水样环境DNA分析包括水样采集、DNA提取和分析等流程,已成为监测濒危水生生物种群分布调查的重要手段.为减少在监测目标物种尤其濒危物种中的不确定性,对水环境DNA分析流程的优化至关重要.本研究以川陕哲罗鲑为目标物种,采用滤膜法采集...水样环境DNA分析包括水样采集、DNA提取和分析等流程,已成为监测濒危水生生物种群分布调查的重要手段.为减少在监测目标物种尤其濒危物种中的不确定性,对水环境DNA分析流程的优化至关重要.本研究以川陕哲罗鲑为目标物种,采用滤膜法采集养殖池中的水样,设计了250 mL、500 mL、1 L和2 L等4种水样采集量,分别采用PoweWater DNA Isolation kit和DNeasy Tissue and Blood DNA extraction kit提取水样环境DNA(e DNA),使用物种mtDNAD_loop区特异性引物进行PCR扩增,通过研究滤膜法、水样采集量和水样DNA提取方法对水样e DNA中目标基因检出率的影响,探索适宜的e DNA分析操作方案.结果表明:使用DNeasy Tissue and Blood DNA extraction kit提取的水样DNA中目的基因的检出率为100%,效果明显优于PoweWater DNA Isolation kit(目标基因的检出率为0);目标基因扩增条带的亮度随水样采样量的增加而增加,其中2 L水样目标基因的扩增效果较理想;序列比对结果显示,本试验从水样DNA中成功扩增得到了川陕哲罗鲑mtD NA Dloop区部分序列.表明DNA提取方法和水样采集量对目标物种的检出率有显著的影响,滤膜法、2 L水样采集量、DNeasy Tissue and Blood DNA extraction kit更适宜进行水样的DNA分析,mtD NA D-loop区可作为川陕哲罗鲑识别的特异性分子标记.展开更多
In this paper, we present the modeling and optimization of a Real-Time Protocol（RTP） used in Train Communication Networks（TCN）. In the proposed RTP, message arbitration is represented by a probabilistic model and ...In this paper, we present the modeling and optimization of a Real-Time Protocol（RTP） used in Train Communication Networks（TCN）. In the proposed RTP, message arbitration is represented by a probabilistic model and the number of arbitration checks is minimized by using the probability of device activity. Our optimized protocol is fully compatible with the original standard and can thus be implemented easily. The experimental results demonstrate that the proposed algorithm can reduce the number of checks by about 50%, thus significantly enhancing bandwidth.展开更多
This paper addresses the optimal number of simultaneous data transmissions that maximize the system throughput in an MIMO WLAN. To facilitate simultaneous packet transmissions, both transceivers have to exchange pream...This paper addresses the optimal number of simultaneous data transmissions that maximize the system throughput in an MIMO WLAN. To facilitate simultaneous packet transmissions, both transceivers have to exchange preambles to calculate the channel state information. This exchange is combined with the RTS （request to send）/CTS （clear to send） handshake which is used to contend for the channel in WLANs. This study presents an expression for the optimal number of simultaneous data transmissions under the distributed coordinate function mechanism derived using the Markov chain model, as well as an analytical formula for the optimal system throughput given the length of the contention window and the number of nodes in the network. The analytical results show that the system throughput cannot be enhanced by simply increasing the numoer of simultaneous data transmissions.展开更多
Wide-area systems are becoming a popular infrastructure for long-running applications. Rollback- recovery, as a common technology for fault tolerance and load balance, must meet the challenges of scal- ability and inh...Wide-area systems are becoming a popular infrastructure for long-running applications. Rollback- recovery, as a common technology for fault tolerance and load balance, must meet the challenges of scal- ability and inherent variability in such applications. Most of the rollback-recovery protocols, however, are poor in scalability. Although pessimistic message logging protocols have no such problem, their fault-free overhead sometimes is prohibitive. Aiming at good scalability and acceptable overhead, this paper intro- duces the concept of pessimism grain and presents a coarse-grained pessimistic message-logging scheme. The paper also evaluates the impact of pessimism grain on the performance of the recovery scheme. Ex- perimental results show that pessimism grain is one of the key configuration parameters to reach a desired performance level. In practice, the proper pessimism grain should be selected based on the characteristics of the applications.展开更多
文摘水样环境DNA分析包括水样采集、DNA提取和分析等流程,已成为监测濒危水生生物种群分布调查的重要手段.为减少在监测目标物种尤其濒危物种中的不确定性,对水环境DNA分析流程的优化至关重要.本研究以川陕哲罗鲑为目标物种,采用滤膜法采集养殖池中的水样,设计了250 mL、500 mL、1 L和2 L等4种水样采集量,分别采用PoweWater DNA Isolation kit和DNeasy Tissue and Blood DNA extraction kit提取水样环境DNA(e DNA),使用物种mtDNAD_loop区特异性引物进行PCR扩增,通过研究滤膜法、水样采集量和水样DNA提取方法对水样e DNA中目标基因检出率的影响,探索适宜的e DNA分析操作方案.结果表明:使用DNeasy Tissue and Blood DNA extraction kit提取的水样DNA中目的基因的检出率为100%,效果明显优于PoweWater DNA Isolation kit(目标基因的检出率为0);目标基因扩增条带的亮度随水样采样量的增加而增加,其中2 L水样目标基因的扩增效果较理想;序列比对结果显示,本试验从水样DNA中成功扩增得到了川陕哲罗鲑mtD NA Dloop区部分序列.表明DNA提取方法和水样采集量对目标物种的检出率有显著的影响,滤膜法、2 L水样采集量、DNeasy Tissue and Blood DNA extraction kit更适宜进行水样的DNA分析,mtD NA D-loop区可作为川陕哲罗鲑识别的特异性分子标记.
