Sow-Hsin Chen is Professor Emeritus of Applied Radiation Physics, Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, specialising in the dynamics of soft condensed matter using thermal neutron, synchrotron x-ray, and laser light spectroscopy methods. Piero Tartaglia is a retired Professor of Physics, Department of Physics, University of Rome 'La Sapienza' and a former member of the Scientific Committee and the Physical Committee of the Italian National Research Council. His research focuses on dynamic properties of complex liquids and liquid systems.