We study a model with decay of dark energy and creation of the dark matter particles. We integrate the field equations and find the transition redshift where the evolution process of the universe change the accelerated expansion, and discuss the luminosity distance, acoustic oscillations and the statefinder parameters.

We study a model with decay of dark energy and creation of the dark matter particles. We integrate the field equations and find the transition redshift where the evolution process of the universe change from decelerated to an accelerated phase expansion, and briefly discuss the transition epoch and the broken of the strong energy condition. Finally, we examine the growing of the inhomogeneities.

Using a gauge-invariant formalism we find the density contrast equation in a cosmological scenario with particle production at the expenses of the gravitational field (open system cosmology). First, we find the modes for the density contrast considering that the particle production process participate of the inhomogeneities formation, and in a second phase the creation process mimics the inclusion of the a smooth L term , in the sense that it is not affects small deviations from homogeneity. The cosmic background has an accelerated regime, where an additional pressure due to the creation process is responsible for the cosmic acceleration. We study in this work if the creation process of particles in the cosmic fluid contributes to the inhomogeneities formation in an accelerated universe.

Fazemos uma breve análise da hierarquia de objetivos educacionais no domínio cognitivo seguindo a taxonomia sugerida por Bloom. Por outro lado, usamos a computação algébrica para construir as figuras de Lissajous e as comparamos com as já existentes na literatura. Classificamos a comparação das figuras obtidas com as já existentes como um processo ao terceiro nível da taxonomia de Bloom, o de aplicação.

We make a brief analysis of the hierarchy of the educational objectives following the Bloom taxonomy. On other hand, we use algebric computation to obtain the Lissajous figures and compare our results with those from the literature. We classify the comparation of our results with the figures in the literature as the application level in the Bloom's taxonomy.

A new equation for the density contrast is derived in the framework of reexamined Newtonian cosmology if we take into account adiabatic matter creation in the universe. The age of the universe and the reach of non linear regime of the density contrast are usually treated separately in the literature and this may leadtocontroversial conclusions regarding the most adequate scenario to describe the universe. We relate the age of the universe and the growing mode of the density contrast by introducing a variable x that relates both of them, so that both aspects are treated simultaneously. We apply this procedure to the Friedmann type model where the source of particle production is Y = 3nbH.