content_image/337863.jpg content_image/337866.jpg content_image/337868.jpg content_image/337870.jpg content_image/337872.jpg content_image/337874.jpg
<img src='content_image/337863.jpg'>

(4). Then we fit the resulting curve to various functions. Based on least-square fit, best choice would be a mixture of polynomial and exponential functions, 

<img src='content_image/337866.jpg'>

where the coefficients read a = − 2 . 078 ± 0 . 117, b = 0 . 091 ± 0 . 007 and c = 17 . 332 ± 1 . 553, d = 0 . 189 ± 0 . 003, e = − 0 . 814 ± 0 . 162 and f = 2 . 849 ± 0 . 02. At small values of z , it is clear that the dependence is linear, 

<img src='content_image/337868.jpg'>

Obviously, the intersect c is much smaller than the slope C . The sign of g ( z ) can be flipped regarding to the sign of its independent variable z . Accordingly, we get 

<img src='content_image/337870.jpg'>

To prove this dependence, algebraically, we try to estimate g ( z ) directly from the division of F$_{0}$ by F$_{1}$ , which can be approximated by including their first terms only, i.e. 

Then, we approximate z ( H ) to the form, 

<img src='content_image/337872.jpg'>

<img src='content_image/337874.jpg'>

