翻译 | 唐一尘

Nature，23 April 2020，Volume 580 Issue 7804

《自然》2020年4月23日，580卷，7804期

物理学与天文学

Physics and Astronomy

老舍简介及作品简介，Observation of topologically enabled unidirectional guided resonances

拓扑激活的单向引导共振的观察

▲ 作者：Xuefan Yin、Jicheng Jin、Bo Zhen，et al.

▲ 链接：

▲ 摘要

单向辐射对各种光电应用十分重要，如激光、光栅耦合器和光天线。然而，几乎所有现有的单向发射器都依赖于禁止发射波的材料或结构——也就是通常体积庞大、有损且难以制造的镜子。

在这里，研究人员从理论上提出并实验证明了光子晶体板中的一类共振现象，即便没有镜子，这些共振也只向平板的一侧辐射。这些共振被称为“单向引导共振”，当极化场中的一对半整数拓扑电荷在动量空间中相互碰撞时，它们就会出现。

威廉·华兹华斯（William Wordsworth，1770-1850年），英国浪漫主义诗人，曾当上桂冠诗人。其诗歌理论动摇了英国古典主义诗学的统治，有力地推动了英国诗歌的革新和浪漫主义运动的发展。他是文艺复兴运动以来最重要的英语诗人之一，。

研究人员通过实验证明了单向引导共振，实现了高达1.6×105的单边辐射质量因子。通过远场偏振测量进一步证明了它们的拓扑性质。该工作是将拓扑原理应用于光场控制的一个典型案例，可以用于高效光栅耦合器和天线。

▲ Abstract

The wide-binary origin of (2014) MU69-like Kuiper belt contact binaries

柯伊伯带“接触双星”的宽双星起源

▲ 作者：Evgeni Grishin、Uri Malamud、Christoph M. Schäfer ，et al.

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▲ 摘要

“新视野号”飞船飞越冥王星和冥卫二并首次成像后，访问了柯伊伯带天体“天涯海角”。成像显示这是一个低旋转周期（15.92小时）的接触双星，由窄颈连接的两个独立星球组成，并具有很高的倾角。“天涯海角”的性质与柯伊伯带其他接触双星相似。但人们目前仍不清楚这种双星系统的起源。

在这里，研究人员重现了“天涯海角”和其他类似的斜向接触双星的特征，它们是在任意高倾斜且低转速下缓慢融合成双星。研究人员模拟发现大约15%的具有余弦均匀倾角分布的超宽双星可能通过这个过程合并。

此外，研究人员发现这样的合并非常温和，仅轻微地改变了柯伊伯带天体的形状。该研究不仅解释了“天涯海角”的观测性质，而且也适用于柯伊伯带或小行星带其他双星以及太阳系内外的行星系统。

▲ Abstract

Following its flyby and first imaging of the Pluto–Charon binary，the New Horizons spacecraft visited the Kuiper belt object (KBO) 2014 MU69 (also known as (486958) Arrokoth). The imaging showed MU69 to be a contact binary that rotates at a low spin period (15.92 hours)，is made of two individual lobes connected by a narrow neck and has a high obliquity (about 98 degrees)，properties that are similar to those of other KBO contact binaries inferred through photometric observations. However，all scenarios suggested so far for the origins of such configurations have failed to reproduce these properties and their probable frequent occurrence in the Kuiper belt. Here we show that semi-secular perturbations operating on only ultrawide KBO binaries close to their stability limit can robustly lead to gentle，slow binary mergers at arbitrarily high obliquities but low rotational velocities，reproducing the characteristics of MU69 and other similar oblique contact binaries. Using N-body simulations，we find that approximately 15 per cent of all ultrawide binaries with a cosine-uniform inclination distribution are likely to merge through this process. Moreover，we find that such mergers are sufficiently gentle to deform the shape of the KBO only slightly. The semi-secular contact binary formation channel not only explains the observed properties of MU69，but may also apply to other Kuiper belt or asteroid belt binaries and in the Solar System and extra-solar moon systems.

大气科学/化学

Atmospheric Science/Chemistry

极端降雨引发了2018年基拉韦厄火山喷发

▲ 作者：Jamie I. Farquharson、Falk Amelung

2008年7月17日伦敦O2 Arena演出 ,在《Tower of Song》中, Cohen弹了一段比较俏皮的键盘SOLO , 台下人们不禁起哄 , 一脸慈爱的Cohen微笑回意:“u are very kind !”。 2008年 , 74岁的Cohen被经纪人兼情人卷走了他所有积蓄消。

▲ 链接：

▲ 摘要

已知降雨会触发地震活动和改变火山活动性。但是，有关这类效应的观察局限于火山浅地层，降雨是否会激活深层岩浆运动并未可知。基拉韦厄火山的喷发是复杂且多阶段的，但是其触发因素一直不甚明了。2018年5~8月，基拉韦厄火山周围出现裂缝，山顶发生爆裂喷发，火山口崩塌。

