Staff Publications

Staff Publications

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    '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.

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    Genetic basis of falling risk susceptibility in the UK Biobank Study
    Trajanoska, Katerina ; Seppala, Lotta J. ; Medina-Gomez, Carolina ; Hsu, Yi Hsiang ; Zhou, Sirui ; Schoor, Natasja M. van; Groot, Lisette C.P.G.M. de; Karasik, David ; Richards, J.B. ; Kiel, Douglas P. ; Uitterlinden, Andre G. ; Perry, John R.B. ; Velde, Nathalie van der; Day, Felix R. ; Rivadeneira, Fernando - \ 2020
    Communications Biology 3 (2020). - ISSN 2399-3642

    Both extrinsic and intrinsic factors predispose older people to fall. We performed a genome-wide association analysis to investigate how much of an individual’s fall susceptibility can be attributed to genetics in 89,076 cases and 362,103 controls from the UK Biobank Study. The analysis revealed a small, but significant SNP-based heritability (2.7%) and identified three novel fall-associated loci (Pcombined ≤ 5 × 10−8). Polygenic risk scores in two independent settings showed patterns of polygenic inheritance. Risk of falling had positive genetic correlations with fractures, identifying for the first time a pathway independent of bone mineral density. There were also positive genetic correlations with insomnia, neuroticism, depressive symptoms, and different medications. Negative genetic correlations were identified with muscle strength, intelligence and subjective well-being. Brain, and in particular cerebellum tissue, showed the highest gene expression enrichment for fall-associated variants. Overall, despite the highly heterogenic nature underlying fall risk, a proportion of the susceptibility can be attributed to genetics.

    CAPICE: A computational method for Consequence-Agnostic Pathogenicity Interpretation of Clinical Exome variations
    Li, Shuang ; Velde, K.J. Van Der; Ridder, Dick De; Dijk, Aalt D.J. Van; Soudis, Dimitrios ; Zwerwer, Leslie R. ; Deelen, Patrick ; Hendriksen, Dennis ; Charbon, Bart ; Gijn, Marielle E. Van; Abbott, Kristin ; Sikkema-Raddatz, Birgit ; Diemen, Cleo C. Van; Kerstjens-Frederikse, Wilhelmina S. ; Sinke, Richard J. ; Swertz, Morris A. - \ 2020
    Genome Medicine 12 (2020)1. - ISSN 1756-994X
    Allele frequency - Clinical genetics - Exome sequencing - Genome diagnostics - Machine learning - Molecular consequence - Variant pathogenicity prediction

    Exome sequencing is now mainstream in clinical practice. However, identification of pathogenic Mendelian variants remains time-consuming, in part, because the limited accuracy of current computational prediction methods requires manual classification by experts. Here we introduce CAPICE, a new machine-learning-based method for prioritizing pathogenic variants, including SNVs and short InDels. CAPICE outperforms the best general (CADD, GAVIN) and consequence-type-specific (REVEL, ClinPred) computational prediction methods, for both rare and ultra-rare variants. CAPICE is easily added to diagnostic pipelines as pre-computed score file or command-line software, or using online MOLGENIS web service with API. Download CAPICE for free and open-source (LGPLv3) at

    Long-term effects of folic acid and vitamin-B12 supplementation on fracture risk and cardiovascular disease : Extended follow-up of the B-PROOF trial
    Oliai Araghi, Sadaf ; Kiefte-de Jong, Jessica C. ; Dijk, Suzanne C. van; Swart, Karin M.A. ; Ploegmakers, Kim J. ; Zillikens, M.C. ; Schoor, Natasja M. van; Groot, Lisette C.P.G.M. de; Lips, Paul ; Stricker, Bruno H. ; Uitterlinden, André G. ; Velde, Nathalie van der - \ 2020
    Clinical Nutrition (2020). - ISSN 0261-5614
    B-vitamins - Cardiovascular disease - Fracture - Long-term follow-up

