Physical Sciences and Mathematics Commons^™

Globe-Lfmc, A Global Plant Water Status Database For Vegetation Ecophysiology And Wildfire Applications, Marta Yebra, Gianluca Scortechini, Abdulbaset Badi, Maria Eugenia Beget, Matthias M. Boer, Ross Bradstock, Emilio Chuvieco, F. Mark Danson, Philip Dennison, Victor Resco De Dios, Carlos M. Di Bella, Greg Forsyth, Philip Frost, Mariano Garcia, Abdelaziz Hamdi, Binbin He, Matt Jolly, Tineke Kraaij, M. Pilar Martín, Florent Mouillot, Glenn Newnham, Rachael H. Nolan, Grazia Pellizzaro, Yi Qi, Xingwen Quan, David Riaño, Dar Roberts, Momadou Sow, Susan Ustin

School of Natural Resources: Faculty Publications

Globe-LFMC is an extensive global database of live fuel moisture content (LFMC) measured from 1,383 sampling sites in 11 countries: Argentina, Australia, China, France, Italy, Senegal, Spain, South Africa, Tunisia, United Kingdom and the United States of America. The database contains 161,717 individual records based on in situ destructive samples used to measure LFMC, representing the amount of water in plant leaves per unit of dry matter. The primary goal of the database is to calibrate and validate remote sensing algorithms used to predict LFMC. However, this database is also relevant for the calibration and validation of dynamic global vegetation …

Evolutionary History Predicts High‐Impact Invasions By Herbivorous Insects, Angela M. Mech, Kathryn A. Thomas, Travis D. Marsico, Daniel A. Herms, Craig R. Allen, Matthew P. Ayres, Kamal J.K. Gandhi, Jessica Gurevitch, Nathan P. Havill, Ruth A. Hufbauer, Andrew M. Liebhold, Kenneth F. Raffa, Ashley N. Schulz, Daniel R. Uden, Patrick C. Tobin

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

1. A long‐standing goal of invasion biology is to identify factors driving highly variable impacts of non‐native species. Although hypotheses exist that emphasize the role of evolutionary history (e.g., enemy release hypothesis & defense‐free space hypothesis), predicting the impact of non‐native herbivorous insects has eluded scientists for over a century.

2. Using a census of all 58 non‐native conifer‐specialist insects in North America, we quantified the contribution of over 25 factors that could affect the impact they have on their novel hosts, including insect traits (fecundity, voltinism, native range, etc.), host traits (shade tolerance, growth rate, wood density, etc.), and …

Magnetoelectric Effect At The Ni/Hfo2 Interface Induced By Ferroelectric Polarization, Qiong Yang, Lingling Tao, Zhen Jiang, Yichun Zhou, Evgeny Tsymbal, Vitaly Alexandrov

Evgeny Tsymbal Publications

Driven by the technological importance of the recently discovered ferroelectric HfO₂, we explore a magnetoelectric effect at the HfO₂-based ferroelectric-ferromagnetic interface. Using density-functionaltheory calculations of the Ni/HfO₂/Ni (001) heterostructure as a model system, we predict a stable and sizable ferroelectric polarization in a few-nm-thick HfO₂ layer. For the Ni/HfO₂ interface with opposite polarization directions (pointing to or away from the interface), we find a sizable difference in the interfacial Ni—O bonding, resulting in dissimilar degrees of depletion of the electron density around the interface. The latter affects the relative population of the …

Comparison Of The Efficacy Of Four Drug Combinations For Immobilization Of Wild Pigs, Christine K. Ellis, Morgan E. Wehtje, Lisa L. Wolfe, Peregrine L. Wolff, Clayton D. Hilton, Mark C. Fisher, Shari Green, Michael P. Glow, Joeseph M. Halseth, Michael J. Lavelle, Nathan P. Snow, Eric H. Vannatta, Jack C. Rhyan, Kurt C. Vercauteren, William R. Lance, Pauline Nol

