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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An Evaluation of the Loss-on-Ignition Method for Determining the Soil Organic Matter Content of Calcareous Soils
Hoogsteen, M.J.J. ; Lantinga, E.A. ; Bakker, E.J. ; Tittonell, P.A. - \ 2018
Communications in Soil Science and Plant Analysis 48 (2018)13. - ISSN 0010-3624 - p. 1541 - 1552.
Calcite analysis procedures - ignition temperature - sample weight

The Loss-on-Ignition (LOI) method is widely employed for measuring the organic matter (OM) content of soil samples. There is a risk of carbonate losses when calcareous soil samples are analyzed through LOI, but this has never been investigated in detail. Moreover, a worldwide standard protocol for determining the carbonate content of soils is not available. The aims of this study were (i) to evaluate two commonly employed carbonate analysis procedures using calcareous and non-calcareous soil samples: the gravimetric method with (GMF) and without (GM) the addition of the antioxidant iron(II) chloride (FeCl2) and the acetic acid dissolution procedure (AAD); (ii) to evaluate the effect of ignition temperature on losses of pure calcite, calcite-quartz and calcareous soil samples. We found that the average apparent carbonate content of the non-calcareous soils was greatest for the GMF method followed by the AAD procedure. The GM method showed the smallest apparent carbonate contents. For the calcite-quartz sand mixture, ignition losses started at 600°C and increased with temperature in a sigmoidal way. LOI values stabilized at 750°C when 80% of the carbon dioxide was released. We recommend the GM procedure for carbonate analysis because the apparent carbonate contents of the non-calcareous soil samples were smallest. Furthermore, we recommend an LOI temperature of 550°C because at this ignition temperature 99.8% of the total calcite fraction remains in the soil samples.

Unravelling salutogenic mechanisms in the workplace : The role of learning
Pijpker, Roald ; Vaandrager, Lenneke ; Bakker, Evert Jan ; Koelen, Maria - \ 2018
Gaceta Sanitaria 32 (2018)3. - ISSN 0213-9111 - p. 275 - 282.
Cross-sectional survey - Effect modifier - Health promotion - Learning - Nurses - Sense of coherence - Workplace
Objective: To explore the moderating and mediating role(s) of learning within the relationship between sense of coherence (SOC) and generalized resistance resources. Method: Cross-sectional study (N = 481), using a self-administered questionnaire, of employees working in the healthcare sector in the Netherlands in 2017. Four residential healthcare settings and one healthcare-related Facebook group were involved. Multiple linear regression models were used to test for moderating and mediating effects of learning. Results: Social relations, task significance, and job control significantly explained variance in SOC. Conceptual, social, and instrumental learning, combined, moderated the relationship between SOC and task significance. Instrumental learning moderated the relationship between job control and SOC. Social learning also mediated this relationship. Conceptual learning did not show any moderating or mediating effect. Conclusions: The relationship between SOC and the three GRRs seems to be strengthened or explained. -to a certain extent. -by instrumental and social learning. Healthcare organizations are recommended to promote learning through formal activities as well as through cooperation, feedback, sharing experiences, and job challenges. This requires employee participation and a multilevel interdisciplinary approach.
Identification of determinants of postharvest losses in Zimbabwean tomato supply chains as basis for dedicated interventions
Macheka, L. ; Spelt, E.J.H. ; Bakker, E.J. ; Vorst, J.G.A.J. van der; Luning, P.A. - \ 2018
Food Control 87 (2018). - ISSN 0956-7135 - p. 135 - 144.
