bluuebunny/crossref_metadata_2025_split huggingface dataset:
An approach to inverse scattering problems
Authors: Saito Masao , Hayashi Takehisa 
Published: February 2006

AbstractThere 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.
Physiologic regulation in electromagnetic fields
Authors: Michaelson Sol M. 
Published: February 2006

AbstractElectromagnetic fields have been demonstrated to elicit thermoregulatory responses, neuroen‐docrine, neurochemical modulations, and behavioral reactions. These physiologic regulatory processes are exquisitely tuned, interrelated functions that constitute sensitive indicators of organismic responses to radiofrequency energy absorption (the radio frequency portion of the electromagnetic spectrum includes as one part microwaves). Assessment of the integration and correlation of these functions relative to the thermal inputs and homeokinetic reactions of the individual subjected to radiofrequency energy should permit differentiation between potential hazards that might compromise the individual's ability to maintain normal physiologic function and effects that are compensated by physiologic redundancy.
A comparative study of human sensory thresholds: 2450‐MHz Microwaves vs far‐infrared radiation
Authors: Justesen Don R. , Adair Eleanor R. , Stevens Joseph C. , Brucewolfe Virginia 
Published: February 2006

AbstractThree 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.
Accelerated development of spontaneous and benzopyrene‐induced skin cancer in mice exposed to 2450‐MHz microwave radiation
Authors: Szmigielski Stanislaw , Szudzinski Andrzej , Pietraszek Andrzej , Bielec Marian , Janiak Marek , Wrembel Jolanta K. 
Published: February 2006

AbstractC3H/HeA mice with high incidence of spontaneous breast cancer and Balb/c mice treated with 3,4‐benzopyrene (BP) (by painting of the skin resulting in the development of skin cancer) were irradiated with 2,450‐MHz microwaves (MW) in an anechoic chamber at 5 or 15 mW/cm2 (2 h daily, 6 sessions per week). C3H/HeA mice were irradiated from the 6th week of life, up to the 12th month of life. Balb/c mice treated with BP were irradiated either prior to (over 1 or 3 months) or simultaneously with BP treatment (over 5 months). The appearance of palpable tumors in C3H/HeA mice and of skin cancer in BP‐treated Balb/c mice was checked every 2 weeks for 12 months. Two additional groups of mice were exposed to chronic stress caused by confinement or to sham‐irradiation in an anechoic chamber; these served as controls. Irradiation with MWs at either 5 or 15 mW/cm2 for 3 months resulted in a significant lowering of natural antineoplastic resistance (mean number of lung neoplastic colonies was 2.8 ± 1.6 (SD) in controls, 6.1 ± 1.8 in mice exposed at 5 mW/cm2 and 10.8 ± 2.1 in those irradiated at 15 mW/cm2) and acceleration of development of BP‐induced skin cancer (285 days in controls, 230 days for 5 mW/cm2 and 160 days for 15 mW/cm2). Microwave‐exposed C3H/HeA mice developed breast tumors earlier than controls (322 days in controls, 261 days for 5 mW/cm2 and 219 days for 15 mW/cm2). A similar acceleration was observed in the development of BP‐induced skin cancer in mice exposed simultaneously to BP and MWs (285 days in controls, 220 day for 5 mW/cm2 and 121 days for 15 mW/cm2). The acceleration of cancer development in all tested systems and lowering of natural antineoplastic resistance was similar in mice exposed to MW at 5 mW/cm2 or to chronic stress caused by confinement but differed significantly from the data obtained on animals exposed at 15 mW/cm2, where local thermal effects (“hot” spots) were possible.
Electromagnetic dosimetry in a sitting rhesus model at 225 MHz
Authors: Olsen Richard G. , Griner Toby A. 
Published: February 2006

