Xuyang Gao

We describe an ultra-wide-bandwidth, low-frequency receiver ("UWL") recently installed on the Parkes radio telescope. The receiver system provides continuous frequency coverage from 704 to 4032 MHz. For much of the band (~60%) the system temperature is approximately 22K and the receiver system remains in a linear regime even in the presence of strong mobile phone transmissions. We discuss the scientific and technical aspects of the new receiver including its astronomical objectives, as well as the feed, receiver, digitiser and signal-processor design. We describe the pipeline routines that form the archive-ready data products and how those data files can be accessed from the archives. The system performance is quantified including the system noise and linearity, beam shape, antenna efficiency, polarisation calibration and timing stability.

Using a data sample collected with the BESIII detector operating at the BEPCII storage ring, we observe a new neutral state Z_{c}(3900)^{0} with a significance of 10.4σ. The mass and width are measured to be 3894.8±2.3±3.2 MeV/c^{2} and 29.6±8.2±8.2 MeV, respectively, where the first error is statistical and the second systematic. The Born cross section for e^{+}e^{-}→π^{0}π^{0}J/ψ and the fraction of it attributable to π^{0}Z_{c}(3900)^{0}→π^{0}π^{0}J/ψ in the range E_{c.m.}=4.19-4.42 GeV are also determined. We interpret this state as the neutral partner of the four-quark candidate Z_{c}(3900)^{±}.

The spin and parity of the $Z_c(3900)^\pm$ state are determined to be $J^P=1^+$ with a statistical significance larger than $7\sigma$ over other quantum numbers in a partial wave analysis of the process $e^+e^-\to \pi^+\pi^-J/\psi$. We use a data sample of 1.92 fb$^{-1}$ accumulated at $\sqrt{s}=4.23$ and 4.26 GeV with the BESIII experiment. When parameterizing the $Z_c(3900)^\pm$ with a Flatte-like formula, we determine its pole mass $M_\textrm{pole}=(3881.2\pm4.2_\textrm{stat}\pm52.7_\textrm{syst})\textrm{MeV}/c^2$ and pole width $\Gamma_\textrm{pole}=(51.8\pm4.6_\textrm{stat}\pm36.0_\textrm{syst})\textrm{MeV}$. We also measure cross sections for the process $e^+e^-\to Z_c(3900)^+\pi^-+c.c.\to J/\psi\pi^+\pi^-$ and determine an upper limit at the 90\% confidence level for the process $e^+e^-\to Z_c(4020)^+\pi^-+c.c.\to J/\psi\pi^+\pi^-$.

From 2011 to 2014, the BESIII experiment collected about 5 fb−1 data at center-of-mass energies around 4 GeV for the studies of the charmonium-like and higher excited charmonium states. By analyzing the di-muon process e+e− → γISR/FSRμ+μ−, the center-of-mass energies of the data samples are measured with a precision of 0.8 MeV. The center-of-mass energy is found to be stable for most of the time during data taking.

In an analysis of a $2.92\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ data sample taken at 3.773 GeV with the BESIII detector operated at the BEPCII collider, we measure the absolute decay branching fractions $\mathcal{B}({D}^{0}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{e}^{+}{\ensuremath{\nu}}_{e})=(3.505\ifmmode\pm\else\textpm\fi{}0.014\ifmmode\pm\else\textpm\fi{}0.033)%$ and $\mathcal{B}({D}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}{e}^{+}{\ensuremath{\nu}}_{e})=(0.295\ifmmode\pm\else\textpm\fi{}0.004\ifmmode\pm\else\textpm\fi{}0.003)%$. From a study of the differential decay rates we obtain the products of hadronic form factor and the magnitude of the Cabibbo-Kobayashi- Maskawa (CKM) matrix element ${f}_{+}^{K}(0)|{V}_{cs}|=0.7172\ifmmode\pm\else\textpm\fi{}0.0025\ifmmode\pm\else\textpm\fi{}0.0035$ and ${f}_{+}^{\ensuremath{\pi}}(0)|{V}_{cd}|=0.1435\ifmmode\pm\else\textpm\fi{}\phantom{\rule{0ex}{0ex}}0.0018\ifmmode\pm\else\textpm\fi{}0.0009$. Combining these products with the values of $|{V}_{cs(d)}|$ from the SM constraint fit, we extract the hadronic form factors ${f}_{+}^{K}(0)=0.7368\ifmmode\pm\else\textpm\fi{}0.0026\ifmmode\pm\else\textpm\fi{}0.0036$ and ${f}_{+}^{\ensuremath{\pi}}(0)=0.6372\ifmmode\pm\else\textpm\fi{}0.0080\ifmmode\pm\else\textpm\fi{}\phantom{\rule{0ex}{0ex}}0.0044$, and their ratio ${f}_{+}^{\ensuremath{\pi}}(0)/{f}_{+}^{K}(0)=0.8649\ifmmode\pm\else\textpm\fi{}0.0112\ifmmode\pm\else\textpm\fi{}0.0073$. These form factors and their ratio are used to test unquenched lattice QCD calculations of the form factors and a light cone sum rule (LCSR) calculation of their ratio. The measured value of ${f}_{+}^{K(\ensuremath{\pi})}(0)|{V}_{cs(d)}|$ and the lattice QCD value for ${f}_{+}^{K(\ensuremath{\pi})}(0)$ are used to extract values of the CKM matrix elements of $|{V}_{cs}|=0.9601\ifmmode\pm\else\textpm\fi{}0.0033\ifmmode\pm\else\textpm\fi{}0.0047\ifmmode\pm\else\textpm\fi{}0.0239$ and $|{V}_{cd}|=0.2155\ifmmode\pm\else\textpm\fi{}0.0027\ifmmode\pm\else\textpm\fi{}0.0014\ifmmode\pm\else\textpm\fi{}0.0094$, where the third errors are due to the uncertainties in lattice QCD calculations of the form factors. Using the LCSR value for ${f}_{+}^{\ensuremath{\pi}}(0)/{f}_{+}^{K}(0)$, we determine the ratio $|{V}_{cd}|/|{V}_{cs}|=0.238\ifmmode\pm\else\textpm\fi{}0.004\ifmmode\pm\else\textpm\fi{}0.002\ifmmode\pm\else\textpm\fi{}0.011$, where the third error is from the uncertainty in the LCSR normalization. In addition, we measure form factor parameters for three different theoretical models that describe the weak hadronic charged currents for these two semileptonic decays. All of these measurements are the most precise to date.

We study the spectral and polarization properties of supernova remnants (SNRs) based on our 6cm survey data. The observations were taken from the Sino-German 6cm polarization survey of the Galactic plane. By using the integrated flux densities at 6cm together with measurements at other wavelengths from the literature we derive the global spectra of 50 SNRs. In addition, we use the observations at 6cm to present the polarization images of 24 SNRs. We derived integrated flux densities at 6cm for 51 small SNRs with angular sizes less than 1 degree. Global radio spectral indices were obtained in all the cases except for Cas A. For SNRs G15.1-1.6, G16.2-2.7, G16.4-0.5, G17.4-2.3, G17.8-2.6, G20.4+0.1, G36.6+2.6, G43.9+1.6, G53.6-2.2, G55.7+3.4, G59.8+1.2, G68.6-1.2, and G113.0+0.2, the spectra have been significantly improved. From our analysis we argue that the object G16.8-1.1 is probably an HII region instead of a SNR. Cas A shows a secular decrease in total intensity, and we measured a flux density of 688+/-35 Jy at 6cm between 2004 and 2008. Polarized emission from 25 SNRs were detected. For G16.2-2.7, G69.7+1.0, G84.2-0.8 and G85.9-0.6, the polarized emission is detected for the first time confirming them as SNRs. High frequency observations of SNRs are rare but important to establish their spectra and trace them in polarization in particular towards the inner Galaxy where Faraday effects are important.

A neutral structure in the DD[over ¯]^{*} system around the DD[over ¯]^{*} mass threshold is observed with a statistical significance greater than 10σ in the processes e^{+}e^{-}→D^{+}D^{*-}π^{0}+c.c. and e^{+}e^{-}→D^{0}D[over ¯]^{*0}π^{0}+c.c. at sqrt[s]=4.226 and 4.257 GeV in the BESIII experiment. The structure is denoted as Z_{c}(3885)^{0}. Assuming the presence of a resonance, its pole mass and width are determined to be [3885.7_{-5.7}^{+4.3}(stat)±8.4(syst)] MeV/c^{2} and [35_{-12}^{+11}(stat)±15(syst)] MeV, respectively. The Born cross sections are measured to be σ[e^{+}e^{-}→Z_{c}(3885)^{0}π^{0},Z_{c}(3885)^{0}→DD[over ¯]^{*}]=[77±13(stat)±17(syst)] pb at 4.226 GeV and [47±9(stat)±10(syst)] pb at 4.257 GeV. The ratio of decay rates B[Z_{c}(3885)^{0}→D^{+}D^{*-}+c.c.]/B[Z_{c}(3885)^{0}→D^{0}D[over ¯]^{*0}+c.c.] is determined to be 0.96±0.18(stat)±0.12(syst), consistent with no isospin violation in the process, Z_{c}(3885)^{0}→DD[over ¯]^{*}.

A measurement of the number of $J/\psi$ events collected with the BESIII detector in 2009 and 2012 is performed using inclusive decays of the $J/\psi$ . The number of $J/\psi$ events taken in 2009 is recalculated to be $(223.7\pm1.4)\times 10^6$, which is in good agreement with the previous measurement, but with significantly improved precision due to improvements in the BESIII software. The number of $J/\psi$ events taken in 2012 is determined to be $(1086.9\pm 6.0)\times 10^6$. In total, the number of $J/\psi$ events collected with the BESIII detector is measured to be $(1310.6\pm 7.0)\times 10^6$, where the uncertainty is dominated by systematic effects and the statistical uncertainty is negligible.

