Natural Geomagnetic Field Research Articles

Investigations of a simulated geomagnetic field experienced by the international space station on attentional performance

We have previously reported that the exposure to an abnormal magnetic field simulating the one encountered by the International Space Station (ISS) orbiting around the Earth may enhance autonomic response to emotional stimuli. Here we report the results of the second part of that study which tested whether this field also affects cognitive functions. Twenty-four volunteers participated in the study, 12 exposed to the natural geomagnetic field and 12 to the magnetic field encountered by ISS. The test protocol consisted of a set of eight tests chosen from a computerized test battery for the assessment of attentional performance. The duration of exposure was 90 min. No effect of exposure to ISS magnetic field was observed on attentional performance.

Prolonged weakening of the geomagnetic field (GMF) affects the immune system of rats

The aim of this study was to find out how a long-term shielding of the geomagnetic field (GMF) affected the immune system of rats. Male and female Wistar rats were kept up to an age of 2 months in a natural GMF (about 37 microT). Afterwards, the rats were divided into four groups (males and females separately): control rats were maintained in ambient GMF, while experimental animals were housed under conditions of a weakened GMF (below 12 microT) achieved with steel cages. After 6 months, the rats were sacrificed by decapitation. Spleens and thymuses were isolated and weighed. Peritoneal cells were eluted and cultured in vitro to study their ability to produce nitric oxide (NO) and to synthesize superoxide anion (O2(-)), important microbicidal molecules of macrophages. The number of macrophages was estimated by a crystal violet staining method. We found that the long-term shielding of the GMF could influence the functioning of the immune system in a sex-dependent manner. The deprivation of the GMF delayed physiological thymus involution, that effect being more strongly expressed in females. The weakening of the GMF resulted in an increased number of peritoneal macrophages, especially in males. The shielding of the GMF diminished the ability of macrophages to release NO and to synthesize O2(-), those effects being more powerfully expressed in males and females, respectively. It is proposed that the observed changes in the immune system occur as a consequence of the protective effect of GMF shielding on the circadian rhythm-dependent level of melatonin.

Do naturally occurring magnetic nanoparticles in the human body mediate increased risk of childhood leukaemia with EMF exposure?

Purpose: To develop the hypothesis that magnetic nanoparticles, found in many organisms and often involved in biological reactions to weak electromagnetic fields (EMF), mediate EMF-induced DNA damage which could result in increased risk of childhood leukaemia and other cancers.Materials and methods: An analysis of current research into magnetic nanoparticles. Physics estimates and the development of the hypothesis that intracellular magnetic nanoparticles chronically change the free radical concentration and can mediate the enhanced rate of DNA damage in hematopoietic stem cells.Results: The properties of magnetic nanoparticles are considered and the naturally occurring magnetic field generated by a magnetic nanoparticle within a cell is calculated to be in the range of about 1–200 millitesla, which exceeds the level of the natural geomagnetic field by orders of magnitude. Experiments are summarized on the biological effects of static magnetic field in this range. It is shown that magnetic nanoparticles can increase the rate of free radical formation by a few percent, in the course of an idealized radical-pair reaction in a cell. A mechanism is discussed that explains how weak alternating magnetic fields, of the order of 0.4 μT, could cause an increase in the rate of leukaemia via millitesla fields produced around superparamagnetic nanoparticles in hematopoietic stem cells.Conclusions: The postulated presence of magnetic nanoparticles located in hematopoietic stem cells could constitute a cancer risk factor. Superparamagnetic nanoparticles can possibly mediate increased level of leukaemia caused by background exposure to low-frequency weak EMF.

Tidal components of geomagnetic variations

The natural geomagnetic field is constantly disturbed. The total registered effect of geomagnetic variations depends on both planetary and local processes. Planetary sources and sources in the Earth’s core respond to tidal effects. In the accepted model, the complex MHD processes in the Earth’s outer core are approximated by the assumed ring current in the equatorial plain of the liquid core. The geomagnetic variation originating as a result of tidal deformations of ring currents are ∼10−4 and 0.10–1 nT in the liquid core and magnetosphere, respectively. The calculated values coincide in order of magnitude with the processed geomagnetic measurements at Paratunka observatory (Kamchatka region).

