1,523 research outputs found

    Contextual information and assessor characteristics in complex question answering

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    The ciqa track investigates the role of interaction in answering complex questions: questions that relate two or more entities by some specified relationship. In our submission to the first ciqa track we were interested in the interplay between groups of variables: variables describing the question creators, the questions asked and the presentation of answers to the questions. We used two interaction forms - html questionnaires completed before answer assessment - to gain contextual information from the answer assessors to better understand what factors influence assessors when judging retrieved answers to complex questions. Our results indicate the importance of understanding the assessor's personal relationship to the question - their existing topical knowledge for example - and also the presentation of the answers - contextual information about the answer to aid in the assessment of the answer

    Discovery of Raman-scattered lines in the massive luminous emission-line star LHA 115-S 18

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    LHA 115-S 18 is a very peculiar emission-line star exhibiting the B[e] phenomenon. Located in the Small Magellanic Cloud, its spectrum shows features of an extremely wide range of excitation and ionization stages, extending from highly ionized atomic lines (Si IV, C IV, He II) in the UV and optical regions to molecular emission bands of CO and TiO in the optical and IR regions. The most distinguishing spectral characteristic of LHA 115-S 18 is the high variability detected in the He II {\lambda}4686 emission line, which can be a very conspicuous or completely invisible feature. In this work, we report on another peculiarity of LHA 115-S 18. From high-resolution optical spectra taken between 2000 and 2008, we discovered the appearance and strengthening of two emission features at {\lambda}6825 \AA, and {\lambda}7082 \AA,, which we identified as Raman-scattered lines. This is the first time these lines have been detected in the spectrum of a massive luminous B[e] star. As the classification of LHA 115-S 18 is highly controversial, we discuss how the discovery of the appearance of Raman-scattered lines in this peculiar star might help us to solve this puzzle.Comment: Letter accepted for publication in MNRAS. 5 pages, 3 figure

    Detection of curved lines with B-COSFIRE filters: A case study on crack delineation

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    The detection of curvilinear structures is an important step for various computer vision applications, ranging from medical image analysis for segmentation of blood vessels, to remote sensing for the identification of roads and rivers, and to biometrics and robotics, among others. %The visual system of the brain has remarkable abilities to detect curvilinear structures in noisy images. This is a nontrivial task especially for the detection of thin or incomplete curvilinear structures surrounded with noise. We propose a general purpose curvilinear structure detector that uses the brain-inspired trainable B-COSFIRE filters. It consists of four main steps, namely nonlinear filtering with B-COSFIRE, thinning with non-maximum suppression, hysteresis thresholding and morphological closing. We demonstrate its effectiveness on a data set of noisy images with cracked pavements, where we achieve state-of-the-art results (F-measure=0.865). The proposed method can be employed in any computer vision methodology that requires the delineation of curvilinear and elongated structures.Comment: Accepted at Computer Analysis of Images and Patterns (CAIP) 201

    Intra-assessor consistency in question answering

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    In this paper we investigate the consistency of answer assessment in a complex question answering task examining features of assessor consistency, types of answers and question type

    Characterisation of an analogue liquid for hydrodynamic studies of gas-ionic liquid flows

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    Ionic liquids are liquid salts at low temperatures (normally less than 100°C). They are powerful solvents with very low vapour pressure. They have great potentials in many applications such as gas absorption and chemical synthesis. However, they are expensive. This limits extensive studies towards establishing phenomenological models. To address this limitation, an analogue liquid, with properties similar to an ionic liquid, has been identified which on the grounds of cost and safety appears to be suitable. In this paper, the hydrodynamic behaviour of an ionic liquid in a bubble column is compared with those of water and other liquids with similar physical properties. Average gas holdup, bubble coalescence, bubble size and specific interfacial area with different liquids are examined. Gas hold-up was determined by monitoring the change of conductivity between two flush mounted rings. The differences in bubble size and coalescence are revealed by analysing the stills taken from a high speed video camera. The dominant flow pattern in a small diameter column with ionic liquids or other fluids having similar viscosity is slug flow. The small bubbles in the liquid slugs make a smaller contribution to the specific interfacial area than Taylor bubbles. It is observed that Taylor bubbles can coalesce. The hydrodynamics of an ionic liquid in a bubble column can be estimated from that of a fluid with similar physical properties

    Moderate hypothermia within 6 h of birth plus inhaled xenon versus moderate hypothermia alone after birth asphyxia (TOBY-Xe): a proof-of-concept, open-label, randomised controlled trial