研究人员考察了降雨对2018年基拉韦厄火山喷发的影响。在火山喷发前，夏威夷有多个月出现了异常多的降雨。研究表明雨水渗透进火山地表下，使孔隙压力在火山喷发前夕和喷发期间上升到近50年最高水平。研究人员认为这削弱了火山的结构，使岩浆得以进入，进而引起火山喷发。

分级: 意大利:T 加拿大:PA 加拿大:A 加拿大:AA 加拿大:18 芬兰:K-18 美国:R 冰岛:16 阿根廷:16 澳大利亚:M 加拿大:13+ 加拿大:18A 加拿大:18A 智利:14 芬兰:K-16 法国:-12 德国:16 爱尔兰:15 以色列:PG 日本:R-15 荷兰。

他们还对基拉韦厄火山的历史喷发情况做了统计分析，发现从1790年开始，将近60%的喷发发生在雨季，不过喷发时间比旱季短。这表明降雨和基拉韦厄火山历史上的喷发存在关联。增强对降雨和火山喷发之间关系的理解，有望帮助预测未来的降雨诱发型火山活动。

▲ Abstract

The May 2018 rift intrusion and eruption of Kīlauea Volcano，Hawai‘i，represented one of its most extraordinary eruptive sequences in at least 200 years，yet the trigger mechanism remains elusive. The event was preceded by several months of anomalously high precipitation. It has been proposed that rainfall can modulate shallow volcanic activity，but it remains unknown whether it can have impacts at the greater depths associated with magma transport. Here we show that immediately before and during the eruption，infiltration of rainfall into Kīlauea Volcano’s subsurface increased pore pressure at depths of 1 to 3 kilometres by 0.1 to 1 kilopascals，to its highest pressure in almost 50 years. We propose that weakening and mechanical failure of the edifice was driven by changes in pore pressure within the rift zone，prompting opportunistic dyke intrusion and ultimately facilitating the eruption. A precipitation-induced eruption trigger is consistent with the lack of precursory summit inflation，showing that this intrusion—unlike others—was not caused by the forceful intrusion of new magma into the rift zone. Moreover，statistical analysis of historic eruption occurrence suggests that rainfall patterns contribute substantially to the timing and frequency of Kīlauea’s eruptions and intrusions. Thus，volcanic activity can be modulated by extreme rainfall triggering edifice rock failure—a factor that should be considered when assessing volcanic hazards. Notably，the increasingly extreme weather patterns associated with ongoing anthropogenic climate change could increase the potential for rainfall-triggered volcanic phenomena worldwide.

Accurate compound-specific 14C

dating of archaeological pottery vessels

陶器的精确14C年代测定

▲ 作者：Emmanuelle Casanova、Timothy D. J. Knowles、Richard P. Evershed，et al.

▲ 链接：

▲ 摘要

陶器是考古遗址最常见的人工制品之一，但是，对这些物件进行精确的放射性碳测年难度极大。古代陶器中常能发现食物残渣的脂肪成分，这些成分在前人烹饪时被粘土吸收或保存下来，或能作为放射性碳测年的另一个碳来源。

本论文报道了一种给古代陶器测年的新方法，该方法基于对脂肪酸形式的食物残渣进行分析。研究人员利用名为制备气相色谱法的技术，从陶器中提取出了棕榈酸和硬脂酸，再用加速器质谱法对这些残渣进行放射性碳测年。

▲ Abstract

Pottery is one of the most commonly recovered artefacts from archaeological sites. Despite more than a century of relative dating based on typology and seriation，accurate dating of pottery using the radiocarbon dating method has proven extremely challenging owing to the limited survival of organic temper and unreliability of visible residues. Here we report a method to directly date archaeological pottery based on accelerator mass spectrometry analysis of 14C in absorbed food residues using palmitic (C16:0 ) and stearic (C18:0 ) fatty acids purified by preparative gas chromatography. We present accurate compound-specific radiocarbon determinations of lipids extracted from pottery vessels，which were rigorously evaluated by comparison with dendrochronological dates and inclusion in site and regional chronologies that contained previously determined radiocarbon dates on other materials. Notably，the compound-specific dates from each of the C16:0 and C18:0 fatty acids in pottery vessels provide an internal quality control of the resultsand are entirely compatible with dates for other commonly dated materials. Accurate radiocarbon dating of pottery vessels can reveal: (1) the period of use of pottery; (2) the antiquity of organic residues，including when specific foodstuffs were exploited; (3) the chronology of sites in the absence of traditionally datable materials; and (4) direct verification of pottery typochronologies. Here we used the method to date the exploitation of dairy and carcass products in Neolithic vessels from Britain，Anatolia，central and western Europe，and Saharan Africa.

