Mergers of neutron stars are known to be associated with short γ-ray bursts
. If the neutron-star equation of state is sufficiently stiff (that is, the pressure increases sharply as the density ...increases), at least some such mergers will leave behind a supramassive or even a stable neutron star that spins rapidly with a strong magnetic field
(that is, a magnetar). Such a magnetar signature may have been observed in the form of the X-ray plateau that follows up to half of observed short γ-ray bursts
. However, it has been expected that some X-ray transients powered by binary neutron-star mergers may not be associated with a short γ-ray burst
. A fast X-ray transient (CDF-S XT1) was recently found to be associated with a faint host galaxy, the redshift of which is unknown
. Its X-ray and host-galaxy properties allow several possible explanations including a short γ-ray burst seen off-axis, a low-luminosity γ-ray burst at high redshift, or a tidal disruption event involving an intermediate-mass black hole and a white dwarf
. Here we report a second X-ray transient, CDF-S XT2, that is associated with a galaxy at redshift z = 0.738 (ref.
). The measured light curve is fully consistent with the X-ray transient being powered by a millisecond magnetar. More intriguingly, CDF-S XT2 lies in the outskirts of its star-forming host galaxy with a moderate offset from the galaxy centre, as short γ-ray bursts often do
. The estimated event-rate density of similar X-ray transients, when corrected to the local value, is consistent with the event-rate density of binary neutron-star mergers that is robustly inferred from the detection of the gravitational-wave event GW170817.
Abstract
The Kagome superconductors AV
3
Sb
5
(A = K, Rb, Cs) have received enormous attention due to their nontrivial topological electronic structure, anomalous physical properties and ...superconductivity. Unconventional charge density wave (CDW) has been detected in AV
3
Sb
5
. High-precision electronic structure determination is essential to understand its origin. Here we unveil electronic nature of the CDW phase in our high-resolution angle-resolved photoemission measurements on KV
3
Sb
5
. We have observed CDW-induced Fermi surface reconstruction and the associated band folding. The CDW-induced band splitting and the associated gap opening have been revealed at the boundary of the pristine and reconstructed Brillouin zones. The Fermi surface- and momentum-dependent CDW gap is measured and the strongly anisotropic CDW gap is observed for all the V-derived Fermi surface. In particular, we have observed signatures of the electron-phonon coupling in KV
3
Sb
5
. These results provide key insights in understanding the nature of the CDW state and its interplay with superconductivity in AV
3
Sb
5
superconductors.
A Nationwide Nitrogen Deposition Monitoring Network (NNDMN) containing 43 monitoring sites was established in China to measure gaseous NH3, NO2, and HNO3 and particulate NH4+ and NO3− in air and/or ...precipitation from 2010 to 2014. Wet/bulk deposition fluxes of Nr species were collected by precipitation gauge method and measured by continuous-flow analyzer; dry deposition fluxes were estimated using airborne concentration measurements and inferential models. Our observations reveal large spatial variations of atmospheric Nr concentrations and dry and wet/bulk Nr deposition. On a national basis, the annual average concentrations (1.3–47.0 μg N m−3) and dry plus wet/bulk deposition fluxes (2.9–83.3 kg N ha−1 yr−1) of inorganic Nr species are ranked by land use as urban > rural > background sites and by regions as north China > southeast China > southwest China > northeast China > northwest China > Tibetan Plateau, reflecting the impact of anthropogenic Nr emission. Average dry and wet/bulk N deposition fluxes were 20.6 ± 11.2 (mean ± standard deviation) and 19.3 ± 9.2 kg N ha−1 yr−1 across China, with reduced N deposition dominating both dry and wet/bulk deposition. Our results suggest atmospheric dry N deposition is equally important to wet/bulk N deposition at the national scale. Therefore, both deposition forms should be included when considering the impacts of N deposition on environment and ecosystem health.
Abstract
A nanohertz-frequency stochastic gravitational-wave background can potentially be detected through the precise timing of an array of millisecond pulsars. This background produces ...low-frequency noise in the pulse arrival times that would have a characteristic spectrum common to all pulsars and a well-defined spatial correlation. Recently the North American Nanohertz Observatory for Gravitational Waves collaboration (NANOGrav) found evidence for the common-spectrum component in their 12.5 yr data set. Here we report on a search for the background using the second data release of the Parkes Pulsar Timing Array. If we are forced to choose between the two NANOGrav models—one with a common-spectrum process and one without—we find strong support for the common-spectrum process. However, in this paper, we consider the possibility that the analysis suffers from model misspecification. In particular, we present simulated data sets that contain noise with distinctive spectra but show strong evidence for a common-spectrum process under the standard assumptions. The Parkes data show no significant evidence for, or against, the spatially correlated Hellings–Downs signature of the gravitational-wave background. Assuming we did observe the process underlying the spatially uncorrelated component of the background, we infer its amplitude to be
A
=
2.2
−
0.3
+
0.4
×
10
−
15
in units of gravitational-wave strain at a frequency of 1 yr
−1
. Extensions and combinations of existing and new data sets will improve the prospects of identifying spatial correlations that are necessary to claim a detection of the gravitational-wave background.