    Background & aims: In the initial B-proof, we found inconsistent results of B vitamin supplementation. However, the debate regarding the effects of B vitamins on age-related diseases continues. Therefore, our aim was to investigate the long-term effects (5–7 years follow-up) of an intervention with folic acid and vitamin-B12 supplementation on fracture and cardiovascular disease risk. Methods: Extended follow-up of the B-PROOF trial, a multi-center, double-blind randomized placebo-controlled trial designed to assess the effect of 2–3 years daily supplementation with folic acid (400 μg) and vitamin-B12 (500 μg) versus placebo (n = 2,919). Primary outcome was verified self-reported fracture incidence and secondary outcomes were self-reported cardiovascular endpoints, which were collected through a follow-up questionnaires Proportional hazard analyses was used for the effect of the intervention on risk of fracture(s) and logistic regression for the effect of the intervention on risk of cardiovascular disease. Results: A total of 1,298 individuals (44.5%) participated in the second follow-up round with median of 54 months [51–58], (n = 662 and n = 636, treatment versus placebo group). Median age at baseline was 71.0 years [68.0–76.0] for both groups. No effect was observed of the intervention on osteoporotic fracture or any fracture risk after a follow-up (HR: 0.99, 95% CI: 0.62–1.59 and HR: 0.77; 95% CI: 0.50–1.19, respectively), nor on cardiovascular or cerebrovascular disease risk (OR: 1.05; 95%CI: 0.80–1.44 and OR: 0.85; 95%CI: 0.50–1.45, respectively). Potential interaction by baseline homocysteine concentration was observed for osteoporotic- and any fracture (p = 0.10 and 0.06 respectively), which indicated a significantly lower risk of any fracture in the treatment group with higher total homocysteine concentrations (>15.1 μmol/l). No age-dependent effects were present. Conclusions: This study supports and extends previous null-findings of the B-PROOF trial and shows that supplementation of folic acid and vitamin-B12 has no effect on fracture risk, nor on cardiovascular disease in older individuals over a longer follow-up period. However, B-vitamin supplementation may be beneficial in reducing fractures in individuals with high total homocysteine concentrations, a finding which needs to be replicated.

    Pesticides in feed materials of plant origin : Application of processing factors
    Meijer, Nathan ; Velde-Koerts, Trijntje van der; Egmond, Harry van; Bikker, Paul - \ 2020
    Wageningen : Wageningen Food Safety Research (WFSR-report / Wageningen Food Safety Research 2019.016) - 41
    The influence of a front-of-pack nutrition label on product reformulation : A ten-year evaluation of the Dutch Choices programme
    Bend, Daphne L.M. van der; Jansen, Léon ; Velde, Gerben van der; Blok, Vincent - \ 2020
    Food Chemistry: X 6 (2020). - ISSN 2590-1575
    Dutch Choices Logo - Front-of-Pack nutrition labelling - Product nutrient composition - Product reformulation

    Front-of-pack (FoP) labels are regarded as helpful tools to stimulate healthier product reformulation as they are based on nutrient criteria that products should comply with in order to obtain the label. Some FoP labelling programs revise criteria periodically. This is the first study investigating the impact of criteria revisions on product compositions over time. Nutrient contents of 4,343 products, including 27 basic and non-basic product (sub) categories with the Dutch Choices Logo were analysed between 2006 and 2016. The number of labelled products increased over time. Sodium and trans-fat contents reduced significantly in 10 and 11 product categories, respectively. Energy, saturated fat and added sugar decreased significantly whilst fibre increased in 4–6 product categories. Overall, labelled products had healthier compositions and more favourable trends in nutrient content compared with products generally on the Dutch market. The results of this study suggest an important role for FoP labels in product reformulation.

