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  • 1975-1979  (4)
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  • 1
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary It is shown that Km of ChE is not affected by the neurohormones but Vmax is increased and decreased in presence of acceleratory and inhibitory neurohormones respectively. Hence it is suggested that the neurohormones might modulate the enzyme activity by altering the maximal velocities (Vmax) rather than affecting the enzyme affinity (Km) towards the substrate.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Beim südindischen SkorpionHeterometrus fulvipes zeigt der Gehalt an Acetylcholin folgende Verteilung: Nervenkomplex des Cephalothorax 〉 ventraler Nervenstrang 〉 Blut; er unterliegt tageszeitlichen Schwankungen im Nervenkomplex des Cephalothorax und im Blut. Aus der zeitlichen Verschiebung der Maxima wird abgeleitet, dass der Nervenkomplex des Cephalothorax Acetylcholin produziert und dieses an das Blut abgibt.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Acetylcholinesterase (AChE) activity in the central nervous system and foot muscle in the garden snail,Cryptozona ligulata, was maximum at 20.00 h and minimum at 08.00 h during the 24 h period of the day. The cyclic variation in acetylcholine (ACh) was out of phase with that of AChE. In the body fluid, ACh content showed a rhythm with maximum at 00.00 h and minimum at 12.00 h, with AChE activity being in phase with it. The rhythm of spontaneous electrical activity of the nervous system was in phase with that of AChE activity in tissues. Perfusion with body fluid collected from snails at 20.00 h elevated the spontaneous electrical activity, while body fluid collected at 08.00 h inhibited the activity. Perfusion with extract prepared from the central nervous tissue isolated at 08.00 h elevated the electrical activity, while the extract prepared from nervous tissue isolated at 20.00 h inhibited the activity. Perfusion with 10−4 M acetylcholine chloride solution elevated the electrical activity. It is suggested that the synthesis and release of ACh occur in a regular diel cycle in tissues. These changes, among others, may be responsible for the observed diurnal rhythmicity in electrical activity in the snail.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-0794
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The current error of 0.0025 on the lunar homogeneity parameterI/MR 2 is dominated by the uncertainties in theC 20 andC 22 gravity harmonics. This error level is equivalent to a 4.20 gm cm−3 density uncertainty for a lunar interior model having a core 300 km in radius. Covariance analyses are performed using Doppler data from the relay satellite of the proposed Lunar Polar Orbiter mission to determine an optimum reduction strategy which obtains an order of magnitude improvement in the gravity estimates. Error studies show the long-arc reduction method obtains results which are an order of magnitude more accurate than the short-arc technique. The nominal 4000 km circular orbit of the relay satellite is very sensitive to the unmodeled effects of gravity harmonics of degree 5 through 9. Results from this orbital geometry indicate that it may not be possible to achieve the desired order of magnitude accuracy improvement. A modified orbit having the identical orbital conditions as the nominal one, but with a larger semi-major axis of 7000 km is studied. Results show the desired order of magnitude improvement can be achieved when a complete fourth degree and order model and some fifth and sixth degree terms are estimated while considering the unmodeled effects of the remaining harmonics through degree and order eight. Studies also show a 50% additional improvement inC 22 can be achieved if differential differenced Doppler is also processed with the direct Doppler. The improved uncertainty inI/MR 2 reduces the core density error from 4.20 gm cm−3 to 0.1 gm cm−3 for the case of a lunar density model having a 300 km core radius.
    Type of Medium: Electronic Resource
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