Building on the work of Morris, Thorne, and Yurtsever, some particularly simple examples of traversable wormholes are exhibited. These examples are notable both because the analysis is not limited to spherically symmetric cases, and because it is possible to in some sense minimize the use of exotic matter. In particular, it is possible for a traveller to traverse such a wormhole without passing...

This paper provides a brief overview of three recent contributions to robot learning developed by researchers at the University of Massachusetts Amherst. The first is the use of policy search algorithms that exploit new techniques in nonparameteric heteroscedastic regression to directly model policy-dependent distribution of cost [12]. Experiments demonstrate dynamic stabilization of a mobile m...

Democracy: Marx’s theory of history (ex. Organization of the mode of production determines superstructure; unequal distribution of labor) explains the lack of actual democracy in capitalist societies; however, Marx’s thought concerning progression (also a theory of history) states that capitalist societies would eventually progress to a democratic state after a revolution of the proletariat. Ma...

In this note we discuss some symmetry groups as nice examples of group extensions. We begin by a short general discussion of symmetry groups. An isometry of R is a distancepreserving bijection of R. For examples of isometries, translations by a vector, rotations about a point, and reflections about a hyperplane are all isometries. Let Isom(R) be the set of all isometries of R. This is a group u...

O ne definition of "holism" is "lhe theory that whole entities, as fundamental components of reality, have an existence olher Ihan Ihe mere sum of their parts" , Ihe term "whole" being defined as referring to "an assemblage of parts associated or viewed as one thing". Environmental activists and many I scientists nowadays stress the need, when studying ecosystems (e.g., coral reefs or estuaries...