Weak Electric Currents Research Articles

Electric signal emissions during repeated abrupt uniaxial compressional stress steps in amphibolite from KTB drilling

Abstract. Laboratory experiments have confirmed that the application of uniaxial stress on rock samples is accompanied by the production of weak electric currents, to which the term Pressure Stimulated Currents – PSC has been attributed. In this work the PSC emissions in amphibolite samples from KTB drilling are presented and commented upon. After having applied sequential loading and unloading cycles on the amphibolite samples, it was ascertained that in every new loading cycle after unloading, the emitted PSC exhibits lower peaks. This attitude of the current peaks is consistent with the acoustic emissions phenomena, and in this work is verified for PSC emissions during loading – unloading procedures. Consequently, the evaluation of such signals can help to correlate the state and the remaining strength of the sample with respect to the history of its mechanical stress.

Measurement of weak electric currents in copper wire phantoms using MRI: influence of susceptibility enhancement

The use of magnetic resonance imaging (MRI)-based methods for the direct detection of neuronal currents is a topic of intense investigation. Much experimental work has been carried out with the express aim of establishing detection thresholds and sensitivity to flowing currents. However, in most of these experiments, magnetic susceptibility enhancement was ignored. In this work, we present results that show the influence of a susceptibility artefact on the detection threshold and sensitivity. For this purpose, a novel phantom, consisting of a water-filled cylinder with two wires of different materials connected in series, was constructed. Magnitude MR images were acquired from a single slice using a gradient-echo echo planar imaging (EPI) sequence. The data show that the time course of the detected MR signal magnitude correlates very well with the waveform of the input current. The effect of the susceptibility artefacts arising from the two different wires was examined by comparing the magnitudes of the MR signals at different voxel locations. Our results indicate the following: (1) MR signal enhancement arising from the magnetic susceptibility effect influences the detection sensitivity of weak current; (2) the detection threshold and sensitivity are phantom-wire dependent; (3) sub-mu A electric current detection in a phantom is possible on a 1.5-T MR scanner in the presence of susceptibility enhancement.

Resolution and Contrast in Magnetic Resonance Electrical Impedance Tomography (MREIT) and its Application to Cancer Imaging

It has been reported that the electrical impedance of malignancies could be 20-40 times lower than healthy tissues and benign formations. Therefore, in vivo impedance imaging of suspicious lesions may prove to be helpful in improving the sensitivity and specificity of detecting malignant tumors. Several systems have been developed to map the conductivity distribution inside a volume of tissue, however they suffer from poor spatial resolution because the measurements are taken only from surface electrodes. MRI based impedance imaging (MREIT) is a novel method, in which weak electrical currents are injected into the tissue and the resulting perturbations in the magnetic field are measured using MRI. This method has been shown to provide better resolution compared to previous techniques of impedance imaging because the measurements are taken from inside the object on a uniform grid. Thus, it has the potential to be a useful modality that may detect malignancies earlier. Several phantom imaging experiments were performed to investigate the spatial resolution and dynamic range of contrast of this technique. The method was also applied to a live rat bearing a R3230 AC tumor. Tumor location was identified by contrast enhanced imaging.

Piezo stimulated currents in marble samples: precursory and concurrent-with-failure signals

Abstract. The Earth’s electric field transient variations are promising candidates of earthquake precursors. In order to study the physical mechanisms of such precursory signals, laboratory experiments of uniaxial compression were carried out. More specifically the behaviour of stressed marble samples from Penteli Mountain was investigated. The samples were subjected to a time-varying uniaxial compression at both variable and constant stress rates. During the first set of experiments weak electric currents were detected during pressure variations. Such Piezo Stimulated Currents (PSC) were detected while stress steps, both positive and negative were applied, the maximum stress never being greater than the elasticity limit. During the second set of experiments stress was applied at a constant rate starting from zero-stress and ending in fracture. In the region beyond the elastic limit a PSC was detected which after reaching a peak suffered a reversal in its polarity just before fracture. In a third set of experiments the same procedure was applied to previously structurally damaged samples taking care not to fracture them. In all cases the PSC followed the variation of stress and moreover it was observed that a linear relationship existed between the PSC maxima and the corresponding stress-rate maxima. The mechanism responsible for the described phenomena can be ascribed to the Moving Charged Dislocations model.

