Precessing jet nozzle connecting to a spinning black hole in M87

The nearby radio galaxy M87 offers a unique opportunity to explore the connections between the central supermassive black hole and relativistic jets. Previous studies of the inner region of M87 revealed a wide opening angle for the jet originating near the black hole. The Event Horizon Telescope resolved the central radio source and found an asymmetric ring structure consistent with expectations from General Relativity. With a baseline of 17 years of observations, there was a shift in the jet's transverse position, possibly arising from an eight to ten-year quasi-periodicity. However, the origin of this sideways shift remains unclear. Here we report an analysis of radio observations over 22 years that suggests a period of about 11 years in the position angle variation of the jet. We infer that we are seeing a spinning black hole that induces the Lense-Thirring precession of a misaligned accretion disk. Similar jet precession may commonly occur in other active galactic nuclei but has been challenging to detect owing to the small magnitude and long period of the variation.Comment: 41 pages, 7 figures, 7 table

Genetic Diversity and Population Structure of Two Lancelets Along the Coast of China

National Natural Science Foundation of China [30830023]; Department of Science and Technology of Shenzhen [JSF201006290026A]The western Pacific lancelet, once recognized as a monospecies, Branchiostoma belcheri, is a frequently used model in evolutionary and developmental studies, and researchers usually collect samples from the field without consideration of species identification and genetic divergence. However, recent studies found divergence of the lancelets from different localities and divided this monospecies into two separate species (B. belcheri and B. japonicum). To further estimate the genetic diversity of lancelet populations and the cause of their formation, we sampled 70 individuals from four major distribution areas along the coast of China, using both mitochondrial DNA and microsatellite markers in this investigation. Our results demonstrate that the two species possess extremely high genetic diversity at both mtDNA sequence level (h approaches 1.0) and microsatellite loci (He is above 0.8). Further demographic analysis reveals that the lancelets B. japonicum and B. belcheri underwent a recent historical population expansion at approximately 117,000 and 73,000 years ago respectively. Analyses on the population genetic structure revealed weak differentiation among different local populations. No evident differentiation was found among different local populations of the same species using mtDNA sequence data, but certain divergences among them were identified based on the microsatellite data. We suggest that discontinuous habitats may be responsible for the phylogeographic structure of the lancelets along China coasts

