編譯|未玖

Nature, 2 January 2025, Volume 637, Issue 8044

《自然》2025年1月2日，自然周論第637卷，出版8044期

天文學Astronomy

Magnetospheric origin of a fast radio burst constrained using scintillation

用“閃爍”約束的文導聞科快速射電暴磁層起源

▲ 作者：Kenzie Nimmo, Ziggy Pleunis, Paz Beniamini, Pawan Kumar, Adam E. Lanman, D. Z. Li, et al.

▲鏈接：

https://www.nature.com/articles/s41586-024-08297-w

▲摘要：

快速射電暴（FRBs）是一種持續時間在微秒到毫秒之間的射電瞬變現象，主要來自河外距離。讀新FRB的學網發射機制仍有爭議，主要有兩種相互競爭的自然周論模型：發生在靠近中央引擎的物理過程；以及傳播到大徑向距離的相對論性激波。這兩種模型的出版預期發射區域大小有顯著差異。

研究組提出了FRB 20221022A頻譜中兩個相互相干閃爍尺度的文導聞科測量：一個源自位于銀河系內的散射屏，第二個源自其宿主星系或局部環境。讀新使用散射介質作為天體物理透鏡，學網可將觀測到的自然周論FRB橫向發射區域的規模限制在≤3×104千米。

這種發射尺寸與大徑向距離模型的出版預期不一致，更自然的文導聞科解釋是在中心致密天體的磁層內或磁層外發生了發射過程。最近，讀新人們發現FRB 20221022A呈現S形偏振角擺動，學網極有可能源自磁層發射過程。

這項工作中提出的閃爍結果獨立支持這一結論，同時強調閃爍是人們理解FRB發射物理及其宿主星系的有用工具。

▲ Abstract：

Fast radio bursts (FRBs) are microsecond-to-millisecond-duration radio transients that originate mostly from extragalactic distances. The FRB emission mechanism remains debated, with two main competing classes of models: physical processes that occur within close proximity to a central engine; and relativistic shocks that propagate out to large radial distances. The expected emission-region sizes are notably different between these two types of models. Here we present the measurement of two mutually coherent scintillation scales in the frequency spectrum of FRB?20221022A: one originating from a scattering screen located within the Milky Way, and the second originating from its host galaxy or local environment. We use the scattering media as an astrophysical lens to constrain the size of the observed FRB lateral emission region to ?3×104kilometres. This emission size is inconsistent with the expectation for the large-radial-distance models, and is more naturally explained by an emission process that operates within or just beyond the magnetosphere of a central compact object. Recently, FRB?20221022A was found to exhibit an S-shaped polarization angle swing, most likely originating from a magnetospheric emission process. The scintillation results presented in this work independently support this conclusion, while highlighting scintillation as a useful tool in our understanding of FRB emission physics and progenitors.

材料科學Materials Science

GaAs nano-ridge laser diodes fully fabricated in a 300-mm CMOS pilot line

300 mm CMOS試產線上全制造的砷化鎵納米脊激光二極管

▲ 作者：Yannick De Koninck, Charles Caer, Didit Yudistira, Marina Baryshnikova, Huseyin Sar, Ping-Yi Hsieh, et al.

▲鏈接：

https://www.nature.com/articles/s41586-024-08364-2

▲摘要：

硅光子學是一項快速發展的技術，有望徹底改變人們溝通、計算和感知世界的方式。然而，缺乏高可擴展性的原生互補金屬氧化物半導體（CMOS）集成光源是阻礙其廣泛采用的主要因素之一。盡管III-V族光源在硅上的混合和異質集成取得了相當大的進展，但III-V族材料的直接外延單片集成仍是具有最佳成本效益的片上光源。

研究組報道了基于納米脊工程的新集成方法，在CMOS試產線上，在300 mm硅晶圓上完全制造了電驅動砷化鎵（GaAs）基激光二極管。嵌入p-i-n二極管和InGaAs量子阱的GaAs納米脊波導在晶圓尺度上高質量生長。在晶圓上的300多個器件中，室溫連續波激光的波長約為1020 nm，閾值電流低至5 mA，輸出功率超過1 mW，激光線寬低至46 MHz，激光工作溫度高達55℃。

