摘要:

Many issues and controversies separate the experimental radiobiologist and the hygienist from the goal of attaining a concordant view of biological effects of exposure to microwaves and other radio‐frequency electromagnetic (RFEM) fields. Although the strongest notes of discord are struck by East‐West differences (e.g., recommended limits with respect to exposure of human populations to RFEM fields are generally orders of magnitude more stringent in the USSR than in the U.S.), there are discordant notes as well within national boundaries. To the end of achieving a better scientific grasp of problems and solutions the author discusses selected issues under the headings of semantics, tactics, logistics, and strategy. Among the topics discussed are problems of communication, physical measurements in relation to laboratory and regulatory practice, pitfalls of interdisciplinary research, and research needed to achieve ecologically valid d

ISSN:0048-6604    

DOI:10.1029/RS017i05Sp0001S

年代:1982

数据来源: WILEY

摘要:

In November and December 1977 at McMurdo Station in Antarctica we investigated the kinds, numbers, and deposition of airborne particles larger than 2 μm while measuring electric field gradient at 2.5 m above the ground. Elementary collecting devices were used: Staplex Hi‐Volume and Roto‐rod samplers, Tauber (static sedimentation) traps, petrolatum‐coated microscope slides, and snow (melted and filtered). The electric fields were measured by a rotating dipole (Stanford Radioscience Laboratory field mill number 2). During periods of blowing snow and dust the electric field gradient was + 500 to + 2500 V/m, and Tauber traps with grounded covers collected 2 or more times as much snow and dust as the ones with ungrounded covers. During falling snow the electric field gradient was −1000 to −1500 V/m, and the ungrounded traps collected almost twice as much snow and dust as those grounded. These observations suggest that under the prevailing weather conditions in polar regions the probable net effect is deposition of greater quantities of dust, including diaspores and minute organisms, on wet, grounded surfaces. This hypothesis needs examination for its use in explanation of biological distributio

ISSN:0048-6604    

DOI:10.1029/RS017i05Sp0013S

年代:1982

数据来源: WILEY

摘要:

Frohlich's concept of coherently excited long‐wavelength electric vibrations in the 1011to 1012‐Hz region associated with metastable states with a very high dipole moment in biological membranes has been the basis for explaining the extraordinary high sensitivity of certain biological systems to extremely weak electromagnetic signals. In this model, long‐range collective interactions within the membranes may lead to oscillatory biochemical reactions (e.g., enzyme‐substrate interactions in the greater membrane of the brain.) The resulting slow chemical oscillation is connected to a corresponding electric vibration by means of the large dipole moments of reaction‐activated enzymes. Thus a macroscopic oscillating polarization is built up, causing large regions to oscillate coherently in the 10 to 100‐Hz region (e.g., EEG activity). The remaining (unscreened) polarization causes the system to exhibit a ferroelectric instability. The nonlinear kinetic equations describing the system are discussed. Extremely low frequency fields interact with the limit cycle oscillation, which is caused to collapse for certain frequencies and intensities of the stimulation. This leads to the onset of propagating pulses even for an extremely weak stimulation. There is increasing experimental evidence for the rather speculative predictions. Furthermore, correspondence between this model and nerve impulse‐generating models has bee

ISSN:0048-6604    

DOI:10.1029/RS017i05Sp0017S

年代:1982

数据来源: WILEY

摘要:

The aim of the paper is to review quantum solid state mechanisms of nonthermal (specific) bioeffects of nonionizing radiation and to present the author's own hypothesis concerning mechanisms based on biological superconductivity. Classical and quantum mechanisms of bioeffects are compared stressing the necessity of not only considering quantum absorption, transfer, and conversion of radiation energy in biological systems, but also of appropriate systems modeling. The need is stressed for developing quantum models of the biological solid state on the supramolecular level to fill the gap between molecular and cell biology. The supramolecular models of macromolecules and enzyme complexes will be reviewed. The high‐temperature superconductivity problem in organic systems will be discussed with stress on the importance of system structure and the excitation quasi‐particle (phonon and electron) spectra relationship. New mechanisms of enzymatic activity assuming enzyme‐substrate complex electron spectrum instability induced by electron‐ and phonon‐mediated electron‐electron interaction are proposed. Since this quantum cooperative phenomenon is the possible origin of specificity and efficiency of enzyme action it is extremely sensitive to system‐generated electromagnetic fields, which gives the possibility of enzymatic regulation and also may explain some nonthermal resonant bioeffects. Local superconductivity (coherent electron states) and Josephson effects as the possible mechanisms of bioeffects

ISSN:0048-6604    

DOI:10.1029/RS017i05Sp0023S

年代:1982

数据来源: WILEY

摘要:

The present paper describes the results of measurements of electric and magnetic stray fields around three types of commercially available diathermy units with four very typical electrodes in six routine therapeutic treatments. The aim of the survey was to investigate the exposure to the physiotherapist and the exposure to unprescribed tissues. Field strengths were measured at 15 points close to the patient's body. At a distance of 0.6 m from the diathermy units the power density was less than 10 W/m2. With respect to stray fields the results showed that the diathermy devices are very similar but there are great differences between the electrodes during specific treatments. The results assist in selecting proper electrodes for various therapeutic treatments, as they indicate which electrodes would have minimal stray fields.

