988 research outputs found

    Three-centre cluster structure in 11C and 11B

    Full text link
    Studies of the 16O(9Be,alpha 7Be)14C, 7Li(9Be,alpha 7Li)5He and 7Li(9Be,alpha alpha t)5He reactions at E(beam)=70 and 55 MeV have been performed using resonant particle spectroscopy techniques. The 11C excited states decaying into alpha+7Be(gs) are observed between 8.5 and 13.5 MeV. The alpha+7Li(gs), alpha+7Li*(4.652 MeV) and t+8Be(gs) decays of 11B excited states between 9 and 19 MeV are observed. The decay processes are used to indicate the possible three-centre 2alpha+3He (2alpha+3H) cluster structure of observed states. This cluster structure is more prominent in the positive-parity states, where two rotational bands with large deformations are suggested. Excitations of some of the observed T=1/2 resonances coincide with the energies of previously measured T=3/2 isobaric analogs of the 11Be states,indicating that these states may have mixed isospin.Comment: Contribution for the proceedings of the NUSTAR'05: NUclear STructure, Astrophysics and Reactions, University of Surrey, Guildford, UK; accepted for publication in Journal of Physics

    Biological invasions as burdens to primary economic sectors

    Get PDF
    Many human-introduced alien species economically impact industries worldwide. Management prioritisation and coordination efforts towards biological invasions are hampered by a lack of comprehensive quantification of costs to key economic sectors. Here, we quantify and estimate global invasion costs to seven major sectors and unravel the introduction pathways of species causing these costs — focusing mainly on primary economic sectors: agriculture, fisheries and forestry. From 1970 to 2020, costs reported in the InvaCost database as pertaining to Agriculture, Fisheries, and Forestry totaled 509bn,509 bn, 1.3 bn, and 134bn,respectively(in2017UnitedStatesdollars).Pathwaysofcostlyspecieswerediverse,arisingpredominantlyfromculturalandagriculturalactivities,throughunintentionalcontaminantswithtrade,andoftenimpacteddifferentsectorsthanthoseforwhichspecieswereinitiallyintroduced.CoststoAgriculturewerepervasiveandgreatestinatleast37134 bn, respectively (in 2017 United States dollars). Pathways of costly species were diverse, arising predominantly from cultural and agricultural activities, through unintentional contaminants with trade, and often impacted different sectors than those for which species were initially introduced. Costs to Agriculture were pervasive and greatest in at least 37 % (n = 46/123) of the countries assessed, with the United States accumulating the greatest costs for primary sectors (365 bn), followed by China (101bn),andAustralia(101 bn), and Australia (36 bn). We further identified 19 countries highly economically reliant on Agriculture, Fisheries, and Forestry that are experiencing massive economic impacts from biological invasions, especially in the Global South. Based on an extrapolation to fill cost data gaps, we estimated total global costs ranging from at least 5171,400bnforAgriculture,517–1,400 bn for Agriculture, 5.7–6.5 bn for Fisheries, and 142768bnforForestry,evidencingsubstantialunderreportingintheForestrysectorinparticular.Burgeoningglobalinvasioncostschallengesustainabledevelopmentandhighlighttheneedforimprovedmanagementactiontoreducefutureimpactsonindustry.Significance:Withrapidlyrisingbiologicalinvasionrates,efficientmanagementiscriticalforeconomicandenvironmentalimpactmitigation.Specifically,improvedquantificationoftheeconomiccostofbiologicalinvasionstotheworldsprimaryeconomicsectorscouldprovidecrucialinformationforpolicymakerswhomustprioritiseactionstolimitongoingandfutureimpacts.Weshowthatsince1970,over142–768 bn for Forestry, evidencing substantial underreporting in the Forestry sector in particular. Burgeoning global invasion costs challenge sustainable development and highlight the need for improved management action to reduce future impacts on industry. Significance: With rapidly rising biological invasion rates, efficient management is critical for economic and environmental impact mitigation. Specifically, improved quantification of the economic cost of biological invasions to the world's primary economic sectors could provide crucial information for policymakers who must prioritise actions to limit ongoing and future impacts. We show that since 1970, over 600 bn in impacts has been incurred across Agriculture, Fisheries and Forestry, with the largest share reported in Agriculture. We further identify 19 countries, which rely heavily on primary sectors, facing comparatively high impacts from invasions, requiring urgent action. However, gaps in cost reporting across invasive taxa and countries suggest that these impacts are grossly underestimated. Proactive prioritisation by policymakers is needed to mitigate future impacts to primary sectors.</p

