Organic Carbon Burial following the Middle Eocene Climatic Optimum (MECO) in the central - western Tethys

We present trace metal geochemistry and stable isotope records for the middle Eocene Alano di Piave section, NE Italy, deposited during magnetochron C18n in the marginal Tethys Ocean. We identify a $\sim$ 500 kyr long carbon isotope perturbation event we infer to be the middle Eocene Climatic Optimum (MECO) confirming the northern hemisphere expression and global occurrence of MECO. Interpreted peak climatic conditions are followed by the rapid deposition of two organic rich intervals ($\le$3\% TOC) and contemporaneous positive $\delta^{13}$C excursions. These two intervals are associated with increases in the concentration of sulphur and redox-sensitive trace metals, and low concentrations of Mn, as well as coupled with the occurrence of pyrite. Together these changes imply low, possibly dysoxic, bottom water O$_{2}$ conditions promoting increased organic carbon burial. We hypothesize that this rapid burial of organic carbon lowered global {\it p}CO$_{2}$ following the peak warming and returned the climate system to the general Eocene cooling trend

Bottleneck at Jaramillo for human migration to Iberia and the rest of Europe?

In the contemporary paleoanthropological literature, there is a general consensus that the earliest peopling of Europe occurred before the Brunhes–Matuyama geomagnetic polarity reversal at 0.78 Ma, based on convincing magnetostratigraphic evidence from Spain (e.g., Carbonell et al., 1995 and Parés and Perez-Gonzalez, 1999), Italy (Muttoni et al., 2011), and northern Europe (e.g., Parfitt et al., 2005). However, there is intense debate about how much before 0.78 Ma the earliest peopling occurred. Proponents of a long chronology claim that Europe was inhabited well before 1 Ma. There are sites that imply peopling of Europe before the Jaramillo normal geomagnetic polarity subchron (1.07–0.99 Ma; time scale of Lourens et al., 2004), even though the Jaramillo is nowhere to be found in these sections. Proponents of a shorter chronology (Muttoni et al., 2010, Muttoni et al., 2013 and Muttoni et al., 2014) put emphasis on the presence (or absence) of the Jaramillo in key hominin sections, while calling attention to large uncertainties in some of the other dating methods (biostratigraphic, ESR, cosmogenic), to infer that the earliest peopling of Europe occurred in a narrow time window of reverse polarity prior to the Brunhes–Matuyama boundary (0.78 Ma) but after the Jaramillo subchron (0.99–1.07 Ma). The Jaramillo has therefore attained the status of a marker datum useful for separating the long (>1 Ma) from the short (<1 Ma) chronology of the earliest peopling of Europe

Age and Depositional Environment of Whale-Bearing Sedimentary Succession from the Lower Pliocene of Tuscany (Italy): Insights from Palaeomagnetism, Calcareous Microfossils and Facies Analyses

A c. 31 m thick section straddling the fossil find of an Early Pliocene baleen whale ("Brunella", hereafter), made in 2007 in the sedimentary fill of the Middle Ombrone Basin of Tuscany, is investigated for depositional age and environment combining palaeomagnetic, micropalaeontological (Foraminifera and calcareous nannofossils) and sedimentary facies analyses. Resting unconformably onto Late Miocene continental deposits, the Early Pliocene marine deposits include, from bottom to top, a coarse-grained wave-winnowing lag, the few metres-thick fossiliferous sandstone bedset from which Brunella was unearthed, and several metres of clays. The stratigraphic organisation of these deposits indicate deposition in a deepening upward inner shelf environment. Successful isolation of characteristic remanent magnetisation and calcareous nannofossil content indicate the investigated marine section was deposited during the interval of polarity Chron C3n.2n corresponding to the basal part of the Mediterranean nannofossil zone MNN13 (between Helicosphaera sellii Base common and the Amaurolithus primus Top) and allow estimating the depositional age of Brunella to c. 4.6 Ma. Sedimentary facies, benthic Foraminifera association and anisotropy of magnetic susceptibility characterising the deposits that embedded Brunella suggest deposition above the fair-weather base level

¿Cuál debería ser el nivel de sencillez ideal para un análisis no lineal de elementos en hormigón estructural?

This paper discusses on the required level of simplicity for suitable modelling of structural concrete. Traditional equilibrium- based approaches (as strut-and-tie models) are too coarse in some cases, as they account for the cracking state of concrete in a sometimes excessively simplified manner. The alternative of complex nonlinear numerical modelling is also not always satisfactory for design as the number of parameters required, their definition and the sensitivity of the structural response to them is complex and requires a high level of experience. Contrary to these approaches, this paper introduces the elastic plastic stress field method. This method is grounded on the theory of plasticity but allows considering deformation compatibility. The results are consistent both in terms of the strength and deformation field of the member. It also has the advantage of requiring only two physical material properties (modulus of elasticity and plastic strength) which can be easily determined by designers.Este artículo discute sobre el nivel de sencillez ideal para un análisis no lineal de elementos de hormigón estructural. Los métodos de cálculo basados únicamente en condiciones de equilibrio (como los modelos de bielas-y-tirantes) no son siempre adecuados ya que el estado de fisuración del hormigón se considera a veces de una manera excesivamente simplificada. Los análisis no lineales complejos tampoco son siempre adecuados, ya que el número de parámetros requeridos, su definición y la sensibilidad de la respuesta del elemento a sus variaciones requieren una gran experiencia. Como alternativa, se presenta el método de los campos de tensiones elasto-plásticos. Este método se basa en la teoría de la plasticidad pero incorporando condiciones de compatibilidad. Los resultados son coherentes en términos de resistencia y de deformaciones. Además, sólo necesita la definición de dos parámetros mecánicos (módulo de elasticidad y resistencia plástica) que pueden ser fácilmente determinados por el proyectista

