Overexpression in Catharanthus roseus hairy roots of a truncated hamster 3-hydroxy-3-methylglutaryl-CoA reductase gene

Catharanthus roseus (L.) G. Don hairy roots harboring hamster 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) (EC 1.1.1.88) cDNA without membrane-binding domain were evaluated by quantifying the levels of sterols and some indol-alkaloids. Clone 236, with the highest hybridization signal, had the lowest soluble and microsomal HMGR activity and produced more ajmalicine and catharanthine than the control but had reduced campesterol concentration. Clone 19, with low hybridization signal, had high soluble HMGR activity and produced high levels of campesterol and five to seven times more serpentine than the control but a low level of ajmalicine and no accumulation of catharanthine. These results suggest a possible role for HMGR in indole alkaloid biosynthesis and a possible cosuppression of both the endogenous and foreign HMGR genes in clone 236.     

Complex Zeros of Algebraic Polynomial with Non-Zero Mean Random Coefficients

In this paper we obtain a formula for the average density of the distribution of complex zeros of an algebraic polynomial with random coefficients. The coefficients are assumed independent identical normally distributed random variables with mean and variance ². The value of the average density for the case of =0 and ²=1 was obtained previously. Some limits of the distribution of the complex zeros are provided using the presented formula.     

On random algebraic polynomials

This paper provides asymptotic estimates for the expected number of real zeros and -level crossings of a random algebraic polynomial of the form , where are independent standard normal random variables and is a constant independent of . It is shown that these asymptotic estimates are much greater than those for algebraic polynomials of the form .

     

On the Location of Roots of Independence Polynomials

The independence polynomial of a graph G is the function i(G, x) = _k0 i _k x ^k, where i _k is the number of independent sets of vertices in G of cardinality k. We prove that real roots of independence polynomials are dense in (–, 0], while complex roots are dense in , even when restricting to well covered or comparability graphs. Throughout, we exploit the fact that independence polynomials are essentially closed under graph composition.     

On the Computation of Square Roots in Finite Fields

In this paper, two improvements for computing square roots in finite fields are presented. Firstly, we give a simple extension of a method by O. Atkin, which requires two exponentiations in FM _q , when q9 mod 16. Our second method gives a major improvement to the Cipolla–Lehmer algorithm, which is both easier to implement and also much faster. While our method is independent of the power of 2 in q–1, its expected running time is equivalent to 1.33 as many multiplications as exponentiation via square and multiply. Several numerical examples are given that show the speed-up of the proposed methods, compared to the routines employed by Mathematica, Maple, respectively Magma.     

Testing for Unit Roots in a Nearly Nonstationary Spatial Autoregressive Process

The limiting distribution of the normalized periodogram ordinate is used to test for unit roots in the first-order autoregressive model _st= _s-1,t+_s,t-1- _s-1,t-1+_st. Moreover, for the sequence _n = e ^c/n , _n = e ^d/n of local Pitman-type alternatives, the limiting distribution of the normalized periodogram ordinate is shown to be a linear combination of two independent chi-square random variables whose coefficients depend on c and d. This result is used to tabulate the asymptotic power of a test for various values of c and d. A comparison is made between the periodogram test and a spatial domain test.     

Bootstrap tests for unit roots in seasonal autoregressive models

This paper proposes bootstrap tests for the presence of unit roots in a seasonal autoregressive model. The asymptotic validity of the proposed bootstrap scheme is established, and Monte Carlo experiments are used to investigate the small-sample performance of the tests.     

Finite Hopf Algebras and Bidifferential Structures

In this Letter we show the existence of bidifferential structures on finite Hopf algebras, which arise from quantum groups at roots of unity.     

保留指数结合准确质量测定对鱼腥草挥发性成分的定性分析

采用顶空-气相色谱-四极质谱法和顶空-气相色谱-飞行时间质谱法对鱼腥草挥发性成分进行检测,运用保留指数结合准确质量测定,分别从鱼腥草茎和叶中鉴定出49、39种挥发性组分,并采用峰面积归一化法测定各组分的相对含量。鱼腥草茎和叶中的挥发性成分差别较大。鱼腥草茎以α-蒎烯(12.24%)、β-蒎烯(22.42%)、月桂烯(11.98%)、乙酸冰片酯(10.97%)、甲基正壬酮(10.83%)为主要成分,而鱼腥草叶则以月桂烯(39.48%)、(Z)-β-罗勒烯(26.52%)、癸醛(10.35%)、桧烯(4.43%)、甲基正壬酮(2.44%)为主。结合保留指数和准确质量测定能显著提高质谱定性的准确性,有利于解决质谱检索时定性不确定的问题。