编译 | 冯维维

Nature, Volume 627 Issue 8002, 7 March 2024

《自然》第627卷，8002期，2024年3月7日

物理学Physics

A small and vigorous black hole in the early Universe

早期宇宙中一个小而有活力的黑洞

▲ 作者：Roberto Maiolino, Jan Scholtz, Joris Witstok, Stefano Carniani, Francesco D’Eugenio, Anna de Graaff, Hannah übler, Sandro Tacchella, Emma Curtis-Lake, Santiago Arribas, Andrew Bunker, Stéphane Charlot, Jacopo Chevallard, Mirko Curti, Tobias J. Looser, Michael V. Maseda, Timothy D. Rawle, Bruno Rodríguez del Pino, Chris J. Willott, Eiichi Egami, Daniel J. Eisenstein, Kevin N. Hainline, Brant Robertson, Christina C. Williams, Fengwu Sun

▲ 链接：

https://www.nature.com/articles/s41586-024-07052-5

▲ 摘要：

人们提出了几种理论来描述早期宇宙中黑洞种子的形成，并解释在大爆炸后的第一个十亿年中观测到的超大质量黑洞的出现。

模型考虑了不同的播种和吸积情景，这需要对大爆炸后最初几亿年的黑洞进行探测和表征才能得到验证。

研究者对GN-z11的JWST-NIRSpec光谱进行了广泛的分析，GN-z11是一个特别明亮的星系，在红移z = 10.6处。光谱特征表明GN-z11拥有一个吸积黑洞。研究解释了GN-z11的高亮度，也解释了其异常高的氮丰度。

▲ Abstract：

Several theories have been proposed to describe the formation of black hole seeds in the early Universe and to explain the emergence of very massive black holes observed in the first thousand million years after the Big Bang. Models consider different seeding and accretion scenarios, which require the detection and characterization of black holes in the first few hundred million years after the Big Bang to be validated. Here we present an extensive analysis of the JWST-NIRSpec spectrum of GN-z11. These spectral features indicate that GN-z11 hosts an accreting black hole. Our finding explains the high luminosity of GN-z11 and can also provide an explanation for its exceptionally high nitrogen abundance.

A rapidly time-varying equatorial jet in Jupiter’s deep interior

木星内部深处快速随时间变化的赤道喷流

▲ 作者：Jeremy Bloxham, Hao Cao, David J. Stevenson, John E. P. Connerney & Scott J. Bolton

▲ 链接：

https://www.nature.com/articles/s41586-024-07046-3

▲ 摘要：

行星磁场提供了一扇窗口，让人们得以了解行星内部深层的动力学。特别是，内部导电区域的流体流动与磁场之间的相互作用会引起外部观察到的磁场可观察的长期变化（时间依赖性）。

木星磁场的长期变化最近被揭示出来，并被证明部分是由赤道的轴对称喷流引起的。这种喷流是否与时间有关，以前还没有得到解决，但它对理解地球内部的动力学至关重要。如果稳定，它可能是深层发电机对流流动的表现（预计射流是该流动的一部分），但如果时间依赖于比几百年的对流周转时间短得多的时间尺度，它可能有不同的起源。

研究者展示了喷流有一个周期约为4年的波状波动，强烈暗示了木星金属氢内部存在扭振（一种围绕旋转轴的圆柱对称振荡流）或局域化的阿尔夫萨芬波。这为揭示金属氢区域内磁场的其他隐藏方面开辟了一条途径，从而限制了产生木星磁场的发电机。

▲ Abstract：

Planetary magnetic fields provide a window into the otherwise largely inaccessible dynamics of a planet’s deep interior. In particular, interaction between fluid flow in electrically conducting interior regions and the magnetic field there gives rise to observable secular variation (time dependency) of the externally observed magnetic field. Secular variation of Jupiter’s field has recently been revealed and been shown to arise, in part, from an axisymmetric, equatorial jet2. Whether this jet is time dependent has not previously been addressed, yet it is of critical importance for understanding the dynamics of the planet’s interior. If steady, it would probably be a manifestation of deep dynamo convective flow (and jets are anticipated as part of that flow) but if time dependent on a timescale much shorter than the convective turnover timescale of several hundred years, it would probably have a different origin. Here we show that the jet has a wavelike fluctuation with a period of roughly 4 years, strongly suggestive of the presence of a torsional oscillation (a cylindrically symmetric oscillating flow about the rotation axis) or a localized Alfvén wave in Jupiter’s metallic hydrogen interior. This opens a pathway towards revealing otherwise hidden aspects of the magnetic field within the metallic hydrogen region and hence constraining the dynamo that generates Jupiter’s magnetic field.

