24,379 research outputs found

    Distinguish Coding And Noncoding Sequences In A Complete Genome Using Fourier Transform

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    A Fourier transform method is proposed to distinguish coding and non-coding sequences in a complete genome based on a number sequence representation of the DNA sequence proposed in our previous paper (Zhou et al., J. Theor. Biol. 2005) and the imperfect periodicity of 3 in protein coding sequences. The three parameters P_x(S) (1), P_x(S) (1/3) and P_x(S) (1/36) in the Fourier transform of the number sequence representation of DNA sequences are selected to form a three-dimensional parameter space. Each DNA sequence is then represented by a point in this space. The points corresponding to coding and non-coding sequences in the complete genome of prokaryotes are seen to be divided into different regions. If the point (P_x(�ar S) (1), Px(�ar S) (1/3), P_x(�ar S) (1/36)) for a DNA sequence is situated in the region corresponding to coding sequences, the sequence is distinguished as a coding sequence; otherwise, the sequence is classified as a noncoding one. Fisher's discriminant algorithm is used to study the discriminant accuracy. The average discriminant accuracies pc, pnc, qc and qnc of all 51 prokaryotes obtained by the present method reach 81.02%, 92.27%, 80.77% and 92.24% respectively

    Changes in Snow Phenology from 1979 to 2016 over the Tianshan Mountains, Central Asia

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    Snowmelt from the Tianshan Mountains (TS) is a major contributor to the water resources of the Central Asian region. Thus, changes in snow phenology over the TS have significant implications for regional water supplies and ecosystem services. However, the characteristics of changes in snow phenology and their influences on the climate are poorly understood throughout the entire TS due to the lack of in situ observations, limitations of optical remote sensing due to clouds, and decentralized political landscapes. Using passive microwave remote sensing snow data from 1979 to 2016 across the TS, this study investigates the spatiotemporal variations of snow phenology and their attributes and implications. The results show that the mean snow onset day (Do), snow end day (De), snow cover duration days (Dd), and maximum snow depth (SDmax) from 1979 to 2016 were the 78.2nd day of hydrological year (DOY), 222.4th DOY, 146.2 days, and 16.1 cm over the TS, respectively. Dd exhibited a spatial distribution of days with a temperature of \u3c0 \u3e°C derived from meteorological station observations. Anomalies of snow phenology displayed the regional diversities over the TS, with shortened Dd in high-altitude regions and the Fergana Valley but increased Dd in the Ili Valley and upper reaches of the Chu and Aksu Rivers. Increased SDmax was exhibited in the central part of the TS, and decreased SDmax was observed in the western and eastern parts of the TS. Changes in Dd were dominated by earlier De, which was caused by increased melt-season temperatures (Tm). Earlier De with increased accumulation of seasonal precipitation (Pa) influenced the hydrological processes in the snowmelt recharge basin, increasing runoff and earlier peak runoff in the spring, which intensified the regional water crisi

    A Mutual Information Based Sequence Distance For Vertebrate Phylogeny Using Complete Mitochondrial Genomes

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    Traditional sequence distances require alignment. A new mutual information based sequence distance without alignment is defined in this paper. This distance is based on compositional vectors of DNA sequences or protein sequences from complete genomes. First we establish the mathematical foundation of this distance. Then this distance is applied to analyze the phylogenetic relationship of 64 vertebrates using complete mitochondrial genomes. The phylogenetic tree shows that the mitochondrial genomes are separated into three major groups. One group corresponds to mammals; one group corresponds to fish; and the last one is Archosauria (including birds and reptiles). The structure of the tree based on our new distance is roughly in agreement in topology with the current known phylogenies of vertebrates

    Study on radiative decays of DsJ(2860)D^*_{sJ}(2860) and Ds1(2710)D^*_{s1}(2710) into DsD_s by means of LFQM

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    The observed resonance peak around 2.86 GeV has been carefully reexamined by the LHCb collaboration and it is found that under the peak there reside two states Ds1(2860)D^*_{s1}(2860) and Ds3(2860)D^*_{s3}(2860) which are considered as 13D1(csˉ)1^3D_1(c\bar s) and 13D3(csˉ)1^3D_3(c\bar s) with slightly different masses and total widths. Thus, the earlier assumption that the resonance Ds1(2710)D^*_{s1}(2710) was a 1D1D state should not be right. We suggest to measure the partial widths of radiative decays of DsJ(2860)D^*_{sJ}(2860) and Ds1(2710)D^*_{s1}(2710) to confirm their quantum numbers. We would consider Ds1(2710)D^*_{s1}(2710) as 23S12^3S_1 or a pure 13D11^3D_1 state, or their mixture and respectively calculate the corresponding branching ratios as well as those of DsJ(2860)D^*_{sJ}(2860). The future precise measurement would provide us information to help identifying the structures of those resonances .Comment: 8 pages, 4 figures, 1 tabl