Date :

 18-19, 21 May 2007 [ Announcement ]

Place :

 18-19 May: The Fei-Hwa Building (菲華樓, 2F), Chinese Culture University, Taipei

 21 May: The first meeting room on the 5th floor, Institute of Physics, Academia Sinica, Taipei

 National Center for Theoretical Sciences (Critical Phenomena and Complex Systems focus group)

 Institute of Physics, Academia Sinica (Taipei)

 Department of Physics, Chinese Culture University (Taipei)

  Miss Chia-Chi Liu (Secretary, Physics Division, NCTS)
 Tel:(886)-2-33665566; Fax:(886)-2-33665565; E-mail: ccliu@phys.ntu.edu.tw

  Mr. Lee-Min Chang (鄭立明)  (Department of Physics, Chinese Culture University)

 Tel:(886)-2-28610511 ext. 25205; Fax(886)-2-28610577; E-mail: crsspy@staff.pccu.edu.tw

Hotel Info. :

 International Hotel (陽明山國際大旅館)

 Address: 台北市陽明山湖山路一段7號

 Tel: (886)-2-28617100

 Website: http://www.ihhotel.com.tw

 If you need to reserve a room, please contact with Mr. Lee-Min Chang (鄭立明, Tel:(886)-2-28610511 ext. 25205).

 Hotel expense will be paid by yourself .

Speakers :

Dr. Bidhan Chandra Bag

Institute of Physics, Academia Sinica, TAIWAN

E-mail: bidhan@phys.sinica.edu.tw

The Role of Non-Markovian Dynamics on Protein Folding Kinetics

    In this paper we have studied the role of the non-Markovian dynamics, which is characterized by the noise correlation time, t, on protein folding kinetics. Using Langevin dynamics with correlated noise and the Go-like model for b-hairpin and ubiquitin we have calculated the folding time, t _f, at different noise correlation times. Surprisingly, the dependence of t _f on t is non-trivial: the plot t _f vs t shows two minima at low and intermediate values of t.  The noise correlation is found to accelerate the folding process up to about two times. We have shown that the departure from the Kramers’ behavior observed recently in the folding/unfolding experiments may be explained taking into account the non Markovian dynamics.

Prof. Shou-Liang Bu

Department of Physics, National Sun Yat-sen University, TAIWAN

Department of Physics, Dalian University of Technology, CHINA

E-mail: busl1972@alumni.nsysu.edu.tw

Epidemic Dynamics with Movable Individuals on Complex Networks

    On the one hand, the interactions between individuals of many real-world systems form definite topological structures, and on the other hand, the individuals themselves are movable. Here we study epidemic dynamics with movable individuals on complex networks where the susceptibles and the infected take random walk. It is shown analytically and numerically that for relatively homogeneous networks, positive thresholds with respective to the population density and infectious probability exits, whereas these two thresholds both approach zero for infinite scale-free networks. This confirms that, if the underlying topology is scale-free, the infections can spread even when the population density and infection probability are vanishingly small.

Prof. Wen Chang

Institute of Molecular Biology, Academia Sinica, TAIWAN

E-mail: mbwen@ccvax.sinica.edu.tw

Vaccinia Virus Entry

    My lab has been focusing on understanding how vaccinia virus recognizes cell surface components and how such interactions leads to virus entry into cells. Our initial studies showed that cell surface glycosaminoglycans are important for vaccinia virus attacement to cells. Vaccinia virus uses three envelope proteins H3, A27 and D8 to recognize heparan sulfates and chondroitin sulfates, respectively. Recently, we determined the vaccinia virus proteome showing that a total of 75 viral proteins in virus particles. We then found that an envelope protein G3 is essential for post-binding penetration into cells and that an envelope protein, A26, binds to extracellular matrix protein laminin on cells. These results help us understand how virus recognizes its host cells.

Prof. S.C. Cheng

Department of Physics, Chinese Culture University, TAIWAN

E-mail: sccheng@faculty.pccu.edu.tw

Collapse of Bose-Einstein Condensates in Optical Lattices

Prof. Chung-I Chou

Department of Physics, Chinese Culture University, TAIWAN

E-mail: cichou@faculty.pccu.edu.tw

Appling Genetic Algorithm to Political Districting Problem

    The aim of the Political Districting Problem is to partition a zone into electoral districts with constraints such as contiguity, population equality, etc. By using statistical physics methods, the problem can be mapped onto a q-state Potts model system, and the political constraints are written as an energy function with interactions between sites or external fields acting on the system. This problem is then transformed into an optimization problem. In this paper, we apply the genetic algorithm to Political Districting Problem.We will illustrate the evolutionary strategy for GA and compare wit.

Dr. Zh.S. Gevorkian

Institute of Physics, Academia Sinica, TAIWAN

E-mail: gevorkia@phys.sinica.edu.tw

Large Fluctuation in Molten Phase of a Heterogeneous DNA

    We have investigated sample-to-sample fluctuations of free energy in a native state of a heterogeneous DNA.  It is shown that in a molten phase they are of order of average free energy due to long-range correlations of local free energies of base pairs.  This can explain a recent experiment on sequence-dependent effects in specific heat of DNA.

