319 research outputs found
Broken S_3 Flavor Symmetry of Leptons and Quarks: Mass Spectra and Flavor Mixing Patterns
We apply the discrete S_3 flavor symmetry to both lepton and quark sectors of
the standard model extended by introducing one Higgs triplet and realizing the
type-II seesaw mechanism for finite neutrino masses. The resultant mass
matrices of charged leptons (M_l), neutrinos (M_nu), up-type quarks (M_u) and
down-type quarks (M_d) have a universal form consisting of two terms: one is
proportional to the identity matrix I and the other is proportional to the
democracy matrix D. We argue that the textures of M_l, M_u and M_d are
dominated by the D term, while that of M_nu is dominated by the I term. This
hypothesis implies a near mass degeneracy of three neutrinos and can naturally
explain why the mass matrices of charged fermions are strongly hierarchical,
why the quark mixing matrix is close to I and why the lepton mixing matrix
contains two large angles. We discuss a rather simple perturbation ansatz to
break the S_3 symmetry and obtain more realistic mass spectra of leptons and
quarks as well as their flavor mixing patterns. We stress that the I term,
which used to be ignored from M_l, M_u and M_d, is actually important because
it can significantly modify the smallest lepton flavor mixing angle theta_13 or
three quark flavor mixing angles.Comment: 13 pages, no figures; discussions about CP violation added,
references updated, to appear in Phys. Lett.
Micro Deep Drawing of C1100 Conical-cylindrical Cups
AbstractMicro deep drawing was prompted by the rapid development of micro electro mechanical systems, electron industries, new energy, and biomedical in recent years because of its mass production, high efficiency, high precision, low cost and no pollution. However, most researches concentrated on micro cylindrical cups, few studies were reported on other shaped parts. Micro deep drawing of micro conical-cylindrical cups was investigated in this study by using a micro blanking-deep drawing multiple operation mould. The specimen material was pure copper C1100 with a thickness of 50μm which was thermally treated in vacuum condition at 723K for 1h. Micro deep drawing experiments were carried out at room temperature on a universal testing machine at a drawing velocity of 0.05mm/s with the lubrication of polyethylene (PE) film. The results showed that micro conical-cylindrical cups with internal conical bottom diameter of only 0.4mm were well formed. The drawing force and limiting drawing ratio (LDR) micro conical-cylindrical cups were also discussed at the end of this paper
Axin downregulates TCF-4 transcription via β-catenin, but not p53, and inhibits the proliferation and invasion of lung cancer cells
<p>Abstract</p> <p>Background</p> <p>We previously reported that overexpression of Axin downregulates T cell factor-4 (TCF-4) transcription. However, the mechanism(s) by which Axin downregulates the transcription and expression of TCF-4 is not clear. It has been reported that β-catenin promotes and p53 inhibits TCF-4 transcription, respectively. The aim of this study was to investigate whether β-catenin and/or p53 is required for Axin-mediated downregulation of TCF-4.</p> <p>Results</p> <p>Axin mutants that lack p53/HIPK2 and/or β-catenin binding domains were expressed in lung cancer cells, BE1 (mutant p53) and A549 (wild type p53). Expression of Axin or AxinΔp53 downregulates β-catenin and TCF-4, and knock-down of β-catenin upregulates TCF-4 in BE1 cells. However, expression of AxinΔβ-ca into BE1 cells did not downregulate TCF-4 expression. These results indicate that Axin downregulates TCF-4 transcription via β-catenin. Although overexpression of wild-type p53 also downregulates TCF-4 in BE1 cells, cotransfection of p53 and AxinΔβ-ca did not downregulate TCF-4 further. These results suggest that Axin does not promote p53-mediated downregulation of TCF-4. Axin, AxinΔp53, and AxinΔβ-ca all downregulated β-catenin and TCF-4 in A549 cells. Knock-down of p53 upregulated β-catenin and TCF-4, but cotransfection of AxinΔβ-ca and p53 siRNA resulted in downregulation of β-catenin and TCF-4. These results indicate that p53 is not required for Axin-mediated downregulation of TCF-4. Knock-down or inhibition of GSK-3β prevented Axin-mediated downregulation of TCF-4. Furthermore, expression of Axin and AxinΔp53, prevented the proliferative and invasive ability of BE1 and A549, expression of AxinΔβ-ca could only prevented the proliferative and invasive ability effectively.</p> <p>Conclusions</p> <p>Axin downregulates TCF-4 transcription via β-catenin and independently of p53. Axin may also inhibits the proliferation and invasion of lung cancer cells via β-catenin and p53.</p
Remote Monitoring for the Operation Status of CNC Machine Tools Based on HTML5
In order to improve the accuracy of remote monitoring of computer numerical control (CNC) machine tools and reduce the difficulty of monitoring; a remote monitoring method for CNC machine tools based on HTML5 is proposed in this paper. The core idea of this method is to record external sensor information and internal working condition information in the same time, and then visualize the information in multiple directions. Monitoring accuracy is improved through the combined use of internal and external information. In response to the difficult problem of traditional method monitoring; the internal working condition information, external sensor information, 3D model and multimedia information of CNC machine tools are jointly visualized. The 3D model synchronous motion is driven by real-time working condition data. Remote low-latency multimedia information transmission is implemented by using cloud live broadcast technology
Storage of multiple single-photon pulses emitted from a quantum dot in a solid-state quantum memory
Quantum repeaters are critical components for distributing entanglement over
long distances in presence of unavoidable optical losses during transmission.