Postharvest losses (PHL) are a major problem in tomato supply chains, especially in tropical climates, as up to 40% of harvested fruits are estimated to decay along the chain. The study aimed at identifying which farmers' context characteristics, logistics and quality control activities relate with the generation of PHL in tomato supply chains, particularly in Zimbabwe. Commercial and subsistence tomato farmers (n = 197) from five major tomato-growing areas were analysed using a diagnostic tool to assess the status of logistics and quality control activities, the vulnerability of farmers' context, and the actual PHL. Hierarchical cluster analysis resulted in three clusters of farmers grouped based on similarities on context vulnerability and status of logistics and quality control activities. Spearman's rank correlation analysis and multiple linear regression analyses revealed that more advanced logistics and control activities, and context characteristics with a lower vulnerability to PHL are associated with less postharvest losses. The context characteristics, features of storage facilities, features of cropping system, and market price stability were significant determinants (p < .05) and explained 29% (Adjusted R2 = 0.287) of the variation in the PHL. The logistics control activity, determining processing volumes was identified as a possible determinant (p < .05) and explained 21% (Adjusted R2 = 0.205) of the variation in the observed PHL. The quality control activities, deciding on maturity to harvest, deciding on moment to harvest, and storage practices were the identified determinants (p < .05), which explained 23% (Adjusted R2 = 0.230) of the variability in the observed postharvest losses. A framework of intervention strategies tailored to tomato farmers' development stage is proposed to support them in a step-wise improvement of logistics and quality control practices to reduce PHL and advance towards more advanced supply chains.
Evaluation of field resistance to Striga hermonthica (Del.) Benth. in Sorghum bicolor (L.) Moench. The relationship with strigolactones
Mohemed Ahmed Mohamed, Nasr Eldin ; Charnikhova, Tatsiana ; Bakker, Evert J. ; Ast, Aad van; Babiker, Abdelgabar Gt ; Bouwmeester, Harro J. - \ 2016
Pest Management Science 72 (2016)11. - ISSN 1526-498X - p. 2082 - 2090.
Resistance - Sorghum - Striga - Strigolactones

BACKGROUND: Significant losses in sorghum biomass and grain yield occur in sub-Saharan Africa owing to infection by the root-parasitic weed Striga hermonthica (Del.) Benth. One strategy to avoid these losses is to adopt resistant crop varieties. For further delineation of the role of germination stimulants in resistance, we conducted a field experiment employing six sorghum genotypes, in eastern Sudan, and in parallel analysed the strigolactone levels in the root exudates of these genotypes under controlled conditions in Wageningen. RESULTS: The root exudates of these genotypes displayed large differences in strigolactone composition and Striga-germination-inducing activity. Korokollow, Fakimustahi and Wadfahel exuded the highest amounts of 5-deoxystrigol. Fakimustahi was by far the highest sorgomol producer, and Wadbaco and SRN39 produced the highest amount of orobanchol. The concentration of 5-deoxystrigol in the root exudate showed a significant positive correlation with in vitro Striga germination and was positively associated with Striga infection in the field experiments, whereas orobanchol was negatively associated with Striga infection in the field experiments. CONCLUSION: For the first time a close association is reported between strigolactone levels analysed under laboratory conditions and Striga infection in the field in sorghum genotypes. These genotypes may be used for further study of this resistance mechanism and for the introgression of the low germination trait in other sorghum varieties to breed for a strigolactone composition with low stimulant activity. The use of such improved varieties in combination with other Striga management tools could possibly alleviate the current Striga problem on the African continent.

Letter to the editor and rebuttal: Protein and amino acid bioavailability estimates for canine foods
Hendriks, W.H. ; Bakker, E.J. ; Bosch, G. - \ 2016
Journal of Animal Science 94 (2016)8. - ISSN 0021-8812 - p. 3121 - 3124.
