In parallel real-time database systems, concurrency control protocols must satisfy time constraints as well as the integrity constraints. The authors present a validation concurrency control(VCC) protocol, which can e...In parallel real-time database systems, concurrency control protocols must satisfy time constraints as well as the integrity constraints. The authors present a validation concurrency control(VCC) protocol, which can enhance the performance of real-time concurrency control mechanism by reducing the number of transactions that might miss their deadlines, and compare the performance of validation concurrency control protocol with that of HP2PL(High priority two phase locking) protocol and OCC-TI-WAIT-50(Optimistic concurrency control-time interval-wait-50) protocol under shared-disk architecture by simulation. The simulation results reveal that the protocol the author presented can effectively reduce the number of transactions restarting which might miss their deadlines and performs better than HP2PL and OCC-TI-WAIT-50. It works well when arrival rate of transaction is lesser than threshold. However, due to resource contention the percentage of missing deadline increases sharply when arrival rate is greater than the threshold.展开更多
[目的]为转基因番茄植株的高通量筛选奠定基础。[方法]利用CTAB法提取番茄叶片总RNA进行Real Time PCR扩增，分析转MI1、2基因的番茄植株表达水平的检测体系。[结果]提取RNA的A260／A280为1．78～1．88，RNA无明显降解。在严谨扩增条件...[目的]为转基因番茄植株的高通量筛选奠定基础。[方法]利用CTAB法提取番茄叶片总RNA进行Real Time PCR扩增，分析转MI1、2基因的番茄植株表达水平的检测体系。[结果]提取RNA的A260／A280为1．78～1．88，RNA无明显降解。在严谨扩增条件下，引物SYBR2的扩增效率高于SYBR1。Mg^2＋的适宜浓度为2．0mg／L。Real Time PCR扩增产物具有良好的特异性，熔解曲线特异峰出现在84．5℃附近，在熔解曲线略低于83℃附近有极微弱的非特异峰。因此在定量反应中信号检测步骤应放在84℃。以4种不同模板分子数条件下扩增曲线Ct值得到的回归方程为Y=-3．78×log（copynumber）＋39．50，相关系数为0．998。[结论]该试验获得的Real Time PCR体系可用于转基因植株表达水平的检测。展开更多
文摘In parallel real-time database systems, concurrency control protocols must satisfy time constraints as well as the integrity constraints. The authors present a validation concurrency control(VCC) protocol, which can enhance the performance of real-time concurrency control mechanism by reducing the number of transactions that might miss their deadlines, and compare the performance of validation concurrency control protocol with that of HP2PL(High priority two phase locking) protocol and OCC-TI-WAIT-50(Optimistic concurrency control-time interval-wait-50) protocol under shared-disk architecture by simulation. The simulation results reveal that the protocol the author presented can effectively reduce the number of transactions restarting which might miss their deadlines and performs better than HP2PL and OCC-TI-WAIT-50. It works well when arrival rate of transaction is lesser than threshold. However, due to resource contention the percentage of missing deadline increases sharply when arrival rate is greater than the threshold.
文摘[目的]为转基因番茄植株的高通量筛选奠定基础。[方法]利用CTAB法提取番茄叶片总RNA进行Real Time PCR扩增，分析转MI1、2基因的番茄植株表达水平的检测体系。[结果]提取RNA的A260／A280为1．78～1．88，RNA无明显降解。在严谨扩增条件下，引物SYBR2的扩增效率高于SYBR1。Mg^2＋的适宜浓度为2．0mg／L。Real Time PCR扩增产物具有良好的特异性，熔解曲线特异峰出现在84．5℃附近，在熔解曲线略低于83℃附近有极微弱的非特异峰。因此在定量反应中信号检测步骤应放在84℃。以4种不同模板分子数条件下扩增曲线Ct值得到的回归方程为Y=-3．78×log（copynumber）＋39．50，相关系数为0．998。[结论]该试验获得的Real Time PCR体系可用于转基因植株表达水平的检测。
