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  • 1985-1989  (18)
  • 1975-1979
  • 1987  (18)
  • 1
    Electronic Resource
    Electronic Resource
    Photo-Hall determination of acceptor densities in n-type HgCdTe (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 1047-1054 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A comprehensive photo-Hall investigation of compensation densities in n-type Hg1−xCdxTe (0.224〈x〈0.235) is reported. The technique consists of measuring the low-temperature electron mobility as a function of optically excited carrier density. Pulses of 25-μs duration from a CO2 laser yield excess electron-hole plasma densities of between 1013 and 1016 cm−3. At low excitation levels the mobility increases due to the neutralization of ionized acceptors by photoexcited holes, while at higher excitation levels the mobility slowly decreases due to electron-hole scattering. By comparing to a detailed theory for electron transport in photoexcited narrow-gap semiconductors, the density of compensating acceptors NA can be accurately determined. The theory is generalized to account for multi-ion scattering, carrier heating, surface conduction, and inhomogeneous excitation. Experimental refinements significantly extending the range of narrow-gap n-type samples for which compensation densities may be determined are discussed. The present study demonstrates the broad applicability of the technique by determining NA for samples with compensation ratios between 0.09 and 0.96 and with both single and double acceptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.338196
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  • 2
    Electronic Resource
    Electronic Resource
    Synchronizable, injection-locked, Q-switched, mode-locked, and cavity-dumped ten-atmosphere CO2 laser (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 843-851 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A novel, active, mode-locking scheme for producing single, line-tunable, high-power ultrashort CO2-laser pulses is described. Using an auxiliary grating-tuned cw CO2 laser for injection locking on the 9R(16) line, the Q-switched, mode-locked, and cavity-dumped 10-atm CO2 laser produces single, detection-limited (〈500 ps) pulses of 5-mJ energy at λ=9.29 μm. Details are given on the traveling-wave GaAs Pockels cells, both of which are controlled by a single, ultraviolet (UV) triggered spark gap. The time-locked output pulse is delayed by precisely 300.7 ns with 〈±50 ps jitter against the UV triggered spark gap, so the laser pulse is synchronizable to an external event to 〈±250 ps. To drive the transverse-electric (TE) 10-atm amplifier section, instead of the conventional Marx bank or inductance-capacitance (LC) generator, a new type of circuit is used. The automatically preionized, double-sided LC inversion circuit uses only one spark gap, and a detailed description with operating characteristics is provided.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.338133
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    High gain, multiatmosphere CO2 laser amplifier (1987)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 58 (1987), S. 261-264 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A novel TE discharge, 15-mm aperture, multiatmosphere, CO2 laser amplifier is described, with measured electrical characteristics and gain measurements on the 9.294-μm, 9R(16) line. The electrical circuit used in this amplifier is a realistic alternative to the Marx bank or conventional LC inversion circuit and, similarly, it would be useful for excitation of other gas lasers as well. This automatically preionized, double-sided, fourfold LC inversion circuit uses only one spark gap, and it is shown to provide small-signal gains of 5.7% cm−1, at 120 J l−1 atm−1 and 10 atm. The generalization to an n–stage device, which would be suitable for higher pressures, and larger apertures, is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139318
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  • 4
    Electronic Resource
    Electronic Resource
    Metabolism of a sub-tropical low gradient black water river (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 17 (1987), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. 1. Single-station diel oxygen curves were used to monitor the oxygen metabolism of the Ogeechee River, a sixth-order blackwater river in the Coastal Plain of southeastern U.S.A., over a period of 4 years. Ecosystem production (P) and respiration (R) were estimated, and P/R ratios calculated to determine the extent of autotrophy characteristic of this type of river. The potential error in oxygen metabolism caused by photo-oxidation of dissolved organic carbon (DOC) in the water was measured and found to be minor.2. Rates of ecosystem primary production measured were intermediate compared to other rivers, ranging from 0.49 to 13.99g O2m−2 day −1.Primary production rates were highest during the summer when water levels were low. Regression analysis indicated that water depth and light absorption by DOM were significant predictors of primary production in this river. Incident light intensities were not significantly correlated with production rate.3. Respiration rates were unusually high, varying between 3.70 and 11.5 g O2 m−2 day − 1. System respiration also varied seasonally, but less than primary production. Rates were slightly higher in spring and summer.4. With one exception, P/R ratios were considerably lower than l throughout the study period, indicating that the Ogeechee River was highly heterotrophic. PIR ratios ranged from 0.09 to 1.3, and averaged 0.25.5. A carbon budget calculated for this river showed floodplain inputs were 7 times autochthonous production. Organic carbon turnover length was 690 km, considerably longer than has been reported for lower-order rivers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1987.tb01046.x
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  • 5
    Electronic Resource
    Electronic Resource
    Lymphotoxin-Induced Growth Stimulation of Diploid Human Fibroblasts in the Presence and Absence of Gamma Interferon (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of immunology 26 (1987), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In the present study we investigated the effect of lymphotoxin (LT) on the growth of human diploid fibroblasts, in the presence and absence of gamma interferon (IFN-γ). Recombinant LT (rLT) had a growth stimulatory effect on diploid human FS-4 fibroblasts. This growth-stimulatory effect was reduced in the presence of recombinant IFN-γ (rIFN-γ). LT thus has a similar effect on diploid fibroblasts as tumour necrosis factor (TNF).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3083.1987.tb02293.x
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  • 6
    Electronic Resource
    Electronic Resource
