科技爱好者周刊（第 388 期）：测试是新的护城河

The durations of 388 gamma-ray bursts, detected by the Swift satellite, are studied statistically in order to search for their subgroups. Then the results are compared with the results obtained earlier from the BATSE database. The standard chi^2 test is used. Similarly to the BATSE database, the short and long subgroups are well detected also in the Swift data. Also the intermediate subgroup is seen in the Swift database. The whole sample of 388 GRBs gives a support for three subgroups.

土地测量工作作为土地管理工作的前提,是一项对技术要求很高的工作,在土地测量过程中为了保证测量数据的准确性,对于具体的测量过程中出现的问题要及时解决,重视测量过程中方法的使用,对不同测量环境中需要注意的问题有较高的重视,保证整个测量工作的顺利进行。

We present a comment on a recent letter by B. Edwards, N.W. Ashcroft, Nature 388 (1997) 652, in which the dielectric instabilty of the phase III of the solid molecular hydrogen system is suggested on the basis of electrostatics.

New families of matroids are constructed in this note. These new fami- lies are derived from the concept of linearly independent set family (LISF) introduced by Eicker and Ewald [Linear Algebra and its Applications 388 (2004) 173-191]. The proposed construction generalizes in a natural way the well known class of vectorial matroids over a field.