Staff Publications

Staff Publications

  • external user (warningwarning)
  • Log in as
  • language uk
  • About

    '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.

    We have a manual that explains all the features 

Records 1 - 20 / 27

  • help
  • print

    Print search results

  • export

    Export search results

  • alert
    We will mail you new results for this query: q=Stephens
Check title to add to marked list
Making sense of making meat: key moments in the first 20 years of tissue engineering muscle to make food.
Stephens, Neil ; Sexton, Alexandra E. ; Driessen, C.P.G. - \ 2019
Frontiers in Sustainable Food Systems 3 (2019). - ISSN 2571-581X
Cultured/clean/cell-based meat (CM) now has a near two decade history of laboratory research, commencing with the early NASA-funded work at Touro College and the bioarts practice of the Tissue Culture and Art project. Across this period the field, or as it is now more commonly termed, the “space,” has developed significantly while promoting different visions for what CM is and can do, and the best mechanisms for delivery. Here we both analyse and critically engage with this near-twenty year period as a productive provocation to those engaged with CM, or considering becoming so. This paper is not a history of the field, and does not offer a comprehensive timeline. Instead it identifies significant activities, transitions, and moments in which key meanings and practices have taken form or exerted influence. We do this through analyzing two related themes: the CM “institutional context” and the CM “interpretative package.” The former, the institutional context, refers to events and infrastructures that have come into being to support and shape the CM field, including university activities, conferences, third sector groups, various potential funding mechanisms, and the establishment of a start-up sector. The latter, the interpretative package, refers to the constellation of factors that shape or assert how CM should be understood, including the various names used to describe it, accounts of what it will achieve, and most recently, the emergent regulatory discussions that frame its legal standing. Across the paper we argue it is productive to think of the CM community in terms of a first and second wave. The first wave was more university-based and broadly covers the period from the millennium until around the 2013 cultured burger event. The second wave saw the increasing prevalence of a start-up culture and the circuits of venture capital interest that support it. Through this analysis we seek to provoke further reflection upon how the CM community has come to be as it is, and how this could develop in the future
Global atmospheric CO2 inverse models converging on neutral tropical land exchange, but disagreeing on fossil fuel and atmospheric growth rate
Gaubert, Benjamin ; Stephens, Britton B. ; Basu, Sourish ; Chevallier, Frédéric ; Deng, Feng ; Kort, Eric A. ; Patra, Prabir K. ; Peters, Wouter ; Rödenbeck, Christian ; Saeki, Tazu ; Schimel, David ; Laan-Luijkx, Ingrid van der; Wofsy, Steven ; Yin, Yi - \ 2019
Biogeosciences 16 (2019)1. - ISSN 1726-4170 - p. 117 - 134.

We have compared a suite of recent global CO2 atmospheric inversion results to independent airborne observations and to each other, to assess their dependence on differences in northern extratropical (NET) vertical transport and to identify some of the drivers of model spread. We evaluate posterior CO2 concentration profiles against observations from the High-Performance Instrumented Airborne Platform for Environmental Research (HIAPER) Pole-To-Pole Observations (HIPPO) aircraft campaigns over the mid-Pacific in 2009-2011. Although the models differ in inverse approaches, assimilated observations, prior fluxes, and transport models, their broad latitudinal separation of land fluxes has converged significantly since the Atmospheric Carbon Cycle Inversion Intercomparison (TransCom 3) and the REgional Carbon Cycle Assessment and Processes (RECCAP) projects, with model spread reduced by 80% since TransCom 3 and 70% since RECCAP. Most modeled CO2 fields agree reasonably well with the HIPPO observations, specifically for the annual mean vertical gradients in the Northern Hemisphere. Northern Hemisphere vertical mixing no longer appears to be a dominant driver of northern versus tropical (T) annual flux differences. Our newer suite of models still gives northern extratropical land uptake that is modest relative to previous estimates (Gurney et al., 2002; Peylin et al., 2013) and near-neutral tropical land uptake for 2009- 2011. Given estimates of emissions from deforestation, this implies a continued uptake in intact tropical forests that is strong relative to historical estimates (Gurney et al., 2002; Peylin et al., 2013). The results from these models for other time periods (2004-2014, 2001-2004, 1992-1996) and reevaluation of the TransCom 3 Level 2 and RECCAP results confirm that tropical land carbon fluxes including deforestation have been near neutral for several decades. However, models still have large disagreements on ocean-land partitioning. The fossil fuel (FF) and the atmospheric growth rate terms have been thought to be the best-known terms in the global carbon budget, but we show that they currently limit our ability to assess regional-scale terrestrial fluxes and ocean-land partitioning from the model ensemble.

