What does low frequency magnetic fields mean? Influence of low-frequency electromagnetic radiation on living organisms

About EMP in fault zones:

It is noted that “above the surface layer of zones of active geological faults, elevated level natural impulse electro magnetic field even outside of the perceptible seismicity ", due, most likely, to a change in the conditions of passage of atmospherics (in the ionosphere) over zones of active faults." Earth's crust it is divided by deep faults (general crustal faults) into separate blocks, close to rectangular in shape. The width of the deep fault zones is hundreds of meters - tens of kilometers, the length is tens, hundreds and the first thousand kilometers. On the the earth's surface ruptured tectonic faults are represented by zones with a large number of cracks of various nature (crushing zones).

Shown is a geoelectric section of a crushing zone with a low resistance r in the range of 200 - 1000 Ohm m and a width of ~ 50 m (Ulan - Burgasy ridge, Baikal rift zone)

Let us consider in more detail the problem of ground wave propagation over multi-focal impedance radio paths passing over fault zones. Let the receiver of seismoelectromagnetic emissions be located in the middle of the fault region. The radiation source can have any azimuth relative to the receiver and the axis of the fault. The path of propagation of electromagnetic waves can pass: a) across the axis of the fault; b) at an arbitrary angle relative to the axis of the fault; c) along the axis of the fault. With respect to the Fresnel zone, these situations are as follows

Possible types of 2D impedance radio paths over fault zones. δ1, δ2 - surface impedances of the "piece" of the path, T - transmitter, R - receiver, L - width of the fault, l - length of the radio path

Since the fault zone usually has a high conductivity relative to the surrounding rocks, σ fracture. >> σamb. rocks, then there is a "leakage" of energy from the upper part of the distribution area to the bottom area (diffusion along wave fronts). Numerical calculations for a model path in the range of 2 - 1000 kHz show a pronounced enhancement of the field in the fault zone - the "recovery" effect.

Attenuation function modulus in the range 2 - 1000 kHz (Section 1: ρ = 100 Ohm m, ε = 20; section 2: ρ = 3000 Ohm m, ε = 10; section 3: ρ = 1 ÷ 50 Ohm m, ε = 20)

The "recovery" effect is enhanced up to 3.8 times with an increase in the frequency from 2 to 1000 kHz, while the relative increase in the field very weakly depends on the resistance of the fault. Variations of r within 1 ÷ 50 Ohm · m practically do not change the ratio | W | 160 km / | W | 150 km and the course of the spectral characteristics of the impedance channel. Thus, the increased level of the natural pulsed electromagnetic field observed in many fault zones is explained not by increased radiation from the fault zone, but by the influence of the "landing" site, which has a high conductivity ...

"Characteristics of the Earth's natural pulsed electromagnetic field in the VLF range"; I.B. Naguslaeva, Yu.B. Bashkuev

You can immediately recall the coastal effect of the aurora borealis ...

About weak and superweak effects, a little - but interesting:

For 24 days, rats sensitized to the action of EMF were exposed to an alternating magnetic field with a very complex pattern of variations every day at about midnight; average values ​​of induction were in the range of 20-500 nanotesla; when observing the behavior of animals, the number of different behavioral acts, including aggression, was systematically recorded.

The processing of the measurements allowed the authors to draw the following conclusion: group aggression of rats can be enhanced or weakened by the action of EMF, depending on some of their morphological and dynamic characteristics. The same authors found in similar experimental animals an increase in acts of aggression with an increase in geomagnetic disturbance ...

As already noted, the magnetic component of the electromagnetic variations of the habitat is a very penetrating agent - it freely penetrates under kilometers rocks, permeates all biological tissues. Therefore, it is possible to directly influence the low-frequency EMFs on the embryo, which, it would seem, is reliably protected by a homeostat from environmental influences. Already the very first simplest attempts to study the effect of EMF variations on embryonic development people gave impressive results ...

There is also an interesting historical aspect of research on the ecological significance of EMFs. Many observations were made in the past (biological precursors of earthquakes - the relationship of biological indicators with changes in the number of sunspots), even in the distant past (biolocation). In each case, for the interpretation of the observations, the existence of a special "radiation" was postulated - in heliobiology they figured for a long time, Z is radiation and X is an agent; meteorological processes were accompanied by “weather radiation” (the indicator was “bacteria), and“ orgone energy ”or“ microlepton gas ”was released from the soil.

Does "space weather" affect social life?

