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8 results on '"Yi-Xuan Shao"'

1. Discovery of a Millisecond Pulsar Associated with Terzan 6

Author

Shi-Jie Gao, Yi-Xuan Shao, Pei Wang, Ping Zhou, Xiang-Dong Li, Lei Zhang, Joseph W. Kania, Duncan R. Lorimer, and Di Li

Subjects
Millisecond pulsars, Globular star clusters, Neutron stars, Astrophysics, QB460-466
Abstract

Observations show that globular clusters (GCs) might be among the best places to find millisecond pulsars (MSPs). However, the GC Terzan 6 seems to be an exception without any pulsar discovered, although its high stellar encounter rate suggests that it harbors dozens of them. We report the discovery of the first radio pulsar, PSR J1750–3116A, likely associated with Terzan 6 in a search of C -band (4–8 GHz) data from the Robert C. Byrd Green Bank Telescope with a spin period of 5.33 ms and dispersion measure (DM) ≃ 383 pc cm ^−3 . The mean flux density of this pulsar is approximately 3 μ Jy. The DM agrees well with predictions from the Galactic free electron density model, assuming a distance of 6.7 kpc for Terzan 6. PSR J1750–3116A is likely an isolated MSP, potentially formed through dynamical interactions, considering the core-collapsed classification and the exceptionally high stellar encounter rate of Terzan 6. This is the highest radio frequency observation that has led to the discovery of a pulsar in a GC to date. While L -band (1–2 GHz) observations of this cluster are unlikely to yield significant returns due to propagation effects, we predict that further pulsar discoveries in Terzan 6 will be made by existing radio telescopes at higher frequencies.

Published
2024
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2. Triggering the Untriggered: The First Einstein Probe-detected Gamma-Ray Burst 240219A and Its Implications

Author

Yi-Han Iris Yin, Bin-Bin Zhang, Jun Yang, Hui Sun, Chen Zhang, Yi-Xuan Shao, You-Dong Hu, Zi-Pei Zhu, Dong Xu, Li An, He Gao, Xue-Feng Wu, Bing Zhang, Alberto Javier Castro-Tirado, Shashi B. Pandey, Arne Rau, Weihua Lei, Wei Xie, Giancarlo Ghirlanda, Luigi Piro, Paul O’Brien, Eleonora Troja, Peter Jonker, Yun-Wei Yu, Jie An, Run-Chao Chen, Yi-Jing Chen, Xiao-Fei Dong, Rob Eyles-Ferris, Zhou Fan, Shao-Yu Fu, Johan P. U. Fynbo, Xing Gao, Yong-Feng Huang, Shuai-Qing Jiang, Ya-Hui Jiang, Yashaswi Julakanti, Erik Kuulkers, Qing-Hui Lao, Dongyue Li, Zhi-Xing Ling, Xing Liu, Yuan Liu, Jia-Yu Mou, Xin Pan, Varun, Daming Wei, Qinyu Wu, Muskan Yadav, Yu-Han Yang, Weimin Yuan, and Shuang-Nan Zhang

Subjects
Transient sources, X-ray transient sources, High energy astrophysics, Gamma-ray bursts, Astrophysics, QB460-466
Abstract

The Einstein Probe (EP) achieved its first detection and localization of a bright X-ray flare, EP240219a, on 2024 February 19, during its commissioning phase. Subsequent targeted searches triggered by the EP240219a alert identified a faint, untriggered gamma-ray burst (GRB) in the archived data of Fermi Gamma-ray Burst Monitor (GBM), Swift Burst Alert Telescope (BAT), and Insight-HXMT/HE. The EP Wide-field X-ray Telescope (WXT) light curve reveals a long duration of approximately 160 s with a slow decay, whereas the Fermi/GBM light curve shows a total duration of approximately 70 s. The peak in the Fermi/GBM light curve occurs slightly later with respect to the peak seen in the EP/WXT light curve. Our spectral analysis shows that a single cutoff power-law (PL) model effectively describes the joint EP/WXT–Fermi/GBM spectra in general, indicating coherent broad emission typical of GRBs. The model yielded a photon index of ∼–1.70 ± 0.05 and a peak energy of ∼257 ± 134 keV. After detection of GRB 240219A, long-term observations identified several candidates in optical and radio wavelengths, none of which was confirmed as the afterglow counterpart during subsequent optical and near-infrared follow-ups. The analysis of GRB 240219A classifies it as an X-ray-rich GRB (XRR) with a high peak energy, presenting both challenges and opportunities for studying the physical origins of X-ray flashes, XRRs, and classical GRBs. Furthermore, linking the cutoff PL component to nonthermal synchrotron radiation suggests that the burst is driven by a Poynting flux-dominated outflow.

