Science, 11 November 2022, Volume 387 Issue 6620
《科学》2022年11月11日，第387卷，6620期
天文学Astronomy
Polarized x-rays constrain the disk-jet geometry in the black hole x-ray binary Cygnus X-1
偏振x射线限制了黑洞x射线双星天鹅座X-1中的盘喷流几何结构
▲ 作者：HENRIC KRAWCZYNSKI, FABIO MULERI , MICHAL DOVČIAK et al.
▲ 链接：
https://www.science.org/doi/10.1126/science.add5399
▲ 摘要：
黑洞x射线双星（XRB）系统的形成是由于气体从正常恒星中剥离出来，并吸积到黑洞上时，黑洞将气体加热到足以发射x射线。
我们报告了使用成像x射线偏振测量探索者对XRB天鹅座X-1的偏振观测。电场位置角与流出的射流对齐，表明射流是从内部x射线发射区域发射的。2～8千电子伏的极化度为4.01±0.20%，表明吸积盘比二元轨道更接近于面朝。
这些观测结果表明，热x射线发射等离子体在空间上是垂直于而不是平行于喷流轴的平面上扩展的。
▲ Abstract：
A black hole x-ray binary (XRB) system forms when gas is stripped from a normal star and accretes onto a black hole, which heats the gas sufficiently to emit x-rays. We report a polarimetric observation of the XRB Cygnus X-1 using the Imaging X-ray Polarimetry Explorer. The electric field position angle aligns with the outflowing jet, indicating that the jet is launched from the inner x-ray–emitting region. The polarization degree is 4.01 ± 0.20% at 2 to 8 kiloelectronvolts, implying that the accretion disk is viewed closer to edge-on than the binary orbit. These observations reveal that hot x-ray–emitting plasma is spatially extended in a plane perpendicular to, not parallel to, the jet axis.
A limit on variations in the fine-structure constant from spectra of nearby Sun-like stars
类太阳恒星光谱中精细结构常数变化的极限
▲ 作者：MICHAEL T. MURPHY, DANIEL A. BERKE, FAN LIU(刘凡) et al.
▲ 链接：
https://www.science.org/doi/10.1126/science.abi9232
▲ 摘要：
精细结构常数α决定了电磁力的强度。它具备变化的可能，粒子物理的标准模型不能为其价值提供任何解释。恒星吸收线的波长依赖于α，但也受恒星大气中天体物理过程的系统影响。
我们从17颗恒星的观测中精确测量了线波长，这些恒星的大气特性与太阳几乎相同，这减少了系统效应。我们发现，在距离地球50秒差距的范围内，α的变化幅度小于等于十亿分之50。结合所有17颗恒星的结果，为恒星α的测量提供了一个经验的局部参考，集合精度为十亿分之12。
▲ Abstract：
The fine structure constant α sets the strength of the electromagnetic force. The Standard Model of particle physics provides no explanation for its value, which could potentially vary. The wavelengths of stellar absorption lines depend on α but are subject to systematic effects owing to astrophysical processes in stellar atmospheres. We measured precise line wavelengths from observations of 17 stars, selected to have almost identical atmospheric properties to those of the Sun (solar twins), which reduces those systematic effects. We found that α varies by ≲50 parts per billion within 50 parsecs from Earth. Combining the results from all 17 stars provides an empirical local reference for stellar measurements of α, with an ensemble precision of 12 parts per billion.
材料科学Materials Science
Inhibiting creep in nanograined alloys with stable grain boundary networks
驰豫晶界网络显著抵抗金属高温蠕变
▲ 作者：B. B. ZHANG, Y. G. TANG, Q. S. MEI, X. Y. LI AND K. LU
▲ 链接：
https://www.science.org/doi/10.1126/science.abq7739
▲ 摘要：
在此，我们报告了一种通过使用驰豫的晶界网络来抑制蠕动的不同策略。塑性变形触发了纳米颗粒单相镍钴铬合金中高密度晶界的结构弛豫，形成了与丰富孪晶边界互锁的驰豫晶界网络。
驰豫的晶界网络有效抑制了高温下的扩散蠕变过程。我们获得了前所未有的抗蠕变能力，在700°C（约61%熔点）、1GPa下，蠕变速率约为10-7/s，优于传统高温合金。
▲ Abstract：
We report a different strategy to inhibiting creep by use of stable GB networks. Plastic deformation triggered structural relaxation of high-density GBs in nanograined single-phased nickel-cobalt-chromium alloys, forming networks of stable GBs interlocked with abundant twin boundaries. The stable GB networks effectively inhibit diffusional creep processes at high temperatures. We obtained an unprecedented creep resistance, with creep rates of ~10–7 per second under gigapascal stress at 700°C (~61% melting point), outperforming that of conventional superalloys.
