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  • 1
    Electronic Resource
    Electronic Resource
    Two-dimensional mapping of the plasma density in the upper atmosphere with computerized ionospheric tomography (CIT) : The 39th annual meeting of division of plasma physics of APS (1998)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 5 (1998), S. 2010-2021 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Tomographic imaging of the ionosphere is a recently developed technique that uses integrated measurements and computer reconstructions to determine electron densities. The integral of electron density along vertical or oblique paths is obtained with radio transmissions from low-earth-orbiting (LEO) satellite transmitters to a chain of receivers on the earth's surface. Similar measurements along horizontal paths can be made using transmissions from Global Position System (GPS) navigation satellites to GPS receivers on LEO spacecraft. Also, the intensities of extreme ultraviolet (EUV) emissions can be measured with orbiting spectrometers. These intensities are directly related to the integral of the oxygen ion and electron densities along the instrument line of sight. Two-dimensional maps of the ionospheric plasma are produced by analyzing the combined radio and EUV data using computerized ionospheric tomography (CIT). Difficulties associated with CIT arise from the nonuniqueness of the reconstructions, owing to limited angle measurements or nonoptimal receiver location. Improvements in both reconstruction algorithms and CIT measurement systems are being implemented to overcome these difficulties. New imaging systems being developed employ CIT for large area mapping of the plasma densities in the ionosphere. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.872872
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  • 2
    Electronic Resource
    Electronic Resource
    Optical and structural studies of the effect of spacers in modulation-doped ZnSe/Zn1−xCdxSe quantum wells (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 891-895 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of spacers in modulation-doped Zn1−xCdxSe/ZnSe:Cl multiple quantum wells (MD-MQWs) was investigated by photoluminescence (PL) and time-of-flight secondary-ion-mass spectrometry (TOF-SIMS). A comparison was made between structures with and without spacers as a function of annealing temperature. The diffusion of Cl and Cd was monitored by TOF-SIMS depth profiling and photoluminescence. Although TOF-SIMS does not show any significant diffusion of Cl and Cd in both structures at temperatures up to 385 °C, the PL results indicate the modification of optical properties in the Zn1−xCdxSe/ZnSe:Cl MD-MQWs due to annealing. Up to an annealing temperature of 385 °C, the MD-MQWs with spacers show superior optical quality in the quantum well regions, while quenching of the quantum well band-edge PL and strong enhancement of deep-level emission were observed from the MD-MQWs without spacers. This phenomenon suggests that the radiative deep-level emission may provide more efficient channel for electron–hole recombination with increasing annealing temperature. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.370863
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  • 3
    Electronic Resource
    Electronic Resource
    A frequency modulated mm-wave interferometer with a single sideband upconverter (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2516-2519 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A frequency modulated interferometer is developed, which uses a 94 GHz Gunn oscillator and a single sideband (SSB) upconverter as a frequency modulator. An SSB upconverter makes it possible to use a heterodyne phase measurement technique with one mm-wave source. In addition, the influence of frequency drift and phase noise of a mm-wave source on the phase measurement can be reduced. In this work, the performance of a SSB upconverter as a frequency modulator is examined. Also, overall performance of the mm-wave interferometer with a SSB upconverter and line density measurement results in a mirror device are described. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149784
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  • 4
    Electronic Resource
    Electronic Resource
    Angle chord integral inverter and a rotating type optical probe (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1730-1734 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The inversion problem of angle dependent chord integrals is theoretically studied and a rotating type optical probe is developed for its application. The proposed solution is computationally efficient and robust to measurement additive noise. The probe system constructed is tested in an inductively coupled plasma source by measuring a spectral line intensity of argon plasma. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149659
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  • 5
    Electronic Resource
    Electronic Resource
    Overview of Korea Superconducting Tokamak Advanced Research diagnostics (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1397-1401 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The Korea Superconducting Tokamak Advanced Research (KSTAR) project is the Korean national fusion program for constructing a superconducting tokamak, that is capable of a steady-state operation. Currently, the KSTAR diagnostic group is concentrating on conceptual design activities to provide measurements of the plasma behavior that is necessary to satisfy the KSTAR missions. A diagnostic overview for the KSTAR device is presented. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149631
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  • 6
    Electronic Resource
    Electronic Resource
