Physical Sciences and Mathematics Commons^™

Classical Theory Of Laser-Assisted Spontaneous Bremsstrahlung, H. B. Ambalampitiya, Ilya I. Fabrikant

Department of Physics and Astronomy: Faculty Publications

We study the process of laser-assisted spontaneous electron bremsstrahlung by running classical trajectories in a combined Coulomb and laser (ac) fields. Due to chaotic scattering in the combined Coulomb and ac fields, the radiation probability as a function of the impact parameter and the constant phase of the laser field exhibits fractal structures. However, these structures are smeared out when the cross section is integrated over the impact parameter and averaged over the phase. We analyze the role of different types of orbits, including the trapped orbits, and the dependence of the radiation probability on the impact parameter and the …

Extreme Site Fidelity As An Optimal Strategy In An Unpredictable And Homogeneous Environment, Brian D. Gerber, Mevin B. Hooten, Christopher P. Peck, Mindy B. Rice, James H. Gammonley, Anthony D. Apa, Amy J. Davis

United States Department of Agriculture Wildlife Services: Staff Publications

1. Animal site fidelity structures space use, population demography and ultimately gene flow. Understanding the adaptive selection for site fidelity patterns provides a mechanistic understanding to both spatial and population processes. This can be achieved by linking space use with environmental variability (spatial and temporal) and demographic parameters. However, rarely is the environmental context that drives the selection for site fidelity behaviour fully considered.

2. We use ecological theory to understand whether the spatial and temporal variability in breeding site quality can explain the site fidelity behaviour and demographic patterns of Gunnison sage‐grouse (Centrocercus minimus). We examined female site fidelity …

Quantitative Modelling Biology Undergraduate Assessment, Robert Mayes, Kent Rittschof, Joseph Dauer, Bryon Gallant

School of Natural Resources: Faculty Publications

The Quantitative Modelling Biology Undergraduate Assessment (QM BUGS Version II) assesses undergraduate biology students’ quantitative modelling abilities and confidence. The assessment is intended to be given in undergraduate biology courses where instructors are engaging students in quantitative modelling within biological contexts. The assessment consists of 36 questions: 25 multiple choice questions addressing four subcategories within quantitative modelling understanding (Quantitative Act, Quantitative Interpretation, Quantitative Modelling, and Meta-Modelling) and 11 Likert questions addressing student confidence about modelling in biology within the four subcategories. QM BUGS assessments were piloted in multiple undergraduate biology courses at both a research intensive university and regional university …

Extinction Vortex Dynamics Of Top Predators Isolated By Urbanization, John F. Benson, Peter J. Mahoney, T. Winston Vickers, Jeff A. Sikich, Paul Beier, Seth P.D. Riley, Holly B. Ernest, Walter M. Boyce

School of Natural Resources: Faculty Publications

Extinction risk is elevated in small, isolated populations due to demographic and genetic interactions. Therefore, it is critical to model these processes realistically in population viability analyses (PVA) to inform local management and contribute to a greater understanding of mechanisms within the extinction vortex. We conducted PVA’s for two small mountain lion populations isolated by urbanization in southern California to predict population growth, extinction probability, and loss of genetic diversity with empirical data. Specifically, we (1) provide the first PVA for isolated mountain lions in the Santa Ana Mountains (SAM) that considers both demographic and genetic risk factors and (2) …

Ambient Conditions Disordered-Ordered Phase Transition Of Two-Dimensional Interfacial Water Molecules Dependent On Charge Dipole Moment, Chunlei Wang, Chonghai Qi, Yusong Tu, Xuechuan Nie, Shanshan Liang

Department of Physics and Astronomy: Faculty Publications

Phase transitions of water molecules are commonly expected to occur only under extreme conditions, such as nanoconfinement, high pressure, or low temperature. We herein report the disordered-ordered phase transition of two-dimensional interfacial water molecules under ambient conditions using molecular-dynamics simulations. This phase transition is greatly dependent on the charge dipole moment, production of both charge values, and the dipole length of the solid surface. The phase transition can be identified by a sharp change in water-water interaction energies and the order parameters of the two-dimensional interfacial water monolayer, under a tiny dipole moment change near the critical dipole moment. The …

