44,140 research outputs found

    Authentication of Chinese crude drug, Gecko, by allele-specific diagnostic PCR

    Get PDF
    Based on the sequences of the mitochondrial 12S rRNA gene fragment of 17 samples from Gekkonidae, Salamandridae, Agamidae and Hynobiidae, respectively, a pair of allele-specific primers was designed for differentiating the Chinese medicinal material Gecko from its adulterants by PCR. The results of amplification with the primers indicate that amplicons from the templates of Gekko gecko were clearly revealed by agarose gel electrophoresis, whereas no evident amplicons were found from other species. The primers were employed to identify crude drug samples from different sources, Among a total of 9 samples, 3 were diagnosed as genuine Gecko. This result is consistent with morphological identification and DNA sequence analyses

    BB-to-Glueball form factor and Glueball production in BB decays

    Full text link
    We investigate transition form factors of BB meson decays into a scalar glueball in the light-cone formalism. Compared with form factors of BB to ordinary scalar mesons, the BB-to-glueball form factors have the same power in the expansion of 1/mB1/m_B. Taking into account the leading twist light-cone distribution amplitude, we find that they are numerically smaller than those form factors of BB to ordinary scalar mesons. Semileptonic BGlνˉB\to Gl\bar\nu, BGl+lB\to Gl^+l^- and BsGl+lB_s\to Gl^+l^- decays are subsequently investigated. We also analyze the production rates of scalar mesons in semileptonic BB decays in the presence of mixing between scalar qˉq\bar qq and glueball states. The glueball production in BcB_c meson decays is also investigated and the LHCb experiment may discover this channel. The sizable branching fraction in Bc(π+π)lνˉB_c\to (\pi^+\pi^-)l^-\bar\nu, Bc(K+K)lνˉB_c\to (K^+K^-)l^-\bar\nu or Bc(π+ππ+π)lνˉB_c\to (\pi^+\pi^-\pi^+\pi^-)l^-\bar\nu could be a clear signal for a scalar glueball state.Comment: 17 pages, 3 figure, revtex

    Isospin Effect on the Process of Multifragmentation and Dissipation at Intermediate Energy Heavy Ion Collisions

    Get PDF
    In the simulation of intermediate energy heavy ion collisions by using the isospin dependent quantum molecular dynamics, the isospin effect on the process of multifragmentation and dissipation has been studied. It is found that the multiplicity of intermediate mass fragments NimfN_{imf} for the neutron-poor colliding system is always larger than that for the neutron-rich system, while the quadrupole of single particle momentum distribution QzzQ_{zz} for the neutron-poor colliding system is smaller than that of the neutron-rich system for all projectile-target combinations studied at the beam energies from about 50MeV/nucleon to 150MeV/nucleon. Since QzzQ_{zz} depends strongly on isospin dependence of in-medium nucleon-nucleon cross section and weakly on symmetry potential at the above beam energies, it may serve as a good probe to extract the information on the in-medium nucleon-nucleon cross section. The correlation between the multiplicity NimfN_{imf} of intermediate mass fragments and the total numer of charged particles NcN_c has the behavior similar to QzzQ_{zz}, which can be used as a complementary probe to the in-medium nucleon-nucleon cross section.Comment: 18 pages, 9 figure

    Reflection Symmetry and Quantized Hall Resistivity near Quantum Hall Transition

    Full text link
    We present a direct numerical evidence for reflection symmetry of longitudinal resistivity ρxx\rho_{xx} and quantized Hall resistivity ρxy\rho_{xy} near the transition between ν=1\nu=1 quantum Hall state and insulator, in accord with the recent experiments. Our results show that a universal scaling behavior of conductances, σxx\sigma_{xx} and σxy\sigma_{xy}, in the transition regime decide the reflection symmetry of ρxx\rho_{xx} and quantization of ρxy\rho_{xy}, independent of particle-hole symmetry. We also find that in insulating phase away from the transition region ρxy\rho_{xy} deviates from the quantization and diverges with ρxx\rho_{xx}.Comment: 3 pages, 4 figures; figure 4 is replace

    Determination of InN/Diamond Heterojunction Band Offset by X-ray Photoelectron Spectroscopy

    Get PDF
    Diamond is not only a free standing highly transparent window but also a promising carrier confinement layer for InN based devices, yet little is known of the band offsets in InN/diamond system. X-ray photoelectron spectroscopy was used to measure the energy discontinuity in the valence band offset (VBO) of InN/diamond heterostructure. The value of VBO was determined to be 0.39 ± 0.08 eV and a type-I heterojunction with a conduction band offset (CBO) of 4.42 ± 0.08 eV was obtained. The accurate determination of VBO and CBO is important for the application of III-N alloys based electronic devices

    The edge state network model and the global phase diagram

    Full text link
    The effects of randomness are investigated in the fractional quantum Hall systems. Based on the Chern-Simons Ginzburg-Landou theory and considering relevant quasi-particle tunneling, the edge state network model for the hierarchical state is introduced and the plateau-plateau transition and liquid-insulator transition are discussed. This model has duality which corresponds to the relation of the quantum Hall liquid phase and the Hall insulating phase and reveals a mechanism in the weak coupling regime.Comment: 5 page RevTe

    Scalar potential effect in an integrable Kondo model

    Get PDF
    To study the impurity potential effect to the Kondo problem in a Luttinger liquid, we propose an integrable model of two interacting half-chains coupled with a single magnetic impurity ferromagnetically. It is shown that the scalar potential effectively reconciles the spin dynamics at low temperatures. Generally, there is a competition between the Kondo coupling JJ and the impurity potential VV. When the ferromagnetic Kondo coupling dominates over the impurity potential (V<SJV<|SJ|), the Furusaki-Nagaosa many-body singlet can be perfectly realized. However, when the impurity potential dominates over the Kondo coupling (VSJV\geq |SJ|), the fixed point predicted by Furusaki and Nagaosa is unstable and the system must flow to a weak coupling fixed point. It is also found that the effective moment of the impurity measured from the susceptibility is considerably enlarged by the impurity potential. In addition, some quantum phase transitions driven by the impurity potential are found and the anomaly residual entropy is discussed.Comment: volume enlarged, some new references are adde
    corecore