Soon after the discovery of quantum mechanics, group theoretical methods were used extensively in order to exploit rotational symmetry and classify atomic spectra. And until recently it was thought that symmetries in quantum mechanics should be groups. But it is not so. There are more general algebras, equipped with suitable structure, which admit a perfectly conventional interpretation as a symmetry of a quantum mechanical system. In any case, a "trivial representation" of the algebra is defined, and a tensor product of representations. But in contrast with groups, this tensor product needs to be neither commutative nor associative. Quantum groups are special cases, in which associativity is preserved. The exploitation of such "Quantum Symmetries" was a central theme at the Ad vanced Study Institute. Introductory lectures were presented to familiarize the participants with the al gebras which can appear as symmetries and with their properties. Some models of local field theories were discussed in detail which have some such symmetries, in par ticular conformal field theories and their perturbations. Lattice models provide many examples of quantum theories with quantum symmetries. They were also covered at the school. Finally, the symmetries which are the cause of the solubility of inte grable models are also quantum symmetries of this kind. Some such models and their nonlocal conserved currents were discussed.

Distinct scientific communities are usually involved in the three fields of quasi-crystals, of liquid crystals, and of systems having modulated crystalline structures. However, in recent years, there has been a growing feeling that a number of common problems were encountered in the three fields. These comprise the need to recur to "exotic" spaces for describing the type of order of the atomic or molecular configurations of these systems (Euclidian "superspaces" of dimensions greater than 3, or 4-dimensional curved spaces); the recognition that one has to deal with geometrically frustrated systems, and also the occurence of specific excitations (static or dynamic) resulting from the continuous degeneracies of the stable structures considered. In the view of discussing these problems, aNA TO-Advance Research Workshop has assembled in Preveza (Greece), in september 1989,50 experts of the three considered fields (with an equal proportion of theorists and experimentalists). 35 hours of conferences and discussions have led to a more detailed evaluation of the similarities and of the differences in the approaches implemented in the studies of the three types of systems. The papers contained in this NATO-series book provide the substance of this workshop. The reader will find three types of papers. Some very short papers giving the main ideas stated on a subject. Papers comprising 8-10 pages which stick closely to the contents of the talks presented. Longer papers providing more extensively the background and results relative to a given topic. It is worth summarizing the principal outputs of the workshop.

The past three decades have been a period where useful current and voltage instabilities in solids have progressed from exciting research problems to a wide variety of commercially available devices. Materials and electronics research has led to devices such as the tunnel (Esaki) diode, transferred electron (Gunn) diode, avalanche diodes, real-space transfer devices, and the like. These structures have proven to be very important in the generation, amplification, switching, and processing of microwave signals up to frequencies exceeding 100 GHz. In this treatise we focus on a detailed theoretical understanding of devices of the kind that can be made unstable against circuit oscillations, large amplitude switching events, and in some cases, internal rearrangement of the electric field or current density distribution. The book is aimed at the semiconductor device physicist, engineer, and graduate student. A knowledge of solid state physics on an elementary or introductory level is assumed. Furthermore, we have geared the book to device engineers and physicists desirous of obtaining an understanding substantially deeper than that associated with a small signal equivalent circuit approach. We focus on both analytical and numerical treatment of specific device problems, concerning ourselves with the mechanism that determines the constitutive relation governing the device, the boundary conditions (contact effects), and the effect of the local circuit environment.

The interest in the problem of surface diffusion has been steadily growing over the last fifteen years. This is clearly evident from the increase in the number of papers dealing with the problem, the development of new experimental techniques, and the specialized sessions focusing on diffusion in national and international meetings. Part of the driving force behind this increasing activity is our recently acquired ability to observe and possibly control atomic scale phenomena. It is now possible to look selectively at individual atomistic processes and to determine their relative importance during growth and reactions at surfaces. The number of researchers interested in this problem also has been growing steadily which generates the need for a good reference source to farniliarize newcomers to the problem. While the recent emphasis is on the role of diffusion during growth, there is also continuing progress on the more traditional aspects of the problem describing mass transport in an ensemble of particles. Such a description is based on the statistical mechanical analysis of a collection of particles that mutually interact and develop correlations. An average over the multitude of atomistic processes that operate under these conditions is necessary to fully describe the dynamics in the system.

