Independent adaptation to riverine habitats allowed survival of ancient cetacean lineages

The four species of "river dolphins" are associated with six separate great river systems on three subcontinents and have been grouped for more than a century into a single taxon based on their similar appearance. However, several morphologists recently questioned the monophyly of that group. By using phylogenetic analyses of nucleotide sequences from three mitochondrial and two nuclear genes, we demonstrate with statistical significance that extant river dolphins are not monophyletic and suggest that they are relict species whose adaptation to riverine habitats incidentally insured their survival against major environmental changes in the marine ecosystem or the emergence of Delphinidae.

Oddball Y(4140) as the molecular cousin of Y(3930)

In my talk, we present the dynamical study of Y(4140) and Y(3930) under the D-s*(D) over bar (s)* and D*(D) over bar* molecular assignments respectively The importance to theoretically and experimentally study their open-charm decay, hidden-charm decay, radiative decay and double-photon decay is proposed combing with the theoretical calculation of the decay behavior of Y(4140) and Y(3930) According to the recent new experimental progress made by Belle, we further indicate the reasonability of molecular explanation to Y(4140) Another event cluster around 4270 MeV in the J/psi Phi invariant mass spectrum of B -> KJ/psi Phi can provide us more hints to reveal the creation mechanism of molecular structure in B meson decay, which will be helpful to clarify the underlying structure of Y(4140) and Y(3930)

一种新型阻性板室（RPC）探测器的研制

气体探测器在核物理及粒子物理领域有着广泛的应用，尤其是阻性板室探测器，以其低廉的造价、优异的性能在各个大型实验室中都发挥着重要的作用。日本国家高能物理实验室(KEK)的Belle探测器，斯坦福大学斯坦福直线加速器中心(SLAC)的BaBar大型探测器，欧洲核子中心(CERN)的大型强子对撞机(LHC)的CMS与ATLAS谱仪，北京高能物理研究所(IHEP)的BESⅢ谱仪都使用阻性板室作为触发系统或缪子探测器。 随着HIRFL-CSR项目的完工。RIBLL2开展高能放射性束物理实验成为可能，而为了鉴别高能重离子碰撞实验中出射的高能轻粒子，有必要测量粒子的飞行时间(TOF)。为此，我们研制了单隙定时RPC，并作了简单性能测试。在CSR实验终端上，它可以作为传统塑料闪烁晶体+PMT时间探测器的替代，成为反应出射产物测量的大型探测器系统(4π)中的重要成员。 本论文对RPC的发展历史以及被广泛应用的原因做了深入而详细的研究，并对RPC的结构、性能、工作模式、特点、气体系统等进行了深入探讨。研制了一套单气隙RPC探测器样机，测设了一些相关性能，并对所遇到问题的产生原因以及解决方案进行了分析。为了测试RPC的需要，搭建了一套多组分工作气体配气系统，论文中还对包括质量流量计的选定，相关配件的选择，以及后期整个配气系统的组装与调试进行了详细描述