524 research outputs found

    Strong magnetic field dependence of critical current densities and vortex activation energies in an anisotropic clean MgB2 thin film

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    We report the influence of two-band superconductivity on the flux creep and the critical current densities of a MgB2 thin film. The small magnetic penetration depth of lambda=50 +/- 10 nm at T=4 K is related to a clean pi-band. We find a high self-field critical current density J(C), which is strongly reduced with applied magnetic field, and attribute this to suppression of the superconductivity in the pi-band. The temperature dependence of the creep rate S (T) at low magnetic field can be explained by a simple Anderson-Kim mechanism. The system shows high pinning energies at low field that are strongly suppressed by high field. (C) 2014 Elsevier Ltd. All rights reserved.X1112Ysciescopu

    A Novel Cytoplasmic Protein with RNA-binding Motifs Is an Autoantigen in Human Hepatocellular Carcinoma

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    In hepatocellular carcinoma (HCC), autoantibodies to intracellular antigens are detected in 30–40% of patients. Patients with chronic hepatitis or liver cirrhosis develop HCC, and when this occurs, some patients exhibit autoantibodies of new specificities. It has been suggested that these novel autoantibody responses may be immune system reactions to proteins involved in transformation-associated cellular events. One HCC serum shown to contain antibodies to unidentified cellular antigens was used to immunoscreen a cDNA expression library, and a full length cDNA clone was isolated with an open reading frame encoding 556 amino acids with a predicted molecular mass of 62 kD. The 62-kD protein contained two types of RNA-binding motifs, the consensus sequence RNA–binding domain (CS-RBD) and four hnRNP K homology (KH) domains. This protein, provisionally called p62, has close identity (66–70%) to three other proteins at the amino acid sequence level, and all four proteins may belong to a family having CS-RBD in the NH2-terminal region and four KH domains in the mid-to-COOH– terminal region. The homologous proteins are: KH domain–containing protein overexpressed in cancer (Koc); zipcode binding protein, a protein which binds to a conserved nucleotide element in chicken β-actin mRNA (ZBP1); and a protein which binds to a promoter cis element in Xenopus laevis TFIIIA gene (B3). p62 protein is cytoplasmic in location, and autoantibodies were found in 21% of a cohort of HCC patients. Patients with chronic hepatitis and liver cirrhosis, conditions which are frequent precursors to HCC, were negative for these autoantibodies, suggesting that the immune response might be related to cellular events leading to transformation. However, the possible involvement of p62 autoantigen as a factor in the transformation process remains to be elucidated

    Observation of CR Anisotropy with ARGO-YBJ

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    The measurement of the anisotropies of cosmic ray arrival direction provides important informations on the propagation mechanisms and on the identification of their sources. In this paper we report the observation of anisotropy regions at different angular scales. In particular, the observation of a possible anisotropy on scales between \sim 10 ^{\circ} and \sim 30 ^{\circ} suggests the presence of unknown features of the magnetic fields the charged cosmic rays propagate through, as well as potential contributions of nearby sources to the total flux of cosmic rays. Evidence of new weaker few-degree excesses throughout the sky region 195195^{\circ}\leq R.A. 315\leq 315^{\circ} is reported for the first time.Comment: Talk given at 12th TAUP Conference 2011, 5-9 September 2011, Munich, German

    Global patterns of Joule heating in the high-latitude ionosphere

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    [1] A compiled empirical global Joule heating (CEJH) model is described in this study. This model can be used to study Joule heating patterns, Joule heating power, potential drop, and polar potential size in the high-latitude ionosphere and thermosphere, and their variations with solar wind conditions, geomagnetic activities, the solar EUV radiation, and the neutral wind. It is shown that the interplanetary magnetic field ( IMF) orientation and its magnitude, the solar wind speed, AL index, geomagnetic K-p index, and solar radio flux F-10.7 index are important parameters that control Joule heating patterns, Joule heating power, potential drop, and polar potential size. Other parameters, such as the solar wind number density (N-sw) and Earth's dipole tilt, do not significantly affect these quantities. It is also shown that the neutral wind can increase or reduce the Joule heating production, and its effectiveness mainly depends on the IMF orientation and its magnitude, the solar wind speed, AL index, K-p index, and F10.7 index. Our results indicate that for less disturbed solar wind conditions, the increase or reduction of the neutral wind contribution to the Joule heating is not significant compared to the convection Joule heating, whereas under extreme solar wind conditions, the neutral wind can significantly contribute to the Joule heating. Application of the CEJH model to the 16 July 2000 storm implies that the model outputs are basically consistent with the results from the AMIE mapping procedure. The CEJH model can be used to examine large-scale energy deposition during disturbed solar wind conditions and to study the dependence of the hemispheric Joule heating on the level of geomagnetic activities and the intensity of solar EUV radiation. This investigation enables us to predict global Joule heating patterns for other models in the high-latitude ionosphere and thermosphere in the sense of space weather forecasting.Publishe