ISSN:0048-6604    

DOI:10.1029/RS017i05Sp0029S

年代:1982

数据来源: WILEY

摘要:

All the measurements were performed in the working positions at the machines. Field flux densities in the range 0–10 mT at mostly 50 Hz were found in both types of industries. Near induction heaters, both the magnetic flux density and the frequency may be very high (up to 10 kHz). Knowledge of industrial field characteristics such as frequency, flux density, and distribution will facilitate laboratory research aimed at determining possible biological effects of magnetic fields. These results indicate that biological effects of the magnetic fields probably occur (magnetophosphenes), although these phenomena are difficult to recognize in industrial localities with high background illuminatio

ISSN:0048-6604    

DOI:10.1029/RS017i05Sp0035S

年代:1982

数据来源: WILEY

摘要:

The U.S. Environmental Protection Agency has been collecting broadcast signal field intensity data for over 2 years to estimate population exposure to this form of nonionizing radiation. Measurement data have been obtained at 373 locations distributed throughout 12 large cities and collectively represent approximately 11,000 measurements of VHF and UHF signal field intensities. The VHF and UHF broadcast service is the main source of ambient radio frequency exposure in the United States. A computer algorithm has been developed which uses these measurement data to estimate the broadcast exposure at some 39,000 census enumeration districts within the metropolitan boundaries of these 12 cities. The results of the computations provide information on the fraction of the population that is potentially exposed to various intensities of radio frequency radiation. Special emphasis has been placed on determining the uncertainty inherent to the exposure estimation procedure, and details are provided on these techniques. A median exposure level (half of the population is exposed to greater than the median level) of 0.005‐μ W/cm2time‐averaged power density has been determined for the population of the 12 cities studied, the cumulative population of which represents 18% of the total United States population. The data also suggest that approximately 1% of the population studied, or about 380,000, is potentially exposed to levels greater than 1 μ W/cm2, the suggested safety guide for the population in the USSR. Alternative techniques of using the measurement data to estimate population exposure are examined, and future extensions of this work are disc

ISSN:0048-6604    

DOI:10.1029/RS017i05Sp0039S

年代:1982

数据来源: WILEY

摘要:

An implantable electric field probe with an interference‐free lead wire system was constructed at a nominal cost for the purpose of measuring the induced electric fields in a phantom model of man irradiated by waves of various frequencies. The probe consisted of a short dipole loaded with a zero‐bias microwave diode, and the interference‐free lead wires were constructed with two series of lumped resistors of 3 k Ω. Characteristics of the probe were checked first by measuring the induced electric fields in irradiated, electrically small cubes filled with phantom material. The measured results were in good agreement with theoretical results obtained from the tensor integral equation method. A phantom model of man was constructed with thin Plexiglas filled with phantom material. The model was irradiated by 500‐ to 3000‐MHz em waves in a microwave anechoic chamber. Induced electric fields were probed over 28 locations in one side of the model. The distribution of the measured electric fields was compared with the distribution of theoretical results obtained numerically from the tensor integral equation methods. A qualitative agreement was obtained between experiment and theory. It was found that the agreement between experiment and theory tended to deteriorate at lower frequencies. The reason for this discrepancy is

ISSN:0048-6604    

DOI:10.1029/RS017i05Sp0049S

年代:1982

数据来源: WILEY

摘要:

A new theoretical method for determining the electric field or the eddy current induced by a uniform RF magnetic field or a beam of RF magnetic field in a biological body of rotational symmetry is presented. The body is subdivided into a number of circular rings with various radii and cross‐sectional areas. The induced electric field or eddy current in each ring is then numerically determined on the basis of the theory of vector potential and the moment method. Numerical examples are given, and the results based on the present theory are found to deviate significantly from the often used, quasi‐static solutions. An experiment was conducted to measure the electric fields induced by a UHF magnetic field in phantom biological models. The theory was verified by the experiment and the existing theoretical resu

ISSN:0048-6604    

DOI:10.1029/RS017i05Sp0061S

年代:1982

数据来源: WILEY

摘要:

Analysis of the near‐field irradiation of prolate spheroidal models of humans and animals by a small coaxial loop antenna is described. The near fields of the antenna are known exactly and hence are used to identify the suitable field parameters involved in the near‐field absorption in the spheroidal model. An integral equation is formulated in terms of the transverse dyadic Green's function, and the fields radiated by the current loop are expanded in terms of the vector spherical harmonics. The extended boundary condition method is then employed to solve the integral equation. The power distribution and the average specific absorption rate (SAR) are calculated and plotted, for different human and animal models, as a function of the separation distance from the loop. It is shown that for distances less than 5λ the average SAR values oscillate about the far‐field value. In particular, ford/λ<0.4 an increase in the average SAR values was generally observed. It is also shown that in spite of the complicated nature of the near fields the absorption characteristics can still be explained in terms of the incident radiation. Furthermore, from the calculated SAR distributions at different frequencies it is shown that at all frequencies, excessive heating occurs at the surface of the spheroid while a limited absorption occurs in the central region around the major axis. This result is of particular importance in hyperthermia, where extensive efforts are being directed toward achieving deep‐tissue heating by a coaxial coil carrying RF power at abo

ISSN:0048-6604    

DOI:10.1029/RS017i05Sp0077S

年代:1982

数据来源: WILEY