<i>Context. <i/>Linearly polarized Galactic synchrotron emission provides valuable information about the properties of the Galactic magnetic field and the interstellar magneto-ionic medium, when Faraday rotation along the line of sight is properly taken into account.<i>Aims. <i/>We aim to survey the Galactic plane at <i>λ<i/>6 cm including linear polarization. At such a short wavelength Faraday rotation effects are in general small and the Galactic magnetic field properties can be probed to larger distances than at long wavelengths.<i>Methods. <i/>The Urumqi 25-m telescope is used for a sensitive <i>λ<i/>6 cm survey in total and polarized intensities. WMAP K-band (22.8 GHz) polarization data are used to restore the absolute zero-level of the Urumqi <i>U<i/> and <i>Q<i/> maps by extrapolation.<i>Results. <i/>Total intensity and polarization maps are presented for a Galactic plane region of 129° <i>≤<i/> <i>≤<i/> 230° and |<i>b<i/>| <i>≤<i/> 5° in the anti-centre with an angular resolution of and an average sensitivity of 0.6 mK and 0.4 mK <i>T<i/><sub>B<sub/> in total and polarized intensity, respectively. We briefly discuss the properties of some extended Faraday Screens detected in the <i>λ<i/>6 cm polarization maps.<i>Conclusions. <i/>The Sino-German <i>λ<i/>6 cm polarization survey provides new information about the properties of the magnetic ISM. The survey also adds valuable information for discrete Galactic objects and is in particular suited to detect extended Faraday Screens with large rotation measures hosting strong regular magnetic fields.

We present a measurement of the azimuthal asymmetries of two charged pions in the inclusive process e^{+}e^{-}→ππX, based on a data set of 62 pb^{-1} at the center-of-mass energy of 3.65 GeV collected with the BESIII detector. These asymmetries can be attributed to the Collins fragmentation function. We observe a nonzero asymmetry, which increases with increasing pion momentum. As our energy scale is close to that of the existing semi-inclusive deep inelastic scattering experimental data, the measured asymmetries are important inputs for the global analysis of extracting the quark transversity distribution inside the nucleon and are valuable to explore the energy evolution of the spin-dependent fragmentation function.

We report the first observation of the Dalitz decay $\eta' \to \gamma e^+e^-$, based on a data sample of 1.31 billion $J/\psi$ events collected with the BESIII detector. The $\eta'$ mesons are produced via the $J/\psi \to \gamma \eta'$ decay process. The ratio $\Gamma(\eta' \to \gamma e^+ e^-)/\Gamma(\eta'\to\gamma\gamma)$ is measured to be $(2.13\pm0.09(\text{stat.})\pm0.07(\text{sys.}))\times10^{-2}$. This corresponds to a branching fraction ${\cal B}(\eta' \to \gamma e^+e^-)= (4.69 \pm0.20(\text{stat.})\pm0.23(\text{sys.}))\times10^{-4}$. The transition form factor is extracted and different expressions are compared to the measured dependence on the $e^+e^-$ invariant mass. The results are consistent with the prediction of the Vector Meson Dominance model.

By analyzing 2.93 fb $$^{-1}$$ of data collected at $$\sqrt{s}=3.773$$ GeV with the BESIII detector, we measure the absolute branching fraction $${\mathcal B}(D^{+}\rightarrow \bar{K}^0\mu ^{+}\nu _{\mu })=(8.72 \pm 0.07_\mathrm{stat.} \pm 0.18_\mathrm{sys.})\%$$ , which is consistent with previous measurements within uncertainties but with significantly improved precision. Combining the Particle Data Group values of $${\mathcal B}(D^0\rightarrow K^-\mu ^+\nu _\mu )$$ , $${\mathcal B}(D^{+}\rightarrow \bar{K}^0 e^{+}\nu _{e})$$ , and the lifetimes of the $$D^0$$ and $$D^+$$ mesons with the value of $${\mathcal B}(D^{+}\rightarrow \bar{K}^0 \mu ^{+}\nu _{\mu })$$ measured in this work, we determine the following ratios of partial widths: $$\Gamma (D^0\rightarrow K^-\mu ^+\nu _\mu )/\Gamma (D^{+}\rightarrow \bar{K}^0\mu ^{+}\nu _{\mu })=0.963\pm 0.044$$ and $$\Gamma (D^{+}\rightarrow \bar{K}^0 \mu ^{+}\nu _{\mu })/\Gamma (D^{+}\rightarrow \bar{K}^0 e^{+}\nu _{e})=0.988\pm 0.033$$ .

The influence of bar reinforcement and the concrete strength on shear properties of new-to-old interface is investigated in this work. Two failure modes of brittle failure (plain concrete) and plastic failure (reinforced concrete) are observed in the test. The amount of steel bars and concrete strength have a strong effect on the failure mode, while the distribution law of the reinforcement bars has almost no influence on the failure mode. Interface shear strength is mainly provided by the bonding force of the new-to-old concrete and the shear resistance of the embedded steel bar. However, the vertical friction force generated by the tensile force of the embedded steel bar has the least influence on the interface shear strength. Based on the micro-damage mechanism of new-to-old concrete interface under condition of reinforcement planting, a damage prediction model of new-to-old concrete interface is proposed in this article. The model can be used to predict the damage degree of new-to- old concrete interface subjected to different planting areas.

Using data samples collected with the BESIII detector operating at the BEPCII collider at center-of-mass energies from 3.810 to 4.600 GeV, we perform a study of $e^{+}e^{-} \to \eta J/\psi$ and $\pi^0 J/\psi$. Statistically significant signals of $e^{+}e^{-} \to \eta J/\psi$ are observed at $\sqrt{s}$ = 4.190, 4.210, 4.220, 4.230, 4.245, 4.260, 4.360 and 4.420 GeV, while no signals of $e^{+}e^{-} \to \pi^{0} J/\psi$ are observed. The measured energy-dependent Born cross section for $e^{+}e^{-} \to \eta J/\psi$ shows an enhancement around 4.2~GeV. The measurement is compatible with an earlier measurement by Belle, but with a significantly improved precision.

By analyzing 2.93 fb$^{-1}$ data collected at the center-of-mass energy $\sqrt s=3.773$ GeV with the BESIII detector, we measure the absolute branching fraction of the semileptonic decay $D^+\rightarrow\bar K^0 e^{+}\nu_{e}$ to be ${\mathcal B}(D^{+}\rightarrow\bar K^0 e^{+}\nu_{e})=(8.59 \pm 0.14 \pm 0.21)\%$ using $\bar K^0\to K^0_S\to \pi^0\pi^0$, where the first uncertainty is statistical and the second systematic. Our result is consistent with previous measurements within uncertainties.

Using 482~pb$^{-1}$ of $e^+e^-$ collision data collected at a center-of-mass energy of $\sqrt{s} = 4.009$ GeV with the BESIII detector, we measure the branching fractions of the decays $D_s^+\to\mu^+\nu_\mu$ and $D_s^+\to\tau^+\nu_\tau$. By constraining the ratio of decay rates of $D_s^+$ to $\tau^+\nu_\tau$ and to $\mu^+\nu_\mu$ to the Standard Model prediction, the branching fractions are determined to be $\mathcal{B}(D_s^+ \to \mu^+\nu_\mu) = (0.495 \pm 0.067 \pm 0.026)\%$ and $\mathcal{B}(D_s^+ \to \tau^+\nu_\tau) = (4.83 \pm 0.65 \pm 0.26)\%$. Using these branching fractions, we obtain a value for the decay constant $f_{D_s^+}$ of $(241.0 \pm 16.3 \pm 6.5)~\text{MeV}$, where the first error is statistical and the second systematic.

Aims. Most pulsar nulling observations have been conducted at frequencies lower than 1400 MHz. We aim to understand the nulling behaviors of pulsars at relatively high frequencies, and to decipher whether or not nulling is caused by a global change in the pulsar magnetosphere. Methods. We used the Jiamusi 66 m telescope to observe 20 bright pulsars at 2250 MHz with unprecedented lengths of time. We estimated the nulling fractions of these pulsars, and identified the null and emission states of the pulses. We also calculated the nulling degrees and scales of the emission-null pairs to describe the distributions of emission and null lengths. Results. Three pulsars, PSRs J0248+6021, J0543+2329, and J1844+00, are found to null for the first time. The details of null-to-emission and emission-to-null transitions within the pulse window are observed for the first time for PSR J1509+5531, which is a low-probability event. A complete cycle of long nulls with timescales of hours is observed for PSR J1709−1640. For most of these pulsars, the K-S tests of nulling degrees and nulling scales reject the hypothesis that null and emission are caused by random processes at high significance levels. Emission-null sequences of some pulsars exhibit quasi-periodic, low-frequency or featureless modulations, which might be related to different origins. During transitions between emission and null states, pulse intensities have diverse tendencies for variation. Significant correlations are found between respectively nulling fraction, nulling cadence, and nulling scale and the energy loss rate of the pulsars. Combined with the nulling fractions reported in the literature for 146 nulling pulsars, we find that statistically large nulling fractions are more tightly related to pulsar period than to characteristic age or energy-loss rate.

As one of the major components of the interstellar medium, the ionized gas in our Milky Way, especially the low-density diffuse component, has not been extensively observed in the radio band. The Galactic Plane Pulsar Snapshot (GPPS) survey covers the sky area within the Galactic latitude of ±10° around the Galactic plane visible by the Five-hundred-meter Aperture Spherical radio Telescope (FAST), and the spectral line data are simultaneously recorded during the pulsar survey observations. With an integration time of 5 min for each beam, the GPPS survey project provides the most sensitive piggyback spectra for tens of radio recombination lines (RRLs) in the band of 1000–1500 MHz for Hnα, Henα, Cnα, as well as Hnβ and Hnγ. We processed the spectral data of RRLs, and obtained a sensitive averaged Hnα RRL map of a sky area of 88 square degrees in the inner Galaxy of 33° ≼ l ≼ 55° and ∣b∣ ≼ 2°0. The final spectral data of the Hnα RRLs have a spatial resolution of ∼3′, a spectral resolution of 2.2 km s−1, and a typical spectral RMS noise of 0.25 mJy beam−1 or 6.3 mK in main-beam brightness temperature. The FAST GPPS Hnα RRL observations are sensitive down to an emission measure of about 200 cm−6 pc if a 3σ detection limit is required. The new Hnα RRL map shows complex structural features dominated by a number of Hii regions and large extended diffuse ionized gas regions. We detect about 94% of the known Hii regions and confirm 43 WISE Hii regions in the observed sky area. Several large Hii regions or star-forming complexes in the distant outer Galaxy are resolved in the map of Hnα RRLs. Extended RRL features of the diffuse ionized gas are detected. In addition, the GPPS piggyback spectral-line data also provide sensitive detection for other kinds of RRLs, such as the Henα, Cnα, Hnβ, and Hnγ RRLs. The RRL data products of the GPPS survey will be published and updated at http://zmtt.bao.ac.cn/MilkyWayFAST/ .

