Magneto-optical evidence of the percolation nature of the metal-insulator transition in the 2D electron system

We compare the results of the transport and time-resolved magneto-luminescence measurements in disordered 2D electron systems in GaAs-AlGaAs heterostructures in the extreme quantum limit, in particular, in the vicinity of the metal-insulator transition (MIT). At filling factors $\nu <1$, the optical signal has two components: the single-rate exponentially decaying part attributed to a uniform liquid and a power-law long-living tail specific to a microscopically inhomogeneous state of electrons. We interprete this result as a separation of the 2D electron system into a liquid and localized phases, especially because the MIT occurs strikingly close to those filling factors where the liquid occupies ${1\over 2}$ of the sample area (the percollation threshold condition in two-component media).Comment: 5 pages RevTex + 4 fig., to appear in PRB, Rapid Com

Generalized Haldane Equation and Fluctuation Theorem in the Steady State Cycle Kinetics of Single Enzymes

Enyzme kinetics are cyclic. We study a Markov renewal process model of single-enzyme turnover in nonequilibrium steady-state (NESS) with sustained concentrations for substrates and products. We show that the forward and backward cycle times have idential non-exponential distributions: \QQ_+(t)=\QQ_-(t). This equation generalizes the Haldane relation in reversible enzyme kinetics. In terms of the probabilities for the forward ($p_+$) and backward ($p_-$) cycles, $k_BT\ln(p_+/p_-)$ is shown to be the chemical driving force of the NESS, $\Delta\mu$. More interestingly, the moment generating function of the stochastic number of substrate cycle $\nu(t)$, follows the fluctuation theorem in the form of Kurchan-Lebowitz-Spohn-type symmetry. When $\lambda$ = $\Delta\mu/k_BT$, we obtain the Jarzynski-Hatano-Sasa-type equality: $\equiv$ 1 for all $t$, where $\nu\Delta\mu$ is the fluctuating chemical work done for sustaining the NESS. This theory suggests possible methods to experimentally determine the nonequilibrium driving force {\it in situ} from turnover data via single-molecule enzymology.Comment: 4 pages, 3 figure

Numerical Construction of LISS Lyapunov Functions under a Small Gain Condition

In the stability analysis of large-scale interconnected systems it is frequently desirable to be able to determine a decay point of the gain operator, i.e., a point whose image under the monotone operator is strictly smaller than the point itself. The set of such decay points plays a crucial role in checking, in a semi-global fashion, the local input-to-state stability of an interconnected system and in the numerical construction of a LISS Lyapunov function. We provide a homotopy algorithm that computes a decay point of a monotone op- erator. For this purpose we use a fixed point algorithm and provide a function whose fixed points correspond to decay points of the monotone operator. The advantage to an earlier algorithm is demonstrated. Furthermore an example is given which shows how to analyze a given perturbed interconnected system.Comment: 30 pages, 7 figures, 4 table

ICTV Virus Taxonomy Profile: Chrysoviridae

The Chrysoviridae is a family of small, isometric, non-enveloped viruses (40 nm in diameter) with segmented dsRNA genomes (typically four segments). The genome segments are individually encapsidated and together comprise 11.5–12.8 kbp. The single genus Chrysovirus includes nine species. Chrysoviruses lack an extracellular phase to their life cycle; they are transmitted via intracellular routes within an individual during hyphal growth, in asexual or sexual spores, or between individuals via hyphal anastomosis. There are no known natural vectors for chrysoviruses. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Chrysoviridae, which is available at www.ictv.global/report/chrysoviridae.Peer reviewe

