Experimental study on seismic behavior of steel tube confined high-strength concrete shear walls

The high strength concrete shear walls are characterized by its high bearing capacity, high stiffness but a poor deformation capacity. In order to improve the deformation capacity of these members, specimens of high-strength concrete shear wall with steel tube confined boundary elements were designed and the quasi-static tests were conducted. The failure mode, failure mechanism, deformation capacity, hysteretic behavior, stiffness degradation and energy dissipation capacity of specimens were researched. The results indicate that the steel tube boundary elements can provide an effective confinement to the wall pier and the horizontal bearing capacity of specimens dropped slowly. Under a high axial force, the vertical bearing capacity of specimens can be maintained, and the deformation and energy dissipation capacity could be obviously enhanced due to the use of steel tubes in the boundary elements. The ultimate displacement and the energy dissipation of steel tube confined high-strength concrete shear walls were increased by 27 % and 81 % respectively compared to high-strength concrete shear walls with the same axial load ratio. According to the experimental results, the calculation formula is addressed for the cross-section bearing capacity of steel tube confined high-strength concrete shear wall. As a result, it is a good practice that the steel tube confined boundary elements can be utilized at the bottom strengthening zone so as to improve the seismic performance of high-strength concrete shear walls

Phylogenetic analysis of porcine parvoviruses from swine samples in China

<p>Abstract</p> <p>Background</p> <p>Porcine parvovirus (PPV) usually causes reproductive failure in sows. The objective of the present study was to analyze the phylogenetic distribution and perform molecular characterization of PPVs isolated in China, as well as to identify two field strains, LZ and JY. The data used in this study contained the available sequences for NS1 and VP2 from GenBank, as well as the two aforementioned Chinese strains.</p> <p>Results</p> <p>Phylogenetic analysis shows that the PPV sequences are divided into four groups. The early Chinese PPV isolates are Group I viruses, and nearly all of the later Chinese PPV isolates are Group II viruses. LZ belongs to group II, whereas the JY strain is a Group III virus. This is the first report on the isolation of a Group III virus in China. The detection of selective pressures on the PPV genome shows that the NS1 and VP2 genes are under purifying selection and positive selection, respectively. Moreover, the amino acids in the VP2 capsid are highly variable because of the positive selection.</p> <p>Conclusions</p> <p>Our study provides new molecular data on PPV strains in China, and emphasizes the importance of etiological studies of PPV in pigs.</p

Polymorphic genetic characterization of the ORF7 gene of porcine reproductive and respiratory syndrome virus (PRRSV) in China

<p>Abstract</p> <p>Background</p> <p>Porcine reproductive and respiratory syndrome virus (PRRSV) exhibits extensive genetic variation. The outbreak of a highly pathogenic PRRS in 2006 led us to investigate the extent of PRRSV genetic diversity in China. To this end, we analyzed the Nsp2 and ORF7 gene sequences of 98 Chinese PRRSV isolates.</p> <p>Results</p> <p>Preliminary analysis indicated that highly pathogenic PRRSV strains with a 30-amino acid deletion in the Nsp2 protein are the dominant viruses circulating in China. Further analysis based on ORF7 sequences revealed that all Chinese isolates were divided into 5 subgroups, and that the highly pathogenic PRRSVs were distantly related to the MLV or CH-1R vaccine, raising doubts about the efficacy of these vaccines. The ORF7 sequence data also showed no apparent associations between geographic or temporal origin and heterogeneity of PRRSV in China.</p> <p>Conclusion</p> <p>These findings enhance our knowledge of the genetic characteristics of Chinese PRRSV isolates, and may facilitate the development of effective strategies for monitoring and controlling PRRSV in China.</p

In-vitro and in-vivo phenotype of type Asia 1 foot-and-mouth disease viruses utilizing two non-RGD receptor recognition sites

<p>Abstract</p> <p>Background</p> <p>Foot-and-mouth disease virus (FMDV) uses a highly conserved Arg-Gly-Asp (RGD) triplet for attachment to host cells and this motif is believed to be essential for virus viability. Previous sequence analyses of the 1D-encoding region of an FMDV field isolate (Asia1/JS/CHA/05) and its two derivatives indicated that two viruses, which contained an Arg-Asp-Asp (RDD) or an Arg-Ser-Asp (RSD) triplet instead of the RGD integrin recognition motif, were generated serendipitously upon short-term evolution of field isolate in different biological environments. To examine the influence of single amino acid substitutions in the receptor binding site of the RDD-containing FMD viral genome on virus viability and the ability of non-RGD FMDVs to cause disease in susceptible animals, we constructed an RDD-containing FMDV full-length cDNA clone and derived mutant molecules with RGD or RSD receptor recognition motifs. Following transfection of BSR cells with the full-length genome plasmids, the genetically engineered viruses were examined for their infectious potential in cell culture and susceptible animals.</p> <p>Results</p> <p>Amino acid sequence analysis of the 1D-coding region of different derivatives derived from the Asia1/JS/CHA/05 field isolate revealed that the RDD mutants became dominant or achieved population equilibrium with coexistence of the RGD and RSD subpopulations at an early phase of type Asia1 FMDV quasispecies evolution. Furthermore, the RDD and RSD sequences remained genetically stable for at least 20 passages. Using reverse genetics, the RDD-, RSD-, and RGD-containing FMD viruses were rescued from full-length cDNA clones, and single amino acid substitution in RDD-containing FMD viral genome did not affect virus viability. The genetically engineered viruses replicated stably in BHK-21 cells and had similar growth properties to the parental virus. The RDD parental virus and two non-RGD recombinant viruses were virulent to pigs and bovines that developed typical clinical disease and viremia.</p> <p>Conclusions</p> <p>FMDV quasispecies evolving in a different biological environment gained the capability of selecting different receptor recognition site. The RDD-containing FMD viral genome can accommodate substitutions in the receptor binding site without additional changes in the capsid. The viruses expressing non-RGD receptor binding sites can replicate stably in vitro and produce typical FMD clinical disease in susceptible animals.</p

A STUDY ON DYNAMIC RESPONSE OF A CURVED VIADUCT SYSTEM WITH INTEGRATED SLIDING BEARING IN CONSIDERATION OF THE DIRECTION OF EARTHQUAKE

The Thirteenth East Asia-Pacific Conference on Structural Engineering and Construction (EASEC-13), September 11-13, 2013, Sapporo, Japan

Weighted-elite-memory mechanism enhances cooperation in social dilemmas

The issue of how to enhance cooperation has been a hot topic of research in evolutionary games for a long time. A mechanism is proposed to facilitate the cooperation behavior of evolutionary groups on networks in three game models, including prisoner's dilemma, snowdrift game, and stag hunt game. The core of the mechanism lies in: 1) Each player has a length of memory and uses the information of the elite in the memory span to update its strategy. 2) Each player has the chance to game with a certain neighbor more than once in each round. 3) The accumulative payoff of a player consists of two parts, one from playing with elites in memory length and another from playing with current neighbors, and a weight is introduced to adjust these two parts. The findings of the simulation demonstrate that a small weight can significantly enhance cooperation in three typical social dilemmas. Furthermore, the level of cooperation increases at first and then stays stable as the memory length increases