Nature: Flexible rings that fold up on themselves into saddle shapes or stacks of interlinked loops are most recognizable in such everyday items as pop-up tents and laundry baskets. A group of researchers led by Alain Jonas of the Catholic University of Leuven in Belgium has determined that the way these rings behave depends on a single characteristic known as overcurvature, or how much more curved the ring is than a flat circle of the same circumference. By modeling overcurvature, the researchers were able to predict what shape a given ring would take and the path it would take to get there, which depends on how much energy was applied. A three-ring stack of interlocked loops required more energy at the start, but settled into position much more easily than forms that required less energy at the start. Jonas believes that his team’s findings regarding overcurvature may also apply to molecular rings such as plasmids or various polymers.