Wheeler-DeWitt Equation with Variable Constants

In this paper we study how all the physical "constants" vary in the framework described by a model in which we have taken into account the generalize conservation principle for its stress-energy tensor. This possibility enable us to take into account the adiabatic matter creation in order to get rid of the entropy problem. We try to generalize this situation by contemplating multi-fluid components. To validate all the obtained results we explore the possibility of considering the variation of the"constants" in the quantum cosmological scenario described by the Wheeler-DeWitt equation. For this purpose we explore the Wheeler-DeWitt equation in different contexts but from a dimensional point of view. We end by presenting the Wheeler-DeWitt equation in the case of considering all the constants varying. The quantum potential is obtained and the tunneling probability is studied.Comment: 17 pages. New section

Brachypotherium aurelianense (NOUEL)(Perissodactyla, Rhinocerotidae) del Mioceno inferior continental valenciano (Buñol, Valencia)

En esta nota se cita por primera vez la presencia de Brachypothcrium aurelianense en el Orleaniense de Buñol (Valencia). Se describen las escasas piezas atribuibles a esta especie y se comparan con otros Rinocerdtidos estratigrAficamente próximos. Continuamos utilizando la denominacidn de B. aurelianense ya que consideramos que las pruebas aducidas por Antunes et Ginsburg (1983) no son suficientes para que la especie de NOUEL deba considerarse como Diaceratheriurn

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

Bulk Viscosity Effects on the Early Universe Stability

We present a discussion of the effects induced by the bulk viscosity on the very early Universe stability. The matter filling the cosmological (isotropic and homogeneous) background is described by a viscous fluid having an ultrarelativistic equation of state and whose viscosity coefficient is related to the energy density via a power-law of the form $\zeta=\zeta_0 \rho^\nu$. The analytic expression of the density contrast (obtained for $\nu=1/2$) shows that, for small values of the constant $\zeta_0$, its behavior is not significantly different from the non-viscous one derived by E.M. Lifshitz. But as soon as $\zeta_0$ overcomes a critical value, the growth of the density contrast is suppressed forward in time by the viscosity and the stability of the Universe is favored in the expanding picture. On the other hand, in such a regime, the asymptotic approach to the initial singularity (taken at $t=0$) is deeply modified by the apparency of significant viscosity in the primordial thermal bath i.e. the isotropic and homogeneous Universe admits an unstable collapsing picture. In our model this feature regards also scalar perturbations while in the non-viscous case it appears only for tensor modes.Comment: 8 pages, no figur

Causal Bulk Viscous Dissipative Isotropic Cosmologies with Variable Gravitational and Cosmological Constants

We consider the evolution of a flat Friedmann-Robertson-Walker Universe, filled with a causal bulk viscous cosmological fluid, in the presence of variable gravitational and cosmological constants. The basic equation for the Hubble parameter, generalizing the evolution equation in the case of constant gravitational coupling and cosmological term, is derived, under the supplementary assumption that the total energy of the Universe is conserved. By assuming that the cosmological constant is proportional to the square of the Hubble parameter and a power law dependence of the bulk viscosity coefficient, temperature and relaxation time on the energy density of the cosmological fluid, two classes of exact solutions of the field equations are obtained. In the first class of solutions the Universe ends in an inflationary era, while in the second class of solutions the expansion of the Universe is non-inflationary for all times. In both models the cosmological "constant" is a decreasing function of time, while the gravitational "constant" increases in the early period of evolution of the Universe, tending in the large time limit to a constant value.Comment: 14 pages, 15 figure

