Staff Publications

Staff Publications

  • external user (warningwarning)
  • Log in as
  • language uk
  • About

    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

    We have a manual that explains all the features 

Records 1 - 20 / 2008

  • help
  • print

    Print search results

  • export
    A maximum of 250 titles can be exported. Please, refine your queryYou can also select and export up to 30 titles via your marked list.
  • alert
    We will mail you new results for this query: q=Leeuwen
Check title to add to marked list
Linking diagnostic features to soil microbial biomass and respiration in agricultural grassland soil : A large-scale study in Ireland
Richter, A. ; Huallacháin, D.O. ; Doyle, E. ; Clipson, N. ; Leeuwen, J.P. van; Heuvelink, G.B. ; Creamer, R.E. - \ 2018
European Journal of Soil Science 69 (2018)3. - ISSN 1351-0754 - p. 414 - 428.
The functional potential of soil ecosystems can be predicted from the activity and abundance of the microbial community in relation to key soil properties. When describing microbial community dynamics, soil physicochemical properties have traditionally been used. The extent of correlations between properties, however, differs between studies, especially across larger spatial scales. In this research we analysed soil microbial biomass and substrate-induced respiration of 156 samples from Irish grasslands. In addition to the standard physicochemical, soil type and land management variables, soil diagnostic properties were included to identify if these important soil-landscape genesis classes affected microbial biomass and respiration dynamics in Irish soil. Apart from physicochemical properties, soil drainage class was identified as having an important effect on microbial properties. In particular, biomass-specific basal (qCO2) and substrate-induced respiration (SIR:CFE) were explained best by the soil drainage. Poorly drained soil had smaller values of these respiration measures than well-drained soil. We concluded that this resulted from different groups within the microbial community that could use readily available carbon sources, which suggests a change in microbial community dynamics associated with soil texture and periods of water stress. Overall, our results indicate that soil quality assessments should include both physicochemical properties and diagnostic classes, to provide a better understanding of the behaviour of soil microbial communities. Highlights: Assessing the effect of soil diagnostic features and properties on microbial biomass and respiration A soil biological survey from 156 grassland sites in Ireland Soil drainage class has an important effect on microbial properties Soil quality assessments should include both physicochemical properties and diagnostic classes
Land in post-conflict situations : War, decentralization, land governance and state formation In Northern Uganda
Kobusingye, Doreen Nancy - \ 2018
University. Promotor(en): Han van Dijk, co-promotor(en): M. van Leeuwen. - Wageningen : Wageningen University - ISBN 9789463437721 - 142
Why do placentas evolve? Evidence for a morphological advantage during pregnancy in live-bearing fish
Fleuren, Mike ; Quicazan-Rubio, Elsa M. ; Leeuwen, Johan L. van; Pollux, Bart J.A. - \ 2018
PLoS One 13 (2018)4. - ISSN 1932-6203
A live-bearing reproductive strategy can induce large morphological changes in the mother during pregnancy. The evolution of the placenta in swimming animals involves a shift in the timing of maternal provisioning from pre-fertilization (females supply their eggs with sufficient yolk reserves prior to fertilization) to post-fertilization (females provide all nutrients via a placenta during the pregnancy). It has been hypothesised that this shift, associated with the evolution of the placenta, should confer a morphological advantage to the females leading to a more slender body shape during the early stages of pregnancy. We tested this hypothesis by quantifying three-dimensional shape and volume changes during pregnancy and in full-grown virgin controls of two species within the live-bearing fish family Poeciliidae: Poeciliopsis gracilis (non-placental) and Poeciliopsis turneri (placental). We show that P. turneri is more slender than P. gracilis at the beginning of the interbrood interval and in virgins, and that these differences diminish towards the end of pregnancy. This study provides the first evidence for an adaptive morphological advantage of the placenta in live-bearing fish. A similar morphological benefit could drive the evolution of placentas in other live-bearing (swimming) animal lineages.
Pathogenicity of Diaporthe spp. on two blueberry cultivars (Vaccinium corymbosum)
Cardinaals, J. ; Wenneker, M. ; Voogd, J.G.B. ; Leeuwen, G.C.M. van - \ 2018
EPPO Bulletin 48 (2018)1. - ISSN 0250-8052 - p. 128 - 134.
Diaporthe vaccinii causes twig blight and fruit rot and is currently listed as a quarantine organism for the European Union. In the Netherlands, two species from the same genus, Diaporthe eres and Diaporthe rudis, are regularly isolated from blighted twigs of Vaccinium corymbosum. This study compared the pathogenicity of these two species to D. vaccinii. To develop a pathogenicity test a field experiment was performed at an experimental station, testing isolates of D. rudis and D. eres. Most of the isolates tested did not cause statistically significantly larger lesions compared to the control treatment (P > 0.05). In a greenhouse experiment a similar test was conducted, comparing D. vaccinii with the closely related species D. eres. Two cultivars of blueberry, Duke and Liberty, were inoculated using two D. vaccinii and two D. eres isolates. Stem canker lesions caused by D. vaccinii were larger than these caused by D. eres isolates. The majority of the lesions caused by D. vaccinii did not pass the first node of the inoculated shoot, which might be an explanation for the ‘mild’ symptoms of D. vaccinii in V. corymbosum, which appear not to cause crop losses. The results of this study suggest that D. vaccinii may not be a major threat to blueberry production in Europe. Further data is required to be able to conclude whether the quarantine status of D. vaccinii is still appropriate.
Three-dimensional analysis of the fast-start escape response of the least killifish, Heterandria formosa
