1,048 research outputs found

    The Nature of Faint Blue Stars in the PHL and Ton Catalogues based on Digital Sky Surveys

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    We determined accurate positions for 3000 of the "faint blue stars" in the PHL (Palomar-Haro-Luyten) and Ton/TonS catalogues. These were published from 1957 to 1962, and, aimed at finding new white dwarfs, provide approximate positions for about 10750 blue stellar objects. Some of these "stars" had become known as quasars, a type of objects unheard-of before 1963. We derived subarcsec positions from a comparison of published finding charts with images from the first-epoch Digitized Sky Survey. Numerous objects are now well known, but unfortunately neither their PHL or Ton numbers, nor their discoverers, are recognized in current databases. A comparison with modern radio, IR, UV and X-ray surveys leads us to suggest that the fraction of extragalactic objects in the PHL and Ton catalogues is at least 15 per cent. However, because we failed to locate the original PHL plates or finding charts, it may be impossible to correctly identify the remaining 7726 PHL objects.Comment: 3 pages, no figures, to appear in the proceedings of The Universe of Digital Sky Surveys, Naples, Italy, Nov 25-28, 2014; Astrophysics and Space Science, eds. N.R. Napolitano et a

    The Nature of the Secondary Star in the Black Hole X-Ray Transient V616 Mon (=A0620-00)

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    We have used NIRSPEC on Keck II to obtain KK-band spectroscopy of the low mass X-ray binary V616 Mon (= A0620-00). V616 Mon is the proto-typical soft x-ray transient containing a black hole primary. As such it is important to constrain the masses of the binary components. The modeling of the infrared observations of ellipsoidal variations in this system lead to a derived mass of 11.0 M_{\sun} for the black hole. The validity of this derivation has been called into question due to the possiblity that the secondary star's spectral energy distribution is contaminated by accretion disk emission (acting to dilute the variations). Our new KK-band spectrum of V616 Mon reveals a late-type K dwarf secondary star, but one that has very weak 12^{\rm 12}CO absorption features. Comparison of V616 Mon with SS Cyg leads us to estimate that the accretion disk supplies only a small amount of KK-band flux, and the ellipsoidal variations are not seriously contaminated. If true, the derived orbital inclination of V616 Mon is not greatly altered, and the mass of the black hole remains large. A preliminary stellar atmosphere model for the KK-band spectrum of V616 Mon reveals that the carbon abundance is approximately 50% of the solar value. We conclude that the secondary star in V616 Mon has either suffered serious contamination from the accretion of supernova ejecta that created the black hole primary, or it is the stripped remains of a formerly more massive secondary star, one in which the CNO cycle had been active.Comment: 20 pages, 5 figure

    Il Percorso Diagnostico Terapeutico Assistenziale del paziente con melanoma metastatico presso l\u2019Azienda Ospedaliera Universitaria Policlinico Paolo Giaccone di Palermo come strumento applicativo della clinical governance

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    L\u2019evoluzione dello scenario internazionale relativo alla sanit\ue0 identifica cinque specifiche dimensioni come driver del cambiamento: il sistema, la finanza, le persone, i processi e la tecnologia. In linea con tali elementi, il patto per la salute 2014-2016 esplicita la necessit\ue0 di una rivisitazione a tutti i livelli del sistema salute, sia organizzativo che gestionale, con l\u2019intento di aumentare l\u2019efficienza e l\u2019efficacia, sviluppando nuovi modelli assistenziali, anche nella logica delle reti cliniche, dove tra gli \u201cstrumenti\u201d viene identificata l\u2019attivazione di Percorsi Diagnostico Terapeutico Assistenziali (PDTA). I percorsi condivisi e codificati per i vari stadi di patologia, con un sistema di raccolta dei dati clinici che possa generare gli indicatori di processo e di esito, sono ritenuti indispensabili per innescare il miglioramento della qualit\ue0 e valutare l\u2019efficacia e l\u2019efficienza. Tenendo conto di queste premesse, nell\u2019ambito dell\u2019Azienda Ospedaliera Universitaria Policlinico Paolo Giaccone di Palermo \ue8 stata sviluppata una progettualit\ue0 al fine di formalizzare e studiare il PDTA del paziente con melanoma metastatico, identificando il percorso ideale e descrivendo il percorso applicabile con le relative leve del cambiamento. Il progetto ha reso evidente come la gestione consapevole del \u201cprofondo cambiamento\u201d in essere nelle organizzazioni clinico assistenziali pu\uf2 essere \u201cgovernata\u201d grazie anche alla \u201cdocumentazione\u201d del proprio modo di operare in riferimento alle Linee Guida di riferimento e alle relative raccomandazioni. Il progetto ha reso evidente inoltre come la sostenibilit\ue0 dei percorsi passa anche attraverso la definizione di opportuni indicatori, correlati alle diverse fasi ed attivit\ue0 chiave, da poter monitorare nella \u201cvita corrente dell\u2019organizzazione\u201d

