Annular aperture diffracted energy distribution for an extended source.

The annular aperture diffracted energy distribution in the image plane for an extended incoherent source has been calculated and tabulated for source sizes up to five times the size of the Airy disk and for annular aperture ratios up to 0.5. It is shown that for a scanning instrument an increase in the instantaneous field of view from one to two times the Rayleigh limit degrades the effective resolution by a factor significantly less than two.

Glycerol 1,2-cyclic phosphate in centric diatoms. Observation by 31P NMR in vivo, isolation, and structural determination.

We have isolated and identified glycerol 1,2-cyclic phosphate as the compound responsible for a unique prominent resonance at 19.1 ppm in the 31P NMR spectrum in vivo of four species of centric diatoms, where it is responsible for 15 to 30% of the total signals from organophosphates. This appears to be the first observation of this compound as a major metabolite. It was not detectable in nine other species of algae, including four species of pennate diatoms.

Zinc from oyster tissue as causative factor in mouse deaths in official bioassay for paralytic shellfish poison.

Toxicity (extreme weakness, body temperature drop, cyanosis, some slow deaths) in test mice, upon intraperitoneal injection of standard-method paralytic shellfish poison (PSP) extracts of some PSP-free oysters, is consistent with the relatively high levels of zinc in these extracts. As a rough guideline, the threshold for a toxic response corresponds to a drained tissue zinc level of over 900 micrograms/g. The identification of zinc as the substance responsible has been supported by inducing toxicity in control extracts by spiking with nontoxic levels of zinc, and by eliminating toxicity from toxic extracts by chemical removal (precipitation, ion exchange) of metals.