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  • 1
    ISSN: 1432-1106
    Keywords: Key words Long-latency reflexes ; Magnetic brain stimulation ; Sensory feedback
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Stimulation of cutaneous foot afferents has been shown to evoke a facilitation of the tibialis anterior (TA) EMG-activity at a latency of 70–95 ms in the early and middle swing phase of human walking. The present study investigated the underlying mechanism for this facilitation. In those subjects in whom it was possible to elicit a reflex during tonic dorsiflexion while seated (6 out of 17 tested), the facilitation in the TA EMG evoked by stimulation of the sural nerve (3 shocks, 3-ms interval, 2.0–2.5× perception threshold) was found to have the same latency in the swing phase of walking. The facilitation observed during tonic dorsiflexion has been suggested to be – at least partly – mediated by a transcortical pathway. To investigate whether a similar mechanism contributes to the facilitation observed during walking, magnetic stimulation of the motor cortex (1.2× motor threshold) was applied in the early swing phase at different intervals in relation to the cutaneous stimulation in 17 subjects. In 13 of the subjects, the motor potentials evoked by the magnetic stimulation (MEPs) were more facilitated by prior sural-nerve stimulation (conditioning-test intervals of 50–80 ms) than the algebraic sum of the control MEP and the cutaneous facilitation in the EMG when evoked separately. In four of these subjects, a tibialis anterior H-reflex could also be evoked during walking. In none of the subjects was an increase of the H-reflex similar to that for the MEP observed. In five experiments on four subjects, MEPs evoked by magnetic and electrical cortical stimulation were compared. In four of these experiments, only the magnetically induced MEPs were facilitated by prior stimulation of the sural nerve. We suggest that a transcortical pathway may also contribute to late cutaneous reflexes during walking.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 52 (1996), S. 237-247 
    ISSN: 0006-3592
    Keywords: bioreactor monitoring ; semi-on-line analysis ; aseptic sampling ; FIA ; SIA ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Monitoring of substrates and products during fermentation processes can be achieved either by on-line, in situ sensors or by semi-on-line analysis consisting of an automatic sampling step followed by an ex situ analysis of the retrieved sample. The potential risk of introducing time delays and signal bias during sampling makes it necessary to distinguish between real-time, on-line, in situ methods and semi-on-line analysis. In addition, semi-on-line analyzers are often mechanically complex - a circumstance which has to be given special attention during their industrial use on a routine basis. This review on semi-on-line analysis will focus both on the dynamics and precision of aseptic sampling devices and on the performance of flow injection analysis (FIA) and sequential injection analysis (SIA), especially with regard to their robustness when used in industry. © 1996 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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