    Social Impact of Renewable Energy Sources in the Province of Loja

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    In the future energy development of the planet, renewable energies are decisive, because of the benefits that these entail in their use, besides being inexhaustible; These are used in different ways, in heating in electrical energy, electrochemistry, among others. These energy sources in its implementation have had a social impact by generating jobs, improving the quality of life in remote areas, improving health by reducing pollution; In addition to the levels of knowledge reached not only by professionals but also the population in general. In Ecuador, during the last 10 years, in the introduction of renewable energies, fundamentally hydraulic projects have been worked on. Which four are already in operation, this is how the country has been consolidated, being one of the most energy-rich in the region, in the same way, this has generated sources of work for many people; besides avoiding large pollution to the atmosphere. In the province of Loja, a wind farm, photovoltaic power plants are deployed, and public lighting with photovoltaic systems is used in some sectors of the City. The objective of the work is to demonstrate the social impact that the introduction of these technologies has had in the province of Loja, not only in the social sphere but also cultural, economic, environmental and tourist

    Resonance line-profile calculations based on hydrodynamical models of cataclysmic variable winds

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    We present synthetic line profiles as predicted by the models of 2-D line- driven disk winds due to Proga, Stone & Drew. We compare the model line profiles with HST observations of the cataclysmic variable IX Vel. The model wind consists of a slow outflow that is bounded on the polar side by a fast stream. We find that these two components of the wind produce distinct spectral features. The fast stream produces profiles which show features consistent with observations. These include the appearance of the P-Cygni shape for a range of inclinations, the location of the maximum depth of the absorption component at velocities less than the terminal velocity, and the transition from absorption to emission with increasing inclination. However the model profiles have too little absorption or emission equivalent width. This quantitative difference between our models and observations is not a surprise because the line-driven wind models predict a mass loss rate that is lower than the rate required by the observations. We note that the model profiles exhibit a double-humped structure near the line center which is not echoed in observations. We identify this structure with a non-negligible redshifted absorption which is formed in the slow component of the wind where the rotational velocity dominates over expansion velocity. We conclude that the next generation of disk wind models, developed for application to CVs, needs to yield stronger wind driving out to larger disk radii than do the present models.Comment: LaTeX, 19 pages, to appear in Ap

    Perceived positive impact of cancer among long‐term survivors of childhood cancer: a report from the childhood cancer survivor study

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    Objective Investigations examining psychosocial adjustment among childhood cancer survivors have focused primarily on negative effects and psychopathology. Emergent literature suggests the existence of positive impact or adjustment experienced after cancer, as well. The purpose of this study is to examine the distribution of Perceived Positive Impact (PPI) and its correlates in young adult survivors of childhood cancer. Methods 6425 survivors and 360 siblings completed a comprehensive health survey, inclusive of a modified version of the Post‐traumatic Growth Inventory (PTGI) as a measure of PPI. Linear regression models were used to examine demographic, disease and treatment characteristics associated with PPI. Results Survivors were significantly more likely than siblings to report PPI. Endorsement of PPI was significantly greater among female and non‐white survivors, and among survivors exposed to at least one intense therapy, a second malignancy or cancer recurrence. Survivors diagnosed at older ages and fewer years since diagnosis were more likely to report PPI. Income, education and marital/relationship status appeared to have varied relationships to PPI depending upon the subscale being evaluated. Conclusions The existence and variability of PPI in survivors in this study suggest that individual characteristics, inclusive of race, gender, cancer type, intensity of treatment, age at diagnosis and time since diagnosis, have unique and specific associations with different aspects of perceived positive outcomes of childhood cancer. Copyright © 2011 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92025/1/pon1959.pd

