A Color Image Watermarking Scheme Resistant against Geometrical Attacks

The geometrical attacks are still a problem for many digital watermarking algorithms at present. In this paper, we propose a watermarking algorithm for color images resistant to geometrical distortions (rotation and scaling). The singular value decomposition is used for watermark embedding and extraction. The log-polar map- ping (LPM) and phase correlation method are used to register the position of geometrical distortion suffered by the watermarked image. Experiments with different kinds of color images and watermarks demonstrate that the watermarking algorithm is robust to common image processing attacks, especially geometrical attacks

Effect of dietary betaine supplementation on mRNA level of lipogenesis genes and on promoter CpG methylation of fatty acid synthase (FAS) gene in laying hens

Our aims are to determine the effects of dietary betaine supplementation on growth performance, percentage of abdominal fat, ratio of liver to body weight, mRNA expression levels of acetyl-CoA carboxylase (ACC), fat acid synthase (FAS) and adipose differentiation-related protein (ADRP) genes in the abdominal fat of hens. In addition, promoter DNA methylation patterns of FAS gene were also analyzed by bisulfite sequencing. A total 120 of Hy-Line White laying hens were randomly divided into four diet groups with supplemented betaine of 0, 0.04, 0.06 and 0.08%, respectively. At 180 old days of age, the significant difference in egg production was observed between the control and 0.08% betaine diet group (P < 0.05). The FAS mRNA abundance was increased in the abdominal adipose of hens receiving 0.08% betaine compared to the hens receiving control diet with no betaine (P < 0.05). However, supplementation of betaine had no significant effect on FAS expression level in 165-day-old hens. The ACC and ADRP gene expression levels were not significantly affected by betaine at either 165 or 180-day-old hens (P>0.05). Furthermore, the overall GpG methylation patterns at the FAS gene promoter region ranging from −961 to −749 were not significantly different among all groups in 180-day-old hens (P > 0.05), CpG methylation mainly occur from 1st to 5th sites. This study suggests that betaine could regulate lipogenesis of laying chickens by affecting the transcription of FAS genes, and that DNA methylation at some CpG dinucleotides may play a role in regulating FAS gene expression.Key words: Betaine, CpG methylation, gene expression, laying hen, lipogenesis genes

Fully gapped superconducting state in Au2Pb: a natural candidate for topological superconductor

We measured the ultra-low-temperature specific heat and thermal conductivity of Au$_2$Pb single crystal, a possible three-dimensional Dirac semimetal with a superconducting transition temperature $T_c \approx$ 1.05 K. The electronic specific heat can be fitted by a two-band s-wave model, which gives the gap amplitudes $\Delta_1$(0)/$k_BT_c$ = 1.38 and $\Delta_2$(0)/$k_BT_c$ = 5.25. From the thermal conductivity measurements, a negligible residual linear term $\kappa_0/T$ in zero field and a slow field dependence of $\kappa_0/T$ at low field are obtained. These results suggest that Au$_2$Pb has a fully gapped superconducting state in the bulk, which is a necessary condition for topological superconductor if Au$_2$Pb is indeed one.Comment: 6 pages, 4 figure

Universal conductance fluctuation of mesoscopic systems in the metal-insulator crossover regime

We report a theoretical investigation on conductance fluctuation of mesoscopic systems. Extensive numerical simulations on quasi-one-dimensional, two-dimensional, and quantum dot systems with different symmetriescircular orthogonal ensemble, circular unitary ensemble (CUE), and 〔circular symplectic ensemble (CSE)〕indicate that the conductance fluctuation can reach a universal value in the crossover regime for systems with CUE and CSE symmetries. The conductance distribution is found to be a universal function from diffusive to localized regimes that depends only on the average conductance, dimensionality, and symmetry of the system. The numerical solution of DMPK equation agrees with our result in quasi-one dimension. Our numerical results in two dimensions suggest that this universal conductance fluctuation is related to the metal-insulator transition. In the localized regime with average conductance <0.3, the conductance distribution seems to be superuniversal independent of dimensionality and symmetry.published_or_final_versio

Numerical study of parametric pumping current in mesoscopic systems in the presence of a magnetic field

We numerically study the parametric pumped current when magnetic field is applied both in the adiabatic and nonadiabatic regimes. In particular, we investigate the nature of pumped current for systems with resonance as well as antiresonance. It is found that, in the adiabatic regime, the pumped current changes sign across the sharp resonance with long lifetime, while the nonadiabatic pumped current at finite frequency does not. When the lifetime of the resonant level is short, the behaviors of the adiabatic and nonadiabatic pumped currents are similar with sign changes. Our results show that, at the energy where complete transmission occurs, the adiabatic pumped current is zero, while the nonadiabatic pumped current is nonzero. Different from the resonant case, both the adiabatic and nonadiabatic pumped currents are zero at antiresonance with complete reflection. We also investigate the pumped current when the other system parameters such as magnetic field, pumped frequency, and pumping potentials are varied. Interesting behaviors are revealed. Finally, we study the symmetry relation of the pumped current for several systems with different spatial symmetries upon reversal of magnetic field. Different from the previous theoretical prediction, we find that a system with general inversion symmetry can pump out a finite current in both the adiabatic and nonadiabatic regimes with an approximate relation I(B)I(-B) at small magnetic field. It has been shown theoretically that for systems with reflection symmetry, the pumped current satisfies the relation I(B)=I(-B) in the adiabatic regime. Our results show that even for systems evolving from the inversion to reflection symmetry, the pumped current still obeys the relation I(B)=I(-B) in the adiabatic regime at small magnetic field. © 2011 American Physical Society.published_or_final_versio

First-principles investigation of transient dynamics of molecular devices

published_or_final_versio

Rephasing Invariants of CP and T Violation in the Four-Neutrino Mixing Models

We calculate the rephasing invariants of CP and T violation in a favorable parametrization of the 4x4 lepton flavor mixing matrix. Their relations with the CP- and T-violating asymmetries in neutrino oscillations are derived, and the matter effects are briefly discussed.Comment: RevTex 9 pages. Slight changes. Phys. Rev. D (in press