Astronomy helps advance medical diagnosis techniques   A cervical cancer cell about to divide. Courtesy: AP Photo/Imperial Cancer Research Fund.   Left: Photomicrograph of a 2nd generation 4 ´ 4 GaAs detector assembly. The device is die attached to the substrate, which in turn is mounted on a 2 stage Peltier cooler. Right: Photograph of the completed GaAs array/hybrid/substrate assembly. While such an array is too small for space science or medical applications it does allow issues related to pixel performance and inter-pixel communication to be studied. Note any large format device would also use a dedicated ASIC rather than specific components for the electronic readout chain of each pixel.   Release date: 28 November 2001