Digging by Debating: Linking massive datasets to specific arguments

We will develop and implement a multi-scale workbench, called "InterDebates", with the goal of digging into data provided by hundreds of thousands, eventually millions, of digitized books, bibliographic databases of journal articles, and comprehensive reference works written by experts. Our hypotheses are: that detailed and identifiable arguments drive many aspects of research in the sciences and the humanities; that argumentative structures can be extracted from large datasets using a mixture of automated and social computing techniques; and, that the availability of such analyses will enable innovative interdisciplinary research, and may also play a role in supporting better-informed critical debates among students and the general public. A key challenge tackled by this project is thus to uncover and represent the argumentative structure of digitized documents, allowing users to find and interpret detailed arguments in the broad semantic landscape of books and articles

From Big Data to Argument Analysis and Automated Extraction: A Selective Study of Argument in the Philosophy of Animal Psychology from the Volumes of the Hathi Trust Collection

The Digging by Debating (DbyD) project aimed to identify, extract, model, map and visualise philosophical arguments in very large text repositories such as the Hathi Trust. The project has: 1) developed a method for visualizing points of contact between philosophy and the sciences; 2) used topic modeling to identify the volumes, and pages within those volumes, which are ‘rich’ in a chosen topic; 3) used a semiformal discourse analysis technique to manually identify key arguments in the selected pages; 4) used the OVA argument mapping tool to represent and map the key identified arguments and provide a framework for comparative analysis; 5) devised and used a novel analysis framework applied to the mapped arguments covering role, content and source of propositions, and the importance, context and meaning of arguments; 6) created a prototype tool for identifying propositions, using naive Bayes classifiers, and for identifying argument structure in chosen texts, using propositional similarity; 7) created tools to apply topic modeling to tasks of rating similarity of papers in the PhilPapers repository. The methods from 1 to 5 above, have enabled us to locate and extract the key arguments from each text. It is significant that, in applying the methods, a nonexpert with limited or no domain knowledge of philosophy has both identified the volumes of interest from a key ‘Big Data Set’ (Hathi Trust) AND identified key arguments within these texts. This provided several key insights about the nature and form of arguments in historical texts, and is a proofofconcept design for a tool that will be usable by scholars. We have further created a dataset with which to train and test prototype tools for both proposition and argument extraction. Though at an early stage, these preliminary results are promising given the complexity of the task. Specifically, we have prototyped a set of tools and methods that allow scholars to move between macroscale, global views of the distributions of philosophical themes in such repositories, and microscale analyses of the arguments appearing on specific pages in texts belonging to the repository. Our approach spans bibliographic analysis, science mapping, and LDA topic modeling conducted at Indiana University and machineassisted argument markup into Argument Interchange Format (AIF) using the OVA (Online Visualization of Argument) tool from the University of Dundee, where the latter has been used to analyse and represent arguments by the team based at the University of East London, who also performed a detailed empirical analysis of arguments in selected texts. This work has been articulated as a proof of concept tool – linked to the repository PhilPapers – designed by members linked to the University of London. This project is showing for the first time how big data text processing techniques can be combined with deep structural analysis to provide researchers and students with navigation and interaction tools for engaging with the large and rich resources provided by datasets such as the Hathi Trust and PhilPapers. Ultimately our efforts show how the computational humanities can bridge the gulf between the “big data” perspective of firstgeneration digital humanities and the close readings of text that are the “bread and butter” of more traditional scholarship in the humanities

Lambda Boo stars with composite spectra

We examine the large sample of lambda Boo candidates collected in Table 1 of Gerbaldi et al. (2003) to see how many of them show composite spectra. Of the 132 lambda Boo candidates we identify 22 which definitely show composite spectra and 15 more for which there are good reasons to suspect a composite spectrum. The percentage of lambda Boo candidates with composite spectra is therefore > 17 and possibly considerably higher. For such stars the lambda Boo classification should be reconsidered taking into account the fact that their spectra are composite. We argue that some of the underabundances reported in the literature may simply be the result of the failure to consider the composite nature of the spectra. This leads to the legitimate suspicion that some, if not all, the lambda Boo candidates are not chemically peculiar at all. A thorough analysis of even a single one of the lambda Boo candidates with composite spectra, in which the composite nature of the spectrum is duly considered, which would demonstrate that the chemical peculiarities persist, would clear the doubt we presently have that the stars with composite spectra may not be lambda Boo at all.Comment: Accepted for publication by A&A on June 3rd 200