    Supercritical fluid chromatography as a rapid single-step method for the determination of mineral oil saturated and aromatic hydrocarbons in purified mineral oils for food and cosmetics applications
    Garcia-Cicourel, Alan Rodrigo ; Velde, Bas van de; Roskam, Gerry ; Janssen, Hans-Gerd - \ 2020
    Journal of Chromatography. A, Including electrophoresis and other separation methods 1614 (2020). - ISSN 0021-9673
    Mineral oil hydrocarbons are used in the consumer goods sector for the elaboration of a wide range of foods and cosmetics. Traditional methods for determining their levels and composition are time consuming and laborious, besides requiring complex instrumentation. Here a simple and fast method was developed that uses columns packed with silver-modified silica in supercritical fluid chromatography with flame ionization and UV detection (SFC-FID/UV) for the determination of mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH) in purified mineral oil samples. The method requires no sample preparation apart from dilution. Direct quantification of MOSH and MOAH was possible for samples with MOSH/MOAH ratios around one. For other samples deconvolution of the MOSH and MOAH humps in the FID chromatogram using the UV signal was needed since baseline separation of the two fractions could not be obtained. Validation of the method performance showed an excellent linearity (R2 > 0.9995) in the range of concentrations tested (2.5–100 mgmL−1) and a better repeatability than the standard methods (<5%). MOAH detection limits were better than 0.36% MOAH, which makes the method sufficiently sensitive for analysis of all but the highest purity mineral oils. The proposed SFC-FID/UV method was suitable for the analysis of mineral oils with viscosities and molecular weights below approximately 56 mm2s−1 and 450 gmol−1. The quantitative results of the new method were not statistically significantly different from those obtained with the standard SPE-GC-FID method where the new method has the advantages of a better repeatability, simpler operation and a significantly shortened analysis time. This new method could potentially also be used for the analysis of mineral oil contaminations in consumer products such as foods. However, in this case additional sample clean-up and preconcentration steps are needed for reducing matrix interferences from e.g. triglycerides and olefins and for improving the detection limits.
    Impact of the invasive alien topmouth gudgeon (Pseudorasbora parva) and its associated parasite Sphaerothecum destruens on native fish species
    Spikmans, Frank ; Lemmers, Pim ; Camp, Huub J.M. op den; Haren, Emiel van; Kappen, Florian ; Blaakmeer, Anko ; Velde, Gerard van der; Langevelde, Frank van; Leuven, Rob S.E.W. ; Alen, Theo A. van - \ 2020
    Biological Invasions 22 (2020)2. - ISSN 1387-3547 - p. 587 - 601.
    Biodiversity threat - eDNA - Gasterosteus aculeatus - Leucaspius delineatus - Pathogen - Pungitius pungitius

    The Asian cyprinid Pseudorasbora parva is considered to be a major threat to native fish communities and listed as an invasive alien species of European Union concern. Our study aims to gain evidence-based knowledge on the impact of both P. parva and its parasite Sphaerothecum destruens on native fish populations by analysing fish assemblages and body condition of individuals of native fish species in floodplain water bodies that were invaded and uninvaded by P. parva. We explored the use of environmental DNA (eDNA) techniques to detect S. destruens. Prevalence of S. destruens in native fish species was assessed. Fish samplings showed significantly negative correlations between the abundance of P. parva and the native Leucaspius delineatus, and Pungitius pungitius and three biodiversity indices of the fish assemblages (Simpson’s diversity index, Shannon–Wiener index and evenness). Contrastingly, the abundances of the native Gasterosteus aculeatus and P. parva were positively related. In nearly all isolated water bodies with P. parva, this species is outnumbering native fish species. No effect of P. parva presence was found on body condition of native fish species. Sphaerothecum destruens was demonstrated to occur in both P. parva and G. aculeatus. Gasterosteus aculeatus is suggested to be an asymptomatic carrier that can aid the further spread of S. destruens. Analysis of eDNA proved to be a promising method for early detection of S. destruens, here showing that S. destruens presence coincided with P. parva presence. The ongoing invasion of both P. parva and S. destruens is predicted to pose a significant risk to native fish communities.

    Do Vitamin D Level and Dietary Calcium Intake Modify the Association Between Loop Diuretics and Bone Health?
    Oliai Araghi, Sadaf ; Kiefte-de Jong, Jessica C. ; Trajanoska, Katerina ; Koromani, Fjorda ; Rivadeneira, Fernando ; Zillikens, Carola M. ; Schoor, Natasja M. van; Groot, Lisette C.P.G.M. de; Ikram, M.A. ; Uitterlinden, André G. ; Stricker, Bruno H. ; Velde, Nathalie van der - \ 2020
    Calcified Tissue International 106 (2020)2. - ISSN 0171-967X - p. 104 - 114.
    Bone geometry - Bone mineral density - Loop diuretics - Trabecular Bone Score

