A Note on Sampling from Combinations of Distributions

A rejection technique is described for sampling from a combinationof distributions with negative weights for some of the components.     

Application of a Direct Stiffness Method to Wave Propagation in Multiphase Poroelastic Media

In this paper, it is demonstrated how a direct stiffness method for wavepropagation in multilayered saturated poroelastic media, based on integraltransform techniques, can be modified to account for a small amount of gasin the pores. Unsaturated media with small gas fractions can be treatedusing Smeulders extension of Biots poroelastic theory. The effect of thepresence of gas bubbles on the fluid bulk modulus and the dispersioncharacteristics of a water-saturated sand of Mol is demonstrated. Thedirect stiffness method is illustrated with a numerical example wheretransient wave propagation in a dry, saturated and unsaturated halfspaceis considered.     

UH和UH_2分子的结构与势能函数

用相对论有效原子实势 (RECP)和密度泛函 (B3LYP SDD)方法研究了UH ,UH2 基态和低激发态的结构和势能函数 ,导出了分子的光谱数据 .结果表明 ,UH和UH2 的基电子状态分别为X4 Π和X3A2 ,离解能分别为 2 .886eV和5 .2 4 9eV ,UH2 具有C2v对称性 ,得到了UH和UH2 的几个不同的低激发态的结构与光谱数据 .应用多体项展式理论以及数字拟合方法 ,计算得到了UH分子和基态UH2 三原子分子的分析势能函数 ,该函数正确反映了UH和UH2分子的结构特征 ,可用于研究UHH的微观反应动力学 .     

GLOBAL ANALYSIS OF THE TIME-RESOL VED FLUORESCENCE OF α-CHYMOTRYPSINOGEN A AND α-CHYMOTRYPSIN POWDERS AS A FUNCTION OF HYDRATION

The time-resolved tryptophyl fluorescence of alpha-chymotrypsin A and alpha-chymotrypsin in the crystalline state and in buffer solution at room temperature was analyzed globally. Triple-exponential decay functions are necessary to adequately describe the tryptophyl fluorescence decay surfaces of the protein powders as a function of hydration and in solution. The fluorescence lifetimes of alpha-chymotrypsinogen A (tau 1 = 0.32, tau 2 = 1.30 ns, tau 3 = 3.98 ns) and alpha-chymotrypsin(tau 1 = 0.66 n s, tau 2 = 2.26 ns, tau 3 = 5.40 ns) are constant over the entire hydration range. The spectral positions of the decay-associated spectra of the hydrated powders do not shift as a function of hydration. This indicates that the structures of the zymogen and the active enzyme are unaffected by hydration. The lifetimes of alpha-chymotrypsinogen A in phosphate buffer pH 7.4 are tau 1 = 0.37 ns, tau 2 = 1.17 ns and tau 3 = 3.44 ns while the respective values of alpha-chymotrypsin are tau 1 = 0.47 ns, tau 2 = 1.40 and tau 1 = 3.89 ns.     

Design of sparse matrix representations for the propagator used in the BPM and directional wave field decomposition

Directional wave field decomposition can be accomplished with the aid of pseudo-differential operators. A fast numerical scheme requires sparse matrix representations of these operators. This paper focuses on designing sparse matrices for the propagator while keeping the accuracy high at the cost of ignoring critical-angle phenomena. The matrix representation follows from a rational approximation for the square root operator and the derivatives. The parameterization thus introduced lends itself to an overall optimization procedure that minimizes the errors for a chosen discretization rate. As such, the approach leads to an accurate propagator up to the (local) critical angle on a coarse numerical grid. This revised version was published online in November 2006 with corrections to the Cover Date.     

[H_2N(C_2H_4)_2NH_2]_4(H_3O)[PMo_2~VMo_6~(VI)V_4~(IV)O_(40)(V~(IV)O)_2]·H_2O: A New Highly Reduced, Bicapped Pseudo-Keggin Vanadylpolymolybdophosphate

Ｐｏｌｙｏｘｏｍｅｔａｌａｔｅｓ (ＰＯＭｓ)ｃｏｎｔａｉｎｉｎｇＫｅｇｇｉｎｍｏｉ ｅｔｉｅｓｈａｖｅｂｅｅｎｒｅｃｅｉｖｉｎｇｅｘｔｅｎｓｉｖｅａｔｔｅｎｔｉｏｎｉｎｒｅｃｅｎｔｙｅａｒｓｏｗｉｎｇｔｏｔｈｅｉｒｇｒｅａｔｆｕｎｄａｍｅｎｔａｌａｎｄｐｒａｃｔｉｃａｌｉｎｔｅｒ ｅｓｔ .1Ｅｓｐｅｃｉａｌｌｙｔｈｅｕｎｕｓｕａｌｅｌｅｃｔｒｏｎｉｃｐｒｏｐｅｒｔｙ (ｈｉｇｈｎｅｇａｔｉｖｅｃｈａｒｇｅｓ) ,ｏｎｅｏｆｔｈｅｍｏｓｔｉｍｐｏｒｔａｎｔｐｒｏｐｅｒｔｉｅｓｏｆＰＯＭｓ ,ｈａｓｐｏｔｅｎ…