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  • 1995-1999  (3)
  • 1998  (3)
  • hole concentration  (2)
  • Electrogastrography  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of superconductivity 11 (1998), S. 455-461 
    ISSN: 1572-9605
    Keywords: Electrical resistivity ; Hall effect ; hole concentration ; normal-state properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We report detailed studies of the superconducting and normal-state transport properties in NdBa2Cu3O7−y , Nd0.9Ca0.1Ba2Cu3O7−y , and Nd0.8Pr0.2Ba2Cu3O7−y , systems. We found a linear temperature dependence of resistivity ρ and the Hall number n H above T c. For a given sample ρ∝n H, which is inconsistent with any simple transport model in science (ρ∝1/n). However, ρ and n H at a fixed temperature for these three samples follow a relation ρ∝1/n H. This is evidence that n H could scale with actual mobile carrier concentration. The unit cell volume V is a linear function of n H. The T c −V−n H diagram indicates that there exist an optimal concentration n H and an optimal V for T c in these systems.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of superconductivity 11 (1998), S. 563-567 
    ISSN: 1572-9605
    Keywords: Y(Ba2 − y Sr y )Cu3O6 + δ ; high-T c superconductor ; X-ray-absorption near-edge-structure spectra ; hole concentration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The chemical control of underdoped and overdoped states in the Y(Ba2 − y Sr y )Cu3O6 + δ (δ∼0.1 and 0.9) compounds has been observed by high-resolution O K-edge X-ray-absorption near-edge-structure spectra. The chemical substitution of Sr for Ba in the fully-oxygenated Y(Ba2−y Sr y )Cu3O6 + δ (δ∼0.9) compounds gives rise to high hole concentrations within both the CuO2 planes and the out-of-plane sites, leading to the overdoped state and the decrease in the superconducting transition temperature from 92 K for y=0 to 84 K for y=0.8. In contrast, an increase in the Sr content in the oxygen-deficient Y(Ba2 − y Sr y )Cu3O6 + δ (δ∼0.1) compounds did not indicate superconductivity. The oxygen-deficient compounds exhibit the underdoped state due to the low hole concentration.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Annals of biomedical engineering 26 (1998), S. 859-869 
    ISSN: 1573-9686
    Keywords: Spectral analysis ; Matching pursuit ; Stomach ; Gastric motility ; Electrogastrography ; Evolutionary programming ; Signal analysis ; Electrogastrogram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The electrogastrogram (EGG) is a surface measurement of gastric myoelectrical activity. The normal frequency of gastric myoelectrical activity in humans is 3 cycles/min. Abnormal frequencies in gastric myoelectrical activity have been found to be associated with functional disorders of the stomach. The aim of this article was, therefore, to develop new time-frequency analysis methods for the detection of gastric dysrhythmia from the EGG. A concept of overcomplete signal representation was used. Two algorithms were proposed for the optimization of the overcomplete signal representation. One was a fast algorithm of matching pursuit and the other was based on an evolutionary program. Computer simulations were performed to compare the performance of the proposed methods in comparison with existing time-frequency analysis methods. It was found that the proposed algorithms provide higher frequency resolution than the short time Fourier transform and Wigner-Ville distribution methods. The practical application of the developed methods to the EGG is also presented. It was concluded that these methods are well suited for the time-frequency analysis of the EGG and may also be applicable to the time-frequency analysis of other biomedical signals. © 1998 Biomedical Engineering Society. PAC98: 8780+s, 0705Kf
    Type of Medium: Electronic Resource
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