    Loop diuretics (LD) may affect bone health by inhibiting renal calcium reuptake. However, whether vitamin D status and dietary calcium intake modify the association between LD and bone outcome is unclear. Therefore, this study aimed to evaluate whether vitamin D level or calcium intake modify the association between LD and various indices of bone health including bone mineral density (BMD) and Trabecular Bone Score (TBS). From The Rotterdam Study, a prospective population-based cohort study, we used data from 6990 participants aged > 45 year with a DXA scan (2002–2008), 6908 participants with femoral neck (FN)-BMD, 6677 participants with lumbar spine (LS)-BMD and 6476 participants with LS-TBS measurements. Use of LD was available from pharmacy dispensing records. Vitamin D (25(OH)D) level was measured in serum, and dietary calcium intake was measured with a validated food frequency questionnaire. Almost eight percent of the participants used LD. The association between LD (past-users compared to never-users) and LS-TBS was significantly different by 25(OH)D concentrations (P for interaction = 0.04). A significantly lower LS-TBS among LD past-users was observed for 25(OH)D ≥ 50 nmol/l compared to ≤ 20 and 20–50 nmol/l (β = − 0.036, 95% CI − 0.060; − 0.013 vs. β = − 0.012, 95% CI − 0.036; 0.013 and β = − 0.031, 95% CI − 0.096; 0.034, respectively). However, no other significant effect modification by 25(OH)D and dietary calcium intake was found in the associations between LD use and bone health outcomes (P-interaction > 0.13). This study suggests that the association between LD use and indices of bone health is not consistently modified by vitamin D or dietary calcium intake.

    Quality Improvement in African Food Supply Chains: Determinants of Farmer Performance
    Tefera, Delelegne Abera ; Bijman, Jos ; Slingerland, Maja ; Velde, Gerben van der; Omta, Onno - \ 2020
    European Journal of Development Research 32 (2020)1. - ISSN 0957-8811 - p. 152 - 175.
    Economics of quality - Ethiopia - Institutional arrangement - Malt barley - Quality-upgrading - Smallholders

    The integration of smallholders in modern value chains in sub-Saharan Africa is an important pathway for improving income and farmer livelihoods. Connected to demographic shifts, rapid urbanization, and the emergence of a middle class, there is a demand for higher product quality. In order to access these modern markets, smallholders need to enhance the quality of their products. However, factors that determine smallholders’ decision to invest in quality upgrading are not well understood. Using cross-sectional data from the Ethiopian barley sector, we analyse the factors that explain smallholders’ decision to improve quality. We find that socioeconomic, institutional and market factors affect the decision to improve quality. Our study contributes to the understanding of the determinants of quality upgrading at the micro-level of the economics of quality production, and thus of rural development.

    B-vitamins and body composition: integrating observational and experimental evidence from the B-PROOF study
    Oliai Araghi, Sadaf ; Braun, Kim V.E. ; Velde, Nathalie van der; Dijk, Suzanne C. van; Schoor, Natasja M. van; Zillikens, M.C. ; Groot, Lisette C.P.G.M. de; Uitterlinden, Andre G. ; Stricker, Bruno H. ; Voortman, Trudy ; Kiefte-de Jong, Jessica C. - \ 2020
    European Journal of Nutrition 59 (2020). - ISSN 1436-6207 - p. 1253 - 1262.
    BMI - Body composition - Effect of vitamin B12 and folic acid on obesity - Fat (Free) mass - Vitamin B12 and folic acid

