Simple and Efficient Minimal RDFS

The original RDFS language design includes several features that hinder the task of developers and theoreticians. This paper has two main contributions in the direction of simplifying the language. First, it introduces a small fragment which, preserving the normative semantics and the core functionalities, avoids the complexities of the original specification, and captures the main semantic functionalities of RDFS. Second, it introduces a minimalist deduction system over this fragment, which by avoiding certain rare cases, obtains a simple deductive system and a computationally efficient entailment checking.     

Complexity of the bisection method

The bisection method   is the consecutive bisection of a triangle by the median of the longest side. In this paper we prove a subexponential asymptotic upper bound for the number of similarity classes of triangles generated on a mesh obtained by iterative bisection, which previously was known only to be finite. The relevant parameter is γ/σ$\gamma /\sigma$, where γ$\gamma$ is the biggest and σ$\sigma$ is the smallest angle of the triangle. We get this result by introducing a taxonomy of triangles that precisely captures the behaviour of the bisection method. We also prove that the number of directions on the plane given by the sides of the triangles generated is finite. Additionally, we give purely geometrical and intuitive proofs of classical results for the bisection method.     

A Survey on Procedural Modelling for Virtual Worlds

Procedural modelling deals with (semi‐)automatic content generation by means of a program or procedure. Among other advantages, its data compression and the potential to generate a large variety of detailed content with reduced human intervention, have made procedural modelling attractive for creating virtual environments increasingly used in movies, games and simulations. We survey procedural methods that are useful to generate features of virtual worlds, including terrains, vegetation, rivers, roads, buildings and entire cities. In this survey, we focus particularly on the degree of intuitive control and of interactivity offered by each procedural method, because these properties are instrumental for their typical users: designers and artists. We identify the most promising research results that have been recently achieved, but we also realize that there is far from widespread acceptance of procedural methods among non‐technical, creative professionals. We conclude by discussing some of the most important challenges of procedural modelling.     

LS-VisionDraughts: improving the performance of an agent for checkers by integrating computational intelligence,reinforcement learning and a powerful search method

This paper presents LS-VisionDraughts: an efficient unsupervised evolutionary learning system for Checkers whose contribution is to automate the process of selecting an appropriate representation for the board states – by means of Evolutionary Computation – keeping a deep look-ahead (search depth) at the moment of choosing an adequate move. It corresponds to a player Multi Layer Perceptron Neural Network whose weights are updated through an evaluation function that is automatically adjusted by means of the Temporal Difference methods. A Genetic Algorithm automatically chooses a concise and efficient set of functions, which describe various scenarios associated with Checkers – called features – to represent the board states in the input layer of the Neural Network. It means that each individual of the Genetic Algorithm is a candidate set of features that is associated to a distinct Multi Layer Perceptron Neural Network. The output layer of the Neural Network is a real number (prediction) that indicates to which extent the input state is favorable to provide a better agent performance. In LS-VisionDraughts, a particular version of the search algorithm Alpha-Beta, called fail-soft Alpha-Beta, combined with Table Transposition, Iterative Deepening and ordered tree, uses this prediction value to choose the best move corresponding to the current board state. The best individual is chosen by means of numerous tournaments involving these selfsame Neural Networks. The architecture of LS-VisionDraught is inspired on the agent NeuroDraughts. However, the former system enhances the performance of the latter by automating the selection of the features through Evolutionary Computation and by replacing its Minimax search algorithm with the improved search strategy resumed above. This procedure allows for a 95 % reduction in the search runtime. Further, it remarkably increases the search tree depth. The results obtained from evaluative tournaments confirm the advances of LS-VisionDraughts compared to its opponents. It is however important to point out that LS-VisionDraughts learns practically without human supervision, contrary to the current automatic world champion Chinook, which has been built in a strongly supervised manner.     

Strategies for urban drought risk management: a comparison of 10 large cities

Sustainable development of cities requires robust water supply systems, yet many cities need to resort to ad hoc measures when faced with a drought. This article aims to explore how cities can do better in reducing the risk of water shortage due to drought. To that end, a classification of drought measures in urban water supply systems is proposed, and then applied to 10 cities that recently faced a drought. We find that these cities used a relatively limited number and variety of measures. The classification can help cities evaluate different types of measures for reducing long-term water stress and limit the impact of extreme droughts.     

