Search

Context. 4U 1543–47 is one of a handful of known black hole candidates located in the Milky Way galaxy. It underwent a very luminous outburst in 2021, reaching a peak intensity of ~9 Crab, as observed by the Monitor of All-sky Image (MAXI), and exceeding twice its Eddington luminosity. Aims. The unprecedented bright outburst of 4U 1543–47 provides a unique opportunity to test the behavior of accretion disk models at high luminosities and accretion rates. In addition, we explore the possibility of constraining the spin of the source at high accretion rates, given that the previous spin measurements of 4U 1543–47 are largely inconsistent with each other. Methods. We measure the spectral evolution of the source throughout its outburst as observed by Insight-HXMT, and compare the behavior of both the thin-disk model kerrbb2 and the slim disk model slimbh up to the Eddington limit for two different values of disk α-viscosity. In addition, given the behavior of these two models, we identify two "golden" epochs in which it is most suitable to measure the spin with the continuum fitting method. Results. We find evidence of a disk state transition from a thicker slim disk to a thin disk occurring around 1 LEdd from fits to the luminosity-temperature relation. We obtain consistent and constant spin measurements from both slimbh and kerrbb2 as the luminosity varies towards the Eddington limit, implying the recovery of thin-disk solutions above the traditional thin-disk criterion of 30% LEdd. We constrain the spin to a* = 0.65−0.24+0.14, assuming an α-viscosity = 0.01 from both Insight-HXMT and NICER observations from the above-mentioned "golden" epochs where the condition of the disk being truncated at the innermost stable circular orbit is most closely met. [ABSTRACT FROM AUTHOR]

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 Insightâˆ'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 a frequency varying between 4.9 and 6.5 Hz are observed in the 1â€"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 and 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 nonthermal 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. [ABSTRACT FROM AUTHOR]

The effects of low-density polyethylene (LDPE) and a zinc-modified biochar catalyst on lignin pyrolysis were analyzed by thermogravimetric analysis (TGA). Thermal decomposition analysis disclosed that lignin and LDPE co-pyrolysis was more complicated than pyrolysis of lignin alone, addition of the catalyst caused a decrease in reaction temperature and a slight increase in the conversion rate, and most of the compounds decomposed at 260°C for lignin alone and at about 450°C for the lignin/LDPE blend. The synergistic effect between lignin and LDPE in co-pyrolysis with the catalyst was also analyzed. The kinetic parameters indicated that lignin pyrolysis was a third-order reaction, while lignin/LDPE co-pyrolysis was a second-order reaction. Addition of LDPE to lignin during pyrolysis lowered the activation energy from 49.10 to 30.26 kJ mol-1. Analysis of the reaction kinetics revealed that the reaction rate improved with addition of the catalyst. [ABSTRACT FROM AUTHOR]

To systematically review the efficacy of hCG and LHRH on testicular descent in boys with cryptorchidism, comprehensive search was performed to identify randomized controlled trials (RCTs) in PubMed, EMBASE, the Cochrane Library, Wanfang Database, and China National Knowledge Infrastructure (CNKI) up to March 2014. Outcomes included testicular complete descent rate (TCDR) and cure rate of patients. Study quality was evaluated using the Jadad scale. Meta-analysis was performed using Review Manager software. finally, 13 studies were included. hCG and LHRH increased TCDR comparing with control group. The success rate of hCG and LHRH was 24 and 19 %, respectively. Further, hCG and LHRH had significant effect on bilateral cryptorchidism, but not on unilateral cryptorchidism. All side effects were transitory and not severe, but if they have long-term harms were not clear. hCG and LHRH can effectively increase TCDR and there was no significant difference between them. However, the hormones cannot be recommended for everyone because of their low success rates and potential long-term harms. Further studies are needed to determine the efficacy of hormonal treatment for subtypes of cryptorchidism. [ABSTRACT FROM AUTHOR]

