82 research outputs found

    La erupción submarina de La Restinga en la isla de El Hierro, Canarias: Octubre 2011-Marzo 2012

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    The first signs of renewed volcanic activity at El Hierro began in July 2011 with the occurrence of abundant, low-magnitude earthquakes. The increasing seismicity culminated on October 10, 2011, with the onset of a submarine eruption about 2 km offshore from La Restinga, the southernmost village on El Hierro. The analysis of seismic and deformation records prior to, and throughout, the eruption allowed the reconstruction of its main phases: 1) ascent of magma and migration of hypocentres from beneath the northern coast (El Golfo) towards the south rift zone, close to La Restinga, probably marking the hydraulic fracturing and the opening of the eruptive conduit; and 2) onset and development of a volcanic eruption indicated by sustained and prolonged harmonic tremor whose intensity varied with time. The features monitored during the eruption include location, depth and morphological evolution of the eruptive source and emission of floating volcanic bombs. These bombs initially showed white, vesiculated cores (originated by partial melting of underlying pre-volcanic sediments upon which the island of El Hierro was constructed) and black basanite rims, and later exclusively hollow basanitic lava balloons. The eruptive products have been matched with a fissural submarine eruption without ever having attained surtseyan explosiveness. The eruption has been active for about five months and ended in March 2012, thus becoming the second longest reported historical eruption in the Canary Islands after the Timanfaya eruption in Lanzarote (1730-1736). This eruption provided the first opportunity in 40 years to manage a volcanic crisis in the Canary Islands and to assess the interpretations and decisions taken, thereby gaining experience for improved management of future volcanic activity. Seismicity and deformation during the eruption were recorded and analysed by the Instituto Geográfico Nacional (IGN). Unfortunately, a lack of systematic sampling of erupted pyroclasts and lavas, as well as the sporadic monitoring of the depth and growth of the submarine vent by deployment of a research vessel, hampered a comprehensive assessment of hazards posed during volcanic activity. Thus, available scientific data and advice were not as high quality as they could have been, thereby limiting the authorities in making the proper decisions at crucial points during the crisis. The response in 2011-12 to the El Hierro eruption has demonstrated that adequate infrastructure and technical means exist in the Canary Islands for the early detection of potential eruptive hazards. However, it also has taught us that having detailed emergency management plans may be of limited value without an accompanying continuous, well-integrated scientific monitoring effort (open to national and international collaboration) during all stages of an eruption.Los primeros indicios de una posible erupción volcánica en El Hierro se percibieron a partir de julio de 2011 en forma de sismos de baja intensidad pero anormalmente numerosos. La intensificación de la sismicidad culminó con el inicio de la erupción submarina el 10 de octubre de 2011 a unos 2 km al sur de La Restinga. La sismicidad y deformación del terreno que precedieron y acompañaron a esta erupción han permitido reconstruir las principales fases de actividad volcánica: 1) generación y ascenso del magma con migración de los hipocentros sísmicos desde el norte, en el Golfo, hasta el rift sur, en La Restinga, marcando la apertura hidráulica del conducto magmático; y 2) inicio y continuidad de la erupción volcánica evidenciada por un tremor armónico continuo de intensidad variable en el tiempo. Las características observadas a lo largo de la erupción, principalmente localización, profundidad y evolución morfológica del foco emisor, así como emisión de materiales volcánicos flotantes, inicialmente con un núcleo blanco poroso (procedentes de la fusión parcial de sedimentos de la capa superior de la corteza oceánica anteriores a la construcción del edificio insular de El Hierro) envuelto por una corteza basanítica y después huecas (lava balloons), se han correspondido con una erupción submarina fisural profunda sin que nunca hayan intervenido mecanismos más explosivos tipo surtseyano. La erupción se mantuvo activa durante unos cinco meses, dándose por finalizada en marzo del 2012, convirtiéndose de este modo en la segunda erupción histórica más longeva de Canarias después de la de Timanfaya (1730-36) en Lanzarote. Esta erupción ha supuesto la primera oportunidad en 40 años de gestionar una crisis volcánica en Canarias y de analizar las observaciones e interpretaciones y las decisiones adoptadas, con objeto de mejorar la gestión de futuras crisis volcánicas. El Instituto Geográfico Nacional (IGN) se encargó de adquirir y analizar la información sísmica y de deformación durante todo el proceso. Sin embargo, no se dispuso inicialmente de un barco oceanográfico que realizara estudios sistemáticos de la profundidad y progresión de la erupción, así como de toma de muestras de los materiales emitidos (piroclastos y lavas), elementos claves para la determinación de la peligrosidad eruptiva. Estas deficiencias en el seguimiento científico del proceso eruptivo dificultaron en algunos momentos la toma de decisiones de protección civil. El análisis de la crisis ha puesto de manifiesto que, aunque se disponga de una infraestructura técnica adecuada para la detección temprana de crisis eruptivas en el archipiélago, de poco valen las medidas administrativas planificadas sin un seguimiento científico continuo e integrador del proceso eruptivo, abierto a la colaboración científica nacional e internacional

