Functional Analysis modified methods

Figure 15.2 Target validation and functional analysis overview of the methods currently available to biological researchers. Modified from Blackstock (1999).

Besides the isothermal kinetic methods mentioned above, by which activation parameters are determined by measuring the rate of dioxetane disappearance at several constant temperatures, a number of nonisothermal techniques have been developed. These include the temperature jump method, in which the kinetic run is initiated at a particular constant initial temperature (r,-), the temperature is suddenly raised or dropped by about 15°C, and is then held constant at the final temperature (7y), under conditions at which dioxetane consumption is negligible. Of course, for such nonisothermal kinetics only the chemiluminescence techniques are sufficiently sensitive to determine the rates. Since the intensities /, at 7 ,- and If at Tf correspond to the instantaneous rates at constant dioxetane concentration, the rate constants A ,- and kf are known directly. From the temperature dependence (Eq. 32), the activation energies are readily calculated. This convenient method has been modified to allow a step-function analysis at various temperatures and a continuous temperature variation.Finally, differential thermal analysis has been employed to assess the activation parameters in contrast to the above nonisothermal kinetic methods, in the latter the dioxetane is completely consumed and, thus, instead of initial rates, one measures total rates. 

Another parametric routine implements a discriminant function by the method commonly called linear discriminant function analysis. It is nearly identical to the linear Bayesian discriminant, except that instead of using the covariance matrix, the sum of cross-products matrix is used. Results obtained with the routine are ordinarily very similar to those obtained using the linear Bayes routine. The routine implemented as LDFA is a highly modified version of program BMD04M taken from the Biomedical Computer Programs Package (47). 

Cognitive Work Analysis is comprised of five individual methods and the first, woik domain analysis (WDA), is the means by which this functional analysis can be performed. The work domain analysis phase involves describing or modeling the system in which the activity under analysis takes place. A work domain analysis is used to identify the functional purpose and structure of the work domain in terms of the overall system goals, the processes adopted, and the artifacts used within the system. In modeling a system in this way, the system constraints that modify activity within the work domain are specified. These constraints can of course greatly influence the selection of automation strategies and allocation of function. 

Polarization is the most common method for the determination of sugar in sugar-containing commodities as well as many foodstuffs. Polarimetry is apphed in sugar analysis based on the fact that the optical rotation of pure sucrose solutions is a linear function of the sucrose concentration of the solution. Saccharimeters are polarimeters in which the scales have been modified to read directiy in percent sucrose based on the normal sugar solution reading 100%. 

We have recently modified U7) one of the several radiochemical methods (U5) which have been used for surface electrochemistry investigations in order to characterize adsorption on well-defined, single crystal electrodes. Below, we will describe the technique and identify some challenging issues which we will be able to address. The proposed method is sensitive to a few percent of a monolayer at smooth surfaces, is nondestructive and simple to use. The radiochemical measurements can be made with all compounds which can be labelled with reasonably long-lived, preferably g- emitting radioisotopes. We believe this technique will fulfill the quantitative function in in situ surface analysis as Auger spectroscopy currently does in vacuum, ex situ characterization of electrodes. 

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