The vector charmoniumlike state $Y(4220)$ was reported recently in the cross sections of ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{h}_{c}$, $\ensuremath{\omega}{\ensuremath{\chi}}_{c0}$, ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}J/\ensuremath{\psi}$, and ${D}^{0}{D}^{*\ensuremath{-}}{\ensuremath{\pi}}^{+}+\mathrm{c}.\mathrm{c}.$ measured by the BESIII experiment. A combined fit is performed to the cross sections of these four final states to measure the resonant parameters of the $Y(4220)$. We determine a mass $M=(4219.6\ifmmode\pm\else\textpm\fi{}3.3\ifmmode\pm\else\textpm\fi{}5.1)\text{ }\text{ }\mathrm{MeV}/{c}^{2}$ and a total width $\mathrm{\ensuremath{\Gamma}}=(56.0\ifmmode\pm\else\textpm\fi{}3.6\ifmmode\pm\else\textpm\fi{}6.9)\text{ }\text{ }\mathrm{MeV}$ for the $Y(4220)$, where the first uncertainties are statistical and the second ones systematic. We determine the lower limit of its leptonic decay width of around 30 eV, which can be compared with the theoretical expectations of different models. We also estimate its partial decay width to $\ensuremath{\pi}\ensuremath{\pi}J/\ensuremath{\psi}$ in different scenarios. This information is essential for the understanding of the nature of this state.

Based on a sample of $1.31 \times 10^9$ $J/\psi$ events collected with the BESIII detector, an amplitude analysis of the isospin-violating decays $\eta^\prime \rightarrow \pi^+\pi^-\pi^0$ and $\eta^\prime \rightarrow \pi^0\pi^0\pi^0$ is performed. A significant $P$-wave contribution from $\eta^\prime \rightarrow \rho^{\pm} \pi^{\mp}$ is observed for the first time in $\eta^\prime \rightarrow \pi^+\pi^-\pi^0$. The branching fraction is determined to be ${\mathcal B}(\eta^\prime \rightarrow \rho^{\pm}\pi^{\mp})=(7.44\pm0.60\pm1.26\pm1.84)\times 10^{-4}$, 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 $\sigma$ meson component. The branching fractions of the combined $S$-wave components are determined to be ${\mathcal B}(\eta^\prime \rightarrow \pi^+\pi^-\pi^0)_S=(37.63\pm0.77\pm2.22\pm4.48)\times 10^{-4}$ and ${\mathcal B}(\eta^\prime \rightarrow \pi^0\pi^0\pi^0)=(35.22\pm0.82\pm2.54)\times 10^{-4}$, respectively. The latter one is consistent with previous BESIII measurements.

Neutral hydrogen (HI) is the fundamental component of the interstellar medium. The Galactic Plane Pulsar Snapshot (GPPS) survey is designed for hunting pulsars by using the Five-hundred-meter Aperture Spherical radio Telescope (FAST) from the visible Galactic plane within $|b| \leq 10^{\circ}$. The survey observations are conducted with the L-band 19-beam receiver in the frequency range of 1.0 $-$ 1.5 GHz, and each pointing has an integration time of 5 minutes. The piggyback spectral data simultaneously recorded during the FAST GPPS survey are great resources for studies on the Galactic HI distribution and ionized gas. We process the piggyback HI data of the FAST GPPS survey in the region of $33^{\circ} \leq l \leq 55^{\circ}$ and $|b| \leq 2^{\circ}$. The rms of the data cube is found to be approximately 40 mK at a velocity resolution of $0.1$ km s$^{-1}$, placing it the most sensitive observations of the Galactic HI by far. The high velocity resolution and high sensitivity of the FAST GPPS HI data enable us to detect weak exquisite HI structures in the interstellar medium. HI absorption line with great details can be obtained against bright continuum sources. The FAST GPPS survey piggyback HI data cube will be released and updated on the web: http://zmtt.bao.ac.cn/MilkyWayFAST/.

A5° × 7° sky area containing two large radio structures of G203.1+6.6 and G206.7+5.9 with a size of about 2°.5 and 3°.5 respectively is scanned by using the L-band 19-beam receiver of the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The FAST L-band receiver covers a frequency range of 1.0–1.5 GHz. Commissioning of the receiving system, including the measurements of the half-power beam width, gain, and main-beam efficiency is made by observing the calibrators. The multi-channel spectroscopy backend mounted to the receiver allows an in-band spectral-index determination. The brightness-temperature spectral indices of both objects are measured to be β ∼ −2.6 to −2.7. Polarized emission is detected from the archival Effelsberg λ11 cm data for all the shell structures of G203.1 +6.6 and G206.7+5.9. These results clearly indicate a non-thermal synchrotron emitting nature, confirming that G203.1+6.6 and G206.7+5.9 are large shell-type supernova remnants (SNRs). Based on morphological correlation between the radio continuum emission of G206.7+5.9 and the Hi structures, the kinematic distance to this new SNR is estimated to be about 440 pc, placing it in the Local Arm.

Quasi-2D Coulomb systems are of fundamental importance and have attracted much attention in many areas nowadays. Their reduced symmetry gives rise to interesting collective behaviors, but also brings great challenges for particle-based simulations. Here, we propose a novel algorithm framework to address the $\mathcal O(N^2)$ simulation complexity associated with the long-range nature of Coulomb interactions. First, we introduce an efficient Sum-of-Exponentials (SOE) approximation for the long-range kernel associated with Ewald splitting, achieving uniform convergence in terms of inter-particle distance, which reduces the complexity to $\mathcal{O}(N^{7/5})$. We then introduce a random batch sampling method in the periodic dimensions, the stochastic approximation is proven to be both unbiased and with reduced variance via a tailored importance sampling strategy, further reducing the computational cost to $\mathcal{O}(N)$. The performance of our algorithm is demonstrated via varies numerical examples. Notably, it achieves a speedup of $2\sim 3$ orders of magnitude comparing with Ewald2D method, enabling molecular dynamics (MD) simulations with up to $10^6$ particles on a single core. The present approach is therefore well-suited for large-scale particle-based simulations of Coulomb systems under confinement, making it possible to investigate the role of Coulomb interaction in many practical situations.

This study employs grand canonical Monte Carlo (GCMC) simulations to investigate the impact of functional group modifications (CH3 , OH, NH2 , and OLi) on the adsorption performance of CH4 /N2 on Ni-MOF-74. The results revealed that functional group modifications significantly increased the adsorption capacity of Ni-MOF-74 for both CH4 and N2 . The packed methyl groups in CH3 -Ni-MOF-74 create an environment conducive to CH4 , leading to the highest CH4 adsorption capacity. The electrostatic potential distribution indicates that the strong electron-donating effect introduced by the alkali metal Li results in the highest electrostatic potential gradient in Li-O-Ni-MOF-74, leading to the strongest adsorption of N2 , this is unfavorable for CH4 /N2 separation. At 1500 kPa the selectivity order of adsorbents for mixed gases was as follows: CH3 -Ni-MOF-74 > NH2 -Ni-MOF-74 > OH-Ni-MOF-74 > Ni-MOF-74 > Li-O-Ni-MOF-74. This study highlights that CH3 -Ni-MOF-74 possesses optimal CH4 selectivity and adsorption performance. Given the current lack of research on functionalized MOF-74 for the separation of CH4 and N2 , the findings of this study will serve as a theoretical guide and provide references for the applications of CH4 adsorption and CH4 /N2 separation.

Large-scale radio continuum surveys have good potential for discovering new Galactic supernova remnants (SNRs). Surveys of the Galactic plane are often limited in the Galactic latitude of |b| ~ 5 degree. SNRs at high latitudes, such as the Cygnus Loop or CTA~1, cannot be detected by surveys in such limited latitudes. Using the available Urumqi 6 cm Galactic plane survey data, together with the maps from the extended ongoing 6 cm medium latitude survey, we wish to discover new SNRs in a large sky area. We searched for shell-like structures and calculated radio spectra using the Urumqi 6 cm, Effelsberg 11 cm, and 21 cm survey data. Radio polarized emission and evidence in other wavelengths are also examined for the characteristics of SNRs. We discover an enclosed oval-shaped object G150.3+4.5 in the 6 cm survey map. It is about 2.5 degree wide and 3 degree high. Parts of the shell structures can be identified well in the 11 cm, 21 cm, and 73.5 cm observations. The Effelsberg 21 cm total intensity image resembles most of the structures of G150.3+4.5 seen at 6 cm, but the loop is not closed in the northwest. High resolution images at 21 cm and 73.5 cm from the Canadian Galactic Plane Survey confirm the extended emission from the eastern and western shells of G150.3+4.5. We calculated the radio continuum spectral indices of the eastern and western shells, which are $\beta \sim -2.4$ and $\beta \sim -2.7$ between 6 cm and 21 cm, respectively. The shell-like structures and their non-thermal nature strongly suggest that G150.3+4.5 is a shell-type SNR. For other objects in the field of view, G151.4+3.0 and G151.2+2.6, we confirm that the shell-like structure G151.4+3.0 very likely has a SNR origin, while the circular-shaped G151.2+2.6 is an HII region with a flat radio spectrum, associated with optical filamentary structure, H$\alpha$, and infrared emission.

In response to the limitations of the DQN algorithm in adaptability, which result in a low success rate in ship path planning, this paper introduces an improved algorithm based on Deep Q-learning (DQN) to enhance path planning. The proposed algorithm aims to plan a reasonable and cost-effective route to the destination based on all historical track, regardless of the current location of ship within the environment. Firstly, the k-means clustering algorithm is employed to cluster the historical ship locations. The value of k is progressively increased to include more locations, allowing the model to interact with the environment of increasing complexity. This approach enhances the generalization capability of the model by enabling it to autonomously devise a route from any starting point to the destination port. On the other hand, for the ship path problem, the DQN algorithm is enhanced through the optimization of the reward function. This improvement targets the challenges of convergence difficulty and low learning efficiency, which greatly improves the rate of convergence for the model. Finally, the effectiveness of the method is verified by comparing it experimentally in terms of the effectiveness of path planning and model convergence trend. The results demonstrate that the improved DQN algorithm achieves a convergence speed improvement of over 25%. Additionally, with the same training time, the success rate of path planning from any position to destination within the environment is enhanced by 44%. It has better effect on the path planning of ships.

