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- J A S Lima, M Mohazzab
- 1996

It is argued that the full Einstien equation has more information than the space component of Einstien equation plus energy conservation equation. Applying the former approach to the D-dimensional decrumpling FRW cosmology leads to a diierent result which suuers from a singularity together with lacking the turning points.

- J. A. S. Lima
- 1996

SUMMARY A new Planckian distribution for cosmologies with photon creation is derived using thermodynamics and semiclassical considerations. This spectrum is preserved during the evolution of the universe and compatible with the present spectral shape of the cosmic microwave background radiation(CMBR). Accordingly, the widely spread feeling that cosmologies… (More)

- J A Lima, R Silva, A R Plastino
- Physical review letters
- 2001

The kinetic foundations of Tsallis' nonextensive thermostatistics are investigated through Boltzmann's transport equation approach. Our analysis follows from a nonextensive generalization of the "molecular chaos hypothesis." For q>0, the q-transport equation satisfies an H theorem based on Tsallis entropy. It is also proved that the collisional equilibrium… (More)

- J. A. S. Lima
- 1996

The thermodynamic behavior of vacuum decaying cosmologies is investigated within a manifestly covariant formulation. Such a process corresponds to a continuous irreversible energy flow from the vacuum component to the created matter constituents. It is shown that if the specific entropy per particle remains constant during the process, the equilibrium… (More)

- J. A. S. Lima, A. S. M. Germano, R. W. Abramo
- 1996

Some properties of cosmological models with matter creation are investigated in the framework of the Friedman-Robertson-Walker (FRW) line element. For adiabatic matter creation, as developed by Prigogine and coworkers, we derive a simple expression relating the particle number density n and energy density ρ which holds regardless of the matter creation… (More)

- J A S Lima, M Trodden
- 1995

We consider a nonsingular deflationary cosmological model with decaying vacuum energy density in universes of arbitrary spatial curvature. Irrespective of the value of k, the models are characterized by an arbitrary time scale H −1 I which determines the initial temperature of the universe and the largest value of the vacuum energy density, the slow decay… (More)

The flat inflationary dust universe with matter creation proposed by Prigogine and coworkers is generalized and its dynamical properties are reexamined. It is shown that the starting point of these models depends critically on a dimensionless parameter Σ, closely related to the matter creation rate ψ. For Σ bigger or smaller than unity flat universes can… (More)

- J S Alcaniz, J A S Lima
- 1999

The ages of two old galaxies (53W091, 53W069) at high redshifts are used to constrain the value of the cosmological constant in a flat universe (ΛCDM) and the density parameter Ω M in Friedmann-Robertson-Walker (FRW) models with no Λ-term. In the case of ΛCDM models, the quoted galaxies yield two lower limits for the vacuum energy density parameter, Ω Λ ≥… (More)

- Alexandre Felipe, Guilherme Espíndola, Hypolito J Kalinowski, José A S Lima, Aleksander S Paterno
- Optics express
- 2012

This work reports a modified flame-brush technique to fabricate fiber tapers with arbitrary waist profiles. The flame-brush approach is used to produce small step reductions in the fiber diameter, or step-tapers, with a constant speed flame brush sweep, while the fiber is uniformly stretched. Arbitrary waist profiles in tapers are fabricated by… (More)

Predictions about the kinematic expansion history of the universe are investigated by using the 307 supernovae type Ia from the Union Compilation set. Three simple model parameterizations for the deceleration parameter (constant, linear and abrupt transition) and two different models that are explicitly parametrized by a jerk parameter (constant and… (More)