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  • 1
    Book
    Book
    Integer programming and combinatorial optimization; 6th international IPCO conference, Houston, Texas, June 1998, proceedings; 1412 (1998)
    Berlin u.a. :Springer,
    Details
    Title: Integer programming and combinatorial optimization; 6th international IPCO conference, Houston, Texas, June 1998, proceedings; 1412
    Contributer: Bixby, Robert E. , Boyd, E. Andrew , Rios-Mercado, Roger Z.
    Publisher: Berlin u.a. :Springer,
    Year of publication: 1998
    Pages: 435 S.
    Series Statement: Lecture notes in computer science 1412
    Type of Medium: Book
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    ZIB Catalog
    Zuse Institute Berlin get availability status
  • 2
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    Parallelizing the Dual Simplex Method (1996)
    Details
    Publication Date: 2014-11-11
    Description: We study the parallelization of the steepest-edge version of the dual simplex algorithm. Three different parallel implementations are examined, each of which is derived from the CPLEX dual simplex implementation. One alternative uses PVM, one general-purpose System V shared-memory constructs, and one the PowerC extension of C on a Silicon Graphics multi-processor. These versions were tested on different parallel platforms, including heterogeneous workstation clusters, Sun S20-502, Silicon Graphics multi-processors, and an IBM SP2. We report on our computational experience.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
    Format: application/postscript
    Format: application/pdf
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    OPUS
  • 3
    Electronic Resource
    Electronic Resource
    The development and advantages of beryllium capsules for the National Ignition Facility : The 39th annual meeting of division of plasma physics of APS (1998)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 5 (1998), S. 1953-1959 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Capsules with beryllium ablators have long been considered as alternatives to plastic for the National Ignition Facility laser [J. A. Paisner et al., Laser Focus World 30, 75 (1994)]; now the superior performance of beryllium is becoming well substantiated. Beryllium capsules have the advantages of high density, low opacity, high tensile strength, and high thermal conductivity. Three-dimensional (3-D) calculations with the HYDRA code [NTIS Document No. DE-96004569 (M. M. Marinak et al. in UCRL-LR-105821-95-3)] confirm two-dimensional (2-D) LASNEX [G. B. Zimmerman and W. L. Kruer, Comments Plasmas Phys. Controlled Thermonucl. Fusion 2, 51 (1975)] results that particular beryllium capsule designs are several times less sensitive than the CH point design to instability growth from deuterium-tritium (DT) ice roughness. These capsule designs contain more ablator mass and leave some beryllium unablated at ignition. By adjusting the level of copper dopant, the unablated mass can increase or decrease, with a corresponding decrease or increase in sensitivity to perturbations. A plastic capsule with the same ablator mass as the beryllium and leaving the same unablated mass also shows this reduced perturbation sensitivity. Beryllium's low opacity permits the creation of 250 eV capsule designs. Its high tensile strength allows it to contain DT fuel at room temperature. Its high thermal conductivity simplifies cryogenic fielding. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.872865
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  • 4
    Electronic Resource
    Electronic Resource
    Evanescent wave cavity ring-down spectroscopy with a total-internal-reflection minicavity (1997)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 2978-2989 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A miniature-cavity realization of the cavity ring-down concept, which permits extension of the technique to spectroscopy of surfaces, thin films, liquids, and, potentially, solids, is explored using a wave-optics model. The novel spectrometer design incorporates a monolithic, total-internal-reflection-ring cavity of regular polygonal geometry with at least one convex facet to induce stability. Evanescent waves generated by total-internal reflection probe absorption by matter in the vicinity of the cavity. Optical radiation enters or exits the resonator by photon tunneling, which permits precise control of input and output coupling. The broadband nature of total-internal reflection circumvents the narrow bandwidth restriction imposed by dielectric mirrors in conventional gas-phase cavity ring-down spectroscopy. Following a general discussion of design criteria, calculations are presented for square and octagonal cavity geometries that quantify intrinsic losses and reveal an optimal cavity size for each geometry. Calculated absorption spectra for the NO3 radical from 450 to 750 nm in a nitric acid solution are presented to demonstrate bandwidth and sensitivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1148230
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  • 5
    Electronic Resource
    Electronic Resource
