## Doctors Philosophiae Honoris Causa

Professor Peter Leth Christiansen was born in Vinding, Denmark on August 6, 1937. He graduated as an engineer specialized in experimental physics, became a Ph. D. in 1965 and received a Doctor Technices degree in 1976 at the Technical University of Denmark (TUD) in Lyngby. The theses deal with short-wavelength asymptotic diffraction theory.

Professor Christiansen's current status is professor emeritus at Informatics and Mathematical Modelling and the Department of Physics at TUD.

1965-1966 he was a research associate at The University of Michigan Radiation Laboratory and 1966-1969 assistant and associate professor at the Laboratory of Applied Mathematical Physics at TUD. He became a visiting member and associate professor at Courant Institute of Mathematical Sciences, New York University from 1969 to 1970. Between 1970 and 1999 he served as an associate professor, head and docent at the Laboratory of Applied Mathematical Physics and Department of Mathematical Modelling, TUD.

Together with colleagues at the mathematics, physics, and chemistry departments at TUD he founded Center for Modelling, Non-Linear Dynamics and Irreversible Thermodynamics (MIDIT), at TUD in 1985 and served as chairman for this international nonlinear center and as head of Graduate School in Nonlinear Science at TUD together with Riso National Laboratory, Niels Bohr Institute and H. C. Orsted Institute, University of Copenhagen until 2006.

1988-1989 he was a visiting Professor at Institute for Mathematics and Its Applications, University of Minnesota, at Department of Mathematics, University of Arizona, at Center for Nonlinear Studies, Los Alamos National Laboratory, and at Dipartimento di Matematica e Applicazioni, University of Naples. In 1996 he was a visiting fellow at Optical Sciences Center, Australian National University.

In 1999 he was appointed full professor of nonlinear science at TUD and served in this capacity at Department of Informatics and Mathematical Modelling and Department of Physics until his retirement in 2004. Since then he has continued his research work on nonlinear science and its applications at these departments.

He was awarded the Rheinholdt W. Jorck and Wife's Foundation prize in 1985. In 2007 he received the honorary doctor's degree from the Bogolyubov Institute for Theoretical Physics, the National Academy of Sciences, Ukraine.

In the major part of his scientific life Professor Christiansen has been working on nonlinear problems: soliton waves in electronic superconducting components, optical systems and molecular lattices. He has also contributed to robustness studies and collapse dynamics of coherent structures under random conditions and investigated chaos and quantum chaology in certain dynamical systems. Nonlinear phenomna in biophysics are also included in the nearly 200 scienticfic papers of which he has been an author or a co-author.

Since 1989 he has collaborated intensively with colleagues at the Bogolyubov Institute for Theoretical Physics on applications of nonlinear science within biomolecules and biomotors, optical systems and superconducting devices. He has also had longstanding collaboration with Los Alamos National Laboratory, University of Arizona, University of Salerno and other scientific institutions. He coordinated and participated in four networks sponsored by the European Union on Superconduction, Nonlinear Approach to Coherent and Fluctuating Processes in Condensed Matter and Optical Physics, and Localisation by Nonlinearity and Spatial Discreteness.

He was editor of Journal of Biological Physics (1991-1997) and Physica Scripta (1989-1999) and has edited 7 books and conference proceedings.

In his (partial) otium he plays the Danish puppet theatre for his grandchildren and other patient spectators and listens to classical music.