633 research outputs found
Electroweak Penguin Contributions in and decays Beyond Leading Logarithms
Using the next-to-leading order low energy effective Hamiltonian for , transitions, the contributions of electroweak
penguin operators in and decays
are estimated in the standard model. We find that, for some channels, the
electroweak penguin effects can enhance or reduce the QCD penguin and/or tree
level contributions by at least , and can even play dominant role.Comment: 12 pages, late
Bichromatic field generation from double-four-wave mixing in a double-electromagnetically induced transparency system
We demonstrate the double electromagnetically induced transparency
(double-EIT) and double four-wave mixing (double-FWM) based on a new scheme of
non-degenerate four-wave mixing (FWM) involving five levels of a cold 85Rb
atomic ensemble, in which the double-EIT windows are used to transmit the probe
field and enhance the third-order nonlinear susceptibility. The phase-matching
conditions for both four-wave mixings could be satisfied simultaneously. The
frequency of one component of the generated bichromatic field is less than the
other by the ground-state hyperfine splitting (3GHz). This specially designed
experimental scheme for simultaneously generating different nonlinear
wave-mixing processes is expected to find applications in quantum information
processing and cross phase modulation. Our results agree well with the
theoretical simulation.Comment: Accepted by NJ
Zhang Neural Networks for Online Solution of Time-Varying Linear Inequalities
In this chapter, a special type of recurrent neural networks termed “Zhang neural network” (ZNN) is presented and studied for online solution of time-varying linear (matrix-vector and matrix) inequalities. Specifically, focusing on solving the time-varying linear matrix-vector inequality (LMVI), we develop and investigate two different ZNN models based on two different Zhang functions (ZFs). Then, being an extension, by defining another two different ZFs, another two ZNN models are developed and investigated to solve the time-varying linear matrix inequality (LMI). For such ZNN models, theoretical results and analyses are presented as well to show their computational performances. Simulation results with two illustrative examples further substantiate the efficacy of the presented ZNN models for time-varying LMVI and LMI solving
2-Iodo-3-methoxy-6-methylpyridine
The title compound, C7H8INO, which crystallizes with three independent molecules in the asymmetric unit, was prepared by the reaction of 3-methoxy-6-methylpyridine with KI and I2 in tetrahydrofuran solution. In the crystal structure, the three independent molecules are arranged in a similar orientation with the three polar methoxy groups aligned on one side and the three non-polar methyl groups on the other side. The three molecules, excluding methyl H atoms, are essentially planar, with r.m.s. deviations of 0.0141 (1), 0.0081 (1) and 0.0066 (2)Å. The three pyridine rings make dihedral angles of 58.09 (3) 66.64 (4) and 71.5 (3)°. The crystal structure features rather weak intermolecular C—H⋯O hydrogen bonds, which link two molecules into dimers, and short I⋯N contacts [4.046 (3) Å]
Analysis of the Decays B-> \pi \pi and \pi K with QCD Factorization in the Heavy Quark Limit
In this work, we calculate the branching ratios and CP asymmetries of the
decays of and in the frame of QCD factorization in the
heavy quark limit. We also compare the results with the estimates by using
conventional factorization and experimental measurements.Comment: RevTeX, 14 pages including 5 eps figure
Characteristics of the Tan-Lu Strike-Slip Fault and Its Controls on Hydrocarbon Accumulation in the Liaodong Bay Sub-Basin, Bohai Bay Basin, China
The Tan-Lu Fault, one of the major strike-slip structures in China, controlled the development of most of the Meso-Cenozoic NNE trend rifted petroliferous basins in east China. It has cut across the Bohai Bay Basin since the late Cenozoic and played an important role in hydrocarbon accumulation and distribution in the Liaodong Bay sub-basin of the Bohai Bay Basin. The purpose of this paper is to study the geometry of the Tan-Lu strike-slip and how it affected petroleum system development in the Liaodong Bay sub-basin. The innovative seismic interpretation revealed the western branch of the Tan-Lu strike-slip fault cut through the Liaozhong depression of the sub-basin and its eastern branch superimposed on the earlier extensional boundary fault of the sub-basin. The strike-slip movement is characterized by a distinctive strike-slip zone associated