Objectively measured physical activity and sedentary time are associated with cardiometabolic risk factors in adults with prediabetes : The PREVIEW study
Swindell, Nils ; Mackintosh, Kelly ; Mcnarry, Melitta ; Stephens, Jeffrey W. ; Sluik, Diewertje ; Fogelholm, Mikael ; Drummen, Mathijs ; Macdonald, Ian ; Martinez, J.A. ; Handjieva-Darlenska, Teodora ; Poppitt, Sally D. ; Brand-Miller, Jennie ; Larsen, Thomas M. ; Raben, Anne ; Stratton, Gareth - \ 2018
Diabetes Care 41 (2018)3. - ISSN 0149-5992 - p. 562 - 569.
OBJECTIVE The aim of the present cross-sectional study was to examine the association among physical activity (PA), sedentary time (ST), and cardiometabolic risk in adults with prediabetes. RESEARCH DESIGN AND METHODS Participants (n = 2,326; 25-70 years old, 67% female) from eight countries, with a BMI >25 kg · m22 and impaired fasting glucose (5.6-6.9 mmol · L21) or impaired glucose tolerance (7.8-11.0 mmol · L21 at 2 h), participated. Seven-day accelerometry objectively assessed PA levels and ST. RESULTS Multiple linear regression revealed that moderate-To-vigorous PA (MVPA) was negatively associated withHOMAof insulin resistance (HOMA-IR) (standardizedb =20.078 [95% CI20.128,20.027]), waist circumference (WC) (b =20.177 [20.122,20.134]), fasting insulin (b = 20.115 [20.158, 20.072]), 2-h glucose (b = 20.069 [20.112, 20.025]), triglycerides (b = 20.091 [20.138, 20.044]), and CRP (b = 20.086 [20.127, 20.045]). ST was positively associated with HOMA-IR (b = 0.175 [0.114, 0.236]), WC (b = 0.215 [0.026, 0.131]), fasting insulin (b = 0.155 [0.092, 0.219]), triglycerides (b = 0.106 [0.052, 0.16]), CRP (b = 0.106 [0.39, 0.172]), systolic blood pressure (BP) (b = 0.078 [0.026, 0.131]), and diastolic BP (b = 0.106 [0.39, 20.172]). Associations reported between total PA (counts · min21), and all risk factors were comparable or stronger than for MVPA: HOMA-IR (b = 20.151 [20.194, 20.107]), WC (b = 20.179 [20.224, 20.134]), fasting insulin (b = 20.139 [20.183, 20.096]), 2-h glucose (b = 20.088 [20.131, 20.045]), triglycerides (b = 20.117 [20.162, 20.071]), and CRP (b = 20.104 [20.146, 20.062]). CONCLUSIONS In adults with prediabetes, objectively measured PA and ST were associated with cardiometabolic risk markers. Total PA was at least as strongly associated with cardiometabolic risk markers as MVPA, which may imply that the accumulation of total PA over the day is as important as achieving the intensity of MVPA.
The impact of the US retreat from the Paris Agreement : Kyoto revisited?
Pickering, Jonathan ; McGee, Jeffrey S. ; Stephens, Tim ; Karlsson-Vinkhuyzen, Sylvia I. - \ 2018
Climate Policy 18 (2018)7. - ISSN 1469-3062 - p. 818 - 827.
Kyoto Protocol - Paris Agreement - treaty withdrawal - United States of America

