Digital Commons Network^™

From The Field: Field Searches Versus Vaginal Implant Translocating Elk Calves, Nathan W. Seward, David S. Maehr, Jonathan W. Gassett, John J. Cox, Jeffrey L. Larkin

United States Department of Agriculture Wildlife Services: Staff Publications

We compared the utility of vaginal implant transmitters (VITs) and field searches for locating elk (Cervus elaphus) calves in southeastern Kentucky during the spring of 2001. Retention of VITs among 40 adult females ranged from 1–276 days (x - =61.6±8.4 [SE] days). Approximately half of the transmitters (n=19) were expelled prematurely or malfunctioned. Two of 37 (5%) transmitters in translocated females performed as designed and led to calf capture. We captured more calves (n=9 in 2001; n=16 in 2002) by searching areas where elk exhibited parturition behavior. We suggest that manufacturers refine the current VIT design to increase its application …

Foraging Behavior And Monetary Impact Of Wading Birds At Arkansas Baitfish Farms, Scott J. Werner, J. Brett Harrel, David E. Wooten

United States Department of Agriculture Wildlife Services: Staff Publications

WP rnnrlurted fnraging ob,ervations, food habits studie~, and producer aurveys to determine the foraging behavior and monetary impact of great blue herons Ardca hr.rodia5, great egrets A. alba, and little blue heron5 E m t r a cnurulua lora-g in-e at Arkansas haiffish farms. Although great egrets captured most baitfishlminute, captureslstrike were nearlj identical among the three wadine bird snecies. American eizzard shad Dorosoma crordinnum. eoldfish Carossius nuratul. D - . - and giant water bugs Hemiplera: Beloston~atidaew ere collected from the gastro-intestinal tract of grent blue herons. Only golden shiners ,Votrrni~onuc,~ry soleucur and goldfish were found in great egrets. …

Weak Solutions To The Cauchy Problem Of A Semilinear Wave Equation With Damping And Source Terms, Petronela Radu

Department of Mathematics: Faculty Publications

In this paper we prove local existence of weak solutions for a semilinear wave equation with power-like source and dissipative terms on the entire space ℝⁿ. The main theorem gives an alternative proof of the local in time existence result due to J. Serrin, G. Todorova and E. Vitillaro, and also some extension to their work. In particular, our method shows that sources that are not locally Lipschitz in L² can be controlled without any damping at all. If the semilinearity involving the displacement has a “good” sign, we obtain global existence of solutions.

Temperature Dependence Of The Magnetism In Fe/Cu(001), Axel Enders, D. Repetto, D. Peterka, Klaus Kern

Axel Enders Publications

The correlation between morphology and magnetism of ultrathin epitaxial films is investigated by a combined study of variable temperature scanning tunneling microscopy, magneto-optical Kerr effect measurements, and Kerr microscopy under ultrahigh vacuum condition. The magnetization reversal of the films was studied as a function of temperature by imaging the propagation of Bloch domain walls in situ. It is demonstrated on the example of fcc Fe films grown at 120 K on Cu(001) that changes in the morphology of the films during annealing are directly reflected in modified magnetic properties. Competing pinning mechanisms for the domain wall propagation are identified. The …

Experimental Studies Of Light Propagation And Storage In Warm Atomic Gases, H. Gao, Mark A. Rosenberry, J. Wang, Herman Batelaan

Department of Physics and Astronomy: Faculty Publications

We report on an experimental study of slow pulse propagation and polarization storage of light in an atomic vapour for pulse durations ranging from several μs to 100 μs, for non-zero magnetic fields, for temperatures ranging from 65 to 90 °C and for two different rubidium isotopes. The results confirm the presence of the electromagnetically induced transparency window as predicted by Lukin (1997 Phys. Rev. Lett. 79 2959). We show that time-dependent optical rotation can mask the storage of light signal, and demonstrate storage of light for the ⁸⁵Rb isotope.

Electron Diffraction From Free-Standing, Metal-Coated Transmission Gratings, Glen Gronniger, Brett E. Barwick, Herman Batelaan, Tim Savas, David E. Pritchard, Alex Cronin

Department of Physics and Astronomy: Faculty Publications

Electron diffraction from a free-standing nanofabricated transmission grating was demonstrated, with energies ranging from 125 eV to 25 keV. Observation of 21 diffraction orders highlights the quality of the gratings. The image charge potential due to one electron was measured by rotating the grating. These gratings may pave the way to low-energy electron interferometry.

