Anomalous fading

This process leads to what is often termed "anomalous fading" (18). 

There are many complications to the method, including the anomalous fading exhibited by some materials and the variability of response by different materials, which means that the individual sensitivity of each sample to radiation must be determined. A number of different measurement techniques, involving the use of different fractions of the sample, have therefore been developed the measming laboratory will select the most appropriate. 

Fading Loss of luminescence during storage. Anomalous fading refers to loss in excess of the thermal fading predicted from measurement of the relevant electron trap depth and frequency factor. 

Some minerals (for example feldspar) from some sources exhibit anomalous fading namely, the observed lifetime is less than predicted by Eq. (2). The effect is because of an escape route not via the condnction band but directly to nearby centers. Two mechanisms have been proposed (1) a localized transition via an excited state common to both the trap and center, and (2) wave-mechanical tunnehng from the trap to the center. Reliable dating is not possible if (2) is dominant. 

Although anomalous diffusion is expected in fractal pore systems, the presence of anomalous diffusion does not prove that the porous media is fractal. A heterogeneity along transport pathways may result in an anomalous transport regardless of the presence or the absence of self-similarity of the pore space (Beven et al., 1993). The physical interpretation of Levy motions does not presume the presence of fractal scaling in the porous media in which the motions occur (Klafter et al, 1990). The applicability of the FADE may be closely related to the distribution of pore-water velocities. In saturated media, the presence of heavy-tailed distributions of the hydraulic conductivity directly implies the validity of the FADE (Meer-schaert et al., 1999 Benson et al., 1999). The heavy-tailed hydraulic conductivity distributions were found in geologic media (Painter, 1996 Benson et al., 1999). Heavy-tailed velocity distributions can also be expected in unsaturated and structured soils, and therefore the FADE may be a useful model in these conditions. 

The external force applied may enhance the anomalous transport in fractal structures (Roman et al., 1989). Therefore, anomalous features can be even more pronounced in the gravity-affected vertical water transport than in the horizontal water transport. General considerations of Roman et al. (1989) imply that the scaling variable x/f1 in (Eq. [2]) should be in this case replaced by the scaling variable xFiogit). Presence of sharp changes in soil hydraulic and transport properties that can be encountered during vertical flow in soils may make the dispersion/distance relations considerably more complex than they are in the media where the FADE has been shown to be effective. The efficiency of the FADE in such situations remains to be seen. 

The spin doubling in this molecule is anomalous. The parameter t is defined in a Fade type formula... 

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