The United States’ decision to withdraw from the Paris Agreement (pending possible re-engagement under different terms) may have significant ramifications for international climate policy, but the implications of this decision remain contested. This commentary illustrates how comparative analysis of US participation in multilateral environmental agreements can inform predictions and future assessments of the decision. We compare and contrast US non-participation in the Kyoto Protocol and the Paris Agreement, focusing on four key areas that may condition the influence of US treaty decisions on international climate policy: (i) global momentum on climate change mitigation; (ii) the possibility of US non-participation giving rise to alternative forms of international collaboration on climate policy; (iii) the timing and circumstances of the US decision to exit; and (iv) the influence of treaty design on countries’ incentives to participate and comply. We find that differences across the two treaties relating to the first three factors are more likely to reduce the negative ramifications of US withdrawal from the Paris Agreement compared to the Kyoto Protocol. However, the increased urgency of deep decarbonization renders US non-participation a major concern despite its declining share of global emissions. Moreover, key design features of the Paris Agreement suggest that other countries may react to the US decision by scaling back their levels of ambition and compliance, even if they remain in the Agreement. Key policy insightsIncreasing global momentum on mitigation since 1997 means that US withdrawal from the Paris Agreement is potentially less damaging than its non-participation in the Kyoto ProtocolDespite the declining US share of global emissions, greater urgency of deep decarbonization means that the non-participation of a major player, such as the US, remains problematic for global cooperation and achieving the Paris Agreement’s goalsDifferences in the design of the Kyoto Protocol and Paris Agreement suggest that US non-participation is more likely to prompt reluctant countries to stay within the Paris framework but reduce levels of ambition and compliance, rather than exit the Agreement altogether

Continental and global scale flood forecasting systems
Emerton, Rebecca E. ; Stephens, Elisabeth M. ; Pappenberger, Florian ; Pagano, Thomas P. ; Weerts, A.H. ; Wood, A. ; Salamon, Peter ; Brown, James D. ; Hjerdt, Niclas ; Donnelly, Chantal ; Baugh, Calum A. ; Cloke, Hannah L. - \ 2016
Wiley Interdisciplinary Reviews: Water 3 (2016)3. - ISSN 2049-1948 - p. 391 - 418.
Floods are the most frequent of natural disasters, affecting millions of people across the globe every year. The anticipation and forecasting of floods at the global scale is crucial to preparing for severe events and providing early awareness where local flood models and warning services may not exist. As numerical weather prediction models continue to improve, operational centers are increasingly using their meteorological output to drive hydrological models, creating hydrometeorological systems capable of forecasting river flow and flood events at much longer lead times than has previously been possible. Furthermore, developments in, for example, modelling capabilities, data, and resources in recent years have made it possible to produce global scale flood forecasting systems. In this paper, the current state of operational large-scale flood forecasting is discussed, including probabilistic forecasting of floods using ensemble prediction systems. Six state-of-the-art operational large-scale flood forecasting systems are reviewed, describing similarities and differences in their approaches to forecasting floods at the global and continental scale. Operational systems currently have the capability to produce coarse-scale discharge forecasts in the medium-range and disseminate forecasts and, in some cases, early warning products in real time across the globe, in support of national forecasting capabilities. With improvements in seasonal weather forecasting, future advances may include more seamless hydrological forecasting at the global scale alongside a move towards multi-model forecasts and grand ensemble techniques, responding to the requirement of developing multi-hazard early warning systems for disaster risk reduction. WIREs Water 2016, 3:391–418. doi: 10.1002/wat2.1137
Should the Lion Eat Straw Like the Ox? Animal Ethics and the Predation Problem
Keulartz, Jozef - \ 2016
Journal of Agricultural and Environmental Ethics (2016). - ISSN 1187-7863 - 22 p.
Capability approach - Political theory of animal rights - Predation problem - Rights theories - Utilitarianism

Stephen Clark’s article The Rights of Wild Things from 1979 was the starting point for the consideration in the animal ethics literature of the so-called ‘predation problem’. Clark examines the response of David George Ritchie to Henry Stephens Salt, the first writer who has argued explicitly in favor of animal rights. Ritchie attempts to demonstrate—via reductio ad absurdum—that animals cannot have rights, because granting them rights would oblige us to protect prey animals against predators that wrongly violate their rights. This article navigates the reader through the debate sparked off by Clarke’s article, with as final destination what I consider to be the best way to deal with the predation problem. I will successively discuss arguments against the predation reductio from Singer’s utilitarian approach, Regan’s deontological approach, Nussbaum’s capability approach, and Donadson and Kymlicka’s political theory of animal rights.

