46 research outputs found
Structure des grands bassins glaciaires dans le nord de la péninsule ibérique: comparaison entre les vallées d'Andorre (Pyrénées orientales), du Gållego (Pyrénées centrales) et du Trueba (Chaßne Cantabrique).
Les grandes vallĂ©es glaciaires de la PĂ©ninsule IbĂ©rique sont situĂ©es dans la chaĂźne pyrĂ©nĂ©o-cantabrique, principalement dans le bassin de l'Ăbre. Ainsi, les vallĂ©es d'Andorre, de la Noguera Pallaresa et de la haute vallĂ©e du GĂĄllego, dans les PyrĂ©nĂ©es, ont eu des appareils glaciaires longs de 42, 50 et 40 km respectivement. Dans les vallĂ©es du Sil (bassin du Miño) et du Trueba, dans la ChaĂźne Cantabrique, ils atteignaient 42 et 16,5 km (Serrano-Cañadas, 1996 ; GĂłmez-Ortiz et al., 2001 ; Turu & Peña, 2006a et b ; Redondo-Vega et al., 2006). L'une des caractĂ©ristiques gĂ©omorphologiques de la plupart de ces vallĂ©es est l'existence d'une dĂ©pression morphologique du substratum dans les parties moyennes et terminales, interprĂ©tĂ©e comme la consĂ©quence de l'Ă©rosion glaciaire. Dans tous les cas, on observe une architecture litho-stratigraphique commune (Vilaplana & Casas, 1983 ; Bordonau et al., 1989 ; Bordonau, 1992 ; Turu et al., 2002) reprĂ©sentĂ©e par trois unitĂ©s gĂ©oĂ©lectriques : une unitĂ© infĂ©rieure trĂšs Ă©paisse, avec des rĂ©sistivitĂ©s Ă©lectriques basses (70 - 200 Ohms par mĂštre), qui traduit la prĂ©sence de matĂ©riaux fins considĂ©rĂ©s comme d'origine lacustre ; une unitĂ© intermĂ©diaire, moins Ă©paisse, avec des valeurs de rĂ©sistivitĂ© plus Ă©levĂ©es (400 - 800 Ohms par mĂštre), pouvant ĂȘtre interprĂ©tĂ©e comme un systĂšme fluvio-deltaĂŻque pro-glaciaire et une unitĂ© gĂ©oĂ©lectrique supĂ©rieure, avec des valeurs de rĂ©sistivitĂ© trĂšs variables (100 - 1500 Ohms par mĂštre), constituĂ©e de sĂ©diments alluviaux subactuels. La comparaison des donnĂ©es de type gĂ©ophysique et gĂ©omĂ©canique (sismique Ă rĂ©fraction et essais pressiomĂ©triques) montre que l'unitĂ© intermĂ©diaire, considĂ©rĂ©e comme d'origine fluvio-deltaĂŻque, prĂ©sente des valeurs de vitesse sismique anormalement Ă©levĂ©es, ainsi que de hautes valeurs de consolidation. Cette observation effectuĂ©e pour la premiĂšre fois dans la vallĂ©e d'Andorre (Turu, 2000) montre des remarquables corrĂ©lations entre les hautes vitesses sismiques et les valeurs Ă©levĂ©es de consolidation, ainsi que la trĂšs nette corrĂ©lation entre les hautes valeurs de consolidation et les tills sous-glaciaires. Elle permet d'interprĂ©ter l'unitĂ© intermĂ©diaire comme essentiellement glaciaire et de remettre en question le modĂšle simple d'une sĂ©quence de comblement lacustre et deltaĂŻque proposĂ© jusquÂŽĂ maintenant
Geodetic Research on Deception Island and its Environment (South Shetland Islands, Bransfield Sea and Antarctic Peninsula) During Spanish Antarctic Campaigns (1987-2007)
Since 1987, Spain has been continuously developing several scientific
projects, mainly based on Earth Sciences, in Geodesy, Geochemistry, Geology or
Volcanology. The need of a geodetic reference frame when doing hydrographic and
topographic mapping meant the organization of the earlier campaigns with the
main goals of updating the existing cartography and of making new maps of the
area. During this period of time, new techniques arose in Space Geodesy
improving the classical methodology and making possible its applications to
other different fields such as tectonic or volcanism. Spanish Antarctic
Geodetic activities from the 1987/1988 to 2006/2007 campaigns are described as
well as a geodetic and a levelling network are presented. The first network,
RGAE, was designed and established to define a reference frame in the region
formed by the South Shetlands Islands, the Bransfield Sea and the Antarctic
Peninsula whereas the second one, REGID, was planned to control the volcanic
activity in Deception Island. Finally, the horizontal and vertical deformation
models are described too, as well as the strategy which has been followed when
computing an experimental geoid
Orphan crops of archaeology-based crop history research
So-called âforgottenâ or âorphanâ crops are an important component of strategies aimed at preserving and promoting biodiversity. Knowledge of historical cultivation, usage, and geographic and evolutionary trajectories of plants, that is, crop history research, is important for the long-term success of such efforts. However, research biases in the crops chosen for study may present hurdles. This review attempts to systematically identify patterns in crop species representativeness within archaeology-based crop history research. A meta-analysis and synthesis of archaeo- botanical evidence (and lack thereof) is presented for 268 species known to have been cultivated for food prior to 1492 CE from the Mediterranean region to South Asia. We identified 39 genera with known crop plants in this geographical and histor- ical context that are currently absent from its archaeobotanical record, constituting âorphanâ crops of archaeobotany. In addition, a worldwide synthesis of crop species studied using geometric morphometric, archaeogenetic and stable isotope analyses of archaeological plant remains is presented, and biases in the species represented in these disciplines are discussed. Both disciplinary methodological biases and economic agenda-based biases affecting species representativeness in crop history research are apparent. This study also highlights the limited geographic diffusion of most crops and the potential for deeper historical perspectives on how crops become marginal- ized and âforgottenâ
