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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Antwoorden op de quiz mestscore
Vijgeboom, W. ; Huisman, T.R. - \ 2011
dierentuindieren - dierenwelzijn - diervoeding - diergezondheid - dierlijke meststoffen - zoo animals - animal welfare - animal nutrition - animal health - animal manures
Poster met antwoorden op de quiz mestscore: de diersoort en mestscore zijn nu bij de verschillende soorten mest geplaatst.
Planten giftig voor (dierentuin) dieren
Hillen, R. ; Huisman, T.R. - \ 2011
dierentuindieren - dierenwelzijn - diervoeding - giftige planten - vergiftiging - diergezondheid - zoo animals - animal welfare - animal nutrition - poisonous plants - poisoning - animal health
Poster met een overzicht van planten die giftig zijn voor (dierentuin)dieren.
Body Condition Score
Vijgeboom, W. ; Huisman, T.R. - \ 2011
dierentuindieren - dierenwelzijn - diervoeding - diergezondheid - zoo animals - animal welfare - animal nutrition - animal health
Poster on the Body Condition Score (BCS) as a tool to visually assess whether the animal is overweight or too thin.
Quiz Body Condition Score
Vijgeboom, W. ; Huisman, T.R. - \ 2011
dierentuindieren - dierenwelzijn - diervoeding - diergezondheid - zoo animals - animal welfare - animal nutrition - animal health
Poster with a quiz on Body Condition Scores. Different Body Condition Scores are described. The goal is to give each animal the correct score.
Answers quiz Body Condition Score
Vijgeboom, W. ; Huisman, T.R. - \ 2011
dierentuindieren - dierenwelzijn - diervoeding - diergezondheid - zoo animals - animal welfare - animal nutrition - animal health
Poster with answers to the quiz Body Condition Score (BCS). The correct scores are given to each animal.
Fecal scoring system
Vijgeboom, W. ; Huisman, T.R. - \ 2011
dierentuindieren - dierenwelzijn - diervoeding - feces - excreten - diergezondheid - zoo animals - animal welfare - animal nutrition - faeces - excreta - animal health
Poster on the assessment of feces of different animals. Colour, shape and solidity of excrement say something about an animal, the kind of food it gets and the quality of the food.
Quiz fecal scoring system
Vijgeboom, W. ; Huisman, T.R. - \ 2011
dierentuindieren - dierenwelzijn - diervoeding - feces - excreten - diergezondheid - zoo animals - animal welfare - animal nutrition - faeces - excreta - animal health
Poster with a quiz on fecal scoring. Which animal species and which fecal score belong to the feces shown?
Answers quiz fecal scoring system
Vijgeboom, W. ; Huisman, T.R. - \ 2011
dierentuindieren - dierenwelzijn - diervoeding - feces - excreten - diergezondheid - zoo animals - animal welfare - animal nutrition - faeces - excreta - animal health
Poster with answers to the quiz on fecal scoring. The correct animal species and fecal score are given for the feces shown.
Plants poisonous to zoo animals
Huisman, T.R. - \ 2011
dierentuindieren - dierenwelzijn - diervoeding - giftige planten - diergezondheid - zoo animals - animal welfare - animal nutrition - poisonous plants - animal health
Poster giving an overview of plants that are poisonous to zoo animals.
"Roofdiervoeding" meer spiegelen aan de natuur?
Huisman, T.R. - \ 2011
zoo animals - animal nutrition - animal welfare - carnivores - animal behaviour - animal health - teaching materials
Dierentuinvoeding: knelpunten en aanpak
Huisman, T.R. - \ 2011
zoo animals - animal welfare - animal nutrition - food composition - animal behaviour - animal health - teaching materials
BCS als hulpmiddel : docentendag dierentuinvoedingscursus 8 februari 2011
Huisman, T.R. - \ 2011
zoo animals - animal nutrition - animal welfare - animal health - body condition - monitoring - teaching materials
Varying disease-mediated selection at different life-history stages of Atlantic salmon in fresh water
Eyto, E. de; McGinnity, P. ; Huisman, J. ; Coughlan, J. ; Consuegra, S. ; Megens, H.J.W.C. - \ 2011
Evolutionary Applications 4 (2011)6. - ISSN 1752-4563 - p. 749 - 762.
major histocompatibility complex - class-i locus - salar l. - genetic-variation - pathogen resistance - balancing selection - natural-selection - wild populations - local adaptation - climate-change
Laboratory studies on associations between disease resistance and susceptibility and major histocompatibility (MH) genes in Atlantic salmon Salmo salar have shown the importance of immunogenetics in understanding the capacity of populations to fight specific diseases. However, the occurrence and virulence of pathogens may vary spatially and temporally in the wild, making it more complicated to predict the overall effect that MH genes exert on fitness of natural populations and over several life-history stages. Here we show that MH variability is a significant determinant of salmon survival in fresh water, by comparing observed and expected genotype frequencies at MH and control microsatellite loci at parr and migrant stages in the wild. We found that additive allelic effects at immunogenetic loci were more likely to determine survival than dominance deviation, and that selection on certain MH alleles varied with life stage, possibly owing to varying pathogen prevalence and/or virulence over time. Our results highlight the importance of preserving genetic diversity (particularly at MH loci) in wild populations, so that they have the best chance of adapting to new and increased disease challenges as a result of projected climate warming and increasing aquaculture
Biotechnology based processes for arsenic removal
Huisman, J. ; Olde Weghuis, M. ; Gonzalez-Contreras, P.A. - \ 2011
The regulations for arsenic control have become strict. Therefore, better technologies to remove arsenic from bleeds and effluents are desired. In addition, no single solution is suitable for all cases. The properties of the process streams and the storage facilities are major factors determining the selection of a certain technology. In this paper, two technologies are described. What these technologies have in common is that they are based on high-rate engineered bioreactors that allow optimal control, efficient resource use, and predictable and reliable process performance. One technology (Arsenoteq) converts arsenic to corodite, which is most suitable for storage under oxidising conditions. The other technology (Thioteq) operates under reducing conditions and produces arsenic sulphide (As2S3, orpiment) with 61 mass% arsenic. The first technology is suitable for medium to high (> 1000 mg/L) concentrations of arsenic in acidic process streams, whereas the latter is ideal for effluent treatment up to <5000 mg/L of arsenic. The residual arsenic concentration that can be obtained with the latter method is <0.1 mg/L.
