00347nam a2200121Ia 4500008004100000022001400041040001100055100002700066245005100093260005400144300001800198300000900216251112s9999||||xx |||||||||||||| ||und||  a0027-8424  aCNCLSA  aNicholas R. Cozzarelli 0aProceeding of the national academy of sciences  c1999bThe National Academy Of ScienceaWashington  aP.12211-13590  bV.96