Extremely Low Frequency Research Articles

Increase in Blood Levels of Growth Factors Involved in the Neuroplasticity Process by Using an Extremely Low Frequency Electromagnetic Field in Post-stroke Patients.

Background: Neuroplasticity ensures the improvement of functional status in patients after stroke. The aim of this study was to evaluate the effect of extremely low-frequency electromagnetic field therapy (ELF-EMF) on brain plasticity in the rehabilitation of patients after stroke.Methods: Forty-eight patients were divided into two groups underwent the same rehabilitation program, but in the study group, the patients additionally were exposed to a standard series of 10 ELF-EMF treatments. To determine the level of neuroplasticity, we measured the plasma level of the brain-derived neurotrophic factor (BDNF), the vascular-endothelial growth factor, as well as BDNF mRNA expression. Additionally, we determined the molecule levels for hepatocyte growth factor, stem cell factor, stromal cell-derived factor 1α, nerve growth factor β, and leukemia inhibitory factor, using 5plex cytokine panel in plasma. After 4 weeks, during which patients had undergone neurorehabilitation and neurological examinations, we assessed functional recovery using the Barthel Index, Mini-Mental State Examination (MMSE), Geriatric Depression Scale, National Institutes of Health Stroke Scale (NIHSS), and the modified Rankin Scale (mRS).Results: We observed that ELF-EMF significantly increased growth factors and cytokine levels involved in neuroplasticity, as well as promoted an enhancement of functional recovery in post-stroke patients. Additionally, we presented evidence that these effects could be related to the increase of gene expression on the mRNA level. Moreover, a change of BDNF plasma level was positively correlated with the Barthel Index, MMSE, and negatively correlated with GDS.Conclusion: Extremely low-frequency electromagnetic field therapy improves the effectiveness of rehabilitation of post-stroke patients by improving neuroplasticity processes.

Characteristics of Thunderstorm Structure and Lightning Activity Causing Negative and Positive Sprites

AbstractThis paper reports observation of five sprites captured over a mesoscale convective system in a 15‐min window. One of them (11:49 hr sprite) was preceded by a negative cloud‐to‐ground with peak current of −40.9 kA that was detected both by the local lightning detection network (sprite time delay <70–90 ms) and the extremely low frequency (ELF) magnetic field data. Another sprite (11:46 hr sprite) was preceded by a negative stroke (sprite time delay <10 ms) with peak current of −106.6 kA but the ELF signal of the stroke could not be recognized. In addition, no positive strokes were recorded 1.5 min before the 11:46 hr sprite. The rest of the sprites were confirmed as positive both by the local lightning detection network and the ELF magnetic field data. The negative sprite occurred during strong convection, indicated by the increase of the area of the thundercloud with radar echo top of 8–11, 9–11, and 6–12 km. The strong convection and large wind shear in the thunderstorm middle and upper region provide favorable conditions to produce the parent cloud‐to‐ground lightning discharges of the negative sprites.

Effect of extremely low frequency electromagnetic field exposure on pachytene spermatocyte cell quantity in Webster strain male mice

Many electronic devices that are used in daily life can produce an extremely low frequency (ELF) electromagnetic field that may disturb human reproductive organs. Several studies have shown disturbances in spermatogenesis, which decreases sperm production. We aimed to determine the accumulative effect of exposure to a low frequency magnetic field on pachytene spermatocyte cells in mice. The cells were exposed to electromagnetic fields of 0 kV (control), 3 kV/10 cm 5.5 μT (Group 1), 4 kV/10 cm 5.4 μT (Group 2), and 5 kV/10 cm 5.3 μT (Group 3) in first (F1), second (F2), and third (F3) generation mice. The cell number decreased in all exposure Groups compared to the control Group (P < 0.05). Group 1 exposure had no accumulative effects on any generation (P > 0.05). Group 2 exposure showed an accumulative effect on the F1 and F2 generations, while Group 3 exposure had an accumulative effect on F2 and F3 generations. Moreover, for all three groups, exposure was correlated with proportional decrease in cell number. ELF electromagnetic field exposure caused decreased pachytene spermatocyte cell numbers and had an accumulative effect on each generation.