Opportunistically recorded acoustic data support Northeast Atlantic mackerel expansion theory
Kooij, Jeroen vander; Fassler, S.M.M. ; Stephens, D. ; Readdy, Lisa ; Scott, B. ; Roel, Beatriz - \ 2016
ICES Journal of Marine Science 73 (2016)4. - ISSN 1054-3139 - p. 1115 - 1126.
fisheries acoustics - mackerel - North sea - scomber scombrus
Fisheries independent monitoring of widely distributed pelagic fish species which conduct large seasonal migrations is logistically complex and expensive.One of the commercially most important examples of such a species in the Northeast Atlantic Ocean is mackerel for which up to recently only an international triennial egg survey contributed to the stock assessment. In this study, we explore whether fisheries acoustic data, recorded opportunistically during the English component of the North Sea International Bottom Trawl Survey, can contribute to an improved understanding of mackerel distribution and provide supplementary data to existing dedicated monitoring surveys. Using a previously published multifrequency acoustic mackerel detection algorithm, we extracted the distribution and abundance of schooling mackerel for the whole of the North Sea during August and September between 2007 and 2013. The spatio-temporal coverage of this unique dataset is of particular interest because it includes part of the unsurveyed summer mackerel feeding grounds in the northern North Sea. Recent increases in landings in Icelandic waters during this season suggested that changes have occurred in the mackerel feeding distribution. Thus far it is poorly understood whether these changes are due to a shift, i.e. mackerel moving away from their traditional feeding grounds in the northern North Sea and southern Norwegian Sea, or whether the species’
distribution has expanded. We therefore explored whether acoustically derived biomass of schooling mackerel declined in the northern North Sea during the study period, which would suggest a shift in mackerel distribution rather than an expansion. The results of this study show that in the North Sea, schooling mackerel abundance has increased and that its distribution in this area has not changed over this period. Both of these findings provide, to our knowledge, the first evidence in support of the hypothesis that mackerel have expanded their distribution rather than moved away.
A systematic review of studies evaluating Australian indigenous community development projects : The extent of community participation, their methodological quality and their outcomes Health behavior, health promotion and society
Snijder, Mieke ; Shakeshaft, Anthony ; Wagemakers, Annemarie ; Stephens, Anne ; Calabria, Bianca - \ 2015
BMC Public Health 15 (2015)1. - ISSN 1471-2458 - 16 p.
Aboriginal - Community development - Community participation - Empowerment - Health promotion - Indigenous - Methodological quality - Qualitative - Quantitative - Torres Strait Islander

Background: Community development is a health promotion approach identified as having great potential to improve Indigenous health, because of its potential for extensive community participation. There has been no systematic examination of the extent of community participation in community development projects and little analysis of their effectiveness. This systematic review aims to identify the extent of community participation in community development projects implemented in Australian Indigenous communities, critically appraise the qualitative and quantitative methods used in their evaluation, and summarise their outcomes. Methods: Ten electronic peer-reviewed databases and two electronic grey literature databases were searched for relevant studies published between 1990 and 2015. The level of community participation and the methodological quality of the qualitative and quantitative components of the studies were assessed against standardised criteria. Results: Thirty one evaluation studies of community development projects were identified. Community participation varied between different phases of project development, generally high during project implementation, but low during the evaluation phase. For the majority of studies, methodological quality was low and the methods were poorly described. Although positive qualitative or quantitative outcomes were reported in all studies, only two studies reported statistically significant outcomes. Discussion: Partnerships between researchers, community members and service providers have great potential to improve methodological quality and community participation when research skills and community knowledge are integrated to design, implement and evaluate community development projects. Conclusion: The methodological quality of studies evaluating Australian Indigenous community development projects is currently too weak to confidently determine the cost-effectiveness of community development projects in improving the health and wellbeing of Indigenous Australians. Higher quality studies evaluating community development projects would strengthen the evidence base.