Integrated frequency-modulated optical parametric oscillator

集成调频光参量振荡器

▲ 作者：Hubert S. Stokowski, Devin J. Dean, Alexander Y. Hwang, Taewon Park, Oguz Tolga Celik, Timothy P. McKenna, Marc Jankowski, Carsten Langrock, Vahid Ansari, Martin M. Fejer & Amir H. Safavi-Naeini

▲ 链接：

https://www.nature.com/articles/s41586-024-07071-2

▲ 摘要：

研究者介绍了一种以前未知的微梳—— 一种结合了电光和参数放大的集成器件，从而产生调频光学参数振荡器（FM-OPO）。与其他解决方案相比，它不形成脉冲，但保持操作简单和高效的泵浦功率使用，输出类似于调频激光器。

研究者概述了该器件的工作原理，并通过在铌酸锂薄膜上制作完整的光学系统进行了演示。FM-OPO微梳提供强大的操作动态，高效率和宽带宽，有望用于计量、光谱学、电信、传感和计算的紧凑型精密工具。

▲ Abstract：

Here we introduce a previously unknown class of microcomb—an integrated device that combines electro-optics and parametric amplification to yield a frequency-modulated optical parametric oscillator (FM-OPO). In contrast to the other solutions, it does not form pulses but maintains operational simplicity and highly efficient pump power use with an output resembling a frequency-modulated laser. We outline the working principles of our device and demonstrate it by fabricating the complete optical system in thin-film lithium niobate. The FM-OPO microcomb offers robust operational dynamics, high efficiency and broad bandwidth, promising compact precision tools for metrology, spectroscopy, telecommunications, sensing and computing.

环境学Environics

Making cities mental health friendly for adolescents and young adults

让城市对青少年和年轻人的心理健康更友好

▲ 作者：Pamela Y. Collins, Moitreyee Sinha, Tessa Concepcion, George Patton, Thaisa Way, Layla McCay, Augustina Mensa-Kwao, Helen Herrman, Evelyne de Leeuw, Nalini Anand, Lukoye Atwoli, Nicole Bardikoff, Chantelle Booysen, Inés Bustamante, Yajun Chen, Kelly Davis, Tarun Dua, Nathaniel Foote, Matthew Hughsam, Damian Juma, Shisir Khanal, Manasi Kumar, Bina Lefkowitz, Peter McDermott, Lian Zeitz

▲ 链接：

https://www.nature.com/articles/s41586-023-07005-4

▲ 摘要：

城市生活影响城市居民的心理健康，虽然城市提供获得保健、教育和经济收益的机会，但城市环境往往不利于心理健康。未来30年，随着城市化进程的加快，居住在城市的儿童和青少年人口将不断增加。塑造城市生活中影响青少年心理健康的各个方面，可能对青少年的福祉和成人的发展轨迹产生巨大影响。

在这项研究中，一个多学科的全球研究人员、从业人员、倡导者和年轻人组成的小组，完成了顺序调查，以确定并优先考虑适合年轻人的心理健康友好型城市的特征。

研究展示了一组按个人、人际、社区、组织、政策和环境干预领域进行排序的特征陈述。个人发展的生活技能，重视和接受年轻人的想法和选择，为社会联系、就业和工作保障提供安全的公共空间，将青年投入城市规划和设计，以及解决不利的社会决定因素是各领域的优先事项。

研究结果强调了跨部门、多层次干预的必要性，以及对支持青少年心理健康的城市进行包容、公平、参与性设计的必要性。

▲ Abstract：

Urban life shapes the mental health of city dwellers, and although cities provide access to health, education and economic gain, urban environments are often detrimental to mental health. Increasing urbanization over the next three decades will be accompanied by a growing population of children and adolescents living in cities3. Shaping the aspects of urban life that influence youth mental health could have an enormous impact on adolescent well-being and adult trajectories4. We invited a multidisciplinary, global group of researchers, practitioners, advocates and young people to complete sequential surveys to identify and prioritize the characteristics of a mental health-friendly city for young people. Here we show a set of ranked characteristic statements, grouped by personal, interpersonal, community, organizational, policy and environmental domains of intervention. Life skills for personal development, valuing and accepting young people’s ideas and choices, providing safe public space for social connection, employment and job security, centring youth input in urban planning and design, and addressing adverse social determinants were priorities by domain. Our findings highlight the need for intersectoral, multilevel intervention and for inclusive, equitable, participatory design of cities that support youth mental health.

