Dynamical fluctuations local

In NMR work, spin-lattice relaxation measurements indicated a non-exponential nature of the ionic relaxation.10,11 While this conclusion is in harmony with results from electrical and mechanical relaxation studies, the latter techniques yielded larger activation energies for the ion dynamics than spin-lattice relaxation analysis. Possible origins of these deviations were discussed in detail.10,193 196 The crucial point of spin-lattice relaxation studies is the choice of an appropriate correlation function of the fluctuating local fields, which in turn reflect ion dynamics. Here, we refrain from further reviewing NMR relaxation studies, but focus on recent applications of multidimensional NMR on solid-ion conductors, where well defined correlation functions can be directly measured. 

O Sullivan DBD, Jones CE, Abdelraheim SR, Brazier MW, Toms H, Brown DR, Viles JH (2009) Dynamics of a truncated prion protein, PrP(113-231), from N-15 NMR relaxation order parameters calculated and slow conformational fluctuations localized to a distinct region. Protein Sci 18 410... 

Faivre, A., David, L., VassoUle, R., Vigier, G., Etienne, S., and Geissler, E., Electronic density fluctuations in disordered systems 1. Effect of thermal treatments bon the dynamics and local microstructure of poly(methyl methacrylate). Macromolecules, 29, 8387-8390 (1996). 

For inhomogeneously broadened line shapes it necessarily follows that no information about time-dependent fluctuations of the chromophore s transition frequency (which I will call spectral dynamics) can be obtained from the line shape itself. This does not mean that such dynamic fluctuations do not occur it simply means that either their amplitude is much smaller than the inhomogeneous line width or that their time scale is much longer than the inverse of the inhomogeneous line width. In either case these dynamic fluctuations are of great interest because they result from time-dependent changes in the local environments of chromophores, and hence can provide information about solid-state dynamics. 

The translational motions and spin dynamics of conduction electrons in metals produce fluctuating local magnetic hyperfine fields. These couple to the nuclear magnetic moments, inducing transitions between nuclear spin levels and causing nuclear spin relaxation. The translational motions of electrons occur on a very rapid time scale in metals (<10 s), so the frequency spectrum of hyperfine field fluctuations is spread over a wide range of w-values. Only a small fraction of the spectral intensity falls at the relatively low nuclear resonance frequency (ojq 10 s ). Nevertheless, the interaction is so strong that this process is usually the dominant mode of relaxation for nuclei in metallic systems, either solid or liquid. 

Equilibrium dynamics of vesicles comprises the dynamical fluctuations around locally stable mean shapes. Quantitatively, such fluctuations have been studied for quasi-spherical vesicles [29,61] and for prolate shapes in the vicinity of the budding transition [33]. A nontrivial example of dynamical equilibrium fluctuations has been observed at the prolate-oblate transition [62]. As the activation energy between the two locally stable shapes is just a few k T, occasionally thermal fluctuations are large enough to drive the vesicle into the other minimum. This system thus constitutes one of the few examples showing a thermally induced macroscopic bistability. 

In the previous sections time averaged measurements have been discussed. The velocity profiles suggest a continuous flow in time. It is well known that instationary flow caused by velocity fluctuations can lead to vibrations (Hardow et al. [4]) that might affect the silo structure. In order to visualize dynamic effects, local velocity fluctuations were determined. As the silo... 

Proceeding from the arguments stated above, the critical temperatures at which critical density fluctuations are reached were calculated. A (Ap/p) value for PS at 433 K was accepted. The calculation results are quoted in Table 1.3, from which it follows that T and (7 ) for a set of amorphous and semi-amorphous polymers are very close the greatest discrepancy of these temperatures does not exceed 6% [87, 88]. Let us note that in the considered case we are dealing with dynamic (shortliving) local order, which is frozen below T (T ) [9]. 

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