524 research outputs found

    Reactivity of a Nickel(II) Bis(amidate) Complex withmeta-Chloroperbenzoic Acid: Formation of a Potent Oxidizing Species

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    Herein, we report the formation of a highly reactive nickel–oxygen species that has been trapped following reaction of a NiII precursor bearing a macrocyclic bis(amidate) ligand with meta-chloroperbenzoic acid (HmCPBA). This compound is only detectable at temperatures below 250 K and is much more reactive toward organic substrates (i.e., C[BOND]H bonds, C[DOUBLE BOND]C bonds, and sulfides) than previously reported well-defined nickel–oxygen species. Remarkably, this species is formed by heterolytic O[BOND]O bond cleavage of a Ni–HmCPBA precursor, which is concluded from experimental and computational data. On the basis of spectroscopy and DFT calculations, this reactive species is proposed to be a NiIII–oxyl compound

    Search for supersymmetry with a dominant R-parity violating LQDbar couplings in e+e- collisions at centre-of-mass energies of 130GeV to 172 GeV

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    A search for pair-production of supersymmetric particles under the assumption that R-parity is violated via a dominant LQDbar coupling has been performed using the data collected by ALEPH at centre-of-mass energies of 130-172 GeV. The observed candidate events in the data are in agreement with the Standard Model expectation. This result is translated into lower limits on the masses of charginos, neutralinos, sleptons, sneutrinos and squarks. For instance, for m_0=500 GeV/c^2 and tan(beta)=sqrt(2) charginos with masses smaller than 81 GeV/c^2 and neutralinos with masses smaller than 29 GeV/c^2 are excluded at the 95% confidence level for any generation structure of the LQDbar coupling.Comment: 32 pages, 30 figure

    Inclusive V0V^0 Production Cross Sections from 920 GeV Fixed Target Proton-Nucleus Collisions

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    Inclusive differential cross sections dσpA/dxFd\sigma_{pA}/dx_F and dσpA/dpt2d\sigma_{pA}/dp_t^2 for the production of \kzeros, \lambdazero, and \antilambda particles are measured at HERA in proton-induced reactions on C, Al, Ti, and W targets. The incident beam energy is 920 GeV, corresponding to s=41.6\sqrt {s} = 41.6 GeV in the proton-nucleon system. The ratios of differential cross sections \rklpa and \rllpa are measured to be 6.2±0.56.2\pm 0.5 and 0.66±0.070.66\pm 0.07, respectively, for \xf 0.06\approx-0.06. No significant dependence upon the target material is observed. Within errors, the slopes of the transverse momentum distributions dσpA/dpt2d\sigma_{pA}/dp_t^2 also show no significant dependence upon the target material. The dependence of the extrapolated total cross sections σpA\sigma_{pA} on the atomic mass AA of the target material is discussed, and the deduced cross sections per nucleon σpN\sigma_{pN} are compared with results obtained at other energies.Comment: 17 pages, 7 figures, 5 table

    Search for the standard model Higgs boson at LEP

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    Cannulated screw and hexapodal fixator reconstruction for compound upper tibial fractures

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    OBJECTIVES: The aim of the treatment of tibial plateau fractures is to obtain a pain-free and fully functional knee with closed reduction, percutaneous cannulated screw fixation and hexapodal external fixator reconstruction for high energy compound upper tibial fractures. METHODS: Patients with comminuted tibial plateau fractures underwent closed reduction, percutaneous fixation with cannulated screws, and reconstruction with hexapodal external fixator. The follow-up period was 24 months. RESULTS: The clinical and radiological results were good or excellent. The average knee flexion was 125°. CONCLUSION: Our results are successful in the initial stage, however, it should be pointed out that during the long term follow-up osteoarthritis may develop leading to worsening of the condition. Level of Evidence IV, Case Series

    KELT-4Ab: An Inflated Hot Jupiter Transiting The Bright (V~10) Component Of A Hierarchical Triple

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    We report the discovery of KELT-4Ab, an inflated, transiting Hot Jupiter orbiting the brightest component of a hierarchical triple stellar system. The host star is an F star with Teff{T}_{{\rm{eff}}} = 6206±756206\pm 75 K, logg\mathrm{log}g = 4.108±0.0144.108\pm 0.014, [Fe/H][{\rm{Fe}}/{\rm{H}}] = 0.1160.069+0.065-{0.116}_{-0.069}^{+0.065}, M{M}_{*} = 1.2010.061+0.067{1.201}_{-0.061}^{+0.067}   M\;{M}_{\odot }, and R{R}_{*} = 1.6030.038+0.039{1.603}_{-0.038}^{+0.039}   R\;{R}_{\odot }. The best-fit linear ephemeris is BJDTDB{\mathrm{BJD}}_{\mathrm{TDB}}   =  2456193.29157±0.00021\;=\;2456193.29157\pm 0.00021 +E(2.9895936±0.0000048)\quad +\quad E(2.9895936\pm 0.0000048). With a magnitude of V ~ 10, a planetary radius of 1.6990.045+0.046{1.699}_{-0.045}^{+0.046}   RJ\;{R}_{{\rm{J}}}, and a mass of 0.9020.059+0.060{0.902}_{-0.059}^{+0.060}   MJ\;{M}_{{\rm{J}}}, it is the brightest host among the population of inflated Hot Jupiters (RP \u3e 1.5RJ), making it a valuable discovery for probing the nature of inflated planets. In addition, its existence within a hierarchical triple and its proximity to Earth (210 pc) provide a unique opportunity for dynamical studies with continued monitoring with high resolution imaging and precision radial velocities. The projected separation between KELT-4A and KELT-4BC is 328 ± 16 AU and the projected separation between KELT-4B and KELT-4C is 10.30 ± 0.74 AU. Assuming face-on, circular orbits, their respective periods would be 3780 ± 290 and 29.4 ± 3.6 years and the astrometric motions relative to the epoch in this work of both the binary stars around each other and of the binary around the primary star would be detectable now and may provide meaningful constraints on the dynamics of the system

    Clinical performance of an analytically validated assay in comparison to microarray technology to assess PITX2 DNA-methylation in breast cancer

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    Significant evidence has accumulated that DNA-methylation of the paired-like homeodomain transcription factor 2 (PITX2) gene can serve as a prognostic and predictive biomarker in breast cancer. PITX2 DNA-methylation data have been obtained so far from microarray and polymerase chain reaction (PCR)-based research tests. The availability of an analytically validated in vitro methylation-specific real-time PCR assay format (therascreen PITX2 RGQ PCR assay) intended for the determination of the percent methylation ratio (PMR) in the (PITX2) promoter 2 prompted us to investigate whether the clinical performance of these different assay systems generate comparable clinical outcome data. Mathematically converted microarray data of a previous breast cancer study (n = 204) into PMR values leads to a PITX2 cut-off value at PMR 14.73. Recalculation of the data to experimentally equivalent PMRs with the PCR PITX2 assay leads to a cut-off value at PMR 12 with the highest statistical significance. This cut-off predicts outcome of high-risk breast cancer patients to adjuvant anthracycline-based chemotherapy (n = 204; Hazard Ratio 2.48; p < 0.001) comparable to microarray generated results (n = 204; Hazard ratio 2.32; p < 0.0001). The therascreen PITX2 RGQ PCR assay is an analytically validated test with high reliability and robustness and predicts outcome of high-risk breast cancer patients to anthracycline-based chemotherapy
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