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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    From environmental nuisance to environmental opportunity: housefly larvae convert waste to livestock feed
    Zanten, H.H.E. van; Mollenhorst, H. ; Oonincx, D.G.A.B. ; Bikker, P. ; Meerburg, B.G. ; Boer, I.J.M. de - \ 2015
    Journal of Cleaner Production 102 (2015). - ISSN 0959-6526 - p. 362 - 369.
    life-cycle perspective - bio-energy - food - consequences - variability - digestion - scenarios - amazon - manure - land
    The livestock sector is in urgent need for more sustainable feed sources, because of the increased demand for animal-source food and the already high environmental costs associated with it. Recent developments indicate environmental benefits of rearing insects for livestock feed, suggesting that insect-based feed might become an important alternative feed source in the coming years. So far, however, this potential environmental benefit of waste-fed insects is unknown. This study, therefore, explores the environmental impact of using larvae of the common housefly grown on poultry manure and food waste as livestock feed. Data were provided by a laboratory plant in the Netherlands aiming to design an industrial plant for rearing housefly larvae. Production of 1 ton dry matter of larvae meal directly resulted in a global warming potential of 770 kg CO2 equivalents, an energy use of 9329 MJ and a land use of 32 m2, caused by use of water, electricity, and feed for flies, eggs and larvae. Production of larvae meal, however, also has indirect environmental consequences. Food waste, for example, was originally used for production of bio-energy. Accounting for these indirect consequences implies, e.g., including the environmental impact of production of energy needed to replace the original bio-energy function of food waste. Assuming, furthermore, that 1 ton of larvae meal replaced 0.5 ton of fishmeal and 0.5 ton of soybean meal, the production of 1 ton larvae meal reduced land use (1713 m2), but increased energy use (21,342 MJ) and consequently global warming potential (1959 kg CO2-eq). Results of this study will enhance a transparent societal and political debate about future options and limitations of larvae meal as livestock feed. Results of the indirect environmental impact, however, are situation specific, e.g. in this study food waste was used for anaerobic digestion. In case food waste would have been used for, e.g., composting, the energy use and related emission of greenhouse gases might decrease. Furthermore, the industrial process to acquire housefly larvae meal is still advancing, which also offers potential to reduce energy use and related emissions. Eventually, land scarcity will increase further, whereas opportunities exist to reduce energy use by, e.g., technical innovations or an increased use of solar or wind energy. Larvae meal production, therefore, has potential to reduce the environmental impact of the livestock sector.
    Loss of animal seed dispersal increases extinction risk in a tropical tree species due to pervasive negative density dependence across life stages
    Caughlin, T.T. ; Ferguson, J.M. ; Lichstein, J.W. ; Zuidema, P.A. ; Bunyavejchewin, S. ; Levey, D.J. - \ 2015
    Proceedings of the Royal Society. B: Biological Sciences 282 (2015)1798. - ISSN 0962-8452 - 9 p.
    spatial-patterns - rain-forest - recruitment - consequences - neighborhood - defaunation - habitat - uncertainty - diversity - abundance
    Overhunting in tropical forests reduces populations of vertebrate seed dispersers. If reduced seed dispersal has a negative impact on tree population viability, overhunting could lead to altered forest structure and dynamics, including decreased biodiversity. However, empirical data showing decreased animal-dispersed tree abundance in overhunted forests contradict demographic models which predict minimal sensitivity of tree population growth rate to early life stages. One resolution to this discrepancy is that seed dispersal determines spatial aggregation, which could have demographic consequences for all life stages. We tested the impact of dispersal loss on population viability of a tropical tree species, Miliusa horsfieldii, currently dispersed by an intact community of large mammals in a Thai forest. We evaluated the effect of spatial aggregation for all tree life stages, from seeds to adult trees, and constructed simulation models to compare population viability with and without animal-mediated seed dispersal. In simulated populations, disperser loss increased spatial aggregation by fourfold, leading to increased negative density dependence across the life cycle and a 10-fold increase in the probability of extinction. Given that the majority of tree species in tropical forests are animal-dispersed, overhunting will potentially result in forests that are fundamentally different from those existing now.