    La gran erupción de hace 4.2 ka cal en Cerro Blanco, Zona Volcánica Central, Andes: nuevos datos sobre los depósitos eruptivos holocenos en la Puna sur y regiones adyacentes

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    The eruption of the Cerro Blanco Volcanic Complex, in the southern Puna, NW Argentina dated at 4410–4150 a cal BP, was investigated to produce new information on stratigraphy, geomorphology, physical volcanology, radiocarbon dating, petrography, and geochemistry. Identification of pre–, syn–, and post–caldera products allowed us to estimate the distribution of the Plinian fallout during the paroxysmal syn–caldera phase of the eruption. The new results provide evidence for a major rhyolitic explosive eruption that spread volcanic deposits over an area of ~500,000 km2, accumulating > 100 km3 of tephra (bulk volume). This last value exceeds the lower threshold of Volcanic Explosive Index (VEI) of 7. Ash-fall deposits mantled the region at distances > 400 km from source and thick pyroclastic-flow deposits filled neighbouring valleys up to 35 km away. This eruption is the largest documented during the past five millennia in the Central Volcanic Zone of the Andes, and is probably one of the largest Holocene explosive eruptions in the world. We have also identified two additional rhyolitic eruptions in the region from two other eruptive sources: one during the Early–Holocene and another in the Late–Holocene. The identification and characterisation of these significant volcanic events provide new constraints into regional Holocene geological and archaeological records, and offer extensive regional chronostratigraphic markers over a wide geographical area of South America.La erupción del Complejo Volcánico Cerro Blanco en el sur de la Puna, noroeste de Argentina (4410–4150 a BP) se investigó para obtener nueva información sobre estratigrafía, geomorfología, volcanología física, dataciones por radiocarbono, petrografía y geoquímica. La caracterización de los productos en relación a la evolución de la caldera de Cerro Blanco permitió estimar la distribución de los depósitos de ceniza de la fase paroxísmica Plineana de la erupción. Estos novedosos resultados evidencian una gran erupción explosiva riolítica que generó depósitos cineríticos en un área de aproximadamente 500.000 km2, acumulando > 100 km3 de tefra (volumen total). Este último valor supera el umbral inferior del Índice de Explosividad Volcánica (IEV) de 7. Los depósitos de caída de ceniza cubrieron la región, llegando a más de 400 km desde el Complejo Volcánico de Cerro Blanco, y los potentes depósitos de flujos piroclásticos rellenaron los valles vecinos alcanzando una distancia de 35 km. Esta erupción es la más grande documentada durante los últimos cinco milenios en la Zona Volcánica Central de los Andes y es probablemente una de las mayores erupciones explosivas holocenas del mundo. Además, se han identificado otras dos erupciones riolíticas en la región procedentes de otros dos centros eruptivos: una durante el Holoceno temprano y otra en el Holoceno tardío. La identificación y caracterización de estos grandes eventos volcánicos proporcionan nuevas guías para los registros geológicos y arqueológicos regionales del Holoceno, siendo marcadores cronostratigráficos de aplicación a una extensa área geográfica de América del Sur

    Identification and Characterization of Peripheral T-Cell Lymphoma-Associated SEREX Antigens

