Digital Commons Network^™

A Model Of Tuberculosis Transmission And Intervention Strategies In An Urban Residential Area, Elsje Pienaar, Aaron M. Fluitt, Scott E. Whitney, Alison G. Freifeld, Hendrik J. Viljoen

Department of Chemical and Biomolecular Engineering: Faculty Publications

The model herein aims to explore the dynamics of the spread of tuberculosis (TB) in an informal settlement or township. The population is divided into households of various sizes and also based on commuting status. The model dynamics distinguishes between three distinct social patterns: the exposure of commuters during travel, random diurnal interaction and familial exposure at night. Following the general SLIR models, the population is further segmented into susceptible (S), exposed/latently infected (L), active/infectious (I), and recovered (R) individuals. During the daytime, commuters travel on public transport, while non-commuters randomly interact in the community to mimic chance encounters with …

Corrosion Of Steel Shipwrecks In The Marine Environment: Uss Arizona—Part 2, Donald L. Johnson, Brent M. Wilson, James D. Carr, Matthew A. Russell, Larry E. Murphy, David L. Conlin

Department of Chemistry: Faculty Publications

This article is a continuation of Part 1 (October 2006 MP) on the USS Arizona hull. It discusses additional methods being investigated for use in determining corrosion rates with a minimal impact on the existing structure. Marine biofouling (concretion) has accumulated on the hull. Concretion samples have been studied using x-ray diffraction, environmental electron microscopy, and corrosion potential (E_corr) to characterize the relationship between concretion and the steel substrate. The data presented in this study confirm the viability of concretion analysis as a minimum-impact procedure to estimate the corrosion rate of mild steel in seawater.

Corrosion Of Civil War Era Sub Marine Explorer—Part 2, Donald L. Johnson, James D. Carr, Brent M. Wilson, Larry E. Murphy, James P. Delgado

Department of Chemistry: Faculty Publications

The Sub Marine Explorer was designed and built by Julius H. Kroehl, who was born in Prussia in 1820. After migrating to the United States in 1838 and becoming a citizen, he served in the Union Navy (United States Navy during the Civil War) as an underwater demolitions expert. He left the Navy in 1863 and began designing a “sub-marine” that would facilitate Union forces’ mine removal and obstruction clearance. At the end of the Civil War, he became an engineer for the Pacific Pearl Co., an organization interested in using the craft to recover pearls from deep sea oyster …

Corrosion Of Civil War Era Sub Marine Explorer—Part 1, Donald L. Johnson, James D. Carr, Brent M. Wilson, Larry E. Murphy, James P. Delgado

Department of Chemistry: Faculty Publications

The Sub Marine Explorer is one of five submersibles (submarines) constructed prior to 1870 that have survived either in museums or as in situ archaeological sites around the world. Since 1869, the wreck of Explorer has emerged at low tide on the beach of Isla San Telmo, Archipiélago de las Perlas, Panama, located ~75 km southwest of Panama City in the Bay of Panama. In 2001, James Delgado visited the site. Locals described the wreck as a World War II-era Japanese midget submarine. Delgado consulted with Richard Wills, an expert on American Civil War submarines, and confirmed that the well-preserved …

Recent Advances In Global Lake Coring Hold Promise For Global Change Research In Paleolimnology, Walter E. Dean

United States Geological Survey: Staff Publications

Thank you, Antje, for your generous comments and I thank IPA for presenting me with this award along with three giants of paleolimnology! I am humbled and delighted to accept this award as a representative of all those in the Paleolimnology community whose creative insights continue to make Paleolimnology inspiring.

The Influence Of Topology On Hydraulic Conductivity In A Sand-And-Gravel Aquifer, Roger H. Morin, Denis R. Leblanc, Brent M. Troutman

United States Geological Survey: Staff Publications

A field experiment consisting of geophysical logging and tracer testing was conducted in a single well that penetrated a sand-and-gravel aquifer at the U.S. Geological Survey Toxic Substances Hydrology research site on Cape Cod, Massachusetts. Geophysical logs and flowmeter/pumping measurements were obtained to estimate vertical profiles of porosity ϕ, hydraulic conductivity K, temperature, and bulk electrical conductivity under background, freshwater conditions. Saline-tracer fluid was then injected into the well for 2 h and its radial migration into the surrounding deposits was monitored by recording an electromagnetic-induction log every 10 min. The field data are analyzed and interpreted primarily …

Heat Flow And Hydrologic Characteristics At The And-1b Borehole, Andrill Mcmurdo Ice Shelf Project, Antarctica, Roger H. Morin, Trevor Williams, Stuart A. Henrys, Diana Magens, Frank Niessen, Dhiresh Hansaraj

