Extra Impulse Research Articles

S14-4 The unique role of community sport motivators in ‘connecting the dots’ in the Netherlands

Abstract Purpose In 98 % of all municipalities in the Netherlands, community sport motivators (in Dutch: Buurtsportcoaches) connect the dots between the sports sector, social sector, schools, care and childcare and even more. Their goal: motivating people of all ages to take up sport or become physically more active. Project description With now almost 6.000 of these professionals, their role is vital in Dutch sport policy and implementation, with tasks such as physical activity education, organizing events and activities, and advise clubs and childcare organizations. They work with local and social organizations and strengthen intersectoral collaboration. The implementation is coordinated on a national and local level and the co-funding is innovative: the government funds 40%, municipalities or local sport organisations 60%. The role of these professionals has been defined in national policies. One of the success factors is the fact that the tasks can be locally customized, according to the needs on a local level. Evaluation has been performed with quantitative and qualitative research. For instance, research shows that community sports coaches are responsible for both organising (95%) and supervising (86%) extracurricular sports activities at schools. A large majority (82%) of municipalities want to use community sports coaches to ensure that more children meet the exercise standard and that their motor skills improve. Conclusions Community sports motivators are here to stay in the Netherlands. Long-term sport policy is needed to build up the confidence in and capacities of this new sport professional. Their role is evolving: in the new National Sports Agreement (2022), strengthening implementation power is one of the targets. Community sports motivators will be more often deployed to organise or realise the referral of inactive people to the existing offer. And with the new School & Environment programme, the Dutch government is committed to equal opportunities by giving sufficient sports and exercise an extra impulse. This starts in the neighbourhoods where the most vulnerable children live, also lagging behind in sports and exercise participation. Among started schools, good examples are already visible where clubs, community sports coaches and commercial sport providers make an important contribution to children's development.

Comparative bioassay of silver nanoparticles and malathion on infestation of red flour beetle, Tribolium castaneum

BackgroundInsecticide resistance is the major threat in pest control management. Formulation with silver nanoparticle can be used as an alternative method to overcome these problems. Nanoparticles can provide a cheap and reliable source against Tribolium castaneum. The primary aim of our study is to compare the insecticidal efficacy of nanoparticles with commercial insecticide malathion.ResultsDue to the problems associated with the indiscriminate use of synthetic insecticides which promote the insect resistance, it is necessary to give an extra impulse to search alternative ways to control this pest. Silver nanoparticle can provide an accurate solution. In this study, the silver nanoparticles were synthesized, characterized and tested against the Tribolium castaneum. Characterization of the silver nanoparticles was done using ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The study was conducted to compare the mortality rate, ovipositional deterrent, repellent activity and antifeedent activity of different concentration of malathion, silver nanoparticles and the mixed suspension of silver nanoparticles and malathion against Tribolium castaneum. Results of all the assays clearly showed that the combination of silver nanoparticles with malathion shows high insecticidal efficacy.ConclusionDevelopment of resistance to the pesticide is acknowledged as the most serious problem in pest control. Nanotechnology can revolutionize agriculture and can provide a solution for pest management. The results from the study suggest that the silver nanoparticles have the pesticidal property which is an alternative solution for the insecticide resistance.

Experimental and numerical study on vibration of the full-revolving propulsion ship stern

In order to solve the severe vibration problems of an ocean engineering ship with a full-revolving propulsion system, the navigation tests, including forced vibration response test and modal test, are carried out in its stern. It is concluded from the comparison of the time-domain waveform and spectrum from different measurement points that three main factors lead to a high-level stern vibration. Firstly, the specific dynamic stiffness of a water tank is relatively small compared with its neighbor hold, which makes it act like a vibration isolator preventing vibrational energy transmitting to the main hold. Secondly, there exists high-density local modes in the working frequency range of the main engine and thus the local resonance occurs. Thirdly, the abnormal engagement of gears caused by the large deflection of the shaft bearing due to its low mounting rigidity leads to violent extra impulse excitations at high speeds. Then the modification against the dynamic defects is given by simply improving the specific stiffness of the water tanks. And the effect is validated by the FEM calculation. Some important experience is obtained with the problems being solved, which is useful in the design of ships with the same propulsion system. It is also believed that the dynamic consideration is as important as the static analysis for the ships, and that most of the vibration problems may be avoided with a proper acoustic design.

