Spiking behavior

With increasing values of S, as we pass the point marked by the black square, the fast subsystem undergoes a Hopf bifurcation. The complex conjugated eigenvalues cross the imaginary axis and attain positive real parts, and the stable focus is transformed into an unstable focus surrounded by a limit cycle. The stationary state, which the system approaches as initial transients die out, is now a self-sustained oscillation. This state represents the spiking behavior. 

As for a charged droplet, probably the most striking phenomenon is the spike behavior at the pole of a stretching droplet that ejects atomized droplets whose mass constitutes less than 1% of the parent droplet, but carrying more than one third of the total charges. This jetting of the spike occurs when the droplet charge exceeds... 

Fig. 18.13 Spike behavior at the tip of an electrified column, (a) Cross-sectional view of a 2D jet [3] showing the effect of initial deformation and (b) side view of an axisymmetric jet [70] showing the effect of charging level. The jet is disturbed at ka= 1.3 and bla = 10 (Courtesy of Elsevier)...

The activity concentrations of the longer-lived cesium isotopes s and Cs exhibit a spiking behavior during reactor shutdown which is virtually identical to that of the iodine isotopes this applies to PWRs as well as to BWRs. 

Because of the short radiative lifetimes of most electronically excited free atoms or molecules, the output power of many gas lasers does not show spikes, but follows quasistationarily the time dependence of the pump pulse. Since the relaxation rate of excited dye molecules is in the sub-nanosecond range, dye lasers also generally have no spiking behavior and Fig.11.1 applies to flashlamp-pumped arid laser-pumped dye lasers. 

In Fig. 5.2(f) (the highest stress) an early time current spike is apparent. Other records show this behavior more clearly. The impact-time spike shows... 

There is an interior optimum. For this particular numerical example, it occurs when 40% of the reactor volume is in the initial CSTR and 60% is in the downstream PFR. The model reaction is chemically unrealistic but illustrates behavior that can arise with real reactions. An excellent process for the bulk polymerization of styrene consists of a CSTR followed by a tubular post-reactor. The model reaction also demonstrates a phenomenon known as washout which is important in continuous cell culture. If kt is too small, a steady-state reaction cannot be sustained even with initial spiking of component B. A continuous fermentation process will have a maximum flow rate beyond which the initial inoculum of cells will be washed out of the system. At lower flow rates, the cells reproduce fast enough to achieve and hold a steady state. 

To validate the analytical procedure recovery experiments are performed. To this end, the CRM is spiked with a known mass of the analytes at a variety of concentration levels (at least three different levels) and the concentrations measured are compared to the expected concentrations in at least three separate experiments. The extraction step has been shown to be a critical step in the analytical procedure and it may be responsible for poor recoveries. The efficiency of this step can be assessed either by repetitive extraction of the sample or by the addition of internal standards prior to the extraction step with the assumption that the latter actually represent the behavior of the analytes of interest. 

NOTE Action potentials are represented as a pulse output from a spike-height discriminator Each vertical line represents one action potential. The firing rate of this neuron during similar pre-and postdrug behaviors is increased by injection of 1.0 mg/kg, SC, amphetamine. This increase occurs for both locomotion (from a mean of 28.3 to 39.0 spikes/sec) and face washing (fiom a mean of 43.7 to 46.5 spikes/sec). 

Isotopic double spike. The most rigorous approach is to use an isotopic double spike , in which samples are doped with a known quantity of spike Mo which consists of two isotopes in a known ratio (Wetherill 1964 Siebert et al. 2001). These spike isotopes serve as an internal standard to monitor mass fractionation of the sample subsequent to spiking. The fundamental advantage over the element spike is that the spike isotopes follow exactly the same fractionation behavior as the isotopes of interest. A disadvantage is the need to carefully prepare and calibrate the double spike. 

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