    Purpose: Higher folate and vitamin-B12 have been linked to lower risk of overweight. However, whether this is a causal effect of these B-vitamins on obesity risk remains unclear and evidence in older individuals is scarce. This study aimed to assess the role of B-vitamin supplementation and levels on body composition in older individuals. Methods: A double-blind, randomized controlled trial in 2919 participants aged ≥ 65 years with elevated homocysteine levels. The intervention comprised a 2-year supplementation with a combination of folic acid (400 µg) and vitamin B12 (500 µg), or with placebo. Serum folate, vitamin-B12, active vitamin-B12 (HoloTC), methylmalonic acid (MMA), and anthropometrics were measured at baseline and after 2 years of follow-up. Dietary intake of folate and vitamin-B12 was measured at baseline in a subsample (n = 603) using a validated food-frequency questionnaire. Fat mass index (FMI) and fat-free mass index (FFMI) were assessed with Dual Energy X-ray absorptiometry (DXA). Results: Cross-sectional analyses showed that a 1 nmol/L higher serum folate was associated with a 0.021 kg/m 2 lower BMI (95% CI − 0.039; − 0.004). Higher HoloTC (per pmol/L log-transformed) was associated with a 0.955 kg/m 2 higher FMI (95% CI 0.262; 1.647), and higher MMA (per μgmol/L) was associated with a 1.108 kg/m 2 lower FMI (95% CI − 1.899; − 0.316). However, random allocation of B-vitamins did not have a significant effect on changes in BMI, FMI or FFMI during 2 years of intervention. Conclusions: Although observational data suggested that folate and vitamin B12 status are associated with body composition, random allocation of a supplement with both B-vitamins combined versus placebo did not confirm an effect on BMI or body composition.

    Environmental footprint family to address local to planetary sustainability and deliver on the SDGs
    Vanham, Davy ; Leip, Adrian ; Galli, Alessandro ; Kastner, Thomas ; Bruckner, Martin ; Uwizeye, Aimable ; Dijk, Kimo Van; Ercin, Ertug ; Dalin, Carole ; Brandão, Miguel ; Bastianoni, Simone ; Fang, Kai ; Leach, Allison ; Chapagain, Ashok ; Velde, Marijn Van Der; Sala, Serenella ; Pant, Rana ; Mancini, Lucia ; Monforti-ferrario, Fabio ; Carmona-garcia, Gema ; Marques, Alexandra ; Weiss, Franz ; Hoekstra, Arjen Y. - \ 2019
    Science of the Total Environment 693 (2019). - ISSN 0048-9697
    The number of publications on environmental footprint indicators has been growing rapidly, but with limited efforts to integrate different footprints into a coherent framework. Such integration is important for comprehensive understanding of environmental issues, policy formulation and assessment of trade-offs between different environmental concerns. Here, we systematize published footprint studies and define a family of footprints that can be used for the assessment of environmental sustainability. We identify overlaps between different footprints and analyse how they relate to the nine planetary boundaries and visualize the crucial information they provide for local and planetary sustainability. In addition, we assess how the footprint family delivers on measuring progress towards Sustainable Development Goals (SDGs), considering its ability to quantify environmental pressures along the supply chain and relating them to the water-energy-food-ecosystem (WEFE) nexus and ecosystem services. We argue that the footprint family is a flexible framework where particular members can be included or excluded according to the context or area of concern. Our paper is based upon a recent workshop bringing together global leading experts on existing environmental footprint indicators.
    Palaeogeografisch veenonderzoek voor archeologische toepassingen
    Wallinga, Jakob ; Velde, Ype van der; Quik, Cindy ; Beek, Roy van - \ 2019
    Alles wat bijen nodig hebben, is een B&B
    Groot, Arjen de - \ 2019
    Comparing saliva and urine samples for measuring breastmilk intake with the deuterium oxide dose-to-mother technique among children 2-4 months old
    Matsiko, Eric ; Hulshof, Paul J.M. ; Velde, Laura Van Der; Kenkhuis, Marlou Floor ; Tuyisenge, Lisine ; Melse-Boonstra, Alida - \ 2019
    The British journal of nutrition (2019). - ISSN 0007-1145
    Breastmilk intake - Deuterium oxide dose-to-mother technique - Doubly labelled water - Maternal energy expenditure - Saliva and urine samples

