Pistas fósiles asociadas a la discontinuidad fini-Messiniense en el margen norte de la Cuenca del Bajo Segura (SE España)

A detailed analysis of the Upper Messinian-Lower Pliocene at the northern border of the Bajo Segura Basin (BSB) has been carried out. Trace fossils of firm- and rockground were collected, aiding in the recognition of three ichnofacies: Glossifungites (types A and B), Entobia and Gnathichnus. The ichnological data provide evidence that the Pliocene flooding of the BSB, after the Messinian Salinity Crisis, was developed in two pulses. In the first one, the ingression penetrated only along the paleovalleys and produced a coastal trasgressive lag (P0). In the second one, the ingression overflowed the margins of the paleovalleys and extended throughout the entire northern margin, also producing a coastal transgressive lag in the base of the P2 system. The record of the Entobia and Gnathichnus ichnofacies in the clasts of both lags evidences a relatively fast deepening-upward trend in both the transgressions.

Impacto de las notas de prensa en las citas recibidas por los artículos publicados en Gaceta Sanitaria

Antecedentes/Objetivos: Hay pocos estudios que analicen los factores que influyen sobre el factor de impacto bibliométrico de una revista y las notas de prensa son uno de estos factores. Se presenta un análisis del impacto en las citas recibidas por los artículos objeto de una nota de prensa elaborada desde Gaceta Sanitaria. Métodos: Se elaboró una base de datos con todos los artículos publicados en Gaceta Sanitaria entre 2007 y 2011. Para cada uno se registró el número de citas recibidas hasta el año 2012 (incluido) en la base de datos Web of Science. Para cada artículo se registró si había sido incluido o no en las notas de prensa elaboradas desde la revista. Desde 2007 hasta 2011 dos artículos de cada número han sido objeto de una nota de prensa por término medio, aunque en algún número sólo hubo una nota de prensa. Las notas de prensa fueron para artículos originales y artículos breves, por lo que en este análisis se incluyen exclusivamente los artículos publicados bajo estos formatos. Se comparó la mediana de citaciones recibidas y los rangos intercuartílicos (RIC) entre los artículos originales breves y artículos originales objeto de nota de prensa frente a aquellos artículos originales sin nota de prensa. También se obtuvieron las citaciones y rangos intercuartílicos para las revisiones. Resultados: En el periodo considerado, se publicaron en Gaceta Sanitaria un total de 286 originales (de los que el 19% eran originales breves, n = 54). De este total, 47 artículos (16% del total) fueron incluidos en las notas de prensa preparadas desde la revista (incluyendo 4 originales breves). El resto de trabajos publicados en el mismo período no fueron objeto de nota de prensa (189 originales y 50 originales breves). La mediana de citaciones de los artículos sin nota de prensa fue de 1 (RIC 0-3), mientras que para los artículos con nota de prensa fue de 3 (RIC 1-5). La prueba de comparación de medianas dio un valor de p = 0,038. Por otra parte, en el mismo período se publicaron en Gaceta 19 revisiones, que recibieron una mediana de 3 citas (RIC 1-6), siendo estos resultados muy similares a los obtenidos en el análisis para los artículos originales con nota de prensa (p = 0,967). Conclusiones: Las notas de prensa elaboradas desde Gaceta se asocian al número de citas recibidas por los artículos originales y originales breves, siendo los resultados comparables a los que alcanzan las revisiones. Un ensayo clínico aleatorizado sería la manera ideal de comparar el verdadero impacto en las citaciones de la selección de un artículo original para una nota de prensa.

Spatial Distribution of Marine Epibenthic Communities in the Hola Trough (Vesterålen, Northern Norway)

The Lofoten-Vesterålen marine shelf is one of the most geologically diverse coast and offshore margin areas in Norway. This leads to huge heterogeneity in marine environments, and often high biodiversity. However, little is known yet about the benthic communities in this region. Within the ARCTOS LoVe MarineEco project the epibenthic communities of the Hola trough (Vesterålen) are analysed to give a first description of their spatial distribution. In this trough both a complex hydrodynamic system and varied topographic submarine elements occur. Trawling samples were collected for two different approaches: one in a meso-scale and another in a small-scale. For the broad scale a transect consisting in three stations was developed, while for the fine scale a small area on a sand wave field, consisting in five stations called HolaBox, was sampled. All organisms were intended to be identified to species level and colonial fauna was discarded for the analysis. Different diversity indexes were assessed (Shannon index (H’) and Pielou’s eveness (J’)). Clustering and nMDS analyses identified four statistically significant groups in terms of abundance (ind./100m2). A total amount of 211 different taxa were found within all stations. The more outer part of the transect (close to the shelf edge) presented a huge abundance of organisms and was dominated by the hemi sessile tube-builder polychaetes Nothria conchylega and Eunice dubitata and the sea urchin Gacilechinus acutus, while the more inner parts presented less abundance of individuals. Probably some upwelling produced by the Norwegian Atlantic Current (NWAC) is influencing the shelf edge increasing the primary production and, therefore, enriching the seafloor in this region. The sand wave field presented two different groups with few amount of individuals. Small-scale variability could be produced by the high heterogeneity within the different types of sand waves, while the scarce abundance of animals can be produced by the permanent changing environment that movable sand waves produce. Here more active and mobile fauna was found such as brittle stars and hermit crabs (among others). Finally, a fourth group was found in the most inner station of the transect, laying on a ridge in the central part of the trough. This station, with coarse substrate, was mainly dominated again by brittle stars and sea urchins. We can conclude that this is a really heterogeneous trough in environments and therefore in communities (even in a local scale). More detailed studies that focus in the local environmental drivers have to be carried out to get an integrated understanding of the structure of benthic communities in this system.

Non-parametrized functionals with empirical dispersion corrections: A happy match?

The performances of two parametrized functionals (namely B3LYP and B2PYLP) have been compared with those of two non-parametrized functionals (PBE0 and PBE0-DH) on a relatively large benchmark set when three different types of dispersion corrections are applied [namely the D2, D3 and D3(BJ) models]. Globally, the MAD computed using non-parametrized functionals decreases when adding dispersion terms although the accuracy not necessarily increases with the complexity of the model of dispersion correction used. In particular, the D2 correction is found to improve the performances of both PBE0 and PBE0-DH, while no systematic improvement is observed going from D2 to D3 or D3(BJ) corrections. Indeed when including dispersion, the number of sets for which PBE0-DH is the best performing functional decreases at the benefit of B2PLYP. Overall, our results clearly show that inclusion of dispersion corrections is more beneficial to parametrized double-hybrid functionals than to non-parametrized ones. The same conclusions globally hold for the corresponding global hybrids, showing that the marriage between non-parametrized functionals and empirical corrections may be a difficult deal.

Systematic Improvement of Density Functionals through Parameter-Free Hybridization Schemes

It is suggested here that the ultimate accuracy of DFT methods arises from the type of hybridization scheme followed. This idea can be cast into a mathematical formulation utilizing an integrand connecting the noninteracting and the interacting particle system. We consider two previously developed models for it, dubbed as HYB0 and QIDH, and assess a large number of exchange-correlation functionals against the AE6, G2/148, and S22 reference data sets. An interesting consequence of these hybridization schemes is that the error bars, including the standard deviation, are found to markedly decrease with respect to the density-based (nonhybrid) case. This improvement is substantially better than variations due to the underlying density functional used. We thus finally hypothesize about the universal character of the HYB0 and QIDH models.