11,323 research outputs found

    Non-perturbative renormalization of overlap quark bilinears on 2+1-flavor domain wall fermion configurations

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    We present renormalization constants of overlap quark bilinear operators on 2+1-flavor domain wall fermion configurations. This setup is being used by the chiQCD collaboration in calculations of physical quantities such as strangeness in the nucleon and the strange and charm quark masses. The scale independent renormalization constant for the axial vector current is computed using the Ward Identity. The renormalization constants for scalar, pseudoscalar and vector current are calculated in the RI-MOM scheme. Results in the MS-bar scheme are also given. The step scaling function of quark masses in the RI-MOM scheme is computed as well. The analysis uses, in total, six different ensembles of three sea quarks each on two lattices with sizes 24^3x64 and 32^3x64 at spacings a=(1.73 GeV)^{-1} and (2.28 GeV)^{-1}, respectively.Comment: 26 pages, 17 figures. More discussions on O(4) breaking effects, and on the perturbative running and a^2p^2 extrapolation of Zs. A subsection for the calculation of the step scaling function of quark mass is added. References added. Version to appear in PR

    A Multicenter prospective study of poor-grade aneurysmal subarachnoid hemorrhage (AMPAS): observational registry study

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    BACKGROUND: Poor-grade aneurysmal subarachnoid hemorrhage (aSAH) is associated with very high mortality and morbidity. Our limited knowledge on predictors of long-term outcome in poor-grade patients with aSAH definitively managed comes from retrospective and prospective studies of small case series of patients in single center. The purpose of the AMPAS is to determine the long-term outcomes in poor-grade patients with different managements within different time after aSAH, and identify the independent predictors of the outcome that help guide the decision on definitive management. METHODS/DESIGN: The AMPAS study is a prospective, multicenter, observational registry of consecutive hospitalized patients with poor grade aSAH (WFNS grade IV and V). The aim is to enroll at least 226 poor-grade patients in 11 high-volume medical centers (eg, >150 aSAH cases per year) affiliated to different universities in China. This study will describe poor grade patients and aneurysm characteristics, treatment strategies (modality and time of definitive management), hospitalization complications and outcomes evolve over time. The definitive management is ruptured aneurysm treatment. Outcomes at 3, 6, 12 months after the management were measured using the Glasgow Outcome Scale and the Modified Rankin Scale. DISCUSSION: The AMPAS is the first prospective, multicenter, observational registry of poor grade aSAH with any management. This study will contribute to a better understanding of significant predictors of outcome in poor grade patients and help guide future treatment of the worst patients after aSAH. TRIAL REGISTRATION: Chinese Clinical Trial Registry: ChiCTR-TNRC-10001041

    Brain explorer for connectomic analysis

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    Visualization plays a vital role in the analysis of multimodal neuroimaging data. A major challenge in neuroimaging visualization is how to integrate structural, functional, and connectivity data to form a comprehensive visual context for data exploration, quality control, and hypothesis discovery. We develop a new integrated visualization solution for brain imaging data by combining scientific and information visualization techniques within the context of the same anatomical structure. In this paper, new surface texture techniques are developed to map non-spatial attributes onto both 3D brain surfaces and a planar volume map which is generated by the proposed volume rendering technique, spherical volume rendering. Two types of non-spatial information are represented: (1) time series data from resting-state functional MRI measuring brain activation; (2) network properties derived from structural connectivity data for different groups of subjects, which may help guide the detection of differentiation features. Through visual exploration, this integrated solution can help identify brain regions with highly correlated functional activations as well as their activation patterns. Visual detection of differentiation features can also potentially discover image-based phenotypic biomarkers for brain diseases

    New Open Conformation of SMYD3 Implicates Conformational Selection and Allostery

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    SMYD3 plays a key role in cancer cell viability, adhesion, migration and invasion. SMYD3 promotes formation of inducible regulatory T cells and is involved in reducing autoimmunity. However, the nearly “closed” substrate-binding site and poor in vitro H3K4 methyltransferase activity have obscured further understanding of this oncogenically related protein. Here we reveal that SMYD3 can adopt an “open” conformation using molecular dynamics simulation and small-angle X-ray scattering. This ligand-binding-capable open state is related to the crystal structure-like closed state by a striking clamshell-like inter-lobe dynamics. The two states are characterized by many distinct structural and dynamical differences and the conformational transition pathway is mediated by a reversible twisting motion of the C-terminal domain (CTD). The spontaneous transition from the closed to open states suggests two possible, mutually non-exclusive models for SMYD3 functional regulation and the conformational selection mechanism and allostery may regulate the catalytic or ligand binding competence of SMYD3. This study provides an immediate clue to the puzzling role of SMYD3 in epigenetic gene regulation

    Limits on Light Weakly Interacting Massive Particles from the First 102.8 kg ×{\times} day Data of the CDEX-10 Experiment

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    We report the first results of a light weakly interacting massive particles (WIMPs) search from the CDEX-10 experiment with a 10 kg germanium detector array immersed in liquid nitrogen at the China Jinping Underground Laboratory with a physics data size of 102.8 kg day. At an analysis threshold of 160 eVee, improved limits of 8 ×1042\times 10^{-42} and 3 ×1036\times 10^{-36} cm2^{2} at a 90\% confidence level on spin-independent and spin-dependent WIMP-nucleon cross sections, respectively, at a WIMP mass (mχm_{\chi}) of 5 GeV/c2{c}^2 are achieved. The lower reach of mχm_{\chi} is extended to 2 GeV/c2{c}^2.Comment: 5 pages, 4 figure

