نتایج جستجو برای: gravity field

تعداد نتایج: 837945  

, حسین غفارنژاد, ,

Pauli (or Einstein) frame is used to study the Brans-Dicke gravity theory, minimally coupled with dilatonic Brans-Dicke scalar field, whose solutions involve degenerate metrics. Some of these solutions exhibit transitions from an Euclidean domain to a Lorentzian space-time corresponding to a spatially flat Robertson-Walker cosmology.

2003
D. Grumiller W. Kummer

The application of quantum theory to gravity is beset with many technical and conceptual problems. After a short tour d’horizon of recent attempts to master those problems by the introduction of new approaches, we show that the aim, a background independent quantum theory of gravity, can be reached in a particular area, 2d dilaton quantum gravity, without any assumptions beyond standard quantum...

2012
Sarah Folkerts Daniel F. Litim Jan M. Pawlowski

We study the behaviour of Yang-Mills theory under the inclusion of gravity. In the weakgravity limit, the running gauge coupling receives no contribution from the gravitational sector, if all symmetries are preserved. This holds true with and without cosmological constant. We also show that asymptotic freedom persists in general field-theory-based gravity scenarios including gravitational shiel...

2008
P. M. Saffin

We consider the effect that gravity has when one tries to set up a constant background form field. We find that in analogy with the Melvin solution, where magnetic field lines self-gravitate to form a flux-tube, the self-gravity of the form field creates fluxbranes. Several exact solutions are found corresponding to different transverse spaces and world-volumes, a dilaton coupling is also consi...

2005
D. Deeg

We investigate brane world models in higher-derivative gravity theories where the gravitational Lagrangian is an arbitrary function of the Ricci scalar. Making use of the conformal equivalence of such gravity models and Einstein-Hilbert gravity with a scalar field, we deduce the main features of higher-derivative gravity brane worlds. We solve for a gravity model that has corrections quadratic ...

Journal: :Applied Mathematics and Computation 2011
A. M. Abd-Alla S. R. Mahmoud S. M. Abo-Dahab M. I. Helmy

Keywords: Incompressible Initial stress Anisotropic S-wave Gravity field a b s t r a c t In this paper, propagation of shear waves in a non-homogeneous anisotropic incompress-ible, gravity field and initially stressed medium is studied. Analytical analysis reveals that the velocity of propagation of the shear waves depends upon the direction of propagation, the anisotropy, gravity field, non-ho...

Journal: :The Physiologist 1993
R W Ballard P Davies C A Fuller

Data from spaceflight and ground based experiments have clearly demonstrated the importance of Earth gravity for normal physiological function in man and animals. Gravitational Physiology is concerned with the role and influence of gravity on physiological systems. Research in this field examines how we perceive and respond to gravity and the mechanisms underlying these responses. Inherent in o...

2006
João B. C. Silva Valéria C. F. Barbosa

We have developed a new approach for estimating the location and geometry of several density anomalies that give rise to a complex, interfering gravity field. The user interactively defines the assumed outline of the true gravity sources in terms of points and line segments, and the method estimates sources closest to the specified outline to achieve a match between the predicted and observed g...

2015
Marco Hernandez Tian Ma Shouhong Wang

In (T. Ma and S. Wang. Gravitational field equations and theory of dark matter and dark energy, Discrete and Continuous Dynamical Systems, Ser. A, 34(2): 335–366, 2014; arXiv:1206.5078v2), a new set of gravitational field equations are derived based only on 1) the Einstein principle of general relativity, and 2) the principle of interaction dynamics, due to the the presence of dark energy and d...

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