An Analysis Of Differential Reflectivity Arc Characteristics In 109 Supercell Storms, Matthew Wilson

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

Differential reflectivity (Z_DR)arcs are one of the most prominent dual-polarization features of supercell storms, and are manifest as an arc-shaped area of high Z_DR along a supercell’s forward flank reflectivity gradient. Since previous modelling studies have hypothesized that the magnitude of the drop-size sorting by the storm-relative wind which creates the arc signature is related to the strength of the low-level shear and SRH in a storm’s environment, the presence of a strong Z_DR arc is often said to indicate that a storm may have the potential to develop strong low-level rotation and potentially become tornadic. …

Dielectric Function Tensor (1.5 Ev To 9.0 Ev), Anisotropy, And Band To Band Transitions Of Monoclinic Β-(AlXGa1–X)2O3 (X ≤ 0.21) Films, Matthew Hilfiker, Ufuk Kilic, Alyssa Mock, Vanya Darakchieva, Sean Knight, Rafal Korlacki, Akhil Mauze, Yuewei Zhang, James Speck, Mathias Schubert

Department of Electrical and Computer Engineering: Faculty Publications

A set of monoclinic β-(Al_xGa_1–x)₂O₃ films coherently grown by plasma-assisted molecular beam epitaxy onto (010)-oriented β-Ga₂O₃ substrates for compositions x ≤ 0.21 is investigated by generalized spectroscopic ellipsometry at room temperature in the spectral range of 1.5 eV–9.0 eV. We present the composition dependence of the excitonic and band to band transition energy parameters using a previously described eigendielectric summation approach for β-Ga₂O₃ from the study by Mock et al. All energies shift to a shorter wavelength with the increasing Al content in …

The Adaptive Cycle: More Than A Metaphor, Shana M. Sundstrom, Craig R. Allen

School of Natural Resources: Faculty Publications

The adaptive cycle and its extension to panarchy (nested adaptive cycles) has been a useful metaphor and conceptual model for understanding long-term dynamics of change in ecological and social–ecological systems. We argue that adaptive cycles are ubiquitous in complex adaptive systems because they reflect endogenously generated dynamics as a result of processes of self-organization and evolution. We synthesize work from a wide array of fields to support this claim. If dynamics of growth, conservation, collapse and renewal are endogenous dynamics of complex adaptive systems, then there ought to be signals of system change over time that reflect this. We describe …

The State Of Canada’S Birds 2019, North American Bird Conservation Initiative Canada

Other Publications in Wildlife Management

BIRDS TELL US ABOUT THE HEALTH OF OUR WATER, AIR, AND LAND WE NEED TO LISTEN AND ACT

THE STATE OF CANADA’S BIRDS: Shorebirds, grassland birds, and aerial insectivores are in steep decline.

WATERFOWL AND WETLAND BIRDS CONSERVATION PARTNERSHIPS WORK

GRASSLAND BIRDS ARE RUNNING OUT OF TIME

SHOREBIRDS ARE LOSING GROUND

SEABIRDS A GLOBAL CONSERVATION CRISIS

FOREST BIRDS CONSERVATION WITHOUT BORDERS

BIRDS OF PREY AND AERIAL INSECTIVORES LEARNING FROM THE PAST

WHAT’S GOOD FOR BIRDS IS GOOD FOR US

CANADIANS ARE MONITORING THE STATE OF CANADA’S BIRDS

Monolayer Triphosphates Mp3 (M = Sn, Ge) With Excellent Basal Catalytic Activity For Hydrogen Evolution Reaction, Hong-Hui Wu, He Huang, Jie Zhong, Song Yu, Qiaobao Zhang, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Atomically thin two-dimensional (2D) materials have received intense research interest due to their novel properties and promising applications in nanodevices. By using density functional theory (DFT) calculations, we investigate catalytic activities of several newly predicted two-dimensional (2D) triphosphides GeP₃, SnP₃ and InP₃ monolayers for hydrogen evolution reaction (HER). The calculation results show that GeP₃ and SnP₃ monolayers are active catalysts for HER with suitable free energy of hydrogen adsorption in the basal plane. In particular, the Gibbs free energy of hydrogen adsorption (ΔG_H*) of GeP₃ is 0.024 eV, a value even …

