分类： 物理学 >> 地球物理学、天文学和天体物理学 提交时间： 2024-02-01 合作期刊: 《Research in Astronomy and Astrophysics》
摘要： The thermal gradient is an important factor that causes degradation to the image quality of telescopes. In order to ensure the accurate alignment of the primary focus unit and the primary mirror, the hexapod platform (as a corrector) is investigated in this paper. First, a ground-based telescope with 2.5 m aperture and 3.5 deg field of view is described. The telescope is under construction, and it is expected to be finished in 2023. Second, the hexapod platform with flexure hinges utilized to adjust the primary focus unit is proposed, which is applied as a corrector. Then, the inverse kinematics of the platform is established and an open-loop control system is built based on it. Finally, the cryogenic performance test for the hexapod platform is performed. The experimental results show that the resolution and repeatability of the translation for the hexapod platform can be achieved at the micrometer level. The resolution and repeatability of the rotation can be achieved at the arc-second level. Therefore, the cryogenic performance of the hexapod platform can meet the optical imaging requirements of the wide-field ground-based telescope. The kinematic analysis and cryogenic performance tests in the paper provide a technical reference for the precise alignment of the primary focus unit and the primary mirror, which can improve the imaging quality of the telescope.
分类： 医学、药学 >> 药学 提交时间： 2022-12-26
Chen-yu Wang
Di-hong Yang
Xiao-min Niu
Lu Han
Wen Wang
Roman Filimonov
Sajid Ali Shah
Xin-yang Weng
Zheng Jiao
摘要： 目的：在非小细胞肺癌患者中，免疫检查点抑制剂联合化疗方案比传统化疗方案为患者提供了更多获益。然而，依然有部分患者无法得到获益，存在着免疫耐受的现象。临床可测量的生物标志物是预测临床结果和优化剂量策略所必需的。本研究旨在通过定量系统药理学（QSP）研究可获得的生物标志物，这些生物标志物可以预测非小细胞肺癌患者的临床结果，并优化atezolizumab和nab紫杉醇联合治疗的给药策略。 方法：使用MATLAB中的SimBiology工具箱，基于已发表的三阴性乳腺癌QSP模型开发该模型。利用该模型，我们生成了一个虚拟患者队列以进行虚拟临床试验模拟，并使用来自真实临床试验（IMpower131）的数据进行模型校准和验证。 结果：最终QSP模型预测与临床报告的疗效终点一致。患者的肿瘤中基线CD8+和CD4+T细胞密度与临床获益显著相关。Roc分析进一步揭示了它们作为联合治疗方案的预测生物标志物的潜力。虚拟临床试验模拟显示，将nab紫杉醇剂量从100 mg/m2降至75 mg/m2将导致ORR降低，但依然高于atezolizumab单药治疗。三种atezolizumab给药策略联合nab紫杉醇显示出相似的疗效。 结论：本研究提供了一个QSP模型，可用于生成虚拟患者队列并进行虚拟临床试验。我们的研究结果证明了它在预测免疫疗法和化疗的疗效、识别预测性生物标志物以及指导未来临床试验设计方面的潜力。
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We have collected 10025 foreground-background quasar pairs with projected distances $d_p0.15$ \AAaround foreground quasars, including both the LOS (line-of-sights of foreground quasars) and transverse (TRA, perpendicular to the LOS) absorptions. Both the equivalent width (the correlation coefficient $\rho=-0.915$ and the probability $P 4\sigma$) greater than that of LOS \Mgii\ absorption lines at projected distances $d_p200$ kpc. The anisotropic radiation from quasars would be the most possible interpretation for the anisotropic absorption around quasars. This could also indicate that the quasar radiation is not obviously impacting the gas halos of quasars at scales $d_p>200$ kpc.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We have collected 10025 foreground-background quasar pairs with projected distances $d_p0.15$ \AAaround foreground quasars, including both the LOS (line-of-sights of foreground quasars) and transverse (TRA, perpendicular to the LOS) absorptions. Both the equivalent width (the correlation coefficient $\rho=-0.915$ and the probability $P 4\sigma$) greater than that of LOS \Mgii\ absorption lines at projected distances $d_p200$ kpc. The anisotropic radiation from quasars would be the most possible interpretation for the anisotropic absorption around quasars. This could also indicate that the quasar radiation is not obviously impacting the gas halos of quasars at scales $d_p>200$ kpc.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Andrea Francesco Battaglia
Wen Wang
Jonas Saqri
Tatiana Podladchikova
Astrid M. Veronig
Hannah Collier
Ewan C. M. Dickson
Olena Podladchikova
Christian Monstein
Alexander Warmuth
Frédéric Schuller
Louise Harra
Säm Krucker
摘要： One of the main science questions of the Solar Orbiter and Parker Solar Probe missions deals with understanding how electrons in the lower solar corona are accelerated and how they subsequently access interplanetary space. We aim to investigate the electron acceleration and energy release sites as well as the manner in which accelerated electrons access the interplanetary space in the case of the SOL2021-02-18T18:05 event, a GOES A8 class microflare associated with a coronal jet. This study takes advantage of three different vantage points, Solar Orbiter, STEREO-A, and Earth, with observations ranging from radio to X-ray. Multi-wavelength timing analysis combined with UV/EUV imagery and X-ray spectroscopy by Solar Orbiter/STIX (Spectrometer/Telescope for Imaging X-rays) is used to investigate the origin of the observed emission during different flare phases. The event under investigation satisfies the classical picture of the onset time of the acceleration of electrons coinciding with the jet and the radio type III bursts. This microflare features prominent hard X-ray nonthermal emission down to at least 10 keV and a spectrum that is much harder than usual for a microflare with a spectral index of 2.9. From Earth's vantage point, the microflare is seen near the limb, revealing the coronal energy release site above the flare loop in EUV, which, from STIX spectroscopic analysis, turns out to be hot (at roughly the same temperature of the flare). Moreover, this region is moving toward higher altitudes over time (about 30 km/s). During the flare, the same region spatially coincides with the origin of the coronal jet. We conclude that the energy release site observed above-the-loop corresponds to the electron acceleration site, corroborating that interchange reconnection is a viable candidate for particle acceleration in the low corona on field lines open to interplanetary space.
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