AbstractDosimetric measurements in a 9.5‐kg tissue‐equivalent rhesus model were conducted at 225 MHz using a nonperturbing temperature probe and a gradient‐layer calorimeter. Temperature probe measurements showed deep penetration of electromagnetic energy, and calorimeter experiments showed an average SAR (0.285 W/kg per mW/cm2) that was nearly three times greater than that observed for the same model at 1.29 GHz.
Assessment of the immune responsiveness of mice irradiated with continuous wave or pulse‐modulated 425‐MHz radio frequency radiation
Authors: Smialowicz R. J. , Riddle M. M. , Well C. M. , Brugnolotti P. L. , Kinn J. B. 
Published: February 2006

AbstractGroups of female BALB/C mice were irradiated with 425‐MHz radio frequency (RF) radiation either continuous wave (CW) or pulse modulated (PM, 1‐ms pulse width, 250 pulses/s). Mice were irradiated in a rectangular strip‐transmission line at average forward powers of 78, 17.7, or 5 W for CW and 17.7, 5, or 1.25 W for PM. The mean specific absorption rate, as measured using twin‐well calorimetry was 7.7 W/kg for a forward power of 70 W. No differences in the mitogen‐stimulated response of lymphocytes or in the primary antibody response to sheep erythrocytes or polyvinylpyrrolidone were observed between irradiated and sham‐irradiated mice, nor between mice exposed to either CW or PM 425‐MHz RF radiation.
Microwave radiation‐induced calcium ion efflux from human neuroblastoma cells in culture
Authors: Dutta S. K. , Subramoniam A. , Ghosh B. , Parshad R. 
Published: February 2006

AbstractMonolayer cultures of human neuroblastoma cells were exposed to 915‐MHz radiation, with or without sinusoidal amplitude modulation (80%) at 16 Hz, at specific absorption rates (SAR) for the culture medium and cells of 0.00, 0.01, 0.05, 0.075, 0.1, 0.5, 0.75, 1.0, 1.5, 2, or 5 mW/g. A significant increase in the efflux of calcium ions (45Ca2+) as compared to unexposed control cultures occurred at two SAR values: 0.05 and 1 mW/g. Increased efflux at 0.05 mW/g was dependent on the presence of amplitude modulation at 16 Hz but at the higher value it was not. These results indicate that human neuroblastoma cells are sensitive to extremely low levels of microwave radiation at certain narrow ranges of SAR.
System for the exposure of cell suspensions to power‐frequency electric fields
Authors: Kaune W. T. , Frazier M. E. , King A. J. , Samuel J. E. , Hungate F. P. , Causey S. C. 
Published: February 2006

AbstractA system is described that uses an oscillating magnetic field to produce power‐frequency electric fields with strengths in excess of those produced in an animal or human standing under a high‐voltage electric‐power transmission line. In contrast to other types of exposure systems capable of generating fields of this size, no electrodes are placed in the conducting growth media: the possibility of electrode contamination of the exposed suspension is thereby eliminated. Electric fields in the range 0.02–3.5 V/m can be produced in a cell culture with total harmonic distortions less than 1.5%. The magnetic field used to produce electric fields for exposure is largely confined within a closed ferromagnetic circuit, and experimental and control cells are exposed to leakage magnetic flux densities less than 5 μT. The temperatures of the experimental and control cell suspensions are held fixed within ±0.1°C by a water bath. Special chambers were developed to hold cell cultures during exposure and sham exposure. Chinese hamster ovary (CHO) cells incubated in these chambers grew for at least 48 h and had population doubling times of 16–17 h, approximately the same as for CHO cells grown under standard cell‐culture conditions.
Interaction between electromagnetic fields and cells: Microelectrophoretic effect on ligands and surface receptors
Authors: Chiabrera A. , Grattarola M. , Viviani R. 
Published: February 2006

AbstractThe aggregation between lectins and lymphocyte surface receptors can be affected strongly by a low‐level electric field induced in the cell suspension by a time‐varying magnetic field. One of the possible mechanisms is the microelectrophoretic effect due to the electric field, which influences the distance (in the mean square sense) between charged ligands and receptors when they are about to separate. On a purely theoretical basis, it is shown that, at low frequencies, an externally induced periodic electric field always decreases the mean lifetime of ligand‐receptor complexes. As a consequence, the mitogenic gain obtained by lectin addition to cell suspension is decreased. These results suggest that such a mechanism, if effective, reduces the lectin mitogenic capability and offers a way of handling similar phenomena which have been described for other biological systems.
Effects of acute low‐level microwaves on pentobarbital‐induced hypothermia depend on exposure orientation
Authors: Lai H. , Horita A. , Chou C. K. , Guy A. W. 
Published: February 2006

