686 research outputs found

    Agricultural biodiversity is essential for a sustainable improvement in food and nutrition security

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    Agricultural biodiversity has hitherto been valued almost exclusively as a source of traits that can be used in scientific breeding programs to improve the productivity of crop varieties and livestock breeds. We argue that it can make a far greater contribution to increased productivity. In particular, a wider deployment of agricultural biodiversity is an essential component in the sustainable delivery of a more secure food supply. Diversity of kingdoms, species and genepools can increase the productivity of farming systems in a range of growing conditions, and more diverse farming systems are also generally more resilient in the face of perturbations, thus enhancing food security. Diversity can maintain and increase soil fertility and mitigate the impact of pests and diseases. Diversity of diet, founded on diverse farming systems, delivers better nutrition and greater health, with additional benefits for human productivity and livelihoods. Agricultural biodiversity will also be absolutely essential to cope with the predicted impacts of climate change, not simply as a source of traits but as the underpinnings of more resilient farm ecosystems. Many of the benefits of agricultural biodiversity are manifested at different ecological and human scales, and cut across political divisions, requiring a cross-sectoral approach to reassess the role of agricultural biodiversity in sustainable and secure food production

    The pion-pion Interaction in the rho Channel in Finite Volume

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    The aim of this paper is to investigate an efficient strategy that allows to obtain pi-pi phase shifts and rho meson properties from QCD lattice data with high precision. For this purpose we evaluate the levels of the pi-pi system in the rho channel in finite volume using chiral unitary theory. We investigate the dependence on the pi mass and compare with other approaches which use QCD lattice calculations and effective theories. We also illustrate the errors induced by using the conventional Luscher approach instead of a more accurate one recently developed that takes into account exactly the relativistic two meson propagators. Finally we make use of this latter approach to solve the inverse problem, getting pi-pi phase shifts from "synthetic" lattice data, providing an optimal strategy and showing which accuracy is needed in these data to obtain the ρ\rho properties with a desired accuracy.Comment: 16 pages, 13 figures, 1 table, substantially modified with practical examples of use to lattice researchers, new comments and references adde

    Extracting Scattering Phase-Shifts in Higher Partial-Waves from Lattice QCD Calculations

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    L\"uscher's method is routinely used to determine meson-meson, meson-baryon and baryon-baryon s-wave scattering amplitudes below inelastic thresholds from Lattice QCD calculations - presently at unphysical light-quark masses. In this work we review the formalism and develop the requisite expressions to extract phase-shifts describing meson-meson scattering in partial-waves with angular-momentum l<=6 and l=9. The implications of the underlying cubic symmetry, and strategies for extracting the phase-shifts from Lattice QCD calculations, are presented, along with a discussion of the signal-to-noise problem that afflicts the higher partial-waves.Comment: 79 pages, 41 figure

    A role for TSPO in mitochondrial Ca2+ homeostasis and redox stress signaling

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    The 18 kDa translocator protein TSPO localizes on the outer mitochondrial membrane (OMM). Systematically overexpressed at sites of neuroinflammation it is adopted as a biomarker of brain conditions. TSPO inhibits the autophagic removal of mitochondria by limiting PARK2-mediated mitochondrial ubiquitination via a peri-organelle accumulation of reactive oxygen species (ROS). Here we describe that TSPO deregulates mitochondrial Ca2+ signaling leading to a parallel increase in the cytosolic Ca2+ pools that activate the Ca2+-dependent NADPH oxidase (NOX) thereby increasing ROS. The inhibition of mitochondrial Ca2+ uptake by TSPO is a consequence of the phosphorylation of the voltage-dependent anion channel (VDAC1) by the protein kinase A (PKA), which is recruited to the mitochondria, in complex with the Acyl-CoA binding domain containing 3 (ACBD3). Notably, the neurotransmitter glutamate, which contributes neuronal toxicity in age-dependent conditions, triggers this TSPO-dependent mechanism of cell signaling leading to cellular demise. TSPO is therefore proposed as a novel OMM-based pathway to control intracellular Ca2+ dynamics and redox transients in neuronal cytotoxicity

    Electromagnetic corrections to light hadron masses

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    At the precision reached in current lattice QCD calculations, electromagnetic effects are becoming numerically relevant. We will present preliminary results for electromagnetic corrections to light hadron masses, based on simulations in which a U(1)\mathrm{U}(1) degree of freedom is superimposed on Nf=2+1N_f=2+1 QCD configurations from the BMW collaboration.Comment: 7 pages, 2 figures, The XXVIII International Symposium on Lattice Field Theory, June 14-19,2010, Villasimius, Sardinia Ital

    Rho decay width from the lattice

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    While the masses of light hadrons have been extensively studied in lattice QCD simulations, there exist only a few exploratory calculations of the strong decay widths of hadronic resonances. We will present preliminary results of a computation of the rho meson width obtained using Nf=2+1N_f=2+1 flavor simulations. The work is based on L\"uscher's formalism and its extension to moving frames.Comment: The XXVIII International Symposium on Lattice Field Theory, June 14-19,2010, Villasimius, Sardinia Ital

    Standard-model prediction for direct CP violation in KππK\to\pi\pi decay

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    We report the first lattice QCD calculation of the complex kaon decay amplitude A0A_0 with physical kinematics, using a 323×6432^3\times 64 lattice volume and a single lattice spacing aa, with 1/a=1.3784(68)1/a= 1.3784(68) GeV. We find Re(A0)=4.66(1.00)(1.26)×107(A_0) = 4.66(1.00)(1.26) \times 10^{-7} GeV and Im(A0)=1.90(1.23)(1.08)×1011(A_0) = -1.90(1.23)(1.08) \times 10^{-11} GeV, where the first error is statistical and the second systematic. The first value is in approximate agreement with the experimental result: Re(A0)=3.3201(18)×107(A_0) = 3.3201(18) \times 10^{-7} GeV while the second can be used to compute the direct CP violating ratio Re(ε/ε)=1.38(5.15)(4.59)×104(\varepsilon'/\varepsilon)=1.38(5.15)(4.59)\times 10^{-4}, which is 2.1σ2.1\sigma below the experimental value 16.6(2.3)×10416.6(2.3)\times 10^{-4}. The real part of A0A_0 is CP conserving and serves as a test of our method while the result for Re(ε/ε)(\varepsilon'/\varepsilon) provides a new test of the standard-model theory of CP violation, one which can be made more accurate with increasing computer capability.Comment: 9 pages, 3 figures. Updated to match published versio
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