with the NE en echelon faults in the central part of the Liaozhong depression and also caused the formation of the Liaodong uplift and the Liaodong depression in the east Liaodong Bay Sub-basin. Rapid movement of the Tan-Lu strike-slip fault has deepened the Liaozhong depression and facilitated the maturation of source rock. Related fault movement formed a series of structural traps and paleotopographic highs and lows that subsequently controlled sediment dispersal and the distribution of stratigraphic-related traps within sequence stratigraphic framework. Exploration practice, geochemical study and petroleum system modeling demonstrate that the Tan-Lu strike-slip and its associated faults acted as good hydrocarbon migration pathways and hydrocarbon accumulated in many traps associated with the Tan-Lu strike-slip zone. Many recent discoveries along the strike-slip zone prove that the petroleum system in Liaodong Bay Sub-basin was mainly controlled by the activity of the Tan-Lu strike-slip. The resulting hydrocarbon accumulation model in this sub-basin may provide a paradigm for the prediction of hydrocarbon accumulation to other east China basins along the Tan-Lu strike-slip fault zone. Key words: Liaodong Bay Sub-basin; Tan-Lu strike-slip fault; Hydrocarbon accumulation; Petroleum system; Sequence stratigraph
Transcriptional Regulation of opaR, qrr2–4 and aphA by the Master Quorum-Sensing Regulator OpaR in Vibrio parahaemolyticus
Background: Vibrio parahaemolyticus is a leading cause of infectious diarrhea and enterogastritis via the fecal-oral route. V. harveyi is a pathogen of fishes and invertebrates, and has been used as a model for quorum sensing (QS) studies. LuxR is the master QS regulator (MQSR) of V. harveyi, and LuxR-dependent expression of its own gene, qrr2–4 and aphA have been established in V. harveyi. Molecular regulation of target genes by the V. parahaemolyticus MQSR OpaR is still poorly understood. Methodology/Principal Findings: The bioinformatics analysis indicated that V. parahaemolyticus OpaR, V. harveyi LuxR, V. vulnificu SmcR, and V. alginolyticus ValR were extremely conserved, and that these four MQSRs appeared to recognize the same conserved cis-acting signals, which was represented by the consensus constructs manifesting as a position frequency matrix and as a 20 bp box, within their target promoters. The MQSR box-like sequences were found within the upstream DNA regions of opaR, qrr2–4 and aphA in V. parahaemolyticus, and the direct transcriptional regulation of these target genes by OpaR were further confirmed by multiple biochemical experiments including primer extension assay, gel mobility shift assay, and DNase I footprinting analysis. Translation and transcription starts, core promoter elements for sigma factor recognition, Shine-Dalgarno sequences for ribosome recognition, and OpaR-binding sites were determined for the five target genes of OpaR, which gave a structural map of the OpaR-dependent promoters. Further computational promote
Cryo-EM Structure of a Novel Calicivirus, Tulane Virus.
Tulane virus (TV) is a newly isolated cultivatable calicivirus that infects juvenile rhesus macaques. Here we report a 6.3 Å resolution cryo-electron microscopy structure of the TV virion. The TV virion is about 400 Å in diameter and consists of a T = 3 icosahedral protein capsid enclosing the RNA genome. 180 copies of the major capsid protein VP1 (~57 KDa) are organized into two types of dimers A/B and C/C and form a thin, smooth shell studded with 90 dimeric protrusions. The overall capsid organization and the capsid protein fold of TV closely resemble that of other caliciviruses, especially of human Norwalk virus, the prototype human norovirus. These close structural similarities support TV as an attractive surrogate for the non-cultivatable human noroviruses. The most distinctive feature of TV is that its C/C dimers are in a highly flexible conformation with significantly reduced interactions between the shell (S) domain and the protruding (P) domain of VP1. A comparative structural analysis indicated that the P domains of TV C/C dimers were much more flexible than those of other caliciviruses. These observations, combined with previous studies on other caliciviruses, led us to hypothesize that the enhanced flexibility of C/C dimer P domains are likely required for efficient calicivirus-host cell interactions and the consequent uncoating and genome release. Residues in the S-P1 hinge between the S and P domain may play a critical role in the flexibility of P domains of C/C dimers
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