Impact of the Ionospheric Day–Night Non-Uniformity on the ELF Radio-Wave Propagation

The real structure of the lower ionosphere should be taken into account when propagation of extremely low frequency (ELF) radio waves is modeled and the global electromagnetic (Schumann) resonance in the Earth–ionosphere cavity is studied. In the present work, we use a 2D telegraph equation (2DTE) to estimate the effect of the ionospheric day–night non-uniformity on the electromagnetic field amplitude at the Schumann-resonance and higher frequencies. The properties of the cavity are accounted for by using the full wave solution technique through conductivity profiles in the daytime and night-time conditions. Electromagnetic fields in the non-uniform cavity are found by using a 2DTE. Both the sharp terminator model and the model of a smooth day–night transition were considered. The main attention was focused on effects arising on 5000-km paths that are perpendicular or parallel to the solar terminator line. The data were computed for a series of frequencies. A comparison of the calculated data with observation results is also performed and an interpretation of the observed effects is given.

A 60 Hz uniform electromagnetic field promotes human cell proliferation by decreasing intracellular reactive oxygen species levels.

Previously, we showed that exposure of human normal and cancer cells to a 6 mT, 60 Hz gradient electromagnetic field (EMF) induced genotoxicity. Here, we investigated the cellular effects of a uniform EMF. Single or repetitive exposure to a 6 mT, 60 Hz uniform EMF neither induced DNA damage nor affected cell viability in HeLa and primary IMR-90 fibroblasts. However, continuous exposure of these cells to an EMF promoted cell proliferation. Cell viability increased 24.4% for HeLa and 15.2% for IMR-90 cells after a total 168 h exposure by subculture. This increase in cell proliferation was directly correlated with EMF strength and exposure time. When further incubated without EMF, cell proliferation slowed down to that of unexposed cells, suggesting that the proliferative effect is reversible. The expression of cell cycle markers increased in cells continuously exposed to an EMF as expected, but the distribution of cells in each stage of the cell cycle did not change. Notably, intracellular reactive oxygen species levels decreased and phosphorylation of Akt and Erk1/2 increased in cells exposed to an EMF, suggesting that reduced levels of intracellular reactive oxygen species play a role in increased proliferation. These results demonstrate that EMF uniformity at an extremely low frequency (ELF) is an important factor in the cellular effects of ELF-EMF.

Muscle Extremely Low Frequency Magnetic Stimulation Eliminates the Effect of Fatigue on EEG-EMG Coherence during the Lateral Raise Task: A Pilot Quantitative Investigation.

The aim of this study was to quantitatively investigate the effects of force load, muscle fatigue, and extremely low frequency (ELF) magnetic stimulation on electroencephalography- (EEG-) electromyography (EMG) coherence during right arm lateral raise task. Eighteen healthy male subjects were recruited. EEG and EMG signals were simultaneously recorded from each subject while three different loads (0, 1, and 3kg) were added on the forearm. ELF magnetic stimulation was applied to the subject's deltoid muscle between tasks during the resting period. Univariate ANOVA showed that all EEG-EMG coherence areas of C3, C4, CP5, and CP6 were not significantly affected by the force load (all p>0.05) and that muscle fatigue led to statistically significant reductions on the coherence area of gamma band in C3 (p=0.014) and CP5 (p=0.019). More interestingly, these statistically significant reductions disappeared with the application of muscle ELF magnetic stimulation, indicating its potential application to eliminate the effect of fatigue.

A New Approximate Method for Lightning-Radiated ELF/VLF Ground Wave Propagation over Intermediate Ranges

A new approximate method for lightning-radiated extremely low-frequency (ELF) and very low-frequency (VLF) ground wave propagation over intermediate ranges is presented in this paper. In our approximate method, the original field attenuation function is divided into two factors in frequency domain representing the propagation effect of the ground conductivity and Earth’s curvature, and both of them have clearer formulations and can more easily be calculated rather than solving a complex differential equation related to Airy functions. The comparison results show that our new approximate method can predict the lightning-radiated field peak value over the intermediate range with a satisfactory accuracy within maximum errors of 0.0%, −3.3%, and −8.7% for the earth conductivity of 4 S/m, 0.01 S/m, and 0.001 S/m, respectively. We also find that Earth’s curvature has much more effect on the field propagation at the intermediate ranges than the finite ground conductivity, and the lightning-radiated ELF/VLF electric field peak value (V/m) at the intermediate ranges yields a propagation distance d (km) dependence of d−1.32.

