編譯 | 馮維維
Nature, 30 April 2020, Volume 580 Issue 7805
《自然》2020年4月30日，第580卷，7805期
物理學Physics
Nightside condensation of iron in an ultrahot giant exoplanet
鐵元素在超熱巨大系外行星夜間凝結
▲ 作者：David Ehrenreich, Christophe Lovis, Filippo Zerbi, etc.
▲ 鏈接：https://www.nature.com/articles/s41586-020-2107-1
▲ 摘要
超熱的巨大系外行星接受的日照是地球的數千倍。它們的高溫環境是研究極端行星氣候和化學的理想實驗室。
作者報告了在超熱的外行星WASP-76b上探測到的非對稱大氣信號。他們使用高分散光譜學和一個大的光子收集區相結合的方法來解決這個信號。中性鐵的吸收信號在尾緣以每秒- 11±0.7公里的速度發生藍移，這可以用行星自轉和白天吹來的熱風的組合來解釋。
相反，靠近晨光明暗界線的一側沒有信號，表明鐵原子沒有吸收那裡的星光。作者由此得出結論，鐵在穿越該行星背面的過程中必然會凝結。
▲ Abstract
Ultrahot giant exoplanets receive thousands of times Earth’s insolation. Their high-temperature atmospheres are ideal laboratories for studying extreme planetary climates and chemistry. Here we report the detection of an asymmetric atmospheric signature in the ultrahot exoplanet WASP-76b. We spectrally and temporally resolve this signature using a combination of high-dispersion spectroscopy with a large photon-collecting area. The absorption signal, attributed to neutral iron, is blueshifted by −11 ± 0.7 kilometres per second on the trailing limb, which can be explained by a combination of planetary rotation and wind blowing from the hot dayside16. In contrast, no signal arises from the nightside close to the morning terminator, showing that atomic iron is not absorbing starlight there. We conclude that iron must therefore condense during its journey across the nightside.
Months-long thousand-kilometre-scale wobbling before great subduction earthquakes
大俯衝地震前長達數月的數千公里範圍的抖動
▲ 作者：Jonathan R. Bedford, Marcos Moreno, Zhiguo Deng, Onno Oncken, Bernd Schurr, Timm John, Juan Carlos Báez, Michael Bevis
▲ 鏈接：https://www.nature.com/articles/s41586-020-2212-1
▲ 摘要
大推力地震是造成一些最具破壞性的自然災害的原因。
作者使用一種最近開發的軌跡建模方法，該方法旨在將長期構造運動從每日GNSS時間序列中分離出來，來證明2010年智利的Maule地震（8.8級）和2011年日本的Tohoku-oki地震（9.0級）發生之前，地表位移發生了4~8毫米的逆轉，這種逆轉持續了幾個月，跨越了數千公里。
日本東北部大地震前發生的地表位移反轉模型顯示，菲律賓海板塊先是緩慢滑動，然後突然向下俯衝，其速度之快導致整個日本的粘彈性反彈。
因此，為了更好地理解即將發生的大地震，不僅要考慮板塊界面摩擦過程的演化，還要考慮深部俯衝過程的動態邊界條件，如亞穩態板塊的突然緻密化。
▲ Abstract
Megathrust earthquakes are responsible for some of the most devastating natural disasters. Here we use a recently developed trajectory modelling approach that is designed to isolate secular tectonic motions from the daily GNSS time series to show that the 2010 Maule, Chile (moment magnitude 8.8) and 2011 Tohoku-oki, Japan (moment magnitude 9.0) earthquakes were preceded by reversals of 4–8 millimetres in surface displacement that lasted several months and spanned thousands of kilometres. Modelling of the surface displacement reversal that occurred before the Tohoku-oki earthquake suggests an initial slow slip followed by a sudden pulldown of the Philippine Sea slab so rapid that it caused a viscoelastic rebound across the whole of Japan. Therefore, to understand better when large earthquakes are imminent, we must consider not only the evolution of plate interface frictional processes but also the dynamic boundary conditions from deeper subduction processes, such as sudden densification of metastable slab.
