Centre de Physique des Houches – serie

Starbursts are regions of unusually rapid star formation, often located in the central parts of galaxies. They differ from more normal regions of star formation in terms of the throughput of mass and the rapidity with which the gas is consumed. In the last twenty years, extensive observational data at most wavelengths have become available on starbursts, but many important issues remain to be addressed, observationally as well as theoretically. How are strong episodes of star formation triggered? What is the quantity of gas converted into stars during bursts? What is the initial mass function of stars in these events? How does the feedback from stars influence the interstellar medium and self-regulate star formation? What is the subsequent chemical and photometric evolution? How do starbursts rule the formation and evolution of galaxies? In recent years, many observational data at different wavelengths (optical, radio, infrared, X-ray) have become available. However, these observations are still fragmentary in the sense that different classes of objects have been observed in different ways, and the coverage is not consistently deep or complete. As a consequence, an overall observational picture of starburst galaxies is missing, and theoretical understanding and modelling have remained highly tentative. The purpose of the school Starbursts: Triggers, Nature, and Evolution was to gather theorists and observers with complementary approaches to the starburst phenomenon, in order to summarize the state-of-the-art of the observations and models, emphasizing the consistency of the various viewpoints.

Branching is probably the most common mode of growth in Nature. From plants to river networks, from lung and kidney to snow-flakes or lightning sparks, branches grow and blossom everywhere, in every realm of Nature. When Galileo Galilei stated that the geometry ofNature was written in terms ofplanes, cones and spheres, he missed one essential pattern of Nature: the tree. However, the tree has been recognized as a "scientific" objet very early, ever since the classical times. Pliny, Strabo or Theophrastus were weIl aware ofthe existence of"dendrites", i. e. , stones in the shape of plants or corals, although the existence of such stones was a puzzle to them. In his book Prodromus Cristallographiae, in which the very word cristallography appears in print for the first time (1711), Mauricius CapeIler, a Swiss naturalist, shows in between facetted crystals, several examples of dendritic crystals. He seemed already to believe in the existence of a general class of branching structures (arbusculatum in modum) in Nature. In the same spirit, his friend Jean-Jacques Scheuchzer had demonstrated experimentally that viscous fingering could generate geological dendrites (1699).At the time of Renaissance, Leornardo da Vinci was quite interested in the resemblance between trees and vessels (1508), and later, Nicola Steno did not hesitate in considering branched deposits of silver found in mines as a close relative of snow.

The discovery of bright visible light emission from porous silicon has opened the door to various nanometer-sized silicon structures where the confinement of carriers gives rise to interesting physical properties. While the high efficiency of the light emission in the visible range is the common and most prominent feature, their structures display properties similar to other highly divided materials (even non-semiconductors), which justifies a multidisciplinary approach. The book addresses graduate students, physicists and engineers who want to learn about optoelectronic devices based on porous silicon and on the electrochemistry of semiconductors, basic techniques, and the theoretical background.

In the last few years, hopes have emerged that simple concepts could perhaps explain the extremely complicated biomolecular processes which are now known to a greater accuracy. In parallel, powerful methods in physics, especially nonlinearity and co-operative effects, have been developed. They apply especially to biological phenomena and can explain coherent excitations with remarkable properties. This book provides a pedagogical introduction to the theory of nonlinear excitations and solutions in a biological environment, and also to the structure and function of biomolecules as well as energy and charge transport in biophysics.

This work presents geometric and topological properties of quasicrystals and studies diffraction theory of long-range objects with non-trivial order. The book aims to provide a rigorous framework for sequences generation and Fourier analysis. In addition, great care is taken to explain the physical implications of the mathematical concepts.

This volume seeks to understand biological processes by taking a multi-disciplinary approach, employing the tools of biology, chemistry and physics. These approaches focus on biomacromolecules and their functions, which includes how they interact and react, and how information is transmitted between them. The text concentrates on quantum mechanical simulation techniques, which have developed rapidly in recent years. This covers quantum mechanical calculations of large systems, molecular dynamics combining quantum and classical algorithms, quantum dynamical simulations, and electron-proton transfer processes in proteins and solutions.

