Winnerless competition in coupled Lotka-Volterra maps

Winnerless competition is analyzed in coupled maps with discrete temporal evolution of the Lotka-Volterra type of arbitrary dimension. Necessary and sufficient conditions for the appearance of structurally stable heteroclinic cycles as a function of the model parameters are deduced. It is shown that under such conditions winnerless competition dynamics is fully exhibited. Based on these conditions different cases characterizing low, intermediate, and high dimensions are therefore computationally recreated. An analytical expression for the residence times valid in the N-dimensional case is deduced and successfully compared with the simulations.J.L.C. and E.D.G. acknowledge support from IVIC-141, L.A.G.-D. acknowledges support from IVIC-1089 and P.V. acknowledges support from MINECO TIN2012-30883

Mentiras: historias ciertas en medios con prestigio social

Las más prestigiosas publicaciones del mundo difunden informaciones falsas... de vez en cuando. La cantidad de veces que esto se ha producido en los últimos tiempos empieza a inquietar a la profesión y a la sociedad. El texto relata casos relevantes en los que medios de comunicación o publicaciones científicas han publicado informaciones que, posteriormente, se demostraron falsas

Green Carbon: Making sustainable agriculture real

The concept of sustainable development has evolved from a mere movement for the protection of the environment, to other multidimensional approaches. Indeed, today it calls for a holistic approach, seeking to preserve and improve not only the environment, but also to achieve social equity and economic sustainability. In Europe, society demands quality and safe products, not only in the industrial sector but also in agriculture. According to FAO, sustainable agriculture development is a key element of the new global challenges to meet human food security needs at 2050. Unsustainable practices based on intensive soil tillage and agro-chemical applications have increased agri-environmental risks. Whereas world’s food needs are expected to increase by 70% by 2050, agricultural land in Europe will also have to face environmental, economic and social challenges related to sustainable agriculture. As a result, in the EU 2020 Strategy, it is expressed that the new Common Agricultural Policy (CAP) is required to contribute to smart, sustainable and inclusive growth, enhancing social well-being, providing ecosystem services, managing resources sustainably while avoiding environmental degradation. There is broad consensus within the scientific sector that human actions generate a large portion of the greenhouse gas (GHG) emissions, causing global warming. Certainly, Kyoto Protocol states it. According to the European Environmental Agency (EEA), there has been a decrease of 17% in GHG emissions between 1990 and 2009. However, EEA also stressed the importance of the agricultural contribution to total emissions (10.3%). The fossil fuel used in agricultural field operations, along with increasing CO2 emissions from soil through tillage, are considered to be one of the main direct sources of GHG emissions from agriculture sector. Increased inputs required to sustain conventional agriculture also adds significantly to total GHG emissions. Therefore, intensification of production through tillage, agro-chemicals and heavy machinery, which characterizes conventional agriculture in Europe, strongly contributes to increased net GHG emissions instead of mitigating global warming. Sustainable agricultural soil management is crucial for mitigating climate change, especially for the restoration of lost soil organic carbon. In fact, "Agricultural soils management" is recognized as one of the 15 most promising technology options for reducing GHG emissions in the COM (2005) 35 final "Winning the battle against global climate change." The Green Carbon Conference aims to show sustainable management of agricultural soils can help to agriculture mitigate and adapt to climate change, being compatible with the objectives of environmental protection, enhancing biodiversity and supporting farmers’ welfare along with many other environmental, economic and social benefits. Over the last decade, Conservation Agriculture has become known as a set of interlinked agricultural practices, of no or minimum mechanical soil disturbance, maintenance of soil mulch cover, and diversified cropping system, capable of: (a) overcoming several of the severe sustainability limitations of conventional agriculture; and (b) raising productivity, enhancing resilience, reducing degradation and increasing the flow of ecosystem services. The discussion around both the Soil Thematic Strategy initiated in 2002, and the JRC SoCo (Soil Conservation) project clearly recognized the potential of Conservation Agriculture in mitigating and even reversing the problems of soil erosion, soil organic matter decline, soil compaction, loss of biodiversity, climate change vulnerability, among others. Whereas Conservation Agriculture is now practiced successfully on more than 125 million hectares worldwide, Europe has shown to be reluctant with regard to its adoption, despite many promising results confirming its suitability in Europe. Therefore, this European Conference on Green Carbon provides an opportunity to take a leap forward in terms of sharing farmers experiences on Conservation Agriculture across Europe, reviewing the recent progress made in knowledge generation regarding Conservation Agriculture, and to disseminate the outcomes of the currently running LIFE+ Agricarbon (LIFE08 ENV/E/000129). The slogan of ‘Green Carbon’ chosen for this Conference attempts to clarify and highlight the indivisible yet vital link between soil organic carbon and the role that soil health plays in the sustainability of agricultural production and in the flow of ecosystem services. Nevertheless, the topics addressed by the Green Carbon Conference are not only related to the importance of soil organic carbon for the overall soil quality and health, but also include other sustainability issues intimately related to the role of soil carbon such as landscape scale ecosystem functions and services, climate change mitigation and carbon offset, and economic aspects. This Conference also seeks to alert and inform EU policy stakeholders and technical officers of the urgent need to adopt sustainable soil and production practices of Conservation Agriculture to contribute to the objectives of Europe 2020, the EU's growth strategy for the coming decades

