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发布日期：2024-10-16 作者：开云
One month convection timescale on the surface of a giant evolved star
演变巨恒星概况对流时候标准为1个月
▲作者：Wouter Vlemmings, Theo Khouri, Behzad Bojnordi Arbab, Elvire De Beck Matthias Maercker
▲链接：
https://www.nature.com/articles/s41586-024-07836-9
▲摘要：
在恒星演变的很多阶段，能量的对传播输都很主要，这在太阳或庞大的演变恒星中已获得了很好的研究。在年夜质量红超巨星的概况也发现了对流的特点。一样，对低质量演变的恒星，也发现了对流的迹象，但对流的时候标准和巨细依然没有获得很好的限制。
模子注解，对流活动对发生强风相当主要，强风使恒星核合成的产品返回到星际介质中。研究者陈述了一系列重建的干与丈量图象的概况演化的巨星R剑鱼座。这些图象揭露了一个具有凸起的小标准特点的星盘，它供给了恒星概况对流的布局和活动。
他们发现恒星盘上特点的主导布局尺寸为0.72±0.05天文单元。他们丈量到地表活动的速度在- 18和+20 km s - 1之间转变，这意味着对流的时候标准年夜约是一个月。这注解低质量和高质量演变恒星的对流特征之间可能存在差别。
▲ Abstract：
The transport of energy through convection is important during many stages of stellar evolution, and is best studied in our Sun or giant evolved stars. Features that are attributed to convection are found on the surface of massive red supergiant stars. Also for lower-mass evolved stars, indications of convection are found, but convective timescales and sizes remain poorly constrained. Models indicate that convective motions are crucial to produce strong winds that return the products of stellar nucleosynthesis into the interstellar medium. Here we report a series of reconstructed interferometric images of the surface of the evolved giant star R?Doradus. The images reveal a stellar disk with prominent small-scale features that provide the structure and motions of convection on the stellar surface. We find that the dominant structure size of the features on the stellar disk is 0.72?±?0.05 astronomical units. We measure the velocity of the surface motions to vary between ?18 and +20?km?s?1, which means that the convective timescale is approximately one month. This indicates a possible difference between the convection properties of low-mass and high-mass evolved stars.
Spectroscopic confirmation of two luminous galaxies at a redshift of 14
两个红移为14的发光星系
▲作者：Stefano Carniani, Kevin Hainline, Francesco D’Eugenio, Daniel J. Eisenstein, Peter Jakobsen, Joris Witstok, Benjamin D. Johnson, Jacopo Chevallard, Roberto Maiolino, Jakob M. Helton, Chris Willott, Brant Robertson, Stacey Alberts, Santiago Arribas, William M. Baker, Rachana Bhatawdekar, Kristan Boyett, Andrew J. Bunker, Alex J. Cameron, Phillip A. Cargile, Stéphane Charlot, Mirko Curti, Emma Curtis-Lake, Eiichi Egami, Christopher N. A. Willmer Show authors
▲链接：
https://www.nature.com/articles/s41586-024-07860-9
▲摘要：
詹姆斯 韦布太空千里镜初次不雅测的红移为z≈13的星系，完全改变了人们对宇宙的理解。另外，“拂晓”号探测器发现的很多发光星系（z 10）注解，星系成长敏捷，与很多尺度模子存在较着的张力。但是，这些星系年夜多缺少光谱确认，是以它们的距离和性质是不肯定的。
研究者展现了韦布进步前辈深河外巡天—近红外光谱仪对两个发光星系在和z = 13.90±0.17处的光谱确认。光谱显示紫外持续带较着的莱曼α断裂，但没有探测到发射线。
这一发现证实，在宇宙年夜爆炸后3亿年，发光星系就已存在了，并且比在韦布之前预期的要遍及很多。这两个星系中最遥远的阿谁出乎料想地敞亮，其空间分辩半径为260秒差距。再斟酌到第二个星系很是峻峭的紫外线斜率，研究者认为，这两个星系都是由恒星持续辐射主导的，这注解初期宇宙中发光星系的多余不克不及完全用黑洞的吸积来注释。星系构成模子需要解决在宇宙汗青的初期存在如斯庞大和敞亮的星系的问题。
▲ Abstract：
The first observations of the James Webb Space Telescope (JWST) have revolutionized our understanding of the Universe by identifying galaxies at redshift z?≈?13 . In addition, the discovery of many luminous galaxies at Cosmic Dawn (z? ?10) has suggested that galaxies developed rapidly, in apparent tension with many standard models. However, most of these galaxies lack spectroscopic confirmation, so their distances and properties are uncertain. Here we present JWST Advanced Deep Extragalactic Survey–Near-Infrared Spectrograph spectroscopic confirmation of two luminous galaxies at and z?=?13.90?±?0.17. The spectra reveal ultraviolet continua with prominent Lyman-α breaks but no detected emission lines. This discovery proves that luminous galaxies were already in place 300?million years after the Big Bang and are more common than what was expected before JWST. The most distant of the two galaxies is unexpectedly luminous and is spatially resolved with a radius of 260?parsecs. Considering also the very steep ultraviolet slope of the second galaxy, we conclude that both are dominated by stellar continuum emission, showing that the excess of luminous galaxies in the early Universe cannot be entirely explained by accretion onto black holes. Galaxy formation models will need to address the existence of such large and luminous galaxies so early in cosmic history.
