Search

We report on the Insight-HXMT observations of the new black hole X-ray binary MAXI J1820+070 during its 2018 outburst. Detailed spectral analysis via the continuum fitting method shows an evolution of the inferred spin during its high soft sate. Moreover, the hardness ratio, the non-thermal luminosity and the reflection fraction also undergo an evolution, exactly coincident to the period when the inferred spin transition takes place. The unphysical evolution of the spin is attributed to the evolution of the inner disc, which is caused by the collapse of a hot corona due to condensation mechanism or may be related to the deceleration of a jet-like corona. The studies of the inner disc radius and the relation between the disc luminosity and the inner disc radius suggest that, only at a particular epoch, did the inner edge of the disc reach the innermost stable circular orbit and the spin measurement is reliable. We then constrain the spin of MAXI J1820+070 to be a*=0.2^{+0.2}_{-0.3}. Such a slowly spinning black hole possessing a strong jet suggests that its jet activity is driven mainly by the accretion disc rather than by the black hole spin., Comment: 14 pages, 13 figures, 5 tables, accepted for publication in MNRAS

Fast radio bursts (FRBs) are short pulses observed in radio band from cosmological distances. One class of models invoke soft gamma-ray repeaters (SGRs), or magnetars, as the sources of FRBs. Some radio pulses have been observed from some magnetars, however, no FRB-like events had been detected in association any magnetar burst, including one giant flare. Recently, a pair of FRB-like bursts (FRB 200428 hereafter) separated by milliseconds (ms) were detected from the general direction of the Galactic magnetar SGR J1935+2154. Here we report the detection of a non-thermal X-ray burst in the 1-250 keV energy band with the Insight-HXMT satellite, which we identify as emitted from SGR J1935+2154. The burst showed two hard peaks with a separation of 34 ms, broadly consistent with that of the two bursts in FRB 200428. The delay time between the double radio and X-ray peaks is about 8.57 s, fully consistent with the dispersion delay of FRB 200428. We thus identify the non-thermal X-ray burst is associated with FRB 200428 whose high energy counterpart is the two hard peaks in X-ray. Our results suggest that the non-thermal X-ray burst and FRB 200428 share the same physical origin in an explosive event from SGR J1935+2154., 24 pages, 9 figures, 6 tables; initial submission to a journal on May 9th, 2020. Significant changes include updated localization and detailed spectral evolution of the X-ray burst, and better determination of the two narrow X-ray peaks corresponding to the two radio pulses. Conclusions are strengthened. Nature Astronomy online on Feb. 18, 2021

A black hole X-ray binary produces hard X-ray radiation from its corona and disk when the accreting matter heats up. During an outburst, the disk and corona co-evolves with each other. However, such an evolution is still unclear in both its geometry and dynamics. Here we report the unusual decrease of the reflection fraction in MAXI J1820+070, which is the ratio of the coronal intensity illuminating the disk to the coronal intensity reaching the observer, as the corona is observed to contrast during the decay phase. We postulate a jet-like corona model, in which the corona can be understood as a standing shock where the material flowing through. In this dynamical scenario, the decrease of the reflection fraction is a signature of the corona's bulk velocity. Our findings suggest that as the corona is observed to get closer to the black hole, the coronal material might be outflowing faster., 11 pages, 5 figures; published in Nature Communications; An artist's impression of Figure 5 is updated here, and the animation is available at http://youbei.work/research/

Objectives The relationship between the 18FDG PET-CT maximum standard uptake value (SUVmax) and the type of lung adenocarcinoma is still not established. The aim of this study was to investigate the relationship between SUVmax value and histological grade and pathological subtype of lung adenocarcinoma, and to determine the optimum SUVmax cutoffs for distinguishing different histological grades. Materials and Methods The data of 618 lung adenocarcinoma patients were retrospectively analyzed. The relationship between SUVmax measured on preoperative 18FDG-PET-CT and the histological grade and pathological subtype was examined. The Kruskal-Wallis test was used to compare differences among groups, and the Bonferroni-Dunn test for pairwise comparison among groups. ROC analysis was applied to determine the optimal cut-off values for distinguishing different groups. In addition, the cut-off value was verified in an independent cohort of 85 consecutive lung adenocarcinoma cases. Results The SUVmax was significantly different between the low, intermediate, and high-grade groups(p Conclusion SUVmax can be used to predict pathological subtype and histological grade of lung adenocarcinoma. Thus, 18FDG PET-CT can serve as a noninvasive tool for precise diagnosis and help in the preoperative formulation of patient-specific treatment strategies.

Recently, the system parameters of Cygnus X-1, i.e., the black hole mass M, the orbital inclination i and the source distance D, have been updated. As the input constraints of the continuum-fitting method, it is necessary to refine the spin with these new parameters. The Hard X-ray Modulation Telescope (HXMT, also named Insight) was successfully launched on June 15th, 2017 in China. In this work, we analyzed spectra obtained by the Insight-HXMT during 2017-2018 and re-estimated the spin via the continuum-fitting method. We first re-estimated the spin using old parameters and found the dimensionless spin parameter to be a ⁎ > 0.934 (3σ), which is consistent with previous measurements both from the continuum-fitting and iron-line fitting methods ( Gou et al. 2011 , Gou et al. 2014 ; Fabian et al. 2012 , Walton et al. 2016 , Tomsick et al. 2018 ). Then, when the new parameters were applied, we obtained an increased spin: a ⁎ > 0.967 (3σ), which is also consistent with the recent measurement (Zhao et al. 2020, submitted to ApJ) and also confirms an extreme Kerr black hole lying in this system.

