Alkenone analyses of sediment cores from the western Arabian Sea

Records of total organic carbon (TOC) and C37 alkenones were used as indicators for past primary productivity in the western and eastern Arabian Sea. Data from GeoB 3005, an open ocean site in the western Arabian Sea upwelling area, are compared with similar records of GeoB 3007 from the Owen Ridge, Ocean Drilling Program (ODP) Site 723 from the continental margin off Oman and MD 900963 from the eastern Arabian Sea. TOC/C37 alkenone records together with other proxies used to reconstruct upwelling intensity, indicate periods of high productivity in tune with precessional forcing all over the Arabian Sea. Based on their phase-relationship to variations in boreal summer insolation they can be divided into three groups. In the western Arabian Sea the precession-related phasing is different between productivity proxies and those for summer monsoon wind strength and upwelling intensity. TOC and C37 alkenone records from the western Arabian Sea lag the other monsoonal indicators by about 5 kyr, but lead productivity indicators from the eastern Arabian Sea by 3 kyr. Based on the differences in phase relationships associated with the precessional cycling between productivity and monsoonal proxies in the western Arabian Sea it is proposed that the TOC/C37 alkenone signal in the western Arabian Sea document a combined signal of moderate SW monsoon winds and of strengthened and prolonged NE monsoon winds. In the eastern Arabian Sea the phasing hints to coincidence between maximum productivity and stronger NE monsoon winds associated with precession-related maxima in ice volume. In contrast, variations in paleoproductivity at site GeoB 3007 from the Owen Ridge indicate productivity maxima during glacial substages 8.2, 6.2 and 2.2, whereas precessionrelated changes are of only minor importance at this location. The results of frequency analyses confirm that productivity at site GeoB 3007 responds predominantly to glacialinterglacial climate changes, while site GeoB 3005 from the open ocean upwelling region near the Gulf of Aden is dominated by precessional insolation. A possible explanation for the pattern revealed at the Owen Ridge is the periodic NW-SE displacement of the Findlater Jet axis, which separates the region of open ocean upwelling to the northwest from downwelling to the southeast ofthe jet. The carbon isotopes of planktic foraminifera reflect nutrient related d13C variations of dissolved inorganic carbon. The difference between the planktic foraminifera Globigerinoides ruber (w), living in the upper 50 m of the water column, and the deeper Iiving Neogloboquadrina dutertrei (Delta d13Cr-d) of core GeoB 3005 displays nutrient variations in the upwelling area near the Gulf of Aden. The results of cross-spectral analyses between Deltad13Cr-d of GeoB 3005 and proxies for SW monsoon intensity indicate, too, a dissociation of productivity from monsoonal upwelling intensity. Instead, productivity depends mainly on the availability of nutrients, while upwelling intensity of sub-surface water masses seems to be of only secondary importance. Additionally, sea surface temperatures (SSTs) were reconstructed using the unsaturation ratio of C37 alkenones. Alkenone SSTs reflect annual mean temperatures rather than explicitly the season of upwelling. This is evident from alkenone SSTs in a transect of surface sediments extending from the inner Gulf of Aden into the western Arabian Sea. The alkenone-derived SST records of GeoB 3005 from the open ocean upwelling region near the Gulf of Aden and GeoB 3007 from the Owen Ridge reveal similar variations with high SSTs during interglacial and low SSTs during glacial periods. The glacial marine oxygen isotope stage (MIS) 6 remains relatively warm and was not as cold as MIS 3 to 4 and 8 according to the alkenone SST. Similar variation-patterns were reconstructed in the coastal upwelling area off Oman for ODP Site 723 as weIl as in the eastern Arabian Sea for MD 900963, where upwelling is not as pronounced as in the western Arabian Sea. Spectral-analyses indicate that SST changes are in good agreement with the modulation of low-latitude precessional insolation changes by eccentricity. However, they do not show the pronounced cydicity in the precessional frequency band, which is characteristic for variations in paleoproductivity. Although the overall variation pattern is very similar, a dose comparison between the western (GeoB 3005) and the eastern Arabian Sea (MD 900963) shows larger differences between both sites during cold intervals than during periods of warm SSTs. This is attributed to a more effective cooling of surface waters in the western Arabian Sea by prolonged NE monsoon winds during times of expanded Northern Hemisphere ice-sheets, thereby lowering the annual mean SSTs stronger than in the eastern Arabian Sea.

