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  • Occupational Health and Environmental Toxicology
  • Wiley-Blackwell  (37)
  • American Chemical Society (ACS)
  • 1980-1984  (37)
  • 1980  (37)
Collection
Publisher
  • Wiley-Blackwell  (37)
  • American Chemical Society (ACS)
Years
  • 1980-1984  (37)
Year
  • 1
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 1 (1980), S. 285-298 
    ISSN: 0197-8462
    Keywords: absorption ; millimeter wave ; biological media ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: A solid-state computer-controlled system has been used to make swept-frequency measurements of absorption of biological specimens from 26.5 to 90.0 GHz. A wide range of samples was used, including solutions of DNA and RNA, and suspensions of BHK-21/C13 cells, Candida albicans, C krusei, and Escherichia coli. Sharp spectra reported by other workers were not observed. The strong absorbance of water (10-30 dB/mm) caused the absorbance of all aqueous preparations that we examined to have a water-like dependence on frequency. Reduction of incident power (to below 1.0 μW), elimination of modulation, and control of temperature to assure cell viability were not found to significantly alter the water-dominated absorbance. Frozen samples of BHK-21/C13 cells tested at dry ice and liquid nitrogen temperatures were found to have average insertion loss reduced to 0.2 dB/cm but still showed no reproducible peaks that could be attributed to absorption spectra. It is concluded that the spectral resonances reported by others are likely to be in error.
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  • 2
    ISSN: 0197-8462
    Keywords: calcium ions ; brain tissue ; radiofrequency (RF) radiation ; amplitude modulation ; power-density window ; 16-Hz modulation ; 50 MHz ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: In previous experiments changes were found in calcium-ion efflux from chickbrain tissue that had been exposed in vitro to 147-MHz radiation across a specific range of power densities when the field was amplitude modulated at 16 Hz. In the present study, 50-MHz radiation, similarly modulated as a sinusoid, was found to produce changes in calcium-ion efflux from chick brains exposed in vitro in a Crawford cell. Exposure conditions were optimized to broaden any power-density window and to enhance the opportunity to detect changes in the calcium-ion efflux. The results of a power-density series demonstrated two effective ranges: One spanning a range from 1.44 to 1.67 mW/cm2, and the other including 3.64 mW/cm2, which were bracketed by no-effect results at 0.72, 2.17, and 4.32 mW/cm2. Peaks of positive findings are associated with near-identical rates of energy absorption: 1.4 μW/g at 147 MHz, and 1.3 μW/g at 50 MHz, which indicates that the enhanced-efflux phenomenon is more dependent on the intensity of fields in the brain than on the power density of incident radiation. In addition, the phenomenon appears to occur at multiples of some, as yet unknown, rate of radiofrequency (RF) energy absorption. Because of the extremely small increments of temperature associated with positive findings (〈 4 × 10-4°C), and the existence of more than one productive absorption rate, a solely thermal explanation appears extremely unlikely.
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  • 3
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    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 1 (1980) 
    ISSN: 0197-8462
    Keywords: Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
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  • 4
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    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 1 (1980), S. 1-20 
    ISSN: 0197-8462
    Keywords: 2,450 MHz CW microwaves ; behavioral thermoregulation ; body temperature ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Squirrel 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 MHz CW 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 Ta of 34-36°C. Ten-minute exposures to 2,450 MHz CW microwaves at an incident power density of 6-8 mW/cm2 stimulated 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/cm2 where the preferred Ta was lowered by as much as 4°C. No comparable reduction in selected Ta below control levels occurred during exposure to infrared radiation of equal incident power density.
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  • 5
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    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 1 (1980), S. 45-54 
    ISSN: 0197-8462
    Keywords: pulsed microwaves ; thermoelastic waves ; simulated tissue ; hydrophone ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Microwave-induced mechanical stress waves were studied in simulated muscle tissue. Pulsed microwave energy at 5.655 GHz induced 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 interfaces.
