2,495 research outputs found

    Segmentally homologous neurons acquire two different terminal neuropeptidergic fates in the Drosophila nervous system

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    This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. In this study, we identify the means by which segmentally homologous neurons acquire different neuropeptide fates in Drosophila. Ventral abdominal (Va)-neurons in the A1 segment of the ventral nerve cord express DH31 and AstA neuropeptides (neuropeptidergic fate I) by virtue of Ubx activity, whereas the A2-A4 Va-neurons express the Capa neuropeptide (neuropeptidergic fate II) under the influence of abdA. These different fates are attained through segment-specific programs of neural subtype specification undergone by segmentally homologous neurons. This is an attractive alternative by which Hox genes can shape Drosophila segmental neural architecture (more sophisticated than the previously identified binary “to live” or “not to live” mechanism). These data refine our knowledge of the mechanisms involved in diversifying neuronal identity within the central nervous systemThis study was supported by grant number: BFU2013-43858-

    Magma Flow Rates and Temporal Evolution of the 2012–2014 Post‐Eruptive Intrusions at El Hierro, Canary Islands

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    The 2011–2014 volcanic activity at El Hierro (Canary Islands) was characterized by a 5‐month long submarine eruption as well as a series of magmatic intrusions occurring between 5 months and 2 years after the eruption, as revealed by seismic swarms and ground deformation. We study the temporal evolution of the six post‐eruptive magmatic intrusions, using Global Navigation Satellite System and Interferometric Synthetic Aperture Radar observations complemented with relocated earthquakes. Magma volumes and magma supply rates are determined from inversion of the geodetic data using a Bayesian approach. The intrusions last between ~3 and 20 days and are inferred to be sill‐like, thin compared with their lateral extent and emplaced in the ~13–16 km depth range. Initial magma flow rates of ~300 m3/s decay exponentially with time. The two largest intrusions occurred in June–July 2012 and March–April 2013. During each of these events, magma migrated laterally, and >120 ×106 m3 of magma was intruded beneath the island. The shortest events, <1 week‐long, intruded ~(24hyphen;44) ×106 m3 of magma beneath the volcano. We suggest that all intrusions originated from an overpressure in a deep magma body located beneath the center of El Hierro. The crust/mantle boundary and the previous intrusion that fed the 2011–2012 submarine eruption may have discouraged the ascent of the post‐eruptive intrusions to the surface and forced them to migrate laterally away from the island as sill‐like sources

    Introducing a personal learning environment in higher education. An analysis of connectivity.

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    Universities have a key role to play in the progress and development of the Knowledge Society. They should lead the way in the design of teaching strategies that promote knowledge building. Personal learning environments (PLE) represent a groundbreaking new development in educational practices through the incorporation of Information and Communications Technology (ICT), and an opportunity to promote the creation of universities without walls able to meet the demands of the knowledge society. This study focuses on the relationships established by the participants (students and teachers) in two higher education instructional sequences using institutionally-powered PLE (iPLE). One of the sequences was carried out at the University of Barcelona and the other at the University of Andorra. Both used the same technological support, the Elgg platform, which allows users to build their own personal work and learning environment. The main hypothesis of the study is that the relationships formed depend on the techno-pedagogical design of the teaching and learning process. The results show that in both cases the relationships that the participants establish with their peers and teachers are indeed related to the characteristics and requirements of the particular techno-pedagogical designs. Although the technological environment allowed all the participants to establish relationships with others, the main interactions were found in small working groups created to carry out learning and assessment activities. In conclusion, we stress the importance of planning teaching and learning activities and assessment processes that are able to exploit the full potential of PLE

    Introducing a personal learning environment in higher education. An analysis of connectivity

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    Universities have a key role to play in the progress and development of the Knowledge Society. They should lead the way in the design of teaching strategies that promote knowledge building. Personal learning environments (PLE) represent a groundbreaking new development in educational practices through the incorporation of Information and Communications Technology (ICT), and an opportunity to promote the creation of universities without walls able to meet the demands of the knowledge society.This study focuses on the relationships established by the participants (students and teachers) in two higher education instructional sequences using institutionally-powered PLE (iPLE). One of the sequences was carried out at the University of Barcelona and the other at the University of Andorra. Both used the same technological support, the Elgg platform, which allows users to build their own personal work and learning environment. The main hypothesis of the study is that the relationships formed depend on the techno-pedagogical design of the teaching and learning process.The results show that in both cases the relationships that the participants establish with their peers and teachers are indeed related to the characteristics and requirements of the particular techno-pedagogical designs. Although the technological environment allowed all the participants to establish relationships with others, the main interactions were found in small working groups created to carry out learning and assessment activities. In conclusion, we stress the importance of planning teaching and learning activities and assessment processes that are able to exploit the full potential of PLE

    Assessing the influence of isotopic composition of water on that of clay minerals during chemical treatments.

