Effect of stimulus frequency and duty cycle on force and work in fish muscle

1992 ◽  
Vol 70 (6) ◽  
pp. 1135-1139 ◽  
Author(s):  
Eric A. Luiker ◽  
E. Don Stevens
Keyword(s):  
Duty Cycle ◽  
Work Values ◽  
Stimulus Frequency ◽  
Fish Muscle ◽  
Adductor Muscle ◽  
Pulse Frequency ◽  
Pulse Number ◽  
Lepomis Gibbosus ◽  
Stimulus Pulse ◽  
Maximum Work

Stimulus trains of varying pulse number and pulse frequency were applied to the isolated pectoral adductor muscle of the sunfish Lepomis gibbosus. The number of pulses varied from 1 to 70, and the pulse frequency varied from 10 to 500 Hz. Muscle was continuously cycled at 2 Hz, and work was measured directly. Maximum force (177 kN/m2) was achieved with a train of 30 pulses at 169 Hz. Maximum work of 9.1 J/kg (power of 18.2 W/kg) was achieved with a train of 30 pulses at 169 Hz and a duty cycle (fraction of the cycle during which the muscle is activated) of 35%. Work values increased with an increase in the number of pulses per train, up to a maximum of 30 pulses. Duty cycle was the most important parameter in obtaining maximum work. The effect of varying stimulus pulse frequency on work values could not be accurately predicted from force values alone. For example, work increased 8-fold from twitch to maximum, whereas force increased only 2.6-fold.

Effect of temperature and stimulus train duration on the departure from theoretical maximum work in fish muscle

1994 ◽  
Vol 72 (6) ◽  
pp. 965-969 ◽  
Author(s):  
Eric A. Luiker ◽  
E. Don Stevens
Keyword(s):  
Duty Cycle ◽  
Relaxation Times ◽  
Length Change ◽  
Fish Muscle ◽  
Effect Of Temperature ◽  
Temperature Sensitive ◽  
Theoretical Maximum ◽  
Train Duration ◽  
Stimulus Train ◽  
Maximum Work

The goal of the present study was to compare the effect of temperature on contraction kinetic parameters of fish muscle with its effect on oscillatory work. In particular we studied the effect of stimulus train duration or duty cycle (the fraction of the imposed length change that the muscle was stimulated). We compared the actual work done by the muscle with a theoretical maximum work loop that would be achieved if it were fully and instantaneously relaxed at the onset of shortening and fully and instantaneously relaxed at the onset of lengthening. Temperature had a small effect on force but a marked effect on contraction and relaxation times. Thus, work was more temperature sensitive than force. The effect of temperature on work could not be predicted by its effect on any one contraction kinetic parameter. To achieve maximum work at lower temperatures, the duty cycle must be decreased because of the longer relaxation time.

Control of the Pacemaker System of the Nervenet in the Sea Anemone Calliactis Parasitica

1974 ◽  
Vol 61 (1) ◽  
pp. 129-143
Author(s):  
I. D. MCFARLANE
Keyword(s):  
Sensory Feedback ◽  
Pulse Frequency ◽  
Pulse Number ◽  
Pulse Action ◽  
Conduction System ◽  
The Body ◽  
Optimum Frequency ◽  
Nerve Net ◽  
Slow Conduction ◽  
Calliactis Parasitica

1. The rhythm of spontaneous nerve-net pulses is reset by intercalated evoked nerve-net pulses. 2. The origin of spontaneous nerve-net pulses can shift during a burst. There seem to be many potential pacemakers, widely distributed throughout the body, but apparently absent from the tentacles. 3. If a spontaneous or evoked pulse in the endodermal slow conduction system (SS 2) occurs during a burst, the nerve-net pulse intervals are increased during a 15-30 sec period following the SS 2 pulse. Additional SS 2 pulses cause a further increase in pulse intervals. 4. Nerve-net bursts are followed by a sequence of muscular contractions. The size of the contraction shown by any muscle group depends on nerve-net pulse number and frequency, the optimum frequency being different for different muscles. It is suggested that the SS 2 pulse action on nerve-net pulse frequency can significantly alter the behavioural output of nerve-net bursts. The SS 2 activity may represent sensory feedback on to the nervous pacemakers.

