Linkage disequilibrium in the human genome

With the availability of a dense genome-wide map of single nucleotide polymorphisms (SNPs), a central issue in human genetics is whether it is now possible to use linkage disequilibrium (LD) to map genes that cause disease. LD refers to correlations among neighbouring alleles, reflecting 'haplotypes' descended from single, ancestral chromosomes. The size of LD blocks has been the subject of considerable debate. Computer simulations and empirical data have suggested that LD extends only a few kilobases (kb) around common SNPs, whereas other data have suggested that it can extend much further, in some cases greater than 100 kb. It has been difficult to obtain a systematic picture of LD because past studies have been based on only a few (1-3) loci and different populations. Here, we report a large-scale experiment using a uniform protocol to examine 19 randomly selected genomic regions. LD in a United States population of north-European descent typically extends 60 kb from common alleles, implying that LD mapping is likely to be practical in this population. By contrast, LD in a Nigerian population extends markedly less far. The results illuminate human history, suggesting that LD in northern Europeans is shaped by a marked demographic event about 27,000-53,000 years ago.     

Synthetic biology: engineering Escherichia coli to see light

We have designed a bacterial system that is switched between different states by red light. The system consists of a synthetic sensor kinase that allows a lawn of bacteria to function as a biological film, such that the projection of a pattern of light on to the bacteria produces a high-definition (about 100 megapixels per square inch), two-dimensional chemical image. This spatial control of bacterial gene expression could be used to 'print' complex biological materials, for example, and to investigate signalling pathways through precise spatial and temporal control of their phosphorylation steps.     

企业研发团队知识共享影响因素的实证研究

基于知识共享理论和研发团队知识共享特征和影响因素,提出企业研发团队知识共享影响因素概念模型及理论假设,并运用调查问卷和结构方程模型对研发团队知识共享影响因素进行实证研究.结果表明,知识提供者、接受者、共享手段和共享双方关系4因素对研发团队知识共享水平有显著影响,而知识共享文化对知识共享水平影响作用不显著.提出了提高企业研发团队知识共享水平的对策与建议.     

基于Simulink的动态电路分析

介绍了Simulink应用于动态电路仿真分析的方法,以一个实例详述了图形输入式建模、参数设置、仿真配置、Matlab绘图分析等步骤．指出了联合运用To File、To Workspace和Scope模块,实现不同参数情况下仿真分析的优越性．     

数学分析在高等代数中的某些应用

高等代数中的某些问题,若用代数学的方法解决起来可能相当繁琐,但若结合数学分析的方法,则问题往往会迎刃而解．该文使用数学分析中的函数连续性和无穷区间的广义积分知识解决某些矩阵问题和二次型问题．     

MATLAB应用于离散时间系统分析的教学探讨

在离散时间系统分析的课堂教学中，借助科学计算软件MATLAB能在阐述概念的同时。避免过多的手动运算，即时给出相关结果和函数图形，使得在有限的时间内展现整个系统分析的流程，节省了时间，改善了授课效果．     

基于生态足迹法的黑龙江省林场所生态安全研究

为做好林场所生态安全评估,对林场所的经营管理做出积极调整,使林场所生态系统能够发挥更大的碳汇作用,成为我国实现碳中和、碳达峰目标进程中重要的“碳汇”平台,通过以黑龙江省伊春市青山林场所为例,在生态足迹法基础上,建立林场所生态承载力和生态足迹计算模型,定量分析2018年林场及经营所的整体生态安全和资源开发情况。结果表明：2018年,青山林场所生态安全处于可持续发展和生态协调阶段;生态空间总体呈现盈余状态,其中林地生态空间盈余为855.20 hm2,约占林地生态承载力的31.4%。可见林场所生态仍在区域中发挥着巨大的经济效益、生态效益和社会效益。