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  • 6
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    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 1 (1980), S. 117-129 
    ISSN: 0197-8462
    Keywords: electric fields ; 60 Hz ; biological effects ; dosimetry ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Published and new data for grounded humans, swine, and rats exposed to vertical, 60-Hz electric fields are used to determine field strengths at the surfaces of the bodies and average components of induced-current density along the axes of the bodies. At the tops of the bodies, surface electric fields are increased (enhanced) over the unperturbed field strength present before the subjects entered the field by factors of 17,7, and 4 for humans, swine, and rats, respectively. For an unperturbed field strength of 10 kV/m, average induced axial current densities in the neck, chest, abdomen, and feet are: 550, 190, 250, and 2000 nA/cm2, respectively, for humans; 40, 13, 20, and 1100 nA/cm2, respectively, for swine; and 28, 16, 2, and 1400 nA/cm2, respectively, for rats. These data are used to show that the actual electric fields experienced by animals depend strongly on the shape of the body and its orientation relative to the electric field and ground plane. This fact must be taken into account if biological data obtained with laboratory animals are to be used for the assessment of possible hazards to humans exposed to 60-Hz electric fields.
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  • 7
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    Bioelectromagnetics 1 (1980), S. 149-160 
    ISSN: 0197-8462
    Keywords: microwaves ; microwave dosimetry ; rhesus monkey dosimetry ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Dosimetric measurements were made in a muscle-equivalent model of an adult rhesus monkey subjected to far-field irradiation at 1.29 GHz. Profiles of microwave-induced heating in the model were obtained at eight locations, and a gradient-layer whole-body calorimeter was used to measure total absorbed energy. Average specific absorption rate (SAR) was calculated both from the calorimeter experiments and from the local temperature measurements. Thermographic imaging techniques were used to qualitatively show the microwave-induced surface heating patterns. For this model the calculated average SAR was 0.155 (W/kg)/(mW/cm2) which, at 1.29 GHs, makes the absorption cross section 84% of the geometric shadow cross section. The SAR is about three times that predicted for a prolate spheroidal model of similar mass. A disproportionally high absorption occured in the legs of the model positioned parallel to the E-polarization because of what is believed to be partial-body resonance.
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  • 8
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    Bioelectromagnetics 1 (1980), S. 131-147 
    ISSN: 0197-8462
    Keywords: electric fields ; rat ; sciatic nerve ; vagus nerve ; superior cervical sympathetic ganglion ; chronic exposure ; 60 Hz ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Several reports have suggested that the nervous system can be affected by exposure to electric fields and that these effects may have detrimental health consequences for the exposed organism. The purpose of this study was to investigate the effects of chronic (30-day) exposure of rats to a 60-Hz, 100-kV/m electric field on synaptic transmission and peripheral-nerve function. One hundred forty-four rats, housed in individual polycarbonate cages were exposed to uniform, vertical, 60-Hz electric fields in a system free of corona discharge and ozone formation and in which the animals did not receive spark discharges or other shocks during exposure. Following 30 days of exposure to the electric field, superior cervical sympathetic ganglia, vagus and sciatic nerves were removed from rats anesthetized with urethan, placed in a temperature-controlled chamber, and superfused with a modified mammalian Ringer's solution equilibrated with 95% O2 and 5% CO2. Several measures and tests were used to characterize synaptic transmission and peripheral-nerve function. These included amplitude, area, and configuration of the postsynaptic or whole-nerve compound-action potential; conduction velocity; accommodation; refractory period; strength-duration curves; conditioning-test (C-T) response, frequency response; post-tetanic response; and high-frequency-induced fatigue. The results of a series of neurophysiologic tests and measurements indicate that only synaptic transmission is significantly and consistently affected by chronic (30-day) exposure to a 60-Hz, 100-kV/m electric field. Specifically, an increase in synaptic excitability was detected in replicated measurements of the C-T response ratio. In addition, there are trends in other data that can be interpreted to suggest a generalized increase in neuronal excitability in exposed animals.
