In the 18th century, purely scientific interests as well as the practical necessities of navigation motivated the development of new theories and techniques to accurately describe celestial and lunar motion. "Between Theory and Observations" presents a detailed and accurate account, not to be found elsewhere in the literature, of Tobias Mayer's important contributions to the study of lunar motion-including the creation of his famous set of lunar tables, which were the most accurate of their time.

Optics is reborn. There is fresh new vitality in applying old techniques to new prob lems and fully exploring novel phenomena. Lasers, holography, stellar navigation, nonlinear phenomena, and remote sensing are subjects of the seventies, and their further development will increase our understanding of nature and the development of technology. This Series is devoted to provid ing ideas and data to nourish the growth of these scientific and engineering en deavors' for we feel strongly that science and engineering flourish best when they grow together. Some of the volumes in the Series will be devoted to the optical properties of materials, theories of the detailed mechanisms of absorption, reflection, and nonlinea r phenomena, and electro-optical coefficients. The understanding of such things leads to further engineering applications. Companions to such theoretical books will be compendia of property data; the triad is completed by monographs on the use of the materials in op tical and electro-optical systems. Laser materials, lasers, and laser sys tems form one of the groups which will comprise the full set of ready-reference material for the entire field. The Series will be intentionally international, including a fair sampling of Russian work. There are important benefits to be obtained in the alternate approaches often taken by our Soviet and other foreign colleagues (just as they can gain from studying ours)."

The Cargese Workshop Random Surfaces and Quantum Gravity was held from May 27 to June 2, 1990. Little was known about string theory in the non-perturbative regime before Oetober 1989 when non-perturbative equations for the string partition functions were found by using methods based on the random triangulations of surfaees. This set of methods pro vides a deseription of non-eritical string theory or equivalently of the coupling of matter fields to quantum gravity in two dimensions. The Cargese meeting was very successful in that it provided the first opportunity to gather most of the active workers in the field for a fuH week of lectures and extensive informal discussions about these exeiting new developments. The main results were reviewed, recent advances were explained, new results and conjectures (which appear for the first time in these proceedings) were presented and discussed. Among the most important topics discussed at the workshop were: The relation of KdV theory to loop equations and the Virasoro algebra, new results in Liouville field theory, effective (1 + 1) dimensional theory for 2 - D quantum gravity coupled to c = 1 matter and its fermionization, proposal for a new geometrical interpretation of the string equation and possible definition of quantum Riemann surfaces, discussion of the string equation for the multi-matrix models, links with topological field theories of gravity, issues in using target space supersymmetry to define good theories, definition of the partition function via analytic continuation, new models of random surfaces

Modern astronomical research faces a vast range of statistical issues which have spawned a revival in methodological activity among astronomers. The Statistical Challenges in Modern Astronomy II conference brought astronomers and statisticians together to discuss methodological issues of common interest. Time series analysis, image analysis, Bayesian methods, Poisson processes, nonlinear regression, maximum likelihood, multivariate classification, and wavelet and multiscale analyses were all important themes. Many problems were introduced at the conference in the context of large-scale astronomical projects including LIGO, AXAF, XTE, Hipparcos, and digitised sky surveys. As such, this volume will be of interest to researchers and advanced students in both fields - astronomers seeking exposure to recent developments in statistics, and statisticians interested in confronting new problems.

The launch in October 1990 of the joint ESA-NASA Ulysses mission marked the start of a new era in the study of the heliosphere. For the fIrst time, in-situ observations are being made covering the full range of heliographic latitudes. Following the successful gravity-assist manoeuvre at Jupiter in February 1992, Ulysses left the ecliptic plane in a southerly direction and headed back toward the Sun, passing over the southern solar pole in mid-1994. To mark these unique events, the 28th ESLAB Symposium, held in Friedrichs hafen, Germany, on 19-21 April 1994, was devoted to "The High Latitude Helio sphere." Following on from the highly successful 19th ESLAB Symposium "The Sun and the Heliosphere in Three Dimensions" (Les Diablerets, 1985), the purpose of the meeting was to review out-of-ecliptic results from the Ulysses mission obtained to date, and to provide a focus for the fIrst polar pass. Relevant results from other space missions, as well as ground-based and theoretical studies, were also included. Attended by 130 scientists, the main themes of the Symposium were The Sun and Corona, Large-Scale Heliospheric Structure, Energetic Particles in the Heliosphere, Cosmic Rays in the Heliosphere, and Interstellar Gas and Cosmic Dust. The scientifIc programme consisted of a number of Topical Review papers introducing various as pects of these themes, supplemented by a large number of contributed papers (72 in to tal) presented either orally or as posters. Undoubtedly, the excellent poster sessions formed one of the highlights of the meeting."

