96 research outputs found

    Ontologies as bridges between data sources and user queries: the KNOWMAK project experience

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    This paper describes ongoing work in the KNOWMAK project, which aims to develop a webbased tool providing interactive visualisations and state-of-the-art indicators on knowledge cocreation in the European research area. One of the main novel developments in this work is the use of ontologies to act as a bridge between the data sources (research projects, patents and publications) and user queries, in order to address the problems of mapping between heterogenous data sources with different vocabularies while still maintaining a level of standardization necessary for summarising the information required to provide informative views about the highly dynamic S&T landscape

    Who cares about sarcastic tweets? Investigating the impact of sarcasm on sentiment analysis

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    Sarcasm is a common phenomenon in social media, and is inherently difficult to analyse, not just automatically but often for humans too. It has an important effect on sentiment, but is usually ignored in social media analysis, because it is considered too tricky to handle. While there exist a few systems which can detect sarcasm, almost no work has been carried out on studying the effect that sarcasm has on sentiment in tweets, and on incorporating this into automatic tools for sentiment analysis. We perform an analysis of the effect of sarcasm scope on the polarity of tweets, and have compiled a number of rules which enable us to improve the accuracy of sentiment analysis when sarcasm is known to be present. We consider in particular the effect of sentiment and sarcasm contained in hashtags, and have developed a hashtag tokeniser for GATE, so that sentiment and sarcasm found within hashtags can be detected more easily. According to our experiments, the hashtag tokenisation achieves 98% Precision, while the sarcasm detection achieved 91% Precision and polarity detection 80%

    Challenges of Evaluating Sentiment Analysis Tools on Social Media

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    This paper discusses the challenges in carrying out fair comparative evaluations of sentiment analysis systems. Firstly, these are due to differences in corpus annotation guidelines and sentiment class distribution. Secondly, different systems often make different assumptions about how to interpret certain statements, e.g. tweets with URLs. In order to study the impact of these on evaluation results, this paper focuses on tweet sentiment analysis in particular. One existing and two newly created corpora are used, and the performance of four different sentiment analysis systems is reported; we make our annotated datasets and sentiment analysis applications publicly available. We see considerable variations in results across the different corpora, which calls into question the validity of many existing annotated datasets and evaluations, and we make some observations about both the systems and the datasets as a result

    An Investigation of the Soft Pion Relation in Quenched Lattice QCD

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    A lattice determination of the form factor and decay constants for the semileptonic decay of heavy pseudoscalar (PS) mesons at zero recoil is presented from which the soft pion relation is satisfied. Chiral extrapolation of the form factor is performed at constant q2q^2. Pole dominance is used to extrapolate the form factor in heavy quark mass. At the B mass, the form factor at zero recoil lies somewhat below the ratio of decay constants; the relation remains satisfied within error.Comment: 3 pages, 2 figure

    Excited nucleon spectrum using a non-perturbatively improved clover fermion action

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    We discuss the extraction of negative-parity baryon masses from lattice QCD calculations. The mass of the lowest-lying negative-parity J=1/2J = 1/2^{-} state is computed in quenched lattice QCD using an O(a){\cal O}(a)-improved clover fermion action, and a splitting found with the nucleon mass. The calculation is performed on two lattice volumes, and three lattice spacings enabling a study of both finite-volume and finite-lattice-spacing uncertainties. A measurement of the first excited radial excitation of the nucleon finds a mass considerably larger than that of the negative-parity ground state, in accord with other lattice determinations but in disagreement with experiment. Results are also presented for the lightest negative-parity I=3/2I=3/2 state.Comment: 7 pages, 5 figures, uses espcrc2. Talk presented at Workshop on Lattice Hadron Physics, Colonial Club Resort, Cairns, Australia, July 9-18, 2001. Corrected error in determination of mass of excited, positive-parity nucleon resonanc

    Negative-parity Baryon Masses using an O(a)-improved Fermion Action

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    We present a calculation of the mass of the lowest-lying negative-parity J=1/2- state in quenched QCD. Results are obtained using a non-perturbatively O(a)-improved clover fermion action, and a splitting is found between the mass of the nucleon and its parity partner. The calculation is performed on two lattice volumes and at three lattice spacings, enabling a study of both finite-volume and finite lattice-spacing uncertainties. A comparison is made with results obtained using the unimproved Wilson fermion action.Comment: 13 pages, 8 figures, revtex Version accepted for publication in Physics Letters B. Some changes to discussion of chiral extrapolations; primary results unchange

    First observation of the decay Bˉs0D0K0\bar{B}^0_s \to D^0 K^{*0} and a measurement of the ratio of branching fractions B(Bˉs0D0K0)B(Bˉ0D0ρ0)\frac{{\cal B}(\bar{B}^0_s \to D^0 K^{*0})}{{\cal B}(\bar{B}^0 \to D^0 \rho^0)}

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    The first observation of the decay Bˉs0D0K0\bar{B}^0_s \to D^0 K^{*0} using pppp data collected by the LHCb detector at a centre-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 36 pb1^{-1}, is reported. A signal of 34.4±6.834.4 \pm 6.8 events is obtained and the absence of signal is rejected with a statistical significance of more than nine standard deviations. The Bˉs0D0K0\bar{B}^0_s \to D^0 K^{*0} branching fraction is measured relative to that of Bˉ0D0ρ0\bar{B}^0 \to D^0 \rho^0: B(Bˉs0D0K0)B(Bˉ0D0ρ0)=1.48±0.34±0.15±0.12\frac{{\cal B}(\bar{B}^0_s \to D^0 K^{*0})}{{\cal B}(\bar{B}^0 \to D^0 \rho^0)} = 1.48 \pm 0.34 \pm 0.15 \pm 0.12, where the first uncertainty is statistical, the second systematic and the third is due to the uncertainty on the ratio of the B0B^0 and Bs0B^0_s hadronisation fractions.Comment: 10 pages, 3 figures, submitted to Phys. Lett. B; ISSN 0370-269
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