Radiative properties for warm and hot dense matter

We will present calculations of opacities for matter under LTE conditions. Opacities are needed in radiation transport codes to study processes like Inertial Confinement Fusion and plasma amplifiers in X-ray secondary sources. For the calculations we use the code BiGBART, with either a hydrogenic approximation with j-splitting or self-consistent data generated with the atomic physics code FAC. We calculate the atomic structure, oscillator strengths, radiative transition energies, including UTA computations, and photoionization cross-sections. A DCA model determines the configurations considered in the computation of the opacities. The opacities obtained with these two models are compared with experimental measurements.

Equation of State and Opacities for Warm Dense Matter.

We will present recent developments in the calculation of opacity and equation of state tables suitable for including in the radiation hydrodynamic code ARWEN [1] to study processes like ICF or X-ray secondary sources. For these calculations we use the code BiG BART to compute opacities in LTE conditions, with self-consistent data generated with the Flexible Atomic Code (FAC) [2]. Non-LTE effects are approximately taken into account by means of the improved RADIOM model [3], which makes use of existing LTE data tables. We use the screened-hydrogenic model [4] to derive the Equation of State using the population and energy of the levels avaliable from the atomic data

Spatial distribution of the soil carbon pool in a Holm oak dehesa in Spain

Aims Dehesas are agroforestry systems characterized by scattered trees among pastures, crops and/or fallows. A study at a Spanish dehesa has been carried out to estimate the spatial distribution of the soil organic carbon stock and to assess the influence of the tree cover. Methods The soil organic carbon stock was estimated from the five uppermost cm of themineral soil with high spatial resolution at two plots with different grazing intensities. The Universal Kriging technique was used to assess the spatial distribution of the soil organic carbon stocks, using tree coverage within a buffering area as an auxiliary variable. Results A significant positive correlation between tree presence and soil organic carbon stocks up to distances of around 8 m from the trees was found. The tree crown cover within a buffer up to a distance similar to the crown radius around the point absorbed 30 % of the variance in the model for both grazing intensities, but residual variance showed stronger spatial autocorrelation under regular grazing conditions. Conclusions Tree cover increases soil organic carbon stocks, and can be satisfactorily estimated by means of crown parameters. However, other factors are involved in the spatial pattern of the soil organic carbon distribution. Livestock plays an interactive role together with tree presence in soil organic carbon distribution.

Instability and topology bifurcations on a hemisphere-cylinder at high angle of attack

