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  • 1
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 2987-2989 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: For a bulk GaAs semiconductor laser amplifier the evolution of the optical gain after a 200 fs pulse excitation is calculated by including carrier–carrier and LO-phonon–carrier scattering in terms of the Boltzmann collision integrals. For an injected light pulse in the gain (absorption) region the optical gain shows a transient decrease (increase) followed by relaxation towards a lower (higher) level. Around the transparency point the broadening of the optical transition due to the decay of the induced interband polarization yields a transient decrease of the optical gain although the carrier density does not change. This behavior agrees qualitatively well with measurements of M. P. Kesler and E. P. Ippen [Appl. Phys. Lett. 51, 1765 (1987)]. The temperature relaxation after the excitation is examined. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Aufnahmesituation ; Qualitätssicherung ; Strukturqualität ; Prozeßqualität ; Aufnahmestation ; Key words Patients admission ; Quality assurance ; Admission ward ; Continuity of care
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The study provides empirical data to compare different systems used for hospital admission procedures in a psychiatric clinic. The Psychiatric University Clinic Basel replaced its traditional central admission ward by direct admission to a number of different treatment settings. This change had consequences for both structural and procedural quality. More admissions occurred after prior notice had been given, and these admissions occurred more often at a time of day when more clinic staff were available. The rate of voluntary admissions increased, and the continuity of care, as measured by the number of transfers within the clinic during the first 5 days post-admission, was improved. These findings, which support an interpretation that the treatment conditions were improved, must be balanced against the drawback of delayed decision-making processes with, for example, longer waiting times for the patient. However, the continuity of therapeutic relationships can be increased through further changes in the procedural quality.
    Notes: Zusammenfassung Die Untersuchung liefert empirische Daten zum Vergleich verschiedener Systeme zur stationären Aufnahme von Patienten in das psychiatrische Krankenhaus. In der psychiatrischen Universitätsklinik Basel wurde anstatt der bisherigen Aufnahme von Patienten über eine zentrale Aufnahmestation eine dezentrale Aufnahme auf verschiedenen Behandlungsstationen eingeführt. Diese Strukturveränderung hatte verschiedene Auswirkungen auf die Struktur- und Prozeßqualität. Es erfolgten mehr angemeldete Eintritte, und diese fanden häufiger zu Tageszeiten statt, in denen die Personalbesetzung günstiger ist. Die Rate freiwilliger Aufnahmen war erhöht und die Betreuungskontinuität, gemessen an der Anzahl der Verlegungen im Haus in den ersten 5 Tagen nach der Aufnahme, verbessert. Diesen Variablen, die für eine Verbesserung der Versorgungssitutation sprechen, stehen v. a. verlängerte Entscheidungsprozesse mit z. B. verlängerten Wartezeiten als Nachteile für die Patienten entgegen. Die Beziehungskontinuität kann durch weitere Veränderungen der Prozeßqualität noch erhöht werden.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 17 (1995), S. 1255-1264 
    ISSN: 0392-6737
    Keywords: Excitons and related phenomena (including electron-hole drops) ; Polaritons (including photon-photon and photon-magnon interactions) ; Conference proceedings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary We develop the bipolariton concept for a quasi-2D excitonic molecule (m) in quantum wells (QWLs). The bipolariton wave equation, which includes both the exciton-exciton (x-x) attraction and thex-photon (γ) coupling, is analysed. In the 2D bipolariton model, a quasi-2Dm exists in QWLs mainly as two quasi-boundsurface polaritons and, consequently, decays mainly into two outgoing surface polaritons. In quasi-2D GaAs QWLs the polariton renormalizations give rise to a «Mexican hat» structure in them dispersion at small momenta together with a considerable increase of both them effective binding energy ɛ m and the inversem radiative lifetimeГ m . A van Hove singularity in the joint density of polariton states is responsible for this effect.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 9 (1999), S. 309-314 
    ISSN: 1434-6036
    Keywords: PACS. 05.20.Dd Kinetic theory - 05.30.-d Quantum statistical mechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Numerical solutions of the Kadanoff-Baym equations with self-energies in second Born approximation are presented for electrons in a bulk semiconductor. The results are used to analyze in detail the two-time spectral function .In particular, (I) the damping of the spectral function is investigated over a broad density range both, for low and high temperatures; (II), is compared to analytical expressions - an exponential and a recently proposed inverse hyperbolic cosine decay law; (III), the two analytical spectral functions are studied with respect to conservation of total energy, where for the inverse hyperbolic cosine an improved behavior is demonstrated.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 1 (1998), S. 209-213 
    ISSN: 1434-6036
    Keywords: PACS. 78Optical properties, condensed-matter spectroscopy and other interactions of radiation and particles with condensed matter - 71.38.+iPolarons and electron-phonon interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: We compute numerically the time dependent retarded Green function of the polaron within the self-consistent RPA approximation. The results show an approximately Gaussian behaviour at t=0 changing at later times its concavity to an exponential decay, as it has been predicted in the approximate form of an inverse hyperbolic cosine function. The result contrasts with the non-selfconsistent RPA, where the exponential decay is only a transitory behaviour and the asymptotics is rather oscillatory. Our conclusions are significant in the context of the quantum kinetics with LO-phonons, where the transition from an intitially coherent scattering kinetics to a Markov kinetics with energy conservation is controlled by the time behaviour of the retarded Green function.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Flow-injection hydride generation and in situ concentration of As, Sb and Bi hydrides in graphite furnace atomic absorption spectrometry can be automated by means of a long-term stable trapping reagent replacing the Pd modifier. In a systematic study, carbide-forming elements (Zr, Nb, Ta, W) and noble metals (Ir, Ir/Mg, Pd/Ir) were investigated as stable adsorbers which require only a single application. Trapping temperature curves indicate high signals for trapping of As at 750–800 °C, Sb at 450–8000 °C and Bi at 100–500 °C on Zr-coated tubes. Ir- and Ir/Mg-coated tubes showed a high response for Sb and Bi at lower temperatures, but based on signal stability and reproducibility (over 400 trapping and atomization cycles tested) the better performance was found with the Zr-coated tubes. The radiotracers Sb-125 and Bi-207 were used to measure the hydride generation (〉95% for both elements) and trapping efficiency (91% for Sb and 56% for Bi) on the Zr-coated tube. An adsorptive “carry-over effect” was observed with Sb and Bi but not with As, and trapping temperatures above 450 °C with Sb and 350 °C with Bi (the “critical temperatures”) can lead to errors in absorbance values. On a Zr-coated tube the characteristic mass was about 16 pg for As, 15 pg for Sb and 9 pg for Bi (peak height) and the detection limits (3 sigma) were about 0.015, 0.010 and 0.027 ng, respectively, with a 1 ml sample loop. The method was tested by the determination of the elements in NIST low-alloy steel certified reference materials.
    Type of Medium: Electronic Resource
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