摘要:

AbstractThe present study demonstrates that operant behavior is affected by a combination of a 60‐Hz magnetic field and a magnetostatic field 2.6 × 10−5T (about half the geomagnetic field). Rats exposed to this combination for 30 min consistently exhibited changes in the rate and pattern of responding during the differential reinforcement of low rate (DRL) component of a multiple fixed ratio (FR) DRL reinforcement schedule. By contrast, there were no measurable changes following exposure to the static field alone or to the oscillating field alone, even with a 10‐fold increase in intensity (5 × 10−5to 5 × 10−4Trms). A cyclotron resonance mechanism has been suggested as a possible explanation for the observation that weak static magnetic fields modify the response of in vitro brain tissue to low‐frequency magnetic fields. The choice of static field intensity Boand frequencyvin the present study follows from the cyclotron resonance conditionv= (1/2π)(q/m)Bo, for singly charged lithium, an element in extensive use in the clinical treatment of affective disorders in humans. The present research is consistent with a cellular cyclotron resonance mechanism and tends to imply a functional dependence of behavior on the ge

ISSN:0197-8462    

DOI:10.1002/bem.2250070402

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

年代:1986

数据来源: WILEY

摘要:

AbstractThis study was designed to examine the effects of microwaves on the electric activity of hearts as a means of elucidating interactive mechanisms of nonionizing radiations with cardiac tissue. Experiments were performed on isolated hearts of 9–12‐day‐old chick embryos placed in small petri dishes. Oxygenated isotonic Ringer's solution at 37°C permitted heart survival. Samples were irradiatd at 2.45 GHz with a power density of 3 mW/cm2. The heart signal was detected with a glass micropipet inserted into the sinoatrial node and examined by means of a Berg‐Fourier analyzer. Pulsed microwaves caused the locking of the heartbeat to the modulation frequency, whereas continuous wave irradiation might have induced slight bradycardia. Pulsed fields induced stimulation or regularization of the heartbeat in arrhythmia, fibrillation, or arrest of t

ISSN:0197-8462    

DOI:10.1002/bem.2250070403

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe Minnesota Environmental Quality Board completed a 3‐year study of the space charge plume outside the right of way of a bipolar ( +/− 400 kV) direct current transmission line in rural west central Minnesota. The purpose of the study was to determine the levels of DC potential gradient and small air ions in the downwind plume to which humans and animals may be exposed. Potential gradient measurements show that a space charge plume is detectable downwind at least 1600 m from the transmission line. Plume relaxation rates indicate that under certain conditions one could detect the plume at twice that distance or more. Net charge in the plume assumes the polarity of the downwind energized transmission line conductor. The bipolar DC line thus electrically bisects the land through which it passes; on one side of the line there is a net positive space charge, on the other side a net negative space charge. Electric charge in the plume resides on aerosols and small air ions. Polar conductivity data substantiate the fact that small air ions of one polarity in the plume are elevated while those of opposite polarity are suppressed compared to background concentrations found in the rural environment. The resulting charge imbalance persists downwind at least 1600 m, though the median small air ion concentrations of plume polarity have adjusted to within the background range by that time with perpendicular wind speed components between 1 and 6 m/

ISSN:0197-8462    

DOI:10.1002/bem.2250070404

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

年代:1986

数据来源: WILEY

摘要:

Abstract45Ca2+efflux from neonatal isolated chick brains was measured. The brains were exposed to uniform or nonuniform static magnetic fields. The field intensity ranged from 200–900 mT. The exposure took place during incubation and/or when efflux was being measured. No difference appeared in the45Ca2+efflux between controls and exposed brain

ISSN:0197-8462    

DOI:10.1002/bem.2250070405

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe effect of extremely‐low‐frequency pulsed magnetic fields (PMF) on the response of human peripheral blood mononuclear cells to mitogenic stimulation is reported. We investigated 25 healthy control subjects. Mitogen‐stimulated mononuclear cells were exposed to PMF for 72 h and an inhibition of3H‐thymidine uptake was observed in all but one subject. The degree of inhibition of3H‐thymidine uptake was as much as 60%. There was no significant difference between the blastogenic responses of mononuclear cells exposed to PMF for 12 h and control cultures. This study establishes an inhibitory effect of PMF on an in vitro measure of immune

ISSN:0197-8462    

DOI:10.1002/bem.2250070406

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

年代:1986

数据来源: WILEY

摘要:

AbstractThere are two possible mechanisms of effects of large electric fields on animals, one caused by the electric field at the body surface and the other caused by the electric current induced inside the body. The purpose of the present experiments was to investigate the former possibility by recording action potentials from afferent fibers innervating various sensory receptors in the cat's hindlimb. Cat hairs were attracted to the upper electrode when exposed to DC electric fields of 180 kV/m or greater, and action potentials were evoked in the afferent fibers innervating G1, G2, and down hair receptors. No action potentials were evoked in afferent fibers innervating type I, type II, field receptors, muscle spindles, or joint receptors. These results indicate that a strong DC electric field induced movement of the hairs, eventually evoked excitation of the hair receptors, but that other receptors located under the skin were not influenced by electric field exposure.

ISSN:0197-8462    

DOI:10.1002/bem.2250070407

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe combined effects of ethanol and microwaves on the permeation of Evans blue dye through the mammalian blood‐brain barrier was studied in male Wistar rats. Anesthetized rats were infused through a cannula in the left femoral vein with 0.1, 0.3, 0.5 or 0.7 grams of absolute ethanol per kilogram of body mass. A control group was given 0.7 g/kg of isotonic saline. The left hemisphere of the brain was irradiated by 3.15‐GHz microwave energy at 3.0 W/cm2rms for 15 min. The rat's rectal temperature was maintained at 37.0°C. Immediately after irradiation, 2% Evans blue dye in saline (2.0 ml/kg body mass) was injected through the cannula. The results show that as the quantity of alcohol was increased, the degree of staining was decreased or eliminated. The temperature of the irradiated area of the brain increased for the first 4 to 5 minutes of irradiation and then stabilized for the remainder of the irradiation period. The steady‐state temperature was highest in animals receiving saline or the smallest dose of alcohol. As the quantity of alcohol was increased, the steady‐state temperature was reduced. These results indicate that ethanol inhibits microwave‐induced permeation of the blood‐brain barrier through reduced heating

ISSN:0197-8462    

DOI:10.1002/bem.2250070408

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

年代:1986

数据来源: WILEY

摘要:

AbstractDividing human peripheral lymphocytes from 10 normal adults (5 males and 5 females) were exposed in vitro to low level 60‐Hz electromagnetic fields for 69 hours. The current density of the electrical field was 30 μA/cm2, while the magnetic field was either 1 or 2 gauss. The cytological endpoints measured were mitotic rate and chromosome breakage. No statistically significant differences, indicative of a field effect, were observed between treated and control cells whether exposed to an electric field, a magnetic field, or to various combinations of the t

ISSN:0197-8462    

DOI:10.1002/bem.2250070409

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe effects of 50‐, 30‐, and 15‐Hz electric field exposure on the activity of spontaneously firing neurons in the brain of anaesthetized rats were studied. Exposure to fields of 100 V/m (peak‐to‐peak, in air) produced no effect on the overall rate of neuronal firing, but some synchronicity with the period of the exposure waveform was seen with 15‐ and 30‐Hz el

ISSN:0197-8462    

DOI:10.1002/bem.2250070410

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

年代:1986

数据来源: WILEY

ISSN:0197-8462    

DOI:10.1002/bem.2250070411

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

年代:1986

数据来源: WILEY