La configuración de un cilindro acoplado a una semi-esfera, conocida como ’hemispherecylinder’, se considera como un modelo simplificado para numerosas aplicaciones industriales tales como fuselaje de aviones o submarinos. Por tanto, el estudio y entendimiento de los fenómenos fluidos que ocurren alrededor de dicha geometría presenta gran interés. En esta tesis se muestra la investigación del origen y evolución de los, ya conocidos, patrones de flujo (burbuja de separación, vórtices ’horn’ y vórtices ’leeward’) que se dan en esta geometría bajo condiciones de flujo separado. Para ello se han llevado a cabo simulaciones numéricas (DNS) y ensayos experimentales usando la técnica de Particle Image Velocimetry (PIV), para una variedad de números de Reynolds (Re) y ángulos de ataque (AoA). Se ha aplicado sobre los resultados numéricos la teoría de puntos críticos obteniendo, por primera vez para esta geometría, un diagrama de bifurcaciones que clasifica los diferentes regímenes topológicos en función del número de Reynolds y del ángulo de ataque. Se ha llevado a cabo una caracterización completa sobre el origen y la evolución de los patrones estructurales característicos del cuerpo estudiado. Puntos críticos de superficie y líneas de corriente tridimensionales han ayudado a describir el origen y la evolución de las principales estructuras presentes en el flujo hasta alcanzar un estado de estabilidad desde el punto de vista topológico. Este estado se asocia con el patrón de los vórtices ’horn’, definido por una topología característica que se encuentra en un rango de números de Reynolds muy amplio y en regímenes compresibles e incompresibles. Por otro lado, con el objeto de determinar las estructuras presentes en el flujo y sus frecuencias asociadas, se han usado distintas técnicas de análisis: Proper Orthogonal Decomposition (POD), Dynamic Mode Decomposition (DMD) y análisis de Fourier. Dichas técnicas se han aplicado sobre los datos experimentales y numéricos, demostrándose la buena concordancia entre ambos resultados. Finalmente, se ha encontrado en ambos casos, una frecuencia dominante asociada con una inestabilidad de los vórtices ’leeward’. ABSTRACT The hemisphere-cylinder may be considered as a simplified model for several geometries found in industrial applications such as aircrafts’ fuselages or submarines. Understanding the complex flow phenomena that surrounds this particular geometry is therefore of major industrial interest. This thesis presents an investigation of the origin and evolution of the complex flow pattern; i.e. separation bubbles, horn vortices and leeward vortices, around the hemisphere-cylinder under separated flow conditions. To this aim, threedimensional Direct Numerical Simulations (DNS) and experimental tests, using Particle Image Velocimetry (PIV) techniques, have been performed for a variety of Reynolds numbers (Re) and angles of attack (AoA). Critical point theory has been applied to the numerical simulations to provide, for the first time for this geometry, a bifurcation diagram that classifies the different flow topology regimes as a function of the Reynolds number and the angle of attack. A complete characterization about the origin and evolution of the complex structural patterns of this geometry has been put in evidence. Surface critical points and surface and volume streamlines were able to describe the main flow structures and their strong dependence with the flow conditions up to reach the structurally stable state. This state was associated with the pattern of the horn vortices, found on ranges from low to high Reynolds numbers and from incompressible to compressible regimes. In addition, different structural analysis techniques have been employed: Proper Orthogonal Decomposition (POD), Dynamic Mode Decomposition (DMD) and Fourier analysis. These techniques have been applied to the experimental and numerical data to extract flow structure information (i.e. modes and frequencies). Experimental and numerical modes are shown to be in good agreement. A dominant frequency associated with an instability of the leeward vortices has been identified in both, experimental and numerical results.

The contribution of two common shrub species to aboveground and belowgraound carbon pool in Iberian Dehesas

Shrubs play an important role in water-limited agro-silvo-pastoral systems by providing shelter and forage for livestock, for erosion control, to maintain biodiversity, diversifying the landscape, and above all, facilitating the regeneration of trees. Furthermore, the carbon sink capacity of shrubs could also help to mitigate the effects of climate change since they constitute a high proportion of total plant biomass. The contribution of two common extensive native shrub species (Cistus ladanifer L. and Retama sphaerocarpa (L.) Boiss.) to the carbon pool of Iberian dehesas (Mediterranean agro-silvo-pastoral systems) is analyzed through biomass models developed at both individual (biovolume depending) and community level (height and cover depending). The total amount of carbon stored in these shrubs, including above- and belowground biomass, ranges from 1.8 to 11.2 Mg C ha_1 (mean 6.8 Mg C ha_1) for communities of C. ladanifer and from 2.6 to 8.6 Mg C ha_1 (mean 4.5 Mg C ha_1) for R. sphaerocarpa. These quantities account for over 20e30% of the total plant biomass in the system. The potential for carbon sequestration of these shrubs in the studied system ranges 0.10e1.32 Mg C ha_1 year_1 and 0.25e1.25 Mg C ha_1 year_1 for the C. ladanifer and R. sphaerocarpa communities’ respectively

Effects of irrigation and time of application on the yield and quality of cv. Cabernet sauvignon in a warm climate

