The rate region of Gaussian multiple description coding with individual and central distortion constraints is completely characterized. Specifically, a lower bound and an upper bound are derived for each supporting hyperplane of the rate region, where the lower bound is associated with a max-min game while the upper bound is associated with a min-max game; furthermore, it is shown that these two bounds coincide due to the existence of a saddle point.
Excited states in 192 Pt and 194 Pt have been studied with high-energy resolution, in the (p, t) reaction, by using the Q3D magnetic spectrograph at the Munich MP tandem accelerator. Outgoing tritons were recorded at laboratory angles sensitive to the unique shape of the L = 0 angular distribution. Sets of previously unknown 0 + states were identified up to an energy of ∼3 MeV. The 0 + states in 192,194 Pt are discussed in the context of the evolution of intruder states and shape coexistence in the light Pt isotopes.
During the slow neutron capture process in massive stars, reactions on light elements can both produce and absorb neutrons thereby influencing the final heavy element abundances. At low metallicities, the high neutron capture rate of 16 O can inhibit s-process nucleosynthesis unless the neutrons are recycled via the 17 O(α,n) 20 Ne reaction. The efficiency of this neutron recycling is determined by competition between the 17 O(α,n) 20 Ne and 17 O(α, γ) 21 Ne reactions. While some experimental data are available on the former reaction, no data exist for the radiative capture channel at the relevant astrophysical energies.The 17 O(α, γ) 21 Ne reaction has been studied directly using the DRAGON recoil separator at the TRIUMF Laboratory. The reaction cross section has been determined at energies between 0.6 and 1.6 MeV E cm , reaching into the Gamow window for core helium burning for the first time. Resonance strengths for resonances at 0.63, 0.721, 0.81 and 1.122 MeV E cm have been extracted. The experimentally based reaction rate calculated represents a lower limit, but suggests that significant s-process nucleosynthesis occurs in low metallicity massive stars.PACS numbers 26.20. Kn, 25.40.Lw
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