Restoration of Cymodocea nodosa (Uchria) Ascherson seagrass prairies through seed propagation. Germination in vitro, plantlet acclimation and transplanting to natural meadows.

[EN] The seagrass Cymodocea nodosa (Ucria) Ascherson is the most abundant seagrass species in the Canary Islands (Spain), where it forms dense submerged, ecologically relevant communities as stable and protected habitats. As with other seagrasses, concern has arisen due to a decline in the number and extension of the communities as the result of adverse activities in coastal areas. Seed germination and planting are assumed as cost-effective method for restoration. In the frame of the restoration of natural populations of Cymodocea nodosa, pilot experiences not tested so far in the Canary Islands have been carried out to developed in vitro techniques to produce viable seedlings and its transference to the natural environment.

On existence and uniqueness of positive solutions to a class of fractional boundary value problems

[EN] The purpose of this paper is to investigate the existence and uniqueness of positive solutions for the following fractional boundary value problem D 0 + α u ( t ) + f ( t , u ( t ) ) = 0 , 0 < t < 1 , u ( 0 ) = u ( 1 ) = u ′ ( 0 ) = 0 , where 2 < α ≤ 3 and D 0 + α is the Riemann-Liouville fractional derivative. Our analysis relies on a fixed-point theorem in partially ordered metric spaces. The autonomous case of this problem was studied in the paper [Zhao et al., Abs. Appl. Anal., to appear], but in Zhao et al. (to appear), the question of uniqueness of the solution is not treated. We also present some examples where we compare our results with the ones obtained in Zhao et al. (to appear). 2010 Mathematics Subject Classification: 34B15

A two-stage economic succession at the inception of farming in central Portugal. Preliminary examination of possible causes and consequences

[EN]Notwithstanding their scarcity and uneven distribution, zooarchaeological and stable isotope data sets on the Early and Middle Neolithic (5500–3200 cal BC) in the region of Estremadura in Central Portugal strongly suggest that two succeeding stages in subsistence strategies took place: sheep and goat itinerant pastoralism (across large areas) and/or renewed focus on wild food sources (cervid hunting, harvesting marine and freshwater food) which replaced livestock farming within smaller areas and less specialised hunting practices. This economic shift seems to have coincided with two other dramatic changes: the 5.9 kyr cal BP climate event and the onset of megalithism. Possible correlations between these past cultural and palaeoenvironmental phenomena are herein preliminarily outlined. [ES] A pesar de su escasez y distribución desigual, el conjunto de datos arqueozoológicos y de isótopos estables para el Neolítico Antiguo y Medio de la región de Estremadura en el centro de Portugal (5500-3200 a. C. cal), sugiere con claridad dos etapas sucesivas en las estrategias de subsistencia: pastoreo itinerante de ovejas y cabras (ocupando grandes territorios) y/o un renovado interés por los recursos alimenticios silvestres (caza de cérvidos, recolección de alimentos marinos y de agua dulce), que reemplazó otras formas de ganadería más confinadas en el espacio acciones con regímenes de mantenimiento reducidos y unas prácticas de caza menos especializadas. Este cambio económico parece haber ocurrido junto con otros dos cambios dramáticos, el evento climático 5.9 k BP (cal.) y el inicio del megalitismo. Aquí se esbozan de forma preliminar las posibles correlaciones entre estos fenómenos culturales y paleoambientales del pasado.