Expression array approach limitations

There are some important limitations to the expression array approach. Since this analysis examines only the transcriptome, it fails to identify the important regulatory points at the level of translation and enzyme activity [29], in addition to the processes of protein protein interaction. Currently, the expression arrays do not address the issue of alternative splicing, but there are new generations of arrays being produced to examine these events. 

The method for estimating parameters from Monte Carlo simulation, described in mathematical detail by Reilly and Duever (in preparation), uses a Bayesian approach to establish the posterior distribution for the parameters based on a Monte Carlo model. The numerical nature of the solution requires that the posterior distribution be handled in discretised form as an array in computer storage using the method of Reilly 2). The stochastic nature of Monte Carlo methods implies that output responses are predicted by the model with some amount of uncertainty for which the term "shimmer" as suggested by Andres (D.B. Chambers, SENES Consultants Limited, personal communication, 1985) has been adopted. The model for the uth of n experiments can be expressed by... 

Another means of expressing the fidelity of an optical system is in terms of its modulation transfer function. The modulation transfer function describes the ability of the optical system to accurately reproduce an object whose pattern of luminance varies in a sinusoidal manner. An optical system which can precisely duplicate the modulation pattern of the object in the modulation pattern of the image has a modulation transfer function equal to 1.0 this represents the performance of a perfect system. The greater the difference between the modulation pattern in the image compared with that in the object, the lower the modulation transfer function. In practice, the modulation transfer pattern is usually evaluated with a square-wave pattern produced by a periodic array of lines. The modulation transfer function approaches zero as the spatial frequency of the lines increases. The limiting resolution in terms of the modulation transfer function is... 

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