Observational evidence for interhemispheric hydroxyl-radical parity
Patra, P.K. ; Krol, M.C. ; Montzka, S.A. ; Arnold, T. ; Atlas, E.L. ; Lintner, B.R. ; Stephens, B.B. ; Xiang, B. - \ 2014
Nature 513 (2014)7517. - ISSN 0028-0836 - p. 219 - 223.
atmospheric hydroxyl - sulfur-hexafluoride - methyl chloroform - tropospheric oh - model - variability - transport - chemistry - climate - methane
The hydroxyl radical (OH) is a key oxidant involved in the removal of air pollutants and greenhouse gases from the atmosphere1, 2, 3. The ratio of Northern Hemispheric to Southern Hemispheric (NH/SH) OH concentration is important for our understanding of emission estimates of atmospheric species such as nitrogen oxides and methane4, 5, 6. It remains poorly constrained, however, with a range of estimates from 0.85 to 1.4 (refs 4, 7,8,9,10). Here we determine the NH/SH ratio of OH with the help of methyl chloroform data (a proxy for OH concentrations) and an atmospheric transport model that accurately describes interhemispheric transport and modelled emissions. We find that for the years 2004–2011 the model predicts an annual mean NH–SH gradient of methyl chloroform that is a tight linear function of the modelled NH/SH ratio in annual mean OH. We estimate a NH/SH OH ratio of 0.97 ± 0.12 during this time period by optimizing global total emissions and mean OH abundance to fit methyl chloroform data from two surface-measurement networks and aircraft campaigns11, 12, 13. Our findings suggest that top-down emission estimates of reactive species such as nitrogen oxides in key emitting countries in the NH that are based on a NH/SH OH ratio larger than 1 may be overestimated.
Genome expansion and gene loss in powdery mildew fungi reveal tradeoffs in extreme parasitism
Spanu, P.D. ; Abbott, J.C. ; Amselem, J. ; Burgis, T.A. ; Soanes, D.M. ; Stüber, K. ; Loren van Themaat, E. Ver; Brown, J.K.M. ; Butcher, S.A. ; Gurr, S.J. ; Lebrun, M.H. ; Ridout, C.J. ; Schulze-Lefert, P. ; Talbot, N.J. ; Ahmadinejad, N. ; Ametz, C. ; Barton, G.R. ; Benjdia, M. ; Bidzinski, P. ; Bindschedler, L.V. ; Both, M. ; Brewer, M.T. ; Cadle-Davidson, L. ; Cadle-Davidson, M.M. ; Collemare, J. ; Cramer, R. ; Frenkel, O. ; Godfrey, D. ; Harriman, J. ; Hoede, C. ; King, B.C. ; Klages, S. ; Kleemann, J. ; Knoll, D. ; Koti, P.S. ; Kreplak, J. ; López-Ruiz, F.J. ; Lu, X. ; Maekawa, T. ; Mahanil, S. ; Micali, C. ; Milgroom, M.G. ; Montana, G. ; Noir, S. ; O'Connell, R.J. ; Oberhaensli, S. ; Parlange, F. ; Pedersen, C. ; Quesneville, H. ; Reinhardt, R. ; Rott, M. ; Sacristán, S. ; Schmidt, S.M. ; Schön, M. ; Skamnioti, P. ; Sommer, H. ; Stephens, A. ; Takahara, H. ; Thordal-Christensen, H. ; Vigouroux, M. ; Weßling, R. ; Wicker, T. ; Panstruga, R. - \ 2010
Science 330 (2010)6010. - ISSN 0036-8075 - p. 1543 - 1546.
plant-pathogens - virulence - proteins
Powdery mildews are phytopathogens whose growth and reproduction are entirely dependent on living plant cells. The molecular basis of this life-style, obligate biotrophy, remains unknown. We present the genome analysis of barley powdery mildew, Blumeria graminis f.sp. hordei (Blumeria), as well as a comparison with the analysis of two powdery mildews pathogenic on dicotyledonous plants. These genomes display massive retrotransposon proliferation, genome-size expansion, and gene losses. The missing genes encode enzymes of primary and secondary metabolism, carbohydrate-active enzymes, and transporters, probably reflecting their redundancy in an exclusively biotrophic life-style. Among the 248 candidate effectors of pathogenesis identified in the Blumeria genome, very few (less than 10) define a core set conserved in all three mildews, suggesting that most effectors represent species-specific adaptations.
Improved wheat yield and production forecasting with a moisture stress index, AVHRR and MODIS data
Schut, A.G.T. ; Stephens, D.J. ; Stovold, R.G.H. ; Adams, M. ; Craig, R.L. - \ 2009
Crop and Pasture Science 60 (2009)1. - ISSN 1836-0947 - p. 60 - 70.
difference vegetation index - crop yield - time-series - satellite imagery - winter-wheat - ndvi data - model - prediction - nitrogen - calibration