Bioscorodite crystallization for arsenic removal
Gonzalez-Contreras, P.A. ; Huisman, J. ; Weijma, J. ; Buisman, C.J.N. - \ 2011
In: Proceedings of 6th European Metallurgical Conference, June 26-29, 2011, Düsseldorf, Germany. - - p. 1751 - 1762.
In the bio-scorodite process, arsenic is precipitated as crystalline iron arsenate, i.e. scorodite (FeAsO4·2H2O). This is a more economic and more environmentally friendly method for arsenic immobilization than the chemical production of iron- or calcium arsenate, as fewer chemicals are needed. Moreover, scorodite is an attractive medium for arsenic control and immobilization because it is stable, compact and has a very low solubility. Therefore it is regarded as the most ideal form for long-term arsenic storage. We have demonstrated that bio-crystallization of arsenic into scorodite crystals is possible with the aid of microorganisms. The operational conditions of the bio-scorodite process allow for a fast growth of the microorganisms and facilitate the crystallization of scorodite, avoiding the precipitation of other iron oxides or amorphous iron arsenates. The bio-scorodite process brings several advantages compared to chemical crystallization such as the lower required temperature (70°C), the control of supersaturation by biological oxidation and no need for crystal parents or seeds to begin the crystallization. Arsenic concentrations are removed to ppm level with starting concentrations ranging from 1000 to 2000 mg L-1. The produced bioscorodite crystals are very similar to the scorodite mineral found in nature. By control of the iron feed and the pH, the production of other iron precipitates is avoided. The latter facilitates easy separation of the solid product. Based on their highly crystalline nature, the biogenic scorodite crystals seem very suitable for safe disposal. At present the research has started with the continuous production of scorodite in bioreactors. The follow-up challenges are focused on the selection of a suitable reactor configuration.
Resonance of plankton communities with temperature fluctuations
Beninca, E. ; Dakos, V. ; Nes, E.H. van; Huisman, J. ; Scheffer, M. - \ 2011
American Naturalist 178 (2011)4. - ISSN 0003-0147 - p. E85 - E95.
colored environmental noise - predator-prey system - food-web - population-dynamics - sustained oscillations - extinction risk - chaos - time - phytoplankton - variability
The interplay between intrinsic population dynamics and environmental variation is still poorly understood. It is known, however, that even mild environmental noise may induce large fluctuations in population abundances. This is due to a resonance effect that occurs in communities on the edge of stability. Here, we use a simple predator-prey model to explore the sensitivity of plankton communities to stochastic environmental fluctuations. Our results show that the magnitude of resonance depends on the timescale of intrinsic population dynamics relative to the characteristic timescale of the environmental fluctuations. Predator-prey communities with an intrinsic tendency to oscillate at a period T are particularly responsive to red noise characterized by a timescale of [Formula: see text]. We compare these theoretical predictions with the timescales of temperature fluctuations measured in lakes and oceans. This reveals that plankton communities will be highly sensitive to natural temperature fluctuations. More specifically, we demonstrate that the relatively fast temperature fluctuations in shallow lakes fall largely within the range to which rotifers and cladocerans are most sensitive, while marine copepods and krill will tend to resonate more strongly with the slower temperature variability of the open ocean
Modeling of desorption of Alfalfa (Medicago sativa) stems and leaves.
ArabHosseini, A. ; Huisman, W. ; Müller, J. - \ 2011
Industrial Crops and Products 34 (2011)3. - ISSN 0926-6690 - p. 1550 - 1555.
moisture sorption isotherms - temperature - equations - dryer
The equilibrium moisture content of agricultural products is necessary to optimize drying process and helps to keep the quality of the product during the period of storage. The main aim of this research was to find the best model which could define well, the exchange of moisture between alfalfa (Medicago sativa) and the surrounding air. The desorption isotherms of alfalfa (stem and leaf) were determined separately by using the saturated salt solutions method at three temperatures (25, 50 and 70 °C) within a range of 5–90% relative humidity. Experimental curves of desorption isotherms were fitted to modified equations of Henderson, Halsey, Oswin and Chung-Pfost as well as the GAB model and then evaluated visually by using residual plots and also by some statistical error parameters. The modified Halsey model was found to be the most suitable for describing the relationship between equilibrium moisture content, relative humidity and temperature.
