Permutation complexity via duality between values and orderings

We study the permutation complexity of finite-state stationary stochastic processes based on a duality between values and orderings between values. First, we establish a duality between the set of all words of a fixed length and the set of all permutations of the same length. Second, on this basis, we give an elementary alternative proof of the equality between the permutation entropy rate and the entropy rate for a finite-state stationary stochastic processes first proved in [J.M. Amigó, M.B. Kennel, L. Kocarev, The permutation entropy rate equals the metric entropy rate for ergodic information sources and ergodic dynamical systems, Physica D 210 (2005) 77-95]. Third, we show that further information on the relationship between the structure of values and the structure of orderings for finite-state stationary stochastic processes beyond the entropy rate can be obtained from the established duality. In particular, we prove that the permutation excess entropy is equal to the excess entropy, which is a measure of global correlation present in a stationary stochastic process, for finite-state stationary ergodic Markov processes.     

Optical guidance of terrawatt laser pulses by the implosion phase of a fast Z-pinch discharge in a gas-filled capillary

A new method of optical guidance by the implosion phase of a fast Z-pinch discharge in a gas-filled capillary is proposed. An imploding plasma column has a concave electron-density profile in the radial direction, just before a stagnation phase driven by a converging current sheet and a shock wave. The feasibility of optical guidance of a high-intensity (>1 x 10(17) W/cm(2)) Ti:sapphire laser pulse by use of this method over a distance of 2 cm, corresponding to 12.5 times the Rayleigh length, has been experimentally demonstrated. The guiding-channel formation process was directly probed with a He-Ne laser beam. The electron density in the fully ionized channel was estimated to be 2.0 x 10(17) cm(-3) on the axis and 7.0 x 10(17) cm(-3) on the peaks of the channel edge, with a diameter of 70 mum, as indicated by the experimental results, which were corroborated by a magnetohydrodynamics simulation.     

Infrared Features of Unquenched Lattice Landau Gauge QCD

The running coupling and the Kugo-Ojima parameter of unquenched lattice Landau gauge are simulated and compared with the continuum theory. Although the running coupling measured by the ghost and gluon dressing function is infrared suppressed, the running coupling has a maximum of α₀ ∼ 2 − 2.5 at around q = 0.5 GeV irrespective of the fermion actions (Wilson fermions and Kogut-Susskind (KS) fermions). The Kugo-Ojima parameter c which saturated to about 0.8 in quenched simulations becomes consistent with 1 in the MILC configurations produced with the use of the Asqtad action, after averaging the dependence on polarization directions caused by the asymmetry of the lattice. The presence of the correction factor 1 + c ₁/q ² in the running coupling depends on the lattice size and the sea quark mass. In the large lattice size and small sea quark mass, c ₁ is confirmed of the order of a few GeV. The MILC configuration of a = 0.09 fm suggests also the presence of dimension-4 condensates with a sign opposite to the dimension-2 condensates. The gluon propagator, the ghost propagator, and the running coupling are compared with recent pQCD results including an anomalous dimension of fields up to the four-loop level.     

Critical current density and vortex dynamics in uranium irradiated Co-doped BaFe2As2

We report the effect of defects introduced by heavy-ion irradiation with 2.6 GeV uranium ions at several matching fields in single crystalline Ba(Fe_0.925Co_0.075)₂As₂. The suppression rate of T_c at lower matching fields is larger than that at higher matching fields. The critical current density calculated from magnetic hysteresis loop is enhanced up to 4.1 × 10⁶ A/cm² at 2 K. Clear dips in magnetic hysteresis loops near zero field are observed at high matching fields. Field dependence of normalized relaxation rate is suppressed, and the relationship between the dip and the relaxation rate is discussed.     

Strained layer quantum well semiconductor optical amplifiers: Polarization insensitive amplification

Polarization insensitive optical amplification was demonstrated in newly developed semiconductor optical amplifiers that have strained GalnAsP quantum well structures. We tailored the active region of the quaternary strained layer quantum well structure with a small biaxially tensile strain of 0.2% in the well layers for polarization insensitive operation.     

Sorption of water vapor into polyelectrolyte complex of poly(styrenesulfonic acid)/poly(4-vinyl-N-ethylpyridinium bromide)

Successive differential and integral sorptions of water vapor into the polyelectrolyte complex of poly (sty renesulfonic acid) / poly(4-vinyl-N-ethylpyridinum bromide) have been measured; films of stoichiometric (1/1 molar ratio) and nonstoichiometric (2/1 molar ratio) complex were employed in the experiments. Sorption isotherms have been also determined by using the values obtained from integral sorption experiments. The sorption data have suggested the following. (i) The rearrangement of polymer chains plays a relatively unimportant role in sorption of water. (ii) The relaxation motion of network chains is suppressed. (iii) The change of morphological structure caused by vapor sorption is obscure. (iv) The ionic character of the 1/1 complex is higher than that of 2/1 complex. (v) A small amount of water can be dispersed on specific polymer sites, but the sorption of a large amount of water is accompanied by an expansion of network structure. Points (i)-(v) have been consistently interpreted on the basis of the network structure and ionic character of this complex.     

SILEX-1装置上等离子体尾场加速电子初步实验

激光等离子体加速电子机制可以产生准单能的高能电子束, 近年来成为国际上的研究热点. 中国工程物理研究院激光装置已经能够达到286TW的输出功率, 为国内在该领域的研究提供了实验条件. 文章介绍了在SILEX-1装置上开展的激光等离子体加速电子的初步实验, 并对测得结果进行讨论, 为下一步实验的进行提供了准备条件.