Context: Raising public awareness of the importance of social determinants of health (SDH) and health disparities presents formidable communication challenges. Methods: This article reviews three message strategies that could be used to raise awareness of SDH and health disparities: message framing, narratives, and visual imagery. Findings: Although few studies have directly tested message strategies for raising awareness of SDH and health disparities, the accumulated evidence from other domains suggests that population health advocates should frame messages to acknowledge a role for individual decisions about behavior but emphasize SDH. These messages might use narratives to provide examples of individuals facing structural barriers (unsafe working conditions, neighborhood safety concerns, lack of civic opportunities) in efforts to avoid poverty, unemployment, racial discrimination, and other social determinants. Evocative visual images that invite generalizations, suggest causal interpretations, highlight contrasts, and create analogies could accompany these narratives. These narratives and images should not distract attention from SDH and population health disparities, activate negative stereotypes, or provoke counterproductive emotional responses directed at the source of the message. Conclusions: The field of communication science offers valuable insights into ways that population health advocates and researchers might develop better messages to shape public opinion and debate about the social conditions that shape the health and well-being of populations. The time has arrived to begin thinking systematically about issues in communicating about SDH and health disparities. This article offers a broad framework for these efforts and concludes with an agenda for future research to refine message strategies to raise awareness of SDH and health disparities. [ABSTRACT FROM AUTHOR]

Describes an improved inverse gas chromatographic method involving the use of a mass-specific detector for the determination of the glass transition temperature of polymeric materials. Benefits of this method; What has resulted from the method; Information on two methods for the evaluation of Tg; Interpretation of the chromatographic retention mechanisms of solute probes in glassy and rubbery polymers; What the method concluded.

The black hole X-ray binary source 4U 1543–47 experienced a super-Eddington outburst in 2021, reaching a peak flux of up to ∼1.96 × 10−7 erg cm−2 s−1 (∼8.2 Crab) in the 2−10 keV band. Soon after the outburst began, it rapidly transitioned into the soft state. Our goal is to understand how the accretion disk structure deviates from a standard thin disk when the accretion rate is near Eddington. To do so, we analyzed spectra obtained from quasi-simultaneous observations conducted by the Hard X-ray Modulation Telescope (Insight-HXMT), the Nuclear Spectroscopic Telescope Array (NuSTAR), and the Neil Gehrels Swift Observatory (Swift). These spectra are well fitted by a model comprising a disk, a weak corona, and a reflection component. We suggest that the reflection component is caused by disk self-irradiation, that is by photons emitted from the inner disk that return to the accretion disk surface as their trajectories are bent by the strong gravity field. In this scenario, the best-fitting parameters imply that the reflected flux represents more than half of the total flux. Using general relativistic ray-tracing simulations, we show that this scenario is viable when the disk becomes geometrically thick, with a funnel-like shape, as the accretion rate is near or above the Eddington limit. In the specific case of 4U 1543–47, an angle ≳45 deg between the disk surface and the equatorial plane can explain the required amount of self-irradiation. [ABSTRACT FROM AUTHOR]

We present a comprehensive timing analysis on the Be/X-ray binary pulsar RX J0440.9+4431 using observations from NICER and Insight - HXMT during the 2022–2023 outburst. The power density spectrum (PDS) of RX J0440.9+4431 exhibits typical aperiodic variability in X-ray flux across a wide frequency range. During a supercritical accretion state, we detect quasi-periodic oscillations (QPOs) at 0.2–0.5 Hz in the light curves of five pulses for RX J0440.9+4431. The observed QPOs manifest during flares, while the flares appear at the peaks of the pulse profiles on a time-scale of seconds and are primarily caused by an increase in hard photons. These flares can be explained by increased material ingestion in the accretion column at a fixed phase, primarily generating hard photons. Alternatively, an increase in accretion rate, independent of phase, may result in highly beamed hard photons within the accretion column, causing the flares. We argue the origin of QPOs to instabilities within the accretion flow. Additionally, we find that the break frequencies in the noise power spectra align well with |$\propto L_{\mathrm{x}}^{3 / 7}$| across three orders of magnitude in the luminosity, which points to a relatively strong magnetic field in RX J0440.9+4431, estimated to be ~1013 G. [ABSTRACT FROM AUTHOR]

RX J0440.9+4431, a Be/X-ray binary, had its brightest outburst in 2022 since its discovery, with a peak X-ray flux of 2.25 Crab (as recorded by Swift /BAT, 15–50 keV). We analyze the timing properties of this giant outburst using data from Insight -Hard X-ray Modulation Telescope and Neutron Star Interior Composition Exlporer , focusing on the evolution of the pulse profile and pulse fraction. We observe that when the luminosity reached around ~ |$3\times 10^{37}\ {\rm erg\ \rm s^{-1}}$|⁠ , a transition from double-peaked to single-peaked pulse profiles occurred across the energy range, with the peak of the low-energy profile aligning gradually with the peak of the high-energy profile. This change indicates a transition from subcritical to supercritical accretion. Additionally, we found a concave in the pulse fraction as a function of energy around 20–30 keV throughout the entire outburst period. Compared to the low luminosity, the concave becomes weaker in high luminosities, and overall, the pulse fraction is higher. We propose that this concave could be caused by the scattering of high-energy photons by the atmosphere of a neutron star, leading to a dilution of the pulse fraction. As the accretion reaches the supercritical state, the accretion column height increases, resulting in a larger direct component of strongly beamed X-ray flux, and an elevated pulse fraction. [ABSTRACT FROM AUTHOR]

