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111.
The status of the unitary triangle beyond the standard model including the most recent results on Deltam[s] on dilepton asymmetries and on width differences is presented. Even allowing for general new physics loop contributions the unitarity triangle must be very close to the standard model result. With the new measurements from the Fermilab Tevatron, we obtain for the first time a significant constraint on new physics in the Bs sector. We present the allowed ranges of new physics contributions to DeltaF=2 processes and of the time-dependent CP asymmetry in Bs-->J/psivarphi decays.  相似文献   
112.
113.
An efficient total synthesis of the natural alkaloid (+)-dumetorine by using flow technology is described. The process entailed five separate steps starting from the enantiopure (S)-2-(piperidin-2-yl)ethanol 4 with 29% overall yield. Most of the reactions were carried out by exploiting solvent superheating and by using packed columns of immobilized reagents or scavengers to minimize handling. New protocols for performing classical reactions under continuous flow are disclosed: the ring-closing metathesis reaction with a novel polyethylene glycol-supported Hoveyda catalyst and the unprecedented flow deprotection/Eschweiler-Clarke methylation sequence. The new protocols developed for the synthesis of (+)-dumetorine were applied to the synthesis of its simplified natural congeners (-)-sedamine and (+)-sedridine.  相似文献   
114.
    
The homopolymerization of methyl methacrylate was investigated with bis(salicylaldiminate)nickel(II) complexes, such as bis[3,5‐dinitro‐N(2,6‐diisopropylphenyl)salicylaldiminate]nickel(II) ( IIIa ) and bis[3,5‐dinitro‐N(phenyl)salicylaldiminate]nickel(II) ( IIIb ), and with methylaluminoxane (MAO) as an activator. In particular, the effect of the Al/Ni molar ratio on the catalytic activity and on the properties of the resulting poly(methyl methacrylate) (PMMA) was checked. The maximum activity was ascertained when an Al/Ni molar ratio equal to about 100 was used. However, the productivity of the catalytic systems was rather low. When the IIIa /MAO catalytic system was prepared under an ethylene atmosphere, an extremely high activity was observed, a productivity value of up to around 150,000 g of PMMA/(mol of Ni × h) being obtained, the highest ever found with nickel‐based catalysts. No appreciable presence of ethylene counits in the polymeric products was also ascertained. When the IIIb /MAO system was used, similar results were found, and high molecular weight PMMAs were obtained, despite the absence of bulky isopropyl substituents in positions ortho and ortho′ to the N‐aryl moiety of the salicylaldiminate ligand. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2117–2124, 2003  相似文献   
115.
    
In this paper we study a discrete Raman laser amplification model given as a Lotka-Volterra system. We show that in an ideal situation, the equations can be written as a Poisson system with boundary conditions using a global change of coordinates. We address the questions of existence and uniqueness of a solution. We deduce numerical schemes for the approximation of the solution that have good stability. https://doi.org/10.1051/m2an:2004022  相似文献   
116.
In this paper, a new double diaphragm shock tube facility for studying the structural response of a circular plate resting on soil, when subjected to a shock wave, is described. The present shock tube has been designed in the framework of a more extensive research program aimed at the investigation of underground tunnel lining under blast and fire conditions. The innovative features of the facility are an end-chamber conceived to investigate soil-structure interaction and a burner equipment to heat the specimen in order to study to what extent thermal damage can affect the transmitted and reflected pressure wave as well as the structural response. Details of the shock tube design, construction and test procedure operations are discussed in the paper. Particular emphasis is placed on the principles that have driven the experimental equipment design choices. Numerical simulations have been performed to assess the ideal shock tube performance in terms of reflected pressure and test time duration as well as to evaluate how far the fire testing situation actually is from that normally used in tunnel design.  相似文献   
117.
Experimental observation of three-color optical quantum correlations   总被引:1,自引:0,他引:1  
Quantum correlations among bright pump, signal, and idler beams produced by an optical parametric oscillator, all with different frequencies, are experimentally demonstrated. We show that the degree of entanglement between signal and idler fields is improved by using information on pump fluctuations. To our knowledge this is the first observation of three-color optical quantum correlations.  相似文献   
118.
We consider Markov processes arising from small random perturbations of non-chaotic dynamical systems. Under rather general conditions we prove that, with large probability, the distance between two arbitrary paths starting close to a same attractor of the unperturbed system decreases exponentially fast in time. The case of paths starting in different basins of attraction is also considered as well as some applications to the analysis of the invariant measure and to elliptic problems with small parameter in front to the second derivatives. The proof is based on a multiscale analysis of the typical trajectories of the Markov process; this analysis is done using techniques involved in the proof of Anderson localization for disordered quantum systems.  相似文献   
119.
The steady state solution of the system of equations consisting of the full Navier-Stokes equations and two turbulence equations has been obtained using a multigrid strategy on unstructured meshes. The flow equations and turbulence equations are solved in a loosely coupled manner. The flow equations are advanced in time using a multistage Runge-Kutta time-stepping scheme with a stability-bound local time step, while the turbulence equations are advanced in a point-implicit scheme with a time step which guarantees stability and positivity. Low-Reynolds-number modifications to the original two-equation model are incorporated in a manner which results in well-behaved equations for arbitrarily small wall distances. A variety of aerodynamic flows are solved, initializing all quantities with uniform freestream values. Rapid and uniform convergence rates for the flow and turbulence equations are observed.  相似文献   
120.
The anthocyanin constituents of thirty samples of Vaccinium myrtillus fruits of various origin were examined by high-performance liquid chromatography. The data, characterized by 15 peaks for each chromatogram, were subjected to principal component analysis in order to reveal differences in the chromatograms. The vector space generated by eigenvector projection produced a clear separation between a group composed of Norwegian and Swedish berries and a group of berries of Italian or Romanian origin. Cyanidin glycosides are highly better represented in all the samples of the first group, while delphinidin glycosides are better represented in the latter.  相似文献   
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