Since the early days of modem physics spectroscopic techniques have been employed as a powerful tool to assess existing theoretical models and to uncover novel phenomena that promote the development of new concepts. Conventionally, the system to be probed is prepared in a well-defined state. Upon a controlled perturbation one measures then the spectrum of a single particle (electron, photon, etc.) emitted from the probe. The analysis of this single particle spectrum yields a wealth of important information on the properties of the system, such as optical and magnetic behaviour. Therefore, such analysis is nowadays a standard tool to investigate and characterize a variety of materials. However, it was clear at a very early stage that real physical compounds consist of many coupled particles that may be excited simultaneously in response to an external perturbation. Yet, the simultaneous (coincident) detection of two or more excited species proved to be a serious technical obstacle, in particular for extended electronic systems such as surfaces. In recent years, however, coincidence techniques have progressed so far as to image the multi-particle excitation spectrum in an impressive detail. Correspondingly, many-body theoretical concepts have been put forward to interpret the experimental findings and to direct future experimental research. This book gives a snapshot of the present status of multi-particle coincidence studies both from a theoretical and an experimental point of view. It also includes selected topical review articles that highlight the achievements and the power of coincident techniques.

This volume represents the primary lectures of the NATO Advanced Study Institute (ASI) on "Nuclear Magnetic Resonance in Modern Technology," which was held at Sarigerme Park (near the Dalaman Airport) on the southern Aegean shore of Turkey from August 23 to September 4, 1992. As indicated in the title, this ASI was aimed at examining, displaying, and perhaps influencing, the role of nuclear magnetic resonance (NMR) in modern technological activity. The lectures summarized in this volume and the numerous short contributed talks and posters were primarily aimed at the question, "What is NMR doing in support of modern technology?" During the main discussion periods and the numerous small scheduled meetings of specific interest groups this same topic was also addressed, along with questions like, "What could or should NMR be doing in support of modern technology?" With this kind of subject orientation, the organizers attempted to include a large participation at the ASI from scientists and engineers from diverse private industries in which NMR does, or perhaps should, play a substantial role in supporting or optimizing technology. Perhaps because of a combination of worldwide industrial contractions and residual corporate nervousness regarding the then recent Gulf War (which caused a one-year postponement of this ASI), the participation from private industry was numerically disappointing. We hope that this book will serve to bring the role of NMR in modern industry to the attention of numerous industrial scientists and engineers who were unable to attend the AS .

The present volume contains the text of the invited talks delivered at the Eighth International Conference on Recent Progress in Many-Body Theories held at SchloB Seggau, Province of Styria, Austria, during the period August 22-26, 1994. The pro ceedings of the Fifth Conference (Oulu, Finland 1987), the Sixth Conference (Arad, Israel 1989) and the Seventh Conference (Minneapolis, USA 1991) have been published. by Plenum as the first three volumes of this series. Papers from the First Conference (Trieste, Italy 1978) comprise Nuclear Physics volume A328, Nos. 1 and 2, the Second Conference (Oaxtepec, Mexico 1979) was published by Springer-Verlag as volume 142 of "Lecture Notes in Physics," entitled "Recent Progress in Many Body Theories." Vol ume 198 of the same series contains the papers from the Third Conference (Altenberg, 1983). These volumes intend to cover a broad spectrum of current research topics in physics that benefit from the application of many-body theories for their elucidation. At the same time there is a focus on the development and refinement of many-body methods. One of the major aims of the conference series has been to foster the exchange of ideas among physicists working in such diverse areas as nuclear physics, quantum chemistry, complex systems, lattice Hamiltonians, quantum fluids and condensed matter physics. The present volume contains contributions from all these areas. th The conference was dedicated on the occasion of Ludwig Boltzmann's 150 birthday."

Semiconducting and Insulating Crystals details how absorption spectroscopy provides information on the nature, concentration, charge state and configuration of impurities in crystals and also on their kinetics and transformations under annealing. After an introduction of the bulk optical properties of semiconductors and insulators and of impurities in crystals, this book presents the physical bases necessary for the understanding of impurity spectra. The description of various set-ups and accessories used in absorption spectroscopy is followed by a presentation of experimental results on specific impurities and classes of impurities and their relation with those obtained by various computation and by other experimental techniques.

Nanometer CMOS RFICs for Mobile TV Applications focuses on how to break the trade-off between power consumption and performance (linearity and noise figure) by optimizing the mobile TV front-end dynamic range in three hierarchical levels: the intrinsic MOSFET level, the circuit level, and the architectural level. It begins by discussing the fundamental concepts of MOSFET dynamic range, including nonlinearity and noise. It then moves to the circuit level introducing the challenges associated with designing wide-dynamic range, variable-gain, broadband low-noise amplifiers (LNAs). The book gives a detailed analysis of a new noise-canceling technique that helps CMOS LNAs achieve a sub - 2 dB wideband noise figure. Lastly, the book deals with the front-end dynamic range optimization process from the systems perspective by introducing the active and passive automatic gain control (AGC) mechanism.

