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Calculation of electromagnetic field components for a fundamental Gaussian beam.

Using a perturbative method, we carefully calculate seventh- and ninth-order expressions for electromagnetic field components for a fundamental Gaussian beam (i.e., a focused TEM00 mode laser beam) propagating in the medium analogous to vacuum. The interaction of a single electron and a focused laser pulse in vacuum has a promising application in the design of a powerful electron accelerator which could compete with the traditional ones. For this, ninth-order accuracy in the expansion describing the focused laser beam is required. When the vector potential corresponds to polarization along the direction of propagation, the number of electromagnetic field components can be reduced from 5 or 6 to 3. Furthermore, we find two rules obeyed by all orders of the vector potential, which greatly simplify the calculation procedure of the vector potential order by order, and make it possible to investigate the behavior of high orders.

Journal Article↗

Low-level exposure to radiofrequency electromagnetic fields: health effects and research needs.

The World Health Organization (WHO), the International Commission on Non-Ionizing Radiation Protection (ICNIRP), and the German and Austrian Governments jointly sponsored an international seminar in November of 1996 on the biological effects of low-level radiofrequency (RF) electromagnetic fields. For purposes of this seminar, RF fields having frequencies only in the range of about 10 MHz to 300 GHz were considered. This is one of a series of scientific review seminars held under the International Electromagnetic Field (EMF) Project to identify any health hazards from EMF exposure. The scientific literature was reviewed during the seminar and expert working groups formed to provide a status report on possible health effects from exposure to low-level RF fields and identify gaps in knowledge requiring more research to improve health risk assessments. It was concluded that, although hazards from exposure to high-level (thermal) RF fields were established, no known health hazards were associated with exposure to RF sources emitting fields too low to cause a significant temperature rise in tissue. Biological effects from low-level RF exposure were identified needing replication and further study. These included in vitro studies of cell kinetics and proliferation effects, effects on genes, signal transduction effects and alterations in membrane structure and function, and biophysical and biochemical mechanisms for RF field effects. In vivo studies should focus on the potential for cancer promotion, co-promotion and progression, as well as possible synergistic, genotoxic, immunological, and carcinogenic effects associated with chronic low-level RF exposure. Research is needed to determine whether low-level RF exposure causes DNA damage or influences central nervous system function, melatonin synthesis, permeability of the blood brain barrier (BBB), or reaction to neurotropic drugs. Reported RF-induced changes to eye structure and function should also be investigated. Epidemiological studies should investigate: the use of mobile telephones with hand-held antennae and incidence of various cancers; reports of headache, sleep disturbance, and other subjective effects that may arise from proximity to RF emitters, and laboratory studies should be conducted on people reporting these effects; cohorts with high occupational RF exposure for changes in cancer incidence; adverse pregnancy outcomes in various highly RF exposed occupational groups; and ocular pathologies in mobile telephone users and in highly RF exposed occupational groups. Studies of populations with residential exposure from point sources, such as broadcasting transmitters or mobile telephone base stations have caused widespread health concerns among the public, even though RF exposures are very low. Recent studies that may indicate an increased incidence of cancer in exposed populations should be investigated further.

Animals↗

[Levels of the electromagnetic field in the vicinity of therapeutic devices using radiofrequency and microwaves].

The paper presents the results of an analysis made on the electromagnetic field levels around RF and MW equipment used for medical purposes to achieve induced thermogenesis in body areas affected by disease. An irradiation diagram was constructed for some of the most widely used devices in clinical practice and measurements were made on RF devices to identify the influence of obstacles in determining electric field levels, such as accessories or persons present in the working environment. Electric field and power density levels were checked, as can be measured at a distance of 100 cm at identical selected power during a typical "lumbar-dorsal spine" treatment using different types of RF and MW devices, to identify the different degree of electromagnetic pollution that each of the devices causes.

Diathermy↗

Effects of extremely low frequency electromagnetic fields on membrane-associated enzymes.

The effects of extremely low frequency electromagnetic fields of 75 Hz were studied on different membrane-associated enzymes. Only the activities of three enzymes out of seven exposed to the field decreased approximately of about 54-61% with field amplitudes above a threshold of 73-151 microT depending on the enzyme. The same field had no effect on the activities of either integral membrane enzymes such as Ca,ATPase, Na/K,ATPase, and succinic dehydrogenase or peripheral membrane enzymes such as photoreceptor PDE. The decrease in enzymatic activity of the field-sensitive enzymes was independent of the time of permanence in the field and was completely reversible. When these enzymes were solubilized with Triton, no effect of the field was obtained on the enzymatic activity, suggesting the crucial role of the membrane in determining the conditions for enzyme inactivation. The role of the particular linkage of the field-sensitive enzymes to the membranes is also discussed.

