The influence of the inter-decadal Pacific oscillation on US precipitation during 1923–2010

Precipitation over the contiguous United States exhibits large multi-decadal oscillations since the early twentieth century, and they often lead to dry (e.g., 1946–1976 and 1999-present) and wet (e.g., 1977–1998) periods and apparent precipitation trends (e.g., from the 1950s to 1990s) over most of the western and central US. The exact cause of these inter-decadal variations is not fully understood. Using observational and reanalysis data and model simulations, this paper examines the influence of the Inter-decadal Pacific Oscillation (IPO) on US precipitation. The IPO is a leading mode of sea surface temperatures (SSTs) seen mostly in the Pacific Ocean. It is found that decadal precipitation variations over much of the West and Central US, especially the Southwest, closely follow the evolution of the IPO (r = 0.85 during 1923–2010 for the Southwest US), and the dry and wet periods are associated, respectively, with the cold and warm phases of the IPO. In particular, the apparent upward trend from the 1950s–1990s and the dry decade thereafter in precipitation over much of the West and Central US are largely caused by the IPO cycles, which switched to a warm phase around 1977 and back to a cold phase around 1999. An atmospheric model forced with observed SSTs reproduces much of this association of US precipitation with the IPO (r = 0.95 between smoothed observed and simulated Southwest US precipitation during 1950–2009 and r = 0.88 between the simulated Southwest US precipitation and the IPO). Atmospheric reanalysis and model data both show a strong high (low) pressure center and anti-cyclonic (cyclonic) anomaly circulation over the North Pacific in the lower troposphere during cold (warm) phases of the IPO, which lead to dry and cold northwesterly and northerly winds and below-normal precipitation over much of the West US during IPO cold periods. The IPO induced changes are most pronounced during the boreal cold season. The results reinforce the notion that tropical Pacific SSTs (and the accompanying SST anomalies in the North Pacific) have large impacts on US precipitation and highlight the need to understand and simulate the IPO for decadal prediction of US precipitation.     

Tail Emission from a Ring-like Jet: Its Application to Shallow Decays of Early Afterglows and GRB 050709

Similar to the case of pulsars the magnetic axis and the spin axis of gamma-ray burst sources may not lie on the same line. This may cause the formation of a ring-like jet due to collimation of the processing magnetic axis. We analyze the tail emission from such a jet, and find that it has a shallow decay phase with a temporal index of -1/2 if the Lorentz factor of the ejecta is not very high, which is consistent with the shallow decay phase of some early X-ray afterglow detected by Swift. The ring-like jet has a tail cusp with sharp rising and very sharp decay. This effect can provide an explanation for the re-brightening and sharp decay of the X-ray afterglow of GRB 050709.     

The Large-Scale, Decelerating X-ray Jets from the Microquasar Xte J1550−564: Evidence for External Shocks Caused by the Jet-Ism Interaction?

Large-scale, decelerating, relativistic X-ray jets from microquasar XTE J1550−564 has been recently discovered with Chandra by Corbel et al. (2002). We find that the dynamical evolution of the approaching jet at the late time is consistent with the well-known Sedov evolutionary phase R∝ t ^2/5. A trans-relativistic external shock dynamic model by analogy with the evolution of gamma-ray burst remnants, is shown to be able to fit the proper-motion data of the approaching jet reasonably well. The inferred interstellar medium density around the source is well below the canonical value n _ISM∼1 cm⁻³. The rapidly fading X-ray emission can be interpreted as synchrotron radiation from the non-thermal electrons in the adiabatically expanding ejecta. These electrons were accelerated by the reverse shock (moving back into the ejecta) which becomes important when the inertia of the swept external matter leads to an appreciable slowing down of the original ejecta.     

广义相对论效应对脉冲星γ射线辐射的影响

本文研究了广义相对论效应和量子力学效应对中子量γ射线辐射的影响．通过选择磁偶极矩以及观察者视线与磁轴之间的夹角这两个观测量作为参量，我们数值计算了从中子星表面发射的、传播方向沿着磁场的光子的逃逸能量．我们得到，在磁偶极矩较小时，量子力学效应不重要，而广义相对论效应使逃逸能量显著降低；当磁偶极矩很大时，两个效应几乎相抵消，光子的逃逸能量几乎不受它们的影响．我们讨论这些结果在脉冲星γ射线谱上的意义．     

Estimates of AGN Black Hole Mass and Minimum Variability Timescale

Black hole mass is one of the fundamental physical parameters of active galactic nuclei (AGNs), for which many methods of estimation have been proposed. One set of methods assumes that the broad-line region (BLR) is gravitationally bound by the central black hole potential, so the black hole mass can be estimated from the orbital radius and the Doppler velocity. Another set of methods assumes the observed variability timescale is determined by the orbital timescale near the innermost stable orbit around the Schwarzschild black hole or the Kerr black hole, or by the characteristic timescale of the accretion disk. We collect a sample of 21 AGNs, for which the minimum variability timescales have been obtained and their black hole masses (Mσ) have been well estimated from the stellar velocity dispersion or the BLR size-luminosity relation. Using the minimum variability timescales we estimated the black hole masses for 21 objects by the three different methods, the results are denoted by Ms, Mk and Md, respectively. We compared each of them with Mσindividually and found that: (1) using the minimum variability timescale with the Kerr black hole theory leads to small differences between Mσand Mk, none exceeding one order of magnitude, and the mean difference between them is about 0.53 dex; (2) using the minimum variability timescale with the Schwarzschild black hole theory leads to somewhat larger difference between Mσand Ms: larger than one order of magnitude for 6 of the 21 sources, and the mean difference is 0.74 dex; (3) using the minimum variability timescale with the accretion disk theory leads to much larger differences between Mσand Md, for 13 of the 21 sources the differences are larger than two orders of magnitude; and the mean difference is as high as about 2.01 dex.     

