Nature is characterized by a number of physical laws and fundamental dimensionless couplings. These determine the properties of our physical universe, from the size of atoms, cells and mountains to the ultimate fate of the universe as a whole. Yet it is rather remarkable how little we know about them. The constancy of physical laws is one of the cornerstones of the scientific research method, but for fundamental couplings this is an assumption with no other justification than a historical assumption. There is no 'theory of constants' describing their role in the underlying theories and how they relate to one another or how many of them are truly fundamental. Studying the behaviour of these quantities throughout the history of the universe is an effective way to probe fundamental physics. This explains why the ESA and ESO include varying fundamental constants among their key science drivers for the next generation of facilities. This symposium discussed the state-of-the-art in the field, as well as the key developments anticipated for the coming years.

The origin of optical methods for fluid flow investigations appears to be nontraceable. This is no matter for surprise. After all seeing provides the most direct and common way for humans to learn about their environment. But at the same time some of the most sophisticated methods for doing measurements in fluids are also based on light and often laser light. A very large amount of material has been published in this area over the last two decades. Why then another publication? Well, the field is still in a state of rapid development. It is characterised by the use of results and methods developed within very different areas like optical physics, spectroscopy, communication systems, electronics and computer science, mechanical engineering, chemical engineering and, of course, fluid dynamics. We are not aware of a book containing both introductory and more advanced material that covers the same material as presented here. The book is the result of a compilation and expansion of material presented at a summer school on Optical Diagnosticsfor Flow Processes, held at RiS0 National Laboratory and the Technical University of Denmark in September 1993. The aim of the course was to provide a solid background for understanding, evaluating, and using modem optical diagnostic methods, addressing Ph. D. students and researchers active in areas of fluid flow research. The disciplines represented by the participants ranged from atmospheric fluid dynamics to biomedicine

Seldom does a physical system, particularly one as apparently simple as the flow of a Newtonian fluid between concentric rotating cylinders, retain the interest of scientists, applied mathematicians and engineers for very long. Yet, as this volume goes to press it has been nearly 70 years since G. I. Taylor's outstanding experimental and theoretical study of the linear stability of this flow was published, and a century since the first experiments were performed on rotating cylinder viscometers. Since then, the study of this system has progressed enormously, but new features of the flow patterns are still being uncovered. Interesting variations on the basic system abound. Connections with open flows are being made. More complex fluids are used in some experiments. The vigor of the research going on in this particular example of nonequilibrium systems was very apparent at the NATO Advanced Research Workshop on "Ordered and Turbulent Patterns in Taylor Couette Flow," held in Columbus, Ohio, USA May 22-24, 1991. A primary goal of this ARW was to bring together those interested in pattern formation in the classic Taylor Couette problem with those looking at variations on the basic system and with those interested in related systems, in order to better define the interesting areas for the future, the open questions, and the features common (and not common) to closed and open systems. This volume contains many of the contributions presented during the workshop.

These are the proceedings of the 141h Winter \Vorkshop on Nuclear Dynamics, the latest of a serif'S of workshops that was started in 1~)78. This series has grown into a tradition. bringing together experimental and theoretical expertise from all areas of the study of nudear dynamics. Following tllf' tradition of the Workshop the program covered a broad range of topics aerof'S a large energy range. At the low energy end llluitifragmentation and its relationship to the nuclear liquid to gas phase transition was disclIssf'd in grf'at df'- tail. New pxpf'rimental data, refined analysis techniques, and new theoretical effort have lead to considerable progress. In the AGS energy range we see the emergence of systematic data that contribute to our understanding of the reaction dynamics. The workshop also showf'd that at CERN energies Itadronic data become much more precise and complet.e and a renewed emphasis on basic hadronic processes and hadronic struc- ture as a precondition to understand the initial conditions and a basis for systematic comparisons. Wolfgang Bauer Michigan State Univcr'sity Hans-Georg Ritter Lawrence Berkeley National Laboratory v PREVIOUS WORKSHOPS The following table contains a list of the dates and locations of the previous Winter Workshops on Nuclear Dynamics as well as the members of the organizing committees. The chairpersons of the conferences are underlined.

The seventh Advanced Study Institute (ASI) on Techniques and Concepts of High Energy Physics was held for the second time at the Club St. Croix, in St. Croix, U.S. Virgin Islands. The ASI brought together a total of 75 participants, from 19 countries. The primary support for the meeting was again provided by the Scientific Affairs Division of NATO. The ASI was cosponsored by the U.S. Department of Energy, by Fermilab, by the National Science Foundation, and by the University of Rochester. A special contribution from the Oliver S. and Jennie R. Donaldson Charitable Trust provided an important degree of flexibility, as well as support for worthy students from developing countries. As in the case of the previous ASIs, the scientific program was designed for advanced graduate students and recent PhD recipients in experimental particle physics. The present volume of lectures should complement the material published in the first six ASIs, and prove to be of value to a wider audience of physicists.

