8,792 research outputs found

    Lie groupoids and algebroids applied to the study of uniformity and homogeneity of material bodies

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    A Lie groupoid, called \textit{material Lie groupoid}, is associated in a natural way to any elastic material. The corresponding Lie algebroid, called \textit{material algebroid}, is used to characterize the uniformity and the homogeneity properties of the material. The relation to previous results in terms of GG-structures is discussed in detail. An illustrative example is presented as an application of the theory

    Nuclear effects in neutrino and antineutrino CCQE scattering at MINERvA kinematics

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    We compare the charged-current quasielastic neutrino and antineutrino observables obtained in two different nuclear models, the phenomenological SuperScaling Approximation and the Relativistic Mean Field approach, with the recent data published by the MINERvA Collaboration. Both models provide a good description of the data without the need of an ad hoc increase in the mass parameter in the axial-vector dipole form factor. Comparisons are also made with the MiniBooNE results where different conclusions are reached.Comment: 6 pages, 7 figures, Accepted for publication in Physical Review

    Impact of low-energy nuclear excitations on neutrino-nucleus scattering at MiniBooNE and T2K kinematics

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    [Background] Meticulous modeling of neutrino-nucleus interactions is essential to achieve the unprecedented precision goals of present and future accelerator-based neutrino-oscillation experiments. [Purpose] Confront our calculations of charged-current quasielastic cross section with the measurements of MiniBooNE and T2K, and to quantitatively investigate the role of nuclear-structure effects, in particular, low-energy nuclear excitations in forward muon scattering. [Method] The model takes the mean-field (MF) approach as the starting point, and solves Hartree-Fock (HF) equations using a Skyrme (SkE2) nucleon-nucleon interaction. Long-range nuclear correlations are taken into account by means of the continuum random-phase approximation (CRPA) framework. [Results] We present our calculations on flux-folded double differential, and flux-unfolded total cross sections off 12^{12}C and compare them with MiniBooNE and (off-axis) T2K measurements. We discuss the importance of low-energy nuclear excitations for the forward bins. [Conclusions] The CRPA predictions describe the gross features of the measured cross sections. They underpredict the data (more in the neutrino than in the antineutrino case) because of the absence of processes beyond pure quasielastic scattering in our model. At very forward muon scattering, low-energy nuclear excitations (ω<\omega < 50 MeV) account for nearly 50% of the flux-folded cross section.Comment: 8 pages, 9 figures. Version published in Physical Review

    Membrane protein Oca3 is essential to keep structural integrity of mitochondria and endoplasmic reticulum

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    Mitochondrial function is tightly conserved through evolution since it becomes essential for the fitness of any eukaryotic cell. Defective function of this organelle represents the cellular basis of some severe diseases in humans. Thus, the characterization of genes involved in the correct mitochondrial structure and function is critical to understand and treating these diseases. In our laboratory, using the fission yeast as a model, we are characterising the function of oca3 gene, the ortholog of EMC2 gene in human. This gene is predicted to be a member of the ER membrane protein complex involved in the mitochondrion-endoplasmic reticulum membrane tethering1. We find the protein in the non-aqueous phase in cell extracts and Oca3-mCherry tagging actually decorates most cell membranes. Oca3 over-expression cause lethality2 and the gene deletion becomes cold-sensitive. In both situations aberrant mitochondria aggregations are observed and endoplasmic reticulum seems disorganised. Interestingly, addition of Tween20 restores the viability of oca3 deletion at low temperature. This result suggests that Oca3 may have a role in membrane fluidity homeostasis. In addition to this, we will analyse different gene interaction between some of the EMC complex members to clarify both, the importance of Oca3 for the complex and the importance of the complex itself for the cell

    Abundant Z-cyanomethanimine in the interstellar medium: paving the way to the synthesis of adenine

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    We report the first detection in the interstellar medium of the Z-isomer of cyanomethanimine (HNCHCN), an HCN dimer proposed as precursor of adenine. We identified six transitions of Z-cyanomethanimine, along with five transitions of E-cyanomethanimine, using IRAM 30m observations towards the Galactic Center quiescent molecular cloud G+0.693. The Z-isomer has a column density of (2.0±\pm0.6)×\times1014^{14} cm2^{-2} and an abundance of 1.5×\times109^{-9}. The relative abundance ratio between the isomers is [Z/E]\sim6. This value cannot be explained by the two chemical formation routes previously proposed (gas-phase and grain surface), which predicts abundances ratios between 0.9 and 1.5. The observed [Z/E] ratio is in good agreement with thermodynamic equilibrium at the gas kinetic temperature (130-210 K). Since isomerization is not possible in the ISM, the two species may be formed at high temperature. New chemical models, including surface chemistry on dust grains and gas-phase reactions, should be explored to explain our findings. Whatever the formation mechanism, the high abundance of Z-HNCHCN shows that precursors of adenine are efficiently formed in the ISM.Comment: Accepted in Monthly Notices of the Royal Astronomical Society Letter
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