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    The isotopic composition of hydrogen in authigenic minerals is a useful tool to reconstruct past paleo-environments. Clay minerals are an important component of authigenic minerals in soils and sediments but they usually occur with other compounds that must be eliminated before the analysis, such as organic matter and carbonates. Thus, various “pre-treatments” are used, generally involving dilute HCl and H2O2 solutions in water. In this work, the influence of the isotopic composition of the water used in these pre-treatment solutions is assessed, using ten different samples of clay minerals. The isotopic composition of hydrogen was measured in each sample after HCl pre-treatment alone, H2O2 pre-treatment alone and both HCl and H2O2 pre-treatments in sequence, using two types of water in the pre-treatment solutions: one 2H-enriched and one 2H-depleted. The results indicate some influence of the isotopic composition of the water on the clay minerals after pre-treatment. In general, the samples showed significant alteration by HCl pre-treatment and negligible alteration by H2O2 pre-treatment. A pure kaolinite reference material did not show any change by chemical pre-treatment while a smectite reference material did show significant effects. Other samples (Ethiopian lacustrine sediment samples and Spanish cave sediments) showed important differences, which also depend on clay mineralogy. Thus, mineralogy seems to be the main cause of the variability in the alteration, especially the quantity of smectite. In addition, this result challenges the utility of clay minerals for isotope studies in acid conditions, such as in acidic soils, to reconstruct past environments and, therefore, climate changes.This study was developed during a stay supported by predoctoral mobility grant from the Spanish MINECO. Financial support for this work was obtained from MINECO Grant CGL2015-65387-C3-3-P. I. Campaña was the beneficiary of a predoctoral FPI Grant from the Spanish MINECO. We thank Jessica Wilson at the University of South Florida School of Geosciences who supported the isotopic analysis. J.G. Wynn was supported by an NSF IR/D program. Special thanks to the local resident of Burgos that help us remove the car from a mud puddle. // Funding for open access charge: Universidad de Málaga / CBU

    Surge glaciers during the Little Ice Age in the Pyrenees

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    Producción CientíficaLos complejos morrénicos históricos de los Pirineos contienen elementos de interés para conocer los cambios climáticos históricos y su evolución. La complejidad temporal que muestran permiten aproximarnos a la evolución y la dinámica de los glaciares durante la Pequeña Edad de Hielo (PEH). Además, la presencia de formas de modelado glaciar como crestas de compresión, morrenas hummocky y flutes señalan una dinámica glaciar definida por la presencia de flujos rápidos. La idea de este trabajo es mostrar la existencia de formas de modelado asociadas a flujos de hielo rápido o glaciares de oleada, así como su extensión, temporalidad y significado ambiental. Basados en el análisis de sistemas de formas glaciares (glacier landsystem), a partir de las huellas geomorfológicas como flutes, morrenas de empuje y morrenas hummocky en 17 complejos glaciares, se establece la existencia de flujos de hielo rápidos o glaciares de oleada durante la PEH. El análisis de morfosecuencias mediante trabajo de campo, fotointerpretación y fuentes históricas en 8 complejos morrénicos de la PEH y su comparación con reconstrucciones previas del clima en la Península Ibérica y Europa han permitido establecer como hipótesis una rápida respuesta de los glaciares a los breves cambios temporales de temperatura y humedad. Los circos glaciares con huellas de flujos rápidos se sitúan en los macizos más altos, siempre con las cumbres por encima de 3000 m, y están orientados prioritariamente al norte (88%). Los complejos morrénicos estudiados (Infierno Central, Infierno Oriental, Oulettes de Gaube, Monte Perdido, Marboré, La Paúl, Literola y Tempestades) están formados por cuatro unidades morfológicas principales: un sistema de morrenas frontales (U1); morrenas laterales o frontales más voluminosas (U2); complejos morrénicos menores con morrenas de empuje y hummocky que enlazan con flutes (U3); y arcos menores situados valle arriba (U4), no existentes en todos los casos. La Unidad 3 pertenece a una etapa con flujos rápidos del hielo o glaciares de oleada y a partir de la morfoestratigrafía se puede establecer que estos procesos se produjeron en torno a 1820-1840, en un lapso temporal de 20-35 años, ya al final de la PEH. Esta unidad la relacionamos con una posible respuesta climática a un enfriamiento repentino y al aumento de las precipitaciones invernales que incrementa la disponibilidad de agua de fusión nival y la rápida fusión del hielo durante el verano, generando rápidos cambios hidrodinámicos en los pequeños glaciaresMinisterio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (project CGL2015-68144-R

    Alcabala sales tax farmers in the district of Cuenca (1464-1470)

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    El siguiente trabajo versa sobre los personajes e instituciones que arrendaban las alcabalas de los sexmos de Cuenca entre 1464 y 1470. En este artículo lo que se pretende es dar a conocer a estos individuos, señalando su procedencia familiar, las rentas a las que solían pujar y la importancia de cada grupo socialIn this work, we study the tax-farmers and the institutions that leased the alcabala sales tax in the fiscal district of Cuenca between 1464 and 1470. This paper intends to create a social portrait of these men, focussing on their family origin, the rents for which they were to bid, and the importance each social group acquired in this fiel

    Prevalence of dementia and major dementia subtypes in Spanish populations: A reanalysis of dementia prevalence surveys, 1990-2008

