234 research outputs found

    Facies y control tectónico de la cuenca Eocena Subpirenaica Catalana

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    En la cuenca Subpirenaica Catalana (NE de España) pueden definirse durante el Eoceno inferior tres áreas de sedimentación caracterizadas por grupos deposicionales diferentes. Los límites entre estas tres áreas sedimentarias coinciden con fracturas del zócalo Herciniano de dirección NW-SE. La reactivación de estas fallas en el Eoceno inferior coincide con el inicio de los movimientos relacionados con el levantamiento del Pirineo, y condiciona la sedimentación terrígena. Su actuación durante el Eoceno se pone claramente de manifiesto en Cataluña al considerar los límites entre las diversas subcuencas de la cuenca Central Catalana

    Relación entre sedimentos terrígenos costeros, facies arrecifales y evaporitas. El modelo de Centelles y su aplicación regional

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    El modelo de sedimentación de la Cuenca Eocena Catalana puede ser explicado mediante un número reducido de facies (terrígenas, carbonatadas y evaporíticas) estrechamente relacionadas entre sí. Las facies terrígenas (fan-delta, delta y barras mareales) condicionaron dinámica y morfológicamente el desarrollo de crecimientos arrecifales en el espacio y en el tiempo. Se plantea un modelo completo de esta relación que puede ser aplicado a toda la cuenca Eocena

    Relación entre sedimentos terrígenos costeros, facies arrecifales y evaporitas. El modelo de Centelles y su aplicación regional

    Get PDF
    El modelo de sedimentación de la Cuenca Eocena Catalana puede ser explicado mediante un número reducido de facies (terrígenas, carbonatadas y evaporíticas) estrechamente relacionadas entre sí. Las facies terrígenas (fan-delta, delta y barras mareales) condicionaron dinámica y morfológicamente el desarrollo de crecimientos arrecifales en el espacio y en el tiempo. Se plantea un modelo completo de esta relación que puede ser aplicado a toda la cuenca Eocena

    Palaeohydrology of the Mulhouse Basin: are fluid inclusions in halite tracers of past seawater composition?

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    Brine reactions processes were the most important factors controlling the major-ion evolution in the Oligocene, Mulhouse Basin (France) evaporite basin. The combined analysis of fluid inclusions in primary textures in halite by Cryo-SEM-EDS with sulfate-δ34S, δ18O and 87Sr/86Sr isotope ratios reveals hydrothermal inputs and recycling of Permian evaporites, particularly during advanced stages of evaporation in the Salt IV member which ended with sylvite formation. The lower part of the Salt IV evolved from an originally marine input. Sulfate-δ34S shows Oligocene marine-like signatures at the base of the member (Fig.1). However, enriched sulfate-δ18O reveals the importance of re-oxidation processes. As evaporation progressed other non-marine or marine-modified inputs from neighbouring basins became more important. This is demonstrated by an increase in K concentrations in brine inclusions, Br in halite and variations in sulfate isotopes trends and 87Sr/86Sr ratios. The recycling of previously precipitated evaporites was increasingly important with evaporation. Therefore, regardless of the apparent marine sequence (gypsum, halite, potassic salts), the existence of diverse inputs and the consequent chemical changes to the brine preclude the use of trapped brine inclusions in direct reconstruction of Oligocene seawater chemistry.European Association for Geochemistry; Geochemical Societ

    The 'Tortonian salinity crisis' of the eastern Betics (Spain)

