Reasoning about context in uncertain pervasive computing environments

Context-awareness is a key to enabling intelligent adaptation in pervasive computing applications that need to cope with dynamic and uncertain environments. Addressing uncertainty is one of the major issues in context-based situation modeling and reasoning approaches. Uncertainty can be caused by inaccuracy, ambiguity or incompleteness of sensed context. However, there is another aspect of uncertainty that is associated with human concepts and real-world situations. In this paper we propose and validate a Fuzzy Situation Inference (FSI) technique that is able to represent uncertain situations and reflect delta changes of context in the situation inference results. The FSI model integrates fuzzy logic principles into the Context Spaces (CS) model, a formal and general context reasoning and modeling technique for pervasive computing environments. The strengths of fuzzy logic for modeling and reasoning of imperfect context and vague situations are combined with the CS model's underlying theoretical basis for supporting context-aware pervasive computing scenarios. An implementation and evaluation of the FSI model are presented to highlight the benefits of the FSI technique for context reasoning under uncertainty</p

An artificial immune system for fuzzy-rule induction in data mining

This work proposes a classification-rule discovery algorithm integrating artificial immune systems and fuzzy systems. The algorithm consists of two parts: a sequential covering procedure and a rule evolution procedure. Each antibody (candidate solution) corresponds to a classification rule. The classification of new examples (antigens) considers not only the fitness of a fuzzy rule based on the entire training set, but also the affinity between the rule and the new example. This affinity must be greater than a threshold in order for the fuzzy rule to be activated, and it is proposed an adaptive procedure for computing this threshold for each rule. This paper reports results for the proposed algorithm in several data sets. Results are analyzed with respect to both predictive accuracy and rule set simplicity, and are compared with C4.5rules, a very popular data mining algorithm

Consistent Truncation to Three Dimensional (Super-)gravity

For a general three dimensional theory of (super-)gravity coupled to arbitrary matter fields with arbitrary set of higher derivative terms in the effective action, we give an algorithm for consistently truncating the theory to a theory of pure (super-)gravity with the gravitational sector containing only Einstein-Hilbert, cosmological constant and Chern-Simons terms. We also outline the procedure for finding the parameters of the truncated theory. As an example we consider dimensional reduction on S^2 of the 5-dimensional minimal supergravity with curvature squared terms and obtain the truncated theory without any curvature squared terms. This truncated theory reproduces correctly the exact central charge of the boundary CFT.Comment: LaTeX file, 22 page

Evidence of a massive planet candidate orbiting the young active K5V star BD+20 1790

Original article can be found at: http://www.aanda.org/ Copyright The European Southern Observatory (ESO). DOI: 10.1051/0004-6361/200811000Context. BD+20 1790 is a young active, metal-rich, late-type K5Ve star. We have undertaken a study of stellar activity and kinematics for this star over the past few years. Previous results show a high level of stellar activity, with the presence of prominence-like structures, spots on the surface, and strong flare events, despite the moderate rotational velocity of the star. In addition, radial velocity variations with a semi-amplitude of up to 1 km s-1 were detected. Aims. We investigate the nature of these radial velocity variations, in order to determine whether they are due to stellar activity or the reflex motion of the star induced by a companion. Methods. We have analysed high-resolution echelle spectra by measuring stellar activity indicators and computing radial velocity (RV) and bisector velocity spans. Two-band photometry was also obtained to produce the light curve and determine the photometric period. Results. Based upon the analysis of the bisector velocity span, as well as spectroscopic indices of chromospheric indicators, Ca ii H & K, Hα, and taking the photometric analysis into account, we report that the best explanation for the RV variation is the presence of a substellar companion. The Keplerian fit of the RV data yields a solution for a close-in massive planet with an orbital period of 7.78 days. The presence of the close-in massive planet could also be an interpretation for the high level of stellar activity detected. Since the RV data are not part of a planet search programme, we can consider our results as a serendipitous evidence of a planetary companion. To date, this is the youngest main sequence star for which a planetary candidate has been reported.Peer reviewe