The aim of the workshop was to bring together specialists in various fields where non-exponential relaxation is observed in order to compare models and experimental results and to examine the general physical principles governing this type of behaviour. Non-exponential relaxation is found in extremely diverse physical systems all of which can be classified as complex. The form of the relaxation is generally parametrized using logarithmic, algebraic or stretched exponential decay forms. The conceptually simplest mechanism for the non-exponential decay is a spectrum of relaxation rates due to non-interacting units each of which relaxes with a different intrinsic time constant. Clear experimental examples can be given where for instance the relaxation of a collection of isolated polymer molecules leads to an overall stretched exponential decay. Non-exponential relaxation is observed in all strongly interacting complex systems (structural glasses, spin glasses, etc ... ) where each elementary unit is in interaction with many other units.

Electroweak Phase Transition and the Early Universe, a NATO Advanced Re- search Workshop, was held March 23-25, 1994, at the Hotel Tivoli in Sintra, Portugal. The meeting was co-sponsored by three other Lisbon-based institutions: the Fundac;ao Gulbenkian, J. N.!. C. T. (Junta Nacional para Investigac;ao Cientifica e Tecnologica) and G. T. A. E. (Grupo Teorico de Alta Energias). The workshop brought together a large number of theoretical physicists who are actively researching topics relevant to the understanding of the standard model of electroweak interactions in the early universe. We were pleased and overwhelmed by the positive, and sometimes instan- taneous response that our enterprise raised right from its inception. The old town of Sintra provided a serene and pleasant environment for the par- ticipants. Some heated and controversial discussions on many unanswered questions in the standard model took place throughout the three days of the workshop. If one consensus emerged from the meeting, it was the imperative need for non-perturbative techniques for the understanding of the electroweak phase transition.

The three articles of the present volume clearly exhibit a wide scope of articles, which is the aim of this series. The article by Kahana and Baltz lies in the main flow of the large stream of work currently in progress with heavy-ion accelerators. A related article by Terry Fortune on "Multinuclear Transfer Reactions with Heavy Ions" is scheduled to appear in the next volume. The article by Whitehead, Watt, Cole, and Morrison pertains to the nuclear-shell model for which a number of articles have appeared in our series. Our very first volume had an article on how SU(3) techniques can, with great elegance, enable one to cope with the sizable number of states within a configuration. But the actual nuclear force is not exactly that yielded by the elegant techniques, and so interest continued in dealing with the large number of states by brute force. Then the Glasgow school of Whitehead et al. discovered that mathematical techniques existed for coping more simply with the lowest eigenvalues of large matrices. The present ar ticle aims generally to make accessible to nuclear physicists the methods developed at Glasgow. The final article by Baer, Crowe, and Truol on radiative pion capture describes a new field of importance because of the advent of the meson factories. More and more pions and muons will become standard tools in nuclear physics."

Justbefore the preliminary programof Orbis Scientiae 1998 went to press the news in physics was suddenly dominated by the discovery that neutrinos are, after all, massive particles. This was predicted by some physicists including Dr. Behram Kusunoglu, who had apaper published on this subject in 1976 in the Physical Review. Massive neutrinos do not necessarily simplify the physics of elementary particles but they do give elementary particle physics a new direction. If the dark matter content ofthe universe turns out to consist ofneutrinos, the fact that they are massive should make an impact on cosmology. Some of the papers in this volume have attempted to provide answers to these questions. We have a long way to go before we find the real reasons for nature's creation of neutrinos. Another neutrino-related event was the passing of their discoverer, Fredrick Reines: The trustees of the Global Foundation, members of the Orbis Scientiae 1998, dedicate this conference to Fredrick Reines of the University of California at Irvine. The late Professor Reines was a loyal and active member of these series of conferences on the frontiers of physics and cosmology since 1964. He also sewed as one of the trustees of the Global Foundation for the past three years. Professor Reines discovered the most elusive particle, the neutrino, in 1954. We are proud to say that we recognized the importance of this discovery by awarding him the J.

Nowadays the realm of intermediate energy as a bridge between nuclear and particle physics attracts considerable interest. This volume surveys recent developments in the theory of quark correlations in hadronic matter and also informs about experimental findings. The main themes are: dynamicalsymmetries of heavy quarks, diquarks, weak interactions, hadron spectroscopyand quark models, chiral invariant quark forces, quark confinement and quarkaspects of hadronic interactions.

