Fission fragment angular distribution measurements of U-235 and U-238 at CERN n_TOF facility

Neutron-induced fission cross sections of U-238 and U-235 are used as standards in the fast neutron region up to 200 MeV. A high accuracy of the standards is relevant to experimentally determine other neutron reaction cross sections. Therefore, the detection efficiency should be corrected by using the angular distribution of the fission fragments (FFAD), which are barely known above 20 MeV. In addition, the angular distribution of the fragments produced in the fission of highly excited and deformed nuclei is an important observable to investigate the nuclear fission process. In order to measure the FFAD of neutron-induced reactions, a fission detection setup based on parallel-plate avalanche counters (PPACs) has been developed and successfully used at the CERN-n_TOF facility. In this work, we present the preliminary results on the analysis of new U-235(n,f) and U-238(n,f) data in the extended energy range up to 200 MeV compared to the existing experimental data.Postprint (published version

Expresión geomorfológica de la actividad reciente de la falla de Amer (NE de la Península Ibérica)

Triangular facets, related drainage basins, alluvial fans and subtle scarps reveal the recent activity of the normal Amer fault (NE Spain). The 1427 earthquakes which reached epicentral intensities ranging between VI1 and VI11 have been attributed to the Amer fault. However, the geomorphologic and geologic characteristics of this fault (30 km length) suggest that it might be capable of producing larger earthquakes than those occurred during de 15th century

Paleoseismic results from multiple trenching analysis along a silent fault: The El Camp fault (Tarragona, northeastern Iberian Peninsula)

We present the paleoseismological analysis of the El Camp fault scarp. Paleoseismology constitutes the key methodology for any real estimate of seismic hazard in low-slip-rate areas with no reported historical earthquakes. The recent tectonic activity of this fault is evidenced by a young mountain front and a fault scarp which cuts Quatern a ry alluvial fans. A regional geological analysis indicates that three generations of alluvial fans are cut by the fault. Absolute (TL and U/Th) and relative datings show that the oldest fan is 300 ka old and the intermediate one is 125 ka old. The study of 7 trenches and the absolute datings performed (TL, U/Th, radiocarbon as well as pollen analysis) revealed the following: 1) the El Camp fault consists of two segments (the nort h e rn end of the southern segment is located close to Po rquerola creek); 2) only the southern segment has been active since 125 ka; 3) the fault is seismogenic because it is associated with liquefaction features and colluvial wedges; 4) the El Camp fault has produced at least three well constrained surface-rupturing earthquakes since 125 ka (events Z, Y, and X). Based on the different tectonic features observed in the trenches, the recurrence period of large earthquakes during this period was estimated to be around 30 ka and the elapsed time to be around 3000 yr. Using the fault length and the ve rtical displacement per event, the largest estimated earthquake had a magnitude of Mw 6.7.Se presenta el análisis paleosismológico de la falla de El Camp. La paleosismología es una herramienta imprescindible para la caracterización sísmica de fallas activas, lentas y sin sismicidad histórica y, por lo tanto, para cálculos de peligrosidad sísmica. La falla de El Camp muestra evidencias de actividad tectónica: un frente montañoso joven y un escarpe de falla que afecta a abanicos aluviales cuaternarios. Un análisis geológico regional, previo al paleosismológico, muestra tres generaciones de abanicos aluviales afectados por la falla. El techo de éstos ha sido datado (U/Th y TL en caliches) en 300 y 125 ka para las dos generaciones más antiguas. Del estudio de 7 trincheras y de las dataciones por U/Th, TL, radiocarbono y polen se han obtenido los siguientes resultados: 1) La falla tiene dos segmentos con límite en el barranco de la Po rquerola. Solamente el segmento al sur de este punto ha sido activo posteriormente a 125 ka. 2) La falla de El Camp es sismogénica. 3) Se han caracterizado un mínimo de tres eventos posteriores a 125 ka (eventos Z, Y, y X). 4) El período intersísmico reciente se ha estimado en 30 ka. 5) El tiempo transcurrido desde el último terremoto es de 3000 años. 6) La magnitud del terremoto máximo es MW 6. 7