The fate of radiolabeled steroids in ovaries and eggs of the tobacco hornworm,Manduca sexta

To determine the precursors and the fate of 26-hydroxyecdysone in eggs, the fate of labeled putative ecdysteroid precursors was examined in the tobacco hornworm,Manduca sexta. Following injection of [¹⁴C]cholesterol, 22,25[¹⁴C]dideoxyecdysome or [³H]ecdysone into female pupae (day 16), only [¹⁴C]cholesterol was incorporated and metabolized. It was converted to labeled nonecdysteroid and ecdysteroid conjugates, of which the latter in ovaries and 48- to 64-hr-old eggs is mainly 26-hydroxyecdysone 26-phosphate (>85% in ovaries). Quantitation of the ecdysteroid conjugate by reversed-phase high performance liquid chromatography (RP-HPLC) showed that the levels of 26-hydroxyecdysone 26-phosphate were 31 μg/g of ovaries from 4-day-old females and 25 μg/g and 17 μg/g of 48- to 64-hr-old and 72- to 88-hr-old eggs, respectively. The RP-HPLC of the conjugate fraction of 48- to 64-hr-old eggs showed an additional peak of radioactive material eluting about three min before the 26-hydroxyecdysone 26-phosphate. The quantity of this material increased in the 72-to 88-hr-old eggs, though it was not detected in the analyses of the conjugate fraction from ovaries. Additional peaks of radioactive material eluting before the 26-hydroxyecdysone 26-phosphate peak were observed in the chromatogram of the conjugates of 72- to 88-hr-old eggs. These radioactive materials need to be identified to determine the ultimate fate of ecdysteroids in the developing embryos of the tobacco hornworm. No radioactive free ecdysteroids were detected in either egg age group.     

The effect of HCl and NaOH treatment on structural transformations in a ball-milled anthracite after thermal and chemical processing

Nanocrystalline diamond (NCD) was observed after reactive ball milling of anthracite coal with cyclohexene, a high-temperature (1400 °C) thermal anneal, and a 4 M HCl treatment followed by a 10 M NaOH treatment. A crystalline carbon region was also observed when the thermal anneal was omitted. This crystalline region is highly unstable and converts to NCD and carbon onions via electron irradiation in the TEM. X-ray diffraction, Raman, ash content, and temperature-programmed oxidation (TPO) data suggest that tetrahedral amorphous carbon is formed during milling, iron carbides are formed during the thermal anneal step, and both the HCl and NaOH purification steps lead to changes in carbon structure. NaOH oxidizes metal carbides and this process may contribute to NCD formation.     

A framework for adaptive execution in grids

Grids offer a dramatic increase in the number of available processing and storing resources that can be delivered to applications. However, efficient job submission and management continue being far from accessible to ordinary scientists and engineers due to their dynamic and complex nature. This paper describes a new Globus based framework that allows an easier and more efficient execution of jobs in a ‘submit and forget’ fashion. The framework automatically performs the steps involved in job submission and also watches over its efficient execution. In order to obtain a reasonable degree of performance, job execution is adapted to dynamic resource conditions and application demands. Adaptation is achieved by supporting automatic application migration following performance degradation, ‘better’ resource discovery, requirement change, owner decision or remote resource failure. The framework is currently functional on any Grid testbed based on Globus because it does not require new system software to be installed in the resources. The paper also includes practical experiences of the behavior of our framework on the TRGP and UCM‐CAB testbeds. Copyright © 2004 John Wiley & Sons, Ltd.     

Synthesis and sol-gel polymerization of [Si8O12](OCH3)8

Sol-gel polymerization of [Si₈O₁₂](OCH₃)₈ in an inert solvent under neutral conditions has been shown to yield very high-surface area silica xerogels [P. C. Cagleet al., Mater. Res. Soc. Symp. Proc. 180, 29 (1990)]. Two recent results relevant to this process are described here. First, a practical synthetic route to [Si₈O₁₂](OCH₃)₈ is described that allows multigram quantities to be conveniently prepared. Second, TEM studies are reported that confirm retention of the [Si₈O₁₂] cubic core structure in high-surface area, [Si₈O₁₂](OCH₃)₈ ^? derived xerogels.