Prof. M.-S. Ho

Institute of Biomedical Sciences, Academia Sinica, TAIWAN

E-mail: homs@ibms.sinica.edu.tw

The Epidemiology of Influenza Virus: from the Past to the Future MSH

Prof. Ming-Chang Huang

Center for Nonlinear and Complex Systems and Department of Physics, Chung-Yuan Christian University, TAIWAN

E-mail: ming@phys.cycu.edu.tw

Stability, Energy Landscape, and Noise of Two-Dimensional Regulation Networks for Gene Expressions

    Stochastic fluctuations are important in the regulation networks of gene expressions.  We intend to clarify the relation between the stability and correlations of fluctuations in regulation networks.  Moreover, the energy landscape for the networks are also constructed to discuss the stability. Two different networks are considered in this work. One is the autoregulation network of single gene with positive or negative feedbacks.  The other is the toggle switch of two genes.

Prof. I-Min Jiang

Department of Physics, National Sun Yat-sen University, TAIWAN

E-mail: jiang@mail.phys.nsysu.edu.tw

Some Nonliear Optical Applications in Liquid Crystals

    Three our recent works of the nonlinear optical applications in liquid crystals will be briefly reported in this presentation. First : Reorientational optical nonlinearity of nematic liquid crystal cells near the nematic-isotropic phase transition temperature. Second : A voltage-controlled multi-guide directional coupler formed ina planar nemetic liquid crystal film. Third : Surface Plasmon Enhanced Diffraction in Cholesteric Liquid Crystals.

References:

[1] Ming-Shan Tsai, I-Min Jiang, Chi-Yen Huang, and Chia-Chi Shih, 2003, Opt. Lett. 28, (2003) 2357.

[2] Ming-Shan Tsai, Chie-Tong Kuo, Shuan-yu Huang, Chia-Chi Shih, and I-Min Jiang, 2004, Appl. Phys. Lett. 85(2004) 855-857.

[3] Wen-Chi Hung, Ming-Shan Tsai , Yi-Chung Juan, I-Min Jiang, P Yeh, and Wood-Hi Cheng, 2007, App. Phys. Lett. Publish in May.

Dr. Cui-Lian Li

Institute of Physics, Academia Sinica, TAIWAN

E-mail: clli@phys.sinica.edu.tw

Kinetic Model for Morphological Transition in Heteroepitaxial Growth of Metal Films

    We use kinetic Monte Carlo simulations to study the mechanisms of both 2D-to-3D growth mode transition and the 3D/2D morphological transition of clusters in the heteroepitaxial growth of metal films. Our results show that the ratio g_E between two kinds of the second neighbor interactions play an essential role in both cases.  In general, for a constant g_E corresponding to an average 3D growth, the 3D-to-2D morphological transition of single clusters can arise from various layers, but which layer is favored depends on the strain field strength. Our simulation results agree well with the experimental data reported by Su et al. in [Phys. Rev. B 71, 07334 (2005)].
　

Prof. Hisashi Okumura

Department of Physics, School of Science, Nagoya University, JAPAN

E-mail: hokumura@tb.phys.nagoya-u.ac.jp

1. Temperature and Pressure Dependence of Peptide Studied by Multibaric-Multithermal  Molecular Dynamics Simulation

    Multibaric-multithermal simulation can escape from local-minimum free-energy states, and one can obtain accurate thermodynamic quantities as functions of any temperature and pressure from a single simulation run. We performed a multibaric-multithermal molecular dynamics simulation of an alanine dipeptide in explicit water. The multibaric-multithermal simulation sampled several states. On the other hand, the conventional isobaric-isothermal simulation was trapped in local-minimum free-energy states and sampled only a few of them. We calculated the partial molar enthalpy and partial molar volume from the multibaric-multithermal simulation. Our results were  in accord with those from Raman spectroscopy.

2. Symplectic Molecular Dynamics Integrator for Rigid-Body Molecules in the Canonical Ensemble

    We propose explicit symplectic molecular dynamics integrator for rigid-body molecules in the canonical ensemble. Employing the symplectic integrator, there is a conserved quantity which is close to Hamiltonian. Therefore, we can perform a molecular dynamics simulation more stably than by conventional nonsymplectic algorithms. We applied this algorithm to a TIP3P pure water system at 300 K and compared the time evolution of the Hamiltonian with those by the nonsymplectic algorithms. We found that the Hamiltonian was conserved well by the symplectic algorithm even for a time step of 4 fs. This time step is longer than typical values of 0.5-2 fs which are used by the conventional nonsymplectic algorithms.

Prof. Chi-Tin Shih

Department of Physics, Tunghai University, TAIWAN

E-mail: ctshih@thu.edu.tw

Electric Transport Properties of the Cancerous Mutations of the p53 Gene

    The transport properties of the p53 gene is studied by a tight-binding model. The change of the transmission coefficient is evaluated for all possible point mutations of p53. On the average, the mutations found in the tumor tissues change the transmission coefficients less than others.  The results provide a possible explanation why the cancerous mutations can get rid of the DNA-repairing mechanism and cause cancers.
　

Prof. Ming-Chya Wu

Research Center for Adaptive Data Analysis, National Central University, TAIWAN

E-mail: mcwu@phys.sinica.edu.tw

Extraction of Buried Signals from an Ikeda-type Microwave System via Empirical Mode Decomposition

    Empirical mode decomposition is employed to decode message from an Ikeda-type microwave system. Under considerations of the high-dimensional chaos encryption as well as the high masking efficiency, it is shown that a meaningful data set embedded in chaotic fluctuations can be directly filtered out in a reasonable way.  Our approach is quite different from the well-known encoding/decoding technique by use of chaos synchronization. Furthermore, our satisfactory results suggest that empirical mode decomposition can be generally applied to data mining in various systems.