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.

The symbiosis between particle physics and cosmology has virtually become a conjugal relationship. Hence the 9th biennial Course of the International School of Cosmic-Ray Astrophysics was designed to bridge these formerly dispa- rate disciplines. This NATO Advanced Study Institute (ASI) took place at the Ettore Majorana Centre in Erice, Italy, June 20-30, 1992. Seventy participants from 17 countries enjoyed the opportunities for lively interactions as much as they benefitted from the stimulating lectures. This volume is based on a selection of lectures and shorter talks presented at the sessions. Warm thanks are due to my co-director, Prof. J. P. Wefel and to co-editor Dr. Rein Silberberg for their co- operation. The support of NATO's Scientific Affairs Di- vision and of Dr. L. V. da Cunha, Director of its ASI Pro- gramme, was invaluable. We also acknowledge important con- tributions by the following: Prof. A. Zichichi, Director of the Majorana Centre and its dedicated staff; the Italian Ministry of Education; the Italian Ministry of Scientific Research; the Sicilian Regional Government; the National Science Foundation of the USA, the European Physical Soci- ety, and Mrs. Shirley Ratner of Bethesda, Maryland. The Scientific Advisory Committee consisted of Profs. P. V. Auger, G. P. S. Occhialini, B. Rossi, M. M. Shapiro, R. Silberberg, J. A. Simpson, J. A. Van Allen, J. P. Wefel, and A. Zichichi. All of the foregoing persons and agencies helped make this ASI a memorable experience for the parti- cipants.

The original plans for a meeting to celebrate the second centenary of the As tronomical Observatory of Palermo were for a celebration with a double character. The gathering was to have both a historical character, appropriate for a bicenten nial, and a technical character, to note and chronicle the new phase of the history of the Observatory, which has prospered in parallel with the development of this fairly recent topic in astronomical research, the physics of stellar and solar coronae. After the untimely death of the Observatory's Director, Giuseppe S. Vaiana (Pippo to his many friends), a number of colleagues and friends insisted that the celebration should nevertheless be held and should be dedicated to this farsighted scientist who stimulated the development of coronal physics from the early x-ray observations of the solar corona to the recognition of coronae as an observable feature of nearly all stars. This memorial dedication did not change the character of the meeting, which was held in Palermo from 22 to 26 June 1992; as his contributions are very alive in the papers presented at the meeting and collected here, Pippo Vaiana has certainly achieved his place in the history of Astronomy."

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."

Minor bodies in the Solar System, though representing only a small fraction of the mass in the Solar System, may well play a fundamental role in terrestrial evolution. This book contains investigations of the dynamics and physics of comets, asteroids and meteor streams, and the rather controversial topic of periodic phenomena in the Solar System as signified by geological records, together with several associated developments in celestial dynamics. All these problems are interwoven. This book makes a contribution towards unravelling the nature of the interactions between the Earth and its celestial environment.

This NATO Advanced Study Institute course provided an updated understanding, from a fundamental and deep point of view, of the progress and current problems in the early universe, cosmic microwave background radiation, large-scale struc ture, dark matter problem, and the interplay between them. Emphasis was placed on the mutual impact of fundamental physics and cosmology, both at the theo retical and experimental or observational levels, within a deep and well defined programme, and a global unifying view, which, in addition, provides of careful inter-disciplinarity. In addition, each course of this series introduced and promoted topics or sub jects which, although not of a purely astrophysical or cosmological nature, were of relevant physical interest for astrophysics and cosmology. Deep understanding, clarification, synthesis, and careful interdisciplinarity within a fundamental physics framework, were the main goals of the course. Lectures ranged from a motivation and pedagogical introduction for students and participants not directly working in the field to the latest developments and most recent results. All lectures were plenary, had the same duration, and were followed by a discus sion. The course brought together experimentalists and theoreticans physicists, astro physicists and astronomers from a wide variety of backgrounds, including young scientists at the post-doctoral level, senior scientists and advanced graduate stu dents as well.

