​《科学》（20201120出版）一周论文导读

Science, 20 NOVEMBER 2020, VOL 370, ISSUE 6519

《科学》2020年11月20日，第370卷，6519期

生态学Ecology

▲ 作者：Jeremy M. Cohen, Erin L. Sauer, Olivia Santiago, Samuel Spencer, et al.

▲ 链接：

https://science.sciencemag.org/content/370/6519/eabb1702

▲ 摘要

近几十年来，随着气候变化，野生动物之间的疾病爆发激增，但气候变化如何改变不同地理区域的疾病动态仍不清楚。

我们收集了一个全球时空数据集，描述了7346个野生动物种群和2021个寄主组合的寄生虫流行情况，并编写了每个地点的当地天气和气候记录。

我们发现，来自寒冷气候和温暖气候的寄主，在异常的温暖和寒冷温度下，分别经历了增加的疾病风险，正如热错配假说所预测的那样。这种效应在外温寄主中最为显著，在陆地和淡水系统中也类似。

基于气候变化模型的预测表明，来自温带和热带的外温野生动物宿主可能分别经历疾病风险的急剧增加和适度减少，这些变化的大小取决于寄生虫的身份。

▲ Abstract

Disease outbreaks among wildlife have surged in recent decades alongside climate change, although it remains unclear how climate change alters disease dynamics across different geographic regions. We amassed a global, spatiotemporal dataset describing parasite prevalence across 7346 wildlife populations and 2021 host-parasite combinations, compiling local weather and climate records at each location. We found that hosts from cool and warm climates experienced increased disease risk at abnormally warm and cool temperatures, respectively, as predicted by the thermal mismatch hypothesis. This effect was greatest in ectothermic hosts and similar in terrestrial and freshwater systems. Projections based on climate change models indicate that ectothermic wildlife hosts from temperate and tropical zones may experience sharp increases and moderate reductions in disease risk, respectively, though the magnitude of these changes depends on parasite identity.

物理学Physics

▲ 作者：Donato Civita, Marek Kolmer, Grant J. Simpson, An-Ping Li, Stefan Hecht, et al.

▲ 链接：

https://science.sciencemag.org/content/370/6519/957

▲ 摘要

分子运动的空间控制通常是有限的，因为在原子尺度上的运动遵循随机过程。我们使用扫描隧道显微镜将单个分子带入一个稳定的高平移移动方向，他们沿着精确定义的轨道移动。

单个二溴芴分子在银(111)表面以0.1埃的极高空间精度移动了150纳米的距离。静电效应的性质使得有选择性地应用排斥力和引力来发送或接收单个分子。

高控制允许我们精确地移动单个和特定的分子实体之间的两个单独的探针，为速度测量，从而在扩散和碰撞过程中实时研究单个分子的能量耗散开辟了道路。

▲ Abstract

Spatial control over molecular movement is typically limited because motion at the atomic scale follows stochastic processes. We used scanning tunneling microscopy to bring single molecules into a stable orientation of high translational mobility where they moved along precisely defined tracks. Single dibromoterfluorene molecules moved over large distances of 150 nanometers with extremely high spatial precision of 0.1 angstrom across a silver (111) surface. The electrostatic nature of the effect enabled the selective application of repulsive and attractive forces to send or receive single molecules. The high control allows us to precisely move an individual and specific molecular entity between two separate probes, opening avenues for velocity measurements and thus energy dissipation studies of single molecules in real time during diffusion and collision.

▲ 作者：Kyung Hwan Kim, Katrin Amann-Winkel, Nicolas Giovambattista, Alexander Späh, Fivos Perakis, et al.

▲ 链接：

https://science.sciencemag.org/content/370/6519/978

▲ 摘要

通过利用红外飞秒激光，将高密度非晶冰等容加热至205±10 k，我们在压力环境下制备了大量超冷水样品。由于样品密度在超快加热期间保持不变，我们可以估计高密度液相的初始内压为2.5 - 3.5千巴。

加热后，样品迅速膨胀，我们用飞秒x射线激光在不同的泵浦探针延迟时间下捕获了减压过程。在20纳秒到3微秒的时间尺度内出现并生长低密度液体畴，而结晶在3到50微秒的时间尺度内发生不连续的结构变化。

这两个过程的动力学被超过一个数量级的分离提供了支持液-液转变的超冷水。

▲ Abstract

We prepared bulk samples of supercooled liquid water under pressure by isochoric heating of high-density amorphous ice to temperatures of 205 ± 10 kelvin, using an infrared femtosecond laser. Because the sample density is preserved during the ultrafast heating, we could estimate an initial internal pressure of 2.5 to 3.5 kilobar in the high-density liquid phase. After heating, the sample expanded rapidly, and we captured the resulting decompression process with femtosecond x-ray laser pulses at different pump-probe delay times. A discontinuous structural change occurred in which low-density liquid domains appeared and grew on time scales between 20 nanoseconds to 3 microseconds, whereas crystallization occurs on time scales of 3 to 50 microseconds. The dynamics of the two processes being separated by more than one order of magnitude provides support for a liquid-liquid transition in bulk supercooled water.

