bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laboratory investigations of the electrical characteristics of honey bees and their exposure to intense electric fields
Authors: Bindokas Vytautas P. , Gauger James R. , Greenberg Bernard 
Published: February 2006

AbstractBees exposed to 60‐Hz electric (E) fields > 150 kV/m show field‐induced vibrations of wings, antennae, and body hairs. They also show altered behavior if exposed while in contact with a conductive substrate. Measurements indicate that approximately 240 nA is coupled to a bee standing on a conductive substrate in a 100‐kV/m E field. In lab experiments, bee disturbance and sting result from exposure to E field >200 kV/m (bee current >480 nA) and reduced voluntary movements at >300 kV/m (>720 nA bee current) only if the bee is on a conductive substrate. It is hypothesized that in the latter situation coupled bee current drains through the lower thorax and legs to the conductive substrate, and that the resulting enhanced current density in these regions is the cause of observed responses. The observation that bees exposed to intense E fields on an insulator show vibration of body parts but no behavioral response suggests that vibration contributes little to the disturbance of bees in intense E fields.Lab measurements of bee impedance from front‐to‐rear leg pairs were made on wet and dry conductors. Measurements validate the selection of 1 MΩ as a middle value for bee impedance used in the design of devices used to generate step‐potential‐induced currents in bees.
Use of wiring configuration and wiring codes for estimating externally generated electric and magnetic fields
Authors: Barnes Frank , Wachtel Howard , Savitz David , Fuller Jackson 
Published: February 2006

AbstractThe relative locations and characteristics of the distribution lines feeding 434 residences in the Denver metropolitan area were recorded and classified according to the Wertheimer‐Leeper code (WL code) as a part of an epidemiological study of the incidence of childhood cancer. The WL code was found to place the mean values of the fields in rank order. However, the standard deviations were approximately the same size as the means. Theoretical calculations indicate that a significant fraction of the low‐power magnetic fields can be generated by the distribution lines, especially in the cases where the distribution lines are within 50 feet of the residence. Thus, the wiring code was shown to be a useful method for making a first‐order approximation to predict long‐term, low‐level magnetic fields in residences.
Relationship between local temperature and heat transfer through the hand and wrist
Authors: Sienkiewicz Z. J. , O'Hagan J. B. , Muirhead C. R. , Pearson A. J. 
Published: February 2006

AbstractThe heat uptake that resulted from immersing the hand and wrist into a water‐filled calorimeter maintained at temperatures between 37–40 °C was measured under standard conditions in a group of eight subjects of either sex. The rate of heat transfer (W) increased exponentially with temperature and was a function of hand or body size and age, but not sex. The heat transfer rate normalized to hand mass (W.kg−1) was determined by temperature and age: best‐fit mean values (and 95% confidence limits of the population) were 6.0 W.kg−1(3.2–11.2 W.kg−1) at an immersion temperature of 37 °C and 25.4 W.kg−1(13.7–47.0 W.kg−1) at 40 °C. The application of these results to limits on specific energy absorption rate induced in the hands and wrists by radiofrequency dielectric heat sealer welders is discussed.
Outdoor measurement of SAR in a full‐sized human model exposed to 29.9 MHz in the near field
Authors: Olsen Richard G. , Griner Toby A. 
Published: February 2006

AbstractLocalized and averaged specific absorption rates (SARs) were obtained in a full‐size muscle‐equivalent human model exposed to near‐field 29.9 MHz irradiation at an outdoor facility. The model was positioned erect on a metallic groundplane 1.22 m (4 ft) from the base of a 10.8‐m (35 ft) whip antenna with an input power of 1.0 kW. For whole‐body SAR, a mean value of 0.83 W/kg was determined using two gradient‐layer calorimeters in a twin‐well configuration. The localized SARs at 12 body locations were measured using nonperturbing temperature probes and were highest in the ankle region. We conclude that averaged SAR measurements in a full‐size phantom are feasible using a twin‐calorimeter approach; measurements in the field are practical when human‐size (183 × 61 × 46 cm) calorimeters are used.
Magnetite biomineralization and geomagnetic sensitivity in higher animals: An update and recommendations for future study
Authors: Kirschvink Joseph L. 
Published: February 2006

