443 research outputs found
The GRB-Supernova Connection
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
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- qubit in one Josephson junction
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- 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.
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-sulfonatoÂanilino)acetato-κO]copper(II) dihydrate
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-sulfonatoÂanilino)acetate (spia) ligand in a distorted square-pyramidal geometry. InterÂmolecular N—H⋯O and O—H⋯O hydrogen bonds, as well as π–π interÂactions 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 supraÂmolecular structure
Backreaction in Axion Monodromy, 4-forms and the Swampland
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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