Discrete Euler processes and their applications

This paper introduces discrete Euler processes and shows their application in detecting and forecasting cycles in non‐stationary data where periodic behavior changes approximately linearly in time. A discrete Euler process becomes a classical stationary process if ‘time’ is transformed properly. By moving from one time domain to another, one may deform certain time‐varying data to non‐time‐varying data. With these non‐time‐varying data on the deformed timescale, one may use traditional tools to do parameter estimation and forecasts. The obtained results then can be transformed back to the original timescale. For datasets with an underlying discrete Euler process, the sample M‐spectrum and the spectra estimator of a Euler model (i.e., EAR spectral) are used to detect cycles of a Euler process. Beam response and whale data are used to demonstrate the usefulness of a Euler model. Copyright © 2008 John Wiley & Sons, Ltd.     

差比序列视角下“不是A但是／只是／而是B”之比较

语言中的某些词或词组可以形成一个差比序列。将不同差比序列项分别嵌入“不是A但是／只是／而是B”框架，对其嵌入条件、语义内涵和否定类别分别加以比较，可从新的视角发现这三个框架深层次的区别与联系。     

基于时间序列的灰色预测技术在估产模型中的应用

在建立估产模型过程中，引进基于时间序列的灰色预测技术，通过对样本点建立基于时间序列的灰色预测模型和常规的多元线性回归气象模型的分析比较，试图找到一种计算简单，数据要求少而精度较高，时效性较好的建模方法，为时间序列预测在农作物估产方面的应用作出一点探索。     

二元序列的广义导数

给出了序列周期的另一类定义,研究了周期二元序列的广义导数序列的周期性,得到了周期二元序列的广义导数序列的一些性质,并进一步探讨了周期分别为2N和2N-1的二元序列的广义导数。     

不定方程x3-8=65y2的解

利用同余式和递归数列的方法,证明了不定方程x3 -8=65y2无适合(x,y)=1的整数解.     

赋Orlicz范数Musielak-Orlicz序列空间中的紧局部一致凸点(英文)

给出了赋Orlicz范数Musielak-Orlicz序列空间中的紧局部一致凸点的判别准则,从而得到了赋Orlicz范数的Musielak-Orlicz序列空间是紧局部一致凸的充分必要条件。     

Ancient DNA sequences of rice from the low Yangtze reveal significant genotypic divergence

Rice (Oryza sativa) was first domesticated in the lower and middle Yangtze regions of China, and rice remains have been found in many Chinese archaeological sites. Until now, only phenotypic archeobotanical evidence, such as the spikelet bases of ancient grains, has been used to speculate on the domestication process and domestication rate of rice. In this study, we sequenced 4 genomic segments from rice remains in Tianluoshan, a site of the local Hemudu Neolithic culture in the low Yangtze and two other archaeological sites (~2400 and 1200 BC, respectively). We compared our sequences with those of the current domesticated and wild rice (O. rufipogon) populations. At least two genotypes were found in the remains from each site, suggesting a heterozygotic state of the rice seeds. One ancient genotype was not found in the current domesticated population and might have been lost. The rice remains belonged to the japonica group, and most if not all were japonica-type, suggesting that the remains might be at an early stage of indica-japonica divergence or an indica-japonica mixture. We also identified sequences with significant similarity to those from species of Sapindales, Zygophyllales, and Brassicales, which is consistent with the identification of other plant remains in the Tianluoshan site and the common rice field weeds such as mustards in southern China.     

双参数Co半群的收敛性问题

本文给出了有关双参数C0半群的一些性质,研究了双参数C0半群收敛性问题,借助单参数C0半群与双参数C0半群之间的关系,在一定条件下,将单参数C0半群序列的收敛性推广到了双参数C0半群上.     

A Study of Value‐at‐Risk Based on M‐Estimators of the Conditional Heteroscedastic Models

In this paper, we investigate the performance of a class of M‐estimators for both symmetric and asymmetric conditional heteroscedastic models in the prediction of value‐at‐risk. The class of estimators includes the least absolute deviation (LAD), Huber's, Cauchy and B‐estimator, as well as the well‐known quasi maximum likelihood estimator (QMLE). We use a wide range of summary statistics to compare both the in‐sample and out‐of‐sample VaR estimates of three well‐known stock indices. Our empirical study suggests that in general Cauchy, Huber and B‐estimator have better performance in predicting one‐step‐ahead VaR than the commonly used QMLE. Copyright © 2011 John Wiley & Sons, Ltd.     

两类差集偶的直接构造

给出两类差集偶的直接构造,证明了(4t,2t-2,2t,t-1,t-1)-差集偶和(4t,2t,2t,t,t)-差集偶的存在性。