    Influence of separate feeding of calcium on nutrient digestibility, energy utilisation and performance of young broilers fed pelleted wheat-based diets
    Abdollahi, M.R. ; Dalen, A.B.J. van; Hendriks, W.H. ; Ravindran, V. - \ 2015
    Animal Feed Science and Technology 205 (2015). - ISSN 0377-8401 - p. 122 - 130.
    phytate phosphorus hydrolysis - nonphytate phosphorus - phytic acid - chickens - ph - efficacy - appetite - availability - consequences - ingredients
    Six broiler starter diets, based on wheat and soybean meal, were formulated to contain 1.1 2.0, 4.0, 6.0, 8.0 and 10.0 g calcium (Ca)/kg. All diets were equivalent in respect of total and non-phytate phosphorus contents (5.4 and 3.0 g/kg, respectively). The influence of dietary treatments on the growth performance, coefficient of apparent ileal digestibility (CAID) of nitrogen (N), starch, fat and phosphorus (P), Ca retention and apparent metabolisable energy (AME) in broiler starters was evaluated. A total of 288, one-day-old male broilers (Ross 308) were allocated to 36 cages (8 birds/cage), and cages were randomly assigned to 6 dietary treatments. Birds were also provided with a source of Ca in a separate feed trough. Birds fed the diet with 1.1 g Ca/kg gained more (P0.05) feed per unit gain. During d 8 to 14, d 15 to 21, and over the entire trial period of 21 d, birds fed Ca-deficient (6.0 g Ca/kg and less) diets consumed more (P0.05) of dietary Ca on the retention of Ca and ash, AME and toe ash. The present data suggest that feeding broilers low Ca diets with access to a separate Ca source, is advantageous in terms of broiler performance, while maintaining bone mineralisation. The data also demonstrate that the provision of separate Ca source may hold promise for reducing the dietary P contents.
    Drought stress affects plant metabolites and herbivore preference but not host location by its parasitoids
    Weldegergis, B.T. ; Zhu, F. ; Poelman, E.H. ; Dicke, M. - \ 2015
    Oecologia 177 (2015)3. - ISSN 0029-8549 - p. 701 - 713.
    volatile emissions - water-stress - abiotic factors - oviposition - genes - biosynthesis - consequences - lepidoptera - complexity - expression
    One of the main abiotic stresses that strongly affects plant survival and the primary cause of crop loss around the world is drought. Drought stress leads to sequential morphological, physiological, biochemical and molecular changes that can have severe effects on plant growth, development and productivity. As a consequence of these changes, the interaction between plants and insects can be altered. Using cultivated Brassica oleracea plants, the parasitoid Microplitis mediator and its herbivorous host Mamestra brassicae, we studied the effect of drought stress on (1) the emission of plant volatile organic compounds (VOCs), (2) plant hormone titres, (3) preference and performance of the herbivore, and (4) preference of the parasitoid. Higher levels of jasmonic acid (JA) and abscisic acid (ABA) were recorded in response to herbivory, but no significant differences were observed for salicylic acid (SA) and indole-3-acetic acid (IAA). Drought significantly impacted SA level and showed a significant interactive effect with herbivory for IAA levels. A total of 55 VOCs were recorded and the difference among the treatments was influenced largely by herbivory, where the emission rate of fatty acid-derived volatiles, nitriles and (E)-4,8-dimethylnona-1,3,7-triene [(E)-DMNT] was enhanced. Mamestra brassicae moths preferred to lay eggs on drought-stressed over control plants; their offspring performed similarly on plants of both treatments. VOCs due to drought did not affect the choice of M. mediator parasitoids. Overall, our study reveals an influence of drought on plant chemistry and insect-plant interactions.
    How to assess species richness along single environmental gradients? Implications of potential versus realized species distributions
    Goethem, T.M.W.J. van; Huijbregts, M.A.J. ; Wamelink, G.W.W. ; Schipper, A.M. - \ 2015
    Environmental Pollution 200 (2015). - ISSN 0269-7491 - p. 120 - 125.
    sensitivity distributions - field data - plant - diversity - abundance - macroinvertebrates - acidification - consequences - biodiversity - assemblages
    Quantifying relationships between species richness and single environmental factors is challenging as species richness typically depends on multiple environmental factors. Recently, various methods have been proposed to tackle this challenge. Using a dataset comprising field observations of grassland vegetation and measured pH values, we compared three methods for deriving species richness response curves. One of the methods estimates species richness close to the maximum species richness observed at the sites, whereas the other two provide estimates of the potential species richness along the environmental gradient. Our response curves suggest that potential species richness of grasslands is slightly more sensitive to acidification than realized plant species richness. However, differences in corresponding environmental quality standards (EQS) for acidification were small compared to intrinsic spatial differences in natural soil pH, indicating that natural background values are more important to consider in the derivation of EQS for pH than methodological differences between the three approaches.
