This symposium is a part of the StatPhysHK Conference held in Hong Kong on 13-16 July 2010.
Abstract:
Branching Random Walks, Directed Polymers and Genealogies
Bernard Derrida, Pierre and Marie Curie University
Models of evolution in the presence of selection can be mapped on a mean field version of the problem of directed polymers in a random medium. Analytic and numerical results indicate that the statistical properties of the genealogies in the presence of selection are identical to those of the ultrametric trees of mean field spin glasses, as predicted by the Parisi broken symmetry of replicas. The statistical properties of the fittest individuals, which in the directed polymer problem corresponds to the configurations of lowest energies, can be computed using traveling waves.
Survival of the Luckiest
Terence Hwa, University of California at San Diego
Darwinian evolution is often thought of and studied as a game of the "survival of the fittest", in which tiny fitness differences between two competing species can dominate the outcome of competition.
However, often a species is either fit or unfit given an environment; survival in this case becomes a game of finding a tolerable niche and colonizing it before competitors do. Prof Hwa will present evidences which suggest that bacteria can defeat antibiotic treatment by playing such a game. The rate of evolution via a series of such niche hopping can be much larger than climbing a smooth fitness mountain.
Critical Behaviour of Large Scale Dynamical Heterogeneities in Glasses
Giorgio Parisi, University of Rome “La Sapienza”
We show how to perform a systematic perturbative approach for the mode-coupling theory. The results coincide with those obtained via the replica approach. The upper critical dimension turns out to be always 8 and the correlations have a double pole in momentum space in perturbations theory. Non-perturbative effects are found to be very important. We suggest a possible framework to compute these effects.
Liquid Water, the “Most Complex” Liquid: New Results in Bulk, Nanoconfined, and Biological Environments
H. Eugene Stanley, Boston University
On behalf of his research group, Prof H. Eugene Stanley will introduce some of the 63 anomalies of the most complex of liquids, water. He will demonstrate some recent progress in understanding these anomalies by combining information provided by recent experiments and simulations on water in bulk, nanoconfined, and biological environments. He will interpret evidence from recent experiments designed to test the hypothesis that liquid water may display “polymorphism” in that it can exist in two different phases---and discuss recent work on water's transport anomalies as well as the unusual behavior of water in biological environments. Finally, he will discuss how the general concept of liquid polymorphism is proving useful in understanding anomalies in other liquids, such as silicon, silica, and carbon, as well as metallic glasses, which have in common that they are characterized by two characteristic length scales in their interactions.
About the speakers:
Prof Bernard Derrida did his PhD from 1975 to 1979, for the first part studying a three body problem in Saclay under the direction of Prof Michel Gaudin, and then working on dynamical systems and on spin glasses in Grenoble under the direction of Prof Philippe Nozières, Yves Pomeau and Gérard Toulouse.
From 1979 to 1993 he was a permanent member of the Theoretical Physics group in Saclay. Since 1993, he is a Professor of Physics at École Normale Supérieure and at Université Pierre et Marie Curie in Paris. He is a member of the French Academy of Sciences, and was awarded the 2010 Boltzmann medal.
Prof Derrida's best known works are on disordered systems, in particular on spin glasses where he invented very simple exactly solvable models, the random energy model in 1980 and its generalisation in 1985, which possess many features predicted by the broken symmetry of replicas of Prof Giorgio Parisi. He also made a number of other well known contributions to the theory of disordered systems, in particular on diffusion in the presence of disorder, Anderson localisation, neural networks, and directed polymers in a random medium.
Prof Terence Hwa completed his PhD in theoretical and experimental physics at MIT in 1990. He did his post-doctoral study in theoretical condensed matter physics at Harvard University from 1990 to 1993, and was a long-term member at the Institute for Advanced Study at Princeton in 1994. He has been at the University of California at San Diego since 1995 where he is currently a Professor of Physics and Biology.
Prof Hwa’s current research interest is on the interface of biology and statistical physics. His work spans bioinformatics, molecular biophysics, gene regulation, genetic circuits, metabolic coordination, microbial growth physiology, developmental biology, and molecular evolution. He is the recipient of various awards, including the Sloan and Guggenheim fellowships, Young Investigator Awards by the Beckman Foundation, the Office of Naval Research, and the Overseas Chinese Physics Association, Innovation Award by the Burroughs-Wellcome Fund. He is currently a Distinguished Visiting Professor at the Department of Physics and Department of Biochemistry, The University of Hong Kong.
Prof Giorgio Parisi received his PhD from Rome University in 1970. He worked as a researcher at the Laboratori Nazionali di Frascati from 1971 to 1981, and became full professor at Rome University in 1981. He is now professor of Quantum Theories at the University of Rome I, La Sapienza.
Prof Parisi received the Feltrinelli Prize for Physics in 1986, the Boltzmann medal in 1992, the Dirac medal and prize in 1999, the Italian Prime Minister prize in 2002, and the Galileo prize in 2006. He is a fellow of the Accademia dei Lincei, the French Academy of Sciences, the Accademia dei XL and the US National Academy of Sciences.
Prof Parisi has published 3 books and written about 500 scientific publications on reviews. His main research has been in the field of elementary particles, theory of phase transitions and statistical mechanics, mathematical physics and string theory, disordered systems (spin glasses and complex systems), neural networks, theoretical immunology, computers and very large-scale simulations of QCD (the APE project), and non-equilibrium statistical physics.
Prof H. Eugene Stanley was awarded the PhD in physics at Harvard in 1967. He joined the faculty of MIT in 1969. In 1976, he joined Boston University as Professor of Physics, and as Associate Professor of Physiology (in the School of Medicine). In 1978 and 1979, he was promoted to Professor of Physiology and University Professor, respectively. In 2007 he was offered joint appointments with the Chemistry and Biomedical Engineering Departments.
Prof Stanley’s current research focus is understanding the anomalous behavior of liquid water in bulk, nanoconfined, and biological environments. He has also worked on a range of other topics in complex systems, such as quantifying correlations among the constituents of the Alzheimer brain, and quantifying fluctuations in noncoding and coding DNA sequences, interbeat intervals of the healthy and diseased heart.
He has been elected to the US National Academy of Sciences and the Brazilian Academy of Sciences, and as an Honorary Member of the Hungarian Physical Society. In recognition of his interdisciplinary contributions to physics, chemistry, and biology, he was awarded the 2004 Boltzmann Medal, and the 2008 Julius Edgar Lilienfeld Prize.
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