基金supported by the National Natural Science Foundation of China (Nos. U1201251 and 61402248)the National Key Technologies Research and Development Program of China (No. 2015BAG14B01-02)MIIT IT funds (Research and application of TCN key technologies) of China
文摘In this paper, we present the modeling and optimization of a Real-Time Protocol（RTP） used in Train Communication Networks（TCN）. In the proposed RTP, message arbitration is represented by a probabilistic model and the number of arbitration checks is minimized by using the probability of device activity. Our optimized protocol is fully compatible with the original standard and can thus be implemented easily. The experimental results demonstrate that the proposed algorithm can reduce the number of checks by about 50%, thus significantly enhancing bandwidth.
基金Supported by the National Natural Science Foundation of China(No. 60832008)the joint program between the National Natural Science Foundation of China and the Research Grants Council of Hong Kong (No. 60731160013)
文摘This paper addresses the optimal number of simultaneous data transmissions that maximize the system throughput in an MIMO WLAN. To facilitate simultaneous packet transmissions, both transceivers have to exchange preambles to calculate the channel state information. This exchange is combined with the RTS （request to send）/CTS （clear to send） handshake which is used to contend for the channel in WLANs. This study presents an expression for the optimal number of simultaneous data transmissions under the distributed coordinate function mechanism derived using the Markov chain model, as well as an analytical formula for the optimal system throughput given the length of the contention window and the number of nodes in the network. The analytical results show that the system throughput cannot be enhanced by simply increasing the numoer of simultaneous data transmissions.
文摘以欧洲甜樱桃萨米托品种为研究对象,利用改进的CTAB法提取基因组DNA,并通过单因素多水平梯度试验,筛选了模板、Mg^(2+)、Taq E、dNTPs和随机引物的浓度及用量,建立了欧洲甜樱桃RAPD技术扩增体系.研究结果表明,在25μl反应体系中,各组分最佳的浓度分别为:10×Buffer 2.5μl,2.5mmol·L^(-1)Mg^(2+)2.5μl,Taq E 0.06U·μl^(-1),0.2mmol·L^(-1)dNTPs,0.2μmol·L^(-1)Primer,模板DNA1.2ng·μl^(-1).PCR循环程序为:94℃预变性4min,94℃变性40s,36℃退火45s,72℃延伸1min,共36个循环,最后72℃延伸7min.
基金the National Natural Science Foundation of China (Nos. 60473031, 60673155)the Natural Science Foundation of Hunan (No. 05JJ30116)
文摘Wide-area systems are becoming a popular infrastructure for long-running applications. Rollback- recovery, as a common technology for fault tolerance and load balance, must meet the challenges of scal- ability and inherent variability in such applications. Most of the rollback-recovery protocols, however, are poor in scalability. Although pessimistic message logging protocols have no such problem, their fault-free overhead sometimes is prohibitive. Aiming at good scalability and acceptable overhead, this paper intro- duces the concept of pessimism grain and presents a coarse-grained pessimistic message-logging scheme. The paper also evaluates the impact of pessimism grain on the performance of the recovery scheme. Ex- perimental results show that pessimism grain is one of the key configuration parameters to reach a desired performance level. In practice, the proper pessimism grain should be selected based on the characteristics of the applications.