    Survival, reproduction, and immigration explain the dynamics of a local Red-backed Shrike population in the Netherlands
    Hemerik, L. ; Geertsma, M. ; Waasdorp, S. ; Middelveld, R.P. ; Kleef, H. van; Klok, T.C. - \ 2015
    Journal of Ornithology 156 (2015)1. - ISSN 2193-7192 - p. 35 - 46.
    lanius-collurio - marked animals - birds - consequences - dispersal - patterns - weather
    Populations of many bird species strongly declined in Western Europe in the late twentieth century. One such species is the Red-backed Shrike in the Netherlands. In one of the last strongholds of this species, the Bargerveen Reserve, the breeding population flourished in the 1990s due to rewetting management. However, further development of the area has led to a decline in breeding numbers such that the population is now less than half the size it was in the 1990s. Here, we analyze the vital rates of the Red-backed Shrike population in the Bargerveen. In 2001–2008, nestlings in this population were individually marked, and resighting data was collected during the breeding seasons of 2002–2009. We used estimates of vital rates based on monitoring in 2001 until 2009 to diagnose the population dynamics. Mark–recapture data were analyzed with the program MARK. The most parsimonious model gave age- and gender-specific survival probabilities of 0.12 for first-year females, 0.64 for older females, 0.20 for first-year males, and 0.54 for older males (with overlapping confidence intervals for the gender-specific adult survival values). The estimated yearly resighting probabilities were gender specific, with a higher probability observed for males (0.81) than for females (0.53). For 2001–2009, we computed an average number of offspring per breeding pair of 2.91 (with 72 % of the pairs breeding successfully). Using these vital rates, we parameterized a simple matrix model. The resulting yearly growth was 0.80. Adult survival had an elasticity of 0.83, while juvenile survival and reproduction both had an elasticity of 0.20. Because the population numbers have stabilized since 2005, the observed yearly population growth suggests that 20 % of the Red-backed Shrikes breeding in the Bargerveen are immigrants. Comparison with data on other Red-backed Shrike populations indicates that juvenile and adult survival rates can be improved in the Bargerveen Reserve. Appropriate management measures to accomplish this are discussed.
    It's my party and I eat if I want to. Reasons for unhealthy snacking
    Verhoeven, A.A.C. ; Adriaanse, M.A. ; Vet, E. de; Fennis, B.M. ; Ridder, D.T.D. de - \ 2015
    Appetite 84 (2015). - ISSN 0195-6663 - p. 20 - 27.
    implementation intentions - self-regulation - food-intake - behavior - questionnaire - consequences - adolescents - overweight - habit - plans
    Investigating the reasons that people give for unhealthy snacking behavior is important for developing effective health interventions. Little research, however, has identified reasons that apply to a large audience and most studies do not integrate multiple factors, precluding any conclusions regarding their relative importance. The present study explored reasons for unhealthy snacking among a representative community sample. Participants (N¿=¿1544) filled out the newly developed Reasons to Snack inventory assessing an elaborate range of motives at baseline and 1-month follow-up. Exploratory and replication factor analyses identified six categories: opportunity induced eating, coping with negative emotions, enjoying a special occasion, rewarding oneself, social pressure, and gaining energy. The highest mean scores were obtained for enjoying a special occasion and opportunity induced eating. Regression analyses with participant characteristics as independent variables and each category of reasons as dependent variables showed differences for age. For all reasons except to enjoy a special occasion, younger people reported a higher score. Women indicated a higher score than men on coping with negative emotions, enjoying a special occasion and gaining energy. People who diet to a stronger extent reported a higher score for snacking because of social pressure, to reward oneself and to cope with negative emotions, with the latter also being related to a higher BMI. Finally, a higher education was associated with enjoying a special occasion. Future health interventions could allocate more attention to diminishing unhealthy snacking with regard to the six identified categories, specifically focusing on enjoying a special occasion and opportunity induced eating.
