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  • 1
    Electronic Resource
    Electronic Resource
    Theoretical calculation of impact ionization rate in SiO2 (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1100-1105 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Impact ionization rate in SiO2 was numerically calculated using both pseudo-wave functions and energy band structure based on a self-consistent pseudopotential method. To avoid numerical complexity due to amorphous structure, SiO2 was assumed to be a crystalline α-quartz. The calculated impact ionization rate shows a strong wave vector anisotropy near a threshold energy regime, primary electrons existing at Γ point yield the strongest impact ionization rate. It was found that calculated results are not expressed by a Keldysh formula since SiO2 has complex band structure (e.g., indirect transition gap and nonparabolic bands). The magnitude of the theoretical impact ionization rate was very close to the experimental results recently reported by E. Cartier and F.R. McFeely [Phys. Rev. B 44, 10689 (1991)]. Detailed theoretical study clearly demonstrates that the average energy of secondary generated carriers depends linearly on the energy of primary electrons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354959
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  • 2
    Electronic Resource
    Electronic Resource
    Impact ionization model for full band Monte Carlo simulation (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 3500-3506 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The impact ionization rate in silicon is numerically derived from wave functions and energy band structure based on an empirical pseudopotential method. The calculated impact ionization rate is well fitted to an analytical formula with a power exponent of 4.6, indicating soft threshold of impact ionization rate, which originates from the complexity of the Si band structure. The calculated impact ionization rate shows strong anisotropy at low electron energy (cursive-epsilon〈3 eV), while it becomes isotropic at higher energy. Numerical calculation also reveals that the average energy of secondary generated carriers depends linearly on the primary electron energy at the moment of their generation. A full band Monte Carlo simulation using the newly derived impact ionization rate demonstrates that calculated quantum yield and ionization coefficient agree well with reported experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356112
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  • 3
    Electronic Resource
    Electronic Resource
    Micromagnetic computation for wall and Bloch line coercivity in thin films with perpendicular anisotropy : 38th Annual Conference on Magnetism and Magnetic Materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 6089-6091 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Wall and vertical Bloch line (VBL) coercivity arising from spatial nonuniformity in the material parameters has been investigated for a typical 5-μm bubble garnet film by means of a two-dimensional micromagnetic computation. Two-dimensional sinusoidal modulations in the magnitude of the uniaxial anisotropy were assumed as a model for a compositional nonuniformity. Nonuniformities with a spatial wavelength comparable to the wall width were found to exert the largest pinning effect. The typical computed value for the wall and VBL coercivity were 0.7 and 2.2 Oe, respectively, where 10% variation and wavelength of 0.47 μm were assumed. The tendency, that the VBL coercivity is larger than that for the domain wall, agrees with the experimental results reported previously. The wall and VBL coercivity caused by a nonuniform exchange constant have also been computed and compared to the analytical solutions due to the step-like variation of wall and VBL energies, respectively. The larger VBL coercivity compared to that for the wall was observed for a local modulation with the size less than wall width and period more than 1 μm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355468
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  • 4
    Electronic Resource
    Electronic Resource
    Successive Bloch line write operation in a 1-μM bubble material : 38th Annual Conference on Magnetism and Magnetic Materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 6086-6088 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The successive vertical Bloch line (VBL) write operation has been performed in an as-grown 1-μm bubble material with a flank wall writing scheme. An unwinding VBL pair was nucleated by a domain expanding pulse current (200-mA amplitude, 200-ns pulse width, 8-ns rising edge) applied through a hair-pin type conductor (gap:2.6 μm, width:4 μm). The VBL position was controlled by a local in-plane magnetic field produced by a conductor current of 30 mA and a uniform in-plane magnetic field of 10 Oe. The above operating parameters were adjusted by measuring the collapse field of the stripe domain as a function of the parameters. The increase of bubble collapse field from 442 to 513 Oe in accordance with the number of write operations indicated a successful write operation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355467
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  • 5
    Electronic Resource
    Electronic Resource
    Characterization of x rays emitted from 351-nm laser-produced plasmas for x-ray shadowgraphy (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 2693-2699 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: X-ray conversion efficiencies in 351-nm laser-produced plasmas are investigated. X-ray line emissions, which are useful for x-ray shadowgraphy, have been characterized by studying dependencies on laser pulse duration, irradiation intensity, target material, and target structure. The conversion efficiencies decrease with increasing x-ray energy and markedly decrease with increasing laser intensity. A microparticle on a plastic plate is tested in an attempt to develop a point x-ray source. This target shows a higher conversion rate than a microwire target due to reduction in energy dissipation through hydrodynamic expansion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.345486
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  • 6
