ABSTRACT
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.
To understand the impact of firework-burning (FW) particles on air quality and human health during the winter haze period, 39 elements, 10 water-soluble ions and 8 fractions of carbonaceous species ...in atmospheric PM2.5 in Nanjing were investigated during the 2014 Chinese Spring Festival (SF). Serious regional haze pollution persisted throughout the entire sampling period, with PM2.5 averaging at 113 plus or minus 69 mu g m-3 and visibility at 4.8 plus or minus 3.2 km. The holiday effect led to almost all the chemical species decreasing during the SF, except for Al, K, Ba and Sr which were related to FW. The source contributions of coal combustion, vehicle emission and road dust decreased dramatically, whereas FW contributed to about half of the PM2.5 during the SF period. The intensive emission of FW particles on New Year's Eve accounted for 60.1% of the PM2.5. Fireworks also obviously modified the chemical compositions of PM2.5, with 39.3% contributed by increased organic matter, followed by steadily increased loadings of secondary inorganic ions. The aging processes of the FW particles lasted for about 4 days reflected by the variations of Ba, Sr, NH super(+) sub(4), NO super(-) sub(3), SO sub(4) super(2-) and K super(+), characterized by heterogeneous reactions of SO sub(2) and NO sub(x) on crustal materials directly from FW, the replacement of Cl super(-) by NO super(-) sub(3) and SO sub(4) super(2-), coating of NO super(-) sub(3) and SO sub(4) super(2-) on soot, formation of secondary organic aerosols and metal-catalyzed formation of NO super(-) sub(3) and SO sub(4) super(2-) at higher relative humidity. During aging, the main contributors to the extinction coefficient shifted from elemental carbon and organic matter to ammonium sulfate. The particles raised higher cancer risk of 1.62 x 10 super(-6) by heavy metals (especially for Cd and As). This study provided detailed composition data and first comprehensive analysis of the aging processes of FW particles during the serious haze pollution period and their potential impact on human health.
The nodal-line semimetals have attracted immense interest due to the unique electronic structures such as the linear dispersion and the vanishing density of states as the Fermi energy approaching the ...nodes. Here, we report temperature-dependent transport and scanning tunneling microscopy (spectroscopy) STM(S) measurements on nodal-line semimetal ZrSiSe. Our experimental results and theoretical analyses consistently demonstrate that the temperature induces Lifshitz transitions at 80 and 106 K in ZrSiSe, which results in the transport anomalies at the same temperatures. More strikingly, we observe a V-shaped dip structure around Fermi energy from the STS spectrum at low temperature, which can be attributed to co-effect of the spin-orbit coupling and excitonic instability. Our observations indicate the correlation interaction may play an important role in ZrSiSe, which owns the quasi-two-dimensional electronic structures.
We report observations of gamma-ray emissions with energies in the 100-TeV energy region from the Cygnus region in our Galaxy. Two sources are significantly detected in the directions of the Cygnus ...OB1 and OB2 associations. Based on their positional coincidences, we associate one with a pulsar PSR J2032 + 4127 and the other mainly with a pulsar wind nebula PWN G75.2 + 0.1, with the pulsar moving away from its original birthplace situated around the centroid of the observed gamma-ray emission. This work would stimulate further studies of particle acceleration mechanisms at these gamma-ray sources.
We theoretically and numerically analyze thermal invisibility based on the concept of scattering cancellation and mantle cloaking. We show that a small object can be made completely invisible to heat ...diffusion waves, by tailoring the heat conductivity of the spherical shell enclosing the object. This means that the thermal scattering from the object is suppressed, and the heat flow outside the object and the cloak made of these spherical shells behaves as if the object is not present. Thermal invisibility may open new vistas in hiding hot spots in infrared thermography, military furtivity, and electronics heating reduction.
Postdental procedure bacteremia is common and troublesome. The comparative efficacy of multiple prophylactic interventions is unclear. We compared the efficacy of interventions for the prevention of ...postdental procedure bacteremia. We conducted a review of ClinicalKey, Cochrane CENTRAL, Embase, ProQuest, PubMed, ScienceDirect, Web of Science, and ClinicalTrials.gov from inception to December 4, 2018. Randomized controlled trials that evaluated prophylactic interventions for the prevention of postdental procedure bacteremia were eligible. The primary outcome was the incidence of postdental procedure bacteremia. A total of 24 trials were included with 2,147 participants. Our network meta-analysis demonstrated that intravenous administration of 1,000/200 mg of amoxicillin/clavulanate provided the least incidence of postdental procedure bacteremia among all the prophylactic interventions (odds ratio = 0.03, 95% CI = 0.00 to 0.63) as compared with the placebo/controls. Oral 3 g of amoxicillin had the least incidence of postdental procedure bacteremia among all oral or topical forms of prophylactic interventions (odds ratio = 0.10, 95% CI = 0.02 to 0.44) as compared with the placebo/controls. No serious adverse events, such as anaphylactic shock, mortality, and the development of antibiotic-resistant bacteria, were reported. None of the included subjects were of high risk of infectious endocarditis. Our network meta-analysis demonstrates that intravenous amoxicillin/clavulanate and oral amoxicillin might be the best prophylactic interventions in preventing postdental procedure bacteremia among all the oral/topical forms of interventions for the overall populations.