Does the 'coupled clock' make the heart tick?

This editorial refers to ‘Cardiac ryanodine receptors control heart rate and rhythmicity in adult mice’, by M. J. Bround et al ., pp. 372–380, this issue. The first written descriptions of the regular beating pattern of the heart (as measured by pulse) are found in the often fragmentary writings of the ancient Greek physicians and scientists.1 However, it was not until 1943 that the electrical events associated with the initiation of the cardiac impulse were first recorded in the vertebrate heart.2 Using extracellular electrodes, Emil Bozler reported that a local, slowly rising wave of negativity proceeded each impulse (extracellular action potential) in the sinus venosus of the turtle heart and in right atrial tissue prepared from a variety of mammalian species (rabbit, dog, and cat).2 He further demonstrated that this spontaneous activity was depressed by the application of acetylcholine. He used the term ‘pacemaker prepotential’ to describe these changes in membrane potential that led to cardiac action potentials. Interestingly, in the same paper, he also was the first to recognize that oscillations in membrane potential that occurred following an action potential (afterdepolarizations) could induce extra impulses. He concluded that ‘It is apparent that many rhythmic phenomena in cardiac muscle cannot be understood if only conducted impulses are recorded. It is quite possible, therefore, that local, graded activity which may take place in the ‘resting’ state offers the key to understanding of a variety of disturbances of the rhythmicity of the heart.’2 It has been nearly 70 years since this seminal study and yet the ionic/molecular basis of the cardiac pacemaker has not been …

Pharmacological treatment of hyperinsulineamia in rats depends on coping style

Passive and proactive coping styles are associated with marked differences in behavioral and neuroendocrine responses. Previous studies revealed that the passive individuals are more prone to hyperinsulineamia. Likewise, we hypothesize that different coping styles may require different drugs to treat this. We tested this by treating passive and proactive rats (Roman Low Avoidance and Roman High Avoidance rats respectively) with either Rosiglitazone or with RU486. After eight days of treatment we performed and intravenous glucose tolerance test (IVGTT) and we compared the insulin and glucose levels with those measured during the IVGTT at baseline. Rosiglitazone improved insulin levels during an IVGTT in both passive and proactive coping styles. RU486, however, lowered insulin levels only in rats with a passive coping style. This study suggests that insight in the neuroendocrine differences between passive and proactive coping styles may provide an extra impulse to improve treatment of insulin resistance, since it allows the application of drugs targeted at the individual.

Overcoming Load Discontinuity in Step-by-Step Solution of Shock Response

A scheme is proposed to overcome the discontinuity at the end of an impulse. This scheme is very simple in the step-by-step solution of shock response. The only change is the loading input at the time instant of load discontinuity in performing the step-by-step integration. The average value of the two discontinuity values at the integration point of load discontinuity is used to replace the use of one of them for loading input. The motivation of this change originates from the concept of no loading input error associated with the integration point of load discontinuity. The feasibility of this scheme is analytically explored. Analytical results reveal that this change in loading input will lead to no extra impulse and thus no extra displacement. Consequently, an accurate shock response can be computationally efficiently obtained. Two numerical examples are also used to confirm the analytical results. The scheme proposed will not increase any computational effort or complicate the dynamic analysis codes.

