自然科学基础电子书：自然20221013出版一周论文导读

自然科学基础电子书：自然20221013出版一周论文导读https://www.nature.com/articles/s41586-022-05147-5▲ 链接：Layered subsurface in Utopia Basin of Mars revealed by Zhurong rover radar祝融号巡视雷达揭示火星乌托邦平原浅表结构▲ 作者：Chao Li Yikang Zheng Xin Wang Jinhai Zhang et al.

编译 | 李言

Nature 13 October 2022 Volume 610 Issue 7931

《自然》2022年10月13日，第610卷，7931期

天文学Astronomy

Layered subsurface in Utopia Basin of Mars revealed by Zhurong rover radar

祝融号巡视雷达揭示火星乌托邦平原浅表结构

▲ 作者：Chao Li Yikang Zheng Xin Wang Jinhai Zhang et al.

▲ 链接：

https://www.nature.com/articles/s41586-022-05147-5

▲ 摘要：

在此，我们报告由“天问一号”携带的祝融号火星车在乌托邦平原南部边缘地区进行的火星地下结构的现场探地雷达调查。沿着火星车约1171米的行进路线，我们构建了详细的地下图像，显示了在不到10米厚的风化层下约70米厚的多层结构分层。尽管其他模型值得进一步研究，但新的雷达图像显示了偶发水活动的发生，这可能代表了在晚西方纪到亚马逊纪期间乌托邦平原曾发生盆地充填。虽然在雷达探测深度范围内没有发现液态水存在的直接证据，但我们不能排除在着陆区的地下可能存在盐冰。

▲ Abstract：

Here we report an in situ ground-penetrating radar survey of Martian subsurface structure in a southern marginal area of Utopia Planitia conducted by the Zhurong rover of the Tianwen-1 mission. A detailed subsurface image profile is constructed along the roughly 1 171 m traverse of the rover showing an approximately 70-m-thick multi-layered structure below a less than 10-m-thick regolith. Although alternative models deserve further scrutiny the new radar image suggests the occurrence of episodic hydraulic flooding sedimentation that is interpreted to represent the basin infilling of Utopia Planitia during the Late Hesperian to Amazonian. While no direct evidence for the existence of liquid water was found within the radar detection depth range we cannot rule out the presence of saline ice in the subsurface of the landing area.

Radiation-driven acceleration in the expanding WR140 dust shell

膨胀的WR140尘埃壳层中的辐射驱动加速

▲ 作者：Yinuo Han Peter G. Tuthill Ryan M. Lau & Anthony Soulain

▲ 链接：

https://www.nature.com/articles/s41586-022-05155-5

▲ 摘要：

Wolf-Rayet （WR）双星系统WR140是一颗近距离双星，由一颗O5主星和一颗WC7伴星组成。在此，我们展示了WR140星尘埃壳层的图像。我们构建了几何模型，密切追踪结构复杂的尘埃羽流的膨胀，表明轨道调制引起的复杂效应可能会导致尘埃产生的“适居带”。我们发现，在简单的等速外流的假设下，无法再现尘埃羽流的膨胀，而是灰尘在加速。这构成了辐射压力加速下尘埃运动的运动学直接记录，并进一步突出了恒星风碰撞产生的物理条件复杂性。

▲ Abstract：

The Wolf–Rayet (WR) binary system WR140 is a close binary star consisting of an O5 primary and WC7 companion and is known as the archetype of episodic dust-producing WRs. Here we present multiepoch imagery of the circumstellar dust shell of WR140. We constructed geometric models that closely trace the expansion of the intricately structured dust plume showing that complex effects induced by orbital modulation may result in a ‘Goldilocks zone’ for dust production. We find that the expansion of the dust plume cannot be reproduced under the assumption of a simple uniform-speed outflow finding instead the dust to be accelerating. This constitutes a direct kinematic record of dust motion under acceleration by radiation pressure and further highlights the complexity of the physical conditions in colliding-wind binaries.

化学Chemistry

Optical superluminal motion measurement in the neutron-star merger GW170817

GW170817中子星并合中的光学超光速运动测量

▲ 作者：Kunal P. Mooley Jay Anderson & Wenbin Lu

▲ 链接：

https://www.nature.com/articles/s41586-022-05145-7

▲ 摘要：

双星中子星并合GW170817的余辉为结构化相对论喷流以及这种并合与短伽马暴之间的联系提供了证据。在此，我们报道了另一个七倍光速的超光速运动测量，利用哈勃空间望远镜的精密天体测量和之前的无线电VLBI数据检测GW170817。我们因而得到了结构射流机翼的洛伦兹因子的测量值，以及对观测角（19-25度）和射流核心的初始洛伦兹因子（大于40）的大幅提升。

▲ Abstract：

The afterglow of the binary neutron-star merger GW170817 gave evidence for a structured relativistic jet and a link between such mergers and short gamma-ray bursts. Here we report on another superluminal motion measurement at seven times the speed of light leveraging Hubble Space Telescope precision astrometry and previous radio VLBI data for GW170817. We thereby obtain a measurement of the Lorentz factor of the wing of the structured jet as well as substantially improved constraints on the viewing angle (19–25 degrees) and the initial Lorentz factor of the jet core (more than 40).

