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  • 1
    Electronic Resource
    Electronic Resource
    Detection of deep levels and compensation mechanism in undoped, liquid-encapsulated Czochralski n-type GaAs (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 2245-2250 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Undoped n-GaAs with a 300 K resistivity between 10−1 and 108 Ω cm (electron concentration between 1×107 and 5×1015 cm−3 ) grown in quartz crucibles by the liquid-encapsulated Czochralski (LEC) technique was investigated by thermally stimulated current (TSC), temperature-dependent Hall effect (TDH), and deep-level transient spectroscopy (DLTS). Using Schottky contacts the TSC method could be extended to medium-resistivity samples. The strongly varying electron concentrations are correlated to varying TDH activation energies. The correlation between the donors dominating the electrical equilibrium properties and the electron traps detected by TSC and DLTS is discussed. Medium-deep and deep levels are present in this LEC material in such high concentrations that they must be taken into account in the compensation mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348703
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    High-frequency and low-frequency heart-rate fluctuation analysis in newborns—A review of possibilities and limitations (1992)
    Springer
    Basic research in cardiology 87 (1992), S. 193-204 
    Details
    ISSN: 1435-1803
    Keywords: Heart-rate fluctuations ; neonates ; respiratorymovements ; respiratory sinusarrhythmia ; nonrespiratoryrhythms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Respiratory sinus arrhythmia (RSA) has been traditionally defined as the high-frequency component of heart-rate fluctuations (HRF) synchronous with the respiratory movements (RM), i.e., the frequency of RSA corresponds to the respiration rate. It can be shown that at defined relations of mean heart and respiration rate some essential effects must be taken into consideration in studies using RSA parameters The relevance of these effects is shown and a new strategy of RSA quantification demanded, at least in neonates. The diagnostic importance, physiological background and future application of the low-frequency components of the neonatal HRF are reviewed on the basis of our own results. Nonrespiratory cardiovascular HRF cannot always be detected in the neonate by power spectral analysis. Movement-related HRF have a potential diagnostic importance per se, but may also artefactually disturb the quantification of other HRF components. Long-term trends can be used to describe sleep-state related trends and their disturbances.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00801966
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Zooplankton distribution in the coastal upwelling system along the Banc d'Arguin, Mauritania (1993)
    Springer
    Hydrobiologia 258 (1993), S. 133-149 
    Details
    ISSN: 1573-5117
    Keywords: zooplankton ; copepods ; upwelling ; Mauritania
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the framework of the Dutch Mauritania Expedition 1988, zooplankton was sampled in the beginning of the spring upwelling season at 44 stations along the Banc d'Arguin, Mauritania. Distribution patterns of oceanic and neritic copepod species and especially of the upwelling indicator Calanoides carinatus (Kröyer) were analysed in search for direct proof of circulation of ocean upwelling water over the inshore banks. The vertical temperature distribution at the stations pointed to upwelling in two different parts of the shelf area. According to the copepod data the two upwellings were of a different nature. A restricted area at the shelf edge near Cap Timiris appeared to represent a relatively stable coastal upwelling situation. Upwelled water present near Cap Blanc was found to have traveled quite recently over a considerable part of the shelf. In the central area between the two upwellings, ‘Banc-water’ extended from the shelf into the ocean. The possible impact of the observed circulation of ocean water on productivity of the shelf benthic system is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00006192
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Using discrete Hibert transformation for interval-related calculation of the respiration rate in neonates (1991)
    Springer
    Medical & biological engineering & computing 29 (1991), S. 249-253 
    Details
    ISSN: 1741-0444
    Keywords: Discrete Hilbert transformation ; Neonates ; Respiration rates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract From the basis of the fast Fourier transformation (FFT), the discrete Hilbert transformation (DHT) is used to compute the instantaneous respiration rate in neonates. This interval-related computation of respiration rate must be combined with a concept of adaptive filtration of the respiratory movements. This strategy is performed by adaptive recursive estimations of mean values with different adaptation constants. Additionally, a frequency band limitation is carried out on the basis of the peak characteristic of the power spectrum (respiratory movements). By means of the adaptive estimation of the variance of respiratory movements, an amplitude-time window is calculated to choose between epochs with breaths and apnoea.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02446706
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  • 5
    Electronic Resource
    Electronic Resource
    Use of discrete Hilbert transformation for automatic spike mapping: A methodological investigation (1991)
    Springer
    Medical & biological engineering & computing 29 (1991), S. 242-248 
    Details
    ISSN: 1741-0444
    Keywords: Discrete Hilbert transform ; EEG ; Fast Fourier transform ; Spike mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract On the basis of discrete Hilbert transform (DHT) realised by fast Fourier transform (FFT), a new strategy for automatic spike mapping is introduced. The further computation of the EEG time series after DHT results in the time series of the momentary power and the momentary frequency. Both are used for the solution of the main requirements of automatic spike mapping. The spike-mapping concept introduced meets the requirements of efficient automatic spike detection and also has an insensitivity with regard to EMG interference and transient signal components, a frequent cause of false positive detections. Additionally, there are advantages if the momentary power of the spike is mapped instead of the spike potential. the use of momentary power makes a combination of power spectral mapping and spikemapping strategies possible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02446705
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    Paper (German National Licenses)
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