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Showing papers by "Wageningen University and Research Centre published in 1999"


Journal ArticleDOI
TL;DR: This article conducted a quantitative meta-analysis of country-of-origin effects on three types of product evaluations, viz., perceived quality, attitude, and purchase intention, and found that country of origin has a larger effect on perceived quality than on attitude toward the product or purchase intention.

1,460 citations


Journal ArticleDOI
TL;DR: In this article, the authors examine antecedents of consumer innovativeness in a cross-national context and propose a framework that distinguishes individual difference variables and national cultural variables to distinguish consumer difference variables.
Abstract: The authors examine antecedents of consumer innovativeness in a cross-national context. They propose a framework that distinguishes individual difference variables and national cultural variables. ...

1,166 citations


Journal ArticleDOI
TL;DR: Recent development of indices that integrate the responses of different taxa and trophic groups to perturbation provides a powerful basis for analysis of faunal assemblages in soil as in situ environmental assessment systems.
Abstract: Four of every five multicellular animals on the planet are nematodes. They occupy any niche that provides an available source of organic carbon in marine, freshwater and terrestrial environments. Nematodes vary in sensitivity to pollutants and environmental disturbance. Recent development of indices that integrate the responses of different taxa and trophic groups to perturbation provides a powerful basis for analysis of faunal assemblages in soil as in situ environmental assessment systems.

973 citations


Journal ArticleDOI
TL;DR: "Bacteria have evolved adaptive networks to face the challenges of changing environments and to survive under conditions of stress, therefore the efficiencies of inactivation and preservation methods need to be assessed, especially with regard to the enormous potential of food pathogens to adapt to a wide variety of stress conditions.

443 citations


Journal ArticleDOI
TL;DR: The Southern Great Plains 1997 (SGP97) Hydrology Experiment (a surface soil moisture mapping mission conducted between June 18 and July 17, 1997, in central Oklahoma) was conducted to characterize soil moisture variability within remote sensing footprints (approximately 0.64 km2) with more certainty than would be afforded with conventional gravimetric moisture content sampling.
Abstract: Surface soil moisture content is highly variable in both space and time. While remote sensing provides an effective methodology for mapping surface moisture content over large areas, it averages within-pixel variability thereby masking the underlying heterogeneity observed at the land surface. This variability must be better understood in order to rigorously evaluate sensor performance and to enhance the utility of the larger-scale remotely sensed averages by quantifying the underlying variability that remote sensing cannot record explicitly. In support of the Southern Great Plains 1997 (SGP97) Hydrology Experiment (a surface soil moisture mapping mission conducted between June 18 and July 17, 1997, in central Oklahoma) an investigation was conducted to characterize soil moisture variability within remote sensing footprints (approximately 0.64 km2) with more certainty than would be afforded with conventional gravimetric moisture content sampling. Nearly every day during the experiment period, portable impedance probes were used to intensively monitor volumetric moisture content in the 0- to 6-cm surface soil layer at six footprint-sized fields scattered over the SGP97 study area. A minimum of 49 daily moisture content measurements were made on most fields. Higher-resolution grid and transect data were also collected periodically. In total, more than 11,000 impedance probe measurements of volumetric moisture content were made at the six sites by over 35 SGP97 participants. The wide spatial distribution of the sites, combined with the intensive, near-daily monitoring, provided a unique opportunity (relative to previous smaller-scale and shorter-duration soil moisture studies) to characterize variations in surface moisture content over a range of wetness conditions. In this paper the range and temporal dynamics of the variability in moisture content within each of the six fields are described, as are general relationships between the variability and footprint-mean moisture content. Results indicate that distinct differences in mean moisture content between the six sites are consistent with variations in soil type, vegetation cover, and rainfall gradients. Within fields the standard deviation, coefficient of variation, skewness, and kurtosis increased with decreasing moisture content; the distribution of surface moisture content evolved from negatively skewed/nonnormal under very wet conditions, to normal in the midrange of mean moisture content, to positively skewed/nonnormal under dry conditions; and agricultural practices of row tilling and terracing were shown to exert a major control on observed moisture content variations. Results presented here can be utilized to better evaluate sensor performance, to extrapolate estimates of subgrid-scale variations in moisture content across the entire SGP97 region, and in the parameterization of soil moisture dynamics in hydrological and land surface models.