We present simple stellar population models based on the empirical X-shooter Spectral Library (XSL) from near-ultraviolet (NUV) to near-infrared (NIR) wavelengths. The unmatched characteristics of ...the relatively high resolution and extended wavelength coverage (350–2480 nm,
R
∼ 10 000) of the XSL population models bring us closer to bridging optical and NIR studies of intermediate-age and old stellar populations. It is now common to find good agreement between observed and predicted NUV and optical properties of stellar clusters due to our good understanding of the main-sequence and early giant phases of stars. However, NIR spectra of intermediate-age and old stellar populations are sensitive to cool K and M giants. The asymptotic giant branch, especially the thermally pulsing asymptotic giant branch, shapes the NIR spectra of 0.5–2 Gyr old stellar populations; the tip of the red giant branch defines the NIR spectra of older populations. We therefore construct sequences of the average spectra of static giants, variable O-rich giants, and C-rich giants to be included in the models separately. The models span the metallicity range −2.2 < Fe/H < +0.2 and ages above 50 Myr, a broader range in the NIR than in other models based on empirical spectral libraries. We focus on the behaviour of colours and absorption-line indices as a function of age and metallicity. Our models can reproduce the integrated optical colours of the Coma cluster galaxies at the same level as other semi-empirical models found in the literature. In the NIR, there are notable differences between the colours of the models and Coma cluster galaxies. Furthermore, the XSL models expand the range of predicted values of NIR indices compared to other models based on empirical libraries. Our models make it possible to perform in-depth studies of colours and spectral features consistently throughout the optical and the NIR range to clarify the role of evolved cool stars in stellar populations.
Summary
The role of protein intake in bone has been controversial. Our case-control study among Chinese elderly concluded that a higher consumption of protein, even substituted for fat, is associated ...with lowered hip fracture risk. Differences in protein sources, amino acids composition, gender, and calcium sufficiency may explain the inconsistency.
Purpose
The aim of the study was to investigate the association of dietary protein intakes with hip fracture risk among Chinese elderly.
Methods
This was a 1:1 age and sex matched cross-sectional study of case-control design among 1070 pairs of elderly Chinese people aged 55 to 80 years. Patients who were newly diagnosed (within 2-week) hip fracture by X-ray were recruited from four hospitals in Guangdong Province of China. Dietary intakes were evaluated by a validated food frequency questionnaire for total protein, protein from different sources, amino acids profiles, and estimated renal acid load in diet.
Results
Daily average intakes of total protein were 58.1±27.0 (women) and 65.7±31.8 (men) g/d for cases, and 66.8±21.5 (women) and 72.1±24.4 (men) for controls (
p
<0.001). Multivariable regression indicated that, compared with the lowest quartile, the highest quartile of consumption of energy adjusted total protein OR: 0.360 (0.206~0.630) for women and 0.381 (0.153~0.949) for men and animal protein 0.326 (0.183, 0.560) for women and 0.335 (0.136~0.828) for men was significantly associated with the lowered risk of hip fracture in a dose-response manner (all
p
for trend <0.05). A significant hip fracture risk reduction was observed in women with higher intakes of sulfur amino acids OR: 0.464 (0.286~0.753) and aromatic amino acids 0.537 (0.326~0.884) but not in men. Subgroup analysis suggested that these associations were more evident in elderly with lower body mass index and dietary calcium intake less than 400 mg/d.
Conclusions
A higher level of protein intake, even substituted for fat, is associated with lowered hip fracture risk.
Treatment with effective antibiotics is one important strategy for syphilis control in China. This study aimed to evaluate the prevalence of azithromycin resistance to T. pallidum in China. A ...cross-sectional study was conducted among 391 patients with early syphilis recruited from STD clinics in eight cities during October 2008 and October 2011. The swabs were obtained from the moist lesions of the participating patients. A touchdown/nested PCR of the 23S ribosomal RNA (rRNA) gene was performed on DNA samples extracted from these specimens. The presence or absence of the A2058G point mutation, conferring resistance to azithromycin, was determined by restriction enzyme digestion analysis of the PCR amplicon by MboII. Two hundred and eleven patients with primary or secondary syphilis were found to have T. pallidum DNA in their moist lesions by PCR assays. The A2058G mutation was present in 91.9% (194/211, 95% CI, 87.2–95.1%) of these patients, with no significant differences noted between patients from the eastern part (93.8%), southern part (88.6%) and northern part (95.2%) of China (v2 = 2.303, p 0.316). Compared with patients who had not taken macrolides in previous years before study entry, the patients who had taken the antibiotics had a significantly higher prevalence of azithromycin resistance (97.0% vs. 62.5%), with an odds ratio of 19.65 (95% CI, 5.77–66.93). It can be concluded that prevalence of azithromycin resistance is substantial in China and consequently that the macrolides should not be used as a treatment option for early or incubating syphilis in China.
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