On the emergent Semantic Web and overlooked issues

The emergent Semantic Web, despite being in its infancy, has already received a lotof attention from academia and industry. This resulted in an abundance of prototype systems and discussion most of which are centred around the underlying infrastructure. However, when we critically review the work done to date we realise that there is little discussion with respect to the vision of the Semantic Web. In particular, there is an observed dearth of discussion on how to deliver knowledge sharing in an environment such as the Semantic Web in effective and efficient manners. There are a lot of overlooked issues, associated with agents and trust to hidden assumptions made with respect to knowledge representation and robust reasoning in a distributed environment. These issues could potentially hinder further development if not considered at the early stages of designing Semantic Web systems. In this perspectives paper, we aim to help engineers and practitioners of the Semantic Web by raising awareness of these issues

Dinâmica e distribuição das áreas alteradas por ação antrópica no Cerrado matogrossense no período de 2002 a 2008.

The Cerrado biome has approximately two million square kilometers, which represents 23% of the country extension. With a large territory, it is considered one of the hotspots of the Planet, ie, a priority area for conservation. However, with favorable soil and climate characteristics, this biome has become the subject of great affluence for agricultural purposes since the 1970s. With government incentives, conditions for the expansion of agriculture were created. All these factors were decisive to the expansion of so-called "agricultural frontier?, which provided important positive impacts on the Brazilian economy. However, concomitantly, increasing environmental changes are observed in this biome. The anthropogenic occupation has as the first action the deforestation and the reduction of native vegetation, and much of this occupation is linked to agricultural activity. Among several States which compose this biome, Mato Grosso has a prominent place in national agricultural production, primarily due to soybean and corn plantations. Thus, this study aims to determine the dynamics and the spatial distribution changes due to anthropogenic activities in the Cerrado of Mato Grosso state in the 2002 to 2008 time period. The deforested data from the analyzed period were obtained from ?Projeto de Monitoramento do Desmatamento dos Biomas Brasileiros por Satélite? (PMDBBS). These information were intersected with mesoregions, soil, vegetation and geomorphological maps of the study area. The results showed that highest conversions occurred in North mesoregion. The predominant vegetation type deforested was the wooded savanna and according to the soil and geomorphological maps, the results demonstrated a preference for deep soils and plan relief

Interaction Between Superconducting and Ferromagnetic Order Parameters in Graphite-Sulfur Composites

The superconductivity of graphite-sulfur composites is highly anisotropic and associated with the graphite planes. The superconducting state coexists with the ferromagnetism of pure graphite, and a continuous crossover from superconducting to ferromagnetic-like behavior could be achieved by increasing the magnetic field or the temperature. The angular dependence of the magnetic moment m(alpha) provides evidence for an interaction between the ferromagnetic and the superconducting order parameters.Comment: 11 pages, 4 figures, to be published in Phys. Rev.

On the geometric quantization of twisted Poisson manifolds

We study the geometric quantization process for twisted Poisson manifolds. First, we introduce the notion of Lichnerowicz-twisted Poisson cohomology for twisted Poisson manifolds and we use it in order to characterize their prequantization bundles and to establish their prequantization condition. Next, we introduce a polarization and we discuss the quantization problem. In each step, several examples are presented

Atividade microbiana na rizosfera de goiabeiras micorrizadas e cultivadas em solo infestado com Meloidogyne mayaguensis Rammah & Hirschmann.

A utilização de FMA (fungos micorrízicos arbusculares) favorece o crescimento vegetal e diminui os danos causados por fitopatógenos (MAlA et aI. 2006), intluenciando a microbiota do solo

Gradient-dependent density functionals of the PBE type for atoms, molecules and solids

One of the standard generalized-gradient approximations (GGAs) in use in modern electronic-structure theory, PBE, and a recently proposed modification designed specifically for solids, PBEsol, are identified as particular members of a family of functionals taking their parameters from different properties of homogeneous or inhomogeneous electron liquids. Three further members of this family are constructed and tested, together with the original PBE and PBEsol, for atoms, molecules and solids. We find that PBE, in spite of its popularity in solid-state physics and quantum chemistry, is not always the best performing member of the family, and that PBEsol, in spite of having been constructed specifically for solids, is not the best for solids. The performance of GGAs for finite systems is found to sensitively depend on the choice of constraints steaming from infinite systems. Guidelines both for users and for developers of density functionals emerge from this work.Comment: 4 pages, PRB Rapid Comm. accepte