Diagonalization of matrices over regular rings

Square matrices are shown to be diagonalizable over all known classes of (von Neumann) regular rings. This diagonalizability is equivalent to a cancellation property for finitely generated projective modules which conceivably holds over all regular rings. These results are proved in greater generality, namely for matrices and modules over exchange rings, where attention is restricted to regular matrices

Diagonalization of matrices over regular rings

Square matrices are shown to be diagonalizable over all known classes of (von Neumann) regular rings. This diagonalizability is equivalent to a cancellation property for finitely generated projective modules which conceivably holds over all regular rings. These results are proved in greater generality, namely for matrices and modules over exchange rings, where attention is restricted to regular matrices

Nuevas citas de Parasquilla ferussaci (Roux, 1830) (Crustacea, Stomatopoda) en el Atlántico oriental y Mediterráneo occidental

En esta nota se informa sobre la presencia del estoma­tópodo Parasquilla ferussaci en las costas de la península ibérica. La documentación está basada en tres especímenes capturados, respectivamente, en Isla Cristina (Huelva) en el Golfo de Cádiz, Fuengirola (Málaga) en el Mar de Alborán y en Gavà (Barcelona) en el Me­diterráneo noroccidental. Se amplia la distribución conocida de la especie completando así el vacío existente hasta el momento entre las citas atlánticas y las del Mediterráneo central. Palabras clave: Parasquilla ferussaci, Estomatópodo, Mediterráneo occidental, Golfo de Cádiz.We report the occurrence of the little known stomatopod Parasquilla ferussaci on the Atlantic and Mediterranean coasts of the Iberian peninsula. Documentation is based on three specimens captured off Isla Cristina (Huelva) in the Gulf of Cadiz, off Fuengirola (Málaga) in the Alboran Sea and off Gavà (Barcelona) in the North-Western Mediterranean. These reports fill the distribution gap between Eastern Central Atlantic reports and previous Mediterranean reports east of the Balearic Islands. Key words: Parasquilla ferussaci, Stomatopoda, Western Mediterranean, Gulf of Cadiz.En esta nota se informa sobre la presencia del estoma­tópodo Parasquilla ferussaci en las costas de la península ibérica. La documentación está basada en tres especímenes capturados, respectivamente, en Isla Cristina (Huelva) en el Golfo de Cádiz, Fuengirola (Málaga) en el Mar de Alborán y en Gavà (Barcelona) en el Me­diterráneo noroccidental. Se amplia la distribución conocida de la especie completando así el vacío existente hasta el momento entre las citas atlánticas y las del Mediterráneo central. Palabras clave: Parasquilla ferussaci, Estomatópodo, Mediterráneo occidental, Golfo de Cádiz

Trabajo temporal y siniestralidad laboral en España en el período 1988 - 1995.

Sin resume

Drag force in a string model dual to large-N QCD

We compute the drag force exerted on a quark and a di-quark systems in a background dual to large-N QCD at finite temperature. We find that appears a drag force in the former setup with flow of energy proportional to the mass of the quark while in the latter there is no dragging as in other studies. We also review the screening length.Comment: 15 pages, typos removed, error corrected, refs adde

New directions in management strategy evaluation through cross-fertilisation between fisheries science and terrestrial conservation

et al.On 1 and 2 June 2010, an international meeting was held at the University of Paris Sud XI, France, organized within the framework of the EU FP7 consortium project HUNT, to bring together fisheries and conservation scientists to discuss a unified framework for the future of management strategies for harvested species.E.J.M.G. acknowledges the support of a Royal Society Wolfson Research Merit award. This workshop was supported by the European Commission under the HUNT project of the 7th Framework Programme for Research and Technological Development.Peer Reviewe