United States Department of Agriculture Wildlife Services: Staff Publications

Field immobilization of native or invasive wild pigs (Sus scrofa) is challenging. Drug combinations commonly used often result in unsatisfactory immobilization, poor recovery, and adverse side effects, leading to unsafe handling conditions for both animals and humans. We compared four chemical immobilization combinations, medetomidine–midazolam–butorphanol (MMB), butorphanol–azaperone–medetomidine (BAM™), nalbuphine–medetomidine–azaperone (NalMed-A), and tiletamine– zolazepam–xylazine (TZX), to determine which drug combinations might provide better chemical immobilization of wild pigs. We achieved adequate immobilization with no post-recovery morbidity withMMB. Adequate immobilization was achieved with BAM™; however, we observed post-recovery morbidity. Both MMB and BAM™ produced more optimal results relative to body temperature, recovery, and …

Systematic Optimization For Production Of The Anti-Mrsa Antibiotics Wap-8294a In An Engineered Strain Of Lysobacter Enzymogenes, Xusheng Chen, Shanren Li, Lingjun Yu, Amanda Miller, Liangcheng Du

Chemistry Department: Faculty Publications

WAP-8294A is a group of cyclic lipodepsipeptides and considered as the first-in-class new chemical entity with potent activity against methicillin-resistant Staphylococcus aureus. One of the roadblocks in developing the WAP-8294A antibiotics is the very low yield in Lysobacter. Here, we carried out a systematic investigation of the nutritional and environmental conditions in an engineered L. enzymogenes strain for the optimal production of WAP-8294A. We developed an activity-based simple method for quick screening of various factors, which enabled us to optimize the culture conditions. With the method, we were able to improve the WAP-8294A yield by 10-fold in small-scale cultures and …

Vision In An Abundant North American Bird: The Red-Winged Blackbird, Esteban Fernández-Juricic, Patrice E. Baumhardt, Luke P. Tyrrell, Amanda Elmore, Shelagh T. Deliberto, Scott J. Werner

United States Department of Agriculture Wildlife Services: Staff Publications

Avian vision is fundamentally different from human vision; however, even within birds there are substantial between species differences in visual perception in terms of visual acuity, visual coverage, and color vision. However, there are not many species that have all these visual traits described, which can constrain our ability to study the evolution of visual systems in birds. To start addressing this gap, we characterized multiple traits of the visual system (visual coverage, visual acuity, centers of acute vision, and color vision) of the Red-winged Blackbird (Agelaius phoeniceus), one of the most abundant and studied birds in North America. We …

Social Interactions Do Not Drive Territory Aggregation In A Grassland Songbird, S.K. Winnicki, S.M. Munguia, E.J. Williams, W.A. Boyle

United States National Park Service: Publications

Understanding the drivers of animal distributions is a fundamental goal of ecology and informs habitat management. The costs and benefits of colonial aggregations in animals are well established, but the factors leading to aggregation in territorial animals remain unclear. Territorial animals might aggregate to facilitate social behavior such as (1) group defense from predators and/or parasites, (2) cooperative care of offspring, (3) extra-pair mating, and/or (4) mitigating costs of extra-pair mating through kin selection. Using experimental and observational methods, we tested predictions of all four hypotheses in a tallgrass prairie in northeast Kansas, United States. Grasshopper Sparrow (Ammodramus savannarum) males …

Roadmap On Photonic, Electronic And Atomic Collision Physics: Ii. Electron And Antimatter Interactions, Stefan Schippers, Emma Sokell, Friedrich Aumayr, Hossein Sadeghpour, Kiyoshi Ueda, Igor Bray, Klaus Bartschat, Andrew Murray, Jonathan Tennyson, Alexander Dorn, Masakazu Yamazaki, Masahiko Takahashi, Nigel Mason, Oldřich Novotný, Andreas Wolf, Leon Sanche, Martin Centurion, Yasunori Yamazaki, Gaetana Laricchia, Clifford M. Surko, James Sullivan, Gleb Gribakin, Daniel Wolf Savin, Yuri Ralchenko, Ronnie Hoekstra, Gerry O'Sullivan

