2,889,907 research outputs found

    High energy density electrochemical cell

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    Primary cell has an anode of lithium, a cathode containing dihaloisocyanuric acid, and a nonaqueous electrolyte comprised of a solution of lithium perchlorate in methyl formate. It produces an energy density of 213 watt hrs/lb and can achieve a high current density

    Probing the density dependence of the symmetry energy by nucleon flow

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    In the framework of the isospin-dependent Boltzmann-Uehling-Uhlenbeck transport model, sensitive regions of some nucleon observables to the nuclear symmetry energy are studied. It is found that the symmetry energy sensitive observable n/p ratio in the 132^{132}Sn+124^{124}Sn reaction at 0.3 GeV/nucleon in fact just probes the density-dependent symmetry energy below the density of 1.5ρ01.5\rho_0 and effectively probes the density-dependent symmetry energy around or somewhat below the saturation density. Nucleon elliptic flow can probe the symmetry energy from the low-density region to the high-density region when changing the incident beam energies from 0.3 to 0.6 GeV/nucleon in the semi-central 132^{132}Sn+124^{124}Sn reaction. And nucleon transverse and elliptic flows in the semi-central 197^{197}Au+197^{197}Au reaction at 0.6 GeV/nucleon are more sensitive to the high-density behavior of the nuclear symmetry energy. One thus concludes that nucleon observables in the heavy reaction system and with higher incident beam energy are more suitable to be used to probe the high-density behavior of the symmetry energy. The present study may help one to get more specific information about the density-dependent symmetry energy from nucleon flow observable in heavy-ion collisions at intermediate energies.Comment: 5 pages, 6 figure

    Effective theory for low-energy nuclear energy density functionals

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    We introduce a new class of effective interactions to be used within the energy-density-functional approaches. They are based on regularized zero-range interactions and constitute a consistent application of the effective-theory methodology to low-energy phenomena in nuclei. They allow for defining the order of expansion in terms of the order of derivatives acting on the finite-range potential. Numerical calculations show a rapid convergence of the expansion and independence of results of the regularization scale.Comment: 5 RevTex pages, 5 figures, misprints corrected, extended version, see also http://iopscience.iop.org/0954-3899/labtalk-article/5109

    Ultralocal energy density in massive gravity

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    We provide a space-time covariant Hamiltonian treatment for a finite-range gravitational theory. The Kuchar approach is used to demonstrate the bimetric picture of space-time in its most transparent form. This Hamiltonian formalism is applied for the straightforward realization of the Poincar\'e algebra in Dirac brackets. It uncovers the simplest form of the Poincar\'e generators expressed as spatial integrals of ultralocal quantities constructed pure algebraically by means of the two space-time metrics.Comment: 17 pages, no figures, LaTe

    Relativistic nuclear energy density functional constrained by low-energy QCD

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    A relativistic nuclear energy density functional is developed, guided by two important features that establish connections with chiral dynamics and the symmetry breaking pattern of low-energy QCD: a) strong scalar and vector fields related to in-medium changes of QCD vacuum condensates; b) the long- and intermediate-range interactions generated by one-and two-pion exchange, derived from in-medium chiral perturbation theory, with explicit inclusion of Δ(1232)\Delta(1232) excitations. Applications are presented for binding energies, radii of proton and neutron distributions and other observables over a wide range of spherical and deformed nuclei from 16O^{16}O to 210Po^{210}Po. Isotopic chains of SnSn and PbPb nuclei are studied as test cases for the isospin dependence of the underlying interactions. The results are at the same level of quantitative comparison with data as the best phenomenological relativistic mean-field models.Comment: 48 pages, 12 figures, elsart.cls class file. Revised version, accepted for publication in Nucl. Phys.

    Energy-momentum Density of Gravitational Waves

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    In this paper, we elaborate the problem of energy-momentum in general relativity by energy-momentum prescriptions theory. Our aim is to calculate energy and momentum densities for the general form of gravitational waves. In this connection, we have extended the previous works by using the prescriptions of Bergmann and Tolman. It is shown that they are finite and reasonable. In addition, using Tolman prescription, exactly, leads to same results that have been obtained by Einstein and Papapetrou prescriptions.Comment: LaTeX, 9 pages, 1 table: added reference

    Dark energy density predicted and explained

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    It has recently been shown that the observed Hubble function for cosmological expansion can be fitted accurately back to redshift unity (7.33 Gyr ago) with only one free constant, while neglecting cosmic curvature and mass, using the modified Friedmann equation implied by subjecting the Higgs scalar field model to conformal Weyl scaling symmetry. Time-dependent solutions of the relativistic conformal Higgs scalar field equation coupled with the conformal Friedmann equation are shown here to imply dark energy of the observed magnitude. Predicted persistent cosmic acceleration is consistent with the nonclassical parameter inferred by conformal theory from observed excessive galactic rotation velocities and galactic dark halos, all without dark matter.Comment: 6 pages MS revised abstract, text, and references. Accepted for Europhysics Letter
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