編譯 | 馮維維
Nature , Volume 627 Issue 8002, 7 March 2024
【自然】 第627卷，8002期，2024年3月7日
物理學 Physics
A small and vigorous black hole in the early Universe
早期宇宙中一個小而有活力的黑洞
▲ 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
▲ 連結：
https://www.nature.com/articles/s41586-024-07052-5
▲ 摘要：
人們提出了幾種理論來描述早期宇宙中黑洞種子的形成，並解釋在大爆炸後的第一個十億年中觀測到的超大質素黑洞的出現。
模型考慮了不同的播種和吸積情景，這需要對大爆炸後最初幾億年的黑洞進行探測和表征才能得到驗證。
研究者對GN-z11的JWST-NIRSpec光譜進行了廣泛的分析，GN-z11是一個特別明亮的星系，在紅移z = 10.6處。光譜特征表明GN-z11擁有一個吸積黑洞。研究解釋了GN-z11的高亮度，也解釋了其異常高的氮豐度。
▲ 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
木星內部深處快速隨時間變化的赤道噴流
▲ 作者：Jeremy Bloxham, Hao Cao, David J. Stevenson, John E. P. Connerney & Scott J. Bolton
▲ 連結：
https://www.nature.com/articles/s41586-024-07046-3
▲ 摘要：
行星磁場提供了一扇視窗，讓人們得以了解行星內部深層的動力學。特別是，內部導電區域的流體流動與磁場之間的相互作用會引起外部觀察到的磁場可觀察的長期變化（時間依賴性）。
木星磁場的長期變化最近被揭示出來，並被證明部份是由赤道的軸對稱噴流引起的。這種噴流是否與時間有關，以前還沒有得到解決，但它對理解地球內部的動力學至關重要。如果穩定，它可能是深層發電機對流流動的表現（預計射流是該流動的一部份），但如果時間依賴於比幾百年的對流周轉時間短得多的時間尺度，它可能有不同的起源。
研究者展示了噴流有一個周期約為4年的波狀波動，強烈暗示了木星金屬氫內部存在扭振（一種圍繞旋轉軸的圓柱對稱振蕩流）或局域化的阿爾夫薩芬波。這為揭示金屬氫區域內磁場的其他隱藏方面開辟了一條途徑，從而限制了產生木星磁場的發電機。
▲ 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
整合調頻光參量振蕩器
▲ 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
▲ 連結：
https://www.nature.com/articles/s41586-024-07071-2
▲ 摘要：
研究者介紹了一種以前未知的微梳—— 一種結合了電光和參數放大的整合器件，從而產生調頻光學參數振蕩器（FM-OPO）。與其他解決方案相比，它不形成脈沖，但保持操作簡單和高效的泵浦功率使用，輸出類似於調頻激光器。
研究者概述了該器件的工作原理，並透過在鈮酸鋰薄膜上制作完整的光學系統進行了演示。FM-OPO微梳提供強大的操作動態，高效率和寬頻寬，有望用於計量、光譜學、電信、傳感和計算的緊湊型精密工具。
▲ 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.
環境學 Environics
Making cities mental health friendly for adolescents and young adults
讓城市對青少年和年輕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
▲ 連結：
https://www.nature.com/articles/s41586-023-07005-4
▲ 摘要：
城市生活影響城市居民的心理健康，雖然城市提供獲得保健、教育和經濟收益的機會，但城市環境往往不利於心理健康。未來30年，隨著城市化行程的加快，居住在城市的兒童和青少年人口將不斷增加。塑造城市生活中影響青少年心理健康的各個方面，可能對青少年的福祉和成人的發展軌跡產生巨大影響。
在這項研究中，一個多學科的全球研究人員、從業人員、倡導者和年輕人組成的小組，完成了順序調查，以確定並優先考慮適合年輕人的心理健康友好型城市的特征。
研究展示了一組按個人、人際、社區、組織、政策和環境幹預領域進行排序的特征陳述。個人發展的生活技能，重視和接受年輕人的想法和選擇，為社會聯系、就業和工作保障提供安全的公共空間，將青年投入城市規劃和設計，以及解決不利的社會決定因素是各領域的優先事項。
研究結果強調了跨部門、多層次幹預的必要性，以及對支持青少年心理健康的城市進行包容、公平、參與性設計的必要性。
▲ 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.
美國沿海城市正在消失
▲ 作者：Leonard O. Ohenhen, Manoochehr Shirzaei, Chandrakanta Ojha, Sonam F. Sherpa & Robert J. Nicholls
▲ 連結：
https://www.nature.com/articles/s41586-024-07038-3
▲ 摘要：
預計到2050年，美國海岸線的海平面將上升0.25-0.3米，這增加了主要城市發生更具破壞性的洪水和淹沒的可能性。
然而，這些影響可能會因沿海地區的下沈而加劇，這一因素在沿海管理政策和長期城市規劃中往往沒有得到充分的體現。研究者將高分辨率垂直陸地運動（即陸地上升或下降）和高程數據集與海平面上升預測相結合，量化了美國32個主要沿海城市的潛在淹沒區域。
研究表明，即使考慮到目前的海防結構，到2050年，1006至1389平方公裏之間的土地面積將受到相對海平面上升的威脅，對55,000-273,000人口和31,000-171,000財產構成威脅。
分析表明，不考慮城市內部空間變化的地面沈降可能導致預期暴露的預測不準確。這些潛在的後果顯示了適應挑戰的規模，這在大多數美國沿海城市都沒有得到重視。
▲ 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
雨林的轉變將能量從綠色食物網重新分配到棕色食物網
▲ 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
▲ 連結：
https://www.nature.com/articles/s41586-024-07083-y
▲ 摘要：
由於土地利用的變化，陸生動物的生物多樣性正在日益喪失。然而，在超級多樣化的熱帶生態系中，地上和地下以及跨營養水平的功能和能量後果在很大程度上仍然未知。
為了填補這一空白，研究者評估了印度尼西亞蘇門答臘島熱帶雨林和種植園中地上「綠色」（樹冠節肢動物和鳥類）和地下「棕色」（土壤節肢動物和蚯蚓）動物食物網的能量通量變化。
研究表明，熱帶雨林中的大部份能量被輸送到地下動物食物網。與雨林相比，油棕和橡膠人工林的動物總能量通量相似，或者在橡膠混農林的情況下，動物總能量通量更高，但關鍵能量節點明顯不同：在雨林中，超過90%的動物總能量通量由土壤和冠層中的節肢動物引導，而在人工林中，超過50%的能量分配給環節動物（蚯蚓）。
土地利用變化導致地上多營養能量通量持續下降，而地下食物網的響應是能量通量減少到更高的營養水平，下降到- 90%，從慢能量通道（真菌）轉向快能量通道（細菌），從糞便產生轉向土壤有機質消耗。這與先前報道的土壤碳儲量枯竭相吻合。
研究表明，有充分證據表明，熱帶土地利用變化導致動物生物多樣性下降，這與地上和地下生態系間食物網的巨大能量和功能重構有關。
▲ 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.
