Radio-frequency electromagnetic fields associated with cellular-radio cell-site antennas.

Because of a heightened public awareness of issues pertaining to the use of electromagnetic energy, concurrent with a rapid growth of the cellular telephone industry, a study was initiated to characterize the electromagnetic environment associated with typical cell-site antennas. In particular, the radio-frequency electromagnetic (RF) fields in the vicinity of several antenna towers, ranging in height from 46-82 m, were characterized by measurement. In all cases, the antennas were omnidirectional co-linear arrays. The maximal power densities considered representative of public exposure were found to be less than 100 microW/m2 (10 nW/cm2) per radio channel. Comparison of measured values with the corresponding values that were calculated from the free-space transmission formula indicated that the analytical technique is conservative (i.e., overestimates field levels). The measured and corresponding analytical values were found to be well below accepted exposure limits even when extrapolated to simultaneous and continuous operation of the maximal number of transmitters that would be expected to be installed at a cell-site. Additional measurements were made in the near field of the same antenna type in a roof-mounted configuration. At a distance of 0.7 m from the antenna, the maximal power density in the main beam was found to be less than 30 W/m2 (3 mW/cm2) when normalized to sixteen radio channels (the maximal number used on a single antenna) and less than 30 mW/m2 (3 microW/m2) at 70 m. In all cases, the effective radiated power (ERP) by each radio channel was 100 W referenced to a half-wave dipole. This paper describes the instrumentation and measurement techniques used for this study and provides a summary of the results.     

The properties of liquid water in electric and magnetic fields

A new model of liquid water is proposed, which involves the liquid-crystalline phase, namely, the presence of linearly ordered chains of water molecules and large clusters of these molecules. The presence of linearly ordered chains and clusters in liquid water makes itself evident after the exposure of water to low-frequency electromagnetic radiation. The kinetics of the linearly ordered chains is described by nonlinear excitations (solitons). A hydrodynamic equation describing the behavior of this model system was derived. On the basis of the model, the dimensions of clusters were determined (approximately 600 A). The calculated values of dielectric permeability in the range of low frequencies appeared to be close to their experimentally obtained values. A tenfold increase in the stationary value of dielectric permeability compared with the known value of the dielectric constant in the frequency range of 10(4)-10(6) Hz was predicted. The frequency dependence of dielectric permeability in this range was studied.     

The optical properties of Li- and Na-DNA films

We have measured the refractive indices of highly crystalline Li- and Na-DNA wet-spun films as a function of their water content using an immersion technique. We calculated the molecular polarizabilities of a DNA base pair using the Lorentz–Lorenz relation for anisotropic materials, the measured water contents, and densities corrected for void formation. For Li-DNA, the polarizabilities are independent of the relative humidity, whereas for Na-DNA, there are large changes at the A-B transition and also at low humidities. The average polarizability of A-Na-DNA is in agreement with that calculated from refractive index increments and also as calculated by a simple addition of bond polarizabilities, whereas the values for Li- and B-Na-DNA are about 30% larger than the calculated values. We propose that these anomalous values are due to nonlinear polarizabilities of the phosphate group.     

Short-circuit currents,surface electric fields,and axial current densities for guinea pigs exposed to ELF electric fields.

Short-circuit currents, surface electric fields, and axial current densities were measured in electrically grounded guinea pigs exposed to a uniform, vertical, ELF electric field. These data are 70–110% of corresponding values obtained in grounded rats exposed to the same electric field.     

A three-dimensional method for calculating currents induced in bodies by extremely low-frequency electric fields

A user-friendly, numerical program has been developed to permit the calculation of induced currents in modeled bodies of human and infrahuman subjects. The program is based on a charge-simulation method (CSM), and it takes into account the three-dimensional (3-D) character of the extremely-low-frequency (ELF) electric field and of the models to be exposed. The principle of the method is to simulate a 3-D object, for example, an animal model, by a combination of several parts (blocks) having simple geometric forms such as a sphere, a cylinder, or a cone. This approach permits easy preparation of input data on the dimensions of the blocks and their positions in a 3-D arrangement. Other input data, such as the coordinates of the contour points and the imaginary values of charges inside objects, which are necessary in the calculations by CSM, are produced automatically by selecting an appropriate "level" for each block, according to its importance. To simulate parts having irregular shapes, special blocks may be added. In one series of experiments, induced currents were calculated for a baboon model in various postures: standing upright, positioned on four legs, and sitting on the floor. Calculated currents, the total induced current in particular, agreed very well with experimental values. Local currents in parts of the baboon models were more variable, ranging from 5% to 17% of measured values in the case of induced currents in the head. Some problems with this method, such as the effect of the dimensions of blocks or the choice of block levels, are discussed.     

