Type I, II, and III spatially homogeneous cosmologies with electromagnetic field

1980 ◽  
Vol 235 ◽  
pp. 307 ◽  
Author(s):  
K. A. Dunn ◽  
B. O. J. Tupper
Keyword(s):  
Electromagnetic Field ◽  
Type I ◽  
Spatially Homogeneous ◽  
Homogeneous Cosmologies

Electromagnetic fields enhance chondrogenesis of human adipose-derived stem cells in a chondrogenic microenvironment in vitro

2013 ◽  
Vol 114 (5) ◽  
pp. 647-655 ◽  
Author(s):  
Chung-Hwan Chen ◽  
Yi-Shan Lin ◽  
Yin-Chih Fu ◽  
Chih-Kuang Wang ◽  
Shun-Cheng Wu ◽  
...  
Keyword(s):  
Stem Cells ◽  
Electromagnetic Field ◽  
Cell Viability ◽  
Chondrogenic Differentiation ◽  
Collagen Type ◽  
Cartilage Tissue ◽  
Pulse Electromagnetic Field ◽  
Type I ◽  
Adipose Derived Stem Cells ◽  
Pemf Treatment

We tested the hypothesis that electromagnetic field (EMF) stimulation enhances chondrogenesis in human adipose-derived stem cells (ADSCs) in a chondrogenic microenvironment. A two-dimensional hyaluronan (HA)-coated well (2D-HA) and a three-dimensional pellet culture system (3D-pellet) were used as chondrogenic microenvironments. The ADSCs were cultured in 2D-HA or 3D-pellet, and then treated with clinical-use pulse electromagnetic field (PEMF) or the innovative single-pulse electromagnetic field (SPEMF) stimulation. The cytotoxicity, cell viability, and chondrogenic and osteogenic differentiations were analyzed after PEMF or SPEMF treatment. The modules of PEMF and SPEMF stimulations used in this study did not cause cytotoxicity or alter cell viability in ADSCs. Both PEMF and SPEMF enhanced the chondrogenic gene expression (SOX-9, collagen type II, and aggrecan) of ADSCs cultured in 2D-HA and 3D-pellet. The expressions of bone matrix genes (osteocalcin and collagen type I) of ADSCs were not changed after SPEMF treatment in 2D-HA and 3D-pellet; however, they were enhanced by PEMF treatment. Both PEMF and SPEMF increased the cartilaginous matrix (sulfated glycosaminoglycan) deposition of ADSCs. However, PEMF treatment also increased mineralization of ADSCs, but SPEMF treatment did not. Both PEMF and SPEMF enhanced chondrogenic differentiation of ADSCs cultured in a chondrogenic microenvironment. SPEMF treatment enhanced ADSC chondrogenesis, but not osteogenesis, when the cells were cultured in a chondrogenic microenvironment. However, PEMF enhanced both osteogenesis and chondrogenesis under the same conditions. Thus the combination of a chondrogenic microenvironment with SPEMF stimulation can promote chondrogenic differentiation of ADSCs and may be applicable to articular cartilage tissue engineering.

A spatially homogeneous gravitational field

1966 ◽  
Vol 62 (1) ◽  
pp. 87-89 ◽  
Author(s):  
V. Joseph
Keyword(s):  
Gravitational Field ◽  
Canonical Form ◽  
Riemann Tensor ◽  
Vacuum Field ◽  
Type I ◽  
Field Equations ◽  
Parameter Group ◽  
Spatially Homogeneous ◽  
Homogeneous Gravitational Field ◽  
Type V

AbstractA solution of Einstein's vacuum field equations, apparently new, is exhibited. The metric, which is homogeneous (that is, admits a three-parameter group of motions transitive on space-like hypersurfaces), belongs to Taub Type V. The canonical form of the Riemann tensor, which is of Petrov Type I, is determined.

scholarly journals Two Bianchi type VIII spatially homogeneous cosmologies

1977 ◽  
Vol 52 (1) ◽  
pp. 1-10 ◽  
Author(s):  
J. G. Miller
Keyword(s):  
Bianchi Type ◽  
Type Viii ◽  
Spatially Homogeneous ◽  
Homogeneous Cosmologies

scholarly journals Interaction of Bianchi type-I anisotropic cloud string cosmological model universe with electromagnetic field

