Photoconduction and the electronic structure of silica nanowires embedded with gold nanoparticles

[[abstract]]Silica nanowires (SiOx-NWs) embedded with Au peapods have been studied by energy-filtered scanning transmission electron microscopy (EFTEM), O K- and Au L3-edge x-ray absorption near-edge structure (XANES), and extended x-ray absorption fine structure (EXAFS), x-ray emission spectroscopy (XES) and scanning photoelectron microscopy. XANES and XES data show that band gaps of Au-peapod-embedded and pure SiOx-NWs were 6.8 eV. In additional, XANES and EXAFS results indicate illumination-induced electron transfer from Au peapod to SiOx-NWs and does not show any feature attributable to the formation of Au-Si bonding in the Au peapod embedded in SiOx-NWs with or without illumination. Photoresponse and EFTEM measurements show that green light has more significant enhancement of photoconductivity than red and blue light due to surface plasmon resonance and suggest that transport of electrons across SiOx-NWs is via Mott-variable-range hopping mechanism through localized or defect states.[[incitationindex]]SCI[[booktype]]紙

Regularized Fine-grained Meta Face Anti-spoofing

Face presentation attacks have become an increasingly critical concern when face recognition is widely applied. Many face anti-spoofing methods have been proposed, but most of them ignore the generalization ability to unseen attacks. To overcome the limitation, this work casts face anti-spoofing as a domain generalization (DG) problem, and attempts to address this problem by developing a new meta-learning framework called Regularized Fine-grained Meta-learning. To let our face anti-spoofing model generalize well to unseen attacks, the proposed framework trains our model to perform well in the simulated domain shift scenarios, which is achieved by finding generalized learning directions in the meta-learning process. Specifically, the proposed framework incorporates the domain knowledge of face anti-spoofing as the regularization so that meta-learning is conducted in the feature space regularized by the supervision of domain knowledge. This enables our model more likely to find generalized learning directions with the regularized meta-learning for face anti-spoofing task. Besides, to further enhance the generalization ability of our model, the proposed framework adopts a fine-grained learning strategy that simultaneously conducts meta-learning in a variety of domain shift scenarios in each iteration. Extensive experiments on four public datasets validate the effectiveness of the proposed method.Comment: Accepted by AAAI 2020. Codes are available at https://github.com/rshaojimmy/AAAI2020-RFMetaFA

Natural orbits of atomic Cooper pairs in a nonuniform Fermi gas

We examine the basic mode structure of atomic Cooper pairs in an inhomogeneous Fermi gas. Based on the properties of Bogoliubov quasi-particle vacuum, the single particle density matrix and the anomalous density matrix share the same set of eigenfunctions. These eigenfunctions correspond to natural pairing orbits associated with the BCS ground state. We investigate these orbits for a Fermi gas in a spherical harmonic trap, and construct the wave function of a Cooper pair in the form of Schmidt decomposition. The issue of spatial quantum entanglement between constituent atoms in a pair is addressed.Comment: 14 pages, 4 figures, submitted to Phys. Rev.

Injection locking of spin-torque nano-oscillators

This journal issue contain selected papers from the Asia-Pacific Data Storage Conference (APDSC'13)We demonstrated the phase locking of a spin-torque oscillator (STO) to an alternating current (ac) using macrospin and micromagnetic simulations. We found that the locking properties of both approaches agree with each other. The phase difference between the STO and the injected ac stabilizes at ∆φ ≈ 90° and is not sensitive to the initial phase difference, which provides potential application of STO for microwave generation.published_or_final_versio

Electronic structure of the Fe-layer-catalyzed carbon nanotubes studied by x-ray-absorption spectroscopy

[[abstract]]X-ray-absorption near edge structure (XANES) measurements have been performed to investigate the local electronic structures of the Fe-catalyzed and stabilized carbon nanotubes (CNT) with various diameters. The intensities of the π∗- and σ∗-band and the interlayer-state features in the C K-edge XANES spectra of these CNTs vary with the diameter of the CNT. The white-line features at the C K- and Fe L3-edges suggest a strong hybridization between the C 2p and Fe 3d orbitals, which lead to an enhancement of the C K- and reduction of the Fe L3-edge features, respectively, indicative of a charge transfer from C 2p to Fe 3d orbitals. The Fe K-edge spectra reveal a p–d rehybridization effect that reduces p-orbital occupation at the Fe site.[[booktype]]紙