Occupational exposure to electric fields and currents associated with 110 kV substation tasks

The main aim of this study was to investigate occupational exposure to electric fields, and current densities and contact currents associated with tasks at air-insulated 110 kV substations and analyze if the action value of EU Directive 2004/40/EC was exceeded. Four workers volunteered to simulate the following tasks: Task (A) maintenance of an operating device of a disconnector at ground or floor level, Task (B) maintenance of an operating device of a circuit breaker at ground or floor level, Task (C) breaker head maintenance from a man hoist, and Task (D) maintenance of an operating device of a circuit breaker from a service platform. The highest maximum average current density in the neck was 1.8 mA/m(2) (calculated internal electric field 9.0-18.0 mV/m) and the highest contact current was 79.4 μA. All measured values at substations were lower than the limit value (10 mA/m(2)) of the EU Directive 2004/40/EC and the 2010 basic restrictions (0.1 and 0.8 V/m for central nervous system tissues of the head, and all tissues of the head and body, respectively) of the International Commission on Non-Ionizing Radiation Protection (ICNIRP).     

Wire codes,magnetic fields,and childhood cancer

Childhood cancer has been modestly associated with wire codes, an exposure surrogate for power frequency magnetic fields, but less consistently with measured fields. We analyzed data on the population distribution of wire codes and their relationship with several measured magnetic field metrics. In a given geographic area, there is a marked trend for decreased prevalence from low to high wire code categories, but there are differences between areas. For average measured fields, there is a positive relationship between the mean of the distributions and wire codes but a large overlap among the categories. Better discrimination is obtained for the extremes of the measurement values when comparing the highest and the lowest wire code categories. Instability of measurements, intermittent fields, or other exposure conditions do not appear to provide a viable explanation for the difference between wire codes and magnetic fields with respect to the strength and consistency of their respective association with childhood cancer. Bioelectromagnetics 18:99–110, 1997. © 1997 Wiley-Liss, Inc.     

Temperature and configurational effects on the Young’s modulus of poly (methyl methacrylate): a molecular dynamics study comparing the DREIDING,AMBER and OPLS force fields

The effects of the configuration and temperature on the Young’s modulus of poly (methyl methacrylate) (PMMA) have been studied using molecular dynamics simulations. For the DREIDING force field under ambient temperatures, increasing the number of monomers significantly increases the modulus of isotactic and syndiotactic PMMA while the isotactic form has a greater modulus. The effects of temperature on the modulus of isotactic PMMA have been simulated using the DREIDING, AMBER, and OPLS force fields. All these force fields predict the effects of temperature on the modulus from 200 to 350 K that are in close agreement with experimental values, while at higher temperatures the moduli are greater than those measured. The glass transition temperature determined by the force fields, based on the variation of the modulus with temperature, is greater than the experimental values, but when obtained from a plot of the volume as a function of the temperature, there is closer agreement. The Young’s moduli calculated in this study are in closer agreement to the experimental data than those reported by previous simulations.     

Body surface area of the golden Syrian hamster.

The body surface areas (BSAs) of 30 Syrian hamsters were actually measured. From these areas, the Mass Coefficients (K values) for the Dubois and Dubois equation (5.31) and for the Meeh-Rubner equation (11.89), were computed. These values were independent of weight and sex. To verify the applicability of the Mass Coefficients, the BSAs of another 20 animals were calculated and compared with the actually measured BSAs. The difference between measured and calculated BSAs was not significant. Therefore, these values can be used with their respective equations to compute BSA in Golden Syrian hamsters.     

The interaction of extravascular pressure fields and fluid exchange in capillary networks

A previously developed model [4] is extended to include capillary networks of realistic three-dimensional architecture, and used to examine the interaction of the local tissue pressure field with fluid exchange. Fluid-flux calculations using this model show that interaction, which reduces the predicted amount of fluid exchanged below that predicted by the classical Starling's hypothesis, increases with increasing numbers of capillary segments. Fluid filtration from one capillary is affected by the local pressure fields of other capillaries, resulting in a capillary-capillary interaction. This interaction increases with increasing values of the ratio of endothelial to tissue hydraulic conductivities. For large values of the ratio, the model predicts a fluid flux almost 90% less than that calculated by Starling's hypothesis. It is shown, however, that at even the smallest physiologically reasonable value of this ratio, interaction still has a significant effect in reducing the predicted fluid exchange in large networks.     