    Saliva and urine are the two main body fluids sampled when breastmilk intake is measured with the deuterium oxide dose-to-mother technique. However, these two body fluids may generate different estimates of breastmilk intake due to differences in isotope enrichment. Therefore, we aimed to assess how the estimated amount of breastmilk intake differs when based on saliva and urine samples and to explore whether the total energy expenditure of the mothers is related to breastmilk output. We used a convenience sample of 13 pairs of mothers and babies aged 2 to 4 months, who were exclusively breastfed and apparently healthy. To assess breastmilk intake, we administered doubly labelled water to the mothers, and collected saliva samples from them, while simultaneously collecting both saliva and urine from their babies over a 14-day period. IRMS was used to analyze the samples for deuterium and oxygen-18 enrichments. Mean breastmilk intake based on saliva samples was significantly higher than that based on urine samples (854.5g/day vs. 812.8g/day, p=0.029). This can be attributed to slightly higher isotope enrichments in saliva and to a poorer model fit for urine samples as indicated by a higher square root of the mean square error (14.6 vs. 10.4 mg/kg, p=0.001). Maternal energy expenditure was not correlated with breastmilk output. Our study suggests that saliva sampling generates slightly higher estimates of breastmilk intake and is more precise as compared to urine and that maternal energy expenditure does not influence breastmilk output.

    State updating of root zone soil moisture estimates of an unsaturated zone metamodel for operational water resources management
    Pezij, Michiel ; Augustijn, Denie C.M. ; Hendriks, Dimmie M.D. ; Weerts, Albrecht H. ; Hummel, Stef ; Velde, Rogier van der; Hulscher, Suzanne J.M.H. - \ 2019
    Journal of Hydrology 4 (2019). - ISSN 0022-1694
    Data assimilation - Ensemble Kalman filter - Hydrological modelling - Metamodelling - Remote sensing - SMAP - Soil moisture

    Combining metamodels with data assimilation schemes allows the incorporation of up-to-date information in metamodels, offering new opportunities for operational water resources management. We developed a data assimilation scheme for the unsaturated zone metamodel MetaSWAP using OpenDA, which is an open source data assimilation framework. A twin experiment showed the feasibility of applying an Ensemble Kalman filter as a data assimilation method for updating metamodels. Furthermore, we assessed the accuracy of root zone soil moisture model estimates when assimilating the regional SMAP L3 Enhanced surface soil moisture product. The model accuracy is assessed using in situ soil moisture measurements collected at 12 locations in the Twente region, the Netherlands. Although the accuracy of the model estimates does not improve in terms of correlation coefficient, the accuracy does improve in terms of Root Mean Square Error and bias. Therefore, the assimilation of surface soil moisture observations has value for updating root zone soil moisture model estimates. In addition, the accuracy of the model estimates improves on both regional and local spatial scales. The increasing availability of remotely sensed soil moisture data will lead to new possibilities for integrating metamodelling and data assimilation in operational water resources management. However, we expect that significant investments in computational capacities are necessary for effective implementation in decision-making.

    Entrepreneurial orientation as the basis for resource orchestration, business resilience and family livelihood in turbulent, resource-scarce contexts : a study among non-farm entrepreneurs in Ethiopia
    Saad, Muhammedamin Hussen - \ 2019
    Wageningen University. Promotor(en): S.W.F. Omta, co-promotor(en): J.L.F. Hagelaar; G. van der Velde. - Wageningen : Wageningen University - ISBN 9789463950848 - 237

    Small and medium enterprises (SMEs) are viewed as key to family livelihood and poverty reduction in developing countries, but their resilience in such turbulent, resource-scarce contexts depends on the strategic actions taken by entrepreneurs in acquiring, bundling, and leveraging scarce resources. These strategic actions and practices are categorized, in this thesis, as resource orchestration (RO) processes. From a strategic entrepreneurship perspective, the firm’s entrepreneurial orientation (EO) is a key driver of these orchestration processes. However, business resilience is not an end goal in itself and must be linked to family livelihood, thus requiring the investigation of supportive survival strategies used in this context. This thesis, therefore, focuses on advancing the debates on business resilience, resource orchestration processes driven by EO, and survival strategies that support non-farm entrepreneurs in improving family livelihood in the context of a developing country (i.e., Ethiopia).

    The results of a survey of 408 non-farm entrepreneurs show that EO drives resource orchestration processes and explains the differences between firms’ resilience (Chapters 4 and 5). Supportive strategies are also identified that confirm entrepreneurial efforts to transform business resilience into a contribution to family livelihood (Chapter 6). This empirical research is based on two preparatory studies: conducting an extensive literature review of the state of the art of SME-related resilience studies (Chapter 2), building, and testing a resilience measurement instrument in resource-scarce disruptive environments (Chapter 3). Both studies contribute new insights to the resilience literature.

