海马研究论文

编译 | 李言

Nature , 7 April 2022, Volume 604 Issue 7904

《自然》 2022年4月7日，第604卷，7904期

天文学 Astronomy

UV absorption by silicate cloud precursors in ultra-hot Jupiter WASP-178b

木星大小的高温行星WASP-178b中硅酸盐云前驱体对紫外线的吸收

作者：Joshua D. Lothringer, David K. Sing, Zafar Rustamkulov, Hannah R. Wakeford, Kevin B. Stevenson, Nikolay Nikolov, Panayotis Lavvas, Jessica J. Spake & Autumn T. Winch

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摘要：

在此，我们报道了木星大小的高温行星WASP-178b（约2450 K）的近紫外透射光谱，它显示了大量的吸收。贝叶斯反演表明存在含硅和镁的气态耐火物质，它们是低温下凝结云的前兆。

据先前研究，一氧化硅此前未曾在系外行星中探测到，但WASP-178b中一氧化硅的含量与理论预期一致，即高温下的主要硅元素来源。这些使我们能重新解释HAT-P-41b和WASP-121b此前没有考虑一氧化硅的观测结果，表明硅酸盐云的形成开始于1950到2450 K之间的平衡温度的系外行星。

Abstract：

Here we report the near-ultraviolet transmission spectrum of the ultra-hot Jupiter WASP-178b (approximately 2,450 K), which exhibits substantial absorption. Bayesian retrievals indicate the presence of gaseous refractory species containing silicon and magnesium, which are the precursors to condensate clouds at lower temperatures. SiO, in particular, has not previously, to our knowledge, been detected in exoplanets, but the presence of SiO in WASP-178b is consistent with theoretical expectations as the dominant Si-bearing species at high temperatures. These observations allow us to re-interpret previous observations of HAT-P-41b and WASP-121b that did not consider SiO, to suggest that silicate cloud formation begins on exoplanets with equilibrium temperatures between 1,950 and 2,450 K.

物理学 Physics

Search for Majorana neutrinos exploiting millikelvin cryogenics with CUORE

利用极低温环境晶体寻找马约拉纳中微子

作者：The CUORE Collaboration

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摘要

在此，我们展示了最新的低温器和CUORE实验对130Te晶体中无中微子双贝塔衰变的搜索结果。CUORE实验的运行温度仅比绝对零度高10毫微，它在三个方面提高了将技术前沿：超低温度下的质量、运行寿命和低温基础设施产生的低水平电离辐射。

结果表明，无中微子双贝塔在90%的可信区间内没有出现衰变现象，且其半衰期下限为 1025年。我们讨论了CUORE在其他领域的潜在应用进展，如直接暗物质、中微子和核物理搜索以及大规模量子计算，这得益于在低放射性、超低温低温环境中持续运行的大规模有效载荷。

Abstract

Here we show results from the search for 0νββ decay of130Te, using the latest advanced cryogenic calorimeters with the CUORE experiment. CUORE, operating just 10 millikelvin above absolute zero, has pushed the state of the art on three frontiers: the sheer mass held at such ultralow temperatures, operational longevity, and the low levels of ionizing radiation emanating from the cryogenic infrastructure. We find no evidence for 0νββ decay and set a lower bound of the process half-life as 1025years at a 90 per cent credibility interval. We discuss potential applications of the advances made with CUORE to other fields such as direct dark matter, neutrino and nuclear physics searches and large-scale quantum computing, which can benefit from sustained operation of large payloads in a low-radioactivity, ultralow-temperature cryogenic environment.

材料科学 Material Science

Charge-density-wave-driven electronic nematicity in a kagome superconductor

笼目超导体中发现新型电子向列相

作者：Linpeng Nie, Kuanglv Sun, Wanru Ma, Dianwu Song, Lixuan Zheng et al.

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摘要

我们通过弹性电阻、核磁共振（NMR）和扫描隧道显微镜/光谱（STM/S）三种技术的结合，发现了笼目超导体CsV3Sb5中存在电子向列相的证据。随温度变化的弹性电阻系数（m11 - m12和核磁共振谱表明，2a0   2a0超级单体由于面外调制而产生 C2 结构畸变，在电荷密度波跃迁（约94开尔文）下方会出现相当大的向列波动，最后在35开尔文以下会出现向列跃迁。

STM实验实现了 C2 -结构固定的长程向列向转变温度以下的向列相，提出了一种由three state Potts模型描述的新型向列相。

Abstract

Here we report evidence for the existence of electronic nematicity in CsV3Sb5, using a combination of elastoresistance measurements, nuclear magnetic resonance (NMR) and scanning tunnelling microscopy/spectroscopy (STM/S). The temperature-dependent elastoresistance coefficient (m11 minus m12) and NMR spectra demonstrate that, besides a C2 structural distortion of the 2a0   2a0 supercell owing to out-of-plane modulation, considerable nematic fluctuations emerge immediately below the CDW transition (approximately 94 kelvin) and finally a nematic transition occurs below about 35 kelvin. The STM experiment directly visualizes the C2 -structure-pinned long-range nematic order below the nematic transition temperature, suggesting a novel nematicity described by a three-state Potts model.