Meerjarige tuinbouwsamenwerking met Indonesië beëindigd: HORTIN, terugblik op een succesvolle samenwerking
Everaarts, A.P. ; Huisman, W. - \ 2011
Berichten buitenland 37 (2011)1/2. - ISSN 0920-0975 - p. 6 - 7.
tuinbouw - samenwerking - ontwikkelingsprogramma's - indonesië - horticulture - cooperation - development programmes - indonesia
Eind november 2010 werd in Jakarta de tweede fase van het programma Horticultural Research co-operation between Indonesia and The Netherlands (HORTIN) afgesloten. De eerste fase liep van 2003 tot en met 2006. De samenwerking in de eerste fase concentreerde zich op onderzoek. Tijdens de tweede fase (2007-2010) lag de nadruk op co-innovatie en ontwikkeling in de hele keten, van productie tot afzet van tuinbouwproducten, in nauwe samenwerking met bedrijven uit het mkb.
Effect of Drying on the Color of Tarragon (Artemisia dracunculus L.) Leaves
ArabHosseini, A. ; Padhye, S. ; Huisman, W. ; Boxtel, A.J.B. van; Müller, J. - \ 2011
Food Bioprocess Technology 4 (2011)7. - ISSN 1935-5130 - p. 1281 - 1287.
thermal kinetics - puree - degradation - quality
The effect of drying conditions on the color of tarragon (Artemisia dracunculus L.) leaves was studied. Tarragon leaves were dried at temperatures of 40 to 90 °C with a constant airflow of 0.6 m/s. The samples were collected at 7%, 10%, 20%, and 30% moisture content wet basis for evaluation of the color change. The color parameters of fresh and dried leaves were measured by a colorimeter. The individual parameters of L*a*b* and L*C*h° color systems were evaluated and h° proved to be the best parameter to monitor color change. The smallest change of the color parameters was observed at 40 °C, in which temperature was low, and also at 90 °C, when drying time was short. The biggest change occurred at the temperatures of 50 to 70 °C. Most of the color change happened before the material reaches 35% moisture content. The combination of drying time and temperature defines the change of color.
Modeling of the equilibrium moisture content (EMC) of Miscanthus (Miscanthus x giganteus)
ArabHosseini, A. ; Huisman, W. ; Muller, J. - \ 2010
Biomass and Bioenergy 34 (2010)4. - ISSN 0961-9534 - p. 411 - 416.
sorption isotherms - equations - crop
The desorption isotherms of miscanthus, Miscanthus x giganteus (stems and leaves) were determined separately by using the saturated salt solutions method at three temperatures (25, 50 and 70 degrees C) within a range from 5 to 90% relative humidity. Experimental curves of desorption isotherms were fitted to Modified Henderson, Modified Halsey, Modified Oswin and Modified Chung-Pfost models and evaluated by Residual Sum of Squares (RSS), Standard Error Estimation (SEE) and Mean Relative Deviation (MAD) methods. The Modified Oswin model was found to be the most suitable for describing the correlation between equilibrium moisture content, relative humidity and temperature.
Diverging affinity of tospovirus RNA silencing suppressor proteins, NSs, for various RNA duplex molecules
Schnettler, E. ; Hemmes, J.C. ; Huisman, R. ; Goldbach, R.W. ; Prins, M.W. ; Kormelink, R.J.M. - \ 2010
Journal of Virology 84 (2010)21. - ISSN 0022-538X - p. 11542 - 11554.
spotted-wilt-virus - double-stranded-rna - antiviral immunity - interfering rna - drosophila-melanogaster - viral suppressors - in-vivo - gene - plant - cells
The tospovirus NSs protein was previously shown to suppress the antiviral RNA silencing mechanism in plants. Here the biochemical analysis of NSs proteins from different tospoviruses, using purified NSs or NSs containing cell extracts, is described. The results showed that all tospoviral NSs proteins analyzed exhibited affinity to small double-stranded RNA molecules, i.e., small interfering RNAs (siRNAs) and micro-RNA (miRNA)/miRNA* duplexes. Interestingly, the NSs proteins from tomato spotted wilt virus (TSWV), impatiens necrotic spot virus (INSV), and groundnut ringspot virus (GRSV) also showed affinity to long double-stranded RNA (dsRNA), whereas tomato yellow ring virus (TYRV) NSs did not. The TSWV NSs protein was shown to be capable of inhibiting Dicer-mediated cleavage of long dsRNA in vitro. In addition, it suppressed the accumulation of green fluorescent protein (GFP)-specific siRNAs during coinfiltration with an inverted-repeat-GFP RNA construct in Nicotiana benthamiana. In vivo interference of TSWV NSs in the miRNA pathway was shown by suppression of an enhanced GFP (eGFP) miRNA sensor construct. The ability to stabilize miRNA/miRNA* by different tospovirus NSs proteins in vivo was demonstrated by increased accumulation and detection of both miRNA171c and miRNA171c* in tospovirus-infected N. benthamiana. All together, these data suggest that tospoviruses interfere in the RNA silencing pathway by sequestering siRNA and miRNA/miRNA* molecules before they are uploaded into their respective RNA-induced silencing complexes. The observed affinity to long dsRNA for only a subset of the tospoviruses studied is discussed in light of evolutional divergence and their ancestral relation to the animal-infecting members of the Bunyaviridae
Landelijk onderzoek naar teken en de ziekte van Lyme
Takken, W. ; Vliet, A.J.H. van; Huisman, M. - \ 2010
Wageningen : Wageningen Universiteit (Nieuwsbrief # 33 (november – december) )
Landelijk onderzoek naar teken en de ziekte van Lyme
Takken, W. ; Vliet, A.J.H. van; Huisman, M. - \ 2010
Wageningen : Wageningen Universiteit (Nieuwsbrief # 32 (september – oktober) )
Landelijk onderzoek naar teken en de ziekte van Lyme
Takken, W. ; Vliet, A.J.H. van; Huisman, M. - \ 2010
Wageningen : Wageningen Universiteit (Nieuwsbrief # 31 (juli – augustus) )
Landelijk onderzoek naar teken en de ziekte van Lyme
Takken, W. ; Vliet, A.J.H. van; Huisman, M. - \ 2010
Wageningen : Wageningen Universiteit (Nieuwsbrief # 30 (mei – juni) )
Landelijk onderzoek naar teken en de ziekte van Lyme
Takken, W. ; Vliet, A.J.H. van; Huisman, M. - \ 2010
Wageningen : Wageningen Universiteit (Nieuwsbrief # 29 (maart – april) )
Landelijk onderzoek naar teken en de ziekte van Lyme
Takken, W. ; Vliet, A.J.H. van; Huisman, M. - \ 2010
Wageningen : Wageningen Universiteit (Nieuwsbrief # 28 (januari – februari) )
Onderwijsproject "Animal Welfare Quality Management"
Huisman, T.J. ; Reijd, P. van der; Hopster, H. ; Miedema, S. ; Ooijen, M. ; Pompe, V.M.M. ; Verheijen, C. ; Ophorst, S. ; Brandt, H. van den; Knobbe, L. ; Bos, J. ; Koenis, I. - \ 2010
dierenwelzijn - agrarisch onderwijs - onderwijsprogramma's - kwaliteitszorg - animal welfare - agricultural education - education programmes - quality management
Poster met informatie over het onderwijsproject "Animal Welfare Quality Management": introductie, beoogde resultaten, aanpak en resultaten per mei 2008.