Disappearing cities on US coasts

美国沿海城市正在消失

▲ 作者：Leonard O. Ohenhen, Manoochehr Shirzaei, Chandrakanta Ojha, Sonam F. Sherpa & Robert J. Nicholls

▲ 链接：

https://www.nature.com/articles/s41586-024-07038-3

▲ 摘要：

预计到2050年，美国海岸线的海平面将上升0.25-0.3米，这增加了主要城市发生更具破坏性的洪水和淹没的可能性。

然而，这些影响可能会因沿海地区的下沉而加剧，这一因素在沿海管理政策和长期城市规划中往往没有得到充分的体现。研究者将高分辨率垂直陆地运动（即陆地上升或下降）和高程数据集与海平面上升预测相结合，量化了美国32个主要沿海城市的潜在淹没区域。

研究表明，即使考虑到目前的海防结构，到2050年，1006至1389平方公里之间的土地面积将受到相对海平面上升的威胁，对55,000-273,000人口和31,000-171,000财产构成威胁。

分析表明，不考虑城市内部空间变化的地面沉降可能导致预期暴露的预测不准确。这些潜在的后果显示了适应挑战的规模，这在大多数美国沿海城市都没有得到重视。

▲ Abstract：

The sea level along the US coastlines is projected to rise by 0.25–0.3?m by 2050, increasing the probability of more destructive flooding and inundation in major cities. However, these impacts may be exacerbated by coastal subsidence—the sinking of coastal land areas—a factor that is often underrepresented in coastal-management policies and long-term urban planning. In this study, we combine high-resolution vertical land motion (that is, raising or lowering of land) and elevation datasets with projections of sea-level rise to quantify the potential inundated areas in 32 major US coastal cities. Here we show that, even when considering the current coastal-defence structures, further land area of between 1,006 and 1,389?km2 is threatened by relative sea-level rise by 2050, posing a threat to a population of 55,000–273,000 people and 31,000–171,000 properties. Our analysis shows that not accounting for spatially variable land subsidence within the cities may lead to inaccurate projections of expected exposure. These potential consequences show the scale of the adaptation challenge, which is not appreciated in most US coastal cities.

Rainforest transformation reallocates energy from green to brown food webs

雨林的转变将能量从绿色食物网重新分配到棕色食物网

▲ 作者：Anton M. Potapov, Jochen Drescher, Kevin Darras, Arne Wenzel, Noah Janotta, Rizky Nazarreta, Kasmiatun, Valentine Laurent, Amanda Mawan, Endah H. Utari, Melanie M. Pollierer, Katja Rembold, Rahayu Widyastuti, Damayanti Buchori, Purnama Hidayat, Edgar Turner, Ingo Grass, Catrin Westphal, Teja Tscharntke & Stefan Scheu

▲ 链接：

https://www.nature.com/articles/s41586-024-07083-y

▲ 摘要：

由于土地利用的变化，陆生动物的生物多样性正在日益丧失。然而，在超级多样化的热带生态系统中，地上和地下以及跨营养水平的功能和能量后果在很大程度上仍然未知。

为了填补这一空白，研究者评估了印度尼西亚苏门答腊岛热带雨林和种植园中地上“绿色”（树冠节肢动物和鸟类）和地下“棕色”（土壤节肢动物和蚯蚓）动物食物网的能量通量变化。

研究表明，热带雨林中的大部分能量被输送到地下动物食物网。与雨林相比，油棕和橡胶人工林的动物总能量通量相似，或者在橡胶混农林的情况下，动物总能量通量更高，但关键能量节点明显不同：在雨林中，超过90%的动物总能量通量由土壤和冠层中的节肢动物引导，而在人工林中，超过50%的能量分配给环节动物（蚯蚓）。

土地利用变化导致地上多营养能量通量持续下降，而地下食物网的响应是能量通量减少到更高的营养水平，下降到- 90%，从慢能量通道（真菌）转向快能量通道（细菌），从粪便产生转向土壤有机质消耗。这与先前报道的土壤碳储量枯竭相吻合。

研究表明，有充分证据表明，热带土地利用变化导致动物生物多样性下降，这与地上和地下生态系统间食物网的巨大能量和功能重构有关。

▲ Abstract：

Terrestrial animal biodiversity is increasingly being lost because of land-use change1,2. However, functional and energetic consequences aboveground and belowground and across trophic levels in megadiverse tropical ecosystems remain largely unknown. To fill this gap, we assessed changes in energy fluxes across ‘green’ aboveground (canopy arthropods and birds) and ‘brown’ belowground (soil arthropods and earthworms) animal food webs in tropical rainforests and plantations in Sumatra, Indonesia. Our results showed that most of the energy in rainforests is channelled to the belowground animal food web. Oil palm and rubber plantations had similar or, in the case of rubber agroforest, higher total animal energy fluxes compared to rainforest but the key energetic nodes were distinctly different: in rainforest more than 90% of the total animal energy flux was channelled by arthropods in soil and canopy, whereas in plantations more than 50% of the energy was allocated to annelids (earthworms). Land-use change led to a consistent decline in multitrophic energy flux aboveground, whereas belowground food webs responded with reduced energy flux to higher trophic levels, down to ?90%, and with shifts from slow (fungal) to fast (bacterial) energy channels and from faeces production towards consumption of soil organic matter. This coincides with previously reported soil carbon stock depletion. Here we show that well-documented animal biodiversity declines with tropical land-use change are associated with vast energetic and functional restructuring in food webs across aboveground and belowground ecosystem compartments.