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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    Designed Enclosure Enables Guest Binding Within the 4200 A Cavity of a Self-Assembled Cube
    Ramsay, W.J. ; Szczypinski, F.T. ; Weissman, H. ; Ronson, T.K. ; Smulders, M. ; Rybtchinski, B. ; Nitschke, J.R. - \ 2015
    Angewandte Chemie-International Edition 54 (2015)19. - ISSN 1433-7851 - p. 5636 - 5640.
    molecular recognition - supramolecular chemistry - coordination cage - shape-persistent - encapsulation - exchange - host - architectures - complexes - polyhedra
    Metal–organic self-assembly has proven to be of great use in constructing structures of increasing size and intricacy, but the largest assemblies lack the functions associated with the ability to bind guests. Here we demonstrate the self-assembly of two simple organic molecules with CdII and PtII into a giant heterometallic supramolecular cube which is capable of binding a variety of mono- and dianionic guests within an enclosed cavity greater than 4200 Å3. Its structure was established by X-ray crystallography and cryogenic transmission electron microscopy. This cube is the largest discrete abiological assembly that has been observed to bind guests in solution; cavity enclosure and coulombic effects appear to be crucial drivers of host–guest chemistry at this scale. The degree of cavity occupancy, however, appears less important: the largest guest studied, bound the most weakly, occupying only 11¿% of the host cavity.
    Information networks that generate economic value: A study on clusters of adopters of new or improved technologies and practices among oil palm growers in Mexico
    Aguilar-Gallegos, N. ; Muñoz-Rodríguez, M. ; Santoyo-Cortés, H. ; Aguilar-Ávila, J. ; Klerkx, L.W.A. - \ 2015
    Agricultural Systems 135 (2015). - ISSN 0308-521X - p. 122 - 132.
    agricultural innovation systems - sustainable agriculture - conservation practices - knowledge systems - land management - adoption - farmers - exchange - africa - kenya
    The area under cultivation of oil palm has undergone considerable growth in Mexico, but yields are far below their potential. This is related to the low rate of adoption of new or improved technologies and practices in areas such as plantation management and farm administration. This study determines the factors that have an influence on adoption of new or improved technologies and practices and their relationship with the generation of economic value of oil palm. A cluster analysis of 33 key new or improved technologies and practices adopted by 104 growers was performed, and the main adoption categories and the variables influencing adoption are described. The results indicate that three clusters of growers can be discerned that differ in terms of their levels of adoption. The highest level of adoption of new or improved technologies and practices is related to higher yields and vice versa. The new or improved technologies and practices that differentiate the cluster of the advanced adopters from the cluster of the basic adopters are those related to plantation health, grower associations and production unit management. The cluster of the intermediate adopters is outstanding for their levels of adoption of new or improved technologies and practices in the aspects of plant nutrition, harvest, and genetics and reproduction. The advanced adopters set up better links for getting information, generally fromtheir extensionists. The three clusters each exhibit a great degree of homophily, indicating little information flow between the different clusters of growers, while these can learn from each other. These results make it evident that better articulation among different clusters of growers and other actors should be encouraged, and that diversified and tailor-made extension strategies should be designed to optimally support different clusters of growers.
    Assessment of evaporative water loss from Dutch cities
    Jacobs, C.M.J. ; Elbers, J.A. ; Brolsma, R. ; Hartogensis, O.K. ; Moors, E.J. ; Rodríguez-CarreteroMárquez, M.T. ; Hove, B. van - \ 2015
    Building and Environment 83 (2015). - ISSN 0360-1323 - p. 27 - 38.