Sympathetic nerve stimulation produces spatial heterogeneities of action potential restitution

Restitution kinetics (RK) of action potential duration (APD) are classically studied by applying an extra impulse at varying diastolic intervals (DI) and might differ from RK elicited by sympathetic nerve stimulation (SNRK). To measure 'Physiological' RK during gradual increases in heart rate caused by sympathetic nerve stimulation (SNS) and its possible spatial heterogeneities caused by non-uniform innervation of the myocardium. The SNRK was measured from rabbit hearts with intact sympathetic innervation using optical mapping. APD versus DI were plotted from left ventricles during SNS, then with pacing using identical activation interval (AI) sequences. AI decreased (444 +/- 18 ms to 284 +/- 9 ms) in 25 s and recovered to baseline on SNS suspension (n = 10). APD versus DI plots were identical for SNS and pacing except that when maximum heart rate was reached, SNS elicited a further APD shortening compared with pacing. During SNS, APDs decreased from 216 +/- 9 ms to 154 +/- 7 ms (29% +/- 2%) at the base and from 206 +/- 12 ms to 158 +/- 7 ms (20% +/- 2%) at the apex. During pacing, APDs at the base decreased from 216 +/- 9 ms to 170 +/- 7 ms (21% +/- 1%, SNS versus pacing: P < .05). In contrast, RK were similar at the apex for SNS and pacing. During SNS, the extra APD shortening at the base was associated with longer segments of RK curves with negative slopes and extra DI prolongation. Perfusion with the I(Ks) inhibitor HMR 1556 (0.5 microM; n = 5) abolished differences in RK between SNS and pacing. Levels of KCNQ1 and tyrosine hydroxylase proteins were greater at the base than apex (n = 4), implying that apex-base distributions for I(Ks) and sympathetic innervation are congruent with SNRK heterogeneities. The findings shed further insights on heterogeneities of sympathetic nerves, RK, and the role of I(Ks) in cardiac repolarization.

A technique for overcoming load discontinuity in using Newmark method

Although a closed form solution can be obtained for the shock response to an impulse by using the Duhamel integral method for a single degree-of-freedom system, it is analytically verified herein that an extra amplitude distortion will be introduced at the end of the impulse by using the Newmark method. In fact, the relative amplitude error in the displacement response due to the discontinuity at the end of the impulse can be reliably estimated by the ratio of the area of extra impulse over the area of input impulse, where the area of extra impulse is equal to a half of the product of the time step and load discontinuity. It seems that the momentum equation of motion can be used to easily overcome the discontinuity problem at the end of an impulse. This is because the external force is replaced by its corresponding external momentum, which is obtained from the time integration of external force, and thus the discontinuity problem automatically disappears by using the momentum equation of motion. Numerical studies reveal that this technique is applicable to nonlinear systems. Meanwhile, it is also numerically illustrated that the discontinuity problem can be overcome by performing a very small time step immediately upon termination of the applied impulse.

Approach for Overcoming Numerical Inaccuracy Caused by Load Discontinuity

It was found that the discontinuity at the end of an impulse will lead to numerical inaccuracy as this discontinuity will result in an extra impulse and thus an extra displacement in the time history analysis. In addition, this extra impulse is proportional to the discontinuity value at the end of the impulse and the size of integration time step. To overcome this difficulty, an effective approach is proposed to reduce the extra impulse and hence the extra displacement. In fact, the novel approach proposed in this paper is to perform a single small time step immediately upon the termination of applied impulse, whereas other time steps can be conducted by using the step size determined from accuracy consideration in period. The feasibility of this approach is analytically explored. Further, analytical results are confirmed by numerical examples. Numerical studies also show that this approach can be applied to other step-by-step integration methods. It seems that to slightly complicate the programming of dynamic analysis codes is the only disadvantage of this approach.

Recognising F-response interference as a source of increased jitter in stimulated single fibre EMG

Objective To determine the source of an abnormal pattern of latency shifts leading to falsely high jitters in single fibre electromyography (SFEMG). Methods We observed a sudden shortening of the latency to an individual single fibre spike component followed by a gradual return to baseline values during stimulation single fibre electromyography (SFEMG) of the facial muscle. The pattern could be reproduced in healthy controls. Results The sudden decrease in latency proved to follow an additional discharge of the muscle fibre, not due to the external stimulus. This additional discharge was identified as an F-response. Conclusions The mechanism is thought to be a higher muscle fibre conduction velocity resulting from a temporary increase in stimulus frequency, in the form of an extra impulse along the muscle fibre represented by the F-response. Significance The typical abnormal pattern should be recognised because it can falsely increase the mean jitter. We advice to increase the time base to 50 ms if this pattern is observed and to exclude the affected potentials from jitter measurements.

