We report a study of the processes of e^{+}e^{-}→K^{+}D_{s}^{-}D^{*0} and K^{+}D_{s}^{*-}D^{0} based on e^{+}e^{-} annihilation samples collected with the BESIII detector operating at BEPCII at five ...center-of-mass energies ranging from 4.628 to 4.698 GeV with a total integrated luminosity of 3.7 fb^{-1}. An excess of events over the known contributions of the conventional charmed mesons is observed near the D_{s}^{-}D^{*0} and D_{s}^{*-}D^{0} mass thresholds in the K^{+} recoil-mass spectrum for events collected at sqrts=4.681 GeV. The structure matches a mass-dependent-width Breit-Wigner line shape, whose pole mass and width are determined as (3982.5_{-2.6}^{+1.8}±2.1) MeV/c^{2} and (12.8_{-4.4}^{+5.3}±3.0) MeV, respectively. The first uncertainties are statistical and the second are systematic. The significance of the resonance hypothesis is estimated to be 5.3 σ over the contributions only from the conventional charmed mesons. This is the first candidate for a charged hidden-charm tetraquark with strangeness, decaying into D_{s}^{-}D^{*0} and D_{s}^{*-}D^{0}. However, the properties of the excess need further exploration with more statistics.
Based on a sample of 1.31×10^{9} J/ψ events collected with the BESIII detector, an amplitude analysis of the isospin-violating decays η^{'}→π^{+}π^{-}π^{0} and η^{'}→π^{0}π^{0}π^{0} is performed. A ...significant P-wave contribution from η^{'}→ρ^{±}π^{∓} is observed for the first time in η^{'}→π^{+}π^{-}π^{0}. The branching fraction is determined to be B(η^{'}→ρ^{±}π^{∓})=(7.44±0.60±1.26±1.84)×10^{-4}, where the first uncertainty is statistical, the second systematic, and the third model dependent. In addition to the nonresonant S-wave component, there is a significant σ meson component. The branching fractions of the combined S-wave components are determined to be B(η^{'}→π^{+}π^{-}π^{0})_{S}=(37.63±0.77±2.22±4.48)×10^{-4} and B(η^{'}→π^{0}π^{0}π^{0})=(35.22±0.82±2.54)×10^{-4}, respectively. The latter one is consistent with previous BESIII measurements.
Summary
Studies regarding the clinical significance of quantitative hepatitis B core antibody (anti‐HBc) in patients with chronic hepatitis B receiving first‐line nucleos(t)ide analogues is limited. ...The aim of this study was to determine the performance of anti‐HBc as a predictor for hepatitis B e antigen (HBeAg) seroconversion in HBeAg‐positive CHB patients treated with entecavir. This was a retrospective cohort study consisting of 139 Chinese patients enrolled in a multicenter clinical trial treated with entecavir or entecavir maleate for up to 240 weeks. Anti‐HBc evaluation was conducted for all the available samples using a newly developed double‐sandwich anti‐HBc immunoassay. At week 240, 35 (25.2%) patients achieved a serological response (HBeAg seroconversion) and these patients at week 240 had significantly higher levels of anti‐HBc (P<.01). We defined 4.65 log10 IU·mL−1, with a maximum sum of sensitivity and specificity, as the optimal cut‐off value of baseline anti‐HBc level to predict seroconversion. Patients with baseline anti‐HBc ≥4.65 log10 IU·mL−1 had 28.0% (26/93) and 35.5% (33/93) chance of seroconversion at weeks 144 and 240, respectively. The baseline anti‐HBc level was the strongest predictor for seroconversion at week 144 (OR: 5.78, 95% confidence interval CI: 2.05‐16.34, P=.001). The baseline anti‐HBc level was a strong predictor for seroconversion at week 240 (OR: 5.36, 95% CI: 2.17‐13.25, P<.001). Hence, baseline anti‐HBc titre is a useful predictor of long‐term entecavir therapy efficacy in HBeAg‐positive CHB patients, which could be used to optimize antiviral therapy.