Dielectric Properties And Maxwell-Wagner Relaxation Of Xompounds Acu3Ti4O12 (A=Ca,Bi2/3,Y2/3,La2/3), Jianjun Liu, Chun-Gang Duan, Wai-Ning Mei, R. W. Smith, John R. Hardy

John R. Hardy Papers

We have studied the frequency and temperature dependences of permittivity and impedance of the compounds ACu₃Ti₄O₁₂ (A=Ca, Bi_2/3, Y_2/3, Las2/3) in the ranges of 10⁻¹–10⁶ Hz and −150–200 °C. All compounds investigated display similar dielectric properties. Specifically, they all have a Debye-like relaxation and their dielectric constants are independent of frequency and temperature over a wide range. They all have two electrical responses in impedance formalism, indicating that there are two distinct contributions. We attribute them to grains and grain boundaries in the ceramic samples and explain the …

Phase Transition In Single Crystal Cs2Nb4O11, Jianjun Liu, E. P. Kharitonova, Chun-Gang Duan, Wai-Ning Mei, R. W. Smith, John R. Hardy

John R. Hardy Papers

We studied temperature dependence of complex capacitance, impedance, and polarized Raman spectra of single crystal Cs₂Nb₄O₁₁. First, we observed a sharp λ-shaped peak at 165 °C in the complex capacitance, then found drastic changes in the Raman spectra in the same temperature range. Utilizing the pseudosymmetry search of structure space group, we attributed the observed anomalies to a structural change from the room temperature orthorhombic Pnn2 to another orthorhombic Imm2. We also measured room temperature polarized Raman spectra in different symmetries of normal vibrations and assigned high wavenumber Raman bands to the …

Examining The Screening Limit Of Field Effect Devices Via The Metal–Insulator Transition, X. Hong, A. Posadas, C. H. Ahn

Xia Hong Publications

The electronic screening length, the distance over which an electric field is attenuated in a material, imposes a lower physical bound on the lateral size scaling of semiconductor field effect devices. Alternatives will be needed to achieve devices whose characteristic dimensions approach a nanometer. In this work, we demonstrate the atomic-scale nature of screening at high electron densities, using the polarization field of a ferroelectric oxide, Pb(Zr,Ti)O₃, to electrostatically modulate the metallicity of ultrathin manganite La_1−xSr_xMnO₃ (LSMO) films near the metal-insulator transition. Within the screening length, the transport characteristics of LSMO vary sharply …

Magnetic Moments And Adiabatic Magnetization Of Free Cobalt Clusters, Xiaoshan Xu, Shuangye Yin, Ramiro Moro, Walt A. De Heer

Xiaoshan Xu Papers

Magnetizations and magnetic moments of free cobalt clusters CoN (12< N <200) in a cryogenic (25 K ≤ T ≤ 100 K) molecular beam were determined from Stern-Gerlach deflections. All clusters preferentially deflect in the direction of the increasing field and the average magnetization resembles the Langevin function for all cluster sizes even at low temperatures. We demonstrate in the avoided crossing model that the average magnetization may result from adiabatic processes of rotating and vibrating clusters in the magnetic field and that spin relaxation is not involved. This resolves a longstanding problem in the interpretation of cluster beam deflection experiments with implications for nanomagnetic systems in …

A Multilocus Population Genetic Survey Of The Greater Sage-Grouse Across Their Range, S. J. Oyler-Mccance, S.E. Taylor, T. W. Quinn

United States Geological Survey: Staff Publications

The distribution and abundance of the greater sage-grouse (Centrocercus urophasianus) have declined dramatically, and as a result the species has become the focus of conservation efforts. We conducted a range-wide genetic survey of the species which included 46 populations and over 1000 individuals using both mitochondria1 sequence data and data from seven nuclear microsatellites. Nested clade and STRUCTURE analyses revealed that, in general, the greater sage-grouse populations follow an isolation-by-distance model of restricted gene flow. This suggests that movements of the greater sage-grouse are typically among neighboring populations and not across the species, range. This may have important …

Transport Of Chemical And Microbial Compounds From Known Wastewater Discharges: Potential For Use As Indicators Of Human Fecal Contamination, Susan Glassmeyer, Edward Furlong, Dana Kolpin, Jeffrey Cahill, Steven Zaugg, Stephen Werner, Michael Meyer, David Kryak