Mediterranean climate is characterized by hot summer, high evapotranspiration rates, and scarce precipitations (400 mm per year) during grapevine cycle. These extremely dry conditions affect vineyard productivity and sustainability. Supplementary irrigation is a needed practice in order to maintain yield and quality. Almost all Spanish grape growing regions are characterized by these within this context, especially in the center region, where this study was performed. The main objective of this work was to study the influence of irrigation on yield and quality. For this aim, we applied different levels of irrigation (mm of water applied) during different stages of growth and berry maturity. Four experimental treatments were applied considering the amount of water and the moment of the application: T1: Water irrigation (420 mm) applied from bloom to maturity. T2: Corresponded to the traditional irrigation scheduling, from preveraison to maturity (154 mm). T3: Water irrigation from bloom to preveraison, and water deficit from veraison to maturity (312 mm). T4: Irrigation applied from preveraison to maturity (230 mm) Experimental vineyard, cv. Cabernet Sauvignon, was located in a commercial vineyard (Bodegas Licinia S.L.) in the hot region of Morata de Tajuña (Madrid). The trial was performed during 2010 and 2011 seasons. Our results showed that yield increased from 2010 to 2011 in the treatments with a higher amount of water appli ed, T1 and T3 (24 and 10 % of yield increase respectively). This was mainly due to an increase in bud fertility (nº of bunches per shoot). Furthermore, sugar content was higher in T3 (27.3 ºBrix), followed by T2 (27 ºBrix). By contrast, T4 (irrigation from veraison) presented the lowest solid soluble concentration and the highest acidity. These results suggest that grapevine has an intrinsic capacity to adapt to its environment. However, this adaptation capacity should be evaluated considering the sensibility of quality parameters during the maturity period (acidity, pH, aroma, color...) and its impact on yield. Here, we demonstrated that a higher amount of water irrigation applied was no linked to a negative effect on quality.

Study of the effect of four warm mix asphalt additives on bitumen modified with 15% crumb rubber

Due to a growing concern over global warming, the bituminous mixture industry is making a constant effort to diminish its emissions by reducing manufacturing and installation temperatures without compromising the mechanical properties of the bituminous mixtures. The use of mixtures with tyre rubber has demonstrated that these mixtures can be economical and ecological and that they improve the behaviour of the pavements. However, bituminous mixtures with a high rubber content present one major drawback: they require higher mixing and installation temperatures due to the elevated viscosity caused by the high rubber content and thus they produce larger amounts of greenhouse gas emissions than conventional bituminous mixtures. This article presents a study of the effect of four viscosity-reducing additives (Sasobit®, Asphaltan A®, Asphaltan B® and Licomont BS 100®) on a bitumen modified with 15% rubber. The results of this study indicate that these additives successfully reduce viscosity, increase the softening temperature and reduce penetration. However, they do not have a clear effect on the test for elastic recovery and ductility at 25 °C.

