The 2dF Galaxy Redshift Survey: the dependence of galaxy clustering on luminosity and spectral type

We investigate the dependence of galaxy clustering on luminosity and spectral type using the 2dF Galaxy Redshift Survey (2dFGRS). Spectral types are assigned using the principal-component analysis of Madgwick et al. We divide the sample into two broad spectral classes: galaxies with strong emission lines ('late types') and more quiescent galaxies ('early types'). We measure the clustering in real space, free from any distortion of the clustering pattern owing to peculiar velocities, for a series of volume-limited samples. The projected correlation functions of both spectral types are well described by a power law for transverse separations in the range  2<( σ / h ^-1 Mpc)<15  , with a marginally steeper slope for early types than late types. Both early and late types have approximately the same dependence of clustering strength on luminosity, with the clustering amplitude increasing by a factor of ∼2.5 between L * and 4 L *. At all luminosities, however, the correlation function amplitude for the early types is ∼50 per cent higher than that of the late types. These results support the view that luminosity, and not type, is the dominant factor in determining how the clustering strength of the whole galaxy population varies with luminosity.     

距今五千年左右环境恶化事件对我国新石器文化的影响及其原因的初步探讨

距今五千年左右全球普遍存在一次变化幅度较大的突发性环境恶化事件 ,此事件导致各地生态环境发生了较大的变化 ,与此同时的我国新石器文化表现为衰退和在某些地点的中断。气候环境变化是该时段影响人类文化发展变化的主要因素。环境变化对史前文化影响的可能原因是 :气候变化导致生态环境变化 ,生态环境变化导致直接影响人类生存的生物营养源的变化 ,进而导致史前文化的变化。     

青海盐湖锂资源开发现状及对提锂产业发展建议

中国正处在环境污染治理和产业结构调整的关键时期,发展新能源产业是应对能源和环境危机的必然选择;同时,锂资源储备和提锂技术直接影响到国家能源战略安全。中国科学院青海盐湖所经过二十年开发,目前已形成一套成熟的选择性离子迁移分离提锂技术,并经过了产业化和工业应用验证,核心技术达到国际领先水平。该产业化具有绿色、高效、低能耗、低物耗、低产品成本、高纯度等特点,技术通用性好,可推广应用到青海、西藏高海拔生态脆弱地区以及南美玻利维亚、阿根廷、智利等高镁锂比盐湖中锂的分离提取,在高钙镁地热水、油(气)田水提锂方面也有一定的应用潜力。     

民勤盆地水资源可持续利用对策——2000年民勤水资源利用调查

水资源短缺和生态环境恶化已成为民勤绿洲面临的严重问题。本文在分析民勤盆地水资源特点及开发利用中存在的问题的基础上,本着水资源可持续利用的原则,从加强水资源保护与管理,发展节水农业生产体系,以及开源调水和减少人口等方面,提出了水资源可持续利用途径与措施。     

On the application of the coupled finite-infinite element method to geodetic boundary-value problem

Our aim is to introduce the Coupled Finite-Infinite Element Method (CFIEM) as a new alternative approach to the Earth’s gravity field modelling. We show that if the computational domain is large enough in radial direction, one can obtain the qualitatively and quantitatively comparable solution to the solution by the Finite Element Method (FEM). We study the influence of the size of the computational domain on the final CFIEM solution as well as the successive refinement of the discretization and its convergence to the exact solution. As an input data we use the synthetic boundary conditions computed from a Synthetic Earth Gravity Model (SEGM) and we test the CFIEM solution by the data generated directly from SEGM and the solution by the FEM.