Number 163 (Story #2), February 4, 1994 by Phillip F. Schewe and Ben Stein A TRANSITION BETWEEN SPIRAL AND BULLS-EYE STATES has been observed in Rayleigh-Benard convection experiments. Heating a thin fluid layer from below will cause cells to form which exhibit patterns such as hexagons, spirals, or bulls-eyes (target shapes). Research in this area has been crucial in understanding pattern formation in general. Scientists at the Weizmann Institute in Israel have been able to produce for the first time a continuous transition (at conditions very near to the gas-liquid critical point) between spirals and targets. Spirals and targets were even seen to co-exist, suggesting that there might be a common physical mechanism for producing the different patterns. Target and spiral spatio-temporal patterns turned up in a number of chemical and biological systems. For example, spiral electrical patterns have been measured in cardiac tissue. (Michel Assenheimer and Victor Steinberg, Nature, 27 Jan 1994.)