258 research outputs found
Building Quality Assurance into Metadata Creation: an Analysis based on the Learning Objects and e-Prints Communities of Practice
No full textThis paper challenges some of the assumptions underlying the metadata creation process in the context of two communities of practice, based around learning object repositories and open e-Print archives. The importance of quality assurance for metadata creation is discussed and evidence from the literature, from the practical experiences of repositories and archives, and from related research and practices within other communities is presented. Issues for debate and further investigation are identified, formulated as a series of key research questions. Although there is much work to be done in the area of quality assurance for metadata creation, this paper represents an important first step towards a fuller understanding of the subject.
RoMEO Studies 4: An analysis of Journal publishers' Copyright Agreements
No full textThis article is the fourth in a series of six emanating from the UK JISC-funded RoMEO Project (Rights Metadata for Open archiving). It describes an analysis of 80 scholarly journal publishers’ copyright agreements with a particular view to their effect on author self-archiving. 90% of agreements asked for copyright transfer and 69% asked for it prior to refereeing the paper. 75% asked authors to warrant that their work had not been previously published although only two explicitly stated that they viewed self-archiving as prior publication. 28.5% of agreements provided authors with no usage rights over their own paper. Although 42.5% allowed self-archiving in some format, there was no consensus on the conditions under which self-archiving could take place. The article concludes that author-publisher copyright agreements should be reconsidered by a working party representing the needs of both partie
Self-archiving practice and the influence of publisher policies in the social sciences
No full textAuthors in different disciplines exhibit very different behaviours on the so-called ‘green’ road to open access, i.e. self-archiving. This study looks at the self-archiving behaviour of authors publishing in leading journals in six social science disciplines. It tests the hypothesis that authors are self-archiving according to the norms of their respective disciplines rather than following self-archiving policies of publishers, and that, as a result, they are self-archiving significant numbers of publisher PDF versions. It finds significant levels of
self-archiving, as well as significant self-archiving of
the publisher PDF version, in all the disciplines
investigated. Publishers’ self-archiving policies have
no influence on author self-archiving practice
Exploring the substellar temperature regime down to similar to 550K
No full textWe report the discovery of three very late T dwarfs in the UKIRT Infrared Deep Sky Survey (UKIDSS) Third Data Release: ULAS J101721.40+011817.9 (ULAS1017), ULAS J123828.51+095351.3 (ULAS1238) and ULAS J133553.45+113005.2 (ULAS1335). We detail optical and near-infrared (NIR) photometry for all three sources, and mid-IR photometry for ULAS1335. We use NIR spectra of each source to assign spectral types T8p (ULAS1017), T8.5 (ULAS1238) and T9 (ULAS1335) to these objects. ULAS1017 is classed as a peculiar T8 (T8p) due to appearing as a T8 dwarf in the J band, whilst exhibiting H- and K-band flux ratios consistent with a T6 classification. Through comparison to BT-Settl model spectra we estimate that ULAS1017 has 750K less than or similar to T(eff) less than or similar to 850 K, and 5.0 less than or similar to log g(cm s(-2)) less than or similar to 5.5, assuming solar metallicity. This estimate for gravity is degenerate with varying metallicity. We estimate that ULAS1017 has an age of 1.6-15 Gyr, a mass of 33-70M(J) and lies at a distance of 31-54 pc. We do not estimate atmospheric parameters for ULAS1238 due to a lack of K-band photometry. We extend the unified scheme of Burgasser et al. to the type T9 and suggest the inclusion of the W(J) index to replace the now saturated J-band indices. We propose ULAS1335 as the T9 spectral type standard. ULAS1335 is the same spectral type as ULAS J003402.77-005206.7 and CFBDS J005910.90-011401.3. We argue that given the similarity of the currently known > T8 dwarfs to the rest of the T dwarf sequence, the suggestion of the Y0 spectral class for these objects is premature. Comparison of model spectra with that of ULAS1335 suggest a temperature below 600 K, possibly combined with low gravity and/or high metallicity. We find ULAS1335 to be extremely red in NIR to mid-IR colours, with H - [4.49] = 4.34 +/- 0.04. This is the reddest NIR to mid-IR colour yet observed for a T dwarf. The NIR to mid-IR spectral energy distribution of ULAS1335 further supports T(eff) < 600 K, and we estimate T(eff) similar to 550-600 K for ULAS1335. We estimate that ULAS1335 has an age of 0.6-5.3 Gyr, a mass of 15-31M(J) and lies at a distance of 8-12 pc
