摘要:

AbstractMeasurements have been made of vector current densities induced by vertical, uniform, 60‐Hz electric fields in the torsos of homogeneous models of swine and rats. The observed data were a strong function of the five grounding configurations invested: all four feet grounded, only front feet grounded, only rear feet grounded, left front and right rear feet grounded, and right front and left rear feet grounded. In the first configuration and with an exposure field strength of 10 kV/m, average total current densities induced in the torsos of pigs and rats were 34 nA/cm2and 20 nA/cm2, respectively. The corresponding value for human exposure is about 250 nA/cm2, 7.3 and 12.5 times larger than for swine and rats, respectively. Current densities measured at 60 Hz can be linearly extrapolated to frequencies in a range extending from at least 1 Hz to 1 MHz. Human and animal current‐density data can provide an improved rationale for extrapolating biological data across species. In addition, these data can be used to validate the predictions of numerical mod

ISSN:0197-8462    

DOI:10.1002/bem.2250090102

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

年代:1988

数据来源: WILEY

摘要:

AbstractForty male rats of the Wistar ST strain were trained and observed for Sidman avoidance (SA) for 7 weeks or for discriminative avoidance (DA) for 14 weeks to determine the effects of exposure to a strong static‐magnetic field. Before avoidance conditioning was completed, rats in the SA group were exposed to the static field at 0.6 T, 16 h/day for 4 days during the fifth week, and those in the DA group were exposed for 6 h/day for 4 days during the seventh week. In the SA conditioning, frequency of lever‐pressing by exposed rats gradually decreased during 1 week of exposure and stayed low for at least 2 weeks after exposure. Frequencies of electric shocks received by the rats increased dramatically during the second day of exposure and consistently stayed higher than those of control rats. In the DA condition, exposed rats responded at lower rates than did control rats throughout the observation period. They received more shocks during the 2 weeks following exposure. The data indicate that performance of avoidance responses was inhibited by a comparatively long exposure to a strong magnetic fi

ISSN:0197-8462    

DOI:10.1002/bem.2250090103

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe cyclotron resonance model for channel ion transport in weak magnetic fields is extended to include damping losses. The conductivity tensor is obtained for different electric field configurations, including the circuital fieldEΦnormal to the channel axis. The conductivity behavior close to the cyclotron resonance frequency ωcis compared to existing Ca2+‐efflux data in the literature. A collision time of .023 s results from this comparison under the assumption that K+ions are transiting in a 0.35 G field. We estimate a mean kinetic energy of 3.5 eV for this ion at resonance. This model leads to discrete modes of vibration (eigenfrequencies) in the ion‐lattice interaction, such that ωn= nωc. The presence of such harmonics is compatible with recent results by Blackman et al. [1985b] and McLeod et al. [1986]with the interesting exception that even modes do not appear in their observations, whereas the present model has no restriction on n. This harmonic formalism is also consistent with another reported phenomenon, that of quantized multiple conductances in single patch‐clamped

ISSN:0197-8462    

DOI:10.1002/bem.2250090104

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

年代:1988

数据来源: WILEY

摘要:

AbstractRats with skin‐wounds surgically created on their backs were exposed immediately after surgery and every 12 h thereafter to pulsed, extremely‐low‐frequency magnetic fields. The shape of the pulse was a positive triangle (50 Hz, 8 mT peak). The rate of healing of skin wounds was evaluated macroscopically and by light and electron microscopy at 6, 12, 21, and 42 days after the operation. A significant increase in the rate of wound contraction was found in rats treated with magnetic fields. Forty‐two days after surgery all treated animals show fully closed wounds, while control rats at the same time intervals still lacked a final 6% of the wound surface to be covered. Treated rats showed earlier cellular organization, collagen formation and maturation, and a very early appearance of newly formed vascular

ISSN:0197-8462    

DOI:10.1002/bem.2250090105

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

年代:1988

数据来源: WILEY

摘要:

