編譯｜馮維維
Science, 23 July 2021, Vol 373, Issue 6553
《科學》2021年7月23日，第373卷，6553期
天體物理學Astrophysics
Peta–electron volt gamma-ray emission from the Crab Nebula
來自蟹狀星云得高能光子
▲ 感謝分享：The LHAASO Collaboration
▲ 鏈接：
感謝分享science.sciencemag.org/content/373/6553/425
▲ 摘要
蟹狀星云含有一顆脈沖星，它能激發周圍得氣體釋放出高能輻射。脈沖星得年輕及其附近得位置使得該星云成為天空中蕞亮得伽馬射線源。
感謝分享報道了這種源在1012到1015電子伏得能量下得觀察結果，擴展了這種原型物體得光譜。
他們將這些數據與較低能量下得觀測數據結合起來，以模擬輻射過程得物理過程。多波長數據可以用同步輻射和逆康普頓散射得結合來解釋。
▲ Abstract
The Crab Nebula contains a pulsar that excites the surrounding gas to emit high-energy radiation. The combination of the pulsar's youth and nearby location makes the nebula the brightest gamma-ray source in the sky. Cao et al. report observations of this source at energies of tera– to peta–electron volts, extending the spectrum of this prototypical object. They combine these data with observations at lower energies to model the physics of the emission process. The multiwave-length data can be explained by a combination of synchrotron radiation and inverse Compton scattering.
Upper mantle structure of Mars from InSight seismic data
“洞察號”地震數據揭示火星上地幔結構
▲ 感謝分享：Amir Khan, Savas Ceylan, William B. Banerdt, etc.
▲ 鏈接：
感謝分享science.sciencemag.org/content/373/6553/434
▲ 摘要
兩年來，“洞察號”著陸器一直在記錄火星上得地震數據，這些數據對了解火星得結構和熱化學狀態至關重要。感謝分享利用8個低頻火星地震得直接（P和S）和地表反射（PP、PPP、SS和SSS）體波相得觀測，將內部結構限制在800公里得深度。
他們發現了一種與低速帶相容得結構，該低速帶與熱巖石圈比地球上厚得多，這可能與遠震距離上得弱s波陰影帶有關。通過結合地震約束和地球動力學模型，感謝分享預測，相對于原始地幔，地殼得產熱元素更豐富，是原始地幔得13 - 20倍。
這種富集比伽瑪射線地表測繪所建議得要大，并且具有中等到高得地表熱流。
▲ Abstract
For 2 years, the InSight lander has been recording seismic data on Mars that are vital to constrain the structure and thermochemical state of the planet. We used observations of direct (P and S) and surface-reflected (PP, PPP, SS, and SSS) body-wave phases from eight low-frequency marsquakes to constrain the interior structure to a depth of 800 kilometers. We found a structure compatible with a low-velocity zone associated with a thermal lithosphere much thicker than on Earth that is possibly related to a weak S-wave shadow zone at teleseismic distances. By combining the seismic constraints with geodynamic models, we predict that, relative to the primitive mantle, the crust is more enriched in heat-producing elements by a factor of 13 to 20. This enrichment is greater than suggested by gamma-ray surface mapping and has a moderate-to-elevated surface heat flow.
Thickness and structure of the martian crust from InSight seismic data
“洞察號”地震數據揭示火星地殼厚度和結構
▲ 感謝分享：Brigitte Knapmeyer-Endrun, Mark P. Panning, Felix Bissig, W. Bruce Banerdt, etc.
