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排序方式: 共有411条查询结果,搜索用时 31 毫秒
91.
We present an organized method to convert between partial derivatives of metrics (functions) and covariant derivatives of curvature tensors (functions) on Kähler manifolds. Basically, it reduces the highly recursive computation in tensor calculus to the enumeration of certain trees with external legs. 相似文献
92.
Zhi‐Chang Liu Dr. Chih‐Hsien Chen Dr. Hsian‐Wen Wang Yen‐Chin Huang Ming‐Jui Kao Tsong‐Shin Lim Prof. Tien‐Yau Luh Prof. 《化学:亚洲杂志》2010,5(6):1425-1438
Polynorbornenes appended with porphyrins containing a range of different linkers are synthesized. The use of bisamidic chiral alanine linkers between the pending porphyrins and the polymeric backbone has been shown to bring the adjacent porphyrin chromophores to more suitable orientation for exciton coupling owing to hydrogen bonding between the adjacent linkers. The hydrogen bonding between the adjacent pendants in these polymers may induce a cooperative effect and therefore render single‐handed helical structures for these polymers. Such a cooperative effect is reflected in the enhancement of FRET efficiencies between zinc–porphyrin and free base porphyrin in random copolymers. 相似文献
93.
High‐affinity aptamers for important signal transduction proteins, i.e. Cdc42‐GTP, p21‐activated kinase1 (PAK1) and MRCK (myotonic dystrophy kinase‐related Cdc42‐binding kinase) α were successfully selected in the low micro‐ to nanomolar range using non‐systematic evolution of ligands by exponential enrichment (SELEX) with at least three orders of magnitude enhancement from their respective bulk affinity of naïve DNA library. In the non‐SELEX procedure, CE was used as a highly efficient affinity method to select aptamers for the desired molecular target through a process that involved repetitive steps of partitioning, known as non‐equilibrium CE of equilibrium mixtures with no PCR amplification between successive steps. Various non‐SELEX conditions including the type, concentration and pH of the run buffer were optimized. Other considerations such as salt composition of selection buffer, protein concentration and sample injection size were also studied for high stringency during selection. After identifying the best enriched aptamer pool, randomly selected clones from the aptamer pool were sequenced to obtain the individual DNA sequences. The dissociation constants (Kd) of these sequences were in the low micromolar to nanomolar range, indicating high affinity to the respective proteins. The best binders were also subjected to sequence alignment to generate a phylogenetic tree. No significant consensus region based on approximately 50 sequences for each protein was observed, suggesting the high efficiency of non‐SELEX for the selection of numerous unique sequences with high selectivity. 相似文献
94.
We study the limit of quasilocal mass defined in [4 and 5] for a family of spacelike 2-surfaces in spacetime. In particular,
we show the limit coincides with the ADM mass at spatial infinity. The limit for coordinate spheres of a boosted slice of
the Schwarzchild solution is computed explicitly and shown to give the expected energy-momentum four-vector. 相似文献
95.
Stereoscopic PIV measurements of a turbulent boundary layer with a large spatial dynamic range 总被引:1,自引:1,他引:0
The flow in a streamwise/wall-normal plane of a turbulent boundary layer at moderate Reynolds number (Re
θ = 2,200) is characterized using two stereo PIV systems just overlapping in the streamwise direction. The aim is to generate
SPIV data for near-wall turbulence with enough spatial dynamic range to resolve most of the coherent structures present in
the flow and to facilitate future comparisons with direct numerical simulations. This is made possibly through the use of
four cameras with large CCD arrays (4,008 px × 2,672 px) and through a rigorous experimental procedure designed to minimize
the impact of measurement noise on the resolution of the small scales. For the first time, both a large field of view [S
x
; S
y
] = [2.6δ; 0.75δ] and a high spatial resolution (with an interrogation window size of 13.6+) have been achieved. The quality of the data is assessed through an analysis of some of the statistical results such as the
mean velocity profile, the rms and the PDF of the fluctuations, and the power spectra. 相似文献
96.
Yau Shu Wong 《计算数学(英文版)》1989,7(2):209-216
Preconditionings have proved to be a powerful technique for accelerating the rate of convergence of an iterative method. This paper, which is concerned with the conjugate gradient algorithm for large matrix computations, investigates an approximate polynomial preconditioning strategy. The method is particularly attractive for implementation on vector computers. 相似文献
97.
Using canonical 1-parameter family of Hermitian connections on the tangent bundle, we provide invariant solutions to the Strominger system on certain complex Lie groups and their quotients. Both flat and non-flat cases are discussed in detail. This paper answers a question proposed by Andreas and Garcia-Fernandez in Comm Math Phys 332(3):1381–1383, 2014. 相似文献
98.
Alexander Elgart László Erdős Benjamin Schlein Horng-Tzer Yau 《Archive for Rational Mechanics and Analysis》2006,179(2):265-283
We consider the dynamics of N boson systems interacting through a pair potential N ?1 V a (x i ?x j ) where V a (x)=a ?3 V(x/a). We denote the solution to the N-particle Schrödinger equation by Ψ N, t . Recall that the Gross-Pitaevskii (GP) equation is a nonlinear Schrödinger equation and the GP hierarchy is an infinite BBGKY hierarchy of equations so that if u t solves the GP equation, then the family of k-particle density matrices solves the GP hierarchy. Under the assumption that a=N ?? for 0<3/5, we prove that as N→∞ the limit points of the k-particle density matrices of Ψ N, t are solutions of the GP hierarchy with the coupling constant in the nonlinear term of the GP equation given by ∫V(x)dx. The uniqueness of the solutions of this hierarchy remains an open question. 相似文献
99.
A sharp polynomial estimate of positive integral points in a 4‐dimensional tetrahedron and a sharp estimate of the Dickman‐de Bruijn function 下载免费PDF全文
The estimate of integral points in right‐angled simplices has many applications in number theory, complex geometry, toric variety and tropical geometry. In [24], [25], [27], the second author and other coworkers gave a sharp upper estimate that counts the number of positive integral points in n dimensional () real right‐angled simplices with vertices whose distance to the origin are at least . A natural problem is how to form a new sharp estimate without the minimal distance assumption. In this paper, we formulate the Number Theoretic Conjecture which is a direct correspondence of the Yau Geometry conjecture. We have proved this conjecture for . This paper gives hope to prove the new conjecture in general. As an application, we give a sharp estimate of the Dickman‐de Bruijn function for . 相似文献
100.