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911.
912.
Research indicates that ventilating systems can be designed for higher ventilation efficiency in the zone of occupation than systems designed for complete mixing. Expressions for ventilation efficiency are derived using a two-box theoretic model. These definitions of ventilation efficiency can be used for practical measurements, and also seem to be valid for multibox schemes. Measurements reviewed show that diagonal schemes are the most efficient. Short-circuiting schemes, with warm air supply along the ceiling and high wall exhaust, produce very low efficiencies. The mathematical model predicts high efficiencies using diffuse air supply directly to the zone of occupation, if the air is not used heating. 相似文献
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915.
H. Kangro F. L. Boschke G. Feichtinger H. Primas W. Kundt H. Reeh G. Lehner G. v. Minnigerode S. Steeb G. Habermehl R. Hoppe H. Kessler L. Horner M. Kuhnert-Brandstätter L. Jaenicke D. Neubert K. Mothes H. Rembold R. Dietz P. Karlson V. Ziswiler E. P. Martin A. Ruthmann V. Neuhoff R. D. Bauer H. Sioli 《Die Naturwissenschaften》1972,59(3):127-132
916.
本文通过在东非进行的一系列野外和实验室试验,研究了丰富的红树林十足类螃蟹迈纳新胀蟹(Neosarmatium meinerti)对落叶的清理.在地势高的海榄雌(Avicennia meinerti)潮间带,螃蟹掩埋了所有红树林林区海底的落叶,而且会在2小时内平均消耗其中的67%. 相似文献
917.
In birds, the position and extent of the region of binocular vision appears to be determined by feeding ecology. Of prime
importance is the degree to which vision is used for the precise control of bill position when pecking or lunging at prey.
In birds that do not require such precision (probe and filter-feeders), the bill falls outside the binocular field, which
extends above and behind the head, thus providing comprehensive visual coverage. Flamingos Phoenicopteridae are highly specialised
filter-feeders. They employ a unique technique that does not require accurate bill positioning in which the inverted head
is placed between the feet. Feeding flamingos often walk forwards with the head pointing “backwards”. Here we show that in
Lesser Flamingos Phoeniconaias minor visual fields are in fact the same as those of birds that feed by precision pecking and that feeding flamingos are blind
in the direction of their walking. We suggest that this is due to the requirement for accurate bill placement when flamingos
feed their chicks with “crop-milk”, and possibly when building their nest. We propose that chick-feeding may be the ultimate
determinant of visual field topography in birds, not feeding ecology. 相似文献
918.
Martin Heisenberg 《Die Naturwissenschaften》1983,70(2):70-78
Initiation as a basic property of behavioral activity is functionally analyzed and discussed at the level of voluntary behavior. Fixed action patterns often are not released by stimuli but are generated by the animal itself through brain processes of the Darwinian type. Analogous to mutations, behavioral “subroutines” are brought up by chance and are subjected to selection either by the change in the situation (trial and the elimination of error) or by mental activity suppressing inappropriate behavior even before it is executed.Initiation improves the chance of survival. It is a prerequisite of goal-oriented behavior, an essential constituent of operant conditioning and presumably the first step in the evolution of thought. According to I. Kant a person is free if, by following his own directive, he does what has to be done. This definition meets the two central criteria of initiation: the independence of releasing stimuli and the adaptive value of the behavior generated. 相似文献
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920.