Excitable behavior

Hydrazine is absorbed through the skin. In one case attributed to hydrazine hydrate exposure, systemic effects included weakness, vomiting, excited behavior, and tremors the chief histologic findings were severe tracheitis and bronchitis, fatty degeneration of the liver, and nephritis. ... 

Nanowire profile also affects the excitation behavior of LSPs, i.e., it is one of the critical parameters that determine how electrons redistribute themselves in order to meet momentum matching condition. Effects of many profiles, such as rectangular, triangular, T and inverse T profiles, have been investigated [22, 23]. 

In describing this effect as an avalanche excitation mechanism, it is clear that the details of the process differ from those of the Photon Avalanche described in Sect. 9 since,being ultimately a single-ion effect, this mechanism does not involve runaway cross relaxation as an essential step, but is instead intimately related to temperature effects. Within the avalanche formalism, this mechanism is best described as a thermal avalanche, in which high excitation powers result in runaway sample heating rather than runaway cross relaxation. This mechanism is illustrated schematically in Fig. 17 a. The dashed fines in Fig. 17 a show the isothermal excitation behaviors for two internal sample temperatures, and... 

Herzberg, Gerhard. (1904-1999). A German-bom physicist who won the Nobel Prize for chemistry in 1971 for his work on the composition of molecules. His research involved the spectroscopy of atoms and molecules and their excitation behavior. He became a Canadian citizen and was the director of the Division of Pure Physics of the National Research Council of Canada. 

Matsumoto et al. [64] investigated gas occlusion in C g crystals by spectro-ellipsometry. They found that some oxygen remains in the voids (associated with polycrystals) in chemisorbed form. This is in contrast with the behavior of Cgg crystals in the presence of He, Ar, H2, or N2, where the spectra changed reversibly with pressure, in accordance with a physisorption model whereby gas molecules enter the voids and are occluded as a quasiliquid. Niklowitz et al. [65] studied the interaction of oxygen molecules with a fullerene surface using electron energy loss spectroscopy and TPD. On the basis of the vibrational excitation behavior, the authors concluded that molecular oxygen was physisorbed on Cgg under the conditions studied (20 K). In other words, the adsorbed molecules were only weakly perturbed by the Cgg substrate. 

In this context of excitation behavior and the relationship to the optical properties, it is important to mention the work of Demuth et who found new transitions which did not belong to the... 

As mentioned in Chapter 3, the type of excitable behavior discussed there may be considered as arising from a quasi-bistable dynamics in which one of the involved states, the excited one, is not really stable but lasts only for a finite time. Thus excitable diffusive systems have some similarities with bistable ones, but present an additional level of complexity. 

We finally mention that wave propagation arises from diffusion, but that the excitable behavior can give rise to interesting spatiotem-poral phenomena even without diffusion. For example, Matthews and Brindley (1997) show for model (4.32)-(4.33) with D = 0 that if there is a spatially localized forcing (a point source of nutrients, a local change in temperature, etc.), a localized excitation and recovery plankton pulse will occur, which may be a mechanism for localized (i.e. non-propagating) plankton blooms. 

Neufeld et al. (2002a) have shown that this behavior can be explained by the interplay between excitable plankton population dynamics and chaotic flow, similarly to the excitable behavior described in the previous section. In a chaotic flow a steady bloom filament profile can be generated, that does not decay until it invades the whole computational domain as an advectively propagating bloom. The condition for the existence of the steady bloom filament solution in the corresponding one-dimensional filament model is that the rate of convergence, quantified by the Lyapunov exponent, should be slower than the phytoplankton growth rate, but faster than the zooplankton reproduction rate. In this case the phytoplankton does not became diluted by the flow and the zooplankton is thus kept at low concentration unable to graze down the bloom filament. 

We mention that the interspike interval distribution densities for the FHN system in the different dynamical regimes, including excitable behavior, were already presented in [9]. The calculations were performed under the assumption of a perfect time scale separation and linearization of the... 

Crotonaldehyde canses severe irritation of the eyes, nose, Inngs, and throat. Exposnre to a concentration of 12 mg/m in air for 10 minntes can canse bnming of the Inngs and throat in hnmans. The symptoms of inhalation toxicity in rats were excitement, behavioral change, convnlsion, and death. The same symptoms were observed when crotonaldehyde was administered snbcnta-neonsly. 

The best introduction to ion channels and excitable behavior in cells can be found in Ion Channels of ExaVflWeMembranes, 3rd ed. by Bertil HiUe (Sunderland, MA Sinauer Associates 2001). 

In this model, e is the ratio of the time scales associated with the reactive dynamics of the two variables u and v, while D and are their diffusion coefficients. The parameters a and p characterize the local reactive dynamics. The FHN model was originally constructed as a simple scheme for describing electrochemical wave propagation in excitable nerve or cardiac tissue. The variable u corresponds to the potential while v represents ion currents in the nerve tissue. It has since been used extensively as a generic model that describes so-called excitable behavior of chemically reacting systems. In fact, as we shall show later in this chapter, it is possible to write a chemical reaction scheme whose rate law is of FUN form. ... 

In all five cases, therefore, there is, for apparently reasonable ranges of the parameters, a pseudo-steady state reduction of the kinetic equations to a pair of equations supporting relaxation oscillations or excitable behavior. If diffusion... 

Practically, to measure the excited state lifetime of an emitting sample, one has to measure the phase shift 8 and the modulation degree M at various frequency modulation of the exciting source. The measurement starts at a relatively high modulation frequency, at which, with the emission lifetime being faster than a single excitation wave, the emission profile matches the excitation behavior 8 — 0, M — 100%). Then, the modulation frequency is progressively increased and at a certain frequency the emission becomes shifted ( > 0) and the intensity decreases (M < 100%). 

Similar to the case of two-photon excitation, for multiphoton absorption the initiators would perform an operation of k y[n] with a much smaller coefficient k for w-photon absorption. The above two methods and knowledge acquired about the focal spot related to two or multiphoton excitation is essential for not only photopolymerization fabrication, but also important for understanding excitation behavior for various laser microfabrications. 

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