Extremal black holes in D=5: SUSY vs. Gauss-Bonnet corrections

We analyse near-horizon solutions and compare the results for the black hole entropy of five-dimensional spherically symmetric extremal black holes when the N=2 SUGRA actions are supplied with two different types of higher-order corrections: (1) supersymmetric completion of gravitational Chern-Simons term, and (2) Gauss-Bonnet term. We show that for large BPS black holes lowest order \alpha' corrections to the entropy are the same, but for non-BPS are generally different. We pay special attention to the class of prepotentials connected with K3\times T^2 and T^6 compactifications. For supersymmetric correction we find beside BPS also a set of non-BPS solutions. In the particular case of T^6 compactification (equivalent to the heterotic string on $T^4\times S^1$) we find the (almost) complete set of solutions (with exception of some non-BPS small black holes), and show that entropy of small black holes is different from statistical entropy obtained by counting of microstates of heterotic string theory. We also find complete set of solutions for K3\times T^2 and T^6 case when correction is given by Gauss-Bonnet term. Contrary to four-dimensional case, obtained entropy is different from the one with supersymmetric correction. We show that in Gauss-Bonnet case entropy of small ``BPS'' black holes agrees with microscopic entropy in the known cases.Comment: 28 pages; minor changes, version to appear in JHE

Conservation of the Spanish Alano dog breed: phaneroptical characterisation

A preliminary phaneroptical characterisation of the Spanish Alano Dog Breed is done studying, on a random sample formed by 135 specimens, six external variables: coat colour and distribution; hair type; mucosae, and iris colour; type of bite; and absence of premolars. We have concluded that this breed is characterised by the presentation of yellow and brindled coats, with other coat colours as residuals, standing out the combined black and brindled coat, not present in other related breeds, what could be considered as a breed marker character. The breed is also characterised by short hair, black pigmented mucosae , brown iris, with general presentation of a mask. The dentition characteristics are the presence of a prognatic bite (slight) and absence of premolars, both characters related to the origin of the breed.Se realiza una caracterización faneróptica preliminar sobre una muestra aleatoria de 135 ejemplares de raza Alano Español. Se consideran las variables: color y distribución de la capa, tipo de pelo, coloración de las mucosas e iris, tipo de mordida y ausencia de premolares. Se concluye que el Alano Español presenta como capas predominantes la barcina y la leonada, siendo minoritarias la capa negro y bardino, ausente en la mayoría de razas consultadas, y que podría constituirse como un carácter marcador de raza. Asimismo la raza se caracteriza por presentar pelo liso, mucosas pigmentadas en negro, iris de color castaño, con presencia de máscara generalmente. La raza mayoritariamente presenta una mordida prognática (tijera invertida), con ausencia de premolares, caracteres ambos acordes con el origen de la raza

On walls of marginal stability in N=2 string theories

We study the properties of walls of marginal stability for BPS decays in a class of N=2 theories. These theories arise in N=2 string compactifications obtained as freely acting orbifolds of N=4 theories, such theories include the STU model and the FHSV model. The cross sections of these walls for a generic decay in the axion-dilaton plane reduce to lines or circles. From the continuity properties of walls of marginal stability we show that central charges of BPS states do not vanish in the interior of the moduli space. Given a charge vector of a BPS state corresponding to a large black hole in these theories, we show that all walls of marginal stability intersect at the same point in the lower half of the axion-dilaton plane. We isolate a class of decays whose walls of marginal stability always lie in a region bounded by walls formed by decays to small black holes. This enables us to isolate a region in moduli space for which no decays occur within this class. We then study entropy enigma decays for such models and show that for generic values of the moduli, that is when moduli are of order one compared to the charges, entropy enigma decays do not occur in these models.Comment: 40 pages, 2 figure

