15 research outputs found
Scalar field in the Bianchi I: Non commutative classical and Quantum Cosmology
Using the ADM formalism in the minisuperspace, we obtain the commutative and
noncommutative exact classical solutions and exact wave function to the
Wheeler-DeWitt equation with an arbitrary factor ordering, for the anisotropic
Bianchi type I cosmological model, coupled to a scalar field, cosmological term
and barotropic perfect fluid. We introduce noncommutative scale factors,
considering that all minisuperspace variables do not commute, so the
symplectic structure was modified. In the classical regime, it is shown that
the anisotropic parameter and the field , for some
value in the cosmological term and noncommutative
parameter, present a dynamical isotropization up to a critical cosmic time
; after this time, the effects of isotropization in the noncommutative
minisuperspace seems to disappear. In the quantum regimen, the probability
density presents a new structure that corresponds to the value of the
noncommutativity parameter.Comment: 17 pages, 6 figures, Acepted in IJT
The Behavior of Kasner Cosmologies with Induced Matter
We extend the induced matter model, previously applied to a variety of
isotropic cases, to a generalization of Bianchi type-I anisotropic cosmologies.
The induced matter model is a 5D Kaluza-Klein approach in which assumptions of
compactness are relaxed for the fifth coordinate, leading to extra geometric
terms. One interpretation of these extra terms is to identify them as an
``induced matter'' contribution to the stress-energy tensor. In similar spirit,
we construct a five dimensional metric in which the spatial slices possess
Bianchi type-I geometry. We find a set of solutions for the five dimensional
Einstein equations, and determine the pressure and density of induced matter.
We comment on the long-term dynamics of the model, showing that the assumption
of positive density leads to the contraction over time of the fifth scale
factor.Comment: 14 page
(Non)commutative isotropization in Bianchi I with Barotropic perfect fluid and Cosmological
We present the classical solutions to the Einstein field equations derived
using the WKB-like and Hamilton procedures. The investigation is carried out in
the commutative and noncommutative scenario for the Bianchi type I cosmological
model coupled to barotropic perfect fluid and Cosmological for two
different gauges. Noncommutativity is achieved by modifying the symplectic
structure considering that all minisuperspace variables does not
commute and by a deformation between all the minisuperspace variables. In the
gauge N=1, it is possible to obtain that the anisotropic parameter tend to a constant curvature for large period of time
considering different values in the noncommutative parameters and
cosmological term. However, this behavior give the idea that is necessary
introduce other class of matter in the models, for to have a real
isotropization in the model, such as dark energy or dark matter.Comment: 15 pages, 1 figur
Impact of transport infrastructure on international competitiveness of Europe
One of the main objectives of the European transport strategy in its 2011 White Paper is to help establish a transport system that enhances competitiveness of European countries. By performing a methodological study, analysing several European transport infrastructure investment cases and conducting a review on various assessment tools, we clarify the relationship between transport infrastructure investment and its wider economic impacts, namely competitiveness and economic growth, we make synthesis of some proposed improvement of the methodology used to assess these impact as well as some recommendations on assessing European Union (EU) policy in transport infrastructure investment in respect of competitiveness and economic growth