4,790 research outputs found

    Assessing seismic efficiency from scalar Moment-rates: an application to Mt. Etna volcano (Italy)

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    Here we propose an improved estimation of the scalar seismic (from instrumental and historical catalogues), geodetic and geologic moment-rates for the eastern flank of Mt. Etna. The estimated moment-rates have been compared in terms of seismic efficiency. Results show that all the calculated efficiency values are lower than 40%, i.e., the geodetic moment-rate estimations are generally larger than the seismic and the geologic ones. Although a number of reasons may account for the observed discrepancy, we are confident that a large amount of the deformation affecting the eastern flank occurs aseismically

    Study of the reaction pbar p -> phi phi from 1.1 to 2.0 GeV/c

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    A study has been performed of the reaction pbar p -> 4K using in-flight antiprotons from 1.1 to 2.0 GeV/c incident momentum interacting with a hydrogen jet target. The reaction is dominated by the production of a pair of phi mesons. The pbar p -> phi phi cross section rises sharply above threshold and then falls continuously as a function of increasing antiproton momentum. The overall magnitude of the cross section exceeds expectations from a simple application of the OZI rule by two orders of magnitude. In a fine scan around the xi/f_J(2230) resonance, no structure is observed. A limit is set for the double branching ratio B(xi -> pbar p) * B(xi -> phi phi) < 6e-5 for a spin 2 resonance of M = 2.235 GeV and Width = 15 MeV.Comment: 13 pages, 13 figures, 2 tables, Latex. To be published in Phys. Rev.

    Multiple myeloma exploits Jagged1 and Jagged2 to promote intrinsic and bone marrow-dependent drug resistance

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    Multiple myeloma is still incurable due to an intrinsic aggressiveness or, more frequently, to the interactions of malignant plasma cells with bone marrow microenvironment. Myeloma cells educate bone marrow cells to support neoplastic cell growth, survival, acquisition of drug resistance resulting in disease relapse. Myeloma microenvironment is characterized by Notch signaling hyperactivation due to the increased expression of Notch1 and 2 and the ligands Jagged1 and 2 in tumor cells. Notch activation influences myeloma cell biology and promotes the reprogramming of bone marrow stromal cells. In this work we demonstrate, by in vitro, ex vivo and using a zebrafish multiple myeloma model, that Jagged inhibition causes a decrease in both myeloma-intrinsic and stromal cell-induced resistance to currently used drugs, i.e. bortezomib, lenalidomide and melphalan. The molecular mechanism of drug resistance involves the chemokine system CXCR4/SDF1\u3b1. Myeloma cell-derived Jagged ligands trigger Notch activity in bone marrow stromal cells. These, in turn, secrete higher levels of SDF1\u3b1 in the bone marrow microenvironment increasing CXCR4 activation in myeloma cells, which is further potentiated by the concomitant increased expression of this receptor induced by Notch activation. Consistently with the augmented pharmacological resistance, SDF1\u3b1 boosts the expression of BCL2, Survivin and ABCC1. These results indicate that a Jagged-tailored approach may contribute to disrupting the pharmacological resistance due to intrinsic myeloma cell features or to the pathological interplay with bone marrow stromal cells and, conceivably, improve patients' response to standard-of-care therapies

    On the influence of the cosmological constant on gravitational lensing in small systems

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    The cosmological constant Lambda affects gravitational lensing phenomena. The contribution of Lambda to the observable angular positions of multiple images and to their amplification and time delay is here computed through a study in the weak deflection limit of the equations of motion in the Schwarzschild-de Sitter metric. Due to Lambda the unresolved images are slightly demagnified, the radius of the Einstein ring decreases and the time delay increases. The effect is however negligible for near lenses. In the case of null cosmological constant, we provide some updated results on lensing by a Schwarzschild black hole.Comment: 8 pages, 1 figure; v2: extended discussion on the lens equation, references added, results unchanged, in press on PR

    Measurement of Branching Fractions and Rate Asymmetries in the Rare Decays B -> K(*) l+ l-

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    In a sample of 471 million BB events collected with the BABAR detector at the PEP-II e+e- collider we study the rare decays B -> K(*) l+ l-, where l+ l- is either e+e- or mu+mu-. We report results on partial branching fractions and isospin asymmetries in seven bins of di-lepton mass-squared. We further present CP and lepton-flavor asymmetries for di-lepton masses below and above the J/psi resonance. We find no evidence for CP or lepton-flavor violation. The partial branching fractions and isospin asymmetries are consistent with the Standard Model predictions and with results from other experiments.Comment: 16 pages, 14 figures, accepted by Phys. Rev.

    Measurement of the mass and lifetime of the Ωb\Omega_b^- baryon

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    A proton-proton collision data sample, corresponding to an integrated luminosity of 3 fb1^{-1} collected by LHCb at s=7\sqrt{s}=7 and 8 TeV, is used to reconstruct 63±963\pm9 ΩbΩc0π\Omega_b^-\to\Omega_c^0\pi^-, Ωc0pKKπ+\Omega_c^0\to pK^-K^-\pi^+ decays. Using the ΞbΞc0π\Xi_b^-\to\Xi_c^0\pi^-, Ξc0pKKπ+\Xi_c^0\to pK^-K^-\pi^+ decay mode for calibration, the lifetime ratio and absolute lifetime of the Ωb\Omega_b^- baryon are measured to be \begin{align*} \frac{\tau_{\Omega_b^-}}{\tau_{\Xi_b^-}} &= 1.11\pm0.16\pm0.03, \\ \tau_{\Omega_b^-} &= 1.78\pm0.26\pm0.05\pm0.06~{\rm ps}, \end{align*} where the uncertainties are statistical, systematic and from the calibration mode (for τΩb\tau_{\Omega_b^-} only). A measurement is also made of the mass difference, mΩbmΞbm_{\Omega_b^-}-m_{\Xi_b^-}, and the corresponding Ωb\Omega_b^- mass, which yields \begin{align*} m_{\Omega_b^-}-m_{\Xi_b^-} &= 247.4\pm3.2\pm0.5~{\rm MeV}/c^2, \\ m_{\Omega_b^-} &= 6045.1\pm3.2\pm 0.5\pm0.6~{\rm MeV}/c^2. \end{align*} These results are consistent with previous measurements.Comment: 11 pages, 5 figures, All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-008.htm
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