MicroRNAs (miRNAs) are 20-22 nucleotide non-coding RNAs that play important roles in plant and animal development. They are usually processed from larger precursors that can form stem-loop structures. Among 20 miRNA f...MicroRNAs (miRNAs) are 20-22 nucleotide non-coding RNAs that play important roles in plant and animal development. They are usually processed from larger precursors that can form stem-loop structures. Among 20 miRNA families that are conserved between Arabidopsis and rice, the rice miR395 gene family was unique because it was organized into compact clusters that could be transcribed as one single transcript. We show here that in fact this family had four clusters of total 24 genes. Three of these clusters were segmental duplications. They contained miR395 genes of both 120 bp and 66 bp long. However, only the latter was repeatedly duplicated. The fourth cluster contained miR395 genes of two different sizes that could be the consequences of intergenic recombination of genes from the first three clusters. On each cluster, both 1-duplication and 2-duplication histories were observed based on the sequence similarity between miR395 genes, some of which were nearly identical suggesting a recent origin. This was supported by a miR395 locus survey among several species of the genus Oryza, where two clusters were only found in species with an AA genome, the genome of the cultivated rice. A comparative study of the genomic organization of Medicago truncatula miR395 gene family showed significant expansion of intergenic spaces indicating that the originally clustered genes were drifting away from each other. The diverse genomic organizations of a conserved microRNA gene family in different plant genomes indicated that this important negative gene regulation system has undergone dramatic tune-ups in plant genomes.展开更多
YBa_2Cu_(3-x)Nb_xO_(7-y) superconductors have been prepared. XRD shows that the system remains orthorhombic for all composition. Substitution of Nb^(5+) for Cu^(2+) occurs in the Cu(2) sites. The introduction of the N...YBa_2Cu_(3-x)Nb_xO_(7-y) superconductors have been prepared. XRD shows that the system remains orthorhombic for all composition. Substitution of Nb^(5+) for Cu^(2+) occurs in the Cu(2) sites. The introduction of the Nb^(5+) ions produces some extra free-electrons. These electrons recombine with the carriers of the system. It makes the mobility and the Hall number of YBa_2Cu_(3-x)Nb_xO_(7-y) decrease and also result in a depression in Tc.展开更多
Radiotherapy for Brain Metastases Brain metastases are common in patients with malignant tumors.According to the reports from autopsy,surgery and imaging investigations,the incidence of brain metastases is approximate...Radiotherapy for Brain Metastases Brain metastases are common in patients with malignant tumors.According to the reports from autopsy,surgery and imaging investigations,the incidence of brain metastases is approximately 20%~40%[1].The main symptoms are headache,dementia and motor dysfunction.The most common primary sites are lung,breast,colorectal,melanoma and kidney.展开更多
The instability property of the standing wave uω（t, x） = eiωtφ（x） for the Klein–Gordon– Hartree equation is investigated. For the case N≥3 and w2 〈2/N＋4-γ,it is shown that the standing wave eiwtφ（x） is...The instability property of the standing wave uω（t, x） = eiωtφ（x） for the Klein–Gordon– Hartree equation is investigated. For the case N≥3 and w2 〈2/N＋4-γ,it is shown that the standing wave eiwtφ（x） is strongly unstable by blow-up in finite time.展开更多
本文研究方程驻波的强不稳定性iut＋△u＋a｜u｜p-1u＋E1（｜u｜2）u=0，t≥0，z∈Rn，其中a〉0，1〈p〈n＋2/（n-2）＋,n∈{2，3}，当1＋4/n≤p〈n＋2/（n-2）＋时，文[Sharpthreshold of global existence and instability of standin...本文研究方程驻波的强不稳定性iut＋△u＋a｜u｜p-1u＋E1（｜u｜2）u=0，t≥0，z∈Rn，其中a〉0，1〈p〈n＋2/（n-2）＋,n∈{2，3}，当1＋4/n≤p〈n＋2/（n-2）＋时，文[Sharpthreshold of global existence and instability of standing wave for a Davey-Stewartsonsystem, Commun. Math. Phys., 2008, 283：93 125]在驻波的频率满足一定假设条件下，证明了此方程驻波的强不稳定性．本文去掉这个假设，得到相同的结论．展开更多
基金supported in part by a grant from Northern Illinois University Foundation to Long MAONational Institutes of Health(NIH)grant to Mitrick JOHNS and Long MAO(No.44-G1A62164)a grant from the National Natural Science Foundation of China for oversea young scholars to Long MAO(No.30228022).
