Accurate determination of stellar atmospheric parameters and elemental abundances is crucial for Galactic archaeology via large-scale spectroscopic surveys. In this paper, we estimate stellar ...atmospheric parameters -- effective temperature T sub( eff), surface gravity log g and metallicity Fe/H, absolute magnitudes M sub( V) and M sub( Ks), ...-element to metal (and iron) abundance ratio .../M (and .../Fe), as well as carbon and nitrogen abundances C/H and N/H from the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) spectra with a multivariate regression method based on kernel-based principal component analysis, using stars in common with other surveys (Hipparcos, Kepler, Apache Point Observatory Galactic Evolution Experiment) as training data sets. Both internal and external examinations indicate that given a spectral signal-to-noise ratio (SNR) better than 50, our method is capable of delivering stellar parameters with a precision of ~100 K for T sub( eff), ~0.1 dex for log g, 0.3-0.4 mag for M sub( V) and M sub( Ks), 0.1 dex for Fe/H, C/H and N/H, and better than 0.05 dex for .../M (.../Fe). The results are satisfactory even for a spectral SNR of 20. The work presents first determinations of C/H and N/H abundances from a vast data set of LAMOST, and, to our knowledge, the first reported implementation of absolute magnitude estimation directly based on a vast data set of observed spectra. The derived stellar parameters for millions of stars from the LAMOST surveys will be publicly available in the form of value-added catalogues. (ProQuest: ... denotes formulae/symbols omitted.)
Abstract
We present the second release of value-added catalogues of the LAMOST Spectroscopic Survey of the Galactic Anticentre (LSS-GAC DR2). The catalogues present values of radial velocity Vr, ...atmospheric parameters – effective temperature Teff, surface gravity log g, metallicity Fe/H, α-element to iron (metal) abundance ratio α/Fe (α/M), elemental abundances C/H and N/H and absolute magnitudes MV and $M_{K_{\rm s}}$ deduced from 1.8 million spectra of 1.4 million unique stars targeted by the LSS-GAC since 2011 September until 2014 June. The catalogues also give values of interstellar reddening, distance and orbital parameters determined with a variety of techniques, as well as proper motions and multiband photometry from the far-UV to the mid-IR collected from the literature and various surveys. Accuracies of radial velocities reach 5 km s−1 for the late-type stars, and those of distance estimates range between 10 and 30 per cent, depending on the spectral signal-to-noise ratios. Precisions of Fe/H, C/H and N/H estimates reach 0.1 dex, and those of α/Fe and α/M reach 0.05 dex. The large number of stars, the contiguous sky coverage, the simple yet non-trivial target selection function and the robust estimates of stellar radial velocities and atmospheric parameters, distances and elemental abundances make the catalogues a valuable data set to study the structure and evolution of the Galaxy, especially the solar-neighbourhood and the outer disc.
To explore the characteristics of Helicobacter pylori resistance in China and the association between antibiotic resistance and several clinical factors.
H. pylori strains were collected from ...patients in 13 provinces or cities in China between 2010 and 2016. Demographic data including type of disease, geographic area, age, gender and isolation year were collected to analyse their association with antibiotic resistance. Antibiotic resistance was detected using the Etest test and the Kirby-Bauer disc diffusion method.
H. pylori were successfully cultured from 1117 patients. The prevalence of metronidazole, clarithromycin (CLA), azithromycin, levofloxacin (LEV), moxifloxacin, amoxicillin (AMO), tetracycline and rifampicin resistance was 78.2, 22.1, 23.3, 19.2, 17.2, 3.4, 1.9 and 1.5%, respectively. No resistance to furazolidone was observed. The resistance rates to LEV and moxifloxacin were higher in strains isolated from patients with gastritis compared to those with duodenal ulcer and among women. Compared to patients ≥40 years old, younger patients exhibited lower resistance rates to CLA, azithromycin, LEV and moxifloxacin. The resistance rates to CLA and AMO were higher in strains isolated more recently, and we also found that the prevalence of resistance to metronidazole, CLA, azithromycin and AMO were significantly different among different regions of China.
The resistance rates to metronidazole, CLA and LEV were high in China. Patient age, gender, disease and location were associated with the resistance of H. pylori to some antibiotics. Furazolidone, AMO and tetracycline are better choices for H. pylori treatment in China.
There has been considerable recent interest in the genetic, biological and epidemiological basis of mammographic density (MD), and the search for causative links between MD and breast cancer (BC) ...risk. This report will critically review the current literature on MD and summarize the current evidence for its association with BC. Keywords ‘mammographic dens*’, ‘dense mammary tissue’ or ‘percent dens*’ were used to search the existing literature in English on PubMed and Medline. All reports were critically analyzed. The data were assigned to one of the following aspects of MD: general association with BC, its relationship with the breast hormonal milieu, the cellular basis of MD, the generic variations of MD, and its significance in the clinical setting. MD adjusted for age, and BMI is associated with increased risk of BC diagnosis, advanced tumour stage at diagnosis and increased risk of both local recurrence and second primary cancers. The MD measures that predict BC risk have high heritability, and to date several genetic markers associated with BC risk have been found to also be associated with these MD risk predictors. Change in MD could be a predictor of the extent of chemoprevention with tamoxifen. Although the biological and genetic pathways that determine and perhaps modulate MD remain largely unresolved, significant inroads are being made into the understanding of MD, which may lead to benefits in clinical screening, assessment and treatment strategies. This review provides a timely update on the current understanding of MD’s association with BC risk.
