21,869 research outputs found
Superfluid response in electron-doped cuprate superconductors
We propose a weakly coupled two-band model with pairing
symmetry to account for the anomalous temperature dependence of superfluid
density in electron-doped cuprate superconductors. This model gives a
unified explanation to the presence of a upward curvature in near
and a weak temperature dependence of in low temperatures. Our
work resolves a discrepancy in the interpretation of different experimental
measurements and suggests that the pairing in electron-doped cuprates has
predominately symmetry in the whole doping range.Comment: 4 pages, 3 figures, title changed and references adde
Automatic facial expression tracking for 4D range scans
This paper presents a fully automatic approach of spatio-temporal facial expression tracking for 4D range scans without any manual interventions (such as specifying landmarks). The approach consists of three steps: rigid registration, facial model reconstruction, and facial expression tracking. A Scaling Iterative Closest Points (SICP) algorithm is introduced to compute the optimal rigid registration between a template facial model and a range scan with consideration of the scale problem. A deformable model, physically based on thin shells, is proposed to faithfully reconstruct the facial surface and texture from that range data. And then the reconstructed facial model is used to track facial expressions presented in a sequence of range scans by the deformable model
GeV photons from up-scattering of supernova shock breakout X-rays by an outside GRB jet
Shock breakout X-ray emission has been reported for the first time from a
supernova connected with a gamma-ray burst, namely GRB060218/SN2006aj. The
gamma-ray emission and the power-law decaying X-ray afterglow are ascribed to a
highly relativistic jet, while the thermal soft X-rays are thought to be
produced when the radiation-dominated shock breaks from the optically thick
stellar wind. We study the inverse Compton emission of the breakout thermal
soft X-rays scattered by relativistic electrons in the jet forward shock, which
is expected to be at larger radii than the breakout shock. This IC emission
produces sub-GeV to GeV photons, which may be detectable by GLAST. The
detection of such GeV photons simultaneously with the supernova shock breakout
emission would give evidence for the presence of a GRB jet ahead of the shock
while the shock is breaking out. The anisotropic scattering between the X-rays
and relativistic electrons may lead to large angle emission outside of the jet
opening angle. This has implications for the detection of GeV photons from
burstless type Ib/c hypernova shock breakout, which due to its more isotropic
emission might be observed with wide-field X-ray cameras such as LOBSTER.Comment: accepted for publication in ApJ Letters, 4 emulateapj pages, no
figure
Optimizing Hartree-Fock orbitals by the density-matrix renormalization group
We have proposed a density-matrix renormalization group (DMRG) scheme to
optimize the one-electron basis states of molecules. It improves significantly
the accuracy and efficiency of the DMRG in the study of quantum chemistry or
other many-fermion system with nonlocal interactions. For a water molecule, we
find that the ground state energy obtained by the DMRG with only 61 optimized
orbitals already reaches the accuracy of best quantum Monte Carlo calculation
with 92 orbitals.Comment: published version, 4 pages, 4 figure
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