Relative Validity of the HELIUS Food Frequency Questionnaire for Measuring Dietary Intake in Older Adult Participants of the Longitudinal Aging Study Amsterdam
Visser, Marjolein ; Elstgeest, Liset E.M. ; Winkens, Laura H.H. ; Brouwer, Ingeborg A. ; Nicolaou, Mary - \ 2020
Nutrients 12 (2020)7. - ISSN 2072-6643
24-hour recall - diet assessment - elderly - FFQ - validation
The aim of this study was to determine the relative validity of the HEalthy LIfe in an Urban Setting (HELIUS) food frequency questionnaire (FFQ) in assessing the dietary intake of energy, nutrients, and food groups of Dutch older men and women. In 2014-2015, 88 participants of the Longitudinal Aging Study Amsterdam aged 71.9 (SD 8.6) years completed the 238-item HELIUS FFQ and three 24-hour dietary recalls. The mean group-level bias in the intakes of energy, nutrients, and food groups between the two methods was assessed, as well as Pearson's correlation coefficients and level of agreement using quintile distribution. For the intakes of energy and macronutrients, the group-level bias was ≤5%, Pearson's correlation coefficients were moderate to good (ranging from 0.26 for total fat to 0.72 for alcohol), and agreement was moderate to high (classification in same or adjacent quintile ranging from 63% for energy, protein, and carbohydrate to 91% for alcohol). For most micronutrients and food groups, the relative validity was moderate (Pearson's correlation coefficients between 0.3 and 0.5), with the lowest correlations for β-carotene (0.08), vitamin B1 (0.19), fish (0.14), and grains (0.24). In conclusion, for energy and macronutrients, most micronutrients, and most food groups, the relative validity of the HELIUS FFQ to assess dietary intake in Dutch older adults was acceptable to good.
How to compare sampling designs for mapping?
Wadoux, Alexandre M.J.C. ; Brus, Dick J. - \ 2020
European Journal of Soil Science (2020). - ISSN 1351-0754
Kriging - machine learning - pedometrics - random forest - soil sampling - validation
If a map is constructed through prediction with a statistical or non-statistical model, the sampling design used for selecting the sample on which the model is fitted plays a key role in the final map accuracy. Several sampling designs are available for selecting these calibration samples. Commonly, sampling designs for mapping are compared in real-world case studies by selecting just one sample for each of the sampling designs under study. In this study, we show that sampling designs for mapping are better compared on the basis of the distribution of the map quality indices over repeated selection of the calibration sample. In practice this is only feasible by subsampling a large dataset representing the population of interest, or by selecting calibration samples from a map depicting the study variable. This is illustrated with two real-world case studies. In the first case study a quantitative variable, soil organic carbon, is mapped by kriging with an external drift in France, whereas in the second case a categorical variable, land cover, is mapped by random forest in a region in France. The performance of two sampling designs for mapping are compared: simple random sampling and conditioned Latin hypercube sampling, at various sample sizes. We show that in both case studies the sampling distributions of map quality indices obtained with the two sampling design types, for a given sample size, show large variation and largely overlap. This shows that when comparing sampling designs for mapping on the basis of a single sample selected per design, there is a serious risk of an incidental result. Highlights: We provide a method to compare sampling designs for mapping. Random designs for selecting calibration samples should be compared on the basis of the sampling distribution of the map quality indices.
Simultaneous Analysis of Glucosinolates and Isothiocyanates by Reversed-Phase Ultra-High-Performance Liquid Chromatography-Electron Spray Ionization-Tandem Mass Spectrometry
Andini, Silvia ; Araya-Cloutier, Carla ; Sanders, Mark ; Vincken, Jean Paul - \ 2020
Journal of Agricultural and Food Chemistry 68 (2020)10. - ISSN 0021-8561 - p. 3121 - 3131.
dithiocarbamate - glucosinolate breakdown product - LC-MS analysis - mustard - thioglucosidase - validation
A new method to simultaneously analyze various glucosinolates (GSLs) and isothiocyanates (ITCs) by reversed-phase ultra-high-performance liquid chromatography-electron spray ionization-tandem mass spectrometry has been developed and validated for 14 GSLs and 15 ITCs. It involved derivatization of ITCs with N-acetyl-l-cysteine (NAC). The limits of detection were 0.4-1.6 μM for GSLs and 0.9-2.6 μM for NAC-ITCs. The analysis of Sinapis alba, Brassica napus, and Brassica juncea extracts spiked with 14 GSLs and 15 ITCs indicated that the method generally had good intraday (≤10% RSD) and interday precisions (≤16% RSD). Recovery of the method was unaffected by the extracts and within 71-110% for GSLs and 66-122% for NAC-ITCs. The method was able to monitor the enzymatic hydrolysis of standard GSLs to ITCs in mixtures. Furthermore, GSLs and ITCs were simultaneously determined in Brassicaceae plant extracts before and after myrosinase treatment. This method can be applied to further investigate the enzymatic conversion of GSLs to ITCs in complex mixtures.
Field data of "Monitoring forest phenology and leaf area index with the autonomous, low-cost transmittance sensor PASTiS-57"
Brede, Benjamin ; Gastellu-Etchegorry, Jean Philippe ; Lauret, Nicolas ; Baret, Frederic ; Clevers, Jan ; Verbesselt, Jan ; Herold, Martin - \ 2020
Wageningen University & Research
forest - ground-based - Land Surface Phenology - Leaf Area Index - validation
Land Surface Phenology (LSP) and Leaf Area Index (LAI) are important variables that describe the photosynthetically active phase and capacity of vegetation. Both are derived on the global scale from optical satellite sensors and require robust validation based on in situ sensors at high temporal resolution. This study assesses the PAI Autonomous System from Transmittance Sensors at 57? (PASTiS-57) instrument as a low-cost transmittance sensor for simultaneous monitoring of LSP and LAI in forest ecosystems. In a field experiment, spring leaf flush and autumn senescence in a Dutch beech forest were observed with PASTiS-57 and illumination independent, multi-temporal Terrestrial Laser Scanning (TLS) measurements in five plots. Both time series agreed to less than a day in Start Of Season (SOS) and End Of Season (EOS). LAI magnitude was strongly correlated with a Pearson correlation coefficient of 0.98. PASTiS-57 summer and winter LAI were on average 0.41m2m-2 and 1.43m2m-2 lower than TLS. This can be explained by previously reported overestimation of TLS. Additionally, PASTiS-57 was implemented in the Discrete Anisotropic Radiative Transfer (DART) Radiative Transfer Model (RTM) model for sensitivity analysis. This confirmed the robustness of the retrieval with respect to non-structural canopy properties and illumination conditions. Generally, PASTiS-57 fulfilled the CEOS LPV requirement of 20% accuracy in LAI for a wide range of biochemical and illumination conditions for turbid medium canopies. However, canopy non-randomness in discrete tree models led to strong biases. Overall, PASTiS-57 demonstrated the potential of autonomous devices for monitoring of phenology and LAI at daily temporal resolution as required for validation of satellite products that can be derived from ESA Copernicus’ optical missions, Sentinel-2 and -3.
Evaluating the ecological realism of plant species distribution models with ecological indicator values
Hellegers, Marjon ; Ozinga, Wim A. ; Hinsberg, Arjen ; Huijbregts, Mark A.J. ; Hennekens, Stephan M. ; Schaminée, Joop H.J. ; Dengler, Jürgen ; Schipper, Aafke M. - \ 2020
Ecography 43 (2020)1. - ISSN 0906-7590 - p. 161 - 170.
BioScore - ecological niche model - Ellenberg indicator values - model selection - scale dependency - validation
Species distribution models (SDMs) are routinely applied to assess current as well as future species distributions, for example to assess impacts of future environmental change on biodiversity or to underpin conservation planning. It has been repeatedly emphasized that SDMs should be evaluated based not only on their goodness of fit to the data, but also on the realism of the modeled ecological responses. However, possibilities for the latter are hampered by limited knowledge on the true responses as well as a lack of quantitative evaluation methods. Here we compared modeled niche optima obtained from European-scale SDMs of 1476 terrestrial vascular plant species with empirical ecological indicator values indicating the preferences of plant species for key environmental conditions. For each plant species we first fitted an ensemble SDM including three modeling techniques (GLM, GAM and BRT) and extracted niche optima for climate, soil, land use and nitrogen deposition variables with a large explanatory power for the occurrence of that species. We then compared these SDM-derived niche optima with the ecological indicator values by means of bivariate correlation analysis. We found weak to moderate correlations in the expected direction between the SDM-derived niche optima and ecological indicator values. The strongest correlation occurred between the modeled optima for growing degree days and the ecological indicator values for temperature. Correlations were weaker for SDM-derived niche optima with a more distal relationship to ecological indicator values (notably precipitation and soil moisture). Further, correlations were consistently highest for BRT, followed by GLM and GAM. Our method gives insight into the ecological realism of modeled niche optima and projected core habitats and can be used to improve SDMs by making a more informed selection of environmental variables and modeling techniques.
Risk assessment of exotic disease incursion and spread
Cabral, M. ; Taylor, R. ; Vos, C.J. de - \ 2019
EFSA Journal 17 (2019)S2. - ISSN 1831-4732
generic model - Import risk assessment - introduction risk - livestock disease - validation
This Technical Report describes the activities developed in the scope of the EU-FORA Fellowship, within the work programme of risk assessment (RA) of exotic disease incursion and spread, developed at Wageningen Bioveterinary Research (WBVR). The programme focused on the work carried out in the Generic risk assessment for introduction of animal diseases (G-RAID) project, which brings together a number of different generic RA tools from multiple European partners. The aim of the fellowship was to gain understanding of veterinary import risk assessment by using different RA tools and to learn how different algorithms can be used to calculate disease incursion risks. G-RAID's tools cover a wide range of RA methodologies; from purely qualitative, to semi-quantitative and fully stochastic quantitative methods, which allowed the fellow to understand a variety of algorithms used to produce the final risk estimate. The fellowship programme provided the fellow with the chance to learn in detail about how generic RAs are performed across Europe, understanding how to deal with the uncertainty and variability involved in RAs and the potential problems of data availability and reliability. The fellow made an inventory of publicly available databases on disease occurrence and international trade that could be used for import RA and assessed their quality and usefulness for the different generic RA tools. The programme also provided the fellow the opportunity to perform several import risk assessments using the RA tools of G-RAID. She completed a RA on African swine fever using the MINTRISK model developed by WBVR. Furthermore, she assessed the risk of foot and mouth disease introduction using the Rapid Risk Assessment Tool (RRAT) model developed by WBVR and the COMPARE model developed by the Animal and Plant Health Agency (APHA). To this end, the fellow completed a short-term visit to APHA, enabling her to have additional training in quantitative RA and to expand her professional network in this area.
Evaluation of Mycotoxin Screening Tests in a Verification Study Involving First Time Users
Lattanzio, Veronica M.T. ; Holst, Christoph von; Lippolis, Vincenzo ; Girolamo, Annalisa De; Logrieco, Antonio F. ; Mol, Hans G.J. ; Pascale, Michelangelo - \ 2019
Toxins 11 (2019)2. - ISSN 2072-6651 - 18 p.
cereals - immunoassay - mass spectrometry - mycotoxins - screening - validation
(AFB₁) in maize and wheat using LFD and LC-HRMS, respectively. The results of analyses were used to calculate intermediate precision (RSDip, covering the inter-analyst variability in preparing the analytical samples and the precision under repeatability conditions) cut-off values and false suspect rates. RSDip ranged from 6.5% to 30% for DON, and from 16% to 33% for AFB₁. The highest obtained variances were associated with the AFB₁ analyses due to working with much lower mass fractions. The rate of false suspect results were lower than 0.1% for all tested methods. All methods showed a fit-for-purpose method performance profile, which allowed a clear distinction of samples containing the analytes at the screening target concentration (STC) from negative control samples. Moreover, the first time users obtained method performances similar to those obtained for validation studies previously performed on the screening methods included in the training course.
Pooling of genital swabs for detection by PCR of Taylorella equigenitalis, the cause of contagious equine metritis
Mawhinney, I. ; Errington, J. ; Stamper, N. ; Torrens, N. ; Engelsma, M.Y. ; Roest, H.I.J. - \ 2019
Equine Veterinary Journal 51 (2019)2. - ISSN 0425-1644 - p. 227 - 230.
diagnosis - horse - infection - validation
Background: Sets of genital swabs are routinely taken from horses to screen for the presence of Taylorella equigenitalis, the cause of contagious equine metritis. Typically, two to four different sites are swabbed at a time and tested by culture or PCR. Objectives: This study explored the feasibility of pooling these swabs for a single PCR test per animal instead of testing each swab individually. Study design: In vitro. Methods: PCR signal strengths (Ct values) from 149 historical PCR positive genital swabs, together with historical data on the number of swabs in a set expected to be positive, were used to assess the suitability of pooling for screening horses for T. equigenitalis infection in the population at large. Twenty-four sets of four equine genital swabs were tested. The sets were prepared in the laboratory using one or more swabs positive for T. equigenitalis from naturally infected cases. Positive and negative swabs were selected to reflect a typical range of PCR Ct values expected in field cases of T. equigenitalis infection. These pools were tested by an established PCR to assess the impact and suitability of a PCR test on pooled swabs compared to individual swab testing, by comparing the Ct values. Results: Pooling one positive swab with three negative swabs produced a small drop in Ct value but all pools were still clearly positive. Main limitations: Large numbers of field positive horses are not available, but the proof of concept approach with laboratory prepared pools shows the method is applicable to field cases. Conclusions: It was concluded that pooling of swabs would confer no appreciable drop in the ability to detect a positive animal compared to individual swab testing; pooling is therefore a suitable alternative to individual swab testing with reduced costs. The Summary is available in Spanish – see Supporting Information.
Validation of a mathematical model of the bovine estrous cycle for cows with different estrous cycle characteristics
Boer, H.M.T. ; Butler, S.T. ; Stötzel, C. ; Pas, M.F.W. te; Veerkamp, R.F. ; Woelders, H. - \ 2017
Animal 11 (2017)11. - ISSN 1751-7311 - p. 1991 - 2001.
bovine - estrous cycle - mathematical model - parameter identification - validation
A recently developed mechanistic mathematical model of the bovine estrous cycle was parameterized to fit empirical data sets collected during one estrous cycle of 31 individual cows, with the main objective to further validate the model. The a priori criteria for validation were (1) the resulting model can simulate the measured data correctly (i.e. goodness of fit), and (2) this is achieved without needing extreme, probably non-physiological parameter values. We used a least squares optimization procedure to identify parameter configurations for the mathematical model to fit the empirical in vivo measurements of follicle and corpus luteum sizes, and the plasma concentrations of progesterone, estradiol, FSH and LH for each cow. The model was capable of accommodating normal variation in estrous cycle characteristics of individual cows. With the parameter sets estimated for the individual cows, the model behavior changed for 21 cows, with improved fit of the simulated output curves for 18 of these 21 cows. Moreover, the number of follicular waves was predicted correctly for 18 of the 25 two-wave and three-wave cows, without extreme parameter value changes. Estimation of specific parameters confirmed results of previous model simulations indicating that parameters involved in luteolytic signaling are very important for regulation of general estrous cycle characteristics, and are likely responsible for differences in estrous cycle characteristics between cows.
Development and validation of the Axiom®Apple480K SNP genotyping array
Bianco, Luca ; Cestaro, Alessandro ; Linsmith, Gareth ; Muranty, Hélène ; Denancé, Caroline ; Théron, Anthony ; Poncet, Charles ; Micheletti, Diego ; Kerschbamer, Emanuela ; Pierro, Erica A. Di; Larger, Simone ; Pindo, Massimo ; De Weg, Eric Van; Davassi, Alessandro ; Laurens, François ; Velasco, Riccardo ; Durel, Charles Eric ; Troggio, Michela - \ 2016
The Plant Journal 86 (2016)1. - ISSN 0960-7412 - p. 62 - 74.
genome-wide association study - genotyping - linkage mapping - Malus × domestica Borkh. - SNP chip - validation
Cultivated apple (Malus × domestica Borkh.) is one of the most important fruit crops in temperate regions, and has great economic and cultural value. The apple genome is highly heterozygous and has undergone a recent duplication which, combined with a rapid linkage disequilibrium decay, makes it difficult to perform genome-wide association (GWA) studies. Single nucleotide polymorphism arrays offer highly multiplexed assays at a relatively low cost per data point and can be a valid tool for the identification of the markers associated with traits of interest. Here, we describe the development and validation of a 487K SNP Affymetrix Axiom® genotyping array for apple and discuss its potential applications. The array has been built from the high-depth resequencing of 63 different cultivars covering most of the genetic diversity in cultivated apple. The SNPs were chosen by applying a focal points approach to enrich genic regions, but also to reach a uniform coverage of non-genic regions. A total of 1324 apple accessions, including the 92 progenies of two mapping populations, have been genotyped with the Axiom®Apple480K to assess the effectiveness of the array. A large majority of SNPs (359 994 or 74%) fell in the stringent class of poly high resolution polymorphisms. We also devised a filtering procedure to identify a subset of 275K very robust markers that can be safely used for germplasm surveys in apple. The Axiom®Apple480K has now been commercially released both for public and proprietary use and will likely be a reference tool for GWA studies in apple.
Monitoring forest cover loss using multiple data streams, a case study of a tropical dry forest in Bolivia
Dutrieux, L.P. ; Verbesselt, J. ; Kooistra, L. ; Herold, M. - \ 2015
ISPRS Journal of Photogrammetry and Remote Sensing 107 (2015). - ISSN 0924-2716 - p. 112 - 125.
landsat time-series - structural-change - vegetation indexes - rainfall products - detecting trends - east-africa - amazon - disturbance - validation - modis
Automatically detecting forest disturbances as they occur can be extremely challenging for certain types of environments, particularly those presenting strong natural variations. Here, we use a generic structural break detection framework (BFAST) to improve the monitoring of forest cover loss by combining multiple data streams. Forest change monitoring is performed using Landsat data in combination with MODIS or rainfall data to further improve the modelling and monitoring. We tested the use of the Normalized Difference Vegetation Index (NDVI) from the Moderate Resolution Imaging Spectroradiometer (MODIS) with varying spatial aggregation window sizes as well as a rainfall derived index as external regressors. The method was evaluated on a dry tropical forest area in lowland Bolivia where forest cover loss is known to occur, and we validated the results against a set of ground truth samples manually interpreted using the TimeSync environment. We found that the addition of an external regressor allows to take advantage of the difference in spatial extent between human induced and naturally induced variations and only detect the processes of interest. Of all configurations, we found the 13 by 13 km MODIS NDVI window to be the most successful, with an overall accuracy of 87%. Compared with a single pixel approach, the proposed method produced better time-series model fits resulting in increases of overall accuracy (from 82% to 87%), and decrease in omission and commission errors (from 33% to 24% and from 3% to 0% respectively). The presented approach seems particularly relevant for areas with high inter-annual natural variability, such as forests regularly experiencing exceptional drought events.
Evaluation of Satellite Rainfall Estimates for Drought and Flood Monitoring in Mozambique
Tote, C. ; Patricio, D. ; Boogaard, H.L. ; Wijngaart, R. van der; Tarnavsky, E. ; Funk, C. - \ 2015
Remote Sensing 7 (2015)2. - ISSN 2072-4292 - p. 1758 - 1776.
west-africa - precipitation - validation - products - microwave - climate - dataset - gages - sahel - trmm
Satellite derived rainfall products are useful for drought and flood early warning and overcome the problem of sparse, unevenly distributed and erratic rain gauge observations, provided their accuracy is well known. Mozambique is highly vulnerable to extreme weather events such as major droughts and floods and thus, an understanding of the strengths and weaknesses of different rainfall products is valuable. Three dekadal (10-day) gridded satellite rainfall products (TAMSAT African Rainfall Climatology And Time-series (TARCAT) v2.0, Famine Early Warning System NETwork (FEWS NET) Rainfall Estimate (RFE) v2.0, and Climate Hazards Group InfraRed Precipitation with Stations (CHIRPS)) are compared to independent gauge data (2001–2012). This is done using pairwise comparison statistics to evaluate the performance in estimating rainfall amounts and categorical statistics to assess rain-detection capabilities. The analysis was performed for different rainfall categories, over the seasonal cycle and for regions dominated by different weather systems. Overall, satellite products overestimate low and underestimate high dekadal rainfall values. The RFE and CHIRPS products perform as good, generally outperforming TARCAT on the majority of statistical measures of skill. TARCAT detects best the relative frequency of rainfall events, while RFE underestimates and CHIRPS overestimates the rainfall events frequency. Differences in products performance disappear with higher rainfall and all products achieve better results during the wet season. During the cyclone season, CHIRPS shows the best results, while RFE outperforms the other products for lower dekadal rainfall. Products blending thermal infrared and passive microwave imagery perform better than infrared only products and particularly when meteorological patterns are more complex, such as over the coastal, central and south regions of Mozambique, where precipitation is influenced by frontal systems.