Diaphragmatic blood flow in the dog

1986 ◽  
Vol 60 (2) ◽  
pp. 554-561 ◽  
Author(s):  
H. Bark ◽  
S. M. Scharf
Keyword(s):  
Blood Flow ◽  
Duty Cycle ◽  
Stimulus Frequency ◽  
Phase Flow ◽  
Transdiaphragmatic Pressure ◽  
Relaxation Phase ◽  
Duty Cycles ◽  
Tension Time ◽  
Phrenic Artery ◽  
Electromagnetic Flow Probe

In anesthetized mongrel dogs we measured the blood flow in the left phrenic artery (Qdi), using an electromagnetic flow probe, before and during supramaximal phrenic nerve stimulation (pacing). This was done at constant respiratory rate (24/min) but at three different stimulation frequencies at a duty cycle of 0.4 (20, 50, and 100 Hz) and at three different duty cycles at a stimulation frequency of 50 Hz (duty cycle = 0.2, 0.4, and 0.8). Qdi was unchanged during diaphragm contraction until transdiaphragmatic pressure (Pdi) was greater than approximately 11 cmH2O, whereafter it began to decrease, reaching zero at Pdi approximately 20 cmH2O. Thus, when Pdi was greater than 21 cmH2O, all flow occurred during relaxation. Qdi averaged over the entire respiratory cycle (Qt) was less at duty cycle = 0.8 than under the other conditions. This was because of decreasing length of relaxation phase rather than a difference of relaxation phase flow (Qr), which was maximal during all conditions of phrenic stimulation. During pacing-induced fatigue, Qt actually rose slightly as Pdi fell. This was due to an increase in contraction phase flow while Qr remained constant. The relationship between Qt and tension-time index was not unique but varied according to the different combinations of duty cycle and stimulus frequency.

Secretion of K and fluid by rat submaxillary during sympathetic nerve stimulation

1975 ◽  
Vol 229 (4) ◽  
pp. 1056-1061 ◽  
Author(s):  
LH Schneyer
Keyword(s):  
Steady Flow ◽  
Flow Rate ◽  
Sympathetic Innervation ◽  
Stimulus Frequency ◽  
Submaxillary Gland ◽  
Pulse Frequency ◽  
Initial Flow ◽  
Saliva Secretion ◽  
High Concentrations ◽  
Two Phases

Stimulation of the sympathetic innervation to rat submaxillary gland is known to evoke saliva which contains high concentrations of potassium (130-160 meq/liter). Relationships were examined between salivary [K] and several parameters of the stimulation, including pulse frequency and duration of the stimulus train and rate of flow of the evoked saliva. Secretion of sympathetically evoked saliva was found to occur in two phases. After stimulation was started, flow rate was relatively high initially, and then decreased to a lower, relatively steady value. Initial and steady flow rates were maximal when stimulus frequency was 10 Hz. Salivary [K] was lowest initially, and, at that time, was inversely related to flow rate. At steady flow, [K] was flow independent. While salivary [K] was lower during initial than during steady secretion, the rate of K secretion was initially higher. During the initial phase, K decreased in the gland, and this decrease was sufficient to account for the increased amount of K secreted in initial saliva and for the increased initial flow.

