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At least 595 records · Page 33Linked to original sources
PubMedDate not supplied

[Modulated electromagnetic field as a factor of selective influence on animal mechanisms of goal-directed behavior].

Proceeding from P.K. Anokhin's theory of the functional systems, the paper considers the action of a modulated electromagnetic field (MEMF) on different stages of the central architectonics of purposeful behaviour of rats: afferent synthesis, decisions making, acceptor of the action results. The action of MEMF was studied in different experimental situations: choice of an alimentary or defensive reaction to one conditioned stimulus in different situations; extinction of conditioned alimentary reactions; elaboration and extinction of alimentary conditioned reactions in animals group contacts; choice of the side of reinforcement in a T-shaped maze, and, lastly, self-stimulation reactions. The experiments have shown that MEMF has a selective effect on the animals' emotional reactions. Greater disturbances are observed in the mechanisms of the animals' appraisal of the action of situational and trigger stimuli or surrounding individuals of their species and, hence, of decisions making and anticipation of future results of the action, the acceptor of the action results.

Agonistic Behavior↗
PubMed1976

[Behavior of reactive shaft pseudarthroses of the canine radius in the electric and electromagnetic fields].

In 27 beagles, 19 radius shaft pseudarthroses and 8 tibia were stimulated either by directly applied alternating current of low frequency and strength, delivered from an implanted battery source, or by a pulsing electromagnetic field inductively coupled to bone. Increase of periosteal callus was only found beneath parallel sling electrodes placed on pseudarthroses parallel to the radius shaft. Stimulation by transverse electrodes implanted into bone produced no significant increase of osteogenesis and bone healing, evaluated by x-rays, scintigrams, and morphometry when compared with contralateral leg controls.

Animals↗
PubMed1999

Electromagnetic-field-induced oscillations of the lipid domain structures in the mixed membranes.

The effect of external electromagnetic field (EMF) on a percolation structure formed during phase separation in the mixed phospholipid membranes was studied by computer simulation. Decay of the percolation structure under electromagnetic radiation was detected. It was shown that oscillation regime can be realized in this system: periodic alternation of formation and decay of the percolation cluster was observed under 10 kHz EMF. The decay of the lipid domain structure in the EMF results from anomalous increase of the permittivity of the continuous fluid lipid phase in the percolation threshold region. It is proposed that detected EMF effect can influence the signal and transport processes associated with percolation properties of biomembranes.

Electromagnetic Fields↗
PubMed1998

Electromagnetic field exposures and childhood cancers in New Zealand.

OBJECTIVES: To assess childhood cancer risks for electromagnetic field (EMF) exposures. METHODS: A case-control study was conducted in New Zealand. Cases (aged from zero to 14 years) were ascertained from national databases including the New Zealand Cancer Registry; 303 took part (participation rate, 88 percent). The 303 age- and gender-matched controls were selected randomly from birth records (participation, 69 percent). Mothers were interviewed about appliance exposures (all cases and controls), and 24-hour residential measurements of EMFs were made (leukemia cases and matched controls). RESULTS: For the various appliance exposures, there were some odds ratios (OR) above 1.0 and others below 1.0. For electric blanket use by the child before diagnosis, the adjusted ORs were: leukemia, 2.2 (95 percent confidence interval [CI] = 0.7-6.4); central nervous system cancers, ORs = 1.6 (CI = 0.4-7.1); and other solid cancers, OR = 2.4 (CI = 1.0-6.1). Leukemia risk was increased for the highest category of the mean measured bedroom magnetic field (> or = 0.2microT cf < 0.1 microT), with an adjusted OR of 15.5 (CI = 1.1-224). A gradient in OR with exposure was not shown (middle category: OR 1.4, CI = 0.3-7.6), and there was no association with exposure categorized into thirds based on controls' exposure. The adjusted OR for leukemia in relation to the measured daytime room magnetic field (> or = 0.2 microT cf < 0.1 microT) was 5.2 (CI = 0.9-30.8). CONCLUSIONS: This was a small study and multiple comparisons were made. The positive findings thus should be interpreted cautiously.