MAXI J1816–195 is a newly discovered accreting millisecond X-ray pulsar that went outburst in 2022 June. Through timing analysis with Neutron star Interior Composition Explorer (NICER) and Nuclear Spectroscopic Telescope Array (NuSTAR) observations, we find a transient modulation at ~2.5 Hz during the decay period of MAXI J1816–195. The modulation is strongly correlated with a spectral hardening, and its fractional rms amplitude increases with energy. These results suggest that the modulation is likely to be produced in an unstable corona. In addition, the presence of the modulation during thermonuclear bursts indicates that it may originate from a disc-corona where the optical depth is likely the main factor affecting the modulation, rather than temperature. Moreover, we find significant reflection features in the spectra observed simultaneously by NICER and NuSTAR , including a relativistically broadened Fe-K line around 6–7 keV, and a Compton hump in the 10–30 keV energy band. The radius of the inner disc is constrained to be R in  = (1.04–1.23)  R ISCO based on reflection modeling of the broad-band spectra. Assuming that the inner disc is truncated at the magnetosphere radius, we estimate that the magnetic field strength is |$\le 4.67 \times 10^{8}\, \rm G$|⁠. [ABSTRACT FROM AUTHOR]

We present the results of a detailed timing and spectral analysis of the quasi-regular modulation (QRM) phenomenon in the black hole X-ray binary 4U 1630−47 during its 1998 outburst observed by the Rossi X-ray Timing Explorer (RXTE). We find that the ∼50–110 mHz QRM is flux dependent, and the QRM is detected with simultaneous low-frequency quasi-periodic oscillations (LFQPOs). According to the behaviour of the power density spectrum, we divide the observations into four groups. In the first group, namely behaviour A, LFQPOs are detected, but no mHz QRM. The second group, namely behaviour B, a QRM with frequency above ∼88 mHz is detected and the ∼5 and ∼7 Hz LFQPOs are almost overlapping. In the third group, namely behaviour C, the QRM frequency below ∼88 mHz is detected and the LFQPOs are significantly separated. In the fourth group, namely behaviour D, neither QRM nor LFQPOs are detected. We study the energy dependence of the fractional rms, centroid frequency, and phase lag of QRM and LFQPOs for behaviour B and C. We then study the evolution of QRM and find that the frequency of QRM increases with hardness, while its rms decreases with hardness. We also analyse the spectra of each observation, and find that the QRM rms of behaviour B has a positive correlation with |$F_{\rm power\ law}$| / |$F_{\rm total}$|⁠. Finally, we give our understanding for this mHz QRM phenomenon. [ABSTRACT FROM AUTHOR]

Using the observations of the high-energy detector of the Hard X-ray Modulation Telescope (Insight-HXMT) for Scorpius X-1 from 2017 to 2020, we search for hard X-ray tails in the X-ray spectra in ∼30–200 keV. The hard X-ray tails are found throughout the Z -track on the hardness–intensity diagram, and the detected hard X-ray tails become hard and weak from the horizontal branch (HB), through the normal branch (NB), to the flaring branch (FB). Comparing the hard X-ray spectra of Insight-HXMT between Cyg X-1 and Sco X-1, it is concluded that the hard X-ray spectrum of Cyg X-1 shows a high-energy cutoff, implying a hot corona in it, but the high-energy cutoff is not seen in the hard X-ray spectrum of Sco X-1. From fitting the broadband spectrum of Sco X-1 in ∼2–200 keV, it is proposed that the hard X-ray tails in the HB and NB can be explained by the overall Comptonization COMPTB model, suggesting that the hard X-ray tails could have resulted from the Comptonization of the photons from the neutron star (NS) surface by the thermal electrons in the region between the NS and the disk and the energetic electrons in the freefall toward the NS in the converging flow onto the NS. However, this model cannot be responsible for the hard X-ray tails in the FB. Further study on the FB hard X-ray tails is needed. [ABSTRACT FROM AUTHOR]

