THE UNIQUENESS AND CONTINUOUS DEPENDENCE FOR CHARACTERISTIC CAUCHY PROBLEM OF PARTIAL DIFFERENTIAL EQUATIONS

ＴＨＥＵＮＩＱＵＥＮＥＳＳＡＮＤＣＯＮＴＩＮＵＯＵＳＤＥＰＥＮＤＥＮＣＥＦＯＲＣＨＡＲＡＣＴＥＲＩＳＴＩＣＣＡＵＣＨＹＰＲＯＢＬＥＭＯＦＰＡＲＴＩＡＬＤＩＦＦＥＲＥＮＴＩＡＬＥＱＵＡＴＩＯＮＳＬｕａｎＷｅｎｇｕｉ（栾文贵）（ＣｏｍｐｕｔｉｎｇＣｅｎｔ...     

关于SL(2,R)上主级数表示、离散级数表示的矩阵系数的平方可积性

人们知道SU（２）的不可约酉表示的矩阵元是相互正交且平方可积的（Ｐｅｔｅｒ Ｗｅｙｌ定理）． 对于SU（２，R）的主级数表示和离散级数表示的矩阵系数是否有类似的结果？在该文中，作者部分给出了这个问题的肯定回答，即关于主级数表示的矩阵系数是准平方可积的，关于离散级数表示 的矩阵系数是平方可积的． 此外，他们还得到了离散级数表示（除狀＝±１外）在子空间′狀上的矩阵系数是绝对可积的．     

Analysis of pesticide residues in fruit and vegetables by matrix solid phase dispersion (MSPD) and different gas chromatography element-selective detectors

Summary A comparison between different element selective detectors for the determination of organophosphorus and organochlorine pesticide residues, from fruit and vegetables, was performed by capillary GC with electron capture detector (ECD), nitrogen phosphorus detector (NPD), flame photometric detector (FPD) in the sulphur and phosphorus modes, and mass spectrometry detector (MSD) in selected ion monitoring (SIM) mode. Pesticides were extracted from the different foodstuffs by Matrix Solid Phase Dispersion (MSPD). Recoveries of 41–108 % with relative standard deviation of 2–14 % in the concentration range 0.5–10 μg L⁻¹ were obtained in oranges, lemons, grapefruit, pears, plums, lettuces and tomatoes. The results demonstrated that the extracts of all the samples can be analyzed by the detectors used since no interfering co-extracted compounds were detected.     

Modular Automorphisms of Upper Triangular Matrices over a Commutative Ring Preserving Rank One

Ｍｏｄｕｌａｒ　Ａｕｔｏｍｏｒｐｈｉｓｍｓ　ｏｆ　Ｕｐｐｅｒ　Ｔｒｉａｎｇｕｌａｒ　Ｍａｔｒｉｃｅｓ　ｏｖｅｒ　ａ　Ｃｏｍｍｕｔａｔｉｖｅ　Ｒｉｎｇ　Ｐｒｅｓｅｒｖｉｎｇ　Ｒａｎｋ　ＯｎｅＣａｏＣｈｏｎｇｇｕａｎｇ（曹重光）（Ｄｅｐａｒｔｍｅｎｔｏｆ...     

Approximate factorizations with modified S/P consistently ordered M-factors

Preconditioned iterative methods are widely used to solve linear systems such as those arising from the finite element formulation of boundary value problems and approximate factorizations are widely used as preconditioners. The ordering of the unknowns is therefore an important issue because it has a strong influence on the convergence behaviour of the iteration method while it is also a decisive aspect for their parallel implementation. Consistent orderings are attractive for parallel implementations and it has been shown that some subclasses of these orderings also enhance the convergence behaviour of the associated iteration methods. This has in particular been shown for the so-called S/P consistent orderings. A wider definition of this class of orderings has recently been proposed and we investigate here how approximate factorizations should be implemented when using such more general orderings (still called S/P consistent) in order to keep their expected high convergence properties. A simple practical conclusion is suggested, supported by both theoretical and numerical arguments.     

Upper and lower bounds for the arithmetic-geometric-harmonic means of positive definite matrices

New upper and lower bounds are given for the arithmetic,geometric and harmonic means of a set of positive definite matrices     

On a Compression of Normal Matrix Polynomials

In this article, we study a compression of normal matrices and matrix polynomials with respect to a given vector and its orthogonal complement. The numerical range of this compression satisfies special boundary properties, which are investigated in detail. The characteristic polynomial of the compression is also considered.     

石墨炉原子吸收光谱法测定饮料中的锗及基体干扰的研究

本实验以硝酸镍为基体改进剂，用塞曼石墨炉原子吸收法测定样品中的微量锗，研究了溶液介质与共存元素对测定的影响。方法简便，准确快速，灵敏度高。     

平台石墨炉原子吸收法测定高温镍基合金中铋

本文用１ｍｇ／ｍＬ镍和０．２ｍｇ／ｍＬ钯作混合基体改进剂，提高了测定铋的灰化温度和抗干扰能力，且灵敏度几乎不变。可不经分离样品基体，直接用平台石墨炉原子吸收法测定高温镍基合金中铋。方法特征量为１８ｐｇ，检出限为０．０８１μｇ／ｇ。对含０．３－０．７μｇ／ｇ铋的镍基样品测定，相对标准偏差为３．０％－５．９％，回收率在８５％－１１９％之间。     

Determination of microcystins in natural blooms and cyanobacterial strain cultures by matrix solid-phase dispersion and liquid chromatography–mass spectrometry

An analytical procedure based on matrix solid-phase dispersion (MSPD) and liquid chromatography–mass spectrometry (LC-MS) was developed for determining three microcystins (MCs) in natural water blooms and cyanobacteria strain cultures. The procedure involves sample homogenization with C₁₈, washed with dichloromethane to eliminate interfering compounds, and elution with acidic methanol. Results were compared to those achieved by using an organic solvent standard method. Mean recoveries of MCs with MSPD were 85–92% with intra-day relative standard deviation (RSDs) of 9–19%, whereas organic solvent extraction resulted in recovery rates of 92–105% with intra-day RSDs ranging from 8 to 18%. Limits of quantification (LOQs) were 1 g g^–1 dry weight for the MCs either by MSPD or organic solvent extraction. The two analytical methods tested were specific and sensitive to the extraction of MCs and were applied to the detection of MCs in water blooms and culture strains. The concentration of MCs varied from 7 to 3,330 g g^–1 of lyophilized cells with MC-LR always showing the highest concentration. MCs levels were higher in culture strains than in water blooms, except for MC-LR, whose concentration in blooms was slightly superior to that determined in culture strains.