這些結果表明了III-V/Si納米脊工程概念在硅光子學平臺中單片集成激光二極管的潛力，有望實現光學傳感、互連等領域的成本敏感型大批量應用。

▲ Abstract：

Silicon photonics is a rapidly developing technology that promises to revolutionize the way we communicate, compute and sense the world. However, the lack of highly scalable, native complementary metal–oxide–semiconductor (CMOS)-integrated light sources is one of the main factors hampering its widespread adoption. Despite considerable progress in hybrid and heterogeneous integration of III–V light sources on silicon, monolithic integration by direct epitaxy of III–V materials remains the pinnacle of cost-effective on-chip light sources. Here we report the electrically driven gallium arsenide (GaAs)-based laser diodes fully fabricated on 300-mm Si wafers in a CMOS pilot manufacturing line based on a new integration approach, nano-ridge engineering. GaAs nano-ridge waveguides with embedded p–i–n diodes and InGaAs quantum wells are grown at high quality on a wafer scale. Room-temperature continuous-wave lasing is demonstrated at wavelengths around 1,020?nm in more than 300 devices across a wafer, with threshold currents as low as 5?mA, output powers beyond 1?mW, laser linewidths down to 46?MHz and laser operation up to 55?°C. These results illustrate the potential of the III–V/Si nano-ridge engineering concept for the monolithic integration of laser diodes in a Si photonics platform, enabling future cost-sensitive high-volume applications in optical sensing, interconnects and beyond.

Upconverting microgauges reveal intraluminal force dynamics in vivo

上轉換微測量儀揭示活體管腔內的力動態

▲ 作者：Jason R. Casar, Claire A. McLellan, Cindy Shi, Ariel Stiber, Alice Lay, Chris Siefe, et al.

▲鏈接：

https://www.nature.com/articles/s41586-024-08331-x

▲摘要：

肌肉細胞中動作電位產生的力將血液、食物和廢物運送到全身的管腔結構。雖然存在無創電生理技術，但大多數機械傳感器無法無創進入管腔結構。

研究組介紹了無毒的可攝入式機械傳感器，以實現管腔力的定量研究，并將其應用于研究活體秀麗隱桿線蟲的攝食。這些光學“微測量儀”由嵌入上轉換NaY0.8Yb0.18Er0.02F4@NaYF4納米顆粒的聚苯乙烯微球組成。結合光學顯微鏡和原子力顯微鏡在體外研究的微測量儀，他們發現力引起發射紅光和綠光比率的線性和無遲滯變化。

通過熒光成像和無創電生理學分析，研究組發現成年秀麗隱桿線蟲在進食過程中產生10μN左右的咬合力，并且咬合力產生的時間模式與進食器官的肌肉活動一致。此外，研究組測量的咬合力與用于分解蟲體細菌食物的壓力范圍內的赫茲接觸應力一致。

微測量儀有望進行定量研究，以探索該器官和其他管腔器官中神經肌肉壓力如何受到衰老、基因突變和藥物治療的影響。

▲ Abstract：

The forces generated by action potentials in muscle cells shuttle blood, food and waste products throughout the luminal structures of the body. Although non-invasive electrophysiological techniques exist, most mechanosensors cannot access luminal structures non-invasively. Here we introduce non-toxic ingestible mechanosensors to enable the quantitative study of luminal forces and apply them to study feeding in living Caenorhabditis elegans roundworms. These optical ‘microgauges’ comprise upconverting NaY0.8Yb0.18Er0.02F4@NaYF4nanoparticles embedded in polystyrene microspheres. Combining optical microscopy and atomic force microscopy to study microgauges in vitro, we show that force evokes a linear and hysteresis-free change in the ratio of emitted red to green light. With fluorescence imaging and non-invasive electrophysiology, we show that adult C. elegans generate bite forces during feeding on the order of 10?μN and that the temporal pattern of force generation is aligned with muscle activity in the feeding organ. Moreover, the bite force we measure corresponds to Hertzian contact stresses in the pressure range used to lyse the bacterial food of the worm. Microgauges have the potential to enable quantitative studies that investigate how neuromuscular stresses are affected by ageing, genetic mutations and drug treatments in this organ and other luminal organs.

機械工程Mechanical Engineering

Infrared nanosensors of piconewton to micronewton forces

皮牛頓力到微牛頓力的紅外納米傳感器

▲ 作者：Natalie Fardian-Melamed, Artiom Skripka, Benedikt Ursprung, Changhwan Lee, Thomas P. Darlington, Ayelet Teitelboim, et al.