    A medium deep Chandra and Subaru survey of the 13hr XMM/ROSAT deep survey area

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    We present the results of a Chandra ACIS-I survey of a high latitude region at 13h +38 which was earlier observed with ROSAT (McHardy et al. 1998) and which has recently been observed by XMM-Newton for 200ksec. XMM-Newton will provide good quality X-ray spectra for over 200 sources with fluxes around the knee of the logN/logS, which are responsible for the bulk of the X-ray background (XRB). The main aim of the Chandra observations is to provide arcsecond, or better, positions, and hence reliable identifications, for the XMM-Newton sources. The ACIS-I observations were arranged in a mosaic of four 30ksec pointings, covering almost all of the 15' radius XMM-Newton/ROSAT field. We detect 214 Chandra sources above 5 sigma significance, to a limiting flux of \~1.3e-15 erg/cm2/s (0.5-7 keV). Optical counterparts are derived from a Subaru SuprimeCam image reaching to R~27. The very large majority of the Chandra sources have an optical counterpart, with the distribution peaking at 23<R<24, although 14 have no counterpart to R=27. The fraction of X-ray sources with no identification brighter than R=27 is similar to that found in deeper Chandra surveys. The majority of the identifications are with galaxies. As found in other Chandra surveys, there is a very wide range of optical magnitude for given X-ray flux, implying a range of emission mechanisms, and many sources have high L_X/L_opt ratios, implying absorption at moderate redshift. Comparison with the earlier ROSAT survey shows that the accuracy of the ROSAT positions agrees very well with the predictions from simulations in McHardy et al. (1998) and that the large majority of the identifications were correct (abridged).Comment: 22 pages, MNRAS in press. A full resolution version is available at http://www.astro.soton.ac.uk/~kfg/catalogue.ps.g

    XMM-Newton 13H Deep field - I. X-ray sources

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    We present the results of a deep X-ray survey conducted with XMM-Newton, centred on the UK ROSAT 13H deep field area. This region covers 0.18 deg^2 and is the first of two areas covered with XMM-Newton as part of an extensive multi-wavelength survey designed to study the nature and evolution of the faint X-ray source population. We have produced detailed Monte-Carlo simulations to obtain a quantitative characterisation of the source detection procedure and to assess the reliability of the resultant sourcelist. We use the simulations to establish a likelihood threshold above which we expect less than 7 (3%) of our sources to be spurious. We present the final catalogue of 225 sources. Within the central 9 arcmin, 68 per cent of source positions are accurate to 2 arcsec, making optical follow-up relatively straightforward. We construct the N(>S) relation in four energy bands: 0.2-0.5 keV, 0.5-2 keV, 2-5 keV and 5-10 keV. In all but our highest energy band we find that the source counts can be represented by a double powerlaw with a bright end slope consistent with the Euclidean case and a break around 10^-14 cgs. Below this flux the counts exhibit a flattening. Our source counts reach densities of 700, 1300, 900 and 300 deg^-2 at fluxes of 4.1x10^-16, 4.5x10^-16, 1.1x10^-15 and 5.3x10^-15 cgs in the 0.2-0.5, 0.5-2, 2-5 and 5-10 keV energy bands respectively. We have compared our source counts with those in the two Chandra deep fields and Lockman hole and find our source counts to be amongst the highest of these fields in all energy bands. We resolve >51% (>50%) of the X-ray background emission in the 1-2 keV (2-5 keV) energy bands.Comment: 27 pages, 18 figures, MNRAS accepte

    On 4d rank-one N=3 superconformal field theories

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    We study the properties of 4d N=3 superconformal field theories whose rank is one, i.e. those that reduce to a single vector multiplet on their moduli space of vacua. We find that the moduli space can only be of the form C^3/Z_k for k=1,2,3,4,6, and that the supersymmetry automatically enhances to N=4 for k=1,2. In addition, we determine the central charges a and c in terms of k, and construct the associated 2d chiral algebras, which turn out to be exotic N=2 supersymmetric W-algebras.Comment: 24 page

    Lectures on F-theory compactifications and model building

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    These lecture notes are devoted to formal and phenomenological aspects of F-theory. We begin with a pedagogical introduction to the general concepts of F-theory, covering classic topics such as the connection to Type IIB orientifolds, the geometry of elliptic fibrations and the emergence of gauge groups, matter and Yukawa couplings. As a suitable framework for the construction of compact F-theory vacua we describe a special class of Weierstrass models called Tate models, whose local properties are captured by the spectral cover construction. Armed with this technology we proceed with a survey of F-theory GUT models, aiming at an overview of basic conceptual and phenomenological aspects, in particular in connection with GUT breaking via hypercharge flux.Comment: Invited contribution to the proceedings of the CERN Winter School on Supergravity, Strings and Gauge Theory 2010, to appear in Classical and Quantum Gravity; 63 pages; v2: references added, typos correcte
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