Adolescent↗
PubMed2004

Electromagnetic fields inside a lossy, multilayered spherical head phantom excited by MRI coils: models and methods.

The precise evaluation of electromagnetic field (EMF) distributions inside biological samples is becoming an increasingly important design requirement for high field MRI systems. In evaluating the induced fields caused by magnetic field gradients and RF transmitter coils, a multilayered dielectric spherical head model is proposed to provide a better understanding of electromagnetic interactions when compared to a traditional homogeneous head phantom. This paper presents Debye potential (DP) and Dyadic Green's function (DGF)-based solutions of the EMFs inside a head-sized, stratified sphere with similar radial conductivity and permittivity profiles as a human head. The DP approach is formulated for the symmetric case in which the source is a circular loop carrying a harmonic-formed current over a wide frequency range. The DGF method is developed for generic cases in which the source may be any kind of RF coil whose current distribution can be evaluated using the method of moments. The calculated EMFs can then be used to deduce MRI imaging parameters. The proposed methods, while not representing the full complexity of a head model, offer advantages in rapid prototyping as the computation times are much lower than a full finite difference time domain calculation using a complex head model. Test examples demonstrate the capability of the proposed models/methods. It is anticipated that this model will be of particular value for high field MRI applications, especially the rapid evaluation of RF resonator (surface and volume coils) and high performance gradient set designs.

Algorithms↗
PubMed1982

[Effect of wide-band modulated electromagnetic fields on the workers of high-frequency telephone exchanges].

Physiological examinations of 63 subjects were performed as well as clinical, functional, paraclinical, etc. examinations of 82 subjects working under the effect of wide-band modulated electromagnetic fields in HFA of telephone exchanges. Some physiological changes were found as regards the level of blood pressure and auditory threshold. Though the intensity of EMF were within the allowable limits, changes in the neuro-vegetological state, genital sphere, were found in some of the examined workers as well as in immunologic reactivity and some paraclinical indices, described to develop under electromagnetic effect, attributed to the specificity of EMF-wide-band, modulated.

Adult↗
PubMed2005

Influence of electromagnetic fields on function of automated external defibrillators.

OBJECTIVES: In this study, the authors tested whether electromagnetic interference (EMI) is able to impair correct electrocardiogram analysis and produce false-positive shock advice from automated external defibrillators (AEDs) when the true rhythm is sinus. METHODS: Nineteen healthy subjects were used to test five AEDs available on the Austrian market in a prospective, open, and sequence-randomized study. The primary outcome variable was the absolute number of shocks advised in the presence of EMI. The secondary outcome was the number of impaired analyses caused by incorrectly detected patient movements or electrode failure. RESULTS: Of 760 tests run, 18 (2.37%) cases of false-positive results occurred, and two of five AEDs recommended shocks in the presence of sinus rhythm. Of 760 tests run, no electrode failures occurred. There were 27 occurrences (3.55%) of motion detected by an AED in the presence of strong electromagnetic fields. CONCLUSIONS: AED models differ in their response to EMI; it may be useful to consider specific safety requirements for areas with such fields present. Working personnel and emergency medical services staff should be informed about potential risks and the possible need for patient evacuation before AEDs are attached and shock recommendations are followed.

Adult↗
PubMed1992

Lymphocytes and low-frequency electromagnetic fields.

Human lymphocytes have been used by several researchers to investigate the biological effect of electromagnetic fields (EMF). EMF modulate the response by lymphocytes to lectin stimulation. The size and direction of the effect depends both on the lymphocyte physiology and on the physical parameters characterizing the EMF. Lymphocytes have also been used to investigate the genotoxicity of EMF exposure.

Electromagnetic Fields↗
PubMed1998

A study of the effects of pulsed electromagnetic field therapy with respect to serological grouping in rheumatoid arthritis.