"Met kennis beter doen" ook uitgangspunt bij dierentuinvoeding
Huisman, T.J. ; Polet, J.J. ; Spit, L. ; Kuperus, S. - \ 2010
dierentuindieren - dierenwelzijn - diervoeding - dierentuinen - lesmaterialen - zoo animals - animal welfare - animal nutrition - zoological gardens - teaching materials
Voeding is bepalend voor gezondheid en welzijn van dieren. Theoretische kennis over voeding in alle geledingen van de dierentuinorganisatie draagt bij aan de communicatie hierover. Dit leidt tot meer uitwisseling tussen praktijk en theorie en betere acceptatie van voedingsvoorschriften.
Dierentuinvoeding
Huisman, T. - \ 2010
onderwijsmethoden - dierentuindieren - diervoeding - dierenwelzijn - lesmaterialen - teaching methods - zoo animals - animal nutrition - animal welfare - teaching materials
Factsheet met informatie over het KIGO project over dierentuinvoeding.
Is there chaos out there? : analysis of complex dynamics in plankton communities
Benincà, E. - \ 2010
Wageningen University. Promotor(en): Marten Scheffer; J. Huisman, co-promotor(en): K. Jöhnk; Egbert van Nes. - [S.l. : S.n. - ISBN 9789085858126 - 169
plankton - waterorganismen - veranderingen in de bevolking - populatiedichtheid - populatiedynamica - chaos - wiskundige modellen - populatiebiologie - aquatic organisms - population change - population density - population dynamics - mathematical models - population biology
Species often show irregular fluctuations in their population abundances. Traditionally, ecologists have thought that external processes (e.g., variability in weather conditions) are the main drivers of these ups and downs. However, recent theoretical work suggests that fluctuations in natural populations may also be driven by internal mechanisms (e.g., the interplay between species). In this thesis I use a combination of time series analysis and modeling to provide more insight into the question to which extent such internally generated chaos might drive the population dynamics of plankton communities under controlled as well as natural conditions. In short, this thesis demonstrates in theory and experiment that species in plankton communities may rise and fall forever in a chaotic way. This result challenges the traditional view that nature is at equilibrium and that only externally driven processes may disturb this equilibrium.
Effects of exercise on l-carnitine and lipid metabolism in African catfish (Clarias gariepinus) fed different dietary l-carnitine and lipid levels
Ozorio, R.O.A. ; Ginneken, V.J.T. van; Bessa, R.J.B. ; Verstegen, M.W.A. ; Verreth, J.A.J. ; Huisman, E.A. - \ 2010
The British journal of nutrition 103 (2010)8. - ISSN 0007-1145 - p. 1139 - 1150.
trout oncorhynchus-mykiss - bream pagrus-major - high-fat diets - salmo-salar l - rainbow-trout - growth-performance - exhaustive exercise - nutritional supplements - intermediary metabolism - swimming performance
African catfish (Clarias gariepinus) were fed four isonitrogenous diets (34 % crude protein), each containing one of two lipid (100 or 180 g/kg) and two l-carnitine (15 or 1000 mg/kg) levels. After 81 d of feeding, thirty-two fish (body weight 32 g) from each dietary group were randomly selected, sixteen fish were induced to a 3-h swim (speed of 1.5 body length (BL)/s), while the other sixteen fish were kept under resting condition. Fish fed 1000 mg l-carnitine accumulated 3.5 and 5 times more l-carnitine in plasma and muscle, respectively, than fish fed the 15 mg l-carnitine. Muscle l-carnitine content was significantly lower in exercised fish than in rested fish. High dietary lipid level (fish oil) led to an increase in muscle n-3 PUFA content and a decrease in SFA and MUFA content. In liver, the increase in dietary lipid level resulted in an increased levels of both n-6 and n-3 PUFA. l-carnitine supplementation significantly decreased n-3 PUFA content. Exercise decreased n-3 PUFA in both muscle and liver. Plasma lactate and lactate dehydrogenase, normally associated with increased glycolytic processes, were positively correlated with exercise and inversely correlated with dietary l-carnitine level. l-carnitine supplementation reduced significantly the RQ from 0.72 to 0.63, and an interaction between dietary l-carnitine and lipid was observed (P <0.03). Our results indicate that an increase in fatty acids (FA) intake may promote FA oxidation, and both carnitine and exercise might influence the regulation of FA oxidation selectivity.