The effects of a weak permanent magnetic field on the lipid composition and content in the onion leaves of various ages

We have studied the effects of a weak permanent magnetic field (PMF) with strength of 403 A/m on the composition and content of polar and neutral lipids and the composition of their fatty acids (FAs). The lipids were isolated from the third, fourth, and fifth leaves of onion (Allium cepa L., cv. Arzamasskii) plants, and their composition was determined using TLC and GLC techniques. Plants growth under the conditions of a natural geomagnetic field served as a control. Most intense changes in the lipid content induced by PMF were observed in the fourth onion leaf. The content of total lipids and that of polar lipids (glyco-and phospholipids) changed, whereas the content of neutral lipids either decreased or remained unchanged. The phospholipid/sterol ratio increased, causing an increase in the fluidity of the membrane lipid bilayer. PMF induced an increase in the concentration of linolenic acid and the relative content of total unsaturated FAs. The effects of PMF on the content and composition of lipids in the third and fifth onion leaves were less pronounced, demonstrating differences between the leaves of various ages in their sensitivity to the effects of magnetic field. It is concluded that changes in the weak PMF within the limits of changes in the strength of geomagnetic field in the course of evolution can affect biochemical and physiological processes of plants.

An experimental analysis on the magnetic field sensitivity of the black-meadow antFormica pratensisRetzius (Hymenoptera: Formicidae)

Ant responses were tested under both the natural geomagnetic and artificially induced Earth-strength electromagnetic field. Foragers were trained for a month to visit a food source at the north arm accessed through an orientation platform assembly. Under the natural geomagnetic field, when all other orientational cues were eliminated, results indicated significant heterogeneity of ant distribution with the majority seeking geomagnetic north in darkness. However, in light, foragers failed to discriminate geomagnetic north. Under shifted artificial electromagnetic field, orientation was predominantly on the artificial magnetic N/S axis with a significant preference for the artificial north in both light and dark conditions.

Magnetization of Steel Building Materials and Structures in the Natural Geomagnetic Field

This paper presents the physical basis of the magnetic properties of ferromagnetic materials and shows their relationships with external geomagnetic field. It graphically processes the experimental data detected by an HMR magnetometer. Taking into account the natural geomagnetic field under the effects of steel U profiles, variations of the natural geomagnetic field in a steel structure building are indicated and the potential existence of Sick Building Syndrome (SBS) in these types of buildings is pointed out.

Migratory Birds Use Head Scans to Detect the Direction of the Earth's Magnetic Field

Night-migratory songbirds are known to use a magnetic compass , but how do they detect the reference direction provided by the geomagnetic field, and where is the sensory organ located? The most prominent characteristic of geomagnetic sensory input, whether based on visual patterns or magnetite-mediated forces , is the predicted symmetry around the north-south or east-west magnetic axis. Here, we show that caged migratory garden warblers perform head-scanning behavior well suited to detect this magnetic symmetry plane. In the natural geomagnetic field, birds move toward their migratory direction after head scanning. In a zero-magnetic field , where no symmetry plane exists, the birds almost triple their head-scanning frequency, and the movement direction after a head scan becomes random. Thus, the magnetic sensory organ is located in the bird's head, and head scans are used to locate the reference direction provided by the geomagnetic field.

Static magnetic fields: animal studies

Various experimental studies carried out over the last 30–40 years have examined the effects of the chronic or acute exposure of laboratory animals to static magnetic fields. Many of the earlier studies have been adequately reviewed elsewhere; few adverse effects were identified. This review focuses on studies carried out more recently, mostly those using vertebrates, particularly mammals. Four main areas of investigation have been covered, viz., nervous system and behavioural studies, cardiovascular system responses, reproduction and development, and genotoxicity and cancer. Work on the role of the natural geomagnetic field in animal orientation and migration has been omitted. Generally, the acute responses found during exposure to static fields above about 4 T are consistent with those found in volunteer studies, namely the induction of flow potentials around the heart and the development of aversive/avoidance behaviour resulting from body movement in such fields. No consistently demonstrable effects of exposure to fields of ∼1 T and above have been seen on other behavioural or cardiovascular endpoints. In addition, no adverse effects of such fields on reproduction and development or on the growth and development of tumours have been firmly established. Overall, however, far too few animal studies have been carried out to reach any firm conclusions.

