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    31509 research outputs found

    SH2B1 beta (SH2-B beta) enhances expression of a subset of nerve growth factor-regulated genes important for neuronal differentiation including genes encoding urokinase plasminogen activator receptor and matrix metalloproteinase 3/10

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    [[abstract]]Previous work showed that the adapter protein SH2B adapter protein beta (SH2B1) (SH2-B) binds to the activated form of the nerve growth factor (NGF) receptor TrkA and is critical for both NGF-dependent neurite outgrowth and maintenance. To identify SH2B beta-regulated genes critical for neurite outgrowth, we performed microarray analysis of control PC12 cells and PC12 cells stably overexpressing SH2B beta (PC12-SH2B beta) or the dominant-negative SH2B beta(R555E) [PC12-SH2B beta(R555E)]. NGF-induced microarray expression of Plaur and Mmp10 genes was greatly enhanced in PC12-SH2B beta cells, whereas NGF-induced Plaur and Mmp3 expression was substantially depressed in PC12-SH2B beta(R555E) cells. Plaur, Mmp3, and Mmp10 are among the 12 genes most highly upregulated after 6 h of NGF. Their protein products [urokinase plasminogen activator receptor (uPAR), matrix metalloproteinase 3 (MMP3), and MMP10] lie in the same pathway of extracellular matrix degradation; uPAR has been shown previously to be critical for NGF-induced neurite outgrowth. Quantitative real-time PCR analysis revealed SH2B beta enhancement of NGF induction of all three genes and the suppression of NGF induction of all three when endogenous SH2Bwas reduced using short hairpin RNA against SH2Band in PC12-SH2B beta(R555E) cells. NGF-induced levels of uPAR and MMP3/10 and neurite outgrowth through Matrigel (MMP3-dependent) were also increased in PC12-SH2B beta cells. These results suggest that SH2B beta stimulates NGF-induced neuronal differentiation at least in part by enhancing expression of a specific subset of NGF-sensitive genes, including Plaur, Mmp3, and/or Mmp10, required for neurite outgrowth.[[fileno]]2050132010009[[department]]生科

    Zero-bias conductance peak in tunneling spectroscopy of hybrid superconductor junctions

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    [[abstract]]A generalized method of image, incorporated with the nonequilibrium Keldysh-Green’s function formalism, is employed to investigate the tunneling spectroscopy of hybrid systems in the configuration of planar junction. In particular, tunneling spectroscopies of several hybrid systems that exhibit zero-bias conductance peaks (ZBCP’s) are examined. The well-known metal–d-wave superconductor (ND) junction is examined in detail. Both the evolution of the ZBCP versus doping and the splitting of the ZBCP in magnetic fields are computed in the framework of the slave-boson mean field theory. Further extension of our method to analyze other states shows that states with particle-hole pairing, such as d-density wave and graphene sheet, are all equivalent to a simple one-dimensional model, which at the same time also describes the polyacetylene. We provide the criteria for the emergence of ZBCP. In particular, broken reflection symmetry at the microscopic level is shown to be a necessary condition for ZBCP to occur.[[fileno]]2010108010005[[department]]物理

    Induced decoherence and entanglement by interacting quantum spin baths

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    [[abstract]]The reduced dynamics of a single qubit or two qubits coupled to an interacting quantum spin bath modeled by an XXZ spin chain is investigated. By using the method of a time-dependent density matrix renormalization group (t-DMRG), we go beyond the uniform coupling central spin model and nonperturbatively evaluate the induced decoherence and entanglement. It is shown that both the decoherence and the entanglement strongly depend on the phase of the underlying spin bath. We show that in general, spin baths can induce entanglement for an initially disentangled pair of qubits. Furthermore, when the spin bath is in the ferromagnetic phase because the qubits directly couple to the order parameter, the reduced dynamics shows an oscillatory type behavior. On the other hand, only for the paramagnetic and the antiferromagnetic phases do the initially entangled states suffer from an entanglement sudden death. By calculating the concurrence, the finite disentanglement time is mapped out for all of the phases in the phase diagram of the spin bath.[[fileno]]2010108010033[[department]]物理

    Proposal for Detecting Top Spin Correlation Effects at the Fermilab Tevatron

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    [[abstract]]We propose to observe the top spin correlation effect at the Fermilab Tevatron through the measurement of the correlated asymmetries of the charged lepton momenta using the dilepton decay events of top and antitop quark pairs. The possibility of reconstructing the events and observing the asymmetries at 3σ level with projected luminosity of the Fermilab Tevatron for run II is demonstrated by simulation. The effect can provide the first direct measurement of the spin of a quark.[[fileno]]2010115010038[[department]]物理

