Physical Sciences and Mathematics Commons^™

Nonlinear Effects Of Physisorption On Static Friction, G.T. Gao, Xiao Cheng Zeng, Dennis J. Diestler

Xiao Cheng Zeng Publications

The effects of a physisorbed film on the force of static friction in a model contact (monatomic adsorbate confined between plane-parallel walls) were investigated by Monte Carlo simulation. At fixed coverage the friction curve (shear yield stress vs normal stress) exhibits a marked nonlinearity, which results from a competition between adsorbate–wall interactions that predominate at low loads and wall–wall interactions that set in beyond a threshold load, which increases with coverage. Previous proximal-probe and computer experiments, carried out at high coverages, see only the initial (low-load) linear portion of the friction curve.

Effects Of Temperature Anomalies On The Palmer Drought Severity Index In The Central United States, Q. Steven Hu, Garry D. Wilson

School of Natural Resources: Faculty Publications

The purpose of this study is to improve our understanding of temperature and precipitation effects on the Palmer Drought Severity Index (PDSI). Both theoretical and observational analyses were applied to separate and compare temperature and precipitation effects on PDSI. The results showed that because of the dependence of PDSI on the ‘climatologically appropriate rainfall’, which is a function of time and varies with surface air temperature, the PDSI can be equally affected by temperature and precipitation, when both have similar magnitudes of anomalies. Calculations using observational data further illustrated the temperature influence on PDSI in different climate regions in the …

Cross Section For B-Jet Production In P̅P Collisions At √S = 1.8 Tev, B. Abbott, Gregory R. Snow, D0 Collaboration

Gregory Snow Publications

Bottom-quark production in p̅p collisions at √s = 1.8 TeV is studied with 5 pb^-1 of data collected in 1995 by the D0 detector at the Fermilab Tevatron Collider. The differential production cross section for b jets in the central rapidity region (∣y_b∣< 1) as a function of jet transverse energy is extracted from a muon-tagged jet sample. Within experimental and theoretical uncertainties, D0 results are found to be higher than, but compatible with, next-to-leading-order QCD predictions.

Measurement Of The W Boson Mass Using Large Rapidity Electrons, B. Abbott, Gregory R. Snow, D0 Collaboration

Gregory Snow Publications

We present a measurement of the W boson mass using data collected by the DØ. experiment at the Fermilab Tevatron during 1994–1995. We identify W bosons by their decays to en final states where the electron is detected in a forward calorimeter. We extract the W boson mass M_W by fitting the transverse mass and transverse electron and neutrino momentum spectra from a sample of 11 089 W→e_ν decay candidates. We use a sample of 1687 dielectron events, mostly due toZ→ee decays, to constrain our model of the detector response. Using the forward …

The Use Of Benthic Macroinvertebrates By Rainbow Trout (Oncorhynchus Mykiss) In Lake Ogallala, Nebraska, Tyler J. Pearson

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

No abstract provided.

Ecological And Physiological Factors Affecting Nesting Success Of Burrowing Owls In Buffalo Gap National Grassland, Randall L. Griebel

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

The western burrowing owl (Athene cunicularia hypugea) has been declining throughout much of its range, and in some areas, quite dramatically. In the Great Plains region, these declines appear to be closely associated with declines in prairie dog numbers. Most research to date has taken place on relatively small, fragmented prairie dog colonies. The objectives of this study were to analyze burrowing owl reproductive performance (i.e., clutch size, brood size, and number fledged), and nestling body condition in relation to nest level and colony level factors in Buffalo Gap National Grassland, South Dakota. Buffalo Gap contains large prairie …

The Prairie Naturalist Volume 32, No.4 December 2000

The Prairie Naturalist

LOCATING NESTS OF BIRDS IN GRASSLANDS FROM A MOBILE TOWER BLIND ▪ . T. F. Fondell, S. T. Hoekman, and L J. Ball

OBSERVATIONS ON SMALL MAMMALS RECOVERED FROM OWL PELLETS FROM NEBRASKA ▪ J J Huebschman, P. W Freeman, H. H. Genoways, and J A. Gubanyi

DlSTRIBUTION, HABITAT USE, AND NESTING SUCCESS OF HENSLOW'S SPARROW IN OKLAHOMA ▪ D. L. Reinking, D. A. Wiedenfeld, D. H. Wolfe, and R. W. Rohrbaugh, Jr.

