Roma Tre University

About: Roma Tre University is a education organization based out in Rome, Lazio, Italy. It is known for research contribution in the topics: Large Hadron Collider & Galaxy. The organization has 4434 authors who have published 15352 publications receiving 374888 citations. The organization is also known as: Universita degli Studi Roma Tre & RomaTre.

Aqueous solutions of divalent chlorides: ions hydration shell and water structure.

Abstract: By combining neutron diffraction and Monte Carlo simulations, we have determined the microscopic structure of the hydration ions shell in aqueous solutions of MgCl(2) and CaCl(2), along with the radial distribution functions of the solvent. In particular the hydration shell of the cations, show cation specific symmetry, due to the strong and directional interaction of ions and water oxygens. The ions and their hydration shells likely form molecular moieties and bring clear signatures in the water-water radial distribution functions. Apart from these signatures, the influence of divalent salts on the microscopic structure of water is similar to that of previously investigated monovalent solutes, and it is visible as a shift of the second peak of the oxygen-oxygen radial distribution function, caused by distortion of the hydrogen bond network of water.

Non-equilibrium thermodynamics of piecewise deterministic markov processes

Abstract: We consider a class of stochastic dynamical systems, called piecewise deterministic Markov processes, with states (x,σ)∈Ω×Γ, Ω being a region in ℝ d or the d-dimensional torus, Γ being a finite set. The continuous variable x follows a piecewise deterministic dynamics, the discrete variable σ evolves by a stochastic jump dynamics and the two resulting evolutions are fully-coupled. We study stationarity, reversibility and time-reversal symmetries of the process. Increasing the frequency of the σ-jumps, the system behaves asymptotically as deterministic and we investigate the structure of its fluctuations (i.e. deviations from the asymptotic behavior), recovering in a non Markovian frame results obtained by Bertini et al. (Phys. Rev. Lett. 87(4):040601, 2001; J. Stat. Phys. 107(3–4):635–675, 2002; J. Stat. Mech. P07014, 2007; Preprint available online at http://www.arxiv.org/abs/0807.4457 , 2008), in the context of Markovian stochastic interacting particle systems. Finally, we discuss a Gallavotti–Cohen-type symmetry relation with involution map different from time-reversal.

Glauber Dynamics on Trees: Boundary Conditions and Mixing Time

Abstract: We give the first comprehensive analysis of the effect of boundary conditions on the mixing time of the Glauber dynamics in the so-called Bethe approximation Specifically, we show that the spectral gap and the log-Sobolev constant of the Glauber dynamics for the Ising model on an n-vertex regular tree with (+)-boundary are bounded below by a constant independent of n at all temperatures and all external fields This implies that the mixing time is O(logn) (in contrast to the free boundary case, where it is not bounded by any fixed polynomial at low temperatures) In addition, our methods yield simpler proofs and stronger results for the spectral gap and log-Sobolev constant in the regime where the mixing time is insensitive to the boundary condition Our techniques also apply to a much wider class of models, including those with hard-core constraints like the antiferromagnetic Potts model at zero temperature (proper colorings) and the hard–core lattice gas (independent sets)

Characterization of pABVA01, a plasmid encoding the OXA-24 carbapenemase from Italian isolates of Acinetobacter baumannii

Abstract: Two epidemiologically unrelated carbapenem-resistant Acinetobacter baumannii isolates were investigated as representatives of the first Italian isolates producing the OXA-24 carbapenemase. Both isolates were of European clonal lineage II and carried an identical OXA-24-encoding plasmid, named pABVA01. Comparative analysis revealed that in pABVA01, bla(OXA-24) was part of a DNA module flanked by conserved inverted repeats homologous to XerC/XerD binding sites, which in other Acinetobacter plasmids flank different DNA modules, suggesting mobilization by a novel site-specific recombination mechanism.