We give a survey up to 1989 on the Steiner tree problems which include the four important cases of euclidean, rectilinear, graphic, phylogenetic and some of their generalizations. We also provide a rather comprehensive and up-to-date bibliography which covers more than three hundred items.

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Floorplan design is an important stage in the VLSI design cycle. Designing a floorplan calls for arranging a given set of modules in the plane to minimize the weighted sum of area and wirelength measures. This paper presents a method to solve the floorplan design problem using distributed genetic algorithms. Distributed genetic algorithms, based on the paleontological theory of punctuated equilibria, offer a conceptual modification to the traditional genetic algorithms. Experimental results on several problem instances demonstrate the efficacy of our method, and point out the advantages o f using this method over other methods, such as simulated annealing. Our method has performed better than the simulated annealing approach, both in terms of the average cost of the solutions found and the best-found solution, in almost all the problem instances tried.

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Hurricanes are an important part of the natural disturbance regime of the Yucatán Peninsula with the potential to alter forest structure and composition, yet investigations of species-level responses to severe winds are limited in this region. The effect of a category 5 hurricane (Hurricane Dean, 21 August 2007) on dry tropical forests across the southern Yucatán was examined with respect to tree damage, mortality, and sprouting. Damage was assessed 9-11 mo following the hurricane in 92 (500 m 2 ) plots stratified by wind speed and normalized difference vegetation index (NDVI) change classes over a 25,000 km 2 study area. We investigated the relative importance of biotic (i.e., species, size, and wood density) and abiotic (i.e., wind speed) factors to better explain patterns of damage. Overall mortality was low (3.9%), however, mortality of less common species (8.5%) was elevated more than fourfold above that of 28 common species (1.8%), indicating immediate selective consequences for community composition. Species varied in the degree and type of damage experienced, with susceptibility increasing with tree diameter and height. Wood density influenced damage patterns only in areas where a critical threshold in storm intensity was exceeded (wind speeds Z210 km/h). Although overall, damage severity increased with wind speed, common coastal species were more resistant to damage than species distributed farther inland. Our findings suggest that selective pressure exerted by frequent hurricane disturbance has, and will, continue to impact the floristic composition of forests on the Yucatán Peninsula, favoring certain wind-resistant species.Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp.