Full Causal Bulk Viscous Cosmologies with time-varying Constants

We study the evolution of a flat Friedmann-Robertson-Walker Universe, filled with a bulk viscous cosmological fluid, in the presence of time varying ``constants''. The dimensional analysis of the model suggests a proportionality between the bulk viscous pressure of the dissipative fluid and the energy density. On using this assumption and with the choice of the standard equations of state for the bulk viscosity coefficient, temperature and relaxation time, the general solution of the field equations can be obtained, with all physical parameters having a power-law time dependence. The symmetry analysis of this model, performed by using Lie group techniques, confirms the unicity of the solution for this functional form of the bulk viscous pressure. In order to find another possible solution we relax the hypotheses assuming a concrete functional dependence for the ``constants''.Comment: 28 pages, RevTeX

Global existence for the confined muskat problem

In this paper we show global existence of the Lipschitz continuous solution for the stable Muskat problem with finite depth (confined) and initial data satisfying some smallness conditions relating the amplitude, the slope, and the depth. The cornerstone of the argument is that, for these small initial data, both the amplitude and the slope remain uniformly bounded for all positive times. We notice that, for some of these solutions, the slope can grow but it remains bounded. This is very different from the infinite deep case, where the slope of the solutions satisfy a maximum principle. Our work generalizes a previous result where the depth is infinite. © 2014 Society for Industrial and Applied Mathematics.The author was supported by the grant MTM2011-26696 and SEV-2011-0087 from Ministerio de Economía y Competitividad (MINECO

Two restrictions in the theories that include G(t) and c(t) varying with time

Much work has been done taking into account the possibility that the gravitational {\it constant} $G$ may vary with cosmological time $t$ (or with the cosmological scale factor $a(t)$). In many of these works the speed of light $c$ is not addressed or is taken as constant (see for example the Dirac large number hypothesis, \cite{Dirac}). The same can be said of many works that assume the speed of light $c$ to vary with cosmological time $t$ or $a(t)$ (see for example \cite{ MaMo}). Again in many of these works the gravitational constant $G$ is not addressed or is taken as constant. We have two important remarks on these assumptions.Fullana Alfonso, MJ.; Alfonso-Faus, A. (2014). Two restrictions in the theories that include G(t) and c(t) varying with time. Astrophysics and Space Science. 350(2):781-783. doi:10.1007/s10509-014-1803-4S7817833502Belinchón, J.A., Alfonso-Faus, A.: A theory of time-varying constants. Int. J. Mod. Phys. D 10, 299 (2001). Preprint: arXiv:gr-qc/0404044Dirac, P.A.M.: The cosmological constants. Nature 139, 323 (1937)Magueijo, J., Moffat, J.W.: Comments on “Note on varying speed of light theories”. Gen. Relativ. Gravit. 40, 1797 (2008). Preprint: arXiv:0705.450

Detection of Leishmania infantum kinetoplast DNA by Real Time PCR in hair of wild rabbits

The study of potential wild mammal reservoirs is necessary for the surveillance of leishmaniosis, as Leishmania protozoans have been isolated from a wide range of wild and domestic animal species, including Leporidae. Recently, it has been demonstrated that both hares and wild rabbits can act as sylvatic reservoirs of Leishmania. In Spain, most of the research involving wild rabbits has been developed in the central area of Madrid and in the southeastern Mediterranean coast. We studied the presence of Leishmania infantum in 116 wild rabbits (Oryctolagus cuniculus) captured in Santovenia de Pisuerga, Valladolid, Spain. Hair samples were analyzed by real time PCR. L. infantum kinetoplast DNA (kDNA) was detected and quantified in 4 out of 116 analyzed animals. The estimated number of parasites obtained were quite variable, ranging from 2.60 to 276.60. Hair samples can be collected by non-invasive methods, being a proper sample for Leishmania detection in wild Leporidae, which have an important role as reservoirs of Leishmania. Our findings enhance the need for more extensive studies in different geographical areas.S

Exact solutions of a Flat Full Causal Bulk viscous FRW cosmological model through factorization

We study the classical flat full causal bulk viscous FRW cosmological model through the factorization method. The method shows that there exists a relationship between the viscosity parameter $s$ and the parameter $\gamma$ entering the equations of state of the model. Also, the factorization method allows to find some new exact parametric solutions for different values of the viscous parameter $s$. Special attention is given to the well known case $s=1/2$, for which the cosmological model admits scaling symmetries. Furthermore, some exact parametric solutions for $s=1/2$ are obtained through the Lie group method.Comment: 18 pas. RevTeX4. New solutions. arXiv admin note: text overlap with arXiv:gr-qc/0107004 by other author