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  • Occupational Health and Environmental Toxicology  (55)
  • Wiley-Blackwell  (55)
  • American Chemical Society
  • 1980-1984  (55)
  • 1982  (55)
Collection
Keywords
Publisher
  • Wiley-Blackwell  (55)
  • American Chemical Society
Years
  • 1980-1984  (55)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Dielectric probe of the electric-field-sensitive peptide alamethicin (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 3 (1982), S. 25-28 
    Details
    ISSN: 0197-8462
    Keywords: dielectric dispersion ; alamethicin ; dipole moment ; molecular shape ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Dielectric constant and loss of alamethicin in solvents of various degrees of lipophilicity (namely mixtures of n-octanol and dioxane) have been measured at frequencies from 5 kHz to 50 MHz. By means of a conventional Cole-Cole approach, dielectric properties were evaluated to obtain information about the structural and dipolar properties of the peptide in view of its function as a voltage-dependent pore former in membranes. The results for a pure octanol solvent (together with an apparent molecular weight determined by ultracentrifugation) indicate the existence of primarily monomeric particles of quite elongated shape and of comparatively high dipole moment. Adding dioxane was found to yield considerable aggregation and a decrease of polarity.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250030107
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  • 2
    Electronic Resource
    Electronic Resource
    Electromagnetic absorption in an inhomogeneous model of man for realistic exposure conditions (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 3 (1982), S. 81-90 
    Details
    ISSN: 0197-8462
    Keywords: dosimetry ; far-fields/near-fields ; inhomogeneous dielectric properties ; SAR distribution ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The advances made in quantifying electromagnetic absorption and its distribution for various exposure profiles are described. The conditions that have been studied extensively are: free-space irradiation and its variations, such as the presence of ground and reflecting surfaces and other humans in close proximity. Using an inhomogeneous block model of man, work has recently been extended to leakage-type near-fields such as those from RF heat sealers and other electronic equipment. Projections are made for the extension of this work to evaluate coupled near-fields, design of multielement near-field applicators to obtain physician-prescribed uniform or nonuniform rates of regional heating, and for the inverse scattering problem necessary for electromagnetic biomedical imaging. Accurate information about the dielectric properties of various tissues becomes increasingly important for proper inhomogeneous modeling of man.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250030112
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  • 3
    Electronic Resource
    Electronic Resource
    An approach to inverse scattering problems (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 3 (1982), S. 73-80 
    Details
    ISSN: 0197-8462
    Keywords: Born approximation ; Eikonal approximation ; hyperthermia ; inverse problem ; scattering ; imaging ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: There are several reasons for investigating the inverse scattering problem in medical image processing. A typical case, that of ultrasonic fields, is considered. Assuming that a plane wave illuminates a weakly inhomogeneous two-dimensional object, the fundamental equation is derived for the scattered waves in integral as well as in differential forms. It is shown that the scattered waves observed on a circle surrounding the object is sufficient to specify the structure of the object. This information is summarized in a single term, which is a function of the wavenumber as well as the angles of incidence and observation. A successive approximation is applied to reconstruct the image of the object from this function. Since no analytic solution is available, several methods of approximations are proposed, and examples of computations are shown for the case of a cylindrical object.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250030111
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  • 4
    Electronic Resource
    Electronic Resource
    Active electric properties of cardiac muscle (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 3 (1982), S. 127-132 
    Details
    ISSN: 0197-8462
    Keywords: cardiac muscle ; electric properties ; syncytium ; cable theory ; cell membrane ; intracellular potential ; extracellular potential ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: A model of electrical activity in the heart has been developed that treats the intracellular domain and the extracellular domain as electrical syncytia with anisotropic resistivities (bi-syncytial model). At the microscopic level, propagation is assumed to proceed primarily along the axes of individual cells. Considerations at the macroscopic level relate the transmembrane current to the intracellular and extracellular resistivity and the transmembrane potential. The result is a relationship between instantaneous extracellular potentials and cardiac action potentials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250030116
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  • 5
    Electronic Resource
    Electronic Resource
    A comparative study of human sensory thresholds: 2450-MHz Microwaves vs far-infrared radiation (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 3 (1982), S. 117-125 
    Details
    ISSN: 0197-8462
    Keywords: microwaves ; infrared ; human ; thresholds ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Three male and three female adults individually placed the ventral surface of the right and upright forearm against a 15-cm-diameter aperture in a wall of microwave-absorbent material. Tensecond exposures occurred to E-vector-vertically polarized, 2450-MHz-CW microwave (MW) fields. Comparable exposure to infrared (IR) waves was repeated with four of the six observers. Thresholds of detection of just-noticeable warming by MW and IR radiation were determined by the double-staircase psychophysical method. Although the exposed surface areas of male observers' arm were larger than those of female observers, thresholds of warming by either source of energy overlapped; the pooled means of irradiance at threshold are 26.7 mW/cm2 (MW) and 1.7 mW/cm2 (IR). Dosimetric measures on saline models indicated virtually perfect absorption of the incident IR, but nearly two-thirds of the MW energy was scattered. Accordingly, the 15-fold difference in means of MW and IR thresholds resolves to a 5-fold difference in threshold quantities of absorbed energy. In the light of the high correlation between thresholds of IR and MW irradiation (r = .97), it is concluded that the same set of superficial thermoreceptors was being stimulated, only less efficiently so, by the more deeply penetrating, more diffusely absorbed MW energy.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250030115