文摘MicroRNAs (miRNAs) are 20-22 nucleotide non-coding RNAs that play important roles in plant and animal development. They are usually processed from larger precursors that can form stem-loop structures. Among 20 miRNA families that are conserved between Arabidopsis and rice, the rice miR395 gene family was unique because it was organized into compact clusters that could be transcribed as one single transcript. We show here that in fact this family had four clusters of total 24 genes. Three of these clusters were segmental duplications. They contained miR395 genes of both 120 bp and 66 bp long. However, only the latter was repeatedly duplicated. The fourth cluster contained miR395 genes of two different sizes that could be the consequences of intergenic recombination of genes from the first three clusters. On each cluster, both 1-duplication and 2-duplication histories were observed based on the sequence similarity between miR395 genes, some of which were nearly identical suggesting a recent origin. This was supported by a miR395 locus survey among several species of the genus Oryza, where two clusters were only found in species with an AA genome, the genome of the cultivated rice. A comparative study of the genomic organization of Medicago truncatula miR395 gene family showed significant expansion of intergenic spaces indicating that the originally clustered genes were drifting away from each other. The diverse genomic organizations of a conserved microRNA gene family in different plant genomes indicated that this important negative gene regulation system has undergone dramatic tune-ups in plant genomes.
基金This project was supported by National Matural Science foundation of China.
文摘YBa_2Cu_(3-x)Nb_xO_(7-y) superconductors have been prepared. XRD shows that the system remains orthorhombic for all composition. Substitution of Nb^(5+) for Cu^(2+) occurs in the Cu(2) sites. The introduction of the Nb^(5+) ions produces some extra free-electrons. These electrons recombine with the carriers of the system. It makes the mobility and the Hall number of YBa_2Cu_(3-x)Nb_xO_(7-y) decrease and also result in a depression in Tc.
文摘Radiotherapy for Brain Metastases Brain metastases are common in patients with malignant tumors.According to the reports from autopsy,surgery and imaging investigations,the incidence of brain metastases is approximately 20%~40%[1].The main symptoms are headache,dementia and motor dysfunction.The most common primary sites are lung,breast,colorectal,melanoma and kidney.
基金The first author is supported by the Key Project of Chinese Ministry of Education(Grant No.211162)Sichuan Province Science Foundation for Youths(Grant No.2012JQ0011)the second author is supported byNational Natural Science Foundation of China(Grant No.11371267)
文摘The instability property of the standing wave uω（t, x） = eiωtφ（x） for the Klein–Gordon– Hartree equation is investigated. For the case N≥3 and w2 〈2/N＋4-γ,it is shown that the standing wave eiwtφ（x） is strongly unstable by blow-up in finite time.
文摘本文研究方程驻波的强不稳定性iut＋△u＋a｜u｜p-1u＋E1（｜u｜2）u=0，t≥0，z∈Rn，其中a〉0，1〈p〈n＋2/（n-2）＋,n∈{2，3}，当1＋4/n≤p〈n＋2/（n-2）＋时，文[Sharpthreshold of global existence and instability of standing wave for a Davey-Stewartsonsystem, Commun. Math. Phys., 2008, 283：93 125]在驻波的频率满足一定假设条件下，证明了此方程驻波的强不稳定性．本文去掉这个假设，得到相同的结论．