    klimaatverandering - temperatuur - stedelijke gebieden - evaporatie - waterbudget - rotterdam - veluwe - climatic change - temperature - urban areas - evaporation - water budget - rotterdam - veluwe - urban heat-island - energy-balance - large-aperture - evapotranspiration - exchange - surface - scintillometers - requirements - environments - manchester
    Reliable estimates of evaporative water loss are required to assess the urban water budget in support of division of water resources among various needs, including heat mitigation measures in cities relying on evaporative cooling. We report on urban evaporative water loss from Arnhem and Rotterdam in the Netherlands, using eddy covariance, scintillometer and sapflow observations. Evaporation is assessed at daily to seasonal and annual timescale. For the summer half-year (April–September), observations from Arnhem and Rotterdam are consistent regarding magnitude and variability of evaporation that typically varies between 0.5 and 1.0 mm of evaporation per day. The mean daily evaporative cooling rate was 20–25 Wm-2, 11–14% of the average incoming solar radiation. Evaporation by trees related to sapflow was found to be a small term on the water budget at the city or neighbourhood scale. However, locally the contribution may be significant, given observed maxima of daily sap flows up to 170 l per tree. In Arnhem, evaporation is strongly linked with precipitation, possibly owing to building style. During the summer season, 60% of the precipitation evaporated again. In Rotterdam, the link between evaporation and precipitation is much weaker. An analysis of meteorological observations shows that estimation of urban evaporation from routine weather data using the concept of reference evaporation would be a particularly challenging task. City-scale evaporation may not scale with reference evaporation and the urban fabric results in strong microweather variability. Observations like the ones presented here can be used to evaluate and improve methods for routine urban evaporation estimates.
    Kennis delen onder leraren: Een onderzoek naar de relaties tussen Occupational Self-Efficacy, Werk bevlogenheid, Human Resource Management en Kennis delen
    Vermeulen, M. ; Runhaar, P.R. ; Konermann, J. ; Sanders, K. - \ 2014
    Pedagogische Studiën 91 (2014)6. - ISSN 0165-0645 - p. 397 - 410.
    job resources - performance - behavior - organizations - commitment - metaanalysis - motivation - workplace - community - exchange
    Knowledge sharing is one of the professionalizetion processes and is an important factor in the competition between organizations and for innovation processes to sustain. In this study the central theme is the way knowledge sharing is affected by occupational self-efficacy (OSE), work engagement and High Commitment HRM (HC-HRM). In investigating these relations the AMO framework is used. The research data were obtained by 126 teachers from one secondary school. However from the regression analyses it was learned that the relationship between the variables OSE, HC HRM and work engagement with knowledge sharing was more complex than expected. Additional analyses by means of a three-way interaction analysis suggests that the combination of high experienced HC-HRM and low experienced OSE or the other way around is, related to more knowledge sharing. The findings are important for managers who want to promote processes of knowledge sharing in their school organization.
    Self-organising maps: a versatile tool for the automatic analysis of untargeted metabolomic imaging datasets
    Franceschi, P. ; Wehrens, H.R.M.J. - \ 2014
    Proteomics 14 (2014)7-8. - ISSN 1615-9853 - p. 853 - 861.
    identification - metabolomics - exchange
    MS-based imaging approaches allow for location-specific identification of chemical components in biological samples, opening up possibilities of much more detailed understanding of biological processes and mechanisms. Data analysis, however, is challenging, mainly because of the sheer size of such datasets. This article presents a novel approach based on self-organizing maps, extending previous work in order to be able to handle the large number of variables present in high-resolution mass spectra. The key idea is to generate prototype images, representing spatial distributions of ions, rather than prototypical mass spectra. This allows for a two-stage approach, first generating typical spatial distributions and associated m/z bins, and later analyzing the interesting bins in more detail using accurate masses. The possibilities and advantages of the new approach are illustrated on an in-house dataset of apple slices.
    Predicting consumer behavior with two emotion appraisal dimensions: Emotion valence and agency in gift giving
    Hooge, I.E. de - \ 2014
    International Journal of Research in Marketing 31 (2014)4. - ISSN 0167-8116 - p. 380 - 394.
    cognitive appraisals - positive emotions - consumption emotions - decision-making - cooperation - gratitude - guilt - love - feelings - exchange
    Decades of emotion research have demonstrated the unique influences of many specific emotions on consumer behaviors. These countless numbers of emotion effects can make it difficult to understand the role of emotions in consumer behavior. The current research introduces a parsimonious framework that can predict the effects of emotions on the consumer behavior of gift giving with just two appraisal dimensions: valence and agency. A series of studies examining gift giving reveals that positive emotions exert positive effects on gift giving, independent of their agency. In contrast, agency does predict the effects of negative emotions on gift giving. Negative self-caused emotions increase gift giving, whereas negative other-caused emotions decrease gift giving. These findings seem to hold for inactive and active emotions, and for uncertain and certain emotions. Together, these findings make a unique theoretical and empirical contribution to the understanding of emotions in gift giving. Moreover, it provides a pragmatic framework for both academics and practitioners.