An almost complete collection of the papers given at the International Workshop on Imaging in High Energy Astronomy (Anacapri, Italy, 1994). These proceedings, which concentrate on imaging above 10 keV, represent the state of the art in the field, resulting from the success of many missions (I.C. Granat and CGRO) carrying detectors for high energy astronomy with imaging capabilities. The main topics of the book are Bragg concentrators, coded mask-modulation collimators, double Compton telescopes, the occultation method, tracking chambers, and new experimental techniques. The book also contains some papers dealing with image reconstruction and processing, with an emphasis on the above techniques.

Our Galactic center's proximity allows astronomers to study physical pro cesses within galactic nuclei at a level of detail that will never be possible in the more distant, but usually also more spectacular, extragalactic systems. Recent advances in instrumentation from the radio, through the submillime ter and infrared wavebands, and out to the X- and "'(-ray bands now allow observations of the Galactic Center over thirteen orders of magnitude in wave length. Our knowledge about the central few hundred parsecs of our Galaxy has consequently increased vastly over the past decade. The same new instru ments provide high resolution, high quality measurements of nearby ''normal'' galactic nuclei; that is, nuclei whose modest energy output is comparable to that of our own (and most other) galaxies. Theorists, spurred in part by the new observations, have been able to refine models of the energetics, dynam ics, and evolution of the gas and stellar systems deep within galactic nuclei."

Modern observations, including recent ones with the Hubble Space Telescope, have revealed that the Universe is replete with plasma outflows from all kinds of objects, ranging from stars in all their variety to galaxies. In this masterly survey of plasma astrophysics, written by leading practitioners, the first 15 articles in Part I deal with the use of the MHD approach in several key problems of solar plasma, such as magnetoconvection and magnetic field generation, sunspots and coronal loops, magnetic nonequilibrium and coronal heating, coronal mass ejections, the acceleration of the solar wind, and stellar winds across the Main Sequence. The following 16 articles of Part II deal with the use of the same MHD approach in several central and puzzling aspects of more distant astrophysical plasmas, such as the dynamics of the interstellar medium, collimated outflows from young stellar objects and accretion disks, molecular outflows and jets associated with enigmatic binaries and symbiotic stars, relativistic flows associated with superluminal microquasars in our own galaxy, astrophysical jets from nearby galaxies, or remote active galactic nuclei and quasars, probably fuelled by supermassive black holes. The emphasis throughout is on the striking underlying similarities in the physics of all these problems. Audience: Indispensable for solar physicists and astrophysics alike. An ideal textbook for graduate students in physics and astrophysics.

This volume is based on the proceedings of the "NATO Advanced study Institute on Mineral Processing Design" held in Bursa-Turkey on August 24-31, 1984. The institute was organized by Professor B. Yarar of the Colorado School of Mines, Golden, Colorado, 80401, USA, Professor G. Ozbayoghu and Professor Z. M. Dogan of METU-Ankara, Turkey, who was the director. The purpose of the institute was to provide an international forum on the subject and update the information available. Participants were from Turkey, England, Greece, Spain, Portugal, Belgium, Canada, and the USA. Besides authors contributing to this volume, presentations were also made by Drs. Yarar, Raghavan, Schurger, and Mr. Kelland. Many assistants and colleagues helped. They are gratefully acknowledged. Acknowledgment is also owed to Drs. Ek, de Kuyper, and Tolun. Dr. Gfilhan Ozbayoglu, and Mr. S. Ozbayoglu were particularly helpful in the overall organization and hosting of many international guests. We owe them special thanks. NATO, Scientific Affairs Division, is gratefully acknowledged for the grant which made this activity possible. Z. M. Dogan B. Yarar 2 APPLIED MINERALOGY IN ORE DRESSING William Petruk CANMET, 555 Booth Street, Ottawa, Ontario, KIA OGI ABSTRACT Mineralogy applied to ore dressing is a reliable guide for designing and operating an efficient concentrator. A procedure for conductiqg mineralogical studies in conjunction with ore dressing was, therefore, developed. The procedure includes characterizing the ore and analysing the mill products.