United States Geological Survey: Staff Publications

The quality of drinking and recreational water is currently (2005) determined using indicator bacteria. However, the culture tests used to analyze for these bacteria require a long time to complete and do not discriminate between human and animal fecal material sources. One complementary approach is to use chemicals found in human wastewater, which would have the advantages of (1) potentially shorter analysis times than the bacterial culture tests and (2) being selected for human-source specificity. At 10 locations, water samples were collected upstream and at two successive points downstream from a waste-waster treatment plant (WWTP); a treated effluent sample was …

West Nile Virus Infection In Farmed American Alligators (Alligator Mississippiensis) In Florida, Elliott R. Jacobson, Pamela E. Ginn, J. Mitchell Troutman, Lisa Farina, Lillian Stark, Kaci Klenk, Kristen L. Burkhalter, Nicholas Komar

United States Department of Agriculture Wildlife Services: Staff Publications

No abstract provided.

Serologic Evidence Of Exposure Of Wild Mammals To Flaviviruses In The Central And Eastern United States, J. Jeffrey Root, Jeffrey S. Hall, Robert G. Mclean, Nicole L. Marlenee, Barry J. Beaty, Justin Gansowski, Larry Clark

United States Department of Agriculture Wildlife Services: Staff Publications

Serosurveys were conducted to obtain flavivirus and West Nile virus (WNV) seroprevalence data from mammals. Sera from 513 small- and medium-sized mammals collected during late summer and fall 2003 from Colorado, Louisiana, New York, Ohio, and Pennsylvania were screened for flavivirus-specific antibodies. Sera samples containing antibody to flaviviruses were screened for WNV-specific antibodies by epitope-blocking enzyme-linked immunosorbent assays and confirmed with plaque reduction neutralization tests. Prevalence of WNV antibodies among study sites ranged from 0% to 42.8% among the mammal communities sampled. High prevalence rates for WNV were noted among raccoons (100%, with a very small sample size, N = …

Climate Change And Amphibians, P.S. Corn

United States Geological Survey: Staff Publications

Amphibian life histories are exceedingly sensitive to temperature and precipitation, and there is good evidence that recent climate change has already resulted in a shift to breeding earlier in the year for some species. There are also suggestions that the recent increase in the occurrence of El Niño events has caused declines of anurans in Central America and is linked to elevated mortality of amphibian embryos in the northwestern United States. However, evidence linking amphibian declines in Central America to climate relies solely on correlations, and the mechanisms underlying the declines are not understood. Connections between embryo mortality and declines …

An Evaluation Of Weather And Disease As Causes Of Decline In Two Populations Of Boreal Toads, Rick D. Scherer, Erin Muths, Barry R. Noon, Paul Stephen Corn

United States Geological Survey: Staff Publications

Two populations of boreal toads (Bufo boreas) experienced drastic declines in abundance in the late 1990s. Evidence supported the hypothesis of disease (the chytrid fungus, Batrachochytrium dendrobatidis) as the cause of these declines. but other hypotheses had not been evaluated. We used an 11-year capture-recapture data set to evaluate weather and disease as causes of these declines. We developed sets of mathematical models that reflected hypothesized relationships between several weather variables and annual survival rates of adult males in these populations. In addition, models that reflected the possibility that the declines were caused by an introduced fungus …

Amphibian Research And Monitoring Initiative (Armi): A Successful Start To A National Program In The United States, Erin Muths, Robin E. Jung, Larissa L. Bailey, Michael J. Adams, P. Stephen Corn, C. Kenneth Dodd Jr., Gary M. Fellers, Walter J. Sadinski, Cecil R. Schwalbe, Susan C. Walls, Robert N. Fisher, Alisa L. Gallant, William A. Battaglin, D. Earl Green

United States Geological Survey: Staff Publications

Most research to assess amphibian declines has focused on local-scale projects on one or a few species. The Amphibian Research and Monitoring Initiative (ARMI) is a national program in the United States mandated by congressional directive and implemented by the U.S. Department of the Interior (specifically the U.S. Geological Survey, USGS). Program goals are to monitor changes in populations of amphibians across U.S. Department of the Interior lands and to address research questions related to amphibian declines using a hierarchical framework of base-, mid- and apex-level monitoring sites. ARMI is currently monitoring 83 amphibian species (29% of species in the …

Processing Of Yield Map Data, J. L. Ping, Achim R. Dobermann

Department of Agronomy and Horticulture: Faculty Publications

Yield maps reflect systematic and random sources of yield variation as well as numerous errors caused by the harvest and mapping procedures used. A general framework for processing of multi-year yield map data was developed. Steps included (1) raw data screening, (2) standardization, (3) interpolation, (4) classification of multi-year yield maps, (5) post-classification spatial filtering to create spatially contiguous yield classes, and (6) statistical evaluation of classification results. The techniques developed allow more objective mapping of yield zones, which are an important data layer in algorithms for prescribing variable rates of production inputs.

