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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    Deriving animal behaviour from high-frequency GPS: tracking cows in open and forested habitat
    Weerd, N. de; Langevelde, F. van; Oeveren, H. van; Nolet, B.A. ; Kölzsch, A. ; Prins, H.H.T. ; Boer, W.F. de - \ 2015
    PLoS ONE 10 (2015)6. - ISSN 1932-6203 - 17 p.
    collar performance - large herbivores - telemetry data - movement - cattle - ecology - states - technology - selection - position
    The increasing spatiotemporal accuracy of Global Navigation Satellite Systems (GNSS) tracking systems opens the possibility to infer animal behaviour from tracking data.We studied the relationship between high-frequency GNSS data and behaviour, aimed at developing an easily interpretable classification method to infer behaviour from location data. Behavioural observations were carried out during tracking of cows (Bos Taurus) fitted with high-frequency GPS (Global Positioning System) receivers. Data were obtained in an open field and forested area, and movement metrics were calculated for 1 min, 12 s and 2 s intervals. We observed four behaviour types (Foraging, Lying, Standing and Walking). We subsequently used Classification and Regression Trees to classify the simultaneously obtained GPS data as these behaviour types, based on distances and turning angles between fixes. GPS data with a 1 min interval from the open field was classified correctly for more than 70% of the samples. Data from the 12 s and 2 s interval could not be classified successfully, emphasizing that the interval should be long enough for the behaviour to be defined by its characteristic movement metrics. Data obtained in the forested area were classified with a lower accuracy (57%) than the data from the open field, due to a larger positional error of GPS locations and differences in behavioural performance influenced by the habitat type. This demonstrates the importance of understanding the relationship between behaviour and movement metrics, derived from GNSS fixes at different frequencies and in different habitats, in order to successfully infer behaviour. When spatially accurate location data can be obtained, behaviour can be inferred from high-frequency GNSS fixes by calculating simple movement metrics and using easily interpretable decision trees. This allows for the combined study of animal behaviour and habitat use based on location data, and might make it possible to detect deviations in behaviour at the individual level.
    Modelling biomechanical requirements of a rider for different horse-riding techniques at trot
    Cocq, P. de; Muller, M. ; Clayton, H.M. ; Leeuwen, J.L. van - \ 2013
    Journal of Experimental Biology 216 (2013). - ISSN 0022-0949 - p. 1850 - 1861.
    energy-cost - carrying loads - walking - mechanics - speed - energetics - carriage - position - springs - back
    The simplest model possible for bouncing systems consists of a point mass bouncing passively on a mass-less spring without viscous losses. This type of spring–mass model has been used to describe the stance period of symmetric running gaits. In this study, we investigated the interaction between horse and rider at trot using three models of force-driven spring (–damper)–mass systems. The first system consisted of a spring and a mass representing the horse that interact with another spring and mass representing the rider. In the second spring–damper–mass model, dampers, a free-fall and a forcing function for the rider were incorporated. In the third spring–damper–mass model, an active spring system for the leg of the rider was introduced with a variable spring stiffness and resting length in addition to a saddle spring with fixed material properties. The output of the models was compared with experimental data of sitting and rising trot and with the modern riding technique used by jockeys in racing. The models show which combinations of rider mass, spring stiffness and damping coefficient will result in a particular riding technique or other behaviours. Minimization of the peak force of the rider and the work of the horse resulted in an ‘extreme’ modern jockey technique. The incorporation of an active spring system for the leg of the rider was needed to simulate rising trot. Thus, the models provide insight into the biomechanical requirements a rider has to comply with to respond effectively to the movements of a horse.
