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  • 1
    Electronic Resource
    Electronic Resource
    Competition between two resonance frequency branches in a waveguide free-electron laser (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 426-428 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: One of the problems encountered in designing a waveguide free-electron laser (FEL) is to suppress the lower-frequency branch, which may have a higher gain than the more useful higher-frequency branch. It is shown that the electron pulse length and energy spread strongly influence the competition between the gains at high and low frequency for a waveguide FEL. It is also found that the negative slippage that may take place at the lower-frequency branch results in larger reduction in gain than the positive slippage. The maximum allowable electron energy spread for both resonance frequencies is derived. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359347
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  • 2
    Electronic Resource
    Electronic Resource
    Compact electron-accelerator system using laser-induced photoelectrons and DISKTRON electrostatic accelerator (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 1010-1014 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new type of relativistic electron acceleration facility is being developed by the Laser Science Research Group at The Institute of Physical and Chemical Research. It utilizes laser-induced photoelectrons accelerated by a compact DISKTRON electrostatic accelerator, which makes it possible to generate a controllable bright short-pulsed electron beam up to the energy of 1 MeV with a low emittance (〈2×10−5 mrad) and high current density (∼500 A/cm2) without any guiding field. The characteristics of the entire facility and some of the key components are described in detail. The experimental results which confirm the possibilities of increasing quantum efficiency of metal photocathodes by geometric alteration are reported. Observation of laser undulator effects in the visible wavelength was demonstrated in the facility. The coming use of the system includes a far-infrared/submillimeter free-electron laser using a microwiggler and generation of extreme ultraviolet radiation by the laser undulator. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1146037
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  • 3
    Electronic Resource
    Electronic Resource
    Development and quality measurements of cold relativistic electron beam for low-γ free-electron lasers (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 2789-2793 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A relativistic electron beam source with low temperature (cold) using a field emission cathode and uniform electrostatic acceleration has been developed for use in low-γ free-electron lasers. An energy of 0.51 MeV and a current of 60 A (200 A/cm2) were obtained. The energy spread and the angular velocity spread were measured to be ΔE/E=0.14% and β⊥/β(parallel) =4×10−2, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344205
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of deep levels on the optoelectronic properties of InGaAs/InAlAs multiquantum-well structures (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 1955-1960 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Deep electron-trapping centers present in InAlAs (barrier layers) are found to have significant effects on the optoelectronic properties of InGaAs/InAlAs multiquantum-well structures grown by molecular-beam epitaxy. When the energy depths of these centers are less than the discontinuity of the conduction band for this heterojunction, they come to be ionized to produce two-dimensional electron gas in the quantum well (InGaAs). The excess electrons thus accumulated dissociate the excitons by screening the attractive potential between electrons and holes. Hence, the deep levels in barrier layers must be reduced in order to improve the optoelectronic quality of this class of multiquantum-well structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341093
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  • 5
    Electronic Resource
    Electronic Resource
    Electric field effects in excitonic absorption for high-quality InGaAs/InAlAs multiple-quantum-well structures (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 2795-2797 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electric field effects in excitonic absorption characteristics are studied for high-quality InGaAs/InAlAs multiple-quantum-well structures grown by molecular beam epitaxy. The minute comparison between the experimental and theoretical results verifies the following: first, the variations of exciton levels in the first subband show excellent agreement with the calculations; second, the exciton level in the second subband shows a shift to the higher energy (blue shift).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341582
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  • 6
    Electronic Resource
    Electronic Resource
    InGaAs/InAlAs bistable multiple quantum well lasers with large on/off ratio using the resonant tunneling effect (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 1462-1464 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Bistable operation with a large on/off ratio of 800:1 is achieved in InGaAs/InAlAs multiple quantum well (MQW) lasers using the resonant tunneling effect at 77 K. Structural dependence of resonant tunneling characteristic in the MQW structures reveals that the threshold current density, at which negative differential resistance appears, increases drastically when the InAlAs barrier width of MQW structures decreases. The increase in the threshold current density has led to an improvement in the bistable characteristics of InGaAs/InAlAs MQW lasers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.99967
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  • 7
    Electronic Resource
    Electronic Resource
    Direct evidence of the indirect energy gap in InAlAs/AlAsSb multiple quantum wells by time-resolved photoluminescence (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 1620-1622 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Time-resolved photoluminescence spectroscopy has been applied to determine the nature of the energy gap of InAlAs/AlAsSb multiple quantum well structures. While the InAlAs buffer layer exhibits a decay time of the order of 1 ns, which is typical for direct gap semiconductors, the decay time of the InAlAs/AlAsSb multiple quantum well structures is prolonged by more than two orders of magnitude. This observation is direct evidence for the presence of an indirect energy gap. The decay time increases with increasing InAlAs layer thickness indicating the decreasing overlap of electron and hole wave functions. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121132
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  • 8
    Electronic Resource
    Electronic Resource
    Ultrafast 1.55 μm all-optical switching using low-temperature-grown multiple quantum wells (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 153-155 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Low-temperature grown surface-reflection all-optical switching has been demonstrated with ultrafast photoresponse (1.5 ps), low switching energy (2 pJ), high-contrast (13 dB), polarization independence, and wide operation wavelength range in the 1.55 μm band using low-temperature-grown Be-doped strained InGaAs/InAlAs multiple quantum wells. The combination of low-temperature growth and Be-doping contributes to the ultrafast photoresponse. Additionally, the introduction of compressive strain and a mirror with 1% reflectivity greatly enhances optical nonlinearities. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.116131
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of texture of food on chewing patterns in the human subject (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of oral rehabilitation 16 (1989), S. 0 
    Details
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: To elucidate the effects of food character on chewing patterns in humans, the electromyographic activity (EMG) of the chewing muscles and also the jaw movements were recorded in twenty-nine young subjects during ordinary chewing of five different foods.The results obtained were as follows. (a) The harder food materials showed a higher amplitude of the masseter EMG than the softer ones. (b) Concerning the number of chewing strokes and the elapse of time until the last swallowing action, subjects could be divided into two groups. (i) In the first major group, the number of chewing strokes and chewing time until the last swallowing action increased following increase of hardness of the food. This suggests that chewing force and chewing movements may be strongly influenced by the texture of food, especially its hardness. Further, the degree of pulverization of eating materials appears to be the major factor in controlling the swallowing action. (ii) In the second minor group, the chewing strokes and the chewing time were less influenced by the hardness of food. Here, a certain number of chewing strokes could be stimulating the swallowing centre in the brain and so induce swallowing, regardless of the degree of pulverization of the food.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2842.1989.tb01331.x
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  • 10
    Electronic Resource
    Electronic Resource
    Cutaneous focal mucinosis (1989)
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 121 (1989), S. 0 
    Details
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A 39-year-old man had typical cutaneous focal mucinosis on the left forearm. The fibroblasts in the myxomatous lesion had many cytoplasmic vesicles, and on electron microscopy, these were compatible with condensing vacuoles or secretory granules. The fibroblasts in this case were considered to be mucoblasts involved in the over-production of the ground substance, that was mainly composed of hyaluronic acid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2133.1989.tb15521.x
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