|Autoethnography and power in a tourism researcher position: A self-reflexive exploration of unawareness, memories and paternalism among Namibian Bushmen
Koot, S.P. - \ 2019
In: Tourism Ethnographies: Ethics, Methods, Application and Reflexivity / Andrews, Hazel, Jimura, Takamitsu, Dixon, Laura, Routledge, Taylor & Francis Group - ISBN 9781138061767 - p. 52 - 66.
|The Potato Nucleotide-binding Leucine-rich Repeat (NLR) Immune Receptor Rx1 regulates a multi-protein immune complex at chromatin
Llewelyn, Alex ; Townsend, Philip D. ; Fenyk, Stepan ; Dixon, Christopher ; Palsson, Lars-Olof ; Gawehns, Fleur ; Takken, F. ; Slootweg, E.J. ; Sukarta, O.C.A. ; Goverse, A. ; Cann, Martin J. - \ 2019
|The pastoral farming system: Balancing between tradition and transition
Leeuw, J. de; Osano, P. ; Said, M. ; Ayantunde, A.A. ; Dube, S. ; Neely, C. ; Vrieling, A. ; Thornton, P. ; Ericksen, P. - \ 2019
In: Farming Systems and Food Security in Africa / Dixon, J., Garrity, D.P., Boffa, J.M., Williams, T.O., Amede, T., Auricht, C., Lott, R., Mburathi, G., Routledge, Taylor & Francis Group (Earthsan food and agriculture ) - ISBN 9781138963351
|Farming and food systems potentials
Dixon, J. ; Boffa, J.M. ; Williams, T.O. ; Leeuw, J. de; Fischer, G. ; Velthuizen, H. van - \ 2019
In: Farming Systems and Food Security in Africa / Dixon, J., Garrity, D., Boffa, J.M., Williams, T.O., Amede, T., Auricht, C., Lott, R., Mburathi, G., Routledge, Taylor & Francis Group (Earthscan food and agriculture ) - ISBN 9781138963351
Drivers of vegetable consumption in urban Nigeria : Food choice motives, knowledge, and self-efficacy
Raaijmakers, Ireen ; Snoek, Harriette ; Maziya-Dixon, Busie ; Achterbosch, Thom - \ 2018
Sustainability 10 (2018)12. - ISSN 2071-1050
Food choice motives - Food environment - Knowledge - Nigeria - Self-efficacy - Socio-economic classes - Vegetable consumption
Objective: This study aimed to provide insights into vegetable consumption behavior of urban Nigerian consumers across different Socio-Economic Classes (SEC), their main food choice motives, and the associations of these motives and other drivers with vegetable consumption. Methods: An online survey was conducted in which 1220 women from Lagos (N = 808) and Ibadan (N = 412) metropolis from different SEC participated. Results: On average, respondents reported to consume 2.6 portions of vegetables per day. Most vegetables were bought at open and traditional markets, were bought fresh rather than processed, and were consumed cooked. Respondents from the second richest and upper middle SEC consumed most vegetables () and higher SEC consumed a larger variety of vegetables compared to those from lower classes. Respondents who reported to have a higher knowledge of vegetable consumption, had a higher belief in one's own ability to prepare vegetables (self-efficacy), and those that valued the food motive Mood and Health more, reported a higher vegetable intake. Conclusions: Vegetable consumption in the studied cities in Nigeria was below recommendations. Increasing knowledge and self-efficacy might be a way to increase consumption, especially in combination with interventions in the food environment and product design focused on the motives Health and Mood, and considering the importance of differences between SEC.
The intracellular immune receptor Rx1 regulates the DNA-binding activity of a Golden2-like transcription factor
Townsend, Philip D. ; Dixon, Christopher H. ; Slootweg, Erik J. ; Sukarta, Octavina C.A. ; Yang, Ally W.H. ; Hughes, Timothy R. ; Sharples, Gary J. ; Palsson, Lars-Olof ; Takken, Frank L.W. ; Goverse, Aska ; Cann, Martin J. - \ 2018
Journal of Biological Chemistry 293 (2018)9. - ISSN 0021-9258 - p. 3218 - 3233.
