Statistical downscaling of summer temperature extremes in northern China

Two approaches of statistical downscaling were applied to indices of temperature extremes based on percentiles of daily maximum and minimum temperature observations at Beijing station in summer during 1960-2008. One was to downscale daily maximum and minimum temperatures by using EOF analysis and stepwise linear regression at first, then to calculate the indices of extremes; the other was to directly downscale the percentile-based indices by using seasonal large-scale temperature and geo-potential height records. The cross-validation results showed that the latter approach has a better performance than the former. Then, the latter approach was applied to 48 meteorological stations in northern China. The cross-validation results for all 48 stations showed close correlation between the percentile-based indices and the seasonal large-scale variables. Finally, future scenarios of indices of temperature extremes in northern China were projected by applying the statistical downscaling to Hadley Centre Coupled Model Version 3 (HadCM3) simulations under the Representative Concentration Pathways 4.5 (RCP 4.5) scenario of the Fifth Coupled Model Inter-comparison Project (CMIP5). The results showed that the 90th percentile of daily maximum temperatures will increase by about 1.5℃, and the 10th of daily minimum temperatures will increase by about 2℃ during the period 2011-35 relative to 1980-99.     

Records of the Moon‐forming impact and the 470 Ma disruption of the L chondrite parent body in the asteroid belt from U‐Pb apatite ages of Novato (L6)

Novato, a newly observed fall in the San Francisco Bay area, is a shocked and brecciated L6 ordinary chondrite containing dark and light lithologies. We have investigated the U‐Pb isotope systematics of coarse Cl‐apatite grains of metamorphic origin in Novato with a large geometry ion microprobe. The U‐Pb systematics of Novato apatite reveals an upper intercept age of 4472 ± 31 Ma and lower intercept age of 473 ± 38 Ma. The upper intercept age is within error identical to the U‐Pb apatite age of 4452 ± 21 Ma measured in the Chelyabinsk LL5 chondrite. This age is interpreted to reflect a massive collisional resetting event due to a large impact associated with the peak arrival time at the primordial asteroid belt of ejecta debris from the Moon‐forming giant impact on Earth. The lower intercept age is consistent with the most precisely dated Ar‐Ar ages of 470 ± 6 Ma of shocked L chondrites, and the fossil meteorites and extraterrestrial chromite relicts found in Ordovician limestones with an age of 467.3 ± 1.6 Ma in Sweden and China. The lower intercept age reflects a major disturbance related to the catastrophic disruption of the L chondrite parent body most likely associated with the Gefion asteroid family, which produced an initially intense meteorite bombardment of the Earth in Ordovician period and reset and degassed at least approximately 35% of the L chondrite falls today. We predict that the 470 Ma impact event is likely to be found on the Moon and Mars, if not Mercury.     

方斑东风螺两种养殖模式的比较

在室内水泥池，利用沙层自净养殖模式和直接铺沙养殖模式对不同规格的方斑东风螺（Babylonia areolata Link）进行了高密度养殖的研究。结果表明，沙层自净养殖模式养殖小螺、中螺、大螺组日均增重分别为0．031、0．088、0．098g／d，沙层NH4^＋-N最高含量ω分别为1．3、2．1、3．1mg,／L,H2S最高含量ω分别为0．03、0．07、0．14mg／L．各规格组东风螺保持正常生长和活动，成活率92．9％以上；直接铺沙养殖模式养殖小螺、中螺、大螺日均增重分别为：0．023、0．051、0．068g／d．成活率分别为95．2％、86．7％、84．9％，沙层NH4^＋-N最高含量ω达到13．7mg／L，H2S最高含量ω达到0．47mg／L，沙层底质恶化，东风螺活动异常、不摄食。可见，沙层自净养殖模式对方斑东风螺的生长、成活率、沙层水质控制效果显著，在一定程度上克服了直接铺沙养殖底质恶化问题。     

基于反射机制的MVC业务模块简化方案

简要介绍了MVC设计模式，对开发框架FrameServer的MVC实现过程进行丁研究，结合实例讨论了如何利用反射机制开发MVC业务模块，最后阐述了反射机制的优缺点。     