385 citations


Journal ArticleDOI
TL;DR: It is shown that the commonly used 2pK models are incapable to incorporate in the adsorption modeling the correct bidentate binding mechanism found by spectroscopy, and the CD-MUSIC model can successfully describe the macroscopic Adsorption phenomena using the surface speciation and binding mechanisms as found bySpectroscopy.

380 citations


Journal ArticleDOI
TL;DR: In this paper, the rates of hydrolysis and biodegradability of six selected components of biowaste were determined as a function of temperature under mesophilic anaerobic conditions.

359 citations


Journal ArticleDOI
TL;DR: Data indicate that histatin 5 is internalized, and targets to the energized mitochondrion, like the biological effects, which was inhibited by mitochondrial inhibitors and high salt conditions.

278 citations


Journal ArticleDOI
TL;DR: In this article, the original allocation of nematode taxa on the colonizer-persister scale, and the tolerance and sensitivity of colonizers and persisters are discussed from an evolutionary viewpoint.
Abstract: Nematodes are increasingly being used in environmental studies. One of the potential parameters to measure the impact of disturbances and to monitor changes in structure and functioning of the below-ground ecosystem is the nematode Maturity Index; an index based on the proportion of colonizers (r-strategists s.l.) and persisters (K-strategists s.l.) in samples. In this paper the original allocation of nematode taxa on the colonizer-persister scale, and the tolerance and sensitivity of colonizers and persisters are discussed from an evolutionary viewpoint. The phenomenon that neither relative egg size nor body length is an unequivocal character to scale nematodes suggests that the main selection for life history traits occurred independently in the major evolutionary branches.

254 citations


Journal ArticleDOI
TL;DR: The future challenge will be to elucidate the mechanisms of perception of avirulence factors and the subsequent signaling eventually leading to activation of host defense responses.
Abstract: Over the past 20 years, the interaction between the biotrophic fungal pathogen Cladosporium fulvum and tomato has developed into a versatile experimental system for molecular plant pathology and resistance breeding. This interaction provided the resources for cloning of fungal avirulence genes for the first time and interesting clues on recognition of their extracellular products by tomato, as well as mechanisms employed by the fungus to circumvent this recognition. A wealth of information has become available on the structure and genomic organization of Cf resistance genes. The occurrence of many clustered Cf homologues allows the generation of new genes with additional recognitional specificities by reshuffling. It is anticipated that potentially all proteins secreted by C. fulvum are recognized by one or more individuals in a population of tomato genotypes, a hypothesis that has been experimentally confirmed. The future challenge will be to elucidate the mechanisms of perception of avirulence factors and the subsequent signaling eventually leading to activation of host defense responses.

251 citations


Journal ArticleDOI
TL;DR: Gene parity analysis of baculovirus genomes suggests that SeM NPV and LdMNPV have a recent common ancestor and that they are more distantly related to the group I bacULoviruses AcMNPVs, BmNPV and OpMNPv.
Abstract: The nucleotide sequence of the DNA genome of Spodoptera exigua multicapsid nucleopoly- hedrovirus (SeMNPV), a group II NPV, was determined and analysed. The genome contains 135611 bp and has a GMC content of 44 mol%. Computer-assisted analysis revealed 139 ORFs of 150 nucleotides or larger; 103 have homologues in Autographa californica MNPV (AcMNPV) and a further 16 have homologues in other baculoviruses. Twenty ORFs are unique to SeMNPV. Major differences in SeMNPV gene content and arrangement were found compared with the group I NPVs AcMNPV, Bombyx mori (Bm) NPV and Orgyia pseudotsugata (Op) MNPV and the group II NPV Lymantria dispar (Ld) MNPV. Eighty-five ORFs were conserved among all five baculoviruses and are considered as candidate core baculovirus genes. Two putative p26 and odv-e66 homologues were identified in SeMNPV, each of which appeared to have been acquired independently and not by gene duplication. The SeMNPV genome lacks homologues of the major budded virus glycoprotein gene gp64, the immediate-early transactivator ie-2 and bro (baculovirus repeat ORF) genes that are found in AcMNPV, BmNPV, OpMNPV and LdMNPV. Gene parity analysis of baculovirus genomes suggests that SeMNPV and LdMNPV have a recent common ancestor and that they are more distantly related to the group I baculoviruses AcMNPV, BmNPV and OpMNPV. The orientation of the SeMNPV genome is reversed compared with the genomes of AcMNPV, BmNPV, OpMNPV and LdMNPV. However, the gene order in the 'central' part of baculovirus genomes is highly conserved and appears to be a key feature in the alignment of baculovirus genomes.