Plant NLR proteins enable the immune system to recognise and respond to pathogen attack. An early consequence of immune activation is transcriptional reprogramming and some NLRs have been shown to act in the nucleus and interact with transcription factors. The Rx1 NLR protein of potato is further able to bind and distort double-stranded DNA. However, Rx1 host targets that support a role for Rx1 in transcriptional reprogramming at DNA are unknown. Here we report a functional interaction between Rx1 and NbGlk1, a Golden2- like transcription factor. Rx1 binds to NbGlk1 in vitro and in planta. NbGlk1 binds to known Golden2-like consensus DNA sequences. Rx1 reduces the binding affinity of NbGlk1 for DNA in vitro. NbGlk1 activates cellular responses to potato virus X, whereas Rx1 associates with NbGlk1 and prevents its assembly on DNA in planta unless activated by PVX. This study provides new mechanistic insight into how an NLR can co-ordinate an immune signalling response at DNA following pathogen perception.
Landslides and climate change in the United Kingdoms
Dijkstra, T.A. ; Jenkins, G.O. ; Gunn, D. ; Dashwood, C. ; Dankers, R. ; Dixon, N. ; Petley, D.N. ; Gibson, A. ; Winter, M.G. - \ 2017
In: Slope Safety Preparedness for Impact of Climate Change CRC Press - ISBN 9781138032309 - p. 437 - 478.
This report is a contribution to the Joint Technical Committee (JTC) 1 ‘Natural Slopes and Landslides’. The objectives of this UK country report are (1) to provide an overview of landslide activity, (2) to sketch the climate change context and highlight examples of research into the possible consequences for landslide activity, and (3) to discuss the relevant regulatory framework and multi-disciplinary hazard assessment.
Letter to the editor: Elevating the conversation about GE crops
Gould, Fred ; Amasino, Richard M. ; Brossard, Dominique ; Buell, C.R. ; DIxon, Richard A. ; Falck-Zepeda, Jose B. ; Gallo, Michael A. ; Giller, Ken E. ; Glenna, Leland L. ; Griffin, Timothy ; Hamaker, Bruce R. ; Kareiva, Peter M. ; Magraw, Daniel ; Mallory-Smith, Carol ; Pixley, Kevin V. ; Ransom, Elizabeth P. ; Rodemeyer, Michael ; Stelly, David M. ; Stewart, C.N. ; Whitaker, Robert J. - \ 2017
Nature Biotechnology 35 (2017)4. - ISSN 1087-0156 - p. 302 - 304.
A system perspective on the choice determinants of vegetable consumption and balanced diets in urban Nigeria
Raaijmakers, Ireen ; Achterbosch, T.J. ; Tacken, G.M.L. ; Maziya-Dixon, B. - \ 2017
Integrating canopy and large-scale atmospheric effects in the convective boundary-layer dynamics and chemistry during the CHATS experiment
Shapkalijevski, M. ; Ouwersloot, Huug ; Moene, A.F. ; Vilà-Guerau De Arellano, J. - \ 2017
Atmospheric Chemistry and Physics 17 (2017). - ISSN 1680-7316 - p. 1623 - 1640.
