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  • 1990-1994  (185)
  • 1
    Electronic Resource
    Electronic Resource
    Simulation study on dynamics transition in neuronal activity during sleep cycle by using asynchronous and symmetry neural network model (1990)
    Springer
    Biological cybernetics 63 (1990), S. 243-250 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract We have found that single neuronal activities in different regions in the brain commonly exhibit the distinct dynamics transition during sleep-waking cycle in cats. Especially, power spectral densities of single neuronal activities change their profiles from the white to the 1/f along with sleep cycle from slow wave sleep (SWS) to paradoxical sleep (PS). Each region has different neural network structure and physiological function. This suggests a globally working mechanism may be underlying the dynamics transition we concern. Pharmacological studies have shown that a change in a wide-spread serotonergic input to these regions possibly causes the neuronal dynamics transition during sleep cycle. In this paper, based on these experimental results, an asynchronous and symmetry neural network model including inhibitory input, which represents the role of the serotonergic system, is utilized to examine the reality of our idea that the inhibitory input level varying during sleep cycle induce that transition. Simulation results show that the globally applied inhibitory input can control the dynamics of single neuronal state evolution in the artificial neural network: 1/f-like power spectral density profiles result under weak inhibition, which possibly corresponds to PS, and white profiles under strong inhibition, which possibly corresponds to SWS. An asynchronous neural network is known to change its state according to its energy function. The geometrical structure of network energy function is thought to vary along with the change in inhibitory level, which is expected to cause the dynamics transition of neuronal state evolution in the network model. These simulation results support the possibility that the serotonergic system is essential for the dynamics transition of single neuronal activities during sleep cycle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00203447
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  • 2
    Electronic Resource
    Electronic Resource
    Mapping the fermi surface of graphite with a display-type photoelectron spectrometer (1991)
    Springer
    Applied physics 52 (1991), S. 299-301 
    Details
    ISSN: 1432-0630
    Keywords: 79.60.Cn ; 71.25.Pi ; 71.25.Hc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A display spectrometer is used to image the momentum distribution of photoelectrons from the Fermi level in graphite. The Fermi “surface” consists of six points at the corners K of the hexagonal, two-dimensional Brillouin zone, in agreement with band theory. The method is also applied to other equal energy surfaces below the Fermi level, thereby giving the band dispersion of the π-bands.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00324768
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  • 3
    Electronic Resource
    Electronic Resource
    Molecular Biology of Cultured Cells from a Patient with Tuberous Sclerosis (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 615 (1991), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1991.tb37785.x
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of Al overlayer thickness on the leakage current of radiation detectors using Nb/Al-AlOx/Nb superconducting tunnel junctions (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 4761-4765 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Nb/Al-AlOx/Nb superconducting tunnel junctions for the application of radiation detectors were fabricated using dc magnetron sputtering. The surface morphology of polycrystalline Nb films was observed using an atomic force microscope. Junctions with various Al film thicknesses were fabricated. The leakage current of the junctions is found to decrease as the Al thickness increases, indicating an improvement of the Al film coverage over the Nb surface. X rays were detected with the junctions prepared and the low leakage property across the junction makes possible x-ray detection with various size junctions up to 200×200 μm2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357246
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  • 5
    Electronic Resource
    Electronic Resource
    Annealing dependence of coercivity, anisotropy field, and resistivity for amorphous CoZrNb films deposited by dc planar magnetron sputtering : 35th annual conference on magnetism and magnetic materials (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 5011-5013 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Amorphous CoZrNb films have been deposited by magnetron sputtering which can greatly improve the utilization efficiency of a magnetic alloy target with high permeability. The saturation magnetization 4πMs of the CoZrNb films was about 14 kG. The easy and hard axes of magnetization of the films were orthogonal to each other in the film plane. The coercivity Hc in the easy and hard directions decreased from 0.9 to 0.2 Oe after annealing in a rotating dc magnetic field HA. However, Hc increased drastically to 20 Oe by heating at the annealing temperature TA of 400 °C. With increasing TA and HA, the anisotropy field Hk gradually decreased from 12 to 1 Oe and the resistivity ρ also decreased from 200 to 150 μΩ cm. Consequently, it was found that Hc and ρ depended strongly on TA; and that Hk had definite relationships with both TA and HA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348158
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  • 6
    Electronic Resource
    Electronic Resource