    Small Homologous Blocks in Phytophthora Genomes Do Not Point to an Ancient Whole-Genome Duplication
    Hooff, J.J.E. van; Snel, B. ; Seidl, M.F. - \ 2014
    Genome Biology and Evolution 6 (2014)5. - ISSN 1759-6653 - p. 1079 - 1085.
    pathogen phytophthora - maximum-likelihood - evolution - genes - consequences - mechanisms - adaptation - repertoire - sequences - infestans
    Genomes of the plant-pathogenic genus Phytophthora are characterized by small duplicated blocks consisting of two consecutive genes (2HOM blocks) and by an elevated abundance of similarly aged gene duplicates. Both properties, in particular the presence of 2HOM blocks, have been attributed to a whole-genome duplication (WGD) at the last common ancestor of Phytophthora. However, large intraspecies synteny-compelling evidence for a WGD-has not been detected. Here, we revisited the WGD hypothesis by deducing the age of 2HOM blocks. Two independent timing methods reveal that the majority of 2HOM blocks arose after divergence of the Phytophthora lineages. In addition, a large proportion of the 2HOM block copies colocalize on the same scaffold. Therefore, the presence of 2HOM blocks does not support a WGD at the last common ancestor of Phytophthora. Thus, genome evolution of Phytophthora is likely driven by alternative mechanisms, such as bursts of transposon activity.
    Natural disasters and economic growth: A meta-analysis
    Klomp, J.G. ; Valckx, K. - \ 2014
    Global environmental change : human and policy dimensions 26 (2014). - ISSN 0959-3780 - p. 183 - 195.
    climate-change - civil conflict - consequences - impacts - matter - bias
    Using more than 750 estimates, we perform a meta-regression analysis of studies examining the relationship between economic growth per capita and natural disasters. The studies considered are very different with respect to the type of disasters considered, the sample of countries and time periods covered, model specification, estimators used and publication outlet. After extensive testing of our results, we conclude that there exists a negative genuine effect of natural disasters on economic growth which is increasing over the period of our analysis. Still, the magnitude differs across disasters included and country sample used. In particular, it turns out that climatic disasters in developing countries have the most significant adverse impact on economic growth. However, we also find some evidence that a part of the negative impact of natural disasters found in these studies is caused by a publication bias. (C) 2014 Elsevier Ltd. All rights reserved.
    Farming systems in two less favoured areas in portugal: their development from 1989 to 2009 and the implications for sustainable land management
    Jones, N.M. ; Graaff, J. de; Duarte, F. ; Rodrigo, I. ; Poortinga, A. - \ 2014
    Land Degradation and Development 25 (2014)1. - ISSN 1085-3278 - p. 29 - 44.
    agricultural soil conservation - policy measures - european-union - consequences - degradation - typology - spain - ndvi
    Since the late 1980s, sustainable land management is one of the objectives of the European Commission in Less Favoured Areas. In this paper, we investigate the economic and environmental sustainability of farming systems in two less favoured areas in Centro and Alentejo areas of Portugal. The specific objectives were the following: (i) to characterise the farming systems; (ii) to analyse their development over a 20-year period (1989-2009); and (iii) to investigate to what extent these farming systems contribute to sustainable land management. The diversity of the farming systems was identified through a survey and cluster analysis and compared with the Farm Accountancy Data Network classification on types of farming. Indicators on the economic and environmental sustainability were estimated, namely, farm net income, return to labour and rotation management, on the basis of a survey, Farm Accountancy Data Network database and Landsat imagery, respectively. Results indicate an increased focus on livestock in the past 20years (1989-2009). In Centro, rotation management was not affected. The small ruminant farms have been able to retain a positive farm net income but that was only possible with a below average return to labour. In Alentejo, the increased focus on livestock, cattle in particular, led to an intensification of fodder production on certain plots. Mixed crop-livestock farms show a negative farm net income since 1995 and depend heavily on subsidies to remain viable. As other studies in southern Europe have shown, farm strategies have often been directed towards lowering labour inputs, lowering forage deficits through on-farm produced resources and acquiring subsidies. Copyright (c) 2013 John Wiley & Sons, Ltd.
    Economics of eradicating Foot-and-Mouth disease epidemics with alternative control strategies
    Bergevoet, R.H.M. ; Asseldonk, M.A.P.M. van - \ 2014
    Archivos de Medicina Veterinaria 46 (2014)3. - ISSN 0301-732X - p. 381 - 388.
    vaccination - consequences - model
    The paper presents an economic analysis of Foot-and-Mouth Disease (FMD) control strategies for livestock herds. Alternative vaccination-to-live control strategies were compared to the strategy that involves culling of all susceptible animals in an area of 1 km around infected herds in addition to standard measures as culling of infected herds, pre-emptive slaughter of contact herds, establishment of control and surveillance zones. Vaccination strategies differed with respect to the radius of vaccination around infected farms (2 km versus 5 km). As an example to illustrate the economic consequences the Netherlands was used. These strategies were evaluated for a Sparsely Populated Livestock Areas (SPLA) with less than 2 farms/km2 and a Densely Populated Livestock Areas (DPLA) with more than 4 farms/km2. Results of the partial budgeting FMD model revealed that for DPLA a control strategy which includes a vaccination radius of 2 km is most cost effective. For SPLA a control strategy which includes a 1 km culling radius around an infected farm is most cost effective.
