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PubMed1986

Measurement of small mechanical vibrations of brain tissue exposed to extremely-low-frequency electric fields.

Electromagnetic fields can interact with biological tissue both electrically and mechanically. This study investigated the mechanical interaction between brain tissue and an extremely-low-frequency (ELF) electric field by measuring the resultant vibrational amplitude. The exposure cell is a section of X-band waveguide that was modified by the addition of a center conductor to form a small TEM cell within the waveguide structure. The ELF signal is applied to the center conductor of the TEM cell. The applied ELF electric field generates an electrostrictive force on the surface of the brain tissue. This force causes the tissue to vibrate at a frequency equal to twice the frequency of the applied sinusoidal signal. An X-band signal is fed through the waveguide, scattered by the vibrating sample, and detected by a phase-sensitive receiver. Using a time-averaging spectrum analyzer, a vibration sensitivity of approximately 0.2 nmp-p can be achieved. The amplitude of the brain tissue vibrational response is constant for vibrational frequencies below 50 Hz; between 50 and 200 Hz resonant phenomena were observed; and above 200 Hz the amplitude fall-off is rapid.

Animals↗
PubMed2003

Electromagnetic field generation by ATP-induced reverse electron transfer.

This paper describes a mechanism to explain low-level light emission in biology. A biological analog of the electrical circuitry, modeled on the parallel plate capacitor, traversed by a helical structure, required to generate electromagnetic radiation in the optical spectral range, is described. The charge carrier required for the emissions is determined to be an accelerating electron driven by an ATP-induced reverse electron transfer. The radial velocity component, the emission trajectory, of the moving charges traversing helical protein structures in a cyclotron-type mechanism is proposed to be imposed by the ferromagnetic field components of the iron in the iron-sulfur proteins. The redox systems NADH, riboflavin, and chlorophyll were examined with their long-wavelength absorption maxima determining the energetic parameters for the calculations. Potentials calculated from the axial velocity components for the riboflavin and NADH systems were found to equal the standard redox potentials of these systems as measured electrochemically and enzymatically. The mechanics for the three systems determined the magnetic moments, the angular momenta, and the orbital magnetic fluxes to be adiabatic invariant parameters. The De Broglie dual wave-particle equation, the fundamental equation of wave mechanics, and the key idea of quantum mechanics, establishes the wavelengths for accelerating electrons which, divided into a given radial velocity, gives its respective emission frequency. Electrons propelled through helical structures, traversed by biologically available electric and magnetic fields, make accessible to the internal environment the optical spectral frequency range that the solar spectrum provides to the external environment.

Adenosine Triphosphate↗
PubMed2004

[Mechanism of biotropic effects of regional electromagnetic fields in patients with left ventricular ischemic dysfunction].

AIM: To study the role of disturbed autonomic regulation of the cardiovascular system in formation of the phenomenon of geliogeomagnetic sensitivity of patients with left ventricular ischemic dysfunction. MATERIAL AND METHODS: 24-h synchronous monitoring of ECG and electromagnetic situation was made in 11 patients (mean age 49.4 +/- 0.9 years) who had survived macrofocal myocardial infarction (MI) at least 6 months before and in 15 healthy volunteers. RESULTS: Heart rhythm dispersion, correlation between variations of magnetic field vector component amplitudes and standard deviation of ECG R-R intervals duration in MI survivors were significantly less than in healthy subjects. High conjugacy of heart rhythm dispersion and mean value of R-R intervals (functions synchronization index) was characteristic only for the control group. A 3-week therapy with atenolol provided normalization of the disturbed correlations in 4 patients. CONCLUSION: Pathogenic geliogeotropic reactions in MI survivors develop because of intra- and inter-systemic desynchronisation of the functions mechanism of which is mediated by sympathicoadrenal activation and is correctable by beta 1-adrenoblocker atenolol.

Adaptation, Physiological↗
PubMed2003

Ultimate intrinsic signal-to-noise ratio for parallel MRI: electromagnetic field considerations.

A method is described for establishing an upper bound on the spatial encoding capabilities of coil arrays in parallel MRI. Ultimate intrinsic signal-to-noise ratio (SNR), independent of any particular conductor arrangement, is calculated by expressing arbitrary coil sensitivities in terms of a complete set of basis functions that satisfy Maxwell's equations within the sample and performing parallel imaging reconstructions using these basis functions. The dependence of the ultimate intrinsic SNR on a variety of experimental conditions is explored and a physically intuitive explanation for the observed behavior is provided based on a comparison between the electromagnetic wavelength and the distance between aliasing points. Imaging at high field strength, with correspondingly short wavelength, is shown to offer advantages for parallel imaging beyond those already expected due to the larger available spin polarization. One-dimensional undersampling of k-space yields a steep drop in attainable SNR for more than a 5-fold reduction of scan time, while 2D undersampling permits access to much higher degrees of acceleration. Increased tissue conductivity decreases baseline SNR, but improves parallel imaging performance. A procedure is also provided for generating the optimal coil sensitivity pattern for a given acceleration, which will serve as a useful guide for future coil designs.

Algorithms↗
PubMed1980

Induction of deep, local hyperthermia by ultrasound and electromagnetic fields: problems and choices.

The feasibility, and the biophysical and engineering concepts underlying the use of electromagnetic energy and ultrasound for production of deep, local hyperthermia are discussed. Focused ultrasound currently is the only modality that can be used for producing controllable levels of hyperthermia localized to deep seated tumors, non-invasively and safely. The ultrasonic focus needs to moved within the tissues around the periphery of the tumor to achieve uniform temperature distributions.

Electromagnetic Phenomena↗

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