By characterizing the dynamics of a convective boundary layer above a relatively sparse and uniform orchard canopy, we investigated the impact of the roughness-sublayer (RSL) representation on the predicted diurnal variability of surface fluxes and state variables. Our approach combined numerical experiments, using an atmospheric mixed-layer model including a land-surface-vegetation representation, and measurements from the Canopy Horizontal Array Turbulence Study (CHATS) field experiment near Dixon, California. The RSL is parameterized using an additional factor in the standard Monin–Obukhov similarity theory flux-profile relationships that takes into account the canopy influence on the atmospheric flow. We selected a representative case characterized by southerly wind conditions to ensure well-developed RSL over the orchard canopy. We then investigated the sensitivity of the diurnal variability of the boundary-layer dynamics to the changes in the RSL key scales, the canopy adjustment length scale, Lc, and the β = u*/|U| ratio at the top of the canopy due to their stability and dependence on canopy structure. We found that the inclusion of the RSL parameterization resulted in improved prediction of the diurnal evolution of the near-surface mean quantities (e.g. up to 50 % for the wind velocity) and transfer (drag) coefficients. We found relatively insignificant effects on the modelled surface fluxes (e.g. up to 5 % for the friction velocity, while 3 % for the sensible and latent heat), which is due to the compensating effect between the mean gradients and the drag coefficients, both of which are largely affected by the RSL parameterization. When varying Lc (from 10 to 20 m) and β (from 0.25 to 0.4 m), based on observational evidence, the predicted friction velocity is found to vary by up to 25 % and the modelled surface-energy fluxes (sensible heat, SH, and latent heat of evaporation, LE) vary up to 2 and 9 %. Consequently, the boundary-layer height varies up to 6 %. Furthermore, our analysis indicated that to interpret the CHATS measurements above the canopy, the contributions of non-local effects such as entrainment, subsidence and the advection of heat and moisture over the CHATS site need to be taken into account.
Integrating canopy and large-scale atmospheric effects in the convective boundary-layer dynamics and chemistry during the CHATS experiment
Shapkalijevski, M. ; Brown, J. ; Vilà-Guerau De Arellano, J. ; Ouwersloot, Huug ; Moene, A.F. - \ 2016
- p. J11.3 - J11.3.
We study the impact of the roughness sublayer (RSL), formed over a relatively sparse canopy, on the dynamics of convective-boundary layers, as well as on the exchange of reactants in and above the canopy. Our approach combines numerical experiments using an atmospheric mixed-layer model coupled to a land surface-vegetation representation and observations collected at different heights in and above the RSL during the Canopy Horizontal Array Turbulence Study (CHATS) field experiment near Dixon, California. Within the modelling system, the RSL is parameterized using a formulation that accounts for the deviation of the standard Monin-Obukhov Similarity Theory flux-profile relationships due to the presence of a canopy. We select two representative days with different wind conditions and canopy fetch to determine the sensitivity of the applied RSL formulation to the diurnal variability of thermodynamic and reactant profiles. We present the diurnal evolution of the surface momentum, energy fluxes and boundary-layer height, as well as the evolution of the mean wind, potential temperature and specific humidity in and above the RSL. This study is extended to infer the fluxes of ozone, NO and NO2, using the observations of their mean gradients, applying different retrieval formulations including and omitting the RSL effects. Finally, these retrieved fluxes are used to determine the ozone budget in the convective boundary layer. We find that the presence of an RSL has relatively small impact on surface fluxes (<3%). This is due to the compensating effect of the mean gradients of the state variables and the calculated drag coefficients for momentum and scalar, which are largely affected by the canopy presence. The friction velocity is found to be sensitive to variations in the canopy adjusted length scale and the u*⁄U ratio. These variations of the friction velocity (up to 15% relative to the case-study value) resulted in an impact on the diurnal variation of the surface energy fluxes and consequently on the convective boundary-layer dynamics of up to 6%. For the reactants, we find its maximal deposition near the canopy top. Furthermore, our results show significant differences in the retrieved deposition fluxes of the reactants depending on the method used for their calculation from the gradients (e.g. up to 30% error in retrieved ozone fluxes when RSL is omitted). Finally, although deposition plays an important contribution in the diurnal variability of the ozone budget, our calculations indicate the relevance of reactivity and non-local effect contributions such as entrainment from the free troposphere and advection.
Biofortified yellow cassava and Vitamin A status of Kenyan children : A randomized controlled trial
Talsma, E.F. ; Brouwer, I.D. ; Verhoef, Hans ; Mbera, G.N.K. ; Mwangi, A.M. ; Demir, A.Y. ; Maziya-Dixon, B. ; Boy, Erick ; Zimmermann, M.B. ; Melse-Boonstra, Alida - \ 2016
American Journal of Clinical Nutrition 103 (2016)1. - ISSN 0002-9165 - p. 258 - 267.
