530 research outputs found

    Summary booklet of the global strategy for the conservation and use of Musa genetic resources : A consultative document prepared by the Global Musa Genetic Resources Network (MusaNet)

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    This publication summarizes the Global Strategy for the Conservation and Use of Musa Genetic Resources

    SAGA: A project to automate the management of software production systems

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    The Software Automation, Generation and Administration (SAGA) project is investigating the design and construction of practical software engineering environments for developing and maintaining aerospace systems and applications software. The research includes the practical organization of the software lifecycle, configuration management, software requirements specifications, executable specifications, design methodologies, programming, verification, validation and testing, version control, maintenance, the reuse of software, software libraries, documentation, and automated management

    Supplying new cocoa planting material to farmers: a review of propagation methodologies

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    The review, coordinated by Bioversity International, presents an impartial, evidence-based review of cacao propagation methods, to serve as a basis for the assessment and implementation of strategies for providing farmers with quality planting materials, adapted to current and future needs (cultural, institutional, technical, environmental and financial). It describes the various propagation methods available for the production and supply of large numbers of cacao plants to growers. It is hoped that the result of the efforts of the key authors provides a basis to build on for case-specific recommendations. As the supply of new improved planting material to farmers is at the heart of improving cocoa productivity and modernizing the crop, we hope that the information in the review will make its way into national cocoa plans, and help to make cocoa farming more attractive and more sustainable

    Isotropic three-dimensional gap in the iron-arsenide superconductor LiFeAs from directional heat transport measurements

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    The thermal conductivity k of the iron-arsenide superconductor LiFeAs (Tc ~ 18K) was measured in single crystals at temperatures down to T~50mK and in magnetic fields up to H=17T, very close to the upper critical field Hc2~18T. For both directions of the heat current, parallel and perpendicular to the tetragonal c-axis, a negligible residual linear term k/T is found as T ->0, revealing that there are no zero-energy quasiparticles in the superconducting state. The increase in k with magnetic field is the same for both current directions and it follows closely the dependence expected for an isotropic superconducting gap. There is no evidence of multi-band character, whereby the gap would be different on different Fermi-surface sheets. These findings show that the superconducting gap in LiFeAs is isotropic in 3D, without nodes or deep minima anywhere on the Fermi surface. Comparison with other iron-pnictide superconductors suggests that a nodeless isotropic gap is a common feature at optimal doping (maximal Tc).Comment: 4 pages, 3 figure

    Continuous manganese delivery via osmotic pumps for manganese-enhanced mouse MRI does not impair spatial learning but leads to skin ulceration

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    Manganese-enhanced magnetic resonance imaging (MEMRI) is a widely used technique in rodent neuroimaging studies. Traditionally, Mn2+ is delivered to animals via a systemic injection; however, this can lead to toxic effects at high doses. Recent studies have shown that subcutaneously implanted mini-osmotic pumps can be used to continuously deliver manganese chloride (MnCl2), and that they produce satisfactory contrast while circumventing many of the toxic side effects. However, neither the time-course of signal enhancement nor the effect of continuous Mn2+ delivery on behaviour, particularly learning and memory, have been well-characterized. Here, we investigated the effect of MnCl2 dose and route of administration on a) spatial learning in the Morris Water Maze and b) tissue signal enhancement in the mouse brain. Even as early as 3 days after pump implantation, infusion of 25–50 mg/kg/day MnCl2 via osmotic pump produced signal enhancement as good as or better than that achieved 24 h after a single 50 mg/kg intraperitoneal injection. Neither route of delivery nor MnCl2 dose adversely affected spatial learning and memory on the water maze. However, especially at higher doses, mice receiving MnCl2 via osmotic pumps developed skin ulceration which limited the imaging window. With these findings, we provide recommendations for route and dose of MnCl2 to use for different study designs

    Evidence for a small hole pocket in the Fermi surface of underdoped YBa2Cu3Oy

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    The Fermi surface of a metal is the fundamental basis from which its properties can be understood. In underdoped cuprate superconductors, the Fermi surface undergoes a reconstruction that produces a small electron pocket, but whether there is another, as yet undetected portion to the Fermi surface is unknown. Establishing the complete topology of the Fermi surface is key to identifying the mechanism responsible for its reconstruction. Here we report the discovery of a second Fermi pocket in underdoped YBa2Cu3Oy, detected as a small quantum oscillation frequency in the thermoelectric response and in the c-axis resistance. The field-angle dependence of the frequency demonstrates that it is a distinct Fermi surface and the normal-state thermopower requires it to be a hole pocket. A Fermi surface consisting of one electron pocket and two hole pockets with the measured areas and masses is consistent with a Fermi-surface reconstruction caused by the charge-density-wave order observed in YBa2Cu3Oy, provided other parts of the reconstructed Fermi surface are removed by a separate mechanism, possibly the pseudogap.Comment: 23 pages, 5 figure

    Significant fatigue life enhancement in multiscale doubly-modified fiber/epoxy nanocomposites with graphene nanoplatelets and reduced-graphene oxide

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    ABSTRACT: We report the fatigue behavior of a novel multiscale fiberglass/epoxy composite modified with reduced-graphene oxide (rGO) and graphene nanoplatelets (GNP). A novel and cost-effective fabrication method based on vacuum assisted resin transfer molding (VARTM) method was used for manufacturing the composite laminates. Morphological and mechanical analysis of composites showed a successful dispersion of nano-fillers and a remarkable improvement in fatigue life of the nanocomposites. The experimental results revealed that all rGO concentrations resulted in a significant increase in fatigue life of the nanocomposites. These enhancements can be explained by the creation of stronger links between the nanoparticles fiberglass and epoxy. The experimental results also showed that lower concentrations of GNPs lead to an increase in fatigue life of nanocomposites; however, a decrease in their fatigue life can be seen at higher loadings

    2-Methyl-3-[(4-methyl­phen­yl)sulfon­yl­oxy]-2-{[(4-methyl­phen­yl)sulfon­yloxy]meth­yl}propyl 4-methyl­benzene­sulfonate

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    The title mol­ecule, C26H30O9S3, adopts an extended conformation whereby two approximately parallel benzene rings [dihedral angle = 8.32 (10)°] are orientated in opposite directions along the pseudo-threefold axis through the central quaternary C atom, while a third ring occupies a position mid-way and face-on to these rings [dihedral angles = 82.28 (10) and 78.81 (7)°]. The crystal packing is dominated by C—H⋯O contacts and π–π inter­actions [ring centroid distance = 3.6902 (12) Å]
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