Negative energy standing wave instability in the presence of flow

2018 ◽  
Vol 84 (1) ◽  
Author(s):  
Michael S. Ruderman
Keyword(s):  
Standing Wave ◽  
Negative Energy ◽  
Flow Speed ◽  
Tangential Discontinuity ◽  
Positive Energy ◽  
Wave Instability ◽  
Long Wavelength ◽  
Backward Wave ◽  
Moving Plasma ◽  
The Difference

We study standing waves on the surface of a tangential discontinuity in an incompressible plasma. The plasma is moving with constant velocity at one side of the discontinuity, while it is at rest at the other side. The moving plasma is ideal and the plasma at rest is viscous. We only consider the long wavelength limit where the viscous Reynolds number is large. A standing wave is a superposition of a forward and a backward wave. When the flow speed is between the critical speed and the Kelvin–Helmholtz threshold the backward wave is a negative energy wave, while the forward wave is always a positive energy wave. We show that viscosity causes the standing wave to grow. Its increment is equal to the difference between the negative energy wave increment and the positive energy wave decrement.

scholarly journals Rearing diet effects on body condition and milk performance in first lactating dairy cows – A longitudinal study

2005 ◽  
Vol 48 (5) ◽  
pp. 417-427 ◽  
Author(s):  
U. Müller ◽  
A. R. Sharifi ◽  
R. Staufenbiel ◽  
L. Hasselmann ◽  
R. Tripmacher ◽  
...  
Keyword(s):  
Energy Balance ◽  
Negative Energy ◽  
Positive Energy ◽  
Feeding Intensity ◽  
Positive Energy Balance ◽  
Milk Performance ◽  
Fat Thickness ◽  
The Difference ◽  
Feeding Effects ◽  
Daily Milk Yield

Abstract. Fourteen pairs of identical female Holstein twins were used for a feeding trial during a period between 3rd and 21st month. One in two sibling was reared continuously at a medium (M) and the other one at a high (H) feeding intensity. Lasting diet effects of body weight (BW), back fat thickness (BFT), and milk performance (M-kg) were analyzed for the subsequent lactation. A lasting diet effect was verifiable for BFT, whereas BW don’t differ between groups. BFT indicated the changes from negative to positive energy balance 7 and 10 weeks later than BW, for M and H group, respectively. Besides, BFT showed, that the duration and dimension of negative energy balance was longer in H group than in M group. BFT difference became smaller according day of lactation and resulted in about zero at day 305 of lactation. If the groups were compared only by feeding intensity, the daily milk yield was 1.7 kg higher in M than in H group, but the difference didn’t show any significance (p=0.22). However, the tendency of superiority was completely absorbed after the addition of the covariate age at first calving (AFC) in the model. Presented date in identical twins give no indications for lasting feeding effects per se on milk performance.

scholarly journals The birth of the universe in a new G-theory approach

2017 ◽  
Vol 32 (05) ◽  
pp. 1750033 ◽  
Author(s):  
Alireza Sepehri ◽  
Richard Pincak
Keyword(s):  
Degrees Of Freedom ◽  
Boundary Surface ◽  
Negative Energy ◽  
Positive Energy ◽  
Theory Approach ◽  
Superstring Theory ◽  
Extra Energy ◽  
Extended Theories Of Gravity ◽  
The Difference ◽  
M Theory

Recently, Padmanabhan has discussed that the expansion of the cosmic space is due to the difference between the number of degrees of freedom on the boundary surface and the number of degrees of freedom in a bulk region. Now, a natural question arises that how these degrees of freedom emerged from nothing? We try to address this issue in a new theory which is more complete than M-theory and reduces to it with some limitations. In M-theory, there is no stable object like stable M3-branes that our universe is formed on it and for this reason cannot help us to explain cosmological events. In this research, we propose a new theory, named G-theory which could be the mother of M-theory and superstring theory. In G-theory, at the beginning, two types of G0-branes, one with positive energy and one with negative energy are produced from nothing in 14 dimensions. Then, these branes are compactified on three circles via two different ways (symmetrically and anti-symmetrically), and two bosonic and fermionic parts of action for M0-branes are produced. By joining M0-branes, supersymmetric Mp-branes are created which contain the equal number of degrees of freedom for fermions and bosons. Our universe is constructed on one of Mp-branes and other Mp-brane and extra energy play the role of bulk. By dissolving extra energy which is produced by compacting actions of Gp-branes, into our universe, the number of degrees of freedom on it and also its scale factor increase and universe expands. We test G-theory with observations and find that the magnitude of the slow-roll parameters and the tensor-to-scalar ratio in this model are very much smaller than one which are in agreement with predictions of experimental data. Finally, we consider the origin of the extended theories of gravity in G-theory and show that these theories could be anomaly free.

