Molecular phylogeny of European and African Barbus and their West Asian relatives in the Cyprininae (Teleostei: Cypriniformes) and orogenesis of the Qinghai-Tibetan Plateau

The phylogenetic relationships of European and African Barbus and their West Asian relatives in Cyprininae remain largely unresolved. Consequently, little is known about the drivers of their evolution, including the possible association of uplifting of the Qinghai-Tibetan Plateau (QTP) with the early divergence of the subfamily. We use complete sequence data of the mitochondrial DNA gene encoding the protein cytochrome b (Cytb) to hypothesize the phylogeny of 85 species belonging to 47 genera in the Cyprininae plus 6 species from the Leuciscinae. We employ 6 other species from Cypriniformes as outgroup taxa and estimate divergence times. Our results indicate that European Barbus sensu stricto lineage including Aulopyge shares a common ancestor with specialized and highly specialized schizothoracins and the genera Cyprinion and Scaphiodonichtys. The common ancestor appears to have originated in the Qinghai-Tibetan Plateau (QTP) region about 19.4–17.8 Ma. Barbus sensu stricto lineage appears to have originated about 16.6–15.5 Ma. Small to medium sized African Barbus sensu lato appear to have had an Oriental origin about 19.1–15.3 Ma and are closely related to Asian Puntius. West Asian Carasobarbus lineage including large African Barbus sensu lato might have originated about 9.94 Ma, also in Oriental Realm and has a close relationship to Asian Neolissochilus and Tor. The large-sized Barbus sensu lato appear to have diverged from Carasobarbus about 7.7 Ma. Finally, the Cyprininae appear to have radiated rapidly into nine lineages and many sublineages from about 27.8 to 17.8 Ma, close to the time of the second-stage tectonic movements of the QTP. Our analyses provide evidence that the uplifting of the QTP drove early diversification of the Cyprininae. Our extensive sampling of species involving all of the important areas results in clear evolutionary scenario for the Cyprininae.     

SVM算法分析与研究

介绍了支持向量机(SVM)中广泛采用的算法——分解算法,总结了其收敛性证明的总体思路并对目前最流行的SVM算法库LIBSVM进行了详细的分析与研究.     

Novel trichromatic phosphor Co-doped with Eu, Tb in SiO2 gel matrix

The Eu, Tb co-doped SiO2 matrix tricolor fluorescence system was prepared by sol-gel technique. Red emission at 618 nm, green emission at 543 nm and blue emission at 350-500 nm were observed in the PL spectra of the sample, indicating that Eu^3＋, Eu^2＋ and Tb^3＋ ions coexisted in the matrix. In the co-doped sample, the blue emission of Eu^2＋ was much stronger than that of the sample single doped with Eu, which implied that the electron transfer between Eu^3＋ and Tb^3＋ maybe happened in the SiO2 matrix. The influences of the annealing temperature and Tb concentration on the PL spectra of the samples were investigated. The optimal doped concentration of Tb was determined to be 0.2% and the optimal annealing temperature 850℃. Annealed at 600℃, Tb^3＋ had a sensitizing effect on Eu^3＋ in the SiO2 matrix, and the emission intensity of Eu^3＋ in the Eu, Tb co-doped sample was more than four times that of the single doped sample, which could be attributed to the energy transfer from Tb^3＋ to Eu^3＋.     

Design and demonstration of a 0.22 THz gyrotron oscillator

Gyrotrons are the most powerful terahertz sources and have potential applications in many areas. A terahertz gyrotron oscillator with a pulsed solenoid producing up to an 8 T magnetic field has been designed, constructed and tested. In a 7.96 T magnetic field, 3 kW output power radiations at 0.22 THz frequency have been generated. Supported by the State Key Development Program of Basic Research of China (Grant No. 2007CB310400) and National Natural Science Foundation of China (Grant No. 1067611)     

纳秒激光加工生成硅量子点的发光性质研究

该文报道氧气、氮气或空气等不同氛围中用纳秒脉冲激光在硅基上加工生成量子点结构,发现这些样品在700 nm波长附近均有增强的光致发光(Photoluminescence,PL),且各样品的PL峰很相似;经适当退火处理后,在某些样品上观察到随机受激发光.通过第一性原理计算,发现各种量子点结构表面的成键类型与密度是形成PL发光增强的关键,并由此提出相应的物理模型.     

Polarization properties of an evanescent-wave pumped whispering gallery mode fibre laser

The polarization properties of an evanescent-wave pumped Whispering Gallery Mode(WGM) fibre laser have been investigated. It is found that there are two kinds of polarization lasing beam emitting from the evanescent-wave pumped WGM fibre laser under two different pump conditions.When the pump beam is strictly along the axial direction of an optical fibre,the lasing emission is transverse electric wave and the electrical vectors at emitting points are along the radial direction of the fibre,which forms a spe...     

消逝波激励及增益耦合光纤三色激光辐射

将石英光纤浸入低折射率的染料溶液中,泵浦光沿光纤轴向耦合进入光纤并以全反射方式沿光纤轴向传播,泵浦光的消逝波激励染料分子产生增益.由于增益区域与回音壁模式的消逝场区域在空间很好的重叠,因此显著地提高了泵浦效率,增加了沿光纤轴向的增益长度.将一根直径为265μm的石英光纤浸入三段激光染料溶液中,在622～632,504～518和427～434nm的3个波长范围内同时获得回音壁模式的激光辐射.在消逝波激励及增益耦合方式下,实现了同一根光纤中红绿蓝三色的回音壁模式激光辐射,由此形成一种新型的三色回音壁模式光纤激光器.本文同时从实验和理论方面讨论了回音壁模式激光沿光纤轴向的产生长度随泵浦能量变化的关系.     

新农村建设的绩效评价体系研究——基于武汉市洪山区青菱乡的实证分析

在参考指标体系的构建原则以及在借鉴和比较国内外现有研究成果的基础上,从“生产发展”、“生活富裕”、“村容整洁”、“乡风文明”、“管理民主”五个方面构建了一套由29个指标组成的用于评价新农村建设的指标体系。然后运用层次分析法确定各指标的权重．同时参照国家全面小康目标值的规定以及对其他研究成果中的目标值的借鉴分析制定出指标体系的目标值。在指标体系构建完毕和确定了评价权重和标准值的前提下,以武汉市洪山区青菱乡为实证分析对象．采用综合评价方法进行评价分析,给出了评分结果。最后,用调查的实际情况与评价结果进行对比,验证了指标体系的实用性和科学性。