Physical Sciences and Mathematics Commons^™

Evaluating And Regulating Lead In Artificial Turf, Gregory Van Ulirsch, Kevin Gleason, Shawn Gerstenberger, Deaphne B. Moffett, Glenn Pulliam, Tariq Ahmed, Jerald Fagliano

Environmental & Occupational Health Faculty Publications

Background: In 2007, a synthetic turf recreational field in Newark, New Jersey, was closed because lead was found in synthetic turf fibers and in surface dust at concentrations exceeding hazard criteria. Consequently, public health professionals across the country began testing synthetic turf to determine whether it represented a lead hazard. Currently, no standardized methods exist to test for lead in synthetic turf or to assess lead hazards.

Objectives: Our objectives were to increase awareness of potential lead exposure from synthetic turf by presenting data showing elevated lead in fibers and turf-derived dust; identify risk assessment uncertainties; recommend that federal and/or …

A New Perspective On Visual Word Processing Efficiency, Joseph W. Houpt, James T. Townsend

Psychology Faculty Publications

As a fundamental part of our daily lives, visual word processing has received much attention in the psychological literature. Despite the well established perceptual advantages of word and pseudoword context using accuracy, a comparable effect using response times has been elusive. Some researchers continue to question whether the advantage due to word context is perceptual. We use the capacity coefficient, a well established, response time based measure of efficiency to provide evidence of word processing as a particularly efficient perceptual process to complement those results from the accuracy domain.

A Modelling Approach To Evaluate Potential Management Actions Designed To Increase Growth Of White Perch In A High-Density Population, Christopher J. Chizinski, Kevin L. Pope, G.R. Wilde

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

A deterministic, age-structured population model was developed to simulate potential management scenarios designed to increase growth of individuals (quantified by maximum length) in a hypothetical population of white perch, Morone americana (Gmelin). Four scenarios were developed that included non-selective mortality of adult white perch, increased mortality of age groups most influential on population growth, increased age-0 mortality and inhibiting recruitment after spawning. The greatest increase in maximum length occurred with nonselective adult mortality when population biomass was reduced by 97%; lesser increases in maximum length were achieved with the other management scenarios. Populations returned to their original state after control …

Methods For Assessing Fish Populations, Kevin L. Pope, Steve E. Lochmann, Michael K. Young

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Fisheries managers are likely to assess fish populations at some point during the fisheries management process. Managers that follow the fisheries management process (see Chapter 5) might find their knowledge base insufficient during the steps of problem identification or management action and must assess a population before appropriate actions can be taken. Managers will implement some type of assessment during the evaluation step as a means of measuring progress relative to objectives. Choosing how to assess a population is an important decision because managers strive to maximize their knowledge of a population while minimizing the time and money expended to …

The Index Of Biological Integrity And The Bootstrap: Can Random Sampling Error Affect Stream Impairment Decisions?, Christine L. Dolph, Aleksey Y. Sheshukov, Christopher J. Chizinski, Bruce Vondracek, Bruce N. Wilson

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Multimetric indices, such as the Index of Biological Integrity (IBI), are increasingly used bymanagement agencies to determine whether surface water quality is impaired. However, important questions about the variability of these indices have not been thoroughly addressed in the scientific literature. In this study, we used a bootstrap approach to quantify variability associated with fish IBIs developed for streams in two Minnesota river basins. We further placed this variability into a management context by comparing it to impairment thresholds currently used in water quality determinations for Minnesota streams. We found that 95% confidence intervals ranged as high as 40 points …

Methods For Assessing Fish Populations, Kevin L. Pope, Steve E. Lochmann, Michael K. Young

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Fisheries managers are likely to assess fish populations at some point during the fisheries management process. Managers that follow the fisheries management process (see Chapter 5) might find their knowledge base insufficient during the steps of problem identification or management action and must assess a population before appropriate actions can be taken. Managers will implement some type of assessment during the evaluation step as a means of measuring progress relative to objectives. Choosing how to assess a population is an important decision because managers strive to maximize their knowledge of a population while minimizing the time and money expended to …

Evaluating Food Availability And Nest Predation Risk As Sources Of Bias In Aural Bird Surveys, Bruce A. Robertson, Richard L. Hutto, Joseph J. Fontaine

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

The use of aural surveys to estimate population parameters is widespread in avian studies.Despite efforts to increase the efficacy of this method, the potential for ecological context to bias population estimates remains largely unexplored. For example, food availability and nest predation risk can influence singing activity independent of density and, therefore, may bias aural estimates where these ecological factors vary systematically among habitats or other categories of ecological interest. We used a natural fire event in a mixed-conifer forest that experienced variation in fire severity (low, intermediate, and high) to determine if aural surveys produce accurate density estimates of Dark-eyed …

Lattice Dynamical Probe Of Charge Order And Antipolar Bilayer Stacking In Lufe2o4, X. S. Xu, J. De Groot, Q.-C. Sun, B. C. Sales, D. Mandrus, M. Angst, A. P. Litvinchuk, J. L. Musfeldt

Xiaoshan Xu Papers

We investigated the infrared response of LuFe₂O₄ through the series of charge, magnetic, and structural transitions. All vibrational modes couple strongly to the charge order, whereas the LuO zone-folding modes are also sensitive to magnetic order and structural distortion. The dramatic splitting of the LuO₂ layer mode is attributed to charge-rich/poor proximity effects and its temperature dependence reveals the antipolar nature of the W layer pattern.

