Dual-frequency EVN Observations of a Large Sample of Distant Radio Quasars

Milliarcsecond-scale observations of high-redshift radio quasars provide unique insight to jet structure, formation and evolution. To date, only a handful of already known high-redshift (z > 4) radio quasars had been imaged with very long baseline interferometry (VLBI). To substantially increase the sample available for studying the population of high-redshift radio-loud active galactic nuclei, we selected 13 radio quasars for imaging with the European VLBI Network (EVN) at 1.7 and 5 GHz. Here we present the preliminary analysis of the experiment lasting for almost three years, by investigating the spectral characteristics, morphology and brightness temperature of the sources. Compact radio emission was detected in all objects. Our results indicate that about half of the sample consists of unbeamed radio sources, some of which show significant offset between the optical and radio positions

VLBI detection of the AE Aqr twin, LAMOST J024048.51+195226.9

LAMOST J024048.51+195226.9 (J0240+1952) was recently identified as the second AE Aquarii (AE Aqr)-type cataclysmic variable, possessing the fastest known rotating white dwarf. We performed a Very Long Baseline Interferometry (VLBI) observation of J0240+1952 utilizing the European VLBI Network at 1.7\,GHz, to obtain the first view of the radio morphology on mas scale. Our high-resolution VLBI image clearly shows that the radio emission is compact on mas scale ($\lesssim2$\,AU), with no evidence for a radio jet or extended emission. The compact radio source has an average flux density of $\sim0.37$\,mJy, and its brightness temperature is given at $\gtrsim2.3\times10^{7}$\,K, confirming a non-thermal origin. The emission exhibits irregular variations on a time-scale of tens of minutes, similar to the radio flares seen in AE Aqr. The measured VLBI position of J0240+1952 is consistent with that derived from \textit{Gaia}. Our results favour the model in which the radio emission is attributed to a superposition of synchrotron radiation from expanding magnetized blobs of this system

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

A small radio galaxy at z=4.026

Less than 200 radio-loud active galactic nuclei are known above redshift 4. Around 40 of them have been observed at milliarcsecond (mas) scale resolution with very long baseline interferometry (VLBI) technique. Some of them are unresolved, compact, relativistically beamed objects, and blazars with jets pointing at small angles to the observer's line of sight. But there are also objects with no sign of relativistic beaming possibly having larger jet inclination angles. In a couple of cases, X-ray observations indicate the presence of relativistic beaming contrary to the VLBI measurements made with the European VLBI Network. J1420+1205 is a prominent example, where our 30-100 mas-scale enhanced multi element remotely linked interferometer network radio observations revealed a rich structure reminiscent of a small radio galaxy. It shows a bright hotspot that might be related to the denser interstellar medium around a young galaxy at an early cosmological epoch

Multiple positive solutions for Schrödinger-Poisson system with singularity on the Heisenberg group

Abstract In this work, we study the following Schrödinger-Poisson system { − Δ H u + μ ϕ u = λ u − γ , in  Ω , − Δ H ϕ = u 2 , in  Ω , u > 0 , in  Ω , u = ϕ = 0 , on  ∂ Ω , $$\textstyle\begin{cases} -\Delta _{H}u+\mu \phi u=\lambda u^{-\gamma}, &\text{in } \Omega , \\ -\Delta _{H}\phi =u^{2}, &\text{in } \Omega , \\ u>0, &\text{in } \Omega , \\ u=\phi =0, &\text{on } \partial \Omega , \end{cases}$$ where Δ H $\Delta _{H}$ is the Kohn-Laplacian on the first Heisenberg group H 1 $\mathbb{H}^{1}$ , and Ω ⊂ H 1 $\Omega \subset \mathbb{H}^{1}$ is a smooth bounded domain, μ = ± 1 $\mu =\pm 1$ , 0 0 $\lambda >0$ are some real parameters. For the above system, we prove the existence and uniqueness of positive solution for μ = 1 $\mu =1$ and each λ > 0 $\lambda >0$ . Multiple solutions of the system are also considered for μ = − 1 $\mu =-1$ and λ > 0 $\lambda >0$ small enough using the critical point theory for nonsmooth functional

A retrospective study of risk factors for early-onset neonatal sepsis with intrapartum maternal fever