This volume presents the proceedings of the Workshop on Momentum Distributions held on October 24 to 26, 1988 at Argonne National Laboratory. This workshop was motivated by the enormous progress within the past few years in both experimental and theoretical studies of momentum distributions, by the growing recognition of the importance of momentum distributions to the characterization of quantum many-body systems, and especially by the realization that momentum distribution studies have much in common across the entire range of modern physics. Accordingly, the workshop was unique in that it brought together researchers in nuclear physics, electronic systems, quantum fluids and solids, and particle physics to address the common elements of momentum distribution studies. The topics dis cussed in the workshop spanned more than ten orders of magnitude range in charac teristic energy scales. The workshop included an extraordinary variety of interactions from Coulombic to hard core repulsive, from non-relativistic to extreme relativistic."

This volume presents the contributions delivered at the "Josef-Loschmidt-Sympo sium," which took place in Vienna, June 25-27, 1995. The symposium was arranged to honor Josef Loschmidt one hundred years after his death (8 July 1895), to evaluate the sig nificance of his contributions to chemistry and physics from a modem point of view and to trace the development of scientific fields in which he had done pioneering work. Loschmidt is widely known for the first calculation of the size of molecules (1865/66), which also led to values for the number of molecules in unit gas volume and for the mass of molecules. With critical analyses of problems in statistical physics he made important contributions to the development of that field, "Loschmidt's paradoxon" continuing to be a point of departure for present day studies and discussions. For decades there was little awareness that Loschmidt was a pioneer in organic struc tural chemistry. Only in recent years has Loschmidt's first scientific publication "Chemis che Studien I", published in 1861, become more widely known and it is now recognized that with his ideas on the structure of organic molecules he was greatly ahead of the chemists of that time. The papers in these proceedings are arranged in three sections: l. Organic structural chemistry (Chapters 1-12). 2. Physics and physical chemistry (Chapters 13-26). 3. Loschmidt's biography, Loschmidt's world (Chapters 27-33).

Applying a unified quantum approach, contributors offer fresh insights into the theoretical developments in the excitation energy transfer processes in condensed matter. This comprehensive volume examines Frenkel and Wannier excitonic processes; rates of excitonic processes; theory of laser sputter and polymer ablation; and polarons, excitonic polarons and self-trapping.

Perhaps the most controversial aspeat of this volume is the number (V) assigned to the aonferenae in this series. Actually, the first aonferenae to be held under the title '~tomia Collisions in Solids" was held at Sussex University in England in 1969 and the seaond at Gausdal, Norway in 19?1, whiah would logically make the aonferenae held at Gatlinburg, Tennessee, U. S. A. in 19?3 the third (III). However, the appearance of the proceedings of the 19?1 Gausdal Conference (published by Gordon and Breaahj bore the number IV. The reasoning behind this was that, in. faat, two pre- vious aonferenaes had been largely dedicated to the same subjeat area. The first of these was at Aarhus, Denmark in 1965 and the seaond in 196? was held in Chalk River, Canada. Henae, the number V for the 19?3 meeting. Actually, the aonferenae aan easily be traaed baak to Paris, Franae in 196l when it went under the colorful title of '~e Bom- bardement Ionique. " In 1962 a small aonferenae was held at Oak Ridge, Tennessee, U. S. A. at whiah the discovery of channeling was first formally annunciated. This was followed by aonferenaes at Chalk River, Canada in 1963 and at Harwell, England in 1964. More- over, immediately following the Chalk River conference in 196? there was a aonferenae on higher energy collisions at Brookhaven, New York, U. S. A. Thus, strictly speaking, the Gatlinburg meeting is the tenth (X) in the series.

This volume contains the Proceedings of the Third International Conference on Navier-Stokes Equations and Related Nonlinear Problems. The conference was held in Funchal (Madeira, Portugal), on May 21-27, 1994. In addition to the editor, the organizers were Carlos Albuquerque (FC, University of Lisbon), Casimiro Silva (University of Madeira) and Juha Videman (1ST, Technical University of Lisbon). This meeting, following two other successful events of similar type held in Thurnau (Germany) in 1992 and in Cento (Italy) in 1993, brought together, to the majestically beautiful island of Madeira, more than 60 specialists from all around the world, of which about two thirds were invited lecturers. The main interest of the meeting was focused on the mathematical analysis of nonlinear phenomena in fluid mechanics. During the conference, we noticed that this area seems to provide, today more than ever, challenging and increasingly important problems motivating the research of both theoretical and numerical analysts. This volume collects 32 articles selected from the invited lectures and contributed papers given during the conference. The main topics covered include: Flows in Unbounded Domains; Flows in Bounded Domains; Compressible Fluids; Free Boundary Problems; Non-Newtonian Fluids; Related Problems and Numerical Approximations. The contributions present original results or new surveys on recent developments, giving directions for future research. I express my gratitude to all the authors and I am glad to recognize the scientific level and the actual interest of the articles.

