497 research outputs found

    Toward Semantics-aware Representation of Digital Business Processes

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    An extended enterprise (EE) can be described by a set of models each representing a specific aspect of the EE. Aspects can for example be the process flow or the value description. However, different models are done by different people, which may use different terminology, which prevents relating the models. Therefore, we propose a framework consisting of process flow and value aspects and in addition a static domain model with structural and relational components. Further, we outline the usage of the static domain model to enable relating the different aspects

    Spectrophotometric Redshifts. A New Approach to the Reduction of Noisy Spectra and its Application to GRB090423

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    We have developed a new method, close in philosophy to the photometric redshift technique, which can be applied to spectral data of very low signal-to-noise ratio. Using it we intend to measure redshifts while minimising the dangers posed by the usual extraction techniques. GRB afterglows have generally very simple optical spectra over which the separate effects of absorption and reddening in the GRB host, the intergalactic medium, and our own Galaxy are superimposed. We model all these effects over a series of template afterglow spectra to produce a set of clean spectra that reproduce what would reach our telescope. We also model carefully the effects of the telescope-spectrograph combination and the properties of noise in the data, which are then applied on the template spectra. The final templates are compared to the two-dimensional spectral data, and the basic parameters (redshift, spectral index, Hydrogen absorption column) are estimated using statistical tools. We show how our method works by applying it to our data of the NIR afterglow of GRB090423. At z ~ 8.2, this was the most distant object ever observed. We use the spectrum taken by our team with the Telescopio Nazionale Galileo to derive the GRB redshift and its intrinsic neutral Hydrogen column density. Our best fit yields z=8.4^+0.05/-0.03 and N(HI)<5x10^20 cm^-2, but with a highly non-Gaussian uncertainty including the redshift range z [6.7, 8.5] at the 2-sigma confidence level. Our method will be useful to maximise the recovered information from low-quality spectra, particularly when the set of possible spectra is limited or easily parameterisable while at the same time ensuring an adequate confidence analysis.Comment: 6 pages, 6 figures. Accepted for publication in Astronomy and Astrophysic

    Preliminary results from antarctic albedo from remote sensing observations

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    The aim of the study is to analyse the surface albedo of the Ant-arctica and investigate eventual signals of variations in space and time between summer 2000/2001 and 2011/2012 by means of the GLASS albedo product. We followed a step-by-step procedure from micro- to macro-scale. At first, we analysed 95 glaciers around the continent, and we found limited temporal variability. Then, looking at spatial varia-tions, we divided Antarctica based on oceanic basins and by continen-tality. We found spatial signals, since mean albedo values range between 0.79 (Pacific and Atlantic basins) and 0.82 (Indian basin) and between 0.76 (along the shore) and 0.81 (inner continent). An increasing vari-ability was found from the inner continent to the shore, and heteroge-neous patterns among the basins, most likely due to meteorological and environmental conditions (mainly: temperature, precipitation, katabatic winds). Finally, the general patterns observed (considering the specific gla-ciers, the three basins and the three continentality sectors) were verified by the analysis of the whole continent and we did not find a significant change of summer averages over time, as they range between 0.79 and 0.80