Highlights • The combustion behaviors of biomass and coal particles were studied. • The effects of AAEM species on biomass and coal combustion were compared. • Potassium shows the strongest catalytic effect in the entire combustion process. Abstract Alkali and alkaline earth metal (AAEM) species are the main components of the ash of biomass, and which would influence the combustion of biomass and coal during the co-firing process. The aim of this paper is to investigate the effects of potassium (K), sodium (Na), calcium (Ca), and magnesium (Mg) on the combustion characteristics of pine sawdust (PS) and bituminous coal (BC) by a single particle combustion method. The raw, ash-free and impregnated samples were prepared, and their combustion processes were recorded by a high speed camera. Based on the recorded flame images, the effects of K, Na, Ca and Mg on the combustion characteristics (ignition, volatiles combustion, char combustion) of PS and BC were analyzed. The results reveal that the demineralization treatment brings negative effects on the combustion of PS, which reflects in longer ignition delay time, volatiles and char burnout time, and lower combustion temperature, while the effects on the combustion of BC are opposite. The impregnated samples exhibit shorter ignition delay time, volatiles and char burnout time, and higher combustion temperature than the ash-free samples. In the entire combustion process of PS and BC, K exhibits the strongest promotion effect. When the concentration of K increases from 0 to 2 wt%, the ignition delay time of PS and BC decreases about 5.5 ms and 16.4 ms respectively, the volatiles combustion temperature increases about 41 °C and 77 °C respectively, and the char combustion temperature increases about 226 °C and 141 °C respectively. [ABSTRACT FROM AUTHOR]

We report the X-ray timing results of the black hole candidate MAXI J1820+070 during its 2018 outburst using the Hard X-ray Modulation Telescope (Insight-HXMT) and Neutron Star Interior Composition Explorer Mission (NICER) observations. Low-frequency quasi-periodic oscillations (LFQPOs) are detected in the low/hard state and the hard intermediate state, which lasted for ∼90 days. Thanks to the large effective area of Insight-HXMT at high energies and NICER at low energies, we are able to present the energy dependence of the LFQPO characteristics and phase lags from 0.2 to 200 keV, which has never been explored by previous missions. We find that the centroid frequency of the LFQPOs does not change significantly with energy, while the full width at half maximum and fractional rms show a complex evolution with energy. The LFQPO phase lags at high energies and low energies show consistent energy-dependence relations taking the ∼2 keV as reference. Our results suggest that the LFQPOs from high energy come from the LT precession of the relativistic jet, while the low-energy radiation is mainly from the perpendicular innermost regions of the accretion disk. [ABSTRACT FROM AUTHOR]

We report the evolution of the X-ray pulsations of EXO 2030+375 during its 2021 outburst using the observations from Insight -HXMT. Based on the accretion torque model, we study the correlation between the spin frequency derivatives and the luminosity. Pulsations can be detected in the energy band of 1–160 keV. The pulse profile evolves significantly with luminosity during the outburst, leading to that the whole outburst can be divided into several parts with different characteristics. The evolution of the pulse profile reveals the transition between the supercritical (fan-beam dominated) and the subcritical accretion (pencil-beam dominated) mode. From the accretion torque model and the critical luminosity model, based on a distance of 7.1 kpc, the inferred magnetic fields are (0.41 − 0.74) × 1012 and (3.48 − 3.96) × 1012 G, respectively, or based on a distance of 3.6 kpc, the estimated magnetic fields are (2.4 − 4.3) × 1013 and (0.98 − 1.11) × 1012 G, respectively. Two different sets of magnetic fields both support the presence of multipole magnetic fields of the neutron star. [ABSTRACT FROM AUTHOR]