Martin Centurion Publications

We publish three Roadmaps on photonic, electronic and atomic collision physics in order to celebrate the 60th anniversary of the ICPEAC conference. In Roadmap II we focus on electron and antimatter interactions. Modern theoretical and experimental approaches provide detailed insight into the many body quantum dynamics of leptonic collisions with targets of varying complexity ranging from neutral and charged atoms to large biomolecules and clusters. These developments have been driven by technological progress and by the needs of adjacent areas of science such as astrophysics, plasma physics and radiation biophysics. This Roadmap aims at looking back along the road, explaining …

Low Secondary Risks For Captive Coyotes From A Sodium Nitrite Toxic Bait For Invasive Wild Pigs, Nathan P. Snow, Katherine E. Horak, Simon T. Humphrys, Linton D. Staples, David G. Hewitt, Kurt C. Vercauteren

United States Department of Agriculture Wildlife Services: Staff Publications

An acute toxic bait is being developed to deliver micro‐encapsulated sodium nitrite (SN) to stimulate severe methemoglobinemia and humane death for invasive wild pigs (Sus scrofa), thereby providing a new tool for reducing their populations. During April 2016, we evaluated sensitivity to SN and outcomes of secondary consumption in the ubiquitous mammalian scavenger, coyote (Canis latrans), to determine secondary risks of consuming carcasses of wild pigs that died from consuming the SN toxic bait. At the National Wildlife Research Center in Fort Collins, Colorado, USA, we first evaluated whether coyotes fed carcasses of domestic pigs killed by consumption of SN …

Calibration And Validation Of The Cosmic Ray Neutron Rover For Soilwater Mapping Within Two South African Land Classes, Thigesh Vather, Colin Everson, Trenton E. Franz

School of Natural Resources: Faculty Publications

Knowledge of soil water at a range of spatial scales would further our understanding of the dynamic variable and its influence on numerous hydrological applications. Cosmic ray neutron technology currently consists of the Cosmic Ray Neutron Sensor (CRNS) and the Cosmic Ray Neutron Rover (CRNR). The CRNR is an innovative tool to map surface soil water across the land surface. This research assessed the calibration and validation of the CRNR at two survey sites (hygrophilous grassland and pine forest) within the Vasi area with an area of 72 and 56 ha, respectively. The assessment of the calibrations showed that consistent …

Modeling Irrigation Behavior In Groundwater Systems, Timothy Foster, Nicholas Brozovic, Adrian P. Butler

Daugherty Water for Food Global Institute: Faculty Publications

Integrated hydro-economic models have been widely applied to water management problems in regions of intensive groundwater-fed irrigation. However, policy interpretations may be limited as most existing models do not explicitly consider two important aspects of observed irrigation decision making, namely the limits on instantaneous irrigation rates imposed by well yield and the intraseasonal structure of irrigation planning. We develop a new modeling approach for determining irrigation demand that is based on observed farmer behavior and captures the impacts on production and water use of both well yield and climate. Through a case study of irrigated corn production in the Texas …

Water Productivity In Meat And Milk Production In The Us From 1960 To 2016, Mesfin Mekonnen, C.M.U. Neale, Chittaranjan Ray, Galen E. Erickson, Arjen Y. Hoekstra

Daugherty Water for Food Global Institute: Faculty Publications

Global demand for livestock products is rising, resulting in a growing demand for feed and potentially burdening freshwater resources to produce this feed. To offset this increased pressure on water resources, the environmental performance of livestock sector should continue to improve. Over the last few decades, product output per animal and feedstuff yields in the US have improved, but before now it was unclear to what extent these improvements influenced the water productivity (WP) of the livestock products. In this research, we estimate changes in WP of animal products from 1960 to 2016. We consider feed conversion ratios (dry matter …

Diffractive Imaging Of Dissociation And Ground-State Dynamics In A Complex Molecule, Kyle J. Wilkin, Robert M. Parrish, Jie Yang, Thomas J.A. Wolf, J. Pedro F. Nunes, Markus Guehr, Renkai Li, Xiaozhe Shen, Qiang Zheng, Xijie Wang, Todd J. Martinez, Martin Centurion