    This thesis informs theory and practice related to increasing the business resilience of SMEs and turning this resilience into a family livelihood in resource-scarce disruptive business environments. This thesis makes empirical and theoretical contributions that critically engage with these issues in the context of developing countries. Based on the results, this thesis suggests further research and discusses implications for entrepreneurs, researchers, policymakers, and business practitioners.

    Monitoring agricultural field trafficability using Sentinel-1
    Carranza, Coleen ; Benninga, Harm J. ; Velde, Rogier van der; Ploeg, Martine van der - \ 2019
    Agricultural Water Management 224 (2019). - ISSN 0378-3774
    Agriculture - Decoupling - Kernel density estimation - Sentinel-1 - Soil moisture - Trafficability

    The use of heavy mobile machinery in agriculture for tillage and harvesting is now indispensable since it facilitates farming over large areas. However, one of the impacts of regular and prolonged use of heavy mobile machinery is soil compaction. To help minimize this harmful effect, trafficability of agricultural fields needs to be determined. Soil moisture acts as one of the dominant controls for field trafficability. Therefore satellites such as Sentinel-1, which is one source of spatio-temporal soil moisture information, could be useful in assessing trafficable conditions. One limitation of satellite-derived soil moisture is that only the upper surface layer is mapped. In this study, we determined the feasibility of Sentinel-1 surface soil moisture to monitor trafficability over 2016–2017. We first determined coupled conditions when surface soil moisture is a good indicator for values at the subsurface. We applied a probabilistic approach to determine trafficability using extensive in situ measurements of penetration resistance and surface soil moisture over a variety of crops. Trafficability is expressed as the probability that penetration resistance will exceed a threshold, for a given soil moisture value. Furthermore, we investigated the variability encountered from these measurements to gain insights on other temporal controls. Our results show coupled conditions for soil moisture ≥0.19 cm3 cm−3 and there is an almost 1:1 correspondence between surface and subsurface values. For decoupled conditions, values at the subsurface can be two times more than the surface. An increase in penetration resistance variability coincided with the maturity of crops for cultivated fields. Aside from soil moisture, root growth may have a significant impact on the temporal variability of soil's penetration resistance. The status of trafficability can be monitored through the high temporal resolution of Sentinel-1. However, aggregation to coarser resolutions maybe necessary as its original 10 m resolution may be suboptimal, based on validation against in situ measurements. Days favorable for traffic were observed in early spring. This information can aid farmers in the timing of tillage activities or for water managers in deciding to adjust water levels to meet agricultural demands.

    Nudging physical activity in offices
    Meiden, Iris van der; Kok, Herman ; Velde, Gerben van der - \ 2019
    Journal of Facilities Management (2019). - ISSN 1472-5967
    Experiment - Health benefits - Nudging - Observations - Office environment - Stair use

    Purpose: This paper aims to investigate whether and why nudging interventions in an office environment are effective to stimulate stair use of employees. Design/methodology/approach: This paper is based on a pre-test/post-test case study design at the headquarters of a Dutch online retailer. Observations were conducted to test the impact of two nudge interventions, being footprints and posters, on employees’ stair use in two consecutive pre-test/post-test weeks. An online survey questionnaire was used to assess employees’ overall experience with the nudging interventions after the fifth and again neutral week. Findings: A total of 14,357 observations were recorded during five weeks. This research shows that footprints as nudging intervention significantly increase stair use of employees, and after removal, significantly decrease stair use again. Moreover, footprints were more effective than posters, of which the latter did not impact stair use significantly. Results from the survey questionnaire, completed by 46.2 per cent of the employees, showed that, in terms of degree of perception, footprints (91.4 per cent) were more noticeable than posters (46.3 per cent). Originality/value: This paper contributes to the non-conclusive research regarding the effectiveness of nudging interventions on stair use in office environments. It clearly shows that perceptibility in combination with a positive attitude towards the nudge leads to a higher degree of initial behavioural change, yet not to a change of mind.