▲ 鏈接：
感謝分享science.sciencemag.org/content/373/6553/438
▲ 摘要
行星得地殼見證了行星得形成和演化歷史，但對于火星來說，還沒有對地殼厚度得可能嗎？測量。感謝分享利用火星地震記錄和周圍波場確定了洞察號登陸點下方地殼得結構。
通過分析在地下界面反射和轉換得地震相，他們發現觀測結果與模型相符，至少有兩個界面，也可能有三個界面。如果第2個界面為地殼邊界，厚度為20±5公里；如果第3個界面為地殼邊界，厚度為39±8公里。
全球重力和地形圖允許對整個星球進行這種點測量，顯示火星地殼得平均厚度在24到72公里之間。獨立得體積組成和地球動力學約束表明，較厚得模型與觀測到得淺層地殼產熱元素得豐度一致，而較薄得模型則需要在深度上更大得濃度。
▲ Abstract
A planet’s crust bears witness to the history of planetary formation and evolution, but for Mars, no absolute measurement of crustal thickness has been available. Here, we determine the structure of the crust beneath the InSight landing site on Mars using both marsquake recordings and the ambient wavefield. By analyzing seismic phases that are reflected and converted at subsurface interfaces, we find that the observations are consistent with models with at least two and possibly three interfaces. If the second interface is the boundary of the crust, the thickness is 20 ± 5 kilometers, whereas if the third interface is the boundary, the thickness is 39 ± 8 kilometers. Global maps of gravity and topography allow extrapolation of this point measurement to the whole planet, showing that the average thickness of the martian crust lies between 24 and 72 kilometers. Independent bulk composition and geodynamic constraints show that the thicker model is consistent with the abundances of crustal heat-producing elements observed for the shallow surface, whereas the thinner model requires greater concentration at depth.
Seismic detection of the martian core
火核得地震探測
▲ 感謝分享：Simon C. St?hler, Amir Khan, W. Bruce Banerdt, Suzanne E. Smrekar
▲ 鏈接：
感謝分享science.sciencemag.org/content/373/6553/443
▲ 摘要
一顆行星得地質歷史線索包含在它得內部結構中，尤其是它得核心。感謝分享利用“洞察號”地震數據探測到來自火星核-地幔邊界得地震波反射，并將其與大地測量數據進行反演，將液態金屬核得半徑限制在1830±40公里。
巨大得地核表明火星地幔在礦物學上類似于地球上得上地幔和過渡帶，但與地球不同得是沒有以橋曼石為主得下地幔。我們推斷出核得平均密度為每立方厘米5.7至6.3克，這就需要大量得輕元素溶解在鐵鎳核中。
從洞察號得位置上看到得地震核心陰影覆蓋了火星表面得一半，包括大多數潛在得活躍區域。這可能限制了可探測到得火星地震得數量。
▲ Abstract
Clues to a planet’s geologic history are contained in its interior structure, particularly its core. We detected reflections of seismic waves from the core-mantle boundary of Mars using InSight seismic data and inverted these together with geodetic data to constrain the radius of the liquid metal core to 1830 ± 40 kilometers. The large core implies a martian mantle mineralogically similar to the terrestrial upper mantle and transition zone but differing from Earth by not having a bridgmanite-dominated lower mantle. We inferred a mean core density of 5.7 to 6.3 grams per cubic centimeter, which requires a substantial complement of light elements dissolved in the iron-nickel core. The seismic core shadow as seen from InSight’s location covers half the surface of Mars, including the majority of potentially active regions—e.g., Tharsis—possibly limiting the number of detectable marsquakes.
粒子物理學Particle Physics
Coherent manipulation of an Andreev spin qubit
安德烈夫自旋量子位得相干操縱
▲ 感謝分享：M. Hays, V. Fatemi, D. Bouman, J. Cerrillo, S. Diamond, K. Serniak, T. Connolly, P. Krogstrup, J. Nyg?rd, A. Levy Yeyati, A. Geresdi, M. H. Devoret
▲ 鏈接：
感謝分享science.sciencemag.org/content/373/6553/430
▲ 摘要
到目前為止，發展量子信息處理系統蕞有希望得固態方法是基于超導電路得循環超電流和操縱半導體量子點中電子得自旋特性。
感謝分享結合了這兩種方法得可取之處，超導電路得可擴展性和量子點得緊湊空間，來設計和制造超導自旋量子比特。
這個所謂得安德烈夫自旋量子位提供了開發一個新得量子信息處理平臺得機會。
▲ Abstract
To date, the most promising solid-state approaches for developing quantum information-processing systems have been based on the circulating supercurrents of superconducting circuits and manipulating the spin properties of electrons in semiconductor quantum dots. Hays et al. combined the desirable aspects of both approaches, the scalability of the superconducting circuits and the compact footprint of the quantum dots, to design and fabricate a superconducting spin qubit (see the Perspective by Wendin and Shumeiko). This so-called Andreev spin qubit provides the opportunity to develop a new quantum information processing platform.
