A sinusoidal signal is generally considered the simplest auditory signal. It is, indeed, a simple signal. However, it does not follow that a complex analysing device, like the cochlea, should treat a simple signal in a simple way. Indeed, a simple signal may appear to be complex when viewed from the standpoint of the device considered. Such an observation becomes cogent when one is attempting to discover the analysing capabilities of a device such as the cochlea, which appears designed to handle signals more complex than a sinusoid or multiple sinusoids.

In principle, there exist two ways to contribute to structure determination of macromolecules by X-ray diffraction: (a) by analysing diffraction data obtained from the crystalline state, and (b) by interpretation of X-ray small-angle scattering from particles in solution.

The brilliant achievements of X-ray crystal-structure analysis of macromolecules, initiated by the works of Perutz on heamoglobin and Kendrew on myoglobin, are well known and it is evident that its detailed elution of secondary, tertiary and quaternary structure cannot be matched by any other means. However, a number of necessary prerequisites for a successful application, as, for example, the availability of well-defined crystals and heavy atom labelled derivatives thereof to surmount the problem of phase determination are not always given.

Synchrotron radiation is intense electromagnetic radiation with a continuous spectral distribution emitted by high-energy electron (or positron) synchrotrons or storage rings in the visible, vacuum ultraviolet and X-ray regions. For a long time only an unwanted but inevitable by-product of ring accelerators in elementary particle research, synchrotron radiation is now becoming a most widely used tool in atomic, molecular and solid-state spectroscopy, surface physics, structural research on solids, soft X-ray microscopy, lithography. It is not yet clear how large the field of applications really is nor which line of research will prove to be the most fruitful one in the long run.