Cell Membrane↗

The electric field induced in the human body when exposed to electromagnetic fields at 1-30 MHz on shipboard.

The electric field induced in the body of a man standing on the metal deck of a ship near a vertical antenna is determined analytically. Typical antennas for radio communication in the 1-30 MHz band are described and their near fields are calculated. The current induced in the man is determined by solving the relevant integral equation. Explicit formulas are obtained for the total axial current and the associated current densities and electric fields.

Electric Conductivity↗

Space environment, electromagnetic fields, and circadian rhythm.

Human space activity began in 1961. About 400 persons have gone to space since then, and about 70 of them have stayed more than 1 month. Circadian rhythm and sleep in space have been investigated several times, though the effect of longer stays in space has not been adequately clarified. Electromagnetic fields are different in the space environment, especially in deeper space missions, such as the Moon or Mars, but their effects on human health have rarely been studied. In this article, we summarize the current status of the International Space Station project, study circadian rhythm and sleep in space, investigate electromagnetic fields, and state the necessity for investigating this research field.

Circadian Rhythm↗

Vibration as a possible explanation for putative electromagnetic field effects: a case study on marine diatoms.

PURPOSE: We examined the conjecture that mechanical vibration, being an uncontrolled and variable factor from one trial to another, might explain the inconsistency of results from investigations of the influence of extremely low frequency electromagnetic fields on the Ca-dependent motility of marine diatoms (Amphora coffeaeformis, strain #2038). MATERIALS AND METHODS: Owing to slight differences in culture of diatoms in previous studies, culture techniques are described in detail here. Diatoms showed maximal motility in logarithmic growth and motility was dependent on external [Ca], reducing at <.25 mM added Ca. Ninety-six different vertical vibration treatments were applied to the petri dishes containing the agar on which the diatoms were placed. The envelope of amplitudes varied from 50-500 pmicro at 10Hz to 100 nm-l1mmicro at 500 Hz. RESULTS: No significant effect of the mechanical vibrations on the motility response of diatoms was observed. We were unable to impose deliberate vibrations in a horizontal direction though some component of horizontal movement was probably present in our tests. CONCLUSIONS: The results imply that the variability of earlier experiments with extremely low frequency electromagnetic fields is unlikely to be ascribable to mechanical vibration.

Animals↗

Effects of a pulsed electromagnetic field on a mixed chondroblastic tissue culture.

A mixed tissue culture predominantly composed of chondroblastic tissue was perturbed by a pulsed electromagnetic field (PEMF). Some cultures were nonconfluent, and purposely retarded in growth to resemble an atrophic nonunion, while others were grown to confluence in about one-half the time as a model for a hypertrophic nonunion. These two groups tested the effect of growth rate upon the products of cell proliferation and differentiation. The slowly growing cultures were stimulated to synthesize hydroxyproline. The rapidly growing cultures showed a large increase in lysozyme activity, and increase in hyaluronate and DNA, and a decrease in glycosaminoglycan. Exogenous lysozyme further decreased the glycosaminoglycan synthesis in the presence of PEMF. Chitotriose, a specific lysozyme inhibitor abolished this effect. Cycloheximide, a protein synthesis inhibitor, did not abolish the activation of lysozyme found in the matrix. Thus lysozyme appears to be activated by PEMF. These observations of the rapidly growing confluent cultures are consistent with events described in the normal healing of a bone fracture or endochrondral growth. Thus, PEMF appears to promote normal healing, probably by altering cartilaginous lysozyme activity in the matrix, and possibly the sequence of events leading to calcification.

Animals↗

A preliminary study of oscillating electromagnetic field effects on human spermatozoon motility.

Some effects of extremely low frequency electromagnetic fields (ELF-EMFs) on human spermatozoa are reported. Significant increases in the values of the motility and of the other kinematic parameters have been observed when spermatozoa were exposed to an ELF-EMF with a square waveform of 5 mT amplitude and frequency of 50 Hz. By contrast, a 5 mT sine wave (50 Hz) and a 2.5 mT square wave (50 Hz) exposure did not produce any significant effect on sperm motility. The effects induced by ELF-EMF (50 Hz; 5 mT) during the first 3 h of exposure persisted for 21 h after the end of the treatment. These results indicate that ELF-EMF exposure can improve spermatozoa motility and that this effect depends on the field characteristics.

