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This study investigates the role of age and sex on the cardiovascular effects of 3.5-MHz pulsed ultrasound (US) in a rat model. Ultrasonic bursts of 2.0-MPa peak rarefactional pressure amplitude (equivalent to an in vitro spatial-peak temporal-peak intensity of ~270 W/cm2 and a mechanical index of 1.1) were delivered in five consecutive 10-s intervals, one interval for each pulse repetition frequency (PRF) (6, 5, 4, 5, and 6 Hz; always the same order) for a total exposure duration of 50 consecutive seconds. Sixty F344 rats were split into 12 groups in a $3\times 2\times2$ factorial design (three ages, male versus female, and US application versus control). This study is the first study on US-induced cardiac effects that contains data across three age groups of rats (premenopause, fertile, and postmenopause) to mimic the fertile and nonfertile human window. US was applied transthoracically, while heart rate, stroke volume, ejection fraction, temperature, and other physiologic parameters were recorded at baseline and after exposure. Significant decreases in cardiac output compared to respective control groups were observed in multiple experimental groups, spanning both females and males. A negative chronotropic effect was observed in young male (~7%) and female (~16%) rats, in five-month-old male (~9%) and female (~15%) rats, and in old rats where the effect was not statistically significant. Younger groups and, to a lesser extent, lower weight groups generally had more significant effects. The pathophysiology of US-induced cardiovascular effects appears to be multifactorial and not strictly related to hormones, menopause, weight, sex, or age, individually. [ABSTRACT FROM AUTHOR]

The impact of pulse repetition rate (PRR) in modulating electroporation (EP) induced by nanosecond pulsed electric fields (nsPEFs) in mammalian cells was approached here by performing both biological and numerical analysis. Plasma membrane permeabilization and viability of Jurkat cells were analyzed after exposure to 500, 1.3 MV/m, 40 ns PEFs with variable PRR (2–30 Hz). A finite-element model was used to investigate EP dynamics in a single cell under the same pulsing conditions, by looking at the time course of transmembrane voltage and pore density on the ns time scale. The biological observations showed an increased EP and reduced viability of the exposed cells at lower PRR in the considered range. The numerical analysis resulted in different dynamics of plasma membrane response when ns pulses were delivered with different PRR, consistently with a phenomenon of electrodesensitization recently hypothesized by another research group. [ABSTRACT FROM AUTHOR]

We developed a millimeter-wave (MMW) exposure system for in vivo experiments for operating frequencies ranging from 24.5 to 95 GHz. The MMWs are localized to the rabbit ocular tissue with a spot-focus lens antenna. The MMW energy absorption and consequent temperature elevation are evaluated by numerical simulation using measured antenna distribution and precisely modeled rabbit ocular data. Results suggest that corneal damage occurs at an incident power density of 300 \mW/cm^2 with our exposure system at frequencies from 26.5 to 95 GHz. [ABSTRACT FROM PUBLISHER]

A new setup for exposure of human cells in vitro at 37 °C to pulse-modulated 300 and 500 MHz signals of future magnetic resonance imaging (MRI) systems is designed, built up, and characterized. Two dipole antennas, specifically designed for ultrahigh field MRI, are used as radiating structures. The electromagnetic (EM) field distribution inside the incubator containing the cells is computed, and it is shown to be in a good agreement with measurements. The electric field at the cell level is quantified numerically. Local, 1-g average, and averaged over the culture medium volume SAR are provided along with the standard deviation values for each well. Temperature increments are measured inside the culture medium during the exposure using an optical fiber thermometer. Then, we identify the pulse parameters corresponding to the thermal threshold of 1 °C, usually considered as a threshold for thermally induced biological effects. For these parameters, the induction of heat shock proteins is assessed to biologically verify a potential thermal response of cells. The data demonstrate that, under the considered experimental conditions, exposure to pulse-modulated radiations emulating typical ultrahigh field MRI signals, corresponding to temperature increments below 1 °C, does not trigger any heat shock response in human brain cells. [ABSTRACT FROM PUBLISHER]

The understanding of possible nonthermal bio-effects has been an open question during the last five decades. In this paper, the authors present a critical literature review of the models of the interaction mechanisms, together with an overview of all the publications finding positive results for in vitro and in vivo studies. The systematic approach consisted of pooling together the positive studies on the basis of the endpoints and the biological systems, to identify specific plausible targets of the action of the electromagnetic fields and the related pathways. Such a classification opens the way to the discussion of some hypotheses of interaction mechanisms considered as first transduction step. The authors conclude that only through a multiscale methodology it is possible to perform a comprehensive study of the nonthermal effects, based on affordable and realistic in silico models. [ABSTRACT FROM PUBLISHER]

