Handling editor: Phanikrishna Thota

Center for Nonlinear Studies at Los Alamos National Laboratory by Robert Ecke

The Center for Nonlinear Studies (CNLS) was established in 1980 at Los Alamos National Laboratory to coordinate, amplify and develop the then emerging field of nonlinear science. Los Alamos had deep roots in several important areas of nonlinear science including one of the first numerical simulations of a fundamental problem in physics, namely the Fermi-Pasta-Ulam problem (1954), and much later (1978), the discovery by Mitchell Feigenbaum of the universal period-doubling route to chaos. Building on this foundation, especially in the area of numerical simulation, and with a core group of theoretical physicists and applied mathematicians, CNLS began a long tradition of research excellence in interdisciplinary research and nonlinear science. Its stated mission is fourfold:

• To identify and study fundamental nonlinear phenomena and to promote their use in applied research,
• To stimulate interdisciplinary research and the exchange of scientific ideas inside and outside the Laboratory,
• To provide a focal point for collaboration among Laboratory technical staff, academic institutions and other centers of scientific excellence, and
• To desseminate recent developments in nonlinear science and to introduce young researchers to the subject.

The Center operates by overseeing postdoctoral, student and visitor programs, organizing conferences and workshops, and acting as a focal point for laboratory research staff. The research performed at the CNLS is based on foundations of nonlinear science in dynamical systems theory (stability and bifurcation theory, chaos, pattern formation, solitons) and statistical mechanics (fractals, scaling). More recently, however, nonlinear science has been identified with the study of complex and stochastic phenomena in multiscale, nonequilibrium and many-body systems. These include traditional fluid and materials problems as well as the applications of discrete mathematics to modern networks problems and the recognition of the importance of soft-matter materials that bridge hard materials and biologically-related structures. The areas of soft matter and networks point to the role CNLS has played in holding important international conferences that bring together large parts of the scientific community to understand and organize new emerging directions in science. The 2001 CNLS Annual Conference entitled "Principles of Soft Matter" and the 2003 CNLS Annual Conference entitled "Networks: Dynamics, Structure and Function" helped influence future progress in those respective fields.

CNLS students, postdoc, staff and affiliates, Spring 2006

The CNLS has a small technical and administrative staff that oversees the scientific research areas and provides administrative support. The technical staff consists of the CNLS Director Robert Ecke and the Deputy Director Zoltán Toroczkai, who share the scientific and administrative responsibilities for the Center. The systems administrator, Donald Thompson, maintains the largely Linux computer network at CNLS. The support staff at CNLS, led by Executive Administrator Ellie Vigil, ensures the professional management of the student, postdoc, and visitor programs. In addition, a full-time conference coordinator, Adam Shipman, assists in running the many workshops and conferences sponsored by CNLS (five to ten per year).

Currently CNLS has 24 postdoctoral researchers and three full-time graduate students working jointly with other technical divisions in the Laboratory. These researchers work closely with technical staff members on problems of current interest at CNLS. There is also an active summer student research program aimed primarily at graduate students. In 2006, the program will have about 20 students working for all or part of the summer months in CNLS. The student and postdoctoral researchers, as well as frequent CNLS visitors, are located in the CNLS building so as to provide the maximum opportunity for interactions among the research population. Technical staff members who participate broadly in CNLS activities are designated as CNLS Affiliates. CNLS serves the entire Laboratory research community but has a special place within the Theoretical Division. Several Groups have played an important historical and present-day role in CNLS including the Applied Math, Complex Systems, Theoretical Condensed Matter, Experimental Condensed Matter, and Theoretical Biology Groups. During the period 2002-2005, CNLS researchers produced over 250 refereed publications including 43 papers in Physical Review Letters and three in Nature.

There are three focus research areas for CNLS that change on a three-year cycle to adapt to changing scientific interests and emerging technical challenges at Los Alamos and in the greater scientific community. In 2006, the three research areas are:

• Dynamics of Complex Networks in Biology, Information and Security
  

  The dynamics of complex networks in biological and information systems are explored using a diverse set of tools including mathematical graph theory, statistical mechanics, and numerical simulation. Emphasis is on understanding how the nature of the network determines the evolution of processes on the network. Significant applications will be in cell signalling networks, protein folding networks, information networks, and in complex network systems relevant to homeland security.

• Cooperative Phenomena in Soft Matter
  

  Properties of soft matter are investigated using approaches of statistical mechanics, kinetic theory, non-equilibrium transport, classical elasticity theory, and quantum dynamics. Applications in physical, chemical and biological systems include granular flows, vesicles and membranes, polyelectrolyte assemblies, structure-geometry function relationships in macromolecules, self-assembling structures, localization in biomolecules, single-molecule dynamics and the behavior of molecular machines. We also investigate aspects of statistical hydrodynamics where statistical mechanics is applied to nonlinear multi-scale problems such as fully-developed turbulence.

• Nonlinear Behavior in Complex Systems
  

  Complex systems of physical, chemical and biological origin and man-made design and construction are explored using methods of nonlinear science including dynamical systems, pattern formation and localized-state concepts, combined with techniques of nonequilibrium statistical mechanics, mathematical physics and applied mathematics. Our approach to complex systems problems includes a combined experimental, numerical and theoretical approach whenever possible. Of particular interest are biologically-relevant localized states, novel interactions of macroscopic objects with quantum systems, design and implementation of electronic architectures using spin transport, nonequilibrium behavior of materials under high-strain-rate conditions, and science-based prediction of complex states.

CNLS encourages applications from strong scientific researchers for participation in the CNLS Student, Postdoc and Visitor programs. These programs are open to both US citizens and foreign nationals. CNLS continues to serve as a national resource in nonlinear science and complex phenomena by promoting new, exciting research in these areas, by organizing international conferences on important scientific topics, and by being a conduit for information flow between scientific centers of excellence and Laboratory programs serving science and national security.