United States Geological Survey: Staff Publications

The Antarctic Drilling Program (ANDRILL) successfully drilled and cored a borehole, AND-1B, beneath the McMurdo Ice Shelf and into a flexural moat basin that surrounds Ross Island. Total drilling depth reached 1285 m below sea floor (mbsf) with 98 percent core recovery for the detailed study of glacier dynamics. With the goal of obtaining complementary information regarding heat fl ow and permeability, which is vital to understanding the nature of marine hydrogeologic systems, a succession of three temperature logs was recorded over a five day span to monitor the gradual thermal recovery toward equilibrium conditions. These data were extrapolated to …

Scale‐Invariant Stress Orientations And Seismicity Rates Near The San Andreas Fault, Amy Day-Lewis, Mark D. Zoback, Stephen Hickman

United States Geological Survey: Staff Publications

We analyzed measurements of the direction of maximum horizontal compressive stress as a function of depth in two scientific research wells near the San Andreas Fault in central and southern California. We found that the stress orientations exhibit scale‐invariant fluctuations over intervals from tens of cm to several km. Similarity between the scaling of the stress orientation fluctuations and the scaling of earthquake frequency with fault size suggests that these fluctuations are controlled by stress perturbations caused by slip on faults of various sizes in the critically‐stressed crust adjacent to the fault. The apparent difference in stress scaling parameters between …

The Ties That Bind: Soil Surveyor William Edgar Tharp And Oceanographic Cartographer Marie Tharp, Edward R. Landa

United States Geological Survey: Staff Publications

The link between soil science and geology is personified in the American father and daughter: soil surveyor William Edgar Tharp (1870–1959) and oceanographic cartographer Marie Tharp (1920–2006). From 1904 to 1935, W.E. Tharp mapped soils in 14 states for the US Department of Agriculture, and campaigned during the late 1920s–early 1930s to raise awareness of the high rates of soil erosion from croplands. The lifestyle of the federal soil surveyor in the United States during the early 20th century involved frequent household moves, and it played a formative role in Marie Tharp’s childhood. Her path to a career in geology …

History And Dating Of The Publication Of The Philadelphia (1822) And London (1823) Editions Of Edwin James’S Account Of An Expedition From Pittsburgh To The Rocky Mountains, Neal Woodman

United States Geological Survey: Staff Publications

The public record of Major Stephen H. Long’s 1819–1820 exploration of the American north-west, Account of an expedition from Pittsburgh to the Rocky Mountains, compiled by Edwin James, contains valuable contributions regarding the natural landscapes, native peoples and wildlife of a mostly unexplored region of the American west compiled from the notes of some of America’s foremost naturalists, and it includes the first descriptions of 67 new species. The original plan was to publish the Account in Philadelphia and London simultaneously, yet these two editions differ substantially in ways that are relevant to the taxonomic contributions in the work. …

A Pattern Of Patience: On Providing Technical Direction For King Lear, Theron L. Seckington

Johnny Carson School of Theatre and Film: Theses, Student Research, and Creative Work

The following writing will document my process as technical director for the 2009 mainstage production of King Lear at the Johnny Carson School of Theatre and Film (JCSTF) at the University of Nebraska – Lincoln (UNL). King Lear was directed by Virginia Smith with scenery designed by fellow Master of Fine Arts (MFA) candidate Patric Vendetti, lights by senior Angela Sharman, and sound by sophomore Max Holm. Costumes were designed by MFA candidate Cecilia Sickler. The shop foreman was Bryan Ruhs, and the production was stage managed by junior Amber Naylor. I was advised by JCSTF technical director Edward Stauffer. …

A Simple Model To Predict Scalar Dispersion Within A Successively Thinned Loblolly Pine Canopy, Steven L. Edburg, Gene Allwine, Brian Lamb, David Stock, Harold Thistle, Holly Peterson, Brian Strom

United States Department of Agriculture, Forest Service / University of Nebraska-Lincoln: Faculty Publications

Bark beetles kill millions of acres of trees in the United States annually by using chemical signaling to attack host trees en masse. As an attempt to control infestations, forest managers use synthetic semiochemical sources to attract beetles to traps and/or repel beetles from high-value resources such as trees and stands. The purpose of this study was to develop a simple numerical technique that may be used by forest managers as a guide in the placement of synthetic semiochemicals. The authors used a one-dimensional, one-equation turbulence model (k–l_m) to drive a three-dimensional transport and dispersion model. Predictions …