▲鏈接：

https://www.nature.com/articles/s41586-024-08221-2

▲摘要：

機械力是許多物理和生物過程的基本特征，包括機器人、生物物理學、儲能和醫學在內的各種應用都需要高靈敏度和高空間分辨率的機械信號遠程測量。納米級發光力傳感器擅長測量皮牛頓力，而更大的傳感器在探測微牛頓力方面顯示出強大功能。然而，可從亞表面或界面位置遠程探測的力值仍然存在很大差距，且沒有一個單獨、非侵入式的傳感器能夠測量理解許多系統所需的大動態范圍。

研究組展示了Tm3+摻雜的雪崩納米粒子力傳感器，可通過深穿透近紅外光進行遠程定位，并且可以檢測動態范圍跨越四個數量級的皮牛頓到微牛頓的力。利用原子力顯微鏡結合單納米粒子光譜學，他們表征了光子雪崩過程的機械靈敏度，并揭示了其優異的力響應性。

通過控制納米傳感器內的Tm3+濃度和能量轉移，研究組展示了不同的光學力傳感模式，包括機械增亮和機械變色。這些納米級光學力傳感器的適應性以及多尺度傳感能力，使其能夠在現實世界的動態和多用途環境中運行，復雜的結構涵蓋了生物有機體到納米機電系統。

▲ Abstract：

Mechanical force is an essential feature for many physical and biological processes, and remote measurement of mechanical signals with high sensitivity and spatial resolution is needed for diverse applications, including robotics, biophysics, energy storage and medicine. Nanoscale luminescent force sensors excel at measuring piconewton forces, whereas larger sensors have proven powerful in probing micronewton forces. However, large gaps remain in the force magnitudes that can be probed remotely from subsurface or interfacial sites, and no individual, non-invasive sensor is capable of measuring over the large dynamic range needed to understand many systems. Here we demonstrate Tm3+-doped avalanching-nanoparticle force sensors that can be addressed remotely by deeply penetrating near-infrared light and can detect piconewton to micronewton forces with a dynamic range spanning more than four orders of magnitude. Using atomic force microscopy coupled with single-nanoparticle optical spectroscopy, we characterize the mechanical sensitivity of the photon-avalanching process and reveal its exceptional force responsiveness. By manipulating the Tm3+concentrations and energy transfer within the nanosensors, we demonstrate different optical force-sensing modalities, including mechanobrightening and mechanochromism. The adaptability of these nanoscale optical force sensors, along with their multiscale-sensing capability, enable operation in the dynamic and versatile environments present in real-world, complex structures spanning biological organisms to nanoelectromechanical systems.

地球科學Earth Science

Probabilistic weather forecasting with machine learning

機器學習助力概率天氣預報

▲ 作者：Ilan Price, Alvaro Sanchez-Gonzalez, Ferran Alet, Tom R. Andersson, Andrew El-Kadi, Dominic Masters, et al.

▲鏈接：

https://www.nature.com/articles/s41586-024-08252-9

▲摘要：

天氣預報基本上是不確定的，因此預測可能出現的天氣情況范圍（從警告公眾危險天氣到規劃可再生能源使用）對重要決策至關重要。傳統天氣預報基于數值天氣預報（NWP），它依賴于基于物理的大氣模擬。

基于機器學習（ML）的天氣預報（MLWP）的最新進展已產生了基于ML的模型，其預測誤差比單一NWP模擬更小。然而，這些進展主要集中在單一的、確定性的預測上，不能代表不確定性和估計風險。總體而言，MLWP仍然不如最先進的NWP集合預測準確可靠。

研究組介紹了GenCast（一種概率天氣模型），其能力和速度優于世界上最先進的中期天氣預報系統ENS（歐洲中期天氣預報中心的集合預報）。GenCast是一種經過數十年再分析數據訓練的ML天氣預報方法。

GenCast在8分鐘內生成了一個12小時步長、0.25°經緯度分辨率、超過80個地表和大氣變量的隨機15天全球預報集合。在研究組評估的1320個目標中，其中97.2%的目標GenCast的能力優于ENS，且能夠更好地預測極端天氣、熱帶氣旋路徑和風力發電。

