bluuebunny/crossref_metadata_2025_split huggingface dataset:
Criticism of Lednev's mechanism for the influence of weak magnetic fields on biological systems
Authors: Adair Robert K. 
Published: February 2006

AbstractV. V. Lednev has proposed a mechanism that he suggests would allow very weak magnetic fields, at the cyclotron resonance frequency for Ca2+ ions in the earth's field, to induce biological effects. I show that for four independent reasons no such mechanism can operate. © 1992 Wiley‐Liss, Inc.
Effects of continuous and pulsed 2450‐MHz radiation on spontaneous lymphoblastoid transformation of human lymphocytes in vitro
Authors: Czerska Ewa M. , Elson Edward C. , Davis Christopher C. , Swicord Mays L. , Czerski Przemyslaw 
Published: February 2006

AbstractNormal human lymphocytes were isolated from the peripheral blood of healthy donors. One‐ml samples containing (106) cells in chromosome medium 1A were exposed for 5 days to conventional heating or to continuous wave (CW) or pulsed wave (PW) 2450‐MHz radiation at non‐heating (37°C) and various heating levels (temperature increases of 0.5, 1.0, 1.5, and 2 °C). The pulsed exposures involved 1‐μs pulses at pulse repetition frequencies from 100 to 1,000 pulses per second at the same average SAR levels as the CW exposures. Actual average SARs ranged to 12.3 W/kg. Following termination of the incubation period, spontaneous lymphoblastoid transformation was determined with an image analysis system. The results were compared among each of the experimental conditions and with sham‐exposed cultures. At non‐heating levels, CW exposure did not affect transformation. At heating levels both conventional and CW heating enhanced transformation to the same extent and correlate with the increases in incubation temperature. PW exposure enhanced transformation at non‐heating levels. This finding is significant (P < .002). At heating levels PW exposure enhanced transformation to a greater extent than did conventionalor CW heating. This finding is significant at the .02 level. We conclude that PW 2450‐MHz radiation acts differently on the process of lymphoblastoid transformation in vitro compared with CW 2450‐MHz radiation at the same average SARs. © 1992 Wiley‐Liss, Inc.
Residential exposure to 60‐Hz magnetic fields from appliances
Authors: Mader D. L. , Peralta S. B. 
Published: February 2006

AbstractA model has been developed that permits assessment of residential exposure to 60‐Hz magnetic fields emitted by appliances. It is based on volume‐ and time‐averaging of magnetic‐dipole fields. The model enables the contribution of appliances in the total residential exposure to be compared with that of other sources in any residence under study. Calculations based on measurements reported in the literature on 98 appliances revealed that appliances are not a significant source of whole‐body exposure, but that they may be the dominant source of exposure of the body's extremities. © 1992 Wiley‐Liss, Inc.
Preliminary report: Modification of cardiac contraction rate by pulsed magnetic fields
Authors: Ramon Ceon , Powell Michael R. 
Published: February 2006

AbstractIsolated rat hearts and excised canine cardiac tissues were subjected to pulsed magnetic fields. The fields excited in coils by tandem pairings of sinusoidal pulses were presented at various inter‐pair delays and repetition rates. The waveform of the magnetic field was a single or multiple sinusoid followed after a variable delay by another single or multiple sinusoid. Small but reliable increases in the beating rate of rat heart were observed. Similar increases occurred in contraction rates of canine tissues. Both preparations exhibited a contraction‐rate dependency on the repetition rate of the paired magnetic pulses: 4.5–6 rep/s for canine tissue, and 20–25 and 40–55 reps/s for rat heart. Flux‐density thresholds for both preparations approximated 10 mT (100 gauss) rms. © 1992 Wiley‐Liss, Inc.
Electric fields induced in rat and human models by 60‐Hz magnetic fields: Comparison of calculated and measured values
Authors: Hart Francis X. 
Published: February 2006