    Observation of the cosmic ray moon shadowing effect with the ARGO-YBJ experiment

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    Cosmic rays are hampered by the Moon and a deficit in its direction is expected (the so-called Moon shadow). The Moon shadow is an important tool to determine the performance of an air shower array. Indeed, the westward displacement of the shadow center, due to the bending effect of the geomagnetic field on the propagation of cosmic rays, allows the setting of the absolute rigidity scale of the primary particles inducing the showers recorded by the detector. In addition, the shape of the shadow permits to determine the detector point spread function, while the position of the deficit at high energies allows the evaluation of its absolute pointing accuracy. In this paper we present the observation of the cosmic ray Moon shadowing effect carried out by the ARGO-YBJ experiment in the multi-TeV energy region with high statistical significance (55 standard deviations). By means of an accurate Monte Carlo simulation of the cosmic rays propagation in the Earth-Moon system, we have studied separately the effect of the geomagnetic field and of the detector point spread function on the observed shadow. The angular resolution as a function of the particle multiplicity and the pointing accuracy have been obtained. The primary energy of detected showers has been estimated by measuring the westward displacement as a function of the particle multiplicity, thus calibrating the relation between shower size and cosmic ray energy. The stability of the detector on a monthly basis has been checked by monitoring the position and the deficit of the Moon shadow. Finally, we have studied with high statistical accuracy the shadowing effect in the ''day/night’’ time looking for possible effect induced by the solar wind

    Highlights from the ARGO-YBJ experiment

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    The ARGO-YBJ experiment at YangBaJing in Tibet (4300 m a.s.l.) has been taking data with its full layout since October 2007. Here we present a few significant results obtained in gamma-ray astronomy and cosmic-ray physics. Emphasis is placed on the analysis of gamma-ray emission from point-like sources (Crab Nebula, MRK 421), on the preliminary limit on the antiproton/proton flux ratio, on the large-scale cosmic-ray anisotropy and on the proton–air cross-section. The performance of the detector is also discussed, and the perspectives of the experiment are outlined

    Kinase inhibit region of SOCS3 attenuates IL6-induced proliferation and astrocytic differentiation of neural stem cells via cross talk between signaling pathways

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    Aims: Efficiency of neural stem cells (NSCs) therapy for brain injury is restricted by astrogliosis around the damaged region, in which JAK2/STAT3 signaling plays a key role. The SOCS3 that can directly inhibit JAK/STAT3 pathway. Here, we investigated the effects of a fusion peptide that combined kinase inhibitory region (KIR) of SOCS3 and virus trans-activator of transcription (TAT) on biological behavior of cultured NSCs under inflammatory conditions. Methods: NSCs were isolated from embryonic brain of SD rats, TAT-KIR was synthesized, and penetration rate was evaluated by flow cytometry (FACS). CCK8, immunostaining, and FACS were used to detected of TAT-KIR on the proliferation of NSCs. The expressions of GFAP and β tubulin III positive cells induced by IL6 with/without TAT-KIR were examined by immunostaining and Western blotting to observe the NSCs differentiation, and the effect of TAT-KIR on signaling cross talk was observed by Western blotting. Results: Penetration rate of TAT-KIR into primary cultured NSCs was up to 94%. TAT-KIR did not affect the growth and viability of NSCs. It significantly reduced the NSCs proliferation that enhanced by IL-6 stimulation via blocking the cell cycle progression from the G0/G1 to S phase. In addition, TAT-KIR attenuated astrocytic differentiation and kept high level of neuronal differentiation derived from IL-6-induced NSCs. The fate of NSCs differentiation under inflammatory conditions was affected by TAT-KIR, which was associated with synchronous inhibition of STAT3 and AKT, while promoting JNK expression. Conclusion: TAT-KIR mimetic of SOCS3 could be a promising approach for brain repair via regulating the biological behaviors of exogenous NSCs
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