Many membrane-bound molecules in cells form small clusters. It has been hypothesized that these clusters convert an analog extracellular signal into a digital intracellular signal and that this conversion increases signaling fidelity. However, the mechanism by which clusters digitize a signal and the subsequent effects on fidelity remain poorly understood. Here we demonstrate using a stochastic model of cooperative cluster formation that sufficient cooperation leads to digital signaling. We show that despite reducing the number of output states, which decreases fidelity, digitization also reduces noise in the system, which increases fidelity. The tradeoff between these effects leads to an optimal cluster size that agrees with experimental measurements.
We describe the design and manufacture of a classroom set of devices that simultaneously measures and records the resistivity of four conductive elements (superconductor, semiconductor, metal alloy, and pure metal) as a function of temperature. The unique nature of this multi-semester project was that these devices would be designed, machined and assembled, and piloted in a local high school classroom by undergraduate service learning students.
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