Measurement of the electric field of the heart in a homogeneous volume conductor]

The paper describes a technique and some results of experimental measurements of electrical potentials generated by an isolated dog heart in homogeneous conductor, drawing equipotential maps of the field, and calculating the characteristics of the dipole equivalent generator of the heart. The form of potential distribution on a spherical surface around the heart and its ideal orthogonal vectorcardiograms are discussed.     

Basic Electrical Properties of Living Unstressed Rabbit Tibia

The presence of steady resting electrical potentials on the surface of living bone allows it, and other living tissues, to be considered as an electrical generator with a Thevenin equivalent circuit. By loading the generator component of bone with externally-applied resistors, fundamental electrical characteristics such as resistance, current, maximum generated power and power dissipated can be determined. This method has been applied to rabbit tibia.     

Reorganization of the efferent activity of the locomotor generator controlling forelimb movements for electrical stimulation of the descending systems

The reorganization of the parameters of the efferent activity of the forelimb locomotion generator for electrical stimulation of the descending systems is determined in experiments on decerebrate immobilized cats. This generator is found to be characterized by a stable state at which the sum of influences of the signals from different descending systems on the generator is extremely limited. It is concluded that under the influence of these signals, the reorganizations of the activity of the locomotion generators of different limbs bring the motor program into a dynamic (or nearly dynamic) relationship with the supraspinal inflow, allowing for a sufficient limitation and balancing of the influences of the corresponding descending systems on the interneuronal networks determining the temporal and phase characteristics of the activity of these generators.A. A. Bogomolets Institute of Physiology, Ukrainian Academy of Sciences, Kiev. Translated from Neirofiziologiya, Vol. 23, No. 6, pp. 704–708, November–December, 1991.     

Biophysical models of the heart electrical activity

Based on the fundamental knowledge of the space-temporal organization of extracellular electrical fields of the myocardium, a system for 3-D computer modeling of the cardiac electrical activity at different structural levels of the object is being developed at the Institute of Theoretical and Experimental Biophysics. The system is based on the earlier proposed and modified biophysical model of the electrocardiosignal genesis represented by a double electrical layer along the surface of the electrically active myocardium. The system combines the model for activation and repolarization of the heart ventricles; the advanced model for the evaluation of parameters of the cardiac electric field, which makes it possible to derive model electrocardiosignals both in the direct regime of calculation of the potentials and in the regime of calculation of electrocardiosignals from preliminarily determined components of the multipole equivalent electrical heart generator; a database for the model parameters and their combinations in the form of cards of simulated "patients", and a database of modeled electrocardiosignals. In the present paper (first from three within the framework of the problem), simulation methods in electrocardiology are briefly described and a biophysical model of the heart electrical activity is presented, which has made up the basis of the system for computer modeling of forward and inverse problems of the cardiac electric field. The parameters of the model are electrophysiological, anatomical, and biophysical characteristics of the heart.     

An electroejaculator for the collection of semen from the domestic cat

An electroejaculator for the collection of cat semen and for the evaluation of electroejaculation protocols is described. The electroejaculator contains an adjustable signal generator and allows for the precise control and monitoring of the electrical stimulus to the animal. The electroejaculator incorporates controls for the selection of the frequency, potential and waveform of the electrical stimulus and controls for either manual or automatic delivery of stimuli of specified characteristics to the rectal probe. In the automatic mode, the operator may also preset the rate and duration of stimulus application and the interval between successive stimuli. The electroejaculator output to the probe is controlled with an on-off foot-switch which allows for the collection of semen from an anesthetized cat by one operator. Diagrams of the functional block, the component circuits of the electroejaculator, and the accessories which facilitate the collection of cat semen are provided.     

Effects of Polarization of the Receptor Membrane and of the First Ranvier Node in a Sense Organ

It has previously been shown that the site of production of the generator potential in Pacinian corpuscles is the receptor membrane of the non-myelinated ending, and the site of initiation of the nerve impulse, the adjacent (first) Ranvier node. Effects of membrane polarization of these sites were studied in the present work. Nerve ending and first Ranvier node were isolated by dissection, electric activity was recorded from, and polarizing currents were passed through them. All observations were done at steady levels of polarization, seconds after onset of current flow. The following results were obtained: The amount of charge transferred through the excited receptor membrane is a function of the electrical gradients across the membrane. The generator potential in response to equal mechanical stimuli increases with resting potential of the receptor membrane. The refractory state of the generator potential is not affected by polarization. The electrical threshold for impulse firing at the first Ranvier node (measured by the minimal amplitude of generator potential which elicits a nodal impulse) is nearly minimal at normal resting potential of the node. Both, hyperpolarization and depolarization lead to a rise in nodal threshold. For any level of polarization of nodal and receptor membrane, the threshold for production of impulses by adequate (mechanical) stimulation appears determined by the generator potential-stimulus strength relation and by the electrical threshold of the node.     

