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  • 1
    Electronic Resource
    Electronic Resource
    Effects of aperture displacement in broad-beam ion extraction systems : Papers from the Ninth International Conference on Ion Sources (2002)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 73 (2002), S. 928-930 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Low-energy broad-beam ion sources cover a wide range of applications. Geometrical perturbations of the axial-symmetric extraction channels by off-axis shifts of the accelerator grid holes give rise to an ion beamlet tilt which under certain conditions is dependent on the beamlet current. In this study, the characteristics of the beamlet deflection are presented which were obtained by a three-dimensional trajectory simulation. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1428785
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  • 2
    Electronic Resource
    Electronic Resource
    Broad-beam modeling and experiments for electric spacecraft propulsion : The 8th international conference on ion sources (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 732-734 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: At IOM Leipzig, we developed an efficient grid erosion simulation code. In our approach to ion beam extraction and grid erosion occurring in a multi-grid multi-aperture ion thruster we break down the complex interplay of pertinent elementary processes into consecutive steps. On the basis of ion optical and short-time grid-erosion measurements on a small broad-beam ion source, a comprehensive experimental validation of this code has been done. The good agreement between measured and simulated data furnishes confidence in the methodology. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1150277
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  • 3
    Electronic Resource
    Electronic Resource
    Approximation of the plasma inhomogeneity by broad-beam measurements and simulation : The 8th international conference on ion sources (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 678-680 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In broad-beam ion sources an inhomogeneous plasma distribution has a strong effect on both the maximum extractable ion current and the broad-beam profile. An approximate plasma distribution function is determined by fitting calculated accelerator-grid currents to corresponding experimental data, thus efficiently replacing complicated and expensive plasma probe measurements. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1150258
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  • 4
    Electronic Resource
    Electronic Resource
    Derivation of effective spin models from a three band model for CuO -planes (2002)
    Springer
    The European physical journal 28 (2002), S. 173-183 
    Details
    ISSN: 1434-6036
    Keywords: PACS. 71.10.Fd Lattice fermion models (Hubbard model, etc.) – 75.30.Et Exchange and superexchange interactions – 75.10.Jm Quantized spin models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The derivation of effective spin models describing the low energy magnetic properties of undoped CuO2-planes is reinvestigated. Our study aims at a quantitative determination of the parameters of effective spin models from those of a multi-band model and is supposed to be relevant to the analysis of recent improved experimental data on the spin wave spectrum of La2CuO4. Starting from a conventional three-band model we determine the exchange couplings for the nearest and next-nearest neighbor Heisenberg exchange as well as for 4- and 6-spin exchange terms via a direct perturbation expansion up to 12th (14th for the 4-spin term) order with respect to the copper-oxygen hopping tpd. Our results demonstrate that this perturbation expansion does not converge for hopping parameters of the relevant size. Well behaved extrapolations of the couplings are derived, however, in terms of Padé approximants. In order to check the significance of these results from the direct perturbation expansion we employ the Zhang-Rice reformulation of the three band model in terms of hybridizing oxygen Wannier orbitals centered at copper ion sites. In the Wannier notation the perturbation expansion is reorganized by an exact treatment of the strong site-diagonal hybridization. The perturbation expansion with respect to the weak intersite hybridizations is calculated up to 4th order for the Heisenberg coupling and up to 6th order for the 4-spin coupling. It shows excellent convergence and the results are in agreement with the Padé approximants of the direct expansion. The relevance of the 4-spin coupling as the leading correction to the nearest neighbor Heisenberg model is emphasized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjb/e2002-00219-5
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  • 5
    Electronic Resource
    Electronic Resource
    Familiäres Myoklonus-Dystonie-Syndrom assoziiert mit Panikattacken (2000)
    Springer
    Der Nervenarzt 71 (2000), S. 839-842 
    Details
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Myoklonus ; Dystonie ; Panikattacken ; Serotonin ; Keywords Myoclonus ; Dystonia ; Panic-disorder ; Serotonin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract We report a case of autosomal dominantly inherited dystonia and panic attacks to discuss successful treatment of a common serotonergic pathology with medication. The objective analysis of the movement disorder was done by Optotrak©. First we demonstrate a reduction of the myoclonus by L-5-hydroxytryptophan, which inhibits after 11 months. After changing the medication to Nefadozone, the myoclonus and the frequency of panic attacks were reduced.
    Notes: Zusammenfassung An einem Fallbeispiel mit autosomal-dominantem Stammbaum einer familiären Myoklonus-Dystonie und gleichzeitigem Auftreten von Panikattacken wird durch eine erfolgreiche medikamentöse Therapie eine der aktuellen Hypothesen bezüglich der Pathogenese und Therapie belegt. Die Dokumentation des Therapieerfolges wurde durch eine Tremor-Myoklonie-Analyse mit Hilfe des Optotrak©-Systems durchgeführt. Dabei zeigte sich in der primären Behandlung mit 5-Hydroxytryptophan zunächst eine Reduktion der Myoklonien. Nach 11 Monaten kam es zu einem Wirkungsverlust. Nach Umstellung der Medikation auf Nefadozon konnte neben einer positiven Beeinflussung der Myoklonien zusätzlich auch eine Frequenzreduktion der Panikattacken dokumentiert werden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001150050673
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