We assume a flat brane located at y = 0, surrounded by an AdS space, and consider the 5D Einstein equations when the energy flux component of the energy-momentum tensor is related to the Hubble parameter through a constant Q. We calculate the metric tensor, as well as the Hubble parameter on the brane, when Q is small. As a special case, if the brane is tensionless, the influence from Q on the Hubble parameter is absent. We also consider the emission of gravitons from the brane, by means of the Boltzmann equation. Comparing the energy conservation equation derived herefrom with the energy conservation equation for a viscous fluid on the brane, we find that the entropy change for the fluid in the emission process has to be negative. This peculiar effect is related to the fluid on the brane being a non-closed thermodynamic system. The negative entropy property for non-closed systems is encountered in other areas in physics also, in particular, in connection with the Casimir effect at finite temperature.

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SUMMARYThe acronym CSEM has widely become synonymous for frequency domain Controlled Source ElectroMagnetics with seabed nodes and horizontal towed dipole transmitters. While this incarnation of marine CSEM is certainly the best known CSEM variant, it is not necessarily always the best option for acquisition over a certain prospect. Based on numerical modelling the differences between horizontal FD CSEM and vertical TD CSEM for given models were explored. The results show that time domain CSEM with vertical transmitter and vertical receiver dipoles is a viable alternative that provides high sensitivity, high depth of penetration as well as low disturbance by air wave and 3D structures. It's much smaller transmitter receiver distance creates an advantage in lateral resolution as well as in the detection of narrower or smaller structures. Case studies with comparisons between inverted vertical-vertical CSEM data and well log results show the real world usefulness of the method as well as the necessity for close integration of the results with other geophysical data. We argue that the marine CSEM landscape will become more divers and that acquisition layout and methodology for a given target needs to be evaluated on a case by case basis to achieve optimum results.