Myocardial electrodynamics during electrical systole]

A dipole equivalent generator of heart is considered, which represents a circuit containing an active, capacitive and inductive resistance. The model makes it possible to solve a direct diagnostic task for the electric systole. A differential equation for the integral electrical vector of the heart in the dipole approximation was solved. A model vector electrocardiogram and a linear electrocardiogram for the electrical heart parameters are presented.     

Simultaneous chemical and electrical stimulation of labellar taste hairs of the blowfly Calliphora vicina

When recording from the tip of insect taste hairs, responses to chemical stimulation may be influenced by electrical currents, such as the preamplifier's input bias current. The effect of electrical currents on firing frequency of the salt receptor cell to KCl and NaCl stimulation was determined in labellar ‘aboral’ and ‘adoral’ taste hairs of the blowfly Calliphora vicina. Negative currents always decreased spike frequency, whereas positive currents either increased it, or did not change it significantly. Spike frequency changed less than 1% per 5 × 10^?11 A.A consistent picture of the electrophysiology of blowfly taste hairs is given. It includes a distal pore, present in the dendrite-free lumen of the hair. It abandons the concept of a generator current that transmits excitation from the distal, chemoreceptive part of the taste cell dendrite to the action potential generator in or near the taste cell body. The experimental results are interpreted on the basis of this picture. It is concluded that the ‘electrophoretic effect’ of the electrical current is very small. Thus, the measured effect should mainly be due to a ‘direct effect’ of electrical current on electrically excitable structures in the salt receptor cell, particularly in its dendrite.     

Dynamic control of the central pattern generator for locomotion

We show that an ongoing locomotor pattern can be dynamically controlled by applying discrete pulses of electrical stimulation to the central pattern generator (CPG) for locomotion. Data are presented from a pair of experiments on biological (wetware) and electrical (hardware) models of the CPG demonstrating that stimulation causes brief deviations from the CPG’s limit cycle activity. The exact characteristics of the deviation depend strongly on the phase of stimulation. Applications of this work are illustrated by examples showing how locomotion can be controlled by using a feedback loop to monitor CPG activity and applying stimuli at the appropriate times to modulate motor output. Eventually, this approach could lead to development of a neuroprosthetic device for restoring locomotion after paralysis. R. J. Vogelstein and F. Tenore contributed equally to this work.     

Experimental vestibulopathy produced as a result of formation of a generator of pathologically enhanced excitation in the vestibular nuclei (phenomenon of a determinative dispatch station)]

A possibility of formation of a generator of pathologically enhanced excitation in the system of the vestibular nuclei of the medulla oblongata by disturbance of their inhibitory processes (resulting in development of contralateral rotatory motions in animals) was shown. Experiments with electrical stimulation of the lateral vestibular nucleus and its coagulation showed the system of the vestibular neurons organizing the synchronous message by the vestibulo-spinal pathways to underlie the generator of the pathologically enhanced excitation. It was concluded that the generator of the pathologically enhanced excitation formed in the lateral vestibular nucleus as a result of disturbed inhibition underlied the hyperactive determinative dispatch station causing the syndrome of vestibulopathy     

Effects of Temperature on the Generator and Action Potentials of a Sense Organ

Charge transfer through the receptor membrane of the nonmyelinated ending of Pacinian corpuscles is markedly affected by temperature. The rate of rise and the amplitude of the generator potential in response to a constant mechanical stimulus increase with temperature coefficients of 2.5 and 2.0 respectively. The duration of the falling phase, presumably a purely passive component, and the rise time of the generator potential are but little affected by temperature. The following interpretation is offered: Mechanical stimulation causes the conductance of the receptor membrane to increase and ions to flow along their electrochemical gradients. An energy barrier of about 16,000 cal/mole limits the conductance change. The latter increases, thus, steeply with temperature, causing both the rate of rise and the intensity of the generator current to increase. The membrane of the adjacent Ranvier node behaves in a distinctly different manner. The amplitude of the nodal action potential is little changed over a wide range of temperature, while the durations of its rising and falling phases increase markedly. The electrical threshold of the nodal membrane is rather constant between 40 and 12°C. Below 12°C the threshold rises, and the mechanically elicited generator current fails to meet the threshold requirements of the first node. Cold block of nerve impulse initiation then ensues, although the receptor membrane still continues to produce generator potentials in response to mechanical stimulation.     