    Fibroblast Growth-Stimulatory Activity Released from Human Monocytes (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of immunology 26 (1987), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Human monoeytcs release fibroblast growth-stimulatory activity. In this study tumour necrosis factor (TNF) has been identified as a major contributor to the monocyte-derived fibroblast growth-stimulaiory activity. A neutralizing monoclonal antibody (MoAb) against recombinant TNF (rTNF) inhibited growth of FS-4 fibroblasts and skin biopsy fibroblasts induced by monocyte supernatants, indicating that TNF was involved in the stimulation. Optimal growth of FS-4 fibroblasts was induced by monocyte supernatants at dilutions which cointained TNF at a concentration between 1.6 × 10−6 and 4.0 × 10−5μg/ml, less growth being induced at higher TNF concentrations. Contrary to this, no optimal concentration interval was found lor rTNF, since increasing rTNF concentrations always resulted in increased growth stimulation. It also appeared that natural TNF in the monocyte supernatants induced growth at a much lower concentration than rTNF tested in the absence of monocyte supernatant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3083.1987.tb02297.x
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  • 7
    Electronic Resource
    Electronic Resource
    Second harmonic emission from an underdense laser-produced plasma and filamentation (1987)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 30 (1987), S. 890-895 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is shown theoretically that filamentation can lead to sizable second harmonic generation. The 2ω0 radiation is emitted into a forward-directed cone, its angle determined by the wavelength of the fundamental radiation in the plasma waveguide. Experimental observations confirm the theoretical predictions. Aside from the forward-directed emission cone, non-negligible 2ω0 power is detected over a broad angular range in the backward direction showing a broadened red-shifted spectrum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.866342
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  • 8
    Electronic Resource
    Electronic Resource
    Monocyte-Derived Influence on Growth of Normal Human Fibroblasts (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of immunology 26 (1987), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The current study demonstrates that whereas high concentrations of recombinant tumour necrosis factor (rTNF. 0.05/(g/ml) induced enhanced growth of normal human fibroblasts, supernatants from human monoeytes with u similar TNF concentration induced cytostasis. This cytoslasis was inhibited by an antiserum against rTNF. The TNF activity, measured as cytotoxicity against TNF-sensitive WEHI 164 cells, cochromatographed with the fibroblast growth inhibitory activity upon ion-exchange chromatography of monocyte supernatants. This indicates that TNF contributes to the fibroblast growth inhibition mediated by monocyte supernatants. Alpha inierfcron (IFN-α) abolished the growth of fibroblasts induced by rTNF, whereas rTNF in combination with gamma interferon (IFN-α) inhibited growth of fibroblasts. The interferon activity in the supernatants was determined to find out whether the growth inhibitory activity of natural TNF was due to interferons present in the monocyte supernatants. which might modulate the TNF activity. Cytostasis of fibroblasts was mediated by monocyte supernatants which did not contain IFN-γ in significant amounts. All supernatants contained IFN-α. An antiserum against lFN-α partially reduced the cytostasis induced by monocyte supernatants. This cylostasis was totally abolished by r TNF antiserum, suggesting that IFN-α modulates the growth-inhibitory activity of TNF in the monocyte supernatants It appeared that the different effects of recombinant and natural TNF on fibroblast growth can probably not be attributed to monocyte-derived TNF-modulating factors alone. Thus, recombitiant and natural TNF may differ in a way that affects their capacity to induce cytostasis of normal fibroblasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3083.1987.tb02249.x
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  • 9
    Electronic Resource
    Electronic Resource
    XRF induced by PIXE: Comparison with radioisotope XRF (1987)
    Springer
    Applied physics 42 (1987), S. 327-329 
    Details
    ISSN: 1432-0630
    Keywords: 79.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract XRF induced by PIXE (XRF-PIXE) using silver as a primary target was compared with a standard radioisotope XRF system using Cd-109 as a primary exciting source, for the analysis of single-element thin standards. The sensitivity of the two methods were determined for elements from Cl to Mo. XRF is found to be more sensitive for elements from Cl to Mn, whereas XRF-PIXE is found to be more suitable for elements from Fe to Mo. Both techniques can be considered as complementary to each other.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00616571
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  • 10
    Electronic Resource
    Electronic Resource
    Comparison of the effects of chlordiazepoxide and CL 218,872 on serum corticosterone concentrations in rats (1987)
    Springer
    Psychopharmacology 91 (1987), S. 467-472 
    Details
    ISSN: 1432-2072
    Keywords: Benzodiazepines ; Triazolopyridazines ; Corticosterone ; Anxiety ; Stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Fifteen minute exposure to a novel environment plus 120 dB sound stimulation produced a three-fold increase in serum corticosterone concentrations in rats. A low dose of intraperitoneally (IP) administered chlordiazepoxide (CDP) (5 mg/kg) attenuated this response, whereas a higher dose (20 mg/kg) elevated corticosterone concentrations in rats not subjected to sound stress. Parallel results were obtained after intracerebroventricular (ICV) drug administration, with a low dose of CDP (5 μg) reducing the sound stress response and higher doses (25 and 50 μg) increasing corticosterone concentrations in unstressed animals. Thus, despite the presence of benzodiazepine (BDZ) receptors at every level of the hypothalamic-pituitary-adrenocortical axis, it appears that BDZs alter the activity of this system via an interaction with BDZ receptors in brain. CL 218,872 (2.5–20 mg/kg), a novel non-BDZ anxiolytic compound, did not attenuate the corticosterone elevation produced by sound stimulation, and also failed to alter baseline corticosterone concentrations in unstressed animals. The fact that CL 218,872 is a selective agonist for brain Type I BDZ receptors suggests that BDZs are not influencing corticosterone secretion through an interaction with this BDZ receptor subtype. Furthermore, these results indicate that stress (as measured by pituitary-adrenocortical activation) can be dissociated from anxiety (as measured by conflict paradigms), thus challenging the validity of the corticosteroid stress test as a screening procedure for anxiolytic activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216012
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