Robust Chattering-Free Finite Time Attitude Tracking Control with Input Saturation

This paper addresses the attitude tracking control problem of a rigid spacecraft in the presence of the modeling uncertainty, external disturbance, and saturated control input by designing two robust attitude tracking controllers. The basic controller is formulated using an integral sliding mode surface which is continuous and provides an asymptotic convergence rate for the closed-loop system. In this case, only the external disturbance with the prior information is considered. Then, to provide a finite time convergence rate and further improve the robustness of the control system under the unknown system uncertainty containing both the modeling uncertainty and external disturbance,a novel integral terminal sliding mode surface(ITSMS) is designed and associated with the continuous adaptive control method. Besides, a command filter is utilized to deal with the immeasurability problem within the proposed ITSMS and an auxiliary system to counteract the input saturation problem. Digital simulations are presented to verify the effectiveness of the proposed controllers.     

Act in contravention: a non-planar coupled electrode design utilizing "tip effect" for ultra-high areal capacity,long cycle life zinc-based batteries

Aqueous zinc-based batteries (ZBBs) have great potential as commercial energy storage devices.However,the poor cycling stability of zinc anode under high areal ...     

Structure and function of Zika virus NS5 protein: perspectives for drug design

Zika virus (ZIKV) belongs to the positive-sense single-stranded RNA-containing Flaviviridae family. Its recent outbreak and association with human diseases (e.g. neurological disorders) have raised global health concerns, and an urgency to develop a therapeutic strategy against ZIKV infection. However, there is no currently approved antiviral against ZIKV. Here we present a comprehensive overview on recent progress in structure–function investigation of ZIKV NS5 protein, the largest non-structural protein of ZIKV, which is responsible for replication of the viral genome, RNA capping and suppression of host interferon responses. Structural comparison of the N-terminal methyltransferase domain and C-terminal RNA-dependent RNA polymerase domain of ZIKV NS5 with their counterparts from related viruses provides mechanistic insights into ZIKV NS5-mediated RNA replication, and identifies residues critical for its enzymatic activities. Finally, a collection of recently identified small molecule inhibitors against ZIKV NS5 or its closely related flavivirus homologues are also discussed.     

Differentiated cells are more efficient than adult stem cells for cloning by somatic cell nuclear transfer

Since the creation of Dolly via somatic cell nuclear transfer (SCNT), more than a dozen species of mammals have been cloned using this technology. One hypothesis for the limited success of cloning via SCNT (1%-5%) is that the clones are likely to be derived from adult stem cells. Support for this hypothesis comes from the findings that the reproductive cloning efficiency for embryonic stem cells is five to ten times higher than that for somatic cells as donors and that cloned pups cannot be produced directly from cloned embryos derived from differentiated B and T cells or neuronal cells. The question remains as to whether SCNT-derived animal clones can be derived from truly differentiated somatic cells. We tested this hypothesis with mouse hematopoietic cells at different differentiation stages: hematopoietic stem cells, progenitor cells and granulocytes. We found that cloning efficiency increases over the differentiation hierarchy, and terminally differentiated postmitotic granulocytes yield cloned pups with the greatest cloning efficiency.     

Epigenetic remodeling in colorectal cancer results in coordinate gene suppression across an entire chromosome band

We report a new mechanism in carcinogenesis involving coordinate long-range epigenetic gene silencing. Epigenetic silencing in cancer has always been envisaged as a local event silencing discrete genes. However, in this study of silencing in colorectal cancer, we found common repression of the entire 4-Mb band of chromosome 2q.14.2, associated with global methylation of histone H3 Lys9. DNA hypermethylation within the repressed genomic neighborhood was localized to three separate enriched CpG island 'suburbs', with the largest hypermethylated suburb spanning 1 Mb. These data change our understanding of epigenetic gene silencing in cancer cells: namely, epigenetic silencing can span large regions of the chromosome, and both DNA-methylated and neighboring unmethylated genes can be coordinately suppressed by global changes in histone modification. We propose that loss of gene expression can occur through long-range epigenetic silencing, with similar implications as loss of heterozygosity in cancer.     

Male-pattern baldness susceptibility locus at 20p11

We conducted a genome-wide association study for androgenic alopecia in 1,125 men and identified a newly associated locus at chromosome 20p11.22, confirmed in three independent cohorts (n = 1,650; OR = 1.60, P = 1.1 x 10(-14) for rs1160312). The one man in seven who harbors risk alleles at both 20p11.22 and AR (encoding the androgen receptor) has a sevenfold-increased odds of androgenic alopecia (OR = 7.12, P = 3.7 x 10(-15)).     