60-Hz electric and magnetic fields generated by a distribution network

From a mobile unit, 60-Hz electric and magnetic fields generated by Hydro-Québec's distribution network were measured. Nine runs, representative of various human environments, were investigated. Typical values were 32 V/m and 0.16 microT. The electrical distribution networks investigated were major contributors to the electric and magnetic environments.     

Determination of cardiac output and other reference physiology parameters in lightly anesthetized dogs

1. Cardiac output; arterial, pulmonary artery, central venous and pulmonary wedge pressures; heart rate, hematocrit, and plasma sodium and potassium; arterial and mixed venous blood gases; and respiratory rates were measured in 45 mixed sex, non-pregnant, clinically normal mongrel dogs of 8-30 kilograms body weight following light anesthesia with halothane/50% N20-02. 2. Arithmetic means and standard deviations were calculated to develop tables of reference values. 3. Mean measured cardiac outputs were found to be 31-59% higher in these dogs than the values indicated by published standards; cardiac indices were 30-44% higher; heart rates were 16-30% lower; calculated stroke volumes were 60-112% greater; and total peripheral resistances were 35-57% less than the standard published values. 4. All other measured or calculated parameters fell within previously published canine or human reference limits.     

The paradox between m values and deltaCp's for denaturation of ribonuclease T1 with disulfide bonds intact and broken.

Urea-induced denaturations of RNase T1 and reduced and carboxyamidated RNase T1 (RTCAM) as a function of temperature were analyzed using the linear extrapolation method, and denaturation m values, deltaCp, deltaH, deltaS, and deltaG quantities were determined. Because both deltaCp and m values are believed to reflect the protein surface area newly exposed on denaturation, the prediction is that the ratio of m values for RNase T1 and RTCAM should equal the deltaCp ratio for the two proteins. This is not the case, for it is found that the m value of RTCAM is 1.5 times that of RNase T1, while the denaturation deltaCp's for the two proteins are identical. The paradox of why the two parameters, m and deltaCp, are not equivalent in their behavior is of importance in the interpretations of their respective molecular-level meanings. It is found that the measured denaturation deltaCp's are consistent with deltaCp's calculated on the basis of empirical relationships between the change in surface area on denaturation (deltaASA), and that the measured m value of RNase T1 agrees with m calculated from empirical data relating m to deltaASA. However, the measured m of RTCAM is so much out of line with its calculated m as to call into question the validity of always equating m with surface area newly exposed on denaturation.     

Effects of extremely low-frequency magnetic fields on L-glutamic acid aqueous solutions at 20, 40, and 60 microT static magnetic fields

Current peaks have been observed and measured in electrolytic ionic current of L-glutamic acid aqueous solutions at room temperature, in static magnetic fields of 20, 40, and 60 muT flux densities, with a superimposed extremely low-frequency, (1/10) Hz, alternating magnetic field flux density of 40 nT. The distributions of the peaks have mean values centered at the cyclotron resonance frequency of the singly charged L-glutamic acid ion molecular mass in the corresponding static field. Amplitudes and widths of the peaks are compared and analyzed to extract their correlation. The results can be considered a contribution to the understanding of the experimental phenomenology in low-frequency electromagnetic fields on ionic currents of L-glutamic amino acid aqueous solutions. The results can be of interest in the studies on the interaction of the electromagnetic fields with some structural neurotransmitters in cellular medium.     

