3,042 research outputs found

    Identification of Colour Reconnection using Factorial Correlator

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    A new signal is proposed for the colour reconnection in the hadronic decay of W+ W- in e+e- collisions. Using Pythia Monte Carlo it is shown that this signal, being based on the factorial correlator, is more sensitive than the ones using only averaged quantities.Comment: 6 pages 1 postscript figur

    Neutrino Constraints on Inelastic Dark Matter after CDMS II

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    We discuss the neutrino constraints from solar and terrestrial dark matter (DM) annihilations in the inelastic dark matter (iDM) scenario after the recent CDMS II results. To reconcile the DAMA/LIBRA data with constraints from all other direct experiments, the iDM needs to be light (mχ<100m_\chi < 100 GeV) and have a large DM-nucleon cross section (σn∌\sigma_n \sim 10−4^{-4} pb in the spin-independent (SI) scattering and σn∌\sigma_n \sim 10 pb in the spin-dependent (SD) scattering). The dominant contribution to the iDM capture in the Sun is from scattering off Fe/Al in the SI/SD case. Current bounds from Super-Kamiokande exclude the hard DM annihilation channels, such as W+W−W^+W^-, ZZZZ, ttˉt\bar{t} and τ+τ−\tau^+ \tau^-. For soft channels such as bbˉb\bar{b} and ccˉc \bar{c}, the limits are loose, but could be tested or further constrained by future IceCube plus DeepCore. For neutrino constraints from the DM annihilation in the Earth, due to the weaker gravitational effect of the Earth and inelastic capture condition, the constraint exists only for small mass splitting ÎŽ<\delta < 40 keV and mχ∌(10,50)m_\chi \sim (10, 50) GeV even in the τ+τ−\tau^+ \tau^- channel.Comment: 11 pages, 8 figure

    Rapid Evolution of the Mitochondrial Genome in Chalcidoid Wasps (Hymenoptera: Chalcidoidea) Driven by Parasitic Lifestyles

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    Among the Chalcidoids, hymenopteran parasitic wasps that have diversified lifestyles, a partial mitochondrial genome has been reported only from Nasonia. This genome had many unusual features, especially a dramatic reorganization and a high rate of evolution. Comparisons based on more mitochondrial genomic data from the same superfamily were required to reveal weather these unusual features are peculiar to Nasonia or not. In the present study, we sequenced the nearly complete mitochondrial genomes from the species Philotrypesis. pilosa and Philotrypesis sp., both of which were associated with Ficus hispida. The acquired data included all of the protein-coding genes, rRNAs, and most of the tRNAs, and in P. pilosa the control region. High levels of nucleotide divergence separated the two species. A comparison of all available hymenopteran mitochondrial genomes (including a submitted partial genome from Ceratosolen solmsi) revealed that the Chalcidoids had dramatic mitochondrial gene rearrangments, involved not only the tRNAs, but also several protein-coding genes. The AT-rich control region was translocated and inverted in Philotrypesis. The mitochondrial genomes also exhibited rapid rates of evolution involving elevated nonsynonymous mutations

    Quantum Theory Approach for Neutron Single and Double-Slit Diffraction

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    We provide a quantum approach description of neutron single and double-slit diffraction, with specific attention to the cold neutron diffraction (λ≈20\lambda \approx 20\AA) carried out by Zeilinger et al. in 1988. We find the theoretical results are good agreement with experimental data.Comment: 10 page

    Performance of a dipstick dye immunoassay for rapid screening of Schistosoma japonicum infection in areas of low endemicity

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    BACKGROUND: The dipstick dye immunoassay (DDIA), recently commercially available in the People's Republic of China (P.R. China), is a rapid and simple test to detect human antibodies against Schistosoma Japonicum. Its performance and utility for screening schistosome infection in low endemic areas is little known. We therefore carried out a cross-sectional survey in seven villages with low endemicity of schistosomiasis in P.R. China and assessed the performance and utility of DDIA for diagnosis of schistosomiasis. Stool samples were collected and examined by the Kato-Katz method and the miracidium hatching technique. Serum samples, separated from whole blood of participants, were tested by DDIA. RESULTS: 6285 individuals aged 6-65 years old participated in this study, with a prevalence of schistosomiasis of 4.20%. Using stool examination as a gold reference standard, DDIA performed with a high overall sensitivity of 91.29% (95% CI: 87.89-94.69%) and also a high negative predictive value, with a mean value of 99.29% (95% CI: 98.99-99.58%). The specificity of DDIA was only moderate (53.08%, 95% CI: 51.82-54.34%). Multivariate analysis indicated that age, occupation and history of schistosome infection were significantly associated with the false positive results of DDIA. CONCLUSIONS: DDIA is a sensitive, rapid, simple and portable diagnostic assay and can be used as a primary approach for screening schistosome infection in areas of low endemicity. However, more sensitive and specific confirmatory assays need to be developed and combined with DDIA for targeting chemotherapy accurately