Electronic three-dimensional imaging of intestinal endoscopy

Endoscopists, especially those investigating the colon, need to know where the tip of the instrument is and whether the tube is kinking. A three-dimensional real-time imaging system consisting of sensors, within or taped to the endoscope, to detect weak electric currents in a wire grid below the mattress yields the information needed and should greatly facilitate performance and teaching of endoscopy.

Synergism between electrolysis and methylene blue photodynamic action in Escherichia coli.

There is interest in the use of photodynamic therapy for the treatment of certain diseases, including cancer. However, weak penetration of visible light in tissues has restricted its use. In this study the possibility of enhancing photodynamic effects by the use of energies that penetrate more deeply in tissues was investigated. Weak electric currents (1.0 mA) applied to Escherichia coli cells for short periods, producing little or no lethal damage, was found to act synergistically with the photodynamic action of methylene blue, significantly enhancing the effects of this treatment. This synergism exists also between electrolysis and X-rays but not between electrolysis and UV-254 nm. It is suggested that this synergism might eventually be used to improve the results obtained in therapeutic practice based on the utilization of photodynamic action.

Synergism between electricity and ionizing radiation

Weak direct electric currents which produce little (or no) lethal damage to Escherichia coli bacteria are shown to act synergistically with ionizing radiation, both electromagnetic radiation (X-ray) and charged particles (β radiation). This synergism greatly enhances the lethal effect of ionizing radiation on bacteria. This is possibly due to increased single-strand breaks in DNA, as detected by the alkaline sucrose gradient method. It is also shown that in cells with thymidine- 3H incorporated into their DNA and treated with electricity, the radioactivity is released from the acid-insoluble fraction to the acid-soluble fraction, so that the ratio of radioactivity in the soluble fraction to that in the insoluble fraction increases from 0.47 in the non-treated control cells to 3.46 in the cells treated with an electric current of 1.0 mA (3.0 V) for 30 min, which indicates extensive degradation of cellular DNA. No synergism is detected between electricity and 254 nm UV radiation nor between electricity and X-rays, when these two agents are used sequentially in any order. Electricity alone produces lesions in cell membranes, as shown by electron microscopy.

The Development and Application of Pulsed Electromagnetic Fields (PEMFs) for Ununited Fractures and Arthrodeses

This article deals with the rational and practical use of surgically noninvasive pulsed electromagnetic fields (PEMFs) in treating ununited fractures, failed arthrodeses, and congenital pseudarthroses (infantile nonunions). The method is highly effective (more than 90 per cent success) in adult patients when used in conjunction with good management techniques that are founded on biomechanical principles. When union fails to occur with PEMFs alone after approximately four months, their proper use in conjunction with fresh bone grafts insures a maximum failure rate of 1 to 1.5 per cent. Union occurs because the weak electric currents induced in tissues by the time-varying fields effect calcification of the fibrocartilage in the fracture gap, thereby setting the stage for the final phases of fracture healing by endochondral ossification. The efficacy, safety, and simplicity of the method has prompted its use by the majority of orthopedic surgeons in this country. In patients with delayed union three to four months postfracture, PEMFs appear to be more successful and healing, generally, is more rapid than in patients managed by other conservative methods. For more challenging problems such as actively infected nonunions, multiple surgical failures, long-standing (for example, more than two years postfracture) atrophic lesions, failed knee arthrodeses after removal of infected prostheses, and congenital pseudarthroses, success can be expected in a large majority of patients in whom PEMFs are used. Finally, as laboratory studies have expanded knowledge of the mechanisms of PEMF action, it is clear that different pulses affect different biologic processes in different ways. Selection of the proper pulse for a given pathologic entity has begun to be governed by rational processes similar, in certain respects, to those applied to pharmacologic agents.

Electrical Control of Growth in Plant Tissue Cultures

When very weak electric currents of the order of 1 microamp were passed between the tissue and the culture medium, dramatic increases in growth were recorded for tobacco callus. The effect was dependent on the direction of the current. When the callus was made negative, the growth rate was stimulated by about 70 percent, whereas current in the reverse direction was slightly inhibitory. The effect might have commercial application in enhancing the yield of biomass for the production of secondary products by immobilised plant tissue cultures.