Biofortification - Efficacy - Food-based approach - Nutrition-sensitive intervention - Vitamin A
Background: Whereas conventional white cassava roots are devoid of provitamin A, biofortified yellow varieties are naturally rich in b-carotene, the primary provitamin A carotenoid. Objective: We assessed the effect of consuming yellow cassava on serum retinol concentration in Kenyan schoolchildren with marginal vitamin A status. Design: We randomly allocated 342 children aged 5-13 y to receive daily, 6 d/wk, for 18.5 wk 1) white cassava and placebo supplement (control group), 2) provitamin A-rich cassava (mean content: 1460 μg β-carotene/d) and placebo supplement (yellow cassava group), and 3) white cassava and β-carotene supplement (1053 mg/d; β-carotene supplement group). The primary outcome was serum retinol concentration; prespecified secondary outcomes were hemoglobin concentration and serum concentrations of β-carotene, retinol-binding protein, and prealbumin. Groups were compared by using ANCOVA, adjusting for inflammation, baseline serum concentrations of retinol and β-carotene, and stratified design. Results: The baseline prevalence of serum retinol concentration
RED versus REDD : Biofuel policy versus forest conservation
Dixon, Peter ; Meijl, Hans van; Rimmer, Maureen ; Shutes, Lindsay ; Tabeau, Andrzej - \ 2016
Economic Modelling 52 (2016)B. - ISSN 0264-9993 - p. 366 - 374.
Computable general equilibrium - Land use changes - Land-supply function - REDD - Renewable Energy Directives
We examine the interplay between Renewable Energy Directives (RED) and the United Nations Programme to Reduce Emissions from Deforestation and Forest Degradation (REDD) using a scenario approach with a recursive-dynamic global computable general equilibrium model. A methodological issue addressed in the paper is the specification of the supply of agricultural land in the face of restrictions over its availability, as arises under REDD. By giving magnitudes to the effects of REDD and RED, our simulations provide a defense against environmental skeptics who, in the absence of such estimates, can dismiss these policies as being exorbitantly expensive. Although REDD and RED are in tension with respect to land use, the paper shows that they could be implemented simultaneously without significant global problems for food supply. The paper does however pinpoint some regional problems. Implementation of RED and REDD would cause large increases in food prices in Indonesia and Southern Africa. The methodology used in this paper, if implemented at a more detailed level, could be the basis of working out compensation packages that would be needed to make pervasive RED and REDD policies politically feasible.
Revisiting GMOs : Are there differences in European consumers' acceptance and valuation for cisgenically vs transgenically bred rice?
Delwaide, Anne Cécile ; Nalley, Lawton L. ; Dixon, Bruce L. ; Danforth, Diana M. ; Nayga, Rodolfo M. ; Loo, Ellen J. Van; Verbeke, Wim - \ 2015
PLoS ONE 10 (2015)5. - ISSN 1932-6203
Both cisgenesis and transgenesis are plant breeding techniques that can be used to introduce new genes into plant genomes. However, transgenesis uses gene(s) from a non-plant organism or from a donor plant that is sexually incompatible with the recipient plant while cisgenesis involves the introduction of gene(s) from a crossable - sexually compatible - plant. Traditional breeding techniques could possibly achieve the same results as those from cisgenesis, but would require a much larger timeframe. Cisgenesis allows plant breeders to enhance an existing cultivar more quickly and with little to no genetic drag. The current regulation in the European Union (EU) on genetically modified organisms (GMOs) treats cisgenic plants the same as transgenic plants and both are mandatorily labeled as GMOs. This study estimates European consumers' willingness-to-pay (WTP) for rice labeled as GM, cisgenic, with environmental benefits (which cisgenesis could provide), or any combination of these three attributes. Data were collected from 3,002 participants through an online survey administered in Belgium, France, the Netherlands, Spain and the United Kingdom in 2013. Censored regression models were used to model consumers' WTP in each country. Model estimates highlight significant differences in WTP across countries. In all five countries, consumers are willing-to-pay a premium to avoid purchasing rice labeled as GM. In all countries except Spain, consumers have a significantly higher WTP to avoid consuming rice labeled as GM compared to rice labeled as cisgenic, suggesting that inserting genes from the plant's own gene pool is more acceptable to consumers. Additionally, French consumers are willing-to-pay a premium for rice labeled as having environmental benefits compared to conventional rice. These findings suggest that not all GMOs are the same in consumers' eyes and thus, from a consumer preference perspective, the differences between transgenic and cisgenic products are recommended to be reflected in GMO labeling and trade policies.
