汉江洪水频率计算不确定性分析(Ⅱ):统计过程不确定性

使用NUSAP方法对洪水频率分析中的两种流量序列选取方法进行不确定性评价,然后对于选用的4种分布函数,分别使用矩法和极大似然法进行参数估计,针对不同的参数估计方法以及分布函数,应用NUSAP方法结合曲线拟合误差综合评价其中的不确定性.结果表明,超阈值方法是一种较为科学的时间序列选取方法,广义柏拉图分布和PⅢ分布对流量序列的拟合结果较好.NUSAP方法对上述分布函数和各种参数估计方法的评价结果更直观、更合理,是其在洪水频率分析领域应用的一个良好开端.     

Mitochondrial aspartyl-tRNA synthetase deficiency causes leukoencephalopathy with brain stem and spinal cord involvement and lactate elevation

Leukoencephalopathy with brain stem and spinal cord involvement and lactate elevation (LBSL) has recently been defined based on a highly characteristic constellation of abnormalities observed by magnetic resonance imaging and spectroscopy. LBSL is an autosomal recessive disease, most often manifesting in early childhood. Affected individuals develop slowly progressive cerebellar ataxia, spasticity and dorsal column dysfunction, sometimes with a mild cognitive deficit or decline. We performed linkage mapping with microsatellite markers in LBSL families and found a candidate region on chromosome 1, which we narrowed by means of shared haplotypes. Sequencing of genes in this candidate region uncovered mutations in DARS2, which encodes mitochondrial aspartyl-tRNA synthetase, in affected individuals from all 30 families. Enzyme activities of mutant proteins were decreased. We were surprised to find that activities of mitochondrial complexes from fibroblasts and lymphoblasts derived from affected individuals were normal, as determined by different assays.     

汉江洪水频率计算不确定性分析(Ⅰ):流量测量阶段的不确定性

洪水频率分析中的不确定性是影响设计洪水精度的主要因素,为了更全面的评价洪水频率分析中的不确定性,提高计算结果精度,使用NUSAP方法对流量测量阶段的不确定性进行了评价.首先,从总体上阐述了NUSAP方法的原理和评价机制,提出了适用于洪水频率分析领域的Ped igree矩阵,然后结合该矩阵将NUSAP方法应用于流量测量不确定性评价.结果证明NUSAP方法在对流量测量进行不确定性评价时是有效的,可以考虑进一步应用于整个洪水频率分析阶段.