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  • 1995-1999  (5)
  • 1965-1969  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Study of the 4He(e,e′d)pn Reaction (1999)
    Springer
    Few body systems 26 (1999), S. 271-283 
    Details
    ISSN: 1432-5411
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract.  The cross section for the 4He(e,e′d)pn reaction has been measured in parallel and in (q, ω)-constant kinematics for values of the three-momentum transfer of 406, 495 and 595 MeV/c, and for a range in missing momentum. Just above threshold this reaction can be characterized as a spin/isospin flip transition of the involved pn pair. By using two electron energies (576 and 370 MeV) the longitudinal and transverse structure functions could be separated. The cross sections turn out to be purely transverse, as expected for a spin/isospin flip transition. The data are well described by new covariant and current-conserving calculations that include the major final-state interaction effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s006010050119
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    A Dutch Approach to Methicillin-Resistant Staphylococcus aureus (1999)
    Springer
    European journal of clinical microbiology & infectious diseases 18 (1999), S. 461-466 
    Details
    ISSN: 1435-4373
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100960050324
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Design of sparse matrix representations for the propagator used in the BPM and directional wave field decomposition (1997)
    Springer
    Optical and quantum electronics 29 (1997), S. 179-197 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Directional wave field decomposition can be accomplished with the aid of pseudo-differential operators. A fast numerical scheme requires sparse matrix representations of these operators. This paper focuses on designing sparse matrices for the propagator while keeping the accuracy high at the cost of ignoring critical-angle phenomena. The matrix representation follows from a rational approximation for the square root operator and the derivatives. The parameterization thus introduced lends itself to an overall optimization procedure that minimizes the errors for a chosen discretization rate. As such, the approach leads to an accurate propagator up to the (local) critical angle on a coarse numerical grid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018554105794
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    On the classification of discrete modes in lossy planar waveguides: the modal analysis revisited (1997)
    Springer
    Optical and quantum electronics 29 (1997), S. 243-262 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract In integrated-optical components such as integrated optical detectors or semiconductor light amplifiers, multilayer dielectric waveguiding structures occur in which some layers may be strongly lossy or may have gain. In such structures, the classification of the guided modes may become impossible. This paper reviews the modal analysis in which modes are only considered in connection with their possible excitation with a current line-source. Starting from the lossless situation, the analysis is extended to the lossy case and the details of the classification problem are investigated numerically. It was found that the validity of a unique classification is always limited. For that reason it is investigated, whether the classification problem might be due to the fact that in the time-harmonic formulation, the physical requirement of causality has been lost. To test this hypothesis, wave propagation is investigated along lossy waveguides in the timeLaplace-transform domain and using Lerch's causality theorem. It surprisingly turns out that in the time-Laplace-transform domain, the discrete part of the longitudinal spectrum does not exist, so that the test of the hypothesis is not conclusive. The classification problem of guided modes in strongly lossy waveguides is still an open problem.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018562307611
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Difference between TE and TM modal gain in amplifying waveguides: analysis and assessment of two perturbation approaches (1997)
    Springer
    Optical and quantum electronics 29 (1997), S. 263-273 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The commonly used confinement factor-based formula for modal gain in amplifying waveguides – gmod=Γgmat, with Γ a confinement factor – is well established and accurate for TE modes. The TM case is rarely, and sometimes erroneously, described in the literature. Using a variational formulation the fundamental difference between TE and TM modal gain is illustrated. An accurate expression, correct up to first order, for the TM modal gain is then derived from a known general perturbation formula. However, as this does not lead to a true confinement factor formulation, some approximations are introduced, leading to a unified formulation of both TE and TM modal gain. A second method to calculate the modal gain, based on the analyticity of the dispersion equation, is also discussed. Simulation and comparison with modal gain values from a complex mode solver will finally illustrate the validity of the different approaches.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018514424449
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Longitudinal propagation in a layered magneto-ionic medium (Epstein profile) (1967)
    Springer
    Flow, turbulence and combustion 17 (1967), S. 331-339 
    Details
    ISSN: 1573-1987
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary The longitudinal propagation and reflection of a plane electromagnetic wave in a horizontally stratified magneto-ionic medium is considered. In this case Maxwell's equations reduce to two uncoupled ordinary second-order differential equations, describing the propagation of two elliptically polarized plane waves. The electron density of the medium is assumed to vary with the vertical Cartesian coordinatez according to the Epstein law. Rigorous solutions of the relevant differential equations can be obtained either in the form of hypergeometric functions or in the form of an integral representation. The reflection coefficients of both waves are then expressed in terms of gamma functions. The following quantities are considered in detail in their dependence on the parameters involved: the modulus of the reflection coefficient, the phase delay time and the group delay time. Some numerical results are given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02116435
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    Paper (German National Licenses)
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