The generalized Liouville equation is studied in a new light using the Lie derivative of a differential form with respect to a vector field.

This paper defends the view of continuants as 'four-dimensional worms' against an argument of Geach's. This is to the effect that if continuants are four-dimensional worms then their stages either do, or do not, fall under the very general terms satisfied by the continuants themselves (a stage of a man either is, or is not, a man); but that either alternative is untenable. I try to show how the former alternative may be defended by appealing to some of Geach's own (...) ideas about identity; then go on to defend the four-dimensionalist view from a criticism of it by Mellor, and finish with an account of the intuitive distinction between process and continuant terms. (shrink)

Quantum entanglement has been focus of fundamental debate since the original paper of Einstein, Podolsky and Rosen [1] and the work of Bell [2], discussing its implications on fundamental issues related to the concepts of physical reality and locality. It has only been during the last few years when it has been recognized that this feature of Quantum Mechanics may also have important applications in the fields of communication and computation. In particular, it has been shown that using entanglement would (...) allow to perform certain computational tasks, such as factoring, much faster. On the other hand, it provides the basis for provably secure secret communication and cryptography. (shrink)