Four-dimensional gravity on supersymmetric dilatonic domain walls

We investigate the localization of four-dimensional metastable gravity in supersymmetric dilatonic domain walls through massive modes by considering several scenarios in the model. We compute corrections to the Newtonian potential for small and long distances compared with a crossover scale given in terms of the dilatonic coupling. 4D gravity behavior is developed on the brane for distance very much below the crossover scale, while for distance much larger, the 5D gravity is recovered. Whereas in the former regime gravity is always attractive, in the latter regime due to non-normalizable unstable massive graviton modes present on the spectrum, in some special cases, gravity appears to be repulsive and signalizes a gravitational confining phase which is able to produce an inflationary phase of the Universe.Comment: 11 pages, 4 figures, Latex. Version to appear in PL

Domain wall description of superconductivity

In the present work we shall address the issue of electrical conductivity in superconductors in the perspective of superconducting domain wall solutions in the realm of field theory. We take our set up made out of a dynamical complex scalar field coupled to gauge field to be responsible for superconductivity and an extra scalar real field that plays the role of superconducting domain walls. The temperature of the system is interpreted through the fact that the soliton following accelerating orbits is a Rindler observer experiencing a thermal bath.Comment: 9 pages, 5 figures, Latex. Version to appear in PL

Relaxing to a three dimensional brane junction

We suggest a mechanism which leads to 3+1 space-time dimensions. The Universe assumed to have nine spatial dimensions is regarded as a special nonlinear oscillatory system -- a kind of Einstein solid. There are p-brane solutions which manifest as phase oscillations separating different phase states. The presence of interactions allows for bifurcations of higher dimensional spaces to lower dimensional ones in the form of brane junctions. We argue this is a natural way to select lower dimensions.Comment: RevTex, 5 pages; version to appear in Europhys. Let

Cosmology in the Universe with distance dependent Lorentz-violating bakground

We consider a cosmological setup with the inflaton field in the presence of a redshift dependent Lorentz-violating time-like background to address the inflationary regime and other phases of the Universe. We also show that the regime of dark energy at large distances (low redshifts) is essentially dominated by the presence of the Lorentz-violating background.Comment: 8 pages, no figure, Latex, to appear in AHE

Fate of protozoa during the start-up of a sequencing batch biofilm reactor used for the degradation of hydrocarbons

Large amounts of oily sludges are retained in patrol stations by gravity interceptors in order to prevent their discharge in surface waters. Those residues are mainly composed of a mixture of hydrocarbons, water and inert solids. Therefore, their final disposal represents a significant environmental problem. This work concerns the study of microfauna biomass during the start-up of a SBBR designed for the treatment of hydrocarbon slurries retained in an API oil separator. The findings of this study suggest that protozoal colonization of the SBBR followed the same pattern of activated sludge systems, the free swimming and crawling ciliates, and also fagellates being the dominant protozoa group during the star-up period of the reactor. When the plant performance dropped, the number of flagellated protozoa rapidly increased, and a concomitant decrease in the ciliated population was observed.Fundação para a Ciência e a Tecnologia (FCT)

Effect of the surfactants tween 20 and CTAB on fluoranthene and anthracene degradation by P. putida

The effect of a nonionic and a cationic surfactant, Tween 20 and CTAB, on the biodegradation rate of fluoranthene and anthracene by a P. putida strain was investigated. Tween 20 had a positive effect on the biodegradation rate of anthracene. However, it did not affect significantly fluoranthene oxidation. The cationic surfactant CTAB inhibited the oxidation of both PAHs, fluoranthene and anthracene

Fluctuation-Induced Casimir Forces in Granular Fluids

We have numerically investigated the behavior of driven non-cohesive granular media and found that two fixed large intruder particles, immersed in a sea of small particles, experience, in addition to a short range depletion force, a long range repulsive force. The observed long range interaction is fluctuation-induced and we propose a mechanism similar to the Casimir effect that generates it: the hydrodynamic fluctuations are geometrically confined between the intruders, producing an unbalanced renormalized pressure. An estimation based on computing the possible Fourier modes explains the repulsive force and is in qualitative agreement with the simulations.Comment: 4 pages, 3 figures. Accepted in Phys. Rev. Letter