993 research outputs found

    Innovative financing mechanisms for sustainable ecosystem management

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    The increasing human influence on ecosystems and the ensuing unsustainable exploitation and degradation has led in many places to depletion and loss of function of these ecosystems. These problems cannot be solved by (innovative) financing mechanisms, as the causes do not lie in a lack of financing mechanisms. Although decifit in funding in general is an important issue - the amount of finance available for ecosystems and biodiversity falls short of the funding neede

    Development of nature-oriented dairy farm systems with an optimization model: the case of ā€˜Farming for Natureā€™ in ā€˜de Langstraatā€™, the Netherlands

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    ā€˜Farming for Natureā€™, a relatively new policy instrument being tried out in the Netherlands, is evaluated. The concept has been designed to allow dairy farmers to improve nature conservation on their farms. Under the scheme, no manure, fertilizer, or feed ā€“ concentrates or roughage - may be imported into farm systems from external sources. The feasibility of such a self-sustaining system and the conditions required for it to deliver the desired results, are explored with a farm-based linear programming model known as FIONA (Farm based Integrated Optimization Model for Nature and Agriculture). The model is explained and applied to ā€˜de Langstraatā€™, a region in southern Netherlands. The results show that levels of production under the ā€˜Farming for Natureā€™ regime are dependent upon soil fertility and the proportion of land that is suitable for growing arable crops. If all available land on a dairy farm in the scheme is arable land, then high production levels of up to 7,500 kg milk per hectare can be realized. If only 30% of the farm area is suitable for arable crops, then only lower production levels, of about 6,600 kg milk per hectare can be realized. The scheme has positive ecological effects. Both nature and cultural landscape values may benefit significantly from the concept. Improvement in ecological terms however, carries a price in terms of agricultural income. An average dairy farm adopting the concept of ā€˜Farming for Natureā€™ experiences an income loss of approximately Ć¢ā€šĀ¬ 840 per hectare in the short-run (5-10 years). More important is the observation that the scale of such farms in the short-run might be too small to earn an attractive income for its workers, even when fully compensated according to European Union regulations.nature management, dairy farming system, linear programming, farm-economics, Farm Management, Land Economics/Use,

    Making curves minimally crossing by Reidemeister moves

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    Decomposition of graphs on surfaces

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    Detection of genetically modified plant products by protein strip testing: an evaluation of real-life samples

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    The determination of the presence of genetically modified plant material by the detection of expressed genetically engineered proteins using lateral flow protein strip tests has been evaluated in different matrices. The presence of five major genetically engineered proteins (CP4-EPSPS, CryIAb, Cry9C, PAT/pat and PAT/bar protein) was detected at low levels in seeds, seed/leaf powder and leaf tissue from genetically modified soy, maize or oilseed rape. A comparison between &quot;protein strip test&quot; (PST) and &quot;polymerase chain reaction&quot; (PCR) analysis of genetically modified food/feed samples demonstrates complementarities of both techniques. -Ā® Springer-Verlag 2007</p

    Magnetohydrodynamics dynamical relaxation of coronal magnetic fields. I. Parallel untwisted magnetic fields in 2D

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    Context. For the last thirty years, most of the studies on the relaxation of stressed magnetic fields in the solar environment have onlyconsidered the Lorentz force, neglecting plasma contributions, and therefore, limiting every equilibrium to that of a force-free field. Aims. Here we begin a study of the non-resistive evolution of finite beta plasmas and their relaxation to magnetohydrostatic states, where magnetic forces are balanced by plasma-pressure gradients, by using a simple 2D scenario involving a hydromagnetic disturbance to a uniform magnetic field. The final equilibrium state is predicted as a function of the initial disturbances, with aims to demonstrate what happens to the plasma during the relaxation process and to see what effects it has on the final equilibrium state. Methods. A set of numerical experiments are run using a full MHD code, with the relaxation driven by magnetoacoustic waves damped by viscous effects. The numerical results are compared with analytical calculations made within the linear regime, in which the whole process must remain adiabatic. Particular attention is paid to the thermodynamic behaviour of the plasma during the relaxation. Results. The analytical predictions for the final non force-free equilibrium depend only on the initial perturbations and the total pressure of the system. It is found that these predictions hold surprisingly well even for amplitudes of the perturbation far outside the linear regime. Conclusions. Including the effects of a finite plasma beta in relaxation experiments leads to significant differences from the force-free case

    Directed triangles in directed graphs

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    AbstractWe show that each directed graph on n vertices, each with indegree and outdegree at least n/t, where t=5āˆ’5+1247āˆ’215=2.8670975ā‹Æ, contains a directed circuit of length at most 3
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