Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    The Genetic Architecture of Post-Zygotic Reproductive Isolation Between Anopheles coluzzii and An. quadriannulatus
    Deitz, Kevin C. ; Takken, Willem ; Slotman, Michel A. - \ 2020
    Frontiers in Genetics Livestock Genomics 11 (2020). - ISSN 1664-8021
    Anopheles gambiae complex - Dobzhansky–Muller incompatibilities - hybrid - inviability - post-zygotic reproductive isolation - speciation - sterility

    The Anopheles gambiae complex is comprised of eight morphologically indistinguishable species and has emerged as a model system for the study of speciation genetics due to the rapid radiation of its member species over the past two million years. Male hybrids between most An. gambiae complex species pairs are sterile, and some genotype combinations in hybrid males cause inviability. We investigated the genetic basis of hybrid male inviability and sterility between An. coluzzii and An. quadriannulatus by measuring segregation distortion and performing a QTL analysis of sterility in a backcross population. Hybrid males were inviable if they inherited the An. coluzzii X chromosome and were homozygous at one or more loci in 18.9 Mb region of chromosome 3. The An. coluzzii X chromosome has a disproportionately large effect on hybrid sterility when introgressed into an An. quadriannulatus genetic background. Additionally, an epistatic interaction between the An. coluzzii X and a 1.12 Mb, pericentric region of the An. quadriannulatus 3L chromosome arm has a statistically significant contribution to the hybrid sterility phenotype. This same epistatic interaction occurs when the An. coluzzii X is introgressed into the genetic background of An. arabiensis, the sister species of An. quadriannulatus, suggesting that this may represent one of the first Dobzhansky–Muller incompatibilities to evolve early in the radiation of the Anopheles gambiae species complex. We describe the additive effects of each sterility QTL, epistatic interactions between them, and genes within QTL with protein functions related to mating behavior, reproduction, spermatogenesis, and microtubule morphogenesis, whose divergence may contribute to post-zygotic reproductive isolation between An. coluzzii and An. quadriannulatus.

    Multi-bucket optimization for integrated planning and scheduling in the perishable dairy supply chain
    Sel, C. ; Bilgen, B. ; Bloemhof, J.M. ; Vorst, J.G.A.J. van der - \ 2015
    Computers and Chemical Engineering 77 (2015). - ISSN 0098-1354 - p. 59 - 73.
    sequence-dependent changeovers - semicontinuous food-industries - yogurt production line - timed automata models - mixed-integer - batch plants - parallel machines - hybrid - algorithm - challenges
    This paper considers a dairy industry problem on integrated planning and scheduling of set yoghurt production. A mixed integer linear programming formulation is introduced to integrate tactical and operational decisions and a heuristic approach is proposed to decompose time buckets of the decisions. The decomposition heuristic improves computational efficiency by solving big bucket planning and small bucket scheduling problems. Further, mixed integer linear programming and constraint programming methodologies are combined with the algorithm to show their complementary strengths. Numerical studies using illustrative data with high demand granularity (i.e., a large number of small-sized customer orders) demonstrate that the proposed decomposition heuristic has consistent results minimizing the total cost (i.e., on average 8.75% gap with the best lower bound value found by MILP) and, the developed hybrid approach is capable of solving real sized instances within a reasonable amount of time (i.e., on average 92% faster than MILP in CPU time).
    Companies contributing to the greening of consumption: findings from the dairy and appliance industries in Thailand
    Thongplew, N. ; Koppen, C.S.A. van; Spaargaren, G. - \ 2014
    Journal of Cleaner Production 75 (2014). - ISSN 0959-6526 - p. 96 - 105.
    sustainable consumption - supply chain - responsibility - hybrid - world - foods - asia
    Over the last decades, the scope of corporate environmental strategies has shifted from improving internal environmental performance to reducing environmental footprint of the product chain in collaboration with actors in the chain. Consumer-oriented CSR strategies are a vital part of this trend but have received little scholarly attention, particularly in low- and middle-income countries. Focusing on Thailand, this article shows how corporate strategies aimed at greening consumption have become visible because of an increase in sustainable products, environmental information flows, and green narratives and images. We investigated two illustrative cases, dairy and appliance industries, and found that their environmental performances in greening consumption diverge. In the dairy industry, green products and environmental product information are mainly found among small producers for niche markets. Larger producers have only recently started adopting consumer-oriented environmental strategies. Appliance companies offer consumers not only green products, but also environmental information, storylines, and images reflecting general sustainability topics and, to a modest extent, consumer eco-lifestyles. We discuss underlying factors and argue that environmental communication strategies directed at consumers have strategic relevance for both industries.
