When will a pulsar in supernova 1987a be seen?

The means by which a pulsar might be detected in the remnant of supernova 1987a in the Large Magelanic Cloud is examined. One possibility is that the slower-than-radioactive decay typically seen in the type II light curves is itself the sign of powering by the underlying pulsar, with the decline representing not the spinning down of the pulsar but rather the declining nebular opacity that would allow increasing amounts of the energy to escape as gamma rays. The test of this hypothesis (if the supernova conforms to type II expectations) would be to look for the "missing" energy in the form of those gamma rays that escape from the remnant instead of powering it.

Acetylcholinesterase in abnormal human muscle.

Fifty human muscle biopsies were examined for histochemical localization of acetylcholinesterase (AChE) activity. Six normal muscle samples had AChE at the myoneural junctions and around the periphery of many fibers. The AChE within the sarcoplasm itself was found in only a few atrophied fibers. However, 21 of 44 biopsies of abnormal muscles had sarcoplasmic AChE in more than 10% of their fibers. Such cases included Duchenne, limb-girdle and facio-scapulo-humeral dystrophy, neurogenic and spinal muscle atrophy, spinal cord injury, peripheral nerve injury, Schwartz-Jampel syndrome and myasthenic syndrome. Sarcoplasmic AChE is found in embryo muscle and usually declines after birth. It appears after denervation in the chicken but not the rat and remains in muscles of chickens with an inherited muscular dystrophy. The results of the human muscle study support the idea that in the human, as in the chicken, interruption of a neurally-mediated regulation of AChE results in the reappearance of high AChE activity in the sarcoplasm of the muscle fibers.

What cooks with solar neutrinos?

Two desperate explanations of the solar neutrino puzzle are proposed, one involving experimental nuclear physics and the other theoretical solar structure and evolution.

Galactic cosmic ray origin of Li, Be and B in stars.

A study of the implications of the hypothesis that high energy processes involving cosmic rays acting on the interstellar medium are the sources of the elements Li, Be and B present in stellar atmospheres and in the solar system.