Universality in active chaos

Many examples of chemical and biological processes take place in large-scale environmental flows. Such flows generate filamental patterns which are often fractal due to the presence of chaos in the underlying advection dynamics. In such processes, hydrodynamical stirring strongly couples into the reactivity of the advected species and might thus make the traditional treatment of the problem through partial differential equations difficult. Here we present a simple approach for the activity in in-homogeneously stirred flows. We show that the fractal patterns serving as skeletons and catalysts lead to a rate equation with a universal form that is independent of the flow, of the particle properties, and of the details of the active process. One aspect of the universality of our appraoch is that it also applies to reactions among particles of finite size (so-called inertial particles).Comment: 10 page

Mixings of 4-quark components in light non-singlet scalar mesons in QCD sum rules

Mixings of 4-quark components in the non-singlet scalar mesons are studied in the QCD sum rules. We propose a formulation to evaluate the cross correlators of q\bar q and qq\bar q \bar q operators and to define the mixings of different Fock states in the sum rule. It is applied to the non-singlet scalar mesons, a_0 and K_0^\ast. It is found that the 4-quark operators predict lower masses than the q\bar q operators and that the 4-quark states occupy about 70-90% of the lowest mass states.Comment: 8 pages, 9 figure

From electrons to Janskys: Full stokes polarized radiative transfer in 3D relativistic particle-in-cell jet simulations

The underlying plasma composition of relativistic extragalactic jets remains largely unknown. Relativistic magnetohydrodynamic (RMHD) models are able to reproduce many of the observed macroscopic features of these outflows. The nonthermal synchrotron emission detected by very long baseline interferometric (VLBI) arrays, however, is a by-product of the kinetic-scale physics occurring within the jet, physics that is not modeled directly in most RMHD codes. This paper attempts to discern the radiative differences between distinct plasma compositions within relativistic jets using small-scale 3D relativistic particle-in-cell (PIC) simulations. We generate full Stokes imaging of two PIC jet simulations, one in which the jet is composed of an electron-proton ($e^{-}$-$p^{+}$) plasma (i.e., a normal plasma jet), and the other in which the jet is composed of an electron-positron ($e^{-}$-$e^{+}$) plasma (i.e., a pair plasma jet). We examined the differences in the morphology and intensity of the linear polarization (LP) and circular polarization (CP) emanating from these two jet simulations. We find that the fractional level of CP emanating from the $e^{-}$-$p^{+}$ plasma jet is orders of magnitude larger than the level emanating from an $e^{-}$-$e^{+}$ plasma jet of a similar speed and magnetic field strength. In addition, we find that the morphology of both the linearly and circularly polarized synchrotron emission is distinct between the two jet compositions. We also demonstrate the importance of slow-light interpolation and we highlight the effect that a finite light-crossing time has on the resultant polarization when ray-tracing through relativistic plasma.Comment: 21 pages, 13 figures; accepted for publication in A&

Non-relativistic Collisionless Shocks in Unmagnetized Electron-Ion Plasmas

We show that the Weibel-mediated collisionless shocks are driven at non-relativistic propagation speed (0.1c < V < 0.45c) in unmagnetized electron-ion plasmas by performing two-dimensional particle-in-cell simulations. It is shown that the profiles of the number density and the mean velocity in the vicinity of the shock transition region, which are normalized by the respective upstream values, are almost independent of the upstream bulk velocity, i.e., the shock velocity. In particular, the width of the shock transition region is ~100 ion inertial length independent of the shock velocity. For these shocks the energy density of the magnetic field generated by the Weibel-type instability within the shock transition region reaches typically 1-2% of the upstream bulk kinetic energy density. This mechanism probably explains the robust formation of collisionless shocks, for example, driven by young supernova remnants, with no assumption of external magnetic field in the universe.Comment: 4 pages, 7 figures, accepted for publication in ApJ Letter

Evolution of the electronic structure from electron-doped to hole-doped states in the two-dimensional Mott-Hubbard system La1.17-xPbxVS3.17

