Quantum peculiarities of the primordial hydrogen recombination

Some problems of the two-photon decay of highly excited atomic hydrogen and helium levels are considered. The necessary accuracy of calculating the transition probabilities is shown to require abandoning the purely dipole approximation in the theory of atomic hydrogen radiation. The range of applicability of the perturbation theory to this process is discussed. We suggest a new mechanism of the Lyman photon redistribution due to very close locations of the 20P and 19P levels in the hydrogen and deuterium atoms, respectively (hydrogen-deuterium resonance).     

基于整合理论的高校教师管理

整合理论实质就是对组织所拥有的资源进行优化配置,使其协调发展,产生最大效益.对于高校,教师是所拥有的不可缺少,最具有潜力的资源,这种资源所发挥的协同作用存在巨大的潜力.从整合理论的角度,分析了高校教师管理方面的整合问题,提出了高校教师管理过程中应该注意的问题.     

A Rigid-Field Hydrodynamics approach to modelling the magnetospheres of massive stars

We introduce a new Rigid-Field Hydrodynamics approach to modelling the magnetospheres of massive stars in the limit of very strong magnetic fields. Treating the field lines as effectively rigid, we develop hydrodynamical equations describing the one-dimensional flow along each, subject to pressure, radiative, gravitational and centrifugal forces. We solve these equations numerically for a large ensemble of field lines to build up a three-dimensional time-dependent simulation of a model star with parameters similar to the archetypal Bp star σ Ori E. Since the flow along each field line can be solved independently of other field lines, the computational cost of this approach is a fraction of an equivalent magnetohydrodynamical treatment.
The simulations confirm many of the predictions of previous analytical and numerical studies. Collisions between wind streams from opposing magnetic hemispheres lead to strong shock heating. The post-shock plasma cools initially via X-ray emission, and eventually accumulates into a warped, rigidly rotating disc defined by the locus of minima of the effective (gravitational plus centrifugal) potential. However, a number of novel results also emerge. For field lines extending far from the star, the rapid area divergence enhances the radiative acceleration of the wind, resulting in high shock velocities (up to  ∼3000 km s⁻¹  ) and hard X-rays. Moreover, the release of centrifugal potential energy continues to heat the wind plasma after the shocks, up to temperatures around twice those achieved at the shocks themselves. Finally, in some circumstances the cool plasma in the accumulating disc can oscillate about its equilibrium position, possibly due to radiative cooling instabilities in the adjacent post-shock regions.     

Virialization of cosmological structures in models with time-varying equation of state

We study the virialization of the cosmic structures in the framework of flat cosmological models where the dark energy component plays an important role in the global dynamics of the Universe. In particular, our analysis focuses on the study of the spherical matter perturbations, as the latter decouple from the background expansion, start to 'turn around' and finally collapse. We generalize this procedure, taking into account models with an equation of state which vary with time, and provide a complete formulation of the cluster virialization attempting to address the non-linear regime of structure formation. In particular, assuming that clusters have collapsed prior to the epoch of z _f≃ 1.4, in which the most distant cluster has been found, we show that the behaviour of the spherical collapse model depends on the functional form of the equation of state.