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  • 2000-2004  (1)
  • 1990-1994  (4)
  • 1965-1969  (2)
  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 4709-4714 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Stochastic dynamics simulations of n-alkane melts (C13H28 and C28H58 ) have been performed in order to calculate their static properties. The system consists of linear chains of mass points, which are connected by fixed bond lengths. Each point of a chain is subjected to valence bond and torsional forces. Additionally, nonbonded interactions are taken into account by a truncated, Lennard-Jones potential. The mean-square end-to-end distance and the radius of gyration of the chains as well as the average fraction of trans conformations were calculated and compared with the results obtained by Monte Carlo simulations and by unperturbed rotational isomeric states model calculations. The comparison exhibits very good agreement between the results of the different approaches, and demonstrates the potential advantages of stochastic dynamics simulations for polymeric systems. An investigation of different torsional potentials exhibited the subtle effect of the curvature of the torsional potential on bulk structures.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 195 (1966), S. 20-25 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We propose a study of the second-order coherence properties of radiation, such as inelastically scattered laser light, by performing an excess photon coincidence rate experiment a la Hanbury Brown-Twiss. The calculation evaluates the second-order correlation function of the electromagnetic field for an arbitrary number of coherent modes overlapped in phase space by a chaotic radiation field. We discuss the application of the general result to a specific case, namely the case of a single mode laser, and the Stokes radiation produced in a Brillouin-active medium, and a suitable part of the spectrum produced by causing dielectric breakdown in air.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 204 (1967), S. 345-350 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Various non-leptonic decay modes of baryons are calculated in a simple quark model. Form factors for various matrix elements are taken both from experiment and the quark model. Additionally theK→2π andK→3π decay modes are computed in the same model. The theory has theΔ I=1/2 rule and static SU6 built-in. A relation between the∑ +→N + π + decay, not calculable in the model, and theK→3π decay is given via an effective six quark interaction. Agreement with experiment is order of magnitude for the baryonic decays and worse for theK decays.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of superconductivity 13 (2000), S. 907-909 
    ISSN: 1572-9605
    Keywords: Coulomb interaction ; low-energy electronic collective modes ; phonon–plasmon scenarios
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The Coulomb interaction induces low-energy electronic collective modes (LEECM) in layered conductors. We study how the superconducting critical temperature T c is affected by such collective modes within the strong-coupling theory of superconductivity. Whereas we account for both the electron–phonon and the screened Coulomb interactions, the main focus is set on the latter. The dielectric function is displayed and screening within RPA is discussed. We then show that LEECM affect the superconducting state constructively in layered structures. Their effect can be interpreted as a negative μ* in the Eliashberg theory. We examine in what respect the collective-mode scenario differs in layered conductors as compared to three-dimensional (3D) isotropic metals.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 90 (1993), S. 277-281 
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The plasmon density of states (DOS)p(ω) of a layered electron gas (LEG) is studied theoretically. It is shown thatp(ω) is a linear function of frequency ω as ω goes to 0, and then increases more rapidly as ω tends to the screened, three dimensional plasma frequency ωp. We also study the partial densities of state for constantK andq z , whereK andq z are the magnitude of the transverse and perpendicular momentum transfers. A possible experimental probe for the plasmon DOS is discussed.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of superconductivity 3 (1990), S. 227-231 
    ISSN: 1572-9605
    Keywords: Positron annihilation ; theory ; high-temperature superconductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The superconducting transition affects the positron-annihilation lifetime in the high-Tc oxides. This effect is due to the unusual properties of the oxides in the normal state and, in particular, to the small Fermi energy. The value of the shift also depends on the interlayer distance.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical methods of operations research 34 (1990), S. 143-156 
    ISSN: 1432-5217
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Summary In business surveys, the response categories most often are of the type “increase”, “no increase” and “decrease”. In modelling how the response variable depends on exogeneous variables one has to decide whether the response categories can be treated as ordered or unordered categories. Though the response categories are constructed as ordered categories it is not so clear that the respondent actually uses them as ordered. The middle category may be used as a “don't know” category if the respondent has insufficient information. Here categorical regression models are considered for the ordered and the unordered case. Three types of models are investigated: unordered models resulting from utility maximization, threshold models and two-step models which treat the middle category explicitely as a separate category. The relationship between models is considered. The models are applied to a sample of the IFO-Konjunkturtest and are compared to each other.
    Type of Medium: Electronic Resource
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