Word: gradient
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Dates: during 1990-1999
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...mutation caused younger cells to stop and not pass the older neurons. A gradient of increasingly older neurons toward the outside of the cortex resulted, which, according to Tsai, "effectively inverted the pecking order of the cortex...
...goes one step further: making an analogy between the events of the Cambrian explosion and the characteristics of a chaotic system. In so doing, you raise a disturbing question: Might not theoretical biologist Stuart Kauffman's idea of the intrinsic instability of the evolving system be greatest when the gradient of change is at its steepest? If so, is the closing paragraph of your report pointing out the precariousness of human existence in the face of the current technological ''big bang''? CHARLES F. (''CHICK'') KELLER Los Alamos National Laboratory Los Alamos, New Mexico Via E-mail...
...answer, according to a group of Harvard chemists, is a qualified "yes." In a collaborative effort, Mallinckrodt Professor of Chemistry George M. Whitesides '60 and Manoj K. Chaudhury of Dow Corning showed that water, pulled by a chemical gradient, can indeed travel upwards on a surface...