Cells, Cultured↗

Occupations with exposure to electromagnetic fields: a possible risk factor for Alzheimer's disease.

The authors present analyses of data from three independent clinical series and controls indicating an association between working in occupations with probable medium to high exposure to extremely low frequency (< 300 Hz) electromagnetic fields and sporadic Alzheimer's disease. Case-control analyses were carried out using data from patients examined at the following locations: the Department of Neurology, University of Helsinki, Helsinki, Finland, 1982-1985; the Koskela Hospital in Helsinki, 1977-1978; and the University of Southern California site of the Alzheimer's Disease Research Center of Los Angeles and Orange Counties, 1984-1993. The predominant occupations among medium (2-10 mG or > 10 mG intermittently) to high (> 10 mG or > 100 mG intermittently) exposed cases were seamstress, dressmaker, and tailor. The results appear to be independent of education, and the sex-combined odds ratios for the three series are quite homogeneous: 2.9, 3.1, and 3.0. The odds ratio for the three series analyzed together is 3.0 (p < 0.001), with a 95% confidence interval of 1.6-5.4. The odds ratio for women is 3.8 (p < 0.001), with a 95% confidence interval of 1.7-8.6. The most obvious, possibly etiologically relevant exposure is that of electromagnetic fields, which may have biologic plausibility because they may adversely influence calcium homeostasis and/or inappropriately activate immune system cells such as microglial cells, initiating events that result in neuronal degeneration.

Aged↗

A non-operative salvage of surgically-resistant pseudarthroses and non-unions by pulsing electromagnetic fields. A preliminary report.

This report documents, for the first time, to the authors' knowledge, the therapeutic use in humans of low energy, electromagnetic fields pulsing in the extremely low frequency (E.L.F.) range. These fields, established outside the body, were used to treat congenital and acquired pseudarthroses and non-unions. Energy of this type appears to affect biological processes, not through heat production, but through electrically-induced changes in the environment of cells within the organism. Of the 29 patients included in the study, 17 had experienced at least one failure of surgical repair and, in each of these, amputation had been recommended. The overall success rate, including those patients treated with inadequate pulse characteristics and those who failed to follow the protocol, was in excess of 70 per cent. Improvements in the specificity of pulse characteristics hold promise for increasing the rate of success. The simple, clinical methodology, which is conducted on an out-patient basis, appears to be both safe and effective. It can be applied with or without surgery. This approach requires additional controlled investigations before it is ready for general use in the orthopaedic community. The indications for amputation of surgically-resistant pseudarthroses, however, should be reassessed. The principles and technology, which have been established during this endeavor, may have physiologic and practical significance for processes other than pseudarthrosis and non-union.

Adolescent↗

The epidemiology of exposure to electromagnetic fields: an overview of the recent literature.

Epidemiologic studies of exposure to electromagnetic fields (EMF) have been reviewed. Possible links to incidences of cancer and abnormal fetal development have been suggested by some investigators. In general, the results have been inconsistent. There are many deficiencies in the studies, and many questions have been raised about the validity of some of the conclusions proposed. There is currently no definitive evidence of an association between exposure to EMF and the alleged risks. Due to problems and limitations inherent in future studies (misconceptions about exposure levels, uncertainty about field variability, criticisms of surrogate measures), this question is unlikely to ever be answered with certainty. Unfortunately, many highly-publicized accounts of speculative and unsubstantiated claims have caused undue concern among the general public.

Electromagnetic Fields↗

Electro-optic fiber sensor for amplitude and phase detection of radio frequency electromagnetic fields.

We present a miniature fiber-optic electromagnetic field (EMF) sensor that is capable of simultaneously detecting the amplitude and phase of an EMF in the range of 0.1-6 GHz. We focus on magnetic field measurements, since the H-field is more significant in our target applications due its direct relation to the current. The sensor is based on an open optical platform to which various antennas can be attached and contains a radio-frequency amplifier for signal conditioning and a vertical-cavity surface-emitting laser as an electro-optic converter. The millimeter size and the full electrical isolation of the sensor allow EMF detection with minimal disturbance. We have characterized the sensor in the near field of a lambda/2 dipole, a rectangular waveguide, and a microstrip line, and we explain the experimental results with a simple theoretical model confirming the mapped near-field distribution of the investigated field source.

