Towards Uniformly Efficient Trend Estimation Under Weak/Strong Correlation and Non‐stationary Volatility

In this paper, we consider the deterministic trend model where the error process is allowed to be weakly or strongly correlated and subject to non‐stationary volatility. Extant estimators of the trend coefficient are analysed. We find that under heteroskedasticity, the Cochrane–Orcutt‐type estimator (with some initial condition) could be less efficient than Ordinary Least Squares (OLS) when the process is highly persistent, whereas it is asymptotically equivalent to OLS when the process is less persistent. An efficient non‐parametrically weighted Cochrane–Orcutt‐type estimator is then proposed. The efficiency is uniform over weak or strong serial correlation and non‐stationary volatility of unknown form. The feasible estimator relies on non‐parametric estimation of the volatility function, and the asymptotic theory is provided. We use the data‐dependent smoothing bandwidth that can automatically adjust for the strength of non‐stationarity in volatilities. The implementation does not require pretesting persistence of the process or specification of non‐stationary volatility. Finite‐sample evaluation via simulations and an empirical application demonstrates the good performance of proposed estimators.     

Stigma, HIV/AIDS and prevention of mother-to-child transmission in Zambia

This report evaluates the extent of perceived and enacted HIV/AIDS-related stigma in a rural setting in Zambia. Stigmatisation is abundant, ranging from subtle actions to the most extreme degradation, rejection and abandonment. Women with HIV and pregnant women assumed to be HIV positive are repeatedly subjected to extensive forms of stigma, particularly once they become sick or if their child dies. Despite increasing access to prevention of mother to child transmission initiatives, including anti-retroviral drugs, the perceived disincentives of HIV testing, particularly for women, largely outweigh the potential gains from available treatments. HIV/AIDS related stigma drives the epidemic underground and is one of the main reasons that people do not wish to know their HIV status. Unless efforts to reduce stigma are, as one peer educator put it, “written in large letters in any HIV/AIDS campaign rather than small”, stigma will remain a major barrier to curbing the HIV/AIDS pandemic.     

时装画与服装文化

时装画是为了服装的设计、制作和推介而创作的具有审美价值的绘画样式。时装画对于服装文化的发展具有推动作用 ,探讨和研究时装画产生、发展的历史和现状 ,对于发展中国的服装文化 ,具有重要的意义。     

LOG-PERIODOGRAM ESTIMATION OF LONG MEMORY VOLATILITY DEPENDENCIES WITH CONDITIONALLY HEAVY TAILED RETURNS

Many recent papers have used semiparametric methods, especially the log-periodogram regression, to detect and estimate long memory in the volatility of asset returns. In these papers, the volatility is proxied by measures such as squared, log-squared, and absolute returns. While the evidence for the existence of long memory is strong using any of these measures, the actual long memory parameter estimates can be sensitive to which measure is used. In Monte-Carlo simulations, I find that if the data is conditionally leptokurtic, the log-periodogram regression estimator using squared returns has a large downward bias, which is avoided by using other volatility measures. In United States stock return data, I find that squared returns give much lower estimates of the long memory parameter than the alternative volatility measures, which is consistent with the simulation results. I conclude that researchers should avoid using the squared returns in the semiparametric estimation of long memory volatility dependencies.     

"黔电送粤"中水电真实移民成本问题研究

现行“黔电送粤”的电价未能反映真实移民成本。理应在厘清真实移民成本主要组成部分的基础上,在谈判和核定电价时加以考虑,促使真实移民成本成为电价的构成要素,这对于解决各族移民的脱贫致富,具有重要意义。     

Refined Inference on Long Memory in Realized Volatility

There is an emerging consensus in empirical finance that realized volatility series typically display long range dependence with a memory parameter (d) around 0.4 (Andersen et al., 2001; Martens et al., 2004). The present article provides some illustrative analysis of how long memory may arise from the accumulative process underlying realized volatility. The article also uses results in Lieberman and Phillips (2004, 2005) to refine statistical inference about d by higher order theory. Standard asymptotic theory has an O(n^-1/2) error rate for error rejection probabilities, and the theory used here refines the approximation to an error rate of o(n^-1/2). The new formula is independent of unknown parameters, is simple to calculate and user-friendly. The method is applied to test whether the reported long memory parameter estimates of Andersen et al. (2001) and Martens et al. (2004) differ significantly from the lower boundary (d = 0.5) of nonstationary long memory, and generally confirms earlier findings.     

试论英语教学中教师的主导作用

本文从道德教育、文化传播、知识传授和能力培养等四个方面论述了在英语教学中教师的主导作用,阐述了英语教学中教师主导作用的重要性。     

抗战时期中国工业的西迁与西部的开发

出于抗战和生存的需要 ,国民政府进行了大规模的工业内迁 ,从而对西南地区的工业化进程起到了重大的推动作用 ,成为中国近现代史上一次规模最大、内容最典型的工业化空间传动运动。这种非经济性动力引发的工业化空间传动也存在一定的弊端。     

论信息时代的数字图像传播

信息时代的数字图像带来了社会文化新的发展空间,数字图像以其逼真、形象、快速、虚拟的特点成为我们这个读图时代的宠儿。数字图像是视觉文化的一个构成元素,当然,视觉文化不只是艺术,凡是人们可以通过视知觉感受而直接获取信息与解读意义的文化样式都可以纳入视觉文化的范畴。这种新的文化形式,促进了人们思维能力的提高并对人们的生活方式产生了深刻影响。     

HEAVY-TAILED-DISTRIBUTED THRESHOLD STOCHASTIC VOLATILITY MODELS IN FINANCIAL TIME SERIES

To capture mean and variance asymmetries and time‐varying volatility in financial time series, we generalize the threshold stochastic volatility (THSV) model and incorporate a heavy‐tailed error distribution. Unlike existing stochastic volatility models, this model simultaneously accounts for uncertainty in the unobserved threshold value and in the time‐delay parameter. Self‐exciting and exogenous threshold variables are considered to investigate the impact of a number of market news variables on volatility changes. Adopting a Bayesian approach, we use Markov chain Monte Carlo methods to estimate all unknown parameters and latent variables. A simulation experiment demonstrates good estimation performance for reasonable sample sizes. In a study of two international financial market indices, we consider two variants of the generalized THSV model, with US market news as the threshold variable. Finally, we compare models using Bayesian forecasting in a value‐at‐risk (VaR) study. The results show that our proposed model can generate more accurate VaR forecasts than can standard models.