AbstractFour experiments were conducted to quantify the reported attenuation by microwave (MW) irradiation of ethanol‐induced hypothermia. In one experiment rats were irradiated (continuous wave 2.45 GHz, specific absorption rate = 0.3 W/kg) or sham irradiated for 45 min, injected with 3.6 g/kg, 20% (v/v) ethanol (EtOH) or saline (NaCl) i.p. Colonic temperature was monitored at 20‐min intervals for 2 h. This procedure was repeated for 8 days to determine the rate of tolerance development to the hypothermic effect of ethanol. While MW irradiation did significantly attenuate EtOH‐induced hypothermia, it did not enhance or retard the rate of tolerance development. To determine the duration of irradiation necessary to attenuate EtOH‐induced hypothermia, groups of rats were irradiated or sham irradiated for 5, 15, 30, or 60 min prior to EtOH injection and subsequent temperature measurements. The attenuation was apparent only after 60 min of irradiation. To determine the duration of the attenuation effect after irradiation, rats were injected with EtOH or NaCl at 0, 30, 60, 120, or 480 min after 45 min of irradiation or sham irradiation. The attenuation effect was apparent among rats injected 0 to 30 min after irradiation and for the first 40 min for groups injected at 120 min. Additional rats were injected with NaCl or 0.9, 1.8, or 2.7 g/kg of EtOH i.p. following 45 min of irradiation or sham irradiation to determine if the attenuation effect depends on the dose of EtOH administered. Attenuation of EtOH‐induced hypothermia was more apparent at lower doses of EtOH than at higher doses. These results indicate that the effect is an acute response to irradiation, and rule out several other potential exp

ISSN:0197-8462    

DOI:10.1002/bem.2250090106

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

年代:1988

数据来源: WILEY

摘要:

AbstractSpecific absorption rate (SAR) and effective depths of heating patterns induced by a shortwave, pancake diathermy applicator in fat‐muscle phantom are measured. Midplane partitions of polyethylene and silk screen with and without contact chemicals are used. Thermographically obtained SAR data show nearly the same value for silk‐screen partitions with and without contact chemicals and slightly lower values with polyethylene partitions, provided that the partition midplanes are tightly pressed against each other. Thermometry data indicate that for low‐power exposures the major error in thermographic measurements obtained after termination of heating is due to thermal diffusion and not evaporative cooling in the opened midplane of the ph

ISSN:0197-8462    

DOI:10.1002/bem.2250090107

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

年代:1988

数据来源: WILEY

摘要:

AbstractOne of the fundamental inputs to models of population exposure to the power‐frequency fields of high‐voltage transmission lines is the density of population about the lines. We examined aerial photographs of over 1,700 km of transmission corridor to characterize the density of nearby housing units. The data show that the density of houses within 200 m of transmission lines (1) is typically smaller than the average density of houses in the local utility's service area, (2) tends to increase with distance from the line, and (3) is inversely correlated with line volt

ISSN:0197-8462    

DOI:10.1002/bem.2250090108

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

年代:1988

数据来源: WILEY

摘要:

AbstractBody growth and circulating levels of hormones were assessed in young rats and rabbits exposed to a 50‐Hz electric field of 50 kV/m. Eight‐week‐old male rats were exposed 8 h/ day for 4 weeks and rabbits were exposed 16 h/day from the last 2 weeks of gestation to 6 weeks after birth. The body and the organ growth of exposed rats were not statistically different from those of sham‐exposed controls. No important differences from controls were observed in plasma levels of corticosterone, TSH, ACTH, and T4or in adrenal levels of epinephrine, norepinephrine, and corticosterone although T3was slightly, but significantly, decreased. No large histological changes in the thyroid or adrenals were noted. In rabbits, organ and body wieghts of exposed animals were comparable to those of controls. Plasma levels of various hormones (ACTH, GH, T3, T4, corticosterone, cortisol), serum glucose, triglycerides, and cholesterol were not significantly altered. Adrenal content of cortisol was lower, however, in exposed rabbits. No histological changes of the thyroid or adrenal glands were o

ISSN:0197-8462    

DOI:10.1002/bem.2250090109

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe effect of low‐level microwave exposure, 2,450 MHz, at a power density of 1 mW/cm2and specific absorption rate of 1.2 mW/g, continuous waves (CW) or pulsed waves (PW), 2.5 h/day, 6 sessions/week until death (up to 690 h of irradiation), has been studied in black C57/6J mice with B16 melanoma. The results show that no significant effects are observed on tumor development or on survival times compared to controls, or between CW‐ and PW‐treated an

ISSN:0197-8462    

DOI:10.1002/bem.2250090110

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.2250090101

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

年代:1988

数据来源: WILEY