Paleomagnetic data from Late Paleozoic dykes of Sardinia: evidence for block rotations and implications for the intra-Pangea megashear system

Paleomagnetic studies of dyke swarms from the Variscan belt of Europe can be used to reconstruct internal postorogenic rotations within the fold belt. Here we present paleomagnetic data from 13 late Variscan dykes from Sardinia ranging in age from 298\ub15 to 270\ub110 Ma. The dykes can be grouped on the basis of their different directions in strike in a northern, a central-eastern and a south-eastern province. Paleomagnetic component directions have been obtained using thermal and alternating field demagnetization techniques, which give reproducible results. The paleomagnetic mean directions differ significantly between northern Sardinia and south-eastern and central-eastern Sardinia, the latter two regions yielding statistically similar paleomagnetic mean directions. These results indicate that Sardinia fragmented into two, arguably three, crustal blocks after emplacement of the dykes, which experienced differential relative rotations, as is also indicated by the differences in overall strike directions. The determination of timing, sense, and magnitude of these rotations has major implications for the reconstruction of the geodynamic evolution of the region in post-Carboniferous times. We argue that the observed block rotations occurred during the Permian as the result of post-Variscan intra-Pangea mobility possibly related to the transformation of an Early Permian Pangea B to a Late Permian Pangea A. \ua9 2014. American Geophysical Union. All Rights Reserved

Decompressive craniectomy in paediatric traumatic brain injury: a systematic review of current evidence

Introduction Paediatric traumatic brain injury (pTBI) is one of the most frequent neurological presentations encountered in emergency departments worldwide. Every year, more than 200,000 American children suffer pTBIs, many of which lead to long-term damage. Objectives We aim to review the existing evidence on the efficacy of the decompressive craniectomy (DC) in controlling intracranial pressure (ICP) and improving long-term outcomes in children with pTBI. Methods A comprehensive search of the MEDLINE and EMBASE databases led to the screening of 212 studies, 12 of which satisfied inclusion criteria. Data extracted included the number and ages of patients, Glasgow Coma Scale scores at presentation, treatment protocols and short- and long-term outcomes. Results Each of the nine studies including ICP as an outcome reported that it was successfully controlled by DC. The 6–12 month outcome scores of patients undergoing DC were positive, or superior to those of medically treated groups in nine of 11 studies. Mortality was compared in only two studies, and was lower in the DC group in both.Very few studies are currently available investigating short- and long-term outcomes in children with TBI undergoing DC. Conclusion The currently available evidence may support a beneficial role of DC in controlling ICP and improving long-term outcomes

Comportement, calcul et dimensionnement des tranchées couvertes

La recherche effectuée sur les tranchées couvertes, ou tunnels exécutés à ciel ouvert, apporte une contribution théorique à la compréhension du comportement de ces ouvrages jusqu’à l’état limite ultime. Une méthode simplifiée inspirée de la méthode convergence-confinement est développée puis appliquée à plusieurs cas représentatifs. Cette méthode, basée sur le mécanisme de rupture de la structure, donne une solution approchée de l’état d’équilibre entre le sol et la structure. A ce titre, elle constitue un outil de conception car elle facilite la compréhension des mécanismes d’interaction sol-structure complexes caractéristiques de ces ouvrages. Le comportement du sol en interaction avec la structure est caractérisé typiquement par deux phases principales. La phase élastique est suivie par la plastification progressive de certaines zones du sol jusqu’à former un mécanisme plastique (phase plastique). Selon la géométrie et les matériaux, la structure profite alors plus ou moins favorablement de la contribution du sol à la reprise des charges. La conclusion principale de ce travail est l’existence de plusieurs régimes de comportement. Trois régimes principaux d’un intérêt pratique particulier, définis principalement par la phase de comportement du sol déterminante pour la structure, sont mis en évidence : sol élastique, sol élasto-plastique et sol complètement plastifié. L’identification du régime permet alors de concevoir efficacement la structure et renseigne sur les éléments importants à considérer lors du calcul et du dimensionnement. L’étude a également permis de montrer que la méthode dite aux modules de réaction n’est utilisable que dans certains cas bien définis. Dans les autres cas, la méthode aux éléments finis devrait être utilisée. Un nouveau format de sécurité compatible avec la nouvelle génération de normes SIA est proposé pour définir l’état limite ultime de la structure lors de l’utilisation de la méthode aux éléments finis. Ce format uniformise et clarifie la procédure de dimensionnement de ces structures. La recherche a aussi montré que la ductilité de la structure joue un rôle prépondérant pour garantir ou non l’exploitation des réserves de capacité offertes par le sol. Plusieurs limites de ductilité critiques pour les tranchées couvertes sont mises en évidence. Pour les tranchées couvertes de type cadre, la capacité de déformation de la dalle supérieure est très faible si aucun étrier n’est disposé dans les zones fortement sollicitées à l’effort tranchant. Pour les tranchées couvertes de type voûte, le phénomène d’éclatement du béton d’enrobage peut limiter la capacité de déformation de la structure. Des essais réalisés en laboratoire ont montré que la résistance à ce phénomène était influencée négativement par les déformations plastiques de l’armature et par la présence de joints de recouvrement. L’article 5.2.7.1 de la norme SIA 262 (2003) est jugée insuffisante. Des règles de vérification tirées des essais sont proposées. Le calcul de ces structures avec de grandes redistributions plastiques n’est alors possible que sous certaines conditions garantissant une ductilité suffisante