We studied the transient Galactic black hole candidate MAXI J0637−430 with data from Insight-HXMT, Swift , and XMM–Newton. The broad-band X-ray observations from Insight-HXMT help us constrain the power-law component. MAXI J0637–430 is located at unusually high Galactic latitude; if it belongs to the Galactic thick disc, we suggest a most likely distance ≲7 kpc. Compared with other black hole transients, MAXI J0637–430 is also unusual for other reasons: a fast transition to the thermal dominant state at the start of the outburst; a low peak temperature and luminosity (we estimate them at ≈0.7 keV and ≲0.1 times Eddington, respectively); a short decline time-scale; a low soft-to-hard transition luminosity (≲0.01 times Eddington). We argue that such properties are consistent with a small binary separation, short binary period (P ∼ 2 h), and low-mass donor star (M 2 ∼ 0.2 M⊙). Moreover, spectral modelling shows that a single disc blackbody component is not a good fit to the thermal emission. Soft spectral residuals, and deviations from the standard |$L_{\rm disc} \propto T_{\rm in}^4$| relation, suggest the need for a second thermal component. We propose and discuss various scenarios for such component, in addition to those presented in previous studies of this source. For example, a gap in the accretion disc between a hotter inner ring near the innermost stable orbit, and a cooler outer disc. Another possibility is that the second thermal component is the thermal plasma emission from an ionized outflow. [ABSTRACT FROM AUTHOR]

We studied the 2018 outburst of the black hole transient H 1743 − 322 with a series of Insight-HXMT, NICER , and NuSTAR observations, covering the 1–120 keV band. With our broad-band X-ray spectral modelling, we confirm that the source remained in the low/hard state throughout the month-long outburst, although it became marginally softer at peak flux. We detected Type-C quasi-periodic oscillations (QPOs) and followed the evolution of their properties. The QPO frequency increased from ∼0.1 to ∼0.4 Hz during the rising phase of the outburst and decreased again in the decline. Continuum X-ray flux, power-law photon index, QPO frequency, and QPO root-mean-square amplitude were positively correlated. The QPO amplitude was slightly higher in the soft X-ray band (typical values of 12–16 per cent, compared with 8–10 per cent in the hard band). Our spectral-timing results shed light on the initial rising phase in the low/hard state, which has rarely been monitored with such high cadence, time resolution, and broad-band coverage. Combining spectral and timing properties, we find that 'failed' (hard state only) and 'successful' outbursts follow the same initial evolutionary track, although the former class of outburst never reaches the threshold for a transition to softer (thermally dominated) accretion regimes. [ABSTRACT FROM AUTHOR]

The High Energy (HE) X-ray telescope on board the Hard X-ray Modulation Telescope (Insight -HXMT) can serve as a wide field of view (FOV) gamma-ray monitor with high time resolution (μs) and large effective area (up to thousands cm2). 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. Fermi /GBM, 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 Insight -HXMT/HE data, our targeted search recovered 40 GRBs, which were detected by either Swift /BAT or Fermi /GBM but too weak to be found in our blind search. With this coherent search pipeline, the GRB detection sensitivity of 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 Insight -HXMT/HE data for electromagnetic counterparts of LIGO-Virgo GW events (including O2 and O3a runs). However, we did not find any significant burst associated with GW events. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this paper, we presented a detailed timing analysis of a prominent outburst of 4U 0115+63 detected by Insight -HXMT in 2017 August. The spin period of the neutron star was determined to be 3.613 98 ± 0.000 02 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 |$0.048^\circ \pm 0.003^\circ \rm \, yr^{-1}$|⁠. The light curves are folded to sketch the pulse profiles in different energy ranges. A multipeak structure in 1–10 keV is clearly illustrated. We introduced wavelet analysis into our data analysis procedures to study quasi-periodic oscillation (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 of ∼10 mHz. In addition, the X-ray light curves showed multiple QPOs in the period of ∼16–32 and ∼67–200 s. We found that the ∼100 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 ∼67–200 s QPO is drifting frequently while that of ∼16–32 s QPO is scarcely drifting. The dissipation of oscillations from high energy to low energy was also observed. These features of QPOs in 4U 0115+63 provide a new challenge to our understanding of their physical origins. [ABSTRACT FROM AUTHOR]

We report the timing and spectral analyses of the type-II X-ray bursts from the rapid burster (MXB 1730–335) observed by the Hard X-ray Modulation Telescope (Insight-HXMT) and Swift/X-Ray Telescope (XRT). By stacking the long-duration bursts, we find for the first time that the hard X-rays are lagging behind the soft X-rays by 3 s. However, such a lag is not visible for the short-duration bursts, probably because of the poor statistics. For all bursts the energy spectrum is found to be nonthermal, thanks to the broadband coverage of Insight-HXMT. These findings provide new insights into the type-II bursts and require a temporally visible corona for possible interpretation. [ABSTRACT FROM AUTHOR]

