23 research outputs found

    A trio of gamma-ray burst supernovae: GRB 120729A, GRB 130215A/SN 2013ez, and GRB 130831A/SN 2013fu

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    We present optical and near-infrared (NIR) photometry for three gamma-ray burst supernovae (GRB-SNe): GRB 120729A, GRB 130215A/SN 2013ez, and GRB 130831A/SN 2013fu. For GRB 130215A/SN 2013ez, we also present optical spectroscopy at t − t0 = 16.1 d, which covers rest-frame 3000–6250 Å. Based on Fe ii λ5169 and Si ii λ6355, our spectrum indicates an unusually low expansion velocity of ~4000–6350 km s-1, the lowest ever measured for a GRB-SN. Additionally, we determined the brightness and shape of each accompanying SN relative to a template supernova (SN 1998bw), which were used to estimate the amount of nickel produced via nucleosynthesis during each explosion. We find that our derived nickel masses are typical of other GRB-SNe, and greater than those of SNe Ibc that are not associated with GRBs. For GRB 130831A/SN 2013fu, we used our well-sampled R-band light curve (LC) to estimate the amount of ejecta mass and the kinetic energy of the SN, finding that these too are similar to other GRB-SNe. For GRB 130215A, we took advantage of contemporaneous optical/NIR observations to construct an optical/NIR bolometric LC of the afterglow. We fit the bolometric LC with the millisecond magnetar model of Zhang & Mészáros (2001, ApJ, 552, L35), which considers dipole radiation as a source of energy injection to the forward shock powering the optical/NIR afterglow. Using this model we derive an initial spin period of P = 12 ms and a magnetic field of B = 1.1 × 1015 G, which are commensurate with those found for proposed magnetar central engines of other long-duration GRBs

    Long optical plateau in the afterglow of the short GRB 150424A with extended emission

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    Context. Short-duration gamma-ray bursts (GRBs) with extended emission form a subclass of short GRBs, comprising about 15% of the short-duration sample. Afterglow detections of short GRBs are also rare (about 30%) because of their lower luminosity. Aims. We present a multiband data set of the short burst with extended emission, GRB 150424A, comprising of GROND observations, complemented with data from Swift/UVOT, Swift/XRT, HST, Keck/LRIS, and data points from the literature. The GRB 150424A afterglow shows an extended plateau phase, lasting about 8 h. The analysis of this unique GRB afterglow might shed light on the understanding of afterglow plateau emission, the nature of which is still under debate. Methods. We present a phenomenological analysis made by applying fireball closure relations and interpret the findings in the context of the fireball model. We discuss the plausibility of a magnetar as a central engine, which would be responsible for additional and prolonged energy injection into the fireball. Results. We find convincing evidence for energy injection into the afterglow of GRB 150424A. We find that a magnetar spin-down as the source for a prolonged energy injection requires that at least 4% of the spin-down energy is converted into radiation

    The warm, the excited, and the molecular gas: GRB 121024A shining through its star-forming galaxy★

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    We present the first reported case of the simultaneous metallicity determination of a gamma-ray burst (GRB) host galaxy, from both afterglow absorption lines as well as strong emission-line diagnostics. Using spectroscopic and imaging observations of the afterglow and host of the long-duratio

    Diagnostic accuracy of a clinical diagnosis of idiopathic pulmonary fibrosis: An international case-cohort study

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    We conducted an international study of idiopathic pulmonary fibrosis (IPF) diagnosis among a large group of physicians and compared their diagnostic performance to a panel of IPF experts. A total of 1141 respiratory physicians and 34 IPF experts participated. Participants evaluated 60 cases of interstitial lung disease (ILD) without interdisciplinary consultation. Diagnostic agreement was measured using the weighted kappa coefficient (\u3baw). Prognostic discrimination between IPF and other ILDs was used to validate diagnostic accuracy for first-choice diagnoses of IPF and were compared using the Cindex. A total of 404 physicians completed the study. Agreement for IPF diagnosis was higher among expert physicians (\u3baw=0.65, IQR 0.53-0.72, p20 years of experience (C-index=0.72, IQR 0.0-0.73, p=0.229) and non-university hospital physicians with more than 20 years of experience, attending weekly MDT meetings (C-index=0.72, IQR 0.70-0.72, p=0.052), did not differ significantly (p=0.229 and p=0.052 respectively) from the expert panel (C-index=0.74 IQR 0.72-0.75). Experienced respiratory physicians at university-based institutions diagnose IPF with similar prognostic accuracy to IPF experts. Regular MDT meeting attendance improves the prognostic accuracy of experienced non-university practitioners to levels achieved by IPF experts

