Two newly identified genetic determinants of pigmentation in Europeans

We present results from a genome-wide association study for variants associated with human pigmentation characteristics among 5,130 Icelanders, with follow-up analyses in 2,116 Icelanders and 1,214 Dutch individuals. Two coding variants in TPCN2 are associated with hair color, and a variant at the ASIP locus shows strong association with skin sensitivity to sun, freckling and red hair, phenotypic characteristics similar to those affected by well-known mutations in MC1R.     

Genetic determinants of hair, eye and skin pigmentation in Europeans

Hair, skin and eye colors are highly heritable and visible traits in humans. We carried out a genome-wide association scan for variants associated with hair and eye pigmentation, skin sensitivity to sun and freckling among 2,986 Icelanders. We then tested the most closely associated SNPs from six regions--four not previously implicated in the normal variation of human pigmentation--and replicated their association in a second sample of 2,718 Icelanders and a sample of 1,214 Dutch. The SNPs from all six regions met the criteria for genome-wide significance. A variant in SLC24A4 is associated with eye and hair color, a variant near KITLG is associated with hair color, two coding variants in TYR are associated with eye color and freckles, and a variant on 6p25.3 is associated with freckles. The fifth region provided refinements to a previously reported association in OCA2, and the sixth encompasses previously described variants in MC1R.     

Resequencing of 31 wild and cultivated soybean genomes identifies patterns of genetic diversity and selection

We report a large-scale analysis of the patterns of genome-wide genetic variation in soybeans. We re-sequenced a total of 17 wild and 14 cultivated soybean genomes to an average of approximately ×5 depth and >90% coverage using the Illumina Genome Analyzer II platform. We compared the patterns of genetic variation between wild and cultivated soybeans and identified higher allelic diversity in wild soybeans. We identified a high level of linkage disequilibrium in the soybean genome, suggesting that marker-assisted breeding of soybean will be less challenging than map-based cloning. We report linkage disequilibrium block location and distribution, and we identified a set of 205,614 tag SNPs that may be useful for QTL mapping and association studies. The data here provide a valuable resource for the analysis of wild soybeans and to facilitate future breeding and quantitative trait analysis.     

基于变阈值量化误差分散的半调水印算法

为解决半调(二值)图中直接嵌入水印引起的图像质量下降问题,提出一种基于变阈值量化误差分散的水印算法.通过分析打印-扫描(P-S)过程对图像的影响,得出抵抗P-S过程的半调图应具有绿噪声特性的结论;在构造水印模板和量化阈值变化规则的基础上,充分利用误差分散半调过程嵌入水印.仿真结果表明:在嵌入相同数据量时,该算法较直接嵌入法有更好的水印不可感知性;当图像遭受随机涂改、裁剪、加噪、对比度降低和低通滤波攻击时,仍能够正确提取其中嵌入的水印.     

黏土中倾斜螺旋桩的水平承载性能数值模拟及理论研究

为研究黏土中螺旋桩倾斜单桩的水平承载性能,基于非线性有限元软件ABAQUS建立有限元分析模型.通过数值模拟结果与已有螺旋桩软土地基抗拔试验及砂土地基水平承载试验的对比分析,验证了该数值模型的准确性与可行性.探讨了不同倾斜角度下叶片数量和首层叶片埋深对螺旋桩水平承载性能的影响规律.结果 表明:叶片数量对倾斜螺旋桩的水平承...     

含水率及夹层厚度对软弱夹层强度影响分析

软弱夹层对斜坡及围岩稳定性影响较大,对其剪切力学特性的研究具有实际工程意义。巴东组第三段(T₂b³)特殊岩体特性使风化后的软弱夹层和地下水中含有较多CaCO₃,使软弱夹层力学性质发生改变。基于此,以三峡库区巴东组第三段泥灰岩和层间软弱夹层为研究对象,对土-岩剪切试样进行室内直剪试验及微计算机断层扫描试验、电镜扫描试验,从宏微观角度重点研究含水率、夹层厚度及CaCO₃含量对软弱夹层抗剪强度的影响规律及动态特性。研究表明:CaCO₃通过降低土体孔隙率和改变土颗粒形态提升内摩擦角,通过增强土体胶结能力提升内聚力,从而增大其抗剪强度。低CaCO₃含量下,试样抗剪强度随含水率的增大而减小;高CaCO₃含量下,18%含水率以下时,抗剪强度随含水率的增大而增大,而到22%时抗剪强度突降。低法向应力下,试样抗剪强度受夹层厚度影响较小且随CaCO₃含量的增大而增大;高法向应力下,从高夹层厚度低CaCO₃含量到...