Halogen (F, Cl, Br, and I) Devolatilization During Prograde Subduction: Insights From Western Alps Ophiolites

In order to examine the progressive chemical evolution of halogens (F, Cl, Br, I) in altered ocean crust (AOC) during prograde subduction, this study compares bulk and in situ halogen concentrations in mafic samples from three petrogenetically related exhumed terrains in the Western Alps (the Chenaillet ophiolite, the Queyras ophiolites of the Schistes Lustrés, and the Monviso ophiolite). Samples from the Chenaillet ophiolite represent oceanic crust unaffected by metamorphic halogen loss and define a protolith halogen content (122 μg/g F, 29 μg/g Cl, 82 ng/g Br, and 98 ng/g I). Samples from the Queyras ophiolites experienced blueschist facies conditions, undergoing recrystallization and halogen loss (74 μg/g F, 19 μg/g Cl, 70 ng/g Br, and 63 ng/g I). Eclogite facies samples from the Monviso meta-ophiolite exhibit markedly reduced Cl (8 μg/g Cl) and Br (42 ng/g Br) contents relative to samples from Chenaillet and Queyras. Using electron probe microanalysis (EPMA), F and Cl host minerals (e.g., amphibole, chlorite, epidote) are identified and characterized in selected samples, showing a broad distribution of F and Cl, lending support to the view that halogen devolatilization in the subducting slab occurs continuously and is not dependent on the breakdown of a particular phase. In situ Cl concentrations decrease significantly between sub-greenschist and blueschist assemblages. Fluorine is retained within subducting AOC and is decoupled from the heavy halogens (Cl, Br, I), which undergo continuous devolatilization during prograde metamorphism

Quantum ESPRESSO: One Further Step toward the Exascale

We review the status of the Quantum ESPRESSO software suite for electronic-structure calculations based on plane waves, pseudopotentials, and density-functional theory. We highlight the recent developments in the porting to GPUs of the main codes, using an approach based on OpenACC and CUDA Fortran offloading. We describe, in particular, the results achieved on linear-response codes, which are one of the distinctive features of the Quantum ESPRESSO suite. We also present extensive performance benchmarks on different GPU-accelerated architectures for the main codes of the suite

Structure and dynamics of ring polymers: entanglement effects because of solution density and ring topology

The effects of entanglement in solutions and melts of unknotted ring polymers have been addressed by several theoretical and numerical studies. The system properties have been typically profiled as a function of ring contour length at fixed solution density. Here, we use a different approach to investigate numerically the equilibrium and kinetic properties of solutions of model ring polymers. Specifically, the ring contour length is maintained fixed, while the interplay of inter- and intra-chain entanglement is modulated by varying both solution density (from infinite dilution up to \approx 40 % volume occupancy) and ring topology (by considering unknotted and trefoil-knotted chains). The equilibrium metric properties of rings with either topology are found to be only weakly affected by the increase of solution density. Even at the highest density, the average ring size, shape anisotropy and length of the knotted region differ at most by 40% from those of isolated rings. Conversely, kinetics are strongly affected by the degree of inter-chain entanglement: for both unknots and trefoils the characteristic times of ring size relaxation, reorientation and diffusion change by one order of magnitude across the considered range of concentrations. Yet, significant topology-dependent differences in kinetics are observed only for very dilute solutions (much below the ring overlap threshold). For knotted rings, the slowest kinetic process is found to correspond to the diffusion of the knotted region along the ring backbone.Comment: 17 pages, 11 figure

baseline predictive factors for efficacy of anti pd1 used in first line in melanoma patients an italian melanoma intergroup study

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Meson exchange and nucleon polarizabilities in the quark model

Modifications to the nucleon electric polarizability induced by pion and sigma exchange in the q-q potentials are studied by means of sum rule techniques within a non-relativistic quark model. Contributions from meson exchange interactions are found to be small and in general reduce the quark core polarizability for a number of hybrid and one-boson-exchange q-q models. These results can be explained by the constraints that the baryonic spectrum impose on the short range behavior of the mesonic interactions.Comment: 11 pages, 1 figure added, expanded discussio

Magnetic Fields of Accreting X-Ray Pulsars with the Rossi X-Ray Timing Explorer

Using a consistent set of models, we parameterized the X-ray spectra of all accreting pulsars in the Rossi X-ray Timing Explorer database which exhibit Cyclotron Resonance Scattering Features (CRSFs, or cyclotron lines). These sources in our sample are Her X-1, 4U 0115+63, Cen X-3, 4U 1626-67, XTE J1946-274, Vela X-1, 4U 1907+09, 4U 1538-52, GX 301-2, and 4U 0352+309 (X Per). We searched for correlations among the spectral parameters, concentrating on how the cyclotron line energy relates to the continuum and therefore how the neutron star B-field influences the X-Ray emission. As expected, we found a correlation between the CRSF energy and the spectral cutoff energy. However, with our consistent set of fits we found that the relationship is more complex than what has been reported previously. Also, we found that not only does the width of the cyclotron line correlate with the energy (as suggested by theory), but that the width scaled by the energy correlates with the depth of the feature. We discuss the implications of these results, including the possibility that accretion directly affects the relative alignment of the neutron star spin and dipole axes. Lastly, we comment on the current state of fitting phenomenological models to spectra in the RXTE/BeppoSAX era and the need for better theoretical models of the X-Ray continua of accreting pulsars.Comment: 36 Pages, 9 Figures, 9 Tables, ApJ in pres

Lattice Boltzmann Simulations of Liquid Crystal Hydrodynamics

We describe a lattice Boltzmann algorithm to simulate liquid crystal hydrodynamics. The equations of motion are written in terms of a tensor order parameter. This allows both the isotropic and the nematic phases to be considered. Backflow effects and the hydrodynamics of topological defects are naturally included in the simulations, as are viscoelastic properties such as shear-thinning and shear-banding.Comment: 14 pages, 5 figures, Revte

The Lorentz Integral Transform (LIT) method and its applications to perturbation induced reactions

The LIT method has allowed ab initio calculations of electroweak cross sections in light nuclear systems. This review presents a description of the method from both a general and a more technical point of view, as well as a summary of the results obtained by its application. The remarkable features of the LIT approach, which make it particularly efficient in dealing with a general reaction involving continuum states, are underlined. Emphasis is given on the results obtained for electroweak cross sections of few--nucleon systems. Their implications for the present understanding of microscopic nuclear dynamics are discussed.Comment: 83 pages, 31 figures. Topical review. Corrected typo

Spinodal decomposition of off-critical quenches with a viscous phase using dissipative particle dynamics in two and three spatial dimensions

We investigate the domain growth and phase separation of hydrodynamically-correct binary immiscible fluids of differing viscosity as a function of minority phase concentration in both two and three spatial dimensions using dissipative particle dynamics. We also examine the behavior of equal-viscosity fluids and compare our results to similar lattice-gas simulations in two dimensions.Comment: 34 pages (11 figures); accepted for publication in Phys. Rev.