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1998

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Articles 2191 - 2220 of 2339

Full-Text Articles in Physical Sciences and Mathematics

Ophiomorpha Nodosa In Estuarine Sands Of The Lower Miocene Calvert Formation At The Pollack Farm Site, Delaware, Molly F. Miller, H. Allen Curran, Ronald L. Martino Jan 1998

Ophiomorpha Nodosa In Estuarine Sands Of The Lower Miocene Calvert Formation At The Pollack Farm Site, Delaware, Molly F. Miller, H. Allen Curran, Ronald L. Martino

Geosciences: Faculty Publications

No abstract provided.

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Measurement Of The He Ground State Lamb Shift Via The Two-Photon 1 1S-2 1S Transition, Scott D. Bergeson, A. Balakrishnan, K. G. H. Baldwin, T. B. Lucatorto, J. P. Marangos, T. J. Mcilrath, T. T. O'Brian, S. L. Rolston, C. J. Sansonetti, Jesse Wen, N. Westbrook, C. H. Cheng, E. E. Eyler Jan 1998

Measurement Of The He Ground State Lamb Shift Via The Two-Photon 1 1S-2 1S Transition, Scott D. Bergeson, A. Balakrishnan, K. G. H. Baldwin, T. B. Lucatorto, J. P. Marangos, T. J. Mcilrath, T. T. O'Brian, S. L. Rolston, C. J. Sansonetti, Jesse Wen, N. Westbrook, C. H. Cheng, E. E. Eyler

Faculty Publications

We have extended two-photon Doppler-free spectroscopy to the vacuum ultraviolet spectral region, to accurately measure the He 11S-21S transition at 120 nm. Our result is 4984872315(48) MHz. This yields a ground state Lamb shift of 41104(48) MHz, in fair agreement with theory and other experiments. This approach has the potential for significantly better accuracy once improvements in the laser and the wavelength metrology are implemented.

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Chief Factors And The Principal Block Of A Restricted Lie Algebra, Jorg Feldvoss Jan 1998

Chief Factors And The Principal Block Of A Restricted Lie Algebra, Jorg Feldvoss

University Faculty and Staff Publications

This paper is part of the conference proceedings from the conference titled The Monster and Lie Algebras that took place during a special research quarter at the Ohio State University in the spring of 1996. This conference was sponsored by the Ohio State University Mathematical Research Institute and the National Science Foundation. The focus of the conference was groups, Lie algebras, and the Monster, with emphasis on presenting the various aspects of group theory and Lie algebra theory from a modern perspective.

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Atomic Hydrogen Cleaning Of Inp(100) For Preparation Of A Negative Electron Affinity Photocathode, K. A. Elamrawi, M. A. Hafez, H. E. Elsayed-Ali Jan 1998

Atomic Hydrogen Cleaning Of Inp(100) For Preparation Of A Negative Electron Affinity Photocathode, K. A. Elamrawi, M. A. Hafez, H. E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

Atomic hydrogen cleaning is used to clean InP(100) negative electron affinity photocathodes. Reflection high-energy electron diffraction patterns of reconstructed, phosphorus-stabilized, InP(100) surfaces are obtained after cleaning at ∼400 °C. These surfaces produce high quantum efficiency photocathodes (∼8.5%), in response to 632.8 nm light. Without atomic hydrogen cleaning, activation of InP to negative electron affinity requires heating to ∼530 °C. At this high temperature, phosphorus evaporates preferentially and a rough surface is obtained. These surfaces produce low quantum efficiency photocathodes (∼0.1%). The use of reflection high-energy electron diffraction to measure the thickness of the deposited cesium layer during activation by correlating …

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Values Of The Federal Public Lands, Douglas S. Kenney, Gabriel D. Carter, Joshua M. Kerstein, University Of Colorado Boulder. Natural Resources Law Center, University Of Colorado Boulder. School Of Law, Turner Foundation, William & Flora Hewlett Foundation Jan 1998

Values Of The Federal Public Lands, Douglas S. Kenney, Gabriel D. Carter, Joshua M. Kerstein, University Of Colorado Boulder. Natural Resources Law Center, University Of Colorado Boulder. School Of Law, Turner Foundation, William & Flora Hewlett Foundation