Exposure to hypomagnetic field space for multiple generations causes amnesia in Drosophila melanogaster

This is the introduction of Drosophila into the study of learning and memory affected by removal of the geomagnetic field (GMF) for successive generations. Using the operant visual learning/memory paradigm at a flight simulator, the present study revealed that wild-type flies raised in a hypomagnetic field environment continuously for 10 successive generations were gradually impaired in visual conditioning learning and memory formation and finally the 10th generation flies became morphs of nonlearners and completely amnesiac. The control experiments show that the impairment could not be ascribed to any apparent sensorimotor problems in Drosophila. The reverse shift from hypomagnetic field (HMF) to natural GMF restored the GMF-free induced amnesia fully after six consecutive generations. Thus, our findings demonstrate conclusively that some serious, but reversible learning and memory impairment may occur for living organisms in a prolonged separation from GMF over many consecutive generations. And Drosophila has the potential to develop into a new model organism for the study of the neurobiology of magnetism for multiple generations.

Long-term memory was impaired in one-trial passive avoidance task of day-old chicks hatching from hypomagnetic field space

The retained curve in one-trial passive avoidance task (OTPAT) of day-old chicks hatching from natural geomagnetic field (control groups) is consistent with the acknowledged three-phase model. The two dips are at the 20th min and the 60 min, and the avoidance rates (AR) to the red bead in short-and intermediate-term memory are 68.4% on average, while that in the long-term momory was 74.8%. The OTPAT retained curve of day-old chicks hatching from hypomagnetic field space (experimental groups) presents the marked timing effect. The two dips were at the 25th min and the 50th min, the avoidance rates to the red bead (ARR) in the short-and intermediate-term memory was 74.1% on an average, which was resembled to that in control group; however, the long-term memory appeared an obvious fluctuation. Compared with that in control groups, ARR and the deviation coefficient in experimental groups were decreased by 25.3% and increased by 1.3 times, respectively. That is to say, both the memory ability and stability in the experimental chicks declined. The result shows that the hypomagnetic field space has a negative effect on the development of chick brain function, and that cannot be negligible.

Verapamil protective effect on natural and artificial magnetic field cardiovascular impact

Previously we found an opposite effect of artificial static magnetic field (SMF) and natural geomagnetic field (GMF) on arterial baroreceptors. A 0.35 T SMF increased baroreflex sensitivity (BRS), whereas GMF disturbance decreased BRS. Here, we investigated interrelated impacts on arterial baroreceptors of 0.35 T SMF, generated by Nd(2)-Fe(14)-B alloy magnets, GMF, and verapamil, a Ca(2+) channel blocking agent. We measured BRS in rabbits before and after local SMF exposure of sinocarotid baroreceptors or after simultaneous SMF and verapamil application, in conjunction with geomagnetic disturbance during actual experimental run (determined by K-index) and geomagnetic disturbance over the preceding 24 h of each experiment (A(k)-index). BRS was estimated from peak responses of mean arterial pressure (MAP) and heart rate, expressed as percentages of the resting values preceding each pair of pressure (phenylephrine) and depressor drug (nitroprusside) injections. Prior to verapamil and/or SMF application we found a significant positive correlation of K-index with MAP (t = 2.39, P =.021, n = 44), but negative with BRS (t = -4.60, P =.0003, n = 44), and found a negative correlation of A(k)-index with BRS (t = -2.7, P = 0.01, n = 44). SMF induced an increase in BRS (0.79 +/- 0.1 vs. 1.15 +/- 0.1 bpm%/mmHg%, initial value vs. SMF exposure, P <.0002, n = 26). Verapamil infusion blocked the SMF and GMF effect on BRS, indicating Ca(2+) channels as a possible site of both fields' impact. SMF and GMF probably affect baroreceptor sensory transduction, modulating baroreceptor membranes' Ca(2+) channel permeability.