Loss of Olfactory Function and Nutritional Status in Vital Older Adults and Geriatric Patients
Toussaint, N. ; Roon, M. de; Campen, J.P.C.M. van; Kremer, S. ; Boesveldt, S. - \ 2015
Chemical Senses 40 (2015)3. - ISSN 0379-864X - p. 197 - 203.
mild cognitive impairment - odor identification - normative data - taste - malnutrition - smell - discrimination - dysfunction - prevalence - validation
The aim of this cross-sectional study was to assess the association of olfactory function and nutritional status in vital older adults and geriatric patients. Three hundred forty-five vital (mean age 67.1 years) and 138 geriatric older adults (mean age 80.9 years) were included. Nutritional status was assessed using the mini nutritional assessment-short form. The Sniffin’ Sticks was used to measure olfactory function. Eleven percentage of the vital older adults were at risk of malnutrition, whereas 60% of the geriatric participants were malnourished or at risk. Only 2% of the vital older adults were anosmic, compared with 46% of the geriatric participants. Linear regression demonstrated a significant association (P = 0.015) between olfactory function and nutritional status in the geriatric subjects. However, this association became insignificant after adjustment for confounders. Both crude and adjusted analysis in the vital older adults did not show a significant association. The results indicate that, in both groups of elderly, there is no direct relation between olfactory function and nutritional status. We suggest that a decline in olfactory function may still be considered as one of the risk-factors for malnutrition in geriatric patients—once co-occurring with other mental and/or physical problems that are more likely to occur in those patients experience.
Surface water risk assessment of pesticides in Ethiopia
Teklu, B.M. ; Adriaanse, P.I. ; Horst, M.M.S. ter; Deneer, J.W. ; Brink, P.J. van den - \ 2015
Science of the Total Environment 508 (2015). - ISSN 0048-9697 - p. 566 - 574.
predict insecticide concentrations - models fail - field - validation - exposure
Scenarios for future use in the pesticide registration procedure in Ethiopia were designed for 3 separate Ethiopian locations, which are aimed to be protective for the whole of Ethiopia. The scenarios estimate concentrations in surface water resulting from agricultural use of pesticides for a small stream and for two types of small ponds. Seven selected pesticides were selected since they were estimated to bear the highest risk to humans on the basis of volume of use, application rate and acute and chronic human toxicity, assuming exposure as a result of the consumption of surface water. Potential ecotoxicological risks were not considered as a selection criterion at this stage. Estimates of exposure concentrations in surface water were established using modelling software also applied in the EU registration procedure (PRZM and TOXSWA). Input variables included physico-chemical properties, and data such as crop calendars, irrigation schedules, meteorological information and detailed application data which were specifically tailored to the Ethiopian situation. The results indicate that for all the pesticides investigated the acute human risk resulting from the consumption of surface water is low to negligible, whereas agricultural use of chlorothalonil, deltamethrin, endosulfan and malathion in some crops may result in medium to high risk to aquatic species. The predicted environmental concentration estimates are based on procedures similar to procedures used at the EU level and in the USA. Addition of aquatic macrophytes as an ecotoxicological endpoint may constitute a welcome future addition to the risk assessment procedure. Implementation of the methods used for risk characterization constitutes a good step forward in the pesticide registration procedure in Ethiopia. KEYWORDS: Aquatic ecosystems; Drinking water; Ecological risk assessment; Ethiopia; Exposure modelling; Pesticides; Tropics
Probabilistic networks of blood metabolites in healthy subjects as indicators of latent cardiovascular risk
Saccenti, E. ; Suarez Diez, M. ; Luchinat, C. ; Santucci, C. ; Tenori, L. - \ 2015
Journal of Proteome Research 14 (2015)2. - ISSN 1535-3893 - p. 1101 - 1111.
l-arginine supplementation - gene-coexpression network - insulin-resistance - metabolomic networks - disease - obesity - expression - cholesterol - association - validation
The complex nature of the mechanisms behind cardiovascular diseases prevents the detection of latent early risk conditions. Network representations are ideally suited to investigate the complex interconnections between the individual components of a biological system underlying complex diseases. Here we investigate the patterns of correlations of an array of 29 metabolites identified and quantified in the plasma of 864 healthy blood donors and use a systems biology approach to define metabolite probabilistic networks specific for low and high latent cardiovascular risk. We adapted methods based on the likelihood of correlation and methods from information theory and combined them with resampling techniques. Our results show that plasma metabolite networks can be defined that associate with latent cardiovascular disease risk. The analysis of the networks supports our previous finding of a possible association between cardiovascular risk and impaired mitochondrial activity and highlights post-translational modifications (glycosilation and oxidation) of lipoproteins as a possible target-mechanism for early detection of latent cardiovascular risk.
Multi-model radiometric slope correction of SAR images of complex terrain using a two-stage semi-empirical approach
Hoekman, D.H. ; Reiche, J. - \ 2015
Remote Sensing of Environment 156 (2015). - ISSN 0034-4257 - p. 1 - 10.
radar imagery - topography - forest - classification - backscatter - validation
Practical approaches for the implementation of terrain type dependent radiometric slope correction for SAR data are introduced. Radiometric slope effects are modelled as the products of two models. The first is a simple physical model based on the assumption of a uniform opaque layer of isotropic scatterers, which is independent of terrain type, frequency and polarization. It accounts for the slope-induced variation in the number of scatterers per resolution cell. The second is a semi-empirical model, which accounts for the variation in scattering mechanisms, dependent on terrain type, frequency and polarization. PALSAR FBD (L-band, HH- and HV-polarization) data are used at two test sites in Brazil and Fiji. Results for the Brazilian area, which has slopes up to 25°, show that remaining slope effects for the multi-model case are much smaller than 0.1 dB, for all land cover types. This is much better than the best single-model approach where remaining slope effects can be very small for forests but be as large as 1.77 dB for woodland in HH-polarization. Results for the Fiji area, which has different vegetation types, are very similar. The potential large improvement, using this multi-model approach, in the accuracy of biomass estimation for transparent or open canopies is discussed. It is also shown that biomass change on slopes can be systematically under- or overestimated because of associated change in scattering mechanism.
Comparison of approaches to correct intake-health association for FFQ measurement eroor using a duplicate recovery biomarker and a duplicate 24h dietary recall as reference method
Geelen, A. ; Souverein, O.W. ; Busstra, M.C. ; Vries, J.H.M. de; Veer, P. van 't - \ 2015
Public Health Nutrition 18 (2015)2. - ISSN 1368-9800 - p. 226 - 233.
episodically consumed foods - european centers - urinary nitrogen - potassium intake - validation - cancer - nutrition - protein - questionnaires - individuals
Objective To illustrate the impact of intake-related bias in FFQ and 24 h recall (24hR), and correlated errors between these methods, on intake–health associations. Design Dietary intake was assessed by a 180-item semi-quantitative FFQ and two 24hR. Urinary N and urinary K were estimated from two 24 h urine samples. We compared four scenarios to correct associations for errors in an FFQ estimating protein and K intakes. Setting Wageningen, The Netherlands. Subjects Fifty-nine men and fifty-eight women aged 45–65 years. Results For this FFQ, measurement error weakened a true relative risk of 2·0 to 1·4 for protein and 1·5 for K. As compared with calibration to duplicate recovery biomarkers (i.e. the preferred scenario 1), estimating a validity coefficient using this duplicate biomarker resulted in overcorrected associations, caused by intake-related bias in the FFQ (scenario 2). The correction factor based on a triad using biomarkers and 24hR was hampered by this intake-related bias and by correlated errors between FFQ and 24hR, and in this population resulted in a nearly perfect correction for protein but an overcorrection for K (scenario 3). When the 24hR was used for calibration, only a small correction was done, due to correlated errors between the methods and intake-related bias in the 24hR (scenario 4). Conclusions Calibration to a gold standard reference method is the preferred approach to correct intake–health associations for FFQ measurement error. If it is not possible to do so, using the 24hR as reference method only partly removes the errors, but may result in improved intake–health associations.
Moisture transport in swelling media modelled with a Lattice Boltzmann scheme having a deforming lattice
Sman, R.G.M. van der - \ 2014
Journal of Food Engineering 124 (2014). - ISSN 0260-8774 - p. 54 - 63.
non-brownian suspensions - diffusion lattice - water transport - flow - simulations - profiles - kinetics - food - gels - validation
In this paper we present a novel numerical scheme for simulating the one-dimensional deformation of hydrogel material due to drying or rehydration. The scheme is based on the versatile Lattice Boltzmann method, which has been extended such that the computational grid (lattice) deforms due to shrinkage or swelling. This property of a deforming grid is new to the lattice Boltzmann method, and a detailed description of this new method is given. Via simulations we show that self-similar moisture concentration profiles occur in two periods in both drying and swelling processes: the penetration period and the regular regime. Given the property of self-similarity, we have been able to formulate a reduced-order model for the regular regime of swelling.
The Wageningen Lowland Runoff Simulator (WALRUS): application to the Hupsel Brook catchement and Cabauw polder
Brauer, C.C. ; Torfs, P.J.J.F. ; Teuling, A.J. ; Uijlenhoet, R. - \ 2014
Hydrology and Earth System Sciences 18 (2014). - ISSN 1027-5606 - p. 4007 - 4028.
surface parameterization schemes - distributed hydrological model - flow route contributions - land-surface - groundwater interactions - spatial variability - rainfall - scale - netherlands - validation
The Wageningen Lowland Runoff Simulator (WALRUS) is a new parametric (conceptual) rainfall–runoff model which accounts explicitly for processes that are important in lowland areas, such as groundwater-unsaturated zone coupling, wetness-dependent flowroutes, groundwater–surface water feedbacks, and seepage and surface water supply (see companion paper by Brauer et al., 2014). Lowland catchments can be divided into slightly sloping, freely draining catchments and flat polders with controlled water levels. Here, we apply WALRUS to two contrasting Dutch catchments: the Hupsel Brook catchment and the Cabauw polder. In both catchments, WALRUS performs well: Nash–Sutcliffe efficiencies obtained after calibration on 1 year of discharge observations are 0.87 for the Hupsel Brook catchment and 0.83 for the Cabauw polder, with values of 0.74 and 0.76 for validation. The model also performs well during floods and droughts and can forecast the effect of control operations. Through the dynamic division between quick and slow flowroutes controlled by a wetness index, temporal and spatial variability in groundwater depths can be accounted for, which results in adequate simulation of discharge peaks as well as low flows. The performance of WALRUS is most sensitive to the parameter controlling the wetness index and the groundwater reservoir constant, and to a lesser extent to the quickflow reservoir constant. The effects of these three parameters can be identified in the discharge time series, which indicates that the model is not overparameterised (parsimonious). Forcing uncertainty was found to have a larger effect on modelled discharge than parameter uncertainty and uncertainty in initial conditions.
Status quo and future research challenges on organic food quality determination with focus on laboratory methods
Kahl, J. ; Bodroza-Solarov, M. ; Busscher, N. ; Hajslova, J. ; Kneifel, W. ; Kokornaczyk, M.O. ; Ruth, S.M. van; Schulzova, V. ; Stolz, P. - \ 2014
Journal of the Science of Food and Agriculture 94 (2014)13. - ISSN 0022-5142 - p. 2595 - 2599.
wheat-grain leakages - grown winter-wheat - nutritional quality - crystallization patterns - samples - standardization - authentication - definition - validation - products
Organic food quality determination needs multi-dimensional evaluation tools. The main focus is on the authentication as an analytical verification of the certification process. New fingerprinting approaches such as ultra-performance liquid chromatography–mass spectrometry, gas chromatography–mass spectrometry, direct analysis in real time–high-resolution mass spectrometry as well as crystallization with and without the presence of additives seem to be promising methods in terms of time of analysis and detecting organic system-related parameters. For further methodological development, a system approach is recommended, which also takes into account food structure aspects. Furthermore, the authentication of processed organic samples needs more consciousness, hence most of organic food is complex and processed.
Fast and nondestructive method for leaf level chlorophyll estimation using hyperspectral LiDAR
Nevalainen, O. ; Hakala, T. ; Suomalainen, J.M. ; Mäkipää, R. ; Peltoniemi, M. ; Krooks, A. ; Kaasalainen, S. - \ 2014
Agricultural and Forest Meteorology 198-199 (2014). - ISSN 0168-1923 - p. 250 - 258.
supercontinuum laser source - vegetation indexes - reflectance spectra - precision agriculture - canopy reflectance - red edge - airborne - model - spectroscopy - validation
We propose an empirical method for nondestructive estimation of chlorophyll in tree canopies. The first prototype of a full waveform hyperspectral LiDAR instrument has been developed by the Finnish Geodetic Institute (FGI). The instrument efficiently combines the benefits of passive and active remote sensing sensors. It is able to produce 3D point clouds with spectral information included for every point, which offers great potential in the field of environmental remote sensing. The investigation was conducted by using chlorophyll sensitive vegetation indices applied to hyperspectral LiDAR data and testing their performance in chlorophyll estimation. The amount of chlorophyll in vegetation is an important indicator of photosynthetic capacity and stress, and thus important for monitoring of forest condition and carbon sequestration on Earth. Performance of chlorophyll estimation was evaluated for 27 published vegetation indices applied to waveform LiDAR collected from ten Scots pine shoots. Reference data were collected by laboratory chlorophyll concentration analysis. The performance of the indices in chlorophyll estimation was determined by linear regression and leave-one-out cross-validation. The chlorophyll estimates derived from hyperspectral LiDAR linearly correlate with the laboratory analyzed chlorophyll concentrations, and they are able to represent a range of chlorophyll concentrations in Scots pine shoots (R2 = 0.88, RMSE = 0.10 mg/g). Furthermore, they are insensitive to measurement scale as nearly the same values of vegetation indices were measured in natural setting while scanning the whole canopy and from clipped shoots re-measured with hyperspectral LiDAR in laboratory. The results indicate that the hyperspectral LiDAR instrument has the potential to estimate vegetation biochemical parameters such as the chlorophyll concentration. The instrument holds much potential in various environmental applications and provides a significant improvement over single wavelength LiDAR or passive optical systems for environmental remote sensing.
Genomic prediction based on data from three layer lines using non-linear regression models
Huang, H. ; Windig, J.J. ; Vereijken, A. ; Calus, M.P.L. - \ 2014
Genetics, Selection, Evolution 46 (2014). - ISSN 0999-193X - 11 p.
dairy-cattle breeds - dimensionality reduction - gaussian kernel - accuracy - traits - values - validation - selection - pedigree - plant
Background - Most studies on genomic prediction with reference populations that include multiple lines or breeds have used linear models. Data heterogeneity due to using multiple populations may conflict with model assumptions used in linear regression methods. Methods - In an attempt to alleviate potential discrepancies between assumptions of linear models and multi-population data, two types of alternative models were used: (1) a multi-trait genomic best linear unbiased prediction (GBLUP) model that modelled trait by line combinations as separate but correlated traits and (2) non-linear models based on kernel learning. These models were compared to conventional linear models for genomic prediction for two lines of brown layer hens (B1 and B2) and one line of white hens (W1). The three lines each had 1004 to 1023 training and 238 to 240 validation animals. Prediction accuracy was evaluated by estimating the correlation between observed phenotypes and predicted breeding values. Results - When the training dataset included only data from the evaluated line, non-linear models yielded at best a similar accuracy as linear models. In some cases, when adding a distantly related line, the linear models showed a slight decrease in performance, while non-linear models generally showed no change in accuracy. When only information from a closely related line was used for training, linear models and non-linear radial basis function (RBF) kernel models performed similarly. The multi-trait GBLUP model took advantage of the estimated genetic correlations between the lines. Combining linear and non-linear models improved the accuracy of multi-line genomic prediction. Conclusions - Linear models and non-linear RBF models performed very similarly for genomic prediction, despite the expectation that non-linear models could deal better with the heterogeneous multi-population data. This heterogeneity of the data can be overcome by modelling trait by line combinations as separate but correlated traits, which avoids the occasional occurrence of large negative accuracies when the evaluated line was not included in the training dataset. Furthermore, when using a multi-line training dataset, non-linear models provided information on the genotype data that was complementary to the linear models, which indicates that the underlying data distributions of the three studied lines were indeed heterogeneous.
Fusion of pan-tropical biomass maps using weighted averaging and regional calibration data
Ge, Y. ; Avitabile, V. ; Heuvelink, G.B.M. ; Wang, J. ; Herold, M. - \ 2014
International Journal of applied Earth Observation and Geoinformation 31 (2014). - ISSN 0303-2434 - p. 13 - 24.
remotely-sensed imagery - land-cover datasets - multisensor data - forest biomass - carbon-dioxide - sensing data - soil maps - classification - deforestation - validation
Biomass is a key environmental variable that influences many biosphere–atmosphere interactions. Recently, a number of biomass maps at national, regional and global scales have been produced using different approaches with a variety of input data, such as from field observations, remotely sensed imagery and other spatial datasets. However, the accuracy of these maps varies regionally and is largely unknown. This research proposes a fusion method to increase the accuracy of regional biomass estimates by using higher-quality calibration data. In this fusion method, the biases in the source maps were first adjusted to correct for over- and underestimation by comparison with the calibration data. Next, the biomass maps were combined linearly using weights derived from the variance–covariance matrix associated with the accuracies of the source maps. Because each map may have different biases and accuracies for different land use types, the biases and fusion weights were computed for each of the main land cover types separately. The conceptual arguments are substantiated by a case study conducted in East Africa. Evaluation analysis shows that fusing multiple source biomass maps may produce a more accurate map than when only one biomass map or unweighted averaging is used.
Nutrient-rich foods, cardiovascular diseases and all-cause mortality: the Rotterdam study
Streppel, M.T. ; Sluik, D. ; Yperen, J. van; Geelen, A. ; Hofman, A. ; Franco, O.H. ; Witteman, J.C.M. ; Feskens, E.J.M. - \ 2014
European Journal of Clinical Nutrition 68 (2014). - ISSN 0954-3007 - p. 741 - 747.
nutritional quality index - physical-activity - dietary pattern - elderly-people - women - risk - questionnaire - validation - cohort
Background/Objectives: The nutrient-rich food (NRF) index assesses nutrient quality of individual food items by ranking them according to their nutrient composition. The index reflects the nutrient density of the overall diet. We examined the associations between the NRF9.3 index—a score on the basis of nine beneficial nutrients (protein, fiber, vitamins and minerals) and three nutrients to limit (saturated fat, sugar and sodium)—incidence of cardiovascular disease (CVD) events and all-cause mortality. Subjects/Methods: A total of 4969 persons aged 55 and older from the Rotterdam Study, a prospective cohort study in the Netherlands, were studied. First, all foods were scored on the basis of their nutrient composition, resulting in an NRF9.3 score on food item level. Subsequently, they were converted into individual weighted scores on the basis of the amount of calories of each food item consumed by the subjects and the total energy intake. The hazard ratios (HRs) of the NRF9.3 index score were adjusted for age, gender, body mass index, smoking history, doctor-prescribed diet, alcohol consumption and education. Results: Food groups that contributed most to the NRF9.3 index score were vegetables, milk and milk products, fruit, bread and potatoes. A high NRF9.3 index score was inversely associated with all-cause mortality (HR Q4 versus Q1: 0.84 (95% confidence interval: 0.74, 0.96)). Associations were stronger in women than in men. The NRF9.3 index score was not associated with incidence of CVD. Conclusion: Elderly with a higher NRF9.3 index score, indicating more beneficial components and/or less limiting components, had a lower risk of all-cause mortality. Consuming a nutrient-dense diet may improve survival
Rapid analysis of Delta-9-tetrahydrocannabinol in hair using direct analysis in real time ambient ionization orbitrap mass spectrometry
Duvivier, W.F. ; Beek, T.A. van; Pennings, E.J.M. ; Nielen, M.W.F. - \ 2014
Rapid Communications in Mass Spectrometry 28 (2014)7. - ISSN 0951-4198 - p. 682 - 690.
synthetic cannabinoids - cocaine - drugs - identification - capabilities - metabolites - validation - samples - abuse
RATIONALE - Forensic hair analysis methods are laborious, time-consuming and provide only a rough retrospective estimate of the time of drug intake. Recently, hair imaging methods using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) were reported, but these methods require the application of MALDI matrix and are performed under vacuum. Direct analysis of entire locks of hair without any sample pretreatment and with improved spatial resolution would thus address a need. METHODS - Hair samples were attached to stainless steel mesh screens and scanned in the X-direction using direct analysis in real time (DART) ambient ionization orbitrap MS. The DART gas temperature and the accuracy of the probed hair zone were optimized using ¿-9-tetrahydrocannabinol (THC) as a model compound. Since external contamination is a major issue in forensic hair analysis, sub-samples were measured before and after dichloromethane decontamination. RESULTS - The relative intensity of the THC signal in spiked blank hair versus that of quinine as the internal standard showed good reproducibility (26% RSD) and linearity of the method (R2¿=¿0.991). With the DART hair scan THC could be detected in hair samples from different chronic cannabis users. The presence of THC was confirmed by quantitative liquid chromatography/tandem mass spectrometry. Zones with different THC content could be clearly distinguished, indicating that the method might be used for retrospective timeline assessments. Detection of THC in decontaminated drug user hair showed that the DART hair scan not only probes THC on the surface of hair, but penetrates deeply enough to measure incorporated THC. CONCLUSIONS - A new approach in forensic hair analysis has been developed by probing complete locks of hair using DART-MS. Longitudinal scanning enables detection of incorporated compounds and can be used as pre-screening for THC without sample preparation. The method could also be adjusted for the analysis of other drugs of abuse.