AbstractThe calculated distribution of electric fields induced in homogeneous human and rat models by a 60‐Hz magnetic field is compared with values measured in instrumented mannequins. The calculated values agree well with measured values. 1992 Wiley‐Liss, Inc.
Threshold for inhibition of Na, K‐ATPase by ELF alternating currents
Authors: Blank Martin , Soo Lily 
Published: February 2006

AbstractAlternating currents can increase or decrease the ATP‐splitting activity of the membrane enzyme Na,K‐ATPase. Either change depends on the AC frequency, and the greatest effect appears to be in the ELF range at about 100 Hz. The threshold for enzyme inhibition by AC was determined, and it is estimated to be an internal electric field circa 5 μV/cm. The corresponding current‐density threshold approximates 8 nA/cm2. 1992 Wiley‐Liss, Inc.
Relative‐risk‐estimate bias and loss of power in the mantel test for trend resulting from the use of magnetic‐field point‐in‐time (“spot”) measurements in epidemiological studies based on an ordinal exposure scale
Authors: Delpizzo Vincent , Salzberg Michael R. 
Published: February 2006

AbstractWe assessed the merits of various point‐in‐time (“spot”) measurement protocols in case‐control studies based on an ordinal exposure scale. After classifying a number of houses on the basis of prolonged monitoring of the ambient, extremely low frequency (ELF) magnetic field, we determined the probability of misclassification for each “spot” measurement protocol. We calculated the effect of this misclassification on the relative risk estimates and on the Mantel test for trend. We found that classification based on a small group of point‐in‐time measurements allows an adequate estimate of the relative risk, although the statistical significance of the dose‐response gradient may be seriously underestimated. However, the use of automated ambient‐field monitors, which results in loss of information on spatial variability, can lead to similar consequences. Therefore, manually collected point‐in‐time measurements remain a viable option for exposure assessment. 1992 Wiley‐Liss, Inc.
Increased sensitivity of the non‐human primate eye to microwave radiation following ophthalmic drug pretreatment
Authors: Kues Henry A. , Monahan John C. , D'Anna Salvatore A. , McLeod D. Scott , Lutty Gerard A. , Koslov Samuel 
Published: February 2006

AbstractPrevious studies in our laboratory have established that pulsed microwaves at 2.45 GHz and 10 mW/cm2 are associated with production of corneal endothelial lesions and with disruption of the blood‐aqueous barrier in the non‐human primate eye. In the study reported here we examined ocular damage in monkeys (M. mulatta and M. fascicularis) following topical treatment with one of two ophthalmic drugs (timolol maleate and pilocarpine) that preceded exposure to pulsed microwaves. Anesthetized monkeys were sham exposed or exposed to pulsed, 2.45 GHz microwaves (10 μs, 100 pps) at average power densities of 0.2, 1, 5, 10, or 15 mW/cm2 4 h a day for 3 consecutive days (respective SARs were 0.052, 0.26, 1.3, 2.6, and 3.9 W/kg). Immediately before microwave exposure, one or both eyes were treated topically with one drop of 0.5% timolol maleate or of 2% pilocarpine. Following administration of a drug, we observed a significant reduction in the power‐density threshold (from 10 to 1 mW/cm2) for induction of corneal endothelial lesions and for increased vascular permeability of the iris. Diagnostic procedures (in vivo specular microscopy and fluorescein iris angiography) were performed following each exposure protocol. In addition, increased vascular permeability was confirmed with horseradish peroxidase tracer techniques. Although we did not measure intraocular temperatures in experimental animals, the results suggest that a mechanism other than significant heating of the eye is involved. Our data indicate that pulsed microwaves at an average SAR of 0.26 W/kg, if administered after pretreatment with ophthalmic drugs, can produce significant ocular effects in the anesthetized primate. 1992 Wiley‐Liss, Inc.
Small integrating meter for assessing long‐term exposure to magnetic fields
Authors: Kaune W. T. , Niple J. C. , Liu M. J. , Silva J. M. , Ramirez J. 
Published: February 2006