scholarly journals The scattering of positrons by electrons with exchange on Dirac’s theory of the positron

1936 ◽  
Vol 154 (881) ◽  
pp. 195-206 ◽  
Keyword(s):  
Relative Velocity ◽  
Collision Cross Section ◽  
Energy State ◽  
Negative Energy ◽  
Positive Energy ◽  
Exchange Effect ◽  
Relativistic Case ◽  
Conservation Of Energy ◽  
The Difference ◽  
Energy And Momentum

It has been shown by Mott that exchange effects play a considerable part in the collision and consequent scattering of one electron by another. Mott’s original calculation was non-relativistic, and there the exchange effect vanishes when the two electrons have their spins pointing in opposite directions. Møller later developed relativistically invariant expressions for the collision of two charged particles with spin, and it may be seen directly from Møller’s general formula for the collision cross-section that, in the collision of two identical particles, the effect of exchange does not in general vanish even when the two colliding particles initially have their spins pointing in opposite directions. It tends however to zero in this case as the relative velocity of the particles becomes small compared to c , the velocity of light, in agreement with the calculation of Mott. The effect of exchange in the general relativistic case will still be considerable if one of the two electrons be initially (and therefore finally) in a state of negative energy. (If one of the electrons be initially in a negative energy state, then it follows from the conservation of energy and momentum that one of them must be finally in a state of negative energy.) This at once leads to the conclusion that in the collision of an electron with a positron, the calculation of this process on the Dirac theory of the positron, where the positron is considered as an unoccupied state of negative energy, would lead to a result different from that which we should get if we did the calculation considering the positron as an independent positively charged particle in a state of positive energy whose behaviour is descibed by the Dirac equation. The difference would be due to the effect of exchange between the electron we observe initially and the virtual electrons in states of negative energy. As we shall show, the effect of this exchange is considerable. It tends to zero, however, when the relative velocity of the electron and positron becomes small compared to c , as we should expect from what has been said in the last paragraph.

Dissipative instability of the MHD tangential discontinuity in magnetized plasmas with anisotropic viscosity and thermal conductivity

1996 ◽  
Vol 56 (2) ◽  
pp. 285-306 ◽  
Author(s):  
M. S. Ruderman ◽  
E. Verwichte ◽  
R. Erdélyi ◽  
M. Goossens
Keyword(s):  
Thermal Conductivity ◽  
Dispersion Equation ◽  
Viscosity Coefficient ◽  
Tangential Discontinuity ◽  
Stability Criteria ◽  
Threshold Velocity ◽  
Cold Plasmas ◽  
The Difference ◽  
The Stability ◽  
Anisotropic Viscosity

The stability of the MHD tangential discontinuity is studied in compressible plasmas in the presence of anisotropic viscosity and thermal conductivity. The general dispersion equation is derived, and solutions to this dispersion equation and stability criteria are obtained for the limiting cases of incompressible and cold plasmas. In these two limiting cases the effect of thermal conductivity vanishes, and the solutions are only influenced by viscosity. The stability criteria for viscous plasmas are compared with those for ideal plasmas, where stability is determined by the Kelvin—Helmholtz velocity VKH as a threshold for the difference in the equilibrium velocities. Viscosity turns out to have a destabilizing influence when the viscosity coefficient takes different values at the two sides of the discontinuity. Viscosity lowers the threshold velocity V below the ideal Kelvin—Helmholtz velocity VKH, so that there is a range of velocities between V and VKH where the overstability is of a dissipative nature.

Pneumatic Mechanism of Gas Cooled or Heated Through a Throttle Orifice

2011 ◽  
Vol 141 ◽  
pp. 408-412 ◽  
Author(s):  
Yao Bao Yin ◽  
Ling Li
Keyword(s):  
Equation Of State ◽  
Total Energy ◽  
Negative Energy ◽  
Experimental Results ◽  
Attractive Force ◽  
Positive Energy ◽  
Real Gas ◽  
Thomson Coefficient ◽  
Theoretical Results ◽  
Conversion Temperature

