Efecto de la capacidad visoespacial en el rendimiento académico de estudiantes de anatomía médica

Visuospatial ability is associated with clinical skills in medical education, as it predicts the academic performance of anatomy students. Objective: To determine whether visuospatial processing generates changes in the teaching of medical anatomy and predicts academic performance in that subject. Methods: 140 students were evaluated at the beginning of the semester and before final exams with the Rey Complex Figure Test (CRFT).  Student's t-tests were performed to contrast pre- and post-test differences, Cohen's d to measure effect size, and linear regression to evaluate prediction with final grades. Results: Mean age 20.22 years (SD=1.12), mean grade point average 4.96 (SD=1.20). Seventy percent of the students passed the course. The t-test reports significant differences of TFCR (Memory recall: t=-17.383; p<0.001; Delayed recall: t=-16.547, p<0.001) with a medium effect size (d=0.59 and d=0.56), respectively. The scores obtained in the post-test on the TFCR deferred recall task explained up to 90% of the students' academic performance. Conclusions: The instrument's deferred memory predicted academic performance and anatomy learning improved students' visuospatial function performance.La capacidad visoespacial se asocia con habilidades clínicas en la educación médica, ya que predice el desempeño académico de los estudiantes de anatomía. Objetivo: Determinar si el procesamiento visoespacial genera cambios en la enseñanza de la anatomía médica y predice el desempeño académico en esa asignatura. Método: 140 estudiantes evaluados al inicio de semestre y antes de exámenes finales con el Test de la Figura Compleja de Rey.  Se realizaron análisis t de Student para contrastar las diferencias pre y pos-test, d de Cohen para medir el tamaño de efecto y regresión lineal para evaluar la predicción con las notas finales. Resultados: Edad promedio 20.22 años (DE=1.12), media de calificaciones 4.96 (DE=1.20). El 70% de los estudiantes aprobó la asignatura. La prueba t reporta diferencias significativas del TFCR (Evocación de Memoria: t=-17.383; p<0.001; Evocación diferida: t=-16.547, p<0.001) con un tamaño del efecto mediano (d=0.59 y d=0.56), respectivamente. Las puntuaciones obtenidas en el post-test en la tarea de memoria diferida del TFCR, explicaron hasta en un 90% el desempeño académico de los estudiantes. Conclusiones: La memoria diferida del instrumento predijo el rendimiento académico y el aprendizaje de anatomía mejoró el desempeño en la función visoespacial de los estudiantes

Latest Miocene restriction of the Mediterranean Outflow Water:a perspective from the Gulf of Cádiz

The Mediterranean-Atlantic water mass exchange provides the ideal setting for deciphering the role of gateway evolution in ocean circulation. However, the dynamics of Mediterranean Outflow Water (MOW) during the closure of the Late Miocene Mediterranean-Atlantic gateways are poorly understood. Here, we define the sedimentary evolution of Neogene basins from the Gulf of Cádiz to the West Iberian margin to investigate MOW circulation during the latest Miocene. Seismic interpretation highlights a middle to upper Messinian seismic unit of transparent facies, whose base predates the onset of the Messinian salinity crisis (MSC). Its facies and distribution imply a predominantly hemipelagic environment along the Atlantic margins, suggesting an absence or intermittence of MOW preceding evaporite precipitation in the Mediterranean, simultaneous to progressive gateway restriction. The removal of MOW from the Mediterranean-Atlantic water mass exchange reorganized the Atlantic water masses and is correlated to a severe weakening of the Atlantic Meridional Overturning Circulation (AMOC) and a period of further cooling in the North Atlantic during the latest Miocene

Run-out distance and erosion of debris-flows in the Nile deep-sea fan system: Evidence from lithofacies and micro-palaeontological analyses

