97 research outputs found

    First measurement of the helicity asymmetry for γppπ0\gamma p\rightarrow p\pi^0 in the resonance region

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    The first measurement of the helicity dependence of the photoproduction cross section of single neutral pions off protons is reported for photon energies from 600 to 2300\,MeV, covering nearly the full solid angle. The data are compared to predictions from the SAID, MAID, and BnGa partial wave analyses. Strikingly large differences between data and predictions are observed which are traced to differences in the helicity amplitudes of well known and established resonances. Precise values for the helicity amplitudes of several resonances are reported

    Experimental constraints on the ω\omega-nucleus real potential

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    In a search for ω\omega mesic states, the production of ω\omega-mesons in coincidence with forward going protons has been studied in photon induced reactions on 12^{12}C for incident photon energies of 1250 - 3100 MeV. The π0γ\pi^0 \gamma pairs from decays of bound or quasi-free ω\omega-mesons have been measured with the CBELSA/TAPS detector system in coincidence with protons registered in the MiniTAPS forward array. Structures in the total energy distribution of the π0γ\pi^0 \gamma pairs, which would indicate the population and decay of bound ω 11\omega~^{11}B states, are not observed. The π0γ\pi^0 \gamma cross section of 0.3 nb/MeV/sr observed in the bound state energy regime between -100 and 0 MeV may be accounted for by yield leaking into the bound state regime because of the large in-medium width of the ω\omega-meson. A comparison of the measured total energy distribution with calculations suggests the real part V0V_0 of the ω 11\omega~^{11}B potential to be small and only weakly attractive with V0(ρ=ρ0)=15±V_0(\rho=\rho_0) = -15\pm 35(stat) ±\pm20(syst) MeV in contrast to some theoretical predictions of attractive potentials with a depth of 100 - 150 MeV.Comment: 13 pages, 8 figure

    Photoproduction of eta mesons from the neutron: cross sections and double polarization observable E

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    Photoproduction of η\eta mesons from neutrons} \abstract{Results from measurements of the photoproduction of η\eta mesons from quasifree protons and neutrons are summarized. The experiments were performed with the CBELSA/TAPS detector at the electron accelerator ELSA in Bonn using the η3π06γ\eta\to3\pi^{0}\to6\gamma decay. A liquid deuterium target was used for the measurement of total cross sections and angular distributions. The results confirm earlier measurements from Bonn and the MAMI facility in Mainz about the existence of a narrow structure in the excitation function of γnnη\gamma n\rightarrow n\eta. The current angular distributions show a forward-backward asymmetry, which was previously not seen, but was predicted by model calculations including an additional narrow P11P_{11} state. Furthermore, data obtained with a longitudinally polarized, deuterated butanol target and a circularly polarized photon beam were analyzed to determine the double polarization observable EE. Both data sets together were also used to extract the helicity dependent cross sections σ1/2\sigma_{1/2} and σ3/2\sigma_{3/2}. The narrow structure in the excitation function of γnnη\gamma n\rightarrow n\eta appears associated with the helicity-1/2 component of the reaction

    Evaluation and pharmacovigilance of projects promoting cultivation and local use of Artemisia annua for malaria

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    <p>Abstract</p> <p>Background</p> <p>Several non-governmental organisations (NGOs) are promoting the use of <it>Artemisia annua </it>teas as a home-based treatment for malaria in situations where conventional treatments are not available. There has been controversy about the effectiveness and safety of this approach, but no pharmacovigilance studies or evaluations have been published to date.</p> <p>Method</p> <p>A questionnaire about the cultivation of <it>A. annua</it>, treatment of patients, and side-effects observed, was sent to partners of the NGO Anamed in Kenya and Uganda. Some of the respondents were then selected purposively for more in-depth semi-structured interviews.</p> <p>Results</p> <p>Eighteen partners in Kenya and 21 in Uganda responded. 49% reported difficulties in growing the plant, mainly due to drought. Overall about 3,000 cases of presumed malaria had been treated with <it>A. annua </it>teas in the previous year, of which about 250 were in children and 54 were in women in the first trimester of pregnancy. The commonest problem observed in children was poor compliance due to the bitter taste, which was improved by the addition of sugar or honey. Two miscarriages were reported in pregnant patients. Only four respondents reported side-effects in other patients, the commonest of which was vomiting. 51% of respondents had started using <it>A. annua </it>tea to treat illnesses other than malaria.</p> <p>Conclusions</p> <p>Local cultivation and preparation of <it>A. annua </it>are feasible where growing conditions are appropriate. Few adverse events were reported even in children and pregnant women. Where ACT is in short supply, it would make sense to save it for young children, while using <it>A. annua </it>infusions to treat older patients who are at lower risk. An ongoing pharmacovigilance system is needed to facilitate reporting of any adverse events.</p

    Struggles over access to the Muslim public sphere: Multiple publics and discourses on agency, belonging and citizenship (Introduction to the Themed Section)

