Zero latency

Applieation of proaetive systems has three dimensions (1) deployment, (2) completeness, and (3) timeliness. Deployment means that those entmsted with deeision making understand their roles in the process and how to aet on that information. Completeness means that all the information needed to make the deeision is accessible. Timeliness means that the information is available promptly enough to meet customer requirements. Zero latency is a term that describes the ideal with respect to timeliness. This means the delay between the occurrence of the event and its communieation to the deeision maker is instantaneous. The Department of Defense, a ehannel master, has actually set standards for latency. 

There is a characteristic temporal pattern in the occurrence of radiation-induced tumors following irra ation, a pattern that may be segmented into a latency period during which no excess is expressed, a period marked by a rise to a peak or a plateau that may be sustained, and a period of subsidence that may be absent. Only for leukemia and for bone cancer following uptake of radium-224 is this pattern well delineated a latency period of 2 to 4 years, a peaking at perhaps 6 to 8 years, and subsidence to near zero about 30 years after exposure. For other radiogenic cancers, the minimal latent period is less well defined and is generally taken to be 10 to 15 years. 

Fig. 9.13. Correlation of period and latency of Ca oscillations at different levels of stimulation, (a) The theoretical curve is obtained by integration of eqns (9.1) in response to step increases in /3 from zero to final values ranging from = 0.286 to j3c2 0.846 Vo - 1.4 (tM/min, v, = 6 p-M/min, - 65 p,M/min, Fm3 = 500 pM/min, Ajf = 1 min". A = 10 min" other parameter values are those of fig. 9.10 (Dupont et al, 1991). (b) Experimental results obtained in hepato-cytes by Rooney et al. (1989).

Fig. 9.14. Origin of the correlation between period and latency of Ca oscillations. The correlation is made clear by comparing oscillations in cytosolic Ca resulting from an instantaneous increase in at time zero, from jS = 0 up to the values 0.315 and 0.506. The curves, generated by integration of eqns (9.1) for the parameter values of fig. 9.13, show the shortening of both period and latency at higher stimulation, due to the faster accumulation of Ca between spikes (Dupont et ai, 1991).

The fact that Yq has a large value in the absence of stimulation in the one-pool model, in contrast to the two-pool model has consequences that might help to distinguish experimentally between the two situations. When increasing )3 in a stepwise manner from zero up to a finite value in the oscillatory range, the first Ca spike in the one-pool model occurs immediately regardless of the final value of /3 (fig. 9.21) the time between the stimulus and the first C i spike - i.e. the latency - is therefore very short compared with the period of oscillations. The reason is that the pool, filled to capacity before stimulation, discharges its content... 

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