1,596 research outputs found

    Thomas-Fermi approximation to static vortex states in superfluid trapped atomic gases

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    We revise the Thomas-Fermi approximation for describing vortex states in Bose condensates of magnetically trapped atoms. Our approach is based on considering the hbar -> 0 limit rather than the N -> infinity limit as Thomas-Fermi approximation in close analogy with the Fermi systems. Even for relatively small numbers of trapped particles we find good agreement between Gross-Pitaevskii and Thomas-Fermi calculations for the different contributions to the total energy of the atoms in the condensate. We also discuss the application of our approach to the description of vortex states in superfluid fermionic systems in the Ginzburg-Landau regime.Comment: 11 pages, 6 figures, revtex4, substantially revised versio

    Semi-Classical Description of the Average Pairing Properties in Nuclei

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    We present a new semi-classical theory for describing pairing in finite Fermi systems. It is based in taking the ℏ→0\hbar \to 0, i.e. Thomas-Fermi, limit of the gap equation written in the basis of the mean field (weak coupling). In addition to the position dependence of the Fermi momentum, the size dependence of the matrix elements of the pairing force is also taken into account in this theory. An example typical for the nuclear situation shows the improvement of this new approach over the standard Local Density Approximation. We also show that if in this approach some shell fluctuations are introduced in the level density, the arch structure displayed by the quantal gaps along isotopic chains is almost recovered. We also point out that in heavy drip line nuclei pairing is strongly reduced

    Playing Out: A Movement for Movement?

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    In 2009, the “Playing Out” project was set up in Bristol in the United Kingdom by a parent-led community group who were seeking to address concerns about the lack of freedom for young people to play outside. Playing Out has, as its primary purpose, supporting children to “play out” where they live through providing the space within which children might engage in informal play and physical activity, while also improving relations between neighbors and developing a sense of community. This paper examines the potential of Playing Out for fostering community cohesion by undertaking interviews with participants, officials and policy-makers, alongside some observation of Playing Out events, between 2013 and 2016. In particular, we evaluate the significance of social capital for the development, and success, of a community-led initiative to influence policy outcomes and increase physical activity levels in the local population, giving consideration to the ways in which social movement concepts build on, and strengthen, social capital. In many societies, such activities take place within a context of neoliberalism, where social order is viewed as being dependent on individual responsibility: governments are deregulated, social programs are cut and/or privatized, and social problems have to be solved by individual, private solutions. Our findings draw on the work of Putnam (1993, 1996, 2000) to demonstrate that social capital is both cause and effect in the success of initiatives such as Playing Out, and that when social capital is combined with elements of a social movement, there can be more fundamental and sustained outcomes.Peer reviewedFinal Published versio

    Fast and optimal solution to the Rankine-Hugoniot problem

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    A new, definitive, reliable and fast iterative method is described for determining the geometrical properties of a shock (i.e., theta sub Bn, yields N, V sub s and M sub A), the conservation constants and the self-consistent asymptotic magnetofluid variables, that uses the three dimensional magnetic field and plasma observations. The method is well conditioned and reliable at all theta sub Bn angles regardless of the shock strength or geometry. Explicit proof of uniqueness of the shock geometry solution by either analytical or graphical methods is given. The method is applied to synthetic and real shocks, including a bow shock event and the results are then compared with those determined by preaveraging methods and other iterative schemes. A complete analysis of the confidence region and error bounds of the solution is also presented

    The inner edge of the plasma sheet and the diffuse aurora

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    Three dimensional measurements from the ISEE-1 low energy electron spectrometer are used to map the location of the inner edge of the plasma sheet and study the anisotropies in the electron distribution function associated with this boundary. Lower energy plasma sheet electrons have inner edges closer to the Earth than higher energies with the separations at different energies being larger near dawn and after dusk than at midnight. Lowest energy inner edges are frequently located adjacent to the plasmapause in the dawn hemisphere but are often separated from it in the dusk hemisphere by a gap of at least several Re. The energy dispersion is minimal in the afternoon quadrant where the inner edge is near the magnetopause and frequently oscillating on a time scale of minutes. The location of the inner edge is probably determined primarily by the motion of electrons in the existing electric and magnetic fields rather than by strong diffusion as has sometimes been supposed