Zeeman resonance absorption is not the only way to influence the spin state. Another way follows from the property of a constant magnetic field to suppress the triplet-singlet conversion and, thus, to influence the kinetics of the spin-dependent process. Low-frequency EMF, kilometer and longer waves, fast processes (<10"сек) воспринимаются как квази-постоянные поля и могут влиять на них по механизму подавления триплет-синглетной конверсии

Convincing evidence of the leading role of the spin state was obtained in studies of the physics of crystal plasticity. They showed that EMFs, 5-7 orders of magnitude weaker than kT, increase plasticity in spite of equilibrium thermodynamics. The mechanism of the effect, called magnetoplastic, is as follows: the displacement of dislocations to the neighboring Peierls valley, initiated by the paramagnetic state of the dislocation core, occurs in a time shorter than the time of spin relaxation of dislocations. The source of energy for such breakthroughs is mechanical stresses, which are always present in crystals. The role of EMF here is reduced to the suppression of the triplet-singlet conversion of paramagnetic pairs, which increases the lifetime of dislocation nuclei in the paramagnetic state and, accordingly, increases the chance of dislocation of a dislocation by one more elementary step.

Basic requirements for materials. In addition to high magnetic permeability and low coercive force, soft magnetic materials must have a high saturation induction, i.e. to pass the maximum magnetic flux through a given cross-sectional area of ​​the magnetic circuit. Fulfillment of this requirement makes it possible to reduce the overall dimensions and weight of the magnetic system.

Magnetic material used in alternating fields should have, possibly, lower magnetization reversal losses, which consist mainly of hysteresis and eddy current losses.

To reduce eddy current losses in transformers, soft magnetic materials with increased resistivity are chosen. Usually magnetic cores are assembled from separate thin sheets isolated from each other. Ribbon cores wound from thin tape with interturn insulation made of dielectric varnish are widely used. The requirement of high plasticity is imposed on sheet and strip materials, due to which the process of manufacturing products from them is facilitated.

An important requirement for soft magnetic materials is to ensure the stability of their properties, both in time and in relation to external influences, such as temperature and mechanical stress. Of all the magnetic characteristics, the greatest changes during the operation of the material are the magnetic permeability (especially in weak fields) and the coercive force.

Ferrites.

As noted above, ferrites are oxide magnetic materials in which spontaneous domain magnetization is due to uncompensated antiferromagnetism.

High resistivity, exceeding the resistivity of iron by 10 3 -10 13 times, and, consequently, relatively insignificant energy losses in the region of high and high frequencies, along with sufficiently high magnetic properties, provide ferrites with widespread use in radio electronics.

Number	Name	Ferrite grade
group	group	Ni-Zn	Mn-Zn
I	General application	100NN, 400NN, 400NN1, 600NN, 1000NN, 2000NN	1000NM, 1500NM, 2000NM, 3000NM
II	Thermostable	7VN, 20VN, 30VN, 50VN, 100VN, 150VN	700NM, 1000NM3, 1500NM1, 1500NM3, 2000NM1, 2000NM3
III	Highly permeable		4000NM, 6000NM, 6000NM1, 10000NM, 20000NM
IV	For television equipment		2500NMS1, 3000NMS
V	For pulse transformers	300NNI, 300NNI1, 350NNI, 450NNI, 1000NNI, 1100NNI	1100NMI
VI	For tunable paths	10VNP, 35VNP, 55VNP, 60VNP, 65VNP, 90VNP, 150VNP, 200VNP, 300VNP
Vii	For broadband transformers	50VNS, 90VNS, 200VNS, 300VNS
VIII	For magnetic heads	500NT, 500NT1, 1000NT, 1000NT1, 2000NT	500MT, 1000MT, 2000MT, 5000MT
IX	For temperature sensors	1200NN, 1200NN1, 1200NN2, 1200NN3, 800NN
X	For magnetic shielding	200VNRP, 800VNRP

Tab. 2 Groups and brands of soft magnetic ferrites.