AbstractTwo series of experiments were performed to study the effects of acute exposure (45 min) to 2,450‐MHz circularly polarized, pulsed microwaves [1 mW/cm2, 2‐μs pulses, 500 pps, specific absorption rate (SAR) 0.6 W/kg] on the actions of pentobarbital in the rat. In the first experiment, rats were irradiated with microwaves and then immediately injected with pentobarbital. Microwave exposure did not significantly affect the extent of the pentobarbital‐induced fall in colonic temperature. However, the rate of recovery from the hypothermia was significantly slower in the microwave‐irradiated rats and they also took a significantly longer time to regain their righting reflex. In a second experiment, rats were first anesthetized with pentobarbital and then exposed to microwaves with their heads either pointing toward the source of microwaves (anterior exposure) or pointing away (posterior exposure). Microwave radiation significantly retarded the pentobarbital‐induced fall in colonic temperature regardless of the orientation of exposure. However, the recovery from hypothermia was significantly faster in posterior‐exposed animals compared to those of the anterior‐exposed and sham‐irradiated animals. Furthermore, the posterior‐exposed rats took a significantly shorter time to regain their righting reflex than both the anterior‐exposed and sham‐irradiated animals.
Operant behavior and colonic temperature of Macaca mulatta exposed to radio frequency fields at and above resonant frequencies
Authors: de Lorge John O. 
Published: February 2006

AbstractFive food‐deprived rhesus monkeys were exposed to 225‐MHz continuous‐wave, and 1.3‐GHz, and 5.8‐GHz pulsed radiation to determine the minimal power densities affecting performance. The monkeys were trained to press a lever (observing‐response) thereby producing signals that indicated availability of food. In the presence of the aperiodically appearing food signals, a detection response on a different lever was reinforced by a food pellet. Continuous, stable responding during 60‐min sessions developed and was followed by repeated exposures to radiofrequency radiation. The subjects, restrained in a Styrofoam chair, were exposed to free‐field radiation while performing the task. Colonic temperature was simultaneously obtained. Observing‐response performance was impaired at increasingly higher power densities as frequency increased from the near‐resonance 225 MHz to the above‐resonance 5.8 GHz. The threshold power density of disrupted response rate at 225 MHz was 8.1 mW/cm2; at 1.3 GHz it was 57 mW/cm2, and at 5.8 GHz it was 140 mW/cm2. These power densities were associated with reliable increases in colonic temperatures above sham‐exposure levels. The mean increase was typically in the range of 1°C, and response‐rate changes were not observed in the absence of concomitant temperature increases. In these experiments increase of colonic temperature was a much better predictor of behavioral disruption than was either the power density of the incident field or estimates of whole‐body‐averaged rates of energy absorption.
The effects of microwave radiation on avian dominance behavior
Authors: Wasserman F. E. , Dowd C. , Schlinger B. A. , Byman D. , Battista S. P. , Kunz T. H. 
Published: February 2006

AbstractSeventeen birds from 12 flocks were exposed to microwave radiation under various combinations of power density and duration; three birds from two additional flocks served as sham‐exposed controls. Experiments were conducted outdoors at Manomet, Massachusetts (41°56′N, 70°35′W) under normal winter ambient temperatures. Although irradiated birds maintained their positions within a flock hierarchy with one exception, some appeared to have a change in their level of aggression after exposure.
Formulas for preparing phantom muscle tissue at various radiofrequencies
Authors: Chou Chung‐Kwang , Chen Gang‐Wu , Guy Arthur W. , Luk Kenneth H. 
Published: February 2006