    Theoretical study of elastic electron scattering off stable and exotic nuclei

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    Results for elastic electron scattering by nuclei, calculated with charge densities of Skyrme forces and covariant effective Lagrangians that accurately describe nuclear ground states, are compared against experiment in stable isotopes. Dirac partial-wave calculations are performed with an adapted version of the ELSEPA package. Motivated by the fact that studies of electron scattering off exotic nuclei are intended in future facilities in the commissioned GSI and RIKEN upgrades, we survey the theoretical predictions from neutron-deficient to neutron-rich isotopes in the tin and calcium isotopic chains. The charge densities of a covariant interaction that describes the low-energy electromagnetic structure of the nucleon within the Lagrangian of the theory are used to this end. The study is restricted to medium and heavy mass nuclei because the charge densities are computed in mean field approach. Since the experimental analysis of scattering data commonly involves parameterized charge densities, as a surrogate exercise for the yet unexplored exotic nuclei, we fit our calculated mean field densities with Helm model distributions. This procedure turns out to be helpful to study the neutron-number variation of the scattering observables and allows us to identify correlations of potential interest among some of these observables within the isotopic chains.Comment: 18 pages, 14 figures, revtex4; modifications in text and figure

    Scaling Calculation of Isoscalar Giant Resonances in Relativistic Thomas-Fermi Theory

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    We derive analytical expressions for the excitation energy of the isoscalar giant monopole and quadrupole resonances in finite nuclei, by using the scaling method and the extended Thomas-Fermi approach to relativistic mean field theory. We study the ability of several non-linear sigma-omega parameter sets of common use in reproducing the experimental data. For monopole oscillations the calculations agree better with experiment when the nuclear matter incompressibility of the relativistic interaction lies in the range 220-260 MeV. The breathing-mode energies of the scaling method compare satisfactorily with those obtained in relativistic RPA and time-dependent mean field calculations. For quadrupole oscillations all the analyzed non-linear parameter sets reproduce the empirical trends reasonably well.Comment: 41 pages, LaTeX, 4 eps figure

    Influence of the single-particle structure on the nuclear surface and the neutron skin

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    We analyze the influence of the single-particle structure on the neutron density distribution and the neutron skin in Ca, Ni, Zr, Sn, and Pb isotopes. The nucleon density distributions are calculated in the Hartree-Fock+BCS approach with the SLy4 Skyrme force. A close correlation is found between the quantum numbers of the valence neutrons and the changes in the position and the diffuseness of the nuclear surface, which in turn affect the neutron skin thickness. Neutrons in the valence orbitals with low principal quantum number and high angular momentum mainly displace the position of the neutron surface outwards, while neutrons with high principal quantum number and low angular momentum basically increase the diffuseness of the neutron surface. The impact of the valence shell neutrons on the tail of the neutron density distribution is discussed.Comment: 17 pages, 14 figure

    MANUFACTURING FLU VACCINE IN MEXICO: A MAJOR PUBLIC HEALTH AND TECHNOLOGY TRANSFER CHALLENGE

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    As Health partner of Mexican Public authorities initiative, Sanofi Pasteur is committed to build a Flu Bulk Vaccine Site, on Mexican soil, in order, for this country, to be self-sufficient for supplying seasonal vaccine and, especially,in case of a Flu Pandemic event. This presentation will give highlights on key drivers to consider while transferring this kind of Technology from Europe to Mexico: - Technology Transfer guidelines: stepwise process - Getting Permits/Authorizations - Looking for partners/Contractors: Engineering and Construction phases - Staffing ramp-up for Manufacturing (Production and Quality Control) start-u
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