反义RNA对质粒复制的调控作用

反义RNA的存在最先是在质粒和其它原核附属DNA元件中被证实的.对这些体系深入的研究揭示了原核反义RNA结构和功能的联系,以及正义/反义RNA相互作用的机理.本文着重叙述反义RNA在质粒复制中的作用及其进展.     

移动数据库关键技术的研究与分析

移动数据库是传统分布式数据库系统的扩展,综合了分布式技术、数据库技术和无线通信技术等多门学科领域,能够支持移动用户数据访问要求。移动数据库系统结构主要由固定主机、移动支持站、移动计算机三部分组成。然后主要论述移动数据库的关键技术、数据复制与缓存、数据广播技术、位置相关查询、移动事务处理、移动数据库安全性等技术的研究现状和原理分析。     

Evaluation of current research on stock return predictability

The results of recent replication studies suggest that false positive findings are a big problem in empirical finance. We contribute to this debate by reviewing a sample of articles dealing with the short-term directional forecasting of the prices of stocks, commodities, and currencies. Screening all relevant articles published in 2016 by one of the 96 journals covered by the Social Sciences Citation Index in the category “Business, Finance,” we select only those studies that use easily accessible data of daily or higher frequency. We examine each study in detail, from the selection of the dataset to the interpretation of the results. We also include empirical analyses to illustrate the shortcomings of certain approaches. There are three main findings from our review. First, the number of selected papers is very low, which is surprising even when the strict selection criteria are taken into account. Second, there are hardly any relevant studies that use high-frequency data—despite the hype about financial big data and machine learning. Third, the economic significance of the findings—for example, their usefulness for trading purposes—is questionable. In general, apparently good forecasting performance does not translate into profitability once realistic transaction costs and the effect of data snooping are taken into account. Other typical problems include unsuitable benchmarks, short evaluation periods, and nonoperational trading strategies.     

协同绘图系统中版本合成算法与实现

介绍了协同绘图系统中基于对象的多版本合成策略，设计了基于意愿保证的版本合并算法，该算法使用对象复制策略，充分表达了操作双方的操作意愿．实现了一个基于对象的白板系统OOWB(Object-Oriented White Board)，它可以记录用户的操作历史，可以合并来自同一初始版本的2个版本，实验表明该算法可以有效的保证操作者的操作意愿．最后指出下一步要做的工作。     

一个数据库双向复制的解决方案

描述了几种常用的数据库双向复制模式，并提出了一种更为灵活的复制方案。该方案支持双向复制，能够选择被复制的数据，并且数据可以位于不同类型的数据库服务器上。它易于扩展，具有较高效率和高可用性。     

Fuzzy Logic-Based Secure and Fault Tolerant Job Scheduling in Grid

The uncertainties of grid sites security are main hurdle to make the job scheduling secure, reliable and fault-tolerant. Most existing scheduling algorithms use fixed-number job replications to provide fault tolerant ability and high scheduling success rate, which consume excessive resources or can not provide sufficient fault tolerant functions when grid security conditions change. In this paper a fuzzy-logic-based self-adaptive replication scheduling (FSARS) algorithm is proposed to handle the fuzziness or uncertainties of job replication number which is highly related to trust factors behind grid sites and user jobs. Remote sensing-based soil moisture extraction (RSBSME) workload experiments in real grid environment are performed to evaluate the proposed approach and the results show that high scheduling success rate of up to 95% and less grid resource utilization can be achieved through FSARS. Extensive experiments show that FSARS scales well when user jobs and grid sites increase.     

广义范德—蒙行列式

应用差分学中的结果并运用迭代法和矩阵的初等行变换方法给出了广义范德蒙行列式的值.     

Heterochromatin associated with active versus inactive centromeres of mouse replicates at different times

Summary A subline of mouse L-cells carries a dicentric chromosome in which one centromere always separates prematurely. This centromere is not involved in the dynamics of chromosome migration and is considered inactive. By use of anti-BRdU antibody binding to BRdU-treated chromosomes it is shown that the pericentric constitutive heterochromatin associated with the prematurely separating centromere replicates earlier than its counterpart associated with the active centromere and even before several euchromatic regions in the genome. These results point to a possible mechanism by which dicentric chromosomes segregate equationally.     

基于遗传算法的指数复制方法及其实证研究

指数化投资策略是证券市场主要投资方法和投资策略之一,其核心内容就是构建一个能够完全复制指数走势的跟踪组合,所以研究指数复制方法具有重要的理论意义和巨大的应用价值.对标准的遗传算法进行改造,重新设计了遗传算法的编码方式,适应度函数以及遗传算子,采用最优保存策略加快算法的收敛效率.使用MATLAB语言实现算法,以沪深300作为目标指数,对历史数据进行回测,从实证结果来看,所设计的算法取得不错的跟踪效果.通过对遗传算法和传统的市值抽样法和行业分层抽样法进行对比,发现遗传算法的跟踪效果略优于传统的指数复制方法,遗传算法在指数复制领域有广阔的应用前景.