Functional principal component analysis for the explorative analysis of multisite–multivariate air pollution time series with long gaps

The knowledge of the urban air quality represents the first step to face air pollution issues. For the last decades many cities can rely on a network of monitoring stations recording concentration values for the main pollutants. This paper focuses on functional principal component analysis (FPCA) to investigate multiple pollutant datasets measured over time at multiple sites within a given urban area. Our purpose is to extend what has been proposed in the literature to data that are multisite and multivariate at the same time. The approach results to be effective to highlight some relevant statistical features of the time series, giving the opportunity to identify significant pollutants and to know the evolution of their variability along time. The paper also deals with missing value issue. As it is known, very long gap sequences can often occur in air quality datasets, due to long time failures not easily solvable or to data coming from a mobile monitoring station. In the considered dataset, large and continuous gaps are imputed by empirical orthogonal function procedure, after denoising raw data by functional data analysis and before performing FPCA, in order to further improve the reconstruction.     

Designing from activities. The "ability /difficulty table", a useful tool to detect the "limit users" in the Design for All Approach

In the Design for All Approach (DfA), an important phase of the design process consists in the individuation of the so-called "limit users", that are that particular group of people with the most "critical" features for the autonomous fruition of a system or a product. Generally, however, it is not easy to identify them in a complete and objective way. A clear and complete outline of design requirements with respect to the "normal" use of a service, product or environment, moreover, is of fundamental importance in inclusive design. In fact, we know how bad design, that doesn't take in account the true "strategies of use", may lead to situations of handicap, also serious, temporary or permanent, regardless if the user is a "disabled" person or not. In relation to this scenario, the paper shows the results of a research which has developed the "Ability/Difficulty Table" ("A/D Table"), a new tool useful to identify the so-called "limit users" and their needs with respect to different activities, linking the main "difficulties", expressed by people, with the "abilities" required to carry out in autonomy the investigated activity.     

中国传统的非逻辑思维方式对博士生创造性思维生成的启示

非逻辑思维是中国传统思维的组成部分,它内含着重要的创造性品质,这种创造性品质对于当代博士生提高创造性思维能力具有重要意义。     

战后日本学术界近代中国东北史研究述评

日本学界在战前就十分关注对中国东北地区的研究，战后则经过五十至七十年代的复苏休整，八、九十年代以来形成近代东北史研究的繁荣局面，在各种新的理论方法的影响下，取得了令人瞩目的成就，其经验与教训值得我国学者学习与借鉴。     

试论“摸起来”与“摸上去”

感官动词"摸"所构成的动补结构"摸起来"、"摸上去",二者在语义、句法、语用、单位性质等方面存在着异同。两者在语法单位性质上根据二者语义的不同可视为短语或正向词过渡的短语。     

The Protective Impact of a Covariate on Competing Failures with an Example from a Bone Marrow Transplantation Study

Starting from an applied Bone Marrow Transplantation(BMT) study, the problem of “unexpected protectivity” in competing risks models is introduced, which occurs when one covariate shows a protective impact not expected from a medical perspective. Current explanations found in the statistical literature suggest that unexpected protectivity might be due to the lack of independence between the competing failures. Actually, in the presence of dependence, the Kaplan-Meier curves are not interpretable. Conversely, the cumulative incidence curves remain interpretable, and therefore seem to be a candidate for solving the problem. We discuss the particular nature of dependence in a competing risks framework and illustrate how this dependence may be created via a common frailty factor. A Monte Carlo experiment is set up which accounts also for the association between the observable covariates and the frailty factor. The aim of the experiment is to understand whether and how the bias showed by the estimates could be related to the omitted frailty variable. The results show that dependence alone does not cause false protectivity, and that the cumulative incidence curves suffer the same bias as the survival curves and therefore do not seem to be a solution to false protectivity. Conversely, false protectivity may occur according to the magnitude and the sign of the dependence between the frailty factor and the covariate. The paper ends with some suggestions for empirical research. This revised version was published online in July 2006 with corrections to the Cover Date.     

论我国土地宏观调控

土地宏观调控是政府以土地作为手段调控宏观经济运行的政策和措施的综合。我国已将土地宏观调控作为宏观经济调控的重要手段之一。分析了我国实行土地宏观调控的主要动因,论述了我国土地宏观调控的主要内容,提出了提高土地宏观调控政策效果的措施。     

特种Nafion溶液制备及其在PEMFC中的应用研究

Nafion溶液在燃料电池、电极修饰、电化学分析、电化学催化等领域具有广泛用途。采用特种高沸点溶剂,获得了溶铸性能优良Nafion的溶液。比较溶铸Nafion膜与原始Nafion膜的IR光谱可以看出,Nafion溶液制备方法未对Nafion膜的化学组成与分子结构产生影响,但溶铸膜的分子排列更加规整有序。将该溶液在PEMFC中应用,其性能优于目前的商品水-醇体系Nafion溶液。     

嘉陵江洪化元年洪水问题

在四川长江干流及其支流嘉陵江流域曾发现多处“洪化元年洪水”岩刻，有学者据此认定该年嘉陵江流域发生过特大洪水。此文以为，洪化元年应为1679年，即康熙十八年，该年嘉陵江流域没有发生过特大洪水。