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A better understanding of pruning methods based on a ranking of weights according to their saliency in a trained network requires further information on the statistical properties of such saliencies. We focus on two-layer networks with either a linear or nonlinear output unit, and obtain analytic expressions for the distribution of saliencies and their logarithms. Our results reveal unexpected universal properties of the log-saliency distribution and suggest a novel algorithm for saliency-based weight ranking that avoids the numerical cost of second derivative evaluations.  相似文献   
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The survival of some elms to Dutch elm disease (DED) epidemics could be related with the application of disinfectant products based on simple phenols. To test this hypothesis, the protective effect of different phenolic treatments in Ulmus minor trees was evaluated through inoculations with Ophiostoma novo-ulmi, the current DED pathogen. During spring 2004 and spring 2005, 4-year-old elms were: (i) watered with a 0.02% solution of the phenolic fraction of phenolic oil, (ii) watered with a 0.02 and 0.2% solution of a phenol–cresol mixture, and (iii) trunk injected with a 0.2% solution of phenol–cresol mixture. In May, trees were artificially inoculated with O. novo-ulmi. At the end of the 2004 and 2005 vegetative periods, phenol-treated trees showed significantly lower wilting values than control trees. One week of bud break delay was observed in trees watered with the 0.2% solution of phenol–cresol mixture. Fourier transform-infrared spectroscopy and electrospray ionisation mass spectrometry evidenced enhanced levels of suberin-like compounds in phenol-treated trees with respect to non-treated trees. The deposition of suberin in xylem tissues, as a response to phenol treatments, might be considered as one of the mechanisms of resistance of elms to O. novo-ulmi.  相似文献   
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