24,308 research outputs found
The cupric complexes of glycine and of alanine
The following report is the first of a projected series of studies of the physical chemistry of the compounds of the heavy metals, particularly of copper and of iron, with substances of biological importance. These studies are invited by the accumulation in recent years of examples of the importance of the heavy metals in biological chemistry
Ceric and ferrous dosimeters show precision for 50-5000 rad range
Ammonium thiocyanate, added to the usual ferrous sulfate dosimeter solution, yielded a very stable, precise and temperature-independent system eight times as sensitive as the classical Fricke system in the 50 to 5000 rad range. The ceric dosimeters, promising for use in mixed radiation fields, respond nearly independently of LET
Why do some spotted stars become bluer as they become fainter?
Chromospherically active, spotted stars generally become redder as well as
fainter when large starspots rotate into view on the stellar disc. However, the
RS CVn system UX Ari (a triple-lined system), becomes bluer as it gets fainter.
One possible explanation is that hot, bright facular regions accompany the
cool, dark photospheric spots of the active component. The bluer flux of the
hotter, inactive component does not appear to be sufficient to explain the
observed behaviour. We have begun a search for additional chromospherically
active stars with a similar relation between colour and brightness, to
investigate whether these relations can be explained in the same way. Our
results for V711 Tau are presented here, and we conclude that the faculae
explanation holds also in this case.Comment: 3 pages, 1 figure, proceedings from the 13th Cambridge Workshop on
cool stars, stellar systems, and the Sun, Hamburg, Germany, July 2004,
ESA-SP, in pres
Systems and methods for determining radio frequency interference
The presence, frequency and amplitude of radio frequency interference superimposed on communication links originating from a terrestrial region and including a relay in a geostationary spacecraft are determined by pointing a narrow beam antenna on the satellite at the terrestrial region. The level of noise radiated from the region to the antenna is measured at a terrestrial station that is usually remote from the region. Calibrating radio signals having a plurality of predetermined EIRP's (Effective Isotropic Radiated Power) and frequencies in the spectrum are transmitted from the region through the spacecraft narrow beam antenna back to the station. At the station, the levels of the received calibrating signals are separately measured for each of the frequency bands and EIRP's
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