A Non-Vacuum Process For Preparing Nanocrystalline Cuin1−XGaXSe2 Materials Involving An Open-Air Solvothermal Reaction, J. Olejníček, Chad A. Kamler, A. Mirasano, A. L. Martinez-Skinner, M. A. Ingersoll, C. L. Exstrom, S. A. Darveau, J. L. Huguenin-Love, M. Diaz, Natale J. Ianno, Rodney J. Soukup

Department of Electrical and Computer Engineering: Faculty Publications

A non-vacuum, two-step process has been used to prepare a series of nanocrystalline CuIn_1−xGa_xSe₂ (x = 0, 0.25, 0.5, 0.75, 1) materials. An open-air solvothermal preparation in triethylenetetramine solvent was followed by annealing at 500 °C in a nitrogen atmosphere for 20 min. All materials have mixed clustered plate, spherical particle, and nanorod morphologies with the smallest particle diameters ranging between 20 and 40 nm. Raman spectroscopy and X-ray diffraction (XRD) confirm that indium/gallium ratio control is possible over a wide range. The solvothermal reaction step yields a mixture of chalcopyrite and Cu …

Hydrogen In Inn: A Ubiquitous Phenomenon In Molecular Beam Epitaxy Grown Material, V. Darakchieva, K. Lorenz, N. P. Barradas, E. Alves, B. Monemar, Mathias Schubert, N. Franco, C. L. Hsiao, L. C. Chen, W. J. Schaff, L. W. Tu, T. Yamaguchi, Y. Nanishi

Department of Electrical and Computer Engineering: Faculty Publications

We study the unintentional H impurities in relation to the free electron properties of state-of-the-art InN films grown by molecular beam epitaxy (MBE). Enhanced concentrations of H are revealed in the near surface regions of the films, indicating postgrowth surface contamination by H. The near surface hydrogen could not be removed upon thermal annealing and may have significant implications for the surface and bulk free electron properties of InN. The bulk free electron concentrations were found to scale with the bulk H concentrations while no distinct correlation with dislocation density could be inferred, indicating a major role of hydrogen for …

Exploring Science Through Media: The Omaha Science Media Project 2009–2010, Belita Kalala, Scott Barry, Rebecca Aiken, Soo Hui-Lee, Mary Claire Rice, Elizabeth Gamez, Nkem Kalu, Amy Struthers, Adam Wagler, Bruce Mitchell, Julie Nichols

College of Journalism and Mass Communications: Student Advertising Projects

The Omaha Science Media Project represents the efforts of more than a hundred people across eight organizations. Working together, these individuals explored innovations in teaching and learning science that challenged and contributed to Omaha’s learning community. This program owes tremendous gratitude to Katie Weitz White and the Sherwood Foundation for their vision, support, and enthusiasm. The Sherwood Foundation’s work has been critical to inspiring students, energizing teachers, and building strong programs for all. We also thank the Omaha Schools Foundation for its guidance and support. The project’s principal investigator is Judy Diamond, Ph.D., Professor and Curator of Informal Science Education …

Numerical And Analytical Verification Of A Multiscale Computational Model For Impact Problems In Heterogeneous Viscoelastic Materials With Evolving Damage, Bruno Bachiega Araujo

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

Composites are engineered materials that take advantage of the particular properties of each of its two or more constituents. They are designed to be stronger, lighter and to last longer which can lead to the creation of safer protection gear, more fuel efficient transportation methods and more affordable materials, among other examples.

This thesis proposes a numerical and analytical verification of an in-house developed multiscale model for predicting the mechanical behavior of composite materials with various configurations subjected to impact loading. This verification is done by comparing the results obtained with analytical and numerical solutions with the results found when …

Anoxic Treatment Wetlands For Denitrification, Harold L. Leverenz, Kristine Haunschild, Guy Hopes, George Tchobanoglous, Jeannie L. Darby

United States Army Corps of Engineers, Omaha District

Anoxic subsurface flow (SSF) constructed wetlands were evaluated for denitrification using nitrified wastewater. The treatment wetlands utilized a readily available organic woodchip-media packing to create the anoxic conditions. After 2 years in operation, nitrate removal was found to be best described by first-order kinetics. Removal rate constants at 20°C (k₂₀) were determined to be 1.41–1.30 d⁻¹, with temperature coefficients (θ) of 1.10 and 1.17, for planted and unplanted experimental woodchip-media SSF wetlands, respectively. First-order removal rate constants decreased as length of operation increased; however, a longer-term study is needed to establish the steady-state …

The Easy Case For Products Liability: A Response To Polinsky & Shavell, Benjamin C. Zipursky, John C.P. Goldberg

