ZnS压致结构相变的第一性原理计算

利用第一性原理计算了闪锌矿结构(ZB)ZnS的压致结构相变.计算结果显示:在压力作用下,ZnS在15.7GPa压力下发生从闪锌矿结构到岩盐矿结构(RS)的转变;在74.4GPa压力下,发生了从岩盐矿结构到正交结构相(Orth)的转变;随着结构的转变,其能带结构和晶胞体积也发生了明显的变化,ZnS的导电性发生了从半导体到导体再到半导体的转变.     

电化教学闭路电视系统前端部分的设计

从实用的角度出发 ,概述了电化教学闭路电视系统前端部分的设计思路 ,从频道设置、线路设计、电平计算、设备选型等方面具体阐述了电化教学闭路电视系统前端设计的基本概念和方法。该系统方案可作为一般学校设计电化教学闭路电视系统时的参考     

Combining evidence from clinical trials in conditional or accelerated approval

Conditional (European Medicines Agency) or accelerated (U.S. Food and Drug Administration) approval of drugs allows earlier access to promising new treatments that address unmet medical needs. Certain post-marketing requirements must typically be met in order to obtain full approval, such as conducting a new post-market clinical trial. We study the applicability of the recently developed harmonic mean ${\chi }^2$-test to this conditional or accelerated approval framework. The proposed approach can be used both to support the design of the post-market trial and the analysis of the combined evidence provided by both trials. Other methods considered are the two-trials rule, Fisher's criterion and Stouffer's method. In contrast to some of the traditional methods, the harmonic mean ${\chi }^2$-test always requires a post-market clinical trial. If the $p$-value from the pre-market clinical trial is $\ll 0.025$, a smaller sample size for the post-market clinical trial is needed than with the two-trials rule. For illustration, we apply the harmonic mean ${\chi }^2$-test to a drug which received conditional (and later full) market licensing by the EMA. A simulation study is conducted to study the operating characteristics of the harmonic mean ${\chi }^2$-test and two-trials rule in more detail. We finally investigate the applicability of these two methods to compute the power at interim of an ongoing post-market trial. These results are expected to aid in the design and assessment of the required post-market studies in terms of the level of evidence required for full approval.     

电算化对会计理论和实务的影响

本文论述了会计电算化在实践工作中所发挥的作用 ,并针对在操作实践过程中产生的舞弊现象提出了相应的防范措施