Fig. 1 Representative PRCs, PTCs, and limit cycle diagrams for Type 1 vs. Type O resetting. Figs. 1A, B, and C depict Type 1 resetting from Culex (F/Cq-1). Figs. 1D, E, and F depict Type O resetting from Drosophila (F/Dp-2). Figs. 1G, H, and I depict "critical stimulus" resetting from Gonyaulax (A/Gp-5). Figs. 1A, 1D, and 1G are PRCs, plotted as phase-shift (ordinate; advances positive, delays negative) vs. circadian time of stimulus onset (abscissa). Figs. 1B, 1E, and 1H are PTCs, plotted as "new" phase (ordinate; new phase=phase of clock after the phase-shift) vs. circadian time of stimulus onset (abscissa). Figs. 1C, 1F, and 1I are limit cycle diagrams, where the limit cycle is the circle with isochrons radiating from the central "singularity" point. The heavy dashed line is the resetting contour, i.e., the points on the phase plane to which state variables are changed by resetting stimuli. The resetting of state variables is depicted by the arrows from points on the limit cycle to points on the resetting contour.