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

Full list of authors: Akiyama, Kazunori; Algaba, Juan-Carlos; An, Tao; Asada, Keiichi; Asanok, Kitiyanee; Byun, Do-Young; Chanapote, Thanapol; Chen, Wen; Chen, Zhong; Cheng, Xiaopeng; Chibueze, James O.; Cho, Ilje; Cho, Se-Hyung; Chung, Hyun-Soo; Cui, Lang; Cui, Yuzhu; Doi, Akihiro; Dong, Jian; Fujisawa, Kenta; Gou, Wei; Guo, Wen; Hada, Kazuhiro; Hagiwara, Yoshiaki; Hirota, Tomoya; Hodgson, Jeffrey A.; Honma, Mareki; Imai, Hiroshi; Jaroenjittichai, Phrudth; Jiang, Wu; Jiang, Yongbin; Jiang, Yongchen; Jike, Takaaki; Jung, Dong-Kyu; Jung, Taehyun; Kawaguchi, Noriyuki; Kim, Dong-Jin; Kim, Hyo-Ryoung; Kim, Jaeheon; Kim, Jeong-Sook; Kim, Kee-Tae; Kim, Soon-Wook; Kino, Motoki; Kobayashi, Hideyuki; Koyama, Shoko; Kramer, Busaba H.; Lee, Jee-Won; Lee, Jeong Ae; Lee, Sang-Sung; Lee, Sang Won; Li, Bin; Li, Guanghui; Li, Xiaofei; Li, Zhixuan; Liu, Qinghui; Liu, Xiang; Lu, Ru-Sen; Motogi, Kazuhito; Nakamura, Masanori; Niinuma, Kotaro; Oh, Chungsik; Oh, Hongjong; Oh, Junghwan; Oh, Se-Jin; Oyama, Tomoaki; Park, Jongho; Poshyachinda, Saran; Ro, Hyunwook; Roh, Duk-Gyoo; Rujopakarn, Wiphu; Sakai, Nobuyuki; Sawada-Satoh, Satoko; Shen, Zhi-Qiang; Shibata, Katsunori M.; Sohn, Bong Won; Soonthornthum, Boonrucksar; Sugiyama, Koichiro; Sun, Yunxia; Takamura, Mieko; Tanabe, Yoshihiro; Tazaki, Fumie; Trippe, Sascha; Wajima, Kiyoaki; Wang, Jinqing; Wang, Na; Wang, Shiqiang; Wang, Xuezheng; Xia, Bo; Xu, Shuangjing; Yan, Hao; Yang, Wenjun; Yeom, Jae-Hwan; Yi, Kunwoo; Yi, Sang-Oh; Yonekura, Yoshinori; Yoon, Hasu; Yu, Linfeng; Yuan, Jianping; Yun, Youngjoo; Zhang, Bo; Zhang, Hua; Zhang, Yingkang; Zhao, Guang-Yao; Zhao, Rongbing; Zhong, Weiye.--This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).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 ’Global VLBI Alliance’ to provide an opportunity of VLBI observation with the longest baselines on the earth. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.This work is funded by following: JSPS (Japan Society for the Promotion of Science) Grant-in Aid for Scientific Research (KAKENHI) (S) 18H05222 (T.H.), (A) 16H02167 (H.I.), 18H03721 (K.N.), 21H04524 (H.I.), 22H00157 (K.H.), (B) 18KK0090 (K.H.), 21H01120 (Y.Y. (Yoshinori Yonekura)), (C) 17K05398 (T.H.), 19K03921 (K.S.), 21K03628 (S.S-S.), JSPS Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area) 21H00032 (Y.Y. (Yoshinori Yonekura)), 21H00047 (H.I.), JSPS Grant-in-Aid for Transformative Research Areas (A) 20H05845 (T.H.), the Grant of PIIF Heiwa Nakajima Foundation in 2019 (K.S.), and the Mitsubishi Foundation 201911019 (K.H.). K.A. (Kazunori Akiyama) is financially supported by grants from the National Science Foundation (AST-1935980, AST-2034306, AST-2107681, AST-2132700, OMA-2029670). L.C. is supported by the Chinese Academy of Sciences (CAS) ’Light of West China’ Program (No. 2021-XBQNXZ-005) and the National Science Foundation of China (NSFC; No. U2031212 and 61931002). W.C. is supported by NSFC (No. 11903079). Z.C. is supported by NSFC (No. U1931135). W.J. is supported by NSFC (No. 12173074). R.-S.L. is supported by the Max Planck Partner Group of the MPG and the CAS, the Key Program of the NSFC (No. 11933007), the Key Research Program of Frontier Sciences, CAS (No. ZDBS-LY-SLH011), and the Shanghai Pilot Program for Basic Research - CAS, Shanghai Branch (No. JCYJ-SHFY-2022-013). S.T. acknowledges financial support from the National Research Foundation of Korea (NRF) through grant no. 2022R1F1A1075115. B.Z. is supported by the NSFC (No. U1831136 and U2031212) and Shanghai Astronomical Observatory (N-2020-06-09-005).With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.Peer reviewe

Quadruple-Ridged Flared Horn Operating from 8 to 50 GHz

This communication proposes a compact, high performance, quadruple-ridged flared horn (QRFH) operating from 8 to 50 GHz. A prototype fed by two coaxial connectors has been designed and fabricated based on the combination of a four-petal structure and a back plate. Measurements show that the input reflection coefficients are below -10 dB over more than 6:1 frequency range. Radiation patterns were measured in an anechoic chamber, and good agreement was found with the simulated results. Physical optics calculations predict an average of 68% aperture efficiency with the feed installed on the SKA-shaped offset Gregorian reflector. The horn is a good demonstration at very high frequencies of a wideband feed for radio telescopes