The Galactic cosmic rays have far-reaching effects on the interstellar medium, and they are, in turn, profoundly affected by the particles and fields in space. Supernova remnants and their expanding shock fronts pervade the Galaxy, heating the interstellar medium, and accelerating the cosmic rays. The interplay among the cosmic rays, the interstellar medium in which they propagate, and supernovae has been investigated for decades; yet these studies have generated as many enigmas as they have resolved. These puzzles continue to challenge observers and theorists alike. th This volume is devoted to selected lectures presented in the 7 Course of the International School of Cosmic-Ray Astrophysics in Erice, Italy in July-August, 1990. Alltogether, some 400 participants have attended the biennial sessions of this School since its inception in 1978. As its name implies, the School deals with cosmic-ray phenomena viewed in the broader context of astrophysics. Students and Lecturers are attracted from many astrophysical disciplines. Like earlier courses in this series, the present one was organized under the aegis of the Ettore Majorana Centre as a NATO Advanced Study Institute. Given the diverse scientific backgrounds of the students, it was deemed useful to include lectures at the introductory level. Other lectures and contributed talks were at a more advanced level, featuring new developments. If this collection is useful pedagogically, and if it provides some stimulus and information for the mature research worker, then the editors will feel well rewarded.

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."

When I became President of International Astronomical Union Commission 44 for the triennial period 1985-1988, several members of the Organizing Committee and I agreed that it would be a good idea for our Commission to host a conference on observatories in space in view of their increasingly important role in astronomi cal research. IAU Colloquium Number 123 "Observatories in Earth Orbit and Beyond" is the first colloquium sponsored by IAU Com mission 44 on Astronomy from Space, although Commission 44 has co-sponsored numerous colloquia and symposia in the past. The past two decades have seen a flourishing of astronomical observatories in space. Over a dozen orbiting observatories have opened up a new window on the universe, providing hitherto una vailable data in the electromagnetic spectral range from gamma-ray, X-ray, ultraviolet to infrared and radio. This has clearly demon strated the crucial nature of astronomical observations from space. The invited talks of present colloquium consist primarily of reviews of currently operating observatories in space, future observatories that have been approved by sponsoring government or space agencies, the launch systems of U.S.A., E.S.A., U.S.S.R. and Japan, discussions of various orbits and sites (such as the Moon), and alternate approaches in designing space observatories. Several panel discus sions addressed those issues as well as the major unsolved problems of astronomy. Contributed poster papers included descriptions of space observatories that are in planning stage."

The morphological scheme devised by Hubble and followers to classify galaxies has proven over many decades to be quite effective in directing our quest for the fundamental pa rameters describing the extragalactic manifold. This statement is however far more true for spirals than for ellipticals. Echoing the concluding remarks in Scott Tremaine's sum mary talk at the Princeton meeting on Structure and Dynamics of Elliptical Galaxies, "the Hubble classification of spirals is useful because many properties of spirals (gas con tent, spiral arm morphology, bulge prominence, etc. ) all correlate with Hubble time. By contrast, almost nothing correlates with the elliptical Hubble sequence El to E7. " During the last few years much effort has been put into the search for a more meaningful classification of ellipticals than Hubble's. Concomitantly, forwarded by some provocative conjectures by R. Michard, the classical question of whether E galaxies form a physically homogeneous family has been brushed up once more. Results of these and other parallel studies look rather promising and point to suture part of the dichotomy between ellipticals and disk galaxies which had become popular in the early eighties, owing to dynamical arguments. At the same time it appears more and more clear that, besides the usual genetic varieties of galaxies, products of environmental evolution must also be contemplated in building our modern picture of the "reign of galaxies" . The above considerations prompted us to solicit Prof."

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."

The articles in this book cover a broad range of topics in the field of nuclear physics, including many articles on the subject of high spin physics. With an emphasis on the discussion and analysis of future developments within a number of significant areas, the book's attempt to address the status of research at the beginning of the next century is to be welcomed by researchers and students alike.

The Sixth Trieste Conference on Chemical Evolution for the first time has also been a Euroconference. This year we focused on "First Steps in the Origin of Life in the Universe". (Both this Centre and the ICGEB have been sponsors since we first started planning the series with Professors Abdus Salam and Cyril Ponnamperuma. ) The conference had the following 11 sponsors: The Abdus Salam International Centre for Theoretical Physics, The European Commission, The SETI Institute, Consiglio Nazionale delle Ricerche, Rome, Italy, The International Centre for Genetic Engineering and Biotechnology, Trieste, The European Space Agency (ESA), National Aeronautics and Space Administration (NASA) Universite Paris 12, The ICTP Public Information Office, La Fondazione Internazionale Trieste per il Progresso e la Liberta della Scienza, and II Laboratorio dell'Immaginario Scientifico. of our Over 90 participants allowed us to make a truly comprehensive review subject. In 82 presentations we had contributions from experts in questions related to the origin, evolution, distribution and destiny of life in the universe, topics that are known together as the science ofastrobiology. The publication ofthese proceedings was largely due to a generous grant form the Consiglio Nazionale delle Ricerche, Rome, Italy. The general topic of the conference concerned the origin, evolution, distribution and destiny of life in the Universe, a subject referred to as astrobiology and also as exobiology. In this report we prefer the synonym Astrobiology.

