22 research outputs found
Pressure effects on superconducting properties of single-crystalline Co doped NaFeAs
Resistivity and magnetic susceptibility measurements under external pressure
were performed on single-crystals NaFe1-xCoxAs (x=0, 0.01, 0.028, 0.075,
0.109). The maximum Tc enhanced by pressure in both underdoped and optimally
doped NaFe1-xCoxAs is the same, as high as 31 K. The overdoped sample with x =
0.075 also shows a positive pressure effect on Tc, and an enhancement of Tc by
13 K is achieved under pressure of 2.3 GPa. All the superconducting samples
show large positive pressure coefficient on superconductivity, being different
from Ba(Fe1-xCox)2As2. However, the superconductivity cannot be induced by
pressure in heavily overdoped non-superconducting NaFe0.891Co0.109As. These
results provide evidence for that the electronic structure is much different
between superconducting and heavily overdoped non-superconducting NaFe1-xCoxAs,
being consistent with the observation by angle-resolved photoemission
spectroscopy.Comment: 6 pages, 6 figure
Measurement of decays to baryon pairs
A sample of 3.95M decays registered in the BES detector are used
to study final states containing pairs of octet and decuplet baryons. We report
branching fractions for , ,
, ,
, ,
, and . These results
are compared to expectations based on the SU(3)-flavor symmetry, factorization,
and perturbative QCD.Comment: 22 pages, 21 figures, 4 table
Measurement of the Total Cross Section for Hadronic Production by e+e- Annihilation at Energies between 2.6-5 Gev
Using the upgraded Beijing Spectrometer (BESII), we have measured the total
cross section for annihilation into hadronic final states at
center-of-mass energies of 2.6, 3.2, 3.4, 3.55, 4.6 and 5.0 GeV. Values of ,
, are determined.Comment: Submitted to Phys. Rev. Let
Measurement of the Inclusive Charm Cross Section at 4.03 GeV and 4.14 GeV
The cross section for charmed meson production at and 4.14
GeV has been measured with the Beijing Spectrometer. The measurement was made
using 22.3 of data collected at 4.03 GeV and 1.5
of data collected at 4.14 GeV. Inclusive observed cross sections for
the production of charged and neutral D mesons and momentum spectra are
presented. Observed cross sections were radiatively corrected to obtain tree
level cross sections. Measurements of the total hadronic cross section are
obtained from the charmed meson cross section and an extrapolation of results
from below the charm threshold.Comment: 11 pages, 13 figures. The top level tex file is paper.tex. It builds
the paper from other tex files in this .tar and the .eps file
A Measurement of the Mass and Full-Width of the Meson
In a sample of 7.8 million decays collected in the Beijing
Spectrometer, the process J/ is observed for five
different decay channels: , ,
(with ), (with ) and . From these signals, we determine the mass of
to be MeV. Combining this result with a
previously reported result from a similar study using
detected in the same spectrometer gives MeV.
For the combined samples, we obtain MeV.Comment: 4 pages, 3 figures and 1 tabl
Psi(2S) -> pi^+ pi^- J/psi Decay Distributions
Using a sample of 3.8 M psi(2S) events accumulated with the BES detector, the
process psi(2S) -> pi^+ pi^- J/psi is studied. The angular distributions are
compared with the general decay amplitude analysis of Cahn. We find that the
dipion system requires some D-wave, as well as S-wave. On the other hand, the
J/psi-(pi pi) relative angular momentum is consistent with being pure S-wave.
The decay distributions have been fit to heavy quarkonium models, including the
Novikov-Shifman model. This model, which is written in terms of the parameter
kappa, predicts that D-wave should be present. We determine kappa = 0.183 +/-
0.002 +/- 0.003 based on the joint dipion mass - cos theta distribution. The
fraction of D-wave as a function of the dipion mass is found to decrease with
increasing dipion mass, in agreement with the model. We have also fit the
Mannel-Yan model, another model that allows D-wave.Comment: 21 pages, 10 figure
Study of the Hadronic Decays of \chi_c States
Hadronic decays of the P-wave spin-triplet charmonium states \chi_cJ
(J=0,1,2) are studied using a sample of \psi(2S) decays collected by the BES
detector operating at the BEPC storage ring. Branching fractions for the decays
\chi_c1 going to K_s^0 K^+ \pi^- + c.c., \chi_c0 going to K_s^0 K_s^0, \chi_c2
going to K_s^0 K_s^0, \chi_c0 going to \phi \phi, \chi_c2 going to \phi \phi
and \chi_cJ going to K^+ K^- K^+ K^- are measured for the first time, and those
for \chi_cJ going to \pi^+ \pi^- \pi^+ \pi^-, $ \chi_cJ going to \pi^+ \pi^-
K^+ K^-, \chi_cJ going to \pi^+ \pi^- p \bar{p} and \chi_cJ going to 3(\pi^+
\pi^-) are measured with improved precision. In addition, we determine the
masses of the \chi_c0 and \eta_c to be M_{\chi_{c0}}=3414.1 \pm 0.6(stat) \pm
0.8 (sys) MeV and M_{\eta_c}=2975.8 \pm 3.9(stat) \pm 1.2 (sys) MeV.Comment: 24 pages, 12 figures, 6 tables, use revtex, submitted to Phys. Rev.
Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)
In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field