Fleuren, Mike ; Leeuwen, Johan L. Van; Quicazan-Rubio, Elsa M. ; Pieters, Remco P.M. ; Pollux, Bart J.A. ; Voesenek, Cees J. - \ 2018
Journal of Experimental Biology 221 (2018)7. - ISSN 0022-0949
3D tracking - Biomechanics - C-start - Fish behaviour - Poeciliidae - Swimming
Fish make C-starts to evade predator strikes. Double-bend (DB) C-starts consist of three stages: Stage 1, in which the fish rapidly bends into a C-shape; Stage 2, in which the fish bends in the opposite direction; and a variable Stage 3. In single-bend (SB) C-starts, the fish immediately straightens after Stage 1. Despite fish moving in threedimensional (3D) space, fast-start responses of adult fish have mainly been studied in a horizontal plane. Using automated 3D tracking of multi-camera high-speed video sequences, we show that both SB and DB fast-starts by adult female least killifish (Heterandria formosa) often contain a significant vertical velocity component, and large changes in pitch (DB up to 43 deg) and roll (DB up to 77 deg) angles. Upwards and downwards elevation changes are correlated with changes in pitch angle of the head; movement in the horizontal plane is correlated with changes in yaw angle of the head. With respect to the stimulus, escape heading correlates with the elevation of the fish at the onset of motion. Irrespective of the initial orientation, fish can escape in any horizontal direction. In many cases, the centre of mass barely accelerates during Stage 1. However, it does accelerate in the final direction of the escape in other instances, indicating that Stage 1 can serve a propulsive role in addition to its preparatory role for Stage 2. Our findings highlight the importance of large-scale 3D analyses of fast-start manoeuvres of adult fish in uncovering the versatility of fish escape repertoire.
Dioxines, dioxineachtige- en niet dioxineachtige PCB’s in rode aal en schubvis uit Nederlandse binnenwateren : Resultaten van 2017
Leeuwen, S.P.J. van; Hoogenboom, L.A.P. ; Kotterman, M.J.J. - \ 2018
Wageningen : RIKILT Wageningen University & Research (RIKILT-rapport 2018.001) - 39
Intricate links: Displacement, ethno-political conflict, and claim-making to land in Burundi
Tchatchoua-Djomo, Rosine ; Haar, Gemma van der; Dijk, Han van; Leeuwen, Mathijs van - \ 2018
Geoforum (2018). - ISSN 0016-7185
Burundi - Claim-making - Displacement - Ethno-political conflict - Identity - Land disputes - Victimhood
This paper explores claim-making to land in Burundi, where civil war and multiple waves of displacement and return have resulted in complex disputes over land. Zooming in on two different regions, the paper shows that, as people articulate their claims and defend their interests in land disputes, they strategically draw on a diversity of arguments, related to legal categories, notions of belonging and citizenship, social categories derived from (land) policy, but also victimhood, security concerns, and political loyalty. Post-peace agreement land policies play an important role in this, as they instrumentalise war-based categories of identity and victimhood, privileging certain groups of displaced people for political purposes. As we show in two case studies, claim-making tactics follow shifting political discourses and policy changes, as people seek to secure the support of (powerful) allies. A perspective on processes of making claims to land allows us to explore the entanglements between multiple waves of displacement, policy implementation and the instrumentalisation of identities in conflict-affected settings.
A supramolecular approach for liver radioembolization
Spa, Silvia J. ; Welling, Mick M. ; Oosterom, Matthias N. van; Rietbergen, Daphne D.D. ; Burgmans, Mark C. ; Verboom, Willem ; Huskens, Jurriaan ; Buckle, Tessa ; Leeuwen, Fijs W.B. van - \ 2018
Theranostics 8 (2018)9. - ISSN 1838-7640 - p. 2377 - 2386.
Interventional radiology - Nanotechnology - Pre-targeting - Radioembolization - Supramolecular chemistry
Hepatic radioembolization therapies can suffer from discrepancies between diagnostic planning (scout-scan) and the therapeutic delivery itself, resulting in unwanted side-effects such as pulmonary shunting. We reasoned that a nanotechnology-based pre-targeting strategy could help overcome this shortcoming by directly linking pre-interventional diagnostics to the local delivery of therapy. Methods: The host-guest interaction between adamantane and cyclodextrin was employed in an in vivo pre-targeting set-up. Adamantane (guest)-functionalized macro albumin aggregates (MAA-Ad; d = 18 μm) and (radiolabeled) Cy5 and β-cyclodextrin (host)-containing PIBMA polymers (99mTc-Cy50.5CD10PIBMA39; MW ~ 18.8 kDa) functioned as the reactive pair. Following liver or lung embolization with (99mTc)-MAA-Ad or (99mTc)-MAA (controls), the utility of the pre-targeting concept was evaluated after intravenous administration of 99mTc-Cy50.5CD10PIBMA39. Results: Interactions between MAA-Ad and Cy50.5CD10PIBMA39 could be monitored in solution using confocal microscopy and were quantified by radioisotope-based binding experiments. In vivo the accumulation of the MAA-Ad particles in the liver or lungs yielded an approximate ten-fold increase in accumulation of 99mTc-Cy50.5CD10PIBMA39 in those organs (16.2 %ID/g and 10.5 %ID/g, respectively) compared to the control. Pre-targeting with MAA alone was shown to be only half as efficient. Uniquely, for the first time, this data demonstrates that the formation of supramolecular interactions between cyclodextrin and adamantane can be used to drive complex formation in the chemically challenging in vivo environment. Conclusion: The in vivo distribution pattern of the cyclodextrin host could be guided by the pre-administration of the adamantane guest, thereby creating a direct link between the scout-scan (MAA-Ad) and delivery of therapy.
Lability of Nanoparticulate Metal Complexes at a Macroscopic Metal Responsive (Bio)interface : Expression and Asymptotic Scaling Laws
Duval, Jérôme F.L. ; Town, Raewyn M. ; Leeuwen, Herman P. Van - \ 2018
The Journal of Physical Chemistry Part C: Nanomaterials and Interfaces 122 (2018)11. - ISSN 1932-7447 - p. 6052 - 6065.