Electronic skin(e-skin) is an emerging type of wearable sensor in order to translate external stimuli into different output signals. Electronic skin is very important in many fields, including Artificial intelligence, smart medicine, and virtual reality. The electronic skin is made of a composite material called QCT and various transistors and sensors. Therefore, electronic skin can convert various biological signals such as temperature, pain, pressure, etc. into electrical signals. In addition, the electronic skin has the characteristics of being thin, soft, and flexible. This article will first introduce the application of electronic skin in artificial intelligence, electronic skin can make artificial intelligence better sense and adapt to changes in the environment. The second is the role of smart medicine, the most widely used is the use of prosthetics. Finally, there is the role of virtual reality, which allows users to have a more realistic experience through the use of electronic skin. The findings presented in this paper hold significant value for advancing research and facilitating the practical application of electronic skin technology.

Context. Supernova remnants (SNRs) were often discovered in radio surveys of the Galactic plane. Because of the surface-brightness limit of previous surveys, more faint or confused SNRs await discovery. The Sino-German λ6 cm Galactic plane survey is a sensitive survey with the potential to detect new low-surface-brightness SNRs.

Using a sample of 1.31×109 J/ψ events collected with the BESIII detector at the BEPCII collider, the decays J/ψ→ϕπ+π−π0 and J/ψ→ϕπ0π0π0 are investigated. The isospin-violating decay J/ψ→ϕπ0f0(980) with f0(980)→ππ is observed for the first time. The width of the f0(980) obtained from the dipion mass spectrum is found to be much smaller than the world average value. In the π0f0(980) mass spectrum, there is evidence of f1(1285) production. By studying the decay J/ψ→ϕη′, the branching fractions of η′→π+π−π0 and η′→π0π0π0, as well as their ratio, are also measured.Received 23 May 2015DOI:https://doi.org/10.1103/PhysRevD.92.012007© 2015 American Physical Society

A study group was formed in Beijing in September 2013 to investigate the feasibility of a high energy Circular Electron Positron Collider (CEPC) as a Higgs and/or Z factory, and a subsequent Super proton-proton Collider (SPPC). A provisional organization structure and a management team, consisted mostly of Chinese physicists, were established to guide the initial study [1]. The group aims at establishing an international collaboration on CEPC-SPPC after sufficient progress has been made in China or it has been given government funding for RD Volume 2 describes the CEPC accelerator design and SPPC consideration, and the associated civil engineering [2]. The contents presented are preliminary and are predominately focused on the CEPC. Formal CDR and TDR work will follow.

Based on 2.93 fb^{-1} e^{+}e^{-} collision data taken at center-of-mass energy of 3.773 GeV by the BESIII detector, we report searches for the singly Cabibbo-suppressed decays D^{+}→ωπ^{+} and D^{0}→ωπ^{0}. A double tag technique is used to measure the absolute branching fractions B(D^{+}→ωπ^{+})=(2.79±0.57±0.16)×10^{-4} and B(D^{0}→ωπ^{0})=(1.17±0.34±0.07)×10^{-4}, with statistical significances of 5.5σ and 4.1σ, where the first and second uncertainties are statistical and systematic, respectively.

Replacing natural aggregate (NA) with recycled aggregate (RA) has contributed to the trend of sustainable development in civil construction. With this background, improvements in the mechanical properties of recycled aggregate concrete (RAC) and the scientific design of the mixture ratio are attracting more concern in recent years. This paper is a review of the recent research, including the following aspects: the mixture design of RAC; the improved mechanical properties of recycled concrete with steel fibers; and the performance of the main components. In addition, the primary composition materials, properties, and calculation methods of the mixture ratio of RAC are summarized. The mechanical properties, durability and microscopic analysis of RAC are also discussed. The accurate calculation of mixture proportion can significantly facilitate the work of preparing a test mix of RAC. Through the mixture-ratio optimization and physical and chemical strengthening of RA, the mechanical properties of RAC can be improved to promote the wider application of this eco-friendly material.

Abstract We present total-intensity and polarized-intensity images of the Cygnus Loop supernova remnant (SNR) observed by the Five-hundred-meter Aperture Spherical radio Telescope. The high angular-resolution and high-sensitivity images enable us to thoroughly compare the properties of the northern part with the southern part of the SNR. The central filament in the northern part and the southern part have a similar foreground rotation measure, meaning their distances are likely similar. The polarization analysis indicates that the random magnetic field is larger than the regular field in the northern part, but negligible in the southern part. The total-intensity image is decomposed into components of various angular scales, and the brightness-temperature spectral index of the shell structures in the northern part is similar to that in the southern part in the component images. All the evidence suggests that the northern and southern parts of the Cygnus Loop are situated and thus evolved in different environments of interstellar medium, while belonging to the same SNR.

Using $2.92\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of electron-positron annihilation data collected at $\sqrt{s}=3.773\text{ }\text{ }\mathrm{GeV}$ with the BESIII detector, we report the results of a search for the flavor-changing neutral current process ${D}^{0}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}$ using a double-tag technique. We find no signal and set an upper limit at 90% confidence level for the branching fraction of $\mathcal{B}({D}^{0}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma})&lt;3.8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$. We also investigate ${D}^{0}$-meson decay into two neutral pions, obtaining a branching fraction of $\mathcal{B}({D}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0})=(8.24\ifmmode\pm\else\textpm\fi{}0.21(\text{stat})\ifmmode\pm\else\textpm\fi{}0.30(\text{syst}))\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$, the most precise measurement to date and consistent with the current world average.

Using the data sets taken at center-of-mass energies above 4 GeV by the BESIII detector at the BEPCII storage ring, we search for the reaction e+e- -> gamma_ISR X(3872) -> gamma_ISR pi+pi-J/psi via the Initial State Radiation technique. The production of a resonance with quantum numbers J^PC = 1^++ such as the X(3872) via single photon e+e- annihilation is forbidden, but is allowed by a next-to-leading order box diagram. We do not observe a significant signal of X(3872), and therefore give an upper limit for the electronic width times the branching fraction Gamma_ee^X(3872)Br(X(3872) -> pi+pi-J\psi) < 0.13 eV at the 90% confidence level. This measurement improves upon existing limits by a factor of 46. Using the same final state, we also measure the electronic width of the psi(3686) to be Gamma_ee^psi(3686) = 2231 +- 18 +- 99 eV.

Context. Radio continuum observations detect non-thermal synchrotron and thermal bremsstrahlung radiation. Separation of the two different emission components is crucial for studying the properties of the Galactic interstellar medium. The Cygnus X region is one of the most complex areas in the radio sky, which contains a number of massive stars and H ii regions on the diffuse thermal and non-thermal background. More supernova remnants (SNRs) are expected to be discovered.

We search for a light Higgs boson $A^0$ in the fully reconstructed decay chain of $J/\psi \rightarrow \gamma A^0$, $A^0 \rightarrow \mu^+\mu^-$ using $(225.0\pm2.8)\times10^6$ $J/\psi$ events collected by the BESIII experiment. The $A^0$ is a hypothetical CP-odd light Higgs boson predicted by many extensions of the Standard Model including two spin-0 doublets plus an extra singlet. We find no evidence for $A^0$ production and set $90\%$ confidence-level upper limits on the product branching fraction $\mathcal{B}(J/\psi \rightarrow \gamma A^0) \times \mathcal{B}(A^0 \rightarrow \mu^+\mu^-)$ in the range of $(2.8-495.3)\times 10^{-8}$ for $0.212 \le m_{A^0} \le 3.0$ GeV/c$^2$. The new limits are $5$ times below our previous results, and the nature of the $A^0$ is constrained to be mostly singlet.

In recent years, serious fire and explosion accident in petrochemical storage tanks have taken place frequently. Therefore, increasing the firefighting force in petrochemical parks is particularly important. The ambition of the paper is mainly studying the supply intensity of Aqueous Film Forming Foam (AFFF) extinguishing agent. Fire extinguishing agent demand calculation method that can be capable of matching fire scale is established by carrying out series of fire extinguishing experiments. 6% AFFF is chosen to carry out three groups of experiments respectively: fire extinguishing agent fluidity determination, series groups of small size simulation oil pool fire and 177 square meters of large oil pool fire extinguishing experiment. The situation of fire extinguishing on fuel surface of AFFF can be explored through experimental means under cold and hot conditions. The data obtained from experiments prove a higher conformity between covering process and covering model under the cold condition. The model can predict the cold coverage of AFFF effectively. After unifying the supply flow from each experiment, the statistics can be fitted and come to the minimum supply intensity algorithm of AFFF against the target storage tank specifications. The algorithm is used to estimate the minimum supply intensity when extinguishing full liquid surface fire. This model also can be used as reference for petrochemical fire protection.

Context . Large-scale radio continuum surveys provide data to get insights into the physical properties of radio sources. H II regions are prominent radio sources produced by thermal emission of ionised gas around young massive stars. Aims . We identify and analyse H II regions in the Sino-German λ 6 cm polarisation survey of the Galactic plane. Methods . Objects with flat radio continuum spectra together with infrared and/or H α emission were identified as H II regions. For H II regions with small apparent sizes, we cross-matched the λ 6 cm small-diameter source catalogue with the radio H II region catalogue compiled by Paladini and the infrared H II region catalogue based on the WISE data. Effelsberg λ 21 cm and λ 11 cm continuum survey data were used to determine source spectra. High angular resolution data from the Canadian Galactic Plane Survey and the NRAO VLA Sky Survey were used to solve the confusion when low angular resolution observations were not sufficient. Extended H II regions were identified by eye by overlaying the Paladini and the WISE H II regions onto the λ 6 cm survey images for coincidences. The TT-plot method was employed for spectral index verification. Results . A total of 401 H II regions were identified and their flux densities were determined with the Sino-German λ 6 cm survey data. In the surveyed area, 76 pairs of sources are found to be duplicated in the Paladini H II region catalogue, mainly due to the non-distinction of previous observations with different angular resolutions and 78 objects in their catalogue are misclassified as H II regions, being actually planetary nebulae, supernova remnants, or extragalactic sources that have steep spectra. More than 30 H II regions and H II region candidates from our λ 6 cm survey data, especially extended ones, do not have counterparts in the WISE H II region catalogue, of which 9 are identified for the first time. Our results imply that some more Galactic H II regions still await to be discovered and the combination of multi-domain observations is important for H II region identification. Based on the newly derived radio continuum spectra and the evidence of infrared emission, the previously identified SNRs G11.1−1.0, G20.4+0.1 and G16.4−0.5 are believed to be H II regions.

