松嫩草原碱化草甸朝鲜碱茅光合生理生态特性的研究

在松嫩平原碱化草甸生长季中期,朝鲜碱茅不同龄级叶片净光合速率的日变化均为双峰曲线,第一个峰值出现在12:00左右,第二峰值出现在17:00左右;各龄级叶片中以4 a叶片的净光合速率最高,5 a叶片次之,3 a叶片最低.朝鲜碱茅为C3植物,光补偿点为56 μmol/ (m2·s),光饱和点为1 800 μmol/ (m2 ·s),光半饱和点为600 μmol/ (m2·s),光近饱和点为1 500 μmol/ (m2·s).     

扩充修正程序的一些基本结果

文献[4,5]为修正程序提出了一种包含经典否定的扩充,其关键特征在于能够区分“没有知识”和“具有否定的知识”,即区别“不知道”和“知道为否”。在这篇文章中,除了为该扩充修正程序提出了计算其合法修正的算法外,更重要的是,还研究了它的一些基本特征。这些特征形式化地表明了扩充修正程序的本质。     

盐碱胁迫对羊草可溶性蛋白质含量的影响

利用盆栽实验,对幼苗期灰绿和黄绿两个生态型羊草用NaCl和Na2CO3进行胁迫后,采用紫外分光光度法对可溶性蛋白含量进行了测定.定量分析结果表明,在不同浓度NaCl和Na2CO3胁迫条件下,灰绿型和黄绿型羊草可溶性蛋白质含量分别是对照的2.52～3.52倍,4.87～10.32倍,1.60～3.58倍和1.95～6.67倍.灰绿型和黄绿型羊草可溶性蛋白质含量在NaCl浓度为100 mmol/L和25 mmol/L,Na2CO3浓度为100 mmol/L和50 mmol/L时达到最高值.由此表明,灰绿型和黄绿型羊草具有一定的耐盐碱能力,且灰绿型羊草的耐盐碱能力高于黄绿型羊.     

The clonal and mutational evolution spectrum of primary triple-negative breast cancers

Primary triple-negative breast cancers (TNBCs), a tumour type defined by lack of oestrogen receptor, progesterone receptor and ERBB2 gene amplification, represent approximately 16% of all breast cancers. Here we show in 104 TNBC cases that at the time of diagnosis these cancers exhibit a wide and continuous spectrum of genomic evolution, with some having only a handful of coding somatic aberrations in a few pathways, whereas others contain hundreds of coding somatic mutations. High-throughput RNA sequencing (RNA-seq) revealed that only approximately 36% of mutations are expressed. Using deep re-sequencing measurements of allelic abundance for 2,414 somatic mutations, we determine for the first time-to our knowledge-in an epithelial tumour subtype, the relative abundance of clonal frequencies among cases representative of the population. We show that TNBCs vary widely in their clonal frequencies at the time of diagnosis, with the basal subtype of TNBC showing more variation than non-basal TNBC. Although p53 (also known as TP53), PIK3CA and PTEN somatic mutations seem to be clonally dominant compared to other genes, in some tumours their clonal frequencies are incompatible with founder status. Mutations in cytoskeletal, cell shape and motility proteins occurred at lower clonal frequencies, suggesting that they occurred later during tumour progression. Taken together, our results show that understanding the biology and therapeutic responses of patients with TNBC will require the determination of individual tumour clonal genotypes.     

The genomic basis of adaptive evolution in threespine sticklebacks

Marine stickleback fish have colonized and adapted to thousands of streams and lakes formed since the last ice age, providing an exceptional opportunity to characterize genomic mechanisms underlying repeated ecological adaptation in nature. Here we develop a high-quality reference genome assembly for threespine sticklebacks. By sequencing the genomes of twenty additional individuals from a global set of marine and freshwater populations, we identify a genome-wide set of loci that are consistently associated with marine-freshwater divergence. Our results indicate that reuse of globally shared standing genetic variation, including chromosomal inversions, has an important role in repeated evolution of distinct marine and freshwater sticklebacks, and in the maintenance of divergent ecotypes during early stages of reproductive isolation. Both coding and regulatory changes occur in the set of loci underlying marine-freshwater evolution, but regulatory changes appear to predominate in this well known example of repeated adaptive evolution in nature.     