AbstractThe dielectric properties of various test samples of phantom tissue were measured using an automated and temperature‐controlled slotted line. The ingredients for phantom materials were determined for simulating high‐water content tissue at 13.56, 27.12, 40.68, 70, 100, 200, 300, 433, 750, 915, and 2,450 MHz. The ingredients consisted of water, TX‐150 (a gelling agent), sodium chloride, and polyethylene powder (200–2,450 MHz) or aluminum powder (13.56–100 MHz). The dielectric constant and conductivity of these materials at different temperatures (15, 22, 30°C) were characterized.
Energy deposition in a model of man in the near field
Authors: Stuchly Stanislaw S. , Kraszewski Andrzej , Stuchly Maria A. , Hartsgrove George , Adamski Daniel 
Published: February 2006

AbstractThe spatial distribution of the specific absorption rate (SAR) was measured in a full‐scale model of man using implantable electric field probes. The model was exposed in the near‐field of linear and aperture antennas at 350 MHz. Effects of the wave polarization, antenna position and antenna gain on the SAR distribution and the average SAR in the whole‐body and body parts are reported.
Active microwave tomographic imaging of isolated, perfused animal organs
Authors: Guerquin‐Kern J. L. , Gautherie M. , Peronnet G. , Jofre L. , Bolomey J. C. 
Published: February 2006

AbstractThe relative transparency of biological materials to high‐frequency electromagnetic waves has encouraged the development of new systems for imaging. This report describes experiments of microwave tomography conducted on a prototype. The object to be analyzed is submerged in water and is illuminated by a plane wave. The total electric field is analyzed by a microwave camera. The recorded data are then processed numerically in order to reconstruct the image that corresponds to the distribution of equivalent currents in a defined plane of a section. Experiments have been conducted on isolated kidneys with and without perfusion. The influence of the perfusing solution temperature has also been studied. These experiments show the potential of this system, especially through the correlation between microwave images and the biological structures. They also confirm previous results concerning spatial resolution and depth of exploration. Finally, the results demonstrate the influence of temperature and support the applicability of this imaging system in non‐invasive thermometry, especially for clinical hyperthermia.
Numerical calculation and measurement of 60‐Hz current densities induced in an upright grounded cylinder
Authors: Kaune W. T. , McCreary F. A. 
Published: February 2006

AbstractPower‐frequency electric fields are strongly perturbed in the vicinity of human beings and experimental animals. As a consequence, the extrapolation of biological data from laboratory animals to human‐exposure situations cannot use the unperturbed exposure field strength as a common exposure parameter. Rather, comparisons between species must be based on the actual electric fields at the outer surfaces of and inside the bodies of the subjects. Experimental data have been published on surface and internal fields for a few exposure situations, but it is not feasible to characterize experimentally more than a small fraction of the diverse types of exposures which occur in the laboratory and in the field. A predictive numerical model is needed, one whose predictions have been verified in situations where experimental data are available, and one whose results can be used with confidence in new exposure situations. This paper describes a numerical technique which can be used to develop such a model, and it carries out this development for a test case, that of a homogeneous right‐circular cylinder resting upright on‐end on a ground plane and exposed to a vertical, uniform, 60‐Hz electric field. The accuracy of the model is tested by comparing short‐circuit currents and induced current densities predicted by it to measured values: Agreement is good.
The extremely low frequency electrical properties of plant stems
Authors: Hart Francis X. 
Published: February 2006

AbstractThe electrical properties (variation of capacitance and conductance with frequency) of a plant stem can be conveniently measured in vivo by time domain dielectric spectroscopy. In this technique a voltage step is applied to a stem. The resulting polarization current is sampled by a microprocessor and Fourier‐transformed to yield these properties. Spectra were obtained for seven electrode separations along a Poinsettia stem. The inverse capacitance and conductance were plotted vs separation for 50 frequencies from .35 to 350 Hz. Least‐square fits yielded the effective dielectric constant and conductivity of the stem over this frequency range. In this way electrode effects were eliminated. A similar procedure was carried out for Coleus.A log‐log plot of dielectric constant vs frequency shows a two‐stage linear decrease for both plants. The conductivity is primarily DC. The dielectric loss decreases smoothly with frequency for Coleus. These results are compared to those for bone and the inorganic material hollandite. The dielectric properties seem best described by a cooperative, manybody approach.
Effects of microwave radiation (340 and 900 MHz) on different structural levels of erythrocyte membranes
Authors: Kim Y. A. , Fomenko B. S. , Agafonova T. A. , Akoev I. G. 
Published: February 2006