This book contains the lectures presented at the Summer Advanced Study School, 'Magnetospheric Particles and Fields' which was held at Graz, Austria during the period August 4-15, 1975. One hundred and one persons from fifteen different countries attended the Schoo . The authors and publisher have made a special effort for rapid publication of an up-to date status of particles, fields, and processes in planetary magnetospheres. Special thanks are due to the lecturers for their diligent preparation and excellent presentations. The in dividuallectures and the published papers were deliberately limited; the authors' cooper ation in conforming to these specifications is greatly appreciated. Many thanks are due to Drs C. D. Anger, Gerhard Haerendel, George P. Haskell, Carl McIlwain, Vytenis Vasy liunas, Martin Walt, and James Warwick who served as session chairmen during the School and contributed greatly to its success by skillfully directing the discussion period in a stimulating manner after each lecture. Many persons contributed to the success of the School. Drs C. D. Anger, Carl-Gunne Falthammar, Gerhard Haerendel, George P. Haskell, Carl McIlwain, David Nunn, Willi Riedler, Finn Scentsraas, Vytenis M. Vasyliunas, Martin Walt, and James Warwick were especially helpful in preparing the technical program. Dr Willi Riedler assisted in ar ranging for the facilities in Graz. Drs Gerhard Kremser and Martin Friedrich were most helpful with many aspects of the local arrangements in Graz. The assistant editor, Mrs Diana R. McCormac, checked the manuscripts and proofs, and worked hard to achieve a uniform style in this book."

Photobiology - the science of light and life - begins with basic principles and the physics of light and continues with general photobiological research methods, such as generation of light, measurement of light, and action spectroscopy. In an interdisciplinary way, it then treats how organisms tune their pigments and structures to the wavelength components of light, and how light is registered by organisms. Then follow various examples of photobiological phenomena: the design of the compound eye in relation to the properties of light, phototoxicity, photobiology of the human skin and of vitamin D, photomorphogenesis, photoperiodism, the setting of the biological clock by light, and bioluminescence. A final chapter is devoted to teaching experiments and demonstrations in photobiology.
This book encompasses topics from a diverse array of traditional disciplines: physics, biochemistry, medicine, zoology, botany, microbiology, etc., and makes different aspects of photobiology accessible to experts in all these areas as well as to the novice. It is intended primarily for graduate students and for researchers who wish to look outside their speciality, but can also act as a source of information for undergraduate students.

The European Workshop on White Dwarfs was initiated by Prof. V. Weidemann, with the first meeting held in Kiel (FRG) in 1974. Since then a similar workshop has been held almost every two years: Frascati (1976), Tel Aviv (1978), Paris (1981), Kiel (1984), Frascati (1986) and Toulouse (1990). Two major IAU colloquia have also been devoted to the study of white dwarfs (No. 53, Rochester NY, 1979; No. 114, Hanover, NH, 1988). Our most recent meeting, the 8th Workshop, marks a number of important advances in both observational and theoretical studies of white dwarfs. This coincides with a significant expansion in the size of the community active in the field, as was clear from an increase in the number of participants between this workshop (77) and that in Toulouse (46), just two years ago. Key parts of any workshop are the discussion sessions following the pa pers. However, these are difficult to record and, very often, the 'live' flavour of the debates is lost. During this workshop we carried out an experiment, recording the discussion sessions on video tape and then transcribing these later for the proceedings. Although the recordings were made in non-studio conditions with regard to lighting and noise, only a very small part was unin telligible. All participants were given an opportunity to check their questions and answers for scientific accuracy and to correct any errors arising in the transcription process."

