Wave excitation in three-dimensional discs by external potential

We study the excitation of density and bending waves and the associated angular momentum transfer in gaseous discs with finite thickness by a rotating external potential. The disc is assumed to be isothermal in the vertical direction and has no self-gravity. The disc perturbations are decomposed into different modes, each characterized by the azimuthal index m and the vertical index n , which specifies the nodal number of the density perturbation along the disc normal direction. The   n = 0  modes correspond to the two-dimensional density waves previously studied by Goldreich & Tremaine and others. In a three-dimensional disc, waves can be excited at both Lindblad resonances (LRs; for modes with   n = 0, 1, 2, …  ) and vertical resonances (VRs; for the   n ≥ 1  modes only). The torque on the disc is positive for waves excited at outer Lindblad/vertical resonances and negative at inner Lindblad/vertical resonances. While the   n = 0  modes are evanescent around corotation, the   n ≥ 1  modes can propagate into the corotation region where they are damped and deposit their angular momenta. We have derived analytical expressions for the amplitudes of different wave modes excited at LRs and/or VRs and the resulting torques on the disc. It is found that for   n ≥ 1  , angular momentum transfer through VRs is much more efficient than LRs. This implies that in some situations (e.g. a circumstellar disc perturbed by a planet in an inclined orbit), VRs may be an important channel of angular momentum transfer between the disc and the external potential. We have also derived new formulae for the angular momentum deposition at corotation and studied wave excitations at disc boundaries.     

A Comparative Study of Genetic Variation betwccn Chinese Mitten Crab Eriocheir Sinensis and Hepu Mitten Crab E. Hepuensis

Horizontal starch gel electrophoresis was used to investigate the biochemical genetic structure of Chinese mittencrab Eriocheir sinensis and Hepu mitten crab E. hepuensis. Sixteen putative enzyme-coding loci were examined for forty-nineChinese mitten crabs and thirty-eight Hepu mitten crabs. Nine loci, AAT-1 *, AAT-2 *, G3PDH*, GPI*, IDHP-1 *, IDHP-2 *,MDH-1 *, MDH-2 * and PGM * , are polymorphic in Chinese mitten crab, and seven, AAT-1 *, AAT-2 *, GPI *, IDHP-1 *,MDH-1 *, MDH-2 * and PGM * , are polymorphic in Hepu mitten crab. The proportion of polymorphic loci and the expectedheterozygosity are 0.562 5 and 0.080 3 for Chinese mitten crab, and 0.437 5 and 0.075 4 for Hepu mitten crab. The Nei' s ge-netic distance between two species is 0.002 4.     

The effects of temperature and substrate on ontogenetic behavior of bastard halibut, Paralichthys olivaceus (T. et S.)

1 INTRODUCTION Scientific management of aquacultural andnatural populations studies on the early life historyof flatfishes in the aspects of their metamorphosisand benthic settlement accompanying pronouncedtransitions in morphology, behavior and habitatecology have received much attention (Youson,1988). Accumulated data showed that temperatureand substrate played a main role in the recruitmentsuccess of flatfish during their early development(Rijnsdorp et al., 1995, Gibson and Robb, 2000…     

VLBI软件相关处理机系统中的数据预处理方法

在绕月探测工程VLBI数据处理中心的软件相关处理机系统中，各VLBI观测站采集的原始数据必须经过预处理才能进行相关处理与条纹搜索等运算。处理机预处理模块对来自各个观测站的MARK5观测数据进行模式判别、寻找同步头、计算CRC校验码、时间同步等操作，生成时间长度为1min的标准Linux文件，并存放于硬盘阵列上，供相关处理和条纹搜索使用。预处理模块和软件相关处理模块、条纹搜索模块协调配合，保证了软件相关处理机系统在准实时和事后两种观测模式下的性能指标。     

The very low-frequency oscillation in tropical Pacific

The very low-frequency oscillation (VLFO) on interannual scale in the tropical Pacific is studied by analyzing the main components of the sea surface temperature, sea level pressure, cloudiness, humidity and the equivalent potential temperature over the tropical ocean surface. The nature of two components of VLFO and its propagation features are discussed from the view of air-sea interaction.     

Simultaneous solutions for photometric and spectroscopic observations of TX UMa

B andV light curves for one epoch and radial velocity curves of three different epochs have been analyzed to revise the solution of TX UMa. The solution has been adjusted simultaneously in the light curves and radial velocity curves by the method of Wilson and Devinney's differential correction. The primary star's surface rotation rate to synchronous rate is determined as 1.768 from one of the radial velocity curves. The absolute dimension of the system has been deduced based on the simultaneous solution. The primary star is well fitted to the evolutionary track for a single star while the secondary star, while filling its Roche lobe, is fitted to the evolutionary track for a close binary system.     

A STUDY ON REGIONAL DIFFERENCE OF CHINA＇S PAID URBAN LANDUSE SYSTEM AND GRADING

董黎明，李向明，冯长春ＡＳＴＵＤＹＯＮＲＥＧＩＯＮＡＬＤＩＦＦＥＲＥＮＣＥＯＦＣＨＩＮＡ＇ＳＰＡＩＤＵＲＢＡＮＬＡＮＤＵＳＥＳＹＳＴＥＭＡＮＤＧＲＡＤＩＮＧ￥ＤｏｎｇＬｉｍｉｎｇ；ＬｉＸｉａｎｇｍｉｎｇ；ＦｅｎｇＣｈａｎｇｃｈｕｎ（ＰｅｋｉｎｇＵｎｉ...     

用CSR4.0+CS模型计算海潮负荷改正

介绍了CSR3．0与CSR4．0 CS海潮模型，并对两模型进行了分析和实算比较，认为CSR4．0 CS比CSR3．0海潮模型精度更高，在计算中国测站海潮改正时，顾及中国近海海潮图是必要的。对我国第二期水准路线用CSR4．0 CS模型计算了海潮负荷改正，结果表明：海潮负荷对高精度水准测量的影响，主要取决于水准路线的近海位置，越是近海地区越明显；在近海区域，这项改正不能忽略。     

双Packer系统在鄂尔多斯盆地地下水勘查中的应用

双Packer系统在鄂尔多斯盆地地下水勘查中的应用,为在该盆地开展深层地下水水化学同位素的研究,提供了一个有效的工具。了解该系统的工作原理、应用条件和在鄂尔多斯盆地地下水勘查中的具体应用,对在我国水文界普及该技术具有重要意义。     

THE RESEARCH ON THE DISTRIBUTION AND FORMS OF HEAVY METALS IN THE XIANGJIANG RIVER SEDIMENTS

In this paper, the contents and various forms of Cd, Cu, Zn and Pb in the sediments of the Xiangjiang River have been investigated. The presentation of this paper focuses on the various forms and characteristics of the heavy metals in the column sediments at Xiawan Port of Zhuzhou, which has been severely polluted by a metallurgical plant.The forms of the heavy metals discussed in this paper are: The concentration of the exchangeable forms of Cd, Cu, Zn and Pb, in the forms of carbonates and Fe/ Mn oxide in water, the combination of Cu with organic matter and form, and the proportion of the residue form at each section have been studied.