天鹅座X-1硬X射线的能量谱

1985年9月22日,我们用空间硬X射线望远镜HAPI-2,在我国的高空气球上,对天鹅座X-1进行了观测,望远镜几何面积为140cm~2,观测能区20—200keV,空间定向精度±0.2°。获得的硬X射线能谱陡,总辐射能流LX～1.0×1~(37)erg/sec,低于常规态。本文将介绍望远镜的性能和观测过程,能谱分析的结果,并对当时天鹅座X-1可能的“态”进行讨论。     

Research on protection of steel piles of Baoshan general steel factory wharf by using DZ and DZ-2 tapes

Steel piles at the tidal zone can be seriously corroded. Common protective methods such as painting or coating with rubber or other protective materials, etc. cannot provide full protection when used as supplementary protection because these traditional methods require strict pretreatment and sealing of the metallic surface from the corrosive mediums, and time for the protective coatings to solidify. This is very difficult under the severe action of waves and surges on the sea. With our oil-soluble DZ-2 tape, protection efficiency for hanging steel plates at the tidal and splash zones reaches to 82–99%. The protection efficiency of water soluble DZ tape at the tidal zone reaches to 92.9%. The DZ and DZ-2 tapes can rapidly reduce the original corrosion velocity to ten percent and one percent respectively as fully proved by the 500 hour rapid corrosion testing with indoor salt fog and by the relevant electrochemical parameters of instantaneous corrosion velocity, etc. DZ tape absorbs much OH⁻ to cause a pH rise. A synergistic protective effect is gained when DZ tape is used together with cathodic protection of steel piles at the tidal zone. The working principle of DZ tape is different from that of DZ-2 tape even though they are composed of the same chemical materials. The latter provides protection because of the close affinity between metal and its carboxyl group shields the active centre at the metal surface to reduce the activation energy of metal. The carbon chain forms a covering oil film of netted structure. Dai Tao, Dai Wei and Xia Caiyuan et al. participated in the research and made useful contribution. Contribution No. 1656 from the Institute of Oceanology, Academia Sinica.     

河南省富碱侵入岩与金矿床关系浅析

河南省华北陆块南缘富碱侵入岩与金矿床成矿关系主要表现在空间、热动力和衍生关系三方面，与碱性岩有关的金矿床主要分为三种类型：热液－淋滤富集型、含金剪切带型和熔结（爆发）角砾岩型。富碱岩石含金背景值总体较高，近矿围岩含金丰度低于远矿围岩，富碱侵入体中的部分金组分参与了成金作用。区域侵入体含金性，其一：沿着栾川—方城深大断裂带分布的富碱浅成侵入体的成矿作用主要表现为区域构造活动引发淋滤富集作用和含金剪切构造带成金作用；其二：位于成金基底源区出露的一些富碱侵入体的成矿作用主要表现为爆发角砾岩和热液蚀变。     

Toxic effects of Zn2+, Cu2+, Cd2+ and NH3 on Chinese prawn

This study deals with the toxic effects of Zn²⁺, Cu²⁺, Cd²⁺ and NH₃ on Chinese prawn (Penaeus orientalis). The median lethal concentrations of the toxic matters on Chinese prawn were determined. Cd²⁺>Cu²⁺>Zn²⁺>NH₃-Nm is the toxic order of these chemicals to Chinese prawn. The toxic order of concentrated Zn²⁺ and Cd²⁺ in tissues and organs of Chinese prawn is in the order. gill>shell+appendage>viscera>muscle.     

甘南毕家山铅锌矿床地质特征与成因

该矿床由两种类型矿化组成:(1)与所谓“微石英岩”密切共生的成层碎屑矿;(2)层状矿下伏石灰岩顶部的网脉矿。矿石硫化物在同位素组成上与围岩中的黄铁矿显然不同,其δ~(34)S值( 15至 18)表明可能是海水来源的,由海水硫酸离子在较高温度下无机还原而成。矿石中的碳酸盐矿物以较低的δ~(13)C和较高的δ~(18)O值不同于围岩石灰岩,前者表明可能有深成碳参加,后者表明成矿流体可能在较高温度下与硅酸盐岩石达到了同位素平衡。氧化硅的δ~(18)O值很重,落入海相燧石的变化范围。区域内没有火山活动的确切证据,以海水来源为主的成矿流体可能是沿分开不同地层小区的区域性断裂循环并被加热的。