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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 900-903 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Data obtained from a set of asymmetric GaAs/AlGaAs double-barrier resonant tunneling structures is presented. Low-temperature I(V) characteristics, temperature dependencies, and magnetotunneling have been investigated. The data confirm conclusions drawn in previous studies on symmetric structures, lending further support to the description of tunneling in terms of sequential processes and momentum randomization most likely induced by interface roughness scattering in the well.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1918-1922 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new beetle-like scanning tunneling microscope is presented that operates under ultrahigh vacuum conditions and at temperatures down to 7 K. Magnetic fields up to 8 Tesla can be applied using a movable superconducting magnet. The entire setup is described in detail and test measurements are presented.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A systematic μSR study of the local magnetic field distribution in a series of oxygen deficient YBa2Cu3O x samples with 6.5⩽x⩽7.0 is reported. Special attention was given to perform the experiments under the same conditions, so that the oxygen content of the measured samples was the only parameter varied. The behavior of the depolarization rate σ as a function of the oxygen contentx was found to have strong similarities with the behavior of the critical temperatureT c as a function ofx. In particular, two step-like increases of σ were observed abovex=6.7 and 6.9. The temperature dependence of the normalized depolarization rate σ(T)/σ(0) is well described by the two-fluid model forx⩾6.781(1) and clearly deviates from this behavior forx⩽6.704(1). Our results are compared to those obtained by other groups.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 15 (1994), S. 67-75 
    ISSN: 0197-8462
    Keywords: EEG ; electroencephalography ; LEET ; electromagnetic fields ; sleep ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The sleep inducing effect of a 15 min treatment with either an active or an inactive Low Energy Emission Therapy (LEET) device emitting amplitude-modulated electromagnetic (EM) fields was investigated in a double-blind cross-over study performed on 52 healthy subjects. All subjects were exposed to both active and inactive LEET treatment sessions, with an interval of at least I week between the two sessions. LEET consists of 27.12 MHz amplitude-modulated (sine wave) EM fields emitted intrabuccally by means of an electrically conducting mouthpiece in direct contact with the oral mucosa. The estimated local peak SAR is less than 10 W/kg in the oral mucosa and 0.1 to 100 mW/kg in brain tissue. No appreciable sensation is experienced during treatment, and subjects are therefore unable to tell whether they are receiving an active or an inactive treatment. In this study the active treatment consisted of EM fields intermittently amplitude-modulated (sine wave) at 42.7 Hz for 3 s followed by a pause of 1 s during which no EM fields were emitted. During the inactive treatment no EM fields were emitted. Baseline EEGs were obtained and 15 min post-treatment EEGs were recorded and analyzed according to the Loomis classification.A significant decrease (paired t test) in sleep latency to stage B2 (-1.78 ± 5.57 min, P = 0.013), and an increase in the total duration of stage B2 (1.15 ± 2.47 min, P = 0.0008) were observed on active treatment as compared with inactive treatment. The deepest sleep stage achieved (B1 to D) following active treatment was also significantly higher than that following inactive treatment (P = 0.040). We conclude 27.12 MHz electromagnetic fields, intermittenly amplitude-modulated at 42.7 Hz, result in a significant sleep inducing effect in healthy subjects. © 1994 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0044-2313
    Keywords: High temperature superconductors ; copper oxygen chains ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Effekt des Carbonateinbaus auf die strukturellen und supraleitenden Eigenschaften der Doppelkettenverbindung Y2Ba4Cu7O15-xStrukturelle Untersuchungen von Pulverpräparaten von Y2Ba4Cu7O15-x mit unterschiedlichem Carbonatgehalt wurden durchgeführt. Die Rietveld-Verfeinerung mit Röntgen-Pulver-Daten zeigt einen bemerkenswerten Einfluß des Carbonateinbaus auf die Gitterkonstanten. Ein auffälliger Effekt ist die Herabsetzung von Tc mit steigendem Carbonatgehalt. Wir führen diese Effekte auf einen Einbau des Carbonations in das Gitter, Fehlstellen an der Cu(1) Position und eine mögliche Fehlorientierung der einfachen Kupfer-Sauerstoffketten zurück. Eine Änderung der Struktur (z. B. Überstruktur) konnte nicht gefunden werden.
    Notes: Structural investigations on powder samples of Y2Ba4Cu7O15-x with different carbonate content have been performed. Powder x-ray Rietveld refinements showed the remarkable influence of carbonate incorporation on the lattice parameters. Most important is the decrease of Tc with increasing carbonate content. We assign these effects to an incorporation of the carbonate ion into the crystal lattice, copper vacancies at the Cu(1) position and a possible misorientation of the copper oxygen single chains. No change of the structure (e. g. superstructure) could be found.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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