    A chamber for laboratory studies of atmospheric aerosols and clouds (1996)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 4364-4368 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A stainless-steel chamber has been constructed and interfaced to a Fourier transform infrared spectrometer for the purpose of studying laboratory simulated atmospheric aerosols and clouds. The chamber is cylindrical in design and is comprised of a double-walled inner assembly that resides within an outer vacuum jacket. The volume of the aerosol sample region is 28 L. By circulating refrigerated methanol between the double walls of the inner assembly, constant temperature control of the sample region can be maintained between 187 and 300 K. A study of temperature uniformity within the chamber at 291, 240, and 187 K revealed a standard deviation in temperature of 1.6 K as determined from measurements made using five copper–constantan thermocouples. Good agreement is obtained between thermocouple measured temperatures and rotational temperatures computed from infrared absorption spectra of methane gas. The chamber described here has been used to examine heterogeneous chemistry of solid powder samples. A technique of generating an aerosol sample by rapidly dispersing a solid powder in a gas is presented. The half-life of a γ-alumina aerosol sample was measured to be 25 min. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1147537
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  • 7
    Electronic Resource
    Electronic Resource
    Staurosporine-Induced Activation of Caspase-3 Is Potentiated by Presenilin 1 Familial Alzheimer's Disease Mutations in Human Neuroglioma Cells (1999)
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 73 (1999), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract : Familial Alzheimer's disease (FAD) mutant forms of presenilin 1 (PS1) and 2 have been shown to sensitize cells to apoptotic cell death. Here we explore the effects of FAD mutant forms of PS1 on caspase activation during apoptosis. We show that caspase activation leads to increased generation of alternative C-terminal fragments (CTFs) from mutant as compared to wild-type (wt) PS1. For this purpose, very low expression levels of wt, A246E, L286V, and ΔE10 FAD mutant PS1 proteins in stably transfected human H4 neuroglioma cells were used to avoid artifactual induction of spontaneous apoptosis due to overexpression of PS1. Staurosporine treatment of these cells resulted in increased cell death and up to a 10-fold increase in caspase-3 activation in mutant versus wt PS1-expressing cell lines. Correspondingly, relative levels of caspase-cleaved PS1 CTFs were increased by five-to sixfold in the FAD mutant versus wt PS1 cells. Elevated caspase activation and caspase cleavage of FAD mutant PS1 suggest the possibility of either a direct proapoptotic effect of mutant PS1 or interference of mutant PS1 with antiapoptotic effects of wt PS1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1999.0732278.x
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  • 8
    Electronic Resource
    Electronic Resource
    Fabrication and magnetic properties of metal/cobalt ferrite composite thin films : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 4893-4895 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: To improve the saturation magnetization (Ms) of cobalt ferrite thin films, metal/cobalt ferrite composite thin films were prepared by controlling the sputtering conditions such as oxygen concentration in sputtering gas, substrate temperature, composition of the thin films. With decreasing the oxygen ratio from 50% to 5% in sputtering gas and increasing the substrate temperature from room temperature to 400 °C, the Ms of the thin films was increased and the coercivity (Hc) decreased. The result was attributed to deposition of the metal/cobalt ferrite thin films. With increasing the metal ratio in the thin films, preferred orientation of (111) of cobalt ferrite was worsened in the thin films. The metal deposited in the thin films was identified as cobalt with (002) preferred orientation. In higher cobalt content than the stoichiometric composition of CoFe2O4, the thin films with high Ms and Hc could be deposited in the wide substrate temperature range of 200–400 °C. We can prepare the metal/cobalt ferrite composite thin films with Ms about 580 emu/cm3 and Hc 1700 Oe by controlled the sputtering conditions. The thin films are thought to be applicable to the magnetic recording media with high recording density. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361642
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  • 9
    Electronic Resource
    Electronic Resource
    Photoluminescence of nanocrystallites embedded in hydrogenated amorphous silicon films (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 6193-6196 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have fabricated light-emitting nanocrystallites embedded in an a-Si:H matrix using a conventional plasma-enhanced chemical-vapor-deposition system. It was found that the photoluminescence properties are directly related to the deposition parameters. The quantum size effect model is proposed to explain the photoluminescence. Two structural prerequisites are proposed for this kind of films to exhibit effective light emission: One is an upper limit for mean crystallite size of about 3.4 nm, the other is an upper limit for crystallinity of about 30%. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360778
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  • 10
    Electronic Resource
    Electronic Resource
    Effects of phosphorous doping on the stability of coercivity of cobalt-substituted acicular oxides (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 409-412 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of P doping on the coercivity and magnetic-thermal stability of Co-substituted iron oxides have been investigated by means of magnetic measurements, torque curves, and Mössbauer spectra. It is found that the P doping of cobalt-substituted acicular oxides promotes the coercivity and the stability with temperature of the coercivity. Then effects may be attributed to the increase of the cubic magnetocrystalline anisotropy constant K1 and the activation energy E, respectively. The Mössbauer results suggest that P ions are located in the neighborhood of the B-site Fe ions. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360617
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