5,612 research outputs found
Boekbespreking van: De geschade heerlijkheid: Politiek gedrag van vrouwen en mannen, 1918-1988
Expression of complementary RNA from chloroplast transgenes affects editing efficiency of transgene and endogenous chloroplast transcripts
The expression of angiosperm chloroplast genes is modified by C-to-U RNA editing. The mechanism for recognition of the ∼30 C targets of editing is not understood. There is no single consensus sequence surrounding editing sites, though sites can be grouped into small ‘clusters’ of two to five sites exhibiting some sequence similarity. While complementary RNA that guides nucleotides for alteration has been detected in other RNA modification systems, it is not known whether complementary RNA is involved in chloroplast editing site recognition. We investigated the effect of expressing RNA antisense to the sequences −20 to +6 surrounding the RpoB-2 C target of editing, which is a member of a cluster that includes the PsbL-1 and Rps14-1 sites. Previous experiments had shown that chloroplast rpoB transgene transcripts carrying only these 27 nt were edited in vivo at the proper C. Though transcripts carrying sequences −31 to +60 surrounding the RpoB-2 sites were edited in chloroplast transgenic plants, transcripts carrying the −31 to +62 region followed by the 27 nt complementary region were not edited at all. In contrast, a similar construct, in which the C target as well as the preceding and subsequent nucleotides were mismatched within the 27 nt region, was efficiently edited. The presence of any of the four transgenes carrying RpoB-2 sequences in sense and/or antisense orientation resulted in reduced editing at the PsbL-1 site. Chloroplast transgenic plants expressing the three different antisense RNA constructs exhibited abnormal growth and development, though plants expressing the 92 nt sense transcripts were phenotypically normal
Distributed Testing of Excluded Subgraphs
We study property testing in the context of distributed computing, under the
classical CONGEST model. It is known that testing whether a graph is
triangle-free can be done in a constant number of rounds, where the constant
depends on how far the input graph is from being triangle-free. We show that,
for every connected 4-node graph H, testing whether a graph is H-free can be
done in a constant number of rounds too. The constant also depends on how far
the input graph is from being H-free, and the dependence is identical to the
one in the case of testing triangles. Hence, in particular, testing whether a
graph is K_4-free, and testing whether a graph is C_4-free can be done in a
constant number of rounds (where K_k denotes the k-node clique, and C_k denotes
the k-node cycle). On the other hand, we show that testing K_k-freeness and
C_k-freeness for k>4 appear to be much harder. Specifically, we investigate two
natural types of generic algorithms for testing H-freeness, called DFS tester
and BFS tester. The latter captures the previously known algorithm to test the
presence of triangles, while the former captures our generic algorithm to test
the presence of a 4-node graph pattern H. We prove that both DFS and BFS
testers fail to test K_k-freeness and C_k-freeness in a constant number of
rounds for k>4
Integrated Analysis of Production Potential and Profitability of a Horizontal Well in the Lower Glen Rose Formation, Maverick County, Texas
The U.S. Department of Energy/Morgantown Energy Technology Center (DOE/METC) awarded a contract in 1991 to Prime Energy Corporation (PEC) to demonstrate the benefit of using horizontal wells to recover gas from low permeability formations. The project area was located in the Chittim field of Maverick County, Texas. The Lower Glen Rose Formation in the Chittim field was a promising horizontal well candidate based on the heterogenous nature of the reservoir (suggested by large well-to-well variances in reserves) and the low percentage of economical vertical wells. Since there was substantial evidence of reservoir heterogeneity, it was unknown whether the selected, wellsite would penetrate a reservoir with the desired properties for a horizontal well. Thus, an integrated team was formed to combine geologic analysis, seismic interpretation, reservoir engineering, reservoir simulation, and economic assessment to analyze the production potential and profitability of completing a horizontal well in the Lower Glen Rose formation
Search for Higgs boson production in dilepton and missing energy final states with 5.4 fb-1 of pp- collisions at Sqrt s=1.96 TeV
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