The book addresses graduate students as well as scientists interested in applications of the standard model for strong and electroweak interactions to experimentally determinable quantities. Computer simulations and the relations between various approaches to quantum field theory, such as perturbative methods, lattice methods and effective theories, are also discussed.

From March 30th to April 3rd, 1992, a NATO Advanced Research workshop entitled "Time Dependent Quantum Molecular Dynamics: Theory and Experiment" was held at Snowbird, Utah. The organizing committee consisted of J. BROECKHOVE (Antwerp, Belgium), L. CEDERBAUM (Heidelberg, Germany), L. LATHOUWERS (Antwerp, Belgium), N. OHRN (Gainesville, Florida) and J. SIMONS (Salt Lake City, Utah). Fifty-two participants from eleven different countries attended the meeting at which thirty-three talks and one poster session were held. Twenty-eight participants submitted contributions to the proceedings of the meeting, which are reproduced in this volume. The workshop brought together experts in different areas 0 f molecular quantum dynamics, all adhering to the time dependent approach. The aim was to discuss and compare methods and applications. The ~amiliarityo~ the aUdience with the concepts o~ time dependent approaches greatly facilitated topical discussions and probing towards new applications. A broad area of subject matter was covered including time resolved laser chemistry, intramolecular dynamics, photodissociation dynamics, reactive and inelastic collisions as well as new time dependent methodologies. This diversity in applications is reflected in the contributions included in this volume .

This book had its origins in lectures presented at EPFL, Lausanne, during two separate visits (the most recent being to IRRMA). The author is most grateful to Professors A. Baldereschi, R. Car, and A. Quattropani for making these visits possible, and for the splendidly stimulating environment provided. Professors S. Baroni and R. Resta also influenced considerably the presentation of material by constructive help and comments. Most importantly, Chapters 4 and 5 were originally prepared for a review article by Professor G. Senatore, then at Pavia and now in Trieste, and myself for Reviews of Modem Physics (1994). In the 'course of this collaboration, he has taught me a great deal, especially about quantum Monte Carlo procedures, and Chapter 5 is based directly on this review article. Also in Chapter 4, my original draft on Gutzwiller's method has been transformed by his deeper understanding; again this is reflected directly in Chapter 4; especially in the earlier sections. In addition to the above background, it is relevant here to point out that, as a backcloth for the present, largely "state of the art," account, there are two highly relevant earlier books: The Many-body Problem in Quantum Mechanics with W.

Elastic and inelastic scattering in transmission electron microscopy (TEM) are important research subjects. For a long time, I have wished to systematically summarize various dynamic theories associated with quantitative electron micros copy and their applications in simulations of electron diffraction patterns and images. This wish now becomes reality. The aim of this book is to explore the physics in electron diffraction and imaging and related applications for materials characterizations. Particular emphasis is placed on diffraction and imaging of inelastically scattered electrons, which, I believe, have not been discussed exten sively in existing books. This book assumes that readers have some preknowledge of electron microscopy, electron diffraction, and quantum mechanics. I anticipate that this book will be a guide to approaching phenomena observed in electron microscopy from the prospects of diffraction physics. The SI units are employed throughout the book except for angstrom (A), which is used occasionally for convenience. To reduce the number of symbols used, the Fourier transform of a real-space function P'(r), for example, is denoted by the same symbol P'(u) in reciprocal space except that r is replaced by u. Upper and lower limits of an integral in the book are (-co, co) unless otherwise specified. The (-co, co) integral limits are usually omitted in a mathematical expression for simplification. I very much appreciate opportunity of working with Drs. J. M. Cowley and J. C. H. Spence (Arizona State University), J.