    Signals of speciation within Arabidopsis thaliana in comparison with its relatives
    Alcazar, R. ; Pecinka, A. ; Aarts, M.G.M. ; Fransz, P.F. ; Koornneef, M. - \ 2012
    Current Opinion in Plant Biology 15 (2012)2. - ISSN 1369-5266 - p. 205 - 211.
    evolutionary history - natural variation - local adaptation - a-thaliana - self-incompatibility - genetic-basis - genome - lyrata - hybrid - plants
    The species within the now well-defined Arabidopsis genus provide biological materials suitable to investigate speciation and the development of reproductive isolation barriers between related species. Even within the model species A. thaliana, genetic differentiation between populations due to environmental adaptation or demographic history can lead to cases where hybrids between accessions are non-viable. Experimental evidence supports the importance of genome duplications and genetic epistatic interactions in the occurrence of reproductive isolation. Other examples of adaptation to specific environments can be found in Arabidopsis relatives where hybridization and chromosome doubling lead to new amphidiploid species. Molecular signals of speciation found in the Arabidopsis genus should provide a better understanding of speciation processes in plants from a genetic, molecular and evolutionary perspective
    Genome constitution of Narcissus variety, 'Tete-a-Tete', analysed through GISH and NBS profiling
    Wu, H. ; Ramanna, M.S. ; Arens, P. ; Tuyl, J.M. van - \ 2011
    Euphytica 181 (2011)2. - ISSN 0014-2336 - p. 285 - 292.
    in-situ hybridization - homoeologous recombination - hybrid - origin - chromosomes - lilium - dna
    The Narcissus variety, ‘Tête-à-Tête’, has been the most popular variety since 1949, and a well known allotriploid (2n = 3x = 24 + B) of spontaneous origin. Because the identity of one of the parents of this variety was uncertain, the genome constitution of ‘Tête-à-Tête’ was investigated by using genomic in situ hybridization (GISH) and NBS profiling. Both of these techniques confirmed that two different species of Narcissus, viz., N. tazetta (2n = 2x = 20) and N. cyclamineus (2n = 2x = 14) are the parents. GISH clearly identified 10 chromosomes of N. tazetta and 14 chromosomes of N. cyclamineus, the former has contributed one and the latter has contributed two genomes. One B chromosome was identically labelled as those of N. cyclamineus indicating the affinity of the special chromosome to this species. Due to its male and female sterility ‘Tête-à-Tête’ is unsuitable as a parent for utilizing in further breeding, it might be possible to re-synthesize a ‘Tête-à-Tête’ like variety using the now known parents and the original pathway
    Metal nanoparticle - block copolymer composite assembly and disassembly
    Li, Z.H. ; Sai, H. ; Warren, S.C. ; Kamperman, M.M.G. ; Arora, H. ; Gruner, S.M. ; Wiesner, U. - \ 2009
    Chemistry of materials 21 (2009)23. - ISSN 0897-4756 - p. 5578 - 5584.
    separated diblock copolymers - mesoporous molecular-sieves - lyotropic liquid-crystals - gold nanoparticles - thiol monolayer - hybrid - silica - mesophases - location - mixtures
    Ligand-stabilized platinum nanoparticles (Pt NPs) were self-assembled with poly(isoprene-block-dimethylaminoethyl methacrylate) (PI-b-PDMAEMA) block copolymers to generate organic-inorganic hybrid materials. High loadings of NPs in hybrids were achieved through usage of N,N-di-(2-(allyloxy)ethyl)-N-3-mercaptopropyl-N-methylammonium chloride as the ligand, which provided high solubility of NPs in various solvents as well as high affinity to PDMAEMA. From NP synthesis, existence of subnanometer Pt NPs was confirmed by high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) images. Estimations of the Pt NP ligand headgroup density based on HAADF-STEM images and thermogravimetric analysis (TGA) data yielded results comparable to what has been found for alkanethiol self-assembled monolayers (SAMs) on flat Pt {111} surfaces. Changing the volume fraction of Pt NPs in block copolymer-NP composites yielded hybrids with spherical micellar, wormlike micellar, lamellar, and inverse hexagonal morphologies. Disassembly of hybrids with spherical, wormlike micellar, and lamellar morphologies generated isolated metal NP-based nanospheres, cylinders, and sheets, respectively. Results suggest the existence of powerful design criteria for the formation of metal-based nanostructures from designer blocked macromolecules.