Faculty Scholarship

In their article “The Uneasy Case for Product Liability,” Professors Polinsky and Shavell assert the extraordinary claim that there should be no tort liability - none at all - for injuries caused by widely-sold products. In particular, they claim to have found convincing evidence that the threat of tort liability creates no additional incentives to safety beyond those already provided by regulatory agencies and market forces, and that tort compensation adds little or no benefit to injury victims beyond the compensation already provided by various forms of insurance. In this response, we explain that, even on its own narrow terms, …

Robust Isothermal Electric Control Of Exchange Bias At Room Temperature, Xi He, Ning Wu, Anthony N. Caruso, Elio Vescovo, Kirill D. Belashchenko, Peter A. Dowben, Christian Binek

Kirill Belashchenko Publications

Voltage-controlled spin electronics is crucial for continued progress in information technology. It aims at reduced power consumption, increased integration density and enhanced functionality where non-volatile memory is combined with highspeed logical processing. Promising spintronic device concepts use the electric control of interface and surface magnetization. From the combination of magnetometry, spin-polarized photoemission spectroscopy, symmetry arguments and first-principles calculations, we show that the (0001) surface of magnetoelectric Cr₂O₃ has a roughness-insensitive, electrically switchable magnetization. Using a ferromagnetic Pd/Co multilayer deposited on the (0001) surface of a Cr₂O₃ single crystal, we achieve reversible, room-temperature isothermal switching …

Ab Initio Calculations And Ellipsometry Measurements Of The Optical Properties Of The Layered Semiconductor In4Se3, L. Makinistian, E. A. Albanesi, N. V. Gonzalez Lemus, A. G. Petukhov, D. Schmidt, Eva Schubert, M. Schubert, Yaroslav B. Losovyj, P. Galiy, Peter A. Dowben

Peter Dowben Publications

In this work, we present a thorough study of the optical properties of the layered orthorhombic compound In₄Se₃. The dielectric function—real and imaginary parts, the complex refraction index, the reflectivity, the absorption coefficient, and the conductivity of In₄Se₃ were calculated with the inclusion of the spin-orbit interaction, using an ab initio FP-LAPW method based on DFT. Also, generalized ellipsometry was employed for more precise measurement of the anisotropic dielectric functions for polarization along crystal a, b, and c axes of orthorhombic absorbing In₄Se₃ single crystals cut approximately parallel to …

The Local Structure Of Transition Metal Doped Semiconducting Boron Carbides, Jing Liu, Guangfu Luo, Wai-Ning Mei, Orhan Kizilkaya, Eric D. Shepherd, Jennifer I. Brand, Peter A. Dowben

Peter Dowben Publications

Transition metal doped boron carbides produced by plasma enhanced chemical vapour deposition of orthocarborane (closo-1,2-C₂B₁₀H₁₂) and 3d metal metallocenes were investigated by performing K-edge extended x-ray absorption fine structure and x-ray absorption near edge structure measurements. The 3d transition metal atom occupies one of the icosahedral boron or carbon atomic sites within the icosahedral cage. Good agreement was obtained between experiment and models for Mn, Fe and Co doping, based on the model structures of two adjoined vertex sharing carborane cages, each containing a transition metal. The local spin configurations of all …

Where Cultures And Sovereigns Collide: Balancing Federalism, Tribal Self-Determination, And Individual Rights In The Adoption Of Indian Children By Gays And Lesbians, Steve Sanders

Articles by Maurer Faculty

This article analyzes the complex interplay between adoption (traditionally a matter reserved to state family law) and the federal Indian Child Welfare Act in the context of adoptions by gays and lesbians.

As a federal statute that partially preempts state law for the benefit of Native Americans, ICWA implicates three sovereigns: the United States, the state where the adoption petition is brought, and the tribe whose child is the focus of the proceeding. This interplay of sovereigns in itself makes Indian child welfare law complicated and interesting. Beyond these sovereign interests, also to be considered are the interests and rights …

Dynamic Creation: Extending The Radical Austrian Approach To Entrepreneurship, Todd H. Chiles, Chris S. Tuggle, Jeffery S. Mcmullen, Leonard Bierman, Daniel W. Greening

Department of Management: Faculty Publications

We develop a new perspective on entrepreneurship as a dynamic, complex, subjective process of creative organizing. Our approach, which we call ‘dynamic creation’, synthesizes core ideas from Austrian ‘radical subjectivism’ with complementary ideas from psychology (empathy), strategy and organization theory (modularity), and complexity theory (self-organization). We articulate conjectures at multiple levels about how such dynamic creative processes as empathizing, modularizing, and self-organizing help organize subjectively imagined novel ideas in entrepreneurs’ minds, heterogeneous resources in their firms, and disequilibrium markets in their environments. In our most provocative claim, we argue that entrepreneurs, by imagining divergent futures and (re)combining heterogeneous resources to …