Evaluation of preformance of Predictive Models for Deoxynivalenol in Wheat
Fels, H.J. van der - \ 2014
Risk Analysis 34 (2014)2. - ISSN 0272-4332 - p. 380 - 390.
fusarium mycotoxins - winter-wheat - validation
The aim of this study was to evaluate the performance of two predictive models for deoxynivalenol contamination of wheat at harvest in the Netherlands, including the use of weather forecast data and external model validation. Data were collected in a different year and from different wheat fields than data used for model development. The two models were run for six preset scenarios, varying in the period for which weather forecast data were used, from zero-day (historical data only) to a 13-day period around wheat flowering. Model predictions using forecast weather data were compared to those using historical data. Furthermore, model predictions using historical weather data were evaluated against observed deoxynivalenol contamination of the wheat fields. Results showed that the use of weather forecast data rather than observed data only slightly influenced model predictions. The percent of correct model predictions, given a threshold of 1,250 µg/kg (legal limit in European Union), was about 95% for the two models. However, only three samples had a deoxynivalenol concentration above this threshold, and the models were not able to predict these samples correctly. It was concluded that two- week weather forecast data can reliable be used in descriptive models for deoxynivalenol contamination of wheat, resulting in more timely model predictions. The two models are able to predict lower deoxynivalenol contamination correctly, but model performance in situations with high deoxynivalenol contamination needs to be further validated. This will need years with conducive environmental conditions for deoxynivalenol contamination of wheat.
A high-throughput method for GMO multi-detection using a microfluidic dynamic array
Brod, F.C.A. ; Dijk, J.P. van; Voorhuijzen, M.M. ; Dinon, A.Z. ; Guimarães, L.H.S. ; Scholtens, I.M.J. ; Arisi, A.C.M. ; Kok, E.J. - \ 2014
Analytical and Bioanalytical Chemistry 406 (2014)5. - ISSN 1618-2642 - p. 1397 - 1410.
genetically-modified maize - real-time pcr - polymerase-chain-reaction - modified organisms - reference molecules - quantitative pcr - screening-assay - digital pcr - zea-mays - validation
The ever-increasing production of genetically modified crops generates a demand for high-throughput DNAbased methods for the enforcement of genetically modified organisms (GMO) labelling requirements. The application of standard real-time PCR will become increasingly costly with the growth of the number of GMOs that is potentially present in an individual sample. The present work presents the results of an innovative approach in genetically modified crops analysis byDNA basedmethods, which is the use of a microfluidic dynamic array as a high throughput multi-detection system. In order to evaluate the system, six test samples with an increasing degree of complexity were prepared, preamplified and subsequently analysed in the Fluidigm system. Twenty-eight assays targeting different DNA elements, GM events and species-specific reference genes were used in the experiment. The large majority of the assays tested presented expected results. The power of low level detection was assessed and elements present at concentrations as low as 0.06 % were successfully detected. The approach proposed in this work presents the Fluidigm system as a suitable and promising platform for GMO multi-detection.
Global water resources affected by human interventionss and climate change
Haddeland, I. ; Heinke, J. ; Biemans, H. ; Eisner, S. ; Florke, M.F. ; Hanasaki, N. ; Konzmann, M. ; Ludwig, F. - \ 2014
Proceedings of the National Academy of Sciences of the United States of America 111 (2014)9. - ISSN 0027-8424 - p. 3251 - 3256.
integrated model - bias correction - surface-water - validation - fluxes - scheme
Humans directly change the dynamics of the water cycle through dams constructed for water storage, and through water withdrawals for industrial, agricultural, or domestic purposes. Climate change is expected to additionally affect water supply and demand. Here, analyses of climate change and direct human impacts on the terrestrial water cycle are presented and compared using a multimodel approach. Seven global hydrological models have been forced with multiple climate projections, and with and without taking into account impacts of human interventions such as dams and water withdrawals on the hydrological cycle. Model results are analyzed for different levels of global warming, allowing for analyses in line with temperature targets for climate change mitigation. The results indicate that direct human impacts on the water cycle in some regions, e.g., parts of Asia and in the western United States, are of the same order of magnitude, or even exceed impacts to be expected for moderate levels of global warming (+2 K). Despite some spread in model projections, irrigation water consumption is generally projected to increase with higher global mean temperatures. Irrigation water scarcity is particularly large in parts of southern and eastern Asia, and is expected to become even larger in the future.
Skill of a global seasonal streamflow forecasting system, relative roles of initial conditions and meteorological forcing
Yossef, N.C. ; Winsemius, H. ; Weerts, A.H. ; Beek, R. van; Bierkens, M.F.P. - \ 2013
Water Resources Research 49 (2013)8. - ISSN 0043-1397 - p. 4687 - 4699.
united-states - hydrological model - water-resources - climate-change - discharge - predictability - availability - prediction - validation - balances
We investigate the relative contributions of initial conditions (ICs) and meteorological forcing (MF) to the skill of the global seasonal streamflow forecasting system FEWS-World, using the global hydrological model PCRaster Global Water Balance. Potential improvement in forecasting skill through better climate prediction or by better estimation of ICs through data assimilation depends on the relative importance of these sources of uncertainty. We use the Ensemble Streamflow Prediction (ESP) and reverse ESP (revESP) procedure to explore the impact of both sources of uncertainty at 78 stations on large global basins for lead times upto 6 months. We compare the ESP and revESP forecast ensembles with retrospective model simulations driven by meteorological observations. For each location, we determine the critical lead time after which the importance of ICs is surpassed by that of MF. We analyze these results in the context of prevailing hydroclimatic conditions for larger basins. This analysis suggests that in some basins forecast skill may be improved by better estimation of initial hydrologic states through data assimilation; whereas in others skill improvement depends on better climate prediction. For arctic and snowfed rivers, forecasts of high flows may benefit from assimilation of snow and ice data. In some snowfed basins where the onset of melting is highly sensitive to temperature changes, forecast skill depends on better climate prediction. In monsoonal basins, the variability of the monsoon dominates forecasting skill, except for those where snow and ice contribute to streamflow. In large basins, initial surface water and groundwater states are important sources of skill.
Making Sense of Agrobiodiversity, Diet, and Intensification of Smallholder Family Farming in the Highland Andes of Ecuador
Oyarzun, P.J. ; Borja, R.M. ; Sherwood, S. ; Parra, V. - \ 2013
Ecology of Food and Nutrition 52 (2013)6. - ISSN 0367-0244 - p. 515 - 541.
nutrition - biodiversity - food - agriculture - validation - diversity - stability - recall - health - crops
Methods are needed for helping researchers and farmers to interactively describe and analyze local practices in search of opportunities for improving health, environment, and economy. The authors worked with smallholder family farmers in five Andean villages in Ecuador to apply participatory four-cell analysis (PFCA) in characterizing agrobiodiversity. Margelef and Shannon indices examined ecological richness and evenness, and a simplified 24-hour dietary recall characterized food consumption. Cross-analysis tested interactions among agrobiodiversity, farm size, and diet. Overall trends appeared to work against sustainable intensification, with notable heterogeneity and positive deviance found in the practices of relatively smaller enterprises, representing a potential resource for sustainable intensification. The suite of methods was determined useful for initiating researcher-farmer explorations of promising innovation pathways.
Factors influencing assessment quality in higher vocational education
Baartman, L. ; Gulikers, J.T.M. ; Dijkstra, A. - \ 2013
Assessment & Evaluation in Higher Education 38 (2013)8. - ISSN 0260-2938 - p. 978 - 997.
assessing professional competence - argument-based approach - validity - validation - performance
The development of assessments that are fit to assess professional competence in higher vocational education requires a reconsideration of assessment methods, quality criteria and (self)evaluation. This article examines the self-evaluations of nine courses of a large higher vocational education institute. Per course, 4–11 teachers and 3–10 students participated. The purpose of this article is to critically examine the quality of assessment in higher vocational education, to identify critical factors influencing assessment quality and to study whether self-evaluation leads to concrete points for improvement. Results show that strong points are fitness for purpose, comparability and fairness. Weak points are reproducibility of decisions and development of self-regulated learning. Critical factors are the translation of competences into assessment criteria to be used in daily lessons and the involvement of the work field. The self-evaluations generated many points for improvement, but not all were translated into actions. Altogether, this article provides a rich picture of assessment quality in higher education and identifies quality aspects that need improvement, (partly) confirming other research on current assessment methods.
Application of gas chromatography–(triple quadrupole) massspectrometry with atmospheric pressure chemical ionization for thedetermination of multiclass pesticides in fruits and vegetables
Cherta, L. ; Portoles, T. ; Beltran, J. ; Pitarch, E. ; Mol, J.G.J. ; Hernandez, F. - \ 2013
Journal of Chromatography. A, Including electrophoresis and other separation methods 1314 (2013). - ISSN 0021-9673 - p. 224 - 240.
solid-phase extraction - residue analysis - multiresidue method - organic pollutants - quechers method - gc-ms - validation - ms/ms - water
A multi-residue method for the determination of 142 pesticide residues in fruits and vegetables has been developed using a new atmospheric pressure chemical ionization (APCI) source for coupling gas chromatography (GC) to tandem mass spectrometry (MS). Selected reaction monitoring (SRM) mode has been applied, acquiring three transitions for each compound. In contrast to the extensive fragmentation typically obtained in classical electron ionization (EI), the soft APCI ionization allowed the selection of highly abundant protonated molecules ([M+H](+)) as precursor ions for most compounds. This was favorable for both sensitivity and selectivity. Validation of the method was performed in which both quantitative and qualitative parameters were assessed using orange, tomato and carrot samples spiked at two levels, 0.01 and 0.1mg/kg. The QuEChERS method was used for sample preparation, followed by a 10-fold dilution of the final acetonitrile extract with a mixture of hexane and acetone. Recovery and precision were satisfactory in the three matrices, at both concentration levels. Very low limits of detection (down 0.01µg/kg for the most sensitive compounds) were achieved. Ion ratios were consistent and identification according to EU criteria was possible in 80% (0.01mg/kg) to 96% (0.1mg/kg) of the pesticide/matrix combinations. The method was applied to the analysis of various fruits and vegetables from the Mediterranean region of Spa
Identification of drug metabolites in human plasma or serum integrating metabolite prediction, LC–HRMS and untargeted data processing.
Jacobs, P.L. ; Ridder, L.O. ; Ruijken, M. ; Rosing, H. ; Jager, N.G.L. ; Beijnen, J.H. ; Bas, R.R. ; Dongen, W.D. van - \ 2013
Bioanalysis 5 (2013)17. - ISSN 1757-6180 - p. 2115 - 2128.
ionization mass-spectrometry - preclinical safety - major metabolite - in-vivo - disposition - excretion - pharmacokinetics - inhibitor - annotation - validation
Background: Comprehensive identification of human drug metabolites in first-in-man studies is crucial to avoid delays in later stages of drug development. We developed an efficient workflow for systematic identification of human metabolites in plasma or serum that combines metabolite prediction, high-resolution accurate mass LC–MS and MS vendor independent data processing. Retrospective evaluation of predictions for 14 14C-ADME studies published in the period 2007–January 2012 indicates that on average 90% of the major metabolites in human plasma can be identified by searching for accurate masses of predicted metabolites. Furthermore, the workflow can identify unexpected metabolites in the same processing run, by differential analysis of samples of drug-dosed subjects and (placebo-dosed, pre-dose or otherwise blank) control samples. To demonstrate the utility of the workflow we applied it to identify tamoxifen metabolites in serum of a breast cancer patient treated with tamoxifen. Results & Conclusion: Previously published metabolites were confirmed in this study and additional metabolites were identified, two of which are discussed to illustrate the advantages of the workflow.
Sensitivity analysis and calibration of the Modified Universal Soil Loss Equation (MUSLE) for the upper Malewa Catchment, Kenya
Odongo, V.O. ; Onyando, J.O. ; Mutua, B.M. ; Oel, P.R. van; Becht, R. - \ 2013
International Journal of Sediment Research 28 (2013)3. - ISSN 1001-6279 - p. 368 - 383.
sediment rating curves - uncertainty analysis - hydrologic-models - river catchment - erosion - yield - delivery - runoff - validation - greece
Simulation models are widely used for studying physical processes such as surface runoff, sediment transport and sediment yield in catchments. Most models need case-specific empirical data for parameterization before being applied especially in regions other than the ones they have been developed. Sensitivity analysis is usually performed to determine the most influential factors of a model so that they can be prioritized for optimization. In this way uncertainties in model outputs can be reduced considerably. This study evaluates the commonly used modified universal soil loss equation (MUSLE) model used for sediment yield simulation for the case of the upper Malewa catchment in Kenya. The conceptual factors of the model are assessed relative to the hydrological factors in the model. Also, the sensitivity of the model to the choice of the objective function in calibration is tested. The Sobol' sensitivity analysis method was used for evaluating the degree of sensitivity of the conceptual and hydrological factors for sediment yield simulations using the MUSLE model. Nash-Sutcliffe Efficiency (NSE) and the modified Nash-Sutcliffe Efficiency (NSEm) are used to test the sensitivity of the model to the choice of the objective function and robustness of model performance with sediment data measured from upper Malewa catchment, Kenya. The results indicate that the conceptual factors are the most sensitive factors of the MUSLE model contributing about 66% of the variability in the output sediment yield. Increased variability of sediment yield output was also observed. This was attributed to interactions of input factors. For the upper Malewa catchment calibration of the MUSLE model indicates that the use of NSEm as an objective function provides stable results, which indicates that the model can satisfactorily be applied for sediment yield simulations.
Receptor-based high-throughput screening and identification of estrogens in dietary supplements using bioaffinity liquid-chromatography ion mobility mass spectrometry
Aqai, P. ; Gómez Blesa, N. ; Major, H. ; Pedotti, P. ; Varani, L. ; Ferrero, V.E.V. ; Haasnoot, W. ; Nielen, M.W.F. - \ 2013
Analytical and Bioanalytical Chemistry 405 (2013)29. - ISSN 1618-2642 - p. 9427 - 9436.
ms-binding assays - multi-residue method - anabolic-steroids - lc-ms - nutritional supplements - chemical derivatization - native marker - contamination - transporter - validation
A high-throughput bioaffinity liquid chromatography-mass spectrometry (BioMS) approach was developed and applied for the screening and identification of recombinant human estrogen receptor a (ERa) ligands in dietary supplements. For screening, a semi-automated mass spectrometric ligand binding assay was developed applying 13C2,15¿N-tamoxifen as non-radioactive label and fast ultra-high-performance–liquid chromatography–electrospray ionisation–triple-quadrupole-MS (UPLC-QqQ-MS), operated in the single reaction monitoring mode, as a readout system. Binding of the label to ERa-coated paramagnetic microbeads was inhibited by competing estrogens in the sample extract yielding decreased levels of the label in UPLC-QqQ-MS. The label showed high ionisation efficiency in positive electrospray ionisation (ESI) mode, so the developed BioMS approach is able to screen for estrogens in dietary supplements despite their poor ionisation efficiency in both positive and negative ESI modes. The assay was performed in a 96-well plate, and all these wells could be measured within 3 h. Estrogens in suspect extracts were identified by full-scan accurate mass and collision-cross section (CCS) values from a UPLC-ion mobility-Q-time-of-flight-MS (UPLC-IM-Q-ToF-MS) equipped with a novel atmospheric pressure ionisation source. Thanks to the novel ion source, this instrument provided picogram sensitivity for estrogens in the negative ion mode and an additional identification point (experimental CCS values) next to retention time, accurate mass and tandem mass spectrometry data. The developed combination of bioaffinity screening with UPLC-QqQ-MS and identification with UPLC-IM-Q-ToF-MS provides an extremely powerful analytical tool for early warning of ERa bioactive compounds in dietary supplements as demonstrated by analysis of selected dietary supplements in which different estrogens were identified.
Evaluation of food and nutrient intake assessment using concentration biomarkers in European adolescents from the Healthy Lifestyle in Europe by Nutrition in Adolescence study
Vandevijvere, S. ; Geelen, A. ; Gonzalez-Gross, M. ; Veer, P. van 't; Dallongeville, J. ; Mouratidu, T. ; Dekkers, A. ; Börnhorst, C. ; Breidenassel, C. - \ 2013
The British journal of nutrition 109 (2013)4. - ISSN 0007-1145 - p. 736 - 747.
serum cholesteryl esters - n-3 fatty-acids - dietary-intake - energy-intake - additional measurements - micronutrient intake - biochemical markers - adipose-tissue - vitamin-c - validation
Accurate food and nutrient intake assessment is essential for investigating diet–disease relationships. In the present study, food and nutrient intake assessment among European adolescents using 24 h recalls (mean of two recalls) and a FFQ (separately and the combination of both) were evaluated using concentration biomarkers. Biomarkers included were vitamin C, ß-carotene, DHA+EPA, vitamin B12 (cobalamin and holo-transcobalamin) and folate (erythrocyte folate and plasma folate). For the evaluation of the food intake assessment 390 adolescents were included, while 697 were included for the nutrient intake assessment evaluation. Spearman rank and Pearson correlations, and validity coefficients, which are correlations between intake estimated and habitual true intake, were calculated. Correlations were higher between frequency of food consumption (from the FFQ) and concentration biomarkers than between mean food intake (from the recalls) and concentration biomarkers, especially for DHA+EPA (r 0·35 v. r 0·27). Most correlations were higher among girls than boys. For boys, the highest validity coefficients were found for frequency of fruit consumption (0·88) and for DHA+EPA biomarker (0·71). In girls, the highest validity coefficients were found for fruit consumption frequency (0·76), vegetable consumption frequency (0·74), mean fruit intake (0·90) and DHA+EPA biomarker (0·69). After exclusion of underreporters, correlations slightly improved. Correlations between usual food intakes, adjusted for food consumption frequency, and concentration biomarkers were higher than correlations between mean food intakes and concentration biomarkers. In conclusion, two non-consecutive 24 h recalls in combination with a FFQ seem to be appropriate to rank subjects according to their usual food intake
Practical Experiences with an Extended Screening Strategy for Genetically Modified Organisms (GMOs) in Real-Life Samples
Scholtens-Toma, I.M.J. ; Laurensse, E. ; Molenaar, B. ; Zaaijer, S. ; Gaballo, H.M.S. ; Boleij, P.A. ; Bak, A. ; Kok, E.J. - \ 2013
Journal of Agricultural and Food Chemistry 61 (2013)38. - ISSN 0021-8561 - p. 9097 - 9109.
modified maize - reference molecules - quantitation - validation
Nowadays most animal feed products imported into Europe have a GMO (genetically modified organism) label. This means that they contain European Union (EU)-authorized GMOs. For enforcement of these labeling requirements, it is necessary, with the rising number of EU-authorized GMOs, to perform an increasing number of analyses. In addition to this, it is necessary to test products for the potential presence of EU-unauthorized GMOs. Analysis for EU-authorized and -unauthorized GMOs in animal feed has thus become laborious and expensive. Initial screening steps may reduce the number of GMO identification methods that need to be applied, but with the increasing diversity also screening with GMO elements has become more complex. For the present study, the application of an informative detailed 24-element screening and subsequent identification strategy was applied in 50 animal feed samples. Almost all feed samples were labeled as containing GMO-derived materials. The main goal of the study was therefore to investigate if a detailed screening strategy would reduce the number of subsequent identification analyses. An additional goal was to test the samples in this way for the potential presence of EU-unauthorized GMOs. Finally, to test the robustness of the approach, eight of the samples were tested in a concise interlaboratory study. No significant differences were found between the results of the two laboratories.