    Bacteriological contamination, dirt, and cracks of eggshells in furnished cages and noncage systems for laying hens: An international on-farm comparison
    Reu, K. de; Rodenburg, T.B. ; Messens, W. ; Heyndrickx, M. ; Tuyttens, F. ; Sonck, B. ; Zoons, J. ; Herman, L. - \ 2009
    Poultry Science 88 (2009)11. - ISSN 0032-5791 - p. 2442 - 2448.
    housing systems - conventional cages - egg quality - health - performance - design - hybrid - layers - flora
    For laying hens, the effects of housing system on bacterial eggshell contamination and eggshell quality is almost exclusively studied in experimental hen houses. The aim of this study was to compare eggshell hygiene and quality under commercial conditions. Six flocks of laying hens in furnished cages and 7 flocks in noncage systems were visited when hens were about 60 wk of age. Farms from Belgium, the Netherlands, and Germany were included in the study. The following parameters were determined on eggs sampled at the egg belts: 1) bacterial eggshell contamination, as expressed by total count of aerobic bacteria and number of Enterobacteriaceae; 2) proportion of dirty eggs; and 3) proportion of cracked eggs and eggs with microcracks. Considerable within-flock differences were found in eggshell contamination with total count of aerobic bacteria, both for furnished cages (P 0.001, range 4.24 to 5.22 log cfu/eggshell) and noncage systems (P 0.001, range 4.35 to 5.51 log cfu/eggshell). On average, lower levels of contamination with total count of aerobic bacteria (4.75 vs. 4.98 log cfu/eggshell; P 0.001) were found on eggshells from furnished cages compared with noncage systems. Concerning Enterobacteriaceae, no significant difference in average eggshell contamination between both systems could be shown. The total percentage of cracked eggs was higher (P 0.01) in furnished cages (7.8%) compared with noncage systems (4.1%). This was, however, due to the high percentage of cracked eggs (24%) observed on one of the furnished cage farms. We conclude that bacteriological eggshell contamination and percentage of cracked eggs differed substantially between individual farms using the same housing system. This may also explain some discrepancies between the findings of the present study versus some findings of previous experimental studies or studies on a small number of farms. Although statistically significant, the average differences in bacteriological contamination of nest eggs between both housing systems have limited microbiological relevancy
    Treatment of strong domestic sewage in a 96 m3 UASB reactor operated at ambient temperatures: two-stage versus single-stage reactor
    Halalsheh, M.M.I. ; Sawajneh, Z. ; Zu'bi, M. ; Zeeman, G. ; Lier, J.B. van; Fayyad, M. ; Lettinga, G. - \ 2005
    Bioresource Technology 96 (2005)5. - ISSN 0960-8524 - p. 577 - 585.
    anaerobic treatment - waste-water - sludge - hybrid
    A 96 m(3) UASB reactor was operated for 2.5 years under different conditions to assess the feasibility of treating strong sewage (CODtot = 1531 mg/l) at ambient temperatures, with averages of 18 and 25 degreesC for winter and summer respectively. During the first year, the reactor was operated as a two-stage system at OLRs in the range of 3.6-5.0 kg COD/m(3) d for the first stage and 2.9-4.6 kg COD/m(3) d for the second stage. The results of the first stage showed average removals of 51% and 60% for CODtot and CODss respectively without significant effect of temperature. The second stage reactor was unstable. The temperature affected sludge stabilization. During the second year, the first stage was operated as a single-stage UASB reactor at half of the previous loading rates. The results showed an average removal efficiency of 62% for CODtot during summer, while it dropped to 51% during wintertime. However, the effluent suspended solids were stabilized with VSS/TSS ratio around 0.50 all over the year. The sludge in the single-stage reactor was well-stabilized and exerted an excellent settlability. During the last three months of research, sludge was discharged regularly from the single-stage UASB reactor. The results showed no significant improvement in the performance in terms of CODtot. Based on the results of the experiment, a single-stage UASB reactor operated at relatively long HRT is preferred above two-stage system at the Jordanian conditions. (C) 2004 Elsevier Ltd. All rights reserved.
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