Published
2024
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3. Upper Limits on the Radio Pulses from Magnetars and a Central Compact Object with FAST

Author

Wan-Jin Lu, Ping Zhou, Pei Wang, Yi-Xuan Shao, Xiang-dong Li, Jacco Vink, Di Li, and Yang Chen

Subjects
Pulsars, Neutron stars, Magnetars, Astrophysics, QB460-466
Abstract

Magnetars and central compact objects (CCOs) are subgroups of neutron stars that show a number of properties distinguished from canonical radio pulsars. We performed radio observations of three magnetars, SGR 0418+5729, 1E 2259+586, and 4U 0142+61, and a CCO, PSR J1852+0040, with the Five-hundred-meter Aperture Spherical radio Telescope at 1.25 GHz, aiming to search for radio pulsations in their quiescent states. During two observation epochs, no radio pulses have been detected toward any target above a significance of signal-to-noise ratio = 7 from either the direct folding or blind search. We provided the most stringent upper limit of radio flux (≲2–4 μ Jy) for the magnetars and the CCO. For the magnetars with long periods, the real upper limits are likely 1 order of magnitude larger due to the red noise. The deep radio observations suggest that these magnetars and the CCO are indeed radio-quiet sources or unfavorably beamed.

Published
2024
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4. GTC Optical/Near-infrared Upper Limits and NICER X-Ray Analysis of SGR J1935+2154 for the Outburst in 2022

Author

Yi-Xuan Shao, Ping Zhou, Xiang-Dong Li, Bin-Bin Zhang, Alberto Javier Castro-Tirado, Pei Wang, Di Li, Zeng-Hua Zhang, Zi-Jian Zhang, You-Dong Hu, and Shashi B. Pandey

Subjects
Magnetars, Neutron stars, Soft gamma-ray repeaters, X-ray bursts, X-ray transient sources, Astrophysics, QB460-466
Abstract

The Galactic magnetar SGR J1935+2154 has undergone another outburst since 2022 October 10. We present the results of searching for an optical/near-infrared (NIR) counterpart of SGR J1935+2154 before and during this outburst. No counterpart was detected at the magnetar’s position in $r^{\prime} $ and $z^{\prime} $ bands, providing stringent upper limits of $r^{\prime} \gtrsim 28.65$ and $z^{\prime} \gtrsim 26.27$ . Using archival X-ray data from NICER, we investigated the properties of the bursts and the spectral evolution of persistent emission. The burst flux F showed a power-law distribution of N ∝ F ^−0.76±0.10 for flux ≳2.6 × 10 ^−9 erg cm ^−2 s ^−1 , while the temperature and radius followed a log-normal distribution with ${kT}={1.63}_{-0.50}^{+0.73}\ \mathrm{keV}$ and ${R}_{\mathrm{bb}}={4.35}_{-1.35}^{+1.95}\ \mathrm{km}$ , respectively. The persistent flux evolution experienced a quick decay and an enhancement ∼27 days after the Burst Alert Telescope trigger. Using the NIR and X-ray emission, together with the Gran Telescopio Canarias optical/NIR upper limits, we discussed the origin of the NIR emission from the magnetar based on the fallback disk model and magnetosphere model. We found that either model cannot be ruled out with currently available data. Further mid-infrared observations are needed to find out the mechanism for producing the NIR emission from SGR J1935+2154.