The lability of metal complexes expresses the extent of the dissociative contribution of the complex species to the flux of metal ions toward a macroscopic metal-responsive (bio)interface, for example, an electrodic sensor or an organism. While the case of molecular ligands is well-established, it is only recently that a definition was elaborated for the lability of metal complexes with nanoparticles (NPs) in aqueous dispersions. The definition includes the thickness of the nonequilibrium reaction layer operational at the (bio)interface and the extent of geometrical exclusion of NPs therefrom. In this work, an explicit expression is derived for the lability of nanoparticulate metal complexes (M-NP) toward a macroscopic reactive (bio)interface. Interpretation accounts for the M-NP chemodynamic properties that depend on the NP size, electrostatics, metal diffusion and dehydration rates, and density of metal binding sites for various NP types, for example, soft/core-shell and hard NPs having volume and surface site distribution, respectively. Computational examples under practical conditions illustrate how these factors jointly determine the remarkable nonmonotonous dependence of the M-NP lability parameter on the NP size. The analysis is supported by the formulation of asymptotic scaling laws clarifying how local M-NP dissociation dynamics affect the lability parameter for M-NP complexes at the scale of the macroscopic (bio)interface.
Visual soil evaluation : reproducibility and correlation with standard measurements
Leeuwen, Maricke M.W.J. van; Heuvelink, Gerard B.M. ; Wallinga, Jakob ; Boer, Imke J.M. de; Dam, Jos C. van; Essen, Everhard A. van; Moolenaar, Simon W. ; Verhoeven, Frank P.M. ; Stoorvogel, Jetse J. ; Stoof, Cathelijne R. - \ 2018
Soil & Tillage Research 178 (2018). - ISSN 0167-1987 - p. 167 - 178.
Reproducibility - Soil quality assessment - Visual soil evaluation
Visual soil evaluation (VSE) is a simple and fast method to assess soil quality in situ, and is becoming increasingly popular. Besides soil structure assessment, also other soil properties can be assessed such as grass cover, roots and earthworms. Yet, the full set of visual observations has not been properly evaluated for reproducibility and correlation with standard field or laboratory measurements, for several soil types. The objectives of this study were therefore to evaluate the reproducibility and the correlation of visual observations with closely related field or laboratory measurements. We used quantitative visual observations where possible, to enhance objectivity of VSE. The reproducibility and correlation of visual observations with standard measurements was evaluated for three soil types (sand, peat and clay) in the North Friesian Woodlands, The Netherlands. Reproducibility of quantitative visual observations was tested by comparing observations made by farmers and soil scientists, on the same soils. A linear mixed-effect model indicated that for all quantitative visual observations except for the depth of soil compaction, subjectivity due to the observers’ background (farmer or soil scientist) had no significant effect on the observations. For assessment of relative soil quality differences between sites, the results suggested that a single observer can make the visual observations, when assessing the fraction largest soil structural elements, earthworms, gley mottles and the depth of soil compaction. Spearman's rank correlation coefficients indicated that visual observations of grass cover, root count, maximum rooting depth and the fraction largest soil structural elements correlated significantly with closely related field or laboratory measurements regardless of soil type. Maximum rooting depth, root count, soil colour, the fraction largest soil structural elements, and the degree of soil compaction only significantly correlated with field or laboratory measurements for specific soil types. Analyses showed that the correlation of visual observations with standard measurements were soil type dependent, suggesting that the evaluation of soil quality should also be soil type dependent.
Introduction to the Alonso’s Five Bells : Insights for Spatial Inequality and Population Decline Special Issue
Leeuwen, Eveline S. van; Franklin, Rachel S. - \ 2018
International Regional Science Review 41 (2018)2. - ISSN 0160-0176 - p. 131 - 133.
For Whom the Bells Toll : Alonso and a Regional Science of Decline
Franklin, Rachel S. ; Leeuwen, Eveline S. van - \ 2018
International Regional Science Review 41 (2018)2. - ISSN 0160-0176 - p. 134 - 151.
population decline - regional science - spatial inequality
In his presidential address to the Regional Science Association over thirty years ago, William Alonso presented the case for “Five Bell Shapes in Development” and argued that “the developed countries will enter fully in to the realm of the right-hand tail of these curves” (p. 16) and that this transition might result in several surprises. He proposed, therefore, that we should study the right tail of these “curves” as well as interactions among them. Much of what Alonso suggested has come to pass, although his prognostications were not always exact. And although he touched on several issues of relevance to regional scientists, the discipline has been slow to move away from a growth-centered paradigm. The strength of regional science—the capacity to consider economic, demographic, and geographical aspects of an issue simultaneously—has yet to be focused on some of the “right-hand” challenges that have arisen, population loss, for example. In this article, we provide a review of regional science research within the context of Alonso’s five bells and hypothesize how Alonso’s propositions might differ in today’s world. We then focus more specifically on one particular area: population loss. Using these examples allows us to highlight how regional science might contribute to the conceptualization of “right-hand tail” development challenges, especially where theory, issues of spatial scale, and interregional dependencies are concerned.
Biomechanics of swimming in developing larval fish
Voesenek, Cees J. ; Muijres, Florian T. ; Leeuwen, Johan L. Van - \ 2018
Journal of Experimental Biology 221 (2018)1. - ISSN 0022-0949
Cost of transport - Energetics of locomotion - Escape manoeuvre - Fluid dynamics - Muscle development - Zebrafish