    Electronic Resource
    Electronic Resource
    A Monte Carlo simulation of anisotropic electron transport in silicon including full band structure and anisotropic impact-ionization model (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 297-312 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The physics of electron transport in bulk silicon is investigated by using a newly developed Monte Carlo simulator which improves the state-of-the-art treatment of hot carrier transport. (1) The full band structure of the semiconductor was computed by using an empirical-pseudopotential method. (2) A phonon dispersion curve was obtained from an adiabatic bond-charge model. (3) Electron-phonon scattering was computed by using a rigid pseudo-ion model. The calculated scattering rate is consistent with the full band structure and the phonon dispersion curve of silicon, thus leaving no adjustable parameters such as deformation potential coefficients. (4) The impact-ionization rate was calculated by using Fermi's golden rule directly from the full band structure. We took into account the dielectric function depending on both wave vector and transition energy in the numerical calculation of the rate. The impact-ionization rate obtained in the present study strongly depends on both wave vector and band index of the conduction electron, which is ignored by the traditional Keldysh formula. (5) In the simulator, the final state of a scattering electron is determined in such a way as to conserve both energy and momentum in scattering processes. The simulated results, under the steady-state conditions as well as under the nonequilibrium conditions, are presented and compared with experimental results. Special attention is focused on anisotropic transport during velocity overshoot. Quantitative agreement between calculated and experimental results confirms the validity of the newly developed Monte Carlo simulator and the physical models that were used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355849
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  • 7
    Electronic Resource
    Electronic Resource
    Density relaxation of silicon dioxide on (100) silicon during thermal annealing (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 2195-2198 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Measurements of the refractive index of thermally grown oxide after annealing reveal that the density relaxation of the oxide is well described by a stretched exponential decay function. The experiments of two-step oxidation show that oxygen diffusivity in the oxide exponentially decreases with the oxide density. The relation between the oxide density and the refractive index is well expressed by a simple power relation rather than the Lorenz–Lorenz formula.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.345563
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  • 8
    Electronic Resource
    Electronic Resource
    Unusual human rotavirus strains having subgroup I specificity and “long” RNA electropherotype (1989)
    Springer
    Archives of virology 109 (1989), S. 11-23 
    Details
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary During an epidemiological study of human rotavirus in Metro Manila, Philippines, we found 20 unusual strains which belong to subgroup I but have “long” RNA pattern typical of subgroup II human rotavirus. The RNA patterns of the 20 strains were classified into four groups though they were very similar to each other. Four strains, designated L4, L26, L27, and L34 were isolated in MA 104 cells from stool specimens. They possessed subgroup I specificity and long RNA pattern identical to that of the viruses in the original stool samples. The serotype specificity of these strains could not be determined by either enzyme-linked immunosorbent assay (ELISA) or neutralization test, while one strain (L27) was neutralized by serotype 2-specific anti-VP4 monoclonal antibody. These strains were suggested to have an unusual antigenicity on VP7.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01310514
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  • 9
    Electronic Resource
    Electronic Resource
    BCG induced killer cell activity (1988)
    Springer
    Urological research 16 (1988), S. 351-355 
    Details
    ISSN: 1434-0879
    Keywords: Intravesical BCG ; Peripheral blood mononuclear cells ; Killer activity against natural killer cell (NK) resistant tumors, NK type precursor and effector cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To investigate the mechanism of Bacillus de Calmette Guérin (BCG) bladder instillation therapy, the killer cell activity induced in peripheral blood mononuclear cells (PBMNCs) after BCG instillation was examined. Significant cytotoxic activity against natural killer (NK) cell resistant target tumor cells was detected after 3 days of instillation. To characterize this BCG induced cytotoxic activity further, human PBMNCs were cultured with BCG in vitro. From 24 h maximum cytotoxicity was obtained and continued for 3 days, then decreased slightly. Neither a DNA synthesis inhibitor Cytosine-arabinoside (Ara-C) nor a cytotoxic T cell (CTL) generation inhibitor Cyclosporine A inhibited this killer cell activation. Monoclonal antibody treatment revealed that both precursor and effector cells are Leu1-, 3a-, 7+, 11b+. The recognition specificity from cold target competition experiments was selective. Taken together NK type precursor was activated with BCG into NK type effector which has wider spectrum of target cells than usual NK cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00256041
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  • 10
    Electronic Resource
    Electronic Resource
    Presumptive seventh serotype of human rotavirus (1990)
    Springer
    Archives of virology 113 (1990), S. 279-282 
    Details
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Four group A human rotaviruses having antigenic specificity of subgroup I and ‘long’ RNA electropherotype were isolated in MA104 cell cultures. Cross-neutralization tests with hyperimmune antisera suggested that they are serologically distinct from the six previously recognized human rotavirus serotypes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01316680
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