Interception of comet Hyakutake's ion tail at a distance of 500 million kilometres

Remote sensing observations and the direct sampling of material from a few comets have established the characteristic composition of cometary gas. This gas is ionized by solar ultraviolet radiation and the solar wind to form 'pick-up' ions, ions in a low ionization state that retain the same compositional signatures as the original gas. The pick-up ions are carried outward by the solar wind, and they could in principle be detected far from the coma (Sampling of pick-up ions has also been used to study interplanetary dust, Venus' tail and the interstellar medium.) Here we report the serendipitous detection of cometary pick-up ions, most probably associated with the tail of comet Hyakutake, at a distance of 3.4 AU from the nucleus. Previous observations have provided a wealth of physical and chemical information about a small sample of comets, but this detection suggests that remote sampling of comet compositions, and the discovery of otherwise invisible comets, may be possible.     

Neue mehrfache Untersuchungen am gleichen Kammerwasser menschlicher Augen

Summary The normal human aequous has a volume of 0.12–0.20 cm³ and its protein content is from 10 to 20 mg%. We ascertained the specific weight by the falling drop method in a mixture of xylol and brombenzene. In order to estimate the protein content, we placed a series of drops from the human aequous on filter paper with the Agla pipette; they were then tinted with amido-black and the optical density of the eluted spots was read in the Beckman spectrophotometer. The remnants of 2–3 specimens of human aequous were then brought together and concentrated there until the protein concentration is just sufficient to allow a separation into the various fractions by paper-electrophoresis.      

Tension transients in glycerol-extracted fibres of insect fibrillar muscle(Lethocerus maximus)

Zusammenfassung Mit Wasser-Glyzerin extrahierte fibrilläre Muskelfasern (Fasermodelle) vonLethocerus maximus zeigen im ATP-Bad nach plötzlicher Dehnung das Phänomen der Dehnungsaktivierung, gefolgt von einer gedämpften, temperaturabhängigen isometrischen Oszillation der Kontraktionsspannung. Die Frequenz entspricht offenbar der Eigenfrequenz zyklisch tätiger « KontraktionsbrÜcken » zwischen Aktin und Myosin.

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Supported by Grant No. RU 154/1 of the Deutsche Forschungsgemeinschaft.     

Superallowed Gamow-Teller decay of the doubly magic nucleus 100Sn

The shell structure of atomic nuclei is associated with 'magic numbers' and originates in the nearly independent motion of neutrons and protons in a mean potential generated by all nucleons. During β(+)-decay, a proton transforms into a neutron in a previously not fully occupied orbital, emitting a positron-neutrino pair with either parallel or antiparallel spins, in a Gamow-Teller or Fermi transition, respectively. The transition probability, or strength, of a Gamow-Teller transition depends sensitively on the underlying shell structure and is usually distributed among many states in the neighbouring nucleus. Here we report measurements of the half-life and decay energy for the decay of (100)Sn, the heaviest doubly magic nucleus with equal numbers of protons and neutrons. In the β-decay of (100)Sn, a large fraction of the strength is observable because of the large decay energy. We determine the largest Gamow-Teller strength so far measured in allowed nuclear β-decay, establishing the 'superallowed' nature of this Gamow-Teller transition. The large strength and the low-energy states in the daughter nucleus, (100)In, are well reproduced by modern, large-scale shell model calculations.