Physical Sciences and Mathematics Commons^™

Nanocomposite Copt:C Films For Extremely High-Density Recording, M. Yu, Yi Liu, A. Moser, D. Weller, David J. Sellmyer

David Sellmyer Publications

Nanocomposite CoPt:C films were investigated as potential media for extremely high-density recording. An annealing temperature of over 600 °C is necessary to form nanocomposite CoPt:C films consisting of C matrix and fct CoPt nanocrystallites with grain sizes of 8–20 nm and coercivities of 3–12 kOe. Coercivity and grain size increase with increasing annealing temperature and decreasing C concentration and they are insensitive to film thickness. The average activation volumes are about 0.9×10^-18 cm³. The properties of these nanocomposite CoPt:C films can be tailored to satisfy the thermal stability, coercivity, and media noise requirements for extremely high-density recording.

A Patching Model For Surface Tension Of Spherical Droplet And Tolman Length. Ii, T.V. Bykov, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

In the framework of density functional theory (DFT), two patching models for the density profile of spherical liquid droplet are developed. The patching is based on analytical expressions of the asymptote of the density profiles. The first model leads to analytic expressions of the Tolman length and the effective rigidity constant, from which the temperature dependence of the Tolman length and effective rigidity constant can be determined. The second model is developed particularly for small spherical droplets, from which the dependence of chemical potential and the surface tension of the droplet on the radius are obtained. The results are compared …

Langmuir Monolayers As Disordered Solids: Disorder And Elastic Fluctuations In Mesophases , Tadeusz Luty, Craig J. Eckhardt, Jacques Lefebvre

Craig J. Eckhardt Publications

Ordering in Langmuir monolayer mesophases is examined using an approach based on the elastic theory of crystals. Molecular tails are modeled as ‘‘defects’’ grafted onto a two-dimensional elastic medium and are characterized by elastic dipoles. It is assumed that disorder in the parent, LS, phase is due to competition between local (within a domain) and global (hexagonal arrangement of domains) structure. By treating the LS phase as a mixture of rectangular and/or oblique domains (rectangular and/or oblique defects within the two-dimensional elastic medium), density fluctuations due to elastic interactions between domains are analyzed. The correlation function for the elastic dipoles …

Local And Landscape Factors Affecting Nest Site Selection And Nest Success Of Burrowing Owls In Western Nebraska, Rebecca T. Ekstein

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

No abstract provided.

Ecology Of Elk In Northwestern Nebraska: Demographics, Effects Of Human Disturbance, And Characteristics Of Calving Habitat, Bruce A. Stillings

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

No abstract provided.

Water Current, Volume 31, No. 6, December 1999

Water Current Newsletter

Conference to Develop a Management Agenda for Nebraska's Water Future
From the Director: We Have a Long Way, But We Need to Go Further; Water Center Recognized as "Groundwater Guardian" Partner
NU Research Faculty Voice Desires for Strong Water Center Leadership
Citizen Stewards of the Pines and Plains
Fourth Water Tabloid Now Available from NU
Water News Briefs
Sixth Annual Undergrad Research Conference
Publications
National Geographic Society Awarding Science Grants
Call for Papers: Spatial Symposium in Reno, Nevada
Call for Papers: 11th Platte River Basin Symposium
Cooperation and Tension: The History, Reality and Future of Nebraska's Interstate Agreements

Experiments To Assess The Cost-Benefits Of Test-Suite Reduction, Gregg Rothermel, Mary Jean Harrold, Jeffery Von Ronne, Christie Hang, Jeffery Ostrin

CSE Technical Reports

Test-suite reduction techniques attempt to reduce the cost of saving and reusing test cases during software maintenance by eliminating redundant test cases from test suites. A potential drawback of these techniques is that in reducing a test suite they might reduce the ability of that test suite to reveal faults in the software. Previous studies suggested that test-suite reduction techniques can reduce test suite size without significantly reducing the fault-detection capabilities of test suites. To further investigate this issue we performed experiments in which we examined the costs and benefits of reducing test suites of various sizes for several programs …

La Gestion De La Faune Aux Aeroports, Edward C. Cleary , Richard A. Dolbeer

Other Bird Strike and Aviation Materials

L’homme a toujours ete intrigue et inspire par la beaute des oiseaux et leur capacite de voler. Mais si les oiseaux ont colonise le ciel il y a quelque 150 millions d’annees, nous ne partageons leur espace aerien que depuis cent ans. Helas, ce partage forcement simultane est source de collisions. Certes, les oiseaux ne sont pas les seuls problemes des pilotes.

