Recurring fragments

For simplicity, hereinafter one considers single-component adsorption where s — 2, i — A (a site is occupied), i — v (a site is free), and avpv — 1. The matrix method (MM) [17,19] may serve to either confirm or impugn the results obtained by MC. MM is based on a generally plausible assumption that the surface fragment with AMm sites can recur periodically along some direction. The MM analog of partition function (A. 1) is... 

FtG. 9. Peptide fragments recurring with the omission of certain residues. 

The experience reuse framework consists of the Process Data Warehouse, the process-integrated development environment PRIME, the Documentum repository, and a set of integrated tools, e.g., MOREX. This framework is able to specify the current problem situation based on the integrated rules, and tries to find a matching process trace or a recurring method fragment in the experience base of the PDW. 

Several studies have used automatic clustering methods in 0, y/ coordinate space to search for recurring loop conformations [25, 26, 27], If one considers all the possible Ramachandran regions theoretically accessible to each residue, less than one quarter of all possible conformers of a heptapeptide fragment are observed [28]. Indeed, Jones and Thirup [25] found that protein loops can usually be constructed from a small number of fragments of known structure. 

Over the years the priorities have been shifted several times. Initially the attention focused on the seco acid fragments and therefore on the stereocontrolled construction of the often recurring ff-hydroxycarbonyl and... 

Figure 23. Bal1-and-cage heart valves constructed with silicone elastomer balls. Compared to metal or rigid plastic balls, silicone elastomer balls create no noise as the heart beats. Problems from swelling and fragmentation of the balls which occurred in a few patients in the mid-1960 s were traceable to the processing techniques used in fabricating balls, and when once corrected the problems have not recurred. Silicone balls continue to be used in heart valves.

In the preceding example, the recurring mass difference of 28 mass units was used to relate two pair of peaks that perhaps could not have been otherwise recognized. Such recurring mass differences often appear and can be used to build the molecular structure piece by piece. Multicenter fragmentations in particular occur from fragment ions as well as molecular ions and thereby demonstrate which parts of the molecule are joined. 

If the upper-state PESs are purely repulsive, the dissociation process is direct and the excited molecule breaks apart on a very short timescale. No barrier hinders the fragmentation and the wave packet does not recur to the location where it originally started at t =0. The autocorrelation function shows no recurrences and, consequently, the absorption spectrum is featureless. ... 

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