Stimulated by Duan-Lukin-Cirac-Zoller protocol, many improved quantum-repeater
protocols based on quantum memories have been proposed, which commonly focus on
the entanglement-distribution rate. Among these protocols, the elimination of
multi-photons (multi-photon-pairs) and the use of multimode quantum memory are
demonstrated to have the ability to greatly improve the
entanglement-distribution rate. Here, we demonstrate the storage of
deterministic single photons emitted from a quantum dot in a
polarization-maintaining solid-state quantum memory; in addition,
multi-temporal-mode memory with , and narrow single-photon pulses
is also demonstrated. Multi-photons are eliminated, and only one photon at most
is contained in each pulse. Moreover, the solid-state properties of both
sub-systems make this configuration more stable and easier to be scalable. Our
work will be helpful in the construction of efficient quantum repeaters based
on all-solid-state devicesComment: Published version, including supplementary materia
Thorium-doping induced superconductivity up to 56 K in Gd1-xThxFeAsO
Following the discovery of superconductivity in an iron-based arsenide
LaO1-xFxFeAs with a superconducting transition temperature (Tc) of 26 K[1], Tc
was pushed up surprisingly to above 40 K by either applying pressure[2] or
replacing La with Sm[3], Ce[4], Nd[5] and Pr[6]. The maximum Tc has climbed to
55 K, observed in SmO1-xFxFeAs[7, 8] and SmFeAsO1-x[9]. The value of Tc was
found to increase with decreasing lattice parameters in LnFeAsO1-xFx (Ln stands
for the lanthanide elements) at an apparently optimal doping level. However,
the F- doping in GdFeAsO is particularly difficult[10,11] due to the lattice
mismatch between the Gd2O2 layers and Fe2As2 layers. Here we report observation
of superconductivity with Tc as high as 56 K by the Th4+ substitution for Gd3+
in GdFeAsO. The incorporation of relatively large Th4+ ions relaxes the lattice
mismatch, hence induces the high temperature superconductivity.Comment: 4 pages, 3 figure
Characterization of epitaxial GaAs MOS capacitors using atomic layer-deposited TiO2/Al2O3 gate stack: study of Ge auto-doping and p-type Zn doping
Electrical and physical properties of a metal-oxide-semiconductor [MOS] structure using atomic layer-deposited high-k dielectrics (TiO2/Al2O3) and epitaxial GaAs [epi-GaAs] grown on Ge(100) substrates have been investigated. The epi-GaAs, either undoped or Zn-doped, was grown using metal-organic chemical vapor deposition method at 620°C to 650°C. The diffusion of Ge atoms into epi-GaAs resulted in auto-doping, and therefore, an n-MOS behavior was observed for undoped and Zn-doped epi-GaAs with the doping concentration up to approximately 1017 cm-3. This is attributed to the diffusion of a significant amount of Ge atoms from the Ge substrate as confirmed by the simulation using SILVACO software and also from the secondary ion mass spectrometry analyses. The Zn-doped epi-GaAs with a doping concentration of approximately 1018 cm-3 converts the epi-GaAs layer into p-type since the Zn doping is relatively higher than the out-diffused Ge concentration. The capacitance-voltage characteristics show similar frequency dispersion and leakage current for n-type and p-type epi-GaAs layers with very low hysteresis voltage (approximately 10 mV)
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