Marketing Locally Produced Foods: Consumer And Farmer Opinions In Washington County, Nebraska, Mindi L. Schneider, Charles A. Francis

Department of Agronomy and Horticulture: Faculty Publications

Local food system potentials were studied in Washington County, Nebraska, United States. As a departure from most studies of locally based systems, farmers were surveyed in addition to consumers for potential participation. Data about the current food system and opinions and preferences for local production, marketing, and purchasing of food were collected using self-administered mail questionnaires. The response rate was 35% for the farmer survey and 37% for the consumer survey. Results indicated that, on the farming side of the food system, conventional corn and soybean production and marketing predominated in Washington County, and farmer interest in producing for local …

Use Of The Hybrid-Maize Model To Improve Management Decisions, Achim R. Dobermann, Haishun Yang, Daniel T. Walters, Kenneth G. Cassman

Department of Agronomy and Horticulture: Faculty Publications

Yield potential and yield gaps

Basic structure of Hybrid-Maize

Model inputs

Model applications

Validation, uncertainties & future improvements

Leaf Radiative Properties And The Leaf Energy Budget, Timothy J. Arkebauer

Department of Agronomy and Horticulture: Faculty Publications

Leaf radiative properties are the physical properties of leaves that characterize radiant energy exchange with their surroundings. Radiant energy exchange is an important consideration in studies of plant function since, for example, absorption of photosynthetically active radiation (PAR) leads to the transformation of this energy into chemical energy via photosynthesis. Thus, plant productivity, and hence, agricultural production, ultimately depend on leaf radiative properties.

Leaf temperature is an additional, very important, parameter in intimate association with leaf radiant energy exchange. This association occurs since energy gained via radiation must be in balance with energy lost through various processes and energy loss …

Finite Element Modeling And Experimental Validation Of Cooling Rates Of Large Ready-To-Eat Meat Products In Small Meat-Processing Facilities, A. Amézquita, L. Wang, Curtis L. Weller

Department of Agricultural and Biological Systems Engineering: Faculty Publications

A two−dimensional axisymmetric transient heat conduction model was developed to simulate air chilling of large ready−to−eat meat products of ellipsoidal shape. A finite element scheme, using 1,600 linear triangular elements with 861 nodes, was implemented in Matlab 6.5 to solve the model. The model considered a variable initial temperature distribution and combined convective, radiative, and evaporative boundary conditions. Predicted values agreed well with experimental data collected in actual processing conditions. Validation of model performance resulted in maximum deviations of 2.54°C and 0.29% for temperature and weight loss histories, respectively. The maximum temperature deviation (2.54°C) occurred at the surface; however, for …

Modeling Of Bubble Growth Dynamics And Nonisothermal Expansion In Starch-Based Foams During Extrusion, Lijun Wang, Girish M. Ganjyal, David D. Jones, Curtis L. Weller, Milford Hanna

Department of Agricultural and Biological Systems Engineering: Faculty Publications

A mathematical model was developed to describe expansion phenomena in starch-based foams during extrusion. The model was divided into three parts to describe the microbubble growth dynamics, to couple bubble growth with extrudate expansion, and to describe the macrotransport phenomena in the extrudate, respectively. The differential equations involved in the model were solved by finite element schemes. For validating the model, the predicted radius, density, and residual moisture of final extrudate were compared with experimental data. Standard deviations between the predicted and experimental radius, density, and residual moisture of final extrudates were 16.7%, 11.2%, and 39.3%, respectively. The model was …

Modeling Sediment Trapping In A Vegetative Filter Accounting For Converging Overland Flow, M. J. Helmers, D. E. Eisenhauer, Thomas G. Franti, Michael G. Dosskey