We present a detailed spectral-timing analysis of the Kilohertz quasiperiodic oscillations (kHz QPOs) in Sco X-1 using the data of the Rossi X-ray Timing Explorer (RXTE) and the Hard X-ray Modulation Telescope (Insight-HXMT). The energy band with detectable kHz QPOs is studied for the first time: on the horizontal branch, it is ∼6.89–24.01 and ∼8.68–21.78 keV for the upper and lower kHz QPOs, respectively, detected by the RXTE, and ∼9–27.5 keV for the upper kHz QPOs by the Insight-HXMT; on the lower normal branch, the energy band is narrower. The fractional root mean square (rms) of the kHz QPOs increases with energy at a lower energy, reaches a plateau at about 16 and 20 keV for the lower and upper peaks, and then levels off though with a large uncertainty. The simulation of the deadtime effect of RXTE/PCA shows that the deadtime does not affect much the search of the kHz QPOs but makes the rms amplitude underestimated. No significant QPO is detected below ∼6 keV as shown by the RXTE data, implying that the kHz QPOs do not originate from the blackbody emission of the accretion disk and neutron star surface. In addition, with the combined analysis of the energy spectra and the absolute rms spectra of kHz QPOs, we suggest that the kHz QPOs in Sco X-1 originate from the Comptonization of the inner part of the transition layer, where the rotation sets the frequency and the inward bulk motion makes the spectrum harder. [ABSTRACT FROM AUTHOR]

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 Kα, Kβ, and Ni Kα 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 (Kα and Kβ), we infer the accretion material is in a low ionization 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 Kα lines throughout the orbit, which suggests that the accretion material near the neutron star is spherically distributed. [ABSTRACT FROM AUTHOR]

We performed the broadband (1–100 keV) spectral analysis of the first Galactic Be ultraluminous X-ray pulsar (BeULX) Swift J0243.6+6124 observed by Insight-HXMT during the 2017−2018 outburst. The results show spectral transitions at two typical luminosities, roughly consistently with those reported previously via pure timing analysis. We find that the spectrum evolves and becomes softer and has higher cutoff energies until the luminosity reaches L1 (∼1.5 × 1038 erg s−1). Afterwards the spectrum becomes harder with lower cutoff energies until the luminosity increases to L2 (∼4.4 × 1038 erg s−1), around which the second spectral transition occurs. Beyond L2, the spectrum softens again and has larger cutoff energies. Similar behaviors were observed previously in other high-mass X-ray binary systems (HMXBs), especially for the second transition at higher luminosities, which is believed to have a correlation with the magnetic field of the harbored neutron star. Accordingly, we speculate that Swift J0243.6+6124 owns a neutron star with magnetic field strength >1013 G. The spectral transition at around L1 of Swift J0243.6+6124 is first observed thoroughly for any HMXB outburst characterized by strong evolution of the thermal component: the temperature of the blackbody drops sharply accompanied by a sudden increase of the blackbody radius. These spectral transitions can in principle be understood in a general scenario of balancing the emission patterns between the pencil and the fan beams at the magnetic pole, for which the extreme brightness of Swift J0243.6+6124 may provide an almost unique lab to probe the details. [ABSTRACT FROM AUTHOR]

Context. A link has finally been established between magnetars and fast radio burst (FRB) sources. Within this context, a major issue that remains unresolved pertains to whether sources of extragalactic FRBs exhibit X/γ-ray outbursts and whether this is correlated with radio activity. If so, the subsequent goal is to identify these sources. Aims. We aim to constrain possible X/γ-ray burst activity from one of the nearest extragalactic FRB sources currently known. This is to be done over a broad energy range by looking for bursts over a range of timescales and energies that are compatible with those of powerful flares from extragalactic magnetars. Methods. We followed up on the observation of the as-yet nearest extragalactic FRB source, located at a mere 149 Mpc distance, namely, the periodic repeater FRB 180916.J0158+65. This took place during the active phase between 4 and 7 February 2020, using the Insight–Hard X-ray Modulation Telescope (Insight–HXMT). By taking advantage of the combination of broad-band wavelengths, a large effective area, and several independent detectors at our disposal, we searched for bursts over a set of timescales from 1 ms to 1.024 s with a sensitive algorithm that had been previously 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 a range of different energy spectra. Results. We constrain the possible occurrence of flares in the 1−100 keV energy band to E <  1046 erg for durations Δ t <  0.1 s over several tens of ks exposure. Conclusions. We can rule out the occurrence of giant flares similar to the ones that were observed in the few cases of Galactic magnetars. The absence of reported radio activity during our observations prevents us from making any determinations regarding the possibility of simultaneous high-energy emission. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 ∼1.5. The pulse-profile shape during the flares can be significantly different from 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 supercritical 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. [ABSTRACT FROM AUTHOR]