Observing the two-dimensional Bose glass in an optical quasicrystal
在光学准晶体中不雅察二维玻色玻璃
▲作者：Jr-Chiun Yu, Shaurya Bhave, Lee Reeve, Bo Song Ulrich Schneider
▲链接：
https://www.nature.com/articles/s41586-024-07875-2
▲摘要：
无序的存在本色上影响了物理系统的行动。它可以引发慢动力学或玻璃动力学，或完全按捺输运，如在安德森绝缘体中，凡是扩大的波函数，如光场或电子布洛赫波变得指数局域化。无序和彼此感化的综合效应是丰硕的凝集态物理的焦点。
在玻色子系统中，它也能够致使额外的量子态，如玻色玻璃——一种在无序玻色子系统中呈现的没有长程相相关的绝缘但可紧缩的状况，与尽人皆知的彼此感化玻色子的超流体和莫特绝缘基态分歧。研究者报导了在八重对称准晶体光学晶格中利用超冷原子的二维玻色玻璃的尝试实现。经由过程探测系统的相关性，他们不雅察到玻色玻璃到超流体的改变，并绘制了弱彼此感化状况下的相图。
研究进一步证实了在典型的尝试时候标准上不成能绝热穿越玻色玻璃，经由过程查抄恢复相关性的能力，并会商了与玻色玻璃预期的非遍历性的联系。该不雅察成果与比来的量子蒙特卡罗猜测很是吻合，为尝试测试玻色玻璃、多体局域化和玻璃动力学之间的联系摊平了道路。
▲ Abstract：
The presence of disorder substantially influences the behaviour of physical systems. It can give rise to slow or glassy dynamics, or to a complete suppression of transport as in Anderson insulators, where normally extended wavefunctions such as light fields or electronic Bloch waves become exponentially localized. The combined effect of disorder and interactions is central to the richness of condensed-matter physics. In bosonic systems, it can also lead to additional quantum states such as the Bose glass—an insulating but compressible state without long-range phase coherence that emerges in disordered bosonic systems and is distinct from the well-known superfluid and Mott insulating ground states of interacting bosons. Here we report the experimental realization of the two-dimensional Bose glass using ultracold atoms in an eight-fold symmetric quasicrystalline optical lattice. By probing the coherence properties of the system, we observe a Bose-glass-to-superfluid transition and map out the phase diagram in the weakly interacting regime. We furthermore demonstrate that it is not possible to adiabatically traverse the Bose glass on typical experimental timescales by examining the capability to restore coherence and discuss the connection to the expected non-ergodicity of the Bose glass. Our observations are in good agreement with recent quantum Monte Carlo predictions6 and pave the way for experimentally testing the connection between the Bose glass, many-body localization and glassy dynamics more generally.
