分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we detect a giant HI filamentary structure in the sky region of 307$.\!\!^{\circ}$7 $<$ $\alpha$ $<$ 311$.\!\!^{\circ}$0 and 40$.\!\!^{\circ}$9 $<$ $\delta$ $<$ 43$.\!\!^{\circ}$4. The structure has a velocity range of $-$170 km s$^{-1}$ to $-$130 km s$^{-1}$, and a mean velocity of $-$150 km s$^{-1}$, putting it to a Galactocentric distance of 22 kpc. The HI structure has a length of 1.1 kpc, which appears to be so far the furthest and largest giant filament in the Galaxy and we name it Cattail. Its mass is calculated to be 6.5 $\times$ 10$^4$ M$_{\odot}$ and the linear mass density is 60 M$_{\odot}$ pc$^{-1}$. Its width is 207 pc, corresponding to an aspect ratio of 5:1. Cattail possesses a small velocity gradient (0.02 km s$^{-1}$ pc$^{-1}$) along its major axis. Together with the HI4PI data, we find that Cattail could have an even larger length, up to 5 kpc. We also identify another new elongated structure to be the extension into the Galactic first quadrant of the Outer Scutum-Centaurus (OSC) arm, and Cattail appears to be located far behind the OSC. The question about how such a huge filament is produced at the extreme Galactic location remains open. Alternatively, Cattail might be part of a new arm beyond the OSC, though it is puzzling that the structure does not fully follow the warp of the Galactic disk.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We have carried out a high-sensitivity and high-resolution radio continuum study towards a sample of 47 massive dense cores (MDCs) in the Cygnus X star-forming complex using the Karl G. Jansky Very Large Array, aiming to detect and characterize the radio emission associated with star-forming activities down to ~0.01 pc scales. We have detected 64 radio sources within or closely around the full width at half-maximum (FWHM) of the MDCs, of which 37 are reported for the first time. The majority of the detected radio sources are associated with dust condensations embedded within the MDCs, and they are mostly weak and compact. We are able to build spectral energy distributions for 8 sources. Two of them indicate non-thermal emission and the other six indicate thermal free-free emission. We have determined that most of the radio sources are ionized jets or winds originating from massive young stellar objects, whereas only a few sources are likely to be ultra-compact HII regions. Further quantitative analyses indicate that the radio luminosity of the detected radio sources increases along the evolution path of the MDCs.
分类： 医学、药学 >> 临床医学 提交时间： 2020-02-26
Jinnong,Zhang
Wenjing,Wang
Bo,Peng
Wei,Peng
Yisheng,Zhang
Yaling,Wang
Yan,Wan
Jiang,Chang
Ling,Mao
Xiaoping，Miao
Yifan,Zhou
Yanan,Li
Yu,Hu
Bo,Hu
摘要： Background: The efficient transmission of Severe Acute Respiratory Syndrome-2 Coronavirus (SARS-CoV-2) from patients to healthcare workers or family members has been a worrisome and prominent feature of the ongoing outbreak. On the basis of clinical practice and in-vitro studies, we postulated that post-exposure prophylaxis (PEP) using Arbidol is associated with decreased infection among individuals exposed to confirmed cases of COVID-19 infection. Methods: We conducted a retrospective case-control study on family members and health care workers who were exposed to patients confirmed to have SARS-CoV-2 infection by real-time RT-PCR and Chest CT from January 1 to January 16, 2020. We collected demographic information, work location of exposure, post-exposure prophylaxis information, and symptoms, if any, 24 days after exposure. The relation between post-exposure prophylaxis and infection in household contacts and healthcare workers were respectively analyzed. Results: 27 families and 124 health care workers had evidence of close exposure to patients with confirmed COVID-19. There were no differences in age, profession and sex distribution in the two groups with different post-exposure prophylaxis, table 1. Logistic regression based on the data of the family members and health care workers with Arbidol or Oseltamivir prophylaxis showed that Arbidol PEP was a strong protective factor against the development of COVID-19 (Odds ratio 0·011 , 95% CI 0·001-0·125, P=0·0003 for family members and Odds ratio 0·049, 95%CI 0·003-0·717), P= 0·0276 for health care workers). On the contrary, Oseltamivir was associated with an increase in COVID-19 infection (Odds ratio 20·446, 95% CI 1·407-297·143, P= 0·0271). Conclusions: Our findings suggest Arbidol could reduce the infection risk of the novel coronavirus in hospital and family settings. This treatment should be promoted for PEP use and should be the subject of further investigation.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Andrea Aiello
Xiao-Bo Hu
Valeria Rodríguez-Fajardo
Raul I. Hernandez-Aranda
Andrew Forbes
Benjamin Perez-Garcia
Carmelo Rosales-Guzmán
摘要： Vectorial forms of structured light that are non-separable in their spatial and polarisation degrees of freedom have become topical of late, with an extensive toolkit for their creation and control. In contrast, the toolkit for quantifying their non-separability, the inhomogeneity of the polarisation structure, is far less developed, and in some cases fails altogether. To overcome this, here we introduce a new measure for vectorial light, which we demonstrate both theoretically and experimentally. We consider the general case where the local polarisation homogeneity can vary spatially across the field, from scalar to vector, a condition that can arise naturally if the composite scalar fields are path separable during propagation, leading to spatially disjoint vectorial light. We show how the new measure correctly accounts for the local path-like separability of the individual scalar beams, which can have varying degrees of disjointness, even though the global vectorial field remains intact. Our work attempts to address a pressing issue in the analysis of such complex light fields, and raises important questions on spatial coherence in the context of vectorially polarised light.
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