Visualization of database structures for information retrieval

This paper describes the Book House system, which is designed to support children's information retrieval in libraries as part of their education. It is a shareware program available on CD‐ROM or floppy disks, and comprises functionality for database searching as well as for classifying and storing book information in the database. The system concept is based on an understanding of children's domain structures and their capabilities for categorization of information needs in connection with their activities in schools, in school libraries or in public libraries. These structures are visualized in the interface by using metaphors and multimedia technology. Through the use of text, images and animation, the Book House encourages children ‐ even at a very early age ‐ to learn by doing in an enjoyable way, which plays on their previous experiences with computer games. Both words and pictures can be used for searching; this makes the system suitable for all age groups. Even children who have not yet learned to read properly can, by selecting pictures, search for and find those books they would like to have read aloud. Thus, at the very beginning of their school life, they can learn to search for books on their own. For the library community, such a system will provide an extended service which will increase the number of children's own searches and also improve the relevance, quality and utilization of the book collections in the libraries. A market research report on the need for an annual indexing service for books in the Book House format is in preparation by the Danish Library Centre A/S

Weed management in grain legumes using an intercropping approach

Grain legumes benefit the farming system via symbiotic N2 fixation and subsequent residue incorporation contributing to soil fertility together with their effect as break-crop in cereal rich rotations. However, grain legumes are weak competitors towards weeds and consequently weeds constitute a major problem. Since the European policies for reducing the negative effects of agricultural plant production on the environment point to reductions in pesticide use (Mortensen et al., 2000), there is a requirement to further develop strategies to reduce weeds. Intercropping involves the simultaneous growing of several plant species in the same field and the cropping strategy is known to involve interspecific interferences increasing the use of plant growth resources in space and time (Ofori and Stern, 1987) improving crop competitive ability towards weeds (Hauggaard-Nielsen et al., 2001). The main objectives of the present study was to determine the effects of grainlegume-cereal intercropping on the weed biomass production as compared to the respective sole crops using successive harvests in a three-year field study

Stabilization and plant uptake of N from 15N-labelled pea residue 16.5 years after incorporation in soil

The decline of N from 15N-labelled mature pea residues was followed in unplanted soil over 16.5 yr. Eight years after residue incorporation, 24% of the residue 15N input was still present in the soil and, after 16.5 yr, 16% of the residue 15N input remained. A double exponential model successfully described the decay of N from 15N-labelled pea residues. The total residual 15N declined with average decay constants of 1.45 yr−1 for the 30 d to 1 yr period and of 0.07 yr−1 for the 1–16 yr period. Sixteen years following incorporation of the residues, indicator plants growing in residues-amended soils were obtaining 1.7% of their N from residue N. This is, to our knowledge, the longest study on decay of N in soils from 15N-labelled crop residues. The current study thus provides a unique data set for our empirical understanding of N-dynamics in agricultural systems, which is a prerequisite to parameterize and validate N-simulation models

Competitive ability of grain legume-barley intercrops towards volunteer crops and weeds

Field pea (Pisum sativum L.) and blue lupin (Lupinus angustifolius L.) were either sole cropped or inter-cropped with barley (Hordeum vulgare L.) at two levels of nitrogen application to determine the effects of interspecific interaction in an intercrop and nitro-gen fertility on competitive ability towards volunteer crops - exemplified by red clover (Trifolium pratense). The dynamically change of competitive ability by intercropped species over time was shown to be im-portant in order to reduce opportunities for growth of volunteer crops and weed

Why diversify annual biomass production for energy – exemplified by green house gas emissions from the Danish IBUS bioethanol production concept

There is a need for integrating the biomass starting point into the energy manufacturing steps. It will secure that bioenergy is produced with limited use of non-renewable fossil fuel to secure that in the application of biomass a net emission reduction of green house gasses take place along the whole chain. Intercropping, defined as the cultivation of two or more species simultaneously on the same area of land, is an traditional practice still widespread in the tropics and common in developed countries before the ‘fossilization’ of agriculture. This cropping strategy is based on the manipulation of plant interactions in time and space to optimize resource use and productivity. It is regarded as the practical application of basic ecological principles such as diversity, competition and facilitation (Hauggaard-Nielsen et al., 2007). Cereal-legume annual intercropping show the possibility to increase input of leguminous symbiotic nitrogen (N) fixation into cropping systems reducing the need for fertilizer N applications (Jensen, 1996). Moreover, less need for pesticides are obtained due to improved competition towards weeds (Hauggaard-Nielsen et al., 2001) and less general damages on intercropped species by pest and disease organisms (Hauggaard-Nielsen et al., 2007). Intercropping is a more adaptive management practice as compared to the present arable crop rotations consisting mainly of sole crops. Perennials like clover-grass intercrops or mixtures are obviously more diversified than traditional annual crops. Clover-grass leys are important in many agroecosystems today due to quality as feed for livestock, a high dry matter production (10 t ha-1 yr-1 unfertilized, where 95% of the N accumulation is N2 fixed by clover (Jørgensen et al., 1999) providing a nitrogen-rich residue, which may significantly reduce fertilizer requirements for the succeeding crop when mineralized (Hauggaard-Nielsen et al., 1998). Furthermore, clover-grass lays can be harvested several times a year and processed to ethanol throughout the year. It is very much questioned whether bioethanol is a sustainable energy resource that can offer environmental and long-term economic advantages over fossil fuels, like gasoline or diesel. The aim of the present presentation is to debate the substitution of fossil fuels by crop biomass requiring the right selection of plant species according not only to chemical quality for efficient conversion but also to secure the development of ecologically benign farming system including biomass for energy

