VLBI astrometry on the white dwarf pulsar AR Scorpii

AR Scorpii (AR Sco), the only-known radio-pulsing white dwarf binary, shows unusual pulsating emission at the radio, infrared, optical, and ultraviolet bands. To determine its astrometric parameters at the radio band independently, we conducted multi-epoch Very Long Baseline Interferometry (VLBI) phase-referencing observations with the European VLBI Network at 5 GHz and the Chinese VLBI Network plus the Warkworth 30-m telescope (New Zealand) at 8.6 GHz. By using the differential VLBI astrometry, we provide high-precision astrometric measurements on the parallax (pi = 8.52(-0.07)(+0.04) mas) and proper motion (mu(alpha) = 9.48(-0.07)(+0.04) mas yr(-1), mu(delta) = -51.32(-0.38)(+0.22) mas yr (-1)). The new VLBI results agree with the optical Gaia astrometry. Our kinematic analysis reveals that the Galactic space velocities of AR Sco are quite consistent with that of both intermediate polars and polars. Combined with the previous tightest VLBI constraint on the size, our parallax distance suggests that the radio emission of AR Sco should be located within the light cylinder of its white dwarf

Corrosion Characteristics of Anchor Cables in Electrolytic Corrosion Test and the Applicability of the Test Method in Study of Anchor Cable Corrosion

The selection of corrosion test method in the corrosion study of the prestressed anchors is an important issue. In this paper, the corrosion test of anchors was conducted with electrolytic corrosion test method. The corrosion characteristics of the anchor cables were examined. The effects of sodium chloride solution concentration, current, test time, and prestress level on corrosion were studied. The applicability of electrolytic corrosion method in anchor cable corrosion study is discussed subsequently. The results show that the corrosion of the anchor appears to be uniform corrosion. With the corrosion of the anchor, the central wire of the cable was basically not corroded, and the cross-sectional shape of the outer wire changes from a round to fan shape. The sodium chloride concentration and prestress level have no obvious effects on the corrosion of the anchor. The variation of test time does not affect the difference between the measured and theoretical calculated results, while a proper current in the electrolysis test may help reduce the difference. The measured corrosion rate fluctuates from −4% to 10% and tends to be higher compared with calculated results based on Faraday’s law. The study indicates that the electrolytic corrosion test is applicable in the anchor corrosion study

Endoscopy demand among county people in southeast China: A cross-sectional study

Objective: The popularization of gastroenteroscopy and the introduction of comfortable medical care have further promoted the growth of people's demand, especially the demand for painless endoscopy. This cross-sectional study aims to investigate the current situation and change in county people's demand for endoscopy to promote the development of endoscopy centers in county hospitals in southeast China. Methods: From October to December 2021, patients and their family members who came to the Gastroenterology Department in Suichang County People's Hospital of Zhejiang Province were randomly selected to complete the questionnaire. A total of 838 valid questionnaires were collected. Additionally, the original software data of the Endoscopy Center were sampled and retrieved (from October to December every year from 2018 to 2021) for statistical analysis of real-world data. Those who would choose painless endoscopy the next time in the valid questionnaires were included in the painless endoscopy group, while those who would choose ordinary endoscopy the next time were included in the ordinary endoscopy group. Results: The stepwise forward binary logistic regression model analysis showed that, patients with “secondhand smoke exposure” were more willing to choose painless endoscopy (OR = 1.459, 95% CI: 1.050–2.028, p = 0.025). However, patients with an education level of “primary and below” and “junior high school”, and patients who are suffering from “currently experiencing abdominal distension”, were more willing to choose ordinary endoscopy (OR = 0.270, 95% CI: 0.149–0.488, p < 0.001; OR = 0.528, 95% CI: 0.330–0.845, p = 0.008; OR = 0.536, 95% CI: 0.334–0.861, p = 0.010). Patients with previous experience in painless endoscopy tended to choose painless endoscopy the next time, while patients with previous experience in ordinary endoscopy tended to choose ordinary endoscopy the next time (χ2 = 140.97, p < 0.001). From 2018 to 2021, the proportion of painless endoscopy has increased yearly (p < 0.001). Most patients indicated that they would “regularly review gastroenteroscopy” (477/838, 56.9%). Conclusions: With Suichang County of Zhejiang Province as the representative, the demand for painless endoscopy for people's gastrointestinal cancer detection in southeast China has been increasing yearly. The development of endoscopy centers in county-level hospitals can basically meet the demand growth. Meanwhile, advanced concepts such as comfortable medical care and regular follow-up are gradually popularized at the grassroots level in southeast China

Overview of the Observing System and Initial Scientific Accomplishments of the East Asian VLBI Network (EAVN)

The East Asian VLBI Network (EAVN) is an international VLBI facility in East Asia and is operated under mutual collaboration between East Asian countries, as well as part of Southeast Asian and European countries. EAVN currently consists of 16 radio telescopes and three correlators located in China, Japan, and Korea, and is operated mainly at three frequency bands, 6.7, 22, and 43 GHz with the longest baseline length of 5078 km, resulting in the highest angular resolution of 0.28 milliarcseconds at 43 GHz. One of distinct capabilities of EAVN is multi-frequency simultaneous data reception at nine telescopes, which enable us to employ the frequency phase transfer technique to obtain better sensitivity at higher observing frequencies. EAVN started its open-use program in the second half of 2018, providing a total observing time of more than 1100 h in a year. EAVN fills geographical gap in global VLBI array, resulting in enabling us to conduct contiguous high-resolution VLBI observations. EAVN has produced various scientific accomplishments especially in observations toward active galactic nuclei, evolved stars, and star-forming regions. These activities motivate us to initiate launch of the &rsquo;Global VLBI Alliance&rsquo; to provide an opportunity of VLBI observation with the longest baselines on the earth