We present a detailed timing study of the brightest persistent X-ray source Sco X-1 using the data collected by the Hard X-ray Modulation Telescope ( I n s i g h t -HXMT) from July 2017 to August 2018. A complete Z-track hardness-intensity diagram (HID) is obtained. The normal branch oscillations (NBOs) at ∼ 6 Hz in the lower part of the normal branch (NB) and the flare branch oscillations (FBOs) at ∼ 16 Hz in the beginning part of the flaring branch (FB) are found in observations with the Low Energy X-ray Telescope (LE) and the Medium Energy X-ray Telescope (ME) of I n s i g h t -HXMT, while the horizontal branch oscillations (HBOs) at ∼ 40 Hz and the kilohertz quasi-periodic oscillations (kHz QPOs) at ∼ 800 Hz are found simultaneously above 20 keV for the first time on the horizontal branch (HB) by the High Energy X-ray Telescope (HE) and ME. We find that for all types of the observed QPOs, the centroid frequencies are independent of energy, while the root mean square (rms) increases with energy; the centroid frequencies of both the HBOs and kHz QPOs increase along the Z-track from the top to the bottom of the HB; and the NBOs show soft phase lags increasing with energy. A continuous QPO transition from the FB to NB in ∼ 200 s are also detected. Our results indicate that the non-thermal emission is the origin of all types of QPOs, the innermost region of the accretion disk is non-thermal in nature, and the corona is nonhomogeneous geometrically.

The High Energy X-ray telescope (HE) on-board the Hard X-ray Modulation Telescope (\textit{Insight}-HXMT) can serve as a wide Field of View (FOV) gamma-ray monitor with high time resolution ($\mu$s) and large effective area (up to thousands cm$^2$). We developed a pipeline to search for Gamma-Ray Bursts (GRBs), using the traditional signal-to-noise ratio (SNR) method for blind search and the coherent search method for targeted search. By taking into account the location and spectrum of the burst and the detector response, the targeted coherent search is more powerful to unveil weak and sub-threshold bursts, especially those in temporal coincidence with Gravitational Wave (GW) events. Based on the original method in literature, we further improved the coherent search to filter out false triggers caused by spikes in light curves, which are commonly seen in gamma-ray instruments (e.g. \textit{Fermi}/GBM, \textit{POLAR}). We show that our improved targeted coherent search method could eliminate almost all false triggers caused by spikes. Based on the first two years of \textit{Insight}-HXMT/HE data, our targeted search recovered 40 GRBs, which were detected by either \textit{Swift}/BAT or \textit{Fermi}/GBM but too weak to be found in our blind search. With this coherent search pipeline, the GRB detection sensitivity of \textit{Insight}-HXMT/HE is increased to about 1.5E-08 erg/cm$^2$ (200 keV$-$3 MeV). We also used this targeted coherent method to search \textit{Insight}-HXMT/HE data for electromagnetic (EM) counterparts of LIGO-Virgo GW events (including O2 and O3a runs). However, we did not find any significant burst associated with GW events., Comment: 12 pages, 14 figures, 5 tables; accepted for publication in MNRAS

BACKGROUND: Robotic-assisted thoracic surgery (RATS) has been widely used in the treatment of lung cancer. The perioperative outcomes of right upper lobectomy (RUL) using RATS and video-assisted thoracic surgery (VATS) were retrospectively investigated and compared. We aimed to summarize a single-center experience of RATS and 4-port unidirectional VATS in RUL, and to discuss the safety and the essentials of the surgery. METHODS: We retrospectively analyzed the 685 with non-small cell lung cancer (NSCLC) patients who underwent minimally invasive RUL in our center by the same surgical group from January 2015 to December 2019. Both RATS and VATS were performed with three ports with utility incision. The 685 participants were divided into RATS (335 cases) and VATS (350 cases) groups according to surgical method. Baseline characteristics and perioperative outcomes including dissected lymph nodes, postoperative duration of drainage, postoperative hospital stay, and incidence of postoperative complications were compared between the groups. RESULTS: In the 685 patients enrolled, the baseline characteristics were comparable, and no postoperative 30-day mortality or intraoperative blood transfusion were observed. Compared with VATS, RATS had less surgical duration (90.22±12.16 vs. 92.68±12.26 min, P

We report the energy-resolved broadband timing analysis of the black hole X-ray transient MAXI J1631-479 during its 2019 outburst from February 11 to April 9, using data from the Insight-Hard X-ray Modulation Telescope (Insight-HXMT), which caught the source from its hard intermediate state to the soft state. Thanks to the large effective area of Insight-HXMT at high energies, we are able to present the energy dependence of fast variability up to ~100 keV. Type-C quasi-periodic oscillations (QPOs) with frequency varying between 4.9 Hz and 6.5 Hz are observed in the 1-100 keV energy band. While the QPO fractional rms increases with photon energy from 1 keV to ~10 keV and remains more or less constant from ~10 keV to ~100 keV, the rms of the flat-top noise first increases from 1 keV to ~8 keV then drops to less than 0.1% above ~30 keV. We suggest that the disappearance of the broadband variability above 30 keV could be caused by the non-thermal acceleration in the Comptonizing plasma. At the same time, the QPOs could be produced by the precession of either a small-scale jet or a hot inner flow model., To be published in The Astrophysical Journal

The evidences for the influence of thermonuclear (type-I) X-ray bursts upon the surrounding environments in neutron star low-mass X-ray binaries (LMXB) were detected previously via spectral and timing analyses. Benefitting from a broad energy coverage of Insight-HXMT, we analyze one photospheric radius expansion (PRE) burst, and find an emission excess at soft X-rays. Our spectral analysis shows that, such an excess is not likely relevant to the disk reflection induced by the burst emission and can be attributed to an enhanced pre-burst/persistent emission. We find that the burst and enhanced persistent emissions sum up to exceed Eddington luminosity by ∼ 40 percentages. We speculate that the enhanced emission is from a region beyond the PRE radius, or through the Comptonization of the corona.