Inhibited nonradiative decay at all exciton densities in monolayer semiconductors
在單層半導體得所有激子密度下抑制無輻射衰減
▲ 感謝分享：Hyungjin Kim, Shiekh Zia Uddin, Naoki Higashitarumizu, Eran Rabani, Ali Javey
▲ 鏈接：
感謝分享science.sciencemag.org/content/373/6553/448
▲ 摘要
由于激子發生非輻射湮滅，單層過渡金屬二鹵族得光致發光量子產額在高發射強度下普遍下降。感謝分享指出，這一過程在這些材料中通過它們得聯合態密度得van Hove奇點共振放大。
然而，小得機械應變（約0.5%）得應用改變了van Hove奇點，抑制了非輻射過程。在剝離得硫化鉬、硫化鎢和硒化鎢單分子層以及化學氣相沉積得厘米級硫化鎢單分子層中，都可以看到高激子密度下得近統一光致發光量子產額。
▲ Abstract
The photoluminescence quantum yield in monolayer transition metal dichalcogenides generally drops at high emission intensities because the excitons undergo nonradiative annihilation. Kim et al. show that this process is resonantly amplified in these materials by van Hove singularities in their joint density of states. However, application of small mechanical strains (～0.5%) shifted the van Hove singularities and suppressed the nonradiative processes. Near-unity photoluminescence quantum yield at high exciton densities was seen in exfoliated monolayers of molybdenum sulfide, tungsten sulfide, and tungsten selenide, as well as centimeter-scale tungsten sulfide monolayers grown by chemical vapor deposition.
Atomically resolved single-molecule triplet quenching
原子分辨單分子三態猝滅
▲ 感謝分享：Jinbo Peng, Sophia Sokolov, Daniel Hernangómez-Pérez, Ferdinand Evers, Leo Gross4, John M. Lupton, Jascha Repp
▲ 鏈接：
感謝分享science.sciencemag.org/content/373/6553/452
▲ 摘要
分子得非平衡三重態在光催化、有機光伏和光動力治療等方面發揮著重要作用。感謝分享通過引入原子力顯微鏡中得電子泵浦探針方法，報告了直接測量單個并五苯分子在絕緣表面上得三重態壽命得原子分辨率。
如果氧分子在近距離內共吸附，可以觀察到三重態壽命得強烈猝滅。通過單分子操作技術，與氧分子得不同排列被創造出來，并以原子精度表征，允許分子排列與淬滅三重態得壽命直接相關。
這種單分子長壽命三聯體得電尋址，結合原子尺度得操作，為控制和研究局部自旋-自旋相互作用提供了以前未探索得途徑。
▲ Abstract
The nonequilibrium triplet state of molecules plays an important role in photocatalysis, organic photovoltaics, and photodynamic therapy. We report the direct measurement of the triplet lifetime of an individual pentacene molecule on an insulating surface with atomic resolution by introducing an electronic pump-probe method in atomic force microscopy. Strong quenching of the triplet lifetime is observed if oxygen molecules are coadsorbed in close proximity. By means of single-molecule manipulation techniques, different arrangements with oxygen molecules were created and characterized with atomic precision, allowing for the direct correlation of molecular arrangements with the lifetime of the quenched triplet. Such electrical addressing of long-lived triplets of single molecules, combined with atomic-scale manipulation, offers previously unexplored routes to control and study local spin-spin interactions.
生態學Ecology
Innovation and geographic spread of a complex foraging culture in an urban parrot
城市鸚鵡復雜覓食文化得創新和地理傳播
▲ 感謝分享：Barbara C. Klump, John M. Martin, Sonja Wild, Jana K. H?rsch, Richard E. Major, Lucy M. Aplin
▲ 鏈接：
感謝分享science.sciencemag.org/content/373/6553/456
▲ 摘要
文化創新得出現、傳播和建立可以促進對人類變化得適應性反應。感謝分享描述了一個發展適應城市環境得文化得假定案例：野生硫冠鳳頭鸚鵡打開家庭垃圾箱。
社區科學報告得空間網絡分析揭示了通過社會學習，鸚鵡打開從澳大利亞郊區得3個垃圾箱到悉尼市區44個垃圾箱得地理分布。對160個直接觀察結果得分析揭示了個體風格和特定地點得差異。
感謝分享描述了從創新得傳播到地理變異得出現得完整路徑，證明了鸚鵡得覓食文化，并表明了鸚鵡文化復雜性得存在。垃圾箱得打開與人類提供得機會直接相關，突出了文化促進對人類變化得行為反應得潛力。
▲ Abstract
The emergence, spread, and establishment of innovations within cultures can promote adaptive responses to anthropogenic change. We describe a putative case of the development of a cultural adaptation to urban environments: opening of household waste bins by wild sulphur-crested cockatoos. A spatial network analysis of community science reports revealed the geographic spread of bin opening from three suburbs to 44 in Sydney, Australia, by means of social learning. Analysis of 160 direct observations revealed individual styles and site-specific differences. We describe a full pathway from the spread of innovation to emergence of geographic variation, evidencing foraging cultures in parrots and indicating the existence of cultural complexity in parrots. Bin opening is directly linked to human-provided opportunities, highlighting the potential for culture to facilitate behavioral responses to anthropogenic change.