Coupled predator-prey oscillations in a chaotic food web
Benincà, E. ; Johnk, K.D. ; Heerkloss, R. ; Huisman, J. - \ 2009
Ecology Letters 12 (2009)12. - ISSN 1461-023X - p. 1367 - 1378.
wavelet analysis - time-series - ecological dynamics - populations - abundance - models - cycles - synchronization - biodiversity - competition
Coupling of several predator-prey oscillations can generate intriguing patterns of synchronization and chaos. Theory predicts that prey species will fluctuate in phase if predator-prey cycles are coupled through generalist predators, whereas they will fluctuate in anti-phase if predator-prey cycles are coupled through competition between prey species. Here, we investigate predator-prey oscillations in a long-term experiment with a marine plankton community. Wavelet analysis of the species fluctuations reveals two predator-prey cycles that fluctuate largely in anti-phase. The phase angles point at strong competition between the phytoplankton species, but relatively little prey overlap among the zooplankton species. This food web architecture is consistent with the size structure of the plankton community, and generates highly dynamic food webs. Continued alternations in species dominance enable coexistence of the prey species through a non-equilibrium 'killing-the-winner' mechanism, as the system shifts back and forth between the two predator-prey cycles in a chaotic fashion.
Investigating Neolithic land use in Swifterbant (NL) using micromorphological techniques
Huisman, D.J. ; Jongmans, A.G. ; Raemaekers, D.C.M. - \ 2009
Catena 78 (2009)3. - ISSN 0341-8162 - p. 185 - 197.
In the Swifterbant area in The Netherlands, a complete Neolithic landscape is preserved, buried in a wetland environment. A dozen sites (dating from ca. 4300-4000 cal. BC) on levees of a former creek system are characterized by a black layer containing large amounts of carbonized plant remains, burnt bone, flint and pottery. These sites are usually interpreted as occupation sites with accumulated refuse of a society in transition from a Mesolithic to a Neolithic lifestyle (hunting and herding), in an area that was too wet for crops. In the context of a new research campaign in the area, we investigated the site- and land-use on two locations (S2 and S4) using micromorphological techniques. On S2, the soil matrix in the archaeological horizon has a heterogeneous, non-sedimentary appearance due to the ubiquitous presence of rounded and subrounded aggregates. These aggregates indicate that the sediment was disturbed after deposition, but it is unclear by what human activity. This disturbance is not restricted to the archaeological site horizon, but extends also into the under- and overlying layers. On S4, three layers can be distinguished. Only the lower and central parts are usually regarded as archaeological layers. The lower layer shows thorough mixing of the (partly decalcified) groundmass and the incorporation of anthropogenic materials (carbonized plant remains, burnt bone, etc.). Most probably, the thorough mixing is a result of tillage. The central layer consists of thinly laminated phytoliths and carbonized plant remains with ample fragments of (burnt) bone, angular sediment clods and some dog coprolites. Mineral sediments are absent. Apparently, the layer was formed by human activities that resulted in a massive accumulation of burnt organic materials and anthropogenic debris. The preservation of the microlayering formed by phytoliths and carbonized is remarkable, since trampling would have deformed or disturbed the layering. The surprising conclusion therefore has to be that this location was not the main settlement area-as was implicitly thought until now. Rather, the area should be interpreted as a location where specific activities resulted in the accumulation of burnt plant material, e.g. a waste dump. The upper layer again has indications of anthropogenic soil disturbance. Samples from the basin adjacent to the levee site show sediments that are deformed by trampling. The transition of the site to the channel shows no signs of trampling, but rather interfingering of site layers with channel sediments. Lack of trampling in the central zone of S4 and the adjacent channel shore is at odds with the classical interpretation that the site represents a settlement area. The black layers that up till now were thought to encompass a complete settlement, could very well be a very prominent part of larger sites with remains of human activities during the Neolithic
Energieproducerende Kas levert vooral kennis op (interview met Feije de Zwart)
Jagers op Akkerhuis, F. ; Zwart, H.F. de - \ 2009
Vakblad voor de Bloemisterij 64 (2009)5. - ISSN 0042-2223 - p. 44 - 45.
tuinbouwbedrijven - kassen - energie - onderzoek - glastuinbouw - semi-gesloten kassen - market gardens - greenhouses - energy - research - greenhouse horticulture - semi-closed greenhouses
Het onderzoek naar de Energieproducerende Kas bij Hydro Huisman is afgerond. Het blijkt mogelijk om met een kas energie te verzamelen en te gebruiken voor klimaatregeling. Momenteel is het systeem echter nog niet rendabel, al heeft het onderzoek ook praktisch bruikbare inzichten opgeleverd
Interannual variability in species composition explained as seasonally entrained chaos
Dakos, V. ; Beninca, E. ; Nes, E.H. van; Philippart, C.J.M. ; Scheffer, M. ; Huisman, J. - \ 2009
Proceedings of the Royal Society. B: Biological Sciences 276 (2009)1669. - ISSN 0962-8452 - p. 2871 - 2880.