    Agricultural peatlands: towards a greenhouse gas sink - a synthesis of a Dutch landscape study
    Schrier-Uijl, A.P. ; Kroon, P.S. ; Hendriks, D.M.D. ; Hensen, A. ; Huissteden, J. van; Leffelaar, P.A. ; Berendse, F. ; Veenendaal, E.M. - \ 2014
    Biogeosciences 11 (2014). - ISSN 1726-4170 - p. 4559 - 4576.
    anemometer (co)sine response - covariance flux measurements - cut-away peatland - eddy covariance - carbon balance - water-vapor - n2o - exchange - meadow - soil
    It is generally known that managed, drained peatlands act as carbon (C) sources. In this study we examined how mitigation through the reduction of the intensity of land management and through rewetting may affect the greenhouse gas (GHG) emission and the C balance of intensively managed, drained, agricultural peatlands. Carbon and GHG balances were determined for three peatlands in the western part of the Netherlands from 2005 to 2008 by considering spatial and temporal variability of emissions (CO2, CH4 and N2O). One area (Oukoop) is an intensively managed grass-on-peatland area, including a dairy farm, with the ground water level at an average annual depth of 0.55 (±0.37) m below the soil surface. The second area (Stein) is an extensively managed grass-on-peatland area, formerly intensively managed, with a dynamic ground water level at an average annual depth of 0.45 (±0.35) m below the soil surface. The third area is a (since 1998) rewetted former agricultural peatland (Horstermeer), close to Oukoop and Stein, with the average annual ground water level at a depth of 0.2 (±0.20) m below the soil surface. During the measurement campaigns we found that both agriculturally managed sites acted as C and GHG sources and the rewetted former agricultural peatland acted as a C and GHG sink. The ecosystem (fields and ditches) total GHG balance, including CO2, CH4 and N2O, amounted to 3.9 (±0.4), 1.3 (±0.5) and -1.7 (±1.8) g CO2-eq m-2 d-1 for Oukoop, Stein and Horstermeer, respectively. Adding the farm-based emissions to Oukoop and Stein resulted in a total GHG emission of 8.3 (±1.0) and 6.6 (±1.3) g CO2-eq m-2 d-1, respectively. For Horstermeer the GHG balance remained the same since no farm-based emissions exist. Considering the C balance (uncertainty range 40–60%), the total C release in Oukoop and Stein is 5270 and 6258 kg C ha-1 yr-1, respectively (including ecosystem and management fluxes), and the total C uptake in Horstermeer is 3538 kg C ha-1 yr-1. Water bodies contributed significantly to the terrestrial GHG balance because of a high release of CH4. Overall, this study suggests that managed peatlands are large sources of GHGs and C, but, if appropriate measures are taken, they can be turned back into GHG and C sinks within 15 years of abandonment and rewetting. The shift from an intensively managed grass-on-peat area (Oukoop) to an extensively managed one (Stein) reduced the GHG emissions mainly because N2O emission and farm-based CH4 emissions decreased.
    N2O consumption by low-nitrogen soil and its regulation by water and oxygen
    Wu, D.M. ; Dong, W.X. ; Oenema, O. ; Wang, Y.Y. ; Trebs, I. ; Hu, C.S. - \ 2013
    Soil Biology and Biochemistry 60 (2013). - ISSN 0038-0717 - p. 165 - 172.