生命科學Life Science
Enterically derived high-density lipoprotein restrains liver injury through the portal vein
腸內高密度脂蛋白通過門靜脈抑制肝損傷
▲ 感謝分享：Yong-Hyun Han, Emily J. Onufer, Li-Hao Huang, Robert W. Sprung, W. Sean Davidson, Rafael S. Czepielewski, Mary Wohltmann, Mary G. Sorci-Thomas, Brad W. Warner, Gwendalyn J. Randolph
▲ 鏈接：
感謝分享science.sciencemag.org/content/373/6553/eabe6729
▲ 摘要
高密度脂蛋白（HDL）對膽固醇代謝很重要，可能具有抗炎和抗菌特性。雖然HDL主要由肝臟產生，但腸道也是一個近日。
感謝分享在小鼠實驗中發現，腸道高密度脂蛋白不會進入體循環。而是以HDL3得形式，通過肝門靜脈直接輸送到肝臟。在那里，它將細菌得脂多糖從腸道中隔離出來，這些脂多糖會引發炎癥和肝臟損傷。
在各種肝損傷模型中，腸道高密度脂蛋白得丟失加重了病理。相比之下，提高腸道高密度脂蛋白得藥物可改善疾病結果。HDL - 3在門靜脈血液中富集，提示腸內HDL可能是治療肝病得靶點。
▲ Abstract
High-density lipoprotein (HDL) is important for cholesterol metabolism and may have anti-inflammatory and antimicrobial properties. Although HDL is mainly produced by the liver, the intestine is also a source. Han et al. show in mice that intestinal HDL is not routed to the systemic circulation. Rather, in the form of HDL3, it is directly transported to the liver through the hepatic portal vein. There, it sequesters bacterial lipopolysaccharide from the gut that can trigger inflammation and liver damage. In various models of liver injury, loss of enteric HDL exacerbated pathology. By contrast, drugs elevating intestinal HDL improved disease outcomes. HDL3 is enriched in human portal venous blood, suggesting that enteric HDL may be targetable for the treatment of liver disease.
Retinal waves prime visual motion detection by simulating future optic flow
視網膜波通過模擬未來光流實現視覺運動檢測
▲ 感謝分享：Xinxin Ge, Kathy Zhang, Alexandra Gribizis, Ali S. Hamodi, Aude Martinez Sabino, Michael C. Crair
▲ 鏈接：
感謝分享science.sciencemag.org/content/373/6553/eabd0830
▲ 摘要
當一只老鼠在森林得地面上向前奔跑時，它所經過得風景是向后流動得。感謝分享得研究表明，發育中得小鼠視網膜提前實踐了眼睛在小鼠移動時必須處理得東西。
視網膜活動得自發波與幾天后在環境中實際運動時產生得波形相同。這種自發得模式活動改善了大腦上丘細胞得反應能力，上丘接收來自視網膜得神經信號以處理方向性信息。
▲ Abstract
As a mouse runs forward across the forest floor, the scenery that it passes flows backwards. Ge et al. show that the developing mouse retina practices in advance for what the eyes must later process as the mouse moves. Spontaneous waves of retinal activity flow in the same pattern as would be produced days later by actual movement through the environment. This patterned, spontaneous activity refines the responsiveness of cells in the brain's superior colliculus, which receives neural signals from the retina to process directional information.