AbstractMagnetite, the only known biogenic material with ferromagnetic properties, has been identified as a biochemical precipitate in three of the five kingdoms of living organisms, with a fossil record that now extends back nearly 2 billion years. In the magnetotactic bacteria, protoctists, and fish, single‐domain crystals of magnetite are arranged in membrane‐bound linear structures called magnetosomes, which function as biological bar magnets. Magnetosomes in all three of these groups bear an overall structural similarity to each other, which includes alignment of the individual crystallographic [111] directions parallel to the long axis. Although the magnetosomes represent only a small volume fraction in higher organisms, enough of these highly energetic structures are present to provide sensitivity to extremely small fluctuations and gradients in the background geomagnetic field. Previous experiments with elasmobranch fish are reexamined to test the hypothesis that gradients played a role in their successful geomagnetic conditioning, and a variety of four‐turn coil designs are considered that could be used to test the various hypotheses proposed for them.
Chronic exposure of primates to 60‐Hz electric and magnetic fields: III. Neurophysiologic effects
Authors: Dowman Robert , Wolpaw Jonathan R. , Seegal Richard F. , Satya‐Murti Saty 
Published: February 2006

AbstractThe neurophysiologic effects of combined 60‐Hz electric (E) and magnetic (B) fields, of magnitudes comparable to those produced by high‐voltage powerlines, were investigated in 10 monkeys (Macaca nemestrina). Six animals (experimental group) were each exposed to three different levels of E and B fields: 3 kV/m and 0.1 G, 10 kV/m and 0.3 G, and 30 kV/m and 0.9 G. Field exposures were preceded and followed by sham exposures, during which factors of field generation were present (e.g., heat, vibration, noise, etc.) without E and B fields. Each of the five segments (i.e., the three exposure segments and the initial and final sham exposure segments) lasted 3 weeks. Animals were exposed for 18 h/day (fields on at 1600 h, off at 1000 h). Four other animals (external control group) were given sham exposure for the entire 15‐week period. Auditory, visual, and somatosensory evoked potentials were recorded twice a week, during the daily 6‐h field‐off period.E‐ and B‐field exposure had no effect on the early or mid‐latency evoked potential components, suggesting that exposure at these levels has no effect on peripheral or central sensory afferent pathways. However, there was a statistically significant decrease in the amplitudes of late components of the somatosensory evoked potential during the 10kV/m and 0.3 G, and 30 kV/m and 0.9 G exposure levels. This result is possibly related to the opiate antagonist effect of electromagnetic field exposure reported by others.
Detection‐threshold of 50‐Hz electric fields by human subjects
Authors: Kato M. , Ohta S. , Shimizu K. , Tsuchida Y. , Matsumoto G. 
Published: February 2006

AbstractThe threshold intensity for detection of an AC electric field was studied in human subjects at several different temperatures and humidities. The dorsum and palm of the hand were exposed to fields, representing hairy and hairless skin, in order to clarify whether hair movement is critical for field detection. Experiments were carried out on human subjects (seven men and four women) during hot humid weather of July–August and dry cool air of October–November. Threshold values obtained in the summer were 30–65 kV/m for the hairy skin on the dorsum of the hand, while for the hairless skin on the palm the threshold was > 115 kV/m (highest field available due to limitations of the power supply). During the fall, the threshold was much higher than during the summer. We sought possible reasons for the difference and found that humidity was the main factor. Relative permittivity of woman's hair was then estimated by measuring capacitance of the hairs under dry (35% RH) and wet (85% RH) conditions at 20 °C. The values of relative permittivity obtained under these two conditions differed by several times the average. The differences in detection thresholds may be attributable to the different relative permittivities of the hairs under dry and wet conditions.
Lack of effects from 2000‐Hz magnetic fields on mammary adenocarcinoma and reproductive hormones in rats
Authors: Baumann Stephen , Cooper Ralph , Berman Ezra , House Dennis , Joines William 
Published: February 2006