    Genetic variability of central–western European pine marten (Martes martes) populations
    Pertoldi, C. ; Elschot, K. ; Ruiz-Gonzalez, A. ; Zande, L. van de; Zalewski, A. ; Muñoz, J. ; Madsen, A.B. ; Loeschcke, V. ; Groot, G.A. de; Bijlsma, R.J. - \ 2014
    Acta Theriologica 59 (2014)4. - ISSN 0001-7051 - p. 503 - 510.
    mitochondrial-dna variation - glacial refugia - clethrionomys-glareolus - control-region - phylogeography - conservation - consequences - colonization - evolution - patterns
    Recent studies highlighted the potential role of cryptic glacial refugia for temperate taxa in Europe beyond the Mediterranean peninsulas. To further investigate phylogeographic features of the European pine marten (Martes martes) in previously identified cryptic refugia located in central–western Europe, we analysed the hyper-variable diagnostic fragment of the mitochondrial control region in a total of 134 specimens, allowing for reliable comparisons with previous genetic studies of the species. We included samples from eight different European countries in central–western Europe (Belgium, France, Luxembourg and the Netherlands), in south–western Europe (Spain), in north–central Europe (Denmark) and in central Europe (Germany and Poland). The sequences collapsed in 17 haplotypes, which allowed us to determine the genetic composition of the pine marten populations throughout central–western Europe. Overall, our results showed that the population genetic variation, estimated by the standardised haplotype diversity, was high (0.400¿=¿Hs¿=¿0.762), and it was considerably higher in Germany (0.762) and the Netherlands (0.722) compared to the other countries. The nucleotide diversity was relatively low (0.002¿=¿p¿=¿0.016) even in Germany and the Netherlands (0.016 and 0.014, respectively), suggesting relatively small, long-term effective population sizes or severe bottlenecks. Out of the 17 haplotypes found in our study area, 13 were unique and limited to a single country: one in Denmark, one in Spain, four in Poland and seven in the Netherlands. The pairwise genetic distance ranged from 0.001 to 0.032 and did not show any evident correlation with the geographic distances between the populations. A genealogical relationship network was constructed, which provided evidence for a recent origin of many of the unique haplotypes. Approximately 82 % of the samples analysed in this study belonged to haplotypes grouped into a previously identified central–northern European phylogroup of the species. Our results support previous findings, indicating low contribution of southern refugial populations to the postglacial recolonization of central–western Europe and a predominant contribution of pine marten populations that survived the Last Glacial Maxima in cryptic northern refugia.
    Effects of CO2 enrichment on cockle shell growth interpreted with a Dynamic Energy Budget model
    Klok, T.C. ; Wijsman, J.W.M. ; Kaag, N.H.B.M. ; Foekema, E.M. - \ 2014
    Journal of Sea Research 94 (2014). - ISSN 1385-1101 - p. 111 - 116.
    early-life stages - ocean acidification - elevated-temperature - cerastoderma-edule - population-level - mytilus-edulis - exposure - impact - consequences - reproduction
    The increase in human induced atmospheric CO2 level leads to an increase in ocean acidification (OA). Mitigation of this increase by storage of CO2 in abandoned marine oil and gas reservoirs is seen as an interesting cost effective solution. However, this involves a risk of CO2 loss causing localised reductions in seawater pH. In this paper we report on the effects of CO2 enhancement on the growth of the bivalve Cerastoderma edule in mesocosms. The experiments show significant reductions in shell length, shell weight and cockle flesh dry weight at increased CO2 level suggesting both direct (shell erosion) and indirect (metabolic) effects. Indirect effects were analysed and interpreted using a Dynamic Energy Budget model by describing changes in 3 metabolic processes: assimilation, maintenance, and growth. Based on cockle size data only we could not differentiate between these processes, however, by using variability of DEB parameter values in 11 bivalve species, we showed growth to be the least relevant process.