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  • 6
    Electronic Resource
    Electronic Resource
    Wideband acoustic energy studies of pulmonary airways (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 3 (1982), S. 167-177 
    Details
    ISSN: 0197-8462
    Keywords: impulse response ; pulmonary system ; analog correlator ; cross correlation techniques ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The impulse response of the pulmonary system has been measured by exciting the system with wideband acoustic noise introduced through the mouth. The transmitted sound is detected using microphones placed on the patient's back at appropriate locations. A specially designed analog correlator is used to obtain the impulse response of the pulmonary system through cross-correlation techniques. Uniquely characteristic responses have been obtained from smoking and nonsmoking patient groups.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250030120
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  • 7
    Electronic Resource
    Electronic Resource
    Investigation of the effects of continuous-wave, pulse- and amplitude-modulated microwaves on single excitable cells of chara corallina (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 3 (1982), S. 203-212 
    Details
    ISSN: 0197-8462
    Keywords: S-band microwaves ; modulation ; action potential ; resting potential ; Chara corallina ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Single internodal excitable cells of Chara corallina were exposed to CW, pulse-modulated and sinusoidally modulated S-band microwave fields in a temperature-controled waveguide exposure chamber. All electrical measurements were made external to the waveguide (ie, under no impressed microwave field). The dependent variables measured before, during, and after exposure to the S-band microwave fields included: resting potential, amplitude of the action potential, rise and decay time of the action potential, conduction velocity, and excitability. Cells maintained at 22 ± 0.1 °C during exposure showed no consistent or statistically significant microwave-dependent alterations in any of the dependent variables.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250030204
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  • 8
    Electronic Resource
    Electronic Resource
    Influence of 2.45-GHz CW microwave radiation on spontaneously beating rat atria (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 3 (1982), S. 219-226 
    Details
    ISSN: 0197-8462
    Keywords: microwave radiation ; nonionizing radiation ; atria ; heart rate ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The chronotropic and inotropic effects of 2.45-GHz continuous wave (CW) microwave radiation were investigated in the isolated spontaneously beating rat atria. Isolated atria were placed in specially designed tubes inserted into a waveguide exposure system. The atria were then irradiated for a period of 30 min, followed by a 30-min recovery period. The control atria were prepared simultaneously and sham exposed. Experiments were conducted at two temperatures, 22 and 37 °C, and two specific absorption rates, 2 mW/g and 10 mW/g. At both temperatures the rate of atrial contraction was not altered by a 30-min exposure at either 2 or 10 mW/g. The average rate (beats per min) was approximately 100 for both the control and exposed atria at 22 °C and 215 beats per min for both the control and exposed atria at 37 °C. In addition, no inotropic effects on the spontaneously beating atria were noted at any exposure level. These data suggest that 2.45-GHz CW microwave radiation at these intensities has no overt effect on these variables in isolated rat atria.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250030206
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  • 9
    Electronic Resource
    Electronic Resource
    Comparative effects of pulsed and continuous-wave 2.8-GHz microwaves on temporally defined behavior (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 3 (1982), S. 227-235 
    Details
    ISSN: 0197-8462
    Keywords: microwaves ; pulsed-wave ; continuous-wave ; operant behavior ; DRL schedule ; rats ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The effects of pulsed-(PW) and continuous-wave (CW) 2.8-GHz microwaves were compared on the performance of rodents maintained by a temporally defined schedule of positive reinforcement. The schedule involved food-pellet reinforcement of behavior according to a differential-reinforcement-of-low-rate (DRL) contingency. The rats were independently exposed to PW and to CW fields at power densities ranging from 1 to 15 mW/cm2. Alterations of normal performance were more pronounced after a 30-minute exposure to the PW field than to the CW field. The rate of emission of appropriately timed responses declined after exposure to PW at 10 and 15 mW/cm2, whereas exposure at the same power levels to the CW field did not consistently affect the rate of responding. Change in performance associated with microwave exposure was not necessarily related to a general decline in responding: in some instances, increases in overall rates of responding were observed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250030207
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  • 10
    Electronic Resource
    Electronic Resource
    Near-field absorption in a circular cylinder from electric and magnetic line sources (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 3 (1982), S. 253-274 
    Details
    ISSN: 0197-8462
    Keywords: radiofrequency ; nearfield ; hyperthermia ; dosimetry ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: A homogeneous, lossy circular cylinder is used as a simple model of a biological object in which interior heating is produced by the absorption of electromagnetic waves. For this model, we determined the optimum frequency, polarization, orientation and shape of applicators. Analytical and numerical results are given for both electric and magnetic line sources, with three different polarizations relative to the cylinder. Coupling efficiencies and contour plots are presented for a range of parameters. One particularly interesting result is the production of maximum energy deposition at the center of a cylinder of muscle tissue when exposed in the 100-MHz frequency range by the use of four applicators surrounding the cylinder.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250030210
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