The effects of different seeding rates on nitrogen acquisition in pea-wheat intercropping

Intercropping may improve the use of environmental resources in low-input agricultural systems compared to sole crops and it is possible that risk may be reduced in intercropping, leading to more stable yields and weed control. The aim of the present study was to determine the effect of seeding rate of a normal leafed cultivar and a semileafless pea cultivar (Pisum sativum L.) grown as sole crops, cultivar mixture, and in double and triple intercrops with spring wheat (Triticum aestivum L.) on competitive dynamics, yield and use of nitrogen sources from soil, and symbiotic N2 fixation. A randomized complete blocks experiment design was used. The differences between the treatments were not significant for total grain yield. Land equivalent ratios for grain yield varied between 1.04 (80P/20W) and 1.40 (80D/20W), which showed that plant growth factors are used more efficiently by the intercrops than by the sole crops for grain production. Nitrogen accumulation was higher in pea sole crops compared to pea component crops in the intercrops, due to the decreased pea density and decreased pea growth caused by interspecific competition from wheat. The amount of N2 fixed in pea in the intercrops at the flowering harvest was less than the i n the pea sole crop also due to competition from wheat for other growth factors than nitrogen, probably by shading. It was concluded that pea-wheat intercropping can use N resources more efficiently compared to sole crops in sustainable cropping system

Modelling Population Exposure to Traffic Air Pollution Using GIS

The paper outlines the background, methodology and perspectives for an ongoing Danish PhD project concerning exposure of the Danish population to traffic air pollution. The objective of the research project is to develop a model for population exposure to traffic induced air pollution in Denmark in order to improve assessment of the health impacts of traffic air pollution and the impact of various urban and traffic control strategies to reduce the population's exposure to traffic air pollution. Part of the project is to establish a population exposure model for an urban environment as a case study. The model will combine modelled air pollution data and population data using a Geographic Information System (ArcView). The air pollution will be modelled using the Danish Operational Street Pollution Model (OSPM). A simple population dynamics model will be established to model the number of people which simultaneously are present at a given area during a given time period. The project is a part of a PhD study funded by the Danish Transport Council and the Danish Research Academy. The study is appointed 2.5 years and terminates June 1997

Quantification of root fungi using signature fatty acids

Both deleterious (pathogenic) and beneficial (mycorrhizal) fungi inhabit plant roots with strong impact on plant growth and health. Various methods have been used to quantify these fungi, such as indirect measurements of plant parameters, disease index, staining techniques and serological/genetic/biochemical markers. The objective of this work is to evaluate the possibility of using signature fatty acids to quantify root-inhabiting fungi in planta and in soil. Different fatty acid-based methods can be used to quantify fungi. Phospholid fatty acids (PLFA) can be used for biomass estimation and neutral lipid fatty acids (NLFA) for estimation of fungal energy reserves and the NLFA/PLFA ratio can give information on the physiological status of the fungus. It is quite laborious to make PLFA and NLFA analyses; so whole cell fatty acid (WCFA) analyses, which are much faster, can be used as a faster alternative to give information of root infection intensity. Signature fatty acids have been used to quantify arbuscular mycorrhizal fungi (16:1ω5) and the pea root pathogen Aphanomyces euteiches (14:1ω9). Recently, we have further used arachadonic acid (20:4) to estimate root infection intensity of the plasmodiophorids Plasmodiophora brassica, causing club root in cabbage and Spongospora subterranea, the vector of mop top potato virus. Specificity of the various signature fatty acids of root-inhabiting fungi are discussed in relation to quantifying these fungi in both controlled greenhouse pot experiments and in the field. Furthermore, the possibility of using signature fatty acids to estimate soil inoculum potential of root-inhabiting fungi are discussed

Multi-Agent Programming Contest 2010 - The Jason-DTU Team

We provide a brief description of the Jason-DTU system, including the methodology, the tools and the team strategy that we plan to use in the agent contest.Comment: 4 page