    High repetition rate compact source of nanosecond pulses of 5–100 keV x-ray photons (1997)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 2292-2297 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A powerful, compact, and repetitive flash x-ray system based on a cable transformer technology powered by ceramic capacitors in a Blumlein-like configuration has been developed. Open circuit voltages in excess of 100 kV can be achieved while commutation occurs at low voltage (〈20 kV). The x-ray emission from a low impedance x-ray diode with a hollow cathode configuration was observed under a wide range of experimental conditions. The critical parameters limiting the flash x-ray performances are mainly the pressure in the x-ray diode and the anode–cathode space. This true table top device is able to produce doses up to 1 R per shot, measured at the output window, of x-rays between 5 and 100 keV. The pulse widths were about 20 ns and the maximum repetition rate was about 60 Hz. Operation is possible in air or in other gases (He, Ne, Ar, Kr, Xe, H2, N2) at pressures varying from 10−3 mbar for xenon to about 1 mbar for helium. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1148137
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  • 6
    Electronic Resource
    Electronic Resource
    Extraction studies on electron cyclotron resonance ion sources : Proceedings of the 6th international conference on ion sources (1996)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 1350-1352 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The production of radioactive ion beams in the SPIRAL project requires very efficient ion sources delivering beams with good optical properties. To improve these properties, the extraction conditions are under study. This paper will present the last results obtained with a new extraction system and will compare them to a numerical simulation. This comparison shows that the axial magnetic field influences the multicharged ion beam if the space charge during the acceleration is not compensated. In order to decrease the axial magnetic field effect on the extraction zone, a parallel beam can be formed with a multielectrode system. The first tests of this system will be presented. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1146662
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  • 7
    Electronic Resource
    Electronic Resource
    Rating Threat Mitigators: Faith in Experts, Governments, and Individuals Themselves to Create a Safer World (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Risk analysis 18 (1998), S. 0 
    Details
    ISSN: 1539-6924
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: This research explores public judgments about the threat-reducing potential of experts, individual behavior, and government spending. The data are responses of a national sample of 1225 to mail surveys that include measures of several dimensions of public judgments about violent crime, automobile accidents, hazardous chemical waste, air pollution, water pollution, global warming, AIDS, heart disease, and cancer. Beliefs about who can best mitigate threats are specific to classes of threats. In general, there is little faith that experts can do much about violent crime and automobile accidents, moderate faith in their ability to address problems of global warming, and greater expectations for expert solutions to the remaining threats. People judge individual behavior as effective in reducing the threats of violent crime, AIDS, heart disease, and automobile accidents but less so for the remaining threats. Faith in more government spending is highest for AIDS and the other two health items, lowest for the trio of violent crime, automobile accidents, and global warming, and moderate for the remaining threats. For most threats, people are not distributed at the extremes in judging mitigators. Strong attitudinal and demographic cleavages are also lacking, although some interesting relationships occur. This relative lack of sharp cleavages and the generally moderate opinion indicate ample opportunity for public education and risk communication.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1539-6924.1998.tb00368.x
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of Resin/Fluoride and Holmium: YAG Laser Irradiation on the Resistance to the Formation of Caries-Like Lesions (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of prosthodontics 6 (1997), S. 0 
    Details
