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21.
22.
Harold Rüdiger 《Chemie in Unserer Zeit》1981,15(5):155-162
23.
Peter A. Jacobi Lisa M. Armacost Joseph I. Kravitz Michael J. Martinelli Harold G. Selnick 《Tetrahedron letters》1988,29(52):6865-6868
Bis-acetylenic alcohols of proper design undergo a facile oxy-Cope rearrangement to afford mixtures of E- and Z-enynones. These latter compounds afford methylenecyclopentenones upon enolization and electrocyclic ring closure. 相似文献
24.
We analyze the problem of a quantum computer in a correlated environment protected from decoherence by quantum error correction using a perturbative renormalization group approach. The scaling equation obtained reflects the competition between the dimension of the computer and the scaling dimension of the correlations. For an irrelevant flow, the error probability is reduced to a stochastic form for a long time and/or a large number of qubits; thus, the traditional derivation of the threshold theorem holds for these error models. In this way, the "threshold theorem" of quantum computing is rephrased as a dimensional criterion. 相似文献
25.
Barton RJ Smith KB Vincent HT 《The Journal of the Acoustical Society of America》2011,129(5):2772-2784
The properties of the scattered acoustic vector fields generated by simple spheres illuminated by monotonic continuous wave (CW) plane waves are investigated. Analytical solutions are derived from general acoustic pressure scattering models and analyzed for wave numbers in the resonance region. Of particular interest is the understanding of the characteristics of the scattered acoustic vector field in the near-to-far-field transition region. The separable active and reactive components of the acoustic intensity are used to investigate the structural features of the scattered field components. Numerical results are presented for the near and transition regions for a rigid sphere. A method of mapping nulls in the scattered intensity field components is described. The analysis is then extended to include a simple fluid-filled boundary and finally the evacuated thin-walled shell. Near field acoustic intensity field structures are compared against mechanical material properties of vacuous shells. The ability to extract scattered field features is illustrated with measurements obtained from a recent in-air experiment using an anechoic chamber and acoustic vector sensor probes to measure the scattered acoustic vector field from rigid spheres. 相似文献
26.
The extended Airy kernel describes the space-time correlation functions for the Airy process, which is the limiting process for a polynuclear growth model. The Airy functions themselves are given by integrals in which
the exponents have a cubic singularity, arising from the coalescence of two saddle points in an asymptotic analysis. Pearcey
functions are given by integrals in which the exponents have a quartic singularity, arising from the coalescence of three
saddle points. A corresponding Pearcey kernel appears in a random matrix model and a Brownian motion model for a fixed time. This paper derives an extended Pearcey kernel by scaling the Brownian motion model at several times, and a system of partial differential equations whose solution determines
associated distribution functions. We expect there to be a limiting nonstationary process consisting of infinitely many paths,
which we call the Pearcey process, whose space-time correlation functions are expressible in terms of this extended kernel. 相似文献
27.
John W. Birks Steven D. Gabelnick Harold S. Johnston 《Journal of Molecular Spectroscopy》1975,57(1):23-46
Emission from both the state and the previously unreported state of IF has been observed in the gas phase reaction of I2 with F2 at low pressures. For the state the transition moment and vibrational populations were extracted from the spectra by a least-squares method whereby theoretical band shapes were fit to the experimental data. The effect of flow rates of reactants and Ar on the relative emission from the two electronic states, the effect of pressure on the state, and extinction of emission near 470 nm all favor the population of excited electronic states through a four-center reaction complex, rather than association of F and I atoms.It is argued that there is an avoided curve crossing between the lowest two 3Π0+ states of IF, and that the ground state dissociation energy is 23 229 ± 100 cm?1. The radiative lifetime of the state is estimated to be 10?3 sec and to be much shorter than that of the state. 相似文献
28.
Harold Widom 《Integral Equations and Operator Theory》2007,57(1):133-151
The solution of a problem arising in integrable systems requires sharp asymptotics for the inverses and determinants of truncated
Wiener-Hopf operators, both in the regular case (where the non-truncated Wiener-Hopf operator is invertible) and in singular
cases. This paper treats two cases where the symbol of the Wiener-Hopf operator has Fisher-Hartwig singularities, one double
zero or two simple zeros. We find formulas for the inverse that hold uniformly throughout the underlying interval with very
small error, and formulas for the determinant with very small error. 相似文献
29.
30.
In this paper we study the role of cleavability and divisibility in the topology of generalized ordered (GO-)spaces. We characterize cleavability of a GO-space over the class of metrizable spaces, and over the spaces of irrational and rational numbers. We present a series of examples related to characterizations of cleavability over separable metric spaces and over the space of real numbers. 相似文献