Quantum treatment and equation of state of a Friedmann-Robertson-Walker brane embedded in a five dimensional fluid bulk

In the present paper, we deal with the five dimensional warped k=0–FRW Universe, with a perfect fluid in the bulk. By solving the Einstein’s Equations, we get the corresponding scale function, a, and the warp factor. Particular attention is given to the effective potential V(a), which is used in solving both the Wheeler-DeWitt equation and the stationary Schrödinger equation. Inspired by similar considerations carried out in a series of recent papers, we assume that the brane matter is made of two interacting perfect fluids. We compute the corresponding densities and pressures and write down the Equation of State, whose dynamic parameter is taking all the intermediate values, from w=1, at t=0, to w=?1, in the far future.     

Approximative analytic study of fermions in magnetar’s crust; ultra-relativistic plane waves, Heun and Mathieu solutions and beyond

Working with a magnetic field periodic along Oz and decaying in time, we deal with the Dirac-type equation characterizing the fermions evolving in magnetar’s crust. For ultra-relativistic particles, one can employ the perturbative approach, to compute the conserved current density components. If the magnetic field is frozen and the magnetar is treated as a stationary object, the fermion’s wave function is expressed in terms of the Heun’s Confluent functions. Finally, we are extending some previous investigations on the linearly independent fermionic modes solutions to the Mathieu’s equation and we discuss the energy spectrum and the Mathieu Characteristic Exponent.     

Solutions for Massless Bosons in the Mannheim-Kazanas Space-Time

Astrophysics - The present paper deals with the Mannheim-Kazanas metric which is supposed to offer a reliable explanation on the observed galaxy rotation curves. The effective potential and the...     

Five-dimensional anti-de Sitter bulk with oscillating Friedmann–Robertson–Walker branes

We propose a toy model for the five dimensional warped FRW universe of zero spatial curvature, with a stiff matter source in the bulk, whose scale function corresponds to an oscillating brane, with negative acceleration parameter. By considering the matter in the four-dimensional brane as being composed of two coupled perfect fluids, we discuss the form of the interacting term allowing energy exchange between the two fluids. Finally, special attention is given to three cases related to the chronology of the universe and the corresponding densities and pressures are calculated, pointing out non-trivial contributions coming from the fifth dimension.     

Paleolakes, paleofloods, and depressions in Aurorae and Ophir Plana, Mars: Connectivity of surface and subsurface hydrological systems

The plains of Aurorae and Ophir in the equatorial region of Mars display geomorphic evidence indicative of extensive but generally short-lived paleohydrological processes. Elaver Vallis in Aurorae Planum south of Ganges Chasma is an outflow channel system >180 km long, and here inferred to have formed by cataclysmic spillover flooding from a paleolake(s) contained in the Morella crater basin. Ganges Cavus is an enormous 5-km-deep depression of probable collapse origin located in the Morella basin. The fluid responsible for the infilling of the Morella basin likely emerged at least partially through Ganges Cavus or its incipient depression, and it may have been supplied also from small-scale springs in the basin. Similar paleohydrological processes are inferred also in Ophir Planum. It is reasonable to assume that water, sometimes sediment-laden and/or mixed with gases, was the responsible fluid for these phenomena although some of the observed features could be explained by non-aqueous processes such as volcanism. Water emergence may have occurred as consequences of ground ice melting or breaching of cryosphere to release water from the underlying hydrosphere. Dike intrusion is considered to be an important cause of formation for the cavi and smaller depressions in Aurorae and Ophir Plana, explaining also melting of ground ice or breaching of cryosphere. Alternatively, the depressions and crater basins may have been filled by regional groundwater table rising during the period(s) when cryosphere was absent or considerably thin. The large quantities of water necessary for explaining the paleohydrological processes in Aurorae and Ophir Plana could have been derived through crustal migration from the crust of higher plains in western Ophir Planum where water existed in confined aquifers or was produced by melting of ground ice due to magmatic heating or climatic shift, or from a paleolake in Candor Chasma further west.     

Measurement of radon potential from soil using a special method of sampling

Soil radon gas and/or its exhalation rate are used as indicators for some applications, such as uranium exploration, indoor radon concentration, seismic activity, location of subsurface faults, etc., and also in the studies where the main interest is the field verification of radon transport models. This work proposes a versatile method for the soil radon sampling using a special manner of pumping. The soil gas is passed through a column of charcoal by using passive pumping. A plastic bottle filled with water is coupled to an activated charcoal column and the flow of water through an adjustable hole made at the bottom of bottle assures a controlled gas flow from the soil. The results obtained for the activity of activated charcoal are in the range of 20–40 kBq/m³, for a depth of approximately 0.8 m. The results obtained by this method were confirmed by simultaneous measurements using LUK 3C device for soil radon measurements. Possible applications for the estimation of radon soil potential are discussed.