Additivity of Circular Width

We show that circular width is preserved under connected sum of knots for some cases.Comment: 17 pages, 6 figure

Ontology Access in Grid Environments with WS-DAIOnt and the RDF(S) Realization

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ForoCaos: desarrollo de un foro jerárquico

El proyecto a desarrollar es un foro jerárquico, cuyo funcionamiento se asemeja mucho al de cualquier foro de discusión de los que ya existe en la red. Los foros de discusión son uno de los sistemas más simples de Internet para la difusión del conocimiento en los que puede intervenir cualquier usuario de esta red (normalmente tras haberse dado de alta en el servicio ofertado). En ellos, los participantes plantean cuestiones que los otros usuarios resolverán o intentarán ayudar a resolver. Desafortunadamente, a veces no existen incentivos apropiados para alentar la participación de los usuarios. Este será el punto en el que se centre este proyecto y se propondrá un mecanismo orientado a mercado para promover la actividad de intercambio de conocimiento en estos foros de discusión. La solución propuesta surge de un acercamiento orientado a mercado desde el que manejamos un recurso escaso, el esfuerzo de crear información, que tiene importantes peculiaridades que deben ser tenidas en cuenta. Adicionalmente a la estructura básica, también se ha desarrollado un método para mejorar dinámicamente los resultados del sistema. Este método usa estadísticas sobre el comportamiento de los usuarios, para así minimizar el tiempo de respuesta en el que las preguntas son contestadas satisfactoriamente. [ABSTRACT] The project consists on a hieratical forum whose behaviour is quite similar to any forum available on the net. Discussion forums are one of the simplest Internet-based systems to promote the spread of knowledge in which any of the users of this network can add their own opinions (usually, after having log on in the service). The participating users can set up questions in order to get an answer or some help to solve their problems. Unfortunately, they sometimes lack appropiate incentives to encourage users participation. In this paper we discuss a simple market-oriented mechanism to promote the knowledge exchange activity in discussion forums. The proposed solution departs from other market-oriented approaches since the scarce resource we deal with, the effort to create information, has important peculiarities which must be taken into account. In addition to the basic framework, we have also developed a method to dynamically improve the performance of the system. This method uses statistics about users behavior in order to minimize the response time in which questions are satisfactorily answered

The dust environment of comet 67P/Churyumov–Gerasimenko: results from Monte Carlo dust tail modelling applied to a large ground-based observation data set

We present an extensive data set of ground-based observations and models of the dust environment of comet 67P/Churyumov–Gerasimenko covering a large portion of the orbital arc from about 4.5 au pre-perihelion through 3.0 au post-perihelion, acquired during the current orbit. In addition, we have also applied the model to a dust trail image acquired during this orbit, as well as to dust trail observations obtained during previous orbits, in both the visible and the infrared. The results of the Monte Carlo modelling of the dust tail and trail data are generally consistent with the in situ results reported so far by the Rosetta instruments Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) and Grain Impact Analyser and Dust Accumulator (GIADA). We found the comet nucleus already active at 4.5 au pre-perihelion, with a dust production rate increasing up to ∼3000 kg s−1 some 20 d after perihelion passage. The dust size distribution at sizes smaller than r = 1 mm is linked to the nucleus seasons, being described by a power law of index −3.0 during the comet nucleus southern hemisphere winter but becoming considerably steeper, with values between −3.6 and −4.3, during the nucleus southern hemisphere summer, which includes perihelion passage (from about 1.7 au inbound to 2.4 au outbound). This agrees with the increase of the steepness of the dust size distribution found from GIADA measurements at perihelion showing a power index of −3.7. The size distribution at sizes larger than 1 mm for the current orbit is set to a power law of index −3.6, which is near the average value of in situ measurements by OSIRIS on large particles. However, in order to fit the trail data acquired during past orbits previous to the 2009 perihelion passage, a steeper power-law index of −4.1 has been set at those dates, in agreement with previous trail modelling. The particle sizes are set at a minimum of r = 10 μm, and a maximum size, which increases with decreasing heliocentric distance, in the 1–40 cm radius domain. The particle terminal velocities are found to be consistent with the in situ measurements as derived from the instrument GIADA on board Rosetta

Ontology Access in Grids with WS-DAIOnt and the RDF(S) Realization

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