Abstract We report on the continuum and polarization observations of the Cygnus Loop supernova remnant (SNR) conducted by the Five-hundred-meter Aperture Spherical radio Telescope (FAST). FAST observations provide high angular resolution and high sensitivity images of the SNR, which will help to disentangle its nature. We obtained Stokes I , Q and U maps over the frequency range of 1.03 – 1.46 GHz split into channels of 7.63 kHz. The original angular resolution is in the range of <?CDATA $\sim {3}^{\prime}-\sim {3}^{\prime}.8$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>∼</mml:mo> <mml:msup> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>′</mml:mo> </mml:mrow> </mml:msup> <mml:mo>−</mml:mo> <mml:mo>∼</mml:mo> <mml:msup> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>′</mml:mo> </mml:mrow> </mml:msup> <mml:mn>.8</mml:mn> </mml:math> , and we combined all the data at a common resolution of <?CDATA ${4}^{\prime}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow> <mml:mn>4</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>′</mml:mo> </mml:mrow> </mml:msup> </mml:math> . The temperature scale of the total intensity and the spectral index from the in-band temperature-temperature plot are consistent with previous observations, which validates the data calibration and map-making procedures. The rms sensitivity for the band-averaged total-intensity map is about 20 mK in brightness temperature, which is at the level of confusion limit. For the first time, we apply rotation measure (RM) synthesis to the Cygnus Loop to obtain the polarization intensity and RM maps. The rms sensitivity for polarization is about 5 mK, far below the total-intensity confusion limit. We also obtained RMs of eight extragalactic sources, and demonstrate that the wide-band frequency coverage helps to overcome the ambiguity of RM determinations.

Abstract Double radio lobes are generally believed to be produced by active nuclei of elliptical galaxies. However, several double-lobed radio sources have been solidly found to be associated with spiral galaxies. By cross-matching ∼9 × 10 5 spiral galaxies selected from the Sloan Digital Sky Survey DR8 data with the full 1.4 GHz radio source catalogs of NRAO VLA Sky Survey and Faint Images of the Radio Sky at Twenty-centimeters, we identify three new spiral galaxies: J0326−0623, J1110+0321 and J1134+3046 that produce double radio lobes, and five double-lobed spirals previously known. By combining the newly discovered and all the other known cases in literature, we confirm the relation that more massive spiral galaxies could produce more powerful radio lobes. We find that most of these spiral galaxies are located in a galaxy group or a poor cluster, in which the environment is denser than in the field, and about half of them are the central brightest galaxies in their parent system. We therefore suggest that the environment is one of the key factors for a spiral to produce double radio lobes.

The pulsar B0458+46 was previously believed to have a distance of about 1.3$~$kpc and to be associated with a nearby supernova remnant, SNR HB9 (G160.9+2.6). We observe the neutral hydrogen (HI) absorption spectrum of PSR B0458+46 by using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), and detect two absorption lines at radial velocities of $V_{\rm LSR} = {-7.7}~{\rm km~s}^{-1}$ and $-28.1~{\rm km~s^{-1}}$. Based on the Galactic rotation curve with a modification factor correcting for the systematic stream in the anticenter region, we derive the kinematic distance of the farther absorption cloud, which is found to be located $2.7^{+0.9}_{-0.8}$ kpc away, just beyond the Perseus Arm. We also obtain a direct distance estimation of the absorption clouds, being $2.3_{-0.7}^{+1.1}$ kpc, based on a comparison of their velocity with the HI emission in the Perseus and Outer Arms that was well-defined by recently measured parallax tracers. As a result, we conclude that PSR B0458+46 should be located beyond the Perseus Arm, with a lower limit distance of 2.7 kpc, and therefore not associated with SNR HB9. The doubled distance indicates a deficiency of thermal electrons in the immediate outer Galaxy, with much less density than current models predict. Additionally, we detect a new high-velocity HI cloud in the direction of this pulsar.

We present the first search for the rare decay of $\eta^\prime$ into $K^{\pm}\pi^{\mp}$ in $J/\psi\to\phi\eta^{\prime}$, using a sample of $1.3\times10^{9}$ $J/\psi$ events collected with the BESIII detector. No significant signal is observed, and the upper limit at the 90\% confidence level for the ratio $\frac{{\cal B}(\eta^{\prime}\to K^{\pm}\pi^{\mp})}{{\cal B}(\eta^{\prime}\to\gamma\pi^{+}\pi^{-})}$ is determined to be $1.3\times10^{-4}$. In addition, we report the measurement of the branching fraction of $J/\psi\to\phi\eta^{\prime}$ to be $(5.10\pm0.03(\text{stat.})\pm0.32(\text{syst.}))\times10^{-4}$, which agrees with previous results from BESII.

Using data samples collected at center of mass energies of $\sqrt{s}$ = 4.009, 4.226, 4.257, 4.358, 4.416 and 4.599 GeV with the BESIII detector operating at the BEPCII storage ring, we search for the isospin violating decay $Y(4260)\rightarrow J/\psi \eta \pi^{0}$. No signal is observed, and upper limits on the cross section $\sigma(e^{+}e^{-}\rightarrow J/\psi \eta \pi^{0})$ at the 90\% confidence level are determined to be 3.6, 1.7, 2.4, 1.4, 0.9 and 1.9 pb, respectively.

Context. Pulsars scintillate. Dynamic spectra show brightness variation of pulsars in the time and frequency domain. Secondary spectra demonstrate the distribution of fluctuation power in the dynamic spectra. Aims. Dynamic spectra strongly depend on observational frequencies, but were often observed at frequencies lower than 1.5 GHz. Scintillation observations at higher frequencies help to constrain the turbulence feature of the interstellar medium over a wide frequency range and can detect the scintillations of more distant pulsars. Methods. Ten pulsars were observed at 2250 MHz (S-band) with the Jiamusi 66 m telescope to study their scintillations. Their dynamic spectra were first obtained, from which the decorrelation bandwidths and time scales of diffractive scintillation were then derived by autocorrelation. Secondary spectra were calculated by forming the Fourier power spectra of the dynamic spectra. Results. Most of the newly obtained dynamic spectra are at the highest frequency or have the longest time span of any published data for these pulsars. For PSRs B0540+23, B2324+60 and B2351+61, these were the first dynamic spectra ever reported. The frequencydependence of scintillation parameters indicates that the intervening medium can rarely be ideally turbulent with a Kolmogorov spectrum. The thin screen model worked well at S-band for the scintillation of PSR B1933+16. Parabolic arcs were detected in the secondary spectra of three pulsars, PSRs B0355+54, B0540+23 and B2154+40, all of which were asymmetrically distributed. The inverted arclets of PSR B0355+54 were seen to evolve along the main parabola within a continuous observing session of 12 hours, from which the angular velocity of the pulsar was estimated that was consistent with the measurement by very long baseline interferometry (VLBI).

By analyzing a data set of 2.92 fb$^{-1}$ of $e^+e^-$ collision data taken at $\sqrt s= 3.773~\rm GeV$ and 106.41$\times 10^{6}$ $\psi(3686)$ decays taken at $\sqrt s= 3.686~\rm GeV$ with the BESIII detector at the BEPCII collider, we measure the branching fraction and the partial decay width for $\psi(3770)\to\gamma\chi_{c0}$ to be ${\mathcal B}(\psi(3770)\to\gamma\chi_{c0})=(6.88\pm0.28\pm0.67)\times 10^{-3}$ and $\Gamma[\psi(3770)\to\gamma\chi_{c0}]=(187\pm8\pm19)~\rm keV$, respectively. These are the most precise measurements to date.

Using a data set of 2.93 fb−1 taken at a center-of-mass energy of s=3.773GeV with the BESIII detector at the BEPCII collider, we measure the process e+e−→J/ψγ→μ+μ−γ and determine the product of the branching fraction and the electronic width Bμμ⋅Γee=(333.4±2.5stat±4.4sys)eV. Using the earlier-published BESIII result for Bμμ=(5.973±0.007stat±0.037sys)%, we derive the J/ψ electronic width Γee=(5.58±0.05stat±0.08sys)keV.

Linearly polarized Galactic synchrotron emission provides valuable information about the properties of the Galactic magnetic field and the interstellar magneto-ionic medium, when Faraday rotation along the line of sight is properly taken into account. We aim to survey the Galactic plane at 6 cm including linear polarization. At such a short wavelength Faraday rotation effects are in general small and the Galactic magnetic field properties can be probed to larger distances than at long wavelengths. The Urumqi 25-m telescope is used for a sensitive 6 cm survey in total and polarized intensities. WMAP K-band (22.8 GHz) polarization data are used to restore the absolute zero-level of the Urumqi U and Q maps by extrapolation. Total intensity and polarization maps are presented for a Galactic plane region of 129 degree < l < 230 degree and |b| < 5 degree in the anti-centre with an angular resolution of 9'5 and an average sensitivity of 0.6 mK and 0.4 mK Tb in total and polarized intensity, respectively. We briefly discuss the properties of some extended Faraday Screens detected in the 6 cm polarization maps. The Sino-German 6 cm polarization survey provides new information about the properties of the magnetic ISM. The survey also adds valuable information for discrete Galactic objects and is in particular suited to detect extended Faraday Screens with large rotation measures hosting strong regular magnetic fields.

ABSTRACT Sensitive radio continuum surveys of the Galactic plane are ideal for discovering new supernova remnants (SNRs). From the Sino-German λ6-cm polarization survey of the Galactic plane, an extended shell-like structure has been found at ℓ = 21${^{\circ}_{.}}$8, b = −3${^{\circ}_{.}}$0, which has a size of about 1°. New observations were made with the Effelsberg 100-m radio telescope at λ11 cm to estimate the source spectrum, together with Urumqi λ6-cm and Effelsberg λ21-cm data. The spectral index of G21.8−3.0 was found to be α = −0.72 ± 0.16. Polarized emission was mostly detected in the eastern half of G21.8−3.0 at both λ6 and λ11 cm. These properties, together with the Hα filament along its northern periphery and the lack of infrared emission, indicate that the emission is non-thermal, as is usual in shell-type SNRs.

We study Ds+ decays to final states involving the η′ with a 482 pb−1 data sample collected at s=4.009 GeV with the BESIII detector at the BEPCII collider. We measure the branching fractions B(Ds+→η′X)=(8.8±1.8±0.5)% and B(Ds+→η′ρ+)=(5.8±1.4±0.4)% where the first uncertainty is statistical and the second is systematic. In addition, we estimate an upper limit on the non-resonant branching ratio B(Ds+→η′π+π0)<5.1% at the 90% confidence level. Our results are consistent with CLEO's recent measurements and help to resolve the disagreement between the theoretical prediction and CLEO's previous measurement of B(Ds+→η′ρ+).

