CONTROLLING STOCHASTIC RESONANCE. In some systems, such as radio receivers, turning up the volume in order to hear a faint signal amidst much noise usually only results in turning up the noise as well. However, in other systems increasing the amount of ambient noise actually enhances (up to a certain point) the signal-to-noise ratio through a complicated nonlinear cooperation between the system and detector. This effect, known to operate in neurons, lasers, and tunnel diodes, is called stochastic resonance: the noise fluctuations might be stochastic (meaning totally random) but the detection of a desired signal can be maximized by tuning the noise. Now, researchers at Georgia Tech (Bill Ditto, 404-894-5216, wditto@acl.gatech.edu) have not only adjusted the noise knob to advantage but also the detector threshold. This can make the signal-to-noise ratio even better, with a bearing on the study of how sensory systems such as touch or hearing can pick out faint signals. Conversely the extra control mechanism can be used to undo the stochastic resonance effect, which just might be a desirable step in, for example, military applications (jamming) or in the suppression of unwanted interactions between electromagnetic radiation and biological tissue. (Gammaitoni et al., Physical Review Letters, 7 June.)