The Hard X-ray Modulation Telescope (HXMT) named Insight is China's first X-ray astronomical satellite, with the Low Energy X-ray Telescope (LE) as one of its main payloads onboard. The detectors of LE adopt swept charge device CCD236 using L-shaped transfer electrodes. To measure the time response distribution resulted from the continuous readout of charges in detection area along specific paths, a long exposure readout mode has been designed. In this mode, CCD236 firstly performs exposure without readout, then all charges generated in preceding exposure phase are read out completely. And an analysis of the photons readout time in this mode is carried out, to obtain the time response distribution.

In this paper, we presented a detailed timing analysis of a prominent outburst of 4U 0115+63 detected by \textit{Insight}-HXMT in 2017 August. The spin period of the neutron star was determined to be $3.61398\pm 0.00002$ s at MJD 57978. We measured the period variability and extract the orbital elements of the binary system. The angle of periastron evolved with a rate of $0.048\pm0.003$ $yr^{-1}$. The light curves are folded to sketch the pulse profiles in different energy ranges. A multi-peak structure in 1-10 keV is clearly illustrated. We introduced wavelet analysis into our data analysis procedures to study QPO signals and perform a detailed wavelet analysis in many different energy ranges. Through the wavelet spectra, we report the discovery of a QPO at the frequency $\sim 10$ mHz. In addition, the X-ray light curves showed multiple QPOs in the period of $\sim 16-32 $ s and $\sim 67- 200 $ s. We found that the $\sim100$ s QPO was significant in most of the observations and energies. There exist positive relations between X-ray luminosity and their Q-factors and S-factors, while the QPO periods have no correlation with X-ray luminosity. In wavelet phase maps, we found that the pulse phase of $\sim 67- 200 $ s QPO drifting frequently while the $\sim 16-32 $ s QPO scarcely drifting. The dissipation of oscillations from high energy to low energy was also observed. These features of QPOs in 4U 0115+63 provide new challenge to our understanding of their physical origins., 14 pages, 9 figures, and 6 tables. This work has been submitted to MNRAS after the referee's report

The Follow-up X-ray Telescope (FXT), a key payload onboard the Einstein Probe sallite (EP), is equipped with a Wolter-I x-ray focusing mirror system. We introduce the principle of such a mirror system and analyze the influence of the mirror gap in the multishell nested mirror of the FXT on the effective area, stray-light ratio, and vignetting. To ensure that no occlusion occurs within adjacent shells and minimize stray-light ratio, the size of the gap is set to a optimized value for corresponding shell. We finished a design of a 54-shell mirror system according to these results. The optical performance of the design was then simulated using a Monte Carlo algorithm and the ray-tracing principle. The simulation shows that the effective area is 414.5 ± 0.2 cm2 at 1.25 keV (considering the spider), and the field of view is 64 arcmin in diameter. These parameters meet the optical requirements of the FXT.

Based on Insight-HXMT data, we report on the pulse fraction evolution during the 2017–2018 outburst of the newly discovered first Galactic ultraluminous X-ray (ULX) source Swift J0243.6+6124. The pulse fractions of 19 observation pairs selected in the rising and fading phases with similar luminosity are investigated. The results show a general trend of the pulse fraction increasing with luminosity and energy at supercritical luminosity. However, the relative strength of the pulsation between each pair evolves strongly with luminosity. The pulse fraction in the rising phase is larger at luminosity below 7.71 × 1038 erg s−1, but smaller at above. A transition luminosity is found to be energy independent. Such a phenomenon is first confirmed by Insight-HXMT observations and we speculate that it may have relation with the radiation-pressure-dominated accretion disc.

The Einstein Probe (EP) is an X-ray astronomical mission mainly devoting to time-domain astronomy. There are two main scientific payloads onboard EP, the Wide Field X-ray Telescope (WXT) based on the lobster eye optics and the Follow-up X-ray Telescope (FXT). FXT contains two Wolter-1 mirrors with a pnCCD detector on each focus. The total effective area is about 600 cm2 and the energy range is 0.3-10 keV. The pnCCD detector cooled by a pulse tube cooler enables high-resolution spectroscopy and imaging combined with excellent time resolution. It will also have several working modes with time resolution ranging from tens of microseconds to 50 milliseconds. Currently, the FXT is in its qualification model phase. The mirror assemblies (STM and TCM) as well as the pnCCD EM module have been manufactured and tested.

We present the observational results from a detailed timing analysis of the black hole candidate EXO 1846–031 during its outburst in 2019 with the observations of Insight-HXMT, NICER and MAXI. This outburst can be classified roughly into four different states. Type-C quasi-periodic oscillations (QPOs) observed by NICER (about 0.1–6 Hz) and Insight-HXMT (about 0.7–8 Hz) are also reported in this work. Meanwhile, we study various physical quantities related to QPO frequency. The QPO rms–frequency relationship in the energy band 1–10 keV indicates that there is a turning pointing in frequency around 2 Hz, which is similar to that of GRS 1915+105. A possible hypothesis for the relationship above may be related to the inclination of the source, which may require a high inclination to explain it. The relationships between QPO frequency and QPO rms, hardness, total fractional rms and count rate have also been found in other transient sources, which can indicate that the origin of type–C QPOs is non-thermal.

