Reducing Urban Pollution Exposure from Road Transport(RUPERT)

This paper presents the preliminary results of a two-year study on reducing urban pollution exposure from road transport (RUPERT). The main aim of this project is to develop a new modelling framework for nitrogen dioxide, carbon monoxide and particulate matter to simulate exposures of different population groups across a city, and to assess the impact of roadside concentrations on these exposures. This will be achieved by modelling the frequency distribution of personal exposures (PEFDs) as a function of urban background and roadside concentrations, under different traffic conditions. The modelling approach combines new and existing models relating traffic and air pollution data, with particular emphasis of the impact of congestion, and the probabilistic modelling framework of personal exposure. Modelling of roadside concentrations consists of two main elements, namely the analysis of concentrations patterns at different roadside sites and of the relationship between traffic conditions and added roadside pollution. Roadside concentrations are predicted using empirically derived relationships; statistical models, novel statistics and artificial neural networks namely feed forward neural network and radial basis neural network. The exposure modelling is carried out by linking two models: the INDAIR model, which is designed to simulate probabilistically diurnal profiles of air pollutant concentrations in a range of microenvironments, and the EXPAIR model, which is designed to simulate population exposure patterns based on population time-activity patterns and a library of micro-environmental concentrations derived from the INDAIR model

Aspects of Dielectric Breakdown in a Model for Disordered Nonlinear Composites

We study dielectric breakdown in a semi-classical bond percolation model for nonlinear composite materials introduced by us and the related breakdown exponent near the percolation threshold in two dimensions. The breakdown exponent after doing finite size scaling analysis is found to be $t_B \simeq$ 1.42. We discuss in detail the differences in our model from the traditional models for dielectric breakdown and argue that our result seems to be different from the standard result of 4/3 obtained in the previous models.Comment: 20 pages, LaTex file (6 postscript figures included

Detector Time Offset and Off-line Calibration in EAS Experiments

In Extensive Air Shower (EAS) experiments, the primary direction is reconstructed by the space-time pattern of secondary particles. Thus the equalization of the transit time of signals coming from different parts of the detector is crucial in order to get the best angular resolution and pointing accuracy allowed by the detector. In this paper an off-line calibration method is proposed and studied by means of proper simulations. It allows to calibrate the array repeatedly just using the collected data without disturbing the standard acquisition. The calibration method is based on the definition of a Characteristic Plane introduced to analyze the effects of the time systematic offsets, such as the quasi-sinusoidal modulation on azimuth angle distribution. This calibration procedure works also when a pre-modulation on the primary azimuthal distribution is present.Comment: 9 pages, 5 figures, submitted to Astroparticle Physic

Relaxation of thermo-remanent magnetization in Fe-Cr GMR multilayers

The time decay of the thermo-remanent magnetization (TRM) in Fe-Cr giant magnetoresistive (GMR) multilayers has been investigated. The magnetization in these multilayers relaxes as a function of time after being cooled in a small magnetic field of 100 Oe to a low temperature and then the magnetic field is switched off. Low-field ($<$ 500 Oe) magnetization studies of these samples have shown hysteresis. This spin-glass-like behavior may originate from structural imperfections at the interfaces and in the bulk. We find that the magnetization relaxation is logarithmic. Here the magnetic viscosity is found to increase first with increasing temperature, then it reaches a maximum around T$_g$, and then it decreases with increasing temperature. This behavior is different from that of conventional spin glasses where the logarithmic creep rate is observed to increase with temperature. Power law also gives good fits and it is better than the logarithmic fit at higher temperatures. The dynamical effects of these multilayers are related to the relaxation of thermally blocked superparamagnetic grains and magnetic domains in the film layers.Comment: 19 page

Superconductivity at 11.3 K induced by cobalt doping in CeOFeAs

Pure phases of a new oxyarsenide superconductor of the nominal composition CeOFe0.9Co0.1As was successfully synthesized by solid state reaction in sealed silica ampoules at 1180 C. It crystallizes in the layered tetragonal ZrCuSiAs type structure (sp gp P4/nmm) with lattice parameter of a = 3.9918(5) angstrom and c = 8.603(1) angstrom. A sharp superconducting transition is observed at 11.31 K with an upper critical field of 45.22 T at ambient pressure. The superconducting transition temperature is drastically lowered (~ 4.5, 4.9 K) on increasing the concentration (x = 0.15, 0.2) of cobalt