The nature of time has long puzzled physicists and philosophers. Time potentially has very fundamental yet unknown properties. In 1993 a new model of multi-dimensional time was found to relate closely to properties of the cosmological redshift. An international conference was subsequently convened in April 1996 to examine past, current and new concepts of time as they relate to physics and cosmology. These proceedings incorporate 34 reviews and contributed papers from the conference. The major reviews include observational properties of the redshift, alternative cosmologies, critical problems in cosmology, alternative viewpoints and problems in gravitation theory and particle physics, and new approaches to mathematical models of time. Professionals and students with an interest in cosmology and the structure of the universe will find that this book raises critical problems and explores challenging alternatives to classical viewpoints.

From August 21 through August 27, 1989 the Nato Advanced Research Workshop Probabilistic Methods in Quantum Field Theory and Quantum Gravity" was held at l'Institut d'Etudes Scientifiques, Cargese, France. This publication is the Proceedings of this workshop. The purpose of the workshop was to bring together a group of scientists who have been at the forefront of the development of probabilistic methods in Quantum Field Theory and Quantum Gravity. The original thought was to put emphasis on the introduction of stochastic processes in the understanding of Euclidean Quantum Field Theory, with also some discussion of recent progress in the field of stochastic numerical methods. During the final preparation of the meeting we broadened the scope to include all those Euclidean Quantum Field Theory descriptions that make direct reference to concepts from probability theory and statistical mechanics. Several of the main contributions centered around a more rigorous discussion of stochastic processes for the formulation of Euclidean Quantum Field Theory. These rather stringent mathematical approaches were contrasted with the more heuristic stochastic quantization scheme developed in 1981 by Parisi and Wu: Stochastic quan tization, its intrinsic BRST -structure and stochastic regularization appeared in many disguises and in connection with several different problems throughout the workshop.

The numerous applications of optimal control theory have given an incentive to the development of approximate techniques aimed at the construction of control laws and the optimization of dynamical systems. These constructive approaches rely on small parameter methods (averaging, regular and singular perturbations), which are well-known and have been proven to be efficient in nonlinear mechanics and optimal control theory (maximum principle, variational calculus and dynamic programming). An essential feature of the procedures for solving optimal control problems consists in the necessity for dealing with two-point boundary-value problems for nonlinear and, as a rule, nonsmooth multi-dimensional sets of differential equations. This circumstance complicates direct applications of the above-mentioned perturbation methods which have been developed mostly for investigating initial-value (Cauchy) problems. There is now a need for a systematic presentation of constructive analytical per turbation methods relevant to optimal control problems for nonlinear systems. The purpose of this book is to meet this need in the English language scientific literature and to present consistently small parameter techniques relating to the constructive investigation of some classes of optimal control problems which often arise in prac tice. This book is based on a revised and modified version of the monograph: L. D. Akulenko "Asymptotic methods in optimal control." Moscow: Nauka, 366 p. (in Russian)."

A wealth of new experimental and theoretical results has been obtained in solar physics since the first edition of this textbook appeared in 1989. Thus all nine chapters have been thoroughly revised, and about 100 pages and many new illustrations have been added to the text. The additions include element diffusion in the solar interior, the recent neutrino experiments, methods of image restoration, observational devices used for spectroscopy and polarimetry, and new developments in helioseismology and numerical simulation. The book takes particular advantage of the results of several recent space missions, which lead to substantial progress in our understanding of the Sun, from the deep interior to the corona and solar wind.

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.