AbstractA small, lightweight meter has been developed for magnetic‐field measurements, particularly those needed for exposure‐assessment purposes. This meter, known as the AMEX‐3D, continuously measures all three axes of magnetic‐flux density and electronically combines the data into a single estimate of cumulative exposure to the root‐mean‐square (rms) resultant flux density. The AMEX‐3D weighs about 120 g, measures 2.7 cm x 5.1 cm x 10.2 cm, and is battery powered. Two panel‐mounted jacks are provided for measuring battery voltage and for reading cumulative exposure data from the unit. The instrument has, within 3 dB, a flat response to magnetic flux densities at all frequencies in its 30–1,000 Hz bandwidth. A detailed analysis of error sources in the AMEX‐3D leads to an estimate of ±20% as the accuracy of the instrument over its dynamic range, which extends from 0.02 to 15 μT. The AMEX‐3D was tested in the field by asking electricutility distribution linemen to wear AMEX‐3D and EMDEX meters simultaneously while working. Agreement between the two measures of exposure was excellent. 1992 Wiley‐Liss, Inc.
Statistical review of the henhouse experiments: The effects of a pulsed magnetic field on chick embryos
Authors: Handcock Mark S. , Kolassa John E. 
Published: February 2006

AbstractThis paper analyzes data from a study conducted by the United States Office of Naval Research on the effects of pulsed magnetic fields on chick embryos. The experiment involved incubation of eggs under carefully controlled conditions in six different laboratories. The original analysis included inappropriate statistical methodology for analyzing the experimental results. Since the conclusions from this study rest so heavily on the results of statistical analyses, choosing the proper methodology is imperative. The major aim of this paper then is to introduce more appropriate analytic tools and illustrate their use in the present context. Qualitatively our results agree with those of the original analysis; our findings about interactions between effects, however, makes interpretation of these effects more subtle. We apply linear logistic modeling to counts of damaged embryos, using as covariates factors corresponding to exposure, laboratory, incubator, run, and measurements of background radiation. This facilitates estimation of the size of the effects. The effects of laboratory, incubator, and run are explored both as fixed and random effects. We find statistically significant exposure and laboratory effects, in accordance with the original study. However, we also find that the inter‐laboratory variation in exposure effect is at least as large as the exposure effect itself. The presence of such effects fundamentally alters the interpretation of the fitted model, as is graphically presented. 1992 Wiley‐Liss, Inc.
Early history of bioelectromagnetics
Authors: Schwan Herman P. 
Published: February 2006

AbstractThe early history of bioelectromagnetics is reviewed as I experienced it. The period of time chosen extends from my joining the Institute for Physical Foundations of Medicine in Frankfurt in 1937 to the early 1970s, when I retired from the chair of my department at the University of Pennsylvania. Several themes emerge from these recollections. First, clinical and biological work led almost immediately to a heated controversy about the role of athermal vs. thermal effects; this issue has never been settled to the satisfaction of most. Second, good quantitative work on electrical properties and dosimetry began early, well before World War II; its impact on future developments was significant. 1992 Wiley‐Liss, Inc.
Long‐term, low‐level microwave irradiation of rats
Authors: Chou C.‐K. , Guy A. W. , Kunz L. L. , Johnson R. B. , Crowley J. J. , Krupp J. H. 
Published: February 2006

