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991.
By applying the L2-estimate of the scalar curvature of a Riemannian 3-manifold with a Seiberg–Witten monopole class to a collapsing sequence of metrics, we obtain conditions to be a monopole class on certain 3-manifolds. This also gives a relation between a maximizing sequence of the Yamabe constants and the collapsing on a 3-manifold with a non-torsion monopole class. 相似文献
992.
993.
994.
995.
By referring to theorems of Donaldson and Hitchin, we exhibit a rigorous AdS/CFT-type correspondence between classical 2+1-dimensional vacuum general relativity theory on Σ×R and SO(3) Hitchin theory (regarded as a classical conformal field theory) on the spacelike past boundary Σ, a compact, oriented Riemann surface of genus greater than 1. Within this framework we can interpret the 2+1-dimensional vacuum Einstein equation as a decoupled “dual” version of the two-dimensional SO(3) Hitchin equations. 相似文献
996.
We exhibit a Poisson module restoring a twisted Poincaré duality between Poisson homology and cohomology for the polynomial
algebra endowed with Poisson bracket arising from a uniparametrised quantum affine space. This Poisson module is obtained as the
semiclassical limit of the dualising bimodule for Hochschild homology of the corresponding quantum affine space. As a corollary
we compute the Poisson cohomology of R, and so retrieve a result obtained by direct methods (so completely different from ours) by Monnier.
This research of the first author was supported by a Marie Curie Intra-European Fellowship within the 6th European Community
Framework Programme. The second author was supported by EPSRC Grant EP/D034167/1. 相似文献
997.
We have performed first-principles calculations using full-potential augmented-plane-wave method to investigate the fundamental properties of the Cd1–xZnxTe alloys. The composition dependence of the lattice constant and the bulk modulus have been estimated from total energy calculations. By means of the analytical fitting the band structures in the vicinity of the Brillouin center a complete set of effective electron- and hole-masses have also been derived. In order to further understand the effects of the chemical bonding on the above macroscopic properties we then studied the relaxation behaviors and the changes of the electronic states upon alloying for x=0.25 system. The results presented here yield a general understanding of the fundamental properties for the Cd1–xZnxTe crystals studies. 相似文献
998.
Scaling symmetry of -type Drinfel’d–Sokolov hierarchy is investigated. Applying similarity reduction to the hierarchy, one can obtain the Schlesinger
equation with (n + 1) regular singularities. Especially in the case of n = 3, the hierarchy contains the three-wave resonant system and the similarity reduction gives the generic case of the Painlevé
VI equation. We also discuss Weyl group symmetry of the hierarchy.
相似文献
999.
The B,N-bifunctional catalyst homoboroproline has been applied to a catalytic asymmetric nitroalkene-Michael addition to β-nitrostyrene analogues, showing broad substrate tolerance, high conversions and moderate to good asymmetric induction. The ability of homoboroproline to act as an efficient catalyst based on enamine-formation of the secondary amine, coupled with intramolecular Lewis-acid chelation of the nitro function, in a non-FLP manner, to effect efficient and enantioselective catalysis via a proposed large 10-membered ring transition state is remarkable and reinforced by theoretical calculations. 相似文献
1000.
3d过渡金属修饰是改善石墨烯储氢性能的最有效途径, 但仍存在金属团聚和H2解离导致难以脱附的问题. 提出了B/N掺杂单缺陷石墨烯(BMG/NMG)的策略来避免以上两个问题. 密度泛函理论计算结果表明, N掺杂可以使Sc, Ti, V与石墨烯的结合能提高3~4倍, B掺杂可以将Sc与石墨烯的结合能提高3倍. Sc/BMG和Sc/NMG吸附的第一个H2不会解离. Sc/BMG中Sc吸附5个H2, 平均氢分子结合能为-0.18~-0.43 eV, 并且可以通过在同侧锚定多个Sc原子形成Sc/C3B2五元环增加H2吸附位点. Sc/NMG中每个Sc吸附6个H2, 平均氢分子结合能为-0.17~-0.29 eV, 还可以通过在异侧修饰形成Sc/N3/Sc单元进一步提高储氢能力. 研究结果将为设计基于3d过渡金属修饰碳材料的储氢材料提供理论基础. 相似文献