In a 1 ha square plot of terrafirme forest at 260 m elevation in Amazonian Ecuador, all trees with diameter at breast height (dbh) />5 cm were studied. There were 1561 individuals, 473 species, 187 genera and 54 families. Of these, 693 individuals, 307 species, 138 genera and 46 families had a dbh i>10 cm. This is the highest number of tree species ever recorded for a tropical rain forest sample of this size. In both dbh classes, the most species-rich families were: Fabaceae sensu lato (including Mimosaceae and Caesalpiniaceae), Lauraceae and Sapotaceae; the most species-rich genera, were Pouteria, Inga and Protium. The vertical space was partitioned among species: 166 species were found only in the 5-10 dbh cm class and were mostly sub-canopy treelets, and 307 species with dbh t>10 cm were mostly large canopy trees.

Abstract-We present an active exploration strategy that complements Pose SLAM [1] and optimal navigation in Pose SLAM [2]. The method evaluates the utility of exploratory and place revisiting sequences and chooses the one that minimizes overall map and path entropies. The technique considers trajectories of similar path length taking marginal pose uncertainties into account. An advantage of the proposed strategy with respect to competing approaches is that to evaluate information gain over the map, only a very coarse prior map estimate needs to be computed. Its coarseness is independent and does not jeopardize the Pose SLAM estimate. Moreover, a replanning scheme is devised to detect significant localization improvement during path execution. The approach is tested in simulations in a common publicly available dataset comparing favorably against frontier based exploration.

Abstract-We present an approach to the problem of 3D map building in urban settings for service robots, using threedimensional laser range scans as the main data input. Our system is based on the probabilistic alignment of 3D point clouds employing a delayed-state information-form SLAM algorithm, for which we can add observations of relative robot displacements efficiently. These observations come from the alignment of dense range data point clouds computed with a variant of the iterative closest point algorithm. The datasets were acquired with our custom built 3D range scanner integrated into a mobile robot platform. Our mapping results are compared to a GISbased CAD model of the experimental site. The results show that our approach to 3D mapping performs with sufficient accuracy to derive traversability maps that allow our service robots navigate and accomplish their assigned tasks on a urban pedestrian area.

Abstract-An information-driven autonomous robotic exploration method on a continuous representation of unknown environments is proposed in this paper. The approach conveniently handles sparse sensor measurements to build a continuous model of the environment that exploits structural dependencies without the need to resort to a fixed resolution grid map. A gradient field of occupancy probability distribution is regressed from sensor data as a Gaussian process providing frontier boundaries for further exploration. The resulting continuous global frontier surface completely describes unexplored regions and, inherently, provides an automatic stop criterion for a desired sensitivity. The performance of the proposed approach is evaluated through simulation results in the well-known Freiburg and Cave maps.

No abstract

Abstract-The probabilistic belief networks that result from standard feature-based simultaneous localization and map building cannot be directly used to plan trajectories. The reason is that they produce a sparse graph of landmark estimates and their probabilistic relations, which is of little value to find collision free paths for navigation. In contrast, we argue in this paper that Pose SLAM graphs can be directly used as belief roadmaps. We present a method that devises optimal navigation strategies by searching for the path in the pose graph with lowest accumulated robot pose uncertainty, independently of the map reference frame. The method shows improved navigation results when compared to shortest paths both over synthetic data and real datasets.

Abstract-The probabilistic belief networks that result from standard feature-based simultaneous localization and map building cannot be directly used to plan trajectories. The reason is that they produce a sparse graph of landmark estimates and their probabilistic relations, which is of little value to find collision free paths for navigation. In contrast, we argue in this paper that Pose SLAM graphs can be directly used as belief roadmaps. We present a method that devises optimal navigation strategies by searching for the path in the pose graph with lowest accumulated robot pose uncertainty, independently of the map reference frame. The method shows improved navigation results when compared to shortest paths both over synthetic data and real datasets.

ResumenEste artículo analiza cuáles han sido los principales obstáculos para el crecimiento económico de México durante los últimos veinticinco años, con particular énfasis en el periodo posterior a la entrada en vigor del Tratado de Libre Comercio de América del Norte (tlcan). Si bien la polí-tica económica mexicana desde 1982 se ha guiado por una serie de suposiciones y disposiciones conocidas como el Consenso de Washington, estas políticas en lugar de estimular un mayor dinamismo de la economía mexicana han acentuado sus problemas estructurales y reducido el potencial de crecimiento del país. También se analiza cómo las políticas fiscal, monetaria, cambiaria y de libre comercio han obstaculizado el crecimiento económico. AbstractThis article analyzes the main obstacles to economic growth in Mexico during the past twenty five years, with a focus on the period after the passage of the North American Free Trade Agreement (nafta). Although Mexican economic policy since 1982 has been guided by a set of assumptions and prescription known as the Washington Consensus, these economic policies rather than spurring faster economic growth have accentuated the structural problems of the Mexican economy and have reduced Mexico's growth potential. The article also analyzes how fiscal, monetary, exchange rate and free trade policies have hampered economic growth.Palabras claves: liberalización comercial y financiera, cambio del patrón de especialización, bajo crecimiento económico.