Pulse Frequency Measurement Circuit for Infrared Laser

2014 ◽  
Vol 898 ◽  
pp. 676-679
Author(s):  
Hong Lu Hou ◽  
Guang Ze Xin ◽  
Jing Jing Qi ◽  
Fei Li
Keyword(s):  
Real Time ◽  
Optical Glass ◽  
Frequency Measurement ◽  
Pulse Frequency ◽  
Pulse Number ◽  
Measurement Circuit ◽  
Power Laser ◽  
Photoelectric Conversion ◽  
Pin Photodiode ◽  
Conditioning Circuit

Frequency measurement circuit based on PIN photodiode was designed to detect laser parameters in real time. The light intensity is decayed by the optical glass fixed in the front of the laser capsule. Photoelectric conversion is achieved by the photodiode. After being processed through the conditioning circuit, the electricity signal is transfered to the microcontroller which calculates the pulse frequency by counting the pulse number in interrupt mode. This system is enable to monitor the state of high-power laser in real time. By testing the whole system, the frequency measurement precision turns out to be less than 0.02%. The sensitivity of this measurement circuit is higher than 0.9V/mW, while the response time is lower than 3ns.

Effect of stimulus train duration and cycle frequency on the capacity to do work in the pectoral fin muscle of the pumpkinseed sunfish, Lepomis gibbosus

1993 ◽  
Vol 71 (11) ◽  
pp. 2185-2189 ◽  
Author(s):  
Eric A. Luiker ◽  
E. Don Stevens
Keyword(s):  
Duty Cycle ◽  
Length Change ◽  
Lepomis Gibbosus ◽  
Pectoral Fin ◽  
Cycle Frequency ◽  
Pumpkinseed Sunfish ◽  
Train Duration ◽  
Stimulus Train ◽  
Length Changes ◽  
Time Required

The goal of our experiment was to elucidate the effect of stimulus duty cycle (the percentage of the cycle that the muscle was stimulated), phase (the relative timing of the imposed sinusoidal length change and stimulation), and muscle cycle frequency (the speed at which the muscle was cycled) on work and power in the pectoral fin muscle of a labriform swimmer, the pumpkinseed sunfish, Lepomis gibbosus. Stimulus train duration was varied from a twitch to a 40% duty cycle; cycle frequency was varied from 1 to 8 Hz. Work was calculated as the area of work loops produced by muscle contractions while the muscle was undergoing sinusoidal length changes. Maximum net work per cycle (6.2 J/kg) was produced at 1 Hz cycle frequency and a 32% duty cycle. Maximum power (26.7 W/kg) was produced at 5 Hz cycle frequency and a 16% duty cycle. As cycle frequency increased, the duty cycle and the stimulus train duration that produced maximum work decreased. The relatively long relaxation time compared with the length of time required to complete the whole cycle precluded the muscle from doing net positive work at high cycle frequencies.

Experimental Research on Electroforming Nano-ZrO2 Reinforced Cu-Matrix Composite Aided by Pulse Power

2018 ◽  
Vol 764 ◽  
pp. 95-105
Author(s):  
Zhong Wen Sima ◽  
Zhi Yong Li ◽  
Hong Bin Cui ◽  
Hun Guo
Keyword(s):  
Surface Morphology ◽  
Matrix Composite ◽  
Current Density ◽  
Duty Cycle ◽  
Pulse Frequency ◽  
Cathodic Current Density ◽  
Ultrasonic Power ◽  
Cathodic Current ◽  
Maximum Content ◽  
Cycle Pulse

Prepared the nanoZrO2 reinforced Cu-matrix composite by pulse electroforming. The effects of the content of nanoZrO2 particle in the casting solution, average cathodic current density, duty cycle, pulse frequency and ultrasonic power on the content of nanoZrO2 in the electroforming Cu-matrix composite have been studied. The microhardness and surface morphology of Cu-ZrO2 composite were analyzed. The experimental results demonstrate that the maximum content of nanoZrO2 in the electroforming Cu-ZrO2 composite is 2.94%, microhardness is 492 HV, which is significantly improved compared with pulse pure copper’s 337 HV, when the content of nanoZrO2 is 40 g/L, average cathodic current density is 4A/dm2, duty cycle is 0.2 , pulse frequency is 1100 Hz and ultrasonic power is 20w .The surface of composite prepared by pulse electroforming is more smooth, organization is denser, grain is finer and agglomeration of nanoZrO2 particles is fewer compared with Direct-current electroforming nanoZrO2 reinforced Cu-ZrO2 composite.

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