Journal ArticleDOI
TL;DR: In this article, a dynamic, regional-scale, land use change model is presented, defining the spatial distribution of these land use changes, based on multi-scale modelling of the relations between land use and socioeconomic and biophysical determinants.
Abstract: A long history of increases in population pressure in Java has caused agricultural land use to expand and intensify. More recent land use changes caused the conversion of prime agricultural land into residential and industrial area. Results of a dynamic, regional-scale, land use change model are presented, defining the spatial distribution of these land use changes. The model is based on multi-scale modelling of the relations between land use and socio-economic and biophysical determinants. Historical validation showed that the model can adequately simulate the pattern of land use change. Future patterns of land use change between 1994 and 2010 are simulated assuming further urbanization. The results suggest that most intensive land use changes will occur in Java's lowland areas.

Journal ArticleDOI
TL;DR: These findings clearly point to two important characteristics determining polyphenol cytotoxicity, namely their ease of oxidation and their lipophilicity.

Journal ArticleDOI
TL;DR: A model is presented aimed at a financial analysis of a Classical Swine Fever outbreak in the Netherlands and results show that total financial consequences of the outbreak are US $2.3 billion.

Journal ArticleDOI
TL;DR: A consistent terminology based on a multicompartment model for assessment of dermal exposure is proposed that describes the transport of contaminant mass from the source of the hazardous substance to the surface of the skin.
Abstract: Dermal exposure, primarily to pesticides, has been measured for almost half a century. Compared with exposure by inhalation, limited progress has been made towards standardisation of methods of measurement and development of biologically relevant exposure measures. It is suggested that the absence of a consistent terminology and a theoretical model has been an important cause of this lack of progress. Therefore, a consistent terminology based on a multicompartment model for assessment of dermal exposure is proposed that describes the transport of contaminant mass from the source of the hazardous substance to the surface of the skin. Six compartments and two barriers together with eight mass transport processes are described. With the model structure, examples are given of what some existing methods actually measure and where there are limited, or no, methods for measuring the relevant mass in a compartment or transport of mass. The importance of measuring the concentration of contaminant and not mass per area in the skin contaminant layer is stressed, as it is the concentration difference between the skin contamination layer and the perfused tissue that drives uptake. Methods for measuring uptake are currently not available. Measurement of mass, concentration, and the transport processes must be based on a theoretical model. Standardisation of methods of measurement of dermal exposure is strongly recommended.

Journal ArticleDOI
TL;DR: Results suggest that, in female meiotic systems in which spindle formation is based on the action of multiple microtubule organizing centers, the chromosomes not only promote microtubules polymerization and organization but their attachment to opposite spindle poles acts to stabilize the forming spindle Poles.
Abstract: In mouse oocytes, the first meiotic spindle is formed through the action of multiple microtubule organizing centers rather than a pair of centrosomes. Although the chromosomes are thought to play a major role in organizing the meiotic spindle, it remains unclear how a stable bipolar spindle is established. We have studied the formation of the first meiotic spindle in murine oocytes from mice homozygous for a targeted disruption of the DNA mismatch repair gene, Mlh1. In the absence of the MLH1 protein meiotic recombination is dramatically reduced and, as a result, the vast majority of chromosomes are present as unpaired univalents at the first meiotic division. The orientation of these univalent chromosomes at prometaphase suggests that they are unable to establish stable bipolar spindle attachments, presumably due to the inability to differentiate functional kinetochore domains on individual sister chromatids. In the presence of this aberrant chromosome behavior a stable first meiotic spindle is not formed, the spindle poles continue to elongate, and the vast majority of cells never initiate anaphase. These results suggest that, in female meiotic systems in which spindle formation is based on the action of multiple microtubule organizing centers, the chromosomes not only promote microtubule polymerization and organization but their attachment to opposite spindle poles acts to stabilize the forming spindle poles.

