Dynamical fragment production in central collisions Xe(50 A.MeV)+Sn

For central collisions Xe(50 A.MeV)+Sn we compared experimental data from the INDRA detector with QMD simulations. Theory as well as experiment show a clear binary character of the fragment emission even for very central collisions. From the time evolution of the reaction (QMD simulation) we could built up a scenario for the dynamical emission of fragmentsComment: To appear in the Proceedings of the 36th International Winter Meeting on Nuclear Physics, Bormio, Italy, Jan. 26-31 199

On the origin of the radial flow in low energy heavy ion reactions

The average transverse energy of nucleons and intermediate mass fragments observed in the heavy ion reaction Xe(50A MeV)+Sn shows the same linear increase as a function of their mass as observed in heavy ion collisions up to the highest ene rgies available today and fits well into the systematics. At higher energies this observation has been interpreted as a sign of a strong radial flow in an otherwise thermalized system. Investigating the reaction with Quantum Molecular dynamics simulations we find in between 50A MeV and 200A MeV a change in the reaction mechanism. At 50A MeV the apparent radial flow is merely caused by an in-plane flow and Coulomb repulsion. The average transverse fragment energy does not change in the course of the reaction and is equal to the initial fragment energy due to the Fermi motion. At 200A MeV, there are two kinds of fragments: those formed from spectator matte r and those from the center of the reaction. There the transverse energy is caused by the pr essure from the compressed nuclear matter. In both cases we observe a binary event stru cture, even in central collisions. This demonstrates as well the non thermal character of the reaction. The actual process which leads to multifragmentation is rather complex and is discussed in detail.Comment: 12 pages, 9 figures, revised version (submitted to NPA

Arabidopsis ILITHYIA protein is necessary for proper chloroplast biogenesis and root development independent of eIF2alpha phosphorylation

[EN] One of the main mechanisms blocking translation after stress situations is mediated by phosphorylation of the alpha-subunit of the eukaryotic initiation factor 2 (eIF2), performed in Arabidopsis by the protein kinase GCN2 which interacts and is activated by ILITHYIA(ILA). ILA is involved in plant immunity and its mutant lines present phenotypes not shared by the gcn2 mutants. The functional link between these two genes remains elusive in plants. In this study, we show that, although both ILA and GCN2 genes are necessary to mediate eIF2 alpha phosphorylation upon treatments with the aromatic amino acid biosynthesis inhibitor glyphosate, their mutants develop distinct root and chloroplast phenotypes. Electron microscopy experiments reveal that ila mutants, but not gcn2, are affected in chloroplast biogenesis, explaining the macroscopic phenotype previously observed for these mutants. ila3 mutants present a complex transcriptional reprogramming affecting defense responses, photosynthesis and protein folding, among others. Double mutant analyses suggest that ILA has a distinct function which is independent of GCN2 and eIF2 alpha phosphorylation. These results suggest that these two genes may have common but also distinct functions in Arabidopsis.Microarray experiments were done in the Genomics Facility of the IBMCP. MTH was supported by the Austrian Science Found (FWF) projectF03707. This work has been supported by the Spanish Ministry for Science and Education (Plan Nacional 2008-2011).Faus, I.; Niñoles Rodenes, R.; Kesari, V.; Llabata, P.; Tam, E.; Nebauer, SG.; Santiago, J.... (2018). Arabidopsis ILITHYIA protein is necessary for proper chloroplast biogenesis and root development independent of eIF2alpha phosphorylation. Journal of Plant Physiology. 224:173-182. https://doi.org/10.1016/j.jplph.2018.04.003S17318222