Objective
To assess the efficacy of metformin in megestrol acetate (MA)‐based fertility‐sparing treatment for patients with atypical endometrial hyperplasia (AEH) and endometrioid endometrial cancer ...(EEC).
Design
A randomised, single‐centre, open‐label, controlled trial conducted between October 2013 and December 2017.
Setting
Shanghai OBGYN Hospital of Fudan University, China.
Population
A total of 150 patients (18–45 years old) with primary AEH or well‐differentiated EEC were randomised into an MA group (n = 74) and an MA plus metformin group (n = 76).
Methods
Patients with AEH or EEC were firstly stratified, then randomised to receive MA (160 mg orally, daily) or MA (160 mg orally, daily) plus metformin (500 mg orally, three times a day).
Main outcomes and measures
The primary efficacy parameter was the cumulate complete response (CR) rate within 16 weeks of treatment (16w‐CR rate); the secondary efficacy parameters were 30w‐CR rate and adverse events.
Results
The 16w‐CR rate was higher in the metformin plus MA group than in the MA‐only group (34.3 versus 20.7%, odds ratio OR 2.0, 95% confidence interval CI 0.89–4.51, P = 0.09) but the difference was more significant in 102 AEH patients (39.6 versus 20.4%, OR 2.56, 95% CI 1.06–6.21, P = 0.04). This effect of metformin was also significant in non‐obese (51.4 versus 24.3%, OR 3.28, 95% CI 1.22–8.84, P = 0.02) and insulin‐sensitive (54.8 versus 28.6%, OR 3.04, 95% CI 1.03–8.97, P = 0.04) subgroups of AEH women. No significant result was found in secondary endpoints.
Conclusion
As a fertility‐sparing treatment, metformin plus MA was associated with a higher early CR rate compared with MA alone in AEH patients.
Tweetable
For AEH patients, metformin plus MA might be a better fertility‐sparing treatment to achieve a higher early CR rate compared with MA alone.
Tweetable
For AEH patients, metformin plus MA might be a better fertility‐sparing treatment to achieve higher early CR rate compared with MA alone.
We investigate the dependence of black hole accretion rate (BHAR) on host-galaxy star formation rate (SFR) and stellar mass (M*) in the CANDELS/GOODS-South field in the redshift range of . Our sample ...consists of galaxies, allowing us to probe galaxies with and/or . We use sample-mean BHAR to approximate long-term average BHAR. Our sample-mean BHARs are derived from the Chandra Deep Field-South 7 Ms observations, while the SFRs and M* have been estimated by the CANDELS team through spectral energy distribution fitting. The average BHAR is correlated positively with both SFR and M*, and the BHAR-SFR and BHAR-M* relations can both be described acceptably by linear models with a slope of unity. However, BHAR appears to be correlated more strongly with M* than SFR. This result indicates that M* is the primary host-galaxy property related to supermassive black hole (SMBH) growth, and the apparent BHAR-SFR relation is largely a secondary effect due to the star-forming main sequence. Among our sources, massive galaxies ( ) have significantly higher BHAR/SFR ratios than less massive galaxies, indicating that the former have higher SMBH fueling efficiency and/or higher SMBH occupation fraction than the latter. Our results can naturally explain the observed proportionality between and M* for local giant ellipticals and suggest that their is higher than that of local star-forming galaxies. Among local star-forming galaxies, massive systems might have higher compared to dwarfs.
An 8‐week feeding trial was conducted to evaluate the effects of dietary nucleotide (NT)‐rich yeast supplementation on growth, innate immunity and intestinal morphology in Pacific white shrimp ...(Litopenaeus vannamei). Four isonitrogenous and isolipidic practical diets were formulated to contain 0 (control), 10, 30 and 50 g/kg of NT‐rich yeast, respectively. A total of 480 shrimp with an average initial body weight of 1.86 ± 0.02 g were randomly allocated into four groups, with four replicates per group and 30 shrimp each replicate. The results indicated that shrimp fed the diet containing 50 g/kg NT‐rich yeast had significantly higher weight gain (WG), specific growth rate (SGR) and protein efficiency ratio (PER) than those fed the control diet, and the lowest feed conversion ratio (FCR) was observed in the shrimp fed the 50 g/kg NT‐rich yeast supplemental diet. However, there was no significant difference in survival among all treatments. The crude protein of whole shrimp in the 50 g/kg NT‐rich yeast group was higher than that in the control group. Total protein, triglyceride concentrations, the activities of aspartate aminotransferase and alanine aminotransferase in serum were significantly influenced by the dietary NT‐rich yeast supplementation. The activities of serum phenoloxidase (PO) and lysozyme (LZM) of shrimp fed the diet containing 50 g/kg NT‐rich yeast were higher than those in shrimp fed the other diets. Relative expressions of alp and lzm significantly upregulated in the 30 g/kg NT‐rich yeast group compared to the control group. The intestinal fold height and fold width in the 30 g/kg NT‐rich yeast group were significantly higher than those fed the control diet; and the highest microvillus height occurred in the shrimp fed the 50 g/kg NT‐rich yeast diet. In summary, dietary 30–50 g/kg NT‐rich yeast supplementation promotes growth performance, enhances innate immunity and improves intestinal morphology of Litopenaeus vannamei.