    Limits on light WIMPs from the CDEX-1 experiment with a p-type point-contact germanium detector at the China Jingping Underground Laboratory

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    We report results of a search for light Dark Matter WIMPs with CDEX-1 experiment at the China Jinping Underground Laboratory, based on 53.9 kg-days of data from a p-type point-contact germanium detector enclosed by a NaI(Tl) crystal scintillator as anti-Compton detector. The event rate and spectrum above the analysis threshold of 475 eVee are consistent with the understood background model. Part of the allowed regions for WIMP-nucleus coherent elastic scattering at WIMP mass of 6-20 GeV are probed and excluded. Independent of interaction channels, this result contradicts the interpretation that the anomalous excesses of the CoGeNT experiment are induced by Dark Matter, since identical detector techniques are used in both experiments.Comment: 5 pages, 5 figure

    A Unified Approach to the Classical Statistical Analysis of Small Signals

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    We give a classical confidence belt construction which unifies the treatment of upper confidence limits for null results and two-sided confidence intervals for non-null results. The unified treatment solves a problem (apparently not previously recognized) that the choice of upper limit or two-sided intervals leads to intervals which are not confidence intervals if the choice is based on the data. We apply the construction to two related problems which have recently been a battle-ground between classical and Bayesian statistics: Poisson processes with background, and Gaussian errors with a bounded physical region. In contrast with the usual classical construction for upper limits, our construction avoids unphysical confidence intervals. In contrast with some popular Bayesian intervals, our intervals eliminate conservatism (frequentist coverage greater than the stated confidence) in the Gaussian case and reduce it to a level dictated by discreteness in the Poisson case. We generalize the method in order to apply it to analysis of experiments searching for neutrino oscillations. We show that this technique both gives correct coverage and is powerful, while other classical techniques that have been used by neutrino oscillation search experiments fail one or both of these criteria.Comment: 40 pages, 15 figures. Changes 15-Dec-99 to agree more closely with published version. A few small changes, plus the two substantive changes we made in proof back in 1998: 1) The definition of "sensitivity" in Sec. V(C). It was inconsistent with our actual definition in Sec. VI. 2) "Note added in proof" at end of the Conclusio

    Search for nucleon decays with EXO-200

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    A search for instability of nucleons bound in 136^{136}Xe nuclei is reported with 223 kg\cdotyr exposure of 136^{136}Xe in the EXO-200 experiment. Lifetime limits of 3.3×1023\times 10^{23} and 1.9×1023\times 10^{23} yrs are established for nucleon decay to 133^{133}Sb and 133^{133}Te, respectively. These are the most stringent to date, exceeding the prior decay limits by a factor of 9 and 7, respectively

    Observation of χc1\chi_{c1} decays into vector meson pairs ϕϕ\phi\phi, ωω\omega\omega, and ωϕ\omega\phi

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    Decays of χc1\chi_{c1} to vector meson pairs ϕϕ\phi\phi, ωω\omega\omega and ωϕ\omega\phi are observed for the first time using (106±4)×106(106\pm4)\times 10^6 \psip events accumulated at the BESIII detector at the BEPCII e+ee^+e^- collider. The branching fractions are measured to be (4.4±0.3±0.5)×104(4.4\pm 0.3\pm 0.5)\times 10^{-4}, (6.0±0.3±0.7)×104(6.0\pm 0.3\pm 0.7)\times 10^{-4}, and (2.2±0.6±0.2)×105(2.2\pm 0.6\pm 0.2)\times 10^{-5}, for χc1ϕϕ\chi_{c1}\to \phi\phi, ωω\omega\omega, and ωϕ\omega\phi, respectively. The observation of χc1\chi_{c1} decays into a pair of vector mesons ϕϕ\phi\phi, ωω\omega\omega and ωϕ\omega\phi indicates that the hadron helicity selection rule is significantly violated in χcJ\chi_{cJ} decays. In addition, the measurement of χcJωϕ\chi_{cJ}\to \omega\phi gives the rate of doubly OZI-suppressed decay. Branching fractions for χc0\chi_{c0} and χc2\chi_{c2} decays into other vector meson pairs are also measured with improved precision.Comment: 4 pages, 2 figure

    Evidence for e+eγχc1,2e^+e^-\to\gamma\chi_{c1, 2} at center-of-mass energies from 4.009 to 4.360 GeV

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    Using data samples collected at center-of-mass energies of s\sqrt{s} = 4.009, 4.230, 4.260, and 4.360 GeV with the BESIII detector operating at the BEPCII collider, we perform a search for the process e+eγχcJe^+e^-\to\gamma\chi_{cJ} (J=0,1,2)(J = 0, 1, 2) and find evidence for e+eγχc1e^+e^-\to\gamma\chi_{c1} and e+eγχc2e^+e^-\to\gamma\chi_{c2} with statistical significances of 3.0σ\sigma and 3.4σ\sigma, respectively. The Born cross sections σB(e+eγχcJ)\sigma^{B}(e^+e^-\to\gamma\chi_{cJ}), as well as their upper limits at the 90% confidence level are determined at each center-of-mass energy.Comment: 8 pages, 7 figures, 3 table
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