Radiation from Visual Display Unit

The radiation from different types of Visual Display Units (VDU) (that is, Liquid Crystal Display (LCD) and Cathode Ray Tube (CRT)), projector and interactive screen were examined using a Cell Sensor Extremely Low Frequency (ELF) detection meter. The study revealed that ELF radiation in CRT VDUs is eight (8) times greater than in LCD VDUs. The mean ELF obtained from interactive screen at 30 cm was 1.6 mG and 1.9 mG at start-up and after 3 hours of use respectively with a mean value of 1.03 mG for a distance of 100 cm at start up. The mean ELF radiation from the projector screen at a distance of 10 cm is 0 mG, while that of interactive screen is 2.4 mG at the same distance. Thus, the study suggested that, projector and screen is better than interactive screen when making presentation considering the closeness of user to the interactive screen throughout the course of presentation.

Shielding a high-sensitivity digital detector from electromagnetic interference.

PurposeTo document a study in shielding a high‐sensitivity digital mammography system detector from AC magnetic fields of magnitudes great enough to induce imaging artifacts.Methods/materialsPreliminary evaluation of AC magnetic fields at a site designated for a digital breast tomosynthesis (DBT) system raised concerns that the magnetic component of electromagnetic interference (EMI) may be great enough to induce imaging artifacts. Subsequent measurements using digital detector arrays from two separate manufacturers verified this concern, and AC magnetic fields were mapped, spatially and temporally, throughout the area of concern. A simple shielding model was developed to elucidate the physics of extremely low‐frequency (ELF) EMI shielding and independently verify a commercial group's proposed shielding design and installation. Postshielding measurements were performed to demonstrate that the EMI fields were reduced to acceptable levels.ResultsPreshielding measurements showed AC magnetic fields significantly exceeding manufacturers’ tolerances for artifact‐free imaging in DBT. Continuous measurements demonstrated that the EMI fields varied significantly over time. Some locations in the room routinely averaged above 30 mG and occasionally exceeded 100 mG. The source was attributed to an adjacent electrical supply room, and temporal changes of the EMI were attributed to variations of the building electrical loads. The proposed shielding primarily consisted of continuous aluminum (6.35 mm thickness) and was installed by a group specializing in electromagnetic field shielding. Postshielding measurements demonstrated that the EMI fields were significantly reduced, generally to less than 0.5 mG, and that the shielding effectively dampened the large variations due to dynamic building electrical loads. Subsequent installation and evaluation of a DBT system revealed no issues with imaging artifacts.ConclusionsThe successful shielding of ELF EMI involves physical principles that are not commonly encountered by medical physicists. Modern high‐sensitivity digital detectors may be successfully shielded against imaging artifacts with careful application of these principles.

Effect of Ionosphere on the Excitation of Electromagnetic Field at Extremely Low and Lower Frequencies in the Near-Field Zone

Excitation of electromagnetic fields at extremely low and lower frequencies in the near-field zone of the Earth–ionosphere waveguide is considered. Variations in the field amplitude in the lower part of the extremely low frequency (ELF) range and lower frequencies are experimentally determined under different geophysical conditions in the absence of variations in the ultralow frequency (ULF) range. The effects related to such variations are analyzed with the aid of theoretical calculations that show significant effect of ionosphere in the near-field zone at relatively low terrestrial conduction.

