Message systems evolution 409

We need to point additionally to the evolution of special organs, glands, which have stored chemical message systems to help coordinate activities and are associated with nerves and the brain (Figure 8.6 and Table 8.3). Glands are advantageous in organisation as chemical substations connected to different remote parts of the... 

The principle of evolution, to survive by adaptation, is also followed by the skin. Noxious effects on the skin surface and on stratum corneum are translated by signaling systems into messages for the epidermis and dermis. The response is the activation of endogenous protective agents. In the past several years the mechanisms of these protective responses have become better understood. This improved comprehension of a system as complex as the skin should translate into an improved practical treatment of the skin. The first generation of new products is indeed already in the market. 

Schema matching aims at identifying semantic correspondences between metadata structures or models, such as database schemas, XML message formats, and ontologies. Solving such match problems is a key task in numerous application fields, particularly to support data exchange, schema evolution, and virtually all kinds of data integration. Unfortunately, the typically high degree of semantic heterogeneity reflected in different schemas makes schema matching an inherently complex task. Hence, most current systems still require the manual specification of semantic correspondences, e.g., with the help of a GUI. While such an approach is appropriate for...

We can now examine the mechanisms of evolution. Earlier, we considered how variation is required for evolution. We can now see that such variations in living systems are changes that alter the meaning of the genetic message. These variations are called mutations. A mutation can be as simple as a change in a single nucleotide (called a point mutation), such that a... 

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