基于互信息的功能磁共振图像配准

互信息作为衡量两幅图像配准的相似性测度函数,当两幅图像配准时,互信息达到最大值。该文提出了基于互信息脑功能磁共振图像配准新方法,采用了无需计算梯度的Powell直接搜索算法,并通过多分辨的方式加快了图像配准速度。磁共振的配准实验证明,互信息法能准确地实现多模态医学图像的配准,并且能达到亚像素的精度。     

Real nonparametric regression using complex wavelets

Summary.  Wavelet shrinkage is an effective nonparametric regression technique, especially when the underlying curve has irregular features such as spikes or discontinuities. The basic idea is simple: take the discrete wavelet transform of data consisting of a signal corrupted by noise; shrink or remove the wavelet coefficients to remove the noise; then invert the discrete wavelet transform to form an estimate of the true underlying curve. Various researchers have proposed increasingly sophisticated methods of doing this by using real-valued wavelets. Complex-valued wavelets exist but are rarely used. We propose two new complex-valued wavelet shrinkage techniques: one based on multiwavelet style shrinkage and the other using Bayesian methods. Extensive simulations show that our methods almost always give significantly more accurate estimates than methods based on real-valued wavelets. Further, our multiwavelet style shrinkage method is both simpler and dramatically faster than its competitors. To understand the excellent performance of this method we present a new risk bound on its hard thresholded coefficients.     

A general inverse sampling scheme and its application to adaptive cluster sampling

Not having a variance estimator is a seriously weak point of a sampling design from a practical perspective. This paper provides unbiased variance estimators for several sampling designs based on inverse sampling, both with and without an adaptive component. It proposes a new design, which is called the general inverse sampling design, that avoids sampling an infeasibly large number of units. The paper provide estimators for this design as well as its adaptive modification. A simple artificial example is used to demonstrate the computations. The adaptive and non‐adaptive designs are compared using simulations based on real data sets. The results indicate that, for appropriate populations, the adaptive version can have a substantial variance reduction compared with the non‐adaptive version. Also, adaptive general inverse sampling with a limitation on the initial sample size has a greater variance reduction than without the limitation.     

论消费者的知觉风险及营销对策

消费者产生知觉风险的原因众多。我们可根据消费者收集信息的不同程度和消费者收集信息的性质而采取不同的营销策略来减低消费者的知觉风险,加快消费者的购买决策。     

The analysis of incomplete data using stochastic covariates

In the development of many diseases there are often associated random variables which continuously reflect the progress of a subject towards the final expression of the disease (failure). At any given time these processes, which we call stochastic covariates, may provide information about the current hazard and the remaining time to failure. Likewise, in situations when the specific times of key prior events are not known, such as the time of onset of an occult tumour or the time of infection with HIV-1, it may be possible to identify a stochastic covariate which reveals, indirectly, when the event of interest occurred. The analysis of carcinogenicity trials which involve occult tumours is usually based on the time of death or sacrifice and an indicator of tumour presence for each animal in the experiment. However, the size of an occult tumour observed at the endpoint represents data concerning tumour development which may convey additional information concerning both the tumour incidence rate and the rate of death to which tumour-bearing animals are subject. We develop a stochastic model for tumour growth and suggest different ways in which the effect of this growth on the hazard of failure might be modelled. Using a combined model for tumour growth and additive competing risks of death, we show that if this tumour size information is used, assumptions concerning tumour lethality, the context of observation or multiple sacrifice times are no longer necessary in order to estimate the tumour incidence rate. Parametric estimation based on the method of maximum likelihood is outlined and is applied to simulated data from the combined model. The results of this limited study confirm that use of the stochastic covariate tumour size results in more precise estimation of the incidence rate for occult tumours.     

Modified cross-validation in density estimation

We propose a new modified (biased) cross-validation method for adaptively determining the bandwidth in a nonparametric density estimation setup. It is shown that the method provides consistent minimizers. Some simulation results are reported on which compare the small sample behavior of the new and the classical cross-validation selectors.     

商品化权刍议

结合国内外相关案例、理论和我国在经济生活中引发的诉讼 ,对商品化权引入的必要性及其主体、客体和内容等诸问题进行了探讨 ,认为在现实生活中有必要引入商品化权 ,以此明确权利 ,更好的保护权利人的利益 ,推动我国经济有序、健康发展     

位相物体像全息图的拍摄

讨论了位相物体激光像面全息摄影的特点，从全息与橱窗装饰艺术结合的设想出发，设计了位相物体像全息图的拍摄实验，取得好的实验教学效果．     

试论文本的意象空间和生命世界——兼论李煜的词

文学语言凭借意象建构意义世界。意象是艺术创造主体生命意识与客体融合同构的结晶 ,是艺术形象诞生的前提。李煜词中的意象蕴涵着生命意味 ,它通过文本的意象来展现艺术创作过程中主体与客体的关系。     

简论诗的意象运动

诗的意象运动的动力源在于情感 ,是情的流动引起包括情与理两端的意的流动 ,又是情和意的流动造成象的跃动。因为情和意如气体或液体呈线型流动 ,像如固体作块状跃动 ,所以在诗的意象运动中 ,往往出现象断而意连的状况。