LES PROPRIETES DES QUARKS ET MESONS A DENSITE ET TEMPERATURE FINIES DANS LE CADRE DU MODELE NJL

LE MODELE DE NAMBU ET JONA-LASINIO (NJL) DOIT ETRE LA BASE POUR LA SIMULATION DE L'EXPANSION ET HADRONISATION D'UN PLASMA DE QUARKS. LE POINT FORT DU MODELE NJL ETANT L'IMPLEMENTATION EXACTE DE LA SYMETRIE CHIRALE ET DE SA BRISURE SPONTANEE, LE POINT FAIBLE EST LE CONFINEMENT. COMME LA PLUPART DES MODELES EFFECTIVES, LE MODELE NJL NE DECRIT PAS LE CONFINEMENT. LES AVANTAGES ET DESAVANTAGES DU MODELE NJL EN ETANT UNE APPROXIMATION DE QCD A BASSE ENERGIE SERONT DISCUTE EN DETAIL AU COURS DE L'EXPOSE AFIN DE BIEN DETERMINER LES POSSIBILITES MAIS AUSSI LES LIMITES DU MODELE. DANS LE CADRE DE CETTE THESE UNE ETUDE DETAILLEE DES PROPRIETES THERMODYNAMIQUE DU MODELE NJL A ETE ELABORE. LA CONNAISSANCE PROFONDE DES PROPRIETES D'UN SYSTEME EN EQUILIBRE EST INDISPENSABLE AVANT PASSER AUX SYSTEMES HORS EQUILIBRE, COMME PAR EXEMPLE UN PLASMA EN EXPANSION. LA TRANSITION DE PHASE LA PLUS IMPORTANTE DANS LE CAS D'UN PLASMA DE QUARK, EST LA TRANSITION DE PHASE CHIRALE. UN AUTRE PROCESSUS IMPORTANT EST LA HADRONISATION. AFIN D'ETUDIER LES PHENOMENES LIES AUX TRANSITIONS DE PHASES, LA CONNAISSANCE DU DIAGRAMME DES PHASES ET DES PROPRIETES DES HADRONS DANS LE MILIEU EST INDISPENSABLE. LE MODELE NJL A L'AVANTAGE DE PERMETTRE DES CALCULS A DENSITE ET TEMPERATURE FINIES. DES COMPARAISONS AVEC DES CALCULS QCD SUR RESEAUX MONTRENT, QUE LE MODELE NJL DECRIT CORRECTEMENT LA BRISURE ET LA RESTAURATION DE LA SYMETRIE CHIRALE. NOUS ALLONS PRESENTER UN DIAGRAMME DES PHASES DU MODELE NJL A TROIS SAVEURS. LA DEPENDANCE DES PARAMETRES DE CE DIAGRAMME DES PHASES SERA DISCUTER AFIN DE COMPLETER CETTE ETUDE ET DE DETERMINER LA FIABILITE DES RESULTATS. NOUS NOUS INTERESSONS AUSSI AU PROPRIETES DES MESONS A TEMPERATURE ET DENSITE FINIE DANS LE CADRE DU MODELE NJL. NOUS AVONS PLUS SPECIALEMENT ETUDIE ET COMPARER LES RESULTATS DES DIFFERENTES VERSIONS DU MODELE NJL AFIN DE TROUVER LA VERSION LA PLUS ADAPTEE A NOTRE PROBLEME ET EN MEME TEMPS LA PLUS REALISTE DANS CETTE DOMAINE. POUR CELA NOUS AVONS COMPARE PAR EXEMPLE LA MASSE DES KAONS DANS UN MILIEU CHAUD ET DENSE AVEC DES DONNEES DES EXPERIENCES AU GSI ET AVEC AUTRES APPROCHES COMME RMF ET CHPT. UN DERNIER POINT QUI SERA EVOQUE DANS CETTE THESE EST LA ZONE DE BASSE TEMPERATURE ET HAUTE DENSITE DANS LE DIAGRAMME DES PHASES. DANS CETTE REGION LA FORMATION D'UN CONDENSAT DE DIQUARKS EST ATTENDUE. CE CONDENSAT EST RESPONSABLE POUR LA SUPRACONDUCTIVITE DE COULEURS. MEME SI CETTE ZONE N'EST PAS SPECIALEMENT D'INTERET POUR LES COLLISIONS D'IONS LOURDS, IL Y A DES APPLICATIONS DANS L'ASTROPHYSIQUE. ENSEMBLE AVEC LA MATIERE ETRANGE, QUI EST DISCUTE BRIEVEMENT DANS CETTE THESE, LA SUPRACONDUCTIVITE DE COULEURS FAIT UNE SORTE D'INTERFACE ENTRE LA PHYSIQUE DES COLLISIONS D'IONS LOURDS ET L'ASTROPHYSIQUE.NANTES-BU Sciences (441092104) / SudocSudocFranceF