Health-related quality of life, self-efficacy and enjoyment keep the socially vulnerable physically active in community-based physical activity programs: a sequential cohort study
Herens, M.C. ; Bakker, E.J. ; Ophem, J.A.C. van; Wagemakers, A. ; Koelen, M.A. - \ 2016
PLoS One 11 (2016)2. - ISSN 1932-6203
Physical inactivity is most commonly found in socially vulnerable groups. Dutch policies target these groups through community-based health-enhancing physical activity (CBHEPA) programs. As robust evidence on the effectiveness of this approach is limited, this study investigated whether CBHEPA programs contribute to an increase in and the maintenance of physical activity in socially vulnerable groups. In four successive cohorts, starting at a six-month interval, 268 participants from 19 groups were monitored for twelve months in seven CBHEPA programs. Data collection was based on repeated questionnaires. Socio-economic indicators, program participation and coping ability were measured at baseline. Physical activity, health-related quality of life and on-going program participation were measured three times. Self-efficacy and enjoyment were measured at baseline and at twelve months. Statistical analyses were based on a quasi-RCT design (independent t-tests), a comparison of participants and dropouts (Mann-Whitney test), and multilevel modelling to assess change in individual physical activity, including group level characteristics. Participants of CBHEPA programs are socially vulnerable in terms of low education (48.6%), low income (52.4%), non-Dutch origin (64.6%) and health-related quality of life outcomes. Physical activity levels were not below the Dutch average. No increase in physical activity levels over time was observed. The multilevel models showed significant positive associations between health-related quality of life, self-efficacy and enjoyment, and leisure-time physical activity over time. Short CBHEPA programs (10–13 weeks) with multiple trainers and gender-homogeneous groups were associated with lower physical activity levels over time. At twelve months, dropouts' leisure-time physical activity levels were significantly lower compared to continuing participants, as were health-related quality of life, self-efficacy and enjoyment outcomes. BMI and care consumption scored significantly higher among dropouts. In conclusion, Dutch CBHEPA programs reach socially vulnerable, but not necessarily inactive, groups in terms of socio-economic and health-related quality of life outcomes. Our findings suggest that CBHEPA programs particularly contribute to physical activity maintenance in socially vulnerable groups, rather than to an increase in physical activity behaviour over time.
Estimating soil organic carbon through loss on ignition : Effects of ignition conditions and structural water loss
Hoogsteen, M.J.J. ; Lantinga, E.A. ; Bakker, E.J. ; Groot, J.C.J. ; Tittonell, P.A. - \ 2015
European Journal of Soil Science 66 (2015)2. - ISSN 1351-0754 - p. 320 - 328.

Loss on ignition (LOI) is one of the most widely used methods for measuring organic matter content in soils but does not have a universal standard protocol. A large number of factors may influence its accuracy, such as furnace type, sample mass, duration and temperature of ignition and clay content of samples. We conducted a series of experiments to quantify these effects, which enabled us to derive (i) guidelines for ignition conditions (sample mass, duration and temperature), (ii) temperature-specific soil organic matter (SOM) to soil organic carbon (SOC) conversion factors and (iii) clay content-dependent correction factors for structural water loss (SWL). Bulk samples of a sandy soil (4% clay) and a silt loam soil (25% clay) were used to evaluate the effects of ignition conditions. Samples with a range of clay contents (0-50%) were used to quantify conversion and correction factors. Two furnaces, one without and one with pre-heated air, did not show significant differences in terms of within-batch LOI variability. In both furnaces less combustion occurred close to the door, which necessitated tray turning at half-time as this reduced the standard deviation per batch significantly. Variation in mass loss declined exponentially with sample mass (range, 0.15-20g). The LOI increased with duration at lower temperatures (≤550°C) for the sandy soil. At greater temperatures (600 and 650°C), no effect of duration was found. For the silt loam soil, LOI values increased with duration for each temperature, which was attributed to SWL. The SOM to SOC conversion factor decreased strongly with temperature at an ignition duration of 3hours from 0.70 (350°C) to 0.57 (500°C) and stabilized around 0.55 between 550 and 650°C, indicating that at temperatures ≥550°C all SOM had been removed. The clay correction factor for SWL increased from 0.01 to 0.09 as the temperature of ignition increased from 350 to 650°C. To minimize within-batch LOI variation we recommend a standard ignition duration of 3hours, tray turning at half-time, a sample mass ≥20g and temperatures equal to or greater than 550°C. To avoid over-estimates of SOM through structural water loss, the presented SWL correction procedure should always be applied.

Protein and amino acid bioavailability estimates for canine foods
Hendriks, W.H. ; Bakker, E.J. ; Bosch, G. - \ 2015
Journal of Animal Science 93 (2015)10. - ISSN 0021-8812 - p. 4788 - 4795.
