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991.
We analyze correlation functions of Wilson loop observables and local vertex operators within the strong-coupling regime of the AdS/CFT correspondence. When the local operator corresponds to a light string state with finite conserved charges the correlation function can be evaluated in the semiclassical approximation of large string tension, where the contribution from the light vertex can be neglected. We consider the cases where the Wilson loops are described by two concentric surfaces and the local vertices are the superconformal chiral primary scalar or a singlet massive scalar operator. 相似文献
992.
993.
Juan J. Pantrigo Rafael Martí Abraham Duarte Eduardo G. Pardo 《Annals of Operations Research》2012,199(1):285-304
The cutwidth minimization problem consists of finding a linear layout of a graph so that the maximum linear cut of edges is minimized. This NP-hard problem has applications in network scheduling, automatic graph drawing and information retrieval. We propose a heuristic method based on the Scatter Search (SS) methodology for finding approximate solutions to this optimization problem. This metaheuristic explores solution space by evolving a set of reference points. Our SS method is based on a GRASP constructive algorithm, a local search strategy based on insertion moves and voting-based combination methods. We also introduce a new measure to control the diversity in the search process. Empirical results with 252 previously reported instances indicate that the proposed procedure compares favorably to previous metaheuristics for this problem, such as Simulated Annealing and Evolutionary Path Relinking. 相似文献
994.
The problem of designing high speed networks using different modules of link capacities, in the same model, in order to meet uncertain demands obtained from different probability distribution functions (PDF) is a very hard and challenging real network design problem. The novelty of the new model, compared to previous ones, is to allow installing more than one module per link having equal or different capacities. Moreover, the scenarios of traffic can be generated, according to practical observations, from the main classes of uncertain demands (multi-service) simulated from different PDFs, including heavy tailed ones. These classes of traffic are considered simultaneously for the scenario generation, different from related works in the literature that use only one probability distribution function to simulate the scenarios of traffic. In this work we present the problem formulation and report computational results using branch-and-bound and L-shaped decomposition solution approaches. We consider in the same model up to three different types of modular capacities (multi-facility), since it seems that using more than this can lead to an intractable model. The objective is to minimize penalty (in case of unmet demands) and investment costs. We obtain confidence intervals (with 95% of covering rate) on the expected optimal solution value for the resulting two-stage stochastic integer-modular problem and discuss when they are meaningful. Numerical experiments show that our model can handle up to medium real size instances. 相似文献
995.
We consider Bell tests involving bipartite states shared between three parties. We show that the simple inclusion of a third part may greatly simplify the measurement scenario (in terms of the number of measurement settings per part) and allows the identification of previously unknown nonlocal resources. 相似文献
996.
Gómez-Alcalá R Fraile-Peláez FJ Chamorro-Posada P Díaz-Otero FJ 《Optics letters》2012,37(11):2097-2099
In this Letter we employ the general coupled-mode equations of the nonlinear directional coupler and demonstrate that the switching characteristics of prototypical nonlinear racetrack-resonator structures may differ considerably from those obtained when the standard, generally incorrect, coupled-mode equations are used. 相似文献
997.
Rafael Silva 《Applied Surface Science》2009,255(12):6345-6354
Surface modifying strategies were developed to immobilize PAA cross-linked layers (hydrogel layers) with different thicknesses by chemical binding to the surface of polyethylene (PE). Polyethylene films were functionalized by two methods, chromic acid oxidation and maleic anhydride grafting. The reaction of the functional groups placed onto the film surface with ethylenediamine promoted the formation of an amine-functionalized surface. The thickness of the hydrogel layer was correlated with the presence and the release of impregnated ethylenediamine during the immobilization of the PAA chains by thermal esterification. Ethylenediamine acts as a cross-linking agent between different PAA chains. Attenuated total reflectance (ATR) FTIR spectroscopy and scanning electron microscopy (SEM) were used to characterize the chemical composition and the morphologies of the modified film surface. 相似文献
998.
Ricardo Baggio Nieves M. C. Casado Rafael Calvo Raul E. Rapp María Teresa Garland 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(5):m250-m252
In the title compound, [Cu(C15H20N2O4)]n, the copper(II) coordination is square planar. The anionic l ‐tyrosyl‐l ‐leucinate ligand binds in an N,N′,O‐tridentate mode to one CuII cation on one side and in an O‐monodentate mode to a second CuII cation on the other side, thus defining –Cu—O—C—O—Cu′– chains which run along the a axis. These chains are held together by a strong hydrogen bond involving the hydroxy H atom. 相似文献
999.
1000.
In the present work, a simple and fast methodology has been developed for the analysis of chlorotoluenes in water samples using solid-phase microextraction (SPME) coupled to gas chromatography-tandem mass spectrometry (GC/MS/MS). A multifactorial experimental design strategy was used for studying the influence on extraction yield of factors such as fiber coating, extraction mode, temperature, and addition of sodium chloride. Quantitative recoveries (>/=84%) and satisfactory precision (relative standard deviations (RSD)=12%) have been obtained. Limits of detection (LODs) in the sub-picogram per litre level from 0.030 to 0.330 were achieved for all analyzed compounds. Linearity was studied in a wide range of concentrations and an analysis of variance with a lack-of-fit test was run to validate the calibration data. Extraction time profiles were also studied, showing that most of chlorotoluenes reached the equilibrium or were close to it. Finally, the applicability of the proposed method has been demonstrated for real samples including river and sewage water samples. Since no matrix effects were observed, quantification could readily be carried out by external calibration with ultrapure water standards. 相似文献