Imaging and Modeling Rapidly Rotating Stars: Alpha Cephei and Alpha Ophiuchi

We present sub-milliarcseond resolution imaging and modeling of two nearby rapid rotators Alpha Cephei and Alpha Ophiuchi, obtained with the CHARA array - the largest optical/IR interferometer in the world. Incorporating a gravity darkening model, we are able to determine the inclination, the polar and equatorial radius and temperature, as well as the fractional rotation speed of the two stars with unprecedented precision. The polar and equatorial regions of the two stars have ~2000K temperature gradient, causing their apparent temperatures and luminosities to be dependent on their viewing angles. Our modeling allow us to determine the true effective temperatures and luminosities of Alpha Cep and Alpha Oph, permitting us to investigate their true locations on the H-R diagram. These properties in turn give us estimates of the masses and ages of the two stars within a few percent of error using stellar evolution models. Also, based on our gravity darkening modeling, we propose a new method to estimate the masses of single stars in a more direct way through Vsin(i) measurements and precise geometrical constraint. Lastly, we investigate the degeneracy between the inclination and the gravity darkening coefficient, which especially affects the modeling of Alpha Oph. Although incorporating Vsin(i) has lifted the degeneracy to some extent, higher resolution observations are still needed to further constrain the parameters independently.Comment: 36 pages, 14 figures, accepted by Ap

The VAST Survey - I. Companions and the unexpected X-ray detection of B6-A7 stars

With an adaptive optics imaging survey of 148 B6-A7 stars, we have tested the hypothesis that unresolved lower-mass companions are the source of the unexpected X-ray detections of stars in this spectral type range. The sample is composed of 63 stars detected in X-rays within the ROSAT All-Sky Survey and 85 stars that form a control sample; both subsets have the same restricted distribution of spectral type, age, X-ray sensitivity and separation coverage. A total of 68 companion candidates are resolved with separations ranging from 0.3" to 26.2", with 23 new detections. The multiple star frequency of the X-ray sample based on companions resolved within the ROSAT error ellipse is found to be 43 (+6,-6)%. The corresponding control sample multiple star frequency is three times lower at 12 (+4,-3)% -- a difference of 31\pm7%. These results are presented in the first of a series of papers based on our Volume-limited A-Star (VAST) survey -- a comprehensive study of the multiplicity of A-type stars.Comment: Accepted for publication in Monthly Notices of the Royal Astronomical Societ

Chromosphere of K giant stars Geometrical extent and spatial structure detection

We aim to constrain the geometrical extent of the chromosphere of non-binary K giant stars and detect any spatial structures in the chromosphere. We performed observations with the CHARA interferometer and the VEGA beam combiner at optical wavelengths. We observed seven non-binary K giant stars. We measured the ratio of the radii of the photosphere to the chromosphere using the interferometric measurements in the Halpha and the Ca II infrared triplet line cores. For beta Ceti, spectro-interferometric observations are compared to an non-local thermal equilibrium (NLTE) semi-empirical model atmosphere including a chromosphere. The NLTE computations provide line intensities and contribution functions that indicate the relative locations where the line cores are formed and can constrain the size of the limb-darkened disk of the stars with chromospheres. We measured the angular diameter of seven K giant stars and deduced their fundamental parameters: effective temperatures, radii, luminosities, and masses. We determined the geometrical extent of the chromosphere for four giant stars. The chromosphere extents obtained range between 16% to 47% of the stellar radius. The NLTE computations confirm that the Ca II/849 nm line core is deeper in the chromosphere of ? Cet than either of the Ca II/854 nm and Ca II/866 nm line cores. We present a modified version of a semi-empirical model atmosphere derived by fitting the Ca II triplet line cores of this star. In four of our targets, we also detect the signature of a differential signal showing the presence of asymmetries in the chromospheres. Conclusions. It is the first time that geometrical extents and structure in the chromospheres of non-binary K giant stars are determined by interferometry. These observations provide strong constrains on stellar atmosphere models.Comment: 10 pages, 12 figure