The NATO Advanced Study Institute (ASI) on "R@lativistic and Electron Correlation Effects in Molecules and Solids", co-sponsored by Simon Fraser University (SFU) and the Natural Sciences and Engineering Research Council of Canada (NSERC) was held Aug 10- 21, 1992 at the University of British Columbia (UBC), Vancouver, Canada. A total of 90 lecturers and students with backgrounds in Chemistry, Physics, Mathematics and various interdisciplinary subjects attended the ASI. In my proposal submitted to NATO for financial support for this ASI, I pointed out that a NATO ASI on the effects of relativity in many-electron systems was held ten years ago, [See G.L. Malli, (ed) Relativistic Effects in Atoms, Molecules and Solids, Plenum Press, Vol B87, New York, 1983]. Moreover, at a NATO Advanced Research Workshop (ARW) on advanced methods for molecular electronic structure "an assessment of state-of the-art of Electron Correlation ... " was carried out [see C.E. Dykstra, (ed), Advanced Theories and Computational Approaches to the Electronic Structure of Molecules, D. Reidel Publishin~ Company, Vol C133, Dordrecht, The Netherlands 1984]. However, during the last five years, it has become clear that the relativistic and electron correlation effects must be included in the theoretical treatment of many-electron molecules and solids of heavy elements (with Z > 70). Molecules and clusters containing heavy elements are of crucial importance in a number of areas of Chemistry and Physics such as nuclear fuels, catalysis, surface science, etc.

The theory of the inhomogeneous electron gas had its origin in the Thomas Fermi statistical theory, which is discussed in the first chapter of this book. This already leads to significant physical results for the binding energies of atomic ions, though because it leaves out shell structure the results of such a theory cannot reflect the richness of the Periodic Table. Therefore, for a long time, the earlier method proposed by Hartree, in which each electron is assigned its own personal wave function and energy, dominated atomic theory. The extension of the Hartree theory by Fock, to include exchange, had its parallel in the density description when Dirac showed how to incorporate exchange in the Thomas-Fermi theory. Considerably later, in 1951, Slater, in an important paper, showed how a result similar to but not identical with that of Dirac followed as a simplification of the Hartree-Fock method. It was Gombas and other workers who recognized that one could also incorporate electron correlation consistently into the Thomas-Fermi-Dirac theory by using uniform electron gas relations locally, and progress had been made along all these avenues by the 1950s."

The EPSRC (Engineering and Physical Science Research Committee of the U. K. ) suggested two Workshops (York University, 22-23 September, 1993 and 15-16 April, 1994) for possible development of polarized electron/photon physics as targeted areas of research. The remit of these meetings included identifying research groups and their activities in polarized electron/polarized photon physics, listing relevant existing facilities (particularly electron spin sources and polarimeters), possible joint projects between research groups in the U. K. , recognizing future needs of projects for research of the highest scientific merit and referring to international comparisons of these research activities. Although very diverse but interconnected, the areas of research presented at the Workshops embrace atomic, molecular, surface, and solid state physics. In more detail these areas covered: electron spin correlations and photon polarization correlations in atomic and molecular collisions and photoionization, electron spin effects in scanning tunneling microscopy, surface and interface magnetism from X-ray scattering and polarized Auger electrons (including analysis of domain structures in solids and surfaces), polarized electrons from multiphoton ionization, quasi-atomic effects in solid state physics, dichroism in molecular and surface processes, Faraday rotation and high-field magneto-optics and polarization effects in simultaneous higher order electron-photon excitations. It is obvious from the spectrum of research fields presented at the Workshops that physicists of primarily two communities, namely those studying electron and photon spin interactions with gaseous atomic and molecular targets and those using condensed matter targets for their studies, interacted very closely with each other.

In the slightly more than thirty years since its formulation, the Hubbard model has become a central component of modern many-body physics. It provides a paradigm for strongly correlated, interacting electronic systems and offers insights not only into the general underlying mathematical structure of many-body systems but also into the experimental behavior of many novel electronic materials. In condensed matter physics, the Hubbard model represents the simplest theoret ical framework for describing interacting electrons in a crystal lattice. Containing only two explicit parameters - the ratio ("Ujt") between the Coulomb repulsion and the kinetic energy of the electrons, and the filling (p) of the available electronic band - and one implicit parameter - the structure of the underlying lattice - it appears nonetheless capable of capturing behavior ranging from metallic to insulating and from magnetism to superconductivity. Introduced originally as a model of magnetism of transition met als, the Hubbard model has seen a spectacular recent renaissance in connection with possible applications to high-Tc superconductivity, for which particular emphasis has been placed on the phase diagram of the two-dimensional variant of the model. In mathematical physics, the Hubbard model has also had an essential role. The solution by Lieb and Wu of the one-dimensional Hubbard model by Bethe Ansatz provided the stimulus for a broad and continuing effort to study "solvable" many-body models. In higher dimensions, there have been important but isolated exact results (e. g., N agoaka's Theorem)."