On 10 September 2017, irradiance from a magnitude X8.2 solar flare impacted Mars while the Mars Atmosphere and Volatile EvolutioN (MAVEN) orbiter was characterizing the Mars upper atmosphere. This ...solar flare was the largest to occur during the MAVEN mission to date, nearly tripling the ionizing irradiance impacting Mars in tens of minutes, and provides an opportunity to study the planet's response to extreme irradiance changes. This letter reports in situ observations of the Mars topside ionosphere's response to this flare above 155 km made 1.67 hr after the flare soft X‐ray peak. The observed plasma density increase is higher than expected based solely on increased ionization, and the electron temperature decreases below 225 km; both effects can be explained by an expanded neutral atmosphere, which efficiently dissipates any flare‐induced heating of the thermal electrons at altitudes where CO2 is the dominant species. Further, the ion density and composition change significantly at both fixed altitude and pressure level, which can be explained by a change in the O:CO2 density ratio, highlighting the importance this ratio has in determining ionospheric structure.
Plain Language Summary
On 10 September 2017, a large solar flare erupted from the Sun sending intense radiation into the upper atmosphere of Mars. This radiation ionized the gases in Mars's upper atmosphere, resulting in significant changes in its structure and composition. Because solar flares are short‐lived events, studying how the Mars atmosphere responds to them can unmask phenomena that may otherwise be hidden when the Sun varies more gradually. This letter reports the first in situ observations of the how the ions and electrons in the Mars upper atmosphere, above 155 km, change during solar flares. This region of the atmosphere interfaces with the space environment, where it can be stripped away and lost. The rate of loss is believed to be strongly dependent on the same radiation released by flares. Therefore, understanding how Mars responds to flares can provide insight into how its atmosphere evolved early in its history, when the Sun is believed to have produced larger flares more frequently, and Mars is believed to have had an atmosphere capable of supporting large amounts of liquid water. In addition to Mars researchers, these results will be of particular interest to those studying space weather, planetary atmospheres, and the habitability of exoplanets.
Key Points
Ionizing EUV flux increased by 170% at the flare peak, causing changes in the observed (>150 km) plasma density, temperature, and composition
Ionospheric changes are a result of an expanded neutral atmosphere, and the increased relative abundance of O at fixed pressure level
Photochemical escape of O increased moderately for observations made 80 min after the flare peak
•The nanoscale structural heterogeneity was analyzed by small-angle X-ray scattering and atomic force microscopy.•The microalloying of Co and Ni exhibits an opposite effect on the nanoscale ...structural heterogeneity.•The variation of mechanical behavior further proves the evolution of the nanoscale structural heterogeneity with Co and Ni substitution.•The evolution of magnetic properties induced by microalloying can be attributed to the variation of nanoscale structural heterogeneity.
Nanoscale structural heterogeneity is a critical parameter for understanding the structure-property relationships in amorphous alloys. Herein, the small-angle X-ray scattering and atomic force microscopy were utilized to quantitatively investigate the nanoscale structural heterogeneity of the Fe80-xMxSi9B11 (M = Co and Ni; x = 0, 2, 4) amorphous alloys. The results show that the nanoscale structural heterogeneity of the amorphous alloys increases prominently with Ni substitution, but gradually decreases with the increase of Co content. Such evolution of structural heterogeneity was further verified by the changes in mechanical behavior. The microalloying of Ni can increase the plastic deformation ability and reduce the microhardness, whereas an opposite effect is found in the Co-doped alloys. Finally, Mössbauer spectroscopy reveals an enhancement in ferromagnetic exchange interaction and magnetic anisotropy with Co substitution, while the microalloying of Ni leads to a deteriorative result. Such variations in magnetic properties can be attributed to the evolution of nanoscale structural heterogeneity with Co and Ni additions. Our observation serves as a link between the nanoscale structural heterogeneity and magnetic properties, providing a new sight into understanding the structural origin of the changes in magnetic properties of Fe-based amorphous alloys.
The rare decay η ′ → π+ π− e+ e− is studied using a sample of 1.3 × 109 J / ψ events collected with the BESIII detector at BEPCII in 2009 and 2012. The branching fraction is measured with improved ...precision to be ( 2.42 ± 0.0 5stat ± 0.0 8syst) × 10−3. Due to the inclusion of new data, this result supersedes the last BESIII result on this branching fraction. In addition, the C P -violating asymmetry in the angle between the decay planes of the π+π− -pair and the e+e− -pair is investigated. A measurable value would indicate physics beyond the standard model; the result is ACP = ( 2.9 ± 3. 7stat ± 1. 1syst) % , which is consistent with the standard model expectation of no C P -violation. The precision is comparable to the asymmetry measurement in the K0L → π+π− e+e− decay where the observed (14 ± 2) % effect is driven by a standard model mechanism.
