SWIFT伽玛暴的谱延迟距离指示器

早期研究发现,BASTE长暴的相对谱延迟RSL是一个有用的宇宙距离指示器。本文从SWIFT卫星数据中,挑选10个单脉冲长伽玛暴(T90>2.6)作为样本,对样本进行降噪和去除背景,用交叉相关函数分析1,3能道的谱延迟,通过拟合研究各脉冲参数Asymmetry,Fm,Fp,tm,FWHM,τ31和相对谱延迟的关系,发现相对谱延迟和红移具有很好的相关性,这充分表明SWIFT长暴的相对谱延迟仍然是一个很好的红移指示器。     

三维Franck-Condon因子的代数表示及其应用

基于多振动模混合下任意维Franck-Condon重叠积分封闭表示,推导出三维四振动模Franck-Condon重叠积分的解析表示式;凭借厄米多项式的求和形式,给出计算三维四振动模Franck-Condon因子的一般代数公式,且应用于研究甲醛分子光电子能谱的强度分布及振动结构.对于D2CO+(~A2B1)-D2CO(~X1A1)离子化过程,通过Franck-Condon因子计算,得到光电子能谱的谱线相对强度,理论上计算出光电子能谱图,且与实验光电子能谱符合的较好.     

Φ形图簇的伴随分解定理及其补图的色等价性

本文运用图的伴随多项式的性质,讨论了图簇ΦS（（k n＋1）δ,nδ）∪2kSδ的伴随多项式的因式分解定理,进而证明了它们的补图的色等价性.     

镶嵌铜多孔铝膜透射光谱曲线中干涉现象的研究

用阳极氧化的方法制备了阳极氧化铝膜,向其孔中镀入了铜,然后利用UV-3101PC型分光光度计进行了透射光谱测试.实验结果表明,在其可见光和近红外光波段的透射曲线中有明显的振荡现象.利用Maxwell-Garnett理论,分析了这种振荡现象产生的原因,从理论上说明了这种振荡现象是由薄膜干涉引起的,最后提出了用冷杉胶将多孔铝膜胶合在两BaF2窗口的方法,有效消除了透射光谱曲线中的干涉效应.     

Zakharov方程组半离散Fourier谱格式的稳定性

为研究等离子体物理中Zakharov方程组数值方法解的适定性,利用Fourier谱方法,在有限时间段[0,T]内,分析Fourier谱格式解的存在性和收敛性,研究半离散Fourier谱格式的稳定性。首先证明了误差eM的L2模,其次证明了eM和ηM的能量模,最后利用Grnwall不等式,借助稳定性的分析方法,证明了Zakharov方程组Fourier谱格式解的稳定性,从而得到了方程组在空间方向上近似解的稳定性结论。     

Wiener-Hopf factorization of a class of matrix functions and Corona theorem

By using Riemann-Hilbert method and Corona theorem, Wiener-Hopf factorization for a class of matrix functions is studied. Under appropriate assumption, a sufficient and necessary condition for the existence of the matrix function admitting canonical factorization is obtained and the solution to a class of non-linear Riemann-Hilbert problem is also given. Furthermore, by means of non-standard Corona theorem partial estimation of the general factorization can be obtained. Foundation item: Supported by the National Natural Science Foundation of China(10471107) and the Specialized Research Fund for the Doctoral Program of Higher Education of China (20060486001)     

Sequence analysis of the Microcystis aeruginosa FACHB-912 phytochrome gene supports positive selection in cyanobacteria

The phytochrome gene from Microcystis aeruginosa FACHB-912,isolated from algal blooms in Taihu Lake in China,was sequenced and found to code for a wavelength transition light receptor protein.The gene was composed of five distinct domains:a PAS fold domain,a GAF domain,a phytochrome domain,a His Kinase A(phosphoacceptor) domain,and a histidine kinase domain.Red-absorbing phytochrome,far-red-absorbing phytochrome,and photoconversion kinetics were monitored via the spectral characteristics of the protein.To detect positive selection,homologous sequences from cyanobacterium phytochrome genes were obtained from GenBank.Potential selective pressure was identified by phylogenetic analysis with maximum likelihood analyses.The frequency of the phytochrome gene being subjected to selective constraints suggests that positive selection is a potentially important mechanism that promotes the evolution of the cyanobacteria phytochrome gene.The sites identified in this study provide targets for further research on the structural-functional role of these residues,and on the correlation with the mechanism of algal blooms.     

Regularization strategy for the Cauchy problem of Laplace’s equation from the viewpoint of regularization theory

Within the framework of the regularization theory, a spectral regularization method is introduced and analyzed. The convergence estimate under an appropriate choice of regularization parameter is obtained. A numerical implementation is described. Numerical examples show that the proposed method is effective and stable.     

某些随机信号模型功率谱密度的极值研究

在设计某些随机信号模型的数字滤波器时,希望它在某固定频率λ_θ处有最大功率谱密度,同时又希望总功率最小.本文给出了这时参数应满足的条件,并研究了有关功率谱密度的极值问题.