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  • 1990-1994  (14)
  • 1925-1929
  • 1870-1879
  • 1992  (14)
  • 1
    Electronic Resource
    Electronic Resource
    Electronic properties of silicon δ-doped InSb (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 671-675 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated magneto-transport and cyclotron resonance (CR) of two-dimensional electron gas in silicon δ-doped p-InSb under a magnetic field of up to 12 T at 4.2 K. Because there are multiple subbands occupied, Shubnikov–de Haas oscillations show a beating behavior. The CR spectra also display several peaks originating from different subbands. Effective masses of electrons associated with the lowest three subbands can therefore be directly determined, and they are in excellent agreement with a self-consistent calculation, which takes into account the electrostatic Poisson equation, the Schrödinger equation, and realistic sample parameters. Furthermore, we observed an absorption peak, whose resonance position has anomalous angle dependence. It is attributed to impurity CR where donors are in the vicinity of the δ-doped sheet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351850
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  • 2
    Electronic Resource
    Electronic Resource
    Design considerations for z-pinch driven photoresonant x-ray lasing in neonlike krypton (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 4671-4677 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A neonlike x-ray laser photoresonant pumping scheme is explored. An attractive design is a coaxial z-pinch consisting of an inner krypton lasant plasma surrounded by a carbon shell that itself is surrounded by a stagnated krypton plasma. The photoresonant radiation emitted from the outer plasma passes inwardly through the carbon shell and photoexcites lasant electrons to the 3s, 3d, and 4d levels. It is calculated that monochromatic pump powers of 30 GW/cm eV can be achieved for the 4d neonlike resonance line while powers of 100–200 GW/cm eV are attainable for the 3s and 3d resonance lines. The gain in several neonlike 3s-3p transitions is calculated as a function of temperature and density of the lasant plasma. Reasonable gain in only the 3p-3s (J=0–1) transition is obtained for high-density, high-temperature lasant conditions. This gain, which is driven by monopole excitation from the ground state to the 3p (J=0) level, is nearly independent of the presence of pump radiation. For low-density, low-temperature lasants, optimal gain is obtained in the 3p-3s (J=2–1) transitions. Under these conditions, the pump radiation is necessary to photoionize and photoexcite the lasant plasma to the neonlike stage while radiative decay from the resonantly pumped 4d level to the 3p (J=2) states provides the major upper lasing level pump mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350657
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  • 3
    Electronic Resource
    Electronic Resource
    Large temperature changes induced by molecular beam epitaxial growth on radiatively heated substrates (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 2338-2340 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have performed optical transmission measurements on radiatively heated GaAs substrates as a function of molecular beam epitaxial growth of InAs, GaSb, AlSb, and GaAs films. The energy gap of the GaAs substrate is observed to decrease strongly in energy when materials with band gaps smaller than GaAs are deposited. This decrease in energy gap is a consequence of a substantial increase in growth temperature induced by the deposition of the film. We have observed increases in temperature of over 150 °C from the temperature measured before film growth. Because the thermocouple is weakly coupled to the radiatively heated substrate, conventional temperature controllers are ineffective at measuring or accounting for this change in temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108236
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  • 4
    Electronic Resource
    Electronic Resource
    Eosinophilic granuloma of lymph nodes associated with metastatic papillary carcinoma of the thyroid (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Histopathology 20 (1992), S. 0 
    Details
    ISSN: 1365-2559
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2559.1992.tb00952.x
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  • 5
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    Unknown
    Conal Condren, "George Lawson's 'Politica' and the English Revolution" (Book Review) (1992)
    Gloucester : Periodicals Archive Online (PAO)
    Parliamentary history. 11:2 (1992) 305 
    Details
    ISSN: 0264-2824
    Topics: History , Political Science
    Notes: Reviews
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:h227-1992-011-02-000012
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  • 6
    Electronic Resource
    Electronic Resource
    Intraspecific variation ofDrosophila buzzatii larval breeding success onOpuntia: A yeast-plant-insect relationship (1992)
    Springer
    Entomologia experimentalis et applicata 64 (1992), S. 87-95 
    Details
    ISSN: 1570-7458
    Keywords: Isofemale lines ; yeasts ; Opuntia ; plant-insect relationship ; genetic variability ; viability ; developmental time ; Drosophila buzzatii
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cactophilic species,Drosophila buzzatii, normally breeds in decaying pockets ofOpuntia cladodes, in which there is a complex interaction with the microbial flora, especially yeast species. Isofemale lines were used to estimate genetic variation among larvae reared on their natural feeding substrate. Four naturally occurring cactophilic yeast species isolated from the same Tunisian oasis as theDrosophila population were used. Two fitness components were studied for each line, viability and developmental time. Genetic variations amongD. buzzatii lines were observed for both traits. A significant yeast species x isofemale line interaction for viability was also evidenced, suggesting the occurrence of specialized genotypes for the utilization of breeding substrates. This genetic heterogeneity in the natural population may favor a better adaptation to the patchily distribution of yeasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688997