HD 181068: A Red Giant in a Triply-Eclipsing Compact Hierarchical Triple System

Hierarchical triple systems comprise a close binary and a more distant component. They are important for testing theories of star formation and of stellar evolution in the presence of nearby companions. We obtained 218 days of Kepler photometry of HD 181068 (magnitude of 7.1), supplemented by groundbased spectroscopy and interferometry, which show it to be a hierarchical triple with two types of mutual eclipses. The primary is a red giant that is in a 45-day orbit with a pair of red dwarfs in a close 0.9-day orbit. The red giant shows evidence for tidally-induced oscillations that are driven by the orbital motion of the close pair. HD 181068 is an ideal target for studies of dynamical evolution and testing tidal friction theories in hierarchical triple systems.Comment: 22 pages, including supporting on-line material. This is the author's version of the work. It is posted here by permission of the AAAS for personal use, not for redistribution. The definitive version was published in Science Vol. 332 no. 6026 pp. 216-218 (8 April 2011), doi:10.1126/science.1201762. http://www.sciencemag.org/content/332/6026/216.ful

Visual binaries among high-mass stars - An adaptive optics survey of OB stars in the NGC 6611 cluster

We have searched for visual binaries with projected separations in the range 200-3000 AU (0.1"-1.5") among a sample of 96 stars in the massive young NGC 6611 cluster, 60 of them being subsequently identified as high probability cluster members of mainly OB spectral type. This is the first visual binary survey among such a large and homogeneous sample of high-mass stars. We find an uncorrected binary frequency of 18+/-6% over the surveyed separation range. Considering only binaries with mass ratios q>0.1, we find that OB stars in NGC 6611 host more companions than solar-type field stars. We derive mass ratios for the detected binaries from their near-infrared flux ratios and conclude that about half of the detected binaries have q<0.2, which does not contradict the assumption that companion masses are randomly drawn from the initial mass function. There is no evidence in our sample that wide-binary properties depend upon the mass of the primary star. The high frequency of massive binaries in a cluster as rich as NGC 6611 and the lack of a strong mass dependence of their properties are difficult to reconcile with the scenario whereby massive stars form as the result of mergers of smaller stars. The canonical protostellar accretion scenario together with cloud fragmentation, on the other hand, can naturally explain most of the observed binary properties, although the very high stellar density in the protocluster is likely to require significant modification to that picture as well.Comment: Accepted for publication in A&A, LaTeX2e, 15 pages, 5 embedded figure

The Calar Alto lunar occultation program: update and new results

We present an update of the lunar occultation program which is routinely carried out in the near-IR at the Calar Alto Observatory. A total of 350 events were recorded since our last report (Fors et al. 2004). In the course of eight runs we have observed, among others, late-type giants, T-Tauri stars, and infrared sources. Noteworthy was a passage of the Moon close to the galactic center, which produced a large number of events during just a few hours in July 2004. Results include the determinations of the angular diameter of RZ Ari, and the projected separations and brightness ratios for one triple and 13 binary stars, almost all of which representing first time detections. Projected separations range from 0.09arcsec to 0.007arcsec. We provide a quantitative analysis of the performance achieved in our observations in terms of angular resolution and sensitivity, which reach about 0.003arcsec and K~8.5mag, respectively. We also present a statistical discussion of our sample, and in particular of the frequency of detection of binaries among field stars.Comment: 8 pages, 2 figures. Accepted for publication in A&