Efecto de la radiación ultravioleta sobre los ecosistemas acuáticos

Hasta hace poco tiempo se consideraba que la radiación ultravioleta carecía de importancia como factor ambiental en los ecosistemas acuáticos, ya que se suponía que se absorbía totalmente en los primeros centímetros de la columna de agua. Gracias al desarrollo de mejores instrumentos de medición, hoy se sabe que la penetración de la radiación ultravioleta en el agua es mucho mayor que la estimada anteriormente, y que sus efectos biológicos resultan observables hasta decenas de metros de profundidad. Este artículo de divulgación científica incluye, además de lecturas sugeridas, información del ozono estratosférico y troposférico, y sobre factores que afectan la intensidad de la radiación ultravioleta que llega a la superficie terrestre

Comparison of J-r test techniques under gaseous hydrogen environment

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Caracterización de las accesiones de cardo como materia prima para la producción de Biodiesel

La búsqueda de fuentes alternativas de energía renovables se incrementó en los últimos años debido al aumento del costo del petróleo y la necesidad de reducir la contaminación ambiental. El objetivo de este estudio fue caracterizar la composición química de la semilla de cardo (Cynara cardunculus L.), determinar su potencial como materia prima para la producción de biodiesel. Las muestras analizadas fueron accesiones de cardo cultivado (var. altilis) y silvestre (var. sylvestris), ambas molidas y secadas en estufa hasta peso constante y conservadas a -18°C hasta su caracterización. La determinación de proteínas se realizó por Kjeldahl (AOAC 936.15) obteniéndose valores entre 22.83% (silvestres) y 25.06% (cultivadas). El contenido de aceite fue de 20.80 ± 6.65%; determinado por Soxhlet (AOCS, 2009). Solo dos accesiones, mostraron un contenido de aceite destacado, 35.95% y 27.78%, respectivamente. La acidez varió de 0,68% a 3,57% de ácido oleico (IRAM 5512), mostrando diferencias entre muestras. La composición de ácidos grasos (IRAM 5651/09) fue similar para ambas variedades botánicas: palmítico (10.9%), esteárico (3.0%), oleico (23.5%), linoleico (61.3%). La comparación con los cultivos energéticos tradicionales (soja, girasol y colza) mostró que el perfil de ácidos grasos de cardo es similar a los obtenidos para la soja. Al estimar la influencia de la composición de la materia prima en las propiedades del biodiesel, las mismas presentan el grado insaturación bajo, lo mismo que la relación ácido oleico/linoleico en el aceite, mostrando indicadores acordes para su viabilidad para ser utilizado como biocombustible. El contenido de proteínas, (uso del expeller como alimento balanceado) resulta inferior a lo reportado para otras oleaginosas (30%, 32% y 44% para girasol, colza y soja respectivamente). La continuidad de este proyecto consiste en obtener el biodiesel a partir de aceite de cardo y su posterior análisis y estudiar el expeller para la elaboración de alimentos balanceados

Volatile profile of white wines fermented with sequential inoculation of Starmerella bacillaris and Saccharomyces cerevisiae

Mixed fermentations with Starmerella bacillaris and Saccharomyces cerevisiae affect the chemical composition of wines, by modulating various metabolites of oenological interest. The current study was carried out to elucidate the effect of sequential inoculation of the above mentioned species on the production of white wines, especially on the chemical and aromatic characteristics of Chardonnay, Muscat, Riesling and Sauvignon blanc wines. Titratable acidity and glycerol content exhibited evident differences among the wines after fermentation. For volatile compounds, mixed fermentations led to a reduction of the total esters, including ethyl acetate, which is a compound responsible for wine deterioration. However, Sauvignon blanc wines fermented by mixed cultures contained significantly higher levels of esters and thiols, both associated with positive sensory attributes. These findings suggest that sequential inoculations possess great potential in affecting and modulating the chemical and aromatic profile of white wines, especially those produced from Sauvignon blanc grapes

Multidimensional integration of RDF datasets

Data providers have been uploading RDF datasets on the web to aid researchers and analysts in finding insights. These datasets, made available by different data providers, contain common characteristics that enable their integration. However, since each provider has their own data dictionary, identifying common concepts is not trivial and we require costly and complex entity resolution and transformation rules to perform such integration. In this paper, we propose a novel method, that given a set of independent RDF datasets, provides a multidimensional interpretation of these datasets and integrates them based on a common multidimensional space (if any) identified. To do so, our method first identifies potential dimensional and factual data on the input datasets and performs entity resolution to merge common dimensional and factual concepts. As a result, we generate a common multidimensional space and identify each input dataset as a cuboid of the resulting lattice. With such output, we are able to exploit open data with OLAP operators in a richer fashion than dealing with them separately.This research has been funded by the European Commission through the Erasmus Mundus Joint Doctorate Information Technologies for Business Intelligence-Doctoral College (IT4BI-DC) program.Peer ReviewedPostprint (author's final draft

South America holds the greatest diversity of native daisies (Asteraceae) in the world: an updated catalogue supporting continental-scale conservation.

Abstract: Asteraceae is the world’s richest plant family and is found on all continents, in environments ranging from the coast to the highest mountains. The family shows all growth forms and, as in other angiosperm families, species richness is concentrated in tropical regions. South America has the highest diversity of Asteraceae in the world, yet taxonomic and distributional knowledge gaps remain. This study compiles an updated catalog of Asteraceae native to South America, based on national and regional checklists and ongoing large-scale flora projects. The resulting checklist includes a total of 6,940 species and 564 genera native to South America to date, which represent about a quarter of the family’s global diversity. Countries already considered to be megadiverse show the greatest diversity, such as Brazil with 2,095 species, followed by Peru (1,588), Argentina (1,377), and Colombia (1,244), with this diversity mainly focused on the Brazilian Highlands and the Andes. Species endemism also peaks in Brazil, but Sørensen distances reveal the Chilean flora to be eminently different from the rest of the continent. Tribes better represented in the continent are Eupatorieae, Senecioneae and Astereae, also with a remarkably presence of entirely South American subfamilies representing earliest diverging lineages of the Asteraceae, such as Barnadesioideae, Wunderlichioideae, Famatinanthoideae, and Stifftioideae. It is estimated that the discovery and description curves have not yet stabilized, and the number of species is likely to increase by 5 to 10% in the coming years, posing major challenges to continental-scale conservation

The CERN PS multi-turn extraction based on beam splittting in stable islands of transverse phase space: Design Report

Since 2001 considerable effort has been devoted to the study of a possible replacement of the continuous-transfer extraction mode from the PS to the SPS. Such an approach, called Multi-Turn Extraction (MTE), is based on capture of the beam inside stable islands of transverse phase space, generated by sextupoles and octupoles, thanks to a properly chosen tune variation. Both numerical simulations and measurements with beam were performed to understand the properties of this new extraction mode. The experimental study was completed at the end of 2004 and by the end of 2005 a scheme to implement this novel approach in the PS machine was defined and its performance assessed. This design report presents the outcome of the studies undertaken both in terms of technical issues as well as of resources necessary to implement the proposed scheme