Global marine microbial diversity and its potential in bioprospecting
全球海洋微生物多样性和其在生物勘察中的潜力
▲作者：Jianwei Chen, Yangyang Jia, Ying Sun, Kun Liu, Changhao Zhou, Chuan Liu, Denghui Li, Guilin Liu, Chengsong Zhang, Tao Yang, Lei Huang, Yunyun Zhuang, Dazhi Wang, Dayou Xu, Qiaoling Zhong, Yang Guo, Anduo Li, Inge Seim, Ling Jiang, Lushan Wang, Simon Ming Yuen Lee, Yujing Liu, Dantong Wang, Guoqiang Zhang,Guangyi Fan Show authors
▲链接：
https://www.nature.com/articles/s41586-024-07891-2
▲摘要：
曩昔二十年，从海洋系统中检索到的微生物基因组数目显著增添。但是，将这类海洋基因组多样性转化为生物手艺和生物医学利用依然具有挑战性。研究者从公然的海洋宏基因组中恢复了43191个细菌和古细菌基因组，包罗138个分歧门的普遍多样性，从头界说了海洋细菌基因组巨细的上限，并揭露了基因编纂CRISPR-Cas系统和抗生素抗性基因之间的复杂衡量。
对这些海洋基因组的硅生物勘察致使发现了一种新的CRISPR-Cas9系统，10种抗菌肽和3种降解聚对苯二甲酸乙二醇酯的酶。体外尝试证实了其有用性和疗效。这项工作证实，全球范围的测序打算增进了人们对微生物多样性若何在海洋中进化和保持的理解，并证实了若何可延续地操纵这些打算来推动生物手艺和生物医学。
▲ Abstract：
The past two decades has witnessed a remarkable increase in the number of microbial genomes retrieved from marine systems. However, it has remained challenging to translate this marine genomic diversity into biotechnological and biomedical applications. Here we recovered 43,191 bacterial and archaeal genomes from publicly available marine metagenomes, encompassing a wide range of diversity with 138 distinct phyla, redefining the upper limit of marine bacterial genome size and revealing complex trade-offs between the occurrence of CRISPR–Cas systems and antibiotic resistance genes. In silico bioprospecting of these marine genomes led to the discovery of a novel CRISPR–Cas9 system, ten antimicrobial peptides, and three enzymes that degrade polyethylene terephthalate. In vitro experiments confirmed their effectiveness and efficacy. This work provides evidence that global-scale sequencing initiatives advance our understanding of how microbial diversity has evolved in the oceans and is maintained, and demonstrates how such initiatives can be sustainably exploited to advance biotechnology and biomedicine.
Ancient Rapanui genomes reveal resilience and pre-European contact with the Americas
古基因组揭露拉帕努伊人的顺应力和与美洲的接触
▲作者：J. Víctor Moreno-Mayar, Bárbara Sousa da Mota, Tom Higham, Signe Klemm, Moana Gorman Edmunds, Jesper Stenderup, Miren Iraeta-Orbegozo, Véronique Laborde, Evelyne Heyer, Francisco Torres Hochstetter, Martin Friess, Morten E. Allentoft, Hannes Schroeder, Olivier Delaneau Anna-Sapfo Malaspinas
▲链接：
https://www.nature.com/articles/s41586-024-07881-4
▲摘要：
拉帕努伊岛（也被称为新生节岛）是世界上最孤立的有人栖身的处所之一。它的考古记实吸引了很多人的想象力，此中包罗被称为“摩艾”的标记性巨石雕像。对拉帕努伊岛的普遍研究发生了两个凸起的争辩。
起首，拉帕努伊人的汗青被描写为一个资本过度开辟的正告故事，终究致使了生齿的年夜范围解体——“生态灭尽”理论。其次，在与欧洲人接触之前，跨承平洋航行到美洲的可能性依然存在争议。
为领会决这些争议，研究者基在15个古老的拉帕努伊人个别重建了拉帕努伊人的基因组汗青。他们对这些个别进行了放射性碳测定和全基因组测序，发现这些人来自波利尼西亚人，与此刻的拉帕努伊人关系最紧密亲密。经由过程有用的种群范围重建和普遍的种群遗传学摹拟，研究者否认了生态灭尽理论提出的17世纪严重种群瓶颈的情形。
另外，古代和此刻的拉帕努伊人携带着类似比例的美洲原居民夹杂物（约10%）。操纵贝叶斯方式综合遗传和放射性碳年月，他们估量这一夹杂事务产生在公元1250~1430年。
▲ Abstract：