Background Intrapartum fever is a well-known risk factor for adverse perinatal outcomes. In this study, we evaluated the clinical features for intrapartum maternal fever and investigated the risk factors for neonatal early-onset sepsis (EOS) with intrapartum maternal fever. Methods This retrospective cohort study involved a total of 568 neonates born to mothers with intrapartum maternal fever (temperature peak ≥38 degree Celsius) in Hangzhou Women’s Hospital from January 1st to December 31st, 2019. Neonates were assigned to the EOS and non-sepsis groups based on the diagnostic criteria for early-onset neonatal sepsis,. Demographic data, clinical information and laboratory test results were evaluated to assess the risk factors for EOS. Results A total of 568 neonates were included in this study, 84 of whom were diagnosed with EOS. The EOS group was significantly different from the non-sepsis group in 11 items including the both white blood cell (WBC) count and C-reactive protein (CRP) level of the mother before delivery (p < 0.05). A logistic regression analysis revealed that a high maternal WBC count before delivery (OR = 3.261, p = 0.019) and a maternal histological chorioamnionitis (HCA) diagnosis (OR = 5.608, p = 0.002) were independent risk factors for EOS. The optimal cut-off value for WBC (before delivery) was 16.75 × 10*9/L for EOS, according to receiver operating characteristic analysis (area under curve was 0.821). Conclusions Elevated prenatal maternal WBC counts and maternal HCA diagnosis are both independently associated with EOS. Prenatal maternal WBC counts can be used as a sensitive indicator to predict EOS early

Impacts of Urban Green Space on Land Surface Temperature from Urban Block Perspectives

Urban green space (UGS) can be regarded as an effective approach to mitigate urban heat island (UHI) effects. Many studies have investigated the impacts of composition and configuration of UGS on land surface temperature (LST), while little attention has been paid to the impacts among different urban blocks. Thus, taking 1835 urban blocks in Beijing as samples, including low-rise point (LRP), low-rise street (LRS), low-rise block (LRB), mid-rise point (MRP), mid-rise street (MRS), mid-rise block (MRB), high-rise point (HRP), high-rise street (HRS) and high-rise block (HRB), this study investigated the impacts of UGS on LST among different urban blocks. The results showed that UGS serves as cold islands among different urban blocks. Percentage of landscape (PLAND) of UGS in all types of urban blocks, edge density (ED) of UGS in MRS, area-weighted fractal dimension index (FRAC_AM) of UGS in HRS and HRB show significantly negative impacts on LST, while aggregation index (AI) of UGS in LRP shows significantly positive impacts. The findings suggest that both composition and configuration of UGS can affect LST among different urban blocks and rational allocation of UGS would be effective for mitigating UHI effects

Effects of miR-424 on Proliferation and Migration Abilities in Non-small Cell Lung Cancer A549 Cells and Its Molecular Mechanism

Background and objective The inhibitory ability of miR-424 on the proliferation of renal carcinoma cell and the migration and invasion of cancer cells has been widely explored and demonstrated. However, the effects of miR-424 on non-small cell lung cancer (NSCLC) have not been systematically examined. In this study, detected the growth and invasion effect of miR-424 in NSCLC A549 cell. The migration and molecular mechanism of this cell are also detected. Methods NSCLC A549 cell was transfected with miR-424 and its inhibitor. After transfection, the proliferation ability of A549 cell was detectedby CCK8 assay. Then, the migration ability in A549 cell was detected by migration assays. Furthermore, the expression level of MMP2 and MMP9 in A549 was detected by Western blot and immune fluorescence. The 3'UTR of E2F6 was cloned into luciferase reporter vector and its enzymatic activitywas detected to verify whether miR-424 can target E2F6. The expression level of E2F6 in a549 cell after transfecing with miR-424 was detected by Western blot. Results After transfection of miR-424, the proliferation and migration abilities were remarkably decreased and the expression level of MMP-2 and MMP-9 were down-regulated in A549. Moreover, MiR-424 inhibited the enzymatic activity of luviferase reporter vector of E2F6. Specifically, the expression level of E2F6 was down-regulated in A549. Conclusion miR-424 can inhibit the proliferation and migration abilities of A549 by negatively regulating the expression of E2F6