In honor of the establishment of IMS China

I am extremely pleased that Science in China Series A: Mathematics is publishing this special issue in honor of the establishment of IMS China. The Institute of Mathematical Statistics     

Effects of structural change on half-metallicity of CoMnZ (Z=P, As, Sb): A first-principle study

The C1_b and Fm-3m phases of CoMnZ (Z=P, As, Sb) were studied via first-principle calculations. The C1_b CoMnZ exhibits half-metallicity and is more energetically stable than Fm-3m CoMnZ. Under volume distortions, CoMnP, CoMnAs, and CoMnSb can maintain half-metallicity for volume alterations of −16% to 16%, −20% to 11%, and −32% to 0%, respectively. Under tetragonal distortions, CoMnP, CoMnAs, and CoMnSb can maintain half-metallicity from a change of in-plane lattice constants of 0.500-0.580, 0.515-0.585, and 0.545-585 nm, respectively.     

Modeling and prediction of children’s growth data via functional principal component analysis

We use the functional principal component analysis (FPCA) to model and predict the weight growth in children. In particular, we examine how the approach can help discern growth patterns of underweight children relative to their normal counterparts, and whether a commonly used transformation to normality plays any constructive roles in a predictive model based on the FPCA. Our work supplements the conditional growth charts developed by Wei and He (2006) by constructing a predictive growth model based on a small number of principal components scores on individual’s past. This work was supported by National Natural Science Foundation of China (Grant No. 10828102), a Changjiang Visiting Professorship, the Training Fund of Northeast Normal University’s Scientific Innovation Project (Grant No. NENU-STC07002) and the National Institutes of Health Grant of USA (Grant No. R01GM080503-01A1).     

Removal of nitrate from groundwater by heterotrophic denitrification using the solid carbon source

Removal of nitrate from groundwater was investigated using biodegradable meal box(BMB) and poly(ε-caprolactone)(PCL) as carbon source and biofilm carrier.The experimental results show that nitrate in groundwater can be effectively removed using BMB and PCL as carbon source.Denitrification rates supported by BMB and PCL were 52.80 and 42.77 mg(NO3-N)/(m2h),respectively,at 30 ℃ and pH 7.5.The pH value of effluent ranged from 7 to 8,and NO2-N concentration was less than 0.1 mg/L.Compared with BMB,PCL could dec...     

Robust low-rank data matrix approximations

We review some recent approaches to robust approximations of low-rank data matrices. We consider the problem of estimating a low-rank mean matrix when the data matrix is subject to measurement errors as well as gross outliers in some of its entries. The purpose of the paper is to make various algorithms accessible with an understanding of their abilities and limitations to perform robust low-rank matrix approximations in both low and high dimensional problems.     

高分子共混物梯度相结构形成过程中的界面效应

通过在高分子共混物内部引入不同的第三相界面,系统地研究了退火热处理条件下该界面对于共混物梯度相形态形成的影响.对具有一定初始粒径的共混物体系或初始近似为均相的共混体系,在第三相界面的诱导下,均能形成梯度相形态.探讨了诱导界面间距与体系相结构的关系.结果表明,当两个诱导界面间距小于所生成梯度层厚度的两倍时,梯度结构趋于交叠.继续减小诱导界面间距,则梯度结构趋于消失,诱导界面间共混物中分散相粒子快速长大,界面的诱导作用遍布整个样片,证实了我们所提出的“高分子共混物中二维条件下界面诱导加速分散相粒子粗化凝聚”的结论.     

First dark matter search results from the PandaX-I experiment

We report on the first dark-matter (DM) search results from PandaX-I, a low threshold dual-phase xenon experiment operating at the China JinPing Underground Laboratory. In the 37-kg liquid xenon target with 17.4 live-days of exposure, no DM particle candidate event was found. This result sets a stringent limit for low-mass DM particles and disfavors the interpretation of previously-reported positive experimental results. The minimum upper limit, 3.7 × 10^?44 cm², for the spin-independent isoscalar DM-particle-nucleon scattering cross section is obtained at a DM-particle mass of 49GeV/c² at 90% confidence level.