Books, Reports, and Studies

v, 158 p. ; 28 cm

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The State Role In Western Watershed Initiatives, University Of Colorado Boulder. Natural Resources Law Center Jan 1998

The State Role In Western Watershed Initiatives, University Of Colorado Boulder. Natural Resources Law Center

Books, Reports, and Studies

vii, 91 p. ; 28 cm

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Metathesis-Based Synthesis Of Jasmonate And Homojasmonate Lactones, Candidates For Extracellular Quorum Sensing Molecules In Candida Albicans, Su C. Cho, Patrick Dussault, Amber D. Lisec, Ellen C. Jensen, Kenneth W. Nickerson Jan 1998

Metathesis-Based Synthesis Of Jasmonate And Homojasmonate Lactones, Candidates For Extracellular Quorum Sensing Molecules In Candida Albicans, Su C. Cho, Patrick Dussault, Amber D. Lisec, Ellen C. Jensen, Kenneth W. Nickerson

Department of Chemistry: Faculty Publications

Ring-closing metathesis of jasmonate esters is shown to provide a rapid entry to jasmonate lactones. The lactones were investigated as possible quorum sensing molecules for the fungi Candida albicans. Assays demonstrated no effect on fungal morphology at concentrations up to 96 mM.

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Subsurface Heavy-Metal Detection With The Use Of A Laser-Induced Breakdown Spectroscopy (Libs) Penetrometer System, Brian Miles, Javier Cortes Jan 1998

Subsurface Heavy-Metal Detection With The Use Of A Laser-Induced Breakdown Spectroscopy (Libs) Penetrometer System, Brian Miles, Javier Cortes

United States Army Corps of Engineers, Omaha District

U.S. Army Engineer Waterways Experiment Station (WES) investigators have designed, fabricated, and demonstrated a cone penetrometer sensor for subsurface in situ field screening based on LIBS. The LIBS probe (patent pending) presented here is one of a suite of contaminant and geophysical probes developed by the WES Site Characterization and Analysis Penetrometer System (SCAPS) program. The LIBS probe includes a laser as part of the optical LIBS sensor section for metals analysis and a cone and sleeve soil classification module at its tip. Soil classification data are acquired during the push, while LIBS data are recorded during probe retraction, after …

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Substituted Polythiophenes From Highly Reactive Zinc Reagents, Reuben D. Rieke Jan 1998

Substituted Polythiophenes From Highly Reactive Zinc Reagents, Reuben D. Rieke

Department of Chemistry: Faculty Publications

A novel Zerovalent zinc species and an organozinc reagent are disclosed. The zerovalent zinc species is directly pro duced by reaction of a reducing agent on a zinc salt, preferably Zn(CN)2. The organozinc reagent results from the reaction of the zerovalent zinc species and an organic compound having one or more stable anionic leaving groups. These organozinc reagents include a wide spectrum of functional groups in the organic radical, and are useful in a variety of reactions schemes.

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Cross-Coupling Of Organic Compounds Using Cuprous Odide, Reuben D. Rieke Jan 1998

Cross-Coupling Of Organic Compounds Using Cuprous Odide, Reuben D. Rieke

Department of Chemistry: Faculty Publications

Cross-coupling or addition reactions of organic compounds, including acid halides, allylic halides, and C.B-unsaturated carbonyl containing compounds, with organozinc com pounds may be readily and Safely carried out in the presence of cuprous iodide. The use of this catalyst in the coupling reaction provides for the preparation of commercially useful products in the pharmaceutical, agrochemical and other industries.