Martin Centurion Publications

We have investigated the structural dynamics in photoexcited 1,2-diiodotetrafluoroethane molecules (C₂F₄I₂) in the gas phase experimentally using ultrafast electron diffraction and theoretically using FOMO-CASCI excited-state dynamics simulations. The molecules are excited by an ultraviolet femtosecond laser pulse to a state characterized by a transition from the iodine 5p orbital to a mixed 5p||σ hole and CF₂• antibonding orbital, which results in the cleavage of one of the carbon-iodine bonds. We have observed, with sub-Angstrom resolution, the motion of the nuclear wave packet of the dissociating iodine atom followed by …

Diffractive Imaging Of Dissociation And Ground-State Dynamics In A Complex Molecule, Kyle J. Wilkin, Robert M. Parrish, Jie Yang, Thomas J. A. Wolf, J. Pedro F. Nunes, Markus Guehr, Renkai Li, Xiaozhe Shen, Qiang Zheng, Xijie Wang, Todd J. Martinez, Martin Centurion

Department of Physics and Astronomy: Faculty Publications

We have investigated the structural dynamics in photoexcited 1,2-diiodotetrafluoroethane molecules (C₂F₄I₂ ) in the gas phase experimentally using ultrafast electron diffraction and theoretically using FOMO-CASCI excited-state dynamics simulations. The molecules are excited by an ultraviolet femtosecond laser pulse to a state characterized by a transition from the iodine 5p⊥ orbital to a mixed 5p ‖ σ hole and CF^•₂ antibonding orbital, which results in the cleavage of one of the carbon-iodine bonds. We have observed, with sub-Angstrom resolution, the motion of the nuclear wave packet of the dissociating iodine atom followed …

An Observational Study Of Winter Weather-Related Traffic Crashes In Nebraska, Jacob Petr

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

The responsibilities of meteorologists have evolved over time from simply providing a forecast to needing to also understand how those predictions will impact society and then communicating those risks in a clear, concise, and consistent manner. Increased motor vehicle crash numbers due to adverse weather conditions represent one such impact worthy of further study. Snowfall, in particular, significantly increases the overall risk of a crash, which can result in extensive property damage, severe injuries, and even loss of life.This project seeks to supplement traffic crash information in Nebraska by assessing how snowfall impacts crashes across the state. Crash data were …

The Role Of Boundary-Parallel Vertical Wind Shear In Convection Initiation, Alexander J. Krull

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Convection initiation (CI) remains a forecasting challenge for meteorologists. CI frequently occurs within the vicinity of some airmass boundary or density current. Airmass boundaries are favored areas of convergence, thus associated forced ascent facilitates CI. Features such as misocyclones often develop along the leading edge of airmass boundaries, favoring updraft formation and prompting alterations to the horizontal and vertical flow near the boundary. Airmass boundary characteristics and CI potential have been found to be sensitive to the environmental vertical wind shear. This affects propagation speed, convergence, and thus forced ascent along the leading edge. Previous studies have focused primarily on …

Nitrate Removal And Placement Of Floating Treatment Wetlands In The Midwest, Mary G. Keilhauer

School of Natural Resources: Dissertations, Theses, and Student Research

The Midwestern United States is vulnerable to eutrophic conditions from high nutrient concentrations. Recommendations for nonpoint source pollution management include runoff treatment (i.e., filter strips, riparian buffers) and in-situ lake treatment practices (i.e., aluminum sulfate (alum) treatments, aeration, up/downdraft pumping, floating treatment wetlands). Floating treatment wetlands (FTWs) are an innovative wetland design for nutrient removal from nonpoint sources and provide a unique in-situ treatment. Best management practice studies have commonly focused on adjacent to water practices, which have resulted in a gap for guidance for in-situ treatment placement and design. Therefore, the objectives of this project were to (1) Quantify …

Drought Impacts Assessment In Brazil - A Remote Sensing Approach, Denis Mariano

School of Natural Resources: Dissertations, Theses, and Student Research

Climate extremes are becoming more frequent in Brazil; studies project an increase in drought occurrences in many regions of the country. In the south, drought events lead to crop yield losses affecting the value chain and, therefore, the local economy. In the northeast, extended periods of drought lead to potential land degradation, affecting the livelihood and hindering local development. In the southern Amazon, an area that experienced intense land use change (LUC) in the last, the impacts are even more complex, ranging from crop yield loss and forest resilience loss, affecting ecosystem health and putting a threat on the native …