    Over-expression of Arabidopsis AtCHR23 chromatin remodeling ATPase results in increased variability of growth and gene expression
    Folta, A. ; Severing, E.I. ; Krauskopf, J. ; Geest, H.C. van de; Verver, J. ; Nap, J.P.H. ; Mlynarova, L. - \ 2014
    BMC Plant Biology 14 (2014). - ISSN 1471-2229 - 18 p.
    rna-seq - seed-germination - stress responses - root-growth - thaliana - plant - pickle - noise - identification - consequences
    Background Plants are sessile organisms that deal with their -sometimes adverse- environment in well-regulated ways. Chromatin remodeling involving SWI/SNF2-type ATPases is thought to be an important epigenetic mechanism for the regulation of gene expression in different developmental programs and for integrating these programs with the response to environmental signals. In this study, we report on the role of chromatin remodeling in Arabidopsis with respect to the variability of growth and gene expression in relationship to environmental conditions. Results Already modest (2-fold) over-expression of the AtCHR23 ATPase gene in Arabidopsis results in overall reduced growth compared to the wild-type. Detailed analyses show that in the root, the reduction of growth is due to reduced cell elongation. The reduced-growth phenotype requires sufficient light and is magnified by applying deliberate abiotic (salt, osmotic) stress. In contrast, the knockout mutation of AtCHR23 does not lead to such visible phenotypic effects. In addition, we show that over-expression of AtCHR23 increases the variability of growth in populations of genetically identical plants. These data indicate that accurate and controlled expression of AtCHR23 contributes to the stability or robustness of growth. Detailed RNAseq analyses demonstrate that upon AtCHR23 over-expression also the variation of gene expression is increased in a subset of genes that associate with environmental stress. The larger variation of gene expression is confirmed in individual plants with the help of independent qRT-PCR analysis. Conclusions Over-expression of AtCHR23 gives Arabidopsis a phenotype that is markedly different from the growth arrest phenotype observed upon over-expression of AtCHR12, the paralog of AtCHR23, in response to abiotic stress. This demonstrates functional sub-specialization of highly similar ATPases in Arabidopsis. Over-expression of AtCHR23 increases the variability of growth among genetically identical individuals in a way that is consistent with increased variability of expression of a distinct subset of genes that associate with environmental stress. We propose that ATCHR23-mediated chromatin remodeling is a potential component of a buffer system in plants that protects against environmentally-induced phenotypic and transcriptional variation.
    Your health our concern, our health whose concern? : perceptions of injustice in organizational relationships and processes and frontline health worker motivation in Ghana
    Aberese-Ako, M. ; Dijk, H. van; Gerrits, T. ; Arhinful, D.K. ; Agyepong, I.A. - \ 2014
    Health Policy and Planning 29 (2014)suppl.2. - ISSN 0268-1080 - p. ii15 - ii28.
    quality-of-care - interactional justice - intrinsic motivation - developing-countries - procedural justice - public-sector - consequences - satisfaction - performance - framework
    Taking a perspective of frontline health workers as internal clients within health systems, this study explored how perceived injustice in policy and organizational matters influence frontline health worker motivation and the consequent effect on workers’ attitudes and performance in delivering maternal and neonatal health care in public hospitals. It consisted of an ethnographic study in two public hospitals in Southern Ghana. Participant observation, conversation and in-depth interviews were conducted over a 16-month period. Ethical approval and consent were obtained from relevant persons and authorities. Qualitative analysis software Nvivo 8 was used for coding and analysis of data. Main themes identified in the analysis form the basis for interpreting and reporting study findings. Findings showed that most workers perceived injustice in distributive, procedural and interactional dimensions at various levels in the health system. At the national policy level this included poor conditions of service. At the hospital level, it included perceived inequity in distribution of incentives, lack of protection and respect for workers. These influenced frontline worker motivation negatively and sometimes led to poor response to client needs. However, intrinsically motivated workers overcame these challenges and responded positively to clients’ health care needs. It is important to recognize and conceptualize frontline workers in health systems as internal clients of the facilities and organizations within which they work. Their quality needs must be adequately met if they are to be highly motivated and supported to provide quality and responsive care to their clients. Meeting these quality needs of internal clients and creating a sense of fairness in governance arrangements between frontline workers, facilities and health system managers is crucial. Consequently, intervention measures such as creating more open door policies, involving frontline workers in decision making, recognizing their needs and challenges and working together to address them are critical.
