Lethargy variable

We conclude this section with a calculation of the frequency function in terms of the lethargy variable for the case of isotropic scattering in the center-of-mass system. The computation is carried out by transforming the energy function t (E Eo) given in (4.39) to the lethargy space by means of a relation of the type (4,33). We define... 

It can be demonstrated by means of a crude probability argument that these results (4.99) and (4.100) are indeed the nonabsorption probabilities defined above. For convenience, we will carry out the calculation in terms of the lethargy variable. Suppose that the interval 0 to w (which corresponds to the interval Eo to E) is divided into N subintervals Alii which are sufficiently small so that the cross sections may be given one particular value [2a(ui),2,(w<),. . . ] over each subinterval (see Fig. 4.17). Then let pi denote the probability that a neutron will pass through Aui without being absorbed. But, each must be an independent probability therefore,... 

The system defined by these assumptions is evidently one-dimensional and at steady state, and in this case the general Boltzmann relation reduces to a somewhat simpler form. The appropriate equation is obtained from (7.116) in terms of the lethargy variable this may be written... 

The signs and symptoms of early sepsis are quite variable and include fever, chills, and a change in mental status with lethargy and malaise. Hypothermia may occur instead of fever. Tachypnea and tachycardia are also evident. White blood cell count is usually elevated, as may be blood sugar. The patient may be hypoxic. Signs and symptoms of early and late sepsis are found in Table 45-2. 

Note that the lethargy integration is formally written for the interval (— 00,00). In point of fact, the variable u is defined for u > 0 thus we have implied that... 

The quantity X resulting from the separation of variables in (10.99) is determined by the application of boundary condition (2) in (10.100). For a independent of lethargy, the appropriate relation is found to be... 

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