REPRODUCTIVE SUCCESS OF PIPING PLOVERS ON ALKALI LAKES IN NORTH DAKOTA AND MONTANA ▪ R. K. Murphy, M. J. Rabenberg, M. L. Sondreal, B. R. Casler, and …

Water Current, Volume 32, No. 6, December 2000

Water Current Newsletter

Lake Classification Project Could Establish National Water Quality Ranking Procedure
From the Director: Profiling the Individuals and Efforts That Comprise the Water Center; Faculty Members Named to Administrative Posts
Meet the Faculty: David M. Admiraal; John C. Holz
Quality-Assessed Groundwater Pesticide Data Available Online
Groundwater Guardians
Pesticides Discovered in Ogallala Aquifer According to Recent USGS Study
Spring Semester Water Resources Seminar: Social Sciences Affect on Allocation of Water and Natural Resources
Nominations Solicited for 2001 Nebraska Water Conference
Water News Briefs
Congratulations to Our Winners
Avoid Fall Irrigation
TGF National Award Recipients
Our New Look
Watch Us on the Web …

Utility Of North Atlantic Right Whale Museum Specimens For Assessing Changes In Genetic Diversity, Howard C. Rosenbaum, Mary G. Egan, Phillip Clapham, Robert L. Brownell Jr., Sobia Malik, Moira Brown, Bradley White, Peter Walsh, Rob Desalle

United States Department of Commerce: Staff Publications

We examined six historical specimens of the endangered North Atlantic right whale (Eubalaena glacialis) using DNA isolated from documented baleen plates from the late nineteenth and early twentieth centuries. Sequences from the mitochondrial DNA (mtDNA) control region from these samples were compared with those from a near-exhaustive survey (269 of approximately 320 individuals) of the remaining right whales in the western North Atlantic Ocean. Our results suggest that there has been only relatively modest change in maternal lineage diversity over the past century in the North Atlantic right whale population. Any significant reduction in genetic variation in the …

Further Scrutiny Of Scientific Whaling, Robert L. Brownell Jr., Michael F. Tillman, Giuseppe Notarbartolo Di Sciara, Per Berggren, Andrew J. Read

United States Department of Commerce: Staff Publications

Normile reports on Japan's expanded scientific whaling program and notes that "Canada, the United States, the Soviet Union, South Africa, and Japan were among several countries that [conducted scientific whaling] before 1982 [the year the IWC passed the worldwide commercial moratorium on whaling], but in recent years Japan has stood alone." Although true, this statement omits three equally important points.

Ornithological Literature, Robert C. Beason

USDA Wildlife Services: Staff Publications

BABY BIRD PORTRAITS BY GEORGE MIKSCH SUTTON.

COLLINS ILLUSTRATED CHECKLIST: BIRDS OF SOUTHERN AFRICA.

BIRDS OF AFRICA: FROM SEABIRDS TO SEED-EATERS. By Chris and Tilde Stuart.

HARMONY AND CONFLICT IN THE LIVING WORLD. By Alexander F. Skutch.

HOPE IS THE THING WITH FEATHERS. By Christopher Cokinos.

STURKIE’S AVIAN PHYSIOLOGY. Edited by G. Causey Whittow.

STARLINGS AND MYNAS. By Chris Feare and Adrian Craig.

BIRDING IN THE AMERICAN WEST. By Kevin J. Zimmer.

TAKING WING: ARCHAEOPTERYX AND THE EVOLUTION OF BIRD FLIGHT. By Pat Shipman.

Stabilization Of Bound State Decay In An Intense Monochromatic High-Frequency Field, N. L. Manakov, M. V. Frolov, Bogdan Borca, Anthony F. Starace

Anthony F. Starace Publications

The formalism of complex quasienergies is used for exact calculation of the field-dependent decay rate for a weakly bound particle (in the model of a three-dimensional zero-range potential) in a strong monochromatic laser field. It is shown that the adiabatic (quasistationary) stabilization regime in this model occurs at frequencies ω exceeding the binding energy and only in a limited intensity range. A simple estimate is obtained for the critical field of stabilization breakdown. The effect may be observed for the decay of H^– ions in the field of a neodymium laser of femtosecond duration.

