Obtaining Breathers in Nonlinear Hamiltonian Lattices

We present a numerical method for obtaining high-accuracy numerical solutions of spatially localized time-periodic excitations on a nonlinear Hamiltonian lattice. We compare these results with analytical considerations of the spatial decay. We show that nonlinear contributions have to be considered, and obtain very good agreement between the latter and the numerical results. We discuss further applications of the method and results.Comment: 21 pages (LaTeX), 8 figures in ps-files, tar-compressed uuencoded file, Physical Review E, in pres

Anaerobic growth and potential for amino acid production by nitrate respiration in Corynebacterium glutamicum

The original publication is available at www.springerlink.com.ArticleAPPLIED MICROBIOLOGY AND BIOTECHNOLOGY. 75(5): 1173-1182 (2007)journal articl

Discrete breathers in dc biased Josephson-junction arrays

We propose a method to excite and detect a rotor localized mode (rotobreather) in a Josephson-junction array biased by dc currents. In our numerical studies of the dynamics we have used experimentally realizable parameters and included self-inductances. We have uncovered two families of rotobreathers. Both types are stable under thermal fluctuations and exist for a broad range of array parameters and sizes including arrays as small as a single plaquette. We suggest a single Josephson-junction plaquette as an ideal system to experimentally investigate these solutions.Comment: 5 pages, 5 figure, to appear June 1, 1999 in PR

Chaotic transients in the switching of roto-breathers

By integrating a set of model equations for Josephson ladder subjected to a uniform transverse bias current we have found almost all of the kinds of breathers described in recent experiments, and closely reproduced their voltage-current characteristics and switching behaviour. Our main result is that a chaotic transient occurs in the switching process. The growth of tiny perturbations during the chaotic transient causes the new breather configuration to be extremely sensitive to the precise history of the initial breather and can also cause the new breather to have a new centre of symmetry.Comment: 6 pages, 4 figure

Supersonic Discrete Kink-Solitons and Sinusoidal Patterns with "Magic" wavenumber in Anharmonic Lattices

The sharp pulse method is applied to Fermi-Pasta-Ulam (FPU) and Lennard-Jones (LJ) anharmonic lattices. Numerical simulations reveal the presence of high energy strongly localized ``discrete'' kink-solitons (DK), which move with supersonic velocities that are proportional to kink amplitudes. For small amplitudes, the DK's of the FPU lattice reduce to the well-known ``continuous'' kink-soliton solutions of the modified Korteweg-de Vries equation. For high amplitudes, we obtain a consistent description of these DK's in terms of approximate solutions of the lattice equations that are obtained by restricting to a bounded support in space exact solutions with sinusoidal pattern characterized by the ``magic'' wavenumber $k=2\pi/3$. Relative displacement patterns, velocity versus amplitude, dispersion relation and exponential tails found in numerical simulations are shown to agree very well with analytical predictions, for both FPU and LJ lattices.Comment: Europhysics Letters (in print

Immunohistochemical detection of membrane-type-1-matrix metalloproteinase in colorectal carcinoma

We investigated whether the expression of membrane-type-1 matrix metalloproteinase (MT1-MMP), matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of metalloproteinase-2 (TIMP-2) was consistent with the proposed roles of these proteins in promoting metastasis in colorectal cancer. The expression of MT1-MMP was significantly more frequent in deeply invasive carcinomas (P = 0.007) and in cases of vascular invasion (P = 0.02). The frequency of detection of MMP-2 in the stroma was much greater in vascular invasion-positive cases (42%) than in negative cases (20%;P = 0.02). The rate of detection of TIMP-2 in tumour cell cytoplasm increased with the depth of invasion (P = 0.03). TIMP-2 in the stroma was found more frequently in tumours with lymphatic invasion and lymph node metastasis (P< 0.05). Significant correlations were found between detection of MT1-MMP and MMP-2 in tumour cell cytoplasm (P< 0.05), of MT1-MMP and TIMP-2 in tumour cell cytoplasm (P< 0.01), and of MMP-2 and TIMP-2 in tumour cell cytoplasm (P< 0.01). Immunohistochemical detection of MT1-MMP and TIMP-2 might be useful for monitoring infiltration in colorectal carcinoma but is not correlated with distant metastases. © 2000 Cancer Research Campaig

Energy Storage in a Hamiltonian System in Partial Contact with a Heat Bath

To understand the mechanism allowing for the long-term storage of excess energy in proteins, we study a Hamiltonian system consisting of several coupled pendula in partial contact with a heat bath. It is found that energy storage is possible when the motion of each pendulum switches between oscillatory (vibrational) and rotational (phase-slip) modes. The storage time increases almost exponentially to the square root of the injected energy. The relevance of our mechanism to protein motors is discussed.Comment: 8 pages, 4 figures, to appear in J.Phys.Soc.Jp