-Compacting Concrete With Recycled Coarse Aggregate, W. C. Tang, P. C. Ryan, H. Z. Cui, W. Liao

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The utilization of recycled concrete aggregate (RCA) in Self-Compacting Concrete (SCC) has the potential to reduce both the environmental impact and financial cost associated with this increasingly popular concrete type. However, to date limited research exists exploring the use of coarse RCA in SCC. The work presented in this paper seeks to build on the existing knowledge in this area by examining the workability, strength, and fracture properties of SCCs containing 0%, 25%, 50%, 75%, and 100% coarse RCA. The experimental programme indicated that at RCA utilization levels of 25% to 50% little or no negative impact was observed for …

Digital Badges For Stem Learning In Secondary Contexts: A Mixed Methods Study, Angela Elkordy

Master's Theses and Doctoral Dissertations

The deficit in STEM skills is a matter of concern for national economies and a major focus for educational policy makers. The development of Information and Communications Technologies (ICT) has resulted in a rapidly changing workforce of global scale. In addition, ICT have fostered the growth of digital and mobile technologies which have been the learning context, formal and informal, for a generation of youth. The purpose of this study was to design an intervention based upon a competency-based, digitally-mediated, learning intervention: digital badges for learning STEM habits of mind and practices. Designed purposefully, digital badge learning trajectories and criteria …

The Vaccine And The Virus: An Autoethnographic Account Of Hpv, Sex Education, And The Psychosocial Effects Of Sti's, Jamie L. Morgan

Master's Theses and Doctoral Dissertations

In 2006 the Food and Drug Administration (FDA) approved the Gardasil vaccine to assist in the protection from the Human Papillomavirus (HPV): The leading contributor to cervical cancer. After stressing the importance of the vaccine, but disregarding its inadequacies, young women were subjected to invasive and excessive protocols. This study utilizes autoethnographic methods to understand the psychological and social effects of the individuals who were diagnosed with HPV before the release of the Gardasil 9 vaccine in 2014 and forced to go through these unnecessary procedures before the medical field began adopting imperative changes to treatment.

Effects Of Emotional Intelligence On Academic Achievement In The Alternative High School Classroom, Rhonda L. Marcum-Phillips

Master's Theses and Doctoral Dissertations

This study examines the impact of emotional intelligence, academic self-efficacy in science and technology, and family background on academic achievement of alternative high school students. Gender, age, learning style, and ethnicity of the student are analyzed to determine any moderator effect on these relationships. Seventy-five students, ages 14 to19, who attend a public alternative high school were surveyed. Analysis of the data revealed a positive relationship for males between self-efficacy in STEM classes and family background (support) and their academic achievement in science class. A positive relationship was shown between self-efficacy in STEM classes and academic achievement, between self-efficacy in …

Construction Of An Optical Fiber Strian Gauge, Najwa Sulaiman

Master's Theses and Doctoral Dissertations

This project is focused on the construction of an optical fiber strain gauge that is based on a strain gauge described by Butter and Hocker. Our gauge is designed to generate an interference pattern from the signals carried on two bare single-mode fibers that are fastened to an aluminum cantilever. When the cantilever experiences flexural stress, the interference pattern should change. By observing this change, it is possible to determine the strain experienced by the cantilever. I describe the design and construction of our optical fiber strain gauge as well as the characterization of different parts of the apparatus.

Mapping Citizenship: Status, Membership, And The Path In Between, D. Carolina Nuñez

Faculty Scholarship

No abstract provided.

Increasing Off-Chip Bandwidth And Mitigating Dark Silicon Via Switchable Pins, Shaoming Chen

LSU Doctoral Dissertations

Off-chip memory bandwidth has been considered as one of the major limiting factors to processor performance, especially for multi-cores and many-cores. Conventional processor design allocates a large portion of off-chip pins to deliver power, leaving a small number of pins for processor signal communication. We observed that the processor requires much less power than that can be supplied during memory intensive stages in some cases. In this work, we propose a dynamic pin switch technique to alleviate the bandwidth limitation issue. The technique is introduced to dynamically exploit the surplus pins for power delivery in the memory intensive phases and …

Full State Revivals In Linearly Coupled Chains With Commensurate Eigenspectra, J. J. P. Veerman, Jovan Petrovic

Mathematics and Statistics Faculty Publications and Presentations

Coherent state transfer is an important requirement in the construction of quantum computer hardware. The state transfer can be realized by linear next-neighbour-coupled finite chains. Starting from the commensurability of chain eigenvalues as the general condition of periodic dynamics, we find chains that support full periodic state revivals. For short chains, exact solutions are found analytically by solving the inverse eigenvalue problem to obtain the coupling coefficients between chain elements. We apply the solutions to design optical waveguide arrays and perform numerical simulations of light propagation thorough realistic waveguide structures. Applications of the presented method to the realization of a …