Measurement Of The B0B̅0 Oscillation Frequency Using L-D*+ Pairs And Lepton Flavor Tags, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

The oscillation frequency Δm_d of B⁰B̅⁰ mixing is measured using the partially reconstructed semileptonic decay B̅⁰→l^- ν̅ D^*+X. The data sample was collected with the CDF detector at the Fermilab Tevatron collider during 1992–1995 by triggering on the existence of two lepton candidates in an event, and corresponds to about 110 pb^-1 of p̅p collisions at √s =1.8 TeV. We estimate the proper decay time of the B̅⁰ meson from the measured decay length and reconstructed momentum of the l^-D^*+ system. The charge of …

Molecular-Dynamics Study Of Phase Transitions In Alkali Azides, M. M. Ossowski, John R. Hardy, R. W. Smith

John R. Hardy Papers

An account is presented of our studies of the order-disorder phase transitions in KN₃, RbN₃, and CsN₃. These are based on parameter-free interionic potentials based on the Gordon-Kim modified electron-gas formalism extended to molecular ions. We performed static structural relaxations and supercell molecular dynamics and predicted with reasonable accuracy the temperatures for the onset of the transitions. In particular, we address the question of how the N₃^- ions reorient to yield the transitions. We found the existence of NaCl-type high-temperature phases in disordered KN₃ and RbN₃ and argue that this …

The Probe, Issue 207 – December 1999

The Probe: Newsletter of the National Animal Damage Control Association

NADCA: A Proud History, A New Future -- Robert H. Schmidt, President, NADCA
Position Announcement: WILDLIFE ECOLOGIST - Urban Wildlife & Urban-Human Conflict Management Illinois Natural History Survey, Urbana-Champaign, IL
In Memoriam: Guy R. Hodge
Personnel Changes in USDA Wildlife Services: Two new State Directors
Book review: "Wildlife of the New Millennium: A Field Guide" by Buck Peterson. Published by Longstreet Press, Marietta, Georgia 1999. (152 pages, illustrated. $11.95) ISBN 1-56352-546-1
Euthanasia Chamber Available from Pioneer Wildlife Control of Westwood, MA

Abstracts from the 6th Annual Conference of The Wildlife Society - September 1999, Austin, TX
Public health significance of …

Wildlife-Caused Losses For Producers Of Channel Catfish Ictalurus Punctatus In 1996, Alice P. Wywialowski

USDA Wildlife Services: Staff Publications

The National Agricultural Statistics Service surveyed by telephone and mail in January and February 1997 all known producers of channel catfish Ictalurus punctatus to acquire current information about wildlife-caused losses in calendar year 1996. Many producers tried to prevent wildlife-caused losses of their catfish by shooting (57%), vehicle patrol (55%), or frightening (36%), at an estimated cost of >$5 million. Yet, 69% of catfish produces cited some wildlife-caused losses. Birds were most frequently cited as a cause of losses, and double-crested cormorants Phalacrocorax auritus was the species cited most frequently (53%). The next most frequently cited bids were herons Ardea …

Detailed Dynamics Of Electron Beams Self-Trapped And Accelerated In A Self-Modulated Laser Wakefield, Shouyuan Chen, M. Krishnan, Anatoly Maksimchuk, R. Wagner, Donald P. Umstadter

Donald Umstadter Publications

The electron beam generated in a self-modulated laser-wakefield accelerator is characterized in detail. A transverse normalized emittance of 0.06 π mm mrad, the lowest ever for an electron injector, was measured for 2 MeV electrons. The electron beam was observed to have a multicomponent beam profile and energy distribution. The latter also undergoes discrete transitions as the laser power or plasma density is varied. In addition, dark spots that form regular modes were observed in the electron beam profile. These features are explained by analysis and test particle simulations of electron dynamics during acceleration in a three-dimensional plasma wakefield.

