2,437 research outputs found

    Geonic black holes and remnants in Eddington-inspired Born-Infeld gravity

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    We show that electrically charged solutions within the Eddington-inspired Born-Infeld theory of gravity replace the central singularity by a wormhole supported by the electric field. As a result, the total energy associated with the electric field is finite and similar to that found in the Born-Infeld electromagnetic theory. When a certain charge-to-mass ratio is satisfied, in the lowest part of the mass and charge spectrum the event horizon disappears yielding stable remnants. We argue that quantum effects in the matter sector can lower the mass of these remnants from the Planck scale down to the TeV scale.Comment: 7 double column pages, 1 figur

    Beyond Rainbow-Ladder in a covariant three-body Bethe-Salpeter approach: Baryons

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    We report on recent results of a calculation of the nucleon and delta masses in a covariant bound-state approach, where to the simple rainbow-ladder gluon-exchange interaction kernel we add a pion-exchange contribution to account for pion cloud effects. We observe good agreement with lattice data at large pion masses. At the physical point our masses are too large by about five percent, signaling the need for more structure in the gluon part of the interaction.Comment: 4 pages, 3 figures, Proceedings of The 13th International Conference on Meson-Nucleon Physics and the Structure of the Nucleon (MENU 2013), Rom

    Recurrent points of continuous functions on connected linearly ordered spaces

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    Let L be a connected linearly ordered topological space and let f be a continuous function from L into itself. if P (f) and R(f) denote the set of periodic points and the set of recurrent points of f respectively, we show that the center of f is clLP(f)cl_{L}P(f) and the depth of the center is at most 2. Furthermore we have clLP(f)=clLR(f)cl_{L}P(f)=cl_{L}R(f)

    Cyanobacteria in Spanish reservoirs. How frequently are they toxic?

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    Cyanobacteria in Spanish reservoirs. How frequently are they toxic?

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    In this paper we analyse the cyanobacterial occurrence in the Spanish reservoirs, using data obtained from published material or reports of several Spanish institutions. Our analysis shows that potentially toxic cyanobacteria are widespread in the Spanish reservoirs, dominating the phytoplankton community at least once during the study period in a high proportion of the investigated reservoirs (35-48%). The bibliographic data also show that in Europe and in the rest of the World more than 70% of the samples analysed from potentially toxic cyanobacteria were toxic. Extrapolating these data we can assume that a high proportion of the Spanish reservoirs (between 25 and 35 %) present a high probability of developing blooms of toxic cyanobacteria. Finally, the available data about the presence of cyanotoxins in different Spanish Basins show that cyanotoxins are present in all the analysed basins and occasionally show very high toxin concentrations.En este artículo analizamos la presencia de cianobacterias en los embalses españoles, fundamentalmente basándonos en datos presentes en la literatura científica y en informes de distintos organismos. Nuestro análisis demuestra que en un alto porcentaje de los embalses estudiados (entre el 35 y el 48%) las cianobacterias potencialmente tóxicas dominaron la comunidad del fitoplancton en al menos una ocasión durante el periodo de estudio. Los datos bibliográficos también demuestran que en Europa y en el resto del mundo aparecieron cianotoxinas en más del 70% de las muestras analizadas de afloramientos de cianobacterias potencialmente tóxicas. Extrapolando estos datos podemos deducir que al menos entre un 25 y un 35% de los embalses españoles muestran una elevada probabilidad a desarrollar afloramientos tóxicos. Finalmente se analizan los datos disponibles sobre cianotoxinas en España, mostrando que en diversas cuencas hidrográficas las cianotoxinas están presentes y ocasionalmente en altas concentraciones