Morphological and physiological properties of pheromone-triggered flipflopping descending interneurons of the male silkworm moth, Bombyx mori

1. The morphology of descending interneurons (DNs) which have arborizations in the lateral accessory lobe (LAL) of the protocerebrum, the higher order olfactory center, and have an axon in the ventral nerve cord (VNC), were characterized in the male silkworm moth, Bombyx mori. 2. Two clusters (group I, group II) of DNs which have arborizations mainly in the LALs were morphologically characterized. The axons of these DNs are restricted to the dorsal part of the each connective (Figs. 1–5). 3. Pheromonal responses of the group I and group II DNs were characterized. Flipflopping activity patterns, which have two distinct firing frequencies (high and low) in response to sequential pheromonal stimulation, were usually recorded (Figs.6–10). 4. Two types of flipflopping activity patterns were classified into those that had an antiphasic relationship (called the ‘FF’ type) between the left and right connectives and those with a synchronized relationship (‘ff’ type) (Figs. 8–12). We propose that some group II DNs show ‘FF’ flipflopping activity patterns (Fig. 10). 5. A state transition was usually elicited by less than 10 ng bombykol, the principal pheromone component. Extra impulses were elicited during constant light stimulation (Fig. 9). 6. Our results suggest that the LAL olfactory pathways might be important for producing flipflopping activity patterns (Fig. 11).

Activation mapping of reentry around an anatomical barrier in the canine atrium: observations during the action of the class III agent, d-sotalol.

In the chronically instrumented animal and the isolated blood perfused heart, atrial reentry via a fixed path around an anatomical obstacle has been described and is terminated by the Class III antiarrhythmic agent, d-sotalol. The precise mechanism by which d-sotalol terminates this arrhythmia is not known. In the present study, right atrial (RA) activation sequences in the isolated, coronary artery perfused canine heart during episodes of sustained flutter (n = 7) and drug administration were determined. A fixed array of bipolar electrodes was used to record endocardial electrograms from 96 sites on the RA simultaneously. Maps of all control flutters showed that the rhythm was due to persistent circus movement of the impulse around the tricuspid valve ring. D-sotalol was effective in terminating atrial reentry in this model. In all episodes, block of the excitatory impulse in a specific region of the reentrant circuit accompanied these terminations. However, the events preceding the occurrence of block of the impulse were not similar. Two different modes of termination are described. The Class III antiarrhythmic agent d-sotalol can terminate atrial reentry in several ways. In one mode, complete conduction block of the reentering impulse within the fixed path occurs to terminate the rhythm. In the other mode, interruption of the original reentrant circuit occurs when there is failure of a lateral boundary. Often in this latter case, interruption of the original circuit is by an extra impulse that is secondary to a change in the path of the impulse. In both modes cycle length oscillations are observed.

Using the eigenvalue expansion to solve for crack diffraction in an elastic waveguide with a numerical example of a surface crack on a railroad wheel rim

Surface waves are produced by hammer impact on the rim of a railroad wheel. They travel around the wheel tread. If a crack is present in the rim surface, there will be an extra impulse in the first arrival [M. N. Fahmy and R. D. Finch, J. Acoust. Soc. Am. 75, 1283–1290 (1984)]. The transient response of a railroad wheel to an impact force is obtained using the eigenvalue expansion method on the principal modes of the surface wave. The eigenfrequencies and corresponding displacement field for these modes are calculated by using the discrete collocation method. The crack echo diffraction is modeled using a planar cut in the back rim face. This type of crack occurs in 60% of the wheels withdrawn from service. Reflection off the crack face modifies results for the good wheel. The calculated and the measured frequency response of a 33‐in. railroad wheel with and without a 3/4‐in. surface crack are compared in the frequency range 0–15 kHz. [Work supported by the Association of American Railroads.]