Asphalt rubber mixtures with warm mix asphalt additives

En los últimos años, debido a la creciente preocupación por el calentamiento global y el cambio climático, uno de los retos más importantes a los que se enfrenta nuestra sociedad es el uso eficiente y económico de energía así como la necesidad correspondiente de reducir los gases de efecto invernadero (GEI). Las tecnologías de mezclas semicalientes se han convertido en un nuevo e importante tema de investigación en el campo de los materiales para pavimentos ya que ofrece una solución potencial para la reducción del consumo energético y las emisiones de GEI durante la producción y puesta en obra de las mezclas bituminosas. Por otro lado, los pavimentos que contienen polvo de caucho procedente de neumático fuera de uso, al hacer uso productos de desecho, ahorran energía y recursos naturales. Estos pavimentos ofrecen una resistencia mejorada a la formación de roderas, a la fatiga y a la fisuración térmica, reducen los costes de mantenimiento y el ruido del tráfico así como prolongan la vida útil del pavimento. Sin embargo, estas mezclas presentan un importante inconveniente: la temperatura de fabricación se debe aumentar en comparación con las mezclas asfálticas convencionales, ya que la incorporación de caucho aumenta la viscosidad del ligante y, por lo tanto, se producen mayores cantidades de emisiones de GEI. En la presente Tesis, la tecnología de mezclas semicalientes con aditivos orgánicos (Sasobit, Asphaltan A, Asphaltan B, Licomont) se incorporó a la de betunes de alta viscosidad modificados con caucho (15% y 20% de caucho) con la finalidad de dar una solución a los inconvenientes de mezclas con caucho gracias a la utilización de aditivos reductores de la viscosidad. Para este fin, se estudió si sería posible obtener una producción más sostenible de mezclas con betunes de alto contenido en caucho sin afectar significativamente su nivel de rendimiento mecánico. La metodología aplicada para evaluar y comparar las características de las mezclas consistió en la realización de una serie de ensayos de laboratorio para betunes y mezclas con caucho y con aditivos de mezclas semicalientes y de un análisis del ciclo de vida híbrido de la producción de mezclas semicalientes teniendo en cuenta la papel del aditivo en la cadena de suministro con el fin de cuantificar con precisión los beneficios de esta tecnología. Los resultados del estudio indicaron que la incorporación de los aditivos permite reducir la viscosidad de los ligantes y, en consecuencia, las temperaturas de producción y de compactación de las mezclas. Por otro lado, aunque la adición de caucho mejoró significativamente el comportamiento mecánico de los ligantes a baja temperatura reduciendo la susceptibilidad al fenómeno de fisuración térmica, la adición de las ceras aumentó ligeramente la rigidez. Los resultados del estudio reológico mostraron que la adición de porcentajes crecientes de caucho mejoraban la resistencia del pavimento con respecto a la resistencia a la deformación permanente a altas temperaturas y a la fisuración térmica a bajas temperaturas. Además, se observó que los aditivos mejoran la resistencia a roderas y la elasticidad del pavimento al aumentar el módulo complejo a altas temperaturas y al disminuir del ángulo de fase. Por otra parte, el estudio reológico confirmó que los aditivos estudiados aumentan ligeramente la rigidez a bajas temperaturas. Los ensayos de fluencia llevados a cabo con el reómetro demostraron una vez más la mejora en la elasticidad y en la resistencia a la deformación permanente dada por la adición de las ceras. El estudio de mezclas con caucho y aditivos de mezclas semicalientes llevado a cabo demostró que las temperaturas de producción/compactación se pueden disminuir, que las mezclas no experimentarían escurrimiento, que los aditivos no cambian significativamente la resistencia conservada y que cumplen la sensibilidad al agua exigida. Además, los aditivos aumentaron el módulo de rigidez en algunos casos y mejoraron significativamente la resistencia a la deformación permanente. Asimismo, a excepción de uno de los aditivos, las mezclas con ceras tenían la misma o mayor resistencia a la fatiga en comparación con la mezcla control. Los resultados del análisis de ciclo de vida híbrido mostraron que la tecnología de mezclas semicalientes es capaz de ahorrar significativamente energía y reducir las emisiones de GEI, hasta un 18% y 20% respectivamente, en comparación con las mezclas de control. Sin embargo, en algunos de los casos estudiados, debido a la presencia de la cera, la temperatura de fabricación debe reducirse en un promedio de 8 ºC antes de que los beneficios de la reducción de emisiones y el consumo de combustible puedan ser obtenidos. Los principales sectores contribuyentes a los impactos ambientales generados en la fabricación de mezclas semicalientes fueron el sector de los combustibles, el de la minería y el de la construcción. Due to growing concerns over global warming and climate change in recent years, one of the most important challenges facing our society is the efficient and economic use of energy, and with it, the corresponding need to reduce greenhouse gas (GHG) emissions. The Warm Mix Asphalt (WMA) technology has become an important new research topic in the field of