Investigation of burst generation by the electrically coupled cyberchron network in the snail Helisoma using a single-electrode voltage clamp

This paper describes the results of investigating burst generation by the cyberchron network in the snail Helisoma. The cyberchron network is composed of approximately 20 electrically coupled neurons and controls the feeding behavior of the snail. The electrical coupling between network members has made it particularly difficult to distinguish between the importance and involvement of single-cell and network properties in burst generation by this system. The present investigations utilized the new single-electrode voltage clamp to examine the membrane properties and network interactions of the cyberchron neurons: (1) A slow outward current is activated by moderately large depolarizing commands (?40 to 0 mV) and does not undergo inactivation decay (i.e., decline in magnitude) during a command potential step maintained for 10 sec or more. The lack of inactivation of the outward current in cyberchron neurons appears to be due to the dominating role of a Ca-dependent K current. (2) There are two functionally distinct classes of cyberchrons—current generator cyberchrons and follower cyberchrons. (3) Primary current generator cyberchrons have membrane properties similar to endogenous bursting neurons (e.g., persistent inward Ca current and negative resistance region in I–V plot) and appear to provide the main driving and timing current for the rest of the network. (4) The vast majority of cyberchrons are secondary current generator cyberchrons with membrane properties which exhibit inward-going rectification and appear to burst as a result of regenerative excitation with one another and the primary current generator cyberchrons. (5) The second class of cyberchrons are driven by the electrical synaptic input from the current generator cyberchrons, do not exhibit inward-going rectification, and are called follower cyberchrons. (6) Burst termination is due to activation of a slow outward tail current in most cyberchrons during the burst (probably Ca-activated K current) which causes a hyperpolarization in individual cyberchrons, terminating the burst. (7) Decay of the outward tail current causes the cyberchrons to depolarize, which activates the persistent inward Ca current in the primary current generator cyberchrons, starting the burst cycle anew.     

Effects of Negative-Charged Atmosphere on Micro-Organisms

In an attempt to reappraise the reported interactions between 'small negative ions'and microorganisms, it is concluded that occasional effects observed are most probably due to the mechanical removal of the cells induced by the electrical field produced by the ion generator.     

An EPROM-based programmable contour generator for use in flow cytometry

An erasable programmable read-only memory (EPROM) contour generator has been fabricated to produce contours for use in flow cytometry. Contours are analog waveforms representing the fluorescence or light-scatter intensity distribution along a cell or object. The generator has particular utility in the development and testing of slit-scan instrumentation and analysis algorithms. Contours are generated without the requirement of specimens or full operation of the flow instrumentation. The generator provides control of contour height, width, offset, and rate. The EPROM may be custom programmed to produce contours for specific test applications or for reproducing "real" contour events. The generator is useful in situations where constant repetitive contours of predetermined characteristics are required.     

Rearrangement of scratch generator efferent activity during electrical activation of descending systems

Effects of signals proceeding along descending pathways on parameters of scratch generator activity were investigated in decerebrate immobilized cats. Certain phase-linked alterations in these parameters were shown to occur under the effects of electrical activation of the main descending systems. The biggest increase in scratch cycle duration under electrical stimulation of Deiter's nucleus, the red nucleus, and pyramidal tract is produced when stimuli are applied during the first half of the aiming stage. Stimulation during the second half of the aiming phase and at the start of the scratching movement hardly affect the scratching cycle. The main increase in length of scratch cycle during electrical stimulation of the reticular gigantocellularis nucleus is noted when stimuli are presented during the second half of the aiming stage. Electrical activation of descending pathways during the latter induces a rise in intensity in this phase and reduced intensity of the actual scratching stage. Activation of the pathways during this scratching motion causes heightened intensity of the motion while hardly affecting intensity of the aiming phase. The principles of suprasegmental rectification of scratch generator operation are discussed.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 22, No. 3, pp. 300–309, May–June, 1990.     

