132,121 research outputs found
Promoting wild bees in European agricultural landscapes. The role of floral resources in driving and mitigating wild bee decline
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143958.pdf (Publisher’s version ) (Open Access)Radboud Universiteit Nijmegen, 18 september 2015Promotores : Siepel, H., Schaminee, J.H.J. Co-promotor : Kleijn, D.176 p
Species richness and weed abundance in the vegetation of arable field boundaries
No full textIn the modem arable landscape, the vegetation of perennial field boundaries have important ecological functions such as providing a habitat for farmland wildlife, providing overwintering sites for predatory insects, providing movement corridors, reducing soil erosion and acting as an agrochemical buffer. In recent decades, plant diversity in these linear landscape structures has declined severely. The present study aims at identifying the most important factors that control botanical species richness in herbaceous arable field boundaries. The field boundary vegetation is usually managed by farmers who consider the boundary to be a source of weeds. Therefore, research concentrated on factors that simultaneously increase species richness and reduce weed abundance in the boundary vegetation.Species richness was primarily affected by an accumulation of nutrients in the field boundary. Nutrients may reach the boundary in two ways: (i) by misplacement of fertilizer and (ii) by capture of arable nutrient resources (through root growth into the field) by plants in field boundaries. The high nutrient levels in the boundary resulted in an increased productivity of the vegetation and a dominance of tall, competitive species. Subsequently, low statured species disappeared from the habitat and species richness declined. The most common type of boundary management practiced by farmers did not include removal of the cut material after mowing which strengthens the eutrophication of arable field boundaries. Herbicide drift had adverse effects on species richness but the effects were less severe and consistent compared to the effects of nutrients.The main factor promoting weed growth (in the study area primarily the clonal weeds Cirsium arvense and Elymus repens) was the presence of bare soil in the boundary. Bare soil may be created by cultivation activities of the farmer or by the smothering effects of cut material left lying in the boundary after mowing. Bare soil generally promotes the establishment of annual weed species. Furthermore, the perennial weed Elymus repens was found to be able to concentrate its biomass selectiveley in bare patches within the perennial vegetation. Additionally, bare soil was found to favour the establishment of tall competitive (early successional) species compared to later successional species which are indicative of more species rich plant communities.The results of this study suggest that boundaries that are not regularly disturbed and low to moderately productive combine species richness with low weed abundance. This may be achieved by a regular and consistent mowing regime of the boundary vegetation that includes removal of the cuttings. A boundary management approach is suggested which may be combined easily with other farming activities
Risk factors in women's health in different stages of life.
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127371.pdf (Publisher’s version ) (Open Access)Radboud Universiteit Nijmegen, 26 juni 2014Promotores : Lagro-Janssen, A.L.M., Schellevis, F.G. Co-promotor : Kleijn, M.J.J. d
‘Kunstbloem’ in finale Bio-Art & Design
No full textHoe ziet het landschap eruit als bijen op een kunstbloem met gekleurde pollen foerageren? Als een Van Gogh? Het idee levert onderzoeker David Kleijn een plek op in de finale van de Bio-Art & Design competitie. Synthetic Pollinizer heet het project dat Kleijn samen met de Australische kunstenaar Michael Candy uit wil voeren. En die ‘Kunstbloem’ komt er als het duo bij de eerste drie van de BAD-Award eindigt. Dan ligt er 25.000 euro te wachten om het bestuivingsproject daadwerkelijk uit te voeren
Randomness of RCTs investigating effects of vitamine D on depression
No full textFabricated data contaminates the evidence synthesised in meta-analyses. in randomized controlled trials (RCTs), between-group sampling variability in baseline variables should show predictable patterns. Assessment of the patterns of variability can be performed through Monte-Carlo simulations. When the results of these analyses show that patterns deviate from the expected, it is likely the data is not generated by the process of randomisation. Inspired by Carlisle, and based on our previous work (Langeveld et al., under review, preregistration: https://osf.io/8mtg6), we explore non-randomness in baseline variables and unusual patterns drop-out rates in RCTs investigating potential efficacy of vitamine D supplementation on depression.
Carlisle, J. B. (2012). The analysis of 168 randomised controlled trials to test data integrity. Anaesthesia, 67(5), 521-537.
Langeveld, D., Sipahioğlu, B., de Kleijn, R., and Molendijk, M.L.. Non-randomness in 224 randomized controlled treatment trials. Under review Lancet Psychiatry (29/03/2025)
Flow, heat and mass transfer through CBRN protective clothing
No full textChemical EngineeringApplied Science
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Effects of grazing and biogeographic regions on grassland biodiversity in Hungary – analysing assemblages of 1200 species
No full textAgricultural intensification is a major threat to biodiversity. Agri-environment schemes, the main tools to counteract negative impacts of agriculture on the environment, are having mixed effects on biodiversity. One reason for this may be the limited number of species (groups) covered by most studies. Here, we compared species richness and abundance of 10 different species groups on extensively (0.5 cattle/ha) and intensively (1.0–1.2 cattle/ha) grazed semi-natural pastures in 42 fields in three Hungarian regions. Plants, birds and arthropods (leafhoppers, true bugs, orthopterans, leaf-beetles, weevils, bees, carabids, spiders) were sampled. We recorded 347 plant species, 748 territories of 43 bird species, and 51,883 individuals of 808 arthropod species. Compared to West European farmlands, species richness was generally very high. Grazing intensity had minor effects on ¿ and ¿ diversity, abundance and composition of the species assemblages. Region had significant effects on species richness and abundance of four taxa, and had strong effects on ¿ diversity and species composition of all taxa. Regional differences therefore contributed significantly to the high overall biodiversity. We conclude that both grazing regimes deliver significant biodiversity benefits. Agri-environmental policy at the EU level should promote the maintenance of large scale extensive farming systems. At the national level, the effectiveness of agri-environment schemes should be improved via promoting and using research evidenc
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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