    Interpretation of the neutron scattering data on flux lattices of superconductors

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    [[abstract]]Small angle neutron scattering (SANS) experiments are analyzed using a recently developed and properly generalized one-field effective free energy method. In the case of experiment of Keimer et al. (1994) on YBa2Cu3O7 we show that the fourfold symmetry of the underlying crystal is explicitly broken, but the reflection with respect to the [110] and [11¯0] axes remains a symmetry. The vortex lattice also becomes generally oblique instead of rectangular body centered. An unexpectedly rich phase diagram is described[[fileno]]2010108010025[[department]]物理

    Magnetic and crystallographic properties of the permanent magnet systems (R1-xScx)2Fe14B (R=Y, Nd, Dy, Er, Lu)

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    [[abstract]]Magnetic and crystallographic measurements have been made on the rare-earth iron boride systems (R1-xScx)2Fe14B (R=Y, Nd, Dy, Er, Lu). Powder X-ray diffraction data indicate that a Nd2Fe14B-type single phase persists up to x=0.2 with lattice parameters decreasing slightly due to the smaller metallic radius of the Sc3+ ions. The variation of magnetic moments per formula unit with nonmagnetic Sc substitution depends on the smaller Sc size and the nature of the magnetic alignment of the rare-earth sublattice (nonmagnetic in Y and Lu, ferromagnetic axial in Nd, ferromagnetic planar in Er, and antiferromagnetic axial in Dy) with respect to the iron sublattice. The Curie temperature TC decreases monotonically with progressive addition of Sc atoms[[fileno]]2010102010037[[department]]物理

    Identification of 88Se and new levels in 84,86Se

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    [[abstract]]From the analysis of γ-γ-γ coincidence data taken with Gammasphere of the prompt γ rays in the spontaneous fission of 252Cf, the 2+→0+ transition in 88Se was identified for the first time. Also, the 4+→2+ and 6+→4+ transitions in 86Se were identified along with four new states above 4+ in 84Se. Surprisingly, the 2+ energy rises in 88Se compared to 86Se. This increase in energy could arise from the interaction of a low-lying excited 0+ state with different deformation and the 0+ ground state to depress the ground-state energy.[[fileno]]2010125010058[[department]]物理

    Identification of high spin states in 100Zr

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    [[abstract]]Eight new high spin states and 23 new γ transitions have been identified in 100Zr from studies of 252Cf spontaneous fission with Gammasphere. A near-spherical excited band in 100Zr based on the 331.1 keV 0+ state is extended from 4+ up to 12+. A ΔI=1 band with band-head energy of 2316.1 keV is extended.[[fileno]]2010125010057[[department]]物理

    Ternary fission of 252Cf: 3368 keV γ radiation from 10Be fragments

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    [[abstract]]Ternary fission of 252Cf was studied at Gammasphere with eight ΔE×E particle telescopes. After Doppler correction, the 3368 keV 2+→0+ transition in 10Be was found in coincidence with the 10Be fragments with no evidence for any γ rays not Doppler shifted for 10Be with >21 MeV kinetic energy. The ratio of the first 2+ to ground-state population probabilities was estimated as N(2+)∕N(0+)=0.160±0.025. The angular distribution for 3368 keV γ rays indicated the spin alignment of excited 10Be nuclei preferentially is parallel or antiparallel to their momentum.[[fileno]]2010125010046[[department]]物理

    Pulsed electron beam annealing of phosphorus-implanted CuInS2

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    [[abstract]]Pulsed electron beam annealing of phosphorus-implanted CuInS2 has been found to be an efficient method in p-type doping of CuInS2. A sheet resistance as low as 10.1 π/□, a sheet carrier concentration as high as 2.6×1016 cm−2, and a hole mobility as high as 499 cm2/V s have been obtained. The irradiation energy density for the best doping condition was determined to be in the range ~11–13 J/cm2. Using Van der Pauw/Hall technique in conjunction with a chemical etching technique, effective carrier concentration profiles have been determined with a maximum carrier concentration of 9×1019 cm−3. Excellent p-n CuInS2 homojunctions have been fabricated by electron beam pulse annealing with an ideality factor of 1.75.[[fileno]]2010122010037[[department]]物理


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