Local electromigration model for crystal surfaces

We analyze the dynamics of crystal surfaces in the presence of electromigration. From a phase field model with a migration force which depends on the local geometry, we derive a step model with additional contributions in the kinetic boundary conditions. These contributions trigger various surface instabilities, such as step meandering, bunching and pairing on vicinal surfaces. Experiments are discussed

Higher Order Corrections to the Asymptotic Perturbative Solution of a Schwinger-Dyson Equation

Building on our previous works on perturbative solutions to a Schwinger-Dyson for the massless Wess-Zumino model, we show how to compute 1/n corrections to its asymptotic behavior. The coefficients are analytically determined through a sum on all the poles of the Mellin transform of the one loop diagram. We present results up to the fourth order in 1/n as well as a comparison with numerical results. Unexpected cancellations of zetas are observed in the solution, so that no even zetas appear and the weight of the coefficients is lower than expected, which suggests the existence of more structure in the theory.Comment: 16 pages, 2 figures. Some points clarified, typos corrected, matches the version to be published in Lett. Math. Phy

Experimental study of depolarization and antenna correlation in tunnels in the 1.3 GHz band

Measurements have been carried out in a low-traffic road tunnel to investigate the influence of the polarization of the transmitting and receiving antennas on the channel characteristics. A real-time channel sounder working in a frequency band around 1.3 GHz has been used, the elements of the transmitting and receiving arrays being dual-polarized patch antennas. Special emphasis is made on cross-polarization discrimination factor and on the spatial correlation between array elements which has a great influence on the performances of transmit/receive diversity schemes. Various polarizations both at the transmitter and the receiver have been tested to minimize this spatial correlation while keeping the size of the array as small as possible

Friedel oscillations in a Luttinger liquid with long-range interactions

We introduce a path-integral approach that allows to compute charge density oscillations in a Luttinger liquid with impurities. We obtain an explicit expression for the envelope of Friedel oscillations in the presence of arbitrary electron-electron potentials. As examples, in order to illustrate the procedure, we show how to use our formula for contact and Coulomb potentials.Comment: 11 pages, no figures, latex. Revised version to appear in PR

Dealing with Internal Inconsistency in Double-Bounded Dichotomous Choice: An Application to Community-Based Health Insurance

Contingent valuation method is commonly used in the field of health economics in an attempt to help policy maker in taking decisions. The use of the double-bounded dichotomous choice format results in a substantial gain in statistical efficiency over the single bounded dichotomous choice format. Yet, this efficiency gain comes at the cost of biasness known as internal inconsistency. This paper aims at reducing this internal inconsistency in double-bounded dichotomous choice by using the certainty calibration technique in a community-based health insurance study. Findings confirm the internal inconsistency between the initial and the follow-up responses and the statistical efficiency gains of the double-bounded dichotomous choice over the single-bounded dichotomous choice. Furthermore, the use of certainty calibration reduces this internal inconsistent pattern in responses and still maintains efficiency gain. We further discuss the policy implications.Contingent valuation; internal inconsistency; certainty calibration; community-based health insurance

Using parallel computation to improve Independent Metropolis--Hastings based estimation

In this paper, we consider the implications of the fact that parallel raw-power can be exploited by a generic Metropolis--Hastings algorithm if the proposed values are independent. In particular, we present improvements to the independent Metropolis--Hastings algorithm that significantly decrease the variance of any estimator derived from the MCMC output, for a null computing cost since those improvements are based on a fixed number of target density evaluations. Furthermore, the techniques developed in this paper do not jeopardize the Markovian convergence properties of the algorithm, since they are based on the Rao--Blackwell principles of Gelfand and Smith (1990), already exploited in Casella and Robert (1996), Atchade and Perron (2005) and Douc and Robert (2010). We illustrate those improvements both on a toy normal example and on a classical probit regression model, but stress the fact that they are applicable in any case where the independent Metropolis-Hastings is applicable.Comment: 19 pages, 8 figures, to appear in Journal of Computational and Graphical Statistic

Non Equilibrium Noise as a Probe of the Kondo Effect in Mesoscopic Wires

We study the non-equilibrium noise in mesoscopic diffusive wires hosting magnetic impurities. We find that the shot-noise to current ratio develops a peak at intermediate source-drain biases of the order of the Kondo temperature. The enhanced impurity contribution at intermediate biases is also manifested in the effective distribution. The predicted peak represents increased inelastic scattering rate at the non-equilibrium Kondo crossover.Comment: 4+ pages, 4 figures, published versio