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    The late Miocene depositional history of the Lorca and Fortuna basins, both occupying an internal position in the eastern Betics of Spain, is marked by a regressive sequence from open marine marls, via diatomites and evaporites, to continental sediments. Based on facies similarities, these evaporites have often been correlated to the well-known Mediterranean evaporites of the Messinian salinity crisis, although this correlation was never substantiated by reliable chronological data. In this paper, we present an integrated stratigraphy of this regressive sequence which shows that the evaporites of the Lorca and Fortuna basins are entirely of late Tortonian age and as such have no relation with the Messinian salinity crisis. The main phase of basin restriction, resulting in deposition of diatomites and evaporites, took place at 7.8 Ma, while the last marine deposits (massive evaporites of the Lorca basin) are dated at 7.6 Ma. Consequently, this `Tortonian salinity crisis' of the eastern Betics had a duration of approximately 200 kyr, while continental deposition prevailed throughout the entire Messinian as also revealed by the fossil mammal record. The `Tortonian salinity crisis' of the eastern Betics is obviously related to a local phase of basin restriction caused by uplift of the metamorphic complexes at the basin margins, probably in concert with strike-slip activity along SW-NE trending fault systems. The development of a submarine sill is of crucial importance for the increase in salinity because it allows marine waters to continuously enter the basin at the surface while it restricts or prevents the outflow of dense saline waters at depth. Furthermore, we show that evaporite and diatomite cyclicity in these restricted basins is predominantly related to precession controlled circum-Mediterranean climate changes and that glacio-eustatic sea level changes only play a minor role. It is remarkable that the lithological sequence of the Tortonian salinity crisis mimics in many aspects that of the Messinian salinity crisis. This suggests that the diatomaceous facies is an essential part of the lithological sequence associated with basin restriction

    Design and testing of an MRI-compatible cycle ergometer for non-invasive cardiac assessments during exercise

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    <p>Abstract</p> <p>Background</p> <p>Magnetic resonance imaging (MRI) is an important tool for cardiac research, and it is frequently used for resting cardiac assessments. However, research into non-pharmacological stress cardiac evaluation is limited.</p> <p>Methods</p> <p>We aimed to design a portable and relatively inexpensive MRI cycle ergometer capable of continuously measuring pedalling workload while patients exercise to maintain target heart rates.</p> <p>Results</p> <p>We constructed and tested an MRI-compatible cycle ergometer for a 1.5 T MRI scanner. Resting and sub-maximal exercise images (at 110 beats per minute) were successfully obtained in 8 healthy adults.</p> <p>Conclusions</p> <p>The MRI-compatible cycle ergometer constructed by our research group enabled cardiac assessments at fixed heart rates, while continuously recording power output by directly measuring pedal force and crank rotation.</p

    We ask: What is the diagnosis?

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    Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de Diagnóstico por ImagemUniversity of British Columbia Vancouver General Hospital Departamento de RadiologiaUNIFESP, EPM, Depto. de Diagnóstico por ImagemSciEL

    Evaluation of the LSA-SAF gross primary production product derived from SEVIRI/MSG data (MGPP)