AbstractFemale rats were implanted with mammary adenocarcinoma tissue and 25 days later exposed to 2,000‐Hz magnetic fields 1 h a day for 9 days. Analysis showed that tumor weights and the levels of several reproductive hormones were not significantly different between treated and control animals. Other studies with a similar design have also reported no significant effects from magnetic field exposure. However, vaginal smear data from all animals revealed that handling and restraint stress may have confounded the detection of subtle magnetic field effects.
Rats reproduce and rear litters during chronic exposure to 150‐kV/m, 60‐Hz electric fields
Authors: Rommereim D. N. , Kaune W. T. , Anderson L. E. , Sikov M. R. 
Published: February 2006

AbstractMature female rats and their subsequent litters were exposed either to 112‐ or to 150‐kV/m, 60‐Hz electric fields or sham‐exposed for 19 h daily through pre‐breeding, breeding, and rearing periods of experimentation. Exposed females mated in equal percentages and reared litters of equal numbers, and mean body masses of pups were the same as those of sham‐exposed animals. Thus, experiments to investigate electric‐field effects on reproduction and development in rats are feasible at effective field strengths of 112 and 150 k V/m.
In vitro lymphocyte proliferation induced by radio‐frequency electromagnetic radiation under isothermal conditions
Authors: Cleary Stephen F. , Liu Li‐Ming , Merchant Randall E. 
Published: February 2006

AbstractWhole human blood was exposed or sham‐exposed in vitro for 2 h to 27 or 2,450 MHz radio‐frequency electromagnetic (RF) radiation under isothermal conditions (i.e., 37 ± 0.2 °C). Immediately after exposure, mononuclear cells were separated from blood by Ficoll density‐gradient centrifugation and cultured for 3 days at 37°C with or without mitogenic stimulation by phytohemagglutinin (PHA). Lymphocyte proliferation was assayed at the end of the culture period by 6 h of pulse labeling with 3H‐thymidine 3H‐TdR). Exposure to radiation at either frequency at specific absorption rates (SARs) below 50 W/kg resulted in a dose‐dependent, statistically significant increase of 3H‐TdR uptake in PHA‐activated or unstimulated lymphocytes. Exposure at 50 W/kg or higher suppressed 3H‐TdR uptake relative to that of sham‐exposed cells. There were no detectable effects of RF radiation on lymphocyte morphology or viability. Notwithstanding the characteristic temperature dependence of lymphocyte activation in vitro, the isothermal exposure conditions of this study warrant the conclusion that the biphasic, dose‐dependent effects of the radiation on lymphocyte proliferation were not dependent on heating.
Magnetic resonance imaging: Calculation of rates of energy absorption by a human‐torso model
Authors: Grandolfo Martino , Vecchia Paolo , Gandhi Om P. 
Published: February 2006

AbstractThe three‐dimensional impedance method was used to estimate specific absorption rate (SAR) in a human‐torso model during exposure to the time‐varying and static magnetic fields used in magnetic resonance imaging (MRI). Analytical data for discrete tissues as well as the entire torso are presented. Generalized equations were derived that enable calculation of whole‐torso SAR over a broad range of conditions. In addition, the impedance method can generate data about internal distributions of SAR, which are needed to predict critical organs that might undergo excessive elevations of temperature. Fair to good agreement was found between impedance‐method SAR and those predicted by simple phenomenological models.
Proflavin and microwave radiation: Absence of a mutagenic interaction
Authors: Meltz Martin L. , Eagan Phyllis , Erwin David N. 
Published: February 2006

AbstractThe potential ability of radiofrequency electromagnetic radiation (RFR) in the microwave range to induce mutagenesis, chromosomal aberrations, and sister chromatid exchanges in mammalian cells is being explored in our laboratories. In addition, we have also been examining the ability of simultaneous exposure to RFR and chemical mutagens to alter the genotoxic damage induced by chemical mutagens acting alone. We have performed experiments to determine whether there is an interaction between 2.45‐GHz, pulsed‐wave, RFR and proflavin, a DNA‐intercalating drug. The endpoint studied was forward mutation at the thymidine kinase locus in L5178Y mouse leukemic cells. Any effect on the size distribution of the resulting colonies of mutated cells was also examined. The exposures were performed at net forward powers of 500 or 600 W, resulting in a specific absorption rate (SAR) of ∼40 W/kg. The culture‐medium temperature reached a 3°C maximal increase during the 4‐h exposure; appropriate 37°C and convection‐heating temperature controls (TC) were performed. In no case was there any indication of a statistically significant increase in the induced mutant frequency due to the simultaneous exposure to RFR and proflavin, as compared with the proflavin exposures alone. There was also no indication of any change in the colony‐size distribution of the resulting mutant colonies, neither, and there was no evidence in these experiments of any mutagenic action by the RFR exposure alone.
Importance of alignment between local DC magnetic field and an oscillating magnetic field in responses of brain tissue in vitro and in vivo
Authors: Blackman C. F. , Benane S. G. , House D. E. , Elliott D. J. 
Published: February 2006