Overview of recent TJ-II stellarator results
The main results obtained in the TJ-II stellarator in the last two years are reported. The most important topics investigated have been modelling and validation of impurity transport, validation of gyrokinetic simulations, turbulence characterisation, effect of magnetic configuration on transport, fuelling with pellet injection, fast particles and liquid metal plasma facing components. As regards impurity transport research, a number of working lines exploring several recently discovered effects have been developed: the effect of tangential drifts on stellarator neoclassical transport, the impurity flux driven by electric fields tangent to magnetic surfaces and attempts of experimental validation with Doppler reflectometry of the variation of the radial electric field on the flux surface. Concerning gyrokinetic simulations, two validation activities have been performed, the comparison with measurements of zonal flow relaxation in pellet-induced fast transients and the comparison with experimental poloidal variation of fluctuations amplitude. The impact of radial electric fields on turbulence spreading in the edge and scrape-off layer has been also experimentally characterized using a 2D Langmuir probe array. Another remarkable piece of work has been the investigation of the radial propagation of small temperature perturbations using transfer entropy. Research on the physics and modelling of plasma core fuelling with pellet and tracer-encapsulated solid-pellet injection has produced also relevant results. Neutral beam injection driven Alfvénic activity and its possible control by electron cyclotron current drive has been examined as well in TJ-II. Finally, recent results on alternative plasma facing components based on liquid metals are also presented. ISSN:0029-5515 ISSN:1741-432
Overview of recent TJ-II stellarator results
The main results obtained in the TJ-II stellarator in the last two years are reported. The most important topics investigated have been modelling and validation of impurity transport, validation of gyrokinetic simulations, turbulence characterisation, effect of magnetic configuration on transport, fuelling with pellet injection, fast particles and liquid metal plasma facing components. As regards impurity transport research, a number of working lines exploring several recently discovered effects have been developed: the effect of tangential drifts on stellarator neoclassical transport, the impurity flux driven by electric fields tangent to magnetic surfaces and attempts of experimental validation with Doppler reflectometry of the variation of the radial electric field on the flux surface. Concerning gyrokinetic simulations, two validation activities have been performed, the comparison with measurements of zonal flow relaxation in pellet-induced fast transients and the comparison with experimental poloidal variation of fluctuations amplitude. The impact of radial electric fields on turbulence spreading in the edge and scrape-off layer has been also experimentally characterized using a 2D Langmuir probe array. Another remarkable piece of work has been the investigation of the radial propagation of small temperature perturbations using transfer entropy. Research on the physics and modelling of plasma core fuelling with pellet and tracer-encapsulated solid-pellet injection has produced also relevant results. Neutral beam injection driven AlfvĂ©nic activity and its possible control by electron cyclotron current drive has been examined as well in TJ-II. Finally, recent results on alternative plasma facing components based on liquid metals are also presentedThis work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014â2018 under Grant Agreement No. 633053. It has been partially funded by the Ministerio de Ciencia, InovaciĂłn y Universidades of Spain under projects ENE2013-48109-P, ENE2015-70142-P and FIS2017-88892-P. It has also received funds from the Spanish Government via mobility grant PRX17/00425. The authors thankfully acknowledge the computer resources at MareNostrum and the technical support provided by the Barcelona S.C. It has been supported as well by The Science and Technology Center in Ukraine (STCU), Project P-507F
International lower limb collaborative (INTELLECT) study: a multicentre, international retrospective audit of lower extremity open fractures
Trauma remains a major cause of mortality and disability across the world1, with a higher burden in developing nations2. Open lower extremity injuries are devastating events from a physical3, mental health4, and socioeconomic5 standpoint. The potential sequelae, including risk of chronic infection and amputation, can lead to delayed recovery and major disability6. This international study aimed to describe global disparities, timely intervention, guideline-directed care, and economic aspects of open lower limb injuries
International Lower Limb Collaborative (INTELLECT) study : a multicentre, international retrospective audit of lower extremity open fractures
Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic
This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic