The main theme of the book Fine Structures of Hyperbolic Diffeomorphisms, by Pinto, Rand and Ferreira, is the rigidity and flexibility of two-dimensional diffeomorphisms on hyperbolic basic sets and properties of invariant measures that are related to the geometry of these invariant sets. In his remarkable article [23], Smale sets the foundations of the modern theory of dynamical systems. He de...

■ Abstract Important physical processes on the Sun, and especially in sunspots, occur on spatial scales at or below the limiting resolution of current solar telescopes. Over the past decade, using a number of new techniques, high-resolution observations have begun to reveal the complex thermal and magnetic structure of a sunspot, along with associated flows and oscillations. During this time re...

Under the expectation that experiments will soon give values for the 6ne structure intervals of the 2'I" state of helium to an accuracy of 1/10', we have undertaken a program of calculations which, it is hoped, will lead to a new determination of the 6ne-structure constant n. This paper gives a brief survey of the over-all program, and a detailed report of the successful completion of the', 6rs...

Though the dictyosome of the Golgi apparatus appears to be generally distributed in plant and animal cells, it is here described for the first time in the fungi. The present report illustrates, in electron micrographs of thin sections, the characteristic structure of the Golgi dictyosome in a special cell type of a supporting pseudo-tissue (the inner ectal excipulum) of a highly evolved Ascomyc...

The mitotic, micronuclear division of the heterotrichous genus Blepharisma has been studied by electron microscopy. Dividing ciliates were selected from clone-derived mass cultures and fixed for electron microscopy by exposure to the vapor of 2 % osmium tetroxide; individual Blepharisma were encapsulated and sectioned. Distinctive features of the mitosis are the presence of an intact nuclear en...