Low-frequency quasi-periodic oscillations (LFQPOs) are commonly found in black hole X-ray binaries, and their origin is still under debate. The properties of LFQPOs at high energies (above 30 keV) are closely related to the nature of the accretion flow in the innermost regions, and thus play a crucial role in critically testing various theoretical models. The Hard X-ray Modulation Telescope (Insight-HXMT) is capable of detecting emissions above 30 keV, and is therefore an ideal instrument to do so. Here we report the discovery of LFQPOs above 200 keV in the new black hole MAXI J1820+070 in the X-ray hard state, which allows us to understand the behaviours of LFQPOs at hundreds of kiloelectronvolts. The phase lag of the LFQPO is constant around zero below 30 keV, and becomes a soft lag (that is, the high-energy photons arrive first) above 30 keV. The soft lag gradually increases with energy and reaches ~0.9s in the 150-200 keV band. The detection at energies above 200 keV, the large soft lag and the energy-related behaviors of the LFQPO pose a great challenge for most currently existing models, but suggest that the LFQPO probably originates from the precession of a small-scale jet., 36 pages, 12 figures, 3 tables; published in Nature Astronomy

Sirtuin 6 (SIRT6), a member of the sirtuin family, is a nicotinamide adenine dinucleotide (NAD(+))-dependent deacetylase that is involved in various physiological and pathological processes. SIRT6 is generally downregulated and linked to tumorigenesis in non-small cell lung carcinoma (NSCLC), thus regarded as a promising therapeutic target of NSCLC. In this study, we investigated whether MDL-800, an allosteric activator of SIRT6, exerted antiproliferation effect against NSCLC cells in vitro and in vivo. We showed that MDL-800 increased SIRT6 deacetylase activity with an EC(50) value of 11.0 ± 0.3 μM; MDL-800 (10–50 μM) induced dose-dependent deacetylation of histone H3 in 12 NSCLC cell lines. Treatment with MDL-800 dose dependently inhibited the proliferation of 12 NSCLC cell lines with IC(50) values ranging from 21.5 to 34.5 μM. The antiproliferation effect of MDL-800 was significantly diminished by SIRT6 knockout. Treatment with MDL-800 induced remarkable cell cycle arrest at the G(0)/G(1) phase in NSCLC HCC827 and PC9 cells. Furthermore, MDL-800 (25, 50 μM) enhanced the antiproliferation of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) in osimertinib-resistant HCC827 and PC9 cells as well as in patient-derived primary tumor cells, and suppressed mitogen-activated protein kinase (MAPK) pathway. In HCC827 cell-derived xenograft nude mice, intraperitoneal administration of MDL-800 (80 mg · kg(−1) · d(−1), for 14 days) markedly suppressed the tumor growth, accompanied by enhanced SIRT6-dependent histone H3 deacetylation and decreased p-MEK and p-ERK in tumor tissues. Our results provide the pharmacological evidence for future clinical investigation of MDL-800 as a promising lead compound for NSCLC treatment alone or in combination with EGFR-TKIs.

The Insight -Hard X-ray Modulation Telescope ( Insight -HXMT) is a broadband X-ray and γ-ray (1-3000 keV) astronomy satellite. One of its three main telescopes is the High Energy X-ray telescope (HE). The main detector plane of HE comprises 18 NaI(Tl)/CsI(Na) phoswich detectors, where NaI(Tl) is used as the primary detector to measure ~ 20-250 keV photons incident from the field of view (FOV) defined by collimators, and CsI(Na) is used as the active shielding detector to NaI(Tl) by pulse shape discrimination. Additionally, CsI(Na) is used as an omnidirectional γ-ray monitor. The HE collimators have a diverse FOV, i.e. 1.1°×5.7° (15 units), 5.7°×5.7° (2 units), and blocked (1 unit). Therefore, the combined FOV of HE is approximately 5.7°×5.7°. Each HE detector has a diameter of 190 mm resulting in a total geometrical area of approximately 5100 cm2, and the energy resolution is ~15% at 60 keV. For each recorded X-ray event by HE, the timing accuracy is less than 10 μs and the dead-time is less than 10 μs. HE is used for observing spectra and temporal variability of X-ray sources in the 20-250 keV band either by pointing observations for known sources or scanning observations to unveil new sources. Additionally, HE is used for monitoring the γ-ray burst in 0.2-3 MeV band. This paper not only presents the design and performance of HE instruments but also reports results of the on-ground calibration experiments.

As China's first X-ray astronomical satellite, the Hard X-ray Modulation Telescope (HXMT), which was dubbed as Insight-HXMT after the launch on June 15, 2017, is a wide-band (1-250 keV) slat-collimator-based X-ray astronomy satellite with the capability of all-sky monitoring in 0.2-3 MeV. It was designed to perform pointing, scanning and gamma-ray burst (GRB) observations and, based on the Direct Demodulation Method (DDM), the image of the scanned sky region can be reconstructed. Here we give an overview of the mission and its progresses, including payload, core sciences, ground calibration/facility, ground segment, data archive, software, in-orbit performance, calibration, background model, observations and some preliminary results., 29 pages, 40 figures, 6 tables, to appear in Sci. China-Phys. Mech. Astron. arXiv admin note: text overlap with arXiv:1910.04434

