3,051 research outputs found
Playing With Fire: The Proposed Flag Burning Amendment and the Perennial Attack on Freedom of Speech
Lattice effective field theory calculations for A = 3,4,6,12 nuclei
We present lattice results for the ground state energies of tritium,
helium-3, helium-4, lithium-6, and carbon-12 nuclei. Our analysis includes
isospin-breaking, Coulomb effects, and interactions up to
next-to-next-to-leading order in chiral effective field theory.Comment: 4 pages, 4 figures, published version to appear in Phys. Rev. Lett
Solar Protons and Magnetic Storms in July 1961
Injun i satellite observations of solar protons and magnetic storm
The equation of state of neutron star matter and the symmetry energy
We present an overview of microscopical calculations of the Equation of State
(EOS) of neutron matter performed using Quantum Monte Carlo techniques. We
focus to the role of the model of the three-neutron force in the high-density
part of the EOS up to a few times the saturation density. We also discuss the
interplay between the symmetry energy and the neutron star mass-radius
relation.
The combination of theoretical models of the EOS with recent neutron stars
observations permits us to constrain the value of the symmetry energy and its
slope. We show that astrophysical observations are starting to provide
important insights into the properties of neutron star matter.Comment: 7 pages, 3 figure, talk given at the 11th International Conference on
Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1,
2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference
Series (JPCS
Quantum Monte Carlo calculations of neutron-alpha scattering
We describe a new method to treat low-energy scattering problems in
few-nucleon systems, and we apply it to the five-body case of neutron-alpha
scattering. The method allows precise calculations of low-lying resonances and
their widths. We find that a good three-nucleon interaction is crucial to
obtain an accurate description of neutron-alpha scattering.Comment: 4 pages, 2 figures, submitted to Physical Review Letter
Pregnancy in women with congenital heart disease
Congenital heart defects are the most common birth defects. Major advances in open-heart surgery have led to rapidly evolving cohorts of adult survivors and the majority of affected women now survive to childbearing age. The risk of cardiovascular complications during pregnancy and peripartum depends on the type of the underlying defect, the extent and severity of residual haemodynamic lesions and comorbidities. Careful individualized, multi-disciplinary pre-pregnancy risk assessment and counselling, including assessment of risks in the offspring and estimation on long-term outcomes of the underlying heart defect, will enable informed decision making. Depending on the estimated risks, a careful follow-up plan during pregnancy as well as a detailed plan for delivery and postpartum care can reduce the risks and should be made by the multi-disciplinary tea
Ab initio calculation of the Hoyle state
The Hoyle state plays a crucial role in the hydrogen burning of stars heavier
than our sun and in the production of carbon and other elements necessary for
life. This excited state of the carbon-12 nucleus was postulated by Hoyle [1]
as a necessary ingredient for the fusion of three alpha particles to produce
carbon at stellar temperatures. Although the Hoyle state was seen
experimentally more than a half century ago [2,3], nuclear theorists have not
yet uncovered the nature of this state from first principles. In this letter we
report the first ab initio calculation of the low-lying states of carbon-12
using supercomputer lattice simulations and a theoretical framework known as
effective field theory. In addition to the ground state and excited spin-2
state, we find a resonance at -85(3) MeV with all of the properties of the
Hoyle state and in agreement with the experimentally observed energy. These
lattice simulations provide insight into the structure of this unique state and
new clues as to the amount of fine-tuning needed in nature for the production
of carbon in stars.Comment: 4 pp, 3 eps figs, version accepted for publication in Physical Review
Letter
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