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  • 9
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    Bioelectromagnetics 1 (1980), S. 199-251 
    ISSN: 0197-8462
    Keywords: Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
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  • 10
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    Bioelectromagnetics 1 (1980), S. 161-170 
    ISSN: 0197-8462
    Keywords: microwave bioeffects ; nonionizing radiation ; lymphoid cell metabolism ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: CBA/J adult male mice were given single or triple exposures to 2450-MHz microwaves in an environmentally controlled wave guide facility. The average absorbed dose rate for a single exposure varied from 12 to 15 mW/g. Shamexposed mice served as controls. Lymphoid cells were collected and tested for metabolic activity on days 3, 6, and 9 following a single exposure, and on days 9, 12, and 16 following triple exposures on days 0, 3, and 6. Cells were cultured in vitro for four hours to seven days before their metabolic rates were assayed. Under these conditions, microwaves failed to produce any detectable change in deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and protein synthesis, as measured by the incorporation of methyl(3H)-thymidine (3H-TDR) (DNA substrate), 3H-uridine (3H-UR) (RNA substrate), and 3H-leucine (protein substrate) by spleen, bone marrow, and peripheral blood lymphocytes (PBL) in vitro. These data suggest that microwave-induced increases in the frequency of complement-receptor (CR)- or surface-immunoglobulin (sIg)-bearing cells were not associated with a concomitant increase in cell proliferation and/or protein synthesis, and favor the concept that microwaves under these conditions stimulate already existing B-cell precursors for maturation.
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  • 11
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    Bioelectromagnetics 1 (1980), S. 183-198 
    ISSN: 0197-8462
    Keywords: operant behavior ; observing-responses ; microwaves ; vigilance ; dosimetry ; rats ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The effects of microwave irradiation at two different frequencies (1.28 and 5.62 GHz) on observing-behavior of rodents were investigated. During daily irradiation, eight male hooded rats performed on a two-lever task; depression of one lever produced one of two different tones and the other lever produced food when depressed in the presence of the appropriate tone. At 5.62 GHz, the observing-response rate was not consistently affected until the power density approximated 26 mW/cm2 at 1.28 GHz, the observing-response rate of all rats was consistently affected at a power density of 15 mW/cm2. The respective whole-body specific absorption rates (SARs) were 4.94 and 3.75 W/Kg. Measurements of localized SAR in a rat-shaped model of simulated muscle tissue revealed marked differences in the absorption pattern between the two frequencies. The localized SAR in the model's head at 1.28 GHz was higher on the side distal to the source of radiation. At 5.62 GHz the localized SAR in the head was higher on the proximal side. It is concluded that the rat's observing behavior is disrupted at a lower power density at 1.28 than at 5.62 GHz because of deeper penetration of energy at the lower frequency, and because of frequency-dependent differences in anatomic distribution of the absorbed microwave energy.
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  • 12
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    Bioelectromagnetics 1 (1980), S. 171-181 
    ISSN: 0197-8462
    Keywords: microwaves ; in vivo ; brain ; adenosine triphosphate (ATP) ; creatine phosphate (CP) ; NADH ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Rat brain was exposed to 591-MHz, continuous-wave (CW) microwaves at 13.8 or 5.0 mW/cm2 to determine the effect on nicotinamide adenine dinucleotide, reduced (NADH), adenosine triphosphate (ATP) and creatine phosphate (CP) levels. On initiation of the in vivo microwave exposures, fluorimetrically determined NADH rapidly increased to a maximum of 4.0%-12.5% above pre-exposure control levels at one-half minute, then decreased slowly to 2% above control at three minutes, finally increasing slowly to 5% above control level at five minutes. ATP and CP assays were performed on sham- and microwave-exposed brain at each exposure time. At 13.8 mW/cm2, brain CP level was decreased an average of 39.4%, 41.1%, 18.2%, 13.1%, and 36.4% of control at exposure points one-half, one, two three, and five minutes, respectively, and brain ATP concentration was decreased an average of 25.2%, 15.2%, 17.8%, 7.4%, and 11.2% of control at the corresponding exposure periods. ATP and CP levels of rat brain exposed to 591-MHz cw microwaves at 5 mW/cm2 for one-half and one minute were decreased significantly below control levels at these exposure times, but were not significantly different from the 13.8 mW/cm2 exposures. For all exposures, rectal temperature remained constant. Heat loss through the skull aperture caused brain temperature to decrease during the five-minute exposures. This decrease was the same in magnitude for experimental and control subjects. Changes in NADH, ATP, and CP levels during microwave exposure cannot be attributed to general tissue hyperthermia. The data support the hypothesis that microwave exposure inhibits mitochondrial electron transport chain function, which results in decreased ATP and CP levels in brain.