Measuring fast-temporal sediment fluxes with an analogue acoustic sensor: a wind tunnel study
Poortinga, A. ; Minnen, J. van; Keijsers, J.G.S. ; Riksen, M.J.P.M. ; Goossens, D. ; Seeger, K.M. - \ 2013
PLoS ONE 8 (2013)9. - ISSN 1932-6203
eolische processen - sediment - windtunnels - meettechnieken - aeolian processes - sediment - wind tunnels - measurement techniques - inland drift-sand - aeolian transport - erosion - velocity - cloud - soil - validation - efficiency - intensity - saltation
In aeolian research, field measurements are important for studying complex wind-driven processes for land management evaluation and model validation. Consequently, there have been many devices developed, tested, and applied to investigate a range of aeolian-based phenomena. However, determining the most effective application and data analysis techniques is widely debated in the literature. Here we investigate the effectiveness of two different sediment traps (the BEST trap and the MWAC catcher) in measuring vertical sediment flux. The study was performed in a wind tunnel with sediment fluxes characterized using saltiphones. Contrary to most studies, we used the analogue output of five saltiphones mounted on top of each other to determine the total kinetic energy, which was then used to calculate aeolian sediment budgets. Absolute sediment losses during the experiments were determined using a balance located beneath the test tray. Test runs were conducted with different sand sizes and at different wind speeds. The efficiency of the two traps did not vary with the wind speed or sediment size but was affected by both the experimental setup (position of the lowest trap above the surface and number of traps in the saltation layer) and the technique used to calculate the sediment flux. Despite this, good agreement was found between sediment losses calculated from the saltiphone and those measured using the balance. The results of this study provide a framework for measuring sediment fluxes at small time resolution (seconds to milliseconds) in the field.
In aeolian research, field measurements are important for studying complex wind-driven processes for land management evaluation and model validation. Consequently, there have been many devices developed, tested, and applied to investigate a range of aeolian-based phenomena. However, determining the most effective application and data analysis techniques is widely debated in the literature. Here we investigate the effectiveness of two different sediment traps (the BEST trap and the MWAC catcher) in measuring vertical sediment flux. The study was performed in a wind tunnel with sediment fluxes characterized using saltiphones. Contrary to most studies, we used the analogue output of five saltiphones mounted on top of each other to determine the total kinetic energy, which was then used to calculate aeolian sediment budgets. Absolute sediment losses during the experiments were determined using a balance located beneath the test tray. Test runs were conducted with different sand sizes and at different wind speeds. The efficiency of the two traps did not vary with the wind speed or sediment size but was affected by both the experimental setup (position of the lowest trap above the surface and number of traps in the saltation layer) and the technique used to calculate the sediment flux. Despite this, good agreement was found between sediment losses calculated from the saltiphone and those measured using the balance. The results of this study provide a framework for measuring sediment fluxes at small time resolution (seconds to milliseconds) in the field.
An evaluation of WRF's ability to reproduce the surface wind over complex terrain based on typical circulation patterns.
Jiménez, P.A. ; Dudhia, J. ; González-Rouco, J.F. ; Montávez, J.P. ; Garcia-Bustamante, E. ; Navarro, J. ; Vilà-Guerau de Arellano, J. ; Munoz-Roldán, A. - \ 2013
Journal of Geophysical Research: Atmospheres 118 (2013)14. - ISSN 2169-897X - p. 7651 - 7669.
regional climate model - cluster-analysis - quality-assurance - mesoscale model - united-states - variability - validation - reanalysis - classification - simulation
 The performance of the Weather Research and Forecasting (WRF) model to reproduce the surface wind circulations over complex terrain is examined. The atmospheric evolution is simulated using two versions of the WRF model during an over 13¿year period (1992 to 2005) over a complex terrain region located in the northeast of the Iberian Peninsula. A high horizontal resolution of 2km is used to provide an accurate representation of the terrain features. The multiyear evaluation focuses on the analysis of the accuracy displayed by the WRF simulations to reproduce the wind field of the six typical wind patterns (WPs) identified over the area in a previous observational work. Each pattern contains a high number of days which allows one to reach solid conclusions regarding the model performance. The accuracy of the simulations to reproduce the wind field under representative synoptic situations, or pressure patterns (PPs), of the Iberian Peninsula is also inspected in order to diagnose errors as a function of the large-scale situation. The evaluation is accomplished using daily averages in order to inspect the ability of WRF to reproduce the surface flow as a result of the interaction between the synoptic scale and the regional topography. Results indicate that model errors can originate from problems in the initial and lateral boundary conditions, misrepresentations at the synoptic scale, or the realism of the topographic features.
Lipids from yeasts and fungi: Tomorrow's source of Biodiesel?
Meeuwse, P. ; Sanders, J.P.M. ; Tramper, J. ; Rinzema, A. - \ 2013
Biofuels Bioproducts and Biorefining 7 (2013)5. - ISSN 1932-104X - p. 512 - 524.
solid-state fermentation - fatty-acid production - gamma-linolenic acid - sugar-beet pulp - mortierella-isabellina - oleaginous fungi - chemostat model - scale-up - validation - cultures
In the search for new transport fuels from renewable resources, biodiesel from microbial lipids comes into view. We have evaluated the lipid yield and energy use of a process for production of biodiesel from agricultural waste using lipid-accumulating yeast and fungi. We included different bioreactors for submerged and solid-state fermentation in our evaluation. Using existing kinetic models, we predict lipid yields on substrate between 5% and 19% (w/w), depending on the culture system. According to the same models, improvement of the yield to 25–30% (w/w) is possible, for example by genetic modifi cation of the micro-organisms. The net energy ratio of the non-optimized systems varies between 0.8 and 2.5 MJ produced per MJ used; energy use for pre-treatment and for oxygen transfer are most important. For the optimized systems, the net energy ratio increases to 2.9–5.5 MJ produced per MJ used, which can compete very well with other biofuels such as bioethanol or algal biodiesel. This shows that, although quite some work still has to be done, microbial lipids have the potential to be tomorrow’s source of biodiesel. © 2013 Society of Chemical Industry and John Wiley & Sons, Ltd
Assessing spatial uncertainties of land allocation using a scenario approach and sensitivity analysis: A study for land use in Europe
Verburg, P.H. ; Tabeau, A.A. ; Hatna, E. - \ 2013
Journal of Environmental Management 127 (2013)suppl.. - ISSN 0301-4797 - p. S132 - S144.
climate-change - global change - cover data - future - models - projections - validation - impact - eu
Land change model outcomes are vulnerable to multiple types of uncertainty, including uncertainty in input data, structural uncertainties in the model and uncertainties in model parameters. In coupled model systems the uncertainties propagate between the models. This paper assesses uncertainty of changes in future spatial allocation of agricultural land in Europe as they arise from a general equilibrium model coupled to a spatial land use allocation model. Two contrasting scenarios are used to capture some of the uncertainty in the development of typical combinations of economic, demographic and policy variables. The scenario storylines include different measurable assumptions concerning scenario specific drivers (variables) and parameters. Many of these assumptions are estimations and thus include a certain level of uncertainty regarding their true values. This leads to uncertainty within the scenario outcomes. In this study we have explored how uncertainty in national-level assumptions within the contrasting scenario assumptions translates into uncertainty in the location of changes in agricultural land use in Europe. The results indicate that uncertainty in coarse-scale assumptions does not translate into a homogeneous spread of the uncertainty within Europe. Some regions are more certain than others in facing specific land change trajectories irrespective of the uncertainty in the macro-level assumptions. The spatial spread of certain and more uncertain locations of land change is dependent on location conditions as well as on the overall scenario conditions. Translating macro-level uncertainties to uncertainties in spatial patterns of land change makes it possible to better understand and visualize the land change consequences of uncertainties in model input variables.
Selected Reaction Monitoring method to determine the species origin of blood-based binding agents in meats: a collaborative study
Grundy, H. ; Read, W.A. ; Macarthur, R. ; Alewijn, M. - \ 2013
Food Chemistry 141 (2013)4. - ISSN 0308-8146 - p. 3531 - 3536.
quadrupole mass-spectrometry - liquid-chromatography - products - validation
Binding products or food ‘glues’ are used throughout the food industry to increase the meat use rate or to augment economic efficiency. Some of these binders contain thrombin from bovine and porcine blood. The European parliament has recently banned thrombin-based additives and labelling legislation governs their use in the US. A mass spectrometry screening method is available to detect the addition of thrombin agents to foods as there is a need to protect consumers and to avoid misleading trade practices. We report the details of an inter-laboratory trial to determine the transferability of this method to operators in various food testing laboratories, each using a different triple quadrupole mass spectrometer design. The trial was successful with the species origin of the binding agent contained in each of the forty three test materials being correctly reported by the participants. This is consistent with a false positive and false negative rate of zero percent. This is the first collaborative study, as far as we are aware, which involves a liquid chromatography mass spectrometry (LC-MS/MS) application to approach a food authenticity issue.
Relative validity of the food frequency questionnaire used to assess dietary intake in the Leiden Longevity Study
Streppel, M.T. ; Vries, J.H.M. de; Meyboom, S. ; Beekman, M. ; Craen, A.J.M. ; Slagboom, P.E. ; Feskens, E.J.M. - \ 2013
Nutrition Journal 12 (2013). - ISSN 1475-2891 - 8 p.
basal metabolic-rate - energy-intake - goldberg cutoff - limitations - validation - markers - design
Background - Invalid information on dietary intake may lead to false diet-disease associations. This study was conducted to examine the relative validity of the food frequency questionnaire (FFQ) used to assess dietary intake in the Leiden Longevity Study. Methods - A total of 128 men and women participating in the Leiden Longevity Study were included in the present validation study. The performance of the FFQ was evaluated using the mean of three 24-hour recalls as the reference method. Evaluation in estimating dietary intake at the group level was done by paired t-tests. The relative validity of the individual energy adjusted level of intake was assessed with correlation analyses (Pearson’s), with correction for measurement error. Results - On group level, the FFQ overestimated as well as underestimated absolute intake of various nutrients and foods. The Bland and Altman plot for total energy intake showed that the agreement between the FFQ and the 24-hour recalls was dependent of intake level. Pearson correlation coefficients ranged from 0.21 (alpha linolenic acid) to 0.78 (ethanol) for nutrients and from -0.02 (legumes, non-significant) to 0.78 (alcoholic beverages) for foods. Adjustment for energy intake slightly lowered the correlation coefficients for nutrients (mean coefficient: 0.48 versus 0.50), while adjustment for within-subject variation in the 24-h recalls resulted in higher correlation coefficients for both nutrients and foods (mean coefficient: 0.69 for nutrients and 0.65 for foods). Conclusions - For most nutrients and foods, the ability of the FFQ to rank subjects was acceptable to good.
Comparison of satellite-derived land surface temperature and air temperature from meteorological stations on the Pan-Arctic scale
Urban, M. ; Eberle, J. ; Hüttich, C. ; Schmullius, C. ; Herold, M. - \ 2013
Remote Sensing 5 (2013)5. - ISSN 2072-4292 - p. 2348 - 2367.
recent climate-change - modis products - orbital drift - data set - avhrr - emissivity - dynamics - models - lst - validation
Satellite-based temperature measurements are an important indicator for global climate change studies over large areas. Records from Moderate Resolution Imaging Spectroradiometer (MODIS), Advanced Very High Resolution Radiometer (AVHRR) and (Advanced) Along Track Scanning Radiometer ((A)ATSR) are providing long-term time series information. Assessing the quality of remote sensing-based temperature measurements provides feedback to the climate modeling community and other users by identifying agreements and discrepancies when compared to temperature records from meteorological stations. This paper presents a comparison of state-of-the-art remote sensing-based land surface temperature data with air temperature measurements from meteorological stations on a pan-arctic scale (north of 60° latitude). Within this study, we compared land surface temperature products from (A)ATSR, MODIS and AVHRR with an in situ air temperature (Tair) database provided by the National Climate Data Center (NCDC). Despite analyzing the whole acquisition time period of each land surface temperature product, we focused on the inter-annual variability comparing land surface temperature (LST) and air temperature for the overlapping time period of the remote sensing data (2000–2005). In addition, land cover information was included in the evaluation approach by using GLC2000. MODIS has been identified as having the highest agreement in comparison to air temperature records. The time series of (A)ATSR is highly variable, whereas inconsistencies in land surface temperature data from AVHRR have been found.
The costs of complex model optimization
Rubingh, C.M. ; Martens, H. ; Voet, H. van der; Smilde, A.K. - \ 2013
Chemometrics and Intelligent Laboratory Systems 125 (2013). - ISSN 0169-7439 - p. 139 - 146.
partial least-squares - metabolomics data - validation - selection - freedom
Each data-driven action in data modelling consumes degrees of freedom, whether it concerns estimation of parameters, estimation of meta-parameters or selecting variables. By using a double cross validation approach for degrees of freedom calculation the costs for meta-parameter estimation and variable selection can be determined explicitly. The only assumptions are independent and identically distributed errors, which make the approach applicable to many predictive modelling techniques
Development of an immunochromatographic assay based on carbon nanoparticles for the determination of the phytoregulator forchlorfenuron
Suaréz-Pantaleón, C. ; Wichers, J.H. ; Abad-Somovilla, A. ; Amerongen, A. van - \ 2013
Biosensors and Bioelectronics 42 (2013). - ISSN 0956-5663 - p. 170 - 176.
lateral flow immunoassay - antibody-based immunoassay - computer image-analysis - rapid detection - sensitive detection - dipstick assay - water samples - strip test - validation - biosensor
Rapid analytical methods enabling the determination of diverse targets are essential in a number of research areas, from clinical diagnostics to feed and food quality and safety. Herein, the development of a quantitative immunochromatographic assay for the detection of the synthetic phytoregulator forchlorfenuron (CPPU) is described. The competitive lateral flow immunoassay (LFIA) was based on the immobilization onto a nitrocellulose membrane of an ovalbumin–CPPU conjugate (test line) and on the use of an immunodetection ligand consisting of carbon nanoparticles labeled with an anti-CPPU monoclonal antibody through interaction with a secondary antibody. The presence of CPPU in horticultural samples was visually interpreted by the decrease in the black signal intensity of the test line, according to the competitive character of the format. The quantitative determination of the analyte was easily performed by a two-step procedure consisting of flatbed scanning of the strips followed by computer-based image analysis of the pixel gray volumes of the test lines. Under optimized conditions, the immunochromatographic test afforded a limit of quantification in buffer of 89 ng/L. The accuracy of the strip test was assessed by the analysis of fruit samples with incurred residues, and the obtained results were compared with those derived from two reference methods, ELISA and HPLC. The LOQ of the CPPU-specific LFIA in kiwifruits and grapes was established at 33.4 µg/kg. The excellent analytical performance of the developed strip test demonstrates the potential of immunochromatographic assays for the quantitative monitoring of small organic molecules in complex matrices.
Sensitivity and uncertainty of analytical footprint models according to a combined natural tracer and ensemble approach
Boer, A. van de; Moene, A.F. ; Schüttemeyer, D. ; Graf, A. - \ 2013
Agricultural and Forest Meteorology 169 (2013). - ISSN 0168-1923 - p. 1 - 11.
flux measurements - sonic anemometer - carbon-dioxide - surface-layer - water-vapor - exchange - heat - validation - efflux - fetch
Evaluations of analytical footprint models using data from several stations located in different land use types are still scarce, but valuable for defining the spatial context of the measurements. Therefore, we evaluated two analytical footprint models by applying a ‘forward’ and an ‘inversion’ method. We used eddy covariance measurements from a flat agricultural landscape in western Germany in the summer of 2009, with seven eddy covariance systems over three different land use types with contrasting sensible heat fluxes. We found that the model of Hsieh et al. (2000. Adv. Water Resour. 23, 765–772) and of Kormann and Meixner (2001. Boundary Layer Meteorol. 99, 207–224) are both overestimating the distance of the peak contribution of the footprint. In our evaluation, the former model performs slightly better, independent of whether the crosswind dispersion was used from the latter model, or from the proposed model by Detto et al. (2006. Water Resour. Res. 42, 1–16).
European ring trial to evaluate ELISAs for the diagnosis of infection with Rift Valley fever virus
Kortekaas, J.A. ; Kant, J. ; Vloet, R.P.M. ; Cêtre-Sossah, C. ; Marianneau, P. ; Lacote, S. ; Banyard, A.C. ; Jeffries, C. ; Eiden, M. ; Groschup, M. ; Jäckel, S. ; Hevia, E. ; Brun, A. - \ 2013
Journal of Virological Methods 187 (2013)1. - ISSN 0166-0934 - p. 177 - 181.
linked-immunosorbent-assay - reverse transcription-pcr - nucleocapsid protein - domestic ruminants - capture elisa - igg antibody - validation - sandwich - humans - sheep
A ring trial was organized to evaluate Rift Valley fever virus (RVFV) ELISAs by European laboratories. A total of five ELISAs, two of which specific for IgM antibodies, were evaluated by six participants. Sera were derived from cattle or sheep and originated from either a RVFV endemic area, a RVFV-free area or from experimental infection studies. Cohen's kappa analysis showed higher than 90% agreement of two commercially available ELISAs with the virus neutralization test, suggesting that primary screening as well as serological confirmation using these ELISAs is feasible. More extensive validations with sera of known IgM status are, however, required to determine agreement between IgM ELISAs.
Evaluation of the variation in semantic contents of class sets on modelling dynamics of land-use changes
Jansen, L.J.M. ; Veldkamp, T.A. - \ 2012
International Journal of Geographical Information Science 26 (2012)4. - ISSN 1365-8816 - p. 717 - 746.
use change scenarios - central-america - igbp discover - multiscale - population - database - environment - validation - accuracy - patterns
Understanding the scale of interaction and the scale of different environmental and social processes is of paramount importance to define and explain the interaction of human-environment systems. There are three dimensions of scale: space, time and the organisational hierarchy as constructed by the observer. The latter is synonymous with the variation in semantic contents of data expressed as differences in categorisation. This dimension of scale has received little attention. In this article the relationship between the semantic contents of data and modelling dynamics is explored using two land-cover data sets for Romania, one based on the Land-Cover Classification System and the other as used in the EURURALIS study. Three levels of semantic contents of the LCCS data and the single semantic level present in the EURURALIS data are used to establish empirical relations between the land-cover class and its explaining factors. The analysis results show that the variations in semantic contents of data within one data set and between two data sets lead to different sets of spatial determinants for land cover. We did not recognise patterns when establishing the organisational hierarchy. Future policy and decision-making depend to a great extent on which organisational hierarchy is present in the data set used to formulate a policy or to make an informed decision. This would mean that if the same results would be found in other data sets using different models not only multi-scale but also multi-semantic analysis are needed in order to make meaningful predictions of spatially explicit land change.
Comparing optimized CO emission estimates using MOPITT or NOAA surface network observations
Hooghiemstra, P.B. ; Krol, M.C. ; Bergamaschi, P. ; Laat, A.T.J. de; Werf, G.R. van der; Novelli, P.C. ; Deeter, M.N. ; Aben, I. ; Rockmann, T. - \ 2012
Journal of Geophysical Research: Atmospheres 117 (2012). - ISSN 2169-897X - 23 p.
variational data assimilation - zoom model tm5 - carbon-monoxide - tropospheric chemistry - inversion - validation - sciamachy - algorithm - pollution - aircraft
This paper compares two global inversions to estimate carbon monoxide (CO) emissions for 2004. Either surface flask observations from the National Oceanic and Atmospheric Administration Earth System Research Laboratory (NOAA/ESRL) Global Monitoring Division (GMD) or CO total columns from the Measurement of Pollution in the Troposphere (MOPITT) instrument are assimilated in a 4D-Var framework. Inferred emission estimates from the two inversions are consistent over the Northern Hemisphere (NH). For example, both inversions increase anthropogenic CO emissions over Europe (from 46 to 94 Tg CO/yr) and Asia (from 222 to 420 Tg CO/yr). In the Southern Hemisphere (SH), three important findings are reported. First, due to their different vertical sensitivity, the stations-only inversion increases SH biomass burning emissions by 108 Tg CO/yr more than the MOPITT-only inversion. Conversely, the MOPITT-only inversion results in SH natural emissions (mainly CO from oxidation of NMVOCs) that are 185 Tg CO/yr higher compared to the stations-only inversion. Second, MOPITT-only derived biomass burning emissions are reduced with respect to the prior which is in contrast to previous (inverse) modeling studies. Finally, MOPITT derived total emissions are significantly higher for South America and Africa compared to the stations-only inversion. This is likely due to a positive bias in the MOPITT V4 product. This bias is also apparent from validation with surface stations and ground-truth FTIR columns. Our results show that a combined inversion is promising in the NH. However, implementation of a satellite bias correction scheme is essential to combine both observational data sets in the SH.
A land-use systems approach to represent land-use dynamics at continental and global scales
Letourneau, A.P. ; Verburg, P.H. ; Stehfest, E. - \ 2012
Environmental Modelling & Software 33 (2012). - ISSN 1364-8152 - p. 61 - 79.
remotely-sensed data - cover change - agricultural land - costa-rica - model - validation - science - forest - sustainability - biodiversity
Most of the current global land cover datasets and global scale land-use models use a classification of land cover based on the dominant land cover type within a distinct region or pixel. Such a classification disregards the diversity and intensity of human influence on land systems. In this paper we propose a novel way of classification and modeling land-use using a classification based on land-use systems (LUSs) that represent specific combinations of human-environment interactions. A cluster analysis was used to identify and map these LUSs. The analysis accounted for population density, accessibility to market places, land-use/cover types and livestock densities. A conceptual framework was developed to model dynamics in LUSs accounting for both land cover and land management changes. LUSs changes were simulated based on changes in both local socio-economic and biophysical conditions and regional-scale changes in demand for agricultural products. The new land-use systems change model was used in the context of the integrated assessment model IMAGE.
