Las infraestructuras de recarga y el despegue del vehículo eléctrico.

Este trabajo revisa la evolución y estado actual de la automoción eléctrica; analiza las ventajas ambientales, de eficiencia energética y de costes del motor eléctrico frente al de combustión interna; y presenta como limitaciones para el uso del vehículo eléctrico, el desarrollo actual de las baterías recargables y la lenta implantación de electrolineras. Con el objetivo de contribuir al desarrollo de una actividad económica respetuosa con el medio ambiente y basada en nuevas tecnologías, se proyecta, a partir de experiencias previas, una instalación de puntos de recarga para una ciudad de 50.000 habitantes con un parque de 100 vehículos eléctricos que dispone de dos plazas de recarga rápida (poste trifásico 400V CA), siete plazas de recarga lenta (postes monofásicos 230V CA) y de 50 módulos fotovoltaicos que producen diariamente la energía equivalente a la recarga lenta de un vehículo en los meses fríos y de dos en los meses cálidos.

Triclabendazole-resistant Fasciola hepatica: β-tubulin and response to in vitro treatment with triclabendazole

Resistance in Fasciola hepatica to triclabendazole (Fasinex) has emerged in several countries. Benzimidazole resistance in parasitic nematodes has been linked to a single amino acid substitution (phenylalanine to tyrosine) at position 200 on the [beta]-tubulin molecule. Sequencing of [beta]-tubulin cDNAs from triclabendazole-susceptible and triclabendazole-resistant flukes revealed no amino acid differences between their respective primary amino acid sequences. In order to investigate the mechanism of triclabendazole resistance, triclabendazole-susceptible and triclabendazole-resistant flukes were incubated in vitro with triclabendazole sulphoxide (50 [mu]g/ml). Scanning and transmission electron microscopy revealed extensive damage to the tegument of triclabendazole-susceptible F. hepatica, whereas triclabendazole-resistant flukes showed only localized and relatively minor disruption of the tegument covering the spines. Immunocytochemical studies, using an anti-tubulin antibody, showed that tubulin organization was disrupted in the tegument of triclabendazole-susceptible flukes. No such disruption was evident in triclabendazole-resistant F. hepatica. The significance of these findings is discussed with regard to the mechanism of triclabendazole resistance in F. hepatica.

The uptake of silica during the spring bloom in the North East Atlantic Ocean

A full understanding of the biogeochemical cycling of silica in the North Atlantic is hampered by a lack of estimates of silica uptake by phytoplankton. We applied the ${}^{32}\text{Si}$ radiotracer incubation technique to determine silica uptake rates at 10 sites during the UK-(Natural Environment Research Council) Faroes-Iceland-Scotland hydrographic and environmental survey (FISHES) cruise in the Northeast Atlantic, May 2001. Column silica uptake rates ranged between 6 and 166 mmol Si $\text{m}^{-2}\ \text{d}^{-1}$; this data set was integrated with concurrent hydrographic, chemical, and primary productivity data to explain these changes in silica uptake in terms of the progress of the spring bloom. In order to interpret data covering a relatively large spatial and temporal scale, we used mean photic zone silica concentration as a proxy time-series measure of diatom bloom progression. Both absolute and specific silica uptake rates were highest at dissolved silica concentrations >2 mmol $\text{L}^{-1}$. Si and C uptake were vertically decoupled at those stations where surface silica was strongly depleted. Absolute primary productivity was not strongly correlated with dissolved silica concentrations, owing to either exhaustion of silica at diatom-dominated stations or to dominance of the community by other phytoplankton. Silica uptake as a function of increased substrate concentration was linear up to 25 $\mu \text{mol}\ \text{L}^{-1}$; we consider some possible reasons for the nonhyperbolic response.

Prograded Holocene beach-ridges with superimposed dunes in north-east Ireland: mechanisms and timescales of fine and coarse beach sediment decoupling and deposition

Two depositional models to account for Holocene gravel-dominated beach ridges covered by dunes, occurring on the northern coast of Ireland, are considered in the light of infrared-stimulated luminescence ages of sand units within beach ridges, and 14C ages from organic horizons in dunes. A new chronostratigraphy obtained from prograded beach ridges with covering dunes at Murlough, north-east Ireland, supports a model of mesoscale alternating sediment decoupling (ASD) on the upper beach, rather than macroscale sequential sediment sourcing to account for prograded beach ridges and covering dunes. The ASD model specifies storm or fair-weather sand beach ridges forming at high-tide positions (on an annual basis at minimum), which acted as deflationary sources for landward foredune development. Only a limited number of such late-Holocene beach ridges survive in the observed prograded series. Beach ridges only survive when capped by storm-generated gravel beaches that are deposited on a mesoscale time spacing of 50–130 years. The morphodynamic shift from a dissipative beach face for dune formation to a reflective beach face for gravel capping appears to be controlled by the beach sand volume falling to a level where reflective conditions can prevail. Sediment volume entering the beach is thought to have fluctuated as a function of a forced regression associated with the falling sea level from the mid-Holocene highstand (ca. 6000 cal. yr BP) identified in north-east Ireland. The prograded beach ridges dated at ca. 3000 to 2000 cal. yr BP indicate that the Holocene highstand’s regressive phase may have lasted longer than previously specified.