Alpha-particle clustering in excited expanding self-conjugate nuclei

The fragmentation of quasi-projectiles from the nuclear reaction 40Ca + 12C at 25 MeV/nucleon was used to produce alpha-emission sources. From a careful selection of these sources provided by a complete detection and from comparisons with models of sequential and simultaneous decays, strong indications in favour of $\alpha$-particle clustering in excited 16O, 20Ne and 24}Mg are reported.Comment: 8 pages, 4 figures, 12th International Conference on Nucleus-Nucleus collisions (NN2015), 21-26 June 2015, Catania, Ital

Equidistribution Rates, Closed String Amplitudes, and the Riemann Hypothesis

We study asymptotic relations connecting unipotent averages of $Sp(2g,\mathbb{Z})$ automorphic forms to their integrals over the moduli space of principally polarized abelian varieties. We obtain reformulations of the Riemann hypothesis as a class of problems concerning the computation of the equidistribution convergence rate in those asymptotic relations. We discuss applications of our results to closed string amplitudes. Remarkably, the Riemann hypothesis can be rephrased in terms of ultraviolet relations occurring in perturbative closed string theory.Comment: 15 page

CONTROLLO GLICOMETABOLICO E ABITUDINI ALIMENTARI IN ADOLESCENTI CON DIABETE MELLITO TIPO 1

Background: Gli studi che hanno valutato le abitudini alimentari dei bambini e adolescenti con diabete, hanno riportato una percentuale di assunzione di carboidrati più bassa di quella minima raccomandata spesso associata ad un maggiore consumo di grassi e ad una ridotta assunzione di fibre . Alcuni studi che hanno valutato il rapporto tra composizione della dieta e controllo glicometabolico in soggetti con diabete tipo 1, hanno evidenziato che una dieta ricca di grassi e povera di fibre è associata ad un peggior controllo glicometabolico. Obiettivo: Valutare in adolescenti affetti da diabete mellito tipo 1, con diverso grado di controllo metabolico, la frequenza di consumo settimanale dei vari gruppi di alimenti e l’eventuale correlazione di questa con i valori di emoglobina glicosilata ( HbA1c). Metodo: In 43 soggetti (M/F :22/21; età 11-14 anni) suddivisi in due gruppi in rapporto al valore mediano di HbA1c ( 8,45%), sono stati raccolti i dati relativi ai consumi alimentari degli ultimi tre mesi attraverso un questionario di frequenza di consumo ed è stata considerata la frequenza di scelte alimentari settimanali per gruppo di alimenti. Risultati I soggetti con miglior controllo glicometabolico (HbA1c< 8,45%) presentavano una maggiore frequenza di consumo settimanale dei seguenti gruppi di alimenti: frutta( p<0,0001) , ortaggi (p=0,017) e legumi ( p=0,03). I soggetti con peggior controllo glicometabolico ( HbA1c > 8,45%) consumavano con maggiore frequenza alimenti appartenenti al gruppo di salumi (p=0,007), formaggi (p=0,02) e dolci /bevande zuccherate (p=0,0065). I valori di HbA1c erano inversamente correlati alla frequenza di consumo settimanale di frutta ((r – 0,65 p< 0,0001) e a quello di ortaggi( r – 0,32 p < 0,017) e direttamente correlati alla frequenza settimanale di consumo di alimenti appartenenti ai gruppi di salumi ( r 0,37 p< 0,007). Conclusioni: Il controllo glicometabolico in adolescenti con diabete tipo 1 è influenzato dalla frequenza di consumo settimanale di alimenti ricchi di fibre e di grassi animali. I principi di una san

Noncommutative Symmetries and Gravity

Spacetime geometry is twisted (deformed) into noncommutative spacetime geometry, where functions and tensors are now star-multiplied. Consistently, spacetime diffeomorhisms are twisted into noncommutative diffeomorphisms. Their deformed Lie algebra structure and that of infinitesimal Poincare' transformations is defined and explicitly constructed. This allows to construct a noncommutative theory of gravity.Comment: 26 pages. Lectures given at the workshop `Noncommutative Geometry in Field and String Theories', Corfu Summer Institute on EPP, September 2005, Corfu, Greece. Version 2: Marie Curie European Reintegration Grant MERG-CT-2004-006374 acknowledge

Production of α\alpha-particle condensate states in heavy-ion collisions

The fragmentation of quasi-projectiles from the nuclear reaction $^{40}Ca$ + $^{12}C$ at 25 MeV/nucleon was used to produce excited states candidates to $\alpha$-particle condensation. The experiment was performed at LNS-Catania using the CHIMERA multidetector. Accepting the emission simultaneity and equality among the $\alpha$-particle kinetic energies as experimental criteria for deciding in favor of the condensate nature of an excited state, we analyze the $0_2^+$ and $2_2^+$ states of $^{12}$C and the $0_6^+$ state of $^{16}$O. A sub-class of events corresponding to the direct 3-$\alpha$ decay of the Hoyle state is isolated.Comment: contribution to the 2nd Workshop on "State of the Art in Nuclear Cluster Physics" (SOTANCP2), Universite Libre de Bruxelles (Belgium), May 25-28, 2010, to be published in the International Journal of Modern Physics

Chaotic Scattering in Heavy--Ion Reactions

We discuss the relevance of chaotic scattering in heavy--ion reactions at energies around the Coulomb barrier. A model in two and three dimensions which takes into account rotational degrees of freedom is discussed both classically and quantum-mechanically. The typical chaotic features found in this description of heavy-ion collisions are connected with the anomalous behaviour of several experimental data.Comment: 35 pages in RevTex (version 3.0) plus 27 PostScript figures obtainable by anonymous ftp from VAXFCT.CT.INFN.IT in directory kaos. Fig. 1 upon request to the authors. To be published in the October Focus issue on chaotic scattering of CHAO

Noncommutative Self-dual Gravity

Starting from a self-dual formulation of gravity, we obtain a noncommutative theory of pure Einstein theory in four dimensions. In order to do that, we use Seiberg-Witten map. It is shown that the noncommutative torsion constraint is solved by the vanishing of commutative torsion. Finally, the noncommutative corrections to the action are computed up to second order.Comment: 15+1 pages, LaTeX, no figure

Freeze-out configuration properties in the 197Au + 197Au reaction at 23 AMeV

Data from the experiment on the 197Au + 197Au reaction at 23 AMeV are analyzed with an aim to find signatures of exotic nuclear configurations such as toroid-shaped objects. The experimental data are compared with predictions of the ETNA code dedicated to look for such configurations and with the QMD model. A novel criterion of selecting events possibly resulting from the formation of exotic freeze-out configurations, "the efficiency factor", is tested. Comparison between experimental data and model predictions may indicate for the formation of flat/toroidal nuclear systems

Multifragmentation threshold in ^{93}Nb+{nat}Mg collisions at 30 MeV/nucleon

We analyzed the $^{93}Nb$ on $^{nat}Mg$ reaction at 30 MeV/nucleon in the aim of disentangling binary sequential decay and multifragmentation decay close to the energy threshold, i.e. $\simeq 3$ MeV/nucleon. Using the backtracing technique applied to the statistical models GEMINI and SMM we reconstruct simulated charge, mass and excitation energy distributions and compare them to the experimental ones. We show that data are better described by SMM than by GEMINI in agreement with the fact that multifragmentation is responsible for fragment production at excitation energies around 3 MeV/nucleon.Comment: 16 pages, 12 figures, 5 tables Soumis \`a Nuclear Physics