350 research outputs found
Microscopic model analyses of proton scattering from 12C, 20Ne, 24Mg, 28Si and 40Ca
Differential cross sections and analyzing powers for elastic scattering from,
and for inelastic proton scattering to a set of states in, C,
Ne, Mg, Si and Ca, and for a set of
energies between 35 to 250 MeV, have been analyzed. A -folding model has
been used to determine optical potentials and a microscopic distorted wave
approximation taken to analyze the inelastic data. The effective
nucleon-nucleon interactions used to specify the optical potentials have also
been used as the transition operators in the inelastic scattering processes.
Shell and large space Hartree-Fock models of structure have been used to
describe the nuclear states.Comment: 27 pages, 18 figure
14Be(p,n)14B reaction at 69 MeV in inverse kinematics
A Gamow-Teller (GT) transition from the drip-line nucleus 14Be to 14B was
studied via the (p,n) reaction in inverse kinematics using a secondary 14Be
beam at 69 MeV/nucleon. The invariant mass method is employed to reconstruct
the energy spectrum. A peak is observed at an excitation energy of 1.27(2) MeV
in 14B, together with bumps at 2.08 and 4.06(5) MeV. The observed forward
peaking of the state at 1.27 MeV and a good description for the differential
cross section, obtained with a DWBA calculation provide support for the 1+
assignment to this state. By extrapolating the cross section to zero momentum
transfer the GT-transition strength is deduced. The value is found to compare
well with that reported in a beta-delayed neutron emission study.Comment: 5 pages, 2 figure
Shell-model calculations of neutrino scattering from 12C
Neutrino reaction cross-sections, , ,
-capture and photoabsorption rates on C are computed within a
large-basis shell-model framework, which included excitations up to
. When ground-state correlations are included with an open
-shell the predictions of the calculations are in reasonable agreement with
most of the experimental results for these reactions. Woods-Saxon radial wave
functions are used, with their asymptotic forms matched to the experimental
separation energies for bound states, and matched to a binding energy of 0.01
MeV for unbound states. For comparison purposes, some results are given for
harmonic oscillator radial functions. Closest agreement between theory and
experiment is achieved with unrestricted shell-model configurations and
Woods-Saxon radial functions. We obtain for the neutrino-absorption inclusive
cross sections: cm for the
decay-in-flight flux in agreement with the LSND datum of
cm; and cm for the decay-at-rest flux, less than the
experimental result of cm.Comment: 19 pages. ReVTeX. No figure
The metabolic, virulence and antimicrobial resistance profiles of colonising Streptococcus pneumoniae shift after PCV13 introduction in urban Malawi
Streptococcus pneumoniae causes substantial mortality among children under 5-years-old worldwide. Polysaccharide conjugate vaccines (PCVs) are highly effective at reducing vaccine serotype disease, but emergence of non-vaccine serotypes and persistent nasopharyngeal carriage threaten this success. We investigated the hypothesis that following vaccine, adapted pneumococcal genotypes emerge with the potential for vaccine escape. We genome sequenced 2804 penumococcal isolates, collected 4-8 years after introduction of PCV13 in Blantyre, Malawi. We developed a pipeline to cluster the pneumococcal population based on metabolic core genes into “Metabolic genotypes” (MTs). We show that S. pneumoniae population genetics are characterised by emergence of MTs with distinct virulence and antimicrobial resistance (AMR) profiles. Preliminary in vitro and murine experiments revealed that representative isolates from emerging MTs differed in growth, haemolytic, epithelial infection, and murine colonisation characteristics. Our results suggest that in the context of PCV13 introduction, pneumococcal population dynamics had shifted, a phenomenon that could further undermine vaccine control and promote spread of AMR
Do Hadronic Charge Exchange Reactions Measure Electroweak L = 1 Strength?
