11 research outputs found

    About Bianchi I with VSL

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    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 cc-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 cc 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 i=13αi=1\sum_{i=1}^{3}\alpha_{i}=1 and i=13αi2<1,\sum_{i=1}^{3}\alpha_{i}^{2}<1, ω\forall\omega, i.e. for all equation of state,, relaxing in this way the Kasner conditions. The behavior of GG depends on two parameters, the equation of state ω\omega and ϵ,\epsilon, a parameter that controls the behavior of c(t),c(t), therefore GG 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 cc-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 II with time varying constants. Self-similar approach

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    We study a perfect fluid Bianchi II models with time varying constants under the self-similarity approach. In the first of the studied model, we consider that only vary GG and Λ.\Lambda. The obtained solution is more general that the obtained one for the classical solution since it is valid for an equation of state ω(1,)\omega\in(-1,\infty) while in the classical solution ω(1/3,1).\omega\in(-1/3,1) . Taking into account the current observations, we conclude that GG must be a growing time function while Λ\Lambda is a positive decreasing function. In the second of the studied models we consider a variable speed of light (VSL). We obtain a similar solution as in the first model arriving to the conclusions that cc must be a growing time function if Λ\Lambda is a positive decreasing function.Comment: 10 pages. RevTeX

    The ecology of the European badger (Meles meles) in Ireland: a review

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    peer-reviewedThe badger is an ecologically and economically important species. Detailed knowledge of aspects of the ecology of this animal in Ireland has only emerged through research over recent decades. Here, we review what is known about the species' Irish populations and compare these findings with populations in Britain and Europe. Like populations elsewhere, setts are preferentially constructed on south or southeast facing sloping ground in well-drained soil types. Unlike in Britain, Irish badger main setts are less complex and most commonly found in hedgerows. Badgers utilise many habitat types, but greater badger densities have been associated with landscapes with high proportions of pasture and broadleaf woodlands. Badgers in Ireland tend to have seasonally varied diets, with less dependence on earthworms than some other populations in northwest Europe. Recent research suggests that females exhibit later onset and timing of reproductive events, smaller litter sizes and lower loss of blastocysts than populations studied in Britain. Adult social groups in Ireland tend to be smaller than in Britain, though significantly larger than social groups from continental Europe. Although progress has been made in estimating the distribution and density of badger populations, national population estimates have varied widely in the Republic of Ireland. Future research should concentrate on filling gaps in our knowledge, including population models and predictive spatial modelling that will contribute to vaccine delivery, management and conservation strategies.Department of Agriculture, Fisheries and FoodTeagasc Walsh Fellowship Programm

    Unique characteristics of neonatal classical conditioning: The role of the amygdala and locus coeruleus

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