Excitation of electromagnetic whistler waves due to a parametric interaction between magnetosonic and lower oblique resonance modes in a cold, magnetized plasma

We have studied the parametric interaction between a fast magnetosonic (FM) mode and a lower oblique resonance (LOR) mode in a cold, magnetized plasma using a kinetic, three dimensional Particle-in-Cell simulation code called the Large Scale Plasma. The FM mode is excited with a loop antenna driven at a frequency below the lower hybrid frequency (ωLH), while the LOR is excited at a frequency above ωLH. For historical purposes explained in the Introduction, we call the antennas which drive the FM mode and LOR mode Extremely Low Frequency (ELF) and Very Low Frequency (VLF) antennas, respectively. The antennas are modeled as magnetic dipoles (ρant = 0) and are assigned a time varying current density within a finite sized current loop. The VLF and ELF antennas are driven at 10 A and 3 A, respectively. The parametric interaction is excited with a combined ELF/VLF antenna (which we call a parametric antenna) and includes both antennas driven simultaneously in the same simulation domain. We show that the parametric antenna non-linearly excites electromagnetic (EM) whistler waves to a greater extent than the VLF antenna alone. We also show that the parametric excitation of EM whistler waves leads to greater emitted EM power (measured in Watts) compared with a VLF antenna alone.

Magnetocarcinogenesis: is there a mechanism for carcinogenic effects of weak magnetic fields?

Extremely low-frequency (ELF) magnetic fields have been classified as possibly carcinogenic, mainly based on rather consistent epidemiological findings suggesting a link between childhood leukaemia and 50-60 Hz magnetic fields from power lines. However, causality is not the only possible explanation for the epidemiological associations, as animal and in vitro experiments have provided only limited support for carcinogenic effects of ELF magnetic fields. Importantly, there is no generally accepted biophysical mechanism that could explain such effects. In this review, we discuss the possibility that carcinogenic effects are based on the radical pair mechanism (RPM), which seems to be involved in magnetoreception in birds and certain other animals, allowing navigation in the geomagnetic field. We review the current understanding of the RPM in magnetoreception, and discuss cryptochromes as the putative magnetosensitive molecules and their possible links to cancer-relevant biological processes. We then propose a hypothesis for explaining the link between ELF fields and childhood leukaemia, discuss the strengths and weaknesses of the current evidence, and make proposals for further research.

The antitumor effect of static and extremely low frequency magnetic fields against nephroblastoma and neuroblastoma.

Certain magnetic fields (MF) have potential therapeutic antitumor effect whereas the underlying mechanism remains undefined. In this study, a well-characterized MF was applied to two common childhood malignancies, nephroblastoma and neuroblastoma. This MF has a time-averaged total intensity of 5.1 militesla (mT), and was generated as a superimposition of a static and an extremely low frequency (ELF) MF in 50 Hertz (Hz). In nephroblastoma and neuroblastoma cell lines including G401, CHLA255, and N2a, after MF exposure of 2 h per day, the cell viability decreased significantly after 2 days. After 3 days, inhibition rates of 17-22% were achieved in these cell lines. Furthermore, the inhibition rate was positively associated with exposure time. On the other hand, when using static MF only while maintaining the same time-averaged intensity of 5.1 mT, the inhibition rate was decreased. Thus, both time and combination of ELF field were positively associated with the inhibitory effect of this MF. Exposure to the field decreased cell proliferation and induced apoptosis. Combinational use of MF together with chemotherapeutics cisplatin (DDP) was performed in both in vitro and in vivo experiments. In cell lines, combinational treatment further increased the inhibition rate compared with single use of either DDP or MF. In G401 nephroblastoma tumor model in nude mice, combination of MF and DDP resulted in significant decrease of tumor mass, and the side effect was limited in mild liver injury. MF exposure by itself did not hamper liver or kidney functions. In summary, the antitumor effect of an established MF against neuroblastoma and nephroblastoma is reported, and this field has the potential to be used in combination with DDP to achieve increased efficacy and reduce side effects in these two childhood malignancies. Bioelectromagnetics. 39:375-385, 2018. © 2018 Wiley Periodicals, Inc.

