1,362 research outputs found

    Community-linked maternal death review (CLMDR) to measure and prevent maternal mortality: a pilot study in rural Malawi.

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    In Malawi, maternal mortality remains high. Existing maternal death reviews fail to adequately review most deaths, or capture those that occur outside the health system. We assessed the value of community involvement to improve capture and response to community maternal deaths

    Isospin diffusion in semi-peripheral 58Ni^{58}Ni + 197Au^{197}Au collisions at intermediate energies (I): Experimental results

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    Isospin diffusion in semi-peripheral collisions is probed as a function of the dissipated energy by studying two systems 58Ni^{58}Ni + 58Ni^{58}Ni and 58Ni^{58}Ni + 197Au^{197}Au, over the incident energy range 52-74\AM. A close examination of the multiplicities of light products in the forward part of phase space clearly shows an influence of the isospin of the target on the neutron richness of these products. A progressive isospin diffusion is observed when collisions become more central, in connection with the interaction time

    Angle of Repose and Angle of Marginal Stability: Molecular Dyanmics of Granular Particles

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    We present an implementation of realistic static friction in molecular dynamics (MD) simulations of granular particles. In our model, to break contacts between two particles, one has to apply a finite amount of force, determined by the Coulomb criterion. Using a two dimensional model, we show that piles generated by avalanches have a {\it finite} angle of repose θR\theta_R (finite slopes). Furthermore, these piles are stable under tilting by an angle smaller than a non-zero tilting angle θT\theta_T, showing that θR\theta_R is different from the angle of marginal stability θMS\theta_{MS}, which is the maximum angle of stable piles. These measured angles are compared to a theoretical approximation. We also measure θMS\theta_{MS} by continuously adding particles on the top of a stable pile.Comment: 14 pages, Plain Te

    Free-volume kinetic models of granular matter

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    We show that the main dynamical features of granular media can be understood by means of simple models of fragile-glass forming liquid provided that gravity alone is taken into account. In such lattice-gas models of cohesionless and frictionless particles, the compaction and segregation phenomena appear as purely non-equilibrium effects unrelated to the Boltzmann-Gibbs measure which in this case is trivial. They provide a natural framework in which slow relaxation phenomena in granular and glassy systems can be explained in terms of a common microscopic mechanism given by a free-volume kinetic constraint.Comment: 4 pages, 6 figure

    Isospin Diffusion in 58^{58}Ni-Induced Reactions at Intermediate Energies

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    Isospin diffusion is probed as a function of the dissipated energy by studying two systems 58^{58}Ni+58^{58}Ni and 58^{58}Ni+197^{197}Au, over the incident energy range 52-74\AM. Experimental data are compared with the results of a microscopic transport model with two different parameterizations of the symmetry energy term. A better overall agreement between data and simulations is obtained when using a symmetry term with a potential part linearly increasing with nuclear density. The isospin equilibration time at 52 \AM{} is estimated to 130±\pm10 fm/cc

    The prominent role of the heaviest fragment in multifragmentation and phase transition for hot nuclei

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    The role played by the heaviest fragment in partitions of multifragmenting hot nuclei is emphasized. Its size/charge distribution (mean value, fluctuations and shape) gives information on properties of fragmenting nuclei and on the associated phase transition.Comment: 11 pages, Proceedings of IWND09, August 23-25, Shanghai (China

    Status and performances of the FAZIA project

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    FAZIA is designed for detailed studies of the isospin degree of freedom, extending to the limits the isotopic identification of charged products from nuclear collisions when using silicon detectors and CsI(Tl) scintillators. We show that the FAZIA telescopes give isotopic identification up to Z\sim25 with a Δ\DeltaE-E technique. Digital Pulse Shape Analysis makes possible elemental identification up to Z=55 and isotopic identification for Z=1-10 when using the response of a single silicon detector. The project is now in the phase of building a demonstrator comprising about 200 telescopes

    Nuclear multifragmentation time-scale and fluctuations of largest fragment size

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    Distributions of the largest fragment charge, Zmax, in multifragmentation reactions around the Fermi energy can be decomposed into a sum of a Gaussian and a Gumbel distribution, whereas at much higher or lower energies one or the other distribution is asymptotically dominant. We demonstrate the same generic behavior for the largest cluster size in critical aggregation models for small systems, in or out of equilibrium, around the critical point. By analogy with the time-dependent irreversible aggregation model, we infer that Zmax distributions are characteristic of the multifragmentation time-scale, which is largely determined by the onset of radial expansion in this energy range.Comment: Accepted for publication in Physical Review Letters on 8/4/201

    Dynamical effects in multifragmentation at intermediate energies

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    The fragmentation of the quasi-projectile is studied with the INDRA multidetector for different colliding systems and incident energies in the Fermi energy range. Different experimental observations show that a large part of the fragmentation is not compatible with the statistical fragmentation of a fully equilibrated nucleus. The study of internal correlations is a powerful tool, especially to evidence entrance channel effects. These effects have to be included in the theoretical descriptions of nuclear multifragmentation.Comment: 13 pages, 26 figures, submitted to Physical Review
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