The individual papers that comprise this monograph are derived from two American Chemical Society (ACS) Fall National Meetings that focused on the current uses of synchrotron radiation (SR) research techniques. The first Symposium was held in Washington, DC, in August 1994, and the second convened in Chicago, IL, in August 1995. The intent of these symposia was to present a broad overview of several current topics in industrial, chemical, and materials-based SR research to a chemically inclined audience. The SR techniques covered were divided roughly into the three general fields of industrial, chemical, and materials science for this purpose. Included within these four categories are environmental, geologic, atomic/molecular, analytical, solid state physics, surface science, and biological applications of SR. There is little doubt that structural biology and environmental science are the largest growth areas in SR research as this monograph goes to press. The spirit of these symposia was to bring together the expert synchrotron radiation user with new and potential users of SR techniques. There are now a preponderance of particle storage rings, located throughout the world, devoted exclusively to the production of SR. There have been great improvements in the particle accelerators and storage rings from which SR emanates. These newest third generation SR sources are the result of the successful collaboration between SR users and accelerator physicists which has made a reality out of experiments never before possible.

Just over 25 years ago the first laser-excited Raman spectrum of any crystal was obtained. In November 1964, Hobden and Russell reported the Raman spectrum of GaP and later, in June 1965, Russell published the Si spectrum. Then, in July 1965, the forerunner of a series of meetings on light scattering in solids was held in Paris. Laser Raman spectroscopy of semiconductors was at the forefront in new developments at this meeting. Similar meetings were held in 1968 (New York), 1971 (Paris) and 1975 (Campinas). Since then, and apart from the multidisciplinary biennial International Conference on Raman Spectroscopy there has been no special forum for experts in light scattering spectroscopy of semiconductors to meet and discuss latest developments. Meanwhile, technological advances in semiconductor growth have given rise to a veritable renaissance in the field of semiconductor physics. Light scattering spectroscopy has played a crucial role in the advancement of this field, providing valuable information about the electronic, vibrational and structural properties both of the host materials, and of heterogeneous composite structures. On entering a new decade, one in which technological advances in lithography promise to open even broader horirons for semiconductor physics, it seemed to us to be an ideal time to reflect on the achievements of the past decade, to be brought up to date on the current state-of-the-art, and to catch some glimpses of where the field might be headed in the 1990s.

Proceedings of a NATO ASI/18th Course of the International School of Crystallography, held in Erice, Sicily, Italy, April 18--29, 199

Rapid thermal processing has contributed to the development of single wafer cluster processing tools and other innovations in integrated circuit manufacturing environments. Borisenko and Hesketh review theoretical and experimental progress in the field, discussing a wide range of materials, processes, and conditions. They thoroughly cover the work of international investigators in the field.

The workshop entitled Magnetic Susceptibility of Superconductors and other Spin Systems (S4) was held at Coolfont Resort and Health Spa. located near Berkley Springs West Virginia on May 20-23. 1991. There were over sixty attendees. approximately half from the United States. the remainder representing over twelve different countries. The international character of the workshop may be gleaned form the attendee list, included in this volume. The intent of the workshop was to bring together those experimentalists and theoreticians whose efforts have resulted in significant recent contributions to the development and use of the ac susceptibility technique as well as to the interpretation of data obtained from these measurements. Many spirited discussions occurred during and after the presentations. These are reflected in the manuscripts contained in these proceedings. Although camera ready manuscripts were required from all participants at registration, all manuscripts were revised and reflect the lively exchanges that followed each presentation. The small size of the workshop allowed the participants a high degree of flexibility. Consequently when a controversial topic such as "the irreversibility line" emerged, a special session was organized on the spot. At the suggestion of Ron Goldfarb, participants were invited to contribute a one page summary containing their thoughts on the topic. These stand alone contributions were retyped and included as submitted, with only minor editorial changes. These proceedings are intended for those experienced scientists new to the field and graduate students just beginning their research.

This conference is the second on the Science and Technology of Thin Film Superconductors. It proved to be an excellent forum for these specialists in thin film superconductivity. The conference, held April 30-May 4, 1990, in Denver, Colorado, hosted 170 researchers from 17 countries. The response to the conference again emphasized the need for a meeting devoted to the science and technology of thin film superconductors. The breadth of artic1es and advances made in this technology since the first conference in November 1988, reflect on the maturity of the topic. These proceedings contain artic1es on deposition methods by sputtering, e1ectron beam evaporation, resistive evaporation, laser ablation, chemical vapor deposition and electrodeposition, and on other studies related to substrates, thermodynamics of formation, grain boundaries and weak links, characterization, and some practical applications. The program committee was pleased with the quality of the publications and contributed articles. This conference was highlighted by a fuU day dedicated to presentations from the federallaboratories, discussing a wide range of topics on the fabrication, characterization, and theory of high-temperature superconductor thin films. Other highlights at the conference dealt with (1) critical parameters or problems in measuring critical current density and other important parameters, and (2) problems of scale-up, reproducibility, and amenability to device fabrication. It became evident from the presentations that three issues were developing into critical issues for the ultimate practical application of high temperature superconductor thin films."