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    Abstract This introductory essay provides the context for the articles in this Themed Section. Despite the diversity in locations, historical backgrounds and contemporary processes of change, all contributors to this Themed Section focus on the struggle of Muslim groups over access to an emergent Muslim public sphere. They highlight the contestations of and shifts in the notions of agency, belonging, and citizenship in nation-states with Muslim communities within its borders. The introduction consists of two parts. The first part reviews the notion of the public sphere as conceptualized by Habermas and critiqued by scholars of a diversity of backgrounds. In relation to the concept of the Muslim public sphere, three aspects of critique are given closer c

    Comparison of risk-scoring systems in the prediction of outcome after liver resection

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    Background: Risk prediction techniques commonly used in liver surgery include the American Society of Anesthesiologists (ASA) grading, Charlson Comorbidity Index (CCI) and cardiopulmonary exercise tests (CPET). This study compares the utility of these techniques along with the number of segments resected as predictive tools in liver surgery. Methods: A review of a unit database of patients undergoing liver resection between February 2008 and January 2015 was undertaken. Patient demographics, ASA, CCI and CPET variables were recorded along with resection size. Clavien-Dindo grade III–V complications were used as a composite outcome in analyses. Association between predictive variables and outcome was assessed by univariate and multivariate techniques. Results: One hundred and seventy-two resections in 168 patients were identified. Grade III–V complications occurred after 42 (24.4%) liver resections. In univariate analysis of CPET variables, ventilatory equivalents for CO2 (VEqCO2) was associated with outcome. CCI score, but not ASA grade, was also associated with outcome. In multivariate analysis, the odds ratio of developing grade III–V complications for incremental increases in VEqCO2, CCI and number of liver segments resected were 1.09, 1.49 and 2.94, respectively. Conclusions: Of the techniques evaluated, resection size provides the simplest and most discriminating predictor of significant complications following liver surgery

    New data on γpηp\vec{\gamma} \vec{p}\rightarrow \eta p with polarized photons and protons and their implications for NNηN^* \to N\eta decays

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    The polarization observables T,E,P,HT, E, P, H, and GG in photoproduction of η\eta mesons off protons are measured for photon energies from threshold to W=2400W=2400\,MeV (TT), 2280 MeV (EE), 1620 MeV (P,HP, H), or 1820 MeV (GG), covering nearly the full solid angle. The data are compared to predictions from the SAID, MAID, J\"uBo, and BnGa partial-wave analyses. A refit within the BnGa approach including further data yields precise branching ratios for the NηN\eta decay of nucleon resonances. A NηN\eta-branching ratio of 0.33±0.040.33\pm 0.04 for N(1650)1/2N(1650)1/2^- is found, which reduces the large and controversially discussed NηN\eta-branching ratio difference of the two lowest mass JP=1/2J^P=1/2^--resonances significantly.Comment: 10 pages, 11 figure

    Well-established nucleon resonances revisited by double-polarization measurements

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    The first measurement is reported of the double-polarization observable G in photoproduction of neutral pions off protons, covering the photon energy range from 620 to 1120 MeV and the full solid angle. G describes the correlation between the photon polarization plane and the scattering plane for protons polarized along the direction of the incoming photon. The observable is highly sensitive to contributions from baryon resonances. The new results are compared to the predictions from SAID, MAID, and BnGa partial wave analyses. In spite of the long-lasting efforts to understand {\gamma}p -> p{\pi} 0 as the simplest photoproduction reaction, surprisingly large differences between the new data and the latest predictions are observed which are traced to different contributions of the N (1535) with spin-parity J^P = 1/2^- and N (1520) with J^P = 3/2^- . In the third resonance region, where N (1680) with J^P = 5/2^+ production dominates, the new data are reasonably close to the predictions.Comment: Submitted for publication in PR

    Prevalence of anaemia in older persons: systematic review

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    <p>Abstract</p> <p>Background</p> <p>Ageing populations will impact on healthcare provision, especially since extra years are not necessarily spent in good health. It is important to identify and understand the significance of common medical problems in older people. Anaemia may be one such problem. We report on the prevalence of anaemia in cohorts of elderly people in the general population. The presence of anaemia is associated with a worse prognosis for both morbidity and mortality.</p> <p>Methods</p> <p>Electronic searching and reference lists of published reports were used to identify studies that reported on prevalence of anaemia in cohorts of at least 100 individuals predominantly aged 65 years and over living in developed countries, together with criteria used to define anaemia. Studies of anaemia prevalence in specific disease groups or published before 1980 were excluded. Prevalence data for the entire cohort, for men and women separately and for different age bands were extracted.</p> <p>Results</p> <p>Forty-five studies contributed data. Thirty-four studies (n = 85,409) used WHO criteria to define anaemia. The weighted mean prevalence was 17% (3–50%) overall, and 12% (3–25%) in studies based in the community (27, n = 69,975), 47% (31–50%) in nursing homes (3, n = 1481), and 40% (40–72%) in hospital admissions (4, n = 13,953). Anaemia prevalence increased with age, was slightly higher in men than women, and was higher in black people than white. Most individuals classified as anaemic using WHO criteria were only mildly anaemic.</p> <p>Conclusion</p> <p>Anaemia, as defined by WHO criteria, is common in older people living in the community and particularly common in nursing home residents and hospital admissions. Predicted demographic changes underline the need to understand more about anaemia in older people.</p
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