Monitoring the anomalous scattering signal and noise levels in X-ray diffraction of crystals.
Monitoring the anomalous scattering signal and noise levels in X-ray diffraction of crystals.
复制标题
监测晶体 X 射线衍射中的异常散射信号和噪声水平。
DOI：
10.1107/s0907444904000617
复制
发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Wang,Bi-Cheng
中科院分区：
文献类型：
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作者：
Fu,Zheng-Qing;Rose,JohnP;Wang,Bi-Cheng
为了监测异常散射数据集的总体信噪比，提出了一种统计指标Ras。在这种方法中，对称等效反射被合并并分组为中心和非中心子集。中心子集中的反射，理论上应该是相等的，用来估计数据中的噪声水平。这种方法与大多数数据处理程序使用的方法不同，在大多数数据处理程序中，中心反射被合并并平均。通过在数据处理过程中保留中心反射的差异，可以估计噪声水平的内部度量，并用于分析数据中异常信号的质量。指数Ras被定义为合并中心反射的平均比吉沃特差与合并中心反射的比值。对各种数据的测试结果表明，Ras与从数据中确定异常散射子结构的能力具有良好的相关性。在数据收集策略、仪器设置和所使用的数据处理软件方面，Ras也可用于监测数据的质量。Ras分析已经在3DSCALE程序中实现，作为我们实验室正在开发的数据处理程序套件的一部分。
A statistical index Ras is proposed in order to monitor the overall signal-to-noise ratio in an anomalous scattering data set. In this approach, symmetry-equivalent reflections are merged and grouped into centric and non-centric subsets. Reflections in the centric subset, which in theory should be equal, are used to estimate the noise level in the data. This approach differs from that used by most data-processing programs, in which the centric reflections are merged and averaged. By preserving the differences in centric reflections during data processing, an internal measure of the noise level can be estimated and used to analyze the quality of the anomalous signal in the data. An index Ras is defined as the ratio of the average Bijvoet difference of merged acentric reflections to merged centric reflections. Test results on a variety of data show that Ras has good correlation with the capability to determine the anomalous scattering substructure from the data. Ras can also be useful in monitoring the quality of the data in terms of the data-collection strategy, instrument settings and data-processing software used. Ras analysis has been implemented in the program 3DSCALE as part of a data-processing program suite that is under development in our laboratory.