Estimates of nutrient bioavailability are required for establishing dietary nutrient requirements and to evaluate the nutritional value of food ingredients or foods that are exposed to processing or extended storage. This study aimed to generate estimates for the bioavailability of dietary CP and AA for adult dogs using existing literature data and to evaluate the accuracy of estimates currently used in 3 authoritative publications. A regression equation was derived relating apparent fecal N outflow to standardized ileal N outflow from a data set containing information on 158 individual diets and their N digestibility when fed to adult dogs. Standardized ileal digestibility (sID) of N (sIDN) was shown to be nearly perfectly correlated to the sID of the sum of N of AA in 24 diets for which AA digestibility data were available. Regression equations between sID of individual AA and sIDN were calculated. Bioavailability estimates were subsequently derived from simulated sID values of N and essential and nonessential AA for 10 diets varying in CP content (18 to 42%) and apparent fecal N digestibility (70 and 80%) for an adult dog of 20 kg BW. Calculated bioavailability estimates of the NRC for maintenance dog foods do not lead to realistic nutrient allowance estimates for CP and AA. Estimates used by the Association of American Feed Control Officials and the European Pet Food Industry Federation were closer to calculated values, although the majority were too low, with the exception of CP, Arg, and Lys. Bioavailability estimates for Lys, Met, and Cys as calculated here require further veracity as the chemical form in which these AA are present in commercial pet foods may significantly reduce their bioavailability.
Health-related quality of life, self-efficacy and enjoyment keep the socially vulnerable physically active
Herens, M.C. ; Bakker, E.J. ; Ophem, J.A.C. van; Wagemakers, A. ; Vaandrager, L. ; Koelen, M. - \ 2015
Effect of frying instructions for food handlers on acrylamide concentration in French Fries: an explorative study
Sanny, M.A.I. ; Luning, P.A. ; Jinap, S. ; Bakker, E.J. ; Boekel, T. van - \ 2013
Journal of Food Protection 76 (2013)3. - ISSN 0362-028X - p. 462 - 472.
quality management research - techno-managerial approach - mu-g/kg acrylamide - service establishments - reducing sugars - safety - temperature - strategies - reduction - behavior
The objective of this study was to obtain insight into the effect of frying instructions on food handlers' control decisions in restaurants and to investigate the impact of control decisions on the variation and concentration of acrylamide in French fries. The concentrations of acrylamide and reducing sugars were analyzed, the frying temperature and time were measured, and thawing practices were observed. The results obtained before and after instructions were provided to the food handlers were compared for restaurants as a group and for each restaurant. Frying instructions supported food handlers' decisions to start frying when the oil temperature reached 175°C; all handlers started frying at the correct temperature. However, the effect of the instructions on the food handlers' decisions for frying time differed; most handlers increased the frying time beyond 240 s to achieve crispier French fries with a final color dictated by their preference. Providing instructions did not result in a significant difference in the mean concentration of acrylamide in French fries for the restaurants as a group. However, data analyzed for each restaurant revealed that when food handlers properly followed the instructions, the mean concentration of acrylamide was significantly lower (169 µg/kg) than that before instructions were provided (1,517 µg/kg). When food handlers did not complying with the frying instructions, mean acrylamide concentrations were even higher than those before instructions were provided. Two different strategies were developed to overcome the noncompliant behavior of food handlers: establishing requirements for the features of commercial fryers and strict monitoring of compliance with instructions.