Casimir effect in the nonequilibrium steady-state of a quantum spin chain

We present a fully microscopics-based calculation of the Casimir effect in a nonequilibrium system, namely an energy flux driven quantum XX chain. The force between the walls (transverse-field impurities) is calculated in a nonequilibrium steady state which is prepared by letting the system evolve from an initial state with the two halves of the chain prepared at equilibrium at different temperatures. The steady state emerging in the large-time limit is homogeneous but carries an energy flux. The Casimir force in this nonequilibrium state is calculated analytically in the limit when the transverse fields are small. We find that the the Casimir force range is reduced compared to the equilibrium case, and suggest that the reason for this is the reduction of fluctuations in the flux carrying steady state.Comment: 11 page

Formability of the 5754-aluminum alloy deformed by a modified repetitive corrugation and straightening process

Sheets of 5754-aluminum alloy processed by a modified repetitive corrugation and straightening (RCS) process were tested in order to measure their formability. For this purpose, forming limit curves were derived. They showed that the material forming capacity decreased after being processed by RCS. However, they kept good formability in the initial stages of the RCS process. The formability study was complemented with microstructural analysis (derivation of texture) and mechanical tests to obtain the strain-rate sensitivity. The texture analysis was done by employing X-ray diffraction, obtaining pole figures, and the orientation distribution function. It was noticed that the initial texture was conserved after successive RCS passes, but the intensity dropped. RCS process did not induce ß-fiber, contrary to common deformation process. The strain-rate sensitivity coefficient was measured through tensile tests at different temperatures and strain rates; the coefficient of the samples processed after one and two passes were still relatively high, indicating the capacity to delay necking, in agreement with the good formability observed in the initial passes of the RCS processPeer ReviewedPostprint (published version

High-fidelity, broadband stimulated-Brillouin-scattering-based slow light using fast noise modulation

We demonstrate a 5-GHz-broadband tunable slow-light device based on stimulated Brillouin scattering in a standard highly-nonlinear optical fiber pumped by a noise-current-modulated laser beam. The noise modulation waveform uses an optimized pseudo-random distribution of the laser drive voltage to obtain an optimal flat-topped gain profile, which minimizes the pulse distortion and maximizes pulse delay for a given pump power. Eye-diagram and signal-to-noise ratio (SNR) analysis show that this new broadband slow-light technique significantly increases the fidelity of a delayed data sequence, while maintaining the delay performance. A fractional delay of 0.81 with a SNR of 5.2 is achieved at the pump power of 350 mW using a 2-km-long highly nonlinear fiber with the fast noise-modulation method, demonstrating a 50% increase in eye-opening and a 36% increase in SNR compared to a previous slow-modulation method

Influence of the molecular interaction in the value of molecular volume for the isotropicnematic transition of p-azoxianisol using th emodel HERSW in conjuntion with IPCM model

In this work, we analyzed the experimental pressure-temperature behavior in the Isotropic-Nematic phase transitionfor the liquid crystal p-azoxianisol at 1 atm using a development for the HERSW Conveg Peg model. Additionally, we obtained the values of the molecular volumes for the hard and attractive cores from theoretical quantum calculations at PM3, PM6 and B3LYP/6-311++G levels considering the molecular interaction among the liquidcrystals (PAA)5. We found that the best prediction for experimental data appears when the effect of the molecular interaction is considered in the volume calculation. Specifically for a/b=3.7, V0=70.86 A3 and a/bl=1.95 the best prediction was obtained