The Prairie Naturalist, Volume 51, No. 1

The Prairie Naturalist

1 EDITOR’S NOTE

RESEARCH ARTICLES

3 Factors Affecting White Bass Abundance in Two Missouri River Reservoirs, William J. Radigan and Mark J. Fincel

17 Suitability of single-pass backpack electrofishing to estimate fish abundance and describe assemblage structure in prairie streams, Morgan J. Kauth, David A. Schumann, Katie N. B. Graeb, and W. Wyatt Hoback

NOTES

25 Channel Catfish Reproductive Traits in the Lower Platte River, Nebraska, USA - Mackenzie Zwiener, Jonathan Spurgeon, & Mark Pegg

30 Quantifying Signpost Usage By Captive Male White-Tailed Deer - Cassie L. Auxt, Eric S. Michel, and Jonathan A. Jenks.

33 Incidental Captures of Plains …

Review Of A Field Guide To The Natural World Of The Twin Cities By John J. Moriarty, Photography By Siah L. St. Clair, Douglas H. Johnson, Bonnie Sample

The Prairie Naturalist

A Field Guide to the Natural World of the Twin Cities has two foci: natural areas in the Twin Cities of Minnesota and the species that live in each. The geographical scope is the seven counties that envelop Minneapolis and Saint Paul. The author describes nine major habitat types that can be found there: prairie, savanna, big woods, oak woods, wetlands (marshes and swamps), fens and bogs, lakes, rivers, and urban and suburban. It is useful to know that “big woods” are not just woods that are large in extent, but woodlands that occur in Minnesota and western Wisconsin dominated …

Review Of Gulls Simplified: A Comparative Approach To Identification By Pete Dunne And Kevin T. Karlson, Garrett J. Macdonald

The Prairie Naturalist

The title of Pete Dunne and Kevin Karlson’s new book, Gulls Simplified, may seem like an oxymoron to many birders. Gulls are, after all, one of the most vexing groups of North American birds due to their myriad identification challenges, and many seasoned birders simply “don’t do gulls.” Indeed, Dunne, in the first line of the Introduction (page 13), writes, “Ask any bird-watcher to name the bird group that is most intimidating, and to a man, woman, and tour leader they often shout: GULLS!” The genesis of the book, and the authors’ approach to identification within, arises from the notion …

Suitability Of Single-Pass Backpack Electrofishing To Estimate Fish Abundance And Describe Assemblage Structure In Prairie Streams, Morgan J. Kauth, David A. Schumann, Katie N.B. Graeb, William Wyatt Hoback

The Prairie Naturalist

Electrofishing is commonly used by fisheries professionals to assess fish assemblage structure and species abundance in streams. Accurate estimates of fish abundance and, consequently assemblage metrics, are typically generated with mark-recapture or maximum-likelihood depletion techniques, but doing so requires considerable sampling effort. Less intensive sampling approaches may be beneficial to fisheries managers, particularly in cases where frequent sampling of many streams is preferred. We used regression and Spearman rank-order correlation analyses to compare species catch rates and the assemblage metrics generated from single-pass electrofishing samples with multiple-pass depletion abundance estimates in Nebraska streams. We examined the influence of instream habitat …

Factors Affecting White Bass Abundance In Two Missouri River Reservoirs, William J. Radigan, Mark J. Fincel

