The gravitational field of a particle of small mass m moving through curved spacetime, with metric gab, is naturally and easily decomposed into two parts each of which satisfies the perturbed Einstein equations through O(m). One part is an inhomogeneous field hab which, near the particle, looks like the Coulomb m/r field with tidal distortion from the local Riemann tensor. This singular field i...

The equations of motion for matter fields are invariant under the shift of the matter lagrangian by a constant. Such a shift changes the energy momentum tensor of matter by T a b → T a b + ρδ a b . In the conventional approach, gravity breaks this symmetry and the gravitational field equations are not invariant under such a shift of the energy momentum tensor. I argue that until this symmetry i...

1997 ist in der GLDV der Arbeitskreis Texttechnologie gegründet worden (vgl. http://www.uni-giessen.de/~g91062/GLDV/). Der Arbeitskreis hat unter anderem das Ziel, den Teilnehmerinnen und Teilnehmern einen Überblick über Aktivitäten zu verschaffen, die zum Thema SGML/XML in der linguistischen Datenverarbeitung von GLDV-Mitgliedern durchgeführt werden (dazu gab es im März ein erstes Arbeitstreff...

We show that the matrix-model action for noncommutative U(n) gauge theory actually describes SU(n) gauge theory coupled to gravity. This is elaborated in the 4-dimensional case. The SU(n) gauge fields as well as additional scalar fields couple to an effective metric Gab, which is determined by a dynamical Poisson structure. The emergent gravity is intimately related to noncommutativity, encodin...

It is argued that the symmetry algebra of asymptotically flat spacetimes at null infinity in 4 dimensions should be taken as the semi-direct sum of supertranslations with infinitesimal local conformal transformations and not, as usually done, with the Lorentz algebra. As a consequence, two dimensional conformal field theory techniques will play as fundamental a role in this context of direct ph...

The Australian Great Artesian Basin (GAB) supports a unique and diverse range of ecologically significant groundwater-fed wetland ecosystems termed GAB springs. The springs are of great national and international importance for their ecological, scientific and economic values, and are culturally significant to indigenous Australians. The ecological sustainability of the springs has become uncer...

The Diffie-Hellman protocol was one of the first methods discovered for two people, say Alice and Bob, to agree on a shared secret key despite the fact that any of the messages sent between the two of them might be intercepted. That is, the goal of the protocol is to make it impossible to determine the shared secret key for some third party, say Eve, who sees all the communication between Alice...

We investigate the Cohen-Macaulay property for rings of invariants under multiplicative actions of a finite group G. By definition, these are G-actions on Laurent polynomial algebras k[x 1 , . . . , x ±1 n ] that stabilize the multiplicative group consisting of all monomials in the variables xi. For the most part, we concentrate on the case where the base ring k is Z. Our main result states tha...