    Dependence of saturation magnetization and coercivity of Co-Cr/Al multilayered films on Co-Cr layer thickness : The 5th Joint MMM−Intermag Conference (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6056-6058 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Co81Cr19/Al multilayered films with thicknesses of Co81Cr19 layers in the range of 46–170 A(ring) and Al ones of 7 A(ring) have been prepared on glass-slide substrate at room temperature by using the facing targets sputtering (FTS) apparatus. The dependence of the magnetic and crystallographic characteristics on the thickness of Co-Cr layers have been investigated. The magnetoresistance effect of the specimen films have been also examined. The intrinsic Co81Cr19 layers were composed of hcp phase crystallites with well orientation of the c axis normal to the film plane. Both the crystallinity of Co81Cr19 layers was improved and the d spacing between the c planes was expanded by using the Al interlayers as ultrathin as 7 A(ring). The easy direction of magnetization in the films was perpendicular to the film plane. The saturation magnetization, the coercivity, the in-plane squareness ratio and the anisotropy field depended strongly on the thickness of Co81Cr19 layer. On the other hand, the magnetoresistivity ratio was negative and its absolute value was as small as 0.13%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350044
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  • 7
    Electronic Resource
    Electronic Resource
    Refinement of time-resolved x-ray measurement system for studying the lattice deformation of silicon under pulsed Nd:YAG laser irradiation : Proceedings of the 4th international conference on synchrotron radiation instrumentation (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 1164-1167 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The time-resolved x-ray measurement system using the TAC technique and the MCS technique has been improved after the previous SRI conference. The improved TAC technique enables us to measure a time-resolved x-ray diffraction intensity distribution across a laser spot at any time after laser flashing with a time resolution of 25 ns under the multibunch operation of synchrotron radiation sources. Optical fiber delay units are developed for the MCS technique instead of ECL delay units to obtain long delay time for detective signals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143123
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  • 8
    Electronic Resource
    Electronic Resource
    Broadband reflectometry for the density profile and fluctuation measurements in the JT-60 tokamak (abstract) : Eight topical conference on high-temperature plasma diagnostics (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 3074-3074 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A broadband reflectometric system in O-mode operation has been developed for the density profile determination, MHD and turbulent fluctuation measurement, and evaluation of the particle diffusion coefficient in the JT-60 tokamak. For the profile determination, full Ka-Q band frequencies of BWOs have been swept in 750 μs, in order to minimize the effect of Doppler shift due to the fluctuation of reflection layers. The heterodyne fixed-frequency reflectometer has unveiled its effectiveness to probe MHD activities, diagnosing the m=1 tearing mode oscillations. It has also enabled the observation of the dramatic suppression of edge plasma density fluctuations at the L to H-mode transition in the LHCD limiter plasma. Furthermore, the propagation delay of density pulses has been observed by different fixed-frequency channels during a series of sawteeth, from which the particle diffusion coefficient was evaluated, with a newly proposed method applicable to fully diffusive plasmas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141738
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  • 9
    Electronic Resource
    Electronic Resource
    Broadband reflectometry for the density profile and fluctuation measurements in the JT-60 tokamak (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 3524-3527 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A broadband reflectometric system in O-mode operation has been developed for the density profile determination, MHD and turbulent fluctuation measurement, and evaluation of the particle diffusion coefficient in the JT-60 tokamak. For the profile determination, full Ka-Q band frequencies of BWOs have been swept in 750 μs, in order to minimize the effect of doppler shift due to the fluctuation of reflection layers. The heterodyne fixed-frequency reflectometer has unveiled its effectiveness to probe MHD activities, diagnosing the m=1 tearing mode oscillations. It has also enabled the observation of the dramatic suppression of edge plasma density fluctuations at the L- to H-mode transition in the LHCD limiter plasma. Furthermore, the propagation delay of density pulses has been observed by different fixed-frequency channels during a series of sawteeth, from which the particle diffusion coefficient was evaluated, with a newly proposed method applicable to fully diffusive plasmas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141562
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  • 10
    Electronic Resource
    Electronic Resource
    Differential gain of GaAs/AlGaAs quantum well and modulation-doped quantum well lasers (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 4-6 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The differential gain which is an important parameter for modulation dynamics in semiconductor lasers is evaluated experimentally by measuring the gain coefficient and the carrier lifetime in GaAs/AlGaAs double-heterostructure (DH) lasers, quantum well (QW) lasers, and p-modulation-doped quantum well (p-MDQW) lasers. The results indicate that the differential gain of the QW laser is 2.4 times as high as that of the DH laser, which is consistent with the theory. In addition, it is found that improvement of the differential gain using the p-MDQW structure is not so large as that expected by the theory. This result suggests that enhanced energy broadening due to the reduction of the equivalent dephasing time τeqin, which includes both the dephasing time τin due to the intraband relaxation and the band tailing effects, significantly affects the gain spectra in the p-MDQW lasers, which is confirmed by the measurement of the spontaneous emission spectra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104440
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