Genome-wide association study of flowering time and grain yield traits in a worldwide collection of rice germplasm

A high-density haplotype map recently enabled a genome-wide association study (GWAS) in a population of indica subspecies of Chinese rice landraces. Here we extend this methodology to a larger and more diverse sample of 950 worldwide rice varieties, including the Oryza sativa indica and Oryza sativa japonica subspecies, to perform an additional GWAS. We identified a total of 32 new loci associated with flowering time and with ten grain-related traits, indicating that the larger sample increased the power to detect trait-associated variants using GWAS. To characterize various alleles and complex genetic variation, we developed an analytical framework for haplotype-based de novo assembly of the low-coverage sequencing data in rice. We identified candidate genes for 18 associated loci through detailed annotation. This study shows that the integrated approach of sequence-based GWAS and functional genome annotation has the potential to match complex traits to their causal polymorphisms in rice.     

The genome of the extremophile crucifer Thellungiella parvula

Thellungiella parvula is related to Arabidopsis thaliana and is endemic to saline, resource-poor habitats, making it a model for the evolution of plant adaptation to extreme environments. Here we present the draft genome for this extremophile species. Exclusively by next generation sequencing, we obtained the de novo assembled genome in 1,496 gap-free contigs, closely approximating the estimated genome size of 140 Mb. We anchored these contigs to seven pseudo chromosomes without the use of maps. We show that short reads can be assembled to a near-complete chromosome level for a eukaryotic species lacking prior genetic information. The sequence identifies a number of tandem duplications that, by the nature of the duplicated genes, suggest a possible basis for T. parvula's extremophile lifestyle. Our results provide essential background for developing genomically influenced testable hypotheses for the evolution of environmental stress tolerance.     

Differential space-time modulation in rapidly fading channels

Previously proposed differential modulation schemes for time-varying channels may not achieve the full transmit diversity and the maximum Doppler diversity simultaneously. Based on an existing basis expansion model, a new differential space-time code, which wisely combines interleaver/de-interleaver with traditonal space-time transmitting technique to overcome such limitation, .is presented. Two noncoherent differential decoders, named decision-feedback differential detector （DF-DD） and Viterbi-algorithmbased multiple-symbol-detection differential detector （ MSD-DD）, are also derived. We show that our design may recover data symbols with full antenna diversity and the maximum Doppler diversity at high signal-to-noise ratio. System performance is evaluated with simulations.     

Estimation and Inference in Semi-Functional Partially Linear Measurement Error Models

Journal of Systems Science and Complexity - This article studies the estimation and statistical inference problems of semi-functional partially linear regression models when the covariates in the...     

头盘微小间隙动态浮动理论研究

本文对微小浮动间隙的磁头浮动块的动态浮动性能进行了仿真计算。在考虑头盘碰撞的基础上,分析了磁头浮动块对冲击的响应。分析结果表明:在微小浮动间隙的头盘系统中,盘片表面粗糙度和外界干扰冲击对浮动块的浮动性能影响较大。新的动态浮动理论中,必须包含头盘磁撞的研究。     

SAm级防撞活动护栏碰撞仿真分析

针对目前高速公路中央分隔带开口处活动护栏防撞等级较低的问题,提出了一种SAm级混凝土活动护栏及一种新型连接装置.基于有限元的方法,建立车辆与护栏的碰撞模型,通过LS-DYNA对车辆与护栏碰撞过程进行求解,根据不同车型的碰撞结果分别在缓冲,阻挡和导向性能上对护栏的安全性能进行评价,其中小型车辆与护栏碰撞后的OIV(Occ...     

浅析排球副攻手的进攻打法、作用及效果

随着排球运动的发展,快变战术在排球运动技战术体系中的地位和作用越来越重要.排球副攻手作为快变战术的核心,其在排球比赛中作用的发挥越来越受到人们的关注.文章分析了排球副攻手的进攻打法,并对其进攻作用和效果进行了研究.     

固相萃取技术在环境中农药残留分析的研究进展

农药在环境中的广泛应用以及农药残留分析的困难,使得环境中农药的残留分析成为国际上环境科学研究的前沿和热点.固相萃取法（SPE）因高效、可靠、易实现自动化等优点,适用于农药残留物分析.本文对固相萃取的基本原理、影响因素和应用进展等方面进行了详细的阐述,就农药的检测方法（如LC、GC）做了总结概括.最后提出固相萃取在环境领域中农药残留分析的发展趋势是使用SPE-HPLC对极性差异很大,酸碱性范围很广的各种农药的多残留分析。     

Mg、Cd掺杂AlN电子结构的第一性原理计算

基于密度泛函理论（DFT）框架下的第一性原理的平面波超软赝势方法（USPP）,对Mg，Cd掺杂AlN的32原子超原胞体系进行了几何结构优化，从理论上给出了掺杂和 掺杂体系的晶体结构参数.计算了掺杂AlN晶体的结合能，电子态密度，差分电荷密度，并对计算结果进行了细致的分析.计算结果表明，相对于Cd，Mg在AlN晶体中可以提供更多的空穴，有利于形成更好的p型电导.