Analysis of Ωc∗(css)\Omega_c^*(css) and Ωb∗(bss)\Omega_b^*(bss) with QCD sum rules

In this article, we calculate the masses and residues of the heavy baryons $\Omega_c^*(css)$ and $\Omega_b^*(bss)$ with spin-parity ${3/2}^+$ with the QCD sum rules. The numerical values are compatible with experimental data and other theoretical estimations.Comment: 13 pages, 8 figures, slight versio

Conductance fluctuations in a quantum dot under almost periodic ac pumping

It is shown that the variance of the linear dc conductance fluctuations in an open quantum dot under a high-frequency ac pumping depends significantly on the spectral content of the ac field. For a sufficiently strong ac field $\gamma\tau_{\phi}<< 1$, where $1/\tau_{\phi}$ is the dephasing rate induced by ac noise and $\gamma$ is the electron escape rate, the dc conductance fluctuations are much stronger for the harmonic pumping than in the case of the noise ac field of the same intensity. The reduction factor $r$ in a static magnetic field takes the universal value of 2 only for the white--noise pumping. For the strictly harmonic pumping $A(t)=A_{0}\cos\omega t$ of sufficiently large intensity the variance is almost insensitive to the static magnetic field $r-1= 2\sqrt{\tau_{\phi}\gamma} << 1$. For the quasi-periodic ac field of the form $A(t)=A_{0} [\cos(\omega_{1} t)+\cos(\omega_{2} t)]$ with $\omega_{1,2} >> \gamma$ and $\gamma\tau_{\phi} << 1$ we predict the novel effect of enchancement of conductance fluctuations at commensurate frequencies $\omega_{2}/\omega_{1}=P/Q$.Comment: 4 pages RevTex, 4 eps figures; the final version to appear in Phys.Rev.

Melting behavior of ultrathin titanium nanowires

The thermal stability and melting behavior of ultrathin titanium nanowires with multi-shell cylindrical structures are studied using molecular dynamic simulation. The melting temperatures of titanium nanowires show remarkable dependence on wire sizes and structures. For the nanowire thinner than 1.2 nm, there is no clear characteristic of first-order phase transition during the melting, implying a coexistence of solid and liquid phases due to finite size effect. An interesting structural transformation from helical multi-shell cylindrical to bulk-like rectangular is observed in the melting process of a thicker hexagonal nanowire with 1.7 nm diameter.Comment: 4 pages, 4 figure

Magic structures of helical multi-shell zirconium nanowires

The structures of free-standing zirconium nanowires with 0.6$-$2.8 nm in diameter are systematically studied by using genetic algorithm simulations with a tight-binding many body potential. Several multi-shell growth sequences with cylindrical structures are obtained. These multi-shell structures are composed of coaxial atomic shells with the three- and four-strands helical, centered pentagonal and hexagonal, and parallel double-chain-core curved surface epitaxy. Under the same growth sequence, the numbers of atomic strands in inner- and outer-shell show even-odd coupling and usually differ by five. The size and structure dependence of angular correlation functions and vibrational properties of zirconium nanowire are also discussed.Comment: 14 pages, 4 figure

Higher bundle gerbes and cohomology classes in gauge theories

The notion of a higher bundle gerbe is introduced to give a geometric realization of the higher degree integral cohomology of certain manifolds. We consider examples using the infinite dimensional spaces arising in gauge theories.Comment: 16 pages, LaTe

Numerical study on regular wave overtopping flows over sea dike

Based on the filtered Navier-Stokes equations and Smagorinsky turbulence model, a numerical wave flume is developed to investigate regular wave overtopping flow over trapezoidal smooth impermeable sea dike. Simulation of wave breaking is carried out to validate the numerical wave flume with wave generation and absorbing modules. With the in-house developed code, a series of test cases combined different crest heights and wave parameters are carried out. These results are compared with experimental results and numerical results available. The varying tendency of layer thickness and maximum velocity along dike crest is analyzed for both non-breaking and breaking regular waves. Then, the relationship between the magnitude of overtopping flow velocity and overtopping discharge is investigated

Domain Wall Resistance in Perpendicular (Ga,Mn)As: dependence on pinning

We have investigated the domain wall resistance for two types of domain walls in a (Ga,Mn)As Hall bar with perpendicular magnetization. A sizeable positive intrinsic DWR is inferred for domain walls that are pinned at an etching step, which is quite consistent with earlier observations. However, much lower intrinsic domain wall resistance is obtained when domain walls are formed by pinning lines in unetched material. This indicates that the spin transport across a domain wall is strongly influenced by the nature of the pinning.Comment: 9 pages, 3 figure

Conductance Fluctuations of Open Quantum Dots under Microwave Radiation

We develop a time dependent random matrix theory describing the influence of a time-dependent perturbation on mesoscopic conductance fluctuations in open quantum dots. The effect of external field is taken into account to all orders of perturbation theory, and our results are applicable to both weak and strong fields. We obtain temperature and magnetic field dependences of conductance fluctuations. The amplitude of conductance fluctuations is determined by electron temperature in the leads rather than by the width of electron distribution function in the dot. The asymmetry of conductance with respect to inversion of applied magnetic field is the main feature allowing to distinguish the effect of direct suppression of quantum interference from the simple heating if the frequency of external radiation is larger than the temperature of the leads $\hbar\omega \gg T$.Comment: 7 pages, 5 figure

Effects of chitosan addition on growth performance, diarrhoea, anti-oxidative function and serum immune parameters of weaned piglets

The present experiment was designed to determine the efficacy of a commercial source of chitosan (CS) to enhance performance, anti-oxidative function, and immune response in weaned pigs. A total of 60 crossbreed piglets (Duroc × Landrace × Yorkshire), with average live bodyweight of 8.85 ± 1.52 kg, were weaned at 28 ± 2 days and randomly assigned to five treatment groups, which were fed maize-soybean meal diets containing 0 (basal diet, control) and 250, 500, 1000, and 2000 mg/kg CS. The experiment lasted for two weeks. Body weight was recorded and daily feed intake was calculated. Faecal consistency was monitored for the overall period. After two weeks, blood samples were collected and anti-oxidative and immune parameters were determined. The results showed that CS improved average daily gain and daily gain: daily feed intake during the experiment. Mean faecal score values for the second week were improved by CS, which showed decreased values compared with the control diet. The CS increased the total antioxidant capacity and the activities of superoxide dismutase, catalase and glutathione peroxidase and the content of reduced glutathione in serum, and decreased the malondialdehyde and cortisol contents of serum. Furthermore, CS increased the levels of serum IL-1β，IL-2 and IgG. These findings suggested that the use of CS improved performance and anti-oxidative function, and regulated the immune response of weaned pigs.Keywords: Anti-oxidative capability, chitosan, immunity, performance, piglet

Analysis of Ωb−(bss)\Omega_b^-(bss) and Ωc0(css)\Omega_c^0(css) with QCD sum rules

In this article, we calculate the masses and the pole residues of the ${1/2}^+$ heavy baryons $\Omega_c^0(css)$ and $\Omega_b^-(bss)$ with the QCD sum rules. The numerical values $M_{\Omega_c^0}=(2.72\pm0.18) \rm{GeV}$ (or $M_{\Omega_c^0}=(2.71\pm0.18) \rm{GeV}$) and $M_{\Omega_b^-}=(6.13\pm0.12) \rm{GeV}$ (or $M_{\Omega_b^-}=(6.18\pm0.13) \rm{GeV}$) are in good agreement with the experimental data.Comment: 18 pages, 18 figures, slight revisio