Micro-arc oxidation (MAO) of AZ31B magnesium alloys was studied in alkaline silicate solutions at constant applied current densities. The microstructure, phase composition and elemental distribution ...of ceramic coatings were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDX). There are two inflections in the voltage–time response, three regions were identifiable and each of the regions was almost linear. The pores with different shapes distributed all over the coating surface, the number of the pores was decreasing, while the diameter was apparently increasing with prolonged MAO treatment time. There were also cracks on the coating surface, resulting from the rapid solidification of the molten oxide. The ceramic coating was comprised of two layers, an outer loose layer and an inner dense layer. The ceramic coating was mainly composed of forsterite phase Mg
2SiO
4 and MgO; the formation of MgO was similar to conversional anodizing technology, while formation of Mg
2SiO
4 was attributed to a high temperature phase transformation reaction. Presence of Si and O indicated that the electrolyte components had intensively incorporated into coatings.
Aim
To examine the association between depression and impaired glucose regulation, newly diagnosed diabetes and previously diagnosed diabetes in middle‐aged and elderly Chinese people, and whether ...depression was associated with different treatment regimens or durations of diabetes.
Methods
A cross‐sectional study was performed among 229 047 adults living in the community aged ≥ 40 years from 25 centres in China. The self‐reported depression rating scale Patient Health Questionnaire 9 (PHQ–9) was used to diagnose probable and sub‐threshold depression. Glucose metabolism status was determined according to World Health Organization 1999 diagnostic criteria.
Results
The numbers of participants with normal glucose regulation, impaired glucose regulation, newly diagnosed diabetes and previously diagnosed diabetes were 120 458, 59 512, 24 826 and 24 251, respectively. The prevalence of sub‐threshold depression in the total sample of participants was 4.8% (4.8%, 4.8%, 4.4% and 5.6% from normal glucose regulation to previously diagnosed diabetes, respectively), and the prevalence of probable depression was 1.1% (1.1%, 1.0%, 0.9% and 1.8% from normal glucose regulation to previously diagnosed diabetes, respectively). Compared with participants with normal glucose regulation, those with previously diagnosed diabetes had increased odds of probable depression odds ratio (OR) = 1.61, 95% confidence interval (CI) 1.39–1.87 and sub‐threshold depression (OR = 1.14, 95% CI 1.06–1.24), after adjustment for multiple confounding factors. Newly diagnosed diabetes or impaired glucose regulation was not associated with depression. Among those with previously diagnosed diabetes, insulin treatment was associated with greater odds of depression compared with no treatment or oral anti‐diabetic medicine.
Conclusion
Previously diagnosed diabetes, but not newly diagnosed diabetes or impaired glucose regulation, was associated with a higher prevalence of depression. Patients receiving insulin were more likely to have depression than those not receiving treatment or being treated with oral anti‐diabetic medicine.
What's new?
Using a nationwide sample of middle‐aged and elderly Chinese people, we showed that patients with previously diagnosed diabetes had a higher prevalence of depression, compared with those with normal glucose regulation. Newly diagnosed diabetes or impaired glucose regulation were not associated with depression.
Patients with diabetes treated with insulin had greater odds of suffering from depression than those who were treated with oral medicine or were untreated. Duration of diabetes was not associated with depression, after accounting for the role of different treatments.
Calcium titanate (CaTiO
3
) nanoparticles with different average sizes were prepared by a polyacrylamide gel route, where the particle size was tailored by using different chelating agents. Scanning ...electron microscope observation shows that the samples prepared by using the chelating agents EDTA, acetic acid, tartaric acid, and citric acid have an average particle size of 25, 33, 36, and 55 nm, respectively. All the particles are regularly shaped like spheres. The bandgap energy of the four samples is measured to be 3.66–3.59 eV by ultraviolet (UV)–visible diffuse reflectance spectroscopy. The photocatalytic activity of the prepared CaTiO
3
samples was evaluated by the degradation of methyl orange under 254 nm UV irradiation, revealing that they exhibit a good photocatalytic activity. Hydroxyl radicals are revealed, by the photoluminescence technique using terephthalic acid as a probe molecule, to be produced on the irradiated CaTiO
3
nanoparticles and suggested to be the primary active species toward the dye degradation.
Fourteen isolates of Toxoplamsa gondii were isolated from cats from 4 different geographic provinces (Anhui, Hubei, Shanxi and Guangdong) in China and their genetic diversity with 8 nuclear loci ...SAG2, SAG3, BTUB, GRA6, L358, PK1, c22-8, c29-2, and an apicoplast locus Apico, was analysed by restriction fragment length polymorphisms (RFLPs). Two genotypes from these 14 isolates were identified but none of them belongs to the typical genetic types (types I, II and III). It is unexpected that such high similarity was observed in these 14 isolates although their original regions are significantly distant. Our results strongly indicate that the three traditional clonal lineages of types I, II and III of this parasite may not be preponderant in China. In addition, our results show that the genotypes of T. gondii in China may be highly clonal with atypical genotypes and higher virulence.
ABSTRACT
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.
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
< 10
46
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.
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