AbstractThe frequency dependence of the electric and magnetic (EM)‐field‐induced release of calcium ions from an in vitro brain tissue preparation has been shown to be a function of the density of the local DC magnetic field (BdC). In this study, we demonstrate that the relative orientation of the Bdc and the magnetic component (Bac) of a 315‐Hz EM signal (15 Vrms/m and 61 nTrms) are crucial for the induced release to be observed. The induced release occurs only when the Bdc and the Bac are perpendicular, and not when they are parallel. This finding is consistent with a magnetic resonance‐like transduction mechanism for the conversion of EM energy into a physicochemical change, and contrasts with the requirement for parallel Bdc and Bac components in the diatom‐mobility experiments of Smith et al. A review of the exposure conditions in the rat behavioral experiments conducted by Thomas et al. identifies unhydrated calcium and zinc ions as alternatives to lithium ions as candidates for interaction under parallel magnetic‐field orientations but fails to reject perpendicular orientations as an alternative basis for the phenomenon. Investigators that attempt to confirm the rat behavioral experiments should be aware of the conflicting exposure conditions that can be assumed to be operative, and they should design their experiments to test all conditions accordingly.
Electric fields and surface charges induced by ELF magnetic fields
Authors: Polk Charles 
Published: February 2006

AbstractA method is described for evaluating electric fields induced by ELF magnetic fields into electrically inhomogeneous, low‐conductivity (<5 S/m) structures. It is applied to cylinders and spheres, and numerical results are given for electrical properties that are representative of some tissues, or of cells embedded either in saline solution or a tissue matrix. Surface currents on spherical cell boundaries are estimated and compared with thermal noise due to ion motion.
On the cyclotron resonance model of ion transport
Authors: Sandweiss Jack 
Published: February 2006

AbstractThe cyclotron‐resonance model, which has been suggested as an explanation of a purported enhancement of transport of ions through the membranes of cells exposed to weak, lowfrequency‐modulated RF fields, is shown to be inconsistent with basic physical principles. Under the conditions of the model, in which the ions are presumed to circulate under the constraint of the earth's magnetic field, the radii of gyration of the ions would approximate 50 m and, thus, are much larger than the cells. Moreover, from general considerations, the collision‐damping time of such ions is expected to be less than 10−10 s, much smaller than the times of the order of 10−2 s, shown to be necessary if the conditions for low‐frequency resonance are to be satisfied.
Use of a spread sheet to calculate the current‐density distribution produced in human and rat models by low‐frequency electric fields
Authors: Hart Francis X. 
Published: February 2006

AbstractThe current‐density distribution produced inside irregularly shaped, homogeneous human and rat models by low‐frequency electric fields is obtained by a two‐stage finite‐difference procedure. In the first stage the model is assumed to be equipotential. Laplace's equation is solved by iteration in the external region to obtain the capacitive‐current densities at the model's surface elements. These values then provide the boundary conditions for the second‐stage relaxation solution, which yields the internal current‐density distribution. Calculations were performed with the Excel spread‐sheet program on a Macintosh‐II microcomputer. A spread sheet is a two‐dimensional array of cells. Each cell of the sheet can represent a square element of space. Equations relating the values of the cells can represent the relationships between the potentials in the corresponding spatial elements. Extension to three dimensions is readily made. Good agreement was obtained with current densities measured on human models with both, one, or no legs grounded and on rat models in four different grounding configurations. The results also compared well with predictions of more sophisticated numerical analyses. Spread sheets can provide an inexpensive and relatively simple means to perform good, approximate dosimetric calculations on irregularly shaped objects.
Electric fields induced by low frequency magnetic fields in inhomogeneous biological structures that are surrounded by an electric insulator
Authors: Polk C. , Song J. H. 
Published: February 2006

