1,596 research outputs found
Thomas-Fermi approximation to static vortex states in superfluid trapped atomic gases
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
We present a new semi-classical theory for describing pairing in finite Fermi
systems. It is based in taking the , 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?
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
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
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
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
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
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
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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