The objective of this study was to improve the current wheat yield and production forecasting system for Western Australia on a LGA basis. PLS regression models including temporal NDVI data from AVHRR and/or MODIS, CR, and/or SI, calculated with the STIN, were developed. Census and survey wheat yield data from the Australian Bureau of Statistics were combined with questionnaire data to construct a full time-series for the years 1991–2005. The accuracy of fortnightly in-season forecasts was evaluated with a leave-year-out procedure from Week 32 onwards. The best model had a mean relative prediction error per LGA (RE) of 10% for yield and 15% for production, compared with RE of 13% for yield and 18% for production for the model based on SI only. For yield there was a decrease in RMSE from below 0.5 t/ha to below 0.3 t/ha in all years. The best multivariate model also had the added feature of being more robust than the model based on SI only, especially in drought years. In-season forecasts were accurate (RE of 10–12% and 15–18% for yield and production, respectively) from Week 34 onwards. Models including AVHRR and MODIS NDVI had comparable errors, providing means for predictions based on MODIS. It is concluded that the multivariate model is a major improvement over the current DAFWA wheat yield forecasting system, providing for accurate in-season wheat yield and production forecasts from the end of August onwards.
Sampling of food: useful tool or lucky shot?
Dijkhoff-Jongenburger, I. - \ 2009
In: Abstracts of lectures and posters Rapid Methods Europe 2009, 26-28 January 2009, Noordwijkerhout, Netherlands. - - p. 37 - 37.
Introduction Low numbers of Cronobacter sakazakii (Enterobacter sakazakii), an organism that has caused serious disease in newborn and premature babies, can contaminate powdered infant formula. Consumers and industry share the same interest to detect such contamination and to guarantee a safe product. In the ‘European Regulations on microbiological criteria for foodstuffs’, sampling plans have been enshrined to detect C. sakazakii in powdered infant formula. In order to discuss these sampling plans, the International Commission on Microbiological Specification for Foods has made the following assumption (ICMSF, 2002): the pathogens in batches of powdered infant formula are log-normally distributed, i.e. the log of the concentration is normally distributed, with 0.8 log cfu/g as the standard deviation (s). The aim of this study is to test the validity of the assumption and to the determine the impact on the sampling plans in case the assumption does not match with reality. To begin, the assumption of a normal distribution can be countered. In theory the log counts of pathogens are normally distributed in the batch of milk powder with a mean concentration and a standard deviation. However, local contamination or local microbial growth or survival can cause a different spatial distribution. Consequently, it is likely that contaminants show various distributions in foods (Habraken et al., 1986). Furthermore, the chosen standard of 0.8 log cfu/g is based on data derived from the meat industry and no evidence exist to suggest that it applies to other commodities as well. Objective This study aims to describe various spatial microbial distributions in powdered infant formula mathematically and to analyse them statistically. Methods We have investigated artificially contaminated powdered infant formula at a small scale. In our experiments, we distributed the contamination homogeneously and heterogeneously. First, powdered infant formula was inoculated with Cronobacter sakazakii ATCC 29544. Then five grams of this contaminated powder was added to 1 kilogram of un-inoculated powder in two ways: not mixed or thoroughly mixed. This resulted in a more heterogeneous or homogeneous spatial distribution. The spatial distributions were determined by taking 144 samples of 0.5 gram from each kilogram. C. sakazakii was plate counted on Trypton Soy Agar (TSA). The detection limit was 50 cfu/gram. The resulting distributions were fitted with GenStat 9th edition. Results The numbers detected in the 144 samples are displayed as the cumulative empirical distribution function (EDF). Several statistical distributions were fitted to these EDF data. The Anderson-Darling statistic (Stephens, 1974) showed