predator-prey system - competitive-exclusion - phytoplankton biomass - marine-phytoplankton - plankton dynamics - food webs - models - stability - patterns - daphnia
The species composition of plankton, insect and annual plant communities may vary markedly from year to year. Such interannual variability is usually thought to be driven by year-to-year variation in weather conditions. Here we examine an alternative explanation. We studied the effects of regular seasonal forcing on a multi-species predator–prey model consisting of phytoplankton and zooplankton species. The model predicts that interannual variability in species composition can easily arise without interannual variability in external conditions. Seasonal forcing increased the probability of chaos in our model communities, but squeezed these irregular species dynamics within the seasonal cycle. As a result, the population dynamics had a peculiar character. Consistent with long-term time series of natural plankton communities, seasonal variation led to a distinct seasonal succession of species, yet the species composition varied from year to year in an irregular fashion. Our results suggest that interannual variability in species composition is an intrinsic property of multi-species communities in seasonal environments
The ecological stoichiometry of toxins produced by harmful cyanobacteria: an experimental test of the carbonnutrient balance hypothesis
Waal, D.B. van de; Verspagen, J.M.H. ; Lürling, M.F.L.L.W. ; Donk, E. van; Visser, P.M. ; Huisman, J. - \ 2009
Ecology Letters 12 (2009)2. - ISSN 1461-023X - p. 1326 - 1335.
limited microcystis-aeruginosa - planktothrix-agardhii - inorganic carbon - growth-rate - light - nitrogen - phytoplankton - population - metabolism - blooms
The elemental composition of primary producers reflects the availability of light, carbon and nutrients in their environment. According to the carbon-nutrient balance hypothesis, this has implications for the production of secondary metabolites. To test this hypothesis, we investigated a family of toxins, known as microcystins, produced by harmful cyanobacteria. The strain Microcystis aeruginosa HUB 5-2-4, which produces several microcystin variants of different N:C stoichiometry, was cultured in chemostats supplied with various combinations of nitrate and CO2. Excess supply of both nitrogen and carbon yielded high cellular N:C ratios accompanied by high cellular contents of total microcystin and the nitrogen-rich variant microcystin-RR. Comparable patterns were found in Microcystis-dominated lakes, where the relative microcystin-RR content increased with the seston N:C ratio. In total, our results are largely consistent with the carbon-nutrient balance hypothesis, and warn that a combination of rising CO2 and nitrogen enrichment will affect the microcystin composition of harmful cyanobacteria
Local positive feedback and the persistence and recovery of fringe Avicennia marina (Forssk.) Vierh. mangroves
Huisman, T.J. ; Langevelde, F. van; Boer, W.F. de - \ 2009
Wetlands Ecology and Management 17 (2009)6. - ISSN 0923-4861 - p. 601 - 611.
early-life history - early growth - ecosystems - restoration - australia - establishment - regeneration - propagules - patterns - forests
While mangrove restoration efforts are reasonably successful, failure often occurs in high wave energy situations. Due to differences in wave energy, seedling mortality rates vary strongly with position on the intertidal flat between high water spring and high water neap elevations. However, a local positive feedback can be present between the pneumatophores of adult mangroves and the survival of mangrove seedlings to trigger recovery. In this study, a mangrove population of Avicennia marina is modelled to determine the effects of seedling mortality and local positive feedback on mangrove recovery. The model uses life history data and dispersal to simulate population dynamics. The mangrove range limits are determined by high water spring and high water neap levels. The results indicate that within these limits mangrove populations with life-history parameter values as derived from literature are indeed capable of fast growth under conditions with low seedling mortality. Local positive feedback has then a small positive influence on population recovery after mangrove loss. If, however, mortality rates increase, such as in high wave energy situations, the importance of a positive feedback increases. The model shows that a positive feedback may, given high seedling mortality rates, be an important factor for mangrove recovery. While a positive feedback may enable mangrove persistence in unfavourable conditions, destruction of adult mangroves can remove the positive feedback, which would render the system uninhabitable and practically prohibits reforestation of such areas. The model results and the presence of positive feedbacks and their importance for population dynamics in harsh conditions indicate that investigating and understanding possible feedbacks could be crucial for successful restoration efforts
Omgaan met digitale nationale beleidskaarten
Vullings, L.A.E. ; Blok, C. ; Vonk, G.A. ; Heusden, M. van; Huisman, A. ; Linge, J.M. van; Keijzer, S. ; Oldengarm, J. ; Bulens, J.D. - \ 2009
Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-werkdocument 141) - 44
kaarten - interpretatie - overheidsbeleid - nederland - geografische informatiesystemen - visualisatie - maps - interpretation - government policy - netherlands - geographical information systems - visualization
In dit werkdocument worden de resultaten besproken van een casestudy die onderdeel is van het project GeO3 - Omgaan met onzekerheid binnen Ruimtelijke Ordening. De directie Platteland van het ministerie van LNV heeft bij het publiceren van het meerjarenprogramma van Agenda Vitaal Platteland geen digitale viewer gepubliceerd omdat men bang was voor verkeerde interpretatie van de digitale kaarten. In dit project is gekeken naar methoden en cartografische oplossingen om voortaan zonder angst voor misinterpretaties digitale nationale beleidskaarten te kunnen verspreiden. De oplossing is gezocht in het opstellen van een handreiking, zodat kaarten ook daadwerkelijk weergeven wat er bedoeld is door de maker.