Assessment of performance of selected serological tests for diagnosing brucellosis in pigs.
Munoz, P.M. ; Blasco, J.M. ; Engel, B. ; Miguel, M.J. de; Marín, C.M. ; Dieste, L. ; Mainar-Jaime, R.C. - \ 2012
Veterinary Immunology and Immunopathology 146 (2012). - ISSN 0165-2427 - p. 150 - 158.
fluorescence polarization assay - melitensis infection - swine brucellosis - validation - suis - specificity - sensitivity - dependence - antigens - efficacy
Swine brucellosis due to Brucella suis is considered an emerging zoonotic disease whose control is based on serological testing and the subsequent culling of seropositive animals or the full depopulation of affected flocks. Here we assessed the performance of several serological tests (Rose Bengal Test [RBT], indirect ELISA [i-ELISA], blocking ELISA [b-ELISA], and two competitive ELISAs [c-ELISA]) for diagnosing swine brucellosis caused by B. suis biovar 2. Both frequentistic and Bayesian statistical inference were used. A frequentistic analysis, using sera from known gold standard (GS) populations (i.e., from truly infected or brucellosis free animals), resulted in maximum (100%) diagnostic sensitivity (Se) and specificity (Sp) in the RBT, i-ELISA and b-ELISA tests. However, c-ELISAs resulted in lower diagnostic Se (ranging from 68.5% to 92.6%, according to the different cut-offs selected). A Bayesian analysis of tests yielding the best diagnostic performance with GS sera (RBT, i-ELISA and b-ELISA), but using a large collection of field sera, resulted in similar Se among tests but markedly lower (˜80%) than that resulting from the frequentistic analysis using the GS serum populations. By contrast, the estimated Sp in the Bayesian analysis was only slightly lower than 100%, thus similar to that obtained frequentistically. Our results show that adequate diagnostic tests for brucellosis in swine are available, but also emphasize the need for more extensive validation studies before applying these tests under field conditions.
Estimating total suspended matter concentration in tropical waters of the Berau estuary, Indonesia
Ambarwulan, W. ; Verhoef, W. ; Mannaerts, C.M. ; Salama, M.S. - \ 2012
International Journal of Remote Sensing 33 (2012)16. - ISSN 0143-1161 - p. 4919 - 4936.
ocean color - atmospheric correction - meris measurements - baltic sea - products - validation - algorithm - simulation - retrieval - skagerrak
This study presents the application of a semi-empirical approach, based on the Kubelka–Munk (K-M) model, to retrieve the total suspended matter (TSM) concentration of water bodies from ocean colour remote sensing. This approach is validated with in situ data sets compiled from the tropical waters of Berau estuary, Indonesia. Compared to a purely empirical approach, the K-M model provides better results in the retrieval of TSM concentration on both data sets (in situ and Medium Resolution Imaging Spectrometer (MERIS)). In this study, the K-M model was calibrated with in situ measurements of remote-sensing reflectance (R rs) and TSM concentration. Next, the inverse K-M model was successfully applied to images taken by the MERIS instrument by generating regional maps of TSM concentration. MERIS top-of-atmosphere radiances were atmospherically corrected using the Moderate Spectral Resolution Atmospheric Transmittance (MODTRAN) radiative transfer model. The best correlation between R rs measured in situ and R rs MERIS was found to be at a wavelength of 620 nm. The TSM concentrations retrieved using the K-M model showed a lower root mean square error (RMSE), a higher coefficient of determination and a smaller relative error than those retrieved by the purely empirical approach.
Aflatoxin determination using in-line immunoaffinity chromatopgraphy in foods
Jinap, S. ; Rijk, T.C. de; Arzandeh, S. ; Kleijnen, H.C.H. ; Zomer, P. ; Weg, G. van der; Mol, J.G.J. - \ 2012
Food Control 26 (2012)1. - ISSN 0956-7135 - p. 42 - 48.
performance liquid-chromatography - mass-spectrometry - column cleanup - trace analysis - online - validation - mycotoxins - products - nuts - contamination
Short throughput times with high precision and sensitivity are of interest of any laboratory. An in-line immunoaffinity chromatographic cleanup procedure coupled to High Performance Liquid Chromatography (HPLC) and fluorescence detection was developed for the purpose of quantification of the aflatoxin content in food (peanuts, dried figs, and paprika powder). The analysis of the aflatoxin content was performed by HPLC equipped with an in-line immunoaffinity column and a Kobra cell for enhanced detection. Detection limits ranging from 0.14 to 0.32 ng/mL and quantification limits from 0.29 to 0.64 ng/mL were obtained. The trueness was evaluated by analyzing certified reference material and through spiking of aflatoxin reference solutions to food products. The recovery ranged from 75.7 to 92.9% for AFB1, 72.1 to 103.0 % for AFB2, 76.0 to 107.9 % for AFG1 and 82.1 to 103.3% for AFG2. The intra-day (RSDr) repeatability and inter-day (RSDR) reproducibility of measurements were calculated. Both were within the maximum values obtained from the Horwitz equation. The interference experiment showed no interference from other mycotoxins.
Estimation of feed intake and digestibility in cattle consuming quality tropical roughage diets using molasses-based n-alkane boluses
Derseh, M.B. ; Pellikaan, W.F. ; Tolera, A. ; Hendriks, W.H. - \ 2012
Animal Feed Science and Technology 177 (2012)3-4. - ISSN 0377-8401 - p. 161 - 171.
dry-matter intake - herbage intake - vegetation communities - detergent fiber - sheep - markers - accuracy - pasture - validation - nutrition
A feeding experiment was conducted to measure the faecal recovery rates of n-alkanes and to evaluate molasses-based alkane boluses for feed intake and digestibility estimations in cattle consuming low-quality tropical roughages. The experiment was performed in a cross-over design with four experimental diets, four 21-day feeding runs and eight bulls. The animals received a measured amount of the experimental diets that resulted in little refusal throughout the experiment. After seven days of adaptation, the animals were dosed with molasses-based alkane boluses (each containing 200 g C32 and 150 g C36) twice daily at 07:00 and 18:00 h. Concurrent with the alkane dosing, faecal spot samples were taken twice daily until the end of each run. In addition, total faecal collections were performed over the last 5 days of each run. The mean faecal recovery rate of both natural and dosed n-alkanes ranged between 0.61 and 0.86, with the recovery showing an upward trend with increasing carbon-chain length. The recovery rate of dosed alkanes was considerably higher than that of adjacent odd-chain alkanes. Whilst diets did not differ (P=0.23) in the recovery of even-chain n-alkanes, an effect of diet (P=0.01) was observed in the recovery of odd-chain n-alkanes. The faecal concentration of dosed alkanes reached equilibrium 3.30 days into the alkane dosing. On the assumption of similar faecal recovery of adjacent n-alkanes, intake was underestimated by 12% (P
Development of a five-plex flow cytometric immunoassay for the simultaneous detection of six coccidiostats in feed and eggs
Bienenmann-Ploum, M.E. ; Huet, A.C. ; Campbell, K. ; Fodey, T.L. ; Vincent, U. ; Delahaut, P. ; Elliot, C.T. ; Nielen, M.W.F. - \ 2012
Analytical and Bioanalytical Chemistry 404 (2012)5. - ISSN 1618-2642 - p. 1361 - 1373.
time-resolved fluoroimmunoassay - veterinary drug residues - additive nicarbazin - immunosorbent-assay - tissue distribution - poultry - salinomycin - chickens - contamination - validation
Coccidiostats are the only veterinary drugs still permitted to be used as feed additives to treat poultry for coccidiosis. To protect consumers, maximum levels for their presence in food and feed have been set by the European Union (EU). To monitor these coccidiostats, a rapid and inexpensive screening method would be a useful tool. The development of such a screening method, using a flow cytometry-based immunoassay, is described. The assay uses five sets of colour-coded paramagnetic microspheres for the detection of six selected priority coccidiostats. Different coccidiostats, with and without carrier proteins, were covalently coupled onto different bead sets and tested in combination with polyclonal antisera and with a fluorescent-labelled secondary antibody. The five optimal combinations were selected for this multiplex and a simple-to-use sample extraction method was applied for screening blank and spiked eggs and feed samples. A very good correlation (r ranging from 0.995 to 0.999) was obtained with the responses obtained in two different flow cytometers (Luminex 100 and FLEXMAP 3D). The sensitivities obtained were in accordance with the levels set by the EU as the measured limits of detection for narasin/salinomycin, lasalocid, diclazuril, nicarbazin (4,4'-dinitrocarbanilide) and monensin in eggs were 0.01, 0.1, 0.5, 53 and 0.1 µg/kg and in feed 0.1, 0.2, 0.3, 9 and 1.5 µg/kg, respectively.
Genomic regions associated with bovine milk fatty acids in both summer and winter milk samples
Bouwman, A.C. ; Visker, M.H.P.W. ; Arendonk, J.A.M. van; Bovenhuis, H. - \ 2012
BMC Genetics 13 (2012). - ISSN 1471-2156 - 13 p.
wide association - genetic-parameters - dairy-cattle - bos-taurus - dgat1 - polymorphisms - replication - validation - synthase - cows
Background - In this study we perform a genome-wide association study (GWAS) for bovine milk fatty acids from summer milk samples. This study replicates a previous study where we performed a GWAS for bovine milk fatty acids based on winter milk samples from the same population. Fatty acids from summer and winter milk are genetically similar traits and we therefore compare the regions detected in summer milk to the regions previously detected in winter milk GWAS to discover regions that explain genetic variation in both summer and winter milk. Results - The GWAS of summer milk samples resulted in 51 regions associated with one or more milk fatty acids. Results are in agreement with most associations that were previously detected in a GWAS of fatty acids from winter milk samples, including eight ‘new’ regions that were not considered in the individual studies. The high correlation between the –log10(P-values) and effects of SNPs that were found significant in both GWAS imply that the effects of the SNPs were similar on winter and summer milk fatty acids. Conclusions - The GWAS of fatty acids based on summer milk samples was in agreement with most of the associations detected in the GWAS of fatty acids based on winter milk samples. Associations that were in agreement between both GWAS are more likely to be involved in fatty acid synthesis compared to regions detected in only one GWAS and are therefore worthwhile to pursue in fine-mapping studies.
Intercomparison of modis albedo retievals and in situ measurements across the global fluxnet network
Cescatti, A. ; Marcolla, B. ; Santhana Vannan, S.K. ; Roman, J.Y. ; Moors, E.J. - \ 2012
Remote Sensing of Environment 121 (2012). - ISSN 0034-4257 - p. 323 - 334.
reflectance distribution function - broad-band albedo - surface albedo - boreal forests - climate-change - vegetation - products - feedbacks - validation - instrument
Surface albedo is a key parameter in the Earth's energy balance since it affects the amount of solar radiation directly absorbed at the planet surface. Its variability in time and space can be globally retrieved through the use of remote sensing products. To evaluate and improve the quality of satellite retrievals, careful intercomparisons with in situ measurements of surface albedo are crucial. For this purpose we compared MODIS albedo retrievals with surface measurements taken at 53 FLUXNET sites that met strict conditions of land cover homogeneity. A good agreement between mean yearly values of satellite retrievals and in situ measurements was found (r2 = 0.82). The mismatch is correlated with the spatial heterogeneity of surface albedo, stressing the relevance of land cover homogeneity when comparing point to pixel data. When the seasonal patterns of MODIS albedo are considered for different plant functional types, the match with surface observations is extremely good at all forest sites. On the contrary, satellite retrievals at non-forested sites (grasslands, savannas, croplands) underestimate in situ measurements across the seasonal cycle. The mismatch observed at grassland and cropland sites is likely due to the extreme fragmentation of these landscapes, as confirmed by geostatistical attributes derived from high resolution scenes.
LaHMa: A landscape heterogeneity mapping method using hyper-temporal datasets
Bie, C.A.J.M. de; Nguyen, Thi Thu Ha ; Scarrott, R.G. ; Skidmore, A.K. - \ 2012
International Journal of Geographical Information Science 26 (2012)11. - ISSN 1365-8816 - p. 2177 - 2192.
ndvi time-series - fragmented landscapes - spatial heterogeneity - vegetation cover - avhrr - discrimination - productivity - agriculture - validation - parameters
A new quantitative method extracts a landscape heterogeneity map (LaHMa) from hyper-temporal remote-sensing data. The feature extraction method is data-driven, unbiased, and builds on the commonly used data reduction technique of Iterative Self-Organizing Data Analysis (ISODATA) clustering with the support of divergence separability indices. First, the relevant spatial-temporal variation in normalized difference vegetation index (NDVI) is classified through ISODATA clustering. Second, a series of prepared cluster maps are overlaid to examine and detect the frequency with which boundaries between clusters occur at the same location. This step identifies the boundary strength between clusters and detects spatial heterogeneity within them. Results of the method are explored for the typical agriculture-defined landscape of the Mekong delta, Vietnam, using NDVI-imagery time-series from SPOT-Vegetation and MODIS-Terra. The method extracts useful landscape heterogeneity features and can support land-cover mapping requiring information on fragmentation and land-cover gradients.
Observation uncertainty of satellite soil moisture products determined with physically-based modeling
Wanders, N. ; Karssenberg, D. ; Bierkens, M.F.P. ; Parinussa, R. ; Jeu, R. de; Dam, J.C. van; Jong, S. de - \ 2012
Remote Sensing of Environment 127 (2012). - ISSN 0034-4257 - p. 341 - 356.
passive microwave measurements - improving runoff prediction - vegetation optical depth - ers scatterometer - amsr-e - retrieval - assimilation - validation - algorithm - index
Accurate estimates of soil moisture as initial conditions to hydrological models are expected to greatly increase the accuracy of flood and drought predictions. As in-situ soil moisture observations are scarce, satellite-based estimates are a suitable alternative. The validation of remotely sensed soil moisture products is generally hampered by the difference in spatial support of in-situ observations and satellite footprints. Unsaturated zone modeling may serve as a valuable validation tool because it could bridge the gap of different spatial supports. A stochastic, distributed unsaturated zone model (SWAP) was used in which the spatial support was matched to these of the satellite soil moisture retrievals. A comparison between point observations and the SWAP model was performed to enhance understanding of the model and to assure that the SWAP model could be used with confidence for other locations in Spain. A timeseries analysis was performed to compare surface soil moisture from the SWAP model to surface soil moisture retrievals from three different microwave sensors, including AMSR-E, SMOS and ASCAT. Results suggest that temporal dynamics are best captured by AMSR-E and ASCAT resulting in an averaged correlation coefficient of 0.68 and 0.71, respectively. SMOS shows the capability of capturing the long-term trends, however on short timescales the soil moisture signal was not captured as well as by the other sensors, resulting in an averaged correlation coefficient of 0.42. Root mean square errors for the three sensors were found to be very similar (± 0.05 m3m- 3). The satellite uncertainty is spatially correlated and distinct spatial patterns are found over Spain.
Multicenter Collaborative Trial Evaluation of a Method for Detection of Human Adenoviruses in Berry Fruit
Agostino, C. D'; Cook, N. ; Bartolo, I. Di; Ruggeri, F.M. ; Berto, A. ; Martelli, F. ; Banks, M. ; Vasickova, P. ; Kralik, P. ; Pavlik, I. ; Kokkinos, P. ; Vantarakis, A. ; Söderberg, K. ; Maunula, L. ; Verhaelen, K. ; Rutjes, S. ; Roda Husman, A.M. De; Hakze-van der Honing, R.W. van der; Poel, W.H.M. van der; Kaupke, A. ; Kozyra, I. ; Rzezutka, A. ; Prodanov, J. ; Lazic, S. ; Petrovic, T. ; Carratala, A. ; Gironés, R. ; Diez-Valcarce, M. ; Hernandez, M. ; Rodriguez-Lazaro, D. - \ 2012
Food Analytical Methods 5 (2012)1. - ISSN 1936-9751 - p. 1 - 7.
pcr-based method - listeria-monocytogenes - international standard - enteric viruses - food - validation - water - contamination - environment - organisms
The qualitative performance characteristics of a qPCR-based method to detect human adenoviruses in raspberries were determined through a collaborative trial involving 11 European laboratories. The method incorporated a sample process control (murine norovirus) and an internal amplification control. Trial sensitivity or correct identification of 25-g raspberry samples artificially contaminated with between 5×102 and 5×104 PFU was 98.5%; the accordance and concordance were 97.0%. The positive predictive value was 94.2%. The trial specificity or percentage correct identification of non-artificially contaminated samples was 69.7%; the accordance was 80.0% and the concordance was 61.7%. The negative predictive value was 100%. Application of a method for the detection of human adenoviruses in food samples could be useful for routine monitoring for food safety management. It would help to determine if a route of contamination exists from human source to food supply chain which pathogenic viruses such as norovirus and hepatitis A virus could follow.
Antecedents of self identity and consequences for action control: An application of the theory of planned behaviour in the exercise domain
Bruijn, G.J. de; Verkooijen, K.T. ; Putte, B. van den; Vries, N.K. de - \ 2012
Psychology of Sports and Exercise 13 (2012)6. - ISSN 1469-0292 - p. 771 - 778.
vigorous physical-activity - continuation intentions - metaanalysis - salience - efficacy - identification - maintenance - personality - integration - validation
Objectives: To study whether exercise action control profiles should be usefully extended to include exercise identity. Further, this study investigated theory of planned behaviour antecedents of exercise identity. Design: Prospective data from 413 undergraduate students (M age ¼ 21.4; 73.5% females). Method: Validated questionnaires were used at baseline and follow-up two weeks later to assess exercise behaviour, intention, self-identity, and theory of planned behaviour concepts. Research questions were analysed using chi-square analysis, discriminant function analysis and structural equation modelling. Results were interpreted using p-values and effect sizes. Results: There was a higher proportion of exercise intenders in the strong exercise identity group than in the weak exercise identity group (81.9% vs. 14.5%) and a higher proportion of successful intenders in the high exercise identity group than in the low exercise identity group (45.5% vs. 18.2%). Affective attitude and perceived behavioural control (PBC) were the most important predictors of exercise action control. Regarding the antecedents of identity, results showed significant and small-sized associations for baseline affective attitude and perceived behavioural control and large-sized association for baseline self-identity. Conclusion: Exercise identity should be usefully employed to understand exercise motivation and action control. Affective attitude and perceived behavioural control facilitate action control and exercise identity development and are suggested to be taken into account when developing exercise interventions.
Occurrence of Fusarium Head Blight species and Fusarium mycotoxins in winter wheat in the Netherlands in 2009
Fels-Klerx, H.J. van der; Rijk, T.C. de; Booij, C.J.H. ; Goedhart, P.W. ; Boers, E.A.M. ; Zhao, C. ; Waalwijk, C. ; Mol, J.G.J. ; Lee, T.A.J. van der - \ 2012
Food Additives & Contaminants. Pt. A, Chemistry, Analysis, Control, Exposure & Risk Assessment 29 (2012)11. - ISSN 1944-0049 - p. 1716 - 1726.
small-grain cereals - deoxynivalenol - beauvericin - moniliformin - europe - maize - variability - zearalenone - validation - extraction
Most recent information on the occurrence of Fusarium Head Blight species and related mycotoxins in wheat grown in the Netherlands dates from 2001. This aim of this study was to investigate the incidence and levels of Fusarium Head Blight species and Fusarium mycotoxins, as well as their possible relationships, in winter wheat cultivated in the Netherlands in 2009. Samples were collected from individual fields of 88 commercial wheat growers. Samples were collected at harvest from 86 fields, and 2 weeks before the expected harvest date from 21 fields. In all, 128 samples, the levels of each of seven Fusarium Head Blight species and of 12 related mycotoxins were quantified. The results showed that F. graminearum was the most frequently observed species at harvest, followed by F. avenaceum and M. nivale. In the pre-harvest samples, only F. graminearum and M. nivale were relevant. The highest incidence and concentrations of mycotoxins were found for deoxynivalenol, followed by zearalenone and beauvericin, both pre-harvest and at harvest. Other toxins frequently found – for the first time in the Netherlands – included T-2 toxin, HT-2 toxin, and moniliformin. The levels of deoxynivalenol were positively related to F. graminearum levels, as well as to zearalenone levels. Other relationships could not be established. The current approach taken in collecting wheat samples and quantifying the presence of Fusarium Head Blight species and related mycotoxins is an efficient method to obtain insight into the occurrence of these species and toxins in wheat grown under natural environmental conditions. It is recommended that this survey be repeated for several years to establish inter-annual variability in both species composition and mycotoxin occurrence.