Surface Segregation And Restructuring Of Colossal-Magnetoresistant Manganese Perovskites La0.65Sr0.35Mno3, Hani Dulli, Peter A. Dowben, Sy-Hwang Liou, E. Ward Plummer

Department of Physics and Astronomy: Faculty Publications

We have investigated the surface chemical composition of crystalline films of La_0.65Sr_0.35MnO₃ by angle-resolved x-ray photoelectron spectroscopy. The surface composition was found to be significantly different from that of the bulk because of an appreciable Sr segregation. Furthermore, our study suggests that this Sr segregation has caused a major restructuring of the surface region characterized by the formation of a Ruddlesden-Popper phase (La,Sr)_n+1Mn_nO_3n+1 with n = 1. Segregation and restructuring in the surface region should be common in these doped perovskites and will have a profound impact on the electronic …

Measurement Of The Decay Amplitudes Of B0 → J/ΨK*0 And BS0 → J/Ψφ Decays, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

An angular analysis of B⁰ → J/ψK^*0and B_s⁰ → J/ψφ has been used to determine the decay amplitudes with parity-even longitudinal (A₀) and transverse (A_║) polarization and parity-odd transverse (A_┴) polarization. The measurements are based on 190 B⁰ and 40B_s⁰candidates obtained from 89 pb^-1 of p̅p collisions at the Fermilab Tevatron. The longitudinal decay amplitude dominates with |A₀|²= 0.59 ± 0.06 ± 0.01 for B⁰ and |A₀|^{2 …}

Magnetic Clusters On Single-Walled Carbon Nanotubes: The Kondo Effect In A One-Dimensional Host, Teri W. Odom, Jin-Lin Huang, Chin Li Cheung, Charles M. Lieber

Barry Chin Li Cheung Publications

Single-walled carbon nanotubes are ideal systems for investigating fundamental properties and applications of one-dimensional electronic systems. The interaction of magnetic impurities with electrons confined in one dimension has been studied by spatially resolving the local electronic density of states of small cobalt clusters on metallic single-walled nanotubes with a low-temperature scanning tunneling microscope. Spectroscopic measurements performed on and near these clusters exhibit a narrow peak near the Fermi level that has been identified as a Kondo resonance. Using the scanning tunneling microscope to fabricate ultra-small magnetic nanostructures consisting of small cobalt clusters on short nanotube pieces, spectroscopic studies of this …

Photonuclear Physics: Laser Splits Atom, Donald Umstadter

Donald Umstadter Publications

Lasers have become ubiquitous, being used in everything from a bar-code reader to a compact disk player. Who would have thought that they might be used to split the atom? A few scientists proposed to do just that more that a decade ago. But accomplishing it in the laboratory had to await the maturity of new technology, which enabled the construction of the world's most powerful lasers at the Lawrence Livermore National Laboratory in the United States and at the Rutherford Appleton Laboratory in the United Kingdom. Now two independent research teams have used these lasers to split the uranium …

Dijet Production By Double Pomeron Exchange At The Fermilab Tevatron, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We report the first observation of dijet events with a double Pomeron exchange topology produced in p̅p collisions at √s= 1800 GeV. The events are characterized by a leading antiproton, two jets in the central pseudorapidity region, and a large rapidity gap on the outgoing proton side. We present results on jet kinematics and production rates, compare them with corresponding results from single diffractive and inclusive dijet production, and test factorization.

Chemical And Biological Trends During Lake Evolution In Recently Deglaciated Terrain, Daniel R. Engstrom, Sherilyn C. Fritz, James E. Almendinger, Stephen Juggins

Department of Earth and Atmospheric Sciences: Faculty Publications

As newly formed landscapes evolve, physical and biological changes occur that are collectively known as primary succession. Although succession is a fundamental concept in ecology, it is poorly understood in the context of aquatic environments. The prevailing view is that lakes become more enriched in nutrients as they age, leading to increased biological production. Here we report the opposite pattern of lake development, observed from the water chemistry of lakes that formed at various times within the past 10,000 years during glacial retreat at Glacier Bay, Alaska. The lakes have grown more dilute and acidic with time, accumulated dissolved organic …

Control Of Intense Laser- Atom Processes With Strong Static Fields, Dejan B. Milosevic, Anthony F. Starace

