175 research outputs found
Observation of a ppb mass threshoud enhancement in \psi^\prime\to\pi^+\pi^-J/\psi(J/\psi\to\gamma p\bar{p}) decay
The decay channel
is studied using a sample of events collected
by the BESIII experiment at BEPCII. A strong enhancement at threshold is
observed in the invariant mass spectrum. The enhancement can be fit
with an -wave Breit-Wigner resonance function with a resulting peak mass of
and a
narrow width that is at the 90% confidence level.
These results are consistent with published BESII results. These mass and width
values do not match with those of any known meson resonance.Comment: 5 pages, 3 figures, submitted to Chinese Physics
Reemerging superconductivity at 48 K across quantum criticality in iron chalcogenides
Pressure plays an essential role in the induction1 and control2,3 of
superconductivity in iron-based superconductors. Substitution of a smaller
rare-earth ion for the bigger one to simulate the pressure effects has
surprisingly raised the superconducting transition temperature Tc to the record
high 55 K in these materials4,5. However, Tc always goes down after passing
through a maximum at some pressure and the superconductivity eventually tends
to disappear at sufficiently high pressures1-3. Here we show that the
superconductivity can reemerge with a much higher Tc after its destruction upon
compression from the ambient-condition value of around 31 K in newly discovered
iron chalcogenide superconductors. We find that in the second superconducting
phase the maximum Tc is as high as 48.7 K for K0.8Fe1.70Se2 and 48 K for
(Tl0.6Rb0.4)Fe1.67Se2, setting the new Tc record in chalcogenide
superconductors. The presence of the second superconducting phase is proposed
to be related to pressure-induced quantum criticality. Our findings point to
the potential route to the further achievement of high-Tc superconductivity in
iron-based and other superconductors.Comment: 20 pages and 7 figure
A Recombinant Vaccine of H5N1 HA1 Fused with Foldon and Human IgG Fc Induced Complete Cross-Clade Protection against Divergent H5N1 Viruses
Development of effective vaccines to prevent influenza, particularly highly pathogenic avian influenza (HPAI) caused by influenza A virus (IAV) subtype H5N1, is a challenging goal. In this study, we designed and constructed two recombinant influenza vaccine candidates by fusing hemagglutinin 1 (HA1) fragment of A/Anhui/1/2005(H5N1) to either Fc of human IgG (HA1-Fc) or foldon plus Fc (HA1-Fdc), and evaluated their immune responses and cross-protection against divergent strains of H5N1 virus. Results showed that these two recombinant vaccines induced strong immune responses in the vaccinated mice, which specifically reacted with HA1 proteins and an inactivated heterologous H5N1 virus. Both proteins were able to cross-neutralize infections by one homologous strain (clade 2.3) and four heterologous strains belonging to clades 0, 1, and 2.2 of H5N1 pseudoviruses as well as three heterologous strains (clades 0, 1, and 2.3.4) of H5N1 live virus. Importantly, immunization with these two vaccine candidates, especially HA1-Fdc, provided complete cross-clade protection against high-dose lethal challenge of different strains of H5N1 virus covering clade 0, 1, and 2.3.4 in the tested mouse model. This study suggests that the recombinant fusion proteins, particularly HA1-Fdc, could be developed into an efficacious universal H5N1 influenza vaccine, providing cross-protection against infections by divergent strains of highly pathogenic H5N1 virus
Molecular Characterization of Highly Pathogenic H5N1 Avian Influenza A Viruses Isolated from Raccoon Dogs in China
The highly pathogenic avian influenza H5N1 virus can infect a variety of animals and continually poses a threat to animal and human health. While many genotypes of H5N1 virus can be found in chicken, few are associated with the infection of mammals. Characterization of the genotypes of viral strains in animal populations is important to understand the distribution of different viral strains in various hosts. This also facilitates the surveillance and detection of possible emergence of highly pathogenic strains of specific genotypes from unknown hosts or hosts that have not been previously reported to carry these genotypes.Two H5N1 isolates were obtained from lung samples of two raccoon dogs that had died from respiratory disease in China. Pathogenicity experiments showed that the isolates were highly pathogenic to chicken. To characterize the genotypes of these viruses, their genomic sequences were determined and analyzed. The genetic contents of these isolates are virtually identical and they may come from the same progenitor virus. Phylogenetic analysis indicated that the isolates were genetically closely related to genotype V H5N1 virus, which was first isolated in China in 2003, and were distinct from the dominant virus genotypes (e.g. genotype Z) of recent years. The isolates also contain a multibasic amino acid motif at their HA cleavage sites and have an E residue at position 627 of the PB2 protein similar to the previously-identified avian viruses.This is the first report that genotype V H5N1 virus is found to be associated with a mammalian host. Our results strongly suggest that genotype V H5N1 virus has the ability to cross species barriers to infect mammalian animals. These findings further highlight the risk that avian influenza H5N1 virus poses to mammals and humans, which may be infected by specific genotypes that are not known to infect these hosts
Experimental studies of e + e -β some charmless processes containing K S0 at βs = 3.773 and 3.65 GeV
We measure the observed cross sections for the charmless processes e + e -βK S0 K - K - K + Ο ++ c.c., K S0 K - Ο + Ξ·+c.c., K S0 K - Ο + Ο + Ο - Ξ·+c.c., K S0 K - K - K + Ο + Ξ·+c.c., K S0 K - K - K + Ο + Ο 0+c.c., K S0 K - Ο ++c.c. and K S0 K - Ο + Ο 0+c.c. We also extract upper limits on the branching fractions for Ο(3770) decays into these final states at 90% C.L. Analyzed data samples correspond to 17.3 pb-1 and 6.5 pb-1 integrated luminosities registered, respectively, at βs = 3.773 and 3.65 GeV, with the BES-II detector at the BEPC collider. Β© 2009 Springer-Verlag / SocietΓ Italiana di Fisica.published_or_final_versionSpringer Open Choice, 21 Feb 201
Search for Ο(3770)β charmless final states involving Ξ· or Ο0 mesons
We search for Ο(3770) β Ο+Ο-Ξ·, K+K-Ξ·, ppΜΞ·, Ο0Ο+Ο-Ξ·, K+K-Ο+Ο-Ξ·, ppΜΟ+Ο-Ξ·, ppΜK+K-Ξ· and ppΜK+K- Ο0 using data samples of 17.3 and 6.5 pb-1 integrated luminosities recorded at the center-of-mass energies of 3.773 and 3.65 GeV, respectively, by the BES-II detector operating at the BEPC collider. We obtain cross section measurements at both energies and upper limits on Ο(3770) decay branching fractions to the final states studied. Β© Β© Springer-Verlag / SocietΓ Italiana di Fisica 2010.published_or_final_versionSpringer Open Choice, 21 Feb 201
Measurement of electron antineutrino oscillation based on 1230Β days of operation of the Daya Bay experiment
published_or_final_versio
Improved Search for a Light Sterile Neutrino with the Full Configuration of the Daya Bay Experiment
published_or_final_versio
Improved measurement of the reactor antineutrino flux and spectrum at Daya Bay
published_or_final_versio
Independent measure of the neutrino mixing angle ΞΈ13 via neutron capture on hydrogen at Daya Bay
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