    Structure of 12Be: intruder d-wave strength at N=8

    Get PDF
    The breaking of the N=8 shell-model magic number in the 12Be ground state has been determined to include significant occupancy of the intruder d-wave orbital. This is in marked contrast with all other N=8 isotones, both more and less exotic than 12Be. The occupancies of the 0 hbar omega neutron p1/2-orbital and the 1 hbar omega, neutron d5/2 intruder orbital were deduced from a measurement of neutron removal from a high-energy 12Be beam leading to bound and unbound states in 11Be.Comment: 5 pages, 2 figure

    Evaluasi Program Pembelajaran Bahasa Inggris

    Get PDF
    The aims of this research were to evaluate English learning in context, input, process, product. This research was an evaluation research. The sources of the research were students of English for Children class at English Smart Bandar Jaya. The data was collected through observation, test, and documentation which was analyzed descriptive quantitative. The conclusions in this research were : 1) the of context value of sub component at the pre-condition is fair, the input value of component sub component infrastructure,human resources and curriculum is poor, the result of process component sub component of planning and english learning implementation is fair, and the product component value in the learning result of the students is fair, and 2) the recommendation of this research,the general manager needs to observe and change the curriculum for a better future, then provide laboratory room for listening, the teachers should make a lesson plan based on the syllabus for each competency.Penelitian ini bertujuan untuk mengevaluasi pembelajaran Bahasa Inggris pada komponen context, input, process, product. Penelitian ini merupakan penelitian evaluasi. Sumber penelitian adalah pembelajar kelas English for Children di English Smart Bandar Jaya. Data dikumpulkan dengan observasi, tes dan dokumentasi kemudian dianalisis secara deskriptif kuantitatif. Kesimpulan dalam penelitian ini : 1) nilai context sub komponen kondisi awal lembaga cukup, nilai input sub komponen fasilitas sarana prasarana, tenaga pendidik dan kurikulum cukup, nilai process sub komponen perencanaan dan pelaksanaan pembelajaran bahasa Inggris kurang, dan nilai komponen product pada hasil belajar pembelajar cukup, dan 2) rekomendasi penelitian ini, kepala lembaga perlu meninjau atau mengubah kurikulum lembaga untuk pembaruan ke arah yang lebih baik, disediakan ruang laboratorium untuk menunjang pembelajaran listening, tentor harus membuat lesson plan yang disusun berdasarkan silabus unit kompetensi

    Individual differences in second language speech learning in classroom settings: roles of awareness in the longitudinal development of Japanese learners’ English /ɹ/ pronunciation

    Get PDF
    The current study longitudinally examined a crucial individual difference variable—i.e., awareness (operationalized as explicit attention and articulatory knowledge)—in adult second language (L2) speech learning in the context of 40 Japanese learners’ English /ɹ/ pronunciation development in an EFL classroom. The participants’ speech, elicited from word reading, sentence reading and timed picture description tasks at the beginning and end of one academic semester, were analyzed in terms of three acoustic dimensions of English /ɹ/—third formant (F3), second formant (F2) and duration. Whereas the participants showed gains in the relatively easy aspect of the English /ɹ/ acquisition (F2 reduction) as a function of increased L2 input, their explicit awareness of accurate English /ɹ/ pronunciation played a significant role in the acquisition of the relatively difficult dimension (lengthening phonemic duration). The awareness-acquisition link was not found, however, for the most difficult dimension (F3 reduction) at least within the timeframe of the project