that the Weibull and the Normal distributions fitted the three homogenous batches (p >0.05). The three heterogeneous batches could not be fitted by any distribution. To consider the contaminated part only, the Weibull distribution was accepted in two cases (p > 0.05) and the Normal distribution was accepted once (p > 0.05). Conclusions Thoroughly mixed batch: the Normal and the Weibull distributions could describe the log counts of C. sakazakii in the milk powder. Not mixed batch: No known statistical distribution could describe the log counts. However, in some cases the Weibull and the Normal distributions could describe the contaminated part. References ICMSF (2002) International Commission on Microbiological Specifications for Foods. Micro organisms in foods 7. Microbiological testing in food safety management. New York: Kluwer Academic/Plenum Publishers. Habraken, C.J.M., Mossel, D.A.A., and van den Reek, S. (1986). Management of Salmonella risks in the production of powdered milk products. Neth. Milk Dairy J. 40, 99-116. Stephens, M.A. 1974 EDF Statistics for goodness of fit and some comparisons. Journal of American Statistical Association, Vol. 69, no. 347, pp. 730-737.
Weak northern and strong tropical land carbon uptake from vertical profiles of atmospheric CO2
Stephens, B.B. ; Gurney, K.R. ; Tans, P.P. ; Sweeney, C. ; Peters, W. - \ 2007
Science 316 (2007)5832. - ISSN 0036-8075 - p. 1732 - 1735.
long-term - terrestrial biosphere - forest ecosystems - plant-growth - transport - sink - sequestration - inversions - emissions - dioxide
Measurements of midday vertical atmospheric CO2 distributions reveal annual-mean vertical CO2 gradients that are inconsistent with atmospheric models that estimate a large transfer of terrestrial carbon from tropical to northern latitudes. The three models that most closely reproduce the observed annual-mean vertical CO2 gradients estimate weaker northern uptake of ¿1.5 petagrams of carbon per year (Pg C year¿1) and weaker tropical emission of +0.1 Pg C year¿1 compared with previous consensus estimates of ¿2.4 and +1.8 Pg C year¿1, respectively. This suggests that northern terrestrial uptake of industrial CO2 emissions plays a smaller role than previously thought and that, after subtracting land-use emissions, tropical ecosystems may currently be strong sinks for CO2.
Judge Nelson Timothy Stephens lecture: the EU regulatory approach to GM foods
Meulen, B.M.J. van der - \ 2007
Kansas Journal of Law & Public Policy 14 (2007)3. - ISSN 1055-8942 - p. 286 - 323.
Mixed Conifer Forest Duff Consumption during Prescribed Fires: Tree Crown Impacts
Hille, M.G. ; Stephens, S.L. - \ 2005
Forest Science 51 (2005)5. - ISSN 0015-749X - p. 417 - 424.
sierra-nevada - spatial-patterns - plot-scale - soil - pine - growth - throughfall - combustion - severity - moisture
Fire suppression has produced large forest floor fuel loads in many coniferous forests in western North America. This study describes spatial patterns of duff consumption in a mixed-conifer forest in the north-central Sierra Nevada, California. Overstory crown coverage was correlated to spatial patterns of duff depth after prescribed fire. On one site that was burned under dry conditions, almost all duff was consumed, with some remaining in overstory gaps. On a second site that was burned under moist conditions a few days after the first annual precipitation, strong spatial patterns of duff consumption were recorded with increasing distance from the base of the nearest overstory tree, the probability of duff remaining after prescribed fire increased significantly. There is strong evidence that spatial variation of precipitation throughfall resulted in higher duff moisture in gaps, whereas duff beneath crown cover was drier, and therefore, totally consumed. This study demonstrates that including a spatial component in a process-based duff consumption model would improve the accuracy of fire-effect predictions.
The distribution of chydorids (Branchiopoda, Anomopoda)in European shallow lakes and its application to ecological quality monitoring
Eyto, E. de; Irvine, K. ; Garcia-Criado, F. ; Gyllström, M. ; Jeppesen, E. ; Kornijow, R. ; Miracle, M.R. ; Nykänen, M. ; Bareiss, C. ; Cerbin, S. ; Salujoe, J. ; Franken, R.J.M. ; Stephens, D. ; Moss, B. - \ 2003
