PERMISSIVENESS OF SELECTED CELL LINES TO EQUINE ARTERITIS VIRUS: ESTABLISHMENT, CHARACTERIZATION, AND SIGNIFICANCE OF PERSISTENT INFECTION IN HELA CELLS

A major goal of this research was to evaluate a variety of cell lines for theirpermissiveness to equine arteritis virus (EAV) infection and then identify the mechanismthat restricts EAV infection in certain cell lines. The cell lines BHK-21, RK-13, andC2C12 were found to support productive infection with EAV strain VBS53, whereasHela, Hep-2, and L-M cell lines exhibited limited susceptibility to infection with thisvirus. In the course of the study, it was found that the Hela cell line became moresusceptible to infection with EAV strain VBS53 after extended serial passage. Therespective cell lines were referred to as Hela High (passage 170-221) and Hela Low(passage 95-115) lines. While the Hela High cell line was more susceptible than the HelaLow cell line, it was still considerably less susceptible than the BHK-21 cell line to EAVinfection. Subsequent studies demonstrated that infection with EAV strain VBS53 wasrestricted at the entry step in Hela, Hep-2, and L-M cell lines.The second major goal of this research was to establish an in vitro model ofpersistent EAV infection using cell culture and then use the persistently infected culturesas a tool to study virus-host cell interactions, and to investigate virus and host cellevolution. Persistent infection was successfully established in the Hela High cell line withthe VBS53 strain of EAV. Properties of the persistently infected Hela High cell line werecharacterized. Virus evolution with respect to virus growth characteristics, ability of thevirus to initiate secondary persistent infection, and genetic changes during persistentEAV infection in Hela cells was investigated. Neutralization phenotypic changes of viruses were observed during the course of persistent EAV infection in Hela cells. Reverse genetics studies identified that amino acid 98 of the GP5 protein is a new neutralization determinant of EAV. Using an in vitro assay, it was found that EAV probably became progressively less virulent during the course of persistent infection in Hela cells. The potential changes in pathogenicity of EAV during persistent infection of Hela cells need to be verified by inoculation of horses

Study on boundary search method for DFM mesh generation

The boundary mesh of the casting model was determined by direct calculation on the triangular facets extracted from the STL file of the 3D model. Then the inner and outer grids of the model were identified by the algorithm in which we named Inner Seed Grid Method. Finally, a program to automatically generate a 3D FDM mesh was compiled. In the paper, a method named Triangle Contraction Search Method (TCSM) was put forward to ensure not losing the boundary grids; while an algorithm to search inner seed grids to identify inner/outer grids of the casting model was also brought forward. Our algorithm was simple, clear and easy to construct program. Three examples for the casting mesh generation testified the validity of the program

Orthrus: A Framework for Implementing Efficient Collective I/O in Multi-core Clusters

Abstract. Optimization of access patterns using collective I/O imposes the overhead of exchanging data between processes. In a multi-core-based cluster the costs of inter-node and intra-node data communication are vastly different, and heterogeneity in the efficiency of data exchange poses both a challenge and an opportunity for implementing efficient collective I/O. The opportunity is to effectively exploit fast intra-node communication. We propose to improve communication locality for greater data exchange efficiency. However, such an effort is at odds with improving access locality for I/O efficiency, which can also be critical to collective-I/O performance. To address this issue we propose a framework, Orthrus, that can accommodate multiple collective-I/O implementations, each optimized for some performance aspects, and dynamically select the best performing one accordingly to current workload and system patterns. We have implemented Orthrus in the ROMIO library. Our experimental results with representative MPI-IO benchmarks on both a small dedicated cluster and a large production HPC system show that Orthrus can significantly improve collective I/O performance under various workloads and system scenarios.