SIRAS approach

For example, if we have another heavy atom isomorphous derivative available with heavy atom sites different from those found in the first derivative, when the preceding process is repeated, we will get two solutions, one true and one false for each reflection from the second derivative as well. The true solutions should be consistent between the two derivatives while the false solution should show a random variation. Thus, by comparing the solutions obtained from these two calculations, one (the computer) can establish which solution represents the true phase angle. This is the principle of the MIR method. One can also utilize the anomalous scattering (AS) data of the first derivative to resolve the phase ambiguity. In this case, the technique is called the SIRAS approach. If two derivatives and anomalous data are used, then it is called the MIRAS approach. 

Vcnkatcswarlu. A.. P. Sira A New Approach to the Microdciermination of Fluondc Adsorption-Diffusion Technique," Anal. Chemi. 43. 78 tt97l). 

This approach is known as single isomorphous replacement with anomalous scattering (SIRAS). Trigonometric equations can be derived... 

This leads us finally to the last approach, the literary analysis of the Isaiah narratives. Hand in hand with textual criticism, literary criticism aims to reconstruct the flow of tradition in the different versions of the Greek and Hebrew texts of Isaiah and 2 Kings (and also in the versions in 2 Chronicles, Josephus and Ben Sira). 

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