Rocket UV Flash Spectra from the Solar Eclipse of March 7, 1970

Flash spectra of the total solar eclipse throughout all its phases have been obtained in the extreme ultraviolet for the first time.

ELECTRON MICROSCOPY OF THE LICHEN PHYSCZA AZPOLIA (EHRH.) NYL.(1,2)

The ultrastructure of the lichen Physcia aipolia was studied in the desiccated and hydrated states. No significant structural variation between these 2 states was noted for the fungus. The fungus contains unusual ellipsoidal structures heretofore unobserved. Their possible role in the formation of membrane is discussed. The plasmalemma of the fungus is convoluted while that of the alga is smooth. The convoluted projections have a "double-unit membrane" structure similar to fingerlike projections of the ellipsoidal bodies. With Os O4 fixation crystals are pre-served, enclosed in unit membrane sacs which extend to the convoluted surface. The pyrenoid of the associated alga does not produce starch in the desiccated condition, and electron-dense granules are present in the matrix associated with chloroplast lamellae which enter this area. In the hydrated condition, the alga contains abundant starch in the pyrenoid region, and the electron-dense granules are displaced to the preriphery of the pyrenoid starch. Mitochondria, endo-plasmic reticulum, and ribosomes are not clearly defined in the desiccated state while they are more so in the hydrated condition. Golgi bodies were not observed in the either lichen component. Finally, no fine structural basis for indicating an exchanged of materials between the alga and fungus was observed except, possibly, the convoluted plasmalemma of the fungus and the smooth plasmalemma of the alga.

Adaptive automatic correction in optical design

An adaptive technique for optical design with computers is described Its distinctive features are compared with those of the well known damped least squares (DLS) method. The system of adaptive control ensures a particularly certain and rapid convergence, often of an order of magnitude quicker than the DLS method. The convergence is illustrated for a number of examples. The adaptive method enables the designer to learn the fundamental potentialities and limitations of a given optical system.