    spruce forest soil - aerobic denitrification - oxide - fluxes - emissions - exchange - n-2 - no - bacteria - nitrate
    Soils can be a source and sink for atmospheric nitrous oxide (N2O). Consumption of N2O has been reported for anoxic soils and sediments rich in organic matter and depleted in nitrates (NO3-), and also for some dry, oxic soils. However, the mechanisms and controls of N2O consumption in dry soil are not clear. Here, we report on a field study in China (Taihang mountain region, Shijiazhuang), in which N2O uptake by a sandy loam soil was measured for the greater part of the season (from April to October in 2011), and on four incubation experiments, in which we tried to reveal the roles of water content and oxygen (O-2) concentrations on N2O consumption. Flux measurements in the field were made bi-weekly on unfertilized cropped land with static flux chambers (5 replicates) for 6 months. The results show that N2O-N fluxes ranged from -26.0 to -726.6 mu g m(-2) h(-1). Consumption of N2O was largest when the soil was dry (5-20% soil water filled pore space). In the incubation experiments, N2O consumption and N-2 production were measured in (an)aerobic soil with soil moisture content ranging from 1% to 50% (wt/wt) and with N2O addition, using a thermostatic, robotized incubation system. Under anaerobic conditions, N2O was rapidly consumed at water content of >10% (wt/wt). However, a significant consumption also occurred at 1% soil moisture. Under aerobic conditions, N2O consumption increased with increasing soil moisture content, but significant consumption was still measured at 2% moisture. Sterilization of oxic soil completely blocked N2O consumption, suggesting that the consumption had a biological nature. In conclusion, the steady N2O consumption measured in the field was confirmed by the laboratory experiments, but the relationship with soil moisture content was reversed. Further studies are required to understand this apparent anomaly.
    Towards the integration of research and monitoring at forest ecosystems in Europe
    Danielewska, A. ; Paoletti, E. ; Clarke, N. ; Olejnik, J. ; Urbaniak, M. ; Baran, M. ; Siedlecki, P. ; Hansen, K. ; Lundin, L. ; Vries, W. de - \ 2013
    Forest Systems 22 (2013)3. - ISSN 2171-5068 - p. 535 - 545.
    eddy covariance measurements - carbon balance - climate-change - air-pollution - mixed forest - heat fluxes - water-vapor - co2 - exchange - boreal
    Aim of study: The main aim of the work was to summarize availability, quality and comparability of on-going European Research and Monitoring Networks (ERMN), based on the results of a COST FP0903 Action questionnaire carried out in September 2010 and May 2012. Area of study: The COST Action FP0903 involves 29 European countries and 4 non-COST institutions from USA, Morocco and Tunisia. In this study, the total of 22 replies to the questionnaire from 18 countries were included. Materials and methods: Based on the feedback from the Action FP0903 countries, the most popular European Networks were identified. Thereafter, the access to the network database, available quality assurance/quality control procedures and publication were described. Finally, the so-called “Supersites” concept, defined as a “highly instrumented research infrastructure, for both research and monitoring of soil-plant-atmosphere interactions” was discussed. Main results: The result of the survey indicate that the vast majority of the Action FP0903 countries participate in the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forest (ICP Forest). The multi-disciplinary International Cooperative Programme on Integrated Monitoring of Air Pollution Effects on Ecosystems (ICPIM) is the second most widespread forest programme. Research highlights: To fully understand biochemical cycles in forest ecosystems, long-term monitoring is needed. Hence, a network of “Supersites”, is proposed. The application of the above infrastructure can be an effective way to attain a better integration of research and monitoring networks at forest sites in Europe
    The importance of crop growth modeling to interpret the ¿14CO2 signature of annual plants
    Bozhinova, D.N. ; Combe, M. ; Palstra, S.W.L. ; Meijer, H.A.J. ; Krol, M.C. ; Peters, W. - \ 2013
    Global Biogeochemical Cycles 27 (2013)3. - ISSN 0886-6236 - p. 792 - 803.
