Propagation of social representations

Based on a minimal formalism of social representations as a set of associated cognems, a simple model of propagation of representations is presented. Assuming that subjects share the constitutive cognems, the model proposes that mere focused attention on the set of cognems in the field of common conscience may replicate the pattern of representation from context into subjects, or, from subject to subject, through actualization by language, where cognems are represented by verbal signs. Limits of the model are discussed, and evolutionist perspectives are presented with the support of field data

Jet quenching parameter \hat q in the stochastic QCD vacuum with Landau damping

We argue that the radiative energy loss of a parton traversing the quark-gluon plasma is determined by Landau damping of soft modes in the plasma. Using this idea, we calculate the jet quenching parameter of a gluon. The calculation is done in SU(3) quenched QCD within the stochastic vacuum model. At the LHC-relevant temperatures, the result depends on the gluon condensate, the vacuum correlation length, and the gluon Debye mass. Numerically, when the temperature varies from T=T_c to T=900 MeV, the jet quenching parameter rises from \hat q=0 to approximately 1.8 GeV^2/fm. We compare our results with the predictions of perturbative QCD and other calculations.Comment: 20 pages, 6 figures, discussions and references added; final version to appear in Eur. Phys. J.

Strange particle production in proton-proton collisions at s=0.9\sqrt{s}=0.9 TeV with ALICE at the LHC

The production of mesons containing strange quarks (K$^0_s$, $\phi$) and both singly and doubly strange baryons ($\Lambda$, Anti-$\Lambda$, and $\Xi$+Anti-$\Xi$) are measured at central rapidity in pp collisions at $\sqrt{s}$ = 0.9 TeV with the ALICE experiment at the LHC. The results are obtained from the analysis of about 250 k minimum bias events recorded in 2009. Measurements of yields (dN/dy) and transverse momentum spectra at central rapidities for inelastic pp collisions are presented. For mesons, we report yields () of 0.184 $\pm$ 0.002 stat. $\pm$ 0.006 syst. for K$^0_s$ and 0.021 $\pm$ 0.004 stat. $\pm$ 0.003 syst. for $\phi$. For baryons, we find = 0.048 $\pm$ 0.001 stat. $\pm$ 0.004 syst. for $\Lambda$, 0.047 $\pm$ 0.002 stat. $\pm$ 0.005 syst. for Anti-$\Lambda$ and 0.0101 $\pm$ 0.0020 stat. $\pm$ 0.0009 syst. for $\Xi$+Anti-$\Xi$. The results are also compared with predictions for identified particle spectra from QCD-inspired models and provide a baseline for comparisons with both future pp measurements at higher energies and heavy-ion collisions.Comment: 33 pages, 21 captioned figures, 10 tables, authors from page 28, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/387

The SPIRAL radioactive ion beam facility

This document describes the scientific goals as well as the technical choices of the SPIRAL project (Système de Production d'Ions Radioactifs et d'Accélération en Ligne)

Mst4 and Ezrin induce brush borders downstream of the Lkb1/Strad/Mo25 polarization complex.

The human Lkb1 kinase, encoded by the ortholog of the invertebrate Par4 polarity gene, is mutated in Peutz-Jeghers cancer syndrome. Lkb1 activity requires complex formation with the pseudokinase Strad and the adaptor protein Mo25. The complex can induce complete polarization in a single isolated intestinal epithelial cell. We describe an interaction between Mo25alpha and a human serine/threonine kinase termed Mst4. A homologous interaction occurs in the yeast Schizosaccharomyces pombe in the control of polar tip growth. Human Mst4 translocates from the Golgi to the subapical membrane compartment upon activation of Lkb1. Inhibition of Mst4 activity inhibits Lkb1-induced brush border formation, whereas other aspects of polarity such as the formation of lateral junctions remain unaffected. As an essential event in brush border formation, Mst4 phosphorylates the regulatory T567 residue of Ezrin. These data define a brush border induction pathway downstream of the Lkb1/Strad/Mo25 polarization complex, yet separate from other polarity events.

The SPIRAL radioactive ion beam facility

This document describes the scientific goals as well as the technical choices of the SPIRAL project (Système de Production d'Ions Radioactifs et d'Accélération en Ligne)