A block SPP algorithm for multidimensional tridiagonal equations with optimal message vector length

A parallel strategy for solving multidimensional tridiagonal equations is investigated in this paper. We present in detail an improved version of single parallel partition (SPP) algorithm in conjunction with message vectorization, which aggregates several communication messages into one to reduce the communication cost. We show the resulting block SPP can achieve good speedup for a wide range of message vector length (MVL), especially when the number of grid points in the divided direction is large. Instead of only using the largest possible MVL, we adopt numerical tests and modeling analysis to determine an optimal MVL so that significant improvement in speedup can be obtained.

固氮蓝藻（Nostoc spp.）基因组文库的构建及固氮酶结构基因克隆

分离自新疆干旱荒漠地区的固氮蓝藻Nostoc spp.被证明具有较高的乙炔还原活性和特异抗逆性。为了保存Nostoc spp.的优良遗传性状和今后研究所需，我们以EMBL4噬菌体为载体，以Sau3AI部分酶解的15-22kb DNA片段为供体，构建了Nostoc spp.的基因组文库。以克氏肺炎杆菌和Anabaena sp. PCC7120的nifHDK DNA片段为探针，通过三轮噬菌斑原位杂交，成功地从基因文库中分离到了六个重组噬菌体阳性克隆。Southern杂交验证插入片段含有Nostoc spp.的固氮酶结构基因序列，并对其限制酶切图谱作了初步分析。