Photodetachment Of He- In The Vicinity Of The He* (N=3, 4, And 5) Thresholds, Chien-Nan Liu, Anthony F. Starace

Anthony F. Starace Publications

A comprehensive eigenchannel R-matrix study of photodetachment of He-(1 s2s2p ⁴P⁰ (1 ) is presented for the energy region of the Hesnl³l) thresholds, where 3<~n<~5. Over this energy region we present all partial cross sections which have been measured experimentally, including theoretical predictions (1 for the Hes3p ³P ( ) partial cross section, as well as energies and widths for all resonances, and identifications of all major ones. Near the Hen=3) thresholds, we predict two ⁴D^e resonances that to our knowledge have previously been neither predicted nor observed, and present results showing their effects on partial cross sections and photoelectron angular distributions; …

Estimating The Probability Of Severe Convective Storms: A Local Perspective For The Central And Northern Plains, Preston W. Leftwich Jr.

NOAA Technical Reports and Related Materials

Summary and Conclusions

A procedure to estimate probabilities of the occurrence of severe convective storms within local areas has been described. Probabilities were based on a simulated climatology and the relative frequency of severe convective events when a selected site was contained within an operational Outlook or Watch. Combined data from five local areas were used to develop a general model for local probabilities within the central and northern Plains region. Attachment of probabilities to specific products placed values within a framework familiar to both forecasters and "end-users." Application of results in an operational scenario demonstrated representative local probabilities and …

Reconnaissance Survey Of Lewis And Clark On The Missouri National Recreational River, Nebraska And South Dakota, Anne P. Diffendal, Gary E. Moulton, Michael Shambaugh-Miller, Robert F. Diffendal Jr.

School of Natural Resources: Faculty Publications

Part I
Lewis and Clark on the Middle Missouri by Gary E. Moulton
Appendix: Principal Sites and Events
Select Bibliography

Part II
Locating Lewis and Clark Sites
Site #1 Floyd's Bluff
Site #2 Gass's Election
Site #3 Ionia Volcano
Site #4 1804 Mouth of the Vermillion River
Site #5 Spirit Mound
Site #6 Shannon's Absence
Site #7 Calumet Bluff
Site #8 "Ancient Fortifications"
Site #9 Mouth of the Niobrara River
Site # 10 Old Baldy

Lattice-Stiffening Transition In Copolymer Films Of Vinylidene Fluoride (70%) With Trifluoroethylene (30%), C.N. Borca, Shireen Adenwalla, Jaewu Choi, P.T. Sprungerr, Stephen Ducharme, Lee Robertson, S.P. Palto, Jianglai Liu, Matt Poulsen, V.M. Fridkin, H. You, Peter A. Dowben

Peter Dowben Publications

We report the discovery of a compressibility phase transition at 160 K in crystalline copolymer films of vinylidene fluoride ( 70%) with trifluoroethylene ( 30%). This phase transition is distinct from the known bulk ferroelectric-paraelectric phase transition at 353 K and surface ferroelectric phase transition at 295 K. The new phase transition is characterized by an increase in the effective Debye temperature from 48 to 245 K along the 〈010〉 direction as the temperature falls below 160 K. This phase transition is evident in neutron scattering, x-ray diffraction, angle-resolved photoemission, and in the dipole active phonon modes in electron energy-loss …

Remote Sensing Of Photosynthetic-Light-Use Efficiency Of Boreal Forest, Caroline J. Nichol, Karl F. Huemmrich, T. Andrew Black, Paul G. Jarvis, Charles L. Walthall, John Grace, Forrest G. Hall