Citric acid wastewater as electron donor for biological sulfate reduction
Stams, A.J.M. ; Huisman, J. ; Garcia Encina, P.A. ; Muyzer, G. - \ 2009
Applied Microbiology and Biotechnology 83 (2009)5. - ISSN 0175-7598 - p. 957 - 963.
sp-nov. - lactosphaera-pasteurii - ruminococcus-palustris - citrate metabolism - reducing bacteria - comb-nov - gen-nov - reactor - veillonella - reclassification
Citrate-containing wastewater is used as electron donor for sulfate reduction in a biological treatment plant for the removal of sulfate. The pathway of citrate conversion coupled to sulfate reduction and the microorganisms involved were investigated. Citrate was not a direct electron donor for the sulfate-reducing bacteria. Instead, citrate was fermented to mainly acetate and formate. These fermentation products served as electron donors for the sulfate-reducing bacteria. Sulfate reduction activities of the reactor biomass with acetate and formate were sufficiently high to explain the sulfate reduction rates that are required for the process. Two citrate-fermenting bacteria were isolated. Strain R210 was closest related to Trichococcus pasteurii (99.5% ribosomal RNA (rRNA) gene sequence similarity). The closest relative of strain S101 was Veillonella montepellierensis with an rRNA gene sequence similarity of 96.7%. Both strains had a complementary substrate range
De energieproducerende kas bij Hydro Huisman
Zwart, Feije de - \ 2009
greenhouses - protected cultivation - energy conservation - cogeneration - greenhouse horticulture - energy saving
Modeling of thin layer drying of tarragon (Artemisia dracunculus L.)
ArabHosseini, A. ; Huisman, W. ; Boxtel, A.J.B. van; Mueller, J. - \ 2009
Industrial Crops and Products 29 (2009)1. - ISSN 0926-6690 - p. 53 - 59.
sweet-potato slices - bay leaves - hot air - parameters
The drying behavior of tarragon leaves as well as chopped plants were evaluated at air temperatures ranging from 40 to 90 °C, at various air relative humidities and a constant air velocity of 0.6 m/s. The experimental data was fitted to a number of thin layer drying equations. The equations were classified to select the more relevant one. Three equations were selected and the coefficients of the equations were compared by three statistical parameters as residual sum of squares, standard error of estimate and mean relative deviation. The effect of temperature on the coefficients of the three selected equations was evaluated by nonlinear regression. The results show that higher temperature cause shorter drying time. Separated leaves have shorter drying time compared to chopped plants. Although the Diffusion approach equation showed the best fit, the Page equation was selected, since it had almost a similar performance but the equation is simpler with two parameters instead of three. Then a function was derived describing the relationship between the two parameter values and drying temperature.
The timescale of phenotypic plasticity and its impact on competition in fluctuating environments
Stomp, M. ; Dijk, M.A. van; Overzee, H.M.J. van; Wortel, M.T. ; Sigon, C.A.M. ; Egas, M. ; Hoogveld, H. ; Gons, H.J. ; Huisman, J. - \ 2008
American Naturalist 172 (2008)5. - ISSN 0003-0147 - p. E169 - E185.
complementary chromatic adaptation - fresh-water picocyanobacteria - phototrophic microorganisms - marine synechococcus - variable environment - selective advantage - inducible defenses - experimental tests - baltic sea - light
Although phenotypic plasticity can be advantageous in fluctuating environments, it may come too late if the environment changes fast. Complementary chromatic adaptation is a colorful form of phenotypic plasticity, where cyanobacteria tune their pigmentation to the prevailing light spectrum. Here, we study the timescale of chromatic adaptation and its impact on competition among phytoplankton species exposed to fluctuating light colors. We parameterized a resource competition model using monoculture experiments with green and red picocyanobacteria and the cyanobacterium Pseudanabaena, which can change its color within approximately 7 days by chromatic adaptation. The model predictions were tested in competition experiments, where the incident light color switched between red and green at different frequencies (slow, intermediate, and fast). Pseudanabaena (the flexible phenotype) competitively excluded the green and red picocyanobacteria in all competition experiments. Strikingly, the rate of competitive exclusion was much faster when the flexible phenotype had sufficient time to fully adjust its pigmentation. Thus, the flexible phenotype benefited from its phenotypic plasticity if fluctuations in light color were relatively slow, corresponding to slow mixing processes or infrequent storms in their natural habitat. This shows that the timescale of phenotypic plasticity plays a key role during species interactions in fluctuating environments.
Evaluation of vaccination strategies against infection with feline immunodeficiency virus (FIV) based on recombinant viral vectors expressing FIV Rev and OrfA
Huisman, W. ; Schrauwen, E.J.A. ; Tijhaar, E. ; Süzer, Y. ; Pas, S.D. ; Amerongen, G. van; Sutter, G. ; Rimmelzwaan, G.F. ; Osterhaus, A.D.M.E. - \ 2008
Veterinary Immunology and Immunopathology 126 (2008)3-4. - ISSN 0165-2427 - p. 332 - 338.
cytotoxic t-lymphocytes - semliki-forest-virus - envelope glycoprotein - protective immunity - subunit vaccines - rhesus macaques - 89.6p challenge - animal-model - tat protein - replication
In recent years it has become clear that cell-mediated immunity is playing a role in the control of lentivirus infections. In particular, cytotoxic T lymphocyte responses have been associated with improved outcome of infection, especially those directed against the regulatory proteins like Rev and Tat, which are expressed early after infection. Therefore, there is considerable interest in lentiviral vaccine candidates that can induce these types of immune responses. In the present study, we describe the construction and characterisation of expression vectors based on recombinant Semliki Forest virus system and modified vaccinia virus Ankara for the expression of feline immunodeficiency virus (FIV) accessory proteins Rev and OrfA. These recombinant viral vectors were used to immunize cats using a prime-boost regimen and the protective efficacy of this vaccination strategy was assessed after challenge infection of immunized cats with FIV.
