982 research outputs found

    Planteproduktion og fødevalg

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    Den overordnede baggrund for projektet var at få nogle kvantitative beskrivelser af, hvorledes man med forskellige former for ekstensiv græsmarksdrift kunne besvare eller øge artsdiversiteten på ferske enge. Samtidig ønskedes at kvantificere konsekvenserne for den landbrugsmæssige produktion på arealerne. Ferske enge varierer meget med hensyn til plantebestand, jordbundsforhold og fugtighed, og det er derfor væsentligt at kende disse faktorer, når man skal vurdere, hvilken produktion, der kan forventes på et givet engareal. Når stude og får afgræsser på halvkulturarealer er der et større udvalg af arter end der er på intensive græsmarker. Desuden er der som regel en lavere belægning, hvilket betyder at dyrene har gode muligheder for at selektere i det planteudbud, der er til rådighed. Målet med denne del af undersøgelsen var at få en beskrivelse af produktionens størrelse, foderkvalitet, artssammensætning, benyttelsens indvirkning på arterne, foderkvaliteten af enkeltarter og studenes fødevalg

    An extendable modular endoprosthetic system for bone tumour management in the leg

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    A modular endoprosthetic system has been developed at the Groningen University Hospital and the University of Twente. The system can bridge a defect resulting from the resection of a malignant bone tumour which has developed around the knee joint of a child. Since the other healthy leg continues to grow, the system includes an element whose length can be adjusted non-invasively by using an external magnetic field. In addition to this lengthening element, there are one hip and two knee components, connectors of various lengths, and fixation elements. The paper describes the elements of the modular endoprosthetic system. Tables are created by means of which the elemental composition of such an endoprosthesis can be determined for each individual patient

    Accelerating cycle expansions by dynamical conjugacy

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    Periodic orbit theory provides two important functions---the dynamical zeta function and the spectral determinant for the calculation of dynamical averages in a nonlinear system. Their cycle expansions converge rapidly when the system is uniformly hyperbolic but greatly slowed down in the presence of non-hyperbolicity. We find that the slow convergence can be associated with singularities in the natural measure. A properly designed coordinate transformation may remove these singularities and results in a dynamically conjugate system where fast convergence is restored. The technique is successfully demonstrated on several examples of one-dimensional maps and some remaining challenges are discussed

    Expedition 306 summary

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    The overall aim of the North Atlantic paleoceanography study of Integrated Ocean Drilling Program Expedition 306 is to place late Neogene–Quaternary climate proxies in the North Atlantic into a chronology based on a combination of geomagnetic paleointensity, stable isotope, and detrital layer stratigraphies, and in so doing generate integrated North Atlantic millennial-scale stratigraphies for the last few million years. To reach this aim, complete sedimentary sections were drilled by multiple advanced piston coring directly south of the central Atlantic “ice-rafted debris belt” and on the southern Gardar Drift. In addition to the North Atlantic paleoceanography study, a borehole observatory was successfully installed in a new ~180 m deep hole close to Ocean Drilling Program Site 642, consisting of a circulation obviation retrofit kit to seal the borehole from the overlying ocean, a thermistor string, and a data logger to document and monitor bottom water temperature variations through time

    Assessment of the Socio-Economic Impact of Late Blight and State of the Art of Management in European Organic Potato Production Systems

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    In Europe, late blight, caused by Phytophthora infestans, is the most devastating disease affecting organic (and conventional) potato production. Under suitable environmental conditions the disease can spread rapidly and it can cause complete crop loss. The extent of damage due to late blight depends on several factors: in organic production systems these factors include climate, choice of variety, soil management and use of crop protection agents such as copper. Therefore, the extent of economic damage varies between European regions. Council Regulation (EEC) No 2092/91, amended by Commission Regulation (EC) No 473/2002 of 15 March 2002 regulates the use of copper in organic agriculture. Copper has been the single most important control agent in organic late blight control. Therefore, the reduction or an eventual phasing out of copper use will have varying impacts in different regions. This report presents the results of a detailed survey that has been conducted in 7 European countries in the year 2001. It is a subproject of the EU-funded project Blight-MOP (QLRT 31065). The survey investigates legislative, socio-economic and production parameters. The aim of this study was: (i) to obtain an inventory of the current organic potato production techniques, (ii) to assess the impact of a potential ban of copper on yields and viability of organic potato production and (iii) to identify alternative plant protection strategies that are used by organic farmers. This report includes: (i) statistics on yields, farm gate prices, and production techniques, (ii) an analysis offarmer observations and experiences on the extent and impact of late blight epidemics, (iii) an analysis of the farmer’s motivations, expectations and their assessment of the potential impact of a copper ban. Using multiple linear regression we identified production factors which appear to consistently contribute to production success

    Shrinking a large dataset to identify variables associated with increased risk of Plasmodium falciparum infection in Western Kenya

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    Large datasets are often not amenable to analysis using traditional single-step approaches. Here, our general objective was to apply imputation techniques, principal component analysis (PCA), elastic net and generalized linear models to a large dataset in a systematic approach to extract the most meaningful predictors for a health outcome. We extracted predictors for Plasmodium falciparum infection, from a large covariate dataset while facing limited numbers of observations, using data from the People, Animals, and their Zoonoses (PAZ) project to demonstrate these techniques: data collected from 415 homesteads in western Kenya, contained over 1500 variables that describe the health, environment, and social factors of the humans, livestock, and the homesteads in which they reside. The wide, sparse dataset was simplified to 42 predictors of P. falciparum malaria infection and wealth rankings were produced for all homesteads. The 42 predictors make biological sense and are supported by previous studies. This systematic data-mining approach we used would make many large datasets more manageable and informative for decision-making processes and health policy prioritization
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