Determination of Antioxidant Activity of Various Bioantioxidants and Their Mixtures by the Amperometric Method

To date, simple and operative electrochemical methods are widely used to study antioxidant properties of various biological objects. One of them is the amperometric method, which is used in various fields of science, technology and medicine to determine the antioxidant activity (AOA) of various beverages, extracts and biological fluids, as well as the total content of antioxidants (AOs) present in them. Measurements of AOA (electrochemical oxidability) of some known individual AO and their mixtures by the amperometric method was performed in the present work. The coefficients of their oxidability were determined. The AOA values obtained correlate well with the AOA of these compounds measured by other methods. The coincidence of the experimental values of AOA and the values calculated with the use of the coefficients of oxidability for each component of the mixture was observed for most combinations of binary mixtures of used AOs. This indicates the absence of interaction between them (synergism or antagonism) during the oxidation. Several mixtures with a lower value of the measured AOA compared with the calculated value (antagonism) represented the exception. During the electrochemical oxidation of the “oxidized glutathione + ascorbic acid” mixture, partial reduction of glutathione by ascorbic acid is likely to proceed, which results in an excess of the measured AOA value over the calculated value. The results obtained may be useful when working with devices based on the amperometric method.     

Energy balance of an isolated scots pine

The transpiration of an isolated Scots pine (P. sylvestris), determined by weighing, was related to stomatal resistance and environmental factors. The tree had been sheared to 1.5 m diameter at the base and 1.8 m high. The transpiration (2.97 MJ for 12h) was rather constant throughout the day and similar in shape to direct beam radiation incident upon the side of a cone. Transpiration rates calculated with the gradient equation duplicated measured values when vapor density gradients (obtained from measured needle temperature), measured stomatal resistance, and characteristic width of 3 mm in aerodynamic resistance were used in the calculations. Net radiation (Q*) for the tree was calculated by replacing the direct beam component of measured net radiation with the direct beam component incident upon a cone. The sensible heat flux, calculated with needle temperatures, was large (50.8 MJ) and nearly equal to Q* (53.85). The resulting Bowen ratio was 17. Transpiration calculated with a modified Penman-Monteith type equation simulated measured values.Presented at the Eighth International Congress of Biometeorology, 9–14 September 1979, Shefayim, Israel.     

Dual permeability soil water dynamics and water uptake by roots in irrigated potato fields

Water movement and uptake by roots in a drip-irrigated potato field was studied by combining field experiments, outputs of numerical simulations and summary results of an EU project (www.fertorganic.org). Detailed measurements of soil suction and weather conditions in the Bohemo-Moravian highland made it possible to derive improved estimates of some parameters for the dual permeability model S1D_DUAL. A reasonably good agreement between the measured and the estimated soil hydraulic properties was obtained. The measured root zone depths were near to those obtained by inverse simulation with S1D _DUAL and to a boundary curve approximation. The measured and S1D _DUAL-simulated soil water pressure heads were comparable with those achieved by simulations with the Daisy model. During dry spells, the measured pressure heads tended to be higher than the simulated ones. In general, the former oscillated between the simulated values for soil matrix and those for the preferential flow (PF) domain. Irrigation facilitated deep seepage after rain events. We conclude that several parallel soil moisture sensors are needed for adequate irrigation control. The sensors cannot detect the time when the irrigation should be stopped. Presented at the International Conference on Bioclimatology and Natural Hazards, Poľana nad Detvou, Slovakia, 17–20 September 2007.     

Transmembrane voltage induced on altered erythrocyte shapes exposed to RF fields

In this article, the transmembrane voltage induced on erythrocyte, codocyte, ovalocyte and spherocyte cell models exposed to a linearly polarised electromagnetic plane wave of frequency 1800 MHz is calculated. For this purpose, a finite element (FE) numerical technique with adaptive meshing is used. The results show that the value of the induced voltage on the original erythrocyte shape is higher than the one observed on the rest of the altered cell geometries studied. The erythrocyte shape and the membrane electric permittivity are shown to play a fundamental role on the values of the induced transmembrane voltage.     

Dioptrics of the facet lenses of male blowflies Calliphora and Chrysomyia

1. The dioptrics of the facet lenses of two blowfly species, Calliphora erythrocephala and Chrysomyia megacephala, was investigated. Measurements were performed on facet lenses ranging in diameter from 20 to 80 microns. 2. The radius of curvature of the front surface of the facet lenses, measured by microreflectometry, increases approximately linearly with the facet lens diameter. 3. The optical path difference of the facet lens and water, measured by interference microscopy, depends on the distance from the optical axis according to a parabolic function. Average refractive index values, calculated from the optical path difference profile together with estimates of the thickness profile, are between 1.40 and 1.43, with the lowest values in the largest lenses. 4. The F-number calculated from the experimental data ranges from 1.5 to 2.2. It is argued that the range of effective F-numbers is 2.1-2.4.