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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 86 (1993), S. 36-41 
    ISSN: 1432-0533
    Keywords: Alzheimer's disease ; β/A4 deposits ; Morphological types ; Spatial pattern ; Clustering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The spatial patterns of diffuse, primitive, classic (cored) and compact (burnt-out) subtypes of β/A4 deposits were studied in coronal sections of the frontal lobe and hippocampus, including the adjacent gyri, in nine cases of Alzheimer's disease (AD). If the more mature deposits were derived from the diffuse deposits then there should be a close association between their spatial patterns in a brain region. In the majority of tissues examined, all deposit subtypes occurred in clusters which varied in dimension from 200 to 6400 μm. In many tissues, the clusters appeared to be regularly spaced parallel to the pia or alveus. The mean dimension of the primitive deposit clusters was greater than those of the diffuse, classic and compact types. In about 60% of cortical tissues examined, the clusters of primitive and diffuse deposits were not in phase, i.e. they alternated along the cortical strip. Clusters of classic deposits appeared to be distributed independently of the diffuse deposit clusters. Cluster size of the primitive deposits was positively correlated with the density of the primitive deposits in a tissue but no such relationship could be detected for the diffuse deposits. This study suggested that there was a complex relationship between the clusters of the different subtypes of β/A4 deposits. If the diffuse deposits do give rise to the primitive and classic varieties then factors unrelated to the initial deposition of β/A4 in the form of diffuse plaques were important in the formation of the mature deposits.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 46 (1994), S. 209-213 
    ISSN: 1432-1041
    Keywords: Insomnia ; Temazepam ; elderly ; efficacy ; tolerance ; intermittent administration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Temazepam, 7.5 mg was evaluated in the sleep laboratory in 8 elderly insomniacs, using a 14-night protocol (4 placebo-baseline nights, 7 drug nights, and 3 placebo-withdrawal nights). With short-term use temazepam was found to be effective, producing a significant improvement in total wake time from baseline (100 vs. 145 min). With continued drug administration, total wake time remained below baseline but not significantly so (125 vs. 145 min). During drug administration, there were no major CNS and behavioral adverse effects reported such as daytime sedation, memory impairment or hyperexcitability (daytime anxiety). Following drug withdrawal, there was no significant increase in wakefulness, i.e., no rebound insomnia (150 vs. 145 min). In summary, temazepam, 7.5 mg is effective in elderly subjects with short-term use and has a minimum of adverse effects. Use of hypnotic drugs is an adjunctive therapy which should be for a short-term period with subsequent short-term intermittent use as needed. Because of its low propensity for producing rebound insomnia, temazepam can be effectively used in this manner.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 9122-9127 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Vaporization reactions for both Tl2O3(s) and a Tl superconductor sample, primarily Tl2Ba2Ca2Cu3Oy(s) (Tl-2223), were determined. The vapor species were examined by Knudsen effusion mass spectrometry at temperatures in the range 657 to 773 K for Tl2O3(s) and 672 to 836 K for Tl-2223. Additional experiments with thermogravimetric analysis (TGA) equipment were performed. In both cases of vaporization of Tl2O3 and Tl-2223, the vapor species were concluded to be Tl2O(g) and O2(g). Vapor pressures were measured. For Tl2O3(s), ΔvapH0 (298.15 K) was measured as 320.4±6 kJ/mol. The activity of Tl2O3 in the Tl-2223 superconductor was measured as 0.0044±0.001 at 750 K. A measure of the stabilization of Tl2O3 in the Tl-2223 superconductor is given by μ(Tl2O3,sc)−μ(Tl2O3,pure)=−33.84±3.0 kJ/mol.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High concentrations of recombination-promoting impurities in the near-surface region of a semiconductor can produce virtually complete suppression of carrier-driven photochemical etching processes. In-diffusion of Zn to levels appropriate for ohmic contact formation on GaAs (mid-1020/cm3) has been employed to reduce etching to an undetectable level in n-GaAs with n=1.0×1017 and 1.3×1018/cm3 and to produce a greater than ten-fold reduction in etching of semi-insulating GaAs. Raman spectroscopy of the altered near-surface region shows enhanced electronic scattering, which indicates the presence of a sufficient impurity concentration to suppress etching. Transmission electron microscopy shows the near-surface region to be crystalline without significant numbers of defects following Zn diffusion. Possible applications of this process include self-aligned etching of transistor and laser structures.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 5313-5317 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The vapor pressures of Cu in equilibrium with YBa2Cu3O6.24 were measured as a function of temperature by the Knudsen effusion method using a quadrupole mass spectrometer as the detector. The data were fitted to ln [P(Cu)/bar]=(−66104±4485)(1/T)+(35.360±3.869). The activity of Cu [in YBa2Cu3O6.24(s) ] was calculated as the ratio of the above equilibrium pressure divided by the vapor pressure of pure Cu(s). From the activities, relative chemical potentials were calculated. The vapor pressure of Cu from the superconductor intersects the vapor pressure of Cu from pure Cu(s) at 1290±20 K, which indicates that the superconductor decomposes to metallic Cu at temperatures greater than 1290 K.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 494-496 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present results on the first all-semiconductor, vertical Fabry–Perot-cavity optical transmission modulator. This device combined mechanically stable strained and unstrained (In,Al,Ga)As multilayers to achieve operation at 1.06 μm. Transmission-mode operation allows the resonant wavelength of the cavity to be finely tuned by varying the angle of incidence, providing, for the first time, a means of compensating for small inaccuracies in growth parameters. Using the modulator in double-pass operation with a corner-cube retroreflector, we demonstrate a tunable reflectance modulator with a fractional modulation of 25% at 3-V bias, suitable for applications in free-space communication.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 1945-1947 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report dramatic improvements to the implanted-planar buried-heterostructure graded-index separate confinement heterostructure (IPBH-GRINSCH) laser in (AlGa)As/GaAs which produces low threshold current, continuous-wave operation. Our process features significantly reduced fabrication complexity of high quality, index-guided laser diodes compared to regrowth techniques and, in contrast to diffusion-induced disordering, allows creation of self-aligned, buried, blocking junctions by ion implantation. The improved single-stripe IPBH-GRINSCH lasers exhibit 39 mA threshold current, cw operation.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 1521-1523 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report measurements of the injection-locking characteristics of a high-power continuous-wave diode laser array with an on-chip independently controlled master laser. This integrated injection-locked array emits a near-diffraction-limited single-lobed output beam at cw power levels up to 220 mW/facet. By controlling the current to the master laser, the single-lobed output beam can be electronically steered over a far-field angle of 〉1.7°. We also report preliminary studies of the coupling interaction in these integrated devices.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 2648-2650 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The first experimental demonstration of a surface-normal bistable optical switching device based on the monolithic integration of a vertical-cavity surface-emitting laser and a pnpn photothyristor is reported. By the use of ion implantation, it is shown that the positive feedback in the photothyristor can be controlled, thus enabling the integration of both bistable and latching optical switches on the same epitaxial structure. High contrast (30 dB) and an optical gain of 8 are demonstrated.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 2886-2888 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The production of a near-diffraction-limited single-lobed angle-switchable output beam from a broad-area diode laser with an intracavity spatial phase controller is demonstrated. This 100-μm-wide broad-area laser produces a 0.8° full width at half maximum output beam at single-facet pulsed powers of (approximately-greater-than)300 mW. The spatial phase controller operates in two distinct modes (thermal and gain), providing beam scanning over 1.4° and beam switching of 8°. The phase controller also permits a dynamic study of the effect of wavefront tilt on device coupling and phasing.
    Type of Medium: Electronic Resource
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