Epimorphisms of C*-algebras are surjective

We answer a question raised by V.G.Pestov in the affirmative.Comment: 2 page

F-adjunction

In this paper we study singularities defined by the action of Frobenius in characteristic $p > 0$. We prove results analogous to inversion of adjunction along a center of log canonicity. For example, we show that if $X$ is a Gorenstein normal variety then to every normal center of sharp $F$-purity $W \subseteq X$ such that $X$ is $F$-pure at the generic point of $W$, there exists a canonically defined \bQ-divisor $\Delta_{W}$ on $W$ satisfying (K_X)|_W \sim_{\bQ} K_{W} + \Delta_{W}. Furthermore, the singularities of $X$ near $W$ are "the same" as the singularities of $(W, \Delta_{W})$. As an application, we show that there are finitely many subschemes of a quasi-projective variety that are compatibly split by a given Frobenius splitting. We also reinterpret Fedder's criterion in this context, which has some surprising implications.Comment: 31 pages; to appear in Algebra and Number Theory. Typos corrected, presentation improved throughout. Section 7 subdivided into two sections (7 and 8). The proofs of 4.8, 5.8 and 9.5 improve

Detection of Gravitational Waves from Eccentric Compact Binaries

Coalescing compact binaries have been pointed out as the most promising source of gravitational waves for kilometer-size interferometers such as LIGO. Gravitational wave signals are extracted from the noise in the detectors by matched filtering. This technique performs really well if an a priori theoretical knowledge of the signal is available. The information known about the possible sources is used to construct a model of the expected waveforms (templates). A common assumption made when constructing templates for coalescing compact binaries is that the companions move in a quasi-circular orbit. Some scenarios, however, predict the existence of eccentric binaries. We investigate the loss in signal-to-noise ratio induced by non-optimal filtering of eccentric signals.Comment: 5 pages, 2 figures, to appear in the proceedings of the 8th Canadian Conference on General Relativity and Relativistic Astrophysic