9 research outputs found
Shear viscosity of a crosslinked polymer melt
We investigate the static shear viscosity on the sol side of the
vulcanization transition within a minimal mesoscopic model for the
Rouse-dynamics of a randomly crosslinked melt of phantom polymers. We derive an
exact relation between the viscosity and the resistances measured in a
corresponding random resistor network. This enables us to calculate the
viscosity exactly for an ensemble of crosslinks without correlations. The
viscosity diverges logarithmically as the critical point is approached. For a
more realistic ensemble of crosslinks amenable to the scaling description of
percolation, we prove the scaling relation between the critical
exponent of the viscosity, the thermal exponent associated with the
gel fraction and the crossover exponent of a random resistor network.Comment: 8 pages, uses Europhysics Letters style; Revisions: results extende
The contribution of the European Society for Soil Conservation (ESSC) to scientific knowledge, education and sustainability
Soil is an integral component of the global environmental system which supports the quality and diversity of terrestrial life on Earth. Therefore, it is vital to consider the processes and impacts of soil degradation on society, especially on the provision of environmental goods and services, including food security and climate change mitigation and adaptation. Scientific societies devoted to soil science play significant roles in reducing soil degradation and promoting soil conservation by advancing scientific knowledge, education and environmental sustainability.
The ESSC was founded on 4 November 1988, with the aims to:
1.
Support research on soil degradation, soil protection and soil and water conservation.
2.
Provide a network for the exchange of knowledge about soil degradation processes and soil conservation research and practises.
3.
Produce publications on major issues relating to soil degradation and soil and water conservation.
4.
Advise regulators and policy-makers on soil issues, especially soil degradation, protection and conservation.
The societal challenges that can be addressed through better soil protection, advancing knowledge and scientific approaches to soil protection and sustainable management, mean the ESSC embraces the on-going development, application, review and constructive criticism of highly innovative scientific soil conservation methods. In this context, the ESSC analyses and publicizes the roles and functions of soil in natural and human-modified systems and the functional optimization of soils to ensure sustainable environmental protection.
âThe thin layer of soil that forms a patchy covering over the continents controls our own existence and that of every other animal of the landâ (Rachel Carson (1962) in âSilent Springâ).European Society for Soil Conservatio
Measuring, modelling and managing gully erosion at large scales: A state of the art
Soil erosion is generally recognized as the dominant process of land degradation. The formation and expansion of gullies is often a highly significant process of soil erosion. However, our ability to assess and simulate gully erosion and its impacts remains very limited. This is especially so at regional to continental scales. As a result, gullying is often overlooked in policies and land and catchment management strategies. Nevertheless, significant progress has been made over the past decades. Based on a review of >590 scientific articles and policy documents, we provide a state-of-the-art on our ability to monitor, model and manage gully erosion at regional to continental scales. In this review we discuss the relevance and need of assessing gully erosion at regional to continental scales (Section 1); current methods to monitor gully erosion as well as pitfalls and opportunities to apply them at larger scales (section 2); field-based gully erosion research conducted in Europe and European Russia (section 3); model approaches to simulate gully erosion and its contribution to catchment sediment yields at large scales (section 4); data products that can be used for such simulations (section 5); and currently existing policy tools and needs to address the problem of gully erosion (section 6). Section 7 formulates a series of recommendations for further research and policy development, based on this review. While several of these sections have a strong focus on Europe, most of our findings and recommendations are of global significance.info:eu-repo/semantics/publishedVersio