基于估计均方差的统计量Sp的修正变量选择法用于持久性有机污染物毒性研究

提出并详细说明基于估计均方差的统计量Sp的修正变量选择(MVSSp)方法. 采用分子电性距离矢量(MEDV)及其二次项表征多氯二苯并呋喃(PCDFs), 多氯二苯并二噁英(PCDDs)和多氯联苯(PCBs)三种持久性有机污染物异构体分子结构, 结合MVSSp方法选择适当的描述子, 建立了三种持久性有机污染物分别对芳烃受体(AhR)亲合性, 芳香羟化酶(AHH), 7-乙氧基异吩唑酮-脱乙基酶(EROD)诱导作用的定量结构活性相关(QSAR)模型, 模型的质量优于文献或相当, 讨论了这些实验毒性与分子结构关系. 这对研究和预测这些持久性污染物的毒性具有一定的指导意义.     

Gumbel分布最大吸引场的次序统计量的精致渐近性

得到一类Gumbel分布最大吸引场的随机容量样本的次序统计量的精致渐近性,揭示了收敛速度、权函数、边界函数及极限状态之间的联系.这类吸引场真包含了全体(γ),γ>0分布族.     

双模腔场与一个V型三能级原子共振相互作用的量子统计性质

采用全量子理论和数值计算方法,研究了初始处于相干态的双模腔场与一个V型三能级原子共振相互作用的量子统计性质,讨论了在没有对原子进行态选择性测量、直接对原子进行态选择性测量和应用经典微波场并对原子进行态选择性测量的三种情况下,腔模平均光子数、耦合系数及相互作用时间对亚泊松统计、模间相干性、光子聚束反聚束效应和违背Cauchy-Schwarz不等式的影响。结果表明:对原子进行态选择性测量后,亚泊松统计特性明显地增强、模间反相关性明显地减弱、Cauchy-Schwarz不等式总是被违背;两个腔模平均光子数差比较大时,对原子进行态选择性测量后,a模腔场总是呈现反聚束效应。     

闪电光电信号的同步观测与闪电类型模式识别

利用宽带电场仪和光学纹波探头,对2006年夏季广东省从化地区发生的自然闪电的光电信号进行了同步观测,并对结果进行了统计分析。统计结果表明：闪电光信号脉冲的发生时间和峰值到达时间总是滞后于电信号,并且脉冲上升沿和宽度也比电信号宽;云闪的光信号在上述特征参数的滞后量、上升沿时间和脉宽时间差要比地闪回击放电大。从闪电光电信号时域信号特征的角度,利用BP人工神经网络,对闪电类型进行了模式识别研究。总体识别结果基本上能够满足要求,但是由于云闪放电过程比较复杂,获得的数据较少,所以对云闪识别的效果并不理想。     

Spatial,Hysteretic, and Adaptive Host–Guest Chemistry in a Metal–Organic Framework with Open Watson–Crick Sites

Biological and artificial molecules and assemblies capable of supramolecular recognition, especially those with nucleobase pairing, usually rely on autonomous or collective binding to function. Advanced site‐specific recognition takes advantage of cooperative spatial effects, as in local folding in protein–DNA binding. Herein, we report a new nucleobase‐tagged metal–organic framework (MOF), namely ZnBTCA (BTC=benzene‐1,3,5‐tricarboxyl, A=adenine), in which the exposed Watson–Crick faces of adenine residues are immobilized periodically on the interior crystalline surface. Systematic control experiments demonstrated the cooperation of the open Watson–Crick sites and spatial effects within the nanopores, and thermodynamic and kinetic studies revealed a hysteretic host–guest interaction attributed to mild chemisorption. We further exploited this behavior for adenine–thymine binding within the constrained pores, and a globally adaptive response of the MOF host was observed.     

V型三能级原子与双模奇偶纠缠相干光场相互作用系统的光子统计性质

本文采用求解Schr dinger方程和数值计算方法,研究了V-型三能级原子与双模奇偶纠缠相干光场相互作用系统的光子统计性质,结果表明:此性质与双模奇偶纠缠相干光场的纠缠程度、失谐量、原子的初态以及双模光的平均光子数相关联.     

On the eigenvalues and eigenvectors of an overlapping Markov chain

Starting with a sequence of i.i.d. [uniform] random variables with m possible values, we consider the overlapping Markov chain formed by sliding a window of size k through the i.i.d. sequence. We study the limiting covariance matrix B_k of this Markov chain and give algorithms for constructing the eigenvectors of B_k. We also discuss the applicability of the results in strengthening Pearsons ² test as well as the relation to approximate entropy and the usefulness in the area of testing the hypothesis of uniformity of random number generators.Mathematics Subject Classification (2000):Primary: 60J10; Secondary: 11K45     

ON CONFIDENCE REGIONS OF SEMIPARAMETRIC NONLINEAR REGRESSION MODELS(A GEOMETRIC APPROACH)

1IntroductionSelltipaxanetricmodelsaxemodelscolltaillingbothparametricalldnonparametriccom-pOnents,wl1erethenol1parametriccomponentplaystheroleofanusianceparameter.Moreprecisely,asellliparametriclllodelisparameterizedbyaparameterofillteresttakingvaI1lesinfinite-din1el1sionajEuclidenspaceal1danusianceparantetertakingvaluesininfinite-dimellsionalspace.Tl1ismodelembodiesacolllpro11tisebetweenemployingagelleralnonparametricspeci-ficatioll.wl1ich,iftheconditiol1il1gvariablesarehighdimensional,woul…     

On Ornstein–Uhlenbeck driven by Ornstein–Uhlenbeck processes

We investigate the asymptotic behavior of the maximum likelihood estimators of the unknown parameters of positive recurrent Ornstein–Uhlenbeck processes driven by Ornstein–Uhlenbeck processes.     

A new method for the investigation of orientation relationships in meteoritic plessite

The orientation relationship (OR) between the bcc and fcc phase in the plessite microstructure of the iron meteorites Watson, Agpalilik and Gibeon has been analysed in a scanning electron microscope using electron back‐scattered diffraction (EBSD). A very strong OR exists, independently on the analysed plessite type and the observed spreading of single orientation data. The agreement between the experimental orientation distribution and existing models varies for each meteorite. The black plessite in the Agpalilik corresponds to the Nishiyama‐Wassermann model whereas the duplex plessite of the Gibeon meteorite shows an OR close to the Kurdjumov‐Sachs model. The Watson meteorite is strongly deformed so that a general OR is difficult to determine due to the blurred experimental orientation distribution. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)