7,839 research outputs found

    The political dimension of seasonal allocations: Developing a seasonal allocation strategy in a water-short system in Sri Lanka

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    Water allocation, Irrigation programs, Reservoirs, Participatory management, Farmer participation, Water rights, Irrigated farming, Rice, Water shortage, Farmers' attitudes, Farmer-agency interactions, Sri Lanka

    The determination and distribution of iodate in South Atlantic waters

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    A novel method has been developed for the precise determination of iodate in sea water and the technique has been applied to samples from two stations in the Argentine Basin and one station in the Angola Basin. The method involves acidification of the sea water sample in the presence of excess iodjde in order to form the tri-iodide ion and measurement of the absorbance of this ion in a spectrophotometric titration cell...

    The magnetic phase of the perovskite CaCrO3_3 studied with ÎĽ+\mu^{+}SR

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    We investigated the magnetic phase of the perovskite CaCrO3_3 by using the muon spin relaxation technique accompanied by susceptibility measurements. A thermal hysteresis loop is identified with a width of about 1 K at the transition temperature. Within the time scale of the muon lifetime, a static antiferromagnetic order is revealed with distinct multiple internal fields which are experienced in the muon interstitial sites below the phase-transition temperature, TN=90KT_N=90 K. Above TNT_N, lattice deformations are indicated by transverse-field muon-spin rotation and relaxation suggesting a magneto-elastic mechanism.Comment: 5 pages, 4 figures. Accepted for publication in PR

    Models of the distribution of 210Pb in a section across the North Equatorial Atlantic Ocean

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    The deficiency of 210Pb relative to 226Ra in the world\u27s deep ocean is well documented, and the overall residence time of 210Pb bas been calculated to be about 15-100 years. It has been assumed, generally, that the removal mechanism is one of in situ adsorption on settling particles, but Bacon et al. (1976) suggested that a boundary scavenging process with diffusive and advective fluxes of 210Pb from the interior ocean may be a significant factor...

    Fe I Oscillator Strengths for the Gaia-ESO Survey

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    The Gaia-ESO Public Spectroscopic Survey (GES) is conducting a large-scale study of multi-element chemical abundances of some 100 000 stars in the Milky Way with the ultimate aim of quantifying the formation history and evolution of young, mature and ancient Galactic populations. However, in preparing for the analysis of GES spectra, it has been noted that atomic oscillator strengths of important Fe I lines required to correctly model stellar line intensities are missing from the atomic database. Here, we present new experimental oscillator strengths derived from branching fractions and level lifetimes, for 142 transitions of Fe I between 3526 {\AA} and 10864 {\AA}, of which at least 38 are urgently needed by GES. We also assess the impact of these new data on solar spectral synthesis and demonstrate that for 36 lines that appear unblended in the Sun, Fe abundance measurements yield a small line-by-line scatter (0.08 dex) with a mean abundance of 7.44 dex in good agreement with recent publications.Comment: Accepted for publication in Mon. Not. R. Astron. So

    Complementarity and Young's interference fringes from two atoms

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    The interference pattern of the resonance fluorescence from a J=1/2 to J=1/2 transition of two identical atoms confined in a three-dimensional harmonic potential is calculated. Thermal motion of the atoms is included. Agreement is obtained with experiments [Eichmann et al., Phys. Rev. Lett. 70, 2359 (1993)]. Contrary to some theoretical predictions, but in agreement with the present calculations, a fringe visibility greater than 50% can be observed with polarization-selective detection. The dependence of the fringe visibility on polarization has a simple interpretation, based on whether or not it is possible in principle to determine which atom emitted the photon.Comment: 12 pages, including 7 EPS figures, RevTex. Submitted to Phys. Rev.

    Individual differences in working memory capacity predict benefits to memory from intention offloading

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    Research suggests that individuals with lower working memory have difficulty remembering to fulfil delayed intentions. The current study examined whether the ability to offload intentions onto the environment mitigated these deficits. Participants (N = 268) completed three versions of a delayed intention task with and without the use of reminders, along with three measures of working memory capacity. Results showed that individuals with higher working memory fulfilled more intentions when having to rely on their own memory, but this difference was eliminated when offloading was permitted. Individuals with lower working memory chose to offload more often, suggesting that they were less willing to engage in effortful maintenance of internal representations when given the option. Working memory was not associated with metacognitive confidence or optimal offloading choices based on point value. These findings suggest offloading may help circumvent capacity limitations associated with maintaining and remembering delayed intentions

    An approach to the use of hydrogen for commercial aircraft engines

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    This paper presents some results on the performance of hydrogen-based engines. In particular, the following aspects are addressed: benefits associated with specific fuel and energy consumption, net thrust, turbine entry temperature, and hardware changes needed in the upgrading process from kerosene to hydrogen. Hydrogen is a high-energy clean-burning fuel whose main combustion product is water vapour plus traces of nitrogen oxides. This fact suggests that, provided that the technology is available, the use of hydrogen could offer some opportunities for the environmentally friendly development and sustained growth of commercial aviation. The study has been performed in the frame of the Liquid Hydrogen Fuelled Aircraft – System Analysis (CRYOPLANE) project. This is a Fifth Framework Programme, supported by the European Commission, whose objective was to assess the feasibility of using hydrogen as a clean energy source for air transportation systems

    The Herbertsmithite Hamiltonian: ÎĽ\muSR measurements on single crystals

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    We present transverse field muon spin rotation/relaxation measurements on single crystals of the spin-1/2 kagome antiferromagnet Herbertsmithite. We find that the spins are more easily polarized when the field is perpendicular to the kagome plane. We demonstrate that the difference in magnetization between the different directions cannot be accounted for by Dzyaloshinksii-Moriya type interactions alone, and that anisotropic axial interaction is present.Comment: 8 pages, 3 figures, accepted to JPCM special issue on geometrically frustrated magnetis

    Sediment trap experiments in the deep North Atlantic: Isotopic and elemental fluxes

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    We have carried out sediment trap experiments at sites in the Sargasso Sea (S2) and in the Atlantic off Barbados (E) to determine the mass flux and chemical composition of material sinking to the sea floor…
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