Journal ArticleDOI
21 Sep 1999-Langmuir
TL;DR: In this article, dilute alkene solutions for the formation of alkene monolayers with 1-hexadecene on a hydrogen-terminated silicon(100) surface has been investigated for a variety of solvents.
Abstract: The possibility to use dilute alkene solutions for the formation of alkene monolayers with 1-hexadecene on a hydrogen-terminated silicon(100) surface has been investigated for a variety of solvents. The resulting monolayers were analyzed by water contact angles. Anisole, n-butylbenzene, and n-decane were found to be unsuitable solvents for monolayer preparation at all 1-hexadecene concentrations used. At high 1-hexadecene concentrations (25% and 10% (v/v)) well-ordered monolayers were formed in toluene, xylene (mixture of isomers), cumene, tert-butylbenzene, and mesitylene. Only with mesitylene are high-quality monolayers feasible even at significantly lower alkene concentrations (down to 2.5%), making this the solvent of choice. The newly described procedure reduces the amount of alkene needed to form well-ordered monolayers by a factor of 20−40 in comparison with the original procedure that requires neat alkenes.

Journal ArticleDOI
TL;DR: In this article, the authors considered the simultaneous effects of bioconversion kinetics and metal transport in the medium coupled with metal complex dissociation kinetics for the two kinetically limiting situations of inert and fully labile complexes.
Abstract: The free-ion activity model for the biouptake of metals from complex media is limited to cases where mass transfer is not flux-determining. This paper considers the simultaneous effects of bioconversion kinetics and metal transport in the medium coupled with metal complex dissociation kinetics. For the two kinetically limiting situations of inert and fully labile complexes, the bioavailabilities of bioinactive metal complexes are analyzed under conditions where (i) the actual biouptake follows a Michaelis−Menten type of steady-state flux and (ii) the supply of free metal is governed by diffusion of free metal or coupled diffusion of the different labile metal species. The resulting steady-state fluxes are given in terms of two fundamental quantities, i.e., the relative bioaffinity parameter (a) and the ratio between the limiting uptake flux and the limiting transport flux (b). For labile complexes, these variables are differentiated by a complexation parameter defined by the ratio between the free metal i...

Journal ArticleDOI
TL;DR: A social learning perspective is developed in terms of a normative and analytical framework and used to analyze two managed resource systems: Fishery management in Lake Aheme, Benin and water resources management in Gelderland, The Netherlands.
Abstract: This article presents a social learning perspective as a means to analyze and facilitate collective decision making and action in managed resource systems such as platforms. First, the social learning perspective is developed in terms of a normative and analytical framework. The normative framework entails three value principles, namely, systems thinking, experimentation, and communicative rationality. The analytical framework is built up around the following questions: who learns, what is learned, why it is learned, and how. Next, this perspective is used to analyze two managed resource systems: Fishery management in Lake Aheme, Benin and water resources management in Gelderland, The Netherlands. To assess platform performance in resource use negotiation, emerging lessons from the case studies are combined with propositions concerning membership of platforms, accessibility of platform meetings, skills and relations of platform members, realization of platforms, and third party facilitation of platform activities.

