Electrical stimulus

For the catalytic oxidation of malonic acid by bromate (the Belousov-Zhabotinskii reaction), fimdamental studies on the interplay of flow and reaction were made. By means of capillary-flow investigations, spatio-temporal concentration patterns were monitored which stem from the interaction of a specific complex reaction and transport of reaction species by molecular diffusion [68]. One prominent class of these patterns is propagating reaction fronts. By external electrical stimulus, electromigration of ionic species can be investigated. 

However, there is a period of time following the absolute refractory period during which a premature electrical stimulus can be conducted, and is often conducted abnormally. This period of time is called the relative refractory period (Fig. 6-2).2 The relative refractory period corresponds roughly to the latter half of phase 3 repolarization on the action potential and to the latter half of the T wave on the ECG. If a new... 

Concerning drug delivery, electrically erodible polymer gels for controlled release of drugs have been prepared, and a measured release rate of insulin has been observed under electrical stimulus [69]. A suspension of zinc insulin in a mixed solution of poly(ethyloxazoline) and PMAA was formed into a gel by decreasing the pH of the suspension. The obtained complex gel with 0.5 wt% of insulin was attached to a woven platinum wire cathode which was 1 cm away from the anode and immersed in 0.9% saline solution. When a stepped function of electrical current of 5 mA was applied to the insulin-loaded gel matrix, insulin was released in a stepwise manner up to a release of 70%. The insulin rate measured was 0.10 mg/h. 

An electrical stimulus of sufficient current magnitude to depolarize all nerve fibres within a given nerve bundle. Commonly quoted as > 60 mA for transcutaneous nerve stimulation. 

Following the introduction of ECT, much of the early research focused on basic properties of the electrical stimulus. This work was largely abandoned following the introduction of psychopharmacological treatments in psychiatry, and there was little technical progress in the administration of ECT. In the last 15 years, there has been renewed research interest in this area, which has in turn led to modifications in treatment technique. 

A better understanding of the role played by the electrical stimulus itself... 

Electric Initiators, Activated, can be divided in 5 main classes basedon the type of transducer used for conversion of the electrical stimulus (a) resistive bridgewire, exemplified by electric blasting caps, squibs,... 

Explosives can therefore be classified by the ease with which they can be ignited and subsequently exploded. Primary explosives are readily ignited or detonated by a small mechanical or electrical stimulus. Secondary explosives are not so easily initiated they require a high velocity shockwave generally produced from the detonation of a primary explosive. Propellants are generally initiated by a flame, and they do not detonate, only deflagrate. 

Figure 3. Influence of LSD-25 on synaptic transmission in lateral geniculate body of the cat. The optic nerve is electrically stimulated about 250 times per second, leading to the repetitive complex response seen in A and B. T points to the presynaptic wave arriving in the geniculate nucleus. After a delay of less than one millisecond, the nerve cells are synaptically excited and produce spike S. The deflections occurring prior to wave T are the so-called stimulus artifacts, i.e., the electrically conducted disturbance elicited by the electrical stimulus they have no biological significance. A control record of five responses out of a larger series. B after 15 jjg of LSD-25 had been given via the carotid artery. Note drastic reduction of postsynaptic spike, S, signaling impairment of synaptic transmission. (See Evarts et al., 1955-)...

Neural cells from Aplysia Extracellular response on electrical stimulus [97]... 

Efforts should be made to use these drugs sparingly, and to check that their effects have worn off before the patient leaves the operating room. In fact, electric stimulation of a peripheral nerve (e.g., ulnar nerve) can be used to objectively determine if there is residual muscle paralysis.1 The muscles supplied by the nerve must show an appropriate twitch response to a given electric stimulus to insure that the patient has recovered adequately from the neuromuscular blocking drug.20,31... 

It also should be noted that the sensitivities of excitable cells to electric fields decrease rapidly as the electric stimulus is applied for time periods decreasingly short in comparison to the refractory period of the order of 1 msec. Hence, quotation of reported low frequency membrane sensitivities as done by Frey (35) carries no implication with regard to sensitivities claimed at microwave frequencies correspond to time periods of the order of 1 nsec, which is a million times smaller than the refractory period. More recently, it has been postulated (36) that microwave fields may well be perceived, provided they are modulated with frequencies below 10 or 20 Hz. This would be possible in principle if induced in situ fields and currents could be rectified with some degree of efficiency so that microwave fields would generate detectable low frequency currents. No evidence for such a mechanism has been demonstrated so far at the membrane level. 

The first action potential in this series was in response to an electrical stimulus. The... 

Once the electrical stimulus is delivered, a generalized brain seizure follows, of a variable duration of 30-90 seconds. Scientists believe that this seizure activity is the variable responsible for ECT s therapeutic benefits. The patient gradually awakens from anesthesia a few minutes later. There is some cognitive confusion, which usually clears over the next... 

I applied a brief train of 60-cyclc sine wave electrical current w hencvcr the animal entered one corner of the enclosure. The animal did not stav away from the corner, but rather came back quickly after a brief sortie which followed the first stimulation and came back even more quickly after a briefer sortie which followed the second stimulation. By the time the third electrical stimulus had been applied the animal seemed indubitably to be coming back for more. (Carlson, 2001, p. 457)... 

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