Highly permeable ferrites. Nickel-zinc and manganese-zinc ferrites are most widely used as soft magnetic materials. They crystallize in the spinel structure and are substitutional solid solutions formed by two simple ferrites, one of which (NiFe 2 O 4 or MnFe2O4) is ferrimagnet, and the other (ZnFe 2 O 4) is nonmagnetic. The main regularities of changes in the magnetic properties of the composition in such systems are shown in Figs. 2 and 3. To explain the observed regularities, it is necessary to take into account that zinc cations in the spinel structure always occupy tetrahedral oxygen interstices, and ferric cations can be located both in tetra- , and in octahedral spaces. The composition of the solid solution, taking into account the distribution

cations by oxygen interstices can be characterized by the following formula:

(Zn 2+ x Fe 3+ 1-x) O 4

where the arrows conventionally indicate the direction of the magnetic moments of the ions in the corresponding sublattices. Hence, it can be seen that the entry of zinc into the crystal lattice is accompanied by the displacement of iron into octahedral positions. Accordingly, the magnetization of the tetrahedral (A) sublattice decreases and the degree of compensation for the magnetic moments of the cations located in different sublattices (A and B) decreases. As a result, a very interesting effect arises: an increase in the concentration of the nonmagnetic component leads to an increase in the saturation magnetization (and, consequently, Bs) of the solid solution (Fig. 2). However, the dilution of the solid solution with nonmagnetic ferrite weakens the basic exchange interaction of the A-O-B type, which is expressed in a monotonic decrease in the Curie temperature (T c) with an increase in the molar fraction of ZnFe 2 O 4 in the composition of ferrospinel. The rapid drop in the saturation induction in the region x> 0.5 is explained by the fact that the magnetic moments of a small number of ions in the tetrahedral sublattice are no longer able to orient the magnetic moments of all cations in the B sublattice antiparallel to themselves. In other words, the exchange interaction of the A - O - B type becomes so weak that it cannot suppress the competing interaction of the B - O - B type, which is also negative and tends to cause an antiparallel orientation of the magnetic moments of the cations in the B sublattice.

The weakening of the exchange interaction between cations with an increase in the content of the nonmagnetic component leads to a decrease in the constants of crystallographic anisotropy and magnetostriction. This facilitates the magnetization reversal of the ferrimagnet in weak fields, i.e. the initial magnetic permeability increases. Figure 3 gives a clear idea of ​​the dependence of the initial magnetic permeability on the composition of the solid phase. The maximum permeability value corresponds to a point in the composition triangle with approximate coordinates 50% Fe 2 O 3, 15% NiO and 35% ZnO. This point corresponds to the solid solution Ni 1-x Zn x Fe 2 O 4 with x "0.7. From a comparison of Figs. 2 and 3, it can be concluded that ferrites with a high initial magnetic permeability should have a low Curie temperature. Similar patterns are observed for manganese-zinc ferrites.

The values ​​of the initial magnetic permeability and coercive force are determined not only by the composition of the material, but also by its structure. Obstacles hindering the free movement of domain walls when ferrite is exposed to a weak magnetic field are microscopic pores, inclusions of side phases, areas with a defective crystal lattice, etc. Eliminating these structural barriers, which also hinder the magnetization process, can significantly increase the magnetic permeability of the material. The size of the crystal grains has a great influence on the value of the initial magnetic permeability of ferrites. Manganese-zinc ferrites with a coarse-grained structure can have an initial magnetic permeability up to 20,000. This value is close to the initial magnetic permeability of the best grades of permalloy.

Magnetic properties. For ferrites used in alternating fields, in addition to the initial magnetic permeability, one of the most important characteristics is the tangent of the loss angle tgd. Due to the low conductivity, the component of eddy current losses in ferrites is practically small and can be neglected. In weak magnetic fields, hysteresis losses are also insignificant. Therefore, the value of tand in ferrites at high frequencies is mainly determined by magnetic losses due to relaxation and resonance phenomena. To assess the permissible frequency range in which this material can be used, the concept of the critical frequency f cr is introduced. Usually, fcr is understood as a frequency at which tgd reaches a value of 0.1.

The inertia of the displacement of domain walls, which appear at high frequencies, leads not only to an increase in magnetic losses, but also to a decrease in the magnetic permeability of ferrites. The frequency f gr, at which the initial magnetic permeability decreases to 0.7 of its value in a constant magnetic field, is called borderline... As a rule, f cr< f гр. Для сравнительной оценки качества магнитомягких ферритов при заданных значениях H и f удобной характеристикой является относительный тангенс угла потерь, под которым понимают отношение tgd/m н.

Comparison of the magnetic properties of ferrites with the same initial magnetic permeability shows that, in the frequency range up to 1 MHz, manganese-zinc ferrites have a significantly lower relative loss tangent than nickel-zinc ferrites. This is due to the very low hysteresis losses of manganese-zinc ferrites in weak fields. An additional advantage of high permeability manganese-zinc ferrites is increased saturation induction and higher Curie temperature. At the same time, nickel-zinc ferrites have higher resistivity and better frequency properties.

