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  • 1
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 1356-1358 
    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
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 1582-1584 
    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
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 635-637 
    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
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 40 (1999), S. 3175-3190 
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: The quantum supergroup OSPq(1|2n) is studied systematically. A Haar functional is constructed, and an algebraic version of the Peter–Weyl theory is extended to this quantum supergroup. Quantum homogeneous superspaces and quantum homogeneous supervector bundles are defined following the strategy of Connes' theory. Parabolic induction is developed by employing the quantum homogeneous supervector bundles. Quantum Frobenius reciprocity and a generalized Borel–Weil theorem are established for the induced representations. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 34 (1993), S. 988-996 
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: It is shown that in geometric quantization formulation, fractional statistics in a quantized system of N indistinguishable particles in two spatial dimensions arise from the nontrivial cohomology of the flat connection on the quantum line bundles as well as from the nontrivial homology of the configuration space. The propagator of a nonrelativistic interacting system with fractional statistics is derived.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 97 (1990), S. 0 
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary. The effect of dipalmitoylphosphatidylcholine (DPPC, L-αlecithin), a substance not containing arachidonic acid, on prostaglandin E (PGE) production of amniotic membrane was studied. DPPC (3.125800 μg/ml) stimulated PGE production of amniotic membrane (150200%), suggesting that lecithin, the major surfactant component, is directly involved in the mechanism of human parturition as a stimulator of PGE production.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 172-174 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A structure based on a bipolar transport/emitting layer is proposed and implemented for making organic light-emitting diodes. Compared to the conventional heterojunction organic light-emitting diodes, more than a factor of six improvement in device reliability (a projected operating lifetime of 70 000 h) is achieved in the structure. The significant improvement in device lifetime is attributed to the elimination of the heterointerface present in the conventional devices which greatly affects the device reliability. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 2538-2541 
    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
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Grass and forage science 58 (2003), S. 0 
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Sole crops and intercrops of wheat (Triticum aestivum L.) and bean (Vicia faba L.), at three harvest dates, representing successive growth stages, were evaluated for biomass production of whole-crop forage and quality characteristics of crude protein (CP), neutral-detergent fibre (NDF), acid-detergent fibre (ADF), water-soluble carbohydrate (WSC) concentrations and ash content. These tests were carried out for two field experiments, respectively, drilled during the spring of 1997 and autumn of 1997 on Imperial College Farm, Wye, UK. Results indicated that optimum forage yield and quality were obtained from the second to third harvest dates for the spring-drilled experiment and the second harvest for the autumn-drilled experiment. Wheat and bean intercrops were higher in total forage dry matter (DM) yield than either wheat or bean grown as sole crops. Field bean intercropped with wheat led to increased forage quality (CP and NDF concentrations) compared with sole wheat, and higher WSC concentrations compared with sole bean. Intercrops also enhanced weed suppression compared with sole bean. It is suggested that winter wheat–bean intercrops may have considerable potential as a moderate-yielding, relatively high-quality, low-input and environmentally benign forage crop with considerable potential with regard to yield and quality and warrant further study.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Cytokines production by T helper lymphocytes (Th cells), which orchestrate the interplay of the different cells involved in airway inflammation of asthma, may be reflected in peripheral blood. Some studies have suggested that the Th cell cytokines by peripheral blood T cells correlate with asthma severity.Objective To investigate the relationship between changes in IFN-γ production by peripheral blood T cells and changes in lung function in chronic stable asthmatics.Methods Sixteen patients with chronic stable moderate asthma aged 35–65 years (nine women) were recruited. Morning and evening peak expiratory flow rates (PEFR) monitoring and blood sampling for peripheral blood T cell culture, total IgE and blood eosinophils were performed at baseline and week 12. Levels of IFN-γ, IL-4 and IL-5 in culture supernatants of peripheral blood T cell were determined by using enzyme-linked immunosorbent assay (ELISA) kits.Results Patients with increased IFN-γ changes from baseline showed significantly increased changes in morning (P = 0.02) and evening (P 〈 0.05) PEFR compared with those with decreased IFN-γ changes. The changes in IFN-γ production and IFN-γ: IL-4 ratio significantly correlated with the changes in morning PEFR (Rs = 0.59, P 〈 0.02; Rs = 0.63, P 〈 0.01, respectively) and tended to correlate with the changes in evening PEFR (Rs = 0.45, P = 0.08; Rs = 0.5, P = 0.05, respectively). The changes in IL-4 and IL-5 did not correlate with the changes in IgE and blood eosinophils, respectively.Conclusions These findings suggest that IFN-γ may be associated with the alteration of lung function in asthmatics and play a role in the pathophysiology of chronic stable asthma.
    Type of Medium: Electronic Resource
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