5,805 research outputs found

    Ion-beam mixing induced by atomic and cluster bombardment in the electronic stopping-power regime

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    Single crystals of magnesium oxide containing nanoprecipitates of sodium were bombarded with swift ions (∌GeV-Pb, U) or cluster beams (∌20 MeV-C60) to study the phase change induced by electronic processes at high stopping power (≳10 keV/nm). The sodium precipitates and the defect creation were characterized by optical absorption and transmission electron microscopy. The ion or cluster bombardment leads to an evolution of the Na precipitate concentration but the size distribution remains unchanged. The decrease in Na metallic concentration is attributed to mixing effects at the interfaces between Na clusters and MgO. In addition, optical-absorption measurements show a broadening of the absorption band associated with electron plasma oscillations in Na clusters. This effect is due to a decrease of the electron mean free path, which could be induced by defect creation in the metal. All these results show an influence of high electronic stopping power in materials known to be very resistant to irradiation with weak ionizing projectiles. The dependence of these effects on electronic stopping power and on various solid-state parameters is discussed

    Mesure de l'énergie des ions lourds par la méthode des protons projetés

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    Un dispositif destinĂ© Ă  la mesure de l'Ă©nergie des faisceaux d'ions lourds de 3 Ă  6 MeV/ uma a Ă©tĂ© construit. Le principe de la mĂ©thode est de mesurer l'Ă©nergie des protons projetĂ©s Ă  zĂ©ro degrĂ© par collision Ă©lastique des ions incidents avec les noyaux d'hydrogĂšne d'une cible de formvar. L'incertitude calculĂ©e sur l'Ă©nergie ainsi mesurĂ©e pour les ions lourds est de + 0,45 %. Des mesures faites sur des faisceaux de 19F et 40Ca d'Ă©nergie bien connue, accĂ©lĂ©rĂ©s par un Tandem MP, ont montrĂ© un Ă©cart maximum de 0,3 % entre les Ă©nergies rĂ©elles et mesurĂ©es. Le dispositif permet de contrĂŽler ou calibrer des mĂ©thodes plus lourdes de dĂ©termination de l'Ă©nergie des ions lourds : dĂ©viation magnĂ©tique, temps de vol. Il se prĂȘte particuliĂšrement bien Ă  la mesure des pertes d'Ă©nergie d'ions lourds dans des ralentisseurs solides

    The effect of concurrent resistance training on upper body strength, sprint swimming performance and kinematics in competitive adolescent swimmers: a randomized controlled trial

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    This study aimed to examine the effect of 9 weeks of concurrent resistance training (CRT) between resistance on dry land (bench press (BP) and medicine ball throw) and resistance in water (water parachute and hand paddles) on muscle strength, sprint swimming performance and kinematic variables compared by the usual training (standard in-water training). Twenty-two male competitive swimmers participated in this study and were randomly allocated to two groups. The CRT group (CRTG, age = 16.5 ± 0.30 years) performed a CRT program, and the control group (CG, age = 16.1 ± 0.32 years) completed their usual training. The independent variables were measured pre-and post-intervention. The findings showed that the one-repetition maximum bench press (1RM BP) was improved only after a CRT program (d = 2.18; +12.11 ± 1.79%). Moreover, all sprint swimming performances were optimized in the CRT group (d = 1.3 to 2.61; −4.22 ± 0.18% to −7.13 ± 0.23%). In addition, the findings revealed an increase in velocity and stroke rate (d = 1.67, d = 2.24; 9.36 ± 2.55%, 13.51 ± 4.22%, respectively) after the CRT program. The CRT program improved the muscle strength, which, in turn, improved the stroke rate, with no change in the stroke length. Then, the improved stroke rate increased the swimming velocity. Ultimately, a faster velocity leads to better swim performancesinfo:eu-repo/semantics/publishedVersio

    HEAVY ION SECONDARY BEAMS

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    The possibility of producing secondary beams of radioactive nuclei is an interesting application of medium and high energy heavy ion beams. After a first attempt at CERN (1) , two experiments have been performed at GANIL, using 44 MeV/u 40Ar (2) and 65 MeV/u 180 projectiles. This paper recalls the results of the Ar experiment, and presents new data obtained with the 180 beam