生态学Ecology

The projected timing of abrupt ecological disruption from climate change

气候变化对生态造成突然破坏的预计时间

▲ 作者：Christopher H. Trisos、Cory Merow、Alex L. Pigot

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▲ 摘要

本文评估了3万多种陆生生物和海洋生物当前的热生态位，并估算了它们可能会在何时经历前所未有的温度。

研究人员利用1850~2005年的年度气候模型数据，确定了30652种鸟类、哺乳动物、爬行动物、两栖动物、鱼类和其他海洋动植物经历过的平均最暖温度。

随后，他们利用最长到2100年的气候预估，推断全球100千米网格内的物种可能会在何时经历超过这些极限的温度，且持续至少5年时间。

研究人员预计，随着多个物种暴露在空前的温度下，这些生态组合可能会同时迎来生物多样性的突然破坏。在温室气体排放持续增加的气候变化场景下，热带海洋和热带雨林及高纬度地区预计将分别在2030年和2050年达到这种前所未有的温度状况。

▲ Abstract

主要内容：一天晚上，彼得·潘来到小姑娘温蒂家，教温蒂和她的两个弟弟在空中飞，并把他们带到了虚无岛。他们一到岛上，历险就连连不断。他们遇到了印第安人、海盗、美人鱼……由于海盗胡克的作祟，战争不断爆发，海岛无宁静。

As anthropogenic climate change continues the risks to biodiversity will increase over time，with future projections indicating that a potentially catastrophic loss of global biodiversity is on the horizon. However，our understanding of when and how abruptly this climate-driven disruption of biodiversity will occur is limited because biodiversity forecasts typically focus on individual snapshots of the future. Here we use annual projections (from 1850 to 2100) of temperature and precipitation across the ranges of more than 30，000 marine and terrestrial species to estimate the timing of their exposure to potentially dangerous climate conditions. We project that future disruption of ecological assemblages as a result of climate change will be abrupt，because within any given ecological assemblage the exposure of most species to climate conditions beyond their realized niche limits occurs almost simultaneously. Under a high-emissions scenario (representative concentration pathway (RCP) 8.5)，such abrupt exposure events begin before 2030 in tropical oceans and spread to tropical forests and higher latitudes by 2050. If global warming is kept below 2 °C，less than 2% of assemblages globally are projected to undergo abrupt exposure events of more than 20% of their constituent species; however，the risk accelerates with the magnitude of warming，threatening 15% of assemblages at 4 °C，with similar levels of risk in protected and unprotected areas. These results highlight the impending risk of sudden and severe biodiversity losses from climate change and provide a framework for predicting both when and where these events may occur.

Extant timetrees are consistent with a myriad of diversification histories

出生: 1965年7月31日，生于英国的格温特郡的Chipping Sodbury普通医院。父母： 父亲Peter是一名退休的飞机制造厂Rolls-Royce的管理人员，母亲Ann是一位实验室技术人员，于1990因病去逝，终年45岁。他们1963年在一列火车上一。

现存时间树与多样化历史一致

▲ 作者：Stilianos Louca、Matthew W. Pennell

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▲ 摘要

时间校准的现存物种（这里称为“现存时间树”）的系统发育被广泛用于估计物质多样化动态。然而，关于这些推论的可靠性有相当多的辩论，而且迄今为止，相关领域关键问题仍然没有解决。

在这里，研究人员澄清了在广义的出生—死亡模型下，可以从现存时间树中提取的精确信息，该模型是大多数现有估算方法的基础。

他们证明了，任何多样化情况都存在无穷多个可选的多样化情景，这些情景同样有可能产生现存的时间树。仅使用现有的时间树不可能区分这些“一致的”场景。重要的是，一致性多样化情景可以表现出明显的不同，这表明以前的许多研究可能过度解释了系统发育的证据。

因此，研究人员介绍了可识别和易于解释的变量，这些变量包含了关于过去多样化动态的所有可用信息，并演示了这些变量可以从现存的时间树进行估计。他们认为，测量和建模这些可识别的变量，提供了一个更稳健的方式研究历史多样化动态。而且，古生物学数据将继续是回答一些宏观进化问题的关键。

▲ Abstract

Time-calibrated phylogenies of extant species (referred to here as ‘extant timetrees’) are widely used for estimating diversification dynamics. However，there has been considerable debate surrounding the reliability of these inferences and，to date，this critical question remains unresolved. Here we clarify the precise information that can be extracted from extant timetrees under the generalized birth–death model，which underlies most existing methods of estimation. We prove that，for any diversification scenario，there exists an infinite number of alternative diversification scenarios that are equally likely to have generated any given extant timetree. These ‘congruent’ scenarios cannot possibly be distinguished using extant timetrees alone，even in the presence of infinite data. Importantly，congruent diversification scenarios can exhibit markedly different and yet similarly plausible dynamics，which suggests that many previous studies may have over-interpreted phylogenetic evidence. We introduce identifiable and easily interpretable variables that contain all available information about past diversification dynamics，and demonstrate that these can be estimated from extant timetrees. We suggest that measuring and modelling these identifiable variables offers a more robust way to study historical diversification dynamics. Our findings also make it clear that palaeontological data will continue to be crucial for answering some macroevolutionary questions.