Journal ArticleDOI
TL;DR: In this large case-control study, there is no evidence of association with risk of myocardial infarction of omega-3 fatty acids in adipose tissue, and the protective effect of alpha-linolenic acid was attenuated after adjusting for classical risk factors, but it deserves further research.
Abstract: Omega-3 fatty acids have potential antiatherogenic, antithrombotic, and antiarrhythmic properties, but their role in coronary heart disease remains controversial. To evaluate the association of omega-3 fatty acids in adipose tissue with the risk of myocardial infarction in men, a case-control study was conducted in eight European countries and Israel. Cases (n=639) included patients with a first myocardial infarction admitted to coronary care units within 24 hours from the onset of symptoms. Controls (n=700) were selected to represent the populations originating the cases. Adipose tissue levels of fatty acids were determined by capillary gas chromatography. The mean (±SD) proportion of α-linolenic acid was 0.77% (±0.19) of fatty acids in cases and 0.80% (±0.19) of fatty acids in controls (P=0.01). The relative risk for the highest quintile of α-linolenic acid compared with the lowest was 0.42 (95% confidence interval [CI] 0.22 to 0.81, P-trend=0.02). After adjusting for classical risk factors, the relative risk for the highest quintile was 0.68 (95% CI 0.31 to 1.49, P-trend=0.38). The mean proportion of docosahexaenoic acid was 0.24% (±0.13) of fatty acids in cases and 0.25% (±0.13) of fatty acids in controls (P=0.14), with no evidence of association with risk of myocardial infarction. In this large case-control study we could not detect a protective effect of docosahexaenoic acid on the risk of myocardial infarction. The protective effect of α-linolenic acid was attenuated after adjusting for classical risk factors (mainly smoking), but it deserves further research.

Journal ArticleDOI
TL;DR: In this article, the authors studied the feasibility of heavy metal extraction from activated sludge plants and found that heavy metals can be extracted for 60-70% and Zn for 90-100% by citric acid at pH 3-4.

Journal ArticleDOI
TL;DR: A detailed description of various mechanisms for the photocatalytic oxidation of alcohols and organochlorides in an aerated or a deaerated system is given in this article.

Journal ArticleDOI
TL;DR: This first biochemical and molecular characterization of a chlorophenol reductive dehalogenase has revealed structural resemblance with haloalkene reductiveDehalogenases.

Journal ArticleDOI
TL;DR: expression studies in different carotenogenic E. coli strains demonstrated that the crtYB gene encodes a bifunctional protein involved both in synthesis of phytoene from geranylgeranyl diphosphate and in cyclisation of lycopene to β-carotene.
Abstract: The red heterobasidiomycetous yeast Xanthophyllomyces dendrorhous (perfect state of Phaffia rhodozyma) contains a novel type of carotenoid biosynthetic enzyme. Its structural gene, designated crtYB, was isolated by functional complementation in a genetically modified, carotenogenic Escherichia coli strain. Expression studies in different carotenogenic E. coli strains demonstrated that the crtYB gene encodes a bifunctional protein involved both in synthesis of phytoene from geranylgeranyl diphosphate and in cyclisation of lycopene to β-carotene. By sequence comparison with other phytoene synthases and complementation studies in E. coli with various deletion derivatives of the crtYB gene, the regions responsible for phytoene synthesis and lycopene cyclisation were localised within the protein.