An Experimental Study Of The Impact Of Psychological Capital On Performance, Engagement, And The Contagion Effect, Timothy Daniel Hodges

College of Business: Dissertations, Theses, and Student Research

Psychological Capital, or PsyCap, is a core construct consisting of the positive psychological resources of efficacy, hope, optimism, and resilience. Previous research has consistently linked PsyCap to workplace outcomes including employee attitudes, behaviors, and performance. Further research has explored the ways in which PsyCap can be developed through relatively brief workplace interventions. The present study focuses on PsyCap development and the relationship to employee engagement and performance. In an experimental design with random assignment of subjects to control group (n = 52 managers and 152 associates) and treatment group (n = 58 managers and 239 employees), a field sample of …

American Economic Development, Managerial Corporate Capitalism, And The Institutional Foundations Of The Modern Income Tax, Ajay K. Mehrotra

Articles by Maurer Faculty

Histories of the modern American income tax have generally focused on the role that social and political forces have played in the development of a new tax system. This article seeks to move beyond the social and political determinants to examine the economic factors that facilitated the adoption of the modern, graduated income tax. Without marginalizing the importance of social and political factors, the central aim of this article is to make a modest contribution to the legal and political historiography of the U.S. income tax by highlighting how changing material economic conditions afforded social groups, political reformers, and lawmakers …

Finite Element Analysis Of Cracks In Aging Aircraft Structures With Bonded Composite-Patch Repairs, Linxia Gu, Ananth Ram Mahanth Kasavajhala, Shijia Zhao

Department of Mechanical and Materials Engineering: Faculty Publications

Bonded composite-patch repair has been used to transfer load from cracked structures to the reinforcement such that subsequent crack propagation is reduced. In this study,the mechanical behavior of a single edge v-notch A17075-T6 plate repaired with 1-ply and 4-ply composite patches was investigated through the finite element method. Contour integral method was used to define and evaluate the stress intensity factors at the crack tip. The effect of the adhesive epoxy film, patch material, thickness and ply orientations on the evolution of the stress intensity factor (SIF) of the repaired structure was examined. The results indicated that the SIF of …

Thermal Models Of Railroad Wheels And Bearings, Kevin D. Cole, Constantine M. Tarawneh, Arturo A. Fuentes, B. M. Wilson, L. Navarro

Department of Mechanical and Materials Engineering: Faculty Publications

The rolling surface for railroad wheels can be a heat source that may have an impact on the performance of the wheel bearing. In this study, experimental data from an electrically-heated railroad wheel set is analyzed by constructing thermal models of the wheel set. A steady finite-element model, a steady-analytical model, and a transient lumped-parameter model are discussed. Model parameters are determined from careful comparisons with the experimental data. The lumped-parameter model given here is intended as a simple predictive tool for determining when wheel heating caused by rail operations will have an impact on bearing temperature. The model parameters …

Damned For Their Judgment: The Tort Liability Of Standard Development Organizations, Robert H. Heidt

Articles by Maurer Faculty

No abstract provided.

Adaptive Management In The Courts, Robert L. Fischman, J. B. Ruhl

Articles by Maurer Faculty

Adaptive management has become the tonic of natural resources policy. With its core idea of “learning while doing,” adaptive management has infused the natural resources policy world to the point of ubiquity, surfacing in everything from mundane agency permits to grand presidential proclamations. Indeed, it is no exaggeration to suggest that these days adaptive management is natural resources policy. But is it working? Does appending “adaptive” in front of “management” somehow make natural resources policy, which has always been about balancing competing claims to nature’s bounty, something more and better? Many legal and policy scholars have asked that question, with …

Force–Frequency Effect Of Thickness Mode Langasite Resonators, Haifeng Zhang, Joseph A. Turner, Jiashi Yang, John A. Kosinski

Department of Mechanical and Materials Engineering: Faculty Publications

Langasite resonators are of recent interest for a variety of applications because of their good temperature behavior, good piezoelectric coupling, low acoustic loss and high Q factor. The force–frequency effect describes the shift in resonant frequency a resonator experiences due to the application of a mechanical load. A clear understanding of this effect is essential for many design applications such as pressure sensors. In this article, the frequency shift is analyzed theoretically and numerically for thin, circular langasite plates subjected to a pair of diametrical forces. In addition, the sensitivity of the force–frequency effect is analyzed with respect to the …