13,432 research outputs found

    Top-bottom mass hierarchy, sμs-\mu puzzle and gauge coupling unification with split multiplets

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    A supersymmetric 5D SU(5) grand unification is considered. The SU(5) is broken down to GSM=SU(3)×SU(2)×U(1)G_{SM}=SU(3)\times SU(2)\times U(1) by the Z2×Z2Z_2\times Z_2' assignment of the bulk field(s). The matter fields are located at the fixed point(s). In the bulk, a Higgs multiplet 5ˉH\bar 5_H(containing the bottom doublet H1H_1) and the SU(5) gauge multiplet are located. At one fixed point, H2H_2(the top doublet) and the standard model matter multiplets are presented. Because of the difference of the locations of H1H_1 and H2H_2, one can obtain a hierarchy between top and bottom Yukawa couplings. We also present a possibility to understand the sμs-\mu mass puzzle in this framework of the split multiplet.Comment: LaTeX file of 17 pages including 3 eps figures. A note is added and typo errors corrected. To appear in Euro. Phys. J.

    Antiferromagnetic and structural transitions in the superoxide KO2 from first principles: A 2p-electron system with spin-orbital-lattice coupling

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    KO2 exhibits concomitant antiferromagnetic (AFM) and structural transitions, both of which originate from the open-shell 2p electrons of O2_{2}^{-} molecules. The structural transition is accompanied by the coherent tilting of O2_{2}^{-} molecular axes. The interplay among the spin-orbital-lattice degrees of freedom in KO2 is investigated by employing the first-principles electronic structure theory and the kinetic-exchange interaction scheme. We have shown that the insulating nature of the high symmetry phase of KO2 at high temperature (T) arises from the combined effect of the spin-orbit coupling and the strong Coulomb correlation of O 2p electrons. In contrast, for the low symmetry phase of KO2 at low T with the tilted O2_{2}^{-} molecular axes, the band gap and the orbital ordering are driven by the combined effects of the crystal-field and the strong Coulomb correlation. We have verified that the emergence of the O 2p ferro-orbital ordering is essential to achieve the observed AFM structure for KO2

    Modulation of A375 human melanoma cell proliferation and apoptosis by nitric oxide

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    The present study aimed to assess the effect of NO• on melanoma A375 cell growth and apoptotic cell death. Trypan blue exclusion assay was employed to detect the cytotoxicity induced by controlled steady-state concentrations (given in µM • min) of NO•. The characteristics of the cellular cell cycle and apoptosis in NO•-treated A375 cells were also analyzed by Annexin V/PI and DNA fragmentation assays. Western blotting was applied to detect the expression of apoptosis-related proteins (p53, Bax, Fas, DR5, caspase-3 and -9, and PARP). When exposed to preformed 100% NO• for 8 h reactor system, a cumulative dose of 3360 μM • min reduced the viability by 22% 24 h after treatment and promoted apoptosis, 2.9- and 12.2-folds 24 and 48 h after treatment higher than the argon control, respectively. Cell cycle analysis 48 h after treatment revealed S-phase arrest in cells treated with 3360 μM • min NO•. It was also observed that the expression of p53, DR5, caspase 9 and PARP increased significantly upon NO• treatment. In addition, the present study assessed the inhibitory effects of endogenous NO• on the proliferation of human melanoma cells by employing specific (AMG, 1400W and/or SMTC) and nonspecific (NMA) NO• synthase (NOS) inhibitors resulting in melanoma cell growth inhibition; the highest cytotoxic effect was seen when inducible NOS inhibition by 1 mM 1400W treatment. Collectively, the present data suggest that NO• is involved in a key mechanism limiting melanoma proliferation and apoptosis, which may play in improving the efficacy of melanoma treatment

    Online home appliance control using EEG-Based brain-computer interfaces

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    Brain???computer interfaces (BCIs) allow patients with paralysis to control external devices by mental commands. Recent advances in home automation and the Internet of things may extend the horizon of BCI applications into daily living environments at home. In this study, we developed an online BCI based on scalp electroencephalography (EEG) to control home appliances. The BCI users controlled TV channels, a digital door-lock system, and an electric light system in an unshielded environment. The BCI was designed to harness P300 andN200 components of event-related potentials (ERPs). On average, the BCI users could control TV channels with an accuracy of 83.0% ?? 17.9%, the digital door-lock with 78.7% ?? 16.2% accuracy, and the light with 80.0% ?? 15.6% accuracy, respectively. Our study demonstrates a feasibility to control multiple home appliances using EEG-based BCIs
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