《自然》（20250102出版）一周论文导读

天文学Astronomy

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

▲ 链接：

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

▲ 摘要：

快速射电暴（FRBs）是一种持续时间在微秒到毫秒之间的射电瞬变现象，主要来自河外距离。FRB的发射机制仍有争议，主要有两种相互竞争的模型：发生在靠近中央引擎的物理过程；以及传播到大径向距离的相对论性激波。这两种模型的预期发射区域大小有显著差异。

研究组提出了FRB 20221022A频谱中两个相互相干闪烁尺度的测量：一个源自位于银河系内的散射屏，第二个源自其宿主星系或局部环境。使用散射介质作为天体物理透镜，可将观测到的FRB横向发射区域的规模限制在≤3×10⁴千米。

这种发射尺寸与大径向距离模型的预期不一致，更自然的解释是在中心致密天体的磁层内或磁层外发生了发射过程。最近，人们发现FRB 20221022A呈现S形偏振角摆动，极有可能源自磁层发射过程。

这项工作中提出的闪烁结果独立支持这一结论，同时强调闪烁是人们理解FRB发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 ≲3×10⁴ kilometres. 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.

材料科学Materials Science

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

▲ 链接：

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

▲ 摘要：

硅光子学是一项快速发展的技术，有望彻底改变人们沟通、计算和感知世界的方式。然而，缺乏高可扩展性的原生互补金属氧化物半导体（CMOS）集成光源是阻碍其广泛采用的主要因素之一。尽管III-V族光源在硅上的混合和异质集成取得了相当大的进展，但III-V族材料的直接外延单片集成仍是具有最佳成本效益的片上光源。

研究组报道了基于纳米脊工程的新集成方法，在CMOS试产线上，在300 mm硅晶圆上完全制造了电驱动砷化镓（GaAs）基激光二极管。嵌入p-i-n二极管和InGaAs量子阱的GaAs纳米脊波导在晶圆尺度上高质量生长。在晶圆上的300多个器件中，室温连续波激光的波长约为1020 nm，阈值电流低至5 mA，输出功率超过1 mW，激光线宽低至46 MHz，激光工作温度高达55℃。

这些结果表明了III-V/Si纳米脊工程概念在硅光子学平台中单片集成激光二极管的潜力，有望实现光学传感、互连等领域的成本敏感型大批量应用。

▲ 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.

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

▲ 链接：

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

▲ 摘要：

肌肉细胞中动作电位产生的力将血液、食物和废物运送到全身的管腔结构。虽然存在无创电生理技术，但大多数机械传感器无法无创进入管腔结构。

研究组介绍了无毒的可摄入式机械传感器，以实现管腔力的定量研究，并将其应用于研究活体秀丽隐杆线虫的摄食。这些光学“微测量仪”由嵌入上转换NaY_0.8Yb_0.18Er_0.02F₄@NaYF₄纳米颗粒的聚苯乙烯微球组成。结合光学显微镜和原子力显微镜在体外研究的微测量仪，他们发现力引起发射红光和绿光比率的线性和无迟滞变化。

通过荧光成像和无创电生理学分析，研究组发现成年秀丽隐杆线虫在进食过程中产生10 μ N左右的咬合力，并且咬合力产生的时间模式与进食器官的肌肉活动一致。此外，研究组测量的咬合力与用于分解虫体细菌食物的压力范围内的赫兹接触应力一致。

微测量仪有望进行定量研究，以探索该器官和其他管腔器官中神经肌肉压力如何受到衰老、基因突变和药物治疗的影响。

▲ 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 NaY_0.8Yb_0.18Er_0.02F₄@NaYF₄ nanoparticles 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.

机械工程Mechanical Engineering

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

▲ 链接：

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

▲ 摘要：

机械力是许多物理和生物过程的基本特征，包括机器人、生物物理学、储能和医学在内的各种应用都需要高灵敏度和高空间分辨率的机械信号远程测量。纳米级发光力传感器擅长测量皮牛顿力，而更大的传感器在探测微牛顿力方面显示出强大功能。然而，可从亚表面或界面位置远程探测的力值仍然存在很大差距，且没有一个单独、非侵入式的传感器能够测量理解许多系统所需的大动态范围。

研究组展示了Tm³⁺掺杂的雪崩纳米粒子力传感器，可通过深穿透近红外光进行远程定位，并且可以检测动态范围跨越四个数量级的皮牛顿到微牛顿的力。利用原子力显微镜结合单纳米粒子光谱学，他们表征了光子雪崩过程的机械灵敏度，并揭示了其优异的力响应性。

通过控制纳米传感器内的Tm³⁺浓度和能量转移，研究组展示了不同的光学力传感模式，包括机械增亮和机械变色。这些纳米级光学力传感器的适应性以及多尺度传感能力，使其能够在现实世界的动态和多用途环境中运行，复杂的结构涵盖了生物有机体到纳米机电系统。

▲ 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.

地球科学Earth Science

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

▲ 链接：

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

▲ 摘要：

天气预报基本上是不确定的，因此预测可能出现的天气情况范围（从警告公众危险天气到规划可再生能源使用）对重要决策至关重要。传统天气预报基于数值天气预报（NWP），它依赖于基于物理的大气模拟。

基于机器学习（ML）的天气预报（MLWP）的最新进展已产生了基于ML的模型，其预测误差比单一NWP模拟更小。然而，这些进展主要集中在单一的、确定性的预测上，不能代表不确定性和估计风险。总体而言，MLWP仍然不如最先进的NWP集合预测准确可靠。

研究组介绍了GenCast（一种概率天气模型），其能力和速度优于世界上最先进的中期天气预报系统ENS（欧洲中期天气预报中心的集合预报）。GenCast是一种经过数十年再分析数据训练的ML天气预报方法。

GenCast在8分钟内生成了一个12小时步长、0.25°经纬度分辨率、超过80个地表和大气变量的随机15天全球预报集合。在研究组评估的1320个目标中，其中97.2%的目标GenCast的能力优于ENS，且能够更好地预测极端天气、热带气旋路径和风力发电。

该工作有助于打开业务天气预报的新篇章，助力更准确、更有效地做出与天气有关的关键决策。

▲ 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.

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

▲ 链接：

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

▲ 摘要：

黄石火山口是地球上最大的火山系统之一，在过去的200万年间发生了三次重大火山口形成喷发，其间穿插着不那么剧烈、规模较小的喷发。黄石火山口形成喷发源于中上部地壳中储存的流纹岩熔体。

地震层析成像研究表明，黄石火山口下方延伸着一个广泛流纹岩熔体区域，估计熔体体积比过去最大的火山口形成喷发体积大一到四倍，预计熔体含量为6~28%。地震波速受温度、压力和熔体的强烈影响；然而，大地电磁数据主要对熔体的存在敏感，使这些数据成为约束火山系统的理想选择。

研究组利用大地电磁数据来模拟黄石火山口地壳岩浆储层的电阻率结构，并对该地区发生大型火山喷发的可能性进行约束。结果发现流纹岩熔体储存在火山口下方熔体含量低的分离区域，表明储层不容易喷发。通常，这些地区的熔体量相当于黄石火山爆发后的小体积喷发。

最大的流纹岩熔体储存区域集中在黄石火山口东北部，其储存量与黄石最小的火山口形成喷发规模相似。研究组确定了从下地壳迁移的玄武岩区域与东北流纹岩熔体储存区融合并提供热量。在此基础上，研究组认为未来流纹岩火山活动的中心已经转移到黄石火山口东北部。

▲ 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.