材料科学Materials Science

▲ 作者：Sunghoon Lee, Sae Franklin, Faezeh Arab Hassani, Tomoyuki Yokota, et al.

▲ 链接：

https://science.sciencemag.org/content/370/6519/966

▲ 摘要

监控手指操作而不干扰固有功能是理解自然触觉的关键。然而，佩戴或附着的传感器会影响皮肤的自然感觉。

我们开发了纳米压力传感器，它可以监测手指的压力，而不会对人体感觉产生可察觉的影响。

我们定量调查了传感器对人体触觉的影响，佩戴传感器的手指表现出了和不佩戴传感器的手指一样的抓握力量，虽然薄膜附着物因摩擦调整后增加了14%的抓握力量。

同时，传感器展示了一个极端的机械耐久性抗循环剪切和摩擦大于数百千帕。

▲ Abstract

Monitoring of finger manipulation without disturbing the inherent functionalities is critical to understand the sense of natural touch. However, worn or attached sensors affect the natural feeling of the skin. We developed nanomesh pressure sensors that can monitor finger pressure without detectable effects on human sensation. The effect of the sensor on human sensation was quantitatively investigated, and the sensor-applied finger exhibits comparable grip forces with those of the bare finger, even though the attachment of a 2-micrometer-thick polymeric film results in a 14% increase in the grip force after adjusting for friction. Simultaneously, the sensor exhibits an extreme mechanical durability against cyclic shearing and friction greater than hundreds of kilopascals.

天文学Astronomy

▲ 作者：Søren S. Larsen, Aaron J. Romanowsky, Jean P. Brodie, Asher Wasserman

▲ 链接：

https://science.sciencemag.org/content/370/6519/970

▲ 摘要

球状星团（GCs）是由成千上万到数百万颗恒星组成的致密、受引力束缚的系统。它们更易与星系中最古老的成分联系在一起，因此对它们成分的测量可以限制星系在早期宇宙中化学元素的积累。

我们报告，在仙女座星系（M31）中有一个极度缺乏重元素的巨大球状星团，RBC EXT8。它的铁含量大约是太阳的1/800，大约是已知的最缺铁地球碳的1/ 3。它的镁含量也极度缺乏。

这些测量结果对球状星团的金属丰度底板的概念和理论预期提出了挑战，即巨大的球状星团不可能在如此低的金属丰度下形成。

▲ Abstract

Globular clusters (GCs) are dense, gravitationally bound systems of thousands to millions of stars. They are preferentially associated with the oldest components of galaxies, so measurements of their composition can constrain the build-up of chemical elements in galaxies during the early Universe. We report a massive GC in the Andromeda Galaxy (M31), RBC EXT8, that is extremely depleted in heavy elements. Its iron abundance is about 1/800 that of the Sun and about one-third that of the most iron-poor GCs previously known. It is also strongly depleted in magnesium. These measurements challenge the notion of a metallicity floor for GCs and theoretical expectations that massive GCs could not have formed at such low metallicities.

地理学Geography

▲ 作者：Songqiao Shawn Wei, Peter M. Shearer, Carolina Lithgow-Bertelloni, Lars Stixrude, Dongdong Tian

▲ 链接：

https://science.sciencemag.org/content/370/6519/983

▲ 摘要

包括夏威夷火山在内的夏威夷-皇帝海山链是由夏威夷地幔柱运动形成的。尽管地幔柱假说预测了一个海洋高原，它是在夏威夷热点形成的初始阶段由大规模的减压融化所产生的，但这个高原的命运仍不清楚。

通过叠加SS前兆的地震波形，我们在鄂霍次克海以西的上、下地幔中发现了一个百万级的加厚海洋地壳。我们认为，这一厚地壳代表了海洋高原的一个主要部分，它是在1亿年前由夏威夷地幔柱形成的，并在2000万至3000万年前被俯冲下来。

我们的发现为夏威夷地幔柱的早期历史提供了时间和空间线索，为未来的板块重建提供了依据。

▲ Abstract

The Hawaiian-Emperor seamount chain that includes the Hawaiian volcanoes was created by the Hawaiian mantle plume. Although the mantle plume hypothesis predicts an oceanic plateau produced by massive decompression melting during the initiation stage of the Hawaiian hot spot, the fate of this plateau is unclear. We discovered a megameter-scale portion of thickened oceanic crust in the uppermost lower mantle west of the Sea of Okhotsk by stacking seismic waveforms of SS precursors. We propose that this thick crust represents a major part of the oceanic plateau that was created by the Hawaiian plume head ~100 million years ago and subducted 20 million to 30 million years ago. Our discovery provides temporal and spatial clues of the early history of the Hawaiian plume for future plate reconstructions.