Anthony F. Starace Publications

Atomic processes in the presence of intense fields continue to attract a great deal of attention [1-3]. Key goals of research in this area are to increase the intensities and frequencies of coherent light produced in these processes. In two recent works [4,5] we have demonstrated theoretically the possibility of controlling intense laser-atom interaction processes by employing strong, but experimentally feasible, static electric or magnetic fields. Thus, in Ref. [4] we demonstrated how a strong static electric field may induce a high-energy plateau for scattered x-ray photons in laser-assisted, x-ray-atom scattering in which the incident x-rays were assumed to have …

The Effectiveness Of The Asos, Mmts, Gill, And Crs Air Temperature Radiation Shields*, K. G. Hubbard, X. Lin, E.A. Walter-Shea

School of Natural Resources: Faculty Publications

Periodic upgrades of air temperature measurement systems in surface weather station networks cause data discontinuities. From a climatological viewpoint, it is necessary to evaluate the air temperature data discontinuities when air temperature radiation shields are upgraded. This study was undertaken to investigate the effectiveness of four common air temperature radiation shields including the Automated Surface Observing System (ASOS), the Maximum–Minimum Temperature System (MMTS), the Gill, and the Cotton Region Shelter (CRS) shields. The solar radiation shielding effectiveness for each shield under typical grass ground surface and different artificial surfaces (black, white, and aluminum) were investigated. The shield effectiveness was evaluated …

Angular Momentum Partitioning And Hexacontatetrapole Moments In Impulsively Excited Argon Ions, H. M. Al-Khateeb, B. G. Birdsey, Timothy J. Gay

Timothy J. Gay Publications

We have studied polarized electron collisions with Ar in which the target is simultaneously ionized and excited to form Ar⁺(3p⁴(¹D)4p) states. We measured the integrated Stokes parameters of the subsequent fluorescence emitted by the ²F_7/2, ²F_5/2, ²D_5/2, and ²P_3/2 states along the direction of electron polarization. The Rubin-Bederson hypothesis is shown to hold for the L and S multipoles of these states. The electric quadrupole and hexadecapole of the 1D core are derived. By recoupling these moments with …

Comparative Studies Of Dissociative Electron Attachment To Methyl Halides, R. S. Wilde, Gordon A. Gallup, Ilya I. Fabrikant

Gordon Gallup Publications

The dissociative electron attachment cross sections for the methyl halides vary in an enormous range from the virtually unmeasurable 10⁻²³ cm² for CH₃Cl at room temperature to 10⁻¹⁴ cm² for CH₃I. In this paper we supplement our previous studies by calculations of dissociative electron attachment to CH₃Br and compare results for all methyl halides studied so far. The rate as a function of temperature for CH₃Cl and CH₃Br exhibits an exponential dependence on 1/T (Arrhenius law) with the activation energy lower for CH₃Br. …

Report Of The Qcd Tools Working Group, R. K. Ellis, R. Field, S. Mrenna, Gregory R. Snow, C. Balazs, E. Boos, J. Campbell, R. Demina, J. Huston, C-Y. P. Ngan, A. Petrelli, I. Puljak, T. Sjostrand, J. Smith, D. Stuart, K. Sumorok

Gregory Snow Publications

We report on the activities of the “QCD Tools for heavy flavors and new physics searches” working group of the Run II Workshop on QCD and Weak Bosons. The contributions cover the topics of improved parton showering and comparisons of Monte Carlo programs and resummation calculations, recent developments in Pythia, the methodology of measuring backgrounds to new physics searches, variable flavor number schemes for heavy quark electro-production, the underlying event in hard scattering processes, and the Monte Carlo MCFM for NLO processes.