    Structure of 13^{13}Be probed via secondary beam reactions

    Full text link
    The low-lying level structure of the unbound neutron-rich nucleus 13^{13}Be has been investigated via breakup on a carbon target of secondary beams of 14,15^{14,15}B at 35 MeV/nucleon. The coincident detection of the beam velocity 12^{12}Be fragments and neutrons permitted the invariant mass of the 12^{12}Be+nn and 12^{12}Be+nn+nn systems to be reconstructed. In the case of the breakup of 15^{15}B, a very narrow structure at threshold was observed in the 12^{12}Be+nn channel. Contrary to earlier stable beam fragmentation studies which identified this as a strongly interacting ss-wave virtual state in 13^{13}Be, analysis here of the 12^{12}Be+nn+nn events demonstrated that this was an artifact resulting from the sequential-decay of the 14^{14}Be(2+^+) state. Single-proton removal from 14^{14}B was found to populate a broad low-lying structure some 0.70 MeV above the neutron-decay threshold in addition to a less prominent feature at around 2.4 MeV. Based on the selectivity of the reaction and a comparison with (0-3)ω\hbar\omega shell-model calculations, the low-lying structure is concluded to most probably arise from closely spaced Jπ^\pi=1/2+^+ and 5/2+^+ resonances (Er_r=0.40±\pm0.03 and 0.850.11+0.15^{+0.15}_{-0.11} MeV), whilst the broad higher-lying feature is a second 5/2+^+ level (Er_r=2.35±\pm0.14 MeV). Taken in conjunction with earlier studies, it would appear that the lowest 1/2+^+ and 1/2^- levels lie relatively close together below 1 MeV.Comment: 14 pages, 13 figures, 2 tables. Accepted for publication in Physical Review

    Native Speaker Perceptions of Accented Speech: The English Pronunciation of Macedonian EFL Learners

    Get PDF
    The paper reports on the results of a study that aimed to describe the vocalic and consonantal features of the English pronunciation of Macedonian EFL learners as perceived by native speakers of English and to find out whether native speakers who speak different standard variants of English perceive the same segments as non-native. A specially designed computer web application was employed to gather two types of data: a) quantitative (frequency of segment variables and global foreign accent ratings on a 5-point scale), and b) qualitative (open-ended questions). The result analysis points out to three most frequent markers of foreign accent in the English speech of Macedonian EFL learners: final obstruent devoicing, vowel shortening and substitution of English dental fricatives with Macedonian dental plosives. It also reflects additional phonetic aspects poorly explained in the available reference literature such as allophonic distributional differences between the two languages and intonational mismatch

    Emergence of the N=16 shell gap in 21O

    Get PDF
    The spectroscopy of O21 has been investigated using a radioactive O20 beam and the (d,p) reaction in inverse kinematics. The ground and first excited states have been determined to be Jπ=5/2+ and 1/2+, respectively. Two neutron unbound states were observed at excitation energies of 4.77(10) and 6.17(11) MeV. The spectroscopic factor deduced for the lower of these, interpreted as a 3/2+ level, reveals a relatively pure (60%) 0d3/2 single-particle configuration, in good agreement with shell-model calculations that predict O26 to be unbound. The large energy difference between the 3/2+ and 1/2+ states is indicative of the emergence of the N=16 shell gap, which is estimated to be 5.1(11) MeV. For the higher-lying resonance, which has a character consistent with a spin-parity assignment of 3/2+ or 7/2-, a 0.71(22) branching ratio to the first 2+ state in O20 has been observed.Unión Europea EURISOL 515768 RIDSNSF PHY-075809

    4He decay of excited states in 14C

    Full text link
    A study of the 7Li(9Be,4He 10Be)2H reaction at E{beam}=70 MeV has been performed using resonant particle spectroscopy techniques and provides the first measurements of alpha-decaying states in 14C. Excited states are observed at 14.7, 15.5, 16.4, 18.5, 19.8, 20.6, 21.4, 22.4 and 24.0 MeV. The experimental technique was able to resolve decays to the various particle bound states in 10Be, and provides evidence for the preferential decay of the high energy excited states into states in 10Be at ~6 MeV. The decay processes are used to indicate the possible cluster structure of the 14C excited states.Comment: accepted for publication in PR
    corecore