Published
2024
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5. [Effect of acupuncture on intestinal flora and TLR4 in brain and intestinal tissues in rats with stress gastric ulcer]

Author

Jia-Yu, Zhao, Tu-Nan, Wang, Liu-Jing, Wang, Xue, Ting, Ying-Qi, Wu, Zi-Xian, Zhou, Yi-Chen, Yang, Yi-Xuan, Shao, and Hui-Fang, Ma

Subjects
Male, Rats, Sprague-Dawley, Toll-Like Receptor 4, Acupuncture Therapy, Animals, Brain, Stomach Ulcer, Acupuncture Points, Gastrointestinal Microbiome, Rats
Abstract

To observe the effect of acupuncture at "Guanyuan" (CV 4) and "Xiajuxu" (ST 39) on intestinal flora and Toll-like receptors-4 (TLR4) in brain and intestinal tissue in rats with stress gastric ulcer (SGU), and to explore the possible mechanism of acupuncture for SGU.Thirty-one male SD rats were randomly divided into a blank group (Compared with the blank group, the gastric mucosal damage index was significantly increased in the model group (Acupuncture at "Guanyuan" (CV 4) and "Xiajuxu" (ST 39) could alleviate SGU in rats, and its mechanism may be related to increasing the diversity of intestinal flora, promoting the disorder of intestinal flora to normal, and reducing the overexpression of TLR4 in brain and intestinal tissues.

Published
2021

6. [Effect of acupuncture on serum inflammatory cytokines and intestinal flora in rats with stress-induced gastric ulcer]

Author

Ting, Xue, Liu-Jing, Wang, Ying-Qi, Wu, Tu-Nan, Wang, Jia-Yu, Zhao, Jing-Ting, Li, Jia-Jia, Ma, Chen-Lu, Fu, Peng, Zhang, Yi-Xuan, Shao, Yi-Chen, Yang, Zi-Xian, Zhou, and Hui-Fang, Ma

Subjects
Rats, Sprague-Dawley, Acupuncture Therapy, Animals, Cytokines, Stomach Ulcer, Gastrointestinal Microbiome, Rats
Abstract

To investigate the effect of acupuncture on serum inflammatory cytokines and intestinal flora in rats with stress-induced gastric ulcer (SGU), and to explore the mechanism of acupuncture in the treatment of SGU.Sprague-Dawley rats were randomly divided into blank, model, acupuncture, and medication groups, with 7 rats in each group. Restraint water-immersion stress was used to establish the model of SGU. The rats in the acupuncture group were given acupuncture at "Zhongwan"(CV12) and bilateral "Zusanli"(ST36) for 20 min, once a day for 5 days, and those in the medication group were given 2 mL solution of Omeprazole enteric-coated tablets (0.2 mg/kg) by gavage, once a day for 5 days. The Guth method was used to calculate the gastric mucosa damage index, HE staining was used to observe the histopathological changes of the gastric mucosa, ELISA was used to measure the serum levels of interleukin-4 (IL-4) and interleukin-6 (IL-6), and 16S rDNA sequencing method was used to observe the change in intestinal flora.Compared with the blank group, the model group had a significant increase in gastric mucosa damage index (Acupuncture at CV12 and ST36 can down-regulate the content of serum IL-6, up-regulate the content of serum IL-4, maintain the relative homeostasis of inflammatory cytokines, and regulate the community structure of intestinal flora, and thus help to repair the damage of gastric mucosa.

Published
2020

7. [Effect of acupuncture on intestinal flora in rats with stress gastric ulcer]

Author

Liu-Jing, Wang, Ting, Xue, Ying-Qi, Wu, Jia-Yu, Zhao, Tu-Nan, Wang, Jing-Ting, Li, Chen-Lu, Fu, Jia-Jia, Ma, Li-Ping, Zhang, Yi-Xuan, Shao, Yi-Chen, Yang, Zi-Xian, Zhou, and Hui-Fang, Ma

Subjects
Rats, Sprague-Dawley, Random Allocation, Acupuncture Therapy, Animals, Stomach Ulcer, Acupuncture Points, Gastrointestinal Microbiome, Rats
Abstract