AbstractOur goal was to investigate effects of long‐term exposure to pulsed microwave radiation. The major emphasis was to expose a large sample of experimental animals throughout their lifetimes and to monitor them for effects on general health and longevity.An exposure facility was developed that enabled 200 rats to be maintained under specific‐pathogen‐free (SPF) conditions while housed individually in circularly‐polarized waveguides. The exposure facility consisted of two rooms, each containing 50 active waveguides and 50 waveguides for sham (control) exposures. The experimental rats were exposed to 2,450‐MHz pulsed microwaves at 800 pps with a 10‐μs pulse width. The pulsed microwaves were square‐wave modulated at 8‐Hz. Whole body calorimetry, thermographic analysis, and power‐meter analysis indicated that microwaves delivered at 0.144 W to each exposure waveguide resulted in an average specific absorption rate (SAR) that ranged from 0.4 W/kg for a 200‐g rat to 0.15 W/kg for an 800‐g rat.Two hundred male, Sprague‐Dawley rats were assigned in equal numbers to radiation‐exposure and sham‐exposure conditions. Exposure began at 8 weeks of age and continued daily, 21.5 h/day, for 25 months. Animals were bled at regular intervals and blood samples were analyzed for serum chemistries, hematological values, protein electrophoretic patterns, thyroxine, and plasma corticosterone levels. In addition to daily measures of body mass, food and water consumption by all animals, O2 consumption and CO2 production were periodically measured in a sub‐sample (N=18) of each group. Activity was assessed in an open‐field apparatus at regular intervals throughout the study. After 13 months, 10 rats from each group were euthanatized to test for immunological competence and to permit whole‐body analysis, as well as gross and histopathological examinations. At the end of 25 months, the survivors (11 sham‐exposed and 12 radiation‐exposed rats) were euthanatized for similar analyses. The other 157 animals were examined histopathologically when they died spontaneously or were terminated in extremis.
Physiological interaction processes and radio‐frequency energy absorption
Authors: Adair Eleanor R. , Adams Barbara W. , Hartman Sharon K. 
Published: February 2006

AbstractBecause exposure to microwave fields at the resonant frequency may generate heat deep in the body, hyperthermia may result. This problem has been examined in an animal model to determine both the thresholds for response change and the steady‐state thermoregulatory compensation for body heating during exposure at resonant (450 MHz) and supraresonant (2,450 MHz) frequencies. Adult male squirrel monkeys, held in the far field of an antenna within an anechoic chamber, were exposed (10 min or 90 min) to either 450‐MHz or 2,450‐MHz CW fields (E polarization) in cool environments. Whole‐body SARs ranged from 0–6 W/kg (450 MHz) and 0–9 W/kg (2,450 MHz). Colonic and several skin temperatures, metabolic heat production, and evaporative heat loss were monitored continuously. During brief RF exposures in the cold, the reduction of metabolic heat production was directly proportional to the SAR, but 2,450‐MHz energy was a more efficient stimulus than was the resonant frequency. In the steady state, a regulated increase in deep body temperature accompanied exposure at resonance, not unlike that which occurs during exercise. Detailed analyses of the data indicate that temperature changes in the skin are the primary source of the neural signal for a change in physiological interaction processes during RF exposure in the cold. 1992 Wiley‐Liss, Inc.
Radio‐frequency electromagnetic fields associated with cellular‐radio cell‐site antennas
Authors: Petersen R. C. , Testagrossa P. A. 
Published: February 2006

AbstractBecause 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 cellsite 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 μW/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 roofmounted 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 (3μW/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. 1992 Wiley‐Liss, Inc.
A frequency‐dependent finite‐difference time‐domain formulation for induced current calculations in human beings
Authors: Gandhi Om P. , Gao Ben‐Qing , Chen Jin‐Yuan 
Published: February 2006

AbstractThe finite‐difference time‐domain (FDTD) method has been used to calculate SARs and induced currents involving whole‐body or partial‐body exposures of models to spatially uniform or nonuniform (far‐field or near‐field), to sinusoidally varying EM fields, or to transient fields such as those associated with electromagnetic pulses. However, a weakness of the FDTD algorithm is that the dispersion of the tissue's dielectric properties is ignored and frequency‐independent properties are assumed. Although this is permissible for continuous‐wave or narrow‐band irradiation, the results may be highly erroneous for short pulses, in which ultra‐wide bandwidths are involved. In some recent publications, procedures are described for one‐ and two‐dimensional problems for media in which the complex permittivity ϵ * (ω) may be described by a single‐order Debye relaxation equation or a modified version thereof. These procedures based on a convolution integral describing D(t) in terms of E(t) cannot be extended to human tissues for which multiterm Debye relaxation equations must generally be used.We describe here a new differential‐equation approach that can be used for general dispersive media. We illustrate the use of this approach by one‐ and three‐dimensional examples of media for which ϵ * (ω) is given by a multiterm Debye equation, and for an approximate two‐thirds muscle‐equivalent model of the human body. Based on a single run involving a Gaussian pulse, the frequency‐dependent FDTD [(FD)2TD] method allows calculations of SARs and induced currents at various frequencies by taking the Fourier components of the induced E fields. The (FD)2TD method can also be used to calculate coupling of the short (ultra‐wideband) pulses to the human body. 1992 Wiley‐Liss, Inc.
Microwave sensing of physiological movement and volume change: A review
Authors: Lin James C. 
Published: February 2006

