84 research outputs found
Relativistic Hartree-Bogoliubov description of ground-state properties of Ni and Sn isotopes
The Relativistic Hartree Bogoliubov (RHB) theory is applied in the
description of ground-state properties of Ni and Sn isotopes. The NL3 parameter
set is used for the effective mean-field Lagrangian, and pairing correlations
are described by the pairing part of the finite range Gogny interaction D1S.
Fully self-consistent RHB solutions are calculated for the Ni () and Sn () isotopes. Binding energies, neutron separation
energies, and proton and neutron radii are compared with experimental
data. The model predicts a reduction of the spin-orbit potential with the
increase of the number of neutrons. The resulting energy splittings between
spin-orbit partners are discussed, as well as pairing properties calculated
with the finite range effective interaction in the channel.Comment: 11 pages, RevTex, 12 p.s figures, submitted to Phys. Rev.
Proton drip-line nuclei in Relativistic Hartree-Bogoliubov theory
Ground-state properties of spherical even-even nuclei and
are described in the framework of Relativistic Hartree Bogoliubov
(RHB) theory. The model uses the NL3 effective interaction in the mean-field
Lagrangian, and describes pairing correlations by the pairing part of the
finite range Gogny interaction D1S. Binding energies, two-proton separation
energies, and proton radii that result from fully self-consistent RHB
solutions are compared with experimental data. The model predicts the location
of the proton drip-line. The isospin dependence of the effective spin-orbit
potential is discussed, as well as pairing properties that result from the
finite range interaction in the channel.Comment: 12 pages, RevTex, 10 p.s figures, submitted to Phys. Rev.
Shell Effects in Nuclei with Vector Self-Coupling of Omega Meson in Relativistic Hartree-Bogoliubov Theory
Shell effects in nuclei about the stability line are investigated within the
framework of the Relativistic Hartree-Bogoliubov (RHB) theory with
self-consistent finite-range pairing. Using 2-neutron separation energies of Ni
and Sn isotopes, the role of - and -meson couplings on the
shell effects in nuclei is examined. It is observed that the existing
successful nuclear forces (Lagrangian parameter sets) based upon the nonlinear
scalar coupling of -meson exhibit shell effects which are stronger than
suggested by the experimental data. We have introduced nonlinear vector
self-coupling of -meson in the RHB theory. It is shown that the
inclusion of the vector self-coupling of -meson in addition to the
nonlinear scalar coupling of -meson provides a good agreement with the
experimental data on shell effects in nuclei about the stability line. A
comparison of the shell effects in the RHB theory is made with the Hartree-Fock
Bogoliubov approach using the Skyrme force SkP. It is shown that the
oft-discussed shell quenching with SkP is not consistent with the available
experimental data.Comment: 34 pages latex, 18 ps figures, replaced with minor corrections in
some figures, accepted for publication in Phys. Rev.
A Dirac-Hartree-Bogoliubov approximation for finite nuclei
We develop a complete Dirac-Hartree-Fock-Bogoliubov approximation to the
ground state wave function and energy of finite nuclei. We apply it to
spin-zero proton-proton and neutron-neutron pairing within the
Dirac-Hartree-Bogoliubov approximation (we neglect the Fock term), using a
zero-range approximation to the relativistic pairing tensor. We study the
effects of the pairing on the properties of the even-even nuclei of the
isotopic chains of Ca, Ni and Sn (spherical) and Kr and Sr (deformed), as well
as the =28 isotonic chain, and compare our results with experimental data
and with other recent calculations.Comment: 43 pages, RevTex, 13 figure
Pairing Properties In Relativistic Mean Field Models Obtained From Effective Field Theory
We apply recently developed effective field theory nuclear models in mean
field approximation (parameter sets G1 and G2) to describe ground-state
properties of nuclei from the valley of -stability up to the drip lines.
For faster calculations of open-shell nuclei we employ a modified BCS approach
which takes into account quasi-bound levels owing to their centrifugal barrier,
with a constant pairing strength. We test this simple prescription by comparing
with available Hartree-plus-Bogoliubov results. Using the new effective
parameter sets we then compute separation energies, density distributions and
spin--orbit potentials in isotopic (isotonic) chains of nuclei with magic
neutron (proton) numbers. The new forces describe the experimental systematics
similarly to conventional non-linear relativistic force
parameters like NL3.Comment: 29 pages, 17 figures, accepted for publication in PR
Continuum effects for the mean-field and pairing properties of weakly bound nuclei
Continuum effects in the weakly bound nuclei close to the drip-line are
investigated using the analytically soluble Poschl-Teller-Ginocchio potential.
Pairing correlations are studied within the Hartree-Fock-Bogoliubov method. We
show that both resonant and non-resonant continuum phase space is active in
creating the pairing field. The influence of positive-energy phase space is
quantified in terms of localizations of states within the nuclear volume.Comment: 27 RevTeX pages, 12 EPS figures included, submitted to Physical
Review
Making sense of local knowledge and indigenous practices on health and biosecurity risk management
The potential for zoonotic emerging infectious diseases (EIDs) to spread worldwide is immense. Geographical boundaries can be uncertain and management of disease crises, biosecurity and health risks is a huge task that requires cooperation and understanding from many parts of the public and private sectors. A glimpse of this has been seen over the years during epidemics, including the bovine spongiform encephalopathy or mad cow disease outbreak in the United Kingdom, Hendra virus outbreaks among horses in Australia, Nipah virus spread in Malaysia and Singapore, and the severe acute respiratory syndrome (SARS) outbreaks in Asia. In the last decade, highly pathogenic avian influenza H5N1 (HPAI H5N1), or ‘bird flu’, outbreaks have also been a focus of global attention.
These zoonotic EIDs have predominantly affected countries in South-East Asia. Why is this so? One obvious factor is the way animals are raised, slaugh¬tered and prepared for food consumption. There are certain animal-rearing practices and human health beliefs in countries in the region that need to be recognised before control programs can be designed. Governance and institutional systems also function differently in countries in the region, affecting the enactment of policies to support biosecurity risk management and preparedness.
International non-government organisations, donor agencies and other humanitarian organisations have supported countries in the region to help eradicate HPAI H5N1. Assistance is given through technical and funding support necessary to build local capacity for disease control, as well as to institute prepared¬ness plans and manage health and biosecurity risks. Resources are poured into the establishment of emergency plans and protocols to prepare for a possible influenza pandemic to minimise global catastrophe
Assessment of a Sampling Plan Based on Visual Inspection for the Detection of Anisakid Larvae in Fresh Anchovies (Engraulis encrasicolus). A First Step Towards Official Validation?
Monomorphic genotypes within a generalist lineage of Campylobacter jejuni show signs of global dispersion
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