In this paper, a numerical dosimetry scheme is proposed for pulsed high-power electromagnetic (HPEM) sources, which may induce biological effects such as “microwave hearing.” This auditory effect is linked to the specific absorption (SA) of biological tissue which is subject to regulatory limits. The presented simulation scheme using high-resolution human body phantoms takes into account the widespread spectral excitation range of pulse sources with the frequency dependency of dispersive biological tissue properties and of corresponding regulatory restrictions. Different examples of numerically computed and evaluated HPEM exposure scenarios are presented. [ABSTRACT FROM PUBLISHER]

We investigate potential biological effects of low-power millimeter-wave radiation on human cell viability and intracellular protein homeostasis. A specific exposure system allowing to perform far-field exposures with power densities close to those expected from the future wireless communications in the 60-GHz band has been developed and characterized. Specific absorption rate (SAR) values were determined for the biosamples under test using the FDTD method. It was shown that millimeter-wave radiation at 60.42 GHz and with a maximum incident power density of 1 mW/cm² does not alter cell viability, gene expression, and protein conformation. [ABSTRACT FROM AUTHOR]

In order to assess the compliance of ingested wireless device (IWD) with related international safety guidelines, the studies on the biological effects and the signal intensity of an IWD in two realistic human body models using the finite-difference time-domain (FDTD) method are reported in this paper. Simulation studies are carried out in 21 scenarios where the IWD is placed at seven positions with three orientations, for each of the two human models. Specific absorption rate (SAR), temperature rise, near fields and far fields are analyzed in the 21 scenarios at four selected operation frequencies of 430 and 800 MHz, and 1.2 and 2.4 GHz, respectively. Our study indicates that the radiation intensity outside of the human body decreases with the increase of operation frequency. Furthermore, the radiation characteristics of the IWD are orientation and position dependent. The polarization of electric field outside of the human body is similar to that of the Radio Frequency (RF) source. As far as the compliance of safety is concerned, among all the simulated scenarios the maxima of the averaged-1g and averaged-10g SARs can reach 3.71 W/kg and 1.37 W/kg at the input power of 25 mW, respectively. [ABSTRACT FROM AUTHOR]

Naturally occurring electromagnetic oscillating fields in the very-low-frequency (VLF) range of the spectrum, i.e., from 1 to 200 kHz, are weak and difficult to detect tinder normal conditions. These naturally occurring VLF electromagnetic events are observed during thunderstorms, in certain mountain winds, and during earthquakes. On the other hand, man-made VLF electromagnetic fields are stronger and have been suspected of causing negative health effects. Typical sources of these VLF emissions include television sets, video display terminals (VDTs), certain medical devices, some radio stations, and the ground-wave emergency network (GWEN) used for military communications. This paper describes the development of a triaxial "VLF gauss- meter," which can be made portable. This electronic system can be used to monitor VLF electromagnetic radiation in residential and occupational environments. The "VLF gaussmeter" is based on a microcontroller with a built-in 10-bit A/D converter and has been designed to measure the magnetic flux density and frequency across the wide VLF bandwidth (BW). A digitized resolution of 0.2 mG is used for the 0-200-mG range, and 2-mG resolution is used for the range of 2-2000 mG. The meter has been designed to include the following features: 1) automatic or manual range selections 2) data logging; 3) single-axis mode; 4) peak hold; 5) RS-232 communication port; and 6) analog recorder output. [ABSTRACT FROM AUTHOR]