Approximated Solutions for ELF Near-Field Propagation Due to a Horizontal Electric Dipole Excitation Near the Sea-Rock Boundary

In this paper, the near-field propagation of extremely low frequency (ELF) wave due to a horizontal electric dipole excitation has been investigated near the boundary between two dielectrics. First, a novel quasi-static approximation is assumed with $\gamma _{2}\approx -i\lambda $ so that the integrands of the Fourier–Bessel representations for ELF field are approximated near the poles by adopting Maclaurin’s Expansion. Second, by the conditions of $k_{2}\rho \ll 1$ , $\textit {z} / {\rho \ll 1}$ , and $d / \rho \ll 1$ , the ratio of wave numbers for rock and sea $k_{2} /k_{1}$ is equivalent to an infinitesimal that only fundamental terms of $| k_{2}^{2}\gamma _{2} |/ | k_{1}^{2}\gamma _{1} |$ are reserved for the electromagnetic components. Third, the approximated formulas are derived for ELF near-field propagation generated by a horizontal electric dipole with the above simplifications. Finally, the simplified formulas are verified by an analogy with the exact and approximated formulas, respectively. It demonstrates that the proposed formulas are complementarily essential for evaluations of ELF near field and the plotted Poynting vectors indicate approximately the propagation direction of the energy flow.

ELF Whistler Dependence on a Sunlit Ionosphere

AbstractNarrow bandwidth, whistler‐like spectral features in the extremely low frequency (ELF) range were recorded at South Pole Station over the duration of 2004. A full year of observation shows a distinct lack of activity over the Antarctic winter season. A calculation of solar zenith angle at the time of detection illustrates a connection between the occurrence of ELF whistlers and a sunlit ionosphere. ELF whistlers detected at low latitude follow a similar general trend between ELF whistler occurrence rate and changing solar zenith angle, but with an additional persistence of detections after local sunset. Temporal profiles from the International Reference Ionosphere 2016 show that the peaks in ELF whistler occurrence align with times of changing ionospheric composition. Correlation with solar activity per the F10.7 index shows no connection to daily variations in activity, and the consistency of solar flux levels throughout 2004 appears insufficient to explain the absence of events during the winter blackout. These observations place new physical constraints on the conditions necessary for detecting ELF whistlers and suggest the potential for localized generating mechanisms due to plasma instabilities in the ionosphere.

Lunisolar Tides Influence on Electrical Conductivity of the Earth’s Crust in the Territory of Kola Peninsula

The results of studying the influence of lunisolar tides on the electrical conductivity of the Earth’s crust in the territory of the Kola Peninsula are presented. Along with the results obtained by the authors, the data of other researchers are also considered. All the studies are based on the analysis of the field produced by the Zevs facility transmitting extremely low frequency (ELF) signals at 82–83 Hz. The measurements were carried out in different years at the Avva-Guba (1998), Lovozero (2009), and Imandra–Varzuga polygon (IVP) monitoring sites (2013) located 180, 90, and 160 km from the transmitter, respectively. The negative correlation between the tides and crustal electrical resistivity is revealed at all the points. This means that tidal rises of the Earth’s surface are accompanied by a decrease in resistivity and vice versa. The overview shows that the higher the resistivity of separate Earth’s crustal blocks the higher the relative amplitudes of the corresponding tidal responses that are observed.

Beneficial effects of Extremely Low Frequency (ELF) Sinusoidal magnetic field (SMF) exposure on mineral and protein content of mungbean seeds and sprout.

ive mungbean [Vigna radiata (L.) Wilczek] lines (CN9-5, EC693363, Harsha, KPS-1 and NM 94) were subjected to three different Extremely Low Frequency (ELF) sinusoidal magnetic field (SMF) treatments. Fresh seed lots were exposed to ELF-SMF for 5 hours/day for a total duration of 15 days. Three treatment combinations of ELF-SMF chosen for assessment and comparison were: T1-10Hz, 1500 + 250 nanoTesla (nT), T2- 50Hz, 1500 + 250nT and T3 - 100Hz, 1500 + 250nT. Non-treated seeds were maintained as control (T4). Minerals (iron, calcium, zinc and total phosphorus) and protein contents were determined in both the control and test seed lots and sprout samples raised from them. The sprouting parameters were also recorded. All three ELF-SMF treatments were significant for calcium and total phosphorus content in the test seed samples when compared to control. In the case of sprouts, with respect to minerals, all the ELF-SMF treatments were significant for calcium content when compared to control. With respect to protein, sprouts from EC 693363 line recorded 8.3% increase in protein content in T1 (10Hz) while sprouts from Harsha line recorded 7.2% increase in protein content in T2 (50Hz) compared to their respective controls. No treatment effects were observed for the sprouting parameters

Immune-Modulating Perspectives for Low Frequency Electromagnetic Fields in Innate Immunity.