The Prairie Naturalist

Annual angler harvest of white bass (Morone chrysops) increased from 1985–2005 in Lake Oahe and Lake Sharpe, two mainstem Missouri River reservoirs in South Dakota. In 2006, harvest rates dropped appreciably in both reservoirs and remained low through 2015. It is hypothesized that a confirmed 2005 columnaris disease outbreak led to reduced annual angler harvest of white bass from both reservoirs. Mean annual angler harvest prior to the outbreak (1985–2005) in Lake Oahe decreased 65% and in Lake Sharpe decreased 57% post outbreak (2006–2015). To assess potential causes of sustained decreased adult white bass abundance in the reservoirs, …

Bird Monitoring At Homestead National Monument Of America, Nebraska, Status Report 2009–2017, David G. Peitz, Lloyd W. Morrison, Kristen L. Mecke

United States National Park Service: Publications

Executive Summary

In 2009, the Heartland Inventory Monitoring Network initiated breeding bird surveys on Homestead National Monument of America, Nebraska, to address two objectives: (1) to monitor changes in bird community composition and abundance, and (2) to improve our understanding of relationships between breeding birds and habitat, and the effects of management actions on those relationships. This report evaluates trends in the park’s breeding bird populations in the context of trends observed within the North American Bird Conservation Initiative’s (NABCI) Central Mixed Grass Prairie Bird Conservation Region, the region in which the park is located. By doing so, we can …

Bird Monitoring At Herbert Hoover National Historic Site, Iowa, Status Report 2005–2017, David G. Peitz, Lloyd W. Morrison, Kristen L. Mecke

United States National Park Service: Publications

Executive Summary

In 2005, the Heartland Inventory & Monitoring Network initiated breeding bird surveys on Herbert Hoover National Historic Site, Iowa, to address two objectives: (1) to monitor changes in bird community composition and abundance, and (2) to improve our understanding of relationships between breeding birds and habitat, and the effects of management actions on those relationships. This report evaluates trends in the park’s breeding bird populations in the context of trends observed within the North American Bird Conservation Initiative’s (NABCI) Eastern Tallgrass Prairie Bird Conservation Region , the region in which the park is located. By doing so, we …

Drought Impacts And Management In Prairie And Sandhills State Parks, Theresa M. Jedd, Devarati Bhattacharya, Cara Pesek, Michael J. Hayes

School of Natural Resources: Faculty Publications

The combination of decreased water availability and increased temperatures can interfere with outdoor activities, particularly with surface water decline and the increased risk of wildfire. Drought is a longer-term climate trend, but there is a tendency toward short-term reactions only when a drought occurs. Policy mechanisms for drought, where present, are often left to managerial discretion because they are not needed every year, and lack specific indicators. Recreator choices contribute to adaptation and public lands managers also shape drought response by monitoring meteorological trends and managing resources wisely. Despite these trends, no singular recreational drought definition exists. To understand socio-environmental …

Incidental Captures Of Plains Spotted Skunks In Central South Dakota, Samantha Fino, Joshua D. Stafford, Aaron T. Pearse, Jonathan A. Jenks

The Prairie Naturalist

The plains spotted skunk (Spilogale putorius interrupta) had a historically broad distribution in the central United States, extending from the Mississippi River west to the Rocky Mountains. This subspecies of the eastern spotted skunk (S. putorius) has experienced population declines in recent decades possibly due to habitat loss and reduction of prey through conversion of grasslands and forests to croplands, as well as reductions in abandoned buildings, fence rows, creek bottoms, and wood piles throughout the region (Crabb 1948, Kaplan and Mead 1991, Gompper and Hackett 2005, Sasse 2017). Woody debris provides access to prey, and …

Channel Catfish Reproductive Traits In The Lower Platte River, Nebraska, Usa, Mackenzie Zwiener, Jonathan J. Spurgeon, Mark Pegg

The Prairie Naturalist

Reproductive traits including fecundity, egg diameter, and condition of freshwater fishes influence offspring survival and abundance and may provide insight regarding timing of reproduction (Winemiller and Rose 1992, Johnston and Leggett 2002). Fish size (i.e., length or weight) may influence the number of eggs produced by an individual female (i.e., fecundity; Michaletz 1998). Larger individuals may, thus, disproportionately contribute to year-classes through increased fecundity if egg and larval survival is similar or greater than those from smaller reproductive females (Gwinn et al. 2015). Likewise, maternal fish size may influence egg diameter and offspring survival, whereby larger egg diameters are associated …