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    Background Moderate cooling after birth asphyxia is associated with substantial reductions in death and disability, but additional therapies might provide further benefit. We assessed whether the addition of xenon gas, a promising novel therapy, after the initiation of hypothermia for birth asphyxia would result in further improvement. Methods Total Body hypothermia plus Xenon (TOBY-Xe) was a proof-of-concept, randomised, open-label, parallel-group trial done at four intensive-care neonatal units in the UK. Eligible infants were 36–43 weeks of gestational age, had signs of moderate to severe encephalopathy and moderately or severely abnormal background activity for at least 30 min or seizures as shown by amplitude-integrated EEG (aEEG), and had one of the following: Apgar score of 5 or less 10 min after birth, continued need for resuscitation 10 min after birth, or acidosis within 1 h of birth. Participants were allocated in a 1:1 ratio by use of a secure web-based computer-generated randomisation sequence within 12 h of birth to cooling to a rectal temperature of 33·5°C for 72 h (standard treatment) or to cooling in combination with 30% inhaled xenon for 24 h started immediately after randomisation. The primary outcomes were reduction in lactate to N-acetyl aspartate ratio in the thalamus and in preserved fractional anisotropy in the posterior limb of the internal capsule, measured with magnetic resonance spectroscopy and MRI, respectively, within 15 days of birth. The investigator assessing these outcomes was masked to allocation. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00934700, and with ISRCTN, as ISRCTN08886155. Findings The study was done from Jan 31, 2012, to Sept 30, 2014. We enrolled 92 infants, 46 of whom were randomly assigned to cooling only and 46 to xenon plus cooling. 37 infants in the cooling only group and 41 in the cooling plus xenon group underwent magnetic resonance assessments and were included in the analysis of the primary outcomes. We noted no significant differences in lactate to N-acetyl aspartate ratio in the thalamus (geometric mean ratio 1·09, 95% CI 0·90 to 1·32) or fractional anisotropy (mean difference −0·01, 95% CI −0·03 to 0·02) in the posterior limb of the internal capsule between the two groups. Nine infants died in the cooling group and 11 in the xenon group. Two adverse events were reported in the xenon group: subcutaneous fat necrosis and transient desaturation during the MRI. No serious adverse events were recorded. Interpretation Administration of xenon within the delayed timeframe used in this trial is feasible and apparently safe, but is unlikely to enhance the neuroprotective effect of cooling after birth asphyxia

    A Search for Wolf-Rayet Stars in the Small Magellanic Cloud

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    We conducted an extensive search for Wolf-Rayet stars (W-Rs) in the SMC, using the same interference filter imaging techniques that have proved successful in finding W-Rs in more distant members of the Local Group. Photometry of some 1.6 million stellar images resulted in some 20 good candidates, which we then examined spectroscopically. Two of these indeed proved to be newly found W-Rs, bringing the total known in the SMC from 9 to 11. Other finds included previously unknown Of-type stars (one as early as O5f?p)),the recovery of the Luminous Blue Variable S18, and the discovery of a previously unknown SMC symbiotic star. More important, however, is the fact that there does not exist a significant number of W-Rs waiting to be discovered in the SMC. The number of W-Rs in the SMC is a factor of 3 lower than in the LMC (per unit luminosity), and we argue this is the result of the SMC's low metallicity on the evolution of the most massive stars.Comment: Accepted by Astrophysical Journal. Postscript version available via ftp.lowell.edu/pub/massey/smcwr.ps.gz Revised version contains slightly revised spectral types for the Of stars but is otherwise unchange

    Terminal velocities of luminous, early-type SMC stars

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    Ultraviolet spectra from the Space Telescope Imaging Spectrograph (STIS) are used to determine terminal velocities for 11 O and B-type giants and supergiants in the Small Magellanic Cloud (SMC) from the Si IV and C IV resonance lines. Using archival data from observations with the Goddard High-Resolution Spectrograph and the International Ultraviolet Explorer telescope, terminal velocities are obtained for a further five B-type supergiants. We discuss the metallicity dependence of stellar terminal velocities, finding no evidence for a significant scaling between Galactic and SMC metallicities for Teff < 30,000 K, consistent with the predictions of radiation driven wind theory for supergiant stars. A comparison of the v/vescv_\infty / v_{esc} ratio between the SMC and Galactic samples, while consistent with the above statement, emphasizes that the uncertainties in the distances to galactic O-stars are a serious obstacle to a detailed comparison with theory. For the SMC sample there is considerable scatter in this ratio at a given effective temperature, perhaps indicative of uncertainties in stellar masses.Comment: 28 pages, 8 figures, accepted by ApJ; minor revisions prior to acceptanc
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