tten word are contemporary examples of non-spoken language. By contrast, `speech' refers to the particular auditory/vocal medium typically used by humans to convey language. Although speech and language are closely linked today, their component mechanisms can be analyzed separately. The evolution of language entailed complex conceptual structures, a drive to represent and communicate them, and systems of rules to encode them 7 . The evolution of speech required vocalizations of adequate complexity to serve linguistic needs, entailing a capacity for vocal learning, and a vocal tract with a wide phonetic range. The evolution of human speech might also have required perceptual specializations 8,9 , but this article focuses only on speech production. The neural basis of language remains dimly understood, and homologies between language and animal communication systems are, at best, arguable. The absence of clear animal homologs to human language makes it difficu

We review recent finite opacity approaches (GLV, WW, WOGZ) to the computation of the induced gluon radiative energy loss and their application to the tomographic studies of the density evolution in ultrarelativistic nuclear collisions.

First published as an Advance Article on the web 19th June 2001 Ab initio and DFT calculations on the structure and properties of over 98 molecules are reported. Properties calculated for the molecules are assessed for their ability to correlate and predict experimentally derived values of the polarity/polarizability parameter, n. Using multivariate linear regression and partial least squares methods, four properties stand out as predictors of n: the molecular dipole moment, the polarizability, the CHelpG atomic charges and the frontier molecular orbital energies. These properties correlate n to close to the standard deviation in a previously published fragmental approach. The partial least squares method is shown to result in signiÐcantly better predictions for an external validation set.