United States National Aeronautics and Space Administration: Publications

Using a helicopter-mounted portable spectroradiometer and continuous eddy covariance data we were able to evaluate the photochemical reflectance index (PRI) as an indicator of canopy photosynthetic light-use efficiency (LUE) in four boreal forest species during the Boreal Ecosystem Atmosphere experiment (BOREAS). PRI was calculated from narrow waveband reflectance data and correlated with LUE calculated from eddy covariance data. Significant linear correlations were found between PRI and LUE when the four species were grouped together and when divided into functional type: coniferous and deciduous. Data from the helicopter-mounted spectroradiometer were then averaged to represent data generated by the Airborne Visible Infrared …

Electron Injection By Dephasing Electrons With Laser Fields, E. Dodd, J.K. Kim, Donald P. Umstadter

Donald Umstadter Publications

The authors seek to review injection concepts for plasma based acceleration. It is shown that regardless of injection mechanism, resultant beams will be similar due to wave structure. Also, most schemes employ the same basic processes, namely the dephasing of electrons by laser fields, and can thus be analyzed with similar approaches.

Acceleration Of Electrons In A Self-Modulated Laser Wakefield, Shouyuan Chen, M. Krishnan, Anatoly Maksimchuk, Donald P. Umstadter

Donald Umstadter Publications

Acceleration of electrons in a self-modulated laser-wakefield is investigated. The generated electron beam is oberved to have a multi-component beam profile and its energy distribution undergoes discrete transitions as the conditions are varied. These features can be explained by simple simulations of electron propagation in a 3-D plasma wave.

Rkky Interactions Between Nanomagnets Of Arbitrary Shape, Ralph Skomski

Ralph Skomski Publications

The RKKY interaction between well-separated magnetic particles in a nonmagnetic metallic matrix is calculated. It turns out that the net interaction can be mapped onto an RKKY interaction between two point-like effective moments. The effective moments exhibit a strongly oscillating dependence on the particle's size, shape, and orientation, but their magnitudes are governed by scaling laws. As a rule, magnetostatic interactions tend to suppress the RKKY effect in particles larger than about 1 nm. Surface roughness leaves the effective-moment picture unaltered but tends to yield a moderate reduction of the effective moments. The results are discussed in the context of …

Selective Adsorption Of Metallocenes On Clean And Chemically Modified Si(111) Surfaces, J.-L. Lin, H. Rauscher, A. Kirakosian, F.J. Himpsel, Peter A. Dowben

Peter Dowben Publications

Metallocene adsorption on clean Si(111) and CaF₂/CaF₁/Si(111) substrates has been investigated with scanning tunneling microscopy. The surface chemical composition is found to strongly change the adsorption site selectivity, leading to an enhanced edge selectivity on modified substrates. Templates with well-defined local chemical reactivity have been created via self-assembly. The selective adsorption of metallocenes on such tailored substrates facilitates patterning ordered arrays of magnetic nanowires and stripes on the single digit nanometer scale. ©1999 American Institute of Physics.

Structural And Magnetic Properties Of Fept:Sio2 Granular Thin Films, C.P. Luo, David J. Sellmyer

David Sellmyer Publications

Nanocomposite FePt:SiO₂ films have been fabricated by annealing the as-deposited FePt/SiO₂ multilayers at temperatures from 450 to 650 °C. These films consist of high-anisotropy tetragonal L1₀ FePt particles embedded in a SiO₂ matrix. The structural and magnetic properties of these films were investigated. We have found that coercivity and grain size are highly dependent on the annealing temperature and SiO₂ concentration. Films with coercivities in the range from 2 to 8 kOe and grain sizes of 10 nm or less were obtained. These films have considerable potential as high-density magnetic recording media.

Laser Light In, 50-Mev Protons Out, Phillip F. Schewe, Ben Stein, Donald P. Umstadter

Donald Umstadter Publications

At next week's meeting of the American Physical Society Division of Plasma Physics in Seattle, three groups will independently announce their ability to generate powerful, intense streams of ions by shining ultrashort laser pulses on tiny spots of solid material. Potentially, this approach offers an alternative to bulky, expensive ion accelerators for producing high-velocity ions useful for cancer therapy and electronics manufacturing. Using a single pulse of light from Livermore's Petawatt laser, the most powerful in the world, researchers at that laboratory (Scott Wilks, 925-422-2974, wilks@icf.llnl.gov) have reported generating 30 trillion protons with energies up to 50 MeV, from a …