In many areas of physics, such as astrophysics, solid-state physics, nuclear physics and particle physics, a major outstanding problem is a better understanding of corre lation phenomena. While in most cases the average properties of a system are rather well understood, the correlations and the resulting clustering are poorly understood. They are reflections of the force mediating the interaction among the constituents and play essential roles in determining the structure of a physical system. At the largest scales, in astrophysics, it has recently been realized that there are huge voids in space and almost all matter is concentrated on filaments, raising interesting questions concerning the origin of this clustering of matter. In nuclear physics corre lation phenomena are important in all its subfields. It has been realized that so-called fluctuations in the one-particle density, which are a manifestation of nucleon-nucleon correlations, are crucial. These are important for an understanding of heavy-ion reac tions. This is the subject of modern quantum transport theories. Correlations are also crucial in the description of the high momentum components as observed in quasi-elastic knock-out reactions."

The 25'" Coral Gables Conference was the culmination of the series that was begun in 1964. The conferences evolved under the titles that in~lude: Symmetry Principles at High Energy; Fundamental Interactions; Orbis Scientiae; and, occasionally, Unified Symmetry in the Small and in the Large. There was a pause after the 2()1h meeting in 1983 which was dedicated to P. A. M. Dirac. The conferences were resumed in 1993. Some of the reminiscences involved the absence of great minds who attended these meetings in the past and who were no longer with us. The list includes, just to name a few: Julian Schwinger, Robert Oppenheimer, Lars Onsager, Robert Hofstater, Abdus Salam, Richard Feynman, Stanislov Ulam, P. A. M. Dirac, Lord C. P. Snow, Eugene P. Wigner, Vladimir K. Zworykin, and Dixie Lee Ray. Most of these people were among the architects of modern physics and had participated in many of the early Coral Gables Conferences. We miss them. These conferences have contributed to the progress in high energy physics and cosmology. This year, again, papers were presented on familiar topics, such as neutrino masses, age and total mass of the universe, on the nature of dark matter, and on supersymmetry. The latter has now become a perennial issue. Like the weather, we all talk about it, but, so far cannot do anything to affect it. Another favorite subject was so-called monopoles, which theoretically participate in phenomena like condensation, confinement of electric charge, confinement of monopoles themselves, etc.

I have been asked by Professor Kikuchi to write a foreword for this interesting book on Dusty Plasmas and other electrical phenomena. This was a somewhat daunting task due to the wide range of topics covered. In what follows I have attempted to summarize most of these topics; for this purpose I have divided them into four groups, namely (a) Dusty Plasmas, (b) The Electrical Environment, (c) Lightning and (d) The Noise Environment. I hope that I have succeeded. in indicating that each section contains much that is of great interest. It is perhaps unnecessary for me to point out that the book contains subjects which are at an exciting and important stage in their development. (a) Dusty Plasmas The subject of dusty plasmas is one of great interest. Dust particles in interplanetary space, within comets, in inter-stellar space and at ever greater distances will in general be charged. The plasma environment will ensure this, bombarding electrons will charge up the particle until it assumes a "floating potential," although time variation can occur. Ultra violet radiation can cause photoemission and in certain cases field emission is a possibility. The motion of the particles will be determined by electric and magnetic fields together with gravity. If the density of charged grains becomes sufficiently high the grains will interact with each other and collective behaviour will ensue. This newly evolving subject entails the study of all kinds of plasma waves.

Modem dynamics is increasingly participating in the solution of problems raised by as tronomical observations. This new relationship is being fostered on one side by the im provements in the observations, which in recent years contributed several discoveries of new systems, such as the objects in the Kuiper belt, the pulsar and star companions, to speak only of the most striking ones, and, on the other hand, by the progresses in modem dynamics. The progresses in modem dynamics are due to two factors: the dissemination of fast computers, allowing the numerical studies of very complex systems by a large number of scientists, and the improvement in our understanding of the complex behaviour of Hamiltonian systems. KAM and Nekhorochev theories have shed a light on the subtle and surprizing interplays between regular and chaotic motions; numerical experiments and analytical approximations have shown how these peculiarities are indeed present in astronomically important systems and are instrumental in understanding their formation and evolution.