    Pseuduscalar Heavy Quarkonium Decays With Both Relativistic and QCD Radiative Corrections

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    We estimate the decay rates of ηc→2Îł\eta_c\rightarrow 2\gamma, ηcâ€Č→2Îł\eta_c'\rightarrow 2\gamma, and J/ψ→e+e−J/\psi\rightarrow e^+ e^-, ψâ€Č→e+e−\psi^\prime\rightarrow e^+e^-, by taking into account both relativistic and QCD radiative corrections. The decay amplitudes are derived in the Bethe-Salpeter formalism. The Bethe-Salpeter equation with a QCD-inspired interquark potential are used to calculate the wave functions and decay widths for these ccˉc\bar{c} states. We find that the relativistic correction to the ratio R≡Γ(ηc→2Îł)/Γ(J/ψ→e+e−)R\equiv \Gamma (\eta_c \rightarrow 2\gamma)/ \Gamma (J/ \psi \rightarrow e^+ e^-) is negative and tends to compensate the positive contribution from the QCD radiative correction. Our estimate gives Γ(ηc→2Îł)=(6−7) keV\Gamma(\eta_c \rightarrow 2\gamma)=(6-7) ~keV and Γ(ηcâ€Č→2Îł)=2 keV\Gamma(\eta_c^\prime \rightarrow 2\gamma)=2 ~keV, which are smaller than their nonrelativistic values. The hadronic widths Γ(ηc→2g)=(17−23) MeV\Gamma(\eta_c \rightarrow 2g)=(17-23) ~MeV and Γ(ηcâ€Č→2g)=(5−7) MeV\Gamma(\eta_c^\prime \rightarrow 2g)=(5-7)~MeV are then indicated accordingly to the first order QCD radiative correction, if αs(mc)=0.26−0.29\alpha_s(m_c)=0.26-0.29. The decay widths for bbˉb\bar b states are also estimated. We show that when making the assmption that the quarks are on their mass shells our expressions for the decay widths will become identical with that in the NRQCD theory to the next to leading order of v2v^2 and αs\alpha_s.Comment: 14 pages LaTex (2 figures included

    Spin Relaxation in Single Layer Graphene with Tunable Mobility

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    Graphene is an attractive material for spintronics due to theoretical predictions of long spin lifetimes arising from low spin-orbit and hyperfine couplings. In experiments, however, spin lifetimes in single layer graphene (SLG) measured via Hanle effects are much shorter than expected theoretically. Thus, the origin of spin relaxation in SLG is a major issue for graphene spintronics. Despite extensive theoretical and experimental work addressing this question, there is still little clarity on the microscopic origin of spin relaxation. By using organic ligand-bound nanoparticles as charge reservoirs to tune mobility between 2700 and 12000 cm2/Vs, we successfully isolate the effect of charged impurity scattering on spin relaxation in SLG. Our results demonstrate that while charged impurities can greatly affect mobility, the spin lifetimes are not affected by charged impurity scattering.Comment: 13 pages, 5 figure

    Strain Rate Distribution in South‐Central Tibet From Two Decades of InSAR and GPS

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    The degree to which deformation and seismicity is focused on major mapped structures remains a key unknown in assessing seismic hazards and testing continental deformation models. Here we combine 208 Global Positioning System (GPS) velocities with 12‐track Interferometric Synthetic Aperture Radar (InSAR) rate maps to form high‐resolution velocity and strain rate fields for south‐central Tibet. Our results show that deformation is not evenly distributed across the region. We find a few zones with high strain rates, most notably the Yutian‐Zhongba strain rate zone. However, the average of the strain rates is similar within and outside the mapped fault zones. In addition, the slip rates are low on all the conjugate strike‐slip faults widespread in central Tibet. The observations are difficult to reconcile with time‐invariant block models or with continuum models that lack mechanisms for strain localization. Our results support arguments that the most robust estimates of seismic hazard should integrate seismicity catalogues, active fault maps, and geodetic strain rate models
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