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Stable Isotopes And Sediments From Pickerel Lake, South Dakota, Usa: A 12ky Record Of Environmental Changes, Antje Schwalb, Walter E. Dean Jan 1998

Stable Isotopes And Sediments From Pickerel Lake, South Dakota, Usa: A 12ky Record Of Environmental Changes, Antje Schwalb, Walter E. Dean

United States Geological Survey: Staff Publications

Sedimentological parameters and stable O- and C-isotopic composition of marl and ostracode calcite selected from a 17.7 m long core from the 8 m deep center of Pickerel Lake, northeastern South Dakota, provide one of the longest (ca. 12ky) paleoenvironmental records from the northern Great Plains. The late Glacial to early Holocene climate in the northern Great Plains was characterized by changes from cold and wet to cold and dry, and back to cold and wet conditions. These climatic changes were controlled by fluctuations in the positions of the Laurentide ice sheet and the extent of glacial Lake Agassiz. We …

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Determination Of Bioavailable Contaminants In The Lower Missouri River Following The Flood Of 1993, Jimmie Petty, Barry Poulton, Colette Charbonneau, James Huckins, Susan Jones, Jennifer Cameron, Harry Prest Jan 1998

Determination Of Bioavailable Contaminants In The Lower Missouri River Following The Flood Of 1993, Jimmie Petty, Barry Poulton, Colette Charbonneau, James Huckins, Susan Jones, Jennifer Cameron, Harry Prest

United States Geological Survey: Staff Publications

The semipermeable membrane device (SPMD) technology was employed to determine the presence of bioavailable organochlorine pesticides (OCs), polychlorinated biphenyls (PCBs), and polyaromatic hydrocarbons (PAHs) in the water of the main stem of the lower Missouri River and three of its tributaries. The SPMDs were deployed in 1994 following the extensive flood of 1993. Specifically, the SPMDs were deployed for 28 days at Wilson State Park, IA; Nebraska City, NE; Parkville, MO; the Kansas River in Kansas City, KS; Napoleon, MO; the Grand River; Glasgow, MO; the Missouri River upstream from the confluence of the Gasconade River; the Gasconade River; and …

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Occurrence Of Pesticides In Shallow Groundwater Of The United States: Initial Results From The National Water-Quality Assessment Program, Dana Kolpin, Jake Barbash, Robert Gilliom Jan 1998

Occurrence Of Pesticides In Shallow Groundwater Of The United States: Initial Results From The National Water-Quality Assessment Program, Dana Kolpin, Jake Barbash, Robert Gilliom

United States Geological Survey: Staff Publications

The first phase of intensive data collection for the National Water-Quality Assessment (NAWQA) was completed during 1993-1995 in 20 major hydrologic basins of the United States. Groundwater land-use studies, designed to sample recently recharged groundwater (generally within 10 years) beneath specific land-use and hydrogeologic settings, are a major component of the groundwater quality assessment for NAWQA. Pesticide results from the 41 land use studies conducted during 1993-1995 indicate that pesticides were commonly detected in shallow groundwater, having been found at 54.4% of the 1034 sites sampled in agricultural and urban settings across the United States. Pesticide concentrations were generally low, …

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Seismic Rock-Physics Model For Carbonates At Low Effective Stress Levels Jan 1998

Seismic Rock-Physics Model For Carbonates At Low Effective Stress Levels

United States Geological Survey: Staff Publications

When considering the seismic response from the Dammam aquifer, the first required component is a simple model relating porosity and stress state to frame moduli assuming a carbonate matrix. We explored two such relationships, one based on the empirical regression presented by Domenico (1984) and a second using the critical porosity model of Nur et al. (1998) calibrated to the ultrasonic measurements of Nur and Simmons (1969). Once frame properties for a given porosity/pressure state were estimated, the effect of fluid changes were calculated using the low-frequency form of the Biot-Gassmann model, better known as Gassmann fluid substitution (Mavko …

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Stress And Structure Of Ni Monolayers On W(110): The Importance Of Lattice Mismatch, D. Sander, C. Schmidthals, Axel Enders, J. Kirschner Jan 1998

Stress And Structure Of Ni Monolayers On W(110): The Importance Of Lattice Mismatch, D. Sander, C. Schmidthals, Axel Enders, J. Kirschner

Axel Enders Publications

The combination of in situ stress measurements, low-energy electron diffraction, and scanning tunneling microscopy reveals the intimate relation between film structure and film stress for epitaxial growth of Ni on W(110) in the monolayer range. In contradiction to lattice mismatch considerations, we measure tremendous compressive stress in the pseudomorphic Ni film, where tensile film stress is expected from strain arguments. Surface stress of the film-substrate composite is proposed to be much more relevant for the description of film stress in the submonolayer range than lattice mismatch arguments are.

