《自然》（20240418出版）一周論文導讀

原文地址：http://news.sciencenet.cn/htmlnews/2024/4/521227.shtm

編譯 | 馮維維

Nature,  Volume 628 Issue 8008, 18 April 2024

《自然》,第628卷，8008期，2024年4月18日

物理學Physics

Methane emission from a cool brown dwarf

一顆低溫褐矮星釋放出的甲烷

▲ 作者：Jacqueline K. Faherty, Ben Burningham, Jonathan Gagné, Genaro Suárez, Johanna M. Vos, Sherelyn Alejandro Merchan, Caroline V. Morley, Melanie Rowland, Brianna Lacy, Rocio Kiman, Dan Caselden, J. Davy Kirkpatrick, Aaron Meisner, Adam C. Schneider, Marc Jason Kuchner, Daniella Carolina Bardalez Gagliuffi, Charles Beichman, Peter Eisenhardt, Christopher R. Gelino, Ehsan Gharib-Nezhad, Eileen Gonzales, Federico Marocco, Austin James Rothermich & Niall Whiteford

▲ 鏈接：

https://www.nature.com/articles/s41586-024-07190-w

▲ 摘要：

在太陽系之外，極光是從對孤立的褐矮星的無線電觀測中推斷出來的。在太陽系中，巨大的行星在電磁波譜上有極光發射的特征，包括H3+和甲烷的紅外發射。科學家嘗試在無線電中尋找具有極光特征的孤立的褐矮星，以尋找相應的紅外特征，但只報道了無效探測。CWISEP j193518.59 - 154620.3.（簡稱W1935）是一顆孤立的褐矮星，溫度約為482 K。

研究者報告了詹姆斯·韋布太空望遠鏡觀測到W1935在3.326 μm波段強烈的甲烷排放。大氣模擬得出的結論表示，以1-10毫巴為中心的大約300 K的逆溫重復了這一特征。這代表了沒有主星輻射的類木星大氣的大氣溫度反演。

強逆溫的一個合理解釋是由極光過程加熱，盡管不能排除其他內部和外部動力過程。最合適的模型排除了H3+的貢獻，這在太陽系氣體巨星中很突出。然而，這與H3+在W1935發射源的較高壓力下的快速破壞是一致的。

▲ Abstract：

Beyond our Solar System, aurorae have been inferred from radio observations of isolated brown dwarfs. Within our Solar System, giant planets have auroral emission with signatures across the electromagnetic spectrum including infrared emission of H3+ and methane. Isolated brown dwarfs with auroral signatures in the radio have been searched for corresponding infrared features, but only null detections have been reported. CWISEP J193518.59-154620.3. (W1935 for short) is an isolated brown dwarf with a temperature of approximately 482?K. Here we report James Webb Space Telescope observations of strong methane emission from W1935 at 3.326?μm. Atmospheric modelling leads us to conclude that a temperature inversion of approximately 300?K centred at 1–10?mbar replicates the feature. This represents an atmospheric temperature inversion for a Jupiter-like atmosphere without irradiation from a host star. A plausible explanation for the strong inversion is heating by auroral processes, although other internal and external dynamical processes cannot be ruled out. The best-fitting model rules out the contribution of H3+ emission, which is prominent in Solar System gas giants. However, this is consistent with rapid destruction of H3+ at the higher pressure where the W1935 emission originates.

A hybrid topological quantum state in an elemental solid

單質固體中的混合拓撲量子態

▲ 作者：Md Shafayat Hossain, Frank Schindler, Rajibul Islam, Zahir Muhammad, Yu-Xiao Jiang, Zi-Jia Cheng, Qi Zhang, Tao Hou, Hongyu Chen, Maksim Litskevich, Brian Casas, Jia-Xin Yin, Tyler A. Cochran, Mohammad Yahyavi, Xian P. Yang, Luis Balicas, Guoqing Chang, Weisheng Zhao, Titus Neupert & M. Zahid Hasan

▲ 鏈接：

https://www.nature.com/articles/s41586-024-07203-8

▲ 摘要：

拓撲學和相互作用是現代量子物質理解中的基本概念。它們之間的聯系產生了三個重要的研究方向：

（1）不同相互作用之間的競爭，如在幾個相互交織的相中；（2）相互作用和拓撲之間的相互作用驅動扭曲層狀材料和拓撲磁體中的現象；（3）幾個拓撲順序的合并產生不同的新相。前兩個例子已經發展成為主要的研究領域，盡管最后一個例子仍未被探索，主要是因為缺乏實驗研究的材料平臺。