    A fast ILP-based Heuristic for the robust design of Body Wireless Sensor Networks

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    We consider the problem of optimally designing a body wireless sensor network, while taking into account the uncertainty of data generation of biosensors. Since the related min-max robustness Integer Linear Programming (ILP) problem can be difficult to solve even for state-of-the-art commercial optimization solvers, we propose an original heuristic for its solution. The heuristic combines deterministic and probabilistic variable fixing strategies, guided by the information coming from strengthened linear relaxations of the ILP robust model, and includes a very large neighborhood search for reparation and improvement of generated solutions, formulated as an ILP problem solved exactly. Computational tests on realistic instances show that our heuristic finds solutions of much higher quality than a state-of-the-art solver and than an effective benchmark heuristic.Comment: This is the authors' final version of the paper published in G. Squillero and K. Sim (Eds.): EvoApplications 2017, Part I, LNCS 10199, pp. 1-17, 2017. DOI: 10.1007/978-3-319-55849-3\_16. The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-55849-3_1

    The Production of Zâ€ČZ' Associated With Photons or Jets as a Probe of New Gauge Boson Couplings

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    We examine the production of a new Zâ€ČZ' gauge boson in association with photons or jets at future hadron supercolliders as a probe of its couplings to fermions. Associated jet production is found to be rather insensitive to these couplings and suffers from large uncertainties as well as substantial backgrounds. On the other hand, the ratio of rates for associated photon Zâ€ČZ' production to that of conventional Zâ€ČZ' production has a rather clean signature (once appropriate cuts are made), and is found to be quite sensitive to the choice of extended electroweak model, while being simultaneously insensitive to structure function uncertainties and QCD corrections. Rates at both the SSC and LHC are significant for Zâ€ČZ' masses in the 1 TeV range.Comment: 14pp, 6 figs(not included), LaTex, ANL-HEP-PR-92-5

    INVESTIGATION OF THE TRANSMISSION AND STOPPING OF LIGHT IONS PASSING THROUGH A PLASMA TARGET

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    Transmission and energy losses of 2 MeV/u Carbon and Sulphur beams passing through a plasma target, have been extensively investigated. A hydrogen plasma ignited by an electrical discharge was coupled to the Orsay Tandem beam accelerator. Fluctuations in beam transmission have been observed and attributed to a magnetic focusing effect generated during the plasma evolution. Energy loss measurements were performed on the basis of time of flight techniques and indicate an enhanced stopping power of the plasma relative to its cold matter equivalent

    Evolution of the One CGIAR’s research and innovation portfolio to 2030 : approaches, tools, and insights after the reform

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    In this perspective, we offer insights into the evolution of CGIAR’s research and innovation portfolio from 2019 to 2023, underpinning the transformative journey towards One CGIAR. With this contribution, we aim to strengthen the social and environmental sustainability components of allied, future Research for Development (R4D) portfolios. We explore three interlinked operational frameworks—Quality of Research for Development (QoR4D), Comparative Advantage (CA) Analysis, and Inclusive Innovation—and present practical tools and lessons for enhancing the quality and impact of R4D initiatives. This work is based on insights gained by the Independent Science for Development Council (ISDC) during the review of proposals for the current One CGIAR research portfolio. QoR4D’s four dimensions (relevance, scientific credibility, legitimacy, and effectiveness) guide research strategy, portfolio development, evaluation and performance standards, fostering intentional design and transparent assessment. CA Analysis leverages organisational strengths, facilitating purposeful partnerships, and strategic resource allocation. Inclusive Innovation emphasises stakeholder inclusivity, amplifying legitimacy, relevance, and effectiveness. Insights are drawn from the application of these frameworks, highlighting the importance of collaboration, the need for a mindset shift and institutional reform, specialisation, and impact maximisation. By adopting these lessons, CGIAR and allied organisations can collectively address global food system challenges more effectively, driving sustainable agricultural innovation and societal transformation. This article aims to contribute to advancing sustainable agriculture and underscores the significance of systemic collaborations in creating more resilient and equitable food systems.Publisher PDFPeer reviewe
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