A framework for quantifying net benefits of alternative prognostic models
Rapsomaniki, E. ; White, I.R. ; Wood, A.M. ; Thompson, S.G. ; Feskens, E.J.M. ; Kromhout, D. - \ 2012
Statistics in Medicine 31 (2012)2. - ISSN 0277-6715 - p. 114 - 130.
coronary heart-disease - cardiovascular-disease - risk score - predictive ability - roc curve - reclassification - statins - cohort - metaanalysis - validation
New prognostic models are traditionally evaluated using measures of discrimination and risk reclassification, but these do not take full account of the clinical and health economic context. We propose a framework for comparing prognostic models by quantifying the public health impact (net benefit) of the treatment decisions they support, assuming a set of predetermined clinical treatment guidelines. The change in net benefit is more clinically interpretable than changes in traditional measures and can be used in full health economic evaluations of prognostic models used for screening and allocating risk reduction interventions. We extend previous work in this area by quantifying net benefits in life years, thus linking prognostic performance to health economic measures; by taking full account of the occurrence of events over time; and by considering estimation and cross-validation in a multiple-study setting. The method is illustrated in the context of cardiovascular disease risk prediction using an individual participant data meta-analysis. We estimate the number of cardiovascular-disease-free life years gained when statin treatment is allocated based on a risk prediction model with five established risk factors instead of a model with just age, gender and region. We explore methodological issues associated with the multistudy design and show that cost-effectiveness comparisons based on the proposed methodology are robust against a range of modelling assumptions, including adjusting for competing risks
Revisiting land cover observations to address the needs of the climate modeling community
Bontemps, S. ; Herold, M. ; Kooistra, L. ; Groenestijn, A. van; Hartley, A. ; Arino, O. ; Moreau, I. ; Defourny, P. - \ 2012
Biogeosciences 9 (2012). - ISSN 1726-4170 - p. 2145 - 2157.
time-series - satellite - validation - resolution - system
Improving systematic observations of land cover, as an Essential Climate Variable, should contribute to a better understanding of the global climate system and thus improve our ability to predict climatic change. The aim of this paper is to bring global land cover observations closer to meeting the needs of climate science. First, consultation mechanisms were established with the climate modeling community to identify its specific requirements in terms of satellite-based global land cover products. This assessment highlighted specific needs in terms of land cover characterization, accuracy of products, as well as stability and consistency needs that are currently not met or even addressed. The current land cover representation and mapping techniques were then called into question to specifically focus on the critical need of stable products expressed by climate users. Decoupling the stable and dynamic components of the land cover characterization and using a multi-year dataset were proposed as two key approaches to allow generating consistent suites of global land cover products over time.
Estimating regional winter wheat yield with WOFOST through the assimilation of green area index retrieved from MODIS observations
Wit, A.J.W. de; Duveiller, G. ; Defourny, P. - \ 2012
Agricultural and Forest Meteorology 164 (2012). - ISSN 0168-1923 - p. 39 - 52.
remotely-sensed data - crop yield - ndvi data - spatial-resolution - model - validation - simulation - vegetation - radiation - avhrr
Here, we describe and test a method for optimising winter wheat green area index (GAI) simulated with the WOFOST crop model using MODIS estimates of GAI in the Walloon region of Belgium. Detailed crop type maps during the period of 2000–2009 were used to derive time series of crop-specific GAI by selecting only the 250-m MODIS pixels that have at least 75% purity of the target crop. Two important model parameters were optimised by minimising the difference between the simulated and observed GAI for each individual pixel and year. The resulting year-specific joint parameter distributions were then used to run an ensemble of crop simulations in which the ensemble was initialised by sampling from the joint distribution of the corresponding year. The semi-variograms of the retrieved parameters revealed that the spatial patterns were consistent with agricultural practices and that seasonal characteristics of weather patterns in Wallonia can explain – at least partially – the temporal variability observed in the retrieved parameter distributions. Finally, the results of the average ensemble crop simulation were aggregated to the provincial and regional levels. A validation using yields reported by EUROSTAT over the period 2000–2009 revealed that assimilating MODIS with GAI provides an improved relationship between simulation results and reported yields at the regional level.
Cost Analysis of Various Low Pathogenic Avian Influenza Surveillance Systems in the Dutch Egg Layer Sector
Rutten, N. ; Gonzales, J.L. ; Elbers, A.R. ; Velthuis, A.G.J. - \ 2012
PLoS ONE 7 (2012)4. - ISSN 1932-6203 - 9 p.
poultry - risk - viruses - epidemiology - netherlands - validation - chickens
Background As low pathogenic avian influenza viruses can mutate into high pathogenic viruses the Dutch poultry sector implemented a surveillance system for low pathogenic avian influenza (LPAI) based on blood samples. It has been suggested that egg yolk samples could be sampled instead of blood samples to survey egg layer farms. To support future decision making about AI surveillance economic criteria are important. Therefore a cost analysis is performed on systems that use either blood or eggs as sampled material. Methodology/Principal Findings The effectiveness of surveillance using egg or blood samples was evaluated using scenario tree models. Then an economic model was developed that calculates the total costs for eight surveillance systems that have equal effectiveness. The model considers costs for sampling, sample preparation, sample transport, testing, communication of test results and for the confirmation test on false positive results. The surveillance systems varied in sampled material (eggs or blood), sampling location (farm or packing station) and location of sample preparation (laboratory or packing station). It is shown that a hypothetical system in which eggs are sampled at the packing station and samples prepared in a laboratory had the lowest total costs (i.e. € 273,393) a year. Compared to this a hypothetical system in which eggs are sampled at the farm and samples prepared at a laboratory, and the currently implemented system in which blood is sampled at the farm and samples prepared at a laboratory have 6% and 39% higher costs respectively. Conclusions/Significance This study shows that surveillance for avian influenza on egg yolk samples can be done at lower costs than surveillance based on blood samples. The model can be used in future comparison of surveillance systems for different pathogens and hazards
Bead-based suspension array for simultaneous detection of antibodies against the Rift Valley fever virus nucleocapsid and Gn glycoprotein
Wal, F.J. van der; Achterberg, R.P. ; Boer, S.M. de; Boshra, H. ; Brun, A. ; Maassen, C.B.M. ; Kortekaas, J.A. - \ 2012
Journal of Virological Methods 183 (2012)2. - ISSN 0166-0934 - p. 99 - 105.
linked-immunosorbent-assay - domestic ruminants - indirect elisa - igm antibodies - capture elisa - nss protein - n-protein - humans - validation - sandwich
A multiplex bead-based suspension array was developed that can be used for the simultaneous detection of antibodies against the surface glycoprotein Gn and the nucleocapsid protein N of Rift Valley fever virus (RVFV) in various animal species. The N protein and the purified ectodomain of the Gn protein were covalently linked to paramagnetic Luminex beads. The performance of the resulting multiplex immunoassay was evaluated by testing a comprehensive and well-characterized panel of sera from sheep, cattle and humans. The suitability of this multiplex immunoassay to differentiate infected from vaccinated animals (DIVA) was investigated by testing sera from lambs vaccinated with a paramyxovirus vaccine vector expressing the RVFV surface glycoproteins Gn and Gc. The results suggest that the bead-based suspension array can be used as a DIVA assay to accompany several recently developed experimental vaccines that are based on RVFV glycoproteins, and are devoid of the N protein.
Parameterizing the Leaching Surface by Combining Curve-Fitting for Solute Breakthrough and for Spatial Solute Distribution
Bloem, E. ; Gee, M. de; Rooij, G.H. de - \ 2012
Transport in Porous Media 92 (2012)3. - ISSN 0169-3913 - p. 667 - 685.
unsaturated flow - transport models - saturated soil - water - dispersion - variability - validation - zone
Multi-compartment samplers (MCSs) measure unsaturated solute transport in space and time at a given depth. Sorting the breakthrough curves (BTCs) for individual compartments in descending order of total solute amount and plotting in 3D produces the leaching surface. The leaching surface is a useful tool to organize, present, and analyze MCS data. We present a novel method to quantitatively characterize leaching surfaces. We fitted a mean pore-water velocity and a dispersion coefficient to each BTC, and then approximated their values by functions of the rank order of the BTCs. By combining the parameters of these functions with those of the Beta distribution fitted to the spatial distribution of solutes, we described an entire leaching surface by four to eight parameters. This direct characterization method allows trends to be subtracted from the observations, and incorporates the effects of local heterogeneity. The parametric fit creates the possibility to quantify concisely the leaching behavior of a soil in a given climate under given land use, and eases the quantitative comparison of spatio-temporal leaching behavior in different soils and climates.
Nutrient-rich foods in relation to various measures of anthropometry
Streppel, M.T. ; Groot, C.P.G.M. de; Feskens, E.J.M. - \ 2012
Family Practice 29 (2012)Suppl. 1. - ISSN 0263-2136 - p. i36 - i43.
dietary-intake - rotterdam - index - validation - density - obesity - disease
Background. Nutrient quality systems, for example the nutrient-rich foods (NRF) index, measure the nutrient quality of individual foods and may be used to assess the nutrient density of the overall diet. It is not yet known whether the NRF index is helpful in weight management. We hypothesize that a nutrient-dense diet is associated with a lower body weight and waist circumference. Objective. The objective of the present study was to examine the association between the NRF index and various measures of anthropometry. Methods. This study was carried out in a sample of 2044 men and 2925 women, aged =55 years, participating in a community-based prospective cohort study in Rotterdam, The Netherlands. The NRF9.3 algorithms were used to estimate the nutrient density of the subjects’ diets. Linear regression was used to examine the association between the NRF index scores and body mass index (BMI), body weight, waist circumference, wait-to-hip ratio and waist-to-height ratio. Results. Subjects with a high NRF9.3 index score had a lower energy intake (EI) as compared to those with low NRF9.3 index score. However, after adjustment for age, gender and other confounders, the NRF9.3 index score as well as the Nutrient Rich 9 index score were positively associated with BMI, body weight, waist circumference and waist-to-height ratio. Conclusions. Although subjects with a high NRF9.3 index score had a lower EI than those subjects with a low index score, their BMI, body weight, waist circumference and waist-to-height ratio was higher. The association between nutrient quality and body composition is therefore complex
Risk prediction of incident coronary heart disease in the Netherlands: re-estimantion and improvement of the SCORE risk function
Merry, A.H. ; Boer, J.M.A. ; Schouten, L.J. ; Ambergen, T. ; Steyerberg, E.W. ; Feskens, E.J.M. ; Verschuren, W.M.M. ; Gorgels, A.P. ; Brandt, P.A. van den - \ 2012
European Journal of Preventive Cardiology 19 (2012)4. - ISSN 2047-4873 - p. 840 - 848.
global cardiovascular risk - c-reactive protein - clinical-practice - myocardial-infarction - roc curve - validation - framingham - reclassification - mortality - models
Aims: To re-estimate the SCORE risk function using individual data on risk factors and coronary heart disease (CHD) incidence from the Dutch Cardiovascular Registry Maastricht (CAREMA) population-based cohort study; to evaluate changes that may improve risk prediction after re-estimation; and to compare the performance of the resulting CAREMA risk function with that of existing risk scores. Methods and results: The cohort consisted of 21,148 participants, born in 1927–1977 and randomly sampled from the Maastricht region in 1987–1997. After follow-up (median 10.9 years), 783 incident CHD cases occurred. Model performance was assessed by discrimination and calibration. The additional value of including other risk factors or current risk factors in a different manner was evaluated using the net reclassification index (NRI). The c statistic of the re-estimated SCORE model was 0.799 (95% CI 0.782–0.816). Separating the total/high-density lipoprotein (HDL) cholesterol ratio into total and HDL cholesterol levels did not improve the c statistic (p = 0.22), but reclassified 6.0% of the participants into a more appropriate risk category (p <0.001) compared with the re-estimated model. The resulting CAREMA function reclassified 28% of the participants into a more appropriate risk category than the Framingham score. Compared with the SCORE functions for high- and low-risk regions, the NRIs were 28% and 35%, respectively, which can largely be explained by the difference in outcome definition (CHD incidence vs. CHD mortality). Conclusion: In this Dutch population, a re-estimated SCORE function with total and HDL cholesterol levels instead of the cholesterol ratio can be used for the risk prediction of CHD incidence.
The fate of evaporated water from the Ganges basin
Tuinenburg, O.A. ; Hutjes, R.W.A. ; Kabat, P. - \ 2012
Journal of Geophysical Research: Atmospheres 117 (2012)D1. - ISSN 2169-897X
hydrologic-cycle - soil-moisture - global energy - part i - precipitation - irrigation - monsoon - model - validation - vapor
This research studies river basin moisture recycling rates in order to determine the atmospheric part of the water cycle and the influence of the land surface there on. For river basins in India (Ganges and Indus), the fraction of evaporation that falls again as precipitation in the same river basin (the moisture recycling) is determined. Furthermore, the seasonal variance of moisture recycling and the fraction of precipitation that originates from evaporation from the same river basin is quantified. Using a quasi-isentropic moisture tracking scheme, evaporation from land surfaces in India is tracked through the atmosphere until precipitation brings it back to the land surface. This scheme is forced with ERA-Interim reanalysis data from 1990 to 2009. With the information about the atmospheric paths of water vapor, the distance between evaporation and precipitation location is determined. To get an approximation of the influence of land use on the atmospheric moisture budget, the atmospheric paths of water vapor from two bordering areas with different evaporative regimes are compared. Results show a strong annual cycle in the recycling ratio. For the Ganges basin, the recycling ranges from 5% during the winter months (November–March) to 60% during the June–July–August season. The comparison of two focus areas in the Ganges basin with a difference in March–August evaporation shows that during the premonsoon months (March–May), up to 70% of the evaporation difference between the two areas recycles within the Ganges basin. Analysis of the soil moisture nudging terms in ERA-Interim compared to independent irrigation data strongly suggest this evaporation difference can be attributed to large-scale irrigation. The importance of basin moisture recycling for precipitation shows an annual cycle as well. An annual average of 4.5% of Ganges precipitation originates from water evaporating in the Ganges basin. During the dry winter monsoon, any precipitation originates from sources outside the basin. During March–April–May and October–November, 10% of the precipitation originates from evaporation within the basin. During the summer monsoon season, the large influx of moisture from the Indian Ocean dominates the precipitation, and recycling is 5% of precipitation.
Predicting urinary creatinine excretion and its usefulness to identify incomplete 24h urine collections
Keyzer, W. de; Huybrechts, I. ; Dekkers, A.L.M. ; Geelen, A. ; Crispim, S.P. ; Hulshof, P.J.M. ; Andersen, L.F. ; Rehurkova, I. ; Ruprich, J. ; Volatier, J.L. ; Maele, G. van; Slimani, N. ; Veer, P. van 't; Boer, E. de; Henauw, S. de - \ 2012
The British journal of nutrition 108 (2012)6. - ISSN 0007-1145 - p. 1118 - 1125.
4-aminobenzoic acid - european centers - completeness - potassium - diet - validation - stability - recalls - protein - sodium
Studies using 24 h urine collections need to incorporate ways to validate the completeness of the urine samples. Models to predict urinary creatinine excretion (UCE) have been developed for this purpose; however, information on their usefulness to identify incomplete urine collections is limited. We aimed to develop a model for predicting UCE and to assess the performance of a creatinine index using para-aminobenzoic acid (PABA) as a reference. Data were taken from the European Food Consumption Validation study comprising two non-consecutive 24 h urine collections from 600 subjects in five European countries. Data from one collection were used to build a multiple linear regression model to predict UCE, and data from the other collection were used for performance testing of a creatinine index-based strategy to identify incomplete collections. Multiple linear regression (n 458) of UCE showed a significant positive association for body weight (ß = 0·07), the interaction term sex × weight (ß = 0·09, reference women) and protein intake (ß = 0·02). A significant negative association was found for age (ß = - 0·09) and sex (ß = - 3·14, reference women). An index of observed-to-predicted creatinine resulted in a sensitivity to identify incomplete collections of 0·06 (95 % CI 0·01, 0·20) and 0·11 (95 % CI 0·03, 0·22) in men and women, respectively. Specificity was 0·97 (95 % CI 0·97, 0·98) in men and 0·98 (95 % CI 0·98, 0·99) in women. The present study shows that UCE can be predicted from weight, age and sex. However, the results revealed that a creatinine index based on these predictions is not sufficiently sensitive to exclude incomplete 24 h urine collections.
Calibration of RWEQ in a patchy landscape; a first step towards a regional scale wind erosion model
Youssef, I.F. ; Visser, S.M. ; Karssenberg, D. ; Bruggeman, A. ; Erpul, G. - \ 2012
Aeolian Research 3 (2012)4. - ISSN 1875-9637 - p. 467 - 476.
land management - prediction - validation - transport - sediment - sahel - gis
Despite the fact that wind erosion seriously affects the sustainable use of land in a large part of the world, validated wind erosion model that predicts windblown mass transport on a regional scale is lacking. The objectives of this research were to modify revised wind erosion equation (RWEQ) to estimate soil loss at a field scale in a way that it could operate at a regional scale, to calibrate the model using ground data collected from a field scale representing different land uses in Khanasser valley, Syria, and to estimate the total sediment fluxes (kg m-1) and soil losses (kg m-2) for farming fields. We implemented a modified version of RWEQ that represents wind erosion as a transient process, using time steps of 6 h. Beside this a number of adaptations including estimation of mass flux over the field boundaries, and the routing of sediment have been done. Originally, RWEQ was created and calibrated for application at the scale in USA. Due to the adaptations imparted to the original RWEQ and the different environmental condition in Syria of application areas, an intensive calibration process was required before applying the model to estimate the net soil loss from the experimental fields. The results of this test showed that the modified version of RWEQ provided acceptable predictions for the average mass flux from the measurement plot with a linear regression coefficient of R2 of 0.57 and 0.83 for the (d) test for the 20 wind events at the six tested plots
Empirical characterisation of agent behaviours in socio-ecological systems
Smajgl, A. ; Brown, D.G. ; Valbuena Vargas, D.F. ; Huigen, M.G.A. - \ 2011
Environmental Modelling & Software 26 (2011)7. - ISSN 1364-8152 - p. 837 - 844.
models - validation - decisions - protocol - farmers - lessons
Agent-based modelling has become an important tool to investigate socio-ecological processes. Its use is partially driven by increasing demand from decision makers to provide support for understanding the potential implications of decisions in complex situations. While one of the advantages of agent-based modelling is the ability to simulate the implications of human decision-making processes explicitly, methods for providing empirical support for the representation of the behaviour of human agents have not been structured systematically. This paper develops a framework for the parameterisation of human behaviour in agent-based models and develops twelve distinct sequences for the characterisation and parameterisation of human behaviours. Examples are provided to illustrate the most important sequences. This framework is a first step towards a guide for parameterisation of human behaviour in ABM. A structured discussion within the agent-based community is needed to achieve a more definitive guideline.
Screening methods for the detection of antibiotic residues in slaughter animals: comparison of ther european union Four-Plate Test, the Nouws Antibiotic Test and the Premi Test (applied to muscle and kidney
Pikkemaat, M.G. ; Rapallini, M.L.B.A. ; Zuidema, T. ; Elferink, J.W.A. ; Oostra, S. ; Driessen, J.J.M. - \ 2011
Food Additives & Contaminants. Pt. A, Chemistry, Analysis, Control, Exposure & Risk Assessment 28 (2011)1. - ISSN 1944-0049 - p. 26 - 34.
antimicrobial residues - validation - tissue
Microbial growth inhibition tests are widely used as the primary screening approach for the detection of antibiotic residues in slaughter animals. In this study we evaluated and compared the performance of the European Union Four-Plate Test (EU4pt), the Nouws Antibiotic Test (NAT), and a commercial ampoule test, the Premi(R)Test (applied to both muscle and kidney), by parallel analysis of 735 slaughter animals. The EU4pt only showed significant inhibition with two muscle samples containing 305 mu g kg(-1) doxycycline and 648 mu g kg(-1) tulathromycin, while an maximum residue limit (MRL) violation of 1100 mu g kg(-1) sulfamethazine remained unnoticed. Premi(R)Test-muscle only detected the sulfamethazine containing sample, all other (1.1%) suspect samples appeared false-positive results. The same test applied to kidney yielded 4.1% suspect samples, while the NAT screening (based on analysis of renal pelvis fluid) showed 4.9% suspect results. The vast majority of these samples contained tetracycline and/or aminoglycoside residues. Premi(R)Test-kidney appeared to be more sensitive to aminoglycosides than the NAT screening, which failed to detect an MRL violation of 870 mu g kg(-1) gentamicin in kidney. Detection of less than MRL levels of tetracycline residues by the NAT proved its suitability for this residue group. Whether Premi(R)Test is sufficiently sensitive for accurate tetracycline detection in kidney remains doubtful, although changing over to kidney definitely improved the suitability of Premi(R)Test for the detection of residues in slaughter animals.
