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Hydrothermal (NN)-N-15-N-15 abundances constrain the origins of mantle nitrogen 期刊论文
NATURE, 2020, 580 (7803) : 367-+
作者:  Zhao, Steven;  Jang, Cholsoon;  Liu, Joyce;  Uehara, Kahealani;  Gilbert, Michael;  Izzo, Luke;  Zeng, Xianfeng;  Trefely, Sophie;  Fernandez, Sully;  Carrer, Alessandro;  Miller, Katelyn D.;  Schug, Zachary T.;  Snyder, Nathaniel W.;  Gade, Terence P.;  Titchenell, Paul M.;  Rabinowitz, Joshua D.;  Wellen, Kathryn E.
收藏  |  浏览/下载：14/0  |  提交时间：2020/05/13

Nitrogen is the main constituent of the Earth'  s atmosphere, but its provenance in the Earth'  s mantle remains uncertain. The relative contribution of primordial nitrogen inherited during the Earth'  s accretion versus that subducted from the Earth'  s surface is unclear(1-6). Here we show that the mantle may have retained remnants of such primordial nitrogen. We use the rare (NN)-N-15-N-15 isotopologue of N-2 as a new tracer of air contamination in volcanic gas effusions. By constraining air contamination in gases from Iceland, Eifel (Germany) and Yellowstone (USA), we derive estimates of mantle delta N-15 (the fractional difference in N-15/N-14 from air), N-2/Ar-36 and N-2/He-3. Our results show that negative delta N-15 values observed in gases, previously regarded as indicating a mantle origin for nitrogen(7-10), in fact represent dominantly air-derived N-2 that experienced N-15/N-14 fractionation in hydrothermal systems. Using two-component mixing models to correct for this effect, the (NN)-N-15-N-15 data allow extrapolations that characterize mantle endmember delta N-15, N-2/Ar-36 and N-2/He-3 values. We show that the Eifel region has slightly increased delta N-15 and N-2/Ar-36 values relative to estimates for the convective mantle provided by mid-ocean-ridge basalts(11), consistent with subducted nitrogen being added to the mantle source. In contrast, we find that whereas the Yellowstone plume has delta N-15 values substantially greater than that of the convective mantle, resembling surface components(12-15), its N-2/Ar-36 and N-2/He-3 ratios are indistinguishable from those of the convective mantle. This observation raises the possibility that the plume hosts a primordial component. We provide a test of the subduction hypothesis with a two-box model, describing the evolution of mantle and surface nitrogen through geological time. We show that the effect of subduction on the deep nitrogen cycle may be less important than has been suggested by previous investigations. We propose instead that high mid-ocean-ridge basalt and plume delta N-15 values may both be dominantly primordial features.


  
A glimpse inside delta Scuti stars 期刊论文
NATURE, 2020, 581 (7807) : 141-142
作者:  Green, Douglas R.
收藏  |  浏览/下载：4/0  |  提交时间：2020/07/03

Patterns in the vibrations of stars produce a sort of natural music that offers clues to the stars'  internal structure. Astronomers have identified such patterns for some delta Scuti stars, a group for which this music had been elusive.


The oscillation modes of an enigmatic group of stars.


  
Constraint on the matter-antimatter symmetry-violating phase in neutrino oscillations 期刊论文
NATURE, 2020, 580 (7803) : 339-+
作者:  Houben, Lothar;  Weissman, Haim;  Wolf, Sharon G.;  Rybtchinski, Boris
收藏  |  浏览/下载：16/0  |  提交时间：2020/07/03

The charge-conjugation and parity-reversal (CP) symmetry of fundamental particles is a symmetry between matter and antimatter. Violation of this CP symmetry was first observed in 1964(1), and CP violation in the weak interactions of quarks was soon established(2). Sakharov proposed(3) that CP violation is necessary to explain the observed imbalance of matter and antimatter abundance in the Universe. However, CP violation in quarks is too small to support this explanation. So far, CP violation has not been observed in non-quark elementary particle systems. It has been shown that CP violation in leptons could generate the matter-antimatter disparity through a process called leptogenesis(4). Leptonic mixing, which appears in the standard model'  s charged current interactions(5,6), provides a potential source of CP violation through a complex phase dCP, which is required by some theoretical models of leptogenesis(7-9). This CP violation can be measured in muon neutrino to electron neutrino oscillations and the corresponding antineutrino oscillations, which are experimentally accessible using accelerator-produced beams as established by the Tokai-to-Kamioka (T2K) and NOvA experiments(10,11). Until now, the value of dCP has not been substantially constrained by neutrino oscillation experiments. Here we report a measurement using long-baseline neutrino and antineutrino oscillations observed by the T2K experiment that shows a large increase in the neutrino oscillation probability, excluding values of dCP that result in a large increase in the observed antineutrino oscillation probability at three standard deviations (3 sigma). The 3 sigma confidence interval for delta(CP), which is cyclic and repeats every 2p, is [-3.41, -0.03] for the so-called normal mass ordering and [-2.54, -0.32] for the inverted mass ordering. Our results indicate CP violation in leptons and our method enables sensitive searches for matter-antimatter asymmetry in neutrino oscillations using accelerator-produced neutrino beams. Future measurements with larger datasets will test whether leptonic CP violation is larger than the CP violation in quarks.


  
Giant thermal Hall conductivity in the pseudogap phase of cuprate superconductors 期刊论文
NATURE, 2019, 571 (7765) : 376-+
作者:  Grissonnanche, G.;  Legros, A.;  Badoux, S.;  Lefrancois, E.;  Zatko, V.;  Lizaire, M.;  Laliberte, F.;  Gourgout, A.;  Zhou, J. -S.;  Pyon, S.;  Takayama, T.;  Takagi, H.;  Ono, S.;  Doiron-Leyraud, N.;  Taillefer, L.
收藏  |  浏览/下载：8/0  |  提交时间：2019/11/27
Climatic control of Mississippi River flood hazard amplified by river engineering 期刊论文
NATURE, 2018, 556 (7699) : 95-+
作者:  Munoz, Samuel E.;  39;Donnell, Michelle
收藏  |  浏览/下载：4/0  |  提交时间：2019/11/27
Phosphatidylinositol 3-kinase delta blockade increases genomic instability in B cells 期刊论文
NATURE, 2017, 542 (7642) : 489-+
作者:  Compagno, Mara;  Wang, Qi;  Pighi, Chiara;  Cheong, Taek-Chin;  Meng, Fei-Long;  Poggio, Teresa;  Yeap, Leng-Siew;  Karaca, Elif;  Blasco, Rafael B.;  Langellotto, Fernanda;  Ambrogio, Chiara;  Voena, Claudia;  Wiestner, Adrian;  Kasar, Siddha N.;  Brown, Jennifer R. .;  Sun, Jing;  Wu, Catherine J.;  Gostissa, Monica;  Alt, Frederick W.;  Chiarle, Roberto
收藏  |  浏览/下载：4/0  |  提交时间：2019/04/09