研究者使用隧道顯微鏡、光電發射光譜和理論分析，揭示了簡單元素-固體砷中物質的“混合”拓撲相。通過獨特的體積-表面-邊緣對應，他們發現砷具有連接強的高階拓撲結構，穩定了混合拓撲相。雖然動量-空間光譜測量顯示了拓撲表面狀態的跡象，但實空間顯微鏡測量揭示了表面上各種天然納米結構上拓撲誘導的階梯邊緣傳導通道的獨特幾何形狀。

利用理論模型，他們證明了砷中無間隙階邊態的存在依賴于非平凡強Z2不變量和非平凡高階拓撲不變量的同時存在，這為混合拓撲的存在提供了實驗證據。研究強調了在工程量子或納米器件中探索不同帶拓撲的相互作用和利用相關拓撲傳導通道的途徑。

▲ Abstract：

Topology and interactions are foundational concepts in the modern understanding of quantum matter. Their nexus yields three important research directions: (1) the competition between distinct interactions, as in several intertwined phases, (2) the interplay between interactions and topology that drives the phenomena in twisted layered materials and topological magnets, and (3) the coalescence of several topological orders to generate distinct novel phases. The first two examples have grown into major areas of research, although the last example remains mostly unexplored, mainly because of the lack of a material platform for experimental studies. Here, using tunnelling microscopy, photoemission spectroscopy and a theoretical analysis, we unveil a ‘hybrid’ topological phase of matter in the simple elemental-solid arsenic. Through a unique bulk-surface-edge correspondence, we uncover that arsenic features a conjoined strong and higher-order topology that stabilizes a hybrid topological phase. Although momentum-space spectroscopy measurements show signs of topological surface states, real-space microscopy measurements unravel a unique geometry of topologically induced step-edge conduction channels revealed on various natural nanostructures on the surface. Using theoretical models, we show that the existence of gapless step-edge states in arsenic relies on the simultaneous presence of both a non-trivial strong Z2 invariant and a non-trivial higher-order topological invariant, which provide experimental evidence for hybrid topology. Our study highlights pathways for exploring the interplay of different band topologies and harnessing the associated topological conduction channels in engineered quantum or nano-devices.

Phononic switching of magnetization by the ultrafast Barnett effect

利用超快巴尼特效應實現磁化的聲子開關

▲ 作者：C. S. Davies, F. G. N. Fennema, A. Tsukamoto, I. Razdolski, A. V. Kimel & A. Kirilyuk

▲ 鏈接：

https://www.nature.com/articles/s41586-024-07200-x

▲ 摘要：

歷史上的巴內特效應描述了一個凈磁矩為零的慣性體如何在機械旋轉時獲得自發磁化。最近的突破性實驗表明，超短激光脈沖在數百飛秒內破壞有序鐵磁體的磁化，自旋失去角動量，成為圓偏振光學聲子，這是超快愛因斯坦-德哈斯效應的一部分。

然而，利用這種晶格的高頻振動來在附近的磁性介質中往復切換磁化的前景尚未得到實驗探索。

研究者證明了通過超快巴尼特效應獲得的自發磁化，通過順磁性襯底中的圓極化光學聲子的共振激發，可以用來永久地逆轉安裝在所述襯底上的異質結構的磁性狀態。由于聲子的手性控制磁開關的方向，超快巴尼特效應為對磁有序進行超快非局部控制提供了一種選擇性和潛在的通用方法。

▲ Abstract：

The historic Barnett effect describes how an inertial body with otherwise zero net magnetic moment acquires spontaneous magnetization when mechanically spinning. Breakthrough experiments have recently shown that an ultrashort laser pulse destroys the magnetization of an ordered ferromagnet within hundreds of femtoseconds, with the spins losing angular momentum to circularly polarized optical phonons as part of the ultrafast Einstein–de Haas effect. However, the prospect of using such high-frequency vibrations of the lattice to reciprocally switch magnetization in a nearby magnetic medium has not yet been experimentally explored. Here we show that the spontaneous magnetization gained temporarily by means of the ultrafast Barnett effect, through the resonant excitation of circularly polarized optical phonons in a paramagnetic substrate, can be used to permanently reverse the magnetic state of a heterostructure mounted atop the said substrate. With the handedness of the phonons steering the direction of magnetic switching, the ultrafast Barnett effect offers a selective and potentially universal method for exercising ultrafast non-local control over magnetic order.

