Discriminant residual

In many process-design calculations it is not necessary to fit the data to within the experimental uncertainty. Here, economics dictates that a minimum number of adjustable parameters be fitted to scarce data with the best accuracy possible. This compromise between "goodness of fit" and number of parameters requires some method of discriminating between models. One way is to compare the uncertainties in the calculated parameters. An alternative method consists of examination of the residuals for trends and excessive errors when plotted versus other system variables (Draper and Smith, 1966). A more useful quantity for comparison is obtained from the sum of the weighted squared residuals given by Equation (1). 

Residual Current Even in the absence of analyte, a small current inevitably flows through an electrochemical cell. This current, which is called the residual current, consists of two components a faradaic current due to the oxidation or reduction of trace impurities, and the charging current. Methods for discriminating between the faradaic current due to the analyte and the residual current are discussed later in this chapter. 

The elucidation of the X-ray structure of chymotrypsin (Ref. 1) and in a later stage of subtilisin (Ref. 2) revealed an active site with three crucial groups (Fig. 7.1)-the active serine, a neighboring histidine, and a buried aspartic acid. These three residues are frequently called the catalytic triad, and are designated here as Aspc Hisc Serc (where c indicates a catalytic residue). The identification of the location of the active-site groups and intense biochemical studies led to several mechanistic proposals for the action of serine proteases (see, for example, Refs. 1 and 2). However, it appears that without some way of translating the structural information to reaction-potential surfaces it is hard to discriminate between different alternative mechanisms. Thus it is instructive to use the procedure introduced in previous chapters and to examine the feasibility of different... 

To examine the fitness of the kinetic model CAER used for study of the water effect, we conducted model discrimination using the kinetic data of 15% Co/Si02 by comparing values of the standard function of mean absolute relative residual (MARR), which is simply defined as... 

The second group of SH2 domain proteins discriminates less and selects mainly hydrophobic residues with a consensus sequence ... 

The results were indicative of the crucial role of the electric dipole moment of ligands and its interaction with the negatively charged residue Glu225 and, moreover, the dipole proved to be an useful observable for discriminating between substrate and inhibitor (Fig. 2.5). A striking correlation was found between the energetics associated with this interaction and the kcat values... 

Glutamate and sodium/lithium-induced conformational changes in the GLT-1 transporter have been detected by the altered accessibility of trypsin-sensitive sites to the protease (59). These experiments in GLT-1 shows that lithium can occupy at least one of the sodium ion binding sites, but lithium by itself cannot support coupled transport (59). Therefore, at least one of the sodium binding sites in GLT-1 discriminates between sodium and lithium. As described earlier, this contrasts with EAAC-1, where lithium is able to support uptake. It should therefore be possible to identify residues that are responsible for the sodium/lithium selectivity difference between EAAC-1 and GLT-1. 

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