International audienceDebrites with different volumes, depositional periods and setting are observed in the Nile deep-sea fan system. Here we present debrites from four late Quaternary environments: (i) within the Rosetta submarine channel at 1700 m; (ii) within small basins created by salt tectonics in the Eastern Province at 1300 m; (iii) on the open slope outside of channels at 2600 m; and (iv) in the distal part of the fan fringe beyond channel terminations at 3050 m water depth. The debrites comprise mud clasts in a generally ungraded muddy sand matrix. They are relatively thin (20-150 cm) in fan fringe, in channel and salt-tectonic basin settings, and somewhat thicker (>8 m) in the open slope setting. Benthic foraminiferal assemblages and variation in the planktonic/benthic foraminiferal ratios are considered as a useful tool for tentatively evaluating the origin of sediment in these debris flows and estimation of their run-out distance. Similar microfaunal contents of clast/matrix combinations document that the debrites in the Rosetta channel and salt-tectonic basin were locally sourced. The debrite from the open slope travelled farther (up to 150 km). Three separate debrites in a fan fringe core were deposited by debris flows that originated over 200 km away in water depths shallower than 1000 m. These far-travelled debris flows appear to have eroded remarkably little sediment as they travelled for ∼200 km across low (0.8-1.2°) gradient seafloor. This lack of erosion is attributed to hydroplaning or increasing pore-fluid pressure at the base of debris flows. This study confirms that remarkably mobile debris flows can travel long distances to produce thin debrites in the distal fringes of submarine fans

Mass-transport deposits on the Rosetta Province (NW Nile deep-sea turbidite system, Egyptian Margin): characteristics, distribution, and potential causal processes

Marine Geology, v. 250, n. 3-4, p. 180-198, 2008. http://dx.doi.org/10.1016/j.margeo.2008.01.016International audienc

A rare late Mississipian flora from Northwestern Europe (Maine-et-Loire Coalfield, Pays de la Loire, France)

International audienceNumerous localities in the Maine-et-Loire coalfield in northwestern France have yielded diverse adpression floras belonging to the Calymmotheca stangeri Zone, indicating an early Namurian (Serpukhovian–late Mississippian) age. The floristic affinities are with the South European Palaeoprovince, although there is some evidence of an ecotonal relationship with the Central European Palaeoprovince to the north. The geological context of the deposits suggest that the floras may represent vegetation from an intra-montane setting, although at lower elevations compared with the Pennsylvanian-age Variscan intra-montane basins. This represents some of the earliest known examples of coal swamp vegetation, although compared with the Pennsylvanian-aged coal swamps there was a significantly higher proportion of lycopsid species and a lower proportion of medullosaleans. Most of the Maine-et-Loire fossiliferous localities yielded diverse assemblages of lycopsids, equisetopsids, ferns and Calymmotheca species, and these were used to develop a pictorial reconstruction of this early coal swamp vegetation. However, two of the localities yielded adpressions and associated palynofloras with a greater predominance of lycopsids and sphenopsids, suggesting vegetation of wetter habitats. Two other localities yielded species of a more Pennsylvanian aspect such as Cardioneuropteris and Karinopteris, which may represent drier substrate vegetation

Triggering factors and tsunamogenic potential of a large submarine mass failure on the western Nile margin (Rosetta area, Egypt)

A large-scale mass-transport deposit (MTD) called Sl6 was recognized on the upper slope of the western Nile margin, downslope from of a 30 km-long scarp located along the outer shelf. Regional mapping indicated that this MTD extends on nearly 505 km2 and involved about 14 km3 of Pleistocene-Holocene sediment. Sl6 was triggered between 10 and 9 kyr BP, during the Holocene sea-level rise and coeval pluvial period (increased river flow). The consequent enhanced sediment supply on the upper slope and the outer shelf area caused local overburdening. This factor combined with the potential accumulation of gas in the sediment and earthquake activity is thought to have been the main factor triggering the Sl6 MTD. From the estimated volume of the MTD, a potential slide-generated tsunami was numerically simulated using the GEOWAVE software. The results indicate that the ~80 km wide Egyptian continental shelf protects the main part of the coastline from a slide-induced tsunami coming from the Rosetta area. An exception is the part of the coastline around Alexandria because focussing and shoaling processes can be simulated very close to the coast

Evolution of the Nile deep-sea turbidite system during the Late Quaternary: influence of climate change on fan sedimentation

