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291.
K. Amos W. Bauhoff I. Morrison S.F. Collins R.S. Henderson B.M. Spicer G.G. Shute V.C. Officer D.W. Devins D.L. Friesel W.P. Jones 《Nuclear Physics A》1984,413(2):255-289
Differential cross sections have been measured for the scattering of 135 MeV protons from 16O and data from the transitions to 13 states (up to 19.5 MeV excitation) have been analysed using microscopic and macroscopic nuclear reaction models. Extensive collective model calculations have been made of the transitions to all natural-parity states. The deformation parameters for the 4p4h rotational band are in good agreement with theoretical models. The inelastic scattering data from the excitation of the negative-parity states have also been analysed in the distorted-wave approximation using microscopic (shell and RPA) models of nuclear structure and with density-dependent two-nucleon t-matrices. For positive-parity states, we report the first shell-model calculation using the complete 2?ω basis space and find that the triplet of 2p2h states (4+, 2+, 0+) around 11 MeV excitation is quite well described by this model, as may be a 1+ state which is observed for the first time by proton scattering from 16O. 相似文献
292.
A complete classification is given for neighborly 4-polytopes with 9 vertices. It is found that there are exactly 23 combinatorial types. 相似文献
293.
Amos Nevo 《Geometriae Dedicata》2003,100(1):187-218
Let G denote a semisimple group, a discrete subgroup, B=G/P the Poisson boundary. Regarding invariants of discrete subgroups we prove, in particular, the following:(1) For any -quasi-invariant measure on B, and any probablity measure on , the norm of the operator () on L
2(B,) is equal to (), where is the unitary representation in L
2(X,), and is the regular representation of .(2) In particular this estimate holds when is Lebesgue measure on B, a Patterson–Sullivan measure, or a -stationary measure, and implies explicit lower bounds for the displacement and Margulis number of (w.r.t. a finite generating set), the dimension of the conformal density, the -entropy of the measure, and Lyapunov exponents of .(3) In particular, when G=PSL2() and is free, the new lower bound of the displacement is somewhat smaller than the Culler–Shalen bound (which requires an additional assumption) and is greater than the standard ball-packing bound.We also prove that ()=G() for any amenable action of G and L
1(G), and conversely, give a spectral criterion for amenability of an action of G under certain natural dynamical conditions. In addition, we establish a uniform lower bound for the -entropy of any measure quasi-invariant under the action of a group with property T, and use this fact to construct an interesting class of actions of such groups, related to 'virtual' maximal parabolic subgroups. Most of the results hold in fact in greater generality, and apply for instance when G is any semi-simple algebraic group, or when is any word-hyperbolic group, acting on their Poisson boundary, for example. 相似文献
294.
We extend results of Szeg (1924) and Kappert (1996) on the location of the zeros of the normalized partial sums of cos(z) and sin(z), and their rates of convergence to the associated Szeg curves. 相似文献
295.
Amos Harpaz 《International Journal of Theoretical Physics》2007,46(3):430-436
The role of the characteristic length that characterizes linear acceleration is studied, in order to find how does this length
determine the characteristic wavelength of the radiation created by the accelerated charge. Unruh equation for the temperature
observed by a detector accelerated relative to the vacuum is used to determine the wavelength distribution of the radiation
emitted by a linearly accelerated charge, and it is found that this distribution is peaked close to the characteristic length
that characterizes the linear acceleration, which is the radius of curvature of the curved electric field created by the acelerated
charge.
PACS numbers: 11.10; 41.60.m. 相似文献
296.
An enhanced spiroketalization maneuver permitting equilibration at both the C(8) and C(11) centers of spiroketals 17a,b leads to a more concise and efficient synthesis of phyllanthocin (i.e., 21 steps, 5.6% overall yield). 相似文献
297.
Various methods are suggested for improving the spin densities obtained from unrestricted Harterr—Fock wavefunctions. One is purely empirical and is easy to apply; the others are non-empirical and, while rather more difficult to apply, nevertheless require relatively little computation. 相似文献
298.
299.
The Synthesis and Biological Evaluation of Desepoxyisotedanolide and a Comparison with Desepoxytedanolide 下载免费PDF全文
Arun Naini Dr. Yazh Muthukumar Dr. Aruna Raja Dr. Raimo Franke Ian Harrier Prof. Dr. Amos B. Smith III Prof. Dr. Dongjoo Lee Prof. Dr. Richard E. Taylor Dr. Florenz Sasse Prof. Dr. Markus Kalesse 《Angewandte Chemie (International ed. in English)》2015,54(23):6935-6939
The tedanolides are biologically active polyketides that exhibit a macrolactone constructed from a primary alcohol. Since polyketidal transformations only generate secondary alcohols, it has been hypothesized by Taylor that this unique lactone could arise from a postketidal transesterification. In order to probe this hypothesis and to investigate the biological profile of the putative precursor of all members of the tedanolide family, we embarked on the synthesis of desepoxyisotedanolide and its biological evaluation in comparison to desepoxytedanolide. The biological experiments unraveled a second target for desepoxytedanolide and provided evidence that the proposed transesterification indeed provides a survival advantage for the producing microorganism. 相似文献
300.
Optical pulse amplification in doped fibers is studied using an extended power transport equation for the coupled pulse spectral components. This equation includes the effects of gain saturation, gain dispersion, fiber dispersion, fiber nonlinearity, and amplified spontaneous emission. The new model is employed to study nonlinear gain-induced effects on the spectrotemporal characteristics of amplified subpicosecond pulses, in both the anomalous and the normal dispersion regimes. 相似文献