We report on our analysis of the 2019 outburst of the X-ray accreting pulsar 4U 1901+03 observed with Insight-HXMT and NICER. Both spectra and pulse profiles evolve significantly in the decaying phase of the outburst. Dozens of flares are observed throughout the outburst. They are more frequent and brighter at the outburst peak. We find that the flares, which have a duration from tens to hundreds of seconds, are generally brighter than the persistent emission by a factor of $\sim$ 1.5. The pulse profile shape during the flares can be significantly different than that of the persistent emission. In particular, a phase shift is clearly observed in many cases. We interpret these findings as direct evidence of changes of the pulsed beam pattern, due to transitions between the sub- and super-critical accretion regimes on a short time scale. We also observe that at comparable luminosities the flares' pulse profiles are rather similar to those of the persistent emission. This indicates that the accretion on the polar cap of the neutron star is mainly determined by the luminosity, i.e., the mass accretion rate., 11 pages, 8 figures, accepted for publication in MNRAS

A link between magnetars and fast radio burst (FRB) sources has finally been established. In this context, one of the open issues is whether/which sources of extra galactic FRBs exhibit X/gamma-ray outbursts and whether it is correlated with radio activity. We aim to constrain possible X/gamma-ray burst activity from one of the nearest extragalactic FRB sources currently known over a broad energy range, by looking for bursts over a range of timescales and energies that are compatible with being powerful flares from extragalactic magnetars. We followed up the as-yet nearest extragalactic FRB source at a mere 149 Mpc distance, the periodic repeater FRB180916.J0158+65, during the active phase on February 4-7, 2020, with the Insight-Hard X-ray Modulation Telescope (HXMT). Taking advantage of the combination of broad band, large effective area, and several independent detectors available, we searched for bursts over a set of timescales from 1 ms to 1.024 s with a sensitive algorithm, that had previously been characterised and optimised. Moreover, through simulations we studied the sensitivity of our technique in the released energy-duration phase space for a set of synthetic flares and assuming different energy spectra. We constrain the possible occurrence of flares in the 1-100 keV energy band to E, 10 pages, 3 figures, accepted by A&A

We investigate the absorption and emission features in observations of GX 301-2 detected with Insight-HXMT/LE in 2017-2019. At different orbital phases, we found prominent Fe Kalpha, Kbeta and Ni Kalpha lines, as well as Compton shoulders and Fe K-shell absorption edges. These features are due to the X-ray reprocessing caused by the interaction between the radiation from the source and surrounding accretion material. According to the ratio of iron lines Kalpha and Kbeta, we infer the accretion material is in a low ionisation state. We find an orbital-dependent local absorption column density, which has a large value and strong variability around the periastron. We explain its variability as a result of inhomogeneities of the accretion environment and/or instabilities of accretion processes. In addition, the variable local column density is correlated with the equivalent width of the iron Kalpha lines throughout the orbit, which suggests that the accretion material near the neutron star is spherically distributed., Comment: 10 pages, 5 figures, 2 tables, accepted for publication in MNRAS

LE is the low energy telescope of Insight-HXMT. It uses swept charge devices (SCDs) to detect soft X-ray photons. The time response of LE is caused by the structure of SCDs. With theoretical analysis and Monte Carlo simulations we discuss the influence of LE time response (LTR) on the timing analysis from three aspects: the power spectral density, the pulse profile and the time lag. After the LTR, the value of power spectral density monotonously decreases with the increasing frequency. The power spectral density of a sinusoidal signal reduces by a half at frequency 536 Hz. The corresponding frequency for QPO signals is 458 Hz. The Root mean square (RMS) of QPOs holds the similar behaviour. After the LTR, the centroid frequency and full width at half maxima (FWHM) of QPOs signals do not change. The LTR reduces the RMS of pulse profiles and shifts the pulse phase. In the time domain, the LTR only reduces the peak value of the crosscorrelation function while it does not change the peak position. Thus it will not affect the result of the time lag. When considering the time lag obtained from two instruments and one among them is LE, a 1.18 ms lag is expected caused by the LTR. The time lag calculated in the frequency domain is the same as that in the time domain., Comment: 11 pages, 9 figures

We constructed a comprehensive model atom for NeI -- NeII using the most up-to-date atomic data available and evaluated the non-local thermodynamic equilibrium (NLTE) line formation for NeI and NeII in classical 1D models representing the atmospheres of B-type stars. We find that the large NLTE strengthening of the NeI lines corresponding to the 2p$^5$3p $-$ 2p$^5$3s transitions array occurs due to extremely small photoionization cross-sections of 2p$^5$3s levels that leads to strong overpopulation of these levels relative to their LTE populations. The deviations from LTE for the most NeII lines are small and do not exceed 0.11~dex in the absolute value. We analysed 20 lines of NeI and 13 lines of NeII for twenty-four B-type stars in the temperature range of 10\,400 $\le$ \Teff\ $\le$ 33\,400~K. For five stars, the NLTE leads to consistent abundances of NeI and NeII, while the difference in LTE abundance can reach up to 0.50~dex. The using of the experimental oscillator strengths recently measured by Piracha et al. (2015) leads to smaller line-by-line scatter for the most investigated stars. The averaged neon abundance in twenty-four B-type stars in solar neighborhood is 8.02$\pm$0.05. This value may provide indirect constraints on solar photospheric neon abundance., Comment: 20 pages, 9 figures, accepted to Astrophysical Journal