    fossil-fuel co2 - atmospheric carbon-dioxide - c-14 - (co2)-c-14 - radiocarbon - netherlands - exchange - records - yield
    [1] The 14C/C abundance in CO2(¿14CO2) promises to provide useful constraints on regional fossil fuel emissions and atmospheric transport through the large gradients introduced by anthropogenic activity. The currently sparse atmospheric ¿14CO2 monitoring network can potentially be augmented by using plant biomass as an integrated sample of the atmospheric ¿14CO2. But the interpretation of such an integrated sample requires knowledge about the day¿to¿day CO2 uptake of the sampled plants. We investigate here the required detail in daily plant growth variations needed to accurately interpret regional fossil fuel emissions from annual plant samples. We use a crop growth model driven by daily meteorology to reproduce daily fixation of ¿14CO2 in maize and wheat plants in the Netherlands in 2008. When comparing the integrated ¿14CO2 simulated with this detailed model to the values obtained when using simpler proxies for daily plant growth (such as radiation and temperature), we find differences that can exceed the reported measurement precision of ¿14CO2(~2‰). Furthermore, we show that even in the absence of any spatial differences in fossil fuel emissions, differences in regional weather can induce plant growth variations that result in spatial gradients of up to 3.5‰ in plant samples. These gradients are even larger when interpreting separate plant organs (leaves, stems, roots, or fruits), as they each develop during different time periods. Not accounting for these growth¿induced differences in ¿14CO2 in plant samples would introduce a substantial bias (1.5–2¿ppm) when estimating the fraction of atmospheric CO2 variations resulting from nearby fossil fuel emissions
    Quantifying the uncertainties of advection and boundary layer dynamics on the diurnal carbon dioxide budget
    Pino, D. ; Kaikkonen, J.P. ; Vilà-Guerau de Arellano, J. - \ 2013
    Journal of Geophysical Research: Atmospheres 118 (2013)16. - ISSN 2169-897X - p. 9376 - 9392.
    co2 mixing ratios - atmospheric co2 - regional-scale - error characterization - transport models - cabauw tower - tall tower - exchange - flux - entrainment
    [1] We investigate the uncertainties in the carbon dioxide (CO2) mixing ratio and inferred surface flux associated with boundary layer processes and advection by using mixed-layer theory. By extending the previous analysis presented by Pino et al. (2012), new analytical expressions are derived to quantify the uncertainty of CO2 mixing ratio or surface flux associated to, among others, boundary layer depth, early morning CO2 mixing ratio at the mixed layer or at the free atmosphere; or CO2 advection. We identify and calculate two sorts of uncertainties associated to the CO2 mixing ratio and surface flux: instantaneous and past (due to advection). The numerical experiments are guided and constrained by meteorological and CO2 observations taken at the Cabauw 213 m tower. We select 2 days (25 September 2003 and 12 March 2004) with a well-defined convective boundary layer but different CO2 advection contributions. Our sensitivity analysis shows that uncertainty of the CO2 advection in the boundary layer due to instantaneous uncertainties represents at 1600 LT on 12 March 2004 a contribution of 2¿ppm and 0.072 mg m-2s-1 in the uncertainty of the CO2 mixing ratio and inferred surface flux, respectively. Taking into account that the monthly averaged minimum CO2 surface flux for March 2004 was -0.55 mg m-2s-1, the error on the surface flux is on the order of 10%. By including CO2 advection in the analytical expressions, we demonstrate that the uncertainty of the CO2 mixing ratio or surface flux also depends on the past uncertainties of the boundary layer depth.
    Evapotranspiration amplifies European summer drought
    Teuling, A.J. ; Loon, A.F. van; Seneviratne, S.I. ; Lehner, I. ; Aubinet, M. ; Heinesch, B. ; Bernhofer, C. ; Grünwald, T. ; Prasse, H. ; Spank, U. - \ 2013
    Geophysical Research Letters 40 (2013)10. - ISSN 0094-8276 - p. 2071 - 2075.
    forest - simulations - exchange - carbon - scale
    Drought is typically associated with a lack of precipitation, whereas the contribution of evapotranspiration and runoff to drought evolution is not well understood. Here we use unique long-term observations made in four headwater catchments in central and western Europe to reconstruct storage anomalies and study the drivers of storage anomaly evolution during drought. We provide observational evidence for the “drought-paradox” in that region: a consistent and significant increase in evapotranspiration during drought episodes, which acts to amplify the storage anomalies. In contrast, decreases in runoff act to limit storage anomalies. Our findings stress the need for the correct representation of evapotranspiration and runoff processes in drought indices.