氣候和生態Climate & Ecology

The economic commitment of climate change

氣候變化讓全球收入減少

▲ 作者：Maximilian Kotz, Anders Levermann & Leonie Wenz

▲ 鏈接：https://www.nature.com/articles/s41586-024-07219-0

▲ 摘要：

宏觀經濟氣候變化損害的全球預測，通常會考慮長期平均年和全國氣溫的影響。研究者利用過去40年全球1600多個地區的最新實證研究結果，預測了溫度和降水造成的次國家損害，包括日變率和極端事件。

通過實證方法，他們發現世界經濟將在未來26年內減少19%的收入，而不受未來排放選擇的影響（相對于不受氣候影響的基線，考慮到物理氣候和經驗不確定性，可能范圍為11%~29%）。

在這個短期框架內，這些損失已經超過了將全球變暖限制在2℃以內所需的減緩成本的6倍，并且此后會因排放選擇而出現很大差異。造成的損害主要是通過平均溫度的變化引起的，但考慮到進一步的氣候因素，估計結果將提高約50%，并導致更強的區域異質性。

除極高緯度地區外，預計所有地區都將出現承諾損失，在極高緯度地區，溫度變率的減少會帶來好處。最大的損失發生在歷史累積排放量較低和當前收入較低的低緯度地區。

▲ Abstract：

Global projections of macroeconomic climate-change damages typically consider impacts from average annual and national temperatures over long time horizons. Here we use recent empirical findings from more than 1,600 regions worldwide over the past 40?years to project sub-national damages from temperature and precipitation, including daily variability and extremes. Using an empirical approach that provides a robust lower bound on the persistence of impacts on economic growth, we find that the world economy is committed to an income reduction of 19% within the next 26?years independent of future emission choices (relative to a baseline without climate impacts, likely range of 11–29% accounting for physical climate and empirical uncertainty). These damages already outweigh the mitigation costs required to limit global warming to 2?°C by sixfold over this near-term time frame and thereafter diverge strongly dependent on emission choices. Committed damages arise predominantly through changes in average temperature, but accounting for further climatic components raises estimates by approximately 50% and leads to stronger regional heterogeneity. Committed losses are projected for all regions except those at very high latitudes, at which reductions in temperature variability bring benefits. The largest losses are committed at lower latitudes in regions with lower cumulative historical emissions and lower present-day income.

FSC-certified forest management benefits large mammals compared to non-FSC

FSC森林有利于保護大型哺乳動物

▲ 作者：Joeri A. Zwerts, E. H. M. Sterck, Pita A. Verweij, Fiona Maisels, Jaap van der Waarde, Emma A. M. Geelen, Georges Belmond Tchoumba, Hermann Frankie Donfouet Zebaze & Marijke van Kuijk

▲ 鏈接：

https://www.nature.com/articles/s41586-024-07257-8

▲ 摘要：

世界上超過四分之一的熱帶森林被用來采伐木材。伐木影響了這些生態系統的生物多樣性，主要是通過開辟森林道路，方便在廣大地區狩獵野生動物。森林管理委員會（FSC）等森林管理認證計劃有望減輕對生物多樣性的影響，但由于研究設計方面的挑戰，主要是樣本量有限，迄今為止對FSC認證的有效性知之甚少。

研究者通過在西赤道非洲的14個伐木區使用130萬張相機陷阱拍攝的55種哺乳動物的照片來提供這一證據。他們觀察到，在FSC認證的伐木特許權中，遇到哺乳動物的比率高于非FSC伐木特許權。

對于體重超過10公斤的物種和高度保護的物種，如極度瀕危的森林象和西部低地大猩猩，這種影響最為明顯。在整個哺乳動物群落中，與FSC認證的特許權相比，非FSC特許權含有更多的嚙齒動物和其他小物種。

物種保護的首要任務應該是通過有效的執法來維持未采伐的森林，但對于采伐的森林，研究結果提供了令人信服的數據，即FSC認證的森林管理對哺乳動物群落的損害小于非FSC森林管理。這項研究提供了強有力的證據，證明FSC認證的森林管理或同等嚴格的要求和控制機制應該成為木材開采的規范，以避免由嚙齒動物和其他小物種主導的半空森林。

▲ Abstract：

More than a quarter of the world’s tropical forests are exploited for timber. Logging impacts biodiversity in these ecosystems, primarily through the creation of forest roads that facilitate hunting for wildlife over extensive areas. Forest management certification schemes such as the Forest Stewardship Council (FSC) are expected to mitigate impacts on biodiversity, but so far very little is known about the effectiveness of FSC certification because of research design challenges, predominantly limited sample sizes. Here we provide this evidence by using 1.3?million camera-trap photos of 55 mammal species in 14 logging concessions in western equatorial Africa. We observed higher mammal encounter rates in FSC-certified than in non-FSC logging concessions. The effect was most pronounced for species weighing more than 10?kg and for species of high conservation priority such as the critically endangered forest elephant and western lowland gorilla. Across the whole mammal community, non-FSC concessions contained proportionally more rodents and other small species than did FSC-certified concessions. The first priority for species protection should be to maintain unlogged forests with effective law enforcement, but for logged forests our findings provide convincing data that FSC-certified forest management is less damaging to the mammal community than is non-FSC forest management. This study provides strong evidence that FSC-certified forest management or equivalently stringent requirements and controlling mechanisms should become the norm for timber extraction to avoid half-empty forests dominated by rodents and other small species.

