25,053 research outputs found

    Site evaluation for laser satellite-tracking stations

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    Twenty-six locations for potential laser satellite-tracking stations, four of them actually already occupied in this role, are reviewed in terms of their known local and regional geology and geophysics. The sites are also considered briefly in terms of weather and operational factors. Fifteen of the sites qualify as suitable for a stable station whose motions are likely to reflect only gross plate motion. The others, including two of the present laser station sites (Arequipa and Athens), fail to qualify unless extra monitoring schemes can be included, such as precise geodetic surveying of ground deformation

    Neutron star matter in the quark-meson coupling model in strong magnetic fields

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    The effects of strong magnetic fields on neutron star matter are investigated in the quark-meson coupling (QMC) model. The QMC model describes a nuclear many-body system as nonoverlapping MIT bags in which quarks interact through self-consistent exchange of scalar and vector mesons in the mean-field approximation. The results of the QMC model are compared with those obtained in a relativistic mean-field (RMF) model. It is found that quantitative differences exist between the QMC and RMF models, while qualitative trends of the magnetic field effects on the equation of state and composition of neutron star matter are very similar.Comment: 16 pages, 4 figure

    About Detecting CP-Violating Processes in J/\psi\to \KzKzb Decay

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    Questions about detecting CP-violating decay process of J/ψ→K0Kˉ0→KSKSJ/\psi\to K^0\bar{K}^0\to K_SK_S are discussed. Possible background and material regeneration effect are analyzed. The discussion can be directly extended to other vector quarkonium decays, like Υ\Upsilon, ψ(2S)\psi (2S) and ϕ→KSKS\phi\to K_S K_S.Comment: 5 pages, 2 figures, Late

    Quasi-classical determination of the in-plane magnetic field phase diagram of superconducting Sr_2RuO_4

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    We have carried out a determination of the magnetic-field-temperature (H-T) phase diagram for realistic models of the high field superconducting state of tetragonal Sr_2RuO_4 with fields oriented in the basal plane. This is done by a variational solution of the Eilenberger equations.This has been carried for spin-triplet gap functions with a {\bf d}-vector along the c-axis (the chiral p-wave state) and with a {\bf d}-vector that can rotate easily in the basal plane. We find that, using gap functions that arise from a combination of nearest and next nearest neighbor interactions, the upper critical field can be approximately isotropic as the field is rotated in the basal plane. For the chiral {\bf d}-vector, we find that this theory generically predicts an additional phase transition in the vortex state. For a narrow range of parameters, the chiral {\bf d}-vector gives rise to a tetracritical point in the H-T phase diagram. When this tetracritical point exists, the resulting phase diagram closely resembles the experimentally measured phase diagram for which two transitions are only observed in the high field regime. For the freely rotating in-plane {\bf d}-vector, we also find that additional phase transition exists in the vortex phase. However, this phase transition disappears as the in-plane {\bf d}-vector becomes weakly pinned along certain directions in the basal plane.Comment: 12 pages, 8 figure

    Elasticity of highly cross-linked random networks

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    Starting from a microscopic model of randomly cross-linked particles with quenched disorder, we calculate the Laudau-Wilson free energy S for arbitrary cross-link densities. Considering pure shear deformations, S takes the form of the elastic energy of an isotropic amorphous solid state, from which the shear modulus can be identified. It is found to be an universal quantity, not depending on any microscopic length-scales of the model.Comment: 6 pages, 5 figure

    The protection of glycyrrhetinic acid (GA) towards acetaminophen (APAP)-induced toxicity partially through fatty acids metabolic pathway

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    Background: Acetaminophen (APAP)-induced liver toxicity remains the key factor limiting the clinical application of APAP, and herbs are the important sources for isolation of compounds preventing APAP-induced toxicity.Aims: To investigate the protection mechanism of glycyrrhetinic acid towards APAP-induced liver damage using metabolomics method.Methods: APAP-induced liver toxicity model was made through intraperitoneal injection (i.p.) of APAP (400 mg/kg). Glycyrrhetinic acid was dissolved in corn oil, and intraperitoneal injection (i.p.) of glycyrrhetinic acid (500 mg/kg body weight) was performed for 20 days before the injection of APAP. UPLC-ESI-QTOF MS was employed to analyze the metabolomic profile of serum samples.Results: The pre-treatment of glycyrrhetinic acid significantly protected APAP-induced toxicity, indicated by the histology of liver, the activity of ALT and AST. Metabolomics showed that the level of   palmtioylcarnitine and oleoylcarnitine significantly increased in serum of APAP-treated mice, and the pre-treatment with GA can prevent this elevation of these two fatty acid-carnitines.Conclusion: Reversing the metabolism pathway of fatty acid is an important mechanism for the protection of glycyrrhetinic acid towards acetaminophen-induced liver toxicity.Keywords: Glycyrrhetinic acid (GA), acetaminophen (APAP), metabolomics, fatty aci

    The Alignment between Satellites and Central Galaxies: Theory vs. Observations

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    Recent studies have shown that the distribution of satellite galaxies is preferentially aligned with the major axis of their central galaxy. The strength of this alignment has been found to depend strongly on the colours of the satellite and central galaxies, and only weakly on the mass of the halo in which the galaxies reside. In this paper we study whether these alignment signals, and their dependence on galaxy and halo properties, can be reproduced in a hierarchical structure formation model of a Λ\LambdaCDM concordance cosmology. To that extent we use a large NN-body simulation which we populate with galaxies following a semi-analytical model for galaxy formation. We find that if the orientation of the central galaxy is perfectly aligned with that of its dark matter halo, then the predicted central-satellite alignment signal is much stronger than observed. If, however, the minor axis of a central galaxy is perfectly aligned with the angular momentum vector of its dark matter halo, we can accurately reproduce the observed alignment strength as function of halo mass and galaxy color. Although this suggests that the orientation of central galaxies is governed by the angular momentum of their dark matter haloes, we emphasize that any other scenario in which the minor axes of central galaxy and halo are misaligned by ∼40∘\sim 40^{\circ} (on average) will match the data equally well. Finally, we show that dependence of the alignment strength on the color of the central galaxy is most likely an artefact due to interlopers in the group catalogue. The dependence on the color of the satellite galaxies, on the other hand, is real and owes to the fact that red satellites are associated with subhaloes that were more massive at their time of accretion.Comment: 13 Pages, 10 Figures, one figure replaced. added in discussion about comparison with others results, Updated version to match accepted version to MNRA
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