    Exploring the Impact of Land Cover and Topography on Rainfall Maxima in the Netherlands
    Maat, H.W. ter; Moors, E.J. ; Hutjes, R.W.A. ; Holtslag, A.A.M. ; Dolman, A.J. - \ 2013
    Journal of Hydrometeorology 14 (2013)2. - ISSN 1525-755X - p. 524 - 542.
    landgebruik - bossen - neerslag - bodemwater - simulatie - modellen - veluwe - land use - forests - precipitation - soil water - simulation - models - veluwe - climate-change - convective boundary - soil-moisture - surface - model - evaporation - prediction - diffusion - exchange
    The relative contribution of topography and land use on precipitation is analyzed in this paper for a forested area in the Netherlands. This area has an average yearly precipitation sum that can be 75–100 mm higher than the rest of the country. To analyze this contribution, different configurations of land use and topography are fed into a mesoscale model. The authors use the Regional Atmospheric Modeling System (RAMS) coupled with a land surface scheme simulating water vapor, heat, and momentum fluxes [Soil–Water–Atmosphere Plant System–Carbon (SWAPS-C)]. The model simulations are executed for two periods that cover varying large-scale synoptic conditions of summer and winter periods. The output of the experiments leads to the conclusion that the precipitation maximum at the Veluwe is forced by topography and land use. The effect of the forested area on the processes that influence precipitation is smaller in summertime conditions when the precipitation has a convective character. In frontal conditions, the forest has a more pronounced effect on local precipitation through the convergence of moisture. The effect of topography on monthly domain-averaged precipitation around the Veluwe is a 17% increase in the winter and a 10% increase in the summer, which is quite remarkable for topography with a maximum elevation of just above 100 m and moderate steepness. From this study, it appears that the version of RAMS using Mellor–Yamada turbulence parameterization simulates precipitation better in wintertime, but the configuration with the medium-range forecast (MRF) turbulence parameterization improves the simulation of precipitation in convective circumstances.
    Harming others’ task-related efforts: The distinct competitive effects of ranking information on performance and mastery goal individuals
    Poortvliet, P.M. - \ 2013
    Social Psychology 44 (2013)6. - ISSN 1864-9335 - p. 373 - 379.
    achievement goals - conflict regulation - orientations - exchange - context - pleasure - behavior - outcomes - impact - pain
    This paper demonstrates that, when individuals with mastery goals and their exchange partners occupy increasingly higher ranks on a task (#4 and #5 vs. #51 and #52 or #96 and #97, on a top-100), they display stronger interpersonally harmful behavior in order to interfere with exchange partners’ task performance. In contrast, performance goal individuals damage the task performance of others more when ranks are low or high rather than average (#4 and #5 or #96 and #97 vs. #51 and #52). These results signify that social comparison information is processed differently by mastery and performance goal individuals. The resulting interpersonally harmful behaviors depend on whether such behavior is instrumental for their particular achievement goal pursuit or not
    Simultaneous assimilation of satellite and eddy covariance data for improving terrestrial water and carbon simulations at a semi-arid woodland site in Botswana
    Kato, T. ; Knorr, W. ; Scholtze, M. ; Veenendaal, E.M. ; Kaminski, T. ; Kattge, J. ; Gobron, N. - \ 2013
    Biogeosciences 10 (2013). - ISSN 1726-4170 - p. 789 - 802.
    land-surface model - isba-a-gs - atmospheric co2 - soil-moisture - exchange - photosynthesis - transpiration - uncertainties - variability - biosphere
    Terrestrial productivity in semi-arid woodlands is strongly susceptible to changes in precipitation, and semi-arid woodlands constitute an important element of the global water and carbon cycles. Here, we use the Carbon Cycle Data Assimilation System (CCDAS) to investigate the key parameters controlling ecological and hydrological activities for a semi-arid savanna woodland site in Maun, Botswana. Twenty-four eco-hydrological process parameters of a terrestrial ecosystem model are optimized against two data streams separately and simultaneously: daily averaged latent heat flux (LHF) derived from eddy covariance measurements, and decadal fraction of absorbed photosynthetically active radiation (FAPAR) derived from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS). Assimilation of both data streams LHF and FAPAR for the years 2000 and 2001 leads to improved agreement between measured and simulated quantities not only for LHF and FAPAR, but also for photosynthetic CO2 uptake. The mean uncertainty reduction (relative to the prior) over all parameters is 14.9% for the simultaneous assimilation of LHF and FAPAR, 8.5% for assimilating LHF only, and 6.1% for assimilating FAPAR only. The set of parameters with the highest uncertainty reduction is similar between assimilating only FAPAR or only LHF. The highest uncertainty reduction for all three cases is found for a parameter quantifying maximum plant-available soil moisture. This indicates that not only LHF but also satellite-derived FAPAR data can be used to constrain and indirectly observe hydrological quantities.