The positive role of pulsed electromagnetic field (PEMF) therapy in rheumatoid arthritis (RA) is known. The differential role of serological status of patients in RA is also well known. This paper presents a study of the differential effects of PEMF therapy on the two serological groups of patients. The responses of the seropositive patients are found to be more subdued. Varying effects of the therapy in alleviating the different symptomatologies indicate that the rheumatoid factor (RF) is more resistant to PEMF.

Adolescent↗
PubMedDate not supplied

[The correction of hypoxic damage to the pulmonary surfactant system of rats with extremely high-frequency electromagnetic fields].

54 white rats were studied physically, histochemically and morphometrically for the effect of EHF electromagnetic field on repair of the lung surfactant system. The damage was inflicted by acute hypoxia existing at the altitude of 9000 m above the sea level simulated in the chamber. For the period studied natural repair was unable to secure the return to normal structure and function of the surfactant system, whereas daily 20-minute exposures to millimetric waves on the chest stimulated repair on after-exposure day 1-5 and provided normalization of all the physical and morphometric parameters.

Acute Disease↗
PubMed1994

Exposure to power-frequency electromagnetic fields in Denmark.

OBJECTIVES: The purpose of the study was to assess exposure to power-frequency electromagnetic fields in various groups with normal or high exposure in occupational and residential environments. METHODS: Exposure to power-frequency (50 Hz) electric and magnetic fields was measured for 301 volunteers (396 measurements) in periods of 24 h in both occupational and residential environments. The study included electrical utility workers (generation, transmission, distribution, substation), office and industrial workers, and people living near high-power transmission lines. Electric and magnetic fields were measured with personal dosemeters, and the mean values were calculated for work and nonwork periods. RESULTS: The work-period magnetic field exposure, as the geometric mean of the distribution of the work-period means, for a group of selected industrial workers with high exposure was 6 [geometric standard deviation (GSD) 4.6] muT. The exposure level was 0.10 (GSD 2.4) muT for "normal" industrial workers and 0.09 (GSD 1.8) muT for office workers. For electrical utility workers the corresponding values were 0.72 (GSD 2.5) muT for substation workers, 0.52 (GSD 4.2) muT for generation workers, 0.36 (GSD 3.5) muT for transmission workers, and 0.15 (GSD 2.9) muT for distribution workers. The magnetic field exposure in normal residences was 0.04 (GSD 2.1) muT, and in residences near high-power lines it was 0.29 (GSD 2.8)muT. Corresponding results on exposure to electric fields are given in the study. CONCLUSIONS: All of the measurements of exposure to electric and magnetic fields were below the values normally used as guidelines.

Denmark↗
PubMed2004

Exposure to extremely low-frequency electromagnetic fields improves social recognition in male rats.

The effect of exposure to low-frequency electromagnetic fields (ELF EMFs) on social recognition was studied. The test was based upon a comparison between two encounters of an adult rat and a conspecific juvenile, separated by an interexposure interval (IEI). The exposure to ELF EMF of 1 mT intensity during 2 h for 9 days increased the duration of short-term memory of adult male Wistar rats up to 300 min. These data indicate, for the first time, that ELF EMF improves social recognition memory in rats.

Animals↗
PubMed1990

[Occupational exposure to electromagnetic fields of extremely low frequency (with particular regard to power plants) and the health status of workers, based on a literature review].

Recently a number of studies were carried on concerning malignant neoplasms, mainly leukemia, in workers exposed to electromagnetic fields. The studies focused upon power industry workers operating transmission--distribution lines, power stations, transformer stations and distribution substations which work at power--line frequencies. A review of selected literature was prepared concentrating on the methods describing conditions of exposure to e-m ELF fields as well as on the results of epidemiological studies. Also, the results of experiments carried on in Poland based on materials accessible only to a compact group of power industry experts were presented.

Electromagnetic Fields↗