摘要:

AbstractSquirrel monkeys (Saimiri sciureus) trained to regulate environmental temperature (Ta) behaviorally were exposed in the far field of a horn antenna to ten‐minute periods of 2,450 MHzCW microwaves. Incident power density ranged from 1 to 22 mW/cm2. The corresponding specific absorption rate (SAR), derived from temperature increments in saline‐filled styrofoam models, ranged from 0.15 to 3.25 W/kg. Controls included exposure to infrared radiation of equivalent incident energy and no radiation exposure. Normal thermoregulatory behavior produces tight control over environmental and body temperatures; most monkeys select a Taof 34–36°C. Ten‐minute exposures to 2,450 MHzCW microwaves at an incident power density of 6–8 mW/cm2stimulated all animals to select a lower Ta. This threshold energy represents a whole‐body SAR of 1.1 W/kg, about 20% of the resting metabolic rate of the monkey. Thermoregulatory behavior was highly efficient, and skin and rectal temperatures remained stable, even at 22 mW/cm2where the preferred Tawas lowered by as much as 4°C. No comparable reduction in selected Tabelow control levels occurred during exposure to infrared radiation of equal incident

ISSN:0197-8462    

DOI:10.1002/bem.2250010102

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

年代:1980

数据来源: WILEY

摘要:

AbstractTemperature increases due to absorption of 1.2 GHz, CW, 70 mW/cm2, radio frequency (RF) energy, were measured in 3.3‐cm‐radius homogeneous muscle‐equivalent spheres, M. mulatta cadaver heads (both detached from and attached to the body) and living, anesthetized M. mulatta heads. Temperatures were measured with a Vitek, Model 101 Electrothermia Monitor and temperature distributions were compared to theoretical predictions from a thermal‐response model of a simulated cranial structure. The results show that the thermal response model accurately predicts the temperature distribution in muscle‐equivalent spheres, the distribution of temperature in detached M. mulatta heads when exposed from the back of the head, and the distribution of temperature in attached M. mulatta cadaver heads for animals oriented with body parallel to the H‐field. The temperature distribution in the detached M. mulatta heads varies markedly with exposure orientation, ie, facing forward, backward, or to the side. The orientation of the M. mulatta cadaver body significantly affects the temperature distribution in the head ‐ with H‐field orientation showing high, nonuniform values, and E‐field orientation showing low, uniform values. In live animals blood flow produces a significant short‐term effect on the temperature distribution in the midbrain, but not the cortex. Midbrain temperatures are both significantly higher and lower than the comparable cadaver measurements, de

ISSN:0197-8462    

DOI:10.1002/bem.2250010103

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

年代:1980

数据来源: WILEY

摘要:

AbstractChanges have been found in calcium‐ion binding to brain tissue exposed in vitro to a specific power density (0.83 mW/cm2) of 147‐MHz radiation, amplitude modulated by a 16‐Hz sine wave. This report replicates and extends this previous work. To define more precisely the range of effective power densities, two different numbers of samples were treated in a Crawford cell. In one series, four brain tissues were exposed at a time; in the other series, four brain tissues plus six dummy loads were exposed together. While the four‐sample configuration produced a narrow power‐density window, the ten pseudosample configuration resulted in a broader power‐density window. The reason for the sample‐number dependence is unresolved, but may be due to interactions between samples and field distortions caused by the close spacing. The ten pseudosample configuration was used to test for the presence and range of a power‐density window at a sinusoidal modulation frequency of 9 Hz. The response curve at 9 Hz was essentially identical to the results for 16‐Hz si

ISSN:0197-8462    

DOI:10.1002/bem.2250010104

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

年代:1980

数据来源: WILEY

摘要:

AbstractMicrowave‐induced mechanical stress waves were studied in simulated muscle tissue. Pulsed microwave energy at 5.655 GHzinduced pressure waves that were recorded with a hydrophone transducer. Each pulse produced a peak power density greater than 1.5 kW/cm2. Microwave absorption measurements within the model showed energy deposition to be mostly confined to a region within 2 cm of the irradiated surface. The average specific absorption rate (SAR) at the surface of the sample was about 100 W/kg. The microwave‐induced stress wave propagated at a velocity of 1,600 m/sec with peak pressures of approximately 300 pascals and was detectable after having traveled a total distance of 0.61 m on a path that included two reflections at model‐container inter

ISSN:0197-8462    

DOI:10.1002/bem.2250010105

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

年代:1980

数据来源: WILEY

摘要:

