443 research outputs found

    The GRB-Supernova Connection

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    Long-duration gamma-ray bursts (GRBs) are believed to be produced by the core collapse of massive stars and hence to be connected with supernovae (SNe). Indeed, for four pairs of GRBs and SNe, spectroscopically confirmed connection has been firmly established. For more than a dozen of GRBs the SN signature (the `red bump') has been detected in the afterglow lightcurves. Based on the four pairs of GRBs and SNe with spectroscopically confirmed connection a tight correlation was found between the peak spectral energy of GRBs and the peak bolometric luminosity of the underlying SNe. The recent discovery of X-ray flash 080109 associated with a normal core-collapse SN 2008D confirmed this relation and extended the GRB-SN connection. Progress on the GRB-SN connection is briefly reviewed.Comment: 6 pages, 5 figures. To appear in the proceedings of "2008 Nanjing GRB conference", Nanjing, 23-27 June 200

    Robust Statistical Inference for Large-dimensional Matrix-valued Time Series via Iterative Huber Regression

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    Matrix factor model is drawing growing attention for simultaneous two-way dimension reduction of well-structured matrix-valued observations. This paper focuses on robust statistical inference for matrix factor model in the ``diverging dimension" regime. We derive the convergence rates of the robust estimators for loadings, factors and common components under finite second moment assumption of the idiosyncratic errors. In addition, the asymptotic distributions of the estimators are also derived under mild conditions. We propose a rank minimization and an eigenvalue-ratio method to estimate the pair of factor numbers consistently. Numerical studies confirm the iterative Huber regression algorithm is a practical and reliable approach for the estimation of matrix factor model, especially under the cases with heavy-tailed idiosyncratic errors . We illustrate the practical usefulness of the proposed methods by two real datasets, one on financial portfolios and one on the macroeconomic indices of China

    0-Ï€\pi qubit in one Josephson junction

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    Quantum states are usually fragile which makes quantum computation being not as stable as classical computation. Quantum correction codes can protect quantum states but need a large number of physical qubits to code a single logic qubit. Alternatively, the protection at the hardware level has been recently developed to maintain the coherence of the quantum information by using symmetries. However, it generally has to pay the expense of increasing the complexity of the quantum devices. In this work, we show that the protection at the hardware level can be approached without increasing the complexity of the devices. The interplay between the spin-orbit coupling and the Zeeman splitting in the semiconductor allows us to tune the Josephson coupling in terms of the spin degree of freedom of Cooper pairs, the hallmark of the superconducting spintronics. This leads to the implementation of the parity-protected 0-Ï€\pi superconducting qubit with only one highly transparent superconductor-semiconductor Josephson junction, which makes our proposal immune from the various fabrication imperfections.Comment: 5 pages, 4 figure

    MiRNA-145 increases therapeutic sensibility to gemcitabine treatment of pancreatic adenocarcinoma cells.

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    Pancreatic adenocarcinoma is one of the most leading causes of cancer-related deaths worldwide. Although recent advances provide various treatment options, pancreatic adenocarcinoma has poor prognosis due to its late diagnosis and ineffective therapeutic multimodality. Gemcitabine is the effective first-line drug in pancreatic adenocarcinoma treatment. However, gemcitabine chemoresistance of pancreatic adenocarcinoma cells has been a major obstacle for limiting its treatment effect. Our study found that p70S6K1 plays an important role in gemcitabine chemoresistence. MiR-145 is a tumor suppressor which directly targets p70S6K1 for inhibiting its expression in pancreatic adenocarcinoma, providing new therapeutic scheme. Our findings revealed a new mechanism underlying gemcitabine chemoresistance in pancreatic adenocarcinoma cells

    Bis(1,10-phenanthroline-κ2 N,N′)[2-(4-sulfonato­anilino)acetato-κO]copper(II) dihydrate

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    In the title compound, [Cu(C8H7NO5S)(C12H8N2)2]·2H2O, the CuII ion is coordinated by four N atoms from two 1,10-phenanthroline (phen) ligands and one O atom from a 2-(4-sulfonato­anilino)acetate (spia) ligand in a distorted square-pyramidal geometry. Inter­molecular N—H⋯O and O—H⋯O hydrogen bonds, as well as π–π inter­actions between phen ligands and between phen and spia ligands [centroid–centroid distances = 3.663 (3), 3.768 (3) and 3.565 (3) Å], result in a three-dimensional supra­molecular structure

    Backreaction in Axion Monodromy, 4-forms and the Swampland

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    Axion monodromy models can always be described in terms of an axion coupled to 3-form gauge fields with non-canonical kinetic terms. The presence of the saxions parametrising the kinetic metrics of the 3-form fields leads to backreaction effects in the inflationary dynamics. We review the case in which saxions backreact on the K\"ahler metric of the inflaton leading to a logarithmic scaling of the proper field distance at large field. This behaviour is universal in Type II string flux compactifications and consistent with a refinement of the Swampland Conjecture. The critical point at which this behaviour appears depends on the mass hierarchy between the inflaton and the saxions. However, in tractable compactifications, such a hierarchy cannot be realised without leaving the regime of validity of the effective theory, disfavouring transplanckian excursions in string theory.Comment: Proceedings prepared for the "Workshop on Geometry and Physics", November 2016, Ringberg Castl
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