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Critical Point In Ferroelectric Langmuir-Blodgett Polymer Films, Stephen Ducharme, A.V. Bune, L.M. Blinov, V.M. Fridkin, S.P. Palto, A.V. Sorokin, S.G. Yudin Jan 1998

Critical Point In Ferroelectric Langmuir-Blodgett Polymer Films, Stephen Ducharme, A.V. Bune, L.M. Blinov, V.M. Fridkin, S.P. Palto, A.V. Sorokin, S.G. Yudin

Stephen Ducharme Publications

The ferroelectric critical point has been found in a ferroelectric polymer by exploring the influence of the electric field on the paraelectric-ferroelectric phase transition. Dielectric and pyroelectric measurements on 30-monolayer-thick films of the crystalline copolymer poly(vinylidene fluoride-trifluoroethylene) grown by Langmuir-Blodgett deposition show a single hysteresis loop below the zero-field phase transition temperature Tc0=80±10 °C, double hysteresis loops between Tc0 , and the critical temperature Tcr=145±5 °C, and no hysteresis above Tcr where the critical electric field is Ecr=0.93±0.1X109 V/m.

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Electron Attachment Energies Of The Dna Bases, Kayvan Aflatooni, Gordon A. Gallup, Paul Burrow Jan 1998

Electron Attachment Energies Of The Dna Bases, Kayvan Aflatooni, Gordon A. Gallup, Paul Burrow

Paul Burrow Publications

Injection of electrons into the empty π* molecular orbitals of uracil and the DNA bases creates short-lived anion states whose energies have been determined by electron scattering. A common range of attachment energies into the lowest orbitals is observed in all the bases. Evidence for nuclear motion during the lifetimes of the anions is found in all the compounds except adenine. These properties of the bases as bridge sites along the π-stack of DNA, namely, the effective degeneracy of the anion energies and the strong excitation of vibration, are key parameters for theories of electron-transfer rate, some of …

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Measurements Of The Meson-Photon Transition Form Factors Of Light Pseudoscalar Mesons At Large Momentum Transfer, J. Gronberg, Kenneth A. Bloom, Cleo Collaboration Jan 1998

Measurements Of The Meson-Photon Transition Form Factors Of Light Pseudoscalar Mesons At Large Momentum Transfer, J. Gronberg, Kenneth A. Bloom, Cleo Collaboration

Kenneth Bloom Publications

Using the CLEO II detector, we have measured the differential cross sections for exclusive two-photon production of light pseudoscalar mesons π0, η, and η′. From our measurements we have obtained the form factors associated with the electromagnetic transitions γ*γ → meson. We have measured these form factors in the momentum transfer ranges from 1.5 to 9, 20, and 30 GeV2 for π0, η, and η′, respectively, and have made comparisons to various theoretical predictions.

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Exponential Stability Of A Thermoelastic System With Free Boundary Conditions Without Mechanical Dissipation, George Avalos, Irena Lasiecka Jan 1998

Exponential Stability Of A Thermoelastic System With Free Boundary Conditions Without Mechanical Dissipation, George Avalos, Irena Lasiecka

Department of Mathematics: Faculty Publications

We show herein the uniform stability of a thermoelastic plate model with no added dissipative mechanism on the boundary (uniform stability of a thermoelastic plate with added boundary dissipation was shown in [J. Lagnese, Boundary Stabilization of Thin Plates, SIAM Stud. Appl. Math. 10, SIAM, Philadelphia, PA, 1989], as was that of the analytic case---where rotational forces are neglected---in [Z. Liu and S. Z. Heng, Quarterly Appl. Math., 55 (1997), pp. 551-564]). The proof is constructive in the sense that we make use of a multiplier with respect to the coupled system involved so as to generate a fortiori the …

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Evolution Of The Aeluroid Carnivora: Diversity Of The Earliest Aeluroids From Eurasia (Quercy, Hsanda-Gol) And The Origin Of Felids, Robert M. Hunt Jr. Jan 1998

Evolution Of The Aeluroid Carnivora: Diversity Of The Earliest Aeluroids From Eurasia (Quercy, Hsanda-Gol) And The Origin Of Felids, Robert M. Hunt Jr.

