Dynamic similarity hypothesis

By virtue of Equation 31, the diffusion coefficient is classified with the parameters characterizing a system in nonequilibrium, i.e. with the dynamic parameters of the system. The behaviour of such parameters near the spinodal and critical point is called dynamic critical phenomena. To describe them, an approach in the fashion of the similarity hypothesis has proved to be very fruitful, this hypothesis in its application to the dynamic parameters being called a dynamic similarity hypothesis (Stanley, 1971). 

The scaled structure factor F(x) or F(x) characterizes morphological aspects of the growing pattern such as those shown in Fig. 2, while the size of the pattern at t is characterized by qm(t) or Am(t) (eq.2). If the pattern grows with the dynamical self-similarity at a given T and (t)> is invariant with t, F(x) is universal with t as shown schematically in Fig.3(b). Obtaining this universal scaling function F(x) confirms the validity of the dynamical scaling hypothesis. The... 

The hypothesis of dynamic similarity also yields a similar relationship (Halperin and Hohenbcrg, 1967 Stanley, 1971). 

In a possible hypothesis, Smirnov et al. have proposed that a transient process such as [MX4]3- + [MXj] - —> [MX,] 2- + [MXJs- is the electrically conducting process. Their concept may he similar to the dynamic dissociation model. 

An important question concerning energy trapping is whether its kinetics are limited substantially by (a) exciton diffusion from the antenna to RCs or (b) electron transfer reactions which occur within the RC itself. The former is known as the diffusion limited model while the latter is trap limited. For many years PSII was considered to be diffusion limited, due mainly to the extensive kinetic modelling studies of Butler and coworkers [232,233] in which this hypothesis was assumed. More recently this point of view has been strongly contested by Holzwarth and coworkers [230,234,235] who have convincingly analyzed the main open RC PSII fluorescence decay components (200-300 ps, 500-600 ps for PSII with outer plus inner antenna) in terms of exciton dynamics within a system of first order rate processes. A similar analysis has also been presented to explain the two PSII photovoltage rise components (300 ps, 500 ps)... 

The similarity of its bioactive and X-ray conformations had been anticipated on the basis of SAR data and of its structural homology to dictyostatin [125], Dictyostatin (Fig. 16) is another MT-stabilizing agent that competes with PTX and has a similar effect on MT dynamics [125], The preferred solution structure of the conformation-ally constrained dictyostatin overlays quite closely the tubulin-bound conformation of DDM, suggesting that they interact in a similar way with MT (Fig. 19). This hypothesis was further supported by the synthesis of a macrocyclic DDM/dictyostatin hybrid, that displays considerable antiproliferative activity [126],... 

Perhaps more important, however, are the initial studies of Van Beylen and his collaborators on the dynamics of dissociation of carboanionic species studied by the technique of electric field relaxation. With fluorenyl lithium in pure diethyl ether and added traces of tetrahydrofuran the overall rate constant for dissociation displays a negative activation energy, strongly suggesting that dissociation does not occur directly from contact on tight ion pairs, which are present in vast excess, but rather via a small number of solvent-separated species. This is important because under identical conditions loose ion pairs cannot be detected spectroscopically. Similarly, with polystyryl caesium in tetrahydrofuran the results point to the presence of a small concentration of loose ion pairs and seems to support the hypothesis of Lohr and Schulz. 

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