Ultrathin ferroic HfO2–ZrO2 superlattice gate stack for advanced transistors

可用于先进晶体管的超薄铁质HfO2–ZrO2 超晶格栅叠层

作者：Suraj S. Cheema, Nirmaan Shanker, Li-Chen Wang, Cheng-Hsiang Hsu et al.

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摘要

在此，我们报告HfO2–ZrO2超晶格异质结构作为栅叠层，通过混合铁电性-反铁电性顺序稳定，直接集成到Si晶体管上，并缩小到大约20埃，与高性能晶体管所需的栅极氧化厚度相同。金属氧化物半导体电容器的整体等效氧化层厚度相当于埃的二氧化硅有效厚度。

在传统的HfO2基高介电常数栅极堆中，如果不清除表面的二氧化硅，就无法获得如此低的有效氧化层厚度和由此产生的大电容，这对电子传输和栅极漏电流有不利影响。因此，我们的栅极堆栈不需要这样清除即可提供更低的泄漏电流和无迁移率退化。

Abstract

Here we report HfO2–ZrO2 superlattice heterostructures as a gate stack, stabilized with mixed ferroelectric–antiferroelectric order, directly integrated onto Si transistors, and scaled down to approximately 20 ångströms , the same gate oxide thickness required for high-performance transistors. The overall equivalent oxide thickness in metal–oxide–semiconductor capacitors is equivalent to an effective SiO2 thickness of approximately . Such a low effective oxide thickness and the resulting large capacitance cannot be achieved in conventional HfO2-based high-dielectric-constant gate stacks without scavenging the interfacial SiO2, which has adverse effects on the electron transport and gate leakage current. Accordingly, our gate stacks, which do not require such scavenging, provide substantially lower leakage current and no mobility degradation.

生物学 Biology

A stable hippocampal code in freely flying bats

自由飞行蝙蝠体内稳定的海马编码

作者：William A. Liberti III, Tobias A. Schmid, Angelo Forli, Madeleine Snyder & Michael M. Yartsev

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摘要

在此，我们使用无线钙成像技术来纵向监测自由飞行的蝙蝠背部CA1海马神经元的活动，它们在熟悉的环境中进行高度可重复性的飞行。我们发现大多数神经元的参与和空间选择性在数天和数周内保持稳定。我们还发现，调谐的明显变化在很大程度上可以归因于蝙蝠飞行行为的变化。

最后，我们发现，在相同的环境中，蝙蝠在不同的房间照明条件下（开灯和关灯）飞行时，飞行行为发生了巨大的变化，这可能会给人一种神经元不稳定的错觉。

然而，在不同条件下比较相似的飞行路径时，海马编码的稳定性持续存在。综上所述，我们发现如果把行为考虑在内，潜在的海马编码在几天内和跨环境中都是高度稳定的。

Abstract

Here we used wireless calcium imaging to longitudinally monitor the activity of dorsal CA1 hippocampal neurons in freely flying bats performing highly reproducible flights in a familiar environment. We find that both the participation and the spatial selectivity of most neurons remain stable over days and weeks. We also find that apparent changes in tuning can be largely attributed to variations in the flight behaviour of the bats. Finally, we show that bats navigating in the same environment under different room lighting conditions (lights on versus lights off) exhibit substantial changes in flight behaviour that can give the illusion of neuronal instability. However, when similar flight paths are compared across conditions, the stability of the hippocampal code persists. Taken together, we show that the underlying hippocampal code is highly stable over days and across contexts if behaviour is taken into account.

神经科学 Neurosciences

Entropy of city street networks linked to future spatial navigation ability

与未来空间导航能力相关的城市街道网络熵

作者：A. Coutrot, E. Manley, S. Goodroe, C. Gahnstrom, G. Filomena, D. Yesiltepe, R. C. Dalton, J. M. Wiener, C. Hlscher, M. Hornberger & H. J. Spiers

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摘要

在此，我们使用一个嵌入在电子 游戏 中的认知任务来测量来自世界38个国家的397162人的非语言空间导航能力。总的来说，我们发现在非城市地区长大的人更擅长导航。更具体地说，人们更善于在与他们成长的地方拓扑相似的环境中导航。

生长在较低的城市街道网络熵（如芝加哥）的人在布局规则的电子 游戏 中有较好表现，而成长在城市以外地区或更高的街道网络熵（如布拉格）的人在熵值较高的视频 游戏 上表现更好。

这为环境在全球范围内对人类认知的影响提供了证据，并强调了城市设计在人类认知和大脑功能中的重要性。

Abstract

Here we used a cognitive task embedded in a video game to measure non-verbal spatial navigation ability in 397,162 people from 38 countries across the world. Overall, we found that people who grew up outside cities were better at navigation. More specifically, people were better at navigating in environments that were topologically similar to where they grew up. Growing up in cities with a low street network entropy (for example, Chicago) led to better results at video game levels with a regular layout, whereas growing up outside cities or in cities with a higher street network entropy (for example, Prague) led to better results at more entropic video game levels. This provides evidence of the effect of the environment on human cognition on a global scale, and highlights the importance of urban design in human cognition and brain function