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    Peripheral T-cell lymphomas (PTCL) are generally less common and pursue a more aggressive clinical course than B-cell lymphomas, with the T-cell phenotype itself being a poor prognostic factor in adult non-Hodgkin lymphoma (NHL). With notable exceptions such as ALK+ anaplastic large cell lymphoma (ALCL, ALK+), the molecular abnormalities in PTCL remain poorly characterised. We had previously identified circulating antibodies to ALK in patients with ALCL, ALK+. Thus, as a strategy to identify potential antigens associated with the pathogenesis of PTCL, not otherwise specified (PTCL, NOS), we screened a testis cDNA library with sera from four PTCL, NOS patients using the SEREX (serological analysis of recombinant cDNA expression libraries) technique. We identified nine PTCL, NOS-associated antigens whose immunological reactivity was further investigated using sera from 52 B- and T-cell lymphoma patients and 17 normal controls. The centrosomal protein CEP250 was specifically recognised by patients sera and showed increased protein expression in cell lines derived from T-cell versus B-cell malignancies. TCEB3, BECN1, and two previously uncharacterised proteins, c14orf93 and ZBTB44, were preferentially recognised by patients' sera. Transcripts for all nine genes were identified in 39 cancer cell lines and the five genes encoding preferentially lymphoma-recognised antigens were widely expressed in normal tissues and mononuclear cell subsets. In summary, this study identifies novel molecules that are immunologically recognised in vivo by patients with PTCL, NOS. Future studies are needed to determine whether these tumor antigens play a role in the pathogenesis of PTCL

    EPIdemiology of Surgery-Associated Acute Kidney Injury (EPIS-AKI) : Study protocol for a multicentre, observational trial

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    More than 300 million surgical procedures are performed each year. Acute kidney injury (AKI) is a common complication after major surgery and is associated with adverse short-term and long-term outcomes. However, there is a large variation in the incidence of reported AKI rates. The establishment of an accurate epidemiology of surgery-associated AKI is important for healthcare policy, quality initiatives, clinical trials, as well as for improving guidelines. The objective of the Epidemiology of Surgery-associated Acute Kidney Injury (EPIS-AKI) trial is to prospectively evaluate the epidemiology of AKI after major surgery using the latest Kidney Disease: Improving Global Outcomes (KDIGO) consensus definition of AKI. EPIS-AKI is an international prospective, observational, multicentre cohort study including 10 000 patients undergoing major surgery who are subsequently admitted to the ICU or a similar high dependency unit. The primary endpoint is the incidence of AKI within 72 hours after surgery according to the KDIGO criteria. Secondary endpoints include use of renal replacement therapy (RRT), mortality during ICU and hospital stay, length of ICU and hospital stay and major adverse kidney events (combined endpoint consisting of persistent renal dysfunction, RRT and mortality) at day 90. Further, we will evaluate preoperative and intraoperative risk factors affecting the incidence of postoperative AKI. In an add-on analysis, we will assess urinary biomarkers for early detection of AKI. EPIS-AKI has been approved by the leading Ethics Committee of the Medical Council North Rhine-Westphalia, of the Westphalian Wilhelms-University Münster and the corresponding Ethics Committee at each participating site. Results will be disseminated widely and published in peer-reviewed journals, presented at conferences and used to design further AKI-related trials. Trial registration number NCT04165369

    Evaluation of appendicitis risk prediction models in adults with suspected appendicitis

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    Background Appendicitis is the most common general surgical emergency worldwide, but its diagnosis remains challenging. The aim of this study was to determine whether existing risk prediction models can reliably identify patients presenting to hospital in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis. Methods A systematic search was completed to identify all existing appendicitis risk prediction models. Models were validated using UK data from an international prospective cohort study that captured consecutive patients aged 16–45 years presenting to hospital with acute RIF in March to June 2017. The main outcome was best achievable model specificity (proportion of patients who did not have appendicitis correctly classified as low risk) whilst maintaining a failure rate below 5 per cent (proportion of patients identified as low risk who actually had appendicitis). Results Some 5345 patients across 154 UK hospitals were identified, of which two‐thirds (3613 of 5345, 67·6 per cent) were women. Women were more than twice as likely to undergo surgery with removal of a histologically normal appendix (272 of 964, 28·2 per cent) than men (120 of 993, 12·1 per cent) (relative risk 2·33, 95 per cent c.i. 1·92 to 2·84; P < 0·001). Of 15 validated risk prediction models, the Adult Appendicitis Score performed best (cut‐off score 8 or less, specificity 63·1 per cent, failure rate 3·7 per cent). The Appendicitis Inflammatory Response Score performed best for men (cut‐off score 2 or less, specificity 24·7 per cent, failure rate 2·4 per cent). Conclusion Women in the UK had a disproportionate risk of admission without surgical intervention and had high rates of normal appendicectomy. Risk prediction models to support shared decision‐making by identifying adults in the UK at low risk of appendicitis were identified
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