We report on analysis of observations of the bright transient X-ray pulsar (XRP) Swift  J0243.6+6124 obtained during its 2017–2018 giant outburst with Insight-HXMT, NuSTAR , and 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 disc to a radiation pressure dominated 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 supercritical 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, 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. [ABSTRACT FROM AUTHOR]

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 0.2–10.0 keV switches from double to triple peaks at ∼2.5 |$\rm \times 10^{37}{\it D}_{10}^2\ erg\ s^{-1}$| and from triple to quadruple peaks at ∼7 |$\rm \times 10^{37}{\it D}_{10}^2\ erg\ s^{-1}$|⁠. The profile at high energies (25–100 keV) 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 supercritical 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 ∼7 × 1012 G. [ABSTRACT FROM AUTHOR]

Background: Zinc finger proteins (ZFPs) play an important role in regulating plant responses to abiotic stress. However, little is known about the function of LSD1-like-type ZFP in saline-alkaline (SA) stress resistance of rice. In this study, OsLOL5 (GenBank No. AJ620677), containing two LSD1-like-type C2C2 domains, was isolated and analyzed its protection roles in transgenic plants and yeast. OsLOL5 was located in the nucleus as evidenced by the bombardment of onion epidermal cells. Results: OsLOL5 expression significantly increased in rice leaves and roots under 150 mmol L-1 NaCl, 30 mM NaHCO3, and 10 mmol L-1 H2O2 treatment, respectively. Overexpression of OsLOL5 in yeast resulted in SA tolerance at significant level. Transgenic Arabidopsis plants overexpressing OsLOL5 grew well in the presence ofboth NaCl and NaHCO3 treatments, whereas wild-type plants exhibited chlorosis, stunted growth phenotype, and even death. SA stress caused significant changes in the malondialdehyde (MDA) contents in non-transgenic plants compared with those in transgenic lines. Transgenic rice overexpressing OsLOL5 exhibited stronger resistance than NT under NaHCO3 treatment, as demonstrated by its greater shoot length, and fresh weight. The genes associated with oxidative stress, such as OsAPX2, OsCAT, OsCu/Zn-SOD, and OsRGRC2, were significantly upregulated in OsLOL5- overexpressing rice. The results suggested that OsLOL5 improved SA tolerance in plants, and regulated oxidative and salinity stress retardation via the active oxygen detoxification pathway. Conclusions: The yeast INVScI bacterium grew significantly better than the control strain under NaCl, NaHCO3, and H2O2 treatments. These findings illustrated that OsLOL5 overexpression enhanced yeast resistance for SA stress through active oxygen species. The present study showed that the OsLOL5 genes involved in the ROS signaling pathways may combine with the model plant Arabidopsis and rice in LDS1-type ZFP by ROS signaling pathways that regulate cell necrosis. We speculated that the OsLOL5 active oxygen scavenging system may have coordinating roles. The present study further revealed that OsLOL5 ZFP could regulate oxidative stress function, but could also provide a basis for saltresistant rice strains. [ABSTRACT FROM AUTHOR]

Studies have shown a few cerebral metabolites modified by cocaine in brain regions; however, endogenous metabolic profiling has been lacking. Ex vivo 1 H NMR (hydrogen-1 nuclear magnetic resonance) spectroscopy-based metabonomic approach coupled with partial least squares was applied to investigate the changes of cerebral metabolites in nucleus accumbens (NAc) and striatum of rats subjected to cocaine treatment. Our results showed that both single and repeated cocaine treatment can induce significant changes in a couple of cerebral metabolites. The increase of neurotransmitters glutamate and gamma-amino butyric acid (GABA) were observed in NAc and striatum from the rats repeatedly treated with cocaine. Creatine and taurine increased in NAc whereas taurine increased and creatine decreased in striatum after repeated cocaine treatment. Elevation of N -acetylaspartate in NAc and striatum and decrease of lactate in striatum were observed, which may reflect the mitochondria dysregulation caused by cocaine; moreover, alterations of choline, phosphocholine and glycerol in NAc and striatum could be related to membrane disruption. Moreover, groups of rats with and without conditioned place preference (CPP) apparatus are presenting difference in metabolites. Collectively, our results provide the first evidence of metabonomic profiling of NAc and striatum in response to cocaine, exhibiting a regionally-specific alteration patterns. We find that repeated cocaine administration leads to significant metabolite alterations, which are involved in neurotransmitter disturbance, oxidative stress, mitochondria dysregulation and membrane disruption in brain. [ABSTRACT FROM AUTHOR]

