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  • 1
    ISSN: 1432-0533
    Keywords: Glioma ; Collagen ; Extracellular matrix ; Glycoprotein ; Mesenchyme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We established and characterized five cell lines derived from human malignant gliomas (four glioblastomas multiforme and one highly anaplastic astrocytoma). All cell lines exhibited tumor cell morphology and growth kinetics, and anchorage-independent growth in soft agar. Cytogenetic analysis revealed significant aneuploidy in all five cases as well as clonal chromosomal alterations unique to each cell line. No cell line was tumorigenic in athymic mice. Two of the cell lines were sensitive to carmustine (BCNU) in monolayer and soft-agar cultures. Electron microscopy showed marked variability between cell lines in the number and structure of intracytoplasmic organelles; SF-126 formed collagen fibers in vitro. Immunohistochemical analysis of the surgical specimens showed variable expression of glial fibrillary acidic protein (GFAP) in malignant astrocytes; positive immunostaining for glycoproteins of the extracellular matrix was found predominantly in perivascular regions. In early-passage cultures, only cell line SF-295 expressed GFAP; at establishment, none of the cell lines expressed GFAF or glutamine synthetase. Fibronectin and laminin were expressed by all cell lines in early-passage culture, but expression of these glycoproteins at establishment was variable. Only SF-126 was positively identified by immunostains for procollagen III; this was also the only cell line in which DEAE-cellulose chromatography and SDS-PAGE demonstrated interstitial collagen synthesis. These well-characterized glioma-derived cell lines may now serve as useful tools with which to study the cell biology of gliomas. The synthesis of interstitial collagen by a glioma-derived cell line may suggest a derivation from vascular mesenchymal elements, either reactive or transformed, in the original heterogeneous malignant glioma, rather than from a glial precursor cell.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1459
    Keywords: Key words Parkinson’s disease ; Depression ; Functional activities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We evaluated 109 Chinese patients with Parkinson’s disease (PD) in three ways: using a standardized psychiatric interview for depression and anxiety, using standardized neurological evaluation for motor disability, and using cognitive assessment for cognitive impairment. Six of the 109 patients who had dementia and another two afflicted with organic delusional disorder were excluded from further analysis. The remaining 101 PD patients were divided into the following three groups according to the DSM-III-R criteria: major depressive disorder (n = 18), other depressive disorders (n = 25) including dysthymic disorder and depressive disorder not otherwise specified, and no depression (n = 58). The frequency of major depressive disorder of the 109 PD patients was 16.5%, and the frequency of major and other depressive disorders, taken together, was 42.2%. Using the percentage points measured on the Schwab & England Activites of Daily Living Scale as the dependent variable to fit a multivariate regression model, we found the lower score significantly correlated with the diagnosis of depressive disorder and higher score of the Hamilton Depression Rating Scale, in addition to motor disability and disease severity of PD. Given the high frequency of depression and the significant correlation between depression and performance in daily functional activites, we believe that an evaluation of PD patients for coexisting depression is necessary for a better therapeutic outcome.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Optics and Lasers in Engineering 11 (1989), S. 185-215 
    ISSN: 0143-8166
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Electrical Engineering, Measurement and Control Technology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics , Technology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 4792-4794 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Circuit simulations of resonant tunneling double-barrier diodes (DBD) are reported. Small signal equivalent circuit considerations predict whether a circuit is stable when a DBD is biased in the negative differential resistance (NDR) region, and also predict the nature of an oscillation (sinusoidal-like or exponential) if unstable. Large signal analyses give the temporal behavior of an oscillation. The nonlinear differential equation is solved by a piecewise linear model to a high accuracy. Oscillations give rise to an apparent plateaulike structure or even a peak structure in the NDR region when measuring the dc current-voltage characteristic.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 3458-3463 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The occurrence of stress in thin films has led to serious considerations of stability problems in the semiconductor industry. It may cause mechanical failure of films, such as adhesion reduction or contact peel-off, or variations in electrical properties. The existence of stress will also alter electromigration behavior for thin metal lines. The elastic stress in a multilayered structure due to thermal processing is calculated by use of the principle of mechanics balance. It is found that the variation of thickness in one film will not affect the magnitude of stress in another film. The shearing and peeling stress at the edge of a patterned structure, which is responsible for the peeling of a film at the edge, is then modeled and discussed in detail. Finally, the relaxation of stress by viscous motion of SiO2 is analyzed based on Maxwell's viscoelastic model.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 1062-1064 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present the results of a systematic study of a series of intersubband multiple quantum well detector samples having 4, 8, 16, and 32 wells. We find that while the absorption increases with the number of wells in the device, the detector current responsivity is insensitive to the number of wells.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A low dark current dual band quantum well infrared photodetector is demonstrated by adding thin AlAs barriers to the usual detector structure, which consists of Si-doped GaAs wells separated by thick AlGaAs barriers. The advantages of adding the thin AlAs barriers to clad the quantum wells are that (a) the detector displays a low dark current and (b) intersubband photocurrents result from transitions from both the Γ ground to the first excited state, and from the Γ ground to a mixed Γ-X excited state because the X-valley band edge forms a well in AlAs and intrinsic Γ-X mixing occurs. The spectral peaks of these two transitions, which occur at 8.5 and 5.5 μm in our test structure, can be varied by changing device parameters during growth.
    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 79 (1996), S. 3307-3311 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe a 9 μm AlGaAs/GaAs asymmetric quantum well infrared photodetector with voltage tunable spectral bandwidth. A very narrow spectral response of 9.2 meV (0.6 μm) full width half maximum is observed for an applied electric field of 28 kV/cm. The linewidth quadruples when the bias polarity is reversed, with very little shift in the peak detection wavelength. This structure is based on a conventional intersubband photodetector modified by using AlGaAs barriers that are graded in Al content and by adding a thin AlGaAs confinement layer on one side of the well. The asymmetry in the barriers is shown to give rise to the dependence of the spectral linewidth on applied bias. As well, a series of unusually well-resolved and intense bound-to-continuum transitions are observed at low bias, that may indicate that the unique barrier shape also leads to enhanced electron interference effects at the well/barrier interfaces.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 8091-8097 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A systematic study of stacked quantum well infrared photodetectors is undertaken to improve the understanding of the voltage-tunable multi-color spectral response. The multi-color capability is achieved by sequentially growing conventional one color detectors, separated by conducting layers. The behavior of the stacked devices is proven to correspond to the individual detectors simply acting in series with each other. The dc resistance, photocurrent and dynamic resistance characteristics of the individual detectors are examined and correlated with the voltage-tuning in the stack. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 8234-8236 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The peak detection wavelength of an operational quantum-well infrared photodetector structure has been red shifted using rapid thermal annealing to partially intermix the well and barrier layers. Successive anneals at 850 °C were used to tune an 8.13 μm detector continuously out to 9.13 μm. All of the fabricated detectors were operational in spite of very long annealing times of up to 300 s. The peak spectral responsivity at a device current of 10 μA dropped from 0.62 to 0.12 A/W after the longest anneal time, but the broadband responsivity only dropped by a factor of 3 due to a simultaneous increase in the detection spectral bandwidth.
    Type of Medium: Electronic Resource
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