Open-charm meson elliptic flow measurement in Pb-Pb collisions at sqrt(sNN) = 2.76 TeV with ALICE at the LHC

A Large Ion Collider Experiment (ALICE) is one of the four large experiments at the Large Hadron Collider (LHC), and it is dedicated to the study of ultra-relativistic heavy-ion collisions, with the goal of investigating the properties of the high-density state of QCD matter produced in these collisions. The study of D meson production azimuthal anisotropy and the measurement of their elliptic flow (v2) can provide insight on the degree of thermalisation of charm quarks in the medium and on the charm hadronization mechanism. We present the measurement of the D+ and D0 meson v2 in Pb-Pb collisions at sqrt(sNN)=2.76 TeV at the LHC with ALICE. We discuss the details of the analysis and we show the results obtained from data samples collected in 2011.Comment: 4 pages, 4 figures, typos corrected, proceedings of HP2012 conferenc

Voting for the Electoral System: an Experiment.

The choice of the electoral system should be delegated to the citizens. However, citizens are not sufficiently informed to choose the system directly. It is argued that they may instead state their preferences for two basic characteristics of a Parliament, i.e. Governability and Representativeness. It is then possible to choose the system through a purely technical procedure. An experiment illustrates the method.

Choosing the electoral system: why not simply the best one?

The paper illustrates a simple empirical rule to choose the best electoral system for a Parliament.

On the Xenophobia of non-discriminated Ethnic Minorities

Sometimes the leaders of ethnic minority groups behave in a way that may promote xenophobia. A simple two-subject model is used to find out when this behaviour is rational. The conditions are briefly discussed with reference to the Italian case. An appendix illustrates the definition of xenophobia adopted in the paper.

The program for the simulation of electoral systems ALEX4.1: what it does and how to use it.

This paper illustrates ALEX4.1, the 2007 version of the program of simulation of electoral systems developed at ALEX, the Laboratory for Experimental and Simulative Economics of the Università del Piemonte Orientale at Alessandria, Italy. The main features of the program have been described with reference to a previous version in Bissey, Carini and Ortona, 2004; the paper may be freely downloaded from the site of the journal where it has been published, or in its working paper version from the site http://polis.unipmn.it/. The organization of this paper is, consequently, rather unusual. The next section presents only the very basic traits of the simulation program, as most details and theoretical considerations may be read in the quoted (and easy-to-find) reference. Sections 3 and 4 are the most important: they illustrate the novelties of ALEX4.1 with respect to previous versions. Section 5 is very short, as it contains only the instructions for downloading the program, and some caveats regarding its use. The core of the paper is a large appendix that contains the readme file of the package ALEX4.1. Actually, this paper should be considered a handbook for the use of ALEX4.1.

Simulation of capillary infiltration into packing structures by the Lattice-Boltzmann method for the optimization of ceramic materials

In this work we want to simulate with the Lattice-Boltzmann method in 2D the capillary infiltration into porous structures obtained from the packing of particles. The experimental problem motivating our work is the densification of carbon preforms by reactive melt infiltration. The aim is to determine optimization principles for the manufacturing of high-performance ceramics. Simulations are performed for packings with varying structural properties. Our analysis suggests that the observed slow infiltrations can be ascribed to interface dynamics. Pinning represents the primary factor retarding fluid penetration. The mechanism responsible for this phenomenon is analyzed in detail. When surface growth is allowed, it is found that the phenomenon of pinning becomes stronger. Systems trying to reproduce typical experimental conditions are also investigated. It turns out that the standard for accurate simulations is challenging. The primary obstacle to overcome for enhanced accuracy seems to be the over-occurrence of pinning

Coarse-graining MARTINI model for molecular-dynamics simulations of the wetting properties of graphitic surfaces with non-ionic, long-chain and T-shaped surfactants

We report on a molecular dynamics investigation of the wetting properties of graphitic surfaces by various solutions at concentrations 1-8 wt% of commercially available non-ionic surfactants with long hydrophilic chains, linear or T-shaped. These are surfactants of length up to 160 [\AA]. It turns out that molecular dynamics simulations of such systems ask for a number of solvent particles that can be reached without seriously compromising computational efficiency only by employing a coarse-grained model. The MARTINI force field with polarizable water offers a framework particularly suited for the parameterization of our systems. In general, its advantages over other coarse-grained models are the possibility to explore faster long time scales and the wider range of applicability. Although the accuracy is sometimes put under question, the results for the wetting properties by pure water are in good agreement with those for the corresponding atomistic systems and theoretical predictions. On the other hand, the bulk properties of various aqueous surfactant solutions indicate that the micellar formation process is too strong. For this reason, a typical experimental configuration is better approached by preparing the droplets with the surfactants arranged in the initial state in the vicinity of contact line. Cross-comparisons are possible and illuminating, but equilibrium contanct angles as obtained from simulations overestimate the experimental results. Nevertheless, our findings can provide guidelines for the preliminary assessment and screening of surfactants. [See pdf file for full abstract]Comment: Revised version. Publication: http://dx.doi.org/10.1063/1.4747827. Material: https://sites.google.com/site/material4sim