該工作有助于打開業務天氣預報的新篇章，助力更準確、更有效地做出與天氣有關的關鍵決策。

▲ Abstract：

Weather forecasts are fundamentally uncertain, so predicting the range of probable weather scenarios is crucial for important decisions, from warning the public about hazardous weather to planning renewable energy use. Traditionally, weather forecasts have been based on numerical weather prediction (NWP), which relies on physics-based simulations of the atmosphere. Recent advances in machine learning (ML)-based weather prediction (MLWP) have produced ML-based models with less forecast error than single NWP simulations. However, these advances have focused primarily on single, deterministic forecasts that fail to represent uncertainty and estimate risk. Overall, MLWP has remained less accurate and reliable than state-of-the-art NWP ensemble forecasts. Here we introduce GenCast, a probabilistic weather model with greater skill and speed than the top operational medium-range weather forecast in the world, ENS, the ensemble forecast of the European Centre for Medium-Range Weather Forecasts. GenCast is an ML weather prediction method, trained on decades of reanalysis data. GenCast generates an ensemble of stochastic 15-day global forecasts, at 12-h steps and 0.25° latitude–longitude resolution, for more than 80 surface and atmospheric variables, in 8?min. It has greater skill than ENS on 97.2% of 1,320 targets we evaluated and better predicts extreme weather, tropical cyclone tracks and wind power production. This work helps open the next chapter in operational weather forecasting, in which crucial weather-dependent decisions are made more accurately and efficiently.

The progression of basaltic–rhyolitic melt storage at Yellowstone Caldera

黃石火山口玄武巖-流紋巖熔體儲層演化

▲ 作者：N. Bennington, A. Schultz, P. Bedrosian, E. Bowles-Martinez, K. Lynn, M. Stelten, et al.

▲鏈接：

https://www.nature.com/articles/s41586-024-08286-z

▲摘要：

黃石火山口是地球上最大的火山系統之一，在過去的200萬年間發生了三次重大火山口形成噴發，其間穿插著不那么劇烈、規模較小的噴發。黃石火山口形成噴發源于中上部地殼中儲存的流紋巖熔體。

地震層析成像研究表明，黃石火山口下方延伸著一個廣泛流紋巖熔體區域，估計熔體體積比過去最大的火山口形成噴發體積大一到四倍，預計熔體含量為6~28%。地震波速受溫度、壓力和熔體的強烈影響；然而，大地電磁數據主要對熔體的存在敏感，使這些數據成為約束火山系統的理想選擇。

研究組利用大地電磁數據來模擬黃石火山口地殼巖漿儲層的電阻率結構，并對該地區發生大型火山噴發的可能性進行約束。結果發現流紋巖熔體儲存在火山口下方熔體含量低的分離區域，表明儲層不容易噴發。通常，這些地區的熔體量相當于黃石火山爆發后的小體積噴發。

最大的流紋巖熔體儲存區域集中在黃石火山口東北部，其儲存量與黃石最小的火山口形成噴發規模相似。研究組確定了從下地殼遷移的玄武巖區域與東北流紋巖熔體儲存區融合并提供熱量。在此基礎上，研究組認為未來流紋巖火山活動的中心已經轉移到黃石火山口東北部。

▲ Abstract：

Yellowstone Caldera is one of the largest volcanic systems on Earth, hosting three major caldera-forming eruptions in the past two million years, interspersed with periods of less explosive, smaller-volume eruptions. Caldera-forming eruptions at Yellowstone are sourced by rhyolitic melts stored within the mid- to upper crust. Seismic tomography studies have suggested that a broad region of rhyolitic melt extends beneath Yellowstone Caldera, with an estimated melt volume that is one to four times greater than the eruptive volume of the largest past caldera-forming eruption, and an estimated melt fraction of 6–28?per cent. Seismic velocity is strongly influenced by temperature, pressure and melt; however, magnetotelluric data are primarily sensitive to the presence of melt, making these data ideal for constraining volcanic systems. Here we utilize magnetotelluric data to model the resistivity structure of Yellowstone Caldera’s crustal magma reservoir and constrain the region’s potential for producing major volcanic eruptions. We find that rhyolitic melts are stored in segregated regions beneath the caldera with low melt fractions, indicating that the reservoirs are not eruptible. Typically, these regions have melt volumes equivalent to small-volume post-caldera Yellowstone eruptions. The largest region of rhyolitic melt storage, concentrated beneath northeast Yellowstone Caldera, has a storage volume similar to the eruptive volume of Yellowstone’s smallest caldera-forming eruption. We identify regions of basalt migrating from the lower crust, merging with and supplying heat to the northeast region of rhyolitic melt storage. On the basis of our analysis, we suggest that the locus of future rhyolitic volcanism has shifted to northeast Yellowstone Caldera.