We report a measurement of the branching fraction for $\ensuremath{\psi}(3770)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{c1}$ and search for the transition $\ensuremath{\psi}(3770)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{c2}$ based on $2.92\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of ${e}^{+}{e}^{\ensuremath{-}}$ data accumulated at $\sqrt{s}=3.773\text{ }\text{ }\mathrm{GeV}$ with the BESIII detector at the BEPCII collider. We measure $\mathcal{B}(\ensuremath{\psi}(3770)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{c1})=(2.48\ifmmode\pm\else\textpm\fi{}0.15\ifmmode\pm\else\textpm\fi{}0.23)\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}3}$, which is the most precise measurement to date. The upper limit on the branching fraction of $\ensuremath{\psi}(3770)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{c2}$ at a 90% confidence level is $\mathcal{B}(\ensuremath{\psi}(3770)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{c2})&lt;0.64\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}3}$. The corresponding partial widths are $\mathrm{\ensuremath{\Gamma}}(\ensuremath{\psi}(3770)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{c1})=(67.5\ifmmode\pm\else\textpm\fi{}4.1\ifmmode\pm\else\textpm\fi{}6.7)\text{ }\mathrm{keV}$ and $\mathrm{\ensuremath{\Gamma}}(\ensuremath{\psi}(3770)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{c2})&lt;17.4\text{ }\mathrm{keV}$.

Aims. We study the spectral and polarization properties of supernova remnants (SNRs) using our λ 6 cm survey data. Methods. We analyse data from observations taken as part of the Sino-German λ 6 cm polarization survey of the Galactic plane. By using the integrated flux densities at λ 6 cm together with measurements at other wavelengths from the literature, we derive the global spectra of 50 SNRs. In addition, from the observations at λ 6 cm we obtain the polarization images of 24 SNRs. Results. We derive integrated flux densities at λ 6 cm for 51 small SNRs with angular sizes smaller than 1°. We are able to derive global radio spectral indices in all the cases except for Cas A. For the SNRs G15.1−1.6, G16.2−2.7, G16.4−0.5, G17.4−2.3, G17.8−2.6, G20.4+0.1, G36.6+2.6, G43.9+1.6, G53.6−2.2, G55.7+3.4, G59.8+1.2, G68.6−1.2, and G113.0+0.2, the spectra have been significantly improved. From our analysis, we argue that the object G16.8−1.1 is probably an H ii region instead of a SNR. Cas A shows a secular decrease in total intensity, and we measure a flux density of 688  ±  35 Jy at λ 6 cm between 2004 and 2008. We detect polarized emission from 25 SNRs. For G16.2−2.7, G69.7+1.0, G84.2−0.8, and G85.9−0.6, the polarized emission is detected for the first time confirming that they are SNRs.Conclusions. High-frequency observations of SNRs are difficult but essential to determine their spectra and measure their polarization in particular towards the inner Galaxy, where Faraday effects are important.

We have finished the 6cm polarization survey of the Galactic plane using the Urumqi 25m radio telescope. It covers 10deg<l<230deg in Galactic longitude and |b| <5deg in Galactic latitude. The new polarization maps not only reveal new properties of the diffuse magnetized interstellar medium, but also are very useful for studying individual objects such as Hii regions, which may act as Faraday screens with strong regular magnetic fields inside, and supernova remnants for their polarization properties and spectra. The high sensitivity of the survey enables us to discover two new SNRs G178.2-4.2 and G25.3-2.1 and a number of Hii regions.

ABSTRACT Many of the Spitzer infrared bubbles identified by the Milky Way Project (MWP) are suggested to be $\rm{H \small {II}} $ regions in nature. More than 70 per cent of the ∼5000 known bubbles do not have radio recombination line (RRL) observations, hence have not been confirmed as $\rm{H \small {II}} $ regions. A systematic RRL survey should be helpful to identify the nature of the bubbles. With the Shanghai TianMa 65-m radio telescope, we searched for RRLs towards 216 selected Spitzer bubbles by simultaneously observing 19 RRLs in the C band (4–8 GHz). RRLs are detected in the directions of 75 of the 216 targets. 31 of the 75 RRL sources are classified as new detections, which are possibly from new $\rm{H \small {II}} $ regions or diffuse warm ionized medium; 36 of them are probably from the outskirts of nearby bright $\rm{H \small {II}} $ regions, rather than bubble-encircled ionized gas; and the detected RRLs towards 8 bubbles are identified from known $\rm{H \small {II}} $ regions. For 58 of the 75 RRL sources, we obtained their distances after resolving the kinematic distance ambiguity by combining the results of the H2CO absorption method, the $\rm{H \small {I}} $ emission/absorption method, and the $\rm{H \small {I}} $ self-absorption method. The low detection rate of new $\rm{H \small {II}} $ regions implies that a number of MWP bubbles in the DR1 catalogue are too faint if they are $\rm{H \small {II}} $ regions.

ABSTRACT Magnetic field could play a role in the formation and early evolution of non-spherical planetary nebulae (PNe). The predominant source of information of the magnetic fields in PNe is the polarization observations of maser emission. To date, distinct and/or possible Zeeman pairs have only been reported towards four PNe by measuring the OH ground-state transitions at 1.6–1.7 GHz. With the C-band (4–8 GHz) receiving system of the Shanghai TianMa 65-m radio telescope, we aim to search for possible Zeeman pairs of the PNe towards which the OH excited-state 6.035 GHz maser lines have been detected. For the young PN K 3-35, a new emission component near VLSR = 20.5 km s−1, which is currently the strongest (Ipeak ∼ 0.3 Jy) among the four components towards K 3-35 is detected. A clear S-shaped feature corresponding to this new emission component is observed in the Stokes V spectrum. Frequency shifts are seen between the fitted left-hand circular polarization and right-hand circular polarization emission peaks for the two emission components near VLSR = 19.7 and 20.5 km s−1. If the S-shaped profile and the frequency shifts are the results of Zeeman-splitting, the line-of-sight magnetic field strengths of +2.9 ± 0.6 and +4.5 ± 0.4 mG can be inferred for these two emission components, respectively.

Using a data sample of 1.31×109 J/ψ events accumulated with the BESIII detector, the decay J/ψ→pp¯ϕ is studied via two decay modes, ϕ→KS0KL0 and ϕ→K+K-. The branching fraction of J/ψ→pp¯ϕ is measured to be B(J/ψ→pp¯ϕ)=[5.23±0.06(stat)±0.33(syst)]×10-5, which agrees well with a previously published measurement, but with a significantly improved precision. No evident enhancement near the pp¯ mass threshold, denoted as X(pp¯), is observed, and the upper limit on the branching fraction of J/ψ→X(pp¯)ϕ→pp¯ϕ is determined to be B(J/ψ→X(pp¯)ϕ→pp¯ϕ)<2.1×10-7 at the 90% confidence level.

The cross-sections of [Formula: see text] and [Formula: see text] were measured by the BESIII experiment. In both cross-section distributions, there are structures at a mass of about [Formula: see text]. A combined fit is performed to the two cross-section distributions, assuming the structures are due to the same vector resonant state, the [Formula: see text]. The parameters of the [Formula: see text] are determined using two fit methods. The ratios [Formula: see text] are obtained, which may help in the understanding of the nature of this structure. Although a similar work was done previously, all the multiple solutions in our fits are taken into account and our conclusions are more precise and complete.

Context. Supernova remnants (SNRs) were often discovered in radio surveys of the Galactic plane. Because of the surface-brightness limit of previous surveys, more faint or confused SNRs await discovery. The Sino-German λ 6 cm Galactic plane survey is a sensitive survey with the potential to detect new low-surface-brightness SNRs.Aims. We aim to identify new SNRs from the λ 6 cm survey map of the Galactic plane.Methods. We searched for new shell-like objects in the λ 6 cm survey maps and studied their radio emission, polarization, and spectra using the λ 6 cm maps together with the λ 11 cm and λ 21 cm Effelsberg observations. Extended polarized objects with non-thermal spectra can be identified as SNRs.Results. We have discovered two new, large, faint SNRs, G178.2−4.2 and G25.1−2.3, both of which show shell structure. G178.2−4.2 has a size of 72′ × 62′ with strongly polarized emission being detected along its northern shell. The spectrum of G178.2−4.2 is non-thermal, with an integrated spectral index of α  =  −0.48 ± 0.13. Its surface brightness is Σ1   GHz  = 7.2 × 10-23    Wm-2    Hz-1    sr-1 , which makes G178.2−4.2 the second faintest known Galactic SNR. G25.1−2.3 is revealed by its strong southern shell, which has a size of 80′ × 30′. It has a non-thermal radio spectrum with a spectral index of α  =  −0.49 ± 0.13. Conclusions. Two new large shell-type SNRs have been detected at λ 6 cm in an area of 2200 deg2 along the Galactic plane. This demonstrates that more large and faint SNRs exist, but are very difficult to detect.

Traditional robots are mainly rigid structures. They are complex in structure but limited in flexibility, and have poor security and adaptability. At that time, many bio-inspired robots were created to overcome the traditional robotic challenges. Creatures gave us the inspiration to use a soft body to complete task, and then soft robotics were invented. This paper evaluated the future difficulties faced by this area, and listed the deficiencies that still need to be improved for soft robots that should be overcome in future projects as well. First of all, the first difficulty is that most soft robots rely on software drivers to complete tasks, and because of this, the driving functions of soft robots cannot be perfectly performed, and the action tasks are not diverse. Secondly, if the action moving is over flexible, it will be hard to control. The precision for missions cannot be satisfied. Thirdly, the choice of drivers type becomes another problem. For example, the memory alloy drive has the advantages of large driving force, controllable stiffness, good elasticity, etc., but it also has disadvantages such as easy aging and slow response speed. Although the pneumatic drive has a fast response rate, there is a risk that the fluid may leak, and the environment cannot be guaranteed to be airtight. Obviously, there is no ideal solution to work out actuation difficulties.