Nuclear magnetic resonance as a geophysical tool for hydrogeologists

The proton Magnetic Resonance Sounding (MRS) is a geophysical technique specially designed for hydrogeological applications. It is based on the principle of Nuclear Magnetic Resonance (NMR) and allows the non-invasive detection of free water in the subsurface. As with many other geophysical methods, MRS is site-dependent. Modeling results show that MRS performance depends on the magnitude of the natural geomagnetic field, the electrical conductivity of rocks, the electromagnetic noise and other factors. For example, the maximum depth of groundwater detection for currently available equipment can vary from 45 to 170 m depending on measurement conditions, although an average depth of investigation is generally considered to be about 100 m. The processing of MRS data can provide the depth, thickness and water content of aquifers. Based on the water content and the relaxation times T 1 and T 2* provided by MRS, in association with calibration using borehole pumping test data, it is possible to estimate the aquifer's hydrodynamic properties, namely permeability, transmissivity, and specific yield. In this aim, experience gained through NMR logging has been applied to MRS data interpretation and a comparison between the results of borehole pumping tests and those of MRS experiments reveals a good correlation. An example of an MRS survey in Saudi Arabia is presented. The study area is some 1.3 km 2 and underlain by an aquifer composed of fractured diorite. The results of 7 borehole pumping tests and 13 MRS measurements show good agreement.

誘導磁力計による車載スピードメーターの開発

A new speedometer of vehicle using induction magnetometer has been designed and evaluated, while the wheels of vehicle were magnetized through natural geomagnetic field and by some artificial magnetic field as well. As a magnetized wheel rotated during a movement of a vehicle, periodic magnetic patterns are propagated and then detected by an induction magnetometer or a sensor which is placed nearby the wheel. The high-frequency components, which may cause aliasing, are eliminated using an anti-aliasing filter (Low Pass Filter; cutoff=40Hz). The desired Low-frequency components of the induced electric signals are proceeded and converted into digital data by ADC (Analog to Digital Converter; 10bit) that includes RISC (Reduced Instruction Set Computer). Primary parameters, such as a diameter(r) of a vehicle’s tire and estimated time period T of a rotated tire, should be set to determine the speed of the vehicle from the following equation V=2πr/T. The characteristics of the new speedometer have been evaluated with a conventional speedometer. We expect that our proposed sensor is very proper for speed control or measurement of automatic vehicles for ITS(Intelligent Transport System).

Evidence for the use of magnetic cues in mound construction by the termite Amitermes meridionalis (Isoptera : Termitinae)

The termite Amitermes meridionalis builds meridionally elongated mounds. We removed the tops of such mounds and then allowed the termites to repair their mounds in the natural geomagnetic field and in artificial magnetic fields with different magnetic declinations. Cross-sections of repaired mounds were taken and the arrangement of the small, elongated cells that form the basis of mound architecture was assessed. The results suggest that the termites align mound cells along the existing axis of the mound and the cardinal axes of the horizontal component of the applied magnetic field.

Growth of Green Onions in a Weak Permanent Magnetic Field

Effect of a weak permanent magnetic field (PMF) with a strength of 403 A/m on Allium cepaL. bulb sprouting and leaf growth was investigated. Two onion varieties to produce green onions (cv. Arzamasskii) and bulb onions (cv. Ryazanskii) were examined. In addition, the content of chlorophyll, carbohydrates, and protein in the leaves of the control and PMF-treated plants were determined. The plants of the control group were grown under a natural geomagnetic field. The treatment of onions with PMF accelerated sprouting and extended the length of the fourth leaf in cv. Arzamasskii as much as 40%; the first leaf in cv. Ryazanskii was lengthened by 25% with respect to its length in untreated plants. Exposure to PMF increased the number of sprouts in cv. Ryazanskii and the number of sprout bunches in cv. Arzamasskii. In addition, PMF elevated the total content of chlorophyll and protein, expressed per fresh weight of green onions, but had no effect on the total content of carbohydrates. Conversely, PMF reliably reduced the total content of chlorophyll and protein in cv. Ryazanskii. The temperature increase diminished the effects of PMF.