Department of Earth and Atmospheric Sciences: Faculty Publications

The oldest known fossil aeluroids are from Lower Oligocene sediments in France (Quercy) and Upper Eocene-Lower Oligocene sediments in Mongolia. These small (< 5 kg) carnivorans are primarily represented by mandibles, with hypercarnivorous dentitions in almost all lineages. The six aeluroid genera from France and those from Mongolia share a common dental pattern despite their geographic separation near the extremes of the Eurasian landmass. This similarity is not surprising, however, because faunal exchange across Eurasia at this time is documented not only by populations of small aeluroids but also by small arctoid carnivorans. Basicrania of Oligocene aeluroids are preserved only in the Quercy deposits. The auditory regions of two genera from Quercy (Palaeoprionodon, Stenoplesictis), and of two additional aeluroid genera (Stenogale, Proailurus) known only from mandibles at Quercy (but matched with congeneric mandibles with associated basicrania from early Miocene sediments at St.-Gerand), reveal a common basicranial morphotype. The living African palm civet Nandinia binotata retains a basicranial and auditory anatomy closely approaching the ancestral aeluroid morphotype. European paleontologists working with the Quercy faunas have regarded several of these aeluroids as early members of the Viverridae and …

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Amphicyonidae, Robert Hunt Jan 1998

Amphicyonidae, Robert Hunt

University of Nebraska State Museum: Mammalogy Papers

The Amphicyonidae occur in North America from late Eocene (~40 Ma) to early late Miocene (~9 Ma), a span of 31 million years. In the North American land mammal biochronology, this diverse family extends from the Duchesnean to the end of the Clarendonian and is especially well represented in the Miocene (~5-24 Ma). In the Old World, amphicyonids survive no longer than in North America: The last European records are Vallesian (Dinotheriensande, Mainz Basin, Germany, Kuss, 1965, Tobien, 1980; Vallés-Penédes Basin, Spain, Crusafont-Pairó and Kurten, 1976), and the last representative may occur at about 9 Ma at Kohfidisch, Austria (latest …

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Estimation Of Suspended Sediment Concentration In Water Using Integrated Surface Reflectance, Mahtab A. Lodhi, Donald C. Rundquist, Luoheng Han, Mark S. Kuzila Jan 1998

Estimation Of Suspended Sediment Concentration In Water Using Integrated Surface Reflectance, Mahtab A. Lodhi, Donald C. Rundquist, Luoheng Han, Mark S. Kuzila

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

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Resource News-Winter 1997-98 Jan 1998

Resource News-Winter 1997-98

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

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Resource News-Spring 1998 Jan 1998

Resource News-Spring 1998

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

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Mineral Facts For Nebraska, Excluding Oil And Gas, R. R. Burchett Jan 1998

Mineral Facts For Nebraska, Excluding Oil And Gas, R. R. Burchett

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

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Oil And Gas Facts For Nebraska, R. R. Burchett Jan 1998

Oil And Gas Facts For Nebraska, R. R. Burchett

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

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Twin Platte Natural Resources District Groundwater Quality Study, D. C. Gosselin, L. Howard, J. Goeke Jan 1998

Twin Platte Natural Resources District Groundwater Quality Study, D. C. Gosselin, L. Howard, J. Goeke

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

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Colfax County Test Hole Logs, Frank A. Smith, Raymond R. Burchett Jan 1998

Colfax County Test Hole Logs, Frank A. Smith, Raymond R. Burchett

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

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Dodge County Test Hole Logs, Frank A. Smith, Raymond R. Burchett Jan 1998

Dodge County Test Hole Logs, Frank A. Smith, Raymond R. Burchett

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

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Harlan County Test Hole Logs, Raymond R. Burchett Jan 1998

Harlan County Test Hole Logs, Raymond R. Burchett

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

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