    The Swift X-ray Telescope Cluster Survey II. X-ray spectral analysis

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    (Abridged) We present a spectral analysis of a new, flux-limited sample of 72 X-ray selected clusters of galaxies identified with the X-ray Telescope (XRT) on board the Swift satellite down to a flux limit of ~10-14 erg/s/cm2 (SWXCS, Tundo et al. 2012). We carry out a detailed X-ray spectral analysis with the twofold aim of measuring redshifts and characterizing the properties of the Intra-Cluster Medium (ICM). Optical counterparts and spectroscopic or photometric redshifts are obtained with a cross-correlation with NED. Additional photometric redshifts are computed with a dedicated follow-up program with the TNG and a cross-correlation with the SDSS. We also detect the iron emission lines in 35% of the sample, and hence obtain a robust measure of the X-ray redshift zX. We use zX whenever the optical redshift is not available. Finally, for all the sources with measured redshift, background-subtracted spectra are fitted with a mekal model. We perform extensive spectral simulations to derive an empirical formula to account for fitting bias. The bias-corrected values are then used to investigate the scaling properties of the X-ray observables. Overall, we are able to characterize the ICM of 46 sources. The sample is mostly constituted by clusters with temperatures between 3 and 10 keV, plus 14 low-mass clusters and groups with temperatures below 3 keV. The redshift distribution peaks around z~0.25 and extends up to z~1, with 60% of the sample at 0.1<z<0.4. We derive the Luminosity-Temperature relation for these 46 sources, finding good agreement with previous studies. The quality of the SWXCS sample is comparable to other samples available in the literature and obtained with much larger X-ray telescopes. Our results have interesting implications for the design of future X-ray survey telescopes, characterised by good-quality PSF over the entire field of view and low background.Comment: 27 pages, 15 figures; minor typos corrected. To be published in A&A, Volume 567, July 2014. Websites of the SWXCS project: http://www.arcetri.astro.it/SWXCS/ and http://swxcs.ustc.edu.cn

    A comparison of personality traits of gifted word learner and typical border collies

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    While personality and cognition are distinct domains, some personality traits may affect the capacity for problem-solving. It was suggested that there is a positive association between the Playfulness trait and problem-solving performance in humans. Studies on giftedness (extremely good capacity in the case of a specific skill), typically aimed to reveal the genetic, experiential, and mental origins of such extreme inter-individual variation. We exploited recent findings on giftedness in a specific cognitive skill, object label learning, in dogs to explore the potential association between this exceptional skill and personality traits. We administered the Dog Personality Questionnaire to 21 gifted dog owners and compared the personality traits of their dogs to those of matched samples of 43 Hungarian and 101 Austrian typical dogs, i.e., dogs lacking this exceptional capacity. Since most Gifted Word Learner dogs are Border collies, we restricted our analysis to dogs of this breed. We hypothesized that the Gifted Word Learner dogs may show higher levels of Playfulness. As expected, we found that the gifted Border collies were rated as more playful than both the Hungarian and Austrian typical ones. Our results suggest that an extremely high level of Playfulness is associated with giftedness in a specific cognitive trait in dogs: the capacity to learn object verbal labels, thus opening new possibilities for comparative research on the relationship between giftedness and personality

    Testing the gamma-ray burst variability/peak luminosity correlation on a Swift homogeneous sample

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    We test the gamma-ray burst correlation between temporal variability and peak luminosity of the γ\gamma-ray profile on a homogeneous sample of 36 Swift/BAT GRBs with firm redshift determination. This is the first time that this correlation can be tested on a homogeneous data sample. The correlation is confirmed, as long as the 6 GRBs with low luminosity (<5x10^{50} erg s^{-1} in the rest-frame 100-1000 keV energy band) are ignored. We confirm that the considerable scatter of the correlation already known is not due to the combination of data from different instruments with different energy bands, but it is intrinsic to the correlation itself. Thanks to the unprecedented sensitivity of Swift/BAT, the variability/peak luminosity correlation is tested on low-luminosity GRBs. Our results show that these GRBs are definite outliers.Comment: Accepted for Publication in MNRAS. 10 pages, 5 figures, 3 table

    Optical and infrared photometry of the blazar PKS0537-441

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    We present a large collection of photometric data on the Blazar PKS 0537-441 in the VRIJHK bands taken in 2004-2009. At least three flare-like episodes with months duration, and >3 mag amplitude are apparent. The spectral energy distribution is consistent with a power law, and no indication of a thermal component is found. We searched for short time scale variability, and an interesting event was identified in the J band, with a duration of ~25 minutes.Comment: 10 pages, 3 figures, in press in ApJ
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