Rheology of Weakly Vibrated Granular Media

We probe the rheology of weakly vibrated granular flows as function of flow rate, vibration strength and pressure by performing experiments in a vertically vibrated split-bottom shear cell. For slow flows, we establish the existence of a novel vibration dominated granular flow regime, where the driving stresses smoothly vanish as the driving rate is diminished. We distinguish three qualitatively different vibration dominated rheologies, most strikingly a regime where the shear stresses no longer are proportional to the pressure.Comment: 14 pages, 19 figures, submitted to PR

First-principles calculations of the crystal structure, electronic structure, and thermodynamic stability of Be(BH4)2

Alanates and boranates are intensively studied because of their potential use as hydrogen storage materials. In this paper, we present a first-principles study of the electronic structure and the energetics of beryllium boranate BeBH42. From total energy calculations, we show that—in contrast to the other boranates and alanates—hydrogen desorption directly to the elements is likely and is at least competitive with desorption to the elemental hydride BeH2. The formation enthalpy of BeBH42 is only −0.14 eV/H2 at T=0 K. This low value can be rationalized by the participation of all atoms in the covalent bonding, which is in contrast to the ionic bonding observed in other boranates. From calculations of thermodynamic properties at finite temperature, we estimate a decomposition temperature of 162 K at a pressure of 1 bar

Individual strategies of aggressive and non-aggressive male mice in encounters with trained aggressive residents

To determine whether individual differences in offensive behaviour are related to differences in defensive behaviour, the responses of male wild house mice, Mus domesticus, of an aggressive and a non-aggressive line to defeat by physically stronger residents were analysed. Individuals of the aggressive line engaged in more flight behaviour, whereas the males of the non-aggressive line predominantly showed immobility. The higher flight tendency of the aggressive intruders provoked more attacks by the resident, resulting in more fighting between the resident and an aggressive male than between the resident and a non-aggressive intruder. However, if offered an opportunity to escape from the home-cage of the resident, aggressive males more readily made use of it than non-aggressive intruders. Differences between aggressive and non-aggressive male mice are interpreted in terms of fundamentally different behavioural strategies adopted in response to social interaction. The response of aggressive males can be characterized as an active behavioural strategy by which they tend to determine actively their social situation. In contrast, the prevailing lack of overt attempts to manipulate the situation by the non-aggressive mice points to passive confrontation, in an offensive as well as in a defensive context.

Impact of EU Biofuel Policies on World Agricultural and Food Markets

This paper assesses the global and sectoral implications of the EU biofuels directive in a multi-region computable general equilibrium framework. Our results show that without mandatory blending or subsidies to stimulate the use of biofuel crops in the petroleum sector the targets of the EU Biofuel directive will not the reached in 2010. With mandatory blending the enhanced demand for biofuel crops has a strong impact on agriculture at the global and European level. The additional demand from the energy sector might slow down or reverse the long term process of declining agricultural prices.Biofuels, EU biofuel directive, agricultural markets, Computable General Equilibrium modeling, Agribusiness, International Relations/Trade, Research and Development/Tech Change/Emerging Technologies, Resource /Energy Economics and Policy,

Modelling the Consequences of Increasing Bioenergy Demand on Land and Feed Use

Bioenergy Production, CGE modeling, Land Demand, Feed Demand, Agricultural and Food Policy, Farm Management, Land Economics/Use,

Agricultural Incomes Development in EU till 2030: Scenario Analysis of Main Driving Factors

Europe’s rural areas are expected to witness rapid changes due to developments in demography, (agricultural) policies, global trade, climate change, technology and enlargement of the European Union. These changes will affect farmers’ production and income level and make the final outcome of this process uncertain. This paper tries to assess this uncertainty by analyzing the results of 34 scenarios of the EURURALIS project. The scenario outcomes were used to investigate agricultural income development and to analyze the impact of different combinations of macroeconomic and policy factors on agricultural income. The results of these scenarios were achieved in a modeling framework consisting of a modified version of the Global Trade Analysis Project model (GTAP) and the more ecological-environmental oriented Integrated Model to Assess the Global Environment (IMAGE).Agricultural incomes and production, agricultural policy, long-term scenarios,

Impact of the EU Biofuels Directive on the EU food supply chain

The paper investigates the impact of the EU Biofuels Directive (BFD) on the EU agri-food supply chain using the computable general equilibrium model of the world economy named LEITAP. LEITAP is an extended version of the Global Trade Analysis Project (GTAP) model including an improved land market modeling, substitution possibilities between capital and energy as well as between different energy sources including biofuels, feed byproducts of the biofuel production process and substitution between different feed components and feed byproducts. The simulation results shows that the implementation of the EU BFD has a pronounced impact on the markets of cereals, oilseeds and sugar and shows only a limited impact on production and consumption of other agrifood commodities which are not directly affected by biofuel production. The harvested area and production of biofuel crops (grains, oilseeds) is expected to increase by 17% and 25% respectively and sugar production by 12% as a direct result the BFD. The EU-imports of these commodities are expected to rise more than twice. The increasing demand for biofuel crops and sugar will lift domestic prices of these commodities by 25% and 19% respectively but overall agri-food price inflation will be limited to 3% in the EU and to less than 1% at world market level.EU Biofuels Directive, food supply chain, indirect land use changes, computable general equilibrium model., Agricultural and Food Policy,