Lectura durandiana del imaginario nocturno en Combray de M. Proust: los símbolos de la inversión.

Sin resume

Application of endochronic densification law for designing vibroflotation soil improvement technique

The densification phenomenon in dry or completely drained sands is mainly due to the application of dynamic loading, like an earthquake or other kind of vibrations. This fact causes a reduction of voids volume and in a consequence the compaction of the soil. A finite element model, including the generalized endochronic densification law, formulated in cylindrical coordinates, has been developed for simulating the vibroflotation soil improvement technique the numerical model. Punctual dynamic loadings, like those occurring in vibroflotation treatment, are reproduced in the code. There are several other vibration-compacting soil improvement techniques which could be modelled like an axi-symmetric problem with this new approach, which includes absorbent boundary conditions (silent boundaries)

La Trilogía sobre 'Communication Activism': 'Communication for Social Change', 'Media and Performance Activism' y 'Struggling for Social Justice Amidst Difference'.

Nos encontramos ante una review particular ya que parte de la cita de una trilogía. La obra seleccionada, 'Communication Activism', está relacionada con el sentido y objetivo principal de la publicación que la alberga: reflejar intensamente todas las aportaciones que, desde el ámbito científico, trabajan por un cambio fundamentado en la búsqueda de una justicia social universal

L´individu et la religion dans Oedipe d´André Gide.

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Germination and emergence of annual species and burial depth: Implications for restoration ecology

Due to the high content of viable seeds, topsoil is usually spread on ground left bare during railway and motorway construction to facilitate the regeneration of vegetation cover. However, during handling of the topsoil, seeds are often buried deeply and they cannot germinate or the seedlings cannot emerge from depth. This study experimentally explores the predictive value of seed mass for seed germination, mortality and seedling emergence at different burial depths for 13 common annual species in semiarid Mediterranean environments. We separate the effect of burial depth on germination and emergence by means of two experiments. In the germination experiment, five replicates of 20 seeds for each species were buried at depths ranging from 0 to 4 cm under greenhouse conditions. Germinated and empty or rotten seeds were counted after 8 weeks. In the emergence experiment, five replicates of four newly-germinated seeds per species were buried at the same depths under controlled conditions and emergence was recorded after 3 weeks. The effect of burial depth on percentage of germination and seedling emergence was dependent on seed size. Although all species showed a decrease in germination with burial depth, this decrease was greater for small-than large-seeded species. Percentage of emergence was positively related to seed mass but negatively related to burial depth. Seed mortality was higher for small-than large-seeded species, but there was no general effect of burial depth on this variable. Thus, the current practice of spreading 30 cm deep layers of topsoil in post-construction restoration projects is unadvisable. In this restoration scenario, thinner layers of topsoil should be used to achieve the maximum potential of the topsoil for germination and seedling establishmentFinancial support was received from the Spanish Ministry of Science and Innovation (Projects CGL2011-24871 and CGL2014-53789-R), the Madrid Regional Government (Project REMEDINAL3-P2013/MAE2719

Recursos sobre Educación: para el Desarrollo en internet

Peer Reviewe

Fungal-mediated mortality explains the different effects of dung leachates on the germination response of grazing increaser and decreaser species

Depending on their response to grazing, grassland species can be categorized as grazing increasers or decreasers. Grazing by livestock includes several different activities that can impact species differently. Recent evidence suggest that one of these actions, dung deposition, can reduce the germinative performance of decreaser species, thus favouring increasers. The present study tested the hypothesis that decreased germinative success of decreaser species is caused by a greater activity of fungal pathogens under the influence of dung leachates. We performed a phytotron experiment analysing the germination and fungal infections of fourteen species from Mediterranean grasslands. Species were grouped into phylogenetically-related pairs, composed of an increaser and a decreaser species. Seeds of each species were germinated under four different treatments (control, dung leachate addition, fungicide addition and dung leachate and fungicide addition), and the differences in germination percentage, germination speed and infection rate between each increaser species and its decreaser counterpart were analysed. Decreaser species were more affected by mortality than increaser ones, and these differences were higher under the presence of dung leachates. The differences in germinative performance after excluding the effect of seed mortality did not differ between treatments, showing that the main mechanism by which dung leachates favour increaser species is through increased mortality of the seeds of decreaser species. Drastic reductions in the number of dead seeds in the treatments including fungicide addition further revealed that fungal pathogens are responsible for these differences between species with different grazing response. The different vulnerabilities of increaser and decreaser species to the increased activity of fungal pathogens under the presence of dung leachates seems the main reason behind the differential effect of these leachates on species with different grazing responseFinancial support was received from the Spanish MINECO (Project CGL2014- 53789-R) and the Madrid Regional Government (Project REMEDINAL3). CPC was supported by a Marie Curie Intra-European Fellowship within the 7th European Community Framework Programme (TANDEM; project id. 626392

Dissecting the effects of simulated cattle activity on floristic composition and functional traits in Mediterranean grasslands

Livestock exerts direct and indirect effects on plant communities, changing colonization and extinction rates of species and the surrounding environmental conditions. There is scarce knowledge on how and to what extent these effects control the floristic and functional composition of plant communities in grasslands. We performed an experiment that included several treatments simulating trampling, defoliation, faeces addition and their combinations in a Mediterranean scrub community grazing-abandoned for at least 50 years. We monitored the plots for four years, and collected data on species composition, photosynthetically active radiation (PAR) and red:far-red ratio (R:FR), soil moisture and compaction. We estimated community weighted means (CWM) for height, habit, life cycle, seed mass and SLA. Neither compaction nor soil moisture were modified by the treatments, while PAR and R:FR increased in all treatments in comparison to the Control and Faeces treatments. The floristic composition of all treatments, except for Faeces, converged over time, but deviated from that of the Control. The functional traits displayed the trends expected in the presence of grazing: loss of erect species and increased cover of short species with light seeds, with rosettes and prostrate habit. However, contrary to the results in literature, SLA was lower in all the treatments than Control plots. Like the results for floristic composition, all treatments except for Faeces converged towards a similar functional composition at the end of the four year period. The results of this study show the initial evolution of a Mediterranean plant community in the presence of grazing, driven primarily by the destructive action of livestock. These actions seem to directly affect the rates of extinction/colonization, and indirectly affect the light environment but not the soil conditions. However, their effects on floristic and trait composition do not seem to differ, at least at the small spatio-temporal scaleFinancial support was provided by the Spanish Ministry of Education and Science (CGL2007-63382, CGL2011-24871, FPI scholarship BES-2004-4396 for Iker Dobarro and FPI scholarship BES- 2008-009821 for C.P. Carmona), the Programa de Actividades de I+D de la Comunidad de Madrid (Consejería de Educación, Comunidad Autónoma de Madrid, Spain) REMEDINAL-CM (S-0505/AMB/000335, S-2009/AMB/1783) and the REMEDINAL2 Programme (S- 2009/AMB/1783), supported by the Comunidad de Madrid and the European Social Fun