In ferrites, as in ferromagnets, the reversible magnetic permeability can change significantly under the influence of the strength of a constant magnetizing field, and in high-permeability ferrites this dependence is more pronounced than in high-frequency ferrites with a small initial magnetic permeability.

The magnetic properties of ferrites depend on mechanical stresses that can occur during winding, fastening of products and for other reasons. To avoid deterioration of magnetic characteristics, ferrites should be protected from mechanical stress.

Electrical properties... In terms of electrical properties, ferrites belong to the class of semiconductors or even dielectrics. Their electrical conductivity is due to the processes of electronic exchange between ions of variable valence ("hopping" mechanism). The electrons participating in the exchange can be considered as charge carriers, the concentration of which is practically independent of temperature. At the same time, as the temperature rises, the probability of electron hopping between ions of variable valence increases exponentially, i.e. the mobility of charge carriers increases. Therefore, the temperature change in the specific conductivity and resistivity of ferrites with an accuracy sufficient for practical purposes can be described by the following formulas:

g = g 0 exp [-E 0 / (kT)]; r = r 0 exp [E 0 / (kT)]

where g 0 and r 0 are constant values ​​for a given material; E 0 - activation energy of electrical conductivity.

Among the many factors affecting the electrical resistance of ferrites, the main one is the concentration of ferrous iron ions Fe 2+ in them. Under the influence of thermal motion, weakly bound electrons jump from iron ions Fe 2+ to Fe 3+ ions and lower the valence of the latter. With an increase in the concentration of bivalent iron ions, the conductivity of the material increases linearly and, at the same time, the activation energy E 0 decreases. It follows from this that as the ions of variable valence approach each other, the height of the energy barriers, which the electrons must overcome when passing from one ion to the neighboring one, decreases. In spinel ferrites, the activation energy of electrical conductivity usually ranges from 0.1 to 0.5 eV. The highest concentration of ferrous ions and, accordingly, the lowest specific resistance is possessed by magnetite Fe 3 O 4 (iron ferrite), in which r = 5 · 10 -5 Ohm · m. At the same time, the concentration of Fe 2+ ions in ferro-garnets is negligible, therefore their resistivity can reach high values ​​(up to 10 9 Ohm · m).

It has been experimentally established that the presence of a certain amount of bivalent iron ions in spinel ferrites leads to a weakening of anisotropy and magnetostriction; this has a favorable effect on the value of the initial magnetic permeability. Hence follows the following pattern: ferrites with high magnetic permeability, as a rule, have low resistivity.

Ferrites are characterized by a relatively high dielectric constant, which depends on the frequency and composition of the material. With increasing frequency, the dielectric constant of ferrites decreases. Thus, nickel-zinc ferrite with an initial permeability of 200 at a frequency of 1 kHz has e = 400, and at a frequency of 10 MHz, e = 15. The highest value of e is inherent in manganese-zinc ferrites, in which it reaches hundreds or thousands.

Ions of variable valence have a great influence on the polarization properties of ferrites. With an increase in their concentration, an increase in the dielectric constant of the material is observed.

All the diversity of life on our planet has arisen, evolved and now exists due to continuous interaction with various environmental factors, adapting to their influence and changes, using them in life processes. And most of these factors are electromagnetic in nature. Throughout the epoch of evolution of living organisms, electromagnetic radiation exists in their habitat - the biosphere. Such electromagnetic fields are called natural.

Natural radiation is related toThere are weak electromagnetic fields created by living organisms, fields of atmospheric origin, electric and magnetic fields of the Earth, solar radiation, and cosmic radiation. When a person began to actively use electricity, use radio communications, etc. etc., then artificial electromagnetic radiation began to enter the biosphere, in a wide frequency range (approximately from 10-1 to 1012 Hz).

The electromagnetic field must be considered as consisting of two fields: electric and magnetic. It can be assumed that in objects containing electrical circuits, an electric field arises when a voltage is applied to live parts, and a magnetic field arises when a current passes through these parts. It is also permissible to assume that at low frequencies, (including 50 Hz), the electric and magnetic fields are not related, therefore they can be considered separately, as well as the effects they exert on a biological object.

It is customary to evaluate the effect of an electromagnetic field on a biological object by the amount of electromagnetic energy absorbed by this object when it is in the field.

Artificial low-frequency electromagnetic fields are for the most part created by power plants, power lines (PTL), electrical household appliances operating from the network.