A unique regulatory phase of DNA methylation in the early mammalian embryo

DNA methylation is highly dynamic during mammalian embryogenesis. It is broadly accepted that the paternal genome is actively depleted of 5-methylcytosine at fertilization, followed by passive loss that reaches a minimum at the blastocyst stage. However, this model is based on limited data, and so far no base-resolution maps exist to support and refine it. Here we generate genome-scale DNA methylation maps in mouse gametes and from the zygote through post-implantation. We find that the oocyte already exhibits global hypomethylation, particularly at specific families of long interspersed element 1 and long terminal repeat retroelements, which are disparately methylated between gametes and have lower methylation values in the zygote than in sperm. Surprisingly, the oocyte contributes a unique set of differentially methylated regions (DMRs)--including many CpG island promoters--that are maintained in the early embryo but are lost upon specification and absent from somatic cells. In contrast, sperm-contributed DMRs are largely intergenic and become hypermethylated after the blastocyst stage. Our data provide a genome-scale, base-resolution timeline of DNA methylation in the pre-specified embryo, when this epigenetic modification is most dynamic, before returning to the canonical somatic pattern.     

改进的适用于移动通信的代理签名方案

针对适用于移动通信的代理保护代理签名方案和代理聚合签名方案存在的不满足强不可伪造性和强不可否认性的安全缺陷,提出了2个改进的代理签名方案,当代理私钥生成时,添加一个随机数,使得原始签名者不能够假冒代理签名者进行伪造攻击.安全性分析与证明表明：改进方案满足代理签名的基本安全性质,在随机预言机下是可证明安全的;同时,在适应性选择消息攻击下,其代理生成协议是安全的.     

基于H.264高档次标准的一种新颖的8×8/4×4SATD硬件实现

支持8×8/4×4自适应变换是H.264高档次标准的一个重要特性,残差变换绝对值和(sumof absolute transformed difference,SATD)是各种模式下预测残差代价的评判准则。根据SATD的运算特点,提出一种高度并行的流水线结构,通过两级1-D变换实现2-D哈达码变换。采用3-2压缩器代替传统的加法器实现和值相加,提高了运算速度。在SMIC 0.13μm CMOS工艺库下的实验结果表明,利用上述思想设计的4×4 SATD以及8×8 SATD电路在300 MHz的时钟频率下每秒钟处理的像素数分别为4.8G和19.2G,远远超过了高清视频应用中1920×1080视频序列30帧/s的实时编码需求。     

Sorting nexin 3 mutation impairs development and neuronal function in <Emphasis Type="Italic">Caenorhabditis elegans</Emphasis>

The sorting nexins family of proteins (SNXs) plays pleiotropic functions in protein trafficking and intracellular signaling and has been associated with several disorders, namely Alzheimer’s disease and Down’s syndrome. Despite the growing association of SNXs with neurodegeneration, not much is known about their function in the nervous system. The aim of this work was to use the nematode Caenorhabditis elegans that encodes in its genome eight SNXs orthologs, to dissect the role of distinct SNXs, particularly in the nervous system. By screening the C. elegans SNXs deletion mutants for morphological, developmental and behavioral alterations, we show here that snx-3 gene mutation leads to an array of developmental defects, such as delayed hatching, decreased brood size and life span and reduced body length. Additionally, ?snx-3 worms present increased susceptibility to osmotic, thermo and oxidative stress and distinct behavioral deficits, namely, a chemotaxis defect which is independent of the described snx-3 role in Wnt secretion. ?snx-3 animals also display abnormal GABAergic neuronal architecture and wiring and altered AIY interneuron structure. Pan-neuronal expression of C. elegans snx-3 cDNA in the ?snx-3 mutant is able to rescue its locomotion defects, as well as its chemotaxis toward isoamyl alcohol. Altogether, the present work provides the first in vivo evidence of the SNX-3 role in the nervous system.     

基于平面靶标的相机内部参数标定精度分析

相机内部参数标定是实现机器视觉测量的必要环节.目前常用的标定方法有Tsai两步法、DLT方法以及基于平面标靶的张正友法等.张正友法简单易行,因而得到广泛应用,标定精度取决于平面靶标的制作精度、图像特征点坐标的提取精度、镜头畸变、靶标摆放数目以及位姿分布等.对张正友标定方法的精度进行探讨,分析各影响因素对标定精度的影响,提出基于均匀设计的思想进行靶标位姿分布的设计思想.仿真和实际测试证明,采用均匀设计的靶标布局明显提高相机内部参数标定精度.