地球科学Geoscience
Subnational implications from climate and air pollution policies in India’s electricity sector
气候及应对空气污染的政策对印度电力行业的次国家影响
▲ 作者：SHAYAK SENGUPTA, PETER J. ADAMS, THOMAS A. DEETJEN et al.
▲ 链接：
https://www.science.org/doi/10.1126/science.abh1484
▲ 摘要：
在印度，温室气体和空气污染物的排放是气候变化和健康损害的重要原因。这项研究估计了印度电力部门目前的排放量，并模拟了气候变化和空气污染政策在邦一级的影响。
我们发现：1. 碳税对短期减排效果甚微，没有足够的可分配的低排放闲置产能来替代煤炭；2. 转向区域排放市场而不是邦一级的排放决策不会导致减排；3. 在国家层面上有适度影响的排放政策，在邦层面上却有不同的影响；4. 与生产或消费挂钩的定价或激励机制，将给各个邦带来显著不同的成本。
▲ Abstract：
Emissions of greenhouse gases and air pollutants in India are important contributors to climate change and health damages. This study estimates current emissions from India’s electricity sector and simulates the state-level implications of climate change and air pollution policies. We find that (i) a carbon tax results in little short-term emissions reductions because there is not enough dispatchable lower emission spare capacity to substitute coal; (ii) moving toward regional dispatch markets rather than state-level dispatch decisions will not lead to emissions reductions; (iii) policies that have modest emissions effects at the national level nonetheless have disparate state-level emissions impacts; and (iv) pricing or incentive mechanisms tied to production or consumption will result in markedly different costs to states.
Intensification of subhourly heavy rainfall
一小时内强降雨加剧
▲ 作者：HOOMAN AYAT, JASON P. EVANS, STEVEN C. SHERWOOD, AND JOSHUA SODERHOLM
▲ 链接：
https://www.science.org/doi/10.1126/science.abn8657
▲ 摘要：
在此，尽管没有证据表明每小时或每日尺度的情况，我们展示了澳大利亚悉尼附近20年来每10年至少20%的一小时内极端降雨量的强劲正趋势。在使用多个独立地面雷达跟踪的风暴中，可以看到这种趋势，虽然与雨量计数据一致，但似乎与已知的自然变化无关。
这一发现表明，一小时内极端降水的增加速度可能远远快于其他被报告过的时间尺度。
▲ Abstract：
Here, we show a robust positive trend of at least 20% per decade in subhourly extreme rainfall near Sydney, Australia, over 20 years, despite no evidence of trends at hourly or daily scales. This trend is seen consistently in storms tracked using multiple independent ground radars, is consistent with rain-gauge data, and does not appear to be associated with known natural variations. This finding suggests that subhourly rainfall extremes may be increasing substantially faster than those on more widely reported time scales.
生物学Biology
Seventy years of tunas, billfishes, and sharks as sentinels of global ocean health
七十年来，金枪鱼、长嘴鱼和鲨鱼成为全球海洋健康的哨兵
▲ 作者：MARIA JOSÉ JUAN-JORDÁ, HILARIO MURUA, HARITZ ARRIZABALAGA et al.
▲ 链接：
https://www.science.org/doi/10.1126/science.abj0211
▲ 摘要：
渔业活动受到越来越多的密切监测，但其对生物多样性的影响尚未得到同等重视。利用金枪鱼、长嘴鱼和鲨鱼等标志性的、经过充分研究的鱼类物种，我们计算了70年来灭绝风险年度变化的红色清单指数，以跟踪全球可持续发展和生物多样性目标的进展。
我们的研究表明，这一公认的生物多样性指标对捕捞死亡率高度敏感和响应。在经过约58年不断增加的灭绝风险后，有效的渔业管理已经改变了金枪鱼和长嘴鱼的生物多样性损失曲线，而鲨鱼的生物多样性损失曲线继续恶化，因为针对它们的管理严重不足。
在重建极具价值的商业鱼类种群的同时，下一个管理挑战是制止和扭转这些渔业对广泛的海洋生物多样性造成的损害。
▲ Abstract：
Fishing activity is closely monitored to an increasing degree, but its effects on biodiversity have not received such attention. Using iconic and well-studied fish species such as tunas, billfishes, and sharks, we calculate a continuous Red List Index of yearly changes in extinction risk over 70 years to track progress toward global sustainability and biodiversity targets. We show that this well-established biodiversity indicator is highly sensitive and responsive to fishing mortality. After ~58 years of increasing risk of extinction, effective fisheries management has shifted the biodiversity loss curve for tunas and billfishes, whereas the curve continues to worsen for sharks, which are highly undermanaged. While populations of highly valuable commercial species are being rebuilt, the next management challenge is to halt and reverse the harm afflicted by these same fisheries to broad oceanic biodiversity.
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