175 research outputs found

    Astrophysical S_{17}(0) factor from a measurement of d(7Be,8B)n reaction at E_{c.m.} = 4.5 MeV

    Full text link
    Angular distribution measurements of 2^2H(7^7Be,7^7Be)2^2H and 2^2H(7^7Be,8^8B)nn reactions at Ec.m.∼E_{c.m.}\sim~4.5 MeV were performed to extract the astrophysical S17(0)S_{17}(0) factor using the asymptotic normalization coefficient (ANC) method. For this purpose a pure, low emittance 7^7Be beam was separated from the primary 7^7Li beam by a recoil mass spectrometer operated in a novel mode. A beam stopper at 0∘^{\circ} allowed the use of a higher 7^7Be beam intensity. Measurement of the elastic scattering in the entrance channel using kinematic coincidence, facilitated the determination of the optical model parameters needed for the analysis of the transfer data. The present measurement significantly reduces errors in the extracted 7^7Be(p,γ\gamma) cross section using the ANC method. We get S17S_{17}~(0)~=~20.7~±\pm~2.4 eV~b.Comment: 15 pages including 3 eps figures, one figure removed and discussions updated. Version to appear in Physical Review

    Creating a knowledge sharing portal to support the teaching of Malaysian indigenous language

    Get PDF
    Bahasa Semai is one of the indigenous languages that exist in Malaysia and is taught in selected Malaysian primary schools.In sustaining the existence of the biggest indigenous ethnics in Malaysia, it is significant to preserve the existence of their language and best supported with the existing computing technology.The purpose of this paper is to report the process of developing a portal for the usage of Bahasa Semai educators that teach the language to the school children.The portal allows educators to upload their teaching materials, access Bahasa Semai dictionary, share teaching experience with other teachers and communicate with the indigenous language coordinator.Interviews and literature reviews were conducted for the preliminary studies in identifying the functionalities of the portal. The portal was developed by following agile methodology and six educators from two primary schools that offer Bahasa Semai in class were interviewed in the user testing phase.As a result, the educators have positive interests in using the portal and believe that the portal will be able to assist them in teaching the language, especially to educators that Bahasa Semai is not their first language. Moreover, the portal will allow knowledge sharing of Bahasa Semai teachings between educators and coordinators, which will assist in sustaining an indigenous language in Malaysia

    Electromagnetic transition from the 4+^+ to 2+^+ resonance in 8^8Be measured via the radiative capture in 4^4He+4^4He

    Get PDF
    An earlier measurement on the 4+^+ to 2+^+ radiative transition in 8^8Be provided the first electromagnetic signature of its dumbbell-like shape. However, the large uncertainty in the measured cross section does not allow a stringent test of nuclear structure models. The present paper reports a more elaborate and precise measurement for this transition, via the radiative capture in the 4^4He+4^4He reaction, improving the accuracy by about a factor of three. The {\it ab initio} calculations of the radiative transition strength with improved three-nucleon forces are also presented. The experimental results are compared with the predictions of the alpha cluster model and {\it ab initio} calculations.Comment: 5 pages and 7 figures, Submitted to Physical Review Letter

    Large-scale associations between the leukocyte transcriptome and BOLD responses to speech differ in autism early language outcome subtypes.

    Get PDF
    Heterogeneity in early language development in autism spectrum disorder (ASD) is clinically important and may reflect neurobiologically distinct subtypes. Here, we identified a large-scale association between multiple coordinated blood leukocyte gene coexpression modules and the multivariate functional neuroimaging (fMRI) response to speech. Gene coexpression modules associated with the multivariate fMRI response to speech were different for all pairwise comparisons between typically developing toddlers and toddlers with ASD and poor versus good early language outcome. Associated coexpression modules were enriched in genes that are broadly expressed in the brain and many other tissues. These coexpression modules were also enriched in ASD-associated, prenatal, human-specific, and language-relevant genes. This work highlights distinctive neurobiology in ASD subtypes with different early language outcomes that is present well before such outcomes are known. Associations between neuroimaging measures and gene expression levels in blood leukocytes may offer a unique in vivo window into identifying brain-relevant molecular mechanisms in ASD
    • …
    corecore