Traffic Noise And Sexual Selection: Studies Of Anthropogenic Impact On Bird Songs And Undergraduate Student Reasoning Of Evolutionary Mechanisms, Sarah Spier

School of Natural Resources: Dissertations, Theses, and Student Research

Humans have transformed much of the natural landscape and are continuing to do so at an accelerated rate, compromising natural areas that serve as important habitat for many species. Roads impact much of the environment as they fragment habitat and introduce traffic noise into the acoustic environment, deferentially affecting wildlife in roadside habitat. I explored how traffic noise affects the detection of birds based on whether their vocalizations were masked by traffic noise. Masked species detection was not affected by an increase in traffic noise amplitude, while there was a negative effect of traffic noise amplitude on unmasked species detection, …

Traffic Noise And Sexual Selection: Studies Of Anthropogenic Impact On Bird Songs And Undergraduate Student Reasoning Of Evolutionary Mechanisms, Sarah Spier

School of Natural Resources: Dissertations, Theses, and Student Research

Humans have transformed much of the natural landscape and are continuing to do so at an accelerated rate, compromising natural areas that serve as important habitat for many species. Roads impact much of the environment as they fragment habitat and introduce traffic noise into the acoustic environment, deferentially affecting wildlife in roadside habitat. I explored how traffic noise affects the detection of birds based on whether their vocalizations were masked by traffic noise. Masked species detection was not affected by an increase in traffic noise amplitude, while there was a negative effect of traffic noise amplitude on unmasked species detection, …

Evaluation Of The Metric Model For Mapping Energy Balance Components And Actual Evapotranspiration For A Super-Intensive Drip-Irrigated Olive Orchard, Samuel Ortega

School of Natural Resources: Dissertations, Theses, and Student Research

A field experiment was carried out to evaluate the METRIC (Mapping EvapoTranspiration at high Resolution Internalized with Calibration) model for mapping net radiation (Rni), soil heat flux (Gi), sensible heat flux (Hi), latent heat flux (LEi), actual evapotranspiration (ETa) and crop coefficient (Kc) of a superintensive drip-irrigated olive (Olea europeae L. cv Arbequina) orchard located in Pencahue Valley, Region del Maule, Chile (35 23’ LS; 71 44’ LW; 96 m above sea level). The study was conducted in an experimental plot of 21.1 hectares using 9 satellite images (Landsat 7 ETM+) acquired on clear sky days during 2011/2012 and 2012/2013 …

Vegetation Monitoring At Homestead National Monument Of America, Nebraska, 1998–2017, Sherry A. Leis

United States National Park Service: Publications

Executive Summary

The Heartland Inventory and Monitoring Network has sampled permanent monitoring sites in three vegetation community types (restored prairie, successional forest, and bur oak forest) at Homestead National Monument of America since 1998 (includes nine sample years). Network scientists record each species, aerial cover estimates of ground flora, diameter at breast height of midstory and overstory trees, and tree regeneration frequency (tree seedlings and saplings) within these permanent sites.

The park has experienced similar periods of drought and wetness through the monitoring record. Ground cover estimates indicate that prairie litter and bare ground are negatively related; prescribed fire cycles …

Probabilistic Analysis Of Slide-Rocking Structures Under Earthquake Loads, Taylor J. Knickerbocker

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Estimates of rare seismic hazard are essential for the resilience of critical infrastructure and facilities. However, these estimates are highly uncertain at long return periods due to the lack of observed earthquake records. Several ground motion prediction equations have been proposed to close this gap and estimate rare seismic demands; however, these models were developed based on more moderate earthquake records and can yield physically unrealizable ground motions when extrapolated to long return periods. For this reason, seismologists have proposed using precariously balanced rocks (PBRs) as a way to constrain rare seismic hazard. PBRs are a type of fragile geologic …

Optimal Design For A Causal Structure, Zaher Kmail

Department of Statistics: Dissertations, Theses, and Student Work

Linear models and mixed models are important statistical tools. But in many natural phenomena, there is more than one endogenous variable involved and these variables are related in a sophisticated way. Structural Equation Modeling (SEM) is often used to model the complex relationships between the endogenous and exogenous variables. It was first implemented in research to estimate the strength and direction of direct and indirect effects among variables and to measure the relative magnitude of each causal factor.

