Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular "reactive oxygen species" (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation. We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation). The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible. This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference

The privatization of public housing arrangements in Hong Kong: an analysis of modern modes of goverance

published_or_final_versionPublic AdministrationMasterMaster of Public Administratio

Bleeding post-transplantation intrarenal pseudoaneurysms

We herein present a case of an intrarenal pseudoaneurysm developing 2 weeks after renal transplantation. The patient presented with hemorrhagic shock. Computed tomography confirmed an intrarenal pseudoaneurysm with extravasation of contrast and a large surrounding hematoma. Angiography confirmed the pseudoaneurysm, and embolization of the segmental graft renal artery was performed. In view of the uncertain etiology and the possibility of a mycotic pseudoaneurysm, we administered empiric antimicrobial therapy. The clinical course, investigations, and management are described. Finally, a review of the literature regarding post-transplantation pseudoaneurysms is presented. 以下是一宗於移植後 2 週出現的腎內僞動脈瘤個案，患者以出血性休克表現。當時為其安排緊急電腦斷層攝影 (CT)，發現有一個腎內僞動脈瘤，並呈現顯影劑溢出現象，且被一大型血腫圍繞。緊急血管攝影證實為植入腎之僞動脈瘤，同時我們對涉及的節段性動脈予以栓塞處置。基於病因並不明確，而且不能排除黴菌性僞動脈瘤的可能性，因此我們實施了經驗性抗微生物學療法。在本文中，我們描述了本個案的臨床歷程、相關檢查及後續處置，並指出我們在治療上所遭遇到的困難。最後，我們對移植後僞動脈瘤的相關文獻作出了回顧