Expression of an N-terminal fragment of COP1 confers a dominant-negative effect on light-regulated seedling development in Arabidopsis

CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1) is an essential regulatory gene that plays a role in light control of seedling development in Arabidopsis. The COP1 protein possesses three recognizable structural domains: a RING finger zinc binding domain near the N terminus, followed by a coiled-coll domain and a domain with WD-40 repeats in the C-terminal half. To determine whether COP1 acts specifically as a light-inactivable repressor of photomorphogenic development and to elucidate the functional roles of the specific structural domains, mutant cDNAs encoding the N-terminal 282 amino acids (N282) of COP1 were expressed and analyzed in transgenic plants. High-level expression of the N282 fragment caused a dominant-negative phenotype similar to that of the loss-of-function cop1 mutants. The phenotypic characteristics include hypersensitivity of hypocotyl elongation to inhibition by white, blue, red, and far-red light stimuli. In the dark, N282 expression led to pleiotropic photomorphogenic cotyledon development, including cellular differentiation, plastid development, and gene expression, although it has no significant effect on the hypocotyl elongation. However, N282 expression had a minimal effect on the expression of stress- and pathogen-inducible genes. These observations support the hypothesis that COP1 is directly involved in the light control of seedling development and that it acts as a repressor of photomorphogenesis. Further, the results imply that the N282 COP1 fragment, which contains the zinc binding and colled-coil domains, is capable of interacting with either downstream targets or with the endogenous wild-type COP1, thus interfering with normal regulatory processes. The fact the N282 is able to interact with N282 and full-length COP1 in yeast provided evidence for the latter possibility.     

HIV infection among pregnant women in Lindi, Tanzania, 1989-1993

One obstacle to contain the HIV-1 epidemic in the general population in Africa is a lack of knowledge about how it is spread in rural areas. We examined 683 pregnant women in 1989 and 484 in 1993 who attended antenatal clinics in Lindi district, Tanzania to determine changes in the prevalence of HIV-1 in a remote area in East Africa. The prevalence rose from 0.44% in 1989 to 8.7% in 1993. Women with more than 1 partner (17.25% vs 2.78%), STD patients (42.4% vs 6.2%), women from urban areas (10.2% vs 3.57%) and patients younger than 21 years were more likely to have HIV antibodies. By logistic regression analysis, 1993 as year of testing was associated with the greatest risk for HIV seropositivity (P < 0.00002) followed by clinical signs of STD (P < 0.00005) and urban residence (P = 0.0275). Teaching of all women attending antenatal care how to minimize their future risk of acquiring HIV is urgently needed as one tool to prevent a fast spread of HIV throughout the continent.     

Variation in the size and distensibility of the pulmonary arteries in d-transposition of the great arteries

The relative size of the main pulmonary artery was determined from cineangiograms of 117 patients with d-transposition of the great arteries by calculating the ration between the diameters of the main pulmonary artery and aorta. The pulmonary artery was largest in patients with ventricular septal defect or patent ductus arteriosus, or both, because of increased pulmonary arterial pressure and flow. In patients with an intact ventricular septum or with left ventricular outflow tract obstruction, or both, the main pulmonary artery was approximately the size of the aorta. Two cases of d-transposition and gross dilatation of the main pulmonary artery and hypoplastic first branch pulmonary arteries are presented. In these cases the ratio between the diameters of the main pulmonary artery and aorta was greater than in any of the other 117 cases studied...     

随机采样移动轨迹时空热点区域发现及模式挖掘

针对随机采样条件下移动轨迹在时间轴分布疏密不均的特点,在将三维时空轨迹转换为一维时间投影数据的基础上,提出一种基于密集时间区间自动检测的时空热点区域发现与移动模式挖掘方法。通过自底向上的动态聚类方式以探测密集时间区间,进而在密集时间区间内进行移动轨迹的时空热点区域发现。最后,采用深度优先的序列模式挖掘算法挖掘频繁移动模式集合。基于合成数据的仿真试验,验证了算法在有效性及可扩展性方面均具有较好的性能。     

基于全局交互的图像语义理解方法

针对图像语义生成过程中图像信息易模糊的问题,提出基于双向门控循环单元(GRU)和图像信息全局交互相结合的图像语义生成模型,通过图像和文本数据进行正则化处理和文本向量映射方法,实现模型驱动的图像语义生成.实验结果表明,所提出模型能较好地解决数据稀疏和偏态问题,采用GUR单元可以进一步降低模型参数规模,加快算法收敛速度,有效抑制模型过拟合,提高图像内容的丰富度、准确性和逻辑性.     

