EGG maturation in Limnaea stagnalis has been described by Raven (1945, 1949). It exhibits some peculiarities, by which the Limnaea egg seemed to stand apart from all other animal eggs in which the maturation processes have been accurately studied so far. In the first place it appeared that the second maturation spindle arises by a direct and gradual transformation of the centrosphere at the inn...

With the advent of electronic documents, information is available in more than just its visual form |electronic information is display-independent. Though the principal mode of display is still visual, we can now produce alternative renderings of this information |we have designed a computing system, ASTER, that produces an audio view. The visual mode of communication is characterized by the sp...

This paper introduces the Aster distributed con guration-based programming system that is aimed at easing the development of emerging distributed applications having quality of service requirements. Our approach is based on high-level customization: given the speci cation of application requirements using the Aster interconnection language, a distributed runtime system, customized for meeting t...

Spontaneous directed motion, a hallmark of cell biology, is unusual in classical statistical physics. Here we study, using both numerical and analytical methods, organized motion in models of the cytoskeleton in which constituents are driven by energy-consuming motors. Although systems driven by small-step motors are described by an effective temperature and are thus quiescent, at higher order ...

Populations are often subject to the effect of catastrophic events that cause mass removal. In particular, metapopulation models, epidemics, and migratory flows provide practical examples of populations subject to dis asters (e.g., habitat destruction, environmental catastrophes). Many stochastic models have been developed to explain the behavior of these populations. Most of the reported resul...

A new guaiane-type sesquiterpene, 4α,7β-dihydroxy-10βH-guai-5-en-1β,8β-endoxide (1), was isolated from Heteropappus altaicus (Compositea). The structure of compound 1, which contains exhibited a rare 1,8-oxide bridge, was established on the basis of spectroscopic data.