The twenty-second Coral Gables conference "UNIFIED SYMMETRY: In the Small and In the Large" continued with the efforts to unify the small and the large. The information gathered with the Huble telescope has in part, in the absence of the SCC , provided a basis for the physicists to unify cosmology and elementary particle physics. The congressional cancellation of the biggest experimental project on the frontiers of physics should not be regarded as an insurmountable obstacle to progress in theoretical physics. The physicists' rise to prominence was mostly reached through their creation of the nuclear era. The post cold war era has somewhat reduced the political, military, and, in part, the social role of the physicist. Some in the administration and the Congress would like physicists to focus on the directly utilitarian aspects of science. Thus, some people do not realize that this regimentation of science would inhibit the creativity. The contributions of solid state physics research to the advancement of technology is the result of physics freely pursued independently of its applications. Modern Physics beginning with Newton's theory of gravity has enabled us to create the space age, to contribute to various technologies, and to impact on our technological modus vivendi.

Outstanding progress in near-infrared detection technology and in real-time image processing has led astronomers to start undertaking all-sky surveys in the 1--2 mum range (project DENIS in Europe and 2MASS in the U.S.A.), surveys which will have a considerable impact in various areas of astronomy. This book gathers the contributions of more than 80 specialists involved in fields of interest as different as low mass stars, late stages of stellar evolution, star formation, stellar populations of the Galaxy and the Magellanic Clouds, the local structure of the Universe, and observational cosmology. It describes the impact on these fields of the exhaustive data bases and catalogs of stars and galaxies that these surveys will provide. The considerable interest of these documents for the future of infrared space and ground-based projects and the complementarity with other currently ongoing or planned surveys in other spectral ranges are emphasized.

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.

Solid particles are followed from their creation through their evolution in the Galaxy to their participation in the formation of solar systems like our own, these being now clearly deduced from observations by the Hubble Space Telescope as well as by IR and visual observations of protostellar disks, like that of the famous Beta Pictoris object. The most recent observational, laboratory and theoretical methods are examined in detail. In our own solar system, studies of meteorites, comets and comet dust reveal many features that follow directly from the interstellar dust from which they formed. The properties of interstellar dust provide possible keys to its origin in comets and asteroids and its ultimate origin in the early solar system. But this is a continuing story: what happens to the solid particles in space after they emerge from stellar sources has important scientific consequences since it ultimately bears on our own origins - the origins of solar systems and, especially, of our own earth and life in the universe.

This book reproduces the proceedings of the last of a series of EUROCONFERENCE dedicated to the on-going near-infrared sky surveys DENIS and 2MASS. It presents the current status of both projects and some of the most outstanding results they have recently achieved in various areas of galactic and extragalactic astronomy. A first analysis of the relevant results of the space mission MSX is also presented. The book contains substantial articles by researchers directly involved in the survey data processing and interpretation that thoroughly describe the astrophysical context in which deep and homogeneous near-infrared surveys will eventually bring about significant breakthrough. They deal with the determination of basic parameters of the galactic structure, the stellar content of the bulge, the construction of unbiased and statistically significant samples of isolated very low mass stars and brown dwarfs, the improvement of the low-end of the stellar luminosity and mass functions, the complete census of young stellar objects in nearby giant molecular clouds, the accurate determination of the luminosity function of late-type giants in the Magellanic Clouds and the structure of the local universe. The analysis of a very small subsample of the full expected set of data promises an extraordinary harvest of discoveries in the next few years especially when these data are merged with the results of major related space missions such as Hipparcos and ISO. Audience: This book is of general interest for graduate students in astronomy and professional astronomers involved in most areas of observational astronomy.

The Twenty-third Coral Gables conference on Unified Symmetry in the Small and in the Large was convened February 2-5, 1995. The shift of the traditional conference time from the last part of January was caused by the 1995 Superbowl's choice of our preferred date for their game. The conference was dedicated to reminiscences of Julian Schwinger. The death of Eugene P. Wigner in the early part of January 1995 was observed with a deep sorrow during the conference. At about that time the news of Asim Barut's death made 1995 an inauspicious year for physicists. In the meantime physics at the frontiers marched on as it did before. There were no path-breaking discoveries, but hope and persistence were still there. In 1964 (the first Coral Gables conference) if we had asked a physicist to give us a sincere opinion on what is "hot" in physics we would have expected him or her to point out the narrow area of their own research. The answer to this question in 1995 is still the same as it would have been in 1964. The mind set is a human quality and even in physics the physicist can respond like a religious believer.

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