scholarly journals Plane symmetric self-gravitating fluids with pressure equal to energy density

1973 ◽  
Vol 29 (1) ◽  
pp. 61-77 ◽  
Author(s):  
Romualdo Tabensky ◽  
A. H. Taub
Keyword(s):  
Energy Density ◽  
Plane Symmetric

scholarly journals f(T) gravity and energy distribution in Landau–Lifshitz prescription

2018 ◽  
Vol 27 (04) ◽  
pp. 1850039 ◽  
Author(s):  
M. G. Ganiou ◽  
M. J. S. Houndjo ◽  
J. Tossa
Keyword(s):  
General Relativity ◽  
Energy Density ◽  
Energy Distribution ◽  
Cosmic String ◽  
Mass Formula ◽  
Plane Symmetric ◽  
Symmetric Metrics ◽  
Teleparallel Theory ◽  
Momentum Complex ◽  
Theory View

We investigate in this paper the Landau–Lifshitz energy distribution in the framework of [Formula: see text] theory view as a modified version of Teleparallel theory. From some important Teleparallel theory results on the localization of energy, our investigations generalize the Landau–Lifshitz prescription from the computation of the energy–momentum complex to the framework of [Formula: see text] gravity as it is done in the modified versions of General Relativity. We compute the energy density in the first step for three plane-symmetric metrics in vacuum. We find for the second metric that the energy density vanishes independently of [Formula: see text] models. We find that the Teleparallel Landau–Lifshitz energy–momentum complex formulations for these metrics are different from those obtained in General Relativity for the same metrics. Second, the calculations are performed for the cosmic string spacetime metric. It results that the energy distribution depends on the mass [Formula: see text] and the radius [Formula: see text] of cosmic string and it is strongly affected by the parameter of the considered quadratic and cubic [Formula: see text] models. Our investigation with this metric induces interesting results susceptible to be tested with some astrophysics hypothesis.

Cosmological solution with matter in a new theory of gravitation

1980 ◽  
Vol 58 (6) ◽  
pp. 729-736 ◽  
Author(s):  
G. Kunstatter ◽  
J. W. Moffat ◽  
P. Savaria
Keyword(s):  
Energy Density ◽  
Lower Bound ◽  
Initial Temperature ◽  
Cosmological Solution ◽  
Homogeneous Solution ◽  
Helium Abundance ◽  
Hermitian Metric ◽  
Plane Symmetric ◽  
Curvature Energy ◽  
Theory Of Gravitation

We present a plane-symmetric, homogeneous solution with matter in a theory of gravitation based on a non-symmetric Hermitian metric. The solution describes a universe which begins with finite 4-curvature, energy density, and temperature. The initial temperature [Formula: see text] depends on a new parameter κ in the theory. An analysis of primordial helium abundance gives rise to a lower bound [Formula: see text]. The resulting cosmology is consistent with all presently known observations.

STATIC PLANE SYMMETRIC INTERIOR SOLUTIONS IN f(R) GRAVITY

2013 ◽  
Vol 28 (10) ◽  
pp. 1350041 ◽  
Author(s):  
M. SHARIF ◽  
ZURIAT ZAHRA
Keyword(s):  
Energy Density ◽  
Perfect Fluid ◽  
Ricci Scalar ◽  
Plane Symmetric ◽  
Static Plane ◽  
Interior Solutions

This paper is devoted to explore static plane symmetric solutions in metric f(R) gravity with matter as a perfect fluid. We obtain seven types of solutions. The energy density, pressure and the Ricci scalar are evaluated for each solution. Finally, we find four such solutions which satisfy the required conditions of physically acceptable solutions out of which two are singular and two nonsingular.

Electromagnetic effects on the inhomogeneity of planar symmetry

2014 ◽  
Vol 29 (26) ◽  
pp. 1450129 ◽  
Author(s):  
M. Sharif ◽  
M. Zaeem Ul Haq Bhatti
Keyword(s):  
Energy Density ◽  
Evolution Equations ◽  
Anisotropic Pressure ◽  
Plane Symmetric ◽  
Anisotropic Matter ◽  
Maxwell Field Equation ◽  
Dissipative Case ◽  
Energy Density Inhomogeneity ◽  
Planar Symmetry ◽  
Inhomogeneity Factor

In this work, we aim to identify the effects of electromagnetic field on the energy density inhomogeneity in self-gravitating plane symmetric spacetime filled with imperfect matter in terms of dissipation and anisotropic pressure. We formulate the Einstein–Maxwell field equation, conservation laws, evolution equations for the Weyl tensor and the transport equation for diffusion approximation. Inhomogeneity factors are identified for some particular cases of non-dissipative and dissipative fluids. For non-dissipative case, we analyze the inhomogeneity factor for dust, isotropic and anisotropic matter distributions while dissipative matter distribution includes the inhomogeneity factor only for geodesic dust fluid. We conclude that electric charge increases the inhomogeneity in the energy density which is due to shear, anisotropy and dissipation.

Fine-scale taxonomic and temporal variability in the energy density of invertebrate prey of juvenile Chinook salmon Oncorhynchus tshawytscha

2020 ◽  
Vol 655 ◽  
pp. 185-198
Author(s):  
J Weil ◽  
WDP Duguid ◽  
F Juanes
Keyword(s):  
Energy Density ◽  
Chinook Salmon ◽  
Temporal Variability ◽  
Energy Content ◽  
Single Point ◽  
Single Species ◽  
Fine Scale ◽  
Temporal Differences ◽  
Juvenile Chinook Salmon ◽  
Juvenile Chinook

Variation in the energy content of prey can drive the diet choice, growth and ultimate survival of consumers. In Pacific salmon species, obtaining sufficient energy for rapid growth during early marine residence is hypothesized to reduce the risk of size-selective mortality. In order to determine the energetic benefit of feeding choices for individuals, accurate estimates of energy density (ED) across prey groups are required. Frequently, a single species is assumed to be representative of a larger taxonomic group or related species. Further, single-point estimates are often assumed to be representative of a group across seasons, despite temporal variability. To test the validity of these practices, we sampled zooplankton prey of juvenile Chinook salmon to investigate fine-scale taxonomic and temporal differences in ED. Using a recently developed model to estimate the ED of organisms using percent ash-free dry weight, we compared energy content of several groups that are typically grouped together in growth studies. Decapod megalopae were more energy rich than zoeae and showed family-level variability in ED. Amphipods showed significant species-level variability in ED. Temporal differences were observed, but patterns were not consistent among groups. Bioenergetic model simulations showed that growth rate of juvenile Chinook salmon was almost identical when prey ED values were calculated on a fine scale or on a taxon-averaged coarse scale. However, single-species representative calculations of prey ED yielded highly variable output in growth depending on the representative species used. These results suggest that the latter approach may yield significantly biased results.

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