pavement materials as it offers a potential solution for the reduction of energy consumption and GHG emissions during the production and placement of asphalt mixtures. On the other hand, pavements containing crumb-rubber modified (CRM) binders save energy and natural resources by making use of waste products. These pavements offer an improved resistance to rutting, fatigue and thermal cracking; reduce traffic noise and maintenance costs and prolong pavement life. These mixtures, however, present one major drawback: the manufacturing temperature is higher compared to conventional asphalt mixtures as the rubber lends greater viscosity to the binder and, therefore, larger amounts of GHG emissions are produced. In this dissertation the WMA technology with organic additives (Sasobit, Asphaltan A, Asphaltan B and Licomont) was applied to CRM binders (15% and 20% of rubber) in order to offer a solution to the drawbacks of asphalt rubber (AR) mixtures thanks to the use of fluidifying additives. For this purpose, this study sought to determine if a more sustainable production of AR mixtures could be obtained without significantly affecting their level of mechanical performance. The methodology applied in order to evaluate and compare the performance of the mixtures consisted of carrying out several laboratory tests for the CRM binders and AR mixtures with WMA additives (AR-WMA mixtures) and a hybrid input-output-based life cycle assessment (hLCA) of the production of WMA. The results of the study indicated that the incorporation of the organic additives were able to reduce the viscosity of the binders and, consequently, the production and compaction temperatures. On the other hand, although the addition of rubber significantly improved the mechanical behaviour of the binders at low temperatures reducing the susceptibility to thermal cracking phenomena, the addition of the waxes slightly increased the stiffness. Master curves showed that the addition of increasing percentages of rubber improved the resistance of the pavement regarding both resistance to permanent deformation at high temperatures and thermal cracking at low temperatures. In addition, the waxes improved the rutting resistance and the elasticity as they increased the complex modulus at high temperatures and decreased the phase angle. Moreover, master curves also attest that the WMA additives studied increase the stiffness at low temperatures. The creep tests carried out proved once again the improvement in the elasticity and in the resistance to permanent deformation given by the addition of the waxes. The AR-WMA mixtures studied have shown that the production/compaction temperatures can be decreased, that the mixtures would not experience binder drainage, that the additives did not significantly change the retained resistance and fulfilled the water sensitivity required. Furthermore, the additives increased the stiffness modulus in some cases and significantly improved the permanent deformation resistance. Except for one of the additives, the waxes had the same or higher fatigue resistance compared to the control mixture. The results of the hLCA demonstrated that the WMA technology is able to significantly save energy and reduce GHG emissions, up to 18% and 20%, respectively, compared to the control mixtures. However, in some of the case studies, due to the presence of wax, the manufacturing temperature at the asphalt plant must be reduced by an average of 8ºC before the benefits of reduced emissions and fuel usage can be obtained. The results regarding the overall impacts generated using a detailed production layer decomposition indicated that fuel, mining and construction sectors are the main contributors to the environmental impacts of manufacturing WMA mixtures.

Male fitness increases when females are eliminated from gene pool: Implications for the Y chromosome

Because the two sexes share a common gene pool while performing many different biological functions, mutations benefiting one sex may not accumulate due to counter selection in the other sex. In these experiments 99% of a haploid genome of Drosophila melanogaster was constrained to segregate like a male-limited Y chromosome for 41 generations, thereby eliminating potential counter selection in females. The synthetic Y chromosomes rapidly accumulated genetic variation that increased male fitness and decreased female fitness. The survival and fertility of females declined when they were mated to males expressing the synthetic Y chromosomes. These results suggests that opposing selection between the sexes may substantially interfere with sex-specific adaptation. They also demonstrate how intersexual evolutionary conflict can lead to perpetual degeneration of the Y via genetic hitchhiking of deleterious mutations.

Keeping Mars warm with new super greenhouse gases

Our selection of new super greenhouse gases to fill a putative “window” in a future Martian atmosphere relies on quantum-mechanical calculations. Our study indicates that if Mars could somehow acquire an Earth-like atmospheric composition and surface pressure, then an Earth-like temperature could be sustained by a mixture of five to seven fluorine compounds. Martian mining requirements for replenishing the fluorine could be comparable to current terrestrial extraction.