899 resultados para Generation of 1898
Resumo:
We suggest a scheme to generate a macroscopic superposition state ("Schrodinger cat state") of a free-propagating optical field using a beam splitter, homodyne measurement, and a very small Kerr nonlinear effect. Our scheme makes it possible to reduce considerably the required nonlinear effect to generate an optical cat state using simple and efficient optical elements.
Resumo:
In the present work we consider two aspects of the deposition of metal clusters on an electrode surface. The formation of such clusters with the tip of a scanning tunneling microscope is simulated by atom dynamics. Subsequently the stability of these clusters is investigated by Monte Carlo simulations in a grand-canonical ensemble. In particular, the following systems were considered explicitly: Pd clusters on Au(111), Cu on Au(111), Ag on Au(111), Pb on Au(111) and Cu on Ag(111). The analysis of the results obtained for the different systems leads to the conclusion that optimal systems for nanostructuring are those where the metals participating have similar cohesive energies and negative heats of alloy formation. In this respect, the system Cu-Pd(111) is predicted as a good candidate for the formation of stable clusters. (c) 2005 Elsevier B.V. All rights reserved.
Resumo:
Palladium clusters have been deposited on the surface of a Au(111) electrode with the tip of a scanning tunnelling microscope. The distance over which the tip was moved towards the surface has a decisive influence on the properties of the clusters: the larger this distance, the larger the generated clusters, and the more stable they are. These findings are supported by computer simulations, which further suggest that the larger clusters contain a sizable amount of gold, which enhances their stability. Dissolution of the clusters occurs from the edges rather than layer by layer.
Resumo:
The properties of palladium clusters, generated with the electrochemical scanning tunneling microscope, have been investigated both by experiments and by computer simulations. The clusters are found to be larger and more stable if the tip is moved further towards the electrode surface in the generation process. The simulations suggest that the larger clusters consist of a palladium - gold mixture, which is more stable than pure palladium. Dissolution of the clusters occurs from the edges rather than layer by layer
Resumo:
Background: Non-small cell lung cancer (NSCLC) is the leading cause of cancer mortality worldwide. At present no reliable biomarkers are available to guide the management of this condition. Microarray technology may allow appropriate biomarkers to be identified but present platforms are lacking disease focus and are thus likely to miss potentially vital information contained in patient tissue samples.
Resumo:
This study describes an optimized protocol for the generation of Amplified Fragment Length Polymorphism (AFLP) markers in a stingless bee. Essential modifications to standard protocols are a restriction enzyme digestion (EcoRI and Tru1I) in a two-step procedure, combined with a touchdown program in the selective PCR amplification step and product labelling by incorporation of alpha[P-33]dATP. In an analysis of 75 workers collected from three colonies of Melipona quadrifasciata we obtained 719 markers. Analysis of genetic variability revealed that on average 32% of the markers were polymorphic within a colony. Compared to the overall percentage of polymorphism (44% of the markers detected in our bee samples), the observed rates of within-colony polymorphism are remarkably high, considering that the workers of each colony were all of spring of a singly mated queen.