RESUMEN
We report here the first observation of the 0_{2}^{+} state of ^{8}He, which has been predicted to feature the condensatelike α+^{2}n+^{2}n cluster structure. We show that this state is characterized by a spin parity of 0^{+}, a large isoscalar monopole transition strength, and the emission of a strongly correlated neutron pair, in line with theoretical predictions. Our finding is further supported by the state-of-the-art microscopic α+4n model calculations. The present results may lead to new insights into clustering in neutron-rich nuclear systems and the pair correlation and condensation in quantum many-body systems under strong interactions.
RESUMEN
The ^{12}C(α,γ)^{16}O reaction is one of the most crucial reactions in nuclear astrophysics. The E2 external capture to the ^{16}O ground state (GS) has not been emphasized in previous analyses but may make a significant contribution to the ^{12}C(α,γ)^{16}O cross section depending on the value of the GS asymptotic normalization coefficient (ANC). In the present work, we determine this ANC to be 337±45 fm^{-1/2} through the ^{12}C(^{11}B,^{7}Li)^{16}O reaction using a high-precision magnetic spectrograph. This sheds light on the existing large discrepancy of more than 2 orders of magnitude between the previously reported ANC values. Based on the new ANC, we experimentally constrain the GS external capture and show that through interference with the high energy tail of the 2^{+} subthreshold state, a substantial enhancement in the GS S_{E2}(300) factor can be obtained (70±7 keV b) compared to that of a recent review (45 keV b), resulting in an increase of the total S factor from 140 to 162 keV b, which is now in good agreement with the value obtained by reproducing supernova nucleosynthesis calculations with the solar-system abundances. This work emphasizes that the external capture contribution for the ground state transition cannot be neglected in future analyses of the ^{12}C(α,γ)^{16}O reaction.
RESUMEN
Twenty patients (18 males, 2 females) with type II (non-insulin-dependent) diabetes mellitus were enrolled in the study. They were aged 49-72 years (mean age 65 years). Radionuclide-labelled water was used to measure oesophageal motility, expressed as the oesophageal mean transit time (MTT). A radionuclide-labelled solid meal was used to measure gastric motility, expressed as the half-time of gastric emptying (T1/2GET). A baseline study was performed before oral erythromycin therapy. After a 2-week course of treatment, the subjects underwent a second study. Fasting blood sugar (FBS) was also monitored in each study. In the baseline study, MTT was 8.88 +/- 2.00 s and T1/2GET was 198.0 +/- 58.9 min. After treatment with erythromycin, MTT decreased to 7.48 +/- 2.24 s (P < 0.01) and T1/2GET decreased to 137.1 +/- 71.2 min (P < 0.01). In addition, the FBS decreased from 159.0 +/- 40.2 mg dl-1 at baseline to 139.2 +/- 39.8 mg dl-1 after 2 weeks of erythromycin treatment (P < 0.05). We conclude that erythromycin is an effective prokinetic agent for diabetic gastroparesis, and that improved oesophageal transit and gastric emptying may improve glycaemic control.
