In this paper we study some examples of magnetic fields with hyperbolic periodic orbits and erratic behavior. The remarkable fact is that the fields under consideration are originated by configurations which consist of two thin wires. We present a rigorous proof of the chaoticity of these magnetic fields, in the sense that they possess KAM islands and homoclinic tangles, and we also provide num...

We analyse the effect of an Ergodic Magnetic Limiter on the magnetic field line dynamics in the edge of a large aspect-ratio Tokamak. We model the limiter action as an impulsive perturbation and use a peaked-current model for the Tokamak equilibrium field. The theoretical analysis is made through the use of invariant flux functions describing magnetic surfaces. Results are compared with a numer...

We recorded the vector magnetogastrogram (MGG) due to gastric electrical activity (GEA) in normal rabbits using a Superconducting QUantum Interference Device (SQUID) magnetometer and measured the degree of correlation of the MGG with 24 channels of serosal electrodes. The vector magnetometer allows us to non-invasively record three orthogonal magnetic field components and project the recorded m...

In the presence of the primordial magnetic field, initial vector (vorticity) perturbations produce cosmological Alfvén waves and leave imprints on cosmic microwave background (CMB) temperature and polarization anisotropy. We have investigated imprints of cosmological Alfvén waves in CMB anisotropy. For data constraints, we have used the power spectrum of the recent CMB observations, and correla...

In Wigner function approach with relaxation time approximation, we calculate electric and magnetic conductivities of a fermion system in the strong field. The linear response has been calculated to perturbation electromagnetic fields on background constant is separated into an equilibrium part field off-equilibrium induced by perturbative fields. analytical expression for corresponding conditio...

An improved version of the perturbation theory has been proposed. Expressions for the wave functions and energies of both degenerate and nondegenerate cases are derived. This method provides a simple way to treat problems involving more than one potential in the Hamiltonian and the case when the perturbations are comparable with or larger than the unperturbed Hamiltonian. We use this method to ...

A perturbative approach is employed to solve the Bloch-Torrey equations in the presence of distant-dipole fields in nuclear magnetic resonance. The procedure, although only carried out to first order in the perturbation parameter a=1/k2Dtaud, could, in principle, be generalized to higher orders. Here D is the diffusivity, taud the dipolar demagnetization time, and k is the wave vector of the sp...

We introduce a ‘‘structure minimization’’ technique to resolve the azimuthal ambiguity of 180 , intrinsic in solar vector magnetic field measurements. We resolve the 180 ambiguity by minimizing the inhomogeneities of the magnetic field strength perpendicular to the magnetic field vector. This relates to a minimization of the sheath currents that envelope the solar magnetic flux tubes, thus allo...

The Landau Hamiltonian, describing the behavior of a quantum particle in dimension 2 in a constant magnetic field, is perturbed by a magnetic field with power-like decay at infinity and a similar electric potential. We describe how the spectral subspaces change and how the Landau levels split under this perturbation.