Leading practitioners describe in detail advanced methods of mass spectrometry used in structural characterization of biomacromolecules of both natural and recombinant origin. They demonstrate by example how these methodologies can solve a wide array of real-world problems in protein biochemistry, immunology, and glycobiology, as well as for human bacterial pathogens, lipids, and nucleic acids. The book offers a unique opportunity to learn these techniques that are revolutionizing the field. Its authoritative assessment in the context of how to solve important and challenging problems in bioscience and medicine ensures a competitive advantage for today's researchers.

The NATO Advanced Research Workshop on Fundamental Aspects of Inert Gases in Solids, held at Bonas, France from 16-22 September 1990, was the fifth in a series of meetings that have been held in this topic area since 1979. The Consultants' Meeting in that year at Harwell on Rare Gas Behaviour in Metals and Ionic Solids was followed in 1982 by the Jiilich Inter national Symposium on Fundamental Aspects of Helium in Metals. Two smaller meetings have followed-a CECAM organised workshop on Helium Bubbles in Metals was held at Orsay, France in 1986 while in February 1989, a Topical Symposium on Noble Gases in Metals was held in Las Vegas as part of the large TMS/AIME Spring Meeting. As is well known, the dominating feature of inert gas atoms in most solids is their high heat of solution, leading in most situations to an essentially zero solubility and gas-atom precipita tion. In organising the workshop, one particular aim was to target the researchers in the field of inert-gas/solid interactions from three different areas--namely metals, tritides and nuclear fuels-in order to encourage and foster the cross-fertilisation of approaches and ideas. In these three material classes, the behaviour of inert gases in metals has probably been most studied, partly from technological considerations-the effects of helium production via (n, a) reac tions during neutron irradiation are of importance, particularly in a fusion reactor environ ment-and partly from a more fundamental viewpoint."

Provides a rigorous derivation of surface properties such as temperature and deformation using continuum mechanics; Discussion is animated by the authors' decades of experience in experimental mechanics; Includes many techniologically motivated problems, solutions and computer solutions

This monograph introduces the students and specialists of agricultural and food science to the fundamentals of optical spectroscopy, main principles of modern spectroscopic instrumentation, advantages and practical applications of spectroscopic methods to investigation of agricultural objects such as milk and dairy products, eggs, honey, animal hair, and agronomic plants.

Since the publication in 1950 of Vol. I, Spectra of Diatomic Molecules of Molecular Spectra and Molecular Structure, much progress has been made in the field. While there have been some important refinements in the theory of diatomic molecular spectra, most of the advances have been in the further exploration of individual spectra. Not only has the number of molecules about which some spectroscopic data are available been increased by a factor of 2 to 3, but also the spectroscopic information about the molecules known in 1950 has been vastly extended. This is due to the observation of new elec tronic states (about three times as many as known before), the enormous improvements in the accuracy of the constants of the states known in 1950, and the determination of higher order constants. In view of the increasing use of spectroscopic information on diatomic molecules in other fields of physics, in chemistry, and in astrophysics, it appeared desirable to prepare an up-to-date version of the table of molecular constants in the appendix of Vol. I. This updating proved to be far more time-consuming than originally anticipated, and it is only now, 10 years that we are able to present such a table, which, instead after its initiation, of the original 80 pages (plus 30 pages of bibliography), now fills a volume of 700 pages. In the interest of economy, and unlike the original version, the new table has been produced by photo-offset from the final manuscript."

In recent years, III-V devices, integrated circuits, and superconducting integrated circuits have emerged as leading contenders for high-frequency and ultrahigh speed applications. GaAs MESFETs have been applied in microwave systems as low-noise and high-power amplifiers since the early 1970s, replacing silicon devices. The heterojunction high-electron-mobility transistor (HEMT), invented in 1980, has become a key component for satellite broadcasting receiver systems, serving as the ultra-low-noise device at 12 GHz. Furthermore, the heterojunction bipolar transistor (HBT) has been considered as having the highest switching speed and cutoff frequency in the semiconductor device field. Initially most of these devices were used for analog high-frequency applications, but there is also a strong need to develop high-speed III-V digital devices for computer, telecom munication, and instrumentation systems, to replace silicon high-speed devices, because of the switching-speed and power-dissipation limitations of silicon. The potential high speed and low power dissipation of digital integrated circuits using GaAs MESFET, HEMT, HBT, and superconducting Josephson junction devices has evoked tremendous competition in the race to develop such technology. A technology review shows that Japanese research institutes and companies have taken the lead in the development of these devices, and some integrated circuits have already been applied to supercomputers in Japan. The activities of Japanese research institutes and companies in the III-V and superconducting device fields have been superior for three reasons. First, bulk crystal growth, epitaxial growth, process, and design technology were developed at the same time.