AbstractThe ability non‐invasively to detect and monitor the movement of tissues and organs from outside the body provides many worthwhile areas of potential biomedical applications. Several non‐invasive microwave techniques for contact and remote sensing of circulatory and respiratory movements and volume changes have been developed. In general, these systems consist of a microwave generator, a sampling device, a transmitting‐receiving antenna, a set of signal‐conditioning and processing devices, and a display unit. They operate at continuous‐wave frequencies between 1 and 35 GHz and make use of amplitude and phase information derived from the received signal. The average power density of energy radiated by present systems ranges from approximately 0.001–1.0 mW/cm2. These systems are capable of registering instantaneous changes in fluid volume, pressure pulse, heart rate, and respiration rate in contact with body surface or at distances greater than 30 m, or behind thick layers of non‐conductive walls. 1992 Wiley‐Liss, Inc.
Microwave radiometry in biomedicine: A reappraisal
Authors: Foster Kenneth R. , Cheever Eric A. 
Published: February 2006

AbstractNearly 20 years ago the first papers appeared on biomedical applications of microwave radiometry, and many other papers have since appeared. Yet, despite its unique capabilities, microwave radiometry has so far received only limited acceptance by the medical community, and little commercial success. The chief reasons, we suggest, are the shallow depth of sensing and the difficulty of extracting imaging information from radiometry signals emitted by electrically heterogeneous media. A secondary factor has been the difficulty of validating many proposed clinical applications for the method—in particular, cancer detection. We suggest that microwave radiometry is a viable method of thermal sensing, but its successful applications are likely to be quite different than those that were originally conceived for the technique. 1992 Wiley‐Liss, Inc.
Evaluation of microwave hyperthermia applicators
Authors: Chou C.‐K. 
Published: February 2006

AbstractHyperthermia has been used in conjunction with radiation and chemotherapy for cancer treatment. When using electromagnetic heating, applicators are critical components in contact with or in proximity to patients and can be the determining factor for effective and safe treatment. Tissue absorption of electromagnetic energy is determined by many factors. Three cases are shown to illustrate the complexity of microwave heating: 1) The BSD MA‐151 applicator has good center heating on a muscle‐only phantom as shown in the operation manual. When fat slabs of 0.25, 0.5, 1, and 2 cm thick were added, two hot spots near the periphery of the applicator were evident on all fat surfaces, exposed at 631 MHz. At 915 MHz, the heating was elongated on the surface of the models with 0.25‐ and 2‐cm fat, and two hot spots were observed on the 0.5‐ and 1‐cm fat surfaces. 2) Heating patterns of the Clini‐Therm applicators on a muscle‐only phantom, as indicated in the operations guide, are elliptical with their major axes perpendicular to the electric field. However, when a bolus is used, the elliptical pattern is parallel to the E field. 3) Heating patterns in cylindrical structures were studied with inhomogeneous models of limbs. Arm and thigh models consisting of fat, bone, and muscle material were heated with Clini‐Therm L, M, and MS applicators at 915 MHz. In addition to the geometric effect, the results indicated that placing the applicators with E field parallel to the long axis of cylindrical structures can minimize required power, produce less heating of fats and reduce stray radiation. In conclusion, to apply penetrating microwave or other RF fields for tissue heating, one must simulate the clinical exposure conditions as closely as possible to obtain useful heating patterns. 1992 Wiley‐Liss, Inc.