    Time of collection and cutting sizes affect vegetative propagation of Boswellia papyrifera (Del.) Hochst through leafless branch cuttings
    Haile, G. ; Gebrehiwot, K. ; Lemenih, M. ; Bongers, F. - \ 2011
    Journal of Arid Environments 75 (2011)9. - ISSN 0140-1963 - p. 873 - 877.
    frankincense - position
    Boswellia papyrifera (Del) Hochst is a key dry land plant species in the Horn of Africa with high socio-economic significance in Ethiopia, Eritrea and Sudan. In recent decades, populations of this species are declining due to lack of recruitment through natural regeneration. This study investigated the potential of vegetative propagation using leafless branch cuttings as an alternative means of reproduction for the species. The effect of time of collection and cutting sizes (length and thickness) on shooting and rooting of the cuttings was investigated. The effects of these three factors were analysed, two-by-two, in three separate factorial experiments each arranged in a randomized complete block design. Time of collection affected cutting performance: shooting percent, shoot number, cutting vigour, leaf number, leaf length, rooting percent and root length were best when cuttings were collected in February–March, and weakest in May. Medium to long cuttings (1.0 m–2.0 m) and thicker cuttings (0.19–0.27 m) performed better than shorter or thinner cuttings. These results indicate that B. papyrifera is amenable to macro-propagation via leafless branch cuttings. Reproduction of B. papyrifera through macro-propagation may help overcome the population recruitment bottleneck of this important species and will help the long-term yield possibilities of its precious product frankincense
    Verbetering van de lichtonderschepping in een tomatengewas door aanpassing van de rijstructuur: Effecten van de rijstructuur op lichtverdeling, fotosynthese en productie
    Dueck, T.A. ; Nederhoff, E.M. ; Nieboer, S. ; Scheffers, C.P. ; Steenhuizen, J.W. ; Chizhmak, S. ; Uenk, D. ; Sarlikioti, V. ; Visser, P.H.B. de - \ 2010
    Wageningen : Wageningen UR Greenhouse Horticulture (Rapport GTB 1029) - 46
    solanum lycopersicum - tomaten - kasgewassen - teelt onder bescherming - cultuurmethoden - licht - interceptie - ruimtelijke verdeling - adaptatie - positie - effecten - fotosynthese - solanum lycopersicum - tomatoes - greenhouse crops - protected cultivation - cultural methods - light - interception - spatial distribution - adaptation - position - effects - photosynthesis
    Doel van dit project was te onderzoeken wat het effect is van de rijstructuur op de lichtverdeling en fotosynthese van een tomatengewas, en de effecten daarvan op de productie. Ook werd gekeken of de bladstand en de fotosynthesecapaciteit van de bladeren zich aanpassen aan wijzigende lichtverdeling. Tevens werd de hypothese getest of alternatieve vormen van tussenplanten zouden leiden tot lagere verdamping en dus tot energiebesparing. Verder is gekeken naar het effect op productie van twee substraten, namelijk kokosmatten type ‘Profit’ van Van der Knaap, en steenwolmat type ‘Master Dry’ van Grodan.
    Genetic differences in fruit-set patterns are determined by differences in fruit sink strength and a source : sink threshold for fruit set
    Wubs, A.M. ; Ma, Y.T. ; Heuvelink, E. ; Marcelis, L.F.M. - \ 2009
    Annals of Botany 104 (2009)5. - ISSN 0305-7364 - p. 957 - 964.