AbstractElectric fields induced by low‐frequency magnetic fields into inhomogeneous structures, which have electric conductivities and dielectric permittivities of typical biological substances, are evaluated. Closed‐form approximate and numerical solutions are obtained for nonconcentric cylinders with different electric properties (such as bone embedded in muscle), which are surrounded by a good electrical insulator (such as air). It is shown that even a single inhomogeneity in an otherwise homogenous cylinder, which is exposed to a uniform, axially directed magnetic field, can lead to substantial deviations from the direction and distribution of the induced electric field that would exist in the homogenous cylinder. Thus the induced field is not everywhere circumferential, nor does its magnitude at all angular positions increase linearly with the radial distance. Radially and circumferentially directed field components depend on size, electrical properties, and eccentricity of the inhomogeneities. Equations as well as graphical presentations are given that describe the induced fields when the enclosed inhomogeneities consist either of eccentrically located single cylinders or pairs of coaxial cylinders with different electrical conductivities or dielectric permittivities.
Exposure of frog hearts to CW or amplitude‐modulated VHF fields: Selective efflux of calcium ions at 16 Hz
Authors: Schwartz Jean‐Louis , House Dennis E. , Mealing Geoffrey A. R. 
Published: February 2006

AbstractIsolated frog hearts were exposed for 30‐min periods in a Crawford cell to a 240‐MHz electromagnetic field, either continuous‐wave or sinusoidally modulated at 0.5 or 16 Hz. Radiolabeled with calcium (45Ca), the hearts were observed for movement of Ca2+ at calculated SARs of 0.15, 0.24, 0.30, 0.36, 1.50, or 3.00 mW/kg. Neither CW radiation nor radiation at 0.5 Hz, which is close to the beating frequency of the frog's heart, affected movement of calcium ions. When the VHF field was modulated at 16 Hz, a field‐intensity‐dependent change in the efflux of calcium ions was observed. Relative to control values, ionic effluxes increased by about 18% at 0.3 mW/kg (P <.01) and by 21% at 0.15 mW/kg (P <.05), but movement of ions did not change significantly at other rates of energy deposition. These data indicate that the intact myocardium of the frog, akin to brain tissue of neonatal chicken, exhibits movement of calcium ions in response to a weak VHF field that is modulated at 16 Hz.
Evaluation of changes in diatom mobility after exposure to 16‐Hz electromagnetic fields
Authors: Reese J. A. , Frazier M. E. , Morris J. E. , Buschbom R. L. , Miller D. L. 
Published: February 2006

AbstractThe effect of a 16‐Hz electromagnetic field on the mobility of the diatom Amphora coffeaformis was examined on agar plates that contained no added calcium and also on agar plates containing 0.25 or 2.5 mM exogenous Ca2+. Exposure conditions consisted of an ac field of 16 Hz with an amplitude of 20.9 μT parallel to the horizontal component of the dc field (BH = 20.9 μT, where Bv = 0). To assess results, the percentage of diatoms that moved a distance greater than their body length was determined. We observed the field‐associated increase in diatom motion at 0.25 mM Ca++, which was previously reported in the literature. Although the magnitude of the effect at 16 Hz was significant, the percentage of cells that moved was not sufficiently reproducible to allow examination for frequency dependence.
Extremely‐low‐frequency and very‐low‐frequency magnetic fields emitted by video display units
Authors: Tofani S. , D'Amore G. 
Published: February 2006

AbstractExtremely‐low‐frequency (ELF) and very‐low‐frequency (VLF) magnetic fields as emitted by monochrome and multichrome video display units (VDUs) were measured for their frequency domains. The rms magnetic‐flux densities (MFDs) were measured as a function of distance from all six sides of VDUs of four types. The MFDs at a distance of 30 cm from the screen (defined as the operator's position) were between 0.06 and 0.6 μT in the ELF range and between 0.02 and 0.06 μT in the VLF range. The contribution of harmonics to the total MFD was the same for both frequency ranges, less than 6%. For the first three harmonics, the MFD of each higher harmonic was one‐half that of the immediately lower harmonic.