In some cases, a publication - and more often, a conference presentation - reports preliminary results or work in progress. Results from these experiments, by nature, consist of a small number of cases and are first tests, to be repeated in further studies. It should be noted that presentation or publication of incomplete studies or preliminary results primarily serves as a means of communication among scientists to apprize each other of ongoing research activity. There are a number of general principles that should be applied in the evaluation of the scientific literature. For studies of biological effects of microwave radiation, it is important that the published description of methods should be given in sufficient detail that a critical reviewer would be convinced that all reasonable precautions were taken to meet requirements 1, 2, and 3. In analyzing the scientific literature to determine the probability of a biological response from exposure to microwave energy, one must consider: 1) the consistency of experimental results claimed; 2) the nature of the response and the biological system involved; 3) the ability to consistently replicate the results; and 4) whether results claimed and observations reported can be explained by previously accepted biological principles or must be explained only on the basis of new, untested hypotheses. Once an individual report has been reviewed to assure its reliability, results of that report must be considered in light of existing scientific principles and results of other studies of the same parameter under investigation. The results of an individual report should be compared to the rest of the literature being reviewed. Experiments with small animals, such as mice and rats that are undertaken to evaluate the potential effects of microwave exposure, must be carefully evaluated for their potential effects in humans. Differences in species, SAR, and specific absorption (SA) necessitate judicial extrapolations from experimental animals to humans based on J.C. Lin and O.P. Gandhi (1996). Moreover, any unrelated stressor - i.e., anesthetic, drugs, animal care, restrainers, ambient temperature, noise, etc. - could become a compounding factor. A reported observation may be the result of an unrelated st- ressor not intended to be studied. [ABSTRACT FROM PUBLISHER]

A decade ago, a major research initiative, with orchestrated monetary and programmatic support from both industry and the government, was launched to investigate the biological effects and health implications of radio frequency (RF) radiation emitted from cellular mobile telephones. The subject remains a focus of public concern and shows no sign of relenting. There is a lack of scientific consensus on experimental studies that provide clear evidence either refuting or supporting the cancer induction or promotion potential of RF and microwave radiation from cell phones. The uncertainties persist, in part, because of the limited number and scope of studies that have been undertaken. [ABSTRACT FROM PUBLISHER]

There are considerable public concerns regarding the biological effects and safety of microwave exposure from wireless base stations. There have been repeated calls for measures and tools that would reduce the exposure to microwave radiation from cellular mobile telephone operations. The radiated power from a base station antenna can vary from less than 1 to as high as 500 W per channel (or transmitter), depending on the location and type of the antenna used for a cellular communication system. The level of public exposure to microwave energy from any base station varies depending on antenna type, location, and distance from the base station. The microwave exposure a person receives from a base station thus depends on both the distances from the antenna, and the angle below the direction of the main beam. [ABSTRACT FROM PUBLISHER]

The assets and working philosophy of individual electric utilities will, in large measure, be reflected by the modernization of their power systems during the next 20 years. This part, which concludes the article, addresses DC transmission, dispersed generation, distributed automation, use of computer information technology, and other factors worthy of continued consideration in the twenty-first century (grid stability, superconducting generators, energy storage, voltage sags, power system planning and operations, biological effects of EM fields) [ABSTRACT FROM PUBLISHER]

In this letter, the dosimetry for pregnant rats and their fetuses in an in vivo exposure setup is conducted by using the finite-difference time-domain method in conjunction with anatomically based pregnant rat models. The exposure setup has been developed for testing possible indirect biological effects on fetuses when the pregnant rats are exposed to 1.95-GHz digital cellular phones. As a result, it is found that the whole-body average specific absorption rate (SAR) for the fetuses varies between 0.02-0.40 W/kg when the brain-average SAR for the mother rats varies between 1.4-2.6 W/kg. [ABSTRACT FROM PUBLISHER]

A recent article offering a systematic review of the outcome of experimental studies reported in scientific journals and sources of funding for the reported research suggested that the evaluation of results from existing and future studies of health effects of microwave radiation from wireless communication should take sponsorship into account. This finding was not altered after adjusting for the number of outcomes reported, study design and quality, exposure characteristics, or outcomes. Note that a majority (68%) of the studies evaluated showed biological effects, although at present it is unclear whether the biological effects translate into relevant health hazards. [ABSTRACT FROM PUBLISHER]

A recent report issued by EMF-NET offers a lengthy list of European projects on the biological effects of power line and wireless communication electromagnetic fields. The list also includes projects on potential risks related to exposure in the working environment. The EMF-NET project is an initiative of the EC and is titled "Effects of the exposure to electromagnetic fields: from science to public health and safer workplace." This four-year project, which is to conclude in 2008, is one of the most ambitious and all-encompassing programs funded by the EC to date. It targets exposures from a wide range of nonionizing electromagnetic-energy-emitting devices, sources, and systems - including power lines, cellular mobile phones, base stations, broadcasting antennas, and household electrical appliances such as mixers and induction ovens (IH hobs) - as well as various electromagnetic equipment found in industry environments and health care facilities [ABSTRACT FROM PUBLISHER]