The major change in the format of the fifth edition is the presentation of the book in two volumes, necessitated by the rapidly increasing knowledge of metabolism, interactions, and requirements of trace elements. The guiding principle was to present the minimum of results that would serve as a logical foundation for the description of the present state of knowledge.

This book provides a basis by which instruments and transducers can be selected, assembled and integrated with a computer to measure and control physical processes in an accurate and predictable manner. It consists of two parts, the first of which lays the theoretical foundation for the second. First the Fourier analysis of signals are summarized. Then, from a systems point of view, the following chapters introduce the important aspects of filters, amplifiers and analog-to-digital converters. The second half of the book first discusses in depth the importance of the timing of the computer with its instruments, transducers and actuators. It then summarizes the physical and functional aspects of transducers and actuators and gives numerous detailed examples of how they can be integrated into computer controlled experiments and processes.

This book is intended for physicists and chemists who need to understand the theory of atomic and molecular structure and processes, and who wish to apply the theory to practical problems. As far as practicable, the book provides a self-contained account of the theory of relativistic atomic and molecular structure, based on the accepted formalism of bound-state Quantum Electrodynamics. The author was elected a Fellow of the Royal Society of London in 1992.

M.J. Schwuger The Environmental Specimen Bank is a repository of representative environ mental specimens for safe long-term storage over decades and centuries without any chemical change in the constituents. It represents the modern form of a systematically designed collection which will permit comparative analyses and evaluations of chemicals in the future. The aims are: - the determination of selected chemical compounds at the time of storage, - comparative investigations with new methods for chemicals which, at the time of storage, could not be determined or were not recognized as important, - observation of trends in the environment using authentic material from the past and - documentation of long-term changes. Environmental specimen banking is thus suitable for identifying environmental changes and initiating necessary measures of remediation. It may be used to identify problems, study correlations between cause and effect and determine the effectiveness of legislative measures as well as to recommend the activities required. This is not only ecologically important, but also relevant for man, since he is the last member in the food chain and is therefore affected by all compartments of the environment. For this reason, two banking systems were established in Germany, one for environmental specimens (Jiilich), and the other for human specimens (Miinster).

At the Denver X-Ray Conference, the topic for the plenary lectures alternates annually between x-ray diffraction and x-ray fluorescence. This year is a "diffraction" year, and the theme is accuracy in powder diffraction. Instead of comprehensive cover age, such as was attempted at the Accuracy in Powder Diffraction Meeting held at the National Bureau of Standards in 1978, this meeting focuses on recent developments in measurement accuracy of two-theta and intensity. The focus on accuracy, from the practical point of view, is important in a wide range of x-ray diffraction measurements. Accu rate data improve our ability to identify phases in a mixture using the Powder Diffraction File. Improved accuracy is essential for better characterization of the lattice, crystallite size, strain and structure. Finally, the accuracy of quantitative analysis is of great concern in many laboratories. The five invited papers of the plenary session give a broad perspective of recent activity throughout the world on uses of more accurate data, on methods to achieve greater accuracy, and on fundamental factors affecting the accuracy. The scope of the conference, however, is much broader than that of the plenary session. The workshops lead off with many practical aspects of x-ray analysis. Many of the contributed papers expand on the theme of accuracy in x-ray powder diffraction. In particular, the s.ession on XRD quantitative phase analysis provides an exception al coverage of the limitations in quantitative analysis and of the techniques being employed to improve the results.