Velocity measurements around non-submerged and submerged spur dykes by means of Large-Scale image velocimetry

Field observations on the surface flow were carried out in a straight reach of the Uji River, Kyoto, Japan. Velocity distributions on the water surface were obtained based on the captured video images by means of the Large-Scale Particle Image Velocimetry (LSPIV) developed by Fujita et al. (3). Flow structures around spur dykes are studied for both non-submerged and submerged cases. It is clearly seen that, for both cases, the dykes work as an additional roughness. Their effect on channel conveyance capacity is estimated in terms of the effective channel width calculated from the velocity distributions. For the non-submerged case the area enclosed by the spur dykes has little contribution to the channel conveyance capacity. Whereas for the submerged case the streamwise velocity is fairly decelerated on the dykes' side due to the drag effect of the dykes themselves. It is also of interest that the maximum velocity filament appears at a different position as the water depth varies in case of the channel with single-side dykes such as studied here. In addition, large-scale boils shedding from the submerged dykes are clearly observed. Their origin and advection mechanisms are also evaluated from the video image. The time period of boils appearing on the water surface is well related with the time calculated by the mean upward velocity and the water depth on the dyke

Development of Defective and Persistent Sendai Virus Vector: A UNIQUE GENE DELIVERY/EXPRESSION SYSTEM IDEAL FOR CELL REPROGRAMMING*

The ectopic expression of transcription factors can reprogram differentiated tissue cells into induced pluripotent stem cells. However, this is a slow and inefficient process, depending on the simultaneous delivery of multiple genes encoding essential reprogramming factors and on their sustained expression in target cells. Moreover, once cell reprogramming is accomplished, these exogenous reprogramming factors should be replaced with their endogenous counterparts for establishing autoregulated pluripotency. Complete and designed removal of the exogenous genes from the reprogrammed cells would be an ideal option for satisfying this latter requisite as well as for minimizing the risk of malignant cell transformation. However, no single gene delivery/expression system has ever been equipped with these contradictory characteristics. Here we report the development of a novel replication-defective and persistent Sendai virus (SeVdp) vector based on a noncytopathic variant virus, which fulfills all of these requirements for cell reprogramming. The SeVdp vector could accommodate up to four exogenous genes, deliver them efficiently into various mammalian cells (including primary tissue cells and human hematopoietic stem cells) and express them stably in the cytoplasm at a prefixed balance. Furthermore, interfering with viral transcription/replication using siRNA could erase the genomic RNA of SeVdp vector from the target cells quickly and thoroughly. A SeVdp vector installed with Oct4/Sox2/Klf4/c-Myc could reprogram mouse primary fibroblasts quite efficiently; ∼1% of the cells were reprogrammed to Nanog-positive induced pluripotent stem cells without chromosomal gene integration. Thus, this SeVdp vector has potential as a tool for advanced cell reprogramming and for stem cell research