The relationship between theThe data of 618 lung adenocarcinoma patients were retrospectively analyzed. The relationship between SUVmax measured on preoperativeThe SUVmax was significantly different between the low, intermediate, and high-grade groups(p.001). SUVmax value increased with increase in the degree of malignancy. The optimal cut-off value for identifying low-grade tumors was 2.01 (sensitivity 90.4%, specificity 86.9%, area under the curve [AUC] = 0.928, 95% confidence interval: 0.91-0.95; p.001). The optimal cutoff SUVmax value for identifying high-grade tumors was 7.41 (sensitivity 79.8%, specificity 73.5%, AUC = 0.830, 95% confidence interval: 0.79-0.87; p.001). The validation experiment showed that the coincidence rate was 88.89% in the low-level group, 64.15% in the middle-level group, and 78.57% in the high-level group.SUVmax can be used to predict pathological subtype and histological grade of lung adenocarcinoma. Thus

Tian-Xiang Chen,1 Bigyan Pudasaini,1 Jian Guo,2 Su-Gang Gong,1 Rong Jiang,1 Lan Wang,1 Qin-Hua Zhao,1 Wen-Hui Wu,1 Ping Yuan,1 Jin-Ming Liu1 1Department of Cardio-Pulmonary Circulation, Shanghai Pulmonary Hospital, Tongji University, Shanghai, People’s Republic of China; 2Department of Pulmonary Function Test, Shanghai Pulmonary Hospital, Tongji University, Shanghai, People’s Republic of China Background: Sex differences in chronic thromboembolic pulmonary hypertension (CTEPH) have been revealed in few studies. Although right heart catheterization (RHC) is the gold standard for clinical diagnosis and assessment of prognosis in pulmonary hypertension (PH), cardiopulmonary exercise testing (CPET) has been a more widely used assessment of functional capacity, disease severity, prognosis, and treatment response in PH. We hypothesized that the “sex-specific” CPET indices could estimate the severity of inoperable CTEPH.Methods: Data were retrieved for 33 male (age, mean ± standard deviation [SD] =62.5±13.4 years) and 40 female (age, mean ± SD =56.3±11.8 years) patients with stable CTEPH who underwent both RHC and CPET at Shanghai Pulmonary Hospital from February 2010 to February 2016. Univariate and forward/backward multiple stepwise regression analysis was performed to assess the predictive value of CPET indices to hemodynamic parameters. Event-free survival was estimated using the Kaplan–Meier method and analyzed with the log-rank test. Cox proportional hazards models were performed to determine the independent event-free survival predictors.Results: Numerous CPET parameters were different between male and female patients with CTEPH and the control group. There were no significant differences in both clinical variables and RHC parameters between male and female patients with CTEPH. O2 pulse, workload, minute ventilation (VE), and end-tidal partial pressure of O2 (PETO2) at anaerobic threshold, as well as peak O2 pulse, workload, VE, and nadir VE/CO2 were significantly higher in male patients than in female patients (P

Cardiopulmonary exercise testing (CPET) has been used for prognosis in idiopathic pulmonary arterial hypertension (IPAH). We explored whether sex differences had an impact on prognostic assessments of CPET in IPAH. Data were retrieved from 21 male and 36 female incident IPAH patients who underwent both right heart catheterization and CPET from 2010 to 2016 at Shanghai Pulmonary Hospital. Cox proportional hazards analysis was used to assess the prognostic value of CPET. The mean duration of follow-up was 22±15 months. Nine men and 15 women had an event. The differences in clinical parameters in the whole population were not the same as the inter-subgroup differences. Event-free women had significantly higher cardiac output, lower pulmonary vascular resistance and percentage of predicted FVC compared with event men (all P

We report on analysis of observations of the bright transient X-ray pulsar \src obtained during its 2017-2018 giant outburst with Insight-HXMT, \emph{NuSTAR}, and \textit{Swift} observatories. We focus on the discovery of a sharp state transition of the timing and spectral properties of the source at super-Eddington accretion rates, which we associate with the transition of the accretion disk to a radiation pressure dominated (RPD) state, the first ever directly observed for magnetized neutron star. This transition occurs at slightly higher luminosity compared to already reported transition of the source from sub- to super-critical accretion regime associate with onset of an accretion column. We argue that this scenario can only be realized for comparatively weakly magnetized neutron star, not dissimilar to other ultra-luminous X-ray pulsars (ULPs), which accrete at similar rates. Further evidence for this conclusion is provided by the non-detection of the transition to the propeller state in quiescence which strongly implies compact magnetosphere and thus rules out magnetar-like fields., Submitted to MNRAS

We present a study of timing properties of the accreting pulsar 2S 1417-624 observed during its 2018 outburst, based on Swift/BAT, Fermi/GBM, Insight-HXMT and NICER observations. We report a dramatic change of the pulse profiles with luminosity. The morphology of the profile in the range 0.2-10.0keV switches from double to triple peaks at $\sim2.5$ $\rm \times 10^{37}{\it D}_{10}^2\ erg\ s^{-1}$ and from triple to quadruple peaks at $\sim7$ $\rm \times 10^{37}{\it D}_{10}^2\ erg\ s^{-1}$. The profile at high energies (25-100keV) shows significant evolutions as well. We explain this phenomenon according to existing theoretical models. We argue that the first change is related to the transition from the sub to the super-critical accretion regime, while the second to the transition of the accretion disc from the gas-dominated to the radiation pressure-dominated state. Considering the spin-up as well due to the accretion torque, this interpretation allows to estimate the magnetic field self-consistently at $\sim7\times 10^{12}$G., 7 pages, 4 figures, 1 tables, accepted for publication in MNRAS