Journal ArticleDOI
TL;DR: Results show that Rhodococcus erythropolis DCL14 metabolizes both enantiomers of Limonene via a novel degradation pathway that starts with epoxidation at the 1,2 double bond forming limonene-1,2-epoxide.
Abstract: Strain DCL14, which is able to grow on limonene as a sole source of carbon and energy, was isolated from a freshwater sediment sample. This organism was identified as a strain of Rhodococcus erythropolis by chemotaxonomic and genetic studies. R. erythropolis DCL14 also assimilated the terpenes limonene-1,2-epoxide, limonene-1,2-diol, carveol, carvone, and (−)-menthol, while perillyl alcohol was not utilized as a carbon and energy source. Induction tests with cells grown on limonene revealed that the oxygen consumption rates with limonene-1,2-epoxide, limonene-1,2-diol, 1-hydroxy-2-oxolimonene, and carveol were high. Limonene-induced cells of R. erythropolis DCL14 contained the following four novel enzymatic activities involved in the limonene degradation pathway of this microorganism: a flavin adenine dinucleotide- and NADH-dependent limonene 1,2-monooxygenase activity, a cofactor-independent limonene-1,2-epoxide hydrolase activity, a dichlorophenolindophenol-dependent limonene-1,2-diol dehydrogenase activity, and an NADPH-dependent 1-hydroxy-2-oxolimonene 1,2-monooxygenase activity. Product accumulation studies showed that (1S,2S,4R)-limonene-1,2-diol, (1S,4R)-1-hydroxy-2-oxolimonene, and (3R)-3-isopropenyl-6-oxoheptanoate were intermediates in the (4R)-limonene degradation pathway. The opposite enantiomers [(1R,2R,4S)-limonene-1,2-diol, (1R,4S)-1-hydroxy-2-oxolimonene, and (3S)-3-isopropenyl-6-oxoheptanoate] were found in the (4S)-limonene degradation pathway, while accumulation of (1R,2S,4S)-limonene-1,2-diol from (4S)-limonene was also observed. These results show that R. erythropolis DCL14 metabolizes both enantiomers of limonene via a novel degradation pathway that starts with epoxidation at the 1,2 double bond forming limonene-1,2-epoxide. This epoxide is subsequently converted to limonene-1,2-diol, 1-hydroxy-2-oxolimonene, and 7-hydroxy-4-isopropenyl-7-methyl-2-oxo-oxepanone. This lactone spontaneously rearranges to form 3-isopropenyl-6-oxoheptanoate. In the presence of coenzyme A and ATP this acid is converted further, and this finding, together with the high levels of isocitrate lyase activity in extracts of limonene-grown cells, suggests that further degradation takes place via the β-oxidation pathway.

Journal ArticleDOI
TL;DR: In this article, an expanded-bed reactor was developed in order to stimulate the aggregation of the sulphur particles into large, well-settleable sulphur flocs with a diameter of about 3mm.

Journal ArticleDOI
TL;DR: In this article, the photocatalytic oxidations of methanol, ethanol and chloroform, trichloroethylene (TCE), and dichloropropionic acid (DCP) in M/TiO2 aqueous slurries are studied.

Journal ArticleDOI
01 Dec 1999
TL;DR: The IR spectra of the adsorbed proteins on the hydrophobic silica surface can not be interpreted, probably because of a large contribution to the IR signal of water molecules that are exchanged against the proteins during adsorption.
Abstract: Thesecondary structure of adsorbed immunoglobulin G (IgG) on different silica surfaces (hydrophilic, hydrophobic, hydrophobic with preadsorbed triblock-copolymers consisting of a polypropylene oxide buoy and two polyethylene oxide chains dangling in the solution) is studied by ATR-FTIR. Some results for adsorbed bovine serum albumin (BSA) are also presented. The secondary structure of adsorbed IgG was quantified using second-derivative spectra for the input parameters of the curve-fitting analysis of the original spectra. The secondary structure of adsorbed IgG on a hydrophilic silica surface resembles that of IgG in solution (about 60% beta-sheet and almost no alpha-helix content). There is some loss in the helix content of BSA after adsorption on the hydrophilic surface, but this structural element is still the most important one in the adsorbed protein. The IR spectra of the adsorbed proteins on the hydrophobic silica surface can not be interpreted, probably because of a large contribution to the IR signal of water molecules that are exchanged against the proteins during adsorption. The presence of preadsorbed triblock-copolymers reduces the adsorbed amount and causes an effect on the adsorbed proteins similar to that exerted by ethylene glycol: a different type of beta-sheet structure in IgG and a more ordered alpha-helix structure in BSA are provoked. Copyright 1999 Academic Press.

Journal ArticleDOI
TL;DR: Nitrate utilisation rate (NUR) batch tests with wastewater and acetate as carbon sources were carried out to extract process kinetics and the relation between the obtainable denitrification rate and the anoxic sludge loading rate can be used to design the rate of dosage of acetate.

Journal ArticleDOI
TL;DR: This paper presents a new construct of the yellow-cameleon-2, a probabilistic model for orbiculares that mimics the behaviour of the orbiculateleon and is able to identify the “spatially aggregating cells” of the animal.