Rapa Nui (also known as Easter Island) is one of the most isolated inhabited places in the world. It has captured the imagination of many owing to its archaeological record, which includes iconic megalithic statues called moai. Two prominent contentions have arisen from the extensive study of Rapa Nui. First, the history of the Rapanui has been presented as a warning tale of resource overexploitation that would have culminated in a major population collapse—the ‘ecocide’ theory. Second, the possibility of trans-Pacific voyages to the Americas pre-dating European contact is still debated. Here, to address these questions, we reconstructed the genomic history of the Rapanui on the basis of 15 ancient Rapanui individuals that we radiocarbon dated (1670–1950?CE) and whole-genome sequenced (0.4–25.6×). We find that these individuals are Polynesian in origin and most closely related to present-day Rapanui, a finding that will contribute to repatriation efforts. Through effective population size reconstructions and extensive population genetics simulations, we reject a scenario involving a severe population bottleneck during the 1600s, as proposed by the ecocide theory. Furthermore, the ancient and present-day Rapanui carry similar proportions of Native American admixture (about 10%). Using a Bayesian approach integrating genetic and radiocarbon dates, we estimate that this admixture event occurred about 1250–1430?CE.
Closed-loop transfer enables artificial intelligence to yield chemical knowledge
闭环转移令人工智能发生化学常识
▲作者：Nicholas H. Angello, David M. Friday, Changhyun Hwang, Seungjoo Yi, Austin H. Cheng, Tiara C. Torres-Flores, Edward R. Jira, Wesley Wang, Alán Aspuru-Guzik, Martin D. Burke, Charles M. Schroeder, Ying Diao Nicholas E. Jackson
▲链接：
https://www.nature.com/articles/s41586-024-07892-1
▲摘要：
人工智能指导的闭环尝试已成为优化方针函数的一种很有前程的方式，但这开云体育app类传统的黑箱方式在发现新化学常识方面的庞大潜力仍未获得很年夜水平的开辟。研究者陈述了闭环尝试与基在物理的特点选择和监视进修的集成，称为闭环转移（CLT），以发生与方针函数优化并行的化学看法。
CLT用在研究各类有电机子利用中利用的光搜集供体—受体份子溶液中的光不变性身分，并显示了包罗三重态流形的高能区域的主要性在内的根基看法。这是可能的主动化模块化合成和尝试表征，只有年夜约1.5%的理论化学空间。经由过程多个尝试测试集，并经由过程调剂溶剂的三重态激起态能量，在闭环光不变性优化进程中冲破不雅察到的平台，验证了该物理信息模子的光不变性。
CLT在其他材料系统中的进一步利用撑持了该策略在加强闭环策略中的推行。总的来讲，这些发现注解，将可注释的监视进修模子和基在物理的特点与闭环发现进程相连系，可以快速供给根基的化学看法。
▲ Abstract：
Artificial intelligence-guided closed-loop experimentation has emerged as a promising method for optimization of objective functions, but the substantial potential of this traditionally black-box approach to uncovering new chemical knowledge has remained largely untapped. Here we report the integration of closed-loop experiments with physics-based feature selection and supervised learning, denoted as closed-loop transfer (CLT), to yield chemical insights in parallel with optimization of objective functions. CLT was used to examine the factors dictating the photostability in solution of light-harvesting donor–acceptor molecules used in a variety of organic electronics applications, and showed fundamental insights including the importance of high-energy regions of the triplet state manifold. This was possible following automated modular synthesis and experimental characterization of only around 1.5% of the theoretical chemical space. This physics-informed model for photostability was strengthened using multiple experimental test sets and validated by tuning the triplet excited-state energy of the solvent to break out of the observed plateau in the closed-loop photostability optimization process. Further applications of CLT to additional materials systems support the generalizability of this strategy for augmenting closed-loop strategies. Broadly, these findings show that combining interpretable supervised learning models and physics-based features with closed-loop discovery processes can rapidly provide fundamental chemical insights.