2020 ◽  
Vol 17 (09) ◽  
pp. 2050133
Author(s):  
Kangujam Priyokumar Singh ◽  
Mahbubur Rahman Mollah ◽  
Rajshekhar Roy Baruah ◽  
Meher Daimary
Keyword(s):  
Electromagnetic Field ◽  
Cosmological Model ◽  
Bianchi Type ◽  
Physical Parameters ◽  
Type I ◽  
Field Equations ◽  
Rest Energy ◽  
Model Universe ◽  
Bianchi Type I ◽  
String Cosmological Model

Here, we have investigated the interaction of Bianchi type-I anisotropic cloud string cosmological model universe with electromagnetic field in the context of general relativity. In this paper, the energy-momentum tensor is assumed to be the sum of the rest energy density and string tension density with an electromagnetic field. To obtain exact solution of Einstein’s field equations, we take the average scale factor as an integrating function of time. Also, the dynamics and significance of various physical parameters of model are discussed.

Exact spatially homogeneous cosmologies

1980 ◽  
Vol 12 (10) ◽  
pp. 805-823 ◽  
Author(s):  
C. B. Collins ◽  
E. N. Glass ◽  
D. A. Wilkinson
Keyword(s):  
Spatially Homogeneous ◽  
Homogeneous Cosmologies

scholarly journals LRS Bianchi type-I cosmological model with constant deceleration parameter in f(R,T) gravity

2017 ◽  
Vol 14 (11) ◽  
pp. 1750158 ◽  
Author(s):  
Binaya K. Bishi ◽  
S. K. J. Pacif ◽  
P. K. Sahoo ◽  
G. P. Singh
Keyword(s):  
Cosmological Model ◽  
Deceleration Parameter ◽  
Hubble Parameter ◽  
Bianchi Type ◽  
Specific Model ◽  
Type I ◽  
Hubble’S Parameter ◽  
Constant Deceleration Parameter ◽  
Bianchi Type I ◽  
Spatially Homogeneous

A spatially homogeneous anisotropic LRS Bianchi type-I cosmological model is studied in [Formula: see text] gravity with a special form of Hubble's parameter, which leads to constant deceleration parameter. The parameters involved in the considered form of Hubble parameter can be tuned to match, our models with the [Formula: see text]CDM model. With the present observed value of the deceleration parameter, we have discussed physical and kinematical properties of a specific model. Moreover, we have discussed the cosmological distances for our model.

Power law singularities in orthogonal spatially homogeneous cosmologies

1984 ◽  
Vol 16 (7) ◽  
pp. 657-674 ◽  
Author(s):  
J. Wainwright
Keyword(s):  
Power Law ◽  
Spatially Homogeneous ◽  
Homogeneous Cosmologies

scholarly journals Some geometrical aspects of Bianchi type-I space time

2002 ◽  
pp. 79-86
Author(s):  
G. Mohanty ◽  
R.C. Sahu ◽  
P.K. Sahoo
Keyword(s):  
Bianchi Type ◽  
Space Time ◽  
Type I ◽  
Einstein Theory ◽  
Bianchi Type I ◽  
Spatially Homogeneous

A problem of spatially homogeneous Bianchi type-I space-time is investigated in Einstein theory without source of gravitation. Some geometrical natures of the space-time are discussed.

On a Bianchi type-I space-time with bulk viscosity in f(R,T) gravity

2021 ◽  
Author(s):  
M. Koussour ◽  
M. Bennai
Keyword(s):  
Deceleration Parameter ◽  
Bianchi Type ◽  
Momentum Tensor ◽  
Energy Conditions ◽  
Type I ◽  
Field Equations ◽  
Bulk Fluid ◽  
Bianchi Type I ◽  
Deceleration Phase ◽  
Spatially Homogeneous

In this paper, we present a spatially homogeneous and anisotropic Bianchi type-I cosmological model with a viscous bulk fluid in [Formula: see text] gravity where [Formula: see text] and [Formula: see text] are the Ricci scalar and trace of the energy-momentum tensor, respectively. The field equations are solved explicitly using the hybrid law of the scale factor, which is related to the average Hubble parameter and gives a time-varying deceleration parameter (DP). We found the deceleration parameter describing two phases in the universe, the early deceleration phase [Formula: see text] and the current acceleration phase [Formula: see text]. We have calculated some physical and geometric properties and their graphs, whether in terms of time or redshift. Note that for our model, the bulk viscous pressure [Formula: see text] is negative and the energy density [Formula: see text] is positive. The energy conditions and the [Formula: see text] analysis for our spatially homogeneous and anisotropic Bianchi type-I model are also discussed.

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