Electrical Stimulation Ih Orthopaedics: Past, Present Amd Future

The observations that stressed bone yielded an electrical signal and that weak electrical currents could induce callus formation gave birth to a sustained and widening interest in the clinical use of electrical currents and magnetic fields. the question of the physiological significance of the stress-generated signals remains unanswered, but it seems likely that the current-caused callus formation la an Irritative response similar to that demonstrated by bone subjected to heat, chemical, or mechanical stimuli. A similar mechanism may underly the magnetic-field effects on bone. the future of electrical stimulation in orthopaedics seems tenuous, and only further progress will insure its role in clinical use.

The Development and Application of Pulsed Electromagnetic Fields (PEMFs) for Ununited Fractures and Arthrodeses

This article deals with the rational and practical use of surgically noninvasive pulsed electromagnetic fields (PEMFs) in treating ununited fractures, failed arthrodeses, and congenital pseudarthroses (infantile nonunions). The method is highly effective (more than 90 per cent success) in adult patients when used in conjunction with good management techniques that are founded on biomechanical principles. When union fails to occur with PEMFs alone after approximately four months, their proper use in conjunction with fresh bone grafts insures a maximum failure rate of 1 to 1.5 per cent. Union occurs because the weak electric currents induced in tissues by the time-varying fields effect calcification of the fibrocartilage in the fracture gap, thereby setting the stage for the final phases of fracture healing by endochondral ossification. The efficacy, safety, and simplicity of the method has prompted its use by the majority of orthopedic surgeons in this country. In patients with delayed union three to four months postfracture, PEMFs appear to be more successful and healing, generally, is more rapid than in patients managed by other conservative methods. For more challenging problems such as actively infected nonunions, multiple surgical failures, long-standing (for example, more than two years postfracture) atrophic lesions, failed knee arthrodeses after removal of infected prostheses, and congenital pseudarthroses, success can be expected in a large majority of patients in whom PEMFs are used. Finally, as laboratory studies have expanded knowledge of the mechanisms of PEMF action, it is clear that different pulses affect different biologic processes in different ways. Selection of the proper pulse for a given pathologic entity has begun to be governed by rational processes similar, in certain respects, to those applied to pharmacologic agents.

Pulsing electromagnetic field treatment in ununited fractures and failed arthrodeses

Pulsing electromagnetic fields (PEMFs) induce weak electric currents in bone by external coils on casts or skin. This surgically noninvasive, outpatient method, approved by the Food and Drug Administration in November 1979, produced confirmed end results in 1,007 ununited fractures and 71 failed arthrodeses, worldwide. Overall success at Columbia-Presbyterian Medical Center was 81%; internationally, 79%; and in other patients in the United States, 76%. Treatment with PEMFs was effective in 75% of 332 patients (a subset) with an average 4.7-year disability duration, an average of 3.4 previous operative failures to produce union, and a 35% rate of infection. Eighty-four percent of carpal naviculars and 82% of femoral neck-trochanteric nonunions were united. After attempted arthrodeses could not salvage a failed total-knee prosthesis, PEMFs promoted healing in 85% of patients. When coils were unsuccessful alone, combining them with surgical repair was effective.

Pulsing Electromagnetic Field Treatment in Ununited Fractures and Failed Arthrodeses

Pulsing electromagnetic fields (PEMFs) induce weak electric currents in bone by external coils on casts or skin. This surgically noninvasive, outpatient method, approved by the Food and Drug Administration in November 1979, produced confirmed end results in 1,007 ununited fractures and 71 failed arthrodeses, worldwide. Overall success at Columbia-Presbyterian Medical Center was 81%; internationally, 79%; and in other patients in the United States, 76%. Treatment with PEMFs was effective in 75% of 332 patients (a subset) with an average 4.7-year disability duration, an average of 3.4 previous operative failures to produce union, and a 35% rate of infection. Eighty-four percent of carpal naviculars and 82% of femoral neck-trochanteric nonunions were united. After attempted arthrodeses could not salvage a failed total-knee prosthesis, PEMFs promoted healing in 85% of patients. When coils were unsuccessful alone, combining them with surgical repair was effective.

Low-level electrical currents and brain indicators of behavioral activation.

Distinguishing between slow brain potential correlates of arousal and activation on the basis of their functional role and temporal involvement during a reaction-time task, data are presented which suggest that weak electrical polarizing currents applied to the head in human subjects modify predominantly activation indicators rather than arousal ones.