About Bianchi I with VSL

In this paper we study how to attack, through different techniques, a perfect fluid Bianchi I model with variable G,c and Lambda, but taking into account the effects of a $c$-variable into the curvature tensor. We study the model under the assumption,div(T)=0. These tactics are: Lie groups method (LM), imposing a particular symmetry, self-similarity (SS), matter collineations (MC) and kinematical self-similarity (KSS). We compare both tactics since they are quite similar (symmetry principles). We arrive to the conclusion that the LM is too restrictive and brings us to get only the flat FRW solution. The SS, MC and KSS approaches bring us to obtain all the quantities depending on \int c(t)dt. Therefore, in order to study their behavior we impose some physical restrictions like for example the condition q<0 (accelerating universe). In this way we find that $c$ is a growing time function and Lambda is a decreasing time function whose sing depends on the equation of state, w, while the exponents of the scale factor must satisfy the conditions $\sum_{i=1}^{3}\alpha_{i}=1$ and $\sum_{i=1}^{3}\alpha_{i}^{2}<1,$ $\forall\omega$, i.e. for all equation of state$,$ relaxing in this way the Kasner conditions. The behavior of $G$ depends on two parameters, the equation of state $\omega$ and $\epsilon,$ a parameter that controls the behavior of $c(t),$ therefore $G$ may be growing or decreasing.We also show that through the Lie method, there is no difference between to study the field equations under the assumption of a $c-$var affecting to the curvature tensor which the other one where it is not considered such effects.Nevertheless, it is essential to consider such effects in the cases studied under the SS, MC, and KSS hypotheses.Comment: 29 pages, Revtex4, Accepted for publication in Astrophysics & Space Scienc

Bianchi I with variable GG and Λ\Lambda. Self-Similar approach

In this paper we study how to attack under the self-similarity hypothesis a perfect fluid Bianchi I model with variable $G,$and $\Lambda,$ but under the condition $\operatorname{div}T\neq0.$ We arrive to the conclusion that: $G$ and $\Lambda$ are decreasing time functions (the sing of $\Lambda$ depends on the equation of state), while the exponents of the scale factor must satisfy the conditions $\sum_{i=1}^{3}\alpha_{i}=1$ and $\sum_{i=1}^{3}\alpha_{i}^{2}<1,$ $\forall\omega\in(-1,1) ,$ relaxing in this way the Kasner conditions. We also show the connection between the behavior of $G$ and the Weyl tensor.Comment: 15 pages. accepted in IJMP

Archosaurian teeth (Crocodyliformes, Theropoda) from the Late Jurassic of BuÒol (Valencia province, E Spain)

[EN] Five isolated archosaurian teeth from Valencia province (eastern Spain) are studied in this work. They have been found in the ¿Cantera CarcalÌnª site, an outcrop of the marine Higueruelas Formation (Tithonian) in the vicinity of BuÒol town. They represent the first direct evidence of tetrapods in this formation, in which, up to the moment, only dinosaur tracks had been found in a locality of the adjacent Teruel province. Four of the teeth pertain to crocodyliforms, three to indeterminate crocodyliforms and another to a teleosaurid identified as cf. Machimosaurus sp., a taxon already known in the Kimmeridgian of the Iberian Peninsula (Asturias and Portugal). The fifth tooth is assigned to a theropod dinosaur, probably an allosauroid.El equipo de investigación del MUJA está subvencionado por el Protocolo de colaboración CN-04-226 entre la Consejería de Cultura y Turismo del Principado de Asturias y la Universidad de Oviedo. Este trabajo es una contribución a los proyectos CGL2007-62469/BTE(J.I.R-O) y CGL2007-64061/BTE (X.P.S,J.C.) del Ministerio de Ciencia e Innovación, y del grupo de investigación del Gobierno Vasco GIC07/14-361 (X.P.S.).Agradecemos a José Ignacio Canudo (Universidad de Zaragoza) y Francisco Ortega (UNED) la revisión crítica del manuscritoRuiz-Omeñaca, JI.; Pereda-Suberbiola, X.; Company Rodríguez, J.; Belinchón, M. (2010). Dientes de arcosaurios (Crocodyliformes, Theropoda) del Jurásico Superior de Buñol (Valencia). Geogaceta. 48:35-38. http://hdl.handle.net/10251/150323S35384

Generalized Self-similar Scalar-Tensor Theories

We study through symmetry principles the form of the functions in the generalizated scalar-tensor theories under the self-similar hypothesis. The results obtained are absolutely general and valid for all the Bianchi models and the flat FRW one. We study the concrete example of the Kantowsky-Sach model finding some exact self-similar solutions.Comment: 21 pages. Typos corrected. References added, minor correction