Most larvae of bony fish are able to swim almost immediately after hatching. Their locomotory system supports several vital functions: fish larvae make fast manoeuvres to escape from predators, aim accurately during suction feeding and maymigrate towards suitable future habitats. Owing to their small size and low swimming speed, larval fish operate in the intermediate hydrodynamic regime, which connects the viscous and inertial flow regimes. They experience relatively strong viscous effects at low swimming speeds, and relatively strong inertial effects at their highest speeds. As the larvae grow and increase swimming speed, a shift occurs towards the inertial flow regime. To compensate for sizerelated limitations on swimming speed, fish larvae exploit high tail beat frequencies at their highest speeds, made possible by their low body inertia and fast neuromuscular system. The shifts in flow regime and body inertia lead to changing functional demands on the locomotory system during larval growth. To reach the reproductive adult stage, the developing larvae need to adjust to and perform the functions necessary for survival. Just after hatching, many fish larvae rely on yolk and need to develop their feeding systems before the yolk is exhausted. Furthermore, the larvae need to develop and continuously adjust their sensory, neural and muscular systems to catch prey and avoid predation. This Review discusses the hydrodynamics of swimming in the intermediate flow regime, the changing functional demands on the locomotory system of the growing and developing larval fish, and the solutions that have evolved to accommodate these demands.

