喷药机器人辅助视觉系统中超声测距数据的采集与处理

详细介绍了一种机器人超声测距系统,测距范围０．２～５ｍ,具体设计了基于单片机控制的３路超声测距系统的软、硬件,并介绍了该系统的构成、工作原理最后,通过实验获得３路测距数据,同时利用误差补偿的方法得到测距系统所要求的精度±４ｃｍ还给出了该单片机应用系统与上位机之间的通讯等利用本系统及其设计方法作为农业机器人辅助视觉系统,可以获得农作物远近以及大致形状等信息     

土水特征曲线预测非饱和黏土的抗剪强度

分别采用压力板法和滤纸法对一种孔隙比大致相同的黏土进行了测量土水特征曲线的试验, 并通过直剪仪试验测得不同含水率下该黏土的抗剪强度(简称强度). 试验结果表明: 压力板法和滤纸法测得的土水特征曲线大致相同; 同样竖向压力下, 抗剪强度随饱和度降低而增大, 但饱和度很低时强度反而减小. 饱和度主要影响黏聚力, 对内摩擦角的影响不大. 另外, 应用土水特征曲线对非饱和黏土的强度进行了预测. 通过引入有效饱和度的概念, 对非饱和土强度公式进行修正, 采用该公式预测非饱和土强度的精度比传统的平均骨架应力预测方法要高.     

江苏辐射沙洲海域最大可能潮差的计算与分析

为江苏辐射沙洲湿地开发和沿岸港口建设的需要,研究并建立了辐射沙洲海域及沿岸港口最大可能潮差的计算公式.利用改进的G·Godin潮汐调和分析程序对江苏省辐射沙洲海域的21个验潮站潮位资料进行分析.利用Delft3D数值模型对辐射沙洲海域潮流动力进行计算,得到模拟海域8个主要分潮的潮汐调和常数.运用统计分析方法,给出适用于江苏辐射沙洲海域最大可能潮差的计算公式.经验证,该公式简捷、实用,其相对误差绝对值均小于0.5%.     

工厂化水产养殖智能监控系统

采用PC工业控制计算机为上位监控机,以多个PLC可编程控制器和多个单片机系统为下位机,构成计算机集散监控系统.采用图像处理的方法对鱼病进行自动诊断和早期预报,采用移动GPRS无线通讯技术和互联网技术进行远程数据采集和监控.试验结果表明,该系统能对养殖水体的温度、氨氮含量、溶解氧含量等重要环境因子进行自动监测和控制,系统操作方便,人机界面友好,能在线进行鱼病诊断,使水产品能处在最适宜生长的环境下,达到增产、节能、减轻工人劳动强度的效果.     

Mutations in the pre-replication complex cause Meier-Gorlin syndrome

Meier-Gorlin syndrome (ear, patella and short-stature syndrome) is an autosomal recessive primordial dwarfism syndrome characterized by absent or hypoplastic patellae and markedly small ears1?3. Both pre- and post-natal growth are impaired in this disorder, and although microcephaly is often evident, intellect is usually normal in this syndrome. We report here that individuals with this disorder show marked locus heterogeneity, and we identify mutations in five separate genes: ORC1, ORC4, ORC6, CDT1 and CDC6. All of these genes encode components of the pre-replication complex, implicating defects in replication licensing as the cause of a genetic syndrome with distinct developmental abnormalities.     

Identification of genetic elements that autonomously determine DNA methylation states

Cytosine methylation is a repressive, epigenetically propagated DNA modification. Although patterns of DNA methylation seem tightly regulated in mammals, it is unclear how these are specified and to what extent this process entails genetic or epigenetic regulation. To dissect the role of the underlying DNA sequence, we sequentially inserted over 50 different DNA elements into the same genomic locus in mouse stem cells. Promoter sequences of approximately 1,000 bp autonomously recapitulated correct DNA methylation in pluripotent cells. Moreover, they supported proper de novo methylation during differentiation. Truncation analysis revealed that this regulatory potential is contained within small methylation-determining regions (MDRs). MDRs can mediate both hypomethylation and de novo methylation in cis, and their activity depends on developmental state, motifs for DNA-binding factors and a critical CpG density. These results demonstrate that proximal sequence elements are both necessary and sufficient for regulating DNA methylation and reveal basic constraints of this regulation.     

The San Francisco earthquake of 1906

Though among the most famous earthquakes in modern times, San Francisco (18 April 1906) has almost always been presented as nothing more than a great human disaster. While certainly that, we should regard it also as having had unusual significance in the development of seismology. Because the full extent of the San Andreas fault was thereafter recognized, and the association between faulting and earthquakes confirmed, we may consider the San Francisco earthquake of 1906 to be the first in which modern understanding of seismic causality prevailed.     

Detectable clonal mosaicism and its relationship to aging and cancer

In an analysis of 31,717 cancer cases and 26,136 cancer-free controls from 13 genome-wide association studies, we observed large chromosomal abnormalities in a subset of clones in DNA obtained from blood or buccal samples. We observed mosaic abnormalities, either aneuploidy or copy-neutral loss of heterozygosity, of >2 Mb in size in autosomes of 517 individuals (0.89%), with abnormal cell proportions of between 7% and 95%. In cancer-free individuals, frequency increased with age, from 0.23% under 50 years to 1.91% between 75 and 79 years (P = 4.8 × 10(-8)). Mosaic abnormalities were more frequent in individuals with solid tumors (0.97% versus 0.74% in cancer-free individuals; odds ratio (OR) = 1.25; P = 0.016), with stronger association with cases who had DNA collected before diagnosis or treatment (OR = 1.45; P = 0.0005). Detectable mosaicism was also more common in individuals for whom DNA was collected at least 1 year before diagnosis with leukemia compared to cancer-free individuals (OR = 35.4; P = 3.8 × 10(-11)). These findings underscore the time-dependent nature of somatic events in the etiology of cancer and potentially other late-onset diseases.