MicroRNA Mirn140 modulates Pdgf signaling during palatogenesis

Disruption of signaling pathways such as those mediated by sonic hedgehog (Shh) or platelet-derived growth factor (Pdgf) causes craniofacial abnormalities, including cleft palate. The role that microRNAs play in modulating palatogenesis, however, is completely unknown. We show that, in zebrafish, the microRNA Mirn140 negatively regulates Pdgf signaling during palatal development, and we provide a mechanism for how disruption of Pdgf signaling causes palatal clefting. The pdgf receptor alpha (pdgfra) 3' UTR contained a Mirn140 binding site functioning in the negative regulation of Pdgfra protein levels in vivo. pdgfra mutants and Mirn140-injected embryos shared a range of facial defects, including clefting of the crest-derived cartilages that develop in the roof of the larval mouth. Concomitantly, the oral ectoderm beneath where these cartilages develop lost pitx2 and shha expression. Mirn140 modulated Pdgf-mediated attraction of cranial neural crest cells to the oral ectoderm, where crest-derived signals were necessary for oral ectodermal gene expression. Mirn140 loss of function elevated Pdgfra protein levels, altered palatal shape and caused neural crest cells to accumulate around the optic stalk, a source of the ligand Pdgfaa. These results suggest that the conserved regulatory interactions of mirn140 and pdgfra define an ancient mechanism of palatogenesis, and they provide candidate genes for cleft palate.     

Yersinia pestis genome sequencing identifies patterns of global phylogenetic diversity

Plague is a pandemic human invasive disease caused by the bacterial agent Yersinia pestis. We here report a comparison of 17 whole genomes of Y. pestis isolates from global sources. We also screened a global collection of 286 Y. pestis isolates for 933 SNPs using Sequenom MassArray SNP typing. We conducted phylogenetic analyses on this sequence variation dataset, assigned isolates to populations based on maximum parsimony and, from these results, made inferences regarding historical transmission routes. Our phylogenetic analysis suggests that Y. pestis evolved in or near China and spread through multiple radiations to Europe, South America, Africa and Southeast Asia, leading to country-specific lineages that can be traced by lineage-specific SNPs. All 626 current isolates from the United States reflect one radiation, and 82 isolates from Madagascar represent a second radiation. Subsequent local microevolution of Y. pestis is marked by sequential, geographically specific SNPs.     

基于专利引文数据的混合动力汽车创新扩散研究

以巴斯扩散模型为理论基础,利用1995～2011年的专利引文数据,对混合动力汽车的技术扩散模型进行了非线性最小二乘法估计。结果显示：①各参数均为统计上显著的,且可决系数与调整可决系数均较大;②该技术的扩散路径符合巴斯模型,且处于成熟阶段。同时,以普锐斯为例,对其1997～2010年的销售数据进行拟合与预测,结果显示,该产品的扩散过程符合巴斯模型。文章认为新技术的扩散与新产品之间存在时滞。     

Multispecies-compatible antitumor effects of a cross-species small-interfering RNA against mammalian target of rapamycin

Successful development of sequence-specific siRNA (small interfering RNA)-based drugs requires an siRNA design that functions consistently in different organisms. Utilizing the CAPSID program previously developed by our group, we here designed siRNAs against mammalian target of rapamycin (mTOR) that are entirely complementary among various species and investigated their multispecies-compatible gene-silencing properties. The mTOR siRNAs markedly reduced mTOR expression at both the mRNA and protein levels in human, mouse, and monkey cell lines. The reduction in mTOR expression resulted in inactivation of both mTOR complex I and II signaling pathways, as confirmed by reduced phosphorylation of p70S6K (70-kDa ribosomal protein S6 kinase), 4EBP1 (eIF4E-binding protein 1), and AKT, and nuclear accumulation of FOXO1 (forkhead box O1), with consequent cell-cycle arrest, proliferation inhibition, and autophagy activation. Moreover, interfering with mTOR activity in vivo using mTOR small-hairpin RNA-expressing recombinant adeno-associated virus led to significant antitumor effects in xenograft and allograft models. Thus, the present study demonstrates that cross-species siRNA successfully silences its target and readily produces multispecies-compatible phenotypic alterations-antitumor effects in the case of mTOR siRNA. Application of cross-species siRNA should greatly facilitate the development of siRNA-based therapeutic agents.