Smoking, alcohol consumption, physical activity, and family history and the risks of acute myocardial infarction and unstable angina pectoris: a prospective cohort study
Merry, A.H. ; Boer, J.M.A. ; Schouten, L.J. ; Feskens, E.J.M. ; Verschuren, M.W.W. ; Gorgels, A.P. ; Brandt, P.A. van den - \ 2011
BMC Cardiovascular Disorders 11 (2011). - ISSN 1471-2261
coronary-heart-disease - cardiovascular-disease - parental history - relative validity - northern-ireland - metaanalysis - validation - prevention - prediction - prime
BACKGROUND: Few studies investigated the association between smoking, alcohol consumption, or physical activity and the risk of unstable angina pectoris (UAP), while the strength of these associations may differ compared to other coronary diseases such as acute myocardial infarction (AMI). Therefore, we investigated whether the associations of these lifestyle factors with UAP differed from those with AMI. Additionally, we investigated whether these effects differed between subjects with and without a family history of myocardial infarction (MI). METHODS: The CAREMA study consists of 21,148 persons, aged 20-59 years at baseline and randomly sampled from the Maastricht region in 1987-1997. At baseline, all participants completed a self-administered questionnaire. After follow-up of maximally 16.9 years, 420 AMI and 274 UAP incident cases were registered. Incidence rate ratios (RRs) were estimated using Cox proportional hazards models. RESULTS: For both diseases, smoking increased the risk while alcohol consumption was associated with a protective effect. Associations with both risk factors were stronger for AMI than UAP, although this difference was only statistically significant for smoking. In men, an inverse association was found with physical activity during leisure time which seemed to be stronger for the risk of UAP than of AMI. On the contrary, physical activity during leisure time was associated with an increased risk of both AMI and UAP in women which seemed to be weaker for UAP than for AMI. Except for occupational physical activity in women, no significant interactions on a multiplicative scale were found between the lifestyle factors and family history of MI. Nevertheless, the highest risks were found in subjects with both a positive family history and the most unfavorable level of the lifestyle factors. CONCLUSIONS: The strength of the associations with the lifestyle factors did not differ between AMI and UAP, except for smoking. Furthermore, the effects of the lifestyle factors on the risk of both coronary diseases were similar for subjects with and without a positive family history.
Prevalence of self-reported finger deformations and occupational risk factors among professional cooks: a cross-sectional study
Nagasu, M. ; Sakai, K. ; Ito, A. ; Feskens, E.J.M. ; Tomita, S. ; Temmyo, Y. ; Ueno, M. ; Miyagi, S. - \ 2011
BMC Public Health 11 (2011). - ISSN 1471-2458
radiographic hand osteoarthritis - osteo-arthritis - joint - patterns - women - involvement - population - validation - handedness - sex
Background: Previous studies have pointed out that the school lunch workers in Japan are suffering from work-related disorders including finger deformations. The purpose of this study was to investigate the prevalence of self-reported finger deformations and the association with job-related risk factors. Methods: A cross-sectional questionnaire study of 5,719 subjects (response rate: 81%, 982 men and 4,737 women) was undertaken during September 2003 to February 2004. Results: Finger deformations were found among 11.7% of the men and 35.6% of the women studied, with significant differences among sex, age and sex-age groups. For both men and women the pattern of finger deformations across the hand was similar for the right and the left hand. For women, the deformations were found in about 10% of the distal interphalangeal joints of all fingers. Based on multiple logistic regression analyses, the factors female sex, age, the number of cooked lunches per cook and cooking activities were independently associated with the prevalence of finger deformations. High prevalence odds ratios were found for those frequently carrying or using tools by hands such as delivering containers, distributing meals, preparing dishes, washing equipment, cutting and stirring foods. Conclusions: Among the school lunch workers studied, women had a higher prevalence of finger deformations on all joints of both hands. Various cooking tasks were associated with the prevalence of finger deformations. The results suggest that improvements in working conditions are important for preventing work-related disorders such as finger deformations.
Relative developmental toxicity potencies of retinoids in the embryonic stem cell test compared with their relative potencies in in vivo and two other in vitro assays for developmental toxicity
Louisse, J. ; Gonen, S. ; Rietjens, I. ; Verwei, M. - \ 2011
Toxicology Letters 203 (2011)1. - ISSN 0378-4274 - p. 1 - 8.
13-cis-retinoic acid - comparative teratogenicity - embryotoxicity tests - dose-response - mouse limbs - invitro - rat - isotretinoin - validation - etretin
The present study determines the relative developmental toxicity potencies of retinoids in the embryonic stem (ES)-D3 cell differentiation assay of the embryonic stem cell test, and compares the outcomes with their relative potencies in in vivo and two other in vitro assays for developmental toxicity. The results reveal that the potency ranking obtained in the ES-D3 cell differentiation assay is similar to the reported potency rankings in the two other in vitro assays for developmental toxicity. TTNPB ((E)-4[2-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)-1-propenyl]benzoic acid) was the most potent retinoid, whereas etretinate and retinol had the lowest potency. All-trans-retinoic acid, 13-cis-retinoic acid, 9-cis-retinoic acid and acitretin showed an intermediate potency. In vivo potency rankings of the developmental toxicity of retinoids appear to be dependent on the species and/or exposure regimens used. The obtained in vitro potency ranking does not completely correspond with the in vivo potency rankings, although TTNPB is correctly predicted to be the most potent and retinol the least potent congener. The lack of in vivo kinetic processes in the ES-D3 cell differentiation assay might explain the deviating potency predictions of some retinoids. Therefore, knowledge on the species-dependent in vivo kinetics is essential when using in vitro toxicity data for the estimation of in vivo developmental toxicity potencies within series of related compounds
Self-reported energy intake by FFQ compared with actual energy intake to maintain body weight in 516 adults
Siebelink, E. ; Geelen, A. ; Vries, J.H.M. de - \ 2011
The British journal of nutrition 106 (2011)2. - ISSN 0007-1145 - p. 274 - 281.
food-frequency questionnaire - doubly labeled water - flow-mediated vasodilation - breast-cancer - folic-acid - validation - humans - bioavailability - cholesterol - nutrition
It is generally assumed that a FFQ is not suitable to estimate the absolute levels of individual energy intake. However, in epidemiological studies, reported nutrients by FFQ are often corrected for this intake. The objective of the present study was to assess how accurately participants report their energy intakes by FFQ. We compared reported energy intake with actual energy intake needed to maintain stable body weights during eleven controlled dietary trials. FFQ were developed to capture at least 90 % of energy intake. Participants, 342 women and 174 men, with a mean BMI of 22·8 (sd 3·1) kg/m2 filled out the FFQ just before the trials. Energy intakes during the trials were calculated from provided foods and reported free-food items, representing 90 and 10 % of energy intake, respectively. Mean reported energy intake was 97·5 (sd 12·7) % of actual energy intake during the trials; it was 98·9 (sd 15·2) % for women and 94·7 (sd 16·3) % for men (P = 0·004 for difference between sexes). Correlation coefficients between reported and actual energy intakes were 0·82 for all participants, 0·74 for women and 0·80 for men. Individual reported energy intake as a percentage of actual intake ranged from 56·3 to 159·6 % in women and from 43·8 to 151·0 % in men. In conclusion, the FFQ appeared to be accurate for estimating the mean level of energy intakes of these participants and for ranking them according to their intake. However, the large differences found on the individual level may affect the results of epidemiological studies in an unknown direction if nutrients are corrected for energy intakes reported by FFQ
Respondents' evaluation of the 24-h dietary recall method (EPIC-Soft) in the EFCOVAL Project
Huybrechts, I. ; Geelen, A. ; Vries, J.H.M. de; Casagrande, C. ; Nicolas, G. ; Keyzer, W. de; Lillegaard, I.T.L. ; Ruprich, J. ; Lafay, L. ; Wilson-van den Hooven, E.C. ; Niekerk, E.M. ; Margaritis, I. ; Rehurkova, I. ; Crispim, S.P. ; Freisling, H. ; Henauw, S. de; Slimani, N. - \ 2011
European Journal of Clinical Nutrition 65 (2011). - ISSN 0954-3007 - p. S29 - S37.
multiple-pass method - validation - children - accuracy - centers
Background: To improve participation rate, accuracy and respondents’ compliance, it is important to know the respondents’ viewpoint. Objective: To evaluate respondents’ preferences and perception about the EPIC-Soft (the software developed to conduct 24-h dietary recalls (24-HDRs) in the European Prospective Investigation into Cancer and Nutrition (EPIC) Study) 24-HDR interviews and to compare these preferences and perception between population groups (for example, between genders). Design: Data were collected in Belgium, Czech Republic, France, the Netherlands and Norway in 2007. Two 24-HDRs (face-to-face and telephone administered) were conducted using EPIC-Soft. An evaluation questionnaire on different study aspects was completed by the respondents. Setting: Data were collected in the European Food Consumption Validation Study. Subjects: A convenience sample of 600 apparently healthy men and women, 45–65 years old and including all educational levels, were recruited (120 subjects per country). Differences among population groups were compared by means of the ¿ 2-test. Results: A total of 585 respondents completed the evaluation questionnaire. In all, 88% experienced problems only to a low degree when answering face-to-face and telephone-administered 24-HDR using EPIC-Soft. A total of 15% would have preferred help of another person during the face-to-face interview in the study center (mainly men: P
Potential and requirements for a standarized pan-European food consumption survey using the EPIC-Soft software
Ocke, M.C. ; Slimani, N. ; Brants, H.A.M. ; Buurma-Rethans, E. ; Casagrande, C. ; Nicolas, G. ; Dofkova, M. ; Donne, C. le; Freisling, H. ; Geelen, A. ; Huybrechts, I. ; Keyzer, W. de; Laan, J.D. van der; Lafay, L. ; Lillegaard, I.T.L. ; Niekerk, E.M. ; Vries, J.H.M. de; Wilson-van den Hooven, E.C. ; Boer, E.J. de - \ 2011
European Journal of Clinical Nutrition 65 (2011). - ISSN 0954-3007 - p. S48 - S57.
24-hour diet recall - plasma carotenoids - level correlations - nutrient intake - nutrition - cancer - recommendations - questionnaires - calibration - validation
Background/Objectives: To describe the strengths, limitations and requirements of using EPIC-Soft software (the software developed to conduct 24-h dietary recalls in the European Prospective Investigation into Cancer and Nutrition (EPIC) Study) in pan-European food consumption surveys, and to discuss potentials and barriers for a harmonized pan-European food consumption survey. Subjects/Methods: The paper is based on the experiences in the ‘European Food Consumption and Validation’ Project, which included updating six existing and preparing one new country-specific EPIC-Soft version, applying EPIC-Soft in validation and feasibility studies, and estimating the intake of nutrients and flavoring substances. The experiences were discussed in the September 2009 workshop ‘Pan-European Food Consumption Surveys—for Standardized and Comparable Transnational Data Collection’. Results: EPIC-Soft is suitable for detailed and standardized food consumption data collection in pan-European food consumption surveys. A thorough preparation of all aspects of the food consumption survey is important for the quality and efficiency during data collection and processing. The preparation and data-handling phase of working with EPIC-Soft is labor intensive and requires trained, motivated and qualified personnel. Conclusions: Given the suitability of EPIC-Soft as standardized dietary assessment tool in European dietary monitoring, the proposed strategy toward a pan-European food consumption survey is to prepare well, to allow flexibility in national extensions and to start with a limited number of countries that are interested
The standardized computerized 24-h dietary recall method EPIC-Soft adapted for pan-European dietary monitoring
Slimani, N. ; Casagrande, C. ; Nicolas, G. ; Freisling, H. ; Huybrechts, I. ; Ocke, M.C. ; Niekerk, E.M. ; Rossum, C. van; Bellemans, M. ; Maeyer, M. de; Lafay, L. ; Krems, C. ; Amiano, P. ; Trolle, E. ; Geelen, A. ; Vries, J.H.M. de; Boer, E.J. de - \ 2011
European Journal of Clinical Nutrition 65 (2011)S1. - ISSN 0954-3007 - p. S5 - S15.
nutrition - cancer - calibration - project - validation - rationale - countries - nitrogen - centers - program
Background/Objectives: The EPIC-Soft program (the software initially developed to conduct 24-h dietary recalls (24-HDRs) in the European Prospective Investigation into Cancer and Nutrition (EPIC) Study) was recommended as the best way to standardize 24-HDRs for future pan-European dietary monitoring. Within European Food Consumption Validation (EFCOVAL), EPIC-Soft was adapted and further developed on various aspects that were required to optimize its use. In this paper, we present the structure and main interview steps of the EPIC-Soft program, after implementation of a series of new specifications deemed to satisfy specific requirements of pan-European monitoring surveys and other international studies. Subjects/Methods: Updates to optimize the EPIC-Soft program were ascertained according to the following stepwise approach: (1) identification of requested specifications to be potentially implemented through an ad hoc ‘EPIC-Soft specifications questionnaire’ sent to past, current and possible future users of the software; (2) evaluation of the specifications in collaboration with two ad hoc task force groups and through a workshop; (3) development of a technical solution for each retained specification; (4) implementation of the specifications by software developers; (5) testing and amendment of bugs. Results: A number of new specifications and facilities were implemented to EPIC-Soft program. In addition, the software underwent a full reprogramming and migration to a modern Windows environment, including changes in its internal architecture and user interface. Although the overall concept and structure of the initial software were not changed substantially, these improvements ease the current and future use of EPIC-Soft and increase further its adaptation to other countries and study contexts. Conclusions: EPIC-Soft is enriched with further functions and facilities expected to fulfil specific needs of pan-European dietary monitoring and risk assessment purposes. The validity, feasibility and relevance of this software for different national and international study designs, and the logistical aspects related to its implementation are reported elsewhere.
On the spatio-temporal analysis of hydrological droughts from global hydrological models
Corzo Perez, G. ; Huijgevoort, M.H.J. van; Voss, F. ; Lanen, H.A.J. van - \ 2011
Hydrology and Earth System Sciences 15 (2011). - ISSN 1027-5606 - p. 2963 - 2978.
geiger climate classification - united-states - 20th-century drought - streamflow droughts - water availability - world map - trends - validation - europe - variability
The recent concerns for world-wide extreme events related to climate change have motivated the development of large scale models that simulate the global water cycle. In this context, analysis of hydrological extremes is important and requires the adaptation of identification methods used for river basin models. This paper presents two methodologies that extend the tools to analyze spatio-temporal drought development and characteristics using large scale gridded time series of hydrometeorological data. The methodologies are classified as non-contiguous and contiguous drought area analyses (i.e. NCDA and CDA). The NCDA presents time series of percentages of areas in drought at the global scale and for pre-defined regions of known hydroclimatology. The CDA is introduced as a complementary method that generates information on the spatial coherence of drought events at the global scale. Spatial drought events are found through CDA by clustering patterns (contiguous areas). In this study the global hydrological model WaterGAP was used to illustrate the methodology development. Global gridded time series of subsurface runoff (resolution 0.5°) simulated with the WaterGAP model from land points were used. The NCDA and CDA were developed to identify drought events in runoff. The percentages of area in drought calculated with both methods show complementary information on the spatial and temporal events for the last decades of the 20th century. The NCDA provides relevant information on the average number of droughts, duration and severity (deficit volume) for pre-defined regions (globe, 2 selected hydroclimatic regions). Additionally, the CDA provides information on the number of spatially linked areas in drought, maximum spatial event and their geographic location on the globe. Some results capture the overall spatio-temporal drought extremes over the last decades of the 20th century. Events like the El Niño Southern Oscillation (ENSO) in South America and the pan-European drought in 1976 appeared clearly in both analyses. The methodologies introduced provide an important basis for the global characterization of droughts, model inter-comparison of drought identified from global hydrological models and spatial event analyses
Classical swine fever virus detection: results of a real-time reverse transcription polymerase chain reaction ring trial conducted in the framework of the European network of excellence for epizootic disease diagnosis and control.
Hoffmann, B. ; Blome, S. ; Bonulauri, P. ; Fernández-Pinero, J. ; Greiser-Wilke, I. ; Haegeman, A. ; Isaksson, M. ; Koenen, F. ; Leblanc, N. ; Leifer, I. ; Potier, M.F. Le; Loeffen, W. ; Rasmussen, T.B. ; Stadejek, T. ; Stahl, K. ; Tignon, M. ; Uttenthal, A. ; Poel, W.H.M. van der - \ 2011
Journal of Veterinary Diagnostic Investigation 23 (2011)5. - ISSN 1040-6387 - p. 999 - 1004.
rt-pcr assay - pestiviruses - validation - infection - virulence - vaccine - taqman - probes - signs - pigs
The current study reports on a real-time reverse transcription polymerase chain reaction (real-time RT-PCR) ring trial for the detection of Classical swine fever virus (CSFV) genomic RNA undertaken by 10 European laboratories. All laboratories were asked to use their routine in-house real-time RT-PCR protocols and a standardized protocol commonly used by the Friedrich-Loeffler-Institute (FLI) on a panel of well-characterized samples. In general, all participants produced results within the acceptable range. The FLI assay, several in-house assays, and the commercial kits had high analytical sensitivity and specificity values. Nevertheless, some in-house systems had unspecific reactions or suboptimal sensitivity with only a single CSFV genotype. Follow-up actions involved either improvement of suboptimal assays or replacement of specific laboratory assays with the FLI protocol, with or without modifications. In conclusion, the ring trial showed reliability of classical swine fever diagnosis on an international level and helped to optimize CSFV-specific RT-PCR diagnostics.
Quantitative trace analysis of eight chloramphenicol isomers in urine by chiral liquid chromatography coupled to tandem mass spectrometry
Berendsen, B.J.A. ; Essers, M.L. ; Stolker, A.A.M. ; Nielen, M.W.F. - \ 2011
Journal of Chromatography. A, Including electrophoresis and other separation methods 1218 (2011)41. - ISSN 0021-9673 - p. 7331 - 7340.
human plasma - antibiotic chloramphenicol - enantiomeric separation - residues - meat - dextramycin - 2002/657/ec - validation - seafood - drugs
Chloramphenicol is a broad-spectrum antibiotic with, apart from its human medicinal use, veterinary abuse in all major food-producing animals. Chloramphenicol occurs in four stereoisomers (all para-nitro substituted) and furthermore four meta-nitro analogs of chloramphenicol exist. In this paper these are referred to as eight chloramphenicol isomers. According to EU regulations an analytical method should be able to discriminate the analyte from interfering substances that might be present in the sample, including isomers. For the first time a quantitative method for the analysis of trace levels of eight chloramphenicol isomers in urine by chiral liquid chromatography in combination with tandem mass spectrometric detection is reported. The separation of the isomers on the analytical column, the clean-up of urine and the selectivity of the monitored product ions turned out to be critical parameters. To obtain reproducible retention isocratic elution on a chiral AGP column was applied. For urine samples matrix compounds present in the final extract caused decreased retention of the isomers on the chiral stationary phase and a lack of chromatographic resolution. Therefore an extended clean-up procedure that combines solid phase extraction and liquid–liquid extraction had to be developed. The final method was fully validated and showed satisfactory performance for all isomers with decision limits (CCa) ranging from 0.005 to 0.03 µg L-1 and within-laboratory reproducibility of all isomers below 20% at the minimum required performance limit level of 0.3 µg L-1. --------------------------------------------------------------------------------
Ground-Based Optical Measurements at European Flux Sites:
Balzarolo, M. ; Anderson, K. ; Nichol, C. ; Elbers, J.A. ; Rossini, M. ; Vescovo, L. - \ 2011
Sensors 11 (2011). - ISSN 1424-8220 - p. 7954 - 7981.
vegetation indexes - spectral reflectance - co2 fluxes - photosynthetic efficiency - ndvi measurements - resolution ndvi - carbon-dioxide - ecosystem - validation - footprint
This paper reviews the currently available optical sensors, their limitations and opportunities for deployment at Eddy Covariance (EC) sites in Europe. This review is based on the results obtained from an online survey designed and disseminated by the Co-cooperation in Science and Technology (COST) Action ESO903—“Spectral Sampling Tools for Vegetation Biophysical Parameters and Flux Measurements in Europe” that provided a complete view on spectral sampling activities carried out within the different research teams in European countries. The results have highlighted that a wide variety of optical sensors are in use at flux sites across Europe, and responses further demonstrated that users were not always fully aware of the key issues underpinning repeatability and the reproducibility of their spectral measurements. The key findings of this survey point towards the need for greater awareness of the need for standardisation and development of a common protocol of optical sampling at the European EC sites
|De invloed van geïdealiseerde mediabeelden op het zelfbeeld van jonge meisjes: Het positieve effect van mediabewustzijn.
Deen, F.S. van der; Schwinghammer, S.A. ; Verkooijen, K.T. - \ 2011
Tijdschrift voor Communicatiewetenschap 39 (2011)3. - ISSN 1384-6930 - p. 90 - 106.
body-image - thin-ideal - sociocultural attitudes - focused anxiety - womens body - models - internalization - validation - impact
This study examines the influence of idealised (extremely attractive) models appearing in beauty advertisements on the self-image of 10-13 year-old girls and investigates the possible protective role of media awareness. Model attractiveness (idealised vs. normally attractive) and media awareness (induced vs. not induced) were manipulated and self-image and internalisation of the Western beauty ideal were measured. Results show that after exposure to beauty advertisements with idealised models, girls with higher induced media awareness had a slightly more positive self-image than girls in whom media awareness was not induced. Moreover, this positive effect of media awareness was more pronounced within the group of girls who highly internalized the Western beauty ideal. It is concluded that media awareness can protect the self-image of young (vulnerable) girls who are exposed to idealised media images.