Red Optical Planet Survey: a new search for habitable earths in the southern sky
No full textWe present the first results from our Red Optical Planet Survey to search for low-mass planets orbiting late-type dwarfs (M5.5VM9V) in their habitable zones. Our observations with the red arm of the Magellan Inamori Kyocera Echelle spectrograph (0.50.9 m) at the 6.5-m Magellan Clay telescope at Las Campanas Observatory indicate that =92 per cent of the flux lies beyond 0.7 m. We use a novel approach that is essentially a hybrid of the simultaneous iodine and ThAr methods for determining precision radial velocities. We apply least squares deconvolution to obtain a single high signal-to-noise ratio (S/N) stellar line for each spectrum and cross-correlate against the simultaneously observed telluric line profile, which we derive in the same way. Utilizing the 0.620.90 m region, we have achieved an rms precision of 10 ms-1 for an M5.5V spectral type star with spectral S/N 160 on 5-min time-scales. By M8V spectral type, a precision of 30 ms-1 at S/N = 25 is suggested, although more observations are needed. An assessment of our errors and scatter in the radial velocity points hints at the presence of stellar radial velocity variations. Of our sample of seven stars, two show radial velocity signals at 6s and 10s of the cross-correlation uncertainties. We find that chromospheric activity (via Ha variation) does not have an impact on our measurements and are unable to determine a relationship between the derived photospheric line profile morphology and radial velocity variations without further observations. If the signals are planetary in origin, our findings are consistent with estimates of Neptune mass planets that predict a frequency of 1327 per cent for early M dwarfs. Our current analysis indicates the we can achieve a sensitivity that is equivalent to the amplitude induced by a 6 M? planet orbiting in the habitable zone. Based on simulations, we estimate that <10 M? habitable zone planets will be detected in a new stellar mass regime, with =20 epochs of observations. Higher resolution and greater instrument stability indicate that photon-limited precisions of 2 ms-1 are attainable on moderately rotating M dwarfs (with vsin i= 5 km s-1) using our technique
ISC/OSI Journal Authors Survey Report
No full textOn behalf of the Joint Information Systems Committee (JISC) and the Open Society Institute (OSI) a survey of journal authors has been carried out by Key Perspectives Ltd. The terms of reference were to poll a cohort of authors who had published on an open access basis and another cohort of authors who had published their work in conventional journals without making the article available on open access. The survey’s aims were to investigate the authors’ awareness of new open access possibilities, the ease of identification of and submission to open access outlets, their experiences of publishing their work in this way, their concerns about any implications open access publishing may have upon their careers, and the reasons why (or not) they chose to publish through an open access outlet
Bibliographics for the 983 eprints in the live archives of E-LIS : trends and status report up to 7th July 2004, based on author-self-archiving metadata
No full textThe priority for ideas and philosophy related to "Network Theory" have been traced back and documented by Braun(2004),and credit goes to Karinthy(1929).The IT has empowered to realise it, as the most practical phenomena and it is no more a humour. The OAI (Open Archives Initiatives)and ACIS (Academic Contributor Information System)are progressive in the direction ,which may lead to realise the "Collective Genius" at global level. Focus of present study is on Author-Self-Archiving (A-S-A)Metadata of the 983 Eprints in the Live Archives of the E-LIS (EPrints of Library and Information Science),which were approved till 7th July 2004.The A-S-A Metadata was used for librametric analysis. Self-explanatory bibliographics are illustrated.The highlights include: Conference papers (34%); highest approval, June 2004 (28%); published archives (76%);not refereed (52%); not in public domain (60%); highest self-archiving-author (De Robbio, Antonella).The Nos. of EPrints having single JITA domain specifications were: Theoretical and general aspects of libraries and information(27); Information use and sociology of information(80);Users,literacy and reading(13);Libraries as physical collections(30);Publishing and legal issues(57);Management(13);Industry, profession and education(36);Information sources, supports, channels(113) ; Information treatment for information services, Information functions and techniques (101); Technical services libraries, archives and museums(25); Housing technologies(1); Information technology and library technology(92); and Inter-domainery (395) i.e. having specifications of two or more than two JITA classes
Is it possible to detect planets around young active G and K dwarfs?