The defecation pattern of healthy term infants up to the age of 3 months
Hertog, J. ; Leengoed, E. van; Kolk, F. ; Broek, L. van den; Kramer, E. ; Bakker, E.J. ; Bakker-van Gijssel, E. ; Bulk, A. ; Kneepkens, F. ; Benninga, M.A. - \ 2012
Arch. Dis. Child.-Fetal Neonatal Ed. 97 (2012)6. - ISSN 1359-2998 - p. F465 - F470.
double-blind - 1st stool - formula - frequency
Background Defecation problems occur frequently in infants. A clearer insight into the normal defecation pattern is required to gain a better understanding of abnormal defecation. Aim To describe the defecation pattern of healthy infants in The Netherlands. Methods From a research population of 1175 healthy Dutch infants, 600 infants without any complaints were selected. The parents recorded details of feeding and defecation at the age of 1, 2 and 3 months using a standardised questionnaire and bowel diary. Results In breastfed infants, average daily defecation frequency decreased significantly during the first 3 months (from 3.65 to 1.88 times per day), whereas no significant changes were observed in infants fed standard formula or mixed feeding. At every age both the average and the range of defecation frequency of breastfed infants were higher than those of infants receiving formula feeding. Breastfed infants had softer faeces than formula-fed infants and the colour more often was yellow. At the age of 3 months, 50% of stools of formula-fed infants were green coloured. There was no significant difference in quantity between the three types of feeding, but there existed a negative correlation between defecation frequency and quantity. Conclusion This study gives insight into the defecation patterns of the largest cohort of healthy infants published so far. In the first 3 months of life, breastfed infants have more frequent, softer and more yellow-coloured stools than standard formula-fed infants. Green-coloured stools in standard formula-fed infants should be considered normal.
Possible causes of variation in acrylamide concentration in French fries prepared in food service establishments: an observational study
Sanny, M.A.I. ; Jinap, S. ; Bakker, E.J. ; Boekel, M.A.J.S. van; Luning, P.A. - \ 2012
Food Chemistry 132 (2012)1. - ISSN 0308-8146 - p. 134 - 143.
techno-managerial approach - mu-g/kg acrylamide - maillard reaction - risk-assessment - quality - potatoes - asparagine - chips - fat - glucose
Acrylamide is a probable human carcinogen, and its presence in a range of fried and oven-cooked foods has raised considerable health concern world-wide. Dietary intake studies observed significant variations in acrylamide concentrations, which complicate risk assessment and the establishment of effective control measures. The objective of this study was to obtain an insight into the actual variation in acrylamide concentrations in French fries prepared under typical conditions in a food service establishment (FSE). Besides acrylamide, frying time, frying temperature, and reducing sugars were measured and the actual practices at receiving, thawing and frying during French fries preparation were observed and recorded. The variation in the actual frying temperature contributed most to the variation in acrylamide concentrations, followed by the variation in actual frying time; no obvious effect of reducing sugars was found. The lack of standardised control of frying temperature and frying time (due to inadequate frying equipment) and the variable practices of food handlers seem to contribute most to the large variation and high acrylamide concentrations in French fries prepared in a restaurant type of FSE as compared to chain fast-food services, and institutional caterers. The obtained insights in this study can be used to develop dedicated control measures in FSE, which may contribute to a sustainable reduction in the acrylamide intake.
Is lowering reducing sugars concentration in French fries an effective measure to reduce acrylamide concentration in food service establishments?
Sanny, M.A.I. ; Jinap, S. ; Bakker, E.J. ; Boekel, M.A.J.S. van; Luning, P.A. - \ 2012
Food Chemistry 135 (2012)3. - ISSN 0308-8146 - p. 2012 - 2020.
mu-g/kg acrylamide - risk-assessment - potatoes - temperature - asparagine - strategies - formation/elimination - exposure - kinetics - options
The objective of this study was to obtain insight into the actual effectiveness of lowering reducing sugars concentration in par-fried potato strips on the concentration and variation of acrylamide in French fries prepared in real-life situations in food service establishments. Acrylamide, frying time, frying temperature, and reducing sugars were measured and characteristics of fryers were recorded. Data showed that the use of par-fried potato strips with lower concentrations of reducing sugars than the commonly used potato strips was an effective measure to reduce acrylamide concentrations in French fries prepared under standardised frying conditions. However, there was still large variation in the acrylamide concentrations in French fries, although the variation in reducing sugars concentrations in low and normal types of par-fried potato strips was very small and the frying conditions were similar. Factors that could affect the temperature–time profile of frying oil were discussed, such as setting a lower frying temperature at the end than at the start of frying, product/oil ratio and thawing practice. These need to be controlled in daily practice to reduce variation in acrylamide.