基于多尺度空间划分与路网建模的城市移动轨迹模式挖掘

针对城市移动轨迹模式挖掘问题展开研究, 提出移动全局模式与移动过程模式相结合的挖掘方法, 即通过移动轨迹的起始位置点--终点位置点 (Origin-destination, OD点) 与移动过程序列分别进行移动全局模式与过程模式的发现. 在移动全局模式发现中, 提出了弹性多尺度空间划分方法, 避免了硬性等尺度网格划分对密集区域边缘的破坏, 同时增强了密集区域与稀疏区域的区分能力.在移动过程模式发现中, 提出了基于移动轨迹的路网拓扑关系模型构建方法, 通过路网关键位置点的探测抽取拓扑关系模型.最后基于空间划分集合与路网拓扑模型对原始 移动轨迹数据进行序列数据转换与频繁模式挖掘. 通过深圳市出租车历史 GPS 轨迹数据的实验结果表明, 该方法与现有方法相比在区域划分、数据转换等方面具有更好的性能, 同时挖掘结果语义更为丰富, 可解释性更强.     

宏观各向同性混杂岩力学特性及性状研究

本文主要在发展宏观各向同性混杂岩制作方法,并针对此类岩石进行一系列力学试验,以探讨岩块体积含量对整体力学特性及性状的影响。所设计的双动式压制模具施加有效压实应力较传统单动式均匀,可获得均匀性较高试体。此种压制试体方式,可制作力学性质多样混杂岩试体并可避免钻芯取样造成试体扰动。在理论模式预测方面,利用五种微观力学模式来预测不同岩块体积含量的各向同性混杂岩的杨氏模量及柏松比,并与试验结果进行比较,探讨以微观力学模式来预测宏观各向同性混杂岩整体力学特性的可行性。在破坏型态观察方面,利用笔者所设计的旋转式扫描仪,完整且连续的纪录破坏后岩芯试体的表面影像,并针对不同岩块体积含量及围压混杂岩的破坏型态进行分类与探讨。     

Serum high density lipoprotein and its relationship to cardiovascular disease risk factor variables in children—The bogalusa heart study

Serum high density lipoprotein is increasingly recognized as a negative risk for cardiovascular disease. The distribution and interrelationship of serum lipids, lipoproteins, anthropometric measurements and blood pressures were determined in some 5,000 children. Children had mean±S.D. α-lipoprotein cholesterol levels (mg/100 ml) of 36±15 at birth, 51±22 at 6 mo, 53±18 at 1 yr, 60±19 at preschool age (21/2−51/2 yr) and 68±22 at school age (5–14 yr), reflecting a sharp increase in α-lipoprotein between birth and school-age years, when these levels remained relatively stable through age 14. Although white children tended to have higher levels of total cholesterol and α-lipoprotein at birth than black children, during childhood this trend was reversed and the differences were pronounced in school-age children (p<0.0001). Unlike in adulthood, boys had slightly higher levels of α-lipoprotein than girls. The α-lipoprotein was negatively correlated with pre-β-lipoprotein and to a lesser extent with β-lipoprotein classes. There was an inverse relationship between α-lipoprotein and obesity with a consistently significant relationship (p<0.01) in older children (10–14 yr). Children with higher levels of α-lipoprotein have lower levels of blood pressure, β-lipoprotein and a lower obesity index.     

视觉手势识别综述

随着计算机视觉的发展和人机交互的需要,手势识别研究取得了蓬勃的发展。然而,很少有对手势识别进行全面分析、总结、评述的相关综述研究。 针对这一问题, 就基于计算机视觉的手势识别技术的发展现状展开综述, 系统地分析和梳理了近三十年来基于计算机视觉的手势识别技术,按照手势识别的流程,将手势识别分为检测分割、分析和识别3个主要步骤,并对每个步骤分别进行评述,总结归纳其适用范围及优缺点。最后对手势识别进行总结展望。