Historically, traditional optimal design theory focuses on univariate linear, nonlinear, and mixed models. There is no current literature on the subject of …

Developing A Framework To Link Multi-Sector Drought Impacts To Drought Severity At The State Level, Mary Noel

School of Natural Resources: Dissertations, Theses, and Student Research

The United States Drought Monitor, a weekly map depicting severity and spatial extent of drought, is a key indicator for federal and state policy decisions including the annual distribution of hundreds of millions of dollars for agricultural financial relief in the United States. However, the current table describing potential drought impacts for the map’s severity levels fails to adequately represent a state’s unique environmental, economic, and social values affected by drought. One approach to improve this broad, national-scale assessment is to transition from the former platform to a more detailed characterization of drought impacts at the state level. To accomplish …

Regime Detection Measures For The Practical Ecologist, Jessica L. Burnett

School of Natural Resources: Dissertations, Theses, and Student Research

Forecasting undesirable change is, arguably, the holy grail of ecology. Paired with an understanding of system interactions, a forecast is ideal if it provides reliable predictions in sufficient time to prevent or mitigate unwanted systemic change. Early warning systems (or early warning signals, early warning indicators) have been developed and tested for some ecological systems data, but have been mostly applied to marine fisheries time series and nutrient loadings in shallow lakes. Despite the numerous quantitative methods proposed for identifying or forecasting regime shifts in ecological data, few are used in practice. This dissertation contributes to our understanding of the …

Impact Of Robotic Challenges On Fifth Grade Problem Solving, Julie Rankin

Department of Teaching, Learning, and Teacher Education: Theses and Other Student Research

This action research project was designed to investigate the impact of educational robotics in a fifth grade rural classroom. The integration of science, technology, engineering, and math in education (STEM) has sparked an increase of robotics in the classroom. The purpose of the study was to determine if problem-solving skills can be impacted through continuing involvement with challenges using various educational robotics and programming tools. The study sought to answer two research questions: (1) How does the introduction of robotics challenges in a fifth-grade classroom impact students’ problem solving skills? (2) How do robotics in the classroom impact student interest …

The T3,T4-Conjecture For Links, Katie Tucker

Department of Mathematics: Dissertations, Theses, and Student Research

An oriented n-component link is a smooth embedding of n oriented copies of S¹ into S³. A diagram of an oriented link is a projection of a link onto R² such that there are no triple intersections, with notation at double intersections to indicate under and over strands and arrows on strands to indicate orientation. A local move on an oriented link is a regional change of a diagram where one tangle is replaced with another in a way that preserves orientation. We investigate the local moves t₃ and t₄, which are …

Quantum Chemical Calculations Applied To Somo-Homo Conversion And Vibrationally Averaged Nmr Shielding Parameters, Erik Johnson

Department of Chemistry: Dissertations, Theses, and Student Research

The inversion of frontier orbitals of free radicals was studied using density functional theory calculations in Gaussian 09. Comparisons of images of orbitals in GaussView was used to assess the relative positions of singly occupied and doubly occupied orbitals and to determine which was the highest in energy. A variety of organic free radicals were studied including several radical anions and also a neutral radical. It was found that cross-conjugation appears to be a factor in whether or not molecules show SOMO-HOMO conversion. Cross-conjugation is when two unsaturated groups are conjugated to a third unsaturated group but are not conjugated …

Analysis Of Social Unrest Events Using Spatio-Temporal Data Clustering And Agent-Based Modelling, Sudeep Basnet

Department of Computer Science and Engineering: Dissertations, Theses, and Student Research

Social unrest such as appeals, protests, conflicts, fights and mass violence can result from a wide ranging of diverse factors making the analysis of causal relationships challenging, with high complexity and uncertainty. Unrest events can result in significant changes in a society ranging from new policies and regulations to regime change. Widespread unrest often arises through a process of feedback and cascading of a collection of past events over time, in regions that are close to each other. Understanding the dynamics of these social events and extrapolating their future growth will enable analysts to detect or forecast major societal events. …