Plant-soil feedback: Experimental approaches, statistical analyses and biological interpretations
Brinkman, E.P. ; Putten, W.H. van der; Bakker, E.J. ; Verhoeven, K.J.F. - \ 2010
Journal of Ecology 98 (2010)5. - ISSN 0022-0477 - p. 1063 - 1073.
vesicular-arbuscular mycorrhiza - grass ammophila-arenaria - community - diversity - pathogens - growth - succession - nematodes - dynamics - biota
1. Feedback between plants and soil organisms has become widely recognized as a driving force of community composition and ecosystem functioning. However, there is little uniformity in quantification and analysis of plant–soil feedback effects. Meta-analysis suggested that the various experimental methods tend to result in different feedback values. Yet, a direct comparison of the different experimental approaches and their statistical analyses is lacking. 2. We used currently applied methods to calculate plant–soil feedback value ranges and compared their statistical analyses to those based on actual biomass data. Then, we re-analysed a case study to compare plant–soil feedback values obtained under the same environmental conditions, but using different experimental approaches: soil sterilization, addition of soil inoculum, and soil conditioning by ‘own’ vs. ‘foreign’ plant species. 3. Different measures to calculate plant–soil feedback values were more variable in positive than in negative feedback values. Analysis of calculated feedback values that are based on treatment averages can lead to a serious inflation of type I errors. 4. In our case study, both the strength and the direction of the feedback effects depended on the experimental approach that was chosen, leading to diverging conclusions on whether feedback to a certain soil was positive or negative. Soil sterilization and addition of soil organisms yielded larger feedback than comparison of own and foreign soil. 5. Synthesis. The ecological interpretation of plant–soil feedback effects strongly depends on the experimental procedure. When the research question focuses on the strength and the sign of plant–soil feedback, soil sterilization (presumed that the side effect of increased nutrient availability can be controlled) or addition of soil inoculum is to be preferred. When the research question concerns the specificity of soil feedback effects, plant performance can be better compared between own and foreign soil. We recommend that when using calculated feedback values, the original data need to be presented as well in order to trace the cause of the effect.
Meta-analysis of Supramaximal Effects in In Vitro Estrogenicity Assays
Montano, M. ; Bakker, E.J. ; Murk, A.J. - \ 2010
Toxicological sciences 115 (2010)2. - ISSN 1096-6080 - p. 462 - 474.
breast-cancer-cells - gfp expression system - green fluorescent protein - receptor-alpha - bisphenol-a - er-alpha - mcf-7 cells - environmental chemicals - response elements - gene-expression
In scientific literature, several estrogenic compounds are reported to induce responses in vitro that are significantly higher than that of estradiol (E2). These supramaximal (SPMX) estrogenic effects do not occur consistently and seem to differ depending on the cellular models applied. This study analyzes the possible underlying causes, mechanisms, and drivers for SPMX estrogenic effects in in vitro functional assays reported in the peer-reviewed literature. For the 21 natural and industrial chemicals identified as SPMX inducers, the culture and exposure conditions varied greatly among and between the assays. Detailed information on assay characteristics, however, sometimes lacked. Diethylstilbestrol, genistein, and bisphenol A were selected to build a database. The meta-analysis revealed that the occurrence of SPMX effects could be related to a number of specific assay characteristics: (1) the type of serum used to supplement the exposure medium, (2) the end point used to quantify the estrogenic potency (endogenous or transfected), (3) the number of estrogen response elements, and (4) and the promoter's nature. An SPMX response was not reported for expression of endogenous genes, assays that used African green monkey kidney (COS-1) cell line or with chloramphenicol transferase as the reporter gene. There were no indications that solvent concentration in culture, exposure period, or cell model influenced the occurrence of an SPMX effect. It is important to understand the mechanism behind this phenomenon because in vitro assays for estrogenicity are used extensively to characterize and quantify the estrogenic potency of compounds, mixtures and environmental extracts.
