Atypical radio pulsations from magnetar SGR 1935+2154

Magnetars are neutron stars with extremely strong magnetic fields, frequently powering high-energy activity in X-rays. Pulsed radio emission following some X-ray outbursts have been detected, albeit its physical origin is unclear. It has long been speculated that the origin of magnetars' radio signals is different from those from canonical pulsars, although convincing evidence is still lacking. Five months after magnetar SGR 1935+2154's X-ray outburst and its associated Fast Radio Burst (FRB) 20200428, a radio pulsar phase was discovered. Here we report the discovery of X-ray spectral hardening associated with the emergence of periodic radio pulsations from SGR 1935+2154 and a detailed analysis of the properties of the radio pulses. The complex radio pulse morphology, which contains both narrow-band emission and frequency drifts, has not been seen before in other magnetars, but is similar to those of repeating FRBs - even though the luminosities are many orders of magnitude different. The observations suggest that radio emission originates from the outer magnetosphere of the magnetar, and the surface heating due to the bombardment of inward-going particles from the radio emission region is responsible for the observed X-ray spectral hardening.Comment: 47 pages, 11 figure

Epidemiological characteristics of respiratory disease mortality in residents of Baoshan，Shanghai 2009‒2020

ObjectiveTo investigate the epidemiological characteristics of respiratory disease mortality in Baoshan residents during the period of 2009‒2020.MethodsRespiratory disease deaths of Baoshan residents from 2009‒2020 were collected. ICD-10 codes were used to classify the causes of death， and R-4.2.1 was applied for statistical analysis. The average annual percent change （AAPC） of standardized mortality rates of different respiratory diseases were analyzed by using Joinpoint 4.9.0.0.ResultsThe average annual mortality rate of respiratory diseases in Baoshan from 2009 to 2020 was 58.86/105， and the standardized mortality rate was 35.62/105， which was the 3rd leading cause of mortality. The mortality rate of respiratory diseases was higher in men than in women （χ2=46.70， P<0.001）. COPD ranked first among respiratory diseases in Baoshan from 2009 to 2020， followed by pneumonia， asthma and pneumoconiosis in that order. The standardized mortality rate for COPD decreased from 38.66/105 in 2009 to 19.88/105 in 2020 （AAPC=-6.6%， 95%CI： -8.2% to -4.9%， P<0.001）. The standardized mortality rate of asthma decreased from 2.86/105 in 2009 to 1.43/105 in 2020 （AAPC=-5.8%， 95%CI： -8.8% to -2.8%， P<0.01）. The standardized mortality rate of pneumoconiosis decreased from 0.64/105 in 2009 to 0.12/105 in 2020 （AAPC=-7.4%， 95%CI： -13.0% to -1.5%， P<0.05）. The standardized mortality rate for pneumonia decreased from 2.63/105 in 2009 to 0.70/105 in 2020 （AAPC=-6.2%， 95%CI： -12.2% to 0.2%， P=0.056）， but not statistically significant. The annual average mortality rates of COPD， pneumonia and asthma were all highest in January. Crude mortality rates for COPD （χ2=2 669.01， P<0.001）， pneumonia （χ2=217.82， P<0.001）， asthma （χ2=100.09， P<0.001）， pneumoconiosis （χ2=26.46， P<0.001） and all categories of respiratory diseases （χ2=2 995.84， P<0.001） increased with age showed an increasing trend. The crude mortality rates for COPD （χ2=101.69， P<0.001）， pneumonia （χ2=7.39， P<0.01） and asthma （χ2=7.41， P<0.01） were higher in the central than in the northern part of Baoshan District， while the crude mortality rate for COPD （χ2=19.97， P<0.001） was higher in the central than in the southern part.ConclusionThe attention should be focused on COPD； increased detection in males and the elderly， especially in winter and spring； and a good balance between environmental and economic when planning the regional development

A novel model to predict phase equilibrium state of hydrates from the relationship of gas solubility

The study of hydrate phase equilibrium is crucial for ensuring the safety of natural gas pipeline transportation and the process of hydrate recovery. While scientists typically focus on the chemical potential of hydrates, the role of gas solubility in hydrate phase equilibrium remains unclear, and this study fills this gap. This work investigated the solubility of gas at the equilibrium point of the hydrate phase through model calculations. Additionally, a new model of hydrate phase equilibrium is established based on the relationship between solubility. Firstly, a solubility model based on gas-liquid equilibrium theory showed higher prediction accuracy in comparison to the PR equation and Duan model and was then used to calculate gas solubility under hydrate phase equilibrium conditions. Afterwards, a novel model was developed to predict hydrate equilibrium state based on the relationship between gas solubility and hydrate phase equilibrium temperature, and it was further compared with the Chen–Guo model and CSMGem in terms of prediction accuracy under pure water and brine settings. The results showed: (a) The calculation deviation of the solubility model was 0.7–8.7% in pure water settings and 2.6–11.7% in brine settings; (b) A strong linear correlation between the phase equilibrium temperature of hydrates and gas solubility was also found; (c) This proposed model achieved over 10 times the accuracy of the Chen–Guo model and the CSMGem in predicting the phase equilibrium state of N2 and CO2 hydrates, and 3–10 times higher accuracy than that of the Chen–Guo model and CSMGem in brine. This work suggests that the gas solubility equilibrium theory can provide a more accurate prediction of hydrate states

A radio pulsar phase from SGR J1935+2154 provides clues to the magnetar FRB mechanism

The megajansky radio burst, FRB 20200428, and other bright radio bursts detected from the Galactic source SGR J1935+2154 suggest that magnetars can make fast radio bursts (FRBs), but the emission site and mechanism of FRB-like bursts are still unidentified. Here, we report the emergence of a radio pulsar phase of the magnetar 5 months after FRB 20200428. Pulses were detected in 16.5 hours over 13 days using the Five-hundred-meter Aperture Spherical radio Telescope, with luminosities of about eight decades fainter than FRB 20200428. The pulses were emitted in a narrow phase window anti-aligned with the x-ray pulsation profile observed using the x-ray telescopes. The bursts, conversely, appear in random phases. This dichotomy suggests that radio pulses originate from a fixed region within the magnetosphere, but bursts occur in random locations and are possibly associated with explosive events in a dynamically evolving magnetosphere. This picture reconciles the lack of periodicity in cosmological repeating FRBs within the magnetar engine model