Archiv für Hydrobiologie 156 (2003)2. - ISSN 0003-9136 - p. 181 - 202.
waterkwaliteit - meren - branchiopoda - biologische indicatoren - temperatuur - sediment - eutrofiëring - ecologie - europa - nederland - water quality - lakes - branchiopoda - biological indicators - temperature - sediment - eutrophication - ecology - europe - netherlands - trophic state - cladoceran remains - water chemistry - assemblages - reconstruction - zooplankton - sediments - microcrustacea
This study describes the chydorid (Branchiopoda, Anomopoda) assemblages from 66 European shallow lakes, and presents data relating the assemblages to lake type and ecological quality
This study describes the chydorid (Branchiopoda, Anomopoda) assemblages from 66 European shallow lakes, and presents data relating the assemblages to lake type and ecological quality. Forty species, out of a total recorded European fauna of 60 species, were found in the study sites. No significant differences were found between chydorid assemblages associated with rock and plant substrata. Patterns of distribution were best explained primarily by latitude and pH. Chlorophyll-a, total phosphorus, water temperature and Secchi depth were also correlated with assemblage descriptors. Alonopsis elongata, Alona rectangula, Alonella excisa and Pleuroxus uncinatus were shown to have higher prevalence in certain lake types. The dominance of Chydorus sphaericus in a third of the study sites was linked to eutrophication and high levels of chlorophyll-a. The relationship between chydorids and lake ecological quality was more apparent at species rather than community level. This study identifies important typological factors affecting chydorid distribution, and confirms that patterns of chydorid distribution previously reported from regional studies hold true across Europe.
Description of larvae of Herophydrus musicus (Klug) and analysis of relationships with members of the genus Hygrotus Stephens (Coleoptera: Dytiscidae, Hydroporinae)
Alarie, Y. ; Cuppen, J.G.M. ; Hendrich, L. ; Nilsson, A.N. - \ 2001
Aquatic Insects 23 (2001)3. - ISSN 0165-0424 - p. 193 - 207.
Description of the larvae of Herophydrus musicus (Klug, 1833) is presented including a detailed chaetotaxic and porotaxic analysis of the cephalic capsule, head appendages, legs, last abdominal segment and urogomphi. Compared to other genera of the tribe Hydroporini, it is postulated that Herophydrus Sharp is more closely related to members of the genus Hygrotus s. lat. Stephens based on the following synapomorphies: (i) absence of the primary pore ANf; (ii) absence of the primary seta TR2; (iii) absence of a ventroapical spinula on antennomere 3; and (iv) more proximal position of the primary seta UR8 on urogomphomere 1. Larvae of Herophydrus musicus are very similar morphologically to members of Hygrotus s. lat. lacking natatory setae on legs.
Description of the larvae of Hydroporus ferrugineus Stephens and H-polaris fall (Coleoptera: Adephaga: Dytiscidae)
Alarie, Y. ; Wood, P.J. ; Bruyn, A.M.H. de; Cuppen, J.G.M. - \ 2001
Aquatic Insects 23 (2001)2. - ISSN 0165-0424 - p. 123 - 133.
Description of structures of the larvae of Hydroporus ferrugineus Stephens and H. polaris Fall is provided including detailed chaetotaxal and porotaxal analyses. Larvae of H. ferrugineus are distinguished from all other species of Hydroporus Clairville by the presence of 1–2 secondary setae on urogomphomere 1. Larvae of H. polaris are distinguished from all other Nearctic counterparts by the absence of lateral spinulae on the prementum and more elongate urogomphi.
Water sector strategy and action plan
Buijs, J. ; Graaff, J. de; White, M. ; Stephens, C. ; McCalla, W. - \ 2000
Kingston/Delft : BKH Consulting Engineers - 400 p.
Non-reciprocal cross-incompatibility in Trichogramma deion.
Stouthamer, R. ; Luck, R.F. ; Pinto, J.D. ; Platner, G.R. ; Stephens, B. - \ 1996
Entomologia Experimentalis et Applicata 80 (1996). - ISSN 0013-8703 - p. 481 - 489.
Check title to add to marked list
<< previous | next >>

Show 20 50 100 records per page

 
Please log in to use this service. Login as Wageningen University & Research user or guest user in upper right hand corner of this page.