Self-healing slip pulses along a gel/glass interface

We present experimental evidence of self-healing shear cracks at a gel/glass interface. This system exhibits two dynamical regimes depending on the driving velocity: steady sliding at high velocity (>V(c) approximately 100--125 microm/s), characterized by a shear-thinning rheology, and periodic stick-slip dynamics at low velocity. In this last regime, slip occurs by propagation of pulses that restick via a "healing instability" occurring when the local sliding velocity reaches the macroscopic transition velocity V(c). At driving velocities close below V(c), the system exhibits complex spatiotemporal behavior.     

Multispecies pair annihilation reactions

We consider diffusion-limited reactions A(i)+A(j)--> (1< or =i2 and d> or =2, we argue that the asymptotic density decay for such mutual annihilation processes with equal rates and initial densities is the same as for single-species pair annihilation A+A-->. In d=1, however, particle segregation occurs for all q< infinity. The total density decays according to a q dependent power law, rho(t) approximately t(-alpha(q)). Within a simplified version of the model alpha(q)=(q-1)/2q can be determined exactly. Our findings are supported through Monte Carlo simulations.     

Inverse proximity effect in a strongly correlated electron system

An anomalous superconducting proximity effect between a strongly correlated electron system and a normal metal is demonstrated. The model system is a 2D ultrathin superconducting quench-condensed Pb film. Such a highly disordered film has a reduced transition temperature (T(c) = 1.7 K) due to the strong e(-)-e(-) interaction. Instead of weakening the superconductivity, an overlayer of Ag on Pb induces an increase of both the T(c) and the gap. The restoration of the electron screening brought about by the quasiparticles from the normal metal can explain this striking inverse proximity effect.     

Unprecedented zwitterion in quinonoid chemistry

The first 12 pi-electron zwitterionic structure in quinonoid chemistry is described with the N,N,O,O-molecule 6 in which the positive charge is pi-delocalized between the nitrogen atoms and the negative charge between the oxygen atoms; depending on the crystallization solvent, a 1D-tape-like H-bonded network can be generated in the solid-state.     

Laplace Transform of Temperate Holomorphic Functions

Let V be n-dimensional complex vector space. The aim of this paper is to give an elementary proof of the isomorphism O ^t _V ^{^}[n] O ^t _V*, which quantizes the Fourier–Sato transform of the conic sheaf O ^t _V of temperate holomorphic functions     

Extremal Forex Returns in Extremely Large Data Sets

Exciting information for risk and investment analysis is obtained from an exceptionally large and automatically filtered high frequency data set containing all the forex quote prices on Reuters during a ten-year period. It is shown how the high frequency data improve the efficiency of the tail risk cum loss estimates. We demonstrate theoretically and empirically that the heavy tail feature of foreign exchange rate returns implies that position limits for traders calculated under the industry standard normal model are either not prudent enough, or are overly conservative depending on the time horizon.     

Dual-based error analysis for uncertainty quantification in a chemical system

An a posteriori error estimation for the numerical solution of a stochastic variational problem arising in the context of parametric uncertainty is presented. The discretization of the stochastic variational problem uses piecewise continuous orthogonal polynomials in the stochastic domain. The a posteriori methodology is derived by measuring the error as the functional difference between the continuous and discrete solutions. An example is shown on a chemical system which reaction rates are uncertain. The present approach efficiency in providing a good accuracy in the uncertainty quantification at a reasonable computational cost is demonstrated. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Aspect-ratio dependence of transient Taylor vortices close to threshold

We perform a detailed numerical study of transient Taylor vortices arising from the instability of cylindrical Couette flow with the exterior cylinder at rest for radius ratio η = 0.5 and variable aspect ratio Γ. The result of Abshagen et al. (J Fluid Mech 476:335–343, 2003) that onset transients apparently evolve on a much smaller time–scale than decay transients is recovered. It is shown to be an artefact of time scale estimations based on the Stuart–Landau amplitude equation which assumes frozen space dependence while full space–time dependence embedded in the Ginzburg–Landau formalism needs to be taken into account to understand transients already at moderate aspect ratio. Sub-critical pattern induction is shown to explain the apparently anomalous behaviour of the system at onset while decay follows the Stuart–Landau prediction more closely. The dependence of time scales on boundary effects is studied for a wide range of aspect ratios, including non-integer ones, showing general agreement with the Ginzburg–Landau picture able to account for solutions modulated by Ekman pumping at the disks bounding the cylinders.      

Parallel constrained molecular dynamics

A block version of the Shake method for heavy atom simulation in biological systems is presented in this paper. The method solves successively, independent blocks of constraints of small size by a Newton method. This algorithm is implemented in TAKAKAW, an efficient parallel molecular dynamics code. This method has been tested on a small system and on an ionic canal of 67671 atoms. This revised version was published online in June 2006 with corrections to the Cover Date.