Darkness visible: reflections on underground ecology

1 Soil science and ecology have developed independently, making it difficult for ecologists to contribute to urgent current debates on the destruction of the global soil resource and its key role in the global carbon cycle. Soils are believed to be exceptionally biodiverse parts of ecosystems, a view confirmed by recent data from the UK Soil Biodiversity Programme at Sourhope, Scotland, where high diversity was a characteristic of small organisms, but not of larger ones. Explaining this difference requires knowledge that we currently lack about the basic biology and biogeography of micro-organisms. 2 It seems inherently plausible that the high levels of biological diversity in soil play some part in determining the ability of soils to undertake ecosystem-level processes, such as carbon and mineral cycling. However, we lack conceptual models to address this issue, and debate about the role of biodiversity in ecosystem processes has centred around the concept of functional redundancy, and has consequently been largely semantic. More precise construction of our experimental questions is needed to advance understanding. 3 These issues are well illustrated by the fungi that form arbuscular mycorrhizas, the Glomeromycota. This ancient symbiosis of plants and fungi is responsible for phosphate uptake in most land plants, and the phylum is generally held to be species-poor and non-specific, with most members readily colonizing any plant species. Molecular techniques have shown both those assumptions to be unsafe, raising questions about what factors have promoted diversification in these fungi. One source of this genetic diversity may be functional diversity. 4 Specificity of the mycorrhizal interaction between plants and fungi would have important ecosystem consequences. One example would be in the control of invasiveness in introduced plant species: surprisingly, naturalized plant species in Britain are disproportionately from mycorrhizal families, suggesting that these fungi may play a role in assisting invasion. 5 What emerges from an attempt to relate biodiversity and ecosystem processes in soil is our extraordinary ignorance about the organisms involved. There are fundamental questions that are now answerable with new techniques and sufficient will, such as how biodiverse are natural soils? Do microbes have biogeography? Are there rare or even endangered microbes

Collaborative Learning of Term-Based Concepts for Automatic Query Expansion

Information Retrieval Systems have been studied in Computer Sci- ence for decades. The traditional ad-hoc task is to find all documents relevant for an ad-hoc given query but the accuracy of ad-hoc document retrieval systems has plateaued in recent years. At DFKI, we are working on so-called collaborative information retrieval (C1R) systems which unintrusively learn from their users search processes

Comparative efficiency of domestic hot water systems

2. ed.; Reports supersede nos 57800/1 and 57800/2, pub. Aug 1989; Work carried out for Waterheater Manufacturers AssociationSIGLEAvailable from British Library Document Supply Centre- DSC:7389.20(BSRIA--57800/1-2) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Comparative efficiency of domestic hot water systems

2. ed.; Reports supersede nos 57800/1 and 57800/2, pub. Aug 1989; Work carried out for Waterheater Manufacturers AssociationSIGLEAvailable from British Library Document Supply Centre- DSC:7389.20(BSRIA--57800/1-2) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Improving document retrieval by automatic query expansion using collaborative learning of term-based concepts

Abstract. Query expansion methods have been studied for a long time – with debatable success in many instances. In this paper, a new approach is presented based on using term concepts learned by other queries. Two important issues with query expansion are addressed: the selection and the weighing of additional search terms. In contrast to other methods, the regarded query is expanded by adding those terms which are most similar to the concept of individual query terms, rather than selecting terms that are similar to the complete query or that are directly similar to the query terms. Experiments have shown that this kind of query expansion results in notable improvements of the retrieval effectiveness if measured the recall/precision in comparison to the standard vector space model and to the pseudo relevance feedback. This approach can be used to improve the retrieval of documents in Digital Libraries, in Document Management Systems, in the WWW etc.

Improving Document Transformation Techniques with Collaborative Learned Term-based Concepts. In

Abstract. Document Transformation techniques have been studied for decades. In this paper, a new approach for a significant improvement is presented based on using a new query expansion method. In contrast to other methods, the regarded query is expanded by adding those terms that are most similar to the concept of individual query terms, rather than selecting terms that are similar to the complete query or that are directly similar to the query terms. Experiments have shown that Document Transformation techniques are significantly improved in the retrieval effectiveness when measuring the recall-precision.