Discrimination of processing grades of olive oil and other vegetable oils by monochloropropanediol esters and glycidyl esters
Yan, Jing ; Oey, Sergio B. ; Leeuwen, Stefan P.J. van; Ruth, Saskia M. van - \ 2018
Food Chemistry 248 (2018). - ISSN 0308-8146 - p. 93 - 100.
Authenticity - Fraud - GC–MS/MS - Processing contaminants
In this study, the processing derived contaminants 2- and 3-monochloropropanediol (2- and 3-MCPD) esters and glycidyl esters (GEs) were analysed in 84 oil samples by GC–MS/MS for the discrimination of processing grades of olive oils as a potential authentication tool. Concentrations of 2- and 3-MCPD esters and GEs varied in the ranges 0–6 mg/kg, 0–1.5 mg/kg, and 0–1 mg/kg oil, respectively. The concentrations of the three compounds in lower grade olive oils were significantly higher (P <.001) than that in EVOO. A similar difference was observed for other refined and cold-pressed vegetable oils. The limit of fraud detection of lower grade oils in EVOO was 2% when using 3-MCPD esters, 5% for 2-MCPD esters, and 13–14% for GEs based on calculations of virtual mixtures of the current sample set. Especially the MCPD esters appear very specific and promising for the detection of lower processing grade oils in EVOO.
Residents’ preferences for cultural services of the landscape along the urban–rural gradient
Zhou, Ting ; Koomen, Eric ; Leeuwen, Eveline S. van - \ 2018
Urban Forestry and Urban Greening 29 (2018). - ISSN 1618-8667 - p. 131 - 141.
Cultural services - Landscape valuation - Maastricht - Urban–rural gradient
Cultural services of the landscape contribute to a higher quality of life. The provision of these services differs along the urban–rural gradient, as does their appreciation by local residents. This paper investigates residents’ preferences for cultural services along the urban–rural gradient through a map-based survey in and around the Dutch city of Maastricht. We focus on the importance of location in explaining these preferences, distinguishing the location of residents (relative to the preferred landscape units) and the location of landscape units (relative to their positions on the urban–rural gradient). The study shows that residents prefer nearby locations for all distinguished cultural services. Locations’ valuation along the urban–rural gradient, however, differs by service type: for cultural heritage locations near the city centre are preferred, while outdoor recreation and sports and passive enjoyment of green landscapes are enjoyed more in rural areas. When considering the spatial distribution of the land-use types that provide these services, we further find that people prefer green areas closer to the city for outdoor recreation and sports and passive enjoyment of green landscapes. The results illustrate the heterogeneity of people's preferences for cultural services along the urban–rural gradient beyond the distance from their residences. We recommend policy makers to take the urban–rural gradient into account when valuating landscape units, and in particularly the importance of green landscape units close to the city for different cultural services.
A comparison of UVb compact lamps in enabling cutaneous vitamin D synthesis in growing bearded dragons
Diehl, J.J.E. ; Baines, F.M. ; Heijboer, A.C. ; Leeuwen, J.P. van; Kik, M. ; Hendriks, W.H. ; Oonincx, D.G.A.B. - \ 2018
Journal of Animal Physiology and Animal Nutrition 102 (2018)1. - ISSN 0931-2439 - p. 308 - 316.
25(OH)D - Lizard - Pogona vitticeps - Reptile - Ultraviolet light - Vitamin D - Vitamin D metabolites