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  • 13
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    Bioelectromagnetics 1 (1980) 
    ISSN: 0197-8462
    Keywords: Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
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  • 14
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    Bioelectromagnetics 1 (1980), S. 253-270 
    ISSN: 0197-8462
    Keywords: thermal model ; heat transfer ; dosimetry, 80 MHz ; 200 MHz ; absorption of electromagnetic energy ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The human body was modeled by numerical procedures to determine the thermal response under varied electromagnetic (EM) exposures. The basic approach taken was to modify the heat transfer equations for man in air to account for thermal loading due to the energy absorbed from the EM field. The human body was represented in an EM model by a large number of small cubical cells of tissue, and the energy density was determined for each cell. This information was then analyzed by a thermal response model consisting of a series of two-dimensional transient conduction equations with internal heat generation due to metabolism, internal convective heat transfer due to blood flow, external interaction by convection and radiation, and cooling of the skin by sweating and evaporation. This model simulated the human body by a series of cylindrical segments. The local temperature at 61 discrete locations as well as the thermoregulatory responses of vasodilatation and sweating were computed for a number of EM field intensities and two frequencies, one near whole-body resonance.
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  • 15
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    Bioelectromagnetics 1 (1980), S. 271-275 
    ISSN: 0197-8462
    Keywords: calcium ions ; brain tissue ; radiofrequency (RF) radiation ; complex permittivity (∊r* ; 50 MHz ; 147 MHz ; 450 MHz ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: To explain a carrier frequency dependence reported for radiofrequency (RF)-induced calcium-ion efflux from brain tissue, a chick-brain hemisphere bathed in buffer solution is modeled as a sphere within the uniform field of the incident electromagnetic wave. Calculations on a spherical model show that the average electric-field intensity within the sample remains the same at different carrier frequencies if the incident power density (Pi) is adjusted by an amount that compensates for the change in complex permittivity (∊r*) and the change of wavelength, as a function of carrier frequency. The resulting formula for transforming Pi is seen to follow the pattern of both positive and negative demonstrations of calcium-ion efflux that have been observed at carrier frequencies of 50, 147, and 450 MHz. Indeed, all results obtained at these three frequencies, when related by Pi's that produce the same average electric-field intensity within the sample, are seen to be in agreement; no prediction is contradicted by an experiment.
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  • 16
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    Bioelectromagnetics 1 (1980), S. 299-312 
    ISSN: 0197-8462
    Keywords: ELF electric field ; 60-Hz ; avoidance behavior ; activity ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: In repeated short-term tests (four sessions, each of 45-minute duration), and one longer test (a 23.5-hour session), behavior of rats was evaluated in a long, narrow shuttlebox. One side of the box was exposed to an electric field at various strengths, while a visually identical opposite side was shielded from exposure. In the short-term tests, rats generally remained shielded from electric fields of 90 kV/m and greater during the first session, and maintained this response in subsequent sessions. In the longer test, this same preference response was demonstrated at field strengths of 75 kV/m and greater; however, at 25 and 50 kV/m, rats exhibited a statistically significant preference for the exposed region of the shuttlebox, but only during the light portion of a 12-hour light: 12-hour dark cycle. Exposed animals made more traverses than sham-exposed controls between the two ends of the shuttlebox during the first hour of the test. The experimental data support the hypothesis that the observed behavioral effects are the result of direct interaction of the electric field with the animal, and not the result of secondary factors such as electric shock, corona discharge, audible noise, ozone, or vibration of the experimental apparatus.