    pepper capsicum-annuum - flower abscission - cultivars - cucumber - growth - competition - position - tomato - susceptibility - temperature
    Background and Aims: Fruit set in indeterminate plant species largely depends on the balance between source and sink strength. Plants of these species show fluctuations in fruit set during the growing season. It was tested whether differences in fruit sink strength among the cultivars explained the differences in fruit-set patterns. Methods: Capsicum was chosen as a model plant. Six cultivars with differences in fruit set, fruit size and plant growth were evaluated in a greenhouse experiment. Fruit-set patterns, generative and vegetative sink strength, source strength and the source : sink ratio at fruit set were determined. Sink strength was quantified as potential growth rate. Fruit set was related to total fruit sink strength and the source : sink ratio. The effect of differences observed in above-mentioned parameters on fruit-set patterns was examined using a simple simulation model. Key Results: Sink strengths of individual fruits differed greatly among cultivars. Week-to-week fruit set in large-fruited cultivars fluctuated due to large fluctuations in total fruit sink strength, but in small-fruited cultivars, total fruit sink strength and fruit set were relatively constant. Large variations in week-to-week fruit set were correlated with a low fruit-set percentage. The source : sink threshold for fruit set was higher in large-fruited cultivars. Simulations showed that within the range of parameter values found in the experiment, fruit sink strength and source : sink threshold for fruit set had the largest impact on fruit set: an increase in these parameters decreased the average percentage fruit set and increased variation in weekly fruit set. Both were needed to explain the fruit-set patterns observed. The differences observed in the other parameters (e.g. source strength) had a lower effect on fruit set. Conclusions: Both individual fruit sink strength and the source : sink threshold for fruit set were needed to explain the differences observed between fruit-set patterns of the six cultivars
    Voor landschap bestaat geen markt
    Os, L.J. van - \ 2009
    Kennis Online 2009 (2009)feb. - p. 8 - 8.
    landinrichting - landschapsbescherming - rijksoverheid - positie - land development - landscape conservation - central government - position
    Een mooi land kost 64 miljoen, 600 miljoen, of nog veel meer, zo berekende het Planbureau voor de Leefomgeving (PBL). Dat hangt af van je wensen. Het planbureau is daarnaast bezorgd over de zwakke positie van landschap in het politieke debat. De rijksoverheid zal zelf over de brug moeten komen als het op korte termijn landschapsdoelen wil realiseren
    Genetic analysis of results of a Swedish behavior test on German Shepherd Dogs and Labrador Retrievers1
    Waaij, E.H. van der; Wilsson, E. ; Strandberg, E. - \ 2008
    Journal of Animal Science 86 (2008). - ISSN 0021-8812 - p. 2853 - 2861.
    performance traits - sexual-behavior - breed - selection - season - domestication - heritability - adolescents - parameters - position
    The objectives of this study were to estimate genetic parameters and the influence of systematic effects on behavior test results in dogs. Behavior test results on 1,813 Labrador Retrievers (LR) and 2,757 German Shepherd Dogs (GSD) were analyzed. The behavior test included observations on courage, defense drive, prey drive, nerve stability, temperament, cooperation, affability, and gun shyness. Sex and age influenced most of the traits, and seasons of birth and testing and litter size and composition influenced some of the traits. Apart from defense drive in GSD, and courage, nerve stability, hardness, and affability in LR, all traits were heritable, with heritabilities ranging from 0.14 for hardness to 0.38 for affability in GSD, and from 0.03 for affability to 0.56 for gun shyness in LR. Genetic correlations ranged from 1.00 (LR) and 0.95 (GSD) between courage and hardness to ¿0.01 (LR) and ¿0.03 (GSD) between gun shyness and defense drive. Most genetic correlations were positive. Correlations with cooperation were mainly negative, especially in GSD. Genetic correlations between courage and defense drive in LR (0.26) and GSD (0.80), between courage and prey drive in LR (0.27) and GSD (0.65), between affability and nerve stability in LR (0.09) and GSD (0.64), between affability and temperament in LR (¿0.24) and GSD (0.39), and between cooperation and hardness in LR (0.28) and GSD (¿0.67) were significantly different between the breeds. Genetic parameters for defense drive and cooperation in GSD and hardness and gun shyness in LR were genetically different between the sexes. Results of this study indicate that correction for systematic effects is essential when making selection decisions. Estimating breeding values would be a good solution, incorporating both correction for systematic effects and using all genetic links. Genetic parameters need to be estimated for each breed separately.