Optical Properties Of Quasi-Tetragonal Bifeo3 Thin Films, P. Chen, N. J. Podraza, X. S. Xu, A. Melville, E. Vlahos, V. Gopalan, R. Ramesh, D. G. Schlom, J. L. Musfeldt

Xiaoshan Xu Papers

Optical transmission spectroscopy and spectroscopic ellipsometry were used to extract the optical properties of an epitaxially grown quasi-tetragonal BiFeO₃ thin film in the near infrared to near ultraviolet range. The absorption spectrum is overall blue shifted compared with that of rhombohedral BiFeO₃, with an absorption onset near 2.25 eV, a direct 3.1 eV band gap, and charge transfer excitations that are ~0.4 eV higher than those of the rhombohedral counterpart. We interpret these results in terms of structural strain and local symmetry breaking.

Permittivity And Permeability Of Fe(Tb) Nanoparticles And Their Microwave Absorption In The 2–18 Ghz Range, Z. Han, D. Li, M. Tong, X. Wei, Ralph Skomski, W. Liu, Z. D. Zhang, David J. Sellmyer

Ralph Skomski Publications

The permittivity and permeability of the Tb-doped and undoped Fe core-shell nanoparticles were investigated for frequencies from 2 to 18 GHz. The particles were synthesized by arc discharge and contain some oxygen, probably in the form of Fe₂O₃, Fe₃O₄, and Tb₂O₃, whereas the core material is Fe. Both the electromagnetic materials constants and the morphology of the Fe nanoparticles are changed by Tb addition, which gives rise to the shifts to higher frequencies and thinner thicknesses of the maximum microwave absorption in the Tb-doped Fe nanoparticles.

Structural, Magnetic And Magneto-Transport Properties Of Pt-Alloyed Mnbi Thin Films, Parashu Kharel, Ralph Skomski, Roger D. Kirby, David J. Sellmyer

Ralph Skomski Publications

The structural, magnetic and magneto-transport properties of highly c-axis oriented Mn_55−xPt_xBi₄₅ (x=0, 1.5, 3, and 4.5) thin films have been investigated. The coercivity of the Pt-alloyed thin films increases and the saturation magnetization decreases as the Pt concentration increases. The anisotropy field H_o increases as a function of Pt concentration, too but the coercivity increases more rapidly than the anisotropy field. This indicates an enhanced domain-wall pinning, caused by increased interstitial disorder due to the occupancy of regular Mn sites by Pt. The same mechanism explains the reduced magnetization. All samples exhibit a large …

Magnetism Of Core-Shell Ti:Tio Nanoparticles, Xiaohui Wei, Ralph Skomski, Balamurugan Balasubramanian, David J. Sellmyer

Ralph Skomski Publications

Ti nanoparticles were produced using a cluster-deposition method. Ti:TiO core-shell structures were fabricated by partially oxidizing the surface of the Ti nanoparticles produced by a cluster-deposition system via multistep annealing at 250 °C in oxygen. X-ray diffraction and transmission-electron microscopy studies reveal an increase in the thickness of the TiO shell with increasing annealing time. The magnetic moment and the coercivity of the core-shell nanoparticles increase with the TiO shell thickness, which is consistent with homogenous bulk defects in TiO. The core-shell nanoparticles display an abnormal hysteresis loop, which probably reflects a combination of antiferromagnetic exchange and magnetocrystalline anisotropy.

Magnetic Antiphase Domains In Co/Ru/Co Trilayers, Zhen Li, Ralph Skomski, Steven A. Michalski, Lanping Yue, Roger D. Kirby

Ralph Skomski Publications

Ultrathin Co/Ru/Co trilayers are investigated experimentally by magnetization curves and magnetic-force microscopy (MFM). Emphasis is on the domain-wall fine structure of antiphase domain walls in the films. The trilayers are produced by sputtering and consist of two Co layers of equal thickness (5 nm), exchange-coupled through a Ru layer of variable thickness. The sign and magnitude of the interlayer exchange are tuned by the thickness of the Ru interlayer. The exchange and its distribution are investigated by measurements of the static magnetization curves. For a Ru thickness of 0.4 nm, the exchange is predominantly antiferromagnetic and the MFM images show …

