Gravitational effects on global hemodynamics in different postures:A closed-loop multiscale mathematical analysis

We present a novel methodology and strategy to predict pressures and flow rates in the global cardiovascular network in different postures varying from supine to upright. A closed-loop, multiscale mathematical model of the entire cardiovascular system (CVS) is developed through an integration of one-dimensional (1D) modeling of the large systemic arteries and veins, and zero-dimensional (0D) lumped-parameter modeling of the heart, the cardiac-pulmonary circulation, the cardiac and venous valves, as well as the microcirculation. A versatile junction model is proposed and incorporated into the 1D model to cope with splitting and/or merging flows across a multibranched junction, which is validated to be capable of estimating both subcritical and supercritical flows while ensuring the mass conservation and total pressure continuity. To model gravitational effects on global hemodynamics during postural change, a robust venous valve model is further established for the 1D venous flows and distributed throughout the entire venous network with consideration of its anatomically realistic numbers and locations. The present integrated model is proven to enable reasonable prediction of pressure and flow rate waveforms associated with cardiopulmonary circulation, systemic circulation in arteries and veins, as well as microcirculation within normal physiological ranges, particularly in mean venous pressures, which well match the in vivo measurements. Applications of the cardiovascular model at different postures demonstrate that gravity exerts remarkable influence on arterial and venous pressures, venous returns and cardiac outputs whereas venous pressures below the heart level show a specific correlation between central venous and hydrostatic pressures in right atrium and veins.

The Gravitational Effects of a Celestial Body with Magnetic Charge and Moment

The gravitational effects (precession of charge-less particles and deflection of light) in the gravitational field of a celestial body with magnetic charge and moment (CM) are investigated. We found that the magnetic charge always weakens the pure Schwarzschild effects, while the magnetic dipole moment deforms the effects in a more complicated way.

Gravitational Effects on Plasma Waves in Environment of Sun and Neutron Star

Local plasma phenomena in environment of Sun are observed closely by spacecrafts in recent years. We provide a new method to apply general relativity to astro-plasma physics in small local area. The relativistic dispersion relations of Langmuir, electromagnetic and cyclotron waves are obtained. The red shifts of Langmuir and cyclotron frequencies are given analytically. A new equilibrium velocity distribution of particles soaked in local gravitational field is suggested. The gravitational effect of a neutron star is also estimated.

Effects of Gravitational Correction on Neutrino Emission from Neutron Stars

Considering the gravitational correction through introduction of weakly interacting light vector U bosons, not only the equation of state （EoS） of the neutron star matter, but also the cooling properties of neutron stars may be changed. In this work, effects of gravitational correction on neutrino emission and cooling of neutron stars in the matter with neutrons, protons, electrons, muons, △- and △0 are studied by the relativistic mean field theory and the related cooling theory. The results show that the effects are sensitive to the ratio of coupling strength to mass squared of U bosons, defined as gu. With increasing gu, the radial region where direct Urca process of nucleons can be allowed in a neutron star with the fixed mass becomes narrower, while the neutrino emissivity is somewhat higher. Moreover, the gravitational correction suppresses the effects of △- on neutrino emission. The gravitational correction leads the star to cool faster, and the higher the gu is, the faster the star cools.

Effects of Homogeneous Plasma on Strong Gravitational Lensing of Kerr Black Holes

Considering the Kerr black hole surrounded by a homogeneous unmagnetized plasma medium, we study the strong gravitational lensing on the equatorial plane of the Kerr black hole. It is found that the presence of the uniform plasma can increase the photon-sphere radius r_{／rm ps}, the coefficients ／bar{a} and ／bar{b}, the angular position of the relativistic images （／theta_{／infty}）, the deflection angle ／alpha（／theta） and the angular separation s. However, the relative magnitude r_{／rm m} decreases in the presence of the uniform plasma medium. It is also shown that the impact of the uniform plasma on the effect of strong gravitational lensing becomes smaller as the spin of the Kerr black hole increases in the prograde orbit （a〉0）. In particular, for the extreme black hole （a=0.5）, the effect of strong gravitational lensing in the homogeneous plasma medium is the same as the case in vacuum for the prograde orbit.

Gravitational Shielding Effect in Gauge Theory of Gravity

In 1992,E.E.Podkletnov and R.Nieminen found that under certain conditions,ceramic superconductor with composite structure reveals weak shielding properties against gravitational force.In classical Newton's theory of gravity and even in Einstein's general theory of gravity,there are no grounds of gravitational shielding effects.But in quantum gauge theory of gravity,the gravitational shielding effects can be explained in a simple and natural way.In quantum gauge theory of gravity,gravitational gauge interactions of complex scalar field can be formulated based on gauge principle.After spontaneous symmetry breaking,if the vacuum of the complex scalar field is not stable and uniform,there will be a mass term of gravitational gauge field.When gravitational gauge field propagates in this unstable vacuum of the complex scalar field,it will decays exponentially,which is the nature of gravitational shielding effects.The mechanism of gravitational shielding effects is studied in this paper,and some main properties of gravitational shielding effects are discussed.