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  • 17
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    Bioelectromagnetics 1 (1980), S. 337-343 
    ISSN: 0197-8462
    Keywords: computer model ; temperature distribution ; lossy sphere ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The temperature distribution inside a lossy sphere resulting from the absorption of microwave energy was approximated by successive numerical iterations, of the thermal energy equation. Heat transfer within the sphere by conduction was considered. In the model energy was not dissipated by convection but was contained in the sphere for over 200 seconds. Exposure of a 5-cm sphere to 3,000 MHz at 30 mW/cm2 for 200 seconds was calculated to produce a temperature rise of 0.56°C near the front surface.
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  • 18
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    Bioelectromagnetics 1 (1980), S. 325-336 
    ISSN: 0197-8462
    Keywords: microwave ; dosimetry ; mouse testis ; 2.45 GHz ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: In order to determine the effects of microwave radiation on the testis, it is necessary to express the physical insult in animal studies in a way that can be replicated elsewhere and ultimately used as a basis for extrapolation to man. However, there is conflict  -  especially in chronic experiments  -  between the desire for precise dosimetry and the need to minimise alteration of the normal physiological functions of the animals. The compromise arrangement used in this study was to house the mice singly, in cages with limited food and water, and to irradiate them for up to 30 days (16 h/day) in an anechoic chamber. The only measurements taken routinely were of power density in the positions normally occupied by the cages. In addition, a series of absorption measurements was made in mouse carcasses: Whole-body specific absorption rate (SAR); energy-deposition patterns (determined thermographically); and local SAR in testis (using a miniature electric (E)-field probe). It was concluded that the SAR in testis was considerably less than the whole-body SAR. Exposure for 16 h at 50 mW/cm2 elevated rectal but not testis temperature, thus demonstrating the ability of the conscious mouse to regulate the temperature of its testis.
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  • 19
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    Bioelectromagnetics 1 (1980) 
    ISSN: 0197-8462
    Keywords: Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 20
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    Bioelectromagnetics 1 (1980), S. 345-352 
    ISSN: 0197-8462
    Keywords: electromagnetic pulsed (EMP) fields ; pentobarbital-induced sleeping time ; serum chemistry ; serum triglycerides ; creatine phosphokinase (CPK) ; Dutch rabbits ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Dutch rabbits were acutely exposed to electromagnetic pulsed (EMP) fields (pulse duration 0.4μs, field strengths of 1-2 kV/cm and pulse repetition rates in the range of 10 to 38 Hz) for periods of up to two hours. The dependent variables investigated were pentobarbital-induced sleeping time and serum chemistry (including serum triglycerides, creatine phosphokinase (CPK) isoenzymes, and sodium and potassium). Core temperature measured immediately pre-exposure and postexposure revealed no exposure-related alterations. Over the range of field strengths and pulse durations investigated no consistent, statistically significant alterations were found in the end-points investigated.
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  • 21
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    Bioelectromagnetics 1 (1980), S. 363-377 
    ISSN: 0197-8462
    Keywords: near field ; plane-wave exposure ; electromagnetic energy absorption ; homogeneous tissue slab ; fast Fourier transform ; 2450 MHz ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The exposure of humans to electromagnetic near fields has not been sufficiently emphasized by researchers. We have used the plane-wave-spectrum approach to evaluate the electromagnetic field and determine the energy deposited in a lossy, homogeneous, semi-infinite slab placed in the near field of a source leaking radiation. Values of the fields and absorbed energy in the target are obtained by vector summation of the contributions of all the plane waves into which the prescribed field is decomposed. Use of a fast Fourier transform algorithm contributes to the high efficiency of the computations. The numerical results show that, for field distributions that are nearly constant over a physical extent of at least a free-space wavelength, the energy coupled into the target is approximately equal to that resulting from plane-wave exposure.