Calculations performed for actual conditions have shown that at any point of the low-frequency electromagnetic field arising in electrical installations, at industrial facilities, and. etc., the energy of the magnetic field absorbed by the body of a living organism is about 50 times less than the energy of the electric field absorbed by it. Together with those measurements in real conditions, it was found that the magnetic field strength in the working areas of open switchgears and overhead lines with a voltage of up to 750 kV does not exceed 25 A / m, while the harmful effect of a magnetic field on a biological object is manifested at , many times greater.

Based on this, it can be concluded that the negative effect of the electromagnetic field on biological objects in industrial electrical installations is due to the electric field; the magnetic field, on the other hand, has little biological effect and can be neglected under practical conditions.

A low-frequency electric field can be considered at any given moment as an electrostatic field, that is, the laws of electrostatics can be applied to it. This field is created between at least two electrodes (bodies), which carry charges of different signs and on which lines of force begin and end.

Low-frequency radio waves have a very long wavelength (from 10 to 10,000 km), so it is difficult to install a screen that would not let this radiation through. Radio waves will bend around it unhindered. Therefore, low-frequency radio waves that have a sufficient supply of energy can propagate over sufficiently long distances.

It is assumed that low-frequency electromagnetic radiation is the most extensive type of pollution that has global adverse consequences for living organisms and for humans.

Low-frequency electromagnetic fields (LF EMF) in household

conditions from various external and internal sources, the influence of this factor on the health of the population was studied.

During the operation of electric power installations - open switchgears (OSG) and overhead transmission lines (OHL) of extra-high voltage (330 kV and above), a deterioration in the health of the personnel serving these installations was noted. Subjectively, this was expressed in the deterioration of the state of health of the workers, who complained of increased fatigue, lethargy, and headaches. bad dream. pain in the heart, etc.

In the conditions of populated areas, the main external source of low-frequency electric and magnetic fields in apartments of residential buildings are power lines of various voltages. In buildings located near power lines, from 75 to 80% of the volume of apartment premises are under the influence of high levels of LF EMF and the population living in them is exposed to this adverse factor around the clock.

Special observations and studies carried out in the Soviet Union, in Russia and abroad confirmed the validity of these complaints and established that the factor affecting the health of personnel working with electrical equipment is the electromagnetic field that occurs in the space around the live parts of operating electrical installations.

An intense electromagnetic field of industrial frequency causes a disturbance in the functional state of the central nervous and cardiovascular systems in workers. At the same time, there is increased fatigue, a decrease in the accuracy of working movements, changes in blood pressure and pulse, the occurrence of pain in the heart, accompanied by palpitations and arrhythmias, etc.

It is assumed that the dysregulation of the physiological functions of the body is due to the effect of a low-frequency electromagnetic field on various parts of the nervous system. In this case, an increase in the excitability of the central nervous system occurs due to the reflex action of the field, and the inhibitory effect is the result of the direct action of the field on the structures of the brain and spinal cord. It is believed that the cerebral cortex, as well as the diencephalon, are especially sensitive to the effects of an electric field. It is also assumed that the main material factor causing these changes in the body is the current induced in the body (i.e., the induced magnetic component of the field), and the influence of the electric field itself is much less. It should be noted that in fact both the induced current and the electric field itself have an effect.

The action of electromagnetic fields on cells.

Let us consider the effect of electromagnetic fields (including low-frequency ones) on the cells of living organisms.

The effects caused by the action of electric fields on cell membranes can be classified as follows: 1) a reversible increase in the permeability of cell membranes (electroporation), 2) electrofusion, 3) movement in an electric field (electrophoresis, dielectrophoresis and electrophoresis), 4) membrane deformation, 5 ) electrotransfection, 6) electroactivation of membrane proteins.

The movement of cells in an electric field is of two types. A constant field causes the movement of cells with a surface charge - the phenomenon of electrophoresis. When cell suspensions are exposed to an alternating inhomogeneous field, cell movement occurs, called dielectrophoresis. In dielectrophoresis, the surface charge of cells is not essential. The motion occurs due to the interaction of the induced dipole moment with the external field.

In the theory of dielectrophoresis, a cell is usually considered as a sphere with a dielectric shell. The frequency-dependent component of the induced dipole moment for such a spherical particle is written as:

where, is the cyclic frequency. Parameters A1, A2, B1, B2, C1, C2 are determined by the frequency-independent values ​​of the conductivity and dielectric constant of the outer and inner media, as well as the separating shell.

