RESUMO
^{140}Ce(n,γ) is a key reaction for slow neutron-capture (s-process) nucleosynthesis due to being a bottleneck in the reaction flow. For this reason, it was measured with high accuracy (uncertainty ≈5%) at the n_TOF facility, with an unprecedented combination of a high purity sample and low neutron-sensitivity detectors. The measured Maxwellian averaged cross section is up to 40% higher than previously accepted values. Stellar model calculations indicate a reduction around 20% of the s-process contribution to the Galactic cerium abundance and smaller sizeable differences for most of the heavier elements. No variations are found in the nucleosynthesis from massive stars.
RESUMO
The 63Ni(n,γ) cross section has been measured for the first time at the neutron time-of-flight facility n_TOF at CERN from thermal neutron energies up to 200 keV. In total, capture kernels of 12 (new) resonances were determined. Maxwellian averaged cross sections were calculated for thermal energies from kT=5-100 keV with uncertainties around 20%. Stellar model calculations for a 25Mâ star show that the new data have a significant effect on the s-process production of 63Cu, 64Ni, and 64Zn in massive stars, allowing stronger constraints on the Cu yields from explosive nucleosynthesis in the subsequent supernova.
RESUMO
A case of massive epicardial lipoma in an asymptomatic patient is presented. The diagnosis of solid intrapericardial mass was achieved by two-dimensional echocardiography without cardiac catheterization. The complications of postoperative course, which included myocardial infarction, cerebral embolism, and the patient's late sudden death, suggest that the cardiopulmonary bypass should be used in similar circumstances. Lipomas of the heart should be kept in mind in patients with unexplained enlargement of the cardiac silhouette whenever pericardial effusion and heart disease may be excluded.