工程学Engineering Science

Personalizing exoskeleton assistance while walking in the real world

在现实世界中行走时可使用的个性化外骨骼辅助

▲ 作者：Patrick Slade Mykel J. Kochenderfer Scott L. Delp & Steven H. Collins

▲ 链接：

https://www.nature.com/articles/s41586-022-05191-1

▲ 摘要：

个性化的外骨骼辅助为用户提供了行走速度和能源节约方面的最大改善，但需要在非自然实验室条件下进行冗长的测试。在此，我们展示了外骨骼优化可以在现实条件下快速实现。基于多次实验室测试，我们设计了一种便携式踝关节外骨骼。利用可穿戴传感器优化外骨骼户外辅助，我们开发了一种数据驱动的方法，并发现它与实验室方法同样有效，但确定最佳参数的速度是实验室方法的四倍。我们使用以不同速度行走时收集的数据进行了现实世界的优化。相比普通辅助鞋，该辅助在公共场合自然行走一个小时后会进行自动优化，速度提升9±4%，同时减少17±5%给定距离范围消耗的能源。当参与者以1.5 m s−1的标准速度在跑步机上行走时，这种辅助降低了23±8%的代谢能量消耗。人体动作编码的信息可用于个性化辅助设备和提高性能。

▲ Abstract：

Personalized exoskeleton assistance provides users with the largest improvements in walking speed1 and energy economy but requires lengthy tests under unnatural laboratory conditions. Here we show that exoskeleton optimization can be performed rapidly and under real-world conditions. We designed a portable ankle exoskeleton based on insights from tests with a versatile laboratory testbed. We developed a data-driven method for optimizing exoskeleton assistance outdoors using wearable sensors and found that it was equally effective as laboratory methods but identified optimal parameters four times faster. We performed real-world optimization using data collected during many short bouts of walking at varying speeds. Assistance optimized during one hour of naturalistic walking in a public setting increased self-selected speed by 9 ± 4% and reduced the energy used to travel a given distance by 17 ± 5% compared with normal shoes. This assistance reduced metabolic energy consumption by 23 ± 8% when participants walked on a treadmill at a standard speed of 1.5 m s−1. Human movements encode information that can be used to personalize assistive devices and enhance performance.

Multi-environment robotic transitions through adaptive morphogenesis

通过适应性形态发生实现多环境机器人转化

▲ 作者：Robert Baines Sree Kalyan Patiballa Joran Booth Luis Ramirez Thomas Sipple Andonny Garcia Frank Fish & Rebecca Kramer-Bottiglio

▲ 链接：

https://www.nature.com/articles/s41586-022-05188-w

▲ 摘要：

在此，为了在陆地、水中和过渡区域实现专业化的多环境运动，我们运用了“适应性形态发生”——一种通过统一的结构和驱动系统实现自适应机器人形态和行为的设计策略。我们从陆生和水生海龟身上获得灵感制作了一个机器人。通过融合传统的刚性组件和软材料，从根本上增强了它的四肢形状，并改变了它的步态，以适应多种环境的运动。步态、肢体形状和与环境的相互作用是了解控制机器人运输成本的重要参数。结果表明，适应性形态发生是提高移动机器人面对非结构化、变化环境的效率的有效方法。

▲ Abstract：

Here to achieve specialized multi-environment locomotion through terrestrial aquatic and the in-between transition zones we implemented ‘adaptive morphogenesis’ a design strategy in which adaptive robot morphology and behaviours are realized through unified structural and actuation systems. Taking inspiration from terrestrial and aquatic turtles we built a robot that fuses traditional rigid components and soft materials to radically augment the shape of its limbs and shift its gaits for multi-environment locomotion. The interplay of gait limb shape and the environmental medium revealed vital parameters that govern the robot’s cost of transport. The results attest that adaptive morphogenesis is a powerful method to enhance the efficiency of mobile robots encountering unstructured changing environments.

古生物Paleontology

Scleromochlus and the early evolution of Pterosauromorpha

斯克列罗龙与翼龙的早期进化

▲ 作者：Davide Foffa Emma M. Dunne Sterling J. Nesbitt et al.

▲ 链接：

https://www.nature.com/articles/s41586-022-05284-x

▲ 摘要：

一个多世纪前发现的苏格兰晚三叠世早期的小型爬行动物斯克列罗龙（Scleromochlus taylori）被认为是与翼龙密切相关的姊妹分类单元。但因其化石的不佳的留存情况限制了之前的研究，导致了对系统发育位置的争议，一些人甚至怀疑它是一种祖龙。在此，我们使用显微计算机断层扫描提供了第一个斯克列罗龙的精确全骨骼重建和修正诊断，揭示了新的解剖细节，最终确定它是翼龙属中的翼龙近亲。斯克列罗龙在解剖学上更类似于长柄龙而不是翼龙，并保留了许多可能存在于早期鸟跖类分支成员的特征。这些结果支持了这样一种假设：第一批会飞的爬行动物是从微小的，可能是适于行走的双足祖先进化而来的。

▲ Abstract：

Scleromochlus taylori a tiny reptile from the early Late Triassic of Scotland discovered over a century ago was hypothesized to be a key taxon closely related to pterosaurs but its poor preservation has limited previous studies and resulted in controversy over its phylogenetic position with some even doubting its identification as an archosaur. Here we use microcomputed tomographic scans to provide the first accurate whole-skeletal reconstruction and a revised diagnosis of Scleromochlus revealing new anatomical details that conclusively identify it as a close pterosaur relative within Pterosauromorpha (the lagerpetid pterosaur clade). Scleromochlus is anatomically more similar to lagerpetids than to pterosaurs and retains numerous features that were probably present in very early diverging members of Avemetatarsalia (bird-line archosaurs). These results support the hypothesis that the first flying reptiles evolved from tiny probably facultatively bipedal cursorial ancestors.