    The opinion of Dutch dietitians about functional foods
    Jong, N. ; Hoendervangers, C.T. ; Bleeker, J.K. ; Ocke, M.C. - \ 2004
    Journal of Human Nutrition and Dietetics 17 (2004)1. - ISSN 0952-3871 - p. 55 - 62.
    american-dietetic-association - health - position
    Objective To obtain information about Dutch dietitian's attitudes, perceived knowledge, training preferences, counselling procedures, opinions about post-launch monitoring, and personal consumption of functional foods. Design A self-administered, 62-item, postal survey in 2002. Subjects Five hundred randomly selected registered dietitians. The response rate was 49% (n = 238). Results The responders (mean age ± SD: 40 ± 9 years) had regular contact with clients (90%), and many (71% of 90%) advised about functional food use. Sixty-nine per cent hardly consumed any functional food themselves. Eighty-seven per cent of the responders would greatly appreciate courses given by scientists. Confusion existed about usage practices, target groups, safety, efficacy, and claims: between 42 and 89% agreed with the statements about uncertainties. Nonetheless, 69% felt that functional foods could theoretically contribute to good bodily functioning. Ninety per cent thought post-launch monitoring (PLM) important, but ideas about a common dietetic contribution to PLM did not emerge. Conclusions Although functional foods potentially contribute to a healthful diet, there is still confusion among dietitians about claims, safety, efficacy and product-handling aspects. It is time to meet dietitians' repeated requests to provide education by noncommercial experts. In the meantime, dietitians themselves should have more say in the PLM debate because they should and could play an important role.
    Effect of a tripeptide on the aggregational behaviour of the blue mussel Mytilus edulis
    Vooys, C.G.N. de - \ 2003
    Marine Biology (2003)6. - ISSN 0025-3162 - p. 1119 - 1123.
    marine organisms - signal molecules - peptide analogs - settlement - waterborne - position - environments - pheromone - dynamics - release
    Aggregation of blue mussels (Mytilus edulis) is stimulated by environmental chemical stimuli. Experiments carried out in a basin with a one-way current showed that individual mussels were attracted to upstream mussel concentrations and moved actively in their direction. The involvement of a tripeptide in this migration was implicated by experiments demonstrating that individual mussels were effectively attracted and moved actively towards a source of glycine-glycine-arginine at concentrations of 0.56-3.78 x 10-10 M. A distinct seasonal difference in the extent of movement towards mussel concentrations was found. From the beginning of autumn, movement decreases linearly towards zero movement in winter.
    Gebruik van Global Positioning System (GPS) binnen Telen met toekomst. Plaatsbepaling bij monstername op de Voorloperbedrijven
    Smit, A.L. - \ 2002
    Wageningen : Plant Research International (Telen met toekomst / Praktijkonderzoek Plant en Omgeving, Plant Research International, DLV Adviesgroep nv OV 0201) - 10
    bemonsteren - positie - globale plaatsbepalingssystemen - sampling - position - global positioning systems
    Meten en beoordelen variatie in grasopbrengst binnen graslandpercelen
    Lokhorst, C. ; Radersma, H. ; Kasper, G. ; Werkhoven, C. - \ 1997
    Agro Informatica 10 (1997)5. - ISSN 0925-4455 - p. 5 - 7.
    droge stof - graslanden - geografische informatiesystemen - positie - lokalisatie - optische instrumenten - meting - geneeskunde - schatting - gewassen - oogstvoorspelling - geodesie - dry matter - grasslands - geographical information systems - position - localization - optical instruments - measurement - medicine - estimation - crops - yield forecasting - geodesy
    De auteurs laten zien dat het mogelijk is opbrengstkaarten van grasland te produceren en geven inzicht in de informatieaspecten die daarbij een rol spelen
    Geografische informatie voor plaats specifieke werkzaamheden.
    Goense, D. ; Hofstee, J.W. ; Bergeijk, J. van - \ 1995
    Agro Informatica 8 (1995)3. - ISSN 0925-4455 - p. 28 - 32.
    geografische informatiesystemen - lokalisatie - positie - precisielandbouw - geodesie - geographical information systems - localization - position - precision agriculture - geodesy
    Presentatie van een gestructureerd informatiemodel als basis voor gegevensverwerking met betrekking tot plaatsspecifieke veldwerkzaamheden, waarbij ook het gebruik van coordinaatsystemen aan de orde komt
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