In recent years, the effects of electromagnetic fields (EMFs) on the immune system have received a considerable interest, not only to investigate possible negative health impact but also to explore the possibility to favorably modulate immune responses. To generate beneficial responses, the immune system should eradicate pathogens while “respecting” the organism and tolerating irrelevant antigens. According to the current view, damage-associated molecules released by infected or injured cells, or secreted by innate immune cells generate danger signals activating an immune response. These signals are also relevant to the subsequent activation of homeostatic mechanisms that control the immune response in pro- or anti-inflammatory reactions, a feature that allows modulation by therapeutic treatments. In the present review, we describe and discuss the effects of extremely low frequency (ELF)-EMF and pulsed EMF on cell signals and factors relevant to the activation of danger signals and innate immunity cells. By discussing the EMF modulating effects on cell functions, we envisage the use of EMF as a therapeutic agent to regulate immune responses associated with wound healing.

Meeting the imperative to accelerate environmental bioelectromagnetics research

In this article, the author draws on his experience in the world of geospatial information technology standards to suggest a path toward acceleration of bioelectromagnetics science. Many studies show biological effects of extremely low frequency (ELF) and radiofrequency (RF) radiation despite that fact that the radiation is too weak to cause temperature changes in biological features. Considered together in worst case scenarios, such effects, many of which appear to have long latencies, could have potentially disastrous consequences for the health and safety of humans and wildlife. Other studies show no such effects, and in both cases, often there are significant research quality deficits that make it difficult to draw firm conclusions from the data. The progress of bioelectromagnetics science is retarded by a lack of standard data models and experimental protocols that could improve the overall quality of research and make it easier for researchers to benefit from omics-related bioinformatics resources. "Certainty of safety" of wireless devices used in digital communications and remote sensing (radar) is impossible without dosimetry standards that reflect the effects of non-thermal exposures. Electrical signaling in biological systems, a poorly funded research domain, is as biologically important as chemical signaling, a richly funded research domain, and these two types of signaling are inextricably connected. Entreprenuerial scientists pursuing bioelectronic innovations have begun to attract new funding. With appropriate institutional coordination, this new funding could equally benefit those investigating environmental effects of ELF and RF radiation. The author proposes a concerted effort among both bioelectronics technology stakeholders and environmental bioelectromagnetics science researchers to collaborate in developing institutional arrangements and standard data models that would give the science a stronger bioinformatics platform and give researchers better access to omics data. What is proposed here is essentially a bioelectromagnetics omics initiative.

MiR200 and miR302: Two Big Families Influencing Stem Cell Behavior.

In this review, we described different factors that modulate pluripotency in stem cells, in particular we aimed at following the steps of two large families of miRNAs: the miR-200 family and the miR-302 family. We analyzed some factors tuning stem cells behavior as TGF-β, which plays a pivotal role in pluripotency inhibition together with specific miRNAs, reactive oxygen species (ROS), but also hypoxia, and physical stimuli, such as ad hoc conveyed electromagnetic fields. TGF-β plays a crucial role in the suppression of pluripotency thus influencing the achievement of a specific phenotype. ROS concentration can modulate TGF-β activation that in turns down regulates miR-200 and miR-302. These two miRNAs are usually requested to maintain pluripotency, while they are down-regulated during the acquirement of a specific cellular phenotype. Moreover, also physical stimuli, such as extremely-low frequency electromagnetic fields or high-frequency electromagnetic fields conveyed with a radioelectric asymmetric conveyer (REAC), and hypoxia can deeply influence stem cell behavior by inducing the appearance of specific phenotypes, as well as a direct reprogramming of somatic cells. Unraveling the molecular mechanisms underlying the complex interplay between externally applied stimuli and epigenetic events could disclose novel target molecules to commit stem cell fate.