Special Cutaneous Receptor Organs of Fish: Synaptic Structures of Eigenmannia

Special cutaneous receptor organs of fresh-water weakly electric fish are grossly similar to other receptor organs of the acoustico-lateralis system, but differ in numerous cytological details. They are presumed to function as detectors of weak electric currents. Those of Eigenmannia are of two types that have been designated tuberous and ampullary receptor organs. Parts of the lateral and basal surfaces of the receptor cells are in contact with accessory cells. A single relatively large, almost spherical, nerve ending is inserted between the basal end of each receptor cell and the subjacent accessory cell, lying within a hemispherical concavity in the base of the receptor cell.The presumed synaptic areas between each receptor cell and the nerve ending associated with it are not contiguous, but are morphologically discrete structures, separated by nonsynaptic areas of membrane (Fig. 1). Approximately thirty synaptic areas are found on each receptor cell in both kinds of organs. The surface contours of the apposed cell membranes are irregular in the nonsynaptic areas, and hence the extracellular space is variable in width. In the synaptic areas the membranes of both cells appear slightly thickened (Fig. 2), and are separated by a constant gap of about 200 Å. Fine fibrillar material spans the synaptic gap.

On the influence of weak electric currents and electrically charged surfaces on blood coagulation

The Journal of PhysiologyVolume 101, Issue 1 p. 27-35 ArticleFree Access On the influence of weak electric currents and electrically charged surfaces on blood coagulation F. Schütz, F. SchützSearch for more papers by this author F. Schütz, F. SchützSearch for more papers by this author First published: 02 June 1942 https://doi.org/10.1113/jphysiol.1942.sp003965Citations: 3AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume101, Issue1June 2, 1942Pages 27-35 RelatedInformation

Electrolytic recording of weak electric currents

Solutions for use in electrolytic recording are described which give dark-coloured permanent records. These solutions are about five times as sensitive as the starch iodide solution usually employed for this work.

The Lower Limits of Perception of Electrical Currents by Fish

In recent years attention has been given to the influence of electrical currents as fish deflectors or screens, and experiments have been made to determine the magnitude of the currents which are sufficient to paralyse or act as deterrents to fish which may enter the electrical field, but in such strong fields the perception of the mechanism by which fish respond to electric currents is masked by the paralysis produced. It seemed possible that experiments with very weak currents might give fuller information concerning the mechanism by which fish respond to electrical stimulus than those made in strong fields. There is also the possibility that weak electric currents may occur in nature to which fish respond, but before exploring that field of phenomena it is necessary to observe the behaviour of fish under the influence of very weak fields. McMillan found that the field (volts per inch) required to paralyse young salmon varied with the resistivity of the water; thus when the latter was 10,000 ohms per inch cube the paralysing voltage was about 1·5, so that a current density of ampere per square inch was sufficient to cause paralysis, whereas when the resistivity was twelve ohms per inch cube the current required was ·03 ampere. In the former case the conductivity of the fish was greater than that of the water, in the latter case less.

Note on the Sensitiveness of the Skin to Weak Electric Currents, as compared with the Sensitiveness of a Telephone to the same Currents

On 7th December last, I showed to the Society a method by which the skin might be stimulated by electric shocks from an induction coil corresponding in rhythm and intensity to the notes and chords of music given off by the phonograph. The pressures from the disk of the phonograph act on a variable resistance microphone transmitter. and the current passing through the latter also passes through the primary coil of an induction machine. From the secondary coil wires pass to two strips of platinum, immersed each in a beaker containing ·75 per cent. of salt solution. When the fingers are dipped into the salt solution, and the phonograph is set in motion, thrills are felt by the fingers corresponding to the intensity and rhythm of the music.Deeming it of interest to have some data regarding this experiment, I have modified it in the way shown in the diagram, and the E. M. F. of the battery employed and the resistances of the various pieces of the apparatus were measured. Into the circuit of the secondary coil, f, a resistance box, g, and a telephone, t, were introduced; and the circuit was completed when the fingers were immersed in the salt solution h, i. When the phonograph was in action and gave out a well-known military march, the thrills could be felt in the fingers, and at the same time the telephone, which was fixed in a stand at the level of the ear, gave out the music.