Tabletop Accelerators Are Brighter And Faster, Phil Schewe, Ben Stein, Donald P. Umstadter

Donald Umstadter Publications

At last week's APS plasma physics meeting, Donald Umstadter of the University of Michigan's Center for Ultrafast Optical Science (734-764-2284, dpu@umich.edu) reported on advances at his lab and elsewhere in tabletop laser accelerators, devices that use light to accelerate beams of electrons and protons to energies of a million volts in distances of only microns. This acceleration rate or "gradient" is up to a thousand times larger than in conventional accelerators because the tabletop laser light can now exert pressures of gigabars, the highest ever achieved, and approaching the pressure of light near the Sun. Not only that, but Umstadter's …

Horse Creek Fen, Birdwood Creek And Kelly Ranch Inventory, Robert F. Steinauer

Nebraska Game and Parks Commission: White Papers, Conference Presentations, and Manuscripts

Horse Creek Fen preserve is a complex of wetland communities (Sandhills fen, Sandhills freshwater marsh, and northern sedge wet meadow) associated with Horse Creek, a ditched stream that drains the Allen Valley fen. Fen vegetation on the preserve is limited to approximately 20 acres on the western boundary of the preserve where it abuts the eastern end of the Allen Valley fen (Steinauer et al. 1996). The fen vegetation is surrounded primarily by Sandhills freshwater marsh, which in turn is surrounded by northern sedge wet meadow. Additional Sandhills freshwater marsh occurs near the eastern boundary of the preserve. The eastern …

Control Of High-Harmonic Generation And Laser-Assisted X-Ray-Atom Scattering With Static Electric And Magnetic Fields, D. B. Milošević, Anthony F. Starace

Anthony F. Starace Publications

We consider the use of strong static fields to control two related atomic processes: laser-assisted x-ray-atom scattering (XAS) and high-harmonic generation (HHG). We first analyze the laser field intensity dependence of the differential cross section (DCS) plateau structures for the laser-assisted XAS process in the presence of a static electric field as a function of the number of photons exchanged with the laser field. Besides the recently discovered (Milošević, D.B. and Starace, A.F., 1998, Phys. Rev. Lett., 81, 5097) extended plateau for absorbed photons, which indicates a substantial increase of the scattered x-ray energies, a new plateau, having many …

Direct Measurement Of The W Boson Width In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

This Letter describes a direct measurement of the W boson total decay width, Γ _W, using the Collider Detector at Fermilab. The measurement uses an integrated luminosity of 90 pb^-1, collected during the 1994–1995 run of the Fermilab Tevatron pp̅ collider. The width is determined by normalizing predicted signal and background distributions to 49 844 W→ eν candidates and 21 806 W→μν candidates in the transverse-mass region M_T < 200 GeV and then fitting the predicted shape to the 438 electron events and 196 muon events in the high-M_T region, 100<M_T < 200 GeV. The result is G Γ _W= 2.04 ± 0.11(stat) ± 0.09(syst) GeV.

Measurement Of J/Ψ And Ψ(2s) Polarization In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We have measured the polarization of J/ψ and ψ(2S) mesons produced in pp̅ collisions at √s= 1.8 TeV, using data collected at the Collider Detector at Fermilab during 1992–1995. The polarization of promptly produced J/ψ[ψ(2S)] mesons is isolated from those produced in B-hadron decay, and measured over the kinematic range 4 [5.5] < P_T < 20 GeV/c and |y| < 0.6. For P_T≥ 12 GeV/c we do not observe significant polarization in the prompt component.

Nonadiabatic Heat-Capacity Measurements Using A Superconducting Quantum Interference Device Magnetometer, A.I. Kharkovski, Christian Binek, Wolfgang Kleeman

Christian Binek Publications

Nonadiabatic measurements of the heat capacity involving sample-inherent thermometry are proposed. The method is realized with superconducting quantum interference device magnetometry and applied to FeBr₂ single crystals by using the magnetization for both thermometry and relaxation calorimetry. When heating with a step pulse of laser light, the magnetization relaxes on a characteristic time scale Ί = RC, where C is the heat capacity and R is the heat resistance between the sample and the bath. R is independently determined from the temperature dependence of the magnetic moment measured with and without stationary light irradiation. ©2000 American Institute of …

Closing - Conference Summary, James E. Miller

Wildlife Damage Management Conference Proceedings

It has been a distinct pleasure for me to have attended and participated in each of the previous eight Eastern Wildlife Damage Management Conferences, dating back to 1983, as a member of the planning committees, as well as for this first Wildlife Damage Management Conference. I have enjoyed participating, learning from each conference, as well as visiting with old friends and colleagues and meeting new colleagues. Although I have been around long enough to know that no matter how hard you try you can't please everyone, I ask those of you who enjoyed participating in this Conference to join me …