. Design for a brain; the origin of adaptive behavior. Calculators; Central nervous system -- Mathematical models; Behavior; Brain -- physiology. 7/20 THE ULTRASTABLE SYSTEM break if its variables are driven far enough away from their usual values. Thus, machines with moving parts, if driven ever faster, will break mechanically; electrical apparatus, if subjected to ever higher voltages or currents, will break in insulation; machines made too hot will melt—if made too cold they may encounter other sudden changes, such as the condensation which stops a steam-engine from working below 100° C; in
. Design for a brain; the origin of adaptive behavior. Calculators; Central nervous system -- Mathematical models; Behavior; Brain -- physiology. 7/20 THE ULTRASTABLE SYSTEM break if its variables are driven far enough away from their usual values. Thus, machines with moving parts, if driven ever faster, will break mechanically; electrical apparatus, if subjected to ever higher voltages or currents, will break in insulation; machines made too hot will melt—if made too cold they may encounter other sudden changes, such as the condensation which stops a steam-engine from working below 100° C; in chemical dynamics, increasing concentrations may meet saturation, or may cause precipitation of proteins. Although there is no rigorous law, there is nevertheless a wide- spread tendency for systems to show changes of step-function form if their variables are driven far from some usual value. Later (S. 9/7) it will be suggested that the nervous system is not exceptional in this respect. Systems containing step-mechanisms 7/20. When a state-determined system includes a step-function among its variables, the whole behaviour can undergo a simplifica- tion not possible when the variables are all full-functions. Suppose that we have a system with three variables, A, B, S; that it has been tested and found state-determined; that A and B are full-functions; and that S is a step-mechanism. (Variables A and B, as in S. 21/7, will be referred to as main variables.) The phase-space of this system will resemble that of Figure 7/20/1 (a possible field has been sketched in). The phase-space no longer fills all three dimensions, but as S can take only discrete values, here assumed for simplicity to be a pair, the phase-space is restricted to two planes normal to S, each plane corresponding to a. Figure 7/20/1 : Field of a state-determined system of three variables, of which S is a step-function. The states from C to C are the critical states of the step-function for lines in the lower pla
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Keywords: ., bookcentury1900, bookpublishernewyorkwiley, booksubjectcalculato
