541 research outputs found

    On Ecalle's and Brown's polar solutions to the double shuffle equations modulo products

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    Two explicit sets of solutions to the double shuffle equations modulo products were introduced by Ecalle and Brown respectively. We place the two solutions into the same algebraic framework and compare them. We find that they agree up to and including depth four but differ in depth five by an explicit solution to the linearized double shuffle equations with an exotic pole structure

    A novel S-sulfhydrated human serum albumin preparation suppresses melanin synthesis

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    Products of ultraviolet (UV) irradiation such as reactive oxygen species (ROS) and nitric oxide (NO) stimulate melanin synthesis. Reactive sulfur species (RSS) have been shown to have strong ROS and NO scavenging effects. However, the instability and low retention of RSS limit their use as inhibitors of melanin synthesis. The free thiol at Cys34 on human serum albumin (HSA) is highly stable, has a long retention and possess a high reactivity for RSS. We report herein on the developm ent of an HSA based RSS delivery system. Sulfane sulfur derivatives released from sodium polysulfides (Na 2 S n ) react readily with HSA. An assay for estimating the elimination of sulfide from polysulfide showed that almost all of the sulfur released from Na 2 S n bound to HSA. The Na 2 S n -treated HSA was found to efficiently scavenge ROS and NO produced from chemical reagents. The Na 2 S n -treated HSA was also found to inhibit melanin synthesis in B16 melanoma cells and this inhibition was independent of the number of added sulfur atoms. In B16 melanoma cells, the Na 2 S n -treated HSA also inhibited the levels of ROS and NO induced by UV radiation. Finally, the Na 2 S n -treated HSA inhibited melanin synthesis from L-DOPA and mushroom tyrosinase and suppressed the extent of aggregation of melanin pigments. These data suggest that Na 2 S n -treated HSA inhibits tyrosinase activity for melanin synthesis via two pathways; by directly inhibiting ROS signaling and by scavenging NO. These findings indicate that Na 2 S n -treated HSA has potential to be an attractive and effective candidate for use as a skin whitening agent

    The impact of water on slip system activity in olivine and the formation of bimodal crystallographic preferred orientations

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    Crystallographic preferred orientations (CPOs) in olivine are widely used to infer the mechanisms, conditions, and kinematics of deformation of mantle rocks. Recent experiments on water-saturated olivine were the first to produce a complex CPO characterised by bimodal orientation distributions of both [100] and [001] axes and inferred to form by combined activity of (001)[100], (100)[001], and (010)[100] slip. This result potentially provides a new microstructural indicator of deformation in the presence of elevated concentrations of intracrystalline hydrous point defects and has implications for the interpretation of seismic anisotropy. Here, we document a previously unexplained natural example of this CPO type in a xenolith from Lesotho and demonstrate that it too may be explained by elevated concentrations of hydrous point defects. We test and confirm the hypothesis that combined (001)[100], (100)[001], and (010)[100] slip were responsible for formation of this CPO by (1) using high-angular resolution electron backscatter diffraction to precisely characterise the dislocation types present in both the experimental and natural samples and (2) employing visco-plastic self-consistent simulations of CPO evolution to assess the ability of these slip systems to generate the observed CPO. Finally, we utilise calculations based on effective-medium theory to predict the anisotropy of seismic wave velocities arising from the CPO of the xenolith. Maxima in S-wave velocities and anisotropy are parallel to both the shear direction and shear plane normal, whereas maxima in P-wave velocities are oblique to both, adding complexity to interpretation of deformation kinematics from seismic anisotropy.D. Wallis, L.N. Hansen, and A.J. Wilkinson acknowledge support from the Natural Environment Research Council Grant NE/M000966/1. M. Tasaka acknowledges support through a JSPS Research Fellowship for Young Scientists (26-4879) and the Japan Society for the Promotion of Science (16K17832). D.L. Kohlstedt acknowledges support through NASA Grant NNX15AL53G. K.M. Kumamoto acknowledges support through NSF Division of Earth Science grants 1255620 and 1625032

    Search for exotic neutrino-electron interactions using solar neutrinos in XMASS-I

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    We have searched for exotic neutrino-electron interactions that could be produced by a neutrino millicharge, by a neutrino magnetic moment, or by dark photons using solar neutrinos in the XMASS-I liquid xenon detector. We observed no significant signals in 711 days of data. We obtain an upper limit for neutrino millicharge of 5.4×\times10−12e^{-12} e at 90\% confidence level assuming all three species of neutrino have common millicharge. We also set flavor dependent limits assuming the respective neutrino flavor is the only one carrying a millicharge, 7.3×10−12e7.3 \times 10^{-12} e for νe\nu_e, 1.1×10−11e1.1 \times 10^{-11} e for νμ\nu_{\mu}, and 1.1×10−11e1.1 \times 10^{-11} e for ντ\nu_{\tau}. These limits are the most stringent yet obtained from direct measurements. We also obtain an upper limit for the neutrino magnetic moment of 1.8×\times10−10^{-10} Bohr magnetons. In addition, we obtain upper limits for the coupling constant of dark photons in the U(1)B−LU(1)_{B-L} model of 1.3×\times10−6^{-6} if the dark photon mass is 1×10−3\times 10^{-3} MeV/c2/c^{2}, and 8.8×\times10−5^{-5} if it is 10 MeV/c2/c^{2}

    Search for two-neutrino double electron capture on 124^{124}Xe with the XMASS-I detector

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    Double electron capture is a rare nuclear decay process in which two orbital electrons are captured simultaneously in the same nucleus. Measurement of its two-neutrino mode would provide a new reference for the calculation of nuclear matrix elements whereas observation of its neutrinoless mode would demonstrate lepton number violation. A search for two-neutrino double electron capture on 124^{124}Xe is performed using 165.9 days of data collected with the XMASS-I liquid xenon detector. No significant excess above background was observed and we set a lower limit on the half-life as 4.7×10214.7 \times 10^{21} years at 90% confidence level. The obtained limit has ruled out parts of some theoretical expectations. We obtain a lower limit on the 126^{126}Xe two-neutrino double electron capture half-life of 4.3×10214.3 \times 10^{21} years at 90% confidence level as well.Comment: 6 pages, 3 figures, accepted for publication in Physics Letters

    Direct dark matter search by annual modulation in XMASS-I

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    A search for dark matter was conducted by looking for an annual modulation signal due to the Earth's rotation around the Sun using XMASS, a single phase liquid xenon detector. The data used for this analysis was 359.2 live days times 832 kg of exposure accumulated between November 2013 and March 2015. When we assume Weakly Interacting Massive Particle (WIMP) dark matter elastically scattering on the target nuclei, the exclusion upper limit of the WIMP-nucleon cross section 4.3×\times10−41^{-41}cm2^2 at 8 GeV/c2^2 was obtained and we exclude almost all the DAMA/LIBRA allowed region in the 6 to 16 GeV/c2^2 range at ∼\sim10−40^{-40}cm2^2. The result of a simple modulation analysis, without assuming any specific dark matter model but including electron/γ\gamma events, showed a slight negative amplitude. The pp-values obtained with two independent analyses are 0.014 and 0.068 for null hypothesis, respectively. we obtained 90\% C.L. upper bounds that can be used to test various models. This is the first extensive annual modulation search probing this region with an exposure comparable to DAMA/LIBRA.Comment: 5 pages, 4 figure
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