    Microfluidic preparation and self diffusion PFG-NMR analysis of monodisperse water-in-oil-in-water double emulsions
    Hughes, E. ; Maan, A.A. ; Acquistapace, S. ; Burbidge, J.A. ; Johns, M.L. ; Gunes, D.Z. ; Clausen, P. ; Syrbe, A. ; Hugo, J. ; Schroën, C.G.P.H. - \ 2013
    Journal of Colloid and Interface Science 389 (2013)1. - ISSN 0021-9797 - p. 147 - 156.
    nuclear-magnetic-resonance - restricted diffusion - multiple emulsions - w/o/w emulsions - systems - field - echo - exchange - sizes - tool
    Monodisperse water-in-oil-in-water (WOW) double emulsions have been prepared using microfluidic glass devices designed and built primarily from off the shelf components. The systems were easy to assemble and use. They were capable of producing double emulsions with an outer droplet size from 100 to 40 µm. Depending on how the devices were operated, double emulsions containing either single or multiple water droplets could be produced. Pulsed-field gradient self-diffusion NMR experiments have been performed on the monodisperse water-in-oil-in-water double emulsions to obtain information on the inner water droplet diameter and the distribution of the water in the different phases of the double emulsion. This has been achieved by applying regularization methods to the self-diffusion data. Using these methods the stability of the double emulsions to osmotic pressure imbalance has been followed by observing the change in the size of the inner water droplets over time.
    Sensitivity and uncertainty of analytical footprint models according to a combined natural tracer and ensemble approach
    Boer, A. van de; Moene, A.F. ; Schüttemeyer, D. ; Graf, A. - \ 2013
    Agricultural and Forest Meteorology 169 (2013). - ISSN 0168-1923 - p. 1 - 11.
    flux measurements - sonic anemometer - carbon-dioxide - surface-layer - water-vapor - exchange - heat - validation - efflux - fetch
    Evaluations of analytical footprint models using data from several stations located in different land use types are still scarce, but valuable for defining the spatial context of the measurements. Therefore, we evaluated two analytical footprint models by applying a ‘forward’ and an ‘inversion’ method. We used eddy covariance measurements from a flat agricultural landscape in western Germany in the summer of 2009, with seven eddy covariance systems over three different land use types with contrasting sensible heat fluxes. We found that the model of Hsieh et al. (2000. Adv. Water Resour. 23, 765–772) and of Kormann and Meixner (2001. Boundary Layer Meteorol. 99, 207–224) are both overestimating the distance of the peak contribution of the footprint. In our evaluation, the former model performs slightly better, independent of whether the crosswind dispersion was used from the latter model, or from the proposed model by Detto et al. (2006. Water Resour. Res. 42, 1–16).
    Attributing the impacts of land-cover changes in temperate regions on surface temperature and heat fluxes to specific causes: Results from the first LUCID set of simulations
    Boisier, J.P. ; Noblet-Ducoudré, N. de; Pitman, A.J. ; Cruz, F.T. ; Delire, C. ; Hurk, B.J.J.M. van den; Molen, M.K. van der; Müller, C. ; Voldoire, A. - \ 2012
    Journal of Geophysical Research: Atmospheres 117 (2012)D12. - ISSN 2169-897X
    climate system model - soil-moisture - sensitivity - feedbacks - forcings - exchange - forest - energy - biomes - albedo
    Surface cooling in temperate regions is a common biogeophysical response to historical Land-Use induced Land Cover Change (LULCC). The climate models involved in LUCID show, however, significant differences in the magnitude and the seasonal partitioning of the temperature change. The LULCC-induced cooling is directed by decreases in absorbed solar radiation, but its amplitude is 30 to 50% smaller than the one that would be expected from the sole radiative changes. This results from direct impacts on the total turbulent energy flux (related to changes in land-cover properties other than albedo, such as evapotranspiration efficiency or surface roughness) that decreases at all seasons, and thereby induces a relative warming in all models. The magnitude of those processes varies significantly from model to model, resulting on different climate responses to LULCC. To address this uncertainty, we analyzed the LULCC impacts on surface albedo, latent heat and total turbulent energy flux, using a multivariate statistical analysis to mimic the models' responses. The differences are explained by two major ‘features’ varying from one model to another: the land-cover distribution and the simulated sensitivity to LULCC. The latter explains more than half of the inter-model spread and resides in how the land-surface functioning is parameterized, in particular regarding the evapotranspiration partitioning within the different land-cover types, as well as the role of leaf area index in the flux calculations. This uncertainty has to be narrowed through a more rigorous evaluation of our land-surface models.
