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  • Life and Medical Sciences  (45)
  • 1980-1984  (45)
  • 1940-1944
  • 1980  (45)
  • 11
    Electronic Resource
    Electronic Resource
    A thermal model of the human body exposed to an electromagnetic field (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 1 (1980), S. 253-270 
    Details
    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.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250010302
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  • 12
    Electronic Resource
    Electronic Resource
    Calcium-ion efflux from brain tissue: Power-density versus internal field-intensity dependencies at 50-MHz RF radiation (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 1 (1980), S. 277-283 
    Details
    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.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250010304
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  • 13
    Electronic Resource
    Electronic Resource
    Effects of 60-Hz electric fields on avoidance behavior and activity of rats (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 1 (1980), S. 299-312 
    Details
    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.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250010306
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  • 14
    Electronic Resource
    Electronic Resource
    Effects of 2.45-GHz microwave radiation on embryonic quail hearts (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 1 (1980), S. 389-396 
    Details
    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.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250010405
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  • 15
    Electronic Resource
    Electronic Resource
    Induction of calcium-ion efflux from brain tissue by radiofrequency radiation: Effect of sample number and modulation frequency on the power-density window (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 1 (1980), S. 35-43 
    Details
    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.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250010104
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  • 16
    Electronic Resource
    Electronic Resource
    Far-field microwave dosimetry in a rhesus monkey model (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 1 (1980), S. 149-160 
    Details
    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.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250010205
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  • 17
    Electronic Resource
    Electronic Resource
    Millimeter wave absorption spectra of biological samples (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 1 (1980), S. 285-298 
    Details
    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.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250010305
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  • 18
    Electronic Resource
    Electronic Resource
    Dosimetry for a study of effects of 2.45-GHz microwaves on mouse testis (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 1 (1980), S. 325-336 
    Details
    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.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250010308
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  • 19
    Electronic Resource
    Electronic Resource
    Comparison of the coupling of grounded humans, swine and rats to vertical, 60-Hz electric fields (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 1 (1980), S. 117-129 
    Details
    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.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250010203
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  • 20
    Electronic Resource
    Electronic Resource
    Die Vögel Großbritanniens. Von John Gould Hrsg. von Armin Geus. 5 Bände, Broschur m. Leinen kaschiert, in Kassette. 367 Farbtafeln. Die bibliophilen Taschenbücher, Harenberg Kommunikation, Dortmund 1979. Subskriptions-Pr. DM 98, - (später 138, - ) (1980)
    Weinheim : Wiley-Blackwell
    Biologie in unserer Zeit 10 (1980), S. 126-127 
    Details
    ISSN: 0045-205X
    Keywords: Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/biuz.19800100412
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