Archaeal acylamino acid releasing enzyme/lipase:Crystallization and preliminary crystallographic analysis in a new crystal form

A primitive orthorhombic crystal form of acylamino acid releasing enzyme‘lipase(APE1547)from hyperthermophilic archaeon Aeropyrum pernix strain K1 has been obtained at 291K.The diffraction pattern of the crystal extends to 0.27nm resolution at 100K using Cu Kαradiation.The crystal belongs to the space group P212121 with unit cell dimensions of b=6.399,b=10.439and c=16.953nm.The presence of two molecules per asymmetric unit gives a crystal volume per protein mass(Vm)of 0.0022nm^3 Da^-1 and a solvent content of 43% by volume.A full set of X-ray diffraction data were collected to 0.3nm from the native crystal.     

Quaternary high-resolution opal record and its paleoproductivity implication at ODP Site 1143,southern South China Sea

The correlation of opal content and MAR with oxygen isotopic records of benthonic foraminifera at Site 1143, southern South China Sea indicates that,since about 900 ka,the increasing opal content and MAR during the interglacial periods is inferred to reflect the bigher surface productivity ,for the intensified summer monsoon during the interglacial periods would result in the enhanced upwelling and nutrient supply,Time-sequence spectral analyses of oxygen isotopic record ,opal content and MAR at intervals of 0-900 ka reveal that the changes of surface productivity were dominantly forced by the variations of the earth orbital cycles.     

A new Euprox from the Late Miocene of Yuanmou,Yunnan Province,China,with interpretation of its paleoenvironment

The Yuanmou Basin of Yunnan Province is a hotspot for the research of early homind evolution and its environmental background.During the implementation of the Program“Research of the Origin and Evolution of Early Man and Its Environmental Baqckground” from 1998 to 2001,a huge quantity of hominoid and mammal fossils were collected.The present report systematically describes an Euprox robustus sp.nov.identified during the recent laboratory work on the collected material.Euprox is a group of earliest cervids with true antlers.The new species is the third one of the genus discovered in China.Judged by its morphologic characteristics,the new species feed on juicy and tender leaves of dicotyledon.It implies that the vegetation of its epoch in the Yuanmou Basin is a kind of southern subtropical evergreen forest and the climate is humid and temperate with evident seasonality.The latter is mostly influenced by the monsoon and secondly by the latitude.     

Inorganic chemical composition and source signature of PM2.5 in Beijing during ACE-Asia period

Aerosol samples for PM2.5 were collected in Beijing for 38 consecutive days from March to April 2001 using an IMPROVE Sampler. Concentrations of 20 elements in PM2.5 were determined using a PIXE method. Results show that the average mineral dust concentration of PM2.5 was 14.6 Ilg/m3 during the observation period. On the sand-dust event days of March 21 and April 10, dust PM2.5 mass concentrations were 62.4 and 54.1 μg/m^3, respectively.These demonstrate that fine particle pollution by dust event in Beijing was very severe. The enrichment factors of S and Cu reached minimums on the dusty days and were high on the non-dusty days. It is considered that enrichment factors of elements in PM2.5, which are associated with human activities, can probably provide an effective method to distinguish local sources from external sources of dust. Factor analysis on the chemical composition in PM2.5 shows that sources of crustal matters, anthropogenic emission, and oil combustion contributed to PM2.5 levels in air in the springtime of 2001 in Beijing.     

Lorenz系统混沌解序列可预报性的统计检验

利用Lorenz简化热对流模式产生了吸引子区域内的混沌解序列，对截取的序列进行了乎稳性和正态性检验．按照3种情形分别选取样本，并应用统计预报中的ARMA模型、多元线性回归模型、多项式回归模型和均值生成函数模型等作出项报。比较分析表明：所选取方程组产生的混池解序列，呈现非周期、非乎稳、非正态特性等极不规则的分布，导致几种统计模型对于两个不稳定平衡状态间的不确定的突变情形基本失去了预报能力，系统行为几乎无法预测，其根本原因在于系统的混沌特性。但在某一不稳定平衡状态内，序列段呈现振幅不断放大的准周期振荡，具有一定的规律性，几种统计模型预报的效果较好，说明在应用统计方法进行预报的前提下，系统行为存在着局部时段的有限的可预报性。     

中国西部绿化对东亚季风气候影响的数值模拟

中国西部大开发战略中的生态环境建设将在西部地区引起显著的地表覆盖变化。根据最新的全球地表特征数据库资料和21世纪初中国西部生态环境三大重点建设工程的具体规划，得出两种植被，即现实植被和虚拟植被。并利用RIEMS—TEA模式，通过一次敏感性试验，发现西部地区绿化明显影响东亚的季风系统和中国东部季风区气候。模拟试验显示，中国西部绿化会明显增强东亚夏季风，这将会加强中国东部由南向北的水汽输送，并有利于输送邻近海洋的水汽到大陆，使得中国大陆东部季风区整体出现降温、增湿和降水增加。而且，温度、湿度、气压和风速受影响的程度在垂直方向上都已超出了边界层之外。     

地震离我们有多近？——访中国地震局张少泉研究员

最近，地震频频，一两个月内，相继发生了阿尔及利亚地震、日本地震、中国台湾地震、内蒙古地震、新疆伽师地震等等。这些地震，时间相隔短，比较密集。一时间，人们有些担心：目前，地震活动是否进入了频繁期?中国地震研究的最新进展如何?我们就这些问题，采访了中国地震局的张少泉研究员。     

Temperature variations on the Tibetan Plateau over the last two millennia

The paleoclimate data recovered from ice cores,tree rings and lake sediments indicate regional features of cfimatic change on the Tibeta n Plateau (TP) during the last 2000 years. The composite temperature reconstructions in-dicate that several main climatic episodes, such as the “LittleIce Age“ between 1400 and 1900, the “Medieval Warm Pe-riod“ in 1150-1400, a less warm period in 800-1100, and an earlier cold period between the 3rd and 5th centuries,occurred in the TP. In addition, temperature varied from region to region. The period from AD 800 to 1100, which waswarm in northeastern TP, was contemporaneous with cool-ing in the western and southern TP. The southern TP ex-perienced warming between 1150 and 1400. For western TP,the δ^18O records of the Guliya ice core indicate that the pe-Hod 1250-1500 witnessed a clear warming. Large-scaletrends in the temperature history from northeastern TP aremore similar to those in eastern China than are the trendsfrom the Guliya ice cap far to the west and southern TP. The most prominent similarities between the temperature varia-tions of the TP and eastern China are such cold phases as 1100-1150, 1500-1550, 1650-1700 and 1800-1850, andthe latter three cold events match with three widespreadg lacial advances which occurred on the TP during the Little Ice A2e.     

山东省春季旱年与涝年对应的大气环流

利用美国国家环境预报中心与美国国家大气研究中心(NCEP／NCAR)再分析资料及山东省1961—1998年16个代表站的3～5月降水实测资料，对山东春季旱年与涝年进行划分并对其对应的大气环流形势进行了分析。结果表明，山东春季涝年与旱年的大气环流形势存在明显的差异，东亚大槽的异常减弱、乌拉尔地区高度场的明显降低是造成山东春季降水异常偏多的主要原因；孟加拉湾的水汽输送是山东地区春季降水的重要水汽条件。