AbstractRecently, it has been reported that exposure to high‐strength electric fields can influence electrocardiogram (ECG) patterns, heart rates, and blood pressures in various species of animals. Our studies were designed to evaluate these reported effects and to help clarify some of the disagreement present in the literature. Various cardiovascular variables were measured in Sprague‐Dawley rats exposed or sham‐exposed to 60‐Hz electric fields at 80 or 100 kV/m for periods up to four months. No significant differences in heart rates, ECG patterns, blood pressures, or vascular reactivity were observed between exposed and sham‐exposed rats after 8 hours, 40 hours, 1 month, or 4 months of exposure. Blood pressure and heart rate measurements, made during exposure to a 100‐kV/m electric field for one hour, revealed no significant differences between exposed and sham‐exposed groups. In addition, physiologic reserve capacity, measured in rats subjected to low temperature after exposure to 100 kV/m for one month, showed that electric‐field exposure had no significant effect on physiological response to cold stress. Our studies cannot be directly compared to the work of other investigators because of differences in animal species and electric‐field characteristics. However, our failure to detect any cardiovascular changes may have been the result of 1) eliminating secondary field effects such as shocks, audible noise, corona, and ozone; 2) minimizing steady‐state microcurrents between the mouth of the animal and watering devices; and 3) minimizing electric‐field‐induced vibration of the elec

ISSN:0197-8462    

DOI:10.1002/bem.2250010106

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

年代:1980

数据来源: WILEY

摘要:

AbstractTests of mutagenesis and reproduction were conducted in male rats which were irradiated by 2,450‐MHz, continuous‐wave (CW) microwaves, 4 hr/day from day 6 of gestation to 90 days of age at 5 mW/cm2; or 5 hr/day for five days beginning on the 90th day of age at 10 mW/cm2; or 4 hr/day, 5 days/ wk for four weeks, beginning on the 90th day of age. During selected weekly periods after treatment, the rats were bred to pairs of untreated, normal female rats that were examined in late pregnancy by means of the dominant lethal assay. The reproductive efficiency of these males, as reflected in their breeding, was also examined for changes relating to their microwave experience. No significant evidence of germ‐cell mutagenesis was detected when data of microwave‐exposed males were compared with those of sham‐exposed males, even though there were significant increases in rectal and intra‐testicular temperatures at a power density of 28 mW/cm2. Temporary sterility, as indexed by fewer pregnancies, was seen at the highest po

ISSN:0197-8462    

DOI:10.1002/bem.2250010107

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

年代:1980

数据来源: WILEY

摘要:

AbstractA biphasic modulation of responsiveness of spleen lymphocytes to mitogens was observed in mice exposed to 2,450‐MHz radiation at power densities of 5–15 mW/cm2over various periods ranging between one and 17 days. This modulated phenomenon may be explained on the basis of 1) suppression of lymphocyte response by microwave‐activated macrophages which persists throughout the entire course of radiation, and 2) concurrent progressive direct stimulation of lymphocytes which culminates around day 9 of exposure. Tumor cytotoxicity of killer lymphocytes from mice exposed to five or nine days of radiation did not appear different from sham controls. The highly proliferative hematopoietic marrow cells were sensitive to microwave radiation. Nine days of exposure to radiation (15 mW/cm2) reduced the colonyforming units of myeloid and erythroid series by 50%. This observation may offer a new and more sensitive assay for studying biological effects of electromagnetic radi

ISSN:0197-8462    

DOI:10.1002/bem.2250010108

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe acute effects of microwave exposure on a repeated acquisition baseline were investigated in three rats. Each session the animals acquired a different four‐member response sequence. Each of the first three correct responses advanced the sequence to the next member, and the fourth correct response produced food reinforcement. Incorrect responses produced a three‐second timeout. Baseline and control sessions were characterized by a decrease in errors within each session. The animals were acutely exposed to a 2.8 GHz pulsed‐microwave field prior to test sessions, with average power densities ranging from 0.25 to 10 mW/cm2. In comparison to control sessions, 1/2 hour of exposure to microwave radiation at power densities of 5 and 10 mW/cm2increased errors and altered the pattern of within‐session acquisition. Exposure to the 10 mW/cm2power density decreased the rate of sequence completion in all animals. The results of exposures at 0.25, 0.5, and 1 mW/cm2power densities were generally within the control range. The results are interpreted as indicating a disruption in the discriminative stimulus control of the repeated acquisition b

ISSN:0197-8462    

DOI:10.1002/bem.2250010109

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

年代:1980

数据来源: WILEY

ISSN:0197-8462    

DOI:10.1002/bem.2250010101

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

年代:1980

数据来源: WILEY