    Multi-messenger observations of a binary neutron star merger

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    On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

    La mediastinoscopia para el diagnóstico de la enfermedad mediastínica: análisis de 181 exploraciones

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    Para validar nuestra experiencia con la utilización de la mediastinoscopia cervical estándar (MCS) y la mediastinoscopia cervical extendida (MCE) en el diagnóstico de las adenopatías y masas del mediastino, se ha realizado este estudio entre enero de 1992 y febrero de 2001 sobre 181 pacientes. La MCS y MCE se han indicado para la estadificación ganglionar por carcinoma broncogénico (grupo I) y en el diagnóstico de las masas mediastínicas (grupo II). En todos los casos se ha efectuado una MCS para explorar la región paratraqueal (2R, 2L, 4R, 4L, 7, 10R, 10L) y en 32, además, una MCE para la ventana aortopulmonar o región subaórtica (área 5) y región paraaórtica (área 6). En el grupo I, la MCS ha demostrado una sensibilidad (S) del 93,6%, especificidad (E) del 100%, un valor predictivo positivo (VPP) del 100%, un valor predictivo negativo (VPN) del 82,8% y una rentabilidad diagnóstica (RD) del 95,1%. La MCE ha tenido una S del 91%, E del 100%, VPP del 100%, VPN del 93,3% y una RD del 96%. Para el grupo II, la MCS ha presentado una S del 93,3%, E 100%, VPP 100%, VPN 81,2% y una RD del 94,8% mientras que la MCE en este grupo ha tenido una S del 80%, E del 100%, VPP 100%, VPN 66,7% y una RD del 85,7%. El porcentaje de complicaciones ha sido del 2,7%, destacando un sangrado por lesión de la vena cava superior, una laceración traqueal, una parálisis recurrencial y 2 casos de infección de la herida quirúrgica. La estancia media postoperatoria ha sido de 36 h y la mortalidad nula. Concluimos que la MCS es una técnica de gran especificidad en la valoración de la afección ganglionar mediastínica por carcinoma broncogénico y la prueba de elección ante la imposibilidad o ausencia de diagnóstico en las lesiones localizadas en el mediastino medio. La MCE es una alternativa válida y segura a la mediastinotomía anterior en la valoración de las adenopatías y masas que ocupan las regiones paraaórtica y ventana aortopulmonar, presentando una elevada rentabilidad diagnóstica, una baja morbilidad y una nula mortalidad

    Mejoras en la preservación pulmonar: tres años de experiencia con una solución de dextrano bajo en potasio

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    Objetivo: La calidad de la preservación pulmonar es uno de los aspectos más determinantes en el éxito del trasplante pulmonar. En octubre del año 2000 modificamos nuestra solución de preservación pulmonar, que hasta entonces era el Euro-Collins (EC), y comenzamos a utilizar una solución de dextrano bajo en potasio, comercializada como Perfadex (PER). El objetivo de este estudio es analizar los resultados de ambos métodos. Material y métodos: Hemos analizado los resultados de 68 trasplantes pulmonares con PER y los hemos comparado con los de una serie retrospectiva del mismo número de trasplantes realizados con EC. Resultados: No existen diferencias significativas respecto a la edad o el diagnóstico de los receptores entre ambos grupos. El tiempo en lista de espera fue mayor en el grupo de PER. La causa de muerte del donante más frecuente del grupo EC fue el traumatismo craneoencefálico (62%), mientras que en el grupo de PER fue la hemorragia cerebral (54%). En el grupo de PER se realizaron más trasplantes bipulmonares que en el de EC (el 78 y el 53%, respectivamente; p = 0,002). No hay diferencias en la indicación de circulación extracorpórea o tiempos de isquemia entre ambos grupos. Se evaluó la función pulmonar temprana a través del índice de oxigenación (PaO2/FiO2) a la llegada a la unidad de cuidados intensivos, que fue comparable entre ambos grupos. La incidencia de disfunción grave del injerto (PaO2/FiO2 < 150 mmHg) fue significativamente inferior en el grupo de PER frente al de EC (el 16 y el 37%, respectivamente; p = 0,01). No encontramos diferencias significativas respecto a las horas de ventilación mecánica ni en cuanto a la mortalidad postoperatoria entre las 2 series. Conclusiones: Con la aplicación clínica de esta nueva solución de preservación pulmonar se obtiene una reducción del 50% en la incidencia de la lesión de isquemia-reperfusión grave del injerto en el postoperatorio inmediato del trasplante pulmonar
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