The effect of exposure to different UVb compact lamps on the vitamin D status of growing bearded dragons (Pogona vitticeps) was studied. Forty-two newly hatched bearded dragons (<24 h old) were allocated to six treatment groups (n = 7 per group). Five groups were exposed to different UVb compact lamps for two hours per day, with a control group not exposed to UVb radiation. At 120 days of age, blood samples were obtained and concentrations of 25(OH)D3, Ca, P and uric acid were determined. In addition, plasma 25(OH)D3 concentration was determined in free-living adult bearded dragons to provide a reference level. Only one treatment resulted in elevated levels of 25(OH)D3 compared to the control group (41.0 ± 12.85 vs. 2.0 ± 0.0 nmol/L). All UVb-exposed groups had low 25(OH)D3 plasma levels compared to earlier studies on captive bearded dragons as well as in comparison with the free-living adult bearded dragons (409 ± 56 nmol/L). Spectral analysis indicated that all treatment lamps emitted UVb wavelengths effective for some cutaneous vitamin D synthesis. None of these lamps, under this regime, appeared to have provided a sufficient UVb dose to enable synthesis of plasma 25(OH)D3 levels similar to those of free-living bearded dragons in their native habitat.

New and emerging postharvest diseases in pome fruit in the Netherlands
Wenneker, M. ; Pham, K.T.K. ; Leeuwen, P.J. van; Schaik, A.C.R. van; Köhl, J. - \ 2017
In: Book of abstracts IV International Symposium on Postharvest Pathology. - - p. 29 - 29.
Emerging and threatening postharvest diseases in pome fruit in the Netherlands
Wenneker, M. ; Pham, K.T.K. ; Leeuwen, P.J. van - \ 2017
In: Program and abstracts 11th International IOBC-WPRS Workshop on Pome Fruit Diseases. - IOBC - p. 58 - 58.
Emerging and threatening postharvest diseases in pome fruit in the Netherlands
Wenneker, M. ; Pham, K.T.K. ; Leeuwen, P.J. van - \ 2017
Data from: Mechanisms of ovipositor insertion and steering of a parasitic wasp
Cerkvenik, U. ; Straat, Bram van de; Gussekloo, S.W.S. ; Leeuwen, J.L. van - \ 2017
ovipositor kinematics - buckling avoidance - spatial probing - minimally inavasive probe - Diachasmimorpha longicaudata
Check title to add to marked list
<< previous | next >>

Show 20 50 100 records per page

Please log in to use this service. Login as Wageningen University & Research user or guest user in upper right hand corner of this page.