On-going generation of multiple forms of HIV-1 intersubtype recombinants in the Yunnan Province of China

Objectives: To investigate the molecular epidemiology of HIV in China's Yunnan Province, where the initial HIV-1 outbreak among injecting drug users (IDU) occurred in 1989, and to analyse the genesis and interrelationship of the epidemic with that in surrounding areas. Design: A molecular epidemiological investigation was conducted among IDU in three prefectures in Yunnan Province, including Wenshan (east), Honghe (southeast) and Dehong (west). Methods: Thirty-nine specimens were collected from consenting IDU in 2000-2001. The nucleotide sequences of 2.6 kb gag-RT and 340 base pair (bp) env (C2/V3) regions were determined. Phylogenetic tree and recombination breakpoint analyses were performed. Results: The circulating recombinant form (CRF), CRF08_BC, predominated in east Yunnan near Guangxi Province (89% in Wenshan and 81% in Honghe), whereas it was not detected in Dehong(0/14) in the west. In contrast, 71% (10/14) of the Dehong isolates were unique recombinant forms (URF), mostly between subtypes B' (Thailand variant of subtype B) and C, with distinct profiles of recombination breakpoints. The subtype B' accounts for the remaining 29% (4/14) of Dehong isolates. Interestingly, two Honghe isolates (2/16) shared some of the precise B'/C recombination breakpoints with CRF07_BC. Conclusion: New recombinant strains are arising continually in west Yunnan near the Myanmar border. Some appeared to be secondary recombinants derived from CRF07_BC that had further recombined with other strains. The uneven distribution of subtypes, CRF and URF, suggests the presence of independent transmission networks and clusters among IDU in Yunnan. (C) 2002 Lippincott Williams Wilkins.

白颊长臂猿Fosmid 基因组文库的构建

长臂猿和大猿、人类同属人猿超科，在许多生物学特性方面具有相似性，但是自与大猿的祖先分歧以来的约两千万年的时间里，长臂猿染色体进化速度快于人猿超科其他物种和其他灵长类物种，出现了高度重排的核型。利用长臂猿染色体特异涂色探针已在人的染色体上探测到至少80个染色体断裂位点（synteny breakpoint），但是由于染色体荧光原位杂交技术的分辨率太低，仅有约5MB，所以迄今无从了解同源断裂位点两侧的序列特征，也就无法揭示长臂猿染色体快速重排的分子机制。 本论文旨在构建一个长臂猿Fosmid文库，以便为揭示长臂猿染色体快速进化的分子机制奠定基础。我选择了核型高度重排，且在长臂猿属中二倍染色体数目最多（2n=52）的代表物种——白颊长臂猿为材料，构建了一个白颊长臂猿 Fosmid 基因组文库。该文库含有192000个克隆，插入片段在30kb-45kb之间，假定白颊长臂猿的基因组大小按3.410ⅹ6kb计算，该文库至少有2.5倍的基因组覆盖率。通过对100个随机挑选的Fosmid 克隆进行末端测序，获得了200个序列标签。将这100个经末端测序的Fosmid 克隆与人的基因组进行BLAST比对以及将这些克隆制备成探针与白颊长臂猿和人的染色体中期分裂相进行荧光原位杂交（FISH），得到了这100个克隆在人基因组上的精确定位以及其中94个克隆在白颊长臂猿基因组上的精确定位,同时在这100个克隆中没有发现嵌合体克隆的存在。该文库以及所定位的克隆将为研究长臂猿以及其他高等灵长类染色体进化分子机制奠定基础，同时也为非人灵长类的比较基因组研究提供一个宝贵的资源。

Influence of Inter-Fiber Spacing and Interfacial Adhesion on Failure of Multi-Fiber Model Composites: Experiment and Numerical Analysis

The uniaxial tension experiments on glass-fiber-reinforced epoxy matrix composites reveal that the fragmentations of fibers display vertically aligned fracture, clustered fracture, coordinated fracture, and random fracture with the increase of inter-fiber spacing. The finite element analysis indicates that the fragmentations of fibers displaying different phenomena are due to the stress concentration as well as the inherent randomness of fiber defects, which is the dominant factor. The experimental results show that matrices adjacent to the fiber breakpoints all exhibit birefringent-whitening patterns for the composites with different interfacial adhesion strengths. The larger the extent of the interfacial debonding, the less the domain of the birefringent-whitening patterns. The numerical analysis indicates that the orientation of the matrix adjacent to a fiber breakpoint is caused by the interfacial shear stress, resulting in the birefringent-whitening patterns. The area of shear stress concentrations decides on the domain of the birefringent-whitening patterns.

波动方程辛几何算法三维叠前深度偏移及其并行实现

Oil and scientific groups have been focusing on the 3D wave equation prestack depth migration since it can solve the complex problems of the geologic structure accurately and maintain the wave information, which is propitious to lithology imaging. The symplectic method was brought up by Feng Kang firstly in 1984 and became the hotspot of numerical computation study. It will be widely applied in many scientific field of necessity because of its great virtue in scientific sense. This paper combines the Symplectic method and the 3-D wave equation prestack depth migration to bring up an effectual numerical computation method of wave field extrapolatation technique under the scientific background mentioned above. At the base of deep analysis of computation method and the performance of PC cluster, a seismic prestack depth migration flow considering the virtue of both seismic migration method and Pc cluster has formatted. The software, named 3D Wave Equation Prestack Depth Migration of Symplectic Method, which is based on the flow, has been enrolled in the National Bureau of Copyright (No. 0013767). Dagang and Daqing Oil Field have now put it into use in the field data processing. In this paper, the one way wave equation operator is decompounded into a phase shift operator and a time shift operator and the correct item with high rank Symplectic method when approaching E exponent. After reviewing eliminating alias frequency of operator, computing the maximum angle of migration and the imaging condition, we present the test result of impulse response of the Symplectic method. Taking the imaging results of the SEG/EAGE salt and overthrust models for example and seeing about the imaging ability with complex geologic structure of our software system, the paper has discussed the effect of the selection of imaging parameters and the effectuation on the migration result of the seismic wavelet and compared the 2-D and 3-D prestack depth migration result of the salt mode. We also present the test result of impulse response with the overthrust model. The imaging result of the two international models indicates that the Symplectic method of 3-D prestack depth migration accommodates great transversal velocity variation and complex geologic structure. The huge computing cost is the key obstruction that 3-D prestack depth migration wave equation cannot be adopted by oil industry. After deep analysis of prestack depth migration flow and the character of PC cluster ,the paper put forward :i)parallel algorithms in shot and frequency domain of the common shot gather 3-D wave equation prestack migration; ii)the optimized setting scheme of breakpoint in field data processing; iii)dynamic and static load balance among the nodes of the PC cluster in the 3-D prestack depth migration. It has been proven that computation periods of the 3-D prestack depth migration imaging are greatly shortened given that adopting the computing method mentioned in the paper. In addition,considering the 3-D wave equation prestack depth migration flow in complex medium and examples of the field data processing, the paper put the emphasis on: i)seismic data relative preprocessing, ii) 2.5D prestack depth migration velocity analysis, iii)3D prestack depth migration. The result of field data processing shows satisfied application ability of the flow put forward in the paper.