我国海水养殖珍珠业存在的问题及对策

在详细分析我国海水珍珠养殖业存在问题的基础上，提出了统一规划海区，定量、低密度和开展外海深水海区珍珠养殖；加速大型珍珠贝全人工养殖与育珠的研究，丰富养殖品种；建立良种场、实行马氏珠母贝种质复壮；加强技术推广，延长育珠期、提高珍珠质量；抓好珍珠深加工、开拓珍珠产业链；建立龙头企业，带动珍珠业向集约型发展等可持续发展对策。     

星系的恒星速度弥散度的归算方法

星系的恒星视向速度分布是星系动力学模型的重要观测约束,其特征参数包括速度弥散度、分布轮廓以及红移。这些参数对研究星系的动力学、结构和演化以及中央黑洞的质量等都具有重要的价值。该文全面总结了从星系光谱归算星系的恒星视向速度分布及其弥散度的各种方法,以及对观测和处理的一些要求。这些方法都假设星系谱线可看作是模板星光谱经多普勒位移并加宽后的线性叠加。提取尽可能多的星系内部恒星运动信息、减少模板星失配的影响、简化误差分析,是这些方法追求的目标。     

双星轨道拟合的研究进展

双星轨道拟合是天文学的一项基础性研究工作。其主要目的是给出双星系统的二体轨道参数,这些参数不仅是高精度、高网格密度星表参考架的必要组成部分,而且也为理解各种有关观测现象提供了必要的动力学基础;更重要的是,双星轨道拟合可以直接估计恒星物理和星系天文学等领域极有应用价值的恒星质量参数。因此,长期以来双星轨道拟合工作一直受到研究者的广泛关注。近年来,随着高精度的恒星运动学观测资料的大量积累,双星轨道拟合更成为天体测量和天体力学的一个共同的热点课题,有关研究也有了长足的进展。综述了双星轨道拟合的历史及现状,其中着重介绍了目前所用的主要观测资料和各种具体的拟合模型、拟合方法;简要描述了几种主要的双星星表;展望了今后双星轨道拟合工作的发展趋势。     

Topographic zonation of infiltration in the hilly loess region,north china

Field infiltration tests using portable rainfall infiltrometers were conducted in the Wangjiagou experimental basin in the hilly loess region of north China. Based on data collected at 27 sites, a topographic zonation of infiltration characteristics was observed. The average steady infiltration rate and the average ponding time decreased from the hilltop to the hillslope and further decreased to the gully wall. Such a zonation is closely related to the variations of topography, soil and land use conditions in the study area. A general infiltration model is proposed. Collected field data are used to establish the applicability of the proposed model in the study area.     

不同条件延缓未受精卵激活对鱼类细胞电融合的影响

泥鳅未受精卵先在合成卵巢液、郝氏液中分别浸泡15、20、30min,然后再受精孵化,统计发育情况,结果表明,合成卵巢液可有效延缓未受精卵遇水后被激活的时间,郝氏液对延缓未受精卵被激活也有一定作用,但效果比合成卵巢液差。用合成卵巢液配制不同浓度胰酶处理受体卵进行细胞电融合实验,胰酶质量浓度为5 mg/mL时,融合卵发育至囊胚期的比例比对照组(郝氏液)高2%,统计分析表明该差异是显著的(P<0.05);但发育至原肠期及孵出期的比例则与对照组无显著差异。胰酶质量浓度为2和1 mg/mL时,融合卵发育到各阶段的比例均低于对照组,统计分析表明两者的差异是显著的(P<0.05)。研究表明,溶液种类、胰酶浓度等对电融合卵的发育有明显的影响,但延缓受体卵的激活时间并不能提高电融合卵的出苗率。用郝氏液配制的2 mg/mL的胰酶溶液处理受体卵,可获得较高比例的融合鱼。     

Constraint on cosmological model with matter creation using complementary astronomical observations

The universe with adiabatic matter creation is considered. It is thought that the negative pressure caused by matter creation can play the role of a dark energy component, and drive the accelerating expansion of the universe. Using the Type Ia supernovae (SNe Ia) data, the observational Hubble parameter data, the Cosmic Microwave Background (CMB) data and the Baryonic Acoustic Oscillation (BAO) data, we make constraints on the cosmological parameters, assuming a spatially flat universe. Our results show that the model with matter creation is consistent with the SNe Ia data, while the joint constraints of all these observational data disfavor this model. If the cosmological constant is taken into account, a traditional model without matter creation is favored by the joint observations.