First heterometallic GaIII-DyIII single-molecule magnets: Implication of GaIII in extracting Fe-Dy interaction

The compounds of the system [M4M′2(μ3-OH)2(nbdea)4(C6H5CO2)8]·MeCN, where M = GaIII, M′ = DyIII (2), M = FeIII, M′ = YIII (3) are isostructural to the known [Fe4Dy2] compound (1). Those of the system [M4M′4(μ3-OH)4(nbdea)4(m-CH3C6H4CO2)12]·nMeCN, where M = GaIII, M′ = DyIII, n = 4 (5), M = FeIII, M′ = YIII, n = 1 (6) are isostructural to the [Fe4Dy4] compound (4). This allows for comparisons between single ion effects of the paramagnetic ions. The structures were determined using single crystal analysis. Magnetic susceptibility measurements reveal that the GaIII–DyIII compounds 2 and 5 are SMMs. The energy barrier for 2 is close to that for the known isostructural Fe4Dy2 compound (1), but with a significantly increased relaxation time

Photonic production of B_c-mesons

The cross section of the $\gamma \gamma \rightarrow B_c(B_c^*) \bar b c$ process is calculated. It is shown that near threshold the pseudoscalar state production is much suppressed with respect to the vector one. At large energies their ratio becaims $\sigma(B_c^*)/sigma(B_c)\sim 4$. The process of heavy quark recombination dominates in the production of $B_c(B_c^*)$ states. The fragmentation process $b\to B_c$ comes to play at high $p_t$ values only, while its contribution will remain nondominant.Comment: Preprint IHEP 94-8

A new transient method for determining soil hydraulic conductivity function

Instantaneous profile method (IPM) is a transient method for measuring a soil hydraulic conductivity function (SHCF), which relates soil hydraulic conductivity with suction. In the existing interpretation method of the IPM, boundary flux during testing must be known to integrate instantaneous profiles of water content for obtaining water flow rate. However, it is usually difficult and expensive to measure a boundary flux and if not known, assumptions that may not be easily justified (especially in the field condition) have to be made. In this study, a new method is proposed so that any boundary flux needs not to be measured, controlled or assumed during a test. The new method is evaluated through (i) hypothetical column tests using transient seepage analyses and (ii) five case studies. The new method is capable of determining a SHCF with good accuracy. Normalised root-mean-square deviation (NRMSD) for the old and new methods is less than 5% and 10%, respectively. The accuracy of the new method can be increased substantially (i.e., NRMSDThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Superconducting Coherence and the Helicity Modulus in Vortex Line Models

We show how commonly used models for vortex lines in three dimensional superconductors can be modified to include k=0 excitations. We construct a formula for the k=0 helicity modulus in terms of fluctuations in the projected area of vortex loops. This gives a convenient criterion for the presence of superconducting coherence. We also present Monte Carlo simulations of a continuum vortex line model for the melting of the Abrikosov vortex lattice in pure YBCO.Comment: 4 pages RevTeX, 2 eps figures included using eps

Quantum correlation in three-qubit Heisenberg model with Dzyaloshinskii-Moriya interaction

We investigate the pairwise thermal quantum discord in a three-qubit XXZ model with Dzyaloshinskii-Moriya (DM) interaction. We find that the DM interaction can increase quantum discord to a fixed value in the anti- ferromagnetic system, but decreases quantum discord to a minimum first, then increases it to a fixed value in the ferromagnetic system. Abrupt change of quantum discord is observed, which indicates the abrupt change of groundstate. Dynamics of pairwise thermal quantum discord is also considered. We show that thermal discord vanishes in asymptotic limit regardless of its initial values, while thermal entanglement suddenly disappears at finite time.Comment: 6 pages, 6 figure