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Vegetative filters (VF) are used to remove sediment and other pollutants from overland flow. When modeling the hydrology of VF, it is often assumed that overland flow is planar, but our research indicates that it can be two-dimensional with converging and diverging pathways. Our hypothesis is that flow convergence will negatively influence the sediment trapping capability of VF. The objectives were to develop a two-dimensional modeling approach for estimating sediment trapping in VF and to investigate the impact of converging overland flow on sediment trapping by VF. In this study, the performance of a VF that has field-scale flow path …

Bibliography Of Studies In Electron Transmission Spectroscopy, Paul Burrow

Paul Burrow Publications

A variety of techniques can be used to locate temporary negative ion states in atoms and molecules. One of the most efficient methods passes an electron beam through a gas cell and observes structure appearing in the attenuated “transmitted” electron current as a function of the electron energy. In 1971 L. Sanche and G.J. Schulz introduced a scheme whereby the derivative with respect to energy of the transmitted current was measured. Combining this with the trochoidal electron monochromator devised by A. Stamatovic and G.J. Schulz in 1968 produced a compact, sensitive and easily used apparatus for the detection of short-lived …

Dynamics Of Filament Formation In A Kerr Medium (With Erratum), Martin Centurion, Ye Pu, Mankei Tsang, Demetri Psaltis

Martin Centurion Publications

We have studied the large-scale beam breakup and filamentation of femtosecond pulses in a Kerr medium. We have experimentally monitored the formation of stable light filaments, conical emission, and interactions between filaments. Three major stages lead to the formation of stable light filaments: First the beam breaks up into a pattern of connected lines (constellation), then filaments form on the constellations, and finally the filaments release a fraction of their energy through conical emission. We observed a phase transition to a faster filamentation rate at the onset of conical emission. We attribute this to the interaction of conical emissions with …

Switching In One Monolayer Of The Ferroelectric Polymer, Vladimir Fridkin, A. Ievlev, K. Verkhovskaya, G. Vizdrik, S. Yudin, Stephen Ducharme

Stephen Ducharme Publications

The switching in one monolayer of ferroelectric vinylidene fluoride-trifluoroethylene copolymer P[VDF-TrFE] is observed. The kinetics of switching is well described by Landau- Khalatnikov (LK) equation.

The paper is devoted to the 75th anniversary of Prof. Lemanov’s birthday.

Investigation Of Ferroelectricity In Newly Synthesized Nitrile Polymer Systems, Matt Poulsen, Stephen Ducharme, Alexander V. Sorokin, Sahadeva Reddy, James M. Takacs, Y. Wen, Jihee Kim, Shireen Adenwalla

Stephen Ducharme Publications

The ferroelectric and piezoelectric properties of newly synthesized polymer systems have been studied. To date PVDF and its copolymers P(VDF-TrFE) have provided the bulk of the knowledge pertaining to ferroelectricity in polymers. Recently, ultrathin ferroelectric films of P(VDF-TrFE) 70:30 have been fabricated using the Langmuir-Blodgett technique [4]. In this study, various new polymers have been synthesized by chemically altering the PVDF structure. This alteration was performed in order to enhance the amphiphilic nature of the polymer and thus improve the LB film quality and control. Various chemical groups have been used to replace the electropositive hydrogen and electronegative fluorine found …

Are Dispositions Causally Relevant?, Jennifer Mckitrick

Department of Philosophy: Faculty Publications

To determine whether dispositions are causally relevant, we have to get clear about what causal relevance is. Several characteristics of causal relevance have been suggested, including Explanatory Power, Counterfactual Dependence, Lawfulness, Exclusion, Independence, and Minimal Sufficiency. Different accounts will yield different answers about the causal relevance of dispositions. However, accounts of causal relevance that are the most plausible, for independent reasons, render the verdict that dispositions are causally relevant.

Book Review: Gideon Yaffee, Manifest Activity: Thomas Reid’S Theory Of Action, Jennifer Mckitrick

Department of Philosophy: Faculty Publications

Gideon Yaffee’s Manifest Activity is an important contribution to both the studies of Thomas Reid’s views and action theory. Reid is known as an early advocate of an agent-causal view of free will; more recent advocates include Roderick Chisholm. Manifest Activity is a well-appreciated effort at bringing Reid’s particular version of agent-causalism and his arguments for it into the contemporary discussion. Manifest Activity should be of interest to Reid scholars, action theorists, and anyone who wants to explore a focused, critical analysis of a fascinating thinker.

Yaffee’s writing is clear and readable, yet rigorous and detailed. Yaffee’s aim in each …