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  • 7
    Electronic Resource
    Electronic Resource
    Structural studies of two tetracyclines: 4-dedimethylaminotetracycline hydrate and 6-methylene-5-oxytetracycline hydrochloride (1992)
    Springer
    Journal of chemical crystallography 22 (1992), S. 493-501 
    Details
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structures of two tetracycline derivatives, 4-dedimethylaminotetracycline hydrate and 6-methylene-5-oxytetracycline hydrochloride (methacycline·HCl), were determined using X-ray intensity data measured on a diffractometer. The first compound crystallizes with two chemical formula and one water molecule per asymmetric unit. The monoclinic crystal [a=7.174(5),b=12.029(9),c=21.117(15) Å,β=93.16(6)°] shows the space groupP21. Crystals of methacycline hydrochloride are orthorhombic, space groupP212121,a=9.472(1),b=11.921(3),c=18.945(4)Å, with one molecule in the asymmetric unit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01195412
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  • 8
    Electronic Resource
    Electronic Resource
    Slow wave sleep and 5-HT2 receptor sensitivity in generalised anxiety disorder: a pilot study with ritanserin (1992)
    Springer
    Psychopharmacology 108 (1992), S. 387-389 
    Details
    ISSN: 1432-2072
    Keywords: Anxiety ; Slow wave sleep ; Ritanserin ; 5-HT2 receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Eight patients with generalised anxiety disorder (GAD) and eight matched healthy controls had their polysomnogram measured on two occasions separated by 1 week. On one occasion they received the 5-HT2 receptor antagonist, ritanserin (5 mg orally) and on the other matching placebo. The increase in slow wave sleep produced by ritanserin was the same in GAD patients as in healthy controls. These findings do not support the hypothesis that GAD is associated with a generalised hypersensitivity of brain 5-HT2 receptors; however, the present data cannot exclude the presence of a regionally specific change in this receptor subtype in anxiety disorders.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245128
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of carbohydrate feedings on plasma free tryptophan and branched-chain amino acids during prolonged cycling (1992)
    Springer
    European journal of applied physiology 65 (1992), S. 513-519 
    Details
    ISSN: 1439-6327
    Keywords: Amino acids ; Carbohydrate feedings ; Free fatty acids ; Fatigue ; Serotonin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Brain serotonin (5-hydroxytryptamine, 5-HT) has been suggested to be involved in central fatigue during prolonged exercise. Changes in the ratio of plasma free tryptophan (free Trp) to branched-chain amino acids (BCAA) are associated with altered brain 5-HT synthesis. The purposes of this study were to describe systematically the effects of prolonged exercise on changes in plasma free Trp and BCAA and to examine the effects of carbohydrate (CHO) feedings on these same variables. Eight well-trained men [ $$\dot V{\text{O}}_{\text{2}} $$ max = 57.8 (SE 4.1) ml kg−1 min−1] cycled for up to 255 min at a power output corresponding toVO2 at lactate threshold (approximately 68%VO2max) on three occasions separated by at least 1 week. Subjects drank 5 ml kg−1 body wt−1 of either a water placebo, or a liquid beverage containing a moderate (6% CHO) or high (12% CHO) concentration of carbohydrate beginning at min 14 of exercise and every 30 min thereafter. Exercise time to fatigue was shorter in subjects receiving placebo [190 (SE 4) min] as compared to 6% CHO [235 (SE 10) min] and 12% CHO [234 (SE 9) min] (P〈0.05). Glucose and insulin decreased in the placebo group, and free Trp, free-Trp/BCAA, and free fatty acids increased approximately five- to sevenfold (P 〈 0.05). These changes were attenuated in a dose-related manner by the carbohydrate drinks. Plasma free Trp and plasma free fatty acids were highly correlated (r=0.86,P〈0.001). Plasma BCAA did not change in the placebo group, but decreased slightly in those receiving 6% CHO and 12% CHO (P〈0.05). No differences in heart rate, $$\dot V{\text{O}}_{\text{2}} $$ , plasma volume and respiratory exchange ratio were found. The results indicate that free Trp and free Trp/BCAA increase progressively during prolonged cycling to fatigue. This response was attenuated by CHO feedings. Changes in plasma free fatty acids probably play a prominent role in these responses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00602357
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  • 10
    Electronic Resource
    Electronic Resource
    Stable circulation in superfluid3He-A (1992)
    Springer
    Journal of low temperature physics 89 (1992), S. 47-56 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present evidence of stable nonzero circulation in superfluid3He-A around a 16 µm diameter wire. The measurements are made on a rotating cryostat at T≈0.15Tc. Circulation offects the splitting of the wire's normal modes, which changes the beat frequency in the emf across the wire as it vibrates in a magnetic field. The different beat frequencies at 14 and at 21 bar suggest that circulation is present at 21 bar. Furthermore, at 21 bar the beat frequency is a linear function of rotation velocity, as is expected if circulation is trapped around the wire. At 14 bar no effect of rotation is observed. We propose that at 21 bar the ground state texture has nonzero circulation of order h/2m3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00692577
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