DNA装配中的纠错

DNA装配问题是指把各个读出序列（reads）拼接成一条完整的DNA链，即确定原DNA链的核苷酸“A，T，C，G”的排列顺序。实验中，由于各种原因测出的读出片段序列与DNA链的实际结果会有误差，这些误差会影响到用于装配的算法的性能，因此需要对测出的读出序列进行纠错。现有的算法如： ECINDEL和SRCorr都能够对实验数据进行纠错。但是它们都是根据某个读出序列出现的次数来判断它的正确性。这类算法首先选择参数k和M，若读出序列所有长度为k的子串出现的次数均大于M次，则它为正确的读出序列，即确实为原DNA链的子串。同时，还可以利用这些长度为k的子串来对原来的读出序列片段进行纠错。 然而，在这些算法中，M的选择要么是一个固定值，要么是随机的，使得这些算法在纠错问题上的表现并不稳定。 本文我们计算长度为k的子串出现M次时，它的真阳性（确实为原DNA链的一部分）的概率以及假阳性和假阴性的概率。根据计算结果，我们可以选择一个最优的M值使得最后选取的子串的错误最少，即假阳性的子串与假阴性的子串的数量之和最少。我们在模拟数据和实际数据上进行了验证，与之前的纠错算法ECINDEL，SRCorr相比，我们的算法总的错误率降低了77.6％和65.1％。

有限构模器的扩展及其在形式化方法中的应用

规约在软件开发和验证中占有重要地位 .对于以一阶逻辑为基础的规约 ,可以利用有限模型构造技术对其执行并测试 .文中研究规约中某些特性的处理 ,包括存在量词以及二元关系的传递闭包 .对已有的一个构模工具进行扩充 ,发现了文献中的若干错误

无线Web访问的缓存和预取机制

缓存和预取在提高无线环境下的Web访问性能方面发挥着重要作用。文章研究针对无线局域网的Web缓存和预取机制,分别基于数据挖掘和信息论提出了采用序列挖掘和延迟更新的预测算法,设计了上下文感知的预取算法和获益驱动的缓存替换机制,上述算法已在Web缓存系统OnceEasyCache中实现。性能评估实验结果表明,上述算法的集成能有效地提高缓存命中率和延迟节省率。

印刷线路板废弃物的热解与动力学实验研究

分别应用管式炉反应器和热重分析手段对印刷线路板废弃物的热解行为和热解动力学进行了实验研究。在管式炉中，研究不同的热解温度：700～950℃，对产物分布和气体成分分布的影响。实验结果表明：PCB热解气体的主要成分是H2和CO2，气体的热值较低，仅为2.09～5.41MJ/m^3，PCB不适合以气体产物为目标的能源利用方式。应用Friedman方法对PCB的热解动力学进行了研究，求得PCB的热解动力学参数分别是：表观活化能190.92kJ/mol，反应级数5.97，指前因子lnA47.14min^-1。

受迫内流气体发生的理论及实验关联

受迫内流气体发生的理论及实验关联郭开华，陈阵，舒碧芬，蒙宗信（中国科学院广州能源研究所热泵及空调制冷技术研究中心广州510070）关键词气体发生，多相流，混合物，传热传质1引言在吸收式能量转换系统（如吸收人热泵、制冷机、吸收压缩复合式热泵、卡林纳动力...

Pool boiling heat transfer of ultra-light copper foam with open cells

High speed visualizations and thermal performance studies of pool boiling heat transfer on copper foam covers were performed at atmospheric pressure, with the heating surface area of 12.0 mm by 12.0 mm, using acetone as the working fluid. The foam covers have ppi (pores per inch) from 30 to 90, cover thickness from 2.0 to 5.0 mm, and porosity of 0.88 and 0.95. The surface superheats are from -20 to 190 K, and the heat fluxes reach 140 W/cm(2). The 30 and 60 ppi foam covers show the periodic single bubble generation and departure pattern at low surface superheats. With continuous increases in surface superheats, they show the periodic bubble coalescence and/or re-coalescence pattern. Cage bubbles were observed to be those with liquid filled inside and vented to the pool liquid. For the 90 ppi foam covers, the bubble coalescence takes place at low surface superheats. At moderate or large surface superheats, vapor fragments continuously escape to the pool liquid. Boiling curves of copper foams show three distinct regions. Region I and II are those of natural convection heat transfer, and nucleate boiling heat transfer for all the foam covers. Region III is that of either a resistance to vapor release for the 30 and 60 ppi foam covers, or a capillary-assist liquid flow towards foam cells for the 90 ppi foam covers. The value of ppi has an important effect on the thermal performance. Boiling curves are crossed between the high and low ppi foam covers. Low ppi foams have better thermal performance at low surface superheats, but high ppi foams have better one at moderate or large surface superheats and extend the operation range of surface superheats. The effects of other factors such as pool liquid temperature, foam cover thickness on the thermal performance are also discussed.

Low potential detection of glutamate based on the electrocatalytic oxidation of NADH at thionine/single-walled carbon nanotubes composite modified electrode

A glutamate biosensor based on the electrocatalytic oxidation of reduced nicotinamide adenine dinucleotide (NADH), which was generated by the enzymatic reaction, was developed via employing a single-walled carbon nanotubes/thionine (Th-SWNTs) nanocomposite as a mediator and an enzyme immobilization matrix. The biosensor, which was fabricated by immobilizing glutamate dehydrogenase (GIDH) on the surface of Th-SWNTs, exhibited a rapid response (ca. 5 s), a low detection limit (0.1 mu M), a wide and useful linear range (0.5-400 mu M), high sensitivity (137.3 +/- 15.7) mu A mM(-1) cm(-2), higher biological affinity, as well as good stability and repeatability. In addition, the common interfering species, such as ascorbic acid, uric acid, and 4-acetamidophenol, did not cause any interference due to the use of a low operating potential (190 mV vs. NHE). The biosensor can be used to quantify the concentration of glutamate in the physiological level. The Th-SWNTs system represents a simple and effective approach to the integration of dehydrogenase and electrodes, which can provide analytical access to a large group of enzymes for wide range of bioelectrochemical applications including biosensors and biofuel cells.