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  • 22
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    Bioelectromagnetics 1 (1980), S. 353-361 
    ISSN: 0197-8462
    Keywords: endotoxin ; hypothermia ; rats ; 2450 MHz ; microwaves ; heating ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The parenteral administration of bacterial endotoxin to rats causes a hypothermia that is maximal after approximately 90 minutes. When endotoxin-injected rats were held in a controlled environment at 22°C and 50% relative humidity and exposed for 90 minutes to microwaves (2450 MHz, CW) at 1 mW/cm2, significant increases were observed in body temperature compared with endotoxintreated, sham-irradiated rats. The magnitude of the response was related to power density (10 mW/cm2 〉 5 mW/cm2 〉 1 mW/cm2). Saline-injected rats exposed for 90 minutes at 5 mW/cm2 (specific absorption rate approximately 1.0 mW/g) showed no significant increase in body temperature compared with saline-injected, sham-irradiated rats. The hypothermia induced by endotoxin in rats was also found to be affected by ambient temperature alone. Increases in ambient temperature above 22°C in the absence of microwaves caused a concomitant increase in body temperature. This study reveals that subtle microwave heating is detectable in endotoxin-treated rats that have an impaired thermoregulatory capability. These results indicate that the interpretation of microwave-induced biological effects observed in animals at comparable rates and levels of energy absorption should include a consideration of the thermogenic potential of microwaves.
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  • 23
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    Bioelectromagnetics 1 (1980), S. 379-388 
    ISSN: 0197-8462
    Keywords: near fields ; plane-wave spectrum (PWS) ; energy deposition ; layering resonance ; multilayered slab model ; plane wave ; fast Fourier transform ; 2,450 MHz ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The electromagnetic energy deposited in a semi-infinite slab model consisting of skin, fat, and muscle layers is calculated for both plane-wave and near-field exposures. The plane-wave spectrum (PWS) approach is used to calculate the energy deposited in the model by fields present due to leakage from equipment using electromagnetic energy. This analysis applies to near-field exposures where coupling of the target to the leakage source can be neglected. Calculations were made for 2,450 MHz, at which frequency the layered slab adequately models flat regions of the human body. Resonant absorption due to layering is examined as a function of the skin and fat thicknesses for plane-wave exposure and as a function of the physical extent of the near-field distribution. Calculations show that for fields that are nearly constant over at least a free-space wavelength, the energy deposition (for the skin, fat, and muscle combination that gives resonant absorption) is equal to or less than that resulting from plane-wave exposure, but is appreciably greater than that obtained for a homogeneous muscle slab model.
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  • 24
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    Bioelectromagnetics 1 (1980), S. 389-396 
    ISSN: 0197-8462
    Keywords: microwaves ; nonionizing radiation ; embryogenesis ; enzymes ; cardiac muscle ; 2.45 GHz ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Although exposure to nonionizing electromagnetic radiation has been reported to cause a variety of systemic alterations during embryonic development, there are few reports of the induction of specific physiologic or morphologic changes in the myocardium. This study was designed to examine the effects of microwave radiation on cardiogenesis in Japanese quail embryos exposed during the first eight days of development to 2.45-GHz continuous-wave microwaves at power densities of 5 or 20 mW/cm2. The specific absorption rates were 4.0 and 16.2 mW/g, respectively. The ambient temperature for each exposure was set to maintain the embryonated eggs at 37.5 °C. This did not preclude thermal gradients in the irradiated embryos since microwaves may not be uniformly absorbed. The test exposure levels did not induce changes in either the morphology of the embryonic heart or the ultrastructure of the myocardial cells. Analysis of the enzymatic activities of lactate dehydrogenase, glutamic oxaloacetic transaminase, and creatine phosphokinase failed to reveal any statistically significant differences between the nonexposed controls and those groups exposed to either 5 or 20 mW/cm2. The data indicate that 2.45-GHz microwave radiation at 5 or 20 mW/cm2 has no effect on the measured variables of the Japanese quail myocardium exposed during the first eight days of development.
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  • 25
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    Bioelectromagnetics 1 (1980), S. 429-431 
    ISSN: 0197-8462
    Keywords: Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
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  • 26
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    Bioelectromagnetics 1 (1980), S. 397-404 
    ISSN: 0197-8462
    Keywords: antibody response ; microwaves ; immunology ; 9-GHz pulsed radiation ; infectivity ; mouse ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: A significant increase was observed in the circulating antibody titers of mice exposed to 9-GHz pulsed microwaves at an average power density of 10 mW/ cm2, two hours per day for five days compared with sham-irradiated animals. The mice were previously immunized with type III pneumococcal polysaccharide. Following irradiation, a portion of the immunized animals were challenged with virulent Streptococcus pneumoniae, type III. Ten days after challenge, mortality was essentially the same in the two groups, but during the ten day period, there was a noticeable increase in the survival time of the irradiated animals compared with the sham-irradiated animals, suggesting that the increased circulating antibody response afforded some degree of temporary protection to the animals.
