Thermal and electrical interaction of tantalum with a low temperature chemically active plasma flow

The paper deals with an experimental study of radiative heat transfer and charge transfer processes from the surface of tantalum plates under conditions of unsteady high-temperature heating and oxidation. It is shown that at plate temperatures of 1800 K, the heat flux may be as high as 400 kW/sq m. Heating is shown to stimulate the emissivity of tantalum and the temperature of the free electrons which surface, through a gas boundary layer, from the plasma onto the metal

Gravitational trapping potential with arbitrary extra dimensions

We extend a recently discovered, non-singular 6 dimensional brane, solution to D=4+n dimensions. As with the previous 6D solution the present solution provides a gravitational trapping mechanism for fields of spin 0, 1/2, 1 and 2. There is an important distinction between 2 extra dimensions and $n$ extra dimensions that makes this more than a trivial extension. In contrast to gravity in n >2 dimensions, gravity in n=2 dimensions is conformally flat. The stress-energy tensor required by this solution has reasonable physically properties, and for n=2 and n=3 can be made to asymptotically go to zero as one moves away from the brane.Comment: 7 pages revtex. No figures. References added some discussions change

Models of G time variations in diverse dimensions

A review of different cosmological models in diverse dimensions leading to a relatively small time variation of the effective gravitational constant G is presented. Among them: 4-dimensional general scalar-tensor model, multidimensional vacuum model with two curved Einstein spaces, multidimensional model with multicomponent anisotropic "perfect fluid", S-brane model with scalar fields and two form field etc. It is shown that there exist different possible ways of explanation of relatively small time variation of the effective gravitational constant G compatible with present cosmological data (e.g. acceleration): 4-dimensional scalar-tensor theories or multidimensional cosmological models with different matter sources. The experimental bounds on G-dot may be satisfied ether in some restricted interval or for all allowed values of the synchronous time variable.Comment: 27 pages, Late

Half-Twisted Correlators from the Coulomb Branch

We compute correlators of chiral operators in half-twisted (0,2) supersymmetric gauged linear sigma models. Our results give simple algebraic formulas for a (0,2) generalization of genus zero Gromov-Witten invariants of compact toric varieties. We derive compact expressions for deformed quantum cohomology relations and apply our general method to several examples.Comment: 21 pages, LaTex; typos corrected; some discussion adde