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  • 1
    Electronic Resource
    Electronic Resource
    Phonon-assisted recombination in GaAs/AlGaAs multiple-quantum-well structures (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 2538-2541 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The photoluminescence spectra of GaAs/AlGaAs multiple-quantum-well structures with varying thicknesses have been studied as a function of excitation intensity and polarization. An intense sideband luminescence with a narrow linewidth is observed at 36 meV below the band-to-band transition in all samples. These results, along with additional investigations detailed in this paper, support the conclusion that for the samples studied in these experiments this emission is a stimulated phonon-assisted recombination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344244
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Minority-carrier lifetimes in undoped AlGaAs/GaAs multiple quantum wells (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 635-637 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The lifetime of minority carriers in AlGaAs-GaAs quantum well structures grown by metalorganic chemical vapor deposition has been studied at room temperature and carrier densities up to 3×1016 cm−3 using time-resolved photoluminescence. Decay times are observed to be strongly dependent upon the quality of the AlGaAs barrier regions, excitation, and well width. Strong saturation of the decay times is observed with excitation indicating the presence of nonradiative traps. Saturated lifetimes as long as 650 ns have been measured in quantum wells with 200 A(ring) well widths.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100902
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  • 3
    Electronic Resource
    Electronic Resource
    Band-edge absorption coefficients from photoluminescence in semiconductor multiple quantum wells (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 1356-1358 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe a novel approach to determining absorption coefficients in thin films using luminescence. The technique avoids many of the difficulties typically encountered in measurements of thin samples, Fabry–Perot effects, for example, and can be applied to a variety of materials. We examine the absorption edge for GaAs/AlGaAs multiple quantum well structures with quantum well widths ranging from 54 to 193 A(ring). Urbach parameters and excitonic linewidths are tabulated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100714
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  • 4
    Electronic Resource
    Electronic Resource
    Electroabsorption in AlGaAs/GaAs multiple quantum well structures grown on a GaP transparent substrate (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 1582-1584 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The first measurements of electroabsorption in AlGaAs/GaAs multiple quantum wells grown on transparent GaP substrates are reported. High quality quantum well materials with sharp, well defined excitonic resonances are grown by employing a GaAsP intermediate layer between the quantum wells and the substrate. Good surface morphology and abrupt interfaces have been achieved with etch pit densities of 4×105 cm−2. A 7.5-meV shift of the absorption edge to lower energies is observed for field strengths of 8×104 V/cm. These structures are well suited for photonic switch array fabrication.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.98561
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  • 5
    Electronic Resource
    Electronic Resource
    Structure of a novel 3+2 enone cyclodimer (1986)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 42 (1986), S. 1842-1844 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108270186090339
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  • 6
    Electronic Resource
    Electronic Resource
    The general three-vertex, BRS identities and renormalizability of the light-cone gauge (1986)
    Springer
    The European physical journal 33 (1986), S. 107-114 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The general one-loop three-vertexГ μeλ abc (p, q, r) in the four-component formulation of the Yang-Mills theory is calculated in the light-cone gauge. The nonvanishing counter Lagrangian constructed from this three-vertex and the self-energy is proportional to the original Lagrangian, the single renormalization constant being -11g2 C YM Г(2−ω)/48π2. Gauge dependent and nonlocal counterterms do not contribute to the renormalization constant, but are needed to verify the appropriate Slavnov-Taylor (ST) and Becchi-Rouet-Stora (BRS) identities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01410457
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  • 7
    Electronic Resource
    Electronic Resource
    The light-cone gauge and the principal value prescription—Ward identities in Yang-Mills theories (1985)
    Springer
    The European physical journal 28 (1985), S. 579-586 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract By explicit calculation of radiative corrections to the self-energy and the three-vertex at one-loop level for Yang-Mills theories in the light-cone gauge, it is demonstrated that analytically regulated Feynman integrals defined by the principal value prescription satisfy the one, two, and three-point Ward identities. However, both the calculated self-energy and three-vertex have anomalous, unrenormalizable infinite parts, thus confirming the belief, based on previous calculations of only the self-energy, that the principal value prescription is seriously flawed in the light-cone gauge.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01474006
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  • 8
    Electronic Resource
    Electronic Resource
    Assessment of heat tolerance in potato (Solanum tuberosum ssp.tuberosum) under controlled environmental conditions: the ‘cutting technique’ (1988)
    Springer
    Potato research 31 (1988), S. 659-666 
    Details
    ISSN: 1871-4528
    Keywords: heat stress ; tuber yield ; clones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The ‘cutting technique’ or ‘tuberisation stimulus’ (TS) technique was investigated as a method of identifying heat tolerant clones ofSolanum tuberosum ssp.tuberosum. TS levels were assessed, using leaf cuttings, for 100 experimental clones growing under heat stress in a controlled environment (35/15°C day/night temperatures, 16 h photoperiod). No correlation was found with the tuber yields of these clones when grown in an irrigated trial in Israel. The relationship between TS levels and tuber production was investigated using early and later maturing cultivars grown with and without heat stress. These experiments showed that the cv. Blanka had high TS levels in all environments and high tuber fresh weights when grown under heat stress. However, the correlation between TS levels and tuber fresh weight for all cultivars was weak (r=0.45). The results indicated that this TS technique is unlikely to be an accurate method of screeningtuberosum clones for heat tolerance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02361859
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  • 9
    Electronic Resource
    Electronic Resource
    Automatic detection of sounds and murmurs in patients with lonescu-Shiley aortic bioprostheses (1989)
    Springer
    Medical & biological engineering & computing 27 (1989), S. 449-455 
    Details
    ISSN: 1741-0444
    Keywords: Bioprosthetic heart valves ; Heart sound detection ; Parameter extraction ; Phonocardiography ; Spectral analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The problems encountered in the automatic detection of cardiac sounds and murmurs are numerous. The phonocardiogram (PCG) is a complex signal produced by deterministic events such as the opening and closing of the heart valves, and by random phenomena such as blood-flow turbulence. In addition, background noise and the dependence of the PCG on the recording sites render automatic detection a difficult task. In the paper we present an iterative automatic detection algorithm based on the a priori knowledge of spectral and temporal characteristics of the first and second heart sounds, the valve opening clicks, and the systolic and diastolic murmurs. The algorithm uses estimates of the PCG envelope and noise level to identify iteratively the position and duration of the significant acoustic events contained in the PCG. The results indicate that it is particularly effective in detecting the second heart sound and the aortic component of the second heart sound in patients with lonescu-Shiley aortic valve bioprostheses. It has also some potential for the detection of the first heart sound, the systolic murmur and the diastolic murmur.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441460
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