909 research outputs found

    Comment on "Electromagnetic dissociation of ^8B and the astrophysical S-factor for ^7Be(p,gamma)^8B"

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    Recently, Davids and Typel recommended a "low" value of S_{17}(0) based on fits to published direct and Coulomb dissociation data, in which they excluded the precise result of Junghans et al. We show that their statistical analysis is incorrect, due to a substantial underestimate of the experimental uncertainties, and leads to conclusions that are not supported by a proper analysis.Comment: submitted to Phys. Rev.

    Classical-path integral adaptive resolution in molecular simulation: towards a smooth quantum-classical coupling

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    Simulations that couple different classical molecular models in an adaptive way by changing the number of degrees of freedom on the fly, are available within reasonably consistent theoretical frameworks. The same does not occur when it comes to classical-quantum adaptivity. The main reason for this is the difficulty in describing a continuous transition between the two different kind of physical principles: probabilistic for the quantum and deterministic for the classical. Here we report the basic principles of an algorithm that allows for a continuous and smooth transition by employing the path integral description of atoms.Comment: 8 pages 4 figure

    C−\mathcal {C}-IBI: Targeting cumulative coordination within an iterative protocol to derive coarse-grained models of (multi-component) complex fluids

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    We present a coarse-graining strategy that we test for aqueous mixtures. The method uses pair-wise cumulative coordination as a target function within an iterative Boltzmann inversion (IBI) like protocol. We name this method coordination iterative Boltzmann inversion (C−\mathcal {C}-IBI). While the underlying coarse-grained model is still structure based and, thus, preserves pair-wise solution structure, our method also reproduces solvation thermodynamics of binary and/or ternary mixtures. Additionally, we observe much faster convergence within C−\mathcal {C}-IBI compared to IBI. To validate the robustness, we apply C−\mathcal {C}-IBI to study test cases of solvation thermodynamics of aqueous urea and a triglycine solvation in aqueous urea

    ParĂąmetros de qualidade de frutos de novos hĂ­bridos de abacaxizeiros desenvolvidos pela Embrapa Mandioca e Fruticultura.

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    O fruto do abacaxizeiro Ă© bastante apreciado e apresenta grande aceitação no mercado mundial em decorrĂȘncia de suas caracterĂ­sticas sensoriais e nutricionais. O programa de melhoramento genĂ©tico do abacaxizeiro da Embrapa Mandioca e Fruticultura desenvolve novos hĂ­bridos para atender Ă s expectativas deste mercado

    Impacto potencial das mudanças climåticas sobre as doenças do abacaxi no Brasil.

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    O abacaxizeiro e o clima; Doenças causadas por fungos e oomicetos; Doença causada por vírus; Doença abiótica

    Statistical Mechanics of Aggregation and Crystallization for Semiflexible Polymers

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    By means of multicanonical computer simulations, we investigate thermodynamic properties of the aggregation of interacting semiflexible polymers. We analyze a mesoscopic bead-stick model, where nonbonded monomers interact via Lennard-Jones forces. Aggregation turns out to be a process, in which the constituents experience strong structural fluctuations, similar to peptides in coupled folding-binding cluster formation processes. In contrast to a recently studied related proteinlike hydrophobic-polar heteropolymer model, aggregation and crystallization are separate processes for a homopolymer with the same small bending rigidity. Rather stiff semiflexible polymers form a liquid-crystal-like phase, as expected. In analogy to the heteropolymer study, we find that the first-order-like aggregation transition of the complexes is accompanied by strong system-size dependent hierarchical surface effects. In consequence, the polymer aggregation is a phase-separation process with entropy reduction.Comment: 5 pages, 3 figures, 1 tabl

    Progress of the Felsenkeller shallow-underground accelerator for nuclear astrophysics

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    Low-background experiments with stable ion beams are an important tool for putting the model of stellar hydrogen, helium, and carbon burning on a solid experimental foundation. The pioneering work in this regard has been done by the LUNA collaboration at Gran Sasso, using a 0.4 MV accelerator. In the present contribution, the status of the project for a higher-energy underground accelerator is reviewed. Two tunnels of the Felsenkeller underground site in Dresden, Germany, are currently being refurbished for the installation of a 5 MV high-current Pelletron accelerator. Construction work is on schedule and expected to complete in August 2017. The accelerator will provide intense, 50 uA, beams of 1H+, 4He+, and 12C+ ions, enabling research on astrophysically relevant nuclear reactions with unprecedented sensitivity.Comment: Submitted to the Proceedings of Nuclei in the Cosmos XIV, 19-24 June 2016, Niigata/Japa

    Qualidade de frutos de abacaxi pérola em função do tamanho e estådio de maturação na colheita.

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    Nos Ășltimos tempos consumidores tem sido mais rigorosos nas suas exigĂȘncias quanto aos padrĂ”es de qualidade dos alimentos, principalmente para consumo in natura, tendo em vista que as caracterĂ­sticas e a aparĂȘncia do produto sĂŁo fatores determinantes na comercialização (Bengozi et al., 2007)

    Experimental study of fragmentation products in the reactions 112Sn + 112Sn and 124Sn + 124Sn at 1 AGeV

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    Production cross-sections and longitudinal velocity distributions of the projectile-like residues produced in the reactions 112Sn + 112Sn and 124Sn + 124Sn both at an incident beam energy of 1 AGeV were measured with the high-resolution magnetic spectrometer, the Fragment Separator (FRS) of GSI. For both reactions the characteristics of the velocity distributions and nuclide production cross sections were determined for residues with atomic number Z ≄\geq 10. A comparison of the results of the two reactions is presented.Comment: 14 pages, 12 figure
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