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  • 27
    ISSN: 0197-8462
    Keywords: 2450-MHz radiation ; complement receptors ; endotoxin ; T cells ; genetic control ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: In attempting to evaluate the mechanisms responsible for susceptibility to the inductive increase in splenic complement receptor-positive (CR+) cells following exposure to 2450-MHz microwaves, it was found that sensitivity to microwave-induced CR+cell increases was under genetic control. In particular, evidence was accumulated suggesting that regulation was under the control of a gene or genes closely associated with but outside of the mouse major histocompatibility complex (H-2). All responsive strains of mice tested were of the H-2k haplotype, while mice of the H-2a, H-2b, H-2d and H-2i5 haplotypes were refractory to the microwave-induced increases in CR+ cells. By utilizing certain H-2k strains of mice that were genetically unable to respond to endotoxin, we were able to show that these strains of mice responded to microwaves, but not to endotoxin, by increasing CR+ cells. Microwave-induced increases in CR+cells were not mimicked by the intraperitoneal injection of hydrocortisone. Athymic mice responded to microwave exposure, indicating that this event was not regulated by the T-cell population. Mice less than eight weeks old were found not to be susceptible to exposure to 2450-MHz microwaves. These studies indicate that microwaves do induce changes in the population of cells with specific cell-surface receptors, that susceptibility to these changes is under genetic control, and that it is unlikely that endotoxin, corticosteroids, or regulatory T cells play a significant role in the mechanisms regulating these increases.
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  • 28
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    Bioelectromagnetics 1 (1980), S. 415-428 
    ISSN: 0197-8462
    Keywords: microwave radiation ; pulse-modulated ; operant behavior ; chronic irradiation ; waveguide exposure ; performance ; microwave dosimetry ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: A facility for the exposure of small animals to pulse-modulated microwave radiation (PM MWR) concurrent with their performance of operant behavioral tasks is described. The computer-managed facility comprises an array of 32 individual waveguide exposure cells, each enclosing instrumental conditioning apparatus within a plastic subhousing. The distribution of the microwave electric field intensity within the waveguide was measured by a nonperturbing probe and the modifications induced by the behavioral apparatus and animal within the waveguide determined. Input and interior voltage standing wave ratios are presented to characterize the design of the chambers and to demonstrate the suitability of the chambers for whole-body irradiation of rat. The specific absorption rate (SAR) is presented utilizing data derived from incremental thermometric examination of saline loads and of selected sites in rat carcasses. This is compared with the whole-body SAR derived from the input/ output energy balance equation for the waveguide. The results of continuous monitoring of the SAR by the latter method, while unrestrained rats were engaged in operant and exploratory behavior within the waveguide, are utilized to derive a relationship between chamber input power and the dose rate for adult rats behaviorally active within the waveguide. From these data, we conclude that the experimental array provides a practical method for exposing a large number of animals to PM MWR for long periods of time and coincident with the establishment and/or performance of complex operant behavior.
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  • 29
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    Bioelectromagnetics 1 (1980), S. 21-34 
    ISSN: 0197-8462
    Keywords: radiofrequency radiation ; microwaves ; rhesus monkey dosimetry ; microwave dosimetry ; cranial structures ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Temperature 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, depending on location.
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  • 30
    ISSN: 0197-8462
    Keywords: calcium ions ; brain tissue ; radiofrequency radiation ; amplitude modulation ; power-density window ; nonionizing radiation ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Changes 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 sinewave modulation.
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  • 31
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    Bioelectromagnetics 1 (1980), S. 55-64 
    ISSN: 0197-8462
    Keywords: 60-Hz electric fields ; electrocardiogram (ECG) ; heart rate ; blood pressure ; vascular reactivity ; cold stress ; rats ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Recently, 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 electrodes and animal cages.