No full textTheoretical predictions suggest that the distribution of planets in very young stars could be very different to that typically observed in Gyr old systems that are the current focus of radial velocity surveys. However, the detection of planets around young stars is hampered by the increased stellar activity associated with young stars, the signatures of which can bias the detection of planets. In this paper, we place realistic limitations on the possibilities for detecting planets around young active G and K dwarfs. The models of stellar activity based on tomographic imaging of the G dwarf HD 141943 and the K1 dwarf AB Dor also include contributions from plage and many small random starspots. Our results show that the increased stellar activity levels present on young solar-type stars strongly impacts the detection of Earth-mass and Jupiter-mass planets and that the degree of activity jitter is directly correlated with stellar v sin i. We also show that for G and K dwarfs, the distribution of activity in individual stars is more important than the differences in induced radial velocities as a function of spectral type. We conclude that Jupiter-mass planets can be detected close-in around fast-rotating young active stars, Neptune-mass planets around moderate rotators and that Super-Earths are only detectable around very slowly rotating stars. The effects of an increase in stellar activity jitter by observing younger stars can be compensated for by extending the observational base-line to at least 100 epochs
The discovery of an M4+T8.5 binary system
No full textWe report the discovery of a T8.5 dwarf, which is a companion to the M4 dwarf Wolf 940. At a distance of 12.50(+0.75)(-0.67)pc, the angular separation of 32 arcsec corresponds to a projected separation of 400 au. The M4 primary displays no Ha emission, and we apply the age-activity relations of West et al. to place a lower limit on the age of the system of 3.5 Gyr. Weak Ha absorption suggests some residual activity, and we estimate an upper age limit of 6 Gyr. We apply the relations of Bonfils et al. for V-K(s) and M(Ks) to determine the metallicity, [Fe/H] = -0.06 +/- 0.20 for Wolf 940A, and by extension the T8.5 secondary, Wolf 940B. We have obtained JHK NIRI spectroscopy and JHKL' photometry of Wolf 940B, and use these data, in combination with theoretical extensions, to determine its bolometric flux, F(bol) = 1.75 +/- 0.18 x 10(-16) Wm(-2), and thus its luminosity log (L( )/L(circle dot)) =-6.07 +/- 0.04. Using the age constraints for the system and evolutionary structural models of Baraffe et al., we determine T(eff) = 570 +/- 25K and log g = 4.75-5.00 for Wolf 940B, based on its bolometric luminosity. This represents the first determination of these properties for a T8+ dwarf that does not rely on the fitting of T dwarf spectral models. This object represents the first system containing a T8+ dwarf for which fiducial constraints on its properties are available, and we compare its spectra with those of the latest very cool BT-Settl models. This clearly demonstrates that the use of the (W(J), K/J) spectral ratios (used previously to constrain T(eff) and log g) would have overestimated T(eff) by similar to 100 K.NSF [AST-0507833]; Alfred P. Sloan Research Fellowshi
The discovery of the T8.5 dwarf UGPS J0521+3640
No full textWe have carried out a search for late-type T dwarfs in the UKIRT Infrared Deep Sky Survey Galactic Plane Survey 6th Data Release. The search yielded two persuasive candidates, both of which have been confirmed as T dwarfs. The brightest, UGPS J0521+3640, has been assigned the spectral type T8.5 and appears to lie at a distance of 7-9 pc. The fainter of the two, UGPS J0652+0324, is classified as a T5.5 dwarf and lies at an estimated distance of 28-37 pc. Warm-Spitzer observations in IRAC channels 1 and 2, taken as part of the GLIMPSE360 Legacy Survey, are available for UGPS J0521+3640 and we used these data with the near-infrared spectroscopy to estimate its properties. We find best-fitting solar metallicity BT-Settl models for T-eff = 600 and 650 K and log g = 4.5 and 5.0. These parameters suggest a mass between 14 and 32M(J) for an age between 1 and 5 Gyr. The proximity of this very cool T dwarf, and its location in the Galactic plane, makes it an ideal candidate for high-resolution adaptive optics imaging to search for cool companions
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