Synchronous failure : The emerging causal architecture of global crisis
Homer-Dixon, T. ; Walker, B. ; Biggs, R. ; Crepin, A.S. ; Folke, C. ; Lambin, E.F. ; Peterson, G.D. ; Rockstrom, J. ; Scheffer, M. ; Troell, M. - \ 2015
Ecology and Society 20 (2015)3. - ISSN 1708-3087 - 16 p.
Climate change - Conventional oil - Financial system - Global crises - Grain supply - Social-ecological system
Recent global crises reveal an emerging pattern of causation that could increasingly characterize the birth and progress of future global crises. A conceptual framework identifies this pattern’s deep causes, intermediate processes, and ultimate outcomes. The framework shows how multiple stresses can interact within a single social-ecological system to cause a shift in that system’s behavior, how simultaneous shifts of this kind in several largely discrete social-ecological systems can interact to cause a far larger intersystemic crisis, and how such a larger crisis can then rapidly propagate across multiple system boundaries to the global scale. Case studies of the 2008-2009 financial-energy and food-energy crises illustrate the framework. Suggestions are offered for future research to explore further the framework’s propositions. © 2015 by the author(s).
The Potato Nucleotide-Binding Leucine-Rich Repeat (NLR) Immune Receptor Rx1 is a Pathogen Dependent DNA-Deforming Protein
Fenyk, S. ; Townsend, P.D. ; Dixon, C.H. ; Spies, G.B. ; Campillo, A.S.E. ; Slootweg, E.J. ; Westerhof, L.B. ; Gawehns, F.K.K. ; Knight, M.R. ; Sharples, G.J. ; Goverse, A. ; Palsson, L.O. ; Takken, F.L.W. ; Cann, M.J. - \ 2015
Journal of Biological Chemistry 290 (2015)41. - ISSN 0021-9258 - p. 24945 - 24960.
Plant NLR proteins enable cells to respond to pathogen attack. Several NLRs act in the nucleus, however, conserved nuclear targets that support their role in immunity are unknown. Previously we noted a structural homology between the NB domain of NLRs and DNA replication origin-binding Cdc6/Orc1 proteins. Here we show that the NB-ARC domain of the Rx1 NLR of potato binds nucleic acids. Rx1 induces ATP-dependent bending and melting of DNA in vitro dependent upon a functional P-loop. In situ full-length Rx1 binds nuclear DNA following activation by its cognate pathogen-derived effector protein, the coat protein of potato virus X. In line with its obligatory nucleocytoplasmic distribution, DNA-binding was only observed when Rx1 was allowed to freely translocate between both compartments and was activated in the cytoplasm. Immune activation induced by an unrelated NLR-effector pair did not trigger a Rx1-DNA interaction. DNA-binding is therefore not merely a consequence of immune activation. These data establish a role for DNA distortion in Rx1 immune signalling and defines DNA as a molecular target of an activated NLR.