Umphlett Qci June 2019, Natalie Umphlett

High Plains Regional Climate Center: Personnel Publications

Highlights for the Basin

Temperature and Precipitation Anomalies

Soil Moisture Conditions

Delayed/Prevented Planting

Impacts to Cattle

Damage to Infrastructure

Temperature

Precipitation

A Data Driven Approach To Identify Journalistic 5ws From Text Documents, Venkata Krishna Mohan Sunkara

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

Textual understanding is the process of automatically extracting accurate high-quality information from text. The amount of textual data available from different sources such as news, blogs and social media is growing exponentially. These data encode significant latent information which if extracted accurately can be valuable in a variety of applications such as medical report analyses, news understanding and societal studies. Natural language processing techniques are often employed to develop customized algorithms to extract such latent information from text.

Journalistic 5Ws refer to the basic information in news articles that describes an event and include where, when, who, what and why …

Voltage Controlled Magnetism In Cr2o3 Based All-Thin-Film Systems, Junlei Wang, Will Echtenkamp, Ather Mahmood, Christian Binek

Christian Binek Publications

Voltage-control of exchange biases through active selection of distinct domain states of the magnetoelectric and antiferromagnetic pinning layer is demonstrated for Cr2O3/CoPd heterostructures. Progress and obstacles towards an isothermal switching of exchange bias are discussed. An alternative approach avoiding exchange bias for voltage-controlled memory exploits boundary magnetization at the surface of Cr2O3 as voltage-controlled state variable. We demonstrate readout and switching of boundary magnetization in ultra-thin Cr2O3/Pt Hall bar devices where reversal of boundary magnetization is achieved via magnetoelectric annealing with simultaneously applied ±0.5 V and 400 mT electric and magnetic fields.

Analysing Habitat Connectivity And Home Ranges Of Bigmouth Buffalo And Channel Catfish Using A Large-Scale Acoustic Receiver Network, Eva C. Enders, Colin Charles, Douglas A. Watkinson, Colin Kovachik, Douglas R. Leroux, Henry Hansen, Mark Pegg

School of Natural Resources: Faculty Publications

The determination if fish movement of potadromous species is impeded in a river system is often difficult, particularly when timing and extent of movements are unknown. Furthermore, evaluating river connectivity poses additional challenges. Here, we used large-scale, long-term fish movement to study and identify anthropogenic barriers to movements in the Lake Winnipeg basin including the Red, Winnipeg, and Assiniboine rivers. In the frame of the project, 80 Bigmouth Buffalo (Ictiobus cyprinellus) and 161 Channel Catfish (Ictalurus punctatus) were tagged with acoustic transmitters. Individual fish were detected with an acoustic telemetry network. Movements were subsequently analyzed using a continuous-time Markov model …

River-Wide Habitat Availability For Fish Habitat Guilds: Implications For In-Stream Flow Protection, Jonathan Spurgeon, Mark A. Pegg, Piotr Parasiewicz, Joe Rogers

School of Natural Resources: Faculty Publications

The variation in river discharge alters habitat heterogeneity with implications for the distribution of fish species with different habitat requirements. Assessments of habitat availability following changes in river discharge are difficult to apply at broad spatial scales and with relevance to multiple species. We used a MesoHABSIM modeling approach to quantify river-wide changes in habitat availability for five fish habitat guilds under three river discharge levels along the Niobrara River, NE, USA.We used a time-series of river discharge (1958–2010) to create uniform continuous under-threshold habitat duration curves that identified habitat conditions that may result in periods of stress for fish …

Performance Of Plastic Electron Optics Components Fabricated Using A 3d Printer, Phillip Wiebe, Peter Beierle, Hua-Chieh Shao, Bret Gergely, Anthony F. Starace, Herman Batelaan