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    The objective of this study is to describe a completely new 10-day gross primary production (GPP) product (MGPP LSA-411) based on data from the geostationary SEVIRI/MSG satellite within the LSA SAF (Land Surface Analysis SAF) as part of the SAF (Satellite Application Facility) network of EUMETSAT. The methodology relies on the Monteith approach. It considers that GPP is proportional to the absorbed photosynthetically active radiation APAR and the proportionality factor is known as the light use efficiency ε. A parameterization of this factor is proposed as the product of a εmax, corresponding to the canopy functioning under optimal conditions, and a coefficient quantifying the reduction of photosynthesis as a consequence of water stress. A three years data record (2015–2017) was used in an assessment against site-level eddy covariance (EC) tower GPP estimates and against other Earth Observation (EO) based GPP products. The site-level comparison indicated that the MGPP product performed better than the other EO based GPP products with 48% of the observations being below the optimal accuracy (absolute error < 1.0 g m−2 day−1) and 75% of these data being below the user requirement threshold (absolute error < 3.0 g m−2 day−1). The largest discrepancies between the MGPP product and the other GPP products were found for forests whereas small differences were observed for the other land cover types. The integration of this GPP product with the ensemble of LSA-SAF MSG products is conducive to meet user needs for a better understanding of ecosystem processes and for improved understanding of anthropogenic impact on ecosystem services.The objective of this study is to describe a completely new 10-day gross primary production (GPP) product (MGPP LSA-411) based on data from the geostationary SEVIRI/MSG satellite within the LSA SAF (Land Surface Analysis SAF) as part of the SAF (Satellite Application Facility) network of EUMETSAT. The methodology relies on the Monteith approach. It considers that GPP is proportional to the absorbed photosynthetically active radiation APAR and the proportionality factor is known as the light use efficiency epsilon. A parameterization of this factor is proposed as the product of a epsilon(max), corresponding to the canopy functioning under optimal conditions, and a coefficient quantifying the reduction of photosynthesis as a consequence of water stress. A three years data record (2015-2017) was used in an assessment against site-level eddy covariance (EC) tower GPP estimates and against other Earth Observation (EO) based GPP products. The site-level comparison indicated that the MGPP product performed better than the other EO based GPP products with 48% of the observations being below the optimal accuracy (absolute error <1.0 g m(-2) day(-1)) and 75% of these data being below the user requirement threshold (absolute error <3.0 g m(-2) day(-1)). The largest discrepancies between the MGPP product and the other GPP products were found for forests whereas small differences were observed for the other land cover types. The integration of this GPP product with the ensemble of LSA-SAF MSG products is conducive to meet user needs for a better understanding of ecosystem processes and for improved understanding of anthropogenic impact on ecosystem services.Peer reviewe

    Interchangeability of position tracking technologies; can we merge the data?

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    Purpose: The purpose of this study was to assess the interchangeability of position tracking metrics obtained using global positioning systems (GPS) versus those obtained by a semi-automatic high definition (HD) optical camera system. Methods: Data was collected from a cohort of 29 elite soccer players (age: 23.1 ± 5.1 years, height: 180.4 ± 5.8 cm, mass: 74.6 ± 6.7 kg) in four matches played in four different stadiums. In two matches 10Hz GPS (GPS-1, StatSports, Belfast, UK) were used, while in the other two matches augmented 10Hz GPS (GPS-2, StatSports, Belfast, UK) were used. All four matches were analysed concomitantly using six semi-automated HD motion cameras sampling at 25Hz (TRACAB, Chyronhego, New York, USA). Results: Mean bias was between 6-10% for GPS-1 and 1-4% for GPS-2 respectively. No proportional bias was found (p > 0.184). The SEE within calibration functions (expressed in % to mean) was between 5-22% for GPS-1 and 4-14% for GPS-2. While some significant differences existed between GPS-1 and TRACAB (total distance and high-speed), positional tracking variables were highly correlated between GPS-1, GPS-2 and TRACAB (r2 > 0.92) with GPS-2 displaying stronger correlations (> r2 = 0.96). Conclusion: In the present study augmented GPS technology (GPS-2) and the TRACAB camera system provided interchangeable measures of positional tracking metrics to allow concurrent assessment and monitoring of training and competition in soccer players. However, we recommend practitioners evaluate their own systems to identify where errors exist and re-calibrate accordingly to confidently interchange data

    Tourism destination competitiveness: second thoughts on the world economic forum reports

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    The Travel and Tourism Competitiveness Reports of the World Economic Forum elaborate the Travel and Tourism Competitiveness Index (TTCI) as an overall measure of destination competitiveness for 130 economies worldwide. From a tourism management point of view, a measure such as the TTCI is expected to be instrumental in explaining and predicting the tourism performance of receiving countries. This study explores several ways to transform the TTCI into a formative structural model. Partial least squares path modelling, PLS regression, mixture modelling and non-linear covariance-based structural equation modelling are applied to examine the TTCI's predictive power. The analysis probes possible measures for improvement. The destination countries may be subject to unobserved heterogeneity with regard to how the various constituents of competitiveness act on tourism performance. Interaction phenomena seem to prohibit a simple cause-effect pattern and non-linear relationships show encouraging results
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