The frequency dependences of the dielectrophoretic force were calculated from the given ratios. Acting on cells in an inhomogeneous electric field, as well as an effort that determines the rotation of cells in a rotating electric field. According to the theory, the dielectrophoretic force is proportional to the real part of the dimensionless parameter K and the gradient of the square of the field strength:

F = 1/2 Re (K) grad E2

The torque is proportional to the imaginary part of the parameter K and the square of the rotating field strength:

F = Im (K) E2

The difference in the directions of the dielectrophoretic force at low (kilohertz) and high (megahertz) frequencies is due to the different orientation of the induced dipole moment with respect to the external electric field. It is known that the dipole moments of poorly conducting dielectric particles in a conducting medium are oriented opposite to the electric field strength vector, and the dipole moments of well-conducting particles surrounded by a low-conducting medium, on the contrary, are oriented co-directionally with the strength vector.

In the case of exposure to a low-frequency field, the membrane is a good insulator, and the current goes around the cell through a conductive medium. The induced charges are distributed as shown in the figure, and amplify the field strength inside the particle. In this case, the dipole moment is antiparallel to the field strength. For a high-frequency field, the conductivity of the membranes is high, therefore the dipole moment will be co-directional with the vector of the electric field strength.

The deformation of membranes under the influence of electromagnetic fields occurs due to the action on the cell surface of forces called Maxwellian stresses. The magnitude and direction of the force acting on cell membranes in an electric field is determined by the ratio

where T― is the force, E is the field strength, n is the normal vector to the surface, ε is the relative dielectric constant of the dielectric, ε0 is the absolute dielectric constant of the vacuum.

In the case of a low-frequency field acting on the cell, the lines of force go around the cell, i.e., the field is directed along the surface. Hence the cross product E is equal to zero. therefore

This force acts on the cell, forcing it to stretch along the lines of force of the field.

When a high-frequency field acts on a cell, the force acting on the membrane stretches the ends of the cells in the direction of the electrodes.

An example of the electroactivation of membrane enzymes is the activation of Na, K-ATPase in human erythrocytes under the action of an alternating field with an amplitude of 20 V / cm and a frequency of 1 kHz. It is essential that electric fields of such a weak intensity do not have a damaging effect on the functions of cells and their morphology. Weak low-frequency fields (60 V / cm, 10 Hz) also have a stimulating effect on the synthesis of ATP by mitochondrial ATPase. It is assumed that electroactivation is due to the effect of the field on the conformation of proteins. A theoretical analysis of a model of facilitated membrane transport with the participation of a carrier (a model with four states of the transport system) indicates the interaction of the transport system with an alternating field. As a result of this interaction, the field energy can be used by the transport system and converted into the energy of the ATP chemical bond.

Influence of weak LF EMF on biorhythms.

The nature and severity of the biological effects of EMF in a peculiar way depend on the parameters of the latter. In some cases, the effects are maximal at some "optimal" EMF intensities, in others they increase with decreasing intensity, in still others they are oppositely directed at low and high intensities. As for the dependence on the frequencies and modulation-temporal characteristics of the EMF, it takes place for specific reactions (conditioned reflexes, changes in orientation, sensations).

The analysis of these regularities leads to the conclusion that the biological effects of weak low-frequency fields, unexplained by their energetic interaction with the substance of living tissues, can be caused by information interactions of EMF with cybernetic systems of the body that receive information from the environment and, accordingly, regulate the processes of vital activity of organisms.

LF EMF of anthropogenic origin are close in parameters to the natural electric and magnetic fields of the Earth. Therefore, in a biological system under the influence of artificial LF EMF, a violation of the biorhythms characteristic of this system can occur.

For example, in the body of a healthy person, the most characteristic short-period rhythms of the central nervous system (CNS) at rest should be considered the oscillatory activity of the electric and magnetic fields of the brain (2-30 Hz), heart rate (1.0-1.2 Hz), respiratory rate ( 0.3 Hz), the frequency of fluctuations in blood pressure (0.1 Hz) and temperature (0.05 Hz). If a person is exposed to LF EMF for a long time, the amplitude of which is large enough, then a violation of natural rhythms (dysrhythmia) may occur, which will entail physiological disturbances.

All biological objects are influenced by the electric and magnetic fields of the Earth. Therefore, most of the changes occurring in the biosphere, to one degree or another, are associated with changes in this field. Obviously, changes in the geomagnetic field are periodic. If there are any deviations from the established period of changes, then a violation of the physiological parameters of biological systems may occur.

