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Network Theory

  The Network Theory, in electrical engineering, permits the mathematical analysis of large electrical circuits (for example the vast network which supplies electrical power to millions of homes). Much early work in Network Theory concentrated on the development of electrical filters, first used in telephony in the 1910s. The theory permits large, complicated systems to be broken down into smaller sub-systems, with known boundary conditions, and solved. The overall system response is then determined by combining the result of the interaction between the sub-systems. A powerful development from network analysis theory is network synthesis, where the process begins with the mathematical equations representing the desired electrical functions, and produces the electrical circuit components and values required.

The main modern use of network theory and synthesis in electrical engineering is in Computer Aided Design (CAD), for example of microelectronic circuits. CAD enables complicated electrical circuits, having many thousands of components, to be designed and tested without having to be physically constructed, and this allows cost-effective, rapid design and development. For instance, development of modern silicon ‘chips’ was only made possible through the use of CAD simulation programmes which used network theory.

In the life sciences, Network Theory is the idea that the immune response is self-regulated by the interaction between antibodies and their idiotypes. The production of specific antibodies against non-self molecules (antigens) is a central function of the immune response and involves recognition at the molecular level leading to binding between antigen and antibody. It has been demonstrated experimentally that antibodies which recognize non-self molecules are seen by the immune system as being antigenic in themselves; this antigenicity is referred to as the idiotype and may stimulate the production of anti-idiotype antibodies which, theoretically, may have structural similarities to the original antigen. Furthermore, the anti-idiotype antibodies are themselves antigenic. Jerne\'s network theory suggests that such anti-idiotype interactions are responsible for immunoregulation by homeostatic mechanisms and by the amplification of the immune response to specific antigens. Direct experimental evidence for such a role is hard to obtain but the implications of the network theory have been accepted as important. RB AC

See also homeostasis; immunology.Further reading Ivan Roitt, Immunology.



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Other Terms : Convergence Theory | Spontaneous Generation | Psychoanalytic Theory Of Art
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