Modelización de la estructura-toxicidad de diversos pesticidas utilizando métodos QSAR

La calidad de los recursos hídricos es quizás actualmente el tema más discutido en lo que respecta a la preservación del ambiente, ya que los ecosistemas acuáticos han sufrido cambios en todo el mundo en la mayoría de los casos irreversibles. Estos cambios se asocian a menudo con las actividades humanas como la deforestación, la liberación de efluentes industriales y domésticos, además el uso de pesticidas en los campos agrícolas, lo cual contribuye a la caída de la calidad de los recursos hídricos (Zvinavashe,2009). Los pesticidas son importantes para el sistema agrícola. Sin embargo, es crucial que se usen de manera adecuada a fin de preservar la calidad del producto final y los recursos naturales que apoyan su producción como lo son el suelo y el agua. Los pesticidas son productos cuya función es eliminar los daños que causan los organismos-plaga a los cultivos agrícolas garantizando así una alta productividad (Repetto, 2004). A pesar de que estas moléculas, cuando se aplican, tienen los organismos objetivo, como su destino final, el 99% de los pesticidas que se aplican van al aire, agua y suelo, es decir, solo el 1% llega a su destino. Este hallazgo es inquietante debido a que la población mundial crece lo que significa que el uso de pesticidas aumentará para satisfacer las necesidades mundiales de alimentos por lo cual los recursos naturales se mantendrán bajo una intensa amenaza de estas moléculas (Toropov,2010)

Housing system and welfare of buffalo (Bubalus bubalis) cows

Twenty-eight buffalo cows were used to evaluate the effect of housing system on a range of behavioural and physiological variables. Fourteen cows were group-housed in a loose open-sided barn with a concrete floor and 10 m2 per head as space allowance (group IS). Fourteen others were group-housed in a similar barn but they could also benefit from an outdoor yard with 500 m2 per head as space allowance, free access to potholes for wallowing and spontaneous vegetation (group TS). Animals were subjected to six sessions of instantaneous scan sampling at 10-day intervals. Behavioural variables were expressed as proportions of subjects observed in each category of posture and activity. Phytohaemagglutinin (PHA) was used to perform a skin test based on non-specific delayed type hypersensitivity, whereas 20 mg of ovalbumin were injected subcutaneously to evaluate humoral immune response. Blood samples for evaluation of cortisol concentration were collected immediately prior to exogenous porcine ACTH injection and 1, 2 and 4 h after. The metabolic status of the animals and milk production were also monitored. The proportion of idling animals was higher in group IS than in group TS (P< 0·001). More IS buffalo cows were observed eating at the manger than TS animals (P< 0·001). A higher proportion of TS animals were observed in the sun (P< 0·001). Grazing and bathing activities were recorded only for TS animals. Our findings suggest that buffalo cows kept in intensive conditions and having no access to ample yards and potholes may extend their periods of idling with negative effects on the state of welfare. Immune responses, metabolite concentrations and milk production were not affected by treatment, whereas cortisol levels were higher in IS animals (P< 0·05). The provision of a housing system similar to natural conditions was able to improve the welfare of buffalo cows as indicated by the expression of some species-specific natural behaviours. Such conditions were also associated with lower adrenal cortex response to ACTH injection, possibly as a consequence of the higher degree of initiative allowed to TS cows

Hydrothermal pressure-temperature control on CO2 emissions and seismicity at Campi Flegrei (Italy)

Fluids supplied by stored magma at depth are causal factors of volcanic unrest, as they can cause pressurization/heating of hydrothermal systems. However, evidence for links between hydrothermal pressurization, CO2 emission and volcano seismicity have remained elusive. Here, we use recent (2010−2020) observations at Campi Flegrei caldera (CFc) to show hydrothermal pressure, gas emission and seismicity at CFc share common source areas and well-matching temporal evolutions. We interpret the recent escalation in seismicity and surface gas emissions as caused by pressure-temperature increase at the top of a vertically elongated (0.3–2 km deep) gas front. Using mass (steam) balance considerations, we show hydrothermal pressurization is causing energy transfer from the fluids to the host rocks, ultimately triggering low magnitude earthquakes within a seismogenetic volume containing the hydrothermal system. This mechanism is probably common to other worldwide calderas in similar hydrothermal activity state

Climbing dunes deposits in sierra de Los Tarjados, La Rioja province, Argentina

Eolian climbing dunes found in the sierra de Los Tarjados (south of the La Rioja province> Argentina) are described in this paper. According to their morphology two mayor types of dunes have been recognized: 1) climbing dunes associated to ramp deposits, which can ascent the mountain front; and 2) climbing dunes do not related to ramps and where deflationary channel developed between the dune front and the cliff. Climbing dunes sands show finer mean grain-size, better sorting and lower skewness than associated sand sheet deposit