Cepstrum analysis of surface waves in acoustic signature inspection of railroad wheels

Surface waves are produced by hammer impact on the rim of a railroad wheel. They travel around the wheel tread making one complete traverse of the circumference every millisecond. If a receiver is located close to the impact point the signal shows a series of arrivals at millisecond intervals. If a crack is present in the surface, there will be an extra impulse received in the first millisecond interval. Both contacting accelerometers and noncontacting microphones can be used to detect the signals. If the signals are digitized and processed in time, frequency, and quefrency domains, the presence of the crack can be seen most clearly by liftering the cepstrum to remove all but the initial reflection from the crack.

Cepstrum analysis of surface wave in acoustic signature inspection of railroad wheels

Surface waves are produced by hammer impact on the rim of a wheel. They travel around the wheel tread making one complete traverse of the circumference every millisecond. If a receiver is located close to the impact point, the signal shows a series of arrivals at millisecond intervals. If a crack is present in the surface, there will be an extra impulse received in less than a millisecond. Both contacting accelerometer and noncontacting microphones can be used to detect the signals. The signals were digitized and processed in time, frequency, and frequency domains and the presence of the crack can be seen most clearly by filtering the cepstrum to remove all but the initial reflection from the crack. [Work supported by ARE.]

Cone signals in the cat's retina.

1. The discharges of ganglion cells in the cat's retina were recorded under conditions intended to isolate the cone system.2. Stiles' two-colour threshold technique permitted the photopic system to be studied when at its highest sensitivity. The absolute sensitivity of a ganglion cell, expressed in equivalent photons of lambda(max) at the cornea per impulse discharged, was about 2500 times less when driven by cones than when driven by rods. This ratio improves to around 200 when allowance is made for the much smaller fraction absorbed by cones of photons incident on the cornea.3. The number of extra impulses discharged in response to a brief flash was approximately proportional to the number of photons in the flash, up to a limit.4. There was a region in the middle of the receptive field within which the area of a test spot and its illumination for threshold varied inversely. A flash extending over the peripheral part of the receptive field raised threshold above its minimum, presumably as a result of surround antagonism. Assessed from area-threshold curves, the balance of centre-surround antagonism in the photopic receptive field did not seem to depend upon background illumination.5. The threshold for a small (0.2 degrees ) flash confined to the middle of the receptive field was independent of background illumination until the background exceeded a particular level, the ;dark light' (I(o)). In different units this ranged about a mean of 7.89 log photons (560 nm equivalent) deg(-2) sec(-1). For backgrounds that exceeded I(o), threshold followed approximately Weber's law up to the highest illuminations that could be produced.6. With test flashes that filled the centre of the receptive field, the Weber fraction (test flash illumination/background illumination) in some units fell below 1%.7. Changes in the time course and latency of response accompanied the changes in sensitivity caused by alterations in background illumination. Responses of both X- and Y-cells became more transient and faster.8. The loss of sensitivity to a test flash brought about by a steady background light depended upon the size of that light. Sensitivity varied inversely with background area within a central region that matched closely the summing area for test flashes.