MEDIUM CULTURE COMPOSITION AND ORGANOGENESIS PROCESSES IN DROSERA ROTUNDIFOLIA

Drosera rotundifolia explants were inoculated on culture media supplemented with either single ferrofluids with different Fe 2+ / Fe 3+ , ratios or complex ferrofluids. Development took place at different natural or double geomagnetic field values. The effect of culture medium supplementation and geomagnetic field values on organogenesis and plant growth rhythm is discussed.

Effect of Wavelength of Light and Pulse Magnetisation on Different Magnetoreception Systems in a Migratory Bird

Two hypotheses on magnetoreception in animals are currently discussed. The first hypothesis is based on light-dependent processes associated with the visual system, while the second hypothesis suggests that magnetoreception is based on biogenic magnetite. Both mechanisms are supported by experimental evidence, but whether the information they provide involves the magnetic compass or the ‘map’ is still open. In order to identify the relevance of light-dependent or magnetite-transduced processes in magnetoreception, juvenile migratory birds were tested for their orientation behaviour in the natural geomagnetic field as the only directional cue available to them. The test birds were juvenile Tasmanian silvereyes (Zosterops l. lateralis), which were caught on their native island soon after fledging, before they had an opportunity to establish a navigational ‘map’. (1) Under ‘white’ (full spectrum) and green light (571 nm), they were well oriented in their appropriate migratory direction, while they were disoriented under red light (633 nm). This coincides with previous findings on adult silvereyes and suggests that light-dependent processes are involved in an orientation mechanism used by both juvenile and adult migrants, namely the magnetic compass. (2) A short, high-intensity magnetic pulse, a treatment designed to alter the magnetisation of magnetite, did not affect the young birds´ orientation. They continued to select their seasonally appropriate migratory direction. In contrast, adult silvereyes from the same population had responded in a previous study with a 90° clockwise deflection from their normal migratory course. These results suggest that (a) magnetite is involved in an orientation mechanism used exclusively by adult migrants; and (b) a magnetite-based receptor is associated with the navigational ‘map’, which provides information on geographic position.

The role of skylight polarization in the orientation of a day-migrating bird species

To assess the role of skylight polarization in the orientation system of a day-migrating bird, Yellow-faced Honeyeaters (Lichenostomus chrysops, Meliphagidae) were tested in funnel cages for their directional preferences. In control tests in the natural local geomagnetic field under the clear natural sky, they preferred their normal migratory course. Manipulations of the e-vector by depolarizing the skylight or rotating the axis of polarization failed to affect the orientation as long as the natural geomagnetic field was present. When deprived of magnetic information, the birds continued in their normal migratory direction as long as they had access to information from the natural sky, or when either the sun or polarized light was available. However, when sun was hidden by clouds, depolarizers caused disorientation. — These findings indicate that polarized skylight can be used for orientation when no other known cues are available. However in the hierarchy of cues of this species, the polarization pattern clearly ranks lower than information from the geomagnetic field.

Geomagnetic Field and Artificial 0.2 T Static Magnetic Field Combined Effect on Blood Pressure

We investigated the influence of the external time-varying component of the natural geomagnetic field–geomagnetic activity–on the degree of the 0.2 T static magnetic field (SMF) hypotensive effect. We showed previously that 0.2 T SMF applied to the carotid sinus area of anesthetized rabbits had a hypotensive effect under norepinephrine-induced hypertensive conditions (1).We found that the degree of the 0.2 T SMF hypotensive effect depends on the level of the geomagnetic activity at the time of the experiment and is maximal for days with disturbed geomagnetic activity.We concluded that in the evaluation of artificial electromagnetic fields biological effects, geomagnetic field activity must be taken into consideration, because of a possible modulating effect.