    Global 3-D Simulations of the Triple Oxygen Isotope Signature Δ17O in Atmospheric CO2
    Koren, Gerbrand ; Schneider, Linda ; Velde, Ivar R. van der; Schaik, Erik van; Gromov, Sergey S. ; Adnew, Getachew A. ; Mrozek Martino, Dorota J. ; Hofmann, Magdalena E.G. ; Liang, Mao Chang ; Mahata, Sasadhar ; Bergamaschi, Peter ; Laan-Luijkx, Ingrid T. van der; Krol, Maarten C. ; Röckmann, Thomas ; Peters, Wouter - \ 2019
    Journal of Geophysical Research: Atmospheres 124 (2019)15. - ISSN 2169-897X - p. 8808 - 8836.
    O excess (ΔO) - carbon cycle - carbon dioxide (CO) - gross primary production (GPP) - mass-independent fractionation (MIF) - stable isotopes

    The triple oxygen isotope signature Δ17O in atmospheric CO2, also known as its “17O excess,” has been proposed as a tracer for gross primary production (the gross uptake of CO2 by vegetation through photosynthesis). We present the first global 3-D model simulations for Δ17O in atmospheric CO2 together with a detailed model description and sensitivity analyses. In our 3-D model framework we include the stratospheric source of Δ17O in CO2 and the surface sinks from vegetation, soils, ocean, biomass burning, and fossil fuel combustion. The effect of oxidation of atmospheric CO on Δ17O in CO2 is also included in our model. We estimate that the global mean Δ17O (defined as Δ17O = ln(δ17O+1)−λRL·ln(δ18O+1) with λRL = 0.5229) of CO2 in the lowest 500 m of the atmosphere is 39.6 per meg, which is ∼20 per meg lower than estimates from existing box models. We compare our model results with a measured stratospheric Δ17O in CO2 profile from Sodankylä (Finland), which shows good agreement. In addition, we compare our model results with tropospheric measurements of Δ17O in CO2 from Göttingen (Germany) and Taipei (Taiwan), which shows some agreement but we also find substantial discrepancies that are subsequently discussed. Finally, we show model results for Zotino (Russia), Mauna Loa (United States), Manaus (Brazil), and South Pole, which we propose as possible locations for future measurements of Δ17O in tropospheric CO2 that can help to further increase our understanding of the global budget of Δ17O in atmospheric CO2.

    Sub-diurnal variability of the carbon dioxide and water vapor isotopologues at the field observational scale
    Vilà-Guerau de Arellano, Jordi ; Koren, Gerbrand ; Ouwersloot, Huug G. ; Velde, Ivar van der; Röckmann, Thomas ; Miller, John B. - \ 2019
    Agricultural and Forest Meteorology 275 (2019). - ISSN 0168-1923 - p. 114 - 135.
    Boundary-layer dynamics - CO - Coupled soil-vegetation-atmosphere model - HO - Harvard Forest observations - Stable isotopologues - Sub-diurnal variability

    We investigated the sub-diurnal variability of the carbon dioxide and water vapour isotopologues by modelling a representative case measured above the Harvard Forest. To this end, we developed a model that couples the local processes governed by soil and vegetation conditions to non-local atmospheric processes such as entrainment and long-range advection. The model formulation is based on solving the stable isotopologues 12CO2, 13CO2, C18OO, H2 16O and H2 18O as conserved variables. It also includes simultaneously solving the meteorological state variables coupled with their respective surface fluxes. Our model results indicate the need for a comprehensive observational data-set to ensure that the essential processes and interactions between the boundary-layer dynamics of a forest and the atmospheric boundary layer are satisfactorily reproduced. We present and discuss the temporal evolution of the budgets of 13CO2 and C18OO, in order to quantify the individual contributions made by soil, plant and entrainment dynamics. All these contributions turn out to be relevant, as they enable us to quantify how the energy, water and carbon fluxes on sub-daily scales are partitioned. Regarding the role played by entrainment, we carried out a set of three systematic experiments in which air, with different CO2 and H2O isotopic compositions originating in the residual layer, mix with the boundary-layer air. Our findings show that both the C18OO and H2 18O isotopic ratios and their respective isofluxes are influenced by the entrainment event. This result indicates that high frequency and accurate isotopologues surface measurements (seconds or minutes)can be used to quantify how non-local atmospheric processes modify isotopic composition at sub-daily scales.

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