    The presence of a below-ground neighbour alters within-plant seed size distribution in Phaseolus vulgaris
    Chen, B. ; During, H.J. ; Vermeulen, P.J. ; Anten, N.P.R. - \ 2014
    Annals of Botany 114 (2014). - ISSN 0305-7364 - p. 937 - 943.
    root competition - variable environments - optimal balance - number - recognition - germination - growth - consequences - adaptation - plasticity
    * Background and Aims Considerable variation in seed size commonly exists within plants, and is believed to be favoured under natural selection. This study aims to examine the extent to which seed size distribution depends on the presence of competing neighbour plants. * Methods Phaseolus vulgaris plants rooting with or without a conspecific neighbourwere grown in soil with high or low nutrient availability. Seeds were harvested at the end of the growth cycle, the total nitrogen and phosphorus invested in seed production were measured and within-plant seed size distribution was quantified using a set of statistical descriptors. * Key Results Exposure to neighbours’ roots induced significant changes in seed size distribution. Plants produced proportionally more large seeds and fewer small ones, as reflected by significant increases in minimal seed size, mean seed size, skewness and Lorenz asymmetry coefficient. These effects were different from, and in several cases opposite to, the responses when the soil nutrient level was reduced, and were significant after correction for the amount of resources invested in seed production. * Conclusions Below-ground neighbour presence affects within-plant seed size distribution in P. vulgaris. This effect appears to be non-resource-mediated, i.e. to be independent of neighbour-induced effects on resource availability. It implies that, based on current environmental cues, plants can make an anticipatory adjustment of their investment strategy in offspring as an adaptation to the local environment in the future. Key words: Anticipatory maternal effect, bet-hedging, game theory, neighbour detection, Phaseolus vulgaris, kidney bean, root competition, seed-setting, seed size variation, size inequality, skewness. INTRODUCTION A considerable degree of variation in seed size within plants is commonly observed (Michaels et al., 1988; Silvertown, 1989; Ruiz de Clavijo, 2002; Vo¨ller et al., 2012). Such variation is often interpreted as an adaptive bet-hedging strategy (Harper et al., 1970; McGinley et al., 1987; McGinley and Charnov, 1988; Venable and Brown, 1988; Geritz, 1995). Many studies also reveal that plants modify the pattern of variation (i.e. distribution) to cope with their abiotic environmental conditions (e.g. temperature, Wulff, 1986; light, Galloway, 2001; nutrients, Galloway, 2001;water, Parciak, 2002). Herewe demonstrate that seed size distribution may also be modified in response to the presence of a below-ground neighbour. Within a species, seed size (following common practice, seed size refers to seedweight in this paper) often correlates positively with the competitiveness of the offspring (e.g. Houssard and Escarre´, 1991; Eriksson, 1999; Lehtila¨ and Ehrle´n, 2005; Dubois and Cheptou, 2012). Based on the trade-off, induced by resource limitation in plants, between competition (favours large seeds) and colonization (favours a large number of small seeds), Geritz (1995) extended an optimal offspring size model (Smith and Fretwell, 1974) by considering seedling competition and using
    Overweight increases risk of trimester hypothyroxinaemia in iodine-deficient pregnant woman
    Gowachirapant, S. ; Boonstra, A. ; Winichagoon, P. ; Zimmerman, M.B. - \ 2014
    Maternal and Child Nutrition 10 (2014)1. - ISSN 1740-8695 - p. 61 - 71.
    maternal hypothyroxinemia - thyroid-disease - free-thyroxine - hypothyroidism - obesity - supplementation - consequences - population - prevalence - management
    Hypothyroxinaemia early in pregnancy may impair fetal brain development. Increased body weight has been associated with low thyroxine concentrations in non-pregnant women. In pregnant women, morbid maternal obesity is a risk factor for thyroid dysfunction. But whether lesser degrees of overweight that are much more common could be a risk factor for hypothyroxinaemia in pregnancy is unclear. The objective of this study was to investigate if overweight increases risk for thyroid dysfunction, and specifically hypothyroxinaemia, in iodine-deficient pregnant women. We performed a cross-sectional study at first hospital visit among healthy Thai pregnant women. We measured weight and height, urinary iodine concentration (UIC), serum thyroid hormones and thyroglobulin. Pre-pregnancy weight and relevant dietary factors were determined by questionnaire, and body mass index (BMI) was used to classify weight status. Among 514 women (mean gestational age, 11 weeks) with a median UIC of 111¿µg¿dL–1, indicating mild iodine deficiency, 12% had low free thyroxine (fT4) concentrations: 3% had overt hypothyroidism; 7% had subclinical hypothyroidism; and 8% had isolated hypothyroxinaemia. Based on pre-pregnancy BMI, 26% of women were overweight or obese. In a multiple regression model, BMI was a negative predictor of fT4 (ß¿=¿-0.20, P¿
    Negative density dependence of seed dispersal and seedling recruitment in a Neotropical palm
    Jansen, P.A. ; Visser, M.D. ; Joseph Wright, S. ; Rutten, G. ; Muller-Landau, H.C. - \ 2014
    Ecology Letters 17 (2014)9. - ISSN 1461-023X - p. 1111 - 1120.
