Migration theory

A convenient concept for introducing the surface boundary condition into the mathematical formulation of migration theory is that of what may be called a diffusional offset length d. Suppose that the external and surface conditions are describable by a set of parameters X, which we do not need to specify in detail we also allow the surface conditions to depend on the internal hydrogen concentration just beneath the surface. If the hydrogen complexes that are continually forming in the crystal are sufficiently immobile, the balance between inflow and outflow across the surface will depend only on X and on the concentration no(0) of H0 just beneath the surface. (If mobile H+ or H are present, the statement just... 

In fluorescence spectroscopy, however, diffuse reflectance correction of spectral distortions in biological media has been studied extensively. Analytical models based on photon migration theory,44 diffusion theory46,60,61 as well as empirical models,62 have been reported to obtain intrinsic fluorescence. In the following, we will review a particular correction method based on photon migration theory for fluorescence spectroscopy and introduce its Raman counterpart. 

There is one theoretical treatment whieh deserves mention. The electron migration theory of Sklar has been applied by Baba and Nagakura (1483, 92, 91), Miyasaka (1418), and Tsubomura (2056). Miyasaka (91) considered an H bond system R=N—H- -O—X where the migrating electrons resonate between the unoccupied jth orbital j of the conjugated system R and the tt orbital f of a nonbonding electron of the substituent N. The final result of this perturbation treatment is a rather simple expression involving some quantities difficult to evaluate ... 

It is clear that there can be no compartmentalized theory of forced migration. Theory, in this area, means... 

Bakewell, O. (2010) Some Reflections on Structure and Agency in Migration Theory. Journal of Ethnic and Migration Studies 36(10) 1689-708. 

Indra, D. M. (1999) Not a "Room of One s Own" Engendering Forced Migration and Practice. Pp. 1-22 in D. M. Indra (ed.). Engendering Forced Migration Theory and Practice. Oxford Berghahn Books. 

Chapter 14 reviews modern migration theory as it applies to polymer extraction tests. Currently theory is being developed which given certain basic parameters of the polymer-extractant system would enable extraction data to be predicted theoretically thereby obviating the need for lengthy extraction tests. Eventually it is hoped that such an approach in certain cases might be accepted by the governing authorities. Much more work is needed in this field. 

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