Confined Water In Hydrophobic Nanopores: Dynamics Of Freezing Into Bilayer Ice, Jan Slovak, Kenichiro Koga, Hideki Tanaka, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Molecular dynamics simulations for a thin film of water confined to a slit nanopore are performed in order to investigate the dynamic process of crystallization of the system. The system upon freezing creates a bilayer ice crystal composed of two layers of hexagonal rings. We perform one simulation at T=257 K during which the system remains a supercooled liquid state, and another one at T=253 K during which the system freezes. Many patterns of molecular arrangement are found upon freezing, and an account is given of the origin of multiple peaks in the distributions of binding energy and …

Imaging Point Defects In A Liquid Environment: A Model Afm Study, Kenichiro Koga, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Effects of the liquid on atomic force microscopy (AFM) imaging are examined for a model system consisting of a hexagonal flake of seven Lennard-Jones (LJ) atoms as a multiatom tip, a monolayer of LJ crystal containing a single point defect as a substrate, and three-site model water as the liquid. A previous simulation [Koutsos et al., Europhys. Lett. 26, 103 (1994)] has shown that the true atomic resolution of a point defect cannot be achieved in vacuum by use of the multiatom tip. Here we examine the feasibility of such atomic resolution when both the tip and substrate are immersed …

Center For Sustainable Agricultural Systems Newsletter, November/December 1999

Center for Sustainable Agricultural Systems -- Newsletters 1993-2000

Contents:

Conference Shows Large Interest in Small Farms

University Role in Biotechnology: What Do People Say and Why?

Loss of Biodiversity a Growing Concern

Measurement Of B Quark Fragmentation Fractions In The Production Of Strange And Light B Mesons In Pp̅ Collisions At √S =1.8 Tev, F. Abe, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

A new technique to measure the ratio of b quark fragmentation fractions in pp̅ collisions is described. Using a 70-pb^-1 sample of low-mass dimuon trigger data recorded with the Collider Detector at Fermilab, we identify B mesons by observing the double semileptonic decays b→cμX with c→sμ X. By counting the numbers of K*(892) ⁰, K*(892) ¹, and Φ (1020) mesons produced in association with these muon pairs, we measure the ratio of strange to nonstrange B meson production to be f_s /( f_u+ i>f_d)=[21.0±3.6(stat) _{-3.0 …}

The Probe, Issue 206 – November 1999

The Probe: Newsletter of the National Animal Damage Control Association

Wildlife Damage Conferences: When, Where, and Why? -- Robert M. Timm, Editor, THE PROBE
Booklet Review:"The Problem with Skunks!!" by Edward Kellems (34 pages, illustrated. $14.95)
New NWCO Web Page url is http://www.wildlifedamagecontrol.com/nwcoa.htm

Abstracts from the 2nd International Wildlife Management Congress, Hungary
Human Disturbance as a Design Factor to Aid Displacement of Canada Geese from Urban Parks -- P. C. Whitford, Biology Department, Capital University, Columbus, OH
Leopard Problems in Nepal -- T. M. Maskey, National Parks and Wildlife Conservation Department, Kathmandu, Nepal
Elk-human Conflict Management in Banff National Park, Alberta, Canada -- J. A. McKenzie, Banff National Park Wildlife …

Intensity Dependence Of Plateau Structures In Laser-Assisted X-Ray–Atom Scattering Processes, Dejan B. Miloševic, Anthony F. Starace

Anthony F. Starace Publications

The dependence on laser intensity of recently discovered plateau structures in laser-assisted x-ray–atom scattering, both with and without a static electric field present, is analyzed. Using the “three-step” model and the strong-field approximation we demonstrate a connection between laser-assisted, x-ray–atom scattering and high-order harmonic generation: For high laser-field intensities without a static field present, both processes have plateaus whose energies extend to the cutoff value 3.17U_p, where U_p is the ponderomotive potential energy. For x-ray–atom scattering in the presence of a static electric field we show that at high laser-field intensities two plateaus appear: One is …