(n+1)-dimensional spherically symmetric expanding structures in R2-gravity

In this work, we consider higher-dimensional structures in [Formula: see text]-gravity in an expanding background. We assume a Ricci scalar constant background and use this assumption as the basic constraint to find solutions. Two classes of solutions are presented in which every one includes naked singularity and wormhole geometries. Both classes of solutions show inflationary phase of expansion favored by recent acceleration of the universe. Traversability of the wormhole solutions is discussed. The possibility of satisfying or violating the weak energy condition (WEC) for wormholes is explored. For one class of solutions, particular choices of constants result in wormholes which satisfy the WEC all over the spacetime.

Characteristics of the Flow of an Ionized Perfect Gas Through a Magnetic Field

The problem of the compressible flow of a perfect gas with constant fractional ionization through a magnetic field is considered. The Joulean heat dissipation is assumed to be taken out of the gas so that the flow can be treated as isentropic. The present analysis differs slightly from others previously reported in the literature [1, 2, 3, 4] mainly in that the entire conductivity tensor and the variation of its elements with gas properties are taken into account. It is felt that the somewhat unrealistic condition of isentropic flow is much less restrictive than the assumption of a scalar constant conductivity. Under these conditions, a relatively simple integration of the flow equations is possible. The assumption of isentropic flow implies that the difference in stagnation enthalpies at the entrance and exit of the magnetic field region is equal to the electrical output plus the Joulean heat. Therefore the ratio of the output power to the difference in stagnation enthalpies gives a measure of the Joulean heat dissipation and hence of the efficiency of the device.

Certain Expansions in the Algebra of Quantum Mechanics

§ 1. Introduction. The algebra of quantum mechanics is characterized by the fact that the variables p, q obey all the laws of ordinary algebra except that multiplication is non-commutative and instead there exists a relation of the formwhere c is a real or complex scalar constant and is thus commutative with both p and q.