Summary. The aim of this study was to further investigate the prevalence of infection and genotype of hepatitis E virus (HEV) among different species of animals, people whose works are related to pigs and the general population in the suburb of Beijing, China. Serum and faecal samples were collected from 10 animal species and humans. Anti-HEV was detected by enzyme immunoassays (EIA); HEV RNA was amplified by reverse transcription-nested polymerase chain reaction (RT-nPCR) method. PCR products were cloned and sequenced. The isolated swine HEV sequences were analysed phylogenetically. The positive rates of serum anti-HEV in swine, cattle, milk cow, horse, sheep, donkey, dog, duck, chicken, pig farm workers and slaughterhouse workers, and general population were 81.17% (802/988), 25.29% (66/261), 14.87% (40/269), 14.29% (40/280), 9.30% (53/514), 0 (0/25), 0 (0/20), 2.53% (8/316), 3.03% (7/231), 58.73% (37/63), 35.87% (66/184) and 20.06% (538/2682), respectively. The anti-HEV prevalence in adult swine (≥6 months) and younger swine (≤3 months) was 91.49% (591/646) and 61.7% (211/342), respectively. The positive rate of HEV RNA in young swine faeces was 47.94% (93/194). All 93 isolates from the younger swine shared 87.8-100% nucleotide homology with each other and had identities of 75.6-78.9%, 73.9-76.1%, 76.4-80.6% and 83.1-95.0% with the corresponding regions of genotypes 1-4 HEV, respectively. Phylogenetic analysis showed that all HEV isolates belong to genotype 4, subgenotype 4d. These results suggest a potential risk of zoonotic transmission of HEV from younger swine to farmers who rear pigs. [ABSTRACT FROM AUTHOR]

Summary. A novel genotype of hepatitis E virus (HEV) isolated from rabbits is reported. The aim of this study was to confirm and further investigate the prevalence of the novel HEV genotype in rabbits in China. Sera and faecal samples were collected from farmed rex rabbits in Beijing, China. All serum samples were tested for anti-HEV antibody by EIA. Both the serum and the faecal samples were evaluated for detection of HEV RNA using a nested RT-PCR assay. The nucleotide sequences of rabbit HEV were then analysed, and sequence homology of rabbit HEV compared against human HEV genotypes 1-4, and avian HEV. Results: The prevalence of positive serum anti-HEV from rex rabbits was 54.62% (65/119). The detection rate of HEV RNA using ORF2 primers was 6.96% (8/115) amongst rabbit faecal samples. All eight amplicons shared 98.3-100% nucleotide homology with each other and had identities of 75.8-78.6%, 73.9-75.0%, 77.5-81.0%, 74.2-78.6% and 54.8-57.6% with the corresponding regions of genotypes 1-4 and avian HEV, respectively. Phylogenetic analysis showed that the eight sequences formed one individual branch and were on the same branch with GDC9 and GDC46, both of which were reported to be a novel genotype of HEV isolated from rabbits. The conclusion is that this study provides further information about HEV infecting rabbits, which may be a new animal host of HEV, as well as genetical evidence of a new mammalian genotype of HEV. [ABSTRACT FROM AUTHOR]

Past studies on the efficacy of participation in online cancer support groups have primarily focused on the role of expression in the accrual of health benefits for participants. Unfortunately, few steps have been taken to determine whether this observed effect arises solely from the internal mental processes underlying the act of expressing or, perhaps, owes something to a nuanced, multidimensional understanding of expression that includes reception of responses to what is expressed. To test for the multilayered effect, we attend to one of the key concepts in the online support community scholarship: empathy. Our findings suggest that it is a combination of empathy expression and reception that is crucial to attaining optimal benefits for cancer patients. Further, our finding supports the buffering hypothesis that empathic expression provides a salutary effect for patients who experienced a higher degree of concern associated with their cancer diagnosis and follow-up treatments. [ABSTRACT FROM AUTHOR]