    ISSN: 1532-849X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Purpose This study compared the effects of a combination of a topical application of resin/NaF mixture and holmium-doped yttrium aluminum garnet (HO:YAG) laser energy with untreated control sites for their resistance to acid destruction/mechanical challenges of root surfaces adjacent to restorative margins.Materials and Methods Forty-eight extracted human teeth were prepared for restorations with coronal margins in enamel and the apical margins on root surfaces. Four types of restorative materials were used. One half of the restorative/root surface margins were treated with an application of nonfilled resin/fluoride mixture and holmium-doped yttrium aluminum garnet laser irradiation; the remaining portion served as the untreated control for each tooth. Acid (10% formic) and mechanical (air sandblaster) challenges were used to test the effects of these treated sites to their controls and to other types of restorative/root surface margins. The depth of root surface loss within 0 to 2 mm apical from the restorative margins was measured and evaluated after 24, 48, and 72 hours of acid exposures.Results The measurements of tooth loss for the 24- and 48-hour acid-exposure cycles were subjected to statistical analysis (ANOVA) using a paired t test for the variables. The variables, depth of tooth surface loss for the control sites was compared with the depth of loss of the treated sites on opposing sides of each tooth. The depth of tooth surface loss for the control sites had an average mean of 0.35 (0.25) mm for the 24-hour acid exposures, with the opposing treated sides having a mean of 0.053 (0.05) mm (significant at the 0.05 level). The 48-hour acid-exposure results showed significant increased tooth loss for the control sites, but minimum additional loss on the treated sites. The control sites showed an average mean of 1.16 (0.24) mm and a mean of 0.095 (0.103) mm for the treated areas, significant at the 0.05 level. No measurements were made for the 72-hour cycle groups of composite and amalgam alloy restorations because of the loss of most of the filling materials in the control sites. The control groups of crowns showed an average mean loss of 2.06 (0.37) mm with only 0.20 (0.19) mm surface loss for the treated sites. The paired t test for variables indicated no significant differences of tooth surface loss between various types of restorative margins used in this study.Conclusions HO:YAG laser energy irradiation after application of resin/NaF to restorative margins and adjacent areas showed a significant increased resistance to acid/mechanical destruction on cementum-dentin root surfaces. The integrity of the restorative/dentin margins were maintained after extended exposures to formic acid and mechanical challenges.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1532-849X.1997.tb00060.x
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  • 9
    Electronic Resource
    Electronic Resource
    Inactivation of Brain Tryptophan Hydroxylase by Nitric Oxide (1996)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 67 (1996), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Tryptophan hydroxylase, the initial and rate-limiting enzyme in the biosynthesis of the neurotransmitter serotonin, is inactivated by nitric oxide (NO) and by the NO generators sodium nitroprusside, diethylamine/NO, S-nitroso-N-acetylpenicillamine, and S-nitrosocysteine. The inactivation occurs in an oxygen-free environment and is enhanced by dithiothreitol and ascorbic acid. Protection against the effect of NO on tryptophan hydroxylase is afforded by oxyhemoglobin, reduced glutathione, and exogenous Fe(II). Catalase partially protects the enzyme from NO-induced inactivation, whereas both superoxide dismutase and uric acid are without effect. These findings indicate that tryptophan hydroxylase is a target for NO and suggest that critical iron-sulfur groups in this enzyme serve as the substrate for NO-induced nitrosylation of the protein, resulting in enzyme inactivation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1996.67031072.x
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  • 10
    Electronic Resource
    Electronic Resource
    Tryptophan Hydroxylase: Cloning and Expression of the Rat Brain Enzyme in Mammalian Cells (1996)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 67 (1996), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: A cDNA encoding full-length tryptophan hydroxylase was produced by reverse transcriptase-PCR from rat brain mRNA and expressed transiently in a human fibroblast cell line. Catalytic activity was low unless transfected cells were grown in the presence of FeSO4. Recombinant tryptophan hydroxylase was found almost exclusively within the soluble compartment of the cell and was dependent on tryptophan and tetrahydrobiopterin for activity. The catalytic activity of recombinant tryptophan hydroxylase was stimulated 〉25-fold by Fe(II) and to a somewhat lesser extent by the polyanions heparin and phosphatidylserine. The enzyme was inhibited by desferrioxamine and dopamine, both of which complex iron. When extracts from transfected cells were subjected to sucrose gradient centrifugation and analytical gel filtration, the recombinant enzyme behaved the same as the native enzyme from brain. A monoclonal antibody against phenylalanine hydroxylase that cross-reacts with brain tryptophan hydroxylase was capable of immunoprecipitating the recombinant hydroxylase from solution. These data indicate that recombinant tryptophan hydroxylase expressed in mammalian cells is assembled into tetramers of ∼220,000 daltons. Its catalytic and physical properties appear to be very similar to those of the native enzyme from brain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1996.67030900.x
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