We present the improved constraints on couplings of solar axions and more generic bosonic dark matter particles using 737.1 kg days of data from the CDEX-1B experiment. The CDEX-1B experiment, ...located at the China Jinping Underground Laboratory, primarily aims at the direct detection of weakly interacting massive particles using a p-type point-contact germanium detector. We adopt the profile likelihood ratio method for analysis of data in the presence of backgrounds. An energy threshold of 160 eV was achieved, much better than the 475 eV of CDEX-1A with an exposure of 335.6 kg days. This significantly improves the sensitivity for the bosonic dark matter below 0.8 keV among germanium detectors. Limits are also placed on the coupling gAe < 2.48 × 10−11 from Compton, bremsstrahlung, atomic-recombination, and deexcitation channels and geffAN × gAe < 4.14 × 10−17 from a 57Fe M1 transition at 90% confidence level.
Summary
Reports on the efficacy and safety of long‐term entecavir treatment in chronic hepatitis B (CHB) predominantly genotype B or C are insufficient. This study presents the efficacy and safety of ...entecavir maleate in Chinese CHB patients. Patients were randomly assigned to receive 48‐week treatment with either 0.5 mg/day entecavir (group A) or 0.5 mg/day entecavir maleate (group B), and then all patients received treatment with 0.5 mg/day entecavir maleate from week 49. Two hundred and seventy‐five patients with CHB (HBeAg‐positive: 218) were analysed, predominantly (98.5%) with genotype B or C. Baseline characteristics were balanced. For the HBeAg‐positive CHB patients, the mean HBV DNA level decreased similarly (A: by 6.36 log10 IU/mL vs B: by 6.31 log10 IU/mL) between groups at week 144. The percentages of patients who achieved undetectable HBV DNA were similar (A: 70.59% vs B: 66.67%) between groups. Similar HBeAg loss rates (A: 43.53% vs B: 40.23%; P>.05) and HBeAg seroconversion rates (A: 21.52% vs B: 21.18%) were achieved. For the HBeAg‐negative CHB patients, similar reductions in HBV DNA levels from baseline (A: by 6.13 log10 IU/mL vs B: by 5.65 log10 IU/mL) and percentages of patients who achieved undetectable HBV DNA (A: 100% vs B: 100%) were achieved. The overall incidence of adverse events was comparable between groups. In conclusions, 48‐week administration of entecavir maleate and entecavir showed similar efficacy and safety in Chinese patients with CHB. Long‐term entecavir maleate treatment was effective and safe in CHB patients.
•A Neumann boundary scheme is proposed for thermal flows with heat flux at the interface.•Only lattice link interpolation involved contributes to an easy implementation procedure.•Fully second-order ...accuracy can be achieved for complex geometries.•Versatility and efficiency of present scheme is validated in the simulations.
We propose a curved lattice Boltzmann boundary scheme for thermal convective flows with Neumann boundary condition. The distribution function at the fluid-solid intersection node is obtained to accomplish the interpolation of unknown temperature distribution function at the boundary point. Specifically, the distribution function is first extrapolated from the fluid point along the lattice link; and then, the one in the opposite direction is evaluated by the anti-bounce back rule with wall temperature, which can be further determined by the specified Neumann boundary condition at the fluid-solid interface. The advantage of our scheme is that the involved inter/extrapolations are completely link-based, resulting in a quite efficient implementation procedure. Furthermore, our scheme has second-order spatial accuracy, and we verified in four numerical examples where analytical solutions are available: the heat transfer in a channel with a sinusoidal temperature gradient, the thermal diffusion in an annulus, and the conjugate heat transfer for these two cases. To further validate our scheme for thermal convective flow problems with complex geometries, we simulate the natural convection in an annulus, the thermal flow past a cylinder, and the mixed convection in a lid-driven cavity with a circular enclosure. The simulation results are consistent with existing benchmark data obtained by other methods.
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