Interstitial-Nitrogen Effect On Phase Transition And Magnetocaloric Effect In Mn(As,Si) (Invited), W. B. Cui, X. K. Lv, F. Yang, Ralph Skomski, Y. Yu, X. G. Zhao, W. Liu, Z.D. Zhang

Ralph Skomski Publications

The effect of interstitial nitrogen on the phase transition and magnetocaloric behavior of MnAs_1−xSi_xN_δ (x=0.03, 0.06, and 0.09) is investigated. The interstitial nitrogen atoms cause the step-scanned x-ray diffraction peaks to shift toward lower angles and lower the Curie temperature, whereas silicon addition increases the Curie temperature to near room temperature. The thermal hysteresis is reduced to nearly 0 in MnAs_1−xSi_xN_δ, which is beneficial to practical applications. For a field change of 5 T, the largest magnetic entropy change and refrigerant capacity are 14.6 J kg⁻¹ K^{−1 …}

Bioturbation, Habitat Partitioning, And Tiering In Tropical Intertidal Callianassid Mounds: An Example From The Bahamas, H. Allen Curran

Geosciences: Faculty Publications

Abstract from 2010 Workshop on Crustacean Bioturbation — Fossil and Recent held in Lepe, Spain.

Editors: Jordi M. deGibert, Fernando Muñiz, Eduardo Mayoral, Zain Belaústegui

Troubleshooting With Surveys, Sandra Pereira

ECU Research Week

This presentation discusses ways to identify and avoid the problems commonly encountered in draft surveys.

Principal Component Analysis And Biochemical Characterization Of Protein And Starch Reveal Primary Targets For Improving Sorghum Grain, Joshua H. Wong, D. B. Marx, Jeff D. Wilson, Bob B. Buchanan, Peggy G. Lemaux, Jeffrey F. Pedersen

Department of Statistics: Faculty Publications

Limited progress has been made on genetic improvement of the digestibility of sorghum grain because of variability among different varieties. In this study, we applied multiple techniques to assess digestibility of grain from 18 sorghum lines to identify major components responsible for variability. We also identified storage proteins and enzymes as potential targets for genetic modification to improve digestibility. Results from principal component analysis revealed that content of amylose and total starch, together with protein digestibility (PD), accounted for 94% of variation in digestibility. Control of amylose content is understood and manageable. Up-regulation of genes associated with starch accumulation is …

Reference Priors For Exponential Families With Increasing Dimension, Bertrand S. Clarke, Subhashis Ghosal

Department of Statistics: Faculty Publications

In this article, we establish the asymptotic normality of the posterior distribution for the natural parameter in an exponential family based on independent and identically distributed data. The mode of convergence is expected Kullback-Leibler distance and the number of parameters p is increasing with the sample size n. Using this, we give an asymptotic expansion of the Shannon mutual information valid when p = pn increases at a sufficiently slow rate. The second term in the asymptotic expansion is the largest term that depends on the prior and can be optimized to give Jeffreys’ prior as the reference prior in …

Desiderata For A Predictive Theory Of Statistics, Bertrand Clarke

Department of Statistics: Faculty Publications

In many contexts the predictive validation of models or their associated prediction strategies is of greater importance than model identification which may be practically impossible. This is particularly so in fields involving complex or high dimensional data where model selection, or more generally predictor selection is the main focus of effort. This paper suggests a unified treatment for predictive analyses based on six 'desiderata'. These desiderata are an effort to clarify what criteria a good predictive theory of statistics should satisfy.

Generalized Fourier-Feynman Transforms, Convolution Products, And First Variations On Function Space, Seung Jun Chang, Jae Gil Choi, David Skough

Department of Mathematics: Faculty Publications

In this paper we examine the various relationships that exist among the first variation, the convolution product and the Fourier-Feynman transform for functionals of the form F(x) = f((α₁, x), . . . , (α_n, x)) with x in a very general function space C_a,b[0,T].

Assessing North American Influenza Dynamics With Hierarchical Spatio-Temporal Models, Jessica Anderson

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

We present a general statistical modeling framework to characterize continental-level influenza dynamics in the United States for the purposes of examining state-level epidemiological sources and sinks. The methods we describe depend directly on state-level influenza data that are updated weekly and available on the internet. Advances in search engine query analysis have provided powerful new tools for collecting epidemiological data and, when used in conjunction with sophisticated statistical models, allow for the identification and quantification of the flow of influenza across the continental United States. Our proposed methods, when conditioned on this comprehensive search query product, can provide unprecedented scientific …

A Comparison Of Prediction Methods Of Functional Autoregressive Time Series, Devin Didericksen

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Functional data analysis (FDA) is a relatively new branch of statistics that has seen a lot of expansion recently. With the advent of computer processing power and more efficient software packages we have entered the beginning stages of applying FDA methodology and techniques to data. Part of this undertaking should include an empirical assessment of the effectiveness of some of the tools of FDA, which are sound on theoretical grounds. In a small way, this project helps advance this objective.