A study on the potential of insect protein and lipid as a food source
Yi, L. - \ 2015
Wageningen University. Promotor(en): Tiny van Boekel; Arnold van Huis, co-promotor(en): Catriona Lakemond. - Wageningen : Wageningen University - ISBN 9789462572560 - 186
eiwitbronnen - nieuwe voedingsmiddelen - insecten als voedsel - extractie - eiwitten - vleesvervangers - fysicochemische eigenschappen - protein sources - novel foods - insects as food - extraction - proteins - meat alternates - physicochemical properties
Propositions belonging to the thesis, entitled:‘A study on the potential of insect protein and lipid as a food source’. Liya Yi
Wageningen, 9 February 2015.High protein quality is, next to high protein content, a major argument to use insects as an alternative protein source. (this thesis)
With respect to aqueous extraction, proteins from Tenebrio molitor behave similarly as proteins from meat and fish. (this thesis)
In contrast to what Pascucci & Magistris (2013) claim, consumer information is not enough to achieve consumer acceptance of novel food.
Pascucci, S., & Magistris, T. d. (2013). International Food and Agribusiness Management Review, 16, 1-16.
Reducing environmental impact by changing human diet into a plant-based diet (Joyce, Dixon, Comfort, & Hallett, 2012) will not result in meeting the increasing global food demand.Joyce, A., Dixon, S., Comfort, J., & Hallett, J. (2012). Journal of Environmental and Public Health, 2012, 7.
Scientific evidence and the availability of technology are not guarantees for a change in human behaviour.
The statement of the Finnish writer Sebastyne Young “We all want to be extraordinary and we all just want to fit in. Unfortunately, extraordinary people rarely fit in.” applies to science where generation of extraordinary knowledge results in less fitting in.
Bioenergy production from waste agricultural biomass
Quist-Wessel, Foluke P.M. ; Langeveld, J.W.A. - \ 2014
In: Biofuel Cropping Systems / Langeveld, H., Dixon, J., van Keulen, H., London : Taylor and Francis - ISBN 9780415539531 - p. 226 - 238.
An inventory of biomass availability presented by Dornburg et al. (2010) suggests that agricultural and forestry residues could provide an equivalent of 85 EJ of energy in 2050. According to IEA Bioenergy (2011), wastes and residues together with sustainably grown energy crops should be able to provide the majority of the biomass feedstock requirements needed to realise biofuel, as well as heat and power targets in 2050, but the exact amount and character remain unrevealed.
Oil palm biodiesel in the far east
Langeveld, J.W.A. ; Quist-Wessel, Foluke P.M. ; Croezen, Harry - \ 2014
In: Biofuel Cropping Systems / Langeveld, H., Dixon, J., van Keulen, H., Taylor and Francis - ISBN 9780415539531 - p. 158 - 173.
Palm oil increasingly is used as feedstock for biodiesel production, although volumes remain much smaller than those for other major oil crops (soybean, rapeseed). The main producers of palm oil are Indonesia and Malaysia. This chapter discusses the production of palm oil in these countries, and for conciseness, we refer to them as the Far East. Normally, more countries in the region are included in this term, but they do not produce much palm oil.
Biofuel production in Brazil
Langeveld, J.W.A. ; Quist-Wessel, Foluke P.M. - \ 2014
In: Biofuel Cropping Systems / Langeveld, H., Dixon, J., van Keulen, H., London : Taylor and Francis - ISBN 9780415539531 - p. 63 - 86.
Brazil, the largest country in Latin America and the world’s seventhwealthiest nation (in 2011), has a GDP of more than US$2 trillion and a population of 190 million. This former developing country reached middleincome status and now is considered a dynamic emerging economy similar to Russia, India, China and South Africa (the so-called BRICS countries). Since 2001 sustained economic growth, low inflation, social programs, and increased minimum wage have helped to halve poverty. Between 2004 and 2009 the share of the population earning less than US$1.25 per day (the extremely poor) dropped from 10% to 2%, which is an amazing achievement. During that period, the poor enjoyed income growth rates four times higher than those of the rich. Despite this, inequality remains high, and there is still a large gap between the poor and rich; for example, with respect to education (World Bank, 2013).