International audienceThis paper presents an overview of the evolution of the Nile deep-sea turbidite system during the last 200 kyr, over a series of glacial to interglacial cycles. Six individual deep-sea fans were identified from an extensive field data set. Each fan comprises a canyon, channel system and terminal lobes. Two of these fan systems were possibly active at the same time, at least during some periods. Large-scale slope failures destroyed channel segments and caused the formation of new submarine fan systems. These slope failures thus played an important role in the overall evolution of the turbidite system. During the last glacial maximum (ca 25 to 14·8 ka) the central and eastern parts of the Nile deep-sea turbidite system were relatively inactive. This inactivity corresponds to a lowstand in sea-level, and a period of arid climate and relatively low sediment discharge from the Nile fluvial system. Rapid accumulation of fluvial flood-derived deposits occurred across the shallower part of the submarine delta during sea-level rise between ca 14·8 and 5 ka. The most recent deep-sea channel–lobe system was very active during this period of rising sea-level, which is also associated with a wetter continental climate and increased sediment and water discharge from the Nile. Increased sediment deposition in shallower water areas led to occasional large-scale slope failure. The Nile deep-sea turbidite system was largely inactive after ca 5 ka. This widespread inactivity is due to retreat of the coastline away from the continental shelf break, and to a more arid continental climate and reduced discharge of sediment from the Nile. The Nile deep-sea turbidite system may be more active during periods of rising and high sea-level associated with wetter climates, than during lowstands, and may rapidly become largely inactive during highstands in sea-level coupled with arid periods. These acute responses to climate change have produced sedimentary/stratigraphic features that diverge from traditional sequence models in their nature and timing. This large-scale sedimentary system responded to monsoon-driven climate change and sea-level change in a system-wide and contemporaneous manner

Lobe construction and sand/mud segregation by turbidity currents and debris flows on the western Nile deep-sea fan (Eastern Mediterranean)

International audienceBased on an unusual data set comprises bathymetric data, backscatter imagery, seismic-reflection and Chirp profiles, and sediment cores, the Late Quaternary lobe at the mouth of the youngest turbidite channel off the western Nile deep-sea fan was investigated. The large-scale construction of the lobe through time and space is mainly controlled by 1) a pre-existing topography inherited from the downslope movement of Messinian evaporites, and 2) the type and nature of gravity flows delivered to the basin floor. The margins of the lobe are defined by high-backscatter acoustic facies that contrasts strongly with the low-backscatter facies from the surrounding abyssal-plain deposits. Within the lobe, low-backscatter facies characterise the main channel-levee systems and lobate bodies immediately beyond the end of the channels. Cores reveal that the high-backscatter facies corresponds to a serie of extensive but thin debris-flow deposits with a fingered margin. These debrites comprise a muddy-sand matrix and dispersed clasts with diameter of 5 to 10 cm. The lower backscatter facies at channel mouths corresponds to alternations of thin sandy turbidites and muddy hemipelagites. Extensive thin debris flows therefore traversed surprisingly low gradients to reach the distal fringes of the lobe complex but are never found in the lobate bodies just beyond the channel mouths. Although the Nile deep-sea fan is considered as a silt/mud-rich accumulation, sand-prone deposits exist within the lobe. This sand/mud segregation results either from the presence of channelized features in the lobe and/or from the hydrodynamic process of particle transport by debris flows and turbulent flows

20,000 years of Nile River dynamics and environmental changes in the Nile catchment area as inferred from Nile upper continental slope sediments

International audienceMulti-proxy analysis of two marine sediment cores (MS27PT and MD04-2726) from the Nile continental slope provides evidence of changes in Nile sediment discharge related to changes in Ethiopian African Monsoon (EAM) precipitation, and allows us to reconstruct changes in Nile River runoff, vegetation and erosion in the Nile headwaters. Sediment element composition and neodymium isotopic composition reveal significant changes in clastic sediment provenance, with sources oscillating between a Saharan aeolian contribution during the Last Glacial Maximum/deglacial transition and during the Late Holocene, and a Blue/Atbara Nile fluvial contribution during the African Humid Period (AHP). This study provides a new understanding of past environmental changes. Between 14.6 and 14.13 ka there was a major input of sediments from the Ethiopian Highlands, consistent with a stronger EAM at that time. Climate in the Nile basin was wetter between 14.8 and 8.4 ka, with a corresponding increase in Blue Nile water and sediment discharge via the main Nile into the Eastern Mediterranean. The gradual climatic transition from the AHP to the present-day dry climate was reflected in a decrease in Blue Nile sediment deposition and flood discharge between 8.4 and 3.7 ka, with aridity at a maximum between 3.7 and 2.6 ka. The onset of drier conditions in the Blue Nile basin seems to have begun before the 8.2 ka cooling event in the North Atlantic. We speculate that the climatic change from the wet AHP to the dry late Holocene may have been a result of a break in the low latitude dynamic equilibrium between climate, vegetation and erosion, which may in turn have affected the climate in higher latitudes. Reduced Nile flow may also have had an impact on Levantine Intermediate Water originating in the Eastern Mediterranean through an increase in intermediate water formation