Bioassay based screening of steroid derivatives in animal feed and supplements
Rijk, J.C.W. ; Ashwin, H.M. ; Kuijk, S.J.A. van; Groot, M.J. ; Heskamp, H.H. ; Bovee, T.F.H. ; Nielen, M.W.F. - \ 2011
Analytica Chimica Acta 700 (2011)1-2. - ISSN 0003-2670 - p. 183 - 188.
testosterone-undecanoate - liquid-chromatography - androgen bioassay - yeast bioassay - validation - urine
Receptor binding transcription activation bioassays are valuable tools for the screening of steroid hormones in animal feed and supplements. However, steroid derivatives often lack affinity for their cognate receptor and do not show any direct hormonal activity by themselves. These compounds are thus not detected by these kinds of bioassays and need a bioactivation step in order to become active, both in vivo and in vitro. In this study a comparison was made between different in vitro activation methods for hormone esters and hormone glycosides. Testosterone acetate and testosterone decanoate were chosen as model compounds for the hormone esters, representing the broad range of steroid esters of varying polarities, while genistin was used as a substitute model for the steroid-glycosides. Concerning bioactivation of the steroids esters, the efficiency for alkaline hydrolysis was 90–100% and much better as compared to enzymatic deconjugation by esterase. As a result 1 µg testosterone ester per gram of animal feed could easily be detected by a yeast androgen bioassay. When comparing different enzyme fractions for deglycosilation, genistin was shown to be deconjugated most efficiently by ß-glucuronidase/aryl sulfatase from Helix pomatia, resulting in a significant increase of estrogenic activity as determined by a yeast estrogen bioassay. In conclusion, chemical and enzymatic deconjugation procedures for ester and glycoside conjugates respectively, resulted in a significant increase in hormonal activity as shown by the bioassay readouts and allowed effective screening of these derivatives in animal feed and feed supplements.
Applicability of a yeast bioassay in the detection of steroid esters in hair
Becue, I. ; Bovee, T.F.H. ; Poucke, C. ; Groot, M.J. ; Nielen, M.W.F. ; Peteghem, C. van - \ 2011
Analytical and Bioanalytical Chemistry 399 (2011)3. - ISSN 1618-2642 - p. 1031 - 1039.
green fluorescent protein - tandem mass-spectrometry - estrogenic activity - bovine hair - estradiol benzoate - anabolic-steroids - calf urine - validation - samples - expression
The aim of the present study was to demonstrate the applicability of a yeast androgen and estrogen bioassay in the detection of steroid esters in hair samples of animals treated with a hormone ester cocktail. The outcome of the activity screenings was critically compared with the results previously obtained with LC-MS/MS analysis. Hair samples of one pour-on treated animal, 10 ml DMSO containing 25 mg estradiol benzoate (EB), 60 mg testosterone decanoate (TD) and 60 mg testosterone cypionate (TC), were selected and analyzed with the androgen and estrogen yeast bioassay. Results showed that by the introduction of a hydrolysis step, bioassays can be used to screen for the presence of hormone esters in hair samples. Based on the difference in fluorescence responses between the nonhydrolyzed and the hydrolyzed hair samples, it was possible to detect the presence of EB up to at least 56 days after a single pour-on treatment and to detect the presence of TC and TD up to at least 14 days after the treatment. Although the LC-MS/MS analysis could detect TC and TD up to 49 days after treatment, bioassays have the advantage that they can also detect any (un)known steroid ester. Keywords Testosterone ester . Estradiol benzoate . Yeast bioassay . Untargeted analysis . Hair
Comparing four methods to estimate usual intake distributions
Souverein, O.W. ; Dekkers, A.L. ; Geelen, A. ; Haubrock, J. ; Vries, J.H.M. de; Ocke, M.C. ; Harttig, U. ; Boeing, H. ; Veer, P. van 't - \ 2011
European Journal of Clinical Nutrition 65 (2011). - ISSN 0954-3007 - p. S92 - S101.
short-term measurements - episodically consumed foods - consumption - exposure - model - population - validation - nutrients - centers - recall
Background/Objectives: The aim of this paper was to compare methods to estimate usual intake distributions of nutrients and foods. As ‘true’ usual intake distributions are not known in practice, the comparison was carried out through a simulation study, as well as empirically, by application to data from the European Food Consumption Validation (EFCOVAL) Study in which two 24-h dietary recalls (24-HDRs) and food frequency data were collected. The methods being compared were the Iowa State University Method (ISU), National Cancer Institute Method (NCI), Multiple Source Method (MSM) and Statistical Program for Age-adjusted Dietary Assessment (SPADE). Subjects/Methods: Simulation data were constructed with varying numbers of subjects (n), different values for the Box–Cox transformation parameter (¿BC) and different values for the ratio of the within- and between-person variance (rvar). All data were analyzed with the four different methods and the estimated usual mean intake and selected percentiles were obtained. Moreover, the 2-day within-person mean was estimated as an additional ‘method’. These five methods were compared in terms of the mean bias, which was calculated as the mean of the differences between the estimated value and the known true value. The application of data from the EFCOVAL Project included calculations of nutrients (that is, protein, potassium, protein density) and foods (that is, vegetables, fruit and fish). Results: Overall, the mean bias of the ISU, NCI, MSM and SPADE Methods was small. However, for all methods, the mean bias and the variation of the bias increased with smaller sample size, higher variance ratios and with more pronounced departures from normality. Serious mean bias (especially in the 95th percentile) was seen using the NCI Method when rvar=9, ¿BC=0 and n=1000. The ISU Method and MSM showed a somewhat higher s.d. of the bias compared with NCI and SPADE Methods, indicating a larger method uncertainty. Furthermore, whereas the ISU, NCI and SPADE Methods produced unimodal density functions by definition, MSM produced distributions with ‘peaks’, when sample size was small, because of the fact that the population's usual intake distribution was based on estimated individual usual intakes. The application to the EFCOVAL data showed that all estimates of the percentiles and mean were within 5% of each other for the three nutrients analyzed. For vegetables, fruit and fish, the differences were larger than that for nutrients, but overall the sample mean was estimated reasonably. Conclusions: The four methods that were compared seem to provide good estimates of the usual intake distribution of nutrients. Nevertheless, care needs to be taken when a nutrient has a high within-person variation or has a highly skewed distribution, and when the sample size is small. As the methods offer different features, practical reasons may exist to prefer one method over the other.
Uncertainty in intake due to portion size estimation in 24-hour recalls varies between food groups
Souverein, O.W. ; Boer, W.J. de; Geelen, A. ; Voet, H. van der; Vries, J.H.M. de; Feinberg, M. ; Veer, P. van 't - \ 2011
The Journal of Nutrition 141 (2011)7. - ISSN 0022-3166 - p. 1396 - 1401.
statistical-methods - dietary-intake - photographs - population - distributions - consumption - validation - selection - accuracy - validity
Portion size estimation is expected to be one of the largest sources of uncertainty in dietary assessment of the individual. Therefore, we demonstrated a method to quantify uncertainty due to portion size estimation in the usual intake distributions of vegetables, fruit, bread, protein, and potassium. Dutch participants of the European Food Consumption Validation study completed 2 nonconsecutive 24-h recall interviews. In short, the uncertainty analysis consists of Monte Carlo simulations drawing values for portion size from lognormal uncertainty distributions. The uncertainty of the usual intake distribution and accompanying parameters (IQR and the shrinkage factor) were estimated. For the food groups, portion size uncertainty had the greatest effect for vegetables and the least for fruit: the relative 95% uncertainty interval (UI) of the IQR of the usual intake distribution was 0.61–1.35 for vegetables, 0.77–1.24 for bread, and 0.99–1.10 for fruit. For protein and potassium, the resulting relative width of the UI of the IQR for portion size uncertainty are similar: 0.88–1.14 for protein and 0.86–1.14 for potassium. Furthermore, a sensitivity analysis illustrated the importance of the specified uncertainty distributions. The examples show that uncertainty in portion sizes may be more important for some foods such as vegetables. This may reflect differential quantification errors by food groups that deserve further consideration. In conclusion, the presented methodology allows the important quantification of portion size uncertainty and extensions to include other sources of uncertainty is straightforward.
Revisiting Kappa to account for change in the accuracy assessment of land-use models
Vliet, J. van; Bregt, A.K. ; Hagen-Zanker, A. - \ 2011
Ecological Modelling 222 (2011)8. - ISSN 0304-3800 - p. 1367 - 1375.
spatial simulation-models - validation - maps - landscape - cover - performance - skill
Land-use change models are typically calibrated to reproduce known historic changes. Calibration results can then be assessed by comparing two datasets: the simulated land-use map and the actual land-use map at the same time. A common method for this is the Kappa statistic, which expresses the agreement between two categorical datasets corrected for the expected agreement. This expected agreement is based on a stochastic model of random allocation given the distribution of class sizes. However, when a model starts from an initial land-use map and makes changes to it, that stochastic model does not pose a meaningful reference level. This paper introduces KSimulation, a statistic that is identical in form to the Kappa statistic but instead applies a more appropriate stochastic model of random allocation of class transitions relative to the initial map. The new method is illustrated on a simple example and then the results of the Kappa statistic and KSimulation are compared using the results of a land-use model. It is found that only KSimulation truly tests models in their capacity to explain land-use changes over time, and unlike Kappa it does not inflate results for simulations where little change takes place over time.
Simulation of fruit-set and trophic competition and optimization of yield advantages in six Xapsicum cultivars using functional-tructural plant modelling
Ma, Y.T. ; Wubs, A.M. ; Mathieu, A. ; Heuvelink, E. ; Zhu, J.Y. ; Hu, B.G. ; Cournede, P.H. ; Reffye, P. de - \ 2011
Annals of Botany 107 (2011)5. - ISSN 0305-7364 - p. 793 - 803.
sweet-pepper - sink strength - annuum-l - growth - abscission - patterns - cucumber - validation - irradiance - components
Background and aims - Many indeterminate plants can have wide fluctuations in the pattern of fruit-set and harvest. Fruit-set in these types of plants depends largely on the balance between source (assimilate supply) and sink strength (assimilate demand) within the plant. This study aims to evaluate the ability of functional–structural plant models to simulate different fruit-set patterns among Capsicum cultivars through source–sink relationships. Methods - A greenhouse experiment of six Capsicum cultivars characterized with different fruit weight and fruit-set was conducted. Fruit-set patterns and potential fruit sink strength were determined through measurement. Source and sink strength of other organs were determined via the GREENLAB model, with a description of plant organ weight and dimensions according to plant topological structure established from the measured data as inputs. Parameter optimization was determined using a generalized least squares method for the entire growth cycle. Key Results and Conclusions - Fruit sink strength differed among cultivars. Vegetative sink strength was generally lower for large-fruited cultivars than for small-fruited ones. The larger the size of the fruit, the larger variation there was in fruit-set and fruit yield. Large-fruited cultivars need a higher source–sink ratio for fruit-set, which means higher demand for assimilates. Temporal heterogeneity of fruit-set affected both number and yield of fruit. The simulation study showed that reducing heterogeneity of fruit-set was obtained by different approaches: for example, increasing source strength; decreasing vegetative sink strength, source–sink ratio for fruit-set and flower appearance rate; and harvesting individual fruits earlier before full ripeness. Simulation results showed that, when we increased source strength or decreased vegetative sink strength, fruit-set and fruit weight increased. However, no significant differences were found between large-fruited and small-fruited groups of cultivars regarding the effects of source and vegetative sink strength on fruit-set and fruit weight. When the source–sink ratio at fruit-set decreased, the number of fruit retained on the plant increased competition for assimilates with vegetative organs. Therefore, total plant and vegetative dry weights decreased, especially for large-fruited cultivars. Optimization study showed that temporal heterogeneity of fruit-set and ripening was predicted to be reduced when fruits were harvested earlier. Furthermore, there was a 20 % increase in the number of extra fruit set
Impact of reservoirs on river discharge and irrigation water supply during the 20th century
Biemans, H. ; Haddeland, I. ; Kabat, P. ; Ludwig, F. ; Hutjes, R.W.A. - \ 2011
Water Resources Research 47 (2011)3. - ISSN 0043-1397 - 15 p.
global vegetation model - climate-change - integrated model - resources - dams - basin - requirements - groundwater - validation - sediment
This paper presents a quantitative estimation of the impact of reservoirs on discharge and irrigation water supply during the 20th century at global, continental, and river basin scale. Compared to a natural situation the combined effect of reservoir operation and irrigation extractions decreased mean annual discharge to oceans and significantly changed the timing of this discharge. For example, in Europe, May discharge decreased by 10%, while in February it increased by 8%. At the end of the 20th century, reservoir operations and irrigation extractions decreased annual global discharge by about 2.1% (930 km3 yr-1). Simulation results show that reservoirs contribute significantly to irrigation water supply in many regions. Basins that rely heavily on reservoir water are the Colorado and Columbia River basins in the United States and several large basins in India, China, and central Asia (e.g., in the Krishna and Huang He basins, reservoirs more than doubled surface water supply). Continents gaining the most are North America, Africa, and Asia, where reservoirs supplied 57, 22, and 360 km3 yr-1 respectively between 1981–2000, which is in all cases 40% more than the availability in the situation without reservoirs. Globally, the irrigation water supply from reservoirs increased from around 18 km3 yr-1 (adding 5% to surface water supply) at the beginning of the 20th century to 460 km3 yr-1 (adding almost 40% to surface water supply) at the end of the 20th century. The analysis is performed using a newly developed and validated reservoir operation scheme within a global-scale hydrology and vegetation model (LPJmL)
Realized habitats of early-stage North Sea herring: looking for signals of environmental change
Rockmann, C. ; Dickey-Collas, M. ; Payne, M.R. ; Hal, R. van - \ 2011
ICES Journal of Marine Science 68 (2011)3. - ISSN 1054-3139 - p. 537 - 546.
cod gadus-morhua - climate-change - baltic sea - ecosystem model - atlantic - fish - variability - l. - populations - validation
Realized habitats of North Sea herring for two larval and two juvenile stages were estimated over the past 30 years, using abundances from surveys tied to modelled estimates of temperature and salinity. Newly hatched larvae (NHL) were found mainly in water masses of 9–11°C, pre-metamorphosis larvae (PML) around 5–6°C, juveniles aged 0 in summer around 13–14°C, and juveniles aged 1 in winter around 4–5°C. The median salinity in which the NHL were distributed was 34.4–35.0 and 33.7–33.9, respectively, for PML and juveniles. Interannual variations in temperature and geographic variables in the North Sea were compared with the time-series of realized habitats. The realized temperature habitats of the NHL did not change over time, but the habitat of juveniles in summer may be associated with higher temperatures. Juveniles aged 1 in winter are found in waters colder than the average for the North Sea, a result also reflected in their geographic shift east into shallower water. The results suggest that juveniles could be limited by temperature, but may also track changes in food or predator distribution, and/or internal population dynamics. Time-series analysis of realized salinity habitats was not possible with the available data because of differences between model outputs
Food compensation: do exercise ads change food intake?
Kleef, E. van; Shimizu, M. ; Wansink, B. - \ 2011
International journal of behavioral nutrition and physical activity 8 (2011). - ISSN 1479-5868 - 10 p.
physical-activity - social-behavior - self-esteem - healthy - weight - adolescents - validation - activation - mechanisms - children
Background: Past research has shown that promotional messages such as food advertising influence food consumption. However, what has gone largely unexplored is the effect of exercise advertising on food intake. This study experimentally tested the effects of exposure to exercise commercials on food intake at a lunch meal as compared to the effects of control commercials. Methods: Prior to eating lunch, 125 participants (71 women, 54 men) watched 8 commercials, either all related to exercise or fitness (n = 67) or neutral products (i.e. car insurance) (n = 58). The meal consisted of a pasta dish with tomato sauce, salad and chocolate pudding. The post-lunch questionnaire included questions about body mass index, exercise habits, motivation and dietary restraint. Results: Participants exposed to exercise commercials reduced their caloric intake by 21.7% relative to the control condition. Additionally, watching exercise messages increased the perceived healthiness and liking of the meal. Although exercise habits and intentions did not moderate the effect of commercial condition on food intake, we also found that this intake reduction was driven by participants with higher body mass index levels. Conclusions: These results imply that exercise messages may serve as a reminder of the link between food and physical activity and affect food consumption. It also highlights the need for increased awareness that these messages have powerful influences not only on exercise behavior, but also on closely related behaviors such as eating
Estimating forest variables from top-of-atmosphere radiance satellite measurements using coupled radiative transfer models
Laurent, V.C.E. ; Verhoef, W. ; Clevers, J.G.P.W. ; Schaepman, M.E. - \ 2011
Remote Sensing of Environment 115 (2011)4. - ISSN 0034-4257 - p. 1043 - 1052.
leaf-area index - bidirectional reflectance - biophysical variables - global products - canopy - vegetation - inversion - validation - simulation - albedo
Traditionally, it is necessary to pre-process remote sensing data to obtain top of canopy (TOC) reflectances before applying physically-based model inversion techniques to estimate forest variables. Corrections for atmospheric, adjacency, topography, and surface directional effects are applied sequentially and independently, accumulating errors into the TOC reflectance data, which are then further used in the inversion process. This paper presents a proof of concept for demonstrating the direct use of measured top-of-atmosphere (TOA) radiance data to estimate forest biophysical and biochemical variables, by using a coupled canopy–atmosphere radiative transfer model. Advantages of this approach are that no atmospheric correction is needed and that atmospheric, adjacency, topography, and surface directional effects can be directly and more accurately included in the forward modelling. In the case study, we applied both TOC and TOA approaches to three Norway spruce stands in Eastern Czech Republic. We used the SLC soil–leaf–canopy model and the MODTRAN4 atmosphere model. For the TOA approach, the physical coupling between canopy and atmosphere was performed using a generic method based on the 4-stream radiative transfer theory which enables full use of the directional reflectance components provided by SLC. The method uses three runs of the atmosphere model for Lambertian surfaces, and thus avoids running the atmosphere model for each new simulation. We used local sensitivity analysis and singular value decomposition to determine which variables could be estimated, namely: canopy cover, fraction of bark, needle chlorophyll, and dry matter content. TOC and TOA approaches resulted in different sets of estimates, but had comparable performance. The TOC approach, however, was at its best potential because of the flatness and homogeneity of the area. On the contrary, the capacities of the TOA approach would be better exploited in heterogeneous rugged areas. We conclude that, having similar performance, the TOA approach should be preferred in situations where minimizing the pre-processing is important, such as in data assimilation and multi-sensor studies.
Mapping cumulative environmental risks: examples from the EU NoMiracle project
Pistocchi, A. ; Groenwold, J. ; Lahr, J. ; Loos, M. ; Mujica, M. ; Ragas, A.M.J. ; Rallo, R. ; Sala, S. ; Schlink, U. ; Strebel, K. ; Vighi, M. ; Vizcaino, P. - \ 2011
Environmental Modeling and Assessment 16 (2011)2. - ISSN 1420-2026 - p. 119 - 133.
self-organizing map - surface waters - pesticide mixtures - voc concentrations - independent action - exposure - indoor - contamination - validation - substances
We present examples of cumulative chemical risk mapping methods developed within the NoMiracle project. The different examples illustrate the application of the concentration addition (CA) approach to pesticides at different scale, the integration in space of cumulative risks to individual organisms under the CA assumption, and two techniques to (1) integrate risks using data-driven, parametric statistical methods, and (2) cluster together areas with similar occurrence of different risk factors, respectively. The examples are used to discuss some general issues, particularly on the conventional nature of cumulative risk maps, and may provide some suggestions for the practice of cumulative risk mapping.
Are antibiotic screening approaches sufficiently adequate? A proficiency test
Berendsen, B.J.A. ; Pikkemaat, M.G. ; Stolker, A.A.M. - \ 2011
Analytica Chimica Acta 685 (2011)2. - ISSN 0003-2670 - p. 170 - 175.
antimicrobial residues - mass-spectrometry - veterinary drugs - uplc-tof - muscle - milk - laboratories - validation - samples - kidney
A proficiency test including the screening analysis of antibiotics in beef using cryogenicly minced materials was organized by RIKILT in 2009. The test included blank beef samples and beef samples spiked with either flumequine or a combination of lincomycin and spectinomycin around the maximum residue limits . The suitability of the materials was demonstrated with a homogeneity and a stability study. This study showed that cryogenically minced spiked muscle material is suited for proficiency tests aiming at the screening and the confirmatory analysis. Of the 26 participants, 23 carried out their in-house screening approach involving microbial, biochemical or instrumental methods, or a combination of these to cover the broad range of antibiotic groups. The false negative rate was 73% for microbial methods, 50% for biochemical and 22% for instrumental methods. These results indicate that substantial effort is needed to improve screening approaches and that more regular proficiency tests are needed to reveal the shortcomings in the currently applied screening methods.