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    Background This study describes the prevalence of dementia and major dementia subtypes in Spanish elderly. Methods We identified screening surveys, both published and unpublished, in Spanish populations, which fulfilled specific quality criteria and targeted prevalence of dementia in populations aged 70 years and above. Surveys covering 13 geographically different populations were selected (prevalence period: 1990-2008). Authors of original surveys provided methodological details of their studies through a systematic questionnaire and also raw age-specific data. Prevalence data were compared using direct adjustment and logistic regression. Results The reanalyzed study population (aged 70 year and above) was composed of Central and North-Eastern Spanish sub-populations obtained from 9 surveys and totaled 12,232 persons and 1,194 cases of dementia (707 of Alzheimer's disease, 238 of vascular dementia). Results showed high variation in age- and sex-specific prevalence across studies. The reanalyzed prevalence of dementia was significantly higher in women; increased with age, particularly for Alzheimer's disease; and displayed a significant geographical variation among men. Prevalence was lowest in surveys reporting participation below 85%, studies referred to urban-mixed populations and populations diagnosed by psychiatrists. Conclusion Prevalence of dementia and Alzheimer's disease in Central and North-Eastern Spain is higher in females, increases with age, and displays considerable geographic variation that may be method-related. People suffering from dementia and Alzheimer's disease in Spain may approach 600,000 and 400,000 respectively. However, existing studies may not be completely appropriate to infer prevalence of dementia and its subtypes in Spain until surveys in Southern Spain are conductedFinancial aid was obtained from the Spanish RECSP C03-09, CIEN C03-06 and CIBERNED networks, and from the Pfizer Foundation in particularS

    High-resolution patterns of palaeoenvironmental changes during the Little Ice Age and the Medieval Climate Anomaly in the northwestern Iberian Peninsula

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    ABSTRACT: A high resolution core (9.7 yr cm-1 ) from the Chao de Veiga Mol raised bog (NW Iberian Peninsula) was analyzed to identify plant macrofossils, estimate peat humification and calculate hydroclimatic indices based on current bog species, with the overall aim of determining the climate conditions associated with evolution of the bog during the Medieval Climate Anomaly and the Little Ice Age. These proxies, together with historical and climate data, proved to be good indicators of the changes in bog surface wetness. Analysis: of the core led to identification of 9 different periods: two corresponding to the so-called Medieval Climate Anomaly (930 to 1345 AD, 1075–665 calibrated years before present [cal. yr BP]); four corresponding to the Little Ice Age (1345 to 1905 AD; 665–105 cal yr BP); and three corresponding to the last century (1905 to 2000 AD). The findings revealed a generally dry climate that lasted until the 14th century, followed by a transition to a long period with a more humid, but characteristically very variable climate, which ended at the beginning of the 20th century and was followed by a rapid transition to more humid conditions and finally, a change to drier conditions. The Medieval Climate Anomaly was indicated by the abundance of dry-adapted mosses (Leucobryum glaucum, Hypnum cupressiforme) and characterized by warm dry conditions and high levels of peat humification, with alternating wet phases. The LIA period was dated by a large abundance of Sphagnum species (an indicator of wetness) and a gradual increase in the humification index. However, four different climate phases were differentiated in this period. High-resolution reconstruction of the evolution of the CVM bog and the multiproxy approach have together enabled a more detailed identification of climatic variations in this area, which are generally consistent with the global models, as well as better definition of the elusive climatic oscillations in the last millennium and confirmation of the importance of local modulation of global models. The study provides new information and a detailed chronology of climatic events that will help to refine local modulation of the climate evolution model in the still quite unexplored region of the NW Iberian Peninsula, a key area for understanding the paleoclimatic dynamics in SW Europe.This research was funded with the support of the Xunta de Galicia government (Spain) through projects INCITE09-200-019-PR and Consolidacion e Estructuracion 2018 GRC GI- 1243-GEMAP, ED431C 2018/32

    Repeated magmatic intrusions at El Hierro Island following the 2011–2012 submarine eruption

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    After more than 200 years of quiescence, in July 2011 an intense seismic swarm was detected beneath the center of El Hierro Island (Canary Islands), culminating on 10 October 2011 in a submarine eruption, 2 km off the southern coast. Although the eruption officially ended on 5 March 2012, magmatic activity continued in the area. From June 2012 to March 2014, six earthquake swarms, indicative of magmatic intrusions, were detected underneath the island. We have studied these post-eruption intrusive events using GPS and InSAR techniques to characterize the ground surface deformation produced by each of these intrusions, and to determine the optimal source parameters (geometry, location, depth, volume change). Source inversions provide insight into the depth of the intrusions (~ 11–16 km) and the volume change associated with each of them (between 0.02 and 0.13 km3). During this period, > 20 cm of uplift was detected in the central-western part of the island, corresponding to approximately 0.32–0.38 km3 of magma intruded beneath the volcano. We suggest that these intrusions result from deep magma migrating from the mantle, trapped at the mantle/lower crust discontinuity in the form of sill-like bodies. This study, using joint inversion of GPS and InSAR data in a post-eruption period, provides important insight into the characteristics of the magmatic plumbing system of El Hierro, an oceanic intraplate volcanic island
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