3,032 research outputs found
Measurement of \psip Radiative Decays
Using 14 million psi(2S) events accumulated at the BESII detector, we report
first measurements of branching fractions or upper limits for psi(2S) decays
into gamma ppbar, gamma 2(pi^+pi^-), gamma K_s K^-pi^++c.c., gamma K^+ K^-
pi^+pi^-, gamma K^{*0} K^- pi^+ +c.c., gamma K^{*0}\bar K^{*0}, gamma pi^+pi^-
p pbar, gamma 2(K^+K^-), gamma 3(pi^+pi^-), and gamma 2(pi^+pi^-)K^+K^- with
the invariant mass of hadrons below 2.9GeV/c^2. We also report branching
fractions of psi(2S) decays into 2(pi^+pi^-) pi^0, omega pi^+pi^-, omega
f_2(1270), b_1^\pm pi^\mp, and pi^0 2(pi^+pi^-) K^+K^-.Comment: 5 pages, 4 figure
Measurements of and decays into and
Using 58 million and 14 million events collected by the
BESII detector at the BEPC, branching fractions or upper limits for the decays
and and are measured. For the isospin violating decays, the upper
limits are determined to be and at the 90% confidence level. The isospin
conserving process is observed for the
first time, and its branching fraction is measured to be , where the
first error is statistical and the second one is systematic. No signal is observed in decays, and is set at the 90%
confidence level. Branching fractions of decays into and are also reported, and the sum
of these branching fractions is determined to be .Comment: 7 pages, 10 figures. Phys.Rev.D comments considere
Observation of Y(2175) in
The decays of are analyzed using a sample of events collected with the BESII detector at the Beijing
Electron-Positron Collider (BEPC). A structure at around GeV/ with
about significance is observed in the invariant mass
spectrum. A fit with a Breit-Wigner function gives the peak mass and width of
GeV/ and GeV/, respectively, that are consistent with those
of Y(2175), observed by the BABAR collaboration in the initial-state radiation
(ISR) process . The production branching
ratio is determined to be , assuming that the Y(2175) is a state.Comment: 5 pages, 4 figures, accepted by Phys. Rev. Let
Is There a Classical Nonsense-Mediated Decay Pathway in Trypanosomes?
In many eukaryotes, messenger RNAs with premature termination codons are destroyed by a process called βnonsense-mediated decayβ, which requires the RNA helicase Upf1 and also, usually, an interacting factor, Upf2. Recognition of premature termination codons may rely on their distance from either a splice site or the polyadenylation site, and long 3β²-untranslated regions can trigger mRNA decay. The protist Trypanosoma brucei relies heavily on mRNA degradation to determine mRNA levels, and 3β²-untranslated regions play a major role in control of mRNA decay. We show here that trypanosomes have a homologue of Upf1, TbUPF1, which interacts with TbUPF2 and (in an RNA-dependent fashion) with poly(A) binding protein 1, PABP1. Introduction of a premature termination codon in either an endogenous gene or a reporter gene decreased mRNA abundance, as expected for nonsense-mediated decay, but a dependence of this effect on TbUPF1 could not be demonstrated, and depletion of TbUPF1 by over 95% had no effect on parasite growth or the mRNA transcriptome. Further investigations of the reporter mRNA revealed that increases in open reading frame length tended to increase mRNA abundance. In contrast, inhibition of translation, either using 5β²-secondary structures or by lengthening the 5β²-untranslated region, usually decreased reporter mRNA abundance. Meanwhile, changing the length of the 3β²-untranslated region had no consistent effect on mRNA abundance. We suggest that in trypanosomes, translation per se may inhibit mRNA decay, and interactions with multiple RNA-binding proteins preclude degradation based on 3β²-untranslated region length alone
Rationally designed transition metal hydroxide nanosheet arrays on graphene for artificial CO2 reduction
The performance of transition metal hydroxides, as cocatalysts for CO2 photoreduction, is significantly limited by their inherent weaknesses of poor conductivity and stacked structure. Herein, we report the rational assembly of a series of transition metal hydroxides on graphene to act as a cocatalyst ensemble for efficient CO2 photoreduction. In particular, with the Ru-dye as visible light photosensitizer, hierarchical Ni(OH)2 nanosheet arrays-graphene (Ni(OH)2-GR) composites exhibit superior photoactivity and selectivity, which remarkably surpass other counterparts and most of analogous hybrid photocatalyst system. The origin of such superior performance of Ni(OH)2-GR is attributed to its appropriate synergy on the enhanced adsorption of CO2, increased active sites for CO2 reduction and improved charge carriers separation/transfer. This work is anticipated to spur rationally designing efficient earth-abundant transition metal hydroxides-based cocatalysts on graphene and other two-dimension platforms for artificial reduction of CO2 to solar chemicals and fuels
Search for the C-parity violating process J/psi->gamma gamma via psi(2S)->pi+pi- J/psi
Using 14.0\times 10^6 \psi(2S) events collected with the BES-II detector, the
C-parity violating process J/psi->gamma gamma via psi(2S)->pi+pi- J/psi is
studied. We determine a new upper limit for the J/psi->gamma gamma branching
ratio of B(J/psi->gamma gamma)<2.2\times 10^{-5} at the 90% C.L., which is
about 20 times lower than the previous measurement.Comment: 4 pages 2 figure
Measurements of J/\psi decays into \omega K \bar{K} \pi and \phi K \bar{K} \pi
The decays of and are studied using events collected
with the Beijing Spectrometer (BESII) at the Beijing Electron-Positron Collider
(BEPC). The and systems,
produced in , have enhancements in the invariant
mass distributions at around 1.44 GeV/. However, there is no evidence
for mass enhancements in the system in . The branching fractions of , , , and are obtained, and the branching fraction is measured for the
first time.Comment: 18 pages, 10 figure
Expression of parvin-Ξ² is a prognostic factor for patients with urothelial cell carcinoma of the upper urinary tract
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