|System Analysis in AIS: Potentials and Pitfalls
Schut, M. ; Roo, N. de; Salomons, M. ; Beshah, T. ; Hawkins, R. - \ 2017
Response to habitat modification by foraging Dark-chanting Goshawks Melierax metabates in a West African savanna
Buij, Ralph ; Dorst, Nikie Van; Salomons, Henriëtte F. ; Croes, Barbara M. ; Dietz, Maurine W. ; Komdeur, Jan - \ 2015
Bird Conservation International 25 (2015)3. - ISSN 0959-2709 - p. 335 - 352.
Anthropogenic habitat alteration has probably contributed significantly to the decrease of raptor populations in West African savannas. To evaluate the impact of habitat degradation on foraging by sedentary Afrotropical raptors, we investigated the differences in microhabitat selection, foraging effort and energy returns between Dark-chanting Goshawks Melierax metabates inhabiting natural and transformed savannas in Cameroon. We expected that the agro-ecosystems in the transformed savannas have become unprofitable for Dark-chanting Goshawks due to scarcity of food resources. In both savanna types we radio-tracked six mated, adult males during the non-breeding season and determined foraging effort, by time spent at each perch and distance covered between perches, and energy intake through estimation of the energy value of prey items. Goshawks in natural habitats had smaller home-ranges and exploited their range more intensively than Goshawks in transformed habitats. In both natural and transformed habitats, Goshawks selected foraging patches with comparatively tall trees, underlining their importance to foraging Goshawks. The extent of shrub and herbaceous layer cover, agriculture cover, and tree density were other important predictors of foraging patch use, but their importance differed between habitats. The extent of shrub, herbaceous layer and agriculture cover were positively associated with foraging patch use in transformed habitats, suggesting that cultivated fields and ground vegetation support important prey resources for Goshawks in agro-ecosystems. The composition of broad prey categories to the diet, foraging effort and returns were comparable between habitats. However, we found indications that the proportion of heavy-bodied lizard species among reptile prey items was higher in natural than transformed habitats, whereas on average smaller lizards were more commonly caught in the latter. Mean herbaceous layer height and tree density within home ranges, both higher in natural habitat, were negatively related to prey capture rates. Tree clearance and livestock grazing thus favored greater prey capture rates in transformed habitat, offsetting a lower meal energy value compared to natural habitat. We conclude that foraging Dark-chanting Goshawks may cope with moderate land transformation, but practices focused on conservation of tall trees and ground vegetation cover would be beneficial by maintaining important prey resources and their exploitability under growing land pressure.
Stochastic modelling of length-dependent telomere shortening in Corvus monedula
Grasman, J. ; Salomons, H.M. ; Verhulst, S. - \ 2011
Journal of Theoretical Biology 282 (2011)1. - ISSN 0022-5193 - p. 1 - 6.
oxidative stress - replicative senescence - cellular senescence - human fibroblasts - human-cells - life-span - accumulation - dynamics - survival - mortality
It was recently shown that, within individuals, longer telomeres shorten at a higher rate. This explorative study deals with a mathematical model of this process. It is a nonlinear differential equation describing length-dependent decrease that can be linked to a Poisson process. The model also takes in account telomere shortening due to the end replication problem. Parameters are fitted using data from samples of red blood cells of free-living juvenile corvids. The Poisson process can be related to oxidative stress causing DNA strand breaks. The shortest telomeres in a genome are the best predictors of survival, and one can therefore hypothesize on functional grounds that short telomeres should be better protected by some control mechanism in the cellular system. However, the present study shows that such a mechanism is not required to explain length-dependent telomere shortening: agents of telomere shortening such as oxidative stress with a certain strength modeled by a Poisson process with an appropriately chosen parameter suffice to generate the observed pattern
Cd, Cu and Zn solubility in arable forest soils: consequences of land use changes for metal mobility and risk assessment
Römkens, P.F.A.M. ; Salomons, W. - \ 1998
Soil Science 163 (1998)11. - ISSN 0038-075X - p. 859 - 871.
|Global change: economic and social impact and responses in coastal systems: The Netherlands LOICZ Programme Implementation Plan Focus 4.
Bergh, C.J.M. van den; Groot, R.S. de; Heip, C.H.R. ; Herman, P.J. ; Leeuw, J.W. de; Salomons, W. ; Visser, L.E. ; Vries, I. de - \ 1998
Climate control of natural ventilated pig houses
Bontsema, J. ; Straten, G. van; Salomons, L. ; Klooster, C.E. van 't - \ 1996
In: II IFAC/ISHS Workshop : Mathematical & Control Applications in Agriculture & Horticulture / Day, W., Young, P.C., - p. 81 - 88.
Ventilation in pig houses is important for maintaining a good climate for the welfare of animals and humans and for an optimal production. Mechanical ventilation has a good performance, since the ventilation rate can easily be controlled, but it is energy demanding, whereas natural ventilation is cheap but due to large variations in the outdoor conditions it can cause unwanted variations in the ventilation rate. To improve the performance of natural ventilation a good control scheme is necessary. Since in this case controller tuning is difficult in the practical situation, due to all influences on the climate, a dynamic model is discussed, so that the tuning can be done off-line, which means that the tuning of the controllers is done in simulations. The model of the indoor climate is validated by measurements of the temperature of the pig house. The performance of the control scheme, in which standard PID controllers are used in a cascade configuration, is shown by simulations.
|Interaction between calcium and dissolved organic carbon: implications for metal mobilization
Römkens, P.F. ; Bril, J. ; Salomons, W. - \ 1996
Applied Geochemistry 11 (1996). - ISSN 0883-2927 - p. 109 - 115.
