Let’s move to Venus

To move or not to move.

Semaphorins were discovered 11 years ago as molecular cues for axon guidance that are conserved from invertebrates to humans. More than 20 semaphorin genes have been identified in mammals and their protein products are now known to be involved in a range of processes from the guidance of cell migration to the regulation of the immune response, angiogenesis and cancer. Plexins, either alone or i...

Constructability of Trip-lets

A trip-let is an object as shown on the cover of Hofstadter’s book Gödel, Escher, Bach: a solid, threedimensional object that, when viewed from three orthogonal directions, shows three different letters. In this paper we consider two problems related to the construction of such objects for a given set of three letters. First, we want to know whether the silhouettes of the object correspond to t...

On Desugaring Polymorphic Lets

Existing type literature has conflicting views on desugaring polymorphic lets to lambda terms. The conflict arises because, in certain cases, desugaring does not preserve typing. We describe a transformation of polymorphic lets to monomorphic lets such that, when the monomorphic lets are desugared, the typing is preserved. Our transformation requires no changes to either term or type syntax. Th...

Venus ® Diamond Venus ® Diamond Flow

Venus.

Mary Ellen Avery Treasurer Francisco J. Ayala Richard S. Nicholson Robert A. Frosch Executive Officer John Abelson Frederick W. Alt Don L. Anderson Stephen J. Benkovic David E. Bloom Floyd E. Bloom Henry R. Bourne James J. Bull Kathryn Calame C. Thomas Caskey Dennis W. Choi John M. Coffin Bruce F. Eldridge Paul T. Englund Richard G. Fairbanks Douglas T. Fearon Harry A. Fozzard Victor R. Fuchs T...