The Control of Rinderpest in Tanzania between 1997 and 1998

In January 1997, Tanzania requested international assistance against rinderpest on the grounds that the virus had probably entered the country from southern Kenya. Over the next few months, a variety of attempts were made to determine the extent of the incursion by searching for serological and clinical evidence of the whereabouts of the virus. At the clinical level, these attempts were hampered by the low virulence of the strain, and at the serological level by the lack of a baseline against which contemporary interpretations could be made. Once it became apparent that neither surveillance tool was likely to produce a rapid result, an infected area was declared on common-sense grounds and emergency vaccination was initiated. The vaccination programme had two objectives, firstly to prevent any further entry across the international border, and secondly to contain and if possible eliminate rinderpest from those districts into which it had already entered. On the few occasions that clinical rinderpest was subsequently found, it was always within this provisional infected area. Emergency vaccination campaigns within the infected area ran from January to the end of March 1997 but were halted by the onset of the long rains. At this time, seromonitoring in two districts showed that viral persistence was still theoretically possible and therefore a second round of emergency vaccination was immediately organized. Further seromonitoring then indicated a large number of villages with population antibody prevalences of over 85%. These populations were considered to have been `immunosterilized'. Although no clinical disease had been observed in them, it was decided to undertake additional vaccination in a group of districts to the south of the infected area. Serosurveillance indicated that rinderpest could have been present in a number of these districts prior to vaccination. Serosurveillance in 1998 suggested that numerous vaccinated animals had probably moved into districts outside the infected and additional vaccination areas, but did not rule out the continued presence of field infection.     

An approximately 15,000-year record of El Nino-driven alluviation in southwestern ecuador

Debris flows have deposited inorganic laminae in an alpine lake that is 75 kilometers east of the Pacific Ocean, in Ecuador. These storm-induced events were dated by radiocarbon, and the age of laminae that are less than 200 years old matches the historic record of El Nino events. From about 15,000 to about 7000 calendar years before the present, the periodicity of clastic deposition is greater than or equal to 15 years; thereafter, there is a progressive increase in frequency to periodicities of 2 to 8.5 years. This is the modern El Nino periodicity, which was established about 5000 calendar years before the present. This may reflect the onset of a steeper zonal sea surface temperature gradient, which was driven by enhanced trade winds.     

Evolution and functional impact of rare coding variation from deep sequencing of human exomes

As a first step toward understanding how rare variants contribute to risk for complex diseases, we sequenced 15,585 human protein-coding genes to an average median depth of 111× in 2440 individuals of European (n = 1351) and African (n = 1088) ancestry. We identified over 500,000 single-nucleotide variants (SNVs), the majority of which were rare (86% with a minor allele frequency less than 0.5%), previously unknown (82%), and population-specific (82%). On average, 2.3% of the 13,595 SNVs each person carried were predicted to affect protein function of ~313 genes per genome, and ~95.7% of SNVs predicted to be functionally important were rare. This excess of rare functional variants is due to the combined effects of explosive, recent accelerated population growth and weak purifying selection. Furthermore, we show that large sample sizes will be required to associate rare variants with complex traits.     

Amplification of mesenchymal stem cells from human bone marrow and orientation to induce MSCs differentiating into endothelial cells in vitro

AIM: Our purpose was to induce MSCs differentiating into endothelial cells (EC) in vitro and to provide the seed cells for study of cardiovascular tissue-engineering. METHODS: MSCs were separated by gradient centrifugation on Percoll (density 1 073 g/L) from human bone marrow (HBM), and incubated for purification and amplification in DMEM (low glucose) with 10% fetal bovine serum (FBS). Then, the MSCs were incubated for orientation differentiated into EC in DMEM (high glucose) with 20% FBS, VEGF (10 μg/L), bFGF (5 μg/L), L-glutamine (2 mmol/L), penicillin (1×105U/L) and streptomycin (100 mg/L) for about 14-21 days and their phenotypic characteristics were analyzed by flow cytometry. Afterwards, the differentiating cells were evaluated by histology and immunohistochemistry. RESULTS: The quantity of MSCs was increased from 5.0×105 in the primary culture to 8.0×1012, or to increase to 1.6×107 times after 15 generations of incubation. The purity of MSCs was above 95% and 98% homogeneous at passages 2 and 3, respectively. About 80%-90% of the differentiating cells from MSCs after 14-21 days were positively stained for Ⅷ factor (vWF) related antigen by immunohistochemistry assay, and Weible-palade corpuscle was also observed by transmission electron microscopy in the cytoplasm. CONCLUSION: MSCs from HBM have the capability of differentiation into ECs in vitro, which may be a potential source of seed cells for fabrication of tissue-engineering heart valve, particularly in children with congenital heart disease.     

加工类型黄瓜品质性状的主成分及聚类分析

对19个加工类型黄瓜品种的7个品质性状进行了主成分和聚类分析.结果表明19个品种分为产量、形态和品质3个主成分因子,其主成分的累计贡献率达89.81%,而且基本上可描述7个品质性状的遗传变异.当类平均距离为1.035时,19个品种被聚为短果和长果2种类型,而当类平均距离为0.942时,19个品种被聚为短果中等品质、短果优质和长果高产3种类型.     

东北三省番茄叶霉病生理小种分化的初步研究

采用国际通用番茄叶霉病鉴别寄主谱，利用苗期人工喷雾接种方法，参照国外Ｎ·Ｈｕｂｂｅｌｉｎｇ氏叶霉病生理小种分化表（１９７１），仿照Ｐ．Ｄａｙ分类方法，对东北三省郊区大棚番茄叶霉病进行鉴定．结果表明．东北三省郊区大棚番茄叶霉病生理小种为小种１，２，３；小种１，３和小种３；而以小种１，２，３为主．     

Design of nondestructive examination system for bridge cables surface defect

Aiming at the drawbacks of the current detecting methods, a nondestructive examination system design for bridge cables based on high speed digital signal processors chip DM642 is presented, and the hardware platform of the system is built. This examination system mainly consists of four parts: the image defaults acquisition part, DM642 hardware platform, creeping part and defaults locating equipment. The designed system is tested on the hardware platform based on digital image processing algorithm. The experimental results show that the detecting system has the advantages of high stability and reliability, real time, mass storage, and nondestructive examination, etc. This system uses high technology and has significant meaning on detecting the current bridge cables health, furthermore, this method can be used in other examination fields.