To observe the effect of acupuncture at "Baihui" (GV 20), "Zhongwan" (CV 12) and "Zusanli" (ST 36) on intestinal flora in rats with stress gastric ulcer (SGU) , and to explore the mechanism of acupuncture promoting SGU recovery.Thirty-one SPF SD rats were randomly divided into a control group (7 rats), a model control group (8 rats), an acupuncture group (8 rats) and a medication group (8 rats). The rats in the model group, acupuncture group and medication group were selected to applied the improved restraint water-immersion stress method to establish the SGU model. After modeling, the rats in the control group and model group were fixed and restrained for 20 min every day for a total of 5 days; the rats in the acupuncture group were intervented with acupuncture at "Baihui" (GV 20), "Zhongwan" (CV 12) and "Zusanli" (ST 36), once a day, 20 min each time, and twisting needle for 30 s every 5 min for a total of 5 days; the rats in the medication group were gavaged by solution of omeprazole enteric-coated tablet (200 mg/mL), 2 mL for each rat, once a day. Guth method was used to calculate the gastric mucosal damage index (GMDI), HE staining was used to observe the pathological changes of gastric mucosa, and 16SrDNA identification was used to detect the structural abundance of intestinal flora.Compared with the control group, the GMDI of rats in the model group was increased (Acupuncture can effectively improve gastric mucosal injury of SGU, and the mechanism may be related to increasing the diversity of intestinal flora and promoting the correction of the disordered intestinal flora.

Published
2020

8. [Moxibustion improved gastric ulcer by reducing contents of corticotrophin-releasing hormone and adrenocorticotropic hormone in serum and hypothalamus-pituitary tissues in rats with stress-induced gastric ulcer]

Author

Jing-Ting, Li, Han-Yu, Guan, Jia-Jia, Ma, Chen-Lu, Fu, Yi-Xuan, Shao, Liu-Jing, Wang, Ting, Xue, Ying-Qi, Wu, and Hui-Fang, Ma

Subjects
Male, Rats, Sprague-Dawley, Adrenocorticotropic Hormone, Corticotropin-Releasing Hormone, Moxibustion, Pituitary Gland, Hypothalamus, Animals, Stomach Ulcer, Rats
Abstract

To observe the effect of moxibustion of "Zhongwan" (CV12) and "Zusanli" (ST36) on histopathological changes of the gastric mucosa and contents of corticotropin-releasing hormone(CRH) and adrenocorticotrophic hormone(ACTH) in the serum, hypothalamus and pituitary tissues in rats with stress-induced gastric ulcer(SGU), so as to reveal its mechanisms underlying improvement of SGU.A total of 28 male SD rats were randomly divided into blank control, model, moxibustion, and medication groups, with 7 rats in each group. The SGU model was established by water immersion restraint stress for 3 h. Moxibustion was applied to "Zhongwan"(CV12) and bilateral "Zusanli" (ST36) for 20 min, once a day for 5 days, and rats of the medication group were treated by gavage of Omeprazole enteric-coated tablets (0.2 mg/kg) once a day for 5 days. The gastric mucosal damage index (ulcer index, UI) was measured to assess the injury severity according to Guth's me-thods. Histopathological changes of the gastric mucosa were determined by H．E. staining. The contents of CRH in serum and hypothalamus and ACTH in serum and pituitary gland tissue were assayed by using ELISA.Outcomes of H．E. staining showed gastric mucosal epithelia defect, disordered arrangement of glands, obvious mucosal hyperemia and edema, exudation of a large number of red blood cells, swelling of mucosal cells with necrosis of nuclei in the model group. These situations were relatively milder in the moxibustion and medication groups. After modeling, the UI, and the contents of CRH in the serum and hypotha-lamus, and ACTH in the serum and pituitary tissue were significantly increased in comparison with the blank control group (Moxibustion can relieve gastric mucosal injury induced by stress in water immersion restraint stress rats, which may be associated with its effects in down-regulating the levels of CRH and ACTH in se-rum, hypothalamus and pituitary tissues (inhibition of activities of hypothalamic-pituitary-adrenocortical axis)．.

Published
2019

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