Interstellar dust, meteorites, interplanetary dust particles (IDP's), the zodiacal light, comets, comet dust. Where do they come from, what are they made of, how do they evolve, and finally, are there connections between them? These are the questions discussed in this volume by some of the world's outstanding experts in their respective fields. The techniques used for studying the `small' solid objects of space are thoroughly discussed. Some of the methods involve a synthetic approach using the laboratory to create analog environments and materials which are believed to resemble those in space. Others use direct laboratory methods with state-of-the-art analytical tools to study the material of the objects themselves - meteorites, IDP'S. And others apply the latest in astronomical facilities to provide quantitative data on the material properties of the solids which can only be deduced from remote observations, These are compared with the laboratory results. In one instance there was a possibility to study a solar system body in situ and that was the case of comet Halley and some of the results of these studies obtained from space `laboratories' launched to meet it are discussed here. Finally, there are theoretical papers which are aimed at bridging the results of observational and laboratory methods. This book is recommended to senior scientists as well as graduate students who wish to pursue research in interstellar and solar system astronomy and their connections.

In May 1998 a hundred renowned scientists from 20 different countries met at the Max-Planck-Institut fur Aeronomie to communicate their latest results and ideas in astrophysical and space plasma, as a follow-up to previous similar meetings which were held in Varenna, Abastumai, Potsdam, Toki and Guaruja. The main papers emerging from this meeting are collected in this volume. They deal with fundamental plasma phenomena, particle and radiation processes in astrophysics and space physics as the origin of magnetic activity, the basic mechanisms of particle acceleration and plasma heating common to plasma in galaxies and at the sun as well as in planetary magnetospheres. New observational results from YOHKOH, SOHO and other missions are presented. Using these, the basic physical processes leading to coronal heating and solar/stellar wind acceleration are discussed. Other topics are the microphysics of shock waves and transport phenomena in collisionless plasmas and the physics of thin plasma boundaries. The volume also treats the ionic composition of plasma and dust in the Universe and their observability in the solar system. A CD-ROM is attached which adds a valuable multimedia component, illuminating results of observations, theory and simulations. Everyone interested in astrophysical plasmas, its radiation and charged particle aspects, and advanced or even beginning students will find references to nearly all modern aspects of plasma astrophysics and space physics as well as an overview of current research results.

IAU Transactions are published as a volume corresponding to each General Assembly. Volume A is produced prior to the Assembly and contains Reports on Astronomy, prepared by each Commission President. The intention is to summarize the astronomical results that have affected the work of the Commission since the production of the previous Reports up to a time which is about one year prior to the General Assembly. Volume B is produced after the Assembly and contains accounts of Commission Meetings which were held, together with other material. The reports included in the present volume range from outline summaries to lengthy compilations and references. Most reports are in English.

This second volume of Reviews in Modern Astronomy continues the new series of publications of the Astronomische Gesellschaft (AG). In order to bring the scientific events of the meetings of the society to the attention of the worldwide astronomical community, it was decided to devote a new annual publication, Reviews in Modern Astronomy, exclusively to the invited reviews, the Karl Schwarzschild lectures, and the highlight contributions from leading scientists reporting on recent progress and scientific achievements at their institutes. Volume 2 comprises the contributions presented during the spring meet- ing of the AG at Friedrichshafen in April 1989, which was dedicated to the topic "Astrophysics with Modern Technology - Space-based and Ground-based Systems", as well as those delivered at the fall meeting at Graz, Austria in September 1989. The Karl Schwarzschild lectures constitute a special series by outstanding scientists honoured with the Karl Schwarzschild medal of the Astronomische Gesellschaft. Between 1959 and 1987 the following scientists presented Karl Schwarzschild lectures at meetings of the Astronomische Gesellschaft: Martin Schwarzschild (1959) George Field (1978) Charles Fehrenbach (1963) Ludwig Biermann (1980) Maarten Schmidt (1968) Bohdan Paczynski (1981) Bengt Stromgren (1969) Jean Delhaye (1982) Antony Hewish (1971) Donald Lynden-Bell (1983) Jan H. Oort (1972) Daniel M. Popper (1984) Corne lis de Jager (1974) Subrahmanyan Chandrasekhar (1986) Lyman Spitzer Jr.

