Evolution of binary stars and the effect of tides on binary populations

We present a rapid binary-evolution algorithm that enables modelling of even the most complex binary systems. In addition to all aspects of single-star evolution, features such as mass transfer, mass accretion, common-envelope evolution, collisions, supernova kicks and angular momentum loss mechanisms are included. In particular, circularization and synchronization of the orbit by tidal interactions are calculated for convective, radiative and degenerate damping mechanisms. We use this algorithm to study the formation and evolution of various binary systems. We also investigate the effect that tidal friction has on the outcome of binary evolution. Using the rapid binary code, we generate a series of large binary populations and evaluate the formation rate of interesting individual species and events. By comparing the results for populations with and without tidal friction, we quantify the hitherto ignored systematic effect of tides and show that modelling of tidal evolution in binary systems is necessary in order to draw accurate conclusions from population synthesis work. Tidal synchronism is important but, because orbits generally circularize before Roche lobe overflow, the outcome of the interactions of systems with the same semilatus rectum is almost independent of eccentricity. It is not necessary to include a distribution of eccentricities in population synthesis of interacting binaries; however, the initial separations should be distributed according to the observed distribution of semilatera recta rather than periods or semimajor axes.     

The cluster substructure–alignment connection

Using a sample of 903 APM clusters we investigate whether their dynamical status, as evidenced by the presence of significant substructures, is related to the large-scale structure of the Universe. We find that the cluster dynamical activity is strongly correlated with the tendency of clusters to be aligned with their nearest neighbour and in general with the nearby clusters that belong to the same supercluster. Furthermore, dynamically active clusters are more clustered than the overall cluster population. These are strong indications that clusters develop in a hierarchical fashion by anisotropic merging along the large-scale filaments within which they are embedded.     

ON THE FORMATION AND MAINTENANCE MECHANISMS OF THE COLD WATER MASS OF THE YELLOW SEA

An analytical study is made on the formation of the Cold Water Mass of the Yellow Sea (CWYS) and the relevant thermally driven circulation. The temperature and velocity field, obtained by solving the coupled equations of motion and heat conduction, show that, in summer, the CWYS has a horizontal cyclonic circulation (component) with vertical upwelling in the middle and downwelling at the edges, that the vertical convection (u-w components) occurs only within a thin layer near the thermocline. and that the deeper layer remains almost motionless. This current structure represents well the mechanisms responsible for the maintenance of the thermocline or CWYS during the wanner months. Comparisons between the theoretical and observed temperatures show very good qualitative and quantitative agreements for corresponding seasons.     

Precision timing measurements of PSR J1012+5307

We present results and applications of high-precision timing measurements of the binary millisecond pulsar J1012+5307. Combining our radio timing measurements with results based on optical observations, we derive complete 3D velocity information for this system. Correcting for Doppler effects, we derive the intrinsic spin parameters of this pulsar and a characteristic age of 8.6±1.9 Gyr . Our upper limit for the orbital eccentricity of only 8×10⁻⁷ (68 per cent confidence level) is the smallest ever measured for a binary system. We demonstrate that this makes the pulsar an ideal laboratory in which to test certain aspects of alternative theories of gravitation. Our precision measurements suggest deviations from a simple pulsar spin-down timing model, which are consistent with timing noise and the extrapolation of the known behaviour of slowly rotating pulsars.     

2-D or 3-D interpretation of conductivity anomalies: example of the Rhine-Graben conductivity anomaly

Summary. Evidence of a conductivity anomaly in the Rhine-Graben was first given about 15 years ago and consequently led to the definition of various models of induction in the region for periods ranging from a few minutes to a few hours. These models reflect two antagonistic ways of explaining the observed anomalous variations of the magnetic field: direct induction in a two-dimensional (2-D) structure or static distortion of telluric currents by the resistive crystalline Vosges (France) and Schwarzwalde (Germany) massifs. We discuss the two approaches using a simple formalism. In particular, we show that the self-induction related to the anomalous currents flowing in the Rhine-Graben is negligible for periods larger than 1000 s, and that, even though the static distortion of telluric currents does account for the observed anomaly, 2-D models can explain some of its features. We also show how the channelled currents are induced in the large sedimentary basins surrounding the area under study.
An experimental verification of this result is given.     

Stabilization of Bottom Hole Temperature With Finite Circulation Time and Fluid Flow

As an alternative to finite element or finite difference modelling, analytical solutions are derived by the method of Laplace transformation and numerical results obtained for several models of the bottom hole temperature stabilization. Included in the models are the finite circulation time, the thermal property contrast between the borehole mud and the surrounding formation, and the presence of radial or lateral fluid flow in the formation, all of which are found to have significant effects on the dissipation of the thermal disturbance induced by drilling.
The mud circulation is considered to have the effect of either maintaining the borehole mud at a constant temperature or supplying a constant amount of heat per unit length per unit time to the borehole. For small circulation times, the former reduces to the 'zero circulation' model in which the mud circulation creates an instantaneous temperature anomaly at the hole bottom; for small borehole radii, the latter reduces to the line source model and the traditional 'Homer plot'.
For typical drilling operations in which the bottom hole temperatures are measured several hours to several tens of hours after the hole is shut in, the new models generally predict higher equilibrium formation temperatures than does the Horner plot. However, predictions from the various models converge if the BHTs are taken after the hole has been shut in for a period which is greater than about five times the circulation period.     

黄金新药源与豫西含金植物

黄金可以入药，历代本草均有记载。但因不溶性金被人体吸收极微，内服有一定毒性，加之其价格昂贵及一些药理学和比较复杂的检测处理与技术加工问题，不能普遍应用。自然界许多动植物都是聚金能手，特别是生长于富金岩石及金矿床风化土壤中的植物含金一般较高，部分动物因以含金植物为食，体内也含一定量的金，并且有些动植物本身就是中药材和食物。据此建议采取一定手段将含金较高、但未达工业品级的岩石，通过生物循环把金聚集至动、植物体内，金与动植物体内蛋白质等有机质结合成金的有机络合物，将此类动植物用于医疗或食疗，既可减小金的毒性，便于人体吸收，又可把未达工业品级的含金岩石利用起来。豫西某构造蚀变岩金矿，其上覆土壤中生长着含金植物，这些植物灰分中含金４×１０－９～９８×１０－９，其中以野苋菜的籽和叶灰分中含金最高（含金７５×１０－９～９８×１０－９），看来在本区用野苋菜籽和叶灰分中金含量进行找矿是可行的