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The ß-delayed one- and two-neutron emission probabilities (P_{1n} and P_{2n}) of 20 neutron-rich nuclei with N≥82 have been measured at the RIBF facility of the RIKEN Nishina Center. P_{1n} of ^{130,131}Ag, ^{133,134}Cd, ^{135,136}In, and ^{138,139}Sn were determined for the first time, and stringent upper limits were placed on P_{2n} for nearly all cases. ß-delayed two-neutron emission (ß2n) was unambiguously identified in ^{133}Cd and ^{135,136}In, and their P_{2n} were measured. Weak ß2n was also detected from ^{137,138}Sn. Our results highlight the effect of the N=82 and Z=50 shell closures on ß-delayed neutron emission probability and provide stringent benchmarks for newly developed macroscopic-microscopic and self-consistent global models with the inclusion of a statistical treatment of neutron and γ emission. The impact of our measurements on r-process nucleosynthesis was studied in a neutron star merger scenario. Our P_{1n} and P_{2n} have a direct impact on the odd-even staggering of the final abundance, improving the agreement between calculated and observed Solar System abundances. The odd isotope fraction of Ba in r-process-enhanced (r-II) stars is also better reproduced using our new data.
RESUMO
INTRODUCTION: Perinatal mortality rate is a sensitive indicator of quality of care provided to women in pregnancy, at and after child birth and to the newborns in the first week of life. Regular perinatal audit would help in identifying all the factors that play a role in causing perinatal deaths and thus help in appropriate interventions to reduce avoidable perinatal deaths. AIMS AND OBJECTIVES: This study was carried out to determine perinatal mortality rate (PMR) and the factors responsible for perinatal deaths at KMCTH in the two year period from November 2003 to October 2005 (Kartik 2060 B.S. to Ashoj 2062). METHODOLOGY: This is a prospective study of all the still births and early neonatal deaths in KMCTH during the two year period from November 2003 to October 2005. Details of each perinatal death were filled in the standard perinatal death audit forms of the Department of Pediatrics, KMCTH. Perinatal deaths were analyzed according to maternal characteristics like maternal age, parity, type of delivery and fetal characteristics like sex, birth weight and gestational age and classify neonatal deaths according to Wigglesworth's classification and comparison made with earlier similar study. RESULTS: Out of the 1517 total births in the two year period, 22 were still births (SB) and 10 were early neonatal deaths (ENND). Out of the 22 SB, two were of < 1 kg in weight and out of 10 ENND, one was of <1 kg. Thus, perinatal mortality rate during the study period was 19.1 and extended perinatal mortality rate was 21.1 per 1000 births. The important causes of perinatal deaths were extreme prematurity, birth asphyxia, congenital anomalies and associated maternal factors like antepartum hemorrhage and most babies were of very low birth weight. According to Wigglesworth's classification, 43.8% of perinatal deaths were in Group I, 12.5% in Group II, 28.1% in Group III, 12.5% in Group IV and 12.5% in Group V. DISCUSSION: The perinatal death audit done in KMCTH for 1 year period from September 2002 to August 2003 showed perinatal mortality rate of 30.7 and extended perinatal mortality rate of 47.9 per 1000 births. There has been a significant reduction in the perinatal mortality rate in the last 2 years at KMCTH. Main reasons for improvement in perinatal mortality rate were improvement in care of both the mothers and the newborns and the number of births have also increased significantly in the last 2 years without appropriate increase in perinatal deaths. CONCLUSION: Good and regular antenatal care, good care at the time of birth including appropriate and timely intervention and proper care of the sick neonates are important in reducing perinatal deaths. Prevention of preterm births, better care and monitoring during the intranatal period and intensive care of low birth weight babies would help in further reducing perinatal deaths. Key words: Perinatal mortality rate (PMR), still births, early neonatal death (ENND), Total perinatal death (PND).