    scatter-hoarding rodent - tropical tree - spatial-patterns - plant diversity - forest - competition - removal - consequences - mechanisms - herbivores
    Negative density dependence (NDD) of recruitment is pervasive in tropical tree species. We tested the hypotheses that seed dispersal is NDD, due to intraspecific competition for dispersers, and that this contributes to NDD of recruitment. We compared dispersal in the palm Attalea butyracea across a wide range of population density on Barro Colorado Island in Panama and assessed its consequences for seed distributions. We found that frugivore visitation, seed removal and dispersal distance all declined with population density of A. butyracea, demonstrating NDD of seed dispersal due to competition for dispersers. Furthermore, as population density increased, the distances of seeds from the nearest adult decreased, conspecific seed crowding increased and seedling recruitment success decreased, all patterns expected under poorer dispersal. Unexpectedly, however, our analyses showed that NDD of dispersal did not contribute substantially to these changes in the quality of the seed distribution; patterns with population density were dominated by effects due solely to increasing adult and seed density.
    Heterosis is prevalent among domesticated but not wild strains of Saccharomyces cerevisiae
    Plech, M. ; Visser, J.A.G.M. de; Korona, R. - \ 2014
    G3 : Genes Genomes Genetics 4 (2014). - ISSN 2160-1836 - p. 315 - 323.
    history trade-offs - inbreeding depression - deleterious mutations - outbreeding depression - population genomics - yeast - evolution - load - consequences - accumulation
    Crosses between inbred but unrelated individuals often result in an increased fitness of the progeny. This phenomenon is known as heterosis and has been reported for wild and domesticated populations of plants and animals. Analysis of heterosis is often hindered by the fact that the genetic relatedness between analyzed organisms is only approximately known. We studied a collection of Saccharomyces cerevisiae isolates from wild and human-created habitats whose genomes were sequenced and thus their relatedness was fully known. We reasoned that if these strains accumulated different deleterious mutations at an approximately constant rate, then heterosis should be most visible in F1 heterozygotes from the least related parents. We found that heterosis was substantial and positively correlated with sequence divergence, but only in domesticated strains. More than 80% of the heterozygous hybrids were more fit than expected from the mean of their homozygous parents, and approximately three-quarters of those exceeded even the fittest parent. Our results support the notion that domestication brings about relaxation of selection and accumulation of deleterious mutations. However, other factors may have contributed as well. In particular, the observed build-up of genetic load might be facilitated by a decrease, and not increase, in the rate of inbreeding
    Conflict and the Evolution of Institutions: Unbundling Institutions at the Local Level in Burundi
    Voors, M.J. ; Bulte, E.H. - \ 2014
    Journal of Peace Research 51 (2014)4. - ISSN 0022-3433 - p. 455 - 469.
    civil-war - violent conflict - armed conflict - consequences - rwanda - uganda - land - africa - health
    The impact of armed conflict may persist long after the end of war, and may include a lasting institutional legacy. We use a novel dataset from rural Burundi to examine the impact of local exposure to conflict on institutional quality, and try to ‘unbundle’ institutions by distinguishing between three dimensions of the institutional framework: property rights security, local political institutions, and social capital. We find that conflict exposure affects institutional quality, and document that the impact of conflict on institutional quality may be positive or negative, depending on the institutional measure. Specifically, exposure to violence strengthens in-group social capital and promotes tenure security. However, the appreciation for state institutions is negatively affected by exposure to violence. We find no evidence consistent with design-based theories of institutional quality, or the idea that institutional quality is enhanced by interventions of (non)state external actors. Instead our findings provide some support for the theory of parochial altruism. Our results emphasize the importance for policymakers to consider autonomous responses to conflict when designing development programs. They further imply some caution for actors seeking to reform local institutions through top-down interventions.
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