A relativistic helical jet in the gamma-ray AGN 1156+295

We present the results of a number of high resolution radio observations of the AGN 1156+295. These include multi-epoch and multi-frequency VLBI, VSOP, MERLIN and VLA observations made over a period of 50 months. The 5 GHz MERLIN images trace a straight jet extending to 2 arcsec at P.A. -18 degrees. Extended low brightness emission was detected in the MERLIN observation at 1.6 GHz and the VLA observation at 8.5 GHz with a bend of about 90 degrees at the end of the 2 arcsecond jet. A region of similar diffuse emission is also seen about 2 arcseconds south of the radio core. The VLBI images of the blazar reveal a core-jet structure with an oscillating jet on a milli-arcsecond (mas) scale which aligns with the arcsecond jet at a distance of several tens of milli-arcseconds from the core. This probably indicates that the orientation of the jet structure is close to the line of sight, with the northern jet being relativistically beamed toward us. In this scenario the diffuse emission to the north and south is not beamed and appears symmetrical. For the northern jet at the mas scale, proper motions of 13.7 +/-3.5, 10.6 +/- 2.8, and 11.8 +/- 2.8 c are measured in three distinct components of the jet (q_0=0.5, H_0=65 km /s /Mpc are used through out this paper). Highly polarised emission is detected on VLBI scales in the region in which the jet bends sharply to the north-west. The spectral index distribution of the source shows that the strongest compact component has a flat spectrum, and the extended jet has a steep spectrum. A helical trajectory along the surface of a cone was proposed based on the conservation laws for kinetic energy and momentum to explain the observed phenomena, which is in a good agreement with the observed results on scales of 1 mas to 1 arcsec.Comment: 19 pages with 18 figures. Accepted for publication in the A&

Stripe State in the Lowest Landau Level

The stripe state in the lowest Landau level is studied by the density matrix renormalization group (DMRG) method. The ground state energy and pair correlation functions are systematically calculated for various pseudopotentials in the lowest Landau level. We show that the stripe state in the lowest Landau level is realized only in a system whose width perpendicular to the two-dimensional electron layer is smaller than the order of magnetic length.Comment: 4 pages, 6 figures, to appear in J. Phys. Soc. Jpn. vol.73 No.1 (2004

Relative Entropy: Free Energy Associated with Equilibrium Fluctuations and Nonequilibrium Deviations

Using a one-dimensional macromolecule in aqueous solution as an illustration, we demonstrate that the relative entropy from information theory, $\sum_k p_k\ln(p_k/p_k^*)$, has a natural role in the energetics of equilibrium and nonequilibrium conformational fluctuations of the single molecule. It is identified as the free energy difference associated with a fluctuating density in equilibrium, and is associated with the distribution deviate from the equilibrium in nonequilibrium relaxation. This result can be generalized to any other isothermal macromolecular systems using the mathematical theories of large deviations and Markov processes, and at the same time provides the well-known mathematical results with an interesting physical interpretations.Comment: 5 page

Real Space Effective Interaction and Phase Transition in the Lowest Landau Level

The transition between the stripe state and the liquid state in a high magnetic field is studied by the density-matrix renormalization-group (DMRG) method. Systematic analysis on the ground state of two-dimensional electrons in the lowest Landau level shows that the transition from the stripe state to the liquid state at v=3/8 is caused by a reduction of repulsive interaction around r=3. The same reduction of the interaction also stabilizes the incompressible liquid states at v=1/3 and 2/5, which shows a similarity between the two liquid states at v=3/8 and 1/3. It is also shown that the strong short-range interaction around r=1 in the lowest Landau level makes qualitatively different stripe correlations compared with that in higher Landau levels.Comment: 5 pages, to appear in J. Phys. Soc. Jpn. Vol.73, No.8 (2004

Simulation Studies on the Stability of the Vortex-Glass Order

The stability of the three-dimensional vortex-glass order in random type-II superconductors with point disorder is investigated by equilibrium Monte Carlo simulations based on a lattice XY model with a uniform field threading the system. It is found that the vortex-glass order, which stably exists in the absence of screening, is destroyed by the screenng effect, corroborating the previous finding based on the spatially isotropic gauge-glass model. Estimated critical exponents, however, deviate considerably from the values reported for the gauge-glass model.Comment: Minor modifications made, a few referenced added; to appear in J. Phys. Soc. Jpn. Vol.69 No.1 (2000

Circular polarization dependent study of the microwave photoconductivity in a two-dimensional electron system

The polarization dependence of the low field microwave photoconductivity and absorption of a two-dimensional electron system has been investigated in a quasi-optical setup in which linear and any circular polarization can be produced in-situ. The microwave induced resistance oscillations and the zero resistance regions are notedly immune to the sense of circular polarization. This observation is discrepant with a number of proposed theories. Deviations only occur near the cyclotron resonance absorption where an unprecedented large resistance response is observed.Comment: 5 pages, 3 figure