This book includes the proceedings of the Workshop held in Madrid, April 1999 to celebrate 2 years of successful operation of the first Spanish small scientific satellite in orbit. It contains discussions about the overall philosophy of small mission programs, the design of the satellite and its payload as well as the most relevant scientific outcome of the mission. Also included are additional contributions to the workshop, which are of importance to Minisat 01 in order to put its results within context. Finally, the future of small missions for space sciences is reviewed together with the main technological challenges for new studies. Out of the technological and scientific results of Minisat 01, the measurement of the EUV airglow spectrum and the flux of some stars in the same range can be highlighted together with the dismiss of the massive neutrino decay theory. The high-energy experiment analyzed the characterization of the radiation environment in LEO and the behaviour of different kind of detectors, as well as the use of coded masks for imaging and the measurement of some specific sources. The book's level is intended for specialists in EUV and Hard X-Ray astrophysicists as well as for engineers and technicians involved in space science experiments and missions.

This volume consists of invited lectures and seminars presented at the NATO Advanced Study Institute "The Gamma Ray Sky with COMPTON GRO and SIGMA," which was held at the Centre de Physique Theorique of Les Houches (France) in January / February 1994. The school has been planned by a Scientific Organizing Committee. It was organized with the aim of providing students and young researchers with an up-to-date account of the high-energy phenomena in the vicinity of compact objets and the diffuse gamma-ray backgrounds after the early results from the gamma-ray telescope SIGMA and the four instruments onboard COMPTON GRO (Gamma Ray Observatory): BATSE (Burst and Transient Source Experiment), COMPTEL(Compto'l Telescope), EGRET (Energetic Gamma Ray Experiment Telescope) and OS SE(Oriented Scintillation Spectrometer Experiment) . It was attended by more than sixty researchers from many countries. The lectures and seminars represent a complete coverage of our present knowledge and understanding of: Gamma-ray backgrounds, Gamma-ray Burts, Active Galactic Nuclei, Galactic Compact Objects, Gamma-ray Spectroscopy, Instrumentation and observation techniques, etc ... Most of these lectures are reproduced in this volume. Unfortunately, a few lecturers have chosen not to submit their manuscript.

Our conference - opening today - has two aims in view: first, to commemorate some milestones in the development of the studies of close binary systems whose anniversaries fall in these years, as well as to take stock of our present knowledge accumulated through out preceding decades, in order to consider where do we go from here. This summer, 310 years will have elapsed since the first ec lipsing binary - Algol - was discovered in Bologna by Geminiano Montanari (1633-1687) to be a variable star; and 198 years have gone by since John Goodricke of York (1764-1786) established the fact that Algol's light changes were periodic. Moreover, it is al most exactly (to a month) now 100 years since Edward Charles Pickering (1846-1919) of Harvard Observatory in the United States took the first steps towards the development of systematic methods of analysis of the light changes of Algol and related systems - a topic which will constitute the major part of the programme of our present conference. The three dates recalled above illustrate that the discoverers of such celestial objects and observers of their light changes have been systematically ahead of the theoreticians endea vouring to understand the significance of the observed data by de cades and centuries in the past - a fact which, incidentally, con tinues to hold good (albeit with a diminishing lead-time) up to the present.

The International Scientific Spring Meeting of the Astronomische Ge sellschaft (AG) held at Bamberg in April 1991 was devoted to "Vari abilities in Stars and Galaxies." Time-dependent phenomena are observed in a wide range of as tronomical objects. They are caused by different physical mechanisms (for example by pulsation, by accretion, or by dramatic eruptive events in connection with mass outflow) producing observable intensity vari ations through all wavelengths. Many of the papers in this volume are concerned with galactic stars showing such behaviour (for ex ample cataclysmic variables, symbiotic stars, luminous blue variables (LBVs) and novae). Intrinsic variations of the, magnetic field struc ture on observable time scales are, for instance, a peculiarity of cool, solar-like stars and represent a useful tool to study differential rotation and cycles of activity. Recent results on the investigation of gas motions in the inner regions of the Milky Way system, a study of the bipolar galaxy M 82, observations of variable extragalactic radio sources, the variability of emission lines in active galactic nuclei (AGN) as well as continuum variations of quasars and AGN are discussed by several authors. The yearbook series Reviews in Modern Astronomy of the AG to bring the scientific events of the was established in 1988 in order meetings of the society to the attention of the worldwide astronomical community."

A clear and accessible introduction to quantum mechanical methods used to calculate properties of atoms exposed to strong magnetic fields in both laboratory and stellar environments, with the emphasis on hydrogen and helium and their isoelectronic sequences. The results of the detailed calculations are listed in tables, making it a useful handbook for astrophysicists and atomic physicists alike.