The elements in the hyperoctahedral group $\mathfrak{B}_n$ can be treated as signed permutations with the natural order $\cdots<-2<-1<0<1<2<\cdots$, or as colored permutations with the $r$-order $-1<_r-2<_r\cdots<_r0<_r1<_r2<_r\cdots$. For any $\pi\in\mathfrak{B}_n$, let $\operatorname{des}^B(\pi)$ and $\operatorname{ides}^B(\pi)$ be the number of descents and inverse descents in $\pi$ under the natural order, and let $\operatorname{des}_B(\pi)$ and $\operatorname{ides}_B(\pi)$ be the number of descents and inverse descents in $\pi$ under the $r$-order. In this paper, by investigating signed permutation grids under both the natural order and the $r$-order, we give combinatorial proofs for six recurrence formulas of the joint distribution of descents and inverse descents over the hyperoctahedral group $\mathfrak{B}_n$, the set in involutions of $\mathfrak{B}_n$ denoted by $\mathcal{I}_n^B$, and the set of fixed-point free involutions in $\mathfrak{B}_n$ denoted by $\mathcal{J}_n^B$, respectively. Some of these six formulas are new, and some reveal the combinatorial essences of the results obtained by Visontai, Moustakas and Cao-Liu through algebraic approaches such as quasisymmetric functions. Furthermore, from these formulas, we conclude that $(\operatorname{des}^B,\operatorname{ides}^B)$ and $(\operatorname{des}_B,\operatorname{ides}_B)$ are equidistributed over both $\mathfrak{B}_n$ and $\mathcal{I}_n^B$, but not on $\mathcal{J}_n^B$.

The pulsar B0458+46 was previously believed to have a distance of about 1.3$~$kpc and to be associated with a nearby supernova remnant, SNR HB9 (G160.9+2.6). We observe the neutral hydrogen (HI) absorption spectrum of PSR B0458+46 by using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), and detect two absorption lines at radial velocities of $V_{\rm LSR} = {-7.7}~{\rm km~s}^{-1}$ and $-28.1~{\rm km~s^{-1}}$. Based on the Galactic rotation curve with a modification factor correcting for the systematic stream in the anticenter region, we derive the kinematic distance of the farther absorption cloud, which is found to be located $2.7^{+0.9}_{-0.8}$ kpc away, just beyond the Perseus Arm. We also obtain a direct distance estimation of the absorption clouds, being $2.3_{-0.7}^{+1.1}$ kpc, based on a comparison of their velocity with the HI emission in the Perseus and Outer Arms that was well-defined by recently measured parallax tracers. As a result, we conclude that PSR B0458+46 should be located beyond the Perseus Arm, with a lower limit distance of 2.7 kpc, and therefore not associated with SNR HB9. The doubled distance indicates a deficiency of thermal electrons in the immediate outer Galaxy, with much less density than current models predict. Additionally, we detect a new high-velocity HI cloud in the direction of this pulsar.

The unprecedented sensitivity provided by the Five-hundred-meter Aperture Spherical radio Telescope (FAST) could shed light on studies of the magnetic field and plasma properties of brown dwarfs by catching polarized radio flares. With the FAST L-band 19-beam receiver, we observe a nearby dwarf stellar system 2MASSW J0746425 + 200032 which has been reported to show 4.86 GHz and 8.46 GHz radio flare emission. The L-band radio signals from the target are searched in both total intensity and circular polarization during the entire 147 min tracking observation. No radio flare down to a sensitivity of ∼13 mJy and ∼2 mJy (5σ) in Stokes I and V can be identified. The non-detection may lie in the intrinsic physical condition of the stellar system, e.g., the magnetic field strength and the electron density distribution and/or the sampling rate, which should be higher to reveal the sub-second structures but are smeared out with a lower rate in our observations.

G213.0$-$0.6 is a faint extended source situated in the anti-center region of the Galactic plane. It has been classified as a shell-type supernova remnant (SNR) based on its shell-like morphology, steep radio continuum spectrum, and high ratio of [S II]/H$\alpha$. With new optical emission line data of H$\alpha$, [S II], and [N II] recently observed by the Large Sky Area Multi-Object Fiber Spectroscopic Telescope, the ratios of [S II]/H$\alpha$ and [N II]/H$\alpha$ are re-assessed. The lower values than those previously reported put G213.0$-$0.6 around the borderline of SNR-HII region classification. We decompose the steep-spectrum synchrotron and the flat-spectrum thermal free-free emission in the area of G213.0$-$0.6 with multi-frequency radio continuum data. G213.0$-$0.6 is found to show a flat spectrum, in conflict with the properties of a shell-type SNR. Such a result is further confirmed by TT-plots made between the 863-MHz, 1.4-GHz, and 4.8-GHz data. Combining the evidence extracted in both optical and radio continuum, we argue that G213.0$-$0.6 is possibly not an SNR, but an HII region instead. The $V_{LSR}$ pertaining to the H$\alpha$ filaments places G213.0$-$0.6 approximately 1.9 kpc away in the Perseus Arm.

ABSTRACT G213.0−0.6 is a faint extended source situated in the anticentre region of the Galactic plane. It has been classified as a shell-type supernova remnant (SNR) based on its shell-like morphology, steep radio continuum spectrum, and high ratio of [S ii]/Hα. With new optical emission line data of Hα, [S ii], and [N ii] recently observed by the Large Sky Area Multi-Object Fiber Spectroscopic Telescope, the ratios of [S ii]/Hα and [N ii]/Hα are re-assessed. The lower values than those previously reported put G213.0−0.6 around the borderline of SNR-H ii region classification. We decompose the steep-spectrum synchrotron and the flat-spectrum thermal free-free emission in the area of G213.0−0.6 with multi-frequency radio continuum data. G213.0−0.6 is found to show a flat spectrum, in conflict with the properties of a shell-type SNR. Such a result is further confirmed by TT-plots made between the 863-MHz, 1.4-GHz, and 4.8-GHz data. Combining the evidence extracted in both optical and radio continuum, we argue that G213.0−0.6 is possibly not an SNR, but an H ii region instead. The VLSR pertaining to the Hα filaments places G213.0−0.6 approximately 1.9 kpc away in the Perseus Arm.

This article focuses on the Ullens Center for Contemporary Art as a case study, employing Jean Baudrillard's Consumer Society Theory to analyze the operation and transformation of the Chinese contemporary art market. The study's primary objectives are to dissect the intricacies of the Chinese contemporary art market's operation and its specific evolution path. Additionally, it offers recommendations for future developments and prospects within the contemporary art market, aiming to enhance the global dialogue of Chinese modern art. Baudrillard's Consumer Society Theory provides a strong theoretical foundation for scrutinizing the contemporary art market, enabling a deeper comprehension of its developmental trends. Through this analysis, the paper contributes to improving the quality of Chinese modern art and its international exchanges while bolstering confidence in Chinese culture.

Grasping the real-time and accurate downhole information is an important step for realizing optimized drilling, which is also the direction of many drilling companies. Because there are many types of signals with different amplitudes and frequencies that change all the time, in the meantime the signals are generated from sources far away from the ground as well as high temperature and high pressure appear in these positions, leading big challenges in measuring these signals. Measuring approach based on mud pressure pulse is one of the most popular methods used today. For this approach, sensors are placed downhole to monitor the information and the information is sent to the mud channel in the form of pressure pulse, then the sensors and systems on surface are used to treat these mud pulses. In this paper, the mechanism of the measuring the downhole information via mud pressure pulses is presented, including the emission of the downhole signals, the attenuation of the mud pressure in the mud channel, and the handling of the signals on surface. Based on the existing technology, some optimization measures are developed in the point structure of the mud channel, emission of the downhole signals, and disposing of the surface signals. In addition, the detailed operation procedures are also presented.

We discovered three large HII regions: G148.8+2.3, G149.5+0.0 and G169.9+2.0 in the Sino-German λ6 cm polarization survey of the Galactic plane. They have been identified based on the flat spectral indexes and the strong infrared emission properties.

Context. Pulsars scintillate. Dynamic spectra show brightness variation of pulsars in the time and frequency domain. Secondary spectra demonstrate the distribution of fluctuation power in the dynamic spectra. Aims. Dynamic spectra strongly depend on observational frequencies, but were often observed at frequencies lower than 1.5 GHz. Scintillation observations at higher frequencies help to constrain the turbulence feature of the interstellar medium over a wide frequency range and can detect the scintillations of more distant pulsars. Methods. Ten pulsars were observed at 2250 MHz (S-band) with the Jiamusi 66 m telescope to study their scintillations. Their dynamic spectra were first obtained, from which the decorrelation bandwidths and time scales of diffractive scintillation were then derived by autocorrelation. Secondary spectra were calculated by forming the Fourier power spectra of the dynamic spectra. Results. Most of the newly obtained dynamic spectra are at the highest frequency or have the longest time span of any published data for these pulsars. For PSRs B0540+23, B2324+60 and B2351+61, these were the first dynamic spectra ever reported. The frequencydependence of scintillation parameters indicates that the intervening medium can rarely be ideally turbulent with a Kolmogorov spectrum. The thin screen model worked well at S-band for the scintillation of PSR B1933+16. Parabolic arcs were detected in the secondary spectra of three pulsars, PSRs B0355+54, B0540+23 and B2154+40, all of which were asymmetrically distributed. The inverted arclets of PSR B0355+54 were seen to evolve along the main parabola within a continuous observing session of 12 hours, from which the angular velocity of the pulsar was estimated that was consistent with the measurement by very long baseline interferometry (VLBI).

Abstract We present a radio polarization study of the supernova remnant CTB 80 based on images at 1420 MHz from the Canadian Galactic Plane Survey, at 2695 MHz from the Effelsberg survey of the Galactic plane and at 4800 MHz from the Sino-German λ6 cm polarization survey of the Galactic plane. We obtained a rotation measure (RM) map using polarization angles at 2695 MHz and 4800 MHz as the polarization percentages are similar at these two frequencies. RM exhibits a transition from positive values to negative values along one of the shells hosting the pulsar PSR B1951+32 and its pulsar wind nebula. The reason for the change in sign remains unclear. We identified a partial shell structure, which is bright in polarized intensity but weak in total intensity. This structure could be part of CTB 80 or part of a new supernova remnant unrelated to CTB 80.