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  • 32
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    Bioelectromagnetics 1 (1980), S. 65-76 
    ISSN: 0197-8462
    Keywords: mutagenesis ; reproduction ; rats ; 2,450 MHz ; microwaves ; continuous wave (CW) ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Tests 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 power density.
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  • 33
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    Bioelectromagnetics 1 (1980), S. 77-87 
    ISSN: 0197-8462
    Keywords: mouse spleen lymphocytes ; marrows ; 2,450 MHz ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: A 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/cm2 over 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 radiation.
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  • 34
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    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 1 (1980) 
    ISSN: 0197-8462
    Keywords: Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
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  • 35
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    Bioelectromagnetics 1 (1980), S. 89-99 
    ISSN: 0197-8462
    Keywords: repeated acquisition ; microwave radiation ; lever press ; rats ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The 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/cm2 increased errors and altered the pattern of within-session acquisition. Exposure to the 10 mW/cm2 power density decreased the rate of sequence completion in all animals. The results of exposures at 0.25, 0.5, and 1 mW/cm2 power densities were generally within the control range. The results are interpreted as indicating a disruption in the discriminative stimulus control of the repeated acquisition behavior.
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  • 36
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    Bioelectromagnetics 1 (1980), S. 101-115 
    ISSN: 0197-8462
    Keywords: escape ; microwaves ; rats ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Ocularly pigmented rats, all mature females of the Long-Evans strain, were repeatedly presented an opportunity to escape from an intense 918-MHz field (whole-body dose rate = 60 mW/g) to a field of lower intensity (40, 30, 20, or 2 mW/g) by performing a simple locomotor response. Other rats could escape 800-μA faradic shock to the feet and tail by performing the same response in the same milieu, a multimode cavity. None of 20 irradiated rats learned to associate entry into a visually well-demarcated area of the cavity with immediate reduction of dose rate, in spite of field-induced elevations of body temperature to levels that exceeded 41°C and would have been lethal but for a limit on durations of irradiation. In contrast, all of ten rats motivated by faradic shock rapidly learned to escape. The failure of escape learning by irradiated animals probably arose from deficiencies of motivation and, especially, sensory feedback. Whole-body hyperthermia induced by a multipath field may lack the painful or directional sensory properties that optimally promote the motive to escape. Moreover, a decline of body temperature after an escape-response-contingent reduction of field strength will be relatively slow because of the large thermal time constants of mammalian tissues. Without timely sensory feedback, which is an essential element of negative reinforcement, stimulus-response associability would be imparied, which could retard or preclude learning of an escape response.
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  • 37
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    Bioelectromagnetics 1 (1980), S. 313-323 
    ISSN: 0197-8462
    Keywords: microwave ; blood-brain barrier ; Evans blue ; sodium fluorescein ; brain and body temperatures ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: This investigation was aimed at correlating changes of blood-brain-barrier permeability with the quantity and distribution of absorbed microwave energy inside the brain of adult Wistar rats anesthetized by sodium pentobarbital. Through use of thermographic methods and a direct-contact applicator at the animal's head, the pattern of absorbed microwave energy was determined. Indwelling catheters were placed in the femoral vein and in the left external carotid artery. Evans blue and sodium fluorescein in isotonic saline were used as visual indicators of barrier permeation. Exposure to pulsed 2,450-MHz radiation for 20 min at average power densities of 0.5, 1, 5, 20, 145 or 1,000 mW/cm2, which resulted in average specific absorption rates (SARs) of 0.04, 0.08, 0.4, 1.6, 11.5 or 80.0 mW/g in the brain, did not produce staining, except in the pineal body, the pituitary gland, and the choroid plexus  -  regions that normally are highly permeable. Except for these regions, staining was also absent in the brains of sham-exposed animals. The rectal temperature, as monitored by a copper-constantan thermocouple, showed a maximum increase of less than 0.75°C from a mean pre-exposure temperature of 36.6°C. The highest brain temperature recorded in a similar group of animals using a thickfilm carbon thermistor was less than 41.0°C.
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