古生物學Paleontology

Jurassic shuotheriids show earliest dental diversification of mammaliaforms

侏羅紀shuotheriids顯示哺乳動物中最早的牙齒多樣化

▲ 作者：Fangyuan Mao, Zhiyu Li, Zhili Wang, Chi Zhang, Thomas Rich, Patricia Vickers-Rich & Jin Meng

▲ 鏈接：

https://www.nature.com/articles/s41586-024-07258-7

▲ 摘要：

侏羅紀時期的類哺乳動物Shuotheriids因其獨特的牙齒特征而困擾著科學家。shuotheriids有所謂的“假摩擦牙”，在下臼齒的三角狀體前面有一個“假爪狀體”（一種盆狀結構），這與目前在哺乳動物中看到的摩擦牙不同，爪狀體位于三角狀體后面。這種獨特的牙齒模式阻礙了人們對shuotheriid關系的理解以及哺乳動物物種進化的第一步。

研究小組使用先進的技術發現了侏羅紀shuotheriids的新標本，其中一些具有完整的骨骼，從而能夠徹底檢查它們的“假摩擦”牙齒。在對這種新材料的分析中，研究人員能夠使用各種分析方法更全面地分析牙齒結構，這表明shuotheriid牙齒結構似乎與docodontans的牙齒結構非常相似。

這項研究表明，shuotheriids在它們的底部牙齒中沒有真正的三角體，這表明它們與docodontans的關系比以前認為的更近。對牙齒結構的重新評估不僅解決了未解決的解釋，還引發了對哺乳動物形態進化關系的重新思考。

▲ Abstract：

Shuotheriids are Jurassic mammaliaforms that possess pseudotribosphenic teeth in which a pseudotalonid is anterior to the trigonid in the lower molar, contrasting with the tribosphenic pattern of therian mammals (placentals, marsupials and kin) in which the talonid is posterior to the trigonid. The origin of the pseudotribosphenic teeth remains unclear, obscuring our perception of shuotheriid affinities and the early evolution of mammaliaforms. Here we report a new Jurassic shuotheriid represented by two skeletal specimens. Their complete pseudotribosphenic dentitions allow reidentification of dental structures using serial homology and the tooth occlusal relationship. Contrary to the conventional view, our findings show that dental structures of shuotheriids can be homologized to those of docodontans and partly support homologous statements for some dental structures between docodontans and other mammaliaforms. The phylogenetic analysis based on new evidence removes shuotheriids from the tribosphenic ausktribosphenids (including monotremes) and clusters them with docodontans to form a new clade, Docodontiformes, that is characterized by pseudotribosphenic features. In the phylogeny, docodontiforms and ‘holotherians’ (Kuehneotherium, monotremes and therians)13 evolve independently from a Morganucodon-like ancestor with triconodont molars by labio-lingual widening their posterior teeth for more efficient food processing. The pseudotribosphenic pattern passed a cusp semitriangulation stage9, whereas the tribosphenic pattern and its precursor went through a stage of cusp triangulation. The two different processes resulted in complex tooth structures and occlusal patterns that elucidate the earliest diversification of mammaliaforms.

Fossils document evolutionary changes of jaw joint to mammalian middle ear

化石記錄了哺乳動物下頜關節到中耳的進化變化

▲ 作者：Fangyuan Mao, Chi Zhang, Jicheng Ren, Tao Wang, Guofu Wang, Fakui Zhang, Thomas Rich, Patricia Vickers-Rich & Jin Meng

▲ 鏈接：

https://www.nature.com/articles/s41586-024-07235-0

▲ 摘要：

長齒鯊雙頜關節由牙鱗關節外側和關節-方關節內側組成。關節-方關節及其相關的牙后骨構成哺乳動物中耳的前體。記錄從這種前體到哺乳動物中耳過渡的化石很少，導致對哺乳動物進化最早階段這一標志性器官的解釋不一致。

研究者報告了兩種侏羅紀哺乳動物的下頜中耳：一種新的morganucodondon 樣種和一種Shuotheriid水生動物。Morganucodonan樣種顯示出許多以前未知的后牙狀骨形態，并顯示出其關節-方關節喪失承重功能的特征。Shuotheriid的中耳接近哺乳動物的狀態，因為它的特征只適合于聽覺功能，盡管后牙骨仍然附著在牙上。

隨著下頜關節骨的縮小，兩種哺乳動物的方骨相對于關節有不同程度的內移。這些變化提供了證據，證明關節-方顎關節的承重功能逐漸喪失，這是哺乳動物進化過程中牙髓后骨脫離牙髓和Meckel軟骨最終破裂的先決條件。

▲ Abstract：