3,544 research outputs found

    Football intermediaries and self‑regulation: the need for greater transparency through disciplinary law, sanctioning and qualifying criteria

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    This paper was first presented at the International Sports Law Conference in The Hague in October 2018. It summarises the author’s work and wider research on the introduction of new proposals for the regulation of football intermediaries (a term which the author finds unworkable and unorthodox). The author’s research critically analyses the current regulatory framework and identifies the elements that form the basis for the inadequacy and ineffectiveness of the regulations currently in force. With the use of case studies and examples drawn from the author’s private practice, recommendations are produced for new regulations that would promote transparency, equality and consistency. The author concludes that this can only be achieved via a blending of self-regulation and external regulation at an international setting

    The Lennard-Jones-Devonshire cell model revisited

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    We reanalyse the cell theory of Lennard-Jones and Devonshire and find that in addition to the critical point originally reported for the 12-6 potential (and widely quoted in standard textbooks), the model exhibits a further critical point. We show that the latter is actually a more appropriate candidate for liquid-gas criticality than the original critical point.Comment: 5 pages, 3 figures, submitted to Mol. Phy

    A Rest-frame Optical View on z~4 Galaxies I: Color and Age Distributions from Deep IRAC Photometry of the IUDF10 and GOODS Surveys

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    We present a study of rest-frame UV-to-optical color distributions for z~4 galaxies based on the combination of deep HST/ACS+WFC3/IR data with Spitzer/IRAC imaging. In particular, we use new, ultra-deep data from the IRAC Ultradeep Field program (IUDF10). Our sample contains a total of ~2600 galaxies selected as B-dropout Lyman Break Galaxies (LBGs) in the HUDF and one of its deep parallel fields, the HUDF09-2, as well as GOODS-North and South. This sample is used to investigate the UV continuum slopes beta and Balmer break colors (J_125-[4.5]) as a function of rest-frame optical luminosity. The [4.5] filter is chosen to avoid potential contamination by strong rest-frame optical emission lines. We find that galaxies at M_z<-21.5 (roughly corresponding to L*[z~4]) are significantly redder than their lower luminosity counterparts. The UV continuum slopes and the J_125-[4.5] colors are well correlated. The most simple explanation for this correlation is that the dust reddening at these redshifts is better described by an SMC-like extinction curve, rather than the typically assumed Calzetti reddening. After correcting for dust, we find that the galaxy population shows mean stellar population ages in the range 10^8.5 to 10^9 yr, with a dispersion of ~0.5 dex, and only weak trends as a function of luminosity. In contrast to some results from the literature, we find that only a small fraction of galaxies shows Balmer break colors which are consistent with extremely young ages, younger than 100 Myr. Under the assumption of smooth star-formation histories, this fraction is only 12-19% for galaxies at M_z<-19.75. Our results are consistent with a gradual build-up of stars and dust in galaxies at z>4, with only a small fraction of stars being formed in short, intense bursts of star-formation.Comment: 11 pages, 10 figures; submitted to Ap

    A Spectroscopic Redshift Measurement for a Luminous Lyman Break Galaxy at z=7.730 using Keck/MOSFIRE

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    We present a spectroscopic redshift measurement of a very bright Lyman break galaxy at z=7.7302+-0.0006 using Keck/MOSFIRE. The source was pre-selected photometrically in the EGS field as a robust z~8 candidate with H=25.0 mag based on optical non-detections and a very red Spitzer/IRAC [3.6]-[4.5] broad-band color driven by high equivalent width [OIII]+Hbeta line emission. The Lyalpha line is reliably detected at 6.1 sigma and shows an asymmetric profile as expected for a galaxy embedded in a relatively neutral inter-galactic medium near the Planck peak of cosmic reionization. The line has a rest-frame equivalent width of EW0=21+-4 A and is extended with V_FWHM=360+90-70 km/s. The source is perhaps the brightest and most massive z~8 Lyman break galaxy in the full CANDELS and BoRG/HIPPIES surveys, having assembled already 10^(9.9+-0.2) M_sol of stars at only 650 Myr after the Big Bang. The spectroscopic redshift measurement sets a new redshift record for galaxies. This enables reliable constraints on the stellar mass, star-formation rate, formation epoch, as well as combined [OIII]+Hbeta line equivalent widths. The redshift confirms that the IRAC [4.5] photometry is very likely dominated by line emission with EW0(OIII+Hbeta)= 720-150+180 A. This detection thus adds to the evidence that extreme rest-frame optical emission lines are a ubiquitous feature of early galaxies promising very efficient spectroscopic follow-up in the future with infrared spectroscopy using JWST and, later, ELTs.Comment: 6 pages, 4 figures, small updates to match ApJL accepted versio

    UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields

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    The remarkable HST datasets from the CANDELS, HUDF09, HUDF12, ERS, and BoRG/HIPPIES programs have allowed us to map out the evolution of the UV LF from z~10 to z~4. We have identified 5859, 3001, 857, 481, 217, and 6 galaxy candidates at z~4, z~5, z~6, z~7, z~8, and z~10, respectively from the ~1000 arcmin**2 area probed. The selection of z~4-8 galaxies over the five CANDELS fields allows us to assess the cosmic variance; the largest variations are apparent at z>=7. Our new LF determinations at z~4 and z~5 span a 6-mag baseline (-22.5 to -16 AB mag). These determinations agree well with previous estimates, but the larger samples and volumes probed here result in a more reliable sampling of >L* galaxies and allow us to reassess the form of the UV LFs. Our new LF results strengthen our earlier findings to 3.4 sigma significance for a steeper faint-end slope to the UV LF at z>4, with alpha evolving from alpha=-1.64+/-0.04 at z~4 to alpha=-2.06+/-0.13 at z~7 (and alpha = -2.02+/-0.23 at z~8), consistent with that expected from the evolution of the halo mass function. With our improved constraints at the bright end, we find less evolution in the characteristic luminosity M* over the redshift range z~4 to z~7; the observed evolution in the LF is now largely represented by changes in phi*. No evidence for a non-Schechter-like form to the z~4-8 LFs is found. A simple conditional LF model based on halo growth and evolution in the M/L ratio of halos ((1+z)**-1.5) provides a good representation of the observed evolution.Comment: 53 pages, 28 figures, 11 tables, accepted for publication in the Astrophysical Journa

    Inductive learning spatial attention

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    This paper investigates the automatic induction of spatial attention from the visual observation of objects manipulated on a table top. In this work, space is represented in terms of a novel observer-object relative reference system, named Local Cardinal System, defined upon the local neighbourhood of objects on the table. We present results of applying the proposed methodology on five distinct scenarios involving the construction of spatial patterns of coloured blocks

    The Environment of M85 optical transient 2006-1: constraints on the progenitor age and mass

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    M85 optical transient 2006-1 (M85 OT 2006-1) is the most luminous member of the small family of V838 Mon-like objects, whose nature is still a mystery. This event took place in the Virgo cluster of galaxies and peaked at an absolute magnitude of I~-13. Here we present Hubble Space Telescope images of M85 OT 2006-1 and its environment, taken before and after the eruption, along with a spectrum of the host galaxy at the transient location. We find that the progenitor of M85 OT 2006-1 was not associated with any star forming region. The g and z-band absolute magnitudes of the progenitor were fainter than about -4 and -6 mag, respectively. Therefore, we can set a lower limit of ~50 Myr on the age of the youngest stars at the location of the progenitor that corresponds to a mass of <7 solar mass. Previously published line indices suggest that M85 has a mean stellar age of 1.6+/-0.3 Gyr. If this mean age is representative of the progenitor of M85 OT 2006-1, then we can further constrain its mass to be less than 2 solar mass. We compare the energetics and mass limit derived for the M85 OT 2006-1 progenitor with those expected from a simple model of violent stellar mergers. Combined with further modeling, these new clues may ultimately reveal the true nature of these puzzling events.Comment: 4 pages, accepted to Ap

    An Ontology of Soil Properties and Processes

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    Assessing the Underworld (ATU) is a large interdisciplinary UK research project, which addresses challenges in integrated inter-asset maintenance. As assets on the surface of the ground (e.g. roads or pave- ments) and those buried under it (e.g. pipes and cables) are supported by the ground, the properties and processes of soil a ect the performance of these assets to a signi cant degree. In order to make integrated deci- sions, it is necessary to combine the knowledge and expertise in multiple areas, such as roads, soil, buried assets, sensing, etc. This requires an underpinning knowledge model, in the form of an ontology. Within this context, we present a new ontology for describing soil properties (e.g. soil strength) and processes (e.g. soil compaction), as well as how they a ect each other. This ontology can be used to express how the ground a ects and is a ected by assets buried under the ground or on the ground surface. The ontology is written in OWL 2 and openly available from the University of Leeds data repository: http://doi.org/10.5518/54

    The Most Luminous z~9-10 Galaxy Candidates yet Found: The Luminosity Function, Cosmic Star-Formation Rate, and the First Mass Density Estimate at 500 Myr

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    [abridged] We present the discovery of four surprisingly bright (H_160 ~ 26 - 27 mag AB) galaxy candidates at z~9-10 in the complete HST CANDELS WFC3/IR GOODS-N imaging data, doubling the number of z~10 galaxy candidates that are known, just ~500 Myr after the Big Bang. Two similarly bright sources are also detected in a systematic re-analysis of the GOODS-S data set. Three of the four galaxies in GOODS-N are significantly detected at 4.5-6.2sigma in the very deep Spitzer/IRAC 4.5 micron data, as is one of the GOODS-S candidates. Furthermore, the brightest of our candidates (at z=10.2+-0.4) is robustly detected also at 3.6 micron (6.9sigma), revealing a flat UV spectral energy distribution with a slope beta=-2.0+-0.2, consistent with demonstrated trends with luminosity at high redshift. The abundance of such luminous candidates suggests that the luminosity function evolves more significantly in phi_* than in L_* at z>~8 with a higher number density of bright sources than previously expected. Despite the discovery of these luminous candidates, the cosmic star formation rate density for galaxies with SFR >0.7 M_sun/yr shows an order-of-magnitude increase in only 170 Myr from z ~ 10 to z ~ 8, consistent with previous results. Based on the IRAC detections, we derive galaxy stellar masses at z~10, finding that these luminous objects are typically 10^9 M_sun. The cosmic stellar mass density at z~10 is log10 rho_* = 4.7^+0.5_-0.8 M_sun Mpc^-3 for galaxies brighter than M_UV~-18. The remarkable brightness, and hence luminosity, of these z~9-10 candidates highlights the opportunity for deep spectroscopy to determine their redshift and nature, demonstrates the value of additional search fields covering a wider area to understand star-formation in the very early universe, and highlights the opportunities for JWST to map the buildup of galaxies at redshifts much earlier than z~10.Comment: 20 pages, 12 figures, changed to match resubmitted version to Ap
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