Exploring dynamical phase transitions with cold atoms in an optical cavity
光腔中冷原子的動態相變
▲ 作者：Juan A. Muniz, Diego Barberena, Robert J. Lewis-Swan, Dylan J. Young, Julia R. K. Cline, Ana Maria Rey & James K. Thompson
▲ 鏈接：https://www.nature.com/articles/s41586-020-2224-x
▲ 摘要
光腔中原子和光的相互作用為研究受控環境下的集體（多體）量子物理提供了一種手段。
作者在一個光學腔中使用大約一百萬個鍶-88原子的集合來模擬一個集體Lipkin-Meshkov-Glick（LMG）模型，這是量子磁性的一個標誌性模型，並報告了在這個系統中觀察到的不同的物質動力學階段。該系統允許作者探索動態相變對系統大小、初始狀態和其他參數的依賴關係。
這些觀測結果可以與相關係統中類似的動力學相聯繫起來，包括超流氦中的約瑟夫森效應，或原子與固體耦合的極化激元凝聚。該系統本身提供了在光學躍遷中產生在計量上有用的糾纏態的可能性，這可能允許在最先進的原子鐘中進行量子增強。
▲ Abstract
Interactions between atoms and light in optical cavities provide a means of investigating collective (many-body) quantum physics in controlled environments. Here, we use an ensemble of about a million strontium-88 atoms in an optical cavity to simulate a collective Lipkin–Meshkov–Glick model, an iconic model in quantum magnetism, and report the observation of distinct dynamical phases of matter in this system. Our system allows us to probe the dependence of dynamical phase transitions on system size, initial state and other parameters. These observations can be linked to similar dynamical phases in related systems, including the Josephson effect in superfluid helium, or coupled atomic and solid-state polariton condensates. The system itself offers potential for generation of metrologically useful entangled states in optical transitions, which could permit quantum enhancement in state-of-the-art atomic clocks.
醫學Medicine
An open-source drug discovery platform enables ultra-large virtual screens
開源藥物發現平臺可實現超大虛擬試驗
▲ 作者：Christoph Gorgulla, Andras Boeszoermenyi, Zi-Fu Wang, Haribabu Arthanari, etc.
▲ 鏈接：https://www.nature.com/articles/s41586-020-2117-z
▲ 摘要
目前，批准一種藥物的平均成本為20億~ 30億美元，研發時間超過10年。在某種程度上，這是由於臨床（前）階段昂貴和耗時的溼實驗、糟糕的初始對應化合物和高磨耗率。
作者描述了高度自動化和通用的開源平臺VirtualFlow，它具有完美的縮放行為，能夠有效地篩選超大型化合物庫。VirtualFlow能夠使用各種最強大的擴展程序。
通過使用VirtualFlow，作者準備了一個最大且免費可用的現成的配體庫，其中有超過14億個商業可用的分子。為了證明VirtualFlow的強大功能，作者篩選了超過10億個化合物，並識別出一組結構多樣的分子，它們與亞微摩爾親和力的KEAP1結合。
其中一種先導抑制劑與納米級親和的KEAP1結合，干擾KEAP1與轉錄因子NRF2之間的相互作用。這說明了VirtualFlow的潛力，它可以訪問化學空間的廣大區域，並識別與目標蛋白具有高親和力的分子。
▲ Abstract
On average, an approved drug currently costs US$2–3 billion and takes more than 10 years to develop. In part, this is due to expensive and time-consuming wet-laboratory experiments, poor initial hit compounds and the high attrition rates in the (pre-)clinical phases. Here we describe VirtualFlow, a highly automated and versatile open-source platform with perfect scaling behaviour that is able to prepare and efficiently screen ultra-large libraries of compounds. VirtualFlow is able to use a variety of the most powerful docking programs. Using VirtualFlow, we prepared one of the largest and freely available ready-to-dock ligand libraries, with more than 1.4 billion commercially available molecules. To demonstrate the power of VirtualFlow, we screened more than 1 billion compounds and identified a set of structurally diverse molecules that bind to KEAP1 with submicromolar affinity. One of the lead inhibitors engages KEAP1 with nanomolar affinity and disrupts the interaction between KEAP1 and the transcription factor NRF2. This illustrates the potential of VirtualFlow to access vast regions of the chemical space and identify molecules that bind with high affinity to target proteins.
