15,786 research outputs found

    Continuum time-dependent Hartree-Fock for giant resonances in spherical nuclei

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    This paper deals with the solution of the spherically symmetric time-dependent Hartree-Fock approximation applied in the case of nuclear giant monopole resonances. The problem is spatially unbounded as the resonance state is in the continuum. The practical requirement to perform the calculation in a finite-sized spatial region results in a difficulty with the spatial boundary conditions. Here we propose a absorbing boundary condition scheme to handle the conflict. The derivation, via a Laplace transform method, and implementation is described. The accuracy and efficiency of the scheme is tested and the results presented to support the case that they are a effective way of handling the artificial boundary.Comment: 13 pages, 8 figure

    Morita theory and singularity categories

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    We propose an analogue of the bounded derived category for an augmented ring spectrum, defined in terms of a notion of Noether normalization. In many cases we show this category is independent of the chosen normalization. Based on this, we define the singularity and cosingularity categories measuring the failure of regularity and coregularity and prove they are Koszul dual in the style of the BGG correspondence. Examples of interest include Koszul algebras and Ginzburg DG-algebras, C∗(BG)C^*(BG) for finite groups (or for compact Lie groups with orientable adjoint representation), cochains in rational homotopy theory and various examples from chromatic homotopy theory.Comment: Final version, accepted for publication in Advances in Mathematics, 49 page

    Low-Energy Heavy-Ion Reactions and the Skyrme Effective Interaction

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    The Skyrme effective interaction, with its multitude of parameterisations, along with its implemen- tation using the static and time-dependent density functional (TDHF) formalism have allowed for a range of microscopic calculations of low-energy heavy-ion collisions. These calculations allow variation of the effective interaction along with an interpretation of the results of this variation informed by a comparison to experimental data. Initial progress in implementing TDHF for heavy-ion collisions necessarily used many approximations in the geometry or the interaction. Over the last decade or so, the implementations have overcome all restrictions, and studies have begun to be made where details of the effective interaction are being probed. This review surveys these studies in low energy heavy-ion reactions, finding significant effects on observables from the form of the spin-orbit interaction, the use of the tensor force, and the inclusion of time-odd terms in the density functional.Comment: submitted to Prog. Part. Nucl. Phy

    Challenging the orthodoxy: union learning representatives as organic intellectuals

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    Teacher education and continuing professional development have become a key areas of controversy in England since the period of school sector restructuring following the 1988 Education Reform Act. More recently teacher training and professional development have often been used to promote and reinforce a narrow focus on the government’s ‘standards agenda’. However, the emerging discourse of ‘new professionalism’ has raised the profile of professional development in schools, and together with union learning representatives, there are opportunities to secure real improvements in teachers’ access to continuing professional development. This paper argues however that union learning representatives must go beyond advocating for better access to professional development and should raise more fundamental questions about the nature of professional development and the education system it serves. Drawing on Gramsci’s notion of the ‘organic intellectual’, the paper argues that union learning representatives have a key role as organisers of ideas – creating spaces in which the ideological dominance of current policy orthodoxy might be challenged

    Density distributions of superheavy nuclei

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    We employed the Skyrme-Hartree-Fock model to investigate the density distributions and their dependence on nuclear shapes and isospins in the superheavy mass region. Different Skyrme forces were used for the calculations with a special comparison to the experimental data in 208^{208}Pb. The ground-state deformations, nuclear radii, neutron skin thicknesses and α\alpha-decay energies were also calculated. Density distributions were discussed with the calculations of single-particle wavefunctions and shell fillings. Calculations show that deformations have considerable effects on the density distributions, with a detailed discussion on the 292^{292}120 nucleus. Earlier predictions of remarkably low central density are not supported when deformation is allowed for.Comment: 7 pages, 10 figure
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