Anthony F. Starace Publications

We show images produced by an electron beam deflector, a quadrupole lens and a einzel lens fabricated from conducting and non-conducting plastic using a 3D printer. Despite the difficulties associated with the use of plastics in vacuum, such as outgassing, poor conductivity, and print defects, the devices were used successfully in vacuum to steer, stretch and focus electron beams to millimeter diameters. Simulations indicate that much smaller focus spot sizes might be possible for such 3D-printed plastic electron lenses taking into account some possible surface defects. This work was motivated by our need to place electron optical components in difficult-to-access …

Seasonal Dynamics Of Lipid Metabolism And Energy Storage In The Brazilian Free-Tailed Bat, Elizabeth J. Rogers, Amie S. Sommers, Liam P. Mcguire

School of Natural Resources: Faculty Publications

As small, flying, mammalian endotherms, insectivorous bats are adapted to operate at high levels of energy expenditure. In response to seasonally variable challenges, we predicted that bats should balance energy budgets by flexibly adjusting aspects of their physiology or behavior in ways that elevate metabolic capacity. We examined variation in energy storage and pathways for oxidative metabolism in Brazilian free-tailed bats (Tadarida brasiliensis) related to estimated costs associated with reproduction and migration. We collected pectoral muscle and liver from female T. brasiliensis at six time points during the summer and fall and measured changes in the activity of four enzymes …

New Heusler Compounds In Ni-Mn-In And Ni-Mn-Sn Alloys, Xingzhong Li, W.-Y. Zhang, Shah R. Valloppilly, David J. Sellmyer

Nebraska Center for Materials and Nanoscience: Faculty Publications

Rapidly quenched ternary Ni-Mn-T (T = In, Sn) alloys exhibit features associated with magnetic skyrmions, so that XRD, TEM, EDS, SAED and HREM investigations were carried out for structural characterization on the two alloy systems. In this paper, we report a new type of Mn-rich Heusler compound with a cubic unit cell, a = 0.9150 nm in Ni-Mn-In and a = 0.9051 nm in Ni-Mn-Sn, which coexist with a Ni-rich full-Heusler compound with defects, a = 0.6094 nm in Ni-Mn-In and a = 0.6034 nm in Ni-Mn-Sn. A further analysis of the experimental results reveals a close structural relationship between …

Analytic Generalized Description Of A Perturbative Nonparaxial Elegant Laguerre-Gaussian Phasor For Ultrashort Pulses In The Time Domain, Andrew Vikartofsky, Ethan C. Jahns, Anthony F. Starace

Anthony F. Starace Publications

An analytic expression for a polychromatic phasor representing an arbitrarily short elegant Laguerre-Gauss (eLG) laser pulse of any spot size and LG mode is presented in the time domain as a nonrecursive, closed-form perturbative expansion valid to any order of perturbative correction. This phasor enables the calculation of the complex electromagnetic fields for such beams without requiring the evaluation of any Fourier integrals. It is thus straightforward to implement in analytical or numerical applications involving eLG pulses.

Space-Charge Limited Conduction In Epitaxial Chromia Films Grown On Elemental And Oxide-Based Metallic Substrates, C.-P. Kwan, Mike Street, Ather Mahmood, Will Echtenkamp, M. Randle, K. He, J. Nathawat, N. Arabchigavkani, B. Barut, S. Yin, R. Dixit, Uttam Singisetti, Christian Binek, J. P. Bird

Christian Binek Publications

We study temperature dependent (200 – 400 K) dielectric current leakage in high-quality, epitaxial chromia films, synthesized on various conductive substrates (Pd, Pt and V2O3). We find that trap-assisted space-charge limited conduction is the dominant source of electrical leakage in the films, and that the density and distribution of charge traps within them is strongly dependent upon the choice of the underlying substrate. Pd-based chromia is found to exhibit leakage consistent with the presence of deep, discrete traps, a characteristic that is related to the known properties of twinning defects in the material. The Pt- and V2O3-based films, in contrast, …