    Network strength, transaction-specific investments, inter-personal trust, and relationship satisfaction in Chinese agrifood SMEs
    Lu Hualiang, ; Feng, S. ; Trienekens, J.H. ; Omta, S.W.F. - \ 2012
    China Agricultural Economic Review 4 (2012)3. - ISSN 1756-137X - p. 363 - 378.
    buyer-seller relationships - supplier relationships - social-structure - moderating role - channel - guanxi - cost - performance - governance - exchange
    Purpose - The purpose of this paper is to investigate the effects of network strength, transaction-specific investments and inter-personal trust on business relationship satisfaction for small-and-medium-sized enterprises (SMEs) involved in agri-food processing and exporting in China. Design/methodology/approach - Survey data collected from 80 agri-food SMEs in Jiangsu Province were used for empirical testing: The authors applied an ordered logit regression approach for model estimation. Findings - The results demonstrate that strong guanxi networks, high level of transaction-specific investments and inter-personal trust significantly contribute to a high level of relationship satisfaction for agri-food SMEs in China. In addition, inter-personal trust shows a. moderating effect on the relationship between transaction-specific investments and relationship satisfaction. Practical implications - Business relationships play a critical role in the modern market environment. Relational arrangements (based on guanxi and inter-personal trust) should be further enhanced in order to yield satisfied business relationships for SMEs in China. Originality/value - The paper extends our understanding of relationship (guanxi) marketing, as well as marketing practices for agri-food SMEs in China.
    Inverse carbon dioxide flux estimates for the Netherlands
    Meesters, A.G.C.A. ; Tolk, L.F. ; Peters, W. ; Hutjes, R.W.A. ; Vellinga, O.S. ; Elbers, J.A. ; Vermeulen, A.T. ; Laan, S. van der; Neubert, R. ; Meijer, H.A.J. ; Dolman, A.J. - \ 2012
    Journal of Geophysical Research: Atmospheres 117 (2012). - ISSN 2169-897X - 13 p.
    transport models - atmospheric co2 - regional-scale - tower - emissions - exchange
    CO2 fluxes for the Netherlands and surroundings are estimated for the year 2008, from concentration measurements at four towers, using an inverse model. The results are compared to direct CO2 flux measurements by aircraft, for 6 flight tracks over the Netherlands, flown multiple times in each season. We applied the Regional Atmospheric Mesoscale Modeling system (RAMS) coupled to a simple carbon flux scheme (including fossil fuel), which was run at 10 km resolution, and inverted with an Ensemble Kalman Filter. The domain had 6 eco-regions, and inversions were performed for the four seasons separately. Inversion methods with pixel-dependent and -independent parameters for each eco-region were compared. The two inversion methods, in general, yield comparable flux averages for each eco-region and season, whereas the difference from the prior flux may be large. Posterior fluxes co-sampled along the aircraft flight tracks are usually much closer to the observations than the priors, with a comparable performance for both inversion methods, and with best performance for summer and autumn. The inversions showed more negative CO2 fluxes than the priors, though the latter are obtained from a biosphere model optimized using the Fluxnet database, containing observations from more than 200 locations worldwide. The two different crop ecotypes showed very different CO2 uptakes, which was unknown from the priors. The annual-average uptake is practically zero for the grassland class and for one of the cropland classes, whereas the other cropland class had a large net uptake, possibly because of the abundance of maize there.
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