Journal Article↗

Effects of pulsed low-frequency electromagnetic fields on water characterized by light scattering techniques: role of bubbles.

Well-characterized purified water was exposed for 6 h to pulsed low-frequency weak electromagnetic fields. After various time periods, nondegassed and degassed water samples were analyzed by static light scattering. Just after electromagnetic exposure (day 0), a reduction of over 20% in the maximum light scattering intensity at 488 nm wavelength in both nondegassed and degassed samples was observed. By contrast, on day 12 the difference was observed only in nondegassed water samples. The latter effect was attributed to the different geometries of the containers combined with the basic origin of the whole phenomenon due to gas bubbles present in water. By the use of dynamic light scattering, the bubble mean diameter was estimated to be around 300 nm. Our results suggest that the electromagnetic exposure acts on gas nanobubbles present in water and emphasizes the role of the gas/liquid interface. The possibility that exposure to electromagnetic fields disturbs the ionic double layer that contributes to bubble stabilization in water is discussed.

Journal Article↗

Health hazards and electromagnetic fields.

Biological rhythms, physical wellbeing and mental states are dependent on our electrical brainwave system interacting with the extremely weak electromagnetic fields generated by the Earth's telluric and Cosmic radiations. In a single generation, since the evolution of humankind over millions of years, we are exposed to a wide range of powerful, artificially generated electromagnetic radiation which adversely affects the subtle balance in nature's energy fields and has become the source of so-called 'diseases of civilization'. This also includes electromagnetic sensitivity. Generally, there is a lack of awareness and understanding of the impact electromagnetic fields can have upon health and wellbeing.Our ancestors were acutely aware that certain locations, were perceived to have a positive energy field which was beneficial to health and vitality. Over time, these areas are now referred to as sacred sites for spiritual ceremony and as healing centres. In contrast, there are other geographical locations that can have a negative effect upon health and these are known as geopathic stress zones. It is believed that such zones can interfere with the brain's normal function that inhibits the release of melatonin and other endocrine secretions needed to replenish the immune system. Geopathic stress can affect animals and plant life as well as human beings and significantly contributes to sick building syndrome (SBS). Whilst there is an increasing body of opinion amongst eminent researchers and scientists who are addressing these issues, the establishment professions are slow to change. However, very gradually, modern allopathic medicine and attitudes are beginning to recognise the extraordinary wisdom and efficacy of ancient traditions such as acupuncture, light, colour and other therapies based on the understanding and treatment of the interaction of a person's electromagnetic subtle body and the immediate environment. These and many other 'complementary' therapies may soon become mainstream medical practice. In the meantime, we can help ourselves by learning how to detect the hazards and daily practise prudent avoidance.

Abnormalities, Radiation-Induced↗

Growth stage dependent effects of electromagnetic fields on DNA synthesis of Jurkat cells.

A 1.8 mT, bone healing, electromagnetic field (EMF) and power frequency EMFs of 0.1 and 0.4 mT significantly inhibit DNA synthesis in otherwise unstimulated Jurkat (E 6.1) cells. Inhibition is generally most prominent in cells from mid log phase growth. In complete medium the bone healing EMF inhibits [3H] thymidine uptake of the latter cells by almost 50% vs. 20-25% inhibition by 60 Hz fields. Cells in conditioned medium are even more sensitive to EMFs with inhibition up to ca. 60%. The effects of the 0.1 and 0.4 mT power frequency EMFs were very similar suggesting saturation at 0.1 mT or lower.

Cell Division↗

[Biophysical mechanisms of electromagnetic fields interaction and health effects].

The issue of the biological effect of electromagnetic fields (EMF) has been the subject of interest over one hundred years. Experts in this field agree that exposure to EMF at high levels induce adverse health effects, but their opinions vary on the point whether EMF at levels usually present in the municipal environment and at workposts are also harmful. The expressed doubts apply not only to possible health effects, but also to biophysical mechanisms by which those effects occur. The paper presents these controversies. In general opinion there is as yet no conclusive evidence to consider EMF as a factor harmful to health (may be except the relationship between power frequence magnetic field and some neoplastic diseases, especially leukemia in children). It is also unknown which of biophysical mechanisms may be the underlying reason for possible health effects. All these mean that studies in this area should be continued. A large number of single observations sometimes encourage researchers to intensify their investigations.

Adult↗