Owing to its conceptual simplicity and computational efficiency, the pseudopotential multiphase lattice Boltzmann (LB) model has attracted significant attention since its emergence. In this work, we ...aim to extend the pseudopotential LB model to simulate multiphase flows at large density ratio and relatively high Reynolds number. First, based on our recent work Q. Li, K. H. Luo, and X. J. Li, Phys. Rev. E 86, 016709 (2012), an improved forcing scheme is proposed for the multiple-relaxation-time pseudopotential LB model in order to achieve thermodynamic consistency and large density ratio in the model. Next, through investigating the effects of the parameter a in the Carnahan-Starling equation of state, we find that the interface thickness is approximately proportional to 1/√a. Using a smaller a will lead to a wider interface thickness, which can reduce the spurious currents and enhance the numerical stability of the pseudopotential model at large density ratio. Furthermore, it is found that a lower liquid viscosity can be gained in the pseudopotential model by increasing the kinematic viscosity ratio between the vapor and liquid phases. The improved pseudopotential LB model is numerically validated via the simulations of stationary droplet and droplet oscillation. Using the improved model as well as the above treatments, numerical simulations of droplet splashing on a thin liquid film are conducted at a density ratio in excess of 500 with Reynolds numbers ranging from 40 to 1000. The dynamics of droplet splashing is correctly reproduced and the predicted spread radius is found to obey the power law reported in the literature.
ABSTRACT We present measurements of the evolution of normal-galaxy X-ray emission from 0-7 using local galaxies and galaxy samples in the 6 Ms Chandra Deep Field-South (CDF-S) survey. The majority of ...the CDF-S galaxies are observed at rest-frame energies above 2 keV, where the emission is expected to be dominated by X-ray binary (XRB) populations; however, hot gas is expected to provide small contributions to the observed-frame 1 keV emission at z 1. We show that a single scaling relation between X-ray luminosity ( ) and star-formation rate (SFR) literature, is insufficient for characterizing the average X-ray emission at all redshifts. We establish that scaling relations involving not only SFR, but also stellar mass ( ) and redshift, provide significantly improved characterizations of the average X-ray emission from normal galaxy populations at 0-7. We further provide the first empirical constraints on the redshift evolution of X-ray emission from both low-mass XRB (LMXB) and high-mass XRB (HMXB) populations and their scalings with and SFR, respectively. We find (LMXB)/ and (HMXB)/SFR , and show that these relations are consistent with XRB population-synthesis model predictions, which attribute the increase in LMXB and HMXB scaling relations with redshift as being due to declining host galaxy stellar ages and metallicities, respectively. We discuss how emission from XRBs could provide an important source of heating to the intergalactic medium in the early universe, exceeding that of active galactic nuclei.
ABSTRACT We present X-ray source catalogs for the 7 Ms exposure of the Chandra Deep Field-South (CDF-S), which covers a total area of 484.2 arcmin2. Utilizing wavdetect for initial source detection ...and ACIS Extract for photometric extraction and significance assessment, we create a main source catalog containing 1008 sources that are detected in up to three X-ray bands: 0.5-7.0 keV, 0.5-2.0 keV, and 2-7 keV. A supplementary source catalog is also provided, including 47 lower-significance sources that have bright ( ) near-infrared counterparts. We identify multiwavelength counterparts for 992 (98.4%) of the main-catalog sources, and we collect redshifts for 986 of these sources, including 653 spectroscopic redshifts and 333 photometric redshifts. Based on the X-ray and multiwavelength properties, we identify 711 active galactic nuclei (AGNs) from the main-catalog sources. Compared to the previous 4 Ms CDF-S catalogs, 291 of the main-catalog sources are new detections. We have achieved unprecedented X-ray sensitivity with average flux limits over the central 1 arcmin2 region of 1.9 × 10−17, 6.4 × 10−18, and 2.7 × 10−17 erg cm−2 s−1 in the three X-ray bands, respectively. We provide cumulative number-count measurements observing, for the first time, that normal galaxies start to dominate the X-ray source population at the faintest 0.5-2.0 keV flux levels. The highest X-ray source density reaches 50,500 deg−2, and 47% 4% of these sources are AGNs ( 23,900 deg−2).
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