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A wild-type strain of Staphylococcus aureus, which inactivates a wide variety of aminoglycosides (except the gentamicin components), has been found to harbor a plasmid (RAp01) that mediates the biosynthesis of a nucleotidyltransferase. This enzyme modifies the 4'-hydroxy function of these antibiotics. The plasmid has been studied, the enzyme responsible for this resistance pattern has been isolated by affinity chromatography, and its kinetics and physicochemistry have been characterized. The target of this enzyme has also been located by demonstrating the structure of one inactivated compound, 4'-(O)-adenylyltobramycin. 相似文献
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Transformation-induced alterations in adhesion. Binding of pre-formed cell aggregates to cell layers 总被引:1,自引:0,他引:1
Male and female college students were shown videotapes of supposed male offenders describing the details of thefts they had committed. Videotaped sequences were varied so that offenders were 9 to 10 years old or of college age. Also, actors varied in their mode of emotional self-presentation. Comparisons of punishments suggested by subjects indicated that joyful actors received the highest level of punishment while distressed offenders received the lowest level of suggested punishment. It was also found that the emotions of children exerted a greater persuasive effect on subjects' ratings than did the emotions of adults although the pattern of results was similar across ages. These results were discussed as demonstrating that the age and emotion of an offender can exert considerable influence on the attribution of blame made by a disciplinarian. 相似文献
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Karlov VI Padilla CE Soosaar K Matson LE Chun HM Webb GV 《Journal of the Optical Society of America. A, Optics, image science, and vision》2001,18(10):2565-2576
We present a new approach to processing of interferometric data, which dramatically improves operation on the smallest fraction of the fringe (approximately 1/1,000 of a wavelength and beyond). In particular, this approach, dubbed the variation-invariant subspace tracking approach (VISTA), makes it possible to operate a Michelson interferometer in a highly stable mode in which the estimation of optical path delay becomes invariant (insensitive) to a large class of systematic model errors. This previously unknown invariance property of interferometry follows from the fundamental odd-even symmetry of the channeled spectrum and its derivatives. VISTA offers a powerful algorithmic alternative for alleviating technological challenges in the design of high-precision long-baseline spaceborne interferometers. 相似文献