A pseudo-spectral method for simulating of poro-elastic seismic wave propagation in complex borehole environments

We present a novel numerical approach for the comprehensive, flexible, and accurate simulation of poro-elastic wave propagation in cylindrical coordinates. An important application of this method is the modeling of complex seismic wave phenomena in fluid-filled boreholes, which represents a major, and as of yet largely unresolved, computational problem in exploration geophysics. In view of this, we consider a numerical mesh consisting of three concentric domains representing the borehole fluid in the center, the borehole casing and the surrounding porous formation. The spatial discretization is based on a Chebyshev expansion in the radial direction, Fourier expansions in the other directions, and a Runge-Kutta integration scheme for the time evolution. A domain decomposition method based on the method of characteristics is used to match the boundary conditions at the fluid/porous-solid and porous-solid/porous-solid interfaces. The viability and accuracy of the proposed method has been tested and verified in 2D polar coordinates through comparisons with analytical solutions as well as with the results obtained with a corresponding, previously published, and independently benchmarked solution for 2D Cartesian coordinates. The proposed numerical solution also satisfies the reciprocity theorem, which indicates that the inherent singularity associated with the origin of the polar coordinate system is handled adequately.

Assembly and disassembly of the Golgi Complex: two prodesses arranged in a cis to trans direction

We have studied the disassembly and assembly of two morphologically and functionally distinct parts of the Golgi complex, the cis/middle and trans cisterna/trans network compartments. For this purpose we have followed the redistribution of three cis/middle- (GMPc-1, GMPc-2, MG 160) and two trans- (GMPt-1 and GMPt-2) Golgi membrane proteins during and after treatment of normal rat kidney (NRK) cells with brefeldin A (BFA). BFA induced complete disassembly of the cis/middle- and trans-Golgi complex and translocation of GMPc and GMPt to the ER. Cells treated for short times (3 min) with BFA showed extensive disorganization of both cis/middle- and trans-Golgi complexes. However, complete disorganization of the trans part required much longer incubations with the drug. Upon removal of BFA the Golgi complex was reassembled by a process consisting of three steps: (a) exist of cis/middle proteins from the ER and their accumulation into vesicular structures scattered throughout the cytoplasm; (b) gradual relocation and accumulation of the trans proteins in the vesicles containing the cis/middle proteins; and (c) assembly of the cisternae, and reconstruction of the Golgi complex within an area located in the vicinity of the centrosome from which the ER was excluded. Reconstruction of the cis/middle-Golgi complex occurred under temperature conditions inhibitory of the reorganization of the trans-Golgi complex, and was dependent on microtubules. Reconstruction of the trans-Golgi complex, disrupted with nocodazole after selective fusion of the cis/middle-Golgi complex with the ER, occurred after the release of cis/middle-Golgi proteins from the ER and the assembly of the cis/middle cisternae.

Infrastructure Plan for Iowas's Future Economy: A Strategic Direction

This plan makes 25 recommendations that, when takes together, will take Iowa's infrastructure to the next level, ensure quality of life, and allow the economy to be globally competitive. It requires two fundamental changes in Iowans' prectices: cooperative planning and integration of infrastructure sectors.