Catalytic reactions on metals are still nowadays involved in more than half of the chemical industrial processes. The winter school held at "I 'Ecole de in March 1996, 13 years after the first one, accounts Physique des Houches" for an evolution of the field in several directions. First, the emulation between theoretical chemistry and solid state physics has emerged on heuristic concepts, leading not only to explanations of the observed phenomena but, for the first time, to predictions of the reactivity of catalytic systems and of the reaction pathways. The second domain which during these years has become of primary importance is the abatement of the pollution. It concerns not only the conversion of polluting effluents but more and more major modifications of the processes to avoid the production of undesired products. Two striking examples are the necessary catalytic conversion of the 100 000 cubic meter of hydrogen that would be produced in a major incident of a nuclear power plant and the replacement of the CFC. The valorization of agricultural supplies can already be considered as one of the major achievement of catalysis. Indeed, the carbon of biosustainable raw materials represents more than 2 orders of magnitude the amount extracted from fossil fuels each year. Moreover, the molecules are already highly functionalised in contrast with hydrocarbons which require costly steps to be converted to the same products. They are now of current use in the elaboration of cosmetics, vitamins, polymers, etc.

This book is an excellent introduction to the concept of scale invariance, which is a growing field of research with wide applications. It describes where and how symmetry under scale transformation (and its various forms of partial breakdown) can be used to analyze solutions of a problem without the need to explicitly solve it. The first part gives descriptions of tools and concepts; the second is devoted to recent attempts to go beyond the invariance or symmetry breaking, to discuss causes and consequences, and to extract useful information about the system. Examples are carefully worked out in fields as diverse as condensed matter physics, population dynamics, earthquake physics, turbulence, cosmology and finance.

Among the several distinct ways of formulating and quantizing a Hamiltonian system, the light cone approach enjoys a special status because it has the largest stability group. The aim of this volume is to present achievements and open problems in this rather unusual quantization framework to a large audience. The formulation is set up in the introduction where the issues are also indicated with specific examples: vacuum structure, signature of non-perturbative effects, chiral symmetry breaking, light cone gauge theories, and more. The chapters that follow address these topics through a selection of the most relevant contributions presented at Les Houches.

Starbursts are regions of unusually rapid star formation often located in the central parts of galaxies. Recent observational and theoretical developments have emphasized their importance to understand the connection between star formation, the interstellar medium, and the secular evolution of galaxies. In this book, leading experts in the field introduce the basic processes involved in the physics of starbursts, the phenomenological concepts which are used to describe and model their triggering and evolution, and their link to galaxy formation and history. A specific effort is made to start with pedagogical presentations and to review the state-of-the art of the observations and models, emphasizing the recent breakthroughs and the major issues to be explored in the future.

The 1997 Les Houches workshop on "Dynamical Network in Physics and Biology" was the third in a series of meetings "At the Frontier between Physics and Biology". Our objective with these workshops is to create a truly interdisciplinary forum for researchers working on outstanding problems in biology, but using different approaches (physical, chemical or biological). Generally speaking, the biologists are trained in the particular and motivated by the specifics, while, in contrast, the physicists deal with generic and "universal" models. All agree about the necessity of developing "robust" models. The specific aim of the workshop was to bridge the gap between physics and biology in the particular field of interconnected dynamical networks. The proper functioning of a living organism of any complexity requires the coordinated activity of a great number of "units". Units, or, in physical terms, degrees of freedom that couple to one another, typically form networks. The physical or biological properties of interconnected networks may drastically differ from those of the individual units: the whole is not simply an assembly of its parts, as can be demonstrated by the following examples. Above a certain (critical) concentration the metallic islands, randomly distributed in an insulating matrix, form an interconnected network. At this point the macroscopic conductivity of the system becomes finite and the amorphous metal is capable of carrying current. The value of the macroscopic conductivity typically is very different from the conductivity of the individual metallic islands.

This text presents an overview of recent theoretical and experimental advances in the field of optical solitons, ranging from the mathematical foundations of integrability theory to the rapidly evolving technology of fiber soliton- based telecommunication systems. The subjects covered in the book can be broadly grouped into four main categories: optical soliton theory, fiber soliton telecommunications, optical soliton generation methods, and all-optical information processing via spatial solitons. This book should be a useful reference both for postgraduate students starting their research in the field, and researchers actively involved in nonlinear optics and optical communications.