Many screening hits inhibit enzymes with steep dose-response curves, which are considered pathological. Three models might explain these curves: multisite binding, an inhibitor phase transition, or stoichiometric inhibition caused by a high enzyme to Kd ratio. Experiments with promiscuous aggregators, for which steep curves are common, suggest that these curves owe to stoichiometric inhibition,...

Consider a classical two-dimensional scattering problem: a ray is scattered by a potential composed of several tall, repelling, steep mountains of arbitrary shape. We study when the traditional approximation of this nonlinear far-from-integrable problem by the corresponding simpler billiard problem, of scattering by hard-wall obstacles of similar shape, is justified. For one class of chaotic sc...