    Using Kepler transit observations to measure stellar spot belt migration rates

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    Planetary transits provide a unique opportunity to investigate the surface distributions of star spots. Our aim is to determine if, with continuous observation (such as the data that will be provided by the Kepler mission), we can in addition measure the rate of drift of the spot belts. We begin by simulating magnetic cycles suitable for the Sun and more active stars, incorporating both flux emergence and surface transport. This provides the radial magnetic field distribution on the stellar surface as a function of time. We then model the transit of a planet whose orbital axis is misaligned with the stellar rotation axis. Such a planet could occult spots at a range of latitudes. This allows us to complete the forward modelling of the shape of the transit lightcurve. We then attempt the inverse problem of recovering spot locations from the transit alone. From this we determine if transit lightcurves can be used to measure spot belt locations as a function of time. We find that for low-activity stars such as the Sun, the 3.5 year Kepler window is insufficient to determine this drift rate. For more active stars, it may be difficult to distinguish subtle differences in the nature of flux emergence, such as the degree of overlap of the "butterfly wings". The rate and direction of drift of the spot belts can however be determined for these stars. This would provide a critical test of dynamo theory.Comment: 5 pages. Accepted for publication in Monthly Notices of the Royal Astronomical Society Letter

    The influence of age and gender in the interaction with touch screens

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    Touch screens are nowadays one of the major interfaces in the interaction between humans and technology, mostly due to the significant growth in the use of smartphones and tablets in the last years. This broad use, that reaches people from all strata of society, makes touch screens a relevant tool to study the mechanisms that influence the way we interact with electronic devices. In this paper we collect data regarding the interaction patterns of different users with mobile devices. We present a way to formalize these interaction patterns and analyze how aspects such as age and gender influence them. The results of this research may be relevant for developing mobile applications that identify and adapt to the users or their characteristics, including impairments in fine motor skills or in cognitive function.Fundos Europeus Estruturais e de Investimento (FEEI) through Programa Operacional Regional Norte, in the scope of project NORTE01-0145-FEDER-02357

    Can People with Chronic Neck Pain Recognize Their Own Digital Pain Drawing?

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    Background: Although the reliability of pain drawings (PDs) has been confirmed in people with chronic pain, there is a lack of evidence about the validity of the PD, that is, does the PD accurately represent the pain experience of the patient? Objectives: We investigate whether people with chronic neck pain (CNP) can recognize their own PD to support the validity of the PD in reporting the experience of pain. Moreover, we examined the association between their ability to recognize their own PD with their levels of pain intensity and disability and extent of psychosocial and somatic features. Study Design: Experimental. Setting: University Laboratory. Methods: Individuals with CNP completed their PD on a digital body chart, which was then automatically modified with specific dimensions using a novel software, providing an objective range of distortion and eliminating errors, which could potentially occur in manually controlled visual-subjective based methods. Following a 10-minute break listening to music, a series of 20 PDs were presented to each patient in a random order, with only 2 being their original PD. For each PD, the patients rated its likeliness to their own original PD on a scale from 0 to 100, with 100 representing “this is my pain.” Results: Overall, the patients rated their original PD with a median score of 92% similarity, followed by 91.8% and 89.5% similarity when presented with a PD scaled down to 75% and scaled up by 150% of the original size, respectively; these scores were not significantly different to the ratings given for their original PD. The PD with horizontal translation by 40 pixels (8%) and vertical translation by 70 pixels (12.8%) were rated as the most dissimilar to their original PD; these scores were significantly different to their original PD scores. The Spearman correlation coefficient revealed a significant negative association between their ability to recognize their original PD and their Modified Somatic Perceptions Questionnaire scores. Limitations: The patients in the study presented with relatively mild CNP, and the results may not be generalized to those with more severe symptoms. Conclusions: People with CNP are generally able to identify their own PD but that their ability to recognize their original PD is negatively correlated with the extent of somatic awareness

    Performance of the Fully Digital FPGA-based Front-End Electronics for the GALILEO Array

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    In this work we present the architecture and results of a fully digital Front End Electronics (FEE) read out system developed for the GALILEO array. The FEE system, developed in collaboration with the Advanced Gamma Tracking Array (AGATA) collaboration, is composed of three main blocks: preamplifiers, digitizers and preprocessing electronics. The slow control system contains a custom Linux driver, a dynamic library and a server implementing network services. The digital processing of the data from the GALILEO germanium detectors has demonstrated the capability to achieve an energy resolution of 1.53 per mil at an energy of 1.33 MeV.Comment: 5 pages, 6 figures, preprint version of IEEE Transactions on Nuclear Science paper submitted for the 19th IEEE Real Time Conferenc
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