Plausible fluorescent Ly-alpha emitters around the z=3.1 QSO0420-388

We report the results of a survey for fluorescent Ly-alpha emission carried out in the field surrounding the z=3.1 quasar QSO0420-388 using the FORS2 instrument on the VLT. We first review the properties expected for fluorescent Ly-alpha emitters, compared with those of other non-fluorescent Ly-alpha emitters. Our observational search detected 13 Ly-alpha sources sparsely sampling a volume of ~14000 comoving Mpc^3 around the quasar. The properties of these in terms of i) the line equivalent width, ii) the line profile and iii) the value of the surface brightness related to the distance from the quasar, all suggest that several of these may be plausibly fluorescent. Moreover, their number is in good agreement with the expectation from theoretical models. One of the best candidates for fluorescence is sufficiently far behind QSO0420-388 that it would imply that the quasar has been active for (at least) ~60 Myrs. Further studies on such objects will give information about proto-galactic clouds and on the radiative history (and beaming) of the high-redshift quasars.Comment: 10 pages, 4 figures.Update to match the version published on ApJ 657, 135, 2007 March

Tests of the Las Campanas Distant Cluster Survey from Confirmation Observations for the ESO Distant Cluster Survey

The ESO Distant Cluster Survey (EDisCS) is a photometric and spectroscopic study of the galaxy cluster population at two epochs, z~0.5 and z~0.8, drawn from the Las Campanas Distant Cluster Survey (LCDCS). We report results from the initial candidate confirmation stage of the program and use these results to probe the properties of the LCDCS. Of the 30 candidates targeted, we find statistically significant overdensities of red galaxies near 28. Of the ten additional candidates serendipitously observed within the fields of the targeted 30, we detect red galaxy overdensities near six. We test the robustness of the published LCDCS estimated redshifts to misidentification of the brighest cluster galaxy (BCG) in the survey data, and measure the spatial alignment of the published cluster coordinates, the peak red galaxy overdensity, and the brightest cluster galaxy. We conclude that for LCDCS clusters out to z~0.8, 1) the LCDCS coordinates agree with the centroid of the red galaxy overdensity to within 25'' (~150 h^{-1} kpc) for 34 out of 37 candidates with 3\sigma galaxy overdensities, 2) BCGs are typically coincident with the centroid of the red galaxy population to within a projected separation of 200 h^{-1} kpc (32 out of 34 confirmed candidates), 3) the red galaxy population is strongly concentrated, and 4) the misidentification of the BCG in the LCDCS causes a redshift error >0.1 in 15-20% of the LCDCS candidates. These findings together help explain the success of the surface brightness fluctuations detection method.Comment: 10 pages, 9 figures, accepted for publication in the November 10 issue of Ap

Fluorescent Ly-alpha emission from the high-redshift intergalactic medium

We combine a high-resolution hydro-simulation of the LambdaCDM cosmology with two radiative transfer schemes (for continuum and line radiation) to predict the properties, spectra and spatial distribution of fluorescent Ly-alpha emission at z~3. We focus on line radiation produced by recombinations in the dense intergalactic medium ionized by UV photons. In particular, we consider both a uniform background and the case where gas clouds are illuminated by a nearby quasar. We find that the emission from optically thick regions is substantially less than predicted from the widely used static, plane-parallel model. The effects induced by a realistic velocity field and by the complex geometric structure of the emitting regions are discussed in detail. We make predictions for the expected brightness and size distributions of the fluorescent sources.Our results account for recent null detections and can be used to plan new observational campaigns both in the field (to measure the intensity of the diffuse UV background) and in the proximity of bright quasars (to understand the origin of high colum-density absorbers).Comment: 15 pages, 12 figures, accepted for publication in Ap

Statistical evaluation of SCADA data for wind turbine condition monitoring and farm assessment

Operational data from wind farms is crucial for wind turbine condition monitoring and performance assessment. In this paper, we analyse three wind farms with the aim to monitor environmental and operational conditions that might result in underperformance or failures. The assessment includes a simple wind speed characterisation and wake analysis. The evolution of statistical parameters is used to identify anomalous turbine behaviour. In total, 88 turbines and 12 failures are analysed, covering different component failures. Notwithstanding the short period of data available, several operational parameters are found to deviate from the farm trend in some turbines affected by failures. As a result, some parameters show better monitoring capabilities than others, for the detection of certain failures. However, the limitations of SCADA statistics are also shown as not all failures showed anomalies in the observed parameters

The ideal trefoil knot

The most tight conformation of the trefoil knot found by the SONO algorithm is presented. Structure of the set of its self-contact points is analyzed.Comment: 11 pages, 8 figure

ProsocialLearn: D2.3 - 1st system requirements and architecture

This document present the first version of the ProsocialLearn architecture covering the principle definition, the requirement collection, the “business”, “information system”, “technology” architecture as defined in the TOGAF methodology

Nonvanishing Local Moment in Triplet Superconductors

The Kondo effect in a $p_x + {\rm i} p_y$-wave superconductor is studied by applying the Wilson's numerical renormalization group method. In this type of superconductor with a full energy gap like a s-wave one, the ground state is always a spin doublet, while a local spin is shrunk by the Kondo effect. The calculated magnetic susceptibility indicates that the spin of the ground state is generated by the orbital effect of the $p_x + {\rm i} p_y$-wave Cooper pairs. The effect of spin polarization of the triplet superconductor is also discussed.Comment: 5 pages, 4 figures, to be published in J. Phys. Soc. Jp

Annual changes in the Biodiversity Intactness Index in tropical and subtropical forest biomes, 2001–2012

Few biodiversity indicators are available that reflect the state of broad-sense biodiversity—rather than of particular taxa—at fine spatial and temporal resolution. One such indicator, the Biodiversity Intactness Index (BII), estimates how the average abundance of the native terrestrial species in a region compares with their abundances in the absence of pronounced human impacts. We produced annual maps of modelled BII at 30-arc-second resolution (roughly 1 km at the equator) across tropical and subtropical forested biomes, by combining annual data on land use, human population density and road networks, and statistical models of how these variables affect overall abundance and compositional similarity of plants, fungi, invertebrates and vertebrates. Across tropical and subtropical biomes, BII fell by an average of 1.9 percentage points between 2001 and 2012, with 81 countries seeing an average reduction and 43 an average increase; the extent of primary forest fell by 3.9% over the same period. We did not find strong relationships between changes in BII and countries’ rates of economic growth over the same period; however, limitations in mapping BII in plantation forests may hinder our ability to identify these relationships. This is the first time temporal change in BII has been estimated across such a large region