The stress response factor RpoS is required for the natural transformation of Escherichia coli

The natural transformation of Escherichia coli is a novel and recently developed system that has significance for genetic studies and the biological safety of genetic engineering. However, the mechanisms of transformation, including development of competence and DNA uptake, are not thoroughly understood. In this study, we demonstrated the effect of the general stress response regulator RpoS, which has been associated with E. coli transformation, on natural transformation performed in an “open system”. We find that RpoS is required for natural transformation but not to artificial transformation and RpoS mainly affect transformation in the liquid culture prior to plating. In the liquid culture, RpoS over-expression promotes natural transformation in early exponential phase and static incubation accumulates RpoS and promotes transformation to a limited extent. These findings provide detailed understanding of RpoS function on natural transformation.     

The generalized partial transposition criterion for infinite-dimensional quantum systems

The positive partial transposition(PPT)criterion and the realignment criterion constitute two of the most important criteria for detecting entanglement.The generalized partial transposition(GPT)criterion which contains the PPT criterion and the realignment criterion as special cases,provides a necessary condition for a multipartite state to be separable.Here we extend the GPT criterion to the infinitedimensional multipartite(bipartite)case and show that it includes multipartite(bipartite)PPT criterion and multipartite(bipartite)realignment criterion as special cases as well.     

统筹城乡可持续发展动力机制研究——以宜宾市南溪区为例

中国"统筹城乡发展"战略和可持续发展理念的实践取得了丰硕成果,但两者各自成体系、脱离式的研究使得我国统筹城乡发展遭遇瓶颈,也缺乏可持续性,城乡一体化发展也面临困境.特别是统筹城乡可持续发展动力机制框架体系还没有达成共识,进而落实到城市可持续发展建设规划上还存在一定的盲目性.从理论上试图构建统筹城乡可持续发展机制框架体系,然后以可持续发展实验探索区域宜宾市南溪区为例,探索其"两化互动"、"三化联动"支撑下统筹城乡可持续发展机制.通过相关计量方法寻求其驱动力,并科学划分南溪区可持续发展实验分区,提出因地制宜的发展模式.     

关于稠密集的若干探讨

在拓扑空间中探讨了稠密集与无处稠密集这两个概念的几个等价表述形式，给出了一个集合的边界与该集合闭包的边界相等的充分条件。另外，分别在 Hilbert 空间和赋范空间中讨论了稠密集的相关性质和应用。     

Mean Square Average Generalized Consensus of Multi-Agent Systems Under Time-Delays and Stochastic Disturbances

Compared with the traditional consensus problem, this paper deals with the mean square average generalized consensus(MSAGC) of multi-agent systems under fixed directed topology, where all agents are affected by stochastic disturbances. Distributed protocol depending on delayed time information from neighbors is designed. Based on Lyapunov stability theory, together with results from matrix theory and It o s derivation theory, the linear matrix inequalities approach is used to establish sufficient conditions to ensure MSAGC of multi-agent systems. Finally, numerical simulations are provided to illustrate the theoretical results.     

Minimum-Cost Forest for Uncertain Multicast with Delay Constraints

The use of multicast transmission can efficiently reduce the consumption of network resources by jointly serving multiple destinations with a single source node. Currently, many multicast applications impose the constraint wherein multicast flows must be processed by a series of Virtual Network Functions(VNFs) before reaching their destinations. Given a multicast transmission, there are usually multiple server nodes, each of which is able to host all the required VNFs. Thus, the multicast flow should be initially steered to one or a few selected server nodes that act as pseudo sources, and the destinations will then retrieve new flow from any of these pseudo sources.In this paper, we model this kind of multicast as an uncertain multicast with multiple pseudo sources, whose routing structure is usually a forest consisting of multiple isolated trees. We then characterize and construct the Delay-guaranteed Minimum Cost Forest(D-MCF) such that each path from the source to the destination satisfies the end-to-end delay constraint. To tackle this NP-hard problem, we design two efficient methods, the Partition Algorithm(PA) and the Combination Algorithm(CA), to approximate the optimal solution. Theoretical analyses and evaluations indicate that these two methods can generate the desired routing forest for any multicast transfer.Moreover, the PA method achieves a better balance between performance and time consumption than the CA method. The evaluation results show that PA-(Ω+20) can reduce total cost by 49:02% while consuming 12:59% more time, thus significantly outperforming the CA-(Ω+20) method.     

列车运行监控装置文件丢失故障探讨

列车运行监控装置是确保列车安全运行的重要设备,具有监控和记录两大功能,如果记录文件丢失,将给后续的分析工作造成不便,为列车安全运行造成隐患。针对列车运行监控装置记录文件丢失故障问题,分析了故障产生的原因,探讨了解决办法。     

沪深300股指期货与现货的波动关系研究

随着高频数据获取的便利性,采用高频数据研究金融市场的波动越来越普遍。沪深300股指期货市场的迅速发展使得股指期货与现货市场的波动关系研究成为热点。采用MEM模型,对股指期货与现货市场的连续成分(连续样本路径方差)之间和跳跃成分(离散跳跃方差)之间的关系进行研究。结果表明,现货跳跃成分对期货跳跃成分的溢出效应大于期货跳跃成分对现货跳跃成分的溢出效应;现货连续成分对期货连续成分的溢出效应大于期货连续成分对现货连续成分的溢出效应。现货与期货之间的波动溢出效应主要体现在二者的连续成分上。     

CaSnO_3/膨润土复合光催化剂的制备及对亚甲基蓝的光催化降解性能

采用水热合成法制备出CaSnO3/膨润土复合光催化剂,采用XRD、SEM和IR等分析手段对该样品的形貌和结构进行表征,并研究了其对亚甲基蓝水溶液的光催化降解性能.结果表明:负载比例为3%的CaSnO3/膨润土复合光催化剂对亚甲基蓝水溶液的降解效果最好,当催化剂用量为60 mg,反应时间为14 min时,降解率可达98%.