Intermittent ‘full’ upwelling in Lake Ontario

A strong enough longshore impulse leaving the coast to the left (looking downwind) generates ‘Full’ upwelling in which the thermocline comes to intersect the free surface. This problem is beyond the scope of linearized (small displacement) theory, but it may be treated as a simple geostrophic adjustment problem in which the wind stress is supposed to be exerted impulsively on a two-layer fluid. A minimum impulse is found to be necessary for a full upwelling to develop from hydrostatic equilibrium, the magnitude of which is close to the product of top layer depth and propagation velocity of long waves on the thermocline. When the upwelling-favoring wind impulse is greater than the minimum, the upwelled front moves offshore by a distance proportional directly to the extra impulse (above the minimum) and inversely to top layer depth times Coriolis parameter. Upwelling episodes observed in Lake Ontario during the International Field Year for the Great Lakes (IFYGL) and feasibility studies before IFYGL show a frontal behavior in good quantitative agreement with the simple theoretical model. The offshore component of the impulsively exerted wind leaves the position of the front unaffected. However, a sustained offshore wind increases somewhat the offshore displacement due to a prior longshore impulse. The effect is relatively weak, and an offshore wind alone rarely produces full upwelling. A sustained longshore wind acting on an already upwelled thermocline generates considerable negative potential vorticity. Adjustment following such a ‘second’ longshore impulse produces a more complex thermocline shape and under certain conditions a frontal countercurrent. In a closed basin, full upwelling following a wind stress impulse occurs over only a portion of the shoreline. Given quiescent conditions, the upwelled front may be expected to propagate alongshore, somewhat as an internal Kelvin wave. Observations in October 1972 in Lake Ontario show frontal motions resembling internal Kelvin waves. However, only one half of the wave propagates, that half in which particle velocities have the same direction as the wave propagation velocity. Furthermore, the propagating warm zone is much narrower than the cold upwelled zone which developed under a succession of previous wind impulses.

Inhibition of Impulse Activity in a Sensory Neuron by an Electrogenic Pump

THE CRAYFISH TONIC STRETCH RECEPTOR NEURON MANIFESTS THREE PHENOMENA: (a) Impulse frequency in response to a depolarizing current decays exponentially to half the initial rate with a time constant of about 4 sec. (b) One or more extra impulses superimposed on steady activity result in a lengthening of the interspike interval immediately following the last extra impulse which is proportional to the number of extra impulses. However, above a "threshold' number of impulses the proportionality constant becomes abruptly larger. (c) Following trains of impulses, the resting potential of the cell is hyperpolarized by an amount proportional to impulse number. Such posttetanic hyperpolarization (PTH) decays approximately exponentially with a time constant of 11 sec, but this varies with membrane potential. These effects are attributed to the incremental increase of an inhibitory (hyperpolarizing) current with a long (relative to interspike interval) decay constant. We suggest that this inhibitory current is the result of increased electrogenic Na pumping stimulated by Na entering with each impulse. Evidence is presented that the three effects are reversibly inhibited by conditions which depress active Na transport: (a) Li substituted for Na in the bath; (b) application of strophanthidin; (c) K removal; (d) treatment with cyanide; (e) cooling. We conclude that a single process is responsible for the three responses described above and identify that process as electrogenic Na pumping. Our observations also indicate that electrogenic pumping contributes to this neuron's resting potential.

Responses to single quanta of light in retinal ganglion cells of the cat

Under the best conditions, single ganglion cells of the cat's retina give one extra impulse (average) for less than 3 quanta (average) at the cornea. A stimulus containing about 15.50 quanta at the cornea is required to reliably modulate the maintained discharge. Calculations suggest that when a single quantum is absorbed in the retina several extra impulses must be initiated. This is confirmed by the statistics of the response. For quanta absorbed in receptors in the periphery of the receptive field fewer impulses result, and this is confirmed by reduced variability of response.

Relation of afferent nerve excitability to impulse generation in the frog spindle.

AbstractThe excitability properties of the sensory nerve and its finer branches in muscle spindle have been studied in isolated preparations using electrical stimulation of the nerve in conjunction with controlled extension of the spindle. Characteristic differences in recovery cycle were demonstrated between the trunk fibre and the intracapsular branches. The excitability of the afferent nerve was modified by stretch; during stretching there was a rise in excitability and a shortening of the recovery cycle in direct relation to the amount of stretch. These changes were related to the underlying receptor potential and to local currents in the nerve. In the aftermath of stretch the excitability of the nerve as tested with electrical shocks was raised This was in contrast to the depression in mechanical sensitivity as revealed by a test stretch. When an extra impulse was elicited by an electrical shock in the course of sustained stretch the succeeding spike train was shifted, its general pattern being unchanged. It appears that the interjected spike transiently wipes out the currents leading up to the generation of the succeeding spike and resets the impulse generating process. Considerations of the functional properties of the afferent fibre and its branches as found in the present study suggest that the sensory system of the muscle spindle acts in synchrony during stretch.