A systems theory with retroactivity: Application to transcriptional modules

In standard control systems theory, a system is modeled as an input/output (I/O) module with internal dynamics. This implicitly assumes that the dynamics of a module do not change when the module is connected to other components. However, such an assumption is not realistic in a wide number of electrical, hydraulic, mechanical, and biological systems. We thus propose a new model that incorporates signals that travel from downstream to upstream, which we broadly call retroactivity. We quantify such a retroactivity in transcriptional components and show how to attenuate its effect by the design of insulation devices.