142 research outputs found

    Multiple sources of infection and potential endemic characteristics of the large outbreak of dengue in Guangdong in 2014

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    A large outbreak of dengue, with the most documented cases, occurred in Guangdong China in 2014. Epidemiological studies and phylogenetic analysis of the isolated dengue virus (DENV) showed this outbreak was attributed to multiple sources and caused by at least two genotypes of DENV-1 (Genotypes I and III) and two genotypes of DENV-2 (Cosmopolitan and Asian I Genotypes). A retrospective review and phylogenetic analysis of DENV isolated in Guangdong showed that DENV-1 Genotype I strains were reported continuously during 2004-2014, Genotype III strains were reported during 2009-2014 ; DENV-2 Cosmopolitan and Asian I Genotype strains were reported continuously during 2012-2014. At least 45,171 cases were reported in this outbreak, with 65.9% of the patients in the 21-55-year-old group. A trend toward a decrease in the daily newly emerged cases lagged by approximately 20 days compared with the mosquito density curve. Several epidemiological characteristics of this outbreak and the stably sustained serotypes and genotypes of DENV isolated in Guangdong suggest that Guangdong has been facing a threat of transforming from a dengue epidemic area to an endemic area. The high temperature, drenching rain, rapid urbanization, and pandemic of dengue in Southeast Asia may have contributed to this large outbreak of dengue

    Effects of Exogenous Cellulase Source on In Vitro Fermentation Characteristics and Methane Production of Crop Straws and Grasses

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    In vitro fermentation experiments were conducted to investigate the effects of 3 sources of exogenous cellulase products (EC) at 4 dose rates (DR) (0, 12, 37 and 62 IU/g of DM) on degradation of forage and methane production by mixed rumen micro-organisms of goats. The maximum gas production (Vf) of grasses was higher (P<0.001) in Neocallimastix patriciarum (NP) group than those in Trichoderma reesei (TR) and Trichoderma longibrachiatum (TL) groups. Quadratic increases in dry matter degradation (DMD) of forage and neutral detergent fiber (NDFD) of straw were observed for all EC, with optimum DR in the low range. Supplementation of EC originated from TR and NP increased (P<0.001) DMD of forage compared to that from TL. Addition of EC originated from TR and NP also decreased pH value, ammonia nitrogen (NH3-N) and methane (CH4) production compared to that from TL. Quadratic decreases in pH value, NH3-N and CH4 of forage were noted for EC of TR and NP, and with optimum DR in the low range. For short chain fatty acid, the EC of NP increased total volatile fatty acid (TVFA) and acetate concentration and the ratio of acetate to propionate of forage compared with EC of TL and TR, and with optimum DR in the low to medium range. It was concluded that the source of EC differed in fiber degradation and methane emission, and with optimum DR of TR in the low range (from 12 to 37 U/g DM) in improving fiber degradation and decreasing methane emission

    Measurements of the Mass and Full-Width of the ηc\eta_c Meson

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    In a sample of 58 million J/ψJ/\psi events collected with the BES II detector, the process J/ψγηc\psi\to\gamma\eta_c is observed in five different decay channels: γK+Kπ+π\gamma K^+K^-\pi^+\pi^-, γπ+ππ+π\gamma\pi^+\pi^-\pi^+\pi^-, γK±KS0π\gamma K^\pm K^0_S \pi^\mp (with KS0π+πK^0_S\to\pi^+\pi^-), γϕϕ\gamma \phi\phi (with ϕK+K\phi\to K^+K^-) and γppˉ\gamma p\bar{p}. From a combined fit of all five channels, we determine the mass and full-width of ηc\eta_c to be mηc=2977.5±1.0(stat.)±1.2(syst.)m_{\eta_c}=2977.5\pm1.0 ({stat.})\pm1.2 ({syst.}) MeV/c2c^2 and Γηc=17.0±3.7(stat.)±7.4(syst.)\Gamma_{\eta_c} = 17.0\pm3.7 ({stat.})\pm7.4 ({syst.}) MeV/c2c^2.Comment: 9 pages, 2 figures and 4 table. Submitted to Phys. Lett.

    Direct Measurements of the Branching Fractions for D0Ke+νeD^0 \to K^-e^+\nu_e and D0πe+νeD^0 \to \pi^-e^+\nu_e and Determinations of the Form Factors f+K(0)f_{+}^{K}(0) and f+π(0)f^{\pi}_{+}(0)

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    The absolute branching fractions for the decays D0Ke+νeD^0 \to K^-e ^+\nu_e and D0πe+νeD^0 \to \pi^-e^+\nu_e are determined using 7584±198±3417584\pm 198 \pm 341 singly tagged Dˉ0\bar D^0 sample from the data collected around 3.773 GeV with the BES-II detector at the BEPC. In the system recoiling against the singly tagged Dˉ0\bar D^0 meson, 104.0±10.9104.0\pm 10.9 events for D0Ke+νeD^0 \to K^-e ^+\nu_e and 9.0±3.69.0 \pm 3.6 events for D0πe+νeD^0 \to \pi^-e^+\nu_e decays are observed. Those yield the absolute branching fractions to be BF(D0Ke+νe)=(3.82±0.40±0.27)BF(D^0 \to K^-e^+\nu_e)=(3.82 \pm 0.40\pm 0.27)% and BF(D0πe+νe)=(0.33±0.13±0.03)BF(D^0 \to \pi^-e^+\nu_e)=(0.33 \pm 0.13\pm 0.03)%. The vector form factors are determined to be f+K(0)=0.78±0.04±0.03|f^K_+(0)| = 0.78 \pm 0.04 \pm 0.03 and f+π(0)=0.73±0.14±0.06|f^{\pi}_+(0)| = 0.73 \pm 0.14 \pm 0.06. The ratio of the two form factors is measured to be f+π(0)/f+K(0)=0.93±0.19±0.07|f^{\pi}_+(0)/f^K_+(0)|= 0.93 \pm 0.19 \pm 0.07.Comment: 6 pages, 5 figure