Chaos in a long-term experiment with a plankton community
Beninca, E. ; Huisman, J. ; Heerkloss, R. ; Jöhnk, K.D. ; Branco, P. ; Nes, E.H. van; Scheffer, M. ; Ellner, S.P. - \ 2008
Nature 451 (2008). - ISSN 0028-0836 - p. 822 - 825.
time-series - dynamics - cycles - phytoplankton - oscillations - models
Mathematical models predict that species interactions such as competition and predation can generate chaos1, 2, 3, 4, 5, 6, 7, 8. However, experimental demonstrations of chaos in ecology are scarce, and have been limited to simple laboratory systems with a short duration and artificial species combinations9, 10, 11, 12. Here, we present the first experimental demonstration of chaos in a long-term experiment with a complex food web. Our food web was isolated from the Baltic Sea, and consisted of bacteria, several phytoplankton species, herbivorous and predatory zooplankton species, and detritivores. The food web was cultured in a laboratory mesocosm, and sampled twice a week for more than 2,300 days. Despite constant external conditions, the species abundances showed striking fluctuations over several orders of magnitude. These fluctuations displayed a variety of different periodicities, which could be attributed to different species interactions in the food web. The population dynamics were characterized by positive Lyapunov exponents of similar magnitude for each species. Predictability was limited to a time horizon of 15¿30 days, only slightly longer than the local weather forecast. Hence, our results demonstrate that species interactions in food webs can generate chaos. This implies that stability is not required for the persistence of complex food webs, and that the long-term prediction of species abundances can be fundamentally impossible.
Energieproducerende Kas nog niet volledig benut
Zwart, H.F. de; Noort, F.R. van - \ 2008
Vakblad voor de Bloemisterij 63 (2008)3. - ISSN 0042-2223 - p. 38 - 40.
kassen - potplanten - energie - energieterugwinning - innovaties - nuttig gebruik - productiemogelijkheden - glastuinbouw - kastechniek - greenhouses - pot plants - energy - energy recovery - innovations - utilization - production possibilities - greenhouse horticulture - greenhouse technology
De Energieproducerende Kas by Hydro Huisman laat zien dat het concept werkt, maar dat een schaduwminnende potplantenteelt niet de beste teelt is voor een hoge netto-energieproductie. Een lichtminnend groentegewas en een lichtere kas zou een betere energieproductie hebben laten zien. Teelttechnisch gezien zijn de ervaringen overwegend positief
Het topsysteem van de ondergrond: Een reactievat. Deelrapport 5. Bruikbaarheid van reactiviteitsgegevens voor herleiden conserverend vermogen van de bodem m.b.t. archeologisch erfgoed
Klein, J. ; Griffioen, J. ; Huisman, D.J. ; Alterra - Centrum Landschap, - \ 2007
Utrecht : TNO-RACM - 25 p.
An airtight paddy storage system for small-scale farmers in Sri Lanka
Adhikarinayake, T.B. ; Müller, J. ; Oostdam, J.W.M. ; Huisman, W. ; Richards, P. - \ 2007
AMA: Agricultural Mechanization in Asia, Africa and Latin America 38 (2007)3. - ISSN 0084-5841 - p. 48 - 55.
The farmers in Sri Lanka's dry zone are the main contributors to the paddy production in the country. However, due to various reasons, they face difficulties in obtaining a reasonable income for their produce at harvesting time. According to the survey carried out in the paddy producing regions, it was found that one possible solution to reduce this problem is to enable the farmers to sell their produce at a time when prices are higher than at harvest time. To enable the farmers to keep their paddy on-farm for some time with a minimum loss of quality and quantity, some reliable and affordable storage facility has to be developed. To achieve this, an airtight storage system of 2.5 tons was developed by a four-step approach, which consists of: preliminary study to investigate the actual need, definition of the core problem, definition of the main function to be fulfilled by the designed system and finally, assessment of applicable working principles, to achieve a viable solution of the problem. This paper describes in detail the steps in the approach to achieve an efficient and inexpensive system acceptable to the farmers.
Tussenrapportage energie en teelt in de energieproducerende kas
Zwart, H.F. de; Noort, F. van; Bakker, J.C. - \ 2007
Wageningen : Wageningen UR Glastuinbouw (Nota / Wageningen UR Glastuinbouw 491) - 35
kassen - energie - energieterugwinning - productiemogelijkheden - transmissie - potplanten - gewaskwaliteit - glastuinbouw - greenhouses - energy - energy recovery - production possibilities - transmission - pot plants - crop quality - greenhouse horticulture
Tussenrapportage van de gewaskwaliteit in de energieproducerende kas bij Hydro Huisman om Huissen. Een lichtminnend groentegewas en een lichtere kas zou een betere energieproductie hebben laten zien. Vanuit teelttechnisch oogpunt zijn de ervaringen overwegend positief. Er is een behoorlijke teeltversnelling zichtbaar en de plantkwaliteit is voor de meeste beproefde soorten gelijk of wat beter. Voor een enkele soort is de kwaliteit wat minder
Onderzoek Energie Producerende Kas Stef Huisman - Bergerden (Huissen)
Noort, F.R. van; Zwart, H.F. de - \ 2007
kassen - energie - energiebehoud - teelt onder bescherming - glastuinbouw - greenhouses - energy - energy conservation - protected cultivation - greenhouse horticulture
Onderzoek van de Energieproducerende kas: nieuwe teeltmogelijkheden en bevindingen
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