Homeopathy as replacement to antibiotics in the case of Escherichia coli diarrhoea in neonatal piglets
Camerlink, I. ; Ellinger, L. ; Bakker, E.J. ; Lantinga, E.A. - \ 2010
Homeopathy 99 (2010)1. - ISSN 1475-4916 - p. 57 - 62.
veterinary practice
Background The use of antibiotics in the livestock sector is increasing to such an extent that it threatens negative consequences for human health, animal health and the environment. Homeopathy might be an alternative to antibiotics. It has therefore been tested in a randomised placebo-controlled trial to prevent Escherichia coli diarrhoea in neonatal piglets. Method On a commercial pig farm 52 sows of different parities, in their last month of gestation, were treated twice a week with either the homeopathic agent Coli 30K or placebo. The 525 piglets born from these sows were scored for occurrence and duration of diarrhoea. Results Piglets of the homeopathic treated group had significantly less E. coli diarrhoea than piglets in the placebo group (P <.0001). Especially piglets from first parity sows gave a good response to treatment with Coli 30K. The diarrhoea seemed to be less severe in the homeopathically treated litters, there was less transmission and duration appeared shorter.
Effects of processing parameters on the iron and zinc solubility of infant sorghum porridge
Kayodé, A.P.P. ; Linnemann, A.R. ; Bakker, E.J. ; Hounhouigan, J.D. ; Nout, M.J.R. ; Boekel, T. van - \ 2008
A framework to identify appropriate spatial and temporal scales for modeling N flows from watersheds
Dumont, E.L. ; Bakker, E.J. ; Bouwman, L. ; Kroeze, C. ; Leemans, R. ; Stein, A. - \ 2008
Ecological Modelling 212 (2008)3-4. - ISSN 0304-3800 - p. 256 - 272.
seine river - quality - time - uncertainty - sensitivity - landscapes - dimensions - management - fluxes - space
We describe a framework (FAMOS) to identify the appropriate spatial and temporal scales for nitrogen (N) flow models. FAMOS has been developed for models of N export from large watersheds. With FAMOS, modelers can identify the appropriate scale for model predictions and for independently scalable model parts. FAMOS is based upon four criteria to check the appropriateness of modeling scales. Modeling scales thus have to correspond with (A) data and scenarios, (B) model assumptions, (C) available resources for modeling, and (D) appropriately scaled predictions. We present 12 indicators to test these criteria. A user of FAMOS may use all or a selection of these, to identify the appropriateness of a modeling scale for his purpose. The indicators vary between 0 and 1 as a function of scale, and are to be quantified and weighted by the user. A successful application of FAMOS is illustrated for a global model of dissolved inorganic nitrogen (DIN) export from watersheds to coastal waters. Ranges of appropriate scales are determined for model predictions and five independently scalable model parts, which model the (1) surface N balance, (2) point sources, (3) N flow in sediments and small streams, (4) retention in dammed reservoirs, and (5) riverine DIN retention. We conclude that FAMOS can contribute substantially to a well-balanced and comprehensive identification of appropriate modeling scales.
Effects of processing parameters on the iron and zinc solubility of infant sorghum porridge
Kayodé, A.P.P. ; Linnemann, A.R. ; Bakker, E.J. ; Hounhouigan, J.D. ; Nout, M.J.R. ; Boekel, M.A.J.S. van - \ 2007
In: Proceedings of the IFS Workshop: Traditional grains for low environmental impact and good health, Pretoria, South Africa, 5 - 8 November, 2007. - Pretoria : IFS, SIK, University of Pretoria - p. 4 - 4.
Fish consumption, n-3 fatty acids and colorectal cancer: a meta-analysis of prospective cohort studies
Schouten, J.M. ; Kamphuis, C. ; Stam, B.E. ; Burema, J. ; Renkema, J.M.S. ; Bakker, E.J. ; Veer, P. van 't; Kampman, E. - \ 2007
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