Sub-terahertz, microwaves and high energy emissions during the December 6, 2006 flare, at 18:40 UT

The presence of a solar burst spectral component with flux density increasing with frequency in the sub-terahertz range, spectrally separated from the well-known microwave spectral component, bring new possibilities to explore the flaring physical processes, both observational and theoretical. The solar event of 6 December 2006, starting at about 18:30 UT, exhibited a particularly well-defined double spectral structure, with the sub-THz spectral component detected at 212 and 405 GHz by SST and microwaves (1-18 GHz) observed by the Owens Valley Solar Array (OVSA). Emissions obtained by instruments in satellites are discussed with emphasis to ultra-violet (UV) obtained by the Transition Region And Coronal Explorer (TRACE), soft X-rays from the Geostationary Operational Environmental Satellites (GOES) and X- and gamma-rays from the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The sub-THz impulsive component had its closer temporal counterpart only in the higher energy X- and gamma-rays ranges. The spatial positions of the centers of emission at 212 GHz for the first flux enhancement were clearly displaced by more than one arc-minute from positions at the following phases. The observed sub-THz fluxes and burst source plasma parameters were found difficult to be reconciled to a purely thermal emission component. We discuss possible mechanisms to explain the double spectral components at microwaves and in the THz ranges.Comment: Accepted version for publication in Solar Physic

Kondo lattice model with a direct exchange interaction between localized moments

We study the Kondo lattice model with a direct antiferromagnetic exchange interaction between localized moments. Ferromagnetically long-range ordered state coexisting with the Kondo screening shows a continuous quantum phase transition to the Kondo singlet state. We obtain the value of the critical point where the magnetizations of the localized moments and the conduction electrons vanish. The magnetization curves yield a universal critical exponent independent of the filling factors and the strength of the interaction between localized moments. It is shown that the direct exchange interaction between localized moments introduces another phase transition from an antiferromagnetic ordering to a ferromagnetic ordering for small Kondo exchange interaction. We also explain the local minimum of the Kondo temperature in recent experiments.Comment: 6 pages, 5 figures, final versio

Morphostructural characterisation of Spanish Alano as a base for its conservation: preliminar results

Using 68 pure exemplars of the Spanish Alano Dog Breed (37 males and 31 females) we have developed a preliminary study of the breed characterisation analysing several morphostructural variables as a base for the definition of racial pattern, considering that a one of the main objectives of the project entitled Planning of the recuperation and conservation of the Spanish Alano canine breed. All the studied zoometric variables reflected bigger values if males than in females, but we could not proved statistically a clear sexual dimorphism in most of the studied variables. Our results coincide with descriptions and data published by other authors with respect to this breed. In general, from this study we conclude that this population is characterised by braquicephalic proportions, and sublongilineous body proportions, all inside a strong and compact morphostructure. It permit us to clasify this breed inside the group of light molosoids caught dogs.Sobre un total de 68 ejemplares de la raza Alano Español (37 machos y 31 hembras) se realiza un estudio de caracterización racial preliminar, analizando diversas variables morfoestructurales, como base para su utilización en la redacción del patrón racial, considerado como uno de los objetivos iniciales prioritarios en el proyecto denominado Planificación de la recuperación y conservación de la raza canina Alano Español. Todas las variables zoométricas estudiadas reflejaron valores mayores en machos que en hembras, aunque no comprobamos estadísticamente un dimorfismo sexual manifiesto en la mayoría de dichas variables. Asimismo nuestros resultados concuerdan con las descripciones y datos aportados por los distintos autores que estudiaron esta raza anteriormente. En líneas generales, de este estudio se puede concluir que la población estudiada se caracteriza por presentar características braquicéfalas, y proporciones corporales sublongilíneas dentro de una morfoestructura general fuerte y compacta, lo que nos permite encuadrar esta raza dentro del grupo de perros molosos ligeros de presa