Although the first microscopic observations on soils date already from the beginning of the twentieth century, the publication of Kubiena＇s book ＂Micropedology＂ in 1937 is considered as the beginning of this new sc...Although the first microscopic observations on soils date already from the beginning of the twentieth century, the publication of Kubiena＇s book ＂Micropedology＂ in 1937 is considered as the beginning of this new scientific discipline. This first system for micromorphological descriptions of soils is considered as morphoanalytical, analysing the fabric according to pure morphological criteria. In a second period Kuniena used a morphogenetic approach, directly relating the global observed fabric to genetic soil horizons. This system, mainly limited to European soils, was in general use till the early nineteen-seventies. End of the nineteen-fifties non- genetic soil classification systems were developed （e.g. USDA）. This trend prompted R. Brewer to publish in 1964 a new morphoanalytical system for fabric analysis, used till the end of last century. Because of some inconsistencies in this approach, a working group of the ISSS published in 1985 a new set of morphoanalytical concepts and associated terminology （Bullock et al.）, in 2003 adapted and extended by Stoops. Several morphosynthetic systems, expressing a complete soil microfabric in a single （compound） term have been proposed, but none was really successful. In 1967 Kubiena introduced the term ＂micromorphometry＂ to name a new branch of micromorphology quantifying the soil fabric, mainly evaluating changes in porosity and structure resulting from soil management. The necessity of dearly defined concepts and terms for fabric analysis of soils and regoliths, even as a need for standardisation of quantitative methods, are discussed in the conclusions.展开更多
Recurrent events data with a terminal event （e.g., death） often arise in clinical and ob- servational studies. Variable selection is an important issue in all regression analysis. In this paper, the authors first pr...Recurrent events data with a terminal event （e.g., death） often arise in clinical and ob- servational studies. Variable selection is an important issue in all regression analysis. In this paper, the authors first propose the estimation methods to select the significant variables, and then prove the asymptotic behavior of the proposed estimator. Furthermore, the authors discuss the computing algorithm to assess the proposed estimator via the linear function approximation and generalized cross validation method for determination of the tuning parameters. Finally, the finite sample estimation for the asymptotical covariance matrix is also proposed.展开更多
文摘Although the first microscopic observations on soils date already from the beginning of the twentieth century, the publication of Kubiena＇s book ＂Micropedology＂ in 1937 is considered as the beginning of this new scientific discipline. This first system for micromorphological descriptions of soils is considered as morphoanalytical, analysing the fabric according to pure morphological criteria. In a second period Kuniena used a morphogenetic approach, directly relating the global observed fabric to genetic soil horizons. This system, mainly limited to European soils, was in general use till the early nineteen-seventies. End of the nineteen-fifties non- genetic soil classification systems were developed （e.g. USDA）. This trend prompted R. Brewer to publish in 1964 a new morphoanalytical system for fabric analysis, used till the end of last century. Because of some inconsistencies in this approach, a working group of the ISSS published in 1985 a new set of morphoanalytical concepts and associated terminology （Bullock et al.）, in 2003 adapted and extended by Stoops. Several morphosynthetic systems, expressing a complete soil microfabric in a single （compound） term have been proposed, but none was really successful. In 1967 Kubiena introduced the term ＂micromorphometry＂ to name a new branch of micromorphology quantifying the soil fabric, mainly evaluating changes in porosity and structure resulting from soil management. The necessity of dearly defined concepts and terms for fabric analysis of soils and regoliths, even as a need for standardisation of quantitative methods, are discussed in the conclusions.
文摘Recurrent events data with a terminal event （e.g., death） often arise in clinical and ob- servational studies. Variable selection is an important issue in all regression analysis. In this paper, the authors first propose the estimation methods to select the significant variables, and then prove the asymptotic behavior of the proposed estimator. Furthermore, the authors discuss the computing algorithm to assess the proposed estimator via the linear function approximation and generalized cross validation method for determination of the tuning parameters. Finally, the finite sample estimation for the asymptotical covariance matrix is also proposed.