The mechanism of gas cooled or heated through a pneumatic throttle orifice is analyzed. Supposing the total energy of the gas is constant, if the force between the molecules does positive energy, it makes gas heated; if it does negative energy, it makes gas cooled. The conversion temperature of gas is an evaluation parameter for repulsive or attractive force. It has utilized Joule-Thomson coefficient and real gas equation of state to obtain the characteristics of conversion temperature, and the relationships between the molecules distance and the phenomenon of gas cooled or heated after throttle at normal temperature by the conversion characteristics are achieved. The experimental results agreed well with the theoretical results.

scholarly journals Bargmann–Wigner formulation and superradiance problem of bosons and fermions in Kerr space–time

2015 ◽  
Vol 30 (11) ◽  
pp. 1550052 ◽  
Author(s):  
Masakatsu Kenmoku ◽  
Y. M. Cho
Keyword(s):  
Negative Energy ◽  
Space Time ◽  
The Other ◽  
Positive Energy ◽  
Independent Components ◽  
Consistent Description ◽  
Other Hand ◽  
Kerr Space

The superradiance phenomena of massive bosons and fermions in the Kerr space–time are studied in the Bargmann–Wigner formulation. In case of bi-spinor, the four independent components spinors correspond to the four bosonic freedom: one scalar and three vectors uniquely. The consistent description of the Bargmann–Wigner equations between fermions and bosons shows that the superradiance of the type with positive energy (0 < ω) and negative momentum near horizon (p H < 0) is shown not to occur. On the other hand, the superradiance of the type with negative energy (ω < 0) and positive momentum near horizon (0 < p H ) is still possible for both scalar bosons and spinor fermions.

scholarly journals SPINNING PARTICLES ON SPACELIKE HYPERSURFACES AND THEIR REST FRAME DESCRIPTION

1999 ◽  
Vol 14 (09) ◽  
pp. 1429-1484 ◽  
Author(s):  
FRANCESCO BIGAZZI ◽  
LUCA LUSANNA
Keyword(s):  
Spin Structure ◽  
Rest Frame ◽  
Negative Energy ◽  
Nonrelativistic Limit ◽  
Critical Discussion ◽  
Positive Energy ◽  
Spinning Particle ◽  
Spinning Particles ◽  
Spacelike Hypersurfaces ◽  
Energy Formula

A new spinning particle with a definite sign of the energy is defined on spacelike hypersurfaces after a critical discussion of the standard spinning particles. It is the pseudoclassical basis of the positive energy [Formula: see text] [or negative energy [Formula: see text]] part of the [Formula: see text] solutions of the Dirac equation. The study of the isolated system of N such spinning charged particles plus the electromagnetic field leads to their description in the rest frame Wigner-covariant instant form of dynamics on the Wigner hyperplanes orthogonal to the total four-momentum of the isolated system (when it is timelike). We find that on such hyperplanes these spinning particles have a nonminimal coupling only of the type "spin–magnetic field," like the nonrelativistic Pauli particles to which they tend in the nonrelativistic limit. The Lienard–Wiechert potentials associated with these charged spinning particles are found. Then, a comment is made on how to quantize the spinning particles respecting their fibered structure describing the spin structure.

MEDICAL-GEOGRAPHICAL AND RECREATIONAL FEATURES OF THE TERRITORY OF THE IVANO-DOLINSKY BASALT DEPOSIT

2017 ◽  
Author(s):  
Tetіana Basiuk ◽  
◽  
Oksana Romaniv ◽  
Mariya Krynytsʹka ◽  
◽  
...  
Keyword(s):  
Negative Energy ◽  
Health Programs ◽  
Positive Energy ◽  
Educational Organizations ◽  
Number Of Factors ◽  
Permissible Levels ◽  
Geological Phenomenon

The aesthetics of the Ivano-Dolyna basalt deposit and the geological monument of nature "Basalt Pillars" (located within the deposit) has a positive emotional and psychosomatic impact on observers, especially contemplation of the petrified chronicle of the geological phenomenon, visiting the lake with emerald water. Agates of the basalt deposit emit positive energy and are able to absorb negative energy. There is a forest full of phytoncides around the quarries. The basalts of the deposit correspond to the permissible levels of state-regulated radiation parameters. This area deserves to be included in recreation and health programs, and it should be included in the routes of geotourism, not only domestic but also international. The existing and exhausted quarries of the Ivano-Dolyna basalt deposit have a health-improving effect as a cognitive and emotional enrichment during their visit. Taking into account a number of factors, we proposed the development of new types of recreational and tourist products within this area in partnership with environmental, scientific and cultural and educational organizations.

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