The nonlinear dynamics of magnetic helicity HM, which is responsible for large-scale magnetic structure formation in electrically conducting turbulent media, is investigated in forced and decaying three-dimensional magnetohydrodynamic turbulence. This is done with the help of high-resolution direct numerical simulations and statistical closure theory. The numerically observed spectral scaling o...

background: to reduce the dose to normal tissues surrounding the treated breast, a uniform magnetic field was used within a humanoid phantom in breast radiotherapy. materials and methods: monte carlo simulations were performed with geant4, irradiating humanoid phantoms in a magnetic field. to reconstruct phantoms, computed tomography (ct) data slices of four patients were used for the monte car...

The electric field parallel to the magnetic field, E∥, in nonlinear magnetosonic waves is analytically studied. The theory shows that E∥ can be strong. Then, with use of one-dimensional, fully kinetic, relativistic, electromagnetic, particle simulations and with test particle calculations, the effect of E∥ on particle acceleration in shock waves is examined for three different mechanisms: inces...

Recent analytical and computational advances in the theory of large-scale dynamos are reviewed. The importance of the magnetic helicity constraint is apparent even without invoking mean-field theory. The tau approximation yields expressions that show how the magnetic helicity gets incorporated into mean-field theory. The test-field method allows an accurate numerical determination of turbulent ...

the exposure of workers to magnetic field that occur in aluminum reduction potrooms has been studied. the pattern of magnetic field intensity has been demonstrated along the shop. it has clearly been shown that the personnel working near the pots are exposed to 20-to 1000-gauss magnetic field. to set limits of exposure to magnetic fields, the literature on the biological effects of stationary m...

An explicitly time dependent equation for the alpha-effect in mean field dynamo theory is employed to ensure that the magnetic helicity equation for the total (small and large scale) magnetic field is obeyed exactly. The dependence of the turbulent magnetic diffusivity on the field strength is unconstrained by magnetic helicity conservation and is therefore employed as a free parameter. The app...

Using direct simulations, weakly nonlinear theory and nonlinear mean-field theory, it is shown that the quenched velocity field of a saturated nonlinear dynamo can itself act as a kinematic dynamo. The flow is driven by a forcing function that would produce a Roberts flow in the absence of a magnetic field. This result confirms an analogous finding by F. Cattaneo & S. M. Tobias (arXiv:0809.1801...

A widely held viewpoint in optics, namely, that dynamic magnetic effects are extremely weak at optical frequencies, is re-examined. Nonlinear charge motion induced by the optical magnetic field in dielectric systems is analyzed, is predicted to be resonantly enhanced, and is observed experimentally in CCl4, C6H6, and H2O at the fundamental input frequency. Excellent agreement is obtained with a...

in this paper we studied the thermal negativity in a two-qubit xx spin ½ chain model and xxx spin1/2 chain model(isotropic heisenberg model)spin-1/2 chain subjected to an external magnetic field inz direction. we calculate analytical relation for the thermal negativity for two qubit xx and xxx spinchain models in the external magnetic field. effects of the magnetic field and temperature on then...