Action of a minimal contractile bactericidal nanomachine
最小收縮殺菌納米機器的作用
▲ 作者：Peng Ge, Dean Scholl, Nikolai S. Prokhorov, Z. Hong Zhou, etc.
▲ 鏈接：https://www.nature.com/articles/s41586-020-2186-z
▲ 摘要
R型細菌素是最小可收縮的納米機器，有望成為精確的抗生素。作者報告了完整的R2 綠膿桿菌素的收縮前和收縮後狀態的原子模型，每個包含10個基因產物的11個獨特原子模型的384個亞基。
這些結構的比較表明，綠膿桿菌素收縮期間會發生一系列事件：尾纖維觸發基板三叢的橫向分離；然後引發一系列事件導致鞘收縮；這種收縮將化學能轉化為機械力，推動鐵頭管穿過細菌細胞表面，殺死細菌。
▲ Abstract
R-type bacteriocins are minimal contractile nanomachines that hold promise as precision antibiotics. Here we report the atomic model of the complete R2 pyocin in its pre-contraction and post-contraction states, each containing 384 subunits of 11 unique atomic models of 10 gene products. Comparison of these structures suggests the following sequence of events during pyocin contraction: tail fibres trigger lateral dissociation of baseplate triplexes; the dissociation then initiates a cascade of events leading to sheath contraction; and this contraction converts chemical energy into mechanical force to drive the iron-tipped tube across the bacterial cell surface, killing the bacterium.
教育Education
Measuring and forecasting progress towards the education-related SDG targets
衡量和預測教育相關的可持續發展目標的進展
▲ 作者：Joseph Friedman, Hunter York, Nicholas Graetz, Lauren Woyczynski, Joanna Whisnant, Simon I. Hay, Emmanuela Gakidou, etc.
▲ 鏈接：https://www.nature.com/articles/s41586-020-2198-8
▲ 摘要
教育是幸福的一個關鍵方面，是發展的一個關鍵指標。可持續發展目標（SDGs）優先考慮教育方面的進展，並將新的重點放在不平等問題上。
作者對一些國家的教育年限分佈進行了建模，並使用該模型探索自1970年以來的教育不平等，並預測實現與教育相關的2030年可持續發展目標的進展。
作者分析表明，儘管世界在很大程度上有望在2030年前實現基本普及的初等教育，但中等和高等教育的完成率仍面臨巨大挑戰。
從全球看，到2018年，上學方面的性別差距已接近消除，但在撒哈拉以南非洲、北非和中東的部分地區，性別差異依然嚴重。據預測，到2030年，18個國家的女性受教育程度將顯著高於男性。全球範圍內的教育不平等在2017年達到頂峰，預計到2030年將穩步下降。
▲ Abstract
Education is a key dimension of well-being and a crucial indicator of development. The Sustainable Development Goals (SDGs) prioritize progress in education, with a new focus on inequality. Here we model the within-country distribution of years of schooling, and use this model to explore educational inequality since 1970 and to forecast progress towards the education-related 2030 SDG targets. We show that although the world is largely on track to achieve near-universal primary education by 2030, substantial challenges remain in the completion rates for secondary and tertiary education. Globally, the gender gap in schooling had nearly closed by 2018 but gender disparities remained acute in parts of sub-Saharan Africa, and North Africa and the Middle East. It is predicted that, by 2030, females will have achieved significantly higher educational attainment than males in 18 countries. Inequality in education reached a peak globally in 2017 and is projected to decrease steadily up to 2030.
