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21.
Alexandru Dimca Fayçal Maaref Claude Sabbah Morihiko Saito 《Mathematische Annalen》2000,318(1):107-125
Using local cohomology and algebraic -Modules, we generalize a comparison theorem between relative de Rham cohomology and Dwork cohomology due to N. Katz, P. Monsky,
A. Adolphson and S. Sperber.
Received June 10, 1999 / Published online July 20, 2000 相似文献
22.
Lantz MA Hug HJ van Schendel PJ Hoffmann R Martin S Baratoff A Abdurixit A Guntherodt H Gerber C 《Physical review letters》2000,84(12):2642-2645
A low temperature scanning force microscope (SFM) operating in a dynamic mode in ultrahigh vacuum was used to study the Si(111)- (7x7) surface at 7.2 K. Not only the twelve adatoms but also the six rest atoms of the unit cell are clearly resolved for the first time with SFM. In addition, the first measurements of the short range chemical bonding forces above specific atomic sites are presented. The data are in good agreement with first principles computations and indicate that the nearest atoms in the tip and sample relax significantly when the tip is within a few A of the surface. 相似文献
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Hot-film anemometry for measuring lateral line stimuli 总被引:2,自引:0,他引:2
A hot-film anemometer system has been calibrated and evaluated for the measurement of sinusoidal water motions used in stimulating the mechanosensory lateral line system of a teleost fish. The response of the anemometer system to water motions created by a vibrating sphere was measured over a wide range of frequencies, intensities, and distances from the sphere. The amplitude response of the system to signals along the axis of sphere vibration was found to be linear over a 50-dB range for frequencies from 10-200 Hz, with the lowest end of the dynamic range (between 10(-8) and 10(-9) m) corresponding to physiological measures of best sensitivity in the lateral line system of the mottled sculpin, Cottus bairdi. The measured attenuation of the signal with distance was also linear over this frequency range out to distances of six times the radius ( = 3 mm) of the sphere and followed the predicted falloff rate for a dipolar source. The linear response of the anemometer system over a wide dynamic range encompassing the detection range of the lateral line system, and the match between predicted and measured motions at varying distances from a dipolar source, indicates that hot-film anemometry is a useful technique for measuring low-level, low-frequency signals likely to stimulate the lateral line system and other hydrodynamic detectors. 相似文献
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Fay RR 《The Journal of the Acoustical Society of America》2011,129(5):3367-3372
The masking effects of white and amplitude comodulated noise were studied with respect to simple signal detection and sound source determination in goldfish. A stimulus generalization method was used to determine the signal-to-noise ratio required to completely determine the signal's characteristics. It was found that the S∕N required for this determination is about 4 dB greater than that required for signal detection, or was about 4 dB greater than the critical masking ratio. This means that the potential harm to fish of a given masking noise is at least 4 dB greater than previously thought, based on critical masking ratios. However, for amplitude comodulated noise between 10 and 50 Hz modulation rate, the potential harmful effects are up to 5.3 dB less than would be predicted from the critical masking ratio for unmodulated noise. 相似文献
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Fayçel Jemmezi Samar Chtiba Jameleddine Khiari 《Journal of heterocyclic chemistry》2013,50(2):206-208
The symmetrical vinamidinium salts were allowed to react with malononitrile in refluxing ethanol in the presence of ammonium acetate for 12 h to afford the 2‐amino‐5‐aryl or formylpyridine‐3‐carbonitriles. 相似文献
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