AbstractBy use of fluorescence probes 1‐anilinonaphthalene‐8‐sulfonic acid, 2‐toluidinylnaphthal‐ene‐6‐sulfonate, pyrene, perylene and chemical label phosphatidylethanolamine 2,4,6‐trinitrobenzele sulfonic acid, the effect of microwave radiation on the erythrocyte membrane was studied. The studies with the fluorescence probes were carried out on erythrocyte ghosts and with 2,4,6‐trinitrobenzene sulfonic acid on whole erythrocytes. The fluorescence was measured during irradiation of the membranes with 340‐MHz microwaves at an SAR of 100 W/kg. Trinitrophenylation of phosphatidylethanolamine from whole erythrocytes was performed simultaneously with microwave irradiation at 900 MHz (10 mW/cm2). It was shown that the microwave field decreased lipid viscosity, altered the structural state of lipid‐protein contact regions, and decreased the protein shielding of lipids. These changes corresponded to those produced by thermal action of microwaves.
A Role for the magnetic field in the radiation‐induced efflux of calcium ions from brain tissue in vitro
Authors: Blackman C. F. , Benane S. G. , Rabinowitz J. R. , House D. E. , Joines W. T. 
Published: February 2006

AbstractTwo independent laboratories have demonstrated that electromagnetic radiation at specific frequencies can cause a change in the efflux of calcium ions from brain tissue in vitro. In a local geomagnetic field (LGF) at a density of 38 microTesla (μT), 15‐ and 45‐Hz electromagnetic signals (40 Vp‐p/m in air) have been shown to induce a change in the efflux of calcium ions from the exposed tissues, whereas 1‐ and 30‐Hz signals do not. We now show that the effective 15‐Hz signal can be rendered ineffective when the LGF is reduced to 19 μT with Helmholtz coils. In addition, the ineffective 30‐Hz signal becomes effective when the LGF is changed to ±25.3 μT or to ± 76 μT. These results demonstrate that the net intensity of the LGF is an important variable. The results appear to describe a resonance‐like relationship in which the frequency of the electromagnetic field that can induce a change in efflux is proportional to a product of LGF density and an index, 2n + 1, where n = 0,1. These phenomenological findings may provide a basis for evaluating the apparent lack of reproducibility of biological effects caused by low‐intensity extremely‐low‐frequency (ELF) electromagnetic signals. In future investigations of this phenomenon, the LGF vector should be explicitly described. If the underlying mechanism involves a general property of tissue, then research conducted in the ambient electromagnetic environment (50/60 Hz) may be subjected to unnoticed and uncontrolled influences, depending on the density of the LGF.
Neuroendocrine parameters in the rat exposed to 60‐Hz electric fields
Authors: Quinlan William J. , Petrondas Demetrios , Lebda Nancy , Pettit Sue , Michaelson Sol M. 
Published: February 2006

AbstractThis study was designed to assess the neuroendocrine response of male Long‐Evans rats to sustained or intermittent 60‐Hz electric fields when exposed for 1 or 3 h at 100 kV/m. No significant differences were noted in corticosterone, prolactin, or thyrotropin levels between exposed and sham‐exposed rats. A statistically significant increase (P < .01) in growth hormone was noted in rats exposed to intermittent electric fields for 3 h. Emphasis was placed on good experimental design and the need to avoid standard laboratory stressors (excessive handling, temperature extremes, transportation, noise, etc.) known to be present in many biomedical studies. The importance of avoiding reactions due to extraneous factors in experiments predicated on investigating physiological function in relation to electric field exposure is discussed.