The recently discovered neutron star transient Swift J0243.6+6124 has been monitored by {\it the Hard X-ray Modulation Telescope} ({\it Insight-\rm HXMT). Based on the obtained data, we investigate the broadband spectrum of the source throughout the outburst. We estimate the broadband flux of the source and search for possible cyclotron line in the broadband spectrum. No evidence of line-like features is, however, found up to $\rm 150~keV$. In the absence of any cyclotron line in its energy spectrum, we estimate the magnetic field of the source based on the observed spin evolution of the neutron star by applying two accretion torque models. In both cases, we get consistent results with $B\rm \sim 10^{13}~G$, $D\rm \sim 6~kpc$ and peak luminosity of $\rm >10^{39}~erg~s^{-1}$ which makes the source the first Galactic ultraluminous X-ray source hosting a neutron star., published

We present the analysis of the brightest flare that was recorded in the \emph{Insight}-HMXT data set, in a broad energy range (2$-$200 keV) from the microquasar GRS~1915+105 during an unusual low-luminosity state. This flare was detected by \emph{Insight}-HXMT among a series of flares during 2 June 2019 UTC 16:37:06 to 20:11:36, with a 2-200 keV luminosity of 3.4$-$7.27$\times10^{38}$ erg s$^{-1}$. Basing on the broad-band spectral analysis, we find that the flare spectrum shows different behaviors during bright and faint epochs. The spectrum of the flare can be fitted with a model dominated by a power-law component. Additional components show up in the bright epoch with a hard tail and in the faint epoch with an absorption line $\sim$ 6.78 keV. The reflection component of the latter is consistent with an inner disk radius $\sim$ 5 times larger than that of the former. These results on the giant flare during the "unusual" low-luminosity state of GRS~1915+105 may suggest that the source experiences a possible fast transition from a jet-dominated state to a wind-dominated state. We speculate that the evolving accretion disk and the large-scale magnetic field may play important roles in this peculiar huge flare.

Background Pressure sensors have been used for sleeping posture detection, which meet privacy requirements. Most of the existing techniques for sleeping posture recognition used force-sensitive resistor (FSR) sensors. However, lower limbs cannot be recognized accurately unless thousands of sensors are deployed on the bedsheet. Method We designed a sleeping posture recognition scheme in which FSR sensors were deployed on the upper part of the bedsheet to record the pressure distribution of the upper body. In addition, an infrared array sensor was deployed to collect data for the lower body. Posture recognition was performed using a fuzzy c-means clustering algorithm. Six types of sleeping body posture were recognized from the combination of the upper and lower body postures. Results The experimental results showed that the proposed method achieved an accuracy of above 88%. Moreover, the proposed scheme is cost-efficient and easy to deploy. Conclusions The proposed sleeping posture recognition system can be used for pressure ulcer prevention and sleep quality assessment. Compared to wearable sensors and cameras, FSR sensors and infrared array sensors are unobstructed and meet privacy requirements. Moreover, the proposed method provides a cost-effective solution for the recognition of sleeping posture.

This paper presents a vision-assisted human motion analysis method that can be used to recognize in-bed preparatory motions for bed-exit. In this work, a 3D convolutional neural network was applied to predict sequential motions from ultra-low resolution (32 × 24 pixels) clips composed of depth images, which meets both privacy and computational efficiency requirements. The experimental results showed that the system effectively recognized key motions of bed-exit before bed-leaving. Moreover, these motions were applied to bed-exit prediction in several cases of disturbance and for beds of different structures, and the system accurately predicted bed-exit.

This paper presents a vision-assisted human motion analysis method by which to classify unknown preparatory motions for bed exit. A convolutional neural network was applied to identify the existence of essential postures between two meaningful sequential motions from low-resolution depth images. The preliminary experimental results showed that sequential images of bed exit preparatory motions can be classified as essential motion states, which is useful for construction of the states of a hidden Markov model for bed exit prediction.

Background Typical radio frequency identification (RFID) access control system can be ineffective if an unauthorized person tailgates an authorized person through an access area. Objective To propose a system by using indoor locating and tracking techniques address this problem, which is to prevent unauthorized Alzheimer's and dementia patients from getting lost including by tailgating. Methods To achieve accurate target location, passive RFID deployment strategy is studied and a fingerprinting based passive RFID localization algorithm is proposed. The proposed system was evaluated in a building environment to simulate the performance of access control. RFID reader was installed on ceiling near the access area and tags were stitched on both shoulders of the experiment subject's garments. Results The probability of the error distance within 0.3 m achieved 97% in the warning area; the location precision achieved 97% within 0.4 m in the monitoring area. Conclusions The result showed that if an unauthorized person enters the restricted area, the system can initiate an alert signal accurately. Therefore, the proposed system is very suitable to be used in nursing home or hospital to prevent unauthorized personnel and assets entering/exiting a confined location.

In this paper, we propose a deep convolutional neural network model for in-bed behavior recognition and bed-exit prediction. This model extracts features for training from depth images taken by depth cameras in two categories: in-bed images taken several time intervals before a patient gets out of bed, and usual in-bed activity images. The depth camera-based model features grayscale and low-resolution images, and excels at discarding unnecessary details such as background information beyond the target's contour. The proposed model was proven to be computationally efficient, which is crucial for analyzing and predicting the category of new images in real time.