Dynamic model to tune a climate control algorithm in pig houses with natural ventilation
Klooster, C.E. van 't; Bontsema, J. ; Salomons, L. - \ 1995
Transactions of the ASAE 38 (1995). - ISSN 0001-2351 - p. 911 - 918.
Algorithms for environmental control in livestock buildings have to be tuned for optimum response of actuators. For tuning, a simple, but dynamic, climate model for a pig house was formulated and validated to predict the
environmental changes in a pig house with natural ventilation under varying conditions, A control algorithm was included in the model and tuning of the algorithm has been performed with the model. The tuned algorithm was
implemented in a climate controller and data on the results are presented. It was concluded that the model can be used to simulate room temperature and carbon dioxide concentration in heated pig houses with natural ventilation. The dynamics as well as the actual levels of climate parameters showed agreement between simulation results and actual results. The model can be used to find gain factors and time constants for PID-controllers in algorithms for control of room temperature, air quality, and ventilation rate in natural ventilated pig houses. This would enhance fast and accurate tuning controllers in livestock buildings with natural ventilation as compared to on-site hand tuning.
Keywords. Natural ventilation. Control, Model, Swine.
|Time-delayed responses of chemicals in soils. A case for chemical time bombs?
Salomons, W. ; Bril, J. ; Römkens, P.F. - \ 1995
In: Int. Conference on diffuse (non-point) pollution, Chicago
|The non-applicability of the simple Kd-approach in modelling trace metal behaviour: a field study
Römkens, P.F. ; Salomons, W. - \ 1995
In: Heavy metals in the environment. Conference Proceedings, Toronto, part 2 - p. 496 - 499.
|Kinetic control of the biogeochemical formation of halogenated humic acids
Dolfing, J. ; Salomons, W. - \ 1995
In: Naturally-produced organohalogens / Grimvall, A., de Leer, E.W.B., Dordrecht : Kluwer - p. 221 - 223.
Seasonal and spatial variation of heavy metal solubilities in a fallow, acidic loamy sand loam
Castilho, P. del; Blaauw, D. ; Salomons, W. - \ 1993
In: Integrated soil and sediment research : a basis for proper protection : selected proceedings of the first European conference on integrated research for soil and sediment protection and remediation (EUROSOL), held in Maastricht, 6 - 12 September 1992 / Eijsackers, H.J.P., Hamers, T., Kluwer (Soil & environment vol. 1) - p. 255 - 256.
bodemoplossing - bodem - zware metalen - zure gronden - kattekleigronden - soil solution - soil - heavy metals - acid soils - acid sulfate soils
Time delayed responses of chemicals in soils
Salomons, W. - \ 1993
In: Contaminated soils : risks and remedies, proceedings - p. 1 - 18.
zware metalen - metaalelementen - bodem - heavy metals - metallic elements - soil
Influence of cattle manure slurry application on the solubility of cadmium, copper, and zinc in a manured acidic, loamy sand soil
Castilho, P. ; Chardon, W.J. ; Salomons, W. - \ 1993
Journal of Environmental Quality 22 (1993)4. - ISSN 0047-2425 - p. 689 - 697.
stalmest - zware metalen - bodem - farmyard manure - heavy metals - soil
A management model to assess the extent of movement of chemicals through soils
Bril, J. ; Postma, L. - \ 1993
In: Chemical time bombs : proceedings of the European state-of-the-art conference on delayed effects of chemical in soils and sediments, Veldhoven, the Netherlands, 2 - 5 September 1992 / ter Meulen, G.R.B., Stigliani, W.M., Salomons, W., Stichting Mondiaal Alternatief - p. 181 - 194.
infiltratie - hydraulisch geleidingsvermogen - kwel - absorptie - adsorptie - modellen - onderzoek - infiltration - hydraulic conductivity - seepage - absorption - adsorption - models - research
A model for the movement of chemicals in soils, STRASS (Simulation of TRansport and Sorption in Soils) based on the numerical solution to the one-dimensional convection-dispersion equation is presented in this study
Our fathers' toxic sins
Stigliani, W. ; Salomons, W. - \ 1993
New Scientist (1993)1903. - ISSN 0262-4079 - p. 38 - 42.
For decades we have dumped toxic chemicals in the soil without a second thought. But there is a reckoning on the way.
|Trace metals in the environment: modelling of long-term processes affecting mobility/bio-availability. Report on a workshop
Römkens, P.F. ; Knoop, J. ; Salomons, W. - \ 1993
Diffuse bronnen in de landbouw
Salomons, W. ; Stol, B.E.M. - \ 1992
Haren Gr. : DLO-Instituut voor Bodemvruchtbaarheid (Rapport / DLO-Instituut voor Bodemvruchtbaarheid ) - 88
landbouw - milieu - nadelige gevolgen - milieueffect - kunstmeststoffen - mest - gewasbescherming - pesticiden - agriculture - environment - adverse effects - environmental impact - fertilizers - manures - plant protection - pesticides
Chemical time bombs: predicting the unpredictable.
Stigliani, W.M. ; Doelman, P. ; Salomons, W. ; Schulin, R. ; Schmidt, G.R.B. ; Zee, S.E.A.T.M. van der - \ 1991
Environment: Science and Policy for Sustainable Development 33 (1991)4. - ISSN 0013-9157 - p. 4 - 30.
|Chemical time bombs: definition, concepts and examples.
Doelman, P. ; Salomons, W. ; Schulin, R. ; Schmidt, G.R.B. ; Stigliani, W.M. ; Zee, S.E.A.T.M. van der - \ 1991
Unknown Publisher - 30 p.