These deviations can occur for two reasons. The first reason is natural (for example, the influence of solar activity on the geofield). Moreover, most of the deviations are also periodic. The second reason is anthropogenic in nature, the consequence of which is the violation of the frequency spectrum of the parameters of the external environment. In the general case, any noticeable deviation of the frequency spectrum of artificial fields from the optimal one determined by the spectrum of the Earth's geomagnetic field should be considered harmful.

We can say that in the process of evolution, living nature used natural EMF of the external environment as sources of information that ensured the continuous adaptation of organisms to changes in various environmental factors: coordination of vital processes with regular changes, protection from spontaneous changes, and this led to the use of EMF as information carriers. providing interconnections at all levels of the hierarchical organization of living nature, from the cell to the biosphere. The formation of information links in living nature by means of EMF, in addition to the known types of information transmission through the senses, nervous and endocrine systems, was due to the reliability and cost-effectiveness of "biological radio communication".

Latest news

• 01.24.18 Cells responsible for registering excess weight are open

  Swedish scientists, scientifically, have established that human cells. Found in bone tissue, they are responsible for registering changes in human body weight, and then report this to the whole body.
  Researchers conducted a series of experiments at the University of Gothenburg on experimental obese mice. The first group of experimental subjects were implanted under the skin of small weights, accounting for 15 percent of their weight, the second group was implanted with hollow capsules, which made up 3 percent of the weight of the rodent.
  The first group of experimental subjects, with real weights, lost weight in two weeks, which was equal to the mass of the introduced load, while their body fat significantly decreased. During the reverse course of the experiment, when the implanted weights were removed, the subjects regained their previous weight.
  Scientists believe that cells that produce bone tissue in the human body are responsible for registering excess load. These cells are called osteocytes. Experiments and observations are ongoing.

• 12/01/17 An experiment is proposed to search for the quantum properties of gravity

  For many decades there have been attempts to combine quantum mechanics with the special theory of relativity. Many theories have been put forward, including the famous string theory, but it is not even clear whether gravity has quantum properties.

  One way to solve the problem involves observing gravitational waves, constructing a detailed theory of them, and eliminating those models of quantum gravity that would contradict it.

  Recently physicists have proposed a radically different approach - an experimental search for deviations from the predictions of classical physics. If gravity is indeed quantized, then space-time itself will not be continuous, which means that in the simplest systems there will be negligible deviations from the classical laws of nature.

  Scientists propose to investigate a variety of optomechanical systems with high sensitivity and look for deviations in them. Unlike huge systems for searching for gravitational waves, the dimensions of which are tens of kilometers, it is proposed to use very compact systems, since quantum gravity is inhomogeneous on extremely small scales.

  It is argued that now our technical capabilities are sufficient and the success of such an experiment is quite possible.

• 10/09/17 The neural network has learned to read images in the human brain

  Scientists have taken many measurements on a functional MRI machine and very accurately measured the activity of various parts of the brain when watching videos. Three subjects watched hundreds of videos of various types under supervision.

  Thanks to this detailed information, the researchers were able to use the neural network and train the program to predict the parameters of brain activity from the video. The inverse problem was also solved - to determine the type of video clip by the active areas of the brain.

  When showing new videos, the neural network could predict the readings of the magnetic resonance imager with an accuracy of 50%. When a network trained on one of the participants was used to predict the type of video viewed by another participant, the prediction accuracy dropped to 25%, which is also relatively high.

  Scientists are getting closer to digitizing mental images, preserving them and transmitting them to other people. They began to better understand the human brain and the peculiarities of processing video information in it. Perhaps someday, thanks to the development of this technology, people will be able to show each other their dreams.

Magnetic fields can be constant from artificial magnetic materials and systems, pulsed, infra-low frequency (with a frequency of up to 50 Hz), variable.

Exposure to electromagnetic fields of industrial frequency is associated with high-voltage power lines, sources of constant magnetic fields used in industrial enterprises.

Sources of permanent magnetic fields are permanent magnets, electromagnets, electrolysis baths (electrolyzers), direct current transmission lines, busbars and other electrical devices that use direct current. A constant magnetic field is an important factor in the production environment in the manufacture, quality control, and assembly of magnetic systems.

Magneto-pulse and electro-hydraulic installations are sources of low-frequency pulsed magnetic fields.

The constant and low-frequency magnetic field rapidly decreases with distance from the source.