We search for the $\psi(4S)$ state in $B^\pm \ra \eta J/\psi K^\pm$ and $e^+e^- \ra \eta J/\psi$ based on the Belle measurements with the assumed mass $M=(4230\pm8)$ MeV/$c^2$ and width $\Gamma=(38\pm12)$ MeV. No significant signal is observed in the $\eta J/\psi$ mass spectra. The 90\% confidence level upper limit on the product branching fraction $\BR(B^\pm \ra \psi(4S)K^\pm)\BR(\psi(4S) \ra \eta J/\psi)<6.8\times 10^{-6}$ is obtained in $B^\pm \ra \eta J/\psi K^\pm$ decays. By assuming the partial width of $\psi(4S) \to e^+e^-$ being 0.63 keV, the branching fraction limit $\BR(\psi(4S) \ra \eta J/\psi) < 1.3\%$ is obtained at the 90\% confidence level in $e^+e^- \ra \eta J/\psi$, which is consistent with the theoretical prediction.

Context. Magnetic fields in the turbulent interstellar medium (ISM) are a key element in understanding Galactic dynamics, but there are many observational challenges. One useful probe for studying the magnetic field component parallel to the line of sight (LoS) is Faraday rotation of linearly polarized radio synchrotron emission, combined with H α observations. H ii regions are the perfect laboratories to probe such magnetic fields as they are localized in space, and are well-defined sources often with known distances and measurable electron densities. We chose the H ii region Sharpless 2–27 (Sh 2–27) as it is located at intermediate latitudes ( b ~ 23°), meaning that it suffers from little LoS confusion from other sources. In addition, it has a large angular diameter (~10°), enabling us to study the properties of its magnetic field over a wide range of angular scales. Aims. By using a map of the magnetic field strength along the LoS ( B ‖ )for the first time, we investigate the basic statistical properties of the turbulent magnetic field inside Sh 2–27. We study the scaling of the magnetic field fluctuations, compare it to the Kolmogorov scaling, and attempt to find an outer scale of the turbulent magnetic field fluctuations. Methods. We used the polarized radio synchrotron emission data from the S-band Polarization All-Sky Survey (S-PASS) at 2.3 GHz, which allowed us to test the impact of Sh 2–27 on diffuse Galactic synchrotron polarization. We estimated the rotation measure (RM) caused by the H ii region, using the synchrotron polarization angle. We used the H α data from the Southern H α Sky Survey Atlas to estimate the free electron density ( n e ) in the H ii region. Using an ellipsoid model for the shape of Sh 2–27, and with the observed RM and emission measure ( EM ), we estimated the LoS averaged B ‖ for each LoS within the ellipsoid. To characterize the turbulent magnetic field fluctuations, we computed a second-order structure function of B ‖ We compared the structure function to Kolmogorov turbulence, and to simulations of Gaussian random fields processed in the same way as the observations. Results. We present the first continuous map of B ‖ computed using the diffuse polarized radio emission in Sh 2–27. We estimate the median value of n e as 7.3 ± 0.1 cm −3 , and the median value of B ‖ as −4.5 ± 0.1 µG, which is comparable to the magnetic field strength in diffuse ISM. The slope of the structure function of the estimated B ‖ -map is found to be slightly steeper than Kolmogorov, consistent with our Gaussian-random-field B ‖ simulations revealing that an input Kolmogorov slope in the magnetic field results in a somewhat steeper slope in B ‖ .These results suggest that the lower limit to the outer scale of turbulence is 10 pc in the H ii region, which is comparable to the size of the computation domain. Conclusions. The structure functions of B ‖ fluctuations in Sh 2–27 show that the magnetic field fluctuations in this H ii region are consistent with a Kolmogorov-like turbulence. Comparing the observed and simulated B ‖ structure functions results in the estimation of a lower limit to the outer scale of the turbulent magnetic field fluctuations of 10 pc, which is limited by the size of the field of view under study. This may indicate that the turbulence probed here could actually be cascading from the larger scales in the ambient medium, associated with the interstellar turbulence in the general ISM, which is illuminated by the presence of Sh 2–27.

Using $(223.7\pm1.4)\times10^6$ J/$\psi$ events accumulated with the BESIII detector, we study $\eta_c$ decays to $\phi\phi$ and $\omega\phi$ final states. The branching fraction of $\eta_c\to\phi\phi$ is measured to be $Br(\eta_c\to\phi\phi)=(2.5\pm0.3^{+0.3}_{-0.7}\pm0.6)\times10^{-3}$, where the first uncertainty is statistical, the second is systematic, and the third is from the uncertainty of $Br(J/\psi\to\gamma\eta_c)$. No significant signal for the double OZI-suppressed decay of $\eta_c\to\omega\phi$ is observed, and the upper limit on the branching fraction is determined to be $Br(\eta_c\to\omega\phi)<2.5\times 10^{-4}$ at the 90\% confidence level.

Radio recombination lines (RRLs) are the best tracers of ionized gas. Simultaneous observations of multi-transitions of RRLs can significantly improve survey sensitivity. We conducted pilot RRL observations near the Sagittarius Arm tangent by using the 65-m Shanghai Tian Ma Radio Telescope (TMRT) equipped with broadband feeds and a digital backend. Six hydrogen RRLs (H96 H101α) at C band (6289 MHz–7319 MHz) were observed simultaneously toward a sky area of 2° × 1.2° by using on-the-fly mapping mode. These transitions were then stacked together for detection of ionized gas. Star forming complexes G48.6+0.1 and G49.5−0.3 were detected in the integrated intensity map. We found agreements between our measured centroid velocities and previous results for the 21 known HII regions in the mapped area. For more than 80 cataloged HII region candidates without previous RRL measurements, we obtained new RRL spectra at 30 targeted positions. In addition, we detected 25 new discrete RRL sources with spectral S/N σ, and they were not listed in the catalogs of previously known HII regions. The distances for 44 out of these 55 new RRL sources were estimated.

Aims. Most pulsar nulling observations have been conducted at frequencies lower than 1400 MHz. We aim to understand the nulling behaviors of pulsars at relatively high frequencies, and to decipher whether or not nulling is caused by a global change in the pulsar magnetosphere.Methods. We used the Jiamusi 66 m telescope to observe 20 bright pulsars at 2250 MHz with unprecedented lengths of time. We estimated the nulling fractions of these pulsars, and identified the null and emission states of the pulses. We also calculated the nulling degrees and scales of the emission-null pairs to describe the distributions of emission and null lengths.Results. Three pulsars, PSRs J0248+6021, J0543+2329, and J1844+00, are found to null for the first time. The details of null-to-emission and emission-to-null transitions within the pulse window are observed for the first time for PSR J1509+5531, which is a low-probability event. A complete cycle of long nulls with timescales of hours is observed for PSR J1709−1640. For most of these pulsars, the K-S tests of nulling degrees and nulling scales reject the hypothesis that null and emission are caused by random processes at high significance levels. Emission-null sequences of some pulsars exhibit quasi-periodic, low-frequency or featureless modulations, which might be related to different origins. During transitions between emission and null states, pulse intensities have diverse tendencies for variation. Significant correlations are found between respectively nulling fraction, nulling cadence, and nulling scale and the energy loss rate of the pulsars. Combined with the nulling fractions reported in the literature for 146 nulling pulsars, we find that statistically large nulling fractions are more tightly related to pulsar period than to characteristic age or energy-loss rate.

Context. The vast majority of Galactic supernova remnants (SNRs) were detected by their synchrotron radio emission. Recently, the evolved SNR G107.0+9.0 with a diameter of about 3° or 75 pc up to 100 pc in size was optically detected with an indication of faint associated radio emission. This SNR requires a detailed radio study. Aims. We aim to search for radio emission from SNR G107.0+9.0 by analysing new data from the Effelsberg 100-m and the Urumqi 25-m radio telescopes in addition to available radio surveys. Methods. Radio SNRs outside of the Galactic plane, where confusion is rare, must be very faint if they have not been identified so far. Guided by the H α emission of G107.0+9.0, we separated its radio emission from the Galactic large-scale emission. Results. Radio emission from SNR G107.0+9.0 is detected between 22 MHz and 4.8 GHz with a steep non-thermal spectrum, which confirms G107.0+9.0 as an SNR. Its surface brightness is among the lowest known for Galactic SNRs. Polarised emission is clearly detected at 1.4 GHz but is fainter at 4.8 GHz. We interpret the polarised emission as being caused by a Faraday screen associated with G107.0+9.0 and its surroundings. Its ordered magnetic field along the line of sight is below 1 μG. At 4.8 GHz, we identified a depolarised filament along the western periphery of G107.0+9.0 with a magnetic field strength along the line of sight B || ~ 15 μG, which requires magnetic field compression. Conclusions. G107.0+9.0 adds to the currently small number of known, evolved, large-diameter, low-surface-brightness Galactic SNRs. We have shown that such objects can be successfully extracted from radio-continuum surveys despite the dominating large-scale diffuse Galactic emission.

The CMS experiment has been designed with a 2-level trigger system, the Level 1 Trigger (L1), implemented on custom-designed electronics, and the High Level Trigger (HLT), a streamlined version of the CMS off-line reconstruction software running on a computer farm. We will present the performance with the specific algorithms developed to cope with the increasing LHC pile-up and bunch crossing rate using 13 TeV data during 2015, and prospects for improvements brought to both L1 and HLT strategies to meet the new challenges for 2016 scenarios with a peak instantaneous luminosity of $1.2 \times 10^{34} $cm$^{-2}$s$^{-1}$ and 30 pileup events.

After Prof. R. Wielebinski visited China in 1999, we started to plan the Sino-German λ6 cm polarization survey of the Galactic plane, using the Urumqi 25-m radio telescope of Xinjiang (formerly Urumqi) Astronomical Observatory, Chinese Academy of Sciences. It is a high-frequency complement of previous Effelsberg 21-cm and 11-cm surveys, using the same observing and processing methods. The telescope is located at an altitude of 2029 m above sea level at geographic longitude of 87°E and latitude 43°N. The dual-channel λ6 cm receiver with a polarimeter and a bandwidth of 600 MHz was designed by O. Lochner and constructed at the MPIfR in Germany with involvements by the Urumqi engineers M.Z. Chen and J. Ma. In August 2004, the receiver was installed at the secondary focus of the Urumqi 25-m telescope.

Analysis of data from the Experimental Investigation of Spacecraft Glow (EISG) and laboratory experiments associated with that experiment have provide a number of emission spectra from surface recombination of N and O. These constituents can be scavenged from the atmosphere. In addition, Monomethyl hydrazine thruster effluents interacting with the atmosphere are observed to produce large amounts of N and NO, likely through O collisions with exhaust products of vibrationally enhanced molecular nitrogen. These products produce both gas phase and surface (heterogeneous) reactions resulting in UV and FUV glows. The associated emissions arising from excited NO and other molecules have been observed and are reported.