An eikonal model has been used to assess the relationship between calculated
strengths for first forbidden beta decay and calculated cross sections for
(p,n) charge exchange reactions. It is found that these are proportional for
strong transitions, suggesting that hadronic charge exchange reactions may be
useful in determining the spin-dipole matrix elements for astrophysically
interesting leptonic transitions.Comment: 14 pages, 5 figures, Submitted to Physical Review
Cross-sectional health centre and community-based evaluation of the impact of pneumococcal and malaria vaccination on antibiotic prescription and usage, febrile illness and antimicrobial resistance in young children in Malawi: the IVAR study protocol
INTRODUCTION: Vaccination is a potentially critical component of efforts to arrest development and dissemination of antimicrobial resistance (AMR), though little is known about vaccination impact within low-income and middle-income countries. This study will evaluate the impact of vaccination on reducing carriage prevalence of resistant Streptococcus pneumoniae and extended spectrum beta-lactamase-producing Escherichia coli and Klebsiella species. We will leverage two large ongoing cluster-randomised vaccine evaluations in Malawi assessing; first, adding a booster dose to the 13-valent pneumococcal conjugate vaccine (PCV13) schedule, and second, introduction of the RTS,S/AS01 malaria vaccine. METHODS AND ANALYSIS: Six cross-sectional surveys will be implemented within primary healthcare centres (n=3000 users of outpatient facilities per survey) and their local communities (n=700 healthy children per survey): three surveys in Blantyre district (PCV13 component) and three surveys in Mangochi district (RTS,S/AS01 component). We will evaluate antibiotic prescription practices and AMR carriage in children ≤3 years. For the PCV13 component, surveys will be conducted 9, 18 and 33 months following a 3+0 to 2+1 schedule change. For the RTS,S/AS01 component, surveys will be conducted 32, 44 and 56 months post-RTS,S/AS01 introduction. Six health centres in each study component will be randomly selected for study inclusion. Between intervention arms, the primary outcome will be the difference in penicillin non-susceptibility prevalence among S. pneumoniae nasopharyngeal carriage isolates in healthy children. The study is powered to detect an absolute change of 13 percentage points (ie, 35% vs 22% penicillin non-susceptibility). ETHICS AND DISSEMINATION: This study has been approved by the Kamuzu University of Health Sciences (Ref: P01-21-3249), University College London (Ref: 18331/002) and University of Liverpool (Ref: 9908) Research Ethics Committees. Parental/caregiver verbal or written informed consent will be obtained prior to inclusion or recruitment in the health centre-based and community-based activities, respectively. Results will be disseminated via the Malawi Ministry of Health, WHO, peer-reviewed publications and conference presentations
First case report of a successfully managed severe COVID-19 infection in Malawi
The coronavirus disease 2019 (COVID-19) pandemic is now established on the African continent, with cases rapidly increasing in Malawi (1742 confirmed cases and 19 deaths as of 5 July 20201). Clinicians require guidelines, deliverable in the Malawi context, to effectively and safely treat patients for the best possible outcome. In Malawi, key public messages around social distancing, hand washing and shielding for at-risk individuals have been widely distributed by the Ministry of Health. However, it has not been possible to implement strict lockdown measures in Malawi due to the risk of widespread economic disruption, hunger, worsened food insecurity, risk of violence and mass political rallies. Testing rates are low such that the number of confirmed cases in Malawi is likely to significantly under-represent the actual number of cases. As the epidemic unfolds, it is vital that doctors implement standardised case management guidelines to improve survival for patients who require hospital admission. The majority of patients hospitalised with COVID-19 require medical-ward level care, including provision of adequate oxygen3. Increased oxygen provision has been a major focus of COVID-19 preparedness activities in Malawi
Upper-Body Strength Measures and Pop-Up Performance of Stronger and Weaker Surfers
The primary purpose of this study was to investigate the reliability of the isometric push-up (IPU), dynamic push-up (DPU), and force plate pop-up (FP POP) as measures of upper-body isometric and dynamic strength qualities in surfing athletes. Furthermore, the study aimed to compare pop-up performance between stronger and weaker surfers. Eighteen female (n=9) and male (n=9) surfers (age=28.1±6.4 yrs, mass=69.6±10.4 kg, height=172.5±6.7 cm) completed a battery of upper-body strength assessments, of which exhibited high between-day reliability: (IPU, (CV%=4.7, ICC=0.96), DPU (CV%=5.0, ICC=0.90), FP POP (CV%=4.4, ICC=0.90). Participants were subsequently split into stronger (n=9) and weaker (n=9) surfers based on normalized peak force (PF) attained in the IPU. Pop-up performance was measured both in the water and during the FP POP, and was referred to as time to pop (TTP). Significant between group differences were observed for normalized PF during IPU (d=1.59,
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