Sinusoidal Electromagnetic Fields Research Articles

Effects of ELF (1-120 Hz) and modulated (50 Hz) RF fields on the efflux of calcium ions from brain tissue in vitro.

We have previously shown that 16-Hz, sinusoidal electromagnetic fields can cause enhanced efflux of calcium ions from chick brain tissue, in vitro, in two intensity regions centered on 6 and 40 Vp-p/m. Alternatively, 1-Hz and 30-Hz fields at 40 Vp-p/m did not cause enhanced efflux. We now demonstrate that although there is no enhanced efflux associated with a 42-Hz field at 30, 40, 50, or 60 Vp-p/m, a 45-Hz field causes enhanced efflux in an intensity range around 40 Vp-p/m that is essentially identical to the response observed for 16-Hz fields. Fields at 50 Hz induce enhanced efflux in a narrower intensity region between 45 and 50 Vp-p/m, while radiofrequency carrier waves, amplitude modulated at 50 Hz, also display enhanced efflux over a narrow power density range. Electromagnetic fields at 60 Hz cause enhanced efflux only at 35 and 40 Vp-p/m, intensities slightly lower than those that are effective at 50 Hz. Finally, exposures over a series of frequencies at 42.5 Vp-p/m reveal two frequency regions that elicit enhanced efflux--one centered on 15 Hz, the other extending from 45 to 105 Hz.

UTILIZAÇÃO DA COMPONENTE VERTICAL DE CAMPOS MAGNÉTICOS ALTERNADOS NA INTERPRETAÇÃO GEOLÓGICA

The theoretical solutions for the behavior of the sinusoidal electromagnetic fields of a plane wave within a two quarter spaces earth are established. The results for the fields, induced by the lateral contrast of conductivity, are given in the form of inverse Fourier cosine transforms. They have been obtained by solving Helmholtz wave equations subject to the proper boundary conditions. Two parameters, the modulus and the argument of the normalized vertical component of the magnetic field intensity, have been computed for five values of the contrast of electrical conductivity, and as a function of induction number. The analysis of the curves obtained for the two parameters shows that: (i) the modulus may be used in the geological interpretation of structures with one vertical contact, and it presents the advantage of being accurately and rapidly measured;(ii) though the argument does not render any aditional information, it may be combined to the modulus to calculate the tilt angle of the polarization ellipse, which is the parameter normally measured in both the AFMAG and VLF methods surveys.

Synthesis and Analysis of Elliptic Polarization Loci in Terms of Space-Quadrature Sinusoidal Components

The general case of elliptic polarization produced by three mutually perpendicular sinusoidal electromagnetic field components at a point in space is treated. The elliptic locus is specified in terms of the sinusoidal components and conversely the components are specified when the locus is known. The simpler two-component case is solved first.