Lorentz transformation in Maxwell equations for slowly moving media

We use the method of field decomposition, a technique widely used in relativistic magnetohydrodynamics, to study the small velocity approximation (SVA) of the Lorentz transformation in Maxwell equations for slowly moving media. The "deformed" Maxwell equations derived under the SVA in the lab frame can be put into the conventional form of Maxwell equations in the medium's comoving frame. Our results show that the Lorentz transformation in the SVA up to $O(v/c)$ ($v$ is the speed of the medium and $c$ is the speed of light in vacuum) is essential to derive these equations: the time and charge density must also change when transforming to a different frame even in the SVA, not just the position and current density as in the Galilean transformation. This marks the essential difference of the Lorentz transformation from the Galilean one. We show that the integral forms of Faraday and Ampere equations for slowly moving surfaces are consistent with Maxwell equations. We also present Faraday equation the covariant integral form in which the electromotive force can be defined as a Lorentz scalar independent of the observer's frame. No evidences exist to support an extension or modification of Maxwell equations.Comment: 16 pages, 1 figure, 3 tables. Section VI is added about integral forms of Faraday and Ampere laws for moving surfaces. Part of Section IV and V are rewitte

Quantum state transmission in a cavity array via two-photon exchange

The dynamical behavior of a coupled cavity array is investigated when each cavity contains a three-level atom. For the uniform and staggered intercavity hopping, the whole system Hamiltonian can be analytically diagonalized in the subspace of single-atom excitation. The quantum state transfer along the cavities is analyzed in detail for distinct regimes of parameters, and some interesting phenomena including binary transmission, selective localization of the excitation population are revealed. We demonstrate that the uniform coupling is more suitable for the quantum state transfer. It is shown that the initial state of polariton located in the first cavity is crucial to the transmission fidelity, and the local entanglement depresses the state transfer probability. Exploiting the metastable state, the distance of the quantum state transfer can be much longer than that of Jaynes-Cummings-Hubbard model. A higher transmission probability and longer distance can be achieved by employing a class of initial encodings and final decodings.Comment: 8 pages, 7 figures. to appear in Phys. Rev.

Online near-infrared analysis coupled with MWPLS and SiPLS models for the multi-ingredient and multi-phase extraction of licorice (Gancao)

Additional file 1. Table S1. The sampling intervals in different extraction phases. Table S2. The HPLC results of different indicators. Table S3. The evaluation parameters of PLS and SiPLS models

Residual Stress Analysis of Laser Remanufacturing

Laser remanufacturing is an advanced repairing method to remanufacture damaged parts based on laser processing, such as laser cladding and laser welding. As a critical factor in determining the remanufacturing quality, residual stress of different laser-remanufactured parts was analysed by numerical methods based on deactivating and reactivating element theory, as well as experimental methods such as X-ray diffraction and hole drilling measurements. The distributions and evolution law of residual stress during multipass laser welding of 7A52 high-strength aluminium alloy, and the effects of forming strategy, heat input and solid-state phase transition on residual stress in the laser cladding forming layers of QT 500 cast iron and FV520B high strength steel, were emphatically studied. The simulation results of residual stress fit well with the experimental results, indicating that both residual stress and its accumulation phenomenon would occur during the laser welding and laser cladding forming, and were affected by factors such as welding pass, heat input and phase transition. It is feasible to control residual stress by using cross path forming strategy, less heat input and alloying power materials with low martensite transition point (Ms)

Characterization of the Antheraea pernyi abnormal wing disc gene that may contribute to its temperature tolerance

It has been known that the abnormal wing disc (awd) gene encodes a nucleoside diphosphate kinase and is closely related to wing development in Drosophila melanogaster and Bombyx mori. In the present study, the awd gene was isolated and characterized from Antheraea pernyi, a well-known wild silkmoth. The isolated cDNA sequence is 666 bp in length with an open reading frame of 462 bp encoding a polypeptide of 153 amino acids, which contains a putative nucleoside diphosphate kinases active site motif and conserved multimer interface. The deduced A. pernyi awd protein sequence reveals 75, 82 and 96% identity with its homologue of Homo sapiens, D. melanogaster, and B. mori, respectively. Semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis showed that the awd gene was transcribed during all four developmental stages (egg, larva, pupa, and moth), and present in all tissues tested (blood, midgut, silk glands, Malpighian tublues, spermaries, ovaries, brain, muscle, fat body and body wall), with the highest abundance in Malpighian tubules. Interestingly, mRNA expression level in pupal fat body was significantly down-regulated after cold shock (4°C) compared with the control (26°C) and significantly up-regulated after heat shock (46°C). The results indicated that the A. pernyi awd gene is inducible, and that its expression effect is different after cold stress and heat stress. Consequently, we refer that the product of the awd gene may contribute to its temperature tolerance.Key words: Antheraea pernyi, abnormal wing disc gene, cloning, expression pattern, temperature stress

High temperature thermodynamics of strongly interacting s-wave and p-wave Fermi gases in a harmonic trap

We theoretically investigate the high-temperature thermodynamics of a strongly interacting trapped Fermi gas near either s-wave or p-wave Feshbach resonances, using a second order quantum virial expansion. The second virial coefficient is calculated based on the energy spectrum of two interacting fermions in a harmonic trap. We consider both isotropic and anisotropic harmonic potentials. For the two-fermion interaction, either s-wave or p-wave, we use a pseudopotential parametrized by a scattering length and an effective range. This turns out to be the simplest way of encoding the energy dependence of the low-energy scattering amplitude or phase shift. This treatment of the pseudopotential can be easily generalized to higher partial-wave interactions. We discuss how the second virial coefficient and thermodynamics are affected by the existence of these finite-range interaction effects. The virial expansion result for a strongly interacting s -wave Fermi gas has already been proved very useful. In the case of p-wave interactions, our results for the high-temperature equation of state are applicable to future high-precision thermodynamic measurements for a spin-polarized Fermi gas near a p-wave Feshbach resonance.Comment: 12 pages,10 figure