Chip-Firing and the Critical Group of a Graph

A variant of the chip-firing game on a graph is defined. It is shown that the set of configurations that are stable and recurrent for this game can be given the structure of an abelian group, and that the order of the group is equal to the tree number of the graph. In certain cases the game can be used to illuminate the structure of the group.     

Safety neighbournoods for the invariants of the matrix similarity

We give safety neighbourhoods for the necessary conditions in the change of the Jordan canonical form of a matrix under small perturbations. We also obtain the minimum distance from an n × n complex matrix which has less than k nonconstant invariant factors (2≤ k≤ n) to the set of matrices which have more or equal to k. When k= 2, we get in particular the distance from a nonderogatory matrix to the set of derogatory matrices.     

Simultaneous determination of seven lignans in Justicia procumbens by high performance liquid chromatography–photodiode array detection using relative response factors

A simple and sensitive HPLC coupled with photodiode array (HPLC–PDA) method was developed for simultaneous determination of seven lignans in Justicia procumbens using relative response factors (RRFs). The chromatographic separation was performed on a Shiseido Capcell Pak C₁₈ column (250 × 4.6 mm id, 5 μm), a gradient elution of acetonitrile/water, and a photodiode array detector. The column temperature was maintained at 35°C and the detection wavelength was set at 256 nm. Chinensinaphthol methyl ether was selected as the reference compound for calculating the relative response factors of the lignans. It has shown that the RRFs for lignans are quite similar at 256 nm of detection under different analytical conditions (different columns and HPLC instruments). Using RRFs, not every lignan is needed as a reference standard, making the method ideal for rapid, routine analysis, especially for those laboratories where lignans standards are not readily available. An economic and practicable HPLC method using RRFs was established for the determination of seven lignans in J. procumbens. This method not only can determine multiple indexes in traditional Chinese medicines (TCMs) simultaneously, but also resolve the problem of lacking of chemical standards. It will be a good quality evaluation method and pattern for TCMs.     

Quark-hadron duality in electron-pion scattering

We explore the relationship between exclusive and inclusive electromagnetic scattering from the pion, focusing on the transition region at intermediate Q². Combining Drell-Yan data on the leading twist quark distribution in the pion with a model for the resonance region at large x, we calculate QCD moments of the pion structure function over a range of Q², and quantify the role of higher twist corrections. Using a parameterization of the pion elastic form factor and phenomenological models for the π↦ρ transition form factor, we further test the extent to which local duality may be valid for the pion. Received: 10 February 2003 / Accepted: 12 March 2003 / Published online: 27 May 2003     

Contribution of Quark Structure Term in Nucleon Electric and Magnetic Form Factors

The constituent quarks in the nucleon have always been considered as a point-like particle in the relativistic constituent quark model. However its calculation results of GnE agree poorly with the new experimental data. The electromagnetic structure of light front constituent quarks is considered in this paper. We find that the calculation results have good agreement with the new experimental data of GnE after considering the contribution of the quark structure term. This treatment seems to be able to improve the fit to experimental data of Gep/GMp, /Q2F2p/kpF1p,and Gen/GMn as well.     

农牧民人均收入与影响因素的相关性研究

本文应用多元统计分析方法 ,把影响农牧民人均收入增长的主要指标纳入数学模型 ,研究农牧民人均收入与影响因素之间的关系 .分析内蒙古农牧民人均纯收入增长缓慢、乏力的原因 ,寻找农牧民人均纯收入的持续稳定增长的途径     

最优回归设计在落叶松遗传转化体系主导因子优化筛选试验中的应用

阐述了 3 1 1 -A最优回归设计的数学模型 ,并利用此模型对落叶松遗传转化体系中主导因子 2 .4-D、BA、KT的浓度水平进行了优化筛选 ,获得了最佳水平组合及最佳胚性愈伤组织发生量 .结果表明 ,最优回归设计是一种科学、合理、实用的优化培养基的方法 .     

基于主成分因素法的企业绩效比较方法

本通过比较多种企业财务绩效因素，建立了基于主成分因素法的企业绩效比较模型，并通过对国外上市的信息安全公司进行比较实证检验，验证了该预测模型在实际市场上与企业的市场地位是相符的。