Jean-Charles Gille

Stefan Wegrzyn

Pierre Vidal

Many facts were at the origin of the present monograph. The ftrst is the beauty of maple leaves in Quebec forests in Fall. It raised the question: how does nature create and reproduce such beautiful patterns? The second was the reading of A. Lindenmayer's works on L systems. Finally came the discovery of "the secrets of DNA" together with many stimulating ex changes with biologists. Looking at such facts from the viewpoint of recursive numerical systems led to devise a simple model based on six elementary operations organized in a generating word, the analog of the program of a computer and of the genetic code of DNA in the cells of a living organism. It turned out that such a model, despite its simplicity, can account for a great number of properties of living organisms, e.g. their hierarchical structure, their ability to regenerate after a trauma, the possibility of cloning, their sensitivity to mutation, their growth, decay and reproduction. The model lends itself to analysis: the knowledge of the generating word makes it possible to predict the structure of the successive developmental stages of the system; and to synthesis: a speciftc type of structure can be obtained by systematically constructing a generating word that produces it. In fact the model here proposed is coherent with the fundamental assumptions of cellular biology and in particular with recent discoveries concerning DNA, which in the light of our model behaves like a very elaborate generating word.

At the Crossroads of System Theory, Computer Science, and Genetic Engineering

Developmental SystemS

Società italiana di fisica

John C. Gille

Guido Visconti

This book is concerned with the atmosphere and how the understanding of its behavior could be facilitated by the observations and modeling of the interacting processes planned within the framework of the EOS program. The Earth Observing System (EOS) is a comprehensive scientific program aimed at observing the most important components of the Earth System, in order to develop the understanding of the basic processes that must be incorporated in comprehensive Earth System models. The contents are divided into four parts. Part 1 is an overview of the Earth Observing System concept and provides a general introduction to Earth System Science. Part 2 deals with the troposphere and includes a comprehensive introduction to the problems of tropospheric chemistry. The more traditional view of the troposphere as the stage for dynamics and meterology is also dealt with. The climate system is discussed in detail in Part 3, and includes the most important advances made in recent years in understanding some of these processes which have come from satellite observations. The final part deals with the middle atmosphere. The interest in ozone has made this region of the atmosphere the most closely studied in the last few years, in an attempt to establish how much of the changes in its composition may be attributable to natural variability and how much to anthropogenic influence.

Varenna on Lake Como, Villa Monastero, 26 June-6 July 1990

The Use of EOS for Studies of Atomospheric Physics

Jean-Charles Gille

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