Background: Many studies have highlighted sex preponderance in idiopathic pulmonary arterial hypertension (IPAH). It is well established that there are differences in exercise capacities in the two sexes but how much of that difference reflects on disease severity or correlates to markers of severity in the two sexes is still not clear. Right heart catheterization (RHC) and cardiopulmonary exercise testing (CPET) have been widely used for assessing functional capacity, prognosis and treatment response in IPAH. We aimed to investigate the ‘sex-specific’ CPET parameters in relation to hemodynamics in IPAH. Methods: Data were retrieved from 30 males and 53 females [mean ± standard deviation (SD) age: 39.6 ± 17.2 and 37.5 ± 12.0] stable IPAH patients who underwent both RHC and CPET at Shanghai Pulmonary Hospital from 2010 to 2016. Univariate and forward/backward multiple stepwise regression analysis was performed to assess the prognostic value of CPET and hemodynamic parameters. Results: There were no significant differences in clinical variables between men and women. Peak workload, peak oxygen uptake, anaerobic threshold (AT), peak minute ventilation, carbon dioxide output, O2 pulse and oxygen uptake efficiency slope were significantly higher in men compared with women ( p < 0.05). Several CPET indexes correlated with hemodynamics. Pulmonary vascular resistance (PVR) and cardiac output (CO) were distinctly different between the sexes. Peak end-tidal partial pressure of CO2 (PETCO2) was an independent predictor of PVR elevation in all patients and in men. Peak maximum oxygen consumption (VO2) was independently predictive of CO decline in all patients and in men. Only peak O2 pulse was an independent predictor of increased PVR and decreased CO in women. Conclusions: Even after adjusting for age, body mass index and World Health Organization functional class, different CPET parameters correlated with PVR elevation and CO decline in men and women differently, which could potentially better predict severity in men and women with IPAH.

Finding the electromagnetic (EM) counterpart of binary compact star merger, especially the binary neutron star (BNS) merger, is critically important for gravitational wave (GW) astronomy, cosmology and fundamental physics. On Aug. 17, 2017, Advanced LIGO and \textit{Fermi}/GBM independently triggered the first BNS merger, GW170817, and its high energy EM counterpart, GRB 170817A, respectively, resulting in a global observation campaign covering gamma-ray, X-ray, UV, optical, IR, radio as well as neutrinos. The High Energy X-ray telescope (HE) onboard \textit{Insight}-HXMT (Hard X-ray Modulation Telescope) is the unique high-energy gamma-ray telescope that monitored the entire GW localization area and especially the optical counterpart (SSS17a/AT2017gfo) with very large collection area ($\sim$1000 cm$^2$) and microsecond time resolution in 0.2-5 MeV. In addition, \textit{Insight}-HXMT quickly implemented a Target of Opportunity (ToO) observation to scan the GW localization area for potential X-ray emission from the GW source. Although it did not detect any significant high energy (0.2-5 MeV) radiation from GW170817, its observation helped to confirm the unexpected weak and soft nature of GRB 170817A. Meanwhile, \textit{Insight}-HXMT/HE provides one of the most stringent constraints (~10$^{-7}$ to 10$^{-6}$ erg/cm$^2$/s) for both GRB170817A and any other possible precursor or extended emissions in 0.2-5 MeV, which help us to better understand the properties of EM radiation from this BNS merger. Therefore the observation of \textit{Insight}-HXMT constitutes an important chapter in the full context of multi-wavelength and multi-messenger observation of this historical GW event., Comment: accepted by Science China - Physics, Mechanics & Astronomy. Planned to publish on Oct 17, but postponed due to a problem on pdf file

The three-level discontinuous pulse-width modulation (DPWM) which can reduce switching frequency while restrain the switching loss of high power converters was proposed. Space- vector discontinuous modulation (SVDM) suitable for digital implement was also presented. Detailed analysis were given to verify the control performance of the two recommended SVDM methods and traditional space vector modulation (SVM) in switching loss and harmonic characteristic field. Three- level neutral-point-clamped (neutral-point-clamped, NPC) SVDM rectifiers were designed to evaluate their behavior in neutral-point potential control, robustness and static and dynamic response. The correctness and feasibility of the proposed control scheme are verified by the simulating and experimental tests.

Contact resistance is an essential cause of electrical equipment joint heating. An experimental platform was built to measure and compare temperature and contact resistance of memory alloy spring washers and ordinary spring washers when heated by taking the same heavy current, on condition that both of the counterparts had the same initial contact resistance and temperature. Results showed that memory alloy washer were more helpful to limit the joint temperature rise by reducing contact resistance from their features of tempting to restore to original shape when heated to a high temperature. Therefore, the memory alloy washers were proved to have remarkable effect on ensuring safety of electric power equipments and reducing energy loss.

Due to its good formability characteristics, such as high strength, high initial work hardening rate, as well as continuous yielding, thin-walled DP steel possesses great advantages of weight loss and security, and has been used to replace ordinary steel for automotive parts manufacturing by a lot of automotive industry. But along with the improvement of the performance of the strength, the high strength steels formability is worsened dramatically, and failure and fracture often occurs in its cold stamping process. So, hot stamping technology must be adopted to make the formability available. In the paper, it took the hot stamping process of DP steel engine hood for example and took DP800 as object of research. The forming limit, variation of major strain, minor strain and thickness, as well as the potential equality defects were analyzed by using eta/DYNAFORM software. The research results show that duplex steel plate can meet the performance requirements of car engine dumping plank forming, which offers theory basis for the production of similar parts.

Pattern of number of PD events ("NE" for short) variation detected by UHF online monitoring was found through experiments, demonstrating that in the first half life of oil-paper insulation the NE value declined at the beginning and then kept stable, while it increased sharply in the later half. Least square linear regression was applied to calculate the changing rate ("CR" for short) of the latest 168 measurements of NE, which turned out to be an appropriate indicator of life stage for its monotonicity over time from the initiation of PD till final breakdown. The Grubbs method was also applied to exclude erroneous data and to determine the credible variation of CRs.