646 research outputs found

    Disentangling unclear nuclear breakup channels of beryllium-9 using the three-axis Dalitz plot

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    The three-axis Dalitz plot has been applied to the breakup of a nucleus into unequal mass fragments for the first time. The Dalitz plot allows clear identification of the various breakup channels of 9Be → 2α + n process. The method has allowed the branching ratio for the 6.38 MeV level in9Be to be provisionally calculated when examining the 9Be(4He, α)ααn reaction. The effects of non-uniform angular distributions on the Dalitz plot must still be properly investigated along with the effects of contaminant reaction channels. It is proposed that this method could be used to determine the breakup branching ratio of a newly-measured level in this nucleus

    Breakup branches of Borromean beryllium-9

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    The breakup reaction 9Be(4He, 3α)n was measured using an array of four double-sided silicon strip detectors at beam energies of 22 and 26 MeV. Excited states in 9Be up to 12 MeV were populated and reconstructed through the measurement of the charged reaction products. It is proposed that limits on the spins and parities of the states can be derived from the way that they decay. Various breakup paths for excited states in 9Be have been explored including the 8Be(g.s.) + n, 8Be(2+) + n and 5He(g.s.) + 4He channels. By imposing the condition that the breakup proceeded via the 8Be ground state, clean excitation spectra for 9Be were reconstructed. The remaining two breakup channels were found to possess strongly-overlapping kinematic signatures and more sophisticated methods (referenced) are required to completely disentangle these other possibilities. Emphasis is placed on the development of the experimental analysis and the usefulness of Monte-Carlo simulations for this purpose

    Evidence for a 3.8 MeV state in 9Be

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    The breakup reaction 9Be(4He,3a)n was measured using an array of four double-sided silicon strip detectors at beam energies of 22 and 26 MeV. Excited states in 9Be up to 8 MeV were populated and reconstructed through measurements of the charged reaction products. Evidence is given for a state in 9Be at 3.82-0.09+0.08 MeV with width=1240-90+270 keV. This is consistent with two recent measurements of a state with similar properties in the mirror nucleus 9B. An analysis of the reduced widths (Beg.s.8 channel) of this state along with the proposed mirror state has led to a firm limit of J<=7/2 and a tentative assignment of J^pi=1/2- or 3/2-

    Low coverage of intermittent preventive treatment for malaria in pregnancy in Nigeria: demand-side influences

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    BACKGROUND: Nigeria instituted intermittent preventive treatment for malaria (IPTp) using sulphadoxine-pyrimethamine (SP) for pregnant women in 2001, but coverage remains low. This study examined the influence of demand side factors on IPTp coverage. METHODS: Data were collected using a household survey from 1307 women who were delivered of a live baby within the one-year period preceding the study and through an exit poll from 146 women attending antenatal clinics (ANC). Data analysis examined coverage based on the national and WHO guidelines for IPTp delivery which differ with regards to use of IPTp in the last month of pregnancy. Focus group discussions (FGDs) were undertaken to further explain demand side constraints to coverage. RESULTS: From the household survey, 96.1% of respondents attended ANC, with most having five or more visits. Overall IPTp coverage for the first and second doses was 13.7% and 7.3% respectively. The coverage was higher in the urban areas compared to rural areas (p < 0.01). Amongst women who could have received IPTp based on the timing of their attendance, only 14.1% and 14.3% were offered the first dose based on national and WHO guidelines, while 7.7% and 7.5% were offered the second dose respectively giving significant missed opportunities. Amongst ANC attendees offered first and second doses, 98.9% and 96.9% respectively took the medicine. Only 13.6% and 21.5% of these clients reported taking the drug under direct observation. The low level of coverage was confirmed by exit survey data, which found coverage of 11.6% and 3.0% for the first and second doses. The FGDs revealed that women do not have many concerns about side effects, but they take drugs providers give them because they believe such drugs must be safe. CONCLUSION: This study found low coverage of IPTp and high levels of missed opportunities supporting findings that high ANC attendance does not guarantee high IPTp coverage. Demand side factors such as ANC attendance, appropriate timing of attendance, and perceptions about side effects were not constraining factors to increased coverage, raising the need to examine supply side factors

    The sarcoma diagnostic interval: a systematic review on length, contributing factors and patient outcomes

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    Sarcomas are rare and heterogeneous mesenchymal tumours of soft tissue or bone, making them prone to late diagnosis. In other malignancies, early diagnosis has an impact on stage of disease, complexity of therapeutic procedures, survival and health-related quality of life (HRQoL). Little is known about what length of diagnostic interval should be considered as delay in patients with bone (BS) or soft tissue sarcomas (STS). To quantify total interval (defined as time from first symptom to histological diagnosis) and its components, identify contributing factors to its length and determine the impact on patients’ outcome in terms of mortality and HRQoL. A systematic review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Seventy-six articles out of 2310 met the predefined inclusion criteria. Total intervals, varied broadly; 9–120.4 weeks for BS and 4.3–614.9 weeks for STS. Older age and no initial radiological examinations were contributing factors for a long interval in BS, while in STS results were conflicting. The impact of length of total interval on clinical outcomes in terms of survival and morbidity remains ambiguous; no clear relation could be identified for both BS and STS. No study examined the impact on HRQoL. The length of total interval is variable in BS as well as STS. Its effect on outcomes is contradictory. There is no definition of a clinically relevant cut-off point that discriminates between a short or long total interval. Prospero: CRD42017062492

    alpha-decay of excited states in 11C and 11B

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    Studies of the 16O(9Be,alpha7Be)14C and 7Li(9Be,alpha7Li)5He reactions at E{beam}=70 MeV have been performed using resonant particle spectroscopy techniques. The 11C excited states decaying into alpha+7Be(gs) are observed at 8.65, 9.85, 10.7 and 12.1 MeV as well as possible states at 12.6 and 13.4 MeV. This result is the first observation of alpha-decay for excited states above 9 MeV. The alpha+7Li(gs) decay of 11B excited states at 9.2, 10.3, 10.55, 11.2, (11.4), 11.8, 12.5,(13.0), 13.1, (14.0), 14.35, (17.4) and (18.6) MeV is observed. The decay processes are used to indicate the possible three-centre 2alpha+3He(3H) cluster structure of observed states. Two rotational bands corresponding to very deformed structures are suggested for the positive-parity states. Excitations of some observed T=1/2 resonances coincide with the energies of T=3/2 states which are the isobaric analogs of the lowest 11Be states. Some of these states may have mixed isospin.Comment: accepted for publication in Nuclear Physics
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