The filling-controlled metal-insulator transition (MIT) in a two-dimensional Mott-Hubbard system La1.17-xPbxVS3.17 has been studied by photoemission spectroscopy. With Pb substitution x, chemical potential mu abruptly jumps by ~ 0.07 eV between x=0.15 and 0.17, indicating that a charge gap is opened at x ~= 0.16 in agreement with the Mott insulating state of the d2 configuration. When holes or electrons are doped into the Mott insulator of x ~= 0.16, the gap is filled and the photoemission spectral weight at mu, rho(mu), gradually increases in a similar way to the electronic specific heat coefficient, although the spectral weight remains depressed around mu compared to that expected for a normal metal, showing a pseudogap behavior in the metallic samples. The observed behavior of varrho(mu)->0 for x->0.16 is contrasted with the usual picture that the electron effective mass of the Fermi-liquid system is enhanced towards the metal-insulator boundary. With increasing temperature, the gap or the pseudogap is rapidly filled up, and the spectra at T=300 K appears to be almost those of a normal metal. Near the metal-insulator boundary, the spectra around mu are consistent with the formation of a Coulomb gap, suggesting the influence of long-range Coulomb interaction under the structural disorder intrinsic to this system.Comment: 8 pages, 12 figure

Report of CE on Metadata Adaptation – Integration

This paper reports the results of the CE on MPEG-21 Digital Item Adaptation – Integration defined in document N5182. In the original work plan definition, two main objectives were defined. The first one is to better evaluate if the current DIA Metadata Adaptation tools can fully support the integration of multiple MPEG-7 descriptions of a given content. The second objective of this CE is to evaluate if the current DIA tools allow to disable the metadata adaptation process in order to permit the delivery of “non adapted” content descriptions (e.g. for storage propose). Due to the few time available, only the first goal has been reached. The main contribution of this CE is a preliminary implementation of a metadata integration engine able to adapt Content DI. Based on this implementation, several integration experiments have been conducted to point out which integration tool can be useful

Report of CE on Metadata Adaptation – Integration

In this document the Metadata Adaptation tool presented at the Pattaya meeting has been validated, with a slightly adjusted syntax and semantics. An alternative syntax has also been proposed so as to be combined with the adaptation hint DS. This tool supports adaptation operations such as metadata integration. The presented scheme includes two descriptors, named AverageValue and InvariantProperties, that can be efficiently used by an integration engine in order to improve the quality of the integrated final description and to speed up the whole integration process. Examples and experiment results are given to support the validation of the proposed tool

Report of CE on Metadata Adaptation – Integration

This paper summarize the final results of the CE on MPEG-21 Digital Item Adaptation – Integration. The CE was started at the Shanghai meeting (see document N5182) and due to the fact that not all the expected goals were achieved the CE has been extended to the Pattaya meeting (see document N5362). In the original work plan definition, the principal objectives to better evaluate if the current DIA Metadata Adaptability tools can fully support the integration of multiple MPEG-7 descriptions of a given content. The main contribution of this CE is an enhanced implementation of the metadata integration engine presented in the previous CE report and the definition of syntax and semantic for a new MPEG-21 DIA MetadataAdaptability tool useful in a metadata integration processes

Size variance of motor evoked potential at initiation of voluntary contraction in palsy of conversion disorder

ArticlePSYCHIATRY AND CLINICAL NEUROSCIENCES. 62(3): 286-292(2008)journal articl

Ordering of the Heisenberg spin glass in four dimensions

Ordering of the Heisenberg spin glass in four dimensions (4D) with the nearest-neighbor Gaussian coupling is investigated by equilibrium Monte Carlo simulations, with particular attention to its spin and chiral orderings. It is found that the spin and the chirality order simultaneously with a common correlation-length exponent $\nu_{CG}=\nu_{SG}\simeq 1.0$, i.e., the absence of the spin-chirality decoupling in 4D. Yet, the spin-glass ordered state exhibits a nontrivial phase-space structure associated with a continuous one-step-like replica-symmetry breaking, different in nature from that of the Ising spin glass or of the mean-field spin glass. Comparison is made with the ordering of the Heisenberg spin glass in 3D, and with that of the 1D Heisenberg spin glass with a long-range power-law interaction. It is argued that the 4D might be close to the marginal dimension separating the spin-chirality decoupling/coupling regimes.Comment: to appear in Phys. Rev.