摘要:

AbstractAn elementary model consisting of one charged particle in a viscous medium exposed to weak ac‐dc low‐frequency magnetic fields is analyzed to identify and explain the fundamental characteristics of the physical mechanisms that result in a resonance response, which is similar to the familiar cyclotron resonance. The model predicts both frequency and amplitude windows, which are explained in terms of synchronization of the particle with electric fields. Although extrapolation of model results to biological systems is limited by the elementary nature of the model, the model results indicate that observed resonant responses by others of biological systems to ac‐dc magnetic fields are probably not due to resonant response of ions in solution, since the model predicts that no resonant response is possible unless the viscous damping is very low, many orders of magnitude lower than the viscous damping of ions in sol

ISSN:0197-8462    

DOI:10.1002/bem.2250090402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractUnanesthetized rabbits exposed to 12.5‐cm microwaves at a field intensity of 40 mW/cm2in the region of the head showed an increase in the number of slow waves and spindleshaped firings in the EEG and a change in the discharge frequency of neurons in the visual cortex in 41–52% of the cases. An enhancement of the evoked response of visual cortex neurons to light was observed in 61% of the cases and a facilitation of the driving response in 80% of all cases. It is concluded that the evoked response is a more sensitive indicator of the microwave effect than background activity. The effects of the fields were most distinctly observed with the driving respo

ISSN:0197-8462    

DOI:10.1002/bem.2250090403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractMicrowave radiation decreased specific camphor binding to a membrane fraction of rat epithelium but not to a Triton X‐100 extract of this fraction. Inhibition of the ligand binding did not depend on the modulation frequency of the microwave field in the region 1–100 Hz and was not a linear funcion of specific absorption rate (SAR). The decreased ligand binding was due to a shedding or release of the specific camphor‐binding protein from the membrane into solution. It is highly probable that several other membrane proteins may be shed into solution during microwave exp

ISSN:0197-8462    

DOI:10.1002/bem.2250090404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractSodium‐dependent high‐affinity choline uptake was measured in the striatum, frontal cortex, hippocampus, and hypothalamus of rats after acute exposure (45 min) to pulsed (2 μs, 500 pps) or continuous‐wave 2, 450‐MHz microwaves in cylindrical waveguides (Guy et al.: Radio Science 14:63–74, 1979) or miniature anechoic chambers (Guy: Journal of Microwave Power 14:327–338, 1979). In all exposure conditions, the average whole‐body specific absorption rate was at 0.6 W/kg. Decrease in choline uptake was observed in the frontal cortex after microwave exposure in all of the above irradiation conditions. Regardless of the exposure system used, hippocampal choline uptake was decreased after exposure to pulsed but not continuous‐wave microwaves. Striatal choline uptake was decreased after exposure to either pulsed or continuous‐wave microwaves in the miniature anechoic chamber. No significant change in hypothalamic choline uptake was observed under any of the exposure conditions studied. We conclude that depending on the parameters of the radiation, microwaves can elicit specific and generalized

ISSN:0197-8462    

DOI:10.1002/bem.2250090405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe behavior of cultured myotubes from chick embryos exposed to microwaves has been experimentally analyzed. Recordings of acetylcholine‐induced currents have been obtained via patch‐clamp techniques using both cell‐attached (single‐channel current recording) and whole‐cell (total current recording) configurations. During the exposure to low‐power microwaves the frequency of the ACh‐activated single channel openings decreased, while the ACh‐induced total current showed a faster falling phase. Channel open time and conductance were not affected by microwave irradiation. It is concluded that the exposure to microwaves increases the rate of desensitization and decreases the channel opening probability. The nonthermal origin and the molecular interaction mechanisms governing these electromagnetic‐induced effe

ISSN:0197-8462    

DOI:10.1002/bem.2250090406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractResults are presented of an investigation on electric and magnetic fields leaking from inductive (magnetic) heaters that are used for thermal processing of high‐power electron tubes and lasers in an industrial plant. Measurements of electric and magnetic fields were done using both commercially available and laboratory‐developed instrumentation. Isotropic H‐field sensors were developed to allow quantitative evaluation of high‐intensity magnetic fields. Ten induction heaters with nominal A.C. power ranging from 2.5 kW to 15 kW and operating at frequencies between 300 kHz and 790 kHz were surveyed. Electric field strengths up to 8 kV/m and magnetic field strengths up to 20 A/m were m

ISSN:0197-8462    

DOI:10.1002/bem.2250090407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe cyclotron resonance model, recently proposed to account for physiological response to weak environmental magnetic fields, is shown to violate the laws of classical mechanics. Further, it is argued that the ubiquitous presence of dynamic friction in fluid media precludes significant magnetic effects on membrane ion transport.

ISSN:0197-8462    

DOI:10.1002/bem.2250090408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractCyclotron resonance of ions has been proposed as a mechanism by which weak, extremely‐low‐frequency (ELF) electromagnetic fields can act on biological systems. Critics of a mechanism predicated on resonance of lithium have argued that this element is virtually absent from the internal milieu of mammals and otherwise plays no role in the normal physiological functioning of the organism. Sophisticated techniques of trace‐element analysis have recently revealed that lithiumisa normal constituent of tissues of assayed mammals, including those of rats and human beings. There is evidence, too, that lithium is an important, biologically‐active element. Cyclotron resonance may or may not be a mechanism by which ELF‐ and static‐magnetic fields at low strengths combine to affect the organism, but rejection of this mechanism on the grounds that lithium is absent or is physiologically inadequate is unwarranted. Lithium is normally present and is metabolically active in many tissues, especially those of the of the neuroendoc

ISSN:0197-8462    

DOI:10.1002/bem.2250090409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractPulsed, extremely‐low‐frequency electromagnetic fields caused a significant increase in abnormalities in the developing chick embryo. The effect was observed when the field was presented during the first 24 h of incubation; no significant effect was observed with exposure from 24 to 48 h of incubat

ISSN:0197-8462    

DOI:10.1002/bem.2250090410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0197-8462    

DOI:10.1002/bem.2250090411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY