Spatial discretization of restricted group algebras

We consider spatial discretizations by the finite section method of the restricted group algebra of a finitely generated discrete group, which is represented as a concrete operator algebra via its left-regular representation. Special emphasis is paid to the quasicommutator ideal of the algebra generated by the finite sections sequences and to the stability of sequences in that algebra. For both problems, the sequence of the discrete boundaries plays an essential role. Finally, for commutative groups and for free non-commutative groups, the algebras of the finite sections sequences are shown to be fractal

In-medium Pion-Pion Interaction and Chiral Symmetry Restoration

We discuss medium modifications of the unitarized pion-pion interaction in the nuclear medium. We incorporate both the effects of chiral symmetry restoration and the influence of collective nuclear pionic modes, originating from the p-wave coupling of the pion to delta-hole configurations. We show how the resulting strong enhancement of the sigma-meson spectral function is related to large fluctuations of the condensate associated with the partial restoration of chiral symmetry.Comment: 8 pages, 3 Postscript figures, contribution to the `International Workshop XXVIII on Gross Properties of Nuclei and Nuclear Excitations', Hirschegg, Austria, January 16-22 200

Towards a Flexible Intra-Trustcenter Management Protocol

This paper proposes the Intra Trustcenter Protocol (ITP), a flexible and secure management protocol for communication between arbitrary trustcenter components. Unlike other existing protocols (like PKCS#7, CMP or XKMS) ITP focuses on the communication within a trustcenter. It is powerful enough for transferring complex messages which are machine and human readable and easy to understand. In addition it includes an extension mechanism to be prepared for future developments.Comment: 12 pages, 0 figures; in The Third International Workshop for Applied PKI (IWAP2004

FAA to Test Ability of Foam Beds to Stop Airplanes in Emergencies; UD Researchers Work to Help Develop the Airplane of the Future

Feature leads for the media: Based on computer simulations developed by University of Dayton researchers, the Federal Aviation Administration will conduct tests of foam beds for their ability to stop airplanes without harming passengers; also, UD\u27s Mechanical and Aerospace Engineering Department is conducting research to develop an aerospace plane designed to fly eight times faster than an existing Air Force plane