Recently people proved that every f∈C[0, 1] can be uniformly approximated by polynomial sequences {P_n}, {Q_n} such for any x∈[0,1] and n=1,2,…that Q_n(x)<Q_(n+1)(x)<f(x)<P_(n+1)(x)<P_n(x). For example...Recently people proved that every f∈C[0, 1] can be uniformly approximated by polynomial sequences {P_n}, {Q_n} such for any x∈[0,1] and n=1,2,…that Q_n(x)<Q_(n+1)(x)<f(x)<P_(n+1)(x)<P_n(x). For example, Xie and Zhou showed that one can construct such monotone polynomial sequences which do achieve the best uniform approximation rate for a continuous func- tion. Actually they obtained a result as ‖P_n(x)-Q_n(x)‖≤42E_n (f), (1) which essentially improved a conclusion in Gal and Szabados. The present paper, by optimal procedure, improves this inequality to ‖[P_n(x)-Q_n(x)‖≤(18+ε)E_n(f), where εis any positive real number.展开更多
Taking Deyang as an example of middle and small city, this paper analysesmain factors related to industry development, constructs an appropriateAnalytic Hierarchy Process (AHP) model, and finally obtains the priordeve...Taking Deyang as an example of middle and small city, this paper analysesmain factors related to industry development, constructs an appropriateAnalytic Hierarchy Process (AHP) model, and finally obtains the priordevelopment sequence of major industries of Deyang.展开更多
Based on more exquisitely preserved specimens of Markuelia hunanensis recently recovered from Middle and Upper Cambrian in western Hunan and in the light of Synchrotron radiation X-ray tomo-graphic microscopy,the deve...Based on more exquisitely preserved specimens of Markuelia hunanensis recently recovered from Middle and Upper Cambrian in western Hunan and in the light of Synchrotron radiation X-ray tomo-graphic microscopy,the developmental sequence from cleavage through organogenesis to the pre-hatching of Cambrian embryo Markuelia,especially the developmental sequence during the pre-hatching stage,i.e.from the earliest period when the scalids and tail spines only took shape to the latest period(just about hatching),is established.This developmental sequence provides a pattern of embryonic development during the pre-hatching stage,which has not been established in the living scalidophorans(priapulids,loriciferans and kinorhynchs).Thus,it not only enriches our knowledge on the embryonic development of the extant descendants of Markuelia,but also opens a new window to the evolution and development of the animal.展开更多
MicroRNAs(miRNAs) are small non-coding RNAs that regulate a variety of biological processes. miRNA expression often exhibits spatial and temporal specificity. However, genome-wide miRNA expression patterns in differen...MicroRNAs(miRNAs) are small non-coding RNAs that regulate a variety of biological processes. miRNA expression often exhibits spatial and temporal specificity. However, genome-wide miRNA expression patterns in different organs during development of Arabidopsis thaliana have not yet been systemically investigated. In this study, we sequenced small RNA libraries generated from 27 different organ/tissue types, which cover the entire life cycle of Arabidopsis. Analysis of the sequencing data revealed that most miRNAs are ubiquitously expressed, whereas a small set of miRNAs display highly specific expression patterns. In addition, different miRNA members within the same family have distinct spatial and temporal expression patterns. Moreover, we found that some miRNAs are produced from different arms of their hairpin precursors at different developmental stages. This work provides new insights into the regulation of miRNA biogenesis and a rich resource for future investigation of miRNA functions in Arabidopsis.展开更多
文摘Recently people proved that every f∈C[0, 1] can be uniformly approximated by polynomial sequences {P_n}, {Q_n} such for any x∈[0,1] and n=1,2,…that Q_n(x)<Q_(n+1)(x)<f(x)<P_(n+1)(x)<P_n(x). For example, Xie and Zhou showed that one can construct such monotone polynomial sequences which do achieve the best uniform approximation rate for a continuous func- tion. Actually they obtained a result as ‖P_n(x)-Q_n(x)‖≤42E_n (f), (1) which essentially improved a conclusion in Gal and Szabados. The present paper, by optimal procedure, improves this inequality to ‖[P_n(x)-Q_n(x)‖≤(18+ε)E_n(f), where εis any positive real number.
文摘Taking Deyang as an example of middle and small city, this paper analysesmain factors related to industry development, constructs an appropriateAnalytic Hierarchy Process (AHP) model, and finally obtains the priordevelopment sequence of major industries of Deyang.
基金Supported by the National Natural Science Foundation of China(Grant Nos.40572003 and 40372001)the Research Fund for Doctoral Program of High Educa-tion(Grant Nos.20060001059 and 2000000127)Laboratory of Paleobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology,Chinese Academy of Sciences(Grant No.023106)
文摘Based on more exquisitely preserved specimens of Markuelia hunanensis recently recovered from Middle and Upper Cambrian in western Hunan and in the light of Synchrotron radiation X-ray tomo-graphic microscopy,the developmental sequence from cleavage through organogenesis to the pre-hatching of Cambrian embryo Markuelia,especially the developmental sequence during the pre-hatching stage,i.e.from the earliest period when the scalids and tail spines only took shape to the latest period(just about hatching),is established.This developmental sequence provides a pattern of embryonic development during the pre-hatching stage,which has not been established in the living scalidophorans(priapulids,loriciferans and kinorhynchs).Thus,it not only enriches our knowledge on the embryonic development of the extant descendants of Markuelia,but also opens a new window to the evolution and development of the animal.
基金supported by grants fromNational Key Research and Development Program of China (2016YFA0500800)National Natural Science Foundation of China (31421001, 31225015) to Yijun Qi
文摘MicroRNAs(miRNAs) are small non-coding RNAs that regulate a variety of biological processes. miRNA expression often exhibits spatial and temporal specificity. However, genome-wide miRNA expression patterns in different organs during development of Arabidopsis thaliana have not yet been systemically investigated. In this study, we sequenced small RNA libraries generated from 27 different organ/tissue types, which cover the entire life cycle of Arabidopsis. Analysis of the sequencing data revealed that most miRNAs are ubiquitously expressed, whereas a small set of miRNAs display highly specific expression patterns. In addition, different miRNA members within the same family have distinct spatial and temporal expression patterns. Moreover, we found that some miRNAs are produced from different arms of their hairpin precursors at different developmental stages. This work provides new insights into the regulation of miRNA biogenesis and a rich resource for future investigation of miRNA functions in Arabidopsis.