The magnetic field is characterized by two values ​​- induction and intensity. Induction B is the force acting in a given field on a unit-length conductor with unit current, measured in teslas (T). Intensity H is a value that characterizes the magnetic field regardless of the properties of the medium. The tension vector coincides with the induction vector. The unit of measurement of tension is ampere per meter (A / m).

Electromagnetic fields (EMF) of industrial frequency include power lines with voltages up to 1150 kV, open switchgears, switching devices, protection and automation devices, and measuring instruments.

Overhead power lines (50 Hz). Exposure to EMF of industrial frequency is associated with high-voltage power lines (VL), sources of constant magnetic fields used in industrial enterprises.

The intensity of EMF from overhead power lines (50 Hz) largely depends on the line voltage (110, 220, 330 kV and above). Average values ​​at the workplaces of electricians: E = 5 ... 15 kV / m, Η = 1 ... 5 A / m; on bypass routes for service personnel: E = 5..30 kV / m, H = 2 ... 10 A / m. In residential buildings located near high-voltage lines, the electric field strength, as a rule, does not exceed 200 ... 300 V / m, and the magnetic field does not exceed 0.2 ... 2 A / m (V = 0.25 ... 2 , 5 mT).

The magnetic field near power lines (PTL) with a voltage of 765 kV is 5 μT directly under the transmission line and 1 μT - at a distance of 50 m from the transmission line. The picture of the distribution of the electromagnetic field depending on the distance to the power transmission line is shown in Fig. 5.6.

EMF of industrial frequency is mainly absorbed by the soil, therefore, at a short distance (50 ... 100 m) from power lines, the electric field strength drops from tens of thousands of volts per meter to standard values. Significant danger is posed by magnetic fields arising in areas near power transmission lines (PTL) of industrial frequency currents, and in areas adjacent to electrified railways. High-intensity magnetic fields are also found in buildings located in the immediate vicinity of these areas.

Rice. 5.6. Electric and magnetic field under power lines with a voltage of 765 kV (60 Hz) at a current of 426 A, depending on the distance to the power line (line height 15 m)

Rail electric transport. The strongest magnetic fields over large areas in densely populated urban environments and in workplaces are generated by public electric rail vehicles. The theoretically calculated picture of the magnetic field generated by typical currents from the railway is shown in Fig. 5.7. Experimental measurements carried out at a distance of 100 m from the rail track gave a magnetic field of 1 μT.

The level of transport magnetic fields can exceed the corresponding level from power lines by 10 ... 100 times; it is comparable and often exceeds the Earth's magnetic field (35 ... 65 μT).

Electric networks of residential buildings and household low-frequency devices. In everyday life, sources of EMF and radiation are televisions, displays, microwave ovens and other devices. In conditions of low humidity (less than 70%), electrostatic fields create clothing and household items (fabrics, rugs, capes, curtains, etc.). Commercial microwave ovens are not hazardous, but the failure of their protective shields can significantly increase the leakage of electromagnetic radiation. TV screens and displays as sources of electromagnetic radiation in everyday life do not pose a great danger even with prolonged exposure to a person, if the distance from the screen exceeds 30 cm.

Rice. 5.7. Configuration of the magnetic field from the electrified railroad

Quite strong magnetic fields can be found at 50 Hz near household appliances. So, a refrigerator creates a field of 1 μT, a coffee maker - 10 μT, a microwave oven - 100 μT. Such magnetic fields of much greater length (from 3 ... 5 to 10 μT) can be observed in the working areas of steel production when using electric furnaces.

The intensity of electric fields near long wires connected to the 220 V network is 0.7 ... 2 kV / m, near household appliances with metal cases (vacuum cleaners, refrigerators) - 1 ... 4 kV / m.

Table 5.6 shows the values ​​of magnetic induction around some household appliances.

In the overwhelming majority of cases, a network with one zero (zero working) conductor is used in residential buildings, networks with zero working and protective conductors are quite rare. In such a situation, the risk of electric shock increases when the phase wire is shorted to the metal case or chassis of the device; metal casings, chassis and instrument cases are not grounded and are a source of electric fields (when the instrument is turned off with a plug in the socket) or electric and magnetic fields of industrial frequency (when the instrument is turned on).

Table 5.6. Values ​​of magnetic induction B near household appliances, μT

	Distances from devices, cm
			Less than 0.01 ... 0.3
Shavers			Less than 0.01 ... 0.3
Vacuum cleaners
Wiring
Portable heaters
TV sets			Less than 0.01 ... 0.15
Washing machines			Less than 0.01 ... 0.15
Electric irons
Fans
Refrigerators