A new interstellar polyatomic molecule: detection of propynal in the cold cloud TMC-1

We report the detection of the acetylene derivative propynal (HC triple bond CCHO) in the cold cloud TMC-1, with an abundance that is very close to that for the related species tricarbon monoxide (C3O). Propadienone, an isomer of propynal with the formula H2C=C=C=O, was not detected and is hence less abundant than either C3O or HC2CHO.     

Ar-Ar chronology of the Martian meteorite ALH84001: evidence for the timing of the early bombardment of Mars

ALH84001, a cataclastic cumulate orthopyroxenite meteorite from Mars, has been dated by Ar-Ar stepped heating and laser probe methods. Both methods give ages close to 3,900 Ma. The age calculated is dependent on assumptions made about 39Ar recoil effects and on whether significant quantities of 40Ar from the Martian atmosphere are trapped in the meteorite. If, as suggested by xenon and nitrogen isotope studies, Martian atmospheric argon is present, then it must reside predominantly in the K-rich phase maskelynite. Independently determined 129Xe abundances in the maskelynite can be used to place limits on the concentration of the atmospheric 40Ar. These indicate a reduction of around 80 Ma to ages calculated on the assumption that no Martian atmosphere is present. After this correction, the nominal ages obtained are: 3940 +/- 50, 3870 +/- 80, and 3970 +/- 100 Ma. by stepped heating, and 3900 +/- 90 Ma by laser probe (1 sigma statistical errors), giving a weighted mean value of 3,920 Ma. Ambiguities in the interpretation of 39Ar recoil effects and in the contribution of Martian atmospheric 40Ar lead to uncertainties in the Ar-Ar age which are difficult to quantify, but we suggest that the true value lies somewhere between 4,050 and 3,800 Ma. This age probably dates a period of annealing of the meteorite subsequent to the shock event which gave it its cataclastic texture. The experiments provide the first evidence of an event occurring on Mars coincident with the time of the late heavy bombardment of the Moon and may reflect a similar period of bombardment in the Southern Highlands of Mars. Whether the age determined bears any relationship to the time of carbonate deposition in ALH84001 is not known. Such a link depends on whether the temperature associated with the metasomatic activity was sufficient to cause argon loss from the maskelynite and/or whether the metasomatism and metamorphism were linked in time through a common heat source.     

天然裂缝油藏水平井的产量预测和经济评价

本文提出了一种系统性的方法学,它综合了向井流入动态分析,产量预测和经济方面的知识。本文采用这种方法学优选用水平井技术开采天然裂缝油藏的最佳开采方式。在物质平衡分析和线性拟合油藏流体性质与油藏压力关系的基础上,提出了溶解气驱天然裂油藏中水平井的产能动态预测分析方法。天然裂缝特征对产能动态的影响用向井流入方程来解释。本文还介绍一种详细解释现金流时间价值的经济评价模型,该模型考虑到利率和通货膨胀的影响,     

Hard Burst Emission from the Soft Gamma Repeater SGR 1900+14

We present evidence for burst emission from SGR 1900+14 with a power-law high-energy spectrum extending beyond 500 keV. Unlike previous detections of high-energy photons during bursts from soft gamma repeaters (SGRs), these emissions are not associated with extraordinarily bright flares. Not only is the emission hard, but the spectra are better fitted by D. Band's gamma-ray burst (GRB) function rather than by the traditional optically thin thermal bremsstrahlung model. We find that the spectral evolution within these hard events obeys a hardness/intensity anticorrelation. Temporally, these events are distinct from typical SGR burst emissions in that they are longer ( approximately 1 s) and have relatively smooth profiles. Despite a difference in peak luminosity of greater, similar1011 between these bursts from SGR 1900+14 and cosmological GRBs, there are striking temporal and spectral similarities between the two kinds of bursts, aside from spectral evolution. We outline an interpretation of these events in the context of the magnetar model.     

WMO和世界臭氧研究

ＷＭＯ和世界臭氧研究Ｄｒ．Ｒｕｍｅｎ；Ｄ．Ｂｏｊｋｏｖ１前言最近二十年来，臭氧研究已从仅是一小部分科学家感兴趣的大气痕量气体研究发展成一个全球紧迫性课题。这种变革的发生是因为这方面的科学家确信大气臭氧的通常含量由于人类活动而发生着变化。臭氧（Ｏ３）是...