This work begins by introducing FDA, scalar prediction techniques, and the functional autoregressive model of order one - FAR(1). Two …

Simulating Power For One-Way Anova By Using Non-Normal Error Distributions, Caixia Xu

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Usually we assume that the distribution of the additive errors in a one-way ANOVA linear model is normal. However, exceptions to this assumption about the error distribution may exist. In such cases, we might consider non-normal error distributions, but proceed with the "usual" ANOVA F-test analyses. This study focuses on simulating power for one-way ANOVA when using non-normal error distributions.

Redtnet: A Network Model For Strategy Games, Philip Hingston, Mike Preuss, Daniel Spierling

Research outputs pre 2011

In this work, we develop a simple, graph-based framework, RedTNet, for computational modeling of strategy games and simulations. The framework applies the concept of red teaming as a means by which to explore alternative strategies. We show how the model supports computer-based red teaming in several applications: realtime strategy games and critical infrastructure protection, using an evolutionary algorithm to automatically detect good and often surprising strategies.

Light Reductions Drive Macroinvertebrate Changes In Amphibolis Griffithii Seagrass Habitat, Adam Gartner, Paul S. Lavery, Kathryn Mcmahon, Anne Brearley, Helen Barwick

Research outputs pre 2011

Numerous anthropogenic activities can significantly reduce the amount of light reaching seagrass habitats. Typically these result in morphological and physiological changes to the plant and associated algal epiphytes. However, the flow-on effects to seagrass-dependent fauna induced by these disturbances has yet to be examined. This study investigated the effects of different light reduction intensity (high: ~92% reduction; moderate: ~84% reduction), duration (3, 6 and 9 mo) and timing (post-winter and post-summer) on the density and biomass of macroinvertebrate epifauna within an Amphibolis griffithii seagrass ecosystem (Western Australia). There were generally lower epifauna densities and biomass within shaded seagrass plots. When …

Android Forensics: Simplifying Cell Phone Examinations, Jeff Lessard, Gary Kessler

Research outputs pre 2011

It is hardly appropriate to call the devices many use to receive the occasional phone call a telephone any more. The capability of these devices is growing, as is the number of people utilizing them. By the end of 2009, 46.3% of mobile phones in use in the United States were reported to be smart phones (AdMob, 2010). With the increased availability of these powerful devices, there is also a potential increase for criminals to use this technology as well. Criminals could use smart phones for a number of activities such as committing fraud over e-mail, harassment through text messages, …

How Do You Make Information Security User Friendly?, Andrew Jones

Research outputs pre 2011

This article explores the past and the present situation, outlines a new approach, and presents conclusions.

Autonomous Bee Colony Optimization For Multi-Objective Function, F Zeng, James Decraene, Malcolm Low, Philip Hingston, C Wentong, Z Suiping, M Chandramohan

Research outputs pre 2011

An Autonomous Bee Colony Optimization (A-BCO) algorithm for solving multi-objective numerical problems is proposed. In contrast with previous Bee Colony algorithms, A-BCO utilizes a diversity-based performance metric to dynamically assess the archive set. This assessment is employed to adapt the bee colony structures and flying patterns. This self-adaptation feature is introduced to optimize the balance between exploration and exploitation during the search process. Moreover, the total number of search iterations is also determined/optimized by A-BCO, according to user pre-specified conditions, during the search process. We evaluate A-BCO upon numerical benchmark problems and the experimental results demonstrate the effectiveness and robustness …

A New Design For A Turing Test For Bots, Philip Hingston

Research outputs pre 2011

Interesting, human-like opponents add to the entertainment value of a video game, and creating such opponents is a difficult challenge for programmers. Can artificial intelligence and computational intelligence provide the means to convincingly simulate a human opponent? Or are simple programming tricks and deceptions more effective? To answer these questions, the author designed and organised a game bot programming competition, the BotPrize, in which competitors submit bots that try to pass a “Turing Test for Bots”. In this paper, we describe a new design for the competition, which will make it simpler to run, and, we hope, open up new …

An Analysis Of Information Security Awareness Within Home And Work Environments, Shuhaili Talib, Nathan Clarke, Steven Furnell

Research outputs pre 2011

As technology such as the Internet, computers and mobile devices become ubiquitous throughout society, the need to ensure our information remains secure is imperative. Unfortunately, it has long been understood that good security cannot be achieved through technical means alone and a solid understanding of the issues and how to protect yourself is required from users. Whilst many initiatives, programs and strategies have been proposed to improve the level of information security awareness, most have been directed at organizations, with a few national programs focused upon home users. Given people's use of technology is primarily focused upon those two areas: …