Evidence that dirty electricity is causing the worldwide epidemics of obesity and diabetes

The epidemics of obesity and diabetes most apparent in recent years had their origins with Thomas Edison’s development of distributed electricity in New York City in 1882. His original direct current (DC) generators suffered serious commutator brush arcing which is a major source of high-frequency voltage transients (dirty electricity). From the onset of the electrical grid, electrified populations have been exposed to dirty electricity. Diesel generator sets are a major source of dirty electricity today and are used almost universally to electrify small islands and places unreachable by the conventional electric grid. This accounts for the fact that diabetes prevalence, fasting plasma glucose and obesity are highest on small islands and other places electrified by generator sets and lowest in places with low levels of electrification like sub-Saharan Africa and east and Southeast Asia.     

三通道电刺激仪的研制及对臂丛神经损伤的临床疗效

目的:研制可用于臂丛神经损伤治疗的三通道电刺激仪,并且将之应用于临床臂丛神经损伤患者,观察该仪器治疗臂丛神经损伤的临床效果。方法:由主控模块、显示模块、键盘模块、三个通道的电刺激发生器模块以及电源模块组成系统,可以连续交替释放脉冲刺激,针对不同神经和肌肉,选择不同的刺激位点。将60例臂丛神经损伤术后的患者随机分成试验组(30例)和对照组(30例),试验组术后第三周使用三通道电刺激仪治疗,对照组不做处理,患者术后随访6-12月后,观察患者上肢肩部、肘部功能恢复情况。结果:试验组治疗后上臂丛、全臂丛、下臂丛的肩部、肘部功能均好于治疗前,差异明显,均有统计学意义(P0.05);试验组上臂丛、全臂丛、下臂丛的肩部、肘部治疗效果均显著优于对照组,差异有统计学意义(P0.05)。结论:三通道电刺激仪可以有效地促进臂丛神经损伤后上肢功能的康复,可以对三组神经和肌肉交替进行电刺激,使用方便,并且便于携带,患者较为满意。     

Rational Design of Advanced Thermoelectric Materials

Advanced thermoelectric technologies can drastically improve energy efficiencies of industrial infrastructures, solar cells, automobiles, aircrafts, etc. When a thermoelectric device is used as a solid‐state heat pump and/or as a power generator, its efficiency depends pivotally on three fundamental transport properties of materials, namely, the thermal conductivity, electrical conductivity, and thermopower. The development of advanced thermoelectric materials is very challenging because these transport properties are interrelated. This paper reviews the physical mechanisms that have led to recent material advances. Progresses in both inorganic and organic materials are summarized. While the majority of the contemporary effort has been focused on lowering the lattice thermal conductivity, the latest development in nanocomposites suggests that properly engineered interfaces are crucial for realizing the energy filtering effect and improving the power factor. We expect that the nanocomposite approach could be the focus of future materials breakthroughs.     

Freely Shapable and 3D Porous Carbon Nanotube Foam Using Rapid Solvent Evaporation Method for Flexible Thermoelectric Power Generators

A rapid solvent evaporation method based on the triple point of a processing solvent is presented to prepare carbon nanotube (CNT) foam with a porous structure for thermoelectric (TE) power generators. The rapid solvent evaporation process allows the preparation of CNT foam with various sizes and shapes. The obtained highly porous CNT foam with porosity exceeding 90% exhibits a low thermal conductivity of 0.17 W m^?1 K^?1 with increased phonon scattering, which is 100 times lower than that of a CNT film with a densely packed network. The aforementioned structural and thermal properties of the CNT foam are advantageous to develop a sufficient temperature gradient between the hot and cold parts to enhance TE output characteristics. To improve the electrical conductivity and Seebeck coefficient further, p‐ and n‐molecular dopants are easily introduced into the CNT foam, and the optimized condition is investigated based on the TE properties. Finally, optimized p‐ and n‐doped CNT foams are used to fabricate a vertical and flexible TE power generator with a combination of series and parallel mixed circuits. The maximum output power and output power per weight of the TE generator reach 1.5 µW and 82 µW g^?1, respectively, at a temperature difference of 13.9 K.     

Features of spatial distribution of constant electric field potential in normal states and in disease

Special features of changes in human electrical field in some diseases were studied. Methods for the correction of the disease-induced changes in the intrinsic human field using an external current generator were developed.