Quadruple-Ridged Flared Horn Operating from 8 to 50 GHz

This communication proposes a compact, high performance, quadruple-ridged flared horn (QRFH) operating from 8 to 50 GHz. A prototype fed by two coaxial connectors has been designed and fabricated based on the combination of a four-petal structure and a back plate. Measurements show that the input reflection coefficients are below -10 dB over more than 6:1 frequency range. Radiation patterns were measured in an anechoic chamber, and good agreement was found with the simulated results. Physical optics calculations predict an average of 68% aperture efficiency with the feed installed on the SKA-shaped offset Gregorian reflector. The horn is a good demonstration at very high frequencies of a wideband feed for radio telescopes

Anterior Lumbar Interbody Fusion for Degenerative Discogenic Low Back Pain: Evaluation of L4–S1 Fusion

Abstract The treatment of degenerative discogenic pain is controversial, and anterior lumbar fusion for the treatment of degenerative discogenic low back pain has also been a controversial topic for over a generation. The aim of this systematic review was to evaluate the outcome of different anterior lumbar fusion levels for degenerative discogenic low back pain. In this study, we performed a clinical outcome subgroup analysis. The outcomes of 84 consecutive patients who underwent anterior lumbar interbody fusion from 2004 to 2009 were reviewed. The operative time, intraoperative blood loss, hospital stay, Oswestry Disability Index (ODI), visual analog scale (VAS) results, and complication rate were recorded separately. Medical indications were degenerative disc disease (73.8%), postdiscectomy disc disease (16.1%), and disc herniation (9.5%). Patients with severe spondylolysis or disc degeneration, with more than 3 or multilevel lesions, were excluded. The mean operative time was 124.5 ± 10.9 min (range 51–248 min), the mean intraoperative blood loss was 242.1 ± 27.7 mL (range 50–2700 mL), the mean hospital stay was 3.9 ± 1.1 days (range 3–6 days), the mean preoperative VAS score was 7.5 ± 1.4, and the mean preoperative ODI score was 60.0 ± 5.7. At the 1-year follow-up, the mean postoperative VAS score was 3.3 ± 1.3 and the mean postoperative ODI score was 13.6 ± 3.4 (P < 0.05). L4–L5 disc fusion led to better clinical results than 2-level L4–L5/L5–S1 disc fusion. Additionally, the 2-level fusion of L4–L5/L5–S1 had better clinical results than the L5–S1 disc fusion at both the 1 and 2-year postoperative follow-ups regarding the VAS score and the ODI score. The rate of complications was more frequent in the 2-level L4–L5/L5–S1 group (27.3%) (group C) than in the L4–L5 group (9.1%) (group A) and the L5–S1 group (12.5%) (group B). There was no difference between the L4–L5 group (9.1%) and the L5–S1 group (12.5%). A venous tear occurred during surgery and was successfully repaired in 6 of the 84 patients. Also, out of the 84 patients, 6 were found with pseudarthrosis during the follow-up, and these patients underwent a spinal fusion with instrumentation, with a posterior approach after a mean of 1 year. The complications secondary to the surgical approach were persistent abdominal pain (1/84, 1.2%) and wound dehiscence (1/84, 1.2%). Anterior lumbar interbody fusion for L4–L5 had better clinical results than the 2-segmental L4–L5/L5–S1 disc fusion, and the 2-segmental L4–L5/L5–S1 disc fusion had better clinical results than the L5–S1 disc fusion. Also, the 2-segmental L4–L5/L5–S1 disc fusion had a higher complication rate (27.3%), but there was no difference between the L4–L5 group (9.1%) and the L5–S1 group (12.5%)