Repulsive effects in steady axisymmetric fields

In this paper the repulsive effects in the Kerr and Kerr-Newman fields are discussed. The contributions made by all parameters of the fields and test particles to the repulsive effects are also discussed, and the accretive effect on interstellar dust, i.e. the distribution of dust is calculated. The discussion is also carried out on the slow rotation of the Kerr field in which the effect is related to the positions and velocities of the particles and the orientations of their trajectories as well.

Gravitational effect of water circulation in the northwest Yunnan

Water circulation is the main disturbance source against precise gravimetry measurement which is one of the principal means of geodynamic study. Some scientists studied the disturbance of water level changes in lakes andrivers and groundwater activities on gravity field.Taking water circulation as a whole and combining it with thehydrogeological conditions in northwest Yunnan mountainous area and the measured gravity data,this paperstudies the features, connections of water circulation in atmosphere,on surface and under ground and its effecton gravimetric data. The main conclusions are as follows: 1) The water circulation in atmosphere has little directdisturbance on gravity field 1 2 ) The change of lake water level may cause gravitational effect of (10- 20) × 10-8m. s-2 ; 3) In the NW Yunnan, types of the groundwater are various,and its changes are complicated, it isnecessary to study point by point. In general, its disturbance on gravity field in this region is about 10 × 10- 8m. s- 2, less than that in plain area.

The Nature of Space and of Gravitation

Many recent highly precise and unmistakable observational facts achieved thanks to the tightly synchronized clocks of the GPS, provide consistent evidence that the gravitational fields are created by velocity fields of real space itself, a vigorous and very stable quantum fluid like spatial medium, the same space that rules the propagation of light and the inertial motion of matter. It is shown that motion of this real space in the ordinary three dimensions round the Earth, round the Sun and round the galactic centers throughout the universe, according to velocity fields closely consistent with the local main astronomical motions, correctly induces the gravitational dynamics observed within these gravitational fields. In this spacedynamics the astronomical bodies all closely rest with respect to the real space, which forth-rightly leads to the observed null results of the Michelson light anisotropy experiments as well as to the absence of effects of the solar and galactic gravitational fields on the rate of clocks moving with Earth as recently discovered with the help of the GPS clocks. This spacedynamics exempts us from explaining the circular orbital motions of the planets round the Sun, likewise the rotation of Earth exempted people from explaining the diurnal transit of the heavens in the days of Copernicus and Galileo, because it is space itself that so moves. This spacedynamics also eliminates the need of dark matter and dark energy to explain respectively the galactic gravitational dynamics and the accelerated expansion of the universe. It also straightforwardly accounts in terms of well known and genuine physical effects for all the other observed effects, caused by the gravitational fields on the velocity of light and on the rate of clocks, including all the new effects recently discovered with the help of the GPS. It moreover simulates the non-Euclidean metric underlying Einstein’s spacetime curvature. This spacedynamics is the crucial innovation in the current world conception that definitively resolves all at once the troubles afflicting the current theories of space and gravitation.

A Godunov-Type Solver for the Numerical Approximation of Gravitational Flows

We present a new numerical method to approximate the solutions of an Euler-Poisson model,which is inherent to astrophysical flows where gravity plays an important role.We propose a discretization of gravity which ensures adequate coupling of the Poisson and Euler equations,paying particular attention to the gravity source term involved in the latter equations.In order to approximate this source term,its discretization is introduced into the approximate Riemann solver used for the Euler equations.A relaxation scheme is involved and its robustness is established.The method has been implemented in the software HERACLES[29]and several numerical experiments involving gravitational flows for astrophysics highlight the scheme.

Repulsive gravitational effect of a quantum wave packet and experimental scheme with superfluid helium

We consider the gravitational effect of quantum wave packets when quantum mechanics, gravity, and thermodynamics are simultaneously considered. Under the assumption of a thermodynamic origin of gravity, we propose a general equation to describe the gravitational effect of quantum wave packets. In the classical limit, this equation agrees with Newton＇s law of gravitation. For quantum wave packets, however, it predicts a repulsive gravitational effect. We propose an experimental scheme using superfluid helium to test this repulsive gravitational effect. Our studies show that, with present technology such as superconducting gravimetry and gravitational effect for superfluid helium are within cold atom interferometry, tests of the repulsive experimental reach.

Numerical Simulation of Compositional Flow in Porous Media under Gravity

This paper is concerned with the numerical simulation of multiphase,multi-component flow in porous media.The model equations are based on compositional flow with mass interchange between phases.The compositional model consists of Darcy’s law for volumetric flow velocities,mass conservation for hydrocarbon components,ther-modynamic equilibrium for mass interchange between phases,and an equation of state for saturations.High-accurate finite volume methods on unstructured grids are used to discretize the model governing equations.Special emphasis is placed on studying the influence of gravitational effects on the overall displacement dynamics.In particular,free and forced convections,diffusions,and dispersions are studied in separate and com-bined cases,and their interplays are intensively analyzed for gravitational instabilities.Extensive numerical experiments are presented to validate the numerical study under consideration.