    Measurements of J/psi Decays into 2(pi+pi-)eta and 3(pi+pi-)eta

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    Based on a sample of 5.8X 10^7 J/psi events taken with the BESII detector, the branching fractions of J/psi--> 2(pi+pi-)eta and J/psi-->3(pi+pi-)eta are measured for the first time to be (2.26+-0.08+-0.27)X10^{-3} and (7.24+-0.96+-1.11)X10^{-4}, respectively.Comment: 11 pages, 6 figure

    BESII Detector Simulation

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    A Monte Carlo program based on Geant3 has been developed for BESII detector simulation. The organization of the program is outlined, and the digitization procedure for simulating the response of various sub-detectors is described. Comparisons with data show that the performance of the program is generally satisfactory.Comment: 17 pages, 14 figures, uses elsart.cls, to be submitted to NIM

    Measurement of branching fractions for the inclusive Cabibbo-favored ~K*0(892) and Cabibbo-suppressed K*0(892) decays of neutral and charged D mesons

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    The branching fractions for the inclusive Cabibbo-favored ~K*0 and Cabibbo-suppressed K*0 decays of D mesons are measured based on a data sample of 33 pb-1 collected at and around the center-of-mass energy of 3.773 GeV with the BES-II detector at the BEPC collider. The branching fractions for the decays D+(0) -> ~K*0(892)X and D0 -> K*0(892)X are determined to be BF(D0 -> \~K*0X) = (8.7 +/- 4.0 +/- 1.2)%, BF(D+ -> ~K*0X) = (23.2 +/- 4.5 +/- 3.0)% and BF(D0 -> K*0X) = (2.8 +/- 1.2 +/- 0.4)%. An upper limit on the branching fraction at 90% C.L. for the decay D+ -> K*0(892)X is set to be BF(D+ -> K*0X) < 6.6%

    A Measurement of Psi(2S) Resonance Parameters

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    Cross sections for e+e- to hadons, pi+pi- J/Psi, and mu+mu- have been measured in the vicinity of the Psi(2S) resonance using the BESII detector operated at the BEPC. The Psi(2S) total width; partial widths to hadrons, pi+pi- J/Psi, muons; and corresponding branching fractions have been determined to be Gamma(total)= (264+-27) keV; Gamma(hadron)= (258+-26) keV, Gamma(mu)= (2.44+-0.21) keV, and Gamma(pi+pi- J/Psi)= (85+-8.7) keV; and Br(hadron)= (97.79+-0.15)%, Br(pi+pi- J/Psi)= (32+-1.4)%, Br(mu)= (0.93+-0.08)%, respectively.Comment: 8 pages, 6 figure

    Search for the Lepton Flavor Violation Processes J/ψJ/\psi \to μτ\mu\tau and eτe\tau

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    The lepton flavor violation processes J/ψμτJ/\psi \to \mu\tau and eτe\tau are searched for using a sample of 5.8×107\times 10^7 J/ψJ/\psi events collected with the BESII detector. Zero and one candidate events, consistent with the estimated background, are observed in J/ψμτ,τeνˉeντJ/\psi \to \mu\tau, \tau\to e\bar\nu_e\nu_{\tau} and J/ψeτ,τμνˉμντJ/\psi\to e\tau, \tau\to\mu\bar\nu_{\mu}\nu_{\tau} decays, respectively. Upper limits on the branching ratios are determined to be Br(J/ψμτ)<2.0×106Br(J/\psi\to\mu\tau)<2.0 \times 10^{-6} and Br(J/ψeτ)<8.3×106Br(J/\psi \to e\tau) < 8.3 \times10^{-6} at the 90% confidence level (C.L.).Comment: 9 pages, 2 figure

    Study of J/ψωK+KJ/\psi \to \omega K^+K^-

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    New data are presented on J/ψωK+KJ/\psi \to \omega K^+K^- from a sample of 58M J/ψJ/\psi events in the upgraded BES II detector at the BEPC. There is a conspicuous signal for f0(1710)K+Kf_0(1710) \to K^+K^- and a peak at higher mass which may be fitted with f2(2150)KKˉf_2(2150) \to K\bar K. From a combined analysis with ωπ+π\omega \pi ^+ \pi ^- data, the branching ratio BR(f0(1710)ππ)/BR(f0(1710)KKˉ)BR(f_0(1710)\to\pi\pi)/BR(f_0(1710) \to K\bar K) is <0.11< 0.11 at the 95% confidence level.Comment: 11 pages, 5 figures. Submitted to Phys. Lett.
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